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121.
作为全球唯一的超级大国,美国在空间观测方面具有勿庸置疑的优势。介绍了美国现有成像侦察卫星的构成、作用和发展现状,指出了美军开始注重利用商业遥感图像的新趋势,并且详细介绍了当前美国成像卫星软件的商业开发以及美国未来天基雷达计划的发展。 相似文献
122.
孙风军 《兵团教育学院学报》2009,19(3):40-42
詹森(Jensen)不等式是解决不等式问题的一个重要方法,也是发现数学问题的重要手段。运用詹森不等式的关键是通过观察所给代数式的函数特征,构造一个凹或凸的函数,以利解题。 相似文献
123.
程序控制流图不能表示DA交互发生点处实际执行的SQL语句,因而不能清晰地表示出程序数据库的交互过程。针对该问题提出了用有限状态自动机表示DMLSQL语句,根据自动机的运行过程确定交互语句使用或定义的数据对象,并利用此信息生成表示交互语句的结点,以扩展CFG。实验表明,经过扩展后的ECFG能够直观地表示DA程序中与数据库的交互结构。 相似文献
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Trade-in programs have been widely adopted to enhance repeat purchase from replacement customers. Considering that a market consists of replacement and new segments, we study the joint and dynamic decisions on the selling price of new product (hereafter, “selling price”) and the trade-in price involved in the program. By adopting a vertical product differentiation choice model, we investigate two scenarios in this paper. In the base model, the manufacturer has sufficiently large production capacity to fulfill the customer demand. We characterize the structural properties of the joint pricing decisions and compare them with the optimal pricing policy under regular selling. We further propose a semi-dynamic trade-in program, under which the new product is sold at a fixed price and the trade-in price can be adjusted dynamically. Numerical experiments are conducted to evaluate the performance of the dynamic and semi-dynamic trade-in programs. In an extended model, we consider the scenario in which the manufacturer stocks a batch of new products in the beginning of the selling horizon and the inventory cannot be replenished. Following a revenue management framework, we characterize the structural properties with respect to time period and inventory level of new products. 相似文献
126.
We consider a design problem for wastewater treatment systems that considers uncertainty in pollutant concentration levels at water sources. The goal is to optimize the selection of treatment technologies and pipeline connections, so that treated wastewater can achieve specified effluents discharge limits as well as possible. We propose a new two-stage model to optimize a set of guarantee levels, that is, the maximum concentration level of source pollutants for which treated wastewater can be compliant with discharge limits. In the first stage, treatment technologies and pipeline connections are selected. In the second stage, when pollutant concentration levels are revealed, wastewater distribution and mixing are determined. A key attractiveness of the proposed guarantee rate optimization model is that it can be simplified into a single-stage mixed-integer linear program. In our numerical experiments based on real-world pollutants data, the guarantee rate model demonstrates its advantages in terms of computational efficiency, scalability and solution quality, compared with the standard probability maximization model. Finally, the methodology proposed in this paper can also be applied to other two-stage problems under uncertainty with similar uncertainty characteristics. 相似文献
127.
Jon Strandquist 《Small Wars & Insurgencies》2017,28(2):337-360
Foreign policy program transfer, the shifting of implementation responsibility for a foreign policy program from one organization to another, is a ubiquitous, yet under-studied, counterinsurgency phenomenon. This article conceptually develops program transfer as an important object of study; analyzes, using archival sources, an empirical case of program transfer, Operation Switchback, drawn from US counterinsurgency practice in South Vietnam; and formulates two preliminary theoretical claims related to program transfer: (1) transferred programs will tend to be altered in accordance with the characteristics of the gaining organization, and (2) program transfer may act as a signal or early-warning indicator of foreign policy change. 相似文献
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When the US Air Force set out to acquire a new aerial tanker (the KC-X), two highly suitable alternatives were offered. What could have been a short and simple source selection turned into a prolonged embarrassment. The original selection of 100 leased KC-767s was made in May 2003. But the KC-46 is expected to be operational in 2017 – more than a decade later. Our primary purpose here is to narrate and explain key events in the KC-X program. We search for useful paradigms, based in part on the US Government being better viewed as a quarrelsome committee than a monopsonist. In addition, we consider what this case might tell us about the US defense acquisition system. 相似文献
130.
SBM是支持操作级并行的一种有效的同步机制。文中基于SBM对结点调度和barrier插入算法进行了深入的研究,提出了一套有效的开发操作级并行的方案。用一有向图G(N,A)表示指令之间的相关关系,并以结点的临界路径为关键字将结点从小到大进行排序。按照排序后的结点顺序,描述了一种分配算法,将结点分配给各处理机。同时,描述了相关结点之间的barrier插入算法。 相似文献