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7/29/2019 DTB0213 http://slidepdf.com/reader/full/dtb0213 1/61 Cov ToC +       ➮ A Intro How to Navigate the Magazines: At the bottom of each page, you will see a navigation bar with the following buttons: Arrows: Click on the right or left facing arrow to turn the page forward or backward. Introduction: Click on this icon to quickly turn to this page. Cover: Click on this icon to quickly turn to the front cover. Table of Contents: Click on this icon to quickly turn to the table of contents. Zoom In: Click on this magnifying glass icon to zoom in on the page. Zoom Out: Click on this magnifying glass icon to zoom out on the page. Find: Click on this icon to search the document. You can also use the standard Acrobat Reader tools to navigate through each magazine. Cov ToC +       ➮ A Intro Welcome to your Digital Edition of Defense Tech Briefs, now featuring  Aerospace Engineering Included in This February 2013 Edition: Defense Tech Briefs Aerospace Engineering Volume7•Number 1•February2013  w ww.d  e  fe  nse  te  c   h   br  ie  fs.  co  m INSIDE: Modeling and Simulation Techniques for Unmanned  Vehicle Systems Trends in Military System Thermal Management Now Featuring Supplementto NASATechBriefs Click Here aero-online.org February2013 Airbus Looks to the Future Aluminum Makes a Comeback Flight Display Trends Top Technologies of 2012 Click Here Intro Cov ToC + A

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Page 1: DTB0213

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AIntro

How to Navigate the Magazines:

At the bottom of each page, you will see a navigation bar with the following buttons:

Arrows: Click on the right or left facing arrow to turn the page forward or backward.

Introduction: Click on this icon to quickly turn to this page.

Cover: Click on this icon to quickly turn to the front cover.

Table of Contents: Click on this icon to quickly turn to the table of contents.

Zoom In: Click on this magnifying glass icon to zoom in on the page.

Zoom Out: Click on this magnifying glass icon to zoom out on the page.

Find: Click on this icon to search the document.

You can also use the standard Acrobat Reader tools to navigate through each magazine.

Cov ToC + – ➭      ➮

AIntro

Welcome to your Digital Edition ofDefense Tech Briefs, now featuring

 Aerospace Engineering

Included in This February 2013 Edition:

Defense Tech Briefs Aerospace Engineering

Volume7•Number 1•February2013

 w w w. d e f

 e n s e t e c  h

  b r i e f s. c

 o m

INSIDE:

Modeling andSimulation Techniquesfor Unmanned Vehicle Systems

Trends in Military System Thermal

Management

Now Featuring 

Supplementto NASATechBriefs 

Click Here

aero-online.org  February2013

Airbus Looksto the Future

Aluminum Makes a Comeback

Flight Display Trends

Top Technologies of 2012

Click Here

Intro

Cov

ToC

+

A

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Volume 7 • Number 1 • February 2013

 w w w. d e f e n s e t

 e c  h  b r i e

 f s. c o m

INSIDE:

Modeling andSimulation Techniquesfor Unmanned Vehicle Systems

Trends in Military System Thermal

Management

Now Featuring 

Supplement to NASA Tech Briefs 

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AIntro

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Free Info at http://info.hotims.com/45600-790

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AIntro

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AIntro

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2 Defense Tech Briefs, February 2013Free Info at http: //info.hotims.com/45600-792

Contents  Vo091*?91'*6?*'69&6=

FEATURES

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21 AEROSPACE ENGINEERING

NEW! Beginning this month, Aerospace Engineering 

becomes part of Defense Tech Briefs as a special

bound-in supplement, bringing together two great

brands and expanding Defense Tech Briefs ’ coverage

of the military and commercial aerospace industries.

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Features

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38 RF & Microwave Technology 

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42 !.190&8.3248.1.>*7!&+*8=&2)*6+361&2(*%-*228*,6&8.2,&228*22&283&0&8+361

TECHNOLOGY FOCUS

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ON THE COVER

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Image courtesy of Abbott Technologies 

aero-onl i ne.org  February 2013

Airbus Looksto the Future

AluminumMakesaComeback

FlightDisplayTrends

TopTechnologiesof2012

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AIntro

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There is no shortage of challengesfacing thermal engineers intoday’s military and aerospace

applications, from the inherent prob-lems caused by harsh environments tothe challenges created by advances inelectronics and other technologies. Andmilitary specifications are continually upping the ante when it comes to per-formance, footprint and weight.

Thermal devices for today’s military sys-tem must be small and compact, due tostringent weight and space/volume con-

straints, as in fighter aircraft, where every ounce and each cubic inch can impact 

performance. Thermal solutions must also be able to reject heat efficiently, even

 where packaging volumes are limited andcannot be expanded, as in satellite appli-cations. Maintenance needs must be kept to a minimum because repairs may be dif-ficult in the field or at sea (e.g., subma-rine electronics cooling systems), or evenimpossible in certain aerospace applica-tions such as satellites. Military systemsmust operate under conditions far moredemanding than most civilian applica-tions, from radar transmit-receive mod-

ules functioning in oppressive desert ortropical heat, to satellite and aerospace

systems that deal with both electronics-generated heat and intense ambient cold.

 Yet mission-critical reliability is a must inall cases, whether conditions allow tradi-tional maintenance or not. Finally, ther-mal engineers are being asked to helpelectronics designers meet the strict size,

 weight and power (SWaP) requirementsset forth in today’s military specifications.

Thermal engineers working with mili-tary systems must also deal with thesame challenge that all thermal engi-neers have faced in the past few 

decades, namely increased heat gener-ated by advanced and increasingly miniaturized electronics in spaces that are continually becoming smaller.Thermal engineers have developed anumber of creative approaches to deal

 with these challenges, but all have theirdrawbacks. Traditionally, designers havefavored passive heat transfer devices likeheat sinks or heat pipes, generally madefrom aluminum or copper. These ther-mal devices offer the advantage of hav-ing no moving parts to fail, reducingmaintenance needs to a minimum. But aluminum has limited conductivity,

 which has a greater impact as electron-ics become more powerful, and copperis relatively heavy (three times as heavy as aluminum).

However, there is one promising ther-mal management approach that avoidsthese problems. It involves the use of annealed pyrolytic graphite, or APG,encapsulated within a structural shellmade from traditional materials such asaluminum, copper, beryllium, ceramicsor composites. Encapsulated APG was

first used operationally in high-flyingDoD aircraft, where its lightweight char-acteristics earned it early acceptance inapplications where each pound savedcould be transformed into anotherpound of fuel or additional avionics.The low mass of encapsulated APG-based solutions is still a key factor in reli-able cooling solutions for remote elec-tronics and navigational avionics.

But encapsulated APG offers addition-al thermal advantages that go beyondlight weight, and apply to many military 

systems. The most fundamental advan-tage is high conductivity at low mass.

4  www.defensetechbriefs.com Defense Tech Briefs, February 2013

Trends in Military SystemThermal Management

Figure 1. The encapsulated APG material has three times the conductivity of copper with a massdensity less than that of aluminum. The APG insert provides a high k path while the encapsulatingshell sets the CTE and structural properties. Thermal vias may be used to increase the conductanceinto the APG.

Table 1. Common electronic packaging materials. The relatively high specific conductivity of alu-

minum, combined with its affordability, explains its wide use as a heat sinnk material for space andairborne applications.

Termal Density Coef of Thermal Specific ConductivityMaterial Conductivity (g/cm3) Expansion (conductivity/density.

(W/mK) (ppm/K) W/mK/g/cm3)

Copper (OFHC) 390.0 8.90 16.9 43.8

Beryllium 220.0 1.80 13.5 122.2

Alluminum Beryllium (62% Be) 210.0 2.10 13.9 100.0

Alluminum (6061) 180.0 2.80 23.6 64.3

Alsi (40% Si) 126.0 2.53 15.0 49.8

Magnisium (AZM) 79.0 1.80 27.3 43.9

Kovar 14.0 8.40 5.9 1.7

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Defense Tech Briefs, February 2013 5

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Encapsulated APG material offers threetimes the conductivity (k) of copper witha mass less than aluminum. This resultsin a significant improvement in conduc-tivity for any encapsulant paired with

 APG. Encapsulated APG’s high conduc-tivity, combined with its low mass densi-ty, results in a material system with out-standing performance per pound, or

specific conductivity (W/m·K/g/cm3).The specific conductivity of encapsulat-ed APG materials range from 4- to 10-times that of traditional thermal man-agement materials. For example a cop-per encapsulated APG heatsink with an80% APG volume fraction would haveapproximately eight times the specificconductivity of copper alone.

 Another benefit of encapsulated APGis that the coefficient of thermal expan-sion (CTE) offered by this solution canbe tailored to specific application needs

by altering the choice or configurationof the encapsulant. CTE can also bematched to a specific application, allow-ing dissipation of dramatically increasedheat fluxes by permitting direct attach-ment, thereby minimizing thermalresistance. By combining the high ther-mal conductivity of APG with an easily-tailored CTE encapsulation material,

engineers can create solutions for high-powered military electronics while keep-ing weight and footprint under control.Designers can choose the encapsulant 

that most closely matches the CTE of electronic materials such as silicon andgallium arsenide, allowing the direct attachment of these devices and provid-

Figure 2. The placement of a thermal via will improve the through-the-thickness conductivity to that of the encapsulation material.

Table 2. Encapsulated APG components with common electronic packaging materials as the encap-sulating shell. The calculated values are for the in-plane heat flow with a 60 percent volume fractionof the APG insert.

Termal Density Coef of Thermal Specific ConductivityMaterial Conductivity (g/cm3) Expansion (conductivity/density.

(W/mK) (ppm/K) W/mK/g/cm3)

Copper (OFHC) w/APG insert 1176.0 4.92 16.9 239.2

Beryllium w/APG insert 1108.0 2.08 13.5 533.7

Alluminum Beryllium (62% Be) 1104.0 2.20 13.9 502.7w/APG insert

Alluminum (6061) w/APG insert 1092.0 2.48 23.6 441.0

Alsi (40% Si) w/APG insert 1070.4 2.37 15.0 452.0

Magnisium (AZM) w/APG insert 1051.6 2.08 27.3 506.6

Kovar w/APG insert 1025.6 4.72 5.9 217.5

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ing the thermal benefits of both APGand the encapsulation material.

Encapsulated APG also offers simpleintegration into current and planned

systems. Because the APG is hermetical-ly sealed within the encapsulating mate-rial, it is compatible with standard finish-ing and processing manufacturing stepsas well as with the encapsulation materi-als themselves. These encapsulated APGsolutions, with no moving parts, givethermal engineers greater design flexi-bility, more durability, and less mainte-nance concerns.

 All of these advantages make encapsu-lated APG an ideal material for military applications, enabling the technology 

that satisfies today’s needs for high-den-sity packing requirements in a limited

space. Thermal technologies based onencapsulated APG have proven to per-form well under demanding tempera-ture, stress, load, vibration and other

conditions as protection for avionics, tar-get acquisition, imaging and other sys-tems in mission-critical applications on-board fighter aircraft (such as the F-16,F-22 and F-35 Joint Strike Fighter) andhelicopters. Encapsulated APG-basedsolutions help sensitive electronics con-tinue to function in temperatures downto -70° C and in 9g load conditions.

 Another critical and popular use of encapsulated APG is in outer space.Here, where maintenance is obviously impossible, encapsulated APG-based

radiator panels, thermal doublers,brackets, and circuit card heat sinks pro-

 vide lightweight, high-performance heat management in the harshest of environ-ments, keeping irreplaceable electroniccomponents online. The reliable con-ductivity of encapsulated APG is particu-larly valuable in these applicationsbecause the thermal area for rejectingheat cannot be increased.

In addition, encapsulated APG-based

technology has proven successful inmeeting one of the strictest require-ments in military systems design – reduce

 weight and footprint to a minimum somore weight and space can be devoted toother system elements. At the same time,

 APG delivers the performance that coolseven the most powerful electronic com-ponents and next-generation compo-nents, allowing designers to focus less onthermal management and more on coretechnology. For example, encapsulated

 APG lets system designers pack in more

powerful electronics and more compo-nents in tighter spaces. Electronic com-ponents can also be made much smaller,both because APG-based solutions canhandle the resulting increased heat, andbecause the APG-based solutions aresmaller in themselves.

The properties of encapsulated APG,at work in so many military applicationstoday, are also opening up new possibili-ties for the future. One example is flexi-ble thermal links for aircraft, integrating

 APG with a flexible heat pipe to cool tar-get acquisition sensors while isolatingthem from the aircraft’s vibration. Theflexibility of APG and the strength of theencapsulation material combine to pro-

 vide a thermal solution with mission-crit-ical reliability.

In conclusion, encapsulated APG offerssignificant application-based ad vantagesfor thermal engineers that outweigh thehigher initial cost. APG is relatively easy toencapsulate, manipulate and finish. It iscompatible with a wide range of encapsu-lation materials and standard manufactur-ing steps, and offers the opportunity to

CTE-match encapsulants with electronicmaterials. The resulting design flexibility can lead to more effective, reliable mili-tary electronic systems, with a greaterrange of applications. Finally, thermalengineers are still exploring the potentialof this thermal technology, and are devel-oping new solutions that will make encap-sulated APG even more valuable and

 widely used in future military systems.This article was written by Mark J.

Montesano, VP of Engineering and Tech - nology, Thermacore, k Technology Division 

(Langhorne, PA). For more information, visit http://info.hotims.com/45600-501

6  www.defensetechbriefs.com Defense Tech Briefs, February 2013

Thermal Management

Figure 3. Aluminum encapsulated APG powersupply chassis for an airborne electronics appli-cation. The conductance of this k-Core chassiswas nearly four times higher and had an 11%lower mass than the baseline aluminum part of

 the same geometry.

Figure 4. These thermal scans of two power supplies dissipating the same power and having thesame geometry illustrate the benefit of high conductance. The k-Core supply chassis’ high conduc-

 tance results in a significant temperature reduction over the baseline aluminum design.

Aluminum Baseline

Max Surface Temperature - 61.3°C

Aluminum Baseline

Max Surface Temperature - 61.3°C

k-Core® Material

Max Surface Temperature - 22.8°C

k-Core® Material

Max Surface Temperature - 22.8°C

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8  www.defensetechbriefs.com Defense Tech Briefs, February 2013

Unmanned Autonomous Vehicle(UAV) systems have become pos-sible in recent history thanks pri-

marily to the effects of Moore’s Law —the doubling of processing power every 18 months. This trend, coupled withimprovements in sensors and actuators,has enabled the advanced signal anddata processing necessary to controlUAVs. However, the complexity of UAV systems has taxed traditional design

 workflows, and revealed numerous chal-lenges such as shorter design cycles,greater performance and reliability demands, and cost constraints.

 As a consequence of these stresses onthe traditional component-centricdesign process, the engineering commu-nity has turned to Model-BasedDevelopment (MBD) to help accelerateand manage the development process.MBD processes rely on software modelsto move as much of the design process

onto software as possible, with an eye onreducing the number of physical proto-types, achieving optimal performance,and improving system reliability.Ultimately, the MBD process aims to get better products to market faster, thussaving time and increasing profits.

Figure 1 shows a high-level view of anMBD process, typically called a V-dia-gram. On the whole, the process begins

 with requirements and ends with testingthe actual product. In other words, it begins with modeling and design, and

ends with testing and validation and ver-ification (V&V).

Though this modeling paradigm hasbeen in place for at least the last decadeor more, there is a recent push for sys-tem-level models for the purpose of Concept Design. Models for Concept Design play three roles:

1. To confirm that requirements aremet (connection to Requirementsand Specifications);

2. To generate meaningful topologiesand bounds on parameters to the

 virtual prototyping tools (connec-tion to Detailed Design); and

3. To provide fast and accurate mod-els for “x”-in-the-Loop Simulation(xILS) (connection to System Test).

System-Level RequirementsNeed System-Level Models

Requirements originate from the mar-kets for which a product is beingdesigned. They are a statement of crite-ria that must be satisfied for a product to

be successful. In the case of UAVs, “TheUAV must never crash,” or “The UAV must have a range of 100km,” would beexamples of system-level requirements.The results of these requirements arespecifications that serve as benchmarksto guide the detailed design of compo-nents and subsystems. For example, thelatter requirement might necessitate aspecification for a particular minimumfuel capacity and maximum UAV mass.

In the past, the focus has been oncomponent- and subsystem-level model-

ing and design, relying on the develop-ers of the numerous specifications to

ensure that no problems would occuronce the complete system was integrat-ed. Generally speaking, software solu-tions exist to alleviate problems within asingle domain: CAD packages look formechanical stack-up problems, EDA tools can handle massively complex cir-cuit layouts and predict manufacturingdefects, and numerous other verticalsolutions exist for application domainslike hydraulics, thermal, etc.

However, predicting and mitigatingnegative interactions between thesedomains has been pernicious. Theseinteractions are either expected orunexpected. Modeling the expectedcoupling between domains has beenaccomplished either manually or ingreat detail at the component level. Forexample, consider a servo driver circuit 

 with MOSFETs connected to a heat sink. A design engineer may ask the question,“How does the temperature of the

MOSFETs relate to the heat they aregenerating?” The answer to this ques-tion depends on a variety of electrical,thermal, and fluid properties. Modelingthis interaction would typically require alightweight low-fidelity hand-derivedsolution using lumped parameters (e.g.“The heat capacity of the heat sink isX°C/J”) and governing physical equa-tions, or a heavyweight high-fidelity 3-Dsimulation solution, like COMSOL orNASTRAN. Unexpected interactions aretypically left unexposed until physical

prototypes are created. A more idealtool would capture the physics across

Modeling and Simulation

Techniques for Unmanned

Vehicle Systems

An MQ-1 Predator Unmanned Aerial Vehicle (U.S. Air Force Photo by Tech.Sgt. Erik Gudmundson)

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multiple domains, strike a balancebetween fidelity and speed, and predict the dynamics of complete systems.

 While this is very attractive in theory, without the right tools it is very difficult to achieve in practice. However, new sys-tem-level modeling tools have sought tocapture the complete dynamic behaviorof a system including all of its physical

domains. In the high-performance worldof UAVs, the design engineer from theprevious example could now ask a moremeaningful question based on the sys-tem-level requirements and on thedynamic interaction of the various sub-systems: “Will my necessary yaw rate stillbe possible as my MOSFETs heat up?”

