bluuebunny/crossref_metadata_2025 huggingface dataset:
Obtaining an ideal associative memory by means of a simple hysteresis network
Authors: Jin'No Kenya , Saito Toshimichi
Published: July 2007

The hysteresis net is considered in which all crossconnections are uniform and the control paameters are restricted to two. an analysis is presented concentrating on the case where the state specified by the system is a stable equilibrium. A complete result is obtained for the type and number of the stable equilibria of the systm, as well as the convergence region for each stable equilibrium.

As an application example of the hysteresis net, an associative memory is proposed which has the ideal memory‐recall function for the information. the associative memory is composed of three units which are the hysteresis net. the initial value generator, and the output circuit. It has the function that almost completely solves the problems in the traditional associative memory. In other words, all the contents which are prespecified as desirable are securely memorized and the false stable memory content is not produced. When incomplete information is given, the desired memory with the smallest Hamming distance is securely recalled. the proposed associative memory can very easily be implemented, and the desired content can always be stored using the switches.
A procedure for satiosfiability problems based on the partial instantiation technique
Authors: Yamamoto Masahito , Ohuchi Azuma , Ohyanagi Toshio
Published: July 2007

When no function symbols occur in a first‐order predicate formula, there exists a procedure to decide the satisfiability of the formula. Examples of such procedures are the method based on Robinson's resolution principle and the method based on the partial instantiation technique by Jeroslow.

This paper considers the case where the formula is in clausal form and no function symbols occur in it and proposes a satisfiability decision procedure based on the partial instantiation technique applicable to the considered case. the procedure is based on the partial instantiation technique, as in Jeroslow's method, but aims at the following aspects by utilizing the formula being in clausal form: (1) Davis‐Putnam's method is used in solving the satisfiability problem in the propositional logic; (2) the rapid expansion of the formula can be suppressed by expanding the formula with the clause as the unit; and (3) the number of unifications is reduced. the proposed method is compared to Jeroslow's method and the method based on the resolution principle, and then the effectiveness is demonstrated.
Reduction of specific absorption rate (SAR) in the human body by perfect conducting shield
Authors: Nakamura Takasi , Tokumaru Shinobu
Published: July 2007

As application of electromaganetic waves have inceased, effect on the human body has became a concern .Especially,these effects are significant problems for researchers who,because of their occupation , receive high does of electromagnetic illumination.

In this paper, for researchers dealing with high‐power electromagnetic waves, a method is proposed for reducing the absorption power by means of a perfectly conducting shielding. As a fundamental stage, the reduction effect of the specific absorption rate (SAR) when a plane wave is incident on a cylindrical human model with a perfectly conducting shield is calculated and discussed. the effectiveness of the shield is presented.
Secret sharing schemes based on combinatorial designs
Authors: Song Youjin , Kurosawa Kaoru , Satoh Takashi , Tsujii Shigeo
Published: July 2007

In secret‐sharing schemes, a secret s is encoded as v1, …, vn, and vi is distributed to member Pi. By the access sets, we mean exactly those subsets of {Pi} which can recover the secret s. Previous secret‐sharing schemes have utilized the methods of polynomial interpolation [20] and projective geometry [6], among others. In this paper we show how to obtain secret‐sharing schemes from combinatorial designs, including orthogonal arrays (OAs) and t ‐ (v, k, 1) designs.
Improvement of convergence speed for subband adaptive digital filter using the multirate repeating method
Authors: Kiya Hitoshi , Nishikawa Kiyoshi , Ashihara Koji
Published: July 2007

The subband adaptive system, where the idea of the filter bank is applied to the adaptive filter, has a feature that a higher‐order adaptation can be reduced to lower‐order adaptations. the reduction of the order of the adaptive filter is related closely to the number of channels and the decimation ratio. the order of adaptive digital filter (ADF) is decreased greatly when the number of subbands is increased, and the decimation ratio is increased up to the maximum value. Then, however, the number of coefficient‐updates per unit time is decreased, which results in the deterioration of the convergence speed.

From such a viewpoint, this paper discusses a method to improve the convergence speed, which is deteriorated in the subband adaptive system, due to the decimation. the idea of the proposed method is to utilize effectively the data which have been discarded in the decimation process and to improve the convergence speed. It is called the multirate repeating method.

