bluuebunny/crossref_metadata_2025 huggingface dataset:
A shared‐memory virtual channel queue for ATM broadband terminal adaptors
Authors: Chao H. Jonathan , Smith Donald E.
Published: July 2007

In order to take advantage of the low entry cost of the future public ATM (asynchronous transfer mode) network with shared facilities, it is highly desirable to interconnect different hosts and local area networks (LANs) to the ATM network. The interface between the computer hosts or LANs and the ATM network, commonly called a broadband terminal adaptor (BTA), provides the necessary format conversion for the data packets and the ATM cells. It is conceivable that multiple packets from different virtual channels are interleaved as they arrive at the receive‐end BTA. The BTA must have a sufficiently large buffer, called a virtual channel queue (VCQ), to temporarily store the partially received packets. Once a complete packet has been received, it is forwarded to the host or LAN. Whenever the buffer fills with all incomplete packets, a packet must be discarded to make room for others. In this paper, we first study, through computer simulations, the buffer size requirement of a shared‐memory VCQ for different numbers of virtual channels at various packet loss probabilities. We then present two different implementation architectures for the shared‐memory VCQ, and compare their hardware complexity. The second architecture with linked‐queue approach, adopted in our work, requires less buffer and has better scalability to accommodate a large number of virtual channels. Various possible error conditions, such as cell losses in the ATM network and the VCQ buffer overflow, are considered. Corresponding solutions are proposed and included in the VCQ designs.
A hybrid approach to the transmission of telephony over a passive optical network
Authors: Mudhar Richard
Published: July 2007

Passive optical networks (PONs) are attractive for the provision of telephony via optical fibre in the local loop, and have generally tended to concentrate on the use of time‐division multiple access for transmission. This paper describes a hybrid transmission method using sub‐carrier multiplexing (SCM) and time division multiplexing (TDM) which seeks to reduce the overall complexity of the system, thereby lowering costs.
Bandwidth allocation and selective discarding for variable bit rate video and bursty data calls in ATM networks
Authors: Decina Maurizio , Toniatti Tiziana
Published: July 2007

Congestion control mechanisms are required in ATM networks to fairly and efficiently allocate network resources to the various service types. Bandwidth allocation is a preventive control mechanism. On the basis of the traffic description given by the source, of the traffic load along the connection route and of the cell performance requirements, this mechanism gives a criterion to accept or reject a virtual connection request. A bandwidth called ‘equivalent bandwidth’ is allocated in order to ensure the cell transport objectives.

This paper proposes a definition of equivalent bandwidth for stream, bursty data and variable bit rate video (VBRV) sources. The equivalent bandwidth values are evaluated by simulation considering both homogeneous and heterogeneous sources. In the heterogeneous mixes with different cell loss probability requirements the selective discarding mechanism permits a more efficient utilization of the network resources.
Performance of M‐QAM modulations for indoor radio communications with combined diversity and equalization techniques
Authors: Casadevall Fernando J. , Valdovinos Antonio
Published: July 2007

Digital indoor radio communications systems have become an attractive proposal as they could provide the user high quality voice and low rate data services with total mobility. However, indoor communications are affected by multipath propagation that restricts their application imposing an upper limit on the system data rate. To overcome this drawback diversity and channel equalization could be considered. In this paper the performances of 4, 16 and 64‐QAM modulations in a radio communications indoor environment are presented. The results show that a system without protection has very limited performance. Diversity techniques are efficient when the radio channel can be assumed to be non‐selective. For systems operating in selective fading channels joint equalization and diversity techniques are necessary to fight the degrading effect introduced by the channel. Moreover, if correlation between the two diversity channels is taken into account, the system performances remain almost unchanged, assuming that the correlation coefficient between the two diversity branches is lower than 0.6 to 0.7 approximately.
A codec for HDTV signal transmission through terrestrial and satellite digital links
Authors: Cominetti Mario , Molo Francesco
Published: July 2007

A codec for digital transmission of HDTV is described. The bit‐rate compression algorithm is based on advanced techniques such as spatial discrete cosine transform (DCT), temporal differential PCM (DPCM), variable length coding. The codec is designed to operate with both the interlaced studio systems 1125/60 and 1250/50, and, thanks to the inherent flexibility of the packet structure, a wide range of line bit‐rates can be used as a compromise between video quality and bit‐rate constraints of the digital transmission link. The flexibility of the HDTV codec is highlightened through examples of applications over satellite digital links in practical situations.
HDMAC encoder—first generation: Experience and applications
Authors: Bathe Paul
Published: July 2007

This article deals with the first generation of HDMAC ENCODER equipment. Methods for bandwidth reduction, processing to obtain a compatible picture and the test concept for the encoder will be presented. In addition, the 140‐Mbit/s transmission system for HDMAC will be described and future methods for transmission and application of HDMAC illustrated.
Performance evaluation of error recovery schemes in high‐speed networks
Authors: Nilsson Arne A. , Lai Fuyung
Published: July 2007

