青年教师课堂教学观摩竞赛评委水平分析

评价青年教师课堂教学质量取决于青年教师教学水平及评委评判水平。本文就１９９４年山西医学院青年教师教学观摩参赛选手得分对评委评判水平进行了分析     

Numerical prediction of turbulent thermocapillary convection in superposed fluid layers with a free interface

The present paper introduces a new numerical method for predicting the characteristics of thermocapillary turbulent convection in a differentially-heated rectangular cavity with two superposed and immiscible fluid layers. The unsteady Reynolds form of the Navier–Stokes equations and energy equation are solved by using the control volume approach on a staggered grid system using SIMPLE algorithm. The turbulence quantities are predicted by applying the standard k–ε turbulence model. The level set formulation is applied for predicting the topological changes of the interface separating the two fluid layers and to provide an accurate and robust modeling of the interfacial normal and tangential stresses. The computational results obtained showed good agreement when compared with the previous experimental, numerical and analytical benchmark data for different validation cases in both laminar and turbulent regimes. The present numerical method is then applied to predict the velocity and temperature distribution in two immiscible liquid layers with undeformable interface for a wide range of Marangoni numbers. The laminar-turbulent transition is demonstrated by obtaining the turbulence features at high interfacial temperature gradient which is characterized by high Marangoni number. The effect of increasing Marangoni number on the interface dynamics in turbulent regime is also investigated.     

Damage and fracture evolution in brittle materials by shape optimization methods

This paper is devoted to a numerical implementation of the Francfort–Marigo model of damage evolution in brittle materials. This quasi-static model is based, at each time step, on the minimization of a total energy which is the sum of an elastic energy and a Griffith-type dissipated energy. Such a minimization is carried over all geometric mixtures of the two, healthy and damaged, elastic phases, respecting an irreversibility constraint. Numerically, we consider a situation where two well-separated phases coexist, and model their interface by a level set function that is transported according to the shape derivative of the minimized total energy. In the context of interface variations (Hadamard method) and using a steepest descent algorithm, we compute local minimizers of this quasi-static damage model. Initially, the damaged zone is nucleated by using the so-called topological derivative. We show that, when the damaged phase is very weak, our numerical method is able to predict crack propagation, including kinking and branching. Several numerical examples in 2d and 3d are discussed.     

效应代数的直觉模糊滤子

引入效应代数的直觉模糊滤子和它的水平滤子的概念,讨论了直觉模糊滤子与水平滤子间的关系,给出了直觉模糊滤子的等价描述,研究了直觉模糊滤子的几个运算性质。在两个经典效应代数的效应态射与效应同构意义下,讨论了这种直觉模糊滤子的像和前像问题。     

公债市场波动、消费动态与经济增长——基于递归效用与习惯形成的分析

本文在考虑公债市场波动的经济增长模型中引入递归效用和习惯形成,建立基于递归效用和习惯形成的随机经济增长模型,求得均衡时的最优消费和政府债券需求,讨论递归效用和习惯形成对最优消费和政府债券需求的影响,推导出消费的动态路径和经济增长路径,研究递归效用和习惯形成对消费动态路径和经济增长路径的影响.     

