bluuebunny/crossref_metadata_2025_split huggingface dataset:
A consideration for deriving nonbinary irreducible polynomials
Authors: Sugimura Tatsuo , Suetugu Yasunori 
Published: July 2007

AbstractAn irreducible polynomial can be derived in a stochastic way by examining the irreducibility of randomly generated polynomials. On the other hand, a systematic method of derivation for the irreducible polynomial has recently been introduced by presenting a class of irreducible polynomials of particular forms.This paper shows clearly that a higher‐order irreducible polynomial can be derived by applying a suitable variable transformation to the given irreducible polynomial. It is shown also that, when an irreducible polynomial is given where the coefficient is the element of a finite field with odd prime characteristic, an infinite number of higher‐order irreducible polynomials can be derived from that polynomial. A precise algorithm for the derivation is shown.
Synthesis of variable IIR digital filters with complex coefficients
Authors: Murakoshi Nobuo , Nishihara Akinori , Watanabe Eiji 
Published: July 2007

AbstractSometimes it is required to change the filter characteristics of a digital filter in real time during its filtering operation. To meet this requirement, variable cutoff frequency lowpass filters with real coefficients have been reported using only one parameter. Moreover, variable bandpass filters with complex coefficients have been reported where only one parameter was to be changed and where either the upper or lower band‐edge frequency of the passband was fixed. However, in those filters, the frequency response was degraded with the change in characteristics which could not be resolved.This paper proposes the synthesis of a variable IIR digital filter using one parameter and the frequency response is not degraded when the characteristics are changed. In the variable filter proposed here, the cut‐off frequency and the bandwidth may be changed without any restriction. Moreover, a simple circuit realization technique is proposed so that the filter circuit may actually be implemented. In this technique, any type of real coefficient filter circuit may be used as the prototype filter. Finally, the simulation of the synthesis problem is carried out and the validity of the proposed method is confirmed.
Verification of the possibility of separation of sound source direction via a pair of pressure microphones
Authors: Koike Norio , Yanagisawa Takesaburo 
Published: July 2007

AbstractIn this paper, a microphone system with which the directional separation angle can be set variably is proposed with a pair of sound pressure microphones necessary as a minimum to separate and detect the sound source. After the operating principle is described, an experimental verification is carried out. It is confirmed that the separation and detection of the sound sources are possible by the present system for the sound fields constructed by several sound sources with spectral components different from the single source.
Performance evaluation and improvements of ARQ schemes for optical communication
Authors: Uyematsu Tomohiko , Mitsugi Jun , Sakaniwa Kohichi 
Published: July 2007

AbstractThe optical communication system can provide highly reliable and large‐capacity transmission. It is becoming important as the major technology of highspeed digital communication. In the optical communication system, even though it is highly reliable, inevitably the bit error rate is deteriorated with the increase of the transmission rate or the repeater distance. It is anticipated that some methods of error control will be required in the future.This paper discusses the application of the automated repeat request (ARQ) scheme, which is one of the error control methods, to the optical communication. It is noted first that the error that occurs in the optical communication channel is the transition from symbol 1 to “0,” but it can never be the transition from “0” to “ 1.” An ARQ scheme is proposed using the m‐out‐of‐n code which can detect any error in such a channel.A performance evaluation is presented based on the throughput and the information efficiency per photon. It is shown as a result that the SR‐M3BN scheme is the best among various ARQ schemes from the practical viewpoint. It combines selective‐repeat (SR) and go‐back‐N (GBN). Then a new error‐detecting scheme is proposed based on the characteristics of the optical channel, which can reduce the number of repeats of the codeword. It is shown that, by combining the proposed scheme with SR+GBN, a higher throughput can be achieved.
Steady‐state analysis of closed‐loop switching circuit by calculating convolution integral in the steady state
Authors: Suetsugu Tadashi , Mori Shinsaku 
Published: July 2007

AbstractThis paper discusses the convolution integral of the circuit variable and the transfer function in the steady state of a circuit. It is shown that the integral can easily be calculated by the Shooting method when the transfer function to be calculated has a simple form. Using the proposed method of calculation, the steady‐state operation is analyzed for the periodic switching circuit which is controlled by the closed loop, such as the switching converter. A method is proposed that precisely determines the steady‐state operation of the overall circuit, while precisely analyzing the steady‐state operation of the loop circuit.The proposed method differs from the conventional method in that the circuit, including the loop circuit not analyzed but the loop‐control circuit is represented by a transfer function separately from the overall circuit and the steady‐state response is determined by the convolu‐tional integral. Consequently, for closed‐loop switching circuits of various structures, the operation can be determined precisely without enlarging the circuit scale to be analyzed. Another point compared to the past method is that the operation specifications for the circuit can be handled with a better transparency.
Prosodic phrase segmentation based on pitch‐pattern clustering
Authors: Nakai Mitsuru , Shimodaira Hiroshi , Sagayama Shigeki 
Published: July 2007

