bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rounding error analysis of the triangular lattice and escalator algorithms
Authors: Iiguni Youji , Sakai Hideaki , Tokumaru Hidekatsu 
Published: July 2007

AbstractThis paper deals with the Triangular lattice (TL) and Escalator (ES) algorithms for recursive least squares filtering problems. First, systolic array implementations of these algorithms are compared. Next, analysis of fixed point errors for the normalized TL and ES algorithms are performed and the expressions for the steady state biases in the estimated coefficients are derived. Finally, the total effects of finite wordlength arithmetics on both algorithms are compared through a numerical example.
Methods of stabilization for linear time‐delay systems based on stability margin
Authors: Mori Takehiro 
Published: July 2007

AbstractSeveral simple methods are proposed to stabilize a linear time‐delay system with a feedback of the internal variables at two instants: the present and the past by the delay‐time. The methods are derived by virtue of the stability criteria obtained earlier for a linear system with a time‐delay. These criteria imply intuitively that the systems are stable if the stability margin of their simplified systems is greater than the magnitude of the residuals. Some of the four obtained methods include the time‐delay, while others do not. The stabilizability condition can be represented by scalar inequalities which can easily be proven. Once a parameter is found satisfactory for the criterion, the feedback law for the stabilization can easily be formed by using a conventional pole‐assignment method. The results were compared with those obtained earlier based on the same idea. The proposed methods are demonstrated with examples.
Switched‐element spherical array antenna for wide scan angle
Authors: Hori Toshikazu , Terada Noriyoshi , Kagoshima Ken‐Ichi 
Published: July 2007

AbstractThis paper proposes simple switchedelement spherical array antennas with variable phase shifters whose number is the same as that of the simultaneously excited elements. By employing the phase shifters, the total number of array elements can be reduced as to half that of the conventional switched‐element array. This small number of elements makes this antenna smaller in size and lower in cost. To confirm the design concepts, this antenna has been applied to mobile stations for satellite communication systems. Experimental results show the high performance of this antenna, particularly its wide‐angle scanning capability.
Stochastic distributed optimization algorithm
Authors: Fukao Takeshi , Yue Zhao 
Published: July 2007

AbstractExpect for special cases, the solution of the combinational optimization problem depends greatly on the heuristic approach. Recently, Kirkpatrick et al. proposed with success the “simulated annealing” algorithm based on the analogy to the statistical thermodynamics. The method has already been applied with success to the large‐scale combinational optimization problem, such as partitioning, allocation, and wiring in VLSI design. The algorithm based on the analogy to the physical system may not be considered as an analog approach in the sense that the discrete representation is used. It can provide the parallel and distributed representation of the events in a natural way. Although the present simulated annealing algorithm does not contain such a parallel and distributed representation, those ideas should naturally be introduced. This paper adopts a viewpoint which is more general than the physical model such as the Ising model, and discusses the stochastic algorithm and its distributed representation for the optimization from the viewpoint of the Markov field. Various schemes under such a parallelism, i.e., synchronization and distributed‐lumped analogy to the field are discussed. As an application, the result of distributed formulation and computation for the decomposition problem are presented.
Development of light beam CT system for measurement of ultrasonic wave fields
Authors: Akiyama Iwaki , Nakajima Masato , Waki Hisao , Yuta Shin'Ichi 
Published: July 2007

AbstractWhen an ultrasonic wave is irradiated perpendicularly by a coherent light beam, the ultrasonic wave behaves as a phase diffraction grating, and the light is phase‐modulated. Since the degree of modulation of the light is proportional to the line integral value of the sound pressure in the light‐beam path, the sound field can be reconstructed by measuring it in various directions and by applying the CT method. This paper describes a development of the light beam CT system for measuring ultrasonic fields and the obtained results. A system to measure the projection data from various directions was developed, and sound fields produced by various transducers were reconstructed. The results were compared with the experimental data obtained by a hydrophone and the numerically calculated values. The degrading of the quantitativity of this method due to the fact that the ultrasonic wavefront is not really a plane (this is a crucial point in the method), was examined by using a computer simulation. The results show that the errors are negligible in the far‐field region of a plane‐type transducer or in the focal plane of a concave‐type transducer. However, the errors are significant in the rest of the region.
Low‐sidelobe multibeam antennas fed by cluster horns
Authors: Yamada Yoshihide , Kagoshima Kenichi , Kobayashi Takehiko 
Published: July 2007

