bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interactions between dispersion‐managed solitons in optical‐time‐division‐multiplexed systems
Authors: Inoue Takashi , Sugahara Hiroto , Maruta Akihiro , Kodama Yuji 
Published: August 2002

AbstractNonlinear interactions between neighboring pulses in an optical time division multiplexed (OTDM) system may cause timing jitter of the signal pulse, which degrades transmission quality. A dispersion‐managed (DM) soliton is a stable pulse in a DM line and is less influenced by various nonlinear effects than conventional solitons. On the other hand, interactions between DM solitons depend on the strength of the DM line, which is defined as the length of DM period times the variation of the fiber dispersion, and the transmission quality is degraded mainly due to the interactions in a strongly DM line. In this paper, the interactions between DM solitons are studied theoretically and numerically, and we then show that alternating the phases or amplitudes of pulses in the time sequence is effective for reducing the interactions. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(6): 24–29, 2001
Effects of upper‐layer protocols on the self‐similarity of network traffic
Authors: Sumida Yoshiaki , Ohsaki Hiroyuki , Murata Masayuki , Miyahara Hideo 
Published: August 2002

AbstractRecent research has suggested that traffic measured in LANs and WANs is self‐similar. However, no one has clarified why self‐similarity occurs in traffic on networks or how the self‐similarity of traffic affects network performance. In addition, no research has been done on how the self‐similarity of traffic affects the transfer delay or throughput for files, including retransmission processing due to upper‐layer protocols, or on what kinds of effects a user experiences in terms of network performance. Therefore, in this paper the authors clarify through simulations the causes of self‐similarity in the traffic flowing through a network using TCP/IP in the upper layer. In addition, the authors also evaluate how the self‐similarity of traffic affects the packet transfer delay, packet loss probability, and other aspects of network performance. Furthermore, the authors consider how the self‐similarity of traffic impacts on the network performance a user experiences. The results show that the self‐similarity of traffic is affected by the packet loss probability in switches and that the self‐similarity of traffic on a network is preserved when TCP/IP control is used in the upper layer. In addition, the authors show that although average network performance, such as the average transfer delay for files and the effective throughput are not affected much by self‐similarity, the 99.9% transfer delay for files is significantly impacted by self‐similarity. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(7): 19–30, 2001
Optimization approach with edge‐preserving regularization to time domain 1D inverse scattering
Authors: Yoshida Hiromi , Tanaka Toshiyuki , Takenaka Takashi 
Published: August 2002

AbstractThe electromagnetic inverse scattering problems are in general ill‐conditioned, so that image reconstruction becomes unstable when noise exists or when the number of unknown parameters is increased. Usually, regularization is required. However, when regularization is applied, the high‐frequency components in the reconstructed image are suppressed and the reconstruction of the edges becomes difficult. Hence, the concept of edge preservation has been proposed, by which the smoothly varying parts are made smoother and the sharply varying parts sharper. The effectiveness of this concept has been confirmed by analysis in the frequency domain. In this paper, the concept of edge preservation is introduced into the analysis in the time domain. The effect of edge preservation is discussed. As numerical examples, estimation results are presented for the medium constants in a lossless dielectric slab and a lossy dielectric slab. The effectiveness of the method is confirmed. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(10): 1–8, 2001
Stabilization of millimeter‐wave multistage amplifier using amplitude‐and‐phase setting circuits
Authors: Uchida Hiromitsu , Nakahara Kazuhiko , Takeuchi Norio , Matsunaga Makoto , Itoh Yasushi 
Published: August 2002

AbstractThis paper derives the conditions to be satisfied by the amplifier in each stage of a multistage amplifier in order for it to be absolutely stable. It is shown that the stability factor K of each stage need not be larger than unity except for the initial and last stages. By means of this condition, it is possible to improve the gain in comparison to the conventional method in which the amplifiers in all stages are made K > 1 and then are cascaded. In the millimeter wave range, where device performance deteriorates, the gain reduction due to stable design is significant. Therefore, the present conclusion is extremely effective for the design of multistage amplifiers in the millimeter wave range. Further, in this paper, a new design method is presented that assures absolute stability of a multistage amplifier that consists of unit amplifiers, each of which has a stability factor K of less than 1. In this method, an amplitude‐and‐phase setting circuit consisting of transmission lines and resistors is connected at the output of each stage and the transmission amplitude and phase are adjusted in such a way that the stability condition derived in this paper is satisfied. It is shown that there exists an optimum transmission phase maximizing the gain of the multistage amplifier. Finally, the proposed method is applied to the design of a U‐band four‐stage low‐noise amplifier. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(12): 26–36, 2001
Optical near field by vertical cavity surface emitting laser
Authors: Shinada Satoshi , Koyama Fumio , Nishiyama Nobuhiko , Arai Masakazu , Matsutani Akihiro , Goto Kenya , Iga Kenichi 
Published: August 2002

