Multiple structural modifications to dendritic ecological networks produce simple responses

Structural modifications to landscapes affect the ability of organisms to access different habitat patches. There exist, however, very few general methods by which to relate modifications to expectations of effects, and even fewer that enable understanding of how multiple modifications may interact. In the absence of any guiding principles, ecologists have assumed that interactions will result in complex landscape-scale effects. One way of understanding such effects is through rendering a landscape as a graph or network, among the simplest of which are dendritic networks typified by stream systems. Yet even for stream networks, there are no known general principles concerning the nature of interactions between multiple modifications. We developed a model to describe the ability of fish to access and use different habitat patches within dendritic networks. We used mathematical and numerical analyses of the model to investigate how the habitat value of a network is affected by changes in connectivity and habitat quality, and then to examine interactions between multiple modifications. Rather than showing complex interactions, our analytic and simulation-based results show that the combined effect of multiple modifications approximately equals the sum of individually predicted effects. Dendritic networks thus appear to respond far more simply to multiple modifications than has previously been assumed. These results have implications for stream management planning, and offer a firm foundation from which to better understand population processes within dendritic networks.     

我国煤矿安全生产事故的致灾因素分析

煤矿安全不仅关系到广大煤矿工人的生命财产安全、煤炭的安全开采,还关系到煤炭企业的和谐稳定.煤矿安全工作是党和政府管理社会、为人民服务的基本任务,是全面落实科学发展观、建设和谐社会的重要组成部分.首先对我国煤矿安全形势进行了分析,随后介绍了事故致因理论的发展,结合我国煤矿事故的特点运用现代事故致因理论对一起煤矿事故进行了分析,最后得出提高煤矿安全监管的措施.     

数量化理论Ⅲ及其在煤与瓦斯突出危险性评估中的应用

研究了数量化理论Ⅲ建立煤与瓦斯突出危险性的原理和方法,以瓦斯地质学理论为基础,建立了包括煤层瓦斯含量、煤层瓦斯压力、煤层分岔合并现象、地质构造复杂程度、煤的破坏类型等11个地质因素的煤层突出危险性评估指标体系。以数量化理论Ⅲ为工具,实例分析得出马依西一井3煤层突出危险性的敏感地质因素及因素轴F1,以该轴上得分大于0.1的地质因素作为强突出的敏感地质因素;得分小于-0.1的地质因素作为弱突出的敏感地质因素,得分在0.1--0.1之间的地质因素作为中等突出的敏感地质因素,将矿井划分为强突出、中等突出和弱突出三个区域。该方法实现了地勘阶段煤与瓦斯突出的定量分析,进一步细化了突出区域的划分。     

区域声环境质量污染水平预测方法评价与对比研究

为完成北京市“十二五”城市区域的主要声污染防治工作目标,全面提高北京市声环境质量水平,科学预测区域内在“十二五”期间噪声污染水平和发展趋势,本文以北京市某典型区域作为研究对象,在收集大量相关资料与实测历史噪声数据的基础上,运用指数平滑法与灰色模型GM（1,1）对所选定研究区域的噪声污染水平与发展趋势进行预测与分析。研究结果表明：运用指数平滑法与灰色模型对研究区域声环境噪声污染预测是可行的,北京市在“十二五”期间声环境质量水平符合《声环境质量标准》（GB3096—2008）中的一类区域标准。     

