胶带输送机运输事故树可靠性的计算机模拟

以胶带输送机运输事故树的计算机模拟过程为例 ,介绍了对事故树可靠性进行计算机模拟的原理、算法以及程序运行步骤 ,编制了模拟程序。用笔者提出的理论、方法及模拟程序 ,对平顶山煤业集团一矿胶带输送机运输事故进行了事故树分析与求解 ,同时将模拟程序运行结果与最小割集法求得的理论值进行了对比 ,计算结果误差小 ,所得结论准确可靠 ,为类似事故的模拟分析提供了一种新的方法和途径     

A GIS/Simulation Framework for Assessing Change in Water Yield over Large Spatial Scales

Recent legislation to initiate vegetation management in the Central Sierra hydrologic region of California includes a focus on corresponding changes in water yield. This served as the impetus for developing a combined geographic information system (GIS) and simulation assessment framework. Using the existing vegetation density condition, together with proposed rules for thinning to reduce fire risk, a set of simulation model inputs were generated for examining the impact of the thinning scenario on water yield. The approach allows results to be expressed as the mean and standard deviation of change in water yield for each 1-km² map cell that is thinned. Values for groups of cells are aggregated for typical watershed units using area-weighted averaging. Wet, dry, and average precipitation years were simulated over a large region. Where snow plays an important role in hydrologic processes, the simulated change in water yield was less than 0.5% of expected annual runoff for a typical watershed. Such small changes would be undetectable in the field using conventional stream flow analysis. These results suggest that use of water yield increases to help justify forest-thinning activities or offset their cost will be difficult.     

流域地理景观生成中纹理映射技术

洪水演进仿真系统的研制是进行“数字流域”工程建设的重要研究内容,系统的研制必须利用先进的模拟仿真与可视化方法等现代计算机技术,在计算机生成的虚拟环境中,对洪水在现实河道里的推进情况以及洪水对流域内区域的淹没情况进行仿真模拟。系统的可视化以流域地形的仿真为基础,流域三维景观的生成则是洪水演进仿真系统的主要可视化需求,纹理映射技术是实现流域三维景观的重要技术手段。在分析比较计算机图形学中的几种典型纹理映射方法基础上,针对复杂流域地形貌和卫星遥感流域数据源特点,研究了相应的纹理映射算法模型。使用Visual C 系统开发语言,依据清江流域的真实数据源生成清江流域三维网格地形,并基于OpenGl技术,运用逆透视过程和非参数映射方法,实现了清江流域三维景观的真实纹理粘贴,使生成的流域景观具有真实自然的三维可视化效果。     

Simulation of Live and Dead Phytomass Formation and Transformation in Optimized Agrocenoses

The formation and transformation of live and dead phytomass in agrocenoses with a complex horizontal structure are described. These processes are demonstrated to be specific and to be determined by differences in the horizontal structure. Only agrocenoses of a mosaic structure (with square parcels) have optimal conditions for these processes.     

Compostability of Poly(lactide): Degradation in an Inert Solid Medium

Commercial poly(lactide) degradation was studied in an inert solid medium simulating compost conditions, with the aim to achieve a complete carbon balance of the polymer degradation. The mineralisation rate at the end of the test was compared to those obtained for poly(lactide) degradation in compost. It was shown that the mineralisation rate after 45 days of degradation was quite lower in inert solid medium than in compost but the standard deviation of data was enhanced. A protocol for both extraction and quantification of the carbon included in the different degradation by-products was proposed and the carbon balance of the polymer degradation was followed during the test with a satisfactory accuracy. The non-degraded PLA material was recovered during the test, hence the evolution of the glass transition temperature and the molecular weight was followed. A two-step degradation mechanism was highlighted in inert solid medium, showing the fundamental role of abiotic reactions for PLA degradation in compost.     

呼和浩特强对流天气的数值模拟分析

利用三维积云数值模式模拟了呼和浩特地区强对流天气的发展过程，并结合实时雷达回波资料进行了对比分析，指出模式输出的部分物理量与理论值、雷达回波或地面天气及降雹（水）实况符合得较好。从对模式输出的几个物理量的统计分析，得出利用三维积云数值模式预测强冰雹过程的概念模型。结果表明，三维积云数值模式能用于模拟对流云特别是强对流云的发展过程，可在人工影响天气业务工作中应用并不断发展。     

某厂化学装置爆炸对设备房结构的损坏——调查与模拟分析

在对某厂化学爆炸所作的现场调查的基础上，对设备房钢筋混凝土框架结构构件的受损状况进行了分类描述，采用有限元方法对框架结构在静力和爆炸冲击荷载下的反应进行了模拟分析，分析结果与现场调查情况基本一致，给出了一些有意义的结论。     

火灾模拟结果误差分析的函数分析法

火灾试验结果和模拟预测结果常能表达成关于时间变化的曲线,为定量描述两种随时间变化曲线间相符合的程度,引入误差分析的函数分析法。采用适合于低Mach数流修正的N-S方程描述烟气的输运过程,使用大涡模拟和Smagorinsky亚格子模型,对封闭空间内的火灾过程进行数值模拟;对其计算结果的分析表明,函数分析法能定量对模拟预测曲线与试验曲线间的差别进行描述,模是两曲线值大小的相对误差的度量,余弦是两曲线形状相似程度的度量。     

交通事故再现技术研究现状与发展趋势

道路交通事故再现不仅是交通事故责任鉴定和原因分析的重要方法,也是交通事故防治的重要内容。在详细介绍国内外事故再现计算机仿真技术的基础上,分析目前事故再现系统开发中事故现场数据采集技术、碰撞前后速度估算的技术、碰撞过程进行模拟的虚拟现实技术的研究现状与存在的问题,提出进一步优化的方向,进而达到完善交通事故模拟再现的目的。最后指出我国交通事故再现技术进一步研究的内容和发展趋势。     

化学事故救援方舱舱室环境安全性模拟研究

运用计算流体动力学(CFD)方法,对具有超压防护功能的某化学事故应急救援手术方舱室内气体污染物运动扩散的规律以及对人员安全的影响进行了数值模拟,其研究结果表明:当大气环境中氢氰酸(HCN)浓度为5mg/L时,前10s从常规进风口进入舱室的HCN在滤毒通风装置开启后,随气流运动逐渐向整个舱室扩散,经净化空气的混合稀释作用,绝大部分通过舱体缝隙排出舱室,30min内舱室HCN浓度的总量下降了95.1%,说明超压防护很好地保证了舱室环境的安全性。