**Professor Boonchai Techaumnat, Ph.D.**

### ศ. ดร.บุญชัย เตชะอำนาจ

**Education**

- Ph.D. (Electrical Engineering), Kyoto University, Japan, 2001
- M.Eng. (Electrical Engineering), Chulalongkorn University, Thailand, 1995
- B.Eng. (Electrical Engineering), Chulalongkorn University, Thailand, 1990

**Email:** Boonchai.T@chula.ac.th

**Research Interest**

- High-voltage engineering
- Transmission-line technologies
- Numerical field analysis
- Particle Electromechanics
- Bioelectromagnetics
- Micro-Nano engineering
- Lab-on-a-Chip / Microfluidics

**Research Cluster**

**Link to**

Techaumnat, B; Panklang, N

Electromechanical Analysis of Red Blood Cell under AC Electric Field Journal Article

In: IEEE Transactions on Magnetics, vol. 57, no. 6, 2021, ISSN: 00189464, (cited By 0).

@article{Techaumnat2021,

title = {Electromechanical Analysis of Red Blood Cell under AC Electric Field},

author = {B Techaumnat and N Panklang},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85103277516&doi=10.1109%2fTMAG.2021.3067353&partnerID=40&md5=3f10f2c67f6274bfddb63db361ee51fd},

doi = {10.1109/TMAG.2021.3067353},

issn = {00189464},

year = {2021},

date = {2021-01-01},

journal = {IEEE Transactions on Magnetics},

volume = {57},

number = {6},

publisher = {Institute of Electrical and Electronics Engineers Inc.},

abstract = {This article presents the numerical analysis of electromechanics of a red blood cell under electric field in a microchannel. We use 3-D computation to study the dielectrophoretic (DEP) characteristics of the cell subjected to electric field generated by parallel planar electrodes. The aim of this work is to investigate the variation in electric field frequency of the DEP force on the cell in different orientations and to clarify cell behavior during the transition between the positive and negative dielectrophoresis, which is important for on-chip cell manipulation. We use the boundary element method and apply the boundary condition of transmembrane potential on the cell membrane for calculation. The simulation results show that the DEP characteristics depend highly on the orientation and the position of the cell from electrode edge. The vertical and horizontal DEP forces change their directions at different values of field frequency. The re-orientation of red blood cells observed in the experiment is related to the calculated DEP behavior. © 1965-2012 IEEE.},

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Nantanawut, W; Techaumnat, B; Tanthanuch, N

Numerical Simulation of the Disintegration of an Aqueous Drop under Electric Field Journal Article

In: IEEE Transactions on Magnetics, vol. 57, no. 6, 2021, ISSN: 00189464, (cited By 0).

@article{Nantanawut2021,

title = {Numerical Simulation of the Disintegration of an Aqueous Drop under Electric Field},

author = {W Nantanawut and B Techaumnat and N Tanthanuch},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85103913210&doi=10.1109%2fTMAG.2021.3070808&partnerID=40&md5=b3e3c6215612dbedc4c40b40a7f71bce},

doi = {10.1109/TMAG.2021.3070808},

issn = {00189464},

year = {2021},

date = {2021-01-01},

journal = {IEEE Transactions on Magnetics},

volume = {57},

number = {6},

publisher = {Institute of Electrical and Electronics Engineers Inc.},

abstract = {Electrocoalescence is an industrial application of high voltage for separating an aqueous phase from an oil phase using electric field to promote the aggregation of aqueous drops. The thickness of the oil film between drops decreases and ruptures. As a consequence, the drops coalesce together. However, if the electric field is too high, the resultant drop deforms and disintegrates, reducing the efficiency of the electrocoalescence process. In this work, a multiple-physic simulation is performed to determine the critical electric field that causes the disintegration of an aqueous drop. The configuration is an aqueous drop, located on a grounded electrode in an insulating oil under an electric field. We numerically analyze the deformation and disintegration of a drop under the applied electric field using the finite element method. We use the level set method to track the interface between the aqueous drop and the insulating oil. The results show that the aqueous drop elongates due to the electric force and starts to deform under 0.36 kV/mm electric field. The elongation and the deformation of drop increase with the electric field. Eventually, the aqueous drop completely loses its stability at the critical field value, which is equal to 0.9 kV/mm. An experiment is conducted to observe the disintegration of drop. The experimental results demonstrate that the drop disintegration occurs at the average electric field of 1.02 kV/mm, slightly higher than the critical field obtained from the simulation. © 1965-2012 IEEE.},

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Matra, K; Buppan, P; Techaumnat, B

In: Applied Sciences (Switzerland), vol. 10, no. 12, 2020, ISSN: 20763417, (cited By 0).

@article{Matra2020,

title = {Analytical and experimental studies on the application of a series of treatment chambers for Escherichia coli inactivation by pulsed electric fields},

author = {K Matra and P Buppan and B Techaumnat},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087379114&doi=10.3390%2fAPP10124071&partnerID=40&md5=2939e44c09eaf9ea9b702254509f2179},

doi = {10.3390/APP10124071},

issn = {20763417},

year = {2020},

date = {2020-01-01},

journal = {Applied Sciences (Switzerland)},

volume = {10},

number = {12},

publisher = {MDPI AG},

abstract = {The paper investigated studies on the application of pulsed electric fields for the treatment of liquid media in a continuous manner in a co-field treatment chamber with elliptic insulator profiles. The electric field distribution and the temperature rise in the treatment chamber were evaluated via the finite element method. A non-uniform electric field was found at the elliptical insulator edges, while the electric field distribution on the insulator surface was rather uniform. The maximum temperature rise in the liquid media was located slightly behind the elliptic insulator due to the accumulated heat in the flowing liquid media. In the optimized treatment chamber, the average electric field intensity could be as high as 12.21 kV/cm at the moderate voltage at 7.5 kV. As a strategy to improve the inactivation while limiting the temperature rise, a series of treatment chambers was verified by experiments under the conditions of 7.5 kV, a 2.5% duty cycle, and 250 Hz. It was found that an increase in the treatment units could increase the inactivation efficiency for Escherichia coli. The average log reduction could be improved from 1.82 to 2.39 when the number of treatment units was increased from 1 to 5, respectively. © 2020 by the authors.},

note = {cited By 0},

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Techaumnat, B; Panklang, N; Wisitsoraat, A; Suzuki, Y

Study on the discrete dielectrophoresis for particle–cell separation Journal Article

In: Electrophoresis, vol. 41, no. 10-11, pp. 991-1001, 2020, ISSN: 01730835, (cited By 3).

