基于优先关系的飞机机载设备维修拆卸CPN模型

现有的拆卸Petri网模型用于维修拆卸序列规划时,存在约束关系描述不准确、网系统模型结构复杂等不足.文中根据飞机机载设备维修拆卸的特点,考虑拆卸优先约束关系对拆卸时间的影响,提出了基于拆卸优先约束关系和着色网的DCPN模型.首先建立m维可拆情况下拆卸优先矩阵的生成方法,并改进其取值和表征,解决了设备间约束关系的准确描述问题;然后采用着色网建模方法简化了网系统模型.基于DCPN的可达图和有界、并发、冲突等动态特性,实现了对拆卸序列及其并发操作的自动求解.最后通过实例证明了DCPN模型以及相应的拆卸序列求解方法的正确性.     

最小分布优先Clos网路由算法

提出了一种新的Clos网无阻塞路由算法、最小分布优先算法,用该算法可以降低Clos路由算法的高时间复杂度。对于Clos网连接说明矩阵,提出并证明了矩阵中某一列的完全性问题是一个独立的问题,并据此提出了以最小分布优先的方式逐列计算Clos连接说明矩阵的策略,消除了产生在矩阵列之间的回溯以及列内元素之间的回溯,能够完全实现无阻塞路由,在最坏情况下的时间复杂度为O(N3/2),可以应用于Clos网路由控制。     

基于节点支路链矩阵的配电网动态拓扑分析方法研究与应用*

针对配电网中现有拓扑分析方法运算复杂、速度较慢、重用性较差,以及当配网规模扩大或开关状态改变时,不易及时地反映网络拓扑信息等问题,提出基于支路链矩阵的配电网动态拓扑分析方法。在系统正常运行时,采用特殊节点法将配电网划分多个支路链子图,以节点-支路链矩阵描述配网拓扑结构,借助邻接矩阵标记法与深度优先搜索原则结合完成更新后的拓扑网络的电气岛连通性分析。当支路动态变化时,根据支路属性利用方向深度优先搜索法快速地修改网络拓扑结构,局部更新节点-支路链矩阵。多个实例结果表明该方法可适应多种配电网接线结构,搜索过程中节点数量明显减少,降低了算法复杂度,提高了拓扑分析速度,为不同配网结构动态分析提供了一种有效的方法。     

基于混合覆盖网的可靠应用层组播方案

现有的应用层组播协议根据覆盖网的构建方法可分为网优先和树优先两种.提出了一种网.树混合的可靠应用层组播方案即M-THROM,该方案模型由一个核心网和多个附加树组成,包括了差错控制机制及拥塞控制机制,适合于大规模、低时延的可靠数据传输服务.仿真实验结果表明,该方案继承了网优先和树优先两种协议各自的优点,有良好的扩展性与较低的控制成本.     

基于矩阵方法的有界Petri网系统的能观性分析

Petri网和有限自动机是离散事件动态系统的两类主要研究内容.而Petri网系统的能观性分析与判别是基于Petri网的实际系统设计、优化、监测及控制的重要基础.以往关于Petri网能观测性的研究缺乏定量化的充要判别条件.本文利用代数矩阵方法研究了带有输出的有界Petri网系统的能观性问题.首先,基于矩阵的半张量积,将带有输出的有界Petri网系统的动态行为以线性方程组的形式建立了数学模型.然后,针对初始标识和当前标识,介绍了两种能观性定义.最后,基于矩阵运算建立了关于有界Petri网系统能观性的几个充分必要条件,并给出严格证明.数值算例验证了理论结果.本文提出的方法实现了有界Petri网系统能观性的矩阵运算,易于计算机实现.     

基于时空Kriging方法的时空数据插值研究

在对气象数据进行插值的过程中, 如果只考虑数据的空间信息而忽视数据在时间上的关联, 必然影响插值的精度.针对具有时空特性的气象数据, 提出一种将时空Kriging方法与弹性网方法相结合的新方法.该方法主要利用弹性网算法解决时空Kriging算法中的时空变异函数矩阵为病态矩阵而无法求逆的问题, 通过弹性网算法获得变异函数矩阵方程的稀疏解, 从而提高时空插值的精度.在实际观测的气温数据和AQI数据上的仿真实验验证了该方法对气象时空数据插值的准确性.     

