bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lens applicator for localized microwave hyperthermia
Authors: Nikawa Yoshio , Miyashita Teruo , Mori Shinsaku , Kikuchi Makoto , Sekiya Tomio 
Published: July 2007

AbstractHyperthermia is now recognized as an effective means for cancer therapy, and many reports on the irradiation of biological subjects by electromagnetic waves to produce dielectric heating and hyperthermia have been reported. Although it is desirable in hyperthermia selectively to heat the cancer tissue, it is difficult to estimate the heat distribution in the subject owing to insufficient analysis of the electromagnetic field distribution in the irradiated subject. At present it is not yet possible to control the temperature distribution in the biological subject. In electromagnetic wave hyperthermia, microwaves are effective from the viewpoint of efficiency or selective heating. On the other hand, it is difficult to heat a cancer in deep tissue because of reduced penetration of the microwaves into the subject. This paper shows experimentally and by theoretical analysis, using a microwave lens geometrically designed to produce a focused cylindrical wave as the applicator, that selective heating is possible for tissue 10 to 40 percent deeper than with planar wave. It is shown that the microwave lens applicator is effective for the heating of biological tissues.
A new method of circuit analysis and central trees of a graph
Authors: Kajitani Yoji , Kawamoto Tatsuya , Shinoda Shoji 
Published: July 2007

AbstractAs a method of analysis for the general linear lumped circuit including active elements, this paper proposes a new method called the primal dual analysis, in which the backward parts of the cut‐set and tieset analysis are applied in two steps. the problem to determine the minimum number of independent variables for the analysis is formulated from the graph‐theoretic viewpoint. the essential difference between the proposed method and the traditional methods is described from the viewpoint of minimizing the required set of variables. In the case of passive circuits, the problem of determining the minimum independent variables in the primal dual analysis is seen to be reduced to the problem of determining the central tree of the graph. This problem is known to be difficult to solve. In the latter part of this paper, some results for this problem, obtained by the authors up to present, are described.
Usage characteristics of detour routes in store‐and‐forward switching networks
Authors: Komatsu Masaharu , Mayeda Wataru 
Published: July 2007

AbstractThis paper discusses characteristics of detour routes in store‐and‐forward switching networks for the traffic route assignments one of which is obtained by the optimum route assignment theorem and the other the equal delay principle when message length is generally distributed. the optimum route assignment theorem gives necessary and sufficient conditions for the route assignment to have minimum average message or packet delay‐time over a whole network. the equal‐delay‐principle, which is widely employed in traffic control, can be considered as a theoretical base for determination of an adaptive route using estimated delay‐time. Both traffic assignments obtained by the optimum route assignment and equal delay principle use detour routes to reduce the delay caused by increase of traffic rate. This paper shows that regardless of line capacities and message (or packet) length distribution, the case of the optimum route assignment employs detour route at the smaller traffic rate than equal delay principle. Furthermore, this paper chooses one‐stage parallel route model to show how line capacities and coefficients of variation of message length influences usage of detour routes for these two methods.
A 64Kbit MOS dynamic RAM with auto/self refresh functions
Authors: Yamada Michihiro , Taniguchi Makoto , Kobayashi Toshifumi , Kumanoya Masaki , Nakano Takao 
Published: July 2007

AbstractUntil now, a refresh operation, which is necessary in using MOS dynamic RAMs, has made MOS dynamic RAMs more difficult to use compared with static RAMs. On the other hand, with advances in MOS dynamic RAMs, new refresh modes, i.e., automatic and self refresh modes, become available when a spare pin is applied to a refresh control signal. In 64Kbit MOS dynamic RAMs, pin 1 can be such a refresh control terminal if the substrate bias is generated on‐chip. Circuit considerations in accommodating the automatic and self refresh modes by pin 1 are discussed, with special attention given to the on‐chip refresh address counter and the timer used during the self refresh. A practical 64Kbit MOS dynamic RAM has been realized with the chip area increase of 1.6% and the standby current increase of 0.3 mA as the result of implementing the automatic and self refresh modes.
Differential detection of manipulated MSK signals with decision feedback
Authors: Kurokawa Akira , Yamada Takahiro , Harashima Hiroshi , Miyakawa Hiroshi 
Published: July 2007

