A distributed clocking scheme for ANSI FDDI- is considered. To compensate for clock variability, a frame proceeding through a series of stations has its preamble bits added or deleted. The necessary preamble size for stable operation is calculated, based on a Gumbel distribution fitted to a simulation result.

The paper deals with a single server queue with two priority classes of customers. The arrival process for the high-priority class is assumed to be Poisson, while the interarrival time for the low-priority class is allowed to have a general distribution. Work-conserving rules, especially the non-preemptive rule and the preemptive-resume rule, are studied. A relationship between the unfinished work and the waiting times for both priority classes is derived. Numerical calculation for the unfinished work is not so easy, because the queueing model considered here contains the GI/G/1 model. Using a diffusion approximation for the unfinished work process, new approximate formulas for the performance measures are obtained explicitly. If the arrival process for the low-priority class is also Poisson, the formulas are consistent with the classical exact results. Numerical examples and comparisons with simulation results are presented. They indicate that the approximate formulas proposed here are accurate as compared with those presented in the previous works.

Many software reliability growth models have been proposed in the last decade, based on software error data observed during testing phase in the software development. However, the existing models are insufficient to represent the time-dependent behavior of testing-effort expenditures in the actual environment of the software testing. For this reason we develop and investigate a testing-effort dependent reliability model incorporating the testing-effort spent on software testing into the software reliability growth. The model is described by a non-homogeneous Poisson process, assuming that the error detection rate to the amount of testing-effort spent at an arbitrary testing time is proportional to the current error content. The time-dependent behavior of testing-effort expenditures is described by a Weibull curve due to the flexibility. From this model, the quantitative software reliability measures are derived. The estimations for the testing-effort parameters and the reliability growth parameters in the model are given by a method of least-squares and by a method of maximum-likelihood, respectively. Then, statistical inferences on the model parameters and the software reliability measures, and analyses of actual software error data and studied.

A new burner with a multi-flame structure is proposed for high-rate fabrication of optical fiber preforms in the vapor-phase axial deposition process (VAD). In this multi-flame VAD process, the synthesis of fine glass particles was clarified and the fabrication of soot preforms was investigated together with the consolidation process. As a result, a deposition rate of 4.5g/min was achieved using one double-flame burner. Graded-index core preform size was increased to 2500g. In addition, fibers with a high numerical aperture (N.A.) of 0.28 were fabricated using a double-flame burner. A transmission loss at 1.62µm was 0.54dB/km and the bandwidth at 1.3µm was 440 MHz km.

Magnetic particles such as Fe3O4 and - Fe2O3 introduced into hamster pulmonary macrophages were used as a probe for intracellular motility and the rate of phagocytosis. Magnetic particles within the macrophages produce a weak magnetic field around the cells when magnetized with a strong external magnetic field. The field decays with time with a half time less than 5-6 minutes. This decay called relaxation has been recently associated with intracellular movements of microstructures of the cells. In this paper we present the results of relaxation measurements under the influence of inhibitors of ATP synthesis. We also measured the change of relaxation rate during phagocytosis (taking up of the particles by the cells.) The inhibitors notably decreased the rate of relaxation as had been expected. The decrease in the rate of relaxation corresponded well to the decrease in intracellular ATP concentration which was measured by the luciferin-luciferase method. The change of relaxation during phagocytosis of magnetic particules by pulmonary macrophages was clearly seen.

Simple and closed form expressions for reflection and transmission coefficients of a thin strip grating on a dielectric sheet are presented for the use of antenna application. In the analysis, a set of integral equations for the aperture fields between strips are derived from the three dimensional boundary value problem. Upon use of the low frequency approximation, closed form expressions are obtained for reflection and transmission coefficients. The accuracy of our approximation results is examined numerically by making use of the Point Matching Method. It is shown that the accuracy is excellent provided 1) the period of gratings is smaller than about 0.3 free space wavelength, and 2) the thickness of the dielectric sheet is greater than about 0.3 times the grating period.

Scattering of plane electromagnetic wave by a semi-infinite strip grating has been analyzed under the assumption that the strip is narrow relative to the wavelength. Numerical results are given for some diffraction patterns.

A quaternary Boolean ring structure is introduced to the four-element set L={0,,,1}, which is the only Boolean ring structure possible on it; the set of logic functions on L and L2 expressible over the ring is extended from the Boolean polynomials to the entire logic functions; the extension becomes possible after inclusion of two non-Boolean polynomials in the basis, where the number is the smallest possible one. A one-to-one mapping between L and {0,1,2,3} is made, and resulting arithmetic operations on L are make explicit in the form of monadic or dyadic functions.

This letter describes a method to estimate the power-spectrum of speech signals with additive white noise, based on the maximum likelihood principle and numerical maximization of the likelihood function. Some examples of the estimated spectral patterns for Japanese vowels are presented.

By using complementary SIT, a new type of power negative-resistance device with lambda-type I-V characteristic is presented. It is expected to be realized that the peak current of the proposed device is more than 1500 mA. The new device is characterized by advantageous features such as high-speed performance and wide current-voltage range.