AbstractA multibeam antenna fed by cluster horns can reduce sidelobe level, and a design method for determining antenna parameters is described as well as its electrical properties. The horn size and the antenna aperture diameter are determined, and a relation between the horn excitation amplitude distribution and the sidelobe level is discussed. Degradation of sidelobe level is given as a result of errors in horn size, frequency, and excitation amplitude. The received mode analysis method is optimized when horns are displaced from the focal point of the antenna, and the excitation distribution is determined. Finally, results are described of the present method, which is applied to the domestic satellite‐borne multibeam antenna.
Performance evaluation for FCFS‐like group random access protocol on bus networks
Authors: Goto Kunio , Takahashi Yutaka , Hasegawa Toshiharu 
Published: July 2007

AbstractPerformance of bus‐type local area networks using CSMA/CD protocols, such as Ethernet, is known to deteriorate as the ratio of round‐trip propagation time to packet transmission time increases. In this paper, we propose a new FCFS‐like transmission protocol (FCFS‐GRA) in which each successfully transmitted packet includes the information of the number of packets having been successfully transmitted while being backlogged, and each busy terminal controls the timing of its transmission by the information.A queueing model which represents the bus system using FCFS‐GRA is described, and by solving an embedded Markov chain of simplified system states, throughput and delay are obtained. In more generel cases, throughput and delay distribution are obtained numerically by simulation. The performance of FCFS‐GRA is compared with that of CSMA/CD and it is found that the FCFS‐GRA protocol shows good performance even in the case of a long bus over 10 km.
FSK‐ASK transfer characteristic of the double‐mode oscillator with third harmonic oscillation
Authors: Umeda Hiroyuki , Nakano Takahiko , Shiraga Yoshiaki 
Published: July 2007

AbstractNumerous detailed studies have been made on the injection locking of the solid‐state microwave oscillator, but there have been few applications of the locked multimode oscillator to the communication system. The double‐mode oscillator with the third harmonic oscillation has the feature that it can easily be locked to the external signal and has two kinds of stable locked steady‐states. When an FSK signal is used as the external signal, the signal is converted into ASK signal, and the oscillator operates as an the FSK‐ASK converter. This paper discusses the fundamental operation of the FSK‐ASK converter with the following contents: (1) For the case where the frequency of the injected signal changes stepwise, the transient locking response of the oscillator is analyzed. It is shown that the upper bound for the FSK modulating frequency (modulation rate), for which the FSK‐ASK conversion can be realized, is determined by the rise‐time and the fall‐time and the fall‐time of the oscillator output; (2) the code‐error rate of the ON‐OFF amplitudes of ASK wave is calculated. It is shown that the signal can be detected with an error rate equal to or less than that of the FSK coherent detection; (3) The power spectrum desnsity and correlation time of ASK wave, as well as the noise suppression by the double‐mode oscillator are derived. Finally, an experimental example is shown for the typical basic characteristics, indicating the validity of the theory.
Optimal design problems of highly reliable systems and their solution methods by surrogate constraints algorithm
Authors: Hikita Mitsunori , Nakagawa Yuji , Nakashima Kyoichi , Yamato Kazuharu 
Published: July 2007

