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31.
32.
Urata C Yamauchi Y Aoyama Y Imasu J Todoroki S Sakka Y Inoue S Kuroda K 《Journal of nanoscience and nanotechnology》2008,8(6):3101-3105
A new type of hierarchically porous materials is fabricated by assembling mesoporous nanoparticles via spray drying. Well-dispersed mesostructured silica nanoparticles (MSN), whose particle size distribution was narrow in the range of 20 nm and 50 nm, were prepared by a thermal deposition method. By spray drying a MSN suspension, MSN were assembled into spherical secondary particles. After calcination, the spherical particles have two types of mesopores, mesopores of 3 nm in size inside of calcined MSN and larger inter-nanoparticle mesopores of about 15-20 nm. This hierarchical pore system should provide nanospaces for efficient mass transport of guest species with different sizes. 相似文献
33.
The separation–permeation performance of porous silicon nitride (Si3N4) ceramics (consisting of columnar grains connected at random in three dimensions) as membrane filters was evaluated, and compared with commercial Al2O3 membranes having a three-layer structure. Si3N4 membranes separate particles with diameters much less than their pore diameters. The permeability of Si3N4 membranes with separability values the same as those of the Al2O3 membranes was about 1.3–2.4 times as large as the Al2O3 membranes. Dead-end filtration examination, using Al2O3 particles with a particle size distribution, indicated that the Si3N4 membrane filtration mechanism obeyed the cake filtration mechanism although the particle size was smaller than the pore size of the Si3N4 membranes. 相似文献
34.
Takaharu Ishida Osamu Kubo Chihiro Fukui Yutaka Kokai Shigeo Mizutani Makoto Yamamoto Toshiaki Takayama 《Electrical Engineering in Japan》1998,125(1):18-26
Voltage–reactive power control (VVC) on power systems becomes difficult when a load increases or decreases rapidly, especially in the morning and at noon. This is caused mainly by two problems. One is delayed operation and the other is noncooperative operation of facilities. To solve these problems, an advanced method and algorithms for a centralized feed-forwarding control system are presented. They are based on two main steps: forecasting the power system state for several minutes and dispatching reactive power sources optimally based on stepwise linear programming. The proposed method is evaluated and tested for data of a large-scale power system. The results show that the proposed method keeps the voltage constraints well and reduces redundant operation of facilities. © 1998 Scripta Technica, Electr Eng Jpn, 125(1): 18–26, 1998 相似文献
35.
Shigeyuki Sugimoto Junzo Kida Hiroshi Arita Chihiro Fukui Tokio Yamagiwa Yoshihiro Murai 《Electrical Engineering in Japan》1999,127(1):11-22
Recently, expansion in the scale of power systems and development of localized power sources are leading to an increase in fault current of 500‐kV systems. In the future, it is quite likely that the fault current at the interconnection of such power systems may exceed the rated short‐time current of existing electric power facilities. As one of the solutions of this problem, a thyristor‐controlled series‐resonant‐type fault current limiter (FCL) is proposed to restrain the fault current. This paper deals with the FCL system configuration, the placement method of the FCL in power systems, the outline of the FCL's specification, and the operation method of the protective relay in the multimachine system. Finally, the effectiveness of the FCL is evaluated from the viewpoints of limiting the fault current by simulation analysis. The FCL is shown to be a useful protection device for large, high‐capacity power systems. © 1999 Scripta Technica, Electr Eng Jpn, 127(1): 11–22, 1999 相似文献
36.
Akira Kishimoto Yasuki Kansha Chihiro Fushimi Atsushi Tsutsumi 《Clean Technologies and Environmental Policy》2012,14(3):465-474
The integrated coal gasification combined cycle (IGCC) can achieve higher power generation efficiency than conventional pulverized coal combustion power plants. However, a CO2 capture process prevents improving power generation efficiency of IGCC, because CO2 separation from gas mixtures requires huge amounts of energy. Therefore, in this study, we analyzed the CO2 separation process in the pre-combustion capture process using a process simulator (PRO/II) in the steady state, and proposed a new process using a modularity based on self-heat recuperation (SHR) technology to decrease energy consumption. Pre-combustion capture was applied in the IGCC plant, which involved coal gasification and CO-shift conversion with CO2 capture. The results show that the energy consumption for the CO2 separation process using SHR was decreased by two-thirds. This means that the power generation efficiency can be improved by SHR compared with conventional IGCC with a CO2 capture process. 相似文献
37.