As the first step, the multirate repeating method is applied to the conventional subband adaptive system and the convergence speed is improved. Then a subband adaptive system is introduced in which the multirate repeating method can be utilized more effectively. As a result, a faster convergence is realized while retaining the ADF order‐reduction effect, which is an advantage of the subband adaptive system.
Mathematical considerations and improvement on the fuzzy vector quantization‐based hidden markov model
Authors: Tsuboka Eiichi , Nakahashi Jun'Ichi
Published: July 2007

Two new types of fuzzy vector quantizationbased/hidden Markov models (FVQ/HMM)—multiplication‐type and addition‐type—are formulated to remove a mathematical inconsistency in conventional FVQ/HMMs proposed by Tseng et al. Experiments show the MTFVQ/HMM gives the best recognition rate among VQ‐type HMMs. Lettingytbe an observation vector at timet, C1, …,CMbe clusters to whichytis classified andsibe thei‐the state of HMM, we show that MT‐FVQ/HMM is derivable by defining the occurrence degree ofytatsito be the negative of the Kullback‐Leibler divergence ofa posterioriprobability distribution {P(C1|yt), …P(CM|yt)} froma prioriprobability distribution {P(C1|si), …,P(CM|Si)}.
An analysis of pulse propagation dynamics in asynchronous chaotic neural networks
Authors: Ichinose Natsuhiro , Aiharai Kazuyuki
Published: July 2007

In this paper, we analyze some possible functions of networks where delays of pulse propagation and asynchronous events of pulse occurrence are considered, on the basis of a model of asynchronous chaotic neural networks. First, the model is proposed and response characteristics of the single neuron are numerically analyzed. Second, it is shown that the network model with loop structure can select time interval sequence peculiar to the network structure even if random noise is superimposed.
Theoretical analysis of nonlinear interaction of intense electromagnetic wave and plasma waves in the ionosphere
Authors: Matsumoto Hiroshi , Hirata Hisashi , Hashino Yoshitaka , Shinohara Naoki
Published: July 2007

It is well known that refraction, Faraday rotation, scintillation and absorption of microwaves take place when a microwave passes through an ionospheric plasma. However, when the amplitude of the microwave is large, nonlinear interactions occur with plasma in addition to these plasma interactions with a small signal microwave. Various phenomena not conceivable for weak microwaves used in communication can take place. Especially, it is predicted that the three‐wave resonance, which is the most fundamental nonlinear wave‐wave interaction, can be applied to the nonlinear wave‐wave interaction between the plasma and a large signal microwave.

In this paper, the generating condition of the electrostatic plasma wave phenomena excitated in the plasma medium by a large signal electromagnetic wave is theoretically investigated and the nonlinear coupling coefficient between the large signal electromagnetic wave and the electrostatic plasma wave is derived.
Chaotic oscillations in dissipative and second‐order direct‐form II Digital Filters with a 2′s Complement Adder
Authors: Kawamata Masayuki , Sasaki Shinji , Higuchi Tatsuo
Published: July 2007

This paper studies the chaotic oscillations in a dissipative system generated by a second‐order directform II digital filter with a 2′s complement adder. the locus of this chaotic oscillation is absorbed into the parallel lines comprising the Cantor‐like set on the state space. In this paper, with respect to the chaotic oscillation, the initial value dependence of the locus, the output distribution, the power spectrum, the correlation function, and the fractal dimensions of the locus on the state space are investigated as the fundamental nature of the chaos. Also, by considering this filter as the two‐dimensional mapping, the mechanism generating the Cantorlike attractor is studied. From this study, it is shown that the 2′s complement adder characteristic has functions for stretching and folding of the state space causing the chaos. Also, the coefficient dependence of the Cantorlike attractor is studied and the relationship between the fractal dimensions of the locus and the coefficient are presented.
A note on lattice quantized coded modulation method
Authors: Minami Noriaki , Wakasugi Koichiro , Kasahara Masao
Published: July 2007

There is the expectation that lattice quantizers that use lattice basis vectors will be capable of source coding at high rates and low distortion. the application of lattice theory in coded‐modulation, on the other hand, is now at a practical stage (as can be seen in such applications as general telephone networks and mobile communication modems). Research into source coding schemes that use this type of lattice quantization has up to date been considered independently from research into lattice coded‐modulation. In this paper, a unified coding approach is considered. A new method is proposed that realizes in an integrated fashion coded‐modulation schemes that have recently received a great deal of attention as well as source coding methods suitable for data with frequency distributions typical of those of images. Then, as a specific example, a combined coding method is considered in detail that is realized by using the structure of the lattice to bridge lattice quantization and QAM modulation steps. As a result, it is shown that (i) it is possible to reduce the average modulation power of the entire system by performing a simple mapping that depends on the frequency of use of the lattice points; (ii) that maximum likelihood decoding can be more easily implemented since combined coding is accomplished in a way that preserves the structure of the lattices; and (iii) a simple, nearly optimum technique is proposed and it is shown that this system's average modulation power can also be reduced. Furthermore, simulation experiments are performed that clearly demonstrate the effectiveness of a system that combines E8 and A16 lattices with 256‐QAM modulation.
An equivalent transformation of multiterminal nets to two‐terminal net‐sets in the topological via minimization problem
Authors: Fujiyoshi Kunihiro , Kajitani Yoji
Published: July 2007

