bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adaptive vector quantization of picture signals in discrete cosine transform domain
Authors: Aizawa Kiyoharu , Harashima Hiroshi , Miyakawas Hiroshi 
Published: July 2007

AbstractThis paper proposes the adaptive discrete cosine transform coding with vector quantization (adaptive DCT‐VQ), as a highly efficient coding for the picture signal. In the proposed method, the vector quantization is performed by applying the discrete cosine transform to the picture subblock and partitioning the transformed domain into several vectors. By regarding the transformed domain as more than one vector, the complexity in the coding is reduced. Each vector quantizer is designed according to the standard probability distribution of the cosine transform coefficient, and the universality of the vector quantizer is realized. The mode‐selecting type adaptive control is introduced, to effect the adaptive control of the coding parameters according to the local property of the picture. To cope with the large bit allocation resulting from the adaptive control, each vector quantizer has two‐stage structure thereby reducing the coding complexity. As a result of the performance evaluation by simulation, it was verified that the proposed coding method has a higher performance than the conventional adaptive cosine transform coding and has much less complexity than the vector quantization in the original space domain.
Analysis of a heuristic algorithm for planar assignment problem
Authors: Yamada Shoichiro , Harashima Katsumi , Kasai Tamotsu 
Published: July 2007

AbstractThis paper describes a theoretical analysis of the heuristic algorithm for the efficient solution of (the linear) assignment problem defined on a plane. The evaluation function, or assignment cost, in the assignment problem discussed in this paper is defined as the square‐sum of Euclidean distances between points included in the two point sets. A heuristic assignment algorithm, based on a vertical or horizontal partitioning of the given plane, is presented. Then the average‐case analysis is performed for the algorithm, assuming that the points are distributed uniformly on the unit square plane. Letting the size of the point set be n, the number of partitioned stages in the algorithm be hm and the average assignment cost for n → ∞ be Ǐ, it is seen as a result of analysis that the rate of increase of Ǐ in regard to n decreases monotonously with the increase of hm. It is also seen that when hm is maximum, Ǐ is (1/4) log2. n. The result of theoretical analysis is compared with the result of experiment.
Synthesis of active R allpass networks
Authors: Okine Mitsuo 
Published: July 2007

AbstractMany reports have been made on the synthesis of active R filters which operate in the high‐frequency band using general‐purpose operational amplifiers. Most of these reports were on low‐pass and band‐pass filters. A solution to the problem of obtaining a transfer function whose nominator and denominator polynomials are of the same order as the degree of s similar to other filter functions, that is, high‐pass and allpass filters, still has not been reported. Hence, this paper considers allpass functions which are especially useful in proposing active R networks which are very simple and can be synthesized in an easily designed construction. Three kinds of circuit synthesis methods are presented. Since in networks of this kind, as is well known, the internal signal level generally is higher than the output level, e.g., similar to bandpass filters, it was important to suppress it. Using a concrete example, we show that one of the three kinds of proposed networks is improved considerably with respect to this point compared with other networks. Moreover, we make a detailed concrete examination of networks for (1) the center frequency realizable, (2) the design in the event that GB products of operational amplifiers are all different, (3) influence by the secondary pole on the amplitude and phase characteristics, and (4) the temperature characteristic.
A realization of high‐frequency active RC bandpass filters using voltage followers
Authors: Takagi Shigetaka , Fujiis Nobuo 
Published: July 2007

AbstractUsing voltage followers as active elements in the synthesis of active RC immittances, no impedances could be realized which become zero at dc and no admittances which become infinite with the 2nd order or more at infinite frequencies. A realization method which simulates arbitrary LC filters impedance‐scaled by (1 ρ/s) has been proposed by the authors. This paper presents a realization of high‐frequency active RC bandpass filters simulating impedance‐scaled LC filters by using voltage followers and a passive RC circuit. The frequency characteristics of the simulated filters are damaged mainly by the input capacitances of voltage followers. The effect of the input capacitors is compensated by simulating a circuit consisting of L, C, and ‐R. A transformation of resistively doubly terminated LC bandpass filters is also shown to apply this compensation. Sensitivity analysis and experimental results confirm the effectiveness of the proposed realization method.
Accurate numerical analysis of inductive windows in a rectangular waveguide by singular integral equations
Authors: Matsushima Akira , Itakuras Tokuya 
Published: July 2007

