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151.
From the temperature dependence of the hole concentration in unirradiated lightly Al-doped 4H-SiC epilayers, an Al acceptor with EV + 0.2 eV, which is an Al atom (AlSi) at a Si sublattice site, and an unknown deep acceptor with EV + 0.35 eV are found, where EV is the top of the valence band. Both the densities are similar. With irradiation of 0.2 MeV electrons the Al acceptor density is reduced, while the unknown deep acceptor density is increased. Judging from the minimum electron energy required to displace a substitutional C atom (Cs) or the AlSi, the bond between the AlSi and its nearest neighbor Cs is broken due to the displacement of the Cs by this irradiation. Moreover, the displacement of the Cs results in the creation of a complex (AlSi-VC) of AlSi and a carbon vacancy (VC), indicating that the possible origin of the deep acceptor with EV + 0.35 eV is AlSi-VC. 相似文献
152.
Takeshi Naito Hideo Ueda Masao Kikuchi 《Metallurgical and Materials Transactions A》1984,15(7):1431-1436
The characteristic fatigue behavior of carburized and quenched steel with internal oxides and non-martensitic microstructure near the surface was presented through rotating bending fatigue test. The S-N diagram revealed two knees and the specimens continued to fail over 107 stress cycles. The fatigue limit could not be obtained even at 108 stress cycles. The test results were compared to those for the specimens without surface structure anomalies to show the effect of structure anomalies on the fatigue behavior of carburized steel. 相似文献
153.
Masahiro Sugaya Masakazu Takeshi Tomoji Yamashiki Toshio Oikawa Kan-Ichi Fujii 《Electromagnetic Compatibility, IEEE Transactions on》1982,(1):20-25
Correlation of light emission, discharge structure, waveform of the discharge current, electrode configuration, and electromagnetic radiation is examined with the intent of obtaining an effective means for preventing electromagnetic interference (EMI) due to a short-gap discharge. The electromagnetic radiation (EMR) level resulting from a current step which, in turn, was formed by a discrete movement of a cathode spot was clearly recognized. A combination of needle rotor and needle post gave the smallest electromagnetic radiation level in the experiments. 相似文献
154.
Takeshi Kuroki Takashi Sawaguchi Kazumasa Suzuki Shoaki Ide Tadashi Ikemura 《Polymer》1983,24(4):428-432
The distribution of double bonds in thermally degraded polyisobutylene was determined quantitatively by using pulsed Fourier transform 1H n.m.r. spectroscopic analysis. The double bonds in the degraded polymer did not exist in the interior but at the terminal positions of the polymer chain. These olefins were of the terminal trisubstituted and terminal vinylidene types. The content of the former was much greater than that of the latter. This shows that radical chain transfer predominantly occurs at the methylene hydrogen rather than at the methyl groups of the polymer chain. The average number of double bonds per molecule, f, was greater than 1 and tended to be near 2. Thereby most of the degraded polyisobutylene was shown to have two terminal unsaturations per molecule. 相似文献
155.
This paper presents a finite strip analysis of curved composite girders with incomplete interaction. In the present analysis curved composite girder bridges are modelled by curved strip elements for the concrete slab and steel girder and spring elements for the shear connectors. The shear connectors are assumed as a two-dimensional spring element along the nodal line. The proposed method is applied to the analysis of curved box girders, curved plates and curved composite girder bridges with complete and incomplete interaction. Some analytical results obtained by this method are compared with the test results and theoretical values obtained by other methods, and they are in good agreement. Slip behavior of curved composite box girders is also discussed based on the results by the proposed method. 相似文献
156.
157.
The relationship between ductility and material parameters such as grain-boundary (GB) precipitate size and dimple size in an Al-6.0% Zn-2.6% Mg alloy has been studied. Under the condition of a given GB precipitate size, the ductility increases with decreasing number of GB precipitates and dimples per unit area. The critical GB precipitate sizes acting as the nuclei for void formation are deduced. 相似文献
158.
Certain non-crystalline germanium films (> 10 μm in thickness) prepared by rf-sputtering crystallize “explosively” at room temperature when initiated by pricking the surface with a sharp point (or certain other methods). The propagation velocity of the crystallization at room temperature was found to be as fast a 1200 mm sec?1 depending somewhat on the conditions of film preparation, thickness, etc. The density of several such crystallizable films was determined as 5.05 g cm?3±1%. The crystallite size in the crystallized films, measured by X-ray broadening, was typically larger than 500 Å. A model for the crystallization process invokes a cascade energy transfer process, basically thermal in nature. 相似文献
159.
Takahashi H Masuda K Ando T Kobayashi T Honda H 《Journal of Bioscience and Bioengineering》2004,98(3):193-199
Gene expression profiling data from DNA microarray were analyzed using the fuzzy neural network (FNN) modeling method for predicting the distant metastases of breast cancer. The best model consisting of five genes was able to predict metastases of breast cancer with 94% accuracy. Furthermore, 100% accuracy was achieved by majoritarian decision using only 25 genes from five noninferior models which were constructed independently. From the constructed model, gene expression rules, which may cause distant metastases, were explicitly extracted and 60% of the metastases cases could be explained by this rule. The FNN modeling method described in this paper enables precise extraction of significant biological markers affecting prognosis without prior knowledge. 相似文献
160.
Mikito?MamiyaEmail author Takashi?Tsurue Hiroyuki?Miyazaki Takeshi?Okutani 《Microgravity science and technology》2004,15(2):13-17
The solidification process and structures of CdTe solidified in microgravity were studied using the unidirectional cooling
apparatus in a 10 m drop tower. Since the drop tower provides 1.4 seconds of microgravity, the unidirectional cooling apparatus
cools samples rapidly by cooling gas. The system adopts a Pt heater, which accurately heats samples to a maximum of 1300°C.
The sample is placed in an ampoule under vacuum conditions. A flat wall in the ampoule divides the inner sealed sample from
the outer open side. A nozzle blowing cooling gas is directed on to the outer wall, and cools the sample until solidification.
The cooling properties were measured during CdTe solidification in microgravity. The result shows that solidification occurred
between 0.9 and 1.3 seconds after release, so solidification is completed in microgravity. Optical microscope (OM) observation
of the sample solidified in microgravity revealed that it produces CdTe and Te phases with segregation patterns, and the structures
are ordered along the cooling direction, whereas no order is observed in the structures of the terrestrial sample solidified
under 1 g. 相似文献