This paper shows a novel automatic classification method for the electroencephalogram (EEG) based on syntactical pattern recognition. The syntactical method is effective to represent the complicated structure of the features of the EEG which contains transient-waves as well as the background-wave. For the extraction of transient-waves an adaptive autoregressive-moving average (ARMA) model fitting is utilized where the input to the model is replaced by the modified input if the prediction error grows more than a given threshold. By the adaptive ARMA model transient-waves and the spectrum of the background-wave are obtained from the prediction error and ARMA parameters, respectively. Since transient-waves may contain noisy patterns or variances, a relaxation scheme is applied. As the second stage all of the features of the EEG including the spectrum are described syntactically according to the generative grammar. Then the syntactical description Ti inherent to the diagnosis is obtained. In order to reduce the ambiguity and to suppress the complexity of syntactical descriptions, numerical values representing the details of EEG are separated from the syntactical description, and are added as the attributes (this method is generally called the attributed grammar). For the input EEG having syntactical description Ti, the final diagnostic decision is made by using the statistical Bayes estimation about the attributes within the group for Ti. As the result of automatic EEG classification for 200 EEG samples correct recognition of about 80 percent is observed.

The computational complexity of several problems in compacting LSI layouts are reviewed from the viewpoint of network flow theory and algorithms. It is shown that the general one-dimensional compaction problem of an LSI layout with n elements, such that the basic building blocks are rectilinear polygons connected by stretchable/shrinkable and movable wires, can be solved in O(n log n) time. Related problems of updating constraints on the layout are also considered.

In order to achieve high speed measurements of acoustic parameters needed for evaluating pathological voice, an integrated voice analyzer (IVA) has been developed by using a digital signal processor and a general purpose microprocessor. By utilizing a personal computer as a controller of the IVA, a versatile system can be constructed for the acoustic evaluation of pathological voice.

This paper presents the development of high-speed logic ICs having the same function as the ECL100K family for high-speed digital system applications such as for time division switching systems. A Super-Self-Aligned process Technology (SST) and a low-voltage swing differential circuit technique are used. The ICs operate up to about 2 Gb/s under a chip power dissipation of 170 mW570 mW.

A normalized norm between the time series of radar and gauge rain rates is defined as a measure of agreement between them. The calibration constant of a radar for rain measurements is determined to be the value which minimizes the normalized norm between the radar and gauge rain rates. The results of the experiment show the rain-to-rain variation of the calibration constant. The variation can be partly explained as due to the variation of raindrop size distribution.

A fast parallel sorting algorithm on a mesh-connected processor array is presented. The algorithm is based on a pseudo-merge algorithm that roughly merges four roughly sorted subfiles. Its computing time for sorting N items is 6+3log213 steps. We also discuss lower bounds on computing times for four classes of parallel sorts, bubble merge sorts, bubble-exchange merge sorts, bubble pseudo-merge sorts and bubble-exchange pseudo-merge sorts. It is shown that 4.54log2 steps, 3.52log21 steps, 34log2+3 steps and 2.5log21 steps, are lower bounds for these classes, respectively.

On the basis of the controllability gramians, the observability gramians and the second order modes, this paper shows that optimal realizations (filter structures having minimum roundoff noises) of quarter-plane-causal, recursive and separable in denominator 2-D digital filters (CRSD filters for short) are scaled and rotated balanced realizations. Two applications of this relation are given. The first one gives a simple proof of the absence of overflow oscillations in optimal realizations. The second one, which is the main result of this paper, gives a direct design method of CRSD filters in the spatial domain. This method simplifies traditional two-step design (approximation and synthesis) into a one-step design with much less computational complexity. Resulting filters of this direct design method can approximate given 2-D impulse responses closely. In addition, they are always guaranteed to be stable, nearly optimal with respect to roundoff noise and free of overflow oscillations. The efficiency of the direct design method is shown by numerical examples.

The parsing method which analyzes sentences into trees may be divided into two categories, the procedural method and the filtering method. The former composes a tree avoiding the occurrence of improper analysis in the course of the analysis procedure by strictly defining the order of application of transformation rules concerning tree structure. The latter obtains the proper tree by obtaining, first, many analysis results through unlimited application of existing rewriting rules and by, later, eliminating improper trees with a filter. The former includes the parsers in the ARIANE 78 at Grenoble University and also at the group led by Kyoto University. This paper proposes a parsing method using the above-mentioned filtering scheme. The method is based on extended LINGOL which is included in the latter category and uses forbidden trees and exclusive trees which respectively forbid and foster the sentence pattern contained in these trees. These trees, cooperating together, work to filter out spurious results. The paper also treats OR nodes for expression of multiple trees in a single tree, giving an algebraic means to allow coexistence of OR nodes and the above-mentioned forbidden and exclusive trees. The algorithm presented in this paper has proved to act well in practical computer experiment showing that it is extensible for practical use.

This paper describes the characteristics of multipath fading in aeronautical satellite communications by mainly applying the maritime fading model.

Monolithic integrated-optical matrix switches (LD matrix SW's) using laser diode gain guides have been proposed. LD matrix SW's have been fabricated on a 1.5 µm-DH wafer by a dry process and optical switching has been demonstrated.