bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of a near‐field measurement to the characteristics verification of a polyhedron approximated antenna
Authors: Hanayama Eiji , Someya Suguru , Takano Tadashi 
Published: July 2007

AbstractIn most of the deployable antennas to be placed on board a satellite, the main reflector is made of planar facets or ruled surfaces. Therefore, an anomaly can be expected in the electric field distribution on the aperture in comparison with the smooth reflector. This paper presents the near‐field measurement method, relevant problems, and measurement results for a polyhedron approximated antenna with a reflector made of planar facets. The near‐field measurement system is of a polarplane scanning type, and the two polar components of the electric field can be measured simultaneously. With this system, the near‐field of the polyhedron approximated antenna is measured. It is experimentally shown that the amplitude is maximum at the junction of the facets; thus, the validity of the previously reported theoretical analysis is proven. Although the near‐field distribution depends on the measurement plane, the results of the transform of such a distribution to the far‐field by the aperture distribution method are identical regardless of the measurement plane. Further, reduction of the near‐field measurement points is discussed. In the case of the present antenna, it is shown to be necessary to use 30 points and 36 points, respectively, of the number of measurement points in the radial and circumferential directions with the measurement scan range at the circumscribing circle of the hexagonal aperture, if the far‐field paraxial radiation characteristics obtained are accurate to within 1 dB.
A packet‐generation model based on communication characteristics in an ethernet system
Authors: Ishida Yoko , Takahara Mikio 
Published: July 2007

AbstractSome communication characteristics of an Ethernet were measured and investigated for the purpose of creating a packet‐generating model for use in network characteristics simulations. The communication protocols measured were Telnet, X‐Window, NetWare, Apple Talk, and so on. The measured results showed some interesting characteristics for the generated packet‐length distribution and the packet‐generation spacing depending on the communication contents and the terminal types such as Server and Client terminals. Based on the measured data, a variable packet‐length generation model for use in network simulations is created. Some simulated results using the model are shown and differences between the variable and the fixed packet‐length models are investigated for the throughput characteristics.
Variable bit‐rate video transmission using traffic shaping
Authors: Inoue Masahiro , Kawashima Masahisa , Tominaga Hideyoshi 
Published: July 2007

AbstractVideo transmission that uses traffic shaping to smooth bit‐rate variations in performing a variable bit‐rate transmission while controlling congestion on an ATM network is examined. First, a traffic shaping system is proposed that keeps the transmission delay due to buffering under a fixed permitted value. Next, in simulation, the relationship between the effective bit‐rate smoothing of traffic shaping, the permitted delay, and effective congestion control are shown. Effective congestion control due to the use of average rate control in conjunction with traffic shaping is also shown. Effective bit‐rate smoothing and effective congestion control change in accordance with the size of the permitted delay. In an example experiment, an improvement in effective bit‐rate smoothing in a scene change is evident when the permitted delay increases in a segment of under roughly 100 ms and the rate increase is inversely proportional to the permitted delay.Consequently, saturation probability decreases. Even when the permitted delay is increased in a segment exceeding 100 ms, saturation probability decreases, although a decrease in the maximum bit rate is not evident due to smoothing. The effect of the two systems is multiplied if the average bit rate and traffic shaping are used together, with the saturation probability being greatly reduced.
Theoretical analysis of stoneley waves propagating along an interface between piezoelectric material and isotropic material
Authors: Irino Toshio , Shimizu Yasutaka 
Published: July 2007

