bluuebunny/crossref_metadata_2025_split huggingface dataset:
Shielding effectiveness of a metal sheet parallel to the axis of a circular loop
Authors: Yamaguchi Takashi , Okumura Yoshihisa , Amemiya Yoshifumi 
Published: July 2007

AbstractThe equation of the magnetic shielding effectiveness for a configuration made of a circular (transmitting) coil in a semi‐half space on one side of a metal sheet and a magnetic sensor in the space on the other side of the sheet has been derived by Moser for the case where the axis of the coil is perpendicular to the sheet.One of the objectives of the present paper is to derive an equation for the magnetic shielding effectiveness in the case where the coil axis is parallel to the sheet. This paper shows that this effectiveness is smaller by a certain amount than the case where a magnetic dipole is placed at the center of the transmitting coil instead of the coil. The amount of reduction is a function of the ratio of the coil radius to the distance from the center of the coil to the observation point.Another objective of this paper is to determine what kind of quantities can be obtained by the measurement method by the MIL‐STD‐285 which is used for the measurement of the shielding effectiveness of the wall of the shielded room. In this measurement, the magnetic field shielding effectiveness is derived by measurement of the induced voltage of the receiving coil when the transmitting and receiving coils with a diameter of 12 inches are placed on both sides of the sheet at a distance of 12 inches, respectively, from the sheet in a plane perpendicular to the sheet.It is shown that the result of such a measurement gives rise to a value almost equal to (or smaller by about 0.4 dB than) the magnetic shielding effectiveness in a hypothetical case where a magnetic dipole is placed at the center of the transmitting coil and a magnetic sensor is placed at the center of the receiving coil.
High‐speed pull‐in of a digital phase‐locked loop incorporating an and filter
Authors: Inoue Takashi , Tokunaga Manabu , Mori Shinsaku 
Published: July 2007

AbstractWith the rapid progress in high‐speed communication, there is increasing demand for a digital phase‐locked loop (DPLL) with a faster phase acquisition. This paper proposes a DPLL which uses an AND filter instead of a random walk filter (RWF) as the loop filter.It is verified that the loop can realize a faster phase acquisition without deteriorating the jitter suppression performance. The jitter suppression and phase acquisition performances are analyzed based on the theory of Markov chain, and it is shown that the proposed loop has a wider locking range. Then the phase acquisition speeds of the proposed loop, the conventional binary quantized DPLL, and the DPLL with inserted AND filter are compared for the same jitter suppression.It is seen that the proposed loop can drastically improve the phase acquisition performance for a large initial phase difference. The tendency remains the same even if a noise is added, and the jitter is small. Those properties are verified by a computer simulation with satisfactory agreement with the theoretical analysis.
Design of corrugation depth and velocity dispersion characteristics of elliptical corrugated horn
Authors: Shogen Kazuyoshi 
Published: July 2007

AbstractWith a view for use as a primary feed for the shaped beam antenna on board the Broadcast Satellite 3, a design of the corrugation depth and a study of the velocity dispersion characteristics were carried out. The elliptical corrugated horn is approximated with an elliptical corrugated waveguide. The boundary conditions are determined by connecting the electromagnetic field in the corrugation with the hybrid mode in the waveguide at the boundary. From the solution of this boundary condition equation, the analysis other than that for the balanced hybrid mode is possible. By means of this method, a design method is demonstrated for corrugated grooves satisfying the elliptic balanced hybrid condition. Further, the κ‐β characteristics of the elliptic corrugated waveguide fabricated for test are computed and measured.
Synchronization and multiplexing of HDTV signals for transmission in broadband ISDN
Authors: Kinoshita Taizoil , Eto Yoshizumi , Nakahashi Tomoko , Sakaki Masanori 
Published: July 2007

AbstractWhen a high‐definition video signal such as HDTV is to be transmitted in a Broadband‐ISDN with a hierarchy, it is desirable that the video transmitter/receiver systems as well as the transmission system operate asynchronously, so that both synthesis and editing of the video are easier. It is also important to realize clock synchronization/transmission multiplexing without a deterioration of picture quality.From such a viewpoint, this paper first proposes a video stuffing method, which is a video/transmission clock synchronization method based on the concept of the synchronizer. Then the proposed multiplex video transmission system combines the synchronization detection for the video and the transmission in the receiver, based on the integer relation between the video block and the transmission frame. Lastly, the synchronous digital hierarchy (SDH) (STM 4‐frame or STM 1‐frame) transmission is investigated (it uses the HDTV encoding equipment); the SDH can transmit the Broadband‐ISDN signal with H4 × 4 or H4 rate, and the effectiveness of the proposed system is demonstrated. As a result of the experiment, the three clocks for the transmitter/receiver as well as the transmission system operated asynchronously, and a satisfactory video can be transmitted and reproduced without the video synchronization detection in the receiver, and without a deterioration of picture quality.
Performance of trellis‐coded 16‐QAM/TDMA system for land mobile communications
Authors: Sampei Seiichi , Kamio Yukiyoshi 
Published: July 2007

