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141.
Rainfall is an important factor in estimating the event mean concentration (EMC) which is used to quantify the washed-off pollutant concentrations from non-point sources (NPSs). Pollutant loads could also be calculated using rainfall, catchment area and runoff coefficient. In this study, runoff quantity and quality data gathered from a 28-month monitoring conducted on the road and parking lot sites in Korea were evaluated using multiple linear regression (MLR) to develop equations for estimating pollutant loads and EMCs as a function of rainfall variables. The results revealed that total event rainfall and average rainfall intensity are possible predictors of pollutant loads. Overall, the models are indicators of the high uncertainties of NPSs; perhaps estimation of EMCs and loads could be accurately obtained by means of water quality sampling or a long term monitoring is needed to gather more data that can be used for the development of estimation models.  相似文献   
142.
In a case study that examines the outcomes of a flexible information-based policy, we observe how organizations obtain Leadership in Energy and Environmental Design certification. We use a regression discontinuity analysis to identify practices used to upgrade certification tiers. This analysis reveals preferences for green certification strategies and, we argue, intimates the perceived motivations for green certification. We distinguish practices that potentially confer private gains through returns to efficiency and productivity investments, from practices that only provide public benefits. Data show that organizations strategically certify to avoid high-cost resource use, appeal to key stakeholders, and communicate building and organization quality. Builders upgrading to the highest tiers are more likely to deploy practices with private gains. Results suggest a willingness to extend short time horizons associated with energy-efficiency investments in exchange for marketing benefits. Our discussion notes the capacity for certifications to mitigate market barriers associated with the energy-efficiency gap.  相似文献   
143.
为了准确地检测城市燃气管道泄漏,提出了一种基于广义概念的管道泄漏检测定位方法。声发射技术对于管道泄漏的检测、定位是一个极好的工具,但由于泄漏源的传播容易受到周围背景噪声以及复杂工况的影响,其定位误差较大。基于时延估计的互相关信号处理方法被广泛用于管道泄漏检测定位,但由于泄漏应力波传播通道的动态特性,使得源信号在传播过程中会产生波形变化,给互相关函数峰值位置的确定带来困难。由此引入广义相关分析方法,通过对信号进行前置滤波,在一定程度上减少了传播通道动态特性因素对泄漏点定位的不利影响,得到了更为准确的时延估值。在此基础上,通过模拟实验,编写Matlab神经网络代码,构造GRNN模型,进一步预测定位。结果表明,GRNN预测的声发射检测值、互相关定位值以及广义相关定位值,相比之前定位精度分别得到提高,其中基于广义相关的延时估计方法定位最为精确,将该方法用于工程实际中,可以更加精确地定位出泄漏点。  相似文献   
144.
为监测预警尾矿坝的变形位移,提出基于结构风险最小化理论的支持向量机进行学习预测。通过采集有效数据,对时间序列数据进行归一化序列处理,然后采取种族鱼群选择向量机参数,对处理后的数据进行支持向量机回归预测。将该理论应用到某尾矿坝监测系统,得到了较为准确的预测结果,表明该理论充分利用了数据的统计特性,精度和泛化能力都得到了明显提高,可作为尾矿坝监测系统的有效指导。  相似文献   
145.
Objective: An increasing number of motorcycle taxis have been involved in traffic crashes in many developing countries. This study examines the characteristics of both motorcycle taxi drivers and nonoccupational motorcyclists, investigates the risks they pose to road safety, and provides recommendations to minimize their risks.

Methods: Based on the data collected from a questionnaire survey of 867 motorcycle taxi drivers and 2,029 nonoccupational motorcyclists in Maoming, South China, comparisons were made to analyze differences of personal attributes, attitudes toward road safety, and self-reported behavior of the 2 groups.

Results: Results of the chi-square tests show that not only motorcycle taxi drivers but also nonoccupational motorcyclists in Maoming held poor attitudes toward road safety and both groups reported unsafe driving behavior. There is much room for improving local road safety education among all motorcyclists in Maoming. Yet, motorcycle taxi drivers were more likely to pose road safety risks than nonoccupational motorcyclists under some circumstances, such as speeding late at night or early in the morning, not requiring passengers to wear helmets, and running a red light. The results of the binary logistic regression model show that possessing a vehicle license for a motorcycle or not was the common significant predictor for unsafe driving behavior of motorcycle taxi drivers and nonoccupational motorcyclists. Therefore, enforcement against all motorcyclists not showing vehicle licenses for their motorcycles should be stepped up.

