The power transfer characteristics of a symmetric nonlinear directional coupler (NLDC) are analyzed rigorously using the beam propagation method based on the finite difference scheme. The NLDC consists of two linear waveguides separated by a Kerr-like nonlinear gap layer. The change of nonlinear refractive index along the coupler is precisely evaluated by making use of the second-order iteration procedure with respect to a small propagation length. For the incidence of TE0 mode of the isolated linear waveguide, the highly accurate numerical results are obtained for the behavior of power transfer, and the coupling length and critical power for optical switching. The dependencies of the coupling length and critical power on the width of the gap layer and the input power levels are discussed, compared with those predicted by the coupled-mode approximations.

Numerical simulation of the hydrodynamic semiconductor device equations requires powerful numerical schemes. A Space-time Galerkin/Least-Squares finite element formulation, that has been successfully applied to problems of fluid dynamic, is proposed for the solution of the hydrodynamic device equations. Similarity between the equations of fluid dynamic and semiconductor devices is discussed. The robustness and accuracy of the numerical scheme are demonstrated with the example of a single electron carrier submicron silicon MESFET device.

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.

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.

The relation between the radiation pattern and the dimension of the conducting box for a portable telephone is illustrated both theoretically and experimentally. The Galerkin-moment method using the Fourier series expansion for the surface current of the conducting box, which has a great advantage of having a high accuracy, is employed to obtain the radiation pattern. As an example of antennas, a quarter-wavelength monopole antenna having a sinusoidal current distribution is used. As a result, it is pointed out that the radiation pattern of a monopole antenna mounted on the box tends to tilt in a lower direction both in theory and in experiment as well. The relation between the radiation pattern and the location of the monopole antenna is also described. An asymmetrical, or distorted pattern is observed when the monopole antenna moves away from the center of the top plane.

It was more than 10 years ago that the first map navigation system, as an example of invehicle information system, has appeared in the market in Japan. Today's navigation system has been improved to the level that the latest system has 10 micro-processors, 7 MBytes of memories, and 4 GBytes of external data storage for map database. From the viewpoint of the automobile driver, there are still some problems with the system. Major problems in general are a lack of traffic information, better human interface, and a need for cost-reduction. The introduction of application specific ICs (ASICs) is expected to make systems smaller, costless, and give higher speed response. Today's in-vehicle information systems are reviewed function by function to discover what functions need to be implemented into ASICs for future systems, what ASICs will be required, and what technology has to be developed. It is concluded that more integration technology is expected including high parformance CPUs, large capacity memories, interface circuits, and some analog circuits such as DA converter. To develop this technology, some, major problems such as power consumption, number of input/output signals, as well as design aid and process technology are pointed out.

A theoretical and experimental study of a thin card-sized antenna is presented. The method of moment with a wire-grid model is used to analyze this antenna. In order to validate numerical efficiency, measurements using Wheeler method are preformed on this antenna and its wire-grid models. The experimental and theoretical results are in good agreement if the wire conductivity is well chosen. And the noise reduction of measured Wheeler efficiency using least mean square method is also examined.

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.

The emerging discipline of responsive systems demands fault-tolerant and real-time performance in uniprocessor, parallel, and distributed computing environments. The new proposal for responsiveness measure is presented, followed by an introduction of a model for responsive computing. The model, called CONCORDS (CONsensus/COmputation for Responsive Distributed Systems), is based on the integration of various forms of consensus and computation (progress or recovery). The consensus tasks include clock synchronization, diagnosis, checkpointing scheduling and resource allocation.

This paper proposes a group-to-group communications algorithm that can extend the range of distributed systems where we can achieve active replication fault-tolerance to partner model distributed systems, in which all processes communicate with each other on an equal footing. Active replication approach, in which all replicated processes are active, can achieve fault-tolerance with low overhead because checkhpoint setting and rollback are not required for recovery from process failure. This algorithm guarantees that each replicated process in a process group has the same execution history and that communications between process groups keeps consistency even in the presence of process failure and message loss. The number of control messages that must be transmitted between processes for a communication between process groups is only a linear order of the number of replicated processes in each process group. Furthemore, this algorithm reduces the overhead for reconfiguration of a process group by keeping process failure and recovery information local to each process group.