 An additional benefit of a system-levelmodel is its tendency to expose unwant-ed interactions between subsystems. Forexample, resonances between domains(like a rotational resonance coupling

 with a magnetic field resonance), andunintended positive feedback loops(runaway heat generation) can bedetected and mitigated early on.

 At Maplesoft, we have developed sucha system-level modeling and simulationplatform, called MapleSim. Built to takeadvantage of symbolic technology,MapleSim allows complex multidomainsystems to be modeled quickly, and thengenerates the governing dynamic equa-tions for the system. This uniqueapproach produces highly concise rep-resentations of the system model that are fully parameterized for furtheranalysis and optimization, either in thetool’s integrated analysis environment,Maple, or in third-party tools. Moreover,MapleSim automatically generates

 ANSI-C code from the model that isextremely efficient, allowing levels of detail to be implemented in real-timethat are not possible with other tools.

MapleSim is used in a wide variety of industries and projects, including thedesign of UAV systems. For example,Quanser Inc., manufacturers of robotic

and mechatronic systems includinghigh-quality haptic devices, usedMapleSim to develop the QBall, aquadrotor helicopter. With MapleSim,they were able to fully capture thedynamics of the gyroscopic effects,something that is extremely difficult orimpossible to treat with traditional toolsas developing the necessary high-fidelity 

models by hand is difficult and time con-suming. Not only did they achieve ahigh-fidelity model in very little time,but they were also able to uncoverbehaviors in the system they had not taken into account. Quanser engineers

 were able to efficiently evaluate different configurations in the software beforesettling on the final design.

What Does the Future Hold?Historically, the simulation and analy-

sis part of the design process has been a

separate activity from the core designactivities performed with CAD tools, but increasingly these two processes aremerging into a more integrated designprocess. Sometimes called Model-BasedSystems Engineering (MBSE), thisapproach sees the dynamic simulation of the whole system at the Concept Designphase of the design process, but takesthis a step further. It would be possibleto store the functional behavior of sub-systems and assemblies as dynamic mod-els in a database with all the other prod-uct information, such as physical attrib-utes and operational constraints. Theinitial design steps could then be auto-mated — the design team simply entersthe product requirements and the sys-tem offers up some candidate configura-tions that would fulfill, or almost fulfill,those requirements.

MBSE and Configuration Management (CM) are two areas of research that aim tomake the above a reality. From Maplesoft’sperspective, there are several areas of development that we consider to be criti-cal to the success of this activity:

Defense Tech Briefs, February 2013  www.defensetechbriefs.com

23435 Industrial Park Drive

Farmington Hills, MI 48335P: 800.521.3320 / F: 248.476.2470

e-mail: [email protected]

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Figure 1. A high-level Model-Based Development V-diagram.

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10  www.defensetechbriefs.com Defense Tech Briefs, February 2013

1) A rich, consistent, multidomainmodel description language that allows all dynamic behaviors to becharacterized for systems that con-tain many engineering domains,such as electrical, mechanical,hydraulic, pneumatic and thermal.

 While there have been severalattempts at this over the years, one

language - Modelica - is emerging asthe de facto standard. Developed by a consortium of universities andindustrial partners, Modelica hasbeen widely adopted in Europe andis seeing increasing adoption inNorth America and Asia. MapleSimis the first commercially availableModelica tool to be developed inNorth America and Maplesoft isactive in ensuring Modelica fulfillsthe requirements of system-levelengineering within its customer base.

2) Tight integration between many analysis tools. MapleSim isdescribed as a 1-D (i.e., time-domain) lumped-parameter simula-tion tool. This allows for rapidmodel development and simulationexecution and provides goodinsight into a system’s overall func-tional behavior. However, it is oftennecessary to include more complexelements from, for example, finiteelement (FE) or computationalfluid dynamics (CFD) tools. Toachieve this, there is a growingdemand on a standard frameworkthat would allow this level of inter-action between tools. The MOD-ELISAR project, initiated by theModelica Association, has beeninstrumental in defining such aframework. Called the FunctionalMock-up Interface (FMI), it pro-

 vides the ability for tools to interact.3) Integration with CAD tools. At 

some stage in the design process, it is necessary to either extract physi-cal design parameters from a CAD

design or submit optimized designparameters into it. Maplesoft hasdeveloped interfaces with variousCAD tools and these are being fur-ther developed to achieve this goal.

4) Integration with all other opera-tional information. To make CM areality, it is necessary to include alloperational information with thefunctional behaviors of a compo-nent or system model: envelopes of operation, failure modes, environ-mental factors, even manufactur-

ing processes and costs, all need tobe considered. This is an area of 

 very active research, much of it driven by the demands of military 

 vehicle manufacturers. At the coreof this research is the Object 

Management Group (OMG) andthe International Council onSystems Engineering (INCOSE),out of which extensions to theModelica language are being devel-oped using SysML.

MBSE is in its infancy but is rapidly turning into a reality, and manufacturersneed to factor this into their product development and business strategies forthe future. Ultimately, MBSE holds thepromise of dramatically reducing devel-opment effort in multidomain engineer-

ing products, reducing risk of designflaws and getting to market faster.

Early System-LevelModeling is the Key

In summary, the overarching key toeffective MBD is that complex products,

like UAVs, need to be considered as whole systems in order to understandhow the multitude of subsystems interact 

 with each other over the entire range of duties. This needs to be done very early in the design stage so that as the designevolves, the functional behavior can be

 validated throughout the process, thusensuring it continues to fulfill the designgoals of the product.

This article was written by Derek Wright,Product Manager, Maplesoft (Waterloo, ON,Canada). For more information, visit http:// 

info.hotims.com/45600-500 .

Figure 2. To design this quadrotor helicopter, MapleSim was used to develop high-fidelity 3-D dynam-ics models of the system and its flying characteristics.

Figure 3. MapleSim 6 provides enhanced support for Modelica, the open-standard modeling lan-guage for describing physical models.

Modeling and Simulation Techniques

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12  www.defensetechbriefs.com Defense Tech Briefs, February 2013

APPLICATION BRIEFS

Laser Polarimeter ClassifiesRemote Material

 Advanced Optical Technologies Albuquerque, NM505-250-9586www.advanced-optical.com

 Advanced Optical Technologies, Inc. (AOT) has beenawarded a Phase 2 SBIR contract to develop a next-generationlaser polarimeter for the US Army RDECOM CERDEC Night 

 Vision and Electronic Sensors Directorate (NVESD), tradition-ally known as the US Army Night-Vision Labs. The polarimeter

 will implement AOT’s polarization-components techniques(PCT), which apply machine-learning algorithms to polarime-

ter data for remote material classification.Compared to passive polarimeters, which have already been

fielded, active laser polarimeters provide additional informa-tion and enhanced capabilities for automated target recogni-

tion, real-time structural-health monitoring, thin-film, textile,

polymer process monitoring, and debris mapping and assess-ment. AOT expects to have a prototype laser polarimet er ready for NVESD field tests by mid-2014.

For Free Info Visit http://info.hotims.com/45600-507 

Buoy System Tracks Ships in Real Time

Buoy SystemIntellicheck MobilisaPort Townsend, WA888-9ICMOBILwww.icmobil.com

 According to the U.S. Department of Homeland Security,the nation’s 360 ports and waterways remain especially vulner-able to attack from small vessels carrying improvised explosivedevices, including radioactive dirty bombs. IntellicheckMobilisa, a wireless-technology firm, will address the vulnera-bility with Aegeus, a buoy system that communicates in realtime to the shore.

 Aegeus is a constellation of high-tech sensor buoys config-ured with latest-generation wireless communications. Thebuoys operate autonomously, track ships, and detect objects inair, water, or underwater within a range of 17.5 miles.Equipped with advanced environmental and security system

sensors, the buoys share data and network buoy-to-buoy, buoy-to-shore, and at-sea platforms. The buoy sensors includeday/night video, acoustic modem, environmental, oil sensing,radiation hazard detection, and advanced homeland security sensors to extend the protection zone around harbors, ports,and seaways.

Currently there are multiple test buoys, deployed by the U.S.Navy, in the Potomac River and in the Puget Sound region.Two basic configurations have been deployed; one is a security configuration and the other is an environmental/video surveil-lance configuration.

In conjunction with the Aegeus deployment, a complex net- work architecture has been developed to fuse and assimilate

collected data. The arrangement includes a Web-based portalaccessible by a Network Operations Center (NOC) to a secure

database. The network incorporates shore-based equipment, which features radars and long-range pan tilt zoom (PTZ)day/night cameras with the Aegeus buoy system. In concert,the systems present crucial information gained in the field andprovide the ability to analyze and respond accordingly.

The surface security buoys, modular in construction,house an array of sensors, which transmit to shore using

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Defense Tech Briefs, February 2013 13Free Info at http: //info.hotims.com/45600-797

Intellicheck Mobilisa’s Wireless Over Water™ (WOW) tech-nology and other telemetry systems. Installed sensorsinclude: radiation hazard (RADHAZ) detection; day, ther-mal, and low-level light cameras providing streaming video;

 weather station; global positioning system (GPS); digitalcompass; radio; cell; and a maintenance-free power genera-tion subsystem that capitalizes on solar energy for recharg-ing the battery bank.

The buoys are designed to be configurable and adaptable to

 varying mission requirements. A single buoy, for example, canbe assembled as a port security buoy and then modified lateras a communications link, an oil spill detection buoy, or a com-bination of each.

The environmental/video surveillance buoys include a weather station, environmental sonde, GPS, PTZ day/Low Level Light camera, digital compass, cell and radio subsystem,as well as a more robust “hybrid” power system that combines

 wind and solar generation. The Oil Sensing configurationspots surface oil contamination, and the preferred sensordetects refined or crude oil products. With the onboard windand current direction/speed sensors, an alert can be sent to aNOC, and prediction of speed and direction of plume drift can

be made. By receiving the indicator miles out in a channel orto sea, authorities may be notified and halt a ship’s entry intoterritorial waters.

For Free Info Visit http://info.hotims.com/45600-508 

New Technology Could Improve InertialGuidance System Accuracy 

Fast Light Optical GyroscopesMarshall Space Flight CenterHuntsville, AL

256-544-0034www.nasa.gov/centers/marshall

NASA has tapped a team of aerospace, military and academ-ic researchers for a three-year project that could dramatically improve in-flight navigation capabilities for space vehicles, mil-itary air and sea assets, and commercial vehicles. The project,“Fast Light Optical Gyroscopes for Precision InertialNavigation,” is intended to enhance the performance of a vehi-

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cle’s inertial guidance system by refiningthe optical gyroscopes that drive it.These highly sensitive gyroscopes,paired with accelerometers, measure a

 vehicle’s attitude or orientation basedon its angular or rotational momentumin flight, and track its velocity and accel-eration to precisely determine its posi-tion, flight path and attitude.

Gyroscope-based inertial guidancesystems are nothing new; Americanrocketry pioneer Robert Goddarddeveloped elementary gyroscopes forhis launch tests in the early 1900s. The

technology later was adapted to serve arange of high-tech spacecraft, guidedmissiles and commercial aviation. But researchers supporting the new project say their sophisticated new opticalgyroscopes could be at least 1,000times more sensitive than current gyro-scopes – even in this initial prototypedemonstration. That’s a critical leap

forward as the nation plans new robot-ic and crewed missions into the solarsystem. Even the best modern space-flight navigation systems can sufferfrom accumulated “dead reckoning”

errors – positioning miscalculationsthat result when an absolute point of reference, or a fixed “landmark” inspace, is not readily available. To cor-rect for such errors, flight operationspersonnel must rely on backup tech-nologies, including Earth-based sys-tems such as a global positioning sys-tem, or GPS. But such measures often

lack the precision or uninterruptedflow of data needed to make criticalcourse adjustments or maneuvers.

Enter the Fast Light OpticalGyroscope project team, who are investi-gating the use of optical dispersion, orthe manner in which different wave-lengths, or “colors,” of light travel at dif-ferent speeds through a material, tomanipulate the sensitivity of the gyro-scopes’ optical cavities. In certain mate-rials, such as the atomic gases the team isstudying, this dispersion can cause puls-

es of light to travel faster than the speedof light in vacuum. This phenomenon,known as “fast-light,” can increase thesensitivity of a gyro’s optical cavity, allow-ing it to more precisely measure how fast a spacecraft is rotating – the crux of accurate and reliable inertial navigationdata.

The team anticipates initial laboratory demonstration of the new gyroscopes by early 2014, with field tests in 2015.

For Free Info Visit http://info.hotims.com/ 45600-540 

14 Defense Tech Briefs, February 2013

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APPLICATION BRIEFS

Game-Based Training Applications Teach SoldiersCultural Skills

 Virtual Training EnvironmentsCharles River AnalyticsCambridge, MA617-491-3474www.cra.com

Charles River Analytics released a case

study of an effort for the US Army calledCAATE (Culturally Aware Agents forTraining Environments). Under thiseffort, Charles River developed tools tocreate game-based training applicationsfor soldiers that teach them mission-crit-ical social and cultural skills. Throughcomputer games and by interacting withCAATE-based artificially intelligent agents, soldiers can safely train to effec-tively interact with residents of othercountries and from different cultures.

The problem is today’s warfighters are

increasingly engaging in peacekeepingmissions, humanitarian missions, and

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Defense Tech Briefs, February 2013 15

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stability and support operations. These missions often require junior leaders and soldiers to interact and communicate effec-tively with people whose cultures, languages, lifestyles, andbeliefs are very different from those found in the US.

Computer-based training in virtual environments has thepotential to train soldiers to rehearse missions with a sound

knowledge of the relevant local culturalcontext. Existing computer simulationsof culturally situated agents represent-ing humans are either very limited infidelity, making them unsuitable fortraining and rehearsal, or prohibitively expensive to develop and maintain asmissions and needed skills change.

Under the CAATE effort, Charles

River designed and prototyped a mod-eling toolkit called Persona™ fordesigning computer-controlled agentsfor cultural training applications. Theapproach uses graphical social networkmodeling technologies to develop mod-els of socially interconnected agentsand a graphical human behavior mod-eling tool for creating culturally-appro-priate behaviors for the simulatedagents.

Charles River also developed ademonstration training application that 

uses socially dynamic agents in a virtualenvironment to teach simple social

skills. One of the advantages of Persona is that it makes it easy,using a single user-facing tool, to create agents for several differ-ent virtual environments. So far Persona has been used to cre-ate virtual agents for a variety of simulation environments,including VBS2, OLIVE, and Half-Life 2.

For Free Info Visit http://info.hotims.com/45600-539 

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16 Defense Tech Briefs, February 2013Free Info at http: //info.hotims.com/45600-800

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APPLICATION BRIEFS

Smart Hoses Simplify Unmanned Aircraft Refueling

Hose SystemIcon Polymer GroupRetford, Nottinghamshire, UK +44-1777-714-300www.iconpolymer.com

Icon Aerospace supplies refueling hoses to Tier-1 suppliersand air forces across the globe. The IconIC™ hose systemsecures power with telemetry cables and fiber-optics for datatransfer. The technology provides a range of key control and

communication functions to take place between a tanker andreceiver aircraft while the receiver aircraft undergoes mid-airrefueling.

The new system enables precise, remote positional controlof the refueling hose, particularly appropriate as the use of unmanned combat air vehicles (UCAVs) and autonomousunmanned aerial vehicles (AUAVs) continues to grow. Theintegration of the data transfer capability allows for diagnos-tics and reprogramming. An embedded termination collar

connects into a “clamshell” user-defined interface, switch-able in flight, into which a variety of functions can be inte-grated depending on user requirements.

For Free Info Visit http://info.hotims.com/45600-509 

Refueling system basket locator. IconIC hose system’s embedded termination collar.

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Defense Tech Briefs, February 2013  www.defensetechbriefs.com 17

T

here are power supplies in virtually every military electronic system.

These ubiquitous devices come inall sizes and power ratings. And just liketheir commercial counterparts, they areavailable in the AC/DC, DC/DC andDC/AC configurations that provide theappropriate electrical energy to operatethe electronics.

For years, the difference between amilitary power supply and its commercialcousin has been reliability. This is prima-rily because a loss of power in a military system is not only inconvenient, it couldresult in a catastrophic failure andunnecessary loss of life. Military powersupplies were designed with long MTBF(mean time between failure) ratings inmind, with a goal of delivering years of trouble-free operation.

Today, as in the past, reliability of mil-itary supplies remains paramount withMTBFs exceeding those of commercialcounterparts, but now military systemsare also being upgraded every two years

 just like consumer electronics. Witheach upgrade, the previous generationof power supplies becomes obsolete, soobsolescence and availability issues

have become more likely, while oldideas of standards-based and system-certified supplies make less sense. Inaddition, the ability to recognize apending failure is becoming as impor-tant as long-term reliability.

The same trends that forced military users to adopt COTS standards for most computer equipment (e.g., rapid tech-nology advances, component obsoles-cence, etc.) now apply to the power con-

 version industry. Nevertheless, there arestill specific requirements that manufac-

turers of military power supplies must meet. These include detailed guidelines

for selecting components that are part of each supply, a rigorous set of design rulesto ensure manufacturability, and many specifications focused on the environ-ment in which the supply will be used.

Parts Selection and DesignParts selection is an important step in

designing a military power supply and isclearly detailed in the U.S. Navy’s SD-18“Parts Requirements and Application 

Guide .” All components used in theproducts must be qualified either by their manufacturer for use in military systems, or qualified for the applicationby the manufacturer of the power sup-ply. This process is meant to accomplishtwo things. The first is to establish that astable source of supply for the compo-nent exists and adequate quality controlprocedures are in place. The second isto prevent the usage of restricted mate-rials that can degrade during normalusage. SD-18 also governs rules for der-

ating components to help designersmeet challenging specifications with

more common commercial grade com-ponents.

 While long life cycles may be a thingof the past, there remains a requirement that military electronics systems must bereplaceable or at least repairablethroughout their lifetime. This canplace added demands on the military power supply manufacturer. For exam-ple, if a part used within a power supply is being discontinued by a component 

manufacturer, and an equivalent quali-fied part is not available from anothersource, the power supply maker must notify all previous buyers of the supply and offer a final build plan to allow them to order spares for future usage.

