基于价值流优化的项目组合网络引力模型

在构建项目组合网络时,除了考虑构建网络所需的成本、网络的效率外,同时还要考虑网络节点间的价值流(项目间的价值传递)因素,例如,当计划增加一个新项目时,组织除了考虑该项目的自身价值,还要考虑该项目进入到项目组合中产生的增值价值,即1+12的项目间协同价值,这个协同价值在网络中是通过网络节点间的价值流来体现的.构建项目组合网络的根本目的是实现网络上的动力学,只有两节点间有信息交互的需求,两节点的连边才有意义.从优化项目组合网络效益的角度出发,引入预期价值流这一概念,提出基于预期价值流优化的项目组合网络的引力模型,并详细分析该模型的拓扑结构特性、权度相关性,并利用引力模型与实际的项目组合网络进行了比较,所有的特征误差都很小,模型不仅能够定性地刻画真实项目组合网络中的各种特性,而且还能定量地得到具体项目组合网络的统计分布.     

网络计划的最低成本日程研究

网络计划优化的一个重要内容是研究项目的最低成本日程。本文假定工序在可压缩范围内,直接成本呈线性变化的前提下,以线性规划为工具,提出了一种最低成本日程的优化方法。当借助计算机求解时,该方法更加简单实用。     

基于粒子群算法的大型网络计划资源优化

现有求解网络计划资源优化的方法中,解析法不能解决大型复杂网络优化问题,启发式方法过多依赖具体问题、求解效率低,遗传算法生成新一代优化解种群依据的三个算子的实现参数选择,大部分依靠经验并严重影响解的品质,粒子群算法存在大型网络计划资源优化计算量过大和缺少大型网络计划资源优化算例问题.借助设计网络计划时间参数的计算机算法、建立评价函数、设计进化方程等基础工作,选择与工作开始时间相关的变量作为粒子空间位置,用蒙特卡洛方法和限制条件优化初始粒子群,设置可行解范围,用二维动态数组解决大型网络计划资源优化运行image超限问题,通过粒子群算法进化,寻求大型网络计划资源优化解,算例表明基于粒子群算法的大型网络计划资源优化效果明显,粒子群算法参数分析表明:粒子群算法的参数会影响网络计划资源优化结果,而且初始粒子群限制条件和优化目标设置的影响程度较大.     

从一个编制计划的案例说网络计划法

网络计划法是以网络图反映、表达计划安排,据以选择最优工作方案,组织协调和控制生产(项目)的进度(时间)和费用(成本),使其达到预定目标,获得更佳经济效益的一种优化决策方法.     

求解CPM网络计划的最大网络时差

CPM网络计划的网络时差表示项目中各工序实际可使用的机动时间的总和(绝非理论上机动时间的简单加总),即CPM网络计划的总机动时间,它决定着在总工期不变的前提下,所有工序实际可以达到的最大工期的总和,与项目的成本管理和时间管理密切相关。网络时差是变量,取决于各工序的时间进度安排,说明可以通过调整工序的时间进度来决定该时差的取值,特别是其最大值,进而实现成本和时间优化。本文首先从新的角度分析了网络时差的含义;然后,在此基础上设计了求解最大网络时差的算法,其思路为,通过建立和分析最大网络时差模型,将其转化为特殊的“时间-费用权衡问题”,进而可运用Fulkerson算法等经典算法求解;最后,通过应用举例对该算法进行了演示。     

用线性规划方法求网络计划的最低成本日程

网络计划优化的一个重要内容是研究项目的最低成本日程。本文假定工序在可压缩范围内,直接成本呈线性变化的前提下,以线性规范为工具,提出了一种最低成本日程的优化方法。当借助计算机求解时,该方法更加简单实用。     

九州通线下药店选址优化问题研究

针对九州通的020业务销售模式,研究了基于多枢纽站多分派网络的实体药店选址优化问题.以现有药店为备选点,每天的药店运行成本和物流成本之和极小化为目标,建立了实体药店选址优化问题的混合整数规划模型,利用Lingo软件编程求解得到优化以后的实体药店选址方案.通过与现有的实体药店选址方案对比发现,在不改变实体药店覆盖半径的前提下,优化后实体药店的数量从9家减少为4家,每天的药店运行成本和药品配送成本之和大约降低14万元,占药品物流总成本的32%.研究结果为九州通医药公司优化线下药店的配送网络提供了理论依据.     

