Grant SuccessCongratulations to the following for their success in

their grant applications:

Associate Prof Chua Han Bing (CELTEX RM220K)

Process Modeling and Optimization of Composting of

Empty Fruit Bunches (EFB) from Oil-palm for

Development of High Quality Organic Compost

Dr Ujjal Ghosh (FRGS RM80.5K)

Fundamental Model Development for Water Gas Shift

Membrane Reactor for Greenhouse Gas Capture from

Pre-combustion Processes.

Dr Perumal Kumar (ERGS RM53K)

Studies on the effect of viscoelasticity on the heat

transfer performance of Al2O3 – water nanofluid in

circular and noncircular ducts

Dr Leblouba Moussa (ERGS RM50K)

Innovative Vibration Isolation Systems for Equipments

and Structures

July 2012

School of Engineering & Science

In this issue

Intelligent biomechanical vision system – MUSCLE motion P.3

Origami and its Applications in Automotive Field P.5

Empowered Consumer’s Demand Side Response in Electricity Market P.7

Nonlinear Model for Lead-Rubber Bearing Isolator P.9

The Unusual Stalagmites of the Niah Caves P.10

Effect of Aeration Rate and Stirrer Speed on Micro-Aerobic Batch

Fermentation Process P.12

Growth of TiO2-ZrO2 Binary Oxide Electrode with Henna Leaves for Dye-

Sensitized Solar Cell Application P.14

The July issue of R&D focus features articles from the interdisciplinary research groups within the School of

Engineering & Science (SOES). The breadth of the articles covers the four multidisciplinary research groups,

namely, the Energy and Environment Group, the Intelligent Systems and Design Group (ISD), the Peat and

Structures Group and the Materials, Mechanics and Manufacturing Group. We also highlight some of the research

areas in the ISD research group. Enjoy reading!

1

Editors: R&D Committee

Internal Funding Opportunities

•Curtin Sarawak Research Fund (CSRF)

•Curtin Sarawak Research Clusters Fund (CSRCF)

•Curtin Sarawak Collaborative Research Scheme

(CSCR)

•Curtin Sarawak Academic Grant

"The

grea

t univ

ersity

... sh

ould

look

ever

forwa

rd; fo

r it t

he pa

st sh

ould

be b

ut a

prepa

ratio

n for

the

grea

ter d

ays t

o be".

Joh

n C

urtin

R&Df cus

ISD Research Group

The Intelligent Systems & Design (ISD) is one of

the four research groups in SOES. It is a

multidisciplinary research group, which focuses

on:

• Multi-scale Control

• Control System Modelling

• Complex System Design

• Signal Processing

• Integrated Energy System

See page 2 for details

ISDadopts

Modelling,

Optimization &

Control Theories

in the

creation of optimal

solutions

to complex problems

of practical

importance to

the society

2

The Intelligent Systems & Design Group

ISDadopts

Modelling,

Optimization &

Control Theories

in the

creation of optimal

solutions

to complex problems

of practical

importance to

the society

Signal Processing

0

2000

4000

-60-50

-40-30

-20

-35

-30

-25

-20

-15

Frequency (Hz)

Su

pp

ressio

n (

dB

)

Distortion (dB)

=1

=0.5

=0

Top Left: Subband signal processing with filter banks. Top Right: Optimization of Microphone arrays – efficient frontier as functions of J1 (noise power) and J2

(distortion). Bottom: Proposed structure of spatio-temporal processing for distance speech recognition

Complex System Design

Top Left: Vinyl acetate plant design for resource conservation. Top Right: Integrated CO2 capture in coal-fired power plant. Bottom: Integrated proton exchange membrane fuel cell –fuel processor (PEMFC-FPS) system

Complex System Modelling

Top Left: Empirical modelling methodology for complex biosystem under limited experimental data. Bottom Left: Transformed fermentation kinetic parameter of S. cerevisiae vs. aeration (AR) and stirring speed (SS). Top Right: Metabolic fermentation pathway in S. cerevisiae yeast [1]. Bottom Right: Framework of multiscale modeling for bio-technological systems

Integrated Energy System

Left: Fully-integrated agro-biofuel-biomaterial-biopower cycle for sustainable technologies [2]. Bottom: Proposed topological integration of multi-energy sources (wind, solar, hydro and coal power plants)

References[1] M. Rizzi, M. Baltes, U. Theobald & M. Reuss. Biotechnol. & Bioeng. 55(4): 1997[2] A.J. Ragauskas et als. Science, 311: 2006

Top Left: Multiscale feedback control (MSC) scheme vs. LQG and PID. Top Right: Block diagram of generalized MSC scheme. Bottom Left: Multiscale control system employing multi-scale structure (MSC). Bottom Right: MSC vs. single-scale control structure (SSC)