AbstractThe types of manipulated MSK (Minimum Shift Keying) signals obtained by narrowing MSK band which are currently attracting attention include TFM (Tamed Frequency Modulation) and GMSK (Gaussian filtered MSK) signals. A new 2‐bit delay differential detection technique for these manipulated signals is proposed and its performance is compared with the conventional technology. In the proposed technique, a decision feedback circuit which controls the phase references of the delayed signals is used to reduce the intersymbol interference caused by the transmit and receive filters. the proposed technique is especially effective for manipulated MSK signals. Computer simulation results show that the proposed technique requires a smaller receive filter bandwidth and the bit error performance results in an improvement of 3 to 8 dB in the SN ratio compared with the conventional technique.
Mathematical expression of the load characteristics of microwave oscillators and the injection‐locking characteristics
Authors: Fukumoto Katsumi , Nakajima Masamitsu , Ikenoue Jun‐Ichi 
Published: July 2007

AbstractMost studies of the behavior of oscillators are based on the oscillator model proposed by Van der Pol. This model, however, is inadequate for a detailed description of the load characteristics and injection‐locking operations of actual oscillators. an oscillator model is proposed which represents the load characteristics of actual oscillators much better than does the Van der Pol model and a method is presented for determining the parameters of this model. Using this model, the injection‐locking operation of a microwave oscillator based on the concept of a traveling wave is analyzed and a relation between the load characteristics and the injection‐locking characteristics is derived. This study serves as an example of evaluating the validity of the oscillator model used in the analysis. It would be possible to represent the oscillator characteristics with a few numerical values (as in FET's and transistors). the theory and analytical results are confirmed experimentally.
Multistructured optical IC elements by polymer thin films
Authors: Kato Isamu , Komatsu Masatoshi 
Published: July 2007

AbstractConventional thin film optical elements consist of optical waveguides placed transversely in one plane. A new type of multilayer optical circuit element consisting of stacked thin‐film optical waveguides is proposed using polymer films in which optical waveguides are formed by ultraviolet light. After fabrication of an optical waveguide, the resistivity to solvent of the thin film increases, and hence any number of layers can be stacked without affecting the lower layers. We fabricated two‐layer and three‐layer optical directional couplers. In the former, optical waveguides are created in each layer such that they cross to each other. In the latter an additional layer is inserted between the two layers containing the waveguides. the optical coupling in these directional couplers takes place in the direction of the film thickness. the film thickness of the middle layer is measured, and the dependence of the coupling coefficient on the crossing angle and the middle layer thickness is studied experimentally. It is pointed out that an optical directional coupler with an arbitrary degree of coupling is easily fabricated. Also studied are n‐way optical equal parts dividers.
Cancellation techniques of co‐channel interference in asynchronous spread spectrum multiple access systems
Authors: Kohno Ryuji , Hatori Mitsutoshi 
Published: July 2007

AbstractA spread spectrum multiple access (SSMA) communication scheme employing asynchronous code‐multiplexing technique has been used in both mobile and satellite communication systems. One shortcoming of the SSMA system is the co‐channel interference due to the correlations among the pseudo noise (PN) sequences being used by multiple channels. Such co‐channel interference in the reception limits the number of channels that can share one common frequency band. Furthermore, there is a distant‐dependent problem of different received‐powers from different transmitters.This paper describes a technique for cancelling the co‐channel interference in asynchronous SSMA systems. This technique does not treat the co‐channel interference as thermal noise. It considers the co‐channel interference as components that can be recreated at each receiver. If the correlations among the PN sequences of all the active channels become known, the co‐channel interference can be cancelled using the linear algebraic approach. As a result, a larger number of channels can share the same frequency band more efficiently. Further, if initial synchronization can be implemented then the distant‐dependent problem can be alleviated.
A K/C/S bands satellite antenna with frequency selective surface
Authors: Ando Makoto , Ueno Kenji , Kumazawa Hiroyuki , Kagoshima Kenichi 
Published: July 2007

