bluuebunny/crossref_metadata_2025_split huggingface dataset:
A quantitative evaluation method for the biological effects |of ion‐current
Authors: Yamashita Masaji , Shimizu Koichi , Shimizu Hideo , Matsumoto Goro 
Published: July 2007

AbstractAn experimental apparatus called an ion‐current shuttlebox, was developed to evaluate quantitatively the biological effects of ion‐current in air. It consists of an ion‐generating long narrow cage for a rat and an automatic data acquisition system. The cage is divided into two parts, i.e., an ion‐exposing area and a control area. Ion‐current is generated by corona discharge of thin wires located above the cage. Two pairs of grids control the amount of ion‐current in the exposing area and eliminate ion‐current in the control area. In a computer simulation, the loci of ion‐particles were obtained which provide the appropriate conditions of potentials for the two grids. In basic experiments it was confirmed that ion‐current distribution is uniform in each area and is symmetrical between the two areas. The apparatus can expose ion‐current of between 0 to 1 μA/m2 (continuously controllable) to a rat. A technique was devised which depresses the ozone generation by heating the corona wires. The behavior of a rat is recorded and analyzed in an automatic position sensing system controlled by a microcomputer. In sham exposing experiments, it was confirmed that this apparatus does not affect the circadian rhythm of the rat and there is no preference by the rat for either of the two areas.
A quasi‐millimeter wave gaas high‐power fet
Authors: Mitsui Yasuo 
Published: July 2007

AbstractA monolithic quasi‐millimeter wave power combiner type GaAs high‐power FET is proposed which combines source island viahole PHS structure FET cell and power combiner and divider circuits on the same substrate. Since the individual island source electrode is connected directly to the heat sink electrode via holes through an extremely thin GaAs substrate, the parasitic source inductance per unit gate width has been reduced to 1.0 pH/mm, and the thermal resistance of the device has been reduced by 40 percent compared to conventional structures. Also, the power added efficiency of more than 80 percent has been achieved by the four‐cell combiner of FET cells with gate width 800μm. This shows that this monolithic structure is effective in suppressing the gain reduction due to the phase differences between the parallel gate figures at high frequency. At 28 GHz, the fabricated FET achieves 1 dB compression point power of 1.1 W, linear power gain of 4.0 dB, the power · (frequency)2product of 860 W · GHz2. Also, such reliability tests as temperature cycling, operation test, and high‐temperature ambient have been carried out, and it has been confirmed that the test device has the basic reliability level suitable for practical quasi‐millimeter wave communication systems.
Analysis of polarization‐maintaining optical fibers with circular pits outside a circular core
Authors: Hinata Takashi , Yoshikawa Hiroshi , Kuroiwa Hitoshi , Hosono Toshio 
Published: July 2007

AbstractThis paper investigates the polarization‐maintaining optical fibers with one circular hollow pit (SCF) and two circular hollow pits (DCF) outside a circular core. The modal birefringence of the following fibers are investigated:
with homogeneous core,
with radially inhomogeneous core.
The relation between the modal birefringence (ΔB) and the polarization dispersion (Δτ) is also investigated. The homogeneous core fibers are analyzed by the improved point‐matching method. To analyze the inhomogeneous core fibers, the core is divided into several homogeneous layers and the improved point‐matching method is then applied. The main conclusions drawn in this paper are as follows: (1) the maximum modal birefringence for DCF can be attained 3.5 times larger than that for SCF; (2) the modal birefringence for inhomogeneous core fiber cannot be greater than that for homogeneous core fiber, even if the core index is chosen equal to the maximum index value of inhomogeneous core; (3) zero polarization mode dispersion can be attained near the wavelength where the modal birefringence takes the maximum value; however, it is not zero at that very wavelength. The relative error of propagation constant computed by our method is less than 10−9 so that the relative errors of the modal birefringence and polarization mode dispersion are less than 10−4.
Considerations of distributed capacitance of high‐voltage transformers
Authors: Ohtsu Satoshi , Ogata Tsutomu 
Published: July 2007

