Conference Agenda

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Session Overview
PB-A1: Bio-Electromagnetic Computation
Wednesday, 17/Jul/2019:
2:20pm - 4:10pm

Session Chair: Markus Clemens
Session Chair: Maurizio Repetto
Location: Patio 44-55

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Taguchi Method and Finite Element Method for Electromagnetic Thermotherapy Optimal Soft Coil Design

Cheng-Chi Tai, Chia-Jung Chang, Jian-Jhih Hong

National Cheng Kung University, Taiwan

Electromagnetic thermotherapy is currently a cancer treatment with fewer side effects. By passing high-frequency currents through an induction coil to generate an alternating magnetic field, a magnetic metal needle is rapidly heated by the induced eddy currents to kill tumor cells. When the metal needle is perpendicular to the coil plane, the needle temperature is closely related to the magnetic field strength. Nevertheless, the metal needle not perpendicular to coil plane would not effectively induce the magnetic field to generate Joule heat that the needle temperature would obviously reduce. Taguchi Method is combined with Finite Element Method (FEM) in this study to decide the high needle temperature response coil (High T Coil). Adaptive Neuro-Fuzzy Inference System(ANFIS) model is used with Genetic Algorithm (GA) to find out the low needle temperature variation coil (Low T Coil), under changing needle insertion angles, for the application to the electromagnetic thermotherapy system. An optimization design procedure is proposed in this study to enhance the metal needle temperature. Besides, a coil design process is proposed to release the decreasing metal needle temperature, under changing needle insertion angles. Finally, the coil is actual winded to test the metal needle heating effect under High T Coil at different coil depths of 1, 3, and 5 cm. Besides, the heating results of the metal temperature variation using Low T Coil at the 45 degree is analyzed and discussed.

A GPU-Accelerated Solver for Scattering Problems in Voxel-Based Anatomical Human Models

Alessandro Arduino, Oriano Bottauscio, Luca Zilberti

Istituto Nazionale di Ricerca Metrologica, Italy

In this paper, a GPU-accelerated implementation of a three-dimensional full-wave electromagnetic solver for scattering problems is compared, in terms of performances, with a serial CPU implementation of the same method. The achieved speed-up with respect to the serial code is about 13 for medium-size problems. Finally, as an example of application, the described code is used to compute the specific absorption rate of a magnetic resonance imaging radiofrequency birdcage coil in a voxel-based anatomical head model.

Magnetically Mediated Thermoacoustic Imaging of Magnetic Nanoparticles under Short Pulsed Magnetic Field

Yanhong Li1,2, Guoqiang Liu1,2, Jiaxiang Song1,2, Hui Xia1, Shiqiang Li1, Chao Zhang1

1Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, CO 100190 China; 2University of Chinese Academy of Sciences, Beijing, CO 100049 China

Magnetically Mediated Thermoacoustic Imaging(MM-TAI) with short pulsed magnetic field of magnetic nanoparticles(MNPs) is reported here. In order to study the influence of adding magnetic nanoparticles as a contrast agent for MM-TAI on its physical process, the electromagnetic field and acoustic field physical model are built, and the heat absorption distribution with the resistance loss and the magnetic loss as thermoacoustic source is proposed. The numerical simulation method to solve the problem of micro-scare for magnetic nanoparticles is proposed. The finite element simulation and the experiment are performed to verify the validity of the theory. Pulsed excitation is considered in the analysis, which is different from previously reported research. These proof-of-concept experiments showcase the potential to integrate thermoacoustic imaging with nanoparticle hyperthermia system.

Numerical Aspects in Dosimetric Analysis of Human Exposure to Wireless Power Transfer for Electric Vehicles

Alessandro Arduino1, Oriano Bottauscio1, Mario Chiampi1, Luca Giaccone3, Ilaria Liorni2, Niels Kuster2, Luca Zilberti1, Mauro Zucca1

1Istituto Nazionale di Ricerca Metrologica, Italy; 2IT’IS Foundation, Zurich, Switzerland; 3Politecnico di Torino, Torino, Italy

In this work, numerical aspects related to the accuracy of numerical dosimetric simulations, performed in the context of human exposure to wireless power transfer systems for electric vehicles, are discussed. Two alternative methods for electric field computation in highly detailed anatomical human models are applied, discussing results in the framework of the current regulations and guidelines. Different strategies for smoothing localized outliers are compared, including novel techniques based on statistical considerations.

