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排序方式: 共有10000条查询结果,搜索用时 328 毫秒
991.
992.
993.
本文利用脉冲直流反应磁控溅射的方法制备了五氧化二钽 (Ta2 O5)薄膜 ,俄歇电子能谱仪测试了薄膜的成分含量 ,椭偏仪测试了Ta2 O5薄膜的厚度和折射率 ,XRD分析了薄膜的晶体结构 ,并且分别研究了氧气含量、基底温度等成膜工艺对薄膜的影响。研究结果表明薄膜的成分主要是由氧气含量决定的。利用金属 绝缘体 (介质膜 ) 金属 (MIM)结构初步对Ta2 O5薄膜进行了电学性能的测试 :皮安电流电压源测试了薄膜的I U特性 ,制备出的薄膜折射率在 2 1~ 2 2 ,MIM的I U特性曲线显示了较好的对称性和低的漏电流密度 相似文献
995.
Effect of magnesium content on the ageing behaviour of water-chilled Al-Si-Cu-Mg-Fe-Mn (380) alloy castings 总被引:1,自引:0,他引:1
A study of the effect of magnesium concentration on the ageing behaviour as measured by the hardness of 380 alloy was conducted
for three levels of magnesium, namely 0.06 (base alloy), 0.33 and 0.5 wt%, for water-chilled castings (dendrite arm spacing
∼ 10–15 μm). Differential scanning calorimetry analysis of as-cast samples was carried out to determine the changes in the
reactions of the phases obtained during alloy solidification, employing heating rates of 0.1 and 1.0°Cs−1, up to approximately 700°C. Two heat treatments were applied to the as-cast alloys: T5 comprising ageing at 25 (room temperature),
155, 180, 200 and 220°C, for times up to 200 h, and T6 comprising solution heat treatment at 480 °C or 515°C for 8 h, followed
by quenching in warm water at 60°C, followed by immediate artificial ageing at 155 or 180°C for varying times up to 100h.
The results show that the higher hardness values obtained with T6 treatment can be explained by the excess precipitation of
magnesium-containing phases in the as-solidified alloys. This precipitation could be eliminated under the high cooling-rate
conditions prevalent in die-casting operations so that T5 treatment may be used to replace T6 treatment to produce the same
hardness values. In addition, solution heat treatment in the low-temperature range (480–515°C) is adequate to produce the
required changes in silicon morphology and dissolution of magnesium in the matrix. No significant difference in hardness behaviour
was observed when the magnesium content was increased beyond 0.3 wt%. 相似文献
996.
可编程光学二值双轨逻辑门 总被引:1,自引:0,他引:1
基于双轨逻辑,本文提出一种可级联的并行二值逻辑门。所有十六种二值逻辑运算可以采用偏振半波相延编程来实现。也提出了用电光晶体实现实时编程的方法。本文中给出了实验结果。 相似文献
997.
P. K. Chaviaropoulos I. G. Nikolaou K. A. Aggelis N. N. Soerensen J. Johansen M. O. L. Hansen Mac Gaunaa T. Hambraus Heiko Frhr. von Geyr Ch. Hirsch Kang Shun S. G. Voutsinas G. Tzabiras Y. Perivolaris S. Z. Dyrmose 《风能》2003,6(4):365-385
Aerodynamic modelling of HAWT rotors by means of “engineering methods” has reached a saddle point, where no further development can be expected without a breakthrough in understanding the physics of unsteady, rotating three‐dimensional flows. However, such a breakthrough becomes ever more necessary, as the size of the wind turbines increases. With the experimental work in that direction being mostly limited to observing the phenomena and interpreting the associated mechanisms, and its increased cost, alternatives are being sought. The use of CFD techniques and state‐of‐the‐art Navier–Stokes solvers is considered a very serious contender, a belief shared by the members of the present consortium, which has worked on the VISCEL JOR3‐CT98‐0208 Joule III project. This project's goal was to determine the aerodynamic characteristics as well as the aeroelastic behaviour of wind turbine blades across their broad range of operational conditions, from attached to highly separated flow regimes. The work programme included specific tasks for the validation and assessment of existing 3D solvers, for the parametric study of 3D flow around realistic blades and for the investigation of aeroelastic stability, at the blade section level. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
998.
999.
This paper deals with fault detection problems in sampled-data (SD) systems. A tool is first introduced for the analysis of intersample behavior of SD systems in the frequency domain from the viewpoint of fault detection and isolation. Based on it, a direct design approach of fault detection systems for SD systems is proposed, and further the problem of full decoupling from unknown disturbances is studied. 相似文献
1000.
Student O. Z. Rusyn B. P. Kysil' B. V. Kobasyar M. I. Stakhiv T. P. Markov A. D. 《Materials Science》2003,39(1):17-24
We give a quantitative estimate of changes in the structure of 15Kh2MFA steel after its long-term exposure to the combined action of high temperature, tensile stresses, and hydrogen as the factors of degradation of this steel under conditions of oil hydrocracking. Under laboratory conditions, we study the effect of high-temperature hydrogen degradation of 15Kh2MFA heat-resistant steel on changes in the quantitative characteristics of its structural elements, in particular, in the dimension and average distance between carbides as well as in their orientation from one grain to another. Algorithms for the solution of the formulated problems are described, and the possibilities of proposed approaches for the quantitative automatic processing of metallographic images are shown. 相似文献