冻融循环作用下岩桥变形破裂及能量转化特征研究*

为研究寒区锁固型岩质边坡的破坏机制,对岩桥试件开展冻融循环试验和单轴压缩试验。以数字图像相关方法为观测手段获得加载过程中的全局应变场,分析冻融循环作用对岩桥变形破裂演化特征的影响。引入能量特征指标,探究冻融岩桥加载过程中的能量耗散和释放规律。研究结果表明:随着冻融循环次数的增加,试件抗压强度和弹性模量逐渐劣化;冻融循环作用未改变最终破坏模式,均表现为剪切裂纹贯穿中部岩桥造成的失稳破坏。冻融循环作用促进应变集中带的出现和扩展,加剧裂隙周边的应变集中程度。随着冻融循环次数的增加,试件储能极限和应变能峰后转化率逐渐降低,说明冻融循环作用减缓能量耗散和释放;试件最终破坏与能量转化密切相关,储能极限和应变能峰后转化率越大,试件脆性破坏越显著。     

Hydro-chemical Survey of Groundwater of Hisar City and Assessment of Defluoridation Methods Used in India

Ground water quality of Hisar city was assessed for its suitability for drinking purposes. Samples collected from the Bore-wells (forms a part of municipal water supply) and handpumps (direct consumption) were analyzed for the various physico-chemical parameters including pH, electrical conductivity, total dissolved salts, total hardness, total alkalinity, sodium, potassium, calcium, magnesium, carbonate, bicarbonate, chloride and sulfate. The concentrations of magnesium, sodium, potassium, sulfate and especially of chloride were found moderately higher than the WHO standards for the drinking water. Further a comparison of fluoride (F⁻) levels in groundwater of various cities and towns of Haryana state was performed. The relatively higher concentrations of F⁻ in groundwater of Haryana raise the risk of fluorosis and hence groundwater must be used with proper treatment. Promising defluoridation methods using locally available materials and technologies are discussed for the prevention and control of fluorosis. Data were assessed statistically to find the suitable markers of ground water quality as an aid to monitoring groundwater quality.     

养分(磷)吸收机理模型的应用研究──Ⅱ.模型参数的敏感性分析

采用Claassen的养分吸收机理模型探讨了玉米与大豆幼苗磷吸收过程中的参数敏感性,结果表明：在一般土壤与施肥条件下,玉米与大豆幼苗吸收磷的高度敏感性参数或重要限制因素为根系伸长速率与根半径;在相同土壤供磷条件下,供试大豆幼苗根系的磷摄取能力远低于玉米幼苗根系的磷摄取能力,其原因归结于两者在根系最大养分流Imax与根系伸长速率K两个敏感性参数上的差异;玉米与大豆幼苗磷吸收过程中三种根毛参数的敏感性均较低,这主要与土壤供磷水平较高有关;土壤含水量在玉米幼苗磷吸收过程中表现了极高的敏感性,当土壤含水量降低时,土壤养分供应参数对玉米幼苗磷吸收的敏感性与限制作用均增大。     

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.     

Heterogeneity of farmers' preferences towards agri-environmental schemes across different agricultural subsystems

Specialised literature on the uptake of agri-environmental schemes (AES) has paid little attention to how this can be influenced by the different types of agricultural systems. This paper analyses the heterogeneity of farmers' preferences towards these schemes, distinguishing between different subsystems within the same agricultural system. We use the choice experiment method to analyse the case study of three olive grove subsystems in southern Spain, with the subsystems ranging from extensive to intensive. The results reveal inter- and intra-subsystem heterogeneity of farmers' preferences towards AES, both in general and specifically related to scheme attributes. A variety of factors appear to lie behind inter-subsystem heterogeneity, especially those associated with subsystem specificities (principally, the type of joint production). Likewise, numerous factors play a role in intra-subsystem heterogeneity, most of them related to farm/farmer socio-economic and physical characteristics. These findings will help in the design of more efficient AES.     

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。     

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.     

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。     

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.     

稻壳基活性炭的制备及其对亚甲基蓝吸附的研究

以稻壳为原料,采用K2CO3活化法和H3P04活化法制备了比表面积为1312m^2／g和682m^2／g的活性炭,通过扫描电子显微镜（SEM）、X-射线衍射仪（XRD）对样品进行了表征,并将孔隙发达的活性炭样品用于对亚甲基蓝的吸附,结果表明,K2CO3活化法制备的活性炭样品具有更多的微孔结构;随着亚甲基蓝溶液初始浓度的增加、活性炭吸附时间的延长,亚甲基蓝的去除率呈现逐渐降低和逐渐增大的变化规律,当pH值为6时,活性炭对亚甲基蓝的吸附效果最佳;稻壳基活性炭对亚甲基蓝的吸附等温线符合Langmuir模型,Qm最高可达476．2mg／g;热力学参数△G^0△H^0和△S^0均为负值,表明稻壳基活性炭对亚甲基蓝的吸附是一个自发的放热反应。