AbstractThis paper presents a solution method for the reliability optimization problem of systems which is formulated as a mixed‐integer nonlinear programming problem with multiple constraints. The system structure is series, series‐parallel, or complex. In the solution method, the optimal solution is obtained by solving the surrogate dual problem. Surrogate problems with only one constraint which appear in the optimization process are solved by a technique using dynamic programming. Some computational experiences are shown along with comparison with other approaches.
A synthesis of low‐sensitivity digital filters using t‐casade connection
Authors: Watanabe Eiji , Murakoshi Nobuo , Nishihara Akinori 
Published: July 2007

AbstractWhen we realize a digital filter, a low‐sensitivity structure is desired to produce less degradation of characteristics in finite word length. In addition, for the fast operation, a structure that can be parallelized or pipelined is preferable. The low‐sensitivity digital filter, a wave digital filter proposed by Fettweis, is well known. Taking into consideration the fore‐mentioned, we propose synthesis of a digital filter that will permit pipeline processing and possess low‐sensitivity as in a wave digital filter. First we show that a circuit structure usingT‐cascade connection of basic sections allows pipeline processing; we then derive a method for synthesis of a digital filter having this form of structure from a given transfer function inz‐domain. Then in the proposed method we demonstrate synthesis of not only IIR filters but also FIR filters in a unified fashion. A realization of basic sections used in circuit synthesis is shown and the effectiveness of our synthesis method is verified by examples.
An adaptive digital filter using a system of orthogonal functions
Authors: Kobayashi Masaki , Itoh Yosio 
Published: July 2007

AbstractThe FIR adaptive digital filter has been applied widely to the echo canceller, automatic equalizer, and the noise canceller. For the viewpoint of the realizable transfer function, the FIR filter can be regarded as an adaptive digital filter which adjusts the zeros of the transfer function under the strong constraint that the poles of the transfer function can exist only at the origin of z‐plane. This paper proposes an adaptive digital filter, which can adjust independently all adaptive parameters specifying the zeros, with the poles of the transfer function being placed at arbitrary positions within the unit circle of z‐plane. First, a system of orthogonal functions is described which can realize the poles of the transfer function at arbitrary positions within the unit circle of z‐plane. The adaptive digital filter utilizing this system of orthogonal functions is discussed. Finally, the effectiveness in convergence is demonstrated by computer simulation.
Low‐sensitivity realization of linear‐phase FIR digital filters using cascade form
Authors: Honma Hitoshi , Mori Yukio , Sagawa Masahiko 
Published: July 2007

AbstractIt is important from the viewpoint of economy to realize the digital filter with as little hardware complexity as possible. On the other hand, the theory of low‐sensitivity FIR filter is not advanced, compared with that of the IIR filter. From the viewpoint of minimizing the coefficient word‐length, an investigation of this problem is required. With this as background, this paper aims at the reduction of the coefficient wordlength of the multiplier, and proposes the cascade construction of the FIR filter. First, using the coefficient sensitivity, an evaluation function is defined and used to evaluate the degradation of response due to the coefficient quantization. Then the relation between the locations of zeros and the value of the evaluation function is discussed. It is pointed out that the zeros with relatively remote locations reduce the response degradation. A systematic construction of the low‐sensitivity structure is described, considering the relation between the location of zeros and the evaluation function. Finally, to show its effectiveness, several examples are handled by the proposed method.
Optimum primary radiator tilt angle of a shaped offset dual reflector antenna
Authors: Karikomi Masahiro , Kagoshima Kenichi 
Published: July 2007

