Heuristic scheduling of resource-constrained projects with cash flows

Resource-constrained project scheduling with cash flows occurs in many settings, ranging from research and development to commercial and residential construction. Although efforts have been made to develop efficient optimal procedures to maximize the net present value of cash flows for resource-constrained projects, the inherent intractability of the problem has led to the development of a variety of heuristic methods to aid in the development of near-optimal schedules for large projects. This research focuses on the use of insights gained from the solution of a relaxed optimization model in developing heuristic procedures to schedule projects with multiple constrained resources. It is shown that a heuristic procedure with embedded priority rules that uses information from the revised solution of a relaxed optimization model increases project net present value. The heuristic procedure and nine different embedded priority rules are tested in a variety of project environments that account for different network structures, levels of resource constrainedness, and cash-flow parameters. Extensive testing with problems ranging in size from 21 to 1000 activities shows that the new heuristic procedures dominate heuristics using information from the critical path method (CPM), and in most cases outperform heuristics from previous research. The best performing heuristic rules classify activities into priority and secondary queues according to whether they lead to immediate progress payments, thus front loading the project schedule. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44: 365–381, 1997     

不同流量的复杂保障网络抗毁性仿真分析

通过引入流量强度指数和流量分布指数,建立了不同网络流量下的复杂保障网络级联失效抗毁性模型。基于该模型比较分析了无标度网络、随机网络和复杂保障网络在不同流量强度和流量分布下对单个节点的随机失效和故意攻击的抗毁性。结果表明:复杂保障网络的抗毁性随着流量强度的增加急剧下降。此外,流量分布对复杂保障网络的抗毁性也有显著影响。     

基于GAHP的作战决策方案优选模型

优选科学合理的作战方案,是指挥员作战决策的关键。根据作战实际情况,运用五标度和六标度法量化了各因素对作战决策方案的影响指标,建立了基于多人层次分析法(GAHP)理论的优选作战决策方案数学模型,以从方案中选出作战效益最好、付出代价最小且最具可行性的方案,作为决策的具体行动依据。最后通过实例验证了模型的可操作性。GAHP方法能很好地运用不同决策者对方案的不同评价,形成最终决策,对作战指挥决策有一定的现实意义。     

一类二阶微分方程Poincaré分岔极限环的不存在性

讨论一类二阶微分方程x¨+εf(x,x.)x.+g(x)=0的Poincar分岔极限环的不存在性,利用一阶Mel’nikov函数直接从整体上进行分析讨论,得出了若干充分条件和判别准则。     

广义Liénard方程Poincaré分岔极限环的唯一性和不存在性

讨论了一类广义Linard方程x¨+f1(x)x.2+εf2(x)x.+g(x)=0的Poincar分岔极限环的唯一性和不存在性。将不对Abel积分进行分项,而是利用一阶Mel′nikov函数直接从整体上进行分析讨论,得出了若干判别准则和充分条件。     

Production planning with resources subject to congestion

A fundamental difficulty in developing effective production planning models has been accurately reflecting the nonlinear dependency between workload and lead times. We develop a mathematical programming model for production planning in multiproduct, single stage systems that captures the nonlinear dependency between workload and lead times. We then use outer linearization of this nonlinear model to obtain a linear programming formulation and extend it to multistage systems. Extensive computational experiments validate the approach and compare its results to conventional models that assume workload‐independent planning lead times. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009     

基于PJ模型的雷达探测距离预报方法

雷达波在近海面大气中传播时受到各种因素的影响,尤其是在蒸发波导条件下,电磁波的传播路径会被显著改变,使雷达的探测距离增大形成超视距探测.给出了PJ模型的计算公式,同时叙述了基于PJ蒸发波导模型对雷达探测距离进行预测的流程,并且运用X波段雷达与海上目标进行验证,结果显示预测方法结果与实测数据比较吻合.     

模糊理论与D-S理论在指控系统目标识别融合中的应用

多传感器信息融合技术已获得了普遍的关注和广泛的应用,其理论和方法已成为智能信息处理的一个重要领域,模糊理论与证据理论(D-S)是主要的技术之一.在某试飞指控系统中,为了获得可靠的识别结果需要目标识别的融合问题.系统的从实际出发提出了基于模糊理论与D-S理论的目标识别融合方法.仿真计算结果表明,该模型和方法具有方法简单、运算量小和识别结果可靠等优点,具有一定的理论意义和使用价值.     

舰船空调系统不同保障模式的效费分析

分析了舰船全寿命期和使用期的结构,在此基础上,借助于WSEIAC模型,分别对舰船空调系统在两种保障方式的全寿命使用期效能和费用的各个指标进行了建模,提出了指标计算的思路与计算方法.结合海军舰船特点,在对WSEIAC效能模型进行修改和完善的基础上,给出了计算示例,结果显示了海军舰船空调系统采用岸基保障方式的合理性和优越性.