bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spoken word recognition of independent speakers using local‐peak‐weighted average dictionary
Authors: Matsumoto Hiroshi , Nakagawa Masao , Yoneyama Masahide 
Published: July 2007

AbstractA method has been proposed in the spoken word recognition, which utilizes the frequency‐time pattern inherent to the word. However, in the application of the method for speech by unspecified speakers, normalization is required, in contrast to the case of specified speakers, since the formant in the pattern may be shifted along the frequency‐axis due to the individual difference of harmonization organs of the speakers. The method including the formant normalization or nonlinear conversion of the frequency‐axis contains a larger computational complexity, and is not suited to a large vocabulary of words. From such a viewpoint, this paper proposes a method, in which a common weighted average dictionary is constructed by superposing the binary local‐peak patterns of speakers, absorbing their individual differences into a dictionary. The individual differences of speakers are also overcome by matching with the dictionary the binary pattern with an allowable width along the frequency‐axis centered around the local peak of the input speech. The weighted average dictionary is only a pattern set representing the frequency of the local peaks inherent in the word, and the storage of data requires less memory capacity. Since the input pattern is matched based on the binary pattern set, the computational complexity is also reduced. With 110 words of 0A command as the sample speech, both male and female speech is used as the inputs. When the input speakers are restricted, a recognition rate of 97 percent was obtained for restricted speakers and nearly 92 percent was obtained for unrestricted speakers.
Estimation of poles and zeros of voiced speech using group delay characteristics derived from spectral envelopes
Authors: Mikami Naoki , Ohba Ryoji 
Published: July 2007

AbstractA11‐pole models have been used in speech signal analysis to represent speech‐producing systems [1]. This paper introduces a new method for analysis of the group delay characteristics derived from spectral envelopes. The method derives the complex cepstrum from the spectral envelope connecting peaks of fine structure of the power spectrum.The effectiveness of the method is shown by application to synthesized and actual nasals.
Wave digital filters based on extracting two‐wire lines
Authors: Suzuki Masakiyo , Suzuki Masatoshi , Miki Nobuhiro , Nagai Nobuo 
Published: July 2007

AbstractIt is well known that wave digital filters (WDF's) imitating the behavior of doubly terminated reactance circuits have low coefficient sensitivity properties. Based on the Darlington synthesis procedure, a cascade synthesis of WDF's realizing arbitrary transfer functions has been shown. They are constituted with cascading basic WDF sections corresponding to basic reactance sections. The cascade synthesis procedure, however, is rather complicated in that transmission zeros have to be found by calculating the roots of an algebraic equation.
Multipurpose equipment practice for communication office terminals and its cooling characteristics
Authors: Yasukawa Hiroshi 
Published: July 2007

AbstractIn recent years physical design has played a major role in the development of digital and LST techniques. This paper describes the profiles and several requirements of communication office terminals with consideration of physical design technology and presents an evaluation method for equipment practice. New equipment practice with multipurpose both‐side ducts inside a. cabinet, used for exhausting air and/or cable wiring, is proposed. The relationship between physical structure and natural air‐cooling characteristics is empirically examined and it is shown that good results are obtainable relative to the packaging properties of the proposed equipment practice compared with conventional types.
Improvement of multiple access capability in m‐ary‐FSK/direct‐sequence SSMA
Authors: Yamauchi Yukiji , Sato Masashi , Morinaga Norihiko , Namekawa Toshihiko 
Published: July 2007

AbstractIn the conventional SSMA (Spread Spectrum Multiple Access) system, the number of co‐channel users is unexpectedly small and the increase in the number of co‐channel users is one of the subjects of SSMA. Introduction of error correcting codes, improvement on primary modulation, etc., have previously been proposed. Especially in direct‐sequence SSMA, primary modulation using modified M‐ary FSK has been reported to provide a remarkable improvement. A primary modulation scheme using modified M‐ary FSK, named “unpacked MFSK/DS,” is presented here for improving the multiple access capability on direct‐sequence SSMA by flattening the power spectrum of transmitted SS signals. It is shown that the number of co‐channel users in SSMA can be increased to twice as many as that of the conventional MFSK/DS systems only by modifying the frequency allocation of MFSK symbols and without modifying the conventional MFSK transmitter/receiver configuration.
A method analyzing the bifurcation of almost‐periodic oscillation and generation of chaos in a parametric excitation circuit
Authors: Inoue Masakazu 
Published: July 2007

