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排序方式: 共有853条查询结果,搜索用时 15 毫秒
141.
142.
Blue/DVD/CD compatible optical head 总被引:1,自引:0,他引:1
Compatibility with Digital Versatile Disc and Compact Disc has been demonstrated for two options of high-density optical disk systems using a blue laser diode. Option 1 (HD DVD) employs a 0.65 numerical aperture objective lens and a 0.6 mm thick protective layer disk, while Option 2 (Blu-ray Disc) employs a 0.85 numerical aperture objective lens and a 0.1 mm thick protective layer disk. An optical head has three laser diodes whose wavelengths are 405 nm, 660 nm, and 785 nm. A spherical aberration caused by the difference in the protective layer thickness of the disk is corrected by an objective lens magnification change, while the numerical aperture of the objective lens is controlled by a wavelength-selective aperture. Experimental results have shown that Option 1 is more preferable, but Option 2 is also acceptable from the viewpoint of the compatibility. 相似文献
143.
Abstract: Phase‐shifting digital holographic interferometry is a new method to measure displacement distribution on the surface of an object. Usually holography has speckle noise, which leads to a large error in the analysis of displacement and strain distributions. We previously proposed windowed phase‐shifting digital holographic interferometry (windowed PSDHI). The use of this method leads to accurate displacement analysis, decreasing the effect of speckle patterns. However, noise reduction involves a defect, which renders the spatial resolution low. In this paper, by comparing the conventional noise reduction method using spatial averaging with the windowed PSDHI on spatial resolution, the effectiveness of noise reduction is discussed. 相似文献
144.
To investigate the effect of molecular structure on macroscopic flow behavior of polymeric liquid, attempts have been made to embed the microscopic information into the flow simulation. Constitutive equation based on the theory of polymer dynamics is ideal but the theory is still under development. The CONNFFESSIT approach (where microscopic simulation is embedded into calculation grid in macroscopic simulation) is another promising direction but the computational cost is not practical yet. In this study, we propose another simple method using parameter-based bridging where the parameters for phenomenological constitutive equations in macroscopic flow simulation are obtained from coarse-grained molecular simulation. As an example, we performed a simulation of injection molding and examined the effect of molecular weight on warpage of the molded product. We used the primitive chain network simulation to calculate linear viscoelasticity of linear monodispersed polystyrenes from molecular weight. The obtained linear viscoelasticity was converted into the relaxation spectrum and into the flow curve to be used in the macroscopic simulations. From the flow curve, the parameters of an inelastic non-Newtonian constitutive equation were obtained and used for the simulation of filling process. The relaxation spectrum was used to calculate residual stress from the flow profile in the filling process. From the residual stress and thermal shrinkage, warpage of the product was obtained. For the examined thin plate product, significant change in the warpage direction was demonstrated according to the molecular weight of the material. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
145.
Yuichi Terazawa Masashi Mikami Takashi Itoh Tsunehiro Takeuchi 《Journal of Electronic Materials》2012,41(6):1348-1353
By using first-principles cluster calculations, we identified that Ta or W substitution for V is useful for decreasing the lattice thermal conductivity of the Fe2VAl Heusler alloy without greatly affecting the electron transport properties. It was clearly confirmed that the Fe2(V1?x Ta x )Al0.95Si0.05 (x?=?0, 0.025, 0.05), Fe2(V0.9?x Ta x Ti0.1)Al (x?=?0, 0.10, 0.20), and Fe2(V0.9?2x W x Ti0.1+x )Al (x?=?0, 0.05, 0.10) alloys indeed possessed large Seebeck coefficient regardless of the amounts of substituted elements, while their lattice thermal conductivity was effectively reduced. As a result of partial substitution of Ta for V, we succeeded in increasing the magnitude of the dimensionless figure of merit of the Heusler phase up to 0.2, which is five times as large as the Ta-free compound. 相似文献
146.
Osaka T Kimura Y Otsubo Y Suwa Y Tsuneda S Isaka K 《Journal of Bioscience and Bioengineering》2012,114(4):429-434
The anoxic ammonium oxidation (anammox) process has been regarded as an attractive alternative process to treat wastewater containing high ammonium concentrations. By the implementation of anammox process at moderately low temperatures (<25°C), the anammox process will be applied to more various industrial wastewater treatments. In this study, we established enrichment cultures of anammox bacteria from freshwater sediments by using an up-flow column reactor equipped with porous polyester nonwoven fabric at moderately low temperatures. Their nitrogen conversion rates reached 0.07-0.26kg-N/m(3)/d. Phylogenetic analysis based on 16S rRNA gene from enrichment cultures revealed the presence of various anammox bacteria affiliated with unknown anammox bacteria as well as known anammox candidates, i.e., Candidatus Kuenenia stuttgartiensis and Candidatus Brocadia fulgida, Candidatus Scalindua wagneri. Anammox bacterial populations were influenced by enrichment conditions, i.e., seed sediments and temperature. 相似文献
147.
