The crosstalk characteristics of a long-wavelength monolithically integrated photoreceiver array are analyzed. The device consists of an array of transimpedance photoreceivers fabricated on a semi-insulating InP substrate. The distance between the photodetectors is large enough to suppress the photonic crosstalk. Therefore, the crosstalk of the device is mainly due to signal propagation from the channels through the power line shared by each channel on the chip. This crosstalk is inevitable to the photoreceiver arrays which employ common power lines. The magnitude of the crosstalk largely depends on the impedance of the power-supply circuit outside the chip. The crosstalk spectrum often has a peak and recess structure. The crosstalk peak at the edge of the operating band-width is due to the resonance characteristic of the transimpedance amplifier. The other peak and recess structures on the spectrum are due to the resonance phenomena of on-chip and off-chip capacitors and inductance on the power-supply line outside the chip. This crosstalk can be reduced by using on-chip bypass capacitance and dumping resistance. However, the resonance due to the capacitance and inductance on the power-supply circuit outside the chip can't be controlled by the on-chip components. Therefore, an optimized design for the power supply circuit outside the chip is also indispensable for suppressing crosstalk.

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.

This paper describes the current situations and future directions of intelligent CAI researches/development in Japan. Then necessity of intelligence in CAIs/Educational systems are thought over corresponding to the model of teaching and the cognitive model of human learning like the situated learning, knowledge construction and so on. Originally, the main aims of ITSs/ICAIs are to tealize the high level environment of individual teaching/learning. So it is the most important to incorporate the intellectual function of teaching into the system. Whatever kinds of teaching purposes ITSs have, they have the quite complex structure which consists of the domain knowledge base (Expert system), student model, the tutoring knowledge base, the powerful human interface, and sophisticated inference engine with plural functions by artificial intelligence technology. In this paper, the technological and educational points of view are discussed, surveyed and summarized based on intelligent teaching functions of ITSs/ICAIs. Moreover, the meaning of new paradigm from ITSs to ILE are mentioned under the new technology of networking and multi-media.

A transmission data format for high-speed optical parallel interconnections is proposed and a 4-channel transmitter and receiver link module operating at up to 1.2 Gb/s per channel is demonstrated. The data format features "Group Multiplexing and Coding." In this scheme, input several tens channels are multiplexed and coded in group into reduced channels, resulting in burst-mode compatible, skew-free transmission, and low power-consumption of a link module. Experiments with fabricated modules comfirm that our data coding in multichannel optical transmission is promising for use in high-speed interconnections in information and switching systems.

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.

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.

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.

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 Spread Spectrum Packet Radio Networks (SS/PRNs), different spreading codes are required for different stations for transmitting packets. Therefore multihop SS/PRNs with a large number of stations would require a large number of codes and hence a large channel bandwidth. In this paper we design a code assignment algorithm which could reduce the number of codes required to about 22%. Further reducing the number of codes is found to cause little throughput degradation. The Coded Tone Sense protocol is designed for using these codes in multihop PRNs. Simulation result shows that in a 80 node network using only 5 spreading codes, the maximum network throughput is about 73% higher than the BTMA protocol.

This paper proposes a high-speed VP bandwidth control scheme for ATM networks that utilizes a distributed control mechanism. First, the characteristics of VPs are compared with those of digital paths in STM networks. A distributed control scheme is adopted for rapid control. The basic elements and the necessary distributed function, the control algorithm, and the message transmission mechanism, are elucidated. The bandwidth alteration time with the proposed algorithm is estimated by considering network element processing and queuing delay. The proposed VP bandwidth control scheme can be applied to both public networks and leased line services. Finally, this paper focuses on its application to leased line services, and discusses the resource reduction effects of the proposed scheme.

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.

For improving the RSA cryptosystem, more desirable conditions on key structures have been intensively studied. Recently, M.J.Wiener presented a cryptanalytic attack on the use of small RSA secret exponents. To be secure against the Wiener's attack, the size of a secret exponent d should be chosen more than one-quarter of the size of the modulus n = pq (in bits). Besides, it is more desirable, in frequent cases, to make the public exponent e as small as possible. However if small d is chosen first, in such case as the digital signature system with smart card, the size of e is inevitably increased to that of n when we use the conventional key generation algorithm. This paper presents a new algorithm, Algorithm I, for generating of the secure RSA keys against Wiener's attack. With Algorithm I, it is possible to choose the smaller sizes of the RSA exponents under certain conditions on key parameters. For example, with Algorithm I, we can construct the RSA keys with the public exponent e of two-thirds and secret exponent d of one-third of the size of modulus n (in bits). Furthermore we present a modified version of Algorithm I, Algorithm II, for generating of the strong RSA keys having the difficulty of factoring n. Finally we analyze the performances of Algorithm I and Algorithm II.

It is recognized in Japan that reformation of the national research institutions is urgently necessary. Present situation and constraints are shown and the action items are discussed.

A new pattern synthesis method for multibeam reflector antennas is described. The Directional Constrained Minimum Power (DCMP) method, which was developed as an adaptive array algorithm, has been applied to reflector antennas with cluster feeds. The main objective of this pattern synthesis is to optimize the excitation distribution of the cluster primary feed in order to reduce the sidelobe level and to attain a high main beam gain. A desired contour beam pattern has also been attained by modifying this method. Furthermore, this paper describes other applications of this method, such as pattern optimization taking account of the frequency characteristics and the change in the radiation pattern due to an antenna pointing system, cross-polarization reduction, and monopulse pattern synthesis for an RF sensor.

In this paper, we present some novel concepts and photonic devices for use in optical interconnects. First, we review the progress of surface emitting lasers while featuring materials and performances including thresholds, power output, RIN, linewidth, and so on. Advanced technology for aiming at spontaneous emission control, photon recycling, polarization control, wavelength tuning, integration etc. will be considered. Then we touch on some other possible devices for optical interconnects. Lastly, we discuss on lightwave subsystems applying these devices and concepts.

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.

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.

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.

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.

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.