ultrasonic tomography gas profiles

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Sensors and ActuatorsB 202 (2014) 4652

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Sensors and Actuators B: Chemical

journa l homepage: www.elsevier .com/ locate /snb

An investigation on chemical bubble column using ultrasonictomography for imaging ofgas profiles

M.H.F. Rahiman a,, R.A. Rahim b,2, H.A. Rahim b,2, E.J. Mohamadc,3, Z. Zakaria a,1,S.Z.M. Muji c

a TomographyImaging and InstrumentationResearch Group, School of Mechatronic Engineering, Universiti Malaysia Perlis, Pauh PutraCampus, 02600

Arau, Perlis, Malaysiab Process Tomographyand Instrumentation Research Group, Faculty of Electrical Engineering, Universiti TeknologiMalaysia, 81310UTMSkudai, Johor,

Malaysiac Faculty of Electrical and Electronic Engineering, Universiti TunHussein OnnMalaysia,86400Batu Pahat, Johor,Malaysia

a r t i c l e i n f o

Article history:

Received 1 March 2014

Received in revised form 1 May 2014

Accepted 12 May 2014

Available online 16 May 2014

Keywords:

Ultrasonic sensor

Tomography

Bubble column

Gas profile

a b s t r a c t

In this paper, we carried out a tomographic investigation ofa chemical bubble column using ultrasonic

sensor. The ultrasonic tomography sensing array was constructed to operate in transceiver-mode and

was clamped on the exterior circumference ofthe column. The time-of-flight and arrival-time analysis

was studied to obtain the signal information. Some experiments were carried out using known static

profiles and were compared with the actual profiles. The findings showed promising results where the

sensing array could detect gas bubble profiles down to 3 mm in diameter, and the conclusionswere made

at the end ofthe paper.

2014 Elsevier B.V. All rights reserved.

1. Introduction

Process tomography is a process of obtaining the plane-section

images of a three-dimensional object. The process tomography

technique produces cross-section images of distribution of com-

ponent flow in a process column, and it offers great potential for

the development and verification of process models and also for

process diagnostic [1,2].

Process tomography hasbecome popular in recent years. Several

tomography imaging technologies have been rapidly developed

to provide solutions and to improve the system performance in

several industries [35]. For instance, in biotechnology industries,

improvement in the reactor performances, for example, in aerobic

fermentationprocesses in order to optimize the oxygen released inthe bioreactor is being researched [6]. This is to ensure optimum

growths of the microbes [7].

Corresponding author. Tel.: +60 4 9885166; fax: +60 4 988 5167.

E-mail addresses:[email protected], [email protected]

(M.H.F. Rahiman), [email protected] (R.A. Rahim), [email protected]

(E.J. Mohamad), [email protected] (Z. Zakaria).1 Tel.: +60 4 9885166, fax: +60 4 988 5167.2 Tel: +60 7 5537801; fax: +60 7 5566177.3 Tel.: +60 7 4537502; fax: +60 7 4536060.

The use of ultrasound is favoured in industries because of its

possibility to perform non-invasive measurement. Besides, ultra-

sound is well established as a popular NDT tool [8,9]. The goal of

ultrasonic tomography is to reconstruct the spatial distribution of

some acoustic parameter of an object using ultrasonic measure-

ments [10,11]. In a tomography process; thefirst step is to generate

the integral measurements using a selected sensor [12]. The next

step is to reconstruct the property field (the cross-sectional distri-

bution of the physical properties of the multiphase media) from

the measured integral values. This process is called tomographic

reconstruction [13].

In this paper, we present an investigation using non-invasive

ultrasonic tomography technique on a chemical bubble column.

The tomography sensor construction will be presented first, fol-lowed by ultrasonic mode of operation. Next, arrival-time analysis

is put forward followed by the transceiver sensing method dis-

cussions. The experiments and results are discussed before the

conclusion sections at the end of the paper.

2. Tomography sensor

It is essential to obtain as much information as possible from

each interrogation in order to construct the best possible image

from the limited number of interrogations [14]. If more sensors are

http://dx.doi.org/10.1016/j.snb.2014.05.043

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M.H.F.Rahiman et al./ Sensors andActuators B 202 (2014) 4652 47

Fig. 1. Sensor array arrangement.

provided, therefore, more measurements can be obtained, which

in turn produced better image quality [15]. To meet this require-

ment, a fan-shaped beam projection was used. A fan-shaped beam

projection allows simultaneous interrogation of a large area. This

ensures maximum number of sensor views located aroundthe col-

umn circumference, which receive the directly transmitted wave.

