一种强安全约束机制下的云计算任务调度方案

针对云计算技术中的资源调度时间长、开销大、不考虑调度安全的问题,本文在对常见的云环境下工作流任务的资源调度问题进行建模的基础上,提出了一种强安全约束机制下的云计算任务调度方案。该方案按照所用方法的安全强度,再加上相关软件的安全程度,赋予虚拟机不同的安全等级;另一方面,其按照用户的需求等诸多方面,能够赋予操作不同的安全需求等级;最后使用变近邻粒子群算法对该问题进行了求解。在CloudSim仿真平台上的实验结果证明,本文提出的算法与用最大－最小蚁群算法、遗传算法与该算法相比,该算法具有很好的可用性和寻优能力。     

Verification of thermal restraint of a railways trough structure by long-term monitoring

At the central railway station of Berlin a trough structure was erected to extend the tracks from the underground station to ground level. The trough is subjected to high ground water pressure. Safety against up-lift called for the coupling of the trough with the underwater concrete slab and the back-anchorage of the structure by piles. Such coupling leads to high restraint due to hydration of the concrete and the ambient weather. Analysis required assumptions regarding the interaction between the trough and the impeding sub-structure, as well as the stipulation of load-independent design actions based on meteorological studies. The owner decided to install a long-term monitoring system in order to verify the thermal and mechanical response of the structure. However, the main goal of monitoring is the improvement of specifications for design and tender of future structures with comparable complexity. The program and the monitoring techniques will be described, and specific results will be reported. Preliminary conclusions are drawn.     

自由曲面数控加工刀具轨迹生成的约束条件分析

在提出自由曲面数控加工过程和刀具轨迹的规划原则情况下,分析无干涉控制、恒表面速度进给、伺服能力控制和相邻加工曲线影响等轨迹控制的约束条件,实时对轨迹的生成进行系统优化控制。通过系统分析刀具轨迹生成的约束条件,为刀具轨迹优化控制提供决策,对提高自由曲面的切削质量和加工效率具有重要意义。     

带阻尼梳形张力装置的运动分析

本文系统地分析了有阻尼梳形张力装置的运动。提出了确定有阻尼时的梳形张力装置极限频率的方法，测试张力装置的阻尼系数、固有频率的方法，以及确定普通卷纬机张力装置极限锭速和弹簧弹性系数的方法。     

机构的运动分析

本文借助于齐次变换，分析了局部坐标系之间的相对运动关系，论述了相对运动约束矩阵的拓扑关系，提出了机构运动的模拟方法。     

Prediction of restrained shrinkage based on restraint factors in patching repair mortar

Shrinkage of repair material, especially in patching repairs, is the major factor inducing cracking in concrete repairs. Induced cracks in repair materials are due to restrained shrinkage. Although in usual practice, the free shrinkage of the repair mortar is measured, in reality, cracking is not due to free shrinkage. It is well known that cracking is due to restrained shrinkage. It is very hard to measure the restrained shrinkage; therefore, to overcome this problem a restraint factor (R) is used to modify the free shrinkage and come up with the restrained shrinkage. The restraint factor is influenced by the surface and boundary condition.In this study, the restraint factor for patching repair with different boundary conditions (with eaves and without eaves) and surface condition (rough and smooth) of the substrate concrete is investigated.The results show that the restraint factor R lies between 0.1 and 0.94; with an increase of restraint, the restraint factor is increased. In situations with a high level of restraint (eaves at the perimeter and a rough surface of substrate), the average R is 0.83. while with a low level of restraint (without eaves at the perimeter and a smooth surface of the substrate), the average R is 0.22.     

法律规范对塑料在包装领域发展的作用

介绍了塑料包装材料的发展现状;讨论了法律法规对塑料在包装领域的健康有序发展的重要作用;并提出法律法规应从安全性、环保性、节能性等方面对塑料包装材料进行规范的建议。总结出新型高性能、环境友好、节能型塑料包装材料是今后研究发展的主要趋势。     

绞车行星传动机构自适应问题研究

绞车是矿山中量大面广的设备，绞车中普遍使用行星齿轮传动机构，这种机构具有结构紧凑、重量轻、体积小、传动比大和承载；能力强、传动功率高等优点。     

不同掺合料对碱-硅反应的抑制及比较研究

在掺合料对碱-硅反应的抑制机理基础上,根据不同矿物掺合料对碱-硅反应的抑制试验结果,比较并分析了四种掺合料对碱-硅反应的抑制效果.结果表明,硅粉对混凝土碱一硅反应的抑制效果最好,当硅粉掺量为15%时,抑制率可超过90%;粉煤灰和石灰石粉的抑制效果次之,而矿渣的抑制效果相对较差.     

自定心钻床的研制

在介绍自定心钻床设计原理的基础上,对钻床的对心效应和受迫振动进行了研究,并建立了简化的振动模型,提出了抑制振动的方法.自定心钻床,可部分地代替大型数控铣在大型天线零件上钻高精度小孔.