bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of smoothed group delay spectrum distance measure in speaker‐independent speech recognition
Authors: Umezaki Taizo , Singer Harald , Itakura Fumitada
Published: July 2007

The smoothed group delay spectrum distance (SGDS) measure is evaluated in speaker‐independent recognition experiments. First, the appropriate level of smoothing of the group delay spectrum (GDS) is investigated by adding noise, etc., to the input speech. Then a comparison with the speaker‐dependent case is made. An experiment is reported in which, for low amplitude parts of speech (e.g., unvoiced speech), the standard (LPC) distance measure is used in the interframe distance calculation instead of the SGDS distance measure. This method prevents a loss of recognition accuracy due to too strong an emphasis on certain spectral elements and a consistently high recognition accuracy can be achieved.

Finally, evaluate the SGDS distance measure is evaluated where the GDS is represented in the spectral domain as a discrete Fourier transform (DFT) of the LPC coefficients. In comparison to the SGDS which was calculated by weighting the LPC cepstrum co‐efficients, computation time and memory space can be reduced without loss of recognition accuracy. Furthermore, a low bit quantization of the GDS is reported and a high recognition rate is achieved with only 32 bits per frame.
Design of 2‐D separable‐denominator digital filters using impulse response grammians
Authors: Hinamoto Takao , Toda Hideki , Yamaguchi Ryuji
Published: July 2007

A technique is developed for designing 2‐D separable‐denominator digital filters in the spatial domain. First, a given 2‐D FIR digital filter is realized in a canonic form by the Roesser model whose transfer function is separable in the denominator. Then, the reduced‐order model is obtained using eigenvalue‐eigenvector decomposition on the impulse response Grammians derived from the realization.

The proposed technique utilizes the impulse response Grammians considered here for 2‐D separable‐denominator digital filters, which are extensions of those proposed for single‐input/single‐output 1‐D linear systems. The stability of the resulting filter is always guaranteed. Finally, two numerical examples are given to illustrate the utility of the proposed technique.
Some properties of sequential‐association type neural networks
Authors: Yanai Hirofumi , Sawada Yasuji
Published: July 2007

Association is a fundamental aspect of information processing in neural networks. In order to elucidate the relationship between sequential association capabilities and the constituent elements of a binary‐output neural network model, we discuss here the response characteristics of elements (neurons) and the relationship between the adaptation (learning) rule for connection strengths (synapse weights) and sequential association capability. We discuss how sequential associations depend on the element‐characteristic, for example, the role of self‐connections in sequential associations of correlated patterns.

For adaptation rules which do not depend on the adaptation state of the network, we consider one based on a multiple of the current activation of an element (basically the Hebb rule) and one which is a multiple of the change in activation. The former rule has high capability in ideal circumstances, but we show that the latter rule is more robust. There have been many papers concerning the case in which the qualities of the patterns to be stored are known a priori, but here we also discuss flexibility (robustness) toward patterns which differ from those which are expected.
Study of the superiority of generalized linear interpolation approximation
Authors: Kida Takuro , Mochizuki Hiroshi
Published: July 2007

Consider a set of waveforms whose Fourier spectra are band‐limited within a certain frequency band. We assume that the weighted Lp integrals (1<p< +∞) of the Fourier spectra are bounded with respect to a given weight function. We present a method which optimally approximates the original waveform contained in the above set with respect to an appropriate measure of error. We use a series of sample values of the outputs obtained when the waveform passes through a given finite number of linear time‐invariant filters.

Here, we establish a theorem which shows that there exists a waveform among all those waveforms whose sample values at the sample points are all zero, whose error is a maximum at some arbitrary fixed time t. Further, under the condition that p = 2 and the sample values, which are in general not all zero, are given, we prove that the upper limit of approximation error is proportional to the maximum of absolute value of the approximation error described above. As a result, it is shown that as long as the set of waveforms and the measure of approximation error mentioned above are adopted, the proposed linear approximation method is superior to all other approximation methods even including, for example, non‐linear signal processing using the same sample values. Further, at the end of this paper, we show that our argument can be applied to more general sets of waveforms.
Functional information extraction from combinational circuits
Authors: Ohmura Masahiko , Yasuura Hiroto , Tamaru Keikichi
Published: July 2007

This paper proposes a technique of functional information extraction which transforms design description at the logic circuit level in the LSI design process to a description at functional level. This technology is considered to be a powerful means of logic design verification similar to the circuit extraction technology already in practical use for layout design verification. Moreover, by automatically generating function description language from given circuit description, it can be used in functional and fault simulations and is useful in reusing circuits.

