This paper proposes a new design method of nonlinear filtering and fixed-point smoothing algorithms in discrete-time stochastic systems. The observed value consists of nonlinearly modulated signal and additive white Gaussian observation noise. The filtering and fixed-point smoothing algorithms are designed based on the same idea as the extended Kalman filter derived based on the recursive least-squares Kalman filter in linear discrete-time stochastic systems. The proposed filter and fixed-point smoother necessitate the information of the autocovariance function of the signal, the variance of the observation noise, the nonlinear observation function and its differentiated one with respect to the signal. The estimation accuracy of the proposed extended filter is compared with the extended maximum a posteriori (MAP) filter theoretically. Also, the current estimators are compared in estimation accuracy with the extended MAP estimators, the extended Kalman estimators and the Kalman neuro computing method numerically.

In this paper, we consider the Integrate-and-Fire Model (ab. IFM) with two periodic inputs. The IFM outputs a pulse-train which is governed by a one dimensional return map. Using the return map, the relationship between the inputs and the output is clarified: the first input determines the global shape of the return map and the IFM outputs various periodic and chaotic pulse-trains; the second input quantizes the state of the return map and the IFM outputs various periodic pulse-trains. Using a computer aided analysis method, the quantized return map can be analyzed rigorously. Also, some typical phenomena are confirmed in the laboratory.

This paper investigates a new class of pulse compression codes in which the phase rotates clockwise, and afterward, rotates anticlockwise (or rotates anticlockwise, and afterward, rotates clockwise). The spectrum energy then concentrates to the narrower band compared to the conventional code such as the Barker code and the pulse is compressed not to the width of a single subpulses, but to the width made by a collection of several subpulses. It is revealed that, using the new code, PSL (Peak Sidelobe Level) can be reduced to -25.6 dB (1/19) -25.1 dB (1/18), which is much smaller than using the Barker code and Frank code, when the compression ratio is about 10 or larger. Furthermore, the signal-to-noise ratio after compression, the appropriate IF bandwidth and Doppler tolerance for the new code are estimated by simulation.

A very low spurious frequency doubler for wireless communication systems is proposed. The key to this technique is to change the input signal into a rectangular wave, which effectively suppresses the fundamental frequency and the odd harmonic components. The desired to undesired signal ratio (D/U) is better than 50 dBc at the desired output frequency of 1.1 GHz. The proposed doubler eliminates the need for the band-pass filters which occupy a large part of the radio frequency (RF) module. High order multipliers easily are fabricated with this method. In this paper, a quadrupler is also described.

We propose using punctured convolutional code for a Discrete Multitone (DMT) Asymmetric Digital Subscriber Line (ADSL) system to improve the data rate performance of ADSL. The theoretical performance of the systems with single coding rate for all subchannels, and with adaptive coding rate for each subchannel are presented respectively. It is found that the data rate performance of the proposed system is higher than the uncoded system.

In a multisystem data sharing environment (MDSE), the computing nodes are locally coupled via a high-speed network and share a common database at the disk level. To reduce the amount of expensive and slow disk I/O, each node caches database pages in its main memory buffer. This paper focuses on the MDSE that uses record-level locking as a concurrency control. While the record-level locking can guarantee higher concurrency than page-level locking, it may result in heavy message traffic. In this paper, we first propose a cache coherency scheme that can reduce the message traffic in the standard locking. Then the scheme is extended to the context where lock caching and lock de-escalation are adopted. Using a distributed database simulation model, we evaluate the performance of the proposed schemes under a wide variety of database workloads.

We have developed a practical 3-D integrated process simulator (3-D MIPS) based on the orthogonal grid. 3-D MIPS has a 3-D topography simulator (3-D MULSS) and 3-D impurity simulator which simulates the processes of ion implantation, impurity diffusion and oxidation. In particular, its diffusion and segregation model is new and practical. It assumes the continuity of impurity concentration at the material boundary in order to coordinate with the topography simulator (3-D MULSS) with cells in which two or more kinds of materials exist. And then, we introduced a time-step control method using the Dufort-Frankel method of diffusion analysis for stable calculation, and a selective oxidation model to apply to more general structures than LOCOS structure. After that, the 3-D MIPS diffusion model is evaluated compared with experimental data. Finally, the 3-D MIPS is applied to 3-D simulations of the nMOS Tr. structure with LOCOS isolation, wiring interconnect and pn-junction capacitances, and DRAM storage node area.

