bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of time‐varying traffic parameters
Authors: Matsuda Jun , Takemori Eiji , Uedas Tohru 
Published: July 2007

AbstractThe rapid growth of telecommunication networks has brought about diversified applications. This trend will become clearer as these networks become integrated service networks. To control and operate the networks efficiently, necessary actions should be taken to measure traffic flows as precisely and as soon as possible.In general, since actual communication traffic is time‐varying in its parameters, such as the call occurrence rate, requirements are needed for measuring these traffic variations in connection with analysis of traffic‐varying trends, detection of abnormal traffic, traffic prediction, and others. Therefore, this paper investigates an estimation method of time‐varying traffic parameters with the help of a filter. First, we construct a non‐stationary stochastic model of estimated objects and study the estimation accuracy with which the time series data obtained through the stochastic process measurements provide estimates of time‐varying parameters after filter processing. Second, we introduce the optimum filter which minimizes the estimation error, based upon the above analyses. Third, we show some examples of applications, i.e., estimation of varying call occurrence rates and detection of abnormal traffic, both of which are made using the filter.
Two‐dimensional multiple scattering for n slit array
Authors: Hongo Kohei , Furusawa Naoto , Horis Hidehiko 
Published: July 2007

AbstractA new method has been proposed to analyze 2‐dimensional multiple scattering of a plane wave by N parallel cylindrical structures. Diffraction of a plane wave incident on N parallel slits is formulated exactly via Kobayashi‐Nomura's method in an asymptotic form in which the (i+1)‐fold scattering field is given in terms of the i‐fold scattering field. The solution consists of scattering pattern functions for a single slit and their derivatives. The pattern functions are modified when applied to multiple scattering by cylindrical structures of arbitrary cross sections. Numerical solutions are presented for multiple scattering by strips.
A simple numerical derivation of group delay and impulse response from the prescribed characteristic function of a reactance low‐pass filter
Authors: Kida Takuro , Kurogochis Katsumi 
Published: July 2007

AbstractThe numerical integration method is proposed to derive the group delay characteristics and impulse reponse of the reactance low‐pass filter for a given characteristic function of the filter. The approximate values of coefficients in the group delay characteristics τ(ω) are derived from given characteristic function by applying the numerical integration method to the integral formula using Hilbert transform. A simple method is proposed to evaluate the error due to the numerical integration. The coefficient of the transfer function is derived from the coefficient of (ω). Further, the impulse response is calculated from the transfer function by applying the numerical integration method to the integral formula of Laplace inverse transform in which the Bromwitch integral path is replaced by a special path. Finally, the transfer function of the low‐pass filter with sufficiently flat attenuation characteristics in the passband is derived by the minimization method for given group delay characteristics and step response.
Analysis of discrete wave system by optical ray operators
Authors: Aoki Yoshinao 
Published: July 2007

AbstractThe optical ray operators which are used for description and analysis of continuous‐variable wave systems are extended to the discrete‐variable wave systems, and several formulas for discrete wave systems and sampling operators are derived. The discrete wave system relates to diffraction by diffraction gratings. For the discrete wave systems with periodicity in case of a finite number of sampled values, the condition of completeness is derived in relation to the discrete Fourier transform. The result of the analysis is applied to the discussion of the recursive convolution and the derivation of the convolution theorem. The ray operators are applied further to two types of Fresnel transforms to describe wave propagation. The ray operators are also used for analysis of super‐resolution in the presence of both continuous and discrete wave systems.
QPSK modem system for tdma satellite communications
Authors: Fujino Tadashi , Umedas Yoshiaki 
Published: July 2007

AbstractFor the design of the QPSK‐TDMA satellite communication system, analyses and experiments of modem systems have been made. When the burst‐mode QPSK signals with white Gaussian noise are input into the demodulation system, the demodulation system including the carrier recovery circuit, is influenced by noise. In this paper, the symbol error rate in the CPSK transmission, the code error rate in the DCPSK transmission, the unique word error rate (UWER) [for PSK transmission for both C and DC] which is important for the frame timing synchronization signal extraction, and occurrence probability of cycle slip in CR as well as its effect on the UWER, have been analyzed. Furthermore, experiments have been made and their results have been compared with the results of the analyses. Also, it has been shown by examples that the modem system of the QPSK‐TDMA system can easily be designed by using the results of the analyses.
A design method for hairpin line circuits
Authors: Nakano Yoshihisa , Ikedas Tetsuo 
Published: July 2007