A computational procedure for predicting the thermal effects produced by MRI gradient coils in orthopedic implants

Alessandro Arduino1, Oriano Bottauscio1, Rüdiger Brühl2, Mario Chiampi1, Luca Zilberti1

1Istituto Nazionale di Ricerca Metrologica, Italy; 2Physikalisch-Technische Bundesanstalt, Germany

This work proposes a numerical procedure for accurately evaluating the energy deposed by MRI gradient coils in bulk metallic prostheses and the consequent temperature increase of the surrounding tissues. An original method, based on a time periodic approach, allows to accurately reproduce the evolution of the phenomena produced by the switching gradient field associated with any MRI sequence. Then, the Pennes’ bioheat equation is solved through the Douglas–Gunn method to compute the time-dependent temperature increase, which can be superposed to the thermal effects caused by the RF fields. As an example, the procedure is applied to evaluate the heating generated inside the body when a patient with a hip prosthesis undergoes a Echo-Planar Imaging (EPI) MRI sequence.

The Study on Safety Distance between Human Body and Electric Vehicle Wireless Charging System with Different Frequencies

Nailiang Li1,2, Jun Zhao1,2, Lei Wang1,2, Ting Yang1,2, Zhijun Wu1,2, Xinsheng Yang1,2, Wenjia Yang3

1State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, China, People's Republic of; 2Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Hebei University of Technology, China, People's Republic of; 3The Hong Kong Polytechnic University, Department of Electrical Engineering, Hong Kong

In this paper, the field-circuit coupling method is applied to the finite element analysis of the wireless energy transmission system. The overall trend of transmission efficiency and the system frequency are simulated so that the operating frequency range of the electric vehicle wireless charging system is determined. The electromagnetic field parameters of the human body during the wireless charging process of the electric vehicle are calculated, and the safety distance between the human body and the wireless energy transmission system at different frequencies is defined. On this basis, the electromagnetic thermal effects of the human body implanted with a pacemaker were analyzed by means of multi-physics coupling.

In Silico Electrical Modeling of Cell Aggregates

Pouria Mistani1, Floriane Gidel3, Damien Voyer2,3, Frederic Gibou1,4, Clair Poignard3

1Department of Mechanical Engineering, University of California, Santa Barbara; 2EIGSI La Rochelle; 3Team MONC, INRIA, CNRS UMR 5251, Bordeaux INP; 4Department of Computer Science, University of California, Santa Barbara, CA 93106-5110, USA

Multicellular spheroids are interesting 3D in vitro models that mimic the tissue organization. In the context of electroporation, the interest of 3D spheroids has greatly increased. We present here a numerical method that enables to characterize the electroporation of 3D spheroids, and to exhibit micro and macroscopic electrical behaviors of such cell aggregates. Our parallel Voronoi Interface Method allows us to compute nonlinear electroporation model in a spheroid composed of more than 30 000 cells. In the forthcoming study our computational strategy will provide a powerful tool to characterize the spheroid sample, proposing thus a novel computational method of electrical characterization of cell aggregates.

Simulation Analysis of Transcranial Magneto-Acoustical Electrical Stimulation Based on Realistic Human Head Model

Shuai Zhang1,2, Yaze Liu1,2, Zhenyu Zhou1,2, Kun Cui1,2, Guizhi Xu1,2

1State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin, China; 2Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Hebei University of Technology, Tianjin, China

Transcranial magneto-acoustical electrical stimulation (TMAES) is a novel neuromodulation method that uses ultrasound and static magnetic fields to act on nerve tissue to regulate neuronal discharge activity. Multilayer structure and geometry of the human head play an important role in the distribution of the acoustic field and the induced electric field by TMAES. Therefore, in this study we applied the human head CT image to extract the three parts of the scalp, skull and brain, and then obtained the realistic human head model by three-dimensional reconstruction. Then we used finite element analysis (FEA) to simulate TMAES based on realistic human head model. The simulation results showed that there is a high consistency between the acoustic field and the induced current density. The results also indicated that TMAES is suitable for precise stimulation and deep stimulation. This paper reveals the focus distribution characteristics of TMAES and may help to provide theoretical basis for improving the accuracy of TMAES.

Modeling of exposure to low frequency electromagnetic fields of workers in arbitrary posture

Alice Conchin Gubernati1, Fabio Freschi1, Luca Giaccone1, Riccardo Scorretti2, Laurent Seppecher3, Grégory Vial3

1Politecnico di Torino, Italy; 2Lab. Ampère, CNRS UMR 5005, École Centrale de Lyon, France; 3Université de Lyon, CNRS UMR 5208, École Centrale de Lyon, France

At present time, numerical dosimetry has reached a certain maturity and dedicated commercial software exist. However, fast and accurate characterization of exposure in real condition is still challenging, among other reasons, because the exact posture of the “victim” has to be taken into account. The classical approach is to estimate the source magnetic field and then to perform a dosimetric computation with a postured phantom. We propose a different approach, based on a change of variable, which takes the postured phantom to a not postured one. We demonstrate that this procedure ends up in a change of tissue conductivity, which is localized in knees, elders and other articulations, where deformations due to posturing are large.