AbstractThis paper discusses the bifurcation of the almost periodic oscillation and the generation of chaos in a parametric excitation circuit. The system to be considered is described by a third‐order nonautonomous differential equation.Here, the original equation is converted into an autonomous system by using the averaging method. Then the behavior of the solution curves is examined by the phaseplane analysis. The bifurcation of the almost‐periodic oscillation and the generation of chaos under varying amplitude of the external excitation are discussed in detail. The feature of the method of analysis of the autonomous system used in this paper is that the solution trajectory can be obtained easily. Since the analysis is a kind of approximate method, the result is compared with that of the mapping method which produces an accurate solution. It was verified that the limit cycle obtained in the autonomous system corresponds to the invariant closed curve of the mapping method, and that the bifurcation of the limit cycle leading to the almost‐periodic oscillation and its transition to chaos also agree with the result of numerical computation obtained by the mapping method.
A traffic control method by adaptive reservation scheme using subchannel on bus‐type local networks for integrated voice and data
Authors: Tokinaga Shozo 
Published: July 2007

AbstractThis paper deals with an adaptive traffic control method which utilizes a reservation scheme using the subchannel on bus‐type local area networks for integrated voice and data traffic. For conflict‐free transmission over the main channel, each terminal is given a binary address and sends its own address bits serially on the subchannel for reservation. For realtime processing the voice terminals usually have higher addresses than that of data terminals. If the waiting time of data packet grows more than a threshold, the data terminal obtains a higher address temporarily while maintaining the discard rate of voice packets below on allowable level. The traffic characteristic is compared with other multiaccess protocols; as a result its data transmission performance and the number of accommodated voice terminals are shown to be excellent. The hardware realizability of the system is also studied through fabrication of a trial system.
Strip line‐type microwave modulator using photoconductivity
Authors: Ogusu Kazuhiko 
Published: July 2007

AbstractWhen the strip line containing a semiconductor material is illuminated by light with an energy larger than the band gap, the resistivity of the semiconductor changes and the control of the microwave propagation in the line can be realized. For high‐speed control it is necessary to use the semiconductor with short lifetime and to increase the intensity of illuminating light. In this paper, a fundamental study has been performed for the microwave modulator using photoconductivity. Strip lines suitable for this modulator are a coplanar waveguide and a slot line. This paper investigates the coplanar waveguide. An optimum structure is found that provides the strongest microwave attenuation for a given light intensity. The dependence on the frequency of the attenuation constant is also found. The analysis is based on the spectral domain method. To confirm the usefulness of the modulator proposed here, the modulator has been made of Si and tested at 10 GHz. It is found that the modulation up to 100 kHz is possible even with a light source such as a lightemitting diode.
Injection locking of a double‐mode oscillator with fundamental and third harmonic resonators
Authors: Umeda Hiroyuki , Hayashi Hisao , Kitagawa Nobuo , Shiraga Yoshiaki 
Published: July 2007

