A rectenna element applicable to Stratosphere Radio Relay System was proposed and a fundamental microwave power transmission experiment was carried out at 2.45GHz using a rectenna array manufactured based on the proposal. The rectenna element consists of a circular microstrip patch and a rectifying circuit of novel balanced-type design. The circuit allows to mount a rectifier and circuit components just on one side of a substrate without through holes, and hence it must be easy to manufacture a rectenna even having a large aperture. It was verified by a preliminary experiment that the rectifying circuit can provide more than 1 W of DC output power using 8 Shottky diodes as a rectifier with microwave-DC conversion efficiency of 67%. Then, DC output power of 4W was obtained from the 4-element rectenna array in the microwave power transmission experiment carried out in a radio anechoic chamber. The data showed a feasibility of practical application of the microwave power transmission technique.

This paper proposed a new algorithm of data compression for ambulatory ECG, where no distortion was included in the reconstructed signal, templates were constructed selectively from detected beats, and categorized ECG morphologies (templates) could be displayed in decoding the compressed data. This algorithm consisted of subtracting a best-fit template from the detected beat with an aid of multi-template matching, first differencing of the resulting residuals and modified Huffman coding. This algorithm was evaluated by applying it to ECG signals of the American Heart Association (AHA) data base in terms of bit rates. Following features were indicated. (1) Decompressed signal coincided completely with the original sampled ECG data. (2) Bit rate was approximately 800 bps at the appropriate threshold 50-60 units (1 unit2.4µVolt) for the template matching. This bit rate was almost the same as that of the direct compression (encoding the first differenced signal of original signal). (3) The decompressed templates could make it easy to classify the templates into the normal and abnormal beats; this could be executed without fully decompressing the ECG signal.

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.

Text-to-speech synthesis (TTS) is currently one of the most important media conversion techniques. In this paper, we describe a Japanese TTS card developed for constructing a personal-computer-based multimedia platform, and a TTS software package developed for a workstation-based multimedia platform. Some applications of this hardware and software are also discussed. The TTS consists of a linguistic processing stage for converting text into phonetic and prosodic information, and a speech processing stage for producing speech from the phonetic and prosodic symbols. The linguistic processing stage uses morphological analysis, rewriting rules for accent movement and pause insertion, and other techniques to impart correct accentuation and a natural-sounding intonation to the synthesized speech. The speech processing stage employs the cepstrum method with consonant-vowel (CV) syllables as the synthesis unit to achieve clear and smooth synthesized speech. All of the processing for converting Japanese text (consisting of mixed Japanese Kanji and Kana characters) to synthesized speech is done internally on the TTS card. This allows the card to be used widely in various applications, including electronic mail and telephone service systems without placing any processing burden on the personal computer. The TTS software was used for an E-mail reading tool on a workstation.

A soft-decision decoding algorithm for binary linear block codes is proposed. This algorithm seeks to minimize the block error probability. With careful examinations of the first hard-decision decoded results, the candidate codewords are efficiently searched for. Thus, we can reduce the decoding complexity (the number of hard-decision decodings) and lower the block error probability. Computer simulation results are presented for the (23, 12) Golay code. They show that the decoding complexity is considerably reduced and the block error probability is close to that of the maximum likelihood decoder.

A two-dimensional photoemission analysis of hot-carrier effects in LOCOS- and trench-isolated CMOS devices with channel width ranging from 160 µm to 0.2 µm is described. Photoemission-intensity profiles can be measured in spatial resolution of 0.1 µm. Different photoemission characteristics are observed in n-MOSFETs depending on isolation technology; M-shaped photoemission-intensity profiles are observed as gate voltage becomes higher in trench-isolated ones, but scarcely measured in LOCOS-isolated ones. As for p-MOSFETs, similar characteristics are observed independent on isolation technology and slightly M-shaped profiles are observed at higher gate voltages. The recession of 0.1-0.2 µm in photoemission area from the gate electrode edge due to gate bias dependence of the pinch-off points of n--LDD drain is observed when gate voltage increases from 1 V to 6 V. Meanwhile the recession of the pinch-off points in p-MOSFETs is less than 0.1 µm even when gate voltage increases from 2 V to 8 V. A qualitative explanation for the experimental results is given for four kinds of MOSFETs in comparing each device structure near the isolation edge.

