Concerned is a spectral profile of electromagnetic (EM) emission from a signal line on a high-speed digital circuit. The authors have proposed and examined an a priori method to predict the peak frequencies on spectral profile of EM emission from printed circuit boards (PCBs). Profile of an EM spectrum is determined by the resonance of digital circuits. It is the purpose of this paper to investigate the parameters that determine the spectral profile of EM emission from a signal line on a PCS. In this paper, measurements and calculations of EM spectra were carried out for different load capacitances. EM emissions were measured with a small loop antenna at a 50mm from the surface of the PCB. Measured EM spectra had two peaks. Calculated EM spectra, which was based on transient current given by the analog simulator SPICE, had two peaks too. Results of calculations of EM spectra for different internal capacitances of an IC tell that lower peak frequency is determined by the resonance frequency of the resonant loop which is composed of an IC package and a decoupling capacitor. Comparison with measured EM spectra and calculated EM spectra for different load resistances tell that sharpness of the other peak depends on Q factor of a resonant loop which includes a signal line. Therefore the peak frequencies of EM emission spectrum can be predicted as two resonance frequencies of two resonant circuits.

For symmetric cryptosystems, their transformations should have nonlinear elements to be secure against various attacks. Several nonlinearity criteria have been defined and their properties have been made clear. This paper focuses on, among these criteria, the propagation criterion (PC) and the strict avalanche criterion (SAC), and makes a further investigation of them. It discusses the sets of Boolean functions satisflying the PC of higher degrees, the sets of those satisfying the SAC of higher orders and their relationships. We give a necessary and sufficient condition for an n-input Boolean function to satisfy the PC with respect to a set of all but one or two elements in {0,1}n{(0,...,0)}. From this condition, it follows that, for every even n 2, an n-input Boolean function satisfies the PC of degree n 1 if and only if it satisfies the PC of degree n. We also show a method that constructs, for any odd n 3, n-input Boolean functions that satisfy the PC with respect to a set of all but one elements in {0,1}n{(0,...,0)}. This method is a generalized version of a previous one. Concerned with the SAC of higher orders, it is shown that the previously proved upper bound of the nonlinear order of Boolean functions satisfying the criterion is tight. The relationships are discussed between the set of n-input Boolean functions satisfying the PC and the sets of those satisfying the SAC.

A new electrostatic wobble motor design and fabrication method were proposed, and micromotors were successfully fabricated and operated. The advantages are (1) thicker structural size, resulting in larger torque, (2) simple and safe fabrication process and (3) needle-shaped bearing to support the rotor. Needle-shaped bearing used here is expected to have lower friction comparing with the existing motor, since the load is smaller for this kind of bearing structure. Two major sources of the load, electrostatic force and capillary force, were considered to prove this tendency. Diamond-like Carbon (DLC) film was employed as a solid lubricant for its bearing. The friction of DLC and that of ilicon-dioxide were compared by experiment.

A composite noise generator (CNG) is proposed for simulating the actual non-Gaussian noise and its applications are mentioned. Basing upon the actual measured result (APD) of induced noise from electric contact discharge arc, the APD is approximated by partial linearlization and shown that it can be simulated by a combination of plural Gaussian noise sources. Applying the CNG, quasi-peak (Q-P) detector is investigated and shown that the Q-P detector response is different for non-Gaussian noise when its time domain parameter is different even if its original APD is the same. For digital transmission error due to non-Gaussian noise, and for TV picture stained by the non-Gaussian noise, the CNG is applied to evaluate their performances and quality. The results obtained show that the CNG can be used as a standard non-Gaussian generator for several immunity tests for information equipments.

The effects of Gaussian electromagnetic noise and non-Gaussian one on TV picture degradation are studied by using a composite noise generator which can control noise parameters. Three kinds of still pictures and four kinds of motion pictures are tested, and the picture degradation is subjectively evaluated with five-grade impairment scale. The tendency of the picture degradation against the every picture is almost the same. But MOS (Mean Opinion Score) between still picture and motion picture degradation is different in some measure when the power of burst noise is small.

