We develop a simulation environment for designing and examining a neural network model at the network level. The aim of our research is to enable researchers investigating neural network connective models to save time by being equipped with a graphical user interface and database of the network models. This environment consists of three parts: (1) the kernel of the simulation system, (2) NNDBMS (Neural Networks DataBase Management System), and (3) a system for displaying simulation results in various ways.

Stable phase locked states" are found amongst the equiliblia of the phasor model known as a generalized Hopfield model having complex-valued local states on the unit circle with centre at the origin. The asynchronous updating rule is assumed, and the energy decreasing characteristic is used to investigate a property of the equilibrium states. Some of the equilibria are shown to be fragile" in the sense that the energy is not locally convex. It is also shown that the local convexity of the energy is assured by a sort of consistency between the equilibrium and the connection weights.

The objective of this paper is to find a parametric representation for the vocal-tract log-area function that is directly and simply related to basic acoustic characteristics of the human vocal-tract. The importance of this representation is associated with the solution of the articulatory-to-acoustic inverse problem, where a simple mapping from the articulatory space onto the acoustic space can be very useful. The method is as follows: Firstly, given a corpus of log-area functions, a parametric model is derived following a factor analysis technique. After that, the articulatory space, defined by the parametric model, is filled with approximately uniformly distributed points, and the corresponding first three formant frequencies are calculated. These formants define an acoustic space onto which the articulatory space maps. In the next step, an independent component analysis technique is used to determine acoustic and articulatory coordinate systems whose components are as independent as possible. Finally, using singular value decomposition, acoustic and articulatory coordinate systems are rotated so that each of the first three components of the articulatory space has major influence on one, and only one, component of the acoustic space. An example showing how the proposed model can be applied to the solution of the articulatory-to-acoustic inverse problem is given at the end of the paper.

This paper presents the results of a simulation study of blocking and non-blocking switching for hierarchical ring networks. The switching techniques include wormhole, virtual cut-through, and slotted ring. We conclude that slotted ring network performs better than the more popular wormhole and virtual cut-through networks. We also show that the size of the node buffers is an important parameter and that choosing them too large can hurt performance in some cases. Slotted rings have the advantage that the choice of buffer size is easier in that larger than necessary buffers do not hurt performance and hence a single choice of buffer size performs well for all system configurations. In contrast, the optimal buffer size for virtual cut-through and wormhole switching nodes varies depending on the system configuration and the level in the hierarchy in which the switching node lies.

This paper discusses a massively parallel interconnection scheme for multithreaded architecture and introduces a new class of direct interconnection networks called the hierarchical Multidimensional Directed Cycles Ensemble (hMDCE). Its suitability for massively parallel systems is discussed. The network is evolved from the Multidimensional Directed Cycles Ensemble (MDCE) network, where each node is substituted by lower-level sub-networks. The new network addresses some serious problems caused by the increasing scale of parallel systems, such as longer latency, limited throughput and high implementation cost. This paper first introduces the MDCE network and then presents and examines in detail the hierarchical MDCE network. Bisection bandwidth of hMDCE is considerably reduced from its ancestor MDCE and the network performs significantly higher throughput and lower latency under some practical implementation constraints. The gate count and delay time of the compiled circuit for the routing function are insignificant. These results reveal that the hMDCE network is an important candidate for massively parallel systems interconnection.

A mesh spiral network (MSnet) and a mesh random (MRnet) are proposed. The MSnet consists of the 2-D torus and bypass links that keep the degree at six. The MRnet consists of the 2-D torus and random bypass links that keep the degree at six. The diameter and the average distance are calculated by using a computer program. The cost of the MSnet is slightly higher than that of the de Bruijn graph, and is about the same as the Star graph. The cost of the MRnet is better than that of the de Bruijn graph. The MSnet is proven to be maximally fault-tolerant. The upper bound of the MRnet size is also discussed.

The medial axis transform (MAT) is an image representation scheme. For a binary image, the MAT is defined as a set of upright maximal squares which consist of pixels of value l entirely. The MAT plays an important role in image understanding. This paper presents a parallel algorithm for computing the MAT of an n n binary image. We show that the algorithm can be performed in O(log n) time using n2/log n processors on the EREW PRAM and in O(log log n) time using n2/log log n processors on the common CRCW PRAM. We also show that the algorithm can be performed in O(n2/p2 + n) time on a p p mesh and in O(n2/p2 + (n log p)/p) time on a p2 processor hypercube (for 1 p n). The algorithm is cost optimal on the PRAMs, on the mesh (for 1 p n) and on the hypercube (for 1 p n/log n).