AbstractThe injection locking of the solid‐state oscillator has been studied from the viewpoint of various applications such as modulation, detection, regeneration and amplification of signal in communication systems. The injection locking oscillation with harmonics exhibits various peculiar phenomena which are not observed in the single‐mode oscillator with single resonant circuit. This paper discusses the double‐mode oscillator composed of fundamental and third harmonic oscillations. The major results are as follows: (1) The effective increase of the Q value for the fundamental frequency due to the presence of the third harmonic is evaluated in terms of the effective external Q; (2) It is shown that the locking equation for the phase in the simultaneous oscillation of fundamental and third harmonic frequencies, is of the same expression as that of the basic equation second‐order loop (with imperfect integrator) in the phase‐locked loop (PLL). The equivalent loop gain is defined from such a viewpoint; (3) There exists a jumping phenomenon in the oscillator output, when the frequency of the injection signal is varied. This is the result of a sudden change of the injected signal frequency affecting the amplitude to an on‐off behavior. This property can be applied to the detection of FSK signal. These results of analysis were compared with the experiment, and satisfactory agreement was obtained.
Finite‐element solution of three‐dimensional electromagnetic eigenvalue problems
Authors: Koshiba Masanori , Katano Toshio , Suzuki Michio 
Published: July 2007

AbstractA three‐dimensional finite‐element method for determining the vector fields within a closed system containing inhomogeneous materials of arbitrary shape is described in terms of all three components of the magnetic field vector. One drawback associated with the powerful vector formulation is the appearance of spurious, nonphysical solutions. A modified functional has been introduced to reduce the spurious solutions. To show the validity and usefulness of this formulation, examples are computed for resonant frequencies of normal modes in a rectangular cavity partially loaded with dielectric.
An under‐snow radar using multifrequency holography
Authors: Sakamoto Yuji , Takahashi Yukinobu , Iijima Yoshihiro , Aoki Yoshinao 
Published: July 2007

AbstractWith a view to creating images of the interior of snow and detection of an object buried in snow, an under‐snow radar has been fabricated and tested using microwave holography. Since the accumulated snow consists of numerous layers and is not uniform, conventional microwave holography exhibits poor resolution in the distance direction due to unwanted reflection from the interior and hence it is difficult to detect a buried object. To rectify this situation, a multi‐frequency hologram is used so that the resolution in the distance direction is improved and a clearer image is obtained. In this system, data collection and processing are carried out with a microcomputer and, as a result, a flexible and quasi‐real time numerical image reconstruction is possible compared to the optical processing. In the experiment with this system, a metal object less than 1 mm long can be detected in the snow. Thus, the feasibility of the image reconstruction of the object in the snow is demonstrated. Further, the snow surface and the ground surface under the snow can be detected and hence the amount of snow accumulation may be determined. However, it is still necessary to estimate various parameters such as the dielectric constant of the accumulated snow. The problem of reconstruction in a multiple medium is left unsolved.
Sampling and recovery formula in finite HANKEL transform based on the minimum‐norm principle
Authors: Araki Kiyomichi 
Published: July 2007

AbstractIt is known that the sampling theorem applies to the waveform after band‐limited transformation. It frequently happens as in the case of the far visual field of an image where only a finite number of sampling points are available, in the waveform after Hankel transform, for which the spectrum is limited to a finite region. Yen introduced a restoration formula based on the minimum‐norm principle for the finite Fourier transform waveform to restore the original waveform from such a finite number of sampled points. The method was discussed in detail by Kishi and Sakaniwa. This paper applies the idea of Hankel transform and presents several theorems indicating that the interpolation ability of the formula is better than that of the past formula by Dini's expansion. The effectiveness of the method is demonstrated by a numerical example. The proposed restoration formula requires a little more complex numerical calculation but the realized interpolation accuracy is far better both in waveform and in norm.
An analysis of electromagnetic near field around a truncated end of dielectric waveguide with rectangular cross section
Authors: Matsumura Kazuhito , Ueda Toshikazu , Tomabechi Yoshiro 
Published: July 2007

