bluuebunny/crossref_metadata_2025_split huggingface dataset:
ATM switching network with route‐associated buffers and its traffic‐handling characteristics
Authors: Han Chimoon , Akiyama Minoru 
Published: July 2007

AbstractAsynchronous transfer mode (ATM) switching is studied widely as the switching method in the broadband ISDN and numerous switching methods have been proposed. In most of those methods, the deterioration of the throughput due to the internal collision of the cells is prevented in the switching network by a complex control protocol or by increasing the internal speed. In the highspeed broadband switching system such as ATM, however, it is desirable for the system that the structure and the control be simple, the internal speed not be increased, and the highly efficient switching network be realized with a nonblocking property.This paper attempts to satisfy the forementioned requirements and proposes the route‐associated buffer system in which the buffers are provided corresponding to the input and the output route, while improving the efficiency of the use of the buffers. The network configuration and the traffic control process are presented.In the traffic analysis, the poling model is defined, where the number of cells to be taken out from the individual buffer is adjusted according to the number of waiting cells. The traffic processing performance of the switching network is analyzed using the approximate method of analysis for the cyclic multiple queues. The usefulness of the method is shown by numerical analysis and simulation.
Direct sequence/spread spectrum communication systems sending with reference pn sequence for power line data transmission
Authors: Tachikawa Shin‐Ichi , Marubayashi Gen 
Published: July 2007

AbstractThis paper proposes a novel direct sequence/spread spectrum communication system for use in power line data transmission where the transmission characteristic varies largely and rapidly. In the proposed system, two similar PN sequences are used, one of which is loaded with data and the other is used as a reference PN. Waveform distortion during transmission can be cancelled out by an appropriate process utilizing two PN sequences. Data can be recovered as the sign of correlations between two PN sequences at the receiver. Results of computer simulation show considerable improvement in the data error rate over the conventional DS/SS system.
Antenna performance evaluation with reflector distortion data using Akima's interpolation scheme
Authors: Itanami Takao , Kobayashi Takehiko , Ohata Kohei 
Published: July 2007

AbstractAs multibeams begin to be used in satellite communication, the satellite‐borne antennas have become larger. Hence, development of an antenna with a large aperture with a lightweight and high surface accuracy is being carried out. Unlike conventional small antennas, this antenna experiences a large thermal deformation due to severe environmental conditions on the geostationary orbit. In addition, a large deformation due to gravity occurs in the performance confirmation test on the ground. In the development of such a large antenna, it is indispensable to develop a method to appropriately evaluate the change of electrical performance by the deformation.In this paper, an antenna characteristic computation method is presented which can compute the radiation characteristics of the reflector surface for arbitrarily deformed shapes. The present method uses Akima's interpolation scheme for the deformation data so that data needed for computation of the radiation characteristics are obtained and highly accurate computations are realized.The analysis results of the deformation of the reflector surface of a reflector by a general‐purpose structural analysis program (NASTRAN) is linked to the present computation method so that the variation of the antenna electrical performance by deformation is obtained and the results of the present method are presented. Further, it is shown that the measured antenna characteristics and the numerical results of the electrical performance by the reflector surface measurement data agree well. Hence, the present antenna characteristic computation method is extremely useful for the evaluation of the antenna characteristics.
Wide‐band characteristics of fin ferrite electromagnetic wave absorber
Authors: Naito Yoshiyuki , Mizumoto Tetsuya , Nose Hiroyuki , Takahashi Michiharu 
Published: July 2007

AbstractFin electromagnetic wave absorbers are proposed in which the sintered ferrite plates are placed in the direction perpendicular to the electric field of the incident electromagnetic field. By numerical calculations, it is shown that this structure has a broadband reflection suppressing characteristic. The characteristics of the absorbers in terms of the structural parameters of the absorber and ferrite permeability are shown, and it is found that the optimum structure of the absorber for a broadband operation depends on the permeability of the ferrite. Further, by means of the model experiment, the broadband characteristics of the proposed absorber are demonstrated.
Analysis of the pyramid electromagnetic wave absorber‐an approximated model and its application of TE wave
Authors: Anzai Hiroki , Saikawa Makoto , Mizumoto Tetsuya , Naito Yoshiyuki 
Published: July 2007

