Constructive heuristics for the Mixed Capacity Arc Routing Problem under Time Restrictions with Intermediate Facilities

The Mixed Capacity Arc Routing Problem under Time Restrictions with Intermediate Facilities (MCARPTIF) is an extension of the Arc Routing Problem under Capacity and Length Restrictions with Intermediate Facilities (CLARPIF) with application in municipal waste collection. This paper evaluates four constructive heuristics capable of computing feasible solutions for the MCARPTIF with a primary objective to either minimise total cost or to minimise the fleet size. The heuristics were adapted from Path-Scanning and Improved-Merge for the Mixed Capacitated Arc Routing Problem, and compared against two Route-First-Cluster-Second heuristics for the MCARPTIF. The objective was to identify the best performing heuristic for application purposes. In practice, the CARP is often solved for real-time or near real-time decision support. Computational time required by the heuristics was thus also evaluated. Identifying the best heuristic proved difficult due to a lack of realistic MCARPTIF benchmark sets, with the two CLARPIF sets predominantly solved in the literature not resembling actual waste collection instances. Route-First-Cluster-Second heuristics, linked with a new vehicle reduction heuristic performed the worst on the two CLARPIF sets, yet performed the best on new waste collection sets taken from the literature and introduced in this paper. Improved-Merge performed the best on two existing CLARPIF sets and on a realistic set with Intermediate-Facilities incident with the vehicle depot, but struggled on all other sets and in minimising fleet size. Path-Scanning was the most robust heuristic, performing reasonably well on all benchmark sets and both objectives. Results further show that due to the high computational time of one of the Route-First-Cluster-Second heuristics, which was only exposed on realistically sized sets, the slightly worse version is the best alternative when real-time support is required for waste collection applications.     

Undecidable properties of flat term rewrite systems

Reachability, joinability and confluence properties are known to be undecidable for flat term rewrite systems (TRS). We give shorter and conceptually simpler proofs of these results. We also prove undecidability of weak normalization and unique normalization properties for flat TRS. The first author was supported by Spanish Ministry of Education and Science by the FORMALISM project (TIN2007-66523) and by the LOGICTOOLS-2 project (TIN2007-68093-C02-01). The second author was supported by Spanish Ministry of Education and Science by the FORMALISM project (TIN2007-66523).     

经济全球化对发展中国家主权限制问题分析

经济全球化给发展中国家主权带来的限制体现在国家主权的约束与让渡两个方面.面对国家主权的限制.发展中国家有主动和被动两种反应,有机遇与挑战两种后果.发展中国家应采取措施,积极应对.     

英语专业学生作文中动名搭配错误分析

搭配一直是英语学习的重点和难点。针对国内对于英语专业学生的搭配研究较少的情况,本文对英语专业二年级学生的试卷命题作文中所有的动名搭配进行了抽样分析,得出了一些结论:诸如动词搭配是英语学习的难点,学习者过度依赖和使用非词化词,依赖母语的思维模式和搭配习惯等;最后本文提出以搭配为中心的词汇教学。     

双向搜索多约束路由启发式计算方法

为提高大型通信网络中搜索满足多约束条件路由的速度,提出一种双向搜索路由的计算方法.首先从源和目的节点同时出发,计算到达各中间节点的可达路径.然后在各可达路径中进行路径的筛选.可达路径是采用邻接矩阵变换方式获得的,筛选路径是根据非线性开销函数,采用启发方式择优选取.当两方向搜索的节点数累计达到n-2后,对接合并两方向到达中间节点的路径,从中再选择最佳路径作为路由输出.通过算例详细介绍了可达路径计算及启发式选优方法.阐述了算法的正确性及特点,分析了最大时间杂性.通过仿真实验评估,不仅更进一步验证了新算法的正确性,而且表明新算法在搜索路由速度上要优于其他算法.     

柱形光子晶体波导中偏振光的传输模式和禁带特征

利用光波在一维有限周期柱型光子晶体波导中径向受限的条件,推导出TE波和TM波2种偏振光在一维有限周期柱型光子晶体波导中各个传输模式满足的关系式。研究了各个传输模式的特征,计算出TE波和TM波传输各模式的禁带随周期数、模式量子数、圆柱半径以及入射角的变化规律,得出了一维有限周期柱型光子晶体波导中TE波和TM波各传输模式带隙的结构。     

Integrated assembly line balancing with resource restrictions

This paper documents a study carried out on the problem of designing an integrated assembly line when many workers with a variety of skills are employed. This study addresses the problem of selecting multi-functional workers with different salaries to match their skills and of assigning tasks to work stations when there are precedence restrictions among the tasks. The objective of this study is to minimise the total annual work station costs and the annual salary of the assigned workers within a predetermined cycle time. A mixed integer linear program is developed with a genetic algorithm in order to address the problem of resource restrictions related to integrated assembly line balancing. Numerical examples demonstrate the efficiency of the developed genetic algorithm.     

一维固-液平板声子晶体中弹性波的模式和带隙

利用一维固-液结构平板声子晶体中弹性波横向受限的条件,推导出弹性波在一维固-液结构平板声子晶体中各个模式满足的关系式,利用这个关系式并结合转移矩阵计算出弹性波各模式的带隙随模式量子数和平板厚度以及入射角的变化规律。得出了一些不同于一维固-液结构非受限声子晶体带隙的新特征。     

Building phonotactic knowledge in bilinguals: Role of early exposure.

Timing and amount of exposure to a 2nd language in the acquisition of phonotactic restrictions was examined in 4 experiments. In Experiments 1 and 2, 10-month-old monolingual and bilingual Catalan-Spanish infants were presented with nonwords that were phonotactically legal or illegal in Catalan and phonotactically illegal in Spanish. Differences between the 4 groups of infants were obtained as a function of language dominance. In Experiments 3 and 4, adult Spanish-Catalan bilinguals were compared with the same materials. Catalan-dominant bilinguals were more accurate than Spanish-dominant bilinguals in their perception of legal sequences; however, they were not more accurate with illegal sequences. The findings suggest a complex correlation between the pattern of preference and the amount and timing of exposure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

弹目交会参数对超宽带近炸引信设计的约束分析

UWB(超宽带)近炸引信是一种新体制近炸引信,现有文献对系统的分析设计主要是针对器件的设计,有关引信战术指标的优化设计还是空白.在阐明了UWB(超宽带)近炸引信的测距原理和作用过程的基础上,首次通过对某种弹目交会条件的分析,在一假定的初始条件下,进行了数值仿真分析,得出系统探测距离与天线的波束倾角之间的关系,为系统整体设计优化指出了方向,对系统的具体战术指标确定提供了理论依据.