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91.
92.
N[a,b]类中边界Nevanlinna-Pick插值(I) 总被引:1,自引:1,他引:0
用所谓的Hankel向量方法求解N[a,b]函数类中带边界插值数据的Nevanlina-Pick插值(BNP(N[a,b]))问题,并建立BNP(N[a,b])问题与[a,b]上的某种带约束条件的Hausdorff矩量问题之间等价的可解条件以及解之间明确的一一对应关系.这使得当BNP(N[a,b])问题有多解时,能通过带约束条件的矩量问题的可解性准则和解获得BNP(N[a,b])问题的可解性准则和解的参数化描述,而在唯一解的情况下,通过BNP(N[a,b])问题解的存在唯一性准则和唯一解来获得带约束条件的 相似文献
93.
利用光热偏转技术实施光学薄膜弱吸收的多波长测量 总被引:2,自引:0,他引:2
介绍了光热表面形变光束偏转技术用于测量光学薄膜弱吸收的基本原理,简述多波长吸收测量装置的建立和测试过程,最后给出简单的测量实例. 相似文献
94.
我们对多电子束契伦柯夫自由电子激光进行了首次实验研究。280A,500kV的电子束被引入一多介质矩形谐振腔,在频率为33.4GHz处产生了1.7MW的契伦柯夫相干受激辐射。互作用效率为1.2%。 相似文献
95.
Ge segregation during the growth of Si1 − xGex alloys (x = 5, 10, 20, and 40%) was studied using X-ray photoelectron spectroscopy. The alloys were grown in thicknesses up to 20.0 nm at 500°C to measure quantitatively the amount of segregated surface Ge. The length of alloy needed to reach steady-state growth edge was found to decrease with increasing alloy concentration (4.8, 2.8, 2.4, and 2.0 nm, respectively). It was found that each alloy had a complete monolayer of Ge on the surface and an increasing amount of segregated Ge in the second layer (20, 55, 80, and 95%, respectively) during steady-state growth. An increase in the temperature of alloy growth (400–750°C) resulted in an increase in the leading edge of alloy growth but did not change the amount of segregated Ge during steady-state growth. We propose that film stress is responsible for the amount of Ge segregation. 相似文献
96.
A. C. Orifici R. S. Thomson R. Degenhardt C. Bisagni J. Bayandor 《Mechanics of Composite Materials》2007,43(1):9-28
Analysing the collapse of skin-stiffened structures requires capturing the critical phenomenon of skin-stiffener separation,
which can be considered analogous to interlaminar cracking. This paper presents the development of a numerical approach for
simulating the propagation of interlaminar cracks in composite structures. A degradation methodology was introduced in MSC.Marc,
which involved the modelling of a structure with shell layers connected by user-defined multiple-point constraints (MPCs).
User subroutines were written that employ the virtual crack closure technique (VCCT) to determine the onset of crack growth
and modify the properties of the user-defined MPCs to simulate crack propagation. Methodologies for the release of failing
MPCs are presented and are discussed with reference to the VCCT assumption of self-similar crack growth. The numerical results
obtained by using the release methodologies are then compared with experimental data for a double-cantilever beam specimen.
Based on this comparison, recommendations for the future development of the degradation model are made, especially with reference
to developing an approach for the collapse analysis of fuselage-representative structures.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 43, No. 1, pp. 15–42, January–February, 2007. 相似文献
97.
In this paper, we discuss the detailed optical design of a beam line that is under construction on the synchrotron radiation source, Indus-1. Toroidal mirrors are used as pre-and post- focusing elements and a toroidal grating monochromator as a dispersing element. Using three interchangeable gratings, this monochromator will give, at a moderate resolution, a good throughput on the sample in the wavelength range 40 to 1000 Å. Effect of various parameters and their optimization on the resolution and throughput characteristics have been studied by ray tracing calculations, and presented. 相似文献
98.
高斯光束照射下的圆盘夫琅禾费衍射 总被引:9,自引:3,他引:6
推导了高斯光束照射圆孔或圆盘的衍射场普遍表达式,计算了半波带数接近于零的情况下上述衍射场的数据,进而分析了圆盘衍射场在艾里斑中增加一个暗环的原因。 相似文献
99.
100.
Mei‐Jiau Huang 《国际流体数值方法杂志》2005,48(5):521-539
The technique of splitting a fat vortex element (with a core width larger than some threshold) into some thin ones in order to fix the convergence problem of the core‐spreading vortex methods is convenient and efficient. In particular, it keeps the method purely Lagrangian. In the present investigation, the splitting process is further viewed as part of the physical diffusion process. A new splitting method in which several weaker child vortices surround a thinned but still strong parent vortex is proposed. It is found that because of the survival of the parent vortex, the error arising from the splitting events can be largely reduced. The computational amount on the other hand is kept reasonably large by merging similar and close‐by vortices. The merging scheme designed herein not only involves fewer restrictions but also allows merging vortices of opposite rotations through the viewpoint of remeshing. The validity and accuracy of these techniques, proposed particularly for simulations undergoing lots of splitting and merging events, are verified by successfully simulating the interactions between two Burgers vortices under an external straining field. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献