We have developed a new method to improve cooperation in concurrent systems for distributed control by using multi-agent (MA) functions. Since field terminals (FTs) work concurrently, cooperation among them is essential to the effectiveness and efficiency of the overall system. When FTs are modeled as agents, it is easy to explicitly deal with the interactions among them because those interactions can be modeled naturally as communication among agents with cooperation and negotiation. In conventional central control systems, the host computer supervises and controls all FTs in accordance with a pre-installed control algorithm. Our method instead uses intelligent field terminals (IFTs) that can evaluate the diverse information from devices of other IFTs autonomously. In the work reported here, we have evaluated the effectiveness and efficiency of our cooperative control method experimentally and have developed a system using this method to control various kinds of water delivery systems. The IFT providing MA functions that can evaluate the control parameters (CPs) and conditions of the other IFTs. If turn-around time is to be shortened, the conflicts that occur when the data processed by different IFTs is inconsistent or irregular must be resolved autonomously. Each IFT therefore cooperates with diverse functional agents (FA)s of other IFTs by using priority levels, conditions, and evaluation points in order to maintain the continuity of water delivery.

A uniquely parsable grammar (UPG) introduced by Morita et al. is a kind of generative grammar, in which parsing can be performed without backtracking. It is known that UPGs and their three subclasses form the "deterministic Chomsky hierarchy. " In this paper, we introduce three kinds of normal forms for UPGs, i.e., Type-0, Type-1 and Type-2 UPGs by restricting the forms of rules to very simple ones. We show that the upper three classes in the deterministic Chomsky hierarchy can be exactly characterized by the three types of UPGs.

This paper proposes aspiration controls which restrains aspiration branches and keeps the original tabu-based searching by considering past and/or (predicted) future searching profiles. For implementation of the aspiration control we employ not only the short-term and long-term memory but also future memory which is first introduced in this paper as a new concept in the tabu search field. The tabu search with the aspiration control is also parallelized. Moreover two types of parallel cooperative searching scheme are proposed. Through computational experiment, we observe efficiency of our approach comparing to the traditional ones. Especially, we find that cooperative searching has possibility to improve the solution quality very well.

Loop optimization plays an important role in compiler optimization and program transformation. Many sophisticated techniques such as loop-invariance code motion, loop restructuring and loop fusion have been developed. This paper introduces a novel technique called loop quasi-invariance code motion. It is a generalization of standard loop-invariance code motion, but based on loop quasi-invariance analysis. Loop quasi-invariance is similar to standard loop-invariance but allows for a finite number of iterations before computations in a loop become invariant. In this paper we define the notion of loop quasi-invariance, present an algorithm for statically computing the optimal unfolding length in While-programs and give a transformation method. Our method can increase the accuracy of program analyses and improve the efficiency of programs by making loops smaller and faster. Our technique is well-suited as supporting transformation in compilers, partial evaluators, and other program transformers.

We propose a variation of the Context Tree Weighting algorithm for tree source modified such that the growth of the context resembles Lempel-Ziv parsing. We analyze this algorithm, give a concise upper bound to the individual redundancy for any tree source, and prove the asymptotic optimality of the data compression rate for any stationary and ergodic source.

Although a number of car-traffic simulators have been developed for various purposes, none of the existing simulators enhance the simulation accuracy using sensor data or allow the system structure to re-configure the system structure depending on the application. Our goal was to develop a highly accurate, highly modular, flexible, and scalable micro-model car-traffic simulation system. The HLA (High Level Architecture) was applied to every system module as a standard interface between each module. This allows an efficient means for evaluating and validating a variety of micro-model simulation schemes. Our ongoing projects consist of running several identical simulations concurrently, with different parameter sets. By sending the results of these simulations to a manager module, which analyzes both the parameter sets and the simulated results, the manager module can evaluate the best-simulated results and determine the next action by comparing these results with the sensor data. In this system, the sensor data or the statistical data on the flow of traffic, obtained by monitoring real roads, is used to improve the simulation accuracy. Future systems are being planned to employ real time sensor data, where the input of the data occurs at almost real time speed. In this paper, we discuss the design of a HLA-based car-traffic simulation system and the construction of a sensor-data fusion algorithm. We also discuss our preliminary evaluation of the results obtained with this system. The results show that the proposed fusion algorithm can adjust the simulation accuracy to the logged sensor data within a difference of 5% (minimum 1.5%) in a specific time period. We also found that simulations with 500 different parameter sets can be executed within 5 minutes using 8 simulator modules.

The expected lengths of the parsed segments obtained by applying Lempel-Ziv incremental parsing algorithm for i.i.d. source satisfy simple recurrence relations. By extracting a combinatorial essence from the previous proof, we obtain a simpler derivation.

The encoding procedure that allows one to represent integers by binary vectors (codewords) in such a way that addition is replaced with the OR operation applied to these vectors is described. The codeword of the sum is constructed using the decoding algorithm. As a result, many of the transformations can be realized using parallel processing, and the method can be considered as a competitor to existing computer arithmetic.

