基于SolidWorks的直齿圆柱齿轮建模方法与有限元分析

目的:使用Solid Works软件进行齿轮应力分析。方法:采用CAXA、Solid Works联合建模及Solid Works中公式曲线的方法进行齿轮建模。结果:在正确建模的基础上完成齿轮应力分析。结论:建模方法简单且较精确,能够满足齿轮应力分析的要求。     

Moment estimation in discrete shifting level model applied to fast array‐CGH segmentation

We develop a mathematical theory needed for moment estimation of the parameters in a general shifting level process (SLP) treating, in particular, the finite state space case geometric finite normal (GFN) SLP. For the SLP, we give expressions for the moment estimators together with asymptotic (co)variances, following, completing, and correcting Cline (Journal of Applied Probability 20, 1983, 322–337); formulae are then made more explicit for the GFN‐SLP. To illustrate the potential uses, we then apply the moment estimation method to a GFN‐SLP model of array comparative genomic hybridization data. We obtain encouraging results in the sense that a segmentation based on the estimated parameters turns out to be faster than with other currently available methods, while being comparable in terms of sensitivity and specificity.     

建筑结构中有限元分析技术的教学应用研究

采用有限元分析技术模拟分析钢筋混凝土简支梁的受力特性,可以使学生更清楚地理解梁的破坏过程,既丰富了教学手段,又激发了学生学习的兴趣。     

《有限元法》课程的典型案例教学法的研究与实践

现提出典型案例的《有限元法》课程教学改革方法,取代过去以理论教学为主的方法。以常见的齿轮零件作为应用例子进行讲解,极大的提高了学生学习兴趣和动力,取得了很好的效果。     

High-order accurate implicit finite difference method for evaluating American options

A numerical method is presented for valuing vanilla American options on a single asset that is up to fourth-order accurate in the log of the asset price, and second-order accurate in time. The method overcomes the standard difficulty encountered in developing high-order accurate finite difference schemes for valuing American options; that is, the lack of smoothness in the option price at the critical boundary. This is done by making special corrections to the right-hand side of the differnce equations near the boundary, so they retain their level of accuracy. These corrections are easily evaluated using estimates of the boundary location and jump in the gamma that occurs there, such as those developed by Carr and Eaguet. Results of numerical experiments are presented comparing the method with more standard finite difference methods.     

A note on robust testing by indexing the parameter space

1. Introduction

A preliminary test is sometimes performed to obtain a simple model with few parameters. This should ostensibly result in a better performance in the subsequent treatment of the observations. For obvious reasons such a procedure is questionable. It is felt that one should keep to the original a priori model with the original parameter vector θ. In this note a third method is proposed. Adhere to original parameters θ, but concentrate attention on an index φ(θ) which sums up some essential features of the model. (This principle has been advocated by Goldstein (1981).)     

基于UG的闸阀CAE

利用UG软件强大的CAD/CAE功能进行闸阀的建模、装配、关键部分的运动仿真及阀体的有限元分析,对阀体尺寸和结构进行优化。建模所得的实体模型直接用于运动仿真分析和有限元分析,缩短了设计所需的时间,减少了软件间的数据交换。闸阀从建模、装配到运动仿真,再到优化设计,将在同一个软件中进行,可以减少物理样机的制造、试验等过程,提高工作效率,缩短产品的设计周期。     

基于非线性规划和有限元法的悬臂式桁架优化设计

为了对悬臂式桁架结构进行改进与优化,提出了一种更为简单可行的非线性规划模型。首先,在充分分析悬臂式桁架使用要求的基础上,创新性地将悬臂端节点挠度和结构的可靠性分别视为目标函数和限制条件,并通过静力学分析确定了目标函数和限制条件的具体表达式。然后,利用Python语言编程对优化方案进行求解,发现在给定的限制条件下,当桁架的总长为4 m、总高为2.6 m且杆件的横截面积为1 400 mm~2时,悬臂端节点的挠度最小。最后,利用ABAQUS软件并根据有限元法来判断优化方案的合理性。有限元法的计算结果表明:得出的优化方案是较为准确合理的,且适当减少桁架的总长并增大桁架的总高和杆件的横截面积,可以降低悬臂端节点的挠度。因此,基于非线性规划模型提出的目标函数和限制条件为其他类型桁架结构的优化设计提供了新思路。     

有限元分析系统在结构计算中的比较及展望

工程领域内常用的数值模拟方法主要是有限单元法。利用有限元分析程序可以得到满足工程要求的数值解．解决工程中的结构分析问题，缩短设计周期，降低设计成本。主要介绍ANSYS、ANSYS／LS-DYNA及ADINA三种有限元分析系统的技术特点、功能和应用领域，同时对国际上有限元分析系统在结构计算中的发展方向进行分析．并对国内有限元分析系统的发展前景进行了展望，并提出努力方向。     

MAXIMUM ENTROPY REVISITED

Maximum entropy or minumum information distributions have their flexibilities severely curtailed if R or R₊ is the domain and α is imposed as a Lebesgue measure. Tremendous flexibility is gained by removing these restrictions.