bluuebunny/crossref_metadata_2025_split huggingface dataset:
A new variable directional coupler using n‐insb thin films
Authors: Tanaka Ikuo , Isai Masaaki , Ohshitas Masahide 
Published: July 2007

AbstractA microwave directional coupler is reported whose coupling can be varied with externally applied magnetic field without any mechanically moving parts. Variable coupling is achieved by using evaporated n‐type InSb films. A simple, single‐hole coupler is discussed first with regard to its performance, e.g., coupling, variation in coupling, VSWR and insertion loss in mm‐wave region. These quantities are related to the properties of the thin film, in particular, to magnetoresistance of InSb. Second, an improved variable directional coupler using InSb‐Sn‐Ag films, and which has an insertion loss and VSWR less magnetic‐field‐dependent, is introduced and discussed. In the improved coupler, the coupling varies from 19.3 dB to 42.4 dB at 33.8 GHz as the magnetic field is varied from 0 to 10 kGs. The insertion loss and VSWR are 1.18 dB and 1.27, and the directivity is in excess of 19.8 dB. Over the frequency range of 33.8 ± 1.0 GHz, the 2‐hole coupler shows a directivity higher than 14.0 dB, insertion loss lower than 1.23 dB, and VSWR less than 1.33.
Liquid phase epitaxial growth of high resistivity gaas layers by impurity doping
Authors: Kojima Kiyoaki , Hasegawa Hideki 
Published: July 2007

AbstractUsing Fe and Cr, we fabricated high‐resistivity epitaxial GaAs layers. We performed theoretical and experimental studies on the conditions necessary for the growth of high‐resistivity GaAs layers and the electrical behavior of the dopants. Fe doping gives resistivities greater than 104ωcm with good surface homogeneity under moderate growth conditions. We performed theoretical calculations and experiments on the temperature dependence of the resistivity and detected traps using photocapacitance measurements and DLTS. Fe forms a deep acceptor level at 0.47 eV above the valence band in the LPE layers. Cr also gave high resistivities but conditions for growth were much more severe with reduced reproducibility. Cr‐doped layers had a complicated temperature dependence which could not be explained as being due to a single‐Cr deep‐acceptor level.
Analysis of time series signals of wave fields using state vectors
Authors: Aoki Yoshinao , Yamamoto Tsuyoshi , Onda Kunio 
Published: July 2007

AbstractThis paper proposes a method of analysis of time seriesignals of wave fields by state vectors with regard to complex variablez and discrete time variable. The scalar product of these state vectors, the condition of completeness and operators acting on states are defined and basic equations arqderived. The z‐transformation and the convolution theorem are discussed. The present method is applied to the signal analysis by digital filters wherein the signals in the spatial coordinate of wave fields are converted to the time series signals. Two digital filters are introduced to perform Fresnel transform to express the wave propagation in the Fresnel zone. In this analysis, the filter must have characteristics of propagator transform. Further, amethod of reconstructing images as filter outputs is discussed; the hologram signal is converted to the time s eries signals and input to the filter which performs the Fresnel transformation. The result of image reconstruction by this method is compared with the result obtained by the conventional numerical image reconstruction method.
Motion compensated prediction for inter‐frame coding systems
Authors: Ninomiya Yuichi , Ohtsuka Yoshimichi 
Published: July 2007

AbstractAn interframe coding system is most promising when a high coding rate is required. However, it is disadvantageous in that the coding rate for the moving picture is not very high. To eliminate this disadvantage, it is effective to compensate for motion displacement. To do this, we propose a method whereby an image is segmented into many blocks. Each block which contains many motion‐displaced pixels compared with that of the previous frame, is selected. A motion vector is considered as a shift vector contained in correlated blocks which is detected by calculating the correlation between the preceding frame and the current frame for each block. A simple application of this idea to interframe coding requires a vast amount of calculation, and the realization of the above real‐time operation device is difficult. This problem is solved by using a system which modifies sequentially the detected motion displacement in the preceding field, and an experimental device for a motion compensated prediction system is built to test its performance. As a result of an experiment on an actual broadcasted moving image, it has been shown that the amount of the active picture elements of the proposed method has been reduced to about 50 ‐ 60% of that of the simple frame‐to‐frame prediction method, and the average log prediction error has been decreased to about 50%.
A method of calculating transmission signal values for chrominance components in a color imaging system
Authors: Fujio Takashi 
Published: July 2007

