bluuebunny/crossref_metadata_2025_split huggingface dataset:
Precise measurement of resonance current and frequency characteristics of quartz oscillators for oven‐controlled crystal oscillators
Authors: Koyama Mitsuaki , Watanabe Yasuaki , Sekimoto Hitoshi , Oomura Yoshimasa 
Published: July 2007

AbstractThis paper presents a precise measurement method for obtaining the drive power dependency of frequency in highly stabilized quartz‐crystal oscillators. The method is aimed at improving the frequency stability of crystal oscillators and, in particular, oven‐controlled crystal oscillators (OCXOs). It uses a transistor Colpitts oscillation circuit which features excellent resolution and reproducibility of electrical current measurements as well as higher operating frequencies than those of conventional techniques such as transmission or reflection methods. In this paper, the authors demonstrated concepts of this method and a corresponding measurement system. The proposed method also was applied to SC‐cut crystal oscillators used in OCXOs which had shown nonsatisfactory frequency stability (discussed earlier by the authors). Here, the authors demonstrated that those problems were caused by frequency jumps in the oscillator frequency‐versus‐current characteristic. It was shown also that OCXO circuits with excellent reproducibility of temperature characteristics can be implemented by using an appropriate level of driving current to drive the quartz oscillator in the generation mode.
MgO powders for protective layer of alternating current plasma display panel
Authors: Koiwa Ichiro , Kanehara Takao , Mita Juro , Ono Sachiko , Osaka Tetsuya 
Published: July 2007

AbstractThe MgO powder used for a screen‐printed protective layer on plasma display panels was evaluated. The MgO powder was formed by either vapor‐phase oxidation or decomposition of Mg(OH)2. For the same BET value, the diameter of MgO particles formed by the latter method was larger than that by the former method. It was found that the particle diameter calculated by Scherrer's equation using the half‐value width of an X‐ray diffraction pattern was less than one‐fifth of that calculated using the BET value. When the distribution of the particle size was evaluated by the centrifuge precipitation method, it was found that both the median and modal diameters of the MgO powders formed by the latter method were larger than that by the former method. The powder formed by the latter method also contained powder with diameters of less than 20 nm; the weight ratio of the fine powder to the entire MgO powder was 5.5 ∼15.9 wt%. The transmission electron microscopy (TEM) observation revealed that the powder formed by the former method had a higher crystallinity and that the powder formed by the latter method tended to aggregate. When protective MgO layers were fabricated by sintering MgO powder formed by the above two methods, the powders oriented in the (111) orientation and the MgO formed by the former method had a higher crystallinity. It was concluded that, since the MgO powder formed by the former method (vapor phase method) had a finer particle diameter, higher crystallinity, and higher uniformity than the powder formed by the latter method (decomposition of Mg(OH)2), the MgO powder formed by the former method is more suitable for the alternating current plasma display panel (AC‐PDP) printed protective layer.
Soliton system evaluations using fibers with dispersion and loss fluctuations
Authors: Ishiba Kazuo , Komatsu Tadayoshi , Takahara Mikio 
Published: July 2007

AbstractIn the development of practical multimedia systems, greater capacity is desired in a long‐distance large‐capacity transmission system. A number of studies have been undertaken to develop a long‐distance large‐capacity system. Several long‐distance transmission experiments for high‐density transmission by wavelength demultiplexing method (WDM) have been reported recently. However, more of the experimental examples have reported on soliton transmission than on WDM systems. Hence, the former is considered more advanced. It is necessary to prepare a fiber of a length of approximately 10, 000 km for ultralong‐distance transmission experiment. Since this is difficult to obtain, repetitive experiments are often the case. However, such an experiment does not disclose the effects of dispersion and loss fluctuation in the fiber. In this paper, the effect of fluctuation in dispersion and loss in the fiber is studied by simulation so that the resilience of the soliton to the variations of the fiber characteristics is evaluated.
Analysis of steady‐state characteristics in a push‐pull current‐fed high‐power factor converter using a two‐input‐winding transformer technique
Authors: Takeuchi Akira , Ohtsu Satoshi , Muroyama Seiichi 
Published: July 2007

