bluuebunny/crossref_metadata_2025 huggingface dataset:
International market entry strategies and performance of United States catalog firms
Authors: Robles Fernando
Published: July 2007

This article analyzes the international market entry strategies of U.S. catalog firms. Market entry strategy was conceptualized in terms of market selection (English- or non-English-speaking country) and mode (exporting, licensing, joint ventures, subsidiaries, and retail stores). The results of a sample of 57 firms active in international markets found that firms entering a culturally close market (English-speaking) were more likely to report greater revenues per catalog and overall performance than those that entered non-English-speaking countries. A cluster analysis of several modes reported by the sample of firms revealed four generic modes. These four generic modes ranged from simple direct exporting to more complex ones that used subsidiaries and retail stores in international markets. Mode of entry was not related to performance. U.S. catalog firms are using a conservative approach to international markets by exporting to countries where the level of uncertainty is low. Firms using this strategy may benefit from lower costs and greater revenues per catalog.
Direct marketing: Passages, definitions, and Déjà vu
Authors: Murrow J.L. , Hyman Michael R.
Published: July 2007

As a prelude to offering a new definition of the term direct marketing, the recent debates on broadening the domain of marketing and broadening the domain of direct marketing are examined and the current definitions of direct marketing are compared. After a new definition of direct marketing is proposed and evaluated, direct marketers are cautioned about the problems concomitant with efforts to redefine direct marketing.
Probability distribution of digital sum variation for bimode pulse transmission code
Authors: Kasai Hiroyuki , Fujii Akira
Published: July 2007

A variety of coding types are proposed to improve the information transmission efficiency for a digital relay and transmission system. Quantitative estimation is required to clarify coding effectiveness with respect to the frequency region of timing waveform sampling characteristics and the time region of intercode interference based on low‐frequency cutoff. Formerly, various calculations were proposed to use the power spectrum for the former purpose and no consideration was given to the latter.

This paper explains how to calculate the probability distribution of digital sum variations to estimate pulse transmission code performance in the time region. Since there are instances where the digital sum variations do not reach a desired state as a result of dc component suppression, the transition probability matrix cannot be determined. The transition probability matrix is then determined by introduction of a new parameter called the state vector, whereby the probability distribution can be calculated. Distribution probabilities for the 4B‐3T code digital sum variation are calculated as a practical application of calculation methods. Error rate performances considering these distributions are shown.

These calculation methods may permit the estimation of pulse transmission code performance in conjunction with the power spectrum formerly used for the estimation of transmission code performance.
Design of a quadrature modulator consisting of gaAs‐FET double‐balanced mixers
Authors: Yamao Yasushi , Suzuki Hiroshi
Published: July 2007

In order to realize a mobile communication system using MSK narrow‐band digital FM modulation, a high‐accuracy and low‐dissipation power IC modulator is needed. In this paper a digital IC double‐balanced mixer, employing a D‐A converter and FET analog switch, is proposed and the design method of a quadrature modulator using this kind of mixer is explained. The spurious level contained in the modulated output signal is analyzed; then the accuracy required of the D‐A converter in order to reduce the spurious level is determined. Next, the relationship is obtained between the upper limit of the carrier frequency of the signal, whose spurious level specification is satisfied by the modulator, and the FET parameters. GaAs FET measurements confirm the analytical results, namely, a quadrature modulator with lower than ‐40 dB spurious level up to about 1 GHz can be achieved.
Numerical analysis of unbounded poisson and helmholtz problem using indefinite element approach
Authors: Kagawa Yukio , Yamabuchi Tatsuo , Kawakami Katsumi
Published: July 2007

In many cases in electrostatic or acoustic field analysis, the infinite region must be considered; this is difficult to handle by the usual finite‐element method. As a means to handle such cases, the region containing sources and complex configurations are considered as the finite region, and the rest as the infinite region. Then, the usual finite‐element method is applied to the finite region, and the infinite region is partitioned into infinite elements. Two types of infinite element have been proposed: by Bettes‐Zienkiewicz and a hybrid type by Pian‐Moriya. The former does not depend on the model, being general in nature, but integration over the infinite region and the determination of the attenuation parameter are required. In contrast, the latter type of infinite element utilizes the general solution of the system equation in the element, which provides a more accurate solution. Furthermore, since the element is of the boundary type, the integration is generally easier than in the former case. The bandwidth of the discrete equation is the same as that of the finite region. This paper considers Poisson and Helmholtz equations and formulates the three‐dimensional parametric element. As computational examples, simple models for the two‐dimensional electrostatic problem, and two‐ and three‐dimensional acoustic radiation problems are considered as computational examples, and the two types of infinite elements are compared and discussed.
Unipole‐slot array antennas
Authors: Ishizone Takayuki , Yokoyama Yukio , Nishimura Shoichi , Mushiake Yasuto
Published: July 2007

