An eye-contact technique using a blazed half-transparent mirror (BHM) is developed. This half-transparent mirror (HM) consists of an in-line array of many slanting micro-HMs. We fabricated a prototype system and confirmed the principle of this technique. The resolution of an image reflected by a BHM was simulated to determine how to improve the image quality and the factors degrading the resolution were clarified.

A new kind of optical local area network (LAN), using a demand assign wavelength division multiple access (DA-WDMA) scheme, has been proposed. The proposed LAN consists of two parts; an ordinary standardized LAN and an overlaid network using wavelength division (WD) channels. The proposed network can provide bit-rate independent communication channels on the ordinary LAN without limiting the capacities for the other channels. It also exhibits upgrade possibilities from present standardized networks. An access controller, which consists of software in addition to the ordinary LAN controller, a digital signal processor (DSP) etc., was developed for DA-WDMA control. The network node operation has been demonstrated using guided-wave acousto-optic (AO) mode converters as a tunable wavelength add-drop multiplexer (ADM).

In this paper, we present a unified model for dialogue understanding involving various sorts of ambiguities, such as lexical, syntactic, semantic, and plan ambiguities. This model is able to estimate and revise the most preferable interpretation of utterances as a dialogue progresses. The model's features successfully capture the dynamic nature of dialogue management. The model consists of two main portions: (1) an extension of first-order logic for maintaining multiple interpretations of ambiguous utterances in a dialogue; (2) a device which estimates and revises the most preferable interpretation from among these multiple interpretations. Since the model is logic-based, it provides a good basis for formulating a rational justification of its current interpretation, which is one of the most desirable aspects in generating helpful responses. These features (contained in our model) are extremely useful for interactive dialogue management.

Junction leakage current of trench isolation devices is strongly influenced by trench configuration. The origin of the leakage current is the mechanical stress that is generated by the differential thermal expansion between the Si substrate and the SiO2 filled isolation trench during the isolation forming process. A two-dimensional mechanical stress simulation was used to analyze trench-isolated devices. The simulated distribution and magnitude of stress were found to agree with Raman spectroscopic measurements of actual devices. The stress in the deeper regions between deep trenches is likely to increase greatly as the size of devices diminishes, so it is important to reduce this stress and thus suppress junction leakage current.

The modular and growable photonic ATM switch architecture described in this paper uses both time-division and wavelength-division multiplexing technologies, so the switch capacity can be expanded in both the time and frequency domains. It uses a new implementation of output buffering scheme that overcomes the bottleneck in receiving and storing concurrent ultra fast optical cells. The capacity in one stage of a switch with this architecture can be increased from 32 gigabits per second to several terabits per second in a modular fashion. The proposed switch structure with output channel grouping can greatly reduce the amount of hardware and still guarantee the cell sequence.

We investigated the impact of velocity overshoot effect on collector signal delay of bipolar devices by using Monte Carlo simulation method. We found that insertion of an i-layer (lightly doped, intrinsic layer) between base and collector can increase the delay, but the strength of this effect is a function of the i-layer thickness. When the i-layer becomes thinner, the problem of increasing delay seems to disappear. This recovery of delay is realised with a mechanism which is completely different from that in drift-diffusion model.

We consider a communication system in which a transmitter is connected to a receiver through parallel channels, and the Go-Back-N ARQ scheme is used to handle transmission errors. A packet error on one channel results in retransmission of packets assigned to other channels under the Go-Back-N ARQ scheme. Therefore, the channel-grouping (a grouped-channel is used to transmit the same packet at a time), would affect the throughput performance. We analyze the throughput performance, and give a tree-algorithm to efficiently search for the optimal channel-grouping which makes the throughput to become maximum. Numerical results show that the throughput is largely improved by using the optimal channel-grouping.

