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981.
多氯代二苯并呋喃(PCDFs)是一种典型的持久性有机污染物(POPs),光解是其在环境中转化的主要途径.以分子电性距离矢量(Molecular Electronegativity Distance Vector,MEDV)为参数,应用多元线性回归(Multiple Linear Regression,MLR)和偏最小二乘回归(PLSR)对48种PCDFs在云杉针叶和飞灰表面的光解半衰期(t1/2)进行模拟分析,均获得由2个变量所建的定量结构-性质相关(QSPR)模型.多元线性回归结果:建模相关系数(R)分别为0.860和0.836,标准偏差(SD)分别为0.052和0.053,交互检验复相关系数(Rcv)分别为0.839和0.807,外部检验相关系数(Qex)t分别为0.939和0.853;偏最小二乘回归结果:建模相关系数(R)分别为0.857和0.829,交互检验复相关系数(Rcv)分别为0.849和0.807.结果表明,MEDV能较好地表征该类分子的结构信息,所建QSPR模型具有良好的稳定性和预测能力. 相似文献
982.
During the past few decades, construction and demolition (C&D) waste has received increasing attention from construction practitioners and researchers worldwide. A plethora of research regarding C&D waste management has been published in various academic journals. However, it has been determined that existing studies with respect to C&D waste reduction are mainly carried out from a static perspective, without considering the dynamic and interdependent nature of the whole waste reduction system. This might lead to misunderstanding about the actual effect of implementing any waste reduction strategies. Therefore, this research proposes a model that can serve as a decision support tool for projecting C&D waste reduction in line with the waste management situation of a given construction project, and more importantly, as a platform for simulating effects of various management strategies on C&D waste reduction. The research is conducted using system dynamics methodology, which is a systematic approach that deals with the complexity - interrelationships and dynamics - of any social, economic and managerial system. The dynamic model integrates major variables that affect C&D waste reduction. In this paper, seven causal loop diagrams that can deepen understanding about the feedback relationships underlying C&D waste reduction system are firstly presented. Then a stock-flow diagram is formulated by using software for system dynamics modeling. Finally, a case study is used to illustrate the validation and application of the proposed model. Results of the case study not only built confidence in the model so that it can be used for quantitative analysis, but also assessed and compared the effect of three designed policy scenarios on C&D waste reduction. One major contribution of this study is the development of a dynamic model for evaluating C&D waste reduction strategies under various scenarios, so that best management strategies could be identified before being implemented in practice. 相似文献
983.
Simulation of co-incineration of sewage sludge with municipal solid waste in a grate furnace incinerator 总被引:2,自引:0,他引:2
Incineration is one of the most important methods in the resource recovery disposal of sewage sludge. The combustion characteristics of sewage sludge and an increasing number of municipal solid waste (MSW) incineration plants provide the possibility of co-incineration of sludge with MSW. Computational fluid dynamics (CFD) analysis was used to verify the feasibility of co-incineration of sludge with MSW, and predict the effect of co-incineration. In this study, wet sludge and semi-dried sludge were separately blended with MSW as mixed fuels, which were at a co-incineration ratios of 5 wt.% (wet basis, the same below), 10 wt.%, 15 wt.%, 20 wt.% and 25 wt.%. The result indicates that co-incineration of 10 wt.% wet sludge with MSW can ensure the furnace temperature, the residence time and other vital items in allowable level, while 20 wt.% of semi-dried sludge can reach the same standards. With lower moisture content and higher low heating value (LHV), semi-dried sludge can be more appropriate in co-incineration with MSW in a grate furnace incinerator. 相似文献
984.
985.
