多次抢占项目调度问题的混合遗传算法

研究多次抢占式资源受限的项目调度问题，假设任意时间点可作为资源抢占节点且抢占次数不受限制，建立满足多次资源抢占的线性整数规划模型并提出改进遗传算法对其进行求解。为克服遗传算法（GA）局部搜索能力缺陷，在算法中引入禁忌搜索（TS）进一步优化子代。针对性地设计了允许多次抢占的基于工作优先级编码策略以及串行调度方案生成机制。通过测试算例集实验调试算法参数，并以标准算例集（Project Scheduling Problem Library，PSPLIB）对算法进行可行性检验。实验结果表明，资源受限项目调度问题中引入多次抢占机制能有效缩减项目工期，设计的算法对问题求解效果良好。     

求解RCPSP问题的带分布估计的差异演化算法

提出一种带分布估计的差异演化算法（DEED）用于求解资源受限项目调度问题（RCPSP）。该算法基于差异演化（DE）算法,利用分布估计算法（EDA）能够获得问题解空间的全局信息以及变量间的相互联系,以指导算法搜索过程,并对最优解的分布进行预测。DEED算法充分利用DE收敛速度快和EDA全局搜索优点。经标准问题库（PSPLIB）的单模式问题集验证,并与当前流行的算法进行比较,表明了DEED算法的有效性。     

随机资源约束项目调度问题基于序的果蝇算法

针对项目活动工期为随机变量的资源约束项目调度问题,提出一种基于序的果蝇算法.为了实现随机环境下解的有效评价,提出一种预选机制,并采用基于序的最优计算量分配技术.为了使果蝇算法能够求解资源约束项目调度问题,采用交换操作执行果蝇算法的嗅觉搜索,并采用保优更新操作执行视觉搜索.为了均衡算法的局部搜索和全局搜索能力,在标准果蝇算法中引入了协作进化环节并采用两点交叉操作加以实现.在不同随机分布的情况下,采用标准测试集进行仿真测试.与现有算法的比较结果验证了所提预选机制和基于序的果蝇算法的有效性.     

考虑柔性资源能力差异的项目调度问题

在资源受限项目调度问题中,将可再生资源进一步拓展为具有能力差异的柔性资源,建立考虑能力差异的柔性资源受限项目调度问题模型,该模型是对传统资源约束项目调度问题（RCPSP）更接近实际的拓展。为了求解该模型,提出一种基于活动序列表示的粒子群算法,在粒子解码过程中运用了基于优先规则的柔性资源-能力分配算法,在此基础上详细介绍了改进的串行调度生成方案与改进的并行调度生成方案、算法框架、选择性粒子更新方法。通过在改造的项目调度测试问题集上进行数值实验,证明了算法的可行性和有效性,其中使用改进串行调度生成方案与最匹配资源优先规则的粒子群算法具有较好的求解性能。     

蜂群算法求解资源受限项目调度问题及仿真

蜂群算法作为一种较为新颖的启发式算法已经在多种类型的优化问题求解过程中表现了优秀的性能.针对蜂群算法在项目调度问题中的模型求解资源受限的问题,提出对求解方法进行改进,采用人工蜂群算法和蜂群优化算法两类典型的蜂群算法,对资源受限项目调度问题进行优化设计,并在benchmark上进行仿真并与传统的调度优化算法进行比较.实验结果表明,新设计的两类蜂群算法在调度成功率和收敛速度方面均有更好表现,人工蜂群算法求解的质量方面更优,蜂群算法在收敛速度上更具有优势.     

蚁群算法在资源受限项目调度问题中的应用

资源受限的项目调度问题(RCPSP,Resource-ConstrainedProjectSchedulingProblems)已经被证明是一种NP-hard的组合优化问题,随着问题规模的增大,使用经典的数学方法如数学规划等方法,已经很难解决问题。论文提出了一种用于求解资源受限的项目调度问题的蚁群算法。针对资源受限的项目调度问题的具体特点,提出了蚂蚁巡游网络图的动态生成方式,信息素的表示及更新方式,以及启发信息的计算方法。针对PSPLIB中的测试集对算法中的主要参数进行了优化,最后,使用PSPLIB中的四种测试集对算法进行了测试,计算结果表明了算法的有效性。     