The alignment of a nematic liquid crystal (LC) parallel to the polarization direction of the laser could be induced by three types of polyimide (PI) films, a PI based on aromatic dianhydride and two PIs on alicyclic dianhydride, exposed to polarized pulsed laser at 266 nm at high fluence in air. The UV-visible absorption spectra of the PI films showed that a remarkable chemical change occurred after exposure at the high fluence in air. In contrast, in argon atmosphere the PI based on aromatic dianhydride was radiation-resistant and the exposed PI film could induce alignment of the LC molecules parallel to laser polarization. We estimate that the mechanism of the parallel alignment observed in argon is not the photodegradation but the orientation of the PI molecules.

By using full-color light emitting diode (LED) panel, we have been studying a stereoscopic full-color large television in broad daylight. In order to implement stereoscopic large display for the general public, optimum parameters of display elements and parallax barrier and viewing areas of stereoscopic display using parallax barrier are discussed. Although stereoscopic display with parallax barrier permits the viewer to view stereoscopic images without any special glasses, its viewing area is restricted by crosstalk and disappearing of pixels. Enlarged viewing areas, which are derived from the small ratio of light emitting region to pixel and a proper aperture ratio of parallax barrier, are analyzed. A model of a viewer standing toward the display is proposed because the viewer apart from the horizontal center of the display turns to the center point of LED display and this turning causes a deviation of viewer's eye position. Then, the allowable number of viewing locations is derived on "no crosstalk" and "no disappearance" conditions. The optimum aperture ratio of parallax barrier and the width of light emitting region is obtained through the optimization. The viewing area obtained from the analysis is confirmed by experiments using full-color LED panel. Relations between viewing area and the moire fringes is also discussed. The depth of the viewing area agrees the viewing distance where no moire fringe appears. Furthermore, possibility of display for the crowds is discussed.

In this paper we study general complex eigenvalue problems in engineering fields. The eigenvalue problems can be transformed into the associated problems for solving large systems of nonlinear ordinary differential equations (dynamic equations) by optimization techniques. The known waveform relaxation method in circuit simulation can then be successfully applied to compute the resulting dynamic equations. The approach reported here, which is implemented on a message passing multi-processor system, can determine all eigenvalues and their eigenvectors for general complex matrices without any restriction on the matrices. The numerical results are provided to confirm the theoretical analysis.

Natural language interface systems can accept more unrestricted queries from users than other systems, however it is impossible to understand erroneous sentences which include the syntax errors, unknown words and misspelling. In order to realize the superior natural language interface, the automatic error correction for erroneous sentences is one of problems to be solved. The method to apply the LR parsing strategies is one of the famous approaches as the robust error recovery scheme. This method is able to obtain a high correction accuracy, however it takes a great deal of time to parse the sentence, such that it becomes a very important task to improve the time-cost. In this paper, we propose the method to improve the time efficiency, keeping the correction accuracy of the traditional method. This method makes use of a new parsing table that denotes the states to be transited after accepting each symbol. By using this table, the symbol which is allocated just after the error position can be utilized for selecting correction symbols, as a result, the number of candidates produced on the correction process is reduced, and fast system can be realized. The experiment results, using 1,050 sentences including error characters, show that this method can correct error points 69 times faster than the traditional method, also keep the same correction accuracy as the traditional method.

An airborne cloud profiling radar (SPIDER) which has several unique features has been developed at CRL. In this paper, the objectives and design considerations are outlined, and the system is described. The features of SPIDER are summarized below. (1) A W-band frequency (95 GHz) is used to provide very high sensitivity to small cloud particles. (2) The radar is carried by a jet aircraft that can fly high above most clouds. (3) Full-polarimetric and Doppler capabilities are incorporated in the unit. (4) Almost all radar operational parameters are under software control, and most processing is in real time. (5) The design gives consideration to the study of cloud radiation and microphysics. The system has been completed and is still undergoing performance testing. The functions and performance of the SPIDER system are currently fulfilling the intentions of its design. Several interesting cloud features that had not been seen with previous instruments have already been observed.

Aiming at lower cost and further miniaturization, we developed a new optical coupling system for use as an optical interface of a parallel optical interconnect module, called ParaBIT-1. It consists of a new-structure 24-fiber bare fiber (BF) connector whose main parts are made of molded plastic and a 24-channel optical coupling component using new polymeric optical waveguide film. To prevent bare fibers from breaking, the BF connector plug has a fiber protector. This BF connector can be joined by direct physical contact between bare fibers in fiber guide holes with a 250-µm pitch. The buckling forces of the fibers themselves secure the physical contacts. The average measured insertion loss of the 24-fiber BF connector was 0.05 dB, and the return losses were over 35 dB. The optical coupling components are composed of a 24-ch polymeric optical waveguide film with 45 mirrors and the 24-fiber BF connector interface, and can be assembled by passive alignment. The high thermal stability of the film allows soldering, and the film is fabricated by direct photo patterning. The average insertion losses of the components for transmitter and receiver modules were 1.28 and 1.35 dB, respectively.