AbstractNo detailed analysis has been available on the return loss characteristics of a pyramidal electromagnetic wave absorber. Therefore, an approximate analysis method for the pyramidal absorber has not been established in a rigorous sense.In this paper, the return loss characteristics for the normal incident on the pyramidal absorber are derived by the numerical simulation based on the spatial network method. Also, as an approximate method for the wave absorber that can approximate the obtained results well, a method called the synthesized capacitance model is proposed. By comparison of the numerical results by the two methods, it is found that the approximate results by the synthesized capacitance model provide more accurate results than those by the previous approximate models. Further, by means of the synthesized capacitance model for the normal incidence, the oblique incidence characteristics of the TE wave were computed and the results agreed well with the measured data.
Method of estimating bit error due to lightning surge taking into account arrester operation
Authors: Motomitsu Tamio , Yamane Hiroshi , Hattori Mitsuo , Tokuda Masamitsu 
Published: July 2007

AbstractThe bit errors caused by the lightning surge contain one triggered by the operation of the lightning arrester installed in communication equipment and one caused by the superposition on the signal voltage the lightning surge (transverse lightning surge) appearing between two conductor wires due to the unbalance of the telecom system. In this paper, a method of estimating and evaluating the bit error by simulation (numerical calculation) is proposed in which these two bit errors are taken into account. By means of the proposed method, the average bit error per thunderstorm day by the lightning surge in the subscriber terminal of the AMI bit digital transmission system was derived. It was found that the bit error due to the operation of the arrester is proportional to ‐1.8 power of the operating voltage of the arrester while the bit error due to the transverse lightning surge is proportional to ‐1.8 power of the threshold level. The bit error at the time of appearance of the lightning can be substantially larger than the bit error inherent to the digital transmission system. Further, the relationship between the number of samples used in the simulation and the estimation error was studied. It was found that the adequate number of samples is 50 to 100.
Neural processing‐type optical wavelength division multiplexing demultiplexer using a grating
Authors: Aisawa Shigeki , Noguchi Kazuhiro , Matsumoto Takao , Tsunetsugu Hideki , Yuda Masahiro 
Published: July 2007

AbstractA neural processing‐type optical wavelength division multiplexing (WDM) demultiplexer (NP‐ODEMUX), which consists of diffraction grating, detector array, and neural network LSI, is proposed in order to improve receiver sensitivity while maintaining flexible demultiplexing characteristics. In previous work, a neural processing‐type optical WDM demultiplexer using a multimode optical waveguide was proposed. This conventional NP‐ODEMUX and the proposed grating‐type NP‐ODEMUX are compared using power penalty calculation simulations. The results show that receiver sensitivity is improved using the proposed grating‐type NPODEMUX.Also, a standard diffraction grating demultiplexer without neural processing is compared with the proposed NP‐ODEMUX using power penalty and it is shown that the proposed NP‐ODEMUX can demultiplex WDM signals without degrading receiver sensitivity. Next, the results of the demultiplexing experiment for six‐channel WDM signal which has been directly modulated at 150 Mb/s using nonreturn to zero (NRZ) pseudorandom signal by grating‐type NP‐ODEMUX prototype are described. Bit‐error rate measurement for both the conventional diffraction grating demultiplexer and the grating‐type NP‐ODEMUX using neural processing for the unequally spaced WDM signals revealed that the receiver sensitivity can be greatly improved and that it can flexibly compensate wavelength change.
A fair and efficient bandwidth allocation algorithm for high‐speed local area networks
Authors: Saito Tadao , Aida Hitoshi , Kim Byung‐Suk , Aoki Terumasa 
Published: July 2007

