Issues in the estimation and application of latent structure models of choice

Our paper provides a brief review and summary of issues and advances in the use of latent structure and other finite mixture models in the analysis of choice data. Focus is directed to three primary areas: (1) estimation and computational issues, (2) specification and interpretation issues, and (3) future research issues. We comment on what latent structure models have promised, what has been, to date, delivered, and what we should look forward to in the future.     

三线铁路荷载作用下箱梁桥荷载横向分布系数

文章运用有限元程序对三线铁路预应力混凝土连续箱梁桥进行了模拟,分析了三线铁路荷载作用下箱梁的受力特性及在各种荷载工况下荷载横向分布规律,给出了荷载横向系数的实用值。     

EMBEDDED MATRICES FOR FINITE MARKOV CHAINS

For an arbitrary subset A of the finite state space 5 of a Markov chain the so–called embedded matrix P _A is introduced. By use of these matrices formulas expressing all kinds of probabilities can be written down almost automatically, and calculated very easily on a computer. Also derivations can be given very systematically.     

公路桥梁的抗震分析

文章针对公路桥梁,利用有限元方法分析在地震载荷下的应力分布规律,为桥梁抗震设计提供依据。     

Progressive stress accelerated life tests under finite mixture models

In this paper, progressive stress accelerated life tests are considered when the lifetime of a product under use condition follows a finite mixture of distributions. The experiment is performed when each of the components in the mixture follows a general class of distributions which includes, among others, the Weibull, compound Weibull, power function, Gompertz and compound Gompertz distributions. It is assumed that the scale parameter of each component satisfies the inverse power low, the progressive stress is directly proportional to time and the cumulative exposure model for the effect of changing stress holds. Based on type-I censoring, the maximum likelihood estimates (MLEs) of the parameters under consideration are obtained. A special attention is paid to a mixture of two Rayleigh components. Simulation results are carried out to study the precision of the MLEs and to obtain confidence intervals for the parameters involved.     

分布式并行计算网格系统的设计与实现

基于网格计算技术提出了一种分布式的有限元并行计算网格系统的原型DPFEM的构建方法.探讨了DPFEM的系统设计目标,系统平台,软件配置以及系统运作机制.     

钢结构随机有限元动力分析

钢结构在应用一段时间后,物理参数和几何参数的变化将导致结构参数发生某些不确定性的改变, 这将会影响结构的力学特性.从此问题出发,通过一个算例详细阐述了用摄动随机有限元法解决此类问题的实现过程.     

门式刚架端板连接节点在加劲肋作用下的性能研究

目前国内端板连接计算方面还没有设计规范,理论方面仍在探讨研究中。我国现行规程关于端板连接承载力的设计计算方法中还没有考虑端板加劲肋对节点承载力的影响。本文使用通用有限元软件ANSYS 10.0综合考虑了三重非线性的影响,同时考虑了螺栓预拉力的影响,对考虑端板厚度、端板加劲肋的设置、螺栓直径、摩擦系数等参数不同的3个系列28个门式刚架梁柱节点试件进行了有限元数值模拟,对连接节点的性能进行了分析研究,提出了设计建议以供参考。     

Central bank interventions and jumps in double long memory models of daily exchange rates

In this paper, we estimate ARFIMA–FIGARCH models for the major exchange rates (against the US dollar) which have been subject to direct central bank interventions in the last decades. We show that the normality assumption is not adequate due to the occurrence of volatility outliers and its rejection is related to these interventions. Consequently, we rely on a normal mixture distribution that allows for endogenously determined jumps in the process governing the exchange rate dynamics. This distribution performs rather well and is found to be important for the estimation of the persistence of volatility shocks. Introducing a time-varying jump probability associated to central bank interventions, we find that the central bank interventions, conducted in either a coordinated or unilateral way, induce a jump in the process and tend to increase exchange rate volatility.