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NUMBER 29 – 2017

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DIRECTORATE-GENERAL FOR NUCLEAR AND TECHNOLOGICAL DEVELOPMENT OF THE NAVY (DGDNTM)

NUMBER 29 – 2017

Revista Pesquisa Naval / Diretoria-Geral de Desenvolvimento Nuclear e Tecnológico da Marinhav. 1, n. 1, 1988 – Brasília – DF – Brasil – Marinha do Brasil

AnualTítulo abreviado: Pesq. Nav.ISSN Impresso 1414-8595 / ISSN Eletrônico 2179-0655

1. Marinha – Periódico – Pesquisa Cientifica. Diretoria-Geral de Desenvolvimento Nuclear e Tecnológico da Marinha.

CDU 001.891.623/.9CDD 623.807.2

The mission of the Revista Pesquisa Naval is to provide a formal channel of communication and dissemination of national scientific and technical productions for the scientific community, by publishing original articles that are a result of scientific research and contribute to the advancement of knowledge in areas of interest for the Brazilian Navy. Articles published in the journal do not reflect the position or the doctrine of the Navy and are the sole responsibility of the authors.

SPONSORSHIP Directorate-General for Nuclear and Technological Development of the Navy – DGDNTM

EDITOR-IN-CHIEF Admiral Bento Costa Lima Leite de Albuquerque JuniorDirector General of Nuclear and Technological Development of the Navy

ASSISTANT EDITORSVADM (NE) Sydney dos Santos Neves Director of the Technological Center of the Navy in São Paulo - CTMSP

RADM Alfredo Martins MuradasDirector of the Technological Center of the Navy in Rio de Janeiro – CTMRJ RADM (RM1-EN) Humberto Moraes RuivoDirector of the Naval Agency for Nuclear Safety and Quality – AgNSNQ

EDITORIAL BOARD CAPT Antônio Capistrano de Freitas FilhoCAPT José Fernando De Negri CAPT (RM1) Carlos Alberto de Abreu MadeiraCDR Benjamin Dante Rodrigues Duarte Lima LCDR (NE) Elaine Rodino da Silva2SG-RO Rogério Augusto dos Santos3SG-ELEC Renato Ellyson Oliveira Cavalcante

EDIÇÃODirectorate-General for Nuclear and Technological Development of the Navy – DGDNTMwww.marinha.mil.br/dgdntm/revista

EDITORIAL PRODUCTION Zeppelini Publishers / Instituto Filantropia www.zeppelini.com.br

THE REVISTA PESQUISA NAVAL IS SPONSORED BY

Ademir Oliveira da Silva – UFRN – Natal/RN/BrazilAdolfo Gustavo Serra Seca Neto – UTFPR – Curitiba/PR/BrazilAlexandre Nicolaos Simos – USP – São Paulo/SP/BrazilAlexandre Queiroz Bracarense – UFMG – Belo Horizonte/MG/BrazilAndré Gustavo Adami – UCS – Caxias do Sul/RS/BrazilAndré Oliveira Paggiaro – FMUSP– São Paulo/SP/BrazilBartira Ercilia Pinheiro da Costa – PUC-RS – Porto Alegre/RS/BrazilBruna Lavinas Sayed Picciani – UFF – Rio de Janeiro/RJ/BrazilCarlos Alberto Mendes Moraes – UNISINOS – Porto Alegre/RS/BrazilCarlos Dias Maciel – USP – São Paulo/SP/BrazilDaniel Pacheco Lacerda – UNISINOS – Porto Alegre/RS/Brazil Daniela Ota Hisayasu Suzuki – UFSC – Florianópolis /SC/Brazil Eduardo Rodrigues Vale – UFF – Rio de Janeiro/RJ/BrazilEdson Noriyuki Ito – UFRN – Natal/RN/Brazil Fernando Cesar Coelli – CEFET – Rio de Janeiro/RJ/Brazil Fernando de Carvalho da Silva – UFF – Rio de Janeiro/RJ/BrazilGilson Brito Alves Lima – UFF – Rio de Janeiro/RJ/BrazilGladson Silva Fontes – IME – Rio de Janeiro/RJ/Brazil

João Carlos Damasceno Lima – UFSM – Santa Maria/RS/BrazilJosé Benedito Marcomini – USP – São Paulo/SP/BrazilJosé Manoel de Seixas – UFRJ – Rio de Janeiro/RJ/BrazilLeandro Carlos de Souza – UFERSA – Mossoró/RN/BrazilLetivan Gonçalves de Mendonça Filho – IME – Rio de Janeiro/RJ/BrazilLinilson Rodrigues Padovese – USP – São Paulo/SP/BrazilLuiz Eduardo Moreira Carvalho de Oliveira – UNICAMP – Campinas/SP/Brazil Marcelo de Almeida Santos Neves – UFRJ – Rio de Janeiro/RJ/BrazilMarco Antônio Roxo da Silva – UFF – Rio de Janeiro/RJ/BrazilMiguel Afonso Sellitto – UNISINOS – Porto Alegre/RS/Brazil Natanael Nunes de Moura – UFRJ – Rio de Janeiro/RJ/Brazil Rodrigo da Rosa Righi – UNISINOS – Porto Alegre/RS/BrazilRonaldo Pinheiro da Rocha Paranhos – UENF – Campos dos Goitacazes/RJ/BrazilSidnei Moura e Silva – UCS – Caxias do Sul/RS/BrazilSimone de Lima Martins – UFF – Rio de Janeiro/RJ/BrazilThomas Gabriel Rosauro Clarke – LAMEF/UFRGS – Porto Alegre/RS/BrazilVivian Resende – UFMG – Belo Horizonte/MG/Brazil Waldek Wladimir Bose Filho – USP – São Paulo/SP/Brazil

EDITORIAL COMMISSION

1 PRESENTATIONBento Costa Lima Leite de Albuquerque Junior

OPERATIONAL ENVIRONMENT

2 THE INFLUENCE OF HUMAN ERROR ON THE CBRN DEFENSE SYSTEM FOR ACCIDENT SCENARIOS IN THE CR-EBNInfluência da falha humana no sistema de defesa NBQR para cenários acidentais no CR-EBN Leonardo Amorim do Amaral

NAVAL ARCHITECTURE AND PLATFORMS

10 DEVELOPMENT AND INITIAL TESTS OF THE BRAZILIAN NAVY SUBMARINE FREE MODEL ML01Desenvolvimento e ensaios iniciais do modelo livre de submarino ML01 da Marinha do BrasilHélio Correa da Silva Junior, Walfrido Nivaldo Barnack Neto, Leandro Pansanato, Ricardo Sbragio, Leonardo Pinheiro da Silva, Fernando Moya Orsatti

HUMAN PERFORMANCE AND HEALTH

20 CLINICAL ENGINEERING AS AN AGENT FOR IMPROVING THE QUALITY OF MEDICAL CAREA engenharia clínica como agente de melhoria da qualidadedo atendimento médicoGlauco Barbosa da Silva, Nival Nunes de Almeida

30 HIGH HYDROSTATIC PRESSURE APPLIED IN THE PROCESS OF STERILIZING BIOLOGIC DRESSINGS MADE OF HUMAN AMNIOTIC MEMBRANESAlta pressão hidrostática aplicada no processo de esterilização de curativo biológico constituído por membrana amniótica humanaShana Priscila Coutinho Barroso, Rachel Antonioli Santos, Jerson Lima da Silva, Marcelo Leal Gregório

40 A SIMULTANEOUS ANALYSIS OF TETRAHYDROCANNABINOL AND CARBOXY-TETRAHYDROCANNABINOL IN URINE SAMPLESAnálise simultânea de tetrahidrocanabinol e carboxi-tetrahidrocanabinol em amostras de urinaCarla Sales Maia, Daniel Filisberto Schulz, Cláudio Cerqueira Lopes, Rosângela Sabbatini Capella Lopes, André Luiz Mazzei Albert

SPECIAL MATERIALS

49 DEVELOPMENT OF NATIONAL BASE BLEED PROPELLANT GRAIN APPLIED FOR EXTENDED RANGE AMMUNITIONDesenvolvimento de grão propelente base bleed nacional para aplicação em munição de alcance estendidoMaurício Ferraponto� Lemos, Priscila Simões Teixeira Amaral Paula, Arnaldo Miceli, Laurílio José da Silva Júnior, Edson da Silva Souza

CONTENTS | NUMBER 29 – 2017

DECISION-MAKING PROCESS

59 SOLUTION OF THE MULTI-LAYER AIR DEFENSE WEAPON ALLOCATION PROBLEM WITH THE MONTE CARLO SCANNING METHODSolução do problema de alocação de armas de defesa aérea em multicamadas com o método Monte Carlo ScanningAlexandre David Caldeira, Wilson José Vieira

67 EVOLUTIONARY PROGRAMMING MODEL FOR ACTIVITY PLANNING IN MAINTENANCE WORKSHOPSUm modelo de programação evolucionária para programação de atividades em oficinas de manutençãoManoel Carlos Pego Saisse, Sergio Medeiros da Nobrega, Rafael Novaes Lago, Lianderson Giorges Leite Rodrigues, Leonardo Amorim do Amaral

SENSORS, ELECTRONIC WARFARE AND ACOUSTIC WARFARE

76 THE FIRST VERSION OF AN UNDERWATER ACOUSTIC SOFTWARE-DEFINED MODEM FOR THE BRAZILIAN NAVYPrimeira versão de um modem acústico submarino definido por software da Marinha do BrasilAlexandre Geddes Lemos Guarino, Fábio Contrera Xavier, Luis Felipe Pereira dos Santos Silva, Je�erson Osowsky

86 RESOLUTION OF PORT-STARBOARD AMBIGUITY IN A TOWED ARRAY OF HYDROPHONESResolução da ambiguidade boreste-bombordo em arranjo de hidrofones rebocadoStilson Veras Cardoso

Revista Pesquisa Naval, Brasília - DF, n. 29, 2017, p. 1

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PRESENTATION

PRESENTATION

The promotion of productive and technological Brazilian autonomy in the defense area has been clearly expressed in the Brazilian National Defense Policy and requires the concentra-tion of efforts to stimulate research and development of tech-nologies through human capital qualifi cation and improvement of the installed capabilities of the Defense Industrial Base.

The alignment and compromise of the Brazilian Navy with this and other principles expressed in high-level documents refl ect on our Strategy of Science, Technology and Innovation (ST&I, acronym in Portuguese), which guides the continuous work of scientifi c, technological, and innovation institutions with the support and partnership of the main university and indus-try centers to promote and implement the necessary actions for performing projects of great relevance. Thus, the ST&I Sector contributes to provide new capabilities so that the Navy fulfi lls its constitutional attributions, while multiplying the knowledge of innovative and dual use for the Brazilian state demands.

Thus, in this edition of the “Revista Pesquisa Naval” Journal, we once more highlight the new acquirements of

our researchers and scientists that are applied to the naval environment. The articles offer solutions and techniques in the segments of decisive, sensory processes, electronic and acoustic wars, human performance, special materials, oper-ational environment, architecture, and naval platforms.

While we obtain important milestones in our strategic programs, I congratulate the authors and their teams for the contribution and work performed, as well as I support the other researchers and readers to keep trying on their under-takings, in the untiring search for concretizing projects that may effectively contribute to obtaining a Navy that is com-patible with the Brazilian level.

AdmiralDirector-General

Revista Pesquisa Naval, Brasília - DF, n. 29, 2017, p. 2-9

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OPERATIONAL ENVIRONMENT

THE INFLUENCE OF HUMAN ERROR ON THE CBRN DEFENSE SYSTEM FOR

ACCIDENT SCENARIOS IN THE CR-EBNInfluência da falha humana no sistema de defesa

NBQR para cenários acidentais no CR-EBN

Leonardo Amorim do Amaral1

1. Frigate Captain (FC); Head of the Department of Science, Technology and Innovation at Marine Corps Technology Center; Master’s degree in Nuclear Engineering from Universidade Federal do Rio de Janeiro – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

Abstract: �is paper presents a risk safety analysis study of accident scenarios postulated in operations removing radioactive liquid waste from the Brazilian Nuclear Propulsion Submarine (Submarino de Propulsão Nuclear Brasileiro–SN-BR), over its lifetime and when in maintenance periods at the Radiological Shipyard Complex and the Naval Base of Itaguai (Complexo Radiológico do Estaleiro e Base Naval de Itaguaí — CR-EBN). Furthermore, it presents the e�ects of these accidents when the CBRN Defense System of the Itaguaí CBRN Defense Battalion operates and makes mistakes in the pro-cedures to control and mitigate the e�ects.Keywords: Safety analysis. Human error. Chemical, Biological, Radiological, and Nuclear Defense. Risk Matrix.

Resumo: Este artigo apresenta um estudo de análise de segurança de risco para cenários acidentais postulados ocorridos em opera-ções de remoção de rejeito líquido radioativo do Submarino de Propulsão Nuclear Brasileiro (SN-BR) em períodos de manuten-ção no Complexo Radiológico do Estaleiro e Base Naval de Itaguaí (CR-EBN) ao longo de sua vida útil, e a in�uência dos efeitos dos acidentes quando o Sistema de Defesa Nuclear, Biológica, Química e Radiológica (SisDefNBQR), do Batalhão de Defesa NBQR-Itaguaí, for acionado e cometer erros de procedimentos para controlar e mitigar as consequências desses eventos.Palavras-chave: Análise de Segurança. Falha Humana. Defesa Nuclear, Biológica, Química e Radiológica. Matriz de Risco.

1. INTRODUCTION

The Chemical, Biological, Nuclear, and Radiological (CBRN) Defense System was implemented through Ordinance No. 83, in 2011 by the Navy’s Chief of Staff with the purpose of combating nuclear, biological, and chemical emergencies, either in the context of naval oper-ations or under actions of the Law and Order Guarantee (Garantia da Lei e da Ordem—GLO), in addition to being able to act in cases of accidents in different nuclear installations (BRAZIL, 2011). In the Brazilian Navy (BN), the Marine Corps (MC) is tasked with monitor-ing the operation of CBRNDefSys-BN, overseeing the

recruitment and technical preparation of military per-sonnel involved, obtaining and maintaining Chemical, Biological, Nuclear, and Radiological (CBRN) actions (MEDEIROS, 2014).

Training and specialization of personnel working in the aforementioned system, operational conditions, and aspects related to Science and Technology are some of the basic requirements that will directly in�uence the type of response to an accident in which there is a possibility of radioactive material leakage into the environment, causing damage to peo-ple, facilities, material, and the environment. In order to meet this demand, the Brazilian Navy CBRN Defense System (CBRNDefSys-BN) was divided into four levels of action.

Leonardo Amorim do Amaral


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Among them, it is worth noting the level at which the issues related to BN’s sensitive installations of the Navy’s Nuclear Program (Programa Nuclear da Marinha — PNM) are stud-ied. To this end, the CBRN-ARAMAR Defense Battalion was created to support the Aramar Experimental Center. �e CBRN-ITAGUAÍ Defense Battalion will be activated once its facilities are built and provide assist the Radiological Shipyard Complex and the Naval Base of Itaguaí (Complexo Radiológico do Estaleiro e Base Naval de Itaguaí — CR-EBN) (BRAZIL, 2011).

CR-EBN is a multiple ground support system for con-ventional and nuclear-powered submarines (SN-BR) aimed to support the SN-BR whenever necessary; for example, when it is anchored at or docked onto the mentioned naval station. It may or may not be performing routine activities and, because it also has a radiological complex, it will aim to treat and store radiological materials. CR-EBN is an instal-lation where nuclear and radiological accidents can happen (AMARAL, 2016). �erefore, CBRNDefSys-BN is extremely relevant and fundamental to mitigate the e�ects of these sce-narios, should they occur.

In well-known cases of nuclear accidents such as �ree Mile Island in the United States in 1979 and Chernobyl in former Soviet Union in 1986, the “human error” factor stood out as the major contributor to failures that led to these events of serious proportions (US NUCLEAR REGULATORY COMMISSION, 2000). �erefore, incidents stemming from human error have been incorporated to Probabilistic Security Analyses and Human Reliability Analyses. As a result, sev-eral techniques were used to calculate human error proba-bility, including THERP, OATS, TESEO, CONFUSION MATRIX, SLIM, and SHARP (REASON, 2000).

2. OBJECTIVES

�e safety analysis of the ground facilities supporting SN-BR is complementary to the safety requirements of the submarine itself (GUIMARÃES, 1999). �ese facilities were named CR-EBN. �erefore, application and classi³cation of operating scenarios for SN-BR and its ground support facil-ities could help to understand the matter of nuclear safety at these sites.

Aiming to verify the influence of human error on actions or general procedures of the personnel involved in CBRNDefSys-BN to mitigate and control accidents, the present work proposes a qualitative risk-safety analysis of radioactive material leakage at CR-EBN when support-ing SN-BR.

3. METHODOLOGY

�e Preliminary Hazard Analysis (PHA) technique was used because it encompasses all dangerous events that might originate in the analyzed installations, covering both intrin-sic failures of components or systems and possible human errors (ALVES et al. 2013). PHA can be used in installa-tions in the initial phase of development (which justi³es its application, for CR-EBN is currently in this phase), in design stages, or even in units already in operation. It is per-formed by ³lling out a worksheet for each analysis module of the installation. An example of a spreadsheet is shown in Table 1.

In order to ³ll out the worksheet, the frequencies of acci-dent scenarios are determined and the severity for each one is estimated. Table 2 shows the classi³cation adopted for scenarios identi³ed according to the category of occurrence frequency (MRS, 2005).

Table 3 shows the classi³cation of scenarios identi³ed according to severity (MRS, 2005). �e severity classi³ca-tion for each accident scenario assumed was arbitrated by the estimated amount of radioactive material leaked, follow-ing the criteria shown in Table 4.

�e information in spreadsheets allows to qualify the risks for each accident scenarios using a risk matrix, as shown in Figure 1, in which the classi³cation in colored boxes refers to the risk categories (MRS ESTUDOS AMBIENTAIS, 2005).

For the purposes of this work, we considered accident scenarios that had occurred during operations for removal of liquid waste from the drain tank of the primary reactor circuit and the SN-BR pressurizer relief tank.

Calculating the frequency of an accident scenario (fc) involved the frequency of an event (fop) that was not an error (for example, the annual frequency of radioactive



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liquid waste transfer from an SN-BR over its useful life-time) and the probabilities associated with it (pf), which refer to the occurrence of defects or events that may lead

to errors (for example, equipment failure and procedural errors in a given operation), all expressed by Equation 1 (ALVES et al., 2013):

Table 1. Preliminary Hazard Analysis Worksheet to be used in the study.

Preliminary Hazard Analysis

System: Module: Date: Page:

Hazard Cause(s)Mode(s) of detection

E´ect(s)Frequency category

Severity category

Risk category

RecommendationsScenario number

Table 2. Classification of frequency for the Preliminary Hazard Analysis.

Classification Detail Frequency (a-1) Description

A Occasional f > 10-2Expected to occur at least once during

the lifetime of the installation.

B Likely 10-4 ≤ f ≤ 10-2Expected to occur up to one time during

the lifetime of the installation.

C Unlikely 10-5 ≤ f ≤ 10-4Unlikely to occur during the lifetime of the installation.

D Very unlikely 10-7 ≤ f ≤ 10-5Very unlikely to occur during the

lifetime of the installation.

E Improbable f < 10-7It should not occur during the

lifetime of the installation.

Source: MRS Estudos Ambientais (2005).

Table 3. Classification of severity for the Preliminary Hazard Analysis.

Classification Detail Description

I Catastrophic

Irreparable damage to equipment, property and/or the environment, leading to unplanned shutdown of the unit and/or system

(slow or impossible repair).Causes fatalities or serious injury to several people

(employees and/or people on the outside).

II Critical

Severe damage to equipment, property and/or the environment, leading to an orderly shutdown of the unit and/or system.

Causes moderate injuries to employees, third parties and/or people on the outside (there is a remote possibility of death to

employees and/or third parties).Requires immediate corrective action to prevent

it from becoming catastropic

III Marginal/moderate

Minimal damage to equipment, property and/or the environment (damage is controllable and/or has a low-cost repair).

Causes minor injuries to employees, third parties, and/or people on the outside.

IV Low or insignificant

No damage or insignificant damage to equipment, property and/or the environment.

No injuries or deaths of employees, third parties (non-employees) and/or people on the outside (industries and the community); At most,

cases requiring first aid or minor medical treatment.

Source: MRS Estudos Ambientais (2005).



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fc = fop * pf (1)

In order to calculate the frequency of scenarios with equipment failures (valve leakage, �anges, gaskets, and all of them together), the following Equation 2 (LEWIS, 1996):

Pf = 1-e-(λ1+ λ2)t (2)

in which λ1 and λ 2 are error rates that refer to leakage from equipment involved in the operation.

In order to calculate the probability of human error (pEH) in the general procedures of actions from CBRNDefSys-BN, the THERP technique was used. It has been widely used in the Preliminary Safety Analysis (PSA) of nuclear power plants (BELLO; COLOMBARI, 1980), in addition to the limited information about the facilities and activities carried out in future installations of CR-EBN.

A level of risk was therefore established based on the matrix shown in Figure 1, which indicates the fre-quency and severity of undesired events, according to Tables 2 and 3.

4. RESULTS

For the results obtained and shown in this work, the lifetime of a SN-BR was considered to be 30 years (GUIMARÃES, 1999). The number of maintenance activities performed during its lifetime was also calcu-lated. These data were obtained with information drawn and adapted from a routine maintenance proposal for U.S. submarines. It included initial tests, the beginning of the SN-BR’s operations at sea, end of its lifetime and consequent deactivation. Table 5 shows the calculated number of times the SN-BR goes through maintenance over a period of time. The different time periods were stipulated as compared to the proposal for U.S. subma-rines and the maintenance periods adopted by the BN (BIRKLER et al., 1994).

in order to calculate the frequency of accident sce-narios postulated in this work, the scenarios in which SN-BR was in maintenance period were also considered. Therefore, the Routine Maintenance Period (RMP), the Routine Docking Period (RDP) (without a fuel change), the General Maintenance Period (GMP), and the Final Docking Period (FDP) were assumed for this purpose and resulted in 44 maintenance events. Scenarios related

Table 4. Classification of severity to estimate the amount of leaked radioactive material.

Types of scenarios Severity

Scenarios with minor leakage (up to 10%) of total inventory

Low

Scenarios with a large amount of leakage (up to 50% of total inventory)

Moderate

Scenarios with major leakage (more than 50% of total inventory)

Critical

Scenarios with major leakage, leaking all inventory

Catastrophic

SEVERITY

Low Moderate Critical Catastrophic

FR

EQ

UE

NC

Y

Occasional Insignificant* Moderate* Critical* Catastrophic*

Likely

Unlikely Marginal*

Very Unlikely

Improbable

Source: MRS Estudos Ambientais (2005). *The classifications in the colored boxes refer to di´erent risk categories.

Figure 1. Risk matrix used to classify different accidental scenarios.



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to radioactive liquid waste removal operations were also considered, as they happened in all 44 maintenance occurrences. Each operation was estimated to last two hours. With these data, the frequency was fop = 33.56 × 10-5. This operating frequency is used for all accident scenarios postulated.

As an example, to calculate the probability of failure (Pf) for a scenario with failures in the equipment involved in liquid waste removal operations, we used Equation (3). Considering that, during the operation, four valves, ten

�anges, ten gaskets, and one hose are used, the total fail-ure rate is the sum of each rate multiplied by respective quantities, which will reach the value of Pf = 6.63E-05. Equation (1) calculates the frequency of scenarios with small leakage due to equipment failure in the ³lling sec-tion of the Liquid Waste Removal Vehicle, and considers a radioactive liquid factor forming a puddle (ALVES et al. 2013), like 0.792, as follows:

fc = 33.556E-05/year × 6.63E-05 × 0.792 = 1.76E-08/year (3)

From Tables 2, 3 and 4, it can be observed that the said accidental scenario has an improbable frequency and low severity. With regard to risk, it is classi³ed as “insigni³cant”.

�e basic probabilities of human errors (pEH) were taken from the tables in Chapter 20 of the NUT/CR-1278 reg-ulation, by the Nuclear Regulatory Commission (NRC) (SWAIN; GUTTMANN, 1983). To calculate the frequen-cies involving these probabilities, the event tree shown in Figure 2 was used, in which the focus was only on the general procedures of CBRNDefSys-BN (CBRN-Itaguaí Defense Battalion Reaction Group) when a scenario is postulated

Figure 2. Event tree of the general procedure failure frequencies of the Chemical, Biological, Nuclear and Radiological Defense System.

1 fc(1 – pA)(1 – pB)(1 – pC)

2 fc(1 – pA)(1 – pB)(pC)

3 fc(1 – pA)(pB)(1 – pC)

4 fc(1 – pA)(pB)(pC)

5 fc(pA)(1 – pB)(1 – pC)

6 fc(pA)(1 – pB)(pC)

7 fc(pA)(pB)(1 – pC)

8 fc(pA)(pB)(pC)

I – Radioactive liquid waste leakage

A – Switching on the CBRNDefSys-BN

B – Readiness/displacement of personnel involved

C – Reconnaissance/isolation/assembly of decontamination station

Sequence/FrequencyI A B C

Table 5. Number of SN-BR maintenance periods throughout its useful life.

Maintenance Period Quantity

RMP 35

RDP 4

RDP with a fuel chance 4

GMP 3

FDP 1

RMP: Routine Maintenance Period; RDP: Routine Docking Period; GMP: General Maintenance Period; PDF: Final Docking Period.



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in the PHA, including: system activation; readiness and displacement of the Reaction Group; and reconnaissance activities — isolating the area and assembling the local decontamination station with personnel and material. For calculations, the procedures were assumed to be performed with likely delays, where pA, pB and pC are the failure prob-abilities for the respective events.

As an example, human error was considered to take a delay of up to ten minutes in each stage of the event tree, where pA = 0.5, pB = 0.5 and pC = 0.05. �us, for the previously calculated scenario, if human error is applied, we arrive at a new frequency for the said scenario (Equatioo 4):

fc = 1.76E-08 × 0.5 × 0.5 × 0.95 = 4.18E-09. (4)

In total, 26 accident scenarios with radioactive liquid waste leakage in the PHA were classi³ed as shown in the risk matrix of Figure 3. �e scenarios were categorized according to risk before and after the activation of CBRNDefSys-BN.

�e results showed no change in risk categories, even with the sequence of human errors.

Considering the worst human-error hypothesis (sequence 8 of Figure 2) for CBRNDefSys-BN, the fre-quency of accident scenario was reduced. Events that were not performed by CBRNDefSys’ personnel in the correct order contributed to this reduction, so scenar-ios often classified as unlikely became very unlikely in PHA. However, if a scenario with human error occurs, the severity of the event will have a higher classification. Since the low severity turns to moderate, the delay in actions to mitigate the effects may cause greater dam-age to both the personnel and material (installations and equipment) involved, especially in situations of large leaks. These results are reflected in the risk matrix, as shown in Figure 3, where one can observe the increase in critical severity of three other scenarios. Without human error, events were classified as moderate, but four other situa-tions went from low to moderate.

Figure 3. Classification of accident scenarios according to the risk matrix adopted.

SEVERITY

Low Moderate Critical Catastrophic

FR

EQ

UE

NC

Y

Occasional 0 – 0 0 – 0 0 – 0 0 – 0

Likely 0 – 0 0 – 0 0 – 0 0 – 0

Unlikely 3 – 0 0 – 0 0 – 0 0 – 0

Very unlikely 5 – 0 3 – 3 0 – 0 0 – 0

Improbable 6 – 7 6 – 10 3 – 6 0 – 0

Risk categoriesNo human

errorHuman

error

Insignificant 23 23

Marginal 3 3

Moderate 0 0

0 0

0 0

Critical

Catastrophic



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Table 6. Accidental scenarios postulated with critical severity after the influence of human error.

Scenario with a large leakage of liquid waste

Cause Effect

An object falls on the hose, causing a guillotine cut with the feed pump on.

A puddle of liquid waste leakage is formed from the hose and the VRRL over the asphalt surface

of the docks, reaching the drainage network of the docks and exposing the personnel involved in the operation to the radiation.

An object falls on the hose, causing a guillotine cut with the feed pump on.

A radioactive cloud of the leaked liquid waste is

formed from fraction.

The explosion of the high-pressure compressed air pipe from the dock that has the pump connected cuts the hose into fragments.

A puddle of liquid waste leakage is formed from the hose over the asphalt surface of the docks, reaching the drainage network of

the docks and exposing the personnel involved

in the operation to the radiation

5. CONCLUSIONS

From the 26 postulated scenarios, the highest frequency occurred for cases with human errors related to forgetting to turn equipment on or o�, which took place in two pos-tulated scenarios whose frequency was 1.68 × 10-5/ year, but severity was low. All scenarios were categorized in the risk matrix of Figure 3, with 88.5% being classi³ed as insigni³cant and 11.5% =as marginal.

The probability of human error was then calculated with regard to general procedures of CBRNDefSys-BN. For the most frequent accidental scenario, when acti-vated by means of the event tree from Figure 2 and using the THERP technique, categories did not change in the risk matrix. However, there was an the severity of effects in scenarios went up, requiring that, when the facilities are fully operational, a PSA is performed to quantify these effects for scenarios reclassified as crit-ical and moderate severity with a large amount of liq-uid waste leakage.

Finally, importance is given to personnel readiness and training at CBRNDefSys-BN, along with a strong leadership role from the heads of the reaction group, so that procedural errors are minimized as much as pos-sible and undesirable consequences of radioactive leaks are avoided.

�is article depicted a safety analysis that will certainly be object of study for future safety guidelines of SN-BR ground support facilities.

�e in�uence of human error on accidental scenarios caused the severity of events shown in Table 6 to be reclas-si³ed as critical and should be subject to further probabilis-tic security analysis.

ALVES, A.S.M.; PASSOS, E.M.; DUARTE, J.P.; MELO, P.F.F. Radiological

Risk curves for the Liquid Radioactive Waste Transfer from Angra 1 to

Angra 2 Nuclear Power Plants by a Container Tank. In: INTERNATIONAL

NUCLEAR ATLANTIC CONFERENCE, 2013, Recife, PE.

AMARAL, L.A. Diretrizes Operacionais para a Postulação de Cenários

Acidentais de Instalações de Apoio em Terra para Submarinos de

Propulsão Nuclear. Dissertação (Mestrado) – Universidade Federal do

Rio de Janeiro, 2016.

BELLO, G.C.; COLOMBARI, V. The human factors in risk analyses of

process plants: the control room operator model TESEO. Reliability

Engineering, v. 1, p. 3-14, 1980.

REFERENCES

BIRKLER, J.; SCHANK, J.; SMITH, G.; TIMSON, F.; CHIESA,

J.; GOLDBERG, M.; MATTOCK, M.; MACKINNON, M. The U.S.

Submarine Production Base, An Analysis of Cost, Schedule and

Risk for Selected Force Structures. National Defense Research

Institute, RAND, 1994.

BRASIL. Ministério da Defesa. Marinha do Brasil. Estado-Maior

da Armada. Portaria nº 83 de 5 de maio de 2011. Dispõe sobre a

implantação do SistDefNBQR-MB. Brasília: Ministério da Defesa, 2011.

GUIMARÃES, L.S. Síntese de Doutrina de Segurança para Projeto e

Operação de Submarinos Nucleares. Tese (Doutorado) – Universidade

de São Paulo, São Paulo, 1999.



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LEWIS, E.E. Introduction to Reliability Engineering. Nova York: Wiley, 1996.

MEDEIROS, A.C. O Comando-Geral do Corpo de Fuzileiros Navais e

o Sistema de Defesa Nuclear, Biológica, Química e Radiológica da

Marinha do Brasil: os benefícios para a sociedade brasileira / CMG

(FN). Rio de Janeiro: ESG, 2014.

MRS ESTUDOS AMBIENTAIS. EIA-RIMA do Depósito Inicial – Depósito

2-B de Rejeitos Radioativos da Central Nuclear Almirante Álvaro

Alberto CNAAA e Prédio de Monitoração do Ativo Isotópico do CGR.

