The electromagnetic scattering of a plane wave by an inhomogeneous plane whose surface impedance changes locally on the plane is treated. A boundary-value problem is formulated to describe the scattering phenomenon, in which the boundary condition depends on the surface impedance of the plane. Application of the Fourier transform derives an integral equation, which is approximately solved by the method of least-squares. From the solution of the equation, the scattered field is obtained by the inverse Fourier transform. By the use of the incomplete Lipschitz-Hankel integral for the computation of the field, numerical examples are given and the scattering phenomenon is discussed.

We propose a simple method for the chromatic dispersion measurement of optical fibers by using bi-directional modulation of a Mach-Zehnder electro-optical modulator embodied in a fiber loop mirror. The detected output of the bi-directionally modulated light, with time difference, creates fading in the RF domain. Dispersion is found by measuring the period of fading at different wavelengths.

In this paper, we propose a new region extraction method with a chromakey technique using a two-tone striped background. A chromakey compositing is a technique for separating actors or actresses from a background, and then compositing a different background. The conventional chromakey technique usually uses an unicolored blue or green background, and has a problem that one's clothes are regarded as the background if their colors are same with the background's color. Therefore, we use two-tone striped background and utilize the adjacency condition between two-tone striped areas on the background to extract the foreground regions whose colors are same with the background. The procedure of our proposed method consists of four steps: 1) background color extraction, 2) striped region extraction, 3) foreground extraction, and 4) image composition. As to the background color extraction, the color space approach is used. As to the striped region extraction, it is difficult to extract striped region by a color space approach because the color of this region may be a composite of two background colors and different from them. Therefore, the striped region is extracted from adjacency conditions between two background colors. As to the foreground extraction, the boundary between the foreground and the background is detected to recheck the foreground region whose color is same as the background, and the background region whose color is same as the foreground. To detect the region whose color is same as the background, the adjacency conditions with the striped region are utilized. As to the image composition, the process that smoothes the color of the foreground's boundary against the new background is carried out to create natural images. The validity of proposed method is shown through experiments with the foreground objects whose color is same as the background color.

This paper presents new results in the field of very low bitrate coding and compression using 3D informations. Contrary to prior art in model-based coding where 3D models have to be known, the 3D models are automatically computed from the original video sequence. The camera parameters and the scene content are supposed unknown and the video sequence is processed on the fly. A stream of 3D models is then extracted and compressed, using adapted compression techniques. We finally show the results of the proposed compression scheme, and the efficiency of this approach.

We propose a new method for Depth from Defocus (DFD) using wavelet transform. Most of the existing DFD methods use inverse filtering in a transform domain to determine the measure of defocus. These methods suffer from inaccuracies in finding the frequency domain representation due to windowing and border effects. The proposed method uses wavelets that allow performing both the local analysis and windowing with variable-sized regions for images with varying textural properties. Experimental results show that the proposed method gives more accurate depth maps than the previous methods.

The classic light field and lumigraph are two well-known approaches to image-based rendering, and subsequently many new rendering techniques and representations have been proposed based on them. Nevertheless the main limitation remains that in almost all of them only static scenes are considered. In this contribution we describe a method for calibrating a scene which includes moving or deforming objects from multiple image sequences taken with a hand-held camera. For each image sequence the scene is assumed to be static, which allows the reconstruction of a conventional static light field. The dynamic light field is thus composed of multiple static light fields, each of which describes the state of the scene at a certain point in time. This allows not only the modeling of rigid moving objects, but any kind of motion including deformations. In order to facilitate the automatic calibration, some assumptions are made for the scene and input data, such as that the image sequences for each respective time step share one common camera pose and that only the minor part of the scene is actually in motion.

In this paper, we present a numerical analysis for resonant characteristics of the TM010 mode of a cylindrical cavity containing a dielectric rod and a conductive layer on its metal walls. This analysis uses the mode matching method for calculation. Error in complex permittivity of a loaded dielectric rod measured using a layered cavity is evaluated as a function of thickness and layered conductor conductivity. A thick layered cavity is necessary for precise measurement of material properties using the cavity resonator method at microwave and millimeter-wave frequencies.