An extraction technique of logic and arithmetic functions of combinational circuits is investigated herein. As internal representation of logic functions, binary decision diagrams are used for efficient treatment. For extraction of arithmetic functions, a technique of first extracting logic functions, and then representing them by arithmetic expressions is used. This technique has a characteristic that the same function description is obtained from circuits with the same functions even though their circuit structures are different. Therefore, functional information extraction independent of circuit structure can be done.

This paper describes first the extraction of logic functions, which is the basic technique, and then explains the arithmetic function extraction technique. Finally, some concrete examples are evaluated.
Automatic design of a parallel/pipelined VLSI architecture for signal processing
Authors: Yokoyama Yutaka , Miyanaga Yoshikazu , Tochinai Koji
Published: July 2007

This paper discusses the system for automatic design of the parallel/pipelined VLSI architecture based on the signal processing algorithm. A new design language is introduced into the proposed system. The language is defined so that the time variable used in the signal processing algorithm can easily be described. The system has a high modularity, and the modules can be combined into a hierarchical structure. By this scheme, the algorithm with a high complexity can easily be described.

The algorithm inputted to the system may contain a backward time‐flow of the delayed data as well as a complex hierarchical structure, which makes it difficult to execute the data‐flow graph obtained directly from the algorithm by the parallel/pipelined structure.

From such a viewpoint, this paper adopts the following procedure. The data‐flow graph is derived from the given algorithm. A sufficient parallelism and a highly efficient pipelined mechanism are extracted from the obtained graph. Then the parallel processing architecture is designed. As an example, a parallel/pipelined architecture is designed for a simple adaptive signal processing algorithm. The result is compared with the traditional design examples, and it is shown that the efficient data‐flow architecture is derived.
Road noise barriers as sound radiation systems
Authors: Kagami Shin , Moriyoshi Akihiro , Fukai Ichiro
Published: July 2007

Road traffic noise has become a significant societal problem and the noise barrier as one remedy is studied acoustically. Traditionally, as a theoretical background for installing the noise barrier, the diffraction theory of the acoustic wave by a screen has been employed. In this paper, however, the noise barrier and the road structure on which a vehicle is a noise source are treated as one acoustic radiating system. By means of the boundary element method useful for an open‐region problem, a two dimensional analysis is carried out.

From the results of the analysis with the cross‐sectional shape of the noise barrier and the frequency as parameters, it is found that a resonance is generated for a shape with parallel faces and the noise may be spread a large distance away in conjunction with the diffraction at the edge of the noise barrier. If an unrealistic containment is not expected and a horn shape is employed, the noise can be radiated upward in the direction normal to the road surface and the diffraction does not become significant. The frequencies studied were 150 to 300 Hz which are bothersome to the human ears.
A design of wide‐bandpass filter using transmission lines and lumped capacitances
Authors: Sekine Toshikazu , Nakamura Takashi , Yokokawa Senji
Published: July 2007

This paper discusses a design method for the small‐sized wide‐bandpass filter, which is a circuit composed of distributed‐constant transmission lines and capacitors. In this method, the wide‐bandpass filter is designed as follows.

The lumped‐constant LC lowpass filter is used as the prototype. To derive the mixed circuit containing transmission lines and capacitances from the prototype circuit, although approximately, the cascade section of the mixed circuit is transformed into the equivalent π‐type circuit. Then, a new frequency transformation is considered to arrive at the wide‐bandpass filter. The mixed circuit designed by this method contains cascade transmission lines and the parallel short stubs, and the cascade transmission lines have the same length. The condition for minimizing the approximation error in the design is discussed. The range of the bandwidth ratio that can be designed is examined, and the usefulness of the proposed design method is verified by experiment.
Chaos in a four‐dimensional autonomous circuit with two diodes
Authors: Nishio Yoshifumi , Mori Shinsaku , Inaba Naohiko
Published: July 2007

This paper proposes a 4‐D autonomous circuit represented by a constrained equation containing two small parameters. Various chaotic phenomena generated in this circuit are rigorously analyzed. This circuit contains two diodes and their ON resistance corresponds to the parameter. Here, an ideal case is considered in which the ON resistance of the diode is 0. In such a case, the circuit equation can be represented by a 2‐D equation in a piecewise manner and the Poincaré map can be extracted as a 1‐D map. The shape of this map is that of logistic map. By means of the latter, the generation of the period‐doubling bifurcation and chaos observed in the circuit experiment can be rigorously explained.
Computational complexity of the homotopy method for calculating solutions of strongly monotonic resistive circuit equations
Authors: Makino Mitsunoai , Oishi Shin'ichi , Kashiwagi Masahide , Horiuchi Kazuo
Published: July 2007

A priori estimation is presented for a computational complexity of the homotopy method applied to a certain class of hybrid equations for nonlinear strongly monotonic resistive circuits.