Multi-Scale Control

Intelligent biomechanical vision system –MUSCLE motion

Alpha Agape Gopalai & Lim King Hann

4

Visual-based tracking system in rehabilitation provides a suitable platform for continuous monitoring of

patients in identifying and correcting gait related problems. Visual systems in human motion analysis can

be classified into two sub-categories: (1) visual marker tracking system, and (2) markerless tracking

system. Visual marker tracking system requires skilled knowledge for mounting visual markers on

subjects’ body and encumbers human motion. Therefore, markerless visual tracking system presents

itself as a great potential alternative in human motion analysis. However, this alternative faces several

critical challenges: (1) Segmentation of fast human motion without introducing significant amount of

noise, (2) Occlusion of region of interest due to rotation or overlapping regions, (3) Synchronization and

fusing of scenes from multiple cameras (multiview), in order to reduce the occurrences of occlusion, and

(4) Ability to correct/communicate errors or abnormalities in real-time, when observed. The study

proposes a Markerless Multiview System for Corrective Lower Extremity Motion (MUSCLE Motion), in

order to overcome the four identified challenges of markerless tracking systems. The MUSCLE Motion

consists of a markerless motion analysis system that provides reliable real-time motion capture system

and joint kinematic parameters. These data is processed using computerized artificial intelligence to aid

in real-time identification of gait asymmetries and abnormalities of ambulation patterns. The proposed

system is expected to perform at par or better than current sensing technologies (visual markers or

sensing methods). MUSCLE Motion will also include an intelligent bio-feedback module, enabling the

system to communicate detection of abnormalities and asymmetries to the subject in an effective

manner. Successful implementation of MUSCLE Motion will see changes in current rehabilitation

techniques. The incorporation of artificial intelligence and accurate automation of processes within the

system will cause rehabilitation routines to no longer be confined to a facility or limited by the availability

of specific professionals.

Figure 1: An overview of the MUSCLE motion detailing the integration of the various components that

are required

3

5

Biomechanics is a division of science which

provides sound and logical basis to evaluate

motion and stance of human beings. This field of

study allows for engineers and scientists to

understand the wide variety of human physical

movements, which are achieved by the human

neuromusculoskeletal system and can range from

walking to the skilful performance of a professional

athlete. In the past two decades, the knowledge of

biomechanics has been widely applied in clinical

rehabilitation by utilizing mechanisms or

techniques to correct abnormal motion behaviour

to achieve better or near ideal posture. In addition

to that, with the aid of rehabilitative mechanism,

improved posture may be gained enabling

individuals experiencing injuries or disabilities to

regain highest possible level of independence .

In rehabilitation routines, the movement of

patients have to be continuously monitored and

rectified to maintain correct forms of motion. The

real-time monitoring and rectification of the

undesired motion behaviours during initial

rehabilitation stages are crucial for the re-learning

of motor skills. This is because brain plasticity and

adaptation depends heavily on provided stimulation

(natural or external). With the development in

biomechanics, various methods and tools for

collecting dynamic and kinematic parameters of

human posture have emerged. In the past

decades, human motion tracking methods using

various types of methods have been intensively

studied to help understand the various

biomechanical aspects of human movement.

Generally, human motion tracking technologies can

be categorized in to two major categories: (1) non-

visual tracking system, and (2) visual-based

tracking system.

Non-visual tracking systems function by

employing sensory tools to collect dynamic and

kinematic parameters of human posture. This

method is popular due to its mobility, compactness,

and efficient processing signal characteristics.

Inertial Measurement Unit (IMU) sensors are

among the many kind of available sensing

technologies which are widely used for human

motion monitoring. IMUs consist mainly of

accelerometers and gyroscopes. These sensors

are attached to human body/joints to record

movement information such as velocity, orientation,

and gravitational forces. Signals are analyzed by

monitoring the signal characteristics and occurring

clusters. However, a non-visual approach would

require foreign objects (sensors) to be attached to

the human body. This could affect and influence

the natural response of patients’ gait patterns.

Furthermore, a system of this nature would also

require the presence of trained personnel to assist in

the attachment of sensing nodes (or a knowledge to

do such) on the human body – limiting its application

in the wider society.

Visual-based tracking system using cameras,

however, are widely used to improve accuracy in

position estimation. This system can be further

classified into two sub-categories: (1) visual marker

tracking system and (2) markerless tracking system.

Visual marker tracking systems or marker based

tracking systems utilize simple image processing

techniques to identify human motion with the aid of

identifiers/markers on the human body, to identify

location of joints. Therefore, the major drawback

when using the maker based approach is that

rotated joints or overlapping body parts with markers

cannot be detected, which leads to difficulties in

determining the joint parameters. Marker based

systems also require for a trained personnel (or a

knowledge to do such) to be involved when placing

the markers on the joints/limbs.

In view of the limitations of the current available

technologies, markerless visual tracking system is

currently an intensive exploratory research area.

Researchers are looking at methods to locate human

joints automatically and to analyze joint parameters

using computerized intelligence without the aid of

identifiers (markers). A successful implementation of

this objective will see the acquisition of patients’

natural motion data in environments comfortable and

familiar to them (in the comforts of their home), thus

allowing for improved identification of pathological

problems. With the decreasing cost of optical

sensors and increasing performance of

microcomputers, it is now possible for the processing

of high volumes of captured visual frames in real-

time. This is a vital element to the viability of a real-

time markerless video tracking approach.

This work proposes the use of an automated

markerless vision system for rehabilitation, using an

intelligent bio-feedback system as the means of

correcting and improving monitored postures.

