The paper proposes and reports on pototyping a work bench system for novice Prolog programmers which consists of a visually-structured interactive tracer and a prototype-based programming support. The tracer actually is a simulated interpreter in Prolog. It is interpreted by a Prolog interpreter being embedded with facilities interfacing programs in Prolog and the objects programmed in C. It displays, by way of these objects, the past, current and future goals, highlights variable sharing and value substitution, and marks the current goals and backtrack choice points. It is at user's will to let the tracer show and hide subgoals as well as to let it backtrack when it failed, step back for redoing or terminate tracing. The programming support module first provides the programmer with structural prototype patterns and the roles of the constituent functions. We developed a support system for the 2 types of recursive definitions. After having selected the prototype, the user is requested to specify the data types and the names of variables to be put in the arguments, which propagate through the structure. The support module then offers a menu of primitive or user-registered constituent functions as may be useful in processing and/or obtaining user-specified types of data. Thirdly the system lets the user express his/her intention by sample input-output data instances in his/her task goals. It makes the values propagate through the structures thus motivating the user to design the constituent functions. At the goal recursion point, the user is allowed to creep into examining the definitions of the reduced versions of the instances, helping the user find the condition with which the recursion terminates. Finally the module assists the user to convert the structural descriptions into Prolog programs.

We propose an optical computing architecture called pure optical parall array logic system (P-OPALS) as an instance of sophisticated optical computing system. On the P-OPALS, high density images can be processed in parallel using the optical system with high resolving power. We point out problems on the way to develop the P-OPALS and propose logical foundation of the P-OPALS called single-input optical array logic (S-OAL) as a solution of those problems. Based on the proposed architecture, an experimental system of the P-OPALS is constructed by using three optical techniques: birefringent encoding, selectable discrete correlator, and birefringent decoding. To show processing capability of the P-OPALS, some basic parallel operations are demonstrated. The results obtained indicate that image consisting of 300 100 pixels can be processed in parallel on the experimental P-OPALS. Finally, we estimate potential capability of the P-OPALS.

It has been 15 years since we started producing the electric double-layer capacitors (also known as Super Capacitor) in 1978. Over the years we have introduced improvements that increased reliability and increased life. For example, after subjecting capacitors manufactured in 1984 and 1990 to load life tests (70, 5.5 V) for 2,000 hours, we discovered that the rate of change in capacitance (ΔC/C) of capacitors manufactured in 1990 was less than one-half that of capacitors manufactured in 1984. This shows that we have successfully increased the life of our electric double-layer capacitors. We conducted investigations regarding factors that contribute to volume of the electrolyte solution and better sealing properties. In the load life test, we observed that when the ratio of the weights of the electrolyte solution and the powdered activated carbon (hereinafter referred to as LB) was increased, the time it took before ΔC/C reached -30% was lengthened. This means that increasing LB also increases life. Furthermore, we also observed that when the gas permeability rate of the collector's rubber material was decreased in the load life test (70, 5.5 V), the time it took befor (ΔC/C) reached -30% was longer. Therefore life is dependent on the gas permeability rate (sealing property) of the collector rubber.

A new effect of barrier metal laid under 1st aluminum layer on electromigration has been found in interconnect vias. This effect can be explained by Si nodules at vias. Stress induced open failure occurred at viaholes and depends on the size of the vias. Stress-migration at vias can be prevented by TiN barrier metal between 1st and 2nd metals. Reliability of electro- and stress-migration at interconnect vias can be explosively improved by using TiN barrier metal.

This paper describes the reliability on recess type T-shaped gate HEMTs and their major failure mechanism investigated by accelerated life tests and following failure analysis. In this study, high temperature storage tests with a DC bias condition have been conducted on three different recess depths of 100, 125, and 150 nm. The results have clarified that the shallow recess devices of under 125 nm depth have no degration in minimum noise figure Fmin or gain Ga characteristics, indicating that standard HEMT devices, whose recess depth is chosen to be far under 125 nm, possess a sufficient reliability level. However, the devices with deep recess of 150 nm have shown degradation in both Fmin and Ga. Precise failure analyses including SEM observation and von Mises stress simulation have firstly revealed that the main failure mode in deeply recessed T-shaped gate HEMTs is increase in gate electrode's parasitic resistance Rg, which is caused by separation of "head" and "stem" parts of the T-shaped gate electrode due to thermo-mechanical stress concentration.

