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151.
Cycling index is an important ecological indicator used in ecosystem analysis. The higher the cycling in an ecosystem, the higher the utilization of mass and energy within the system before it is lost due to respiration and other factors. For a stock-flow type ecosystem model at steady state, Finn’s cycling index (FCI) can be computed using simple matrix algebra. However, it is difficult to measure how well this index represents the actual cycling occurring in the system. In this paper, we study cycling in ecological networks using an individual based approach (particle tracking algorithm). This new simulation method provides access to the pathway data of individual particles that flow in the system, therefore one can quantify cycling using this pathway data quite literally. We used particle tracking simulations (PTS) to compute a cycling index using Finn’s idea of flux based cycling. Our simulation based results (using no matrix algebra) agree with Finn’s cycling index, verifying the accuracy of both the PTS, and the original linear algebraic formulation of FCI.  相似文献   
152.
We present a method of multi-criteria assessment for the analysis of process model uncertainty that combines analysis of model structure, parameters and data requirements. There are three components in calculation and definition of uncertainty.
(1)
Assessment criteria: Uncertainty in a process model is reduced as the model can simultaneously simulate an increased number of assessment criteria selected to test specific aspects of the theory being investigated, and within acceptable limits set for those criteria. This reduces incomplete specification of the model—the characteristic that a model may explain some, but not all, of the observed features of a phenomenon. The calculation required is computation of the Pareto set which provides the list of simultaneously achieved criteria within specified ranges.  相似文献   
153.
154.
This paper explores the crucial part that faith‐based organisations (FBOs) play in acting as intermediaries between international donors and local faith communities (LFCs) implementing humanitarian relief projects for Syrian refugees. Humanitarian responses to the mounting Syrian refugee crisis have coincided with greater collaboration between international donors and LFCs. This cooperation often is facilitated by a complex web of non‐state intermediaries at the international, national, and local level. This study probes the breadth of roles of these intermediaries, drawing on primary data from case studies of two Christian intermediaries supporting Christian LFCs as they deliver aid primarily to Muslim Syrian refugees in Jordan and Lebanon. The results of the study are connected to the wider literature on LFCs in humanitarian response, revealing how intermediaries address issues of accountability, capacity‐building, impartiality, neutrality, and professionalism. The paper concludes by offering suggestions for further research on intermediaries as key actors in the localisation of humanitarian assistance.  相似文献   
155.
Ecology-based tourism, which is integrated with nature, developed in environmentally conscious areas and enriched by different cultures, has become more important in the direction of extending tourism throughout the year. While the landscape values of the area are important functions for tourism activities to be carried out in natural characteristics, the preferences of the users are also important. Ecology-based tourism, which develops in connection with the concepts of intacteness, the protection-use balance and sustainability, and the demands and expectations of tourists, constitute the basis of our study. For this purpose, the study was carried out in Kumyaka, a small coastal neighborhood (village) of the county of Mudanya in the province Bursa, Turkey with important natural, historical and cultural assets. Fieldwork, field analysis, literature search, interviews with tourists coming to the field, interviews with the day trippers and survey work were conducted in the study. While evaluating the ecology-based tourism potential of the area, the demands and expectations of tourists have been taken into account together with the available area data. According to the results of the survey, tourists are mostly interested in having the most scenic value and quietness when choosing the area. The types of tourism that tourists most wanted to experience in the field were 42.38% culture tourism and 32.32% nature tourism. As a result of tourists’ demands and expectations, the tourism activities to be carried out in accordance with the possibilities of the area were examined and ecology based planning proposals and holistic planning approaches were developed.  相似文献   
156.
上海市突发环境污染事故风险区划   总被引:5,自引:0,他引:5       下载免费PDF全文
薛鹏丽  曾维华 《中国环境科学》2011,31(10):1743-1750
环境风险区划是区域布局型环境风险管理及环境风险分区管理的重要手段.本研究在环境风险系统理论的指导下,借鉴“自上而下”和“自下而上”传统区划方对上海市突发环境风险进行区划研究.上海市突发环境风险区划中“自上而下”环境风险一级区的划分是依据上海市1990~2008年突发污染事故历史时空格局获得;而“自下而上”是通过构建上海市风险区划指标体系,在对指标进行概念模型量化的基础上,运用基于遗传算法的K均值聚类在最小区划单元进行聚类区划,并依据上海市政府宏观规划对聚类后的图斑碎块进行科学性和实用性调整,获得上海市突发环境污染事故风险亚区和小区;将上海市突发环境风险一级区及亚区和小区集成分析,实现上海市突发环境污染事故风险综合区划.结果表明:上海市突发环境污染事故风险区划包含2个风险一级区,5个风险亚区和21个风险小区,客观揭示了上海市突发环境污染事故风险的空间分布规律.针对上海市布局型环境风险和不同风险区提出相应的管理措施,为上海市综合减灾降险和风险管理决策提供科学依据.  相似文献   
157.
以钼尾矿为原料,采用酸溶—碳酸钾沉淀法制备硅微粉。考察了反应温度、反应时间、K2CO3质量分数对产品中SiO2质量分数和SiO2产率的影响。得到的优化工艺条件为:钼尾矿粒径小于74 μm,反应温度50 ℃,反应时间60 min,K2CO3质量分数50%。在此工艺条件下,SiO2产率可达98.92%,产品硅微粉的SiO2质量分数达98.44%,粒径为100~200 nm,超过中华人民共和国黑色冶金行业标准《不定型耐火材料用二氧化硅微粉》(YB/T 115—2004)中SF96指标(SiO2质量分数≥96.0%)的要求。  相似文献   
158.
Toxicokinetic-toxicodynamic (TKTD) models simulate the time-course of toxicant concentration in the organism and toxicity at the level of the organism. A link between TKTD models that simulate survival and individual based models for populations (IBMs) is proposed which allows TKTD parameters to vary between individuals. The TKTD-IBM predicts different survival in response to toxicants when TKTD parameters vary amongst individuals compared to the survival predicted with fixed TKTD parameters. The model with fixed parameters represents the concept of stochastic death whereas the model with variable parameters behaves, at least partly, according to the individual tolerance distribution concept. The whole set of TKTD parameters of an individual can be interpreted as constituting “individual tolerance”.  相似文献   
159.
采用将脱硫剂搭载在多孔的玻璃棉上,避免了传统的流化过程所导致的脱硫剂的磨损和破碎.分析了蒸汽活化后脱硫剂孔隙结构的变化,证实了中温条件下蒸汽活化改善了孔的结构,增加了中孔的数量,并使脱硫剂发生明显的破碎,从而减弱了产物层的扩散阻力,使SO2和CaO的接触和反应变得有利.并证实了对脱硫反应贡献最大的是100~5000nm的中孔,而不是导致比表面积迅速增加的微孔,同时还发现,600℃时的脱硫反应比300℃情况下使脱硫剂产生更大量的破碎,导致更多的孔间隙.因此从物理结构上也解释了脱硫反应在600℃时的钙利用率要高于300℃时的情况.  相似文献   
160.
资源型城市可持续竞争力的培育--以山西省大同市为例   总被引:1,自引:0,他引:1  
首先对我国资源型城市的倒“U”型发展现象进行解析,接着分析了我国资源型城市存在的主要问题,并对资源型城市的可持续竞争力构建进行了概述,然后通过案例分析的方式,分析了资源型城市在同等规模城市中的可持续竞争能力。最后根据资源型城市的类型分别提出了培育其城市可持续竞争力的对策。  相似文献   
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