First, an explanation is given as to why a computational complexity of the homotopy method cannot be a priori estimated for calculating solutions of hybrid equations in general. In this paper, the homotopy algorithm is considered in which a numerical path‐following algorithm is executed based on the simplified Newton method. Then by introducing Urabe's theorem, which gives a sufficient condition guaranteeing the convergence of the simplified Newton method, it is shown that a computational complexity of the algorithm can be a priori estimated when applied to a certain class of hybrid equations for nonlinear strongly monotonic resistive circuits whose domains are bounded.

This paper considers two types of path‐following algorithms: one with a numerical error estimation in the domain of a nonlinear operator; and one with a numerical error estimation in the range of the operator.
Enhanced circuit simulation: Expectations, problems, implementation, and integration
Authors: Saleh Resve A. , Inoue Takahide , Ido Sachihiko
Published: July 2007

During the late 60s and throughout the 70s, the field of circuit simulation has advanced in step with the increase in the use of analog integrated circuits. The general purpose circuit simulator SPICE was released in this period. During the 80s, in addition to pure analog circuits, digital and mixed analog‐digital VLSI circuits also saw dramatic increases in usage. In this paper, we will discuss the roles that manufacturers are coming to expect that circuit analysis techniques will play in the development of VLSI circuits. Specifically, we will consider the limitations that general purpose simulators like SPICE have and enhancements needed in the future. We will consider these limitations by specifically considering problem analysis methods developed for each limitation. Finally, we present ideas for future work.
Acquisition of internal representation by multilayered perceptrons
Authors: Irie Bunpei , Kawato Mitsuo
Published: July 2007

One of the characteristics of the PDP model (multilayer perceptron with backward error propagation learning) is thought to be its ability to automatically find a mapping between inputs and outputs based on input‐output vector samples describing that mapping. However, since in the mapping the values of representative points are determined by table lookup, and the values of other points are determined by interpolation between them, it can be viewed as one type of Memory Based Reasoning. On the other hand, it is thought that the PDP model has the ability to extract features from the input vector.

In this paper, the forementioned two points are investigated completely and it is demonstrated that entirely different results are obtained when the internal representation differs, even if the input data are exactly the same. It is stipulated that information processing in the PDP model is a process that carries out a transformation which represents the input vector distribution in an optimal metric space (internal representation) and interpolates that metric space. This internal representation acquisition capability is demonstrated by means of a simple simulation.
A fuzzy selection method for generated equivalent logic circuits
Authors: Wakabayashi Satoshi , Ishikawa Hiroyuki , Dang Ryo
Published: July 2007

In the design of logic circuits, it is not always true that the circuit constructed by the designer is the optimal one. From such a viewpoint, this paper proposes a method in which the first designed circuit is expanded backwardly, i.e., from the output back to the input, and more than one equivalent circuit of the same function is resynthesized and the one best satisfying the requirements is determined and adopted.

In the proposed method, a fuzzy reasoning is introduced in the decision process. In this scheme, such requirements as the delay time, power consumption and the chip area are handled by the fuzzy reasoning. A selectability index known as “selection criterion value” is given to each generated circuit, and the objective logic circuit is selected according to this index.

Such requirements as delay, etc., have different units and are often in a trade‐off relation. Therefore, these requirements are represented as relative values and are considered as circuit selection parameters in the fuzzy reasoning. Such parameterization enables easy understanding of the features of each circuit. It is easy also to decide which of the parameters of the trade‐off relation is to be emphasized in the selection process.
Performance analysis of disk allocation methods for cartesian product files by using error‐correcting codes
Authors: Ito Minoru , Kasami Tadao , Kataoka Mituteru , Fujiwara Toru , Okui Jun
Published: July 2007

The Cartesian product file is an efficient method of handling the partial match queries to retrieve a record from a file, which has the specified values for the specified attributes. The optimal processing efficiency for the query is realized in an environment where multiple disks with parallel access are employed by allocating the Cartesian product file among the disks in a distributed way so that the buckets which may contain the record satisfying the specified condition are read uniformly from the disks.

Recently, Faloutsos and Metaxas proposed a method whereby the Cartesian product file is allocated to the multiple disks using the error‐correcting code. In this paper, using their method of allocating the Cartesian product file in the multiple disks, the following is presented: (1) the sufficient condition for the queries so that the processing efficiency is strictly optimal; 92) the necessary and sufficient condition for the code that realizes the allocation with the strictly optimal efficiency for any queries; and (3) the expression for the average response time for the query by which we can easily compute the average response time when the weight distribution of the code (or that of the dual code) is known. Through several examples, it is shown that the average processing time determined from the expression is very close to the theoretical lower bound.
Estimation errors of volterra kernels measured by use of nonwhite input
Authors: Yokoyama Makoto , Watanabe Atsushi
Published: July 2007

It is well known that employment of nonwhite input in system identification often causes large estimation errors. While the mechanism of inducing these errors has been well understood for linear system identification, it has not been made clear yet for nonlinear systems.