求解置换流水车间调度问题的混合鸟群算法

针对置换流水车间调度问题（PFSP）,提出了一种混合鸟群算法（HBSA）以更加有效地最小化最大完工时间。首先,为了改善初始种群的质量和多样性,结合一种基于NEH（Nawaz-Enscore-Ham）的启发式算法和混沌映射提出了一种新的种群初始化方法;其次,为了使算法能够处理离散的调度问题,采用最大排序值（LRV）规则将连续的位置值转换为离散的工件排序;最后,为了强化算法对解空间的探索能力,借鉴变邻域搜索（VNS）和迭代贪婪（IG）算法的思想针对个体最佳工件排序和种群最佳工件排序分别提出了局部搜索方法。针对广泛使用的Rec标准测试集进行了仿真测试,并与目前有效的元启发式算法——刘等提出的混合差分进化算法（L-HDE）、混合共生生物搜索算法（HSOS）、离散狼群算法（DWPA）、多班级教学优化算法（MCTLBO）相比较,结果表明,HBSA取得的最佳相对误差（BRE）、平均相对误差（ARE）的平均值比上述四种算法至少下降了73.3%、76.8%,从而证明HBSA具有更强的寻优能力和更好的稳定性。尤其是针对测试算例Rec25和Rec27,仅HBSA的求解结果达到了目前已知最优解,进一步证明了其优越性。     

求解广义优先关系下多技能人员项目调度问题的改进布谷鸟搜索算法

为解决传统的完成-开始时序不能满足描述真实项目调度顺序要求的问题,引入广义优先关系(GPRs)及改进的AON描述任务的时序约束。提出将布谷鸟搜索算法应用于求解广义优先关系下的多技能人力资源项目调度问题(MS-RCPSP/GPRs)中的构想,建立了基于改进布谷鸟搜索算法(ICS)的求解方法,采用Powell局部改进技术和精英保留策略,并给出了算法流程。基于相关案例生成器生成该问题的数据集,实验结果表明ICS是一种求解MS-RCPSP/GPRs的有效方法,对解决实际问题具有重要意义。     

目标边界点集的层次化描述及其形状检索应用

提出用于轮廓线形状和区域形状图像检索的形状描述方法,该方法将目标形状的边界（包括内边界）表示为一个无序的点集,沿各方向对点集的迭代分割,建立层次化的边界点集描述模型.通过对各层形状边界的分割比和分散度的几何特征度量,产生各层的形状特征描述,对它们进行组合,建立对目标形状的层次化描述.两个目标形状的差异性度量定义为它们的层次化描述子的L-1距离.该方法具有：（1）通用性.能够描述轮廓线形状和区域形状这两种不同类型的形状;（2）可扩展性.基于所提出的分层描述框架,可以将分割比和分散度这两种几何度量进行扩展,纳入更多其他几何特征度量,以进一步提高形状描述的精度;（3）多尺度描述特性.提出的分层的描述机制,使得描述子具有内在的由粗到细的形状表征能力;（4）较低的计算复杂性.由于仅仅计算目标图像的边界像素点,使得算法具有较高的计算效率.用MPEG-7 CE-2区域形状图像库和MPEG-7 CE-1轮廓线形状图像库这两个标准测试集对该方法进行评估,并与同类的其他形状描述方法进行比较,实验结果表明：提出的方法在综合考虑检索精确率、检索效率和一般应用能力等指标的情况下,其性能上要优于各种参与比较的方法.     

动态选择与替换策略的多目标约束优化进化算法

提出一种基于动态选择与替换策略的多目标优化进化算法用于求解约束优化问题.新算法首先将约束优化问题转化为两个目标的多目标优化问题,基于Parto支配关系,把初始种群分为Pareto子集和Non-Pareto子集,引入一种非劣个体保护偏好策略,动态选取一定比例的最优非劣个体直接进入下一代群体,剩下的非劣个体随机替代Pareto子集中的个体.Pareto子集和Non-Pareto子集分别进行单形交叉和多样性变异操作产生新的子种群.对13个标准测试问题的数值实验结果表明新算法的有效性.     

