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FDTD calculations of specific absorption rate in fetus caused by electromagnetic waves from mobile radio terminal using pregnant woman model

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IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES 2008年第2期56卷 554-559页

作者： Togashi, Toshihiro Nagaoka, Tomoaki Kikuchi, Satoru Saito, Kazuyuki Watanabe, Soichi Takahashi, Masaharu Ito, Koichi Chiba Univ Res Ctr Frontier MEd Engn Chiba 2638522 Japan

Since the diversification of the electromagnetic (EM) environment is spreading, it is essential to estimate the EM energy absorption rate [specific absorption rate (SAR)] of a pregnant woman's body and her fetus under various exposure situations. This paper presents the EM dosimetry in a pregnant woman in proximity to a mobile-phone terminal using the numerical model of a woman in her seventh month of pregnancy (composed of 56 organs, which includes the intrinsic organs of a pregnant woman) based on the high-resolution whole-body voxel model of a Japanese adult woman. It was found that. the SAR in the fetus strongly depends on the geometrical relationship between the fetus and the EM source, while the averaged SAR for the fetus is always lower than the RF safety guidelines under the exposure conditions investigated in this paper.

关键词： fetus finite-difference time-domain method magnetic resonance imaging mobile radio terminal pregnant woman specific absorption rate (SAR)

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FDTD simulation on the interaction between gaussian beam and biaxial anisotropic metamaterial slabs

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INTERNATIONAL JOURNAL OF INFRARED AND MILLIMETER WAVES 2008年第2期29卷 167-178页

作者： Wang, Maoyan Wu, Jian Xu, Jun Ge, Debiao Li, Hailong Feng, Jian Univ Elect Sci & Technol China Sch Phys Elect Chengdu 610054 Sichuan Peoples R China China Res Inst Radiowave Propagat Natl Key Lab Electromagnet Environm Beijing 102206 Peoples R China Xidian Univ Sch Sci Xian 710071 Shanxi Peoples R China China Res Inst Radiowave Propagat Qingdao 266107 Shandong Peoples R China

The interaction between Gaussian beam and indefinite anisotropic metamaterial (AMM) slabs are simulated with auxiliary differential equation method in finite-difference time-domain method (FDTD). The directions of wave vector and energy flow densities in three types of AMM slabs are investigated. The field intensity distributions and phases of TE-polarized wave for the interaction between Gaussian beam and AMM slabs are given. Numerical results show that the sign of x component of relative permeability tensor of AMM determines the refraction is regular or anomalous, whereas the sign of z component of relative permeability tensor of AMM determines the energy flow is positively refracted or negatively refracted. Positive or negative Goos-Hanchen shift associated with Total Cutoff media are also shown.

关键词： anisotropic metamaterials finite-difference time-domain method auxiliary differential equation method negative refraction

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Splitting finite difference methods on Staggered Grids for the Three-Dimensional time-Dependent Maxwell Equations

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Communications in Computational Physics 2008年第7期4卷 405-432页

作者： Liping Gao Bo Zhang Dong Liang School of Mathematical Sciences Shandong Normal UniversityJinan 250014China. Institute of Applied Mathematics Chinese Academy of SciencesBeijing 100080China. Department of Mathematics and Statistics York University4700 Keele StreetTorontoOntario M3J 1P3Canada

In this paper,we study splitting numerical methods for the three-dimensional Maxwell equations in the time *** propose a new kind of splitting finitedifference time-domain schemes on a staggered grid,which consists of only two stages for each time *** is proved by the energy method that the splitting scheme is unconditionally stable and convergent for problems with perfectly conducting boundary *** numerical dispersion analysis and numerical experiments are also presented to illustrate the efficiency of the proposed schemes.

关键词： Splitting scheme alternating direction implicit method finite-difference time-domain method stability convergence Maxwell’s equations perfectly conducting boundary

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Applicability of Temperature Distribution for Estimation of Medium Constants Using Temperature Rise due to Absorption of Ultrasound

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JAPANESE JOURNAL OF APPLIED PHYSICS 2008年第5期47卷 4145-4148页

作者： Yamaya, Chiaki Inoue, Hiroshi Akita Univ Fac Engn & Resource Sci Dept Elect & Elect Engn Akita 0108502 Japan

