C-axis junction-arrays, with a-b plane sizes of sub-microns to 10 microns, were patterned on Bi2Sr2CaCu2O8+x single crystals with either a mesa or an overlap structure. We measured the current-voltage (I-V) characteristics with microwave irradiation at a few to 100 gigahertz. At a few gigahertz, often observed were chaotic properties. Under irradiation at 100 GHz, we successfully performed harmonic mixings between the 100 GHz signal and up to the 100th harmonic of a local oscillator at about 1 GHz. Given in this paper are discussions on the observation of individual Shapiro steps, and descriptions of the relevant results. Our experimental results show that intrinsic Josephson junctions in layered superconductors can be good candidates for high frequency applications.

The micro positioning systems using magnetic suspension technique, which is one of precision actuating method, have been suggested. Utilizing the various potentials such as the exclusion of a mechanical friction, they are being applied broadly to multi degrees of freedom (d.o.f) system requesting high accuracy or hybrid system requesting to be controlled position and force simultaneously. This paper presents the entire development procedure of a novel six d.o.f micro positioning system using mag-netic levitation, with a repulsive force mechanism covering the all d.o.f. First, the interactions between magnetic elements are modeled and the system design flow by an optimal location of the elements is given. A kinematic relationship between the measuring instruments and the levitated object is derived, and dynamic characteristics are identified by the narrow gap principles. And the main issues for control are discussed.

Based on the systematic block codes, we propose a (t,n) multi-secret sharing scheme. Compared with the previous works, our scheme has the advantages of smaller communication overhead, easy generator matrix construction and non-disclosure of users secret shares after multiple secret reconstruction operations. These advantages make the practical implementation of our scheme very attractive.

A program is developed to simulate the signal received by a bistatic pulse radar for a defined scenario. The signal collected at the receiving antenna is calculated as a function of time by taking into account the vectorial aspect of the electromagnetic waves and various elements operating in the radar radiolink. The radar radiolink is designed in a modular structure for a general configuration where the transmitter, the target and the receiver are moving. Modules such as elements characterizing the antennas radiation or defining the target scattering can be inserted in accordance with the desired radar scenario. Then the developed model permits to simulate a wide range of radar scenarios where returns from targets and clutter can be individually processed and their characteristics can be investigated in time or frequency. The interest of this model is great because it permits, for a defined scenario, to generate radar data which can be used in signal processing algorithms for target detection, clutter suppression or target classification. This paper shows the implementation of the simulation program considering a concrete radar scenario. The presented scenario deals with the simulation of the sea clutter occurring in a bistatic radar radiolink over the sea surface. In this application where the sea surface is considered as the target, the electric field scattered from the sea surface is calculated by assuming that the surface is described by two independent scales of roughness.

The subject of this study is to propose a new structure that can realize simultaneously high breakdown voltage and high packing density for both Nch low side switch and Pch high side switch in 200 V class rating. As the conventional techniques for the electric field relaxation, the structure of field plate, field ring and RESURF are well known, but these techniques are inadequate for the high packing density because they are the techniques in surface region. In order to conquer this subject, it is necessary to relax the electric field in the deep region. The electric field relaxation was investigated by device simulation. In the Nch low side switch the electric field is relaxed by buried oxide film in SOI structure. However, electric field relaxation cannot be realized only by adapting the SOI structure for Pch high side switch. Then we tried to insert an intrinsic layer between P-drift layer and the buried oxide film in order to spread the depletion layer in the deep region. This spread depletion layer by intrinsic layer and the depletion layer by field plate connect vertically, and the dosage of the ion implantation for drift layer can be set to two times higher than the case without intrinsic layer. As the results, it was revealed that the SOI structure with intrinsic layer is effective to achieve this subject. Furthermore, by fabricating both Nch low side switch and Pch high side switch on intrinsic SOI substrate, breakdown voltage more than 250 V were achieved.