Error control in high speed communication networks is usually applied either as a link‐by‐link scheme or an end‐to‐end scheme. The performance of such schemes is analyzed in this paper. The impact of errors due to transmission errors as well as dropped packets due to buffer overflow is incorporated in the models.
Design of a non‐blocking shared‐memory copy network for ATM
Authors: Bianchini Ronald P. , Kim Hyong S.
Published: July 2007

The design of a copy network is presented for use in an ATM (asynchronous transfer mode) switch supporting BISDN (broadband integrated services digital network) traffic. Inherent traffic characteristics of BISDN services require ATM switches to handle bursty traffic with multicast connections. In typical ATM switch designs a copy network is used to replicate multicast cells before being forwarded to a point‐to‐point routeing network. In such designs, a single multicast cell enters the switch and is replicated once for each multicast connection. Each copy is forwarded to the routeing network with a unique destination address and is routed to the appropriate output port. Non‐blocking copy networks permit multiple cells to be multicasted at once, up to the number of outputs of the copy network. Another critical feature of ATM switch design is the location of buffers for the temporary storage of transmitted cells. Buffering is required when multiple cells require a common switch resource for transmission. Typically, one cell is granted the resource and is transmitted while the remaining cells are buffered. Current switch designs associate discrete buffers with individual switch resources. Discrete buffering is not efficient for bursty traffic as traffic bursts can overflow individual switch buffers and result in dropped cells, while other buffers are under‐used. A new non‐blocking copy network is presented in this paper with a shared‐memory input buffer. Blocked cells from any switch input are stored in a single shared input buffer. The copy network consists of three banyan networks and shared‐memory queues. The design is scalable for large numbers of inputs due to low hardware complexity, O (Nlog2N), and distributed operation and control. It is shown in a simulation study that a switch incorporating the shared‐memory copy network has increased throughput and lower buffer requirements to maintain low packet loss probability when compared to a switch with a discrete buffer copy network.
Novel algorithm for time division multiple access in broadband ISDN passive optical networks
Authors: Glade M. , Keller H.
Published: July 2007

For shared access to a broadband communication network using the asynchronous transfer mode (ATM) a passive optical network (PON) has previously been proposed. A novel algorithm to evaluate the time division multiple access (TDMA) protocol which controls the traffic from the various subscribers towards the shared access equipment (upstream direction) is proposed. It uses counters to estimate the moment of a data packet arrival at the subscriber side. By this ‘look‐ahead’ technique no extra upstream channels are needed to initiate the polling by the subscriber. The algorithm guarantees fair access for all subscribers and minimizes the necessary overhead. Both the maximum access delay and overhead may be readily calculated, and the obtained results were supported by numerical simulation. Applicability in the standard broadband network environment has been proved by hardware design simulation.
On the combined effect of DPSK modulation level and block coding on cellular capacity
Authors: Gejji Raghvendra R.
Published: July 2007

In this paper we consider how closely the theoretical limiting cellular capacity, given recently as a function of CIR (carier‐to‐interference ratio) by Gejji, may be achieved by commonly used modulation and coding schemes such as DPSK and BCH coding. Specifically, we consider the variation in channels/cell with CIR in the face of varying modulation level and block coding length. We also compare performance with the limit given recently. It is seen that the advantage of QPSK over 8PSK is reduced in the presence of coding compared to without coding. It is also seen that the ratio of actual capacity to the limiting value is constant over a range of CIR values.
Efficient algorithms for multiple destinations routeing
Authors: Leung Yiu‐Wing , Yum Tak‐Shing
Published: July 2007

A number of important problems in computers and telecommunications, such as distributed databases and multipoint multimedia conferencing, all require the solution of a generic problem called multiple destinations routeing (MDR). In this paper, we formulate the MDR problem as a zero‐one integer programming problem and propose a technique to reduce the computation required for the optimum solution. Three heuristics are designed for large MDR problems. Heuristic A can offer different degrees of optimality with different amounts of time allowed for the solution. Heuristic B is a modification of Prim's algorithm for the minimum spanning tree. It gives a fairly good solution with very little computation. Heuristic C is based on Heuristic B and is for minimizing the number of edges in the multicast tree (i.e. assuming that all edge weights are the same). It always gives a better solution than Heuristic B. Simulation on two example networks shows that Heuristics A and C always give better solutions (or lower cost connection paths) than the improved RS algorithm, which has up to now been the best heuristic.
Deterministic access protocols for packet radio networks
Authors: Paschos S. A. , Anagnostou M. E. , Afrati F. N.
Published: July 2007