AbstractAccurate numerical techniques using singular integral equations are presented for the scattering problem of electromagnetic waves at discontinuities of waveguides. We take the case of inductive windows made of perfectly conducting strips and derive a set of singular integral equations with the same number of unknowns as the number of windows. In the case of a single window, we extend the quasi‐static analysis in the same way as Lewin's so as to be effective even in the multimode range. Accurate approximate solutions are obtained in closed forms in the frequency range in which at most two modes propagate. For the multiple windows, numerical solutions are obtained by applying Galerkin's procedure directly to a set of singular integral equations because the forementioned analysis becomes increasingly complicated. By this method, we can perform the analysis automatically regardless of the number of windows. Also, unlike the numerical solution using conventional integral equations, relative convergence can be avoided. The error analysis is made by comparing the numerical results with exact solutions and experimental values. As a result, it is proved that the accurate solutions are obtained by these methods even if small‐sized simultaneous linear equations are solved.
Radius and diameter with respect to edges in a nondirected graph, and upper and lower bounds for the diameter
Authors: Sengoku Masakazu , Kobayashi Kazuhito , Shinoda Shoji 
Published: July 2007

AbstractThe radius and diameter of an undirected graph G are well known as basic concepts of graphs. It is known that an inequality r(G) ≤ 2r(G) holds for the radius r(G) and diameter d(G). This exhibits the upper and lower bounds for the diameter, and these bounds are known to be optimal. The radius and diameter of graphs are the quantities defined by the distance between vertices. On the other hand, edges are also important elements as well as vertices in graphs. However, the radius and diameter with respect to edges have not been considered very much. This paper proposes an idea concerning the radius and diameter of graphs defined with respect to edges. In other words, a quantity is defined corresponding to the distance between edges by the minimum length of a tieset containing the two edges simultaneously. Then it is shown that the quantity is a quasi‐distance satisfying the triangular inequalities. Concepts of the radius and diameter are introduced as well as in the case of vertices. Further, an inequality revealing the upper and lower bounds with respect to edges is derived and it is shown that the upper and lower bounds are optimal. Finally, it is described that similar results are obtained concerning the upper and lower bounds of the diameter when the quasi‐distance between edges is defined using cutsets.
Optimized equivalent‐weight budget design of communication satellite in multibeam mobile satellite communication system
Authors: Hagiwara Eiji , Yasuda Yoshiyuki , Mishima Hiraku 
Published: July 2007

AbstractOptimization of system design parameters, such as onboard antenna diameter, number of beams, and number of onboard transponders, is of great importance to decide system capacity of subscribers in a multi‐beam mobile satellite communication system.This paper describes an optimization method of important system design parameters to maximize system capacity of subscribers under limited weight budget and dissipation power of satellite mission and limited service area.First, the concept of aquivalent weight, which is defined by a linear combination of weight and dissipation power of satellite mission is proposed. Next, the optimization of above design parameters, giving the maximum system capacity of subscribers, is made under the constant equivalent weight of the total satellite mission.As a result, it is found that the optimized conditions are simply expressed and universal.
Computational accuracy in determining the sign of an algebraic quantity
Authors: Yoshida Kiyonori 
Published: July 2007

AbstractThis paper considers the computational accuracy when performing a numerical computation of an algebraic quantity to determine the sign. For an algebraic function α({di}) of data {di} we introduce the (n, m, l) degree to discuss a method for its estimation. It is shown that when data {di} are given in fixed decimal point form with finite figures, we can correctly determine the sign of the value of α with approximately m times more figures.
Time complexity of gate assignment problem in one‐dimensional array
Authors: Fujii Takashi , Kikuno Tohru , Yoshidas Noriyoshi , Horikawa Hideya 
Published: July 2007

AbstractIn the one‐dimensional array approach, a logic circuit is realized by arranging NAND (NOR) gates in a one‐dimensional array and interconnecting them. The horizontal length of the resultant layout of the logic circuit is determined uniquely by the number of given gates, while the vertical length varies depending on the order of assignment of gates. Thus, to minimize the area required, we must find a one‐dimensional assignment of gates so as to minimize the vertical length. This optimization problem (called problem G) has been formulated as a graph problem and has already been proved to be NP‐hard.In this paper, a restricted problem (called the problem R) is introduced anew wherein a connection of each net is restricted to be between two gates. The problem R plays an important role in developing a heuristic algorithm for the problem G. As for the time complexity, we show that the problem R is also NP‐hard.
Time series analyses of 1/f noise with its unbounded invariant density
Authors: Kohda Tohru , Murao Kenji 
Published: July 2007

