bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recognition of human activities by gas sensor response using genetic algorithm
Authors: Hayashi Takahiro , Kimura Haruhiko , Oyabu Takashi 
Published: August 2002

AbstractIn this paper, a scheme for estimating gas concentration change signals for each gas generating source in a room from output signals of a combustible gas sensor installed in the room, and for estimating event signals synthesized from them by a genetic algorithm (GA), is proposed. It is shown by computer simulation that more accurately estimated concentration change signals or event signals are obtained by applying selective weeding, crossing, mutation, and so on, repeatedly to an individual group, while applying an appropriate evaluation function to concentration change signals and event signals estimated for each gas generating source expressed by a GA individual. In addition, it is shown that the estimated concentration change signals and estimated event signals obtained from the output signals of a gas sensor installed in an occupied room by the proposed scheme correspond approximately to human activities. In addition, it is shown that the proposed scheme is effective in detecting human activities with a gas sensor, since appropriate signals can be estimated robustly even though components such as noise may be present in the sensor output signals. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 85(1): 50–61, 2002
Transient analysis of nonuniform transmission line using the finite difference time domain method
Authors: Sekine Toshikazu , Kobayashi Kunikatsu , Yokokawa Senji 
Published: August 2002

AbstractWith a view to accurate and fast time domain analysis of nonuniform transmission lines, a method is presented for applying the FDTD method to a finite length nonuniform transmission line. A step response analysis is carried out for a parabolic line as one of the nonuniform transmission lines. Effectiveness of this approach is confirmed by comparison with analytical solutions and other methods. An equation for the voltage at the initial rising duration of the step response of a nonuniform transmission line is derived. It is shown that if the nonuniform transmission line has the characteristic impedance with a continuous distribution the initial arriving voltage can be determined by the characteristic impedance at both ends of the transmission line. As an application, a method is described for approximating the step response waveform of a parabolic line to a step wave. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 85(2): 22–31, 2002
Lock‐in time characteristics of double correlator delay lock loop
Authors: Kishibe Shinichi , Imamura Akitaka , Sato Masashi 
Published: August 2002

AbstractAs a lock tracking system for the spread spectrum communication scheme, the delay lock loop (DLL) has been widely used for a long time. However, when code division multiple access (CDMA) is carried out, signals from other stations in communication at the same time exist as interference. In the DLL, the correlation output is decreased due to the steady‐state phase error, and, as a result, the bit error rate is degraded. Hence, in this paper, a double correlation DLL is proposed as a locking system that can eliminate this steady‐state phase error. A theoretical equation is derived for the time needed for locking (lock‐in time) and for the mean time from the locked state to the unlocked state due to noise (mean time to lose lock). By means of these equations, the locking characteristics of the double correlation DLL are studied and a method for setting appropriate parameters is discussed. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 85(2): 43–51, 2002
Directional difference filter: its effectiveness in the postprocessing of noise detectors
Authors: Hashimoto Yuuhei , Kajikawa Yoshinobu , Nomura Yasuo 
Published: August 2002

AbstractIn this paper, we propose a directional difference filter that possesses superior noise removal for images corrupted by additive impulse noise and a high level of original signal preservation. By estimating the pixel value of the processing point from directional shape information about the edges and successively updating the estimate, the proposed filter can prevent residual noise even when impulse noise generated at a high probability was added. In addition, this process can perform original signal preservation robust to the detection errors of the noise detector and is extremely useful as a postprocess for a noise detector that is used to remove noise generated at a high probability. In this paper, we demonstrate the robustness of the proposed method to the detection errors generated when using an actual noise detector and use processing examples to verify the superior image processing results over conventional noise removal filters. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 85(2): 74–82, 2002
Magnetic noise compensation using FIR model parameter estimation method
Authors: Inaba Takayuki , Shima Akihiro , Konishi Masaharu , Yanagisawa Hajime , Takada Jun‐ichi , Araki Kiyomichi 
Published: August 2002