AbstractWith the advent of broadband integrated services digital network (B‐ISDN), there is the increasing need for high‐speed multimedia systems also in the area of local area networks (LANs). It is obvious that the conventional systems such as CSMA/CD or token ring cannot cope with those requirements. At present, several new access control methods are proposed for slotted ring (or bus) LANs suited to transmission rates above 155 Mbps.This paper reviews the characteristics of those methods in a systematic way and proposes a new access control method called distributed reset algorithm (DRA). DRA can provide high throughput while maintaining the almost strict access fairness by using a new control called “access bit control” in addition to the already known window control.
A new access control method based upon frame addressing for distributed access subscriber network
Authors: Saito Tadao , Aida Hitoshi , Kim Byung‐Suk 
Published: July 2007

AbstractA distributed access network in which the optical fiber is shared among terminals through media access control has been examined as the subscriber part of broadband integrated services digital network (B‐ISDN). In a distributed access subscriber network, unlike peer‐to‐peer communications which can be seen in local area networks, the main traffic flows are between exchange node and terminals. Therefore, a new access control scheme based on this characteristic should be developed. In this paper, a new access control method based on frame addressing is proposed and simulation analysis is performed. Compared with other methods, it is shown that, by employing cyclic reset and back‐pressure mechanism into the access control, a fair and efficient network access can be achieved for various types of traffic.
Transient model of wafer temperature in a furnace for semiconductor fabrication process
Authors: Mokuya Kinji , Matsuba Ikuo , Matsumoto Kuniaki , Yoshinaka Akira 
Published: July 2007

AbstractThe nonuniform temperatures that develop over silicon wafers on insertion and removal from the furnaces used in the oxidation and diffusion processes of semiconductor fabrication are one factor in reduced yields. For example, because of temperature differences in the oxidation process there are thermal stresses and differing thermal hystereses over the wafer surface which degrade the uniformity of the oxide layer formed. The most pronounced temperature differences, occurring when the wafers are inserted into the furnace, develop mainly because of the effect of the boat jig which supports the wafers. Since the heat capacity of the boat is much greater than that of the wafers, during the slower rise in the boat temperature radiant heat exchange with the wafer bottoms keeps the temperature of the bottoms lower than the temperature of the wafer tops, which are almost unaffected by the boat. This transient in the wafer temperature depends on such process parameters as the boat insertion speed, the ratio between the wafer and furnace reactor tube diameters, and the wafer spacing. In order to analyze this temperature characteristic the process is modelled and the results of numerical simulation are compared with experiment. The model for the wafer temperatures inside the furnace is a system of coupled partial differential equations for the mostly radiant heat fluxes of the boat and wafers. With an insertion speed of 2 m/sec, both the experimental data and the model give a maximum temperature difference over the wafer surface of 230°C near the end of insertion, thus confirming the model.
A novel Bi‐CMOS technology with upward and downward diffusion technique
Authors: Sato Kazuo , Shimizu Keiichiro , Nakamura Yutaka , Okas Koji , Nakamura Fumihisa , Kimura Takeji 
Published: July 2007

AbstractA Bi–CMOS technology with novel upward and downward isolation diffusion is investigated. This new structure permits the simultaneous realization of high‐performance, high–density CMOS and bipolar devices on the same LSI chip, which is necessary for advanced digital and analog circuitry.Beginning with a preliminary buried diffusion, the upward and downward isolation diffusion technique forms the MOS transistor n‐channel region and the bipolar device isolation regions. Adoption of this technique permits simplification of the fabrication process while using only a thin epitaxial layer (α.5 μm). Thus, very small, high‐performance (fT × 1.5 GHz) bipolar devices are obtained. Further, since the CMOS structure has both n+ and p+ buried layers and polysilicon electrodes, the CMOS devices are very dense and their latchup immunity characteristics are improved (by a factor of 3 over the usual CMOS).
Cmos device model for accurate circuit simulation application
Authors: Sano Eiichi , Kimura Tadakatsu 
Published: July 2007