This paper analyzes this mechanism for nonlinear system identification with Volterra functional series models. A vector space approach gives a clear physical interpretation of the error generation from a viewpoint of the excitation intensity of the input against the identified system. Based on this analysis, new algorithms of reducing estimation errors are proposed.
Estimation of impulse response by using a nonwhite input—analysis of estimation errors by geometrical approach
Authors: Yokoyama Makoto , Watanabe Atsushi
Published: July 2007

When the ordinary least‐square method is applied in the estimation of the impulse response of the linear system using a nonwhite input, the result is affected greatly by the observation noise and the error in the numerical calculation, and the accuracy of the estimation is greatly deteriorated.

This paper presents a mathematical analysis based on a geometrical approach for the error generation mechanism and provides a clear physical description from the standpoint of the system identification. It is shown that the nonwhite input has the following problem.

The excitation turns out to be weak for the linear system in which the impulse response vector corresponds to the eigenvector for a small eigenvalue of the autocorrelation matrix. This weakness of the excitation is the major cause of the deterioration of the estimation accuracy in the ordinary least‐square method.

Based on those results, a new physical interpretation is given to the eigenvalue truncation method and the regularization method, which are already proposed as improvements of the ordinary least‐square method. The proposed error analysis can also be considered as the basic theory which can be applied not only to the estimation of the impulse response, but also to the parameter estimation of the transfer function model and the design of the optimal input for the identification.
Effects of finite register length in the fast hartley transform
Authors: Furuya Ken'Ichi , Date Hikaru , Fukudome Kimitoshi
Published: July 2007

This paper discusses the effect of finite register length on the computation accuracy of the fast Hartley transform (FHT) and derives a theoretical statistical expression for the mean‐square computation error. Theoretical proofs are presented which show that: (i) the computation error of a fixed‐point FHT is proportional to the square of the number of data (N); (ii) the computational error is proportional to N if scaling is used to prevent an overflow in the fixed‐point FHT; (iii) the computational error is proportional to log N in the case of the floating‐point FHT; and (iv) the computation error is halved by increasing the register length by 1 bit. An experiment was conducted to verify those properties.
Finite element analysis of focusing transducers and their responses
Authors: Tsuchiya Takao , Kagawa Yukio , Yamabuchi Tatsuo
Published: July 2007

For the accurate field analysis of focusing ultrasonic transducers, an acoustic lens or a waveguide system including a piezoelectric driving resonator and its radiation field must be fully considered. The finite element method is applied to analyzing the sound field from the acoustic lens driven by a piezoelectric disk. The steady‐state sound field is examined for the lens system of some configurations. First, a lens‐water coupled system is considered; and then the vibration of the piezoelectric resonator is also included. It is shown that the presence of the piezoelectric vibrator affects the focusing capability or resolution. The time‐dependent field is then demonstrated by the use of an inverse Fourier transform technique for an electric impulsive excitation. Comparison is made with the steady‐state response for the focusing capabilities. It is confirmed that the present technique is useful for the computer‐aided design of focusing transducers.
A method of two‐dimensional spectral analysis using the wigner distribution
Authors: Suzuki Hiroshi , Kobayashi Fuminori
Published: July 2007

Wigner distribution (WD) has recently attracted attention as a powerful tool for time‐varying signals analysis and several applications have been proposed. WD is calculated as the Fourier spectra of a signal with special preprocessing. The preprocessing allows the frequency resolution to be better than that of Fourier transform (FT). However, this preprocessing causes WD to generate interference terms and more complicated aliasing compared to FT. To cope with these problems, WD is usually calculated using analytic signals. In one‐dimension, the method of deriving analytic signal is unique. However, in two‐dimensions (2‐D), several methods have been proposed.

This paper presents the reason for 2D‐WD to generate aliasing and interference for negative frequency components and its solution. Based on the discussion, a new analytic signal for 2D‐WD is proposed together with a method of new spectral analysis using the signal. The proposed method offers higher frequency resolution and no interference term for negative frequency components, as well as no aliasing, providing characteristics similar to WD. By using this method, spectral analysis for low frequencies can be realized with small‐sized windows.
A method for selecting the most suitable pitch from some candidates utilizing its time continuation
Authors: Ogihara Akio , Yoneda Shojiro
Published: July 2007

Pitch frequency is a basic characteristic of the human voice, and pitch extraction is one of the most important studies for speech recognition. This paper describes a method for selecting the most suitable candidate from candidates (pitch candidates) obtained by the short‐range autocorrelation function. The selection is done utilizing the time continuation which is realized by that history of pitch candidates at previous frames referred to with a referential matrix. In addition, an improved result of pitch extraction is obtained by introducing restraints of double‐pitch and half‐pitch. The pitch extraction was performed for three males and three females. The proposed method improves the percentage of correct pitch from 64.86 to 91.06 percent.
Effects of aluminum thickness on temperature characteristics of surface acoustic wave devices on the quartz LST‐cut
Authors: Murota Masao , Hirano Tetsuya , Shimizu Yasutaka , Lam C. S. , Holt D. E.
Published: July 2007

One of the highly stable quartz substrates for surface acoustic devices is the LST‐cut using the leaky surface acoustic waves. It has been reported that the temperature dependences of the center frequency and the insertion loss are affected by the thickness of the electrode film.