 When it comes to design of military power supplies, NAVSO P3641 is the pre-mier reference. First introduced in 1999,this comprehensive set of guidelines,subtitled “More Power for the Dollar,” details the best manufacturing practicesfor military power supplies. It includes

provisions allowing the use of COTS(commercial-off-the-shelf) power sup-

LookingUnder theHood of aMilitaryPowerSupply

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plies in applications like telecommunica-tions, computing, or air traffic control

 where benign conditions do not exceed0° to 70 C° limits. It also details require-ments for designing and building powersupplies for the more rugged -40° to +85°C conditions encountered in the field.

These guidelines suggest the use of metal clad printed circuit boards, surface

mount packages for integrated circuits,gold plated interconnects to reduce theeffects of corrosion, physical designparameters that impact cooling, electro-magnetic interference management techniques including shielding and phys-ical layout, and many more designdetails. It also gives detailed designguides for high and low voltage DC/DCconverters, as well as AC/DC supplies,inverters and uninterruptable power sup-plies. In addition, environmental stressscreening parameters and procedures,

including highly accelerated stressscreening and testing, are outlined.

 Application Requirements Various branches of the military have

published detailed sets of requirementsthat establish what will be expected of power supplies from all types of military systems deployed in the field. TheseMilitary Standards — or MIL-STDs —focus on performance issues as well asenvironmental conditions that canimpact reliability.

Input voltage conditions for tacticalmilitary applications cover electromag-netic compatibility and input levels. Theformer is spelled out in MIL-STD-461

 which details the amount of conductedRF energy the device must be able to

 withstand and still operate properly.This is typically 40 dB or more of attenu-ation from the internal power supply switching frequencies all the way out toseveral megahertz. Commercially avail-able filters that meet FCC requirementsfor commercial noise suppression can-not achieve this level of signal rejection.

So each military power supply applica-tion must be approached individually toconstruct filters and maintain properimpedance matching characteristics toeliminate radiated noise at the input.

Meeting the full range of input volt-ages required for military applicationscould be a challenge for off-the-shelf commercial products. For example MIL-STDs generally detail three input volt-age ranges for each device. The first 

 would be normal operation; the second“abnormal” like when a malfunction or

failure has occurred and protectiondevices are functioning to correct the sit-

18 Defense Tech Briefs, February 2013Free Info at http://info.hotims.com/45600-801

Abbott Technologies AM200 military power sup-ply with 200 watt output, enhanced EMI, and100% condensing option.

Abbott Technologies CM500 military power sup-ply with 500 watt output, fully sealed to meetIP65, and 28 VDC output voltage.

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Defense Tech Briefs, February 2013 19

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uation; the third is emergency where themain generating equipment has failedand a limited independent source ispowering vital systems. Examples for air-craft and vehicular standards are shownin the accompanying table.

Note that in all cases the minimumaccepted input is lower for military power supplies than is generally found

in specifications for COTS devices. Thismeans that COTS supplies would shut down at higher voltages while military grade devices keep on powering systems.This is primarily because designers of military compliant devices tend to opti-mize performance of their DC/DCdesigns by trading off maximum output current for a wider input voltage range.High line ratings present another prob-lem for COTS DC/DC converters, sincetheir maximum rated line capability isless than applicable MIL-STDs. Here

military compliant modules utilize clip-ping and pre-regulation schemes to pre-

 vent damage and allow for reliable oper-ation across the entire full voltage range.

Harmonic noise and distortion can alsobe an issue with most commercial powersupplies in certain environments. Forexample, in shipboard applications, MIL-STD-1399 specifies that single harmonic

distortion be limited to 3 percent and totalharmonic distortion to below 5 percent.Commercial units would require large pas-sive components to meet these levels,

 whereas military designers accommodatethese conditions as a matter of course.

Transient protection is required for vir-tually all military power supply input stagesand varies from application to application.

 A typical specification can be found in theMIL-STD-1275B requirements for military 

 vehicles. Here the input for a 28VDCDC/DC converter must be able to survivea spike of up to ±250V that is 50 μsec widein a burst of 1 msec duration with 15 mJmaximum energy content per spike.Surges of up to 100V for 50 msec from a0.5 Ohm source impedance repeated 5times per second must also be accommo-dated. Most commercial units can meet 

neither specification, but well designedmilitary units can. In addition military units must often be designed to survivelightning strikes and this would increasespike and surge protection requirementsby several orders of magnitude.

Environmental Challenges While some commercial power sup-

plies might encounter some tough oper-ating environments on the factory floor

or out in the weather, for example, mili-tary power supplies must operate reliably in a wide range of environments fromdeep space to undersea, from deserts toswamps and from the tropics to the arctic.

 As a result, a complete set of MIL-STDshave been developed to provide guide-lines for the design and testing of units toaccommodate any operational mission.

Condition Aircraft power Vehicle PowerMIL-STD-704A MIL-STD 1275

Normal 25 to 28.5 VDC 25 to 30 VDC

Abnormal 23.5 to 30 VDC 23 to 33 VDC

Emergency 17 to 24 VDC 20 to 27 VDC

Selected input voltage ranges for power supplies used in aircraft and land vehicles.

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20  www.defensetechbriefs.com Defense Tech Briefs, February 2013

Extended temperature range : Commercialpower supplies are generally de veloped

 with an operating temperature range of 0°to +70° C in mind. At a minimum, military power supplies must accommodate tem-peratures from -40° to + 85° C, with specialrequirements extending that range to -55°to +150° C in special cases. In power sup-plies, achieving these operating tempera-

ture ranges requires a focus on component selection and environmental stress testing.

Shock and vibration : Power supplies usedin all types of military systems must standup to significant shock and vibration froma wide range of sources. Products for useon naval vessels must meet the shock spec-ifications of MIL-S-901 which can rangeup to 90gs. Vibration testing of electronicequipment like power supplies is gov-erned by MIL-STD-810, with individualregimens selected for each product inaccordance with its end use.

Thermal shock : Sudden extremechanges in temperature can significantly 

damage electronic systems includingpower supplies. MIL-STD-833 provides anumber of test regimens for cycling anassembly or component through rapidly changing temperatures. Typical test cyclesrange from 0° to +100° C, up to a maxi-mum of -65° to +150° C, with a minimum6 second interval between limits.

Humidity, moisture and condensing 

atmospheres : Water in all forms can sig-nificantly damage unprotected electron-ic equipment like power supplies. MIL-STD-810 governs ruggedizing electronicequipment to deal with all types of waterand related problems like fungus.Traditional solutions for dealing withcondensing atmospheres involve pottingthe power supply assembly by filling itscase with a non-conductive thermo-plas-tic material. This can add significant 

 weight to each unit which can be asevere design penalty in military systems

that fly or are mobile. Newer techniquesemploying innovative light-weight cir-

cuit board coatings and desiccants canpro vide the environmental isolation toprotect electronic circuits from moisture

 with a lower weight penalty.EMI and solar radiation : Military power

supplies must be able to withstand radia-tion of all kinds — from electromagnet-ic interference from other systems tosolar radiation from a sunspot event —

and continue to operate. MIL-STD-461governs a range of tests to ensure that power supplies can meet the noise rejec-tion challenges that they will encounter.

Looking ForwardMakers of military power supplies will

continue to meet the reliability chal-lenges imposed by the environmentaland electrical system standards that arenecessary when deploying military elec-tronics systems in the field. In thefuture, the issue of reliability might 

become less important than the devel-opment of a prognostic capability torecognize impending power supply fail-ures and notify the CPU embedded

 within the military system via a data linkto prepare for corrective action. Such asystem is not unlike those presently inmodern automobiles, where theonboard engine management systemdetects a defect like a misfire in cylin-der 3 and warns you with a checkengine light as you drive down the free-

 way. However, just as the introductionof these systems in the auto industry hasnot slowed the drive for ever-more-reli-able engines and components (in fact competitive pressures have greatly increased reliability), so the advent of failure detection systems for power sup-plies will not stop the quest for higherreliability power supplies.

Failure detection works well for sys-tems that are easily recovered, for exam-ple, with power supplies that are easily removed and replaced, and systemsdesigners should take this into consider-ation as part of their overall design

process. But when lives, important oper-ational capabilities, and significant amounts of money are at stake, knowingthat your power supply is going to fail isnot a comforting thing. There will alwaysbe a need in the military and in certainprivate industries for power supplies that can withstand rigorous power and envi-ronmental conditions to be there with-out fail when they are most needed.

This article was written by Ralph Livingstone, Chief Engineer, and Dave Newton,

 Design Engineer, Abbott Tech nologies (Sun 

Valley, CA). For more information, visit http://info.hotims.com/45600-401 .

An F-18 all weather fighter braves harsh conditions while landing on a storm-battered aircraft carrier.

An Ohio class nuclear submarine surfaces after an extended dive in the world’s most treacherouswaters.

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aero-online.org  February 2013

Airbus Looks

to the Future

Aluminum Makes a Comeback

Flight Display Trends

Top Technologies of 2012

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WHATEVERYOUR GAME, 3D PRINTING

IS GOING TO CHANGE IT.

22 Aerospace Engineering, February 2013

The Futur e of 3D Technology

3D technology is all around us. It’schanging how we design and manufac-ture products, make movies, heal our

bodies and interact with the world.Work that used to take place on a pageor screen now reaches into space. And

faster than ever before, 3D technologyis transforming our world.

To see the impact of 3D, look to the

realm of design. Designers led the wayin embracing 3D CAD and then 3Dprinting, incorporating more and morephysical models into their iterations

and thinking with their heads and theirhands. And they’ve reaped the benefits:design problems surface sooner and so-

lutions are less costly. Inspiration hap-pens faster. Ultimately, products are bet-ter and consumers are happier. Black &

Decker makes a safer tree trimmer andLamborghini makes a faster car because

reviews and trials are more frequentlyexecuted on models very much resem-

bling a final product.Now, 3D printing applications are ex-

panding from design into production,

and freeing manufacturers to buildwithout traditional restrictions. DDM

stands for direct digital manufacturing,a way to produce a finished product,part or tool straight from a computer

design. More importantly, DDM meansthe rewards of faster, leaner, smartermethods are coming to the production

floor. When we at Stratasys (and publi-cations like The Economist, Forbes andThe New York Times) call 3D printing“the next industrial revolution,” we’re

not exaggerating.A hundred years ago, the assembly

line changed the world with mass pro-

duction. It brought luxuries to the mid-dle class, good wages to workers andeconomies of scale to investors. Today,

companies like BMW already know thatDDM is mass production’s heir appar-ent. One factory-floor fixture, a name-

plate-application device, offers an ele-gant example. Liberated from tooling

From This Da y, Forward

 A few examples of the Stratasys 3D Printer line.

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Aerospace Engineering, February 2013 23

TMF O R A 3 D W O R L D

3D printing means

prototypes like these,

that help product designers

put their best foot forward.

They look like shoes. They feel like shoes. But they’re actually

prototypes. Printed layer by layer on a 3D printer. Every

day, 3D printing rewrites another rule of how things are made.

3D printers are at work in product design studios, engineering

departments and manufacturing plants. In schools and hospitals

matter. It is the next industrial revolution. And Stratasys is here

to lead it. Come explore the game-changing possibilities of 

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constraints, BMW engineers reducedthe device’s weight by half and replacedits blocky stock-metal handles with er-

gonomic grips — a great relief to work-ers who might lift the fixture hundredsof times per shift.

Today, NASA can shape a complex,human-supporting vehicle suitable forMartian terrain, despite the fact that its

parts are too complex to machine, toorapidly iterated to outsource and toocustomized for traditional tooling.

In a 3D world, we leave behind in-jection molding, casting and machin-ing, gaining economy without the

scale. 3D printing leads us beyondmass production and into mass cus-tomization. It’s how a researcher at aDelaware hospital creates a durable

ABS-plastic exoskeleton customized toperfectly fit one child, Emma, allowingher to play, explore and hug for the

first time. Then that researcher canmake a 3D-printed exoskeleton to fit adifferent child. And another. And a

dozen more. Now 15 children with raredisorders can raise their hands becauseof mass customization.

Ideas born today — your ideas — arefreer to solve problems faster than ever

before. Now, two innovators whohelped spark this revolution have fusedto lead the charge together, and more

great changes are at hand.Welcome to the new Stratasys, leader

of the next industrial revolution.

– B y David Reis, Stratas ys CEOThis rover includes about 70 FDM parts, includ-ing housings, vents and fixtures.

 A pediatric engineering research lab has developedand 3D-printed custom devices for their smallestpatients.

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Diesel aircraft coming soon to an airport near  you?

Recent developments of diesel technology have made thetwo-stroke, compression ignition engine an interesting op-tion for light aircraft manufacturers. Read more atwww.sae.org/mags/aem/11241.

UAVs shrink as technolog y growsAeroVironment says it achieved a technological milestone

never achieved before by building and flying a wing-flappingair vehicle, carrying its own energy source and using only two

flapping wings for propulsion and control. Read more at

www.sae.org/mags/aem/10587 .

Handheld ultrasonic camera ‘gun’ finds composite cracksNorwegian start-up’s easy-to-use nondestructive testing tech-

nology for carbon fiber-reinforced plastics has been adopted byEADS. Read more at www.sae.org/mags/aem/10548.

Countering the counterfeitersCounterfeit electronic parts affect safety and national secu-

rity, pose long-term reliability risks, and drive up sustainmentcosts. Read more at www.sae.org/mags/aem/11304.

Europe's aerospace sector at a crossroads

According to a report by the European Defence Agency, thecontinent is facing a massive black hole in its future defense pro-curement portfolio. Read more at www.sae.org/mags/aem/11363.

Avoiding traffic congestion in the airOnce aircraft are linked to satellites or ground-based sta-

tions, the design challenge shifts to disseminating signals topassengers. Read more at www.sae.org/mags/aem/11359.

Advantages of additive manufacturing begin to add upMetal-based, powder-bed additive manufacturing builds up

parts layer by layer, forming cross sections of the part in 20- to 80-

micron thicknesses. Read more at www.sae.org/mags/aem/11358.

Boeing engineers visualize technologies for manufacturingBoeing recently looked at the use of augmented reality as a

tool to help get design intent to the builder so the productcan build right the first time and every time. Read more atwww.sae.org/mags/aem/10715.

CAD, fasteners, projections, and qualit yToday, mechanics refer to drawings prepared by manufac-

turing engineers, using mark-ups on the part to provide refer-ence features and measurements, but there are problems withthis approach. Read more at www.sae.org/mags/aem/11053.

Composite structures pose EMI challengesThe all-composite commercial aircraft has become a reality,

and the need for the aircraft designer to consider electromagnetic

threats has also grown. Bombardier Core Electromagnetic Engineer-ing has conducted a lightning indirect effect measurements cam-

paign on different cylindrical barrels simulating all-metal and all-composite fuselages. Read more at www.sae.org/mags/aem/11335.

24 Aerospace Engineering, February 2013Fr ee Inf o at http://inf o.hotims.com/45600-804

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 What’s Online

Aer ospace Engineering’s Top Ar ticles of 2012

For modeling uniflow scavenged engines, researchers referenced a modernaircraft two-stroke turbocharged diesel power plant, named WAM 100/120,produced by Wilksch Airmotive, with a top brake power of 100-120 hp. A GT-Power model of the IDI engine was built and calibrated against experiments.

Examples of augmented reality work being done within Boeing.

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While it seems

the last six monthsof 2012, and espe-cially that last

quarter, were full of dread and doom interms of fiscal cliffs

and potential hitsto defense budgets,things have beenlooking relatively good for both commer-

cial airlines and the companies that sup-ply their fleet.

In fact, both the features in this issue

of Aerospace Engineering, the inauguralissue as a supplement to Defense TechBriefs, make reference to the ever-in-

creasing need for commercial aircraftover the next couple of decades.

As referenced in the feature “Ad-

vanced Aluminum Solutions for Next-Gen Aerospace Structures” on page 34,“Over the next 30 years, both Boeing

and Airbus project demand for approxi-mately 19,000-23,000 single-aisle air-craft like the 737 and A320. In additionto being able to achieve performance

improvements, any structural technol-ogy and material used to build these fu-ture aircraft must be capable of meeting

the required build rates.”While programs such as the Airbus

A350 and Boeing 787 have emphasized

and championed the increased use of composites in new aircraft, there are thosequite willing to say, “Not so fast.” Espe-

cially those in the aluminum industry.The feature, adapted from a technical

paper written by Alcoa engineers, goesinto some detail about the progress alu-

minum alloys have made over the past

few years, and the advantages for theiruse over composites. “Advanced alu-

minum and aluminum-lithium alloysenable improvements in structural per-formance while utilizing the current

manufacturing supply chain, reducingmanufacturing risk, and supporting ratereadiness.”

 Just as Airbus and Boeing agree there

will be an aggressive buildup of newaircraft to meet future market demands,it’s really not a stretch to imagine thatthere could potentially be some fore-

casters at both companies who alsoagree on a dread and doom outlook asto whether the supply chain will be

able to keep up with that demand.Alcoa does not seem to share that con-cern, at least when it comes to alu-

minum.In the feature on page 30 titled “2050

Vision,” the author quotes Airbus’ fore-

casts that “the world’s passenger aircraftfleets will increase by 109% over thenext 20 years. Some 28,200 new aircraftare expected to be delivered to meet

growth and replacement needs.” (Forthe record, Boeing believes the figure ismore like 34,000 aircraft over the next

20 years, 41% of which will replaceolder, less efficient planes; 59% will benew deliveries.)

Whatever the actual figure of aircraftover the next 20 years, the “2050 Vi-sion” feature offers up a good point or

two. “With existing efficient airplanedesigns likely to continue in produc-tion for at least the next two decades,the next-generation follow-up civil pro-

grams will not only have to offer trulybreakthrough performance, but be justone component in a transformed civil

aviation infrastructure.”The feature details Airbus’ future con-

cepts studies, and looks not at just what

we will fly, but how we will fly in 2050and beyond, and the technologies andchanges that will be needed to allow it

to happen. In essence, while the num-

ber of aircraft over the next 20 year willcontinue to increase, so must the ex-

tent of the technologies that will allowthem to remain, or become, sustainableand viable.

