We have developed a 15-Gbit/s 96-gate Si-bipolar gate array using 0.5-µm Si-bipolar technology, a sophisticated internal cell design, an I/O buffer design suitable for high-speed operation and high-frequency package technology. The decision circuit and 4 : 1 multiplexer fabricated on the gate array operate up to 15-Gbit/s and above 10-Gbit/s respectively. The data input sensitivity and the phase margin of the decision circuit are 53 mVpp and 288 at 10-Gbit/s operation. This gate array promises to be useful in shortening the development period and lowering cost of 10-Gbit/s class IC's.

We propose an algorithm for image decomposition based on Hadamard functions, realized by answer-in-weights neural network, which has simple architecture and is explored with steepest decent method. This scheme saves memory consumption and it converges fast. Simulations with least mean square (LMS) and absolute mean (AM) errors on a 128128 image converge within 30 training epochs.

A data-base for data compression is universal if in its construction no prior knowledge of the source distribution is assumed and is optimal if, when we encode the reference index of the data-base, its encoding rate achieves the optimal encoding rate for any given source: in the noiseless case the entropy rate and in the semifaithful case the rate-distortion function of the source. In the present paper, we construct a universal data-base for all stationary ergodic sources, and prove the optimality of the thus constructed data-base for two typical methods of referring to the data-base: one is a block-shift type reference and the other is a single-shift type reference.

This paper proposes a human interface where a novel input method is used to substitute conventional input devices. It overcomes the deficiencies of physical devices, as it is based on image processing techniques. The proposed interface is composed of three parts: extraction of a person's handshape from a digitized image, detection of its fingertip, and interpretation by a software application. First, images of a pointing hand are digitized to obtain a sequence of monochrome frames. In each frame the hand is isolated from the background by means of gray-level slicing; with threshold values calculated dynamically by the combination of movement detection and histogram analysis. The advantage of this approach is that the system adapts itself to any user and compensates any changes in the illumination, while in conventional methods the threshold values are previously defined or markers have to be attached to the hand in order to give reference points. Second, once the hand is isolated, fingertip coordinates are extracted by scanning the image. Third, the coordinates are inputted to an application interface. Overall, as the algorithms are simple and only monochrome images are used, the amount of processing is kept low, making this system suitable to real-time processing without needing expensive hardware.

We have designed and implemented a simple yet powerful declarative synchronization mechanism for a paralle object-oriented computation model. The mechanism allows the user to control multiple message reception, specify the order of message reception, lock an invocation, and specify relations as invocation constraints. It has been included in a parallel object-oriented language, called A-NETL. The compiler and operating system have been developed on a total architecture, A-NET (Actors NETwork). The experimental results show that (i) the mechanism allows the user to model asynchronous events naturally, without losing the integrity of described programs; (ii) the replacement of the mechanism with the user's code requires tedious descriptions, but gains little performance enhancement, and certainly loses program readability and integrity; (iii) the mechanism allows the user to shift synchronous programs to asynchronous ones, with a scalable reduction of execution times: an average 20.6% for 6 to 17 objects and 46.1% for 65 objects. These prove the effectiveness of the proposed synchronization mechanism.

Data flow is a paradigm for concurrent computations in which a collection of parallel processes communicate asynchronously. For nondeterministic data flow networks many semantic models have been defined, however, it is complex to reason about the semantics of a network. In this paper, we introduce a transformation between data flow networks and the LOTOS specification language to make available theories and tools developed for process algebras for the semantic analysis based on traces of the networks. The transformation does not establish a one-to-one mapping between the traces of a data flow network and the LOTOS specification, but maps each network in a specification which usually contains more traces. The obtained system specification has the same set of traces as the corresponding network if they are finite, otherwise also non fair traces are included. Formal analysis and verification methods can still be applied to prove properties of the original data flow network, allowing in case of networks with finite traces to prove also network equivalence.

This paper presents a theoretically best algorithm within the framework of our image noise model for reconstructing 3-D from two views when all the feature points are on a planar surface. Pointing out that statistical bias is introduced if the least-squares scheme is used in the presence of image noise, we propose a scheme called renormalization, which automatically removes statistical bias. We also present an optimal correction scheme for canceling the effect of image noise in individual feature points. Finally, we show numerical simulation and confirm the effectiveness of our method.