In this study, after focussing on an energy (or intensity) scaled variable of acoustic systems, first, a new regression analysis method is theoretically proposed by introducing a multiplicative noise model suitable to the positively scaled stocastic system. Then, the effectiveness of the proposed method is confirmed experimentally by applying it to the actual acoustic data.

Let L{0,1}* be a language and let λL : {0,1}*{0,1} be the characteristic function of the language L, i.e., if x ∈ L, λL (x) = 1; otherwise,λL (x) = 0. In this paper, we consider an adaptive checker with a single program F (resp. noncommunicating multiple programs F1, F2,...) for λL that works even when an incorrect program F* (resp. incorrect noncommunicating multiple programs F*1,F*2,...) for λL adaptively behaves according to inputs previously provided to the program F* (resp. the programs F*1,F*2,...). We show that (1) for any language L, there exists an adaptive checker with a single program for λL iff L and respectively have competitive interactive proof systems; and (2) that for any language L, there exists an adaptive checker with noncommunicating multiple programs for λL iff L and respectively have function-restricted interactive proof systems. This implies that for any language L, adaptive chekers with noncommunicating multiple programs for λL are as powerful as static ones with a single program for λL.

Considering the trend towards adopting high efficiency picture coding schemes into digital broadcasting services, we investigate objective picture quality scales for evaluating digitally encoded still and moving pictures. First, the study on the objective picture quality scale for high definition still pictures coded by the JPEG scheme is summarized. This scale is derived from consideration of the following distortion factors; 1) weighted noise by the spatial frequency characteristics and masking effects of human vision, 2) block distortion, and 3) mosquito noise. Next, an objective picture quality scale for motion pictures of standard television coded by the hybrid DCT scheme is studied. In addition to the above distortion factors, the temporal frequency characteristics of vision are also considered. Furthermore, considering that all of these distortions vary over time in motion pictures, methods for determining a single objective picture quality value for this time varying distortion are examined. As a result, generally applicable objective picture quality scale is obtained that correlates extremely well with subjective picture quality scale for both still and motion pictures, irrespective of the contents of the pictures. Having an objective scale facilitates automated picture quality evaluation and control.

Plating is applied to protect contact surfaces of contact devices such as switch, relay and connector from contaminations of oxidization and sulfuration etc. Furthermore it is known that the contact resistance can be reduced when there exist plated layers on the contact surfaces which have enough thickness and low resistivity compared with substratum materials. In this paper, contact resistance between plated conductors are calculated using three dimensional finite element method. Similariry, current density distribution in a contact spot with various resistivity of plated layers are shown and relative conductance depends on the contact area fraction with thickness of plated layers are presented.

Composite materials of solid lubricants, such as graphite, MoS2, WS2, etc., and metals are being used as the sliding electrical contacts. However, few reports have so far been presented on the detailed characteristics of such composite materials. It is shown in this report that contact resistance and coefficient of friction of the sliding contact of the composite material of Cu-Nb system against Cu were higher than those of the sliding contact of the composite material of Cu-Sn system against Cu. It was, further, found that composite materials of Cu-Sn system were superior to those of Cu-Nb system being both contact resistances and coefficients of friction lowered. At the same time, it was found that performances of composite materials of Cu-Sn alloy base containing exclusively WS2 were superior to those containing both WS2 and MoS2. It was, therefore, suggested that proper samples suitable for the service conditions should be selected from the composite materials of Cu-Sn system which contain exclusively WS2 for the practical applications.

