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981.
Ichiro Komura Taiji Hirasawa Satoshi Nagai Jun-ichi Takabayashi Katsuhiko Naruse 《Nuclear Engineering and Design》2001,206(2-3)
Improvements in defect detection and sizing capabilities for non-destructive inspection techniques have been required in order to ensure the reliable operation and life extension of nuclear power plants. For the volumetric inspection, the phased array UT technique has superior capabilities for beam steering and focusing to objective regions, and real-time B-scan imaging without mechanical scanning. In contrast to the conventional UT method, high-speed inspection is realized by the unique feature of the phased array technique. A 256-channel array system has developed for the inspection of weldment of BWR internal components such as core shrouds. The TOFD crack sizing technique also can be applied using this system. For the surface inspection, potential drop techniques and eddy current techniques have been improved, which combined the theoretical analysis. These techniques have the crack sizing capability for surface breaking cracks to which UT method is difficult to apply. This paper provides the recent progress of these phased array and electromagnetic inspection techniques. 相似文献
982.
Taizo Sano Masamichi Tsuji Nobuyuki Gokon Hiroshi Kaneko Yutaka Tamaura 《Journal of the American Ceramic Society》2000,83(10):2509-2514
Oxygen uptake and release of (Li,Mn) ferrite [LMF; (Li0.60 Mn1.20 Fe1.20 )1−δ O4 ; δ= 0.007 to 0.033] was investigated concerning the relations between redox reactions of ferrite and cation migration. Mössbauer spectroscopy and X-ray diffractometry showed that some of the Li+ and Fe3+ ions migrated from the A sites to the B sites of the spinel-type structure and Mn4+ ions migrated from the B sites to the A sites during oxygen uptake at 573 K. The cation-deficient LMF formed by the oxygen uptake released oxygen molecules in He gas only at 660 K. The cation migration during the oxygen release was in the opposite direction of the movement during oxygen uptake at 573 K. 相似文献
983.
Michio Takeda Akinori Saeki Jun-ichi Sakamoto Yoshikazu Imai Hiroshi Ichikawa 《Journal of the American Ceramic Society》2000,83(5):1063-1069
SiC-based fibers with various chemical compositions were synthesized using an irradiation-curing process. Polycarbosilane (PCS) fibers were cured by irradiation with an electron beam in a helium atmosphere. The cured PCS fibers were pyrolyzed at 1300°C under controlled hydrogen or argon atmospheres, and SiC fibers with C/Si of 0.84 to 1.56 were obtained. The fibers consisted of <1.0 wt% O, <0.2 wt% N, <0.1 wt% H, with the balance being Si and C. The mechanism of pyrolytic transformation of cured PCS to SiC-based ceramics was investigated using TG/DTA analysis. Greater mass losses were observed during pyrolysis in a hydrogen atmosphere than in argon. This result suggests that the hydrogen atmosphere suppresses H2 evolution and helps to remove excess carbon as CH4 during pyrolysis. The microstructure and mechanical properties of the resulting SiC-based fibers were found to be very dependent on their C/Si chemical compositions. 相似文献
984.
Zdzislaw Czarnul Tetsuro Itakura Noriaki Dobashi Takashi Ueno Tetsuya Iida Hiroshi Tanimoto 《Analog Integrated Circuits and Signal Processing》2000,25(3):189-207
The system architectures, which allow a high performance fully balanced (FB) system based on ordinary/modified single-ended opamps to be implemented, are investigated and the basic and general requirements are formulated. Two new methods of an FB analog system design, which contribute towards achieving both a high performance IC system implementation and a great reduction of the design time are presented. It is shown that a single-ended system based on any type of opamp (rail-to-rail, constant g
m
, etc.), realized in any technology (CMOS, bipolar, BiCMOS, GaAs), can be easily and effectively converted to its FB counterpart in a very practical way. Using the proposed rules, any FB system implementation with opamps (data converter, modulator, filter, etc.) requires only a single-ended system version design and the drawbacks related to a conventional FB system design are avoided. The principles of the design are pointed out and they are verified by experimental results. 相似文献
985.
Yi Liu Toyoki Fujiwara Hiroshi Yukawa Masahiko Morinaga 《Solar Energy Materials & Solar Cells》2000,62(1-2)
Employing the DV-Xα molecular orbital method, lithium intercalation effect and alloying effect have been investigated on the electronic structures of spinel MxMn2−xO4 and LiMxMn2−xO4 (M=Ti, V, Cr, Mn, Fe, Co, Ni and Cu). It is found that the lithium intercalation induces the electron transfer from Li to the surrounding O ions, and enlarges the Mn-3d/O-2p band gap greatly. Such a modification of the oxygen electronic state is probably related to the electrochemical cell voltage. This lithium intercalation effect still holds even in the alloyed systems. However, the amount of transferred charges from M to O ions changes depending on the alloying element, M. So the alloying addition modifies the oxygen electronic state and influences the lithium intercalation process indirectly. 相似文献
986.
