We have classified parenchymal echo patterns of cirrhotic liver into 3 types, according to the size of hypoechoic nodular lesions. We have been studying an ultrasonic image diagnosis system using the three–layer back–propagation neural network. In this paper, we will describe the applications of the neural network techniques for recognizing and classifying chronic liver disease, which use the nodular lesions in the Proton density and T2–weighed magnetic resonance images on the gray level of the pixels in the region of interest.

This paper presents a new numerical procedure for solving the scattering wave by the moving surface. Recently, the author and her colleagues have proposed a novel numerical procedure of grid generation having a coordinate line coincident with an arbitrarily shaped moving boundary. The time dependent curvilinear coordinate system which coincides with a contour of moving boundary in a physical region is transformed into fixed rectangular coordinate system. The simple form for the transformation is made possible to choose the function between the physical region and the rectangular computational region. The FD-TD algorithm is exactly solved in this fixed rectangular coordinate system. In this paper, for the application of the FD-TD algorithm to the body fitted grid generation with moving boundary, the stability criterion of FD-TD algorithm for the body fitted grid generation with moving boundary in three dimensions is derived. The stability criterion is shown an upper bound for time step assuring stable numerical solutions. The study of scattering of electromagnetic and acoustic wave from a moving or a rotating body is very important for electromagnetic probing of moving body. The problem has been investigated in the past by numerous authors. One of them is solved by FD-TD method, where the linear interpolation is introduced for the movement. By using the presented transformation technique where time component is added to the grid generation, the time depending coordinate system can be transformed into fixed rectangular coordinate system. Then the problems are directly solved by FD-TD method in the transformed coordinate system. To verify this numemical technique, scattered field is evaluated in the case when a plane wave is normally incident on a moving perfectly conducting flat plate. The numerical results are compared with the exact ones and excellent agreement between them is obtained.

In general, message passing multiprocessors suffer from communication overhead and shared memory multiprocessors suffer from memory contention. Also, data I/O overhead limits performance. In particular, computer vision tasks that require massive computation are strongly affected by these disadvantages. This paper proposes new parallel architectures for computer vision, a Flexibly (Tightly/Loosely) Coupled Multiprocessor (FCM) and a Flexibly Coupled Hypercube Multiprocessor (FCHM) to alleviate these problems. FCM and FCHM have a variable address space memory in which a set of neighboring memory modules can be merged into a shared memory by a dynamically partitionable topology. FCM and FCHM are based on two different topologies: reconfigurable bus and hypercube. The proposed architectures are quantitatively analyzed using computational models and parallel vision algorithms are simulated on FCM and FCHM using the Intel's Personal SuperComputer (iPSC), a hypercube multiprocessor, showing significant performance improvements over that of iPSC.

A coupled-mode analysis of a symmetric planar nonlinear directional coupler (NLDC) is presented by using a singular perturbation scheme. The effects of linear coupling and nonlinear modification of refractive index are treated to be small perturbations, and the modal fields of isolated linear waveguides are employed as the basis of propagation model. The self-consistent first-order coupled-mode equations governing the transfer of optical power along the NLDC are obtained in analytically closed form. It is shown that tha critical power for optical switching derived from the coupled-mode equations is in close agreement with that obtained by the numerical analysis using the finite difference beam propagation mathod.

With advances in the speed, bandwidth and reliability of telecommunications networks and in the performance of workstations, distributed processing has become widespread. Information sharing among distributed nodes and its mutual exclusion are of great importance for efficient distributed processing. This paper systematizes and quantitizes a shared memory called Data-Cyclic Shared Memory (DCSM) from the viewpoints of memory organization and access mode. In DCSM, the propagation delay of transmission lines and the data relaying delay in each node are used for information storage, and memory information encapsuled in the form of "memory cells" circulates infinitely in a logical ring type network. The distinctive feature of DCSM, in addition to the way data is stored, is that data and the access control are completely distributed, which contrasts with existing memory where both are centralized. Therefore, there are no performance bottlenecks caused by concentrating memory access. Distributed Shared Memory (DSM), which has a scheme similar to DCSM's, has also been proposed for distributed environments. In DSM, the data is also distributed but the control for accessing each data is centralized. From the viewpoints of memory organization and the access method, DCSM is very flexible. For instance, word length can be spatially varied by defining data size at each address, and each node can be equipped with mechanisms for special functions such as the content address specification and asynchronous report of change in contents. Because of this flexibility, it can be called a "software-defined memory." The analysis also reveals that DCSM has the disadvantages of large access delay and small memory capacity. The capacity can be enlarged by inserting FIFO type queues into the circulation network, and the delay can be shortened by circulating replicas of original memory cells. However, there is a trade off between the maximal capacity and the mean access time. DCSM has many potential applications, such as in the mutual exclusion control of distributed resources.