In this paper, multiple‐phase deterministic protocols for packet radio networks are introduced and analysed. Two modes of information transfer are considered, namely (a) broadcasting and (b) point‐to‐point transmission. We explore systematic ways of designing multiple‐phase protocols and apply them on Manhattan networks. The proposed protocols are studied primarily from the point of view of throughput efficiency. Delay analysis is also presented.
ATM—success or failure? Economic remarks on the introduction of broadband technology in Europe
Authors: Anstötz Karin
Published: July 2007

The introduction of ATM and broadband‐based equipment into the European market requires considerable capital investment. It will result in a structural technological change, affecting the competitiveness of the European economy. Successful introduction depends on how both ATM network equipment and broadband based end‐user equipment are brought onto the market. This paper focuses on economic benefits and anticipating marketing strategies, applicable in Europe with its specific, historically evolved structures. The price to pay for this ‘in‐sight information’ is leaving out a global comparison. Refraining from evaluation whether conditions are good or bad for Europe or other areas, the article explains what conditions can be found there recently and where are the chances and challenges right now.
Burstiness and resource management in ATM networks
Authors: Boyer Jacqueline , Dupuis Alain , Guillemin Fabrice
Published: July 2007

Networks based upon the asynchronous transfer mode (ATM) provide for high flexibility to cope with a wide range of applications, some of them producing highly sporadic traffic. Therefore, the problem of burstiness has become in the last few years a key issue for such networks. A basic question is how to dimension network buffers in the presence of bursty traffic? In this paper we investigate the concept of burstiness and its impact on resource management. In burstiness characterization encountered in the literature, special attention has been given to the squared coefficient of variation of inter‐arrival time Cv2 in a cell arrival process. In order to observe the impact of bursty traffic on a queue, we develop in the present paper a ‘bursty’ traffic model, namely the two‐stage hyper‐Bernoulli cell arrival process, HBP2, for short. We numerically solve the HBP2/D/1/K queue. We especially derive the rejection probability Ploss. Numerical results are then thoroughly studied and we discuss the relevance for burstiness characterization of Cv2 and peak to mean rate ratio B. We draw attention to the concept of local overload, i.e. when the arrival rate is greater than the server rate. This seems to be the most relevant phenomenon in the impact of a bursty traffic on a queue. These results are finally applied to the problem of resource management in ATM networks.
The zebrafish vitronectin receptor: Characterization of integrin αV and β3 expression patterns in early vertebrate development
Authors: Ablooglu Ararat J. , Kang Jian , Handin Robert I. , Traver David , Shattil Sanford J.
Published: July 2007

αVβ3 is a receptor for vitronectin and other extracellular matrix ligands, and it has been implicated in angiogenesis and osteoclast function in mammals. We have cloned full‐length cDNAs of zebrafish integrin αV (itgαV), and two paralogous zebrafish β3 integrins (itgβ3.1 and itgβ3.2). Whole‐mount in situ hybridization analysis revealed that αV and β3.1 share overlapping expression domains in apical ectodermal ridge, ventricular myocardium, hypothalamus, posterior tuberculum, medial tectal proliferation zone, and in the odontogenic field of the bilateral pharyngeal dentitions. In contrast to β3.1, β3.2 is transiently expressed throughout the developing embryo. In situ hybridization profiles and heterologous expression of proteins in tissue culture cells suggest that β3.1 is the major β3 paralog that associates with αV in zebrafish. Furthermore, when β3.1 expression profiles are compared to those of other potential αV partners (β1, β5, and β8), pharyngeal dentitions appear to represent a unique expression field for αV and β3.1. Developmental Dynamics 236:2268–2276, 2007. © 2007 Wiley‐Liss, Inc.
Testable design for cell‐based design ASICs and its application to VLSI image signal processor
Authors: Kawai Hiroyuki , Nakagawa Shin‐Ichi , Yoshimoto Masahiko , Horiba Yasutaka , Ogihara Takuji , Tada Akiharu
Published: July 2007

This paper proposes a testing method which provides an efficient test for the library macrocell built in a large‐scale and high‐speed application‐specific IC (ASIC) of a cell‐based design, especially in the parallel processor for the image processing VLSI. The proposed method consists of the test pattern assembly tool and the testability design for the efficient test. The test pattern is assembled automatically from the test pattern library of the macrocell and the access sequence description, which describes the access procedure from the external pins of the LSI and/or scan registers to the input/output pins of the macrocell built in the LSI.

By the foregoing description, the access to the macrocell through the sequential circuit also is possible. With regard to the design for testability, the clock control method, the bus driver circuit, and the test mode control method are newly devised and are combined with the system bus and the scan register.