@article{Techaumnat2020,

title = {Study on the discrete dielectrophoresis for particle–cell separation},

author = {B Techaumnat and N Panklang and A Wisitsoraat and Y Suzuki},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85080119008&doi=10.1002%2felps.201900473&partnerID=40&md5=fd4db5072ee94edf79a34b55b48ffe7b},

doi = {10.1002/elps.201900473},

issn = {01730835},

year = {2020},

date = {2020-01-01},

journal = {Electrophoresis},

volume = {41},

number = {10-11},

pages = {991-1001},

publisher = {Wiley-VCH Verlag},

abstract = {This paper presents the application of the discrete dielectrophoretic force to separate polystyrene particles from red blood cells. The separation process employs a simple microfluidic device that is composed of interdigitated electrodes and a microchannel. The discrete dielectrophoretic force is generated by adjusting the duty cycle of the applied voltage. The electrodes make a tilt angle with the microchannel to change the moving direction of the red blood cells. By adjusting the voltage magnitude and duty cycle, we investigate the deflection of red blood cells and the variation of cell velocity along electrode edge under positive dielectrophoresis. The experiments with polystyrene particles show that the enrichment of the particles is greater than 150 times. The maximum separation efficiency is 97% for particle-to-cell number ratio equal to 1:2000 in the sample having high cell concentration. Using the appropriate applied voltage magnitude and duty cycle, the discrete dielectrophoretic force can prevent the clogging of microchannel while successfully separating the particles from the cells with high enrichment and efficiency. The proposed principle can be readily applied to dielectrophoresis-based devices for biomedical sample preparation or diagnosis such as the separation of rare or infected cells from a blood sample. © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim},

note = {cited By 3},

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Panklang, N; Techaumnat, B; Wisitsoraat, A

Analysis of the equivalent dipole moment of red blood cell by using the boundary element method Journal Article

In: Engineering Analysis with Boundary Elements, vol. 112, pp. 68-76, 2020, ISSN: 09557997, (cited By 2).

@article{Panklang2020,

title = {Analysis of the equivalent dipole moment of red blood cell by using the boundary element method},

author = {N Panklang and B Techaumnat and A Wisitsoraat},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077062551&doi=10.1016%2fj.enganabound.2019.12.002&partnerID=40&md5=4f88585a374d16d2308e83ff6b5fc71c},

doi = {10.1016/j.enganabound.2019.12.002},

issn = {09557997},

year = {2020},

date = {2020-01-01},

journal = {Engineering Analysis with Boundary Elements},

volume = {112},

pages = {68-76},

publisher = {Elsevier Ltd},

abstract = {Equivalent dipole moment of biological cells under electric field is an important parameter for various applications such as analysis and manipulation of cells in biomedical samples. The dipole moment depends on cell geometries as well as electrical parameters of media involved. Unfortunately, the analytical expression of equivalent dipole is available only for simple geometries. This work numerically studies the variation of the dipole moment of a red blood cell with cell geometries and electrical parameters. The cell is modelled as a sphere, an oblate spheroid or a biconcave disc. The authors apply the boundary element method to electric field calculation and use re-expansion formulae to compute the equivalent dipole moment of the cell. The numerical results agree well with the analytical one for the spherical model. The effects of cell geometries are clarified for two directions of the electric field, which are parallel or normal to the axis of symmetry of the cell. Using the biconcave disc model, we perform iterative calculation to estimate the intracellular conductivity and specific membrane capacitance of red blood cells from experimental results. © 2019 Elsevier Ltd},

note = {cited By 2},

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Techaumnat, B; Huynh, V Q; Hidaka, K

Numerical Analysis and Experiments on the Electromechanical Behavior of Wired-Shape Conducting Particles Journal Article

In: IEEE Transactions on Magnetics, vol. 54, no. 3, 2018, ISSN: 00189464, (cited By 1).

@article{Techaumnat2018,

title = {Numerical Analysis and Experiments on the Electromechanical Behavior of Wired-Shape Conducting Particles},

author = {B Techaumnat and V Q Huynh and K Hidaka},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028968808&doi=10.1109%2fTMAG.2017.2734742&partnerID=40&md5=862c635ca4b7d1590873bc1a85ab7ec1},

doi = {10.1109/TMAG.2017.2734742},

issn = {00189464},

year = {2018},

date = {2018-01-01},

journal = {IEEE Transactions on Magnetics},

volume = {54},

number = {3},

publisher = {Institute of Electrical and Electronics Engineers Inc.},

abstract = {This paper presents the numerical analysis and experiments on the electromechanical behavior of conducting wired-shape particles. We investigate the effects of particle ending profiles and orientation on the initial motion. The boundary element method is used to analyze the electric field, forces, and torques on the particles. The calculated liftoff electric field is smaller than the estimated value based on a model of infinitely long cylinder, and slightly decreases for a particle with a sharp end when the sharp tip is separated from the electrode. The measured liftoff electric field agrees with the tendency obtained from the numerical analysis. Particles mostly began the motion at either end. When the sharp tip was separated from the electrode, the initial motion almost exclusively took place at the sharp end. On the other hand, the probability was slightly higher for the motion at the rounded end when the sharp tip was close to the electrode. The numerical calculation clarifies that the electrostatic and gravitational torques contribute to such liftoff behavior. © 2017 IEEE.},

note = {cited By 1},

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Sangsri, T; Techaumnat, B

Experimental study on the movement of non-spherical particles in nonuniform electric field Journal Article

In: IEEE Transactions on Dielectrics and Electrical Insulation, vol. 24, no. 2, pp. 861-868, 2017, ISSN: 10709878, (cited By 3).