One of the self‐complementary antennas is axially symmetric and three‐dimensional. Since this antenna has an axially‐symmetrical antenna, made of a finite‐sized plate, it becomes a hard‐to‐control multibeam antenna. to obtain a single beam we remove one of the unipole arrays from a self‐complementary unipole‐slot array antenna made of two planes intersecting orthogonally. the unipole‐slot array antenna to be studied then becomes a quasi‐self‐complementary antenna. First, we derive analytically that the unipole‐slot antenna has a constant impedance of 2.30 and show that this antenna has a single beam. Next, to develop a broadband high gain antenna, we analyze a unipole‐slot array antenna using a network technique and derive the relation between the gain and the structural parameters of an array antenna with a common scaling ratio. It is shown numerically that this quasi‐self‐complementary antenna maintains a constant impedance characteristic. These theoretical results are confirmed experimentally with an antenna made of finite conductors.
Design of time division switching networks considering amount of control
Authors: Ogino Nagao , Numao Masayuki , Saito Tadao , Inose Hiroshi
Published: July 2007

The amount of network control as well as the traffic efficiency should be considered in designing a network satisfying the overall economy of the switching system. If high‐speed PCM is adopted, T‐S‐T networks are preferable from the traffic efficiency viewpoint. However, S‐T‐S networks can be preferable from the viewpoint of the amount of control. In this paper, a preferable form of S‐T‐S time division networks is derived from the results of the simulation of the network control processes. S‐T‐S type networks are compared with T‐S‐T type networks from the viewpoints of both the traffic efficiency and the amount of control, and it is revealed that S‐T‐S type networks require less control. Finally, a desired network form satisfying the overall economy is clarified in terms of the whole time division networks including both T‐S‐T types and S‐T‐S types.
Numerical analysis of polarization‐maintaining single‐mode optical fibers with circular pits
Authors: Hosono Toshio , Hinata Takashi , Yoshikawa Hiroshi
Published: July 2007

This paper proposes new structures for a polarization‐maintaining optical fiber with axially asymmetric index distribution: (1) a single circular‐pit fiber (SCF), (2) a double circular‐pit fiber (DCF), (3) a non‐coaxial W‐type fiber (NWF). Numerical analyses of their propagation characteristics are based on a new point‐matching method whose computation error is limited only by the mode number truncation error. It is shown that values of β/k0 as large as 3.0 × 10−4 can be obtained with air pits in the SCF and DCF structures.
Bifurcations and chaos in sampled‐data systems with nonlinear elements of C1 class
Authors: Ushio Toshimitsu , Hirai Kazumasa
Published: July 2007

Nonlinear systems contain a phenomenon called bifurcation. In the phenomenon, a small change of the parameter of the system can produce a qualitative change in the system behavior. On the other hand, random behavior in the deterministic system is attracting attention. This behavior is called chaos and is becoming a major problem in engineering. This paper discusses first the bifurcation and chaos in the sampled‐data control system with differentiable nonlinear elements. It is shown theoretically that the fold bifurcation does not occur when the sampling period is changed. Then various kinds of bifurcations are determined analytically for the second‐order system with cubic‐type nonlinear characteristics. It is verified by numerical experiment that the period‐doubling bifurcation can occur. Finally, it is shown that the shape of the strange attractor can change with the sampling period. the result of this study will provide a guide for the determination of the sampling period.
A rerouting scheme for single‐layer printed wiring boards
Authors: Futagami Shin , Shirakawa Isao , Ozaki Hiroshi
Published: July 2007

A rerouting scheme is described, which is incorporated into an existing automatic routing system for single‐layer printed wiring boards and hybrid integrated circuits. This scheme is to strip and reroute portions of the current wire patterns so that not only incomplete from‐tos can be interconnected by means of getting rid of blockages, but those conductor paths so far determined which form unnecessarily long detours can be improved. Several implementation results are also shown.
An analysis of error rates for nyquist‐ and partial response‐ baseband‐filtered digital FM with discriminator detection
Authors: Akaiwa Yoshihiko , Okamoto Eiji
Published: July 2007

It has been known that error rates as well as spectrum performances can be improved by adoption of transit‐ and receive‐baseband filters for digital FM/discriminator detection schemes. the present paper studies these modulation/demodulation schemes with baseband filters for Nyquist (NYQ) and class I, II partial‐response (PR) transmission. Error rates are analyzed theoretically with and without consideration of the intersymbol interference due to a bandpass filter. Two methods are obtained: in the former case, a generally applicable calculation method which requires the assumption of a symbol sequence, and in the latter case, a simpler calculation method than that before.

