bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThe 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

AbstractSounds 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.
Physical mechanisms of chaos in a third‐order autonomous circuit family with a diode
Authors: Inaba Naohiko , Saito Toshimichi 
Published: July 2007

AbstractThe physical mechanism of chaos arising in a third‐order autonomous circuit family containing a diode is discussed in relation to the variation of the oscillation frequency of the circuit. The family to be studied is negative‐resistance LC oscillators containing a nonlinear inductance made of two coils and one diode. When the ratio of the two coils is large, the oscillation frequency of the circuit varies significantly by the on‐off operation of the diode and the resulting “folding” causes chaos.If the diode is considered a switch, the circuit equation is represented by a form in which the linear ordinary differential equations with significantly different oscillation frequencies are switched to each other. The meaning of the folding becomes clear even in the equation. By means of this and the exact one‐dimensional Poincaré mapping, the generation of chaos is explained clearly and rigorously.
Determination of the number of sinusoidal signals in AR spectral estimation
Authors: Tsuji Hiroyuki , Ohmori Hiromitsu , Sano Akira 
Published: July 2007

AbstractIn carrying out the AR spectral estimation of observed signals consisting of the sum of sinusoidal signal and white noise, since at low SNR many more false peaks occur than the number of sinusoids, a method which uses the eigenvalue decomposition of the correlation matrix to adopt only as many eigenvalues as the number of sinusoids, discarding the rest, is very effective. However, if the number of signals is unknown, how the discarding of eigenvalues should be determined becomes an important problem.In this paper, to select an appropriate number of eigenvalues of the correlation matrix of the observed data, a multiple number of adjustable parameters is introduced to square the prediction error and, by determining them optimally, determine the number of eigenvalues.Two new methods are proposed. The first method decides the truncation number of eigenvalues so that the Bayes information criterion with a priori distribution is minimized. The decision criterion is derived and its properties are investigated. The second method determines the number of sinusoids by computing adjustable parameters so that the AR spectrum of a given rank is the closest to the true AR model representing the sinusoidal signal model approximately, that is, the MSE criterion is minimum.Finally, the effectiveness of the authors' methods are investigated through numerical examples.
A new FIR switched‐capacitor circuit for high‐frequencies with low‐power consumption (parallel cyclic‐type circuit)
Authors: Hirata Yoshinori , Takahashi Nobuaki , Kato Kyoko , Kikui Toshiharu , Takebe Tsuyoshi 
Published: July 2007

AbstractThe high‐frequency performance of switched‐capacitor filters is bounded mainly by the finite gain bandwidth product of operational amplifiers. In this paper, the effects of finite gain bandwidth product of operational amplifiers on the performance of FIR (transversal) filters using such amplifiers as delay elements (canonical circuit) is analyzed. Next, a new low‐power consumption FIR switched‐capacitor circuit for high frequencies, which we call a parallel cyclic‐type circuit (PCTC), is proposed. The proposed circuit does not use operational amplifiers as delay elements. Instead, switches and capacitors are used for both the delaying and the weighting operations.We present a basic circuit using subblocks, a circuit with reduced number of capacitors, and a modified circuit having plural operational amplifiers for higher‐frequency use. We then show the design of a fourthorder FIR filter employing PCTC. Under the condition that sampling frequency is one‐half of unity gain frequency of operational amplifier, computer simulations of fourth‐order transversal switched‐capacitor filters with canonical circuit and that with parallel cyclic‐type circuit are performed and the experimental results of these circuits using discrete components are also given. Both demonstrate that the parallel cyclic‐type circuit has significantly better performance than the canonical circuit.
Development of a basic software which serves redundant input devices
Authors: Koyama Satoshi 
Published: July 2007

AbstractSeveral input/output (I/O) devices should be prepared for a computer user, and its is important that the user be able to choose a suitable one. The author developed an additional basic software which serves redundant input devices: keyboard, mouse, touch‐screen, and other external input devices. The user may operate any of these devices as desired. This software will establish computer‐accessibility for some types of handicapped individuals and will be useful in developing user‐friendly programs. It should also be mentioned that this software is useful in constructing computer‐assisted learning systems which accept concurrent operation.
Student model and its recognition by hypothesis‐based reasoning in ITS
Authors: Matsuda Noboru , Okamoto Toshio 
Published: July 2007