AbstractWhen the information of a color imaging system is efficiently stored or transmitted, it is desirable that the image information which is decomposed into three primaries is transformed for transmitting primaries and its signal is processed and transmitted so that it is compatible with the visual and channel properties. In color imaging systems (color TV's), R, G, B, primaries are transformed into a luminance signal and chrominance signal while allocating the bandwidth and the value of the transmission signal to them for broadcasting. In this paper, when the three primary signals to be transmitted consist of a luminance and two chrominance components, we propose a method to quantitatively deal with these transmission signal values, an experiment, and the results of observation. In addition, we describe the results of an examination of how to allocate signal values for multiplexing the primary signals based on the above observation. Also, we examine what property and performance the standard color TV signals possess for various transmission systems. The above discussion is effectively applicable to the selection of the transmission primaries or the form of the transmission system for new color imaging systems of the future.
Start‐up transient responses of a DC‐DC converter
Authors: Nabeshima Takashi , Harada Koosuke 
Published: July 2007

AbstractSmall‐size high‐efficiency DC‐DC converters have been used widely as power sources of various electronic devices. However, because of their large start‐up inrush current and high overshoot of the output voltage, the reliability of the power source and the device is low. In this paper, the generation mechanism of the large inrush current and high overshoot of the output voltage is investigated for the buck‐type DC‐DC converter. It is found that in the converter without feedback circuit, the maximum inrush current is proportional to the product of the switching transistor's ontime ratio and the input voltage. In the converter with the feedback circuit, three types of different operating modes appear depending on the magnitude of the feedback constant. The large inrush current and high overshoot of the output voltage can be suppressed sufficiently by adding a simple integrator to the pulsewidth control circuit.
Decoding of triple and quadruple error‐correcting BCH codes by direct solving of error‐locator polynomials
Authors: Okano Hirokazu 
Published: July 2007

AbstractThe error‐correcting codes have been used extensively to increase the reliability of digital systems in data communication. However, with increasing error‐correcting capability, the complexity of decoders also increases. At present, only one‐bit and two‐bit error‐correcting codes are used. This paper proposes a decoding algorithm for triple and quadruple error‐correcting BCH codes. In decoding the BCH codes, the error‐locator polynomials must be solved by Chien's algorithm. In his method, however, with increasing code length, the decoder becomes complicated and the efficiency deteriorates. In the method proposed in this paper, the fourth‐or lower‐order equations are reduced to the quadratic equation and, therefore, the efficiency is good. This method is also independent of the code length. Its function and efficiency are confirmed by simulation using microcomputer. The present decoding algorithm enables one to realize an efficient decoder with hardware construction using the ROM.
Design of uniform electric field exposure system for biological experiments
Authors: Kobayashi Tetsuo , Matsumoto Goro , Nishiyama Fumihiko , Nakamura Hiroshi 
Published: July 2007

AbstractIn recent years, an interaction between electromagnetic environment and the living body has attracted researchers' attention. The authors have studied the effect of low‐frequency (50, 60 Hz and dc) electric field on the living body and constructed the electric field exposure system. In the conventional exposure system, animals are exposed to electric field between parallel plate electrodes in an insulated cage. However, the electric field inside the cage has not been investigated in detail. In this paper, the electric field intensity and the field uniformity inside the cage are analyzed. Based on the analysis result, a new exposure system is designed. The electric field distribution inside the cage is analyzed by the finite‐difference method. The field uniformity is more than 84%. The measured value agrees with the calculated value. The new system is simple in structure, can readily be constructed and is reliable for a long time.
Shielded TM010dielectric rod resonator
Authors: Kobayashi Yoshio , Kojima Katsuto , Yoshida Shinichiro 
Published: July 2007