基于G1-VPRS-MIE多层次灰色理论的引水明渠运行风险评价

引水明渠的安全运行风险评价对减少和预防其在输水运行过程中的灾害发生、提高其在运营期间的社会经济效益具有重要的意义。为了对引水明渠在运行期间的风险进行合理赋权和评价,通过科学合理的方法构建了多指标参数的明渠运行风险影响因素指标体系,包括主体结构风险、自然风险、水污染风险、组织管理风险和运行调度风险5个风险因子子系统及20个二级指标在内的评价指标体系;运用G1和VPRS法分别确定各指标的主观权重和客观权重,结合MIE理论优化指标权重;根据明渠工程的运行特点,选取多层次灰色理论计算引水明渠运行风险值,并根据相关规范和安全风险评价实践确定风险评价等级。将该模型应用于引大入秦工程中,结果表明:采用序关系分析法(G1法)和变精度粗糙集理论(VPRS)并结合最小信息熵原理(MIE)的权重确定方法(G1-VPRS-MIE),不但避免了层次分析法过度依赖专家的主观经验、克服了粗糙集理论在边界刻画的局限性,而且弥补了主观和客观方法相结合的不足;对于指标权重的确定更加客观合理,既能满足所得权重的客观性,也能保证评估结果具有一定的解释性,同时能够减少单一权重计算的偏差;多层次灰色评价模型对于引水明渠安全运行风险等级的确定较为有效,并得出其风险等级为中等偏高,与实际情况一致。研究成果为引水明渠工程安全运行提供了一定的参考,同时可为类似气候环境的引水明渠区域规划、设计、施工提供有效的借鉴。     

海洋经济发展中的区域经济理论探讨

以江苏沿海经济发展为研究对象,通过分析江苏沿海区域在经历了产业梯度转移理论指导,再引入增长极理论,制定区域海洋经济发展战略.分析了江苏沿海盐城、连云港、南通三市的区位特点,选择三市作为江苏海洋经济发展的增长中心,确定各市的主导产业,最终达到缩小江苏沿海与苏南之间的经济差距,加快江苏海洋经济发展速度,增强江苏海洋经济势力的目的.     

Degradation of chlorinated phenols by nanoscale zero-valent iron

Chlorophenols (CPs), as important contaminants in groundwater, are toxic and difficult to biodegrade. Recently nanoscale zero-valent iron received a great deal of attention because of its excellent performance in treating recalcitrant compounds. In this study, nanoscale zero-valent iron particles were prepared using chemical reduction, and the reductive transformations of three kinds of chlorinated phenols (2-CP, 3-CP, and 4-CP) by nanoscale zero-valent iron under different conditions were investigated. The transformation process of the CPs was shown to be dechlorination first, then cleavage of the benzene ring. The removal efficiency of the CPs varied as follows: 2-CP > 3-CP > 4-CP. The reactivity of CPs was associated with their energy of lowest unoccupied molecular orbit (E _LUMO). With the increase in initial concentrations of CPs, removal efficiency decreased a little. But the quantities of CPs reduced increased evidently. Temperature had influence on not only the removal efficiency, but also the transformation pathway. At higher temperatures, dechlorination occurred prior to benzene ring cleavage. At lower temperatures, however, the oxidation product was formed more easily. __________ Translated from China Environmental Science, 2006, 26(6): 698–702 [译自: 中国环境科学]     

基于弹性理念的城市用地开发战略研究——以上海市宝山区为例

随着市场机制的不断完善,城市土地利用的不确定性需要在战略定位上具备更大的弹性以适应市场的发展。基于弹性理念,在对城市用地开发条件进行辨识的基础上,对土地开发的需求进行了弹性预测,依据人口极限计算出土地弹性需求值域的上下限,确定弹性范围,提出适应社会经济发展需要的用地开发战略目标,并找到将其变为现实的正确途径。在结构上从城市用地开发战略目标的确定、城市用地发展方向的定位以及城市用地模式的选择3个方面,对城市用地开发的战略研究做了深入分析。同时,引入新的思想和方法以及多学科多视角,定性与定量相结合来制定城市用地开发的战略目标。最后,利用上海市宝山区作为实例,对基于弹性理念的城市用地开发战略的研究做了实证分析。     

Optimizing a warranty–based sustainable product service system using game theory

Abstract

In recent years, the concepts of sustainability and product service system have been closely associated with each other. In today’s competitive markets, due to Extended Producer Responsibility and customer environmental awareness, producers shift from ‘product-seller’ towards ‘product-service provider’ for using the environmental and economic advantages of coupling a product with services. This paper proposes a novel approach to determine the optimal warranty period and the out-of-warranty replacement period, from the point of view of the producer and the customer to minimise the total cost of usage and end of life of product. As regards the fact that adopted strategies by producers and customers sometimes are in conflict and it affects choosing the optimal product usage period, a game theory model was developed in this study. Finally, a case study with data from chain of local notebook service centres was applied to demonstrate some practical aspects of the developed model.