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排序方式: 共有1068条查询结果,搜索用时 15 毫秒
991.
Ryuhei Kimura Tokio Nakada Paul Fons Akimasa Yamada Shigeru Niki Takeo Matsuzawa Kiyoshi Takahashi Akio Kunioka 《Solar Energy Materials & Solar Cells》2001,67(1-4)
CuInSe2 and CuIn3Se5 thin films have been deposited using sodium compounds such as Na2Se and Na2S onto Corning 7059 glass substrates by the two-stage co-evaporation method. Enhanced grain growth and preferred (1 1 2) grain orientation as well as a decrease in resistivity with respect to undoped films were observed with sodium incorporation. A clear correlation between the photoluminescence spectra and the resistivity of the films was found by comparing the properties of films with and without Na incorporation. These observations suggest that compensation is reduced due to the suppression of donor-type defects by the presence of Na. 相似文献
992.
Polycarbonate was decomposed into phenol, bisphenol A and p-isopropenylphenol by the reaction at 130–300 °C in water. The decomposition reaction was accelerated by the addition of Na2CO3, and the yield of identified products reached 68% in the reaction at 250 °C for 1 h. By using the decomposed products, the
prepolymer of phenol resin was synthesized. 相似文献
993.
Akio Hirose Nobutaka Kurosawa Kojiro F. Kobayashi Hirotaka Todaka Hiroto Yamaoka 《Metallurgical and Materials Transactions A》1999,30(8):2115-2120
In welding 6061-T6 aluminum alloy, softening caused by the dissolution of strengthening β″ (Mg2Si) precipitates occurs in heat-affected zones (HAZs). Laser beam welding is advantageous in view of narrower softened regions.
The width of the softened region in a laser beam weld with a welding speed of 133 mm/s is 1/7 that of a tungsten inert gas
(TIG) weld with a speed of 5 mm/s. The hardness distributions and width of softened regions in the HAZ have been quantitatively
predicted to characterize the laser beam welding process. To this end, a kinetic equation describing the dissolution of age
precipitates has been established and has been applied to 6061-T6 aluminum weldments. The hardness profiles and the width
of softened zones have been successfully predicted in both welding processes. Prediction of the width of softened regions
with varying power inputs and welding speeds reveals that a high energy density and a high welding speed in laser beam welding
result in significantly narrower softened regions, in which the width is insensitive to variations in welding parameters compared
to that of TIG welding. 相似文献
994.
Michiya Matsusaki Akio Kishida Neil Stainton Christopher W. G. Ansell Mitsuru Akashi 《应用聚合物科学杂志》2001,82(10):2357-2364
D,L -Lactic acid (DLLA) was polycondensed with 4-hydroxycinnamic acid (4HCA), a derivative of cinnamic acid, to prepare a novel functional biodegradable polymer. The polymer was prepared using two different methods, the solvent method, which used acetic anhydride as the solvent, and the direct method. White and brown-colored copolymers were obtained by these two methods, respectively. 1H-NMR spectroscopy and UV-visible spectroscopy revealed that the double bond of 4HCA was almost completely destroyed when the copolymer was prepared by the direct method. On the other hand, copolymers in which the double bond was preserved in the 4HCA–DLLA copolymer were successfully obtained using the solvent method. The solubility of the copolymers obtained by the solvent method in organic solvent was poor. When the copolymer was prepared under a 4HCA:DLLA ratio of 20:80 using the solvent method, the resulting copolymer had high solubility in organic solvents and the double bond was preserved. Moreover, it was confirmed that the 4HCA–DLLA copolymer synthesized by the solvent method was both photoreactive and biodegradable. The 4HCA–DLLA copolymer is expected to be used as basic material for tissue engineering and drug delivery systems, in addition to applications as an orthopedic matrix and a degradable plastic. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2357–2364, 2001 相似文献
995.
The crystallographic orientation dependence of surface morphology of indentation creep on a nickel-based single crystal superalloy is investigated by using crystal plasticity slip theory with a three-dimensional (3D) finite element model. The numerical results show that the pile-up patterns developed around the indentation imprint exhibit four-, two-, and threefold symmetry on the surfaces of [0 0 1]-, [0 1 1]-, and [1 1 1]-oriented single crystals, respectively. The evolution of radial and hoop stresses around the crater provides important information for possible radial crack nucleation, whose critical locations depend on crystallographic orientations. These characteristics can be well explained in the viewpoint of crystallographic anisotropy. The findings may shed some light on understanding of the crystal structures and its time-dependent deformation mechanisms with the indentation method. 相似文献
996.