This paper presents a simple and efficient method for estimation of parameters useful for textured image analysis. On the basia of a 2-D Wold-like decomposition of homogenenous random fields, the texture field can be decomposed into a sum of two mutually orthogonal components: a deterministic component and an indeterministic component. The spectral density function (SDF) of the former is a sum of 1-D or 2-D delta functions. The 2-D autocorrelation function (ACF) of the latter is fitted to the assumed anisotropic ACF that has an elliptical contour. The parameters representing the ellipse and those representing the delta functions can be used to detect rotation angles and scaling factors of test textures. Specially, rotation and scaling invariant parameters, which are applicable to the classification of rotated and scaled textured images, can be estimated by combining these parameters. That is, a test texture can be correctly classified even if it is rotated and scaled. Several computer experiments on natural textures show the effectiveness of this method.

Standard Site Method (SSM) is theoretically analyzed using matrix representations to examine its validity and develop an improved method. The analysis reveals that the SSM yields an antenna factor specifically related to the effective load impedance presented by the cable and associated devices which are disconnected from the antenna during the SSM site attenuation measurements. Therefore, an additional conversion is required to determine the desired antenna factor under actual load conditions. It is also concluded that the SSM is not applicable to antennas having height-dependent antenna factors. In addition, the SSM correction factors are found to be theoretically inappropriate. Uncertainty of the antenna factor obtained using the SSM is discussed and the required antenna separation distance is investigated. To improve the existing SSM, it is proposed that both transmitting and receiving antennas are placed at the same height during the site attenuation measurements. Experiments exhibit the superiority of the improved method.

Distributed computing over a network of workstations continues to be an illusive goal. Its main obstacle is the delay penalty due to network protocol and OS overhead. We present in this paper a low level hardware supported scheme for managing distributed shared memory (DSM), as an underlying paradigm for distributed computing. The proposed DSM is novel in that it employs a two-tier paging scheme that reduces the probability of false sharing and facilitates an efficient hardware implementation. The scheme employs a standard OS page and divides it into fixed smaller memory units called paragraphs, similar to cache lines. This scheme manages the shared data regions only, while other regions are handled by the OS in the standard manner without modification. A hardware extension of a traditional MMU, namely Distributed MMU or DMMU, is introduced to support the DSM. Shared memory coherency is maintained through a write-invalidate protocol. An analytical model is built to evaluate the system sensitivity to various parameters and to assess its performance.

A description language for matrix and vector expressions and its compiler for DSPs are shown. They provide both a user-friendly programming environment and efficient codes. In order to increase throughput and to reduce amount of methods based on mathematical laws are introduced. A method to decide the matrix and vector storage location suitable for processing on DSP is also proposed.

A rat-race hybrid-ring which includes a coupled-line called microwave C-section is proposed for size reduction. The perfect input match, isolation, equal power split and certain phase differences between two output ports can be satisfied at center frequency as in a normal hybrid-ring. The size of the proposed circuit becomes smaller than that of a normal rat-race built up with a folded non-coupled 3/4-wavelength transmission line, although the frequency characteristics are slightly damaged by the electromagnetic coupling between two folded strips. Theoretical results based on the even and odd mode decomposition method are in good agreement with those of the experimental circuit fabricated at 1 GHz.

This paper investigates the accepting powers of one-way alternatiog finite automata with counters and stack-counters (lafacs's) which operate in realtime. (The difference between counter" and stack-counter" is that the latter can be entered without the contents being changed, but the former cannot.) For each k0 and l0 ((k, l)(0, 0)), let 1AFACS(k, l, real) denote the class of sets accepted by realtime one-way alternating finite automata with k counters and l stack-counters, and let 1UFACS(k, l, real) (1NFACS(k, l, real)) denote the class of sets accepted by realtime one-way alternating finite automata with k counters and l stack-counters which have only universal (existential) states. We first investigate a relationship among the accepting powers of realtime lafacs's with only universal states, with only existential states, and with full alternation, and show, for example, that for each k0 and l0 ((k, l)(0, 0)), 1UFACS(k, l, real) 1NFACS(k, l, real) 1AFACS(k, l, real). We then investigate hierarchical properties based on the number of counters and stack-counters, and show, foe example, that for each k0 and l0 ((k, l)(0, 0)), and each X{U, N}, 1XFACS(k1, l, real)1AFACS(k, l, real)φ. We finally investigate a relationship between counters and stack-counters, and show, for example, that for each k0, l0 and m1, and each X{U, N}, 1XFACS(k, lm, real)1AFACS(k2m1, l, real)φ.