AbstractThe hairpin line circuit is one of the distributed coupling lines with special terminal conditions, and various design methods have been reported. However, because of the complexity in dealing with the terminal conditions, equivalent circuits for the hairpin line circuit are not easily derived unlike interdigital circuits. It is desired to establish a simple design method instead of using approximate theory from admittance matrices. In this paper, the equivalent circuit is derived from multiport admittance matrices with the terminal conditions taken into account and its properties are clarified. From these results, the design method is developed under given circuit specification. In this method, the circuit analysis and design are made by matrix calculation and are suitable for computer calculation.
Design theory and characteristics of solid‐state mutual coupling cable
Authors: Matsuda Shizuo 
Published: July 2007

AbstractPreviously, the author reported the theory of the solid‐state mutual coupling cable (hereafter, called SSMCC) which utilizes active coupling among three conductors to compensate the cable losses. In this paper, the optimum design theory of the SSMCC is presented with consideration of the realization condition. The design procedure is described for given transistor characteristics and cable conductor resistances. The design example of an experimental SSMCC and its transfer characteristics are presented. The SSMCC is lossless at the lossless frequency in the transmission band and has almost identical loss at frequencies above and below this lossless frequency. In the analysis, the conductor skin effect is ignored.
A design method of broadband polarizers using metal posts
Authors: Ishida Osami , Kaniya Shojiro , Takedas Fumio 
Published: July 2007

AbstractA broadband polarizer with metal posts is designed on the basis of the fact that normalized capacitive susceptance of short posts decreases at high frequencies. To obtain the design data, the measurement is made for the optimum post diameter and its length which give negative normalized capacitive susceptance, and the magnitude of the post susceptance for the orthogonal two polarized waves. A method of determining the post size for a broadband polarizer is examined from the equivalent circuit. To obtain good VSWR characteristics, the post susceptance in the matching sections follows the raised cosine distribution. The relation between the number of posts and VSWR is clarified. An experimental polarizer has an ellipticity less than 0.25 dB in the specific broadband 12.6%.
Time domain analysis of networks containing lossless transmission lines via improved Gear's algorithm
Authors: Kishino Takumi , Hamada Nozomu 
Published: July 2007

AbstractThis paper considers time domain analysis of electrical networks consisting of lumped elements and lossless transmission lines. In this circuit analysis algorithm. Branin's equivalent circuit representation for lossless transmission line leads to an efficient algorithm for computer‐aided transient analysis.In this paper, we point out some problems and propose the improvements for Gear's algorithm applied to the transient analysis of networks containing transmission lines. The improvements are made on the setting of time step size and the interpolation techniques. The proposed rules result in high accuracy and saving of time in the numerical transient analysis.
Fundamental consideration on heterogeneous packet switching involving message communications application
Authors: Yoshida Yutaka , Takenaka Toyofumi , Watanabe Naoya , Tsukadas Keiichi 
Published: July 2007

AbstractRecently, the packet switching network which deals with relatively short data packets has been developed for the conversation‐type communication between the periphery and computer. However, in the message communication in which files and picture information are exchanged, the packet switching network must deal with long packets. The packet switching network which deals with long and short packets is called the heterogeneous packet switching network. In this paper, the optimum packet size for the message communication is discussed from the viewpoint of communication cost. Further, the segregated‐type and integrated‐type heterogeneous packet switching systems, the buffer memory and packet transfer delay time, are evaluated and compared.
Application of error‐correcting codes to the DCPSK system
Authors: Nakano Yukio , Kasahara Masao , Namekawa Toshihiko 
Published: July 2007

AbstractThe application of error‐correcting codes to the DCPSK system is discussed. Nakamura and Iijima have proposed a method in which the block code to be applied inside the differential coding is applied outside the differential coding. The method of Nakamura and Iijima is first investigated in detail from the viewpoint of coding theory. Based on the results it is shown that a paired error‐correcting code can be constructed in the block code from the random error‐correcting code by a linear transformation. Then, applying this to the convolution code, a method is devised for constructing the generating matrix for the paired error‐correcting code by carrying out a linear transformation of the generating matrix for the random error‐correcting code with differential coding. Search for a convolution code to be used in the DCPSK system is made on a computer. Finally, a code is constructed which can successfully correct the error caused by reference phase slip in synchronous detection as well as by random error in the channel. The usefulness of the code in the DCPSK system is demonstrated.
On code conversion by constant‐resistance distributed coupled‐line networks
Authors: Sakagami Iwata , Hatori Kozo 
Published: July 2007