The calculated results agreed well with the computer simulated results. In comparison with 2, 4 and 8 level NYQ, 3 and 7 level class I PR and 5 level class II PR, higher performance is given by the method in the order of 7 level class I PR, 8 and 4 level NYQ for narrow band transmission.
Focusing deflection by flexible curved solenoid coil
Authors: Kishi Tohru , Takagi Toshinori
Published: July 2007

The so‐called “drift” of a charged particle annexed to the movement along the magnetic flux lines in a curved coil could be compensated by bending the coil in a letter “S” form (S‐type coil) or by superposing vertically the electrostatic fields to the magnetic fields.

For an S‐type coil, when an electron beam accelerated at 2.5 kV was injected into the center of the coil, the focused beam was extracted through the center of the exit plane of the coil. Here, the height of the coil, the horizontal distance between the incident and the exit planes, and the strength of the magnetic fields were 225 mm, 60 mm, and 6.1 × 10−3 T, respectively. In this case, since the exit plane could be moved freely parallel to the incident plane, the focused beam was extracted according to the movement of the exit plane of the coil.

Further, when the electric fields produced by a cylindrical static deflector were superimposed vertically to the magnetic fields in the coil with bending angle 90°, a focused beam without any drift was also obtained from the center of the exit plane.

Therefore, this focusing deflection system will be available to transport the charged beam or to analyze the energy distribution of charged particles.
Cross‐sectional equivalent circuits and transmission characteristics of multilayered helical lines having magnetic core
Authors: Suzuki Mitsunori , Hosono Toshio
Published: July 2007

It is shown that the transmission characteristics of a cable composed of multilayered media and helical conductors can be solved by network analysis as a radial transmission line problem in cross section. the design method has been simplified for lines such as an H‐line and a multilayer helical line that support surface wave modes. For conventional cable structures the equivalent circuit is given independently for the E‐ and H‐modes if the operating frequency is below the short‐wave range. the circuit elements are then represented as lumped constants appropriate to the medium. the two modes are coupled through the helical conductor, represented by a coupling transformer with a transformation ratio determined by the helical pitch. the equivalent circuit can be simplified by the design condition and as a result the relations between the various cable characteristics and the cable structure and material constants are easily seen, thus easing the problem of cable design. With this method, the transmission characteristics of a two‐layer helical line are calculated and the accuracy is evaluated by comparing the results with those of other methods. It is found that use of a magnetic material in the helix core not only increases the delay effect but also reduces the transmission loss and intensifies the external electromagnetic field.
Design of new structural high breakdown voltage V‐MOSFET—Static shield V‐MOSFET
Authors: Katoh Kuniharu , Shimada Yuuki
Published: July 2007

High breakdown voltage V‐MOSFETs are difficult to obtain because of electric field crowding at the bottom of the V‐groove. to overcome this problem, a new structure for a V‐MOSFET is proposed. A design method for reverse blocking voltage and a model for on‐resistance are developed.

The newly fabricated device has a 1.7 times higher breakdown voltage than conventional V‐MOSFETs and the measured and calculated breakdown voltages of the new device are in good agreement. the formula proposed in this paper predicts a 10% increase in onresistance for the new device over that of conventional V‐MOSFETs.
Complex bases and the complex degree of freedom of LCR networks
Authors: Ozawa Takao
Published: July 2007

A complex basis can be defined for a set × of variables such as element currents and voltages (excluding the exciting current and voltage), of a linear lumped‐con‐stant network in the sinusoidal steady state. If a subset Xβ of × is a minimal set that satisfies the condition that any variable in × ‐ Xβ can be expressed as a linear combination of variables in Xβ with constant (not including frequency) coefficients, then Xβ is called a complex basis of X, and the number of variables in, Xβ is called the complex degree of freedom. This paper derives one of the complex bases of the set × of all the element currents and voltages excluding the exciting currents and voltages of the LCR network. Let G be the graph of the network, and consider trees Ti and Tv, together with their cotrees Ki and Kv in G, satisfying the following conditions C1 and C2:

Ti ∩ Kv is a union edge set of current sources and voltage sources;

Under the condition C1, Ti and Tv contain as many capacitors as possible and Ki and Kv contain as many inductors as possible. Let Tsc be a tree of the graph obtained from G by shorting all the edges other than capacitor edges and let K0z be a cotree of the graph obtained by opening all the edges other than inductor edges. Let Ti, Tv ⊇ Tsc and Ki, Kv ⊇ K0z. Then, capacitor voltages of Tv ‐ Tsc, inductor currents of Ki ‐ K0z, capacitor currents of Tv ∩ Ki and inductor voltages and resistor voltages form a complex basis of X.
Generalization of sampling theorem by blurring operation
Authors: Iijima Taizo
Published: July 2007

The sampling theorem established by Someya and Shannon is presntly finding wide applications in various fields. However, it often happens in actual application that the assumption of band‐limitation which is a prerequisite of the theorem is difficult to verify. From such a viewpoint, this paper generalizes the sampling theorem to remedy the problem. the blurring operation originally has the function of positively suppressing the higher‐order harmonic components. It is a regular linear operation for which the inverse operation exists. Utilizing this property and combining the operation with the traditional sampling theorem, a new sampling theorem is derived, by which only those components of the object function in the limited band can be extracted. the generalized sampling function derived first in this paper is a natural extension of the traditional sampling function. With its analytical structure as well as the clearly stated method of computation, the generalized sampling theorem derived in this paper is applicable widely to actual problems.
Topological condition for the nonlinear resistive networks to have a unique solution
Authors: Nishi Tetsuo
Published: July 2007

In a nonlinear resistive network composed of nonlinear resistors, of which the v‐i characteristics can be represented by a strictly monotone increasing function, linear resistors, dc sources and dependent sources, the number of solutions for the network equation depends generally on the network parameters including nonlinear characteristics, resistances, source values, and transmittances of dependent sources. For a certain class of networks, however, the solution is unique for all network parameters. For example, Nielsen and Willson gave the topological necessary and sufficient condition for the network consisting of transistors represented by the Ebers‐Moll model, the nonlinear resistors mentioned above and dc sources to have a unique solution. It is important from a theoretical viewpoint to examine the condition for the uniqueness of the solution for more general types of networks. This paper gives the topological necessary and sufficient condition for the network consisting of nonlinear resistors, linear resistors, dc sources and current‐controlled current sources with transmittance α in the range 0 < α < to have a unique solution for all network parameters.
Pattern synthesis for waveguide slotted array antenna by linear programming
Authors: Hara Yasuhiko , Goto Naohisa
Published: July 2007

This paper discusses pattern synthesis to obtain a fan beam with slot array antennas created on the narrow wall of a waveguide. Traditional pattern synthesis methods of this kind of antenna include the sampling technique of a continuous source distribution over the antenna aperture and the approach in which each slot is treated as a discrete source. In this paper, the locations of slots derived by the sampling method are used as the initial values. the current amplitude and the location of each slot are corrected by linear programming so that the antenna efficiency is improved.

Although the problem of finding the correct amplitude in each slot is a linear problem, that of correcting the slot location is nonlinear. Hence, linear programming is applied to the latter by linear approximation. A successive method is studied in which the amplitude and location of the slot are alternately and repeatedly modified. the antenna efficiency of ‐3 dB has been improved to ‐1 dB. the effect of fabrication inaccuracy on the optimally designed antenna is compared to that based on the traditional design.
Calculation of the allan variances for the rain‐attenuated millimeter wave beacon from a geostationary satellite, and their application to the site‐diversity switching
Authors: Yoshimura Kazuyuki , Shinozuka Takashi , Suzuki Yoshiaki , Mineno Hitoshi , Shimada Masaaki , Kuroiwa Hiroshi
Published: July 2007

We calculated the Allan variance (the frequency stability measure in the time domain) of a rain‐attenuated 34.5 GHz beacon signal transmitted from a geostationary satellite. the obtained results showed that the rain‐attenuated signals basically had random‐process characteristics with fα (α < 0) types of power spectral densities‐typically with α = ‐2, i.e., a random walk process. Also calculated were the Allan variances of bit error rates (BER's) of time division multiple access (TDMA) signals which were attenuated by rain. Occasionally, the measurements showed that the variances were reduced to only a few seconds. We applied these results to sitediversity switching experiments and tried to determine optimum times to measure and compare the BER's of the TDMA signals to be switched (they came from both routes of the main and substations). Simulation experiment results showed that the measuring times to minimize the variances coincided almost with those to minimize switching errors. This was also proved by theoretical analysis.
Dielectric properties and auger electron spectroscopy on anodized thin‐film capacitors of Ta‐AI‐N
Authors: Sasaki Katsutaka , Umezawa Toshiji
Published: July 2007

