In this study, a modeling method of the intermittency chaos using the Markov chain is proposed. The performances of the intermittency chaos and the Markov chain model are investigated when they are injected to the Hopfield Neural Network for a quadratic assignment problem or an associative memory. Computer simulated results show that the proposed modeling is good enough to gain similar performance of the intermittency chaos.

Finding DC operating points of transistor circuits is an important and difficult task. The Newton-Raphson method adopted in SPICE-like simulators often fails to converge to a solution. To overcome this convergence problem, homotopy methods have been studied from various viewpoints. For efficiency of globally convergent homotopy methods, it is important to give an appropriate initial solution as a starting point. However, there are few studies concerning such initial solution algorithms. In this paper, initial solution problems in homotopy methods are discussed, and an effective initial solution algorithm is proposed for globally convergent homotopy methods, which finds DC operating points of transistor circuits efficiently. Numerical examples using practical transistor circuits show the effectiveness of the proposed algorithm.

We have developed a high-efficiency charge-pump power supply circuit with large output current capability for mobile equipment. However, during the commercialization phase, we found that the large inrush current of 270 mA at charge-pump circuit startup-time could cause problems. In this paper we analyze the mechanism that causes this inrush current, and we propose circuitry to reduce it. We show SPICE simulation and measurement results for our proposed circuitry that confirm its effectiveness. By incorporating this circuitry, startup-time inrush current was reduced to 30 mA.

This paper presents a technique for improving the SNR and resolution of complex bandpass ΔΣADCs which are used for wireless communication systems such as cellular phone, wireless LAN and Bluetooth. Oversampling and noise-shaping are used to achieve high accuracy of a ΔΣAD modulator. However when a multi-bit internal DAC is used inside a modulator, nonlinearities of the DAC are not noise-shaped and the SNR of the ΔΣADC degrades. For the conversion of complex intermediate frequency (IF) input signals, a complex bandpass ΔΣAD modulator can provide superior performance to a pair of real bandpass ΔΣAD modulators of the same order. This paper proposes a new noise-shaping algorithm--implemented by adding simple digital circuitry--to reduce the effects of nonlinearities in multi-bit DACs of complex bandpass ΔΣAD modulators. We have performed simulation with MATLAB to verify the effectiveness of the algorithm, and the results show that the proposed algorithm can improve the SNR of a complex bandpass ΔΣADC with nonlinear internal multi-bit DACs.

In this paper, we propose the CMOS implementation of a multiple-valued memory cell using -shaped negative-resistance devices. We first propose the construction of a multiple-stable circuit that consists of -shaped negative-resistance devices from four enhancement-mode MOSFETs without a floating voltage source, and connect this in parallel with a unit circuit. It is shown that the movement of -shaped negative-resistance characteristics in the direction of the voltage axis is due to voltage sources. Furthermore, we propose the construction of a multiple-valued memory cell using a multiple-stable circuit. It is shown that it is possible to write and hold data. If the power supply is switched on, it has a feature which enables operation without any electric charge leakage. It is possible, by connecting -shaped negative-resistance devices in parallel, to easily increase the number of multiple values.

A multiple channel active noise control (ANC) system with several secondary sources, error sensors, and reference sensors has been used for complicated noise fields. Centralized multiple channel ANC systems have been proposed, however implementation of such systems becomes difficult according to increase of control points. Distributed multiple channel ANC systems which have more than a controller are considered. This paper proposes a new implementation of distributed multiple channel ANC systems based on simultaneous equations methods. In the proposed algorithm, communications between controllers are permitted to distribute the computational burden and to improve the performance of noise reduction. This algorithm shows good performances for noise cancellation and tracking of changes in the error paths.

A scheme of error correction for JPEG2000 codestream is proposed in this paper. The scheme uses a forward error correction code (FEC) and a data hiding technique. The headers and the higher quality layers of the codestream are coded using FEC codes. Then the parity data are separated from the FEC-coded data and hidden in the JPEG2000 codestream. The hidden data are used for error correction at the decoder. Several error correction codes with different strength are selected for the main header, the tile-part headers, the packet headers, and the bodies. The codestream generated by the proposed scheme has backward compatibility with a standard JPEG2000 codestream. Thus, it can be decoded with a general decoder. Simulation results demonstrated the effectiveness of the proposed scheme.

This paper proposes an instruction-level power estimation method for an embedded RISC processor, the power consumption of which fluctuates so much by applications and input data. The proposed method estimates the power consumption from the result of ISS (Instruction Set Simulator) and energy tables according to Hamming Distance of Registers (HDR) of all instructions. It is over 10⁵ times faster than the gate-level detailed logic simulation, while the estimated power curves have the same tendency with those from the logic simulation. The proposed method realizes both accurate and fast power estimation of embedded processors.