AbstractThe time‐series analysis (called indirect method) based on the Perron‐Frobenius operator is well known as a theoretical method which can determine the statistics for various chaos in one‐dimensional distance dynamical systems without determining the trajectory. However, it is rare that a strict solution for the statistic can be determined explicitly and consequently, the indirect method is not practical at present. To remedy this situation, previously we proposed an indirect method based on Galerkin's approximation to the operator, and verified its usefulness. However, the method was not effective for the intermittent chaos with 1/f power spectrum. This paper extends the indirect method using Galerkin's method by introducing the singular function in the approximation to the unbounded invariant density. As a result, the power spectrum is obtained which agrees fairly well with the data calculated directly from the trajectory over a wide frequency range. An interesting result was obtained by the recent study wherein the spectrum of the intermittent chaos has the form of 1/fδ in the limit of zero frequency, where the exponent δ is related explicitly to the nonlinearity of the one‐dimensional discrete dynamical system. However, the forementioned result refers only to the spectrum of the chaos in the limit. By contrast, the proposed method can serve as a practical method to estimate the power spectrum of 1/f noise over a wide range.
Design of digital signal processing quadrature modulator for digital fm and analog FM signals
Authors: Yamao Yasushi 
Published: July 2007

AbstractIn the field of mobile communication, the transmission of picture and data signals in addition to conventional speech transmission requires modulators that are suitable to both analog and digital FM. In the present paper such a quadrature modulator is proposed which provides stable transmission characteristics by digital signal processing (DSP) techniques. The analysis is mainly aimed at additional noise effects due to the digital generation of analog FM signals.The relations between the sampling frequency used in the D‐A conversion of analog speech signals and the sideband noises accompanying modulation are developed. The relations are given between the number of bits used for quantization in the A‐D conversion and the baseband signal/noise ratio in the case of FM or PM reception of the analog FM wave generated by the proposed modulator.Based on the results of this analysis, a modulator design method providing sufficiently high noise suppression is presented in a flowchart form. The results of measurement of a quadrature modulator realized by the proposed method are shown to agree well with the results of analysis. The agreement demonstrates that the required modulator characteristics can be obtained without tuning.
Data compression and statistical inference
Authors: Amari Shun‐Ichi 
Published: July 2007

AbstractWhen mutually correlated data are observed at two different places, it may happen that data are compressed independently, losing the correlational information as a whole. Such cases are observed frequently in economical and environmental data. When the compressed data (statistics) are combined to perform a statistical inference concerning the probability structure governing the two observations, the loss of the statistical information due to the independent data compression should be noted. In other words, a problem arises of estimating Fisher information lost by the independent data compression in the sense of Shannon information at the two sites. It is another problem to determine the best ways of data compression and estimation. This paper introduced anew the notion of mutual Fisher information, and answers those questions by a new theory, combining the information and the statistical theories. The usefulness of the information geometry, which works on the geometrical structure of the probability space, is also indicated through the discussion.
Accurate analysis of δv/v surface acoustic waveguides on a piezoelectric anisotropic substrate
Authors: Yamada Akira , Shimizu Hiroshi 
Published: July 2007

AbstractThis paper presents an accurate analysis for the Δv/v surface acoustic waveguide, which is generally applicable to the anisotropic substrate. This is a three‐dimensional boundary‐value problem in the anisotropic semiinfinite piezeoelectric medium, and includes a number of difficult points for analysis. There are two contradictory requirements for the analysis: (1) flexibility in the object of analysis; and (2) a simple program for numerical computation and small computational complexity. There has not been presented a method which satisfies both these requirements. The method presented in this paper is highly practical, providing a reasonable compromise between the two. The method is as follows. The boundary condition on the substrate surface of the guide is replaced by an integral equation using Green's function. The resulting equation is converted into a matrix equation by partitioning the boundary into elements for discrete representation. Then the eigenfrequency of the guide is determined by solving the equation numerically. The usefulness of the proposed method is demonstrated by the result of numerical calculation for the dispersion characteristics and the field distribution of the guided mode.
A consideration for the interpolation problem with first‐and second‐order information
Authors: Suzuki Masakiyo , Nagai Nobuo , Miki Nobuhiro 
Published: July 2007

AbstractA wave digital filter (WDF) is a low‐sensitivity digital filter which simulates lossless analog circuits. A lattice‐type digital filter (AR lattice filter), which is used in digital signal processing, is a WDF equivalent to a cascade of unit elements (u.e.). As the generalization of this relation, a WDF realizing a modeling filter for an ARMA process has been obtained and the network theory with WDF's has been applied to the digital signal processing. The conventional WDF's, except for the AR lattice filter, are constructed by using the transfer functions to be realized. In this paper, unlike the conventional network synthesis, we propose a synthesis method. In this method, a network approximating a modeling filter for a stationary stochastic process is synthesized recursively using a finite number of data of the autocorrelation coefficients (second‐order information) and the impulse response of the modeling filter (first‐order information). A lattice‐type digital filter is derived realizing an approximation of the transfer function. The approximation is one in which first‐ and second‐order information matches the forementioned data. Also, modified least square approximations due to Kalman and Mullis can be realized by this lattice‐type digital filter. This lattice‐type digital filter is a kind of WDF and the relationship between the global stability and the local stability is clear.
Loop antenna with a branch wire for circular polarization
Authors: Nakamura Takashi , Yokokawa Senji 
Published: July 2007