A new algorithm, which is incorporated into the waveform relaxation analysis, for efficiently simulating the transient response of single lossy transmission lines or lossy coupled multiconductor transmission lines, terminated with arbitrary networks will be presented. This method exploits the inherent delay present in a transmission line for achieving simulation efficiency equivalent to obtaining converged waveforms with a single iteration by the conventional iterative waveform relaxation approach. To this end we propose 'line delay window partitioning' algorithm in which the simulation interval is divided into sequential windows of duration equal to the transmission line delay. This window scheme enables the computation of the reflected voltage waveforms accurately, ahead of simulation, in each window. It should be noted that the present window partitioning scheme is different from the existing window techniques which are aimed at exploiting the non–uniform convergence in different windows. In contrast, the present window technique is equivalent to achieving uniform convergence in all the windows with a single iteration. In addition our method eliminates the need to simulate the transmission line delay by the application of Branin's classical method of characteristics. Further, we describe a simple and efficient method to compute the attenuated waveforms using a particular form of lumped element model of attenuation function. Simulation examples of both single and coupled lines terminated with linear and nonlinear elements will be presented. Comparison indicates that the present method is several times faster than the previous waveform relaxation method and its accuracy is verified by the circuit simulator PSpice.

By applying Wigner distribution, which has high time resolution and high random noise reducing capability, to the acoustic bio–signals, the possibility of early diagnosis in both intracranial vascular deformation and prosthetic cardiac valve malfunction increased. Especially in latter case, 1st–order local moment of the distribution showed its effectiveness.

In this paper we propose a formal linearization method which permits us to transform nonlinear systems into linear systems by means of the Chebyshev interpolation. Nonlinear systems are usually represented by nonlinear differential equations. We introduce a linearizing function that consists of a sequence of the Chebyshev polynomials. The nonlinear equations are approximated by the method of Chebyshev interpolation and linearized with respect to the linearizing function. The excellent characteristics of this method are as follows: high accuracy of the approximation, convenient design, simple operation, easy usage of computer, etc. The coefficients of the resulting linear system are obtained by recurrence formula. The paper also have error bounds of this linearization which show that the accuracy of the approximation by the linearization increases as the order of the Chebyshev polynomials increases. A nonlinear filter is synthesized as an application of this method. Numerical computer experiments show that the proposed method is able to linearize a given nonlinear system properly.

A three-dimensional analysis of Whispering-Gallery modes (W. G. modes) in a coaxial dielectric resonator is proposed and presented. The coaxial dielectric resonator is constructed from a lossy dielectric disk and ring which have diameters of several tens times as large as wavelength. Eigenvalue equations of the W. G. modes are derived rigorously from field expressions and boundary conditions. The resonant frequencies, unloaded Q values and field distributions are calculated numerically from the eigenvalue equations. These calculated results are in good agreement with experimental ones for an X band model. As a result, it is shown that a considerable quantity of modal energy can be confined in a loss-less gap between the disk and ring, and then the unloaded Q value is higher than that of a conventional dielectric disk and ring resonator.

The analytic structure of the governing equation for a 2nd order Phase–Locked Loops (PLL) is studied in the complex time plane. By a local reduction of the PLL equation to the Ricatti equation, the PLL equation is analytically shown to have singularities which form a fractal structure in the complex time plane. Such a fractal structure of complex time singularities is known to be characteristic for nonintegrable, especially chaotic systems. On the other hand, a direct numerical detection of the complex time singularities is performed to verify the fractal structure. The numerical results show the reality of complex time singularities and the fractal structure of singularities on a curve.

In this paper, a novel coupler-type wavelength demultiplexer composed of the K+-ion diffused waveguides, which has an adjustment function for optimizing the diffusion depth, is proposed to achieve reliably the high extinction ratio. The optimization in the diffusion depth is made by repeating the K+-ion diffusion and extinction-ratio measurement alternatively, and the high extinction ratios more than 20 dB are measured reliably at both operation wavelengths of 0.6328 and 0.83 µm. Experimental results on the polarization dependence in the extinction-ratio adjustment are also reported.

Coupling optics for a monolithic array LD module has been developed. High efficient and small sized confocal optics with aspheric lenses based on hyperbolic surfaces has been designed to achieve the uniformity of coupling loss. A small sized (7.2 cc) 4 channel array LD module with this optics was fabricated. This module has low (4.2 dB) and uniform (0.5 dB) coupling loss.