AbstractWhen we shape reflector surfaces of an offset dual reflector antenna for a given desired aperture distribution, we create a phenomenon in which the direction of the reflected ray by the shaped surfaces and an assumed direction of radiation by geometric optics do not coincide. Hence, the characteristics of cross‐polarized waves are degraded. If we shape the surfaces at a tilt angle of the main dish with respect to the direction of the main radiation pattern, we found that the directional errors become extremely small between the direction of the actually reflected ray and that of the assumed direction of radiation by geometric optics for an optimum tilt angle. At this tilt angle, we can shape the reflector surfaces satisfying almost all of the conditions imposed by geometric optics. When we shape the surfaces at the optimum tilt angle, we obtain continuous surfaces which generate a desired axisymmetric aperture distribution along the radial direction. We can design an offset dual reflector antenna with low sidelobes and favorable characteristics for cross‐polarized waves.Based on this theory, we built an experimental offset Gregorian‐type antenna with aperture diameter of about 50 λ. Measured results revealed excellent characteristics for cross‐polarized waves and those for sidelobes. Thus, we confirmed the validity of the theory of shaping reflector surfaces.
Improvement of picture quality and coding efficiency using discrete cosine transform
Authors: Izawa Yuuji , Takizawa Masaaki 
Published: July 2007

AbstractIn the applications of still picture coding such as image data base, the progressive coding is effective in reducing the retrieval time and the transmission cost. For the block coding based on the discrete‐cosine transform (DCT), a study has been made on the progressive and successive transmission from dc to higher‐order ac components. In this scheme, the major cause of the picture quality degradation is the block distortion produced at the initial stage.This paper proposes two methods to reduce the block distortion where the lower‐order ac coefficients are determined from the dc coefficients transmitted at the first stage and applied the inverse‐DCT. The first method is to determine the lower‐order ac coefficients so that pixel values are smoothly connected at some points on the block boundary. The second method is based on the application of the interpolation filter utilizing the property of DCT. Furthermore, it is shown that by transmitting the difference between the DCT coefficients to be transmitted and the coefficients generated by the proposed method, the coding efficiency can be improved by 5 to 8 percent.
Comparison of traffic characteristics of gos control methods for a trunk group carrying multislot calls
Authors: Oda Toshikane , Fukuoka Hiroyuki , Watanabe Yu 
Published: July 2007

AbstractIn multislot circuit‐switched networks, it is necessary to apply a GOS control method to trunk groups to improve network utilization and to protect services against overload. As a GOS control method for multislot networks, this paper considers a trunk reservation method, split high‐usage group method, split final‐group method and virtual circuit method, which have also been studied for telephone networks. They are compared then by evaluating their blocking performance and peakedness of overflow and carried traffic involved. Based on numerical examples, it is shown that although the trunk reservation method is superior with respect to trunk utilization, there are some cases where the other methods are advantageous with respect to the ability to withstand overload and peakedness of traffic.
Composition of robust error control scheme using adaptive coding and its effect on data communication
Authors: Sato Takuro , Kawabe Manabu , Kato Toshio , Fukasawa Atsushi 
Published: July 2007

AbstractThis paper describes a robust error control scheme used for propagation paths especially involving a long time‐frame burst error as in mobile radio communication and its effect on actual data communication channels. This is an adaptive error control scheme based on forward error correction code and composed adaptively of plural coding modes.Here, the BCH code is used as a block code, the diffused code is used as a convolutional code, and 3–5 majority logic is used as a majority voting code. The optimum coding mode is selected automatically according to the status of data transmission channels composed of a radio transmission span and telephone cable transmission lines. Cyclic code is used as an error detection method to evaluate channel status.Under practical transmission circumstances, extremely high throughput efficiency of more than 70 percent is realized for 4800 bit/s data for transmission over the cellular network in Britain. This scheme has been presented at CCITT SG XVII as a standard scheme candidate.
Evaluation of token ring characteristics containing subnetworks of CSMA/CD‐LAN
Authors: Satoyoshi Tsutomu , Takahara Mikio 
Published: July 2007

AbstractAs the local area network (LAN) becomes popular, LAN systems which cover wider areas and which resolve traffic concentration in the system are going to be needed. This paper analyzes a system which consists of a token ring LAN as the main network to which some CSMA/CD‐LANs are connected with bridges. Such a system is called the “compound LAN system” in this paper. The optimum condition of this system due to the performance evaluation of the compound LAN system is shown by comparison with the throughput of each LAN. The results of analysis are confirmed by computer simulations. Moreover, the optimized scheme condition is confirmed by using the power function evaluation for the system.
Detection of multipath signal by cross‐channe‐interference measurement
Authors: Zhou Hong , Yoshida Susumu , Ikegami Fumio 
Published: July 2007

