A method for constructing a compact non-blocking, large matrix-size, optomechanical switch is proposed. It can be switched arbitrarily by disconnecting and reconnecting ferrules on the matrix board. A 250500, 25-mm-ferrule-pitch, 800W855D945H (mm) switch is fabricated. Although the space above the board is densely packed with many ferrule-terminated-fibers, because of the way in which they are arranged and the control of their length, there is no discernible excess loss due to fiber bending.

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.

This paper proposes a new scheme for concatenative speech synthesis to improve the speech segment selection procedure. The proposed scheme selects a segment sequence for concatenation by minimizing acoustic distortions between the selected segment and the desired spectrum for the target without the use of heuristics. Four types of distortion, a) the spectral prototypicality of a segment, b) the spectral difference between the source and target contexts, c) the degradation resulting from concatenation of phonemes, and d) the acoustic discontinuity between the concatenated segments, are formulated as acoustic quantities, and used as measures for minimization. A search method for selecting segments from a large speech database is also descrided. In this method, a three-step optimization using dynamic programming is used to minimize the four types of distortion. A perceptual test shows that this proposed segment selection method with minimum distortion criteria produces high quality synthesized speech, and that contextual spectral difference and acoustic discontinuity at the segment boundary are important measures for improving the quality.

The performance of various ARQ protocols has recently been analyzed for multidestination environments. In all previous work, the round-trip delays between the transmitter and each of the receivers are assumed (or forced) to be equal to the maximum one, to simplify the analysis and/or the operation. This assumption obviously will sacrifice the system performance. In this paper, we evaluate the throughput efficiencies of three multidestination GBN ARQ protocols under unequal round-trip delays. In the investigated protocols, multiple copies of each data block are (re)transmitted contiguously to the receivers. Tight lower bounds are obtained for the throughput efficiencies of the schemes in which each data block is transmitted with the optimum number of copies. Results show that assuming all the round-trip delays to be equal to the maximum one may sacrifice the performance significantly. We also compare the performances of the three investigated protocols. In general, the performance becomes better as the transmitter utilizes more of the outcomes of previous transmission attempts.

A stored channel simulator for digital mobile radio enviroments is proposed, which enables the field tests in the laboratory under identical conditions, since it can reproduce the actual multipath radio channels by using the channel impulse responses (CIR's) measured in the field. Linear interpolation of CIR is introduced to simplify the structure of the proposed simulator. The performance of the proposed simulator is confirmed by the laboratory tests.

An approximate but sufficiently accurate high frequency solution is developed in this paper for analyzing the problem of electromagnetic plane wave scattering by an open-ended, perfectly-conducting, semi-infinite parallel-plate waveguide with a thin layer of lossy or absorbing material on its inner wall, and with a planar termination inside. The high frequency solution combines uniform geometrical theory of diffraction (UTD) and aperture integration (AI) methods. The present method has several advantages in comparison with other methods.

There have been several studies related to a reduction of the amount of computational resources used by Turing machines. As consequences, linear speed-up theorem" tape compression theorem", and reversal reduction theorem" have been obtained. In this paper, we consider reversal- and leaf-bounded alternating Turing machines, and then show that the number of leaves can be reduced by a constant factor without increasing the number of reversals. Thus our results say that a constant factor on the leaf complexity does not affect the power of reversal- and leaf-bounded alternating Turing machines

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.

As a new method to generate a homogeneous, random, binary image with a rational power spectrum, this paper proposes a discrete-valued auto-regressive equation, of which random coefficients and white noise excitation are all discrete-valued. The average and spectrum of the binary image are explicitly obtained in terms of the random coefficients. Some computer results are illustrated in figures.

Since, in a VLSI circuit, the number of transistors and the clock frequency are constantly increasing, it is important to analyze the voltage drop and current density on a full chip's power networks. We propose a new hierarchical power analysis system named XPOWER. A new reduction algorithm for the resistance and current source network is used in this system. The algorithm utilizes the design hierarchy in nature and is independent of network topology. Networks at each level are reduced into small and equivalent networks, and this reduction is performed recursively from the bottom levels of the design hierarchy. At each step of the reduction, the network under consideration consists of two kinds of objects: (1) reduced child networks, and (2) the interconnection between child networks. After all networks have been reduced, circuit equationa are solved recursively from the top. This allows to decrease the size of the matrix to be solved and to reduce the execution time. Experimental results show that the factor of reduction in matrix size is from 1/10 to 1/40 and execution is six times faster than with flat analysis. The power networks of a 16 bit digital signal processor was analyzed within 15 minutes using XPOWER.

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.

One of the most interesting and most analyzed aspects of the CPU design is the instruction set design. How many and which operations to be provided by hardware is one of the most fundamental issues relaing to the instruction set design. This paper describes a novel method that formulates the instruction set design of ASIP (an Application Specific Integrated Processor) using a combinatorial appoach. Starting with the whole set of all possible candidata instructions that represesnt a given application domain, this approach selects a subset that maximizes the performance under the constraints of chip area, power consumption, and functional module sharing relation among operations. This leads to the efficient implementation of the selected instructions. A branch-and-bound algorithm is used to solve this combinatorial optimization problem. This approach selects the most important instructions for a given application as well as optimizing the hardware resources that implement the selected instructions. This approach also enables designers to predict the perfomance of their design before implementing them, which is a quite important feature for producing a quality design in reasonable 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.

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.

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.

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.

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.

Evolution programs have been shown to be very useful in a variety of search and optimization problems, however, until now, there has been little attempt to apply evolution programs to channel routing problem. In this paper, we present an exolution program and identify the key points which are essential to successfully applying evolution programs to channel routing problem. We also indicate how integrating heuristic information related to the problem under consideration helps in convergence on final solutions and illustrate the validity of out approach by providing experimental results obtained for the benchmark tests. compared with the optimal solutions.

The transient scattering of a half sine pulse wave by a conducting rectangular cylinder with an open sidewall is rigorously analyzed by using the point matching method (taking into account the edge condition exactly) combined with the fast inversion of Laplace transform. Numerical results are presented for back scattered and forward scattered responses of the far fields when a half sine pulse is incident on the open side and the closed side of the cylinder. The physical meaning of the transient responses is discussed in detail. The comparison of the responses with those by a perfect conducting rectangular cylinder is presented.

Radar imaging technique is one of the most powerful tool for underground detection. However, performance of conventional methods is not sufficiently high when the observational direction or the aperture size is restricted. In the present paper, an image reconstruction method based on a model fitting with nonlinear least-squares has been developed, which is applicable to arbitrarily arranged arrays. Reconstruction is executed on the assumption that targets consist of discrete point scatterers embedded in a homogeneous medium. Model fitting is iterated as the number of point target in the assumed model is increased, until the residual in fitting becomes unchanged or small enough. A penalty function is used in nonlinear least-squares to make the algorithm stable. Fundamental characteristics of the method revealed with computer simulation are described. This method focuses a much sharper image than that obtained by the conventional aperture synthesis technique.