In this paper, with a view to finding the relationship between the optimum cut angle and the thickness of the electrode film, the temperature dependences of the center frequency and the insertion loss have been studied theoretically and experimentally in the case where the cut angle and the thickness of the electrode film are varied. Good agreement has been found between the theoretical and experimental results if the thickness of the electrode film is taken into account.

The relationship between the cut angle and the thickness of the electrode film for the temperature dependences of the center frequency and the insertion loss has been found theoretically and presented in the form of contour plots. It has been demonstrated that devices with superior performance can be obtained by controlling the cut angle and the thickness of the electrode film.
A method of hazard detection by five‐valued logic simulation based on the TRF delay model
Authors: Kang Min Sup , Deguchi Hiroshi , Shirakawa Isao
Published: July 2007

This paper proposes an efficient method to detect the hazard existing in the logic circuit using the five‐valued logic simulator. The proposed method is effective in logic verification for the combinational and asynchronous and sequential logic circuits as well as the verification for the hazard (race).

Using the proposed method, the timing of the logic circuit is analyzed, including the rise/fall delay considering the signal transition time. The hazard is detected based on the output of the gate and the scheduled time. Also discussion is a method of event cancellation, which is a problem in the delayed simulation. Through the results of experiments using several circuits, the proposed algorithm is shown to be useful.
Coefficient sensitivity analysis for block‐state realization of state‐space digital filters
Authors: Tsunekawa Yoshitaka , Shida Junichi , Kawamata Masayuki , Higuchi Tatsuo
Published: July 2007

This paper presents an analysis of the frequency characteristics of the coefficient sensitivity in the block‐state realization. The expression for the coefficient sensitivity is derived first, and the following properties are shown. In contrast to the usual state‐space realization, the coefficient sensitivity in the block‐state realization has the periodicity with period (2π/L), where L is the block length. There is also a symmetry for the response in a period. Then the following property is shown in the coefficient quantization in the block‐state realization. The peaks of the coefficient sensitivity, which usually appear only at the end of the passband, appear many times iteratively in other frequency ranges, resulting in a particular coefficient quantization error. This point must be considered in the design of the filter by block‐state.

A measure for the coefficient sensitivity is defined anew to evaluate the coefficient sensitivity over the whole frequency range. It is shown that this measure of the coefficient sensitivity is an extension of the ordinary state‐space realization. The expression of the measure is given by the state covariance matrix of the subfilters for the elements of transfer function in the block‐state realization, i.e., the L‐input/L‐output system, together with the noise matrix. Finally, a computation example is shown.
A design method of LQ regulator by fuzzy set theory
Authors: Hagino Kojiro , Ohbayashi Tokuji
Published: July 2007

The most important problem in the design of control systems by the LQ regulator theory is the absence of guidelines to determine the weighting coefficient matrices Q and R in the quadratic objective function. In practice, a designer determines Q and R by trial‐and‐error while observing the step response waveform. A designer modifies Q and R and observes the obtained response waveforms. While making a compromise with design specifications for a considered system, a designer tacitly sets the tolerance for response waveform in the sense that he can tolerate the deviation from the design specification.

In contrast to the traditional method of design, this paper formulates the tolerance for a response waveform conceived by a designer for design specifications as a fuzzy constraint using fuzzy set theory. A method of design is proposed in which the fuzzy representation for the weighting coefficient matrices is constructed for given design specifications, and the satisfactory solution (Q*, R*) to satisfy the designer's standard is determined. An application for the aircraft is shown.
Software reliability growth model with continuous error domain—application of a linear stochastic differential equation
Authors: Tanaka Hiroaki , Yamada Shigeru , Osaki Shunji , Kawakami Shin‐Ichi
Published: July 2007

This paper considers the software error detection process in the testing phase, which is the final stage of the software development. The process is modeled by a stochastic process with a continuous changing variable. Employing a new mathematical technique based on the stochastic differential equation, a new software reliability growth model is constructed.

