This paper presents a hypermedia English learning environment, called HELEN (Hypermedia Environment for Learning ENglish), which integrates traditional methods of learning English, audio-visual facilities for both listening and watching and intelligent tutoring functions for suitable advice to each learner based on natural language understanding. HELEN consists of an authoring stage and a learning stage. In order to support multimodal learning, at the authoring stage HELEN gets voice and video scenes from a video disc and text sentences from an image scanner, then analyzes the sentences both syntactically and semantically by a natural language processing module so that necessary information for conversation, error identification and example sentence retrieval may be extracted. Thus at the learning stage, HELEN is able to aid learners to learn hearing, reading, writing, watching, consulting and noting. Besides these facilities HELEN also supports two facilities for tests in English: One is the test facilities of dictating sentences and the other is QA (questions and answers) facilities to make learner's comprehension state clear. According to the results of these tests, HELEN identifies learner's illegal usage of syntax or semantics, and piles them in a student model. The illegal usage in the model is used as resources for generating questions, treating errors, determining topics, etc. The main part of this paper concerns with the representation method for syntax and semantics of correct and incorrect sentences.

This paper describes the development of an environmental ICAI system for English conversation learning, which is equipped with a simulation-based learning environment and an advisor function. Recently there have been various educational applications or tools for adult second language education, where the learning target is the acquisition of formal knowledge of a language. When considering the implementation of a practical CAI system, methods for developing communicative competence in learners are required. Although there are a number of ICAI systems for conversation learning, often the methodologies which they apply are not completely suitable for the acquisition of the required fundamental knowledge. Our system, based on the architecture of environmental CAI, enhances communication skill acquisition. The system has a learning environment with the following features: (1) A simulation of language activities, implemented in the role-playing game style, which helps to promote a learner's motivation. (2) Educational behavior of the system is varied through the modification of the learning environment and changes in the simulation progress and control commands. (3) An induction strategy, which can cause learners to fail to achieve a learning target, is executed by an advisor mechanism. The system is a prototype architecture for application in environmental ICAI systems for simulation based learning. We believe that the architecture of this system is an efficient framework for linguistic education.

The learning environment called IPE (Interactive Physical Environment) for Dynamics is developed on the computer. IPE can understand the simulated phenomena started from the arbitrary conditions set up by the learner. IPE has several scripts which describe the dynamical phenomena. The understanding of the simulated phenomena by IPE is obtained by matching these scripts with status list and phenomena list which are generated by the simulator using difference scheme. IPE gives the learner the explanation sentences which explain the features of simulated phenomena. This explanation strongly assist the learner in recognizing the details of result of the simulation.

This paper considers the subliminal channel, hidden in an identification scheme, for transferring signatures. We observe the direct parallelization of the Fiat-Shamir identification scheme has a subliminal channel for the transmission of the digital signature. A positive aspect of this hidden channel supplies us how to transfer signatures without secure channels. As a formulation of such application, we introduce a new notion called privately recordable signature. The privately recordable signature is generated in an interactive protocol between a signer and a verifier, and only the verifier can keep the signatures although no third adversary can record the signatures. ln this scheme, then the disclosure of the verifier's private coin turns the signer's signature into the ordinary digital signature which is verified by anybody with the singer's public key. The basic idea of our construction suggests the novel primitive that a transferring securely signatures without secret channels could be constructed using only one-way function (without trapdoor).

This paper presents an experimental environment of an intelligent tutoring system called EXPITS. In this environment, users learn functions and the structure of the intelligent tutoring system and characteristics of knowledge processing. EXPITS provides facilities for investigating internal processes and internal states of the intelligent tutoring system. These facilities include visualization tools and controllers of internal processes. Because the internal states and behavior of ITS depend on student's understanding states, one cannot get total understanding of ITS without information about student's knowledge states. To solve this problem, we introduce a pseudo student which simulates a human student in order to visualize explicitly all information which affects ITS behavior. Target users of EXPITS are school teachers, who are users of intelligent tutoring systems, university students who are studying artificial intelligence and postgraduate students who are specially studying intelligent tutoring systems. We have designed EXPITS to achieve different learning objectives for these three kinds of users. The learning objective for school teachers is to understand the differnce between intelligent tutoring systems and traditional CAI systems. University students are expected to understand characteristics of knowledge processing and rule based systems. Lastly, EXPITS provides postgraduate students who are studying intelligent tutoring systems with a test bed for examining ability and efficiency of the system in different configurations by changing parameters and by replacing constituents of the system. To achieve these purposes, EXPITS has experimental facilities for the following four themes; relationship between the domain knowledge representation method and teaching activities, the selection method of teaching paradigms, relationship between problem solving processes and teaching activities, and student modeling.

