Assessing Parameter Uncertainty of a Semi‐Distributed Hydrology Model for a Shallow Aquifer Dominated Environmental System

This paper examines the performance of a semi‐distributed hydrology model (i.e., Soil and Water Assessment Tool [SWAT]) using Sequential Uncertainty FItting (SUFI‐2), generalized likelihood uncertainty estimation (GLUE), parameter solution (ParaSol), and particle swarm optimization (PSO). We applied SWAT to the Waccamaw watershed, a shallow aquifer dominated Coastal Plain watershed in the Southeastern United States (U.S.). The model was calibrated (2003‐2005) and validated (2006‐2007) at two U.S. Geological Survey gaging stations, using significant parameters related to surface hydrology, hydrogeology, hydraulics, and physical properties. SWAT performed best during intervals with wet and normal antecedent conditions with varying sensitivity to effluent channel shape and characteristics. In addition, the calibration of all algorithms depended mostly on Manning's n‐value for the tributary channels as the surface friction resistance factor to generate runoff. SUFI‐2 and PSO simulated the same relative probability distribution tails to those observed at an upstream outlet, while all methods (except ParaSol) exhibited longer tails at a downstream outlet. The ParaSol model exhibited large skewness suggesting a global search algorithm was less capable of characterizing parameter uncertainty. Our findings provide insights regarding parameter sensitivity and uncertainty as well as modeling diagnostic analysis that can improve hydrologic theory and prediction in complex watersheds. Editor's note : This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.     

硝基苯甲酸结构对其在EPDM膜中萃取效果的影响

以3种取代基位置不同的硝基苯甲酸为研究对象,研究了辛醇/水分配系数、溶解度、摩尔体积、分子极化率和偶极矩5种结构参数对硝基苯甲酸在三元乙丙橡胶（EPDM）膜中萃取效果的影响。实验结果表明：EPDM膜对硝基苯甲酸有一定的去除效果,邻、间、对硝基苯甲酸的去除率分别为27.1%、32.4%和41.6%;取代基位置的不同使硝基苯甲酸的去除效果出现差异,其疏水性越强越易在EPDM膜中溶解和渗透;硝基苯甲酸的去除率和透过率与其辛醇/水分配系数和分子极化率正相关,与溶解度负相关;硝基苯甲酸的去除率可用分子极化率和偶极矩两个结构参数进行预测。     

活性污泥模型参数结构可识别性研究方法进展

参数估计是活性污泥模型应用的前提,可识别性研究是参数估计的第一步。本文以异养菌生长模型为例,论述了目前适用于活性污泥模型参数结构可识别性研究的几种方法,可以看出这些方法都存在着某些缺陷,因此寻求两种或多种方法的耦合方法成为以后理论研究的方向。     

基于均匀实验设计的曝气池柔性设计方法

为了解决污水处理过程由于水质水量等不确定性参数偏离设计值所引发的问题,提出了一种基于均匀实验设计的曝气池柔性设计方法。该方法用均匀设计产生不确定性参数区域内具有代表性的不确定性情形,用因子设计生成应对这些情形的操作方案,在柔性瓶颈处通过直观分析寻找改进设计方案的策略。从案例研究可以看出,传统的没有系统化地考虑不确定性参数变化的设计方法,所设计的曝气池在一些不确定性情形下,可能无法正常运行,而本方法有助于避免这一缺陷。     

Quantized control settings based tuning of a heaving wave energy converter in irregular seas

The increasing awareness of environmental issues attracts more attention on environmentally friendly energy sources. This leads to increasing research on effective use of renewable energy sources. Among them, wave energy offers a high potential. The wave energy converter systems used for transforming the wave energy into electrical energy have been a main research topic for decades. However, only a few of these systems has been successfully implemented. There seems to be some technical problems one of which is on their control applications. It has been reported that by means of appropriate control implementation, the performance of the wave energy converter system could be improved considerably. In literature, many different control techniques are reported. They appear to be weak due to implementation related restrictions. The present study proposes a novel control technique that is far more practical based on quantization of control settings. Various quantization levels and their effect on system power capture performance are studied. The technique assumes use of realistic off-the-shelf components with realistic features. The proposed method utilizes time-series-analysis technique with online parameter estimation feature. This new method does not require any knowledge of previous or future states of any of the system or sea state parameters, but only the currently available and measurable ones. The approach of the new control technique sets it apart from most of the previously reported ones. Therefore, the proposed technique is not only very much practical but also very much useful in improvement of the system power performance relative to passive techniques.     

两种不同方式培养硝化细菌的比较研究

在全自养(不投加有机碳源)与保持COD∶N=1.7∶1.0(质量比)条件下,研究了硝化细菌的培养生长规律。结果表明,两种培养方式下,硝化率均能达到99%以上,但发展趋势有所不同。全自养时,培养末期亚硝酸盐细菌和硝酸盐细菌个数分别达到了2.5×106、4.5×104 cfu/mL,COD∶N=1.7∶1.0时分别为2.0×106、7.5×104 cfu/mL,处于同一数量级上。扫描电镜(SEM)观察则表明,两种培养方式下微生物均以杆菌和球菌为主,与硝化细菌的特征相符。然而碳源的单一性会使全自养条件下污泥浓度逐渐减小,而保持一定碳氮比时则使污泥浓度逐渐增加,有助于维持系统的稳定。     

Residents' willingness to pay for improved liquid waste treatment in urban Ethiopia: results of choice experiment in Addis Ababa

This paper discusses residents’ willingness to pay (WTP) for improved liquid waste treatment in Addis Ababa based on data collected in 2011 using random parameter logit model. Findings indicate that respondents are willing to contribute for improved liquid waste treatment with higher quantity and quality. Their mean WTP for the medium improvement scenario is found to be 15.53 ETB (0.93 USD) per month. The compensation surplus tends to increase from the status quo to the alternative scenarios with aggressive improvement. Finally, the paper concludes by indicating the socioeconomic difference across households, and sub-cities need to be considered in designing environmental protection plans for the city.     

基于Hilbert-Huang变换理论的结构损伤检测

详细介绍了一种适合分析非线性非平稳数据的新方法——Hilbert-Huang变换,并将此方法应用于结构损伤检测。仿真实验是某三层剪切型建筑结构受两种不同地震烈度的地震动激励,结构在此过程中出现的损伤由层间刚度衰减的方法近似模拟,用巴特沃斯低通滤波器对得到的每层加速度数据进行滤波,然后对滤波后的数据进行Hilbert-Huang变换分析,得到其Hilbert谱,并对Hilbert谱进行了分析。结果表明,此方法能有效地提取结构的损伤特征,从而对结构的健康状况做出诊断。     

地下水与优势结构面对库岸滑坡形成的联合效应——以龙羊峡近坝库岸滑坡为例

为了深入研究近坝库岸滑坡的形成机理,首先分析了区域地下水的溶蚀作用和动水压力作用,又运用综合评分法确定出了对滑坡形成有利的优势结构面,发现区域滑坡滑带的形成是地下水与优势结构面长期联合作用的结果。以龙羊峡滑坡为例,揭示了半成岩湖相地层中滑坡滑带独特的三段式结构特征,验证了地下水与优势结构面的联合效应对近坝库岸滑坡形成的控制作用。     

用雨流计数法统计地震波的动力循环参数

引入雨流计数法统计地震波的动力循环参数。采用雨流计数法不仅可以统计地震动的振动幅度分布,而且可对地震波的动力循环的加载速度、加载顺序进行统计,也可为评估震后结构的损伤、砂土振动液化判别等与动力循环性质有关的研究提供必需载荷基础数据的一种新方法。