In this paper, we calculated resonant frequency and unloaded Q-factor for the TM0i0 resonant mode excited in a cylindrical cavity composed of walls with finite conductivity and with a dielectric rod loaded coaxially along the central axis. Formulation for the calculation is made using the mode-matching method. Convergence of the calculation is checked. Values calculated by the present method for various combinations of dimensions, permittivity, and conductivity of the inner-components of cavity are compared with those calculated by a conventional method formulated using loss-less electromagnetic fields of cavity. Although the difference between the values calculated by those two methods is usually small, it is found that the difference increases as permittivity of dielectric rod increases and becomes about 10-6 in reciprocal of unloaded Q-factor of the loaded cavity in a presented case.

Making up an electromagnetic wave simulator based on the FEM is tried, which may run on some widely used platforms by use of Java and a single commercial tool. Since the codes and configuration files to be created for this simulator are common, one can construct the simulator running on the platforms at the same time. Using this simulator, the transmission properties of two- and three-dimensional waveguide discontinuities in optical and microwave waveguides are analyzed, the inverse problem in material constant measurement is solved, and the computed results are presented including plots of the electric field distribution.

The transient phenomenon of electromagnetic waves caused by a time dependent resistive screen in a waveguide is treated. A boundary-value problem is formulated to describe the phenomena, in which the resistivity of the screen varies from one steady state to another in dependence on time. Application of Fourier analysis derives an integral equation, which is approximately solved by the method of least-squares. From the solution of the equation, the transient field is obtained by the inverse Fourier transform. By the use of the incomplete Lipschitz-Hankel integral for the computation of the field, numerical examples showing typical transient phenomenon are attached.

In this paper a second order Volterra series model of an operational amplifier (opamp) circuit is presented. Such a model is suitable to the investigation of the rectification and demodulation effects of radio frequency (RF) interference superimposed on the nominal input signals and on the power supply voltage of an opamp. On the basis of the new model, some design criteria to improve the immunity of opamps to RF interference are proposed. Model predictions are verified by comparison with experimental test results.

As the capacity of a personal computer and workstation increases rapidly, many electromagnetic simulators solving antenna problems are widely used. In this paper, the IE3D, FIDELITY and HFSS electromagnetic simulators, which are commercial software products, are applied to the analysis of built-in antennas for handsets in the vicinity of the human body. The IE3D, FIDELITY and HFSS electromagnetic simulators are based on the methods of moment, FDTD (Finite Difference Time Domain) and FEM (Finite Element Method), respectively. Firstly, basic characteristics including the human body's effect of a popular built-in antenna for handset such as PIFA (Planar Inverted-F Antenna) are obtained by the IE3D, FIDELITY and HFSS electromagnetic simulators, and calculated results are compared with measured results. Secondly, on the basis of newly considered design concepts for a handset antenna, a folded loop antenna for handset, which we have proposed in order to reduce the influence of the human body, is taken as an example of a balance-fed antenna and is analyzed theoretically and experimentally including the influence of the human body. In a result, calculated results by these three kinds of electromagnetic simulators are in good agreement with measured results and it is confirmed that these simulators are very effective in analyzing the handset antenna in the vicinity of the human body.

The boundary element method (BEM), a representative method of numerical calculation of electromagnetic wave scattering, has been used for solving boundary integral equations. Using BEM, however, we finally have to solve a linear system of L equations expressed by dense coefficient matrix. The floating-point operation is O(L2) due to a matrix-vector product in iterative process. Greengard-Rokhlin's fast multipole algorithm (GRFMA) can reduce the operation to O(L). In this paper, we describe GRFMA and its floating-point operation theoretically. Moreover, we apply the fast Fourier transform to the calculation processes of GRFMA. In numerical examples, we show the experimental results for the computation time, the amount of used memory and the relative error of matrix-vector product expedited by GRFMA. We also discuss the convergence and the relative error of solution obtained by the BEM with GRFMA.