Ranfeng Qiu Hongxin Shi Keke Zhang Yimin Tu Chihiro Iwamoto Shinobu Satonaka 《Materials Characterization》2010,61(7):684-688
The interfacial characteristics of resistance spot welded steel–aluminum alloy joint have been investigated using electron microscopy. The results reveal that reaction product FeAl3 is generated in the peripheral region of the weld while a reaction layer consisting of Fe2Al5 adjacent to steel and FeAl3 adjacent to aluminum alloy forms in the central region of the weld, and that the morphology and thickness of the reaction layer vary with the position at the welding interface. 相似文献
38.
Kenji Nakamura Shinobu Satonaka Yoshiki Matsunaga Masahiro Kuronaga Chihiro Iwamoto 《Welding International》2017,31(6):435-444
In this study, new butt welding technique was proposed to join polymeric materials in which the polymeric material is softened by a heated tool due to the Joule effect heating of the electric current flow through the tool, and the coalescence of material is done by the stirring action due to the tool rotation. A 3 mm-thick Polycarbonate (PC) sheets were joined in various joining conditions, from which joining mechanism, mechanical properties of joints and process parameters affecting joint performance were investigated. In the experiments, in situ observation with a CCD camera and material temperature measurement during the process, as well as the observation of surface appearance and cross section of the joint and tensile test were performed for these purposes. It was shown from the in situ observation and material temperature measurement that the molten and softened region is formed around the weld tool. It was also shown that sufficient heat input was required to form sound joints with acceptable performance, which depended upon the joining speed and amount of electric current flow through the tool. The observation of joint appearance and cross section revealed that the joint with comparable thickness to base material was obtained under the condition of revolution pitch below 0.08 mm, defined by the ratio of joining speed to tool rotation. It is noticed that joints obtained from the proper conditions have the same mechanical properties as the base material, and that the process parameters of this method were tool rotation speed, welding speed and amount of electric current. These results suggest proposed method is useful for joining the polymeric materials. 相似文献
39.
Yuji Yoshie Masanori Ishizuka Guoqing Guan Chihiro Fushimi Atsushi Tsutsumi 《Advanced Powder Technology》2013,24(2):487-494
A novel method for directly measuring the temperature history of mobile hot ferromagnetic particles (steel particles), substituting for reacting particles, in a binary-solid (reacting particles and inert particles) downflow is introduced. The temperature history of the hot steel particles can be obtained by measuring the temperature of the particles at different axial positions using magnetic fields that can separate the steel particles from other bed materials immediately and easily. Employing the magnetic marking method, magnetic sensors were used to detect the change in magnetic flux density in a given magnetic field, and the residence time of the steel particles was also measured. The cross-sectional averaged particle-to-bed heat transfer coefficients were calculated from the experimental results using simple heat balance equations. The measured temperature data have a relatively wide error range; however, the average temperature curves derived from the average particle-to-bed heat transfer coefficients agreed with the temperature plots. Therefore, the experimental method of this study is applicable to the measurement of the particle temperature in a binary-solid downflow. The results showed that there is strong correlation between the particle-to-bed heat transfer coefficients and normalized collision frequency under the laminar gas flow conditions. 相似文献
40.
ZdenĚK Slanina Chihiro Miyajima Xiang Zhao Filip Uhlík Ludwik Adamowicz Eiji Obarsawa 《Fullerenes, Nanotubes and Carbon Nanostructures》2013,21(4-5):385-402
Abstract Semiempirical quantum-chemical PM3 calculations are reported for a relatively new class of exohedral metallo-fullerenes - metal-coated or metal-covered fullerenes: C60Mn. The exohedral species were recently observed, however, their geometrical and electronic structure is not known yet. In this paper, relatively-even metal-atom distributions over the fullerene rings are considered - such regular forms are computed for M= Be, Mg, Al. Three selected stoichiometrics are treated: C60M12, C60M20, and C60M32. The stoichiometrics correspond to the location of the metal atoms above the twelve pentagons, above the twenty hexagons, and above each of the thirty two rings of C60 This interesting arrangement over the rings is possible only for some types of atoms, while other elements are localized above bonds or atoms, or inside the cage, or even react and destroy the cage. Other limitation comes from the parametrization of the computational methods - the computations are performed with the PM3 semiempirical method and metal-layer atomization heats are used as a stability measure. Structural characteristics are presented, too. Considerable reductions of the cage symmetry are reported and their relationships to Jahn-Teller effect are discussed, too (no case of the icosahedral symmetry is found). 相似文献