A Generalized Hypercube Network (GHNet) with shared channels which requires only one fixed-wavelength transmitter and r(m-1) fixed-wavelength receivers per node is proposed. The proposed network topology reduces not only the number of transmitters per node but also the number of WDM channels required to service the same number of nodes compared with the GHNet with dedicated channels by sharing the available WDM channels, while it maintains the same channel efficiency as the GHNet with dedicated channels. The proposed network topology may be preferred in a situation where the number of available WDM channels and the cost of the transmitter may cause a major restriction on the lightwave network construction. For performance analysis, the network capacity and the mean queueing delay for the proposed network topology are obtained. Also, the performance measures of the proposed GHNet with shared channels are compared with those of the ShuffleNet with shared channels.

A novel technique is developed to reconstruct a nonuniform transmission line by using arbitrary incident waveforms. By discretizing both the incident and reflected waves, we find that the ratio of reflected wave to incident wave has the same form as the reflection coefficient obtained by treating a nonuniform line as a cascaded, multiple-section signal line. A reconstruction scheme is derived to get the impedance profile of a nonuniform line. Some examples are presented to illustrate this new technique.

Causal message ordering in the context of group communication ensures that all the message receivers observe consistent ordering of events affecting a group as a whole. This paper presents a scalable causal multicast protocol for mobile distributed computing systems. In our protocol, only a part of the mobility agents in the system is involved in group computations and the resulting size of control information in messages can be kept small. Our protocol can outperform qualitatively the counterparts in terms of communication overhead and handoff complexity. An analytical model is also developed to evaluate our proposal. The performance results show that the proposed protocol is promising.

In this paper we have presented a new method for seismic signal analysis, based on the ARMA modeling and a fuzzy LVQ clustering method. The objective achieved in this work is to sense the changes made naturally or artificially on the seismogram signal, and to detect the sources, which caused these changes (seismic classification). During the study, we have also found out that the model is sometimes capable to alarm the further seismic events just a little time before the onset of those events (seismic prediction). So the application of the proposed method both in seismic classification and seismic prediction are studied through the experimental results. The study is based on the background noise of the teleseismic short period recordings. The ARMA model coefficients are derived for the consecutive overlapped windows. A base model is then generated by clustering the calculated model parameters, using the fuzzy LVQ method proposed by Nassery & Faez in [19]. The time windows, which do not take part in [19] model generation process, are named as the test windows. The model coefficients of the test windows are then compared to the base model coefficients through some pre-defined composition rules. The result of this comparison is a normalized value generated as a measure of similarity. The set of the consecutive similarity measures generate above, produce a curve versus the time windows indices called as the characteristic curves. The numerical results have shown that the characteristic curves often contain much vital seismological information and can be used for source classification and prediction purposes.

This paper deals with the scattering problem of a layer where many spherical lossy particles of high dielectric constant are randomly distributed. A radiative transfer equation is used to calculate the scattering cross section of the layer. Four different multiple scattering methods are applied to determine the coefficients of the equation. The scattering cross sections of the four methods are compared by changing the incident angle and polarization of incident waves and the layer thickness. The comparison shows that the scattering cross section fairly depends on the multiple scattering methods and that we need to use an appropriate multiple scattering method for a scattering problem when using a radiative transfer equation.

A two-dimensional algorithm, which combines the well-known Synthetic Aperture Radar (SAR) imaging and the recently developed effective inversion method, is presented and applied to a three-dimensional configuration. During the first stage a two-dimensional image of a realistic three-dimensional buried object is obtained. In the second stage the average permittivity of the object is estimated using a two-dimensional effective inversion scheme where the geometrical information retrieved from the SAR image is employed. The algorithm is applicable in real time.