 Jean L. Broge Managing Editor 

Editorial

Change is in the Air 

Thomas J. Dr ozdaDirector of Programs& Product [email protected] JostEditorial Director  Jean L. Br ogeManaging Editor Lindsa y Br ookeSenior Editor Patrick Ponticel

 Associate Editor R yan Gehm

 Associate Editor 

Matt Monaghan Assistant Editor 

Lisa ArrigoCustom ElectronicProducts Editor Kami BuchholzDetroit Editor Richard Gardner European Editor  Jack Yamaguchi Asian Editor Contributor sTerry Costlow, JohnKendall, Bruce Morey,Jenny Hessler, Jennifer Shuttleworth, Linda Trego,

Stephen Ashley

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Gr eat Lakes andSoutheast: OH, MIMidwest: IA, IL, IN, KS,Manitoba,MN, MO, MT,ND, NE, SD, WI, WY, AL,KY, MS, FL, GA, NC, SCOntario CAN, TNChris Kennedy x3008+1.847.498.4520

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26 aero-online.org Aerospace Engineering, February 2013

Technology Update

WIMPs and the Future of Flight Displa ys

Today, interactive glass cockpitdisplays in aircraft look and behavevery similarly to other computers,

with windows and data that can bemanipulated with point-and-clickdevices. As we see a growing adop-

tion of natural, or post-WIMP(windows, icons, menus, pointer),HMIs in the general market — suchas in smart phones, tablets, music,

or video players — cockpit displaysystem (CDS) suppliers are prepar-ing now for the cockpits of the fu-

ture, which will place the pilot atthe center of the system. This ob-jective will be achievable only if 

the proper engineering and designprocesses are deployed in conjunc-tion with the proper development

tools.WIMP is often incorrectly used as

an approximate synonym of graphi-

cal user interface (GUI). Any inter-face that utilizes graphics can betermed a GUI, and WIMP systemsare a derivative of such systems.

However, while all WIMP systemsutilize graphics as a key element(namely, the icon and pointer ele-

ment) and therefore all WIMPs areGUIs, the reverse is not true — someGUIs are not WIMPs.

The primary benefit of WIMP sys-tems is to improve the HMI by en-abling better ease of use for non-

technical people, both novice andpower users. Know-how can beported from one application to thenext, given the high consistency be-

tween interfaces.

Due to the nature of the WIMPsystem, simple commands can be

chained together to undertake agroup of commands that wouldhave taken several lines of com-

mand line instructions. For the av-erage computer user, the introduc-tion of the WIMP system has

allowed for an expansion of usersbeyond the potential possible underthe previous command line inter-

face (CLI) systems.User interfaces based on the WIMP

style are very good at abstracting work-spaces, documents, and their actions.

Their analogous paradigm to docu-ments as paper sheets or folders makes

WIMP interfaces easy to introduce tonovice users.

Furthermore, their basic representa-tions as rectangular regions on a 2D

flat screen make them a good fit forsystem programmers. This explains

 An example of a glass cockpit. In most modern commercial airplanes, including the A380, A350, and 787,the traditional “widget-based” (or WIMP) approach is mostly used for interactive cockpit displays.

The evolution of user interfaces. While all WIMP systems utilize graphics as a key element and thereforeall WIMPs are GUIs, the reverse is not true: some GUIs are not WIMPs.

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why the paradigm has been prevalent for more than 20 years,both giving rise to and benefitting from commercial widget

toolkits that support this style.However, several researchers consider that there are appli-

cations for which WIMP is not well suited. This includes any

application requiring devices that provide continuous inputsignals, showing 3D models, or simply portraying an interac-tion for which there is no defined standard widget. These in-

terfaces are called post-WIMP GUIs.Post-WIMP comprises work on user interfaces, mostly

GUIs, that attempt to go beyond the paradigm of WIMP in-terfaces, which are not optimal for working with complex

tasks such as computer-aided design (CAD), working on largeamounts of data simultaneously, or complex interactive sys-tems. Post-WIMP interfaces have today made their way to

the general public, including portable music players, smartphones, tactile tablets, and ATM screens.

Today most operational and flying cockpit HMIs, as the

majority of desktop computers, are still based on WIMP in-terfaces — some of them standardizing upon the ARINC 661international standard for interactivity management — and

have started undergoing major operational improvementsto surpass the hurdles inherent to the classic WIMP inter-

face. These include the exploration of virtual 3D space, andnatural interaction techniques for window/icon sorting,

focus, and embellishment.A natural user interface (NUI) is the common parlance used

by designers and developers of HMIs to refer to a user inter-

face that is (1) effectively invisible, or becomes invisible withsuccessive learned interactions to its users, and (2) is based onnature or natural elements (i.e. physics).

The word natural is used because in reverse, most computer

or industrial interfaces use artificial control devices whose op-eration has to be learned. A NUI relies on a user being able toquickly transition from novice to expert. While the interface

requires learning, that learning is eased through design thatgives the user the feeling that they are instantly and continu-ously successful. Thus, natural refers to a goal in the user ex-

perience — that the interaction comes naturally while inter-acting with the technology, and that the interface itself isnatural.

An example of a strategy for designing a NUI is the strictlimiting of functionality and customization so that usershave very little to learn in the operation of a device. Provided

that the default capabilities match the user's goals, the inter-face is effortless to use.

In the early days of CLI, users had to learn an artificialmeans of input — the keyboard — and a series of codified

inputs that had a limited range of responses, where thesyntax of those commands was strict. Then, when themouse enabled the GUI, users could more easily learn the

mouse movements and actions and were able to explorethe interface much more. The GUI relied on metaphors forinteracting with onscreen content or objects. The "desktop"

and "drag" are examples, being metaphors for a visual inter-face that ultimately was translated back into the strict cod-ified language of the computer. NUIs intend to provide di-

rect and intuitive interaction between the user(s) and thesystem(s).

As far as aerospace is concerned, in today's most moderncommercial airplanes, including all recent Airbus and Boe-

ing planes (such as the A380, A350, and 787), the tradi-tional “widget-based” (or WIMP) approach is mostly usedfor interactive cockpit displays. The main reasons, among

many others, are the system certification needs for the high-

est levels of safety for these CDSs, which often require theuse of already mature and trusted technology, but also some

kind of “resistance to change” from crews and pilots — thusairline companies — who are used to flying with traditionaluser interfaces in the cockpit.

This article is based on SAE technical paper 2012-01-2119 by 

Vincent Rossignol, Esterel Technologies, and Christophe Bey, EcoleNationale Supérieure de Cognitique. Visit http://papers.sae.org/ 2012-01-2119/ to view the full paper.

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30 aero-online.org Aerospace Engineering, February 2013

While aircraft cruising speeds

have not changed signifi-cantly since jet air trans-port operations began in

the late 1950s, overall journey times areactually getting longer in many cases asair traffic and airport delays are increas-ing at the world’s busiest airport hubs.

Airbus global market forecasts indi-cate that the world’s passenger aircraftfleets will increase by 109% over the

next 20 years. Some 28,200 new aircraftare expected to be delivered to meetgrowth and replacement needs, but that

is only up to the year 2031. Boeing pre-dicts similar numbers up to that time.

How will the world be able to accom-

modate so much demand for air travel?With existing efficient airplane de-

signs likely to continue in productionfor at least the next two decades, the

next-generation follow-up civil pro-grams will not only have to offer trulybreakthrough performance but, Airbus

suggests, be just one component in atransformed civil aviation infrastruc-ture, as different from today’s aviation

scene as were the early pioneering dayswhen jets first appeared in passengerservice.

Airbus said that its future conceptsstudies are focusing not just on what

we will fly, but how we will fly in 2050and beyond.

“Our engineers are continuously en-couraged to think widely and come up

with ‘disruptive’ ideas that will assistindustry in meeting the 2050 targets wehave signed up to,” said Charles Cham-

pion, Executive Vice President of Engi-neering at Airbus. “Tough environmen-tal targets will only be met by a

combination of investment in smarteraircraft design and optimizing the envi-ronment in which aircraft operate.”

Significant improvements couldcome from new aircraft design, alterna-tive energy sources, and new ways of flying: Airbus’ Smarter Skies vision for

2050 highlights five concepts, includ-ing eco-climb, optimized free-flight,free-glide approaches, low-emissions

ground operations, and new energy

usage.

Assisted Takeoff Today, those countries with plenty of 

spare land, such as China and the desertnations of the Middle East, aspiring tobecome global hubs, appear happy tocover vast areas in new runways and

terminals to meet future expansionneeds.

But many developed countries —

even large ones — find that it is not soeasy politically, as well as physically, to

find the space for new runways at air-ports that historically have been sited

relatively close to busy cities, with all

the infrastructure close by, serving notonly passengers and freight operatorsbut also the thousands of people whoactually work at and supply the day-to-

day needs of those airports. At suchhubs, and as mega-cities become a real-ity, land is at a premium. So, a new ap-

proach will be required, such as usingshorter runways.

Airbus has examined a radical idea

that involves aircraft launched throughassisted takeoffs using renewably pow-ered, propelled acceleration. It claims

this could lead to steeper climbs fromthe runway, with less noise and fastertimes toward cruise altitudes.

When quizzed recently by  Aerospace

 Engineering on the g-forces involved —

as an aircraft-carrier-style launch mightnot be too sensible for senior citizens or

those of a nervous disposition — Cham-pion said that the acceleration wouldbe gradual and within the acceptable

limits established for civil aircraft andcabin seat requirements.

Although technical details remained

vague, it was suggested through a seriesof computer-generated video sequencesthat such launches would involve the

aircraft taxiing onto a special launchcradle that would project the aircraft

into the air at the appropriate V1 posi-tion where it would climb at a high

2050 VisionAirbus provides a far-ranging, thought-provoking look at some of the changes the commercial aerospace industry might expect 

to see by 2050.

by Richard Gardner, Contributing Editor 

Impression of an Airbus concept plane lifting off from its launch cradle.

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 Aircraft Feature

angle using the thrust of its own en-gines. Presumably, the launch cradles

would have to return to the start pointrapidly after each takeoff, either bybacktracking down the runway, or per-

haps on a return loop, so there is al-ways one waiting to be used at the start.How this would work was not ex-

plained, though the system would behighly automated and would have tobe extremely reliable to avoid the air-port coming to a standstill if a break-

down occurred.The futuristic “Airbus Concept Plane”

featured in the videos keeps the landing

gear detail out of sight, but a conven-tional landing gear could not be deletedfrom the design, as there would be an

operational need to move around at theairports and also to serve destinationsthat might not be fitted with handling

cradles and associated automatedlaunch aids.

The advantages of having jet aircraft

with no landing gear, in terms of savingweight and allowing automated han-dling movements, were extensively andquite successfully tested (using small

military research jets) in the 1940s and1950s in the U.K. and U.S., but they allproved to be too inflexible in use com-

pared to aircraft with conventionalwheeled landing gear, and the R&D pro-grams were abandoned.

For the Airbus eco-climb concept towork, there would have to be globalagreement on the use of standard take-

off launch systems, but reliability andthe cost of providing, operating, andmaintaining the ground systems wouldhave to be acceptable to airport and air-

line operators.

Despite the obvious technical, safety,and commercial challenges to be faced

and overcome, this remains an excitingidea that might offer a way of breakingout of the traditional runway planning

straightjacket.

Toward Free-FlightNo less radical, but perhaps more

likely, Airbus envisions fully exploitingdevelopments in air traffic management

(ATM) systems and procedures to allowaircraft to “self-organize” and select the

most efficient and environmentallyfriendly routes (so-called free-flight),

making optimum use of prevailingweather and atmospheric conditions.

The aircraft would have highly intel-ligent, integrated onboard systems toselect the most appropriate flight path

and altitude, while using networkeddata for greatly enhanced situationalawareness, incorporating navigation,

communications, and collision avoid-ance information. This data would beused by the aircraft to fly the best path

automatically, but the pilot would befully in the loop at all times.

In technical terms, such comprehen-sive free-flight capability from pre-take-

off to arrival would not require humanintervention. However, while a civil

UAV could be introduced today, passen-ger acceptance would probably alwaysdemand a human in the cockpit, and

that would probably mean two pilotson board, even if only one was needed.

On high-frequency routes between

the biggest hubs, Champion said thatadvanced automated systems couldallow aircraft to benefit from flying in

formation like a flock of birds duringthe cruise phase of a long flight, bring-

ing efficiency improvements due todrag reduction and lower energy use.

The future aircraft in its continuous eco-climb.

Impression of future aircraft in 2050 flying in free-flight and a formation flock along a long-haulexpress skyway.

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32 aero-online.org Aerospace Engineering, February 2013

2050 Vision

This would only be practical onmedium- to long-haul sectors, but au-tomated collision avoidance and sta-

tion-keeping capabilities could enableclusters of airliners to make greater useof any given block of sky, increasing

the total volume of air traffic that couldbe handled in the future.

Onboard sensors and satellite-en-abled navigation and formation-keep-

ing systems would enable very precise3D flight positioning to be maintained,with weather factors and other air traf-

fic movements built into the programs.

A Free-Glide ApproachAnother concept studied by Airbus

involves low-noise, free-glide ap-proaches and landings to reduce envi-

ronmental impact and fuel consump-tion. This might make a more useful

contribution at existing airports situ-ated near large urban communities. Itwould seem that off-shore airports andthose in deserts might not see muchadvantage other than perhaps allow-

ing a faster turnaround of incomingflights.

Aircraft allowed to take free-glide ap-

proaches into airports would reduceemissions during the overall descent,and also reduce noise during a steeper

approach as there would be no need forengine thrust or air braking. Such ap-

proaches would reduce landing speedearlier, which would make shorter land-

ing distances achievable with less run-way length needed.

If the approach angle is steeper, but

the landing speed lower (which doesnot sound logical), it must be assumedthat new-generation aircraft intendedfor an in-service 2050 timeframe would

incorporate advanced aerodynamic fea-tures to allow for both assisted takeoffsand free-glide landings without elabo-

rate lift and air-braking devices, whichwould increase noise. Perhaps somekind of wing morphing, using new ma-

terials and structural properties, might

be perfected by then to make suchmovements a practical possibility.

Another Airbus concept entails low-emissions ground operations that wouldinvolve automated systems to deliver

aircraft to and from the runway and ter-minals. On landing, aircraft engineswould not be used for taxiing, runwayscould be cleared quicker, and ground

handling emissions could be cut.Advanced technology could optimize

an aircraft’s landing position with suffi-

cient accuracy for an autonomous, re-newably powered taxiing carriage to beready so aircraft could be transported

away from the runway quicker, also op-timizing terminal space and removingrunway and gate limitations.

Airlines are already looking veryclosely at emerging self-taxi systems tosave time and fuel, either through a self-contained geared taxi drive on the land-

ing gear itself, or via a “clip-on” taxi-tugthat takes the aircraft between runwayholding areas and the boarding dock.

What Airbus is suggesting is a built-in,automated, eco-friendly taxiing system,almost like a tramway, using computer-

controlled mini-tugs that could run fullyautonomously serving extensive termi-nals and satellite systems. This might re-

quire special dedicated tracks or roadsfor the tug devices to reposition them-selves at the runway end of the cycleafter each operational movement with

Future aircraft preparing for free-glide approach to reduce fuel, noise, and emissions.

 Aircraft in free-flight formation to maximize cruise efficiency.

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Aerospace Engineering, February 2013 33

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 Aircraft Feature

the aircraft, but the task should bestraightforward to design and establish,

and could be used for any aircraft.It might help if agreed operating stan-

dards and fittings for future aircraft could

be adopted as early as possible, as thiscould eventually become a global “must-have” requirement even before 2050.

Seeing the FutureThe fifth and final element in the Air-

bus 2050 vision is the use of sustainablebiofuels and other potential alternativesources to secure supply and further re-duce aviation’s environmental footprint

in the long term. The company believesthat this will allow the extensive intro-duction of regionally sourced renewable

energy close to airports, feeding bothaircraft and infrastructure requirementssustainably.

Airbus is playing a leading role todayin working with the energy industry andother partners on alternative fuels, as

well as advanced aerodynamics and sup-porting new aero engine and ATM sys-

tem developments. Airbus believes that if the ATM and technology aboard aircraftwere optimized (assuming 30 million

flights per year), flights in Europe andthe U.S. could on average be 13 minutesshorter, with similar savings elsewhere in

the world. This would save around 9 mil-lion t of excess fuel annually, which inturn equates to over 28 million t of avoid-able CO2 emissions, and a saving of 5

million hours of excess flight time.The U.S. NextGen and European

SESAR programs are both aimed at en-

hancing the performance of the ATMsystem through the better use of aircraftcapabilities and changes in infrastruc-

ture and organization on the ground.The ultimate aim of these initiatives isto reduce air traffic congestion and de-

lays, and also to allow more directflights, better flight profiles, and a re-duction in the cost of air navigation

services using advanced technologiesand communications.

“Our focus on meeting continuousgrowth in demand is to keep the pas-senger, our customers, and the environ-

ment at the center of our thinking,”said Champion. “The future of sustain-able aviation is the sum of many parts,and success will require collaboration

amongst all the parties who are passion-ate about ensuring a successful prospectfor aviation.”

If aviation is currently pausing on awell-tested technology plateau, there willsurely come a time in the not-too-dis-

tant future when a whole new series of innovative developments will arrive andchange everything as we know it today.

The Airbus Smarter Skies vision givesus just a glimpse of how different thefuture of aviation might be, but this isbased on some sound research and seri-

ous study. The reality might be evenmore far-fetched than we can imagine.

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34 aero-online.org Aerospace Engineering, February 2013

AdvancedAluminumSolutions f or 

Next-GenAer ospaceStructur es

Airline competitiveness and the

demand for improved aircraftperformance and affordability(acquisition and operational) are

driving advancements in technologies

that can enable these improvements.Improvements in engine technology,

aerodynamics, systems, and structural

performance all have the effect of im-proving aircraft efficiency and reducingfuel costs. Extending inspection intervals

and improving aircraft durability lead toreduced maintenance costs. These per-formance improvements also need to be

delivered at a cost that solves the airlinebusiness case. From the airframer’s per-spective, these technologies need to bereadily scalable to large-scale manufactur-

ing and support the expected build rates.While carbon fiber-reinforced polymer

(CFRP) was chosen for the primary wing

and fuselage structures of the most re-cent, all-new, twin-aisle aircraft — Boeing's787 and Airbus's A350XWB — structural

material choices are not so definitive fornew and derivative single-aisle aircraft.

