bluuebunny/crossref_metadata_2025_split huggingface dataset:
Singularities of green's function in surface integral equations
Authors: Chiba Michitane 
Published: July 2007

AbstractA method based on the integral equation defined on the boundary of an object often is used to analyze numerically scattering or antenna problems. However, depending on the boundary condition or body shape, a surface integral is required which includes the second‐order derivative of Green's function. In general, this integral diverges due to the singularity of Green's function. However, its finite portion converges. When the finite portion of a diverging integral is evaluated numerically, processing of the singularity cannot be treated accurately in numerical calculation. A method is presented here in which the finite portion of the diverging integral is evaluated analytically in a finite region and only the nondiverging portion is evaluated numerically. A formulation is presented in which the singularity of the second derivative of Green's function is removed. the present method is applied to examples of two‐dimensional problems. As an example of three‐dimensional problems, the method is applied to a cylindrical antenna. In the latter case, the equation for the electric field becomes extremely simple and Galerkin's method can be applied if piecewise sinusoidal functions are used as the expansion functions. It is shown by means of numerical examples that extremely thin as well as thick antennas can be analyzed.
Characteristics of a 4, 5 and 6 Ghz bands oversize circular bending waveguide
Authors: Yamada Yoshihide , Nakajima Nobuo , Huruno Takayoshi , Abe Kohshi 
Published: July 2007

AbstractTheoretical investigations and results of a trial test on the oversized circular waveguide bend for the 4, 5, and 6 GHz bands are reported. Degradation of cross polarization isolation in the waveguide bend is shown to be caused not only by the distortion of the guide diameter but also by the higher‐order modes generated at the bend. In theory, degradation can be improved by connecting an elliptical waveguide with a rotating flange to the bent waveguide and rotating it by a given angle. We show the range of the rotating angle of the elliptical waveguide in which cross polarization isolation is improved. Measured electrical characteristics of the circular waveguide bend made for trial are compared with computed values and the analytical method is proven to be effective. It is found that the circular waveguide bend can be used in practice if it is combined with an elliptical waveguide with a rotating flange and TM mode filter.
Continuously tunable energy transfer laser operation in four‐dye mixture systems
Authors: Muto Shinzo , Ito Chiaki , Inaba Humio 
Published: July 2007

AbstractTheoretical as well as experimental investigation of the energy transfer dye laser (ETDL) operation has been performed, aimed at development of a dye laser which covers a wide wavelength range without exchanging a dye mixture. the following two dye mixtures are shown to be very effective: Rhodamine 6(R6G)‐Safrain.T(ST)‐Cresyl Violet (CV)‐Nile Blue(NB) and Coumarin 1(C1)‐ Acriflavine(A)‐Uranine(U)‐R6G. Their desirable dye concentrations are derived and the tuning characteristics are measured. Conclusively, a continuous tuning was achieved over 130 nm in either case, and hence almost the entire visible range is covered with these two ETDL's.
Topological formulas for switched capacitor networks
Authors: Kaneko Mineo , Kunieda Hiroaki , Onoda Mahoki 
Published: July 2007

AbstractThe two‐phase switched capacitor (SC) network containing nullators and norators as active elements has two different network structures between which it alternates periodically, Since the current and voltage graphs can be defined for each of those, the network behavior is based on four graphs. This paper considers such SC network and derives topological formulas for z‐domain network functions. SC common trees are defined first for the above pairs of current and voltage graphs, and it is shown that the denominator polynomial of the response function is represented by the sum of common‐tree‐admittance products for all SC common trees. Therefore, based on that formula, topological discussions are made on the solvability and the complexity of the network from the graph‐theoretical viewpoint. As a result, the condition for the solvability of the network and the inherent complexity of the network are derived from a topological viewpoint.
Cross‐correlation functions for quadratic‐phase sequences with different periods
Authors: Suehiro Naoki 
Published: July 2007

