In the conventional protocol synthesis, it is generally assumed that primitives in service specifications cannot be executed simultaneously at different Service Access Points (SAPs). Thus if some primitives are executed concurrently, then protocol errors of unspecified receptions occur. In this paper, we try to extend a class of service specifications from which protocol specifications are synthesized by the previous methods. We first introduce priorities into primitives in protocol specification so that it always selects exactly one primitive of the highest priority from a set of primitives that can be executed simultaneously, and executes it. Then, based on this execution ordering, we propose a new protocol synthesis method which can avoid protocol errors due to message collisions, communication competitions and so on. By applying the proposed synthesis method, we can automatically synthesize a protocol specifications from a given service specification which includes an arbitraty number of processes and allows parallel execution of primitives.

In a distributed system, the protocol entities must exchange some data values and synchronization messages in order to ensure the temporal ordering of the events described in a service specification for the distributed system. It is desirable that a correct protocol specification can be derived automatically from a given service specification. In this paper, we propose an algorithm which synthesizes automatically a correct protocol specification from a service specification described as a Marked Graph with Registers (MGR) model and resources (registers and gates) allocation information. This model has a finite control modeled as a marked graph. Therefore, parallel events can be described. In our method, to minimize the number of the exchanged messages, we use a procedure to calculate an optimum solution for 0-1 integer linear programming problems. The number of the steps which each protocol entity needs to simulate one transition in the service specification is also minimized. Ways to avoiding conflict of registers are also described. Our approach has the following advantages. First, parallel events can be described in a service specification. Secondly, many practical systems can be described in the MGR model. Finally, at the protocol specification level, we can understand what events can be executed in parallel.

In clad contacts of bonded dissimilar metals used in relays and switches, the bonding state affects the switching performance of those devices. Examining the bonding state and analyzing the relationship between the bonding state and the causes of malfunction, such as welding of the contact, leads to improvement in reliability of electromechanical devices. In this experiment we examined, with an ultrasonic microscope, the bonding state in riveted clad contacts which had been subjected to load-breaks of in-rush current, and were able to demonstrate the causal relation of the bonding state with malfunctions of the contacts. The use of the ultrasonic microscope made it possible to perform a hitherto difficult detailed analysis of the bonding state of clad contacts. It was also confirmed that this was an extremely effective method for studying the relationship with switching performance.

Given a sorted set S of n points in the plane, the prefix convex hulls problem of S is to compute the convex hull for every prefix set of S. We present a parallel algorithm for this problem. Our algorithm runs in O(logn) time using n/logn processors in the CREW PRAM computational model. The algorithm is shown to be time and cost optimal. One of the techniques we adopt to achieve these optimal bounds is the use of a new parallel data structure Array-Tree.

A new method for the accurate extraction of glottal source parameters is proposed. This method, called Heuristic Analysis-by-Synthesis (HAbS), has been developed specifically to overcome the weaknesses of other methods of glottal source parameter extraction. The specific features of this method are the use of the AbS method for extraction of glottal source and vocal tract parameters, the use of a parametric glottal source model during vocal tract analysis, the use of alternating glottal source and vocal tract analyses, and simultaneous, time-domain analysis of the glottal source parameters and the first formant. This method has been implemented in such a way that user interaction is not required. The performance of the HAbS method is evaluated using both synthetic-speech and natural-speech data. Error is measured in both the time domain and the spectral domain, and the standard deviation of extracted parameter values is computed. In addition, the error in analysis of each glottal-source parameter is computed using synthetic-speech data. In order to assess the accuracy of the HAbS method as compared to other methods, three other methods (LPC, AIF, and AbS) are evaluated using the same data methods of error measurement. From these evaluations, it is clear that the HAbS method yields results that are more accurate than these other methods.

A globally and quadratically convergent algorithm is presented for solving nonlinear resistive networks containing transistors modeled by the Gummel-Poon model or the Shichman-Hodges model. This algorithm is based on the Katzenelson algorithm that is globally convergent for a broad class of piecewise-linear resistive networks. An effective restart technique is introduced, by which the algorithm converges to the solutions of the nonlinear resistive networks quadratically. The quadratic convergence is proved and also verified by numerical examples.

The stability of a terminated two-port network is investigated, and the stability conditions with only one inequality are obtained. Furthermore, the stability conditions with two inequalities, which are in the same form as those for the passive terminations known at the present time, are also obtained.