Bombardier chose an advanced alu-minum fuselage combined with CFRP

wings for the CSeries. The original Mit-subishi design for the MRJ included aCFRP wing. Mitsubishi has since re-

designed the MRJ to utilize an aluminumwing box. Airbus and Boeing decided tokeep an aluminum-intensive airframe

when they made their decisions to de-velop the A320neo and 737 MAX.

Advanced aluminum and aluminum-

lithium (Al-Li) alloys enable improve-ments in structural performance whileutilizing the current manufacturingsupply chain, reducing manufacturing

risk, and supporting rate readiness. Re-searchers from Alcoa have focused onthe applicability of these advanced alu-

minum alloy products for single-aisleaircraft such as the 737 and A320.

The Aluminum MixThe first aluminum-intensive aircraft

in the early 20th Century utilized a sin-

gle alloy. As aircraft design and alloy de-velopment capabilities progressed, alu-

minum alloys, products, and tempers

were optimized for specific applications.Advanced aluminum alloys take ad-

vantage of alloy composition and pro-cessing parameters to achieve the combi-

nations of strength, damage tolerance,and corrosion resistance necessary to en-able improved structural performance.

These advanced alloys represent conven-tional 2000 and 7000 alloys. Addition-ally, many of these advanced alloys uti-

lize lithium as an alloying element.The use of Al-Li alloys is not new in

aerospace. One of the earliest Al-Li al-

loys, 2020, was developed and foundapplications in the late 1950s. Whenalloyed with aluminum, lithium re-

duces the density, increases the modu-lus, improves fatigue crack growth per-formance, and acts as a strengtheningagent.

Early Al-Li alloys had high levels of lithium as alloy designers sought tomaximize density reductions. These

high levels of lithium also resulted inpoor manufacturing characteristics, cor-rosion, and damage tolerance perform-

ance for these alloys.Development of third-generation Al-

Li alloys has focused on lithium addi-

tions for strength and fatigue crackgrowth improvements with more bal-

anced alloy performance. By reducingthe lithium content and optimizing

thermomechanical processing, many of the shortcomings with the previous Al-Li alloys can be overcome.

The Product MixFuselage skins support the structural

loads from the payload as well as main-tain the cabin pressure. The key mate-rial requirements for fuselage skins are

toughness, damage tolerance, and staticstrength. In addition to the structural

requirements, corrosion can also be aconcern in the fuselage, especially in

This chart shows the progression of aluminum alloy and temper implementation for aerospace appli-cations. Over time, alloy and product development have become focused toward specific applications.

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Materials Feature

the belly sections where moisture canaccumulate during service.

A more recently developed incumbentalloy, 2024-T3 sheet, is the baseline sheetalloy for single-aisle fuselage structures.

It has a good combination of strengthand toughness. To protect against corro-sion, a thin layer of pure aluminum, al-

clad, is added to the surface.The wings provide the lift for the air-

craft and support the full weight. The

upper and lower covers, joined by sparsand ribs, form a beam that supports the

aerodynamic loads, keeping the aircraftin flight. The wing covers of the 737and A320 aircraft consist of a plate skin

with fastened, extruded stringers.The bending loads on the wing cause

the upper cover to be loaded in com-pression and the lower cover to be

loaded in tension. The principal mate-rial requirements for upper wing plate

and extrusion products are compres-sion strength and modulus. The princi-

pal material requirements for lowerwing plates and extrusions are tensilestrength and damage tolerance to with-stand the fatigue loads.

Advanced upper wing products in-clude conventional alloys, such as 7255plate, with increased strength and fa-

tigue properties. Al-Li products, like2055 plate and extrusions, enable com-

The material properties for advanced fuselage sheet alloys are shown as aratio of alclad 2524-T3 material properties.

Key material properties for advanced upper wing plate products are shownas a ratio of 7055-T7751.

Comparison of key properties for advanced lower wing extrusion productscompared to 2024-T3511.

This chart shows the comparative specification minimum longitudinal yieldstrength as a function of thickness for 7085 forging and plate products com-

pared to 7050 forging and plate products. The 7085 alloy is able to achievehigher strengths in thicker sections.

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36 aero-online.org Aerospace Engineering, February 2013

 Advanced Aluminum Solutions

parable strength with increased stiff-ness and reduced density.

Improvements for lower wing alloysfocus on increased static strength anddamage tolerance, including toughnessand spectrum fatigue crack growth, to

enable increased inspection and main-tenance intervals. Both conventionaland Al-Li alloys have been developed

that offer performance improvementsover the existing structures.

Modern aircraft designers are taking

advantage of developments in high-speed machining to reduce structuralweight and cost by implementing

monolithic and integrally machinedstructures. Monolithic designs are being

used to replace built-up structures. Ex-ample parts are fittings, bulkheads,wing ribs, and beams. The variety of parts corresponds to a variety of designdrivers and material requirements. Typ-

ically, the material requirements arestrength with an acceptable level of toughness and fatigue performance.

Seat tracks, floor beams, and stan-chions are strength- and stiffness-drivencomponents. High-strength aluminum

alloys such as 7178-T6511 and 7150-T77511 have traditionally been em-

ployed in these applications. The floorstructure is also exposed to moisture

and liquid, presenting the need for cor-rosion resistance. The combination of strength, density, modulus, and corro-

sion performance of third-generationAl-Li alloys makes them ideally suitedfor use in floor structures.

Manufacturing MixOver the next 30 years, both Boeing

and Airbus project demand for approxi-mately 19,000 to 23,000 single-aisle air-craft like the 737 and A320. In addition

to being able to achieve performanceimprovements, any structural technol-ogy and material used to build these fu-

ture aircraft must be capable of meetingthe required build rates.

The notable difference in productionof Al-Li products compared to conven-tional alloys is the ingot casting prac-tice and facilities. Because of the chem-ical reaction of lithium with oxygen, it

is necessary that Al-Li alloys are cast inan inert atmosphere, using specializedequipment and corresponding dedi-

cated casting facilities. Conventionalcasting facilities cannot be used for Al-Li alloys.

Alcoa and other aluminum manufac-turers have recently announced devel-

opment and expansion of aluminum-lithium casting facilities. This ex pansion

will increase the availability of Al-Liingot for aerospace applications. Oncethe raw ingot or billet is cast, the re-

mainder of the Al-Li plate, forging,sheet, or extrusion production flow pathis similar to the conventional alloys of 

the same product form.The processing of the Al-Li ingots

takes place in the same factories and on

the same production equipment andtooling as conventional, non-lithiumalloys. Although the Al-Li products run

alongside the conventional products,the specific thermal-mechanicalprocesses required to achieve the de-sired properties are optimized specifi-

cally for each alloy and product. It is

not expected that investments specificto Al-Li alloys would be required at

sheet, plate, forging, or extrusion millsto support future build rates.

While early generations of Al-Li had

poor machining characteristics, the cur-rent, third-generation alloys are signifi-cantly improved. Machining trials at

Alcoa and multiple end users havedemonstrated machining success of Al-Liproducts using the same tools, machines,and techniques as are used for conven-

tional aluminum alloys. For example,

these Al-Li products can be machinedusing both carbide and high-speed steel

Plot comparing characteristics of advanced plate products for machinedparts. The variation in key properties across the alloys enables optimizationfor a variety of applications.

Plot comparing the relative performance of advanced high-strength extru-sion alloys to 7150-T77511 for use in floor structures.

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Aerospace Engineering, February 2013 aero-online.org 37

Materials Feature

tooling. It has been shown to be capableof both conventional machining and

high-speed machining. While specificparameters will need to be optimized forthe alloy, product forms, and part geom-etry, similar speeds, feeds, and depths of 

cut can be used.Tooling wear studies were done com-

paring 2099-T83 extrusion to other

commonly machined alloys. Testingfollowed ASTM E618-81 and resultsshowed that the amount of tool wear

observed for the 2099-T83 extrusionwas less than half that of 2024-T351plate. The surface finish on the 2099-

T83 parts was excellent throughout.Cooling and lubrication using both

oil- and water-soluble coolants haveworked well, with both conventional andminimum quantity lubrication (MQL)techniques. Machinists also report thatthe Al-Li alloys have good chipping char-

acteristics. However, dry machining isnot recommended. MQL should be uti-lized if dry parts are required.

Another consideration for producibil-ity of machined parts is machining dis-tortion, which is caused by residual

stresses and can be prevented by usingstress-relieved material. The 7050-T7451

plate is an example of a stress-relievedproduct that has gained widespread ac-

ceptance because of good machining per-formance and low distortion.

The 7085 and 7065 plate and forgingproducts presented are stress relieved.Advancements in forging analysis, tool-

ing design, and press capability, includ-ing Alcoa's large 50,000-MT press, haveenabled stress relief of large and com-plex forgings, enabling repeatable ma-

chining of monolithic parts with re-duced distortion.

The Al-Li products presented here are

used in a -T8 temper. The -T8 temperdenotes that cold work is required toachieve target mechanical properties.

Much like -TX51 tempers in 2xxx and7xxx alloys, the cold work imparted aspart of the T8 temper and associated

stress relief will contribute to successfulmachining operations. This has beendemonstrated in practice by many cus-tomers who have successfully machined

Alcoa's 2099, 2055, and 2060 extrusionand plate alloys.

Many applications, such as fuselage

and wing skins, require forming tomeet dimensional requirements.Formability in the final -T8 temper may

be limited. In most cases, the materialwill be aged to the final -T8 temper atthe producing mill. However, for appli-

cations where the desired contour can-not be achieved in the -T8 temper, theproduct can be provided in an interme-

diate temper to facilitate customerforming operations.

For applications with small amountsof contour, such as wing skins and

stringers or constant section fuselageskins, the Al-Li alloys have been success-fully chip formed and brake formed. Age-

creep forming parameters have been de-

veloped for the 7255 plate product. Forsections requiring more complex curva-

ture than what can be achieved in thefinished temper, stretch forming in the -T3 temper and subsequent aging to the

final -T8 temper is an option.Stretch-forming trials of 2060-T3 sheet

and 2099-T3 extrusions have demon-strated capability to achieve the desired

contours. Forming limit diagrams for2060-T3 sheet indicate that the materialshould have improved stretch-forming

capability to 2524-T3 sheet. However,

because a minimum amount of coldwork is required to achieve target prop-

erties, stretch forming and post-formingaging parameters need to be developed

to ensure performance requirements aremet in the finished product.

Providing surface finishes to protectagainst corrosion is common practice

in the aerospace industry. Experienceshows that surface treatment and chem-ical operations can be successfully con-

ducted on Al-Li alloys. Alcoa hasdemonstrated anodizing, conversioncoating, priming, and finish top-coatpainting operations on third-genera-

tion Al-Li alloys using conventionalprocesses.

Trials on 2099 plate and extrusionsinvestigated pretreatment, deoxidiza-tion, and etching, followed by anodiz-ing, priming, and painting operations.

Throughout the trials, 2099 plate andextrusion specimens passed the samerelevant quality control tests as the

baseline 7075 and 2024 alloys.Throughout this testing, the sameprocess baths were used for 2099 as well

as 7075 and 2024 alloys. There was nodegradation of the chemical baths ob-served due to the Al-Li alloys. After pro-cessing, both the Al-Li and the non-

lithium products met the pertinentspecification and quality assurance re-quirements. Al-Li alloys can be

processed in the same baths as conven-tional alloys. This has been demon-strated for chromic acid anodize, phos-

phoric acid anodize, and boric sulfuricacid anodize processes.

For 2060 sheet, it has been observed

that when processing mill finish sheet(not machined, with the mill finish oxidelayer still on the surface) the pre-treat-ment and chemical processes need to be

optimized to remove the oxide layer.Once the optimized process is incorpo-rated, the 2060 sheet successfully passes

anodize and conversion coating specifi-cation requirements. This optimization isapplicable to the surface preparation

when the mill finish oxide is intact. Oncethis oxide layer is removed, conventionalprocesses can be applied.

This article is based on SAE technical

 paper 2012-01-1874 by Brandon Bodily, Markus Heinimann, Gary Bray, Edward Colvin, and Jeffrey Witters of Alcoa. Visit 

http://papers.sae.org/2012-01-1874/ toview the full paper.

This figure shows chromic acid anodized2060T8E30 sheet specimens after 336 h corrosiontesting exposure in ASTM B117 in accordancewith MILA-8625F. All specimens passed.

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38  www.defensetechbriefs.com Defense Tech Briefs, February 2013

An Improved SDR FPGA Verification Methodologyfor Emerging OFDMA Waveforms

The rapid evolution of commercial tech-

nologies such as Long Term Evolution(LTE) is becoming more attractive for

Software-Defined Radio (SDR) and pub-lic safety applications [1,2]. They have thepotential to support high data through-put applications with scalable subcarri-ers and the use of multiple antenna tech-niques such as Multiple-Input Multiple-Output (MIMO) technology.

The complexity of commercial Orthog- onal Frequency Division Multiple Access(OFDMA) waveforms such as LTE, how-ever, poses significant challenges for

SDR physical layer baseband develop-ment in which a common platform may be required to support multiple wirelessformats. The baseband coding anddecoding required for these waveformsare complex, and may require animproved design and verificationmethodology to ensure that FPGA test  vectors are consistent with commercialimplementations before customizing the waveform for potential SDR applicationssuch as secure military communications.

For example, an issue with the imple-

mentation on a CRC (cyclic redundan-cy check) encoding block can result inmany errors downstream at each subse-quent coding stage. Tracing the errorback to the CRC coding block can bedifficult unless test vectors can be com-pared to reference vectors at eachstage. Similarly, a simple sign reversalfor an FPGA FIR (finite impulseresponse) tap coefficient may result ina demodulation problem that would bemeasured as Error Vector Magnitude(EVM) at the output of an SDR’s RF

transmitter. At first glance, one might assume that a demodulation issue at the transmitter’s output would be anRF issue. However, probing the EVM at 

 various stages along the mixed-signal/RF transmitter chain (RF, IF,I/Q, digital) may trace the problemback to the FPGA section. Further-more, probing at different stages withinthe FPGA implementation can help topinpoint the problem in the FPGA implementation.

This article discusses an improved

methodology to verify FPGA implemen-tations for complex OFDMA waveformssuch as LTE. This improved methodolo-gy will show how simulated LTE refer-ence vectors can be used to ensure aconsistent interpretation with commer-cial LTE configurations. The commer-cial LTE reference vector simulationblocks can also be customized for poten-tial SDR applications such as secure mil-itary communications. In addition, Vector Signal Analysis (VSA) measure-ment software will also be used on a

logic analyzer to probe within an FPGA design to ensure that the FPGA imple-mentation can be demodulated with the

 VSA software at various test points with-in the FPGA implementation.

FPGA Development:Today’s Existing Approach

FPGA developers typically start withsystem specifications that include behav-ioral requirements. These specifications

 will likely have some level of mathemati-cal or pseudo-code representation, andmay be part of a wireless standard that isstill evolving and incomplete.

The FPGA development team willinterpret these specifications and may develop their own reference models togenerate stimulus inputs and expectedoutputs. These values, often called test 

 vectors, can be used in testing of theHDL code used to generate the actualdesign through synthesis and backendmap, place, and route tools.

Today’s OFDMA technologies such asLTE support many configurations, which can make it time-consuming and

difficult to generate test vector refer-ence models to support the many con-figurations. For example, LTE is scalablein which the number of subcarriers

 varies with the channel bandwidthselected (1.4, 3, 5, 10, 15, or 20 MHz). Inaddition, there are many coding config-urations and modulation configurationssuch as QPSK, 16QAM, and 64QAM.

Generating LTE reference test vectorscan present significant development timeoverhead for the FPGA engineer, giventhe many configurations supported by the

LTE standard. Complex blocks, such asthe Turbo coder/decoder, may involve

Figure 1. Using S ys temVue LTE tes t  vector references for HDL code  verificat ion and FPGA hardware

 tes t ing.

Figure 2. Using HDL co-simulat ion in S ys temVue for debugging.

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significant time to create a behavioral test  vector reference from scratch. Unfor-tunately, this can extend the development time already required for the primary taskat hand — writing the HDL code for theactual FPGA implementation.

In addition to the development timeoverhead, there can be significant riskassociated with this approach: the FPGA 

developer is writing/creating their ownbehavioral verification vectors to checktheir own HDL code. This is analogousto an author writing their own spell-checker. If an author is unsure about thespelling of a word, or convinced that a

 word is spelled in a particular manner,then spell checking with a self-writtenspell-checker can be ineffective in verify-ing the spelling. The same holds true forFPGA development. If the LTE standardis misinterpreted when writing the HDLcode, the same misinterpretation may be

repeated when creating the behavioral vector reference.

Configurable Reference Test Vectors An independent test vector reference

conforming to the LTE standard, whichis parameterized and configurable forthe many supported LTE configurations,can help address these challenges.

This is illustrated in Figure 1, where

 vectors are generated with the inde-pendent test vector reference using thesame stimulus that is applied to theHDL simulator. The HDL simulator out-put is then compared to the independ-ent test vector reference to verify that they agree behaviorally.

If they do agree, the interpretation of the wireless standard is consistent. If 

they don’t agree, further de-bugging can

be performed with the intermediatenodes of the independent test vector ref-erence. The LTE reference blocks areconfigurable for the many configura-tions supported by LTE (e.g. different channel bandwidths, coding configura-tions, and modulation types).

Furthermore, the simulated test vectorreference algorithms can be customized

Defense Tech Briefs, February 2013 39Free Info at http://info.hotims.com/45600-809

Figure 3. LTE I/Q modulator implemen tat ion on FPGA de velopmen t board. Lef t: DAC ou t pu t meas-ured by Infiniium oscilloscope and  V SA sof tware, and righ t: FPGA digi tal IF measured by logic analyz-er and  V SA sof tware.

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for applications that require customiza-tion of standardized technology for appli-cations such as secure SDR military radio.