AbstractFor magnetic noise compensation in the field of detection (magnetic anomaly detection) of magnetic dipole targets (such as sunken ships) by magnetic sensors carried on an aircraft, a quadratic method of compensation of scalar magnetic sensors has been reported. However, in order to use a highly sensitive vector magnetic sensor such as a superconducting quantum interference device, it is necessary to obtain the scalar magnetic field (intensity of the magnetic field) accurately from the three‐axis vector field. Also, in quadratic compensation, a special flight is needed, imposing a significant burden on the platform crew members for the acquisition of data for quadratic compensation. In the present paper, an FIR (Finite Impulse Response) model parameter estimation method is proposed that allows magnetic noise compensation for a three‐axis vector magnetic sensor without a special flight. The experimental data confirm the effectiveness of the proposed FIR model parameter estimation method. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 85(3): 1–11, 2002
A Fast Convergence Algorithm of Volterra Adaptive Filters
Authors: Chao Jinhui , Uno Shinpei , Kubota Tomonori , Inomata Atsushi 
Published: August 2002

AbstractVolterra nonlinear adaptive filters are known to be superior, having characteristics of general applicability to nonlinear systems and global convergence which is guaranteed by a gradient adaptive calculating algorithm. However, such convergence can become slow and unstable easily when Volterra nuclei are dense. In this paper, the authors have derived theoretically important properties of the error curve shape of Gaussian signal inputs in a second‐order Volterra nonlinear adaptive filter. On the basis of these analytical results, a fast convergence algorithm using a corrected direction and a renewed amplitude of an optimal weighting coefficient vector for white signal inputs and colored signal inputs is proposed and its efficacy is verified by computer simulations. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 85(4): 56–65, 2002
An extension of simultaneous equation method to multiple channel active noise control system
Authors: Muneyasu Mitsuji , Asai Takashi , Fujii Kensaku , Hinamoto Takao 
Published: August 2002

AbstractWhen a region with a certain area needs silencing, no sufficient effect can be obtained with a single‐channel active noise control system. Therefore, multiple channel noise control systems using several microphones and speakers have been proposed. One of the algorithms used frequently is the Multiple Error Filtered‐X (MEFX) method. The MEFX method requires prior estimation of the error path system. In the case of multiple channels, the estimation error poses more complex effects in comparison to the single channel. In addition, variations of the system during operation are problematic. In this paper, the simultaneous equation method recently proposed for the single channel in which no estimation is required for the error path system is applied to the multiple channel active noise control. In the present procedure, the coefficients of the noise control filter can be estimated without estimation of the error path system as in the case of the single channel. The method can handle the variation of the path during operation and can obtain excellent silencing effects. © 2002 Scripta Technica, Electron Comm Jpn Pt 3, 85(5): 46–55, 2002
Theoretical study of hyperparameter estimation by maximization of marginal likelihood in image restoration by means of cluster variation method
Authors: Tanaka Kazuyuki 
Published: August 2002

AbstractFrom the perspective of maximum likelihood estimation, the hyperparameters that appear in the statistical methods for image restoration are determined by maximizing the quantity referred to as the marginal likelihood. Rigorously calculating the marginal likelihood for the Markov random field model is extremely difficult, and approximate analysis techniques must be introduced. A well‐known conventional approximate analysis technique is mean field approximation. In this paper, we propose a novel approximate analysis technique that uses the cluster variation method instead of mean field approximation to more accurately estimate hyperparameters than estimation using the marginal likelihood. The cluster variation method is a typical approximate analysis technique in statistical mechanics obtained by extending mean field approximation and can obtain some statistical quantities of the Markov random field model with high accuracy. However, the cluster variation method has not been applied to hyperparameter estimation employing the marginal likelihood. Compared to the results of earlier mean field approximation often used as the marginal likelihood approximate analysis technique, numerical experiments show that hyperparameter estimation using the cluster variation method produces better restorations particularly of images that closely reflect the prior probability distribution. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 85(7): 50–62, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1107
The improvement of computational efficiency of three‐dimensional sound field analysis by boundary element method using two‐level fast multipole method
Authors: Okumura Yohzoh 
Published: August 2002

AbstractWhen the boundary element method (BEM) is applied to a large‐scale three‐dimensional sound field problem, rapid increase of the computing time and required memory storage is a significant problem as the number of unknowns N is increased. To cope with this situation, the authors have demonstrated that the introduction of the fast multipole method (FMM) is effective and that the amount of computation and the storage requirement can be reduced from O(N2) to O(N1.5) by this method. In the present research, with a view to further improvement of efficiency, the FMM using a two‐level multipole expression is introduced into the three‐dimensional steady‐state sound field analysis by the BEM. It is shown that the computational and memory‐requirement complexities can be reduced to O(N4/3). © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 85(8): 30–37, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1110
Improvement of noise robustness for formant frequency extraction based on linear predictive analysis
Authors: Zhao Qifang , Shimamura Tetsuya , Takahashi Junichi , Suzuki Jouji 
Published: August 2002