Brasília: MRS Estudos Ambientais, 2005.

REASON, J.T. Human Error. Nova York: Cambridge University

Press, 2000.

SWAIN, A.D.; GUTTMANN, H.E. Handbook of human reliability

analysis with emphasis on nuclear power plant applications,

NUREG/CR-1278. Washington, D.C.: U. S. Nuclear Regulatory

Commission, 1983.

U. S. NUCLEAR REGULATORY COMMISSION. NUREG-1624, Rev. 1.:

Technical Basis and Implementation Guidelines for a Technique for

Human Event Analysis (ATHEANA). Washington, D.C.: NRC, 2000.


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NAVAL ARCHITECTURE AND PLATFORMS

DEVELOPMENT AND INITIAL TESTS OF THE BRAZILIAN NAVY SUBMARINE FREE MODEL ML01

Desenvolvimento e ensaios iniciais do modelo livre de submarino ML01 da Marinha do Brasil

Hélio Correa da Silva Junior1, Walfrido Nivaldo Barnack Neto2, Leandro Pansanato3, Ricardo Sbragio4, Leonardo Pinheiro da Silva5, Fernando Moya Orsatti6

1. Master in Naval Engineering by the Escola Politécnica of the Universidade de São Paulo. Project manager of the Hydrodynamic Laboratory of the Navy´s Nuclear Development Board – São Paulo, SP – Brazil. E-mail: [email protected]

2. Undergraduate student in Mechanical Engineering by the Universidade Paulista. Mechanical technician of the Hydrodynamic Laboratory of the Navy´s Nuclear Development Board – São Paulo, SP – Brazil. E-mail: [email protected]

3. Graduate in Automation Control Engineering by the Universidade Estadual Paulista “Júlio de Mesquita Filho”. Subprojects Manager in Automation and Control Activities of the Hydrodynamic Laboratory of the Navy´s Nuclear Development Board – São Paulo, SP – Brazil. E-mail: [email protected]

4. PhD in Naval Engineering by the University of Michigan. Coordinator of the Hydrodynamic Laboratory of the Navy´s Nuclear Development Board – São Paulo, SP – Brazil. E-mail: [email protected]

5. PhD in Astrophysics and Space Techniques by the University of Toulouse III. Director of MODCO Engineering. Consultant of the Inertial Systems Laboratory of the Navy´s Nuclear Development Board – São Paulo, SP – Brazil. E-mail: [email protected]

6. Director of the MODCO Engineering. PhD in Electrical engineering by the Escola Politécnica of Universidade de São Paulo. Consultant of the Inertial Systems Laboratory of the Navy´s Nuclear Development Board – São Paulo, SP – Brazil. E-mail: [email protected]

Abstract: �e hydrodynamic tests needed for data collection of a submarine project are done with both free and captive models. �ese tests complement each other to obtain the maneuvering characteristics. For the free model, the development of the sys-tems that make it autonomous is necessary so that it can fol-low the speci³ed trajectory. �e development of this autono-mous underwater vehicle is a multidisciplinary project that invol-ves several ³elds of engineering. Besides its onboard systems, the free model demands the development of test methodologies, data collection, and analysis, so that the hydrodynamic coe¿cients of the equations that describe its trajectory can be determined and extrapolated to the full-scale submarine. In this paper, the charac-teristics and initial tests of the ML01 free model of the Brazilian Navy are presented.Keywords: Free model. Hydrodynamic coe¿cients. Maneuvering.

Resumo: Os ensaios hidrodinâmicos necessários ao levantamento de dados de projeto de um submarino são feitos tanto com mode-los cativos quanto com modelos livres. Ambos os tipos de ensaios se complementam para a obtenção das características de mano-brabilidade. No caso do modelo livre, é necessário o desenvol-vimento de sistemas que o tornem autônomo, de modo que ele cumpra a trajetória especi³cada. O desenvolvimento desse veículo submarino autônomo tem uma dimensão multidisciplinar, envol-vendo diversas áreas de Engenharia. Além dos sistemas de bordo, o modelo livre necessita do desenvolvimento de metodologia de ensaios, de aquisição e de análise de dados, de modo que os coe-³cientes hidrodinâmicos das equações que descrevem a sua traje-tória sejam obtidos e extrapolados com precisão para o submarino em escala real. Neste artigo, as características e os testes iniciais do modelo livre ML01 da Marinha do Brasil serão apresentados.Palavras-chave: Modelo livre. Coe³cientes hidrodinâmicos. Manobra.

Hélio Correa da Silva Junior, Walfrido Nivaldo Barnack Neto, Leandro Pansanato, Ricardo Sbragio, Leonardo Pinheiro da Silva, Fernando Moya Orsatti


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1. INTRODUCTION

�e design of a submarine involves intense experimen-tal validation to ensure that the operation requirements are satisfactorily achieved. �e performance of the vessel is tested through analytical programs, and in laboratories and physical systems. Among the laboratories and systems used in the hydrodynamics area for project data collection, there are towing and maneuvering tanks, the cavitation tunnel, and the free model.

In the towing tank, the tests allow to obtain the propulsive characteristics of the vessel as well as some hydrodynamic coefficients, operating with a captive model of the vessel in reduced scale, that is, the model is attached to a dynamometer and towed by a towing carriage. In the maneuvering tank, the models can be captive or free, and the tests aim to collect hydrodynamic and behavioral characteristics of the vessel at sea. In the cavitation tunnel, the operating characteristics of pro-pellers are measured. According to the dimensions of the cavitation tunnel, the propeller model can be tested in open water (without the hull attached, generating the wake) or positioned aft a ship model that directly gen-erates the wake incident on the propeller. Finally, the free model operates without any physical connection with another system, being completely autonomous. This model allows the obtaining of hydrodynamic coef-ficients. It can operate in a maneuvering tank as well as in lakes, in dams or in the sea, which demonstrates its great versatility. The hydrodynamic coefficients are the components of the equations of motion of a vessel at six degrees of freedom (these equations are described in Feldman, 1979) and they are necessary to reconstruct its trajectory. Determining them is essential to predict, during the design stage, the ability of a submarine to maneuver safely.

�e aforementioned facilities and systems complement each other to achieve the purpose of projecting an opti-mized and safe vessel. Some hydrodynamic coe¿cients can be accurately obtained in maneuvering or towing tanks operating with captive models, while cross-hydrodynamic coe¿cients are collected with free model tests, since they depend on movements at six degrees of freedom, which are not possible in captive models.

�is article presents the development of a test platform of great versatility: the submarine free model — an auton-omous submarine vehicle, with the objective of collecting hydrodynamic data. The construction of the free model encompasses design, fabrication, assembly, systems integra-tion, and hydrodynamic performance tests. �eir preparation and operation involved the joint work of multidisciplinary teams of the Brazilian Navy.

2. OBJECTIVES OF THE FREE MODEL

�e free model ML01 consists of a common core unit, which consists of a pressure resistant hull in which elec-tronic equipment, propulsion, and sensors are boarded, and of a hydrodynamic hull built according to the type of ves-sel that one wishes to test. �us, the common core can be adapted to several types of hull, both for submersible vehi-cles and surface ships.

�e objectives of free model development and tests are:1. Hydrodynamics:

• Obtaining hydrodynamic coe¿cients of the equations of motion of a vessel;

• Execution and acquisition of data of typical vessel maneuvers: straight line navigation, turning circle, zig-zag maneuver, spiral and any other maneuver deemed necessary;

• Validation of design methodology and analysis of conventional or ducted propellers;

• Performing cavitation check on propellers.2. Acoustics:

• Veri³cation of noise radiated by propellers;• Veri³cation of hull hydrodynamic noise radiated by

the hull;• Development of special equipment tests (e.g.: acous-

tic modem, hydrophones, pinger, small sonar, etc.).3. Logical systems:

• Development of government control and depth systems;• Development of inertial systems;• Development of data analysis methodologies.

4. Structural mechanics:• Development of design and analysis methodologies

of pressure vessels.



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5. Computational simulation:• Training in the use of CAD, CFD, and FEM softwares.

6. Manufacturing and assembling:• Machining of complex components (rudders, propeller);• Training in assembly and integration of onboard

systems.

�e versatility of the free model project allows its use in other types of missions, such as, for example, monitoring, provided its structural strength characteristics of the resis-tant hull are respected.

In its current con³guration, the free model measures 6.77 m in length and weights 1,200 kg, without ³xed bal-last (Figure 1).

3. RESISTANT HULL

�e resistant hull of the free model is considered a com-mon core, which can be disassembled and adapted for sev-eral types of vessels (Figure 2). It consists of ³ve sections (Figure 3), made of 5052F naval aluminum. �e total length of the resistant hull is 4.60 m.

�e ³rst section, at the bow of the vessel, can be freely �ooded when necessary. �is is where the bow trimming and ballast tanks are installed. �ey act on the maintenance of the neutral buoyancy and to trim the model (along with the stern trimming and ballast tanks).

The second section is that of control electronics. Auxiliary batteries, the inertial measurement unit (IMU), and

Figure 1. Free model ML01 maneuvering in the area of the Instituto de Estudos do Mar Almirante Paulo Moreira (March 2017).

Figure 2. Preparation of the resistant hull for watertightness tests in the towing tank of Instituto de Pesquisas Tecnológicas.

Figure 3. Resistant hull, ballast tanks, and shaft line sections.

7

6 5 4 3 2 1

1. Bow trimming and ballast tanks section2. Electronics section3. Propulsion batteries section4. Frequency inverter section

5. Electric motor section6. Stern trimming and ballast tanks7. Shaft line



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the guidance computer are located in this section. �e IMU, the computer, and their control and interface systems were autochthonous developments to be used in the free model.

�e third section is that of propulsion batteries, which are commercial rechargeable lead-acid batteries.

�e fourth section is that of the frequency inverter, which controls the speed of motor rotation through guidance com-puter commands.

�e ³fth section is that of the electric motor. Both the frequency inverter and the electric motor are commercial industrial equipment.

�e stern trimming and ballast tanks are at the rear of the resistant hull.

Sections are sealed by o’rings, and the shaft output uses a mechanical seal.

4. HYDRODYNAMIC HULL

�e material of the hydrodynamic hull is ³berglass. A CNC lathe machined the mold for the hull in wood (Figures 4 and 5). �e hull is screwed into metal support brackets glued to the resistant hull. It has no requirements for structural resistance to pressure when submerged and, therefore, allows for free circulation of water on the inside. �e hydrodynamic hull is divided into bow hull, stern hull, superstructure, and sail.

5. TRIMMING AND BALLAST SYSTEM

�e trimming and ballast system (Figure 6) consists of four tanks, two in the bow and two in the stern. �e bow trimming and ballast tanks are in section 1, while the stern trimming and ballast tanks are outside the resistant hull in the back of section 5, encircling the axis line (Figure 3). �e onboard computer uses information from the IMU and pressure sen-sors to control the system. �e tanks have compressed air or sea water inlet and outlet valves. Compressed air cylinders pressurize the tanks in case there is the need to drain water.

6. GUIDANCE, NAVIGATION, AND CONTROL SYSTEM

�e guidance, navigation, and control system is respon-sible for implementing the route that the free model must

Figure 4. Hydrodynamic hull mold (stern) for fiberglass hull manufacture.

Figure 5. Stern Hydrodynamic hull, made of fiberglass applied on a wood mold.



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Watertight compartment

Port trimmingand ballast

tank

Starboard trimming

and ballast tank

Compressed air

Figure 6. Scheme of the trimming and ballast system (bow and stern).

follow, for estimating position and attitude, and for de³ning the commands to be transmitted to the actuators. It con-sists of an IMU, an onboard computer, a human-machine interface, hydrostatic pressure sensors, and actuators (rud-ders and engine).

�e IMU has accelerometers and gyroscopes. Accelerometers record the accelerations of the model, and gyroscopes, the angular velocities. �e information is obtained at six degrees of freedom, making it possible to recover the movements of the free model.

�e onboard computer boards the control software and acts on the system with programmed commands. Moreover, it records information on the accelerations and

velocities from the IMU, for later data extraction and tra-jectory acquisition.

Pressure sensors measure the pressure in the bow and stern regions, feeding IMU estimates with the depth and attitude of the model.

The human-machine interface allows the communi-cation between the operator and the free model, feeding the control software with data on engine rotation, head-ing, steering angles, and maneuver parameters. It also enables data recovery and analysis after the maneuver is over. When on the surface, telemetry with a radio link provides both the initial commands of a maneuver and data acquisition.



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7. ELECTRICAL SYSTEM

�e electrical system is divided into auxiliary and propulsion.�e auxiliary electrical system feeds the free model hotel

load with 48VDC. It consists of four rechargeable lead-acid batteries like those of the propulsion. �e charging system is independent.

�e electrical propulsion system operates with rechargeable lead-acid batteries with enough autonomy for tests during a one-day operation, at moderate speeds (Figure 7). �e out-put voltage of the battery pack is 312VDC.

�e free model has two magnetic switches, one in the bow and another in the stern. As a safety measure, the removal of any of the switches shuts o� the electrical propulsion system of the free model. �e auxiliary electrical system is only turned o� by removing the speci³c magnetic switch from this system.

8. SENSORS AND ACTUATORS

�e sensors installed in the free model are:1. Pressure sensors: there are two pressure sensors, one

located on the bow and another on the stern. �ese sensors

record the depth of the vessel so that the control system can trim the free model before starting the test. After the start of the test, the pressure sensors register the depth of the operation and collect data to activate the safety system that can bring the free model back to surface, if necessary;

2. GPS: the GPS is located on the sail. It records the speed or the free model in maneuvers in the surface;

3. Hydrophones: Located in the stern, they register the noise of the free model, so as to make it possible to compare the modi³cations on both the hull and the propeller.

�e free model has the following actuators:1. Electrical engine controlled by frequency inverter;2. Vertical rudder (upper and lower);3. Horizontal stern rudders (port and starboard); 4. Horizontal sail rudders (port and starboard).

�e rudders are activated two by two (port/starboard or upper/lower) by a system consisting of servomotor, reducing gear, and transmission belts.

9. PROPULSION

Propulsion consists of a commercial electric engine of 12,5 HP, controlled by a frequency inverter.

�e shaft line has a �exible coupling just after the engine and mechanical seal at the outlet of the resistant hull. �ree bearings in the hydrodynamic hull region sup-port it (Figure 8).

�e lifting-line and the lifting-surface theories were the basis for the design of the propeller. �ey operate in an interactive and integrated way to obtain a propeller con³guration that provides the desired thrust and opti-mizes e¿ciency.

In the lifting-line theory (LERBS, 1952), a vortex line models the blade of the propeller. �is line has an appropri-ate circulation distribution which generates the lifting force. In the wake, the emitted vortices are modeled as equally spaced helical vortices, with constant pitch angle. �ese wake vor-tices generate induced speeds on the blade, which are taken into consideration when calculating the pitch angle of the blade. �us, pitch angles, speeds, and circulation distribution Figure 7. Propulsion batteries section.



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Figure 8. Motor and shaft line.

24 3

1

6 5

1. Electric motor2. Flexible coupling

3. Mechanical seal4. Bearing

5. Bearing6. Bearing

of the blades are obtained and used as input data in the lift-ing-surface theory.

�e lifting-surface theory (KERWIN, 1973) discret-izes the geometry of the blade radially and angularly in a mesh of distributed vortices that generate lift force and of sources that simulate the thickness of the blade. �e sources, the blade vortices, and the helical vortices emitted on the propeller wake generate the induced velocities in the blade, which are composed with the rotation and with the advance speed to obtain the pitch angle. �e lift force is obtained by the integration of the pressures on the blade surface, which generates thrust and torque. �is procedure results in the ³nal geometry of the propeller, providing the necessary thrust to propel the vessel.

Unlike propellers designed by systematics series, obtained in open water tests using a mean value of axial wake, the pro-peller designed with this method considers the radial distri-bution of the axial wake generated by the hull. �e complete hull of the free model was simulated in the Computational Fluid Dynamics (CFD) code Ansys Fluent to provide this wake. �e mesh used 21,36 million elements. �e turbu-lence model employed was the k – ω SST. �us, the propel-ler is designed to operate in the stern of a speci³c hull and is adapted to the wake generated by that hull, improving its performance.

�e maximum propeller speed is 1,250 rpm, requiring approximately 11 BHP and providing a thrust of the order of 118 kgf, enough to reach 12 knots of speed. �e pro-peller e¿ciency estimated in the project is 0,626, with the propeller operating aft of the hull on the wake obtained

by CFD simulation. �e material of the propeller is naval bronze. �e distribution of circulation used was the opti-mal distribution, as de³ned by Lerbs (1952). �e propeller was designed with quadratic skew angle distribution and 20º skew at the blade tip.

10. INITIAL TESTS

In order to evaluate the free model at sea, straight line navigation, turning circle, and immersion and emersion with rudders from the surface tests were carried out at Instituto de Estudos do Mar Almirante Paulo Moreira (IEAPM), in Arraial do Cabo.

�e dimensionless coe¿cients that control the �ow dynamics in submerged tests of the free model are the numbers of Reynolds, Froude, and Strouhal. In addition, it is important to analyze the dependence of the depth-di-ameter H/D ratio.

�e Reynolds number relates inertial and viscous forces, and its equality between model and full scale is not possi-ble. It controls viscosity-related e�ects, such as friction and turbulence. Equation 1 presents the Reynolds number, in which U is the speed of the vessel, L is the length, and v is the kinematic viscosity.

Re = ULv (1)

�e Froude number relates inertial and gravitational forces. Consequently, it controls the e�ects of wave formation and



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hydrostatic restoration. Even with the free model in depths of no proper wave formation, it is necessary to equal the Froude number when analyzing restoration e�ects, as in turning cir-cle tests and hydrodynamic coe¿cient survey. Equation 2 presents the Froude number, in which U is the speed of the vessel, g is the acceleration of gravity, and L is the length.

Fr = gLU (2)

�e Strouhal number relates variable and inertia forces. During maneuvers, the angular speeds in row, pitch, and yaw (p, q or r) are not constant, showing variations in time t (SHEN and HESS, 2010). �us, there are variable forces and moments resulting from oscillatory movements of the model. �ese e�orts are characterized by the Strouhal number, rep-resented in Equation 3, in which ω(t) is the rotation speed in one of the three coordinate axes, L is the length, and U is the speed of the vessel.

St = , ω = p, q ou rω(t)LU

or r (3)

�e depth-diameter ratio determines the maximum speed of the test with no wave formation, which is closely related to the Froude number.

10.1. STRAIGHT LINE TESTSStraight-line navigation tests aim to determine the pro-

pulsive power as a function of speed. In order to have simi-larity to the full-scale vessel, the �ow needs to be turbulent. �e corresponding dimensionless quantity is the Reynolds number, related to �ow turbulence, and it is impossible to maintain equality to the full scale. �e di�erence between the Reynold number of the vessel and that of the model will originate scale e�ects in test results. If the Reynolds number of the model is above 10 million (SHEN; HESS, 2010), these e�ects are reduced. By adopting the value of 10 million as the smallest Reynolds number in which the free model will operate, one obtains the minimum test speed of 1,5 m/s.

�ere is no need to equal the Froude number for sub-merged tests that verify the propulsion power in a straight-line navigation. �is dimensionless quantity compares iner-tia and gravitational forces related to wave formation. It is important to ensure, however, that no waves are formed during

tests. �us, the relation between the depth of the test and the diameter of the hull shall be one that avoids wave formation for a given Froude number.

CFD simulations showed that there is no wave forma-tion for speeds between 1,5 and 3 m/s — typical in tests — if the ratio between test depth and free model diameter is above 4,8. For higher speeds, the free model must operate at greater depths.

In straight-line tests, angular speeds are null or reduced, so that there is no need to equal the Strouhal number.

Based on the results of straight-line tests, one can ³nd the power of the free model as a function of speed. �e col-lected data allows to obtain or con³rm design parameters such as the form factor of the hull (used to calculate the friction resistance of the vessel) or the thust reduction fac-tor (which considers the e�ects of propeller operation in the increase of the ship resistance). It also validates the method of the propeller design.

10.2. MANEUVERABILITY TESTS�e purpose of maneuverability tests is to determine char-

acteristics of directional stability, tactical diameter, and hydro-dynamic coe¿cients for the equation of motion. As observed in straight-line tests, the minimum Reynolds number should be 10 million, with its corresponding speed.

In this type of test, the Froude number must be equaled, even with the free model submerged, due to pitch and roll movements in the model, which create restauration moments dependent on the acceleration of gravity.

As in straight-line tests, we must respect the ratio between test depths and diameter as a function of the Froude number to prevent wave formation.

Lastly, it is desirable to have an equaled Strouhal num-ber in maneuverability tests, to obtain dynamic similarity in the movement of the vessel in full scale, due to the emission of vortices that generate alternate forces during this type of test. �e equaled Strouhal number occurs directly by the imposition of the following factors:1. Froude equality;2. Vertical position of the center of gravity (CG) in scale;3. Inertia in scale.

It is rather di¿cult to ensure that the inertias of the free model and of the full-sized vessel are on scale. �is would



| 18 |

require mass distribution of internal equipment, which is not feasible in practical terms.

To obtain the hydrodynamic coe¿cients, which are a function of the shape of the hull, this equality is not strictly necessary, though it is important to know the values of the inertia for the free model so that the equations are com-posed correctly.

Figure 9 presents the results of a turning circle test of the free model with 312 rpm and maximum rudder angle. �e trajectory is estimated from the movement data recorded by the IMU.

10.3 IMMERSION AND EMERSION TESTS

The immersion and emersion test with rudder angle intended to test the capability of the free model to simulate emergency maneuvers. With a slightly positive buoyancy, the free model submerged with maximum horizontal rud-der angle (beginning of the maneuver in Figure 10). Past a speci³ed depth, the rudder was reversed, moving toward the surface. �e maneuver was recomposed by IMU and pressure sensors data, according to Figure 11. Both immersion and

emersion occurred with angles of approximately 45º, reach-ing a maximum depth of 12 m.

Figure 12 presents the end of the maneuver, with the free model reaching the surface.

11. CONCLUSION

The free model is an autonomous submarine vehicle of great versatility and whose main purpose is to perform

Figure 9. Plot of the turning circle test, as registered by the Inertial Measurement Unit. Free model at 312 rpm and maximum rudder angle for the port. The test lasted 180s, with the duration of the maneuver after the rudder action being 150s.

y

x

Figure 10. Beginning of the immersion maneuver from the surface.

Figure 11. Attitude and depth during immersion and emersion maneuvers recomposed with the Inertial Measurement Unit and pressure sensors data.

Acceleration and beginning of

immersion

Rudder angle inversion

Beginning of emersion after

maximum depth

Free model reaching the

surface

Emersion



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Figure 12. End of immersion and emersion maneuver.

�e free model performed turning circle, straight-line navigation, and immersion and emersion maneuvers in the ³rst tests, which were intended to verify the operation capa-bility of the free model. �e results fully corroborate the objectives of the tests.

12. ACKNOWLEDGEMENTS

�e tests and the safe operation of the free model require an appropriate infrastructure, which was made possible thanks to the e�orts and professionalism of the teams of Centro Tecnológico da Marinha em São Paulo (CTMSP), Diretoria de Desenvolvimento Nuclear da Marinha (DDNM), Centro Industrial Nuclear de ARAMAR (CINA), Instituto de Estudos do Mar Almirante Paulo Moreira (IEAPM), Base Almirante Castro e Silva (BACS), Base Aérea Naval de São Pedro da Aldeia (BAeNSPA), and Instituto de Pesquisas Tecnológicas do Estado de São Paulo (IPT).

FELDMAN, J. DTNSRDC Revised standard submarine equations of

motion: DTNSRDC/SPD-0393-09. Bethesda: David W. Taylor Naval

Ship Research and Development Center, jun. 1979.

KERWIN, J.E. Computer Techniques for Propeller Blade Section

Design. International Shipbuilding Progress, p. 227-251, 1973.

REFERENCES

LERBS, H.W. Moderately loaded propellers with a finite number of

blades and an arbitrary distribution of circulation. Transactions of the

Society of Naval Architects and Marine Engineers, v. 60, p. 73-123, 1952.

SHEN, Y.T.; HESS, D.E. An experimental method to satisfy dynamic

similarity requirements for model submarine maneuvers. Journal of

Ship Research, p. 149-160, set. 2010.

hydrodynamic tests. It consists of a common core, which can be used in various types of vessel con³guration, both surface ships or submarine ones, as well as in numerous types of mis-sions. Its design, manufacture, and operation involve several specialties, enabling the necessary training and technolog-ical development for future projects by the Brazilian Navy.


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CLINICAL ENGINEERING AS AN AGENT FOR IMPROVING THE

QUALITY OF MEDICAL CAREA engenharia clínica como agente de

melhoria da qualidadedo atendimento médico

Glauco Barbosa da Silva1, Nival Nunes de Almeida2

1. Frigate Captain. D.Sc. in Production Engineering. Researcher at the Center for Marine Systems Analysis (CASNAV) - Rio de Janeiro, RJ - Brazil. E-mail: [email protected], [email protected]

2. D.Sc. in Electrical Engineering. Full Professor at the Naval War School (EGN) - Rio de Janeiro, RJ - Brazil. E-mail: [email protected]

Abstract: �is study aims to present clinical engineering as an alter-native to support quality improvement in Medical Care at healthcare facilities of the Brazilian Navy (EAS-MB). �e evolution of health technologies incorporated into medical equipment and systems (ESMH) has further complicated the management of EAS-MB, requiring experience and di�erent skills. Based on a literature review, concepts, history and tasks of clinical engineering professionals are presented, uncovering its potential and adherence to improve patient safety and care. �e structure of the Navy Health System is analyzed, seeking to identify any gaps between the activities of con-trol institutions and the technical execution that clinical engineering procedures can reduce, contributing with an improvement in patient care. �e Odontoclínica Central da Marinha (OCM) was a point of interest, since it acts on the specialized care axis. �e analysis shows the existence of gaps in the management of the ESMH life cycle that can be explored with the proposed approach.Keywords: Biomedical Engineering. Clinical Engineering. Medical Care.

Resumo: O objetivo deste trabalho foi apresentar a engenharia clínica (EC) como alternativa para a melhoria da qualidade do atendimento aos pacientes em estabelecimentos assistenciais em saúde da Marinha do Brasil (EAS-MB). A evolução das tecno-logias em saúde incorporadas aos equipamentos e sistemas médi-co-hospitalares (ESMH) tornou ainda mais complexa a gestão dos EAS-MB, requerendo experiências e habilidades de diferen-tes áreas. A partir de uma pesquisa bibliográ³ca, os conceitos, o histórico e as atribuições dos pro³ssionais da EC são apresenta-dos, revelando sua potencialidade e aderência com a melhoria da segurança e do atendimento aos pacientes. A estrutura do Sistema de Saúde da Marinha é analisada buscando identi³car eventuais lacunas entre as atividades dos órgãos de controle e técnicos de execução que possam ser reduzidas por medidas de EC, concor-rendo para uma melhoria no atendimento aos pacientes. Por ³m, a Odontoclínica Central da Marinha (OCM) foi analisada por atuar no eixo de atenção especializada. O resultado da análise aponta a existência de gaps na gestão do ciclo de vida dos ESMH que podem ser explorados com a abordagem proposta.Palavras-chave: Engenharia Biomédica. Engenharia Clínica. Atendimento ao Paciente.

Glauco Barbosa da Silva, Nival Nunes de Almeida


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1. INTRODUCTION

In the last decades, medicine and public health care have changed radically. The increasing technological developments have led to changes ranging from the inclusion of modern equipment and systems in preven-tion, diagnosis and treatment of diseases to the rehabil-itation of patients.

In the ³eld of diagnosis, technological innovations have enabled the early detection of diseases, such as positron emis-sion tomography scanners, nuclear magnetic resonance, scin-tigraphic camera, among others.

�e signi³cant advances in the support to the diverse services presented in health care establishments (HCE), arising from the use of new resources, are directly related to the increasing complexity and reliance on these systems and equipment.

On the other hand, due to the reliance on technolog-ical resources, the occurrence of malfunction or failures in equipment and in medical and hospital systems (MHS) can represent a high cost, not only in material terms, but also in socially, by interrupting patient care. In extreme cases, lead-ing to death.

�e concern for patient safety prioritizes the operational availability of MHS, and careful preparation of technical requirements and maintenance procedures that are both e¿-cient and e�ective, based on the availability and reliability of these MHS, becomes indispensable.

Faced with this scenario of MHS incorporation with high added value, HCE management has reached a greater level of complexity, since it involves scarce ³nancial and human resources and high demands from the patients. �e lowest possible cost without damaging the quality of care provided (BRASIL, 2013).

In addition to the management challenges, another important aspect of the use of MHS is over diagnosis, due to the indiscriminate use of new technologies, which may suggest early treatment. Apart from the risk involved, such a procedure burdens the health system (TOSCAS; TOSCAS, 2015).

Considering these many con�icting aspects, an import-ant question arises: how to manage di�erent skills involv-ing critical aspects of medical care, health technology, procedures and maintenance routines for MHS, ³nancial

and human resources, among others, in the search of bet-ter patient care?

In biomedical research, researchers are engaged in expand-ing knowledge to ³nd ways to prevent health problems and to develop bene³cial products, medications, and procedures to treat and cure diseases and conditions that cause disease and death in living organisms (California Biomedical Research Association — CBRA, 2015).

�e contribution and participation of researchers with dif-ferent backgrounds and abilities (multidisciplinarity), such as physicians, veterinarians, computer scientists, engineers, techni-cians and researchers in general, are requirements of biomedical research, combining di�erent ³elds of science (CBRA, 2015).

In this context, clinical engineering (CE) presents itself as a potential tool for supporting the rational use of health technologies and for improving patient care.

For the theoretical basis of this study, a bibliographic research on the topic “clinical engineering” was carried out in the main scientific databases (Capes, Scopus, Web of Science, ResearchGate journals). �e selection and analysis of the documents collected were based on concepts of bib-liometrics, which made it possible to identify the most rele-vant publications available in the literature.

�is study aims to present Clinical Engineering as an alternative to support the improvement in quality of care in health care establishments of the Brazilian Navy (EAS-MB). To achieve this goal, the following structure is presented: in section 2, the concepts of biomedical and clinical engineering and the structure of medical-hospital care are presented to the military and their dependents within the BN; Section 3 presents how these concepts can be applied to the BN; end-ing with a conclusion.

2. CONCEPTS AND DEFINITIONS

2.1. BIOMEDICAL ENGINEERING�e objective of biomedical engineering is the appli-

cation of methodologies and technologies from physi-cal sciences and system engineering with emphasis on the diagnosis, treatment and prevention of diseases in men (SAWHNEY, 2007), representing one of the fast-est growing branches of industry in the developed world (SHELLENBARGER, 2010).



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From the review of the scienti³c literature by Pereira, Gonçalves and Almeida (2010), the main thematic areas identi³ed in biomedical engineering were classi³ed as: bio-logical signal processing; ultrasound applied to medicine; proteomics; genomics and bioinformatics; nervous and muscular system; technological evaluation in health; clinical engineering; biomechanics of motion; rehabilitation engi-neering; medical imaging; arti³cial intelligence and neural networks; arti³cial organs and biomaterials; biotechnology, among others.

2.2. CLINICAL ENGINEERING AND THE IMPROVEMENT OF PATIENT CARE

CE is a sub-area of biomedical engineering which, based on concepts from practically all areas of engineering, han-dles the processes and technical and managerial aspects involving the safe and e¿cient operation of medical systems and equipment in a hospital environment (ZAMBUTO, 2004). �e safe operation of MHS can be characterized as the permanent attention to preventive maintenance, cal-ibration and analysis of electrical installations (SOUZA et al., 2014).

�e beginning of CE occurred in the Armed Forces of the United States of America (USA) in 1942, with the course of maintenance of medical equipment. In the 1960s and 1970s, with the evolution of technologies and rising costs, aggravated by the news of death of patients caused by electric shock related to medical equipment, engineers were encouraged to enter hospitals and clinics to maintain the new health care technologies (TERRA et al., 2014; RAMIREZ; CALIL, 2000).