On the other hand, to further increase the number of mea-

surements a transceiver operation is proposed in this study. In

transceiver operation, each sensor has the ability to transmit and

receive the ultrasonic wave sequentially. This allows interrogation

tobe made from everysensor angle, hence optimizing the measure-

ment numbers. Besides, it may overcome the problem with lowspatial image resolution due to limited projection data [16]. This

may be compared to transmitter-receiver operation, the transmit-

ting and receiving function is dictated by independent transmitter

and receiver sensors as reported in [1719].

The arrangement of the sensor array as illustrated in Fig. 1

consists of 32-ultrasonic sensor positioned 11.25 equally spaced

around the column circumference. Each sensor has transmit and

receive ultrasonic signal capability. When a sensor acts as a trans-

mitter,it projects ultrasonic wavein a fan-shapebeam manner with

a beam angle of 95 and views 17 sensors (act as a receiver) on

the opposite side of the column as shown in Fig. 1. In each scan,

TR1 sensor will start the first projection, followed by TR2 and until

all sensors complete the projection rounds before the next scan

continues and this process takes 16.75ms to complete.

3. Transmission-mode technique

A transmission-mode technique has been proposed and used

in this research. In transmission-mode ultrasonic tomography, the

measurement concerns the amplitude and/or time-of-flight (TOF)

of the received wave, and the assumption of straight-line propaga-

tion is used [19]. Fig. 2 illustrates a transmission to a receiver in a

liquid medium.

In Fig. 2, the transmitter is modelled as a point source which

propagates an ultrasonic wave within an angle in theimageplane

and the receiver is modelled as a circular arc with radius of cur-

vature r. The wavefronts are taken to be circular arcs of uniform

ultrasonic energy. When ultrasound is propagating in the liquid

r

ReceiverTransmitter Gas bubbles

Liquid medium

Fig. 2. Thegas bubblesviewed by an ultrasonic receiver.

Table 1

Comparison of theoretical andmeasured TOF from sensor TR1.

Sensor Distance from

source, TR1 (mm)

Theoretical

TOF (s)

Measured

TOF (s)

TR9 77.78 51.96 58.30

TR10 85.03 56.80 63.00

TR11 91.46 61.10 67.00

TR12 97.01 64.80 68.32

TR13 101.63 67.89 69.00

TR14 105.26 70.31 70.40

TR15 107.89 72.07 71.28

TR16 109.47 73.13 72.70TR17 110.00 73.48 72.75

TR18 109.47 73.13 72.30

TR19 107.89 72.07 71.76

TR20 105.26 70.31 70.20

TR21 101.63 67.89 68.80

TR22 97.01 64.80 67.75

TR23 91.46 61.10 67.00

TR24 85.03 56.80 62.70

TR25 77.78 51.96 57.50

medium, areas occupied by the gas bubbles block the transmitted

waves. As a result, an effect analogous to the shadowing of visible

light by an opaque object occurs.

Consider a single projection is excited from sensor TR1 (Fig. 1);

theactive receivingsensors areTR9TR25. As the distance betweenthe transmitting sensor and the receiving sensor increases, the

ultrasound will have a longer time-of-flight (TOF) to the receiver of

interest. Knowing the speed of sound in the liquid, one can deter-

mine the TOF for each active receiving sensor by measuring its

distancefrom thesource sensor. Forsimplicity, effectof the column

wall is ignored, and the theoretical TOF is compared with the real

measurement. Table 1 tabulates the comparison between the theo-

retical and measured TOFfromsensor TR1and is showngraphically

in Fig. 3.

The TOF obtained from real measurement is slightly elevated

at TR9TR12 and TR22TR25 due to refraction occurred when the

ultrasonic wave penetrates the column wall and liquid medium.

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

TR9 TR10TR11TR12TR13TR14TR15TR16TR17TR18TR19TR20TR21TR22TR23TR24TR25

Time-of-flight(s)

Sensor

Theoretical TOF

Measured TOF

Fig. 3. Theoretical and measured TOF from sensorTR1.


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48 M.H.F.Rahiman et al. / Sensors andActuatorsB 202 (2014) 4652

Fig. 4. Simplified possible transmission paths in the column.

However, the overall trend shows good agreement between the

theoretical and real measurement data.

