bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties of tapered circular waveguide cutoff filters for TE01 mode millimeter‐waves
Authors: Shirasaki Hirokami , Ishihara Fujio 
Published: July 2007

AbstractA differential equation is derived for the TE01 mode of a tapered waveguide by satisfying all boundary conditions at the connecting parts of the waveguide. The reflection and transmission coefficients are obtained by the Runge‐Kutta method for cutoff filters using circular waveguides with the linear and n‐th power cosine tapers for millimeter waves. Using the previously published experimental data, the validity of the authors' method was examined by comparing their results for attenuation, phase and delay characteristics with those experimental values. Design charts were constructed for cutoff filters. As an example, the profile for a miniaturized high‐pass filter which satisfied the given specifications for transmission of millimeter waves was determined.
Approximate analysis of memory contention in a multiprocessor system with a single bus
Authors: Nogami Shinya , Sumita Shuichi 
Published: July 2007

AbstractThis paper considers a multiprocessor system in which a memory module and two groups of processors with different access rates to the memory are connected through a single bus. The holding time in the common bus is assumed to follow the general distribution. A new approximate analysis method is proposed. When the holding time in the common bus follows the same exponential distribution, the problem reduces to the BCMP queueing network model, for which the analysis is easy. However, when the processing discipline is FIFO, and the holding time of bus follows the general distribution, a strict analysis is difficult since there is no product‐form solution. For such a case, the system is modeled as a closed queueing network, and a group of processors is aggregated to a single processor with the equivalent common bus occupancy. Then the object model is replaced by a small‐scale model for which the analysis is easy. Using such a model and known results, the approximate solution is obtained for the characteristic parameters by iterative calculations. At the last stage, a numerical example is presented for the case where the holding time of the bus is assumed as constant. Comparing the result with the result of simulation, the range of application for the approximate method is indicated.
Equivalent transmission lines of wire antennas and the radiation mechanism
Authors: Nakamura Takashi , Oda Keisuke , Yokokawa Senji 
Published: July 2007

AbstractThis paper proposes a new analysis method for a linear antenna by obtaining its equivalent nonuniform line. Based on the theory of transmission lines, the radiation mechanism of the linear antenna was clarified. The traveling‐wave mode method which was effective for the analysis of meandering lines was extended. Its equivalent distributed constants are complex variables depending on frequency and position. The calculated results for various antenna characteristics agreed with those by the moment method, providing a proof of the effectiveness of the present analysis method. The effective power on the conductor based on the equivalent nonuniform line for the antenna thus obtained was determined. The radiation mechanism of the antenna through the attenuation of the power was examined. As a result, in a standing‐wave type antenna, it was shown that the transmission component which was radiated gradually from the entire part of the antenna and the storage component which radiated at the terminal part, could be handled separately. In a traveling‐wave type antenna, the transmission component radiated from the entire antenna. However, a dominant radiation in the vicinity of the bending when the angle of bending becomes large was clarified.
Reflection and transmission of gaussian beam of a uniaxially anisotropic medium
Authors: Sonoda Takahiro , Kozaki Syogo 
Published: July 2007

AbstractReflection and transmission when a three‐dimensional Gaussian beam is launched obliquely into a uniaxially anisotropic medium whose optical axis has arbitrary direction are analyzed. This problem is solved by using Fourier transforms. Solutions of reflected and transmitted beams having integral form are calculated numerically by using a numerical integral. As a result, physical considerations are presented and the G‐H shift (negative) is discussed.
Aircraft‐and satellite‐borne synthetic aperture radar images of ocean waves in orbital motions
Authors: Sakata Tetsu , Wakasugi Koichiro , Matsuo Masaru 
Published: July 2007

AbstractBecause of its all‐weather capability and high resolution, the synthetic aperture radar (SAR) is very effective for remote sensing of the ocean. However, for a moving target such as ocean waves, they affect the SAR images as a phase distortion. This paper considers the orbital motion of the ocean waves. By modeling the waves with an ensemble of the moving points, the SAR image is computed. Previously, the discussions were limited to the case of snapshot observation of the slowly moving ocean waves with a rather long wavelength by a high‐speed SAR such as that on a satellite for simplicity of the model. In this paper, this restriction is removed and the estimate and study of the SAR image become possible including a low‐speed SAR such as the one on an aircraft and waves with a short wavelength. As a result, it is pointed out that the phase velocity of the ocean waves cannot be neglected in a low‐speed SAR so that the wavelength of the SAR image is expanded or compressed and that the SAR image is strongly dependent on the ocean waves and the SAR parameters.
Basic characteristics of variable rate interframe video coding
Authors: Nomura Mitsuru , Fujii Tetsurou , Ohta Naohisa 
Published: July 2007