�e insertion of CE in the hospital environment quickly allowed for the identi³cation of electrical safety failures in electromedical equipment, and the fact that some devices operated outside manufacturers’ speci³cations. In general, the problems identi³ed were caused by lack of maintenance or even equipment malfunctions (TERRA et al., 2014).

It should be noted that a calibration error, for example, can lead to misdiagnosis, exposing the patient to unnecessary treatments and, in extreme cases, leading to death.

Other changes resulting from the inclusion of CE were the creation of rules and regulations for the safe operation of equipment and new speci³cations that pressured the market to improve the equipment (TERRA et al., 2014).

In Brazil, debates on the topic expanded after the 1980s with the participation of researchers in international meet-ings, the exchange of information and collaboration agree-ments. However, the lack of skilled labor was a serious issue to be solved. In this period, a USD 1 billion waste was esti-mated because of the deactivation of medical equipment due to lack of repair, spare parts, supplies and installation (TERRA et al., 2014), a scenario that persists in HCE throughout the country.

In 1992, because of the need to re-equip public hospi-tals, the demand for clinical engineers arised and, since 1993, Brazilian universities have begun to train these professionals. However, it was only on October 16, 2003, that the Brazilian Association of Clinical Engineering was founded (TERRA et al., 2014; BRASIL, 2015a).

�e clinical engineer is a professional quali³ed to apply engineering techniques in the management of health equip-ment, enabling the traceability, usability, quality, e¿ciency, e�ectiveness, safety and performance of this equipment in order to guarantee patient and user safety (BRASIL, 2015a).

Terra et al. (2014, p. 49) state that “the presence of clin-ical engineers not only ensured a safer environment, but facilitated the use of the latest medical technology, improv-ing patient care.”

Figure 1 shows the various interactions between CE and health system factors, allowing a quick visualization of the complexity of actions to which the sector is subject, since it requires multidisciplinary knowledge.

According to Wada (2010), in an HCE, among other responsibilities, clinical engineers are responsible for:• directing, managing, coordinating and technically orient-

ing CE services;• controlling the assets of medical-hospital equipment and

its components;• assisting in the acquisition and acceptance of new

technologies;• training personnel for maintenance (technicians) and

operation (operators) of equipment;• designating, elaborating and controlling preventive/cor-

rective maintenance contracts; carrying out preventive and corrective maintenance activities on medical-hospi-tal equipment within the HCE;

• controlling and monitoring outsourced maintenance services;



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• establishing control and safety measures within the hos-pital environment (MHS);

• developing new or modi³ed MHS projects;• establishing procedures to extend the lifecycle of MHS;• implementing and controlling the quality of MHS mea-

surement, inspection and testing equipment;• calibrating and adjusting the MHS;• assessing the obsolescence of MHS;• presenting productivity reports on the management

and maintenance of MHS – quality and/or productivity indicators.

One of the responsibilities of the CE sector is the man-agement of the lifecycle of an MHS, which will be described next due to its strong impact on patient treatment/care, thus highlighting the performance of the CE.

Studies by the World Health Organization (WHO) in developing countries show that equipment ine¿ciency sig-ni³cantly a�ects the provision of health care services and that inadequate management is the main cause of inoperability, and the problem is aggravated in the absence of an equipment acquisition policy (MORALES; ENSSLIN; GARCIA, 2007).

�e life cycle of an MHS is basically composed of three phases: incorporation, use, and renovation/discontinuation. �e main activities of each phase are described below.

The incorporation phase comprehends the process of surveying requirements and technical speci³cations. In this phase, the structure of the place that will receive the equip-ment must be considered; the need for changes in building infrastructure, hydraulic, refrigeration and electrical instal-lations must also be evaluated.

In practice, it is not uncommon to incorporate MHSs that are incompatible with the installation environment, causing an unintended addition to the project and causing service unavailability and consequent harm to patients in need of care.

Once the technical speci³cations have been de³ned, the incorporation phase is followed by the evaluation of the MHSs available in the market. Among the options pro-vided, it is important to be aware of the direct and indirect costs: existence of diagnostic software, maintenance costs, manufacturer support, extended warranty service, proxim-ity to technical assistance, technical training, documenta-tion and technical/user manuals, spare parts and calibration

ClinicalengineerCosts and

savings

Technical requirements

and reliability Operation

Accepted

medical

practice

Human

engineering

Maintenance and

safety of power

and cabling

Planning for

the futureSafe a

nd ac

cepte

d

med

ical p

ract

ices

Medical requirements

Salesman Nurses Physicians

Hospital administration

Public/private agreements

Development agencies

Regulatory agencies

Clinical research

Hospital environment

Health supporting professionals

Patients

Source: Terra et al. (2014).

Figure 1. Clinical engineering interfaces.



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equipment. In addition, operational and shutdown costs, depreciation and quality of service should be considered (BRASIL, 2002).

Once the most appropriate MHS has been selected, the next activity is the installation, which can be carried out by the manufacturer or by an accredited company, and must be monitored by the CE sector in order to guarantee its cor-rect execution. At this stage, it is best to perform technical and operational training of the professionals who will be in contact with the equipment. �e content, type, quantity and duration of training are de³ned by the CE sector in the acquisition process.

�e importance of training is owed to the fact that most of the equipment problems that cause downtime stem from inadequate operation. �e incorporation phase ends with the reception of the equipment/system.

In the use phase, retraining and equipment training should be planned for teams, since con³guration errors or lack of previous user information are common.

Planning of equipment maintenance, whether preventive or corrective, is necessary. In this activity, the type of main-tenance to be adopted must be de³ned.

In general, corrective maintenance is not anticipated and may occur at any time during the equipment’s life-cycle. However, there are maintenance models with fail-ure predictability that allow the recognition of standards and estimation of the occurrence of a failure or malfunc-tion. Among these, the Reliability Centred Maintenance (RCM) model of the North American aeronautical indus-try, which aims to increase the safety and operational avail-ability of the equipment and the reduction of costs, stands out (MOUBRAY, 2001).

�e RCM relies on a broad statistical analysis of fail-ures, since in complex equipment, unless there is a domi-nant failure mode, scheduled revisions have little e�ect on reliability. In addition, many systems do not have an e�ec-tive form of scheduled maintenance (NEVES; GARCIA; NEVES, 2001).

�e advantages of adopting the model depend on its con-tinuous monitoring and feedback, since it is based on past information. Failure history is an input for statistical anal-ysis to be performed. Another important point is that the RCM should be directed to critical equipment and not rec-ommended for all equipment and systems.

According to Moubray (2001), seven basic questions guide the RCM implementation process:• What are the functions and performance standards of an

asset in its current operational context?• How can it fail to ful³ll its missions?• What causes each functional failure?• What happens when each failure occurs?• How does each failure matter?• What can be done to prevent each failure?• What should be done if an appropriate preventive task is

not found?

In the case of equipment with high maintenance cost, not critical or in which preventive/corrective mainte-nance is required in the short term, the outsourcing of services is a possibility to be considered. Preceding the outsourcing of maintenance services, an important activ-ity, belonging to the use phase, is the management of maintenance contracts.

�e renewal or discontinuation phase is the last phase of an MHS’s lifecycle, which can be terminated due to: time of use (or obsolescence); undue and irreparable use; and technology disuse (DAVID, 1985).

�e discontinuation of an MHS requires intervention from the CE sector, responsible for generating technical reports that justify the end of the equipment’s lifecycle. �e disposal of the equipment complements the discontinua-tion activity. At the end of the lifecycle, the lessons learned during the process should be used as input for the incorpo-ration of new MHSs.

�e main activities pertaining to each stage of the lifecy-cle of an MHS are summarized in Chart 1.

Once the MHS’s lifecycle phases are described, Medeiros (2015) presents a model for the classi³cation of the equip-ment regarding: function, risk and need for maintenance. From the combination of these factors, f (functionality, risk, maintenance), the equipment management (EM) indicator is obtained by adding the score assigned to each classi³ca-tion within the factor, and serves as a suggestion as to which equipment should or should not be under the responsibility of the CE sector.

�e function factor refers to the functionality of the equipment and can be classi³ed as: therapeutic, diagnos-tic, analytical or others. �e risk factor is related to the



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risk to which the patient or user is exposed during the use of the equipment, being maximum when it can lead to death. �is factor can be classi³ed as: possibility of death, possibility of injury, inappropriate therapy or false diagnosis, equipment damage and no signi³cant risks. �e criterion of maintenance is associated with the level and frequency of maintenance required according to the manufacturer’s speci³cations or to the experience of the CE sector, its maximum value being attributed to a high need for maintenance, and the minimum, to a low need routine. Equipment with an EM greater than or equal to 12 must be inventoried and, as a priority, monitored by the CE sector. �e values of each factor are presented in Charts 2, 3 and 4.

2.3. MEDICAL-HOSPITAL CARE IN THE FRAMEWORK OF THE BRAZILIAN NAVY

Comprised by the healthcare, medical expert and oper-ating medicine subsystems, the Navy Health System (NHS) brings together human, material, ³nancial, technological and information resources to provide health activities in the BN (BRASIL, 2012).

�e healthcare subsystem is responsible for providing Medical-Hospital Assistance (MHA) according to three axes: prevention and health promotion; primary care; and specialized care.

The prevention and health promotion axis includes health programs and healthcare campaigns. �ese have a low cost and, in general, do not employ any technology. Primary care is the ³rst level of care; provision of basic

Chart 1. Main activities of the lifecycle phases of medical-hospital equipment and systems.

Incorporation UtilizationDiscontinuation/

renovation

Survey of requirements and technical specificationsEvaluation of solutions available in the marketAcquisition

Recycling training and equipment

trainingMaintenance

planningManagement

of maintenance contracts

Generation of technical

reportsDisposal

Communication of lessons

learned

Chart 2. Equipment function factor score.

Category Function description Score

Therapeutic

Life support 10

Surgical and intensive care

9

Physical therapy and treatment

8

Diagnostic

Surgical or intensive monitoring

7

Physiological monitors/imaging diagnostics

6

Analytical

Analytical laboratory 5

Laboratory accessories 4

Computational systems and associated

equipment3

OthersOther related

equipment2

Chart 3. Risk factor score.

Description of the use risk Score

Possibility of death of the patient 5

Possibility of injury to user or patient 4

Inappropriate therapy or false diagnosis

3

Damage to equipment 2

There are no significant risks 1

Chart 4. Need for maintenance factor score.

Need for maintenance Score

Extensive: routine calibration or part replacement

5

Above average 4

Medium: Performance verification and safety testing

3

Below average 2

Minimum: visual inspection 1

Source: Medeiros (2015).



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health services, essentially outpatient care, with the aim of reducing the �ow of patient to hospitals. Subdivided into medium and high complexity, the specialized care axis is the second level of healthcare, characterized by specialized treatment and hospitalization, with diagnostic and thera-peutic support activities and use of advanced technology. Also in relation to specialized care, the medium complexity type requires specialized professionals and employs tech-nological resources for diagnostic support and treatment. �e high complexity type di�ers by comprehending the care in reference hospitals, using highly advanced technology, at a high cost, and with quali³ed and constantly updated human resources (BRASIL, 2012).

Aside from the preventive and curative nature, the axes are distinct because of the use of health technology (levels of com-plexity), specialized personnel and associated cost. �e main characteristics of each axis are summarized in Chart 5.

Functionally, the NHS structure comprises: a Sectoral Governing Body (SGB), a specialized Governing Agency (SGA), Subsystem Coordinating Bodies and Technical Implementation Bodies (TIB).

Subordinated to the General Board of Marine Personnel (GBMP), the Navy Health Board (NHB) is organized into six departments: Planning, Technical Management, Administration, Logistics, Information Technology and Health Auditing (BRASIL, 2016c).

Subordinated to MHB, the Navy Medical Care Center (NMCC) is organized into five departments: Health, Production, Administration, Intendance and Ambulatory Assistance. In addition to the aforementioned depart-ments, NMCC also contains a Planning and Control Advisory Body and a Process Management in its struc-ture (BRASIL, 2016b).

2.3.1 Assignments of the Navy Health System Bodies

�e responsibilities of the NHB include: planning the technical visits and inspections to be carried out in the mil-itary organizations (MO) providing health care; planning technical and professional quali³cation of health personnel; elaborating the technical regulations regarding equipment and personnel that operate with ionizing radiation; super-vising, through inspections, records and registers, activities related to X-rays and ionizing substances; indoctrinating the collection, interpretation and actions resulting from the analysis of statistical data and health indicators at the naval level; acquiring permanent material for the NHS; analyzing the requests for acquisition of permanent health material from Military Hospital Organizations (MHO) (BRASIL, 2016c).

�e NHB is advised by the NMCC, TIB, in the plan-ning, organization, coordination and control of the activities of the healthcare subsystem to the level of specialized care of medium complexity (BRASIL, 2012).

NMCC, among other tasks, is responsible for conduct-ing studies related to the planning of actions related to the management plans and projects developed in its area; planning and controlling actions addressed to professional training, aiming at the technical and scienti³c improve-ment of its crew; supervising the collection, carrying out the analysis and issuing periodic opinions on the evolu-tion of statistical data and health indicators, related to the activities carried out in its sphere and in that of subordi-nated MOs, in order to advise the decision-making pro-cess (BRASIL, 2016b).

�e NMCC has an Engineering division, subordinated to the Administration Department, which, among other

Chart 5. Axes of the healthcare subsystem.

AxisHealth promotion

and preventionPrimary care Specialized care

DescriptionHealth Programs and

Assistance Campaigns.First level of outpatient

medical care.Second level of health care.

CharacteristicsLow cost and no use of

technologies.Low complexity, simple exams.

Medium and high complexity, high cost, specialized and constantly updated

professionals, technological resources to support diagnosis and treatment.



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activities, is responsible for: technical advice to the various sectors of the NMCC and subordinated MOs, regarding engineering initiatives and other property maintenance ser-vices; preparing the projects that meet the needs of actions requested by the various sectors of the NMCC and support-ing the subordinated MOs in the elaboration of projects, when requested; overseeing the progress of the schedule of civil projects and infrastructure under construction at the NMCC and subordinated MOs, when requested; super-vising, maintaining and conserving the NMCC building facilities with respect to its physical structure, electrical, hydraulic and sewage installations, air conditioning, paint-ings and ³nishes in general, and supporting the subordi-nated MOs in the maintenance of their building structures (BRASIL, 2016a).

Although NMCC has an engineering department in its organization, it is aimed at civil projects, and it is not possible to identify an arm specializing in the mainte-nance of MHS.

Despite the existence of statistical analysis, the per-formance of such an activity is strongly correlated to the selection and quality of the data to be collected. If the data is not well selected or collected, the analysis may be minor or irrelevant.

Directly subordinated to the NMCC, in relation to dental care, the Odontoclínica da Central Marinha (OCM) is the TIB of the axis of medium complexity specialized care.

3. THE ADHERENCE OF CLINICAL ENGINEERING WITH THE

BRAZILIAN NAVY

Despite its relevance, the theme of CE is still little di�used and little explored in the BN. It should be noted that success in any project, program or initiative requires the engagement of all parties involved, and CE is not an exception.

Based on the hypothesis of the low exploration of the subject in the BN, considering the TIB of the specialized attention of medium complexity, the OCM was selected for the study. �us, some characteristics of the OCM are high-lighted below.

3.1. ODONTOCLÍNICA CENTRAL DA MARINHA

�e OCM’s mission is to contribute to the e�ectiveness of the NHS in assisting the specialized dental care industry, in addition to participating in health promotion and preven-tion programs, research development and further training courses (BRASIL, 2015b).

It has 67 o¿ces, distributed in 10 specialized clinics: oral and maxillofacial surgery and traumatology; dental; temporo-mandibular dysfunction; endodontics; stomatology and oral pathology; implant dentistry; integrated dentistry; geriatric dentistry; orthodontics; periodontics and dental prostheses; in addition to the preventive dentistry, prompt care and semi-ology services (BRASIL, 2015b).

Compatible with the diversi³ed portfolio of specialized services o�ered by the OCM, state-of-the-art equipment is present in its dental park, among others: X-ray machines; Cone Beam dental scanner; clinical optical microscope; laser equipment; ultrasonic devices; and the Ceramic Reconstruction system, which performs indirect restorations on pure ceram-ics with speed and quality (BRASIL, 2015b).

The installed capacity of the OCM also includes: an orthodontic laboratory, a dental laboratory, X-ray rooms for the Dental Radiology and Imaging Service, the Nursing and Sterilization Service and a room equipped for the Patient Stabilization Service (PSS) (BRASIL, 2015b).

Faced with so many specialized services and equip-ment with several cutting-edge technologies, the struc-ture of the OCM is expected to contemplate at least one sector with di�erent skills and knowledge able to main-tain the maximum availability of the MHS, possibly an engineering division.

In the search for a specialized cell, in an analysis of the organization chart of the OCM, it was not possible to identify a CE sector. In addition, the TIB’s current military sta� do not have professionals from the Navy Engineer Corps.

Considering the size of the OCM and the amount of MHS, even though there are detailed rules and proce-dures, it can be stated that there is a gap between what is recommended by the good practices of CE and the e�ec-tive maintenance of MHS. �e selection and collection of records (or indicators) can be hampered by the absence of a team with maturity regarding the use of the equipment.



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�at is, the diagnosis is facilitated when there is a presence throughout the lifecycle.

Advancing in the structure of the NHS, it is veri³ed that the military personnel of NMCC, NHB’s advisory body in the planning, organization, coordination and control of the activities of the subsystem to the level of specialized care of medium complexity do not have o¿cers of the Marine Engineer Corps.

As detailed throughout the previous sections, the basic feature of CE is multidisciplinarity — it is not limited to the engineering personnel. However, it is not desirable to imple-ment the recommended concepts without the presence of a clinical engineer.

4. CONCLUSION

Despite the increasing evolution of the CE area and the relevance of the subject, its practices are still not very wide-spread in the BN.

Among several possible aspects to be addressed in the search for better patient care, this study presented the actions present in the CE capable of competing to balance and/or improve critical factors of healthcare and technology, proce-dures and maintenance routines for MHSs of the BN.

�e creation of regulations and standards for the safe operation of MHSs requires continuous evolution, as part of a dynamic process, with feedback from the maturity of use and maintenance (phase of the MHS’s lifecycle).

�e lessons learned during the MHS’s lifecycle signi³-cantly contribute to new speci³cations aligned with the real needs of medical teams. �erefore, they in�uence the evo-lution of products and pressure the market to improve and create new equipment.

Although the outsourcing of services is a commonly adopted possibility, it does not exclude the need for a quali-³ed team to follow maintenance routines and to identify and/or evaluate the performance of MHSs in use.

Recognition of standards, reliability assessment, failure rate veri³cation for the de³nition of the life stage of the

equipment and the identi³cation of the beginning of the aging process allow the revision and adjustment of the maintenance policy, enabling the maintenance of equipment availability at the highest level during the lifecycle. For activities such as monitoring, evaluation and determination of the appro-priate moment for disposal or replacement, it is desirable to have a CE sector.

�e knowledge of the material’s behavior and the level of obsolescence managed by the CE sector, translated by main-tenance indicators, in a time of scarcity of resources, serves as a relevant tool to support the decision to prioritize invest-ments and, consequently, to improve patient care. From the reduction of subjectivity, resources can be targeted based on quantitative criteria.

Generally, the maintenance of the MHSs is delegated to or grouped in a maintenance or engineering department, sharing and consuming resources without the proper special-ization. In addition, having a maintenance team that repairs one equipment is not enough, which signals a disadvantage in outsourcing the services without the monitoring of an inter-nal sector. It is necessary to know the level of importance of the equipment for the medical services, the dependence and the impacts that downtime can cause.

In addition, based on the paradigms of reliability-cen-tric maintenance (RCM), generic maintenance programs apply to equipment with the same operational context and with the same functions and performance standards. �us, the heterogeneous environment of specialized medium/high complexity units requires a model that increases operational availability and safety with cost reduction.

Given its potential, CE can contribute with an operation with greater availability and greater safety and, consequently, better care (service delivery) to the patient.

As future research, to follow the present study, the devel-opment of a proposal to implement a lifecycle management system for the OCM equipment is suggested. Another sug-gestion is an evaluation of the reduction in maintenance costs and the increase in the availability of MHSs with the incor-poration of a minimum structure of CE in the management of the BN’s MHS park.



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REFERENCES


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HIGH HYDROSTATIC PRESSURE APPLIED IN THE PROCESS OF

STERILIZING BIOLOGIC DRESSINGS MADE OF HUMAN AMNIOTIC MEMBRANES

Alta pressão hidrostática aplicada no processo de esterilização de curativo biológico constituído por membrana amniótica humana

Shana Priscila Coutinho Barroso1, Rachel Antonioli Santos2, Jerson Lima da Silva3, Marcelo Leal Gregório4

1. First Lieutenant (RM2-S). PhD in Biological Chemistry from the Universidade Federal do Rio de Janeiro. Military Researcher at the Instituto de Pesquisas Biomédicas/Hospital Naval Marcílio Dias – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

2. First Lieutenant (RM2-S). PhD in Neuroscience from the Universidade Federal Fluminense. Military Researcher at the Instituto de Pesquisas Biomédicas/Hospital Naval Marcílio Dias – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

3. PhD in Biophysics from the Universidade Federal do Rio de Janeiro. Full-time Professor at the Universidade Federal do Rio de Janeiro – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

4. Frigate Captain. Specialist in Coloproctology from the Hospital Naval Marcílio Dias. Specialist in Health Management from the Universidade Federal do Rio de Janeiro. Military head of the Instituto de Pesquisas Biomédicas do Hospital Naval Marcílio Dias – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

Abstract: �e biological and mechanical properties of a human amniotic membrane (HAM) enable for its use as a biologi-cal dressing to heal wounds, since it minimizes opportunistic infections, reduces pain and in�ammation of damaged tissue, and assists in the healing process. All conditions are ensured to be sterile during the processing of HAM. However, as the National Agency for Sanitary Surveillance recommends, addi-tional sterilization using physical methods is necessary when dealing with biomaterials in regenerative medicine. �is work evaluated the use of high hydrostatic pressure (HHP) as a com-plementary technique to HAM sterilization. HHP was able to decontaminate the HAM exposed to environmental microorga-nisms and Escherichia coli, but was unable to reduce the contami-nation from Staphylococcus aureus. Our results suggest that HHP is a promising, e¿cient and low-cost possibility to complement HAM sterilization.Keywords: Hydrostatic Pressure. Inactivation. Biologic Dressings. Amnion. Bacterial Load.

Resumo: As propriedades biológicas e mecânicas da membrana amniótica humana (MAH) a tornam interessante para utilização como curativo biológico em feridas de difícil resolução, uma vez que minimiza as infecções oportunistas, reduz a dor e a in�amação do tecido lesado e auxilia o processo de cicatrização. Durante o proces-samento da MAH, são asseguradas todas as condições de esterilidade do tecido. No entanto, conforme resolução da Agência Nacional de Vigilância Sanitária (ANVISA), é indicado que seja realizada este-rilização complementar por métodos físicos nos biomateriais para enxertia. Neste trabalho, avaliamos a utilização de alta pressão hidros-tática (APH) como técnica complementar de esterilização da MAH. A APH foi capaz de descontaminar a MAH exposta a microrganis-mos presentes no ar ambiente e a MAH exposta a Escherichia coli, mas não de reduzir a contaminação da MAH pelo Staphylococcus aureus. Nossos resultados sugerem que a APH é uma alternativa promissora, e³ciente e de baixo custo para esterilização complementar da MAH.Palavras-chave: Pressão Hidrostática. Inativação. Curativos Biológicos. Âmnio. Carga Bacteriana.

Shana Priscila Coutinho Barroso, Rachel Antonioli Santos, Jerson Lima da Silva, Marcelo Leal Gregório


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1. INTRODUCTION

Human skin substitutes are one of the main challenges of regenerative medicine. �e human amniotic membrane (HAM) is the innermost layer of the placenta and its biological and mechanical properties (such as the presence of growth factors, collagen types I-VII, elastin, laminin and ³bronectin) in addi-tion to its lack of immunogenicity make it especially useful for clinical use. Furthermore, when the HAM is used as a bio-logic dressing, it minimizes opportunistic infections, reduces pain and in�ammation of the damaged tissue, and helps the tissue healing process (TALMI et al., 1991; DUA; AZUARA-BLANCO, 1999; SOLOMON et al., 2001; RIAU et al., 2010).

Due to the lack of speci³c regulations, we followed the recommendation from the National Agency for Sanitary Surveillance (Agência Nacional de Vigilância Sanitária–ANVISA) and used the Resolution of the Board of Directors (RBD) No. 55 from December 11, 2015, which deals with good practices in human tissues for therapeutic use, and the recommendations of the RBD No. 220 from December 27, 2006, for the processing of the material (ANVISA, 2006, 2015).

Despite its advantages, the use of HAM has been dis-carded for years because of the risk of infection it causes for women who perform normal deliveries, but who were not serologically tested during pregnancy. However, the standard-ization of the use of grafting tissues in Brazil (regulated by Laws 9,434 / 1997 and 10,211 / 2001) and greater strictness with regard to sterility during handling, now allow for the possibility of a pathogen-free dressing and, therefore, with-out risk to the patient.

However, according to the ANVISA resolution (2006), it is suggested that complementary sterilization using phys-ical Methods be performed on biomaterials used for graft-ing. Radio-sterilization — a technique that requires expen-sive equipment, controlled use, and highly trained sta� — is commonly used in radiation doses ranging from 15 to 25 KGy (GUPTA et al., 2013; ISLAM et al., 2016). �erefore, there is a great deal of interest in the study of e¿cient and inex-pensive alternative physical methods that can be applied as a tool for the sterilization of biomaterials.

In the last few years, several studies have demonstrated the e¿ciency of the use of high hydrostatic pressure (HHP) for the elimination of pathogenic microorganisms, especially in the food industry (LOPES et al., 2010; ZHOU et al., 2010).

Hydrostatic pressure is de³ned as the pressure exerted by the weight of a static �uid column (liquid or gas), and depends on the �uid density, the �uid column depth and the local accel-eration of gravity. It is a physical parameter capable of pro-moting numerous morphological and physiological changes in organisms. More speci³cally, hydrostatic pressure induces the reduction of cell volume and, consequently, changes in the cytoskeleton, the cell wall/membrane and other cellular components (PALHANO et al., 2004a; 2004b)

In addition to the results observed in food pressuriza-tion, several studies have demonstrated the e�ectiveness of HHP in reducing infectivity and inactivating enveloped and non-enveloped viruses, bacteria and fungi in di�erent bio-logical materials ( JURKIEWICZ et al., 1995; CALCI et al., 2005; KINGSLEY; CHEN, 2009; DUMARD et al., 2013). Promising results are seen with the sterilization of biologi-cal materials, orthopedic prosthesis, blood bags and vaccine development (AERTSEN et al., 2009; BARROSO et al., 2015). �us, this study aims to evaluate the use of HHP as a complementary method for HAM sterilization.

2. RESEARCH METHODOLOGY

2.1. DECLARATION OF ETHICSThis research project was approved by the Research

Ethics Board of the Marcílio Dias Naval Hospital (Hospital Naval Marcílio Dias — CEP-HNMD), under the protocol number of the Ethics Assessment Presentation Certi³cate (Certi�cado de Apresentação para Apreciação Ética — CAAE) 34621214.1.0000.5256.

2.2. INCLUSION CRITERIA OF THE DONORS

After ³lling out the informed consent form for cesarean section surgery — women between the ages of 18 and 35 years old, who had a pregnancy with no complications and a negative serology for hepatitis B (HBsAg and total anti-HBc), hepati-tis C (Anti-HCV), human immunode³ciency virus I and II (anti-HIV 1 and 2), chagas disease (anti-Trypanosoma cruzi), syphilis (treponemal or nontreponemal test), human T-cell lymphotropic virus I and II (Anti-HTLV I and II), toxo-plasmosis (immunoglobulin G -IgG - and immunoglobulin



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M - IgM - anti-toxoplasma) and cytomegalovirus (IgG and IgM anti-CMV) - had the placenta collected. �e same serolog-ical tests were performed again in the donors after six months.

Laboratory tests were carried out in the clinical analysis sector of the Marcílio Dias Naval Hospital (Hospital Naval Marcílio Dias — HNMD).

2.3. PLACENTA / HUMAN AMNIOTIC MEMBRANE INCLUSION

CRITERIA FOR THE STUDY�e placentas were collected at the obstetric surgical cen-

ter of the HNMD. Following the guidelines of the RBD No. 220 of ANVISA (2006), microbiological investigations of fragments and tissue washes were carried out at three dif-ferent moments during the isolation procedure and the prepa-ration of the HAM for use as a biologic dressing: 1. At the time of HAM isolation;2. After the use of an antimicrobial solution;3. Prior to the preparation of the ³nal package for clin-

ical use.

Microbiological examinations investigated the presence of aerobic and anaerobic bacteria and fungus. Tissues contami-nated by bacteria and/or fungi were discarded, as were those with meconium impregnation. �e exams were performed at the HNMD Clinical Analysis Laboratory.

2.4. PREPARATION OF THE HUMAN AMNIOTIC MEMBRANE AT THE INSTITUTE

OF BIOMEDICAL RESEARCH Under sterile conditions, the placenta was washed in phos-

phate-bu�ered saline (PBS; pH 7.4) (Sigma-Aldrich) several times to remove cell fragments, blood and blood clot. �en, the amniotic membrane was manually separated from the chorion. �e HAM was incubated at 4°C for 24 hours in a sterile surgi-cal PBS containing 10,000 IU of penicillin, 50 μg/mL strepto-mycin, 2.5 μg/mL amphotericin B, and 2.5 μg/mL neomycin (Sigma-Aldrich). After this, the HAM was incubated in PBS containing antibiotics at the concentration already described and 90% glycerol at 37°C for 2 hours and then washed with PBS until the glycerol was completely removed (Sigma-Aldrich). It was decellularized in a trypsin-EDTA solution (0.05%, 0.02%) in PBS (pH 7.40) for 20 min at 37°C. With the epi-thelial side facing upwards, the mechanical removal of the cells

was performed using a cell-scraper (Corning). �e HAM was washed with Dulbecco’s Modi³ed Eagle’s Medium (DMEM) and then with a sterile saline solution.

�e HAM was adhered to nitrocellulose paper (Bio-Rad) and stored in DMEM and glycerol solution (1: 1) (Sigma-Aldrich and Vetec) in deep freezers (Indrel) at -80 ° C. �e material was then packed in primary and secondary sterile plastic packaging.

�e samples were kept in freezers at -80ºC, and were identi³ed as “tissues not released for use”, until the donor’s serological testing was repeated (4 to 6 months).

2.5. THE HYDROSTATIC PRESSURE SYSTEM

�e hydrostatic pressure experiments were performed in an apparatus consisting of two main compartments: a high-pressure cell and a pressure generator. �e pressure cell constructed by ISS® Inc. (Champaign, IL) was ³rst described by Paladini and Weber (1981), and consists of a vascomax steel block. Bottle-shaped cuvettes (with a volume around 1.3 mL) were used for pressurizing the tissue sample. �e pressure cell was maintained connected to an ultra thermostat bath (Nova Ética) to main-tain temperature (25°C) during the experiments. In this work, the samples of the HAM were pressurized to 276 megapascal (MPa) for 90 minutes.

2.6. THE EVALUATION OF THE HIGH STERILIZING CAPACITY OF

HYDROSTATIC PRESSUREAfter the isolation and preparation of the HAM for use

as a biologic dressing, we evaluated the e¿ciency of the use of HHP as a complementary sterilization method for tissues main-tained under non-sterile conditions (contamination by ambient air). For this, fragments and washes of the HAM were seeded in di�erent culture media. Each bacteria culture medium was maintained under ideal temperature conditions and evaluated 24 and 48 hours after sowing. �e culture media for fungi were kept under ideal temperature conditions and evaluated daily for up to 40 days, as described by ANVISA (2004).