Outputs (kinematic parameters) from the vision

system will be analysed further to determine the

quality of postures or presence of asymmetries. This

decision on posture quality will be made using a

designed artificial intelligent model and will trigger

the necessary bio-feedback modalities.

Figure 2:

Summary of

the proposed

system and

its

relationship

with the

various

proposed

sub-systems4

Origami and its Applications in Automotive

FieldSujan Debnath

5

1. INTRODUCTION

Origami is the art of folding originated from

Japan and has been commonly practiced

worldwide. Traditionally square papers are

folded into 2 or 3 dimensional figures as

resemblances of existing matters like birds,

mammals, trees, furniture etc. As the

application is being introduced to the

scientists and engineers, Origami has

become a useful tool in design and fabrication

of appliances. Till date the folding is no longer

being restricted to square papers. Many

industry applications use origami technique in

designing new products. The Eyeglass space

telescope as shown in Fig. 1 designed by

Robert Lang is a great example in merging

origami and engineering.

FIG.1 Eyeglass designed by Robert Lang

(adopted from origami-resource-center.com)

2. ORIGAMI SCIENCE: The Fundamentals

Origami originated as a trial-and-error art

design for making paper(s) to appear like

real object by folding them. Later on several

mathematical approaches were developed

to understand the phenomena on the paper

generated by the folding and also to

estimate the outlook of the origami (folded

paper)

Mathematical approaches for Origami, to

name a few, are Geometry, Topology

(explained by Thomas Hull [1]), Robert

Lang’s Tree Theorem [2] and Maekawa’s

String-to-beads method [3]. The Tree

Theorem approaches are surrounding three

main fundamentals: Huzita-Hatori axioms,

Kawasaki and Haga’s theorems. The

components of of Tree Theorem are

molecules and stick figure also referred as

tree graph (Fig. 2)

• Given two points P1 and P2, there is a

unique fold that passes through both of

them.

• Given two points P1 and P2, there is a

unique fold that places P1 onto P2.

• Given two lines l1 and l2, there is a fold

that places l1 onto l2.

• Given a point P1 and a line l1, there is a

fold that places P1 onto l2.

• Given two points P1 and P2 and a line l1,

there is a fold that places P1 onto l1 and

passes through P2

• Given two points P1 and P2, and two

lines l1 and l2, there is a fold that places

P1 onto l1 and P2 onto l2.

• Given one point P1 and two lines l1 and

l2, there is a fold that places P1 onto l1and is perpendicular to l2.

FIG. 3 Bases of folding methods (1) Cupboard, (2) Windmill,

(3) Water bomb, (4) Preliminary Fold (adopted from [2])

The notations of Origami have been

standardized by scientists, to name a few,

including Lang, Huffman, Clowes, Waltz,

Takeo Kanade, and Akira Yoshizawa [2] & [5].

In summary, the notations being widely used in

the Origami practice are made of lines, arrows,

and terms as illustrated in Fig. 4 and Fig. 5.

(1)

(4)(3)

(2)

The basic folding methods in the industry

are the Cupboard Base, Windmill Base,

Water bomb Base, and Preliminary Fold [5]

as illustrated in Fig. 3.

The Huzita-Hatori axioms consist of 7

axioms were improved by Humiaki Huzita

and finalized by Koshiro Hatori, Justin and

Robert Lang in 2001. The axioms [4] are:

FIG.2 Top projection of an origami provides a tree graph

(adopted from [2])

5

The focus on type of windshield in this article is

for standard motorcycle. It provides full

protection from flying debris and wind when the

motorcycle is moving forward.

There are mainly two types of wind shield for

motorcycle: one allows the rider to look through

the windshield while the other not. The types of

windshield are illustrated in Fig. 6. In this project,

the latter type is chosen due to its suitability for

warm climate [6] as it is in Malaysia. Also it is

because of the consideration of providing a

minimal disturbed view to the rider on the road.

FIG. 6 Types of motorcycle windshield (adopted from [6])

Weight (Material): In practice the two most

common materials for motorcycle

windshield are polycarbonate (Lexan) and

acrylic (Plexiglas) [6]. They are chosen due

to their great transparency degree, strength

of materials, and durability in molding the

plastic. With the application of Rigid

origami, the panels (pieces of

polycarbonate) selection would based on

the available thicknesses from the

manufacturer.

Optical Consideration: The windshield

should not be an obstacle to the visibility of

the rider on the road (e.g. the road mark

should not appear to be bent to the rider).

Transparent material is to be used with

suitable coating for sunlight filtration.

Folding Process: At this stage the design of

the windshield involves manual unfolding

and folding process. Miura fold is to be

considered before further design

modification is done using Tree Maker and

Rigid Origami.

Attach Method: It is proposed for the

unfolded windshield to be attached to the

Rack using firm clip-on method.

4. CONCLUSION AND FUTURE WORKS

This article has presented the findings on

Origami science which mainly focus on the

Robert Lang’s Tree Theorem, the

fundamentals, Rigid origami and one of its

applications. Beyond this paper are works on

detailed designing a foldable (and usable)

motorcycle windshield with all the studied

Origami fundamentals and aiding software.