AbstractA two‐input winding transformer technique for high‐power factor converters has been developed. This technique results in reduced size and enhanced conversion efficiency. Input‐current wave‐shaping and fast output‐voltage regulation are achieved by controlling charge and discharge of an energy‐storage capacitor on the primary side of the transformer to compensate for the difference between the ac input and the dc output power. Thus, most of the input power is supplied to the output through only a single conversion stage and the low‐frequency ripple in the output voltage can be reduced with a small output capacitor. In addition, operation in the continuous conduction mode makes it possible to reduce the size of the input filter, concomitantly decreasing conduction loss.This paper discusses a push‐pull current‐fed converter that uses this technique. In this circuit, it is necessary to restrict the pulsewidth for the input current control because the pulsewidth for the output voltage control should be expanded to decrease the rms value of the current flowing in the switches. The characteristics of input current distortion caused by this restriction are analyzed and optimization, which takes into account harmonic current characteristics and reduction of conduction loss, is clarified. High‐power factor and an efficiency of 88 percent were achieved experimentally.
Traveling‐wave microwave power combiner
Authors: Nogi Shigeji , Shimura Tatsuhiro , Fukui Kiyoshi 
Published: July 2007

AbstractThis paper discusses the design and characteristics of power combining and power dividing‐combining by means of traveling‐wave power divider/combiners using waveguides. First, the perfect power combining condition is given when the divider/combiner is used as a single power combiner. From the numerical analysis based on the equivalent circuit, it is shown that a highly efficient power combining is possible over a very broad frequency range. It is shown also that the degradation of the combining efficiency with respect to the deviation of the input amplitudes and phases from the designed values is small.For a power dividing‐combining system using two identical power divider/combiners, it is shown that a broadband characteristic can be obtained, the bandwidth increases with a number of branches, and the performance degradation by failure of one of the devices in the unit amplifiers can be kept minimum by appropriate choices of the device location. Further, the four‐ and six‐way power dividing‐combining experiment has been carried out at X‐band. The validity of the theory was confirmed. In the six‐way power dividing‐combining, a broadband characteristic was realized as evidenced by the bandwidth of 2.87 GHz with a combining efficiency of more than −0.5 dB and of 3.90 GHz with a return loss of less than −20 dB.
Analysis of operating mechanism in semiconductor optical modulator with electron‐depleting absorption control
Authors: Kuwamura Yuji , Yamada Minoru , Hashimoto Susumu 
Published: July 2007

AbstractThe optical absorption mechanism of a semiconductor optical modulator with electron‐depletion absorption control was theoretically and experimentally investigated. In the doped direct transition semiconductor material, optical absorption increased when electrons were depleted. In the region where electrons are depleted, the number of electrons in the conduction band and holes in the valence band decrease, the impurity energy level shifts due to the decrease of the screening effect and the internal electric field strength increases. Because of these phenomena, the band‐to‐band electron transition probability increases. As a result, the optical absorption increases in the modulator.
Dependence of plasma parameters on electric potential of electrode in microwave plasma
Authors: Kato Isamu , Matsushita Toru , Yamashita Makoto 
Published: July 2007

AbstractThe authors have been studying the double‐tubed coaxial line‐type microwave plasma chemical vapor deposition (MPCVD). The discharge tube of the present MPCVD is a dual‐tube structure made of a fused quartz outer discharge tube and stainless steel inner tube. The authors have discovered that the ion bombardment energy can be controlled without varying the electron densities and temperature by changing the potential of the substrate placed in a spatial after‐glow plasma. In the present research, it is found that the ion bombardment energy can also be controlled by changing the potential of the inner tube placed in the discharge plasma. However, the electron densities and temperature have exhibited a tendency different from the one when the substrate potential is varied. Hence, a theoretical calculation has been carried out on the electron densities and temperature based on Maxwell‐Boltzmann distribution. It is found that a different tendency can be explained from the fact that the electrons successively vanish on the deposition chamber wall from the higher‐energy side as the plasma spatial potential is reduced from about 13 V to 4 V so that the electron velocity distribution is modified.
Analysis method for light scattering from magnetic materials by the three‐dimensional boundary element method
Authors: Ogawa Masatsugu , Nakada Masafumi , Okada Mitsuya , Itoh Masaki 
Published: July 2007

