Transport schemes for topology-transparent scheduling

Transport protocols provide reliable, end-to-end communication between a source and a destination in a network. The Transmission Control Protocol (TCP) uses backward error correction, where the destination explicitly returns feedback to the source. Forward error correction (FEC) can also be used for transport; here the source includes enough redundancy in the encoding symbols to allow the destination to decode the message. In this paper, we compare the performance of two transport schemes, TCP and LT, a scheme based on rateless FEC codes, in a wireless ad hoc network when topology-transparent scheduling is used for channel access. These schedules are derived from cover-free families, a type of combinatorial design. They provide a mechanism to guarantee collision-free communication between any two nodes provided that each of the N nodes of the network has at most a specified number D of active (transmitting) neighbours. We find that LT outperforms TCP in more strenuous network conditions. To Frank Hwang on the occasion of his sixty-fifth birthday.     

Equal Processing Time Bicriteria Scheduling on Parallel Machines

We consider the problem of scheduling jobs on parallel, identical machines so as to minimize a primary and a secondary criteria. All the jobs are assumed to have identical processing times. Polynomial time algorithms, that generate optimal solutions, are presented for various combinations of primary and secondary criteria.     

3-Partitioning Problems for Maximizing the Minimum Load

The optimization versions of the 3-Partitioning and the Kernel 3-Partitioning problems are considered in this paper. For the objective to maximize the minimum load of the m subsets, it is shown that the MODIFIED LPT algorithm has performance ratios (3m – 1)/(4m – 2) and (2m – 1)/(3m – 2), respectively, in the worst case.     

大规模定制模式下供应链计划调度优化分析

大规模定制模式下供应链生产计划调度问题是一个典型的随机需求与随机资源约束的 多目标动态优化问题. 在对该问题特征翔实描述,分析所总结的理论研究成果基础上,提出了 完整的随机多目标动态优化数学模型. 通过实例简要分析了优化目标的成熟性及模型的可行 性. 最后,指出了较为重要的动态优化调度过程的实现,并进行了实践应用过程的验证与说明     

Minimization of maximum lateness under linear deterioration

This paper considers a single-machine scheduling problem to minimize the maximum lateness. The processing time of each job is a linear function of the time when the job starts processing. This problem is known to be -hard in the literature. In this paper, we design a branch-and-bound algorithm for deriving exact solutions by incorporating several properties concerning dominance relations and lower bounds. These properties produce synergic effects in accelerating the solution finding process such that the algorithm can solve problems of 100 jobs within 1 min on average. To compose approximate solutions, we revise a heuristic algorithm available in the literature and propose several hybrid variants. Numerical results evince that the proposed approaches are very effective in successfully reporting optimal solutions for most of the test cases.     

Practical Implications of Preference‐Based Conference Scheduling

Conference scheduling involves organizing presentations into sessions which are assigned to time periods and rooms. This includes assuring a feasible utilization of time periods and rooms, and avoiding individual schedule conflicts. The problem increases in complexity by considering the preferences of presenters: for time periods, for rooms, etc. A greater level of complexity comes from considering the preferences of conference attendees, which we define as preference‐based conference scheduling (PBCS). This article provides a structure on which PBCS problems are founded, including empirical demonstration of solution techniques. In addition, real‐world strategic planning issues of flexibility and preference detail are explored.     