@article{Sangsri2017,

title = {Experimental study on the movement of non-spherical particles in nonuniform electric field},

author = {T Sangsri and B Techaumnat},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018736746&doi=10.1109%2fTDEI.2017.006225&partnerID=40&md5=924d467ac81deef7a7dbdd9ad8fecb51},

doi = {10.1109/TDEI.2017.006225},

issn = {10709878},

year = {2017},

date = {2017-01-01},

journal = {IEEE Transactions on Dielectrics and Electrical Insulation},

volume = {24},

number = {2},

pages = {861-868},

publisher = {Institute of Electrical and Electronics Engineers Inc.},

abstract = {The deactivation of free particles is an important issue for improving the insulating capability and reliability of high-voltage systems. In this work, we carry out experiments to investigate the electromechanical behavior of the non-spherical conducting particles for different particle orientations on either bare or coated electrode. Spheroidal and wire-shaped particles are used for the experiments. The particle motion is observed for two principal orientations with respect to the applied electric field in air. The results show that on a bare electrode, both kinds of particles exhibit the liftoff motion when the particle axis is aligned with electric field gradient. The field nonuniformity enhances the upward rotation of the particle tip subjected to the higher electric field. When the particle axis is parallel with a constant field line, the wire-shaped particle is more readily to make a rolling motion to the region of stronger electric field in comparison with the spheroidal particle, which shows higher occurrence rate of liftoff. The motion onset electric field decreases with increasing field nonuniformity. On the insulated electrode, the wire-shaped particle shows exclusively the rolling motion, whereas the spheroidal particle may make a rolling motion or rotate horizontally so as to align its axis with electric field gradient. © 2017 IEEE.},

note = {cited By 3},

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Techaumnat, B; Matsusaka, S

Effect of charge transfer on electrostatic adhesive force under different conditions of particle charge and external electric field Journal Article

In: Powder Technology, vol. 301, pp. 153-159, 2016, ISSN: 00325910, (cited By 11).

@article{Techaumnat2016,

title = {Effect of charge transfer on electrostatic adhesive force under different conditions of particle charge and external electric field},

author = {B Techaumnat and S Matsusaka},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973386991&doi=10.1016%2fj.powtec.2016.06.008&partnerID=40&md5=cc93ce0503fa7a4919b1ef54987f6ba6},

doi = {10.1016/j.powtec.2016.06.008},

issn = {00325910},

year = {2016},

date = {2016-01-01},

journal = {Powder Technology},

volume = {301},

pages = {153-159},

publisher = {Elsevier B.V.},

abstract = {The electrostatics of charged particles are utilized for various applications. This paper presents an analysis of the electric field and electrostatic adhesive force on a charged dielectric particle lying on a conducting plane under an externally applied electric field. The purpose of the analysis is to quantitatively investigate the force variation when there is charge transfer between the particle and the conducting plane. We treat the distribution of charges as either uniform on the particle or partially on the lower half. The transferred charge density is assumed to be dependent on the applied electric field. The results show that the electric field is very strong near the contact point, where the charge transfer may occur. Without the charge transfer, the electrostatic adhesive force on a negatively charged particle increases when the applied field is in the upward direction from the plane. However, in the presence of charge transfer, the force may vary only slightly with the applied field or even show a reverse tendency if the transfer charge density depends significantly on the applied field. © 2016 Elsevier B.V..},

note = {cited By 11},

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Sangsri, T; Techaumnat, B; Huynh, V Q; Hidaka, K

Experimental study on the motions of prolate spheroidal particles under electric field Journal Article

In: IEEE Transactions on Dielectrics and Electrical Insulation, vol. 23, no. 5, pp. 2626-2632, 2016, ISSN: 10709878, (cited By 4).

@article{Sangsri2016,

title = {Experimental study on the motions of prolate spheroidal particles under electric field},

author = {T Sangsri and B Techaumnat and V Q Huynh and K Hidaka},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84997831825&doi=10.1109%2fTDEI.2016.7736820&partnerID=40&md5=091a37e78c5bf38e6ca92f60346f7beb},

doi = {10.1109/TDEI.2016.7736820},

issn = {10709878},

year = {2016},

date = {2016-01-01},

journal = {IEEE Transactions on Dielectrics and Electrical Insulation},

volume = {23},

number = {5},

pages = {2626-2632},

publisher = {Institute of Electrical and Electronics Engineers Inc.},

abstract = {This paper presents a study on the electromechanics of prolate spheroidal conducting particles on a conducting plane. The objective of the study is to clarify the fundamental role of the non-spherical shape of particles on their behavior under electric field. We used two sizes of particles having the same major axial length but different diameter (minor axes) for the experiments. The electric field EM initiating particle motion was measured, and we found that EM was slightly higher than the theoretical field strength of the particle for rotation. The lift-off behavior of the particles at EM was different from the theoretical prediction as the particles departed from the conducting plane at significantly larger angles than the theoretical prediction. The discrepancy of the departing angle was possibly due to the predominant rotating motion of particles. With higher electric field than EM, the experimental results showed that the linear vertical motion of particles became dominant, resulting in virtually parallel lift-off of the particles. However, re-contact might occur after lift-off between the particles and the lower electrode, and increase the particle charge as a result. Charge estimation based on the lying cylindrical model is found appropriate only when a particle has a small aspect (length-to-diameter) ratio or when the field is much higher than the critical field for particle rotation. © 2016 IEEE.},

note = {cited By 4},

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Tonapan, T; Panklang, N; Techaumnat, B; Tuantranont, A

Experimental study on breakdown behavior and vacuole isolation of protoplasts under electrical pulses Journal Article

In: IEEE Transactions on Dielectrics and Electrical Insulation, vol. 23, no. 4, pp. 2492-2498, 2016, ISSN: 10709878, (cited By 1).