In this paper the two different paradigms for the design of responsive, i.e., distributed fault-tolerant real-time systems, the event-triggered (ET) approach and the time-triggered (TT) approach, are analyzed and compared. The comparison focuses on the temporal properties and considers the issues of predictability, testability, resource utilization, extensibility, and assumption coverage.

This paper proposes a reconfigurable parallel processor based on a two-dimensional linear celular automaton model. The processor based on the model can be reconfigured quickly by utilizing the characteristics of the automaton used for its model. Moreover, the processor has short data path length between processing elements compared with the length of the processor based on one-dimensional linear cellular automaton model which has been already discussed. The processing elements of the processor based on the two-dimensional linear cellular automaton model are regarded as cells and the operational states of the processor are treated as the states of the automaton. When faults are detected, the processor can be reconfigured by changing its state under the state transition function of the processor determined by the weighting function of the automaton model. The processor can be reconfigured within a clock period required for making a state transition. This processor is extremely effective for real-time data processing systems required high reliability.

A multi-beam airborne pulsed-Doppler radar (MBR) system is presented and its clutter rejection performance compared with conventional phased array radar (PAR)'s by PRF tuning is discussed. The pulsed-Doppler radar equations taking account of the multi-beam operation are introduced and some kinds of computer simulations for seeking the conditions to get maximum signal to clutter ratio are carried out. As a results of this, it is cleared that same order of signal to clutter ratio improvement gotten in high PRF operation by conventional PAR can be realized at lower PRF operation by MBR on clutter free area, and higher clutter rejection effect, which is proportional to beam numbers, is obtained under affection of both of mainlobe and sidelobe clutters with order of beam numbers. This also means observable numbers of range bin are increased in MBR operation.

We describe K-NET, a support system for development of sequence control programs. The K-NET description model is based on the colored Petri net and timed Petri net. K-NET concisely expresses sequence control flow including synchronization, interlock and concurrence, and provides high-level data processing by being combined with a conventional procedural language. K-NET has an editor, simulator, generator, reporter and monitor to support the control program development procedure ranging from basic and detail design to programming and testing. We have added a new function to K-NET so it assists development of control programs for programmable controllers, and have applied it to an automatic bolt supplying system. The operation results are satisfactory.

A wavelength-insensitive reflector is demonstrated with a fibre loop which has an asymmetry in the constituent coupler. The reflector is made by thinning one of two identical fibres. The reflected power is more than 0.6 dB (87%) over the wavelength region of 1.2-1.35 µm and 1.42-1.65 µm. The transmitted power is less than 30 dB in the 1.23-1.63 µm region and less than 40 dB at 1.3 and 1.55 µm.

A method to measure the displacement from the phase rotation of the Doppler signal including the displacement information of the moving body is proposed, where the displacement resolution can be improved 4 times by making the phase rotation faster. Furthermore, this test system is applied in clinical use. The test system is built up by using a two-phase microwave Doppler sensor covering a 10GHz band, where the Doppler frequency is multiplied 4 times by signal processing. Thus, the resolution is improved from a conventional 12.6mm (in case of 11.9GHz) to 3.15mm, and practical utilization has been attained. The microwave Doppler radar system described in this paper is adequate for the displacement measurement for a relatively fast moving body. As a medical sensor for clinical use, measurement examples of head movement in a vestibule examination (vestibule oculomotor reflexive inspection) and finger movement in a cerebellum function test are given. Furthermore by using two sets of this Doppler radar system, a 2-dimensional measurement of head movement is possible.