REFERENCES

[1] Andersen, Eric M. Eric's Origami Page -

Origami and Mathematics. 2004.

[2] Lang, Robert J. "TreeMaker User Manual.

"Langorigami. 2004. www.langorigami.com

[3] Lang, Robert J. Origami Design Secrets -

Mathematical Methods for an Ancient Art.

Massachusetts: A K Peters Ltd, 2003.

[4] Barile, Margherita, & Margherita Barile.

"Kawasaki's Theorem." From MathWorld--A

Wolfram Web Resource, created by Eric W.

Weisstein.http://mathworld.wolfram.com/Kawasaki

Theorem.html

[5] Kanade, Takeo. "A Theory of Origami World."

Artificial Intelligence, 1980: 280-311

[6] Lawrence, Mark. Windshields. 2007.

http://www.calsci.com/motorcycleinfo/Fairing.html

FIG. 4 Terms used in a typical Origami folding

(adopted from [3])

FIG. 5 Types of lines used in Origami (adopted from [2])

Types of Wind Shield

Wind Shield Design Parameters

Height: For a windshield to be shorter than the

rider after installation, a methodology

introduced by Mark Lawrence [6] is used to

determine the dimension of the windshield for

this project. The desired dimensions of the

windshield are found to be 40cm x 60cm (width

x height). These dimensions have included the

mounting requirement.

3. WIND SHIELD DESIGN USING ORIGAMI: An

Ongoing Project

6

Empowered Consumer’s Demand Side

Response in Electricity Market Fouad Kamel

It is generally agreed that consumers, at the tail-

end of electricity market, inherently possess the

ability to moderate the market and avoid most of

the currently experienced problems occurring

mainly due to demand congestions. Those

congestions are mainly due to lack of

coordination among consumers as well as

between consumer and suppliers [1]. With

adequate information about basic economic and

technical market operating conditions, consumers

could be able to contribute alleviating demand

congestions and achieve enhanced economic

performance.

Under the smart grid, consumers will be an

integral part of the power system, where they are

encouraged to participate in system operation

and management. From the perspectives of

market operators controllable demand is another

resource; it will help balance supply and demand

to ensure system reliability and moderated

energy price.

The proposed scheme is acting upon publicly

available 30 minutes periodical information on

demand and price conditions released and

updated by the Australian Energy Market

Operator (AMEO) on the internet [2]. Figure 1

depicts an example of actual energy demand and

price conditions in Queensland. The price pattern

is closely following that of the demand. Electricity

price is typically at its lowest level during times of

low demand (off-peak) e.g. at night. Traditionally,

prices soar twice daily following morning and

evening peak demands.

1

Fig. 1: Wholesale electricity price in Queensland on 2nd - 4th May 2010 [2].

Introduction:

The proposed scheme comprises a technical set-

up of a programmable internet relay, a router,

solid state switches in addition to the suitable

software to control electricity demand at

consumer’s premises. The software on

appropriate multimedia (CD Rom) offers

consumers optimizing control of energy

consumption [3]. The relay is programmed to

receive and act upon information received about

electricity demand/price conditions every 30

minutes from the Australian Energy Market

Operator (AEMO) over the internet. The scheme

is presenting a low-cost DSR technique, which

assists electricity consumers to be shifting loads

around the clock averting peak-demand periods.

This shall help consumers to be engaged

mitigating peak demands on the electricity

network.

The scheme is primarily applicable for

commercial and industrial consumers on

fluctuating energy prices. For domestic

consumers on flat-rate tariffs, users are gaining

financial benefits from reducing energy

consumptions at certain times a day; mainly

averting peak-load periods. Domestic consumers

on different tariffs, where energy price differs with

day time and network conditions (e.g. night

tariffs) will be gaining financial benefits from

shifting loads from day- to night-times, when

electricity cost is lower. The scheme is expected

to be helping alleviating congestions on the

electrical network in Australian States covered by

the Australian Energy Market Operator (AEMO)

and other markets in similar operating condition.

Methodology:

7

8

[1] Kirschen D.S., Strbac G., Cumperayot P.,

and De Paiva Mendes D. (2000) "Factoring

the elasticity of demand in electricity prices"

in Power Systems IEEE 15 (2) pp. 612-617

http://ieeexplore.ieee.org/stamp/stamp.jsp?tp

=&arnumber=867149

[2] Australia Energy Market Operator Current

Trading Interval Price and Demand Graph

Queensland. Retrieved from

http://www.aemo.com.au/data/GRAPH_30QL

D1.html

[3] Fouad Kamel and Marwan M. (2011)

"Smart Grid Techniques for Optimized

Energy Use" in Proc. Innovation in Power,

Control, and Optimization: Emerging Energy

Technologies, Pandian Vasant, Nadar

Barsoum and Webb J., Editors IGI Global:

Hershey USA.

Numerical example:

Fig. 2: Control Regime

Fig. 3: Occurrence of electrical energy demand in

Queensland during 2010 with average 5957 MW

The proposed DSR scheme aimed to develop

an integrated energy scheme that enables

electricity consumers to gain autonomous

control on own energy consumption securing

financial and energy savings to consumers.