Narrow emitter effects in self-aligned bipolar transistors are discussed. Besides the increase of a non-ideal base current, the decrease of an ideal base current is newly observed, and a consequent fluctuation of the current gain becomes wider in the smaller emitter geometry. Both phenomena are attributed to the reduction of an emitter-impurity concentration.

Finding DC solutions of nonlinear networks is one of the most difficult tasks in circuit simulation, and many circuit designers experience difficulties in finding DC solutions using Newton's method. Piecewise-linear analysis has been studied to overcome this difficulty. However, efficient piecewiselinear algorithms have not been proposed for nonlinear resistive networks containing the Gummel-Poon models or the Shichman-Hodges models. In this paper, a new piecewise-linear algorithm is presented for solving nonlinear resistive networks containing these sophisticated transistor models. The basic idea of the algorithm is to exploit the special structure of the nonlinear network equations, namely, the pairwise-separability. The proposed algorithm is globally convergent and much more efficient than the conventional simplical-type piecewise-linear algorithms.

When we use the finite-difference time-domain (FD-TD) method to study time-domain electromagnetic fields in the unbounded surroundings, we frequently use a radiation boundary condition (RBC) by means of one-way wave equations. The reflection coefficient by the RBC is independent of frequency, but the reflection coefficient of the finite difference approximation for the RBC depends on a frequency also; this study examines how the reflection characteristics are affected by the frequency, and the study presents the coefficients used in the RBC which gives expected reflection characteristics for a frequency, and presents the application to simulation of the matched termination of a rectangular waveguide.

Expressions for electromagnetic fields generated by vertical and horizontal electric dipoles located in the air or in a lossy half-space near its boundary with air are obtained from Hertz vectors by the method of operators under the condition |n|31, where 1/n is the refractive constant of the lossy space. These can be applied up to the near fields under the additional conditions, |n|21 and cos2θ1, where θ is the zenith angle of the point of observation. As for recent works inclusive of expressions of lateral waves their weak points are pointed out.

This paper applies the principle of radar polarimetry to the synthetic aperture frequency modulated continuous wave radar. First, the principle of monochromatic wave radar polarimetry using scattering matrix and polarization ratio necessary for introducing polarimetric imaging is given. In order to accommodate this principle to a wideband radar, a scattering matrix must be introduced, because FM-CW radar utilizes a wideband signal. This paper points out that the polarimetric target reflection coefficient obtained by the synthetic aperture FM-CW radar works as the scattering matrix element. This replacement, i.e., polarimetric reflection coefficient = the scattering matrix element, was verified by an experiment based on the polarization ratio which maximizes and minimizes a target. A radar system operative in the microwave X-band was successfully applied to the polarimetric detection of a metallic pipe of different orientations, demonstrating the validity of FM-CW radar polarimetry, and indicating an establishment of full polarimetric radar system.

The student model component of intelligent tutoring systems (ITSs) used to be considered central: it was the means by which the ITS could individually adapt the learning experience to suit the learner's perceived needs. However, the practical difficulty of building reliable student models, the evolution away from the knowledge communication style of ITSs towards a more constructivist philosophy, and the development of new media to support learning interactions have all combined to question the role (if any) for student models in current interactive learning environments (ILEs). In this paper we will explore the new role of student models by considering the lessons learned from five Lancaster projects (SAFE, EPIC, PEOPLEPOWER, CLORIS and SMILE). The main issues revolve (as usual) around the questions of control and learning objectives.

This paper is concerned with the problem of (exactly) representing given functions by fuzzy reasoning. We consider function representation by the fuzzy reasoning method using linguistic truth values, which is a generalization of fuzzy reasoning due to Zadeh. Some conditions for functions to be representable are given, by which it is shown that very large class of functions can be representable by this method. Some examples illustrating how to find "if-then rules" for fuzzy reasoning are shown. Further, in the appendix an example is given to show that the generalization is significant for the problem of function representation.