Motohiko Ii Hiroshi Eda Takaichi Imai Masaya Nishimura Takahiko Kawasaki Jun Shimizu Takeyuki Yamamoto Libo Zhou 《Precision Engineering》2000,24(3):231
Using water-insoluble cutting fluids, which are good in lubricity but easy to mist, always risks firing and environmental problems. On the other hand, the current water-soluble coolants fail to deliver sufficient lubricity to heavy cutting applications. This study has newly proposed and developed a high water-content cutting fluid, based upon a new concept of having high lubricity despite of its water-soluble nature. As compared to the commercialized water-insoluble cutting fluid, the new cutting fluids shows a better capability of preventing oil mist and is fully applicable into cutting of various metallic materials, particularly effective in cutting of S45C and SUS304. The study also reveals a fact that a sulfur-type extreme pressure agent is the key element to enhance the cutting performance at high temperature. 相似文献
987.
988.
Yoshinori Horii Mitsuhiro Ikawa Koichi Sakaguchi Masayuki Chikamatsu Yuji Yoshida Reiko Azumi Hiroshi Mogi Masahiko Kitagawa Hisatoshi Konishi Kiyoshi Yase 《Thin solid films》2009,518(2):642-3524
We have investigated self-assembled monolayer (SAM) treatment on SiO2 gate insulator of poly(3-hexylthiophene) (P3HT) thin-film transistor (TFT), and demonstrated a correlation between mobility and surface free energy of the insulator. The device with lower surface free energy shows higher mobility. The docosyltrichlorosilane (DCTS)-treated device exhibits the best performance among the various SAM-treated devices examined. Field-effect mobility, on/off ratio and threshold voltage of the DCTS-treated P3HT TFT were 0.015 cm2/Vs, >105 and −14 V, respectively. 相似文献
989.
Hitoshi Morioka Keisuke Saito Shintaro Yokoyama Takahiro Oikawa Toshiyuki Kurosawa Hiroshi Funakubo 《Journal of Materials Science》2009,44(19):5318-5324
Epitaxial Pb(Zr0.35Ti0.65)O3 (PZT) thin films with tetragonal symmetry and thicknesses ranging from 45 to 230 nm were grown at 540 °C on SrRuO3-coated (001)SrTiO3 substrates by pulse-injected metalorganic chemical vapor deposition. The effect of the film thickness on the ferroelectric
domain structure and the dielectric and ferroelectric properties were systematically investigated. Domain structure analysis
of epitaxial PZT films was accomplished with high-resolution X-ray diffraction reciprocal space mapping and high-resolution
transmission electron microscopy. Fully polar-axis (c-axis)-oriented epitaxial PZT thin films with high ferroelectric polarization values [e.g., remanent polarization (P
r) ~ 90 μC/cm2] were observed for film thicknesses below 70 nm. Films thicker than 70 nm had a c/a/c/a polydomain structure and the relative volume fraction of c-domains monotonously decreased to about 72% on increasing the film thickness up to 230 nm , and finally P
r diminished to about 64 μC/cm2 for the 230-nm-thick epitaxial film. These polarization values were in good agreement with the estimated values taking into
account the volume fraction of the c-axis-oriented domains while assuming a negligible contribution of 90° domain reorientation caused by an externally applied
electric field. 相似文献
990.
Hiroshi Chiba Tetsuro Ogushi Hideo Nakajima Shunkichi Ueno Kahoru Torii Toshio Tomimura 《Advanced Engineering Materials》2009,11(10):848-851
Lotus‐type porous metals with many straight pores are attractive for use as heat‐sinks because a large heat‐transfer capacity can be obtained, due to the small diameter of the pores. In order to use lotus‐type porous copper effectively as a heat sink, it is important to know the effective thermal conductivity considering the effect of pores on heat conduction in the material. Since these metals have anisotropic pores, a steady‐state comparative longitudinal heat‐flow method for measuring thermal conductivity, referring to an ASTM standard, is better than other methods. So far, the effective thermal conductivity of lotus‐type porous copper has been measured by using specimens of different thickness (the SCHF‐DT method). In this paper, the uncertainty in the effective thermal conductivity of a specimen measured using this method was evaluated by comparison between numerical analysis and current experimental data. The following conclusions were drawn: 1) The uncertainty showed good agreement with the uncertainty analysis; 2) The contribution of the thermal grease thickness was large, based on a combined standard uncertainty analysis; and, 3) The effective thermal conductivity perpendicular to the pores of lotus copper can be measured within 10% uncertainty by this method. 相似文献