工程网络计划时间——费用分析的模糊规划

初始的网络计划不一定是最优的,甚至不是一个可行的网络计划,在时间或成本等方面可能存在着一些矛盾和不足,必须通过网络计划的优化方法来加以完善与解决。目前较常用的网络计划优化方法是参数线性规划,它综合地考虑了时间,费用等因素。但使用这种方法时,必须准确地知道工作最短延续时间,工作正常延续时间,总工期及有关费用等,而在实际工程中,由于各种因素影响(人员的变动,成本的波动等,)特别是面临一项新的工程时,往往无法确切地定出模型中参数所需要的量值,只能给出参数量值大致可能的范围,这就需要将一般的参数线性规划拓展为模糊规划。本文在参数线性规划的基础上对工程网络计划时间——费用分析实行模糊规划,并在计算机上调试运行成功,取得了较满意的效果。计算的结果表明,工程网络时间——费用分析模糊规划的优化结果使计划者获得了更充分的决策余地。     

基于灰色系统理论多资源网络计划分配的优化方法

本文在分析了现有的网络资源分配的几个优化准则和在工序排序过程中各种因素对工期产生影响的基础上，基于灰色系统理论，提出了以关联度为工序优先级的多资源网络计划分配问题的优化准则，并通过算例和与其它优化准则对比分析，说明依据该准则可使网络计划满足多资源约束条件，并使工期延长最少     

挣值法的参数扩展与修正研究

传统挣值法基于确定性与稳定性的项目基准计划,仅考虑和集成了项目时间与项目成本两个参数(要素),忽略了货币的时间价值.针对这些不足,对其进行参数扩展和相关的修正:运用蒙特卡罗法制定具有不确定性的项目的基准计划,考虑和集成了项目范围与项目质量两个参数,将时间因素引入成本度量中.在此基础上,提出和定义了挣值法的有关指标,以期提高挣值法的集成度和准确度.     

安全质量费用工期在网络计划中的系统优化研究

施工网络计划中安全、质量、费用、工期达到综合优化是工程管理决策追求的目标,在工程项目管理中对这4个指标进行全面系统分析,并且进行综合均衡优化,对于提高工程项目的综合效益至关重要.采取在网络计划所有可行的施工方案中寻求最优的方案组合,从而达到总目标的优化.并且通过一个实例来说明本方法的应用.     

A modified active set algorithm for transportation discrete network design bi-level problem

Transportation discrete network design problem (DNDP) is about how to modify an existing network of roads and highways in order to improve its total system travel time, and the candidate road building or expansion plan can only be added as a whole. DNDP can be formulated into a bi-level problem with binary variables. An active set algorithm has been proposed to solve the bi-level discrete network design problem, while it made an assumption that the capacity increase and construction cost of each road are based on the number of lanes. This paper considers a more general case when the capacity increase and construction cost are specified for each candidate plan. This paper also uses numerical methods instead of solvers to solve each step, so it provides a more direct understanding and control of the algorithm and running procedure. By analyzing the differences and getting corresponding solving methods, a modified active set algorithm is proposed in the paper. In the implementation of the algorithm and the validation, we use binary numeral system and ternary numeral system to avoid too many layers of loop and save storage space. Numerical experiments show the correctness and efficiency of the proposed modified active set algorithm.     

A Linear Model for Estimating Project Resource Levels and Target Completion Times

Selecting target completion time and appropriate resource availabilities for projects is not easy. In this paper a simple relationship is established to aid the planner in this task. The relationship is based on experiments involving 4942 different network/resource configurations. The relationship can be used to select the best balance between the cost of over-runs and the cost of resources.     

项目组合网络实证研究

将复杂网络理论引入到项目组合管理中,以项目为节点,以项目之间的依赖关系为边,项目的成本看作点权,项目之间的依赖强度看作边权,将项目组合抽象为一个复杂加权网络。研究了4家企业的项目组合网络,在分析项目组合特性的基础上,概括了项目组合的复杂网络行为特征。对企业项目组合网络进行综合对比分析发现,项目组合网络具有如下相似特征:①节点度分布不同于其他社会网络,倾向于幂律分布,又有偏斜泊松分布的迹象;②度相关系数负相关,有别于其他社会网络;③具有集群结构;④聚集系数很大;⑤网络直径较小;⑥平均度数小于4。     

An optimal repeat inspection plan with several classifications

Multicharacteristic critical components exist in many systems. Such components could be a part of an aircraft, space shuttle or a gas ignition system. A component is critical if it causes disaster or a very high cost upon failure. In this paper, a new inspection plan for critical multicharacteristic components is presented. A mathematical model that depicts the plan is developed. An algorithm is proposed for finding the optimal number of repeat inspections and the sequence of characteristics for inspection that minimizes expected total cost per accepted component. The expected cost consists of the cost of inspection and the cost of misclassifications. The inspection plan and the model developed generalize existing models in the literature and provide a more realistic formulation. An example is given to demonstrate the plan and the model.     