4. Arrival-timeanalysis

When the component to be imaged is gas bubbles, there maybe no direct transmission path from the transmitting sensor to

the receiving sensor due to the obstacles. The transmitted waves

are reflected on the gas bubble surfaces and the column wall. The

receiving sensor may receive the reflected waves butat a later time

than expected from direct TOF. A direct transmission during non-

gas existence, however, will take the shortest path, which in turn

attains the shortest time [3]. Fig. 4 shows a simplified diagram of

the column with the possible transmission paths.

It is notice that the receiving signals may come from; direct-

transmission (ta), reflected waves by the gas bubble surfaces (tb)

and reflectedwaveson the columnwall (tc).Using Fig.4 asanexam-

ple, the shortest transmission path is the direct transmission (ta).

The reflected waves (tb) and (tc), however, will arrive later. The

delays between each receiving signal are illustrated in Fig. 5.Fig. 5 clearly shows that, it is possible to distinguish the direct

transmission signal with the others. The direct transmission sig-

nal contains the information needed to describe the gas bubble

characteristics.

The greater the difference in acoustic impedance at interfaces,

the greater will be the amount of energy reflected. For the case

of liquid and gas interface, about 99.89% ultrasonic energy will be

reflected [20,21]. Fig. 6 shows a gas bubble with a radius ofa.

A small gas bubbleis definedas a spherewith a radiusofawhere

the circumference of the sphere, 2a, divided by the wavelength of

V

tExcitation Pulses ta tb tc

Receiving signals

Fig. 5. Received signals from three possible transmission paths.

Fig. 6. A gas bubble with radius ofa.

the ultrasound,,ismuchlessthan1asinEquation1 [22]. Knowing

the speed of sound in the liquid, c=f (Eq. (2)) can be simplified to

Eq. (3) where k is the wave number constant [22].

2a

1 (1)

2fa

c 1 (2)

ka 1 (3)where k=2f/cis the wave number,fis the frequency (Hz), cis the

speed of sound (m/s).

When ka1, the scattering is strongly dependent on the parti-

cle size for a given wavelength and in this region, the scattering is

approximately omni-directional, and it is known as Rayleigh scat-

tering [23]. If ultrasonicwaves propagatein a bubbly air/waterwith

a wavelength much shorter than the gas bubbleradius a, i.e.ka1,

the diffraction can be ignored, and these gas bubbles will act as

acoustic opacities [17]. This is because when ka1, the surface

of the sphere appears as a flat surface with respect to the wave-

length and the scattering becomes the same as reflection from a

flat surface.

Based on this approximation, the value ofka=2 can be used as

the minimum value to ignore the diffraction effects in this study.Knowing the speed of sound in water is 1497m/s [24] and resonant

frequency of the sensor is 335 kHz, when ka= 2;

2fa

c = 2 (4)

a =2c

2f (5)

a =2 1497

2 3,35,000 (6)

a = 1.42 mm (7)

Fromthe calculation, thetheoretical resolutionof the gas bubble

is a minimum radius of 1.42mm or 2.84mm in diameter. There-

fore, when the gasbubble diameter is less than 2.84 mm, the sensorcould not sense the profile in the column.

If a gas bubble exists between thetransmission paths,the direct

transmission signal will be attenuated. When a gas bubble with a

diameter ofdg passes within the transmission path, a voltage loss

will occur at Rx. The voltage loss is due to the reflected ultrasonic

wave at the gas bubble boundary. Fig. 7 illustrates the transmitted

and reflected wave when a gas bubble exists in the transmission

path.

In transmission-mode ultrasonic tomography, assumption of a

linear relationship between the gas bubble dimensionand the sen-

sor loss voltage is used [19] where the gas bubble dimension is

proportional to the voltage loss measured at the receiving sensor

[20]. Thus, thegas bubblerelationship in this case canbe estimated

by mathematical expression depicted in Eq. (8).

Vg= Vc Vr (8)

whereVcis the maximum receiver voltage (V), Vris the sensor out-

put voltage (V),Vgis the sensorloss voltage dueto the dggas opacity

(V).

Fig. 7. A simplified ultrasonic transmissionmodel with a gas bubble.