AbstractCircuit simulation programs with much higher accuracy than those presently available are required to achieve analog circuits with higher accuracy. For the simulation method which is a factor in determining the accuracy of circuit simulation, a charge‐oriented simulation method has been proposed and utilized effectively. On the other hand, in terms of a device model which is another factor, there has been no current and capacitance model consistent with the forementioned simulation method and available for submicron devices. This paper proposes a submicron CMOS device model which is used in the charge oriented circuit simulation to achieve higher‐accuracy circuit analysis. The features of this model are: (1) continuity of drain conductance at the pinch‐off voltage ensures accurate expression of the drain conductance which is especially important in designing analog circuits; (2) minority carriers in the pinch‐off region are considered to express accurately the current and capacitance characteristics in the saturation region. By comparing the drain current vs. drain voltage characteristics for 0.6 μm and 1.0 μm devices and the capacitance characteristics for a 0.8 μm device reported elsewhere it is shown that the calculated values are in good agreement with the measured values. Thus, our model is confirmed to be applicable to the high‐accuracy design of submicron CMOS circuits.
Fabrication of optical waveguides in soda‐lime glass by field‐assisted potassium ion migration and the index‐profile formation process
Authors: Sawa Shinnosuke , Ono Kazuo , Ryoshima Tadashi 
Published: July 2007

AbstractAn optical waveguide was formed by thermal diffusion or field‐assisted thermal diffusion of potassium ions (K+) into a soda‐lime glass. The refractive index profile could be estimated precisely by the diffusion equation. Assuming that the exchange between the potassium ions and the sodium ions in the glass takes place, the diffusion equation was derived. Next, the mutual diffusion coefficient was obtained by the measuring the potassium ion density profile by an x‐ray microanalyzer. Using the result, it was shown that the diffusion process of potassium ions in a glass matches the model for the diffusion equation, unlike the case of silver diffusion. In addition, it was also shown that in the case of fieldassisted thermal diffusion, the potassium density profile in the glass can be obtained by numerically solving the diffusion equation using the measured values of the diffusion coefficient and current density. Also, the refractive index profile can be obtained for an arbitrary diffusion time and temperature. This indicates that the waveguide of graded‐index through step‐index types can be fabricated by diffusing potassium ions.
Design for SMF laser diode module using thick lens
Authors: Kishimoto Ryozo , Sumida Masatoyo 
Published: July 2007

AbstractThis paper proposes a laser diode (LD) module using a thick lens. Its configuration and characteristics are discussed. First, to clarify a design guideline of practical accuracy required in fabrication and to establish a design method for a low‐loss LD module, a single‐mode fiber (SMF) focused beam optics using a thick lens is analyzed via the beam mode expansion method. Next, coupling experiments were carried out to prove the validity of the theory. At the same time, a low‐loss coupling system has been realized in which the coupling loss is approximately 3.8 dB. Further, the off‐axis characteristics and the off‐axis tolerance were tested for LD's, lenses and single‐mode fibers. It is found that the LD module using a thick lens can constitute a coupling system with a large off‐axis tolerance. Also, this system has a low insertion loss, and the characteristics are stable against the external variations.
Semiconductor device simulation method using boundary‐fitted curvilinear coordinates and the voronoi discretization
Authors: Tago Kazutami 
Published: July 2007

AbstractA semiconductor device simulation method using boundary‐fitted curvilinear coordinates and the Voronoi discretization has been developed. In this method, arbitrary curved surfaces can be expressed exactly and easily using geometrical modeling techniques in computer graphics, while curvilinear coordinate points are generated automatically by numerically solving grid‐generation equations. The boundary conditions of the grid generation can be selected from among the following four conditions: (1) fixed boundary, (2) orthogonality, (3) smooth connection of the coordinate lines, and (4) control of concentration and intersection angles between the boundary and coordinate lines. Further, grid points can be concentrated at an arbitrary local region within the whole area. Thus, through control of the grid‐point configurations, improvements in accuracy of the calculation of the physical quantities may be achieved. In discretization of the Poisson and current continuity equations with curvilinear grids, a discretized formula as simple as in the finite difference method with the rectangular grids is developed, using the Voronoi polyhedron at each grid point as the control volume. The accuracy of current conservation is improved by more than four orders of magnitude over the ordinary boundary‐fit method. The simulation method is applied to an isolation passive MOSFET, and the solutions are confirmed to be stable under a bias of 5 V at the drain. An application to a bipolar transistor shows simulations are possible in which the impurity profiles are considered accurately.
Parallel operation of peak–current–controlled forward–type DC–DC converters
Authors: Sato Terukazu , Nakano Tadao , Harada Koosuke 
Published: July 2007

