故障树分析法及其在导弹故障近似计算中的应用

介绍了故障树分析法的主要分析过程,指出故障树分析法是进行产品设计和系统故障诊断的有效方法,并利用Visual C 语言进行蒙特卡罗仿真,得到了近似计算故障树顶事件发生概率时应选取的最优权因子,最后指出该因子可以用在导弹等特殊设备故障的近似计算中。     

Regeneration of Nothofagus pumilio [Poepp. et Endl.] Krasser forests after five years of seed tree cutting

Nothofagus pumilio [Poepp. et Endl.] Krasser is a deciduous tree species that grows in Chile and adjacent Argentina between 36 and 56 degrees S, often forming the Andean tree line. Silvicultural systems proposed for this species integrate both regeneration and intermediate level operations in an orderly process for managing forest stands. The seed-tree method of regeneration has been used to manage even-aged stands of this species. This paper investigates the effect of seed tree cuttings on the regeneration of Nothofagus pumilio [Poepp. et Endl.] Krasser forest located in the Magallanes region (Chile). The studied forest was managed on an even-aged basis using a seed tree silvicultural system for regeneration with an intensity of cutting of 65-70% of the basal area and a minimum of 15 dominant lenga trees per hectare retained. A regeneration inventory sampling was used to quantify regeneration attributes in the study area. Regeneration was found to be significantly affected by the seed tree cuttings. In fact, the number of established individuals rose from 0.39 to 26.7 plants m(-2) pre-harvest to 9.2-21.5 plants m(-2) post-harvest, depending on the particular development stage. Total regeneration ranged from 9.5 to 48.2 plants m(-2). The number of plants established over the period 1992-1997 was related to the residual basal area, coverage and number of trees. However, mean tree height was not significantly related to any regeneration variable. Significant variables were used to establish a regeneration prediction model using single and multiple linear equations (R2<0.418). Consequently, the seed tree method of regeneration can be considered feasible for commercially valuable lenga forests, although this method, in its strictest application, will create many large, irregularly shaped, even-aged groups.     

SO2气体对树木叶片叶绿素含量的影响

应用分光光度法研究乌鲁木齐市常见行道树种新疆扬、大叶白腊和新疆大叶榆受ＳＯ２气体危害后,树木叶片叶绿素（ＣＡ、ＣＢ、Ｃｒ）含量的动态变化,以了解其抗性特点。表明,名树种在受危害全进程中其表现不同,树木一身亦具有一定的自调节能力。同时叶绿素在各阶段相对含量的动态变化特点是衡量树种抗性大小的可供参考的有价值指标之一。     

LPG储罐的失效原因分析

简要介绍了LPG储罐的各种失效形式及其特征,分析了导致储罐失效的主要原因,用事故树分析方法进行整理归纳,并针对各种失效形式分别提出防治措施.     

判别分析与决策树分析在化学物质生态危害分类中的应用

运用Fisher判别、马氏距离判别和决策树分析3种方法对61种环境优先污染物的生态危害程度进行分类,并比较了各模型的分类正确率.结果显示,决策树分析方法分类正确率最高,为92%;马氏距离判别其次,为87%;Fisher判别最低,为75%.决策树分析方法不仅减少了2项评价指标,而且对61个新数据矩阵的多次分析显示其分类能力非常稳定,正确率基本符合正态分布,且保持在92%左右,为3种方法中最优的分类方法.     

一起带状屑割伤车工双腿事故的原因及预防措施

利用安全系统工程学中事故树分析法对带状屑割伤车工双腿事故进行了分析 ,并提出了防止事故发生的预防措施。     

When Ecosystem Services Crash: Preparing for Big,Fast, Patchy Climate Change

Assessments of adaptation options generally focus on incremental, homogeneous ecosystem responses to climate even though climate change impacts can be big, fast, and patchy across a region. Regional drought-induced tree die-off in semiarid woodlands highlights how an ecosystem crash fundamentally alters most ecosystem services and poses management challenges. Building on previous research showing how choice of location is linked to adaptive capacity and vulnerability, we developed a framework showing how the options for retaining desired ecosystem services in the face of sudden crashes depend on how portable the service is and whether the stakeholder is flexible with regard to the location where they receive their services. Stakeholders using portable services, or stakeholders who can move to other locations to obtain services, may be more resilient to ecosystem crashes. Our framework suggests that entering into cooperative networks with regionally distributed stakeholders is key to building resilience to big, fast, patchy crashes.     

用于早期火灾分类的非线性决策树支持向量机

对早期火灾信息进行研究,提出了一种基于非线性决策树的支持向量机多类分类模型。该模型利用非线性映射将样本投影到高维特征空间,比较每类样本在高维空间的分布情况,进行聚类构造出一个二叉决策树,使容易区分的类别从根节点逐层分类出来,有效克服了错分积累和避免不可分情况;同时,各个节点采用二值最小二乘小波支持向量机,以获得较高的泛化能力。该文将该模型用于早期火灾分类,并与BP神经网络、K近邻法和决策树方法进行比较,实验结果表明,该模型对早期火灾的识别率更高。     

基于事故树理论的非金属矿山爆破事故致因分析

采用安全系统工程方法,以陕西省某大理石矿为例,对非金属矿山爆破事故进行了事故树分析,并绘制出爆破事故树分析图,直观地表现了各可能导致顶上事件发生的基本事件及其逻辑关系,通过对FTA的定性分析,得出了最小割集和结构重要度,并提出了相应的安全对策.     

The discovery of ash dieback in the UK: the making of a focusing event

Why did the identification of ash dieback (Chalara Fraxinea) in 2012 in the UK catch the national media, public, and political zeitgeist, and lead to policy changes, in a way that no other contemporary tree pest or pathogen outbreak has? The identification of ash dieback in the UK is conceptualised as a successful ‘focusing event’, and the ways in which it was socially constructed by the media, stakeholders, and the government are analysed. National newspaper coverage contributed to the way that the disease was understood and was significant in driving the political response. Ash dieback’s focal power derived from the perceived scale and nature of its impact, the initial attribution of blame on government, the war-like response from the government, and Ash’s status as a threatened native tree. The ash dieback focusing event has increased the salience of plant health issues amongst policymakers, the public, and conservation organisations in the UK.