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1.
为充分利用油气管道历史失效数据,减少失效概率评估过程中的主观性,提出油气管道基本失效概率的概念及评估方法。对美国管道及危险物品安全管理局数据库的油气管道里程数据、事故数据及失效因素数据进行全面分析,采用基于事故统计的方法评估油气管道基本失效概率。结果表明:美国危险液体管道、输气集气管道、配气管道发生一般事故的基本失效概率分别为1.29次/(10^3 km·a)、2.17次/(10^4 km·a)及4.08次/(10^5 km·a),发生较大事故的基本失效概率分别为4.58次/(10^4 km·a)、1.41次/(10^4 km·a)及2.38次/(10^5 km·a),发生重大事故的基本失效概率分别为9.09次/(10^6 km·a)、9.79次/(10^6 km·a)及1.11次/(10^5 km·a)。美国基本失效概率可作为油气管道失效概率评估的基准线,也可作为风险可接受标准的依据,但不能直接应用于中国管道风险评价,需对其进行修正,建立适用于中国管道的失效数据库。 相似文献
2.
Bijan Payandeh 《New Forests》1988,2(3):145-160
Drainage and fertilization of an existing peatland black spruce (Picea mariana (Mill.) B.S.P.) stand and 24 possible methods of planting a clear-cut area near Cochrane, Ontario were evaluated by means of a recently developed forestry investment decision model, FIDME.Results indicate that, on the basis of the cost estimates used and assumptions made, drainage of the existing stand is the most economical treatment if it can reduce the rotation age by 30 years or more. Drainage combined with fertilization is the second best alternative if this treatment can reduce the rotation age by 40 years or more. Fertilization of the undrained site ranks a distant third, and then only if it reduces the rotation age by 10 years; otherwise, it will be uneconomical to apply.In the case of the clear-cut area, planting bare-root stock on a mechanically prepared but undrained site without weed control ranked first among the 24 alternatives considered; the same treatment, but with weed control included, ranked second. Planting containerized seedlings on a mechanically prepared but undrained site with weed control ranked third, followed by planting bare-root stock on a mechanically prepared and drained site with weed control. In contrast, planting containerized seedlings on an unprepared site and with no weed control ranked as the least cost-effective method considered. 相似文献
3.
以黄河兰州段11个不同采样点3种多环芳烃的临测浓度及其对6~38种水生生物的LC50为基础资料,分别应用商值法、概率密度函数重叠面积和联合概率曲线3种风险浮价方法对黄河兰州段苯并(a)芘、荧蒽、芘的生态风险进行了评价.结果表明:黄河兰州段3种PAHs残留具有一定的生态风险.其中低暴露风险条件下(受威胁生物不超过1%),... 相似文献
4.
Rodney L. Robichaud Jeffrey C. Glaubitz Olin E. Rhodes Jr. Keith Woeste 《New Forests》2006,32(2):179-196
We describe the development of a robust and powerful suite of 12 microsatellite marker loci for use in genetic investigations
of black walnut and related species. These 12 loci were chosen from a set of 17 candidate loci used to genotype 222 trees
sampled from a 38-year-old black walnut progeny test. The 222 genotypes represent a sampling from the broad geographic distribution
of the species. Analysis of the samples using the 12 loci revealed an average expected heterozygosity of 0.83, a combined
probability of identity of 3×10−19, and a combined probability of exclusion for paternity analysis of >0.999. The 222 genotyped trees from the progeny test
comprised 39 open-pollinated families, 29 of which (having at least five sampled progeny) were used to estimate the outcrossing
rate for the progeny trial. The same 29 families were used to construct a Neighbor-Joining dendrogram based upon allele sharing
between individuals. The multilocus estimate of the outcrossing rate was 100% (standard error of zero), higher than the 90%
level found in previous studies at the embryo stage, suggesting that both artificial and natural selection against selfs may
have occurred over the 38-year lifespan of the progeny trial. In the Neighbor-Joining dendrogram, the majority of the putative
siblings grouped together in 21 out of the 29 families, showing that the microsatellites were able to discern most of the
family structure in the dataset. Our results indicate that errors were sometimes committed during the establishment of the
progeny test. This set of microsatellite loci clearly provides a powerful tool for future applications in black walnut. 相似文献
5.
《国际水土保持研究(英文)》2020,8(4):440-451
Soil erosion is one of the most severe global environmental problems, and soil erosion surveys are the scientific basis for planning soil conservation and ecological development. To improve soil erosion sampling survey methods and accurately and rapidly estimate the actual rates of soil erosion, a Pan-Third Pole region was taken as an example to study a methodology of soil erosion sampling survey based on high-spatial-resolution remote sensing images. The sampling units were designed using a stratified variable probability systematic sampling method. The spatiotemporal characteristics of soil erosion and conservation were taken into account, and finer-resolution freely available and accessible images in Google Earth were used. Through the visual interpretation of the free high-resolution remote sensing images, detailed information on land use and soil conservation measures was obtained. Then, combined with the regional soil erosion factor data products, such as rainfall-runoff erosivity factor (R), soil erodibility factor (K), and slope length and steepness factor (LS), the soil loss rates of some sampling units were calculated. The results show that, based on these high-resolution remote sensing images, the land use and soil conservation measures of the sampling units can be quickly and accurately extracted. The interpretation accuracy in 4 typical cross sections was more than 80%, and sampling accuracy, described by histogram similarity in 11 large sampling sites, show that the landuse of sampling uints can represent the structural characteristics of regional land use. Based on the interpretation of data from the sample survey and the regional soil erosion factor data products, the calculation of the soil erosion rate can be completed quickly. The calculation results can reflect the actual conditions of soil erosion better than the potential soil erosion rates calculated by using the coarse-resolution remote sensing method. 相似文献
6.
钟朝艳 《湖南农业大学学报(自然科学版)》2011,(1):85-88
考虑到保险公司在实际经营中收益所具有的不确定性和分红策略,建立一类具有线性红利界和带随机扰动的双复合Poisson风险模型,利用鞅方法给出模型关于破产概率的一个定理及上界. 相似文献
7.
盖维丹 《湖南农业大学学报(自然科学版)》2016,(2):29-33
研究了一类具有常利率及相依结构的Sparre Andersen模型, 模型中假设理赔间隔时间决定下一次理赔额的分布情况. 对一般分布情形, 利用推广后的调节系数方程与递归更新技巧, 得到了此模型的最终破产概率上界的估计. 最后以理赔额和理赔间隔时间都服从指数分布的情况下的实例分析来说明该模型的有效性. 相似文献
8.
9.
大坝安全风险评估初探 总被引:4,自引:0,他引:4
根据风险理论在其它领域的应用实践,以及大坝安全风险管理在国外的应用经验,将大坝安全风险评估的原理、实施步骤等进行了阐述,探讨了大坝风险因素、失事树分析法及事件概率计算方法等诸多关键问题,并通过算例对文中所探讨的问题进行了较为明确的应用与说明。 相似文献
10.