A modern architect can not design high performance computer architecture without thinking all factors of performance from hardware level (logic/layout design) to system level (application programs, operating systems, and compilers). For computer architecture design, there are few practical CAD tools, which support design activities of the architect. In this paper, we propose a CAD tool, called COACH, for computer architecture design. COACH supports architecture design from hardware level to system level. To make a high-performance general purpose computer system, the architect evaluates system performance as well as hardware level performance. To evaluate hardware level performance accurately, logic/layout synthesis tools and simulator are used for evaluation. Logic/layout synthesis tools translate the architecture design into logic circuits and layout pattern and simulator is used to get accurate information on hardware level performance which consists of clock frequency, the number of transistors, power consumption, and so on. To evaluate system level performance, a compiler generator is introducd. The compiler generator generates a compiler of a programming language from the desripition of architecture design. The designed architecture is simulated in the behavior level with programs compiled by the compiler, and the architect can get information on system level performance which consists of program execution steps, etc. From both hardware level performance and system level performance, the architect can evaluate and revise his/her architecture, considering the architecture from hardware level to system level. In this paper, we propose a new design methodology which uses () logic/layout synthesis tools and simulators as tools for architecture design and () a compiler generator for system level evaluation. COACH, a CAD system based on the methodology, is discussed and a prototype of COACH is implemented. Using the design methodology, two processors are designed. The result of the designs shows that the proposed design methodology are effective in architecture design.

This paper presents a Reconfigurable Machine (RM). capable of efficiently implementing a wide range of computationlly complex algorithms. Its highly flexble architecture combining FPGA's with RAM's supports a wide range of applications. Since its "gate-level programmability" allows us to implement various kinds of parallel processing techniques, RM provides a perfomance comparable to exising "special-purpose" engines. The in-circuit reconfiguration capability of FPGA's is used to reload several kinds of configuration data during power on. Thus, RM behaves itself like a general-purpose computer applicable to various kinds of applications by loading programs. A Reconfigurable Machine-(RM-) has been built as the first prototype incorporating five FPGA's and four SRAM memory banks. RM- has been applied to a multiple-delay Logic Simulator (LSIM). Employing pipeline architecture, LSIM has achieved a perfomance of l million gate events per second at 4MHz. The concept of RM is the best solution to the trade-offs between general-purpose machines and special-purpose ones. RM will be a hardware platform accelerating a wide range of applications, also offering an interesting problem in high-level synthesis.

A linear block code has a finite-length trellis diagram which terminates at the length of the code. Such a trellis diagram is expressed and constructed in terms of sections. The complexity of an L-section trellis diagram for a linear block code is measured by the state and branch complexities, the state connectivity, and the parallel structure. The state complexity is defined as the number of states at the end of each section of the L-section trellis diagram, the branch complexity is defined as the number of parallel branches between two adjacent states, the state connectivity is defined in terms of the number of states which are adjacent to and from a given state and the connections between disjoint subsets of states, and the parallel structure is expressed in terms of the number of parallel sub-trellis diagrams without cross connections between them. This paper investigates the branch complexity, the state connectivity, and the parallel structure of an L-section minimal trellis diagram for a binary linear block code. First these complexities and structure are expressed in terms of the dimensions of specific subcodes of the given code. Then, the complexities of 2i-section minimal trellis diagrams for Reed-Muller codes are given.

Properties of a strongly-coupled nonlinear directional coupler (NLDC) with a lossy MQW coupling layer is analyzed using the Galerkin finite element method accompanied by a predictor-corrector algorithm. It is shown that the propagation attenuation along the NLDC is considerably smaller than that in the bulk MQW and tends to reduce with the input power. By the presence of losses, the powers guided in two waveguides do not become a maximum and a minimum at the same propagation length, unlike the lossless coupler. The losses make the nonlinear effect weak due to the decrease in guided power, and hence the coupling length decreases and the switching power increases. The extinction ratio of the switching becomes the largest value not in the cases of nonloss and high losses but in the case of moderately high losses, although the switching power is somewhat larger than that of the lossless case.