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5. The sensing technique

A usual practice in ultrasonic tomography uses a dedicated

transmitterreceiver pair for sensing the measurement area. Gen-

erally, the spatial resolution of a system depends on the number

of measurement collected. The more measurements taken, the

higheraccuracycan be achieved,whichin turn improves theimage

signal-to-noise ratio (SNR). In order to increase the number of

measurements, a transceiver sensing technique is proposed. In

an ultrasonic tomography system, the sensor array is designed

to ensure optimum coverage of the projection views. Some

researchers use alternate dedicated transmitterreceiver pairs

arranged on the circumference of the column [3,18]. While oth-

ers use fewer projections just enough to cover the measurement

area in order to reduce the processing time [25,26].

In thisresearch32 sensors areused to constructthe tomographic

images. Each transmitting sensor interrogates with 17 receiving

sensors. Using thetransceiver sensing technique,the interrogations

were increased to 544 measurements per scan (32 sensors17

measurements).The projectionis rotated fromsensor TR1 to sensor

TR32 whose transmissionis received by 17 active receivingsensors

on the opposite side of the column. This continues until all sensors

have acted as transmitters and the projection is completed. Fig. 8

shows the transceivers projection paths.

Thedualfunctionsgivethetransceivertechniqueanaddedvalue

since similar numbers of sensors are used to generate a higher

image quality compared to the separate transmitterreceiver

arrangement. In the transceiver technique, when a sensor is set

to be a transmitter, it will be switched to the transmitter circuit.

The same procedure takes place when it is to be set as a receiver; it

will be switched tothe receiver circuit. Thetiming forthe switching

sequence is very important since incorrect switching timing leads

to false synchronization data.

6. Experiments and results

The experimental arrangement and its physical realization are

shown in Figs.9and10, respectively. The sensor array wasmounted

andclamped-on externallyon the column. The connection between

the sensor array and the electronic circuits uses coaxial cables in

order to ensure low noise connections. The electronic circuit com-

prises a mix of analogue and digital processing circuits. The data

from the electronic circuits is conveyed to a personal computer

(PC) using a high-speed RS-232 serial link.

Fig. 8. Transceivers projection paths.

Sensor

array100cm

Electronic circuits

Coaxial

cable

Personal Computer

RS-232

serial link

50cm

Fig. 9. The experimental tomography arrangement.

A number of test profiles were used to simulate gas bubbles and

were placed in the experimental column. The test profile consists

of a hollow capillary made from thin plastic material with both

ends sealed to create air gaps (gas bubble model). Fig. 11 shows

Fig. 10. Photograph of tomography system.


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Fig. 11. Test profile dimensions and their positionsin theexperimental column.

the test profile dimensions and its position in experimental col-

umn. The data was collected, and the tomographic images were

reconstructed using a linear back-projection (LBP) technique. The

reconstructed tomograms in 2D and 3D views are shown in Fig. 12.

All the test profiles could be identified by the tomography

system. The smearing artefacts are quite common due to the back-

projection reconstruction algorithm technique. However, the main

concern in this research is the ability to imaging small gas bub-

bles, which are widely found in chemical columns. The theoretical

detectable gas bubble size as computed previously was 2.8mm in

diameter. To test this limit, a test profile of 3.0 mm diameter was

put in the test (Phantom A), and the results show that the 3.0 mm

diameter profile could be detected by the sensor array. Some

other gas profiles were also used to evaluate the sensor array for


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Fig. 12. Reconstructed test profiles in 2D and 3D views.

imaging sparse gas bubbles, and the results obtained are similar

with the phantoms. The gas bubbles boundaries are clearly seen,

and the position and location in the column are similar with the

test phantoms.

7. Conclusions

Ultrasonic tomography was used to investigate a chemical

bubble column. The sensor array was constructed in transceiver

operating modeto improve the spatial resolution. Some theoretical

calculation was carried out to determine the minimum resolu-

tion of the measurement area. The detectable gas bubble size as

suggested by the theoretical calculation must be 2.84mm in

diameter, though it should be much smaller due to the approxi-

mation used for Eq. (3). A number of 10 test profiles have been

tested on the ultrasonic tomography system with the smallest

test profile of 3.0mm diameter. The results obtained were rea-

sonable where all the reconstructed profiles matched the test


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profiles. The ultrasonic tomography had shown promising results

andtherefore, provides an imaging toolfor chemicalbubble column

investigation.

Acknowledgments

The authors wish to thank Malaysian Government for provid-

ing financial supports under RACE Grant 2013 (9017-00016), RACE

Matching Grant (Q.J130000.3013.00M17), and UTM GUP Grant(03H96).