AbstractThe resonant characteristics of the shielded TM010dielectric rod resonator are analyzed and its design method is proposed. The resonant frequencies and the no‐load Q value are calculated and their dependence on the specific permittivity and dimension ratio is clarified. Then with a constant ratio of the frequencies of the TM010mode to higher modes, the optimum dimension for the maximum no‐load Q value is determined. The temperature characteristics of the resonator are improved by inserting the conductor to both ends of the rod. The effectiveness of the design method is confirmed by the experiment. The resonator advantages are such that higher modes do not appear in the frequency band over more than one octave, and the no‐load Q‐value is high.
A study on structural identifiability of compartmental systems
Authors: Okano Shigetoshi , Maeda Hajime , Kusuoka Hideo , Kodama Shinzo 
Published: July 2007

AbstractThis paper considers relationships between structural identifiability of compartmental systems and the interconnections of their compartments. First, structural identifiability is defined in such a way that the definition is practically significant and in addition, the interconnection structure of a system well is represented. Then an algebraic condition equivalent to this definition is derived. Based on this, necessary conditions are derived for classes of compartmental systems to be structurally identifiable in terms of interconnection graphs of compartments. A numerical procedure for examining the structural identifiability is given. The results of the application of this procedure to 3‐ and 4‐compartment systems show that the necessary conditions are also sufficient conditions. Finally, several conjectures based on the results of numerical computations are given.
Analysts of anisotropic single‐mode fibers
Authors: Kusano Kiyonobu , Nishida Shigeo 
Published: July 2007

AbstractThe surface wave propagation characteristics of several isotropic single‐mode fibers are analyzed by applying the mode‐coupling theorem to left‐handed and right‐handed circularly polarized waves. In the gyrotropic fiber or unidirectional fiber, both polarized waves become eigenmodes and Faraday rotation occurs at linearly polarized wave incidence due to the difference in propagation constants. The rotation angle in the fiber in which the core and clad have the same anisotropy is identical to the rotation angle of a plane wave propagating in infinite gyrotropic media. The 45° Faraday rotator may be constructed by these fibers with sufficiently practical length.
Polarization properties of optical waves in a twisted elliptical fiber
Authors: Kosano Kiyonobu , Nishida Shigeo 
Published: July 2007

AbstractWhen an isotropic optical fiber is twisted, its permittivity becomes anisotropic. In case of a circular fiber, the polarization plane rotates because propagation constants of left‐handed and right‐handed circularly polarized waves are different. In case of an elliptic fiber, the left‐handed and right‐handed circularly polarized waves couple with each other and its polarization characteristics are complicated. The polarization characteristics of the fiber with small twist can be approximated to those of the elliptical fiber and approach those of the circular fiber as the twist angle increases. The effect of the cross‐sectional deformation on the polarization characteristics may be eliminated by applying a large twist on the fiber. The polarization characteristic curves have 90° periodicity with regard to the incident polarization angle. The circularly polarized wave is generated at some incident polarization angle when the ellipticity and twist angle are optimum. These findings coincide with the experimental results.
Amplication characteristics of injection‐locked oscillator having an opposite phase self‐injection circuit
Authors: Iida Yukio , Morita Masanobu 
Published: July 2007

