The selection allocation problem

The Selection Allocation Problem (SAP) is a single period decision problem which involves selecting profit‐maximizing (or cost‐minimizing) activities from various distinct groups, and determining the volume of those activities. The activities in each group are selected subject to the availability of that group's resource, which is provided by either pooling or blending raw inputs from several potential sources. Imbedded in the decision process is the additional task of determining how much raw input is to be allocated to each group to form the resource for that group. Instances of this problem can be found in many different areas, such as in tool selection for flexible manufacturing systems, facility location, and funding for social services. Our goal in this paper is to identify and exploit special structures in the (SAP) and use those structures to develop an efficient solution procedure. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 707–725, 1999     

栅格地理数据并行格式转换引擎

如今大规模地理数据正在社会各个部门和组织中迅速积累,但是由于部门利益和历史沿袭等原因,大规模地理数据共享仍然极具挑战,相应共享技术需求仍然极其旺盛。作为地理数据共享的基础方式之一,传统单机地理数据格式转换技术,一方面受限于磁盘读写及带宽瓶颈,另一方面面对日趋庞大的数据规模,已很难满足实际应用需求。因此提出一种针对栅格地理数据的并行格式转换引擎,采用高性能计算集群环境支持大规模栅格地理数据转换共享,大幅降低了大规模栅格地理数据转换过程的时间成本。栅格地理数据并行格式转换引擎采用基于公共接口的设计理念,框架灵活、具有良好的扩展性,支持地理数据格式的读写自定义以及新数据格式添加,能够实现接入数据格式间的任意两两转换。为验证引擎框架及其处理效率,在Lustre并行集群环境下以格网数据交换格式(国家地理空间数据交换格式)向常见栅格地理格式的转换为示例进行了测试实验。结果表明,栅格地理数据并行格式转换引擎能够在8个节点Lustre集群中达到7.54的良好并行加速比。     

均布压力下T型连接极限承载特性试验研究

针对复合材料舵翼骨架与蒙皮连接,设计了两种T型连接结构,并对其在波浪砰击载荷作用下的极限承载特性进行了试验研究。根据结构承载特点,提取典型局部试验缩比模型,给出了均布压力下T型连接试验载荷等效方法。试验比较了两种T型连接的承载特性差异,研究了跨距对T型连接初始刚度、极限破坏载荷以及极限承载弯矩的影响规律。试验结果表明:构型A存在明显的初始破坏,但极限破坏载荷大于构型B;极限承载弯矩基本不随跨距改变,可作为不同跨距、不同构型T型连接优劣衡量标准。最后,基于试验结果、载荷等效与缩比原则,提出了T型连接承载特性评价方法。     

The Enfield Lock Barrel Mill of 1815 and Moves to Replace Musket Barrel Grinding by Turning c1780 to c1840

In 1841 Henry Wilkinson in his book Engines of War and William Greener in The Science of Gunnery describe a range of methods then in use for shaping the outside of gun barrels after the barrel forging process, ranging from manual off-hand grinding to the use of precision machines. In the same year G. & J. Rennie published the design of their state-of-the-art lathe that was capable of turning complex and dished barrel forms. This built upon the earlier work of both Henry Nock and John Jones. In the early years of the 19th century both Britain, at Enfield and other locations, and the USA, at Harpers Ferry and Springfield, began to introduce barrel-turning technology. This paper uses measurements taken from a significant number of military barrels made by several makers, and also newly exposed information about Henry Nock and the Enfield Factory of 1815, to understand better the technologies that were applied to military flintlock barrel finishing from the 1780s to the 1840s, and particularly during the major wars of 1793–1815, when high output was paramount. Measurements both of barrel form and out-of-roundness are presented. These allow the interpretation of the techniques being used by different makers at different locations, and raise questions about the purpose and achievement of the complex dished barrel forms found on British military flintlock muskets. This approach also allows us to better describe the earliest factory on the Enfield site, one of the most significant sites in the wider history of UK manufacturing.     

Does Military Spending Nonlinearly Affect Economic Growth in South Africa?

Using annual data collected from 1988 to 2015, this study provides evidence of a non-linear relationship between military spending, economic growth and other growth determinants for the South African economy. The empirical study is based on estimates of a logistic smooth transition regression (LSTR) model and our empirical results point to an inverted U-shaped relationship between military spending and economic growth for the data. Furthermore, our empirical results suggest that the current levels of military spending, as a component of total government expenditure, are too high in the South African economy and need to be transferred towards more productive non-military expenditure in order to improve the performance of economic growth and other growth determinants.     

中低速磁浮列车传感器防浪涌设计及改进

为提高磁浮列车悬浮传感器的可靠性,分析在雷击、电源干扰等工况条件下的浪涌产生机理,确定浪涌冲击试验的内容,从通流量的角度说明已有防浪涌电路设计的可行性,并指出其在高温环境下在可靠性方面存在的不足。分别从降压和分流的角度进行分析,通过在原有电路中并接大容量电容的方式降低浪涌对敏感器件的冲击,从而提高传感器电源的抗浪涌冲击能力。     

石墨烯微片尺寸对石墨烯纸热导率的影响

石墨烯热导率远高于传统金属薄膜等导热材料,可用作热扩散材料。石墨烯纸由石墨烯微片组装而成,石墨烯微片尺寸大小对其组装方式微观结构以及宏观导热性能等具有重要影响。采用溶液过滤自组装方法制备了分散均匀的氧化石墨烯纸,然后在Ar/H2气氛下对氧化石墨烯纸进行热还原处理,得到了石墨烯纸。结果表明,大尺寸石墨烯微片组成的石墨烯纸结构更加致密、结晶度更高;0.5μm~3μm和50μm~100μm的氧化石墨烯所制备的石墨烯纸的热导率分别为632.8 W/m K和683.7 W/m K,大尺寸石墨烯微片组成的石墨烯纸热导率提高了8%。     

敷设气囊的充水圆柱壳的声辐射

为降低充水圆柱壳受内部点声源激励时的水下辐射噪声,在其外壳上敷设气囊,形成气囊圆柱壳。为指导气囊圆柱壳的设计,将充水裸圆柱壳和充水气囊圆柱壳分别简化为单、双层无限长隔板。比较隔板、气体与水的波阻抗,分析了气体声速与层厚对双层无限长隔板在平面声波入射时低频声辐射的影响机理。分析表明,声速小的气体和适当的气层厚度可以降低双层障板的辐射噪声。采用声无限元法计算了气囊圆柱壳的水下声辐射,结论与对隔板的机理分析吻合。优化设计出的充水CO2气囊圆柱壳的水下辐射声功率与远场辐射声压明显低于充水裸圆柱壳。     

基于共进化的多任务分配与调度

在考虑多种约束关系基础上 ,提出一种并行与分布式系统中多约束关系的任务分配与调度的共同进化遗传算法。仿真试验结果表明所给算法比传统单种遗传算法更能有效地进行多任务分配与调度 ,具有一定的工程价值     

南疆阿拉尔垦区九团流动人口基本势态分析

由于自然资源禀赋差异的存在,部分省份的流动人口在利益的驱使下移入南疆垦区.他们是本地三产的主力,对边疆的稳定和发展做出了贡献.本文采用了实证的方法研究了这些人员的基本结构、流动原因、流动率及其社会形态,使他们的生存环境得到改善,安心屯垦戍边.