References

[1] E.J. Mohamad, R.A. Rahim, P.L. Leow, M.H. Fazalul Rahiman, O.M.F. Marwah,N.M. NorAyob, H.A. Rahim, F.R. Mohd Yunus, An introductionof two differen-tial excitationpotentials techniquein electricalcapacitance tomography, Sens.ActuatorsA: Phys. 180 (June)(2012)110.

[2] S. Wckel, U. Hempel, J. Auge, Acousto-capacitive tomography of liquid multi-phase systems, Sens. ActuatorsA: Phys. 172 (December (1)) (2011) 322329.

[3] R.A. Rahim, M.H.F.Rahiman, K.S. Chan, S.W. Nawawi, Non-invasive imaging ofliquid/gas flow using ultrasonic transmission-mode tomography, Sens. Actua-tors A: Phys. 135 (April 2) (2007) 337345.

[4] M. Idroas, R. Abdul Rahim, M.H. Fazalul Rahiman, M.N. Ibrahim, Optical tomo-graphy system based on charge-coupled device linear image sensors: particlesize measurement,Sens. ActuatorsB: Chem. 156 (August (2)) (2011)572577.

[5] H.S.Tapp, A.J.Peyton,E.K. Kemsley,R.H. Wilson, Chemical engineering applica-

tionsof electricalprocesstomography, Sens. Actuators B: Chem.92 (July(12))(2003) 1724.

[6] F. Garcia-Ochoa, E. Gomez, Bioreactor scale-up and oxygen transfer rate inmicrobial processes: an overview, Biotechnol. Adv. 27 (March (2)) (2009)153176.

[7] A. Hocalar, M. Trker, C. Karakuzu, U. Yzgec, Comparison of different estima-tion techniques for biomass concentration in large scale yeast fermentation,ISA Trans.50 (April (2)) (2011) 303314.

[8] H.K. Chai, D.G. Aggelis, S. Momoki, Y. Kobayashi, T. Shiotani,Single-sideaccesstomography forevaluating interior defect of concrete,Constr. Build. Mater.24(December (12)) (2010) 24112418.

[9] M. Thornton, L. Han, M. Shergold, Progress in NDT of resistance spot weldingof aluminium using ultrasonic C-scan, NDT E Int. 48 (June)(2012)3038.

[10] M.H.F. Rahiman, R.A. Rahim, H.A. Rahim, Tomographic reconstruction of amulti-attenuation phantom by means of ultrasonic method, in: J.J. Park, H.-C. Chao, M.S. Obaidat, J. Kim (Eds.), Computer Science and Convergence, vol.114, Springer, Dordrecht, Netherlands, 2012, pp. 761767.

[11] M.H.F. Rahiman,R.A. Rahim, H.A.Rahim, N.M.N. Ayob,E.J. Mohamad,Z. Zakaria,

Modellingultrasonic sensorfor gasbubble profiles characterization ofchemicalcolumn, Sens. ActuatorsB: Chem. 184 (July)(2013)100105.[12] R. Abdul Rahim, L.C. Leong, K.S. Chan, M.H. Rahiman, J.F. Pang, Real time mass

flowrate measurement usingmultiplefan beamopticaltomography, ISA Trans.47 (January (1)) (2008) 314.

[13] P. Munshi, Computerized tomography for scientists and engineers, CRC, BocaRaton,FL, London, 2007.

[14] C. Yan, J. Zhong, Y. Liao, S. Lai, M. Zhang, D. Gao, Design of an applied opticalfiber process tomography system, Sens. Actuators B: Chem. 104 (January (2))(2005) 324331.

[15] C. Yan, Y. Liao, Design of a new optical fiber process tomography configura-tion with high image reconstruction resolution, Sens. Actuators B: Chem. 186(September) (2013) 186192.

[16] K.J. Batenburg, L. Plantagie, Fast approximation of algebraic reconstructionmethods for tomography, IEEE Trans. Image Process. 21 (August (8)) (2012)36483658.

[17] L.-J. Xu, L.-A. Xu, Ultrasound tomography system used for monitoring bubblygas/liquid two-phase flow, IEEE Trans. Ultrason. Ferroelectr. Freq. Control 44(1) (1997) 6776.

[18] M.D. Supardan, Y. Masuda, A. Maezawa, S. Uchida, The investigation of gasholdup distributionin a two-phasebubblecolumnusing ultrasonic computedtomography, Chem. Eng. J. 3 (June) (2007) 125133.

