Likelihood Factorizations for Mixed Discrete and Continuous Variables

Some general remarks are made about likelihood factorizations, distinguishing parameter-based factorizations and concentration-graph factorizations. Two parametric families of distributions for mixed discrete and continuous variables are discussed. Conditions on graphs are given for the circumstances under which their joint analysis can be split into separate analyses, each involving a reduced set of component variables and parameters. The result shows marked differences between the two families although both involve the same necessary condition on prime graphs. This condition is both necessary and sufficient for simplified estimation in Gaussian and for discrete log linear models.     

基于新型图论聚类法的物流系统多设施选址策略研究

提出了一类基于图论的新型聚类算法并将其应用于物流系统中的多设施选址问题。与其他聚类算法相比,该新型算法聚类效率更高且具有更小的聚类树,从而使得有意义的聚类结果更加清晰。比较算例验证了该算法应用于多设施选址问题的高效性和实用性。     

Motivations for self-assembling into project teams

This study investigates the self-assembly mechanisms of ad hoc project teams using a bipartite network perspective. Individuals and projects are modeled as two types of nodes and team membership as relations between them. This approach enables us to investigate factors that impact voluntary team assembly at the individual, dyadic, and team levels simultaneously. Using Exponential Random Graph Models (ERGM/p*), we study players’ combat teams in a Massively Multiplayer Online Role-Playing Game (MMORPG) as a case of self-assembled project teams. Empirical results show that individuals are motivated to join ad hoc teams to complete difficult projects but not projects with long durations. We also found that individuals tend to collaborate with specific teammates who have complementary skills, those who have similar age or skill level, and those who are affiliated with the same organizational entity.     

Implementation of new technology: towards greater manufacturing flexibility

Changes in market characteristics over the past several years are forcing firms to eliminate/minimize dependency on costly buffers of capacity, lead time, or inventory. One way to accomplish this is via appropriate adaptation and enhancement of existing technological infrastructure. Recent technological advances present firms with a wide array of alternative technologies. In this paper, we discuss the impact of new technology on the manufacturing environment and the problems associated with its implementation. We present an integrated framework for implementing such technology based on a consistent hierarchy of organizational objectives and a general foundation of constraint theory.     

澳大利亚上市公司年报图形手段评介

文本与图形相结合已是当前澳洲上市公司年报篇章一大特色。文章从传播学角度统计并分析了该国50家上市公司2005年英文年报中出现的图形手段,即图片、图解和表格等信息载体,探讨了年报图形的直观性、易读性和生动性等特征,并归纳了年报图形功能,认为图形丰富了年报页面内容、增强了文本信息表述功能并强化了公司重要财务信息等。     

Using intersection matrices to identify graphical structure

Intersection matrices help identify the common graphical structure of two or more objects. They arise naturally in a variety of settings. Several examples of their use in a computer algebra environment are given. These include: simplifying an expression involving array products, automating cumulant calculations, determining the behaviour of an expected value operator and identifying model hierarchy in a factorial experiment. The emphasis is placed on the graphical structure, and the symmetry of arrays help reduce the complexity of the graphical problem.     

Robot Map Verification of a Graph World

In the map verification problem, a robot is given a (possibly incorrect) map M of the world G with its position and orientation indicated on the map. The task is to find out whether this map, for the given robot position and its orientation in the map, is correct for the world G. We consider the world model of a graph G = (V _G, E _G) in which, for each vertex, edges incident to the vertex are ordered cyclically around that vertex. (This also holds for the map M = (V _M, E _M.) The robot can traverse edges and enumerate edges incident on the current vertex, but it cannot distinguish vertices (and edges) from each other. To solve the verification problem, the robot uses a portable edge marker, that it can put down at an edge of the graph world G and pick up later as needed. The robot can recognize the edge marker when it encounters it in the world G. By reducing the verification problem to an exploration problem, verification can be completed in O(|V _G| × |E _G|) edge traversals (the mechanical cost) with the help of a single vertex marker which can be dropped and picked up at vertices of the graph world (G. Dudek, M. Jenkin, E. Milios, and D. Wilkes, IEEE Trans. on Robotics and Automation, vol. 7, pp. 859–865, 1991; Robotics and Autonomous Systems, vol. 22(2), pp. 159–178, 1997). In this paper, we show a strategy that verifies a map in O(|V _M|) edge traversals only, using a single edge marker, when M is a plane embedded graph, even though G may not be planar (e.g., G may contain overpasses, tunnels, etc.).     

论萨都剌的七言古诗

元代后期的重要诗人萨都剌是一位少数民族作家。他的七言古诗取径宽广 ,特色鲜明 ,创获显著 ,不愧是元代诗坛上的佼佼者。本文从题材内容、表现手法和艺术风格三个方面 ,对其七言古诗作了初步的探讨     

关于R(m=C4,n)图的优美性

本文对R(m=C4,n)图的优美性进行证明,同时对R(m=C4,n)图的交错性进行证明.     

卓然一家 压倒须眉——试析李清照的几首婉约词

李清照是我国文学史上最杰出的女作家 ,她对婉约词创作有自己的独特贡献。她的词善用叠字和口语 ,创造了婉曲微妙、新鲜而又隽永的独特的艺术风格。她的思妇词也有别于其它思妇之作 ,表达的是自己的真情实感