bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rotary ultrasonic motor utilizing contour and flexural vibrations of a rectangular thick plate
Authors: Iijima Tamotu , Nakagawa Yasuhiko , Ito Hiroshi 
Published: July 2007

AbstractA method of vibration analysis for an ultrasonic motor using asymmetric flexural vibrations and symmetric contour vibrations of a thick rectangular plate is given. An investigation of the symmetricity of the flexural vibrations using the Rayleigh quotient is used to derive an expression for the resonant frequency of the same flexural mode and the similarity ratio of the vibration plate thickness and contour dimensions. The possibility of estimating the resonant frequency of a rectangular plate of different dimensions is then confirmed experimentally.With the contour vibration mode with small displacements at the middle and large displacements at the ends, the middle side constrained is analyzed. The vibration plate was an SUS304 rectangular plate with a PZT plate attached; as in the case of the PZT rectangular plate, it is confirmed experimentally that shear stress can be neglected. When allowance is made for machined holes in the vibration plate (such as screw holes), a value close to the measurement value is still obtained.
Image reconstruction based on zero‐crossing representations of wavelet transform
Authors: Cheong Cha Keon , Aizawa Kiyoha , Hatori Mitsutoshi , Saito Takahiro 
Published: July 2007

AbstractThis paper discusses a reconstruction method of the image signal from the zero‐crossing representation. First, the one‐ and two‐dimensional multiscale wavelet transforms are described which have the completeness and the translation invariance. A new zero‐crossing representation is proposed in which the zero‐crossing points are extracted from the multiscale wavelet transform. the information concerning the maximum value (the minimum value when negative) between two consecutive zero‐crossing points as well as its position is combined. Then it is shown that the original signal can be reconstructed with a stable and fast convergence from the zero‐crossing representation of the signal through the iterated projections to the convex set.The effect of the wavelet basis filter on the convergence in the reconstruction is investigated, and a necessary condition for the optimal basis filter is derived considering the convergence.Finally, a new basis filter is designed using the B‐spline function and the usefulness of the proposed method is demonstrated for the one‐dimensional signal and the image signal. It is shown also that the signal reconstruction procedure converges with stability, even if there exists an error at the extracted zero‐crossing point.
Design of short tap perfect reconstruction filters for subband coding of images
Authors: Komatsu Kunitoshi , Sezaki Kaoru , Yasuda Yasuhiko 
Published: July 2007

AbstractShort tap filters reduce the computational complexity of filtering processes and also reduce image degradations associated with ringing effects near edges in image subband coding. When the number of taps is reduced, however, coding performance generally deteriorates. In this paper, short tap filters that satisfy isolated perfect reconstruction constraints are designed so as to improve coding performance. For the sake of comparisons, linear phase‐ and orthogonal filters are also designed. Filters with coefficients determined by the values 2nare designed to reduce further the computational burden of the filter process. Assuming that the input can be modeled by an AR(1) process, the set of parameters which determine the tap coefficients are selected to maximize the coding gain. the relationship between signal‐to‐noise ratio and entropy is determined to evaluate coding performance. the superior coding performance of the perfect reconstruction filters shows no degradation when subjected to an integer coefficient constraint. Also, filters with coefficients determined by the values 2nand excellent coding performance are obtained.
Pseudodiagonalization of the autocorrelation of a stochastic process by an over‐complete wavelet system
Authors: Sakaguchi Fuminori 
Published: July 2007

AbstractIf a stochastic process can be regarded as a superposition of the wavelets which arise randomly and independently of one another, the random‐wavelet picture of a stochastic process is intuitive and convenient. This paper investigates theoretically in what case the picture can be used; i.e., in what case the autocorrelation of the stochastic process can be diagonalized by using the over‐complete wavelet system. A general method for calculating the pseudodiagonal form from an arbitrarily given autocorrelation function using the operator algebra is proposed. Next, some properties of stationary wavelet‐diagonal processes are investigated where it is shown that the power spectra of these processes are related to the spectral estimates under the circumstances in which the number of the time points are constrained to a constant finite number.
Evaluation of analog printed circuit board wiring routes by surface charge modeling method and applicatuion to the determination of wiring
Authors: Kasuga Masatoshi , Konta Isamu , Matsuda Jin‐Ichi 
Published: July 2007