AbstractThe author has previously proposed new polyphase periodic sequences with autocorrelation sidelobe 0 and minimum cross‐correlation peak value. the periods of the sequences are odd prime N; the number of sequences is N ‐ 1. the sidelobe of the autocorrelation function is 0 and the absolute value peak of the cross‐correlation function for arbitrary two sequences of the same period satisfies the mathematical lower bound 1/√. This paper shows that the crosscorrelation function for these sequences with different periods is 1/√ at every term, where N1 and N2 are the periods of these sequences (Ni is the odd prime, N1 ≠ N2). Thus these sequences of various periods are useful for spread spectrum multiple access system because the number of channels can be increased remarkably by assigning sequences with different periods to the same frequency band.
Spatial‐domain design of weakly causal two‐dimensional recursive digital filters
Authors: Hinamoto Takao , Muneyasu Mitsuji , Mackawa Sadao 
Published: July 2007

AbstractThis paper proposes a technique for designing a large class of two‐dimensional recursive digital filters. A mapping technique is used to design weakly causal digital filters. the design is based upon minimization of the sum of squared differences between the desired and actual two‐dimensional impulse responses over a finite interval. the filter is designed in terms of a canonic form state‐space model. the proposed technique has the advantage of simplicity and is applicable to the design of quarter‐plane digital filters as well as symmetric half‐plane digital filters. the test of stability for such filters is easy.
On digital frequency multipliers constructed with distributed coupled‐line constant‐resistance passive networks
Authors: Sakagami Iwata , Hatori Kozo 
Published: July 2007

AbstractRecently a few studies have been made of distributed coupled‐line type digital frequency multipliers which multiply the repetition frequency of a square input wave. the transfer functions of an n‐section distributed coupled‐line constant‐resistance network and an n‐section distributed‐constant bridged‐T network have the form of a rational function of order n with respect to delay operator z−1. We develop our discussion on the basis of this transfer function. the theory is developed for the coefficients of the rational function and the output response in a stationary state can be determined by the coefficients of both the denominator and numerator. the obtained results can be applied to all networks having the transfer functions treated in this paper, but the detailed realization condition for each individual network is not discussed. the experiments and calculations shown in Figs. 4 ‐ 7 are conducted using the distributed coupled‐line constant‐resistance network as an application example. the network described here can be a digital frequency multiplier for two incident impulse trains, 1111 and 1‐11‐1. the behaviors of the multiplier in the frequency domain as well as in the time domain are investigated and it is shown that a faster impulse train can be obtained at the output in the time domain by adequately thinning out the discrete frequency components of the incident impulse train.
2‐D image‐velocity sensor with a pair of optical fiber arrays
Authors: Hayashi Akihiro , Kitagawa Yoichi 
Published: July 2007

AbstractTwo perpendicular arrays of optical fibers are combined with a spherical lens and cylindrical lenses to form a 2‐dimensional‐velocity sensor. Each fiber array picks up spatial frequency components of the object pattern, and the center frequency of the narrowband output signal gives a velocity component of the object parallel to the optical fiber array. Therefore, velocity of the object is determined from center frequencies of the signals from the two fiber arrays. the equivalent filter including the imaging system is derived and its spatial frequency selectivity and accuracy of the measured velocity are clarified. the accuracy can be set to the desired value by properly adjusting the parameter values describing this system. the validity of the present system has been confirmed experimentally.
Algorithms for plane multicommodity flows
Authors: Matsumoto Kazuhiko , Nishizeki Takao , Saito Nobuji 
Published: July 2007

AbstractThis paper presents a polynomial‐time algorithm which can determine the multicommodity flows in a planar undirected graph G. It is assumed that G remains planar if an edge is added between each source‐sink pair. Given positive and real demand to each source‐sink pair, the algorithm determines whether or not there exists a multicommodity flow in G realizing the specified demand, i.e., feasibility, and if it exists, the multicommodity flow is determined. It is shown that by solving the maximum‐weight matching problem once for a graph which is a modification of the graph dual to the given graph G, the feasibility is determined, and by solving the problem for 0(kn) times, the multicommodity flows are determined. Consequently, if G has n vertices and k source‐sink pairs, the computation time required to determine the feasibility is 0(n2 log n), and the time required to determine the k‐commodity flow is 0(kn3 log n). the memory storage required is 0(kn). It is known that the maximum‐flow min‐cut theorem exists for the case of planar graph considered in this paper.
Characteristics of atmospheric attenuation at 35 GHz obtained by sun tracker measurement
Authors: Shimada Kazuo , Higashiguchi Minoru , Otsu Yuichi 
Published: July 2007

