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排序方式: 共有1492条查询结果,搜索用时 15 毫秒
91.
92.
螺旋波激发等离子体源的原理和应用 总被引:2,自引:0,他引:2
介绍了一种低气压,高密度等离子体源-螺旋波激发等离子体源,讲述了它的结构位形,该离子源在实际中的应用以及目前研究状况。 相似文献
93.
Considering the diffusion reaction at solid interfaces, the ignition temperature of compounds fabricated by self-propagating high-temperature synthesis (SHS) is modelled with the help of size-dependent activation energy. As reactant size decreases, ignition temperature also decreases. This is because of increased contact areas between the reactants and the lowered diffusion barrier, both of which must be calculated specifically for reactants in nanoscale. The model predictions and experimental results are consistent for some metallic compounds. 相似文献
94.
Quinary Ti-Zr-Hf-Cu-Ni high-entropy metallic glass thin films were produced by magnetron sputter deposition. Nanoindentation tests indicate that the deposited film exhibits a relatively large hardness of 10.4±0.6 GPa and a high elastic modulus of 131±11 GPa under the strain rate of 0.5 s−1. Specifically, the strain rate sensitivity of hardness measured for the thin film is 0.05, the highest value reported for metallic glasses so far. Such high strain rate sensitivity of hardness is likely due to the high-entropy effect which stabilizes the amorphous structure with enhanced homogeneity. 相似文献
95.
ZHANG QingChao PANG ShuJie LI Yi & ZHANG Tao Key Laboratory of Aerospace Materials Performance School of Materials Science Engineering Beijing University of Aeronautics Astronautics Beijing China 《中国科学:物理学 力学 天文学(英文版)》2011,(9)
Bulk metallic glasses (BMGs) with large supercooled liquid region are promising materials for superplastic forming. In this paper, we demonstrate a microstructure-based strategy to pinpoint the composition with the largest supercooled liquid region in La 86 x Al 14 Cu x (x=16 at%-20 at%) metallic glass system. By monitoring the changes in crystallization behavior of the glassy alloys with composition to search for the alloys exhibiting eutectic crystallization, the glassy alloys with the largest supercooled... 相似文献
96.
A High-Power Reflector Impulse Antenna with Dual-Tem Source 总被引:1,自引:0,他引:1
Chen Guo An-xue Zhang Hui Wu Yan-sheng Jiang Wen-bing Wang 《International Journal of Infrared and Millimeter Waves》2008,29(9):832-838
There are different demands on radiation efficiency and direction pattern according to various ultra-wideband (UWB) antennas
and high power applications. To obtain more radiating gain on bore-sight of paraboloidal reflector and centralized radiating
direction, a novel feeding structure called dual-TEM source has been designed and applied in half-paraboloidal reflector impulse
radiating antenna (IRA) applications. Simulation results proved that this proposed half-paraboloidal reflector IRA with dual-TEM
source provided greater radiation performance on bore-sight as a result of the synthesized power in the aperture space of
paraboloid. Moreover, lots of simulation work and comparison have been done in different feeding models to summarize a relative
optimal feeding structure. 相似文献
97.
一种高品质中空金属光波导 总被引:3,自引:0,他引:3
讨论了高品质中空金属光波导的工作原理及其制作工艺,制备了以金和银作为波导材料的中空波导管,并对空芯以及充入不同透明液体的液芯波导的透光特性进行了测试,结果表明:与中空介质波导相比,中空金属波导具有光传输损耗低,透过率对波导弯曲与失调不甚敏感等优点;而液芯金属波导的透光效率与透明材料的折射系数无关。文中描述了在特定波段内“中空光纤”的原理,并报道了He-Ne和CO2激光在中空金壁波导传输的实验结果。 相似文献
98.
99.
Chunheng Liu Yueguang Lu Chunlei Du Xiangang Luo 《International Journal of Infrared and Millimeter Waves》2007,28(12):1115-1122
A aperture-coupled patch antenna is designed with parasitic elements connecting to the rectangle ring on the bottom of antenna
substrate through metal vias, which lead the current induced by patch radiator to the top surface of antenna substrate. Therefore,
the effective radiation is enhanced and higher gain is achieved. The bandwidth is broadened simultaneously due to the structure
of aperture-coupled patch antenna with parasitic elements. Compared to the conventional aperture-coupled patch antenna, the
antenna gain increases averagely 2 dB due to the novel structure. Compared to patch antenna of electromagnetic band-gap, the
dimensions of novel patch antenna greatly decreases, which can be used as element in the array antenna. Two kinds manufactured
antenna are both measured in an anechoic chamber. The good agreements between numerical simulation and experimental prototype
have been obtained. 相似文献
100.