Human visual system can perceive 3-D structure of an object by binocular disparity, gradient of illumination (shading), occlusion, textures, perspective and so forth. Among them, binocular disparity seems to be the essentially important cues for the 3-D space perception and it is used widely for displaying 3-D visual circumstances such as in VR (virtual reality) system or 3-D TV. Visual illusions seem to be one of the phenomena which are purely reflecting the mechanism of human visual system. In the recent several years, the authors found several new types of 3-D visual illusions with binocular viewing. Entire 3-D illusory object including volume perception, transparency, dynamic illusions can be perceived only from the visual stimuli of disparity given by some inducing objects arranged with suitable relations. In this report, the authors introduced these newly found visual illusions and made some considerations on the human visual mechanism of 3-D perception and on their exploitation for new effective techniques in 3-D display. They introduced especially on the visual effect in two kinds of arrangement with occlusion and sustaining relationship between the illusory object and inducing objects. In the former case, the inducing objects which provide the stimuli were named as occlusion cues and classified into two types: contour occlusion cues and bulky occlusion cues. In the later case, those inducing objects were named as sustaining cues and a 3-D fully transparent illusory object was perceived. The perception was just like imagined from the scenes of the actions and positions of the pantomimists; then this phenomena was named as "Mime (Pantomime) Effect. " According to the positions of sustaining cues, they played different actions in this perception, and they are classified into three types: front sustaining cues, side sustaining cues and back sustaining cues. In addition, dynamic fusion and separation of volumetrical illusory objects were perceived when the visual stimuli were moving continuously between two structurally different conditions. Then the hysteresis was recognized in geometrical position between the fusion and separation. The authors believe that the occlusion cues and sustaining cues introduced in this paper could be effective clues for exploiting the new techniques for 3-D display.

In this paper, the use of optimal Karhunen-Loeve (KL) transform for quantization of speech line spectrum frequency (LSF) coefficients is studied. Both scalar quantizer (SQ) and vector quantizer (VQ) schemes are developed to encode efficiently the transform parameters after operating one or two-dimensional KL transform. Furthermore, the SQ schemes are also combined with entropy coding by using Huffman variable length coding (VLC). The basic idea in developing these schemes is utilizing the strong correlation of LSF parameters to reduce the bit rate for a given level of fidelity. Since the use of global statistics for generating the coding scheme may not be appropriate, we propose several adaptive KL transform systems (AKL) to encode the LSF parameters. The performance of all systems for different bit rates is investigated and adequate comparisons are made. It is shown that the proposed KL transform coding systems introduce as good as or better performance for both SQ and VQ in the examined bit rates compared to other methods in the field of LSF coding.

In this paper, a technique to reduce the overhead of Vector Quantization (VQ) coding is developed here. Our method exploits the inter-index correlation property to reduce the overhead to transmit encoded indices. Discrete Cosine Transform (DCT) is the tool to decorrelate the above correlation to get further bit rate reduction. As we know, the codewords in the codebook that generated from conventional LBG algorithm do not have any specified orders. Hence, the indices for selected codewords to represent respective adjacent blocks are random distributions. However, due to the homogeneous property existing among adjacent regions in original image, we re-arrange the codebook according to our predefined weighting criterion to enable the selected neighboring indices capable of indicating the homogeneous feature as well. Then, DCT is used to compress those VQ encoded indices. Because of the homogeneous characteristics existing among the selected adjacent indices after codebook permutation, DCT can achieve better compression efficiency. However, as we know, DCT introduces distortion by the quantization procedure, which yield error-decoded indices. Therefore, we utilize an index residue compensation method to make up that error decoded indices which have high complexity deviation to reduce those unpleasant visual effects caused by distorted indices. Statistics illustrators and table are addressed to demonstrate the efficient performance of proposed method. Experiments are carried out to Lena and other natural gray images to demonstrate our claims. Simulation results show that our method saves more than 50% bit rate to some images while preserving the same reconstructed image qualities as standard VQ coding scheme.

The minimum mean-squared error (MMSE) linear detector has been proposed to successfully suppress the multiple access interference and mitigate the near-far problem in direct-sequence code-division multiple access communication systems. In the presence of unknown or time-varying channel parameters, the MMSE linear detector can be implemented by the blind Griffiths' algorithm, which uses the desired signal vector instead of a training sequence of symbols for initial adaptation. In this paper, a variable step-size (VSS) Griffiths' algorithm is proposed for accelerating the convergence speed, especially in the presence of strong interference. Numerical results show that the convergence properties of the VSS Griffiths' algorithm are robust against the wide eigenvalue-spread problem of the correlation matrix associated with the received signal vector compared to the Griffiths' algorithm using a fixed step-size.

