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排序方式: 共有382条查询结果,搜索用时 46 毫秒
91.
Katsuta G. Toya A. Ying Li Okashita M. Aida F. Ebinuma Y. Ohki Y. 《Dielectrics and Electrical Insulation, IEEE Transactions on》1999,6(6):887-891
Through investigations made on crosslinked polyethylene (XLPE) insulated power cables that had experienced failures, blue-colored water trees were observed in addition to ordinary white water trees. The blue water tree was found to be much more harmful than the white water tree, since more electrical trees started at the blue trees. Elemental analysis revealed that iron and sulfur exist in the blue tree. In the case of this blue water tree, space charge exists abundantly but only at the tree tip, while no charge signal is observed on the electrode from which the tree starts. This indicates that the conductivity of the blue tree is very high. This is considered to be the main reason of the harmfulness of this tree 相似文献
92.
Bacterial community structures in MBRs treating municipal wastewater: relationship between community stability and reactor performance 总被引:9,自引:0,他引:9
Bacterial community structures in pilot-scale conventional membrane bioreactors (CMBRs) and hybrid MBRs (HMBRs) which were combined with pre-coagulation/sedimentation were analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and fluorescence in situ hybridization (FISH) techniques. The results were compared with the community structure in a full-scale activated sludge (AS) process treating the same municipal wastewater. The Dice index (Cs) of similarity analysis of DGGE banding patterns demonstrated that the microbial community in AS was more similar to those in CMBR1 and CMBR2 than HMBR1 and HMBR2. This suggested that influent wastewater composition had a larger impact on bacterial community structures. Long-term community structure changes in the HMBRs and CMBRs were monitored and analyzed over 240 days by Non-metric multidimensional scaling (NMDS) analysis of DGGE banding patterns. The NMDS analysis revealed that both HMBRs and CMBRs had marked changes in community structures during the first about 100 days. Thereafter the perpetual fluctuations of bacterial community structures were observed in both HMBRs and CMBRs, even though the stable MBR performances (the performance was measured as membrane permeability and removal of dissolved organic carbon, DOC) were achieved. These results suggest that not only the stability, but also the adequate dynamics ("flexibility") of the bacterial community structure are important for the stable performance of the MBRs treating complex municipal wastewater. 相似文献
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Professors Inuishi, Ieda and Yahagi were pioneers of research in dielectrics in Japan. Their philosophy was that in order to understand a certain property of a material or to clarify the mechanism of a phenomenon, research must be done with scientific rigor and a scholarly approach. Here, the author wishes to illustrate their philosophy through a number of examples of his own research on both inorganic and organic materials and on topics ranging from vacuum discharge, through defect centers in inorganic glasses, to the water tree degradation phenomena in insulating polymers. Finally he will make some comments upon the way in which fundamental research can be useful in an engineering context. 相似文献
96.
Katsumi Yamazaki Shunji Ohki Akira Nezu Takeshi Ikemi 《Electrical Engineering in Japan》2009,168(3):59-66
In this paper, we present the development of interior magnet motors reducing iron loss at high rotational speed under the flux weakening control. The rotor core and magnet shapes are determined by the automatic numerical calculation using combination of the optimization method and the adaptive finite element method. The optimized motor is manufactured to prove the effectiveness by the measurement of the iron loss. Both results of the calculation and the measurement indicate that the iron loss of the proposed motor at the high rotational speed under the flux weakening control is reduced by half compared with the initial rotor shape while the torque is nearly constant. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(3): 59–66, 2009; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20827 相似文献
97.
Crosslinking junctions of vulcanized natural rubber were analyzed by solid-state NMR spectroscopy equipped with a field-gradient high speed magic angle spinning probe. Resolution of 1H and 13C NMR spectra and correlations between 1H and 13C of the vulcanized natural rubber were investigated by one- and two-dimensional measurements, including inverse correlation measurements. The number of substitution of the carbon atom at the crosslinking junctions was determined by solid-state NMR spectroscopy. 相似文献
98.
Kim E.J. Takeda T. Ohki Y. 《Dielectrics and Electrical Insulation, IEEE Transactions on》1996,3(3):386-391
In order to understand the dominant carrier species in electrical conduction in polyethersulfone (PES), thermally stimulated current (TSC) measurements were carried out under various conditions. It was found that PES has two TSC peaks in the temperature range from 20 to 220°C, consisting of an α peak at ~210°C and a β peak whose peak temperature moves towards a higher temperature with an increasing poling temperature. Even when the sample was not poled, PES shows a spontaneous current with its peak at ~210°C. Both the spontaneous current peak and the α peak were found to disappear when the sample had been heated to 230°C, keeping the external circuit closed. From such similarity of appearance and disappearance between the two peaks, it is concluded that they have the same origin. From the change in the spatial distribution of space charges inside the sample measured simultaneously with the TSC measurements, positive charges, probably due to K+ ions, existed nonuniformly in the sample from the beginning, and are thought to be responsible for the two peaks. From a similar study, the β peak is considered to be due to polarization of ionic space charges during the poling process 相似文献
99.
Yoshimasa Takahashi Itaru Ashida Shigeo Arai Kimitaka Higuchi Yuta Yamamoto Shunsuke Muto 《International Journal of Fracture》2018,209(1-2):223-229
In this study, we have investigated microstructures of the delamination cracks observed from tensile and fracture toughness test specimens using an API X70 pipeline steel. It is found that the delaminations observed from both tensile and toughness specimens are intergranular fractures. At the occurrence, characteristics of brittle fracture were observed, but it was found not to be a brittle fracture as the delaminations were induced by plastic deformation. It is shown that severe plastic deformation produced strain concentration around particles located along grain boundaries and caused decohesion between adjacent grains, resulting in intergranular fracture. 相似文献
100.
Tamaoki Haruhiko; Kobayashi Yuji; Nishimura Shigenori; Ohkubo Tadayasu; Kyogoku Yoshimasa; Nakajima Kiichiro; Kumagaye Shin-ichiro; Kimura Terutoshi; Sakakibara Shumpei 《Protein engineering, design & selection : PEDS》1991,4(5):509-518
The structure of endothelin-1 (ET-1), an endothelial cell-derivedpeptide with vasoconstricting activity, was determined in anaqueous solution by means of a combination of NMR and distancegeometry calculations. The resulting structure is characterizedby an -helical conformation in the sequence region, Lys9-Cys15.Furthermore, an extended structure and a turn structure existin the Cys1-Ser4 and Ser5-Asp8 regions respectively, and nopreferred conformation was found for the C-terminal part ofthe peptide which was not uniquely constrained by the NMR data.These structural elements, the -helical structure in the sequenceportion, Cys-X-X-X-Cys, and the extended structure in Cys-X-Cys,are homologous to those found commonly in several neurotoxicpeptides. 相似文献