In via‐minimization in toplogical routing on ak‐layer, an equivalent transformation of at‐terminal net to a collection of two‐terminal nets is considered. an equivalent transformation to a special structure of twoterminal nets, which is called a two‐terminal net‐body, is presented for the case when available vias are throughhole vias andt⩽kand for the case when available vias are adjacent‐layer vias andt= 3. the key issue is the proof that the routings of thet‐terminal nets in optimum routing are classified into a few fixed number of cases with respect to the division of the layers and that each net is equivalently replaced with a two‐terminal netbody.
Optimal design method of separable‐denominator two‐dimensional digital filters based on a genetic algorithm
Authors: Kawamata Masayuki , Imakubo Jun , Higuchi Tatsuo
Published: July 2007

This paper proposes the optimal design for the separable‐denominator two‐dimensional digital filter, using the genetic algorithm (GA). the design proposed is for the specification in the frequency domain. the simple GA, which is the most basic among GA, is used in the proposed optimal design. the parameters of the transfer function of the separable‐denominator twodimensional digital filter are encoded into bit sequences, and then GA is applied to design the filter. By the use of the separable‐denominator transfer function, the stability of the filter is completely guaranteed.

The approximation error of the proposed method is compared to that of the conventional method through design examples. the convergence of GA is discussed. It is shown that the proposed optimal design can easily cope with the modification of the design specification of the two‐dimensional digital filter. It is shown also that the filter can be designed using the maximum error or the absolute error sum as the error evaluation function in addition to the mean‐square error.
Fast coding algorithm for iterated transformation theory‐based coding by multiresolution tree search
Authors: Kawamata Masayuki , Nagahisa Masaki , Higuchi Tatsuo
Published: July 2007

The digital image coding technique, iterated transformation theory‐based coding (ITTBC), requires an enormous amount of encoding search time compared to other coding techniques because of the requisite roundrobin iterative code search procedure. the computational complexity of previously proposed ITTBC methods is on the order of O(N2), where N is the number of blocks contained in the image. an ITTBC method that uses a multiresolution tree search to reduce code search time is proposed here. In the proposed method, a search tree is constructed by subsampling and this search tree is used for code searches. the images stationed at the nodes of this search tree are formed from blocks extracted from the original image where, depending on their height in the tree, different subsampling rates are used. Thus, the constructed tree has different resolutions at different heights. By using this type of multiresolution tree search for code searches in the proposed coding method, the computational complexity of code searches becomes O(N log N), which is greatly reduced compared to previously proposed ITTBC methods. From experiments with the proposed coding method, it is shown that only a 0.5‐dB p‐pSNR performance loss is experienced while the encoding time of the proposed method is reduced to 14 percent of that required by previously proposed ITTBC systems.
A unifying treatment of general gradient adaptive digital filter and convergence analysis with arbitrary inputs
Authors: Chao Jinhui , Kawabe Shinobu , Tsujii Shigeo
Published: July 2007

The unifying treatment of a general gradient adaptive algorithm studied here is based on the principles of minimum mean square method and instrumental variable method by formulating the general oblique projection algorithm, including finite impulse response (FIR) and serial‐parallel infinite impulse response (IIR)‐type configurations. the oblique projection algorithm of low‐order past‐value data space is derived in which the dimension of past‐value data space can be easily adjusted, including the least mean square (LMS) method, learning‐identification method and gradient instrumental variable method (GIVE). Next, the new analysis model which describes the convergence process of general gradient algorithm is shown and the convergence conditions are indicated for the first and second moments with arbitrary inputs. It is found that this condition is more severe as compared with the white input. Moreover, the process of convergence of these conditions is studied by simulation.
A standard cell global routing algorithm with net selection for over‐the‐cell routing
Authors: Koide Tetsushi , Suzuki Takeshi , Wakabayashi Shin'Ichi , Yoshida Noriyoshi
Published: July 2007

In the detailed routing for VLSI standard cell layout design, the over‐the‐cell channel routing, which utilizes the over‐the‐cell region as the routing region, has been proposed. In this design method, after determining the net assignment to each channel in the global routing step, the track assignment both in channel and on over‐the‐cell regions is performed by an over‐the‐cell channel router. However, conventional global routing algorithms do not assume over‐the‐cell channel routing but conventional channel routing. Therefore, the minimization of channel density does not always successfully lead to the minimization of the final channel height.

This paper presents a new global routing method for standard cell layouts to determine global routes for each net in both channel and over‐the‐cell regions simultaneously. the standard cell layout design system GLORIA based on the proposed algorithm is developed, and the experimental results compared with the conventional global routing method that performs the over‐the‐cell channel routing after global‐routing with Timber Wolf‐SC4.2c are reported.

