某大客车车架结构模态分析

为计算某大客车车架骨架模态,分析设计的合理性,考察各部件间的共振特性,用HyperWorks对车架有限元模型进行前、后处理,抽取三维模型的中面,在中面上划分网格,采用SHELL单元为基本单元,建立各零部件的有限元模型.应用OptiStruct求解得到车身骨架前6阶的模态及振型描述.从仿真分析可知,客车车身固有频率能避开...     

基于ObjectARX的轻型木桁架节点模拟软件

为克服轻型木桁架设计过程中计算工作量大、手算难以实现的问题,利用ObjectARX编写豪式桁架和芬克式桁架的任意外形建模及计算模型自动生成程序.该程序采用规范推荐的节点模拟法体现齿板连接而产生的节点半刚性特征：用多根模拟弦杆、腹杆和若干分节点构成模拟节点;所有杆件数据通过Xdata扩展数据形式集成在杆件单元中,便于后续程序进行内力计算、简化轻型木桁架的工程设计计算过程.经豪式桁架试算实例,验证该程序生成的模型满足规范要求,易于调整,数据结构良好,且能体现齿板连接引起的刚度修正结果.     

Test frame updating in CPM testing of Prolog programs

Category Partition Method (CPM) is a general approach to specification-based program testing, where test frame reduction and refinement are two important issues. Test frame reduction is necessary since too many test frames may be produced, and test frame refinement is important since during CPM testing new information about test frame generation may be achieved and considered incrementally. Besides the information provided by testers or users, implementation related knowledge offers alternative information for reducing and refining CPM test frames. This paper explores the idea by proposing a call patterns semantics based test frame updating method for Prolog programs, in which a call patterns analysis is used to collect information about the way in which procedures are used in a program. The updated test frames will be represented as constraints. The effect of our test frame updating is two-fold. On one hand, it removes “uncared” data from the original set of test frames; on the other hand, it refines the test frames to which we should pay more attention. The first effect makes the input domain on which a procedure must be tested a subset of the procedure’s input domain, and the latter makes testers stand more chance to find out the faults that are more likely to show their presence in the use of the program under consideration. Our test frame updating method preserves the effectiveness of CPM testing with respect to the detection of faults we care. The test case generation from the updated set of test frames is also discussed. In order to show the applicability of our method an approximation call patterns semantics is proposed, and the test frame updating on the semantics is illustrated by an example.

新闻制作网网络架构应用分析

以一个将所有有卡编辑工作站全部采用纯千兆以太网方式接入,通过NAShead访问SAN网络存储的新闻制作网实例,分析这类网络结构的可行性与在实际应用中所遇见的问题和解决的过程,更进一步了解这种网络结构的特点和适用范围。     

安徽省地震会商系统软件界面设计研究

基于ARCGis9.2的安徽省地震会商系统不仅需要强大的技术功能,还需要友好和一目了然的界面,这样不仅让会商报告者思路清晰,也能使会商观众更加清晰了解地震预报会商内容,从而为决策者更好应对不同地点和不同大小的地震发生可能性做出科学的决策;引入flash8作为软件系统的界面,用flash调用各个模块,无论从界面和功能上都较好的解决了这一问题。     

三框架电容式硅微机械陀螺动力学分析

为了解决双框架陀螺在加工中不可避免的误差,提出了三框架电容式微机械陀螺系统。该系统由3个框架(即3个质量块)组成。采用静电差分驱动方式,梳状叉指电容,多个柔性杆设计使得该结构从理论分析和加工误差上解决了耦合现象。同时,通过提高中间框架的质量,使得陀螺的灵敏度大大提高。介绍了该三框架电容式微机械陀螺仪的工作原理,给出了所设计陀螺动力学方程的详尽推导和MAT-LAB仿真分析。     

基于因果的自适应双阈值镜头边界检测算法

将因果检测法与双阈值法相结合,提出了一种基于因果的自适应双阈值镜头边界检测算法.首先,利用相邻两帧之间的帧间差异值对突变和渐变进行预检;然后,加入渐变检测容忍度、边缘和非相邻帧间差异值等信息,对初检结果进行复检,排除闪光灯、剧烈物体运动、淡入、淡出以及溶解等造成的误检和漏检,以提高整体检测效果.实验结果表明,与传统的双阈值镜头检测方法相比,本方法可获得更好的检测性能.     

High‐pixel‐rate grating‐light‐valve laser projector

Abstract— A high‐pixel‐rate, high‐contrast (30,000:1) wide‐color‐gamut grating‐light‐valve laser projector is reported. A new optical engine enabling high‐frame‐rate (240 Hz) scan projection is employed. Panoramic wide‐angle‐scan projection with a 64:9 aspect ratio was also developed. Speckle noise is eliminated using a simple but highly efficient technique. The optical throughput efficiency of the grating‐light‐valve laser projector is reviewed.     

Geometric nonlinear effects on the planar dynamics of a pivoted flexible beam encountering a point-surface impact

Flexible-body modeling with geometric nonlinearities remains a hot topic of research by applications in multibody system dynamics undergoing large overall motions. However, the geometric nonlinear effects on the impact dynamics of flexible multibody systems have attracted significantly less attention. In this paper, a point-surface impact problem between a rigid ball and a pivoted flexible beam is investigated. The Hertzian contact law is used to describe the impact process, and the dynamic equations are formulated in the floating frame of reference using the assumed mode method. The two important geometric nonlinear effects of the flexible beam are taken into account, i.e., the longitudinal foreshortening effect due to the transverse deformation, and the stress stiffness effect due to the axial force. The simulation results show that good consistency can be obtained with the nonlinear finite element program ABAQUS/Explicit if proper geometric nonlinearities are included in the floating frame formulation. Specifically, only the foreshortening effect should be considered in a pure transverse impact for efficiency, while the stress stiffness effect should be further considered in an oblique case with much more computational effort. It also implies that the geometric nonlinear effects should be considered properly in the impact dynamic analysis of more general flexible multibody systems.     

构件化信息系统开发方法研究

首先由传统的信息系统开发方式的缺陷引出了软件构件化概念,然后对构件的属性、构件开发标准规范、信息系统构件化开发方法进行了介绍,最后给出了一种信息系统构件化开发框架探讨信息系统的构件化开发方法。