HAM fragments with an area of approximately 3 × 3 cm (length × width) were used. Fragments from four di�erent experimental groups were submitted to hydrostatic pressure:• Group 1 (negative control); the HAM was manipulated accord-

ing to the ANVISA RBD No. 55 (2015), which addresses good practices in human tissues for therapeutic use;



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• Group 2 (positive control); the HAM was handled under non-sterile conditions (handled outside of the biological safety booth);

• Group 3; the HAM was contaminated with Staphylococcus aureus subsp. Aureus Rosenbach (ATCC® 25923);

• Group 4; the HAM was contaminated with Escherichia coli (Migula) Castellani and Chalmers (ATCC® 25922).

�e fragments were randomly divided into an exper-imental group (submitted to HHP) and a control group (not pressurized).

The HAM fragments were pressurized at 276 MPa for 90 minutes and subsequently seeded into culture media for growth of di�erent microorganisms. �e following media were used for the microbiological analysis of the pressurized material and the experimental controls:1. Thioglycollate medium without an indicator (a medium

for growth of demanding anaerobic microorganisms);2. Brain heart infusion (BHI) broth (a medium for culti-

vation of streptococcus, pneumococcus, meningococci, enterobacteria, non-fermenters, yeasts and fungi);

3. Sabouraud agar (A medium for growth of Candida species and filamentous fungi, particularly associated with superficial infections);

4. MacConkey Agar (for Gram negative bacilli - enterobac-teria and non-fermenting bacilli);

5. Blood agar (for the growth of non-fastidious microor-ganisms); and

6. Chocolate agar (for the growth of demanding microorganisms).

3. RESULTS

3.1. AN EVALUATION OF THE EFFICIENCY OF STERILIZATION USING HIGH

HYDROSTATIC PRESSURE ON THE HUMAN AMNIOTIC MEMBRANE CONTAMINATED

BY EXPOSURE TO AMBIENT AIRTable 1 shows the e¿ciency of the pressurization in HAM

sterilization after environmental contamination: in all culture media evaluated in this group, the presence of bacteria and/or fungi was not observed. In Figure 1, blood and chocolate culture media are shown 48 hours after exposition of HM to ambient air (Figures 1A and 1B), in which the growth of microorganisms was observed; sterile HAM (Figures 1C and 1D), with absence of microorganisms; and HAM contami-nated by the environment and then decontaminated through pressurization (Figures 1E and 1F).

Table 1. Efficiency of the complementary high hydrostatic pressure sterilization of the human amniotic membrane contaminated by exposure to ambient air.

Growth Medium Positive control1 Negative control2 Hydrostatic pressure3

Reading 24 h 48 h 24 h 48 h 24 h 48 h

Blood agar + + - - - -

Chocolate agar + + - - - -

MacConkey agar + + - - - -

Sabouraud agar + + - - - -

BHI* broth + + - - - -

Tioglicolato broth + + - - - -

BHI: Brain and Heart Infusion*; 1Positive control, corresponds to the evaluation of the contamination of the human amniotic membrane from exposure to ambient air; 2Negative control, corresponds to the evaluation of the contamination of the human amniotic membrane that was proved to be sterile by previous microbiolocial tests; 3corresponds to the evaluation of the human amniotic membrane contaminated from exposure to ambient air and pressurized at 276 MPa for 90 min; MPa: Megapascal; h: hours. All of the experiments were performed in triplicates. The Sabouraud agar contamination evaluation was performed daily for 40 days; the contamination evaluation of the Brain and Heart Infusion broth was performed until the fifth day after sowing.



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Pre

ssur

ized

HA

M(2

76 M

pa

— 9

0 m

in)

A B

C D

E F

Po

siti

ve c

ont

rol

(HA

M c

ont

amin

ated

by

the

envi

ronm

ent)

Neg

ativ

e co

ntro

l(s

teri

le H

AM

)

Figure 1. Decontamination of the human amniotic membrane exposed to ambient air after pressuzation. In A and B, culture media containing fragments and washes of human amniotic membrane handled under non-sterile conditions were seeded with bacterial colonies, indicating tissue contamination. In C and D, negative controls, culture media containing human amniotic membrane fragments and washes under sterile conditions exhibit no contamination. In E and F, the absence of microorganisms in the cultures reveals the decontamination of the human amniotic membrane exposed to ambient air after pressuzation. In A, C and E, the culture medium evaluated is a blood agar. In B, D and F, it is a chocolate agar.

HAM: human amniotic membrane; MPa: Megapascal; h: hours.



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3.2. AN EVALUATION OF THE EFFICIENCY OF STERILIZATION USING HIGH

HYDROSTATIC PRESSURE ON THE HUMAN AMNIOTIC MEMBRANE CONTAMINATED WITH ESCHERICHIA COLI (ATCC® 25922)

�e HAM handled in a sterile environment was then con-taminated with Escherichia coli (E. coli), a species of bacteria that inhabits the intestinal tract of mammals. As shown in Figure 2, the HHP was able to induce the decontamination of the HAM from E. coli, since bacterial growth was not observed in the culture media 24 and 48 hours spreading plates (Figure 2).

3.3. AN EVALUATION OF THE EFFICIENCY OF STERILIZATION USING HIGH HYDROSTATIC

PRESSURE ON THE HUMAN AMNIOTIC MEMBRANE CONTAMINATED WITH

STAPHYLOCOCCUS AUREUS (ATCC® 25923)The HAM handled under sterile conditions was

then contaminated with Staphylococcus aureus (S. aureus),

a species of bacteria frequently found in the skin and in the nasal passages of healthy people. Figure 3 shows that the applied HHP was not able to decontaminate the HAM, since bacterial colonies were observed in the culture media evaluated 24 and 48 hours spreading plates (Figure 3).

4. DISCUSSION

In recent years, numerous studies have pointed to the e¿ciency of HHP use in di�erent segments of biological area, including:1. �e production of microbiologically safe pharmaceutical

preparations (RIGALDIE et al., 2003);2. �e sterilization of medical equipment, biomaterials or

natural compounds (GOLLWITZER et al., 2009);3. �e development of vaccines (SHEARER; KNIEL, 2009;

DUMARD et al., 2013);

A B C

Growth medium Positive control1 Negative control2 Hydrostatic pressure3

Reading 24 h 48 h 24 h 48 h 24 h 48 h

Blood agar + + - - - -

Chocolate agar + + - - - -

MPa: Mega Pascal; h: hours; 1Positive control, corresponds to the evaluation of the contamination of the human amniotic membrane from exposure to ambient air; 2Negative control, corresponds to the evaluation of the contamination of the human amniotic membrane that was proved to be sterile by previous microbiolocial tests; 3corresponds to the evaluation of the human amniotic membrane contaminated from exposure to ambient air and pressurized at 276 MPa for 90 min.

Figure 2. Decontamination of the human amniotic membrane exposed to Escherichia coli after pressurization. In A, positive control, the growth of Escherichia coli in the blood agar contaning fragments and washes of human amniotic membrane contaminated with the bacterium. In B and C, a blood agar and chocolate agar, respectively, illustrate the decontamination of the human amniotic membrane exposed to Escherichia coli, but pressurized to 276 MPa with the absence of microorganisms 48 hours after sowing. In D, a summary table of the Escherichia coli contamination evaluation and the human amniotic membrane decontamination after being pressurized at 276 MPa.



| 36 |

4. �e extraction of cellular components and tissue decel-lularization for grafting (GROSS et al., 2008).

�e characteristics of HHP have made the processes based on it more attractive for application in biosciences, particularly for the development of pathogen inactivation methods for food or biological materials (LEMAY, 2002; TINTCHEV et al., 2010). For the control of microorganisms, the e�ec-tiveness of HHP is in�uenced by di�erent factors during the pressurizing process, such as pressure level, temperature and time of exposure (ZHOU et al., 2010).

Bacteria are generally sensitive to hydrostatic pressure in the range of 200 to 600 MPa, depending on di�erent fac-tors, including:1. �e species (Gram-positive bacteria are more resistant

to pressure than Gram-negative bacteria, and cocci are more resistant than bacilli) (SHIGEHISA et al., 1991; PILAVTEPE-CELIK et al., 2008);

2. �e growth phase in which the microorganisms are found (cells in the stationary phase are less sensitive to HHP) (MCCLEMENTS et al., 2001);

3. �e association of the use of pressure with other physi-cal or chemical treatment (for example, ionizing radia-tion and the addition of antimicrobials) (YUSTE et al., 2001; ANANOU et al., 2010);

4. �e choice of the parameters of the process of hydro-static pressure utilization (BUZRUL et al., 2008; DONSI et al., 2010).

�e most likely form of HAM contamination during processing is exposure to ambient air. Our results demon-strated that the HHP used in this study (276 MPa) was able to decontaminate the HAM exposed to microorganisms present in the ambient air and contaminated with E. coli, but was not able to reduce the contamination of the HAM from S. aureus, a Gram-positive bacterium described with more

A B C

Growth medium Positive control1 Negative control2 Hydrostatic pressure3

Reading 24 h 48 h 24 h 48 h 24 h 48 h

Blood agar + + - - + +

Chocolate agar + + - - + +

MPa: Mega Pascal; h: hours; 1Positive control, corresponds to the evaluation of the contamination of the human amniotic membrane from exposure to ambient air; 2Negative control, corresponds to the evaluation of the contamination of the human amniotic membrane that was proved to be sterile by previous microbiolocial tests; 3corresponds to the evaluation of the human amniotic membrane contaminated from exposure to ambient air and pressurized at 276 MPa for 90 min.

Figure 3. The high hydrostatic pressure (276 MPa) does not decontaminate the human amniotic membrane exposed to Staphylococcus aureus. In A, positive control, the growth of Staphylococcus aureus in the blood agar seeded with fragments and washes of human amniotic membrane contaminated with the bacterium. In B and C, blood agar and chocolate agar, respectively, illustrate the presence of Staphylococcus aureus in the contaminated human amniotic membrane and pressurized at 276 MPa, 48 hours after sowing. In D, a summary table of the evaluation of the human amniotic membrane contaminated by Staphylococcus aureus after being pressurized at 276 MPa



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resistance to HHP. �e literature shows that the pressure range to inactivate E. coli varies according to the medium in which it is present (FONBERG-BROCZEK et al., 2005; VAN OPSTAL et al., 2005).

HHP in the range used was not able to sterilize samples contaminated with S. aureus. Yao et al., in 2015, achieved a reduction of 3 logs of bacterial load using 350 MPa for 6 min in association with the treatment with 500 ppm of nisin (YAO et al., 2015). Wanga et al., in 2010, observed a reduction of 8 logs using 300 MPa associated with 1.2 NL/L CO2 and the reduction of 2.2 logs using 300 MPa without an association (WANG et al., 2010). Fioretto et al. (2005) demonstrated the inactivation with 3 cycles of 15 min at 450 MPa. Gervilla et al., in 2000, compiled studies showing that pressures above 500MPa are more e�ective for inactivation. Since we used 276 Mpa, we need to increase the pressure range to inactivate this bacterium (GERVILLA et al., 2000).

Gram-positive spores and bacteria are on average more resistant to pressure treatment than Gram-negative bacte-ria. �e higher resistance of Gram-positive bacteria may be related to the sti�ness of the teichoic acids in the cell wall peptidoglycan layer (ARROYO et al., 1999). �erefore, the result we ³nd is consistent with the literature.

�e tests that evaluate the preservation of the macroscopic and microscopic structure of the HAM submitted to HHP are underway. According to naked-eye observations, the pressurized material exhibits no changes to the post-processing material.

�e ³rst histochemical tests do not indicate changes in the organization and composition of extracellular matrix proteins that constitute HAM, however, new experiments still need to be performed to con³rm and disseminate the results.

HAM for use as a biologic dressing comes from donor placentas that exhibited negative serology for a series of pathogens, before a cesarean delivery and six months after it. In addition, all HAM processing is performed in a sterile environment and, during the process, microbiological con-trols are performed that con³rm the sterility of the mate-rial. �us, the use of HHP as a complementary sterilization method corroborates the decontamination of the biologic dressing without the involvement of macrostructural tissue.

5. CONCLUSIONS

�e great potential and applicability of HHP as a steriliza-tion tool makes it extremely attractive for research in di�erent areas such as the food industry, the pharmaceutical industry and tissue bioengineering. In this study, we showed that HHP is a promising alternative for HAM sterilization, when used as an e¿cient biologic dressing for chronic wounds. Although more studies are needed to assess the range of pathogens that may be present in the HAM, the results presented here appear to be the ³rst record in the literature of a physical, e�ective, and low-cost complementary HAM sterilization method.

AERTSEN, A.; MEERSMAN, F.; HENDRICKX, M.E.; VOGEL, R.F.;

MICHIELS, C.W. Biotechnology under high pressure: applications and

implications. Trends Biotechnology, v. 27, p. 434-441, 2009. https://

doi.org/10.1016/j.tibtech.2009.04.001

AGÊNCIA NACIONAL DE VIGILÂNCIA SANITÁRIA (ANVISA).

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A SIMULTANEOUS ANALYSIS OF TETRAHYDROCANNABINOL AND

CARBOXY-TETRAHYDROCANNABINOL IN URINE SAMPLES

Análise simultânea de tetrahidrocanabinol e carboxi-tetrahidrocanabinol em amostras de urina

Carla Sales Maia1, Daniel Filisberto Schulz2, Cláudio Cerqueira Lopes3, Rosângela Sabbatini Capella Lopes4, André Luiz Mazzei Albert5

1. Undergraduate degree in pharmacy from the Universidade Federal do Rio de Janeiro. Master’s degree from the Universidade Federal do Rio de Janeiro. Institute of Biomedical Research, Hospital Naval Marcílio Dias – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

2. Doctorate degree from the Universidade Federal do Rio de Janeiro. In charge of bioanalysis at the Institute of Biomedical Research, Hospital Naval Marcílio Dias – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

3. Doctorate degree from the Universidade Federal do Rio de Janeiro. Associate professor at the Institute of Chemistry at the Universidade Federal do Rio de Janeiro – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

4. Doctorate degree from the Universidade Federal do Rio de Janeiro. Associate Professor IV at the Institute of Chemistry at the Universidade Federal do Rio de Janeiro – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

5. Doctorate degree from the Universidade Federal do Rio de Janeiro. Senior Researcher at FIOCRUZ – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

Abstract: Cannabis is the most commonly used drug in the world, with about 183 million users in 2014. Δ9-tetrahydrocannabinol (THC), its primary psychoactive constituent, is associated with a variety of adverse e�ects including cognitive and memory damage, which negatively interferes in the lives of users. �e pur-pose of this work was to study the e¿ciency of ion exchange resins in the simultaneous analysis of the presence of THC and its main metabolite, 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH), in urine, through several solvent systems, and to evaluate it using high performance liquid chromatography tan-dem mass spectrometry. �e best condition with the resin sho-wed a simultaneous recovery of THC and THC-COOH from 76 to 105% and from 84 to 96%, respectively, for urine concen-trations of 25 and 100 ng.mL-1. �e methodology developed sho-wed high speci³city for the research of this chemical species in urine samples.Keywords: Cannabis. Solid-phase extraction. Tandem mass spectrometry.

Resumo: A Cannabis continua sendo a droga mais utilizada no mundo, computando cerca de 183 milhões usuários em 2014. O Δ9-tetrahidrocanabinol (THC), principal substância ativa da erva, está relacionado a uma variedade de efeitos adversos, incluindo comprometimento cognitivo e da memória, interferindo negativa-mente na vida dos usuários. A proposta deste trabalho foi estudar a e³ciência de resinas de troca iônica na análise simultânea da pre-sença de THC e seu principal metabólito, 11-nor-9-carboxi-Δ9- tetrahidrocanabinol (THC-COOH), em urina, por meio de diver-sos sistemas de solvente e avaliá-lo por cromatogra³a líquida de alta e³ciência acoplada à espectrometria de massas em série. A melhor condição de trabalho com a resina apresentou uma recuperação simultânea do THC e THC-COOH de 76 a 105% e 84 a 96%, res-pectivamente, para as concentrações na urina de 25 e 100 ng.mL-1. A metodologia desenvolvida apresentou alta especi³cidade para a pesquisa das espécies químicas de interesse em amostras de urina.Palavras-chave: Cannabis. Extração em fase sólida. Espectrometria de massas em série.

Carla Sales Maia, Daniel Filisberto Schulz, Cláudio Cerqueira Lopes, Rosângela Sabbatini Capella Lopes, André Luiz Mazzei Albert


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1. INTRODUCTION

It is estimated that a quarter of the world’s population aged 15-64 used at least one type of illicit drug in 2014. �e impacts of this consumption are devastating to health. In this same year there were 207,400 drug-related deaths recorded, and illicit drug consumption is associated with an increased risk for contracting an HIV infection. Cannabis stands out as the most widely used drug in the world, with about 183 million users in 2014 alone (UNODC, 2016).

Like other drugs such as opium, cannabis has a very broad medicinal use. One of the ³rst reports of its use for medicinal purposes occurred in China about 5,000 years ago when the plant was recommended for the treatment of malaria, consti-pation, rheumatic pain and childbirth, and additionally, it was mixed with wine to act as an anesthetic in simple surgeries. In the 19th century, this herb was used in India for its anal-gesic, anticonvulsive, antispasmodic, antiemetic and hypno-tic bene³ts. However, at the beginning of the 20th century, because its potency is highly variable, it can not be stored stably, it causes unpredictable responses after being adminis-tered orally, there were more e�ective synthetic alternatives, and there were commercial pressures regarding the recreatio-nal use of Cannabis, these therapeutic treatments lost favor. In 1928, the herb was banned through the rati³cation of the Geneva Convention, with sanctions preventing its produc-tion, sale and transportation, as it was considered a harmful drug. Cannabis could still be prescribed until its ban in 1971 (ROBSON, 2001).

Cannabis sativa L. (Cannabaceae) is part of Brazilian his-tory as well. It came to Brazil in the beginning of the 1500s when the Portuguese caravels, with their sails and ropes made of hemp ³ber, reached the new land. However, the African enslaved peoples introduced the plant in the country star-ting in 1549. It was disseminated through medical use as treatments for asthma and insomnia. In the 1930s, its varied hypnotic and sedative e�ect already caused the medical pro-fession to take caution. It was also in this decade that repres-sion against marijuana began, based on the guidelines from the Geneva Convention (CARLINI, 2006).

Currently, the import, export, trade and manipulation of the plant are prohibited in Brazil. Except for legal agree-ments and in speci³c cases, the plant is prohibited because it can be transformed into narcotic and/or psychotropic

substances (BRASIL, 1998). However, there is interest from the Federal Public Prosecutor’s O¿ce (Ministério Público Federal — MPF) in collaboration with the National Agency of Sanitary Surveillance (Agência Nacional de Vigilância Sanitária — Anvisa) to expand drug research that focuses on the drug’s therapeutic properties. Actions at the national level aim to invest in the production of new drugs for the treatment of diseases such as cancer and Parkinson’s disease (LEITE, 2017). In experimental models, Cannabis exhibits a neuroprotective e�ect and has potential for the treatment of neurodegenerative diseases such as Huntington, Alzheimer’s, neuromotor diseases, multiple sclerosis and cerebrovascular accidents (BAKER et al., 2003). Additionally, success stores for its illegal use (without medical guidance) for the treat-ment of epilepsy and regressive autism must be considered (LOPES, 2014). �is evidence has motivated political par-ties and social groups to demand that legal entities permit the use of the drug for therapeutic purposes in the country (CONSULTÓRIO JURÍDICO, 2017).

People from the United States have sought for the lega-lization of cannabis for medical purposes because of the pos-sibility for it to cause analgesic e�ects, increased appetite and reduced intraocular pressure. However, Cannabis is a plant that exhibits psychoactive properties that are associated with the distortion of time, decreased sensory perception, loss of coordination, anxiety and panic attacks. Its chronic use is related to a variety of adverse e�ects, including cognitive, memory and decision-making capacity impairments, as well as increased risk of developing psychiatric disorders (HALL; DEGENHARDT, 2009; LI et al., 2012).

It should be made clear that the therapeutic e�ects for the treatment of epilepsy and other neurological disorders attributed to C. sativa are not related to the main psychoac-tive substance, Δ9-tetrahydrocannabinol (THC), but to can-nabidiol (CBD), a cannabinoid without psychoactive acti-vity (DEVINSKY et al., 2014). �erefore, e�orts are being made to obtain a formula with a high CBD content and a low THC content to treat these diseases.

Epidemiological studies show that the consumption of Cannabis is associated with a signi³cant risk of tra¿c acci-dents, and this risk increases progressively with the frequency of consumption, due to a reduction in the consumer’s capa-city to drive. In the United States, recreational drug use and access to drugs (mainly alcohol and other illicit substances)



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for therapeutic purposes are cited as causes of auto accidents (LI et al., 2012).

Governments, private institutions and other organiza-tions have implemented stringent programs to discourage drug use and to monitor abstinence cases. �e consequences of drug use range from loss of one’s job or driver’s license, ³nes and even imprisonment (MUSSHOFF and MADEA, 2007). �e active substance in Cannabis is also on the list of substances banned by the World Anti-Doping Agency (WADA), for its unquestionable harm to athletes’ health (BRENNEISEN et al., 2010).

In this respect, the detection of drug consumption is inclu-ded in forensic and toxicological areas through the monitoring of consumption in the work environment, as well as through the highlighting of safety issues in tra¿c, aviation and mat-ters involving the custody of minors. It is an important tool for health professionals in monitoring the treatment of che-mically dependent people.

�e detection of Cannabis use depends mainly on the amount and on the sensitivity of the method of analysis, but also on the preparation, means of administration, duration of use (acute or chronic), on the biological matrix chosen for consumption and on the variations of each individual’s metabolism. THC, the main substance responsible for the psychoactive e�ects of C. sativa, and its inactive acid metabolite, 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH), are excreted in urine (GROTENHERMEN, 2005). �is is the main way to detect THC and THC-COOH from drug consumption.

The Substance Abuse & Mental Health Services Administration (SAMSHA) recommends a cuto� value of 15 ng.mL-1 of THC-COOH in urine for a positive result for cannabinoid use. �e presence of THC in urine indicates the very recent use of Cannabis, which is demonstrated in controlled studies with volunteers receiving known doses of THC, and in which the substance was detected within the ³rst ³ve hours after use (MANNO et al., 2001).

Several biological means are used to detect THC and its metabolites, such as blood, urine, saliva, hair and meconium. Due to the chemical characteristics of THC, this substance is rapidly biotransformed and distributed to the tissues. Identifying it can be hampered by the low concentrations of the active substance and its metabolites in biological matri-ces (PASSAGLI, 2011).

�e extraction, concentration and elimination of impuri-ties present in complex matrices are among the most impor-tant phases of the analytical process needed to obtain reliable results. In order to do so, a careful treatment of these sam-ples should be carried out in the pre-analytical steps, without letting the presence of interfering substances compromise the analyzes. �is could generate false data, which results from coelution and ion suppression, especially in samples in which the actual concentration of the molecules of interest is already very low.

Solid-phase extraction (SPE) is a liquid-solid extraction technique based on the separation principles of classical liquid chromatography. �e sample, in liquid form, and con-taining the analyte of interest, is placed in a cartridge contai-ning a solid phase, also called a sorbent, and the substances of interest are isolated from the complex matrix (LANÇAS, 2004). �e SPE procedure is used not only for the extraction of organic traits, but also for the elimination of interfering substances (GONZÁLEZ; ARRIBAS, 2000).

Ionic exchangers are insoluble solid materials that, depending on their nature, can perform cation exchanges, anion exchanges or both (amphoteric). �e species that are removed from the solution are replaced by a stoichiometric amount that is equivalent to the ionic species of the same charge. �e excess of a positive or negative charge is com-pensated by a counter-ion of the opposite charge. �ese can be removed and replaced by others of the same charge that are present in solution, ensuring the balance of the system. �erefore, this is a stoichiometric di�usion process that depends on electronic equilibrium from the redistribution of counter-ions between the pores, liquids and the solution (HELFFERICH, 1962).

Some of the materials widely used in SPE are ion exchan-gers, which can be obtained from synthetic or natural mate-rials. �e resins produced from the polymerization of styrene are the most widely used. Exchange functional groups are inserted in them, which confer characteristics of cation, anion or amphoteric exchanges on them (HABASHI, 1993 apud RIANI, 2008). Such polymers consist of a matrix structure, which is formed by an irregular network of hydrocarbon chain macromolecules that have characteristic properties in function of their structure. �e resin matrix is hydro-phobic. Hydrophilic binders are introduced by the incor-poration of ionic groups such as -NH3

+ or -SO3-. �e resins



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are insoluble because they have several networked hydro-carbon chains with elastic properties and non-uniform mesh in order to accommodate the solvent. �e behavior of the resin is de³ned by the ionic groups incorporated in the hydrocarbon matrix. Its capacity is determined by the number of ionic groups. �e chemical nature of the groups establishes the equilibrium and the selectivity of the resin (HELFFERICH, 1962).

The use of ion exchange resins can be applied in the identi³cation of di�erent molecular groups. In association with high performance liquid chromatography (HPLC) and mass spectrometry, they are an e¿cient analytical tool for the detection of substances in complex matrices. �e aim of this work is to present the development of an analytical methodology for the simultaneous recovery of THC and its main metabolite from urine samples enriched with a known amount of the substances of interest. In the end, we aim to standardize the analysis protocol.

2. MATERIALS AND METHODS

2.1. REAGENTSCerti³ed standards of THC (1.0 mg.mL-1), THC-COOH

(100.0 μg.mL-1) and the internal standard of THC-COOH-d3 (100 μg.mL-1) were purchased from the Cerilliant Corporation (USA). Sodium hydroxide, sodium carbonate, formic acid, ammonium formate, Dowex Cl® resin 1 × 8 200-400 Mesh and ethyl acetate were obtained from SigmaAldrich (St. Louis, USA). Sodium bicarbonate, acetonitrile HPLC and hexane were purchased from J.T. Baker (USA). Methanol HPLC was purchased from J.T. Baker (Mexico), hydrochloric acid was purchased from MACRON (Mexico), and STRATA X-C® was purchased from Phenomenex USA.

2.2. STANDARDSA MIX of the THC (1.0 mg.mL-1), THC-COOH (100.0

μg.mL-1) standards, and the internal standard THC-COOH-d3 (100 μg.mL-1) were diluted successively in methanol to obtain working solutions in the concentration of 1.0 μg.mL-1.

2.3. SAMPLESFor the negative control, a set corresponding to ³ve urine

samples, a “pool”, was obtained from healthy volunteers who

declared that they were not Cannabis users. �is was con-³rmed by mass spectrometry. �e samples were prepared in triplicate and identi³ed as follows: Forti³ed white: a 50 μL MIX solution of 500 ng.mL-1 standards was added to 1 mL of negative control. �e adding in of the standards was per-formed prior to the hydrolysis step. White: 1 mL of negative control was submitted to the extraction process and it was free of standards. Positive control: 50 μL of the MIX solu-tion of the standards were added to 1 mL of negative control after the extraction procedure with the resin.

2.4. HYDROLYSIS100 μl of 10 N NaOH solution were used in the urine

samples. �ey were heated at 60°C for 20 minutes (HUQ et al., 2005) to promote the hydrolysis of THC and THC-COOH conjugated to glucuronic acid, which is the product of metabolism of phase II biotransformation in animals and in humans.

2.5. EQUIPMENT AND ACCESSORIES�e samples were analyzed using an Agilent Technologies

1200 Series high performance liquid chromatograph (Waldbronn, Germany) coupled with an API tandem mass spectrometer, and an AB Sciex (Singapore), operating on the multiple reaction monitoring (MRM) mode using an elec-trospray ionization source. �e monitored transitions for the investigated substances are presented in Table 1.

High performance liquid chromatography coupled with tandem mass spectrometry (HPLC – MS/MS): this method contemplated two periods in a single chromato-graphic run, using the negative and positive polarities in the MRM mode. �e source parameters are described in Table 2. In period 1, from 0 to 3.5 minutes, the EM/EM detector operated in the negative mode for THC-COOH analysis. In the second period, from 3.5 to 10 minutes, the mass spectrometer operated in the positive mode in order to determine THC.

Chromatographic separation was performed with a Kinetex® C18 chromatography column, 50 × 2.1 mm, 2.6 μm, Phenomenex (USA). �e mobile phase used was 0.1% (v / v) aqueous solution of formic acid, designated as phase A, and phase B was a 0.1% (v / v) solution of formic acid in aceto-nitrile, with a �ow of 450 μL.min-1, an injection volume of 3 μL and a column oven temperature of 20°C.



| 44 |

Table 1. Transitions monitored in multiple reaction monitoring mode with their respective collision energies and applied potential at the entrance of the collision cell.

THC: Δ9-tetrahydrocannabinol; THC-COOH: 11-nor-9-carboxy-Δ9-tetrahydrocannabinol; CEP: cell entrance potencial; CE: collision energy; *more intense product ions used to quantify substances.

NameMolecular

weight

TransitionCEP CEMass

Q1 (Da)Mass Q3

(Da)

THC-COOH 1

344343.0[M-H]-

245.0

-32.4

-34

THC-COOH 2

299.0* -15.07

THC-COOH 3

191.0 -26.50

THC 1

315315.0

[M+H]+

193.0*

19.11

31

THC 2 123.0 37

THC 3 93.0 33

Table 2. High performance liquid chromatography interface parameters coupled with tandem mass spectrometry for the final method in the multiple reaction monitoring mode.

THC: Δ9-tetrahydrocannabinol; THC-COOH:11-nor-9-carboxy-Δ9-tetrahydrocannabinol; CUR: gas curtain; TEM: turbo temperature; GS1: nebulizer gas 1; GS2: auxiliary gas 2; CAD: collisionally activated dissociation; EI: electrospray ionization; EP: entrance potencial; DP: declustering potencial; CEP: cell entrance potencial; CXP: collision cell exit potential.

ParametersTHC

(positive mode)THC-COOH

(negative mode)

CUR (psi) 12 12

TEM (ºC) 700 700

GS1 (psi) 50 50

GS2 (psi) 40 40

CAD (psi) 3 3

EI (V) 5500 -4500

EP (V) 10 -7.5

DP (V) 61 -55

CEP (V) 19,11 -32.14

CXP (V) 3 -4

2.6 SOLID PHASE EXTRACTION�e work began by comparing the recovery e¿ciency of

THC and THC-COOH simultaneously in urine samples with two ion exchange resins: (1) Strata X-C®, with 60 mg of cation exchange sorbent; (2) Dowex Cl® resin 1 × 8 200-400 Mesh, with anion exchange in the quantities of 60 mg and 200 g (Sigma Aldrich, Brazil), which were packaged in the labo-ratory (experiments 1 and 2).

�e parameter selected to evaluate the performance of the resins was the ratio between the areas of the forti³ed blank and the positive control.

In experiment 1, the commercial cartridges STRATA X-C® 60 mg, conditioned with 1 mL of methanol and 0.1 M solution of HCl, were used. 1 mL of 50% solution of formic acid was added to the cooled sample at room temperature and this solution (pH 3 to 4) was added to the cartridge. �e resin was washed with 1 mL of 0.1 M HCl solution and 1 mL of 0.1 M HCl / acetonitrile solution (80:20, v/v). �e cartridge was dried with a vacuum for 15 minutes and eluted with 1 mL of 4% acetic acid solution in acetonitrile (v/v) 2 times.

In Experiment 2, cartridges packaged in the labora-tory with 60 mg of Dowex Cl® anion exchange resin were conditioned with 1 mL of methanol and then with 1 mL of 25 mM ammonium formate solution. 3 mL of 0.1 M bicarbonate bu�er solution was added to the sample, and then slowly added to the cartridge. �e resin was washed with 1 mL of 25 mM ammonium formate solution and 1 mL of ammonium formate / ACN solution (80:20, v / v). �e cartridge was then dried with vacuum for 15 minutes and eluted with 1 mL of 4% acetic acid solution in aceto-nitrile (v / v) 2 times. �e results were compared and the subsequent experiments were conducted with the Dowex Cl® 1 × 8 200-400 Mesh anion exchange resin, altering the steps of the extraction process in order to obtain the best simultaneous recovery condition of the analytes from the resin. Experiment 3 was carried out in the same way as experiment 2, di�ering only in the amount of sorbent in the cartridge, which was altered from 60 to 200 mg. For the remaining experiments, 60 mg of Dowex Cl® resin was standardized. Experiment 4 consisted of the same pro-cedures as Experiment 2 with the addition of the volume of 1 mL hexane / ethyl acetate (1: 1 v / v) to the elution step. In experiment 5, the conditions of experiment 4 were



| 45 |

maintained, but water (pH 4 to 5) was used in the condi-tioning and washing steps. In Experiment 6, the procedures of Experiment 4 were maintained, replacing only 1 mL of hexane / ethyl acetate (1: 1 v / v) per 1 mL hexane / iso-propanol (1: 1 v / v). Finally, in experiment 7, the same procedures of the analytical test 4 were repeated, replacing the 4% (v / v) solution of acetic acid with the 5% (v / v) solution of formic acid in acetonitrile, and maintaining the following step with 1 mL hexane/ethyl acetate (1: 1 v / v).

