bluuebunny/crossref_metadata_2025_split huggingface dataset:
A theoretical study of recognition of moving objects by monocular vision
Authors: Maruyama Minoru , Amari Shun‐Ichi 
Published: July 2007

AbstractIt is assumed that a human recognizes the movement and 3D‐structure of an object based on the feature quantities and their changes extracted from the retinal images which are the projection of the three‐dimensional object onto the retina. Human recognition of a moving object works as follows. First, primitive recognition takes place based on the change of feature quantity at the local areas corresponding to each small portion on the retina independently. This is local parallel information processing. Second, attention is shifted to the higher level of recognition which integrates all the local primitive recognition. This paper considers the local linear feature of the object. In other words, we consider the infinitesimal plane of the surface of the three‐dimensional object, and we clarify the transformation of the two‐dimensional image caused by the motion of the object. This transformation depends on both the motion of the object and the three‐dimensional structure. Also, we clarify the law of the transformation of the linear features obtained from the image. Based on the above, we show that recognition of the motion of the object and the three‐dimensional structure is possible without the need for identifying the corresponding points. In addition, we demonstrate the condition which the characteristic functions should satisfy, and the concrete computation methods to obtain the motion and the three‐dimensional structure are given.
Simplicial homotopy method for the solution of nonlinear two‐point boundary value problems
Authors: Yamamura Kiyotaka , Oishi Shin'Ichi , Horiuchi Kazuo 
Published: July 2007

AbstractHomotopy methods are useful in determining the solution of nonlinear equations from a remote initial point. Numerous studies have been made to apply the methods to the numerical solution of nonlinear two‐point boundary value problems. However, the method has a disadvantage in that the execution speed is degraded greatly with the increase of the dimension of the system of finite difference equations. This paper proposes an efficient numerical method for the solution of nonlinear two‐point boundary value problems, based on the simplicial homotopy method and the decomposition technique. It is shown first that the system of equations to consider can always be reduced to the system of equations with lower dimension, by applying the decomposition technique to the system of finite difference equations. By this technique, the computational complexity of the algorithm can be decreased drastically compared with the traditional methods. Then an efficient mesh refinement strategy is proposed, taking into consideration the accuracy of the simplicial approximation. Finally, the theorems concerning the convergence of the method are presented and verified by numerical examples. The results are compared with those of the traditional methods, indicating the effectiveness of the proposed method.
Space and frequency correlation characteristics of L‐band multipath fading due to sea surface reflection
Authors: Karasawa Yoshio , Shiokawa Takayasu 
Published: July 2007

AbstractWhen maritime satellite communication is conducted at low elevation angles, fading due to sea surface reflection becomes a problem. For suppression of the fading, space diversity and frequency diversity may be employed. This paper studies the correlation characteristics of multipath fading due to sea reflection in the spatial and frequency domains in L‐band operation. This is important in investigating the diversity effect. First, from the theoretical model of sea surface reflection, the correlation scattering cross sections of the coherent and incoherent components of the reflected wave are obtained. Next, from numerical calculations, the correlation characteristics are obtained with the antenna elevation angle and the height over the sea as the parameters. It is found that in space diversity good diversity effects can be expected from two antennas‐ separated in the vertical direction by about 40 cm. It is also seen that fading reduction cannot be expected with frequency diversity in the case of narrowband communications such as in maritime satellite communications. The effects of various fading reduction measures in the up and down links are considered.
Design and characteristics of sector/cosecant‐square shaped beam antenna
Authors: Yamada Takashi , Kagoshima Kenichi , Itami Yuji 
Published: July 2007

AbstractThe base station antenna for a subscriber radio system is required to have a beam with sector section in the horizontal plane and cosecant‐square beam in the vertical plane. This paper proposes a method for shaping the reflector surface of the antenna so that it forms the required beam in the two planes and also presents the experimental results for a test antenna. It is shown that adequate characteristics can be obtained by this shaping method even for a single reflector. In this method the central cross‐section curve obtained as a solution of a two‐dimensional problem is used as the initial condition and then the reflector coordinates are successively determined from the conditions of the elevation angle of the ray reflected at the surface. The test antenna is a 90° sector beam antenna with aperture of about 52δ in the vertical plane and about 43δ in the horizontal plane. The experimental results indicate a gain of 23.5 dB at the peak and more than 20 dB within an angle of 1.5° in the vertical plane. The antenna beam realizes a sectoral section in the horizontal plane and a cosecant‐square section in the vertical plane to a level as low as ‐10 dBi. The results demonstrate the effectiveness of the present reflector shaping method.
Steady‐state clock phase behavoir in loosely coupled master‐slave synchronization network
Authors: Kihara Masaml , Makino Masatoshi 
Published: July 2007