It can also be useful to bring the HDLcode into design simulation for direct comparison to the simulated test vectorreferences in the design simulation envi-ronment. An example is shown in Figure2, where HDL co-simulation is used to

directly compare vectors with the simu-lated model.

Debugging with Vector Signal AnalysisPerforming VSA modulation domain

analysis on the digital I/Q or digital IFprovides an additional level of FPGA design verification in addition to com-paring test vectors of the baseband cod-

ing/decoding stages. To illustrate this,let’s examine a case study.

 An LTE I/Q modulator design isimplemented on an FPGA development board as shown in Figure 3. The FPGA board includes a DAC, to convert theFPGA output to an analog output. A real-time oscilloscope with VSA softwareis used to probe the analog IF signal at 

the output of the DAC, as shown in theleft side of Figure 3. In addition, a logicanalyzer with VSA software is used tosimultaneously probe the digital IF sig-nal at the input of the DAC, as shown inthe right side of Figure 3.

 A close-up view of the VSA modula-tion domain measurements, performed

 with the logic analyzer probing the dig-ital IF and oscilloscope probing theDAC output, reveal degraded waveformquality and EVM performance of approximately 7.2%. Waveform distor-

tion can also be observed with the dis-persion shown in the measured constel-lations on the upper left of the VSA dis-plays. Since the digital IF from theFPGA output (input to DAC) and theDAC output reveal the same EVMresult, the issue is resulting from anissue in the FPGA implementation andnot from the digital-to-analog conver-sion with the DAC.

The challenge now is how to figure out the source of the error in the FPGA I/Q modulator implementation. Possibly,there is an issue with the digital upcon-

 verter (digital IF) from within the FPGA,or an issue with the digital I and Q pathsor FIR filtering. How can the source of error be pinpointed?

To debug the FPGA implementation,test points are placed within the XilinxFPGA by using the Xilinx ChipScopePro Core Inserter. One option in that tool is the insertion of a Trace Core 2 nd

(ATC2). With such a measurement core,designated signals get assigned to“Signal Banks” through the use of a mul-tiplexor and FPGA routing created

inside the FPGA. Then selected signalsare routed out to the FPGA I/O and ulti-mately to a connection point for a logicanalyzer. Now deep capture traces canbe taken on the signals.

The FPGA Dynamic Probe applicationcan be used to select the measurement bank associated with the filtered I and Q data. The MUX is switched within theFPGA to access those signals, the logicanalyzer captures those signals, and the

 VSA software processes them. The VSA constellation diagram shows significant 

dispersion that is contributing to an EVM5.1%. The spectrum also looks incorrect.

40  www.defensetechbriefs.com Defense Tech Briefs, February 2013

Figure 4. Close-up of logic analyzer  V SA measuremen t (lef t) at FPGA digi tal IF and Infiniium oscilloscopemeasuremen t (righ t) at DAC ou t pu t. Bot h showed degraded wa veform quali t  y and E VM of 7.2%.

Figure 5. Probing at fil tered I and Q ou t pu t s wi t hin t he FPGA implemen tat ion.

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Defense Tech Briefs, February 2013  www.defensetechbriefs.com

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Figure 6. Probing at fil tered I and Q ou t pu t s wi t hin t he FPGA implemen tat ion af ter correct ing t he FIR tap coefficien t.

Upon closer inspection of the individ-

ual filtered I and Q data signals (right side of Figure 5), we can see a differencein the overall shape of each signal.Notice that the I data, displayed in a“chart” mode (which converts digitaldata to displayed time domain wave-form), has some higher frequency dis-tortion present, yet the Q data does not have this distortion. A closer examina-tion of the HDL code revealed a tapcoefficient sign inversion on the I FIR.The FIR tap coefficient was corrected,and the FPGA design was recompiled.

Figure 6 shows the new measurement results with the I FIR tap coefficient cor-rected. The resulting constellation isnoticeably cleaner, and EVM is now 0.5%. The spectrum no longer hasimages, and the I data on the right of Figure 6 no longer shows the distortionpreviously observed in Figure 5.

The VSA software also works with RFsignal analyzers, so this debug methodol-ogy could be extended to the output of an SDR’s RF transmitter output to debugissues at RF, IF, and analog I/Q using anoscilloscope, or probing within an FPGA 

implementation, as shown in this exam-ple.

SummaryThis article discussed an improved

methodology to verify FPGA implemen-tations for complex OFDMA waveformssuch as LTE. Simulated commercial LTEreference vectors can be compared withbaseband coding/decoding test vectorsfrom an HDL simulation or by probing

 vectors with a logic analyzer. This canhelp to ensure a consistent interpreta-

tion of the many coding configurationsand modulation configurations (e.g.

QPSK, 16QAM, and 64QAM) supported

by the LTE standard. In addition, theLTE reference vector simulation blockscan be customized for potential SDR applications such as secure military com-munications. Modulation domain analy-sis of the FPGA design can also be per-formed to verify the performance of thedigital I/Q and digital IF stages. Using

 VSA software on a logic analyzer enablesthe FPGA implementation to be probedand debugged at various stages withinthe FPGA implementation, as discussedin the case study. Furthermore, using thesame VSA software in design simulationsoftware, oscilloscopes, and RF signalanalyzers enables the system engineer toprobe along the SDR’s analog basebandand RF chains (analog I/Q, IF, or RF),both in the design and test phases, toquickly identify and resolve potentialissues.

This article was written by Greg Jue,Applications Development Engineer/Scientist,and Brad Frieden, Product Planner for the 

 Digital Debug Solutions (DDS) product line at Agilent Technologies, Santa Clara, CA. For more information, visit  http://info.hotims.

com/45600-541.

References

[1] “Enabling Secure Communications inMilitary 4G LTE Environments”,http://eecatalog.com/4g/2011/11/03/enabling-secure-communications-in-military-4g-lte-environments/

[2] “Funding Emergency Communications:Technology and Policy Considerations,”http://www.fas.org/sgp/crs/homesec/R41842.pdf 

[3] Video: “FPGA Design with SystemVueLTE,” http://www.youtube.com/watch?v=Pl0XFWqmTGY 

[4] Video: “LTE IQ Mo dulator System:Debug and Validation,” http://www.

 youtube.com/watch?v=QuhfjR6c6tw 

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GORE® Electronic Materials

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 www.defensetechbriefs.com Defense Tech Briefs, February 2013Free Info at http://info.hotims.com/45600-811

Figure 1. Modeling and simulation using Remcom’sXFdtd to assess performance of on-platform anten-

nas and impact of planned modifications in-theater:(a) antenna radiation in free space (no vehicle); (b)

(a)

(c)

Simulation Optimizes Safety andPerformance When Integrating an

 Antenna Onto a Platform

Successful integration of an antennaonto a vehicle platform poses many 

challenges. Vehicle features impact anten-na performance by blocking, reflecting,or reradiating energy, and co-site interfer-ence can impair the effectiveness of multi-antenna configurations. Platform motionand environmental factors such as terrainand buildings may reduce system effec-tiveness in actual operational conditions.Furthermore, radiation hazards may poserisks to nearby personnel. Modeling and

simulation provides a powerful tool to aidin understanding these issues and devel-oping solutions.

The key benefit of simulation-basedassessment is that it is relatively fast andcost-effective compared to physical sys-tem modification and measurement.Modeling and simulation can assessoptions and tradeoffs in order to select asmall number of planned approaches well before any physical testing occurs; asa result, experimental design focuses on

 verifying planned approaches and fine-tuning alternatives demonstrated to beeffective in simulations.

In addition, a number of challengesarise when attempting to performexhaustive laboratory or field testing onan integrated system:

• Available measurement facilities may not be able to accommodate largerplatforms.

• Facilities may not be able to handle thefull range of frequencies for the sys-tem(s) under test.

• Comprehensive in situ measurementsmay be difficult or impractical foroperational conditions (e.g., aircraft inflight or a HMMWV in an urban envi-ronment).

• In-theater modifications could require

additional testing. A comprehensive modeling and simu-

lation toolset allows an organization toovercome these challenges by being ableto simulate any number of conditions,identify and resolve key issues, andreserve the use of physical measurementsto confirm successful pre-test, simulation-based assessments.

 Assessing PerformanceHigh-fidelity electromagnetic solvers

predict the performance of an antenna,including effects introduced by the fea-tures of a vehicle on which it is mounted.Figure 1 shows a series of results from sim-ulations that were performed by the U.S.

 Army Communications-Electronics Re-search, Development, and Engineering

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GORE® Wire and Cable

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Defense Tech Briefs, February 2013  www.defensetechbriefs.com Free Info at http://info.hotims.com/45600-812

Center (CERDEC) using Remcom’sXFdtd® software and an in-house ray-trac-ing tool. Figure 1(a) depicts the radiationpattern simulated in free space without 

any vehicle or other obstruction to per-turb the pattern; Figure 1(b) shows theradiation pattern once the antenna hasbeen mounted on a vehicle. Although thepattern has clearly changed, adding somesignificant back lobes and causing varia-tion in the forward radiation pattern, theantenna exhibits similar forward radia-tion and gain to the original design. Thistype of simulation can be performed toevaluate any number of potential alterna-tive configurations until a successfuloption is identified and selected for thefinal integration.

Figures 1(c) and 1(d) illustrate how in-theater modifications complicate antennaperformance. Figure 1(c) displays the pat-tern after modifying the vehicle with theaddition of an Overhead Wire Mitigationkit (OWM) using a metallic post. (Note:OWM prevents overhead obstructionssuch as clotheslines, power lines, andfoliage from damaging installed anten-nas.) The impact is significant. A nullforms in the main lobe, reducing antennagain forward of the vehicle. Replacing themetal post with a fiberglass rod, as shown

in Figure 1(d), significantly improves per-formance with the return of strong gain inthe forward direction.

 At higher frequencies, platforms may become electrically large, where electri-cal size describes the size of an object relative to the wavelength of a signal.Modeling an electrically large scenariousing a full-wave solution such as theFinite Difference Time Domain (FDTD)method employed in XFdtd couldrequire more memory or longer simula-tion times than desired, and a two-step

hybrid approach may provide a more viable alternative.

Figure 2 demonstrates the simulationof an X-Band antenna array mounted ona Global Hawk. The full-wave methodfrom XFdtd determines the radiation

pattern of the array on a metal groundplane. A solution based on the UniformTheory of Diffraction (UTD) fromRemcom’s XGtd ® solver then calculatesthe radiation pattern resulting frommounting the array to the underside of the electrically large Global Hawk. Thistwo-step process provides an accurateand efficient assessment of the overallperformance of the antenna in its oper-ational configuration.

Co-Site InterferenceMilitary vehicles commonly incorpo-

rate several antenna systems in closeproximity. Interference between thesesystems can cause problems with simulta-neous operation. As a first step in under-standing the impact, the power couplingbetween each transmitting and receivingantenna must be assessed. This is typical-ly done by simulating or measuring thepower received at each installed antennafrom every transmitting antenna. In thecase of arrays, these transmitted andreceived powers must be summed appro-priately in order to represent the real sig-

nals observed at the array’s input port.The ratio of received power to the trans-mitted power of the radiating system rep-resents power coupling and describeshow much of the transmitted power, in-band or out-of-band, propagates into theneighboring system.

This type of investigation helps ana-lysts determine whether or not a trans-mitter affects the operation of neighbor-ing systems and develop mitigationstrategies if required. Examples of miti-gation might include:

• Careful selection of frequency bandsto avoid conflict.

Figure 2. Hybrid approach using XFdtd and XGtd to sim-ulate antenna radiation from an antenna mounted on aGlobal Hawk: (a) antenna array on ground plane(XFdtd); (b) array mounted on Global Hawk (XGtd).

(a)

(b)

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44 Defense Tech Briefs, February 2013Free Info at http://info.hotims.com/45600-813

• Repositioning of antennas to reducethe impact.

• Alternating use of systems (essentially time division multiplexing) so that anten-nas are not operating simultaneously.

• Modification of system front-end filtersto allow simultaneous operation (inextreme cases).Simulation results assist with all of 

these approaches by enabling rapid con-

sideration of alternative antenna configu-rations. Once pre-test modeling and sim-ulation assessments are completed, meas-urements efficiently focus on confirminganalyses and mitigation approaches.

Impact of the Environment The environment plays an important 

role in antenna performance. The pres-

ence of a dielectric ground plane in thenear field of the antenna will alter radi-ation performance. As fields propagateto the far zone, interactions with theground and structures cause interfer-ence due to multipath, which leads toconstructive or destructive interferenceand shadowing. Nowhere is this inter-ference more evident than in denseurban scenarios, where the specific lay-

outs of buildings can become the singlemost dominant factor in the propaga-tion of fields within the environment.

The multipath effects of buildings inan urban environment for two differ-ent scenarios were modeled withinRemcom’s Wireless InSite® suite. At afundamental level, consideration of theintended environment, such as assessing

how ground beneath a vehicle impactsthe effective range of a system, may alsobe used during integration to ensurethat a system is able to perform its in-tended mission.

Potential Radiation Hazards ANSI standards, DOD Instruction

6055.11, and numerous other govern-

ment standards provide regulatory spec-ifications for maximum permissibleexposure (MPE) to protect personnelfrom radio frequency (RF) radiation.

 When alternative systems and locationsfor mounting system antennas are beingconsidered, one key factor must includeconsideration of the potential risk of radiation exposure to personnel. Figure4 displays the magnitude of the electricfields that XFdtd predicts will enter thecabin of a HMMWV, mostly through its

 windows, from an antenna mounted on

the roof. Information about electric andmagnetic field strengths, frequency,duration, and duty factor of systemtransmissions combine in a relatively straightforward manner to determine

 whether the system is likely to exceedthe MPE. At a more detailed level, it isalso possible to use the FDTD method toestimate specific absorption rate (SAR)for a person modeled as sitting withinthe vehicle or standing nearby; however,field levels over time (see figure) are theusual metric for a radiation hazardassessment within the DOD.

ConclusionThere are a number of critical issues

to consider when integrating an anten-na onto a vehicle platform, particularly 

 when the intended use is for military operations. These include assessment of the impact of vehicle features on radia-tion, co-site interference from multi-antenna systems, and environmentalobstructions to propagation, as well asanalysis of potential radiation hazards.

 A variety of electromagnetic modeling

solutions exists for analyzing variousparts of the problem, and there aremany cases where hybrid approachesusing multiple solutions greatly assist inthe overall understanding of the issues.By using these tools for simulation-based assessment prior to final antennaintegration and laboratory or field test-ing, an organization can identify key issues and develop mitigation approach-es cost effectively.

This article was contributed by Remcom,State College, PA. For more information, visit 

http://info.hotims.com/45600-542 .

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What’s On 

Featured Sponsor Video: Helical Antenna SimulationUsing the pre-loaded scripting library in XFdtd, this video demonstrates simulationof a helical antenna, which is then imported into XGtd for analysis on a satellite. Seehow XFdtd's scripting language helps to quickly automate advanced modeling tasks.

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46  www.defensetechbriefs.com Defense Tech Briefs, February 2013

Ro ta ting De tona tion-Wa v e EnginesRo ta ting de tona tion engines ha v e the po tential to increase the performance of air-brea thing propulsion de vices.

Naval Research Laboratory, Washington, DC 

 All Navy aircraft and missiles use gas-turbine engines for propulsion.

Many ships are also dependent on gas-turbine engines to generate bothpropulsive power and electricity. Theseengines are fundamentally similar toengines used to power commercial air-planes. Future ships moving to an “all

electric” paradigm for the propulsionsystem will still require these gas-turbineengines to generate electricity for thepropulsion system and also for othercritical onboard systems. Because of theamount of power required by modern

 warfighting ships, and the prospect that this power requirement will only increase, there is a strong interest inimproving the specific fuel consumptionof these engines.

Gas-turbine engines are attractivebecause they scale nicely to large pow-

ers, are relatively small and self-con-tained, and are relatively easy to main-tain. Current gas turbines are based onthe Brayton thermodynamic cycle, in

 which air is compressed and mixed withfuel, combusted at a constant pressure,and expanded to do work for either gen-erating electricity or for propulsion.

To make significant improvements tothe performance of gas-turbine engines,different and possibly more innovativecycles must be investigated, rather thanthe Brayton cycle. An attractive possibili-ty is to use the detonation cycle insteadof the Brayton cycle for powering a gasturbine. NRL has been a major player inthe development of pulse detonationengines (PDEs). The rotating detona-tion engine (RDE) is a different strategy for using the detonation cycle forobtaining better fuel efficiency. Like

PDEs, RDEs have the potential to be adisruptive technology that can signifi-cantly alter the fuel efficiency of shipsand planes; however, there are severalchallenges that must be overcomebefore their benefits are realized.Research over the last several decadeson materials that are able to withstand

the high pressures, temperatures, andheat fluxes associated with detonations,and on initiators that are efficient, fast,and reliable, have made detonationengines a possibility.

 A Brayton cycle relies on a multistagecompressor in order to increase the pres-sure of the air from atmospheric to a high-er pressure. Without this compression, no

 work can be obtained from the gas-turbineengine. Typical compressor ratios vary from 10 to 30 and are easily the most com-plex machinery in a gas-turbine engine.

Example of a Rotating Detonation Engine (RDE, left), and simulation of the combustion chamber (right) for an RDE.

Injection and mixing

Thrust vector& associatedmoments

Successivedetonation wavesself-ignition process

Stability Domain

Generated acousticenvironment

Non-symmetricfeeding propagation(chamber & nozzle)

Jet direction andswirl effect

Mechanical behaviorof cooled structure(high frequency shocks)

Thermal behaviorcooled structure

Generated vibrationenvironment

Skin frictionforces

Nozzle-End

Head-End

Micro-nozzles

Detonation

Wave

Y

X

Technology Focus:Power Management

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Defense Tech Briefs, February 2013 47Free Info at http://info.hotims.com/45600-815

Detonations, on the other hand, are close to a constant volumereaction process, and naturally generate high pressures that canthen be expanded to do work without any compressor at all.

