Observations of rain depolarization characteristics were conducted using the CS-2 and CS-3 beacon signals (19.45GHz, circular polarization, elevation angle=49.5) during seven years of 1986-1992 at Neyagawa, Osaka. The mean cross-polar phase relative to the co-polar phase of each rainfall event is distributed in a comparatively wide range from -100 to -150. This large variation is suggested to be caused by the difference of raindrop size distribution (DSD) in addition to that of rain intensity. The effects of DSD are examined by rain attenuation statistics for specific months, together with direct measurements of raindrop diameters on the ground for several rainfall events. Compared with representative DSD models, the effects of the Joss-drizzle type with relatively small raindrops primarily appear in "Baiu (Tsuyu)" period, while the effects of the Marshall-Palmer type which represents a standard type are enhanced in "Shurin (Akisame)" period. On the other hand, the effects of the Joss-thunderstorm type with comparatively large raindrops do not indicate a very clear seasonal variation. Possible improvements of XPD performed by differential phase shifters are generally found to be lower than 10dB for the rain depolarization due to the effect of residual differential attenuation after the cancellation of differential phase shift. Such XPD improvements are, however, very sensitive to the type of DSD, and it is suggested that the improvements are at least greater than 6dB for the Joss-drizzle type, whereas they are less than 6dB for the Marshall-Palmer and Joss-thunderstorm types. The effects of the XPD improvements are thus related to rainfall types, i.e., the type of DSD, and the improvements are considerably dependent upon the seasons in which each rainfall type frequently appears.

Automotive electronics technology has become extremely advanced in the regions of automotive engine control, anti-skid brake control, and others. These control systems require highly advanced control performance and high speed microprocessors which can rapidly execute interrupt processing. Automotive engine control systems are now widely utilized in cars with high speed, high power engines. At present, it is generally acknowledged that such high performance engine control for the 10,000 rpm, 12 cylinder engines requires three or more conventional microprocessors. We fabricated an engine control system prototype incorporating the data-driven processor under development, which was installed in an actual automobile. In this paper, the characteristics of the engine control program and simulation results are firstly discussed. Secondly, the structure of the engine control system prototype and the control performance applied to the actual automobile are shown. Finally, from the results of software simulation and the installation of the engine control system prototype with the data-driven processor, we conclude that a single chip data-driven microprocessor can control a high speed, high power, 10,000 rpm, 12 cylinder automobile engine.

The beam propagation method (BPM) is a powerful and manageable method for the analysis of wave propagation along weakly guiding optical waveguides. However, the effects of reflected waves are not considered in the original BPM. In this paper, we propose two simple modifications of the BPM to make it relevant in characterizing abrupt discontinuities in weakly guiding waveguides at which a significant amount of reflection is expected to be observed. Validity of the present modifications is confirmed by the numerical results for abrupt discontinuities in step-index slab waveguides and butt-joints between different slab waveguides.

A best-fit panel model in the radio holographic metrology taking into account locations and sizes of actual surface panels in a large reflector antenna is presented. A displacement and tilt of each panel can be estimated by introducing the best-fit panel model. It was confirmed by simulations that the distinction can be drawn between a continuous surface error and a discontinuous one. Errors due to truncation of the radiation pattern were calculated by simulations. It was found that a measurement of a 128128 map is optimum for the 45-m telescope. The reliability of the measurements using this model was examined by experiments with panel displacements. Panel adjustments using the best-fit panel model successfully improved the surface accuracy of the antenna from 138µm rms to 84µm rms (/D=210-6).

The relation between the radiation pattern and the dimension of the conducting box for a portable telephone is illustrated both theoretically and experimentally. The Galerkin-moment method using the Fourier series expansion for the surface current of the conducting box, which has a great advantage of having a high accuracy, is employed to obtain the radiation pattern. As an example of antennas, a quarter-wavelength monopole antenna having a sinusoidal current distribution is used. As a result, it is pointed out that the radiation pattern of a monopole antenna mounted on the box tends to tilt in a lower direction both in theory and in experiment as well. The relation between the radiation pattern and the location of the monopole antenna is also described. An asymmetrical, or distorted pattern is observed when the monopole antenna moves away from the center of the top plane.

