bluuebunny/crossref_metadata_2025_split huggingface dataset:
A new transition from rectangular waveguide to image NRD guide
Authors: Hattori Kazuya , Yamamoto Manabu , Itoh Kiyohiko 
Published: August 2002

AbstractThe image NRD guide as a modification of the NRD guide is expected to find applications at millimeter wave frequencies. In order to construct circuits and antennas containing image NRD guides and to evaluate their characteristics, a transition to another waveguide is needed. In this paper, a transition structure from a rectangular waveguide to an image NRD is proposed and its operating principle is explained. Also, by means of numerical calculations based on the effective dielectric constant (EDC) method, a transition intended for use in the R band (30 GHz) is designed. Further, the designed transition is measured and the effectiveness of the proposed transition is demonstrated. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(10): 9–16, 2001
Electromagnetic wave simulation of honeycomb sandwich structures by 3D volume integral equations
Authors: Takahashi Yasuo , Suzuki Shinobu , Matsuda Syuji , Tanaka Kazuo , Tanaka Masahiro 
Published: August 2002

AbstractThe shape of the honeycomb core must be considered in the analysis of the problem of electromagnetic wave scattering in a honeycomb sandwich structure at high frequency. The three‐layer sandwich structure has the characteristic of having a very small dielectric region with respect to its entire volume, since it has a structure in which the upper and lower skin sandwich between them a honeycomb core which contains many honeycomb‐shaped holes. On the other hand, volume integral equations have the advantage of discretizing only the dielectric region, since only the polarized electric current of the dielectric region is an unknown. Thus, electromagnetic wave simulation of the three‐layer honeycomb sandwich structure by using volume integral equations is considered to be an effective means for large‐scale precision analyses. This paper reports a numerical computing method that takes account of the shape of the honeycomb core, applying three‐dimensional volume integral equations to the electromagnetic wave scattering problem of the three‐layer honeycomb sandwich structure, and the results of code verification by means of the optical theorem and its reciprocity are presented. In addition, the effectiveness of the proposed numerical computing method is shown by identifying the effects of the honeycomb core on the electrical field intensity distribution inside the skin. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(10): 24–33, 2001
A theoretical study on suppression of scattering by a perfectly conductive cylinder array
Authors: Aoyagi Takahiro , Nishikata Atsuhiro , Hashimoto Yasuo , Ishino Ken , Shimizu Yasutaka 
Published: August 2002

AbstractIn this paper, TV ghosts produced by the metal suspension cables of a large suspension bridge are studied. Improvement of the D/U ratio at the receiving point is investigated. It is demonstrated by calculations and experiments that by loading the metal cylinders with a cylindrical ferrite, the relative scattering intensity in the 0 to 90° range in the horizontal plane can be reduced. By loading cylindrical dielectric materials the relative scattering intensity can be reduced by about 8 dB, while scattering in other directions increases. Hence, by using a cylindrical absorber made of a combination of a dielectric material and rubber ferrite, suppression of the scattering at more than 90° on one side is investigated. Theoretical calculations of the scattering properties are carried out by means of the multiple multipole program (MMP) method. It is shown that the relative scattering intensity near 120° can be reduced to less than –10 dB without increase of scattering in other directions. It is therefore shown theoretically that the D/U ratio can be improved. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(11): 41–50, 2001
Terahertz‐wave parametric generation characteristics of MgO:LiNbO3
Authors: Ken‐ichi Karino , Jun‐ichi Shikata , Kodo Kawase , Hiromasa Ito , Ietaka Sahashi 
Published: August 2002

