Evaluating a range of learning schedules: hybrid training schedules may be as good as or better than distributed practice for some tasks

We investigated theoretically and empirically a range of training schedules on tasks with three knowledge types: declarative, procedural, and perceptual-motor. We predicted performance for 6435 potential eight-block training schedules with ACT-R's declarative memory equations. Hybrid training schedules (schedules consisting of distributed and massed practice) were predicted to produce better performance than purely distributed or massed training schedules. The results of an empirical study (N = 40) testing four exemplar schedules indicated a more complex picture. There were no statistical differences among the groups in the declarative and procedural tasks. We also found that participants in the hybrid practice groups produced reliably better performance than ones in the distributed practice group for the perceptual-motor task – the results indicate training schedules with some spacing and some intensiveness may lead to better performance, particularly for perceptual-motor tasks, and that tasks with mixed types of knowledge might be better taught with a hybrid schedule.     

非确定处理调度图的启发式数据分配方法

本文通过减少确定处理调度图（ＰＳＧ）的限制条件,增加某些不确定量,引入了非确定处理调度图,并提出了非确定处理调度图的启发式数据分配算法。     

基于改进权重自适应GA的冷连轧轧制规程多目标优化

针对聚合多目标优化方法的权重难以确定的问题, 提出了一种改进的权重自适应方法, 并以遗传算法为基础对冷连轧轧制规程进行多目标优化. 首先, 结合某冷轧厂实际的轧制规程优化过程, 选取等功率裕量、轧制能耗及带钢打滑概率作为优化目标, 建立了冷连轧轧制规程的多目标优化模型. 然后将改进的权重自适应遗传算法(GA)应用于不同规格的带钢轧制规程多目标优化中, 结果表明, 与实际应用的轧制规程相比, 该方法有效的降低了3个目标函数的值; 与权重自适应GA相比, 改进的权重自适应GA的针对性更强, 同时重要性高的目标收敛速度更快.     

The Problem of Schedule Construction in the Joint Design of Hardware and Software

Data structures for direct and parametric representation of schedules are considered and corresponding systems of operations for correcting schedules are introduced. Those operations are used for designing iteration algorithms of schedule construction. It is proved that the direct and parametric representation of schedules and the corresponding correction operations allow the construction of iteration algorithms that ensure the transformation of an arbitrary schedule into an optimal one in a linear number of iteration steps relative to the number of scheduled tasks. Moreover, those algorithms ensure that schedules obtained at all iteration steps are feasible.     

On the complexity of concurrency control using semantic information

In the presence of semantic information, serializability is too strong a correctness criterion and unnecessarily restricts concurrency. Many researchers have investigated the use of semantic information to allow interleaving among transactions which are non-serializable, but which nonetheless preserves the consistency of the database and is acceptable to the users. In this paper we consider a class of schedules, calledconflict-correct schedules, first proposed by Farrag and Özsu, which enlarges upon the class of serializable schedules by taking semantic information of transactions into account. In this paper we show that the problem of recognizing schedules in this class is NP-complete. Thus it is unlikely that there exists an efficient scheduler which accepts the entire class of conflict-correct schedules.This research was partially supported by MICRO grants with IBM and XEROX Corporations.     

Using a circadian rhythms model to evaluate shift schedules

As long as the need for shiftwork exists, so will the demand for an optimal scheduling strategy that balances the needs of both industry and the shiftworker. One aim is for schedules that require workers to be on duty during the times that they are most naturally alert and awake. Czeisler et al. (1982) developed a set of circadian rhythm based guidelines intended to aid in designing such shiftwork schedules. This paper takes research one step further by testing such empirical criteria in a mathematical setting. The two-oscillator model of free-run human circadian rhythms developed by Kronauer et al. (1982) was modified to represent the circadian rhythms of a shiftworker on a pre-selected shiftwork schedule. Numerical simulations were used to compare the circadian rhythms produced from a variety of shiftwork schedules to the free-run rhythms. Shift schedules that resulted in circadian rhythms closest to the free-run rhythms were identified as preferred schedules. The numerical results supported Czeisler's findings (1982), indicating the best shift schedules adopt a slow, forward-shifting rotation pattern, rotate shifts after 2-week periods and allow an average of 2 days off per week.     

Analysis of finite length annealing schedules

By constructing a master equation for the distribution of outcomes from simulated annealing, we are able to characterize this process exactly for arbitrary annealing schedules on extremely small problems. Two sorts of numerical experiments are reported, using this formalism. First, annealing schedules are found which minimize the cut cost of partitioning a highly symmetric weighted graph, using a fixed number of Monte Carlo search steps. The experiments yield some surprising results, which sharpen our understanding of the problems inherent in trying to optimize a stochastic search. For example, optimal annealing schedules are not monotone decreasing in temperature. Second, we construct configuration spaces of random energies and varying connectivity. These are used to compare different annealing schedules which are common in the literature. The experiments also provide an occasion to contrast annealing schedules derived from asymptotic, worst-case bounds on convergence to the global optimum with adaptive schedules which attempt to maintain the system close to equilibrium throughout the annealing process.     