Numerical modeling of floating potentials in electrokinetic problems

Damien Voyer1,2, Sergio Corridore2, Annabelle Collin2, Riccardo Scorretti3, Clair Poignard2

1EIGSI La Rochelle, France; 2Team MONC, INRIA, CNRS UMR 5251, Bordeaux INP, Talence, France; 3Université de Lyon, Ampère, UMR 5005, Ecully, France

Floating potentials appear in electrokinetic problems when isolated domains with high conductivity are introduced. An asymptotic development is proposed in order to avoid the direct computation that leads to inaccurate numerical results when the contrast of conductivity is strong. We show that the problem where perfect conductors are assumed is the zero order solution of the initial problem; the solution can then be refined introducing a first order correction that implies two successive problems defined inside and outside the domains with high conductivity. The proposed example deals with a four electrodes system designed to both induce electroporation in a biological tissue sample and measure the resulting impedance. The proposed approach is extended to a nonlinear problem by taking advantage of the iterative solution that is necessary applied in this case.

Research on Intervention Effect of Magnetic Nanoparticles in Magnetic Field on Lung Tumor

Naming Zhang1,3, Shuya Ning2, Shuhong Wang1, Song Wang1

1State Key Laboratory of Electrical Insulation and Power Equipment, Faculty of Electrical Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China; 2College of Electrical and Information Engineering, Shaanxi University of Science and Technology, Xi’an, Shaanxi, 710021, China; 3Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD, 21225, USA

The mutations in K-Ras result in normal cells dividing uncontrollably and turning cancerous, and patients with poor prognosis due to the lack of drugs that can effectively target mutant K-Ras. In the present study, the magnetic nanoparticles based on Ferro ferric oxide were synergized with the magnetic field to intervene the proliferation and migration of lung tumor A549 cell line (K-Ras driven). The tumor cells were checked by the electron microscope. The proliferation of tumor cell was examined. The level of cell migration was checked by wound healing assay. Based on the previous study, the cell experiments showed that the MNPs synergized with the magnetic field not only suppress the tumor cell proliferation but also cell migration.

Analysis of Reconstructed Image Characteristics of Conducting Spherical Objects using Time Domain Scattered Signal Sinograms

M. Alper Selver1, Mustafa Secmen2, E. Yesim Zoral1

1Dokuz Eylul University, Turkey; 2Yasar University

Terahertz Computed Tomography (THz CT) is an emerging modality for various important imaging applications. The quality of reconstructed images from scattered THz rays are under the influence of several parameters, which have not been analyzed in detail. Conducting spheres constitute important objects for THz CT imaging applications as their scattering behavior can be modeled exactly with numerical analysis. Thus in this study, scattered signals from conducting spherical objects having different diameters and internal structures (empty and filled) are generated by rotating the observation point around the object. The resulting set of scattered signals are first used to create a time-domain sonogram. Then, the image of the object is generated using filtered back-projection technique. The quality differences of the reconstructed images are measured and analyzed by using several metrics such as mean square error, signal to noise ratio and structural similarity index. The results parametrically reveal important factors effecting the image quality for THz-CT.

Study on Transcutaneous Energy Transmission Device Optimal Design

Guilherme Antonio Rodrigues, Luiz Lebensztajn

Escola Politécnica da Universidade de São Paulo, Brazil

Wireless Energy Transmission Devices have been used in industry applications for a long time. Nowadays, this technology is being adapted to other types of applications and areas, such as electric powered cars and transcutaneous energy transmission (TET) devices. This work presents an approach that purposes to introduce some tools, such as finite elements modeling and optimization methods, in order to obtain a system that is able to transmit the prescribed energy for TET. Furthermore, the objective is to observe if the optimal device’s temperature during its operation exceeds the limits that an individual can withstand.

Numerical Simulation of Conductivity Reconstruction for Magneto-acousto-electrical Tomography

Yuan yuan Li1,2, Guoqiang Liu1,2, Jiaxiang Song1,2, Hui Xia1, Chao Zhang1

1Institute of Electrical Engineering, Chinese Academy of Sciences, China, People's Republic of; 2University of Chinese Academy of Sciences,School of Electronic Electrical and Communication Engineering, Beijing, China, People's Republic of

Magneto-acousto-electrical Tomography (MAET) is a hybrid imaging modality, which combines the merits of high contrast and high resolution for imaging, and extremely useful for electrical conductivity measurement. In this paper, a numerical framework were proposed to simulate the MAET measurements by two electrodes. And a new image reconstruction scheme for which data on electrodes were built. Firstly, the time-reverse were introduced to recover the divergence of the cross product of current density in the reciprocal process and static magnetic field. Secondly, the distribution of electrical conductivity were recovered by the iterative algorithm. The new methods were introduced to recover the distribution of conductivity in Magneto-acousto-electrical Tomography of 3D model. The reconstructed images of conductivity were consistent with the original distribution, which validated the new method.

