共查询到20条相似文献,搜索用时 546 毫秒
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针对实验中9.5μm峰值响应波长的n型长波量子阱红外探测器设计运用二维金属小球(铜)阵列作光耦合结构.金属小球阵列均匀填充在绝缘的胶黏剂中,基于惠更斯原理研究二维金属小球阵列体系的光耦合和光吸收,结果表明对9.5μm响应波长的长波量子阱红外探测器,采用周期为3μm,半径为0.9μm左右的金属小球阵列可以获得最佳的光耦合.优化设计后的量子效率(66%)远高于45°磨角耦合的量子效率(38%),为实验运用金属小球阵列进行长波量子阱红外探测器的光耦合提供了基本的理论依据和详细的优化设计方案. 相似文献
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高中物理探究平抛物体的运动,大多采用使小球从一定高度释放沿轨道滚动后做平抛运动的装置进行相关实验.那么小球的滚动在多大程度上影响实验的结果,在什么条件下可以不考虑小球的滚动. 相似文献
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利用物理仿真实验室模拟了绳系小球系统在复合场中的运动,首先分别将小球从A,C点静止释放,获取了小球的速率与加速度大小随时间的变化关系图,分析原因,总结规律,随后通过不断改变小球静止释放的位置,观察小球的运动轨迹,得出小球做部分圆周运动的条件,最后计算出小球从直线到圆周运动的临界位置以及在该位置所损失的机械能. 相似文献
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对平抛法测重力加速度进行了改进,选取朗威Dislab数字实验系统中的声音传感器测量小球下落时间,再计算重力加速度,此方法操作方便,易于在中学物理实验教学中实施. 相似文献
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Ádám Révész László PéterPéter J. Szabó Péter SzommerImre Bakonyi 《Current Applied Physics》2012,12(1):109-114
Fully amorphous Ni-P layer electrodeposited onto a Cu plate was subjected to severe plastic deformation using surface mechanical attrition treatment in a high energy SPEX 8000 shaker mill. Two series of experiments using different milling conditions (series I: 20 6.35-mm balls; series II: 100 1.59-mm balls) were carried out to explore the mechanism of the process and to investigate the structure of the developed coatings. The evolution of the microstructure and mechanical properties of the Ni-P layer after the deformation process was studied by x-ray diffraction, scanning electronmicroscopy and hardness measurements. We demonstrate that the different mechanical treatments controllably influence the mechanical behavior of the Ni-P metallic glass coating. When the vial of the mill is loaded with larger balls, deformation-induced Ni3P compound particles form in the amorphous matrix resulting in a hard (HV = 17 GPa) but non-uniform coating. In the case of milling with many small balls, the increase in the surface hardness is considerably lower (7 GPa) as a consequence of reduced impact energy. 相似文献
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It is proposed that dark matter could consist of compressed collections of atoms (or metallic matter) encapsulated into, for example, 20 cm big pieces of a different phase. The idea is based on the assumption that there exists at least one other phase of the vacuum degenerate with the usual one. Apart from the degeneracy of the phases we only assume standard model physics. The other phase has a Higgs vacuum expectation value appreciably smaller than in the usual electroweak vacuum. The balls making up the dark matter are very difficult to observe directly, but inside dense stars may expand absorbing the star and causing huge explosions (gamma ray bursts). The ratio of dark matter to ordinary matter is expressed as a ratio of nuclear binding energies and predicted to be about 5. 相似文献
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Lijun Zhao Hua Yang Shuiming Li Lianxiang Yu Yuming Cui Xueping Zhao Shouhua Feng 《Journal of magnetism and magnetic materials》2006
Composites of α-Fe/Fe3O4 having dimensions in the range of 100–150 nm have been prepared by disproportion method. The structure and morphology are investigated by XRD and TEM. XRD shows that the metal has got the BCC structure. TEM shows balls of metallic iron about 100-nm-wide stuck to magnetite grains. Magnetic measurement shows that the sample aged for 3 h and calcined at 200 °C has the maximal saturation magnetization corresponding to the highest concentration of α-Fe in the final sample. 相似文献
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A non-destructive testing method for silicon nitride bearing balls based on ultrasonic resonance spectroscopy is proposed here. Through the theoretical study of their elastic vibrations, it is possible to characterize the balls using a vibration mode that is similar to surface wave propagation. The study of the influence of C-crack defects on the resonances of Rayleigh modes is presented here. These C-cracks are typically formed by impacts between balls during finishing or handling. They are frequently found on the surface of silicon nitride bearing balls and these C-cracks decrease the rolling contact fatigue life considerably. This kind of defect is difficult to detect because the C-shaped surface crack is very small and narrow (500 μm × 5 μm), and its depth does not exceed 50 μm. The proposed methodology can both excite spheroidal vibrations in the ceramic balls and detect such vibrations over a large frequency range. In particular, high frequency vibrations are considered because these are similar to the surface waves propagating in the cortical zone of the ceramic balls and consequently they can be used to detect C-crack defects. 相似文献
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Saburo Tanaka Yoshimi Hatsukade Shuichi Suzuki 《Journal of magnetism and magnetic materials》2009,321(7):880-883