Analysis of finite length annealing schedules

By constructing a master equation for the distribution of outcomes from simulated annealing, we are able to characterize this process exactly for arbitrary annealing schedules on extremely small problems. Two sorts of numerical experiments are reported, using this formalism. First, annealing schedules are found which minimize the cut cost of partitioning a highly symmetric weighted graph, using a fixed number of Monte Carlo search steps. The experiments yield some surprising results, which sharpen our understanding of the problems inherent in trying to optimize a stochastic search. For example, optimal annealing schedules are not monotone decreasing in temperature. Second, we construct configuration spaces of random energies and varying connectivity. These are used to compare different annealing schedules which are common in the literature. The experiments also provide an occasion to contrast annealing schedules derived from asymptotic, worst-case bounds on convergence to the global optimum with adaptive schedules which attempt to maintain the system close to equilibrium throughout the annealing process.     

某些调度问题区间摄动鲁棒性的研究

由于生产环境中常常存在着各种不确定因素,生产调度方案的鲁棒性是生产实际中 的一个重要问题.文中对一些调度问题中最优调度关于加工时间及交付期在某一闭区间上任 意变化时的不变性进行了研究,得到了问题 最优调度不变的充要条件,问题 最优调度不变的充分条件.     

Using a circadian rhythms model to evaluate shift schedules

As long as the need for shiftwork exists, so will the demand for an optimal scheduling strategy that balances the needs of both industry and the shiftworker. One aim is for schedules that require workers to be on duty during the times that they are most naturally alert and awake. Czeisler et al. (1982) developed a set of circadian rhythm based guidelines intended to aid in designing such shiftwork schedules. This paper takes research one step further by testing such empirical criteria in a mathematical setting. The two-oscillator model of free-run human circadian rhythms developed by Kronauer et al. (1982) was modified to represent the circadian rhythms of a shiftworker on a pre-selected shiftwork schedule. Numerical simulations were used to compare the circadian rhythms produced from a variety of shiftwork schedules to the free-run rhythms. Shift schedules that resulted in circadian rhythms closest to the free-run rhythms were identified as preferred schedules. The numerical results supported Czeisler's findings (1982), indicating the best shift schedules adopt a slow, forward-shifting rotation pattern, rotate shifts after 2-week periods and allow an average of 2 days o^ff per week.     

车间调度DSS设计的优化方法

一个复杂的制造系统不仅可能涉及到成千上万道车间调度工序,而且工序的变更又可能导致相当大的调度规模,因此车间调度是一种决策模型,应用该模型设计的车间调度决策支持系统可以在短时间内有效地提供一种优化决策。遗传算法是一种高效并行的全局搜索方法,文章通过对遗传算法关键因素的讨论,研究了SFSDSS设计的优化方法。     

Two simple and effective heuristics for minimizing the makespan in non-permutation flow shops

We propose a constructive and an iterated local search heuristic for minimizing the makespan in the non-permutation flow shop scheduling problem. Both heuristics are based on the observation that optimal non-permutation schedules often exhibit a permutation structure with a few local job inversions. In computational experiments we compare our heuristics to the best heuristics for finding non-permutation and permutation flow shop schedules, and evaluate the reduction in makespan and buffer size that can be achieved by non-permutation schedules.     

Metaheuristics for scheduling a non-permutation flowline manufacturing cell with sequence dependent family setup times

The broad applications of cellular manufacturing make flowline manufacturing cell scheduling problems with sequence dependent family setup times a core topic in the field of scheduling. Due to computational complexity, almost all published studies focus on using permutation schedules to deal with this problem. To explore the potential effectiveness of treating this argument using non-permutation schedules, three prominent types of metaheuristics—a simulated annealing, a genetic algorithm and a tabu search—are proposed and empirically evaluated. The experimental results demonstrate that in general, the improvement made by non-permutation schedules over permutation schedules for the due-date-based performance criteria were significantly better than that for the completion-time-based criteria. The results of this study will provide practitioners a guideline as to when to adopt a non-permutation schedule, which may exhibit better performance with additional computational efforts.     

A formal mapping-based approach for distributed schedule coordination on projects

Construction projects involve a large number of participants with overlapping scope of work. Coordination of their activities is usually an iterative manual task undertaken by a general contractor that is often unaware of the detailed constraints of other participants. Project schedules play a key role in this coordination and form the backbone of almost all current approaches to process coordination. However, no single schedule represents the perspective of all participants involved in a project. Rather, each participant keeps in some manner a schedule for its own activities, resulting in multiple schedules that need to be coordinated. The current literature does not support simultaneous reasoning across multiple distributed, overlapping schedules. This paper introduces constructs to formalize the integration of participants’ overlapping schedules that represent the same project tasks, but use a different set breakdown structures and level of detail. Implementation of these constructs allows linking of the master schedule to the other participants’ schedules thereby representing the perspectives of all project participants. This integrated perspective facilitates initial schedule coordination and allows rapid identification of schedule conflicts in response to any schedule changes.     

