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21.
Hachijojima is a gourd-shaped volcanic island in the Pacific Ocean. Nishiyama and Higashiyama volcanoes consist of basalt lava and associated pyroclastic rocks. A promising geothermal resource was found in south Higashiyama, associated with an uplift of Tertiary rocks consisting of mainly andesite lava and related pyroclastic rocks, overlain by Quaternary volcanic rocks. Steep high-temperature (over 250°C) and high-pressure gradients occur in the deeper portion of the system near the Tertiary–Quaternary contact, indicating the presence of a cap rock. The cap rock formed by deposition of hydrothermal minerals. Geothermal fluid ascends from the deeper portions to shallow depths along vertical fractures through the cap rock. These vertical fractures form the geothermal reservoir in the Tertiary formation. Three wells were drilled into these vertical fractures, and approximately 30 t/h of superheated steam was obtained from each well during flow tests. The geothermal fluid is mainly a mixture of seawater and meteoric water in an approximate ratio of 1 to 2, based on chemical analyses, with a portion of volcanic gas included. At present a 3.3 MWe, geothermal power plant is being constructed here. 相似文献
22.
Katsuyuki Umezawa Seiichi Susaki Satoru Tezuka Shigeichi Hirasawa 《IEEJ Transactions on Electrical and Electronic Engineering》2007,2(1):84-93
We have developed a public key certificate validation system considering the restrictions peculiar to the mobile environment, such as processing the speed and memory capacity of a cellular‐phone terminal, and the network transmission speed. In this paper we derive a theoretical formula showing the performance of a validity check of the public key certificate of the conventional system and of the proposed system, and compare and examine a theoretical value in a mobile environment. Moreover, we evaluate the actual measurement that uses the server and cellular‐phone terminal that we developed. We show that our proposed system based on the certificate validation server (CVS) system is better than the conventional system from the viewpoint of processing speed and transmission speed. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
23.
Yosuke Ue Ryoichi Hara Hiroyuki Kita Yutaka Saito Katsuyuki Takitani Masami Saito 《Electrical Engineering in Japan》2012,180(3):55-63
Photovoltaic (PV) systems are attracting attention as one of the promising countermeasures against global warming and the environmental issues. However, the generation output from PV systems is generally unstable and unpredictable. Therefore, large penetration of PV systems may cause some serious impacts on power system operation, such as load frequency control, voltage regulation, etc. Estimation of the influences of PV system installation is becoming important, but it requires simultaneous multipoint solar radiation measurements. The Japan Meteorological Business Support Center has provided 1‐minute meteorological data observed in Japan, but its solar radiation data includes quantization errors. This paper proposes a regeneration method for solar radiation data including quantization errors. It also analyzes the spatial smoothing effect of global solar radiation fluctuations. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(3): 55–63, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21274 相似文献
24.
Hiroshi Funaakubo Masatoshi Mitsuya Norimasa Nukaga Katsuyuki Ishikawa 《Integrated ferroelectrics》2013,141(1-4):225-234
Abstract SrBi2(Ta0.7Nb0.3)2O9 (SBTN) films were first prepared on (111)Pt/Ti/SiO2/Si substrates by MOCVD from only two organometallic source bottles. Bi(CH3)3 and the mixture of Sr[Ta(O°C2H5)6]2 and Sr[Nb(O°C2H5)6]2 were used as source materials. High compositional reproducibility was obtained; the Nb/(Ta+Nb) ratio was the same as the mixing ratio of the source. Sr/(Ta+Nb) and Bi/(Ta+Nb) ratios can be controlled by the reactor pressure and the input gas flow rate ratio of the source gases. Almost single phase of SBTN was obtained for the film deposited at 500°C and the following heat-treated at 800°C in O2 atmosphere. Pr and Ec values of 330 nm-thick SBTN film were 8.5 μC/cm2 and 91 kV/cm, respectively and were larger than those of SrBi2Ta2O9 film. There was no degradation after 5x1010 cycles polarization switching. 相似文献
25.
26.
Mikihiko Endo Tomonori Koyama Yousuke Takahashi Katsuyuki Kaiho Satoru Yanabu 《Electrical Engineering in Japan》2010,173(4):20-27
Using a high‐temperature superconductor, we constructed and tested a model Superconducting Fault Current Limiter (SFCL). The SFCL that we proposed has a vacuum interrupter with electromagnetic repulsion mechanism. We set out to construct a high‐voltage‐class SFCL. We produced an electromagnetic repulsion switch equipped with a 24‐kV vacuum interrupter (VI). However, the opening speed becomes slower, because the larger vacuum interrupter needs a heavier‐weight contact. For this reason, the current which flows in a superconductor may not be interruptible within a half cycle of current. In order to solve this problem, it is necessary to change the design of the coil connected in parallel and to strengthen the electromagnetic repulsion force at the time of opening the vacuum interrupter. Thus, the design of the coil was changed, and in order to examine whether the problem is solvable, a current limiting test was conducted. We carried out a current limiting test using second‐generation (2G) HTS wire. The element used in this experiment has a stainless steel stabilizer on both sides of the wire. In the experiment we succeeded in interrupting the current of a superconductor within a half cycle. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(4): 20–27, 2010; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21039 相似文献
27.