AbstractOur research examines the generation of an optical near field by a vertical cavity surface emitting laser (VCSEL), which can readily be formed into a two‐dimensional array, and the possible application to optical recording capable of high‐speed data transfers due to the higher density and parallel processing achieved when the optical near field is used as the optical head. We propose a VCSEL with metal micro‐aperture for generating the optical near field. Then we demonstrate the ability to create a micro spot size of 100 nm or smaller based on this structure from analysis of the intensity distribution of the micro‐aperture by the two‐dimensional finite element method. We also form a micro‐aperture by using a focused ion beam in a GaAs/AlGaAs VCSEL with an 850‐nm wavelength and perform initial evaluations. In these evaluations, we obtained an emitted power density of 0.12 mW/µm2 from a 400‐nm square micro‐aperture. Furthermore, we observed the light from a 100‐nm square aperture in near field observations and verified the generation of an optical near field by this structure. © 2002 Scripta Technica, Electron Comm Jpn Pt 2, 85(2): 43–53, 2002
Analysis of scattering by means of atomic model: The case of H‐wave
Authors: Hosono Hiroyuki , Hosono Toshio 
Published: August 2002

AbstractA method using the atomic model to analyze the scattering of H‐polarized wave by a cylindrical object of arbitrary cross section shape is described. The differences from the case of the E‐polarized wave are as follows. (1) The number of degrees of freedom of the atomic polarization becomes two so that the number of unknowns is doubled. (2) The method of deriving the atomic polarizations for the case of a conductor is different from that of a dielectric. (3) The method can easily be extended to the three‐dimensional case. (4) In place of the real frequency representation, the complex frequency representation is used. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 85(4): 1–9, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.1099
A method of maintaining the estimation error at a desired level for acoustic echo canceler systems
Authors: Fujii Kensaku , Ohga Juro 
Published: August 2002

AbstractThe estimation error remaining after the coefficients of an adaptive filter have converged are formulated as a function of the power ratio of the noise to the reference signal and the step gain by the normalized least mean‐square (LMS) algorithm. Usually, when applied to an acoustic echo canceler having large fluctuations in the power ratio, updating the coefficients stops when the power ratio exceeds some specified large value. Naturally, however, this stop operation slows the convergence of the coefficients. In this paper, we propose a method that designs a block implementation of the normalized LMS algorithm and can always update the coefficients by adjusting the block length and the step gain. This control method maintains the estimation error at a specific level by matching the power fluctuations of the reference signal, adjusting the block length, and adjusting the step gain to the noise power fluctuations. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 84(7): 41–52, 2001
Modeling of texture images by use of structuring elements of morphological filters
Authors: Komori Takumi , Taguchi Akira 
Published: August 2002

AbstractWe propose a new model of texture images using morphological filters. This method is based on a linear predictive model [autoregressive (AR) model], which is a representative texture image model. This method embeds the frequency characteristics of the texture image in the AR model. In this paper, we will demonstrate a new model that represents the spatial features of a texture image. Morphological filters can remove the spatial features and are used for pattern spectra. In this paper, we consider embedding the spatial features in the structuring elements of morphological filters and propose an Opening Model (OM) to model the convex up features and a Closing Model (CM) to model the convex down features. We examine the reliability of the proposed model and present improvements to the low‐reliability model. Furthermore, our recognition tests clearly show excellent recognition when OM and CM are used together. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 84(7): 53–62, 2001
An error‐control method for narrow‐band subliminal channels: How to embed more bits in a carrier
Authors: Kobara Kazukuni , Imai Hideki 
Published: August 2002

AbstractNarrow‐band subliminal channels, discovered by Simmons, yield the possibility of transmitting covert messages by embedding them in cryptographic digital data, such as (EC)DSA signatures. Embedded messages are used for transmitting important information, or are used as watermarks or imprints of the cryptographic digital data. Anyone can use or abuse these channels very easily since cryptographic digital data which are not subliminal‐free are widely used on the Internet. For example, DSA signatures are not subliminal‐free and they are widely used in various applications, such as PGP and SSH2.A narrow‐band subliminal channel can be considered as a noisy channel when a transmitter generates only a limited number of carriers (a carrier denotes a bunch of data where a covert message is embedded). We propose a way to control the bit‐error property over a narrow‐band subliminal channel, and then evaluate it. In addition, we propose how to reduce the computational cost of generating n carriers as well as a public‐key based narrow‐band subliminal channel. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 84(8): 1–10, 2001
Scalable audio coding based on hierarchical transform coding modules
Authors: Jin Akio , Moriya Takehiro , Iwakami Naoki , Miki Satoshi 
Published: August 2002