A distributed computing system consists of processing elements, communication links, memory units, data files, and programs. These resources are interconnected via a communication network and controlled by a distributed operating system. The distributed program reliability (DPR) in a distributed computing system is the probability that a program which runs on multiple processing elements and needs to retrieve data files from other processing elements will be executed successfully. This reliability varies according to 1) the topology of the distributed computing system, 2) the reliability of the communication edges, 3) the data files and programs distribution among processing elements, and 4) the data files required to execute a program. In this paper, we show that computing the distributed program reliability on a star distributed computing system is #P-complete. A polynomially solvable case is developed for computing the distributed program reliability when some additional file distribution is restricted on the star topology. We also propose a polynomial time algorithm for computing the distributed program reliability with approximate solutions when the star topology has no the additional file distribution.

In this paper, we propose methods for testing the usability of graphical user interface (GUI) applications based on log files of user interactions. Log analysis by existing methods is not efficient because evaluators analyze a single log file or log files of the same user and then manually compare results. The methods proposed here solve this problem; the methods enable evaluators to analyze the log files of multiple users together by detecting interaction patterns that commonly appear in the log files. To achieve the methods, we first clarify usability attributes that can be evaluated by a log-based usability testing method and user interaction patterns that have to be detected for the evaluation. Based on an investigation on the information that can be obtained from the log files, we extract the attributes of clarity, safety, simplicity, and continuity. For the evaluations of clarity and safety, the interaction patterns that have to be detected include those from user errors. We then propose our methods for detecting interaction patterns from the log files of multiple users. Patterns that commonly appear in the log files are detected by utilizing a repeating pattern detection algorithm. By regarding an operation sequence recorded in a log file as a string and concatenating strings, common patterns are able to be detected as repeating patterns in the concatenated string. We next describe the implementation of the methods in a computer tool for log-based usability testing. The tool, GUITESTER, records user-application interactions into log files, generates usability analysis data from the log files by applying the proposed methods, and visualizes the generated usability analysis data. To show the effectiveness of GUITESTER in finding usability problems, we report an example of a usability test. In this test, evaluators could find 14 problems in a tested GUI application. We finally discuss the ability of the proposed methods in terms of its log analysis efficiency, by comparing the analysis/sequence time (AT/ST) ratio of GUITESTER with those of other methods and tools. The ratio of GUITESTER is found to be smaller. This indicates the methods make log analysis more efficient.

In this paper, we investigate the bit error rate (BER) performance of Direct Sequence-Code Division Multiple Access (DS-CDMA) systems under impulsive radio noise environments, and propose a novel DS-CDMA receiver which is designed to be robust against impulsive noise. At first, employing the Middleton's Class-A impulsive noise model as a typical model of impulsive radio noise, we discuss the statistical characteristics of impulsive radio noise and demonstrate that the quadrature components of impulsive noise are statistically dependent. Next, based on the computer simulation, we evaluate the BER performance of a conventional DS-CDMA system under a Class-A impulsive noise environment, and illustrate that the performance of the conventional DS-CDMA system is drastically degraded by the effects of the impulsive noise. To deal with this problem, motivated by the statistical dependence between the quadrature components of impulsive radio noise, we propose a new DS-CDMA receiver which can eliminate the effects of the channel impulsive noise. The numerical result shows that the performance of the DS-CDMA system under the impulsive noise environment is significantly improved by using this proposed receiver. Finally, to confirm the effectiveness of this proposed receiver against actual impulsive radio noise, we evaluate the BER performance of the DS-CDMA system employing the proposed receiver under a microwave oven (MWO) noise environment and discuss the robustness of the proposed receiver against MWO noise.

A device simulator that simulates device performance in the cyclic bias steady state was developed, and it was applied to GaAs hetero-junction FET (HJFET) pulse pattern effect. Although there is a large time-constant difference between the pulse signals and deep trap reactions, the simulator searches the cyclic bias steady states at about 30 iterations. A non-linear shift in the drain current level with the mark ratio was confirmed, which has been estimated from the rate equation of electron capture and emission based on Shockley-Read-Hall statistics for deep traps.