AbstractA surface charge modeling method is one of the routing methods based on strategies that minimize network energy. The relationship between potential energy and typical routing criteria is theoretically investigated first. It is concluded that the minimal energy state coincides with the minimal wire length in case of the sufficiently large printed circuit boards (PCBs). Then a procedure for improving wiring starting from an initial wiring which is a minimal route connecting terminal pairs in a straight line is described. This technique has the advantage of not requiring wiring specification priorities and obtaining the wiring routes of the shortest‐path topology.
Optimal design of infinite impulse response hilbert transformers
Authors: Shimizu Satoru , Yahagi Takashi , Henriques Marco A. A. 
Published: July 2007

AbstractThis paper proposes a new method for designing the optimal infinite impulse response (IIR) Hilbert transformer. Until now, finite impulse response (FIR) filters have mostly been used in the design of the digital filter for the circuit such as the Hilbert transformer, where the linear‐phase response is required. Several methods have been proposed for designing the IIR filter, which, however, had problems in the complexity of the algorithm or the accuracy of the designed Hilbert transformer.This paper considers first the FIR Hilbert transformer as a model. the design of the tap coefficients for the IIR filter which gives the same output as that of the model, when the same input is given, is reduced to the parameter estimation problem when the Kalman filter is used for control. Then the IIR Hilbert transformer is designed in the time domain.To obtain a better response, an evaluation funclion is defined that represents the error from the ideal frequency response. the tap coefficients are fine‐adjusted by the Fletcher‐Powell method so that the evaluation function is minimized. By this approach, it is possible to design the IIR Hilbert transformer while maintaining the stability and the phase linearity, which are the features of the FIR filter. the 16th‐order IIR Hilbert transformer actually is designed by the proposed method, and it is shown that a performance better than the 30th‐ and the 31st‐order reference FIR Hilbert transformers can be realized.
An age replacement policy for a hard disk considering failures of sectors
Authors: Hirakoshi Hiroyuki , Sandoh Hiroaki 
Published: July 2007

AbstractHard disk drives are an indispensable element of modern computer systems and their failure often causes loss of precious data. Hard disks are encapsulated to prevent contamination; a defect of any of the encapsulated mechanical components means that no data can be accessed. Another type of hard disk effect is disk sector failure: in this case only a relatively small amount of data can be lost and the failed sector can be replaced by a spare sector. This ensures that the drive is fully functional. However, the number of spare sectors is limited: If the number of failed sectors exceeds it, the drive is written off. This paper, taking into consideration the forementioned two drive‐defect types, discusses a strategy for preventive replacement of hard disk drives. Expected replacement cost is expressed analytically, and the function is then minimized, leading to the optimum age replacement strategy in terms of cost.
Speech coding based on adaptive mel‐cepstral analysis and its evaluation
Authors: Tokuda Keiichi , Kobayashi Takao , Imai Satoshi , Fukada Toshiaki 
Published: July 2007

AbstractThis paper proposes the ADPCM speech coding system using mel‐cepstrum as the parameter for the short‐term prediction. In the proposed coding system, the backward type adaptive prediction is applied based on the adaptive mel‐cepstrum analysis. Operations such as noise shaping and postifitering are executed through the melcepstrum. Consequently, it is expected that the noise shaping and the postfiltering have the effect which is matched to the human auditory characteristics.This paper presents the configuration of the coding system with some improvements such as the addition of the pitch predictor, and the quality of the coded speech is evaluated. It is shown as a result that the proposed coding system realizes the same speech quality at 16 kbit/s as that of the 32‐kbit/s ADPCM, even though there is no algorithm delay.
NP‐completeness of interval graph completion from a path graph
Authors: Yamaguchi Kazuaki , Araki Toshiro , Kashiwabara Toshinobu 
Published: July 2007

