Fluid phase stability and equilibrium calculations in binary mixtures: Part I: Theoretical development for non-azeotropic mixtures

A framework is proposed for the solution of fluid phase equilibrium (P–T flash) for binary mixtures described by equations of state of general form. The framework is based on decomposing the phase equilibrium problem into sub-problems with more convenient and tractable mathematical and numerical properties. Systematic procedures are used to identify the mapping of the problem in the density and composition space, referred to as the density–composition pattern, at specified temperature and pressure. A series of stability tests is then carried out to explore the existence or non-existence of phases. Once the existence of a phase has been determined, the limits of stability and physical bounds on the problem are used to define the search area for that phase in the density–composition pattern. Finally, all available information from this detailed analysis is used for the solution of phase equilibrium between the phases identified in order to find the stable state at the specified conditions. The features of the proposed approach are exposed in detail through an algorithm for the fluid phase equilibria of the augmented van der Waals equation of state applied to non-azeotropic mixtures.     

固体材料中原子相干效应的研究进展

原子相干效应是光与物质相互作用的结果,它导致了一系列重要的物理现象。目前原子相干的实验研究工作主要在原子气体中开展,而与之相比固体材料中的相关实验研究具有更实际的应用前景。本文系统介绍了近年来固体材料中原子相干效应的研究进展,主要涉及电磁感应光透明、光速减慢与相干存储、存储光信息的可控制擦除、基于光存储的全光路由、双光脉冲的速度减慢和可逆存储和基于原子相干的增强四波混频等基本内容,最后还讨论了其在相关领域的应用。     

Characterization of the induced matching extendable graphs with 2n vertices and 3n edges

A graph $G$ is induced matching extendable or IM-extendable if every induced matching of $G$ is contained in a perfect matching of $G$. In 1998, Yuan proved that a connected IM-extendable graph on $2n$ vertices has at least $3n?2$ edges, and that the only IM-extendable graph with $2n$ vertices and $3n?2$ edges is $T\times K_2$ , where $T$ is an arbitrary tree on $n$ vertices. In 2005, Zhou and Yuan proved that the only IM-extendable graph with $2n\ge 6$ vertices and $3n?1$ edges is $T\times K_2+e$, where $T$ is an arbitrary tree on $n$ vertices and $e$ is an edge connecting two vertices that lie in different copies of $T$ and have distance 3 between them in $T\times K_2$. In this paper, we introduced the definition of $Q$-joint graph and characterized the connected IM-extendable graphs with $2n\ge 4$ vertices and $3n$ edges.     

Representing the space of linear programs as the Grassmann manifold

Each linear program (LP) has an optimal basis. The space of linear programs can be partitioned according to these bases, so called the basis partition. Discovering the structures of this partition is our goal. We represent the space of linear programs as the space of projection matrices, i.e., the Grassmann manifold. A dynamical system on the Grassmann manifold, first presented in Sonnevend et al. (Math Program 52:527–553), is used to characterize the basis partition as follows: From each projection matrix associated with an LP, the dynamical system defines a path and the path leads to an equilibrium projection matrix returning the optimal basis of the LP. We will present some basic properties of equilibrium points of the dynamical system and explicitly describe all eigenvalues and eigenvectors of the linearized dynamical system at equilibrium points. These properties will be used to determine the stability of equilibrium points and to investigate the basis partition. This paper is only a beginning of the research towards our goal. Research is supported in part by NUS Academic Research Grant R-146-000-084-112. The author wishes to thank Josef Stoer for his valuable comments on the paper and to thank Wingkeung To, Jie Wu, Xingwang Xu, Deqi Zhang and Chengbo Zhu for providing consultations on Differential Geometry and Grassmann manifolds and pointing out useful literature. The author is certainly responsible to all faults in the paper.     

The induced path function, monotonicity and betweenness

The geodesic interval function I of a connected graph allows an axiomatic characterization involving axioms on the function only, without any reference to distance, as was shown by Nebeský [20]. Surprisingly, Nebeský [23] showed that, if no further restrictions are imposed, the induced path function J of a connected graph G does not allow such an axiomatic characterization. Here J(u,v) consists of the set of vertices lying on the induced paths between u and v. This function is a special instance of a transit function. In this paper we address the question what kind of restrictions could be imposed to obtain axiomatic characterizations of J. The function J satisfies betweenness if w∈J(u,v), with w≠u, implies u∉J(w,v) and x∈J(u,v) implies J(u,x)⊆J(u,v). It is monotone if x,y∈J(u,v) implies J(x,y)⊆J(u,v). In the case where we restrict ourselves to functions J that satisfy betweenness, or monotonicity, we are able to provide such axiomatic characterizations of J by transit axioms only. The graphs involved can all be characterized by forbidden subgraphs.     

Modeling semiconductor devices by using Neuro Space Mapping

In this paper a new method for modeling semiconductor devices by use of the drift-diffusion (DD) model and neural networks is presented. Unlike the hydrodynamic (HD) model which is complicated, time consuming with high processing cost, the proposed method has lower complexity and lower simulation time. In this method the RBF neural network has been used for correcting parameters in the drift-diffusion model. Therefore solving approximate model (DD) causes to obtain accurate response. The proposed method is first applied to a silicon n-i-n diode in one dimension, and then to a silicon thin-film MOSFET in two-dimensions, both for interpolation and extrapolation. The obtained results for basic variables, i.e., electron and potential distribution for different voltages, confirm the high efficiency of the proposed method.     

L-预拓扑空间中模糊网的O-收敛及其应用

利用L-点的邻域研究了L-预拓扑空间中模糊网的O-收敛性,在此基础上刻画了L-预拓扑空间中的闭集、开集以及模糊紧集,并给出T2L-预拓扑空间的两个判据。     

On Inverse Limits and Direct Limits for Fuzzy Topological Spaces

Li has introduced the concepts of inverse system and direct system for fuzzy topological spaces and studied inverse limits and direct limits on such spaces by presenting the explicit constructions of these limits.In this paper some important concepts of fuzzy topology,such as,product fuzzy topology,quotient fuzzy topology,fuzzy continuity etc.,are used for further study of inverse limits and direct limits for fuzzy topological spaces.     

直觉模糊度量空间上的半群作用

讨论在直觉模糊度量空间上的拓扑半群作用,引入诸如拓扑传递性,点传递性及点稠传递性等概念.考虑非敏感性与传递性,等度连续等动力学性质的相互关系.     

FTIR用于第4代太空诱变育种黄芩的分析

首次从整体上测定并对比分析了我国独创的太空诱变育种黄芩和地面组黄芩,以期为全面了解第4代太空诱变黄芩品质的变化和深入研究积累资料.结果表明两组样品的FTIR光谱的主要吸收峰的峰位、峰形大致相同,但吸收峰的强度却有明显差异,太空组黄芩中各主要吸收峰强度都比地面组明显增强,尤其是黄芩的主要活性成分黄酮类化合物(黄芩甙、黄芩素、汉黄芩甙、汉黄芩素及黄芩新素等)在3 391,1 655,1 069 cm-1等处吸收峰强度明显比地面组增强,说明太空组黄芩中主要活性成分黄酮类化合物及其他成分含量比地面组明显提高.这表明太空组黄芩的非晶态活性成分明显得到了优化.太空诱变育种有利于选育出活性成分提高的黄芩新品种,是中药材种质资源创新的快捷有效的途径之一.