AbstractIn the Japanese master‐slave synchronization network, the introduction of the cesium atomic beam frequency standard as the master office oscillator for improving the frequency accuracy, and the introduction of a loosely coupled synchronization network using the digital processing type phase‐locked oscillator to improve the clock reliability, are scheduled. An analysis is made of the clock phase behavior of a multi‐link digital clock supply in the steady state. The influence on the clock phase variation by transmission line jitter and DCS (digital clock supply) temperature dependence is considered. The results are expressed by two‐sample variance ßy2(±) which shows short‐term frequency stability, and then by time interval error (TIE) which shows phase fluctuation in the time domain. The results obtained from numerical calculation give maximum TIE of the distributed clock in the domestic 9‐linked DCS (about 25 μs) and a permissible synchronization network within three links for international digital connections by comparison with the TIE recommended by CCITT.
A solution concept in a cooperative n‐person game based on the complaint differences and its application
Authors: Sakawa Masatoshi 
Published: July 2007

AbstractThis paper proposes a new solution concept, based on the minimization, following the lexicographical order, of the complaint differences among coalitions in a cooperative n‐person game in characteristic function form. Such a solution minimizing the maximum complaint difference can be obtained as the pay‐off vector as the inequality constraints sequentially. A discussion is made on the pay‐off vector, which minimizes in the lexicographical order the complaint differences, taking the characteristics of the coalitions into consideration. Then as a method which can solve the formulated linear programming problem with less computational burden, an algorithm involving the relaxation method is proposed. A computer program was constructed and is applied to the cooperative water resource development program.
Steady state analysis of oscillatory circuits with harmonic components by volterra series
Authors: Ichikawa Satoshi , Shyakuda Yukio 
Published: July 2007

AbstractChua and Tang reported a method based on the Volterra series to find the amplitude and frequency of the unknown fundamental wave component of a steady‐state oscillation resembling a sinusoidal wave generated in a self‐starting oscillation circuit. In the present paper, the method is used to find the higher‐order terms so that the harmonic components generated from the term related to the determination of the fundamental component can be found relatively easily. Formulas for the determination of such quantities are derived. Next, this method is used for the analysis of the van der Pol oscillator for which the detailed nature of the solution is available. The validity and the limitation of the application are studied. From the results, it is shown that reasonably accurate solutions can be derived for an oscillation waveform close to a sinusoid as well as a distorted one containing harmonic components. In this method there is no need to derive the differential equation for the oscillator. Insteady, only the algebraic equation found from the circuit diagram must be solved. Finally, this characteristic is used for analysis of an RC phase shift oscillator.
Tracking performance of improved delay‐lock loop
Authors: Hasegawa Takaaki , Nakagawa Masao , Wakabayashi Kunihiko 
Published: July 2007

AbstractA PN (Pseudonoise) code is often used for ranging systems, measurements or clock transmission, etc. Signal transmission using the PN code is effective even at low SNR. The delay‐lock loop is an effective circuit to detect PN code in such large noise, and is used widely. However, in the discriminator characteristic of conventional DLL, the range where the loop control signal can be gained is extremely narrow. Therefore, if the loop once loses lock for noise or for any reason, a large time is required for resynchronization. To compensate the fault of DLL, this paper proposes the improved DLL (IDLL‐1) with extended range of discriminator characteristic. Tracking performances are evaluated theoretically for a first‐order loop, and experimentally for a second‐order loop. Furthermore, the more improved DLL (IDLL‐2), which consists of IDLL‐1 and simple circuits, is proposed. Performance evaluation is done by experiments and simulations.
Recursive ldentification algorithm based on gradient method with application to adaptive bit detector
Authors: Adachi Shu‐Ichi , Sano Akira 
Published: July 2007

AbstractBecause of its rapid convergence the recursive least squares (RLS) method is one of the most popular approaches to adjusting the coefficients of adaptive digital filters. The RLS method is, however, not always effective in practical applications where finite input‐output data are used because it is based on the matrix inversion lemma. The purpose of this paper is to present a new recursive algorithm to obtain the least square estimate of digital filter coefficient parameters on the basis of a finite number of data up to the present by incorporating a gradient approach in solving the normal equation. Although the proposed method is recursive, since it obtains the least square estimate by batch processing of data, it has batch processing merits which are not found in RLS, such as robustness against colored input and noise and smooth convergence to the real value. A method of automatically adjusting the tracking characteristic to time‐variable parameters is described and the effectiveness of this method is examined for the configuration of the FIR adaptive digital filter and the adaptive configuration of the bit detector.
System theoretical consideration on n‐point padé approximation
Authors: Horiguchi Kazumi , Hamada Nozomu 
Published: July 2007

