In the spatial network method (SNM) for the vector potential, both the current continuity law including polarization vector and the conservation law of generalized momentum including vector potential field can introduce simpler expressions for dispersive property than that by the electromagnetic field variables. But for the anisotropic medium conditions, the conventional expanded node expression has some difficulties in treating the coupling mechanism among field variables. On the other hand, in the condensed node expression, in which all field components exist at each node, every connections among field components can be simply formulated. In this paper, after proposing the condensed node spatial network method for the vector potential, the advantage of the method such as performing the simplified formulation by utilization of both the vector potential and the condensed node expressions is presented for the magnetized plasma which has the gyro-anisotropy. The validity of the computation is shown by some examples such as Faraday rotation.

A thin-film waveguide amplifier based on Er-doped Garnet crystals is proposed and transient amplification characteristics, studied numerically using time-dependent rate equations and mode evolution equations, are presented. The potential of the amplifier for integration with active devices operating at the present communication wavelength of 1. 53 µm band is revealed. Pump wavelengths in the visible and near infrared lead to excited state absorption, and will affect the gain characteristics, which has been included in the present study. Steady state response of the Er doped Garnet crystal waveguide amplifiers has been analyzed in order to optimize the gain characteristics, which are further used in the dynamic response analysis. Accordingly, it is shown that a high gain of 20 dB/cm is possible to be achieved. Experimentally determined parameters such as waveguide loss, absorption and emission cross-sections have been used for the simulations. Comparisons of the present simulation results with our earlier reported results of quasi-two-level laser model and other reported results are also presented. Understanding the dynamic characteristics of the integrated optic waveguide amplifiers is necessary when the input signal is modulated in various formats. Because of the slower gain dynamics of the Er doped Garnet amplifier medium, it is shown that the longer signal input pulses are observed to be distorted upon amplification. Very short single pulse of nano- and pico-second duration are amplified without change in the pulse shape. Input pulses of square, Gaussian and Lorentzian shapes have been considered for the numerical examples.

The equivalence between Aperture Field Integration Method (AFIM) and Physical Optical (PO) is discussed for polyhedron surfaces in this paper. The necessary conditions for the equivalence are summarized which demand complete equivalent surface currents and complete apertures. The importance of the exact expressions for both incident and reflected fields in constructing equivalent surface currents is emphasized and demonstrated numerically. The fields from reflected components on additional surface which lies on the Geometrical Optics (GO) reflection boundary are evaluated asymptotically. The analytical expression enhances the computational efficiency of the complete AFIM. The equivalent edge currents (EECs) for AFIM (AFIMEECs) are used to extract the mechanism of this equivalence between AFIM and PO.

This paper discusses a method to evaluate mutual couplings of cavity-backed slot antennas using the FDTD technique. The antenna fed by the short-ended probe is considered, which is investigated as an element of the power transmission antenna, Spacetenna, for the solar power satellite SPS2000. It is found from the FDTD computation on E-plane two- and four-element array antennas that the size of the problem space should be larger for the evaluation of the mutual coupling than for the estimation of the input impedance. Since enlarging the size of the problem space requires a large amount of computer storage, it is not practical for computer simulations. In order to carry out accurate estimations of the mutual coupling with relatively small amount of computer memory, the problem space is extended only in the broadside of the array antenna and in the other directions there are ten cells between the antenna surface and the outer boundary. Computer simulations demonstrate that there are no differences between the results of the proposed problem space geometry and the problem space extended in each direction of the axis coordinate by the same number of cells. Furthermore comparisons of computed and experimental results demonstrate the effectiveness of the approach after discussing how large the size of the problem space is required to estimate the mutual coupling.

This paper presents a new compound constructive algorithm of neural networks whereby the fuzzy logic technique is explored as an efficient learning algorithm to implement an optimal network construction from an initial simple 3-layer network while the genetic algorithm is used to help design an improved network by evolutions. Numerical simulations on artificial life demonstrate that compared with the existing network design algorithms such as the constructive algorithms, the pruning algorithms and the fixed, static architecture algorithm, the present algorithm, called FuzGa, is efficient in both time complexity and network performance. The improved time complexity comes from the sufficiently small 3 layer design of neural networks and the genetic algorithm adopted partly because the relatively small number of layers facilitates an utilization of an efficient steepest descent method in narrowing down the solution space of fuzzy logic and partly because trappings into local minima can be avoided by genetic algorithm, contributing to considerable saving in time in the processing of network learning and connection. Compared with 54. 8 minutes of MLPs with 65 hidden neurons, 63. 1 minutes of FlexNet or 96. 0 minutes of Pruning, our simulation results on artificial life show that the CPU time of the present method reaching the target fitness value of 100 food elements eaten for the present FuzGa has improved to 42. 3 minutes by SUN's SPARCstation-10 of SuperSPARC 40 MHz machine for example. The role of hidden neurons is elucidated in improving the performance level of the neural networks of the various schemes developed for artificial life applications. The effect of population size on the performance level of the present FuzGa is also elucidated.