Experimental results showed that the proposed routing algorithm can route about 18.4 percent fewer number of tracks than the conventional routing method, and the effectiveness of the proposed method is shown. the experimental results of applying the proposed method to the three‐layer routing layout model also are presented.
Two‐phase controlled switched‐capacitor impedance simulation circuits using one voltage follower
Authors: One Toshio
Published: July 2007

Simulation cirucits for inductors and frequency dependent negative resistance (FDNR) based on switched capacitors (SCs) have been propsed. However, there has been no example reported in which a simple configuration of one voltage follower is used as an amplifier and a binary clock as the simplest control clock is used for operation. In the present research, it is pointed out that the conventional cirucit uses a delay circuit operated with a complicated clock. Such a configuration is simplified by using a fundamanetal delay circuit operated with a binary clock. It is shown that the simulation results obtained from the SC circuit analysis program SWITCAP agree with the theoretical results. Also shown are the experimental results with individual components and the effect of the parasitic capacitances.
A design method for parallel nonlinear adaptive digital digital filters using neural networks
Authors: Yahagi Takashi , Cao Jianting , Lu Jianming
Published: July 2007

Linear adaptive digital filters are applied to various fields for their simplicity in the design and implementation. Considering many kinds of nonlinearities inherent to preactical systems, however, nonlinear adaptive filtering will be more desirable. In this paper, we present a design method for parallel nonlinear adpative digital filters using multilayer nonrecursive neural networks. Linear adaptive digital filters can be replaced by nonlinear adaptive digital filters with the advantage of obtaining better accuracy of estimation. Furthermore, the nonlinear adaptive digital filter is extended to parallel nonlinear adaptive digital filters which reduce the computations of each filtering system, especially when a high‐order nonlinear adaptive digital filter is necessary.
A formant frequency modification algorithm dealing with the pole interaction
Authors: Mizuno Hideyuki , Abe Masanobu
Published: July 2007

When a formant is modified based on the pole of the AR model, a problem arises due to the interaction between the pole to be modified and other poles such as the apparent elimination of the formant, if the frequency of the considered pole simply is modified. to solve this problem, the method proposed in this paper uses the spectral intensity at the pole frequency as a new feature parameter and the spectral intensity at the pole after the frequency modification is corrected to the desired value by iterative processings.

To examine the effectiveness of the proposed method, an experiment was conducted in which a phoneme in a word is replaced into the same phoneme in a different environment, and then the formant frequency is modified by the proposed method in order to restore the original speech. the speeches before and after the modification are compared in terms of the cepstral distance (CD) from the original speech, and it is verified that the proposed method is effective in the modification of the formant. an attempt is made to solve the formant discontinuity problem at the concatenation point in waveform based speech synthesis‐by‐rule and to modify the formant frequency accompanying the modification of the fundamental frequency using the proposed method. It was verified as a result of experiment that the speech after formant modification is better than the speech before modification, indicating that the proposed method is useful in improving the quality of the synthesized speech.
Design of linear‐phase M‐channel perfect reconstruction finite impulse response filter banks using lagrange‐newton method
Authors: Nagai Takayuki , Ikehara Masaaki
Published: July 2007

Filter banks are separated roughly into paraunitary and nonparaunitary ones. Paraunitary filter banks are excellent and have several good characteristics, but it is difficult to design such a system. This research focuses on nonparaunitary filter banks and presents a design method for the linear‐phase (LP) M‐channel perfect reconstruction (PR) finite impulse response (FIR) filter banks. In this method, M‐2 analysis filters are arbitrarily designed and then the remaining ones are optimized using the Lagrange‐Newton method. Using the proposed method, PR filter banks with arbitrary order can be designed easily. Furthermore, the design method that considers the pairwise‐shift symmetry is shown and such a system is easy to design.
Development of a petri net‐based simulator for factory automation systems
Authors: Nagao Yoichi , Nakano Shinichi , Higuma Katsutoshi , Kumagai Sadatoshi
Published: July 2007

This paper presents K‐NET, a general‐purpose simulator for factory automation (FA) systems, that stimulates a system model based on Petri net. First, net elements for modeling, the model editing function, and the simulation function are explained; and then a planning system is described for automatic storage/retrieval systems that utilize the K‐NET simulation function, which automatically generates a simulation model, animates the system behavior, and evaluates system performance. Finally, a distributed simulator for large FA systems and an example application of the tool are described.
A new F‐H embedding algorithm for input encoding
Authors: Abe Motohisa , Ishimaru Masakatsu , Ariyoshi Hiromu , Shirakawa Isao
Published: July 2007

This paper presents a new encoding algorithm based on the face hypercube embedding for satisfying given input constraints. the algorithm works for a constraint relation matrix derived from the sets of the input symbols grouped for each output symbol independently and finds the encoding through row‐by‐row (group‐by‐group) cover assignment. A cover is found by the extension of a core cover generated from the magnitude estimations and adjacent relations of the currently known covers. Each cover is formed to be a single cube; and, if it is unsuccessful for specified code length, then the encoding length is extended. the experimental results indicate that this encoding technique has advantages over well‐known existing methods in the quality of encoding.
Vehicle behavior at a merging section of an automated transit system with a randomly varying arival rate
Authors: Hamamatsu Yoshio , Kikuchi Shinya
Published: July 2007