In this paper, as a practical application, we focus on the genetic algorithm (GA) for multi-head surface mounting machines which are used to populate printed circuit boards (PCBs). Although there have been numerous studies on the surface mounting machine, studies on the multi-head case are rare because of its complexity. The multi-head surface mounting machine can pick multiple components simultaneously in one pickup operation and this operation can reduce much portion of the assembly time. Hence we try to minimize the assembly time by maximizing the number of simultaneous pickups, resulting in reduction of PCB production cost. This research introduces a partial-link GA method for the single-head case. Then, we apply this method to the multi-head case by regarding a reel-group as one reel and a component-cluster as one component. The results of computer simulation show that our genetic algorithm is greatly superior to the heuristic algorithm that is currently used in industry.

In this paper, the improvement technique for a nonlinear parallel interference cancellation (PIC) receiver for a DS-CDMA system is studied, which cancels only the estimated multiple access interference (MAI) from specific users at each receiver stage. This technique was introduced as a PIC receiver using null zone hard decision in the proceeding of IEEE MILCOM '94, but the numerical results has not been fully provided with varying decision threshold. In this paper, the performance of the PIC receiver using null zone hard decision is shown in a Rayleigh fading channel. Also, a new PIC receiver with an adaptive decision threshold is proposed. In the proposed new PIC receiver, the decision threshold for partial cancellation is adjusted according to the statistic of its matched filter (MF) outputs. The BER of the proposed PIC receiver is obtained by simulation and compared with those of the conventional PIC receiver and the PIC receiver using null zone hard decision in a Rayleigh fading channel. It is shown that the proposed PIC receiver achieves better performance than the conventional PIC receiver and the PIC receiver using null zone hard decision in a Rayleigh fading channel.

Co-ferrite thin films have been fabricated on Corning glass substrates by a chelating sol-gel process. Structural and magnetic properties of the films have been studied as a function of annealing temperature using an X-ray diffraction (XRD) and a vibrating sample magnetometer. XRD results revealed that most of the Co-ferrite grains were randomly oriented. Rapid annealing (RA) and standard annealing (SA) processes were used for the variation of heat treatment and the characteristic comparison. Coercivity was changed with the thermal condition and the magnetization increased with the soaking time. With prolonged soaking time, however, the coercivity decreased due to the diffusion of cations from the glass substrate. RA in the preparation of Co-ferrite thin films was effective for preventing interdiffusion at interfaces and for forming a single phase in the case of reduced soaking time. A yttria stabilized zirconia (YSZ) buffer layer between the Co-ferrite layer and the substrate was effective for improving the magnetic properties of the films at higher temperatures. It was observed that Co-ferrite thin films were composed of grains typically 35 nm in size and their rms roughness was approximately 1.3 nm. The saturation magnetization of the thin films by subjected to rapid annealing at 900C for 150 seconds was 400 emu/cm3 and the coercivity of the films was approximately 3000 Oe.

This paper presents the implementation of a 3 V low power multi-rate of 156, 622, and 1244 Mbps clock and data recovery circuit (CDR) for optical communications tranceiver using new parallel clock recovery architecture based on dual charge-pump PLL. Designed circuit recovers eight-phase clock signals which are one-eighth frequency of the input signal. While the typical system uses the method that compares the input data with recovered clock, the proposed circuit compares a 1/2-bit delayed input data with the serial data generated by the recovered eight-phase clock signals. The advantage of the circuit is that the implementation is easy, since each sub blocks have one-eighth frequency of the input data signal. Morevover, since the circuit works at one-eighth frequency of the input data, it dissipates less power than conventional CMOS recovery circuit. Simulation results show that this recovery circuit can work with power dissipation of less than 40 mW with a single 3 V supply. All the simulations are based on HYUNDAI 0.65 µm N-Well CMOS double-poly double-metal technology.

In this paper, we propose an effective SOI yield engineering methodology by practical usage of 2D simulations. Process design for systematic yield of Fully-Depleted SOI MOSFET requires specific consideration of floating-body effects and parasitic channel leakage currents. The influence of varied SOI layer thickness to such phenomena is also complicated and substantial. Instead of time-consuming 3D simulators, 2D simulators are used to optimize the process considering these effects in acceptable turn around time. Our methodology is more effective in future scaled-down process with decreased SOI layer thickness.

Learning process is essential for good performance when a neural network is applied to a practical application. The backpropagation algorithm is a well-known learning method widely used in most neural networks. However, since the backpropagation algorithm is time-consuming, much research have been done to speed up the process. The block backpropagation algorithm, which seems to be more efficient than the backpropagation, is recently proposed by Coetzee in [2]. In this paper, we propose an efficient parallel algorithm for the block backpropagation method and its performance model in mesh-connected parallel computer systems. The proposed algorithm adopts master-slave model for weight broadcasting and data parallelism for computation of weights. In order to validate our performance model, a neural network is implemented for printed character recognition application in the TiME which is a prototype parallel machine consisting of 32 transputers connected in mesh topology. It is shown that speedup by our performance model is very close to that by experiments.