Kalman filter is an essential tool in signal processing, modern control and communications. The filter estimates the states of a given system from noisy measurements, using a mean-square error criterion. Although Kalman filter has been shown to be very versatile, it has always been computationally intensive since a great number of matrix computations must be performed at each iteration. Thus the exploitation of this technique in broadband real time applications is restricted. The solution to these limitations appears to be in VLSI (very large scale integration) architectures for the parallel processing of data, in the form of systolic architectures. Systolic arrays are networks of simple processing cells connected only to their nearest neighbors. Each cell consists of some simple logic and has a small amount of local memory. Overall data flows through the array are synchronously controlled by a single main clock pulse. In parallel with the development of Kalman filter, the square root covariance and the square root information methods have been studied in the past. These square root methods are reported to be more accurate, stable and efficient than the original algorithm presented by Kalman. However it is known that standard SRIF is less efficient than the other algorithms, simply because standard SRIF has additional matrix inversion computation and matrix multiplication which are difficult to implement in terms of speed and accuracy. To solve this problem, we use the modified Faddeeva algorithm in computing matrix inversion and matrix multiplication. The proposed algorithm avoids the direct matrix inversion computation and matrix multiplication, and performs these matrix manipulations by Gauss elimination. To evaluate the proposed method, we constructed an efficient systolic architecture for standard SRIF using the COMPASS design tools. Actual VLSI design and its simulation are done on the circuits of four type processors that perform Gauss elimination and the modified Givens rotation.

Mode separation of a multiplex mode in a mode-division multiplexing system is studied. The clear, desired single-mode pattern, which is separated from the multiplex mode by using a holographic filter, is observed in the experiment.

In this paper, we first discuss on a framework for a 3D image display system which is the combination of passive sensing and active display technologies. The passive sensing enables to capture real scenes under natural condition. The active display enables to present arbitrary views with proper motion parallax following the observer's motion. The requirements of passive sensing technology for 3D image displays are discussed in comparison with those for robot vision. Then, a new stereo algorithm, called SEA (Stereo by Eye Array), which satisfies the requirements is described in detail. The SEA uses nine images captured by a 33 camera array. It has the following features for depth estimation: 1) Pixel-based correspondence search enables to obtain a dense and high-spatial-resolution depth map. 2) Correspondence ambiguity for linear edges with the orientation parallel to a particular baseline is eliminated by using multiple baselines with different orientations. 3) Occlusion can be easily detected and an occlusion-free depth map with sharp object boundaries is generated. The feasibility of the SEA is demonstrated by experiments by using real image data.

This paper describes an image synthesis method based on an estimation of camera parameters. In order to acquire high quality images using image synthesis, we take some constraints into account, which include angle of view, synchronization of change of scale and change of viewing direction. The proposed method is based on an investigation that any camera operation containing a change of scale and a pure 3D rotation can be represented by a 2D geometric transformation. The transformation can explain all the synthesis procedure consisting of locating, synchronizing, and operating images. The procedure is described based on a virtual camera which is constituted of a virtual viewing point and a virtual image plain. The method can be efficiently implemented in such a way that each image to be synthesized undergoes the transformation only one time. The parameters in the image transformation are estimated from image sequence. The estimation scheme consists of first establishing correspondence and then estimating the parameters by fitting the correspondence data to the transformation model. We present experimental results and show the validity of the proposed method.

In this paper we estimate the number of permutations realizable in fault-tolerant multistage interconnection networks designed to tolerate faults on any switching element. The Parallel Omega network and the INDRA network are representative types of fault-tolerate multistage interconnection networks designed to tolerate a single fault. In order to evaluate the enhancement in the function of network by preparing the hardware redundancy for fault-tolerance, we estimate the number of permutations realizable in fault-tolerant networks. This result enables us to set up a standard to evaluate the hardware redundancy required to tolerate multifaults from the viewpoint of the enhancement of network function. This paper concludes that in the case where the number of inputs is up to 32 the increase ratio of the number of realizable permutations is no more than 1/0.73 even if the tolerance to multifaults is prepared instead of the tolerance to a single fault.

This paper is concerned with the data compression and interpolation of multi-view image set. In this paper, we propose a novel disparity compensation scheme based on geometric relationship. We first investigate the geometric relationship between a point in the object space and its projection onto view images. Then, we propose the disparity compensation scheme which utilize the geometric constraints between view images. This scheme is used to compress the multi-view image into the structure of the triangular patches and the texture data on the surface of patches. This scheme not only compresses the multi-view image but also synthesize the view images from any viewpoints in the viewing zone. Also, this scheme is fast and have compatibility with 2-D interframe coding. Finally, we report the experiment, where two sets multi-view image were used as original images and the amount of data was reduced to 1/19 and 1/20 with SNR 34 dB and 20 dB, respectively.