AbstractTo analyze the light scattered from a magneto‐optical disk, a method is proposed for calculating the light scattered from a magnetic material with grooves. The model used is divided by an infinite boundary between the free space or an isotropic dielectric and an isotropic magnetic material. By using the relative permittivity of the isotropic magnetic materiel, the governing equation for the magnetic material is derived from Maxwell's equations. The three‐dimensional boundary element method is applied to this equation. The boundary element equation for free space or an isotropic dielectric material is the one in which the boundary element method is applied to a general Helmholtz equation. The one in the magnetic material is obtained by adding the volume integral in the magnetic material to the general equation. If boundary elements are large, the integral in the magnetic material near the boundary is evaluated at too small a value. The numerical results oscillate with only the foregoing method. To resolve this problem with taking practical memory size and computation time into consideration, an attenuating term is added to Green's function used in the integration in the magnetic material. With the method proposed, the optical scattering from a magnetic material can now be analyzed.
Barrier layerless submicron aluminum‐damascene interconnection using aluminum chemical vapor deposition with a new nucleation method
Authors: Shinzawa Tsutomu , Sugai Kazumi , Hayashi Yoshihiro , Nakajima Tsutomu , Kishida Shunji , Okabayashi Hidekazu , Tsunenari Kinji , Murao Yukinobu , Kobayashi Akiko , Yako Tadaaki 
Published: July 2007

AbstractBarrier layerless submicron damascene interconnection has been realized by using a combination of novel aluminum chemical vapor deposition (AI‐CVD) and chemical mechanical polishing (CMP) techniques. A new nucleation method with tetrakis‐dimethyl‐amino titanium (TDMAT) gas pretreatment has enabled AI‐CVD to fill trenches without using a barrier layer which causes high resistivity. As a result, this technology achieved Al damascene interconnections with resistance as low as 600 ω/cm with half‐micron wide line and an aspect ratio of 3. This line resistance is one‐third of that for a conventional reactive ion‐etched Al line with an aspect ratio of 1.
Compensation for waveform distortion in a transmission fiber with loss by optical phase conjugation
Authors: Watanabe Shigeki , Shirasaki Masataka , Chikama Terumi 
Published: July 2007

AbstractA new method is proposed to compensate for chromatic dispersion and self‐phase modulation in a transmission fiber with a loss using optical phase conjugate (OPC). The ratio of the optical Kerr effect and the dispersion was designed to be equal at each position before and after the OPC. The pulse shape is precompensated before OPC by transmission through a fiber with large dispersion whereas the transmission line consists of an optical amplifier repeated fiber link with a small dispersion. A computer simulation demonstrates effective compensation for waveform distortion in a 40‐Gb/s no‐return‐to‐zero (NRZ) intensity‐modulated light transmission. The method will be effectively applied to both wavelength demultiplexing method (WDM) systems and long‐haul transmission systems.
Scattering parameter estimation accuracy of root‐MUSIC algorithms in electromagnetic wave scattering measurements
Authors: Yamada Hiroyoshi , Yamamoto Kazuaki , Yamaguchi Yoshio , Sengoku Masakazu 
Published: July 2007

AbstractAn application of the superresolution method for the analysis of the electromagnetic scattering data is expected to be effective for experimental verification of the geometrical optics approximation theory and the analysis of multiple paths. There exist many techniques for the superresolution method. It is desirable to select an appropriate technique based upon the characteristics of the individual algorithms. Among these techniques, the Root‐MUSIC method has been proposed; this method enables treatment of the signal attenuating exponentially with respect to frequency. In the modified Root‐MUSIC method, arbitrary frequency characteristics can be treated.This paper investigates the estimation accuracy of the scattering center and the attenuation coefficient when the Root‐MUSIC method and the modified Root‐MUSIC method are applied to the estimation of scattering. With the backscattering data of a conducting sphere, the estimation accuracy of the scattering parameters versus the signal‐to‐noise ratio (SNR) and the number of snapshots is investigated by computer simulation. As a result, it is found that the estimation accuracy of the modified Root‐MUSIC method is much better than that of the conventional Root‐MUSIC method in the case of a low SNR and a small number of snapshots. Experimental results are also reported.
Various equivalent circuits for thickness mode piezoelectric transducers
Authors: Chubachi Noriyoshi , Kamata Hiroshi 
Published: July 2007

