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61.
泥石流研究中的粒度分析方法及其应用 总被引:1,自引:0,他引:1
粒度分析是泥石流研究的一个重要手段,是它的基础实验之一。本文介绍了在泥石流研究中一些较常用的及有应用前景的粒度分析方法,它们包括:频率累积曲线、直方图、概率累积曲线、粒度参数统计、粒度参数散点图等;对粒度分析在泥石流的分类、物理参数的计算、水力学条件的分析等方面的作用也做了一些初步的探讨。 相似文献
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将运筹学中“部分排序”的概念引入对污染物的环境影响比较评价中,以环境中常见的10种残留农药为应用实例,用Hasse图表示出比较评价的结果。和普遍排序技术相比,部分排序的评价结果简明直观、合理、可靠。Hasse图技术充分考虑了所要评价的各方面因素,避免了在普遍排序过程中由于确定评价模型中的权值而带来的主观因素的影响。 相似文献
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Joseph Alcamo Lilibeth Acosta-Michlik Alexander Carius Frank Eierdanz Richard Klein Dörthe Krömker Dennis Tänzler 《Regional Environmental Change》2008,8(4):137-149
In this study we develop an “inference modeling” approach to compare and analyze how different disciplines (economics, political
science, and behavioral science/environmental psychology) estimate vulnerability to drought. It is thought that a better understanding
of these differences can lead to a synthesis of insights from the different disciplines and eventually to more comprehensive
assessments of vulnerability. The new methodology consists of (1) developing inference models whose variables and assertions
incorporate qualitative knowledge about vulnerability, (2) converting qualitative model variables into quantitative indicators
by using fuzzy set theory, (3) collecting data on the values of the indicators from case study regions, (4) inputting the
regional data to the models and computing quantitative values for susceptibility. The methodology was applied to three case
study regions (in India, Portugal and Russia) having a range of socio-economic and water stress conditions. In some cases
the estimates of susceptibility were surprisingly similar, in others not, depending on the factors included in the disciplinary
models and their relative weights. A new approach was also taken to testing vulnerability parameters by comparing estimated
water stress against a data set of drought occurrences based on media analysis. The new methodologies developed in this paper
provide a consistent basis for comparing differences between disciplinary perspectives, and for identifying the importance
of the differences.
相似文献
Joseph AlcamoEmail: |
66.
用剪力图面积法绘制弯矩图 总被引:1,自引:0,他引:1
在建筑力学中,弯矩图的绘制是结构设计的基础和依据.通过对梁上外荷载与内力间微积分关系及函数图形的研究,找到了剪力图与弯矩图的内在规律,得到一种绘制弯矩图的新方法——剪力图面积法,应用这种方法可大大提高作图速度和效率.图1,表1,参6. 相似文献
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陈金全 ' target="_blank" rel="external"> 王继仁 ' target="_blank" rel="external"> 岳立柱 《中国安全生产科学技术》2019,15(2):89-93
为了解决采空区煤自燃可能性评价方法中的赋权争议问题,基于偏序集理论,提出了偏序集评价模型。阐明评价指标并确定其等级划分准则,运用偏序集评价模型得到Hasse图,通过Hasse图展现的层集信息判别采空区煤自燃的危险程度。利用该模型对某煤矿17个煤样的自燃情况进行了判别,评价结果准确合理。研究结果表明:该模型避免了以往研究中的赋权争议问题,克服了样本量不足致使模型无法应用的问题,其评价结果置信度高。 相似文献
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Methodologies of API 579 have been widely accepted as the de-facto standard guideline for fitness for service assessment on crack-like flaws in pressure equipment. For different purposes and needs, the evaluation is divided into three levels, from critical length estimation in level 1, use of the failure analysis diagram (FAD) in level 2, to performing finite element stress analysis in level 3, that is from simplified to accurate. It is generally considered safe as long as the crack is smaller than the critical crack, but not all of them are actually the case. Therefore, it is very important to study the physical meaning behind the critical crack and understand the conservativeness of it.In this study, numerous examples of critical cracks determined according to API 579 Level 1 were put into Level 2 analysis for comparison. Each case is mapped onto the FAD of level 2 analysis to see its position and distance from the borderline between safe and danger zones. A huge amount of examples covering the majority of possible scenarios, including the geometry, thickness, inner diameter, pressure and half-length of the flaw, depth of the crack, crack tip and crack bottom, as a whole, there are 960 cases to be analyzed.Results show that cracks on the circumferential direction of the cylindrical and spherical vessels are distributed tightly in a small area far from the borderline on the FAD diagram. In these cases, the vessel is actually not as dangerous as the critical crack implies, since most of the points lie quite far from the danger zone. As for the longitudinal cracks of a cylindrical vessel, the results are scattered around, and three data points are located outside the allowable zone. The peculiar results are partly due to a discrepancy of interpolating procedure as the influence coefficient is being computed. Through this study, it is also found that the cumbersome process of estimating the critical crack length can be greatly simplified for longitudinal cracks in a cylindrical vessel. 相似文献