AbstractGiven a set of paths on a tree, the graph with vertices corresponding to the paths, where the corresponding vertices are connected by an edge when two paths intersect, is called the path graph. Given a set A of finite intervals on a straight line, the graph with vertices corresponding to the intervals belonging to A, where an edge is provided when two intervals intersect, is called the interval graph.In this paper, it is shown that the problem to decide whether or not a given path graph can be converted to an interval graph by adding K or less edges is NP‐complete.
Decoding mechanism of a scarce state transition‐type viterbi decoder for general nonsystematic convolutional codes and its asymptotic behavior on a very noisy channel
Authors: Tajima Masato 
Published: July 2007

AbstractWhen a scarce state transition (SST) Viterbi decoder is used to decode general nonsystematic convolutional codes (not included among quick look‐in (QLI) codes), metrics based on the maximum a posteriori probability (MAP) estimation method must be computed in order for the main decoder to operate under the criterion of minimizing the decoding error probability. In this case, however, it becomes necessary to extend the original code trellis structure by introducing augmented trellis states in order to incorporate the newly induced correlation among the apparent information sequence.This paper shows that the extended trellis degenerates into the original one as the channel error probability q approaches one‐half. By performing an equivalent transformation of metrics, it is shown also that the branch metrics derived based on the MAP estimation method converge to those computed using the conventional one as q approaches one‐half.
Stabilization of the saddle‐type periodic points in phase‐locked loop equation by the OGY‐control method
Authors: Ogawa Takeo , Endo Tetsuro 
Published: July 2007

AbstractIt is well known that the differential equation representing the phase‐locked loops (PLL) can produce chaotic attractor. In particular, since the periodic solution of the second type representing the out‐of‐lock condition can bifurcate to become chaos easily by small external force so its theoretical treatment is possible. Moreover, much research activity has been performed in this area and various interesting points have been confirmed by laboratory experiments.This paper is an attempt to stabilize various saddletype periodic orbits included in the chaotic attractor bifurcated from second‐type periodic solutions by the OGY method. In general, a chaotic attrrator includes a number of saddle‐type periodic orbits, and if one wants to stabilize one of them by the OGY method, one must know various values, e.g., coordinates and eigenvalues, etc., of the periodic points on the Poincaré map. However, there is no method to determine these values, in general.The authors obtained the saddle‐type 1‐, 2‐, 3‐, 4‐, and 8‐periodic orbits included in the chaotic attractor by using the continuation method. By applying the continuation method to the 1‐parameter bifurcation diagram, all parameter values required in the OGY method were determined and stabilization of any one of them was dethonstrated by computer simulation. In particular, the authors tested two OGY methods for N‐periodic orbits. One method needs one change of the control parameter after N mappings of external force, and the second method changes the parameter at every mapping. It was confirmed that the latter method takes a shorter time to achieve control.
Weak formulation of stochastic parabolic systems with subdifferential boundary conditions
Authors: Ishikawa Masaaki 
Published: July 2007

AbstractThis paper discusses the mathematical formulation of the stochastic parabolic system, which is described by the multivalued operator called subdifferential operator, that plays an important role in the modeling of the free boundary problem such as viscoelastic and obstacle problems. For various deterministic distributed systems containing a subdifferential operator, the existence of the strong or weak solution is already shown.With respect to the stochastic distributed system, on the other hand, the existence of a strong solution has not been shown except for the system containing a subdifferential operator of a special convex function. As to the existence of the weak solution, there is a report of the case where the subdifferential operator appears in the interior of the system, but there is no report on the general stochastic system containing a subdifferential operator in the boundary condition. Another point is that a strong constraint is imposed on the initial value and the input function in the proof for the existence of the strong solution.From those viewpoints, this paper aims at ameliorating such a constraint and formulates the system by the weak solution. First, the existence condition for the weak solution is shown. Then it is shown that there exists the maximal solution in the set of weak solutions and an estimate for the maximal solution is derived which has a stronger significance than in the past formulation.
Chaos and fractal properties in EEG data
Authors: Ogo Kiyotaka , Nakagawa Masahiro 
Published: July 2007