This paper proposes a hardware/software cosynthesis algorithm for processors with heterogeneous registers. Given a CDFG corresponding to an application program and a timing constraint, the algorithm generates a processor configuration minimizing area of the processor and an assembly code on the processor. First, the algorithm configures a datapath which can execute several DFG nodes with data dependency at one cycle. The datapath can execute the application program at the least number of cycles. The branch and bound algorithm is applied and all the number of functional units and memory banks are tried. For an assumed number of functional units and memory banks, an appropriate number of heterogeneous registers and connections to functional units and registers are explored. The experimental results show effectiveness and efficiency of the algorithm.

In this paper, we propose a synthesis method of hybrid systems with specified limit cycles. Several methods which sysnthesize a nonlinear system with prescribed limit cycles have been proposed. In these methods, the limit cycle is given by an algebraic equation, which will be called constraint equations, and its stability is guaranteed by a Lyapunov function derived from the constraint equation. In general, limit cycles of hybrid systems are nonsmooth due to the discontinuous vector fields. So the limit cycles are given by piecewise smooth constraint equations, we employ the piecewise smooth Lyapunov functions to construct desired nonsmooth limit cycles and guarantee their stability.

The PLC (Programmable Logic Controller) has been widely used in the industrial world as a controller for manufacturing systems, as a process controller and so on. The conventional PLC has been designed and verified as a pure Discrete Event System (DES) by using an abstract model of a controlled plant. In verifying the PLC, however, it is also important to take into account the physical behavior (e.g. dynamics, shape of objects) of the controlled plant in order to guarantee such important factors as safety. This paper presents a new verification technique for the PLC-based control system, which takes into account these physical behaviors, based on a Hybrid Dynamical System (HDS) framework. The other key idea described in the paper is the introduction of the concept of signed distance which not only measures the distance between two objects but also checks whether two objects interfere with each other. The developed idea is applied to illustrative material handling problems, and its usefulness is demonstrated.

In this paper, we study supervisory control of a class of discrete event systems with simultaneous event occurrences, which we call concurrent discrete event systems. The behavior of the system is described by a language over the simultaneous event set. We introduce a notion of concurrent well-posedness of languages. We then prove that L_m(G)-closure, controllability, and concurrent well-posedness of a specification language are necessary and sufficient conditions for the existence of a nonblocking supervisor. We address the computational complexity for verifying the existence conditions.

An IIR digital low pass filter with flat monotonic passband, equiripple stopband and narrower transition bandwidth than that of Inverse Chebyshev digital filters of the same order is designed. The requisite equiripple stopband is realized by designing the filter in Deczkeys' w-plane. The characteristic functions are designed so as to have a root of multiplicity n at ω = 0 to ensure the n degree of flatness of the passband, and to have a pair of complex conjugate roots with coordinates constrained such that the magnitude response of the passband attenuates monotonically. The freedom in the coordinate of the complex conjugate roots is exploited to minimize the transition bandwidth. The equations are derived that give the minimum transition bandwidth of the proposed filter, which is considerably narrower than that of Inverse Chebyshev filters. It is showen through practical numerical examples that the order of the proposed filter is as low as half that of the Inverse Chebyshev filter satisfying the same specification.

The paper discusses the spatio-temporal phenomena in autonomous two-layer Cellular Neural Networks (CNNs) with mutually coupled templates between two layers. By computer calculations, we show how pattern formations, autowaves and classical waves can be regenerated in the networks, and describe the properties of these phenomena in detail. In particular, we focus our discussion on the necessary conditions for generating these spatio-temporal phenomena. In addition, the influences of the template parameters and initial state conditions of CNNs on the spatio-temporal phenomena are investigated.

In this paper, we introduce the following m-layered hard constrained convex feasibility problem HCF(m): Find a point u _m, where ₀:=H (a real Hilbert space), _i: = arg min g_i(_i-1) and g_i(u):=w_i,jd ²(u,C_i,j) are defined for (i) nonempty closed convex sets C_i,jH and (ii) weights w_i,j > 0 satisfying w_i,j=1 (i {1,,m}, j {1,,M_i}. This problem is regarded as a natural extension of the standard convex feasibility problem: find a point u C_i, where C_i H (i {1,, M}) are closed convex sets. Unlike the standard problem, HCF(m) can handle the inconsistent case; i.e., _i,j C_i,j = , which unfortunately arises in many signal processing, estimation and design problems. As an application of the hybrid steepest descent method for the asymptotically shrinking nonexpansive mapping, we present an algorithm, based on the use of the metric projections onto C_i,j, which generates a sequence (u_n) satisfying lim_n d(u_n,₃) = 0 (for M₁ = 1) when at least one of C_1,1 or C_2,j's is bounded and H is finite dimensional. An application of the proposed algorithm to the pulse shaping problem is given to demonstrate the great flexibility of the method.