AbstractIn this paper, we study improving the noise robustness of formant frequency extraction based on linear predictive analysis by using the noise reduction ability of the autocorrelation function. The autocorrelation function has the property of concentrating the noise components in the short delayed parts of speech signals corrupted by white noise. We believe that the noise robustness of formant frequency extraction can be improved by utilizing the above property and using the autocorrelation function of the speech signal instead of the signal itself in formant frequency extraction. In this paper, we analyze the principle behind extracting the formant frequency from the autocorrelation function and examine this problem and a possible solution in detail. Then based on this analysis, we propose Method 1 that performs linear predictive analysis of the autocorrelation function of the speech signal. Then we verify from the experimental results that an extraction accuracy at the same level as the conventional method is obtained for a clean signal by Method 1, and the extraction accuracy is significantly improved over the conventional method for speech corrupted by noise. However, inadequate extraction accuracy is also indicated in a very noisy environment, and we analyze the cause and propose Method 2 as an improved method that subtracts the autocorrelation function. The experimental results show that when the signal‐to‐noise ratio is 15 dB or less, the formant frequency extraction error (Average Absolute Error) in Method 2 is kept to about one‐third the error of the conventional method and about one‐half the error of Method 1. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 85(9): 1–14, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1114
A clustering/labeling analog LSI architecture for media recognition
Authors: Kabasawa Masayuki , Miyanaga Yoshikazu , Hataoka Nobuo 
Published: August 2002

AbstractClustering and labeling are basic processes in speech and image recognition. In this paper, we present the design of an analog circuit for a clustering and labeling system and the performance evaluation results based on a simulation. The number of basic computation modules becomes huge when digital LSIs are designed for parallel processing. It becomes one reason for the increase in the chip area. Therefore, we propose an architecture for a clustering/labeling circuit. It introduces the similarity circuit that utilizes the fundamental characteristics of MOS and the C matrix circuit that outputs the results of the matrix computation. We use this circuit to conduct a circuit simulation that includes statistical analysis and confirm the ability to perform feature clustering of simple speech. The proposed analog circuit has an extremely simple architecture and is expected to decrease the chip area by about 1/36 compared to an 8‐bit digital design. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 85(10): 1–7, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1120
A restoration method of image sequences which are corrupted by blotches
Authors: Miyata Koji , Taguchi Akira 
Published: August 2002

AbstractThe digitization and restoration of images that have been degraded by white or black blotches seen in motion picture films prior to the 1950s have attracted attention. Conventional restoration methods are composed of two processes. The first process is motion estimation by block matching (BM). The second process matches the current frame to the previous and next frames based on the motion estimates and filters in the temporal direction. Blotch detection accompanies the filtering in the second process. The BM used in the first process is average BM or sorted BM. Blotch detection in the second process employs Spike Detection Index‐a (SDIa). In conventional BM, however, there are limits to the accuracy of motion estimation when blotches are present in the blocks used to estimate the motion in images corrupted by blotches. Furthermore, the accuracy of the filtering in the second process is affected by the accuracy of the motion estimation. And although blotch detection based on SDIa is a simple method, the accuracy of its blotch detection is a problem. To solve these problems in this paper, we create a blotch position image by using a median filter with an iteration constraint as the first stage, and obtain a virtual original image with the blotches removed by filtering based on the blotch position image. The accuracy of the motion estimation is improved by using the virtual original image, and the accuracy of the filtering is improved by using the blotch position image in the filtering. Based on these innovations, we propose a new method to obtain a restored image sequence having enhanced image quality. The effectiveness of the proposed method is clearly demonstrated through a variety of examples. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 85(10): 8–18, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1121
Development of an adaptive array based on subband signal processing
Authors: Kamiya Yukihiro , Denno Satoshi , Mizuguchi Yoshihiko , Katayama Masaaki , Ogawa Akira , Karasawa Yoshio 
Published: August 2002

AbstractAdaptive arrays for spatiotemporal signal processing are expected to be effective multipath measures in future high‐speed mobile communications systems. However, a problem is the tremendous computational load in a hardware implementation because the number of weights that are adaptively controlled becomes extremely large. Therefore, the key to its practical use is to reduce the computational load. In this paper, an adaptive array for processing subband signals that can substantially reduce the computational load was implemented in hardware by using a commercially available digital signal processor (DSP). First, we illustrated the scale of the hardware by the number of DSPs needed in each unit that performed the required signal processing. Next, we built a simple multipath environment of two waves in an anechoic chamber and performed experiments to demonstrate the basic performance and verified that performance nearly equal to the theoretical values was obtained. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 85(10): 19–30, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1122
A formulation of the convergence property for the second‐order adaptive volterra filter using NLMS algorithm
Authors: Takahama Yuri , Kajikawa Yoshinobu , Nomura Yasuo 
Published: August 2002

