Analysis of wave propagation on human body based on stratified media model

Human body communication(HBC) is a promising near-field communication(NFC) method emerging in recent years. But existing theoretical models of HBC are too simple to simulate the wave propagation on human body. In this work, in order to clarify the propagation mechanism of electromagnetic wave on human body, a surface waveguide HBC theoretical model based on stratified media cylinder is presented. A numerical model analyzed by finite element method(FEM) is used for comparing and validating the theoretical model. Finally, results of theoretical and numerical models from 80 MHz to 200 MHz agree fairly well, which means that theoretical model can characterize accurate propagation mechanism of HBC signal. Meanwhile, attenuation constants derived from two kinds of models are within the range from 1.64 to 3.37, so that HBC signal can propagate effectively on human body. The propagation mechanism derived from the theoretical model is useful to provide design information for the transmitter and the modeling of the propagation channel in HBC.

Propagation and Attenuation Characteristics of Diesel Particulate Filter

Diesel particulate filter (DPF) is an important factor which influences the sound from exhaust system of an engine. In order to understand the propagation law of sound wave and predict the insertion loss in DPF, based on the general aero-dynamic equations and Darcy′s law, an acoustic property calculation model of DPF is constructed. Propagation and attenuation characteristics of the forward and backward propagating acoustic waves in the close and open pipe of the filter are investigated. The theoretical model is combined with experiment to investigate sound attenuation property of DPF. The insertion loss obtained from the experiment is compared with that computed for a DPF. The results from the experiment and theoretical calculation agree well.

COMPACT FOUR-COMPONENT 2-D FDFD METHOD WITH EQUIVALENT SURFACE IMPEDANCE BOUNDARY CONDITION FOR MULTILAYER METAL-COATED WAVEGUIDE

A compact four-component two-dimensional （2-D） finite-difference frequency domain （FDFD） method with the equivalent surface impedance boundary condition is used to analyze the dispersion characteristics of multilayer metal-coated waveguides. According to the equivalent surface impedance boundary condition,the relationship between transverse field components on the boundary can be easily depicted. Once the eigen equation is solved,the propagation constant can be obtained as the eigen value for a given frequency. Results of the proposed method agaree well with those of high frequency structure simulator（HFSS）.

周期金属栅加载非辐射介质波导传输特性的分析

近年来,非辐射介质波导(NRD)传输特性、衰减特性、耦合特性和不连续性等的研究越来越受到人们的重视,并用之研制了滤波器、定向耦合器、振荡器和漏波天线等许多微波与毫米波元器件。现在人们正在为研制毫米波全NRD波导系统而努力。在研制NRD波导元部件的过程中,当遇到非对称不连续性时,由于LSE_(11)模的存在,元部件的指标将受到严重的影响。为了抑制LSE_(11)模的产生,在文[10]中使用了金属薄片,但是还未看到利用集成在NRD波导上的金属薄片构成微波与毫米波元件的报导。

Investigation on Transmission Properties of Terahertz Wave Through Semiconductor Aperture

The transmission properties of terahertz （THz） wave passing through semiconductor aperture have been investigated. The dispersion relationship for surface plasmon polariton （SPP） at different temperatures has been numerically calculated. The results show that the dispersion relationship increases with the increasing of frequency and the decreasing of temperature, the thickness of slab has to be taken into consideration because of the large skin depth for semiconductor slab. In addition, the propagation constant increases with the increasing of frequency and the decreasing of temperature.

Interesting effects in harmonic generation by plane elastic waves

The harmonics of plane longitudinal and transverse waves in nonlinear elastic solids with up to cubic nonlinearity in a one-dimensional setting are investigated in this paper. It is shown that due to quadratic nonlinearity, a transverse wave generates a second longitudinal harmonic.This propagates with the velocity of transverse waves, as well as resonant transverse first and third harmonics due to the cubic and quadratic nonlinearities. A longitudinal wave generates a resonant longitudinal second harmonic, as well as first and third harmonics with amplitudes that increase linearly and quadratically with distance propagated. In a second investigation, incidence from the linear side of a primary wave on an interface between a linear and a nonlinear elastic solid is considered. The incident wave crosses the interface and generates a harmonic with interface conditions that are equilibrated by compensatory waves propagating in two directions away from the interface. The back-propagated compensatory wave provides information on the nonlinear elastic constants of the material behind the interface. It is shown that the amplitudes of the compensatory waves can be increased by mixing two incident longitudinal waves of appropriate frequencies.

Propagating Characteristics of Confocal Elliptical Waveguide Filled with Multilayered Dielectrics

Using the method of separation of variables in the elliptical coordinate system, a recursive formula for the electromagnetic fields in a confocal elliptical waveguide filled with multi-layered homogeneous isotropic media is derived; then the eigenequation for it is given. When an elliptical waveguide becomes a circular waveguide, the electromagnetic fields and the eigenequation of the circular waveguide can be obtained from the eigenequation of the elliptical waveguide using the asymptotic formulae of Mathieu and modified Mathieu functions for a large radial coordinate in the elliptical coordinate system, and the eigenequation of a circular waveguide filled with multilayered dielectrics can be treated as a special case of an elliptical waveguide. In addition, some numerical examples are presented to analyze the propagating characteristics influenced by the permittivity, permeability of dielectrics filled in the elliptical waveguide, etc. The results show that changing the permittivity or permeability of the dielectrics filled in the waveguide and the major semiaxis value of the i-th layer can change the propagating characteristics of an elliptical waveguide.

Interprocedural Constant Range Propagation and Alias Analysis by Multiple Version Method

A set of methods for interprocedural analysis is proposed. First, an ap-proach for interprocedural constant propagation is given. Then the concept of constant propagation is extended so as to meet the needs of data dependence analysis. Besides certain constant, constant range can also be propagated. The related propagating rules are introduced, and an idea for computing Return function is given. This approach can solve almost all interprocedural constant propagation problems with non-recursive calls. Second, a muItiple-version par-allelizing technique is also proposed for alias problem. The work related to this paper has been implemented on a shared-memory parallel computer.

Electrical analysis of single-walled carbon nanotube as gigahertz on-chip interconnects

The single-walled carbon nanotube （SWCNT） is a promising nanostructure in the design of future high- frequency system-on-chip, especially in network-on-chip, where the quality of communication between intellectual property （IP） modules is a major concern. Shrinking dimensions of circuits and systems have restricted the use of high-frequency signal characteristics for frequencies up to 1000 GHz. Four key electrical parameters, impedance, propagation constant, current density, and signal delay time, which are crucial in the design of a high-quality interconnect, are derived for different structural configurations of SWCNT. Each of these parameters exhibits strong dependence on the frequency range over which the interconnect is designed to operate, as well as on the configuration of SWCNT. The novelty of the proposed model for solving next-generation high-speed integrated circuit （IC） interconnect challenges is illustrated, compared with existing theoretical and experimental results in the literature.