First, the traditional basic differential equation, which describes the average behavior in time of the number of errors, is extended to the Itǒ‐type stochastic differential equation, and the probability distribution of the solution process is investigated. Then, using the derived distribution, several reliability assessment measures are derived.

Finally, the unknown parameters of the model are estimated based on the actual test data, and the stochastic property of the temporal variation of the errors remaining in the software is examined numerically. Using MTBF (mean‐time between failure), which is the important reliability assessment measure, the problem to determine the release time of the software is discussed.
A synthesis of switched capacitor inductance simulation circuit using voltage followers
Authors: Ono Toshio
Published: July 2007

Voltage followers are used for the switched capacitor (SC) circuit simulating the ungrounded inductance based on the bilinears‐Ztransform. The operation is confirmed by experiments. In the circuit configuration, it is pointed out that the block diagram often used in the derivation of the SC inductor complicates the circuit and the control clock and a new block diagram is proposed. The circuit derived by this method is simple since the control clock has two phases and the spreading of the capacitance value is only 2. Further, the circuit is not affected by the parasitic capacitance caused by the substrate‐side electrode of the integrated capacitor which typically affects the characteristics significantly.

Although two voltage followers are needed for realization of one inductor, it can be considered that effectively one inductor is constructed with one voltage follower if the adjacent SC resistance and SC inductor are shared with a voltage follower. It is described that the spread of the capacitance value in the entire filter can be made smaller than other SC inductors when this SC inductor is used in the SC filter. Simplification of the circuit with this filter is investigated.
Application of modified off‐axis spectrum to speech recognition under noisy conditions
Authors: Nakagaki Atsushi , Miyanaga Yoshikazu , Tochinai Koji
Published: July 2007

This paper introduces a peak enhancement method using an off‐axis spectrum which is used in peak picking. It also considers its advantages and problems for the application of speech recognition. An off‐axis model modified to be suitable for speech recognition is proposed. The modified off‐axis model is realized by combining a peak emphasis model and a peak repressed model. The modified off‐axis model can control the peak bandwidths and the slope of its spectrum by operating two parameters. The values of the parameters are determined adaptively to each sample by a stability test. In addition, some results of experimental speech recognition under noisy conditions are described and the efficiency of the method is discussed.
VLSI‐oriented design method of asynchronous sequential circuits based on one‐hot code and two‐transistor and logic
Authors: Cho Kyong‐Rok , Asada Kunihiro
Published: July 2007

This paper proposes a new method of synthesis for a CMOS LSI‐oriented asynchronous sequential circuit with the two‐transistor AND logic structure, using the one‐hot code for the internal state assignment. The assignment of the state by the one‐hot code is executed uniquely, independently of the properties of the state‐transition table. The CPU time for state assignment, which has been a problem, can be ignored.

The critical race‐free property, which is then a problem, is solved by a 4‐FET set/reset flip‐flop which stores the state variable and the drive circuit for the flip flop, not the internal code assignment. The set and the reset driving circuits have the AND logic circuit structure, where two transistors are placed (with the state variable and the external input as the gate inputs) on each conduction path. The synthesized circuit is hazard‐free. It realizes a pseudo‐CMOS operation without static power consumption.

Comparing the method proposed in this paper with other methods of synthesis, it is compact and especially suited to the large‐size asynchronous sequential machine (with 40 or more cells in the row‐column product of the state transition table).
A parameter optimization method for electronic circuit design using stochastic model function
Authors: Lu Jin‐Qin , Adachi Takehiko
Published: July 2007

This paper presents an optimization procedure using the stochastic model function, aiming at the application to the optimization of the circuit constant in the integrated circuit. The optimization of the circuit constant is formulated as a minimization problem for the objective function derived from the circuit response under the specified condition.

In the method presented in this paper, the model function is constructed which approximates well the objective function, and the objective function is minimized by minimizing the model function. The features of the method are that the algorithm is simple, the number of evaluations of the objective function is small, the result depends less on the initial value, and the minimum of the objective function can be determined with a high accuracy. The method is evaluated using the standard test function, and it is verified that all minimum values of the objective function can be determined with a high accuracy with fewer number of calculations of the objective function. The optimization procedure is applied to two circuit examples: the analog control circuit and the inverter chain. The result is satisfactory and the usefulness of the presented optimization procedure in the circuit design is demonstrated.
Construction of codes on arbitrary plane curves
Authors: Kamiya Norifumi , Miura Shinji , Imai Hideki
Published: July 2007

In 1981, Goppa established an epoch‐making method for constructing a code utilizing the theory of algebraic curves [1]. This is called the algebraic curve code. This paper develops the theory on an arbitrary curve, which may contain singular points and discusses the method of constructing the code.

The method employed in this paper is to eliminate the singular point by applying the transformation called blowing‐up and to construct the code on the nonsingular model. The number of genes of curves can be derived simultaneously. It is made easy to derive the bases of the linear spaces L(G) and Ω(G‐D), as in the case of the nonsingular curve.