AbstractRecently, interest has been increasing greatly in the various services and possibilities offered by the new communication media. At the same time, the demand for higher‐speed communication also has increased. Therefore, flexible systems based on ATM (asynchronous transfer mode) have received particular attention because they can meet these demands by transmitting various types of information in a unified form. In this case, the transmission method can utilize effectively the variable rate characteristics of the information sources. Thus, the understanding of basic characteristics of the coded information sources becomes important. This paper investigates the basic characteristics of the variable rate video coding from this viewpoint. The interframe coding method is considered and the burst characteristics of the information as well as the improvement due to variable rate coding are analyzed, using simulation methods. The results relating to video conference scenes show that the peak rate is about three times as much as the average rate and the quality improvement expressed in minimum SNR is about 5 to 10 dB.
Electromagnetically coupled microstrip antennas with circular polarization
Authors: Kominami Masanobu , Yasuda Hirohiko , Uchibori Takuji , Rokushima Katsu 
Published: July 2007

AbstractRecently, electromagnetically coupled microstrip antennas have been studied extensively. This paper proposes a new microstrip circularly polarized antenna in which an orthogonal mode with a phase difference of 90° is generated on a radiating element via the path length difference of the traveling wave currents on the strip transmission line coupled electromagnetically at two points with the radiating element. By experiments and numerical calculations, the operations of the circular loop and square patch circularly polarized antennas based on the present principle are confirmed. The radiation pattern, input impedance and current distribution are studied. The proposed circularly polarized antenna employing electromagnetic coupling has less spurious radiation from the transmission line than the direct coupled two‐point fed structure and is enabled to provide an excellent circular polarization with a simple construction. Circular polarization can be obtained in a wide angle. If the input and load terminals are interchanged, the direction of the circular polarization can be switched easily.
A crossed‐slot antenna backed by a rectangular cavity
Authors: Itoh Kiyohiko , Iizuka Hiroshi , Ogawa Yasutaka , Baba Hiroshi 
Published: July 2007

AbstractA shallow cavity‐backed slot antenna has been used as a flushmounted antenna in a high‐speed moving object since it is resistant to vibration and shock. This paper presents a theoretical analysis for a circularly polarized antenna consisting of a crossed‐slot along the diagonal line on the surface of a rectangular shallow cavity. As a method of analysis, the reaction matching method has been used which was developed by Richmond as a form of the moment method by Harrington. By means of this method, the input impedance can be obtained over a broad frequency range in the case where an offset feed and a multiple feed are used. In this paper, an offset symmetric two‐point feed is used so that the impedance matching can be realized easily. The input characteristics and the radiation characteristics of the antenna element are obtained numerically and the obtained results are discussed.
Fluid model to analyze overload characteristics of a telephone network
Authors: Ohta Masataka 
Published: July 2007

AbstractTo study overload characteristics of a telephone network, a simple and useful method using fluid approximation is presented. Taking a two‐stage telephone network as an example, it is shown that the circuit trunk part is congested under an overall overload and the outgoing register part is congested under a focused overload. Since under overload conditions the number of calls in a telephone network is large enough that the law of large numbers is applicable, the traffic flow can be regarded as a deterministic continuous process. Specifically, a fluid approximation can be applied. The calculation time of this method is much less than that of the simulation method. Accordingly, the overload characteristics of a telephone network, which have been analyzed mainly through simulation, can now be analyzed by simple numerical calculation. This fluid model can be applied to the overload analysis of not only telephone networks, but also other communication networks.
High‐speed thermal printing and document feed technique for facsimile using MMR coding scheme over telephone network
Authors: Nakamura Koozoo , Kojima Yasuyuki , Tadauchi Masaharu , Sakata Kunihiro 
Published: July 2007

AbstractModified MR (MMR) coding is the coding method for G4 facsimile. It has a better compression performance than the MR (modified read) code, which is a coding scheme for G3 facsimile. Consequently, the facsimile using the MMR code is expected to realize a high‐speed transmission. In the facsimile using MMR code, a high‐speed printing is also required to achieve such a highspeed transmission. From such a viewpoint this paper discusses the high‐speed thermal printing, suited to the facsimile over the telephone network using the MMR code. A high‐speed transmission by the black ratio control is considered, where the printing speed is varied according to the number of black pixels in the line. Detailed parameters are presented for the black ratio control which can realize almost the same printing speed as the transmission speed. Next, as the means toward a practical system, a high‐speed document feed technique is considered, together with its realization, where the document feed is performed smoothly following the change of the printing speed. It is shown by computer simulation that the loss of the printing time due to this mechanism is at most 10 percent for the usual document. Finally, to reduce the number of feed stops in a page, a high‐speed document feed is proposed where the maximum feed speed is limited according to the number of buffered coded bits. It is verified by computer simulation that a high‐speed and smooth document feed can be realized without a stop for the usual document.
Measurement accuracy of carried traffic for the loss system with heterogeneous inputs
Authors: Yamada Hiroshi 
Published: July 2007