AbstractAK(30/20 CHz)/C(6/4 GHz)/S(2.6/2.5 GHz) bands offset satellite antenna with anS/Cbands feed horn and a low pass frequency selective surface (FSS) covering only part of a whole aperture angle, is designed, reproduced, its characteristic as an onboard antenna is confirmed and a design method and characteristic evaluation method for this type of antenna are established. In this antenna, three different frequency bands with different optimum aperture diameters share one reflector. the optimum aperture diameters peculiar for respective frequency bands (1.8 m forS, 1 m forC,Kbands) are realized equivalently by choosing the diameter of theS/Cbands feed horn and the size of FSS. the decrease in service area edge gain due to frequency bands sharing is about 1 dB, a satisfactory result compared to the case in which respective frequency band antennas are on board. the efficient analysis method assuming equivalent currents on the plane containing the FSS is derived to evaluate scattering from the small FSS. This method permits an antenna design with FSS size as a parameter; this was not considered before. the design and analysis of the antenna are confirmed by measurements.
Design and operation of a high‐speed bubble memory board
Authors: Toyooka Takashi , Sugie Mamoru , Aoki Hirokazu , Imura Ryo , Sugita Yutaka , Yoshizawa Shigeru , Ishida Kazuhiro 
Published: July 2007

AbstractA magnetic memory board was designed and an experimental model was constructed for evaluation of its characteristics. the memory board contains eight 256 kb memory chips with an 8 μm cycle and operates with a rotating magnetic frequency of 312.5 kHz. These chips are driven by an already‐developed single‐chip memory module and a high‐speed rotating magnetic field drive circuit. to improve the peripheral circuits with respect to speed, reliability and size, several circuits were developed, including the transformer‐coupled pulse‐current generator for the functional part of the chip, the sense circuit with a high‐sensitivity comparator, and the high‐speed defect loop skip circuit using ROM and a shift resistor. the eight memory modules and their peripheral circuits were implemented on a 24.5 × 48.5 cm memory board. the circuits were adjusted and an examination was made of the defect loop detection and the operational margin, which indicated that stable operation was possible. Evaluation of the experimental memory board over a temperature range of 10° to 45° showed that the bias margin is larger than ±5 Oe, the rotating magnetic field amplitude margin is larger than ±6 Ue, and the pulse current phase margin is greater than ±150 as. the memory board was applied to the 64 Mb file in the database machine.
Self‐excited oscillation and monostable operation of a bistable light emitting diode (BILED)
Authors: Okumura Kenichiro , Ogawa Yoh , Ito Hiromasa , Inaba Humio 
Published: July 2007

AbstractA new simple opto‐electronic bistable device has been obtained by combining a light emitting diode (LED) and a photodetector (PD) with electronic feedback using a broad bandpass filter. This has interesting dynamic characteristics which are expected to have such various applications as optical oscillators, optical pulse generators and optical pulsewidth modulators. the dynamic characteristics are represented by secondorder nonlinear differential equations. In the analyses of these nonlinear systems, instead of numerical analyses with a computer, an approximate analytical method devised for this purpose has been used. This method has been used for investigating the characteristics of the proposed device quantitatively. These include the frequency of oscillations, pulsewidths and hysteresis. the results of the analyses agree approximately with experimentally observed values, thus the dynamic characteristics of the proposed device can be explained.
Waveguide applicator with convergent lens for localized microwave hyperthermia
Authors: Nikawa Yoshio , Iwamoto Masanobu , Mori Shinsaku , Kikuchi Makoto 
Published: July 2007