AbstractThis paper deals with an injection‐looking amplifier with opposite phase self‐injection circuit to which a part of the microwave oscillation output is injected by reflection with proper time delay and opposite phase to the oscillator. The amplifier characteristics are compared with those of the non‐self‐injection case under the oscillator load coupling state which gives maximum amplifier output. First, the optimum delay time of the opposite phase self‐injection circuit for different input and self‐injection conditions is obtained together with the static and phase responses, from which necessary basic data for self‐injection circuit construction are obtained. Next, one of the self‐injection circuits is shown and the characteristics of the amplifier with self‐injection circuit are investigated. Finally, the amplifier is tested and the phase response as a principal characteristic is investigated experimentally. Results show that the amplifier has fast phase response when the comparison is made under maximum output condition.
An interface boundary decision technique in laplace‐poisson domain problems‐a finite element analysis of junction FET
Authors: Kagawa Yukio , Murai Tadakuni , Matsumoto Osamu 
Published: July 2007

AbstractIn treatment of problems of domains governed by either Laplace or Poisson type partial differential equations, such as in field‐effect semiconductor devices, an important problem in practice is the determination of the boundary between the two domains. This paper presents a method using the finite‐element approach to determine the Laplace‐Poisson domain boundary. This method gives the solutions to the shape determination problems with high‐order nonlinearity by adding a modification quantity in applying the sensitivity analysis for given initial boundary shape. Thus, it has the advantages of clear mathematical structure and convenience in applications. As a concrete application example, the two‐dimensional junction FET is taken. Problems involving determination of the depletion layer (Poisson domain) and the current path (Laplace domain) are investigated. Results show that the boundary determination method presented here yields such FET characteristics as the field distribution, substrate effect and the pinch‐off voltage and useful knowledge for design is obtained.
Electron injection parameters and memory characteristics of MNOS devices
Authors: Ohnishi Kazunori , Ushirokawa Akio , Befu Makio 
Published: July 2007

AbstractThe charge injection mechanism of MNOS memory devices is analyzed in terms of the effective electron occupation function fT(t) of N‐O interface traps, and the flat‐band voltage (VFB) shift is derived as a function of pulse voltage and pulsewidth. The N‐O interface trap density NT is determined from the charge injection parameters (vO, r, n). According to the measurement using an automatic VFB measurement device, NT is 1 ‐ 3.6 × 1016 m−2. The parameter vO relating to tunneling in the absence of the applied voltage is dependent on Nss; 3 × 10−9 s−1 for samples with large Nss and 1.4 × 10−12‐1 × 10−18 s−1 for samples with small Nss. The calculated results of the pulse voltage and pulsewidth characteristics using these values agree with the measured results. The present analysis method is applicable for samples with different permittivity, film thickness and fabricating conditions as long as the nitrided film current can be ignored.
A receiver system with a pitch synchronized interpolator
Authors: Murakami Hideo , Irie Kazunari 
Published: July 2007

AbstractIn mobile communications (e.g., vehicular telephony) instantaneous interruption is caused by rapid fading while passing through a downtown area where buildings are dense. The interference caused by this fading markedly deteriorates the quality of communication. To improve the quality of communication, the authors propose a method called pitch synchronized interpolation which interpolates the transient signal by employing the time intervals between speech signals. This paper deals with a receiver system which incorporates this pitch synchronized interpolator. In the pitch synchronized detection or interpolation process of this system, the received speech signal, after undergoing A/D conversion, is fed to a sequential delay memory. This delay memory speech signal is processed by a digital signal processor. Various methods and parameters used here are discussed (e.g., the pitch period detecting method, the frequency of execution of pitch period detection, coding methods, maximum interpolation time, the damping coefficient for damping the interpolation output level to zero when the interruption period exceeds the interpolation time and the design parameters for the speech specimen period). Further, the necessary condition for these parameters are clearly defined. Also, based on the studies of these parameters, a prototype model of pitch synchronized interpolator is designed and fabricated with a reduced pitch period detection cycle of 4 ms and the desired decrease in interruption noise is confirmed.
A method of successive problem decomposition based on an algebraic structure of a problem
Authors: Niizuma Seizaburo 
Published: July 2007