AbstractThis paper discusses the measurement results obtained with regard to atmospheric attenuation at 35 GHz using a sun tracker. the measurements are intended to provide an understanding of the atmospheric aborption attenuation characteristics of millimeter waves on high‐angle propagation paths. We first provide a simple description of the construction and performance of the sun tracker and then discusses the method of measuring atmospheric attenuation by means of solar radio observation. the annual, seasonal and monthly variability of measured atmospheric attenuation at 35 GHz are then clarified based on statistical analysis of measured data covering a period of nearly 5‐1/2 years. Regression analysis is performed on the relationship between the measured atmospheric attenuation and the surface meteorological data. Linear regression expressions are derived with respect to the surface vapor levels, and multiple regression equations are derived for the relationship between the surface vapor content and the oxygen content corresponding to the surface meteorological data. Using those equations, a study is made of the estimation precision that can be achieved in estimating atmospheric attenuation from surface meteorological data. Finally, a comparison is made between the measured attenuation and the calculated attenuations using aerological data in the theoretical equations of Bean et al., which are widely used in Japan.
Generalized differential coding theorem and its applications
Authors: Hirosaki Botaro 
Published: July 2007

AbstractA differential coding method regards the transmission line code as a kind of state and assigns the original codeword to each state transition. This method is used widely to regenerate the original codeword as an invariant for the state transition even if there exists state ambiguity during transmission. This paper derives a differential coding theorem as the necessary and sufficient condition for the existence of a differential code on the basis of the mathematical formulation of differential coding problems. According to the theorem, the necessary and sufficient condition for the existence of a differential code is that the set of ambiguity operators should be an irreducible and nonseparable group Gσ, and that a stationary successive operator, which is antihomomorphism on Gσ, should exist. the importance of the theorem is demonstrated through the differential coding for the staggered QAM transmission system, which has been considered difficult to code differentially. Since the theorem is derived under some general conditions, it is applicable to a variety of differential coding problems which may appear in the future.
An algorithm of global routing for gate array LSI
Authors: Harada Ikuo , Tsukiyama Shuji , Shirakawa Isao 
Published: July 2007

AbstractWith the progress of microelectronics technology, the amount of design for a variety of LSI's is increasing rapidly. to make the design and production of such LSI's easier and less costly, a gate array LSI is used extensively.This paper describes a global router for gate array LSI's which is incorporated into our layout system. This router is used to generate for each net an interconnection pattern consisting of channel segments in such a unified way that all interrelated interconnection requirements are taken into account at once. A main objective of the router is not only to minimize the maximum of the local wiring densities, but also to distribute all the interconnection requirements over channels evenly to attain 100% interconnection within a limited area.
A heuristic algorithm for a pin assignment problem of gate array LSI
Authors: Fukui Masahiro , Tsukiyama Shuji , Shirakawa Isao 
Published: July 2007

AbstractProblems occur in an automatic routing for a gate array LSI. These include the logically equivalent terminals to be used for a net to be connected to any one of such terminals, and the vertical track of a feed‐through cell to be used for a net assigned to the feed‐through cell. Since the routing area in such an LSI chip is predetermined, these problems are important in attaining 100% interconnection in each horizonal channel. This paper describes a heuristic algorithm for these problems, and experimental results of the algorithm are also shown to reveal its performance.
Global distribution of atmospheric radio noise
Authors: Kotaki Minoru , Kuriki Isao , Katoh Chuuka 
Published: July 2007