Tatsushi Saito Tatsuya Yokoi Atsutomo Nakamura Katsuyuki Matsunaga 《Journal of the American Ceramic Society》2020,103(9):5354-5364
First-principles calculations were performed to examine defect formation energies and site preference of substitutional divalent cations M2+ (M = Mg, Cu, Zn, Cd, Sr, Pb, and Ba) in hydroxyapatite (HAp, Ca10(PO4)6(OH)2) and carbonated apatite (CAp). All inequivalent substitutional sites of and M2+ were investigated to determine their most preferential sites. For all M2+ studied, their defect formation energies for the most stable substitutional sites were lower in CAp than in hydroxyapatite (HAp), demonstrating that M2+ are preferentially substituted into CAp over HAp. For Ca sites in CAp, correlations between the defect formation energies and Ca-O bond lengths showed that bigger and smaller M2+ than Ca2+ are preferentially substituted for Ca sites with longer and shorter bond lengths than those in HAp, respectively. In addition, Ca sites with lower coordination numbers than 6 are preferentially substituted by Zn2+ and Cu2+ that originally tend to form 4- or 5-fold coordination in their phosphate crystals. substitution is therefore likely to effectively stabilize substitutional foreign ions by modifying bond lengths and coordination numbers of Ca sites from those in pure HAp. These effects may play an important role in enhancing the M2+ solubility into CAp. 相似文献
28.
Tetsuji Hirato Hiroshi Majima Yasuhiro Awakura 《Metallurgical and Materials Transactions B》1987,18(1):31-39
A comparative study of electrochemical leaching and chemical leaching of chalcopyrite was performed mainly at 343 K to elucidate
the leaching mechanism of chalcopyrite with CuCl2. Also, the morphology of the leached chalcopyrite surface was studied by using a single chalcopyrite crystal. The leaching
with CuCl2 produced a porous elemental sulfur layer on the chalcopyrite surface, showing a similar morphology to that produced during
leaching with FeCl3. The leaching kinetics were found to be linear over an extended period, followed by an acceleration stage, as a result of
an increase in the reaction surface area. The leaching rate of chalcopyrite was proportional to C(CuCl2)0.5, whereas it was inversely proportional to C(CuCl)0.5. The mixed potential of chalcopyrite exhibited a 66 mV decade−1 dependency upon C(CuCl2), and—69 mV decade−1 upon C(CuCl). Based on these observations together with other findings, an electrochemical mechanism involving the oxidation
of chalcopyrite and CuCl
−
2
and the reduction of CuCl+ was proposed. The Tafel plot between the mixed potential and the current density obtained by converting the rate of chemical
leaching gave a straight line whose slope was in good agreement with that of the electrochemical leaching. These findings
strongly support the electrochemical mechanism of chalcopyrite leaching with cupric chloride. 相似文献
29.
Katsuyuki Matsunaga Fumiyasu Oba Isao Tanaka Hirohiko Adachi 《Journal of Electroceramics》1999,4(1):69-80
Discrete variational (DV) Xα cluster method has been employed in calculating electronic structures of ZnO. Electronic structures of the bulk and the non-polar surface model clusters are calculated with inclusion of electrostatic potentials in the bulk and near the surface, and the electronic origins of experimental spectra and chemical bonds at the surface are examined in detail. The valence band structure constructed by Zn-3d and O-2p bands is much influenced by electrostatic potentials in ZnO. It is found that the reduction of an electrostatic potential near the surface gives rise to the difference of the valence band structures between in the bulk and at the surface. The calculated density of states at the non-polar surface of ZnO, where the Zn-3d and O-2p bands are more widely separated than in the bulk, is in good agreement with the experimental UPS. In addition, a Zn-O bond at the surface is found to show stronger covalency than that in the bulk, as a result of the change of the valence band structure due to the effect of the electrostatic potential. 相似文献
30.
Hideki Taguchi Katsuyuki Nakade Masashi Yosinaga Masaki Kato Ken Hirota 《Journal of the American Ceramic Society》2008,91(1):308-310
X-ray photoelectron spectroscopy was performed to elucidate the catalytic activity of CH4 oxidation on perovskite-type Ca(Mn1− x Ti x )O3−δ synthesized at 1173 K in a flow of oxygen from a gel with citric acid and ethylene glycol. The Mn ion content decreases and the ratio of the Mn3+ ion in the Mn ion increases with increases in x . Ca(Mn1− x Ti x )O3−δ has a high catalytic activity of CH4 oxidation at x =0.4. These results indicate that the catalytic activity strongly depends on the Mn3+ ion content of the surface. 相似文献