The algebraic curve C considered in this paper is the irreducible projected plane curve or the algebraic curve which is obtained by gluing irreducible affine plane curves. In this case, the nonsingular model of C can also be represented as a gluing of irreducible affine plane curves. Then the method is applied to the hyperelliptic plane curve on which the number of rational points achieves the Hasse‐Weil bound or certain hypernonelliptic plane curves. It is shown that the precise structure of the code can be examined.
Switched network analysis based on final value theorem of Laplace transform
Authors: Suetsugu Tadashi , Mori Shinsaku , Mizutani Hikaru , Tanaka Mamoru
Published: July 2007

This paper proposes a new method of analysis in the modified nodal analysis of the switched network. In the proposed method, the limit of the switching resistancerfor 1/∞ or ∞ is replaced by the limit of the variable “s” of Laplace transform fors→ 0. Then by applying the final value theorem of the Laplace transform, the solution of the network equation immediately after switching is derived as the limit fort→ ∞ of the virtual state equation.

By this transformation based on the final value theorem of the Laplace transform, the limiting operation of the switching resistance can be transformed into the iterative calculation of the product of the nonsingular matrix, which does not depend on the switching resistance, and a vector.

In this new method, the coefficient matrix of the backward Euler method in the numerical integration of the virtual state equation is always nonsingular. This makes it possible to designate the next switching pattern without a particular algorithm, even in the singular problem where the network equation becomes singular for a certain switching pattern.

When the state before the switching is the actual solution, as in the SC network, this method can derive the discontinuous solution which jumps from one state to the next state. Since the coefficient matrix of the backward Euler method is always nonsingular, the inverse matrix lemma can be applied to the calculation of the inverse matrix, which can be executed by lowering the order of the matrix from the given matrix to the actual order of the switched pattern.
Integration environment to invoke CAD tools efficiently
Authors: Miyazaki Toshiaki , Hoshino Tamio , Endo Makoto
Published: July 2007

This paper describes an integration system for VLSI design tools and their interface builder. The main advantage of this system is its unique process control mechanism. Once VLSI designers specify their tasks by using a flowchart‐based graphic editor, the system could handle the design process and maintain the design data produced by each tool. In addition, the system features several interface building tools and subroutine packages that readily integrate new design tools into the system environment. The system was conceived to provide a unified interface for designers and to manage CAD tool invocation to improve design turnaround time.
Evaluation and analysis of coded speech quality
Authors: Nakayama Takeshi , Futagami Tohru , Takida Keiji , Kodama Kazuyuki , Kawasaki Zenshiro
Published: July 2007

Rating scale data for evaluating coded speech quality by the mean opinion score (MOS) are factor‐analyzed to show the possibility of extracting rich information from them. Two factors, softness‐shrillness and clearness‐noisiness, are extracted. Factor scores expressing a kind of multidimensional scale of speech quality are related to several physical parameters of speech samples, e.g., differential spectral distortion, phase distortion, and dissonance. Individual subject differences in evaluating speech quality are extracted as the factor loadings. It is found also that speech specialists and nonspecialists place different weights on different factor axes.
Analysis of quantization errors in digital control systems using floating‐point arithmetic—considering computational order in controller
Authors: Okada Kazuho , Kuroe Yasuaki
Published: July 2007

The floating‐point representation is employed widely in the digital control system due to its features of large dynamic range and high accuracy. However, a sufficient study has not been made on the quantitative evaluation of the quantization error because of the difficulty of the analysis.

From such a viewpoint, this paper considers the general digital control system and discusses the evaluation method for the control error and the performance deterioration of the control system due to the quantization in the A‐D and D‐A converters, as well as the arithmetic operations in the controller. The difference equation for the error of the state of the digital control system is derived, and the quantitative evaluation of the error (i.e., the mean and the variance) is proposed based on the equation.

It is noted that there is a freedom in the order of computation in the control operation in the digital controller, and the computation error depends on the order of computation. Consequently, a matrix is newly defined to specify the order of computation, and a method is proposed for the analysis of the control error considering the order of computation.

In the proposed method, the error can be evaluated for the general digital control system without specifying the object of analysis. The usefulness is demonstrated by a numerical example.
An analysis for steady‐state response of nonlinear systems with sinusoidal inputs
Authors: Ichikawa Satoshi , Goto Tsutomu
Published: July 2007

Numerous studies have been made to analyze the input/output relation of the weakly nonlinear system by applying the theory of Volterra series. When this theory is applied directly to the analysis, a complex multiple integration must be calculated. On the other hand, it is shown in this paper that the solution can be derived by a systematic calculation using multiplications and additions if the input is restricted to the sum of sinusoidal waves and only the steady‐state output is considered for the system represented by a nonlinear equation or a circuit equation. A detailed algorithm is presented, which is called the “nonlinear steady‐state method”.