For the comparative evaluation of the variances between the experiments, the F statistical test was applied.

3. RESULTS

�e Dowex Cl® 1 × 8 200-400 Mesh® anion exchange resin showed recoveries of 64.42 and 76.45% for THC-COOH and THC, respectively. In the cation exchange resin, the objective of recovering the two analytes simultaneously, with a very low THC yield (8.21%), was not achieved. After the statistical test F, no di�erences were observed between the experiments using 200 and 60 mg of Dowex Cl resin (expe-riments 2 and 3), therefore, the remaining tests were carried out using 60 mg of anionic resin.

After elution with 4% (v/v) acetic acid in acetonitrile (experiment 2), the addition of 1 mL ethyl acetate hexane (1: 1 v / v) (experiment 4) improved the recovery of both substances and, therefore, this step was included in the pro-cess. 5% formic acid was substituted for acetic acid and better yields were achieved with the analytical conditions of expe-riment 7, obtaining 87.57 and 76.02% of THC-COOH and THC, respectively, in the concentration of 25 ng.mL-1 of the standards of the chemical species surveyed in the sample. Figure 1 shows the recoveries obtained in each resin opti-mization experiment.

A recovery analysis was performed on urine samples from healthy volunteers who did not use the drug. �ey were forti³ed with known amounts of THC standards and their metabolite before the hydrolysis step and after the recovery procedure and after the clean up with the resin.

�e results were obtained from the ratio of the areas of six forti³ed urine negative control samples at three concentration levels, prior to the hydrolysis procedure. �ey were compared to the areas of three forti³ed samples after the preparation

Figure 1. Comparative profile among experiments in recovery of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol and Δ9-tetrahydrocannabinol.

9080706050403020100

exper

imen

t 1

exper

imen

t 2

exper

imen

t 3

exper

imen

t 4

exper

imen

t 5

exper

imen

t 6

exper

imen

t 7

11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH)Δ9-tetrahydrocannabinol (THC)

%

Analytes

Recovery (%)

25 ng.mL-1

50 ng.mL-1

100 ng.mL-1

11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH)

83.68 88.86 96.15

Δ9-tetrahydrocannabinol (THC)

76.02 79.52 104.85

Table 3. Results of recovery trials for 11-nor-9-carboxy-Δ9-tetrahydrocannabinol and Δ9-tetrahydrocannabinol in three different concentration ranges.

of the SPE, and they followed the initial concentrations in order to make the comparison, according to the Equation 1:

Recovery (%) = Sample area forti³ed before × 100 (1) Sample forti³ed after

�e technical literature recommends acceptable reco-very values between 70 and 120% for this concentration range (RIBANI et al., 2004). �erefore, the results obtai-ned for this parameter are within the criteria of consent practiced. �e results for the recovery assays are presen-ted in Table 3.



| 46 |

of THC, leading to low recoveries of the analyte in this matrix (Figure 2). In the case of THC-COOH, the elec-tron density of the carboxyl stabilizes the positive charge of the protonated oxygen in the acid medium, making it di¿cult to open the ring.

�e application of resins to separate ions comes from the di�erence in charge constants for various ionic species and the ease with which these species can be separated from the liquid phase (TOMPKINS, 1950). In this work, with the anion exchange resin, good results were obtained in the preliminary tests. �is is due to the chemical characteristics of the target analytes. �e presence of phenol and carboxyl in the structure of THC and THC-COOH, respectively, give these molecules characteristics of weak acids. �e pH adjustment to obtain THC and THC-COOH in the ioni-zed form allowed the phenoxylate and carboxylate ions to be retained in the strongly anionic phase of the resin, a qua-ternary ammonium salt. �ere is probably also considerable interaction between the polyvinylbenzene polymer with the side alkyl chain and the non-aromatic rings present in the structures of the substances studied. �e interfering spe-cies were eliminated because they lacked a¿nity with the ion exchange surface or in the washing steps. �e elution step permitted the recovery of the analytes in the absence of interfering substances (Figure 3).

�e Dowex® anion exchange resin, which has a high exchange capacity of more than 1.2 meq.mL-1 (manufac-turer’s speci³cations), was run with the amounts of 60 and 200 mg at the same time. �us, due to environmental and cost-related issues related to waste management, we opted for the standardization of 60 mg of anion exchange resin to continue the optimization.

4. DISCUSSION

SPE cartridges with the C18 and C8 polymers were used in the clean up step (ROBAND; KLETTE; SIBUM, 2009; WEINMANN et al., 2000), but SPE cartridges using can-nabinoid speci³c sorbents were used to improve the yield of the analyses (ABRAHAM et al., 2007).

In order to choose the best recovery process and clean up of the sample, it was necessary to consider the behavior of the molecules studied in solution under the di�erent pH conditions and, based on these parameters, to propose solvent systems that serve the purpose of the simultaneous recovery of the investigated substances in the urine.

�e structures of THC and THC-COOH do not pre-sent site exchangers in the molecules that can interact with the cationic exchangers. However, there is a considerable recovery of THC-COOH, which probably occurs due to the hydrophobic interactions between the polyvinylbenzene resin and the metabolite. Analyses performed by Huq et al. (2005) under the same conditions with urine samples for THC-COOH analysis show similar results to those presented in this study. �ese authors support the hypothesis that the structural nature of the metabolite, with two non-aromatic rings and a side alkyl chain, are capable of strongly interacting my means of dispersive π-π bonds with the divinylbenzene polymer in the resin matrix. Furthermore, they speculate that the interaction between the electronically de³cient benzene ring attached to the sulfonic group with the THC-COOH aromatic ring is possible.

�e THC recovery from the cation exchanger was very small. �e hydrophobic interactions described by Huq et al. (2005) possibly occur in a similar way with THC, except for the H exchange of phenol, which exhibits low acidity (pKa = 9.34). However, the assumption for the low yield is supported by the analytical conditions of the SPE system, in the conditioning and washing steps with 0.1 N HCl solutions. �is favors the acidic hydrolysis

Figure 2. Acid degradation of Δ9-tetrahydrocannabinol (THC).

HC1

THC CBD

OH OH OH

HOO O

H Figure 3. This figure illustrates the interaction of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) and Δ9-tetrahydrocannabinol (THC) with the anion exchange resin.

R3

NR1 R2

Cl–

*

+R2

NR1 R2

Cl–+

R2

NR2 R2

Cl–

–3Cl–

+ R2R3

NR1 R2+

NR1 R2+

R2

NR2 R2+

*o–

o

o

–o

o–

o

o– o–

o

oo–

o



| 47 |

In the extreme condition of the extract from the alkaline hydrolysis of 1 mL of urine with a 10 N NaOH solution, the molecules of interest in the hydrolyzed sample were like anions at pH 10. However, the urine extract was preventa-tively diluted in a carbonate bu�er solution, in order not to damage the resin matrix.

According to Collins (1997), the OH- ion has a lower a¿nity for the resin than the Cl- ion, therefore, even partial replacement of the Cl- by the OH- in the conditioning step inserts the hydroxyl counterions in the resin, activating it and thereby increasing the a¿nity for the analytes in question. �e best results were obtained when the 25 mM ammonium formate solution, instead of water, was used in the conditio-ning and washing steps.

Sout, Horn and Klette, in 2001, using 3 mL of urine and anion exchange resin (CerexPolicrom THC, 50 mg of sorbent, 3 mL of capacity) obtained a recovery rate of 95% THC-COOH. However, the method described does not contemplate the simultaneous investigation of THC and THC-COOH.

�e acceptance criteria for a positive sample of Cannabis in urine, according to SAMSHA, is a value equal to or greater than 50 ng.mL-1 for screening tests, and above 15 ng.mL-1 in con³rmatory tests for THC-COOH using mass spectrometry detection. �e cut-o� value of 15 ng.mL-1 avoids false positive results from passive inhalation of smoke (BRENNEISEN et al., 2010).

Due to its lipophilic characteristics during abstinence, THC is released into the bloodstream of the body’s storage compartments, especially the adipose tissue, and is excreted in the urine as a metabolite (THC-COOH), intermittently, for weeks (GOODWIN et al., 2008).

In users whose self-report corresponds to sporadic con-sumption, the last positive result after abstinence occurs on an average of 4.2 days (3.3 to 4.5) and for frequent users, 16.6 days (4 to 28). In urine, THC-COOH is not monoto-nously eliminated and its concentration may �uctuate bet-ween positive and negative results for a few days. A range of 6.2 days has been reported between 28 and 34 days after the last consumption (SMITH -KIELLANDT; SKUTERUD; BRLAND 1999). �us, serial monitoring is necessary to evaluate drug excretion, which increases the detection win-dow. �e detection of THC in the urine is indicative of very recent consumption of the drug, which is detectable for up to 5 hours in the urine after the consumption of the herb (MANO et al., 2001).

Due to the pharmacokinetic characteristics of THC and its main biotransformation product, the use of a method to obtain the two chemical species simultaneously is important for early and late detection of drug consumption from a sin-gle analytical assay.

5. CONCLUSIONS

�e method developed for the detection of THC and THC-COOH in urine, (which demonstrates Cannabis sativa consumption), using the Dowex Cl® ion exchange resin in the preparation of the samples, presented excellent results and showed potential for its immediate use in controlling the use of this drug. Furthermore, it showed the possibility of being adapted and applied for the detection of this consumption in other research matrices of cannabinoids, like plasma, breast milk and meconium.

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| 49 |

SPECIAL MATERIALS

DEVELOPMENT OF NATIONAL BASE BLEED PROPELLANT GRAIN APPLIED

FOR EXTENDED RANGE AMMUNITIONDesenvolvimento de grão propelente base bleed nacional

para aplicação em munição de alcance estendido

Maurício Ferrapontoff Lemos1, Priscila Simões Teixeira Amaral Paula2, Arnaldo Miceli3, Laurílio José da Silva Júnior4, Edson da Silva Souza5

1. Researcher and Master in Metallurgic and Material Engineering, Universidade Federal do Rio Grande do Sul. Group of Material Technology, Instituto de Pesquisas da Marinha – Rio de Janeiro, RJ – Brazil. E-mails: [email protected]; [email protected]

2. CT (EN) Doctor in Technology of Chemical and Biochemical Processes, Universidade Federal do Rio de Janeiro. Group of Material Technology, Instituto de Pesquisas da Marinha – Rio de Janeiro, RJ – Brazil. E-mails: [email protected]; [email protected]

3. Senior technologist, bachelor of Chemistry, Universidade Federal do Rio de Janeiro. Group of Material Technology, Instituto de Pesquisas da Marinha – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

4. Mechanical engineer, Universidade Estadual do Rio de Janeiro and graduate in Computing, Pontifícia Universidade Católica do Rio de Janeiro. Coordinator of Engineering and Development in Empresa Gerencial de Projetos Navais, Fábrica de Munições – Rio de Janeiro, RJ – Brazil. E-mails: [email protected]; [email protected]

5. CMG (FN-RM), Technical Assessor and Master in Mechanical and Weaponry Engineering, Instituto Militar de Engenharia da Empresa Gerencial de Projetos Navais, Fábrica de Munições – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

Resumo: O objetivo do presente trabalho foi desenvolver e caracte-rizar um grão propelente gerador de gás para sistemas base bleed de munições de calibre 114,3 mm (4,5”) com alcance estendido, para canhão 4.5” Mk8. O efeito base bleed é um dos métodos para diminuir o arrasto total em projéteis supersônicos. Envolve o aumento da pres-são na base por meio da geração de produtos de combustão na região de recirculação na traseira do projétil. Partindo da necessidade de nacionalização desse sistema, pesquisadores do Instituto de Pesquisas da Marinha (IPqM) se pronti³caram a pesquisar e desenvolver um grão propelente para esse ³m. Foram analisadas suas propriedades tér-micas, químicas e balísticas. O teste de desempenho em campo na Linha II de tiro do Campo de Provas da Marambaia (CPrM) mos-trou aumento de 19% no alcance da munição, passando de 21,4 km, de uma munição convencional, para 25,5 km em munição contendo o grão propelente base bleed desenvolvido neste trabalho.Palavras-chave: Materiais Energéticos. Grão Propelente Sólido. Munição de Alcance Estendido.

Abstract: �is study aimed to develop and characterize a gas-generating propellant grain for base-bleed systems of 114.3 mm (4.5”) caliber extended range ammunition for a 4.5” Mk8 cannon. �e base-bleed e�ect is one of the known methods to decrease the total drag of supersonic projectiles. It increases the basis pressure by generating gaseous products in the recirculation region of the projectile’s rear area. Motivated by the need to nationalize this sys-tem, researchers of the Brazilian Navy Research Institute (IPqM) endeavored to research and develop a propellant grain for this pur-pose. Its thermal, chemical, and ballistic properties were studied. �e ³eld performance test at Line II of the shooting range in the Marambaia (CPrM) proof ³eld resulted in an increase of 19% in the ammunition range; conventional ammunition reached up to 21.4 km, whereas extended range projectiles with the base bleed propellant grain developed in this work reached up to 25.5 km.Keywords: Energetic Materials. Solid Propellant Grain. Extended Range Ammunition.

Maurício Ferrapontoff Lemos, Priscila Simões Teixeira Amaral Paula, Arnaldo Miceli, Laurílio José da Silva Júnior, Edson da Silva Souza


| 50 |

1. INTRODUCTION

Propellant grains, explosives, and pyrotechnics are strategic energetic material from the point of view of defense due to their use in gun systems, such as missiles and rockets, as well as in satellite launch vehicles. Brazil is a country of continen-tal dimensions, with 8,000 km of coast extension that must be protected, since its natural richness are totally observed. �erefore, investment should be aimed towards research in national energetic materials to ensure the country’s bellicose independence and to extend the capacity of defense and dis-suasion power of the Brazilian Armed Forces.

Energetic materials are different compositions, made of fuel and oxidant material that tend to react for a short time after ignition, releasing a great amount of energy and gaseous products generated by the reaction. Gas-generating propellant grains are energetic materials devel-oped for extensive use in civil and military sectors, which are known by their dual use. These propellant grains are used to generate pressure in hydraulic and control devices, to inflate airbags in cars, to inflate boats, life-savers, and emergency devices, as well as in landing sys-tems. In the military sector, one important application of these propellant grains is in extended range ammunition (AEst), in systems known as base-bleed.

�e trajectory and reach of ammunitions when launched are in�uenced by aerodynamic performance parameters. �e drag that ammunition projectiles su�er after a gunshot can be divided into three components: form or pressure drag, friction drag, and basis drag (COSTA; BARBOZA, 2000). �e latter comes from air vortices and turbulences that produce a low-pressure region in the projectile’s basis and are especially considerable in supersonic conditions (Belaidouni; Živković; Samardžić, 2016). In this regimen, the basis drag is responsible for at least half of the total drag in high-caliber ammunitions (ZHANG; TIAN; ZHANG, 2017; Belaidouni; Živković; Samardžić, 2016). �erefore, the base-bleed e�ect consists in a method to decrease the basis drag through increase of pressure in the projectile’s rear area with the injection of hot gases at low velocity in the recircula-tion region (ZHANG; TIAN; ZHANG, 2017; BOURNOT; DANIEL; CAYZAC, 2006; KLÖHN; RASSINFOSSE, 1982). Such e�ect may increase the ammunition reach in up to 30%, in comparison with conventional ones, since

it reduces the basis drag in up to 70% (ZHANG; TIAN; ZHANG, 2017). Figure 1 represents a projectile with the coupled system.

Unlike rocket motors, the propellant grain fuel chamber settling for base-bleed does not have a nozzle, but it has a ³xed diameter hole. Its functioning may not generate an additional thrust and, thus, the propellant grain burns in low-pressure regimens and may be tested at room pressure (ZHANG; TIAN; ZHANG, 2017). However, propellant grains for base-bleed systems are very similar to solid fuels used in rocket motors. Both are composites produced from a polyurethane matrix, using hydroxyl terminated polybu-tadiene (HTPB) like polyol, reinforced with particles of an oxidizing salt — usually ammonium perchlorate (AP) (ZHANG; TIAN; ZHANG, 2017; DE LA FUENTE, 2009; KOMAROV, 1999). Some other formulations of energetic materials may also be used, such as pyrotechnics (FETHEROLF et al., 1988).

Base-bleed propellant grains are strategic to a country due to their use for increasing ammunition reach (XUE; YU, 2016). A meeting held in Athens, Greece, in 1988, gathered several groups of countries dedicated to drag reduction technology through base bleed. It is noteworthy that countries such as the United States (FETHEROLF et al., 1988), Germany (BÖRNGEN; HAHN, 1988), Switzerland (GUNNERS; ANDERSSON; NILSSON, 1988), China (PAN; ZHU; WANG, 1988), Israel (GANY, 1988), France (GAUCHOUX; COUPEZ; LECOUSTRE, 1988), Norway (HAUGEN; MELBY; OPPEGÅRD, 1988), Yugoslavia ( JARAMAZ; INJAC, 1988) and, more recently, Egypt (YOUSSEF et. al., 2017), among many others, already possess AEst ammunition technology, as well as the apparatus for well-sophisticated experimental tests for analysis of the AEst ammunition performance.

Chamber

Propellant grainRe-ignitor

Figure 1. Scheme of a projectile with the base-bleed system.



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In Brazil, base-bleed propellant grains are not manufac-tured locally. A ³rst study initiative on the subject was published in 2000. It is a ³nal course project from stu-dents of the Instituto Militar de Engenharia (IME) for the development of base-bleed systems for 155-mm howit-zer grenades (COSTA; BARBOZA, 2000). Nevertheless, there is no record that this nationalization has developed for use in shot tests in proof ³elds.

Therefore, its development is of Brazil’s great inter-est, specifically for the Navy. In addition, the national-ization of this system may endow our Defense Industrial Basis (BID) with potential for production and export of AEst ammunition.

Motivated by the need of Fábrica de Munições Almirante Jurandyr da Costa Müller de Campos (FAJCMC) to develop this system, the Brazilian Navy Research Institute (IPqM) endeavored to develop a 114.3 mm (4.5”) AEst caliber base-bleed ammunition gas-generating propellant grain for a 4.5” Mk8 cannon. The study followed all the nec-essary stages for research and development of a product. Not only the material characterization and development of several formulations in laboratory were made, but also a performance test was carried out in the field of Restinga da Marambaia.

2. OBJECTIVE

�e main objective of this paper was to develop a gas-gen-erating propellant grain that provides a base-bleed e�ect, spe-ci³cally for 114.3 mm (or 4.5”) ammunition.

3. RESEARCH METHODOLOGY AND EXPERIMENTAL PART

3.1. PRODUCTION OF PROPELLANT GRAINS�e following raw materials were used for manufactur-

ing propellant grains:• AP (NH4ClO4) 99% purity: oxidizing substance used in

di�erent grain sizes;• aluminum: powder, reducing agent;• HTPB, (C12H18)n(OH)2, n=50: pre-polymer in the form

of a viscous �uid that, in the reaction with a diisocyanate, will constitute the plastic matrix where the solid particles will be distributed;

• dioctyl phthalate (DOP), C24H38O4: plasticizer used for adapting viscosity and allowing a good incorporation of solids in the plastic matrix;

• toluene diisocyanate (TDI), C9H6N2O2: substance that, in the reaction with HTPB, results in polyurethane plas-tic matrix.

�e raw materials were mixed for 6 hours in a planetary vertical mixer DAY mixer, with three sigma rods, maintained at a 60ºC and vacuum.

�e mold (Figure 2A) was projected by the IPqM and manufactured at FAJCMC. �e material used in the inhi-bition as the propellant grain coating is polyvinyl chloride (PVC). After casting the dough in the mold, it was taken for curing in an oven cabinet at 60ºC for 24 hours before extraction. After complete cure, the propellant grain was cut for the manufacture of three base-bleed grains. Figure 2B

A B

Figure 2. Propellant grain manufactured at Instituto de Pesquisas da Marinha after extraction of the mold and the three grains after cure, ready for use.



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shows the propellant grains, with inhibitions over the extrem-ities, ready for use in ammunition.

3.2. MATERIAL CHARACTERIZATIONSamples were extracted from the propellant grain for

thermal analysis, kinetics of thermal decomposition, deter-mination of calori³c potential, and for analysis by Fourier transformed infrared spectroscopy (FT-IR).

�ermal analyses of thermogravimetry (TG) and its deri-vate (DTG) and di�erential thermal analysis (DTA) was per-formed with the �ermogravimetric Simultaneous Analyzer Model SDT Q600, of TA Instruments brand, in heating ratios of 5, 10 and 20ºC/min in nitrogen atmosphere, with a �ow of 100 mL/min. �e mass of samples was around 1.5 mg and the temperature ranged from 25 to 600ºC, with the use of a platinum crucible. In order to obtain the activation energy of decomposition through di�erential scanning calorimeter (DSC), a Shimadzu �ermal Analysis TA-50 system was used in N2 atmosphere at a �ow of 30 mL/min. �e equations foreseen in the kinetic model of Flynn, Wall and Osawa are described in the ASTM 698-05 standard. For the kinetics heating rates of 5; 7.5; 10; 12.5 and 15°C/min were applied, and a partially sealed platinum crucible containing a sample with mass around 1 mg (MOTHÉ; AZEVEDO, 2009) was used. For measure-ments of calori³c potential in triplicate, 1.1±0.15 g samples were extracted. �e equipment used was PARR 1281 Isoperibol Calorimeter in oxygen or nitrogen atmosphere.

�e FT-IR infrared spectroscopy analysis was performed with the PerkinElmer SPECTRUM ONE spectrophotom-eter (basic conditions: 4,000–400 cm-1 region, 4 cm-1 reso-lution, gain 1 and 20 screenings). �e propellant grain was analyzed in the form of KBr pellet, as received and after treatment with solvents.

In order to obtain information regarding the surfaces of the studied propellant grain samples, they were covered with platinum and observed in a screening electronic microscope (SEM), HITACHI Tabletop Microscope TM 3000.

3.3. STATIC FIRING TEST�is test preliminarily assesses the performance of propellant

grains manufactured for the base-bleed unit. We assessed the burning time and �ame aspect (length and width) in this test. �e thrust generated by the gas-generating propellant grain is considered null. �ese parameters are important to determine

if a propellant grain formulation may or may not meet the requirements corresponding to those from a base-bleed unit.

�e testing workbench was projected and manufactured by FAJCMC and is a bipartite metallic recipient. �e infe-rior half is ³xed in the test workbench and the superior half is removable to allow propellant grain positioning for testing. An igniting pyrotechnics device was screwed to the basis of the metallic recipient to simulate the unit’s real conditions, whose assembly scheme is shown in Figure 1.

�e empty space in the central axis of the propellant grain is ³lled with black gunpowder and an initiator is placed in the superior part, in contact with the gunpowder for its igni-tion. �e burning test begins at distance and is recorded with a high-speed camera.

3.4. BALLISTIC TESTINGS IN PROOF FIELD�e shot tests of the conventional ammunition and AEst

ammunition were conducted using a 4.5” MK8 cannon at Line II of the Marambaia Proof Field (CPrM), in Rio de Janeiro (Figure 3), angled at 45º. �e ammunition used was high explosives (HE), acclimatized at 15ºC. To visualize the projectile shortly after being expelled from the steel tube, an Olympus iSPEED 3 high-speed chamber was used with a rate of 2,000 charts/s. �e speed was determined through a WEIBEL Scienti³c A/S radar (SL-525P type, 8742 series, 81 batch). �e reach was determined by observers using com-pass-goniometers in 3 points of observation, located at 22, 24 and 26 km from the shot point.

Figure 3. 4.5” mk8 cannon inclined at 45º for shot test in the Field Tests of Marambaia.



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4. RESULTS AND DISCUSSION

4.1. MATERIAL CHARACTERIZATIONIn Figure 4A, we observe the TG, DTG and DTA curves

from the propellant grain. �e TG curve showed three decom-position stages: between 200 and 300ºC; between 300 and 390ºC (main decomposition); and between 430 and 480ºC. There was almost no residue after 600ºC temperature. �e DTG curve also showed three stages of decomposition and we could observe an endothermal event in the DTA curve at 240ºC and three exothermal events at 280, 330 and 370ºC – the two latter ones were superposed.

�e DSC results of the propellant grain showed an endo-thermal event associated with change of the AP crystalline phase around 250°C (Figure 4B). �e peaks posterior to the main one may be associated with a reaction of sub-products from the main decomposition, which occur due to the closed system applied in the analysis, and are not associated with loss of mass. With the use of the equations foreseen in the kinetic model by Flynn, Wall and Ozawa (described in the ASTM E 698-05 standard), we were able to obtain a value of 122.58 kj/mol for the propellant grain’s thermal decom-position activation energy. Peaks regarding the maximal tem-peratures of the exothermal reaction used in the equations are highlighted in “ZOOM A” chart of Figure 4B. A kinetic analysis of similar sample, performed in a thermogravimetric analysis equipment that followed Friedman’s model and was

previously published (PAULA; MOTHÉ; MOTHÉ, 2015), showed three stages of decomposition in the ranges of 171–253°C, 253–393°C and 393–496°C, as well as dependence of activation energy (E) and of the pre-exponential factor log-arithm (log A) with the conversion degree (mass loss frac-tion), where there was an increase in the values of (E) from 146 to 183 kJ/mol and in the values of (log A) from 10.1 to 12s-1 for the conversion range from 0.2 to 0.8.

The calorific potential measure in inert environment (“explosion” heat) performed in the isoperibol calorimeter resulted in the value of 1,155.69±1.97 cal/g, whereas the potential in oxidant atmosphere (combustion het) was of 2,832.60±34.94 cal/g.

�e spectrum obtained through the FT-IR of the pro-pellant grain as manufactured is illustrated in Figure 5. �e main absorptions seen are attributed to the AP: around 3,130 cm-1 due to stretching of the NH4

+ groups; 1,400 cm-1, deformation region of the NH4

+group; and around 1,087; 1,111; 1,144 and 636 cm-1 regarding the stretching of ClO4

-

groups (NYQUIST; KAGEL, 1971).Figure 6 shows the FT-IR spectrum of the propellant

grain after AP removal. �e main absorptions observed were (SILVERSTEIN; BASSLER; MORRIL, 1981): 3,300 cm-1 due to stretching of groups NH and/or OH of humidity; 2,850 and 2.900 cm-1, CH stretching in CH2; 1,730 cm-1, stretching of the C=O group; 1,640 cm-1, stretch-ing of ole³ns C=C; 1.236 cm-1; 1,236 cm-1, stretching of C-O; 966 cm-1, angular deformation of groups CH trans;

Temperature (°C)

0.6

0.4

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Propellant grain DSC 114.3 mm (5°C/min.)

Propellant grain DSC 114.3 mm (7.5°C/min.)


Propellant grain DSC 114.3 mm (12.5°C/min.)


ZOOM A

20

15

10

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-5

120

100

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mas

s (%

)

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eriv

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Temperature (°C)0 50 100 150 200 250 300 350 400 450 500

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C [

mW

/mg

]

Thermogravimetry

Derivate thermogravimetry

Di�erential thermal analysis

A B

Figure 4. (A) Curves of thermal analyzes of thermogravimetry, derivate thermogravimetry and differential thermal analysis of the base-bleed propellant grain; (B) Curves obtained through differential exploratory calorimetry of the propellant grain using different heating rates (5; 7.5; 10; 12.5 and 15°C/min). Peaks of the decomposition process (exothermal reaction) are highlighted in the ZOOM A chart.



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910 cm-1, ω angular deformation of CH vinyl groups; and 718 cm-1, regarding ω angular deformation of CH cis. Such absorptions are characteristics of the polyurethane based on HTPB (MATTOS et al., 2002).

�e photomicrography performed in SEM(Figure 7) shows the AP particles adhered well to the propellant grain’s polyurethane matrix. �e presence of di�erent AP particle sizes used in the propellant grain’s formulation and the rel-atively good dispersion of the particles in the polyurethane matrix are also noteworthy.

4,0

00

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T%75

65

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T%

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B

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Figure 5. Spectrum in the Fourier transformed infrared of the base-bleed propellant grain analyzed as received (without treatment). On the right, a comparison of spectrum A of the propellant grain with ammonium perchlorate (spectrum B).

4,0

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T%70686664626058565452504846

T%

A

B

Figure 6. Spectrum in the Fourier transformed infrared of the base-bleed propellant grain after treatment with solvents. On the right, a comparison of propellant grain spectrum (A) with polyurethane (spectrum B).

Recently published studies show that the basic ingredi-ents for producing these gas-generating propellant grains are, indeed, HTPB and AP (YU et al., 2014; ZHANG; TIAN; ZHANG, 2017).

4.2. STATIC FIRING TESTSBurning velocity tests published in recent literature demon-

strate that experiments carried out at pressure may be applied in the study of propellant grains for use in base-bleed system (ZHANG; TIAN; ZHANG, 2017).



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Figure 8 shows the workbench during one of the per-formed tests. The propellant grain burn was continuous and presented uniform aspect, without unexpected sparks.

Prop D 2015/07/30 11:40 N 500umx200D7.5

Figure 7. Micrography of propellant grain with a 200x magnification.

Figure 8. Propellant grain test in a fixed-point workbench.

�e two propellant grains that underwent preliminary tests of performance presented burning times of 23 and 21 sec-onds. Considering that the recommended time interval of burning for the same test of the base-bleed unit is 20 to 24 seconds, the tests were considered satisfactory, given that they were performed at the same conditions.

Other more sophisticated tests simulating real conditions of ammunition shot may be applied, including the stage of fast depressurization that occurs when the projectile is ejected from the cannon (YU et al., 2014). Such experiments will be considered for future analyses of the product obtained in this paper and for comparison with the present tests.

4.3. TESTS IN PROOF FIELD�e shot tests performed at CPrM performed very well.

�e conventional ammunition obtained a 21.4 km reach. The AEst ammunition, using the base-bleed propellant grain developed by the IPqM, reached a 25.5 km distance. �is result represents a 19% increment in the ammunition reach. Figure 9A illustrates a moment right after the shot, showing the projectile with lit propellant grain. Figure 9B, which is a still image of a video made with a high-speed cam-era, shows the AEst ammunition right after the shot, with the base-bleed propellant grain active at the projectile’s basis.

Figure 10A represents the basis drag e�ect and Figure 10B shows what happens when a gas-generating propellant grain is lit. In the conventional ammunition, which has been illus-trated in the ³rst image the free air�ow coursing in the pro-jectile at supersonic speed expands at the projectile’s end basis corner. �en, the turbulent air�ow su�ers a separation, where part of the free �ow follows ahead and su�ers recom-pression and realignment after the passage of the metallic body; the other part forms a region of primary recirculation with inverse air�ow that characterizes an air rarefaction zone (XUE; YU, 2016). With the ejection of a continuous �ow of gaseous mass from the projectile’s basis, longitudinal and symmetric to the capsule’s axis (as illustrated in Figure 10B), there is a division and an intensity decrease of this primary recirculation region (XUE; YU, 2016; Belaidouni; Živković; Samardžić, 2016). In addition, a small annular air recircula-tion, opposed to the primary recirculation region, is formed. Such phenomena consequently decrease the basis drag.

Due to the obtained reach, we characterized that the ammunition tested in this study presented this aerodynamic



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A B

Figure 9. (A) Test of ammunition shot of extended reach in 4.5” mk8 cannon; (B) projectile after shot showing the base-bleed propellant grain developed at Instituto de Pesquisas da Marinha after its inflammation.

