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.

Some results are presented of a one-year measurement period on an INTELSAT down link at Ku band with elevation of 14 for concurrent measurements of beacon attenuation, sky noise and point rainfall rate. Also some results are presented of line-of-sight (LOS) link fading characteristics at the same place. The projection of the down link trajectory on earth has nearly the same direction as the LOS path trajectory. The measurement results are compared with the theoretical values according to the CCIR recommended procedures of rain attenuation predictions for tropical regions, especially Surabaya, Indonesia. A record rain attenuation value of 80dB was observed.

A 10 GHz MMIC predistortion linearizer fabricated on a single chip is demonstrated for the first time. It employs less hybrid circuits compard with conventional devices, and is suitable for miniaturization. The total chip size of the fabricated MMIC is about 3.5 mm3.0 mm. The distortion reduction effect is examined using this linearizer. The improvement in IM3 is more than 15 dB between 10.45 GHz and 10.70 GHz, and more than 8 dB between 10.05 GHz and 10.90 GHz.

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.

A two-dimensional quasi-exact active imaging method for detecting the conducting objects buried in a dielectric half-space is proposed. In this imaging method, an image function which is a projection of buried object to an arbitrary direction, is introduced exactly by taking account of the presence of the planar boundary. The image function is synthesized from the scattering fields which are measured by moving a transmitting antenna (a current source) and a receiving antenna (an observation point) simultaneously along the ground surface. The scattering field is generated by the physical optics current assumed on the surface of buried object. Because the effectiveness of physical optics approximation has been confirmed for this problem, this is a quasi-exact active imaging method. The validity of this imaging method is confirmed by some numerical simulations and an experiment.

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 article, the autocorrelation associative neural network that is one of well-known applications of neural networks is improved to extend its capacity and error correcting ability. Our approach of the improvement is based on the consideration that negative self-feedbacks remove spurious states. Therefore, we propose a method to determine the self-feedbacks as small as possible within the range that all stored patterns are stable. A state transition rule that enables to escape oscillation is also presented because the method has a possibility of falling into oscillation. The efficiency of the method is confirmed by means of some computer simulations.

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.

Electromagnetic plane wave scattering by a wide trough on the ground has been analyzed by high frequency asymptotic techniques based on Geometrical Theory of Diffraction. Field in the trough region has been formulated in terms of parallel plane waveguide modes, whose excitation (coupling) coefficients are obtained by ray-mode conversion techniques. Numerical calculation has been done extensively and thus obtained results are then compared with those by other methods. Good agreements have been observed except for oblique incidence case. It is found that first and secondary modal re-radiation fields from the indented trough region play an important role for scattering far field, and primary edge diffracted field contributes mainly to reflection boundary direction.

A technique was developed to reduce ECG data efficiently within a controlled accuracy. The sampled and digitized data of the original waveform of an ECG is transformed in three major processes. They are the calculation of a beat-to-beat variation, a polygonal approximation and the calculation of the difference between consecutive node points. Then, an adaptive coding technique is applied to minimize redundancies in the data. It was demonstrated that the ECG waveform sampled in 200 Hz, 10 bit/sample, 5 µV/digit could be reduced with the bit reduction ratio of about 10% and within the reconstruction error of about 2.5%. A polygonal approximation method, called MSAPA, was newly developed as a modification of the well known method, SAPA. It was shown that the MSAPA gave better reduction efficiency and smaller reconstruction error than the SAPA, when it was applied to the beat-to-beat variation waveform. The importance of the low-pass filtering as a preprocessing for the polygonal approximation was confirmed in concrete examples. The efficiency of the proposed technique was compared with the cased in which the polygonal approximation was not used. Through these analyses, it was found that the redundancy elimination of the coding technique worked effectively in the proposed technique.

This paper describes an error-correcting parser (ec-parser) for context-free languages that is an extension of the Leiss's parser. Since the ec-parser uses precomputed informations and a pruning technique by lookahead, the ec-parser is always faster than the Lyon's parser. Several examples are shown.

