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排序方式: 共有7480条查询结果,搜索用时 15 毫秒
971.
A. Chiron B. Lamouroux R. Lange J.-F. Ripoche M. Franco B. Prade G. Bonnaud G. Riazuelo A. Mysyrowicz 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(3):383-396
A two-dimensional axisymmetric model of the propagation of intense femtosecond laser pulses through dispersion-free transparent
media is described. The effects of diffraction, nonlinear Kerr effect (instantaneous and retarded) and multiphoton ionisation
are included. Numerical results concerning air and other gases are discussed. In particular, time self-compression of femtosecond
pulses is predicted. Stable self-guided pulses are simulated, in agreement with recent experimental observations.
Received: 19 June 1998 / Received in final form: 14 January 1999 相似文献
972.
An anisotropic medium is considered in which, upon loading, scattered microdamages accumulate giving rise to nonlinear and
residual strains. The damage at a point of the medium is characterized by a scalar function on a unit sphere, referred to
as the damage function. This function is approximated by a fourth-rank tensor used for specifying the relation between the
increments of strains and stresses. The calculation dependences are presented in detail for a unidirectional composite, which
is taken to be a homogeneous transversely isotropic medium. Determination of the unknown constants is illustrated by the example
of an actual fiberglass plastic.
Institute of Polymer Mechanics, University of Latvia, Riga, LV-1006, Latvia. Translated from Mekhanika Kompozitnykh Materialov,
Vol. 35, No. 5, pp. 561–574, September–October, 1999. 相似文献
973.
§1.IntroductionRecently,Liandotherauthorsdidextensiveanddeepresearchonthetheoryandap-plicationofgeneralizeddiferencemethods(s... 相似文献
974.
975.
无失效数据失效率的综合多层Bayes估计 总被引:5,自引:1,他引:4
文章对指数分布无失效数据的失效率,在先验分布为Gamma分布时,在引进失效信息后,给出了多层Bayes估计以及综合多层Bayes估计,并给出了可靠度的综合估计。最后,结合实际问题进行了计算 相似文献
976.
A normal mode method for propagation modeling in common horizontally stratified shallow water, which is called beam-displacement
ray-mode (BDRM) theory, is introduced. The peculiarity of this method is that the boundary effects on the sound field can
be expressed by the equivalent boundary reflection coefficient, so BDRM theory can be extended to elastic bottom easily. Theoretical
calculations of shallow-water sound field show that BDRM has high accuracy and fast speed. The pulse propagation in shallow
water is also calculated by BDRM, and the calculated waveforms are in good agreement with the measured waveforms.
Project support by the National Natural Science Foundation of China (Grant No. 1973405). 相似文献
977.
流体动力润滑油膜破裂的热力学失稳机理 总被引:1,自引:0,他引:1
分析了流体动力学润滑过程中的热量传递及对润滑剂流变特性的影响,得出了流体动力润滑油膜发生热力学失稳的条件,建立了描述润滑剂温度非牛顿效应的本构方程数值计算结果表明,由于温度的影响,流体动力润滑油膜存在最大承载能力;在临界状态,微小的扰动将会引起油膜失稳而丧失承载能力。初步揭示了流体动力学力润滑膜破失效的内在力学机制。 相似文献
978.
非线性振动一种稳定的模糊控制方法研究 总被引:2,自引:0,他引:2
由于非线性振动系统的非线性本质,在于传统控制理论的线性控制器用于非线性振动控制效果不佳。本文针对非线性振动系统提出了一种模糊自适应滑模控制方案。 相似文献
979.
Modern thermal analysis, microcalorimetry and new emerging combined techniques which deliver calorimetric, microscopic and
spectroscopic data offer a powerful analytical battery for the study of pharmaceuticals. These techniques are very useful
in all steps of development of new drug products as well as methods for quality control in production. The characterization
of raw materials enables to understand the relationships between polymorphs, solvates and hydrates and to choose the proper
development of new drug products with very small amount of material in a very short time. Information on stability, purity
is valuable for new entities as well as for marketed drug substances from different suppliers. Excipients which vary from
single organic or inorganic entity to complexes matrixes or polymers need to be characterized and properly controlled. The
thermodynamic phase-diagrams are the basis of the studies of drug-excipients interactions. They are very useful for the development
of new delivery systems. A great number of new formulations need proper knowledge of the behaviour of the glass transition
temperature of the components. Semi-liquid systems, interactions in aqueous media are also successfully studied by these techniques.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
980.
含72元环的二维网状结构超分子配合物的合成与结构 总被引:3,自引:2,他引:1
用自组装方法合成具有特殊网状结构及光学、电学、磁学、离子或分子交换、催化等性能的化合物的分子工程学和超分子化学近年来成为人们研究的热点,并已取得了很大进展[1,2].当前常用的一种三角架结构单元是刚性芳基三角架配体[3~5],而对柔性芳基三角架配体及... 相似文献