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22.
Hiromasa Higasa Ryoichi Takahata Hiroshi Imaizumi Kenzo Miya 《Electrical Engineering in Japan》1996,116(3):96-106
A high-temperature superconductor YBa2Cu3O7-x with strong pinning force has allowed stable magnetic suspension with no control to be developed. Two types of superconducting magnetic bearings (SMB) using YBCO and permanent magnet were assembled. The two types are radial and axial. The dynamic stiffness of each SMB as it was cooled down under a magnetic field by liquid nitrogen was measured both radially and axially. As a result, it was found that the spring constants of these SMBs were almost as large as a practically desirable value; however, their damping coefficients were lower than the practical level. These findings are useful as one of the data bases for development of an optimum SMB design to support the weight of rotors in an axial direction. 相似文献
23.
Motonobu Yoshikawa Hiroshi Nakajima Takeshi Inada Yasushi Harada Masahiko Amano Yuji Nakata 《Electrical Engineering in Japan》1995,115(7):29-39
A new practical method is proposed which gives a quasi-optimal solution of the dynamic load-dispatching problem formulated by a multiconstraint multiobjective optimization problem. Here, the multiple constraints are rate reserve constraints and power flow ones, and the multiple objectives are fuel cost and CO2 emission. The proposed method is an integration of the following three techniques: (1) “Group Dispatch Scheme,” which is developed by the authors, is used to satisfy a violated constraint easily. This scheme consists of three steps. The first step is to classify all generators into two groups. One is the group which should be more loaded to satisfy the violated constraint, and the other is the should-be less loaded group. The second step is to add some load to the former group, and to subtract the same load from the latter. The third step is to dispatch each group load to each groups generators, respectively; (2) the dynamic load-dispatching algorithm is used which provides, in practical time, quasi-optimal generation trajectories; (3) the conventional weighting parametric method is used to obtain a Pareto optimal solution of multiobjective problems. The effectiveness of the method is clarified by a computer simulation on the actual power system of Kansai Electric Power Company. 相似文献
24.
25.
R. Kamimura 《Algorithmica》1998,22(1-2):173-197
26.
Hideaki Itoh Shigeharu Naka Tsuneaki Matsudaira Hiroshi Hamamoto 《Journal of Materials Science》1990,25(1):533-536
A sintered compact of titanium diboride (TiB2) was prepared by hot pressing of the synthesized TiB2 powder, which was obtained by a solid-state reaction between TiN and amorphous boron. Densification of the sintered compact occurred at 20 MPa and 1800° C for 5 to 60 min with the aid of a reaction sintering, including the TiB2 formation reaction between excess 20 at % amorphous boron in the as-synthesized powder (TiB2 + 0.2B) and intentionally added 10 at % titanium metal. A homogeneous sintered compact of a single phase of TiB2, which was prepared by hot pressing for 30 min from the starting powder composition [(TiB2 + 0.2B) + 0.1 Ti], had a fine-grained microstructure composed of TiB2 grains with diameters of 2 to 3 m. The bulk density was 4.47 g cm–3, i.e. 98% of the theoretical density. The microhardness, transverse rupture strength and fracture toughness of the TiB2 sintered compact were 2850 kg mm–2, 48 kg mm–2 and 2.4 MN m–3/2, respectively. The thermal expansion coefficient increased with increasing temperature up to 400° C and had a constant value of 8.8 x 10–6 deg–1 above 500° C. 相似文献
27.
Constant stress creep under compression stress, 100 to 316 MPa, at 1100 K was investigated on single-phase TiAl intermetallics. The material was ingot-cast, isothermally forged, and then annealed to produce stable equi-axed grain structures, whose average grain diameters were 25, 42 and 70m. Creep curves were very similar among the three specimens with different grain diameters and the creep rates at a given strain, as well as the minimum creep rates, depended little on grain size. Two regimes were observed on the stress dependence of the minimum creep rate. The stress exponent under high stresses was about 4.5, independent of grain size. Under stresses lower than about 150 MPa it became about 8. 相似文献
28.
Akihiro Yamada Kuniko Kojima Koji Minami Hiroaki Sugiura Hiroshi Kida Kenji Samejima 《Journal of the Society for Information Display》2012,20(7):390-396
Stationary projectors mainly used in system applications have recently gained a wider application range, including general presentations in halls and large conference rooms and being used, for example, in digital signage and for monitoring purposes. Consequently, they are required to meet new market demands for durability, reliability, and flexibility in installation in addition to their conventional basic performance such as especially high brightness. To achieve especially high brightness, a new optical system with two lamps is proposed; the profile of the cover glass that prevents the glass from scattering is made aspherical, the profile of the beam‐combining mirror is improved with its position optimized, and the size of the incident plane of the integrator rod is made larger (1.1 times). These measures resulted in an optical system of an even higher efficiency with 7000 lm, which is the highest in its class (according to a June 2010 investigation). Also, the arrangement of two parallel lamps completely eliminated the effect of heat passing from one lamp to the other, which helped secure durability, reliability, and flexibility in installation. Furthermore, the combined use of the unique non‐telecentric optical system, adopted from the conventional single‐lamp model, helps maintain the class‐highest contrast ratio.1,2 相似文献
29.
Takeshi Kikuchi Yoshizo Kitami Masato Yokoyama Hiroshi Sakai 《Journal of Materials Science》1989,24(12):4275-4278
The phase equilibria in the pseudo-binary system Bi2O3-TeO2 at 600° 950° C in air were examined by solid-state reaction techniques and X-ray powder diffraction method. Four pseudo-binary compounds appeared, i.e., -Bi2O3 type solid solution having a compositional range of (1-x)Bi2O3·xTeO2 wherex=0 0.4 a new compound Bi6Te2O15 which has an orthorhombic cell of a=2.27(4) nm, b=1.06(1) nm and c = 0.539(8) nm, 2Bi2O3 · 3TeO2, and an unidentified phase Bi2O3·2TeO2. The formation of the phase Bi6Te2O15, in which all the Te ions are hexavalent, was confirmed by the thermogravimetry and by the Mössbauer spectra. The liquidus curves for whole system were determined by DTA method. 相似文献
30.
Isao Mochida Hiroshi Toshima Yozo Korai Tsutomu Naito 《Journal of Materials Science》1988,23(2):678-686
Polyphenyleneoxide was blended in amounts of 5 or 10 wt% into petroleum-derived mesophase pitch to reinforce the pitch fibre before the oxidative stabilization to achieve better handling properties. Although polyphenyleneoxide was fusible but hardly soluble in the mesophase pitch even at a spinning temperature of 350° C, blended pitch could be smoothly spun into pitch fibre 10m diameter, as could the parent pitch. Fibrous polyphenyleneoxide of less than 1m diameter was homogeneously dispersed in the pitch fibre, being arranged along the fibre axis. Such fibrous polyp henyleneoxide reinforced the pitch fibre considerably. The fibrous substances at the centre of the fibre disappeared in the carbonized fibre at 1300° C after oxidation at 250° C, although some short ones were observed in the skin region of the fibre, suggesting that polyphenyleneoxide was co-carbonized to be assimilated with mesophase pitch at the centre of the fibre, where the effects of oxidation may be rather limited. The oxidation reactivity and its mechanical strength after carbonization were slightly lower in comparison with those of the parent mesophase pitch. 相似文献