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排序方式: 共有363条查询结果,搜索用时 15 毫秒
351.
Jun Oyama Tsuyoshi Higuchi Ryuta Tsukamoto Takehisa Haraguchi Eiji Yamada Takashi Koga 《Electrical Engineering in Japan》1994,114(7):124-134
The matrix converter proposed by Venturini is very simple in structure and has powerful controllability. However, there are few applications especially in power electronics fields. This seems to be caused mainly by the fact that such power devices that were fast enough to suppress ringing oscillations in the supply lines and large enough to pay for more devices and more complicated control circuits than in conventional dc-link converter-inverter systems were not available. At present, static induction thyristors (SIThs) have been introduced and a new possibility for the matrix converter has been raised. This paper describes a new control strategy which is simple and practical and allows the output voltage of 0.866 times the supply voltage to be generated. Also, the new firing sequences which eliminate voltage and current spikes are proposed. Steady-state and distortion characteristics of the prototype PWM matrix converter with SITh are shown. 相似文献
352.
353.
354.
Sugibayashi T. Naritake I. Utsugi S. Shibahara K. Oikawa R. Mori H. Iwao S. Murotani T. Koyama K. Fukuzawa S. Itani T. Kasama K. Okuda T. Ohya S. Ogawa M. 《Solid-State Circuits, IEEE Journal of》1995,30(11):1277-1280
A time-shared offset-canceling sensing scheme, a defective word-line Hi-Z standby scheme, and a flexible multimacro architecture have been developed for 1-Gb DRAM. These circuit technologies have been applied to a 1-Gb DRAM for file applications employing 0.25 μm CMOS process technology, a diagonal bit-line cell, and a two-stage pipeline circuit technique. In this DRAM, a 30% chip size reduction and a 400-MB/s data transfer rate have been achieved. A 100% improvement in yield has been estimated by Monte-Carlo simulation. The 1-Gb DRAM die size is 936 mm2. The cell size is 0.54 μm2. The operating current is 58 mA at 2 V and 100 MHz 相似文献
355.
Scattering angle dependence of the signal/background ratio of Si K-shell and A1 K-shell electron excitation losses has been measured for single crystals and evaporated films. The ratio changed periodically with the scattering angle, and maxima were found to be located between Bragg reflections including the center beam. Thus the ratio is improved between the Bragg reflections and just outside the incident beam, which is very important as a practical technique for elemental analysis in the higher energy loss region in EELS. 相似文献
356.
Takehisa Kohda Hiromitsu Kumamoto Koichi Inoue Isao Takami 《Microelectronics Reliability》1982,22(3):445-456
The sensor system has two types of contradictory failures; a fail-dangerous failure and a fail-safe failure. A method of obtaining the optimal structure is developed for the sensor system which is composed of general components. The optimal structure minimizes an expected damage, considering all possible boolean structures including noncoherent systems. A simple optimality criterion is obtained and several properties of the optimal structures are derived; a noncoherent structure can be optimal in some cases. A simple systematic search algorithm can be used effectively to determine the optimal system. Analytic solutions are obtained for systems composed of identical components. Illustrative examples are given. 相似文献
357.
E. Kandyel T. Kamiyama K. Oikawa S. Torii K. Mori H. Asano M. A. Sekkina 《Journal of Superconductivity》2000,13(1):111-119
Two series of Hg-based oxides (Hg0.7Mo0.3)Sr2(Ca1–x
R
x
)Cu2O
z
(R = Nd and Pr, 0.2 x 0.7) have been synthesized. Electrical-resistivity measurements show that these compounds are superconductors with maximum onset T
c
of 107 and 102 K for Nd- and Pr-containing samples, respectively. The neutron powder diffraction experiments on both as-prepared and O2-annealed samples of R = Nd revealed that the O(3) site at the HgO sheets are fully occupied and shifted towards the Hg/Mo site to form Mo–O bonds. 相似文献
358.
Hiroshi Funakubo Shintaro Yokoyama Tomohiko Ozeki Atsushi Nagai Takahiro Oikawa 《Science and Technology of Advanced Materials》2013,14(4):431-435
{100} One-axis-oriented PZT films with a thickness of 2 μm were obtained on (111)Pt/TiO2/SiO2/(100)Si substrates by metal organic chemical vapor deposition (MOCVD). These were obtained irrespective of the film thickness up to 2 mm and with a Zr/(Zr + Ti) ratio from 0.20 to 0.75. This was found to be due to the higher growth rate of these orientation grains than {110} and {111)} orientation grains. These films had columnar grains 50–100 nm in width. Moreover, they were found to include 908 nano-domains 10–20 nm in width. Dielectric constant, εr and the field induced-strain were maximum around a Zr/(Zr + Ti) ratio of 0.5, which was in good agreement with previous reports on sintered bodies with 100 times larger domains. This means that the domain size had any effect on εr or field-induced strain. 相似文献
359.
Suzuki M Kasai H Ishizaka T Miura H Okada S Oikawa H Nihira T Fukuro H Nakanishi H 《Journal of nanoscience and nanotechnology》2007,7(8):2748-2752
Polyimide particles were fabricated through the two-steps imidization of poly(amic acid) particles prepared by using reprecipitation method. PAA and PI nanoparticles were all spherical, and the changes of particle size, its distribution, and morphology were not observed before and after the imidization. The preparation of PI nanoparticles size-controlled between ca. 20-500 nm was also achieved by changing the experimental conditions, temperature of the poor solvent, the composition of two kind of poor solvent, and PAA-NMP solution concentration. 相似文献
360.
Takehisa Mochizuki Daichi Hongo Takuya Satoh Naoto Koizumi Muneyoshi Yamada 《Catalysis Letters》2008,121(1-2):52-57
Co/SiO2 catalysts were prepared by a stepwise impregnation of aqueous solutions containing Co nitrate or chelating agent, nitrilotriacetic
acid (NTA) or trans-1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid (CyDTA), with various concentrations of Co2+ and the chelating agent. Fischer–Tropsch synthesis activity of Co/SiO2 catalysts having Co loadings of 5–20 mass% as metallic Co was improved by the stepwise impregnation method with these chelating
agents. The catalyst prepared with CyDTA (Co loading = 20 mass%, Co2+/CyDTA = 4 mol mol−1) yielded 1,500 and 815 g kg-cat−1 h−1 of C5+ and C10–20 hydrocarbons at 503 K and 1.1 MPa, respectively, which was much greater than that with the catalyst prepared from the aqueous
solution containing both Co nitrate and NTA. 相似文献