The discrete time analysis of logic circuits is usually more efficient than the continuous time analysis, but the preciseness of the discrete time analysis is not guaranteed. The paper shows a method to decide a unit time for a logic circuit under which the analysis result is the same as the result based on the continuous time. The delay time of an element is specified with an interval between the minimum and maximum delay times, and we assume an analysis method which enumerates all possible delay cases under the deisrete time. Our main theorem is as follows: refine the unit time by a factor of 1/2, and if the analysis result with a unit time u and that with a unit time u/2 are the same, then u is the expected unit time.

The performance of ASIPs (Application Specific Integrated Processors) is heavily affected by the design of their instruction set architecture. In order to maximize the performance of ASIP, it is essential to design an architecture that has an optimum instruction set. This paper descibes a new method that automates the design of optimum instruction set of ASIP. This method solves the Instruction set implementation Method Selection Problem(IMSP). IMSP is to be solved in the instruction set architecture design. Frse, the IMSP is formalized as an integer programming problem, which is to maximize the perfomance of the CPU under the constraints of chip area and power consumption. Then, a branch-and-bound algorithm to solve IMSP is described. According to the experimental results, the proposed algorithm is quite effective and efficient in solving the IMSP. The presented method automates a complex part of the ASIP chip design and is also a good design tool that enables designer to predict the performance of their design before completion.

This article discusses on PDM (Petri net based Development Methodology) which integrates approaches, modeling methods, design methods and analysis methods in a coherent manner. Although various development techniques based on Petri nets have demonstrated advantages over conventional techniques, those techniques are rather ad hoc and lack an overall picture on entire development process. PDM anticipates to provide a refernce process model to develop distributed systems with various Petri net based development methods. Behavioral properties of distrbuted systems can be an appropriate application domain of PDM.

In this paper, we will clarify the problem of consecutively lost customer due to buffer overflow in an IPP, M/M/l/K queueing system including an M1, M2/M/l/K queueuing system as a special case. We define a length of a consecutive loss as the number of customers consecutively lost due to buffer overflow. And, we obtain individual distributions of the lengths of consecutive losses for the IPP- and Markov-sources. From analytical and numerical results, it is shown that either they are geometrical or they can be approximated by a geometric distribution. Also, from numerical examples, we show some properties of the length of consecutive customer loss.

In this paper, we show that Petri nets can be applied practically to design and analysis of concurrent, parallel and embedded mode systems such as a lift system that is familiar to our daily life. Modeling behavioral characteristics of the lift, we extend a standard Petri net by constant timed transition, faultable transition, stochastic transition and condition transition concepts. Likewise, we prsesnt some results of design and analysis of the system. This method can be applied to design and analysis of another concurrent systems.

When orignal signals are contaminated by both additive and signal-dependent noise components, the test statistics of locally optimum detector are obtained for detection of weak composite signals based on the generalized Neyman-Pearson lemma. In order to consider the non-additive noise as well as purely-additive noise, a generalized observation model is used in this paper. The locally optimum detector test statisics are derived for all different cases according to the relative strengths of the known signal, random signal, and signal-dependent noise components. Schematic diagrams of the structures of the locally optimum detector are also included. The finite sample-size performance characteristics of the locally optimum detector are compared with those of other common detectors.

High speed simulation of neural networks can be achieved through parallel implementations capable of exploiting their massive inherent parallelism. In this paper, we show how this inherent parallelism can be effectively exploited on parallel data-driven systems. By using these systems, the asynchronous parallelism of neural networks can be naturally specified by the functional data-driven programs, and maximally exploited by pipelined and scalable data-driven processors. We shall demonstrate the suitability of data-driven systems for the parallel simulation of neural networks through a parallel implementation of the widely used back propagation networks. The implementation is based on the exploitation of the network and training set parallelisms inherent in these networks, and is evaluated using an image data compression network.

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.

A fully focused Synthetic Aperture Radar (SAR) image can be obtained only if the raw data processing procedure takes into account the space-variance of the SAR system transfer function. This paper presents a nonconventional Fast Fourier Transform (FFT) algorithm which allows an efficient compensation of the space-variant effect. It is specially designed for the SAR data of the Japanese Earth Resources Satellite (JERS-1) but can be extended to different cases.

A multi-beam airborne pulsed-Doppler radar (MBR) system is presented and its clutter rejection performance compared with conventional phased array radar (PAR)'s by PRF tuning is discussed. The pulsed-Doppler radar equations taking account of the multi-beam operation are introduced and some kinds of computer simulations for seeking the conditions to get maximum signal to clutter ratio are carried out. As a results of this, it is cleared that same order of signal to clutter ratio improvement gotten in high PRF operation by conventional PAR can be realized at lower PRF operation by MBR on clutter free area, and higher clutter rejection effect, which is proportional to beam numbers, is obtained under affection of both of mainlobe and sidelobe clutters with order of beam numbers. This also means observable numbers of range bin are increased in MBR operation.

We propose a third-order low-pass notch filter realized by a single operational amplifier and a minimum number of equal-valued capacitors. As a design example we realize a Chebyshev filter with a ripple of 0.5 dB and it is shown that the experiment result is very good.

This letter reports in detail on the temperature-dependent signal gain characteristics of Er3+-doped optical fiber amplifiers at signal wavelengths of 1.536µm and 1.552µm. The amplifiers were pumped at 0.825µm in a temperature range of 40 to 200. The signal gain for optimum length at both wavelengths stops increasing and begins to decrease at about 80. In the temperature region below 80, both signal gains increase with fiber temperature for fibers of optimum length or less. A temperature independent length aroud the optimum length is observed from 80 to 200 for both signal wavelengths. Theoretically, the temperature dependence of the signal gain characteristics rerults from the changes in fluorescence, absorption, GSA and ESA cross sections.

