基于遗传算法的BT项目分包商选择模型

为控制BT项目分包商随机完工时间风险,研究在满足BT项目效益和子项目逻辑关系约束的条件下,使项目完工概率最大的分包商选择问题.基于总承包人收益最大对分包人工期的激励决策,基于计划评审法描述各子项目逻辑关系约束,在计划评审法的基础上引入遗传算法对问题进行求解,最后通过实例计算分析关键线路及对应分包商的选择,研究结果为随机情况下的施工项目分包商挑选问题提供了一种有效的管理工具.     

基于系统双重风险共担的多项目鼓缓冲设置研究

为了提高关键链多项目缓冲管理的效率,首次提出了一种基于多项目双重风险共担的鼓缓冲设置方法。新方法从系统角度分析了多项目不同层级的风险共担作用,以同时落在在子项目关键链和多项目系统关键链上的系统关键活动工期占比为切入点对缓冲进行分层管理,抽取部分项目缓冲集中到系统层面,同时综合考虑风险独立因子以及鼓活动有效产出影响指数对鼓缓冲进行了定量设置。仿真结果表明,本文方法在多项目按时完工率、项目缓冲平均消耗率、系统关键链上鼓活动平均延误百分比、多项目系统总工期和成本这几个绩效方面的表现更优,提高了多项目系统的风险应对能力。     

基于物元可拓法的轨道交通PPP项目风险评价研究

风险评价是风险控制的前提,风险控制对项目成功实施至关重要.文章通过文献查阅和专家访谈梳理了PPP(Public-Private-Partnership)项目风险,建立涵盖37条指标的轨道交通PPP项目风险指标体系,构建基于物元可拓法的风险评价模型,以呼和浩特轨道交通PPP项目为例,对其项目风险进行了评价,提供一种PPP项目风险事前事中评价的方法,给项目相关方的项目风险评价和管理提供参考.     

系统动力学在建设工程风险识别中的应用

首先根据建设工程建设程序,提出了建设工程建设阶段的风险管理.简单综述了系统动力学在项目管理中的应用,然后选取在项目实施期间,以项目承包商的视角,应用系统动力学方法对项目进行风险识别.由于篇幅所限,仅以工期风险为例,详细识别了造成工期风险的原因和风险发生后引起的后果,以及风险发生后通过系统内部调节后对自身的影响,证明了系统动力学在风险识别阶段应用的可行性和优越性.     

施工项目中设计风险元传递模型研究

针对设计变更对项目实施的影响,本文将影响施工项目的设计变更原因称为项目的设计风险元,基于广义项目风险元传递理论建立系统动力学模型,动态研究设计风险元传递过程。通过模型模拟分析不同时间、不同程度的设计风险元对项目工期和项目费用影响程度,当设计风险元发生后,设计审批及设计过程将影响项目工期;受施工工序影响设计风险元造成实际施工速度不饱和,使得施工效率低下形成窝工;由于设计风险元导致的返工造成施工项目的工期延误和成本超支。此模型为风险管理者或项目管理者在设计风险管理方面提供了有力依据。     

基于复杂网络的并联式项目群结构脆弱性评估

运用复杂网络研究并联式项目群的结构脆弱性。将项目群中的任务用节点表示、任务之间的依赖关系用边表示,依据任务的工期确定点权、任务之间的依赖强度确定边权,则并联式项目群被抽象为一个有向加权网络。在分析并联式项目群网络拓扑特征的基础上,构建并联式项目群脆弱性评估模型,并对一个并联式项目群进行脆弱性评估。仿真结果表明该方法可以对并联式项目群脆弱性进行定量化评估、能够有效识别结构中的脆弱环节。本研究为保障项目群顺利实施、抵御风险提供了新的思路。     

基于工期-成本综合效用最大的关键链项目缓冲确定

为提高关键链中工期和成本的综合效用,研究一种基于关键链工期和成本进行双目标优化的缓冲确定方法。首先,该方法考虑项目不同工序间工期和成本之间的关系,并基于工期和成本的风险暴露度确定权重,解决不同工序间工期和成本偏好难以量化的问题;其次,根据权重多效用函数对工期和成本进行归一化处理,并确定综合效用最大情况下不同工序的最佳工期;最后基于尾部集中法确定项目缓冲。通过蒙特卡洛模拟实验,将此方法提取缓冲后的项目实际综合效用与传统方法进行比较。比较结果显示,该方法极大地提高项目中工期和成本的综合效用,并且对项目工期和成本均形成更有效的保护。     

