基于SolidWorks Simulation的装配式桥式电动升降平台附墙架设计与分析

以装配式桥式电动升降平台附墙架结构为研究对象，利用Soildworks软件，进行结构的设计和有限元模型的建立。通过对不同附着结构形式的强度、刚度及稳定性的分析，选取了较优的结构形式，研究了附墙架组成杆件截面尺寸、附墙架长度对其各项性能的影响。研究结果表明，对于附墙架结构形式，采用单侧两杆式附墙架结构形式较为经济；附墙架拉杆截面尺寸为40 mm时，各构配件性能最优；附墙架拉杆长度2 500 mm是附墙架应力、变形位移值的拐点，为保证使用的安全性，长度应小于2 500 mm。     

铸造起重机应力仿真与疲劳寿命评估

采用有限元分析法与现场测试相结合的方法来得到主梁的应力情况。从而得出在外主梁下盖板跨中位置的主应力与外主梁主腹板两端剪应力最大,这几处附近的焊缝部位存在着应力集中现象,需结合现场采集的数据对这几处做疲劳寿命评估。结果得出虽然跨中焊缝处应力最大,但其寿命仍有46年,此铸造起重机仍然安全。     

Time Changes for Lévy Processes

The goal of this paper is to consider pure jump Lévy processes of finite variation with an infinite arrival rate of jumps as models for the logarithm of asset prices. These processes may be written as time-changed Brownian motion. We exhibit the explicit time change for each of a wide class of Lévy processes and show that the time change is a weighted price move measure of time. Additionally, we present a number of Lévy processes that are analytically tractable, in their characteristic functions and Lévy densities, and hence are relevant for option pricing.     

小车河铁路隧道边坡的加固方案分析

边坡稳定是一个非常复杂的问题,文章采用有限元分析法(运用有限元软件ANSYS),通过对毗邻小车河铁路隧道的房产开发项目的基坑开挖过程进行数值模拟分析,从理论上得出了该工程对既有铁路隧道影响程度,同时提出相应的加固处理建议。     

双线性有限元Monte Carlo方法

本文构造了矩形有限元的概率算法,应用这种方法可以直接求出有限元解在一个或少数几个网格点的近似值。     

基于DSP技术的RFID读写器设计

论述了基于DSP技术的RFID读写器设计方法。在描述RFID系统组成的基础上，给出了读写器的软硬件设计流程。重点阐述了DSP对接收信号的软件处理以及反冲撞功能的实现方法。该读写器已应用于开放式门禁系统中，实际应用结果表明其性能良好。     

A Path Construction for the Virtual Waiting Time of an M/G/1 Queue

Consider the M/G/1 queue, the finite dam M/G/1 with capacity T, and the impatient customer M/G/1 model, where customers become lost customers if their waiting time exceeds τ. In this note we prove that for all three models and each xe(0, r) the distribution of the number of downcrossings of the virtual waiting time process with level x during a busy cycle is identical. This implies the weaker statement that on [0, T) the distribution functions of the steady state distributions of the amount of unprocessed work (virtual waiting time) are proportional. A number of applications is given.     

On Social Statement Spaces

In this fundamental draft we shall introduce the concept of social propositional spaces as a general notion of social science and in particular language, logic and methodology. This should help us bridge an old gap between extension and cognition, or said in more specific words, between space as conceived in mathematics or physics and space as is brought in by social location, by the meaning of predicates, their explanation and logic. ¹ We shall not rely on the idea of factor analysis where some “main components” are fit into the data. Because the notion of euclidean normalization and orthogonality, in this context, is a bit artificial. We first show how combinatorial manifolds of statements can be represented in finite vector spaces over the Galois field F₂. This space which we denote as logic statement space can be spanned by generators of alternating codes. In this way the old concepts of truth tables and interaction attributes can be linked to informatics and in particular code theory and geometry. Extending the logic statement space onto a real vector space by mapping units of the finite rings onto units of the real rings we obtain logistic statement spaces. It turns out that vectors in logistic statement spaces represent cross-tables of logits connected with logistic regression analysis. As a completion of the theory we show that the logit is the first derivative of entropy with respect to probability.     

Fiscal policy and private consumption behaviour: The Spanish case

In this article we analyse whether the Ricardian equivalence hypothesis is a valid approximation for Spains economic reality or whether there exist deviations from that situation which would be more in line with the conventional Keynesian perspective of the effects of debt on private consumption-savings decisions.Our aim is to contribute to the rather sparse empirical literature on the subject for the Spanish case. The analysis is based on annual aggregate data for Spain covering the years 1955 to 2000, and uses both the structural and the Euler equation approaches to test the neutrality proposition, and is thus to be considered as a generalization of foregoing work on the Spanish economy.The findings indicate that support for Ricardian equivalence is mixed, while we also find very little support for the Keynesian specification of consumption and fiscal policy.First revision received: March 2003 / Final version received: October 2003The authors wish to thank M. Ferré, J.M. González-Páramo, A. Marchante, P. Meguire, F. Pedraja, J.L. Raymond, J. Salinas and two anonymous referees for their helpful comments and suggestions on this paper. We also thank the participants in the V Encuentro de Economía Aplicada (Oviedo, Spain, June 2002) and the XVII Simposio de Análisis Económico (Salamanca, Spain, December 2002) for their comments. Any remaining defects are our responsibility. We also are grateful to the Institute for Fiscal Studies of Spain (Ministerio de Hacienda, Secretaría de Estado de Hacienda) for its financial support.     

冲击电压下特高压支柱绝缘子表面电场研究

特高压输变电工程对支柱绝缘子提出了更高的技术要求,运行中支柱绝缘子会因雷击发生污闪,而支柱绝缘子的电场、电位分布和闪络现象存在一定关系。为研究特高压支柱绝缘子表面电场分布特性,建立了1 100kV支柱绝缘子的有限元计算模型。理论分析与仿真结果表明,雷电冲击电压作用下支柱绝缘子表面电场分布随时间变化的曲线在波形上与激励源雷电波的波形相似,第一对和最后一对大小伞的电场强度较大,中间大小伞的电场强度较小,最大场强点位于金属电极下端的绝缘护套表面。