Conclusion: Motorcycle safety is largely poor in Maoming. Therefore, efforts to improve motorcycle safety should be strengthened by targeting not only motorcycle taxi drivers but also nonoccupational motorcyclists.  相似文献   

146.
147.
PM2.5在地球表面上的变化是连续的,但由于地面海拔起伏和站点分布的相对稀疏,直接内插法很难顾及这种情况。文章运用反距离权重(IDW)、Kriging、经验贝叶斯克里金法(EBK)、多元回归+残差内插的综合空间化手段,对北京市2015年1月的PM2.5数据进行分析。结果表明:利用多元回归+残差内插方法空间化更优,且PM2.5存在显著的正局部空间自相关,中度以上污染主要分布在北京市东南部和房山区。时间上,PM2.5质量浓度逐时均值呈"W"型。3 h尺度上,PM2.5质量浓度与相对湿度和露点温度正相关,与能见度、大气压和风速负相关,与温度不相关。  相似文献   
148.
以某铀尾矿库为例,应用层次分析法(AHP)对DRASTIC进行了改进,并增加两个新的指标,得出改进后的AHPDRASTICLL模型。分别采用常规DRASTIC模型、改进DRASTICLL模型、AHP-DRASTICLL模型对某铀尾矿库区地下水受U(Ⅵ )污染风险进行了评价。结果表明:尾矿库周围与砂卵砾石层区风险较高,丘陵地带风险较低。采集监测井U(Ⅵ )浓度样本数据,与3个模型标准化综合评分值建立线性回归关系,常规DRASTIC模型相关系数R2=0.7795;改进DRASTICLL模型相关系数R2=0.8278;AHP-DRASTICLL模型相关系数R2=0.8581。分析结果表明AHPDRASTICLL模型能更加准确地反映地下水受污染的可能性。  相似文献   
149.
定量研究水生生物对水环境参数的适宜值是评估栖息地质量和维持生物完整性的主要途径. 以辽宁省太子河流域为研究范例,选择Y(优势度指数)大于0.000 1的硅藻为研究对象,结合水环境参数,采用CCA(典范对应分析)、CART(分类回归树)和WA(加权平均回归分析)等方法,分析硅藻与水环境因子的关系,并计算硅藻对驱动因子的最适值. CCA结果表明,IOS(底质指数)、ρ(TDS)(TDS为总溶解固体)和ρ(CODMn)是硅藻群落的驱动因子;CART预测结果表明,IOS高的水环境硅藻密度高于IOS低的水环境,ρ(TDS)和ρ(CODMn)低的水环境硅藻密度高于ρ(TDS)和ρ(CODMn)高的水环境;WA结果显示,96种硅藻对IOS、ρ(TDS)和ρ(CODMn)的最适值范围分别为1.00~6.44、60.29~820.30 mg/L和0.46~2.89 mg/L. 钝端菱形藻解剖刀变种和尖端菱形藻适宜栖息于IOS较低而ρ(CODMn)较高的水环境, Gomphonema trancatum和肿大桥弯藻则适宜栖息于IOS较高的水环境;缠结异极藻二叉变种和尖细异极藻适宜栖息于ρ(TDS)较高的水环境,弧形峨眉藻和克洛钝脆杆藻则适宜栖息于ρ(TDS)较低的水环境;弧形峨眉藻和隐头舟形藻威蓝变种适宜栖息于ρ(CODMn)较低的水环境. 针杆藻和桥弯藻对IOS的最适值高于舟形藻和菱形藻以及其他藻种,96种硅藻对ρ(TDS)和ρ(CODMn)的最适值均表现为菱形藻和异极藻较高、针杆藻和桥弯藻较低.   相似文献   
150.
Beaches are a unique type of recreation setting, offering a variety of water- and land-based opportunities that can meet residents’ diverse and complex recreation needs. Providing and improving equitable access to recreation amenities such as beaches have been recognized as essential responsibilities of public leisure agencies. This study assessed the degree of equity inherent in the distribution of public beaches in the Detroit metropolitan area; to account for spatial effects, phenomena rarely considered in prior equity analyses, geographically weighted regression was employed. Considerable local variations in the relationships between level of access to public beaches and population density, proportion of elderly population and educational attainment were identified. Such findings can help parks and recreation agencies better understand local patterns of equity, an important first step in facilitating the formulation of more efficient and effective planning and policy approaches.  相似文献   
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