AbstractThe digital cellular telephone system is considered in various countries. It is a system which is more attractive than the conventional analog transmission system in the sense that various data can be transmitted using the same transmission band. In practice, it is very difficult to realize composite transmission of various data or the data transmission of the ISDN terminal. For such a situation, this paper proposes the trellis‐coded, 16‐QAM, six‐channel TDMA system. The proposed system includes various elaborations to improve the transmission characteristics, e.g., the fading distortion estimation by inserting the pilot symbol, the space diversity with maximum ratio combining, the symbol interleaving, and the two‐frequency hopping. A computer simulation is executed for such a system to examine its performance. It is seen as a result that the spectral efficiency is improved greatly and the high‐quality transmission is realized, compared to the systems considered in the United States and in Europe.
3‐GHz band burst mode earth station transmitter
Authors: Saito Takaya , Inoue Takeo , Shimokawa Kiyoshi 
Published: July 2007

AbstractTo reduce the size and the cost of the earth station equipment for satellite communication, a 30‐GHz band burst mode earth station transmitter is developed. In this case, the transmitter can access seven 30/20‐GHz band transponders on the CS‐3 transponder hopping system. Wideband and high‐power characteristics are required for the transmitter with the transponder hopping system. For this purpose, a helix‐type traveling‐wave tube (TWT) transmitter is newly developed to replace the conventional klystron tube, realizing wideband characteristics. The anode voltage switching method is developed and used for the transmitter so that the output of the 30‐GHz band helix TWT is increased. The anode voltage of TWT is made ON/OFF (burst mode) in accordance with a time‐advanced control signal from TDM A equipment to satisfy the thermal condition for the helix slow‐wave circuit and to reduce the power consumption. The major performances are as follows. The output power of 150 W is achieved by combining two tubes under the duty 50 percent or less and the power variation at 150 W is 1 dB/1 GHz or less. The rise and fall time of anode voltage is less than 3 μs.
Monopulse pattern‐forming method for an off‐focus RF sensor
Authors: Ueno Kenji 
Published: July 2007

AbstractTo improve the accuracy of the beam‐pointing direction of the satellite‐borne antenna, it is effective to attach an accurate RF sensor to such an antenna. On the other hand, it is not possible to place a monopulse horn for the RF sensor at the focal point of the antenna due to the use of the multihorn approach in the communication signal horn. Often the monopulse pattern is significantly degraded.In this paper, a method is presented for forming a desired monopulse pattern even under such an adverse condition. The least‐square method is used for determination of the amount of adjustment for the amplitude and phase for each horn. It is shown that the type of tracking receiver is related to the evaluation of the obtained pattern. At the same time, the tracking receiver is related to the evaluation of the obtained pattern. At the same time, the tracking receiver is modeled and a pattern evaluation method is proposed by observing the angular detection error at the output end of the tracking receiver. As an example, the present method is applied to the RF sensor displaced by six times the 3‐dB beamwidth in an antenna with an aperture diameter of 350 wavelengths. It is found that a monopulse pattern is acquired with distortions as small as those for an RF sensor on the focal point and the angular detection error is about one‐fourth the results in the conventional method if three constraint points on the difference pattern are chosen.
Power loss distribution in a circular‐cylindrical human body model produced by electromagnetic wave irradiation from surface magnetic current sources
Authors: Araki Noriyuki , Morita Nagayoshi 
Published: July 2007

AbstractThree‐dimensional power loss distributions for noninvasive electromagnetic hyperthermia are. analytically calculated. The dependence of the distributions along the longitudinal direction of the human body on the two types of polarization direction is investigated in detail. A uniform infinitely long dielectric circular cylinder is used as a model of the human body; magnetic current sources within limited regions on conducting planes are used as models of waveguide apertures.Three types of models are considered for the exterior region of the human body: a model with a water layer and an air layer, a model using only air, and a model using only water. Power loss distributions are calculated for two typical types of polarization, TE‐ and TM‐types, and for 100 and 60 MHz. We conclude that for localization of power‐loss distribution along the longitudinal direction, the TE‐type is more desirable than the TM‐type and that the water‐bolus should be located along the longitudinal direction.
HPA arrangement method to improve isolation among output ports on a multiport amplifier
Authors: Yamamoto Kazuichi , Tanaka Masayoshi 
Published: July 2007