AbstractIn the field of system modelling, circuit synthesis and filter design, it is very important to approximate a given characteristic function by a rational function of an appropriate order. Padé approximation has been known for a long time and is one of the rational function approximation methods used extensively because of its simplicity. This paper proposes to investigate N‐point Padé approximation which is an extension of Padé approximation, from the system‐theoretic viewpoint. The N‐point Padé approximation is a rational function interpolation including the derivative of arbitrary order and, compared to regular Padé approximation and rational Hermite interpolation, it can cope with more diverse demands. In this paper we discuss the following subjects on rational function approximation of given characteristic function: its explicit form, minimal order realization problem, Nuttall's compact form, its relation to continued fractions, and the numerical efficient iterative algorithm. These are more general discussions, even including regular Padé approximation. Also, we give numerical results of the approximation of a transfer function for continuous and discrete systems as an example of application of N‐point Padé approximation.
The volterra series expansion of functionals defined on the finite‐dimensional vector space and its application to saving of computational effort for volterra kernels
Authors: Watanabe Atsushi 
Published: July 2007

AbstractThe Volterra series can be used as a model for a wide range of nonlinear dynamical systems. However, it requires a large amount of computation to determine its kernel from the observation of the input and output of the system. If the input is a white Gaussian signal, the Volterra series can be represented by an expansion using Wiener's orthogonal series of functionals. In that case, numerous methods have already been proposed to reduce the computational complexity utilizing the white gaussian property of the input signal and the orthogonality of the functional series. These methods cannot be applied, however, to the system receiving general input. This paper considers first the space of all functionals defined on the general set of discrete functions, and constructs the set of base functionals spanning that space systematically from the family of linear funtionals with the orthonormal set as the kernels. Then the functional model for the discrete nonlinear system to be measured is determined as a finite‐dimensional approximation in the previously derived functional space. A method is derived to calculate the approximate Volterra kernel. The relation of the proposed method to the multiple correlation function method, which has been used widely as a standard method to determine the kernels, is discussed. Assuming the white gaussian input, the computational complexities are compared, indicacing that the proposed method is far better in reducing the complexity, especially for kernels of higher dimensions.
A consideration on optimum direct detection optical communication receiver
Authors: Hata Masato , Morinaga Norihiko , Namekawa Toshihiko 
Published: July 2007

AbstractThis paper presents an optimum receiver for direct detection/binary intensity modulation optical communication systems. Here, the signal‐plus‐noise model assumes a signal‐dependent nonstationary Gaussian random process. Moreover, assuming white noise and an ideal low‐pass receiver, the receiver vector is generated by sampling of signals and noise. The likelihood ratio for this receive vector is derived based on the maximum likelihood test to determine the structure of optimum receiver. This paper shows that the optimum receiver has both the usual correlation detection for additive noise in the radio wave region and noise energy detection for the signal shot noise. Next, the error rate of this receiver is derived theoretically and its characteristics are evaluated. As a result, the signal shot noise can be effectively utilized for signal detection by allowing a greater bandwidth for the receiver, elucidating treatment of the shot noise from the standpoint of statistical signal detection theory.
General solution for orthogonal periodic real‐number sequences
Authors: Tanada Yoshihiro 
Published: July 2007

AbstractThis paper shows the general solution for the real‐number periodic sequence with an autocorrelation function with zero side lobe, aiming at the application to the spread‐spectrum communication. The general solution is derived by representing the autocorrelation function by a Fourier series and utilizing the components. The solution contains the phase constant. In other words, the sequence and the phase constant are related through the discrete Fourier transform Under the condition that the seqeunce is real, the phase constant is an odd function. However, when the phase constant takes only the value in {O, π}, the phase constant is an even (= odd) function, and the sequence is an even function. From the general solution, it is shown that N sequences obtained by shifting a sequence of order N are orthogonal. An example of the sequence is shown for the case where the phase constant is fixed as φ k E {0, φ }, φk = 2πk3/N (k = 0, 1, ‥, N ‐ l), and for the case where it is continuous as Phiv;1=‐ φ N‐1= θ. The general solution provides a basis for calculating various kinds of pseudonoise sequences.
Successive approximation vector quantization
Authors: Yamada Yoshio , Tazaki Saburo 
Published: July 2007