Ultrafast MR imaging (e.g., echo-planar imaging) acquires all the data within only several tens of milliseconds. This method, however, is affected by static magnetic field inhomogeneities and chemical shift; therefore, a high degree of field homogeneity and water and fat signal separation are required. However, it is practically impossible to obtain an homogeneous field within a subject even if in vivo shimming has been performed. In this paper, we describe a new ultrafast MR imaging method called Ultrafast Single-shot water and fat Separated Imaging (USSI) and a correction method for field inhomogeneities and chemical shift. The magnetic field distribution whthin the subject is measured before thd scan and used to obtain images without field inhomogeneity distortions. Computer simulation results have shown that USSI and the correction method can obtain water and fat separated images as real and imaginary parts, respectively, of a complex Fourier transform with a single-shot scan. Image quality is maintained in the presence of field inhomogeneities of several ppm similar to those occurring under practical imaging conditions. Limitations of the correction method are also discussed.

Recent achievements in low-voltage and low-power circuit techniques are reported in this paper. DC current in low-voltage CMOS circuits stemming from the subthreshold current in MOS transistors, is effectively reduced by applying switched-power-line schemes. The AC current charging the capacitance in DRAM memory arrays is reduced by a partial activation of array blocks during the active mode and by a charge recycle during the refresh mode. A very-low-power reference-voltage generator is also reported to control the internal chip voltage precisely. These techniques will open the way to using giga-scale LSIs in battery-operated portable equipment.

A novel isolation structure which has a buried insulator between polysilicon electrodes (BIPS) has been developed. The BIPS isolation employs the refilling CVD-oxides in openings between polysilicon electrodes by photoresist etchback process. Device characteristics and parasitic effects of BIPS isolation have been compared with that of LOCOS isolation. Using BIPS isolation, we can almost suppress the narrow-channel effects and achieve the deep submicron isolation. No degradation on the subthreshold decay of devices with BIPS isolation can be obtained. The use of BIPS isolation technology yields a DRAM cell of small area. The successful fabrication of deep submicron devices with BIPS isolation clearly demonstrates that this technology has superior ability to overcome the LOCOS isolation.

A method is described for constructing an interpolant to a set of arbitrary data points (xi, yi), i1, 2, , n. The constructed interpolant is a piecewise parametric cubic polynomial and satisfies C1 continuity, and it reproduces all parametric polynomials of degree two or less exactly. The experiments to compare the new method with Bessel method and spline method are also shown.

We present an 8-dimensional trellis-coded 8-PSK with a symbol transition constraint that is similar to that of π/4-shift quadrature phase shift keying (QPSK). This scheme can achieve a coding gain of 1.6 to 2.4 dB at the same rate of π/4-shift QPSK on Gaussian channel, and it has also an immunity against the integer multiples of 90 phase ambiguities. In order to label the constellation of the proposed scheme, a constellation partitioning algorithm is presented. This algorithm, on the basis of set partitioning, can be used to label the signal constellation with no coset structure.

This paper presents an overview of the SDC-I (Super Database Computer I) developed at the University of Tokyo, Japan. The purpose of the project was to build a high performance SQL server which emphasizes query processing over transaction processing. Recently relational database systems tend to be used for heavy decision support queries, which include many join, aggregation, and order-by operations. At present high-end mainframes are used for these applications requiring several hours in some cases. While the system architecture for high traffic transaction processing systems is well established, that for adhoc query processing has not yet adequately understood. SDC-I proved that a parallel machine could attain significant performance improvements over a coventional sequential machine through the exploitation of the high degree of parallelism present in relational query processing. A unique bucket spreading parallel hash join algorithm is employed in SDC, which makes the system very robust in the presense of data skew and allows SDC to attain almost linear performance scalability. SDC adopts a hybrid parallel architecture, where globally it is a shared nothing architecture, that is, modules are connected through the multistage network, but each module itself is a symmetric multiprocessor system. Although most of the hardware elements use commodity microprocessors for improved performance to cost, only the interconnection network incorporates the special function to support our parallel relational algorithm. Data movement over the memory and the network, rather than computation, is heavy for I/O intensive database processing. A dedicated software system was carefully designed for efficient data movement. The implemented prototype consists of two modules. Its hardware and software organization is described. The performance monitoring tool was developed to visualize the system activities, which showed that SDC-I works very efficiently.

A new frequency hopped spread spectrum system is introduced. The frequency hopped signal is a combination of multi frequency and multi phase signals and is referred to as Frequency Hopped/Joint Frequency-Phase Modulation (FH/JFPM). A noncoherent receiver for the FH/JFPM signals is introduced and an exact expression for the bit error rate is obtained. A performance analysis of this system is given in the presence of broadband and partial-band noise jamming. The optimal jamming strategy is evaluated. The results show that under these jamming conditions the FH/JFPM perform better than the FH/M-ary DPSK and FH/M-ary FSK systems. It is also shown that for a given channel bandwidth and data rate, the FH/JFPM system has more processing gain than its FSK or DPSK counterparts.