GO法进行有共因失效系统可靠性分析的新算法研究

共因失效可能使系统的可靠性大大降低,是系统可靠性分析中的重点和难点。GO法可以对含共因失效的系统进行可靠性分析。为了选取已有算法合适的参数,更为了提高有多个共因失效组系统的GO法可靠性分析效率,进行了相关研究。对关键参数公式进行了理论分析,并就几个算例系统进行了计算试验;对已有算法进行了深入研究,为了改进已有算法对共因失效组逐个处理,提出了将共因失效组中的部件均由本组等效共因失效部件代替的新算法。进而,应用分组法和新算法对一个简单示例系统和外电源备用系统进行了共因失效分析。给出了对已有算法参数选取的建议;通过对比可知分组法与新算法计算结果相近。通过对已有算法参数的合理化选取,可以提高计算结果的准确度;新算法可对所有共因失效组一次性处理,是共因失效分析的有效方法。     

Community‐based water supplies in Cikarang,Indonesia: are they sustainable?

Community‐based water supply (CBWS) is an example of how a community manages common pool resources (CPR). This results in an alternative approach to solve water supply problems in developing countries by enhancing community participation in managing water supply. This research evaluates the sustainability of five CBWS projects in Cikarang, Indonesia by using Ostrom's design principles, with additional sustainability factors found in the Sustainable Development Goal (SDG) on drinking water and groundwater sustainability. Quinn et al. (2007) criteria were used in the analysis, and the results show that the management of four CBWS institutions were absent and one CBWS institution was weak. With regards to the SDG's drinking water target, the CBWS institutions were unable to comply with safe water standards, and in terms of groundwater sustainability, efforts to monitor and sustain groundwater tables were absent. Results from this research suggest that more focus must be placed on water quality and groundwater sustainability for CBWS projects.     

Government management and overexploitation of groundwater resources: absence of local community initiatives in Ardabil plain-Iran

Although mismanagement of groundwater resources has resulted in their destruction over centuries, climate change is speeding up this process more than ever. On the one hand, urgent action by government bodies is needed to address the challenge. On the other hand, a vast body of literature proves that bottom-up collective action, although requiring a longer time period, is a better solution to manage such resources. This research aims to address this dilemma. The groundwater resource in Ardabil plain in Iran, which has long been managed solely through government intervention, has been chosen as a case study to explore the opportunities and limitations of managing a critically endangered area from a common pool resource perspective. Our study suggests that managing Ardabil groundwater resources should be conducted on two scales. The bottom-up institutional agreements should take place at village scale while the government should stay in charge of the overall organization at plain scale.     

Individualized water source as an indicator of attitudes about water management and conservation in humid regions

Public perceptions about water quantity and water as a common pool resource are understudied in humid regions. As water demand increases, the need to more closely manage water, even in humid areas, will increase, requiring better understanding how people perceive their water supply, how they view paying for water conservation and how water user characteristics influence attitudes. A survey finds correlations between utilizing an individual water source (e.g. well or spring) and attitudes toward water management and conservation. Compared to respondents with a shared water source, those with an individual source believe they are segregated from regional water concerns. They are less willing to pay for water management or conservation measures and less supportive of any government intervention in water management. These results suggest that planners and water managers may face resistance to conservation policies or any policy based on the idea of water as a common pool resource.     

The role of time and species identities in spatial patterns of species richness and conservation

Many conservation actions are justified on the basis of managing biodiversity. Biodiversity, in terms of species richness, is largely the product of rare species. This is problematic because the intensity of sampling needed to characterize communities and patterns of rarity or to justify the use of surrogates has biased sampling in favor of space over time. However, environmental fluctuations interacting with community dynamics lead to temporal variations in where and when species occur, potentially affecting conservation planning by generating uncertainty about results of species distribution modeling (including range determinations), selection of surrogates for biodiversity, and the proportion of biodiversity composed of rare species. To have confidence in the evidence base for conservation actions, one must consider whether temporal replication is necessary to produce broad inferences. Using approximately 20 years of macrofaunal data from tidal flats in 2 harbors, we explored variation in the identity of rare, common, restricted range, and widespread species over time and space. Over time, rare taxa were more likely to increase in abundance or occurrence than to remain rare or disappear and to exhibit temporal patterns in their occurrence. Space–time congruency in ranges (i.e., spatially widespread taxa were also temporally widespread) was observed only where samples were collected across an environmental gradient. Fifteen percent of the taxa in both harbors changed over time from having spatially restricted ranges to having widespread ranges. Our findings suggest that rare species can provide stability against environmental change, because the majority of species were not random transients, but that selection of biodiversity surrogates requires temporal validation. Rarity needs to be considered both spatially and temporally, as species that occur randomly over time are likely to play a different role in ecosystem functioning than those exhibiting temporal structure (e.g., seasonality). Moreover, temporal structure offers the opportunity to place management and conservation activities within windows of maximum opportunity.     