AbstractUntil now, the only global distribution map of atmospheric noise in high‐frequency band was the one published in 1963 by CCIR, based on the observations at 16 sites in the world. However, the map is based on a small number of observation points, and has a problem in accuracy. This paper derives a global distribution map of atmospheric noise based on the global distribution of lightening discharges obtained by satellite. Assuming the average spectrum of the lightning discharge, the map is derived by calculating the ionospheric propagation loss. By this method, the ratio in the atmospheric noise of the component by local lightning can be determined, leading to a better understanding of the atmospheric noise characteristics. By comparing the noise intensity obtained by this method with the value by CCIR and the long‐term observations at various sites in the world, it is seen that the value by the proposed method is closer to the value actually measured than the one by CCIR.
Deflector for a deflection‐modulated EBS amplifier
Authors: Makishima Hideo , Shimokawa Kiyoshi , Mita Nagahisa 
Published: July 2007

AbstractThe deflection‐modulated EBS amplifier operating at microwave frequencies requires a deflector working effectively in the frequency band. the relation between the structure of a meander line and its deflection sensitivity, frequency response, and a new type of the support were investigated; thus a deflector for a 4‐GHz deflection‐modulated EBS amplifier was manufactured. A formula has been derived for the deflection, and it is found that the deflection sensitivity is maximized at a certain ratio of the finger gap to the finger pitch of the meander line. When this ratio is increased, the variation of the deflection sensitivity over a given frequency band is reduced. We proposed a quarter‐wave strip line to support the meander line; it is confirmed experimentally that its quality is almost equivalent to the conventional ceramic spacer.
Nb‐diffused LiTaO3 waveguides and light modulators by use of guided‐to‐radiation mode coupling
Authors: Onodera Hidetoshi , Okuda Masahiro , Awai Ikuo , Nakajima Masamitsu , Ikenoue Jun‐Ichi 
Published: July 2007

AbstractAn analysis and fabrication have been done on a guided‐to‐radiation mode‐coupled light intensity modulator made of a diffused waveguide, and a high modulation efficiency has been achieved. First, it has been shown theoretically that in a waveguide made of Nb‐diffused Z‐cut LiTao3 a modulation efficiency more than 50 dB/cm is obtained at the modulation electric field of 3 V/μm by choosing appropriate amounts of diffusion volume and depth of Nb. Next, before fabrication of the device, a number of waveguides was constructed with the Nb film thickness of 200 – 1000 Å, temperature of 1100 – 1200°c and time period of 3 – 9 hrs. the relation between the diffusion condition and the waveguide parameters were obtained. In the fabricated waveguides, Li2O out‐diffusion exists and an increase of the extraordinary index of refraction is observed. However, by means of a thermal process over 6 hrs at 900°C in LiNbO3 powder, the Li2O out‐ diffusion in the guided layer can be compensated. the modulator has been fabricated with the LiNbO3 powder process and repoling after diffusion for 3 hrs at 1200°C. In a slab‐type modulator with Nb film thickness of 610 Å (electrode spacing of 50 μm and length of 5 mm), the modulation depth was 23 dB at modulation voltage of 250V whereas in a channel structure of width 4 μm and Nb film thickness of 760 Å (electrode spacing of 10 μm and length of 5 mm) it was 19 dB at 70 V.
An extended fisher criterion for feature extraction ‐ Malina's method and its problems
Authors: Okada Toshihiko , Tomita Shingo 
Published: July 2007