@article{Tonapan2016,

title = {Experimental study on breakdown behavior and vacuole isolation of protoplasts under electrical pulses},

author = {T Tonapan and N Panklang and B Techaumnat and A Tuantranont},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84986907275&doi=10.1109%2fTDEI.2016.7556529&partnerID=40&md5=ae9cdbdf4ce13b3b2d8f6a2269aefc03},

doi = {10.1109/TDEI.2016.7556529},

issn = {10709878},

year = {2016},

date = {2016-01-01},

journal = {IEEE Transactions on Dielectrics and Electrical Insulation},

volume = {23},

number = {4},

pages = {2492-2498},

publisher = {Institute of Electrical and Electronics Engineers Inc.},

abstract = {This paper presents the experiments on the breakdown behavior of plant protoplasts under electrical pulses. A microfabricated device was utilized for facilitating single-cell observation and for patterning the electric field distribution that enhanced the efficiency of membrane charging. The objectives of the work are to study the effects of pulse parameters on the breakdown behavior and to investigate the use of electric pulses for vacuole isolation. We observed the breakdown behavior of the protoplasts, prepared from butterfly pea, by applying sinusoidal electric pulses to activate the membrane breakdown. The pulse frequency was varied from 20 kHz to 1 MHz and the pulsing duration was between 1 and 100 ms. The experimental results exhibited two kinds of the breakdown behavior under electric field. That is, the breakdown took place on both cell membrane and tonoplast (vacuolar membrane), or the breakdown was limited only to the cell membrane. The probability of cell-membrane breakdown increased with longer pulsing duration or lower pulse frequency. The probability of vacuole isolation also varied with the pulse frequency and duration. Our results show that efficient vacuole isolation can be achieved by using a pulse frequency close to the characteristic frequency of membrane charging for an appropriate pulsing duration. © 1994-2012 IEEE.},

note = {cited By 1},

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Techaumnat, B; Huynh, V; Hidaka, K

Three-dimensional electromechanical analysis of a conducting prolate spheroid on a grounded plane Journal Article

In: IEEE Transactions on Dielectrics and Electrical Insulation, vol. 21, no. 1, pp. 80-87, 2014, ISSN: 10709878, (cited By 2).

@article{Techaumnat2014,

title = {Three-dimensional electromechanical analysis of a conducting prolate spheroid on a grounded plane},

author = {B Techaumnat and V Huynh and K Hidaka},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897680901&doi=10.1109%2fTDEI.2013.004294&partnerID=40&md5=b442a19154d0edf79fb6174f31d48af3},

doi = {10.1109/TDEI.2013.004294},

issn = {10709878},

year = {2014},

date = {2014-01-01},

journal = {IEEE Transactions on Dielectrics and Electrical Insulation},

volume = {21},

number = {1},

pages = {80-87},

publisher = {Institute of Electrical and Electronics Engineers Inc.},

abstract = {This paper presents a 3D analysis of the electromechanics for a conducting prolate spheroid on a grounded plane under electric field. The objective of the analysis is to clarify the roles of tilt angle α between the particle and the plane on the electrostatic force and torque on the spheroid, which are the fundamentals of particle behavior in various applications. The method of multipole images and multipole re-expansion for the prolate spheroidal coordinates are applied to electric field calculation. The electrostatic force and torque on the spheroid are then determined. The calculation results show that the maximal field takes place at or near the higher pole of the spheroid for nonzero tilt angles. The electrostatic force is minimal and maximal when the spheroid lies and stands on the plane, respectively. We present empirical formulae for estimating the minimal and maximal force with error smaller than 1% for the major-to-minor axis ratio between 1 and 10. The electrostatic torque is in the increasing α direction, and it is magnified with increasing α from 0 to about 45°, and then reduces to zero at α = 90°. The torque variation may be estimated by a quadratic relationship. When the gravitational force of the particle is taken into account, the electromechanical behavior can be classified into three regimes, depending on the externally applied field and the tilt angle. The presence of the electrostatic torque enhances the probability of a spheroid particle to be lifted from the grounded plane by the electric field. © 2014 IEEE.},

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Techaumnat, B

Numerical analysis of DC-field-induced transmembrane potential of spheroidal cells in axisymmetric orientations Journal Article

In: IEEE Transactions on Dielectrics and Electrical Insulation, vol. 20, no. 5, pp. 1567-1576, 2013, ISSN: 10709878, (cited By 5).

@article{Techaumnat2013,

title = {Numerical analysis of DC-field-induced transmembrane potential of spheroidal cells in axisymmetric orientations},

author = {B Techaumnat},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84887040000&doi=10.1109%2fTDEI.2013.6633685&partnerID=40&md5=154c7fc3d1746d1880ba7e3a1f07c824},

doi = {10.1109/TDEI.2013.6633685},

issn = {10709878},

year = {2013},

date = {2013-01-01},

journal = {IEEE Transactions on Dielectrics and Electrical Insulation},

volume = {20},

number = {5},

pages = {1567-1576},

abstract = {This paper presents the electrostatic analysis of direct-current and steady-state transmembrane potential of non-spherical biological cells. The purpose of this analysis is to clarify the influences of different cell geometries and conductivity of the extracellular medium on transmembrane potential. The cells are modeled as spherical or spheroidal and as having different ratios between the radii in different axial directions. The boundary element method, a numerical method, is applied to the calculation of the transmembrane potential. The calculations show that a decrease in the conductivity affects both magnitude and distribution of transmembrane potential. The cell membrane can be approximated as a perfect dielectric, provided that the conductivity of the extracellular medium is sufficiently high. For the same cell geometries, transmembrane potential is smaller for pairs of cells than for isolated cells, and this potential is more reduced at the contact poles than at the opposite poles. Either different axial lengths or different radii between the cells results in this disparity in transmembrane potential of the cell pair. However, the maximum potential of both cells approaches the same value and is located at the contact poles if the conductivity in the extracellular medium is very low. © 1994-2012 IEEE.},

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Washizu, M; Techaumnat, B

Analysis of general multipolar images on dielectric layers for the calculation of DEP force Journal Article

In: Journal of Electrostatics, vol. 71, no. 5, pp. 854-861, 2013, ISSN: 03043886, (cited By 1).