In order to develop silicon ICs operating up to above 450, Integrated Injection Logic (IIL) was chosen. A new structure for IIL was designed through experimental and theoretical studies of pn junctions, transistors, and IIL at high temperatures. A 5-µm design rule was used. The new IIL was fabricated by a specially developed combined process of ion implantation and low temperature epitaxy. The IIL was fully operational from room temperature to 454, and the output amplitude of a nine-stage ring oscillator was about 30 mV at 454. The minimum delay time of the IIL was 22 nsec at 454. The minimum power-delay product was 11 pJ and was one-third of that for IILs fabricated by 10-µm rule at 50.

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.

A method for the compression of ECG data is presented. The method is based on the edit distance algorithm developed in the file comparison problems. The edit distance between two sequences of symbols is defined as the number of edit operations required to transform a sequence of symbols into the other. We adopt the edit distance algorithm to obtain a list of edit operations, called edit script, which transforms a reference pulse into a pulse selected from ECG data. If the decoder knows the same reference, it can reproduce the original pulse, only from the edit script. The amount of the edit script is expected to be smaller than that of the original pulse when the two pulses look alike and thereby we can reduce the amount of space to store the data. Applying the proposed scheme to the raw data of ECG, we have achieved a high compression about 14: 1 without losing the significant features of signals.

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.

We use the B spline function and apply the Oslo algorithm to minimize the number of control points in electrocardiogram (ECG) waveform compression under the limitation of evaluation indexes. This method is based on dynamic programming matching to transfer the control points of a reference ECG waveform to the succeeding ECG waveforms. This reduces the execution time for beat-to-beat processing. We also reduced the processing time at several compression stages. When the difference percent normalized root mean square difference is around 10, our method gives the highest compression ratio at a sampling frequency of 250 Hz.

This paper describes and analyzed several indices in assessing algorithms of data compression of electrocardiograms, such as the cross correlation (CC), the percent root mean square difference (PRD), and a new measure of standardized root mean square difference (SRD). Although these indices are helpful to objectively evaluate the algorithms, the visual examination of the reconstructed waveform is indispensable to decide the optimal compression ratio. This paper presents the clinical significance of selected waveforms which are prone to be distorted or neglected in the restored waveforms but are crucial for cardiologists to diagnose the patient. A database of electrocardiograms is also proposed for the comparative evaluation of compression algorithms.

This paper describes our recent developments of ASICs for automotive multiplexing and data communications to implement in-vehicle networks. With the advancement of automotive electronics, there are ever growing needs for in-vehicle networks. One need is associated with solving the problem of an increasing number of electrical signal wires that inevitably accompany the increasing applications of automotive electronics. Another kind of need is concerned with sharing vehicle control data among several electronic control units such as engine, brake, suspension, and steering electronic control units to achieve an integrated vehicle control system for the purpose of obtaining higher performances in vehicle dynamics. In order to reduce the number of signal wires and share the control data, in-vehicle networks based on multiplexing and data communications are required. In this paper, two original communication protocols are presented to respectively cover low- and highi-speed multiplexing and data communications that are two most needed communication speed areas in our present and future automobiles. ASICs for the presented communication protoclos were designed and fabricated, using 2 µm COMS process. They have the chip size of 3.2 mm2.7 mm with 5,000 transistors and 6.9 mm4.9 mm with 18,000 transistors respectively for low- and high-speed multiplexing and data communications. An elaborate bus driver/receiver ASIC required for high-speed multiplexing and data communications was also designed and fabricated, using 35 V DC bipolar process. As one of its distinctive features, it can greatly suppress radio frequency noise radiated from a communication bus. It has the chip size of 4.8 mm3.8 mm that contains 570 device elements. The features of the protocols are given in detail with the descriptions of the developed ASICs.

With the evolution of semiconductor technology, automotive electronics has made tremendous progress. The aim of automotive electronics is to improve the basic automotive functions of vehicles (running, turning, and stopping) from the standpoint of environmental protection, energy conservation, and transportation efficiency. This paper introduces the process of automotive electronics with an emphasis on major control systems such as engines and brakes. The role of ASICs in automotive control systems is also presented with actual examples of ASICs that are used in these systems.