AbstractThe purpose of this study is to verify that EEG is composed of frequency components with chaotic characteristics. EEG data are decomposed into frequency components, and the chaos and fractal analyses are applied. More precisely, the running spectrum of EEG is derived and the chaos analysis is applied using the Lyapunov spectrum and the correlation dimension. As a result, the existence of the chaotic phenomenon is verified for most of the frequency components used as the objects of the analysis. It is found also that the fractal properties exist in most of the frequency components. the multifractal analysis is applied to the EEG data, and the generalized dimension of q‐th order is determined. It is seen as a result that the reconstruction attractors of EEG are placed by a nonuniform fractal distribution, which is represented by a large number of scaling indices concerning the dimension.
Optimal checkpointing procedures taking into account system failure caused by checkpointing
Authors: Yanagihara Masayoshi , Odagiri Masanori , Osaki Shunji , Kaio Naoto 
Published: July 2007

AbstractIn the past studies of checkpointing for the computer system, the event that a system failure may be generated due to the checkpointing has not been considered. In practice, it is highly probable that this kind of failure arises in the checkpointing.From such a viewpoint, this paper considers the event where a failure due to the checkpointing is produced at the time of checkpointing and proposes a procedure to derive the optimal checkpointing sequence as the optimal checkpointing strategy. As the evaluation function, the expected cost per cycle and the expected cost per unit time in the steady state are used. the optimal checkpointing strategy is considered to minimize the expected cost.Finally, numerical investigation is made assuming the exponential and the Weibull distributions as the failure time distribution.
Aircraft collision avoidance with potential gradient—ground‐based avoidance for horizontal maneuvers
Authors: Miura Akira , Morikawa Hiroyuki , Mizumachi Moriyuki 
Published: July 2007

AbstractThis paper describes ground‐based avoidance for horizontal maneuvers using a concept of potential as a collision avoidance aircraft procedure. First, mathematical formulation is introduced by using potential as a way to systematically represent the conditions contributing to collision avoidance such as a threat of collision with other aircraft and degrees of deviation from the original course.The flight course with a lower potential is considered safer. In the choice of a specific avoidance course, an avoidance pattern generation method by means of potential gradient is shown. the future location of the aircraft is sampled at a certain time interval. the shift of the sampling point corresponding to the potential gradient at each sampling point or the force applied to each sampling point (attractive or repulsive) is repeated.It was confirmed that by means of this method, avoidance patterns without danger of collision can be obtained with only horizontal avoidance except for special cases. However, when the sampling points are symmetric or when more than three aircraft are involved, the procedure is not adequate and some provisions are needed. to this end, the sampling point arrangement in the initial stage before the avoidance pattern is formed and the three‐dimensional avoidance including vertical avoidance can be considered.
Computer graphics eye‐animation and feeling of gaze line
Authors: Morii Kiyohiro , Kishino Fumio , Tetsutani Nobuji 
Published: July 2007

AbstractIn a teleconferencing system with realistic sensations, human images are generated by computer graphics (CG). This requires animating natural eye movement with CG. This paper describes a real‐time animation technique to generate blinking and gaze shift, while still considering convergence using a graphic workstation. Moreover, the feeling of eye contract is evaluated using this animation. In this experiment, the gaze generated by CG using two‐dimensional (2‐D) or 3‐D display is evaluated subjectively and compared with the gaze of an actual person. Also, an experiment is performed on the time required for perception of eye contact when the eyes of the CG image are moving. Then, a real‐time CG eyeanimation system combined with an eye‐movement detector is described. Also, the allowable transmission delay time when using this system is evaluated subjectively.
Applications of safety index for fault analysis system
Authors: Mineo Yoshiyuki , Suzuki Yoshihisa 
Published: July 2007

