The mesh-connected computers with hyperbus broadcasting are an extension of the mesh-connected computers with multiple broadcasting. Instead of using local buses, we use global buses to connect processors. Such a strategy efficiently reduces the time complexity of the semigroup problem from O(N) to O(log N). Also, the matrix multiplication and the transitive closure problems are solved in O(log N) and O(log2 N) time, respectively. Then, based on these operations, several interesting problems such as the connected recognition problem, the articulation problem, the dominator problem, the bridge problem, the sorting problem, the minimum spanning tree problem and the bipartite graph recognition problem can be solved in the order of polylogarithmic time.

In this work, a new structure of M-channel linear-phase paraunitary filter banks is proposed, where M is even. Our proposed structure can be regarded as a modification of the conventional generalized linear-phase lapped orthogonal transforms (GenLOT) based on the discrete cosine transform (DCT). The main purpose of this work is to overcome the limitation of the conventional DCT-based GenLOT, and improve the performance of the fast implementation. It is shown that our proposed fast GenLOT is superior to that of the conventional technique in terms of the coding gain. This work also provides a recursive initialization design procedure so as to avoid insignificant local-minimum solutions in the non-linear optimization processes. In order to verify the significance of our proposed method, several design examples are given. Furthermore, it is shown that the fast implementation can be used to construct M-band linear-phase orthonormal wavelets with regularity.

High resolution algorithms in sensor arrays lead to accurate results but with expensive eigendecompositions making its use in real-time applications such as mobile communications relatively difficult. In this paper, a trade-off between accuracy and computational load is accomplished through a simplified algorithm which instead of eigendecompositions, uses the robust QR decomposition for which many effcient parallel (systolic, wavefront array) implementations exist. First, a simple detection scheme is presented and, through simulations, is shown to work very well for sufficient SNR, even when signals are coherent. Outputs of the detection process include simultaneously estimates of signals Direction Of Arrivals (DOA's) and a simple beamformer vector resulting in an estimate of the desired signal. Extensive simulations are performed assuming different scenarios of variations in SNR, DOA's leading to discussions on the possibilities and limitations of the proposed solution.

We present a minimal lattice realization of MIMO linear discrete-time systems which interpolate the desired Markov and covariance parameters. The minimal lattice realization is derived via a recursive construction algorithm based on the state space description and it parametrizes all the interpolants.

A new CMOS analogue transconductor is proposed and simulated. This transconductor is based on the operation of MOS transistors in the linear region and has a good linearity. The simulation result shows that less than 1% distortion can be obtained for the differential input signal of 6.4 Vp-p with IB=80µA and supply voltage of 5V.

Intending to contribute to constructing better multimedia network systems, we propose a new concept of image database system of which form of storage is featuring exponential or graceful oblivion and abrupt recollection like the human memory property. By virtue of this property of database storages that is realized by employing hierarchical or pyramidal image coding, the database memory and transmission costs can be significantly reduced. In this paper we will describe the details of the concept, the results of theoretical analysis based on a simplified model which reveals the effectiveness of the proposed system, the structure of an experimental prototype system and the result of an experimental image retrieval service carried out by implementing it over ATM high speed channels.

Orthogonal frequency division multiplexing (OFDM) has been receiving a lot of attention in the field of broadcasting because of its ruggedness under multipath environments. One of important issues to realize high quality reception of OFDM signals is to correct frequency and timing offsets between the transmitter and receiver so that orthogonality of the carriers can be maintained. This paper discusses a frequency and timing period acquisition technique for OFDM systems. A new offset estimation technique is introduced that detects both the frequency and timing peirod offsets at the same time by using only one pilot symbol with its suitable frequency assignment. A pseudo noise (PN) sequence is also introduced to assign these frequencies of the pilot symbol so that the frequency acquisition range can be widened. Numerical examples are given to show the estimate variances of the proposed frequency and timing period estimator over both additive white Gaussian noise (AWGN) and multipath fading channels. Also the bit error rate (BER) performance for an open loop acquisition system is examined.

Copper strips plated with Sn-Pb eutectic solder were hot pressure-bonded to gold thin-film wiring. It was proven that a Au-Sn alloy forms at the interconnection between the gold thin film and the copper strip, but that there is virtually no Pb present in the interconnection. Au, Sn, and Pb were observed on the surfaces of the copper strips and the gold thin film outside of the connection area.