This paper considers the merging secton of the automated transit system which is a new transportation method. the behavior of the vehicle when the arrival rate of the vehicle of one of the lines varies is analyzed by the Markov chain technique. In past studies of the merging section, the case in which the arrival rate of the vehicle is kept constant in time is the one considered most of the time. When, however, some control is exerted on the vehicle traffic before the merging section, the arrival rate of the vehicle at the merging section will not be kept constant. This paper aims at a strategy conidering the arrival rate variation of the vehicle and analyzes the situation in the merging section when the ensemble of the arrival from one of the lines exhibits a variation of the state as a Markov chain. to analyze the vehicle behavior in such a model for the merging section, the state variable is defined and formulated considering the classes of the ensemble of the arriving vehicle. From the analysis results, the effect of the variation of the vehicle arrival rate on the queueing delay through the merging section is described.
Controlling chaotic discrete‐time systems via nonlinear feedback
Authors: Mori Hironobu , Ushio Toshimitsu , Kodama Shinzo
Published: July 2007

Recently, occurrences of chaos have been reported in many engineering systems and most of these occurrences are unfavorable phenomena which used to be controlled. This paper proposes two methods for the stabilization of arbitrary unstable periodic orbits embedded in chaos attractors existing in nonlinear discrete‐time systems using nonlinear feedback. First, we proose a method based on a property of contracton mappings. Next, we propose another method using exact linearization via nonlinear feedback. In both methods, differentiability of the controlled systems is not required. Moreover, feedback ned not be reconstructed in target periodic orbits.
Theorem proving based on the partial instantiation technique
Authors: Yamamoto Masahito , Ohuchi Azuma , Ohyanagi Toshio
Published: July 2007

For studies toward the automated theorem proving, various methods and strategies have been presented based on the resolution principle proposed by Robinson in 1965. Most of the theorem‐proving systems at present are based on this resolution principle. In constrast to this, Jeroslow proposed the partial instantiation technique in 1988. the method proposed by Jeroslow, however, has a problem in that only the formula not containing function symbols is considered and the efficiency is low since the clause form is not assumed. the authors improved Jeroslow's method. A procedure was proposed where satisfiability is decided for the formula of the clause form not containing function sysmbols, and the effectiveness of the method is demonstrated.

This paper extends the above procedure and proposes a theorem‐proving procedure so that the formula containing function symbols can be handled. A proof is given that the proposed procedure is complete. A comparison experiment is executed, and the effectiveness of the proposed procedure is investigated.
Maximally permissive controllers for controlled time petri nets
Authors: Takae Akiteru , Takai Shigemasa , Ushio Toshimitsu , Kumagai Sadatoshi , Kodama Shinzo
Published: July 2007

Standard Petri nets are an untimed logical model. But timing information is important for real‐time control of discrete event systems. This paper studies state feedback control of concurrent discrete event systems modeled by controlled time Petri nets. It is assumed that a control specification is given in terms of markings. A maximal element of the set of controllers achieving a control specification is called a maximally permissive controller (MPC). In general, the MPC is not necessarily unique in controlled time Petri nets. In this paper, we present a necessary and sufficient condition for the unique existence of the maximally permissive controller. Then we derive a closed form expression of the unique MPC if it exists. Moreover, we synthesize a unique MPC for a simple manufacturing system.
An algorithm for a maximum clique of the intersection graph of isooriented rectangles on a cylinder
Authors: Kizu Takashi , Araki Toshiro , Kashiwabara Toshinobu
Published: July 2007

A set ℱ of rectangles is considered which are placed on the surface of a right cylinder such that two of their sides are parallel to the axis of the cylinder. A graph G = (V, E) is called a rectangle‐on‐a‐cylinder‐intersection graph with a model ℱ, if the vertices of G can be put into a one‐to‐one correspondence with the rectangles in ℱ, such that two rectangles in ℱ have nonempty intersection if and only if two vertices corresponding to them are connected by an edge in G. In this paper, it is shown that given an ℱ, a maximum clique of the corresponding rectangle‐on‐a‐cylinder‐intersection graph can be obtained in polynomial time, by repeatedly using an algorithm for finding a maximum clique of a circular‐arc graph. Furthermore, an algorithm is constructed which, given a dynamic set C (initially empty) of circular arcs which changes as arcs are added to or deleted from C, finds a maximum clique of the circulararc graph corresponding to C in O(m(d + 1)) time every time C is changed (here m is the number of arcs and d is the number of arcs intersecting the added or deleted arc). It is also shown that, using this algorithm, an algorithm can be constructed for finding a maximum clique of a rectangle‐on‐a‐cylinder‐intersection graph in O(n(n + e)) time (n is the number of vertices and e is the number of edges).
An adaptive filter with adaptation to nonuniformly spaced samples
Authors: Sakai Miwa , Aizawa Kiyoharu , Hatori Mitsutoshi
Published: July 2007