AbstractA multiport amplifier (MPA), which has multiple input and output ports and is composed of an array of high‐power amplifiers (HPAs), is promising as an onboard high‐power amplifier for mobile satellite communications. It is necessary to keep the characteristics of the HP As and other components as uniform as possible to realize the MPA hardware. Since the deviation in characteristics degrades the isolation among the output ports of the MPA and causes signal interference problems, it is important to improve the isolation.An effective MPA configuration and an HPA arrangement to improve the isolation are made clear from the viewpoint that the isolation among the output ports depends on the HPA arrangement when the HPAs have deviation in characteristics.This paper describes the isolation improvement principle and an effective MPA configuration to improve the isolation. Also, proposed is an algorithm to determine the HPA arrangement that optimizes the MPA isolation without affecting the MPA output power. It is shown that almost an optimum HPA arrangement is obtained using the algorithm. The effectiveness is confirmed by experiment.
The application of a short‐time DFT to a hilbert transformer
Authors: Kishi Masahichi 
Published: July 2007

AbstractThere is an urgent need to reduce the frequency occupancy bandwidth over speech channels to prevent radio resources from being exhausted. A Hilbert transformer plays the role of efficiently reducing the occupied bandwidth in such high‐efficiency systems as single‐side band (SSB) or RZ SSB.In this paper, it is shown that a Hilbert transformer may be implemented using the instantaneous spectrum concept and then applied in communications systems. The new Hilbert transformer described in this paper is based on the concept that the Hilbert transform is fully realized in the frequency domain by exchanging the complex real part with the complex imaginary part of the instantaneous spectrum, which is then analyzed using a short‐time DFT. The Hilbert transformed output signals are then synthesized from these exchanged instantaneous spectra through a short‐time IFT. The short‐time DFT Hilbert transformer is shown to be superior to the standard minmax Hilbert transformer proposed by Rabiner et al. by means of a discussion of the ideal unit response and through computer simulations. It is also shown that The concept can be applied in practical communications systems due to the fact that it has the property of being free from the synchronization of a DSP processing clock.
Affine transformations for compensating linear distortion: An application to linear signaling in mobile radio
Authors: Suzuki Hiroshi , Yoshino Hitoshi 
Published: July 2007

AbstractWith the progress in mobile communication as the background, researchers have become interested in digital signaling techniques. The quadrature modulator and the quadrature demodulator are employed in those techniques.This paper aims at the suppression of the waveform distortion in such a quadrature modulator/demodulator and proposes the affine transformation distortion compensation for the linear distortion (ADC). The linear distortion is attributed to: (i) dc offset in the baseband signal; (ii) unbalance of I/Q amplitudes; and (iii) phase offset of quadrature reference carrier. It is shown that those can be eliminated by ADC. A method is shown which estimates the ADC parameters of the quadrature modulation from the output of the level detector for the modulated wave. A method is also shown which estimates the ADC parameters for quadrature demodulation from the detected component in the received wave. ADC is actually implemented in the QPSK transmission system using the decision feedback equalizer. The characteristics are examined experimentally, and the usefulness of the method is demonstrated.
Layering and partitioning of network architecture
Authors: Kajima Makoto , Uchinuma Hiroshi , Inoue Yuji 
Published: July 2007

AbstractThe telecommunication network is a large‐scale and complex network which is described by various expressions according to the purposes, e.g., the provision of services and operation of the network. Another point to note is that there are remarkable technical innovations in the network configuration. Also, there are shifts from the analog to digital system as well as the synchronous transfer mode (STM) to asynchronous transfer mode (ATM) in the digital system.This paper presents two concepts, i.e., layering and partitioning, to arrive at the unified representation of the such a diversified and complex network based on the basic concept of the network architecture. It is expected that those concepts will have important roles in the future integrated networks, as the concepts that clearly specify the network structure, by pinpointing the essence of the network without being affected by the implementation techniques.
Multipath allocation control in a communication network by the cooperative distributed multiagent model
Authors: Minato Kenji , Okumura Yasuyuki , Kishimoot Ryozo 
Published: July 2007

AbstractThis paper proposes an application method of the cooperative distributed multiagent model in multipath allocation algorithm and confirms its valid calculation results by realizing this model in a distributed computer environment. The multiagent model in this paper is an environment where each agent has the same function of asynchronous and parallel calculation and no globally controlling agents exist.To realize this model, this paper proposes an appropriate dividing method of the multipath allocation problem for asynchronous and parallel calculation, a unifying method of each agent's answers and interagent communication protocols. It also compares the required calculation time and the number of allocated paths of a single agent with that of the multiagents and shows the practical calculation ability of the multiagent model.
Performance analysis of end‐to‐end transfer delays for multipacket messages in packet‐switching networks
Authors: Inai Hiroshi , Murata Masayuki , Miyahara Hideo 
Published: July 2007