AbstractThe author has recently proposed a method which, given information concerning the relation between the difference of states and the means to be adopted, constructs the quotient problem based on that information and decomposes the given problem into a sequence of subproblems using the solution of the quotient problem. This paper proposes a successive problem decomposition method which, by repeating the decomposition procedures, decomposes the given problem into a sequence of subproblems that is the simplest in the sense that there exists only one difference between the initial state and the goal. A sufficient condition is presented for such a decomposition to be executed. Given a sequence of differences D, the decomposition procedure is represented by an AND/OR sub‐problem tree T(D) and a sufficient condition is sought for T(D) to contain a solvable tree. When T(D) contains a solvable tree, it is possible for the proposed successive problem decomposition to decompose the given problem into a sequence of simplest subproblems.
Trunk division methods in the channel routing style
Authors: Asano Tetsuo 
Published: July 2007

AbstractIn the layout design of building block LSI's wires are placed in the region between a pair of columns of cells. Usually, lines parallel to columns of cells (trunk) and lines perpendicular to them (branch) are placed in different layers and they are connected by throughholes. In the channel routing method we note first that the ordering of trunks is restricted if branches of different nets should not intersect each other. Then we represent this restriction with a digraph called a constraint graph. Using this graph we determine the order of placements of trunks. When there are directed circuits in a constraint graph we must destroy them by partitioning trunks.In this paper we modify the definition of constraint graph so that transformations on a constraint graph due to a partition of trunks become easy. To be more specific, information on terminals also will be incorporated in a constraint graph thereby limiting the extent of a transformation due to a partition of trunks. In addition, the trunk division method proposed earlier is redefined considering multiple divisions; conditions for each partition method to be effective in removing conflicting constraints are examined.
Composition and analysis of a new waveguide resonator filter with dielectric loading
Authors: Fukasawa Atsushi 
Published: July 2007

AbstractThis paper proposes and analyzes a new waveguide resonator filter for comparatively low microwave frequency use. It describes a practical example for its application. The new waveguide structure consists of thin center conductors embedded in cylindrical dielectric rods in contact with conducting parallel plates. This structure can be viewed as a dielectric‐filled coaxial cable provided its external cylindrical conductor extends to a parallel plate. By using the relaxation method calculations are conducted under the assumption of pure TEM fields. The calculated impedance, line coupling, effective dielectric constant and circuit Q are found to be in good agreement with experiment.In order to investigate the higher‐order mode of the filter using this guided structure, the lowest higher‐order is assumed to be the TM01 mode and the effect of the conducting plate is excluded; the wave‐numbers are calculated and compared with experiment. The Q of the 1/4‐wavelength resonator using this guide is higher than that of the dielectric‐filled coaxial line resonator and, without using the interdigital arrangement, couplings between resonators can nonetheless be realized. In the example of the 850‐MHz band filter, it is clear that this waveguide can be used to realize miniaturized, light‐weight, inexpensive and high‐performance filters.
Minimum feedback arc sets of directed star polygons
Authors: Ariyoshi Hiromu , Higashiyama Youichi 
Published: July 2007

AbstractGraph theoretic algorithms often are evaluated by their behaviors on random graphs. This paper attempts to find graphs which can be used to evaluate heuristic algorithms for the minimum feedback are set problem. For these graphs the following properties are required: (i) ease in generating, (ii) their minimum feedback are sets are known. Here we consider directed star polygons (DSP). First, we show that a DSP can be represented by a set of integers (symbols) indicating the number of its vertices and its interconnection structure. Then we discuss transformations of symbols, equivalent symbols, connectivities and a method of obtaining an equivalent class of DSP. Also, we discuss the relationships between symbols of DSP and its feedback are sets. In the case of degree equal to 4, the problem of finding a minimum feedback are set and its density is equivalent to that of finding the maximum number of are disjoint cycles or a symbol the sum of whose elements is the smallest.