Uncertainty Modelling in Software Development Projects (With Case Study)

A project scheduling model tailored specifically for software development projects is proposed in this study. The model incorporates uncertainties related to activity durations and network topology. The first type of uncertainty exists due to error-prone coding which might result in elongated task durations caused by validation and debugging sessions. Furthermore, in practice, macro-activities represent groups of sub-tasks in order to simplify the planning and monitoring of the project. Due to the aggregation, it is more difficult to be precise on the duration of a macro-activity.The uncertainty related to the network topology is due to common database design issues or program modules shared among parallel tasks in the project network. These tasks become associated with each other through uncertain Start-to-Start (SS) precedence relationships. On the other hand, SS lags may also be the outcome of technological precedence relationships among pairs of activities. However, the imprecision underlying the work content of a predecessor activity leads to uncertain SS lags.Software development projects are human-intensive projects and hence, the duration of a task depends on the skill of the person assigned to the job as well as his/her learning rate. Thus, a task may be realized by alternative staff members which results in different expected task durations. Hence, a realistic model proposed for software development projects should incorporate staff assignment features under the uncertainties discussed above. In this study, we develop a mathematical model for software development projects and propose heuristic solution methods to be used by the project co-ordinator in preparing the project plan. The heuristic algorithms developed here are tested on real data provided by a consulting firm undertaking software development projects from manufacturing companies in Turkey.     

基于实际路网情境的配送车辆调度优化

在实际路网情境下结合车道数、车道宽度、路口信号灯设置等路网物理特性,构建了考虑综合交通阻抗的多车型车辆调度模型,提出了两阶段求解策略:第1阶段设计了改进A-star精确解算法用于计算客户时间距离矩阵;第2阶段针对实际路网的特征设计了混合模拟退火算法求解调度方案。以大连市某配送中心运营实例进行路网情境仿真试验,结果表明:改进A-star算法较改进Dijkstra算法具有更短的路径搜索时间;混合模拟退火算法求解结果较实际调度方案优化了13.1% 的综合成本;路网增流、区域拥堵和路段禁行三类路网情境均能对配送方案的车辆配置、路径选择、客户服务次序、作业时间和违约费用等5方面内容产生干扰,调度计划的制定需要详细考虑这些因素的变化。     

Operations planning with VERT

The Venture Evaluation and Review Technique (VERT) is a computerized, mathematically oriented network-based simulation technique designed to analyze risk existing in three parameters of most concern to managers in new projects or ventures--time, cost, and performance. As such, the VERT technique is more powerful than techniques such as GERT, which are basically time and cost oriented. VERT has been successfully utilized to assess the risks involved in new ventures and projects, in the estimation of future capital requirements, in control monitoring, and in the overall evaluation of ongoing projects, programs, and systems. It has been helpful to management in cases where there is a requirement to make decisions with incomplete or inadequate information about the alternatives. An example describing the application of VERT to an operational planning problem--the evaluation of electric power generating methods--is illustrated.     

Choosing the Operational Research Programme for B.I.S.R.A

This paper examines some important problems in the evaluation and selection of research projects, with particular reference to operational research projects in a central industry research organization. A method for project evaluation is suggested which provides data suitable for use in a powerful and flexible formal procedure for project selection. In evaluating a project, the assessment of resource requirements is based on a probabilistic network plan of the project, and the estimates of benefits are derived from the marginal effects on the industry of performing or not performing the project, using discounted cash flow techniques. The procedure for project selection chooses not only the projects to be undertaken, but also the team sizes that should be used. A wide variety of constraints can be imposed on the system to reflect different aspects of management policy or other special factors. The procedures described have been implemented, and have proved well worth while.     

基于资源互补的项目伙伴选择方法

当不同企业承担的工程项目在同一地区同时开展时,彼此间经常会存在工程资源互补的可能,如果加以合理利用,便能够使项目的实施进一步得到优化。因此,企业如何选择有资源互补潜力的最佳合作伙伴有必要予以研究。文中从合作博弈的角度阐述了资源互补的形成机理,定性分析了伙伴选择问题的决策特征;运用双层规划构建了基于资源互补的项目伙伴选择模型,提出了基于期望收益约束选择的求解方法。最后以某临港产业园区填海项目与其他项目的资源互补为例,采用文中提出的模型及求解方法优化施工方案,得到降低建设投资、缩减施工工期的优化效果。