A Study On Key Technologies In Bioelectromagnetics Using Computational Electromagnetics And Parallel Computing

Bioelectromagnetics (BEM) is the study of electromagnetic phenomena within and between biological systems. With the development of technologies, the electromagnetic environment becomes more and more complicated, therefore the biological effects caused by electromagnetic radiation and human body-centric wireless network have proved to be the key technologies in BEM. Because life body is very complicated, we should use more research methods to deal with one problem. Computer simulation is the commonly used method, because using this method we can simulate the nature life. Nowadays, the computational biology methods have been becoming the key technology of life science and engineering of biology and medicine. Supported by the national natureal science fundation of China and the innovation fundaiton of Beijing University of Posts and Telecommunications, this paper studies the applications of computational electromagnetics and parallel computing in BEM simulation modeling, especially the parallel impedance method and finite-difference time-domain method for BEM simualtion. These research works include the simulation of the induced current distribution in human body exposed to the electromagnetic fields of power transmition line and transcranial magnetic stimulation, the specific absorbed rate distribution in human body when wearing a Bluetooth RF device, the modeling of the computer video display unit, the biology effect of human brain when working in front of the computer monitor, proposed the concept of wearable network and estimating channel character for narrowband wearable network construced by Bluetooth, and giving the design of the planar inverted-F antenna and coupled planar dipole UWB antenna for narrow and broad band wearable network respectively. The main novel works included in this dissertation are as follows:1 The implemention of the parallelized three-dimensional impedance method is proposed and verified. Based on Maxwell's equation, the three-dimensional impedance method is deduced and the association numerical model has been found between the minimum incident wave length and the resolution of human body model. Furthermore, a communication scheme to exchange the border data for processors during iteration by message passing interface (MPI) library is designed and a parallel computer system has been set up. The validation and effective of parallel IM is verified by simulation experiment.2 In BEM application, the FDTD method is rededuced into splited formations and scattered fields in lossy medium. Forthermore, the constitutive medium is modified to improve the numerical dispersion. The non-uniform mesh technology is discussed.3 Set up a numerical model for calculating the induced current in humen body when exposed in electromagnetic fields. The simulations of the induced current in human body is made, when exposed to 100μT (1000mG), which is the limit recommended by the ICNIRP for the public and to 0.4μT (4mG), which is the level at which there appears to be a statistical link with a doubled risk of development of childhood leukaemia based on paralled impedance method. The induced current in human body exposure to power line for lineman and dweller and the induced current density distribution in human head model caused by transcranial magnetic stimulation (TMS) are also simulated for clinical application.4 The SAR distribution in a High-Fidelity human body model caused by 2.4GHz band planar inverted-F antenna (PIFA) for Bluetooth application and the PIFA performance affected by human body have been studied by the sub-grid finite-difference time-domain (FDTD) method. The results can provied safety guarantee for body-centric wireless network and wearable network.5 In order to consider the video imformation security, based on the radiation of moving charges, a model is proposed for the electromagnetic field of electron beam in acceleration region of CRT. From this model, the radiation field is directly associated with electron beam's current, and it can be analyzed and calculated by numerical method. Further, the frequency spectrum of radiation field has been transformed. The character of frequency spectrum is that each lobe has the same video information. The whole spectrum and the video signals can be recovered by processing each lobe. The numerical simulation results are in agreement with experiments.The human head effect is simulated by FDTD.6 With the development of mobilephone, Bluetooth earphone, wireless network card, wireless router and wearable- computers are frequently used near the human body. Quite soon we will see a wide range of unobtrusive wearable and ubiquitous computing equipment integrated into our everyday wear and the body-centric wireless network equipment will be studied bloomingly. Considering the applications, we propose the concept of the wearable network. The planar inverted-F antenna is simulated and designed for Bluetooth wearable network and the on-body channel character is estamated and measured. The effects of deep breath, metal ornament and body movement are studied. The couple planar dipole UWB antenna is also designed for ulta-wide band wearable network.