This paper describes a new algorithm for finding the contours of a moving object in an image sequence. A distinctive feature of this algorithm is its complete bottom-up strategy from image data to a consistent contour description. In our algorithm, an input image sequence is immediately converted to a complete set of quasi logical spatio-temporal measures on each pixel, which provide constraints on varying brightness. Then, candidate regions in which to localize the contour are bounded based on consistent grouping among neighboring measures. This reduces drastically the ambiguity of contour location. Finally, Some mid-level constraints on spatial and temporal smoothness of moving boundaries are invoked, and they are combined with these low-level measures in the candidate regions. This is performed efficiently by the regularization over the restricted trajectory of the moving boundary in the candidate regions. Since any quantity is dimensionless, the results are not affected by varying conditions of camera and objects. We examine the efficiency of this algorithm through several experiments on real NTSC motion pictures with dynamic background and natulal textures.

Many simulators in several fields use the finite difference method and they must solve the large sparse linear equations related. Particularly, if we use the direct solution method because of the convergency problem, it is necessary to adopt a method that can reduce the CPU time greatly. The Multi-Step Diakoptics (MSD) method is proposed as a parallel computation method with a direct solution which is based on Diakoptics, that is, a tearing-based parallel computation method for the sparse linear equations. We have applied the MSD algorithm for one, two and three dimensional finite difference methods. We require a parallel schedule that automatically partitions the desired object's region for study, assigns the processor elements to the partitioned regions according to the MSD method, and controls communications among the processor elements. This paper describes a parallel scheduling that was extended from a one dimensional case to a three dimensional case for the MSD method, and the evaluation of the algorithm using a massively parallel computer with distribuled memory(AP1000).

In the ISAR (Inverse Synthetic Aperture Radar), when a target is to be recognized by use of the radar image produced from the radar echoes, it is important first to estimate the scale of the target. To estimate the scale, the rotating motion of the target must be estimated. This paper describes a method for estimating the scale of the target from the information on the radar image by converting the target figure into a simple model and estimating the rotating motion of the target.

Full scan design of sequential circuits results in greatly reducing the cost of their test generation. However, it introduces the extra expense of many test clocks to control and observe the values of flip-flops because of the need to shift values for the flip-flops into the scan panh. In this paper we propose a new method of generating compact test sequences for scan-based sequential circuits on the assumption that the number of shift clocks is allowed to vary for each test vector. The method is based on Boolean function manipulation using a shared binary decision diagram (SBDD). Although the test generation algorithm is basically for general sequential circuits, the computational cost is much lower for scan-based sequential circuits than for non-scanbased sequential circuits because the length of a test sequence for each fault is limited. Experimental results show that, for all the tested circuits, test sequences generated by the method require much smaller number of test clocks than compact or minimum test sets for combinational logic part of scan-based sequential circuits. The reduction rate was 48% on the average in the experiments.

This paper proposes a new method for automatic improvement in image quality through adjusting the image sharpness. This method does not need prior knowledge about image blur. To improve image quality, the sharpness must be adjusted to an optimal value. This paper shows a new method to evaluate sharpness without MTF. It is considered that the human visual system judges image sharpness mainly based upon edge area features. Therefore, attention is paid to the high spatial frequency components in the edge area. The value is defined by the average intensity of the high spatial fequency components in the edge area. This is called the image edge sharpness" value. Using several images, edge sharpness values are compared with experimental results for subjective sharpness. According to the experiments, the calculated edge sharpness values show a good linear relation with subjective sharpness. Subjective image sharpness does not have a monotonic relation with subjective image quality. If the edge sharpness value is in a particular range, the image quality is judged to be good. According to the subjective experiments, an optimal edge sharpness value for image quality was obtained. This paper also shows an algorithm to alter an image into one which has another edge sharpness value. By altering the image, which achieves optimal edge sharpness using this algorithm, image sharpness can be optimally adjusted automatically. This new image improving method was applied to several images obtained by scanning photographs. The experimental results were quite good.

This paper describes a new single-unit underground radar for detecting underground buried pipes. The pipe depth can be calculated from the hyperbolic shape in the cross-sectional image of radar echoes. The edge contour of the image is extracted, and the buried depth is judged from the similarity between the extracted hyperbolic curve and the theoretical curve. A suitable amplification rate is estimated by choosing the best image from numerous cross-sectional images formed during one antenna movement repeated at different amplification rates. The best image has few pixels corresponding to weak and saturated signals. The new radar is very compact, so it can be operated by one person. Objects buried up to 2.0m deep can be detected.

An efficient algorithm is presented for finding all solutions of piecewise-linear resistive circuits. In this algorithm, a simple sign test is performed to eliminate many linear regions that do not contain a solution. Therefore, the number of simultaneous linear equations to be solved is substantially decreased. This test, in its original form, requires O(Ln2) additions and comparisons in the worst case, where n is the number of variables and L is the number of linear regions. In this paper, an effective technique is proposed that reduces the computational complexity of the sign test to O(Ln). Some numerical examples are given, and it is shown that all solutions can be computed very efficiently. The proposed algorithm is simple and can be easily programmed by using recursive functions.

The fast and highly reliable method reported here uses two techniques to detect all types of defects, such as unsoldered leads, solder bridges, and misalignes leads in the minute solder joints of high density mounted devices. One technique uses external force applied by an air jet that vibrates or shifts unsoldered leads. The vibration and shift is detected as a change in the speckle pattern produced by laser illumination of the solder joints. The other technique uses fluorescence generated by short-wavelength laser illumination. The fluorescence from a printed circuit board produces a silhouette of the solder joint and this image is processed to detect defects. Experimental results show that this inspection method detects all kinds of defects accurately and with a very low false alarm rate.