This paper presents a routing methodology and a routing algorithm used in designing Gb/s LSIs with deep-submicron technology. A routing method for controlling wire width and spacing is adopted for net groups classified according to wire length and maximum-allowable-delay constraints. A high-performance router using this method has been developed and can handle variable wire widths, variable spacing, wire shape control, and low-delay routing. For multi-terminal net routing, a modification of variable-cost maze routing (GVMR) is effective for reducing wire capacitance (net length) and decreasing net delay. The methodology described here has been used to design an ATM-switch LSI using 0. 25-µm CMOS/SIMOX technology. The LSI has a throughput of 40 Gb/s (2. 5 Gbps/pin) and an internal clock frequency of 312 MHz.

In this paper, we propose a technique to synthesize a hardware circuit from a protocol specification consisting of several concurrent EFSMs with multi-rendezvous specified among their subsets. In our class, each multi-rendezvous can be specified among more than two EFSMs, and several multi-rendezvous can be specified for different combinations of EFSMs. In the proposed technique, using the information such as current states of EFSMs, input values at external gates and guard expressions, we compose a circuit to evaluate whether each multi-rendezvous can be executed. If several exclusive multi-rendezvous get executable simultaneously for some combinations of EFSMs, we select one of them according to the priority order given in advance. We compose such a circuit as a combinational logic circuit so that it works fast. By applying our technique to Abracadabra protocol specified in LOTOS, it is confirmed that the derived circuit handles multi-rendezvous efficiently.

In this paper, we give a new approach to the computation of primary decomposition and associated prime components of a zero-dimensional polynomial ideal (f1,f2,. . . ,fn), where fi are multivariate polynomials on Z (the ring of integer). Over the past several years, a considerable number of studies have been made on the computation of primary decomposition of a zero-dimensional polynomial ideal. Many algorithms to compute primary decomposition are proposed. Most of the algorithms recently proposed are based on Groebner basis. However, the computation of Groebner basis can be very expensive to perform. Some computations are even impossible because of the physical limitation of memory in a computer. On the other hand, recent advance in numerical methods such as homotopy method made access to the zeros of a polynomial system relatively easy. Hence, instead of Groebner basis, we use the zeros of a given ideal to compute primary decomposition and associated prime components. More specifically, given a zero-dimensional ideal, we use LLL reduction algorithm by Lenstra et al. to determine the integer coefficients of irreducible polynomials in the ideal. It is shown that primary decomposition and associated prime components of the ideal can be computed, provided the zeros of the ideal are computed with enough accuracy. A numerical experiment is given to show effectiveness of our algorithm.

A new learning method is proposed to enhance the performances of the fuzzy ARTMAP neural network in the noisy environment. It combines the average learning and slow learning for the weight vectors in the fuzzy ARTMAP. It effectively reduces a category proliferation problem and enhances recognition performance for noisy input patterns.

Coulombs law of friction, in which the coefficient of friction is constant independently of apparent area of contact and applied load, is deduced from the modern adhesion theory. That is, the friction resistance is caused by shearing of solid/solid junctions which are formed through plastic deformation of surface asperities of mating solids. In so-called point contact, on the other hand, different experimental results from Coulombs law have been sometimes reported. In these cases, coefficient of friction is not constant, but reduces with increasing normal load. A weighty interpretation for these facts developed formerly is that Hertzian contact area acts as an effective zone to generate the friction resistance. This interpretation has, however, an important doubt, as the Hertzian contact area is not formed through plastic but through elastic deformation of solids. If the friction resistance is generated in an elastic contact area, the adhesion theory of friction would be shaken at its standing basis. To give an explanation of this inconsistency between the experimental facts reported previously and the adhesion theory of friction, the authors propose a new idea in this paper. The plastic deformation occurs at surface asperities even in Hertzian contact. If the rubbing condition is kept dry, the friction resistance would be generated only at those plastically deformed zone dotted in the elastic contact area, so that Coulombs law is realized. If the rubbing condition is kept wet, the clearance between mating surfaces in the elastic contact zone is filled with any lubricant or contaminant molecules, the friction resistance would be generated through shearing of them within the Hertzian area. In this case, the coefficient of friction would be proportional to(load)-1/3, which is close to observational facts reported previously. An experimental verification made in this study can describe the authors proposal.