AbstractThis paper reports on the analysis and design of a circularly polarized antenna consisting of a loop antenna with a branch wire of an appropriate length. The idea for developing this antenna derives from the fact that the branch wire has a characteristic as a transmission line coupled with a loop conductor. The present structure is a simple single‐feed antenna operating equivalently as a two‐point feed‐loop antenna. The current distribution in the antenna is decomposed to the balanced and unbalanced modes for which the equivalent circuit and equivalent loop antenna have been derived. The condition for circular polarization has been obtained from the equivalent loop antenna. Based on this condition, a circularly polarized antenna has been designed and various characteristics such as the axial ratio have been obtained. From these characteristics it is found that a structure exists for which the axial ratio can be made much more broadband than other antennas with the length of about one wavelength. The validity of the theory has been confirmed by experiments.
Matrix–fraction descriptions and the Mcmillan form of a transfer function meromorphic in the unit disk
Authors: Inouye Yujiro , Kato Koichi 
Published: July 2007

AbstractThis paper considers discrete‐time systems with matrix‐valued transfer functions, each entry of which is a mermorphic function in the unit disk. Making use of Helmer's result [11], the McMillan form is proposed for a meromorphic transfer function G(z). It is shown that all the numerators of right or left irreducible matrix‐fraction descriptions of G(z) possess the same invariant factors up to multiplication by invertible factors. Also, it is shown that all the denominators possess the same invariant factors except unity invariant factors up to multiplication by invertible factors.
Synthesis of three–dimensional separable–denominator digital filters with minimum roundoff noise
Authors: Hinamoto Takao , Hamanaka Takashi , Maekawa Sadao 
Published: July 2007

AbstractA roundoff noise analysis is presented for three‐dimensional (3‐D) local state‐space digital filters with separable denominator. It is clarified that the output‐noise power and the signal scaling condition are closely related to three, and three positive‐definite matrices, respectively. A procedure is also developed for the synthesis of an optimal 3‐D local state‐space digital filter with separable denominator which minimizes the output‐noise due to roundoff subject to a scaling condition on the state variables. The optimal state‐space realization can be obtained through the 3‐D similarity transformation by individually solving three 1‐D optimization problems.
Characteristics of antenna pattern diversity branches in urban mobile radio
Authors: Ikegami Fumio , Takeuchi Tsutomu , Yoshida Susumu 
Published: July 2007

AbstractThe performance of mobile communication is greatly degraded by the multipath fading which is a large problem in future digital mobile communication. We made a detailed analysis of the urban propagation characteristics and found that use of a directive antenna in a mobile station reduces the fading by the effect of antenna pattern itself. We suggested that excellent diversity branches can be realized by combining more than one directive antenna. This paper discusses first the basic condition for the antenna pattern diversity branches. Correlation characteristics are examined by measurement of 2‐ and 4‐branches. The reduction of the fading is estimated by computer simulation based on the measured data. It is shown as a result that a 4‐branch antenna pattern diversity system has excellent characteristics compared with the space diversity system composed of omnidirectional antennas.
Reduction method of pointing error of El/AZ mount for maritime satellite communications
Authors: Shiokawa Takayasu , Karasawa Yoshio , Yuki Hironori 
Published: July 2007

AbstractDevelopment of small marine antennas has a very important role in the maritime satellite communications with small ships, especially for Japan which has a relatively large number of small fisherboats. As the satellites become larger in size in the future, the shipborne antennas will tend to become smaller. We propose a control method for the antenna mount against ship motions to assure pointing the communication satellite. The two‐axis EL/AZ mount has a light weight and a small size, which gives rise to a large pointing error when the satellite is near the zenith or when the AZ axis is near the control limit for avoiding twisting the cables. We have developed an algorithm to reduce the pointing errors within the pitching amplitudes of the ship. The principle and the experimental results of this system are described.
Propagation characteristics of electromagnetic waves in groove guides
Authors: Yamaguchi Yoshio , Ohtaki Yukio , Abe Takeo 
Published: July 2007

AbstractIn mobile telecommunications in urban areas, a very small zone system within a few kilometers is adopted to meet an increasing demand. Hence, wave propagation must be investigated in such a situation where transmission and receiving antennas are located lower than buildings. Wave propagation has been studied in a groove structure which simulates a road surrounded by tall buildings to geometrical optics approximation. The result was compared to the microwave simulation experiment with dipole and rectangular horn antennas. Theoretical predictions agreed with observations. At higher frequencies, the wave attenuation became smaller, where the wavelength is much smaller than the groove dimensions and the groove or a road works as a waveguide.