AbstractWhen a long message such as file is to be transmitted in a packet‐switching network, the source node segments the message into a number of packets and the packets are transmitted to the network. Those packets are transferred to the destination node through several intermediate nodes and then reassembled into the message.This paper models the packet‐switching network into a tandem queueing network. By analyzing the model, the performance of message transfer in the packet‐switching network is evaluated. The discrete‐time system is considered in the analysis.An algorithm is presented which strictly derives the distribution of time needed in the transfer of all packets composing the message from the source node to the destination node (message transfer time).In the numerical example, it is assumed that the service time at each node is composed of the packet processing time and the packet transmission time. The effect of the packet size on the mean and variance of the message transfer delay is analyzed. The case where the message size and the number of intermediate nodes are increased also is considered.
Conformal array antenna for mobile satellite communications
Authors: Chujo Wataru , Konishi Yoshihiko , Ohtaki Yukio , Fujise Masayuki 
Published: July 2007

AbstractIn the case of mobile satellite communication antennas for automobiles and aircraft, a necessary electrical characteristic is to scan the beam over a wide angle. Also, from the viewpoint of aerodynamics and design, conformal arrays are desirable which are fit to the shape of the moving body.This paper discusses the radiation characteristics of a conformal array suitable for mobile satellite communications. In addition, a one‐piece fabrication of a conformal array is carried out and its electrical characteristics are evaluated.First, it is shown by means of computation of a 16‐element partial spherical array with icosahedron arrangement that the radiation characteristics can be varied by adjusting the curvature in the conformal array and there exists an optimum value. Next, a trial fabrication is carried out to establish a one‐piece fabrication technique. The test results are described for a 16‐element hemispherical array made by a vacuum‐forming method and a 16‐element partial spherical array made by a roundfaced compression method which is employed to improve the fabrication accuracy of a thin partial spherical array. Excellent single‐element characteristics and array radiation characteristics are obtained with the 16‐element partial spherical array using the round‐faced compression method. Hence, the validity of the fabrication method is verified.
Analysis of annual maximal and minimal temperatures for some European cities by change point methods
Authors: Jarušková Daniela , Rencová Monika 
Published: July 2007

AbstractThe test statistics for detecting a change in a location parameter of annual maxima and minima series together with several methods for finding critical values were proposed. The methods were applied to temperature series measured at five meteorological sites—Bruxelles, Cadiz, Milan, St. Petersburg, and Stockholm. Copyright © 2007 John Wiley & Sons, Ltd.
Decomposition and parallelization strategies for solving large‐scale MDO problems
Authors: Grauer M. , Eschenauer Hans A. 
Published: July 2007

AbstractDuring previous years, structural optimization has been recognized as a useful tool within the discriptines of engineering and economics. However, the optimization of large‐scale systems or structures is impeded by an immense solution effort. This was the reason to start a joint research and development (R& D) project between the Institute ofMechanics and Control Engineering and the Information and Decision Sciences Institute within the Research Center for Multidisciplinary Analyses and Applied Structural Optimization (FOMAAS) on cluster computing for parallel and distributed solution of multidisciplinary optimization (MDO) problems based on the OpTiX‐Workbench. Here the focus of attention will be put on coarsegrained parallelization and its implementation on clusters of workstations. A further point of emphasis was laid on the development of a parallel decomposition strategy calles PARDEC, for the solution of very complex optimization problems which cannot be solved efficiently by sequential integrated optimization. The use of the OptiX‐Workbench together with the FEM ground water simulation system FEFLOWis shown for a special water management problem. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parameter identification with sensitivity assessment and error computation
Authors: Johansson H. , Runesson K. , Larsson F. 
Published: July 2007

AbstractIn this paper a particular framework for the parameter identification (calibration) of constitutive models is discussed. The framework involves the formulation of an optimization problem as the stationarity condition for a Lagrangian, whose arguments include an additional costate field in order to incorporate the state equation. This formulation has two distinct advantages: (1) The sensitivity of parameters with respect to uncertainties in the observed data can be assessed efficiently using a dual method, which compares favorably with the more conventional primal method, and (2) The errors arising from the FE discretization can be computed using the same dual method, which is an additional bonus. In fact, both the sensitivity and the discretization error can be estimated in an arbitrarily chosen “goal quantity” (or quantity of interest). Two numerical problems, one in terms of stationary groundwater flow (elliptic, in space) and another in terms of transient moisture diffusion in wood (parabolic, in space‐time) illustrate the salient features of the proposed algorithm(s). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)