A new superresolution technique is proposed for antenna pattern measurements. Unwanted reflected signals often impinge on the antenna when we measure it outdoors. A time-domain superresolution technique (a MUSIC algorithm) has been proposed to eliminate the unwanted signal for a narrow pass-band antenna. The MUSIC algorithm needs many snapshots to obtain a correlation matrix. This is not preferable for antenna pattern measurements because it takes a long time to obtain the data. In this paper, we propose to reduce a noise component (stochastic quantity) using the FFT and gating techniques before we apply the MUSIC. The new technique needs a few snapshots and saves the measurement time.

The ray-tracing algorithm can synthesize very realistic images. However, the ray tracing is very time consuming. To solve this problem, a load balancing strategy using temporal coherence between images in an animation is presented for balancing computational loads among processing elements of a parallel processng system. Our parallel processing model is based on a space subdivision method for the ray-tracing algorithm. A subdivided object space is distributed among processing elements of the parallel system. To clarify the effectiveness of the load balancing strategy, we examine the system performance by computer simulation.

We propose a recognition method for HMM using a simultaneous generative histogram. Proposed method uses the correlation between two features, which is expressed by a simultaneous generative histogram. Then output probabilities of integrated HMM are conditioned by the codeword of another feature. The proposed method is applied to isolated digit word recognition to confirm its validity.

In this paper, we propose a polynomial time algorithm for computing the expected maximum number of vertex-disjoint s-t paths in a probabilistic basically series-parallel directed graph and a probabilistic series-parallel undirected graph with distinguished source s and sink t(st), where each edge has a mutually independent failure probability and each vertex is assumed to be failure-free.

An electrocardiogram (ECG) data compression algorithm using a polygonal approximation and the template beat variation method (TBV) has been evaluated by reconstruction error and automatic interpretation. The algorithm combining SAPA3 with TBV (SAPA3/TBV) has superior compression performance in PRD and compression ratio. The reconstruction errors, defined as the difference of the amplitude and the time duration between the original ECG and the reconstructed one, are large at waves with small amplitude and/or gradual slopes such as the P wave. Tracing rebuilt from the compressed ECG has been analysed using the automatic interpretative program, and the diagnostic answers with the realated measurements have been compared with the results obtained on the original ECG. The data compression algorithms (SAPA3 and SAPA3/TBV) have been tested on 100 cases in the data base produced by CSE. The reconstruction errors are related to the diagnostic errors. The TBV method suppresses these errors and more than 90% of diagnostic agreements at the error limit of 15µV can be obtained.

The two-dimensional nested cellular automata array presented here as a method for testing CCD arrays accommodates a set of spatial bilateral inhibition and excitation, and thus generates spatio-temporal artificial chaotic signals. Adequate use of the spatio-temporal pulses achieves exact line detection that is completely different from the template-matching scheme used by conventional methods.

The development of highly accurate and durable control system is becoming a must for todays high performance automobiles. For example, it is necessary to up-grade todays materials and methods creating more sensitive sensors, higher speed processors and more accurate actuators, while also being more durable. Thus, the development of a CMOS time-to-digital converter LSI with half-nanosecond resolution, which controls only pulse signals was achieved by employing 1.5 µm CMOS technology. The new signal detecting circuit, 1.1 mm2 in size, converts time to numerical values over a wide measurement range (13 bits). The compact digital circuit employs a newly developed "ring gate delay system". Within the LSI the fully digital circuit is highly durable. This allows it to be utilized even under severe conditions (for example an operating ambient temperature of 130). In order to measure time accurately, a method of correcting the variation of measurement time data employing a real-time conversion fully digital circuit is described. This method allows for fully automatic correction with a microcomputer, so no manual adjustment is required. In addition to sensor circuit applications, the LSI has great potential for Application Specific Integrated Circuit, (ASIC) such as a function cell with is a completely new method of measuring time.