The proposed method is applied to the high‐speed image processing VLSI. The test patterns for four library macrocells in the LSI (two RAMs, multiplier, and PLA) were assembled in one day. The proposed method can also be applied to the user developed macrocell which is utilized iteratively in an LSI. The increase of the number of transistors and the transistor area is suppressed to 3.1 percent (in regard to logic unit) and 0.6 percent (in regard to the whole chip area), respectively. It is verified that there is little decrease of the operational speed in the system operation and does not affect the high‐speed image processing.
Spectral peak enhancement methods for 1‐D and 2‐D signals and their applications
Authors: Shimamura Tetsuya , Suzuki Jouji
Published: July 2007

In this paper, we propose a method to enhance the maximum spectral peaks of signal components corrupted by noise for one‐ and two‐dimensional (1‐D and 2‐D) signals under the condition that no a priori information is given. This method does not use a conventional filter where the passband is one and the stopband is zero but uses a filter where the spectral characteristics of the signal to be extracted from the input signal are the desired characteristics; that is, the filter is dependent on the input signal. For 1‐D signals, we demonstrate that the signal components can be satisfactorily enhanced by iterative processing using the fast Fourier transform (FFT) given an “autoregressive (AR signal + white noise signal” and a “harmonic signal + white noise signal.” For 2‐D signals, the amount of computation is decreased significantly and good spectral enhancement is possible compared to conventional methods. Furthermore, the possible application of this method to the design of narrowband plane wave detection filters, which are difficult to design using conventional methods, is presented.
A parallel processing method for implementing the RSA cryptosystem
Authors: Iwamura Keiichi , Matsumoto Tsutomu , Imai Hideki
Published: July 2007

Modular multiplication: R = A · B mod N (where A, B, N, and R are integers) is an essential operation used in public‐key cryptosystems such as RSA, El Gamal, and Rabin. Thus, if high‐speed modular multiplication circuits can be constructed, these cryptosystems can operate at high speeds. In this paper, we show how to construct, with a high‐speed modular multiplication circuit which employs parallel processing methods using systolic arrays, a circuit which performs modular exponentiation by repeated modular multiplication. In particular, we demonstrate its validity by using the RSA scheme as a first concrete example. Since a circuit using the method of this paper as its construction rule has simple and regular structure, it provides an optimal construction of a highspeed RSA chip in VLSI. The method is also applicable for a simple implementation of the RSA scheme with small‐sized chips. In this case, the number of chips needed by this method (the circuit size) allows the practical realization of proportionately higher speeds. Flexibility can be achieved for a change in the number of key bits by a corresponding increase or decrease in the number of chips.
An approximation method of group delay characteristics of 1‐D and 2‐D discrete time systems
Authors: Ino Kazuhiro , Sakai Masayoshi , Hamada Nozomu
Published: July 2007

In the fields of signal transmission and its processing, compensation of phase or group delay distortion is an important problem.

This paper proposes an approximation method of group delay characteristic of one‐dimensional (1‐D) and 2‐D discrete‐time systems using an extended equation error function as its performance index. Since the phase approximation problem is inherently nonlinear, some iterative approaches have been proposed. Its disadvantage is in the increase of the amount of computation.

Another method to transform group delay approximation problem to power spectrum approximation problem is presented. This indirect approach leads to the minimum squared error problem which is easily solved but does not yield a satisfactory result.

In the first part of this paper, the 1‐D group delay approximation problem is formulated to a linear problem in group delay domain. Then we apply the quasi‐least mean squared method to it. In the latter part of this paper, the 1‐D method is extended to the 2‐D group delay approximation problem. Some examples are shown to verify the effectiveness of the method.
A stable algorithm for block adaptive filtering
Authors: Oishi Kunio , Fukumoto Masahiro , Kubota Hajime
Published: July 2007

Two methods have been proposed for calculating the block orthogonal projection algorithm using the Moore‐Penrose generalized inverse matrix. One is the conjugate gradient method, and the other is the block adaptive algorithm composed of the Gram‐Schmidt orthogonalization and the learning identification. Both computation methods are suited to the high‐speed estimation of the optimal coefficients with a small computational complexity. However, the operation may become very unstable due to the effects of observation error, quantization error, and other factors.

This paper proposes a method of realizing the block orthogonal projection algorithm with the learning identification, where the orthogonal basis of the space spun by the state matrix in the block adaptive filter is used as the direction of modification. A feature of this method is that the orthogonal basis is calculated using the orthogonal projection matrix. Computer simulation shows that the proposed adaptive algorithm realizes a very stable operation without being affected by either the quantization error, the operational error, or the observation noise.
A simple derivation of the riccati equation for H∞ control via state feedback
Authors: Shimizu Kiyotaka , Hanabusa Masataka , Tamura Taro
Published: July 2007

A derivation of the Riccati equation giving a necessary and sufficient condition for H∞ control by state feedback is presented. It is proved by solving the LQ‐max problem which is equivalent to the satisfaction condition (H∞ norm constraint condition) such that the uniform norm ∣Tvz∣ of a transfer operator T from the disturbance v to the controlled output z is kept below a prescribed γ.

