Constructing robust crew schedules with bicriteria optimization

Optimization‐based computer systems are used by many airlines to solve crew planning problems by constructing minimal cost tours of duty. However, today airlines do not only require cost effective solutions, but are also very interested in robust solutions. A more robust solution is understood to be one where disruptions in the schedule (due to delays) are less likely to be propagated into the future, causing delays of subsequent flights. Current scheduling systems based solely on cost do not automatically provide robust solutions. These considerations lead to a multiobjective framework, as the maximization of robustness will be in conflict with the minimization of cost. For example crew changing aircraft within a duty period is discouraged if inadequate ground time is provided. We develop a bicriteria optimization framework to generate Pareto optimal schedules for the domestic airline. A Pareto optimal schedule is one which does not allow an improvement in cost and robustness at the same time. We developed a method to solve the bicriteria problem, implemented it and tested it with actual airline data. Our results show that considerable gain in robustness can be achieved with a small increase in cost. The additional cost is mainly due to an increase in overnights, which allows for a reduction of the number of aircraft changes. Copyright © 2003 John Wiley & Sons, Ltd.     

Effects of Performance-Based Pay Systems on Quantity and Quality in Computer Programming

This experiment was conducted to investigate the effects of quality-contingent pay systems on quantity and quality. Three computer science students were paid to create simple computer programs across 25 sessions. A multiple-baseline across subjects design was used to compare the effects of three kinds of pay systems; pay-for-hour, pay-for-quantity, and pay-for-quality systems. The quantity was higher when pay was based on the quantity of the programs produced, and the quality was highest when pay was based on the quality of the programs. The production cost including quality inspection costs was highest when pay was based on the time worked.     

题库智能化组卷的心理计量理论与方法

现代教育成就测验的广泛应用,促使题库技术迅速发展。现代教育测量理论与计算机技术的结合,更使智能化组卷成为可能。本文报告了以项目反应理论为指导,并改进一般线性规划法为分步离差加权模型法,编制程序在高等教育自学考试“逻辑学”题库上,成功实现智能化组卷的研究成果,从而为计算机技术在题库建设中的应用作了新的探讨。     

Answer Sets and Qualitative Optimization

One of the major reasons for the success of answer set programmingin recent years was the shift from a theorem proving to a constraintprogramming view: problems are represented such that stablemodels, respectively answer sets, rather than theorems correspondto solutions. This shift in perspective proved extremely fruitfulin many areas. We believe that going one step further from a"hard" to a "soft" constraint programming paradigm, or, in otherwords, to a paradigm of qualitative optimization, will proveequally fruitful. In this paper we try to support this claimby showing that several generic problems in logic based problemsolving can be understood as qualitative optimization problems,and that these problems have simple and elegant formulationsgiven adequate optimization constructs in the knowledge representationlanguage.     

Optimal Least-Squares Unidimensional Scaling: Improved Branch-and-Bound Procedures and Comparison to Dynamic Programming

There are two well-known methods for obtaining a guaranteed globally optimal solution to the problem of least-squares unidimensional scaling of a symmetric dissimilarity matrix: (a) dynamic programming, and (b) branch-and-bound. Dynamic programming is generally more efficient than branch-and-bound, but the former is limited to matrices with approximately 26 or fewer objects because of computer memory limitations. We present some new branch-and-bound procedures that improve computational efficiency, and enable guaranteed globally optimal solutions to be obtained for matrices with up to 35 objects. Experimental tests were conducted to compare the relative performances of the new procedures, a previously published branch-and-bound algorithm, and a dynamic programming solution strategy. These experiments, which included both synthetic and empirical dissimilarity matrices, yielded the following findings: (a) the new branch-and-bound procedures were often drastically more efficient than the previously published branch-and-bound algorithm, (b) when computationally feasible, the dynamic programming approach was more efficient than each of the branch-and-bound procedures, and (c) the new branch-and-bound procedures require minimal computer memory and can provide optimal solutions for matrices that are too large for dynamic programming implementation.The authors gratefully acknowledge the helpful comments of three anonymous reviewers and the Editor. We especially thank Larry Hubert and one of the reviewers for providing us with the MATLAB files for optimal and heuristic least-squares unidimensional scaling methods.This revised article was published online in June 2005 with all corrections incorporated.     

交互自然性的心理结构及其影响

本文通过3个研究探究了交互自然性的心理结构及其影响。研究1通过开展字典检索, 文献回顾和专家访谈, 得到了包含有9个条目的初始量表。研究2问卷调查了353名智能网联汽车用户, 探索性因素分析发现了两因素结构 (“通达舒畅”和“随景应人”)。后续分析表明这两个因素对满意度等关键效标有显著独特的预测作用。研究3使用新样本(n = 349) 验证了双因素模型的稳定性, 还发现这两个交互自然性体验维度对推荐意愿、忠诚感等重要变量也有显著预测作用, 此外还发现, 通达舒畅更多受到基本驾驶辅助系统等功能的影响, 而随景应人更多受到交互和智能相关功能的影响。本文进一步讨论了该量表如何用于未来的人机交互研究。     

工作记忆广度与汉语句子语境效应的关系

采用计算机快速系列视觉呈现技术,以反应时为指标,利用命名法,从工作记忆容量个体差异的角度,探讨汉语句子阅读中的语境效应。本研究将句子的语境效应分为两个来源：一个是自动激活扩散的词汇之间的语义启动,另一个是相互作用的句子水平的主题启动。结果表明：词汇间的语义启动不受工作记忆容量的影响,并且不易受到无关记忆任务的干扰。句子水平的主题启动会受到工作记忆容量的影响：工作记忆广度较高的读者能出现主题水平的语境效应,但是在无关记忆任务的干扰下,句子主题水平的语境效应消失;低广度的读者在无外部记忆负荷和有外部记忆负荷两种条件下都没有出现主题水平的语境效应。工作记忆容量对那些需要较多认知资源的加工过程产生显著的影响,实验结果符合工作记忆容量限制理论     

The effects of exergaming on physical activity in a third-grade physical education class

We compared the effects of exergaming and traditional physical education on physical activity among 4 active children who were not overweight and who had experience with the exergaming activities prior to the study. Results showed that exergaming produced substantially higher percentages of physical activity and opportunity to engage in physical activity. In addition, an evaluation of the exergaming equipment showed that exergaming stations were associated with differential levels of physical activity across participants.     

潜变量交互效应模型标准化估计中的检验问题

讨论了潜变量交互效应模型是否能直接用统计软件输出的原始估计的t值对模型的标准化估计进行检验的问题,详细介绍了标准化估计的t值计算及其难点,用Bootstrap方法算出标准化估计的标准误和相应的t值（记为t_bs）,并将其与原始估计的t值比较.结果发现,当原始估计t值超过3时,无论用t值还是用t_ bs检验,结果都是显著,即可以使用t值进行检验.而当t值不超过3时,与t_bs很接近,也可以用t值检验,但t值在临界值附近（例如1.5 ～2.5）时,最好还是使用Bootstrap法计算t_bs进行检验.