bluuebunny/crossref_metadata_2025_split huggingface dataset:
On detection of quantization noise in low level reproduction of digital audio system
Authors: Ebata Masanao , Maeda Kanako , Takada Kenji , Usagawa Tsuyoshi 
Published: July 2007

AbstractOn recent audio equipment, a wide dynamic range of nearly 100 dB is achieved by using 16 bit linear quantization. But quantization noise is still detectable, because relatively few bits are used to represent low‐level signals. When the signal is quantized directly, the quantization noise consists of harmonics of the source frequency. This quantization noise is detectable at 55 dB for a pure tone and at just about 40 dB for complex and modulated tones, if we assume that the maximum reproduction level is 120 dB. This harmonic distortion can usually be reduced by adding dither at quantization. When dither is added, the quantization noise becomes white noise and spreads over the entire frequency range. Experimental results indicate that at frequencies lower than 2 kHz, the detection level of quantization noise is raised by several dB when dither is introduced. But at about 4 kHz, the detection level falls because of the dither; in this case, the white noise induced by the dither seems to function as a detection cue.
Pole assignment for three‐dimensional systems using two‐dimensional dynamic compensators
Authors: Kawakami Atsushi 
Published: July 2007

AbstractThis paper discusses the pole assignment problem for the three‐dimensional system which is described by a state‐space model. The problem is to provide a feedback and input transformation using two‐dimensional dynamic compensators to the given three‐dimensional system. In this way, the denominator polynomial of the transfer function of the closed‐loop system coincides with the product of three one‐dimensional polynomials with roots in the unit circle.First, the three‐dimensional system is considered as a one‐dimensional one over a two‐dimensional rational functional field, and the desired pole assignment is realized by providing the two‐dimensional dynamic feedback and the input transformation. Concretely, the dynamic compensators for the feedbak system and the input transformation are regarded as two‐dimensional transfer functions. By providing the minimal realizations of those in two steps, the feedback system and the input transformation system are realized. Then, a detailed discussion is given to the realizability of those two‐dimensional dynamic compensators, i.e., the possibility that the dynamic compensators are proper rational functions with respect to both variables.A counter‐measure for the nonproper case is also proposed. A condition for the obtained three‐dimensional system to be stable is derived. The dimension needed in the realization of those two‐dimensional dynamic compensators, i.e., the dynamical dimension needed in the pole assignment, is calculated. A method for realizing the pole assignment with the lowest dynamical dimension is discussed.
A variable step gain algorithm with fuzzy control
Authors: Katoh Akil , Kubota Hajime 
Published: July 2007

AbstractNumerous methods for a parameter estimation in adaptive signal processing have been proposed. LMS, learning identification method, etc., for example, often are used due to easiness of their hardware construction, but their estimation speed and estimation accuracy vary by contrast depending on the magnitude of the coefficient called step gain. As a method for resolving it, a variable step (VS) algorithm in which the step gain is changed according to the parameter estimation condition has been proposed. However, since the variables in these algorithms that are intended to express the estimation conditions do not fully do so, it remains difficult to control the step gain appropriately.This paper defines anew variables to detect the change of parameters and disturbance and to comprehend the parameter estimating condition, and proposes a variable step algorithm for controlling the step gain by fuzzy controller with these variables as fuzzy input. Furthermore, computer simulation is implemented by applying this method to the learning identification method to show its effectiveness. In particular, with this algorithm we do not need to change the algorithm to deal with variations of the statistical properties of the input signal, and the computational complexity does not depend on the order of the filter; thus it is advantageous for higher‐order identification. Moreover, we have observed that it can cope with observation of noise, rapid change of unknown parameter, and it improves estimation speed by about 15 percent and estimation accuracy by about 20 percent compared with those of existing VS algorithms.
Equivalence of hidden Markov models
Authors: Kabayashi Kingo , Amari Shun‐Ichi , Ito Hisashi 
Published: July 2007

AbstractThe hidden Markov information source (process) is a stochastic process with a finite‐state Markov chain behind it, and the state cannot directly be observed, while only a function of the state is observed as a stream of symbols. This kind of process is very important in both theory and application, but its theoretical structure has not been clarified.This paper gives a sufficient condition for two hidden Markov processes based on different Markov chains to be equivalent as the stochastic process. The condition for that condition to be necessary also is shown. A condition for a hidden Markov process to be equivalent to a Markov chain also is presented.
Evaluation of human exposure to lon‐current using boundary element method
Authors: Yamashita Masaji , Hatori Kozo , Shimizu Koichi , Matsumoto Goro 
Published: July 2007