Recent studies on electron emission from diamond and related materials are reviewed. The properties of the diamond surface have been carefully investigated with well-defined treatments and it has been confirmed that the hydrogenated diamond surface has a negative electron affinity (NEA). The field electron emission properties of a variety of carbon materials were investigated and remarkable results of high emissivity at low fields were documented. The mechanism for the low field emission was partly attributed to an NEA nature although the emission surface was not always confirmed to have NEA properties. Electron emission devices with NEA diamond surfaces have been developed. An emission device of metal-insulator-semiconductor structure was designed and built and its performance was investigated. 相似文献
997.
Kohji Narui Keiichi Furuta Hirohide Yata Akio Nishida Yasuhiko Kohtoku Tokuo Matsuzaki 《Catalysis Today》1998,45(1-4):173-178
Catalytic activity of ZrO2 supported PdO catalysts for methane combustion has been investigated in comparison with Al2O3 supported PdO catalysts. It was found that the drop of catalytic activity owing to decomposition of PdO at a high temperature region (600–900°C) was suppressed by using ZrO2 support. Temperature-programmed reduction (TPR) measurements of the catalyst with hydrogen revealed that the PdO of PdO/Al2O3 catalyst was reduced at the temperature less than 100°C, whereas in PdO/ZrO2 catalyst the consumption of hydrogen was also observed at 200–300°C. This result indicates that the stable PdO species were present in the PdO/ZrO2 catalyst. In order to confirm the formation of the solid solution of PdO and ZrO2, X-ray diffraction (XRD) analyses of the mixtures of ZrO2 and PdO calcined at 700–900°C in air were carried out. The lattice volume of ZrO2 in the mixture was larger than that of ZrO2. Furthermore, the Pd thin film on ZrO2 substrate was prepared as a model catalyst and the depth profile of the elements in the Pd thin film was measured by Auger electron spectroscopy (AES). It was confirmed that Zr and O as well as Pd were present in the Pd thin film heated at 900°C in air. It was considered that the PdO on ZrO2 support might be stabilized by the formation of the solid solution of PdO and ZrO2. 相似文献
998.
A method is described for automatic release of a levitated object without external control commands in levitation systems (such as magnetic and electrostatic levitation). The key aspect is an integral action in the controller. Examples of a zero-power controller for magnetic levitation and a proportional-integral-derivative (PID) controller for electrostatic levitation are presented. Automatic release of the levitated object is a consequence of the controller behavior when the levitated object has a temporary forced position error. In a pick and place task that uses non-contact levitation techniques, a position error is induced at placing. Automatic release simplifies the task of placing, as no external command is required. The principle of this release method is explained and analyzed using a zero-power controller in a magnetic levitation system. For electrostatic levitation, which is analogous to magnetic levitation, experimental results of an automatic release based on PID-control are presented. A general guideline is derived to tune the controller settings so as to achieve automatic release, and this is supported by experiments. 相似文献
999.
Analysis of coumarin and its glycosidically bound precursor in Japanese green tea having sweet-herbaceous odour 总被引:2,自引:0,他引:2
Ziyin Yang Tomomi Kinoshita Aya Tanida Hironori Sayama Akio Morita Naoharu Watanabe 《Food chemistry》2009
Coumarin is a natural product well-known for its pleasant sweet-herbaceous and cherry flower-like odour. Despite coumarin being widely found in the plant kingdom, its occurrence in tea leaves is very poorly characterised. In this work, green tea made from the cultivars “Shizu-7132”, “Koushun” and “Tsuyuhikari” were found to have sweet-herbaceous odour. Application of the stable isotope dilution assay for the quantification of coumarin revealed that its levels in these Japanese green tea products ranged from 0.26 to 0.88 μg/g of green tea product, whereas concentrations were generally below 0.2 μg/g in common green tea products. In contrast to the leaf, the stem part contained much less coumarin. During the manufacturing process of the tea (Shizu-7132), the steaming time and drying temperature influenced the content of coumarin in the final product. Due to hydrolysis of glycosidically bound coumarin precursors, in fresh tea leaves most coumarin occurred in its free form. Tea leaves also contained small amounts of bound coumarin precursors, such as primeveroside. 相似文献
1000.
A solar cooling project for hot and humid climates 总被引:1,自引:0,他引:1
This paper presents a solar house built in a southern city of China where the summer is long, hot and humid. The house was designed appropriately for the climate and was constructed with local building materials where possible. A multifunctional solar system was used and a method for indoor ventilation was proposed. The design included double walls and a triple roof in order to remove heat by ventilation of the building envelope. The external walls were clad with unglazed bricks to allow evaporative cooling. The house has been monitored since completion and more than one year of data is available. Analysis of the monitored data shows that the solar techniques proposed in this design are effective in a hot and humid climate. Effective ventilation strategies for the improvement of thermal comfort are also discussed. 相似文献