基于分配系数矩阵的网损分摊方法探究

新电改"九号文"下发后,输配电成本中的网损分摊问题受到了广泛关注.为公平合理的将网损费用分摊给用户,论文提出了一种基于分配系数矩阵的网损分摊方法.首先进行全网潮流计算,得到各线路上的功率损耗;然后根据发电机对线路的分配系数矩阵计算各发电机应分摊的网损,再由发电机对负荷的分配系数矩阵计算得到各负荷应分摊的网损.最后,采用...     

着色Petri网在科技计划项目管理系统建模中的应用

在深入研究科技计划项目管理业务基础上,鉴于Petri网的特点,提出了利用着色Petri网建模科技计划项目管理系统的方法.分析了着色Petri网适合于系统建模的原因,以项目管理评审环节为例讨论了着色Petri网在建模中的应用,并建立了基于着色Petri网的系统模型.通过对该模型的分析仿真结果表明,该方法是可行和有效的.     

基于大数据调度的OMS配网一体化调控算法研究

针对当前OMS配网一体化调控方法存在的带宽利用率低、数据传输时延高和数据丢包率高的问题,提出基于大数据调度的OMS配网一体化调控算法.根据任务的稀缺度和紧急度计算任务在OMS配网中的优先请求级别,采用历史信息统计法结合节点能力影响因素计算节点在OMS配网中的上传能力.在任务优先请求级别和节点上传能力的基础上,计算路径在OMS配网中的可用带宽和前向传输时延,并将最大优先算法应用到发生数据丢包的现象中,重新选择传输路径,避免配网中接收端出现乱序的现象,根据计算结果结合重选路策略实现OMS配网的一体化调控.实验结果表明,所提算法的带宽利用率高、数据传输时延低、数据丢包率低.     

Petri网信标和陷阱计算的矩阵半张量积方法

本文基于矩阵半张量积(semi-tensor product,STP)方法研究了普通Petri网(Petri nets,PNs)信标和陷阱的计算问题.首先,利用STP方法建立了两个矩阵方程,分别称为Petri网的信标方程(siphon equation,SE)和陷阱方程(trap equation,TE).其次,证明了计算Petri网的信标和陷阱分别等价于求信标方程(SE)和陷阱方程(TE)的非零解.同时,给出了计算Petri网所有信标和陷阱的算法.最后,实例和实验结果说明了本文方法的可行性与有效性.本文所提出的方法对于Petri网信标和陷阱的计算是非常有效的,它只涉及到矩阵的乘法运算.     

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。     

带广义紧前约束的资源受限项目计划问题求解

介绍带广义紧前约束资源受限项目计划问题的约束条件和数学模型,对该问题的网络拓扑和时间约束条件进行了分析,对该问题求解的相关定义、定理、预处理过程进行了介绍,提出该问题的蚁群禁忌优化算法.     

Reactive scheduling in the multi-mode RCPSP

The multi-mode resource-constrained project scheduling problem (MRCPSP) involves the determination of a baseline schedule of the project activities, which can be executed in multiple modes, satisfying the precedence relations and resource constraints while minimizing the project duration. During the execution of the project, the baseline schedule may become infeasible due to activity duration and resource disruptions. We propose and evaluate a number of dedicated exact reactive scheduling procedures as well as a tabu search heuristic for repairing a disrupted schedule, under the assumption that no activity can be started before its baseline starting time. We report on promising computational results obtained on a set of benchmark problems.     

Fixed priority scheduling of tasks with arbitrary precedence constraints in distributed hard real-time systems

This paper considers the schedulability analysis of real-time distributed applications where tasks may present arbitrary precedence relations. It is assumed that tasks are periodic or sporadic and dynamically released. They have fixed priorities and hard end-to-end deadlines that are equal to or less than the respective period. We develop a method to transform arbitrary precedence relations into release jitter. By eliminating all precedence relations in the task set one can apply any available schedulability test that is valid for independent task sets.     

