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61.
By solving the time-dependent Schro¨dinger equation, the dependence of photoelectron energy spectra on the binding energy of targets, wavelength and the intensity of laser pulse is exhibited and a scaling law of kinetic energy spectra of both the direct and the rescattered photoelectrons is concluded. The scaling law provides a convenient tool to determine the equivalent photoionization process of various atoms or molecules in various laser fields. The verification of the scaling law by independent methods provides incontestable support to the validity of the scaling law. 相似文献
62.
The refraction holodiagram RHD is analyzed here with respect to the law of refraction. Particularly, we study the surface that exactly conjugates by refraction a virtual point source with a real image or conversely. By using the total optical path as a parameter we build a diagram that consists in a family of Descartes ovals of the apple type that contains the Pascal's limaçon as a particular extreme case and the spherical surface with the Weierstrass points as another. These representations permit the straightforward application of Fermat's principle in the case of arbitrary refracting surfaces and show the shape of generalized Fresnel's zones in the intersections with any surface. Snell's law is applied to rays incident on the apple type surfaces to find out the conditions for exact conjugation. Sensitivity to optical path variations is also discussed. The RHD curves family can be represented in a Cartesian way where the ovals appear as equally spaced straight lines. 相似文献
63.
We study GaN/AlN Quantum Dot (QD) superlattices utilizing the STREL environment which allows the building of atomistic models, relaxation of the structures, the calculation of the electronic states and optical transitions and the visualization of the results. The forces are calculated using an appropriate Keating or Stillinger–Weber interatomic potential model and the electronic states and optical transitions using a tight-binding formulation which is economical and produces realistic electronic properties. The relaxed structure has strains mainly in the GaN region which are compressive and small tensile strains in the AlN region, mainly below the QD. In the calculation of the electronic states and of the optical transitions the strains are included realistically at the atomistic level. The study of the wavefunctions close to the fundamental gap show how these strains influence the form and spatial extent of the wavefunction. Very close to the fundamental gap the valence and some conduction states are confined in the QD and have considerable oscillator strength. 相似文献
64.
文章根据毕-沙定律、电流回路元和载流线圈的费曼模型,用普通物理的方法计算出载流线圈在远处一点的磁场分布。 相似文献
65.
66.
研究等待时间分布为截断幂律分布的连续时间随机行走(CTRW)模型,分析比较截断幂律分布的可能随机抽样方法,并提出一套可以对其进行精确抽样的乘分布舍选算法.数值结果表明:当幂律指数α > 0.2时,该算法的抽样效率在80%以上.利用该算法可以成功得出CTRW模型描述的三种反常输运过程的标度关系. 相似文献
67.
A New Higher Order Shear Deformation Model for Static Behavior of Functionally Graded Plates 下载免费PDF全文
Tahar Hassaine Daouadji Abdelouahed Tounsi & El Abbes Adda Bedia 《advances in applied mathematics and mechanics.》2013,5(3):351-364
In this paper, a new displacement based high-order shear deformation theory is introduced
for the static response of functionally graded plate. Unlike any other theory, the number
of unknown functions involved is only four, as against five in case of other shear deformation
theories. The theory presented is variationally consistent, has strong similarity with
classical plate theory in many aspects, does not require shear correction factor, and
gives rise to transverse shear stress variation such that the transverse shear stresses
vary parabolically across the thickness satisfying shear stress free surface conditions.
The mechanical properties of the plate are assumed to vary continuously in the thickness
direction by a simple power-law distribution in terms of the volume fractions of the
constituents. Numerical illustrations concerned flexural behavior of FG plates with
Metal-Ceramic composition. Parametric studies are performed for varying ceramic volume
fraction, volume fraction profiles, aspect ratios and length to thickness ratios. The
validity of the present theory is investigated by comparing some of the present results
with those of the classical, the first-order and the other higher-order theories. It
can be concluded that the proposed theory is accurate and simple in solving the static
behavior of functionally graded plates. 相似文献
68.
提出普遍定律和非普遍定律以及“协变”与“可导出”的明确定义,证明狭义相对性原理(及其伽利略近似)要求在惯性系变换下,自然界普遍定律是协变的,非普遍定律不协变但是“可导出”的,一切定律都服从相对性原理,从而进一步解答了由爱因斯坦,朗道关于狭义相对性原理的一种错误表述所引起的“协变性疑难”,还将有关结论推广到广义相对性原理情况。 相似文献
69.
按照新课程标准的要求,针对高中物理粤版选修教材中存在的不足,在制作原电池方面做了相应的改进.用重铬酸钾做电解质溶液中的氧化剂,用蓬松棉做盐桥,并用碳棒做电池正极.同时将该方法制做的原电池引入探究原电池内电压和外电压的关系和电池内电阻的大小2个实验中. 相似文献
70.
W. Götze 《Journal of statistical physics》1996,83(5-6):1183-1197