This paper presents a method for mechanically transforming a parallel algorithm on an original network so that the algorithm can work on a target network. It is assumed that the networks are of cube-type such as the shuffle-exchange network, omega network, and hypercube. Were those networks isomorphic to each other, the algorithm transformation is an easy task. The proposed transformation method is based on a novel graphembedding scheme <φ: δ, κ, π, ψ>. In addition to the dilating operation δ of the usual embedding scheme <φ: δ>, the novel scheme uses three primitive graph-transformation operations; κ (= δ-1) for contracting a path into a node, π for pipelining a graph, and ψ (= π-1) for folding a pipelined graph. By applying the primitive operations, the cube-type networks can be transformed so as to be isomorphic to each other. Relationships between the networks are represented by the composition of applied operations. With the isomorphic mapping φ, an algorithm in a node of the original network can be simulated in the corresponding node(s) of the target network. Thus the algorithm transformation is reduced to routine work.

2D (two-dimensional) convolution is a basic operation in image processing and requires intensive computation. Although the SIMD model is considered suitable for 2D convolution, previous 2D convolution algorithms on the SIMD model assume unbounded number of PEs (Processing Elements) available, which we call unbounded case. Unbounded case could not be satisfied on real computers. In this paper, time-optimal data-parallel 2D convolution is studied on mesh-connected SIMD computers with bounded number of PEs. Because the optimal computation complexity is not difficult to achieve, the main concern of this paper is how to achieve optimal communication complexity. Firstly the lower bound computation complexity is analyzed. Then the lower bound communication complexities are analyzed under two typical data-distribution strategies: block-mapping and cyclic-mapping. Based on the analysis result, an optimal algorithm is presented under the block-mapping. The algorithm achieves the lower bound complexity both in computation and in communication.

The effect of silicone vapour concentration on the contact failure was examined by using micro relays and motor brush-slip ring(commutator) contacts, [(CH3) 2SiO]4: D4 was used as a vapour source of silicone contamination. Because the influence of the vapour of the silicone on the contact surface can not be avoided at all times due to its gradual evaporation in the atmosphere. The contact failure caused by the silicone vapour was confirmed as formation of SiO2 on the contact surfaceby analysis of EPMA and XPS. A minimum limiting concentration level which does not affect contact reliability was found. This limiting level was 10 ppm(O.13mg/l). Validity of the limiting level was confirmed by the relationships among concentration, temperature, SiO2 film thickness and contact resistance. Furthermore, the effect of the degree of silicone polymerization on the limiting concentration was derived by an empirical formula. This silicone is found to have polymerization degree larger than D7: n=7. These results were confirmed by the contact failure data due to the silicone contamination.

We report recent progress in the development of Liquid Crystal(LC) materials for the TN-TFT and ECB-TFT technologies, which require LC materials with positive and negative dielectric anisotropy, respectively. Many kinds of new LC materials have been synthesized and have been evaluated based on their fundamental physical properties. We have succeeded in identifying new LC materials, and developing new LC mixtures based on those, so that the current typical requirements of TFT-LCDs e.g. fast switching times, low power consumption, good viewing angles and wide operation temperature ranges together with high reliability can be fulfilled.

The characteristics of a-Si bottom-gate TFT test devices with several kinds of inorganic "quasi-black matrix," such as metal, semiconductor, and insulator, on the top were investigated for various black matrix(BM) resistivities. In the Ia-Vg characteristics, for a BM sheet resistance of about1 1012 Ω/, a high off current and large Vth shift were observed due to the back-gating effects when the BM is charged up. Accrding to the ac dynamic characteristics, there was almost no leakage due to the capacitive coupling between source and drain after 16.6 msec(one frame) when the BM sheet resistance was above 7 1013 Ω/ . It was found that hydrogenated amorphous silicon germanium(a-SiGe:H) film, which has enough optical density, with the sheet resistance above the order of 1014 Ω/ is a promising candidate for an inorganic BM on TFT array.