AbstractThis paper proposes a method to detect the pros‐odic phrase for speaker‐independent continuous speech. The method uses continuous adjustment of a pitch pattern with the learning accent pattern (pitch template). The accent phrase with one accent cue and its corresponding pitch pattern are considered correlated. Distinctive pitch templates are obtained by classifying the pitch patterns corresponding to the accent phrase with the help of clustering.Since pitch patterns of continuous speech are connected to these pitch templates, prosodic phrase segmentation can easily be done by One‐Stage DP matching of the pitch pattern with pitch templates. The method can also be applied to unspecified speakers whose average pitch frequency differs from each other by sliding the pitch template along the vertical axis during the matching.The ATR continuous speech database (10 speakers, 503 sentences) is used for the experiments. For eighc templates, about 65 percent of the automatic prosodic phrase segmentations were correct and the experiment was successful in detecting about 83 percent of the prosodic phrase boundaries.
Error estimation for IDCT finite word‐length calculation
Authors: Mochizuki Takashi 
Published: July 2007

AbstractCalculation error estimation formulas for limited‐accuracy operations of inverse discrete cosine transform (IDCT) are derived, considering the nonlinear property of integer rounding. CCITT Recommendation H.261 specifies a calculation error evaluation method for IDCT schemes under consideration. Considering the nonlinear property of integer rounding in the IDCT final stage, the newly derived formulas can estimate the evaluation results of the H.261's IDCT evaluation method. The validity of the derived formulas is verified by simulation, and it is found that they can estimate the IDCT calculation errors within the 95‐percent statistical confidence intervals and the estimation errors are within 13 percent.
Period‐adding chaos in the Si thyristor
Authors: Yasuda Yoh , Hoh Koichiro 
Published: July 2007

AbstractChaotic behaviors are observed in the anode current of the thyristors where their anodes were excited with an ac source and the constant dc current was supplied to the gate. Three aspects of chaos, i.e., period‐doubling bifurcation, intermittency, and period‐adding chaotic sequence, are observed with different combinations of control parameters.This paper discusses primarily the feature of period‐adding chaos accompanied with intermittency. Also reported is the structure of its bifurcation by using a simple first return map model constructed from the experimental results.
Adaptive sequential testing for educational evaluation
Authors: Kobayashi Osamu 
Published: July 2007

AbstractThis paper proposes the adaptive sequential testing method as one means of proficiency testing. The proficiency test in general has the following problems: 1 the test contains a large number of items which are far from the educational level of the subject and deprives the subject of the motivation for the test; and 2 to secure the accuracy of the test result, the number of items is increased, which burdens the subject. To solve these problems, a system is considered in which test items for which correct/incorrect decision can be made immediately are pooled and the items are selected by a computer to be presented to the subject.As the method of testing, the adaptive sequential testing is extended to the case of multiple hypothesis and the adaptive selection is proposed for the selection of the test items. In the proposed testing system, only the correct answer ratio for each educational level is attached to the pooled test items. By a trial simulation, the number of posed problems is halved and the system is verified to be a practical testing method with less burden to the subject.
Asynchronous simultaneous oscillations in negative resistance oscillatory circuit containing a periodically operating analog switch
Authors: Matsuki Michitaka , Mori Shinsaku 
Published: July 2007

AbstractIt is known that asynchronous simultaneous oscillations cannot exist in the oscillatory circuits of two degrees of freedom with a negative resistance if the current and voltage characteristics are of a third‐order polynomial and they take place as a hard oscillation if the characteristics are of a fifth‐order function [1, 2]. The authors have reported that, even in the circuit made of a third‐order negative resistance and a resonator for which no resonance occurs, a resonance occurs in a certain frequency region of switching if an analog switch is inserted between the negative resistance and the resonator and is periodically operated. It is reported that a hard oscillation phenomenon occurs in a portion of this region. It is predicted than an asynchronous simultaneous oscillation becomes possible by this hard oscillation characteristic if there are two resonators.This paper attempts to carry out a theoretical study and an experimental confirmation for the possibility of asynchronous simultaneous oscillations by the periodic operation of a switch even if the nonlinear resistance is expressed in a third‐order function.
A computational model of auditory segregation of two frequency components—evaluation and integration of multiple cues
Authors: Kashino Kunio , Tanaka Hidehiko 
Published: July 2007