Multiprocessor scheduling of processes with release times,deadlines, precedence, and exclusion relations

The author presents a scheduling algorithm that solves the problem of finding a feasible nonpreemptive schedule whenever one exists on M identical processors for a given set of processes such that each process starts executing after its release time and completes its computation before its deadline. A given set of precedence relations and a given set of exclusion relations defined on ordered pairs of process segments are satisfied. This algorithm can be applied to the important problem of automated pre-run-time scheduling of processes with arbitrary precedence and exclusion relations on multiprocessors in hard-real-time systems     

Scheduling processes with release times, deadlines, precedence andexclusion relations

An algorithm that finds an optimal schedule on a single processor for a given set of processes is presented. Each process starts executing after its release time and completes its computation before its deadline and a given set of precedence relations and exclusion relations defined on ordered pairs of process segments are satisfied. This algorithm can be applied to the important and previously unsolved problem of automated pre-run-time scheduling of processes with arbitrary precedence and exclusion in hard-real-time systems     

Scheduling Under Common Due Date, A Single Resource and Precedence Constraints—A Dynamic Approach

This paper discusses dynamic methods for solving a class of multi-project scheduling problems in which rates of job performances are controllable and resources such as money, energy or manpower per time unit, are renewable and continuously divisible. The objective is to complete the projects as close to the common due date as possible. Two different ways of imposing sequential precedence relations between project jobs are explored by formulating two dynamic models and studying their relationships on the optimal solution. Efficient time-decomposition algorithms for finding either globally optimal schedules or lower bound guided near-optimal solutions are suggested and computationally tested.     

Combining contemporary and traditional project management tools to resolve a project scheduling problem

In this paper we examine a construction project involving the building of large concrete slabs for three buildings in an office park complex. There are finish-to-start (FS) as well as start-to-start (SS) and finish-to-finish (FF) precedence relationships among the project activities. We prepare an initial project schedule using Microsoft Project and manually validate the results using the precedence diagramming method (PDM) procedure. When the client informs us that the schedule must be shortened we find that Microsoft Project does not have the capability for resolving our particular time/cost tradeoff issues. So we revert to the traditional approach for resolving time/cost tradeoffs in projects and develop an original linear programming formulation for the time/cost tradeoff problem when a project is modeled as a precedence diagram. By combining contemporary (Microsoft Project) and traditional (a linear programming time/cost tradeoff model) project management tools we are able to successfully resolve the scheduling issues associated with the slab construction project. Further, we demonstrate the anomalous effects of start-to-start (SS) and finish-to-finish (FF) relationships via our construction project example in which the solution to the time/cost tradeoff problem requires that certain activities be lengthened in order to shorten the project duration.     

A mathematical model for the multi-mode resource-constrained project scheduling problem with mode dependent time lags

This paper presents an exact model for the multi-mode resource-constrained project scheduling problem with generalized precedence relations in which the minimal or maximal time lags between a pair of activities may vary depending on the chosen modes. All resources considered are renewable. The objective is to determine a mode and a start time for each activity so that all constraints are obeyed and the project duration is minimized. Project scheduling of this type occurs in many fields, for instance, construction industries. The proposed model has been inspired by the rectangle packing problems. In spite of the fact that it needs a feasible solution to start for conventional models, the new model has no need for a feasible solution to start. Computational results with a set of 60 test problems have been reported and the efficiency of the proposed model has been analyzed.     

协同震荡搜索混沌粒子群求解资源受限项目调度问题

针对求解资源受限项目调度问题(RCPSP),提出了协同震荡搜索混沌粒子群(CSCPSO)算法。算法围绕种群粒子吸引子建立双向协同震荡搜索机制,该机制一方面使粒子向吸引子收敛,另一方面使粒子震荡调整自身与吸引子相邻维度大小关系不一致的维度,提升算法的搜索精度和种群的多样性。项目调度采用基于粒子的拓扑排序和串行项目进度生成机制,保证项目调度解决方案满足资源约束和紧前约束。采用具体算例对算法进行检验,结果表明该算法在求解RCPSP的精度和稳定性方面表现更优。