AbstractAn effective means to achieve a small and light‐weight high‐voltage power supply is to raise the conversion frequency of the supply. At present, however, the conversion frequency is largely limited by the distributed capacitance of high‐voltage transformers and the switching time of semiconductor devices. Reduction of the distributed capacitance of a high‐voltage transformer and a new method of analysis which can quantitatively describe the relation between transformer structure and distributed capacitance were achieved. Using the proposed method of analysis, the distributed capacitance is calculated using the winding scheme, core dimension, number of bobbin splits, class and material for winding insulation, core size and impregnation material as the parameters. The calculated values are compared with the measured values and the effects of the parameters on the distributed capacitance are discussed. By using a four‐split bobbin, the distributed capacitance is reduced by 10 percent less than the nonsplit bobbin. The capacitance using the core with a circular center pole is reduced by approximately 10 percent compared with the square center pole. Using class 1 insulation winding, the capacitance is reduced by 10 percent compared with class 2 winding insulation material.
High‐speed switching of the power transistor in a DC‐DC converter with current feedback and core saturation
Authors: Harada Koosuke , Sakamoto Hiroshi , Shoyama Masahito 
Published: July 2007

AbstractTo reduce the size and weight of a switching dc‐dc converter, it is effective to increase its switching frequency. This requires the reduction of the switching time and switching loss. This paper introduces a dc‐dc converter with a short turn‐off time and a high efficiency at a switching frequency up to the order of megahertz. This is achieved by using a bipolar transistor with current feedback and core saturation. The turn‐off mechanism was analyzed by using an equivalent circuit. The turn‐off time was found to be considerably shortened by the quick discharge of the excess carrier in the base region. This is due to the formation of an LC circuit consisting of the saturated inductance of the current feedback transformer which magnetically saturates during the turn‐off period, and the base‐emitter capacitance of the switching transistor. This phenomenon can be used widely for high‐speed and high current switchings.
Os‐doped γ‐Fe2O3 thin‐film media for perpendicular recording
Authors: Ohtani Yoshimitsu , Ohta Satoshi , Terada Akira 
Published: July 2007

AbstractSince Os‐doped γ‐Fe2O3 sputtered thin film can be added in perpendicular anisotropy by annealing in the magnetic field perpendicular to the film surface, it has potential as a perpendicular magnetic recording media. Herein we examine both a method to dope Os by reactive sputtering and the causes contributing to the induced magnetic anisotropy. Its performance as a perpendicular magnetic disk has yielded the following results. When Os is solidified during the formation of Fe3O4 film by reactive sputtering, reproducible doping is possible. When γ‐Fe2O3 is formed in atmospheric oxidation, the coercive force increases in proportion to the Os doping (Hc ∝ 500x, x = Os at. %). Magnetic anneal is effective for the γ‐Fe2O3 state, and a large anisotropy can be added when the oxygen partial pressure in the atmosphere is increased. Furthermore, the activation energy for the induced anisotropy was approximately 1.0 eV. The induced anisotropy seems to be related to the vacancies. In the recording reproduction using a thin‐film ring head, the reproduced isolated waveform is dipulse, thereby confirming the recording with a large perpendicular component (dipulse ratio 0.7).
Theoretical investigation for coupling between a laser diode and an optical waveguide via a gap
Authors: Fujii Yukio , Matsuhara Masanori , Kumagai Nobuaki 
Published: July 2007

AbstractTo develop a high‐grade optical communication system, numerous studies have been performed on the single longitudinal mode operation of a laser diode (LD). The optical feedback generated at the coupling junction of the LD and the optical waveguide is a serious problem since it is a cause of the deterioration of the stability of the operation of the single mode laser. This paper describes a theoretical study of the reflected and transmitted light at the open end of the LD and at the junction between the LD and the optical waveguide via a gap by means of the boundary element method and the eigenmode expansion method. It is confirmed from the viewpoint of electromagnetic theory that among various configurations for elimination of the feedback, the one with a double‐layered antireflection coating is the most effective. The analysis method used in this paper, unlike many other methods, has no restriction on the difference in the refractive index between the core and cladding. It can be extended easily to the case where the gap region consists of multimedia.
A mode‐filter type light intensity modulator using zincblende crystals
Authors: Ohke Shigeaki , Cho Yoshio 
Published: July 2007