AbstractThis paper describes the terahertz‐wave generation characteristics and mechanism of a terahertz‐wave parametric oscillator (TPO) using MgO:LiNbO3, which has high optical damage resistance. We have observed that congruent MgO:LiNbO3 shows fivefold higher THz‐wave output characteristics compared to undoped LiNbO3. To find the optimum concentration of MgO and to study the mechanism of output increase, we measured the THz‐wave parametric generation (TPG) and far‐infrared spectral characteristics of MgO:LiNbO3 samples having different doping concentration. We found that the optimum concentration is 5 mol% and that output is increased due to an increase in parametric gain resulting from the increased Raman scattering cross section and increased lifetime of the lowest A1‐symmetry phonon mode. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 85(4): 22–29, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.1101
Vehicular speed response adaptive antenna
Authors: Hamamura Masanori , Tachikawa Shin'ichi 
Published: August 2002

AbstractWhen an adaptive antenna is used on the downlink receiver side of a moving vehicle, especially in the presence of high‐speed fading, the received signal becomes unsteady and the communications performance is significantly degraded because the updating of the antenna weight is not carried out accurately. In order to resolve this problem, this paper proposes a vehicular speed response adaptive antenna (VSR‐AA). Its performance in a Nakagami–Rice fading environment is evaluated by computer simulation. In order to operate the vehicular speed response VCO, which plays an important role in the proposed VSR‐AA, the angle of arrival of the direct wave must be known. It is shown that the direction can easily be estimated with sufficient accuracy from the maximum gain direction of the characteristic of the adaptively formed beam. By using the proposed VSR‐AA, an improvement of about 10 dB in Eb/N0 at BER = 10−2 can be obtained over the conventional adaptive antenna under the conditions of a Rice factor of 5.0, eight antenna elements, and fDT (product of the maximum Doppler frequency and data symbol length) = 0.05. Further, the BER is substantially degraded in the conventional system as fDT becomes larger. On the other hand, in the proposed system, the BER obtained is almost constant so that a high degree of communications quality is maintained. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 85(8): 11–21, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10004
Design of IIR digital filters with flat passband and equiripple stopband responses
Authors: Zhang Xi , Yoshikawa Toshinori 
Published: August 2002

AbstractIn the design of IIR digital filters, the method that utilizes the classic analog filter design theory to design analog filters and then obtain the corresponding digital filters by s–z transformation is well‐known. However, IIR digital filters obtained via the bilinear s–z transformation have just equal‐order numerator and denominator. Having unequal‐order numerator and denominator will give more degrees of freedom in filter design. In this paper, we consider the design of IIR digital filters with unequal‐order numerator and denominator, and propose a method for designing the flat passband and equiripple stopband filters in z‐domain directly. First, we present a design method of IIR filters with flat stopband and equiripple passband responses. The flat stopband response can be easily obtained only by locating multiple zeros on the specified frequency points, while the equiripple passband response can be designed by using the Remez exchange algorithm and specifying the maximum magnitude error. Second, we can obtain IIR filters with flat passband and equiripple stopband responses via a magnitude transformation such that the passband and stopband become the corresponding stopband and passband, respectively. However, the numerator order of IIR filters obtained by the above method is equal to or higher than the denominator. Finally, we consider the design of IIR filters that have lower‐order numerator than denominator, and present a method for designing the flat passband and equiripple stopband filters directly. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 84(11): 37–44, 2001
A simple quantum computer: Experimental realization of quantum computation algorithms with linear optics
Authors: Takeuchi Shigeki 
Published: August 2002

AbstractIn efforts toward the realization of quantum computers, there have been many proposals to implement controlled NOT gates between quantum bits (qubits). However, the number of quanta in the experimentally realized system has been at most two. Because it is difficult to cope with both the realization of the conditional interaction (e.g., huge nonlinear interaction) between the quanta, and the maintenance of quantum coherence for a sufficient time, the realization of quantum logic gates using several quanta may be difficult in the near future. In this paper, a new method which implements a quantum algorithm using linear optics and single photons is described. This method does not need any huge nonlinearity. Hence, it is practical with today's technology and will be one of the useful physical test beds for the quantum algorithms. The optical implementation of the Deutsch–Jozsa algorithm with a 4‐bit input is proposed, and the mechanism is explained. As one instance of the recent progress of our project, an experiment of single‐photon interference using parametric fluorescence with highly stabilized interferometer system is reported. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 84(11): 52–60, 2001
Chaos communication using unknown input observers
Authors: Inoue Eiji , Ushio Toshimitsu 
Published: August 2002