AbstractWe propose a method that hierarchically quantizes wideband Modified Discrete Cosine Transform (MDCT) coefficients by developing a module that has a transform coding method primarily for audio as the basic structural unit and freely using this module multiple times at the desired frequencies. The major feature of this method is to implement a simple structure having a high degree of freedom in scalable coding to hierarchically quantize MDCT coefficients over a wide band of frequencies by sharing the proposed module and using it multiple times. This paper presents examples using combinations of the module operating at a sampling frequency of 48 kHz and a bit rate of at least 8 kbit/s. In this example, a bit rate of at least 8 kbit/s and a reconstructed frequency band of at least 4 kHz can be selected as the objective. Subjective evaluation tests are performed to verify the effectiveness of the proposed method. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 84(8): 34–45, 2001
The relationship between the presentation position of a figure and characters on a 3D display and cognitive time
Authors: Shigeta Kazuhiro , Nakayama Minoru , Shimizu Yasutaka 
Published: August 2002

AbstractWhen figures and characters are simultaneously presented in a stereoscopically viewed 3D display, we must check the positions of characters in front of or behind the figure for suitable presentation. We have investigated the relationship between the presentation position of a figure and characters, and the cognitive times for the case where characters are inserted into the figure and for the case where the title is attached with the figure. A rectangular parallelepiped was presented by attaching names to the vertices and its response time was measured by confirming the name of the rearmost vertex. It was shown that in 3D presentation of figures, if characters are presented at a depth that is the same as the part corresponding to the characters in the figure, the response time is shortened and cognition is easier than in the presentation of characters on the depth of the display screen. Next, we presented a 3D geometrical shape and title. To decide whether the contents of the two were in good agreement or not, we measured their response times. We also checked the best position of the title on the figure by subjective evaluation experiments. We found that the best position of the title on the figure has good agreement with the mean depth position of the whole figure. If the title is presented at this position, then the response time is shortened and cognition is easier. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 84(12): 10–20, 2001
3D measurement based on intensity‐phase analysis of intensity modulated moiré
Authors: Lu Cunwei , Yamaguchi Akashi , Inokuchi Seiji 
Published: August 2002

AbstractIn the conventional moiré topography, equicontour patterns can be obtained from one image. Since the problem of determination of the number of fringes remains, unique depth distance cannot be measured and hence automatic measurement is difficult. In the present research, the intensity‐modulated projection light and a transmission coefficient‐modulated observation grating are used to generate an intensity‐modulated moiré in which the intensity of the fringes is related to the depth information of a body. Next, by means of an intensity analysis of the moiré pattern, the order of the fringes is determined and the moiré pattern is divided into several depth regions. Finally, in each depth region the phase analysis is carried out to compute the depth value. Based on this research, a simple apparatus is used for resolving the problem described above and automation of moiré three‐dimensional measurement is realized. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 85(1): 71–80, 2002
Torus window in a torus‐doubling generating circuit
Authors: Miyoshi Tetsuya , Nitanai Takashi , Mikami Noriaki , Inaba Naohiko 
Published: August 2002

AbstractAn extremely significant transition phenomenon from a periodic phase to a chaotic phase is known as torus doubling. In this research, we perform computer simulations to study what kind of periodic behavior exists in the chaotic phase transitioned into due to torus doubling in an electrical circuit that generates torus doubling. The result was the generation of an n‐fold torus that is believed to be deeply related to the period of a relatively large window that appears in the chaotic phase in logistic maps such as a 6‐fold, 5‐fold, or 3‐fold torus in the chaotic phase. In this paper, we call the torus generated in the gap of this chaotic phase the torus window. We also analyze a coupled model consisting of a logistic map and a sine‐circle map as the model to explain the mechanism for generating the torus window. We perform computer simulations to show that the 6‐, 5‐, and 3‐fold torus windows are generated in this model. © 2002 Scripta Technica, Electron Comm Jpn Pt 3, 85(5): 56–62, 2002
An error correction approach based on maximum likelihood estimation combined with hidden Markov models
Authors: Yonezaki Tadashi , Yoshida Koji , Yagi Toshio , Shikano Kiyohiro 
Published: August 2002

AbstractThis paper proposes an error‐correction algorithm for channel error using the hidden Markov model (HMM). The proposed method uses two probabilities calculated by the information source model (HMM) and the channel model, under the constraint of the received code sequence, and estimates the transmitted code sequence by maximum likelihood. Consequently, the robustness to error can be improved without adding error‐correcting code by applying the proposed method to the preprocessing of the existing code system. Using the code sequence obtained by quantizing the LSP parameters, the reduction of cepstrum distortion in error correction by the proposed method is examined. It is found that the distortion can be reduced by approximately 39% by the proposed method (16‐state HMM) for a code sequence with 3% random errors. © 2002 Scripta Technica, Electron Comm Jpn Pt 3, 85(5): 63–71, 2002
Radiation characteristics as a function of the gas flow rate emitted from argon torch plasma arc discharge
Authors: Iwao Toru , Miyazaki Hirokazu , Inaba Tsuginori 
Published: August 2002