AbstractIn this paper, a formulation of the convergence property of the NLMS method, an updating algorithm for an adaptive Volterra filter, is discussed. To date, much research has been carried out on the convergence property of the updating algorithm in a linear adaptive filter. However, there has been insufficient study of the updating algorithm for the second‐order adaptive Volterra filter. In this paper, the convergence property of the E‐NLMS method, an updating algorithm in the second‐order adaptive Volterra filter, is formulated and the convergence property of the second‐order adaptive Volterra filter is theoretically determined. In the formulation of the convergence property we use the first‐order recursive filter expression, which is effective for studying various characteristics of the NLMS method in linear adaptive filters. In addition, it is recognized that the nature of the input signal to the diagonal (D) elements of the second‐order Volterra system is different from that of the input to the other (ED) components. By means of computer simulation, it is confirmed that the convergence property given by the derived theoretical equation can sufficiently express the actual convergence property. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 85(10): 40–50, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1124
Laser‐induced burst corona and streamer corona for a positive DC nonuniform field gap in N2/NO mixtures
Authors: Izawa Yasuji , Yang Jian‐Bo , Nishijima Kiyoto 
Published: August 2002

AbstractThe characteristic of sparkover in a DC nonuniform field gap is closely related to the discharge mode at the onset time of corona. In order to investigate the transition mechanism from burst corona to glow corona or streamer corona, a discharge experiment which is controlled by a pulsed laser in N2/NO mixture has been performed.From highly sensitive observation of discharge luminescence which corresponds to the discharge current wave, the transition from burst corona to streamer corona is identified by the electron avalanche, which is formed initially at the tip of the rod electrode with the highest electric field, and the effect of secondary ionization. Moreover, it is verified that the measured electron burst drift time with laser irradiation in the discharge gap is determined by the electric field of the discharge gap. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(2): 10–17, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10007
Compensation for magnetizing inrush currents in transformers using a PWM inverter
Authors: Shinohara Katsuji , Yamamoto Kichiro , Iimori Kenichi , Minari Yoshitaka , Sakata Osamu , Miyake Michio 
Published: August 2002

AbstractWhen a transformer is connected to a circuit, under certain conditions, magnetizing inrush currents may be about ten times the full load current of the transformer. The currents contain a large amount of harmonic components and cause some relays to trip out. In this paper, the magnetizing inrush currents are compensated using a PWM inverter. The magnetizing inrush currents are detected and the PWM inverter generates compensating currents for the inrush currents. Hysteresis current controllers are used for fast response. The validity of this compensation is investigated by the simulation results. In addition, hardware implementation for the compensator is accomplished to verify the simulation results. Moreover, for the compensator, the relation between the compensating characteristics, the maximum switching frequency, and the coupling reactor is discussed based on the simulation results. Finally, characteristics of two current controllers (hysteresis band current controller and ramp‐comparison controller) are compared and it is shown that the hysteresis band current controller is more suitable for the compensator. The PSCAD/EMTDC electromagnetic transient simulator is used for the simulations. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(2): 53–64, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10023
Development of a 70‐MW‐class quick response excitation superconducting generator
Authors: Imai Yoshihiro , Nagamura Hidehiro , Kusafuka Hiroshi , Shibuya Masatoyo , Hasegawa Hiroshi , Miyaike Kiyoshi , Shiobara Ryoichi 
Published: August 2002

AbstractA superconducting generator is expected to be a next‐generation machine due to its many advantages over a conventional generator. Super‐GM has been promoting R&D of 70‐MW‐class superconducting model generators to verify the basic technologies required for the design and manufacture of a 200‐MW‐class superconducting pilot generator. Verification tests of the third model generator, quick response excitation type C generator, were finished in June 1999. The excellent characteristics as a superconducting generator were verified through the series of tests. We report main test results such as “open and short‐circuit test,” “loaded test,” “quick excitation test,” “negative‐phase sequence overcurrent test,” and “sudden short circuit test.” © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(1): 22–29, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10029