We study some sufficient conditions of codeword lengths for the existence of a fix-free code. Ahlswede et al. proposed the 3/4 conjecture that Σi=1n a-li 3/4 implies the existence of a fix-free code with lengths li when a=2 i. e. the alphabet is binary. We propose a more general conjecture, and prove that the upper bound of our conjecture is not greater than 3/4 for any finite alphabet. Moreover, we show that for any a2 our conjecture is true if codeword lengths l1,l2,. . . consist of only two kinds of lengths.

In this paper, we apply the discrete wavelet transform (DWT) and the discrete wavelet packet transform (DWPT) with the Daubechies wavelet of order 16 to effectively solve for the electromagnetic scattering from a one-dimensional inhomogeneous slab. Methods based on the excitation vector and the [Z] matrix are utilized to sparsify an MoM matrix. As we observed, there are no much high frequency components of the field in the dielectric region, hence the wavelet coefficients of the small scales components (high frequency components) are very small and negligible. This is different from the case of two-dimensional scattering from perfect conducting objects. In the excitation-vector-based method, a modified excitation vector is introduced to extract dominant terms and achieve a better compression ratio of the matrix. However, a smaller compression ratio and a tiny relative error are not obtained simultaneously owing to their deletion of interaction between different scales. Hence, it is inferior to the [Z]-matrix-based methods. For the [Z]-marix-based methods, our numerical results show the column-tree-based DWPT method is a better choice to sparsify the MoM matrix than DWT-based and other DWPT-based methods. The cost of a matrix-vector multiplication for the wavelet-domain sparse matrix is reduced by a factor of 10, compared with that of the original dense matrix.

This paper presents an improved method of speaker verification using the sequential probability ratio test (SPRT), which can treat the correlation between successive feature vectors. The hidden Markov model with the mean field approximation enables us to consider the correlation in the SPRT, i. e. , using the mean field of previous state, probability computation can be carried out as if input samples were independent each other.

A distributed congestion avoidance scheme, the End-to-End Rate Control Algorithm (EERCA), has been proposed for Available Bit Rate (ABR) service. In this work, we enhance EERCA by replacing the Queue Occupancy Reduction with the queuing delay control (QDC), which manipulates the queue occupancy more efficiently with less functional complexity. Furthermore, it alleviates per-VC accounting requirement and thus reduces the complexity of a switch. From both the analysis and the simulation, it shows that the proposed virtual queue occupancy precisely reflects the variation of the actual queue occupancy. This enhanced EERCA features higher efficiency and more stable queue occupancy than the original algorithm.

In this paper, fast algorithms for the CMA (constant modulus algorithm), which is one of the widely used algorithms for blind equalizationi are presented. We propose the FBCMA (frequency domain block CMA) which takes advantage of fast linear convolution in the DFT domain by using the overlap save method. For the FBCMA, a nonlinear error function in the frequency domain is derived using Parseval's relation. Also, an adaptive algorithm in the DFT domain is introduced to adjust the frequency domain filter coefficients. For a block size and filter length of N, the multiplications required for the conventional CMA and proposed FBCMA are on the order of O(N2) and O(N log N), respectively.

We have realized excellent viewing angle characteristics for the π cell, by combining a discotic negative birefringence film, which has a hybrid alignment structure, and a positive a-plate. The negative birefringence of the film completely compensates the positive birefringence of the π cell liquid crystals in the dark-state. The roll of a c-plate, which should be accompanied by the a-plate to suppress the light leakage from crossed polarizer at oblique incident angles, was substituted for the vertically aligned component of the π cell liquid crystal. Taking into account the fast electrooptical response, which is one order faster than that of the twisted-nematic liquid-crystal display, the π cell is one of the most promising liquid-crystal-display modes.

In this paper, we investigate an inherent noise reduction characteristic of a modulated orthogonal sequence. The modulated orthogonal sequence generates length N2 sequences from N information symbols. Using the amplitudes of received sequences, we first estimate the smallest amplitude noise. Then the noise is reduced by the proposed scheme. The noise reduction scheme is shown to have an excellent performance in non-Gaussian noise environment.

In this paper, we show that the principle of quantum cryptography can be applied not only to a key distribution scheme but also to a data transmission scheme. We propose a secure data transmission scheme in which an eavesdropping can be detected based on sharing the bases Alice (the sender) and Bob (the receiver) have. We also show properties of this scheme.