AbstractWhen a reduction of the waste and dissolution of the iron are carried out by means of an arc plasma, the radiant power of the arc should be suppressed. In those cases the radiant power from the plasmas has to be precisely controlled.Therefore, we tried to measure the radian power from the torch plasma using a power meter. The radiant power was measured to be about 620 to 950 W for an external plasma length of 2 cm at a current of 100 A, with gas flow rates of 4 to 20 l/min (Normal), and increases in proportion to the 0.25 to 0.37 power of the gas flow rate and with the increment of external plasma length and the plasma current.The total radiant efficiency is 32 to 40% in the condition mentioned above in the sphere model. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 139(3): 1–8, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10006
A genetic algorithm for the optimal sequential partitioning problem
Authors: Araki Hajime , Kaji Taichi , Yamamoto Masahito , Suzuki Keiji , Ohuchi Azuma 
Published: August 2002

AbstractThe optimal sequential problem is defined as the problem of finding the minimum cost partition of the nodes of a directed acyclic graph into subsets of a given size, subject to the constraint that the precedence relationships among the elements are satisfied. A heuristic algorithm based on tabu search has been proposed for this problem [2]. However, there is a tendency for the solutions obtained by tabu search to become trapped in bad local optima in parallel graphs with random edge costs.In this paper we present a genetic algorithm for the optimal sequential partitioning problem. We develop an effective two‐point partial order crossover satisfying sequential conditions, which preserve better blocks that have a larger sum of edge costs. In this crossover we introduce the roulette selection method to escape local optima. We also assess the effectiveness of the algorithm. The results show that this proposed algorithm outperforms any other algorithm using tabu search in terms of solution quality. © 2001 Scripta Technica, Electr Eng Jpn, 135(4): 43–51, 2001
Optimum design approach for low‐speed, high‐torque permanent magnet motors
Authors: Mizutani Ryoji , Matsui Nobuyuki 
Published: August 2002

AbstractThis paper presents an optimum design approach for low‐speed, high‐torque permanent magnet motors. The approach is divided into two steps: the first consists of the rough estimation of torque by linear analysis, and the second the optimization of the motor configuration by nonlinear FEM analysis. Under restricted dimensional specifications and electrical requirements, a 16‐pole, 18‐coil permanent magnet motor with a rating of 600 Nm and 300 rpm was designed and constructed. © 2001 Scripta Technica, Electr Eng Jpn, 135(4): 52–63, 2001
Optimal operation of power systems constrained by transient stability
Authors: Chen Luonan , Ono Asako , Tada Yasuyuki , Okamoto Hiroshi , Tanabe Ryuya 
Published: August 2002

AbstractOptimal power flow (OPF) with transient stability constraints is a nonlinear optimization problem in functional space that is not easy to deal with precisely even for small‐scale power systems. Instead of directly tackling this tricky problem, in this paper, OPF with transient stability constraints (OTS) is equivalently converted into an optimization problem in Euclidean space via a constraint transcription, which can be solved by any standard nonlinear programming techniques adopted by OPF. The transformed OTS problem has the same variables as those of OPF in form, and is tractable even for large‐scale power systems with a large number of transient stability constraints. © 2001 Scripta Technica, Electr Eng Jpn, 137(1): 17–27, 2001
Configurations and characteristics of active canceling and compensating circuits for reducing common‐mode voltage generated by voltage‐source PWM inverters
Authors: Ogasawara Satoshi , Zhang Song , Akagi Hirofumi 
Published: August 2002

AbstractThis paper deals with active circuits for cancellation and compensation of common‐mode voltage caused by a PWM inverter. A nonnegligible amount of leakage or ground current flows through stray capacitors between stator windings and the motor frame due to a large step change in the common‐mode voltage at every switching operation of the PWM inverter. First, it is shown experimentally that the active common‐noise canceler (ACC), which has been proposed by the authors, is effective in reducing not only conducted EMI but also motor shaft voltage and bearing current. Next, a new ACC characterized by an isolated power supply is developed to enlarge the applicable voltage range in which it is possible to integrate the ACC with a PWM inverter. Furthermore, the authors propose another type of ACC, the purpose of which is not to achieve complete cancellation but to restrain only a slope in a change of the common‐mode voltage applied to the motor. As a result, the core size of the common‐mode transformer used in the active compensating circuit becomes considerably smaller. Some experimental results show good effects of the proposed active circuits on both ground current and conducted EMI. © 2001 Scripta Technica, Electr Eng Jpn, 137(1): 57–65, 2001