Although production systems are widely used in artificial intelligence (AI) applications, they are seen to have certain disadvantages in terms of their need for special purpose assistance software to build and execute their knowledge-bases (KB), and in the fact that they will not run on any operating system (platform dependency). Furthermore, for AI applications such as learning assistance systems, there is a strong requirement for a self-adaptive function enabling a flexible change in the service contents provided, according to the user. Against such a background, a Java based production system (JPS) featuring no requirement for special purpose assistance software and no platform dependency, is proposed. Furthermore, a new self-adaptive Java production system (A-JPS) is proposed to realize the "user adaptation" requirement mentioned above. Its key characteristic is the combination of JPS with a Causal-network (CN) for obtaining a "user profile". In addition, the execution time of the JPS was studied using several benchmark problems with the aim of comparing the effectiveness of different matching algorithms in their recognize-act cycles as well as comparing their performance to that of traditional procedural programs for different problem types. Moreover, the effectiveness of the user adaptation function of the A-JPS was studied for the case of a CN with a general DAG structure, using the experimental KB of a learning assistance system.

An efficient way to optimize the hardware consumption in a low-voltage ΔΣ modulator for D/A converters is described. The modulator employs a ROM selection scheme for multiplications and the new buffer-and-routing ROM structure to minimize the hardware consumption. Furthermore, a guideline of the power-delay-and-area product (PDAP) for compelling issues such as power dissipation, delay time, and chip area consumption in the modern digital-circuit design is proposed. After the validity of the concept has been proved in comparison with that of the conventional guideline of the power-delay product in several behavioral blocks, it was employed in the circuit design. Fabricated in a standard digital 0.35-µm CMOS technology, the modulator achieves a signal-to-noise ratio (SNR) of 96 dB with an oversampling ratio of 256 under the supply of 2.0 V.

Because of the polarization dependencies of optical fiber transmission equipment, the polarization state of lightwaves inherently varies at the optical receiver input. Therefore the receiver output, especially the beat component, is very dependent on the polarization state. We derive a simple relation showing that the beat power of the lightwaves is proportional to the inner product of their Stokes vectors. Using this relation, we can systematically calculate the beat power. This calculation method can be applied to lightwaves of arbitrary polarization, such as a polarization-scrambled signal or partially polarized amplified spontaneous emission (ASE) in long-haul IM/DD systems, as well as to the signal and local oscillator lightwaves of coherent systems.

In this paper, a simple and practical corresponding-color reproduction model based on the chromatic adaptation of the human visual system (HVS), named a modified von Kries chromatic-adaptation model, is proposed for TV and PC monitors under a variety of viewing conditions. We derived the proposed corresponding-color reproduction model based on Breneman's corresponding-color data. The proposed model has a 1-2% less error than Fairchild's and Breneman's model, 11.5% less error than von Kries' model and 60% less error than CIECAM97s' model in terms of color reproduction errors, (). Also, these tendency is similar in color reproduction errors, . We implemented a corresponding-color reproduction system using the proposed model under a variety of viewing conditions. For the determination of viewing conditions, illuminant correlated color temperatures (CCTs) are measured by yellow/cyan sensors. These measured surround illuminant CCTs can estimate an adaptated neutral point of the HVS in TV viewing conditions. Experiments were carried out to assess the proposed model performance in terms of color fidelity by comparing complex images on a LCD monitor under illuminants from 2500 K to 7500 K. We confirmed that the implemented system using the proposed model can predict corresponding-color data very well under a variety of viewing conditions. Therefore, by applying the proposed model and system to the LCD, the reproduction colors viewed in real surrounding viewing conditions on the LCD could appear the same as the original object colors under standard viewing conditions. Furthermore, they could be applied to any other color display device such as a CRT, a PDP, and a DLP in order to get better reproduction colors.

We present a speaker adaptation method that makes it possible to determine articulatory parameters from an unknown speaker's speech spectrum using an HMM (Hidden Markov Model)-based speech production model. The model consists of HMMs of articulatory parameters for each phoneme and an articulatory-to-acoustic mapping that transforms the articulatory parameters into a speech spectrum for each HMM state. The model is statistically constructed by using actual articulatory-acoustic data. In the adaptation method, geometrical differences in the vocal tract as well as the articulatory behavior in the reference model are statistically adjusted to an unknown speaker. First, the articulatory parameters are estimated from an unknown speaker's speech spectrum using the reference model. Secondly, the articulatory-to-acoustic mapping is adjusted by maximizing the output probability of the acoustic parameters for the estimated articulatory parameters of the unknown speaker. With the adaptation method, the RMS error between the estimated articulatory parameters and the observed ones is 1.65 mm. The improvement rate over the speaker independent model is 56.1 %.