AbstractWhen a unit impulse is incident on a constant‐resistance distributed coupled‐line network consisting of equally long multisection two‐wire coupled lines and a π‐type resistive network, the output response is an infinite pulse train with diminishing amplitudes. With an appropriate choice of element values it is shown that the amplitude ratio of a first few pulses is (1, Om, 1), (1, Om, ‐1), (2, Om, 1, Om, ‐1) and (1, Om, 2, Om, 1) and the remaining pulses become negligibly small. These first few pulses are considered to be signal components with the remaining pulses constituting the characteristic wave distortion. It is possible to reduce this distortion by increasing the number of coupled line sections. In this paper, the distortion rate is defined as the ratio of the characteristic wave distortion power to the signal power. With the total reflected power of the circuit expressed in terms of a complex integral, calculation of the distortion rate is possible. We quantitatively characterize the operational circuit as a symbol converter. Calculations have been made for coupled lines with up to 4 sections. Since the formulation becomes complicated as the number of sections increases, the numerical calculations are made on a computer.
Approximate vector analysis of single‐mode optical fibers with arbitrary refractive index distribution
Authors: Matsuhara Masanori 
Published: July 2007

AbstractThe single‐mode optical fiber, which has stable polarization characteristics, is one of the most important components in the high‐density optical communication system, and R&D interest is focused intensively on this component. This paper presents a vector mode analysis of a fiber with arbitrary refractive index distribution and without axial symmetry, such as an elliptic fiber with arbitrary refractive index distribution, which has been mentioned as one possible optical fiber. An approximate vector solution is proposed. The approximate vector analysis is a practical method of analysis, in that the numerical computation required is that employed in the approximate scalar solution itself, which is simple and obvious, since most of the computation is analytic, and it is possible to determine directly the difference of propagation constants of the two vector modes in the single‐mode optical fiber. The paper discusses the theory, accuracy and application of the approximate vector analysis.
Polarization and transmission characteristics of a symmetrically‐loaded single‐mode optical fiber and a proposed polarization‐maintaining fiber holder
Authors: Kusano Kiyonobu 
Published: July 2007

AbstractIt is shown that when an external force is impressed on a single‐mode optical fiber to produce an axially symmetrical internal stress there is no coupling between left‐and right‐circularly polarized waves propagating in the fiber. It is also shown that the external force only affects the propagation constant, especially the phase constant, and its effect is equal for each circularly polarized wave. Based on those results the external force is shown to have no effect on the polarization characteristics of the fiber. The reflection for each propagation, mode affected by the external force is discussed, and the effect appears to be negligible. Finally, as a polarization‐maintaining method it is proposed that optical fiber holders that create these stresses be used—such as chuck‐ or shrink‐fit‐types.
Application of plastic substrate for laser beam memory
Authors: Takeshima Mikio , Okada Takeshi 
Published: July 2007

AbstractThis paper reports a technique for making the plastic substrate for a light beam memory that exhibits excellent flatness, an annealing technique for improvement of surface deflection, as well as a projection technique for making good groove patterns. PMMA and PC materials were used for the substrate. These substrates were prepared by two methods: cell cast and injection molding. To improve the surface deflection and heat resistance of the substrate, we tested the press annealing and spin annealing techniques. It is observed that spin annealing is suitable because damage of the tracking groove can be avoided. As far as the thermal reliability and long‐term stability are concerned, PMMA and PC are good candidates for the light beam memory. Tracking grooves were formed on the substrate, using a stamper with the injection technique. Good groove patterns were obtained on both PMMA and PC substrates.
Phase compensation film for planar optical devices
Authors: Shirasaki Masataka , Daido Yoshimasa , Asama Kunihiko 
Published: July 2007

AbstractOptical circuit elements, including isolators, circulators and switches are important components of optical communication systems. Operation voltage and magnetic field of these elements can be reduced by using thin planar type optical crystals for polarization converters. However, in a planar wave guide structure, it is necessary to match the phase velocities of TE and TM modes to prevent the degradation of polarization conversion efficiency. This paper proposes a method to compensate the phase differences by applying optical interference films on the device surface; the optical characteristics of these phase compensation films also are examined. The model assumed herein is a 45° Faraday rotator made with rare‐earth iron garnet (which is magneto‐optical crystal). The phase compensation film is assumed to be a three‐layered structure with silicon dioxide and hydro‐genated amorphous silicon. The wave guide characteristics and polarization conversion characteristics have been analyzed and compared with a single clad layer without phase compensation films. The results show that phase compensation film reduces both the phase difference and the Goos‐Hänschen shift, and effectively reduces cross talk in switches.
A method for kernel separation in the multidimensional discrete fourier transforms
Authors: Morikawa Yoshitaka , Kaneda Masahiro , Hamada Hiroshi 
Published: July 2007