AbstractIn the treatment of cancer by hyperthermia, it is desirable that the heating of the biological object be performed locally as noninvasively. For such a purpose, dielectric heating by electromagnetic wave presently is considered. the study of the design of the antenna (applicator) for local heating of a deep portion of the body is still in its infancy. This paper investigates a deeper penetration of the electromagnetic wave into the body, and proposes a convergent lens‐type waveguide applicator, where a metallic lens filled with dielectric material is attached to the waveguide. A heating experiment was performed using the proposed applicator at 2450 MHz for the phantom models consisting of a muscle singlelayer and muscle‐fat two‐layers, with electrical and thermal constants equivalent to those of biological tissues. Then the temperature distribution inside the model was examined in two dimensions using liquid‐crystal film. As a result, it is seen that by using the convergent waveguide applicator, the electromagnetic wave penetrates into the body by 40% more than in the case of traditional simple waveguide applicator, resulting in deeper heating. Furthermore, using the surface cooling device proposed for the applicator, it is verified that the local heating required in the hyperthermia can be realized.
Parasitic effects and polarization diversity of archimedean spiral antenna
Authors: Nakamo Hisamatsu , Yamauchi Junji , Sugiyama Yutaka 
Published: July 2007

AbstractFor the purpose of controlling the polarization of an Archimedean spiral antenna (SA), a parasitic spiral element is added on the same plane of a two‐wire SA. the radiation characteristics have been studied numerically and experimentally. First, the current distributions on both the active and parasitic elements are calculated from Hallen‐type integral equations in the frequency range of 3 to 6 GHz. Comparing the current distributions with those of a two‐wire SA and a four‐wire four‐terminal fed SA, we study the mechanism of polarization control. It is found that the present antenna operates as a linearly polarized element at lower frequencies and a circular polarization element at higher frequencies. It is found also that the input impedance does not change appreciably in frequency and hence the broadband nature of the conventional two‐wire SA is retained. Finally, it is confirmed numerically that circular polarizations in the opposite sense can be obtained over a wide range of angle due to change in excitation phase when four arms are excited.
Energy trapping of backward‐wave width‐extensional vibrations in piezoelectric strips and its application to filters
Authors: Watanabe Hiroshi , Shimizu Hiroshi 
Published: July 2007

AbstractFor the purpose of extending the useful range of trapped‐energy resonators and filters up to the middle band less than a few MHz, the energy trapping of the width‐extensional vibrations in a thin piezoelectric strip is studied. Since the width‐extensional vibration exhibits a dispersion characteristic of the high‐cut type in most piezoelectric materials, the backward‐wave energy trapping needs to be applied. As realistic methods, two approaches are discussed. In one of them, the areas on both sides of the excitation part at the center of the strip are short‐circuited by the electrode. In the other method, this portion is made unpolarized. In each approach, the energy trapping of the width‐extensional vibration is realized if the electrode in the excitation part is made a partial electrode with its width narrower than the strip width. A clean resonant response with few unwanted modes is obtained. A method for fabrication and experimental results are reported for a ladder filter and a single‐mode three‐terminal filter. Effectiveness of this device for a filter in the middle band is indicated.
I2L device circuit model with layout patterns
Authors: Shinmi Toshio , Inohira Susumu , Nagata Minoru , Hosono Etsuo , Iida Kyoichi , Furihata Makoto 
Published: July 2007

AbstractAn algorithm for CAD simulation model is discussed for an I2L circuit important for a bipolar analog‐digital hybrid LSI. A versatile modeling method is proposed here in which variation of the planar pattern of the I2L circuit is included. In this method the I2L device is divided into the injector, base electrode, collector and base termination. Each section is modeled by lumped elements consisting of transistors, diodes and resistors. the model parameters are expressed in terms of the main current density and main carrier concentration density of the I2L device. From this model, the terminal current and the carrier transit time can be related to the device shape. the terminal voltage dependence of the terminal current and the terminal current dependence of the gain bandwidth product as simulated by this method agreed within 10% with the measured values in the practical range (injector current 1 ‐ 100 μA). As an example of the application of this method to the I2L circuit, the injector current level dependence of the delay time of the 5‐stage ring oscillator and the usable current range vs. the input frequency of the 10‐stage counter are calculated and the simulation values agreed with the measured data within 10%.
Piezoelectric ceramic resonators using edge‐mode vibration
Authors: Iseki Yuji , Watanabe Hiroshi , Shimizu Hiroshi 
Published: July 2007

