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131.
Ha Yong Lee Se Hun Jung Soo Yong Lee Young Ho You Kyung Hyun Ko 《Applied Surface Science》2005,252(5):1891-1898
Al-Al2O3 composite coatings with different Al2O3 particle shapes were prepared on Si and Al substrate by cold spray. The powder compositions of metal (Al) and ceramic (Al2O3) having different sizes and agglomerations were varied into ratios of 10:1 wt% and 1:1 wt%. Al2O3 particles were successfully incorporated into the soft metal matrix of Al. It was found that crater formation between the coatings and substrate, which is typical characteristic signature of cold spray could be affected by initial starting Al2O3 particles. In addition, when the large hard particles of fused Al2O3 were employed, the deep and big craters were generated at the interface between coatings and hard substrates. In the case of pure soft metal coating such as Al on hard substrate, it is very hard to get proper adhesion due to lack of crater formation. Therefore, the composite coating would have certain advantages. 相似文献
132.
133.
本文主要探讨在高等数学教学中培养学生技能技巧的最佳教学方式的选优问题,并由此给出了正交试验设计在教学改革中的一个应用实例. 相似文献
134.
135.
热敏电阻温度计的设计与制作 总被引:2,自引:0,他引:2
本文介绍了设计性实验“热敏电阻的设计与制作”的实施情况。说明了只要选题合适、要求恰当,设计性实验不仅可行,而且对物理实验训练的总结提高十分有效。 相似文献
136.
137.
Conventional design of radiation detectors uses sintered ceramic insulating modules. The major drawback of these ceramic components
is their inherent brittleness. Ion chambers, in which these ceramic spacers are replaced by metallic components with plasma
spray coated alumina, have been developed in our Research Centre. These components act as thin spacers that have good mechanical
strength as well as high electrical insulation and replace alumina insulators with the same dimensions. As a result, the design
of the beam loss monitor ion chamber for CAT could be simplified by coating the outer surface of the HT electrode with alumina.
One of the chambers developed for isotope calibrator for brachytherapy gamma sources has its outer aluminium electrode (60
mm dia × 220 mm long) coated with 250 μ thick alumina (97%) + titania (3%).
In view of potential applications in neutron-sensitive ion chambers used in reactor control instrumentation, studies were
carried out on alumina 100 μ to 500 μ thick coatings on copper, aluminium and SS components. The electrical insulation varied
from 108 ohms to 1012 ohms for coating thicknesses above 200 μ. The porosity in the coating resulted in some fall in electrical insulation due
to moisture absorption. An improvement could be achieved by providing the ceramic surface with moisture-repellent silicone
oil coating. Irradiation at Apsara reactor core location showed that the coating on aluminium was found to be unaffected after
exposure to 1017 nvt fluence. 相似文献
138.
Peter Heering 《Physics in Perspective (PIP)》2006,8(1):52-63
I discuss our replication of the wire-torsion experiments that Charles Augustin Coulomb (1736–1806) reported in a session
of the Paris Académie des Sciences in 1784. I first explain the nature and purpose of the replication method and then apply it to an analysis of Coulomb’s experiments.
I conclude by placing Coulomb’s presentation of his memoir into its specific historical contest. 相似文献
139.
Matthieu Lecompte Christophe Dumouchel 《Particle & Particle Systems Characterization》2008,25(2):154-167
The three‐parameter, Generalized Gamma function solution of a recent MEF formulation used to derive liquid spray drop‐size distribution, is applied to sprays resulting from three different atomization processes. The objectives of these applications are to determine the sign of the parameters for which this function reports a more reliable fit and to further understand the parameter stability problem reported elsewhere. It is found that the lack of stability of the parameters is related to a characteristic feature of the mathematical function and appears for a series of spray drop‐size distributions with constant shape. For each situation analyzed in the present study, the Generalized Gamma function provides a very good fit with parameters that are either constant or correlated to the working conditions. As far as the sign of the parameters is concerned, the results show that the best formulation is a function of the spray and that it is impossible to know, a priori, which parameter sign will report the best fit. Finally, for one situation, it is found that the Generalized Gamma function allows extrapolation of drop sizes outside the measured values. All of the results converge to conclude that the three‐parameter Generalized Gamma function, which is identical to the well‐known Nukiyama‐Tanasawa distribution, accumulates valuable attributes to represent liquid spray drop‐size distributions. 相似文献
140.
本文采用有限容积法对制冷剂喷射冷却(Cryogen spray cooling,CSC)过程进行了数值分析,研究了皮肤组织温度场随时间、空间的分布规律,初步分析了喷射过程中可能发生的冷损伤.探讨了不同喷嘴距离对于喷射换热过程的影响.结果表明:本文的模拟结果定性符合文献中的试验结果;由于制冷剂喷射不均匀性带来的冷保护不足问题可以通过适当延长冷却时间(如大于80 ms)加以避免;低温制冷剂带来的冷损伤仅局限于浅表皮层,不会对人体造成伤害;喷射距离对于整个换热过程的影响非常有限,可以较为自由地布置喷嘴位置. 相似文献