AbstractThe equivalent transmission line model originally proposed by Nukiyama [5] and applied to the thickness mode piezoelectric transducers by Kikuchi et al. [6] is reviewed and its characteristics are described. The model is compared with those proposed by Mason [4] and by Krimholz et al. [2]. The equivalent transmission line model developed by Kikuchi et al. [6] was derived from the fundamental piezoelectric equation and Newton's equation of motion via the Laplace transformation. A new equivalent circuit in a time domain was derived as well. By comparing the equivalent circuit in a time domain with the equivalent transmission line model [6], it was demonstrated that the equivalent transmission line model is a fundamental equivalent circuit that is effective both for analyses in a time domain and for conventional analyses in a frequency domain. It is also demonstrated that, when the simultaneity between electric and acoustic signals is neglected, the equivalent circuits [2, 4] can be derived from the equivalent transmission line model.
Properties of phase‐conjugate reflectivity of self‐pumped four‐wave mixing
Authors: Dohata Masayoshi , Okamoto Atsushi , Enbutsu Koji , Sato Kunihiro 
Published: July 2007

AbstractThe properties of the phase‐conjugate reflectivity are analyzed anew for the self‐pumped four‐wave mixing in which only the two waves, i.e., the forward pump wave and the probe wave, are incident on the photo‐refractive crystal and the phase‐conjugate wave of the forward pump wave is used as the backward pump wave.First, by means of a model in which a Cat‐type phase conjugator is placed outside the interaction region, the equation for the phase‐conjugate reflectivity of self‐pumped four‐wave mixing using a transmission grating is derived. Next, the numerical calculations have been used for the first time to determine the effects of the coupling strength, the probe ratio as the incident intensity ratio of the forward pump wave to the probe wave, and the reflectivity of the Cat‐type phase conjugator on the entire phase conjugate reflectivity. Since the equation describing the phase‐conjugate reflectivity has multiple solutions, the strict analysis of the equation shows that the phase‐conjugate reflectivity has multiple values. Further, the conditions for high phase‐conjugate reflectivity has been studied.
A finite‐element beam‐propagation method for strongly guiding optical waveguides with magnetooptic materials
Authors: Tsuji Yasuhide , Koshiba Masanori , Tanabe Tomohide 
Published: July 2007

AbstractTo the best of the knowledge of the authors, the formulation is carried out for the first time on the finite‐element beam‐propagation method for the analysis of the magnetooptic waveguide in which the structure varies along the propagation direction. The present method is applicable not only to the case in which refractive index difference is small but also to the case for the TE mode and the TM mode propagating in a waveguide with a large refractive index difference. To suppress the spurious reflection from the computational window edges, the transparent boundary condition is applied.
Piezoelectric vibratory gyroscope as an angular velocity sensor
Authors: Konno Masashi , Sugawara Sumio , Kudo Subaru 
Published: July 2007

AbstractGuidelines are given for designing a piezoelectric vibratory gyroscope to be used as an angular velocity sensor. First, a basic equivalent circuit is given and an approximate equation is derived for sensitivity. Based on the equation, guidelines and issues related to improving sensitivity are discussed. The relationship between the output signal and difference in resonance frequencies of the driving and detecting sides is investigated for cases where the angular velocity is either constant or changing sinusoidally with time. The results are then used to determine the resonance frequencies. Furthermore, a design guideline based on an integral equivalent circuit, which has taken the effects of leakage output into consideration, is discussed and an approach is suggested for supporting the gyroscope. Finally, the performances of various gyroscopes are compared and the utility of a piezoelectric gyroscope as an angular velocity sensor is discussed.
Properties of zinc oxide films deposited by a radio‐frequency magnetron mode electron cyclotron resonance sputtering system
Authors: Kadota Michio , Minakata Makoto 
Published: July 2007