AbstractTo obtain miniaturized resonators with ease of support in the medium frequency range below several megahertz, piezoelectric ceramic resonators using the edge‐mode (the mode of vibration whose energy is confined to an edge of a thin strip) have been investigated. the theoretical analysis of the edge‐mode in a thin semiinfinite strip whose resonant frequency depends on its width has been carried out, and the characteristics of the edge‐mode, i.e., the resonant frequency, the distribution of displacement, and the distribution of planar dilatation, have become clear. In order to excite the edgemode vibration efficiently, three types of electrodes have been proposed which have envelopes matched with the distribution of planar dilatation. the optimum dimensions of the electrodes have been determined from the calculated results for capacitance ratios. Some piezoelectric edge‐mode resonators have been fabricated using Pb (Zr, Ti)O3 ceramics. It has been confirmed that resonators of this type have a small capacitance ratio between 20 and 40 approximately, frequency responses free from unwanted modes over a wide frequency range, and ease in mechanical support.
A study on SAW voltage‐controlled‐oscillator using a method of vector summation
Authors: Saito Shigeki , Urabe Shuuji 
Published: July 2007

AbstractTo achieve ultraminiaturization of synthesizers used in mobile radio this paper proposes the use of a SAW‐VCO incorporating a vector summation technique and describes studies regarding the important parameters of frequency purity and wide‐range variability. the SAW‐VCO using the vector summation method would be composed of SAW elements and a variable gain circuit and it can be expected that they would be ultraminiaturized (using monolithic IC technology). This paper focuses on the issues of high purity and wide‐range frequency variability considering the effect that the SAW delay line has on oscillation characteristics and examines, both experimentally and theoretically, the effects that amplitude ripple has on noise characteristics. In experiments in the 800‐MHz band, a frequency variation range of about 0.5% and C/N of 67 ∼ 75 dB were obtained (C is the carrier power and N is the noise in an 8‐ kHz band with 12.5‐kHz detuning).
Application of least‐squares method to adaptive channel equalizer with frequency sampling filter
Authors: Fujii Tetsoru , Harashima Hiroshi , Miyakawa Hiroshi 
Published: July 2007

AbstractThis paper presents a new design method for a frequency sampling adaptive equalizer using the least‐squares method and reports the results obtained in analyzing the equalizer performance. This system employs an adaptive equalizer configuration in which a cyclic code equal to the tap length is used as a test signal with the receive signal and the reference signal each undergoing a discrete Fourier transformation using a frequency sampling filter and applying the least‐squares method in a one‐to‐one relationship to each DFT coefficient. A condition for the implementation of this system is that the test signal be a cyclic code, but this system requires fewer arithmetic operations than any other system employing the least‐squares method. the system presented here employs a high‐speed convergence algorithm in the initial training period and after convergence is accomplished it switches to a gradient method using a frequency sampling adaptive equalizer. In simulation tests with telephone lines it was found that this equalizer converged in about one‐third the time required for the transversal adaptive equalizer.
Time spread transmission system using block conversion
Authors: Ohtake Kohhei , Ohue Kenji 
Published: July 2007

AbstractIn the digital transmission of non‐telephone signals, impulse noise interference, such as switching machine noise, interruptions, etc., become problematic and it has become necessary to suppress them. to suppress impulse noise interference efficiently, this paper presents a time spread transmission system, which transmits digital signals spread on the time axis through a block conversion, and discusses the system construction and the noise attenuation characteristic. First, the requirements for the time spread matrix in a general communication channel with impulse noises and random noises, such as thermal noise, crosstalk, etc., are described. It is clarified that for the matrix a cyclic orthogonal one is most suitable. For a single impulse noise interference, noise amplitude attenuation characteristics of the system are improved by 3 dB, compared with those of the conventional smearing‐desmearing filter method. Finally, the bit error rate is estimated for burst noise interference channel on a statistical noise model and it is shown that the bit error rate reduction of two decimals is achieved for the case of transmission rate 64 Kb/s and spread time 8 ms.