基于随机活动工期的现金流动态均衡前摄性与反应性项目调度优化

承包商的现金流动态均衡对不确定条件下项目的顺利实施有重要影响。作者研究基于随机活动工期的现金流动态均衡前摄性及反应性项目调度问题,目标是在随机活动工期条件下,为承包商生成现金流均衡基准进度,并根据执行过程中的实际情况,动态地对其进行反应性调整。首先,通过建立前摄性调度优化模型生成基准进度,并提出两个反应性调度策略对其进行调整。其次,为以上诸模型的求解设计了模拟退火和禁忌搜索相结合的混合算法tabu-SA。最后,针对前摄性调度模型,在随机生成的算例集合上对算法进行测试,并进行大规模仿真实验。研究结果可以为随机活动工期下承包商保持现金流动态均衡、确保项目顺利实施,提供定量化决策支持。     

中国制造业实施六西格玛管理的成功关键要素分析

自摩托罗拉公司于1987年提出六西格玛概念以来,六西格码管理已逐渐成为质量改进的主流方法之一。尽管不少学者和咨询专家对实施六西格玛管理的成功关键要素进行了探讨,但都是基于理论分析或定性描述。本文在综述国内外相关研究文献的基础上,提出了实施六西格玛管理的成功要素概念模型,并通过调查问卷和利用结构方程模型,对中国制造业实施六西格玛管理的关键成功要素进行了实证分析。研究结果表明:领导层的高度关注,建立并实施合适的六西格玛战略,以顾客和市场为关注焦点,并通过有效的成果测量、评价和奖励方法,选择、管理和实施六西格玛项目是实施六西格玛管理的关键成功要素;同时,本文也分析了这些要素之间的因果关系。     

PPP项目全生命周期三维风险动态分析模型

在PPP项目全生命周期中如何识别、评估和分担风险,已成为PPP项目能否成功实施的关键.基于全生命周期理论,借鉴霍尔的三维结构模型,以多维度、动态分析视角构建PPP项目全生命周期三维风险动态分析模型,并以东部地区某地下综合管廊PPP项目为例进行计算与分析,实现各方利益均衡和综合效用最大化.通过实例论证了模型构建的正确性以及风险分担的科学性和可操作性,对当前我国PPP项目持续稳健发展具有参考借鉴作用.     

A fuzzy random periodic review system with variable lead-time and negative exponential crashing cost

In the present model a fuzzy random periodic review system has been investigated with the annual demand assumed to be a discrete fuzzy random variable with associated imprecise probabilities. Keeping in mind the widespread application of the Just-In-Time manufacturing philosophy and lead-time management being one of its most effective methods of implementation, the lead-time has been assumed to be an added control parameter. Also as it may not be always possible to resolve the lead-time into all its components and estimate their individual crashing costs, the crashing cost has been introduced as a negative exponential function of the lead-time. A methodology has been developed in this regard such that the total inventory cost is minimized and the optimal period of review, the optimal target inventory level and the optimal lead-time are determined in the process. An algorithm has been provided to encapsulate the methodology and it has been illustrated by way of a numerical example.     

企业自主研发与合作创新的风险测度及组合优化

企业在整合内部创新要素进行自主研发的同时,也会寻求外部创新资源进行合作创新,当前同时从事多个R&D项目已成为常见的企业经营活动,如何在不确定条件下分析多个R&D项目投资的策略选择及风险优化,对于企业的长期发展具有重要意义。根据企业是否采取合作创新策略,可将其R&D项目分为自主研发与合作创新两类,以项目的研发成功率和投资收益率代表技术风险和市场风险,分别测度自主研发与合作创新项目的风险特性,并在此基础上构建企业R&D项目投资组合优化模型,以在自主研发与合作创新项目之间进行权衡取舍。结果表明,企业对于自主研发与合作创新项目投资组合的最优投资权重,主要取决于这两类组合的期望收益率、收益率方差、期望成功率以及两组合之间的协方差。企业可基于关键参数制定出最优的R&D项目投资组合选择策略,合理分配资金以达到风险最小化的投资目标。     