@article{Washizu2013,

title = {Analysis of general multipolar images on dielectric layers for the calculation of DEP force},

author = {M Washizu and B Techaumnat},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84880619421&doi=10.1016%2fj.elstat.2013.06.010&partnerID=40&md5=968ae36069f1895da99425e46453f51f},

doi = {10.1016/j.elstat.2013.06.010},

issn = {03043886},

year = {2013},

date = {2013-01-01},

journal = {Journal of Electrostatics},

volume = {71},

number = {5},

pages = {854-861},

abstract = {An axisymmetric field problem of a sphere and a multi-layered planer dielectric body is investigated based on the multipolar expansion method. First, the multipolar potential, produced by the sphere and expressed in the spherical coordinate system, is re-written in the cylindrical coordinate system as an integral of Bessel function. Then the field problem is solved with the boundary conditions at the planer interface of the dielectrics, and the obtained potential is written back to spherical harmonics, which can be regarded as "image multipoles" inside the dielectric body. The "images" influences back the "multipoles" on the sphere, and the field can be determined by solving these relations in self-consistent manner. DEP force exerted on the particle is calculated as the multipolar interaction, as well as the capacitance for the case involving a conducting sphere and a conducting plane. © 2013 Elsevier B.V.},

note = {cited By 1},

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Phansiri, N; Techaumnat, B

Study on the electromechanics of a conducting particle under nonuniform electric field Journal Article

In: IEEE Transactions on Dielectrics and Electrical Insulation, vol. 20, no. 2, pp. 488-495, 2013, ISSN: 10709878, (cited By 16).

@article{Phansiri2013,

title = {Study on the electromechanics of a conducting particle under nonuniform electric field},

author = {N Phansiri and B Techaumnat},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84877302011&doi=10.1109%2fTDEI.2013.6508751&partnerID=40&md5=2589d337bba64197ef6766e77cd84f44},

doi = {10.1109/TDEI.2013.6508751},

issn = {10709878},

year = {2013},

date = {2013-01-01},

journal = {IEEE Transactions on Dielectrics and Electrical Insulation},

volume = {20},

number = {2},

pages = {488-495},

abstract = {This paper presents the study on the electromechanics of a conducting particle under nonuniform electric field between nonparallel electrodes. The purpose of the study is to investigate the feasibility of particle manipulation by the dielectrophoretic (DEP) force for insulation systems. A numerical simulation of the particle motion under electric field has been carried out to clarify the particle behavior without the application of particle manipulating technique. The results show that the charged particle moves to the region of lower electric field (wider gap), and the displacement increases with the tilt angle between the electrodes. The experimental measurement of the particle displacement agrees with the numerical results. For particle manipulation, the dielectric layers of silicone rubber and polyimide are placed on the grounded electrode. Numerical field calculation shows that with the dielectric layers, the DEP force attracts the particle to the region of higher field (smaller gap) and immobilizes it at the termination of the dielectric layers. Experiments are carried out to verify the theoretical prediction. © 1994-2012 IEEE.},

note = {cited By 16},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Huynh, V Q; Techaumnat, B; Hidaka, K

Analysis on electrostatic behavior of a conducting prolate spheroid under an electric field Journal Article

In: IEEE Transactions on Dielectrics and Electrical Insulation, vol. 20, no. 6, pp. 2230-2238, 2013, ISSN: 10709878, (cited By 8).

@article{Huynh2013a,

title = {Analysis on electrostatic behavior of a conducting prolate spheroid under an electric field},

author = {V Q Huynh and B Techaumnat and K Hidaka},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897732525&doi=10.1109%2fTDEI.2013.6678874&partnerID=40&md5=9974257d882c630ce35e24a6b7ca1fb2},

doi = {10.1109/TDEI.2013.6678874},

issn = {10709878},

year = {2013},

date = {2013-01-01},

journal = {IEEE Transactions on Dielectrics and Electrical Insulation},

volume = {20},

number = {6},

pages = {2230-2238},

publisher = {Institute of Electrical and Electronics Engineers Inc.},

abstract = {This paper presents the electrostatic analysis of a conducting prolate spheroid under an external electric field in axisymmetric configurations. The configurations consist of a conducting spheroid which is in contact with or separated from a grounded plane. We apply the method of images using multipoles to the electric field calculation. The calculation uses the multipole re-expansion formulae and the equivalent image charges of a prolate conducting spheroid. The induced charge and force are determined from the multipole images. For a spheroid on the grounded plane, the calculation results show that the maximal field increases nonlinearly with the major-to-minor axis ratio of the spheroid. The charge and the force are compared between the spheroids of the same major axis or the same surface area. We propose empirical formulae for approximating the maximal field, charge and force with the errors smaller than 2% for the axis ratio between 1 and 32. We examine the propriety of the approximation of the electric field, charge and force based on a hemispheroidal model. For an uncharged spheroid separated from the grounded plane, we clarify the relationship between the separation and the field intensification at the bottom pole of the spheroid. Based on the critical field strength of a background medium, the position of the spheroid where the partial discharge takes place is estimated. For a charged spheroid, we found that the maximal electric field hardly depends on the separation from the plane. © 2013 IEEE.},

note = {cited By 8},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Techaumnat, B; Takuma, T

Electric field analysis using image charges of spheroidal harmonics and its application to the calculation of field in cavities Journal Article

In: IEEE Transactions on Dielectrics and Electrical Insulation, vol. 19, no. 6, pp. 2165-2175, 2012, ISSN: 10709878, (cited By 0).