AbstractConventional surface acoustic wave (SAW) devices mainly use Rayleigh waves that propagate on the substrate surface. Therefore, they require protective packaging and are expensive as well as unreliable. This paper reports an effort to develop SAW devices that do not require packaging. To this end we study the Stoneley waves propagating along the interface between the piezoelectric and isotropic materials. A range of material constants of isotropic materials is obtained which allows the Stoneley wave if combined with piezoelectric materials with various cuts and propagation directions. We obtain the relation of the allowable range to the maximum velocity of the Stoneley wave and the velocity of the Rayleigh wave. It is found that the Stoneley wave can be supported with a combination of glass and LiTaO3, PZT4 and ZnO. It is not possible to concentrate the energy near the interface if LiNbO3 and Bi12GeO20 are used.
Improved planar magnetron sputtering system and its application for deposition of ALN films
Authors: Takahashi Takakazu 
Published: July 2007

AbstractAn improved planar magnetron sputtering system was constructed, where a solenoid coil is placed surrounding the pyrex glass chamber. the magnetic field distribution, dc discharge and sputtering characteristics are investigated in detail with the dc current (IS) in the solenoid coil as the parameter. The magnetic field distribution was investigated by measuring the field along the target plane (B″) and the direction vertical to the plane (B⟂). The dc discharge and sputtering characteristics were examined in Ar or N2 with pressure of 0.08 to 3 Pa; Ti was used as the target. By setting IS so that B″ increases, the dc discharge voltage and spark voltage decreases and the dc discharge current increases. This tendency is more remarkable when IS is large. It was seen also that the erosion region of the target depends on IS. A reactive AlN film was fabricated by this system, and it was seen that the C axis orientation of the film depends on the kind of atmosphere gas. In N2, the orientation is vertical to the film plane and is parallel in NH3.
Optical fiber loss increase due to hydrogen and long‐term loss stability for optical fiber cables
Authors: Noguchi Kazuhiro , Shibata Nori , Uesugi Naoshi , Ishihara Koushi , Negishi Yukiyasu 
Published: July 2007

AbstractRecently, it has become clear that the long‐term loss of an optical fiber increases if the fiber is exposed to hydrogen. This phenomenon indicates that the loss in the optical fiber installed in a cable can increase if for some reason hydrogen is generated in the fiber cable. Therefore, this phenomenon is important for reliability design consideration. When the optical communication system with the 1.3 μm band is in actual use and the one with the 1.5 μm band is nearing its preparation for actual use, it is especially important to understand clearly the guarantee of long‐term reliability of an optical fiber cable and prevention of the effects of hydrogen. In this paper, the loss increase characteristics are formulated for optical fiber with germanium as an only dopant placed in a hydrogen atmosphere. The formulation is done from the results of increased temperature tests in hydrogen. From the formula, an allowable level of hydrogen pressure in the cable is calculated such that the loss increase of the fiber is kept below a specified value. It is also shown that the loss increase is sufficiently suppressed for practice by preventing water leakage into the cable.
Development characteristics of photoactive polyimide
Authors: Naito Noboru , Kakuda Nobuhiko , Wada Tsutomu 
Published: July 2007

AbstractDevelopment characteristics of photosensitive polyimide, which has been applied experimentally to insulation films for multilevel interconnection systems, were examined. Photoactive polyimide, photo‐neece reveals that the thickness of the film (even exposed areas) is reduced remarkably by its development despite the fact that the film is a negative‐type photoresist. It was found that the dissolution rate of the exposed areas by a development, not only depends on the conditions of the exposure but also on the conditions of prebaking. It was also found, notably in the prebake‐dependence of the dissolution rate, that the dissolution rate is determined by the thermal decomposition of the photoactive substance at a temperature above 80°C, and, by the obstruction of crosslinking reaction due to a residual solvent at a temperature below 80°C. The prebake‐temperature dependence of the dissolution rate of unexposed polyimide is determined by the quantity of residue on evaporation of the solvent, since the activation energy agrees approximately with the evaporation heat of solvent N‐methyl 2‐pyrrolidone.
Analysis of semiconductor multilayer and its application to surface emitting lasers
Authors: Morinaga Motoyasu , Chailertvanitkuls Anan , Iga Kenichi 
Published: July 2007