AbstractWith a view to evaluating the human exposure to ion current generated under a dc power transmission line, the exposure was evaluated by means of a numerical method (1) a new ion current analysis method was developed which can be applied to bodies with complex shapes such as biological bodies. (2) The method is based on the boundary element method, (3) the space charge terms were processed under an assumption of a lumped source of ion current, and (4) comparing the theoretical and experimental data, the error was evaluated. The method was then applied to biological bodies. It was found that the electric field on the surface of the biological body in the ion current field becomes larger than the one obtained in the Laplace field without ion current. This result indicates the importance of the analysis of the ion current field. Further, the variation of the electric field concentration accompanied by changes in the posture of the human body were clarified. The variation of the surface electric field when a body is charged by the ion current was clarified, as well. Hence, this paper provides useful information on the determination of the safety standard and on evaluation of the biological effects of ion current field.
Speech recognition using VQ‐codebooks representing hierarchical spectral dynamics
Authors: Furui Sadaoki 
Published: July 2007

AbstractThis paper proposes recognition methods that use hierarchical spectral dynamic features extracted over multiple time lengths. The effectiveness of these features in phoneme recognition and isolated word recognition is shown. The dynamic features are extracted for time sequences of both cepstral coefficients and logarithmic energy, and are combined with instantaneous cepstral coefficients. Input speech is quantized by word‐or phoneme‐specific codebooks created by clustering a set of vectors consisting of these features for each word or phoneme.Speaker‐independent isolated word recognition experiments are performed using a vocabulary of 100 Japanese words. When VQ distortion is used for word identification, the high recognition accuracy of 96 percent is achieved, and when VQ distortion is used for preprocessing, the number of word candidates for each input utterance is reduced to 1 percent of the vocabulary without increasing the error rate. Phoneme recognition experiments are performed for the /b/, /d/ and /g/ consonants in a large vocabulary of isolated words uttered by one male speaker. Using the proposed recognition method, the high recognition accuracy of 99 percent, which is similar to the accuracies obtained by conventional HMM or neural network approaches, is obtained. This paper also compares multiple codebook and single code‐book methods.
Constructive analysis for infinite‐dimensional nonlinear systems—infinite‐dimensional version of homotopy method
Authors: Makino Mitsunori , Oishi Shin'Ichi 
Published: July 2007

AbstractRelated to the problem such as determination of the operating point for the nonlinear resistor circuit equation, remarkable progress has recently been observed in the global solution method for the finite‐dimensional nonlinear equation, called the homotopy method.This paper attempts to extend the homo‐topy method to the infinite dimensional nonlinear equation (functional equation) such as the equation for the semiconductor devices. First, two streams are pointed out as the theoretical frameworks for the homotopy method for the finite‐dimensional equation, which are: (1) the characterization of the solution structure for the nonlinear equation; and (2) the tracing of the solution trajectory. It is then pointed out that the Fredholm operator equation can be considered as a class of infinite‐dimensional equations, which can characterize the set of solutions as in item (1).The existence theorem for the solution in the finite‐dimensional homotopy method is extended to the class of Fredholm operator equations. Then it is pointed out that the A‐proper operator equation can be considered as a class of infinite‐dimensional equations, for which the computational algorithm for the solution can be described as in item (2). Based on the constructive theorem for the existence of the solution in the finite‐dimensional homotopy method, it is shown that the solution for the particular class of A‐proper operator equations can always be determined by numerical calculation. Finally, an application to the controllability problem is discussed.
A method to minimize output noise in cascade SC filters
Authors: Ma Zhiqiang , Nakayama Kenji , Yamamoto Gaishi 
Published: July 2007

AbstractThe output noise in the cascade switch‐ed‐capacitor (SC) filter depends greatly on the pole‐zero combinations as well as the order of cascading the second‐order circuits. This paper derives the general condition for the combination/order so that the output noise is minimized.First, the noise transmission from each noise source to the output is analyzed for the second‐order circuit. It is shown that the sample‐and‐hold component in the output noise is sufficiently large compared to the continuous‐time component, and the effect of the pole‐zero combination is small.Then, the condition for minimizing the noise transmitted from each second‐order circuit to the output of the SC filter is investigated. The derived condition is that the amplitude response of the transfer function from the filter input to each second‐order circuit should be flat. Translating the condition into the condition for the pole‐zero combination/cascading order, the following condition is derived. For the combination, starting from the pole with higher Q, the closest zero is combined; for the order, the circuits are cascaded so that the frequency at which the amplitude response from the filter input to the second‐order circuit should be distributed.Finally, simulations are executed for 11th‐order low‐pass and high‐pass filters. It is seen that for approximately 40 percent of 36 ways of combination/order with the foregoing condition, the output noise ranges within 20 percent of the minimum value, which indicates the effectiveness of the presented condition.
Relaxation‐based spectrum analysis for nonlinear circuits
Authors: Kawashima Takahiro , Higashiyama Takeshi , Asai Hideki 
Published: July 2007

