共查询到20条相似文献,搜索用时 561 毫秒
1.
基于BP网络的水质综合评价模型及其应用 总被引:18,自引:0,他引:18
讨论了BP网络模型存在的不足及建模条件,提出了建立合理的BP网络模型的基本原则和步骤。针对水质评价问题,通过在各类水质污染指标浓度区间内生成随机分布样本的方法,组成足够多用于BP网络训练、检验和测试用的样本,建立了辽河水质综合评价的BP网络模型;给出了区分不同类别水质的模型分界值样本和模型输出分界值。 相似文献
2.
3.
4.
5.
6.
7.
基于灰色模型和模糊神经网络的综合水质预测模型研究 总被引:2,自引:0,他引:2
水质状态变化趋势预测研究对水资源管理和维护具有重要的现实意义。提出了一种将灰色模型和模糊神经网络相结合的水质预测模型。首先基于改进的灰色模型预测出水体中各理化因子在未来一段时间内的指标变化,然后采用T-S模糊神经网络对各单因子的预测值进行数据融合,构建水质变化综合趋势预测模型,预测出下一时间段的水质整体状态指标。实验表明,这种方式用来预测湖泊水质变化趋势具有可行性;与BP网络模型相比,基于T-S模糊神经网络系统的模型具有预测精度高、模型系统稳定等优越性。 相似文献
8.
9.
10.
基于径向基函数网络的溢油预测模型 总被引:1,自引:0,他引:1
为了提高溢油预测的准确性,建立和优化溢油预测模型,提出了基于径向基函数网络模型的溢油预测方法,实现溢油预测功能。径向基函数网络模型解决了模拟预测过程中样本库巨大、函数模型收敛速度慢的问题。通过选择有效的输入参数和样本数据,建立局部逼近网络;通过径向基函数训练样本数据,利用输出值与实际值之间的误差作为约束条件调整权重因子、径向基中心和宽度,加快函数模型的收敛速度。该模型模拟了溢油的漂移、扩散过程,达到预测的目的。利用该模型,建立了溢油预测模块,并针对一次溢油事故进行预测模拟,验证了该模型的可行性,能够为应急决策提供一定的支持。 相似文献
11.
Mathew M Yao Y Cao Y Shodhan K Ghosh I Bucci V Leitao C Njoka D Wei I Hellweger FL 《Environmental pollution (Barking, Essex : 1987)》2011,159(8-9):1996-2002
The objective of this study was to characterize and understand the water quality of Boston's Muddy River prior to restoration, to help guide those activities and evaluate their success. We use a combination of monitoring, data analysis and mathematical modeling. The seasonal pattern of temperature, pollutant signatures (identified using a principal component analysis), correlations with precipitation and spatial patterns all point to a significant wastewater input at one of the outfalls and suggest significant receiving water impact. However, a quantitative analysis using a mathematical model (QUAL2K) suggests this source is not significant. Rather, internal loading from algae, sediment bed and waterfowl dominate the spatial pattern of water quality. These results suggest significant improvement can be expected from planned sediment dredging. The paper provides a case study of water quality assessment in the context of urban river restoration, and it illustrates the utility of combining monitoring and data analysis with modeling. 相似文献
12.
13.
14.
未确知测度模型用于水环境质量评价具有合理性。为使模型更加完善,提出将未确知测度模型建立过程标准化,使其具有通用性。并针对水质评价指标众多致评价过程复杂、计算量大的情况,利用MATLAB软件将标准化后的未确知测度模型设计为既定的程序,依靠计算机模拟来实现水质评价。通过对浮桥河水库水质的评价结果及与其他多种方法的对比,表现出标准化模型的客观性、合理性,MATLAB程序的实用性、快捷性。程序化的未确知测度模型标准化后可进行推广。 相似文献
15.
本文针对嫩江沿岸采用氧化塘处理污水的特点,为充分合理利用水环境容量,以流域总量控制的原则为指导,建立了水污染物总量分配模型,预测不同流量和不同排污情况下的水质,确定不同流量下给定水质目标的临界距离和允许排污量。 相似文献
16.
Schaub M Emberson L Büker P Kräuchi N 《Environmental pollution (Barking, Essex : 1987)》2007,145(3):636-643
The objective of this study was to establish whether EU and UN-ECE/ICP-Forests monitoring data (i) provide the variables necessary to apply the flux-based modeling methods and (ii) meet the quality criteria necessary to apply the flux-based critical level concept. Application of this model has been possible using environmental data collected from the EU and UN-ECE/ICP-Forests monitoring network in Switzerland and Italy for 2000-2002. The test for data completeness and plausibility resulted in 6 out of a possible total of 20 Fagus sylvatica L. plots being identified as suitable from Switzerland, Italy, Spain, and France. The results show that the collected data allow the identification of different spatial and temporal areas and periods as having higher risk to ozone than those identified using the AOT40 approach. However, it was also apparent that the quality and completeness of the available data may severely limit a complete risk assessment across Europe. 相似文献
17.