Based on the state space representation, the proof is achieved by extending optimal regulator theory. While normal proofs are based fundamentally on the analysis of the H∞ norm in the frequency domain, it is performed fully in the time domain. This paper provides a direct and self‐contained proof.
Coupled‐mode theory of SAW periodic structures
Authors: Suzuki Yuji , Takeuchi Masao , Nakamura Kiyoshi , Hirota Kazuhiro
Published: July 2007

The coupled‐mode theory is extremely useful for analysis of such periodic structures as grating reflector, resonator, and unidirectional transducer making use of electrode reflection as important constituent elements for the SAW devices. Here, the coupled‐mode equations describing the transduction characteristics of the inter‐digital electrode transducer (IDT) are derived directly by the perturbation theory. In addition, the parameters for the coupled‐mode equations are presented for quartz, LiTaO3and LiNbO3substrates.

Next, based on the coupled‐mode equations, the relationship among the quantities of the electrical port and two acoustic ports of the IDT is derived. The entire periodic structure was represented by a simple distributed equivalent circuit. The equivalent circuit analysis method is described for the analysis of the device characteristics. To show the usefulness of the present method, a backward‐wave type trapped‐energy SAW resonator and the resonator coupled filter are analyzed.
Branch‐and‐bound placement for building block layout
Authors: Onodera Hidetoshi , Taniguchi Yo , Tamaru Keikichi
Published: July 2007

This paper proposes a placement technique based on the branch‐and‐bound method for the block placement problem in building block layout. In contrast to a traditional method of finding an approximate solution by a heuristic approach, the proposed method seeks a solution from all possible placements.

To find the solution efficiently, the branch‐and‐bound operation suited to the placement problem is devised. The proposed method positively considers the constraints imposed on routing length and placement configuration since they could be utilized for restricting the solution space. When the constraints are stronger, the solution space is more restricted, which helps to complete the search of the solution in a short time.

By an experimental investigation concerning the number of blocks that can be handled at a time, it is seen that almost six blocks can be handled if there is no constraint. When the number of blocks exceeds this limit, the circuit is decomposed in a hierarchical way and the branch‐and‐bound placement is applied to each subproblem until the layout of the whole circuit is determined. The proposed placement method is applied to the standard benchmark circuit for building block layout, and it is seen that the result by the proposed method is better than or very close to the best result reported so far.
A measure for selecting source signals used in quality assessment of coded music signals
Authors: Takahashi Akira , Nagabuchi Hiromi
Published: July 2007

In order to establish the quality assessment method for the wideband high‐quality acoustic telecommunication, the selection of the source signal is one of the important issues. The effect of the source signal used in the quality assessment on the subjective quality must be analyzed, and the measure for the selection of the source signals must be developed based on the result of analysis.

This paper considers the 20‐kHz band music signal and a measure for selecting the source signal is proposed to be used in the assessment of the coding distortion, which is one of the deteriorating factors for the communication quality. The effectiveness of the measure is demonstrated. As the first step, the “noisiness of the mid‐band signal,” the “flatness of spectrum envelop” and the “harmonicity of spectrum” are considered as the features that affect the subjective assessment score of the coded music signal. A measure for selecting the source signal based on those feature parameters is proposed and the parameters are optimized by the training data. The assessment experiment is conducted using the source signal recorded in the acoustic signal set (SQAM‐CD) recommended by CCIR, and the effectiveness of the proposed selection measure is verified when it is applied to the unknown data. It is also shown that the performance of the assessment object is more accurately evaluated using the proposed selection measure than in the case where the source signals are selected at random.
Fast stabilized adaptive algorithm for IIR bandpass/notch filters for a single sinusoid detection
Authors: Li Shang , Takahashi Nobuaki , Takebe Tsuyoshi
Published: July 2007

In this paper, a new algorithm for the detection of a single sinusoid corrupted by Gaussian noise using IIR adaptive bandpass/notch filter is presented. As the first step, the relation between the convergence speed and the filter Q‐factor in IIR adaptive bandpass filter is analyzed. Based on the result of analysis, an algorithm is derived in which the filter Q‐factor and the adaptive control signal generator Q‐factor are made continuously variable so that they are inversely proportional to the distance between the filter center frequency f0 and the frequency f of the sinusoid to be detected. This makes both the convergence speed of f0 and f and the resolution high. Then it is found that limiting the maximum amplitude response of the adaptive control signal generator to a value proportional to sin 2πf can suppress the coefficient fluctuation after convergence effectively. By this approach, an IIR adaptive filter with a high Q can easily be realized. As the next step, an additional high‐speed and highly stable adaptive algorithm is proposed in which the step size of the filter coefficient update is made to vary inversely with the filter Q‐factor. A realization of the IIR adaptive notch filter is also presented. Finally, the usefulness of the proposed adaptive algorithm is verified by a computer simulation.
Minimum steady‐state variance control
Authors: Kisaka Masashi
Published: July 2007

This paper discusses the design of the digital controller, which minimizes the steady‐state variance of the output when a known external disturbance is applied to a control system. The first‐order control object is considered as an example, and the cases of colored external noise and the sinusoidal disturbance are discussed. It is shown through discussions that the steady‐state variance of the output can be represented in the form of the Lyapunov equation. It is pointed out that if the controller coefficient is found to minimize the function, the steady‐state variance can be minimized.