AbstractIn the spectrum analysis of a nonlinear circuit by the conventional harmonic balance method, a problem occurs when a large number of harmonic components is assumed, that is, the Jacobian matrix of Newton's method for the solution of the determining equation has a large dimension which requires a long computation time and a large memory capacity.From such a viewpoint, this paper proposes an algorithm for the spectrum analysis in the harmonic balance method, where the nonlinear relaxation is applied to the solution of the determining equation. A continuous method is introduced to cope with the convergence problem of the harmonic relaxation method in the strongly nonlinear circuit. Then, to handle the multinode circuit, an iterated spectrum analysis is proposed in which the harmonic balance is applied to each node individually. It is shown that the computation speed in the analysis is improved greatly, while drastically saving the memory capacity in the proposed method, compared to the conventional method based on Newton's method.
Synthesis of an LC filter suitable for LC simulation‐type RC active filters and its application
Authors: Ishibashi Yukio 
Published: July 2007

AbstractOne of the most important measures for the construction of the active RC filter is the element sensitivity. One of the effective means to reduce the element sensitivity is the method to simulate the conventional LC filter with both ends terminated by resistors.This paper considers the realization of the low‐pass filter by LC simulation using GIC or by the node‐voltage simulation. The prototype LC filter is discussed to solve the bias instability problem, which is a problem in the realization.First, an LC filter is proposed which is obtained by adding an inductor in parallel with the input resistor of the conventional doubly terminated LC filter. The method of constructing the filter is discussed. Then a method is presented to simulate the filter using GIC. Finally, the 5th‐order Chebyshev low‐pass filter is constructed and its characteristics are measured. The element sensitivity is analyzed using a computer, and it is verified that the proposed circuit has a low element sensitivity.
A clustering algorithm to minimize recognition error functions
Authors: Ando Akio , Ozeki Kazuhiko 
Published: July 2007

AbstractPattern recognition methods in which multiple templates are prepared for each category and which recognize input patterns using those templates usually partition training patterns into clusters and generate templates as centroids of each cluster. However, most clustering algorithms proposed in the literature aim at minimizing the square error distortion measure when each cluster is represented by its centroid. Therefore the result obtained is not necessarily optimal from the viewpoint of discrimination.This paper describes a new clustering algorithm which is a method of obtaining an optimum solution to a template generation problem. The simulated annealing is used for searching for a cluster partition that minimizes the “degree” of recognition error when all training patterns are recognized by using centroids as templates. This paper also describes a vowel template generation problem in speech recognition as an example of pattern discrimination problems. The new algorithm yielded better experimental results than the LBG algorithm and the LVQ algorithm.
Maximum entropy sampling frequency for stationary gaussian signals
Authors: Sakamoto Hiroyasu 
Published: July 2007

AbstractIn various kinds of digital signal and information systems, there are strong relations between the sampling frequency of signals and the performance or efficiency of the systems. Therefore, many reports have been made on optimization of sampling frequency for various application systems.This paper discusses the problem of determining the optimum sampling frequency for stationary Gaussian signals which does not necessarily satisfy the band‐limited condition of the sampling theorem.First, a brief survey of conventional decision criteria is presented. Based on a common understanding for the amount of information of a sampled datum, a new criterion is proposed that maximizes the entropy rate per one sample. For stationary Gaussian signals, it is expressed in power spectral density functions accompanied by sampling.The criterion compensates for the following defect of the conventional auto‐entropy rate by subtracting the cross‐entropy rate: not only does it properly reflect loss of information due to the occurrence of spectral aliasing error, but also it estimates the spectral error to be information gain.Several properties of the criterion are obtained. As numerical examples, the last part of the paper shows methods for solving the equations for the optimum sampling frequency and their solutions for signals which have nonoscillatory or oscillatory exponential auto‐correlation functions.
An algebraic analysis for bifurcation problems
Authors: Fujisaka Hisato , Sato Chikara 
Published: July 2007