This paper discusses the experimental evaluation of the knowledge-based program understander ALPUS and methods of program normalization based on the evaluation to improve the flexibility of the system performance. ALPUS comprehends students' buggy Pascal programs using four kinds of programming knowledge, detects logical bugs, infers user's intentions and gives advice for fixing bugs. By means of the combination of the pattern matching technique and the HPG-based formalism of programming knowledge in addition to program normalization high performance of comprehension has been achieved for relatively complex programs such as Quicksort programs. The experimental evaluation told that program normalization would solve some 55% of unsucceeded student programs. Program normalization has contributed both in decreasing the number of knowledge patterns and increasing the flexibility. This paper proposes a five-step normalization procedure which works well in an experimental situation.

For the improvement of software quality and productivity, the author aims at realizing a software development environment to develop software through utilizing the merits of group work. Since networking is necessary for collaborative software development, he has developed a software distributed development environment for collaborative software development. In this environment, discussions about software design are held through a communication network, and the contents of discussions are recorded as software design decisions and decision rationale. One feature of this environment is that the contents of discussions can be recorded in on-line real time and reused without reconstructing the information recorded through this environment. This paper clarifies the essential conditions for actualizing this environment and proposes an information structure model for recording the contents of discussions that actualizes the above-mentioned feature. The effectiveness of the proposed model is proved through an example of its application to software design discussions.

In this paper, we analyze the inverse scattering problem by a new deterministic method called "Source and Radiation Field Solution," which has the merit that both the source and the radiation field can be treated at the same time, the effect of which has already shown in ordinary scattering problems.

This paper presents a new binding algorithm for a retargetable compiler which can deal with diverse architectures of application specific embedded processors. The architectural diversity includes a "non-orthogonal" datapath configuration where all the registers are not equally accessible by all the functional units. Under this assumption, binding becomes a hard task because inadvertent assignment of an operation to a functional unit may rule out possible assignment of other operations due to unreachability among datapath resources. We propose a new BDD-based algorithm to solve this problem. While most of the conventional methods are based on the covering of expression trees obtained by decomposing DFGs, our algorithm works directly on the DFGs so as to avoid infeasible bindings. In the experiments, a feasible binding which satisfies the reachability is found or the deficiency of datapath is detected within a few seconds.

The field profile and effective index of a rib waveguide are calculated using an improved semivectorial beam-propagation method using the imaginary-distance procedure. Convergence behavior of the effective index is compared with that obtained by the conventional Crank-Nicholson scheme and with that derived from a Bierwirth-type formula, demonstrating the effectiveness of the present method. Field discontinuities at the interface between different materials are clearly displayed.

In this paper, we propose a test methodology for core-based system LSIs. Our test methodology aims to decrease testing time for core-based system LSIs. In our method, every core is supplied with several sets of test vectors. Every set of test vectors guarantees sufficient fault coverage. Each set of test vectors consists of two parts. One is based on built-in self-test (BIST) and the other is based on external testing. These sets of test vectors are designed to have different ratio of BIST to external testing each other for every core. We can minimize testing time for core-based system LSIs by selecting from the given sets of test vectors for each core. The main contributions of this paper are summarized as follows. (i) BIST is efficiently combined with external testing to relax the limitation of the external primary inputs and outputs. (ii) External testing for one of cores and BISTs for the others are performed in parallel to reduce the total testing time. (iii) The testing time minimization problem for core-based system LSIs is formulated as a combinatorial optimization problem to select the optimal set of test vectors from given sets of test vectors for each core.

In this paper, we propose a new register transfer level (RT level) testability analysis method. Controllability and observability measures are defined for signal vectors based on the numbers of values they can take. The control part and the datapath part are automatically identified in the given RT level model and distinctive analysis methods are applied. We also describe a DFT point selection method based on our testability measures. In a experiment on a signal processing circuit whose gate count is 7690 including 578 FFs, almost the same fault coverage is achieved with fewer scan FFs than a conventional method based on gate level testability analysis.