AbstractIn the discussion of the two‐class feature extraction problem in pattern recognition, Malina [7] proposed recently a new criterion for overcoming the defects of Fisher's criterion. the discussion in this paper focuses on the effectiveness of Malina's criterion and at the same time points out the problem in his feature extraction method, indicating how to avoid the difficulties. First, no clear definition is made in Malina's method for the coordinate system in the feature space, and the coordinate system used is not optimal. Second, the eigenvalue problem must be solved including the solution of inverse matrix in order to determine the feature axis. For the first problem, this paper points out tha the coordinate axis di and dj in the coordinate system in Malina's method satisfies diTdj = 0, where is the sum of covariance matrices in the class. Then the optimal coordinate system from that viewpoint is given. For the second problem, the inverse matrix is eliminated by performing a certain transformation (A‐1 transformation) to the coordinate system of the original pattern space. the validity of A‐1 transformation is shown by the invariance of the distances among classes, and it is shown that the above optimal coordinate system under A‐1 transformation is the optimal orthogonal coordinate system satisfying diTdj = 0, i j. Finally, Malina's criterion is extended to the multiclass case and the problems are discussed.
Equivalent RC circuit representation of switched‐capacitor networks and its applications
Authors: Hayahara Etsuro 
Published: July 2007

AbstractIn the usual switched‐capacitor filter (SCF), all the switches connected to a node are simultaneously on or off. Thus, every node voltage in the SC circuit changes in synchronization only to in‐phase or out‐phase clock, and has a very simple representation by RC equivalent circuit. This paper derives first the RC equivalent circuits for the basic SC circuits, and presents a method of simulation for active or passive RC circuit using an SC circuit, based on the obtained result. Finally, it is verified by several experiments that the SC circuit constructed by the proposed method operates as the theory predicts.
Analysis of electromagnetic fields in inhomogeneous media by fourier series expansion methods
Authors: Yamasaki Tsuneki , Hinata Takashi , Hosono Toshio 
Published: July 2007

AbstractThis paper presents a new method of analysis with numerical results for planewave scattering by a layer with inhomogeneous permittivity μ(x) and permeability (x). the analysis is based on the following idea: (1) we construct a periodic structure, an iteration of the given layer and apply Maxwell's equation to derive a differential equation for this structure; (2) the electromagnetic fields in this periodic structure are expanded into Fourier series, and the obtained characteristic equation is transformed into an eigenvalue equation; (3) the electromagnetic field in the original inhomogeneous layer is expanded by the solutions of the eigenvalue equation, and the reflected and the transmitted waves are computed by using the boundary conditions. We call this method the Fourier series expansion method (FEM). When the differential equation obtained in the first step of FEM contains dϵp (x)/dx (or dμp(x)/dx), Hill's matrix method cannot be applied for the profile for which d2μp(x)/dx2 (or d2ϵp(x)/dx2) is discontinuous. By contrast, FEM in this paper can be applied even if ϵp(x) (or μp(x) is continuous. dϵp(x)/dx (or dϵp (x)/dx) is discontinuous. Even if ϵ(x) (or μ(x)) of the original inhomogeneous layer is discontinuous we can always construct a periodic structure with continuous ϵ(x) (or μ(x)), so that FEM can be applied. By numerical analysis, the usefulness of the method is evaluated from the viewpoints of the accuracy of the solution vs. the number of terms in the expansion of the comparison with already reported results. As an example of application, reflectivity is computed for the concrete layer with inhomogeneous permittivity and permeability containing magnetic particles.
Design of the pregroove‐shape on an optical disc based on the light diffraction analysis
Authors: Murakami Teruo 
Published: July 2007

AbstractScalar diffraction theory was used in computer simulation analysis of the tracking pregroove fabricated on optical discs: the groove shape relation to the read out (sum) and tracking push‐pull (difference) signals and to detector location; as well as pregroove manufacturing tolerances. As a result it was found that the maximum groove modulation on the sum signal both in the far field and the image plane occurs with a groove phase (depth) of λ/4. In the far field the tracking difference signal is insensitive to changes in groove width and the largest modulation output occurs for a groove phase of λ/8. In the image plane the beam diameter, groove width relation gives 2 points of stable tracking, and modulation is greatest for a phase of λ/4. For rectangular pregrooves, the edge slope has little effect on the readout or tracking signals and difficult control is not necessary. Finally, the formulas for the relationships between the main optical system design parameters (wavelength, beam size, and objective lens numerical aperture) and the groove parameters have been derived in order to generalize the results of the analysis.