Synchronization and continuity are essential for multimedia presentation, but because network resources and available bandwidth are both limited, synchronization quality and continuity quality have to be traded off in response to the fluctuating network conditions. This paper therefore introduces an algorithm for intramedia synchronization with adaptive quality of service (QoS) control handled at different layers of multimedia streams. The work described here is an extension of our earlier proposal of a synchronization algorithm by delay compensation protocol with two resynchronization mechanisms: retrieval offset adjustment and data unit skipping. That algorithm has been extended by the introduction of QoS control mechanisms in the QoS plane of a distributed control platform. The extended approach results not only in better synchronization and continuity, but also integrates the QoS adjustment into the existing architecture. Unexpected QoS variations are coped with by an adaptive QoS control designed to maintain the desired application qualities within the fluctuating environment. Simulations implemented on a UDP/IP network have verified the effectiveness of the proposed scheme.

Recently, the quantum information theory attracts much attention. In quantum information theory, the existence of superadditivity in capacity of a quantum channel was foreseen conventionally. So far, some examples of codes which show the superadditivity in capacity have been clarified. However in present stage, characteristics of superadditivity are not still clear up enough. The reason is as follows. All examples were shown by calculating the mutual information by quantum combined measurement, so that one had to solve the eigenvalue and the eigenvector problems. In this paper, we construct a simplification algorithm to calculate the mutual information by using square-root measurement as decoding process of quantum combined measurement. The eigenvalue and the eigenvector problems are avoided in the algorithm by using group covariancy of binary linear codes. Moreover, we derive the analytical solution of the mutual information for parity check codes with any length as an example of applying the simplification algorithm.

A new UEP technique for image transmission using trellis code based on Hamming distance criterion has been proposed. The simulation results comparing the image quality and bit-rate for UEP and EEP have been provided. The results show that UEP performs better than EEP in terms of bit-rate without any significant depreciation in image quality.

An analog vector quantization processor has been designed based on the neuron-MOS (νMOS) technology. In order to achieve a high integrating density, template information is merged into the matching cell (the absolute value circuitry) using the νMOS ROM technology. A new-architecture νMOS winner-take-all (WTA) circuit is employed for fully-parallel search for the minimum-distance vector. The WTA performs multi-resolution winner search with an automatic feedback gain control. A test chip having 256 16-element fixed template vectors has been built in a 1.5-µm double-polysilicon CMOS technology with the chip size of 7.2 mm 7.2 mm, and the basic operation of the circuits has been demonstrated.

We propose a hysteresis neural network system solving NP-Hard optimization problems, the N-Queens Problem. The continuous system with binary outputs searches a solution of the problem without energy function. The output vector corresponds to a complete solution when the output vector becomes stable. That is, this system does never become stable without satisfying the constraints of the problem. Though it is very hard to remove limit cycle completely from this system, we can propose a new method to reduce the possibility of limit cycle by controlling time constants.

The MPEG video coding is the most widely used video coding standard which usually generates variable bitrate (VBR) data streams. Although ATM can deliver VBR traffic, the burst traffic still has the possibility to be dropped due to network congestion. The cell loss can be minimized by using an enforced rate control method. However, the quality of the reproduced video may be sacrificed due to insufficient peak rate available. In this work, we propose an end-to-end quality adaptation mechanism for MPEG traffic over ATM. The adaptive quality control (AQC) scheme allocates a certain number of coding bits to each video frame based on the network condition and the type of next frame. More bits may be allocated if the network condition, represented by the connection-level, is good or the next frame is B-frame that usually consumes fewer bits. A high connection-level allows a relatively large number of tagged cells, which are non-guaranteed in delivery, for video frames with high peak rates. The connection-level adjustment unit at the encoder end adjusts the connection-level based on the message of the network condition from the quality monitoring unit at decoder. The simulation results show that the AQC system can effectively utilize the channel bandwidth as well as maintain satisfactory video quality in various network conditions.

We analyze the dynamics of self-organizing cortical maps under the influence of external stimuli. We show that if the map is a contraction, then the system has a unique equilibrium which is globally asymptotically stable; consequently the system acts as a stable encoder of external input stimuli. The system converges to a fixed point representing the steady-state of the neural activity which has as an upper bound the superposition of the spatial integrals of the weight function between neighboring neurons and the stimulus autocorrelation function. The proposed theory also includes nontrivial interesting solutions.

Since the proposal of differential cryptanalysis and linear cryptanalysis in 1991 and 1993, respectively, the resistance to these cryptanalysis has been studied. In FSE2, Knudsen proposed a method of attacking block ciphers that used the higher order differential, and in FSE4, Jakobsen and Knudsen applied it to a cipher proposed by Nyberg and Knudsen. Their approach, however, requires large complexity of running time. In this paper, we improve this attack and show that our improved algorithm requires much fewer chosen texts and much less complexity than those of previous works.