AbstractThe integrated service digital network aims at providing communication service by various kinds of media, such as speech, data and image, by a single communication network, realizing higher‐level convenience and economy compared with the communication networks for individual services. In its design and management, the traffic problem must be solved for the sharing of a system by heterogeneous traffic. This paper discusses especially the measurement accuracy for the carried traffic when the channel is shared by heterogeneous traffic, which is important in the management of traffic statistics. To discuss the measurement accuracy of the carried traffic, the autocovariance function which represents the correlation between measured values with the time difference of the scanning period must be determined. As a fundamental model, the strict solution is derived for the autocovariance function of the simultaneous connections in the loss system with two kinds of inputs. Using the result, the relation between the variance of the measured values and the scanning period is determined, and the determination of the optimal scanning period is discussed. Since the calculation of the strict solution becomes difficult with the increase of the number of channels, a practical approximation expression is proposed for the autocovariance function.
Electromagnetic wave propagation in a two‐dimensional tunnel with a modified cross‐junction
Authors: Matsunaga Toshiaki , Uchida Kazunori , Noda Takeaki 
Published: July 2007

AbstractThis paper investigates theoretically and experimentally the electromagnetic wave propagation in a two‐dimensional tunnel with a modified cross‐junction in connection with radio communications in tunnels, underground, urban areas with high‐rise buildings and others. Modal expansions and Fourier transform are used as an analytical method, and the surface impedance model is employed as a boundary condition on the tunnel walls. The results presented here can be applied to special tunnels such as the T‐type, modified T‐type, L‐type and step‐type. Experiments based on a microwave simulation are performed by using tunnels composed of concrete slabs. It is found that, concerning electric field intensity, experimental and theoretical results agree well.
Design of two‐stacked circular loop yagi‐uda array antenna
Authors: Korekado Toshikazu , Okuno Kiyoshi 
Published: July 2007

AbstractA broadband multiple element Yagi‐Uda two‐stacked circular loop antenna is proposed in which two circular loop antennas with a high gain and a broadband are stacked in the broadside direction. In the two‐stacked structure, circular dual‐loop antennas are used in which the loops are connected with a parallel twin wire only for projector and are fed at the center. The antennas are analyzed numerically by setting equivalent antennas consisting of the loops and the parallel twin wire. Detailed design data for each parameter are obtained.The effect of the stack spacing of the loops on the radiation characteristics is significant. An optimum value is obtained at Dij = 0.45 – 0.60 λ. It is shown that the impedance loss can be compensated by the stab method. Also, an example of the design of a high gain antenna based on the design data is presented.The validity of the design procedure is confirmed experimentally. With an eight‐element array, a sharp beam is obtained with an H‐plane half‐power angle of about 30 degrees. The maximum actual gain is 11 dB, and the 3‐dB bandwidth is about 270 MHz. This high gain and broadband antenna is an improvement of the actual gain by more than 4 dB in comparison with a dipole array with the same dimensions. At present, this antenna is in the class of broadband antennas with the maximum gain.
Traffic analysis of an integrated voice/data system by means of pseudo‐data call concept
Authors: Akiyama Minoru , Ichiya Yasuo 
Published: July 2007

AbstractSince the model for the voice/data multitraffic processing system was proposed, various analyses have been made for the system. However, the traditional analysis derived only the average and the variance of the data call queues.A general and practical method of analysis has not been presented for the waiting time distribution of the data calls, which is important as the service criterion. This paper proposes an approximate method of traffic analysis for the integrated voice/data system, which is applicable to data calls with the holding time following the general probability distribution.The method is to represent the holding time distribution of the data call following the general probability distribution as a sum of several pseudo‐data calls following exponential distributions. By this method, not only the average waiting time but also the distribution of the waiting time can be calculated relatively easily.As in the design for a voice communication network, the integrated network can be designed so that the given service criterion is satisfied by 99 percent of the data calls in the data system. As an example, the case of facsimile as the data source is examined. The result by the proposed method agreed well with the result of simulation, indicating that a practically sufficient accuracy is realized.
High‐speed broadband circuit switching system architecture
Authors: Chiba Yoshikazu , Hiraide Kazuhiro , Kondo Fumio 
Published: July 2007