This paper proposes a new combined fast algorithm for transversal adaptive filters. The fast transversal filter (FTF) algorithm and the normalized LMS (NLMS) are combined in the following way. In the initialization period, the FTF is used to obtain fast convergence. After converging, the algorithm is switched to the NLMS algorithm because the FTF cannot be used for a long time due to its numerical instability. Nonstationary environment, that is, time varying unknown system for instance, is classified into three categories: slow time varying, fast time varying and sudden time varying systems. The NLMS algorithm is applied to the first situation. In the latter two cases, however, the NLMS algorithm cannot provide a good performance. So, the FTF algorithm is selected. Switching between the two algorithms is automatically controlled by using the difference of the MSE sequence. If the difference exceeds a threshold, then the FTF is selected. Other wise, the NLMS is selected. Compared with the RLS algorithm, the proposed combined algorithm needs less computation, while maintaining the same performance. Furthermore, compared with the FTF algorithm, it provides numerically stable operation.

This paper points out that there are two types of claw free families with respect to a level of claw freeness. We formulate them as weak claw free families and strong claw free families. Then, we present sufficient conditions for each type of claw free families. (A similar result is known for weak claw free families.) They are represented as some algebraic forms of one way functions. A new example of strong claw free families is also given.

We found degraded output power due to discoloration of an abnormal epitaxial layer caused by supercooling of residual melt in liquid phase epitaxy (LPE) process of AlGaAs/GaAs heteroface solar cells developed to improve conversion efficiency of solar cells for satellites. We studied the discoloration mechanism and found effective methods for obtaning a good epitaxial layer. Using these results, we manufactured about 80,000 pieces of solar cells and employed them in the Japanese domestic Communication Satellite-3 (CS-3) launched by National Space Development Agency of Japan (NASDA). Five years after launch, these solar cells are still supplying the output power than predicted. This paper describes reliability improvements for the surface of epitaxial layer and successful results aftes 5 years of space operation.

Reflection type optical switches with intersecting waveguides and curved electrodes are newly proposed. The guided incident mode is expanded into an infinite spectrum of plane wavelets. The effects of light tunneling into the transmission port is taken care of by treating the 3-layer structure and using its reflection and transmission coefficients in estimation of the extinction ratios. It is found that the electrode curved in the form of an exponential spiral provides remarkably improved power reflectivity. This is because it poses a constant angle of incidence (smaller than the critical angle) to all variously oriented impinging wavelets. In this way, all plane wavelets are made to undertake total reflections. These total reflections result in considerably high extinction ratios to be achivable at the transmission port. It is also shown that the electrode length is shorter and the intersection angle is wider than those corresponding to a straight electrode. Therefore, it is concluded that the curvature of the electrode improves the switching characteristics of the device.

The paper studies a high-ranking node in a broadband integrated services digital network(B-ISDN). The input traffic is classified into two types: real-time and non-real-time. For each type of input traffic, we assume that the message arrival process is a batch Poisson process and that the message size is arbitrarily distributed so as to describe services from narrowband to wideband. We model the high-ranking node by a queueing system with multiple synchronous servers and two separate finite buffers, one for each type of traffic. We derive performance measures exactly by using a two-dimensional imbedded discrete-time Markov chain analysis, within which the transition probabilities are obtained via an application of the residue theorem in complex variables. The performance measures include the blocking probability, delay, and throughput.

Via electromigration (EM) performance of aluminum based metallization (AL) systems has been investigated for vias chains of 1500-4000 vias of 1.0 micron diameter. The results show that via EM lifetime can not be enhanced by a simple increase of M2 step coverage in AL/AL vias because the EM induced voids are formed at AL/AL via interface where electrons flow from Ml to M2 even in the case of very poor M2 step coverage. The voids are induced by the boundary layer in AL/AL vias, where a temperature gradient causes discontinuity of aluminum atoms flux. The failure location is not moved though via EM lifetime can be improved by controlling stress in passivation, sputter etch removal thickness and grain size of the first metal. Next, the effect of the boundary layer are eliminated by depositing titanium under the second aluminum or depositing WSi on the first aluminum. In the both cases, via EM lifetime are improved and the failure locations are changed. Especially WSi layer suppresses the voids formation rather than titanium. Models for the failure mechanism in each metallization system are further discussed.

This paper describes the use of optical interconnections in switching systems and discusses our recent achievements in this area. Switching system interconnections are classified based on their application layers. The evolution of optical interconnections in switching systems in discussed in terms of such system requirements as cost, size, and throughput. Recent achievements are discussed: an optical inter-module connector, a free-space digital switch, and a large-capacity optically intra-connected ATM switch.