For reducing requirement of large memory and minimizing computation complexity in a large-vocabulary continuous speech recognition system, speech segmentation plays an important role in speech recognition systems. In this paper, we formulate the speech segmentation as a two-phase problem. Phase 1 (frame labeling) involves labeling frames of speech data. Frames are classified into three types: (1) silence, (2) consonant and (3) vowel according to two segmentation features. In phase 2 (syllabic unit segmentation) we apply the concept of transition states to segment continuous speech data into syllabic units based on the labeled frames. The novel class of hyperrectangular composite neural networks (HRCNNs) is used to cluster frames. The HRCNNs integrate the rule-based approach and neural network paradigms, therefore, this special hybrid system may neutralize the disadvantages of each alternative. The parameters of the trained HRCNNs are utilized to extract both crisp and fuzzy classification rules. In our experiments, a database containing continuous reading-rate Mandarin speech recorded from newscast was utilized to illustrate the performance of the proposed speaker independent speech segmentation system. The effectiveness of the proposed segmentation system is confirmed by the experimental results.

This paper first presents the performance analysis of the NACF algorithm. The results show the possibility of the degradation in the convergence speed. To improve the convergence speed, the bias term is introduced into the NACF algorithm and its efficiency is investigated through the computer simulations.

We have studied liquid crystal (LC) alignment on UV-irradiated poly(vinyl cinnamate)(PVCi)films by using the texture observations and the anchoring energy measurements. Irradiation of the PVCi films with linearly-polarized UV light creates the optical anisotropy in the films, and the anisotropy can well align LCs perpendicular to the UV polarization. We discuss the LC alignment mechanisms and point out the important contribution from non-dimerized side chains of PVCi molecules. The anchoring energies on photo-processed PVCi films are shown to be smaller than those on conventional rubbed polyimide films. We propose a new method to generate pretilt angle on the photo-processed PVCi films, and successful results of pretilt angle generation are demonstrated. This method is applied to fabricate TN- and super-multidomain TN-LCDs, and the good electro-optical performance of the LCDs is confirmed.

A new ATM switch architecture, named shared multibuffering, features great advantages on memory access speed for a large switch, and overall size of buffer memories to achieve excellent cell-loss performance. We have developed a 622-Mb/s 88 shared multibuffer ATM switch with multicast functions and hierarchical queueing functions to accommodate 156-Mb/s, 622-Mb/s and 2.4-Gb/s interfaces. Implementation of the shared multibuffer ATM switch is described with respect to the four sorts of 0.8-µm BiCMOS LSIs and ATM switch boards. The switch board/type-1, with C1-LSI, allows to accommodate effectively 156-Mb/s and 622-Mb/s interfaces, which is suitable for an ATM access system. The switch board/type-2, with C2-LSI, can provide multicast functions and accommodate a 2.4-Gb/s interface. By using four switch boards, it is possible to apply them to a 2.4-Gb/s ATM loop system.

Amorphous silicon thin film transistors(a-Si TFTs) with a channel-etched structure were fabricated. The key technologies to realize these simple-process TFTs were 1) fabricating data lines and pixel electrodes of indium tin oxide(ITO); 2) carrying out tapered dry etching of plural layers of the a-Si and gate insulator silicon nitide; and 3) forming silicide layer to reduce the contact resistance between the phosphorousdoped a-Si and ITO. Excellent image quality, with a high contrast ratio of more than 100: 1, was obtained for video graphic array(VGA) mode TFT-LCDs using a dot inversion driving method. Furthermore, the transmission distribution was uniform with less than a 4.5% deviation on the whole display area although the ITO data line resistances were as large as 120 kΩ per line.

This paper concerns optimized facility design for VLSI production. The methods proposed are applicable in planning LSI production facilities with a good balance between the number of machines and the number of operators. The sequence in each processing step is analyzed in detail. A new algorithm based on the queueing model is developed for estimating the simultaneous requirements for the two kinds of resources, machines and operators. This estimation system can be applied to complicated fabrication schemes, such as batch processing, continuous processing, and mixed technologies. This methodology yields guidelines for ASIC LSI production system design.

This paper presets a fast computation algorithm for connection admission control for heterogeneous delay sensitive traffic in ATM networks. Cell loss probability is adopted as the measure of quality of service. In our study, cells of each connection are allowed to have two different loss priorities and the aggregate traffic can have more than two. To cope with multiple quality of service requirements, the link capacity is divided into several bands. For simplicity, each traffic source is assumed to alternate between active and idle periods. However, the results can be extended to traffic sources having more than two states. Upper bounds of actual cell loss probabilities are derived based on the bufferless fluidflow model. Numerical results show that the upper bounds are close to the actual cell loss probabilities.