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.

In 1963, the authors began to develop a tuning circuit (hereafter referred to as the 'circuit') consisting of an inductor, fixed capacitors and a variable capacitor. The circuit required very high accuracy and stability, and the aging influence on resonant frequency needed to be Δf/f0 0.12% for 20 years. When we started, there was no methodology available for designing such a long-term stable circuit, so we reinvestigated our previous studies concerning aging characteristics and formed a design concept. We designed the circuit by bearing in mind that an inductor was subject to natural and stress demagnetization (as indicated by disaccommodation), and assumed that a capacitor changed its characteristics linearly over a logarithmic scale of time. (This assumption was based on short-term test results derived from previous studies.) We measured the aging characteristics of the circuits at room temperature for 20 years, from 1966. The measurement results from the 20-year study revealed that the aging characteristics predicted by the design concept were reasonably accurate.

An efficient algorithm is presented for finding all solutions of piecewise-linear resistive circuits. In this algorithm, a simple sign test is performed to eliminate many linear regions that do not contain a solution. This makes the number of simultaneous linear equations to be solved much smaller. This test, in its original form, is applied to each linear region; but this is time-consuming because the number of linear regions is generally very large. In this paper, it is shown that the sign test can be applied to super-regions consisting of adjacent linear regions. Therefore, many linear regions are discarded at the same time, and the computational efficiency of the algorithm is substantially improved. The branch-and-bound method is used in applying the sign test to super-regions. Some numerical examples are given, and it is shown that all solutions are computed very rapidly. The proposed algorithm is simple, efficient, and can be easily programmed.

This letter deals with the reliability function in the case of periodic preventive replacement of items in order to increase MTBF, that is, two replacement policies; strictly periodic replacement (SPR) and randomly periodic replacement (RPR). We stress on simple introduction of the reliability theory under preventive replacement policies using the Laplace transform and obtain the theoretical results of SPR and RPR. Then these results are applied to the Weibull distribution and finally in order to show useful information of preventive replacement, the numerical results of SPR are provided.

Optical waveguides are one of the key devices for photonic integrated circuits considered to be one of the candidates for optical interconnects. In particular lossless bend type waveguides are necessary to integrate different optical devices monolithically. In this paper, we report on the bending loss characteristics of the multi-quantum well bend waveguide with respect to the bend radius and lateral optical mode confinement. We show that to decrease the bending loss to less than 0.5 dB, it is necessary to increase either the confinement or the bend radius. For an example, when the confinement is around 85%, the bend radius should be more than 2 mm. We also show the application of the S-bend waveguides to directional coupler type optical switch.

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.

Kanji Laboratory is a kanji learning ICAI system. In this paper, we describe the development of Kanji Laboratory, which is designed for foreigners who are learning Japanese kanji. We have developed Kanji Laboratory under the guidelines of environmental ICAI systems, based on a kanji learning method focusing on kanji radicals. Kanji Laboratory consists of a knowledge base, a learning environment and an advisor module. The knowledge base can well-handle the knowledge of Joyo Kanji (1,945 characters). Each one is related with its radicals via their inherited attributes. In addition, this knowledge base system can search kanji knowledge quickly. The learning environment has the following features: (1) Students can construct a kanji by combining radicals and disassemble the kanji into radicals and strokes. (2) Students can use electronic tools, such as a kanji dictionary, which support kanji learning. In this way, students can learn kanji and the relations with its radicals effectively. With regard to the advisor, although it occurs that students fall in plateaus of learning in environmental CAI, the advisor module is designed to give well-timed advice to students, avoiding those plateaus, based on the observation of their learning actions.

Electronics and automobiles were bound together by the introduction of emission regulations in the 1970's. The rapid progress of control technology and semiconductors that typify microcomputers has brought still closer relations between them. Without electronics, it would be impossible to realize features such as pursuit of comfort and environmental and safety measures which should be added to the automobile's fundamental features. In looking ahead to the future, the role of electronics in achieving electric automobiles and the ultimate goal of "automatic driving" is ever-increasing. Everyone knows that automobiles have become indispensable in our lives. In the future, the role of electronics will become increasingly important in order to evolve automobiles even further to allow harmonization with society.