@article{Techaumnat2012,

title = {Electric field analysis using image charges of spheroidal harmonics and its application to the calculation of field in cavities},

author = {B Techaumnat and T Takuma},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84872153913&doi=10.1109%2fTDEI.2012.6396977&partnerID=40&md5=9f68f2bda304f9c800e6ad05809032a4},

doi = {10.1109/TDEI.2012.6396977},

issn = {10709878},

year = {2012},

date = {2012-01-01},

journal = {IEEE Transactions on Dielectrics and Electrical Insulation},

volume = {19},

number = {6},

pages = {2165-2175},

abstract = {This paper describes a method of electric field analysis for configurations consisting of oblate spheroidal objects. In the method, electric potential is expressed as a sum of oblate spheroidal harmonics. The method utilizes the re-expansion and the image schemes of a dielectric oblate spheroid and a conducting plane to determine the solution of potential that satisfies all the boundary conditions involved. Electric field is calculated for an oblate spheroidal void enclosed in a solid dielectric near an electrode. The object of the calculation is to clarify the electric field inside the void which varies with (1) the separation between the void and the electrode, (2) the ratio of the major to minor axes of the void and (3) the dielectric constant of the solid dielectric. The results show that the effect of the electrode on the field inside the void is negligible when the separation is greater than the major semi-axis of the void. The presence of the electrode near the void mitigates the electric field on the axis of symmetry of the void. However, higher field stress exists at the region away from the axis, and the field maximum is not significantly reduced by decreasing the separation, in particular for flatter voids. In order to present the potential induced by the void, higher order multipoles must be incorporated. The effect of the planar electrode on the equivalent multipole moments of the void is also discussed. © 1994-2012 IEEE.},

note = {cited By 0},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Techaumnat, B; Kadonaga, M

Electrostatic force behavior of a nonuniformly charged particle on a planar dielectric solid Journal Article

In: IEEE Transactions on Dielectrics and Electrical Insulation, vol. 18, no. 5, pp. 1366-1373, 2011, ISSN: 10709878, (cited By 7).

@article{Techaumnat2011,

title = {Electrostatic force behavior of a nonuniformly charged particle on a planar dielectric solid},

author = {B Techaumnat and M Kadonaga},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-80054076474&doi=10.1109%2fTDEI.2011.6032804&partnerID=40&md5=d4bd3a95812d0104a9579b33b8d21f9a},

doi = {10.1109/TDEI.2011.6032804},

issn = {10709878},

year = {2011},

date = {2011-01-01},

journal = {IEEE Transactions on Dielectrics and Electrical Insulation},

volume = {18},

number = {5},

pages = {1366-1373},

abstract = {This paper presents the analysis of the electrostatic force on a nonuniformly charged dielectric particle resting on a dielectric solid. The purpose of the analysis is to clarify the force enhancement caused by the nonuniform charging when the particle is on the dielectric solid, and to examine the role of the dielectric solid on the force behavior in the presence of an external electric field. The method of images using multipoles is applied to electric field calculation, and the electrostatic force is determined from the Maxwell stress. The analytical results show significant force enhancement due to nonuniform charging even in the case where the particle and the dielectric solid have the same dielectric-constant value. However, with an externally applied electric field, the nonuniform charging also results in higher force magnitude for detachment of the particle from the plane in comparison with the case of uniform charging. The roles of the dielectric constants of the media involved on the electrostatic force behavior are investigated. Critical difficulty for the detachment is not found for a particle with dielectric constant equal to 4, which is remarkably different from the corresponding case of a particle lying on a conducting plane. © 2006 IEEE.},

note = {cited By 7},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Kimura, Y; Gel, M; Techaumnat, B; Oana, H; Kotera, H; Washizu, M

Dielectrophoresis-assisted massively parallel cell pairing and fusion based on field constriction created by a micro-orifice array sheet Journal Article

In: Electrophoresis, vol. 32, no. 18, pp. 2496-2501, 2011, ISSN: 01730835, (cited By 28).

@article{Kimura2011,

title = {Dielectrophoresis-assisted massively parallel cell pairing and fusion based on field constriction created by a micro-orifice array sheet},

author = {Y Kimura and M Gel and B Techaumnat and H Oana and H Kotera and M Washizu},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-80052845718&doi=10.1002%2felps.201100129&partnerID=40&md5=8dda74fc6f3bb3af0c13d7bb541c8abc},

doi = {10.1002/elps.201100129},

issn = {01730835},

year = {2011},

date = {2011-01-01},

journal = {Electrophoresis},

volume = {32},

number = {18},

pages = {2496-2501},

abstract = {In this paper, we present a novel electrofusion device that enables massive parallelism, using an electrically insulating sheet having a two-dimensional micro-orifice array. The sheet is sandwiched by a pair of micro-chambers with immersed electrodes, and each chamber is filled with the suspensions of the two types of cells to be fused. Dielectrophoresis, assisted by sedimentation, is used to position the cells in the upper chamber down onto the orifices, then the device is flipped over to position the cells on the other side, so that cell pairs making contact in the orifice are formed. When a pulse voltage is applied to the electrodes, most voltage drop occurs around the orifice and impressed on the cell membrane in the orifice. This makes possible the application of size-independent voltage to fuse two cells in contact at all orifices exclusively in 1:1 manner. In the experiment, cytoplasm of one of the cells is stained with a fluorescence dye, and the transfer of the fluorescence to the other cell is used as the indication of fusion events. The two-dimensional orifice arrangement at the pitch of 50μm realizes simultaneous fusion of 6×103 cells on a 4mm diameter chip, and the fusion yield of 78-90% is achieved for various sizes and types of cells. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.},

note = {cited By 28},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Techaumnat, B; Washizu, M

Equivalent image charges of a prolate spheroid under an external electric field Journal Article

In: Journal of Electrostatics, vol. 69, no. 4, pp. 388-393, 2011, ISSN: 03043886, (cited By 9).

