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991.
投入产出模型在工业生态系统分析中的应用   总被引:1,自引:0,他引:1  
应用投入产出模型构建出工业生态系统物质流分析的基本框架,在此基础上提出工业生态系统“关键种企业”的识别方法。以及工业生态系统企业能量消耗特征、累计污染排放特征的量化分析方法。这些分析方法将是辅助工业生态系统日常管理与维护的有力工具。  相似文献   
992.
We explore the problem of integrating some of the many factors involved in conservation planning by focusing on their effects on a common currency of conservation success, the probability of persistence. This approach has the potential to reduce many of the difficulties inherent in combining different pattern and process factors. For handling information expressed as probabilities, five area-selection methods are compared.  相似文献   
993.
As most parasitoids are time limited, they usually die before they have laid all their eggs. In such cases, optimal foraging theory predicts that female parasitoids will adopt behavioral reproductive strategies enabling them to maximize progeny production per unit of time. One key situation in which parasitoid females must optimize their time budget is related to the fact that most of their hosts are distributed in discrete patches in the environment. In this review, I first present the results of basic theoretical models predicting female wasp search duration on a patch of hosts. I then compile and analyze all studies investigating the effect of different factors on parasitoid patch time allocation and patch-leaving decision rules. Different patch-leaving mechanisms that were proposed to explain the results obtained are discussed, along with statistical methods that should be used to estimate them from experimental data. Finally, ideas for future research are presented.  相似文献   
994.
We describe the results of an aerosol sampling campaign performedin 1999 in the medium-size industrial town of La Spezia, in theNorthwest of Italy. We used two-stage continuous streakersamplers in three different sites and periods of the year. This kind of samplers allows the separation of the PM10 andPM2.2 fractions of the particulate matter. Moreover, the hourly resolution in the aerosol collection is particularly useful inan urban environment where, typically, many pollution sourceswith fast variations are present. Up to 1700 samples have beenanalysed by Particle Induced X-ray Emission (PIXE) at the INFNaccelerator facility in Florence, obtaining hourly concentrationfor about 20 elements from Na to Pb, with a sensitivity rangingfrom below 1 to about 10 ng m-3. The total hourly aerosolmass has been estimated with an optical analysis of the samesamples performed (before the PIXE analysis) by an equipment designed and mounted in Genoa. An extensive statistical analysisof the data included standard and Absolute Principal ComponentFactor Analysis (PCFA and APCFA) to deduce the compositionand the weight of the major aerosol sources in both fractions.Thorough different statistical approaches, we generally resolvedcontributions from vehicle emission, fossil fuel combustion,soil-road dust and sea salt aerosol.  相似文献   
995.
群体建筑物震害预测是确定一个城市或地区某一类建筑在确定强度或某一确定时期内的地震作用下,发生某种破坏程度的概率,其目的是分析建筑物在遭受不同地震烈度影响时可能产生的破坏。系统梳理了现今为止国内外群体建筑物震害预测的学术研究现状,总结归纳了国内外传统的群体建筑物震害预测方法和近二十年来国内对于传统震害预测方法的改进研究进展,以期为城市群体建筑物震害预测研究提供新的视角和基础资料。  相似文献   
996.
基于改进支持向量机的石煤提钒行业清洁生产评价研究   总被引:1,自引:0,他引:1  
采用遗传算法(GA)对支持向量机(SVM)进行改进,并将其应用于石煤提钒行业清洁生产评价.在系统研究石煤提钒工艺类型的基础上,根据前期已建立的石煤提钒行业清洁生产评价指标体系,提出GA改进SVM的应用思路,通过对3种工艺类型企业的现场数据采集,形成训练和测试样本,并利用GA算法确定出各类参数(惩罚参数C和核函数参数g),分别为强酸浸工艺C=2.1049,g=5.2184;弱酸浸工艺C=0.0035286,g=1.9947;水浸工艺C=0.39587,g=1.4105.GA-SVM模型测试结果表明,分类精度达到100%.通过与其他评价方法对比表明,训练好的GA-SVM方法针对小样本数据在分类精度和可操作性上都较其他方法有明显优势,实现了对石煤提钒行业清洁生产水平的定量评价.  相似文献   
997.
在科技发展时代,低碳经济已经成为世界经济发展的新趋势.如何建设低碳经济,在发展经济,提高人民生活水平,同时应尽量减少对环境的破坏,给子孙万代留下资源,这是经济发展面对的一大难题.低碳会计就是要通过对企业经济活动的财政管理,能够有效实现企业经济结构的优化升级和经济增长方式的转型.为发展低碳经济,做好低碳会计的工作,为低碳经济的发展努力.因此,企业会计应该深入研究在低碳企业中的作用,为提高低碳企业的经济效益、实现低碳企业的发展奋斗.  相似文献   
998.
大气资源是一类重要的"非实物态"自然资源资产。优质大气资源具有重要的生态系统服务价值,对人类生存发展起着至关重要的作用。目前,深圳市已将大气资源纳入自然资源资产负债表账户,但其生态系统服务价值尚未有系统性的量化核算方法,给自然资源资源资产负债表填报及领导干部离任审计等工作带来极大困难。本文在分析2015年深圳市大气环境质量现状的基础上,分别采用条件价值法、治理成本法及健康损害法对三类不同AQI等级的深圳市大气资源价值进行了初步核算,从而构建了大气环境质量价值核算体系。该体系可为深圳市大气资源资产负债表填制及领导干部离任审计提供技术支撑,同时为大气资源质量改善和治理提供管理依据,也为其他地区大气资源价值核算提供技术参考。  相似文献   
999.
Urban public spaces are important areas for leisure, recreation and physical activity and therefore contribute to the quality of life in cities. In particular, for adolescents they provide important spaces to meet with their peers, away from parental or school control. In many cities worldwide, public spaces have undergone severe developmental processes, and often a withdrawal from public space is noted. With regard to the opportunities those spaces provide for adolescents, it is necessary to investigate their current meaning for adolescents in a leisure context. In this article, qualitative research methods were used to investigate factors affecting adolescents’ use of public spaces in Vienna, Austria. In total 45 adolescents were interviewed. Results show that public open spaces are not regarded as important leisure spaces, and data reveal a strong retreat to private areas for leisure purposes. Perceived insecurities and fears support these processes and often result in avoidance of public spaces but also the wish for more control by authorities.  相似文献   
1000.
Objective: In 2012 in the United States, pedestrian injuries accounted for 3.3% of all traffic injuries but, disproportionately, pedestrian fatalities accounted for roughly 14% of traffic-related deaths (NHTSA 2014 NHTSA. Traffic Safety Facts 2012 Pedestrians. Washington, DC: Author; 2014. DOT HS 811 888. [Google Scholar]). In many other countries, pedestrians make up more than 50% of those injured and killed in crashes. This research project examined driver response to crash-imminent situations involving pedestrians in a high-fidelity, full-motion driving simulator. This article presents a scenario development method and discusses experimental design and control issues in conducting pedestrian crash research in a simulation environment. Driving simulators offer a safe environment in which to test driver response and offer the advantage of having virtual pedestrian models that move realistically, unlike test track studies, which by nature must use pedestrian dummies on some moving track.