Physical optics(PO) and the aperture field integration method (AFIM) give accurate and similar field patterns near the first few sidelobes of reflector antennas. It is widely accepted that the use of AFIM is restricted to norrower angles than PO. In this paper, uniform equivalent edge currents of PO and AFIM are compared analytically and their equivalence in high frequency in discussed. It is asymptotically verified that the patterns by AFIM are almost identical to PO fields in the full 360angular region, provided that AFIM uses the equivalent surface currents consisting of two components, that is, the geometrical optics(GO) reflected fields from the reflector and the incident fields from the feed source, the latter of which are often neglected. Slightly weaker equivalence is predicted for cross polarization patterns. Numerical comparison of PO and AFIM confirms all these results, the equivalence holds not only for large but also for a very small refiector of the order of one wavelength diameter.

This paper proposes a hierarchical parallel processing system for the multipass rendering method. The multipass rendering method based on the integration of radiosity and ray-tracing can synthesize photo-realistic images. However, the method is also computationally expensive. To accelerate the multipass rendering method, the system, called (Mπ)2, employs two kinds of parallel processing schemes. As a coarse-grain parallel processing, object-space parallel processing with multiple processing elements based on the object-space subdivision is adapted, and each processing element (PE) is equipped with multiple pipelined units for a fine-grain parallel processing. To balance load among the system, static load balancing at the PE level and dynamic load balancing at the pipelined unit level within the PE are introduced. Especially, we propose a novel static load allocation scheme, skewed-distributed allocation, which can effectively distribute a three-dimensional object space to one- or two-dimensional processor configuration of the (Mπ)2 system. Simulation experiments show that the two-dimensional (Mπ)2 systems with the skewed-distributed allocation outperform the three-dimensional systems with the non-skewed distributed allocation. Since lower dimensional systems can be built at a lower cost than higher dimensional systems, the skewed-distributed allocation will be meritorious. Besides, by the combination of static load balancing by the skewed-distributed allocation and the dynamic load balancing by dynamic ray allocation within each PE, the system performance can be further boosted. We also propose a cached frame buffer system to relieve access collision on a frame buffer.

The transform coding scheme is often used for data compression of images, but the blocking effects peculiar to the scheme appear more clearly in reproduced images as a coding rate (bits/pixel) decreases. These effects can sometimes be viewed as a periodical square-grid overlaying the images. In this paper,we propose a new method for selectively measuring the above blocking effects among several types of image degradation by means of the techniques of nonlinear signal processing for spectral infomation (cepstral techniques), in order to compare the amount of blocking effects for the different coding images. First a two-component model which consists of DC and AC images, is discussed from a viewpoint of subimage-by-subimage coding, and some basic properties of cepstral information for the model are investigated. Then we show a procedure to compute the cepstral information for two-dimensional image signals taking the horizontal and vertical directions ioto account, and introduce a cepstral mean square error (CMSE) as a new measure to estimate the amount of blocking effects. The computer simulation results for some test images using different coding schemes show that the amount of blocking effects in each image can be easily measured and estimated by this method even when the blocking effects appear slightly.

In this paper, quantization method which can keep the phase and gain characteristics of a reference filter is proposed. The proposed method uses a genetic algorithm and a simulated annealing algorithm. The objective function used in this method is described with two kinds of weighting functions for identifying the phase and gain characteristics respectively. Therefore, the quantization accuracy on the gain characteristic is independent of the accuracy on the phase characteristic. Further, the proposed algorithm can be applied to any types of filters, because the chromosome expresses only their coefficients values. The efficiency of the proposed algorithm is verified by some experiments.

This paper presents a new method for designing IIR Nyquist filters with zero intersymbol interference. It is shown that IIR Nyquist filters with zero intersymbol interference have some constraints on frequency response, i.e., both magnitude and phase error in passband are dependent on stopband error. Therefore, the frequency response is required to optimize only in stopband. The proposed procedure is based on the formulation of an eigenvalue problem by using Remez multiple exchange algorithm in stopband. Then, the filter coefficients can be computed by solving the eigenvalue problem, and the optimal solution with equiripple stopband response is easily obtained by applying an iteration procedure. The proposed procedure is more computationally efficient than the conventional methods.