AbstractChaos synchronization is a phenomenon in which two chaotic subsystems have equal states at each time step. In this paper, a design method is briefly described for unknown input observers used in system theory. Next, a chaos communication method based on design technique that achieves restoration of the information signals by chaos synchronization between a transmitter and a receiver is proposed. Further, with a view to improving the performance of resisting noise, an improved method is proposed by introducing the least‐squares method. The performance of the proposed communication method is tested by simulation. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 84(12): 21–27, 2001
A Fourier coefficient estimation method based on notch filters and an adaptive algorithm for sinusoidal signals in additive noise
Authors: Kudoh Norimasa , Tadokoro Yoshiaki 
Published: August 2002

AbstractEstimating the amplitude and phase of a signal accurately even when the frequencies contained in the signal are already known is very important in many areas. The estimation accuracy and the estimation time are important issues in such areas and a method of improving both of these issues by combining the notch characteristics and the band passing characteristics of serially connected notch filters and an adaptive algorithm is presented in this paper. Computer simulations reveal that the performance of the proposed method is superior to previously proposed methods. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 85(2): 65–73, 2002
Optimal design of diagnosable systems on networks constructed by graph operations
Authors: Araki Toru , Shibata Yukio 
Published: August 2002

AbstractIn this paper, we consider self‐diagnosable systems on computer networks, known as one‐step t‐fault diagnosable systems introduced by Preparata and colleagues. In order to give network topologies, some graph operations such as the Cartesian product, the Kronecker product, and the line digraph operation are utilized. We study the diagnosability of networks constructed by the graph operations based on the idea of “highly structured system,” and then present some optimal networks. © 2002 Scripta Technica, Electron Comm Jpn Pt 3, 85(5): 1–9, 2002
A computational method using genetic algorithms for obtaining Stackelberg solutions to two‐level linear programming problems
Authors: Nishizaki Ichiro , Sakawa Masatoshi , Niwa Keiichi , Kitaguchi Yasuhiro 
Published: August 2002

AbstractStackelberg solutions have been derived for two‐level linear programming problems using genetic algorithms which in recent years have shown their efficacy in optimization problems having discrete variables. Two‐level linear programming problems are converted into single‐level programming problems by including the optimal conditions of lower‐level problems in the conditions of higher‐level problems. The obtained one‐level programming problems become 0–1 mixed programming problems. A computational method for obtaining Stackelberg solutions by generating initial population and using corresponding genetic operators based on the characteristics of the problems by expressing the 0–1 variables as individuals of the genetic algorithms is proposed. The efficacy of the proposed method is shown in computational experiments by comparing it with the variable elimination method. © 2002 Scripta Technica, Electron Comm Jpn Pt 3, 85(6): 55–62, 2002
Optimizing method using frequency annealing: Escape from a local minimum by approximate descent estimation of a low‐pass filter using neighbor data
Authors: Tomikawa Yoshihiro 
Published: August 2002

AbstractThis paper proposes frequency annealing (FA) as an optimization method which searches for the global optimal solution without using the derivative of the objective function. FA detects the global optimal solution efficiently by smoothing the objective function with a low‐pass filter. The gradient of the low‐pass filter, which is defined by a convolution integral, is approximated by the value of the objective function at a finite number of evaluation points defined according to the Gaussian probability density function. Thus, a gradient method without using the derivative of the objective function is realized. The effectiveness of the approximation of the low‐pass filter gradient is verified by the variance analysis of the approximation value. It is shown that by defining the neighbor points with an adequate probability density function, the approximation accuracy is made independent of the dimension M. The usefulness of the approach is demonstrated by a two‐dimensional problem and a simulation of perceptron training. FA can detect the global optimal solution even when the objective function has a local minimum or a discontinuity. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 85(8): 38–50, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1111
The nonstandard FDTD method for three‐dimensional acoustic analysis and its numerical dispersion and stability condition
Authors: Kudo Hironori , Kashiwa Tatsuya , Ohtani Tadao 
Published: August 2002