The analysis of temperature rise due to the absorption of ultrasound is important for the clarification of the effect of ultrasound waves and the estimation of medium constants. The thermal behavior of ultrasound is used not only for thermotherapy but also in measurement techniques. The estimation of a medium constant becomes possible by analyzing the temperature rise because the temperature change of the medium is particular to each medium. The purpose of this research is to establish a method of estimating medium constants and to develop a numerical simulation method that can be applied to the estimation of medium Constants. We elucidated the requirements under which the simulation result corresponds to the experimental result. Good agreement between the experimental and simulation results is shown in this paper, and the validity of this method is described. [DOI: 10.1143/JJAP.47.4145]

关键词： thermal behavior of ultrasound absorption of ultrasound finite-difference time-domain method heat analysis

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Numerical study of near-infrared photodetectors with surface-plasmon antenna for optical communication

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JAPANESE JOURNAL OF APPLIED PHYSICS 2008年第4期47卷 2921-2923页

作者： Okamoto, Daisuke Fuilkata, Junichi Nishi, Kenichi Ohashi, Keishi NEC Corp Ltd Nano Elect Res Labs Tsukuba Ibaraki 3058501 Japan

We propose an InP-based nanoscale metal - semiconductor - metal photodiode with a surface plasmon antenna composed of gold slit arrays for optical communication systems. Resonant modes of the surface plasmon antenna are numerically simulated by the finite-difference time-domain method, The calculation results suggest the advantage of the hybrid mode, which is produced by a Wood - Rayleigh anomaly mode and a vertical cavity mode. The hybrid mode enables a quantum efficiency of more than 50% when using a 250-nm-thick InGaAs absorption layer. A higher efficiency of about 95% can be achieved by combining a surface plasmon antenna with a distributed Bragg reflector consisting of 20 periods of quarter-wave InP/InGaAsP layers.

关键词： surface plasmon metal - semiconductor - metal photodiode subwavelength grating compound semiconductor optical communication distributed Bragg reflector finite-difference time-domain method

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Numerical solution of Maxwell's equations for anisotropic media using the Laguerre transform

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RUSSIAN GEOLOGY AND GEOPHYSICS 2008年第8期49卷 621-627页

作者： Mastryukov, A. F. Mikhailenko, B. G. RAS Siberian Branch Inst Comp Math & Math Geophys Novosibirsk 630090 Russia

We apply the spectral Laguerre transform in the time domain to solve 2D Maxwell's equations for propagation of electromagnetic waves in lossy anisotropic media. The new algorithm is simple and efficient as Maxwell's equations are reduced to a harmonic series of linear algebraic equations where the matrix is independent of the harmonic order and is the same for all harmonics. The efficiency of the algorithm is improved by fitting a specially introduced free parameter of the Laguerre transform. If it is large, the solution spectrum shifts toward higher harmonics which is formally equivalent to the case of ray approximation. The Laguerre solution is comparable with high-order accurate finite-difference time-domain (FDTD) solutions. The method is stable both in the region of the wavefield, where conductivity approaches zero and the spectral Fourier method is unstable, and in the high-conductivity region, where the explicit FDTD code requires a too small time step. (C) 2008, IGM, Siberian Branch of the RAS. Published by Elsevier B. V. All rights reserved.

关键词： Maxwell's equations electromagnetic waves anisotropic media relaxation time conductivity dielectric permittivity Laguerre transform finite-difference time-domain method linear equation system

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Study of superluminal-pulse propagation in one-dimensional photonic crystals by the FDTD method

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JOURNAL OF RUSSIAN LASER RESEARCH 2008年第2期29卷 176-183页

作者： Chen, Yu-lin Fang, Yun-tuan Nanjing Univ Informat Sci & Technol Coll Math Nanjing 210044 Peoples R China Zhenjiang Watercraft Coll Dept Phys Zhenjiang 212003 Peoples R China

We study the pulse propagation in a one-dimensional photonic crystal using the finite-difference time-domain method. The wave propagation inside the crystal is the result of superposition of forward and backward waves. We observed the superluminal phenomena and negative values of the velocity of the energy-density maximum. The energy velocities within the crystal never exceed the speed of light in vacuum. We hope that our study contributes to a further understanding of the superluminal phenomena.