Ever increasing demand for higher bandwidth memories, which is fueled by multimedia and 3D graphics, seems to be somewhat satisfied with various emerging memory solutions. This paper gives a review of these emerging DRAM architectures and a performance comparison based on a condition to let the readers have some perspectives of the future and optimized graphics systems.

Concerning the complexity of tree drawing, the following result of Supowit and Reingold is known: the problem of minimum drawing binary trees under several constraints is NP-complete. There remain, however, many open problems. For example, is it still NP-complete if we eliminate some constraints from the above set? In this paper, we treat tree-structured diagrams. A tree-structured diagrm is a tree with variably sized rectangular nodes. We consider the layout problem of tree-structured diagrams on Z2 (the integral lattice). Our problems are different from that of Supowit and Reingold, even if our problems are limited to binary trees. In fact, our set of constraints and that of Supowit and Reingold are incomparable. We show that a problem is NP-complete under a certain set of constraints. Furthermore, we also show that another problem is still NP-complete, even if we delete a constraint concerning with the symmetry from the previous set of constraints. This constraint corresponds to one of the constraints of Supowit and Reingold, if the problem is limited to binary trees.

Recently, through high speed computer networks, multifarious information such as text, moving and still images, video, voice and control data is available. There is a natural demand to store such multimedia data in databases to facilitate their reuse in a wide variety of applications. Therefore, important research issues pertain to the investigation of appropriate database systems in multimedia computer network environments. In this paper, we first discuss the required technologies for multimedia information systems. Then we look at many multimedia information services through computer networks, and consider the importance of storing and effectively reusing such available multimedia data. To facilitate developing databases for use in these environments, we discuss the evolution of the notion of database systems. Finally, we demonstrate, as practical examples of such database systems, two prototype systems that we are currently implementing, i.e., the campus wide news on demand system and the ASN. 1 database system.

The firing squad synchronization problem is considered for defective cellular automata. A lower bound of time tf for the problem is derived. The state complexity to solve the problem is investigated and it is shown that the state set has to be arbitrary large to obtain solutions of time complexity (n). For memory-augmented defective cellular automata a tf-time solution is given.

We discuss how to determine automatically the number of mixture components in continuous mixture density HMMs (CHMMs). A notable trend has been the use of CHMMs in recent years. One of the major problems with a CHMM is how to determine its structure, that is, how many mixture components and states it has and its optimal topology. The number of mixture components has been determined heuristically so far. To solve this problem, we first investigate the influence of the number of mixture components on model parameters and the output log likelihood value. As a result, in contrast to the mixture number uniformity" which is applied in conventional approaches to determine the number of mixture components, we propose the principle of distribution size uniformity". An algorithm is introduced for automatically determining the number of mixture components. The performance of this algorithm is shown through recognition experiments involving all Japanese phonemes. Two types of experiments are carried out. One assumes that the number of mixture components for each state is the same within a phonetic model but may vary between states belonging to different phonemes. The other assumes that each state has a variable number of mixture components. These two experiments give better results than the conventional method.

This paper establishes a relationship among the accepting powers of deterministic, nondeterministic, and alternating one-way auxiliary pushdown automata, for any tape bound below n. Some other related results are also presented.

We frequently need to calculate the Neumann function Nν(x) of complex order ν numerically in order to solve boundary problems on electromagnetic fields. This paper presents a new method for the numerical calculation of Nν(x) of complex order ν. This method can calculate Nν(x) precisely even when the order ν is close to an integer n, and the algorithm by the method is very simple.