AbstractRecently, the present authors have applied the FDTD (Finite‐Difference Time‐Domain) method to acoustic problems. FDTD is one of the finite‐difference methods in the time domain used in electromagnetic problems. However, in this method, phase errors cannot be neglected in a large‐scale propagation analysis such as indoor acoustic propagation and they cause problems in the analysis. In order to reduce the phase error, Cole has invented the NS‐FDTD (Non‐Standard FDTD) method for electromagnetic problems. However, the numerical dispersion and stability condition are not described in Cole's paper. Also, the definition is given only for a cubic lattice. In this paper, an application of the three‐dimensional NS‐FDTD method to acoustic problems is attempted. Further, the method is extended to a rectangular lattice. The numerical dispersion and stability condition of the present method are derived. As a result, it is shown that the present method has much higher accuracy than the FDTD method. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 85(9): 15–24, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1115
Measurement of arc properties and spectrum intensity in AC arcs surrounded by plastics
Authors: Ito Hiroyuki , Sakuta Tadahiro , Kobayashi Tadashi 
Published: August 2002

AbstractThis paper describes experimental results on the arc‐quenching properties under the condition of being surrounded by plastic found in low‐voltage circuit breakers. The alternating current used is from 500 to 1100 A(rms) with 60‐Hz frequency. The plastic materials investigated here are polymethylpentene (C3H5), polymethylmethacryl‐ate (C5H8O2), polybutyleneterephthalate (C12H14O4), polycarbonate (C16H18O3), and PTFE (C2F4). In conjunction with the usual arc current and voltage measurements, two images of spectrum intensity of 511 and 522 nm emitted from copper electrode vapor are detected simultaneously by using two bandpass filters. A high‐speed digital video technique (4500 frames per second) is used for analyzing the transient space movement of copper vapor.The arc voltage is strongly influenced by the plastic materials rather than the arc current. Especially in the case of C3H5, the magnitude of the arc current was strongly limited by its high arc voltage. On the other hand, in the case of C2F4, the arc cannot be interrupted and the arc voltage is the lowest value of all. The arcing period is also much influenced by the type of plastic material (the shortest and longest were C3H5 and C2F4, respectively), while it shows almost no change with amplitude of arc current. The spectroscopic images of copper vapor obtained by high‐speed video for transparent plastics of C5H8O2 and C16H18O3 showed that the vapor expanding speed of the former is considerably faster than that of the latter. The results indicate strongly that the arc‐quenching property is affected by the ablation and blast speed of arc‐surrounding plastic materials. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(1): 38–47, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10002
Magnetic circuit design method for magnetic force control systems using inverse magnetostrictive effect: Examination of energy conversion efficiency depending on ΔE effect
Authors: Ueno Toshiyuki , Qiu Jinhao , Tani Junji 
Published: August 2002

AbstractA new magnetic force control method using giant magnetostrictive material (GMM) was proposed and its feasibility was confirmed in earlier studies by the authors. This new method is based on the inverse magnetostrictive effect and the magnetic force is controlled by changing the stress or strain in the magnetostrictive material. This method is expected to have lower heat generation and higher energy conversion efficiency compared to traditional methods, since a constant magnetic force can be maintained by merely applying a constant stress. In this study, the energy conversion efficiency of this method is investigated experimentally using a universal test machine. The input elastic energy was calculated from the stress‐strain loading curve and the converted magnetic energy was estimated from the generated magnetic field. Since the elastic energy is strongly dependent on the history of the strain‐stress loading curve, and the loading curve is affected by the applied magnetic field in the magnetostrictive material, it is important to optimize the bias magnetic field for maximum energy conversion efficiency. The relationships between the elastic modulus and the magnetic field were measured experimentally and the results show that the bias magnetic field must be carefully chosen to obtain high efficiency of energy conversion. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(1): 8–15, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10026
Effective impedance of magnetically insulated transmission lines with geometrical discontinuity
Authors: Hiraoka Kazuki , Nakajima Mitsuo , Shiho Makoto , Horioka Kazuhiko 
Published: August 2002