A novel adaptive filter is proposed that adapts to the sample spacing as well as to the tap weights. Although in adaptive digital processing, the tapped‐delay line usually has uniformly spaced taps, with the spacing equal to symbol period or a fraction of symbol period, an adaptive filter with a few taps should be adaptively arranged for nonuniform spacing for better convergence as the sampling timing varies. The conventional nonuniformly spaced filters are not adaptively changed or not arranged under the constraint of the acceptable meansquare error. In this paper, a least‐mean square (LMS)‐type algorithm is derived in which an adaptive filter adaptively changes the amount of delay, as well as the filter coefficients. The performance of the proposed algorithm is investigated by computer simulation.
A statistical decoding of simultaneous burst and random errors beyond the BCH bound using reed‐solomon codes
Authors: Horiguchi Toshio
Published: July 2007

This paper proposes a stochastic decoding method that can correct the composite errors beyond the BCH bound. It does this by tolerating that some of the composite errors cannot be corrected. Considering the case where the t‐error correcting Reed‐Solomon code with designed distance d = 2t+1 on GF(q) and code length n(⩽q‐1), it is shown that the proposed decoding method can correct the simultaneous composite errors composed of a single burst error of length v(<2t‐1) or less and t′(⩽t‐(1/2)v) or less random errors, with the probability not less than 1‐(n/(q‐1)2t‐v‐2t′).(1/t′). In other words, by setting v and t′ in the range tvt′<2t, the proposed method can correct the simultaneous composite errors beyond the BCH bound with the above probability. Then, a stochastic decoding system and a decoder circuit configuration are proposed based on the remainder decoding, and it is shown that a high‐speed stochastic decoder can be realized by a relatively small‐scale circuit when t′ is small (0⩽t′⩽2∼3).
Mathematical formulation of electron beam processing systems by stochastic variational inequalities
Authors: Ishikawa Masaaki
Published: July 2007

This paper is concerned with the mathematical formulation of electron beam processing systems. the mathematical model of stochastic electron beam processing systems proposed here takes randomness of material into consideration. In electron beam processing, the melting surface moves over time as a result of evaporation and melting material so that the melting surfaces become a so‐called free boundary. Therefore, the problem considered in this paper is among the free boundary problems, e.g., the Stefau problem. the difference between the problem proposed here and the Stefan one is that the term related to the intensity of the electron beam appears in the problem proposed by the author. For a system with a free boundary, variational inequality is an analytical method. Since this paper deals with the stochastic system with the free boundary, a system is formulated by the stochastic variational inequality of a new type, which is an extension to the stochastic system of a usual variational inequality. the uniqueness and existence properties of the solution of the stochastic variational inequality are also studied. the mathematical security of the model of the stochastic electron beam processing system is guaranteed.
Quantitative evaluation of trigger‐pulse reflected waves in supersonic extracorporeal shock‐wave lithotriptor
Authors: Nakamura Osamu , Morita Nagayoshi , Okazaki Kiyoshi
Published: July 2007

As one method to prevent the mis‐shot in the supersonic extracorporeal lithotriptor, there is a system in which the trigger pulse is emitted to ensure that a calculus exists in the focal region. This paper discusses the propagation of the trigger pulse within the body in this type of system, using the finite‐difference time‐domain method.

In this paper, the scattering and reflection of the pulse is analyzed when a calculus is placed in the focal region of the ultrasonic propagation paths. Then, a calculus is assumed to be shifted gradually from the focal region and the change of the reflection is examined in relation to the operation of the trigger‐pulse systems.

Finally, the case is considered where a calculus exists in the focal region and there exists a bony structure (called bone) near the pulse propagation paths. the propagation, scattering and reflection of the pulse is examined, and the effect of the position of the bone on the behavior of the trigger pulse is evaluated quantitatively and investigated.
Realization of two transfer functions with complex coefficients by a transfer function with hypercomplex coefficients
Authors: Ueda Kazuhiro , Takahashi Shin‐Ichi
Published: July 2007

This paper shows that two complex coefficient transfer functions can be realized by a single hypercomplex coefficient network, utilizing all four outputs of the hypercomplex network. the realization is considered for the case where the two arbitrary complex coefficient transfer functions do and do not have a common denominator. It is shown that the transfer functions can be realized by the hypercomplex coefficient network of the same order in the former case and by the hypercomplex coefficient network with the half‐order in the latter case. the realization of the transfer functions with the common denominator is interesting, but the general method to derive the transfer functions is not known.