A new type of variable beam splitter at optical frequencies is proposed. The basic structure of the device utilizes a tapered velocity coupler which is composed of a center slab waveguide of constant-thickness, constant-index type and two identical outer slab waveguides of constant-thickness, variable-index type. The coupler is assumed to be fabricated on a LiNbO3 substrate, whith an external electric field applied in parallel with the optical axis. The numerical results obtained with the finite difference method show that a wide range of splitting ratios can be obtained with moderate drive voltages and that the splitting characteristics are stable over a wide range of frequencies.

Numerical simulations for the (3+1)-dimensional optical-field dynamics of nonstationary pulsed beams that propagate down Kerr-like nonlinear channel waveguides are carried out for what is to our knowledge the first time. Time-resolved intrapulse switching due to spontaneous symmetry breaking of optical fields from a quasilinear symmetric field to a nonlinear asymmetric field is analyzed. A novel instability phenomenon triggered by the symmetry breakdown is found.

The design theory was revealed by theoretical analysis of the measuring apparatus, and was confirmed experimentally. Higher quality tags having new circuit disigns were proposed by the revealed theory. The measuring apparatus equivalent to the security system was produced to estimate the properties of the LC resonant circuit security tags quantitatively.

For the purpose of detecting the intracranial vascular deformations noninvasively, transducer for bruit sound emanated from diseased lesion and analyzing system were developed and applied clinically. Several aspects of the bruit signals were clarified and the possibility of early diagnosis was increased.

We present a novel algorithm to reconstruct the refractive-index profile of a circularly symmetric object from measurements of the electromagnetic field scattered when the object is illuminated by a plane wave. The reconstruction algorithm is besed on an iterative procedure of matching the scattered field calculated from a certain refractive-index distribution with the measured scattered field on the boundary of the object. In order to estimate the convergence of the reconstruction, the mean square error between the calculated and measured scattered fields is introduced. It is shown through reconstructing several examples of lossy dielectric cylinders that the algorithm is quite stable and is applicable to high-contrasty models in situations where the Born approximation is not valid.

This paper presents a cost-effective network for very large ATM cross-connects. In order to develop it, we propose the delta network with expanded middle stages. This proposed network is the intermediate network between a nonblocking network and the delta network with respect to the cost of hardware and internal blocking probability. Using this network, we explore the tradeoff between the cost and internal blocking probability, and derive the optimum configuration under temporarily deviating traffic. Internal blocking occurs when input traffic temporarily deviates from its average value. However, we cannot evaluate the internal blocking probability by using conventional traffic models. In this paper, we adopt temporarily deviating traffic such that all traffic is described as the superposition of the paths which are defined by traffic parameters. As can easily be seen, the path corresponds to virtual path (VP) or virtual channel (VC). Therefore, we believe that our model describes actual traffic more exactly than conventional models do. We show that the optimum configuration is the proposed network whose expansion ratio γ=3 when the maximum number of paths that can be accommodated in one link is greater than 22. This network achieves the internal blocking probability of 10-10. As an example of this network, we show that the proposed network of size 7272 is constructed with only 40% of the hardware required by the nonblocking network.

Given a sorted set S of n points in the plane, the prefix convex hulls problem of S is to compute the convex hull for every prefix set of S. We present a parallel algorithm for this problem. Our algorithm runs in O(logn) time using n/logn processors in the CREW PRAM computational model. The algorithm is shown to be time and cost optimal. One of the techniques we adopt to achieve these optimal bounds is the use of a new parallel data structure Array-Tree.

Creating a bandwidth abundant B-ISDN requires the further development of path technologies. Optical path cross-connect nodes (OXCs) will be required that offer very high levels of expandability. The present limited traffic demands must be efficiently supported while permitting easy step-wise expansion in capacity. This paper proposes two OXC architectures that offer high modularity with regard to incoming/outgoing links or the number of multiplexed wavelengths in each link. This paper briefly reviews, for optical path realization, the wavelength path (WP) and the virtual wavelength path (VWP) techniques. The proposed OXC architectures provide flexibility and minimum investment to encourage introduction but support incremental network growth and investment to match traffic demand. The architectures make it easy to upgrade a WP network to a VWP network, simply by replacing some optical components. It is also shown that the proposed OXC architectures ensure effective optical signal detection after a long-haul optical fiber transmission because they minimizes signal power losses within the OXC. Therefore, the proposed OXC architecture can be applied to global area networks. The proposed OXC architectures will play a key role in realizing the optical path infrastructure for the future bandwidth abundant B-ISDN.