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111.
Channeling describes the collimated motion of energetic charged particles along the lattice plane or axis in a crystal. The energetic particles are steered through the channels formed by strings of atomic constituents in the lattice. In the case of planar channeling, the motion of a charged particle between the atomic planes can be periodic or quasiperiodic, such as a simple oscillatory motion in the transverse direction. In practice, however, the periodic motion of the channeling particles can be accompanied by an irregular, chaotic behavior. In this paper, the Moliere potential, which is considered as a good analytical approximation for the interaction of channeling particles with the rows of atoms in the lattice, is used to simulate the channeling behavior of positively charged particles in a tungsten (100) crystal plane. By appropriate selection of channeling parameters, such as the projectile energy E(0) and incident angle psi(0), the transition of channeling particles from regular to chaotic motion is demonstrated. It is argued that the fine structures that appear in the angular scan channeling experiments are due to the particles' chaotic motion. 相似文献
112.
在软件测试技术的不断发展过程中,自动化测试技术作为软件测试技术的一个分支,被越来越多的使用在软件测试的各个阶段,大大节省了软件测试成本、提高了测试效率、缩短了软件开发周期。本文结合自动化测试理论与技术,基于现有的自动化测试技术、测试框架以及自动化测试工具进行了研究,提出了一种基于当前较成熟的软件测试自动化技术-关键字驱动的自动化测试技术而构建的自动化测试框架模型,并在此框架模型的基础上,设计实现了基于Selenium的自动化测试框架。 相似文献
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The paper presents a valuation model of futures options trading at exchanges with initial margin requirements and daily price limit, and this result gives an academic guidance to design trading rules at exchanges. Unlike the leading work of Black, certain trading rules are considered so as to be more fit for practical futures markets. The paper prices futures options with initial margin requirements and daily price limit by duplicating them with the help of the theory of backward stochastic differential equations (BSDEs, for short). Furthermore, an explicit expression of the price Of the call (or the put) futures option is given and also is shown to be the unique solution of the associated nonlinear partial differential equation. 相似文献
115.
A laser diode directly end-pumped, passively Q-switched Nd:YVO4/Cr:YAG laser is presented in this paper. With 600 mW incident pump laser, Q-switched 1064 nm laser with an average power of 138 mW, pulse width of 19.8 ns, repetition rate of 170.1 kHz and peak power of 40.96 W is obtained. When a KTP crystal was inserted into the cavity, Q-switched 532 nm laser with an average power of 56 mW, pulse width of 28.4 ns, repetition rate of 118.2 kHz and peak power of 16.7 W is obtained at last. 相似文献
116.
Measuring the power-law exponent of an atmospheric turbulence phase power spectrum with a Shack Hartmann wave-front sensor 总被引:3,自引:0,他引:3
For non-Kolmogorov turbulence we develop a differential angle-of-arrival fluctuation coefficient, which is the ratio between the transverse and longitudinal differential angle-of-arrival variances, and a slope structure-correlation coefficient, which is the ratio between the transverse and longitudinal differences of the slope correlation function and the slope structure function, to measure the power-law exponent of a phase power spectrum with a Shack-Hartmann wave-front sensor: The differential arrival-of-angle fluctuation coefficient and the slope structure-correlation coefficient are both related to power-law exponent beta and are independent of strength parameter rho(0) of the turbulence. We compare the methods developed and use them to evaluate beta in recently completed horizontal atmospheric experiments for 1000-m laser beam propagation. 相似文献
117.
本文在自旋电荷相统一的非费米液体前提下,同时考虑相一作用V及层间随着作用TJ,推导出非费米液体层间隧道的超导转变温度Tc的解析式,给出了临界耦合因子λTJc,λc与α关系式,并且数值计算了零温能隙随TJ及α的变化趋势。 相似文献
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119.
C. C. Ling Y. Y. Shan B. K. Panda S. Fleischer C. D. Beling S. Fung 《Applied Physics A: Materials Science & Processing》1995,60(6):545-549
Recent positron lifetime studies made on the Au/GaAs interface with an applied electric field returning a significant fraction of bulk implanted positrons to the interface have revealed the presence of microvoids( 1 nm diameter) at the interface. In this work an attempt has been made to study these microvoids by observing the Doppler broadening on the annihilation radiation coming from them. This is done both by observing theS-parameter as a function of applied bias and by applying the generalized least-squares method to the deconvolution of the annihilation radiation lineshape. The general conclusion is that the Doppler-broadened data are consistent with the majority of positrons trapping into microvoids, probably associated with grain boundaries. The data suggest that these open volume defects are more associated with the Au film rather than the Au-Ga alloyed interfacial region.Paper presented at the 132nd WE-Heraeus-Seminar on Positron Studies of Semiconductor Defects, Halle, Germany, 29 August to 2 September 1994 相似文献
120.