The scheme is helping engaging consumers to

be participating in solving peak demand

congestions on the electrical network in

Australian States covered by the Australian

Energy Management Operator (AEMO) and

on other electricity markets in similar operating

conditions.

Conclusion:

To enable electricity consumers to control

electrical demand, a Demand Site Control Unit

(DSCU) and controllable switches are required.

Figure 2 depicts a DSCU controller [3]. Up to

date demand and price profiles are available

online on the Public Load Profile Web Server

(PLPW), in Australia the National Electricity

Market Operator (AMEO). The controller is

connected to the Internet and has access to the

PLPW. Many households and businesses have

broadband Internet connections. Wireless

broadband is also easily deployable at a low

cost when existing installations can not be used.

The DSCU controller is implemented in a simple

embedded router device commonly used in

home and office networks. This device connects

to the Internet as well as local appliance

switches via the home network. It controls the

appliance switches which in turn activate

appliances. At regular intervals, i.e. every 10

minutes, the control system downloads the

load/price information from the AEMO server

and evaluates the appliance profile. If

preconditions for appliances are met, power to

these units is turned on; if the cut off threshold is

reached devices are turned off.. Figure 2

illustrates the control regime, where e.g. three

appliances are controlled by three solid-state

switches receiving on/off signals from the relay.

Figure 3 depicts the case where the proposed

scheme is able to allow consumers to defer loads

from times of peak-demand to times of low-

demands. Such a procedure shall help flattening

the total energy demand to meet a constant

average of 5957 MW for Queensland, achieving a

plant utilization factor close to unity corresponding

to optimal economics. In such a procedure the

technique enables deferring 3.175 TWh/year from

peak to off-peak times.

The scheme:

References:

Nonlinear Model for Lead-Rubber Bearing

Isolators

However, this model addresses only small

rotations and the determination of its nominal

parameters are based on judgment.

Nonlinear Macro-Element Model

The proposed macro-element model of the LRB is

shown in Figure 2. The system of equations that

governs the motion of the proposed model is as

follows:

Leblouba Moussa and Muhammad E. Rahman

The seismic isolation is a relatively new

technique and innovative approach in seismic

resistant design of structures. The seismic

isolators are simply incorporated to provide

discontinuity between two bodies in contact so

that the motion of either body in the direction of

the discontinuity cannot be fully transmitted.

Figure 1 shows the lead-rubber bearing isolator,

this device has been used extensively in many

constructions.

Several factors are often considered in the

selection and design of seismic isolation devices.

The selection of the appropriate seismic isolator

is based on some requirements ranging from the

lateral and vertical stiffness, cost benefits to the

durability. The design of isolation systems takes

into consideration the stability of individual

isolators and that of the structure as one block.

Studies performed on single elastomeric

bearings1,2,3.demonstrated that bearing devices

show a general reduction of stiffness with

increasing axial loads. Rubber bearings have

also been shown to soften in the vertical direction

at large deformations. The characteristic strength

of Lead-Rubber Bearing (LRB), defined as the

maximum force at zero bearing horizontal

displacement has been observed to increase with

increasing vertical axial load on the bearing, but

decreases from cycle to cycle.

Based on the fact that most isolation bearings are

inherently nonlinear, especially Lead-Rubber

Bearing due to the yielding of lead core, a

nonlinear extension of the linear two-spring

model1 was proposed by Ryan et al.3, this model

includes a linear vertical spring to account for the

axial load effects, and as an option a model for

lead strength degradation was incorporated to the

Coupled Nonlinear Variable Strength Model4.

References1. Koh, C. G., and Kelly, J. M., UCB/EERC-86/12 (1987).

2. Aiken, I. D., Kelly, J. M., and Tajirian, F. F., UCB/EERC-89/12 (1989).

3. Farzad Naeim, Hussain Bhatia and Roy M. Lobo, in Seismic Design Handbook,

Edited by Farzad Naeim, Kluwer Academic Publishers (2000), Edition 2, Chapter

14, pp.723-756.

4. Ryan K. L, Kelly, J. M., and A. K. Chopra, J. Eng. Mech-ASCE. 131, 1270

(2005).

5. Skinner, R. I., Robinson, W. H., and McVerry, G. H., An Introduction to Seismic

Isolation, John Wiley, New York (1993).

9

Fig.1: Lead Rubber Bearing (Taiwan Pillar)

Fig.2: Proposed Macro-element Model

Comparison With Experimental Tests

The proposed macro-element model is used to

simulate the behavior of the New Zealand LRB5.

Figure below shows the capability of the proposed

model in predicting the behavior of LRB.

The unusual stalagmites of the Niah caves

Their mode of formation is complex and involves

wind deflection of ceiling drips, light triggering

colonization and photosynthetic activity by

cyanobacteria and accretion of aeolian material on

the bacterial mucilage.

Research findings

Our research involved description of the

stalagmite morphology, mapping their location

and other cave features and measuring light

intensity in the cave. Significant differences

between stalagmites in the darker cave zone and

those of the brighter entrance were found. Also

noted were differences between the stalagmites in

the Painted Cave and craybacks reported

elsewhere in the world. Several new features

have been documented at this site.