Using the proposed method, the order of the controller can be determined independently of the order of the controlled object as long as the system can be stabilized. For the motor control system containing an analog band‐elimination filter, for example, it is possible to determine the coefficient of the digital PID controller to minimize the positioning error.
Analysis of weak nonlinear regulator problems with the solution confined to the integral manifold
Authors: Eguchi Masayoshi , Shidama Yasunari , Yamaura Hiroo , Cai Dawei
Published: July 2007

This paper uses the fixed‐point theorem to generate a set of sufficient conditions which confine the solutions of weak nonlinear differential equations to some low‐order stable integral manifold. Furthermore, it is shown that these conditions can be weakened to a great extent if the initial values of the differential equations are confined to a bounded region.

A method is proposed for finding the integral manifold in an analytic form such as a Fourier series and a new calculation algorithm which applies the Newton method and other techniques. Next, the obtained results are applied to weak nonlinear optimal regulator problems and sufficient conditions are derived for the existence of a nonlinear feedback control law which meets the necessary conditions for optimality. Simulations using the algorithm exhibited favorable results.
A method for solving reliability optimization problem with incomplete FDS by Fuzzy multiobjective 0–1 linear programming
Authors: Sasaki Masato , Gen Mitsuo
Published: July 2007

In general, inevitably the particular structure called generalized upper bounding (GUB) occurs when transforming the reliability optimization problem such as optimal unit selection and redundant allocation. These are formulated as the nonlinear integer programming problem and transformed to the 0‐1 linear programming problem.

Recently, a method for solving the fuzzy multi‐objective 0‐1 linear programming (0‐1 FMOLP) problem which extends the efficient method considering the GUB structure to the more general MOLP problem is proposed. Also, the method is extended to deal with the fuzziness of the goal value toward the objective function. However, this method is not considered for the break‐down of the fault‐detecting and switching (FDS) device; thus, it does not sufficiently cope with the real world's reliability optimization problem.

From these viewpoints, an algorithm is proposed for solving the optimal redundant unit selection problem that optimizes the system reliability with imperfect FDS device by fuzzy 0–1 MOLP. The method proposed here considers the fuzziness of the decisionmaker (DM) toward the goal value of each objective function by introducing the fuzzy goal. Further, this method enables the DM to determine the most satisfactory solution to the attainment of each goal value of the objective function and constraint and can cope with the realistic optimal design of the system reliability problems.
Protection against trojan horses by source code analysis
Authors: Saito Tadao , Aida Hitoshi , Kawaguchi Youji
Published: July 2007

The technology of security in computer networks has far‐reaching implications. In this paper, assuming a UNIX network system, which is the most popular currently, we enumerate the threats against security and classify the problems. Among the problems so defined, we consider particularly the Trojan horse problem, which is important when a program is received from the outside; and we propose a method of protection against Trojan horses. In the proposed protection method, objects which have been modified by the source program are extracted and are compared with a previously prepared list (the condition list) of objects which should not have been modified. In this method, verification of the security of the program needs to be done only at the time of its installation, so there is no loss in efficiency of performance at run time. Also, we can prevent security violations which cannot be regulated by controlling access and flow. In the proposed method, the major problem is determining the extent to which altered objects can be detected. In this regard, we perform soine experiments on the free software X11R4 and TeX. Finally, based on the results of the experiments, we evaluate the proposed protection method on the security of programs imported from the outside.
Chip compaction method with automatic jog insertion
Authors: Yamamoto Wataru , Awashima Toru , Sato Masao , Ohtsuki Tatsuo
Published: July 2007

The realization of an electronic circuit in the smallest possible area is the key to a successful LSI design. As a result, research on one‐dimensional compaction methods has been active on reducing the area of a given IC layout. Further, it is desirable to reduce the area with jogs in wiring patterns.

Compaction methods have been proposed that automatically add jogs effectively in the channel routing region for area reductions. These methods include the plane‐sweep method developed in computational geometry and are fast and flexible enough to adapt to complex design rules. However, it is not only very difficult but inefficient to apply these methods to the entire chip area including functional blocks.

This paper proposes a chip compaction method which inserts jogs while maintaining the advantages of the compaction methods based on the plane‐sweep method. The proposed method is based on the shortest path search under a constraint graph and is capable of dealing efficiently with functional blocks. Experimental results will show the effectiveness of the method.
Multivariate analysis at switching points between different types of muscle contractions
Authors: Kiryu Tohru , Satoh Hitoshi , Saitoh Yoshiaki
Published: July 2007

The biomedical signal often is affected by the anatomical structure, the method of measurement and the analytical approach which makes it difficult to determine the feature of the change only by observing the signal. Then it is important to analyze the biological activity comprehensively from the biomedical signals measured through multiple channels or from the multiple parameters estimated from a single biomedical signal.