AbstractThis paper presents a new “ordering” based suboptimal vector quantization, the successive approximation vector quantization (SAVQ). It is found that the SAVQ algorithm can be reduced to the bit arrangement mapping from vector to scalar followed by the scalar quantization. Therefore the SAVQ requires no calculation of distortion. However, the tree search vector quantization (TSVQ), another suboptimal VQ, does require calculation of distortion. This allows the real time vector quantizer to be implemented with significantly less hardware complexity than TSVQ. For the source with exponential density, the simulation results demonstrate that SAVQ provides the mean‐squared‐error equal to or less than that obtained by TSVQ.
A consideration for measure of information based on the dempster‐shafer theory
Authors: Kobayashi Kunikatsu , Suzuki Nobuaki , Nemoto Yoshiaki , Sato Risaburo 
Published: July 2007

AbstractThis paper discusses the measure of information for the event using the probability theory by Dempster and Shafer. By providing various kinds of information to the event containing an ambiguity, the ambiguity is gradually decreased to define the event in a clearer way. The combination rule by Dempster is most suited to represent the combination of information. This paper shows first that several representations can be made for Dempster's combination rule. Then using the upper and lower probabilities defined by the basic probability of the event, the upper and lower information measures are defined, followed by the discussion of their properties. The lower probability of a set (event) is defined as the sum of basic probabilities of all subsets in the set, and the upper probability is defined as the sum of basic probabilities of all sets which contain an element of the set. Thus, the upper and lower information measures can be interpreted as the measures of information concerning the message with ambiguity. Finally, several examples are discussed, determining the information measure for the message containing ambiguity.
A/D and D/A converters using a switched capacitor amplifier
Authors: Seki Hideaki , Mori Shinsaku 
Published: July 2007

AbstractWith the development of microcomputers and signal processors in recent years, A/D and D/A converters have increased their importance as analog/digital interfacing circuits. In the past, various types of A/D and D/A converters have been proposed and implemented for practical use. However, they do not necessarily satisfy the requirements for miniaturization, power saving, and low cost. In this paper we have proposed two A/D converters and one D/A converter which utilize the characteristics of a switched capacitor amplifier with switched capacitor bias and load circuits. Their principle, circuit configurations and experimental results are presented. In the proposed A/D and D/A converters only one active element is used. Also the capacitor is much smaller than in the conventional converters. Therefore, the proposed converters are advantageous as an analog/digital interfacing circuit with respect to miniaturization, power saving, and low cost. Experimentally, 5‐bit A/D and D/A converters were built with discrete components and tested. The obtained result confirmed their proper application with a linearity of ± 1/2 LSB.
A charge simulation method with boundary shape taken into account
Authors: Suzuki Yoshihiko , Inoue Yasushi 
Published: July 2007

AbstractThe charge simulation method is used to obtain an approximate solution of the Laplace equation and others but it has several problems including the charge arrangement. This method determines the charge quantitites, the unknown coefficients, by satisfying the boundary values only at the constraint points arranged on the boundary. For a smooth boundary, a small number of charges suffices; however, for a complex boundary the number of constraint points must be increased to represent the boundary shape. The product paper proposes a new charge simulation method with the boundary shape taken into account by utilizing the orthogonal property of the equipotential lines and electric force lines at the constraint points in order to represent a given boundary shape. In other words, the charge quantities are determined such that not only the boundary values but also the forementioned orthogonality are satisfied at the constraint points. It is shown that in this way the boundary shape is taken into account and the error dependence on the charge arrangement as seen in the conventional method can be relaxed.
Suppression of anharmonic spurious modes in quartz resonators by modified electrode design using charge cancellation
Authors: Sekimoto Hitoshi , Ihara Toshiyuki , Nakata Hozumi , Miura Masaaki 
Published: July 2007

AbstractOne of the most important problems in the design of the thickness vibration resonator is how to suppress the anharmonic higher‐order spurious mode which is generated near the main resonant frequency. It is easy to realize a single resonant characteristic by the design based on the trapped energy theory, but the area of the electrode and, consequently, the inductance, are limited. This paper proposes a method which improves this point and increases the degrees of freedom in the design, suppressing the anharmonic spurious mode by adding a mass to the edge of the electrode and by cancelling the charge. In other words, a modified circular electrode structure is proposed in which the peripheral part (ring) of the electrode has a larger thickness. The third overtone resonator is analyzed in detail, and it is shown theoretically that the dominant (3, 3, 1) spurious mode is suppressed by the charge cancellation, thereby realizing a resonator with an essentially single resonant characteristic over a wide frequency range. It is noted that the charge cancellation characteristics for the spurious mode are strongly dependent on the platebacking of the ring electrode. The data for the optimum design are summarized in a table which will be utilized in the future design.