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71.
针对建设项目追求质量最优、工期最短、费用最低、资源使用最均衡并体现出安全施工和工程风险信息的目标,从灰色关联的基本原理出发,通过计算网络计划中各可行方案与虚拟最优方案的安全、质量、费用、工期集成的灰色关联度,得出方案的优劣排序,对工程项目管理具有实际的应用价值. 相似文献
72.
海岛是一种独特的生态系统, 由于其特殊的水文地质条件, 水资源相对比较贫乏, 一般都依靠地下水维持岛上生产生活用水, 如果地下水质受到影响, 则会带来较大的风险。岛内地表淡水湖泊水体污染严重。为了解决岛内地表淡水湖泊水体污染问题, 决定调用海水对其进行稀释, 而这一方案则有可能造成引水工程沿线海水侵入地下水问题。本文采用有限元方法分析从厦门西侧的筼筜湖经松柏湖调水到钟宅湾对周围地下水质和湖库水体的影响, 以及在丰水年和枯水年湖库水体和海水水体之间的补给关系。分析表明: 工程在一年左右对周围地下水的影响将趋于稳定, 工程沿线150~800m 范围内地下水的盐度产生了明显变化。在枯水年, 由于地下水位下降, 海水有可能会补给湖库, 引起湖泊盐度升高, 对工程沿线特别是饮用水备用水源湖边水库造成潜在的威胁。 相似文献
73.
R.A. Bowman 《Annals of Operations Research》2001,102(1-4):39-48
A metric pair for assessing the importance of activities in stochastic activity networks based on completing a project on time (or reaching other project milestones) is presented. The metric pair is recommended as a supplement to other metrics of activity importance that have been suggested for use with Monte Carlo simulation. The differences in behavior of the various metrics are analyzed to help understand the additional types of insights that would be available by including the new metrics in simulation-based analyses. 相似文献
74.
Mario Vanhoucke Erik Demeulemeester Willy Herroelen 《Annals of Operations Research》2001,102(1-4):179-196
In this paper we study the resource-constrained project scheduling problem with weighted earliness–tardinesss penalty costs. Project activities are assumed to have a known deterministic due date, a unit earliness as well as a unit tardiness penalty cost and constant renewable resource requirements. The objective is to schedule the activities in order to minimize the total weighted earliness–tardinesss penalty cost of the project subject to the finish–start precedence constraints and the constant renewable resource availability constraints. With these features the problem becomes highly attractive in just-in-time environments.We introduce a depth-first branch-and-bound algorithm which makes use of extra precedence relations to resolve resource conflicts and relies on a fast recursive search algorithm for the unconstrained weighted earliness–tardinesss problem to compute lower bounds. The procedure has been coded in Visual C++, version 4.0 under Windows NT. Both the recursive search algorithm and the branch-and-bound procedure have been validated on a randomly generated problem set. 相似文献
75.
Joanna Józefowska Marek Mika Rafał Różycki Grzegorz Waligóra Jan Weglarz 《Mathematical Methods of Operations Research》2000,52(3):489-499
In this paper a discrete-continuous project scheduling problem is considered. In this problem activities simultaneously require
discrete and continuous resources. The processing rate of each activity depends on the amount of the continuous resource allotted
to this activity at a time. All the resources are renewable ones. The activities are nonpreemtable and the objective is to
minimize the makespan. Discretization of this problem leading to a classical (i.e. discrete) project scheduling problem in
the multi-mode version is presented. A simulated annealing (SA) approach to solving this problem is described and tested computationally
in two versions: with and without finding an optimal continuous resource allocation for the final schedule. In the former
case a nonlinear solver is used for solving a corresponding convex programming problem. The results are compared with the
results obtained using SA for the discrete-continuous project scheduling problem where the nonlinear solver is used for exact
solving the continuous part in each iteration. The results of a computational experiment are analyzed and some conclusions
are included. 相似文献
76.
A branch-and-bound algorithm for the resource-constrained project scheduling problem 总被引:7,自引:0,他引:7
We describe a time-oriented branch-and-bound algorithm for the resource-constrained project scheduling problem which explores
the set of active schedules by enumerating possible activity start times. The algorithm uses constraint-propagation techniques
that exploit the temporal and resource constraints of the problem in order to reduce the search space. Computational experiments
with large, systematically generated benchmark test sets, ranging in size from thirty to one hundred and twenty activities
per problem instance, show that the algorithm scales well and is competitive with other exact solution approaches. The computational
results show that the most difficult problems occur when scarce resource supply and the structure of the resource demand cause
a problem to be highly disjunctive. 相似文献
77.
A noise reduction method based on weighted manifold decomposition is proposed in this paper, which does not need knowledge of the chaotic dynamics and choosing number of eigenvalues.The simulation indicates that the performance of this method can increase the signal-to-noise ratio of noisy chaotic time series. 相似文献
78.
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