This paper presents a design approach for developing MU-type single-mode miniature optical connectors featuring 1. 25 mm diameter zirconia ferrules. They are smaller and have a higher packaging density than conventional optical connectors. The ferrule pitch is 1/2, the plug volume 2/5 and the cross-sectional area 2/5 that of the SC connector. The aim of our approach is to reduce the ferrule size and to realize durable connectors. With 10/125 SM fibers, these MU connectors produced an average insertion loss of 0. 07 dB and an average return loss of 49. 4 dB, and there was no degradation during or after mechanical and environmental tests.

The electromagnetic interference (EMI) induced by steady arc has been demonstrated to be dependent on arc voltage fluctuation when the arc transfers from the metallic phase to the gaseous phase. In order to give the physical understanding of this arc voltage fluctuation and EMI, several typical materials, such as Ag, Cu and Zr, were tested and their arc behavior was determined and compared. The experimental results indicated that the arc behavior, in particular the arc voltage fluctuation in the moment that metallic phase transfers to the gaseous phase was different for different materials. Based on the test results and former investigations, a plausible mechanism is proposed for understanding these phenomena.

Given a binary picture represented by a region quadtree, it is desirable to identify the amount of (rightward and downward) shifts of the foreground components such that it gives the minimum number of nodes of its quadtree. This problem is called "quadtree normalization. " For this problem, it is unknown whether there exists a linear time algorithm with respect to the size of given images (i. e. , the number of pixels). In this study, we investigate the "one-dimensional version" of the quadtree normalization problem, i. e. , given a binary string represented by a regional binary tree, the task is to identify the amount of (rightward) shift of the foreground components such that it gives the minimum number of nodes of its binary tree. We show that there exists a linear time algorithm for this version.

This paper investigates some Z4 codes formed as the Z4-analog (Hensel lifting) of the binary BCH construction. Such codes with length 105 and dimension 13 have been constructed. They are described with their parameters. Some examples of their generator polynomials are given when Hamming weight and Lee weight are different.

The characteristics of circular polarization from a slot with a parasitic dipole are investigated analytically. It is derived that its phase is linearly dependent upon the angle of the dipole and is independent of that of slot. This interesting behavior is also confirmed by experiments.

The lower-bounded p-collection problem is the problem where to locate p sinks in a flow network with lower bounds such that the value of a maximum flow is maximum. This paper discusses the cover problems corresponding to the lower bounded p-collection problem. We consider the complexity of the cover problem, and we show polynomial time algorithms for its subproblems in a network with tree structure.

A training data selection method is proposed for multilayer neural networks (MLNNs). This method selects a small number of the training data, which guarantee both generalization and fast training of the MLNNs applied to pattern classification. The generalization will be satisfied using the data locate close to the boundary of the pattern classes. However, if these data are only used in the training, convergence is slow. This phenomenon is analyzed in this paper. Therefore, in the proposed method, the MLNN is first trained using some number of the data, which are randomly selected (Step 1). The data, for which the output error is relatively large, are selected. Furthermore, they are paired with the nearest data belong to the different class. The newly selected data are further paired with the nearest data. Finally, pairs of the data, which locate close to the boundary, can be found. Using these pairs of the data, the MLNNs are further trained (Step 2). Since, there are some variations to combine Steps 1 and 2, the proposed method can be applied to both off-line and on-line training. The proposed method can reduce the number of the training data, at the same time, can hasten the training. Usefulness is confirmed through computer simulation.

Digital signal processors (DSPs) usually employ indirect addressing using an address register (AR) to indicate their memory addresses, which often introduces overhead codes in AR updates for next memory accesses. In this paper, AR update scheme is extended such that address can be efficiently modified by 2 in addition to conventional 1 updates. An automatic address allocation method of program variables for this new addressing model is presented. The method formulates program variables and AR modifications by a graph, and extracts a maximum chained triangle graph, which is accessed only by AR 1 and 2 operations, so that the estimated number of overhead codes is minimized. The proposed methods are applied to a DSP compiler, and memory allocations derived for several examples are compared with memory allocations by other methods.

