Chun-YeLI Toshio KAWASHIMA Yoshinao AOKI
In this paper, we introduce the concepts of multi-node and mono-node to expand the expansive graph grammar given by Shi and Fu to a larger family, the family that contains all rooted acyclic directed graphs. Shi and Fu's approach deals with rooted acyclic digraphs containing only mono-nodes. The ways of numbering and representing rooted acyclic directed graphs are modified and grammars for such graphs are given so that directed graphs containing even multi-nodes can be treated. Parsing algorithms are also given which are described with State-Space representation. Our algorithms are as efficient as those of Ref.(6). We have removed a constraint that the basis graph must be a tree from the expansive graph grammars of Ref.(6) without increasing the space or time complexity of numbering, rewriting and parsing.
Switched-Capacitor (SC) low-pass ladder filters based on the LDI transformation, have been successfully designed using the Lossless Discrete Integrators (LDIs) as their basic building blocks. However, the design of highpass ladder filters with the LDIs are not straightforward as the low-pass or bandpass case. On the other hand, a high-pass design is achieved easily by using a differentiator as the building block, instead of an integrator. Thus, a new design technique of Switched-Capacitor Modified Lossless Discrete Differentiators (MLDDs) is proposed in this paper. By using them as the basic building block, SC high-pass ladder filters are directly constructed based on the low-pass to high-pass transformation. Furthermore, a fully-differential architecture is applied to this MLDD design, and some MLDD alternatives are investigated for high-frequency and time-sharing applications.
Hideaki SONE Masao NAKAI Tasuku TAKAGI
The accumulated metallic phase arc duration in Ag electrical contacts was log-proportional to the amount of electrode mass change, and the relationship was irrespective of the air pressure condition. It can be considered that the electrode mass change closely depends on the metallic phase arc.
Masaaki DOI Noriko KURE Isamu KATO Koki SATO
Light intensity variation is performed in a multilayer optical circuit element consisting of stacked crossing thin film optical waveguides. The principle of operation is the interference of two guided light waves coupled with each other at the intersection of the waveguide of the optical circuit element. Measurements are carried out for each case of the coupling coefficient of the optical circuit element equal to 3 dB and not equal to 3 dB. The percentage variation obtained is 45%.
Minoru KAWANO Takeo KEUMI Isamu KATO Koki SATO
A multimode variable directional coupler has been fabricated by piling up films. It uses an electrostrictive element. The output powers can be continuously controlled over a wide range. The output powers from the two output ports of the coupler were equalized at a stress of 16.8 kg/cm2, and the loss due to the stress was small (0.19 dB).
Kazunari ISHIMARU Tetsuya TATSUMI Isamu KATO
We fabricated a-Si: H thin films outside the microwave discharge plasma and we varied the substrate bias to investigate the effect of ion bombardments of the film surface. Dark conductivity of the film decreases with increasing negative bias of the substrate with no dependence on the substrate temperature.
Hirokazu NAKAYAMA Wakao SASAKI Tatehisa OHTA
This letter reports the 10 ns (100 MHz) optoelectronic memory utilizing the mode-hopping phenomenon of a semiconductor laser. The hysteresis (wavelength bistability) features hold even at the speed of nanosecond. Some influences of VHF current modulation on mode-hopping are also measured.
Masahiro TOKI Yoshikazu TANAKA Hirotaka YAMAMOTO
A method is proposed to detect the surface wave propagation direction on the outer conductors of the transmission lines in cable systems, by means of a probe having a property of a directional coupler.
Takeshi KONDOH Osamu FUJIWARA Kazuo KATOH Takashi AZAKAMI
This letter presents a method for real-time visualization of static electricity distribution which can be achieved by rapidly measuring the voltages induced on the array electrodes. For verifying the validity of this method, the measurement examples on the charged sheets are demonstrated.
Takao NAGATOMO Keiichi KOHAMA Katsuhiko MIKAMI Osamu OMOTO
Gallium nitride single crystals were grown on (0001) oriented sapphire substrates by metalorganic vapor-phase epitaxy. The films on the initially nitrided sapphire surface showed an uneven surface with prominent hexagonal pyramids, while the films on the non-nitrided sapphire surface exhibited a relatively smooth surface although some fine pits were observed. All the films exhibited n-type conduction with carrier concentrations of 1017-1018 cm-3 and electron mobilities of 30-143 cm2/V sec.
