Microstress estimate of stochastically heterogeneous structures by the functional perturbation method: A one dimensional example

A new functional perturbation method (FPM) for calculating the probabilistic response of stochastically heterogeneous, linear elastic structures is developed. The method is based on treating the governing differential operator as well as the unknown displacement function as a functional of material modulus field. By executing a functional perturbation around the homogeneous case, a set of successive differential equations is obtained and solved, from which the average and variance of any local parameter (displacements, stresses, strains) can be found. For a linear problem, the equations to be solved in each approximation order differ from the one for the homogeneous case by a pseudo external loading (right hand side) part only. Thus, only the Green function for the homogeneous case is needed for an analytical solution of the corresponding heterogeneous problem. A one dimensional stochastically heterogeneous rod embedded in a uniform shear resistant elastic medium is solved as an example. The statistical variance of displacements and stresses are found analytically, including the edge regions. Morphological (grain size) and material (modulus) effects on the stochastic response are demonstrated. The above results are essential for estimating the stochastic features of local stress concentrations, which are the source for many strength-related macro properties of materials. Extensive usage of generalized functions (Dirac operator and its derivatives) is needed for the analysis.     

超临界流体中的酶催化

与其他非水相酶催化介质相比 ,超临界流体有其独特的优越性。阐述了超临界流体的概念、对超临界流体的选择原则以及在超临界流体中酶催化的各种影响因素 ,还讨论了在此类流体中酶催化的应用和发展前景     

二次电池电极基板用复合多孔金属材料的研究

介绍了一种复合金属多孔体的制备及其方法，首先以泡沫塑料为芯膜，经过导电化处理使其具有导电性，其次进行电沉积金属铁，再进行电沉积金属镍，经过热处理后可制备出复合金属多孔体。该复合金属多孔体用铁取代金属镍，其抗拉性能优于单质泡沫镍，同时可以降低制造成本，主要用于载体如电池电极。     

多孔粒状铵油炸药在乌海矿业公司的应用

通过对多孔粒状铵油炸药质量影响因素的分析，结合乌海矿业公司爆破的特点，提出了保证炸药加工质量的合理参数。     

Media ratings for violence and sex: Implications for policymakers and parents.

This article reviews research on the implementation of media-rating systems, parents' use and evaluation of them, and the impact of ratings on children. Although half or more of parents report using media-rating systems, understanding of various components of the systems is low, particularly for television ratings. A meta-analysis of national polls shows that parents overwhelmingly prefer that ratings specify content, rather than giving age recommendations. A second meta-analysis, of experiments testing the effects of ratings on children's interest in programs, shows that ratings indicating restricted or controversial content have a deterrent effect for children under age 8 but that, by age 11 and especially for boys, the ratings show a small enticement effect. This effect occurs for both age-based and content-based ratings. Implications for policymakers and parents are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

多孔材料气体流量的简便计算

采用简便方法计算气体通过多孔材料的流量。当层流时，流量与压差按线性关系计算；紊流时，应按幂函数关系计算。本文提出了计算公式。     

Optimized Schwarz methods without overlap for highly heterogeneous media

In this paper an original variant of the Schwarz domain decomposition method is introduced for heterogeneous media. This method uses new optimized interface conditions specially designed to take into account the heterogeneity between the sub-domains on each sides of the interfaces. Numerical experiments illustrate the dependency of the proposed method with respect to several parameters, and confirm the robustness and efficiency of this method based on such optimized interface conditions. Several mesh partitions taking into account multiple cross points are considered in these experiments.     

Mortar finite element discretization for the flow in a nonhomogeneous porous medium

Darcy’s equations model the flow of a viscous incompressible fluid in a rigid porous medium. One of the parameters of the system depends on the permeability of the medium and, when this medium is not homogeneous, the variations of the parameter could be very high. To handle this phenomenon, we propose a discretization of the model that relies on the mortar finite element method. Indeed, the idea is to construct a decomposition of the domain such that the permeability is constant on each element of the partition and to use independent meshes on the different subdomains. We perform the a priori and a posteriori analysis of this discretization and present some numerical experiments which are in good coherency with the results of the analysis.     

IPTV及相关技术

IPTV是基于IP协议的新一代技术,介绍了IPTV的主要业务功能和系统组成,并阐述了IPTV系统的关键技术。     

利用分形几何确定多孔介质的孔尺寸分布

提出了利用分形几何确定多孔介质孔尺寸分布的方法。考虑多孔介质中孔间的屏蔽，采用此方法得到的孔尺寸分布范围比采用平行孔模型宽，分别采用本方法和平行孔模型测定γ－Al2O3催化剂的孔尺寸分布，构造简单立方体三维网络模型模拟压汞过程，并将模拟曲线与γ－Al2O3压汞实验曲线比较，结果表明，采用本方法所得孔尺雨分布优于平行孔模型所得孔尺寸分布。