The utilization of EXOR gates often decreases the number of gates needed for realizing practical logical networks, and enhances the testability of networks. Therefore, logic synthesis with EXOR gates has been studied. In this paper we propose a new logic representation: an ESPP (EXOR-Sum-of-Pseudoproducts) form based on pseudoproducts. This form provides a new three-level network with EXOR gates. Some functional classes in ESPP forms can be realized with shorter expressions than in conventional forms such as the Sum-of-Products. Since many practical functions have the properties of such classes, the ESPP form is useful for making a compact form. We propose a heuristic minimization algorithm for ESPP, and we demonstrate the compactness of ESPPs by showing our experimental results. We apply our technique to some logic function classes and MCNC benchmark networks. The experimental results show that most ESPP forms have fewer literals than conventional forms.

Recent investigations using magnetic resonance imaging (MRI) of human speech organs have opened up new avenues of research. Visualization of the speech production system provides abundant information on the physiological and acoustic realization of human speech. This article summarizes the current status of MRI applications with respect to speech research as well as our own experience of discovery and re-evaluation of acoustic events emanating from the vocal tract and physiological mechanisms.

Rate compatible (RC) codes are used for adaptive coding schemes or hybrid ARQ schemes in order to adapt varying channel conditions. This can improve overall service quality or the system throughput. Conventional RC codes have usually been designed on the basis of convolutional codes. This letter proposes an efficient RC code based on block codes. We use a high dimensional product code and divide it into the information block and a number of parity blocks. We form RC product codes using various combinations of these blocks. Because we can decode the RC product codes iteratively, these result in block turbo codes and they can be used efficiently for hybrid ARQ schemes.

This study addresses the problem of computing the reliability of stochastic binary systems. This computational problem is known as the problem of the union of a set of events, where each event is expressed as the product of a set of Boolean variables. It is assumed that each Boolean variable may take on either of two states: operative or failed. Computing the reliability of stochastic binary systems is known to be #P-complete. The computation remains #P-complete, even when all events have a cardinality two, and both elements of each event are selected from two disjoint sets. This study proposes a linear time algorithm to compute the reliability of stochastic binary systems when the events satisfy specific requirements.

Software reuse has been recognized as important. According to our research, when a software product is reused, products correlated to the reused one may be reusable. This paper proposes a model for software products and a technique to retrieve correlated products. The paper also presents equations to evaluate correlation values, which is guidance for selecting reusable correlated products. Since correlated products can be identified by tracing product relationships, the proposed model manages both products and relationships.

Large number of electronic connectors are widely used in various electronic and telecommunication systems. No matter whether it is optical telecommunications or mobile phone systems, connectors are important links for electronics. Unfortunately connector contacts are exposed in air, they are different from any other electronic components, the contacts are greatly influenced by the environment where they operate. In China, dust and corrosion products are the main contaminants to cause contact failure. Evidently the failed contacts seriously deteriorate the reliability of electronic and telecommunication systems. This paper summarizes the recent achievements obtained by our Lab on the effect of dust and corrosion products to the connector contact failure. Since dust contamination is a very complex problem which is not only popular in China, but also happened in many countries. Continuous studies will be very useful to improve the contact reliability of connectors, setting up new and effective testing methods and standards, building up experimental and computer simulation systems.

Obtaining a linearizing feedback and a coordinate transformation map is very difficult, even though the system is feedback linearizable. It is known that finding a desired transformation map and feedback is equivalent to finding an integrating factor for an annihilating one-form for single input nonlinear systems. It is also known that such an integrating factor can be approximated using the simple C.I.R method and tensor product splines. In this paper, it is shown that m integrating factors can always be approximated whenever a nonlinear system with m inputs is feedback linearizable. Next, m zero-forms can be constructed by utilizing these m integrating factors and the same methodology in the single input case. Hence, the coordinate transformation map is obtained.

Decreased power dissipation and transient voltage drops in CMOS power distribution networks are important for high-speed deep submicrometer CMOS integrated circuits. In this paper, three CMOS buffers based on the charge-transfer, split-path and bootstrapped techniques to reduce the power dissipation and transient voltage drop in power supply are proposed. First, the inverted-delay-unit is used in the low-power inverted-delay-unit (LPID) CMOS buffer to eliminate the short-circuit current of the output stage. Second, the low-swing bootstrapped feedback-controlled split-path (LBFS) CMOS buffer is proposed to eliminate the short-circuit current of the output stage by using the feedback-controlled split-path method. The dynamic power dissipation of the LBFS CMOS buffer can be reduced by limiting the gate voltage swing of the output stage. Moreover, the propagation delay of the LBFS CMOS buffer is also reduced by non-full-swing gate voltage of the output stage. Third, the charge-recovery scheme is used in the charge-transfer feedback-controlled 4-split-path (CRFS) CMOS buffer to recovery and pull up the gate voltage of the output stage for reducing power-delay product and power line noise. Based on HSPICE simulation results, the power-delay product and the transient voltage drop in power supply of the proposed three CMOS buffers can be reduced by 20% to 40% as compared to conventional CMOS tapered buffer under various capacitive load.