潮河流域降雨径流事件污染物输出特征 总被引:2,自引:2,他引:0
在半干旱半湿润地区,非点源养分污染的发生主要由降水径流事件驱动,伴随这些短暂脉冲事件流失的养分量决定着一年总的污染排放负荷,因此研究汛期降雨径流事件下水体污染动态特征是半干旱半湿润地区污染负荷模拟及控制的关键.以北京市密云水库上游的潮河流域为研究区域,2018年和2019年汛期进行古北口站和下会站的降雨径流过程水质水量同步监测.结果表明:①监测的3场降雨事件(E1、E2和E3)中,E1的降雨量和强度最大,相应的流量和污染物浓度最高;②不同降雨事件下,污染物浓度及其变化不同.大暴雨事件和暴雨事件(E1、E3)下,总氮(TN)、氨氮(NH4+-N)、硝氮(NO3--N)、总磷(TP)和悬浮物(TSS)的浓度与流量变化过程相似;大雨事件下(E2),总氮(TN)、氨氮(NH4+-N)、总磷(TP)和悬浮物(TSS)的浓度与流量变化过程相似,硝氮(NO3--N)浓度变化与流量相反;③不同降雨事件下,不同形态污染物浓度及其变化不同.降雨侵蚀强烈(E1、E2),颗粒态污染物浓度变化明显,与悬浮物(TSS)呈显著正相关关系;降雨未引起土壤侵蚀(E3),氮磷形态以溶解态氮(TDN)和溶解态磷(TDP)为主,浓度变化主要与流量有关;④不同降雨事件下,不同站点的流量和污染物浓度不同.强降雨侵蚀事件在古北口表现更明显,引起流量和总磷(TP)、悬浮物(TSS)的变化幅度更大.以上结果可以用来确定降雨事件引发的非点源污染物输出特征,为该地区的汛期水质预测与控制提供参考. 相似文献
986.
Xin Li Jun Xie Chuanjia Jiang Jiaguo Yu Pengyi Zhang 《Frontiers of Environmental Science & Engineering》2018,12(5):14
Heterogeneous photocatalysis has long been considered to be one of the most promising approaches to tackling the myriad environmental issues. However, there are still many challenges for designing efficient and cost-effective photocatalysts and photocatalytic degradation systems for application in practical environmental remediation. In this review, we first systematically introduced the fundamental principles on the photocatalytic pollutant degradation. Then, the important considerations in the design of photocatalytic degradation systems are carefully addressed, including charge carrier dynamics, catalytic selectivity, photocatalyst stability, pollutant adsorption and photodegradation kinetics. Especially, the underlying mechanisms are thoroughly reviewed, including investigation of oxygen reduction properties and identification of reactive oxygen species and key intermediates. This review in environmental photocatalysis may inspire exciting new directions and methods for designing, fabricating and evaluating photocatalytic degradation systems for better environmental remediation and possibly other relevant fields, such as photocatalytic disinfection, water oxidation, and selective organic transformations. 相似文献
987.
水资源可持续利用的系统动力学仿真研究 总被引:15,自引:0,他引:15
如何保护城市环境、合理开发利用自然资源,是当今世界所面临的共同问题。针对我国城市资源与环境的特点,要使经济快速,持续发展,必然解决好水资源的持续利用问题。本文以吉林西部地区乾安县为例,应用系统动力学的原理与方法开展了该区水资源可持续利用系统仿真研究,经过政策模拟对比,提出了符合乾安县经济发展的最佳方案。 相似文献
988.
格氏栲种群增长动态预测研究 总被引:31,自引:2,他引:29
以”空间推时间,横向导纵向”方法,建立了格氏栲种群标准生命表、生殖力表,在此基础上运用Leslie种群增长模型,预测了格氏栲种群的动态增长过程,揭示了格氏栲各龄级植株的动态规律;同时采用特征根理论方法,分析格氏栲种群稳定性,并模拟格氏栲种群的可能变化.结果表明:该区格氏栲为缓慢增长型种群,总体上保持相对稳定状态,老龄阶段对干扰不敏感,种子和生长阶段对干扰有较大敏感.讨论认为,本结果可为格氏栲种群的保护和经营管理提供理论依据和信息 相似文献
989.
990.