Graphical fault tree analysis for fatal falls in the construction industry

The current study applied a fault tree analysis to represent the causal relationships among events and causes that contributed to fatal falls in the construction industry. Four hundred and eleven work-related fatalities in the Taiwanese construction industry were analyzed in terms of age, gender, experience, falling site, falling height, company size, and the causes for each fatality. Given that most fatal accidents involve multiple events, the current study coded up to a maximum of three causes for each fall fatality. After the Boolean algebra and minimal cut set analyses, accident causes associated with each falling site can be presented as a fault tree to provide an overview of the basic causes, which could trigger fall fatalities in the construction industry. Graphical icons were designed for each falling site along with the associated accident causes to illustrate the fault tree in a graphical manner. A graphical fault tree can improve inter-disciplinary discussion of risk management and the communication of accident causation to first line supervisors.     

Evolution of railway network flexibility: The Spanish broad gauge case

The length of the Spanish broad gauge network has decreased in the 1956–2006 period. When looking at different railway maps through this period, it seems that the network is offering fewer and fewer alternatives when a line is cut, that is, the network is becoming less and less flexible. The goal of this article is to prove that the flexibility of the Spanish broad gauge network has decreased substantially in the 1956–2006 period. We have considered the network as a graph (ignoring traditional railway quality indicators such as commercial speed, number of tracks, electrifications, signaling, …) and we have chosen two simple indicators as accurate in this sense: the number of cycles (cycles provide an alternative to reach a station if there is a problem in one line) and the number of stations of intermediate degree. To achieve this, we have developed a piece of software that is an ad hoc extension of Maple’s networks package.     

Complete and ready simulation semantics are not finitely based over BCCSP, even with a singleton alphabet

This note shows that the complete and the ready simulation preorders do not have a finite inequational basis over the language BCCSP when the set of actions is a singleton. Moreover, the equivalences induced by those preorders do not have a finite (in)equational axiomatization either. These results are in contrast with a claim of finite axiomatizability for those semantics in the literature, which was based on the erroneous assumption that they coincide with complete trace semantics in the presence of a singleton set of actions.     

基于双子代数理论的网络建模与分析

本文研究了双子代数尤其是极大代数理论在计算机网络建模与性能分析中的应用.采用极大代数分析了令牌桶的输入输出特性,得到了(b,ρ)令牌桶在极大代数下的状态空间方程组与传输矩阵;提出了基于极大代数的网络演算,定义了极大到达曲线与极大服务曲线,利用这两个概念得出了极大代数下有关延迟以及输出流突发性的定理.最后采用基于极大代数...     

右-右缠绕模范畴M_A~C(Ψ)中的扭曲

主要推广了关于相关Hopf模的扭曲理论到缠绕模上,证明(A,C,Ψ)上的右-右缠绕模范畴MCA(Ψ)同构于(Aτ,C,Ψ)上的右-右缠绕模范畴MACτ(Ψ),从而发展了缠绕模的理论。     

Reconstruction from Projections Using Grassmann Tensors

In this paper a general procedure is given for reconstruction of a set of feature points in an arbitrary dimensional projective space from their projections into lower dimensional spaces. This extends the methods applied in the well-studied problem of reconstruction of scene points in ℘³ given their projections in a set of images. In this case, the bifocal, trifocal and quadrifocal tensors are used to carry out this computation. It is shown that similar methods will apply in a much more general context, and hence may be applied to projections from ℘ ⁿ to ℘ ^m , which have been used in the analysis of dynamic scenes, and in radial distortion correction. For sufficiently many generic projections, reconstruction of the scene is shown to be unique up to projectivity, except in the case of projections onto one-dimensional image spaces (lines), in which case there are two solutions. Projections from ℘ ⁿ to ℘² have been considered by Wolf and Shashua (in International Journal of Computer Vision 48(1): 53–67, 2002), where they were applied to several different problems in dynamic scene analysis. They analyzed these projections using tensors, but no general way of defining such tensors, and computing the projections was given. This paper settles the general problem, showing that tensor definition and retrieval of the projections is always possible.     

Dynamic Min-Max Problems

In this paper a method to check the solvability of a set of linear equations in the (max, min, +) algebra is described. Then, extensions to dynamic (or periodic) systems in the (max, min, +) algebra are provided. Further, some results regarding the uniqueness of solutions in both cases are given. Finally, we address a more general quasi periodic problem and provide an algorithm for its solution.     

A computer algebra based finite element development environment

A finite element development environment based on the technical computing program Mathematica is described. The environment is used to automatically program standard element formulations and develop new elements with novel features. Source code can also be exported in a format compatible with commercial finite element program user-element facilities. The development environment is demonstrated for three mixed Petrov–Galerkin plane stress elements: a standard formulation, an advanced formulation incorporating rotational degrees of freedom and a standard formulation in which the stiffness matrix is integrated analytically, before being exported as ANSYS user elements. The results presented illustrate the accuracy of the standard mixed formulation element and the enhancement of performance when rotational degrees of freedom are added. Further, the analytically integrated element shows that computational requirements can be greatly reduced when analytical integration schemes are used in the formation.     

概念代数在本体合并中的应用

本体合并是本体集成的一种较为有效的方式,是用于解决本体异构以实现本体资源重用和共享的一种方法。引入概念代数以弥补本体的概念深度表达不够、形式化程度低等缺陷。将本体与概念代数结合,提出一种基于概念代数的本体表示方法,其恰好符合领域专家构建本体的意识活动,可以更好地表达和处理知识。概念代数是一种抽象的数学结构,形式化程度较高,并且其概念之间的认知关系更便于进行知识推理。利用概念代数将本体表示为可视化的概念网形式,进而利用概念代数的运算实现概念之间的合并及关联,提出一种基于概念代数的本体合并方法,是对概念代数应用到本体的一种尝试,为本体的处理提供了一个新的视角。