Computing devices have reached data frequencies of 100 MHz, and have created a need for small-amplitude impedance-matched buses. We simulated signal transmission characteristics of two basic driver circuits, push-pull and open-drain,for a synchronous DRAM I/O bus. The push-pull driver caused less signal distortion with parasitic inductance and capacitance of packages, and thus has higher frequency limits than the open-drain GTL type. We describe a bus system using push-pull drivers which operates at over 125 MHz. The bus line is 70 cm with 8 I/O loads distributed along the line, each having 25 nH7pF parasitic inductance and capacitance.

Until now, in a communication system which deals with multiple processes, system behavior has been described by a fixed number of processes. The state reachability problem for specified processes was generally deliberated within a pre-defined number of processes, and was analyzed by essentially searching for all possible behaviors. However, in a system whose number of processes is arbitrary, a given state which is not reachable in some situations which consists of a small number of processes might be reachable in another situation which consists of a larger number of processes. This article discusses the above problem, assuming that the behavior of a system is described by an arbitrary number of processes. After discussing the relationship between our model and the Petri net model, we clarify the properties between the set of reachable states and the number of processes involved in the system, and show an algorithm to obtain a sufficient number of processes for resolving the reachability problem.

We propose an advanced hyper parallel testing method which improves the line-mode test method by adding data inversion registers which we call the Advanced Line-mode Test (ALT). This testing method has the same testing capability as the conventional bit-by-bit and multi-bit test method (MBT), because it enables the application of a high sensitive and practical test patterns under the hyper parallel condition. The testing time for fixed data patterns are reduced by 1/1900 (all-0/1, checker board, and etc.). Moreover, the ALT can be applicable to the continuous patterns (march, walking, and etc.). The ALT improved from the line-mode test with registers and comparators (LTR) is able to applicable to the most test patterns and to reduce the testing time remarkably, and is suitable for the ULSI memories.

This paper describes automatic generation of speech synthesis rules which predict a stress level for each bunsetsu in long noun phrases. The rules are inductively inferred from a lot of speech data by using two kinds of tree-based methods, the conventional decision tree and the SBR-tree methods. The rule sets automatically generated by two methods have almost the same performance and decrease the prediction error to about 14 Hz from 23 Hz of the accent component value. The rate of the correct reproduction of the change for adjacent bunsetsu pairs is also used as a measure for evaluating the generated rule sets and they correctly reproduce the change of about 80%. The effectiveness of the rule sets is verified through the listening test. And, with regard to the comprehensiveness of the generated rules, the rules by the SBR-tree methods are very compact and easy to human experts to interpret and matches the former studies.

This paper presents a high-density multiple-valued content-addressable memory (MVCAM) based on a floating-gate MOS device. In the proposed CAM, a basic operation performed in each cell is a threshold function that is a kind of inverter whose threshold value is programmable. Various multiple-valued operations for data retrieval can be easily performed using threshold functions. Moreover, each cell circuit in the MVCAM can be implemented using only a single floating-gate MOS transistor. As a result, the cell area of the four-valued CAM are reduced to 37% in comparison with that of the conventional dynamic CAM cell.

This paper presents a method for verifying safety property of a communication protocol modeled as two extended communicating finite-state machines with two unbounded FIFO channels connecting them. In this method, four types of atomic formulae specifying a condition on a machine and a condition on a sequence of messages in a channel are introduced. A human verifier describes a logical formula which expresses conditions expected to be satisfied by all reachable global states, and a verification system proves that the formula is indeed satisfied by such states (i.e. the formula is an invariant) by induction. If the invariant is never satisfied in any unsafe state, it can be concluded that the protocol it safe. To show the effectiveness of this method, a sample protocol extracted from the data transfer phase of the OSI session protocol was verified by using the verification system.