AbstractThis paper investigates optical‐wave propagation characteristics in a light intensity modulator using zincblende crystals. Special attention is given to the transformation of the quadratic surface equations (the refractive‐index ellipsoid equations) and the quadratic curve equations (the polarization plane equations) into their standard forms. Assuming that the light wave enters from a cleavage plane {110}, the behavior of the main refractive index axis in the direction of an electric field which is perpendicular to an arbitrary plane {aac} was investigated. The results show that there are two main refractive‐index axes in the incidental light‐wave plane in the new coordinate system. The results were applied to the examination of the characteristic of the crystal‐axis direction dependence of the retardation modulator, a device using the electrooptical effect. Highest efficiency can be obtained by using the crystal plane {110} for the TE polarized light‐wve incident. The modulating factor can be controlled by the length of the device alone, except for {100} and {111} in which the direction of the polarized light agrees with the direction of the principal refractive‐index axis.
Characteristics of compressed magnetic field (CMF) magnetron sputtering technique using magnetic target
Authors: Hata Tomonobu , Ohtsubo Katsuaki , Hada Toshio , Takahashi Takakazu 
Published: July 2007

AbstractThis paper reports on the experiment of the high‐rate sputtering of Co‐Cr film by the compressed magnetic field magnetron sputtering technique. When a magnetic target is used in the magnetron sputtering technique, utilization efficiency of the target is as low as 20 percent and the deposition rate is low. To cope with this problem, Co‐Cr film is fabricated by the method which has been proposed and successfully used for the dielectric target. The characteristics of the fabrication system and the constructed film were evaluated. It is seen that the area utilization of the target is as high as 90 percent. The film deposition rate is 0.15 μm/min for the target‐substrate distance of 30 mm, gas pressure 0.3 Pa, and input power 4.6 W/cm2. The deposition rate is 0.08 μm/ min for the target‐substrate distance of 50 mm, for which a uniform deposition is obtained. These figures are sufficiently high. It is also seen that when the third component (Fe) is to be included in the film, the content can be adjusted over the wide range of 3 to 12 percent by varying the magnetic field of the solenoid coil.
Vectorial wave analysis of stress‐applied polarization‐maintaining optical fibers
Authors: Hayata Kazuya , Koshiba Masanori , Suzuki Michio 
Published: July 2007

AbstractThe modal analysis of stress‐applied polarization‐maintaining optical fibers is very difficult due to their complex refractive‐index distribution and their large anisotropy caused by a thermal stress. Therefore, only a few approximate analyses have been tried so far. In this paper, to estimate accurately the transmission characteristics of these stress‐applied polarization‐maintaining optical fibers, we present a vectorial wave analysis using a vector H‐field finite‐element method. First, to verify the accuracy of solutions, numerical results for a step‐index circular‐core fiber are presented and the relation between the number of elements and the accuracy of calculation is also clarified. Next, the stress analysis and the vectorial wave analysis of stress‐applied polarization‐maintaining optical fibers with an inner cladding are carried out and the difference of transmission characteristics between the fibers having a different parameter is discussed. Further, we propose an approximate method for calculating the splice loss between two optical fibers and show the normalized radiated power caused by transverse offset, longitudinal separation, and angular misalignment between two stress‐applied polarization‐maintaining optical fibers.
Fabrication of NbN josephson junction integrated circuits using Si insulation layer
Authors: Hirano Mikio , Mori Hiroyuki , Tarutani Yoshinobu , Yano Shinichiroo 
Published: July 2007