Recognition of process patterns for BIM-based construction schedules

Construction scheduling is a very demanding and time intensive process. Building information modeling (BIM) is becoming increasingly important for planning and scheduling, as it provides significant support for this difficult assignment. Further improvements can be achieved by applying predefined process templates for BIM-based schedules. It can reduce the planning time and thus increase the productivity. However, a manual definition of proper and application-specific process templates is very challenging. The automatic detection of recurring similar configurations of construction processes, called process patterns, would greatly support this complex task. Identified process patterns can be subsequently generalized, supporting the design of process templates. This contribution presents an overall concept for process pattern recognition in BIM-based construction schedules by applying graph-based methods. Due to the fact that graph matching algorithms are in general very time- and resource-consuming, an indexing technique based on features is used to solve this problem more efficiently. The paper focuses on the estimation of similarity in construction schedules, describing feature-based methods and similarity measure definitions in detail. Another emphasis is the preparation of schedules for the recognition of process patterns, including decomposition of schedules into smaller parts, referred to as subschedules, and normalization of features. The potential of this concept is demonstrated by two different case studies. The proper results of the evaluation show that the proposed method and similarity metrics are sufficient for the recognition of process patterns in construction schedules.     

The problem of assigning students to course sections in a large engineering school

In some universities, complete course schedules are made available to students at the time of registration. Typically these schedules give the room number, instructor and time for each session. Students use this information to select their courses. A computer program then allocates students to course sections so as to provide students with satisfactory schedules, to equalize roughly the number of students in all sections of the same course and to respect room capacities. The authors designed and implemented such a program at the Ecole Polytechnique de Montreal, one of Canada's leading Engineering Schools.     

Unifying concurrency control and recovery of transactions with semantically rich operations

The classical theory of transaction management contains two different aspects, namely concurrency control and recovery, which ensure serializability and atomicity of transaction executions, respectively. Although concurrency control and recovery are not independent of each other, the criteria for these two aspects were developed orthogonally and as a result, in most cases these criteria are incompatible with each other.

Recently a unified theory of concurrency control and recovery for databases with read and write operations has been introduced in [19, 1] that allows reasoning about serializability and atomicity within the same framework. In [19, 1] a class of schedules (called prefix reducible), which guarantees both serializability and atomicity in a failure prone environment with read/write operations was introduced. Several protocols were developed to generate such schedules by a database concurrency control mechanism.

We present here a unified transaction model for databases with an arbitrary set of semantically rich operations. We investigate constructive characterization of the class of prefix reducible schedules with semantically rich operations. It turns out that unlike databases with only read/write operations, the exact characterization of prefix reducible schedules in databases with arbitrary operations is rather infeasible. Thus, we propose here several sufficiently rich subclasses of prefix reducible schedules, and design concurrency control protocols that guarantee both serializability and atomicity for schedules from these classes.     

基于统计学的软件系统预恢复时间阈值计算策略

软件系统的预恢复是一种预防和主动的容错技术。本文提出了一种基于统计学的软件系统自恢复时间阈值计算算法。该算法基于满足软件系统可用性概率最大化的思想，在系统性能衰退时间分布未知的情况下，根据一定量的性能衰退的检测数据，计算出优化的软件系统自恢复时间闽值。仿真实验结果表明计算结果合理、稳定性好，能有效地应用于实际系统中。     

Makespan distribution of permutation flowshop schedules

The makespan distribution of permutation flowshop schedules has been a topic of debate for almost fifty years. Many researchers have confirmed or doubted the famous claim that the makespan distribution of permutation flowshop schedules is asymptotically normal if the number of jobs is sufficiently large. This paper theoretically and empirically investigates the makespan distribution of permutation flowshop schedules and shows that the normality claim is not valid for the job-dominated and machine-dominated flowshops. Errors in the proof of normality of the makespan distribution of permutation flowshop schedules are pointed out. It is shown that the makespan distribution of a permutation flowshop scheduling problem depends on the number of jobs as well as the number of machines.     

Random and Periodic Sleep Schedules for Target Detection in Sensor Networks

We study random and periodic sleep schedules from the point of view of delay in detecting the target.We consider sleep schedules in which a sensor in"inactive"mode wakes up either randomly or periodically to detect presence of the target within its vicinity resulting into two sleep schedules:(a)random wake-up schedule,and(b)periodic wake-up schedule respectively.Specifically,we analyse and obtain for the random wake-up schedule the expected delay in detection, and the delay,such that with probability P,the delay is less than the computed value.For the periodic wake-up schedule we show that there exists an upper bound on the delay.Further we compute the average value of delay.We have shown that the theoretically computed averages and the upper bounds on the delay match with the simulation results for the random wake-up and periodic wake-up schedules.