Methods: An analysis of pedestrian crash trajectories, speeds, roadside features, and pedestrian behavior was used to create 18 unique crash scenarios representative of the most frequent and most costly crash types. For the study reported here, we only considered scenarios where the car is traveling straight because these represent the majority of fatalities. We manipulated driver expectation of a pedestrian both by presenting intersection and mid-block crossing as well as by using features in the scene to direct the driver's visual attention toward or away from the crossing pedestrian. Three visual environments for the scenarios were used to provide a variety of roadside environments and speed: a 20–30 mph residential area, a 55 mph rural undivided highway, and a 40 mph urban area.

Results: Many variables of crash situations were considered in selecting and developing the scenarios, including vehicle and pedestrian movements; roadway and roadside features; environmental conditions; and characteristics of the pedestrian, driver, and vehicle. The driving simulator scenarios were subjected to iterative testing to adjust time to arrival triggers for the pedestrian actions. This article discusses the rationale behind creating the simulator scenarios and some of the procedural considerations for conducting this type of research.

Conclusions: Crash analyses can be used to construct test scenarios for driver behavior evaluations using driving simulators. By considering trajectories, roadway, and environmental conditions of real-world crashes, representative virtual scenarios can serve as safe test beds for advanced driver assistance systems. The results of such research can be used to inform pedestrian crash avoidance/mitigation systems by identifying driver error, driver response time, and driver response choice (i.e., steering vs. braking).  相似文献   
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