Benchmark-problem instances for static scheduling of task graphs with communication delays on homogeneous multiprocessor systems

Scheduling program tasks on processors is at the core of the efficient use of multiprocessor systems. Most task-scheduling problems are known to be NP-Hard and, thus, heuristics are the method of choice in all but the simplest cases. The utilization of acknowledged sets of benchmark-problem instances is essential for the correct comparison and analysis of heuristics. Yet, such sets are not available for several important classes of scheduling problems, including multiprocessor scheduling problem with communication delays (MSPCD) where one is interested in scheduling dependent tasks onto homogeneous multiprocessor systems, with processors connected in an arbitrary way, while explicitly accounting for the time required to transfer data between tasks allocated to different processors. We propose test-problem instances for the MSPCD that are representative in terms of number of processors, type of multiprocessor architecture, number of tasks to be scheduled, and task graph characteristics (task execution times, communication costs, and density of dependencies between tasks). Moreover, we define our task-graph generators in a way appropriate to ensure that the corresponding problem instances obey the theoretical principles recently proposed in the literature.     

直觉模糊集相似度遗传算法求解多目标车间调度问题

为了提高高维多目标置换流水车间调度问题的求解质量,提出基于直觉模糊集相似度的遗传算法(similarity of intuitionistic fuzzy sets GA,SIFS_GA).算法中分别将参考解和Pareto解映射为参考解直觉模糊集和Pareto解直觉模糊集.计算两个集合之间的直觉模糊相似度,用以判断Pareto解的优劣.以直觉模糊集相似度值引导多目标遗传算法进化.对6个CEC标准测试集与10个流水车间调度测试实例进行仿真实验,结果表明SIFS_GA算法性能优于常用的多目标优化算法,且可以有效解决多目标置换流水车间调度问题,尤其在解决规模较大的问题上是一种有效方法.     

A random generator of resource-constrained multi-project network problems

Many scheduling problems in project management, manufacturing, and elsewhere require the generation of activity networks to test proposed solution methods. Single-network generators have been used for the resource-constrained project scheduling problem (RCPSP). Since the first single-network generator was proposed in 1993, several advances have been reported in the literature. However, these generators create only one network or project at a time; they cannot generate multi-project problems to desired specifications. This paper presents the first multi-network problem generator. It is especially useful for investigating the resource-constrained multi-project scheduling problem (RCMPSP), where a controlled set of multi-project test problems is crucial for analyzing the performance of solution methods. In addition to the single-project characteristics handled by existing network generators—such as activity duration, resource types and usage, and network size, shape, and complexity—the proposed generator produces multi-project portfolios with controlled resource distributions and amounts of resource contention. To enable the generation of projects with desired levels of network complexity, we also develop several theoretical insights on the effects of network topology on the probability of successful network generation. Finally, we generate 12,320 test problems for a full-factorial experiment and use analysis of means to conclude that the generator produces “near-strongly random” problems. Fully “strongly random” problems require much greater computational expense.     

Generating new test instances by evolving in instance space

Our confidence in the future performance of any algorithm, including optimization algorithms, depends on how carefully we select test instances so that the generalization of algorithm performance on future instances can be inferred. In recent work, we have established a methodology to generate a 2-d representation of the instance space, comprising a set of known test instances. This instance space shows the similarities and differences between the instances using measurable features or properties, and enables the performance of algorithms to be viewed across the instance space, where generalizations can be inferred. The power of this methodology is the insights that can be generated into algorithm strengths and weaknesses by examining the regions in instance space where strong performance can be expected. The representation of the instance space is dependent on the choice of test instances however. In this paper we present a methodology for generating new test instances with controllable properties, by filling observed gaps in the instance space. This enables the generation of rich new sets of test instances to support better the understanding of algorithm strengths and weaknesses. The methodology is demonstrated on graph colouring as a case study.     

A genetic algorithm approach to the multiple machine tool selection problem

A number of earlier researches have emphasized the on-the-job scheduling problems that occur with a single flexible machine. Two solutions to the problem have generally been considered; namely minimization of tool switches and minimization of tool switching instances. Methods used to solve the problems have included KTNS heuristic, dual-based relaxation heuristic, and non-LP-based branch-and-bound methods. However, scant literature has considered the case of job scheduling on multiple parallel machines which invokes another problem involving machine assignment. This paper addresses the problem of job scheduling and machine assignment on a flexible machining workstation (FMW) equipped with multiple parallel machines in a tool-sharing environment. Under these circumstances, the authors have attempted to model the problem with the objective of simultaneously minimizing both the number of tool switches and the number of tool switching instances. Furthermore, a set of realistic constraints has been included in the investigation. A novel genetic algorithm (GA) heuristic has been developed to solve the problem, and performance results show that GA is an appropriate solution.     