Weather Risk in Offshore Projects

Risk analysis tools have been used to help manage various projects. This paper describes a case study in which an extension to the stochastic project network model was developed for a risk analysis of an oil platform installation, quantifying the possible impact of the weather on the project's schedule. Examination of the weather data suggested the use of a Markov weather model combined with a separate residence time distribution for key states. The weather model was incorporated into the stochastic project network allowing the interactions of the various project uncertainties to be examined. While the weather introduced a significant additional risk to the project, analysis of management's options indicated that much of the risk might be avoided. In particular, the analysis quantified the benefits of scheduling the project start to take advantage of the seasonal variations and hiring heavy duty equipment to operate in more arduous conditions.     

基于活动延期风险加权时差的资源受限项目调度鲁棒性度量

在项目调度鲁棒性研究中,当活动出现延期风险时,由于各活动性质不同,其延期风险权重也不同,权重越大的活动越有可能影响项目的完工时间。针对资源受限项目调度问题,提出一个基于活动延期风险加权时差的鲁棒性度量新指标。在出现不确定因素干扰时,该指标不仅考虑了活动延期风险权重的影响,同时为实现时差在多个任务之间的共享,还考虑了紧前任务数量的影响。建立一个以加权时差最大化为目标的资源受限项目调度鲁棒优化模型,并针对模型特点,设计了基于禁忌搜索的模拟退火算法。最后,通过算例验证了该度量方式和算法的合理性和有效性,对比分析结果表明所提出的指标优于现有的度量指标,较好地满足了项目调度质量鲁棒性的要求。     

An investigation of lead-time effects in manufacturing/remanufacturing systems under simple PUSH and PULL control strategies

In this paper we extend the PUSH and PULL control strategies defined by van der Laan et al. (E.A. van der Laan, M. Salomon, R. Dekker, Production planning and inventory control for remanufacturable durable products, Working paper 9531/A, Econometric Institute, Erasmus University Rotterdam, The Netherlands, 1995) to evaluate numerically the effects of lead-time duration and lead-time variability on total expected costs in production/inventory systems with remanufacturing. Although both strategies are non-optimal, they are relatively easy to analyse numerically and, more importantly, they are actually used in practice. The most important outcomes of the study are, that for both control strategies: (i) manufacturing lead-times have a larger influence on system costs than remanufacturing lead-times; (ii) a larger remanufacturing lead-time may sometimes result in a cost decrease; and (iii) a larger variability in the manufacturing lead-time may sometimes result in a cost decrease.     

Manufacturing lead-time rules: Customer retention versus tardiness costs

Inaccurate production backlog information is a major cause of late deliveries, which can result in penalty fees and loss of reputation. We identify conditions when it is particularly worthwhile to improve an information system to provide good lead-time information. We first analyze a sequential decision process model of lead-time decisions at a firm which manufactures standard products to order, and has complete backlog information. There are Poisson arrivals, stochastic processing times, customers may balk in response to quoted delivery dates, and revenues are offset by tardiness penalties. We characterize an optimal policy and show how to accelerate computations. The second part of the paper is a computational comparison of this optimum (with full backlog information) with a lead-time quotation rule that is optimal with statistical shop-status information. This reveals when the partial-information method does well and when it is worth implementing measures to improve information transfer between operations and sales.     

Optimal and heuristic lead-time quotation for an integrated steel mill with a minimum batch size

This paper presents a model of lead-time policies for a production system, such as an integrated steel mill, in which the bottleneck process requires a minimum batch size. An accurate understanding of internal lead-time quotations is necessary for making good customer delivery-date promises, which must take into account processing time, queueing time and time for arrival of the requisite volume of orders to complete the minimum batch size requirement. The problem is modeled as a stochastic dynamic program with a large state space. A computational study demonstrates that lead time for an arriving order should generally be a decreasing function of the amount of that product already on order (and waiting for minimum batch size to accumulate), which leads to a very fast and accurate heuristic. The computational study also provides insights into the relationship between lead-time quotation, arrival rate, and the sensitivity of customers to the length of delivery promises.