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提出一种以柔度为基础的具有随机刚度弯曲梁的有限元公式。在计算过程中 ,用与刚度均值有关的内力近似表示未知内力值。通过蒙特卡罗模拟可示出刚度的一维可靠性密度函数和相关函数 ,可用来估算柔度的均值和协方差函数。最后根据新的公式计算出随机梁的均值和协方差。 相似文献
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We examine several methods for evaluating resource acquisition decisions under uncertainty. Traditional methods may underestimate equipment benefit when part of this benefit comes from decision flexibility. We develop a new, practical method for resource planning under uncertainty, and show that this approach is more accurate than several commonly used methods. We successfully applied our approach to an investment problem faced by a major firm in the aviation information industry. Our recommendations were accepted and resulted in estimated annual savings in excess of $1 million (US). © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2003 相似文献
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在介绍传统过程建模方法的基础上,提出了"任务/过程"的概念,详细分析了作战飞机寿命周期过程中任务、过程的具体含义。探讨了作战飞机"任务/过程"的图形化描述方法,并将其与IDEF0建模工具结合起来建立作战飞机寿命周期过程模型,详细分析了过程模型中信息的含义,有利于对作战飞机寿命周期费用进行更加有效的控制。 相似文献
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针对反潜机使用空投鱼雷对潜实施攻击时的最优落水点问题,建立了鱼雷弹道模型、声纳自导系统发现模型、潜艇机动模型、均方差模型,对空投鱼雷对潜攻击过程进行了模拟仿真,得出了相对于不同舷角、距离的鱼雷发现概率,并确定了鱼雷的最优落水点,以期为部队合理使用空投鱼雷提供决策依据。 相似文献
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In this article we address an important class of supply contracts called the Rolling Horizon Flexibility (RHF) contracts. Under such a contract, at the beginning of the horizon a buyer has to commit requirements for components for each period into the future. Usually, a supplier provides limited flexibility to the buyer to adjust the current order and future commitments in a rolling horizon manner. We present a general model for a buyer's procurement decision under RHF contracts. We propose two heuristics and derive a lower bound. Numerically, we demonstrate the effectiveness of the heuristics for both stationary and non‐stationary demands. We show that the heuristics are easy to compute, and hence, amenable to practical implementation. We also propose two measures for the order process that allow us to (a) evaluate the effectiveness of RHF contracts in restricting the variability in the orders, and (b) measure the accuracy of advance information vis‐a‐vis the actual orders. Numerically we demonstrate that the order process variability decreases significantly as flexibility decreases without a dramatic increase in expected costs. Our numerical studies provide several other managerial insights for the buyer; for example, we provide insights into how much flexibility is sufficient, the value of additional flexibility, the effect of flexibility on customer satisfaction (as measured by fill rate), etc. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008 相似文献
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