This paper presents a new efficient method for finding an "optimal" bi-decomposition form of a logic function. A bi-decomposition form of a logic function is the form: f(X) = α(g1(X1), g2(X2)). We call a bi-decomposition form optimal when the total number of variables in X1 and X2 is the smallest among all bi-decomposition forms of f. This meaning of optimal is adequate especially for the synthesis of LUT (Look-Up Table) networks where the number of function inputs is important for the implementation. In our method, we consider only two bi-decomposition forms; (g1 g2) and (g1 g2). We can easily find all the other types of bi-decomposition forms from the above two decomposition forms. Our method efficiently finds one of the existing optimal bi-decomposition forms based on a branch-and-bound algorithm. Moreover, our method can also decompose incompletely specified functions. Experimental results show that we can construct better networks by using optimal bi-decompositions than by using conventional decompositions.

With the introduction of ATM technology, service providers around the world have actively engaged in offering high bandwidth services. Currently, services, such as T1/E1, T3/E3 circuit emulation, are made available to large-volume account users. However, more advanced services, such as multimedia applications, have demanded not just high bandwidth but also flexible rate adaptation with quality-of-service (QoS) guarantee. To support the above service requirements, sophisticated network planning and engineering procedures should be taken. In the past few years, we have conducted various researches on developing the engineering strategies for resource control and management to support multi-rate service offering. We have also looked into the design details of connection control and management for achieving the QoS requirement. We considered the service quality of the underlying transport in regard with the QoS management. In this paper, we will outline those results and give an overview description about the proposed framework.

This paper proposes a method to reduce the context switching time using a register bank to store contexts of working tasks. Hardware cost and performance were measured by modeling the register bank and controller in VHDL. Following results were obtained: (1) The controller can be implemented with a much smaller amount of hardware cost compared to that of the register bank, which is realized by SRAM module. (2) Context switching time can be reduced to less than 50% compared to that by software implementation. (3) Combination of the proposed architecture with our previous work (RTOS implemented in HW) gives us much higher performance of a hard real-time system.

A novel zero-voltage-switched half-bridge converter is proposed. This converter achieves the zero-voltage switching while maintaining a constant frequency PWM control. Then the power conversion of high efficiency and low noise is realized at a higher switching frequency. In the experiment, a high efficiency of 83% is achieved for a low output voltage of 3.3 V, an output current of 30 A, and an input-voltage range of 200 to 400 V at the switching frequency of 400 kHz.

This paper introduces a new kind of false path, which is sensitizable but does not affect the decision of the maximum clock frequency. Such false paths exist in multi-clock operations controlled by waiting states, and the delay time of these paths can be greater than the clock period. This paper proposes a method to detect these waiting false paths based on the symbolic state traversal. In this method, the maximum allowable clock cycle of each path is computed using update cycles of each register.

A method of visualization of multimodal images by one monochromatic image is presented on the basis of the projection pursuit approach of the inverse process of the anisotropic diffusion which is a method of image restoration enhancing contrasts at edges. The extension of the projection from a linear one to nonlinear sigmoidal functions enhances the contrast further. The deterministic annealing technique is also incorporated into the optimization process for improving the contrast enhancement ability of the projection. An application of this method to a pair of MRI images of brains reveals its promising performance of superior visualization of tissues.

This paper explores virtual destination (VD)/virtual source (VS)-based available bit rate (ABR) flow control performance, targeting wireless asynchronous transfer mode (WATM) application that can incur long link-delays because of employing radio-medium sharing and/or radio-specific data link control schemes. As this paper reveals, the conventional VD/VS scheme has difficulty in sustaining satisfactory ABR performance, when it is applied to long-delay-causing WATM; it suffers from significant increase in the necessary buffer capacity. To ensure the ABR performance in WATM, this paper proposes a new VD/VS coupling scheme using a feed-forward congestion indication. The proposed scheme controls the allowed cell rate of a source end system in a feed-forward manner by predicting the queue length at the time the WATM-associated-round-trip ahead. Simulation results show that the proposed scheme exhibits excellent ABR performance with a long delay of the divided loop on the radio-link side. It is also verified that the proposed scheme is rather robust against uncertainty and/or time-variation regarding the predetermined radio link delay.

In this paper, we represent a class structure using directed graph in which each node corresponds to each member of the class. To quantify the dependence relationship among members, we define weighted closure. Using this quantified relationship and effort equation proposed by M. H. Halstead, we propose a metric for class structural complexity.