The authors developed a portable Japanese text-to-speech system using a pocket-sized formant speech synthesizer. It consists of a linguistic processor and an acoustic processor. The linguistic processor runs on an MS-DOS personal computer and has functions to determine readings and prosodic information for input sentences written in kana-kanji-mixed style. New techniques, such as minimization of a cost function for phrases, rare-compound flag, semantic information, information of reading selection and restriction by associated particles, are used to increase the accuracy of readings and accent positions. The accuracy of determining readings and accent positions is 98.6% for sentences in newspaper articles. It is possible to use the linguistic processor through an interface library which has also been developed by the authors. Consequently, it has become possible not only to convert whole texts stored in text files but also to convert parts of sentences sent by the interface library sequentially, and the readings and prosodic information are optimized for the whole sentence at one time. The acoustic processor is custom-made hardware, and it has adopted new techniques, for the improvement of rules for vowel devoicing, control of phoneme durations, control of the phrase components of voice fundamental frequency and the construction of the acoustic parameter database. Due to the above-mentioned modifications, the naturalness of synthetic speech generated by a Klatt-type formant speech synthesizer was improved. On a naturalness test it was rated 3.61 on a scale of 5 points from 0 to 4.

A text-to-speech conversion system for Japanese has been developed for the purpose of producing high-quality speech output. This system consists of four processing stages: 1) linguistic processing, 2) phonological processing, 3) control parameter generation, and 4) speech waveform generation. Although the processing at the first stage is restricted to the texts on general weather conditions, the other three stages can also cope with texts of news and narrations on other topics. Since the prosodic features of speech are largely related to the linguistic information, such as word accent, syntactic structure and discourse structure, linguistic processing of a wider range than ever, at least a sentence, is indispensable to obtain good quality speech with respect to the prosody. From this point of view, input text was restricted to the weather forecast sentences and a method for linguistic processing was developed to conduct morpheme, syntactic and semantic analyses simultaneously. A quantitative model for generating fundamental frequency contours was adopted to make a good reflection of the linguistic information on the prosody of synthetic speech. A set of prosodic rules was constructed to generate prosodic symbols representing prosodic structures of the text from the linguistic information obtained at the first stage. A new speech synthesizer based on the terminal analog method was also developed to improve the segmental quality of synthetic speech. It consists of four paths of cascade connection of pole/zero filters and three waveform generators. The four paths are respectively used for the synthesis of vowels and vowel-like sounds, nasal murmur and buzz bar, friction, and plosion, while the three generators produce voicing source waveform approximated by polynomials, white Gaussian noise source for fricatives and impulse source for plosives. The validity of the approach above has been confirmed by the listening tests using speech synthesized by the developed system. Improvements both in the quality of prosodic features and in the quality of segmental features were realized for the synthetic speech.

This paper presents a collision warning system that uses laser radar to measure the distance to a preceding vehicle and issues an audible warning to alert the driver if a safe headway is not maintained. The laser radar system is of the cooperative type in that it detects light reflected from a reflex reflector attached at the rear of other vehicles. With a 10-watt pulsed laser, a maximum detection range of over 100m is obtained. The construction and operation of the collision warning system are described along with the configuration of the optical system used in the laser radar head and the results of detection performance evaluations.

Scattering characteristics of a stratified chiral slab, which is composed of dielectric chiral layers of different material properties and thicknesses, are extensively explored. Design considerations for optical filters are also presented for both the cases of normal and oblique incidence. In the analysis, the incident field is assumed to be a plane monochromatic wave of any arbitrary polarization. The transmitted and reflected electric fields are obtained by noting the fact that the electric field inside a chiral medium is expressed as a sum of the left- and right-circularly polarized plane waves of different phase velocities. Then one can describe the power densities and the Stokes parameters of the transmitted and reflected waves in terms of their field components. As is well known,the Stokes parameters characterize every possible state of polarization of a plane wave. Numerical examples are presented to show the effects of chirality on polarization conversion properties of the stratified chiral slab. The cross- and co-polarized powers and the Stokes parameters of the transmitted and reflected waves are computed for the incident wave of perpendicular polarization. The numerical results demonstrate novel depolarization properties of the slab with application to the design of efficient filters active at the optical region. It is seen from the results that the stratified chiral slab acts as a polarization-conversion transmission filter that passes only a cross-polarized component of the transmitted wave at some frequency band. Furthermore, the slab may be utilized as an antireflection filter for both the cross- and co-po1arized components of the reflected wave at the band region.