[19] M.H.F.Rahiman,R.A. Rahim,M. Tajjudin, Ultrasonic transmission-mode tomo-graphy imaging for liquid/gas two-phase flow, Sens. J. IEEE 6 (December (6))(2006) 17061715.

[20] M.H.F. Rahiman, R.A. Rahim, H.A. Rahim, Gas hold-up profiles measurementusing ultrasonic sensor, Sens. J. IEEE 11 (February (2)) (2011) 460461.

[21] M.H.F. Rahiman, R.A. Rahim, Z. Zakaria, Design and modelling of ultrasonictomography fortwo-component high-acousticimpedancemixture, Sens. Actu-ators A: Phys. 147 (October (2)) (2008) 409414.

[22] C.M. Otto, The Practice of Clinical Echocardiography, Elsevier/Saunders,Philadelphia, PA, 2012.

[23] P. Shull, B. Tittmann,Ultrasound,in: NondestructiveEvaluation, CRCPress,USA,2002.

[24] J.D.N. Cheeke, Fundamentals and Applications of Ultrasonic Waves, CRC Press,Boca Raton,2012.

[25] L.J. Xu, L.A. Xu, Gas/liquid two-phase flow regime identification by ultrasonictomography, Flow Meas. Instrum. 4 (April) (1998) 145155.

[26] L. Xu, Y. Han, L.-A. Xu, J. Yang, Application of ultrasonic tomography to moni-toring gas/liquid flow, Chem. Eng. Sci. 52 (July (13)) (1997) 21712183.

Biographies

M.H.F. Rahimanreceived B.Eng.(Hons)degree in electrical(controland instrumen-tation), M. Eng. and Ph.D.degree in electrical engineering fromUniversiti TeknologiMalaysia (UTM), Johor, Malaysia, in 2003, 2005, and 2013 respectively. In 2006, he

joined Universiti Malaysia Perlis (UniMAP), Perlis, Malaysia, as a teaching staff mem-

ber and at present he holds senior lecturer position. His research interests includeprocess tomography, sensors and instrumentations.

R.A. Rahim received B.Eng. degree with Honours in Electronic System and ControlEngineering in 1992 from Sheffield City Polytechnic, UK. He received his Ph.D. inInstrumentation & Electronics Engineering from Sheffield Hallam University, UK in1996. At present he is a Professor and a Director of Research Management Centre,Universiti Teknologi Malaysia. His current research interests are process tomogra-phy and sensor technology.

H.A.Rahim receiveda B.Engin ElectricalEngineering (Controland Instrumentation)andM.Engin ElectricalEngineeringfrom Universiti TeknologiMalaysiain 1998 and2000, respectively. She received her Ph.D in Electrical Engineering from UniversitiTeknologi MARA, in 2009. At present she is an Associate Professor at Faculty ofElectrical Engineering, UniversitiTeknologi Malaysia. Hercurrent researchinterestsare sensor technology and artificial intelligent system. She is a senior member ofthe IEEE, a Professional Engineer, Board of Engineers Malaysia (BEM), a corporatememberof theInstitute of EngineersMalaysia (IEM) and CharteredEngineer of theInstitute of Engineering and Technology.

E.J.Mohamadreceivedher B.Eng.degreewith honours in instrumentation andcon-trol in 2000 from Universiti Tun Hussien Onn Malaysia, MEng and Ph.D. degreein Electrical Engineering from Universiti Teknologi Malaysia in 2005 and 2012respectively. She is currently a teaching staff member at Universiti Tun HussienOnn Malaysia. Her research interestsinclude process tomography, sensors, processcontrol and instrumentations.

Z. Zakaria received his Master of Engineering in Electrical-Electronics & Telecom-munication Engineering in 2007 at Universiti Teknologi Malaysia (UTM). He iscurrently a Ph.D. student at the same university under Faculty of Electrical Engi-neering. His main research area is in tomography which is focusing in MagneticInduction Tomography application in low conductivity material imaging.

S.Z.M. Muji received her M.Sc. degree in Electric and Electronic Engineering fromUniversiti Sains Malaysia in 2004 andhis PhD degreein Electronic Instrumentationat UniversitiTeknologi Malaysia in 2012.She is currentlya senior lecturer at theFac-ulty of Electric and Electronic Engineering at Universiti Tun Hussein Onn Malaysia,focusing on Optical Tomography and embedded system application.
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