The Painted Cave specimens have axial

orientations that differ in the different zones of the

cave. The results suggest that this aspect of their

morphology is predominantly controlled by cave

wind (Figs. 2 and 3).

Dominique Dodge-Wan

Figure 1: Some of the unusual elongated stalagmites, with arrows showing

crenulations. The lateral crenulations in 1a are angled towards the light,

suggesting cyanobacteria may have influenced the stalagmite growth.

The Painted Cave is a subhorizontal relict tunnel

passage which runs through a small karst tower,

approximately 30m above the surrounding

alluvial plain and adjacent to other large karst

towers in Niah National Park (Sarawak,

Malaysia). Whilst mapping the cave over twenty

very unusual stalagmites were observed (Fig. 1).

They are clustered in two zones of the cave (Fig.

2). One is close to the cave entrance and

receives plenty of natural light. The other is

further away from the entrance and mush darker.

Both zones are characterised by cave wind due

to air circulating through the cave tunnel.

The stalagmites are similar to craybacks, a rare

type of stalagmite, only found in a few places in

the world. This site may be unique in having one

of only two currently known large groups of

crayback-like stalagmites.

Crayback stalagmites

Craybacks are stalagmites that are elongated

(not round like classic stalagmites). Their

morphology includes a taller rounded head and a

sloping tail section marked by transversal

crenulations (as in Fig. 1b).

10

Several features of the crayback-like

stalagmites in the North entrance zone suggest

that cyanobacteria are present and played a

role in the formation of the mineral deposit.

Of particular interest are lateral crenulations

that are oriented facing the light in certain

specimens (Fig. 1a). Where active deposition

of calcium carbonate is occurring on these

stalagmites there is a characteristic purple

colouration.

Cyanobacteria are common on many surfaces

in these open caves: cave walls, fallen blocks,

sediment covered floors, stalagmites and

stalactites. The cyanobacteria form biofilms on

these surfaces, and give them a typical

greenish hue. A limited amount of sampling of

these biofilms has been initiated (under Permit

from Sarawak Forest Department). Both

filamentous and coccoid cyanobacteria have

been observed. Some of the filamentous

cyanobacteria have mineralised sheaths (Fig.

4).

Conclusions

The observations to date in the Painted Cave

indicate that there exists a wider spectrum of

crayback morphologies than previously

documented. Several new morphological

features have been described for the first time:

flat-topped zones, bulbous heads and micro-

rims. It is hypothesised that the mode of

formation of crayback-like stalagmites ranges

from being influenced only by wind, and

entirely abiotic to being strongly influenced by

cyanobacterial growth. As tropical karst cliffs

retreat due to erosion, previously dark cave

areas with abiotic stalagmites are exposed to

light, with the possibility of cyanobacterial

inoculation and subsequent influence on cave

mineral deposits.

Future research will include observations at

additional cave locations at Niah and in

particular on similarities between crayback-like

stalagmites and tufaceous stalactites.

Figure 2: Rose diagram of stalagmite

axial orientation. Note similarities with

cave wall orientations in Fig.3

Figure 4: Microscope view of calcified

branching cyanobacterial filament from a

Niah stalagmite (filament is 20 microns

wide including the outer calcium

carbonate sheath.)

11

Figure 3: Map of the Painted Cave showing

zones A and B where the stalagmites are

located

Effect of Aeration Rate and Stirrer Speed on

Micro-Aerobic Batch Fermentation Process Emily Liew Wan Teng

Growing environmental concerns due to the

usage and depletion of non-renewable fuel

sources has indeed created vast interest in large

scale production of alternative fuels such as

ethanol. The production of this energy source

from renewable agricultural residues or hardwood

species has been predicted to substitute 20% of

fossil-based fuels by ethanol within the next 15

years, but significant scientific knowledge and

technological investments will be required in

order to achieve this objective.

Traditionally, Saccharomyces cerevisiae (Baker’s

yeast) has been used as the main type of yeasts

in the production of alcohol and it has been

widely used in industry. Saccharomyces

cerevisiae has been utilized by the main

industrial ethanol producers since it is considered

as a model organism, which is generally

regarded as safe microorganism that could

generate up to 20% ethanol from carbon sources.

Previous experimental works suggested that

microbes respond differently to an increment in

glucose supply, e.g. a variable lag phase after

inoculation with an uncontrolled pre-culture. Due

to the glucose increment content, the increased

flux of sugar entering the yeast cells results in an

increased production of NADH, which could not

be fully oxidized by the respiratory chain. In order

to remove the excess NADH, production of

ethanol by fermentation is required, i.e. the basis

of aerobic alcoholic fermentation.

On the other hand, there are certain limitations

which pose serious industrial challenge in the

utilization of Saccharomyces cerevisiae. The

most recognized challenge to date is the

inhibition of fermentation process by

accumulation of ethanol. This is due to the

reduction of metabolic activity by decreasing

glucose and ammonium uptake and the induction

of stress responses. Besides that, the production

of by-product, i.e. glycerol, and the reduction of

cell viability in conventional anaerobic

fermentation will lead to low ethanol productivity.