AbstractThe reflection coefficient of the guided mode and near‐field radiation pattern in front of the truncated end of a dielectric waveguide with rectangular cross section are analyzed numerically. The procedures are as follows: (1) The electromagnetic field along the dielectric waveguide is exprssed in terms of the guided mode and radiation mode. (2) Two field equations which must be satisfied by the boundary conditions at the end surface of the waveguide are defined. (3) The two‐dimensional Fourier transformation is applied to the field equations to obtain the spectral representations of each mode. (4) By determining the ratio of the electric and magnetic field components under the conditions that the mode spectrum must be satisfied with mutual orthogonality, the reflection coefficients of the guided and radiation modes at the truncated end can be obtained. (5) Finally, applying inverse Fourier transformation to the spectral electric distribution at the guide end, we calculate the near‐field electric distribution pattern in front of the truncated end of the rectangular dielectric waveguide. The analytical results are found to agree with experimental results. Several investigators have analyzed the problem of a dielectric waveguide discontinuity by using the approximated slab waveguide model. However, it is difficult to use the slab model to calculate the effects of transverse displacement of rectangular dielectric waveguides.The results obtained in this paper are very advantageous for analysis of the problem of a waveguide discontinuity displaced in the transverse plane. The analytical method of this paper is applicable to the design of rectangular dielectric waveguide components such as couplers, dividers, etc.
Higher‐order bragg diffraction by dielectric gratings
Authors: Yamauchi Norikatsu 
Published: July 2007

AbstractThis paper analyzes the diffraction of a TE‐polarized plane wave incidence from a dielectric grating based on the modal expansion in which the orthogonalities of the Mathieu functions are used as almost periodic functions. This method provides good convergence particularly when the incident angle of the incident plane wave is close to the Bragg angle. As numerical examples, the incidence of a plane wave with a particular wave number for a given diffraction grating is shown for the incident angle near the first‐, second‐, and third‐order Bragg angles. The diffraction efficiency versus the grating thickness has been studied for the incidence at the first, second and third Bragg angles. The angular selectivity has also been investigated in the case where the incident angle is deviated from the Bragg angle of each order for the grating thickness for which the perfect extinction condition is satisfied for a straight‐through wave. On the anomalous diffraction due to the slab mode excited in a grating with its average dielectric constant larger than that of surroundings, the case of near second‐order Bragg angle incidence has been studied in detail. In the Appendix, new expansion coefficients of the Mathieu functions found by the Whittaker's method are provided for use in the analysis for near even‐order Bragg angle incidence.
Offset frequency allocation to reduce intermodulation noise
Authors: Nakajima Shigeo , Sakai Tsutomu , Mishima Hiraku 
Published: July 2007

AbstractIn SCPC satellite systems intermodulation (IM) noise is generated due to transponder nonlinearity. It is known that this noise can be reduced by proper signal frequency allocation. In the conventional method the signal frequencies are allocated at integral multiples of a basic interval, that is, the minimum signal frequency separation. This paper is concerned with offset frequency allocation in which the signal frequencies are not necessarily integral multiples of a basic interval. Specifically, the IM noise power spectrum is analyzed for 2‐phase PSK signals and studies are made for the IM power reduction characteristics after passing the receiving filter, specific signal frequency allocations with reduced IM noise and IM noise improvement over equal‐interval frequency allocation. Also, starting with the Babcock allocation, offset frequency allocations are derived and their IM characteristics and frequency bandwidth are evaluated.
An algorithm for multicommodity flows in a class of planar networks
Authors: Suzuki Hitoshi , Nishizeki Takao , Saito Nobuji 
Published: July 2007

AbstractThis paper presents a polynomial‐time algorithm for finding multicommodity flows in planar graphs. Suppose that G is an undirected planar graph and that some of the source‐sink pairs are located on the boundary of the outer face and all the other pairs share a common sink located on that boundary. The algorithm determines whether G has multicommodity flows each from a source to a sink and of a given demand, and if it does, actually finds them.Let n be the number of vertices in G and b be the number of edges on the boundary of the outer face. Then the time complexity of the algorithm is O(n(b2 + T+(n)), where T+(n) is the time required to find the shortest paths from a vertex to the others in a planar‐directed graph with n vertices and nonnegative real weighted edges. In the class of planar networks treated in this paper, it is known that the so‐called “Max Flow ‐ Min Cut theorem” holds.
Synthesis of impedance transformable filter by artificial nonuniform transmission line with distortionless property
Authors: Takase Tadahiro , Nagasawa Masato , Ito Chiaki 
Published: July 2007