AbstractThis paper considers the speed of communication where NTSC and HDTV video signal is encoded into digital forms, and proposes a high‐speed broadband circuit switching system which realizes the integrated services covering communication services and distribution services. The former include the end‐to‐end communication such as TV conference and the video retrieval such as image inquiry system, and the latter includes the CATV.The proposed method has the following features: (1) The communication services and the distribution services are distinguished by using layer 3 of I interface protocol. The video channel selected by the subscriber is transferred between the subscriber and the service processing node of the video distribution system, using the high‐level layer signal; (2) considering the uncertain demand, a building block structure is adopted, where the unit is the small‐scale independent switching and distribution module with several tens to several hundreds of subscribers; (3) the load‐function distributed control scheme is adopted.In the communication services, the functions are divided into the modules of subscriber accommodation, intermodule connection, inter‐office signal processing and system management. In the distribution services, the divided modules such as the selection of video channel and the interface processing to the video operation center are executed in the almost complete processing within the module, which helps to reduce the communication traffic between modules.
Atm cross‐connect switch using folded banyan switching network with bypass links
Authors: Okamoto Satoru , Obara Hitoshi 
Published: July 2007

AbstractA high‐speed multiplex transmission system has recently been proposed based on ATM, where the information is divided into fixed‐length blocks called cells, and transmitted on asynchronous multiplexing basis. As the switch to be used in the transit node in such a transmission system, various kinds of switching networks have been proposed, composed of two‐input × two‐output switch elements with internal buffers. Among those, the multistage buffered Banyan structure, which is a cascade connection of two Banyan networks as the distribution and routing networks, is of a distributed structure, being suited to LSI implementation. The network is a promising candidate since it realizes the self‐routing and is stable against a variety of traffic. However, this switching network has a problem in that the delay is increased with the scale of the network, and the in‐service expansion of the switching network is not easy.This paper proposes a new network topology of the Banyan network with bypass links, together with the self‐routing method, and describes its performance. The network is composed of the distribution and routing networks with bypass links between individual unit switches. By transferring cells from the distribution network to the routing network through the bypass links at appropriate stages, the delay is reduced. The in‐service expansion of the system is made easy.
Trellis coding with improved bit error performance
Authors: Umeda Masatoshi , Murata Masashi , Morinaga Norihiko 
Published: July 2007

AbstractIn a conventional Trellis coded modulation (TCM), the error‐event probability is minimized by designing the Trellis code so as to achieve the maximum free Euclidean distance (ED). This paper proposes a new coding technique which improves the post‐decoding bit error rate without changing the ED‐structure of the conventional TCM code. This is achieved by channel coding with mapped signal sets having minimum Hamming distance (MHD) on information bits for error events generated at free ED.First, this mapping was obtained by calculating Hamming distances on information bits for error events generated at free ED for all code mappings by using a computer, which requires a large amount of calculation. We show that such codes for multiphase modulation are constructed by a simple coding method without this much calculation. Also, its effectiveness is confirmed by the simulation.
A study on hybrid motion video coding schemes– block size, comparison of dct and vq schemes, loop filter
Authors: Kato Yoichi , Okubo Sakae , Suzuki Yutaka 
Published: July 2007

AbstractTo design a highly efficient video codec, comparisons of available techniques from various viewpoints are necessary so that the coding scheme and parameters are chosen appropriately. In recently presented papers and equipment, many systems use motion‐compensated interframe prediction and DCT or VQ schemes for the prediction error coding. A loop filter often is adopted to improve coding efficiency.This paper compares DCT and VQ schemes in an interframe coding scheme, on an optimal blocksize for interfreme prediction error signal coding and on the effect of loop filtering from the viewpoints of coding efficiency and reproduced image quality. Simulations using actual image sequences show that the optimal block size is 4 × 4 or 8 × 8, that the loop filter improves significantly the coding efficiency and reproduced image quality, and that DCT and VQ schemes give nearly the same efficiency with an appropriate loop filter.
A digital phase‐locked loop for stuffing synchronization systems
Authors: Rokugo Yoshinori , Goto Masataka , Hirosaki Botaro 
Published: July 2007

AbstractStuffing synchronization systems are now being applied actively to new fields such as digital cross‐connect and SONET. In stuffing synchronization systems, however, the analog PLLs are still used for the receive destuffmg circuitry. This paper describes a method of applying a complete second‐order digital phase‐locked loop (PLL) to a stuffing synchronization system. In the PLL used for the stuffing synchronization systems, a buffer memory consisting of an N‐stage frequency divider is provided in order to suppress jitter.This paper analyzes first the effects on the DPLL resulting from the incorporation of an N‐stage frequency divider based on a multilevel quantized phase comparator. The characteristics parameters of the complete second‐order DPLL when the N‐stage frequency divider is added are determined. Significant low‐frequency jitter is present in the narrow‐band complete second‐order DPLL. The phenomenon of low‐frequency jitter generation is analyzed and procedures for determining the coefficient values of the complete second‐order DPLL that will result in tolerable levels of low‐frequency jitter are described. Finally, the DPLL parameters are evaluated theoretically and experimentally to determine the suitability of the DPLL design for stuffing synchronization systems.