In large-scale bioreactors, it is impossible to

maintain full levels of oxygenation. With this

challenge in mind, part of the motivation of the

study described the performances of

Saccharomyces cerevisiae under different sets of

micro-aerobic environmental conditions, i.e. with

respect to different sets of aeration rates and

stirrer speeds in lab-scale batch bioreactor.

Micro-aerobic fermentation is of interest since

this type of process could provide improvement

to the ethanol tolerance of yeast and thus, leading

to increased yeast cell permeability and overall

fermentation rates. However, to date the study on

the combined aeration and mixing factors in

bioreactor have frequently been overlooked.

Thus, the key aim of this study is to investigate

the combined impact of both aeration and mixing

in micro-aerobic fermentation process.

Introduction

Materials and MethodsBIOSTAT A plus 2L, MO-Assembly is used as the

bioreactor for this study (Fig. 1). Saccharomyces

cerevisiae is utilized as the inoculum culture with

glucose as substrate. 1.5L of fermentation

medium is prepared by adding 75g glucose, 7.5g

yeast, 3.75g NH4Cl, 4.37g Na2HPO4, 4.5g

KH2PO4, 0.38g MgSO4, 0.12g CaCl2, 6.45g citric

acid and 4.5g sodium citrate. The medium culture

is sterilized at 121 C for 20 min and then cooled

down to room temperature. 40mL of yeast

inoculum is added to the fermentation medium.

Temperature and pH conditions are maintained

and controlled at 30 C and pH 5 respectively. The

batch process ended after approximately 72 hrs

and samples are taken every 2-3 hrs. These

samples are analyzed for glucose, ethanol,

glycerol and biomass concentrations by using R-

Biopharm test kits and UV-VIS

spectrophotometer.

Results

Fig. 2: Actual glucose concentration (g/L

solution) vs. batch age (hr)

Fig. 1: BIOSTAT A plus 2L Bioreactor

12

1. Cot, M., M. Loret, J. Francois and L.

Benbadis (2007), “Physiological behaviour of

Saccharomyces cerevisiae in aerated fed-

batch fermentation for high level production of

bioethanol”, FEMS Yeast Res., Vol. 7, pp.22-

32

2. Emily, L.W.T., J. Nandong and Y. Samyudia

(2009), “Experimental investigation on the

impact of aeration rate and stirrer speed on

micro-aerobic batch fermentation”, Journal of

Applied Sciences, Vol. 9, No. 17, pp. 3126-

3130

• Ethanol production is highest under maximum

operation of both aeration rate and stirrer speed.

• Glycerol production and OUR value are highest

under maximum operation of aeration rate but

minimum operation of stirrer speed.

• Significant differences in productions of ethanol

and glycerol are due to the hydrodynamic factors

particularly under different operation of aeration

rate and stirrer speed.

• Both glucose and biomass concentrations show

comparable results although operated under

different aeration rate and stirrer speed. Glucose

concentration decreases and biomass

concentration increase along the fermentation

batch time.

Fig. 4: Actual glycerol concentration (g/L

solution) vs. batch age (hr)

Fig. 5: Actual biomass concentration (g/L

solution) vs. batch age (hr)

Fig. 3: Actual ethanol concentration (g/L

solution) vs. batch age (hr)

Fig. 6: Oxygen uptake rate (OUR) (mM/hr) vs.

batch age (hr)

Generally, similar trends can be identified

whereby there is increment in ethanol production

and its byproduct, glycerol with increase in

aeration rate and stirrer speed. As expected,

glucose concentration decrease with time. Notice

that, maximum ethanol concentration produced

when both aeration rate and stirrer speed are at

the highest condition, i.e. at 1.5LPM aeration rate

and 250rpm stirrer speed. Interestingly, from Fig.

4, the highest glycerol concentration is produced

at 1.5LPM aeration rate and 150rpm stirrer

speed. Biomass concentration on the other hand,

increases comparably under different operation of

aeration rate and stirrer speed. From Fig. 6, the

OUR value increases under the operation of

maximum aeration rate and minimum stirrer

speed conditions. A conclusion can be drawn

from the experimental results shown is that

ethanol production is affected by high rate of

aeration rate and stirrer speed. On the other

hand, the production of glycerol and OUR are

highly affected by aeration rate, i.e. stirrer speed

has lesser effect.

Conclusions

References

13

4

Growth of TiO2-ZrO2 Binary Oxide Electrode with

Henna Leaves for Dye-Sensitized Solar Cell

Application1*Z. Oo, 2S. Y. Win, 2T. T. Win, 2Y. M. Maung and 2K. K. K. Soe

1* Department of Electrical and Computer Engineering, Curtin University Sarawak

Malaysia2Department of Physics, Yangon University, Myanmar

Dye-sensitized solar cell is composite electrical

device including nanocyrstalline semiconductor

oxide film electrode, biodye sensitisers,

electrolytes, positive and negative electrode

and transparent microscopic glass. TiO2-ZrO2

fine binary oxide is firstly fabricated by

mechanochemical milling process to be

homogeneous binary oxide powder. Dye

Sensitized Solar Cells (DSSCs) is also known

as Gratzel cell based on nanocrystalline

Inorganic oxides TiO2, ZnO and SnO2, they

have attracted much attention since first

description in the beginning of 1990s by Gratzel

and O’Reagan [1]. DSSCs are new invention in

thin film solar cells, currently application in

generating the electricity from the sun [1] by

converting the light energy absorbed by dyes or

pigments into other electrical energy. The

DSSCs realized the optical absorption and the

charge separation process by the association

of a sensitizer as light-absorbing material with a

wide band gap semiconductor of nano-

crystalline morphology. Photovoltaic properties

of TiO2-ZrO2 cells were measured at different

pH levels and it was expected to utilize the dye

sensitized solar application [2, 3].