The rotating detonation engine takes a different approachtoward realizing the efficiency of the detonation cycle. By allowing the detonation to propagate azimuthally around anannular combustion chamber, the kinetic energy of the inflow can be held to a relatively low value, and thus the RDE can usemost of the compression for gains in efficiency, while the flow 

field matches the steady detonation cycle closely. A schematic of a rotating detonation engine is shown in the

figure. Current basic studies done at the NRL are focused on amuch simpler annular combustion chamber. The combustionchamber is an annular ring in which the mean direction of flow is from the injection end to the exit plane. A series of micro-noz-zle injectors flows in a pre-mixture of fuel and air or oxygen axi-ally from a high-pressure plenum, and a detonation propagatescircumferentially around the combustion chamber, consumingthe freshly injected mixture. The gas then expands azimuthally and axially, and can be either subsonic or supersonic (or both),depending on the back pressure at the outlet plane.

Rotating detonation engines, a form of continuous detonation-

 wave engine, are shown to have the potential to further increasethe performance of air-breathing propulsion devices above pulsedor intermittent detonation-wave engines. Simulation of pulse det-onation engines shows many of the significant flow-field featuresof RDEs, and explains how the performance of these enginesrelates to the ideal thermodynamic detonation cycle.

This work was done by Douglas Schwer and Kazhidathra Kailasanath of the Naval Research Laboratory. For more information, download the Technical Support Package (free white paper) at www.defensetechbriefs.com/tsp under the Mechanics/Machinery category. NRL-0060 

Bi-Axial  Vibra tion Energ y Harv estingThis  technique can be used  to captureairframe  vibra tional energ y , and conv ertit into elec trical power.

Defence Science and Technology Organisation,Victoria, Australia 

For air platforms, the installation of Structural HealthMonitoring (SHM) systems is complicated by the fact that the

majority of SHM devices need to be fitted on internal aircraft 

structure, underneath the aircraft’s skin. If the SHM device is ina location that is difficult to access, then powering the device may be problematic because traditional powering methods are gener-ally not feasible. For example, replacing batteries on many SHMdevices deployed across a fleet would be impractical, and access-ing an onboard power system to supply SHM devices may lead toflight worthiness and certification issues.

To address this powering issue, the use of vibration energy harvest-ing (VEH) has been investigated. Two unresolved scientific issuesthat inhibit the use of VEH on aircraft are: (1) the need for a wideoperational frequency bandwidth to permit harvesting from the fre-quency-rich vibration that can be present on airframes, and (2) theneed for a multi-axial harvesting approach, since aircraft vibrations

are typically not uni-axial. Previous work addressed the first issue by developing the vibro-impacting energy harvesting approach that 

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48 Defense Tech Briefs, February 2013Free Info at http://info.hotims.com/45600-814

Power Management

produced VEH over a broader operationalbandwidth compared with many other har-

 vester approaches, including harvesters that are currently commercially available.

The second fundamental issue withmost VEH approaches (again, including

all known commercial vibration energy harvesters) is that they are uni-direction-al, and hence can only harvest vibra-tional energy from host accelerationsalong a single axis. Therefore, while aconsiderable amount of scientific litera-

ture exists on the topic of VEH, none todate reports on a technique to effectively harvest from bi-axial host accelerations.

 A bi-axial approach represents a sig-nificant advancement in VEH; specifical-ly, the approach increases the opera-tional directionality from single-axis to360 degrees in a plane. Furthermore,this design uses a magnet/bearing can-

tilever analogue (replacing the can-tilever design used by many harvesters),potentially allowing a significant reduc-tion in harvester volume. This designalso uses an oscillating ball bearing tocreate magnetic flux steerage through amagnetoelectric laminate transducer togenerate harvestable electrical power.

The concept involves three main com-ponents: (1) a sensor mounted insidethe aircraft at a difficult-to-access loca-tion is monitoring in-flight mechanicalloads on an airframe, (2) with the sensor

utilizing energy that is parasitically har- vested from local airframe vibrations by an energy harvester, (3) when the air-craft is on the ground, a wireless link—the acoustic electric feedthrough—isused to download sensor data and simul-taneously provide additional energy tothe sensor unit.

The bi-axial vibration energy harvest-ing approach can harvest energy fromthe multi-axis accelerations experiencedby an aircraft. A bi-axial oscillator wascreated using a permanent-magnet/ball-bearing arrangement. The magnet pro-duces a bi-axial restoring force on thebearing, and as the bearing oscillates, it steers magnetic field through a magne-tostrictive/piezoelectric laminate trans-ducer, thereby producing an oscillatingcharge that can be harvested.

Modeling was used to make a qualitativeassessment of the magnetic flux changesin the ME transducer as the bearing oscil-lates, which indicated that large flux varia-tions occur as the bearing moves from themagnet’s central-line towards the edge. A simple laboratory demonstrator of a bi-

axial ME energy harvester was createdusing a Terfenol-D/lead zirconatetitanate/Terfenol-D transducer. Harvesteroutput was measured as a function of drive-angle, host acceleration, and loadresistance. The harvester produced a peakrms power of 121 mW from an rms host acceleration of 61 mG at 9.8 Hz.

This work was done by Scott Moss, Joshua McLeod, Ian Powlesland, and Steve Galea of the  Defence Science and Technology Organisation.For more information, download the Technical Support Package (free white paper) at 

www.defensetechbriefs.com/tsp under the Physical Sciences category. DSTO-0002 

Registration is open on January 1st with a $500discount between January 1 and March 30th, 2013.

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Sensor EnergyHarvester

Acoustic-ElectricFeedthrough

HandheldInterrogator

Sensing Points

External 

 Airframe Interior 

 Aircraft Skin(Composite or Metallic)

Power  Data

AEFCMPLE

A schematic of a wireless structural health monitoring system concept with the sensing unit, Energ y Harv ester, and wireless data and power transfer capability.

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Defense Tech Briefs, February 2013 49Free Info at http://info.hotims.com/45600-817

Free Info at http://info.hotims.com/45600-816

Elec trochemical Energ y Storage Ma terials

 Applica tions include small, autonomously powered, remo tely  pilo ted aircraft;airfield support; deplo y ed airbase power;

and portable soldier power.Air Force Research Laboratory, Wright- Patterson Air Force Base, Ohio 

One of the most important requirements in next-generation bat-teries is to concurrently deliver high energy density and high

power density (fast charge-discharge rates). The high power densi-ty requirement can be met with enhanced ion and electron trans-port kinetics in batteries, which in turn requires active materials with high ion diffusion constants and conductive additives or archi-tectures for faster electron transport to respective current collec-tors. It is well known that nanostructuring the electrode materials would significantly enhance the characteristic time constant for ion

diffusion, thereby reducing the intercalation/deintercalation time.However, nanostructuring electrode materials leads to some

issues such as reduced electron transport kinetics throughinterparticle boundaries, and undesired side reactions due tohigh electrode/electrolyte surface area. In nanostructured elec-trode materials studies, three-dimensional (3D) conductingnano-architectured current collectors were chosen (e.g., elec-trodeposited Ni nanowire arrays), and they were coated withultrathin conformal layers of active materials to circumvent thereduced electron transport kinetics issue. To get around theside reactions due to high electrode/electrolyte surface area,active materials and electrolytes may be suitably chosen that areleast reactive, such as TiO2, which is not known to form a solid

electrolyte interphase (SEI). Atomic layer deposition (ALD) was chosen as a process to

conformally coat the 3D current collector nano-architecture with nanometer-scale control over active layer thickness. Thusthe Li-ion diffusion in active electrode material is limited to acouple of nanometers, and electron conducting current collec-tor is in contact with the ultrathin active layer everywhere. Such3D designs can achieve the ultimate goal of 3D all-solid-statemicrobatteries by sequentially assembling an anode (cathode)layer followed by a solid electrolyte/separator, and then thecomplementary cathode (anode) filling the space in betweenthe nanowires. All-solid-state 3D microbatteries will be crucial tosuccessful operation of many miniaturized autonomous devices with significant interest to future Air Force needs.

Despite the fact that nanostructuring of battery electrodescan increase battery power density, the 2D planar design fun-damentally limits the amount of energy that can be stored andpower that can be delivered per unit area, mass, and volume.The 3D battery architectures exploit the advantages of nano-structuring, while potentially decreasing the areal footprint of a 2D design. In this task, a variety of potential 3D designs waspursued that are generally composed of a 3D matrix of theelectrodes (periodic or aperiodic) in order to maximize thenumber of interfaces and thus interfacial reactions in the bat-tery. Although transport between the electrodes remains 1D,the additional interfaces that are interpenetrated in the 3Dnetwork offer major gains in the areal footprint, while the 3D

design minimizes transport distances between and in the elec-trodes, which can result in higher power densities.

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50 Defense Tech Briefs, February 2013Free Info at http://info.hotims.com/45600-818

Power Management

1.00.0 100 200 300 400 500

1.5

2.0

2.5

3.0

1E-3

0.01

0.1

1

Capacity (mAh/g)

   E   (   V   )

20th

discharge

1st

discharge

ChargeDischarge

1st

charge

20th

charge

0 10 20Cycle number

   A  r  e  a   l   C  a  p  a  c   i   t  y

   (  m   A   h   /  c  m

   2   )

Charging

Discharging

3D

2D

A B

(A) Charge-discharge profiles of ALD TiO2 layer coated Ni Nanowire Electrodes annealed at 450 °C in Argon for 2 hours. (B) Comparative areal capacity of3D TiO2 coated Ni nanowires and 2D TiO2 film electrodes.

The fabrication and processing method-ologies for battery electrodes are beingdeveloped that can be implemented tocoat 3D architectures with micron andnanosized features. Atomic layer deposi-tion (ALD) is a gas phase, self-limiting

growth technique that allows for uniform,conformal growth of thin films on 3Dstructures using sequential surface reac-tions. A low-temperature ALD (LT-ALD)process was developed in order to deposit conformal and uniform films of amor-

phous SnOx on CNTs, as well as a high-temperature (HT-ALD) process to deposit nanoparticles of Sn and SnO.Morphological and electrochemical analy-ses were conducted to provide a detailedunderstanding of the complex architec-ture of the hybrid electrodes and how thisrelates to their device performance.

The capability to create distinctly dif-ferent forms of the hybrid SnOx–carbonanode material was demonstrated—either nanoparticles attached directly tothe carbon nanotubes or as a conformalcoating. The measured specific capaci-ties of the SnOx-buckypaper compositesare quite high and are considerably higher than graphite itself. Importantly,for small particle sizes, the specificcapacity was shown to be greater thanthe theoretical capacity for Sn (Li4.4Sn,993 mAh/g), which suggests that nano-sized particles of Sn have a larger solidsolution range with lithium than bulk Snparticles. This observation could have

important implications for designingeven higher-energy-density systems.

This work was done by Michael F. Durstock,Benji Maruyama, and Patrick S. Carlin of the Air Force Research Laboratory; Gyanaranjan Pattanaik, Jacob M. Haag, Daylond Hooper,and Gordon Sargent of UES Inc.; Placidus Amama and Neal A. Pierce of the University of 

 Dayton Research Institute; Rahul Rao of the National Research Council; and Kent Weaver of SOCHE Inc. For more information, download the Technical Support Package (free white  paper) at www.defensetechbriefs.com/tsp 

under the Materials & Coatings category.AFRL-0220 

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Defense Tech Briefs, February 2013 51

The brightest minds in Aerospace and Defense havebeen selected as Keynote Speakers for AeroDefManufacturing 2013.

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Q uantita tiv e Analysis of a Hybrid Elec tric Humv ee forFuel Economy  Impro v ementHybrid  v ehicle powertrains show impro v ed fuel economy gains due  to optimizedengine opera tion and regenera tiv e braking.

Army RDECOM-TARDEC, Warren, Michigan 

The Army has acquired several hybridplatforms to assess the applicability of 

hybrid technology for military missions.These hybrid platforms include both seriesand parallel hybrid topologies. This workcompares a conventional HMMWV (HighMobility Multi-purpose Wheeled Vehicle)M1113 with a series hybrid HMMWV XM1124 in terms of fuel economy improve-ments over three military drive cycles.

The attributes of the hybrid powertrainthat help improve fuel economy of theirconventional counterparts are more effi-

cient engine operation and regenerativebraking. In a series hybrid topology, theengine operation is decoupled from the vehicle road load. In the XM1124, the bat-tery system is charged by the PowerGeneration Unit (PGU) (engine-genera-tor) and by regenerative braking. The PGUcan potentially be operated at higher effi-ciency, producing more power than what is

required at the wheels, since the battery pack can absorb the difference betweenPGU power and road load power, withinthe limits of its allowable state of charge.

Three drive cycles were analyzed for fueleconomy comparisons between the con-

 ventional HMMWV M1113 and the serieshybrid XM1124. The HMMWV M1113 isequipped with a 6.5-L V8 turbo-chargeddiesel engine, a four-speed automatic trans-mission, and has a gross weight of 5216 kg.The XM1124 is a series-hybrid version of the M1113 with a PGU consisting of a 4-

cylinder 100-kW diesel engine, coupled toa 100-kW PM brushless generator. Theelectric traction is provided by two 100-kW PM brushless motors. The XM1124 utilizesa 100-kW Li-Ion battery pack.

The fuel economy comparisons arebased on HEVEA (Hybrid Electric VehicleExperimentation and Assessment) datacollected for both the XM1124 and the

M1113 vehicles over the three drive cycles.In addition, only HEVEA data was analyzedthat resulted in SOC (State of Charge)equalization, i.e. the battery SOC is equalat the beginning and end of the test cycle.The HEVEA data collected was comprisedof time versus vehicle speed, front and rearmotor current, generator current, battery current, battery pack voltage, battery packSOC, fuel rate, and engine speed. The fueleconomy was calculated from the fuel rateand vehicle speed.

The engine operation efficiency was

analyzed by superimposing the engineoperating speed-torque points over theengine efficiency map (which shows thespeed-torque characteristics at different efficiencies of the engine). The XM1124engine was shown to be more efficient than the older M1113 engine.

The engine torque was not directly measured during the HEVEA tests, since

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52 Defense Tech Briefs, February 2013Free Info at http://info.hotims.com/45600-821

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Bellows assembliesto balance cabinpressure

Pressure responsivebellows assembly tosense altitude and

air speedBellows seal inastronautsbreathing regulators

Flexible bellows asas waveguide incommunicationsystems

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Bellows assembliesin hydrogensystem control

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Designing with less time,money and resources ismore challenging than ever before but not impossible.

Power Management

A schematic of the XM1124 Series Hybrid  V ehicle. It consists of a 4-cylinder, 100-kW Peugeot diesel engine, coupled to a 100-kW PM brush-less generator from UQM.

this was not available on the CAN (Controller Area Network)

data bus for either the XM1124 or the M1113. As a result, theengine torque was derived from the other available data. In thecase of the XM1124, generator electrical current, enginespeed, and battery voltage were recorded. In the case of theM1113, the engine torque was known fuel map (engine speedand torque vs. fuel rate) and measured instantaneous fuel rate.The engine speed of the XM1124 is constrained over a narrow speed range, whereas the conventional M1113 engine speed iscoupled to the vehicle speed.

The contribution of regenerative braking on overall fueleconomy was determined from analyzing the braking events of the HEVEA test data for the XM1124. Once the braking events were identified, the total regenerative braking energy was com-puted. The total regenerative braking energy was converted toan equivalent fuel consumption using the minimum brake spe-cific fuel consumption (BSFC) of the engine (220 g/kWh).This equivalent fuel consumption was added to the recordedfuel consumption for the cycle, and a new fuel economy was cal-culated. This new fuel economy represents the estimated fueleconomy of the vehicle if regenerative braking was disabled.

The regenerative braking plays a very small role in the fueleconomy improvements of the XM1124 over the M1113. Themain reason for this is that the regenerative braking of theXM1124 is restricted to 10% of its full potential. As a result,most of the available braking energy is lost in the frictionbrakes of the XM1124. It can be concluded that the fuel econ-omy benefits of the XM1124 over the M1113 are due to more

efficient engine operation of the series hybrid powertrain overthe conventional powertrain.

The analysis of the HEVEA data revealed that the hybridXM1124 does not always produce better fuel economy than theconventional M1113. Factors that adversely affected fuel econo-my of the XM1124 include low vehicle speeds (<10 mph), result-ing in the engine operating at lower efficiency; wet and cold roadconditions, which affected fuel economy; and excessive chargingof the battery using the PGU, resulting in an overall lower effi-ciency from fuel tank to wheel.

This work was done by Ashok Nedungadi and Robert Smith of Southwest Research Institute, and Abul Masrur of Army RDECOM- TARDEC. For more information, download the Technical Support 

Package (free white paper) at www.defensetechbriefs.com/tsp under the Physical Sciences category. ARL-0150 

8.76:1 8.76:1

8.76:18.76:1

Engine

100 kW

Generator

Vehicle Battery

DC/DC

100/85 kW

141 kW/18.6 kWh

Li-Ion Saft Battery Rear Motor

Front Motor

Mechanical PathElectrical Path

100/55 kW

100/55 kW

Front inverter(DC to 3 phase)

Rear inverter(DC to 3 phase)

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Technologies of Tomorrow Ideas and InspirationThought LeadersIndustry Peers

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54  www.defensetechbriefs.com Defense Tech Briefs, February 2013

NEW PRODUCTS

Power Supply The VPXtra™ 1000CD power supply from

Behlman Electronics (Hauppauge, NY) delivers up to1000 Watts of clean, regulated 12 VDC power and 3.3

 VDC auxiliary power. VPXtra 1000CD is OpenVPX Vita 62 compliant. Standard features include overvoltage; short circuit and thermal protection;and no minimum load requirement. The 12 VDC output can be paralleled for higher powerand fail-safe redundancy.

For Free Info  Visit http://info.hotims.com/45600-515

DSC USB CalibrationSystem

Morehouse (York, PA) hasintroduced a new DSC USB sys-tem with mini-net-book (load celland case not included) forthe calibra-

tion of load cells,testing machines,and other force or torquesystems. The new system is direct readingaccording to ASTM-E74 and E2428, and fully USB powered, eliminating excess power cables. ASTM Class A lower limits are better than 2% when paired with Morehouse ultra-precisionload cells. The system’s program is designed touse the coefficients from a calibration report 

and apply them to the “live” signal of the DSCunit, thereby eliminating the need for loadtables. The end-user can read direct engineeringunits in LBF, KGF and Newtons.