Figure 10. Schemes representing the projectile’s basis without (A) and with (B) ejection of the basis mass. Source: adapted from Xue and Yu (2016) and Belaidouni, Živković and Samardžić (2016)

Expansion wavesA

B

External flowSupersonic Recompression

A

Basis

RealignmentB

Primary recirculation

Expansion waves

External flowSupersonic

Recompression

Basis

Realignment

Primary recirculation

Gas ejection

Recirculation



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behavior and good �ight stability. �e in�ammation (igni-tion) did not change the value of the initial velocity nor the pressure value. �erefore, the propellant grain worked only as a gas generator and not as additional propulsion system; thus, it changed the ammunition reach only through the decrease of the basis drag.

5. CONCLUSIONS

�e present study described the experimental methodol-ogies and the results obtained in the development of a pro-pellant grain for base-bleed systems, applied in AEst ammu-nitions. Physical and chemical characterizations of the mate-rial were performed. �e ³eld tests showed that the purpose of increasing the reach of 114.3 mm (4.5”) ammunition was achieved. �e reach changed from 21.4 km, with conventional

ammunition, to 25.5 km, with AEst ammunition, using the propellant grain developed in this study.

�rough the study carried out by the IPqM, the Brazilian Navy becomes a national pioneer in the development of this propellant grain for ammunition of such caliber. �erefore, this development contributed a lot to the national autonomy and to the BID support for producing this kind of ammunition.

6. ACKNOWLEDGEMENTS

�e authors would like to thank the Chemistry Division (AQI) from Instituto de Aeronáutica e Espaço (IAE) and to the Departamento de Ciência e Tecnologia Aeroespacial (DCTA) of the Brazilian Armed Forces for their valuable mechanical and FT-IR analyses performed.

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SOLUTION OF THE MULTI-LAYER AIR DEFENSE WEAPON ALLOCATION

PROBLEM WITH THE MONTE CARLO SCANNING METHOD

Solução do problema de alocação de armas de defesa aérea em multicamadas com o método Monte Carlo Scanning

Alexandre David Caldeira1, Wilson José Vieira2

1. Nuclear engineer, DSc, researcher at Instituto de Estudos Avançados – São José dos Campos, SP – Brazil. E-mail: [email protected]

2. Nuclear engineer, PhD, researcher at Instituto de Estudos Avançados – São José dos Campos, SP – Brazil. E-mail: [email protected]

Abstract: In this paper, the Monte Carlo Scanning Method (MCS) is applied to the minimization of a continuous function and to the maximization of a discrete function, characteristic of the problem of allocation of multilayer air defense weapons. �e MCS Method uses random sampling and considers that the speed of modern computers makes it possible to ³nd optimal solutions by scanning the domain and inspecting the function image. �e qua-lity of the results achieved indicates that this method can provide solutions that are compatible with those produced by other opti-mization methods. Due to its simplicity and robustness, it is belie-ved that the MCS Method can be implemented as a computer simulation tool for military decision support systems.Keywords: Monte Carlo Simulation. Weapon Allocation Problem. Decision Support Systems.

Resumo: Neste trabalho, o Método Monte Carlo Scanning (MCS) é aplicado à minimização de uma função contínua e à maximização de uma função discreta, característica do problema de alocação de armas de defesa aérea em multicamadas. O Método MCS utiliza amostragem randômica e considera que a velocidade dos computa-dores modernos possibilita encontrar soluções ótimas por meio da varredura do domínio e da inspeção da imagem da função. A qua-lidade dos resultados alcançados indica que esse método pode for-necer soluções compatíveis com as produzidas por outros métodos de otimização. Devido à sua simplicidade e robustez, acredita-se que o Método MCS possa ser implementado como uma ferramenta de simulação computacional para sistemas de apoio à decisão militar. Palavras-chave: Simulação Monte Carlo. Problema de Alocação de Armas. Sistemas de Apoio à Decisão.

1. INTRODUCTION

Computer tools that support military decision for the allocation of air defense weapons in multilayers are related with the need to protect critical infrastructures of military installations, aerospace system etc. This situa-tion means, for instance, the protection of port installa-tions, rail and bus complexes and industries of defense products. Therefore, the development of military deci-sion support systems to help with the planning of the

defense against air strikes gains increasing importance in the Ministry of Defense.

In the 1970s, the development of deterministic methods was emphasized. One of the main reasons for that was the availability of fast algorithms to solve linear equations. Considering the slow speed of computer processing at the time, the applications of the Monte Carlo Methods were very limited. Nowadays, with the increasing speed in processing, this method has become a powerful computer simulation tool to solve complex problems.

Alexandre David Caldeira, Wilson José Vieira


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�e allocation of weapons is a problem related with the proper placement of defense weapons against a striking force to minimize the damage on its own assets, and to maximize the damage to the strike force. Usually, it can be categori-zed as a static or dynamic problem, when considering the temporal intention in the combat. It can also have a single goal, or multiple goals, which consider di�erent optimiza-tion criteria and are more consistent with real combat situa-tions (LI et al., 2017).

Generally, the weapon allocation problem is considered to be temporal, polynomial, and non-deterministic. �is implies that the time for solution increases exponentially with the size of the problem. �erefore, there are no exact methods to solve the general problem. �e study of the problem began in the 1950s, and, since then, has been incorporating new methods, such as the Genetic Algorithm, the Complete Linear Programming, the Simulated Annealing (SA), Neural Networks, Tabu Search, Particle Swarm and other hybrid algorithms (LI et al., 2017; MADNI; ANDRECUT, 2009). However, in the absence of exact algorithms, no estimation can be made about the quality of the solutions produced by these heuristics.

Considering the great complexity that the problem may present, it is necessary to solve simple cases that may evolve to much more complex models. In this paper we present a new approach called the Monte Carlo Scanning (MCS), developed in the Geointelligence Division (EGI) at the Institute for Advanced Studies. To verify the methodology, a literature problem ( JAISWAL, 1997) that uses the SA Method is solved.

�e MCS Method considers the high speed of cur-rent computers to rapidly build samples that meet the restrictions imposed, and to ³nd optimal solutions only by sweeping the domain and inspecting the image of the objective function. Besides, it is possible to visualize both, the domain itself and the image, verifying if there was enough sampling in the domain and analyzing the beha-vior of the solutions.

�e MCS Method does not have the mathematical and computational sophistication of the aforementioned methods, which compose the state of the art. However, because of the facility to implement and the absence of computatio-nal complexity, this approach allows obtaining fast solu-tions for highly complex problems, with many restrictions.

Another advantage is the facility to adjust it with the increa-sing complexity of the simulation. It is important to notice that, for most realistic simulations (BOORD; HOFFMAN, 2016), only basic Monte Carlo techniques are used for the simulation of subsystem parameters and components used in the project.

Section 2 describes the MCS Method. In Section 2.1, the method is used to ³nd the global minimum value of a continuous function (BOHACHEVSKY et al., 1986), which presents several local minimums and one global minimum. In Section 3, the method is used to solve one problem of maximization of a discrete function, which is characteristic of the allocation of defense weapons or air strike ( JAISWAL, 1997). Finally, Section 4 presents the ³nal comments and recommendations for further studies.

2. THE MONTE CARLO SCANNING METHOD

In simpler optimization problems, the use of deter-ministic methods is more appropriate. However, with the increasing complexity of the problem, it is necessary to use more sophisticated computational methods, which are, the-refore, more di¿cult to implement, like, for instance, the SA Method.

Like the SA Method, the MCS Method uses a random sample in the domain of the independent variables, and calculates the value of the objective function. However, the MCS Method, unlike the SA Method, does not have a convergence algorithm in the search of the maximum and the minimum of the objective function. �erefore, the sam-ples are generated independently in the entire domain, verifying if they meet the restrictions. �is implies that the implementation of the parallel process is facilitated. �e selection process of the MCS Method is much sim-pler when compared to the SA Method, which searches for a new sample in the vicinities of the previous sample. �ere are random samples of many dots in the domain to uplift the structure, the shape and the maximum and minimum existing dots, therefore covering the image of the objective function.

The sweeping process uses the basic Monte Carlo principle, also known as the Inverse Transform Technique



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(KROESE et al., 2011), in which the random samples dis-tributed uniformly in the interval [0, 1] are used to obtain values in accordance with practically any distribution law. Considering a random variable ξ uniformly distributed in the domain [0, 1], the sampling of any function distribu-tion of probabilities f (x), de³ned in the interval [-∞, ∞], can be conducted as:

F(x) = (x)dx = x = F–1( )–

x (1)

Considering that:

(x) 0; (x)dx = 1–

(2)

�is simple formulation can be extended to more dimen-sions when the variables are independent. If the variables are dependent, it is necessary to use co-variances and other forms of sampling correction.

Another famous way of interpreting the basic principle of Monte Carlo is called the Rejection Technique (KROESE et al., 2011). �is technique is an alternative path for the sampling of a distribution function when it is not necessary or convenient to calculate the inverse of F(x).

�e MCS Method consists simply on the application of the Rejection Technique to the problem of weapon allocation. �is means that the samples are generated in each dimension of the variables, however, only the samples that meet all of the restrictions will be part of the solution domain. �is procedure represents just one application of the Rejection Technique, used for the sweep in all dimensions and variables, with the objective of ³nding only valid samples. �is is the main reason to call the sample the Monte Carlo Scanning, and to distinguish it from other Monte Carlo techniques, like the SA Method, for example.

As mentioned earlier, no estimation can be made about the quality of the heuristic solutions. �e MCS Method does not allow these estimations either. However, it is possible to use only the Law of Large Numbers (KROESE et al., 2011) as the quality criterion, or the successive growth of the sam-pling size. Besides, the identi³cation of peaks in the com-plete image of the domain and the frequency of occurrence of these peaks are facilitated when the MCS Method is used. Considering the speed of computers and the greater capacity to generate samples, this veri³cation can be considered as

greater robustness of the MCS Method in relation to other methods. Besides, these same criteria are usually used as stop parameters by other methods.

Considering its methodological simplicity, some of the interesting features the MCS Method are the facility in implementation and the robustness of the solution. �e main requirement of the method is a computational capacity that is compatible with the level of di¿culty of the problem. �e MCS Method can represent a change in paradigm in the solution of optimization problems, especially for highly complex problems, with many restrictions.

2.1. EXAMPLE OF APPLICATIONIn order to illustrate the application of the method and

to verify the quality of the results, the example used is the minimization of a continuous function known in the litera-ture (BOHACHEVSKY et al.,1986):

Φ(x, y) = x2 + 2y2 – 0,3cos(3πx) – 0,4cos(4πy) + 0,7 (3)

Since the variables x and y are independent, and there is no restriction for any of them, all pairs (x, y) are accepted.

�e interest is in reaching the global minimum, Φmin. = 0,0, and its coordinates xmin. = ymin. = 0,0. Figure 1 presents the visualization of the objective function Φ(x, y) with many local minimums and the global minimum in (0,0).

To reach this goal, values of x∈ [-1, 1] e y∈ [-1, 1] are used and sampled according to Equation 1. �en, the func-tion values are calculated and stored. To make sure that the

Figure 1. Objective function Φ(x, y).

4

3.5

3

2.5

2

1.5

1

0.5

1 10 0

–1 –1

0.50.5

–0.5 –0.5

0

Y X



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function domain is fully sampled, this procedure is repeated for enough times. Finally, the calculated function values are listed in ascending order. �e ³rst value in the list corres-ponds to the minimum value of the function.

Figures 2, 3, and 4 show, respectively, the domain, the image and the ascending ordered image of the objective function Φ(x, y) generated with only 500 dots using the MCS Method. �e ³rst dot in Figure 4 represents the mini-mum value of the function corresponding to the coordi-nates (0,0).

3. MAXIMIZATION OF THE PROBLEM OF

AIR DEFENSE WEAPONS

�e problem of allocation of air defense weapons con-siders the attack plan of the enemy to be known, and the objective is to allocate the defense weapons in multilayers to maximize target protection ( JAISWAL, 1997). Each layer is de³ned by one type of defense weapon. �e global objective function is the probability of survival of the set of targets. Since this problem can involve the simultaneous manage-ment of a great amount of information, the computational time for the solution polynomially increases ( JAISWAL, 1997). Therefore, for very complex problems, heuristic methods should be used.

Table 1 presents the main variables ( JAISWAL, 1997) used in the de³nition of the discrete objective function, cha-racteristic of the problem of allocation of air defense weapons.

�e probability of survival of a target s, when attacked by all weapons, of all types of attack weapons a, is expressed by ( JAISWAL, 1997):

HS = Aa=1

Dd=1[1 – { (1 – kdsa)xdsa/nsa}gsa]nsa (4)

�e objective of the defense is to maximize the expected survival value of all targets, which is expressed by the global discrete objective function:

Figure 2. Function domain Φ(x, y). generated with the Monte Carlo Scanning Method.

1

–1

–0.8

–0.6

–0.4

–0.2 0

0.2

0.4

0.6

0.8 1

0.8

0.6

0.4

0.2

0

–0.2

–0.4

x

–0.6

–0.8

–1

y

3.5

0 50 100

150

200

250

300

350

40

0

450

500

3

2.5

2

1.5

1

0.5

n

0

PH

I(x,

y)

3.5

0 50 100

150

200

250

300

350

40

0

450

500

3

2.5

2

1.5

1

0.5

n

0

Asc

end

ing

PH

I(x,

y)

Figure 3. Image of the function Φ(x, y). generated with the Monte Carlo Scanning Method.

Figure 4. Image of the function Φ(x, y). generated by the Monte Carlos Scanning Method, in ascending order.



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Table 1. Description of the variables used.

D Types of defense weapons available.

S Number of Targets.

A Types of strike weapons.

Ra Number of strike weapons type a.

kdsa

Probability of success in the interception of a strike weapon type a, by a defense weapon d, placed to defend target type s.

gsa

Probability of a single strike weapon type a destroying target s, once it overcomes the defense layers.

nsa

Number of attack weapons type a allocated for target s (attack plan).

Vs Value or importance associated with target s.

Bd Number of defense weapons type d available.

cd Operational cost of a defense weapon type d.

Cmáx.

Maximum operational cost of the allocated weapons.

md

Number of people to operate a defense weapon type d.

Mmáx.

Maximum number of people to operate defense weapons type d.

td Area required by a defense weapon type d.

Gs Area available for the defense of target s.

xdsa

Number of defense weapons type d allocated to intercept strike weapons type a, to defend the target type s (defense plan).

FXN = Vs * HsSs=1 (5)

�e maximization process of the global discrete objective function, FXN, should meet the restrictions of:a) Availability of weapons:

xdsa Bd para d = 1, 2, ...,DSs=1

Aa=1 (6a)

b) Availability of area:

tdxdsa Gs para s = 1, 2, ...,SDd=1

Aa=1 (6b)

c) Maximum cost

cdxdsa Cmáx.Dd=1

Aa=1

Ss=1 ; e (6c)

d) Maximum available number of defense weapon operators

mdxdsa Mmáx. para d = 1, 2, ...,DSs=1

Aa=1 . (6d)

�e procedure to use the MCS Method consists of ran-domly showing defense plans as follows:

xdsa = F –1 ( , Bd) (7)

In which ξ is a random number distributed uniformly in the interval [0, 1], and F–1 is a function that provides a dis-tribution of values for xdsa. �en, according to the Rejection Technique, it is important to verify if xdsa meets the restric-tions given by Equations 6a, 6b, 6c e 6d, so that it can be considered as a valid sample. Finally, the corresponding value of FXN is calculated, given by Equation 5. �e maximum value of FXN is associated with the best defense plan found.

In this problem ( JAISWAL, 1997), whose scenario is represented schematically in Figure 5, the defense plan consi-ders 2 types of defense weapons (d1 e d2), 100 type 1 weapons

Figure 5. Example of schematic scenario of the problem of air defense weapon allocation.



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(B1=100) and 50 type 2 weapons (B2=50), which are available to protect 3 targets (S1, S2 e S3) against two types of attack weapons. �e importance values of the ³rst, second and third targets are V1=400, V2=300 and V3=200, respectively. �e known attack plan is composed of 50 type 1 weapons (R1=50) and 29 type 2 weapons (R2=29). Table 2 contains the probabilities of

defense weapon destruction, and Table 3 shows the probabi-lities of strike weapon and attack plan destruction.

For a sample of 200,000 random defense plans, the result produced by the MCS Method is compared with the results found in the literature ( JAISWAL, 1997), and those obtai-ned with the computer software of Air Defense Weapon Allocation (AADA), developed at EGI, which uses the SA Method. �e optimal defense plans, the Estimated Target Survival (SEA) and the maximum values of FXN are pre-sented in Table 4.

Using the extensive calculations with the AADA soft-ware, it was possible to see the occurrence of a minor increase in the global survival of targets when the protection of Target 3 is eliminated. However, this minor di�erence leads

Table 2. Probabilities of destruction of defense weapons.

Source: Jaiswal (1997).

Type of defense weapon (d)

Target (s)

Type of strike weapon (a)

kdsa

1 1 1 0.20

2 1 1 0.60

1 1 2 0.35

2 1 2 0.50

1 2 1 0.25

2 2 1 0.50

1 2 2 0.20

2 2 2 0.45

1 3 1 0.35

2 3 1 0.45

1 3 2 0.25

2 3 2 0.65

Table 3. Destruction probabilities and attack plan.

Source: Jaiswal (1997).

Target (s)Type of strike weapon (a)

gsa nsa

1 1 0.015 5

1 2 0.055 9

2 1 0.075 25

2 2 0.040 7

3 1 0.060 20

3 2 0.075 13

Table 4. Results for the optimal defense plans considering the attack plan is known.

*Jaiswal, 1997; **AADA: Air Defense Weapon Allocation; SEA: Estimated Target Survival; FXN: Global Discrete Objective Function; MCS: Monte Carlo Scanning.

Plan

Target 1 (V1=400) Target 2 (V2=300) Target 3 (V3=200) SEATarget

FXN(Max.)

a=1 a=2 a=1 a=2 a=1 a=2

d=1 d=2 d=1 d=2 d=1 d=2 d=1 d=2 d=1 d=2 d=1 d=2s=1 s=2 s=3

111 211 112 212 121 221 122 222 131 231 132 232

Attack* 5 9 25 7 20 1388 36 42 61

Defense* 0 0 47 0 39 14 0 5 11 16 3 15

Defense** (i) 0 5 50 0 50 36 0 9 0 0 0 0 93 59 11 63

Defense** (ii) 0 3 47 0 19 31 2 3 32 0 0 13 91 43 38 63

MCS Defense (i) 0 2 52 0 40 45 1 2 3 0 3 0 91 56 12 62

MCS Defense (ii) 5 2 36 1 3 26 4 0 34 3 17 18 88 32 50 61



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the defense plans with or without the protection of Target 3 to be found as maximum solutions. �ese conditions are represented in Table 4, showing the ³nal (i) and interme-diate (ii) results, which are the closest ones to those repor-ted by Jaiswal (1997).

�e, the application of the MCS Method was considered for the problem of allocation of strike weapons. For that, the minimization of the objective function was carried out, con-sidering a known defense plan. In this case ( JAISWAL et al., 1993), 50 strike weapons type 1 and 30 strike weapons type 2 are available. �e destruction probabilities are also showed in Tables 2 and 3.

Table 5 presents the results published in the literature ( JAISWAL et al., 1993) and those obtained by the MCS Method (MCS1 to MCS5). Using a processing with 500,000 samples of attack plans, those presenting FXN values lower or equal to 45% were chosen aiming at illustrating that there are several possible combinations of allocation of strike weapons that produce similar results for FXN. �is condition is also a result of the characteristic of heuristic methods, which have the inherent risk of producing suboptimal solutions. Table 5 shows the Estimated Target Destruction (DEA), which also helps the process of choosing the best attack plan. �is deci-sion about one or the other plan with similar FXN is up to the mission planner.

4. FINAL COMMENTS

�e greatest contribution of this study is to show that the speed of current computers allows the use of very simple Monte Carlo techniques. �e MCS Method allows the planning of allocation of defense weapons and air strike in a facilitated and intuitive manner. Besides, the problems of weapon allo-cation solved are considered big and complex enough for real situations (KARASAKAL, 2008). Still, the MCS Method was very accurate, as observed in the results presented.

Considering the simplicity, the robustness and the quality of the results reached with the MCS Method, both for mini-mizing a continuous function and for maximizing discrete functions, its use in optimization problems is very promi-sing. �e solutions found with the MCS Method for defense weapon allocation and air strike problems in multilayers are equivalent to those obtained by other computational methods found in the literature.

�e frequent use of the MCS Method allows the user to acquire the capacity and the experience required to use the software well, without the need to know other methods, which are di¿cult to implement, deeply. Besides, the users can have a broad view of the envelope of probabilities that rule the events of aircraft destruction and target vulnerability. �erefore, they can collaborate with the construction of more

Plan

Target 1 (V1=400) Target 2 (V2=300) Target 3 (V3=200) DEATarget

FXN(Min.)

a=1 a=2 a=1 a=2 a=1 a=2

d=1 d=2 d=1 d=2 d=1 d=2 d=1 d=2 d=1 d=2 d=1 d=2s=1 s=2 s=3

111 211 112 212 121 221 122 222 131 231 132 232

Defense* 0 0 39 8 42 12 0 10 13 13 6 751 64 49 45

Attack* 1 28 28 1 21 1

Attack MCS1 2 30 40 0 8 0 56 84 9 45

Attack MCS2 0 30 29 0 21 0 55 67 49 43

Attack MCS3 0 29 37 0 12 1 53 80 21 45

Attack MCS4 0 29 38 0 12 1 53 82 21 45

Attack MCS5 0 29 29 1 18 0 53 67 41 45

Table 5. Results for the optimal strike plans considering the defense plan is known.

DEA: Estimated Target Destruction; FXN: Global Discrete Objective Function; MCS: Monte Carlo Scanning. *Jaiswal et al., 1993.



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detailed scenarios, proposing improvements in the software for the solution of new problems. Finally, it is important to mention that the computer software with the MCS Method used in this study was developed in the MatLab environment (MATLAB, 2010).

6. ACKNOWLEDGMENTS

To João Camilo da Silva, of the Geointelligence Division of the Institute for Advanced Studies, for providing the map used to design the scenario shown in Figure 5.

BOHACHEVSKY, I.; JOHNSON, M.E.; STEIN, M.L. Generalized

Simulated Annealing for Function Optimization. Technometrics, v. 28,

p. 209-217, 1986.

BOORD, W.J.; HOFFMAN, J.B. Air and Missile Defense Systems

Engineering. Flórida: CRC Press, 2016.

JAISWAL, N.K. Military operations research: quantitative decision

making. International Series in Operations Research & Management

Science. New York: Springer Science+Business Media, 1997.

JAISWAL, N.K.; SHROTRI, P.K.; NAGABHUSHANA, B.S. Optimal

Weapon Mix, Deployment and Allocation Problems in Multiple

Layer Defense. American Journal of Mathematical and Management

Sciences, v. 13, n. 1-2, p. 53-82,1993.

REFERENCES

KARASAKAL, O. Air defense missile-target allocation models for a

naval task group. Computers & Operations Research, v. 35, 2008.

KROESE, D.; TAIMRE, T.; ZDRAVKO, I.B. Handbook of Monte Carlo

Methods. Nova York: Wiley Series in Probability and Statistics, 2011.

LI, Y.; KOU, Y.; LI, Z.; XU, A.; CHANG, Y. A Modified Pareto Ant Colony

Optimization Approach to Solve Biobjective Weapon-Target Assignment

Problem. International Journal of Aerospace Engineering, 2017.

MADNI, A.M.; ANDRECUT, M. EÏcient Heuristic Approaches to

the Weapon–Target Assignment Problem. Journal of Aerospace

Computing, Information, and Communication, v. 6, jun. 2009.

MATLAB. MATLAB version 7.11.0. Natick, Massachusetts: The Math

Works Inc., 2010.


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EVOLUTIONARY PROGRAMMING MODEL FOR ACTIVITY PLANNING IN MAINTENANCE WORKSHOPS

Um modelo de programação evolucionária para programação de atividades em oficinas de manutenção

Manoel Carlos Pego Saisse1, Sergio Medeiros da Nobrega2, Rafael Novaes Lago3, Lianderson Giorges Leite Rodrigues4, Leonardo Amorim do Amaral5

1. Senior technologist, PhD in Production Engineering Sciences by the Engineering Sector of Evaluation and Production, Instituto Nacional de Tecnologia – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

2. In charge of the department of Networks and Systems. Java programmer, special technical qualification in Telematics, Brazilian Navy, Centro Tecnológico do Corpo de Fuzileiros Navais – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

3. Programmer/system analyst. Specialization in Information and Communication Technology Management by the Universidade Cândido Mendes. Second Sergeant, Fusiliers Marin (SG-FN-IF), Comando do Pessoal de Fuzileiros Navais – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

4. In charge of the Telematics Sector. Bachelor’s degree in System Analysis, Universidade Estácio de Sá. First lieutenant, Reserve of 1st Navy Class (RM1-T), Centro Tecnológico do Corpo de Fuzileiros Navais – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

5. Commander. Master’s degree in Nuclear Engineering. Head of the Science, Technology and Innovation Department of Centro Tecnológico do Corpo de Fuzileiros Navais – Rio de Janeiro, RJ – Brazil. E-mail: [email protected]

Resumo: O³cinas de manutenção que realizam reparos corretivos enfrentam frequentes mudanças nas características de suas deman-das. Essa questão é ainda mais crítica quando se trata da manuten-ção de equipamentos militares, sujeitos a altos níveis de esforço e desempenho. Como consequência, os responsáveis pela atribuição dos recursos disponíveis às atividades de reparo ao longo do tempo desenvolvem um considerável repertório de conhecimentos que não conseguem ser devidamente formalizados, em razão da velocidade com que são gerados e consumidos. Neste artigo, foi proposto um modelo de programação evolucionária associado à simulação dis-creta para gerar soluções de programação de atividades em uma o³-cina de manutenção. O modelo proposto se utiliza do conhecimento tácito embutido em planos de trabalho formulados previamente por programadores de produção experientes para gerar soluções apri-moradas de programação de atividades, e foi formulado com base no caso real do Centro Tecnológico do Corpo de Fuzileiros Navais.Palavras-chave: Manutenção. Programação Evolucionária. Programa ção de Atividades. Problemas de Escalonamento. Simulação Computacional.

Abstract: Workshops that perform preventive and corrective maintenance repair face frequent changes in the characteris-tics of their demands. �is issue is even more critical when it comes to maintaining military equipment, subject to high levels of e�ort and performance. Consequently, those responsible for allocating available resources to repair activities over time deve-lop a considerable repertoire of knowledge that cannot be pro-perly formalized due to the speed with which they are generated and consumed. In this paper, we proposed a model of evolutio-nary programming associated with discrete simulation to gene-rate solutions for the programming of activities in a maintenance workshop. �e proposed model uses the tacit knowledge embe-dded in work plans previously formulated by experienced pro-duction programmers, to generate improved planning solutions, and was formulated based on the real case of the Marine Corps Technology Center.Keywords: Maintenance. Evolutionary Programming. Task Programming. Scheduling. Computer Simulation.

Manoel Carlos Pego Saisse, Sergio Medeiros da Nobrega, Rafael Novaes Lago, Lianderson Giorges Leite Rodrigues, Leonardo Amorim do Amaral


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1. INTRODUCTION

Maintenance workshops, which simultaneously per-form corrective and predictive activities, face great insta-bility regarding the characteristics of its demand (PAZ; LEIGH, 1994). �is issue is especially critical for mili-tary equipments, which are subjected to great e�orts and unforeseen situations. Furthermore, they must remain in permanent readiness in order to ensure national defense and safety (GOH; TAY, 1995). Flexible resources and pro-cesses are essential to meet demands of this sort, but they also broaden the alternatives courses of actions, which may increase the complexity of scheduling. In this kind of working environment, schedulers must be agile in redirect-ing their courses of action, quickly identifying more suit-able alternatives to ful³l the constant changes in demands. In these cases, much of the knowledge used to build the schedules is tacit, rather dynamic and, therefore, di¿cult to formalize, although it remains embedded in the plans that the schedulers build every day.

�is article presents an innovative model of evolution-ary programming associated with discrete simulation algo-rithm to generate scheduling solutions for maintenance activities. �e model is based on an initial set of schedules created by a user who is familiar with the work environ-ment in question (usually responsible for the scheduling of the maintenance workshop), supported by a discrete simulation algorithm.

2. THEORETICAL CONTEXTUALIZATION

Maintenance is classi³ed into three major types: pre-ventive, performed at predetermined intervals, calculated from the estimated probability of �aws considering proj-ects and history of equipment use; predictive, based not only on the probabilities of breakdown predicted by pre-ventive maintenance, but also on the conditions of use of the equipment; and corrective, performed after the occur-rence and identi³cation of failure, with the objective of reconditioning the equipment to their full working con-ditions (BEN-DAYA et al., 2009). Preventive and predic-tive maintenances may be planned in advance, as they are

inherently predictable and repeatable. Corrective mainte-nance, on the other hand, has two strong complexity com-ponents that directly a�ect the task of scheduling activities: uncertainties related to the moment when the damages or defects occur, with consequent unexpected �uctuations of the work load, and urgency, reducing the time available for planning (STOOP; WIERS, 1996). Corrective main-tenance for military equipment, in particular, is frequent and often di¿cult to predict, as they take part in real operations and exercises (GOH; TAY, 1995). Amik and Deshmukh (2006) classify the publications in the ³eld of maintenance management into six areas: optimization models, maintenance techniques, maintenance scheduling, performance, information systems, and policies. �e model presented in this article is related to maintenance schedul-ing, that is, the allocation of productive resources available to maintenance activities over a planning horizon. It is the last formal planning stage preceding the actual execution of maintenance operations. �is problem is addressed by the theory of scheduling. In the speci³c case of preventive maintenance workshops, job shop representation models are the most adequate ones among those used in this ³eld of study (PINEDO, 2016).

The theory of scheduling has evolved a lot over the last years, giving rise to optimization algorithms and models of greater applicability in real Flexible Job Shop environments (PINEDO, 2016), (where each service may follow a distinct routing and may be processed by alter-native groups of resources ). On the other hand, the use of classic models — linear schedule, mathematical pro-gramming , branch and bound, and constructive meth-ods — in maintenance activities has not been so broad, as they most of them were developed for production environ-ments where demand and available resources are relatively stable (AL-TURKI et al., 2014). Demand instability, a characteristic of most maintenance workshops (especially corrective maintenance ones), requires quick response to unexpected situations, and forces schedulers to build up a considerable amount of tacit knowledge (GUINERY; MACCARTHY, 2009). The speed and frequency with wich such kind of knowledge is generated, as well as its diversity, inhibit formalization, making it rather difficult to incorporate into traditional models proposed by the theory of scheduling.



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�is paper aims to explore this gap by proposing a model of evolutionary scheduling associated with discrete event simulation that generates improved scheduling solutions based on previous solutions build by a experienced sched-uler (that incorporates important tacit knowledge about the workshop) .

Evolutionary scheduling is inspired on the theory of evolution proposed by Charles Darwin. An iterative pro-cess departs from a set of initial valid solutions for the problem we want to tackle (initial generation). In each new iteration (generation), the algorithm chooses a set of promising solutions (selection) from the previous cycle recombine (crossover) and randomly alter (mutations) then to form a new generation (EIBEN; SMITH, 2003). As in nature, the successive selections, executed on the bases of the performance targets, followed by crossover-sand mutations, are expected to favor the survival and rep-lication of the solution fragments (genes) which result in better performance.

Chaudhry and Luo (2005) conducted a comprehensive review of the applications of genetic algorithms in produc-tion scheduling problems. Since then, speci³c genetic algo-rithm models for Flexible Job Shop have been suggested by a number of authors. Pezzella et al. (2008) proposed a genetic algorithm using speci³c methods for initial pop-ulation building, individuals’ selection and reproduction. Gao et al. (2006) presented a genetic algorithm that works associated with the Shifting Bottleneck classic method and a representation consisting of two vectors. Asadzadeh and Zamanifar (2010) developed a model in which two popu-lations of genetic algorithm evolve in parallel, and both the creation of the initial population and the evolution of the genetic algorithm are carried out by agents. Amirghasemi and Zamani (2015) proposed an asexual genetic algorithm model in which only mutations based on Tabu Search, with no crossover, occur.. Recently, Elgendy et al. (2017) proposed a genetic algorithm with traditional structures and a meth-odology of repair — to adjust the chromosome formed after crossover when it results in invalid solutions —, aiming to reduce crossover time.