In this project, Low cost dye sensitized solar

cell is prepared with henna leaves dye

sensitizer. Two glass slides (photoanode and

carbon electrodes) are offset and two binder

clips are employed to hold the electrodes

together. Photovoltaic properties of TiO2-ZrO2

cell are measured and it is expected to utilize

the dye sensitized solar cells application.

Experimental Procedures

Firstly, the mixed binary oxide TiO2 (BDH

chemicals) (95mol%) - ZrO2 (Analar) (5wt%)

were mixed and it was ground by ball-milling

for 2 h to reduce the particle size. The powder

was separated with 100 mesh, 250 mesh and

400 mesh for the lightest and uniform mixture

powder. Ethnol (C2H5OH) 9 ml was added into

TiO2-ZrO2 mixture powder as a binding agent

and stirred by magnetic stirrer for 2 h to be

homogeneous. Then, it was dried at room

temperature for 24 h and reformed into

homogeneous phase powder. Secondly,

hanna leaves was fabricated as a dye

sensitizer (Fig 1). In addition. The preparation

of the positive and negative electrodes were

built-in soot solution for carbon catalyst

counter electrode (Fig 3) and mediator (Iodine)

(Fig 4). Finally, dye sensitized solar cell is set

by two prepared microscopic glass slides (Fig

2) in the form of sandwiching of the paste of

binding agent, dye sensitizer, electrolyte and

carbon catalyst (Fig 5). Henna leaves pH level

were also measured and DSSC electrical

parameters were evaluated under the

sunlight.

Fig 1. Preparation of dye sensitizer by using Henna leaves

Fig 2. Preparation of microscopic glass

Fig 3 Carbon catalyst on

glass slide

Fig 4. Carbon electric with

Iodine

+

h

gla

ss Dye

gla

ss

_

Counter electrode

Ele

ctr

oly

te

Carb

on c

ata

lyst

Nanocys

talli

ne p

aste

Load

Fig 5. Dye sensitized solar cells (DSSC) application

Introduction

14

5

Results and Discussion

The change in photocurrent as a function of

voltage of TiO2-ZrO2 binary oxide with Henna

leaves dye sensitizer at different pH levels is

presented in Figure 6. The evaluation of some

DSSC parameters, such as conversion

efficiency, fill factor and quantum yield is shown

at Figure 7.

Fig 6. Photocurrent (mA/cm2) – cell voltage (mV) curves of

TiO2-ZrO2 binary oxide with Henna Leaves sensitized

solar cell

Fig 7. The relationship between pH level and efficiency and

fill factor of the cells

Figure 6 shows the relationship between

photocurrent Isc and open-circuit voltage Ioc when

pH level of dye sensitizer keeps on increasing due

to the effect of a typical dye-sensitized solar cell

contains a porous layer of TiO2 nanoparticles

immersed in Henna leaves organic dye. The dye

absorbs the photons from the electromagnetic

waves and converts to the electrical energy, which

flows into the TiO2 nanoparticles. In the figure 7,

the conversion efficiency of the solar cell is

increased.

Conclusion

Growth of TiO2-ZrO2 binary oxide

electrode DSSC with will Henna

Leaves dye sensitizers and low-cost

eco-solar cell properties have been

successfully implemented. The

conversion efficiency was slightly

increased with an increase pH level of

dye sensitizer. The fill factors of all

fabricated cells were observed from

the range of 0.5-0.6 and it is industrial

requirements. Thus it definitely meets

the special requirements for the

development of DSSC for low cost.

Acknowledgement

This project was fully supported by

Department of Physics, Yangon

University, Myanmar (2011-2012). The

author would like to thank to S. Y. Win

and Dr Yin Maung Maung for

experimental assembling the sample

and analysis work.

References

1. Ismael C. Flores., Jilian Nei De

Fretas.,

Claudia Longo., Macro-Aurelio

De Padi, Herbert Winnishofer, and

Ana Flavia Nogueria. (2007),

“Dye-Sensitized solar cells based

on TiO2 nanotubes and a Solid-

State Electrolyte”, Journal of

Photochemistry and Photobiology,

189, p 183-.

2. Chuah, G. K., Jaenicke, S.,

Cheong, S. A., and Chan, K. S.

(1996), “The influence of

preparation conditions on the

surface area of Zirconia”, Journal

of Applied Catalyst, 133, p 267-

3. Dominguez, J., Hernandez, J. L

and Sandoval, G. (2000), “Surface

and catalytic properties of Al2O3-

ZrO2 solid solution prepared bu

sol-gel methods” Journal of

Applied Catalyst”, 197, p119-.

15