For Free Info  Visit

http://info.hotims.com/45600-516

3U Power Supply Dawn VME Products (Fremont, CA) offers the PSC-6236 uni-

 versal AC-input, VITA-62-compliant, 6-channel 3U OpenVPXpower supply, with up to 400 watts output for air or conduction-cooled systems. The power supply defines connector configura-

tion, power generation requirements, utility, functionality, andform factor needs for power modules mating to a VPX backplanepower supply slot. Input range is 85-264 VAC, 47-400 Hz.

The PSC-6236 offers current sharing with up to four power sup-plies for outputs of 12V, 5V, and 3.3V. The power supply is designed to be compliant with MIL-STD-461, MIL-STD-704F, and MIL-STD-810F. Dawn's proprietary embedded RuSH™ Rugged SystemHealth Monitor technology actively measures voltage, current, and temperature on each rail.

The PSC-6236 is interfaced to the Intelligent Platform Management Bus (IPMB), providing an I2Ccommunication link with system cards. Onboard microprocessor and firmware offer real-time over

 voltage, over current, and over temperature protective control, with factory programmable powersequencing and shutdown for all voltage rails. Firmware enables additional PSC-6236 features,including customer-specified monitoring windows for power sequencing, special alerts, alarms, andstatus reports. An optional 3-axis accelerometer records and time-stamps shock, vibration, and othercritical events. The PSC-6236 front I/O panel includes an LED status indicator, a USB port for field

firmware upgrades, and VBAT battery access for support of the VPX memory backup power bus.For Free Info  Visit http://info.hotims.com/45600-510

Test Integration ASSET® InterTech (Richardson, TX) and Teradyne (North

Reading, MA) have integrated the JTAG and boundary-scan test capabilities of ASSET's ScanWorks® platform into Teradyne'sPXI Express-based High Speed Subsystem (HSSub). The inte-gration provides support for custom and standardized high-speed digital buses in new or legacy test systems.

ScanWorks was integrated through Teradyne's Boundary ScanRuntime Library (TERBSR), a software facility that offers instrument 

access through an application programming interface. The ScanWorks boundary-scan and JTAG tools

are now able to test a circuit board through the communications channels on a Teradyne instrument.The channels connect ScanWorks to the high-speed boundary-scan Test Access Port  on the circuit board that is being tested.

For Free Info  Visit http://info.hotims.com/45600-511

D/ A  Conv erter ModulePentek (Upper Saddle River, NJ) has

released a D/A converter module for RFand IF waveform playback, the Cobalt ® Model 71671.The module delivers four independent analogoutputs,each throughits owndigitalupconvert-

er and 16-bit D/A with sampling rates to 1.25GHz. An onboard Xilinx Virtex-6 FPGA pro-

 vides turnkey waveform generation for output signal bandwidths from less than 1 kHz up to250MHz, withan extendedinterpolation rangefrom 2× to 1,048,576×. Users can also cus-tomize the module’s operation by implement-ing their own IP in the FPGA.

The Model 71671 uses two DAC3484 D/A converters from Texas Instruments(Dallas,

TX), each providing two digitalupconverters (DUCs) and

16-bit D/A channels that can translate a quadra-

ture (I+Q) baseband sig-nal to a user-selectable IF(intermediate frequen-cy) center for transmit-ting. Complementary synchronizer productsdeliver clock and timingsignals to multiple 71671modules for synchroniz-ing, triggering, and gat-ing functions. DAC3484

provides a maximum interpolation of 16x, andit accommodates input transmit signal band-

 widths from 250 MHz down to 62.5 MHz.

For Free Info Visithttp://info.hotims.com/45600-512

Separation KernelLynuxWorks (San Jose, CA) has announced LynxSecure support of the VPX3-1256 3U VPX

Intel® Core™ i7 single board computer from Curtiss-Wright Controls Defense Solutions(Ashburn, VA). LynxSecure, a separation kernel and embedded hypervisor, provides a secureenvironment in which multiple guest operating systems and their applications can execute at the same time, in their own virtual partitions.

Curtiss-Wright’s VPX3-1256 combines an Intel® embedded processor, the Intel® Core™ i72nd generation quad-core processor, and a 3U Open VPX board architecture. The SBC

offers two Gigabit Ethernet ports that LynxSecure can assign to different guests.The VPX3-1256 comes with an Intel® Core™ i7 quad-core processor

running at 2.1 GHz and 6MB L3 Cache. The technology, which sup-ports x8 PCI Express Gen 2, also provides up to 16GB of DDR3

SDRAM and built-in Intel® graphics support.For Free Info  Visit http://info.hotims.com/45600-513

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NEW PRODUCTS

LDO  V oltage RegulatorTexas Instruments (TI) (Dallas, TX) has introduced a high-cur-

rent, ultra-low-noise, 1-A TPS7A4700 low dropout (LDO) voltage reg-ulator. The regulator features less than 4.17-uVrms output noise overthe 10-Hz to 100-kHz bandwidth. The TPS7A4700 LDO enables the

setting of any output voltage rail in 100-mV increments. With digital control methods such as I2C or PMBus, the user programsthe output voltage by selecting to either ground or open the binary-

 weighted device pins. For systems where both positive and negative voltage rails are required, theTPS7A4700 can be used together with TI’s -36V/-1A TPS7A3301 LDO linear regulator.

 A wide bandwidth and high power supply rejection (PSR) allow effective filtering of DC/DCswitching supplies running at higher frequencies. 36V input voltage rating enables use in sys-tems running 12V and 24V buses with enough headroom to withstand high-voltage transients.The TPS7A4700 is offered in a 20-pin, 5mm x 5mm QFN package.

For Free Info  Visit http://info.hotims.com/45600-514

Mobile ComputerCognex Corporation (Natick, MA) has made its DataMan® DPM reading technology available

on a mobile computer. The DataMan 9500 industrial-grade mobile computer is ideal for readingchallenging DPM (direct part mark) codes in applications where operators need to view the codedata on an integrated handheld device. The DataMan 9500 provides DPM code reading, direct connectivity to factory networks via Wi-Fi, and an integrated GUI.

The DataMan 9500 features the powerful 2DMax™ algorithm, providing the most advanceddecoding available for difficult to read 2-D codes, including dot peen and laser etched, on any metal

surface. The adjustable focus liquid lens maximizes the depth of field for reading barcodes. This industrially proven technology enables the DataMan 9500 to decode 2-D DPM marks close up, or 1-D barcodes from a distance. The DataMan 9500 connects directly tofactory networks via 802.11 a/b/g protocols on the 2.4GHz and

5GHz bands for real-time wireless communication.For Free Info  Visit http://info.hotims.com/45600-518

16-bit PCIe A /D BoardUltraviewCorporation (Berkeley, CA) has introduced a new16-bit 4-

channel 250MSPS A/D board for very demanding uses such as NMR,RADAR, ultrasound, time-of-flight imaging, spectroscopy, communica-tions systems andantenna testing and other critical applications. Basedon a hardware averaging engine with near-zero dead-time, implement-ed in the board’s XilinxTM FPGA, the ULTRADYNE16-250M×2AVE-8GB-50T/155T and ULTRA-DYNE16-250×4AVE-8GB-50T/155Tcaneachaverage repetitive signal strings up to1 million times withrecord lengths to 16384 samples (-50T model) and 262144-samples (-155T model) uninterruptedly.

The precise repetitive summing of each new string of samples onto a running 32-bit average can betriggered by any one of three software-selectable triggering mechanisms: a TTL input, with selectable–/+ slope,causeswaveformstobeacquired oradded toa running average; software slider-adjustable levelon the incoming signal waveform onany of the 4 channels,with+ or – slope, enabling scope-like trigger-ing,withpre-trigger, ona given placeona repeating waveform; orheterodyningtrigger input, wheretrig-gering will occur on the difference frequency between this input and the sampling clock frequency.

For Free Info Visit http://info.hotims.com/45600-519

Rugged Rackmount 5U GPU Serv er Chassis Plans (San Diego, CA) announced that it will offer the NVIDIA ®

Tesla® K20 GPU Accelerator in its M5U 22A product line. The NVIDIA ®

Tesla® K20 GPU Accelerator can also be integrated into Chassis Plans’ 1Uto 5U rugged rackmount computers when customization is requested.

 With the ability to accommodate up to four (4) of these new K20 GPUcards, the M5U-22A can fulfill demanding information super-computingprocessing needs within a ruggedized short form factor enclosure. Designed to meet /exceed MIL-STD-810G, the M5U-22A ruggedized 5U GPU server will be an asset for in-theater real-time analysis within dataintensive applications such as persistent surveillance, simulation, and radar processing. This military grade computer is able to withstand applications requiring an operational thermal range of 0°C to 50°C.

The dimensions of the M5U-22A are 19” × 8.75” × 22”. The CPU options include a single or dualIntel® Xeon® E5-2658 2.10 GHz (8) Core or single or dual Intel® Xeon® E5-2620 2.00 GHz (6) Core. It has multiple expansion slots: (4×) PCIe(3.0)-X16 (double-width) slots, (2×) PCIe(3.0)-X8 slots, and(1×) PCIe(2.0)-X4 slot.

For Free Info  Visit http://info.hotims.com/45600-520Free Info at http://info.hotims.com/45600-834

Free Info at http://info.hotims.com/45600-835

Free Info at http://info.hotims.com/45600-833

Free Info at http://info.hotims.com/45600-832

Literature & Web Spotlight 

ELECTRICALLYINSULATIVE SNAPCURE EPOXYMaster Bond EP17HT-3 is a sin-gle component epoxy offeringhigh chemical and temperatureresistance while maintainingoutstanding electrical proper-

ties. This high performance adhesive sets up in 20-30seconds and snap cures in only 2-3 minutes at 250-300ºF. EP17HT-3 is capable of curing in sections as

thick as ¼”. www.masterbond.com/tds/ep17ht-3

Master Bond

FREE LI-IONBATTERY WHITEPAPER

Lithium-ion batteries havebecome the most commonbatteries for consumer elec-

tronics, industrial, transporta-tion and power-storage appli-

cations. This paper shows the analysis of complexphenomena such as short circuits, hot-spots or ther-mal runaway. Download your digital copy today at: www.comsol.com/battery 

COMSOL, Inc.

CUSTOM RUBBERMOLDING TO EXACTSPECIFICATIONS

 You probably know us best as pro-ducers of rubber molded parts.However, you may not know that  we’ve produced many parts that 

other companies considered nearly impossible tomake. Our specialty? Precision custom molded partsat a competitive price with on time delivery.Injection, transfer and compression molding of Silicone, Viton, Neoprene, etc. Hawthorne RubberManufacturing Corp., 37T Fourth Ave., Hawthorne,NJ 07506; Tel: 973-427-3337, Fax: 800-643-2580, www.HawthorneRubber.com

Hawthorne Rubber

A WORLD OF FIBER OPTICSOLUTIONS

• T1/E1 & T3/E3 Modems, WAN• RS-232/422/485 Modems and Multiplexers• Profibus-DP, Modbus• Ethernet LANs• Video/Audio/Hubs/Repeaters• USB Modem and Hub• Highly shielded Ethernet, USB (Tempest Case)• ISO-9001http://www.sitech-bitdriver.com/

S.I. Tech

Defense Tech Briefs, February 2013  www.defensetechbriefs.com 55

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56  www.defensetechbriefs.com Defense Tech Briefs, February 2013

Published by ............Tech Briefs Media Group, an SA E International Company 

Publisher....................................... ............................Joseph T. Pramberger

Editorial Director .................................... ...................................Linda L. Bell

Editor, DTB, PTB and Embedded Technology ..........................Bruce  A . Bennett

Technical/Managing Editor ....................................... ..................Ted Selinsky 

Technical Writers.......................................................................Shirl PhelpsNick Lukianoff

Managing Editior, Tech Briefs.TV ...................................... .........Kendra Smith

Associate Editor ...................................... ...................................Billy  Hurle y 

Produc tion Manager ........................................................... Adam Santiago

Assistant Production Manager .................................... .........Danielle Gaglione

Art Director ...................................... ......................................Lois Erlacher

Designer...............................................................Bernadette Torres

Marketing Director..............................................................Debora Rothwell

Marketing Assistant .................................... ..........................Felicia Kennedy 

Circulation Manager..............................................................Marie Claussell

Circulation/Audience Development Coordinator .....................Brandie Denlinger

TECH BRIEFS MEDIA  GROUP,  AN SA E INTERNATIONAL COMPAN Y 261 Fifth  Av enue, Suite 1901, New York, N Y 10016(212) 490-3999 FA  X (212) 986-7864

Chief Executive Officer ...................................... ...........Domenic  A . Mucchetti

Executive Vice-President ..................................... ...................Luke Schnirring

Technology Director...............................................................Oliv er Rockwell

Systems Administrator ...................................... ..................... Albert Sunseri

Web Developer................. ........................................ ............Karina  Adames

Online Content Manager/Web Developer ...........................................Peter Bona vita

Digital Media Producer ..................................................................................Phil  Abalos

Digital Media Assistant .............................................................................Ranard Miller

Credit/Collection......................................................................Felecia Lahe y 

Accounting/Human Resources Manager............................ .............Sylvia Ruiz

Office Manager.................................................................... Alfredo  V asquez

Receptionist .................................. ..........................Elizabeth Brache-Torres

DEFENSE TECH BRIEFS A D V ERTISING A CCOUNT EXECUTIV ES

CT, MA, NH, ME, VT, RI, Eastern Canada.......................................Ed Marecki

......................................................................................... Tatiana Marecki

at (401) 351-0274

NJ, PA, DE..............................................................................John Murra y 

at (973) 545-2132

NY ...................................... ....................................... ........Stan Greenfield

at (203) 938-2418

 VA, MD, DC, NC, SC, GA, FL, AL, TN, MS, LA, AR, OK, TX, WV ....Ra y  Tompkins

at (281) 313-1004

Western NY, OH, MI, IN .................................... .....................Ry an Beckmanat (973) 409-4687

MN, ND, SD, WI, IL, KY, MO, KS, IA, NE, Central Canada.................Bob Case y 

at (847) 223-5225

Northwest, N. Calif., Western Canada........................................Craig Pitcher

at (408) 778-0300

Bill Hague

at (310) 457-6783

CO, UT, MT, WY, ID, NM .................................. ...........................Tim Powers

at (973) 409-4762

S. Calif., AZ, NV................. ........................................ ...................Tom Boris

at (949) 715-7779

Integrated Media Consultants..................................................Patrick Harv e y 

at (973) 409-4686

 Angelo Danza

at (973) 874-0271

Michael Barboza

at (973) 545-2565

Jason  W einstein

at (973) 545-2566

Tom  Wright

at (973) 545-2464

Reprints ....................................... ....................................... ......Jill Kaletha

at (866) 879-9144, x168

www.defensetechbriefs.com

ADVERTISERS INDEX

 ACCES I/O Products..................................801 ......................18

 Ace Controls Inc. ........................................795 ........................9

 Aerocon Orlando........................................796 ......................53

 AeroDef 2013 ..............................................819 ......................51

 Aeroflex ......................................................813 ......................44

 Aurora Bearing Company ..................806, 817 ................28, 49

 Avnet Electronics ........................................791 ........................1

COMSOL Inc. ....................................832, 825........55, COV IV 

Create The Future Design Contest............................................7

Crescent Industries Inc...............................800 ......................16

CRYOCO LLC ............................................814 ......................48

CST of America Inc. ..................................824..............COV III

Dexmet Corporation ..................................804 ......................24

EMCO High Voltage Corporation ............816 ......................49

FEKO - EM Software & Systems (USA) ....810 ......................41

Fischer Connectors ....................................815 ......................47

Gage Bilt Inc................................................808 ......................33

Hawthorne Rubber Mfg. Corp...................833 ......................55Herber Aircraft Service Inc. ......................818 ......................50

HoodTech Vision ........................................794 ........................5

M.S. Kennedy Corporation ........................792 ........................2

Master Bond Inc. ........................................834 ......................55

Maxon Precision Motors Inc. ....................798 ......................14

Mini-Systems Inc. ........................................809 ......................39

Morehouse Instrument Company..............799 ......................15

New England Wire Technologies ..............797 ......................13

New Hampshire Ball Bearing ....................805 ......................27

OFS | Specialty Photonics Division ............821 ......................52

Omicron USA..............................................802 ......................19

Power Technology ......................................790 ..............COV II

PPG Industries ............................................807 ......................29

Proto Labs Inc.............................................793 ........................3

S.I. Tech. ......................................................835 ......................55

SAE International ......................................822 ......................11

Servometer®/PMG LLC ............................820 ......................52

Stratasys........................................................803 ................22 - 23

Tech Briefs TV ..........................................................................45 W.L. Gore ............................................811, 812 ................42, 43

For free produc t litera ture, enter adv ertisers’ reader service numbers a t www. techbriefs.com/rs, or  visit  the Web site benea th  their ad in  this issue.

Reader ServiceCompany Number Page

Reader ServiceCompany Number Page

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RCS & Surface Current Simulation

of a Helicopter

CST of America®, Inc. | To request literature (508) 665 4400 | www.cst.com

• Components don’t exist in electro-

magnetic isolation. They influence

their neighbors’ performance. They

are affected by the enclosure or

structure around them. They are

susceptible to outside influences.

With System Assembly and Modeling,CST STUDIO SUITE helps optimize

component and system performance.

Working in aerospace and defense?

You can read about how CST techno-

logy was used to simulate the RCS &

surface currents of this helicopter at

www.cst.com/heli. 

If you’re more interested in filters, cou-

plers, planar and multilayer structures,

we’ve a wide variety of worked applica-

tion examples live on our website at

www.cst.com/apps.

Get the big picture of what’s reallygoing on. Ensure your product and

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Choose CST STUDIO SUITE –

Complete Technology for 3D EM.

Find the simple way through complex

EM systems with CST STUDIO SUITE

Make the Connection

Free Info at http://info.hotims.com/45600-824

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®

Multiphysics tools let you build simulations that accurately replicate theimportant characteristics o your designs. The key is the ability to include all

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CAD Import Module

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CONJUGATE HEAT TRANSFER: Multiphysics simulation of an aluminum heat sink forcooling of components in electronic circuits. Heat transfer by conduction, convection andradiation are taken into account where all material properties are temperature-dependent.

COMSOL Version 4.3a

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 account where all material properties are temperature-dependent.