Chun-Ye LI Toshio KAWASHIMA Tsuyoshi YAMAMOTO Yoshinao AOKI
Expansive graph grammar is one of the suitable tools for describing pattern structures in syntactic pattern recognition. To describe the numerical features of patterns and relations among them simultaniously with pattern structure, in this paper we show with expansive graph grammar: (1) how to describe the dependent relations among attributes of (sub) patterns with the concepts of inherited and synthesized attributes, (2) how to describe conditions supposed to be satisfied by attributes of patterns with the concept of predicate. An interpreter for such processing is presented based on the Problem-Reduction Representation (PRR). Some features of the method and the interpreter are discussed. It is showed that the method introduced in this paper is suitable for describing patterns in scene analysis when numerical features of patterns are considered.
Ben CHEN Mahoki ONODA Mineo KANEKO
With the development of LSI technologies, conventional circuit simulation using only single type of method has become unsatisfactory, i.e. circuit-level analysis based on device model spends much simulation time and relaxation methods have the problems on their accuracy. Therefore, it is necessary to develop the better methods to realize both high-speed and good accuracy. In this paper, a mixed-mode circuit-timing simulation method has been studied. It uses a new kind of automatic circuit partition approach--dynamic circuit partition process based on checking coupling factors between circuit nodes at every time point for better convergence. This method is based on examining the characteristic of circuit equations rather than circuit topology or function blocks. A mixed-mode simulation program--MMAPC for transient analysis of CMOS large-scale circuit has been developed and some simulation examples have been performed. The results show that MMAPC can be more than two orders of magnitude faster than a standard" circuit-level simulator (SPICE-like) while providing comparable waveform accuracy, and has better convergence property than general timing-level simulators.
Yasuhiro TANAKA Toshihisa HONMA
In order to effectively solve a three-dimensional unsteady convective diffusion equation, kernel approximation is introduced into the boundary integral procedure in the boundary-element method. It is shown that the present method gives a good approximate solution of the convective diffusion equation in case of not a dominant convection. Also, we find that very fast numerical integration can be carried out on supercomputers.
Mikihiro WATANABE Atsushi MATACHI Teruo ISHIBASHI Atsushi NOYA Shinya KURIKI
Y-Ba-Cu-O films sputter-deposited at about 650 in high oxygen concentration gas are superconductive without heat treatment after the deposition. The films of 700 nm thickness have Tc end of 72 K on SrTiO3 and 65 K on sapphire substrates. Reduced interdiffusion, compared with post-annealed films at high temperatures, between the film and the substrate is confirmed.
Osamu SHIMOMURA Hidetoshi ARII Mituhiro KURODA
Relationships between temperature and specific gravity of methanol solution of urea were measured under various concentration. Solubility and supersolubility curves to methanol were obtained. It was found that methanol is relatively suitable as solvent to the growth of urea crystal.
Osamu HIROTA Yoshihiro YOSHIDA Masao NAKAGAWA Mikio TAKAHARA
The advantage of nonstandard quantum states such as two-photon coherent state (or squeezed states) and photon number state as transmitter state is strongly degraded by transmission loss in quantum communications. To cope with such a problem, a new application of these states is proposed, and it is shown that its system has infinite capacity.
Tsuneo HORIGUCHI Nori SHIBATA Mitsuhiro TATEDA
A heterodyne interferometer utilizing a light source with short coherence length has led to a significant improvement in distance resolution of an optical reflectometer. The resolution less than 1 cm along a fiber is easily achieved by a Fabry-Perot type diode as a short coherence length source.
Souichi TSUKAMOTO Osamu FUJIWARA Kazuo KATOH Takashi AZAKAMI
This letter describes the occurrence-frequencies of the microarcs in the carbon sliding-contacts which are known to give the low radio-noises. A method is presented for statistically evaluating the arc occurrence-frequencies. The measurement results are also shown.
Kazuhiro SADO Yoshihide IGARASHI
Two fast parallel sorting algorithms on a mesh-connected model are described. These algorithms are some combinations of row and column sorts, and use just the compare-exchange as their basic operation. The computing time of the first algorithm for sorting n2 items is 6.5n+2 log n-5 steps and the computing time of the second one is not more than 5.5n+0.5 log n+0.5 +1.5 log n-3 steps. The control structures of these algorithms are particularly simple. The correctness of the algorithms are proved in a lucid way by using a function POTENTIAL. The function evaluates the exact number of steps to sort items by parallel bubble sort.