AbstractAs part of the basic research on perceptual sound source separation, a quantitative model is presented which gives a probability of auditory segregation of two frequency components. The model consists of independent evaluation of multiple spectral features and integration of those derived values.First, psychoacoustic experiments which measure the probability of auditory segregation of two frequency components are described and evaluation functions of spectral features to approximate those experimental results are introduced. Then a method for integrating the spectral features is discussed and correlations between the model output and the results of the psychoacoustic experiments are measured.
Robust LQG control system under parameter uncertainty
Authors: Maki Midori , Hagino Kojiro 
Published: July 2007

AbstractThis paper presents a method of designing a robust linear quadratic Gaussian (LQG) controller for systems with unknown parameters when an accurate model is not available. The proposed robust LQG control scheme results in the prevention of the system performance deterioration caused by the parameter uncertainty without estimating unknown parameters explicitly.First, an approximate model is introduced to describe the uncertain parts of the plant and a target model which the controlled system should track is constructed based on the known nominal system and the approximate signal generated by this approximate model.Next, this tracking problem is changed to the LQG control one for an augmented system. This target trajectory is determined automatically in control operation for the augmented system. Further, both the controller and filter gain are determined as a solution of a deterministic suboptimal control problem.
Consideration of subjective evaluation method for quality of image coding
Authors: Narita Nagato 
Published: July 2007

AbstractSubjective evaluations of coded images are often made by using the double‐stimulus continuous‐quality‐scale method of the ITU‐R Recommendation (old CCIR Wireless Communications Group). In this paper, the reliability of the double‐stimulus continuous‐quality‐scale method is investigated. Using this method, subjective evaluations of coded video sequences are made and the consistency of the test scores of the reference sequences is analyzed. Although it is desirable to have consistent reference test scores, results show that the test scores vary due to the influence of the quality of the video sequences being tested. As a result, dealing with image evaluation scores obtained from the double‐stimulus continuous‐quality‐scale method (with scores made on an absolute scale) may be ill advised.Next, the reliability of data obtained from processing the differences between scores (relative scale scores) of reference and test images obtained from the double‐stimulus continuous‐quality‐scale method is investigated. Results show that compared to this method, scores obtained from the modified EBU method (modified in the sense that the video presentation method differs from the standard EBU method) have higher reliability when impairments are small and are suitable for the subjective evaluation of coded images.
Scattering center estimation of a conductive sphere using a superresolution technique
Authors: Yamada Hiroyoshi , Ogawa Yasutaka , Itoh Kiyohiko 
Published: July 2007

AbstractUnderstanding electromagnetic scattering phenomena at high frequencies is important in specifying the location of the local scattered wave (scattering center). This procedure also is available for the practical radar target recognition. Detection of the scattering center also is possible by means of the Fourier transform in the frequency data measured by a network analyzer. However, since its resolution is limited by the measured frequency bandwidth, practical applications may often be difficult.In this paper, the use of the MUSIC algorithm which has a higher resolution than the Fourier transform is proposed for the time‐domain estimation method of the electromagnetic scattering. As an example, the detection of the scattering center in the backscattering measurement of a conductive sphere is discussed. It is pointed out that the algorithm can be applied without significant modifications. Most of the superresolution methods require many snapshots. It is found by computer simulation that the noise suppression preprocessing by time‐domain gating is effective for reduction of the snapshots. The setting of the number of incident signals (scattering center) of the MUSIC algorithm in the time‐gated data is discussed. Further, by experiments, these investigations were verified and the high‐resolution nature of the present method is proven.
A generalized orthonormal discriminant vector method for pattern recognition
Authors: Hamamoto Yoshihiko , Tomita Shingo 
Published: July 2007

AbstractDiscriminant analysis on one of the well‐known feature extraction methods. Unfortunately, discriminant analysis has a serious shortcoming in that the maximum number of features is limited by the number of pattern classes. To solve the forementioned shortcoming, Okada and Tomita proposed the orthonormal discriminant vector (ODV) method based on the Fisher criterion. However, no feature is provided by the ODV method when the mean vectors are the same.First, this paper proposes a new ODV method based on a generalized Fisher criterion which takes into consideration the difference of covariance matrices. Second, a theoretical comparison is made between the proposed method and the other feature extraction methods. Finally, experiments are conducted to show the usefulness of the proposed method.
Results of observational studies of spatial workspace collaboration
Authors: Kuzuoka Hideaki , Shoji Hiroko 
Published: July 2007

AbstractMost studies on groupware have focused on desktop‐type collaboration in two‐dimensional (2‐D) space. However, to apply groupware to manufacturing or more general and free communication, groupware must be developed that supports expressions of 3‐D shapes and motions. Collaboration in the 3‐D environment will be called “spatial workspace collaboration” to distinguish it from the conventional type of collaboration.To evaluate and understand spatial workspace collaboration, the point of focus, number of words, and verbal expressions were examined. Based on these analyses, the following requirements on groupware are deduced to support spatial workspace collaboration: realtime bi‐directional video communication; availability of nonverbal expressions; positional changeability of point of focus; ability to share points of focus; positional changeability of display; and confirmation ability.
Data maintainability of a secondary storage medium with backup copies: An evaluation model and its application
Authors: Fukumoto Satoshi , Yasui Kazumi , Nakagawa Toshio 
Published: July 2007