From such a viewpoint, this paper proposes the discrete‐type Kautz approximation with the positive frequency as the domain of approximation, including the optimal pole determination algorithm. By this approach, two complex coefficient transfer functions with ann‐th‐order common denominator are derived from the two 2n‐th‐order real or complex coefficient transfer functions. the method can be considered as one that simultaneously approximates the amplitude and the phase. the proposed approximation method is an approximation only for the positive frequency domain, and the property of the analytic signal that the negative frequency component is zero can be utilized. As a result, the method proposed in this paper has the advantages that the degree of freedom in the filter design is enhanced and the sampling frequency can be halved. In addition, the network structure can be simplified.
Two‐dimensional adaptive filters based on the one‐dimensional recursive least squares algorithm
Authors: Muneyasu Mitsuji , Uemoto Eiji , Hinamoto Takao
Published: July 2007

This paper proposes a method for realizing two‐dimensional (2‐D) adaptive filters by applying a one‐dimensional (1‐D) recursive least squares (RLS) algorithm. First, by applying a 1‐D RLS algorithm along horizontal and vertical directions, a novel 2‐D adaptive algorithm is developed. It is shown that the amount of calculations in the proposed algorithm is less than that in the existing 2‐D RLS algorithm. Moreover, the convergence properties of the proposed algorithm and its relation to the conventional 2‐D RLS algorithm are investigated. A method for accelerating the rate of convergence of the algorithm usinga prioriestimation error also is described.

The proposed filter has good performance in nonstationary processes and the accuracy of convergence is better than that in the existing 2‐D adaptive filters based on the least mean square (LMS) algorithm. Therefore, the proposed filter is suitable for processing an image with strongly nonstationary characteristics. Finally, the utility of the proposed filter is illustrated by applying it to 2‐D system identification under a nonstationary environment as well as noise reduction of an image.
Proposal of a skill level index based on user's thinking time
Authors: Nakamura Yoshihiro , Kato Yasuyuki , Mitsunaga Yutaka
Published: July 2007

The time required to accomplish a task is the most common index of skill level. A learning curve that expresses the deductive process in relation to time needed is widely used. However, it does not always provide an accurate picture, because it cannot be used for a task that has an irregular form. and it cannot perform evaluations in real time during user operation. Moreover, because it is influenced by an error factor, it lacks precision. Studies have already been undertaken on a basic user adaptive interface. However, to increase its effectiveness and enable it to provide more intelligent support, it is necessary to consider the user's skill level. Thus, a skill level index is provided based on the user's thinking time. to put it more concretely, the authors looked at the time interval between one operation and the next. Using a statistical technique, we evaluated the skill level quantitatively. Experiments with test subjects showed that the proposed index coincides well with the subjectivity of the experimenter and the working time. the features of this index are that it does not depend directly on the content of the task, but on the user's cognitive performance. Therefore, this index can be used for a task with an irregular form and will provide real‐time evaluation by repeatedly gathering event data at regular intervals.
New sufficient condition of nonexpansive time‐delay time‐varying systems and its application to learning control
Authors: Yashiki Satoshi , Matsumoto Naoki , Takahashi Tohru , Endo Tetsuro
Published: July 2007

Recently, sufficient conditions for a time‐delay time‐varying (TDTV) system have been shown to be nonexpansive or bounded real (BR). Using this result, the sufficient conditions for stability of learning control for the TDTV system have been derived [2]. the characteristic of these sufficient conditions is independent of delay.

This paper considers the relation between these obtained conditions and the similarity transformation of a TDTV system, and derives new sufficient conditions of the nonexpansive TDTV system which are invariant under block similarity transformation. New stability conditions also are derived for the learning control of the TDTV system. the new sufficient conditions include the parameter of delay length explicitly, and ensure that when the given TDTV system satisfies the new conditions, every TDTV system which is similar to the given systems is nonexpansive. It also is shown that under a certain condition, the new sufficient conditions guarantee the nonexpansivity of TDTV system even when the value of the time‐delay length of a real TDTV system deviates from the values in the sufficient condition. Finally, numerical examples are given to show that the obtained stability conditions of learning control are valid.
An improvement in the pointer coding of LZ77 data compression method
Authors: Yokoo Hideotoshi
Published: July 2007

There are essentially two approaches in the Ziv‐Lempel code to be used in the data compression. They have already been proposed also as the improvements of the Ziv‐Lempel code, which can be considered as combinations of the two methods. This paper shows that by executing the combination, not only are advantages produced, but also the structure of the Ziv‐Lempel code is derived which realizes a more efficient coding. A precise data compression method is proposed based on the derived structure. the proposed method corresponds to an improvement of the LZ77 method. As the pointer information for the substrings for the coding the parameter corresponding to the length of the substring is encoded first, in contrast to most of the past methods. Then, utilizing the result, the coding method for the position of the reference substring is adjusted selectively. the proposed method is one method with the highest compession ability among the modifications of the Ziv‐Lempel code.
A method of extracting mosfet parameters with small model dependency using a common intermediate model
Authors: Kondo Masaki , Onodera Hidetoshi , Tamaru Keikichi
Published: July 2007

This paper proposes a method of extracting parameters which can systematically be applied to a large number of MOSFET models. the previous method for parameter extraction based on the numerical optimization has a problem in that the computation method for the initial value depends on the model and the method cannot easily be applied to various models.

