遗传算法在轨道交通换乘路径求解问题上的应用

文章建立了轨道交通路网简化模型,将遗传算法引入轨道交通换乘路径的求解过程,结合上海市轨道交通运营线路实例进行模拟仿真,所得结果表明该算法的可行性和有效性。     

最短路径的求解算法

文章提出了一种求最短路径的算法,该算法能高效地求出一个顶点到其它各顶点的所有最短路径。用C语言设计了相应的程序验证了此算法。     

基于AR规则的全路径测试数据自动生成方法

基于全路径的研究现正处于起步阶段,提出了一种全新的NRPS算法（不重复路径搜索算法）和AR规则来对程序的源文件进行静态分析,生成有向无负权图,进而得到不重复路径集;并结合粒子群优化算法最终生成最优测试用例。实验表明,该方法具有可行性。     

一种新的型腔铣削刀轨生成算法

在对型腔外轮廓和岛屿轮廓分别考虑的基础上,对各封闭环路进行简化,提出了一种新的干涉标志量递推规则,实现了多种等距环交点情况的统一处理,降低了算法复杂度.文中给出了由该算法生成的带岛屿型腔刀位轨迹的实现步骤及计算实例.测试表明,该算法计算速度快,稳定性好.     

传统造物智慧启迪现代产品创新设计的路径探究

目的 为推动中华优秀传统文化在当代生活中的创造性转化、发展搭建桥梁与铺设路径。方法 通过对中国椅与明式圈椅、“你我同舟”烛台与楔钉榫、鼎壶与唐代戒盈杯、多功能休.眠平台与清代拔步床等设计案例的比较研究,并结合对明式坐具当代化设计与家用汽车遮阳产品设计实践的归纳总结,提炼出传统造物智慧启迪现代产品创新设计的四条路径,即形态创新的启迪、结构创新的启迪、功能创新的启迪、内在意义创新的启迪。结论 中国传统造物智慧博大精深,启迪现代产品创新设计的路径也应坚持百花齐放、百家争鸣。叩其两端而执其中,持续探究与规划启迪路径,实现“条条大路通罗马”与“古为今用”,进而让更多的传统造物智慧在现代产品创新设计实践中更好地“再现”与“传承”。     

基于子结构的内力约束连续体拓扑优化

通过拓扑优化可以得到传力路径,不同传力路径对应不同内力载荷。如果将内力载荷作为目标或约束进行拓扑优化,可以得到满足不同需求的传力路径,为拓扑优化的发展提供新思路和新方法。为了得到不同内力载荷需求的传力路径,基于子结构法将结构分开使内力暴露出来。以结构质量最小为目标,以内力为约束建立拓扑优化模型,基于独立、连续、映射( independent, continuous, mapping, ICM)方法和单位载荷法将内力显式化,通过累加获得需要控制的传力路径上的内力,通过迭代调整2个路径上的内力使其比值达到一个稳定的值,从而获得满足内力约束的传力路径。算例表明：不同的内力约束可以得到不同的传力路径。     

正规网格等值线的虚路径扫描算法

等值线图在工程分析和计算领域有着广泛的应用。该文以正规化的采样数据为研究对象,提出了一种全新的虚路径扫描算法。算法在数据网格基础之上构筑一虚拟的路径网格,利用路径网格上的线段（虚路径）来记录等值点的追踪路径信息。所有等值线的虚路径的捕获只需通过一次性扫描即可完成,不仅提高了追踪效率,而且避免了以往等值线追踪算法初始点选择困难、网格出口边判断复杂等一系列问题。算法的另一优点是追踪结果的精度是可控的,取决于等值点如何取值。该算法在土地定级中的作用分等值线图绘制中得到很好的应用。虚路径的思想同样适用于非正规的采样数据。     

On a compressed elastic–plastic column optimized for post-buckling behaviour

A model of a column is proposed in order to analyse the post-buckling behaviour of a structural element in the elastic–plastic deformation range. The ideal two point I-section applied here simplifies the deformation analysis, that is, the problem of development of plastic zones in a section is eliminated, but still gives the possibility for qualitative analysis and optimization of the post-critical equilibrium paths. The coefficients of linear or parabolic variability of thickness of the flanges and their distance (web width) are accepted as model parameters and hence could be used for design variables in the optimization procedure. Moreover, the stiffness of an additional elastic support of the free end of the beam is also included as a parameter or design variable. A material model is employed with non-linear asymptotic isotropic hardening without the Bauschinger effect. Change of the tangent modulus is continuous and smooth during the transition from the elastic to plastic deformation range. The main goal of the analysis is to determine the values of the design variables for which the post-critical equilibrium paths are stable at least in the specified range of a generalized displacement. The constraints for the constant volume of the flanges and web material are applied. The inequality constraints are imposed on the flange thickness and web width. Various formulations of the optimization problem are proposed for all types of non-linear behaviour, including elastic or plastic buckling and elastic or elastic–plastic post-buckling deformation.     

On ACK filtering on a slow reverse channel

Acknowledgement (ACK) filtering has been proposed as a technique to alleviate the congestion at the input of a slow channel located on the reverse path of a TCP connection. Old ACKs waiting at the input of the slow channel are erased when new ACKs are to be queued. In the literature the case of one‐ACK per connection at a time has been studied. In this paper we show that this is too aggressive for short transfers where ACKs arrive in bursts due to the slow start phase, and where the TCP source needs to receive the maximum number of ACKs to increase fast its window. We study first static filtering where a certain ACK queue length is allowed. We show analytically how this length needs to be chosen. We present then some algorithms that adapt the filtering of ACKs as a function of the slow channel utilization rather than the ACK queue length. These algorithms provide a good compromise between reducing the ACK queueing delay and passing a large number of ACKs that guarantee a fast window increase. Copyright © 2003 John Wiley & Sons, Ltd.     

External matrix multiplication and all-pairs shortest path

Algorithms are presented for external matrix multiplication and for all-pairs shortest path computation. In comparison with earlier algorithms, the amount of I/O is reduced by a constant factor. The all-pairs shortest path algorithm even performs fewer internal operations, making the algorithm practically interesting.