The electric or electronic circuits have many contact devices such as relay and switch. The contact between two nominally conducting flat surface has a lot of micro contact spots. The constriction resistance of the contact is known to determine the sum of the parallel resistance of the micro contacts and the interaction of them. The constriction resistance of two circular conducting spots was approximately formulated by Greenwood. This formulation shows that the interacted resistance of two circular spots is in inverse proportion to the distance between two conducting spots. It was known that this effect is introduced by the interaction between two conducting spots. However, the condition of interaction in the spots is not clear. Calculating the current density distribution in the spots is important to clarify the condition of interaction. The numerical analysis is very suitable to calculate the current density in the spots. In the fundamental case of the computation of the current density the boundary element method (BEM) is more efficient and accurate than that of the finite element method (FEM) because the boundary condition at the infinite is naturally satisfied and is not required a great number of the element in a wide space. In this paper the current density in the square spots is computed by the BEM. As the distance between two conducting spots becomes small, the current density in the two spots decreases. It becomes clear that the constriction resistance of conducting spots is increased by this effect. The decrease of current density by interaction is not uniformly, that at the near location to the opposite spot is larger than that at the far location in the same spot. In this paper the constriction resistance of two conducting spots is also considered. It was known that the constriction resistance of one conducting spot is not influenced by the form of spot very much. However, that of two conducting spots is not clear. The constriction resistance of two square spots is also computed by the BEM. The computed values of the constriction resistance of two square spots are compared with that of two circular spots by Greenwood's formulation and other results. As the result, it is clear that they have the considerable discrepancy. However, the trend of the variations is almost agree each other.

We developed a simple, practical, adaptive data compression algorithm of the LZ78 class. According to the Lempel-Ziv greedy parsing, a string boundary is not related to the statistical history modeled by finite-state sources. We have already reported an algorithm classifying data into subdictionaries (CSD), which uses multiple subdictionaries and conditions the current string by using the previous one to obtain a higher compression ratio. In this paper, we present a practical implementation of this method suitable for any kinds of data, and show that CSD is more efficient than the LZC which is the method used by the program compress available on UNIX systems. The CSD compression performance was about 10% better than that of LZC with the practical dictionary size, an 8k-entry dictionary when the test data was from the Calgary Compression Corpus. With hashing, the CSD processing speed became as fast as that of LZC, although the CSD algorithm was more complicated than LZC.

This paper propeses a new motion compensation (MC) technique which reduces blurring called drift in moving pictures down-scaled with layered coding system. Encoder of the system compresses large amounts of digital video data in the same way of MPEG (Moving Picture Experts Group) algorithm. Decoder, on the other hand, expands a part of the compressed data and reconstructs down scaled pictures. The purpose of this paper is to reduce blurring which is observed in the reconstructed pictures. In this paper, cause of the blurring is analyzed and the method is introduced as a solution to the problem. The new method is implemented by a little modification of motion compensation (MC) of the decoder, namely increasing the number of tap of interpolation fillters of the MC. Compressing moving pictures, its effectiveness is also confirmed by means of not only subjective test but also signal to noise ratio.

Wide-band, low-ripple underwater transducers with high-power acoustic radiation capability have been designed on the basis of multiple-mode filter synthesis theory. They are composed of triple acoustic matching plates and double backing plates with optimized specific acoustic impedances,besides piezoelectric ceramic elements. One of the backing plates employs a Fe damping-alloy to suppress unwanted response peaks in the frequency range above the passband region. Two 33 array transducers were fabricated, each with a center frequency of 200 kHz, one as a transmitter and the other as a receiver. The two transducers show high-sensitivity, low-ripple and wide-band transmitting and receiving responses. Then, the transducers were applied in a color video picture digital transmission system.Clear color video pictures, composed of 256240 pixels, were successfully received within one second.

In this paper, radio propagation in the medium-scale building is investigated at 2.5GHz band. In order to predict the propagation loss in any place, four major modes of propagation are considered: low-loss in line-of-sight (LOS) wave, corridor guided wave, direct transmission wave through obstructions, and the reentered wave. Based on the measured results of attenuation characteristics, the macroscopic parameters for the above mentioned modes of wave propagation are determined. Using these parameters, signal strengths are predicted with average standard deviation of 4.5dB. The fading characteristics are studied by measuring the Rician parameter and the correlation coefficient for 2-branch diversity antennas separated by 50cm. The Rician parameters are 2 in case of the LOS propagation, and 1 in case of the no LOS propagation. The two branch correlation coefficients are less than 0.5 within coverage of 80-95% in almost all the locations.