This paper studies a congestion control scheme in integrated variable bit-rate video, audio and data (e. g. , image or text) communications, where each video stream is synchronized with the corresponding audio stream. When the audio and video streams are output, media synchronization control is performed. To avoid congestion, we employ a dynamic video resolution control scheme which dynamically changes the video encoding rate according to the network loads. By simulation, the paper evaluates the performance of the scheme in terms of throughput, loss rate, average delay, and mean square error of synchronization. Numerical results show the effectiveness of the scheme.

Widely tunable coherent terahertz (THz)-wave generation was successfully demonstrated based on the laser light scattering from the lowest A1-symmetry polariton mode by using a Q-switched Nd:YAG laser pumping. This method exhibits multiple advantages like wide tunability (frequency: 0. 9-2. 2 THz), coherency and compactness of its system. In this paper, the general performances of this THz-wave generator, as well as the recent development of the system and its application are reported. Measurements of tunability, coherency, power, polarization, radiation angle, and divergence are shown. The cryogenic cooling of the crystal was performed in addition, and a more than one hundred times higher THz-wave output was observed. A spectroscopic application of our wave source is demonstrated by measuring the water vapor absorption.

It is shown from the Hilberts theory that if the real function Π(θ) has no zeros over the interval [0, 2π], it can be factorized into a product of the factor π+(θ) and its complex conjugate π-(θ)(=). This factorization is tested to decompose a real far-zone field pattern having zeros. To this end, the factorized factors are described in terms of bicomplex mathematics. In our bicomplex mathematics, the temporal imaginary unit "j" is newly defined to distinguish from the spatial imaginary unit i, both of which satisfy i2=-1 and j2=-1.

In this paper, we develop a novel method for tuning parameters known as the sensitivity parameters of membership functions used in a fuzzy classifier. The proposed method performs tuning by solving a set of inequalities. Each inequality represents a range of the ratio of the sensitivity parameters between the corresponding pair of classes. The range ensures the maximum classification rate for data of the two corresponding classes used for tuning. First, we discuss how such a set of inequalities is derived. We then propose an algorithm to solve the derived set of inequalities. We demonstrate the effectiveness of the proposed tuning method using two classification problems, namely, classification of commonly used iris data, and recognition of vehicle licence plates. The results are compared with those obtained by using the existing tuning method and with those by neural networks.

Optimization of InGaAs/InAlAs multiple quantum well structures for high-speed and low-driving modulation, as well as polarization insensitivity and low chirp, was investigated as a function of well thickness and strain magnitude. As a result, very short optical pulses with 4-6 ps was obtained using a low driving-voltage (<2. 0 Vpp) electroabsorption modulator module operating at a 40-GHz large signal modulation. Small chirp operation for low insertion loss (<8 dB from fiber-to-fiber) with prebias was also demonstrated and the product of the pulse width and the spectral width was estimated to be 0. 39 for a 5 ps pulse width that is nearly transform-limited.

The development of a far-infrared imaging system based on ultrafast THz time-domain spectroscopy has opened a new field of applications of femtosecond technology. We describe the principle of this new imaging technique and report recent progress to augment the possibilities of "T-ray" imaging. These include sub-wavelength-resolution near-field imaging and three-dimensional tomographic reconstruction of a samples refractive index profile.

We investigate the relaxation oscillation characteristics of an actively mode-locked fiber laser and a novel stabilizing method of the laser theoretically and experimentally. The stabilizing method controls cavity length to suppress the rf power of the relaxation oscillation frequency of the laser output, and can directly monitor the stability of the laser to ensure the most stable operation. With this method, the rf power ratio between mode-locking frequency and the background noise can be kept to more than 70 dB, and highly stable transform-limited pulse generation is achieved. Bit-error-free operation at 6. 3 GHz over 10 hours is successfully demonstrated. The stability of the center wavelength of the laser output and the required accuracy of cavity control for high-speed laser operation are also discussed.