This paper describes the effects of system LSI design with C language-based behavioral synthesis following several trials of design period reduction and quality improvement for a variety of circuit types. The results of these trials are analyzed from the viewpoints of description productivity, verification productivity, reusability and design flexibility as well as hardware and software co-verification. First the C-based design flow proposed by the authors is described, and the design productivity and verification productivity under this design flow is compared to RTL design. The reusability of the behavioral IP core and its efficiency with HW/SW co-verification are also shown using design examples. Next, using the example of an MPEG-4 video decoder design, a typical design process in a C-based design is shown with considerations regarding verification efficiency, reusability of the IP core and HW/SW co-verification. Finally, the authors' perspectives regarding future directions of system LSI design are discussed.

A parity check matrix for a binary linear code defines a bipartite graph (Tanner graph) which is isomorphic to a subgraph of a factor graph which explains a mechanism of the iterative decoding based on the sum-product algorithm. It is known that this decoding algorithm well approximates MAP decoding, but degradation of the approximation becomes serious when there exist cycles of short length, especially length 4, in Tanner graph. In this paper, based on the generating idempotents, we propose some methods to design parity check matrices for cyclic codes which define Tanner graphs with no cycles of length 4. We also show numerically error performance of cyclic codes by the iterative decoding implemented on factor graphs derived from the proposed parity check matrices.

This paper presents a new hierarchical scheduling method for a large-scale manufacturing system based on the hybrid Petri-net model, which consists of CPN (Continuous Petri Net) and TPN (Timed Petri Net). The study focuses on an automobile production system, a typical large-scale manufacturing system. At a high level, CPN is used to represent continuous flow in the production process of an entire system, and LP (Linear Programming) is applied to find the optimal flow. At a low level, TPN is used to represent the manufacturing environment of each sub-production line in a decentralized manner, and the MCT algorithm is applied to find feasible semi-optimal process sequences for each sub-production line. Our proposed scheduling method can schedule macroscopically the flow of an entire system while considering microscopically any physical constraints that arise on an actual shop floor.

It has been considered difficult to obtain the minimum AND-EXOR expression of a given function with six variables in a practical computing time. In this paper, a faster algorithm of minimizing AND-EXOR expressions is proposed. We believe that our algorithm can compute the minimum AND-EXOR expressions of any six-variable and some seven-variable functions practically. In this paper, we first present a naive algorithm that searches the space of expansions of a given n-variable function f for a minimum expression of f. The space of expansions are generated by using all combinations of (n-1)-variable product terms. Then, how to prune the branches in the search process and how to restrict the search space to obtain the minimum solutions are discussed as the key point of reduction of the computing time. Finally a faster algorithm is constructed by using the methods discussed. Experimental results to demonstrate the effectiveness of these methods are also presented.

This paper presents an iterative algorithm for decoding product codes based on syndrome decoding of component codes. This algorithm is devised to achieve an effective trade-off between error performance and decoding complexity. A simplified list decoding algorithm, which uses a modified syndrome decoding method, for linear block codes is devised to deliver soft outputs for iterative decoding of product codes. By adjusting the size of the list, the decoder can achieve a proper trade-off between decoding complexity and performance. Compared to the other iterative decoding algorithms for product codes, the proposed algorithm has lower complexity while offers at least the same performance, which is demonstrated by analyses and simulations. The proposed algorithm has been simulated for BPSK and 16-QAM modulations over both the additive white Gaussian noise (AWGN) and Raleigh fading channels. This paper also presents an efficient scheme for applying product codes and their punctured versions. This scheme can be implemented with variable packet size and channel data block.

In loudspeaker-based 3D audio systems, there are some acoustic crosstalk cancellation methods to enlarge the 'sweet spot' around a fixed listener position. However, these methods have common defect that most of them can be applied only to the specific narrow frequency band. In this letter, we propose the more robust acoustic crosstalk cancellation method so that we can cancel the crosstalk signal in far wider frequency band and enlarge 'sweet spot. ' For this goal, we apply a sum and difference filter to the conventional three loudspeaker-based 3D audio system.

We describe a method of compensating temperature fluctuation by a linear-time-warping processing in a sound reproduction system. This technique is applied to impulse responses of room transfer functions, to achieve a high-quality sound reproduction system, particularly one that treats high-frequency components. First, the impulse responses are measured before and after temperature fluctuation, and the former are converted to the latter by the proposed process. Next, we design inverse filters for the system, and evaluate the improvement of the reproduction accuracy and spectrum distortion. By the compensation method, we can improve the reproduction accuracy at any frequency. Moreover, we propose an adaptive algorithm for the estimation of a suitable warping ratio, using the observed signal of reproduced sound obtained at only one control point. Using the proposed algorithm, we can improve the reproduction accuracy at each control point by about 14 dB, in which a difference in temperature is 1.4.