AbstractThis paper describes a framework to infer a student's misconception from observed errors during problem‐solving processes. A human teacher can generate hypotheses about reasons for an error by observing a student's problem‐solving process. The teacher is also able to identify a student's misconception during the process of verifying these hypotheses. Furthermore, by using these hypotheses, the teacher can generate new tasks to evaluate the student's understanding level. In this way, appropriate instructions based on the student's knowledge structure can be provided.To accomplish such a behavior within an intelligent tutoring system (ITS), the authors have defined a domain model and applied hypothesis‐based reasoning to diagnose the student model. When the system finds an error in a student's problem‐solving process, it attempts to generate hypotheses which explain that error in terms of the domain model.
A lower bound analysis for bit error rate of trellis‐coded QPSK modulation in impulsive noise environment
Authors: Nakano Etsuhiro , Iwanami Yasunori , Ikeda Tetsuo 
Published: July 2007

AbstractThe efficiency of trellis‐coded modulation (TCM) schemes against Gaussian noise has been well known. However, its performance for impulse noises, which degrade the quality of urban radios, wire communications, and so on, remains unknown.This paper pays special attention to a trellis‐coded QPSK modulation scheme, for example, and clarifies the analysis method of lower bounds of bit error rates. Also, computer simulations were made to verify the analytical results. As a result, the efficiency of the TCM scheme against the impulse noise has been clarified.
Synthesis of flow networks minimizing the sum of edge capacities
Authors: Kishimoto Wataru , Takeuchi Masashi , Kishi Genya 
Published: July 2007

AbstractSeveral methods to construct a flow network minimizing the sum of edge capacities which have the given terminal capacity matrix are already known. However, there exist some networks that cannot be constructed by known methods.This paper considers the case where the given terminal capacity matrix is an elementary terminal capacity matrix. A method is proposed to construct a flow network with the minimum sum of edge capacities, which has the given matrix as the terminal capacity matrix. Using this method of construction, any flow network with the minimum sum of edge capacities that has the given elementary terminal capacity matrix can be constructed.
Multichannel IIR filter banks composed of all‐pass filters as construction elements
Authors: Wada Shigeo , Takahashi Shin‐Ichi 
Published: July 2007

AbstractFilter banks are being used in many areas, e.g., voice processing in communication systems; and active research has been on‐going in this field in recent years.This paper describes a method of realizing multichannel IIR filter banks which could divide the frequency range into an arbitrary number of uniform bands. In this method, filter banks are formed by shifting the low‐pass characteristics with the help of variable transformation with respect to ω and a π/2 phase shifting with the help of a Hilbert transformer. Hence, this design procedure becomes similar to the design of linear‐phase all‐pass filters.This IIR filter including the Hilbert transformer can be implemented with the help of an all‐pass filter, and thus low coefficient sensitivity property can be realized. Moreover, the transition band is narrower compared to the FIR structure. Other than the forementioned merits, the design is comparatively simple; and all the coefficients can be obtained in an analytical way using Fourier series expansion.
A phase approximation method and stability conditions of all‐pole systems in terms of 2‐D line spectrum pair
Authors: Kato Takayuki , Hamada Nozomu 
Published: July 2007

AbstractThis paper discusses the stability of a two‐dimensional (2‐D) all‐pole system, especially its relation to the phase characteristic. The discussion starts with Ekstrom's stability condition for the asymmetrical half‐plane model, which is the most general as the 2‐D infinite impulse response (IIR) system. The stability theorem known for the phase characteristic of the 1‐D all‐pole system is extended and applied to the 2‐D case. The 2‐D line spectrum pair is introduced as the intersection of the phase characteristic of the 2‐D all‐pole system and a particular set of planes. The stability theorem for the all‐pole system is derived as the condition for such a system. Then, based on the stability theorem for the 2‐D all‐pole system, an approximation method for the phase by the all‐pole system which ensures the stability is proposed.It is shown that the proposed phase approximation method corresponds to a particular case of the signal restoration using only the phase data given by Oppen‐heim et al. As an improvement of the proposed phase approximation method, the evaluation function by Oppen‐heim based on the error of the equation is replaced by the evaluation function which is the phase error itself. The error minimization method is proposed.Finally, as an application example, the phase compensation problem by the all‐pass system is considered, and the usefulness of the proposed method is demonstrated.
Numerical analysis of bifurcations in Duffing's equation with hysteretic functions
Authors: Matsuo Tetsuji , Kishima Akira 
Published: July 2007