Although some of these publications propose heuris-tics for the initial population, none of them mentions the participation of specialists or the use of tacit knowledge nor probabilistic methods to direct the choice of genes for

crossover. �ese are the most distinct characteristics of the model presented.

3. THE REAL REFERENCE ENVIRONMENT

�e model presented in this article was developed within the scope of a research project aimed to build a supporting tool for scheduling in military maintenance workshops, spon-sored by Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) and carried out by the National Institute of Technology (Instituto Nacional de Tecnologia – INT) in asso-ciation with the Marine Corps Technology Center (Centro Tecnológico do Corpo de Fuzileiros Navais – CTecCFN), which provided a real reference environment for the research, and a vast experience in management and maintenance of high-ly-technological equipment.

Founded in 1970 from the Marine Corps Supplies Center (Núcleo do Centro de Suprimentos do Corpo de Fuzileiros Navais), the CTecCFN has primary responsibility for the prompt employment and supply of speci³c equipment of Marine Corps (Corpo de Fuzileiros Navais – CFN), per-forming preventive and corrective maintenance services on light and heavy on-wheel vehicles, armored on-wheel and on-track vehicles, engineering equipment (tractors), communication devices, optronics, ballistic vests, light weaponry throughout the Brazilian Navy (Marinha do Brasil – MB) and, when determined, on Auxiliary Forces equipment such as the Military Police of the State of Rio de Janeiro (Polícia Militar do Estado do Rio de Janeiro – PMERJ). It constitutes one of the Science and Technology Institutes of Marinha do Brasil (Instituições de Ciência e Tecnologia da Marinha do Brasil – ICT-MB), whose objec-tive is to develop projects that meet the operational envi-ronment needs of the Marines and foster the Industrial Defense Base (Base Industrial de Defesa – BID), in line with the National Defense Strategy.

�e CTecCFN performs maintenance in military equip-ment for a large range of weaponry, from small to large armored vehicles, therefore possessing a vast diversity of equipment and personnel with multiple skills . �e work-shops are divided into seven major areas: motomechani-zation; machining; carpentry and foundry; armament and



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surface ³nishing ; car upholstering; metallurgy; and optics and electronics. Maintenance services are divided into two large groups:a. General Maintenance Program (Programa Geral de

Manutenção – Progem): preventive maintenance ser-vices performed on Marine equipment, which, by their very nature, may be scheduled and planned in advance; and

b. Corrective Maintenance Services (Programa Geral de Manutenção Extraordinário – Extra-Progem): services including maintenance of equipment that have su�ered any kind of unplanned damage.

�e evolutionary scheduling model described in this article was developed based on scheduling problems observed in the motomechanization workshop, the larg-est CTecCFN sector in terms of space and personnel. �is sector is responsible for the maintenance of o¿cial vehicles, from administrative to on-track armored ones. Productive resources are classi³ed into three categories: people, places, and equipment. �e workshop has both spe-cialized and generalist technicians with diversi³ed skills, able to carry out di�erent kinds of tasks, therefore, some tasks may be performed by many alternative groups of peo-ple. �e same goes for the boxes, speci³c locations where o¿cial vehicles park to be repaired. Schedulers are kept up-to-date about the abilities and pro³ciency of the avail-able technician, the suitability of each location and alter-native equipment to perform each service, and about the most appropriate moments to perform each maintenance task, considering temporal cycles like week and month. �is knowledge is not formalized, though intensely used in the construction of schedules. Each maintenance service is associated with an expected end date, which is not nec-essarily informed to the customers, but is used to estab-lish an objective related to time. �e main objective of the schedule is to maximize on timeon timeon time delivery.

4. THE EVOLUTIONARY SCHEDULING MODEL

The model proposed in this article follows the iter-ative cycle similar to the classic models of evolutionary

scheduling. The first step consists of creating a set of valid solutions to the problem, namely initial population. Each element of this set is submitted to a coding process that transforms it into a finite vector, namely chromo-some, that may have parts of its structure extracted and recombined to form new solutions. The following step, namely selection, forms parental pairs among the pop-ulational elements based in criteria related to specific performance indexes. The parental pairs are submitted to crossover, where parts of each parent are transferred to a new child-solution through a probabilistic process, until it becomes a complete new solution. Each set of child solu-tion formed at the end of the crossover process is called “generation”. A new generation is then decoded and eval-uated according to the criteria to be improved. The cycles of selection, crossover and evaluation are repeated until the maximum number of iterations or at least one solu-tion with the minimum predetermined performance is achieved. Each component of the proposed model in this article will be described next.

�e initial population is built by the scheduler with the support of a discrete simulation ³nite capacity sched-uling module and scheduling by ³nite capacity, inspired in the structure proposed by Costa (1996). �is module is connected to a database containing the most relevant characteristics of the work environment including infor-mation about the processing characteristics of the main-tenance operations and the alternative groups of resources that can perform them. . �e discrete simulation algorithm builds perfectly feasible work schedules, considering all restrictions and demands in the CTecCFN workshops. �e scheduler can make three management decision in order to create alternative work schedules: prioritization, change of resource work schedule and renegotiation of material delivery. Moreover, each solution created by the simulator is associated to a series of reports analyzing punctuality, use of resources and throughput times. �us, the sched-uler repeats the cycle of choosing a set of management decisions, executing simulations and evaluating the new solution until he judges that his ability to generate bet-ter solutions exhausted. During this process, the simula-tion module stores in its database all generated schedules. �e scheduler is oriented to diversify management deci-sions to a maximum, exploring available possibilities and



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thus, increasing the diversity of the solutions set. �e active and independent participation of the scheduler in this stage aims to capture tacit knowledge embed in the set of solutions created by him, that will be used as initial pop-ulation of the evolutionary schedule algorithm. Since this knowledge contributes to an improved on time delivery-and better resource utilization , the parts of the schedule responsible for the best results — promising genes, in evolutionary scheduling language — tend to survive the long evolution process.

Cheng et al. (1996) classify the coding methods for scheduling problems into two major categories: indirect, in which the chromosome consists of rules to guide the con-struction of an schedule; and direct, in which the schedule may be directly understood through symbols, with no need for transcription. �e time model uses a particularly direct coding method.

�e set of planned tasks that make up the schedule, sorted by their starting date was used to codify each alternative schedule (Chart 1). Each planned task is codi³ed according to the following list of data :1. Code of task (CodOper).2. Code of service the task belongs to (CodSer).3. Date/time when the task starts (IniOper).4. Date/time when the task ends (FimOper).5. List of codes of resources needed to process the task

(ListRec).6. �e latest possible starting date to a on time delivery of

the service (StartLatter).7. List of predecessor tasks in the maintenance service rout-

ing (ListAnt).

8. Expected delivery dates of external materials required for the task (if any) (ListMat).

Task codes, service codes, list of resources, and task pro-cessing start and end dates are classic elements used in the modeling of problems in the theory of scheduling. �e lat-est possible starting date to a on time delivery of service is calculated similarly to the back schedule proposed by the Material Requirement Planning (MRP), starting from the expected delivery date. �is calculation takes into consid-eration expected arrival dates of materials necessary for the execution of the tasks. �us, if the expected arrival date of material needed for processing a speci³c task (set by the pro-curement sector) is posterior to the starting date calculated by the back-scheduling process, the predicted arrival date of the material is considered as the earliest possible starting date for the best delivery date of the service. Figure 1 illus-trates the case of latest date calculation for operations of a maintenance service using forward and backward schedul-ing methods.

�e ellipses in Figure 1 represent the operations; the numbers in black, their expected processing time; and the numbers in red, the latest start dates calculated to ensure on time delivery of the service.

�e ³rst step of the evolutionary algorithm, selection for crossover, was conceived to form pairs of solutions with com-plementary characteristics in terms of punctuality. In most of the genetic algorithms researched, crossover pairs are formed randomly. If individuals forming a pair have too many sim-ilar characteristics, the childs solutions will be similar to their parents and will not bring variety to the population.

CodOper CodOper CodOper CodOper CodOper

CodSer CodSer CodSer CodSer CodSer

IniOper IniOper IniOper IniOper IniOper

FimOper FimOper FimOper FimOper FimOper

ListRec ListRec ListRec ListRec ListRec

StartLatter StartLatter StartLatter StartLatter StartLatter

ListAnt ListAnt ListAnt ListAnt ListAnt

ListMat ListMat ListMat ListMat ListMat

Chart 1. Schedule encoded in chromosome form.



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Figure 1. Latest possible date for on time delivery of the order, calculated by forward and backward scheduling methods.

Best possible delivery date: 02/05

Date prediction: 30/04

5 5

42 2

1 12

3 43

1 32

12 27

17

21 23

23 2425

17 2320

21 2422

Material expectedfor the 22nd

Forward schedule

Date prediction: 30/04

5 5

42 2

1 12

3 43

1 32

10 25

15

19 21

21 2223

15 2118

19 2220

Backward schedule

Crossovers could be more e¿cient if the “genetic distance” between individuals was considered when processing pair formation for crossover. A selection operator was proposed to form pairs of parents with complementary characteris-tics regarding delivery punctuality, thus increasing popula-tional diversity. �e complementarity degree between two individuals is measured by choosing a main one candidate and calculating the number of tasks in the following situa-tion in the pair :1. Initiated after StartLatter in the main candidate; 2. Initiated before StartLatter or exactly at this moment in

the other individual (the one tested for best complemen-tary of the main candidate) .

�e larger the number of operations in this situation, the higher the degree of complementarity of the candidate tested against the solution whose complement is being searched.

�is method forms as many pairs as there are individuals in the population, considering that each pair will generate a single individual child to be transmitted to the next genera-tion, as seen in Chart 2.

Should the selection operator ³nd more than one indi-vidual with the same complementarity degree in the popu-lation, a randomized tiebreaker is performed.

The crossover process between complementary pairs aims at forming new solutions from the combination of tasks from parental solutions. A tasks will be drawn to l form a child solution is only when it does not require any predecessors or when all its required predecessors (all of them) have already been drawn. The purpose of this rule is to prevent situations in which an operation would be inserted in the child solution at a time which requires their predecessor to have been programmed before the starting date of the planning horizon. In order to guide the draw, the set of tasks to be drawn is classified into two main groups:1. Tasks whose processing starts earlier or coincides exactly

with the latest possible start date for on time delivery of the service;

2. Tasks whose processing starts after the latest possible start date for a timely delivery of the service.

�e probability of drawing elements of the ³rst group is always higher than elements of the second one. Within each group, the probability of a task being drawn is increased as its start date approaches the latest possible date for a on time delivery of the service. During the draw, the sample mech-anism is constantly adjusted to maintain the distribution of probabilities described above.

When a task is drawn, the crossover operator tries to ³t it in the same time period and in the same resources it was occupying in their parents, without moving any tasks in the that have already been allocated for the child in formation. If this is not possible, the same discrete simulation algorithm, originally used to form initial solutions, is prompted to per-form a forward search in the planning horizon, until it ³nds a place that ³ts the earliest available time of the partially built work schedule. �is procedure is not restricted to the resources the task occupied in the parents from which it was copied, also seeking for free spaces in alternative resources. �is is possible because the database to which the discrete



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simulation algorithm is connected contains information on every possible set of resources able to carry out each task in each service.

�e child generated starts out as a blank planning horizon, being ³lled with parents’ tasks as they are drawn. Each main-tenance task is ³gured twice in the set of possible tasks to be reassigned to the child-solution, one in each of the parents forming the crossover pair. In a greatly diverse population, it is expected that the same task will be scheduled in di�er-ent ways (execution time, associated resources) depending on the chosen parent. During the treatment of each paren-tal pair, when a task is drawn, its correspondent (same task) in the other parent is eliminated from the set of tasks avail-able to be drawn.

It should be noted that the order of choice could have been conducted in a deterministic way according to the same criteria; however, preliminary tests showed that a probabilistic

methodology provides greater diversity to the population and broader exploration of possible solutions.

5. PRELIMINARY IMPLEMENTATIONS AND RESULTS

�is section describes the preliminary results obtained from the test performed during the ³rst implementation of the model depicted in the previous section. �e implementation was carried out using Visual Basic.NET programming language and PostgreSQL database. �e model consists of four blocks:1. Database;2. Discrete simulation algorithm with finite-capacity

scheduling;3. Interface; 4. Evolutionary schedule algorithm.

Chart 2. Example of pair with complementarity index equal to 2.

Complementary parent candidate

OperA OperB OperC OperA OperB

Serv1A Serv1A Serv1A Serv1B Serv1B

10/04 13h 13/04 10h 19/04 10h 17/04 08h 19/04 11h

12/04 17h 14/04 10h 22/04 17h 19/04 10h 21/04 15h

Maq1 Maq2 Maq3 Maq1 Maq2

10/04 08h 13/04 08h 16/04 15h 17/04 09h 19/04 11h

No external material





Main parent

OperA OperB OperC OperA OperA OperB

Serv1A Serv1A Serv1A Serv1C Serv1B Serv1B

10/04 13h 13/04 10h 16/04 11h 21/04 08h 23/04 11h 24/04 10h

12/04 17h 14/04 10h 20/04 17h 23/04 10h 25/04 10h 27/04 15h

Maq1 Maq2 Maq3 Maq1 Maq1 Maq2

10/04 08h 13/04 08h 16/04 15h 20/04 09h 17/04 09h 21/04 08h









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�e database stores the following information:a) Resources: means available to perform maintenance activ-

ities (site, operator or machine);b) Services: expected delivery dates, client;c) Execution: network of tasks which should be covered in

order to carry out the services, indicating ordering and technological precedence. �e necessary resources and basic material for the execution of each operation are included in the network, in addition to the expected exe-cution time of each tasks;

d) Schedule for material arrival: expected dates of arrival of basic materials necessary for the maintenance tasks;

e) Progress: information on the operations yet to be regis-tered in the database, but which have already been started or completed;

f) Decisions: managerial decisions made by the program-mer during the construction of work schedules;

g) Reports: calculated punctuality indexes, use of resources and crossover time for each schedule generated by the simulator;

h) Tasks: task execution schedule indicating resources used,start and end dates.

�rough the interface, users Interact with the sim-ulation algorithm and tests di�erent sets of managerial decisions. Each new set tested results in a new activity schedule, which is stored to compose the initial popula-tion of the evolutionary schedule algorithm. In order to test the performance of the proposed model, two sets of data were used:1. 20 services performed in 2014, totaling 300 tasks; and2. 35 services performed in 2013, totaling 500 tasks.

5.1. APPLICATION RESULTS ON DATASET 1

�e simulation algorithm was prompted 25 times, and the best punctuality index obtained was 60%, i.e., 12 services delivered up to the expected date.

�e evolutionary schedule algorithm was applied on the initial population of 25 solutions based on the simulation algorithm. �e best punctuality obtained converged to an 80% value in the eighteenth generation, which remained stable until the thirtieth generation, when the algorithm was interrupted.

5.2. APPLICATION RESULTS ON DATASET 2

�e simulation algorithm was prompted 19 times, and the best punctuality index obtained was 85.7%, i.e., 25 ser-vices deliveries up to the expected date.

�e evolutionary schedule algorithm was applied on the initial population of 19 solutions generated based on the sim-ulation algorithm. �e best punctuality obtained converged to an 82.8% value in the twenty-third generation, i.e., 29 services remained stable until the thirty-eighth generation, when the algorithm was interrupted.

Analysis of the top ten solutions proposed throughout the two cases showed that they shared 30 to 50% of the sched-uled tasks in the same periods/resources they appeared in the initial population. �is is an indicator that the tacit knowl-edge used to formulate these tasks was passed down through generations until the improved solutions were found.

6. CONCLUSIONS

An evolutionary schedule model associated to a discrete simulation algorithm was proposed to support task sched-uling of military equipment maintenance . It uses an initial population built by the current scheduler of the maintenance workshop where the project was developed . �e schedules that form the initial population include the tacit knowledge that the scheduler could not formalize due to the speed and dynamicity with which this knowledge is created. �e evo-lutionary schedule algorithm brings two innovative concepts to the ³eld of evolutionary scheduling applied to scheduling problems: complementarity of parents, as the crossover pairs are put together in an attempt to ³nd solutions that pres-ent complementary performance in deliveries; and selection of parts which will be transmitted to their children through probabilistic method, assuring that the parts with the best characteristics in each parent— regarding function-objective — will be the ³rst ones to be chosen.

�e preliminary results show that the process was able to improve the performance of punctuality in two sets of activ-ity schedules assembled with the help of the ³nite-capacity simulator. Furthermore, the tacit knowledge embedded in initial solutions is used by the process, which carries up to 50% of the original tasks contained in the initial population.



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AL-TURKI, U.M.; AYAR, T.; YILBAS, B.S.; SAHIN, A.Z. Integrated

Maintenance Planning in Manufacturing Systems, Springer Briefs in

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THE FIRST VERSION OF AN UNDERWATER ACOUSTIC SOFTWARE-DEFINED MODEM

FOR THE BRAZILIAN NAVYPrimeira versão de um modem acústico submarino

definido por software da Marinha do Brasil

Alexandre Geddes Lemos Guarino1, Fábio Contrera Xavier2, Luis Felipe Pereira dos Santos Silva3, Jefferson Osowsky4

1. Captain of Corvette (EN). Telecommunications Engineer. Master’s degree in Ocean Engineering from the Federal University of Rio de Janeiro. In charge of the Underwater Communication Division of the Department of Underwater Acoustics at the Institute for Marine Studies Admiral Paulo Moreira – Arraial do Cabo, RJ – Brazil. E-mail: [email protected]

2. Mathematician. Master’s degree in Ocean Engineering from the Federal University of Rio de Janeiro. Assistant to the Head of the Bioacoustics Division of the Department of Underwater Acoustics at the Institute for Marine Studies Admiral Paulo Moreira – Arraial do Cabo, RJ – Brazil. E-mail: [email protected]

3. Systems Analyst. Assistant to the Head of the Signal Processing Division of the Department of Underwater Acoustics at the Institute for Marine Studies Admiral Paulo Moreira – Arraial do Cabo, RJ – Brazil. E-mail: [email protected]

4. Electrical engineer. Master’s degree in Biomedical Engineering from the Federal Technological University of Paraná. Assistant to the Head of the Signal Processing Division of the Department of Underwater Acoustics at the Institute for Marine Studies Admiral Paulo Moreira – Arraial do Cabo, RJ – Brazil. E-mail: [email protected]

Abstract: �is work presents the progress that has been achieved by the Department of Underwater Acoustics at the Almirante Paulo Moreira Sea Studies Institute in the development of a simplex underwater acoustic software-de³ned modem. �is paper describes how the modem’s applications were implemented using C programming language, as well as its technical and functional features to date. �ree scenarios for testing are introduced to assess the modem’s performance in terms of bit error rate (BER) × signal-to-noise ratio per bit (Eb/N0) graphics.Keywords: Underwater Acoustic Communication. Digital Communication. Acoustic Modem. Software-De³ned Modem.

Resumo: Este trabalho tem o objetivo de apresentar os progressos alcançados pelo Departamento de Acústica Submarina (DAS) do Instituto de Estudos do Mar Almirante Paulo Moreira (IEAPM) no desenvolvimento de um modem acústico submarino simplex de³nido por software. São descritos neste artigo os diagramas em bloco dos apli-cativos de transmissão e recepção do modem, ambos implementados em linguagem de programação C, bem como suas características técnicas e funcionais até o presente momento. Três cenários de testes são apresen-tados para avaliar seu desempenho em termos do levantamento de cur-vas taxa de erro de bit (BER) versus relação sinal-ruído por bit (Eb/N0).Palavras-chave: Comunicação Acústica Submarina. Comunicação Digital. Modem Acústico. Modem De³nido por Software.

1. INTRODUCTION

In the past few decades, underwater acoustic com-munication, in terms of both short and long distances, has attracted the attention of research centers, research-ers and engineers in the telecommunications ³eld around the world (QUOZI; KONRAD, 1982; STOJANOVIC; PREISIG, 2009). It has been applied mainly in the transfer

of digital data between two points and, more recently, in the communication between nodes of underwater acoustic networks (SOZER; STOJANOVIC; PROAKIS, 2000). Furthermore, a few years ago, the development of sensor networks for use in the underwater environment began for di�erent applications, including: monitoring the e�ects of climate change, research on abyssal habitats, monitoring populations in coral reefs, monitoring water quality, o�shore

Alexandre Geddes Lemos Guarino, Fábio Contrera Xavier, Luis Felipe Pereira dos Santos Silva, Jefferson Osowsky


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engineering monitoring, and navigation assitance, among others (SENDRA et al., 2016).

�is large interest in underwater acoustic communica-tion is associated with the challenges that the researchers have found, especially those in the telecommunications ³eld, because the means of dissemination is extremely dis-persive (SENDRA et al., 2016). It produces signals that are spread out far over time, in milliseconds. Other chal-lenges include time-dependent and frequency-depen-dent attenuations of the received signal level (SOZER; STOJANOVIC; PROAKIS, 2000). It is worth mentioning that the acoustic waves are prefered for underwater com-munication (to the detriment of radiofrequency or opti-cal waves), because radio waves su�er drastic attenuations and there are di¿culties in aiming optical waves well in the underwater environment. It should be noted that the absorption of acoustic waves with frequencies commonly used for underwater communication is three times lower than that experienced by electromagnetic waves with the same frequencies (AYAZ et al., 2011).

�e main piece of equipment used for conducting under-water acoustic communications is the modem, which can be developed in several ways: standalone on a speci³c board, soft-ware-de³ned on a laptop or computer, or software-de³ned on a Single-Board Computer (SBC). Several “o�-the-shelf ” acoustic modems are available on the market, such as: the Teledyne Benthos underwater acoustic modem, LinkQuest’s SoundLink underwater acoustic modem, EvoLogics’ underwa-ter acoustic communication system, Aquatec’s AQUAmodem and DSPComm’s Aquacomm underwater wireless modem. Sendra et al. (2016) did an excellent job of compiling these devices and presenting a table with their characteristics, in addition to introducing the modem they developed, called ITACA, at the Universitat Politècnica de València. However, the best-known modem in the scienti³c community is called the WHOI Micro-Modem (FREITAG et al., 2005; SINGH et al., 2006; GALLIMORE et al., 2010). Other three low-cost and low-power modems that were builtin SBCs are presented in other studies (WILLS; YE; HEIDEMANN, 2006; BENSON et al., 2010; WU et al., 2012).

Furthermore, with the technological advances in the development of compact, low-cost Autonomous Underwater Vehicles (AUVs), commonly called micro-AUVs or (μAUVs), software-de³ned modems running on SBC-type platforms

are being shipped in these vehicles. This allows for the μAUVs to be controlled remotely by ³xed or mobile sur-face stations. Examples of this new approach adopted in submarine communications are described in other studies (RENNER; GOLKOWSKI, 2016; STOKEY; FREITAG; GRUND, 2005).

In 2011, the Department of Underwater Acoustics (Departamento de Acústica Submarina — DAS) of the Institute for Marine Studies Admiral Paulo Moreira (Instituto de Estudos do Mar Almirante Paulo Moreira — IEAPM), after successful experiments of transmitting digital data in its test tank, proposed the Submarine Communications Project (Comunicação Submarina — CSub) to the Secretariat of Science, Technology and Innovation of the Brazilian Navy (Secretaria de Ciência, Tecnologia e Inovação da Marinha do Brasil — SecCTM) - which is now called the Directorate General for Nuclear and Technological Development of the Navy (Diretoria-Geral de Desenvolvimento Nuclear e Tecnológico da Marinha — DGDNTM). �e project will last ten years and aims to develop a complete underwater acoustic com-munication system using national technology and owned by the Brazilian Navy. Its main objective is to communicate between a base station and a submarine through a simplex software-de³ned modem developed by the DAS team called Modem-CSub (OSOWSKY et al., 2014a; 2014b).

�erefore, this article has the objective of presenting the block diagrams of the transmission and reception applications, as well as the performance curves of the Modem-CSub. For example, the bit error rate (BER) versus signal-to-noise ratio per bit (Eb/N0), obtained by means of digital data transmis-sions/reception carried out in communication channels that:1. were subject to only the presence of white Gaussian addi-

tive noise (AWGN);2. were subject to fading with impulsive channel response

obtained through Bellhop simulations; and3. had a channel impulse response estimated from trans-

missions in the DAS test tank.

2. OBJECTIVES

The objective of the project “CSub - Submarine Communications”, under grant nº TC53000/2011- 001/2011 of the DGDNTM, as initially proposed, is the development



| 78 |

of an underwater acoustic communication system using safe, reliable, and scalable acoustic methods.

It should be emphasized that the focus of this work was the development of a prototype of an acoustic modem de³ned by software (modem acústico de�nido por software — MADS) up until its ³rst version, as well as its results. �is work does not include a detailed presentation of the data transmission stations used by Modem-CSub during the tests, or other works carried out by the project team, such as the devel-opment of an arrangement of six projectors and a mobile transducers calibration system (GUARINO; FLORENCIO; SARAIVA, 2016).

3. METHODOLOGY

�roughout the project, the submarine acoustic modem went from a technical speci³cation, de³ned from opera-tional requirements and conclusions drawn from meetings with DAS team members, to the concrete implementation of two applications:1. cstx.exe: an application executed by command line via

Windows Shell and intended to encode a message entered by the user or contained in some text or binary ³le, and transmit it as an analog electrical signal through the out-put of the computer’s audio card or through the analog output of a National Instruments (NI) Data Acquisition (DAQ) device;

2. csrx.exe: an application executed by command line via Windows Shell to decode an analog electrical signal acquired via the input of a computer’s audio card or via the analog input of an NI DAQ device.

Initially, the coding/decoding, modulation/demodulation functions of the messages were implemented and tested in an MATLAB environment from digital signals recorded in a wave format. Once the functions of the capture were val-idated, bu�ering and digital signal processing stages were implemented in C programming language.

Here, it should be noted that most of the complexity in developing a MADS is in the reception subsystem, since the received electrical signal is contaminated by noise, and attenuated and distorted by the communica-tion channel through which the transmitted signal has

propagated. This contributes to the appearance of errors in the decoded message. Implementing digital signal pro-cessing techniques in the modem receiving application reduces these errors.

Brie�y, the MADS developed up until now has the fol-lowing characteristics:1. con³guration of modem parameters via a text ³le;2. reception and transmission of signals via Windows Audio

System (WAS) or NI-DAQmx;3. processing of the signals received by the MADS receiver

in real time;4. frequency-shift keying (M-FSK) modulation that is not

coherent with M mutually orthogonal carriers;5. frequency diversity to mitigate the channel fading e�ect;6. Finite Impulse Response (FIR) digital pass-band ³lter

at receiver input;7. matrix interleaver to mitigate burst error;8. precise bit error correction (FECC) via convolutional

code;9. adaptive receiver wake-up system;10. equalization of the received packet via a Wiener ³lter;11. recording of the received signals in wave ³les.

3.1. TRANSMISSION APPLICATION: CSTX.EXE

In this section we will brie�y explain how the cstx.exe application operates. Its block diagram is shown in Figure 1A.

As mentioned, the transmission step, when considering the signal processing, does not require a high level of com-plexity either in implementing its code or when involving digital signal processing technique applications.

A set of input bits is encoded (bits are redundant via a convolutional code and are scrambled by an interleaver), modulated in M-FSK, and packaged in a subset of N sym-bols per packet. A chirp-type signal is added to delimit the beginning and end of each packet. While these processes are performed, the resulting signal is appropriately sent to a First In, First Out (FIFO) memory bu�er. �e output of this bu�er sends the signals to the audio device, which will transmit the signal to the transmission system.

3.2. RECEIVING APPLICATION: CSRX.EXEIn this section we will brie�y explain the operation of the

csrx.exe application. Its block diagram is shown in Figure 1B.



| 79 |

M

M

PACK#i identified

input bits

encoderLFM signal

(chirp)convolutional

code

interleavermod

(M-FSK) Packer

SW: Thread #1HW: acquisition board

inte

rnal

bu�

er

DAC

analog signal (projector)

limited bu�er

t=0

bu�er temporal em memória

LFM

#N

+1

LFM

#N

LFM

#4

LFM

#3

LFM

#2

LFM

#1

PACK#N ... PACK#3 PACK#2 PACK#1

A

B

set $AM=0, if $DL<$THset $AM=1, otherwise

set $TH=K+$NP

signal LFM(chirp)

comparator

$DL10 log

(RMS)210 log

MAX

SW: Thread #1 (SAM=0)


HW: acquisition board


temporary bu�er on file

limited bu�er

unlimited bu�er

t

t-T/2

t-T

t=0

and {t–T / 2: t–T}

bu�

er in

mem

ory

and {t: t–T / 2}

$AM=0

$AM=0

$AM=1

FIRfilter

FIRfilter

inte

rnal

bu�

er

ADC

analog signal (hydrophone)

set $NP

LFM

#1

LFM

#2

LFM

#3

LFM

#4

LFM

#N

LFM

#–1

PACK#1 PACK#2 PACK#3 ... PACK#N noise

LFM signal(chirp)

PACK#i1<=i<=N

spline Wiener filter

demod(M-FSK)

deinter leaves

Viterbi

output bits

set $AM=0

Yeslast

chirp?LFM#i

1<=i<=N+1

No, set i=i+1

decoder

Figure 1. Block diagram of software-defined acoustic modem applications: (A) cstx.exe; (B) csrx.exe.



| 80 |

Once begun, this application receives the signal scanned by the audio card from a hydrophone. It then stores it in a memory bu�er of T seconds long. �is bu�er can be viewed as a window of T seconds that travels along the “discrete time axis” at a rate of fs samples/second, where fs is the sampling frequency of the signal acquisition device.

Initially, because no message was transmitted, the content of the bu�er will be in a sequence that represents the ambi-ent noise of the underwater channel. Its bottom, from t − T/2 to t − T, is then parsed by ¬read #2 of csrx.exe, which calcu-lates, in dB, the average ambient noise power at the moment. �is positive real value is stored in the $NP variable. �e process is performed in real time while the variable $AM equals zero.

In ¬read #1, while $AM is equal to zero, the upper part of the bu�er is analyzed. It searches for a chirp signal, which would mean the beginning of the arrival of a message in this sub window of the temporal window. �is search takes place through the cross-correlation function in the time domain. It then searches for its absolute maximum, denominated $DL, given in dB. $DL is used as a reference value in a compar-ator whose second input is given by the value contained in the variable $TH, which is the sum of $NP, mean power of the noise in the communication channel and the constant K de³ned by the user in the con³guration ³le of the modem. If $DL≥$TH, the unit value is assigned to $AM, thus acti-vating the execution of ¬read #3, which e�ectively performs the demodulation and decoding process of the received signal.

Once the ³rst chirp is identi³ed, the incoming digi-tal signals are stored in a ³le bu�er. �e search for the other chirps will occur in this bu�er, no longer in memory. In ¬read #3, a second cross-correlator performs this search, marking the beginning and end of each received packet. First, each packet is interpolated by means of a cubic spline function to mitigate the Doppler e�ect. A Wiener ³lter is then applied throughout the packet in order to equalize the received sig-nal, thus reducing the fading e�ects caused by the commu-nication channel. After these steps, the symbols are sepa-rated, demodulated and decoded. In the demodulation, the frequency diversity allows the symbol to be detected by two distinct frequencies, reducing the error caused by channel fad-ing. In the decoding step, the Viterbi algorithm attempts to correct erroneous bits by means of redundancy added to the transmitter. �e use of the deinterleaver prior to the Viterbi algorithm increases its e¿ciency by separating a sequence of

contiguous erroneous bits. Finally, there is a sequence of output bits, which must be equal to the sequence of transmitted bits. With the identi³cation of the last packet, the variable $AM is zeroed, and the modem is taken back to channel listening mode. For example, this might include running �reads #1 and #2 and using the bu�er in memory.