Aged people who live alone are in particular need of a daily health check, medication, and of warm communication with family and friends. The authors have been developing a life-support computer system with such functions. Among them, a daily health check function with the capability of measuring blood pressure, detecting diseases from coughing, and so on would in particular be very powerful for primary care. As a first step to achieving quick services for a daily health check with a personal computer, utilization of cough information is considered. Features of cough data are analyzed aiming at developing an automatic cough data detection method. This paper proposes a novel method for extracting cough signals from other types of signals. The differential coefficient of a low-pass filtered waveform is first shown to be an effective parameter for discriminating between vowel and cough signals, and the relationship between cut-off frequency and cough detection rate is clarified. This parameter is then applied to cough signals mixed with vowel signals or white noises to evaluate robustness. The evaluation tests show that the cough feature can be perfectly detected for a 20 dB S/N ratio when the cut-off frequency is set to 24 [Hz]. The experimental results suggest that the proposed cough detection method can be a useful tool as a primary care for aged people with a bronchitis like an asthmatic bronchitis and a bronchopneumonia.

An averaged intensity peak profile of light scattered from a random medium depends on a thickness of a sample as well as parameters such as a volume fraction and a size of particles composing the medium. We used this dependence to measure a depth profile varied in the random medium. We demonstrated the possible simultaneous measurement of a transport mean free path and a depth of an aqueous suspension of titanium particles.

An inverse scattering problem in three dimensional two layered media is investigated. The shape and the location of the acoustic scatterer buried in one half-space are determined. With some a priori information, it becomes possible to solve this problem in three dimensions. Using the moment method, the scattered field is obtained for the estimated scatterer. An iterative procedure based on the Newton's method for the nonlinear least square problem is able to solve the inverse scattering problem. Some numerical results are presented.

A signal processing approach is discussed which has the potential for imaging strongly scattering objects from a series of scattering experiments. The method is based on a linear spectral estimation technique to replace the filtered backpropagation for limited discrete data and a subsequent nonlinear signal processing step to remove the contribution of multiple scattering my means of homomorphic filtering. Details of this approach are discussed and illustrated by applying the imaging algorithm to both simulated and real data.

To make clear numerically the scattering characteristics for a body embedded in a random medium, we need to analyze the bistatic cross-section (BCS). The scattering problem can be analyzed as a boundary value problem by using current generator method. The fourth moment of Green's functions in the random medium, which is necessary for the analysis, is obtained approximately by two-scale method. We analyze numerically the BCS of conducting circular cylinders in continuous random media, which are assumed to fluctuate about the dielectric constant of free space. The numerical results agree well with the law of energy conservation. The effects of random media on the BCS are also clarified numerically.

The mean reflection and transmission coefficients of electromagnetic waves incident onto a two-dimensional slightly random dielectric surface are investigated by means of the stochastic functional approach. We discuss the shift of Brewster's scattering angle using the Wiener kernels and numerical calculations. It is also shown that the phase shift at the reflection into Brewster's angle for a flat surface does not depend on the rms height of the surface, but does on the correlation length of the surface.

In this paper, the electromagnetic scattering from a cylinder with a computer-generated random rough surface is analyzed by a numerical simulation method. The validity of the proposed numerical method is confirmed by comparing the present numerical results with those calculated by the perturbation method to second order and its Pade approximation. It is shown that the present proposed method can be applied to the case where the surface roughness becomes relatively large.

The finite volume time domain (FVTD) method is applied to electromagnetic wave scattering from random rough dielectric surfaces. In order to gain a better understanding of physics of backscattering of microwave from rough surface, this paper treats both horizontal and vertical polarizations especially at low- grazing angle. The results are compared with those obtained by the Integral equation method and the small perturbation method as well as with the experimental data. We have shown that the present method yields a reasonable solution even at LGA. It should be noted that the number of sampling points per wavelength for a rough surface problem should be increased when more accurate numerical results are required, which fact makes the computer simulation impossible at LGA for a stable result. However, when the extrapolation is used for calculating the scattered field, an accurate result can be estimated. If we want to obtain the ratio of backscattering between the horizontal and vertical polarization, we do not need the large number of sampling points.

In this paper we report the results of a study regarding the backscattering from wind-roughened water surfaces. The reference profile data has been deducted by an experiment held at the University of Heidelberg circular wave tank facility. The scattering theory is based on a fractal description of the surface and a combined use of the Kirchhoff approximation and the small perturbation method (SPM). The scattering results are tested versus the ones obtained via the periodic-surface moment method. The study shows the reliability of the novel approach.