This paper describes a noise resistant algorithm for recovering the three-dimensional motion of a rigid object from optical flow. First, it is shown that in the absence of noise three-demensional motion can be obtained exactly by a linear algorithm except in the special case in which the surface of the object is on a general quadratic surface passing through the viewpoint, and the normal vector of the surface at the viewpoint is perpendicular to the translation velocity vector. In the presence of noise, an evaluation function is introduced based on the least squares method. It is shown, however, that the solution which minimizes the evaluation function is not always optimal due to statistical bias. To deal with this problem, a method to eliminate the statistical bias in the evaluation function is proposed for zero mean white noise. Once the statistical bias is eliminated, the solution of the linear algorithm coincides with the correct solution by means of expectation. In this linear algorithm, only the eigenvector corresponding to the zero eigenvalue of a 33 matrix is necessary to find the translational velocity. Once the translational velocity is obtained, the rotational velocity can be computed directly. This method is also shown to be noise resistant by computer simulation.

Recently, there has been a lot of research on solving combinatorial problems using Binary Decision Diagrams (BDDs), which are very efficient representations of Boolean functions. We have already developed a Boolean Expression Manipulator, which calculates and reduces Boolean expressions quickly based on BDD techniques. This greatly aids our works on developing VLSI CAD systems and solving combinatorial problems. Any combinatorial problem can be described in Boolean expressions; however, arithmetic operations, such as addition, subraction, multiplication, equality and inequality, are also used for describing many practical problems. Arithmetic operations provide simple descriptions of problems in many cases. In this paper, we present an arithmetic Boolean expression manipulator (BEM-), based on BDD techniques. BEM- calculates Boolean expressions containing arithmetic operations and then displays the results in various formats. It can solve problems represented by a set of equalities and inequalities, which are dealt with using 0-1 linear programming. We show the efficient data structure based on BDD representation, algorihms for manipulating Boolean expressions with arithmetic operations, and good formats for displaying the results. Finally we present the specification of BEM- and an example of application to the 8-Queens problem. BEM- is customizable to various applicationa. It has good computation performance in terms of the total time for programming and execution. We expect BEM- to be a helpful tool in research and development on digital systems.

This paper discusses methods and numerical simulations of one and two dimensional profilings for an arbitrary convex conducting target using the electromagnetic backscattering. The inversions for profile reconstructions are based upon the modified extended physical optics method (EPO). The modified EPO method assumes the modified physical optics current properly over the entire surface of conducting scatterers. First, the cross sectional area along a line of sight is reconstructed by performing iteratively the Fourier transform of the backscattering field in the frequency domain. Second, the two dimensional profile is reconstructed by synthesizing the above one dimensional results for several incident angles. Numerical simulation results of the target profiling are shown for spheroids and cone-spheroid.

The character binarization method MTC is developed for enhancing the recognition of characters in general outdoor images. Such recognition is traditionally difficult because of the influence of illumination changes, especially strong shadow, and also changes in character, such as apparent character sizes. One way to overcome such difficulties is to restrict objects to be processed by using strong hypotheses, such as type of object, object orientation and distance. Several systems for automatic license plate reading are being developed using such strong hypotheses. However. their strong assumptions limit their applications and complicate the extension of the systems. The MTC method assumes the most reasonable hypotheses possible for characters: they occupy plane areas, consist of narrow lines, and external shadow is considerably larger than character lines. The first step is to eliminate the effect of local brightness changes by enhancing feature including characters. This is achieved by applying mathematical morphology by using a logarithmic function. The enhanced gray-scale image is then binarized. Accurate binarization is achieved because local thresholds are determined from the edges detected in the image. The MTC method yields stable binary results under illumination changes, and, consequently, ensures high character reading rates. This is confirmed with a large number of images collected under a wide variety of weather conditions. It is also shown experimentally that MTC permits stable recognition rate even if the characters vary in size.