Sullivan TJ Turner RS Charles DF Cumming BF Smol JP Schofield CL Driscoll CT Cosby BJ Birks HJ Uutala AJ Kingston JC Dixit SS Bernert JA Ryan PF Marmorek DR 《Environmental pollution (Barking, Essex : 1987)》1992,77(2-3):253-262
Because of the considerable uncertainties associated with modeling complex ecosystem processes, it is essential that every effort be made to test model performance prior to relying on model projections for assessment of future surface water chemical response to environmental perturbation. Unfortunately, long-term chemical data with which to validate model performance are seldom available. The authors present here an evaluation of historical acidification of lake waters in the northeastern United States, and compare historical changes in a set of lakes to hindcasts from the same watershed model (MAGIC) used to estimate future changes in response to acidic deposition. The historical analyses and comparisons with MAGIC model hindcasts and forecasts of acid-base response demonstrate that the acidic and low-ANC lakes in this region are responsive to strong acid inputs. However, the model estimates suggest lakewater chemistry is more responsive to atmospheric inputs of sulfur than do the estimates based on paleolimnological historical analyses. A 'weight-of-evidence approach' that incorporates all available sources of information regarding acid-base response provides a more reasonable estimate of future change than an approach based on model projections alone. The results of these analyses have important implications for predicting future surface water chemical change in response to acidic deposition, establishing critical loads of atmospheric pollutants, and other environmental assessment activities where natural variation often exceeds the trends under investigation (high noise-to-signal ratio). Under these conditions, it is particularly important to evaluate future model projections in light of historical trends data. 相似文献
18.
Chemel C Sokhi RS Dore AJ Sutton P Vincent KJ Griffiths SJ Hayman GD Wright RD Baggaley M Hallsworth S Prain HD Fisher BE 《Journal of the Air & Waste Management Association (1995)》2011,61(11):1236-1245
Contributions of the emissions from a U.K. regulated fossil-fuel power station to regional air pollution and deposition are estimated using four air quality modeling systems for the year 2003. The modeling systems vary in complexity and emphasis in the way they treat atmospheric and chemical processes, and include the Community Multiscale Air Quality (CMAQ) modeling system in its versions 4.6 and 4.7, a nested modeling system that combines long- and short-range impacts (referred to as TRACK-ADMS [Trajectory Model with Atmospheric Chemical Kinetics-Atmospheric Dispersion Modelling System]), and the Fine Resolution Atmospheric Multi-pollutant Exchange (FRAME) model. An evaluation of the baseline calculations against U.K. monitoring network data is performed. The CMAQ modeling system version 4.6 data set is selected as the reference data set for the model footprint comparison. The annual mean air concentration and total deposition footprints are summarized for each modeling system. The footprints of the power station emissions can account for a significant fraction of the local impacts for some species (e.g., more than 50% for SO2 air concentration and non-sea-salt sulfur deposition close to the source) for 2003. The spatial correlation and the coefficient of variation of the root mean square error (CVRMSE) are calculated between each model footprint and that calculated by the CMAQ modeling system version 4.6. The correlation coefficient quantifies model agreement in terms of spatial patterns, and the CVRMSE measures the magnitude of the difference between model footprints. Possible reasons for the differences between model results are discussed. Finally, implications and recommendations for the regulatory assessment of the impact of major industrial sources using regional air quality modeling systems are discussed in the light of results from this case study. 相似文献
19.
Aquifer storage and recovery (ASR) is part of the solution to the global problem of managing water resources to meet existing and future freshwater demands. However, the metaphoric "ASR bubble" has been burst with the realization that ASR systems are more physically and chemically complex than the general conceptualization. Aquifer heterogeneity and fluid-rock interactions can greatly affect ASR system performance. The results of modeling studies and field experiences indicate that more sophisticated data collection and solute-transport modeling are required to predict how stored water will migrate in heterogeneous aquifers and how fluid-rock interactions will affect the quality of stored water. It has been well-demonstrated, by historic experience, that ASR systems can provide very large volumes of storage at a lesser cost than other options. The challenges moving forward are to improve the success rate of ASR systems, optimize system performance, and set expectations appropriately. 相似文献
20.
Ethylene oxide (EO) is mainly used as a chemical intermediate and as a fumigant and sterilizing agent. Through its manufacturing and intended uses, EO may be released into the environment. Therefore, an assessment of the environmental significance of those potential emissions was conducted. Data were collected describing pertinent physical properties, degradation and other loss mechanisms that control the fate of EO in the environment. Available aquatic and terrestrial ecotoxicity data were assembled and used as the basis of calculating critical toxicity values to characterize hazard. Environmental compartment concentrations of EO were calculated using Level III fugacity-based modeling. Six scenarios were developed to account for different climatic conditions in various portions of the US. Finally, potential regional-scale risks to aquatic and terrestrial wildlife were determined. In the conceptual model that was developed in this assessment, EO diffuses into air, partitions between environmental compartments, is transported out of the different compartments via advection, and undergoes abiotic and biological degradation within each compartment. All known emissions within the continental USA were assumed to enter a modeled region roughly the size of the State of Ohio. Organisms (receptors) were assumed to dwell in both terrestrial and aquatic compartments. Receptors were assumed to include small mammals, soil invertebrates, water column (pelagic) organisms, and sediment benthos. The goal of this assessment was to characterize any potential adverse risks to terrestrial and aquatic wildlife populations. Hazard Quotients (HQ) were calculated by dividing predicted concentrations of EO in air, water, sediment, and soil by their critical toxicity values. Maximum calculated HQ values in air were 1.52x10(-7), in water were 1.17x10(-5), in sediment were 2.25x10(-4), and in soil were 1.37x10(-5). The results of this assessment suggest that EO as currently manufactured and used does not pose adverse risks to aquatic or terrestrial wildlife. In all cases, the HQ values were much less than the maximum desired HQ value of 1.0 (4,400-6,600,000 times), indicating that the potential for diffuse emissions of EO to pose adverse environmental risks is quite low. 相似文献