AbstractA backup copy of a secondary storage medium is among the most practical resources in fault tolerant techniques. Data maintainability of two backup configuration types are discussed here. One is a single backup type comprising a current data medium and a backup data medium; the other is a redundant backup type comprising a current data medium and backup data two media. Taking account of state transitions of each backup configuration and the frequency of failures, a new stochastic model is proposed using a discrete‐time Markov chain to evaluate quantitatively the data maintainability of two types. The model is concretely applied to the backup configurations of floppy disks. By estimating failure probabilities of the media of floppy disks from a small‐scale questionnaire, we obtain several significant properties of two types of backup configuration for media.
Disturbances of decca waves near a huge bridge
Authors: Sato Naoto , Miyazaki Yasumitsu , Yamashita Michiko , Takenaka Yasuo 
Published: July 2007

AbstractA hyperbolic navigation system using a radio wave in the 100‐kHz band is installed in the ocean surrounding Japan. This system is used widely by the fishing industry because the reproducibility of the measured location is high. Recently, near the land, several huge structures such as the Seto Bridge have been erected on the water which causes significant error in determining the location of a ship.This paper studies the disturbances of Decca waves of the Kita‐Kyushu Decca chain due to the Minami‐Bisan Seo‐Ohashi Bridge. It was found that, with respect to the disturbance of Decca waves, the two main towers of the suspension bridge could be considered as vertical electric dipoles. In the measurement of the electrical field strength at four frequencies of the Decca station, the standing wave of the electrical field strength appeared more conspicuously with a higher frequency at the locations away from the bridge by more than 0.18 wavelength except near the bridge on the west side. It is assumed that the secondary waves from two main towers considered as vertical electric dipoles are superposed on the primary wave. Then the numerical results are carried out from the theoretical equation of the received electric field, and the measured results are explained. Also, it is found that the static capacitance of the vertical electric dipoles is 0.1 to 0.2 μF. Hence, it was possible to establish a macroscopic model of the bridge for which the main towers are considered as vertical electric dipoles.
A general method for generating odd‐shift orthogonal sequences
Authors: Ohue Kenji 
Published: July 2007

AbstractIn general, it is difficult to derive a finite sequence which minimizes the sidelobe of the autocorrelation function. However, it is shown that there exist the evenshift orthogonal sequences, i.e., the finite sequences for which the even‐shift autocorrelation function takes the zero value. the generation method also is shown. On the other hand, there has not been known the general method for generating the odd‐shift orthogonal sequences, for which the odd‐shift autocorrelation takes the zero value. Neither have the properties of such sequences been analyzed.This paper presents the general method for deriving the odd‐shift orthogonal sequences, using the complex function as the generating function and constructing the numerical sequence from the Fourier expansion coefficients. First, the one‐ and two‐dimensional odd‐shift orthogonal complex sequences and odd‐shift orthogonal real sequences are defined from their autocorrelation functions. Then, it is shown that those numerical sequences are odd‐shift orthogonal sequences if they are skew‐symmetrical sequences. Finally, the properties of the generating functions that derive those odd‐shift orthogonal sequences are shown, together with the generation algorithm.
FIR and IIR SC interpolation filters using parallel cyclic‐type circuit for high frequency
Authors: Hashimoto Mitsuru , Hirata Yoshinori , Takahashi Nobuaki , Takebe Tsuyoshi 
Published: July 2007

AbstractHigh‐frequency responses of switched‐capacitor filters deteriorated mostly as a result of the finite gain bandwidth product of an operational amplifier. the authors previously proposed a type of FIR and IIR switched‐capacitor filter using a parallel cyclic‐type circuit in order to improve high‐frequency performance. In the parallel cyclic‐type circuit, an operational amplifier is not used as a delay element. Instead, both delay and weighting operations are implemented with switches and a coefficient capacitor simultaneously. Only one operational amplifier is used for a summing operation. Consequently, the maximum operational frequency of the filter is extended up to the unity gain frequency of the operational amplifier.This paper proposes a new type of FIR and IIR switched‐capacitor interpolation filter that can be operated in a high‐frequency region by using the parallel cyclic‐type circuit. Effects of both the finite gain bandwidth of the operational amplifier and parasitic capacitances on filter performance are analyzed by applying the analysis method of periodically time‐varying digital filter. These effects are found to be very few in number below the unity gain frequency of the operational amplifier. Third‐order FIR and biquadratic IIR interpolation filters are constructed with discrete components and verified to have good frequency performance that coincides with the analyzed one.