Thin‐film capacitors have been fabricated by anodization of Ta‐AI film in an atmosphere which includes O to 5% nitrogen without degradation of quality at 300°C. This type of Ta‐AI capacitor has tan δ and temperature coefficient of capacitance (TCC) which are smaller than those of Ta‐AI film without nitrogen even before heat treatment. These values are further decreased after heat treatment in air. to clarify this effect, Auger electron spectroscopy is conducted to find the depth profiles of the elements. It is found that a nonstoichiometric oxygen diffusion layer between the base metal and an anodized layer is reduced by heat treatment.
Extended‐BCH codes using fourier transform over a finite field
Authors: Miyabe Yoshiyuki , Tokiwa Kinichiroh , Kasahara Masao , Namekawa Toshihiko
Published: July 2007

This paper proposes a new construction method of extended codes based on BCH code using a Fourier transform over a finite field. This method applies encoding to a so‐called “tail” which is added for extension and, furthermore, repeats similar encoding to the encoded tail. the constructed codes based on primitive BCH codes generally are excellent in the point of code rate (= number of information symbols/code length) and it is clarified through examples that some of them improve the lower bounds of the maximum code rate. Since the extended codes constructed by this method can generally be considered over an extended field of one degree lower order compared with the shortened codes with the same code length, the number of multiplications needed for syndrome‐calculation in decoding can be reduced to about a fourth. Moreover, it is shown that when the code is constructed by this method, the fast Fourier transform algorithm can be applied to a wider range of code lengths than before in syndrome‐calculation.
Diffraction of an electromagnetic plane wave by a slit in a lossy dielectric slab
Authors: Yoshidomi Kuniaki , Aoki Kazuo , Uchida Kazunori
Published: July 2007

Diffraction problem of an E‐polarized plane wave by a thick slit in a lossy dielectric slab is analyzed. the Fourier transform technique is used to formulate the problem and the Wiener‐Hopf method is utilized to solve it. Our numerical results revealed the following:

maximum values of diffracted fields are not located in the incident direction or in the direction of coherent reflection;

amplitudes of total electric fields behind the slab are not necessarily maximum in the incident direction;

in the case of a thin slab the maximum amplitudes of diffracted fields are proportional to |1 ‐ T| at the back of the slab and to |R| in front, where T is the transmission coefficient and R is the reflection coefficient for an infinitely long slab;

when a slab becomes more lossy, diffracted fields converge asymptotically to some constant values.
Theory of interpolation by M‐times continuously differentiable piecewise‐connected polynomials
Authors: Iijima Taizo
Published: July 2007

Important in practice is the problem of interpolation of a set of sampled values of a continuous function given at equally spaced points. A number of studies is performed. Although the spline function has been talked about recently for an interpolation method by piecewise polynomials, it has a deficiency of unnatural irregularities when applied to video displays. This paper derives theoretically an actual form of piecewise‐interpolation polynomials continuously differentiable M times in the entire range. As the condition for the interpolation functions to maintain natural features, we require: (1) that the effect of the interpolation to each sampled value remains in the finite range; and (2) that the perfect interpolation is accomplished if the shape of the original function is a polynomial of order less than M + 1. the lowest‐order interpolation polynomial satisfying these requirements is found. the interpolation functions found here are in the form of weighted average by way of an individual piecewise‐interpolation polynomial system. This is because such a form is considered convenient for application to theoretical analysis in the picture processing.
Multivariable adaptive iir filtering
Authors: Kikuchi Akira , Omatu Sigeru , Morisue Toshiya , Arimoto Suguru
Published: July 2007

The necessity for adaptive signal processing is recognized widely in applications to communication and control fields. Also, adaptive signal processing for a multivariable system is an important problem. This paper proposes techniques based on gradient consideration for multivariable adaptive IIR filtering, which is constructed from IIR structure having infinite impulse response. the treatment of the gradient shapes the form of the algorithm for adaptive IIR filtering, since the output of the IIR filter is a nonlinear function of the parameter estimates. Thus we consider first a basic algorithm and then construct four adaptive algorithms for multivariable adaptive IIR filtering. to develop a theoretical consideration, we analyze the convergence behaviors of the four proposed algorithms in 1.i.m. sense after proposing new equalities about Kronecker's product. Furthermore, we consider applications of multivariable adaptive IIR filtering to several data processing fields.
Bandwidth design and operating condition adjustment of high‐speed digital optical repeaters
Authors: Hakamada Yoshiro , Suto Koh‐Ichi , Tsuyuki Shigeru
Published: July 2007