AbstractIn the fabrication of Josephson junction integrated circuit, it is most important to align the superconducting critical current ImO of the junction. This paper reports a fabrication of interlayer insulating film with a view to reducing the fluctuation of ImO of NbN‐Oxide‐PbInAu junction of 1.5 μm. The main cause of the fluctuation of ImO is the variation of the junction area due to remnant of interlayer SiO insulating film generated in the aperture of the junction. To solve this problem, several interlayer insulators other than SiO have been investigated. It is found that Si is appropriate for forming the junction aperture without remnant. The Si film fabricated by evaporation has been a film close to amorphous. The pinhole defect density is 10/cm2 (film thickness 300 nm), which is smaller by two orders of magnitude than the one in SiO films. When Si films are used for interlayer insulation of NbN Josephson junction devices, the maximum distribution width of ImO is ±12% (σ ± 8%), which is about 1/2 for the case of SiO films. Usefulness of the film has been confirmed in application to the interlayer insulation film of the logic array with 750 gates. The measured delay time of a chain circuit made for trial is 14 ps/gate in a 2 input OR gate.
Preparation and properties of grain‐orientation Bi4Ti3O12 ceramics by cold‐uniaxial pressing method
Authors: Shoji Kazuo , Uehara Yasuo 
Published: July 2007

AbstractWhen Bi4Ti3O12 is viewed as a piezoelectric material, since the direction of the spontaneous polarization is limited in two dimensions, it is necessary to perform grain orientation. In this paper, as a method for the grain orientation at room temperature, a cold‐uniaxial pressing method is considered, and the fabrication method of Bi4Ti3O12 grain‐orientation ceramic is examined. Furthermore, the electrical characteristics of the obtained grain‐orientation sample are also examined. This method performs grain orientation by utilizing the shape anisotropy of the ceramic powder. Therefore, first, the relation between the firing process and the grain growth is examined for normal firing sample. Next, the orientation sample is obtained by applying a uniaxial pressing and a main firing to the obtained plate‐like primary particles. As a result, it has been found that the orientation by this cold‐uniaxial pressing method is due both to the orientation of primary particles during the deformation by uniaxial pressing, and also to the grain growth during the main firing. It has also been found that oriented samples comparable to the hot‐working method can be obtained by this method in terms of grain orientation and electrical characteristics.
Solid thin‐film energy‐transfer dye lasers
Authors: Muto Shinzo , Shiba Fumikazu , Iijima Yoshitsugu , Hattori Kiminori , Ito Chiaki 
Published: July 2007

AbstractSolid thin‐film energy‐transfer dye lasers (thin‐film ETDL) were developed by doping donor‐acceptance dye pairs in the polymer waveguide. Many types of thin‐film ETDL having a slight degradation of the pumping light were obtained. As a result, the wavelength range of the ETDLs became very wide covering almost the entire region from near UV to near IR. The thin‐film cascade ETDL operation was materialized on the first attempt. The spectral narrowing and the tuning of the solid‐film ETDLs are easily obtained by using the DFB operation. The results show the possibility of making a practical compact laser source with a variable wavelength.
Preparation and characteristics of Co‐Cr films with perpendicular magnetization by CMF‐magnetron sputtering
Authors: Hata Tomonobu , Ohtsubo Katsuaki , Kita Yutaka , Hada Toshio , Takahashi Takakazu 
Published: July 2007

AbstractIt is known that the high‐rate deposition of magnetic thin‐films by using the magnetron sputtering method is very difficult since the target shields the magnetic field. We carried out the high‐rate deposition of Co‐Cr films by using the compressed magnetic‐field (CMF) magnetron sputtering method in which the magnetic pole does not touch the target. This paper describes the features of the apparatus, and the investigation of the orientation of the c axis and the difference in the magnetic characteristics, from the changes of the gas pressure of Ar, the temperature of the substrate, and the deposition rate of the film. The results show: (1) the deposition rate of the film was 0.26 μm/min maximum showing the possibility of a high‐rate deposition of the films; (2) the lower the gas pressure, and the higher the film deposition rate, the better the film characteristics; (3) the temperature of the substrate has a slight effect on the orientation, so that the films can be prepared at a temperature as low as 100°C; and (4) the smaller the half width of the rocking curve, the greater the coercive force. Finally, the CMF‐magnetron sputtering method is very effective in preparing perpendicular‐magnetization Co‐Cr films at a low temperature and a high preparation speed.
ESCA compositional profiles and electrical properties of diamond‐like carbon film/Si MIS structure
Authors: Mizokawa Yusuke , Komoda Osamu , Miyasato Tatsuro , Hasegawa Shigehiko , Tokumura Masao , Nakamura Shogo 
Published: July 2007