AbstractIn a multipath fading channel, the arrival time delay difference of multipath signals gives rise to an asymmetric transfer function of the channel, thereby causing cross‐channel‐interference (CCI) between in‐phase and quadrature channel components of a transmitted signal. This paper proposes the use of CCI for detecting multipath signals and roughly estimating multipath delay spread in a digital mobile communication environment.First, the relation between CCI and multipath signal delay time is analyzed under the assumption of static two‐ to three‐ray multipath signals, taking BPSK and QPSK as examples.Next, taking BPSK as an example, the existence of a close relation between CCI and delay time difference or between CCI and delay spread under quasi‐static and Rayleigh fading multipath signal conditions is shown by theoretical analysis and computer simulation. The correspondence between CCI and bit error rate (BER) performance also is studied by computer simulation, and good agreement is found.Finally, the relations obtained were confirmed by laboratory measurements. Accordingly, multipath signal can be detected from CCI. Moreover, rough estimation of delay spread and variation characteristic of BER can be obtained from CCI. Thus, CCI can be used as an effective piece of information for evaluating transmission quality in digital mobile communication.
Relation between spacing and receiving efficiency of finite rectenna array
Authors: Otsuka Masataka , Omuro Norihiko , Kakizaki Kenichi , Saitoh Seiji , Kuroda Michiko , Horiuchi Kazuo , Soejima Teruzane 
Published: July 2007

AbstractIn the rectenna array used for rectification of the microwaves received on the ground in the solar power satellite system, it is required that the rectenna elements have a high dc power conversion efficiency and that the element spacing is optimized so that the arriving microwave power is received efficiently and the number of elements can be reduced. In this paper, a microwave rectifier is fabricated in an integrated form with a microstrip line on a teflon substrate. A circular microstrip patch antenna is used. A high rectification efficiency, 66.7 percent is obtained at a microwave input of 750 mW and 75.7 percent for input of 500 mW.With this rectenna element, a 7 × 7 lattice array is formed and the variation of the receiving efficiency (the ratio of the power converted to dc to the input microwave power) is measured by varying the element spacing. On the other hand, the receiving efficiency is calculated for a given element spacing of this rectenna array from the circuit equation of the antenna system by deriving the mutual coupling between the elements. The relationship between the element spacing of a finite array and the receiving efficiency is obtained both experimentally and theoretically. This computation method is extended to the case with many elements so that the change of the receiving efficiency is investigated.
Wave impedance in the near field around the fundamental electromagnetic radiating elements
Authors: Yamaguchi Takashi , Okumura Yoshihisa , Amemiya Yoshifumi 
Published: July 2007

AbstractStandards for electromagnetic protection taking into account human health have been established in a number of countries. Most of the present standards are expressed in terms of the intensities of electric and magnetic fields or the power density of the irradiating electromagnetic field. Usually, for conversion among these quantities, the relationship in the electromagnetic field at a distance far away (far field, plane wave) is used. However, near the electromagnetic source where the electromagnetic wave is the strongest, the relationship among the forementioned quantities varies depending on the location of the observation point or the type of the source. Therefore, there are recommendations to reconsider the standard values.The purpose of this paper is to provide fundamental references for modeling the electromagnetic sources in various electromagnetic equipment to reconsider the protection standard of the near field, and to develop the electromagnetic shielding theory in the near field. In this paper, the distance characteristics and the spatial distribution of the electromagnetic wave impedance characterizing the nature of the electromagnetic wave are studied near the elementary radiating elements such as the electric dipole, magnetic dipole, half‐wave dipole antenna, small current loop and small helical antenna.