The performances of BPNN (neural network trained by back propagation) and PCANN (neural network which computes principal component analysis) for ECG data compression have been investigated from several points of view. We have compared them with an existing data compression method TOMEK. We used MIT/BIH arrhythmia database as ECG data. Both BPNN and PCANN showed better results than TOMEK. They showed 1.1 to 1.4 times higher compression than TOMEK to achieve the same accuracy of reproduction (13.0% of PRD and 99.0% of CC). While PCANN showed better learning ability than BPNN in simple learning task, BPNN was a little better than PCANN regarding compression rates. Observing the reproduced waveforms, BPNN and PCANN had almost the same performance, and they were superior to TOMEK. The following characteristics were obtained from the experiments. Since PCANN is sensitive to the learning rate, we had to precisely control the learning rate while the learning is in progress. We also found the tendency that PCANN needs larger amount of iteration in learning than BPNN for getting the same performance. PCANN showed better learning ability than BPNN, however, the total learning cost were almost the same between BPNN and PCANN due to the large amount of iteration. We analyzed the connection weight patterns. Since PCANN has a clear mathematical background, its behavior can be explained theoretically. BPNN sometimes generated the connection weights which were similar to the principal components. We supposed that BPNN may occasionally generate those patterns, and performs well while doing that. Finally we concluded as follows. Although the difference of the performances is smal, it was always observed and PCANN never exceeded BPNN. When the ease of analysis or the relation to mathematics is important, PCANN is suitable. It will be useful for the study of the recorded data such as statistics.

For analyzing the transient electromagnetic fields caused by electrostatic discharge (ESD), a new ESD model is presented here. Numerical calculation is also given to explain the distinctive phenomenon being well-recognized in the ESD event.

The finite-difference beam-propagation method is applied to the analysis of hollow slab waveguides (HSWs). The attenuation constants for the TE0 and TE1 modes are evaluated and compared with those obtained by the perturbation theory. The propagating field and differential power loss in the transition from a straight HSW to a bent HSW are revealed and discussed.

Numerical analysis of the electromagnetic radiation from conducting surface structures is concerned. The method of moments is discussed with the surface-patch modeling in which the surface quantities, i.e. the current, charge and impedance are directly introduced and with the wire-grid modeling in which the surface quantities are approximated by the filamentary traces. The crucial element to a numerical advantage of the wire-grid modeling lies in the simplicity of its mathematical involvements that should be traded for the uncertainties in the construction of the model. The surface-patch techniques are generally not only clear and straightforward but also more reliable than the wire-grid modeling for the computation of the surface quantities. In this work, we bring about a comparative discussion of the two approaches while the analysis of a built-in planar antenna is reported. For the purpose of the comparison, the same electric field integral equation and the Galerkin's procedure with the linear expansion/testing functions are used for both the wire-grid and surface-patch modeling.

A quick evaluation method is proposed to obtain stability robustness measures in polynomial coefficient space based on knowledge of coefficients of a Hurwitz stable nominal polynomial. Two norms are employed: l- and l2-norm, which correspond to the stability hypercube and hyperball in the space, respectively. Just inverting Hurwitz matrix for the nominal polynomial immediately yields closed-form estimates for the size of the hypercube and hyperball.

To make a fast Bi-CMOS SRAM yield high without speed degradation, three defect-repair methods, the address comparison method, the fuse decoder method and the distributed fuse method, were considered in detail and their advantages and disadvantages were made clear. The distributed fuse method is demonstrated to be further improved by a built-in fuse word driver and a built-in fuse column selector, and fuse analog switches. This enhanced distributed fuse scheme was examined in a fast Bi-CMOS SRAM. A maximun access time of 14 ns and a chip size of 8.8 mm17.4 mm are expected for a 4 Mb Bi-CMOS SRAM in the future.

This paper presents a parallel sorting algorithm which sorts n elements on O(n/w+n log n/p) time using p(n) processors arranged in a 1-dimensional grid with w(n1-ε) buses for every fixed ε>0. Furthermore, it is shown that np elements can be sorted in O(n/w+n log n/p) time on pp (pn) processors arranged in a 2-dimensional grid with w(n1-ε) buses in each column and in each row. These algorithms are optimal because their time complexities are equal to the lower bounds.

This paper describes a novel method to calculate the fields scattered by a polyhedron structure for an incident plane wave. In this method, the fields diffracted by an edge are calculated using the equivalent edge currents which are separated into components dependent on each of the two surfaces which form the edge. The separated equivalent edge currents are based on the Geometrical Theory of Diffraction (GTD). Using this Separated Equivalent Edge Current Method (SEECM) , fields scattered by a polyhedron structure can be calculated without special treatment of the singularity in the diffraction coefficient. This method can be also applied successfully to structures with convex surfaces by modeling them as polyhedron structures.