AbstractA dynamic‐single‐mode laser has become important as a light source for optical fiber communications using a 1.5 μm wavelength band, and a surface emitting laser is promising as one of them. However, a good ohmic contact must serve simultaneously as a mirror and it was difficult by a present technique to obtain a reflective mirror with high reflectivity. In this paper, we apply the multilayer heterostructure with the thick ness of quarter wavelength to the surface emitting laser reflector to solve the difficulty. First: (1) we analyzed the semiconductor multilayer DBR by expanding the multilayer film theory to calculate the complex field reflectivity r and obtained the power reflectivity R and the effective optical path length which is practically effective to the DBR laser. Then we clarify the lasing condition of the surface emitting laser using the semiconductor multilayer DBR.
Finite‐element solution for scattering of lamb waves by asymmetrically located discontinuities in an elastic plate waveguide
Authors: Hasegawa Koji , Koshiba Masanori , Suzuki Michio 
Published: July 2007

AbstractThis paper considers the scattering of Lamb waves due to the discontinuity of elastic plate waveguide. A method of analysis is presented which is a combination of the finite‐element method and analytical solution. The analytical solution is derived taking the cut‐off mode into consideration. Consequently, the region of application of the finite‐element method is reduced drastically compared with the traditional method of analysis by finite‐element method ignoring the cut‐off mode. In the past, the formulation has been made by restricting the discontinuities to symmetrical distribution in regard to the central plane of the plate. In this paper, this restriction is removed and discontinuities of any distribution in regard to the elastic plate can be handled. The effectiveness of taking the cut‐off mode into consideration is verified by applying the proposed method to the scattering of Lamb waves by a free‐edge of the elastic plate and by a slit which is symmetrical in regard to the central plane of the plate. As examples of discontinuities with asymmetrical distribution in regard to the central plane of elastic plate, a slit on one of the surfaces and wedge‐shaped crack are considered. The result of analysis is presented for the scattering characteristics when a fundamental symmetric Lamb wave or fundamental antisymmetric Lamb wave is incident.
Development of high‐performance flexible optical solar reflectors
Authors: Ichino Toshihiro , Sasaki Shigekuni , Hasuda Yoshinori 
Published: July 2007

AbstractAs communication satellites become larger, the flexible optical solar reflector (OSR) controls the temperature of satellites by reducing its weight and thus the assembly work becomes easier. FEP teflon film with vacuum‐deposited silver is a representative flexible OSR, but this deteriorates by radiations in space. This paper investigates the applications of poly(etherimide) (PEI) and poly(etheretherketone) (PEEK), which have excellent radiation‐resistance to the thermal radiation layer of an OSR. Various types of OSRs with PEI and PEEK were fabricated, and their thermal control properties electron‐radiation resistance and UV radiation resistance were investigated. Excellent properties of PEI with vacuum‐deposited silver (PEI/Ag) were confirmed. A new high‐performance flexible OSR, which is superior to FEP teflon with silver, was developed. The results are summarized as:
the initial thermal control properties are represented by the solar absorptance (α s) × 0.15 to 0.17, and the thermal emittance (ϵ) × 0.77 to 0.85; (2) the increase of αs, after an electron irradiation equivalent to 10 years in a geostationary orbit, is 0.01; (3) PEI/Ag can be electric‐conductive without degrading the original characteristics, by coating its surface with indium‐tin‐oxide; and (4) the increase of αs, after an UV irradiation equivalent to 2 years in a geostationary orbit, is 0.03. However, the increase of αs can be prevented by coating the surface with CeO2.
Numerical analysis of magnetization characteristics in the saturation region of magnetic circuits
Authors: Watanabe Hiroyuki , Kato Katsuhiro 
Published: July 2007

