二维弹性结构入水冲击过程中的流固耦合效应

描述了一个研究弹性结构入水冲击过程中水弹性效应的数值方法,在弹性结构入水冲击过程中,流体域作用在结构上的水动力载荷由边界元法获得,而结构的弹性动力响应则由有限元方法求解,通过线性给离散Ｂｅｒｎｏｕｌｌｉ方程将有限元方程和边界元方程耦合到一起,从而获得了求解流场和结构动力响应的相互耦合的运动方程。在数值考虑了自由表面的非线性边界条件,通过引入射流单元以及最大射流厚度,较好地处理了冲击引起的射流问题。     

金属络合物分子间交换反应的核磁共振研究Ⅲ.噻吩甲酰三氟丙酮铝与苯甲酰丙酮铝体系分子间配体交换的19F NMR研究

用¹⁹F NMR研究了噻吩甲酰三氟丙酮铝与苯甲酰丙酮铝体系分子间的团体交换反应,求得了交换反应的平衡常数及自由能,结果表明交换反应有利于混合配体络合物生成,平衡时混和溶液中各组分分布偏离统计分布。     

F／Cl比与Eu~（2＋）：BaFCl中F色心的浓度和光激励截面的关系

研究了Ｅｕ（２＋）：ＢａＦｘＣｌ２在紫外线辐照下的光激励发光。通过改变激励方式及激励光的扫描方向，给出了Ｅｕ（２＋）：ＢａＦｘＣｌ２－ｘ光激励发光过程中，两种Ｆ色心的浓度比值与光激励截面比值的测定方法。利用这种测定方法，进一步研究了两种Ｆ色心的浓度比值和光激励截面比值与Ｆ／ＣＩ比值的关系。     

osp(N, 2) AKNS equations

The osp(N, 2) extension of the AKNS scheme is reconsidered. It leads to a general class of integrable nonlinear evolution equations for 2+N(N–1)/2 commuting and 2N anticommuting fields. by reduction, various osp(N, 2) versions of the Korteweg-de Vries equation can be obtained. One of these is shown to be bi-Hamiltonian and its second Hamiltonian structure corresponds to the classical limit of the so(N) superconformal algebra. The nonlinear Schrödinger and modified Korteweg-de Vries reductions are also briefly discussed.Work supported by NSerc and FCAR.     

Influence of end reflectivity on gain saturation in a planar distributed feedback laser

An approximate method for the analysis of planar-waveguide distributed-feedback lasers is extended to include a nonvanishing reflectivity at the ends of the structure. An index grating structure with parasitic losses is investigated. An expression for the small-signal gain coefficient ^0MN as a function of the output power P ^MNout normalized to the saturation power P ^s , coupling coefficient K, complex reflectivity R of end reflectors, and waveguide parameters is presented.     

Frequency stability of an optically pumped cesium beam frequency standard

Results obtained in an experimental optically pumped cesium beam frequency standard in which a single semiconductor laser is used for the state selection and the atom detection are reported. The separation between the two interaction regions is equal to 21 cm. This gives a 500 Hz linewidth which is observed with a signal to noise ratio equal to 10,000 in a 1 Hz noise bandwidth. A quartz crystal oscillator is frequency controlled by the atomic transition. The measured short term frequency stability is given by _y()=2×10^–12–1/2 for 1 s<500 s. Prospects for improvement of this frequency stability are discussed.     

Energy theory of waveguide distributed feedback gas lasers

In this paper systematic numerical studies of the nonlinear operation of a waveguide distributed feedback gas laser equipped with a metal waveguide of rectangular cross section are presented. An approximate formula relating small-signal gain with the output power and the parameters of the structure for this kind of lasers is derived. Characteristics revealing saturation effects for weak as well as strong coupling regions are presented.Academic guest from the Institute of Microelectronics and Optoelectronics, Technical University, Warsaw, Poland     

InGaP光学微盘的显微荧光图像观测及分析

利用一套ＣＣＤ显微荧光图像观测和采集分析系统,分别在室 液氮温度下对半径为５μｍ发射波长０．６５μｍ的ＩｎＧａＰ半导体光学微盘的光图像进行了观测。     

Some properties of biwave maps

We study biwave maps and equivariant biwave maps. We obtain the formulations for equivariant biwave maps into various spaces by applying eigenmaps between spheres. We compute the biwave fields of inclusions into warped product manifolds and construct examples of biwave maps. We finally investigate the stress bi-energy tensors and the conservation laws of biwave maps.     

19F NMR化学位移经验公式的影响因素

化学位移是核磁共振技术的重要参数,目前对¹H NMR、¹³C NMR已提出一系列估算化学位移的经验公式,但¹⁹F NMR化学位移规律研究报道则较少,以δ=B+∑△i+C化学位移通式为基础,分析屏蔽常数对化学位移的作用,并针对¹⁹F原子,分析了氟的电子云密度、立体效应、溶剂效应、氢键、标准、浓度和温度等影响因素,对¹⁹F NMR化学位移经验公式的提出提供理论依据。