Electromagnetic shielding clothes for reducing human exposure to radio waves have been commercialized. However, their effect has so far been confirmed only in the form of the raw material. In this paper, we develop a new compact scheme for measuring electromagnetic radiations using a short dipole antenna and Gaussian pulses in order to evaluate the effect of the shielding clothes over a wide frequency range with the aid of time-domain measurements and FDTD computation. The proposed method is based on a time-domain analysis technique and pulse compression technique, which enables the user to separate the direct transmission wave from the reflection from the floor as well as from the refracted wave around the neck of the clothes. The direct advantage is that measurements can be made in an ordinary laboratory without the function of an electromagnetic anechoic chamber. Also, we can separate direct transmission wave and diffraction wave from the measurement result by using pulse compression technique, then each frequency characteristic of the shielding shirt can be evaluated. The performance of the separation is confirmed by comparing the measurements with those of a shirt with no opening. We further demonstrate the possibility of predicting the effective conductivity of the material as a function of frequency by comparing the measured results with realistic FDTD computations, which will enable us to design a shielding shirt via numerical means.

In this paper, we proposed the doubly tapered electromagnetic periodic structure (DT-EPS) bandstop filters in coplanar waveguide (CPW) and cylindrical coplanar waveguide (CCPW). The DT-EPS bandstop filter not only can effectively improve the stopband rejection but also increase its bandwidth. In addition, this technique can significantly reduce the passband ripples compared with conventional case.

We investigate the statistical features of both random- and chaos-based FM timing signals to ascertain their applicability to digital circuits and systems. To achieve such a goal, we consider both the case of single- and two-phase logic and characterize the random variable representing, respectively, the time lag between two subsequent rising edges or between two consecutive zero-crossing points of the modulated timing signal. In particular, we determine its probability density and compute its mean value and variance for cases which are relevant for reducing Electromagnetic emissions. Finally, we address the possible problems of performance degradation in a digital system driven by a modulated timing signal and to cope with this we give some guidelines for the proper choice of the statistical properties of the modulating signals.

In this work, micromagnetic simulations of writing and reading processes in a perpendicular system including a single pole head and recording media with soft underlayer (SUL) have been performed. The noise contribution from the recording layer increased with increasing grain size distribution of the recording layer but that from soft underlayer remained almost a constant at a given linear density. Details of the noise from the soft underlayer will be discussed. Also thermal decay over a long time scale of the recorded bits was investigated by the Langevin equation and the time-temperature scaling method. It was found that at the linear density of 1058 kfci narrower grain size distribution in the recording layer even in the same average grain size is very important in the point of thermal decay than expectation.

An analysis method based on the FD-TD and radiation mode expansion methods and its simulation tool are developed for calculating circuit characteristics and parameter values of passive MMIC (Monolithic Microwave Integrated Circuits) elements having multilayer structure. For straight multilayer microstrip lines and coplanar waveguides, it is possible to calculate characteristic impedance, effective permittivity, transverse field distribution of guided modes, etc. For various multilayer microstrip and coplanar waveguide elements, it is possible to calculate scattering parameters, radiated power, radiation patterns, etc. As an example of application of the present technique, effects of inclusion of lower permittivity layer in the substrate on transmission and radiation characteristics are investigated for right-angled microstrip bends.

So far, a lot of analyses have been performed on the edge-guide mode isolator with one short edge. However, the detailed characteristics such as the influence of shape of a metal strip and the thickness of a ferrite substrate have not been revealed. This paper clarifies the influence of the structure on the frequency response both experimentally and numerically. The numerical analysis is performed by the FDTD method. The numerical results indicate that the frequency response does not depend on the thickness of ferrite substrate but does on the shape of the metal strip. Furthermore, based on the numerical results, the experiment is carried out on the prototype isolator. All the results provide a theory of the optimum design on the isolator.

It is known that Viterbi decoding based on the code trellis and syndrome decoding based on the syndrome trellis (i.e., error trellis) are equivalent. In this paper, we show that Scarce State Transition (SST) Viterbi decoding of convolutional codes is equivalent to syndrome decoding. First, we derive fundamental relations between the hard-decision input to the main decoder and the encoded data for the main decoder. Then using these relations, we show that the code trellis module for the main decoder in an SST Viterbi decoder can be reduced to a syndrome trellis module. This fact shows that SST Viterbi decoding based on the code trellis is equivalent to syndrome decoding based on the syndrome trellis. We also calculate the SST Viterbi decoding metrics for general convolutional codes assuming an AWGN channel model. It is shown that the derived metrics are equal to those of conventional Viterbi decoding. This fact shows that SST Viterbi decoding is equivalent to conventional Viterbi decoding, and consequently to syndrome decoding.