AbstractIn the design of such magnetic circuits as electromagnetic relays, it is important to determine how the magnetic body is magnetized by a driving coil and how the inductance seen from the driving coil is related to the shape and the material characteristics of the magnetic material. In this paper, the Newton‐Raphson method is applied to a combination of the analytical solution based on Green's function and the finite element solution. Magnetization characteristics including magnetic saturation are obtained for a magnetic body with a rotationally symmetric bar shape. The relation of the method of element division to the computational error and the computation time is studied first for the inductance of an ellipsoidal magnetic body for which the exact solution is known in the linear region. If the division is such that the dispersion of the magnetic energy in the element to be analyzed is less than 1.0, the inductance can be obtained with a short computation time and a small memory requirement while the error from the exact solution is less than 1.8 percent. Magnetic characteristics are obtained with the material characteristics of the material taken into consideration. A range is found in which the nonlinear solution can be approximated with a linear solution. Further, the present method is applied to a cylindrical magnetic body. It is shown that the nonlinear solution of the magnetization characteristics agrees well with the measured values.
Gas sensing characteristics of reactively sputtered SNO2 films
Authors: Kuriki Shinya , Sano Katsumasa , Konishi Hajime , Matsumoto Goro 
Published: July 2007

AbstractSensing characteristics to various flammable gases have been studied for SnO2 thin films made by RF reactive sputtering method. The film has reacted most selectively with ethanol among ethanol, carbon monoxide, hydrogen, methane and propane. The sensitivity is S × 0.5. From the x‐ray photoelectron spectroscopy for the SnO2 films fabricated under different conditions, it is found that there exists a close relationship between the oxygen content in SnO2 and the ethanol gas sensitivity. Conductance, carrier density and Hall mobility have been measured at various temperatures in several gas environments so that their relation to the gas sensitivity is studied. It is found that the variation of the conductance due to ethanol gas is caused by the variation of the electron concentration of the SnO2 film due to adsorption and desorption of oxygen. When very thin Pt is evaporated in islands on the surface of the SnO2 film, the ethanol gas sensitivity was increased as well as the sensitivity to carbon monoxide and hydrogen.
A multimicroelectrode fabricated by silicon dry etching
Authors: Takahashi Kohro , Shoji Shuichi , Matsuo Tadayuki 
Published: July 2007

AbstractIn neuro‐physiology, it is important to record neural impulses from the central neural system simultaneously. For this purpose, a silicon substrate which forms a multimicroelectrode was fabricated and a precise fabrication of a 10 μm thick microelectrode with a 30 μm wide tip was achieved by using Si dry etching. The high‐quality insulation of the electrode in a physiological solution was obtained by using Ta and high‐temperature CVD Si3N4. However, Ta itself is not adequate for the recording site because it is oxidized easily in an electrolyte causing the increase of the electrode impedance. Platinum‐black was electroplated on the titanium surface in order to stabilize and reduce the electrode impedance. The interelectrode crosstalk between electrodes and signal attenuation due to the parasitic capacitances were 0.4% and 4.4%, respectively.
Preparation and properties of Ba‐ferrite films by rf diode sputtering
Authors: Morisako Akimitsu , Matsumoto Mitsunori , Naoe Masahiko 
Published: July 2007

AbstractBa‐ferrite films were deposited by rfdiode sputtering which is one of the most conventional methods for complex oxide deposition and the applications of such films in perpendicular magnetic recording are discussed. Because of the bombardment by high‐energy particles, the composition of the deposited film was different from that of the target material. However, we were able to beam films with stoichiometric composition by adjusting the composition of the target. In one case, the first 300 Å layer had spinel‐type crystal structure and the layer above that initial layer had the structure of the magnetoplumbite type of Ba‐ferrite, oriented along the c‐axis. In the other case, the entire film was composed of the Ba‐ferrite layer oriented along the c‐axis. The result of investigating the growth conditions showed that the spinel layer caused a Δθ50 dispersion of the growth orientation in the Ba‐ferrite layer away from the c‐axis. When the growth temperature was around 550°C, the growth occurred in the direction of the c‐axis. The surface roughness of the film was dependent on the distance between the target and the substrate, the partial pressure of oxygen, and the substrate temperature. At high oxygen partial pressures, the deviation of the growth orientation from the c‐axis was especially high, and the surface became rough. The best Ba‐ferrite film had the following properties: Δθ50 = 2 to 3°, Hc1 = 1.2 kOe and Ms = 300 emu/cc. The film surface was smooth and hard enough to serve as a perpendicular magnetic recording medium.
Launching and receiving conditions for optical fiber loss measurements using an OTDR
Authors: Furukawa Shin‐Ichi , Koyamada Yahei 
Published: July 2007