@article{Techaumnat2011a,

title = {Equivalent image charges of a prolate spheroid under an external electric field},

author = {B Techaumnat and M Washizu},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79959529381&doi=10.1016%2fj.elstat.2011.05.001&partnerID=40&md5=e689e63022ec7663a1ec2c5053b40ec0},

doi = {10.1016/j.elstat.2011.05.001},

issn = {03043886},

year = {2011},

date = {2011-01-01},

journal = {Journal of Electrostatics},

volume = {69},

number = {4},

pages = {388-393},

abstract = {This paper presents the image charges for a prolate spheroid under an external electric field. The equivalent image charges can substitute the spheroid to represent the potential that the free or polarization charges, induced by the external field on the spheroid, contribute to the exterior. In order to generalize the image charges for an arbitrary external field, we apply cylindrical image charges along the interfocal line of the spheroid, and explain the determination of the charge distribution and the calculation of the potential from the images. Examples are included to demonstrate the applicability of the image charges in field calculation. © 2011 Elsevier B.V.},

note = {cited By 9},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Takuma, T; Techaumnat, B

Electric Fields in Composite Dielectrics and their Applications Journal Article

In: Power Systems, vol. 56, 2010, ISSN: 16121287, (cited By 0).

@article{Takuma2010,

title = {Electric Fields in Composite Dielectrics and their Applications},

author = {T Takuma and B Techaumnat},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84882973226&doi=10.1007%2f978-90-481-9392-9&partnerID=40&md5=b07aed6bfde6375826d01a6d4129d219},

doi = {10.1007/978-90-481-9392-9},

issn = {16121287},

year = {2010},

date = {2010-01-01},

journal = {Power Systems},

volume = {56},

publisher = {Springer Verlag},

note = {cited By 0},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Gel, M; Suzuki, S; Kimura, Y; Kurosawa, O; Techaumnat, B; Oana, H; Washizu, M

Microorifice-based high-yield cell fusion on microfluidic chip: Electrofusion of selected pairs and fusant viability Journal Article

In: IEEE Transactions on Nanobioscience, vol. 8, no. 4, pp. 300-305, 2009, ISSN: 15361241, (cited By 37).

@article{Gel2009a,

title = {Microorifice-based high-yield cell fusion on microfluidic chip: Electrofusion of selected pairs and fusant viability},

author = {M Gel and S Suzuki and Y Kimura and O Kurosawa and B Techaumnat and H Oana and M Washizu},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-76949103725&doi=10.1109%2fTNB.2009.2035252&partnerID=40&md5=968e60ea98354bddadecc5cf7621c6de},

doi = {10.1109/TNB.2009.2035252},

issn = {15361241},

year = {2009},

date = {2009-01-01},

journal = {IEEE Transactions on Nanobioscience},

volume = {8},

number = {4},

pages = {300-305},

abstract = {Microorifice-based fusion makes use of electric field constriction to assure high-yield one-to-one fusion of selected cell pairs. The aim of this paper is to verify feasibility of high-yield cell fusion on a microfluidic chip. This paper also examines viability of the fusant created on the chip. We fabricated a microfluidic chip to fuse selected cell pairs and to study postfusion behavior. We used a self-forming meniscus-based fabrication process to create microorifice with a diameter of 210 $mu$m on the vertical walls in a microfluidic channel. When 1 MHz was applied to electrodes located on both sides of the microorifice, dielectrophoretic force attracted the cells toward microorifice to form a cell pair. Once the cells get into contact, fusion pulse was applied. Real time imaging of cells during fusion and cytoplasmic dye transfer between cells indicated success of cell fusion. We found that when high frequency voltage for dielectrophoresis was swept from 1 MHz to 10 kHz in 100 $mu$s, cell fusion was initiated. The effective electric field strength was 0.10.2 kV/cm. We analyzed viability by imaging fusant going into cell division phase after 48 h of incubation. We conclude that fabricated microfluidic chip is suitable for high-yield one-to-one fusion and creation of viable fusants. This technology should be a useful tool to study fusion phenomena and viability of fusants, as it allows imaging of the cells during and after the fusion. © 2006 IEEE.},

note = {cited By 37},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Techaumnat, B; Takuma, T

Analysis of the electrostatic force on a dielectric particle with partial charge distribution Journal Article

In: Journal of Electrostatics, vol. 67, no. 4, pp. 686-690, 2009, ISSN: 03043886, (cited By 13).

@article{Techaumnat2009,

title = {Analysis of the electrostatic force on a dielectric particle with partial charge distribution},

author = {B Techaumnat and T Takuma},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67349268158&doi=10.1016%2fj.elstat.2009.03.004&partnerID=40&md5=373f2b716f035017254ba7f308881d23},

doi = {10.1016/j.elstat.2009.03.004},

issn = {03043886},

year = {2009},

date = {2009-01-01},

journal = {Journal of Electrostatics},

volume = {67},

number = {4},

pages = {686-690},

abstract = {This paper presents the analysis of the electrostatic force acting on a charged dielectric particle on a grounded plane. The force has been determined by a numerical field calculation method to make clear the effect of particle dielectric constant and charge distribution on the particle surface. The charge is treated to be distributed in three ways: (a) uniformly over entire surface, (b) partially on the upper, or (c) on the lower part of a particle. The calculation results show that, if a particle with dielectric constant εp = 3 is partially charged on the lower part by a zenith angle π/2, π/4 and π/8, the force shall be higher by 0.7, 4.3 and 20 times, respectively, than that for a uniform charging with the same charge amount. On the other hand, the force becomes weaker when charge is on the upper part. The effect of the particle dielectric constant is found to be dependent on the charge distribution. With charge uniform on the entire surface or on the upper part, the force always increases with the dielectric constant. However, when surface charge is restricted to a small area at the lower part of the particle (θq < π/4), the force may decrease with increasing the dielectric constant. © 2009 Elsevier B.V. All rights reserved.},

note = {cited By 13},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Techaumnat, B; Kadonaga, M; Takuma, T

Analysis of electrostatic adhesion and detachment of a nonuniformly charged particle on a conducting plane Journal Article

In: IEEE Transactions on Dielectrics and Electrical Insulation, vol. 16, no. 3, pp. 704-710, 2009, ISSN: 10709878, (cited By 8).

