A hybrid parallel genetic algorithm for yard crane scheduling

This paper aims at postulating a novel strategy in terms of yard crane scheduling. In this study, a dynamic scheduling model using objective programming for yard cranes is initially developed based on rolling-horizon approach. To resolve the NP-complete problem regarding the yard crane scheduling, a hybrid algorithm, which employs heuristic rules and parallel genetic algorithm (PGA), is then employed. Then a simulation model is developed for evaluating this approach. Finally, numerical experiments on a specific container terminal yard are used for system illustration. Computational results suggest that the proposed method is able to solve the problem efficiently.     

An LP-based tabu search for batch scheduling in a cutting process with finite buffers

This paper addresses a cutting stock problem under typical resource constraints that arise when working centres with nesting capabilities are associated with automatic feeders/stackers. The critical resource is the number of buffers available to host the batches built up by the centre. To cope with it, pattern and batch sequencing problems must be addressed simultaneously. A tabu-search algorithm exploring batch output sequences is proposed. The algorithm never opens more stacks than buffers, respects batch compatibility/precedence constraints, and keeps the maximum order spread under control. To demonstrate its effectiveness and efficiency, a computational study was set up, solving 920 test problems derived from the literature. The study enabled a proper tuning of the method and offered encouraging results: in 228 cases an optimum was found; in nearly all, the gap from the optimum was below 1%. Computation times range from fractions of seconds to a couple of minutes in the worst cases. Compared to existing methods, the algorithm provides on average the same solution quality, with the advantage of solving a problem which is more general and hence closer to application. The paper includes a discussion on the method extensions required to deal with asynchronous stacking and heterogeneous batches.     

On the short-time behavior of the implied volatility for jump-diffusion models with stochastic volatility

In this paper we use Malliavin calculus techniques to obtain an expression for the short-time behavior of the at-the-money implied volatility skew for a generalization of the Bates model, where the volatility does not need to be a diffusion or a Markov process, as the examples in Sect. 7 show. This expression depends on the derivative of the volatility in the sense of Malliavin calculus. E. Alòs’ research is supported by grants MEC FEDER MTM 2006 06427 and SEJ2006-13537. J.A. León’s research is partially supported by the CONACyT grant 45684-F. J. Vives’ research is supported by grant MEC FEDER MTM 2006 06427.     

A direct comparison of physical block occupancy versus timed block occupancy in train timetabling formulations

Two fundamental mathematical formulations for railway timetabling are compared on a common set of sample problems, representing both multiple track high density services in Europe and single track bidirectional operations in North America. One formulation, ACP, enforces against conflicts by constraining time intervals between trains, while the other formulation, RCHF, monitors physical occupation of controlled track segments. The results demonstrate that both ACP and RCHF return comparable solutions in the aggregate, with some significant differences in select instances, and a pattern of significant differences in performance and constraint enforcement overall.     

A Formal Study of Distributed Meeting Scheduling

Automating routine organizational tasks, such as meeting scheduling, requires a careful balance between the individual (respecting his or her privacy and personal preferences) and the organization (making efficient use of time and other resources). We argue that meeting scheduling is an inherently distributed process, and that negotiating over meetings can be viewed as a distributed search process. Keeping the process tractable requires introducing heuristics to guide distributed schedulers' decisions about what information to exchange and whether or not to propose the same tentative time for several meetings. While we have intuitions about how such heuristics could affect scheduling performance and efficiency, verifying these intuitions requires a more formal model of the meeting schedule problem and process. We present our preliminary work toward this goal, as well as experimental results that validate some of the predictions of our formal model. We also investigate scheduling in overconstrained situations, namely, scheduling of high priority meetings at short notice, which requires cancellation and rescheduling of previously scheduled meetings. Our model provides a springboard into deeper investigations of important issues in distributed artificial intelligence as well, and we outline our ongoing work in this direction.     

运输车辆调度优化的研究和实现

通过对车辆调度问题进行数学分析,提出了简单实用的车辆调度算法,为实现计算机半智能执行调度任务,设计了车辆的分配及优化方案。对物流配送企业实现计算机配送调度,降低成本和提高物流经营管理水平具有一定的参考价值。     

跨区域能源调度与经济增长关系研究--来自西气东输工程的证据

自2002年以来,中国陆续实施了西气东输工程一、二、三线工程的建设,这可以看作是国家在跨区域能源调度方面进行的一次自然实验。本文构造1999～2011年西气东输工程沿线经过城市和未经过城市的面板数据,采用双重差分法对西气东输工程的实施影响沿线地区经济增长的效果进行验证。结果表明,这一工程的实施显著地促进了沿线城市的经济增长,相比未经过的城市,西气东输工程将沿线城市的经济增长速度提高了约2畅1个百分点。国家在调节区域均衡发展时,需要进一步挖掘重大跨区域资源调度项目的经济辐射带动作用。     

港口物流系统的调度仿真研究

港口调度是港口生产组织的关键问题,调度方案的好坏直接决定了港口作业的效率,本文首先对集装箱港口物流系统的结构、控制需求等进行了分析,然后提出了应用AutoModV10.0仿真软件,构建具有离散性、随机性特征的港口物流系统模型的方法。     

带偏射补偿机制的Birkhoff-von-Neumann交换机方案及其性能分析

Birkhoff-von-Neumann（BvN）交换机具有较低的执行复杂度和较高的吞吐量,但无法在业务突发的环境下提供性能保证。为此,提出一种带偏射的BvN（D-BvN）交换机制来增强交换机性能。D-BvN交换机通过平均业务矩阵的BvN分解,为每个虚电路（VC）提供均值带宽保证,同时通过偏射来处理业务突发。其主要思想是利用处于空闲状态的VC的闲置容量处理处于溢出状态的VC的溢出业务。具体地,偏射机制利用空闲VC的闲置容量完成两件事情：一是把溢出业务偏射到其他VC,二是给偏射业务提供到达目的端口的带宽。分析和仿真结果表明,所提方法不仅可以获得接近100%的输入负载吞吐量,而且具有较低的包乱序概率和较小的业务包延时。     

一种多信道的分簇式短波令牌协议

传统的短波令牌协议（HFTP）调度方式单一,在没有数据传送时,信道资源会被各节点间的令牌传递所占用,且令牌在通信质量较差时易丢失。基于此,提出一种多信道的分簇式短波令牌协议（CHFTP）,通过以通信质量评估为标准的分簇算法和基于预约的动态令牌调度,减小了令牌丢失的概率和令牌传递、处理的开销,并给出了仿真分析。仿真结果表明,该协议的端到端平均时延和网络吞吐量明显优于短波令牌协议,CHFTP的平均时延最多可减少75%,网络吞吐量最多可增加66.7%,适合在短波通信网络中使用。