考虑旅客跨区间流转的机票多预定区间折扣优化模型研究

多预定区间差异化折扣逐渐成为机票收益管理的重要分支。本文提出了一种新的收益管理模型：基于顾客跨区间流转的收益管理模型,并给出了二分法迭代求解方法。假设各个预订时间区间的潜在需求可以通过大数据手段进行预测,首先结合旅客的价格敏感和潜在需求跨时间段流转的特性分析了各区间的需求函数,然后结合需求函数构建了多预定区间折扣优化模型。由于该模型属于动态的收益管理模型,因此构建了一种动态求解方法——二分迭代法。最后,依据航空公司的实际情况设计了两个仿真实验。实验计算结果不仅验证了新模型和算法的有效性,而且得出一些比较有用的结论：（1）票价与提前购票时间不存在单调的线性关系;（2）预订区间远离离港日折扣逐渐变大,靠近离港日的折扣会逐渐减少,但是包含离港日的预订区间的折扣又会变大;（3）流转率越高则折扣越少;（4）价格敏感系数越高折扣越高;（5）流转率通过改变价格敏感系数而影响折扣的大小。本文给出的折扣优化决策模型符合旅游产品多预定区间折扣决策的实践,可以为机票、酒店、景区等多种旅游产品的票价决策提供有益参考。     

资源受限下平行工序顺序对优化的0-1规划模型

资源受限是工程项目时刻都可能面对的挑战。由于资源限制,需要将原项目计划中相互之间无优先关系的平行工序调整为顺序工序。平行工序顺序化可导致项目工期延迟,因此需考虑如何使项目工期延迟最小。该平行工序顺序优化问题是项目调度问题,也是排列组合问题,通常难度很大,包括一些NP-hard问题。本文主要研究该问题的一类典型子问题——平行工序顺序对优化,即如何将项目中某2n个平行工序调整为n个顺序工序对,并且对项目工期的影响最小。该问题的总方案数可达到（2n）!/n!。本文借助工序网络（如CPM网络）,运用简单的时间参数量化了平行工序顺序化对项目工期的影响,进而降低问题的求解难度,建立了纯0-1规划模型。实验验证了该模型的求解效率,求解100个平行工序规模的问题平均耗时0.2605秒,而求解500个平行工序规模的问题平均耗时10.66秒。     

Scheduling challenges among workers in low-wage hourly jobs: similarities and differences among workers in standard- and nonstandard-hour jobs

Work schedules are a central theme in the work–family challenges of low-wage hourly workers. Yet, research on scheduling patterns among this worker population has primarily focused on nonstandard schedules. We know very little about the scheduling patterns of workers in hourly jobs with standard fixed schedules. Knowledge about the key scheduling challenges by schedule type is necessary to develop targeted workplace solutions, such as flexible work arrangements, to enhance work–life fit among workers in low-wage hourly jobs. Using the 2008 National Study of the Changing Workforce, bivariate and multivariate analyses were employed to determine (1) the prevalence of rigid, unpredictable and unstable work schedules among low-wage hourly workers employed in jobs with standard and nonstandard schedules and whether there is variation in these scheduling practices among full- and part-time workers; and (2) the individual or job characteristics that influence the odds of experiencing rigid, unpredictable or unstable work schedules. Results indicate that rigid and unpredictable schedule practices are most prevalent among low-wage hourly workers in full-time standard-hour jobs and part-time nonstandard-hour jobs, while unstable scheduling practices are most prevalent among hourly workers in full- and part-time nonstandard-hour jobs. Implications and limitations of the research are discussed.     

Information quality deficiencies in delivery schedules and their impact on production scheduling

The purpose of this paper is to explore how different delivery schedule characteristics affect the quality of shared delivery schedule information and, in turn, how deficiencies in quality affect a supplier’s production scheduling process. It describes a case study conducted in the Swedish automotive industry involving a supplier that operates as the first-, second- and third-tier supplier to an original equipment manufacturer. The study reveals how four delivery schedule characteristics – namely, receiving frequency, planning period, frozen period and demand variation – create information quality (IQ) deficiencies in five dimensions of IQ: completeness, conciseness, reliability, timeliness and credibility. At the same time, it demonstrates how such deficiencies affect the supplier’s production scheduling process by requiring additional rescheduling, reworking and follow-up activities as well as additional capacity problems, safety time, safety stock and backlogs. In effect, the paper extends previous IQ-related research by considering IQ in delivery schedules.