@article{Techaumnat2009a,

title = {Analysis of electrostatic adhesion and detachment of a nonuniformly charged particle on a conducting plane},

author = {B Techaumnat and M Kadonaga and T Takuma},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67651151479&doi=10.1109%2fTDEI.2009.5128509&partnerID=40&md5=1dd67317aae410b834e667d7d8e36220},

doi = {10.1109/TDEI.2009.5128509},

issn = {10709878},

year = {2009},

date = {2009-01-01},

journal = {IEEE Transactions on Dielectrics and Electrical Insulation},

volume = {16},

number = {3},

pages = {704-710},

abstract = {This paper presents the analysis of electrostatic adhesion and detachment of a charged, dielectric particle resting on a conducting plane. We have studied the effects of particle dielectric constant and the nonuniform charge distribution on the force acting on the particle. Charge on the particle surface is assumed to be smoothly varied and (a) concentrated at the bottom pole or (b) concentrated at the top and bottom poles. The analysis utilizes the method of multipole images to obtain accurate values of the electric field, and determines the electrostatic force from the stress on particle surface. Compared with the force on a uniformly charged particle having the same total charge amount, the analytical results show that the force is significantly enhanced by both kinds of nonuniform charge distribution treated in this work, and is particularly strong when charge is highly concentrated at the bottom pole. It is found that electric field in a limited range must be applied in order to detach the particle from the conducting plane. The electric field necessary for detachment depends strongly on the dielectric constant and the distribution of charge on the particle. The detachment becomes difficult for a particle with charged distributed at the bottom pole, and may be hardly possible if the dielectric constant is too high. © 2006 IEEE.},

note = {cited By 8},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Techaumnat, B; Tsuda, K; Kurosawa, O; Murat, G; Oana, H; Washizu, M

High-yield electrofusion of biological cells based on field tailoring by microfabricated structures Journal Article

In: IET Nanobiotechnology, vol. 2, no. 4, pp. 93-99, 2008, ISSN: 17518741, (cited By 22).

@article{Techaumnat2008,

title = {High-yield electrofusion of biological cells based on field tailoring by microfabricated structures},

author = {B Techaumnat and K Tsuda and O Kurosawa and G Murat and H Oana and M Washizu},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-56749159879&doi=10.1049%2fiet-nbt%3a20080008&partnerID=40&md5=2d3cd6f69f71561a3916d666b246f098},

doi = {10.1049/iet-nbt:20080008},

issn = {17518741},

year = {2008},

date = {2008-01-01},

journal = {IET Nanobiotechnology},

volume = {2},

number = {4},

pages = {93-99},

abstract = {The authors present the use of electric-field constriction created by a microfabricated structure to realise high-yield electrofusion of biological cells. The method uses an orifice on an electrically insulating wall (orifice plate) whose diameter is as small as that of the cells. Owing to the field constriction created by the orifice, we can induce the controlled magnitude of membrane voltage selectively around the contact point, regardless of the cell size. The field constriction also ensures 1:1 fusion even when more than two cells are forming a chain at the orifice. A device for electrofusion has been made with a standard SU-8 lithography and PDMS molding, and real-time observation of the electrofusion process is made. Experiments using plant protoplasts or mammalian cells show that the process is highly reproducible, and the yield higher than 90 is achieved. © 2008 The Institution of Engineering and Technology.},

note = {cited By 22},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Washizu, M; Techaumnat, B

Polarisation and membrane voltage of ellipsoidal particle with a constant membrane thickness: A series expansion approach Journal Article

In: IET Nanobiotechnology, vol. 2, no. 3, pp. 62-71, 2008, ISSN: 17518741, (cited By 7).

@article{Washizu2008,

title = {Polarisation and membrane voltage of ellipsoidal particle with a constant membrane thickness: A series expansion approach},

author = {M Washizu and B Techaumnat},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-49149120096&doi=10.1049%2fiet-nbt%3a20080003&partnerID=40&md5=1753808efc847e88d1ecbde298d7446f},

doi = {10.1049/iet-nbt:20080003},

issn = {17518741},

year = {2008},

date = {2008-01-01},

journal = {IET Nanobiotechnology},

volume = {2},

number = {3},

pages = {62-71},

abstract = {The estimation of the membrane voltage and the polarisation factor of biological cells provide a base for the study of bio-manipulation techniques, such as dielectrophoresis, electroporation or electrofusion. To model a biological cell, an ellipsoidal particle with an insulating membrane is sometimes employed, but due to the limitation of the confocal nature of the coordinate system, the membrane thickness is assumed to vary with the position, despite the fact that the lipid bilayer membrane has a uniform thickness. The authors present a method to rigorously treat the uniform-thickness condition in a system having an axial symmetry. The method is based on the harmonic expansion of the field, to include the condition of the uniform-membrane thickness as a series expansion of the geometrical factor, and to solve the field problem as an interaction of the harmonic components. The conventional variable thickness model has been identified as being equivalent to neglecting the harmonic interactions in the uniform-thickness model. Numerical calculations are done of the membrane voltage and the polarisation factor, and it has been found that the discrepancy between the proposed rigorous model and the conventional variable thickness model becomes significant when field deformation is large due to the high axial ratio of the ellipsoid. © 2008 The Institution of Engineering and Technology.},

note = {cited By 7},

keywords = {},

pubstate = {published},

tppubtype = {article}

}