This paper presents an equation capable of briefly evaluating the length of white noise sequence to be sent as a training signal. The equation is formulated by utilizing the formula describing the convergence property, which has been derived from the IIR filter expression of the NLMS algorithm. The result revealed that the length is directly proportional to I/[K(2-K)] where K is a step gain and I is the number of the adaptive filter taps.

MultiWave data compression algorithm is based on the multiresolution wavelet techniqu for decomposing Electrocardiogram (ECG) signals into their coarse and successively more detailed components. At each successive resolution, or scale, the data are convolved with appropriate filters and then the alternate samples are discarded. This procedure results in a data compression rate that increased on a dyadic scale with successive wavelet resolutions. ECG signals recorded from patients with normal sinus rhythm, supraventricular tachycardia, and ventriular tachycardia are analyzed. The data compression rates and the percentage distortion levels at each resolution are obtained. The performance of the MultiWave data compression algorithm is shown to be superior to another algorithm (the Turning Point algorithm) that also carries out data reduction on a dyadic scale.

Two types of circuit architecture for GaAs LSI are described. The first circuit is named Stacked DCFL which has supply voltage compatibility with Si CMOS/BiCMOS and ECL operating on 3 V or 3.3 V. A divide by 128/129 prescaler IC has been developed to confirm the Stacked DCFL circuit operation. The second circuit is named SVFL which operates on single supply voltage by using Schottky FET characteristics in spite of normally-on FET logic. Both circuit architectures are based on the virtual ground concept. The transition time of 45 psec was obtained by the SVFL ring oscillator circuit fabricated with 1 µm gate length FET process, and the transition time of DCFL using the same process was from 80 psec to 100 psec. Stacked DCFL and SVFL are candidates for an internal gate and an input/output interface circuit for GaAs ASIC, respectively.

A communication LSI Set for Automotive Body control systems such as power windows, power seats, and power doors based on an in-vehicle network have been developed. The main function of the LSI is to achieve an original automotive communication protocol. The LSI set makes it possible to build a new kind of automotive control system, and reduces the number of wiring harnesses and weight below those of the conventional automotive body electronics. The communications transmitters and receivers have been integrated on-chip, so the LSI needs several external discrete components such as resistors, capacitors, and diodes. This communications LSI offers the advantages of small size and high reliability of the electronic control unit based on an in-vehicle network.

An omnidirectional microstrip antenna using a parasitic cylinder is presented. A rectangular patch is formed on a dielectric substrate and it's completely covered with an aluminum cylinder which is somewhat shorter than a half of free space wavelength. Under such configuration the aluminum cylinder works as a parasitic element. This antenna can provides uniform omnidirectional radiation patterns and a broad frequency bandwidth. In this paper an experimental method for designing such an element is described. Measured input impedance characteristics, current distribution around the surface of the cylinder and patterns are also shown. By properly adjusting the coupling intensity between the patch and the parasitic cylinder a broad bandwidth antenna element can be realized. Some methods to adjust the coupling intensity are shown. A wide bandwidth element up to 14% for VSWR1.5 is obtained. Arranging many patches lengthways on a substrate and placing metallic cylinders around each patches, we can realize a high-gain and broad bandwidth collinear antenna.

A full-wave analysis for the scattering problem of infinite periodic arrays on dielectric substrates excited by a circularly-polarized incident wave is presented. The impedance boundary condition is solved by using the moment method in the spectral domain. Numerical results are given and scattering properties are discussed.

A rectenna element applicable to Stratosphere Radio Relay System was proposed and a fundamental microwave power transmission experiment was carried out at 2.45GHz using a rectenna array manufactured based on the proposal. The rectenna element consists of a circular microstrip patch and a rectifying circuit of novel balanced-type design. The circuit allows to mount a rectifier and circuit components just on one side of a substrate without through holes, and hence it must be easy to manufacture a rectenna even having a large aperture. It was verified by a preliminary experiment that the rectifying circuit can provide more than 1 W of DC output power using 8 Shottky diodes as a rectifier with microwave-DC conversion efficiency of 67%. Then, DC output power of 4W was obtained from the 4-element rectenna array in the microwave power transmission experiment carried out in a radio anechoic chamber. The data showed a feasibility of practical application of the microwave power transmission technique.