From the viewpoint of the analysis of a long‐term biomedical signal, one of the most important indices is the switching point of biological activity. In the analysis of the economical indices, the prediction of earthquakes, and the weather forecasts, it is usual in practice to estimate the switching point for the trend from the time‐series data.

The goal of this study is to estimate the switching point of the behavior of the biological system from the multiple time‐series. The statistical properties of the switching point are investigated as the preliminary study. Four evaluation parameters are estimated from the surface electromyogram of the tibialis anterior muscle and the eigenvalue time‐series is determined from the multiple evaluation parameter time‐series by Karhunen‐Loéve (KL) expansion. The results showed that two eigenvalues λ1, and λ2 approached each other near the switching point between the different muscle contractions and only λ1 exhibited a large value at other phases. The distribution of the principal components also showed a change near the switching point. The forementioned tendency was observed in approximately 55 percent of five trials for 10 subjects.
The structure of elimination‐type algorithms for a class of fixed‐point problems on graphs
Authors: Tamai Tetsuo
Published: July 2007

It is known that many kinds of problems, including as typical examples the shortest path problem studied in the Operations Research and the dataflow analysis problem treated in the compiler technique, can be formulated uniformly as a fixed‐point problem on graphs.

This paper deals with elimination‐type algorithms for solving such problems. First, a unified formulation of the problem is presented and then two categories of elimination‐type solution methods are identified and classified by the elimination order and its meaning on graphs. One class is characterized as maintaining a spanning tree and the other as maintaining a maximal acyclic graph in the upper triangular matrix. The former is efficient specifically when applied to reducible graphs. This approach is reexamined from a new viewpoint. The latter is a method newly proposed by the authors and is applicable to general irreducible graphs and has practical features.
A 2‐D IIR neural hybrid filter for image processing
Authors: Muneyasu Mitsuji , Tsujii Satoshi , Hinamoto Takao
Published: July 2007

A two‐dimensional (2‐D) IIR neural hybrid (2DINH) filter is proposed for image processing. This 2DINH filter consists of the cascade connection of a 2‐D IIR linear filter followed by a neural filter. The proposed filter can be applied to smoothing for the images corrupted with Gaussian noise and/or impulsive noise and to edge detection for the images corrupted with Gaussian noise.

The parameters of a neural filter are adjustable by a learning algorithm to adapt itself to the property of an image to be processed. Finally, some examples are given to illustrate the utility of the proposed filter.
Two‐terminal nets via minimization through dynamic programming for partitioning of terminals
Authors: Fujiyoshi Kunihiro , Kajitani Yoji
Published: July 2007

In the routing in VLSI and printed circuit board (PCB) using the multilayered board, a routing technique is considered to reduce the number of vias produced in the routing. It is shown that the problem to determine the routing and layer assignment, to minimize the number of vias without considering the constraints of the line width and the line spacing, is NP‐hard even if the net is restricted to be the two‐terminal net. On the other hand, the following polynomial‐time algorithm is proposed.

Let the number of continuous intervals of terminals not containing the local net that can cover all terminals be δ (by local net is meant a net with both ends in the same interval). Then there exists a polynomial‐time algorithm when δ is 2 and the number of layers k is a constant or when k is 2 and δ is a constant.

This paper proposes a polynomial algorithm based on the dynamic programming which can handle both δ and k as parameters. Furthermore, a method also is proposed in which the partition into intervals is arbitrary and the local net can be contained. In addition, the total number I of the local nets can be handled as a parameter; I and δ are in a trade‐off relation. A method is discussed which solves the problem with minimum complexity in terms of the time estimated by the proposed method.
Identification of impulse responses by wavelet transformation
Authors: Maeda Hajime , Kitagawa Takashi , Kodama Shinzo
Published: July 2007

The wavelet transform is a signal transformation technique in which the information in the time and frequency domains can be obtained simultaneously within the range of the uncertainty principle. In this paper, identification of impulse responses is performed using the wavelet transform.