AbstractThis paper analyzes numerically the bifurcation phenomenon in Duffing's equation containing a hysteretic function and reports on the result of investigation of the effect of the hysteretic characteristics on the bifurcation.First, a large number of steady hysteresis loops is derived by numerically integrating the state equation of the system with various initial conditions, and the sets of the steady periodic solutions are observed. Then, using the method already proposed by the authors, the bifurcation of the steady solution is analyzed while varying the parameters of the system. The effects of the hysteretic loss and the ohmic loss on the bifurcation of the system are compared, and the difference is discussed. An example of the generation of chaos caused by increasing the hysteretic loss is shown.
Performance of robust detector for very heavy‐tailed noise distribution
Authors: Sato Tatsuo , Yumoto Hideki 
Published: July 2007

AbstractIn previous studies of the robust detector, it is assumed that the noise density function of the nominal function is a “strongly unimodal” density function, with a lighter‐tail than the exponential function. On the other hand, the actually observed noise density function often has a heavier‐tailed density function (more strictly, probability density function) than the exponential function; and the traditional method cannot be applied.From such a viewpoint, this paper considers the heavier‐tailed density function than the exponential function and introduces the concept of “nonstrongly unimodal” property. The concept is defined; and using the corresponding nominal density function, the robust detector is designed based on the actually observed underwater acoustic data. The performance is examined.In terms of the performance, the robust detector designed by the authors is compared with the linear and sign detectors. It is shown as a result that the robust detector designed by the authors is much better and useful.
Nonuniform perfect‐reconstruction systems for quadrature mirror filter banks
Authors: Kurosawa Kaoru , Fujita Yoichi 
Published: July 2007

AbstractBy decreasing the decimation ratio to one less than the number of channels, a perfect‐reconstruction quadrature mirror filter (QMF) system can be constructed with the following innovative features: (1) the band division, which in the past has been uniform, can be made nonuniform; (2) the equivalent delay, which has usually been as large as the order of the dividing filter, can now be reduced to a size equal to the decimation ratio minus 1; (3) the number of channels, which has been restricted to a power of 2, can now be arbitrary. In addition, the traditional method employs spectral decomposition, while the proposed method employs Euclidean division. Euclidean structure (the realization of Euclidean division on a network) and lattice structure are considered as methods of constructing a filter that does not produce an aliasing distortion for the finite word length.
Design of a ternary coding scheme and of single‐error‐correcting ternary hamming codes
Authors: Muranaka Noriaki , Imanishi Shigeru 
Published: July 2007

AbstractThe structural units in multivalued (MV) information processing systems, such as the MV arithmetic unit which executes arithmetic operations, the MV memory unit in which MV information is stored, and the MV sequential unit which contains counters, have been widely studied and reported on. There have been very few studies, however, on the encoder and decoder necessary to transmit and store the data in an MV system. In this paper, we present the most primitive ternary codes used in MV error detecting/correcting codes with parallel input signals. Ternary codes are useful for improving the reliability of an MV information processing system.First, examples of ternary three‐digit codes coded in ternary coded decimal (TCD) are shown and their characteristics described. Then we describe single‐error correcting ternary Hamming code I, code I′, code I″, and code II, from extensions of the binary Hamming codes to ternary. As a result, increases in the maximum code length may be realized. Finally, we present the design of an encoder and decoder with a single‐error correcting Hamming code II in a parallel input system and discuss the implementation of these circuits.
High‐rate, power‐efficient coding for optical communication: Design and performance evaluation
Authors: Uyematsu Tomohiko , Yagi Hideaki , Sakaniwa Kohichi 
Published: July 2007

AbstractIn the direct detection optical communication system which detects the optical pulse by counting the photons, it is known that the information transmitted by each photon has an important role in the performance evaluation of the error‐correcting code, in addition to the code rate and the decoding error rate. Especially, for the code which can achieve arbitrarily small error rate by increasing the code length, the performance of the code can be evaluated based on the code rate and the information efficiency. However, these two evaluation measures are in a trade‐off relation; and there is a limit if one attempts to improve both.From such a viewpoint, this paper determines the bounds for the code rate and the information efficiency and determines the limit of performance when the ideal error‐correcting code is applied to the direct detection optical communication. Then, as a code which can arbitrarily achieve a small error rate, a new code based on the iterated code is proposed. It is shown that if the code rate is less than 0.75, the proposed code can achieve a better information efficiency than the conventional code with the same code rate.
Effect of stereo television presentation on “mental rotation”
Authors: Nagamine Kazuhito , Nakayama Minoru , Shimizu Yasutaka 
Published: July 2007