This paper describes an implementation of the finite element method to examine the effects of actual lip shape on the sound radiation. A three-dimensional finite element approach by Galerkin method was used. The accuracy of the calculation of finite element method for the sound radiation was tested by comparing it with the exact solutions for a circular piston radiator on an infinite baffle. Using a set of finite element models of the vocal tract, we calculated the responses to a pure tone input and the sound fields over the frequency range of 100 Hz-7 kHz. The transfer functions are examined in detail for vowels /a/ and /i/ when the shape of the actual lips is simplified as a planeradiation surface. The effects of lip shape on the distribution of sound pressures are also shown in both the vocal tract and the surrounding space of the mouth opening.

Among various photonic switching technologies, photonic frequency division multiplexing technology is most promising. In this paper a novel photonic FDM (Frequency Division Multiplexing) system is proposed. The proposed system consists of n (multiplicity of frequencies) independent subnetworks, each of which is identified by a specific frequency, and of which each network topology is identical. When a connection is required by a terminal, the network selects a subnetwork that can afford it, and assigns a frequency representing the selected subnetwork to the terminal. This system eliminates frequency converting devices and traffic concentration equipment, which will reduce the size and cost of the system. A very small sized switching system of very large capacity will be easily realized. In this paper, first we will address the basic concept of the proposed system, and then discuss some technical problems and their solutions concerning network configuration, switch matrix structure, subscriber network configuration, control scheme and frequency multiplicity. Some experimental results are also mentioned.

A Si metal insulator semiconductor tunnel emitter transistor (Si MIS TET) which is a new type of bipolar transistor was fabricated and its electrical properties for the temperature range of 100 K - 300 K were investigated. The common emitter mode current gain obtained was 75 at 300 K and 74 at 100 K. It was confirmed by measuring the temperature dependence of the base current that the inversion base layer indeed functioned as a base of the Si MIS TET. The current gain of the Si MIS TET did not decrease at low temperature of 100 K, though the current gain of the conventional Si bipolar transistor decreases at low temperature due to the emitter bandgap narrowing in heavily doped emitter. This origin was that the carrier injection mechanism between the emitter and the base was tunneling.

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.

The well-known closure tests, the cycling closure test (CCT) and the meet-in-the-middle closure test (MCT), were introduced by Kaliski, Rivest and Sherman to analyze the algebraic properties of cryptosystems, and CCT indicates that DES is not closed. Though Coppersmith presented that DES can be proved not to be closed by a particular way, the closure tests can check various kinds of cryptosystems generally. Thus, successors to MCT and CCT have been proposed at CRYPTO. This paper expands the MCT successor, the switching closure test (SCT), to apply to the DES-like cryptosystems, and shows that this SCT variant is more efficient than the closure test proposed at CRYPTO'92, because the SCT variant establishes a better relationship between the computation cost and the probability of error (the evaluation index). The MCT successors are more important than the CCTs, because the MCTs can directly break closed cryptosystemes. Therefore, if you want to detect the closure property of cryptosystems generally, the SCT variant is better.

Koblitz and Miller proposed a method by which the group of points on an elliptic curve over a finite field can be used for the public key cryptosystems instead of a finite field. To realize signature or identification schemes by a smart card, we need less data size stored in a smart card and less computation amount by it. In this paper, we show how to construct such elliptic curves while keeping security high.

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.

Beam-steering devices are attractive for spatial optical interconnections. Those devices are essential not only for fixed connecting routed optical interconnections, but for flexible connecting routed optical interconnections. The flexible connecting routed optical interconections are more powerful than the conventional fixed connecting routed ones. Structures and characteristics of beam-steering devices, a beam-scanning laser diode and a fringe-shifting laser diode, are reported for those interconnections. Using these lasers, the configurations of several optical interconnections, such as optical buses and optical data switching links as examples of fixed and flexible connecting routed optical interconnections are discussed.

