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391.
392.
G. Grabow D. C. Yoder C. R. Mote 《Journal of the American Water Resources Association》2000,36(3):549-566
ABSTRACT: A procedure using a simple, empirically‐based model that makes efficient use of available information has been developed for designing a ground water monitoring well network. A moving plume is described by siting wells in a sequential manner, relying upon two‐dimensional concentration data obtained from previously installed wells to determine the locations of future wells. Data sets from two well known, densely monitored natural gradient tracer studies were used to test the procedure. Plumes defined by all information in the original networks were compared to those defined by reduced networks designed by the new procedure. The new procedure tracked the plumes using only a portion of that information. The new procedure could have reduced the number of wells in the original tests by about 50 percent without appreciable loss of plume information as measured by plume location and extent and by tracer mass. 相似文献
393.
介绍了锡矿山矿务局北矿童家院区北风井通风系统建立的过程,对北风井通风系统投产运行的实际效果进行了评价. 相似文献
394.
Ecological network analysis (ENA) is a modeling approach increasingly being used to evaluate food webs and provide an ecosystem-based approach to resource management. Unfortunately, validation of ENA output is rarely performed. This study represents part of a larger effort to critically evaluate ENA. Here we validate ENA output using stable isotope analysis (SIA), and where validation is not met, determine the effects of modifying trophic networks to reflect validation. 相似文献
395.
为了在矿井通风网络发生阻变型故障时,能够快速准确判断出故障位置和故障量,提出1种基于随机森林的通风网络故障位置和故障量诊断方法。利用矿井通风仿真系统IMVS将唐安矿模拟故障生成空间数据集并进行数据预处理,构建基于随机森林的故障诊断模型,并利用该诊断模型对唐安矿矿井通风网络模拟故障位置和故障量进行判断和预测。引用多种方法对模型进行度量,通过唐安矿模拟实验验证基于随机森林的故障诊断模型的有效性。将随机森林和决策树的故障诊断准确率进行对比,研究结果表明:随机森林较决策树故障准确率有进一步的提高,并发现故障地点失误诊断多是相邻巷道,在一定程度上工作人员对故障地点的判断并不受其影响。 相似文献
396.
CHI Yong WEN Jun-ming ZHANG Dong-ping YAN Jian-hu NI Ming-jiang CEN Ke-fa 《环境科学学报(英文版)》2005,17(4):699-704
IntroductionWiththedepletionofspaceforlandfillingofmunicipalsolidwasteandtherisingpricesforrawmaterials ,moreandmorefluidizedbedincineratorshavebeenusedtotreatMSWduetotheprimaryadvantagesofhygieniccontrol,volumereductionandenergyrecovery .BecausetheMSWhas… 相似文献
397.
氯代芳香族化合物结构-电化学还原电位定量关系的贝叶斯规整化BP神经网络模型 总被引:8,自引:1,他引:7
将贝叶斯规整化误差反向传播神经网络(BRBPNN)应用于环境领域的 QSPR模型.采用ChemOffice2004内置的MOPAC 2000计算了6种量子化学参数(分子最高占据能EHOMO、分子最低占据能ELUMO、分子生成热HF、分子偶极矩DIP、分子的电子能量EE和分子的核核排斥能CCR)以及氯原子数(Cl)和分子量(MW),建立了87种氯代芳香族化合物结构与电化学还原电位定量关系的BRBPNN模型.最优网络模型结构为6-20-1,其电化学还原电位的拟合及预测能力明显优于逐步线性回归模型,其训练集和预测集的相关系数平方和均方根误差(MSE)分别达到0.999和0.000105,0.965和 0.00159.最优模型输入节点到隐含层权重平方和的分布规律揭示出各种描述符对还原电位的影响大小依次为: ELUMO>EHOMO>HF>CCR>EE>DIP.由散点图揭示出影响为正有EE;影响为负有ELUMO,HF,DIP;影响无明显正负性的有ELUMO,CCR.结果表明,贝叶斯规整化大大方便了网络规整化参数选择,保证了网络的优良概括能力和稳健性.本研究对氯代芳香族化合物采用电化学处理的适用性以及分析相应电化学降解机理提供了依据. 相似文献
398.
399.
Source characterization of ambient fine particles at multiple sites in the Seattle area 总被引:2,自引:0,他引:2
To identify major PM2.5 (particulate matter ≤2.5 μm in aerodynamic diameter) sources with a particular emphasis on the ship engine emissions from a major port, integrated 24 h PM2.5 speciation data collected between 2000 and 2005 at five United State Environmental Protection Agency's Speciation Trends Network monitoring sites in Seattle, WA were analyzed. Seven to ten PM2.5 sources were identified through the application of positive matrix factorization (PMF). Secondary particles (12–26% for secondary nitrate; 17–20% for secondary sulfate) and gasoline vehicle emissions (13–31%) made the largest contributions to the PM2.5 mass concentrations at all of the monitoring sites except for the residential Lake Forest site, where wood smoke contributed the most PM2.5 mass (31%). Other identified sources include diesel vehicle emissions, airborne soil, residual oil combustion, sea salt, aged sea salt, metal processing, and cement kiln. Residual oil combustion sources identified at multiple monitoring sites point clearly to the Port of Seattle suggesting ship emissions as the source of oil combustion particles. In addition, the relationship between sulfate concentrations and the oil combustion emissions indicated contributions of ship emissions to the local sulfate concentrations. The analysis of spatial variability of PM2.5 sources shows that the spatial distributions of several PM2.5 sources were heterogeneous within a given air shed. 相似文献
400.
To date, many water quality monitoring networks for surface freshwaters have been rather haphazardly designed without a consistent or logical design strategy. Moreover, design practices in recent years indicate a need for cost-effective and logistically adaptable network design approaches. There are many variables that need to be included in a comprehensive yet practical monitoring network: a holistic appraisal of the monitoring objectives, representative sampling locations, suitable sampling frequencies, water quality variable selection, and budgetary and logistical constraints are examples. In order to investigate the factors which affect the development of an effective water quality monitoring network design methodology, a review of past and current approaches is presented. 相似文献