First, the system identification problem is studied by using the wavelet theory. It is shown by a numerical example that the high‐frequency components of the signal can be separated in the time domain from the noise provided the weighting function is chosen suitably. Finally, the role of the weighting function is discussed theoretically.
A new reference signal for evaluating the quality of speech coded at low bit rates
Authors: Asanuma Naomi , Nagabuchi Hiromi
Published: July 2007

This paper proposes a reference signal for use in evaluating the speech quality of low bit‐rate coded signals. The proposed signal is generated by adding a simulated low bit‐rate coding distortion signal to the original signal. This low bit‐rate coding distortion signal is modeled with both spectrum envelope distortion and additive white noise so that the simulated coding distortion signal is synthesized using both linear predictive coding (LPC) parameters derived from a signal whose spectrum envelope is distorted by spectrum‐shaped noise and by an LPC prediction error signal with added white noise. The simulated‐signal parameters, the amount of spectrum‐shaped noise and white noise, approximate the average characteristics of low bit‐rate coding distortion signals. Experimental results show that the proposed reference signal suppresses variability in evaluation scores and improves their reproducibility in repeated assessment tests.
A numerical calculation for some nonlinear optimal control problems with a terminal constraint using synthetic Riccati transformation and its applications to the manipulator control problem
Authors: Cai Dawei , Yamaura Hiroo , Shidama Yasunari
Published: July 2007

This paper describes a new numerical calculation algorithm for the nonlinear quadratic optimal problem with nonlinear terminal constraint. Synthetic Riccati transformation proposed earlier by the authors is utilized to solve the forementioned problem.

The state differential equation is changed into two differential equations with respect to the two substates vector selected from the state vector. Then, based on the maximum principle and Kronecker's product, two differential equations with respect to the adjoint variables can be derived. To solve the forementioned differential equations, synthetic Riccati transformation is introduced to obtain a Riccati differential equation and an accessory differential equation. Thus, we can calculate the initial values of the adjoint variables by solving Riccati equations backward in time. The convergence condition about this algorithm also is provided.

As the application of this algorithm, an attempt is made to apply it to an optimal trajectory control problem for a two‐link manipulator. As the result of the simulation, it is confirmed that the algorithm not only has a performance of both fast convergence and high computation accuracy but also is not subject to the selection of the normal parameter for computation.
Speech recognition using phoneme HMM constrained by frame correlation
Authors: Takahashi Satoshi , Matsuoka Tatsuo , Minami Yasuhiro , Shikano Kiyohiro
Published: July 2007

One of the problems with the hidden Markov model (HMM) in performing speech recognition is that the local transition information of the feature vectors is not incorporated into the mechanism of the model and the model is not constrained by transitions of the feature vectors. Thus, the output probability distribution never changes during recognition. Furthermore, all transitions between the vectors that have high probabilities are allowed even if those transitions did not appear in the training data.

This paper proposes a bigram‐constrained HMM that uses correlations between two frames to constrain the feature distributions of a speaker‐independent HMM to the region most appropriate for the speaker. Since the output probability of the bigram‐constrained HMM is a conditional probability restricted by the feature vector of the previous frame, the output probability changes dynamically at each frame depending on the feature vector of the previous frame. Constraining the feature distribution makes it possible to reduce the overlapping of feature distributions between different phonemes which improves recognition performance.

Previously, we proposed the discrete bigram‐constrained HMM which is based on the combination of a discrete speaker‐independent HMM and the VQ‐code bigram. We showed that it performed better than conventional speaker‐independent HMMs. In this paper, the strategy is extended to the tied‐mixture bigram‐constrained HMM and the continuous bigram‐constrained HMM to obtain better recognition performance. These three types of HMMs are formulated and evaluated by phoneme recognition in continuous speech.
An adaptive control for linear uncertain multiinput‐multioutput systems with robust performance
Authors: Maki Midori , Hagino Kojiro
Published: July 2007

This paper proposes an adaptive controller design method for linear multiinput‐multioutput systems with unknown parameters, an accurate model of which is not available. The proposed adaptive control scheme results in the prevention of system performance deterioration caused by the parameter uncertainties. In the proposed method, it is not necessary to estimate unknown parameters and/or to adjust the controller parameters.

First, a candidate for an approximate model to describe the uncertain parts of the plant is introduced and a target model which the controlled system should track is constructed based on the known nominal system and this approximate signal. Next, this tracking problem is changed to the linear quadratic (LQ) control one for the augmented system. This target trajectory is determined automatically to be close to the optimal response for the nominal system. It is shown that the asymptotic stability of the resulting total system is ensured if certain stability conditions are satisfied. In addition, an observer‐based adaptive control method and the stability of the combined plant‐observer‐controller system also are discussed when not all the states can be measured.
A realization method for an ARMA lattice filter with reduced number of coefficients
Authors: Haseyama Miki , Nagai Nobuo , Miki Nobuhiro
Published: July 2007

This paper proposes realization methods of two kinds of low sensitivity ARMA lattice filters which can perform frequency‐weighting model identification with input estimation and low sensitivity of their filters. Using the proposed realization method, the filter with the fewer coefficients than the previous filter can be obtained. Since the calculation costs for the realization of the filter are reduced, the proposed realization methods are significant. Furthermore, assuming that the ARMA lattice filters have low sensitivity, however, this paper shows that the proposed ARMA lattice filters have low sensitivity by simulations, which is important for practical implementation of filters.