建设项目环境影响的时间分布

建设项目对生态与环境影响的时间分布是不均匀的。在建设项目建设和运行的不同时段受影响的环境因子不同,数量不等,强弱不均。环境影响时间分布的类型可大致分为:(1)离散不连续分布,包括一次性突发影响,周期性影响、随机影响;(2)连续分布,包括短期影响、长期均匀影响,长期累积影响;(3)永久性不可逆影响。     

背景噪声的测量和用于修正计算的问题分析及建议

在诸多有关噪声排放的标准中，背景噪声的定义在时间和空间位置方面的规定不够完备；相关的测量的规范方法也未对背景噪声的测量作了规定。实际操作上的“非同时性”给背景噪声的测量结果及用于修正均带来一些失准问题。文中分析了这些问题并提出了初步建议。     

膜生物反应器的技术研究

综合论述了膜生物反应器的设计方法,包括确定最佳水力停留时间、污泥停留时间、污泥浓度,经济性分析.     

2017-2019年扬州市大气污染物与儿童呼吸系统门诊量的时间序列分析

收集扬州市2017—2019年大气污染物细颗粒物(PM_(2.5))、二氧化硫(SO_2)、二氧化氮(NO_2)和臭氧(O_3)的日均质量浓度、气象因素(日均温度、相对湿度)以及每日儿童呼吸系统门诊量数据,运用广义相加模型(GAM)进行单污染物和多污染物分析。结果表明,单污染物分析中,大气污染物的质量浓度累积滞后效应均大于单独滞后效应。ρ(PM_(2.5))、ρ(SO_2)和ρ(NO_2)对儿童呼吸系统门诊量影响效应均在累积滞后7 d(lag 07)达到最大值,ρ(O_3)在累积滞后6 d(lag 06)达到最大值。表现为ρ(PM_(2.5))、ρ(SO_2)和ρ(NO_2)在lag 07时,每升高10μg/m~3,儿童呼吸系统门诊量超额危险度分别为0.720%[95%置信区间(95%CI):0.346%～1.095%]、6.955%(95%CI:5.197%～8.743%)和2.133%(95%CI:1.516%～2.754%);ρ(O_3)在lag 06时,每升高10μg/m~3,儿童呼吸系统门诊量超额危险度为1.160%(95%CI:0.873%～1.447%)。多污染物分析中,当引入所有污染物(SO_2+NO_2+O_3)时,PM_(2.5)对儿童呼吸系统门诊量风险影响消失。大气污染物浓度的升高会增加儿童呼吸系统疾病的发生风险,并且其影响存在一定的滞后效应,有必要开展有针对性的大气污染物与儿童呼吸系统疾病的预警研究,保护易感人群,合理分配卫生资源。     

Value of time: Speeding behavior and gasoline prices

‘Value of Time’ (VOT) is a key parameter in economics and policy. This paper presents an alternative method to estimate VOT by analyzing an hourly dataset on drivers speeding behavior as a function of the gasoline price. Our identification strategy is novel as it is based on the intensive margin. In comparison, previous studies reveal VOT on the extensive margin, but choice alternatives have multiple attributes thereby potentially confounding estimates. Consistent with the range of the prior literature, we find a VOT of about 50% of the wage rate and analyze sources of bias from accidents and traffic tickets. These bias functions suggest that previous stated preference VOT estimates are likely downward whereas previous revealed preference estimates are likely upward biased.     

强震作用下地埋结构的数值模型

应用时域边界元法研究了结构 介质动力相互作用问题。假设摩擦遵守库仑定理 ,当入射波足够强时界面会出现局部滑移、分离。由于边界上的区域 (滑移、分离和粘着 )是未知的 ,所以 ,笔者研究的实际上是个复杂的边界非线性问题。该模型对评估和预测地埋结构在动荷载下的安全具有重要的理论价值     

Future prediction & estimation of faults occurrences in oil pipelines by using data clustering with time series forecasting