In this work is first presented that a PDLC film with a ferroelectric alignment layer realizes a bistable switching in similar to the surface-stabilised ferroelectric liquid crystal display devices. Such a bistability is found to critically depend on the squareness parameter of the ferroelectric layer as well as such material properties of the dispersed nematics as the elastic and the dielectric constants. It is also found that there exists an appropriate elastic constant to improve the optical transmittance. The dependence of the distribution of the radii of the nematic droplets on the electro-optic bistability is also investigated in detail by means of the numerical computations assuming a fractal distribution. The fundamental electro-optic properties of the presently, proposed PDLC cells imply the advantage beyond the conventional PDLC without any ferroelectric alignment layer.

Super twisted nematic (STN) liquid crystal displays(LCDs) using spiral polymer aligned nematic (SPAN) liquid crystals have been achieved by photo-polymerization of some kinds of chiral monoacrylates in liquid crystalline hosts.The spiral polymer made of a chiral monoacrylate in STN LCD has effect to reduce the driving voltage without any disadvantages for the STN LCD. The relation of chemical structure of a chiral monoacrylate and nature of spiral polymer is discussed.

Various reconfiguration schemes against faults of mesh-connected processor arrays have been proposed. As one of them, the mesh-connected processor arrays model based on single-track switches was proposed in [1]. The model has an advantage of its inherent simplicity of the routing hardware. Furthermore, the 2 track switch model [2] and the multiple track switch model [3] were proposed to enhance yields and reliabilities of arrays. However, in these models, Simplicity of the routing hardware is somewhat lost because multiple tracks are used for each row and column. In this paper, we present a builtin self-reconstruction approach for mesh-connected processor arrays which are partitioned into sub-arrays each using single-track switches. Spare PEs which are located on the boundaries of the sub-arrays compensate faulty PEs in these sub-arrays. First, we formulate a reconfigulation algorithm for partitioned mesh-arrays using a Hopfield-type neural network, and then its performance for reconfigulation in terms of survival rates and reliabilities of arrays and processing time are investigated by computer simulations. From the results, we can see that high reliabilites are achieved while processing time is a little and hardware overhead (links and switches) required for reconstruction is as same as that for the track switch model. Next, we present a hardware implementation of the neural algorithm so that a built-in self-reconfigurable scheme may be realized.

We studied a 0.15-µm InGaP/InGaAs/GaAs pseudomorphic HEMT operating under a negative drain bias, using a parameter extraction technique based on an analytical parameter transformation. The bias-dependent data of smallsignal equivalent circuit elements was obtained from Sparameters measured at up to 62.5 GHz at various bias settings. We then described the intrinsic part of the device using a new empirical large-signal model in which charge conservation and dispersion effects were taken into consideration. As far as we know, this is the first report to clarify the behavior of a HEMT operating under negative drain bias. We included our largesignal model in a commercially-available harmonic-balance simulator as a user-defined model, and designed a 60 GHz MMIC oscillator. The fabricated oscillator's characteristics agreed well with the design calculations.

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.

A laser power optimizing method for multi-pulse recording is described. Multi-pulse recording uses the recording pulse formed by bias part and comb part. To obtain best readout signal characteristics and reduce the time for optimizing, new mark pattern is recorded and then two parts of the recording pulse are individually adjusted by evaluating the detected signals during pre-write testing. At the optimized laser power by this method, a good qualitative eyepattern was obtained. As a result, this new method proves to be suitable for the multi-pulse recording and adapted to various disks with different recording properties.

This paper considers the estimation of speech parameters and their enhancement using an approach based on the estimation-maximization (EM) algorithm, when only noisy speech data is available. The distribution of the excitation source for the speech signal is assumed as a mixture of two Gaussian probability distribution functions with differing variances. This mixture assumption is experimentally valid for removing the residual excitation signal. The assumption also is found to be effective in enhancing noise-corrupted speech. We adaptively estimate the speech parameters and analyze the characteristics of its excitation source in a sequential manner. In the maximum likelihood estimation scheme we utilize the EM algorithm, and employ a detection and an estimation step for the parameters. For speech enhancement we use Kalman filtering for the parameters obtained from the above estimation procedure. The estimation and maximization procedures are closely coupled. Simulation results using synthetic and real speech vindicate the improved performance of our algorithm in noisy situations, with an increase of about 3 dB in terms of output SNR compared to conventional Gaussian assumption. The proposed algorithm also may be noteworthy in that it needs no voiced/unvoiced decision logic, due to the use of the residual approach.

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.