Bandwidth design is described for the amplifier and reshaping circuit that determine the receiving sensitivity of a digital optical repeater. Also described is the optimum adjustment of the operating conditions as determined by the combination of the amplification factor of an APD and the discrimination level. For the former, the required conditions are clarified for the clamp circuit as a low‐cut circuit. the relations are obtained between the peak value variation of the output voltage of the clamp circuit and the bandwidth of the reshaping circuit. For operating condition adjustment the repeater operation is formulated under various degradations and the relation between the causes of degradation and the SNR is analyzed. Based on these findings, various adjustment procedures are compared. It is shown that the system has sufficient tolerance to these degradations if adjustment is made for intersymbol interference.

The present study provides a basis for choosing the conditions for the clamp circuit as a low‐cut circuit and the bandwidth for the reshaping circuit. A method of adjusting the operating condition is found that provides sufficient tolerance to degradation of an optical repeater.
Interactive decisionmaking: For multiobjective convex programming problems
Authors: Sakawa Masatoshi
Published: July 2007

This paper presents a new interactive multiobjective decisionmaking technique for multiobjective convex programming problems based on the weighting method. In our interactive scheme, after generating a Pareto optimal solution by the weighting method, the values of the marginal rates of substitution (MRS) assessed by the decision maker (DM) are used to update the weighting vector. As a result, the increased value of the DM's unknown utility function is sought and the local proxy preference function is updated to determine the optimal parameter value involved in the weight updating formula. In this way, the preferred solution of the DM is derived efficiently from among a Pareto optimal solution set by assessing his MRS. Furthermore, considering the imprecise nature of DM's judgments, the MRS of the DM presented in a fuzzy form are interpreted as L‐R fuzzy numbers, and the fuzzy version of the algorithm is also presented. Based on the proposed algorithm, a time‐sharing computer program is written and the interaction processes to solve a numerical example under the hypothetical DM are demonstrated together with the computer outputs.
Analytical method of spiral line
Authors: Nakamura Takashi , Sekine Toshikazu , Yokokawa Senji
Published: July 2007

The spiral line shows promise for miniaturization of circuits because it has the characteristics of a strip line and has a nonlinear structure. However, analysis of this line is difficult because of nonperiodic coupling between the conductors. This paper proposes a theoretical analysis to determine the distributed parameters for a traveling‐wave mode along the line. Theoretical analysis and experimental investigation are performed for the propagation characteristics of the spiral line. the innovative feature of this method is that the series impedance and the parallel admittance due to the primary constants of the line are expressed as integrals of the current distributions. From these expressions the distributed parameters for the forward wave and the backward wave are given in a series form containing complete elliptic integrals. These distributed parameters comprise the relations between the line structure and the frequency and represent the nonperiodic coupling between conductors. Using this method, we obtain the input admittance of the spiral line with its end open or shorted. Since the results agree well with measured data, validity of the method is confirmed. It is also shown that the frequency characteristic of the distributed parameters express that of the input admittance.
A theory of digital picture restoration by using the generalized laplacian—successive elimination method
Authors: Matsuo Moriyuki , Kondo Shozo
Published: July 2007

A digital image is represented by elements of a vector space whose dimensionality equals the number of pixels and linear spatial degradation of a picture is regarded as a linear operator on the vector space. In existing picture restoration theories, especially the theory using a numerical analysis method, this operator is represented by a matrix and the restoration problem is treated as that of obtaining the generalized inverse. In this restoration theory, as the number of pixels increases, the dimensionality of the matrix becomes so large that it becomes very difficult to compute the inverse matrix. In this paper, the generalized Laplacian which is constructed from the linear operator representing degradation is introduced and, by using this operator, the original picture can be restored with high accuracy, simple operations and short computation time. This theory is very effective if the degradation operation is shift‐invariant.
Singularities of green's function in surface integral equations
Authors: Chiba Michitane
Published: July 2007

A 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

Theoretical 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

Theoretical 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

The 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

The 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

This 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

Recently 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

Two 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

This 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

This 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

A 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

With 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

Problems 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

Until 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.