High-Tc superconducting quantum interference device (SQUID) is an ultra-sensitive magnetic sensor. Since the performance of the SQUID is improved and stabilized, now it is ready for application. One strong candidate for application is a detection system of magnetic foreign matters in industrial products or beverages. There is a possibility that ultra-small metallic foreign matter has been accidentally mixed with industrial products such as lithium ion batteries. If this happens, the manufacturer of the product suffers a great loss recalling products. The outer dimension of metallic particles less than 100 μm cannot be detected by an X-ray imaging, which is commonly used for the inspection. Ionization of the material is also a big issue for beverages in the case of the X-ray imaging. Therefore a highly sensitive and safety detection system for small foreign matters is required. We developed detection systems based on high-Tc SQUID with a high-performance magnetic shield. We could successfully measure small iron particles of 100 μm on a belt conveyer and stainless steel balls of 300 μm in water. These detection levels were hard to be achieved by a conventional X-ray detection or other methods. 相似文献
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Surface mechanical attrition treatment (SMAT) improves mechanical properties of metallic materials through the formation of nanocrystallites at their surface layer. It also modifies the morphology and roughness of the work surface. Surface roughening by the SMAT has been reported previously in a smooth specimen, however in this study the starting point was a rough surface and a smoothening phenomenon is observed. In this paper, the mechanisms involved in the surface smoothening of AISI 316L stainless steel during the SMAT are elucidated. The SMAT was conducted on a specimen with a roughness of Ra = 3.98 μm for 0–20 min. The size of milling balls used in the SMAT was varied from 3.18 mm to 6.35 mm. The modification of subsurface microhardness, surface morphology, roughness and mass reduction of the specimen due to the SMAT were studied. The result shows the increasing microhardness of the surface and subsurface of the steel due to the SMAT. The impacts of milling balls deform the surface and produce a flat-like structure at this layer. Surface roughness decreases until its saturation is achieved in the SMAT. The mass reduction of the specimens is also detected and may indicate material removal or surface erosion by the SMAT. The size of milling ball is found to be the important feature determining the pattern of roughness evolution and material removal during the SMAT. From this study, two principal mechanisms in the evolution of surface morphology and roughness during the SMAT are proposed, i.e. indentation and surface erosion by the multiple impacts of milling balls. A comparative study with the results of the previous experiment indicates that the initial surface roughness has no influence in the work hardening by the SMAT but it does slightly on the saturated roughness value obtained by this treatment. 相似文献
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An infinite number of elastically colliding balls is considered in a classical, and then in a relativistic setting. Energy
and momentum are not necessarily conserved globally, even though each collision does separately conserve them. This result
holds in particular when the total mass of all the balls is finite, and even when the spatial extent and temporal duration
of the process are also finite. Further, the process is shown to be indeterministic: there is an arbitrary parameter in the
general solution that corresponds to the injection of an arbitrary amount of energy (classically), or energy-momentum (relativistically),
into the system at the point of accumulation of the locations of the balls. Specific examples are given that illustrate these
counter-intuitive results, including one in which all the balls move with the same velocity after every collision has taken
place. 相似文献
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Although ceramic balls are used more and more for bearings in the aerospace and space industries, defects in this type of ceramic material could be dangerous, particularly if such defects are located close to the surface. In this paper, we propose a non-destructive testing method for silicon nitride balls, based on ultrasonic resonance spectroscopy. Through the theoretical study of their elastic vibrations, it is possible to characterize the balls using a vibration mode that is similar to surface wave propagation. The proposed methodology can both excite spheroidal vibrations in the ceramic balls and detect such vibrations over a large frequency range. Studying their resonance spectrums allows the balls’ elastic parameters be characterized. Ours is an original method that can quickly estimate the velocity of surface waves using high frequency resonances, which permits surface and sub-surface areas to be tested specifically. Two applications are described in this paper. Both use velocity measurements to achieve their different goals, the first to differentiate between flawless balls from different manufacturing processes, and the second to detect small defects, such as cracks. Our method is rapid and permits the entire ceramic ball to be tested in an industrial context. 相似文献
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Keivan Aghababaei Samani 《Reports on Mathematical Physics》2003,52(3):373-379
In this article we introduce a simple physical model which realizes the algebra of orthofermions. The model is constructed from a cylinder which can be filled with some balls. The creation and annihilation operators of orthofermions are related to the creation and annihilation operators of balls in certain positions in the cylinder. Relationship between this model and topological symmetries in quantum mechanics is investigated. 相似文献