AbstractThe effect of stereo television presentation on “mental rotation” was examined. When the orientations of two identical or mirror figures are changed and then displayed, mental rotation is the phenomenon that the time taken to decide this difference is proportional to the angular difference between the orientations of the two figures. First, the reaction times when the presentations were in two and three dimensions were compared, and the effectiveness of the three‐dimensional presentation was studied. The result was that, even when displayed in three dimensions, a mental rotation similar to that of the two‐dimensional case was verified and the reaction time was significantly shortened. The result of studying the internal processes showed that three‐dimensional presentation was effective from the standpoint of the transformation to the internal representation. The subjects were divided into two groups based on their reaction times. When the effectiveness of the three‐dimensional presentation was studied, three‐dimensional presentation was particularly effective for the group with the short reaction times. Furthermore, when a part of the presentation figures were marked with color, the speed for rotating the representation became significantly faster regardless of the presentation dimension. By studying the subjects, we found colored marking was effective for subjects with long reaction times.
Improvement of analysis accuracy of high pitch speech utilizing residual of linear prediction analysis
Authors: Fukabayashi Takeshi 
Published: July 2007

AbstractThis paper proposes a method to improve the accuracy of analysis in the traditional linear prediction analysis by utilizing the information contained in the residual due to the analysis error. In the proposed method, the linear analysis is applied first to the speech data and the residual is determined. At every interval almost equal to one pitch period, “0” sequences composed of more than one “0” are inserted into appropriate positions of the residual and the sequence is prolonged to the backward direction. The linear prediction analysis is applied to the resulting sequence.When the residual of the sequence with more inserted “0′s” than the order of the residual analysis is processed, the autocorrelation coefficient up to the delay needed for the analysis is equal to the sum of the independently determined autocorrelation coefficients between “0” sequences. Consequently, the result is almost equal to the analysis of the residual for almost one pitch period using the average autocorrelation function. This reduces the effect of the pitch period of the residual.Next, the impulse response sequence of the all‐pole filter constructed from the linear prediction coefficients of the residual is determined. The spectrum of the forementioned impulse response sequence is an approximation of the spectral envelope of the residual. The foregoing impulse response sequence is passed through the all‐pole filter determined previously from the linear prediction coefficients of the speech. The output, i.e., the synthesized waveform, is analyzed. It is shown by the analysis experiment of the synthesized speech that the accuracy of the analysis can be improved by this method.
Generalized representation of integers
Authors: Chujoh Takeshi , Hirasawa Shigeichi , Inazumi Hiroshige , Nishijima Toshihisa 
Published: July 2007

AbstractBy the problem, called a representation of the integers, is meant the encoding of the positive integers without a known upper bound, for which unique decoding can be provided. From the viewpoint of information theory, this problem has been discussed theoretically in its relation to the universality, asymptotic optimality, and computation theory. The result in those approaches has been applied to the data compression scheme for the type of data referring to the past as well as the URR and other floating‐pointnumber representations with variable exponential length.This paper discusses representation of the integers problem from the viewpoint of the codeword‐length function, which is the function to represent the length of the codeword. As a result, a general construction method is presented which has the desirable property and can uniquely encode all representations.Several methods are given from this approach, which can construct not only the traditional representations of the integers but also the first representations of the integers which has not been considered. It is noted first that two construction methods of codeword length, which are independent of the encoding, are considered. One is based on the combination of the codeword‐length functions, and the other is based on the codeword‐length distribution. More precisely, it is shown that not only are the traditional representations derived, but also the representations that have not been considered in the past. Using detailed examples, it is shown that the computational complexity of the encoding and decoding depends on the codeword‐length function.
FITS: A generic framework for intelligent tutoring systems
Authors: Ikeda Mitsuru , Mizoguchi Riichiro 
Published: July 2007

AbstractThis paper summarizes the research result up to the present concerning the generic framework FITS for ITS. FITS is composed of six building blocks, which are teaching‐material‐independent, and the scheduler to realize the flexible teaching process. By developing the generic framework reflecting the essential task structure of ITS, the manpower needed in developing ITS can be reduced.This paper describes the design philosophy of the generic framework FITS and the mechanisms of the building blocks using the case of the teaching of geography as an example.