AbstractThe safety index is proposed as an index for system reliability. In order to determine this index, the tree analysis for safety (TAS) must be constructed for the individual system. This paper focuses on the hazard source of the fault analysis (FA) system and discusses a method to construct standard TAS, which is independent of the system configuration of the FA system. As a first step, the hazard sources of the FA system are divided into two classes. One is the class in which the existence of the hazard source itself is the problem, and the source must be deleted from the viewpoint of safety (explicit hazard source). the other is the class where the hazard source is indispensable to the FA system; however, a serious event may be produced if an explicit hazard source is generated (potential hazard source). the case where the potential hazard source in the FA system induces an accident is defined as the standard model. the standard TAS is constructed. By providing a selection branch at the lowest level node of TAS, a TAS aligned to the checklist is constructed. By those approaches, it is made possible that a beginner unfamiliar with TAS can determine the safety index. In other words, the safety index is now a useful criterion for the safety evaluation of the FA system.
Two‐step pulse width modulation sinusoidal inverter with modulation switching and frequency spectra
Authors: Arimoto Hideki , Umeda Hisakazu , Yamauchi Yukiji , Kaku Shukichi 
Published: July 2007

AbstractThe pulse width modulation (PWM) in the inverter is an extremely important technology in power electronics. One of the problems in the PWM inverter is the existence of unwanted harmonics caused by switching. In this paper, a method to reduce this unwanted harmonic component, a modulation switching method, is proposed in which the modulation method is switched t the locations such as the peak of the reference sinusoidal signal. the PWM wave train is analyzed by a computer simulation as well as the theoretical analysis by the double Fourier series expansion. It is shown that the present method is effective in the reduction of the unwanted harmonic. Next, the characteristics of the modulation switching two‐stage PWM sinusoidal inverter are investigated.
Computer simulation on nonlinear interaction of intense microwave with space plasmas
Authors: Matsumoto Hiroshi , Hashino Yoshitaka , Yashiro Hiroyuki , Shinohara Naoki , Omura Yoshiharu 
Published: July 2007

AbstractThe concept of a solar power station (SPS) was proposed 25 years ago. During the intervening years, long‐distance, high‐power transmission microwave technology has advanced. Realization of wireless power transmission in space is now no longer a dream. It has been predicted from three‐way coupling that a static plasma wave is excited when an intense microwave passes through space plasma. the microwave power transmission rocket experiment in an ionosphere carried out by the authors (MINIX, Microwave Ionosphere Nonlinear Interaction experiment) has confirmed this fact. In this experiment, a phenomenon that cannot be explained by the three wave resonance theory has been discovered. In this paper, a computer experiment using plasma has been carried out with an electromagnetic particle code. Static plasma wave excitation and the saturation phenomenon are explained in which not only the simple three‐wave coupling but also the wave‐particle interaction are included.
Complex chebyshev approximation for infinite impulse response digital filters
Authors: Okuda Masahiro , Ikehara Masaaki , Takahashi Shin‐Ichi 
Published: July 2007

AbstractIn this paper, a new Chebyshev approximation (amplitude and phase simulataneous approximation) method for IIR digital filters is proposed. the proposed algorithm is based on the Remez algorithm. By solving the eigenvalue problem at each iteration, the frequency characteristic of the filter is interpolated so that the error function in the complex domain is made with equal ripples. Since the previously proposed amplitude and phase simulataneous approximation methods for the IIR digital filters are based on the nonlinear equation, they all require substantial computation. On the other hand, the present method is extremely simple and the amount of compuation can be reduced singnificantly. Nevertheless, the performance equal to or more than the conventional one can be obtained. Further, the present method can be applied not only for the real coefficient filters but also for the complex coefficient filtes. It is possible to carry out characteristic approximation limited to the positive frequency range. Hence, a further reduction of the filter order needed for signal processing can be attempted.