In the proposed method, a simple intermediate model composed of a few parameters is introduced and the computation procedure for the initial value is decomposed clearly into the model‐independent part and the model‐dependent part. When the proposed method is applied to a new model, only the latter part should be considered. In other words, the computation procedure for the initial value is made systematic. the parameter extraction experiment is attempted for major MOSFET models included in the circuit simulator SPICE and the applicabilty of the proposed method, and the accuracy of the extracted parameters are verified.
View‐dependent and view‐independent properties in human object recognition
Authors: Gyoba Jiro , Yanagida Tamon , Akamatsu Shigeru
Published: July 2007

Psychophysical experiments were conducted in order to evaluate the possibility that both view‐independent and view‐dependent properties are involved in human object recognition. the results suggest that human prototypes of objects have descriptions that contain rich information on component structures but view‐independent properties are found only in limited ranges. Therefore, after these prototypes are activated, a verification process by rotation is considered necessary to check correspondence to observed views. In recognition experiments using familiar objects, multiple regression analyses revealed that the degree of activation of the prototype affected the percentage of correct responses and that the time taken by the verification process mainly determined reaction time. For recognition of novel objects with small component variations corresponding to within‐category differences, the verification process by rotation seems very important. In contrast, for recognition of novel objects with large component variations corresponding to between‐category differences in natural objects, the prototype activation process plays a major role, while the precise verification process seems to be unnecessary. Thus, the proposed two processes can reconcile contradictory points between the psychophysical experiments which show view‐dependence and view‐independence.
Computer‐aided communications by visualizing thought space structure
Authors: Sumi Yasuyuki , Ogawa Ryuta , Hori Koichi , Ohsuga Setsuo , Mase Kenji
Published: July 2007

There has been an increase in collaborative work among specialists from multiple disciplines in recent years. Accordingly, building methods and tools to facilitate communications in those collaborative projects has become an essential issue. This paper describes a method that helps people working cooperatively to form new concepts in areas such as science and engineering. The proposed method supports personal or group concept formation by visualizing the relationships between concepts and their microcontents, given by users, in a metric space. Showing individual spaces presented by communication support system (a tool implemented using this method) to individual users and merging them are useful in clarifying personal backgrounds and viewpoints.
A combinatorial consideration of the error‐correcting capability of difference‐set cyclic codes
Authors: Kobayashi Kazumasa
Published: July 2007

This paper discusses a theoretical method for estimating the error‐correcting capability (ECC) of difference‐set cyclic codes (DSCCs). DSCCs can be decoded by using majority logic decoding (MLD); however, variable threshold decoding (VTD) is often employed to improve performance. A combinatorial consideration of the ECC using MLD first must define the probability of failure to correct errors at each reference bit. Both the perfect recovery rate and the discrete probability density (DPD) of residual errors after an MLD processing are then calculated. the ECC achieved by using VTD equipped with two concatenated MLDs is estimated based on the DPD. the numerical estimations of the ECC are examined by comparing them with conventional computer simulation results. These results show that the calculated values conform well to the simulation values. the proposed method can be applied efficiently to test both error‐correcting chips and the design of the built‐in self‐test circuit for them. Results can also be applied to estimate the performances of new super‐long codes, to which little attention has been paid so far.
Design of finite impulse response transmitter and receiver filters for data communication system
Authors: Aikawa Naoyuki , Isomura Hitoshi , Ishikawa Tsuyoshi
Published: July 2007

Finite impulse response (FIR) transmitter and receiver filters for data transmission require both frequency domain and time domain approximation simultaneously. Previously, linear programming techniques have been used to design such filters; however, those techniques require many calculations and lengthy computation time. Proposed here is the design method of FIR transmitter and receiver filters for data transmission that uses the successive projections method. The design method of a matched filter pair is first described. It can have maximum signal‐to‐noise ratio (SNR) when Gaussian noise exists on the transmission line and where both the transmitter and receiver filters have the same amplitude response. Since the matched filter has double zeros in the stopband, it can also be used to derive the transfer function of a bandpass minimum phase filter. Then, the value of zero in the sampling interval is chosen such that total impulse response of the matched filter pair has zero intersymbol interference. A design method with constraint in time domain is thus described.
Metrics for syndrome decoding of convolutional codes
Authors: Tajima Masato
Published: July 2007

This paper derives soft decision metrics for syndrome decoding of convolutional codes. It is shown that, given a received sequence Z, syndrome decoding of convolutional codes can be seen as the problem of finding error sequence E. This sequence may be a possible cause of the syndrome sequence computed from Z and for which the joint probability μ(Z,E) is maximum. Then the soft decision metrics are derived by actually evaluating the probability μ(Z, E). In particular, a concrete representation of the symbol metrics for an AWGN channel is given. After expressing the derived metric in terms of the inner product, the basic properties of the metric for syndrome decoding are clarified and the similarity between the metrics for syndrome and Viterbi decoding are shown.