Although watermarking techniques have been extensively developed for natural videos, little progress is made in the area of graphics animation. Following the former successful MPEG-1 and MPEG-2 coding standards that provide efficient representations of natural videos, the emerging MPEG-4 standard incorporates new coding tools for 2D mesh animation. Graphics animation information is crucial for many applications and may need proper protection. In this paper, we develop a watermarking technique suitable for MPEG-4 2D mesh animation. The proposed method is based on the multiresolution analysis of 2D dynamic mesh. We perform wavelet transform on the temporal sequence of the node points to extract the significant spectral components of mesh movement, which we term the "feature motions. " A binary watermark invisibly resides in the feature motions based on the spread-spectrum principle. Before watermark detection, a spatial-domain least-squares registration technique is used to restore the possibly geometrically distorted mesh data. Each watermark bit is then detected by hard decision with cryptographically secure keys. We have tested the proposed method with a variety of attacks, including affine transformations, temporal smoothing, spectral enhancement and attenuation, additive random noise, and a combination of the above. Experimental results show that the proposed watermarks can withstand the aforementioned attacks.

This paper formulates functions generating four kinds of binary sequence sets of length 2ⁿ with zero correlation zone, which have been discussed for approximately synchronized CDMA systems without co-channel interference nor influence of multipath. They are logic functions of a binary vector of order n, expressed by EXOR and AND operations.

In this paper, a novel Wold decomposition algorithm is proposed to address the issue of deterministic component extraction for texture images. This algorithm exploits the wavelet-based singularity detection theory to process both harmonic a nd evanescent features from frequency domain. This exploitation is based on the 2D Lebesgue decomposition theory. When applying multiresolution analysis techniq ue to the power spectrum density (PSD) of a regular homogeneous random field, its indeterministic component will be effectively smoothed, and its deterministic component will remain dominant at coarse scale. By means of propagating these positions to the finest scale, the deterministic component can be properly extracted. From experiment, the proposed algorithm can obtain results that satisfactorily ensure its robustness and efficiency.

In this paper, we propose a dynamic bit-rate reduction scheme for transcoding an MPEG-1 bitstream into an MPEG-4 simple profile bitstream with a typical bit-rate of 384 kbps. For dynamic bit-rate reduction, a significant reduction in the bit-rate is achieved by combining the processes of requantization and frame-skipping. Conventional requantization methods for a homogeneous transcoder cannot be used directly for a heterogeneous transcoder due to the mismatch in the quantization parameters between the MPEG-1 and MPEG-4 syntax and the difference in the compression efficiency between MPEG-1 and MPEG-4. Accordingly, to solve these problems, a new requantization method is proposed for an MPEG-1 to MPEG-4 transcoder consisting of R-Q (rate-quantization) modeling with a simple feedback and an adjustment of the quantization parameters to compensate for the different coding efficiency between MPEG-1 and MPEG-4. For bit-rate reduction by frame-skipping, an efficient method is proposed for estimating the relevant motion vectors from the skipped frames. The conventional FDVS (forward dominant vector selection) method is improved to reflect the effect of the macroblock types in the skipped frames. Simulation results demonstrated that the proposed method combining requantization and frame-skipping can generate a transcoded MPEG-4 bitstream that is much closer to the desired low bit-rate than the conventional method along with a superior objective quality.

Watermarking schemes have been extensively discussed and developed recently. People are usually facing the dilemma of two factors, robustness and transparency. To achieve these requirements, embedding the watermark message in the transform domain or the spatial domain is usually considered. In this paper, we will propose a blind image watermarking scheme based on vector quantization. By exploiting a modified binary tree splitting method, a stable codebook could be generated so that the watermark message could be novelly embedded and survive the JPEG compression and the Gaussian noise addition. The embedded message could be extracted without referring the host image. It makes the scheme more practical.