AbstractThis paper presents a general kernel separation algorithm applicable to the multidimensional discrete Fourier transforms (DFT). We first extend the formulation of the 2‐dimensional DFT using the periodic lattice point generation vector system and the sampling lattice point generation vector system proposed by Morikawa et al. to the multidimensional DFT and then show that the kernel separation reduces to diagonalization of integer matrix which connects these two matrix systems. After proposing a diagonalization procedure, we apply it to the DFT of the 2‐ and 3‐dimensional signals sampled on the hexagonal and body‐centered cubic lattices. The procedure permits efficient sampling and increased computational efficiency.
Effects of satellite transponder nonlinearities on spread spectrum satellite communication systems
Authors: Katayama Masaaki , Morinaga Norihiko , Namekawa Toshihiko 
Published: July 2007

AbstractCorrelation analysis using the autocorrelation function is applied to assess the effects of satellite transponder non‐linearities on multiple access SS (spread‐spectrum) signals when SS techniques are applied to satellite communication systems. Both AM/PM conversion and AM/AM conversion nonlinearities are employed in our model (parameters k and L). The model can represent various kinds of nonlinearities by choosing the pair of parameters (k, L) and can discuss the effects of AM/AM and AM/PM conversions on SS signals synthetically and individually. The same analysis is then applied to SCPC (single channel per career) signals for comparison. It is shown that AM/PM conversion degrades the output DUR's of both SS and SCPC systems as severely as does AM/AM conversion. The difference between the characteristics of under linear and nonlinear systems is as large for SS signals as for SCPC signals. Direct sequence SS signals are assumed and the DU (Desire/Undesire) ratio at baseband signal demodulation is adopted as an evaluation criterion.
Determination of optimum structure in coated optical fibers and units
Authors: Ishihara Koushi , Mochizukis Satoshi , Nakatani Nobuo , Uchida Naoya , Fukutomis Hideo 
Published: July 2007

AbstractThe losses of optical fibers may increase during cabling or installation. Such a loss increase may be understood to be due to an exertion of unnecessary external forces on the optical fibers during the above processes because of improper fiber structure. This paper describes the result of the finite element analysis for the stresses applied in cross‐sectional direction upon the core fiber and the unit. It is expected that the degradation of transmission characteristics will be prevented if the stress less than an external force is applied to the fiber cores and unit. As for fiber cores, the 3‐layer cores having buffer layer are considered and then the optimum fiber diameter, buffer layer thickness, etc., are studied. In regards to the unit structure, the test is made for the unit in which a steel wire is located at the center, 6 or 10 core fibers are wound and a binder is applied. Using the above samples, the optimum binder wrapping thickness against the side‐wall pressure and the preferable relation between core fiber diameter and unit diameter are investigated. The core fibers and 6‐core unit are manufactured experimentally and the test is carried out to obtain the relation between the side‐wall pressure and transmission losses. The result shows excellent agreement with theoretical analysis. Thus, we use such a design method to minimize the losses of an optical cable.
A hardware neuron model as a component of the neural network
Authors: Koga Kazutoshi , Hoshimiya Nozomu , Matsuos Tadayuki 
Published: July 2007

AbstractIn the nervous system there are two kinds of information processing: intra‐cellular analog operation and digital transmission between cells. These properties are considered to be indispensable in the construction of a large‐scale parallel information processing system having reasonable redundancy and which incorporates a number of spreading spatial and temporal patterns. As a simplified model having these two processing capabilities we propose a hardware neuron model using a voltage‐controlled oscillator IC. The model characteristics are easily controlled and it can supply a number of models as components of the hardware neural network. The fundamental characteristics for neural operation between multichannel asynchronous inputs are investigated with the model. It is shown that the mean impulse frequencies of the asynchronous inputs are linearly added or subtracted at the model despite the non‐linear property characterized by threshold in the output pulse generation. The characteristics of a backward lateral inhibition connection are also investigated for input pulse sequences. It has an input excitation frequency threshold and shows variable gain or hysteresis characteristics, depending on whether the weighting coefficients of the inhibition inputs are large or small. The model can be connected directly to a microprocessor and can process spatial analog information without an A‐D converter. These characteristics suggest that the model can be used as functional elements in the pre‐processing network of an information processing system for spatial patterns.
Design for nonresonant type microstrip line slot array antenna
Authors: Nakaoka Kaijiro , Shimizu Tadashi , Itohs Kiyohiko 
Published: July 2007

AbstractThere are two versions of the microstrip line slot array antenna: resonant array and nonresonant array according to its termination. Because microstrip loss is much larger than waveguide loss, a design method for the waveguide array is not applicable to the microstrip array. This paper proposes a new design method that utilizes nonlinear optimization and reduces the total loss; it is compared with a conventional design method. Two 2‐array antennas with 64 elements were manufactured with new and old design methods. The antenna designed by a new method showed predicted properties.