AbstractOptical pulse measuring instruments (OTDRs) are very useful in locating broken areas and assessing the homogeneity of optical fibers, etc. Until now, the theoretical relation between the measured results of the optical and splicing losses of cut‐back and OTDR methods was not known and OTDRs were not used to measure losses of steady‐state mode distributions. This study investigates the backscattering mode distribution of graded‐index optical fibers using geometrical optics. The launching condition of the light pulse and the receiving condition of back‐scattering, and their relation to the measured optical and splicing losses, are determined. The theoretical and experimental relation between the measured values of backscattering by OTDR and cut‐back methods is also discussed. As a result, it is shown that the steady‐state condition of the received backscattering light is necessary when measuring the losses of steady‐state mode distribution by OTDR method. We propose the possibility of estimating the splicing loss values of the cut‐back method from the difference of the splicing loss measurements under varied launching conditions of OTDR method. Correctness of this method is confirmed experimentally. In this method, no previous preparation is required and by changing the launching conditions at only one end, only two measurements are made and a simple calculation is required. Therefore, it is expected that measurement efforts are significantly reduced by this method.
A 2 ∼ 18‐GHz band distributed MMIC amplifier with single supply bias network
Authors: Seino Kiyoharu , Takagi Tadashi , Ikeda Yukio , Ishikawa Takahide 
Published: July 2007

AbstractA design concept and experimental results are reported on a distributed amplifier with a flat gain characteristic. To obtain a broadband characteristic, the distributed amplifier is designed in such a way that the input power to each FET is as equal as possible. The obtained performances at 2 to 18 GHz are such that the gain is 7 ± 0.5 dB, the noise figure is less than 5.8 dB, and the VSWR is less than 2. In this amplifier, a self‐bias circuit is installed at the source electrode of each FET so that it can be operated with a single power supply.
Finite‐element solution of three‐dimensional resonator problems. Novel rectangular parallelepiped elements
Authors: Hano Mitsuo 
Published: July 2007

AbstractNew rectangular parallelepiped elements are proposed for analyses by finite elements for problems of three‐dimensional resonators. Earlier methods of finite‐element analysis confirmed the generation of nonphysical spurious solutions which are mixed with physical solutions. New first‐order and second‐order rectangular parallelepiped elements are proposed and the formulations of these finite elements are derived. One of the characteristics of these new elements is that tangential components are used for the electromagnetic fields on the surface of the elements as an unknown parameter. As concrete examples, they are applied to a cubic resonator and a rectangular resonator which contained a dielectric material. It was confirmed that except for a few zero eigenvalues, all nonzero eigenvalues corresponded to resonant modes. Specifically, if new rectangular parallelepiped elements are used, it is shown that no generation of spurious solutions occurs with nonzero eigenvalues.
Recording material characteristics needed for realization of phase‐change type optical disk
Authors: Funakoshi Nobuhiro 
Published: July 2007

AbstractTo apply phase‐change type material to an optical disk, thermal analysis of the material was carried out at a traveling speed of 25 m/s, realizing that the erasing process is based on crystallization of an amorphous material. As a result, the conditions for a circular beam needed to realize phase‐change type recording materials and the relationship between the crystallization energy and frequency factor were clarified. It was found also that if the transformation mode is higher than 3, optical disks compatible with the presently commercialized disks can be fabricated.