4. RESULTS

�e results of this work were obtained via laptop and USB audio card with a sampling rate of 48 ksps and a quantiza-tion of 16 bits/sample. �e transmitter sends the message to the audio output of that card, which is then acquired by the receiver through the audio input of the same card. An audio cable connects the input and output terminals. In relation to the communication channel, three scenarios were evaluated for the BER × Eb/N0:• C1: the channel is subject to noise only AWGN: y(t) =

x(t) + η(t);• C2: the channel is obtained by Bellhop and is subject to

noise AWGN: y(t) = h(t) ∗ x(t) + η(t);• C3: the channel is estimated from a chirp signal acquired

in the test tank and is subject to noise AWGN: y(t) = h(t) ∗ x(t) + η(t).

Where y(t), x(t), h(t) and η(t) are the received and trans-mitted signals, the impulse response of the communica-tion channel, the mean zero AWGN noise, and σ 2=0.,001, respectively .

�e Eb/N0 value obtained in the scenarios cited for the evaluation of the performance curves of the Modem-CSub was calculated in real time using the receiving application described. �e equation 1 presented in Osowsky et al. (2014a) was utilized with the insertion of the term D, which de³nes the order of the frequency diversity (RAUT; BADJATE, 2013; RAPPAPORT, 2002) used in the proposed underwa-ter acoustic communication system, i.e.,

Eb

N0

Eb

N0– 10 · log (D)=

D (1)

Without losing generality and in order for the notation to be simple, from now on the subscript |D in Eb/N0 in the quoted equation will be omitted, so that any mention of the signal-to-noise



| 81 |

ratio per bit is related to one being calculated with the frequency diversity term included. �e tests were run as follows:1. an uniformly distributed 1728-bit sequence {0, 1} was

generated to be transmitted. Note that the number of transmitted bits is double that sequence, since the code rate value used in the convolutional code was 1/2;

2. the AWGN noise in y(t) was added by the receiver;3. for the signal x(t) to be in�uenced by channel h(t) in sce-

narios C2 and C3, the transmitter convoluted x(t) with the desired h(t) before sending it to the audio card;

4. modem performance was raised for 8-FSK modula-tion with frequency diversity (D=2), with no guard time between symbols (234 bps) and with guard time equal to 12.8 ms (117 bps);

5. the input sequence was transmitted 300 times, decreasing the amplitude of the signal to the audio card in each step. �us, because the AWGN noise entered by the receiver was constant, the Eb/N0 value decreased, resulting in a larger BER.

�e BER × Eb/N0 curves of the modem performance for scenario C1 are shown in Figure 2. �e impulse response function h(t) of scenario C2, both in the time domain and in the frequency domain, as well as its performance curves, are shown in Figures 3 and 4, respectively. Finally, the function h(t) and the curves BER × Eb/N0 for the scenario C3 are shown in Figures 5 and 6, respectively. It should be noted that the channel impulse response to scenario C1 was omitted,

Figure 2. Modem performance for scenario C1.

8-FSK with frequency diversity (M08wDiv)Channel: awgn --- Tg=0.0 ms --- FECC active: no

8-FSK with frequency diversity (M08wDiv)Channel: awgn --- Tg=12.8 ms --- FECC active: no

8-FSK with frequency diversity (M08wDiv)Channel: awgn --- Tg=0,0 ms --- FECC active: yes

8-FSK with frequency diversity (M08wDiv)Channel: awgn --- Tg=12.8 ms --- FECC active: yes

100

10-1

10-2

10-3

0 2 4 6 8 10 12 14 16 18 20Eb/N0 (dB)

0 2 4 6 8 10 12 14 16 18 20Eb/N0 (dB)

Bit

err

or

rate

100

10-1

10-2

10-3

Bit

err

or

rate

100

10-1

10-2

10-3

0 2 4 6 8 10 12 14 16 18 20Eb/N0 (dB)

0 2 4 6 8 10 12 14 16 18 20Eb/N0 (dB)

Bit

err

or

rate

100

10-1

10-2

10-3

Bit

err

or

rate

no equalization (NoEqu) with equalization (w/Equ) theoretical (with diversity, D=2)

A

C

B

D



| 82 |

Figure 4. Modem performance for scenario C2.

Figure 3. Underwater communication channel calculated from Bellhop.

Impulse Response Function Impulse Response Function

Time (s) Frequency (Hz)

Frequency (Hz)

7.000

6.000

5.000

4.000

11.000

10.0

00

9.000

8.000

7.000

6.000

5.000

4.000

11.000

10.0

00

9.000

8.000

0.05A B

0.04

0.030.02

0.010

–0.01

–0.03–0.04

–0.05

–0.02

h[n]

0.0020

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.018

0.02

–40–30–20–10

0

–30–20–10

100

Gai

n (

dB

)P

hase

(ra

d)

8-FSK with frequency diversity (M08wDiv)Channel: sim-trac --- Tg=0.0 ms --- FECC active: no

8-FSK with frequency diversity (M08wDiv)Channel: sim-trac --- Tg=12.8 ms --- FECC active: no

8-FSK with frequency diversity (M08wDiv)Channel: sim-trac --- Tg=0.0 ms --- FECC active: yes

8-FSK with frequency diversity (M08wDiv)Channel: sim-trac --- Tg=12.8 ms --- FECC active: yes

100

10-1

10-2

10-3

0 2 4 6 8 10 12 14 16 18 20Eb/N0 (dB)

0 2 4 6 8 10 12 14 16 18 20Eb/N0 (dB)

Bit

err

or

rate

100

10-1

10-2

10-3

Bit

err

or

rate

100

10-1

10-2

10-3

0 2 4 6 8 10 12 14 16 18 20Eb/N0 (dB)

0 2 4 6 8 10 12 14 16 18 20Eb/N0 (dB)

Bit

err

or

rate

100

10-1

10-2

10-3

Bit

err

or

rate


A

C

B

D



| 83 |

Figure 5. Communication channel estimated from a chirp signal acquired in the test tank.

Figure 6. Modem performance for the C3 scenario.

8-FSK with frequency diversity (M08wDiv)Channel: tank --- Tg=0.0 ms --- FECC active: no

8-FSK with frequency diversity (M08wDiv)Channel: tank --- Tg=12.8 ms --- FECC active: no

8-FSK with frequency diversity (M08wDiv)Channel: tank --- Tg=0.0 ms --- FECC active: yes

8-FSK with frequency diversity (M08wDiv)Channel: tank --- Tg=12.8 ms --- FECC active: yes

100

10-1

10-2

10-3

0 2 4 6 8 10 12 14 16 18 20Eb/N0 (dB)

0 2 4 6 8 10 12 14 16 18 20Eb/N0 (dB)

Bit

err

or

rate

100

10-1

10-2

10-3

Bit

err

or

rate

100

10-1

10-2

10-3

0 2 4 6 8 10 12 14 16 18 20Eb/N0 (dB)

0 2 4 6 8 10 12 14 16 18 20Eb/N0 (dB)

Bit

err

or

rate

100

10-1

10-2

10-3

Bit

err

or

rate


A

C

B

D

Impulse Response Function Impulse Response Function

Time (s) Frequency (Hz)

Frequency (Hz)

7.000

6.000

5.000

4.000

11.000

10.0

00

9.000

8.000

7.000

6.000

5.000

4.000

11.000

10.0

00

9.000

8.000

0.050.04

0.030.02

0.010

–0.01

–0.03–0.04

–0.05

–0.02

h[n]

0.0020

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.018

–80–60–40–20

0

–80–60–40

0–20

A B

Gai

n (

dB

)P

hase

(ra

d)



| 84 |

since h(t) = δ(t), where δ(t) is the Dirac delta function, that is, a �at frequency response in the band used. In the graphs of Figures 2, 4 and 6, those identi³ed as (A) and (B) illus-trate the results before the bit sequence passes through the error corrector (Viterbi algorithm).

�ose identi³ed as (C) and (D) show the results after the bit sequence passes through the Viterbi algorithm. In addition, the blue curves refer to the performance of the Modem-CSub without the application of the equalizer. �e curves in red refer to the performance with the appli-cation of the equalizer. �e green curves show the theoreti-cal results for the AWGN 8-FSK noise modulation (Figure 2) in addition to those that were also subject to a Rayleigh distribution (Figures 4 and 6).

For scenario C2, the simulation was performed from the out-put of amplitudes and delays of the Bellhop ray tracing model. Calculations were made for the center frequency of 7.5 kHz.

5. CONCLUSION

�is work presented the development and evaluation of the ³rst version of a simplex underwater acoustic modem de³ned by MB software. �e results show that the development of the modem is in line with the phases and goals of the “CSub - Submarine Communications” project of IEAPM/DGDNTM. �e evaluation of the modem also shows its great potential in military and civil applications. In civil applications, the modem can be used, for example, in the command and con-trol of AUVs, in o�shore activities, in communications with oil prospecting equipment, and in the area of environmental

monitoring, by providing real-time information on water quality and conditions in hostile regions. In addition, the modem has been increasing the expertise of MB’s technical sta� in this strategic area of National Defense, allowing the development of new technologies that are 100% Brazilian.

6. ACKNOWLEGMENTS

�e authors of this work and the IEAPM DAS thank the National Council for Scientific and Technological Development (CNPq) for providing technological devel-opment scholarships and innovative extension through grants nº 381984/2012-5/DTI, nº 383030/2014-5/DTI and nº 383094/2014-3/DTI; the Financing Agency for Studies and Projects (Financiadora de Estudos e Projetos—Finep) for the ³nancial support granted under contract/agreement nº 01.13.0421.02(1345/13); and the DGDNTM for the ³nancial support for the project “CSub - Submarine Communications”, process TC 53000/2011-001/2011.

Part of this work was presented at the XI Meeting of Technology in Underwater Acoustics - XI ETAS, 2014, Rio de Janeiro (RJ), Brazil.

This work has received the “Sovereignty for Science” award, in its ³rst edition, granted by the DGDNTM and sponsored by the Conrado Wessel Foundation (Fundação Conrado Wessel FCW). For this reason, the authors of this paper thank all those, military personnel and civilians, who directly or indirectly contributed, in the past and present, to the success of the “CSub - Submarine Communications” project. Bravo Zulu.

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RESOLUTION OF PORT-STARBOARD AMBIGUITY

IN A TOWED ARRAY OF HYDROPHONESResolução da ambiguidade boreste-bombordo

em arranjo de hidrofones rebocado

Stilson Veras Cardoso1

1. Technologist of the Navy’s Research Institute (IPqM) – Rio de Janeiro, RJ – Brazil – E-mail: [email protected]

Abstract: �is work presents a method for the resolution of the port-starboard ambiguity problem using a towed array of hydro-phones: the twin-line planar array. Starting from the mathemat-ical model of this array, MATLAB simulations were carried out in order to assess its performance in the frequency range 10 to 1,000 Hz, and determine the steering limits of the beam pattern. A system composed of a signal generator and a twin-line planar array was programmed to evaluate the signal processing by the array. �e system emulates a deterministic acoustical signal emit-ted by a target and a transmission medium. �e beamforming of the received signal uses the delay-and-sum method. �e tar-get’s location was estimated e�ectively based on the time-aver-age power and the frequency-and-angular spectrum of the beam-formed signal.Keywords: Sonar. Port-Starboard Ambiguity. Towed Array of Hydrophones.Twin-Line Planar Array.Simulations in MATLAB.

Resumo: Este trabalho apresenta um método para a resolução do pro-blema da ambiguidade boreste-bombordo em arranjo de hidrofones rebocado: o arranjo plano em dupla linha. A partir do modelo mate-mático desse arranjo foram realizadas simulações em MATLAB® (MathWorks Inc.) para avaliar seu desempenho na faixa de frequên-cia de 10 a 1.000 Hz e determinar os limites de giro do diagrama de irradiação. Um sistema composto de um gerador de sinal e um arranjo plano em dupla linha foi programado para avaliar o processamento de sinal pelo arranjo. O sistema simula um sinal acústico determinístico emitido por um alvo e um meio de transmissão. A conformação do sinal recebido emprega o método de atraso-e-soma. A posição do alvo foi estimada de forma efetiva com base na potência média e no espec-tro de frequência-e-angular do sinal conformado.Palavras-chave: Sonar. Ambiguidade Boreste-Bombordo. Arranjo de Hidrofones Rebocado. Arranjo Plano em Dupla Linha. Simulações em MATLAB.

1. INTRODUCTION

Compared to hydrophone arrays mounted in the hull of the ship, such as cylindrical and �ank arrays, towed arrays allow decoupling the self noise from the signal received from targets, thus increasing signal-to-noise ratio (SNR). In addition, their physical dimensions are not restricted to the length of the hull, allowing an improvement in the directivity. Figure 1 shows the basic structure of a towed sonar, based on the Tow�ex architecture (LASKY et al., 2004), comprising the

array of hydrophones, the towing cable, and the tail. �e array is encapsulated in a hose in order to protect its electronics from sea water and physical shocks. �e hose is �exible, so as to avoid noise in form of resonance (URICK, 1983). It also contains a layer of oil which provides buoyancy, stabilizing the array horizontally and thus reducing drag (LASKY et al., 2004). �e tail is appended at the end of the array to avoid a whipping e�ect over the array (URICK, 1983).

�e towing cable is long enough to place the array below the thermocline (see sound speed pro³le in Figure 1), in the

Stilson Veras Cardoso


| 87 |

far-³ eld of the ship’s radiated self noise, where a portion of this noise is dissipated by propagation loss (LASKY et al., 2004).

The problem of port-starboard ambiguity stems from the symmetry of linear-arrays’ beam pattern, as shown in Figure 2, illustrating a linear array being towed by a submarine (seen from above). The horizontal beam pat-tern in the XY plane has a main lobe (hatched in blue) and its image, and it is being steered to search for tar-gets. For a target located at ψs = 135° (port side), the array’s response will be the same for ψ’ equal to both 45° (target at starboard side) and 135° (target at port side). Since the sonar output is the same for identical array responses, the sonar operator cannot discrimi-nate between the target being at port or starboard side, or whether there are two targets.

� e method addressed by this work as a solution for the problem of port-starboard ambiguity is the twin-line planar array, which is modeled by two linear arrays in parallel com-posed of N omnidirectional, identical point-elements, and weighted by complex weights (ZIOMEK, 2016). Figure 3 illustrates an array with six elements per line positioned in the XY plane, where dx and dy are the interelement spacing in the X and Y axes, respectively (ZIOMEK, 2016).

� e beam pattern of the twin-line planar array located in the far-³ eld of a sound-source, as a function of frequency ƒ and dimensionless direction cosines in the X and Y axes, respectively u and v, is given by Ziomek (2016):

∑πλ

πλ

= − − −=

D f u v a f S f u u d b f v v n dXn

Y

n

N

( , , ) 4 ( ) ( )cos ( ') ( )cos 2 ( ')( 0.5)11

/2

(1)

∑πλ

πλ

= − − −=

D f u v a f S f u u d b f v v n dXn

Y

n

N

( , , ) 4 ( ) ( )cos ( ') ( )cos 2 ( ')( 0.5)11

/2

Figure 2.Port-starboard ambiguity.

ψs = 135°

Port Side

X

ψ’ = 45°Starboard Side

ψs = 45°

YZ

Figure 1.Towed hydrophone array.

Casing

Tail

Z

X

Y

Hydrophone array system

Towing cableSelf-Noise

Near Field

Propagation loss

Far Field

Ray

Thermocline

c(z)

Source: Adapted from Lasky et al. (2004).



| 88 |

whereS(ƒ) is the complex, element sensitivity function,a1( f ) = a-1( f ) are the amplitude weights in the positive and negative X directions, respectively,

= =−b f b f n Nn n( ) ( ), 1, 2,..., (2)

are the amplitude weights in the positive and negative Y directions, respectively, λ is the wavelength of the signal irra-diated by the target, and the dimensionless direction cosines u and v, and respective beam pattern steering values, u’ and v’, are given in terms of spherical angles θ, ψ, θ’, and ψ’ by:

θ ψ=u sin cos (3)

θ ψ=u ' sin 'cos ' (4)

θ ψ=v sin sin (5)

θ ψ=v ' sin 'sin ' (6)

�e array can be designed for a given operating fre-quency range in terms of its upper limit (minimum wave-length). For this value of λ, the beam pattern is free of ambiguity and the required interelement spacing is given by (ZIOMEK, 2016):

λ=dY / 2min (7)

λ=dX / 4min (8)

�is con³guration was deployed to study the behavior of the array beam pattern, as well as in the simulations, to be discussed in the following section.

2. RESEARCH METODOLOGY

Initially the array was studied in terms of the beam pat-tern behavior as a function of frequency and beam-steer angle. Starting from the optimum frequency used to dimension the array, which would theoretically resolve the port-starboard ambiguity, the beam pattern was calculated and plotted for successively lower frequencies, in order to determine the minimum operating limit. Next the in�uence of steering of the beam pattern was investigated, and the operating limit was determined.

In the second part of the research the aim was to evalu-ate the array’s ability to estimate the target’s location whose coordinates are known. A system consisting of a signal gen-erator and a twin-line planar array was therefore programmed in MATLAB® (MathWorks Inc.). Unlike the previous trials, the tests were performed using just one value of frequency (1,000 Hz) for the signal, which is the one set to dimension the array for rejecting port-starboard ambiguity. Basically, the sig-nal generator emits an acoustic signal and simulates a trans-mission medium. �e resulting acoustic signal is sent to the array, which transduces it into an electric signal, performs the beamforming, and calculates two outputs: time-average power and frequency-and-angular spectrum, both used to estimate the target location. Figure 4 shows the system components.

�e ³rst block of the signal generator is the acoustic source, which generates a CW (continuous wave) pulse, 500 ms long, at 1,000 Hz and sampled at 10 kHz. �e adopted model is an omnidirectional point-source, and its spherical coordinates (rs, θs and ψs) are adjustable and de³ned with respect to the center of the array as the origin. In the simulations, the radial distance from the source to the center of the array was set to 500 m. In this model, the pulsating source displaces an uni-form �uid volume in all directions at a constant rate, and the

Figure 3.Twin-line planar array.

X

YZ 0

dX

dY

Source: Adapted from Ziomek (2016).



| 89 |

volume � ow rate, in m3/s, provides the unit to the amplitude of the signal. For simulation purposes it was used the radi-ated noise level (RNL) read at 1,000 Hz and 1 m from the frequency response (acoustic signature) of a typical diesel submarine sailing at low speed (4 knots) — 120 dB re 1μPa (LURTON, 2002). Given the operational frequency ƒ(Hz) and the � uid density ρo, approximately 1,000 kg/m3 for sea water, one can calculate the source strength’s amplitude using the following expression (based on KINSLER et al., 2000):

P 1ρ

= ×=Afr m re f

RNL f| 2 010

( )/20 (9)

wherePref, equal to 1μPa, is the reference pressure amplitude.

� e transmission medium is modeled as unbounded, i.e., without interaction (re� ection, refraction or absorption) with the bottom or surface of the sea, viscous (absorptive) and homogeneous, i.e., the speed of sound propagation c(m/s) is considered constant, independent of depth, temperature or density, so that the propagation is rectilinear, without refraction. � e value of c for the simulations was 1,500 m/s. � e medium modi³ es the radiated acoustic signal through attenuation due to absorption and propagation loss (in this

work considered spherical propagation), and introduction of propagation time-delay. � ese variables depend on the distance Rm,n between the acoustic source and each element (m, n) of the planar array, while the time-delay depends also on the sound speed. � e absorption coe¿ cient depends on frequency, temperature and salinity, but can be expressed by the following approximation, which was used to calcu-late the attenuation at the operating frequency of 1,000 Hz (KAPOLKA, 2015)

α =+

++

+ × −fF F

F'( ) 0.080.9

303000

4 102 24 2 (10)

To the signal modi³ ed by absorption, propagation atten-uation and time delay is further added ambient noise, result-ing in the acoustic signal used as input for the planar array. Ambient noise usually consists predominantly of sound produced by merchant ships and resulting from the sea sur-face disturbance caused by wind and rain (URICK, 1983). For lack of a model that could be used to simulate such noise in this work, a white Gaussian noise generator was employed. � e noise was generated with zero mean, and the variance was calculated for di� erent values of SNR considered in the sim-ulations. In addition, anticipating that the model of the array includes the receiver self noise, this is also approximated by

Figure 4.Signal generator system + twin-line planar array.

Signal generator

Acoustic source

Medium

UnboundedHomogeneous

Attenuation

Time delay

Ambient noise

Z

θsr s

Y

XY

ψsX

Source

Twin-lineplanar array

Transduction(Sensor Frequency Response)

Beamforming

SNRReceiver Noise

+Ambient noise

Resulting signal Spectrum

Time-Average Power

Estimated Freq-and-Angular

Spectrum Steering ψ’

(θs, ψs)

Source: features based on Ziomek (2016).



| 90 |

random noise generated by a MATLAB function. �erefore both noises were included as a single random signal in the planar array module.

�e array module implements two main functions: trans-duction of the acoustic signal coming from the medium into an electrical signal, and beamforming. �e module outputs are the beamformed signal in the time domain and in the frequency domain (frequency spectrum). �ese signals are used to estimate the target location.

Recalling that the input acoustic signal is a matrix com-posed of m x n time-delayed signals due to path di�erences for each array element with rectangular coordinates (xm, yn) the transduction must be also performed for each element of that matrix. �e transduction is de³ned as the product of the frequency spectrum of the acoustic signal components and the receiver sensitivity function S(ƒ) of the correspon-dent array element — which is the same for all elements, once the array model assumes that they are identical. In the simulations, the function S(ƒ) was obtained from the receiver sensitivity level RSL(ƒ) characteristics of a commercial trans-ducer, RSL(ƒ) in dB re RSref, vs. frequency (Hz), with RSref equal to 1V/μPa. According to the curve, RSL(ƒ) is approx-imately constant and equal to 167 dB re 1V/μPa within the range of 40 to 1,000 Hz (CETACEAN RESEARCH TECHNOLOGY, 2016). Applying this RSL value to the following expression, the receiver sensitivity of the elements was obtained in V/μPa:

=RS f RSrefRSL f( ) 10 ( )/20 (11)

And using this result in the expression below (ZIOMEK, 2016), the magnitude S(ƒ) was determined:

π ρ=S f f RS f| ( )| 2 ( )0 (12)

Corruption of the signal by both ambient and receiver noise is implemented in the planar array module, and it is applied to the transduced electric signal. In general, thermal noise is the typical noise source in the receivers; but in towed sonars �ow noise also contributes to the resulting noise in the reception. �e simulations were carried out for three cases of signal-to-noise ratio (SNR): +3 dB, 0 dB and -3 dB, and with Gaussian additive noise with zero mean. In order to calculate the additive noise required to corrupt a sampled electrical

signal ym,n(l ) with a given SNR, ³rst a random sequence with the same pulse duration, variance one and zero mean is gen-erated. �ereafter, to this random sequence the required stan-dard deviation for the correspondent SNR is applied using the following expression, given in terms of the time-average power Pavg y lm n, ( ),

of the signal ym,n(l ):

σ × −Preq = a vg y lSNR

m n10, ( )

/20,

(13)

wherethe time-average power of the signal ym,n(l ) with L samples is de³ned by:

∑==

−

PL

y lavg y l m nl

L

m n

1 | ( )|, ( ) ,2

0

1

, (14)

�e random sequence of each element of the array is generated with a di�erent seed. Although noise generators are, in practice, pseudo-random, this procedure reduces the statistical dependence among the signals of the elements.

Beamforming is accomplished by calculating the prod-uct of the frequency spectrum estimate of the set of (m, n) noise-corrupted signals — calculated by discrete Fourier transform (DFT) — and the complex weights cm,n, as the angles θ’ and ψ’ vary during beam-steering.

�e complex weights are given by the following expres-sion (ZIOMEK, 2016):

= π τ−c f a em n m nj f m n( ), ,2 ' , (15)

wheream,n are the amplitudes andτ’m,n are the time-delays required to compensate for di�erent arrival times of the signals being received in each element by aligning them in time. �ese time-delays are calculated using the coordinates (xm, ym)of the array elements and dimension-less direction cosines u’ e v’ corresponding to the beam-steer angles θ’ and ψ’ (ZIOMEK, 2016):

τ = +uc

x vc

ym n m n' ' ', (16)

Once cophased and converted to the time domain, the signals can be summed up, resulting in the ³rst output men-tioned above: the beamformed signal, which is basically the reconstruction of the signal emitted by the acoustic source.



| 91 |

�e ³rst method for the estimates θ ψs s( ˆ , ˆ ) of the acoustic source coordinates consists of calculating and plotting the time-average power of the beamformed signal, as the beam-steer angles (θ’, ψ’) are varied. In the case of the simulations performed in this work, the angles θ were kept constant, and only ψ were varied.

�e peak value of the time-average power curve versus ψ ψ=s Pavgˆ ' max indicates the estimate ψ ψ=s Pavg

ˆ ' max .�e second method, detailed in Ziomek (2016), uses the

frequency spectrum of the beamformed signal, R q f x yˆ( , , , ), to calculate the estimate of the frequency-and-angular spec-trum R q r sˆ( , , ).

It consists of a density curve u vs. v vs. magnitude, whose peak, without beamforming — that is, ( ', ') = (0, 0), indicates the dimensionless direction cosines corresponding to θ ψs s( ˆ , ˆ ).

�e frequency-and-angular spectrum is obtained by the two-dimensional spatial DFT of the frequency spec-trum — R q f x yˆ( , , , ), which is calculated by a mathematical expression analogous to the time-domain DFT. However, while in the latter case the transform mapping is carried out in terms of frequency bins, the spatial DFT is mapped in terms of spatial frequency bins, which relates the wave-length of the operating frequency to the coordinates of the planar array’s elements.

First, the spatial DFT of R q f x yˆ( , , , ) in the X direction is cal-culated, resulting in the estimate of the frequency-and-angular

spectrum R q r nˆ( , , ), where r is the bin corresponding to fX (the spatial frequency in the X direction). Next the spatial DFT of R q r nˆ( , , ) in the Y direction is calculated, resulting in the estimate of the frequency-and-angular spectrum R q r sˆ( , , ), where s is the bin corresponding to fY (the spatial frequency in the Y direction). �e estimate R q r sˆ( , , ) is proportional to the twin-line planar array’s beam pattern (ZIOMEK, 2016).

3. RESULTS AND DISCUSSION

The beam pattern of the twin-line planar array, cal-culated for the operating frequency of 1,000 Hz — used to dimension the array’s interelement spacing — showed strong rejection to port-starboard ambiguity, with a single main lobe and very small sidelobes, as shown in Figure 5A. As the operating frequency was reduced, an image of the main lobe stood out from the other sid-elobes until reaching about 70% of the main lobe mag-nitude, at 500 Hz. The other main lobes also had their bandwidth increased, and at 500 Hz two symmetrical lobes were added (Figure 5B).

Next the behavior of the beam pattern (relative to the positive X axis) was tested for the frequency of 1,000 Hz. The beam pattern was practically unchanged up to 15º of beam-steer. Even at 30º, with some distortion in the

A B

Figure 5.Twin-line planar array’s beam pattern: effect of the frequency on ambiguity rejection for the operation frequencies 1.000 Hz (A) and 500 Hz (B).

°

Y

X

90° 75°60°

45°

30°

15°

0°

-90° -75°-60°

-45°

-30°

-15°

105°120°

135°

150°

165°

±180°

-105°-120°

-135°

-150°

-165°

Y

X

90° 75°60°

45°

30°

15°

0°

-90° -75°-60°

-45°

-30°

-15°

105°120°

135°

150°

165°

±180°

-105°-120°

-135°

-150°

-165°



| 92 |

secondary lobes, the beam pattern showed strong rejec-tion to ambiguity, with the main lobe only slightly wider. Further increasing the beam-steer towards the endfire, one could notice some asymmetry and increase of main lobe’s bandwidth, which started to join a group of side-lobes symmetrically distributed around it, relative to the Y axis, as shown in Figure 6.

�ese results worked as an initial reference for the tests of the following step of the research, namely the simula-tions with the signal generator system associated with a twin-line planar array. Two cases were considered in the simulations at 1,000 Hz: the acoustic source placed at ψs = 15º, for whose beam-steer angle ψ’ the beam pattern is practically free of distortion. Afterwards the source was placed at ψs = 55°, corresponding to a beam-steer angle for which the beam pattern shows a strong symmetry, with an image of the main lobe showing approximately 70% of relative magnitude. In the worst signal-to-noise ratio sce-nario tested (i.e., SNR = -3 dB), the resulting estimates were close to the actual values for both cases, as listed in Table 1. Due to these encouraging results an additional simulation was performed for ψs = 65°, resulting in a main lobe image reaching almost 80% of relative magnitude.

4. CONCLUSIONS

�e twin-line planar array resolves the problem of port-star-board ambiguity in the frequency used to dimension its inte-relement spacing, as observed for the operating frequency of 1,000 Hz. By reducing the frequency, the ambiguity rejection is compromised by a progressive increase in symmetry of the beam pattern. At 1,000 Hz, the beam pattern’s beam-steer limit is 55°.

The system composed of the signal generator and the twin-line planar array proved to be an e�ective tool to test the functions for processing a CW acoustic signal using the array. �e e�ectiveness of the array was evaluated by two methods: time-average power and frequency-and-angular spectrum. In both methods, estimates of target position at ψs equal to 15, 55 and 65° approached the expected values. �e system can be optimized to operate with multiple targets, introduction of target movement, programming of a more realistic propagation model, and introduction of a detection module. In order to more accurately and reliably evaluate the results of the simulations, the next step could be applying the Monte Carlo method to statistically test both methods for estimating target location.

5. ACKNOWLEDGEMENTS

This paper was based on my Master’s thesis, accom-plished in June 2016 at the Naval Postgraduate School (NPS), in Monterey. I thank once again the Brazilian Navy for the opportunity of improvement full time in my studies on underwater acoustics and signal processing, and I hope to be able to contribute in the same degree to the research and development of underwater acoustic systems for the defense of the country. I am very grateful to my instructor and advi-sor at NPS, Prof. Lawrence J. Ziomek, to whom I owe a lot in terms of theoretical and practical research knowledge.

ψs

Mean power method

Frequency-angular spectrum method

15 ° 14.9 ° 14.9 °

55 ° 54.9 ° 55.2 °

65 ° 65.3 ° 64.5 °

Table 1. Estimate of the acoustic source’s spherical coordinate ψs.

Figure 6.Twin-line planar array’s beam pattern: steering effect on ambiguity rejection.

Y

X

90° 75°60°

45°

30°

15°

0°

-90° -75°-60°

-45°

-30°

-15°

105°120°

135°

150°

165°

±180°

-105°-120°

-135°

-150°

-165°



| 93 |

CETACEAN RESEARCH TECHNOLOGY. C55 Series Hydrophones.

Disponível em: <http://www.cetaceanresearch.com/hydrophones/

c55-hydrophone/index.html>. Acesso em 14 maio 2016.

KAPOLKA, D. Underwater Acoustics for Naval Applications: notas do

curso PH3452-Underwater Acoustics, Naval Postgraduate School.

Monterey, CA: Naval Postgraduate School, 2015. 90p.

KINSLER, L.E.; FREY, A.R.; COPPENS, A.B.; SANDERS, J.V.

Fundamentals of Acoustics, 4ª ed. Nova York: John Wiley & Sons,

2000. 175p.

REFERENCES

LASKY, M.; DOOLITTLE, R.D.; SIMMONS, B.D.; LEMON, S.G. Recent

Progress in Towed Hydrophone Array Research. IEEE Journal of

Oceanic Engineering, v. 29, n. 2, p. 374-387, 2004.

LURTON, X. An introduction to underwater acoustics: principles and

applications. Chichester, U.K.: Springer/Praxis Publishing, 2002. p. 115-149.

URICK, R.J. Principles of underwater sound. 3ª ed. Westport,

CT: Peninsula Publishing, 1983. p. 332-342.

ZIOMEK, L.J. An introduction to sonar systems engineering. Boca

Raton, FL: CRC Press, 2016.

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