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691.
从武汉市取缔正三轮摩托车("麻木")的事件出发,简述了正三轮摩托车的污染危害,计算了取缔车辆1年排放的有害物质,通过监测数据说明了对大气环境的影响。 相似文献
692.
Terrance W. Cundy Kenneth N. Brooks 《Journal of the American Water Resources Association》1981,17(5):775-782
The Streamflow Synthesis and Reservoir Regulation (SSARR) model was calibrated and verified on the Madison and Gallatin watersheds in the upper Missouri River drainage. The study was performed to determine if the SSARR model could simulate snowmelt-runoff volumes to effect better operation of six multipurpose reservoirs on the Missouri River. Physical watershed characteristics and parameter sensitivity are incorporated into a procedure which expedites model calibration. Criteria are established to facilitate parameter development and to objectively evaluate calibration and verification results. A ratio of simulated to observed snowmelt-runoff volumes of the Madison River averaged 1.00 and 1.02 for calibration (N = 8 years) and verification (N = 6 years) with corresponding standard deviations of 0.08 and 0.13. Gallatin volume ratios averaged 0.99 and 0.95 for calibration (N = 7 years) and verification (N = 5 years) with respective standard deviations of 0.08 and 0.28. 相似文献
693.
ABSTRACT: This paper introduces the application of Computer Intensive Statistics (CIS) to the evaluation of parameter uncertainty with specific reference to the parameters in the ARMA models used in the synthesis of streamflows. The CIS provides an empirically derived joint distribution for all parameters. Random values from this distribution can be drawn for application in the model for the generation of a specific synthetic sample. The CIS originally proposed by Efron and discussed herein is of general applicability in the evaluation of uncertainty in any statistic derived from a set of data. Some comments and limitations of the CIS are discussed in the concluding remarks. 相似文献
694.
695.
Twostepmantis模型是在ASM1模型基础上发展而成,它可对碳氧化、传统硝化反硝化、同时硝化反硝化过程、好氧反硝化进行模拟。应用Twostepmantis模型,对一序批式活性污泥法(SBR)实验进行模拟预测,结果表明,模型确实可以很有效解释大部分实验数据。 相似文献
696.
铁路简支梁桥桥墩横向振动时,可简化为墩顶具有集中质量的悬臂梁模型,地基约束用地基弹簧模拟。研究墩身的结构性损伤时,该模型与基底固结的悬臂梁模型原理相同。利用冲击振动试验法可以准确得到桥墩的一阶振型和一阶频率,利用这两个参数可以构造出一阶振型比、特征参数、一阶曲率模态差三个指标。以一混凝土悬臂梁为例,用一阶振型比、特征参数、一阶曲率模态差指标进行结构损伤识别的数值研究,总结了特征参数指标在结构损伤前后的变化规律。分析结果表明几个指标对损伤比较敏感。 相似文献
697.
本文研究了防化服的设计原则,对我国某型防化服装进行了分析,在腰部、袖型、膝部的结构上进行改进,使服装更趋合理、人性化,更便于作业活动。针对防化服影响防护效果的缝制工艺参数,利用二次通用旋转实验设计,变化机针针号、线迹密度及缝纫线细度三个因素五个水平;针对“三防”面料进行防油、防水、防静电测试,得到防护性能与缝制工艺参数之间的回归方程,并绘出等值曲线图,进一步分析了缝制工艺对面料防油、防水、防静电性能的影响,通过Borda数找出最优缝制工艺参数,并将应用到防化服的加工制作中。 相似文献
698.
Craig A. Stow Kenneth H. Reckhow Song S. Qian Estel Conrad Lamon George B. Arhonditsis Mark E. Borsuk Dongil Seo 《Journal of the American Water Resources Association》2007,43(6):1499-1507
Abstract: The National Research Council recommended Adaptive Total Maximum Daily Load implementation with the recognition that the predictive uncertainty of water quality models can be high. Quantifying predictive uncertainty provides important information for model selection and decision‐making. We review five methods that have been used with water quality models to evaluate model parameter and predictive uncertainty. These methods (1) Regionalized Sensitivity Analysis, (2) Generalized Likelihood Uncertainty Estimation, (3) Bayesian Monte Carlo, (4) Importance Sampling, and (5) Markov Chain Monte Carlo (MCMC) are based on similar concepts; their development over time was facilitated by the increasing availability of fast, cheap computers. Using a Streeter‐Phelps model as an example we show that, applied consistently, these methods give compatible results. Thus, all of these methods can, in principle, provide useful sets of parameter values that can be used to evaluate model predictive uncertainty, though, in practice, some are quickly limited by the “curse of dimensionality” or may have difficulty evaluating irregularly shaped parameter spaces. Adaptive implementation invites model updating, as new data become available reflecting water‐body responses to pollutant load reductions, and a Bayesian approach using MCMC is particularly handy for that task. 相似文献
699.
Hugo A. Loaiciga Miguel A. Mario 《Journal of the American Water Resources Association》1987,23(4):541-554
ABSTRACT: This paper presents criteria for establishing the identification status of the inverse problem for confined aquifer flow. Three linear estimation methods (ordinary least squares, two-stage least squares, and three-stage least squares) and one nonlinear method (maximum likelihood) are used to estimate the matrices of parameters embedded in the partial differential equation characterizing confined flow. Computational experience indicates several advantages of maximum likelihood over the linear methods. 相似文献
700.
Vijay P. Singh Kulwant Singh 《Journal of the American Water Resources Association》1987,23(6):1185-1189
ABSTRACT: The principle of maximum entropy (POME) was used to derive an alternative method for parameter estimation for the three parameter lognormal (TPLN) distribution. Six sets of annual peak discharge data were used to evaluate this method and compare it with the methods of moments and maximum likelihood estimation. 相似文献