AbstractAn algorithm for computing the codimensions of tangent space for bifurcation equations using the Gröbner basis is presented. When a bifurcation equation with perturbation added becomes equivalent to the original bifurcation problem, the perturbation term belongs to the tangent space; this contains an ideal of a certain equation set on real functions. Therefore, perturbation terms that prevent the equivalence relationship belong to the codimensional space of the tangent space. On the other hand, the residue system of ideals on polynomial rings is found as a set of terms that are not multiples of the highest order of the Gröbner basis.In this paper an algorithm will compute the codimension algebraically by associating the codimensional space of a tangent space with a residue system. Thus, a symbolic manipulation description is adequate for this algorithm. An established algorithm can be similarly applied not only to the case in which a bifurcation equation can be expressed by one variable and one parameter but also to the case in which it is expressed by simultaneous equations of multivariables and one parameter. As an example of computation an equation expressing bifurcation such as Pitch‐fork and Hilltop, etc., was used. The results were verified by illustrating the solution curve when perturbation terms belonging to the codimensional space are added.
A statistical analysis algorithm based on the continuation method
Authors: Inoue Yasuaki 
Published: July 2007

AbstractPerformance of analog IC is affected largely by variations in component characteristics. Therefore, it is necessary to verify at the design stage that the performance of a designed circuit sufficiently satisfies the specifications. Especially important is the verification of variations in dc operating points, which is the foundation of circuit operation. A circuit simulator with statistical analysis function by Monte Carlo method is known as a CAD tool for this verification.In the statistical analysis of dc operating points, reiterative operations are required to obtain repeatedly a solution of a system of nonlinear equations. Thus, the convergence performance of a solution algorithm comes into question. Here, the continuation method to the convergence problem in a statistical analysis of dc operating points of analog ICs is applied. and it is shown that convergence rate and reliability can be greatly improved. First, the computation‐efficient Davidenko approach is shown to be applicable to the statistical analysis of dc operating points of analog ICs. Next, based on this approach, an executive algorithm, the statistical parameter stepping method (SPS method) is proposed. This algorithm improves convergence performance. Moreover, by applying this algorithm to statistical analysis of real analog ICs, its effectiveness is demonstrated.
Design theory of piezoelectric ceramic transformer as an asymmetric filter
Authors: Hirose Seiji , Shimizu Hiroshi 
Published: July 2007

AbstractThe piezoelectric ceramic transformers as a source for a high voltage is used in a high‐energy density state due to its small size so that the energy loss causes increased heat generation and reduction of efficiency. Therefore, it must be treated not only for the voltage step up but as a power transmission system. In the conventional design method for the piezoelectric ceramic transformer, only the voltage ratio was considered important.In this paper, the piezoelectric ceramic transformer is considered as an asymmetric filter with a different capacitance ratio and different termination resistances of the input and output parts. The transmission frequency and the termination condition for a low propagation loss and a high‐voltage ratio were found. As a figure of merit of the piezoelectric ceramic transformer, the voltage ratio x relative bandwidth was proposed. By taking into account this value and the transmission attenuation, an optimum circuit condition of the piezoelectric ceramic transformer was obtained.
Nonrecursive multiple filters on an integer residue ring
Authors: Murakami Hideo , Yamano Gosuke , Koyama Yoichi 
Published: July 2007

AbstractThe finite ring is used for efficient computation of filters. This paper discusses nonrecursive multiple filtering systems on an integer residue ring. The number theoretic transform, which is the Fourier transform on the finite ring, has been used for the design of FIR digital filter on an integer residue ring. A set of filters can be combined to a single filter on a finite ring, using the isomorphism derived from the Chinese remainder theorem. This equivalence is used to compute the outputs of the set of filters efficiently.An efficient algorithm is also presented to find a primitive 2t‐th root of unity which is needed for the construction of the numbers theoretic transform. For filtering multiplicity ranging from two to five, possible choices of moduli are presented. Finally, an example and evaluations of the nonrecursive multiple filter are shown.
Network reliability analysis using dual graph
Authors: Hayashi Masahiro 
Published: July 2007

AbstractThe problem of representing a communication network in a graph and evaluating the overall reliability is NP‐hard. The class of graphs called planar CF graphs is the maximum class whose exact overall reliability is confirmed as being possible to be evaluated by the polynomial order.In this paper, the dual graph to the given graph is constructed, and the overall reliability is evaluated. As a result, the following properties are obtained.
The evaluation of the overall reliability is equivalent to the evaluation of the probability that a circuit exists in its dual graph (dual problem).
The exact value of the dual problem can be evaluated by the reduction method.
There exists a class of graphs which permits the evaluation of the overall reliability by the polynomial order using the method of property (2), and is larger than the Planar CF Graph (we call this extended class Planar Dual CF Graph).