关键词： superluminal phenomenon photonic crystal finite-difference time-domain method

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An Accurate Simulator for Magnetic Resonance Coil Sensitivity Estimation

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CONCEPTS IN MAGNETIC RESONANCE PART B-MAGNETIC RESONANCE ENGINEERING 2008年第4期33B卷 209-215页

作者： Giovannetti, Giulio Viti, Vittorio Liu, Yongjun Yu, Wenhua Mittra, Raj Landini, Luigi Benassi, Antonio CNR Inst Clin Physiol Pisa Italy Esaote Biomed Spa Genoa Italy Penn State Univ EE Dept Electromagnet Commun Lab University Pk PA 16802 USA Univ Pisa Dept Informat Engn I-56100 Pisa Italy

Coil sensitivity estimation in magnetic resonance experiments requires the knowledge of biological sample-induced resistance. In dependence on system geometry, many authors studied sample-coil interaction by using a very simple coil geometry (circular, square, etc.) and homogeneous infinitely long cylinders, spheres, or half-spaces as approximations of the sample geometry. However, in real MR experiments, both shape and dimensions can be very different with respect to these coil and sample models. in this article, we propose the application of finite-difference time-domain method for sample-induced resistance estimation. The developed approach can be used as a tool to estimate sample-induced resistance in complex receiving systems, without approximations in sample and coil geometries. Calculation of both sample-induced resistance and magnetic field pattern permits to estimate coil sensitivity for optimal coil design in dependence on the sample size and geometry. Comparison with experimental data, performed on two home-built saddle coils, demonstrated the great accuracy of the developed method. (C) 2008 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 3313: 209-215, 2008

关键词： signal-to-noise ratio sample-induced resistance electromagnetic simulator finite-difference time-domain method coil sensitivity

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Photon confinement in multi-slot waveguides

Photon confinement in multi-slot waveguides

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Conference on Silicon Photonics III

作者： Fu, Yijing Yoo, Han G. Riley, Dan Fauchet, Philippe M. Univ Rochester Inst Opt Rochester NY 14627 USA Univ Rochester Dept Phys & Astron Rochester NY 14627 USA Univ Rochester Dept ECE Rochester NY 14627 USA

ISBN: (纸本)9780819470737

Recent research progress on slot waveguide structures has shown that it is possible to achieve high photon confinement in a low-refractive index region with nanometer thickness. To utilize this photon confinement, we propose a multilayer waveguide that might be the optimum design for future silicon light emission devices. Our device consists of multiple alternating nanometer-thin layers of Si and SiO2 which can be easily fabricated. Both transfer matrix method (TMM) and FDTD simulations are used to simulate the performance of this device. The propagation mode index and photon confinement in SiO2 layers has been calculated. Birefringence as high as 0.8 is achieved with moderate design parameters;although a homogeneous slab waveguide also shows some birefringence, it cannot account for the high birefringence we have calculated. This indirectly indicates that for TM polarization photons are actually confined in the SiO2 layers, where the refractive index is lower. Also our photon confinement simulation shows that, for a structure with multilayer region thickness of 0.52 mu m, photon confinement in SiO2 layers as high as 75% can be achieved with a Si/SiO2 layer thickness ratio close to 1. We fabricated a few multilayer samples with different Si/SiO2 thickness ratios and performed M-line measurement to determine the propagation mode index. The measurement results agree well with our simulation results and also indicate that for TM polarization, photons can be strongly confined within the SiO2 layers in this multilayer structure. Thanks to high confinement in SiO2 layers, this structure could be an excellent choice for future silicon light emitting devices.

关键词： Silicon Waveguides Information operations Birefringence finite-difference time-domain method Photon polarization Polarization Device simulation Light wave propagation Silicon photonics

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Optical phase contrast microscope imaging: a FDTD modeling approach

Optical phase contrast microscope imaging: a FDTD modeling a...

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Saratov Fall Meeting 2009

作者： Tanev, Stoyan Pond, James Paddon, Paul Tuchin, Valery V. Carleton Univ Dept Syst & Comp Engn 1125 Colonel By Dr Ottawa ON K1S 5B6 Canada Lumer Solut Inc Vancouver BC Canada Saratov NG Chernyshevskii State Univ Inst Opt & Biophoton Saratov 410012 Russia RAS Inst Precise Mech & Control Saratov 410028 Russia

ISBN: (纸本)9780819469557

The finite-difference time-domain (FDTD) modeling technique is applied to build a simple simulation equivalent of an optical phase contrast microscope. The model is validated by demonstrating the effect of optical immersion on the optical phase contrast microscope image of a simple biological cell containing a cytoplasm, a nucleus and a membrane. To the best of our knowledge, this is the first study using the FDTD approach to construct optical phase contrast microscope images. The results demonstrate the potential of the FDTD modelling approach and extend its area of applicability a new biomedical research area.

关键词： biological cell finite-difference time-domain method optical phase contrast microscope optical clearing effect

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