AbstractDiamond‐like carbon (DLC) films were deposited on silicon wafers by hydrogen gas reactive dc‐sputtering of graphite and fabricated MIS diodes. ESCA chemical depth profiles showed that almost no impurities such as oxygen and nitrogen were present in the bulk of DLC films. In the interfacial region between DLC and Si substrate, a small amount of Si‐C bonding as well as natural oxide of silicon were detected. It is found that the 1st‐derivative spectrum of C‐KLL Auger line in ESCA from the DLC film surface was very similar to the C‐KLL AES spectrum from natural diamond. This suggests that DLC film has a fairly diamond‐like tetrahedral sp3 C‐C bonding configuration. The C‐V curves of the Hg/DLC/Si MIS diodes showed accumulation, depletion and inversion characteristics. The charge trapped in DLC film and the interface state density distribution as a function of the surface potential were obtained first. Both the amount of trapped charge and the C‐V hysteresis were considerably smaller compared to an Si3N4/Si diode.The interface state density curve exhibits a “U” shape and the minimum density was less than 3 × 1010/cm2/eV in the vicinity of the mid‐band gap.
High‐precision coaxial cable attenuation measurement using resonant method
Authors: Aida Kazuo 
Published: July 2007

AbstractThis paper discusses a highly precise method of measurement for the attenuation of a coaxial cable using a short test‐piece. The proposed method is used to compose an open‐ended resonator by the coaxial cable and to determine the attenuation from the resonant characteristics. To realize a highly accurate measurement using a very short test‐piece, the end effect of the cable must be corrected. A correction formula is presented, which by experiment, is verified as useful. The end effect in the proposed measurement is one order of magnitude less than that in the short‐circuit resonant method, which has been used in the past as the method measurement for the attenuation of the short test‐piece cable. It is shown that if the test‐piece is longer than a certain value, the measurement can be performed without considering the end effect. The measurement accuracy of 0.2 percent and the repeatability of 0.1 percent are realized by the proposed method. The upper limit of the cable attenuation that can be measured by the proposed method is discussed. When the resonant characteristics are measured by the half‐amplitude width, the upper limit is 7.6 dB, indicating that a wide range of attenuations can be measured. The proposed method is then applied to the measurement of the attenuation‐pressure characteristics of the submarine coaxial cable verifying the usefulness of the method.
Ferroresonant DC‐DC converter with high‐frequency drive
Authors: Karada Koosuke , Murata Katsuaki 
Published: July 2007

AbstractSince the switching loss in inverter circuits and the iron loss in ferroresonant circuits increase with frequency, the conversion efficiency decreases and the heat loss in the switching element and magnetic core increase at high frequencies. The requirement of radiating the heat has restricted the size reduction of power supplies. In view of the relation between the loss in the output transistor of an inverter and the switching frequency, it is found that the loss consists of the one independent of the switching frequency and the switching loss increasing in proportion to frequency. As the switching frequency increases, the latter becomes predominant. Hence, for a small and efficient converter at high switching frequencies, the switching loss has to be reduced. To this end, a relatively large capacitor is connected in parallel with the output transistor in this paper. As a result, sudden increase of the collector voltage at the shutdown of collector current is suppressed and the instantaneous collector loss is reduced. In the ferroresonant circuit for stabilization of output voltage, two saturable cores operating on a minor loop on the BH curve are used. Hence, the loss is small even at high frequencies and a superior constant voltage characteristic is realized by a feedback. The conversion efficiency is about 80% at the switching frequency of 500 kHz.