Benchmarks for scheduling on a single machine against restrictive and unrestrictive common due dates

We consider the NP-hard problem of scheduling jobs on a single machine against common due dates with respect to earliness and tardiness penalties. The paper covers two aspects: Firstly, we develop a problem generator and solve 280 instances with two new heuristics to obtain upper bounds on the optimal objective function value. Secondly, we demonstrate computationally that our heuristics are efficient in obtaining near-optimal solutions for small problem instances. The generated problem instances in combination with the upper bounds can be used as benchmarks for future approaches in the field of common due-date scheduling.Scope and purposeIn connection with just-in-time production and delivery, earliness as well as tardiness penalties are of interest. Thus scheduling against common due dates has received growing attention during the last decade. Many algorithms have been developed to solve the different variants of this problem. But whenever a new algorithm for scheduling against common due dates is proposed, its quality is assessed only on a few self-generated examples. Hence it is difficult to evaluate the various approaches, particularly in comparison with each other. Therefore the goal of this paper is to present numerous benchmark problems together with some upper bounds on the optimal objective function value.     

RanGen: A Random Network Generator for Activity-on-the-Node Networks

In this paper, we describe RanGen, a random network generator for generating activity-on-the-node networks and accompanying data for different classes of project scheduling problems. The objective is to construct random networks which satisfy preset values of the parameters used to control the hardness of a problem instance. Both parameters which are related to the network topology and resource-related parameters are implemented. The network generator meets the shortcomings of former network generators since it employs a wide range of different parameters which have been shown to serve as possible predictors of the hardness of different project scheduling problems. Some of them have been implemented in former network generators while others have not.     

A multi-agent system for the decentralized resource-constrained multi-project scheduling problem

A restart evolution strategy (RES) for the resource‐constrained project scheduling problem (RCPSP), as well as its integration in a multi‐agent system (MAS) for solving the decentralized resource‐constrained multi‐project scheduling problem (DRCMPSP) will be presented. To evaluate the developed approach, problem instances of the RCPSP taken from the literature with up to 300 activities are used, as well as 80 generated instances of the DRCMPSP, with up to 20 projects and with up to 120 activities each. For 73 instances of the RCPSP, the RES found better solutions than the best ones found so far. In addition, the MAS is suitable for solving large multi‐project instances decentrally. The results for the DRCMPSP instances show that the presented decentralized MAS is competitive with a central solution approach.     

Chaos-based improved immune algorithm (CBIIA) for resource-constrained project scheduling problems

This paper introduces a novel meta-heuristic, the chaos-based improved immune algorithm (CBIIA), for solving resource-constrained project scheduling problems (RCPSP). In RCPSP the activities of a project have to be scheduled with the objective of minimizing total makespan subject to both temporal and resource constraints. The proposed CBIIA is based on the traits of an artificial immune system, chaotic generator and parallel mutation. CBIIA is different from the traditional immune algorithm in its initialization and hypermutation mechanism. Initialization in CBIIA is done by using chaotic generator (Logistic, Tent, and Sinusoidal) instead of conventional random number generator (RNG). The hypermutation is performed by parallel mutation (PM) operator rather than point mutation. Parallel mutation comprises two mutation strategies viz. Gaussian and Cauchy. Gaussian strategy is utilized for small step mutation and Cauchy strategy is for large step mutation. In order to demonstrate the efficacy of the proposed algorithm, Patterson’s test suites are worked out. This study aims at developing an alternative and more efficient optimization methodology and opening the application of variants of artificial immune system for solving the RCPSP.     

Optimization-based scheduling for the single-satellite,multi-ground station communication problem

In this paper, we develop models and algorithms for solving the single-satellite, multi-ground station communication scheduling problem, with the objective of maximizing the total amount of data downloaded from space. With the growing number of small satellites gathering large quantities of data in space and seeking to download this data to a capacity-constrained ground station network, effective scheduling is critical to mission success. Our goal in this research is to develop tools that yield high-quality schedules in a timely fashion while accurately modeling on-board satellite energy and data dynamics as well as realistic constraints of the space environment and ground network. We formulate an under-constrained mixed integer program (MIP) to model the problem. We then introduce an iterative algorithm that progressively tightens the constraints of this model to obtain a feasible and thus optimal solution. Computational experiments are conducted on diverse real-world data sets to demonstrate tractability and solution quality. Additional experiments on a broad test bed of contrived problem instances are used to test the boundaries of tractability for applying this approach to other problem domains. Our computational results suggest that our approach is viable for real-world instances, as well as providing a strong foundation for more complex problems with multiple satellites and stochastic conditions.