Equipment simulation can provide valuable support in reactor design and process optimization. This article describes the physical and chemical models used in this technique and the current state of the art of the available software tools is reviewed. Moreover, the potential of equipment simulation will be highlighted by means of three recent examples from advanced quarter micron silicon process development. These include a vertical batch reactor for LPCVD of arsenic doped silicon oxide, a multi station tungsten CVD reactor, and a plasma reactor for silicon etching.

This paper presents a method of calculating an interval including a bifurcation point. Turning points, simple bifurcation points, symmetry breaking bifurcation points and hysteresis points are calculated with guaranteed accuracy by the extended systems for them and by the Krawczyk-based interval validation method. Taking several examples, the results of validation are also presented.

A new concept of "an imperfect singular solution" is defined as an approximate solution which becomes a singular solution by adding a suitable small perturbation to the original equations. A numerical method is presented for proving the existence of imperfect singular solutions of nonlinear equations with guaranteed accuracy. A few numerical examples are also presented for illustration.

An on-chip high voltage generator applicable to low voltage flash memory is introduced. Bootstrapped gate transfer switches of two parallel paths suppress the voltage loss due to threshold voltage drop of transfer transistors. The simulated results demonstrate that proposed circuit designed with NMOS transistors having 0.8 volt threshold voltage works like an ideal charge pump circuit near 1.0 volt range with enough current driving capability.

This paper reports computational results of a new approach of analyzing network reliability against probabilistic link failures. This problem is hard to solve exactly when it is large-scale, which is shown from complexity theory, but the approach enables us to analyze networks of moderate size, as demonstrated by our experimental results. Furthermore, this approach yields a polynomial-time algorithm for complete graphs, whose reliability provides a natural upper bound for simple networks, and also leads to an efficient algorithm for computing the dominant part of the reliability function when the failure probability is sufficiently small. Computational results for these cases are also reported. This approach thus establishes a fundamental technology of analyzing network reliability in practice.

We show that the permanent of an m n rectangular matrix can be computed with O(n 2m 3m) multiplications and additions. Asymptotically, this is better than straightforward extensions of the best known algorithms for the permanent of a square matrix when m/n log3 2 and n .

We propose and describe a new configuration for splitting and combining operations of high-speed amplitude-modulated optical signals between the two interacting beams by using two-wave mixing in photorefractive Cu-doped (K0.5 Na0.5)0.2 (Sr0.61 Ba0.39)0.9 Nb2O6 (Cu-KNSBN) crystal. These operations are simultaneously achieved by changing the intensity ratio of the two incident beams. We also apply this scheme to a photorefractive pulse shaping in the time domain that consists of two amplitude-modulated beams that are coupled automatically through two-beam interactions in the crystal. Some preliminary experimental results are presented and discussed.

In this paper there suggested is a bifurcated (or multiple) input-queued ATM switch in which a buffer for each input port is divided into multiple (m) buffer blocks, i. e. , bifurcated buffers, for enhancement of the limited throughput of the ordinary input-queued switch using a single FIFO. As the contention/arbitration rule for the bifurcated input-queued switching scheme, free and restricted contention rules are come up with and discussed. The free rule allows an input port to switch up to m cells at the cost of internal speedup. With the restricted rule, on the other hand, an input port can switch no more than one cell in a time slot so that the switch operates at the same speed as the external link speed. The throughput bound for the bifurcated input-queued switch is analyzed for both rules through the generalization of the analysis by Karol et al. The throughput bound approaches to 1.0 as m becomes large enough, irrespective of the contention/arbitration rule.

This paper considers methods to design multiple-output networks based on decision diagrams (DDs). TDM (time-division multiplexing) systems transmit several signals on a single line. These methods reduce: 1) hardware; 2) logic levels; and 3) pins. In the TDM realizations, we consider three types of DDs: shared binary decision digrams (SBDDs), shared multiple-valued decision diagrams (SMDDs), and shared multi-terminal multiple-valued decision diagrams (SMTMDDs). In the network, each non-terminal node of a DD is realized by a multiplexer (MUX). We propose heuristic algorithms to derive SMTMDDs from SBDDs. We compare the number of non-terminal nodes in SBDDs, SMDDs, and SMTMDDs. For nrm n, log n, and for many other benchmark functions, SMTMDD-based realizations are more economical than other ones, where nrm n is a (2n)-input (n1)-output function computing (X2+Y2)+0.5, log n is an n-input n-output function computing (2n1)log(x1)/nlog2, and a denotes the largest integer not greater than a.