The purpose of this paper is to demonstrate the usefulness as well as the problems of the nonlinear steady‐state method through examples. The first step is to derive the algorithm for the analysis, which can produce a result equivalent to that of the theory of Volterra series. The Duffing equation is used as an example of the system represented by a nonlinear differential equation. Then, as an example of the system represented by a circuit equation, the method is applied to the analysis of the linear antenna with a nonlinear load. The application of the method is inevitably limited due to the condition that the system is weakly nonlinear and the input is the sum of a finite number of sinusoids. However, the result seems to indicate that the method is very useful when those conditions are satisfied.
A synthesis of pipelineable wave digital filters by scattering matrix factorization
Authors: Watanabe Eiji , Mogi Yoshiaki , Nishihara Akinori
Published: July 2007

This paper proposes a synthesis of low‐sensitivity digital filters which are pipelineable and have simple structures. Their sensitivity characteristics are similar to those of wave digital filters. The synthesis of these filters is attained by factorizing paraunitary scattering matrices derived from given z‐domain transfer functions without referring to analog filters. The synthesized structures are the T‐cascade connection of fundamental sections which are constructed by using series and parallel sections of wave digital filters.

The proposed synthesis method can realize any given IIR transfer function, while previous methods which synthesize T‐cascaded structures can realize only the amplitude response of any given transfer function. In addition, the method can realize the transfer functions of which the order of their denominator is higher than that of their numerator including FIR transfer functions.
An algorithm for generating finite two‐dimensional real number sequences with low autocorrelation sidelobes
Authors: Ohue Kenji , Aibara Tsunehiro
Published: July 2007

When the spread‐spectrum technique or smear technique is applied to the two‐dimensional data such as the image data, which have the two‐dimensional array structure, it is important to apply the two‐dimensional numerical sequence that minimizes the sidelobe component of the autocorrelation function.

This paper proposes a new method of generation, where the two‐dimensional complex exponential function is used as the generating function and a finite two‐dimensional real‐number sequence with a sharp autocorrelation function is derived from the two‐dimensional Fourier expansion coefficients.

As the first step, the phase condition is derived for the Fourier expansion coefficients of the generating function to be real. It is shown that the infinite two‐dimensional real‐number sequence constructed by the forementioned infinite number of Fourier expansion coefficients is an uncorrelated sequence. Then it is shown that by using the proportional constant of the phase function as the parameter, a finite two‐dimensional real‐number sequence with the autocorrelation function with arbitrary evaluation function value can be derived.

Finally, a generation example of the finite two‐dimensional real‐number sequence is shown, demonstrating that the finite two‐dimensional real‐number sequence with a very sharp autocorrelation can be generated by the proposed method.
Analysis of impedance‐gas pressure characteristics of a tuning‐fork‐type quartz resonator with the rough surfaces by using fractal model of turbulence
Authors: Ito Hideaki , Nakazawa Mitsuo
Published: July 2007

The impedance vs. gas pressure characteristics of a tuning‐fork‐type quartz resonator with rough surfaces have been studied experimentally and theoretically. On the quartz resonator with rough surfaces, the flow of the gas is separated so that the laminar flow is changed into a disturbed state of fluid considered as turbulence. It is assumed that this turbulence induces the surface friction resistance larger than that of a smooth surface. The change of impedance due to the turbulence can be formulated by introduction of the fractal model of the turbulence describing the energy cascade process into the mixing length theory by Prandtl. The obtained theoretical formula for the impedance variation is proportional to the square power of the pressure and agrees well with the experiments.
Measurement of sound and vibration at the lips, nostrils, and pharynx wall in speech utterance and simulation of sound leakage from the oral cavity to the nasal cavity in nonnasal sounds
Authors: Suzuki Hisayoshi , Nakai Takayoshi , Dang Jianwu
Published: July 2007

Sounds and vibrations at the lips, the nostrils, and skin near the pharynx are measured separately in an anechoic room using a specially designed soundproof box with three microphones and three accelerometers. It is found that the radiation from the nostrils is not negligibly small even if the nonnasal sounds were spoken and that the nostril sound in a close vowel /i/ is stronger than that in an open vowel /a/. A buzz bar of voiced plosives is found to be radiated from both the nostrils and skin near the pharynx.

Based on these findings, a vibrating plate model is introduced to simulate the acoustic coupling between the oral cavity and the nasal cavity through the velum. To simulate the radiation of the buzz bar of voiced plosives, an active inflation of volume of the pharynx cavity is introduced and the relationship between the inflation rate and the sound radiation is shown.