Shigeki Hirasawa Ryosuke Wakiya Yuichi Hashikawa Tsuyoshi Kawanami Katsuaki Shirai 《机械工程与自动化:英文版》2014,(10):763-769
Precise temperature control to decrease movements in positions due to thermal expansion of work pieces is required in the manufacturing processes to achieve nanometer-order accuracy. We analytically examined the effect of a method of minimizing movements in positions on a plate with varying generation of noise-heat. Control by monitoring temperature changes caused larger movements in positions than that without control because maximum change in temperature occurred at non-monitoring positions. The best method of minimizing movements in positions due to thermal expansion of a plate with varying generation of noise-heat was model predictive control by the monitoring movements and distributed temperature changes in the control heater according to the effects of the generation of noise-heat. The maximum movement in positions was 6 nm, which was 1/4 times of that without control. 相似文献
148.
Tadashi C Ozawa Katsutoshi Fukuda Yasuo Ebina Kosuke Kosuda Akira Sato Yuichi Michiue Keiji Kurashima Takayoshi Sasaki 《Science and Technology of Advanced Materials》2011,12(4)
La–Eu solid solution nanosheets La2/3−xEuxTa2O7 have been synthesized, and their photoluminescence properties have been investigated. La2/3−xEuxTa2O7 nanosheets were prepared from layered perovskite compounds Li2La2/3−xEuxTa2O7 as the precursors by soft chemical exfoliation reactions. Both the precursors and the exfoliated nanosheets exhibit a decrease in intralayer lattice parameters as the Eu contents increase. However, there is a discontinuity in this trend between the nominal Eu content ranges x≤ 0.3 and x ≥ 0.4. This discontinuity is attributed to the difference in degree of TaO6 octahedra tilting for the La- and Eu-rich phases. La2/3−xEuxTa2O7 nanosheets exhibit red emission, characteristic of the f–f transitions in Eu3+ photoactivators. The photoluminescence emission can be obtained from both host and direct photoactivator excitation. However, photoluminescence emission through host excitation is much more dominant than that through direct photoactivator excitation, and this behavior is consistent with that of all the other rare-earth photoactivated nanosheets reported previously. The absolute photoluminescence quantum efficiency of the La2/3−xEuxTa2O7 nanosheets increases as the experimentally determined Eu contents increase up to x=0.45 and decrease above it. This result is in good agreement with the optimum photoactivator concentration expected from the percolation theory. These solid solution La2/3−xEuxTa2O7 nanosheets are excellent models for validating the theory of optimum photoactivator concentration in the truly two-dimensional photoactivator matrix. 相似文献
149.
Ikuhara Y 《Journal of electron microscopy》2011,60(Z1):S173-S188
Grain boundaries and interfaces of crystals have peculiar electronic structures, caused by the disorder in periodicity, providing the functional properties, which cannot be observed in a perfect crystal. In the vicinity of the grain boundaries and interfaces, dopants or impurities are often segregated, and they play a crucial role in deciding the properties of a material. Spherical aberration (Cs)-corrected scanning transmission electron microscopy (STEM), allowing the formation of sub-angstrom-sized electron probes, can directly observe grain boundary-segregated dopants. On the other hand, ceramic materials are composed of light elements, and these light elements also play an important role in the properties of ceramic materials. Recently, annular bright-field (ABF)-STEM imaging has been proposed, which is now known to be a very powerful technique in producing images showing both light- and heavy-element columns simultaneously. In this review, the atomic structure determination of ceramic grain boundaries and direct observation of grain boundary-segregated dopants and light elements in ceramics were shown to combine with the theoretical calculations. Examples are demonstrated for well-defined grain boundaries in rare earth-doped Al(2)O(3) and ZnO ceramics, CeO(2) and SrTiO(3) grain boundary, lithium battery materials and metal hydride, which were characterized by Cs-corrected high-angle annular dark-field and ABF-STEM. It is concluded that the combination of STEM characterization and first-principles calculation is very useful in interpreting the structural information and in understanding the origin of the properties in various ceramics. 相似文献
150.
Takahito Osawa Yuichi HatsukawaPeter W.U. Appel Hideaki Matsue 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2011,269(8):717-720
The authors have established a method of determining mercury and gold in severely polluted environmental samples using prompt gamma-ray analysis (PGA) and instrumental neutron activation analysis (INAA). Since large amounts of mercury are constantly being released into the environment by small-scale gold mining in many developing countries, the mercury concentration in tailings and water has to be determined to mitigate environmental pollution. Cold-vapor atomic absorption analysis, the most pervasive method of mercury analysis, is not suitable because tailings and water around mining facilities have extremely high mercury concentrations. On the other hand, PGA can determine high mercury concentrations in polluted samples as it has an appropriate level of sensitivity. Moreover, gold concentrations can be determined sequentially by using INAA after PGA. In conclusion, the analytical procedure established in this work using PGA and INAA is the best way to evaluate the degree of pollution and the tailing resource value. This method will significantly contribute to mitigating problems in the global environment. 相似文献