Probabilistic loss assessment of light-frame wood construction subjected to combined seismic and snow loads

In some areas, e.g., mountainous areas in the western United States, both seismic and snow loads are significant. Limited research has been conducted to investigate the seismic risk of light-frame wood construction in those areas considering the combined loads, particularly the snow accumulation. An object-oriented framework of the risk assessment for light-frame wood construction subjected to combined seismic and snow hazards is proposed in this paper. A typical one-story light-frame wood residential building is selected to demonstrate the proposed framework. Economic losses of the building due to the combined hazards are evaluated using the proposed framework. It is found that in areas with significant snow accumulation, the snow load has significant effects on the seismic risk assessment for light-frame wood construction.     

曲边界上任意分布荷载的数值计算

1前言岩土工程数值模拟计算经常会遇到曲边界上任意分布荷载的计算问题,现行的前处理常规计算方法是假定其局部线性分布,这不仅影响计算精度,也增加了输入的工作量,因此合理处理曲边界上任意分布荷载的数值计算问题是此类软件开发的前提和基础。本文提出用二次插值函数法计算曲     

辐射、对流和导热的联合模拟方法在建筑中庭空调系统设计中的应用

对于具有大面积玻璃围护结构的建筑中庭，由于太阳辐射强、室内空间大等问题，导致热环境的控制非常复杂。对于这类建筑的空调系统设计，计算流体力学（CFD）等数值模拟方法的应用有着广阔的发展前景，但已有的数值计算方法复杂，通用性差，仅能被少数计算流体力学领域专业研究人员所掌握，这一因素大大制约了数值模拟方法的在实际工程中的广泛应用。本文对相关数值模拟方法进行了分析和总结，建立了一套简单快速的并具有合理准确性的通用联合模拟方法，并开发出相应的联合模拟计算程序。通过将模拟计算结果与实验结果进行比较，该方法的准确性得到了验证，同时将该方法应用于中庭空调系统的优化设计，表明了其在实际工程应用中的可行性。     

数据机房热环境影响因素研究

对某数据机房进行测量,以实测数据作为模拟的边界条件,采用开箱模型对机房热环境进行数值模拟,将模拟值与实测值进行对比,验证了模型的可靠性。在此基础上,分别对不同架空地板高度,送风孔板孔隙率,冷通道宽度以及不同挡板间距和高度等工况进行模拟,分析了各种因素对数据机房热环境的影响,得到了各个参数的最佳值,为数据机房的安全运行与节能优化提供指导。     

挤扩支盘桩水平荷载性能有限元分析研究

采用大型软件ANSYS,针对挤扩支盘桩的水平承载特点进行了数值模拟,构造出支盘桩和普通桩的三维模型并进行水平承载的计算比较,结果表明:支盘的设置显著地提高了桩的水平承载力,支盘的角度对桩的承载力产生较大的影响,桩的水平承载力随支盘位置的下降而降低。     

Quantifying inequality in health in the absence of a natural reference group

When quantifying inequality in health, the excess fraction (i.e. the proportional reduction in the outcome in question that would occur if all groups had the same, lowest, risk rate) is an appealing measure. If the population contains a natural, healthiest reference group, the excess fraction is straightforward to estimate. In the absence of an a priori reference group, calculating the excess fraction requires reflection, since using the group with the lowest observed risk rate as reference can lead to erroneous conclusions. This paper proposes a simple simulation procedure for calculating the excess fraction, without fixing a reference group.     

基于geo-slope软件对某边坡的稳定性分析评价

基于geo-slope分析软件,分别采用了瑞典条分法和简化Bishop法对该边坡的稳定性进行了分析,得到两种数值模拟分析的结果与初勘报告的结论一致,最后结合场地实际情况,提出了治理该边坡的有关措施和建议。     

基于Virtools的某型导弹虚拟维修视景仿真设计

使用建模工具3DSMAX2010建立了场景的三维模型和虚拟装备三维模型,运用Virtools编辑各种维修场景,构建出了与实际环境一致的虚拟维修环境。系统根据操作员的动作指令,实时显示人机交互过程,展示模型的状态变化,操作之后的场景响应过程,使得虚拟环境和实装操作一致,实现了某型导弹虚拟检测维修训练。该虚拟维修训练系统可以应用于相关部队的维修训练,达到节约训练经费,提高训练效果的目的。     

圆柱体表面缺陷检测的ANSYS仿真

采用交变磁场测量的圆柱体表面缺陷的ANSYS仿真,以各向同性铝圆柱体为试件,采用柱坐标系及矩形激励线圈,电流流向为圆柱体轴向.将圆柱体体划分后再对各分体局部网格划分.划分较密的缺陷部分向周围划分较疏部分过渡时,采用四面体自由划分衔接.对带有表面周向缺陷的圆柱体网格划分后,产生的单元类型为四面体与六面体的混合.其仿真采用波前求解器.仿真路径为激励线圈沿缺陷长度方向、经过缺陷中心点进行周向移动.     

An Improved On-line Contingency Screening for Power System Transient Stability Assessment

This paper presents a contingency screening method and a framework for its on-line implementation. The proposed method carries out contingency screening and on-line stability assessment with respect to first-swing transient stability. For that purpose, it utilizes the single machine equivalent method and aims at improving the prior developed contingency screening approaches. In order to determine vulnerability of the system with respect to a particular contingency, only one time-domain simulation needs to be performed. An early stop criteria is proposed so that in a majority of the cases the simulation can be terminated after a few hundred milliseconds of simulated system response. The method’s outcome is an assessment of the system’s stability and a classification of each considered contingency. The contingencies are categorized by exploiting parameters of an equivalent one machine infinite bus system. A novel island detection approach, appropriate for an on-line application since it utilizes efficient algorithms from graph theory and enables stability assessment of individual islands, is also introduced. The New England and New York system as well as the large-scale model of the Continental-European interconnected system are used to test the proposed method with respect to assessment accuracy and computation time.