The world of oil pipelines is subjected to serious issues due to occurrences of toxic spills, explosions and deformations like particle deposition, corrosions and cracks due to the contact of oil particles with the pipeline surface. Hence, the structural integrity of these pipelines is of great interest due to the probable environmental, infrastructural and financial losses in case of structural failure. Based on the existing technology, it is difficult to analyze the risks at the initial stage, since traditional methods are only appropriate for static accident analyses. Nevertheless, most of these models have used corrosion features alone to assess the condition of pipelines. To sort out the above problem in the oil pipelines, fault identification and prediction methods based on K-means clustering and Time-series forecasting incorporated with linear regression algorithm using multiple pressure data are proposed in this paper. The real-time validation of the proposed technique is validated using a scaled-down experimental hardware lab setup resembling characteristics exhibited by onshore unburied pipeline in India. In the proposed work, crack and blockages are identified by taking pressure rise and pressure drop inferred from two cluster assignment. The obtained numerical results from K-means clustering unveils that maximum datasets accumulated range of multiple pressures are within 16.147–10.638 kg/cm², 14.922–12.1674 kg/cm², 2.7645–1.2063 kg/cm² correspondingly. Hence by this final cluster center data, inspection engineers able to estimate the normal and abnormal performance of oil transportation in a simple-robust manner. The developed forecast model successfully predicts future fault occurrences rate followed by dissimilarity rate from clustering results holds the validity of 91.9% when applied to the historical pressure datasets. The models are expected to help pipeline operators without complex computation processing to assess and predict the condition of existing oil pipelines and hence prioritize the planning of their inspection and rehabilitation.     

The use of proactive risk management to reduce emergency service vehicle crashes among firefighters

IntroductionEmergency service vehicle crashes (ESVCs), including rollovers and collisions with other vehicles and fixed objects, are a leading cause of death among U.S. firefighters. Risk management (RM) is a proactive intervention to identifying and mitigating occupational risks and hazards. The goal of this study was to assess the effect of RM in reducing ESVCs. Methods: Three fire departments (A, B and C), representing urban and suburban geographies, and serving medium to large populations, participated in facilitated RM programs to reduce their ESVCs. Interventions were chosen by each department to address their department-specific circumstances and highest risks. Monthly crash rates per 10,000 calls were calculated for each department an average of 28 months before and 23 months after the start of the RM programs. Interrupted time series analysis was used to assess the effect of the RM programs on monthly crash rates. Poisson regression was used to estimate the number of crashes avoided. Economic data from Department A were analyzed to estimate cost savings. Results: Department A had a 15.4% (P = 0.30) reduction in the overall monthly crash rate immediately post-RM and a 1% (P = 0.18) decline per month thereafter. The estimated two-year average cost savings due to 167 crashes avoided was $253,100 (95%CI= $192,355 – $313,885). Department B had a 9.7% (P = 0.70) increase in the overall monthly crash rate immediately post-RM and showed no significant changes in their monthly crash rate. Department C had a 28.4% (P = 0.001) reduction in overall monthly crash rate immediately post-RM and a 1.2% (P = 0.09) increase per month thereafter, with an estimated 122 crashes avoided. Conclusions: RM programs have the potential to reduce ESVCs in the fire service and their associated costs; results may vary based on the interventions chosen and how they are implemented. Practical applications: Risk management may be an effective and broadly implemented intervention to reduce ESVCs in the US fire service.     

典型区域土壤中多环芳烃的污染分布特征

以河南省3类典型工业区域为例,分析研究其土壤中多环芳烃类化合物的种类组成及含量分布特征,结果表明：3类典型工业区域周边土壤中均检出14种PAHs,其中萘、芘、艹屈 、苯并[a]蒽具有较高的检出水平;大型化工企业周边土壤中PAHs的检出率高于油田和工业园区;检出的14种PAHs的总质量比均值,大型化工企业明显高于油田和工业园区;3类典型工业区域土壤中PAHs测定值明显高于背景值,表明土壤已受到PAHs的影响;来源分析表明,PAHs的污染主要源自石油和燃料的燃烧.     

地下水采样方法比对研究

选取3种地下水采样方法开展方法比对研究。通过系统分析监测数据,指出了3种方法所采水样在基本水质参数、无机离子、金属、挥发性有机物以及感官类指标等项目监测上的显著差异,指出了各种方法的适用性并分析原因。结果表明:与贝勒管法、潜水泵法相比,低流速法有效地解决了采样操作过程中易产生的曝气问题;对井内水体扰动较小,降低了水样浊度;减小了井内水位的大幅度泄降,避免了不同层位间污染物的迁移及周边水和井内滞水的交叉污染;节约了场地操作时间和后期污水处理所需花费。因此,低流速法在采取代表性水质样品方面更具方法优势。