This paper presents a novel model of optical associative memory using an optoelectronic neurochips, which detects and processes a two-dimensional input image at the same time. The original point of this model is that the optoelectronic neurochips allow direct image processing in terms of parallel input/output interface and parallel neural processing. The operation principle is based on the nonlinear transformation of the input image to the corresponding the point attractor of a fully connected neural network. The learning algorithm is the simulated annealing and the energy of the network state is used as its cost function. The computer simulations show its usefulness and that the maximum number of stored images is 150 in the network with 64 neurons. Moreover, we experimentally demonstrate an optical implementation of the model using the optoelectronic neurochip. The chip consists of two-dimensional array of variable sensitivity photodetectors with 8 16 elements. The experimental results shows that 3 images of size 8 8 were successfully stored in the system. In the case of the input image of size 64 64, the estimated processing speed is 100 times higher than that of the conventional optoelectronic neurochips.

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.

This letter proposes a microstrip band elimination filter having an optically controlled small gap on a resonant section for the shift of the eliminated frequency range using the semiconductor plasma. The basic characteristics of this filter are analized theoretically utilizing the (FD)2TD method.

The performances of BPNN (neural network trained by back propagation) and PCANN (neural network which computes principal component analysis) for ECG data compression have been investigated from several points of view. We have compared them with an existing data compression method TOMEK. We used MIT/BIH arrhythmia database as ECG data. Both BPNN and PCANN showed better results than TOMEK. They showed 1.1 to 1.4 times higher compression than TOMEK to achieve the same accuracy of reproduction (13.0% of PRD and 99.0% of CC). While PCANN showed better learning ability than BPNN in simple learning task, BPNN was a little better than PCANN regarding compression rates. Observing the reproduced waveforms, BPNN and PCANN had almost the same performance, and they were superior to TOMEK. The following characteristics were obtained from the experiments. Since PCANN is sensitive to the learning rate, we had to precisely control the learning rate while the learning is in progress. We also found the tendency that PCANN needs larger amount of iteration in learning than BPNN for getting the same performance. PCANN showed better learning ability than BPNN, however, the total learning cost were almost the same between BPNN and PCANN due to the large amount of iteration. We analyzed the connection weight patterns. Since PCANN has a clear mathematical background, its behavior can be explained theoretically. BPNN sometimes generated the connection weights which were similar to the principal components. We supposed that BPNN may occasionally generate those patterns, and performs well while doing that. Finally we concluded as follows. Although the difference of the performances is smal, it was always observed and PCANN never exceeded BPNN. When the ease of analysis or the relation to mathematics is important, PCANN is suitable. It will be useful for the study of the recorded data such as statistics.

This paper describes our recent developments of ASICs for automotive multiplexing and data communications to implement in-vehicle networks. With the advancement of automotive electronics, there are ever growing needs for in-vehicle networks. One need is associated with solving the problem of an increasing number of electrical signal wires that inevitably accompany the increasing applications of automotive electronics. Another kind of need is concerned with sharing vehicle control data among several electronic control units such as engine, brake, suspension, and steering electronic control units to achieve an integrated vehicle control system for the purpose of obtaining higher performances in vehicle dynamics. In order to reduce the number of signal wires and share the control data, in-vehicle networks based on multiplexing and data communications are required. In this paper, two original communication protocols are presented to respectively cover low- and highi-speed multiplexing and data communications that are two most needed communication speed areas in our present and future automobiles. ASICs for the presented communication protoclos were designed and fabricated, using 2 µm COMS process. They have the chip size of 3.2 mm2.7 mm with 5,000 transistors and 6.9 mm4.9 mm with 18,000 transistors respectively for low- and high-speed multiplexing and data communications. An elaborate bus driver/receiver ASIC required for high-speed multiplexing and data communications was also designed and fabricated, using 35 V DC bipolar process. As one of its distinctive features, it can greatly suppress radio frequency noise radiated from a communication bus. It has the chip size of 4.8 mm3.8 mm that contains 570 device elements. The features of the protocols are given in detail with the descriptions of the developed ASICs.