Antenna selection diversity is an effective method to achieve both better transmission performance and compact circuit implementation in TDMA portable radio communications. However, diversity performance in fast fading environments is insufficient. This paper proposes a novel predictive antenna selection diversity scheme, PASD, which improves the diversity performance for higher fading rates. In PASD, received signal power for the assigned data slot is predicted from previously measured data. Thus, selection errors due to the receiving power changes caused by fast Rayleigh fading can be effectively avoided. An experimental result for a 3-ch TDMA system with a frame duration of 20ms shows that the diversity gain was increased by 1.3dB over the conventional method for a fading rate of 40Hz. PASD is also shown to have improved diversity performance against cochannel interference.

This paper presents a new method for resolving lexical (word sense) ambiguities inherent in natural language sentences. The Sentence Analyzer (SENA) was developed to resolve such ambiguities by using constraints and example-based preferences. The ambiguities are packed into a single dependency structure, and grammatical and lexical constraints are applied to it in order to reduce the degree of ambiguity. The application of constraints is realized by a very effective constraint-satisfaction technique. Remaining ambiguities are resolved by the use of preferences calculated from an example-base, which is a set of fully parsed word-to-word dependencies acquired semi-automatically from on-line dictionaries.

In this paper, we investigate the knowledge complexity of interactive proof systems and show that (1) under the blackbox simulation, if a language L has a bounded move public coin interactive proof system with polynomially bounded knowledge complexity in the hint sense, then the language L itself has a one move interactive proof system; and (2) under the blackbox simulation, if a language L has a three move private coin interactive proof system with polynomially bounded knowledge complexity in the hint sense, then the language L itself has a one move interactive proof system. These results imply that as long as the blackbox simulation is concerned, any language L AM＼MA is not allowed to have a bounded move public coin (or three move private coin) interactive proof system with polynomially bounded knowledge complexity in the hint sense unless AM = AM. In addition, we present a definite distinction between knowledge complexity in the hint sense and in the strict oracle sense, i.e., any language in AM (resp. IP) has a two (resp. unbounded) move public coin interactive proof system with polynomially bounded knowledge complexity in the strict oracle sense.

Student contradictions are the essentials of concepts and knowledge acquisition processes of a student, in the course of tutoring. This paper presents a new perspective to represent student contradictions and a student modeling architecture to capture them. The formulation of a student modeling mechanism enables flexible decision making by using information obtained from students. A nonmonotonic and inductive student model inference system HSMIS has been developed and formulated to cope with modeling contradictions, which basically embodies advanced representation power, sufficiently high adaptability and generality. The HSMIS is evaluated and compared with other representative systems in order to demonstrate its effectiveness.

We analyze frame rates in low bit rate video coding and show that an optimal frame rate can be theoretically obtained. In low bit rate video coding the frame rate is usually forced to be decreased for reducing the total amount of coded information. The choice of frame rate, however, has a great effect on the picture quality in a trade-off relation between coded picture quality and motion smoothness. It is known from experience that in order to achieve an optimum balance between these two factors, a frame rate has to be selected which is appropriate for the coding scheme, property of the video sequences and coding bit rate. A theoretical analysis, however, on the existence of an optimal frame rate and how the optimal frame rate would be expressed has not been performed. In this paper, coding distortion measured by mean square error is analyzed by using video signal models such as a rate-distortion function for coded frames and inter-frame correlation coefficients for non-coded frames. Overall picture quality taking account of coded picture quality and motion smoothness simultaneously is expressed as a function of frame rate. This analysis shows that the optimum frame rate can be uniquely specified. The maximum frame rate is optimal when the coding bit rate is higher than a certain value for a given video scene, while a frame rate less than the maximum is optimal otherwise. The result of the theoretical analysis is compared with the results of computer simulation. In addition, the relation between this analysis and a subjective evaluation is described. From both comparisons this theoretical analysis can be justified as an effective scheme to indicate the optimal frame rate, and it shows the possibility of improving picture quality by selecting frame rate adaptively.