AbstractSpace‐charge electrons transport a considerable fraction of the current in magnetically insulated transmission lines (MITLs). When an MITL has geometrical discontinuity, the interaction between the disturbed electronics and the nonlinearly coupled electromagnetic field makes their behavior difficult to predict. In this paper, the power flow through such MITLs is discussed by means of a particle simulation code and an analytical model. The results show that the space‐charge electrons tend to maintain the effective impedance of the transmission line by changing the distribution and the boundary of the space charge flow. Although a fraction of the space charge flow shunts the gap when the discontinuity is larger than the critical value, the total current upstream of the discontinuity is still preserved. © 2001 Scripta Technica, Electr Eng Jpn, 135(4): 9–16, 2001
UV laser generation in GdYCOB crystal
Authors: Furuya Hiroyuki , Nakao Hiroshi , Yoshimura Masashi , Mori Yusuke , Sasaki Takatomo 
Published: August 2002

AbstractWe have developed a new rare‐earth calcium oxyborate crystal GdxY1‐xCa4O(BO3)3 (GdYCOB) in order to control birefringence in nonlinear optical crystals. This GdYCOB has been grown by the Czochralski technique. In addition, we have succeeded in generating noncritically phase‐matched (NCPM) second and third harmonics of Nd:YAG laser radiation. We observed two types of photoinduced damage in high‐power third‐harmonic generation (THG). We report the prevention of these kinds of damage by means of an elevated crystal temperature and describe THG performance in the GdYCOB crystal. © 2001 Scripta Technica, Electr Eng Jpn, 136(2): 26–30, 2001
Analysis of ferrite orthogonal core for high‐frequency region based on three‐dimensional nonlinear magnetic circuit
Authors: Ichinokura Osamu , Yoshida Hiroshi , Tajima Katsubumi 
Published: August 2002

AbstractThis paper presents an operating analysis of a ferrite orthogonal core for high‐frequency power control and power conversion. The analysis is based on the three‐dimensional nonlinear magnetic circuit of the orthogonal core, and is called Reluctance Network Analysis. The magnetization characteristics of the ferrite orthogonal core are calculated accurately by using Reluctance Network Analysis. On the basis of the obtained magnetization curves, we can analyze the operating characteristics of the various application circuits of the orthogonal core. For an example, the control characteristics of a high‐frequency variable inductor using the ferrite orthogonal core are calculated in this paper. © 2001 Scripta Technica, Electr Eng Jpn, 137(4): 10–17, 2001
Application of time‐frequency analysis for EMC study of a power conversion system
Authors: Akamatsu Keiji , Michihira Masakazu , Funaki Tsuyoshi , Kawasaki Zenichiro , Matsuura Kenji 
Published: August 2002

AbstractIn recent years, the harmonics and EMI noise sent out from an electric power conversion system have attracted a great deal of attention in electromagnetic environment problems, so that the above considerations have become important. Therefore, there is a need for a detailed frequency analysis, for example, of transient phenomena during switching. We thus have proposed an analytic technique using the wavelet transform, in which it is possible to detect a phenomenon in terms of both time and frequency. In this paper, we perform an analysis using a wavelet transform on actual measured data at the switching interval. Then, based on the results obtained, we demonstrate the high validity of the wavelet transform and its application to the field of power electronics. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(1): 48–56, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.1170