New formulations for numerical dosimetry of electromagnetic field at intermediate frequencies

Giacomo di Benedetto1, Riccardo Scorretti1, Christophe Geuzaine2, Kassem Jomaa3, Melina Bouldi4, Fabien Ndagijimana3

1Université de Lyon, Ecole Centrale de Lyon, CNRS, Ampère, F-69130, Ecully, France; 2University of Liège, Department of Electrical Engineering and Computer Science, Grande Traverse 10, 4000 Liege, Belgium; 3IMEP-LaHC Laboratory, Grenoble, France; 4INRS Nancy, France

Numerical dosimetry of electromagnetic field induced in the human body by electrical devices at intermediate frequencies usually requires an accurate characterization of the radiating source.

Normally, exposure is characterized in terms of the electric component of the field.

However, at those frequencies it is much easier to measure the magnetic field.

In this work we present new formulations for numerical dosimetry which uses the magnetic field as unique source term.

Study on the Human Body Transient Electric Shock under HVDC Transmission Line

Jian Wu1,2, Shuhong Wang1, Bin Yang2, Wen Han2, Rui Li3, Guangzhou Zhang4

1Xi'an Jiaotong University, China, People's Republic of; 2State Grid Shaanxi Electric Power Research Institute; 3State Grid Corporation of China; 4NARI Group Corporation

Human body transient electric shock under HVDC transmission line is a phenomenon that causes a serious risk to life safety. In this paper, the phenomenon is studied based on the measurement and the simulation. Firstly, the model of human body transient electric shock in 800kV DC ion flow field is established, and then the induced voltage on the metal plate is calculated according to ionic current density. Secondly, calculating the charging voltage when the human body is shocked based on a circuit model of human body and metal plate. Thirdly, the model of HVDC transmission line is built in the laboratory, and the human body transient electric shock is simulated under the transmission line to verify the correctness of the simulation. Finally, based on the level of influence of transient electric shock on people, the limit of corona field intensity of HVDC conductor is proposed.

Simulation and Analysis of Local Field Potentials Based on Neocor-tical Neurons with Transcranial Ultrasonic Magnetic Stimulation

Shuai Zhang1,2, Xinyu Gao1,2, Liang Guo1,2, Mingkang Zhao1,2, Guizhi Xu1,2

1State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin, China; 2Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Hebei University of Technology, Tianjin, China

Transcranial magnetic-acoustical electrical stimulation (TMAES) of nerve or cortical tissue is a relatively new tool for non-invasive modulation of the brain and nervous system. The technology utilizes the magneto-acoustic electrical effect generated by the interaction of the static magnetic field and the ultrasonic wave to generate an induced current in the nerve tissue, thereby stimulating the nerve tissue. Compared with Transcranial Direct Current Stimulation (tDCS) and transcranial magnetic stimulation (TMS), transcranial ultrasound magnetic stimulation has higher spatial resolution and deeper penetration. The local field potential (LFP) reflects the local activity of many neurons near the recording electrode and can be used to study local network dynamics. Based on the neocortical neuron model, the local field potential changes were studied by comparing single neurons and neuron clusters without stimulation and TMAES. Simulation experiments show that the parameter values of TMAES affect the stimulation intensity, resulting in different degrees of stimulation behavior. The neuron itself handles different input information differently. It can be seen that the magneto-acoustic effect of TMAES leads to a change in different extracellular potentials. These findings help to find better ways to control nerves.

Multiphysics modeling of electromagnetically controlled shape memory polymer medical stents

Innocent Niyonzima1,2, Olivier Chadebec1, Gérard Meunier1, Nicolas Galopin1, Jacob Fish2

1Univ. Grenoble Alpes, CNRS, Grenoble INP, G2ELab, F-38000 Grenoble, France; 2Columbia University, Department of Civil Engineering and Engineering Mechanics, New York, 10027 NY, USA.

This paper deals with the multiphysics modelling of thermal-responsive shape memory polymer biomaterials. These materials can change their mechanical properties with the changing temperature. Thermal contactless control can be achieved by the adding electric or magnetic particles that can react to electromagnetic fields by generating heat. These materials can be used to design medical stents. During its deployment, the stent undergoes large mechanical deformations which make its modelling more involved. In this paper we present large deformations formulations of the multiphysics problem and use them to model the deployment of a shape memory polymer medical stent.