AbstractThis paper proposes a simple synthesis method of impedance matching and transforming filter. This method is based on the use of a multistage ladder network simulating a nonuniform transmission line. When the filter charactersitic functions defined in this paper satisfy the distortionless conditions of the voltage and current waveforms the artificial transmission line mentioned above almost operates as an ideal lowpass filter. As an example the characteristics of 1 ‐ 2ω transformable type lowpass filter are evaluated and the obtained results almost satisfy the conditions for the ideal filter.
A method for signal approximation using minimum norm signal
Authors: Uyematsu Tomohiko , Sakaniwa Kohichi 
Published: July 2007

AbstractThis paper shows that a fundamental signal called a “minimum norm signal” can be defined for a class of piecewise continuously differentiable signals in the time domain; the energies of the original signals and differentiated signals are both finite. Making use of minimum norm signals, this paper also presents an efficient signal approximation method. The minimum norm signal is defined as a waveform of minimum norm which takes specified sample values at given sampling points. The proposed approximation algorithm adds a new sampling point at a position which minimizes the integrated square error between the original signal and an approximate signal. This method adds the optimal sampling point at each stage and sequentially constructs the minimum norm signal with small approximation errors. Compared with a conventional approximation method using the orthogonal function system, the proposed method does not require integral calculation and is free from numerical integration error. Moreover, the sequence of approximate signals uniformly converges to the original signal as the number of sampling points tends to infinity.
Design of two‐dimensional digital fan filters with complex coefficients using 90‐degree phase‐difference network
Authors: Hsueh Sung‐Chu , Takahashi Shin‐Ichi , Baba Yoshi‐Aki 
Published: July 2007

AbstractIn two‐dimensional digital filters with complex coefficients, design flexibility is gained and the filter order can be lowered as compared with real coefficient filters. On the other hand, in the signal theory, the concept of analytic signal is well known in connection with single side‐band amplitude modulator, which can be implemented by using a bandpass filter or a 90‐degree phase‐difference network. The latter implementation, which uses all‐pass networks, yields far better characteristics as compared with the former.The conventional fan filter with complex coefficients is designed by shifting one‐dimensional low‐pass digital filters with a cutoff frequency of 0.5 π on the real frequency axis and applying a variable transformation. In contrast, we propose a new design method of fan filters with complex coefficients that combines the approach of the forementioned 90‐degree phase‐difference network for the single sideband amplitude modulation and the theory of complex coefficient filters; i.e., two all‐pass networks with 90‐degree phase‐difference are used in the new fan filters.
Evaluation of EDB code in optical fiber communication systems
Authors: Ohishi Tomofumi , Takahara Mikio 
Published: July 2007

AbstractOptical fiber is generally believed to have a wide band but the step type or some of the graded‐type fibers have a narrow band and hence a narrow‐band code is necessary for high bit rate transmission or a long repeater interval. In the system with signal‐dependent noise, such as the optical fiber communication system, the optimum code levels of a multilevel code are spaced unequally when the average light power is prescribed. In this paper three types of codes — the duobinary code typical of a narrow‐band transmission code, the extended duobinary code with three unequally spaced decision levels, and the conventional binary code — are compared with respect to the maximum transmission distance. Also, the difference of maximum transmission distances of duobinary code and binary code is calculated with the fiber bandwidth as a parameter and the range in which the duobinary code and extended duobinary code are advantageous over the binary code is clarified. As an example, when the oscillation wavelength=0.85 μm, the fiber bandwidth=100 MHz · km, length‐dependent parameter of fiber=0.7, BER=10−9 and bit rate=200 Mbps, maximum transmission distances of duobinary code are about 1.8 times and about 2 times that of the binary code, respectively.