AbstractThe dc‐dc converter with peak‐current control has the following features, compared with the traditional type: (1) the output voltage is affected less by the input voltage variation; (2) it is easy to protect the circuit from the overcurrent due to output short‐circuit, etc.; (3) the power sharing is easy in the parallel operation of converters. Especially, the feature for the parallel operation is interesting from the viewpoint of high‐power, high‐reliability supply. However, the quantitative analysis has not been made for this property. As a typical case of parallel operation, this paper considers the parallel operation of two forward‐type converters with peak‐current control. The static and dynamic characteristics as well as the stability are analyzed for the case where the circuit is used as the constant‐voltage supply with feedback. The result of analysis agreed well with the result of experiment. The condition for power sharing is derived. The result can easily be extended to the case of N converters and provides a guideline for the design of the parallel operation.
Effect of plasma properties on the preparation of tin oxide thin film by means of DC planar magnetron plasma CVD
Authors: Fujita Hiroharu , Ueno Hironobu , Nagano Masamitsu , Matsuo Hisao 
Published: July 2007

AbstractThere have been many recent studies on thin‐film deposition in plasma. However, only a few reports have considered the relation between the film deposition and plasma characteristics. In this study, the influence of the plasma characteristics on the thin‐film deposition was investigated via the dc planar magnetron plasma chemical vapor deposition (CVD) technique. Assuming that the characteristics of inert gas plasma measured by probes are the same qualitatively as those of reactive gas plasma, tinoxide thin films which have been used for transparent electrodes, gas sensors, and so forth, are deposited. The decomposition of source materials is accelerated in the highdensity plasma region where the thin films deposited, are composed of highly densified particles and have a crystalline structure. The electrical conductivity of these films is higher than that of films formed in a low‐density plasma region.
Direct formation of solder bump on Al pad using ultrasonic soldering
Authors: Inaba Michihiko , Iwase Nobuo , Hirata Seiichi , Gonda Makoto , Imai Yasuhiro 
Published: July 2007

AbstractAlthough a conventional solder bump formation on Al pad uses an evaporation of Pb and Sn on the underlying metal (Au/Cu/Cr, Au/Pt/Ti, etc.) and reflow, it has the disadvantages of high equipment cost and complex process. By applying an ultrasonic soldering technique, in this work, solder bumps were formed directly and selectively on an Al pad without underlying metal. The sample chip used in the experiment had 118 Al pads which were 1.5 μm thick and 100 μm□, and anticorrosive Sn‐37 Pb‐5 Ag was used as a solder. By examining the factors affecting the bump formation percentage, an optimum condition was selected [(1) chip preheating temperature: above 280°C; (2) solder temperature: 280°C; (3) distance between chip and ultrasonic horn: ≈︁0 mm; (4) dip time: more than 8 s; (5) ultrasonic power: more than 135 W]. Using this condition, bumps were formed without damaging the passivation film, which was also the case on 30 μm □ pads with 50 μm pitch without bridging. The bump height was approximately 36 μm on 100 μm □ pads with a variation of ±6 μm. Since the shear force of the bump was on the average 32.5 g and all the breakage occurred within the bumps, a strong adhesion at the interface is guaranteed. The interface contained a compound several 1000 Å thick with a 4 : 1 composition of Al and Ag.