Nonlinear progressive damage model for composite laminates used for low-velocity impact

In order to effectively describe the progressively intralaminar and interlam- inar damage for composite laminates, a three dimensional progressive damage model for composite laminates to be used for low-velocity impact is presented. Being applied to three-dimensional （3D） solid elements and cohesive elements, the nonlinear damage model can be used to analyze the dynamic performance of composite structure and its failure be- havior. For the intralaminar damage, as a function of the energy release rate, the damage model in an exponential function can describe progressive development of the damage. For the interlaminar damage, the damage evolution is described by the framework of the continuum mechanics through cohesive elements. Coding the user subroutine VUMAT of the finite element software ABAQUS/Explicit, the model is applied to an example, i.e., carbon fiber reinforced epoxy composite laminates under low-velocity impact. It is shown that the prediction of damage and deformation agrees well with the experimental results.     

自旋极化对Kondo系统基态的影响

Anderson模型中的自旋极化效应是一个普遍存在的问题.本文从Anderson杂质模型出发,利用变分及对角化方法分析了自旋极化所引起的系统基态性质的改变,分别研究了自旋极化对Kondo单态以及高温超导两分量模型中Zhang-Rice单态稳定性的影响问题.     

高温超导体的电子结构、反铁磁交换和磁性超导机制

高温超导体中电子的自旋和电荷一样重要。文章对高温超导体的电子结构、磁性相互作用和关于单胞层La1.85Sr0.15CuO4存在超导态的最新实验结果作了扼要的介绍，并指出，电子的有效自旋耦合应当是产生高温超导电性的原因。     

N-咪唑基乙酸乙酯的合成及其缓蚀性能

缓蚀剂;铜;N-咪唑基乙酸乙酯的合成及其缓蚀性能     

共用天线电视系统中的几个物理问题

共用天线电视系统中的几个物理问题马宗廉张延生郭卫刘筑闻蔺利峰（首都医科大学北京１０００５４）于韶光（北京电子报社北京１００００５）（收稿日期：１９９６０７２９）共用天线电视系统，其英文名称是ＣｏｍｍｕｎｉｔｙＡｎｔｅｎｎａＴｅｌｅｖｉｓｉｏｎ故...     

氯霉素兽药纯度标准物质的研制

对市售氯霉素原料经提纯后研制兽药标准物质,采用熔点、红外和质谱法对提纯后氯霉素样品进行定性鉴定,采用高效液相色谱法进行定量分析.探讨了高效液相色谱法分析检测氯霉素兽药的分离与检测条件.试验发现氯霉素在甲醇溶剂中不稳定,在乙腈溶剂中稳定性提高.采用多家实验室联合分析的方法对标准物质进行定值.研制的氯霉素标准物质的纯度为99.7%,定值结果不确定度为0.3%(k=2).     

一种酸洗缓蚀剂的合成及缓蚀性能研究

咪唑啉类化合物能够提供π电子和杂原子使其吸附在金属表面,从而达到缓蚀作用。而分子中不饱和键的引入有助于缓蚀效率的提高。用苯甲醛、三乙烯四胺及丙烯酸为原料合成了咪唑啉型化合物SEI,进行了IR表征,     

Electron Spin Pairing and Excitations in High—Tc Superconductors

Effective spin coupling between conduction electrons mediated by local Cu moments in the doped CuO2 plane may induce the instability of the normal states of conduction electrons and pairing at Cu stes,where the superexchange interaction between local moments influenced by hole doping has been found to be Ising-like in recent experiments.By a mean field approach,we show that spin pairing and strong pair-pair interaction in the doped antiferromagnetic ordered Ising-like CuO2 plane gives rise to high-temperature superfluid condensation and the exceptional features of quasi-particle excitation in cuprates such as spin gap,pseudogap,and the linear temperature dependence of resistivity ρab in the normal states.