In this paper, we present a novel energy compaction method, called the selective block-wise reordering, which is used with SPIHT (SBR-SPIHT) coding for low rate video coding to enhance the coding efficiency for motion-compensated residuals. In the proposed coding system, the motion estimation and motion compensation schemes of H.263 are used to reduce the temporal redundancy. The residuals are then wavelet transformed. The block-mapping reorganization utilizes the wavelet zerotree relationship that jointly presents the wavelet coefficients from the lowest subband to high frequency subbands at the same spatial location, and allocates each wavelet tree with all descendents to form a wavelet block. The selective multi-layer block-wise reordering technique is then applied to those wavelet blocks that have energy higher than a threshold to enhance the energy compaction by rearranging the significant pixels in a block to the upper left corner based on the magnitude of energy. An improved SPIHT coding is then applied to each wavelet block, either re-ordered or not. The high energy compaction resulting from the block reordering can reduce the number of redundant bits in the sorting pass and improve the quantization efficiency in the refinement pass of SPIHT coding. Simulation results demonstrate that SBR-SPIHT outperforms H.263 by 1.28-0.69 dB on average for various video sequences at very low bit-rates, ranging from 48 to 10 kbps.

This paper proposes a new steganographic method utilizing features of JPEG compression. The method embeds secret information using the number of zeroes in a block of quantized DCT coefficients in minimum coding units (MCU) of JPEG images. In the method, we can embed secret information into JPEG images with degradation like that by JPEG compression. Furthermore, the method causes little change of the histogram of quantized DCT coefficients, so it is hard to perceive secret information embedded by the method. The method mainly modifies boundaries between zero and non-zero DCT coefficients, so we can use the low frequency side of DCT coefficients for another steganographic method.

In this paper, performance of chaos and burst noises injected to the Hopfield Neural Network for quadratic assignment problems is investigated. For the evaluation of the noises, two methods to appreciate finding a lot of nearly optimal solutions are proposed. By computer simulations, it is confirmed that the burst noise generated by the Gilbert model with a laminar part and a burst part achieved the good performance as the intermittency chaos noise near the three-periodic window.

A new speaker feature extracted from multi-wavelet decomposition for speaker recognition is described. The multi-wavelet decomposition is a multi-scale representation of the covariance matrix. We have combined wavelet transform and the multi-resolution singular value algorithm to decompose eigenvector for speaker feature extraction not at the square matrix. Our results have shown that this multi-wavelet feature introduced better performance than the cepstrum and Δ-cepstrum with respect to the percentages of recognition.

This letter presents a novel quandtree-based image authentication technique especially suitable for the content authentication of high quality required digital images. The host image and the hiding marks generate quadtrees which record the information of host images. Any malicious tamper to the image is reflected from the recovered marks. Compared to other authentication schemes based on the fragile watermarking technique, the host image is not at all modified and the detection to malicious tamper is sensitive.

A watermarking system is secure as long as it satisfies Kerckhoffs principle according to the cryptography. In this letter, two novel techniques named the encrypted orthogonal transformation and its improved scheme as useful preprocessing methods are presented to apply to the watermarking field, which can enhance the security of the watermarking scheme. Compared to discrete cosine transform watermarking algorithms, this method has similar robustness but higher security.

A compact, low voltage, low power and wide output operating range CMOS exponential-control variable-gain amplifier has been presented. The gain control range of the proposed variable-gain amplifier can be about 50.7 dB while the maximum linearity error is about -1.09%. For the case of supply voltage V_DD = 2 V, the maximum power dissipation is only 1.6 µW. The proposed circuit has been fabricated in a 0.5 µm 2p2m N-well CMOS process. Experimental results are given to confirm the feasibility of the proposed variable gain amplifier. The proposed circuit is expected to be useful in analog signal processing applications.

Recently, Kuwakado and Tanaka proposed a transitive signature scheme for directed trees. In this letter, we show that Kuwakado-Tanaka scheme is insecure against a forgery attack, in which an attacker is able to forge edge signatures by composing edge signatures provided by a signer.

A method for estimating the bit-error rate (BER) of turbo codes called the Monte Carlo distance spectrum method is proposed. Testing this method shows that the estimated BER curves closely approximate the results of a Monte Carlo simulation.

A novel fast KNN classification algorithm is proposed for pattern recognition. The technique uses one important feature, mean of the vector, to reduce the search space in the wavelet domain. Since the proposed algorithm rejects those vectors that are impossible to be the k closest vectors in the design set, it largely reduces the classification time and holds the classification performance as that of the original classification algorithm. The simulation on texture image classification confirms the efficiency of the proposed algorithm.

In texture mapping, anisotropic filtering methods, which require more texels, have been proposed for high-quality images. Memory bandwidth, however, is still limited by a bottleneck in the texture-filtering hardware. In this paper, we propose anisotropic texture filtering based on edge function. In generating the weight that plays a key role in filtering texels loaded from memory, the edge function gives accurate contribution of texels to the pixel intensity. The quality of images is superior to other methods. For images of the same quality, our method requires less than half the texels of other methods. In other words, the improvement in performance is more than twice that of other methods.