AbstractWe reported that zinc oxide (ZnO) films deposited by direct current (DC)‐mode electrocyclotron resonance (ECR) and radio frequency (RF)‐mode ECR sputtering systems had shown excellent piezoelectric properties and c‐axis orientations. The RF‐mode ECR sputtering system was capable of depositing ZnO films on glass substrates without evidence of column and fiber grains in cross‐section analysis while driving a 1.1‐GHz fundamental Rayleigh surface acoustic wave (SAW). In this paper, we investigate the properties of ZnO film deposited by an RF‐magnetron‐mode ECR sputtering system which has added magnets to the outside of a cylindrical zinc metal (Zn) target of the RF‐mode ECR sputtering system. The ZnO film on the glass substrate deposited by this system was capable of driving a 1.3‐GHz fundamental Rayleigh SAW. This shows a higher frequency than the previously reported ZnO film. This film exhibits most of the same effective electromechanical coupling factors (keff) as the theoretical keff values calculated by finite‐element method (FEM) using the constants of ZnO single crystal (that is, 97 percent of theoretical value) and 0.6 ∼ 3.6 dB lower insertion loss in comparison with the films deposited by the DC‐mode ECR and the RF‐mode ECR. A (1120) plane epitaxial ZnO film was deposited at low temperatures on an R‐plane sapphire substrate using this system and was capable of driving a 2.54‐GHz Sezawa wave. By measuring the photoluminescence property of a thin, 1.2‐μm, epitaxial ZnO film, free exitons are observed for the first time.
Use of multiple‐valued logic with 1.9‐V operational power supply to obtain a high‐speed current‐mode logic circuit
Authors: Sugimoto Yasuhiro 
Published: July 2007

AbstractThis paper proposes a new construction of bipolar current‐mode (CML) logic circuits based on the multiple‐valued logic concept. Applying the multiple‐valued logic concept, the new logic function, which can replace the conventional stack logic circuit and can be operated by a low supply voltage, can be realized. In conventional circuits, it is difficult to generate a signal with multiple voltage levels at the same time as the output of a logic gate and logic gates must be connected by placing a level‐shifter between them.A circuit is devised in this study that generates the multiple‐valued logic levels (three levels in this paper) simultaneously at the output of the logic gate. Also, it is examined whether or not the basic logic functions, such as NAND, NOR, EX‐OR, and D‐Latch, can be realized by the proposed configuration. The characteristics of the proposed circuit are circuit simulated by a SPICE circuit simulator. It is seen as a result that the power consumption, the logic density, and the high‐speed performances, comparable to the conventional stacked‐gate logic circuit, can be realized with the low supply voltage of 1.9 V.
Operation of optical information retrieval system using spatial light modulator
Authors: Hatori Masaaki , Shioya Kouhei , Ohkawa Masashi , Sekine Seishi , Tsuchida Keiichi , Mita Motohito 
Published: July 2007

AbstractOptical information retrieval systems based on Fourier optics and using holographic memories of high‐density recording capability, which raise the possibility of parallel information processing, have been proposed for a long time. However, the development of spatial light modulators which are the key devices in such systems has been delayed considerably and, so far, there is no report on optical information retrieval systems using spatial light modulators.With this as background, a spatial light modulator (SLM) based on a large‐permittivity crystal is fabricated and its operation in a small‐size system is verified. First, based on the function of the spatial modulator, the hologram and the detection sections are designed and specifications of the system are decided. Next, the two different schemes of synchronous and direct detection methods are applied to the information retrieval of 18 bits consisting of nine pieces of holograms. As a result, it is understood that retrieval is possible using even the currently available spatial light modulators. The relation between the functions of the SLM and the system also is clarified. However, there are several problems in realization of such systems, a discussion of which is presented in this paper.