改进节约蚁群算法求解物流配送车辆路径问题

针对节约蚁群算法在求解车辆路径问题易陷入局部极值的不足,提出一种基于连接表扰动策略和吸引力因子局部搜索的改进节约蚁群算法.该算法在陷入局部最优后,引入连接表扰动策略以帮助算法跳出局部最优,该策略在每只蚂蚁进行解构建之前,随机禁忌若干条吸引力因子较大的边以增加算法的勘探能力;同时采用吸引力因子局部搜索优化每只蚂蚁的解,该局部搜索利用吸引力因子引导局部搜索.实验结果表明,改进节约蚁群算法求解车辆路径问题时优于原有节约蚁群算法以及多种已有算法.     

基于SPN的无线闭塞中心切换过程中的故障分析

分析在RBC2(接收无线闭塞中心(RBC))不同时段故障工况下,对RBC切换的影响,选取形式化描述语言随机Petri网(SPN),分别建立RBC2在不同时段故障下RBC的切换模型,采用SPN数学建模,通过SPNP6.0分析RBC故障对切换的影响以及对行车安全和行车效率等方面的影响.分析结果可使人们对实际情况中RBC切换有更真实的认识,并对设备的改进、协议的完善等有一定的借鉴意义.     

基于模拟退火-自适应布谷鸟算法的城市公交调度优化研究

为改善城市常规公交运营效率,提出基于模拟退火-自适应布谷鸟算法的公交调度优化模型.通过结合线路实际客流数据反映的客流特征,建立考虑公交公司和乘客双方利益的公交调度优化模型;改进布谷鸟算法固定步长并加入模拟退火算法退火操作,设计模拟退火-自适应布谷鸟算法,改善寻优过程中跳出局部最优解而全局寻优的能力;以福州125路公交线...     

使用分类和聚类提高搜索引擎的可用性

由于很多Web用户面对搜索引擎搜索出来的成千上万条结果记录没有耐心一页一页地翻找,搜索出来的内容就不能得到有效的利用.自动分类聚类技术将是搜索引擎进一步改善搜索效率的一个很重要的方面.介绍联合使用分类聚类技术来改善搜索结果的表示形式,提高搜索引擎的可用性.     

现状车载下旧桥承载力评定和可靠度有限元分析

采用三维体元,进行4座旧桥现状车载(大于设计车载的2 5倍)下的有限元分析,对其承载力进行评定。结果表明,4座旧桥中有1座桥必须拆除,2座桥需要适当加固,1座桥不需要加固。用随机有限元计算旧桥在现状车载下的剩余可靠度结果表明,精确的分析模型能挖掘桥梁的承载潜力。用PSAP计算可靠度指标的灵敏度发现,可靠度指标对混凝土弹性模量比活载更敏感。     

Network Decomposition and Maximum Independent Set Part Ⅱ：Application Research

According to the researches on theoretic basis in part I of the paper，the spanning tree algorithms solving the maximum independent set both in even network and in odd network have been developed in this part，part Ⅱ of the paper．The algorithms trans form first the general network into the pair sets network，and then decompose the pair sets network into a series of pair subsets by use of the characteristic of maximum flow passing through the pair sets network．As for the even network，the algorithm requires only one time of trans formation and decomposition，the maximum independent set can be gained without any iteration processes，and the time complexity of the algorithm is within the bound of O(｜V｜^3)．However，as for the odd network，the algorithm consists of two stages．In the first stage，the general odd network is transformed and decomposed into the pseudo-negative envelope graphs and generalized reverse pseudo-negative envelope graphs alternately distributed at first；then the algorithm turns to the second stage，searching for the negative envelope graphs within the pseudo-negative envelope graphs only．Each time as a negative envelope graphhas been found．renew the pair sets network by iteration at once．and then tum back to the first stage．So both stages form a circulation process up to the optimum．Two available methods，the adjusting search and the picking-off search are specially developed to deal with the problems resulted from the odd network．Both of them link up with each other harmoniously and are embedded together in the algorithm．Analysis and study indicate that the time complexity of this algorithm is within the bound of O(｜V｜^5)．     

Local Search Algorithm with Hybrid Neighborhood and Its Application to Job Shop Scheduling Problem

A new local search method with hybrid neighborhood for Job shop scheduling problem is developed. The proposed hybrid neighborhood is not only efficient in local search, but also can help overcome entrapments while search procedure get trapped at local optima and carry the search to areas of the feasible set with better prospect. New strategies used for breaking out of entrapments are presented and they are helpful for the procedure to improve local optima. A performance comparison of the proposed method with some best-performing algorithms on all 10-job, 10-machine benchmark problems and the other two problems generated by Fisher and Thompson ( ie. , FT6 and FT20) is made. The experiment results show the better optimal performance of the proposed algorithm.     

When it comes to container port efficiency,are all developing regions equal?

In this paper we carry out a container port performance analysis of the developing world between 2000 and 2010, using both parametric and nonparametric approaches. From a unique dataset – our sample covers 70 developing countries, 203 ports, and 1750 data points–, we examine the evolution and drivers of productivity and efficiency changes across developing regions. We show that productivity growth rates between 2000 and 2010 vary significantly and that this heterogeneity is explained by pure efficiency changes rather than scale efficiency of technological changes. Therefore, we carry out a detailed efficiency analysis to determine the drivers of port efficiency. Time series results show an upward trend for port efficiency in developing regions, as it increased from 51 percent in 2000 to 61 percent in 2010. Our analysis indicates that private sector participation, the reduction of corruption in the public sector, improvements in liner connectivity and the existence of multimodal links increase the level of port efficiency in developing regions.