浅析环境权的法理基础

环境权正在从应有权利走向实在权利，本文分析了环境权的法理基础存在的原因，指出环境权法理基础就是生存、自由、平等、可持续发展、共存。     

农地整理的委托代理关系研究

农地整理有利于提高农业生产率,是优化配置土地资源的重要手段,但我国的农地整理效率亟待提高。在农地整理项目实施中,村组干部是地方政府与农民的共同代理人。本文运用共同代理模型从理论上进行推演,认为在委托人利益目标一致的前提下,委托代理双方利益达到次优均衡;而当委托人利益目标发生背离时,共同代理人的行为出现偏差,农地整理项目的效率降低。并通过多元定序变量回归分析,基于湖北省调查数据证明该理论推导。研究结果显示,影响农民评价农地整理工程质量的主要因素是农民身份、项目的规划设计与施工质量、农民的农地整理参与程度及对地方政府的信任程度。研究结果说明,地方政府与农民在农地整理中的利益目标不一致,属于异质的委托人,且两者地位悬殊,地方政府属于强势委托人,而农民则是弱势委托人。作为共同代理人的村组干部在利益抉择中会选择与强势的地方政府合作,并进行利益合谋,最终导致农地整理工程质量低下。研究结论如下:1打破现有农地整理中的共同代理关系,促使地方政府转变职能,强化其代理服务意识,与农民组成利益一致的同质委托人,避免共同代理人与强势委托人的利益共谋,从而提高委托代理效率。2构建完善的农民参与体系,激发农民的参与热情,并将农民的有效参与作为农地整理后评价的重要指标,促进地方政府履行应有职责。3建立健全农地整理项目的社会监督制度,尤其是强化项目区农民的社会监督力量,有利于显化代理人投入和行为,减少道德风险,提高农地整理效率。     

污染源自动监测运行中常见问题探讨

以上海市嘉定区污染源在线监测为例,对污染源自动监测运行中常见的仪器运行稳定性差,监测数据准确度低,故障修复不及时等问题进行分析,从管理、技术、沟通三个方面提出对策和建议。     

荞麦不同器官总黄酮含量的日变化研究

研究荞麦初花期不同器官总黄酮含量的日变化趋势、最佳取样时间和取样部位,为养麦的综合开发利用提供理论依据.对4份来自不同地区的甜荞和苦养不同器官的总黄酮含量进行了日变化研究.结果表明,一天中同一品种不同器官中的黄酮含量均表现为花>叶>茎>根,且花和叶中的含量显著大于茎和根,不同品种各器官中总黄酮含量的日变化差异较大.     

一种考虑环境因素的自动步枪可靠性分析方法

目的 分析环境因素对于自动步枪系统可靠性的影响。方法 首先介绍贝叶斯网络理论,然后将自动步枪系统可靠性建模划分为刚性抛壳机构和弹匣供弹机构两大模块。在此基础上,从设计制造、使用因素和环境因素3个方面进行故障树建模。将故障树转化为贝叶斯模型后,基于给出的底事件失效概率和引入的环境影响因子,计算考虑环境因素带来的共因失效效应时自动步枪系统的可靠度。结果 从系统层面来看,环境因素的影响会使系统的可靠度下降8.1%。结论 在进行自动步枪的系统可靠性分析时,考虑由环境因素带来的共因失效效应更为符合实际情况,不考虑共因失效效应时,往往会高估子系统的可靠度。