湖北随州曾侯乙墓出土玉器材质分析与产源初探

曾侯乙墓位于湖北省随州市郊,是二十世纪重大考古发现之一,其中出土玉石器数量达五百余件,且种类齐全、工艺精湛。利用现代测试仪器对这批玉石器进行全面而科学的鉴定,对于东周时期曾国用玉水平的研究具有重要的学术意义。为了探知曾侯乙墓出土玉器的玉料类型及透闪石玉料可能来源地,以其中的319件玉器为研究对象,采用宝石学与光谱学的研究思路和方法对这些样品进行无损测试。通过十倍放大镜及天平等常规宝石学检测仪器对样品的表面特征、受沁程度及种类做出初步判断,利用傅里叶变换红外光谱仪（FTIR）和X射线荧光光谱仪（XRF）快速、无损的分析出土玉器样品的矿物相及化学成分。研究结果表明,常规仪器测试结合红外光谱及X射线荧光光谱可以很好的区分出土玉器的材质,在曾侯乙墓出土的319件玉器中,有264件透闪石质玉器,43件大理岩石璧、8件云母质玉器、1件石英岩、1件萤石以及2件水晶环。XRF测试结果显示,透闪石炙玉占全部检测样品的82.8%,其主要化学成分为MgO约占20.03%～27.00%（平均值为24.46%）, SiO₂约56.31%～61.17%（平均值为58.99%）, CaO约14.25%～19.91%（平均值为15.42%）, Fe_TO约0.19%～2.06%（平均值为0.551%）,计算可知m（Mg）/m（Mg+Fe）的值在0.91~0.99之间,其测试结果范围与标准透闪石含量很接近,该批样品中未检测出阳起石质的软玉。其中,大部分优质透闪石质玉器均出土自主墓室,反映出当时人们的用玉水平及用玉习惯。根据已有研究结果,结合化学成分分析及部分具有特征风化皮层及戈壁料特征的样品,推测曾侯乙墓部分出土玉器的玉料来源于甘肃古玉矿。该结论为进一步研究曾国用玉制度和战国时期玉石之路提供了更多的研究资料。     

Submanifolds that are level sets of solutions to a second-order elliptic PDE

We consider the problem of characterizing which noncompact hypersurfaces in Rⁿ${\mathbb{R}}^n$ can be regular level sets of a harmonic function modulo a C^∞$C^{\infty }$ diffeomorphism, as well as certain generalizations to other PDEs. We prove a versatile sufficient condition that shows, in particular, that any nonsingular algebraic hypersurface whose connected components are all noncompact can be transformed onto a union of components of the zero set of a harmonic function via a diffeomorphism of Rⁿ${\mathbb{R}}^n$. The technique we use combines robust but not explicit local constructions with appropriate global approximation theorems. In view of applications to a problem posed by Berry and Dennis, intersections of level sets are also studied.     

效应代数的(η,γ]-模糊滤子

在Lu D L和Wang G J提出效应代数中模糊滤子(简称LW-模糊滤子)概念的富有成效的工作基础上,利用模糊点与模糊集的属于与重于关系给出了一种新的模糊滤子——(η,γ]-模糊滤子的定义,指出LW-模糊滤子、(∈,∈Vq)-模糊滤子和(∈,∈Vq)-模糊滤子是它的三个特例,获得了这些模糊滤子的等价刻画.     

Ocadaic acid treatment causes tyrosine phosphorylation of caveolin-2 and induces internalization of caveolae in rat peritoneal macrophages

In this paper, we provide evidences that protein phosphatases could regulate the internalization cycle of caveolae in rat peritoneal cells. Ocadaic acid (OA)—a serine/threonine phosphatase inhibitor—was used in various concentrations (4 and 100 nM) to study the internalization of horseradish peroxidase (HRP) in resident and elicited macrophages. We have found that OA in both concentrations has significantly decreased HRP uptake in resident and elicited cells. The results of our morphometrical analysis showed that in OA-treated cells, the number of surface-connected caveolae has been dramatically decreased. Simultaneously large, endosome-like vacuoles containing small vesicles appeared in the cytoplasm. The membrane of these small vesicles was labeled with anti-caveolin-1 antibody. Immunoprecipitation and Western blot analysis revealed that in OA-treated cells a 29 kDa protein identified as caveolin-2 in macrophages was phosphorylated on tyrosine residues. These data support the idea that there is a close correlation between the phosphorylation of caveolin-2 and endocytosis of caveolae: the tyrosine phosphorylation of this 29 kDa protein can drive caveolae to pinch off from the plasma membrane and causes accumulation of caveolae in a multivesicular body-like cellular compartment, which was never found to contain lysosomal enzymes. As a result of OA treatment caveolin-2 remains phosphorylated and the phosphorylation of these protein might inhibit the recycling of caveolae.