EFFICIENTLY REDUCING NONPOINT PHOSPHORUS LOADS TO LAKES AND RESERVOIRS1

ABSTRACT: Several problems that make it difficult to deal with water pollution from cropland are identified. The most immediate need is for a rational framework for determining where conservation programs can make an impact on eutrophication problems in reservoirs draining rural watersheds. This includes estimating the level of control that would be required for each local farm situation and the economic impacts for the planning area. A modeling approach is suggested for a planning area in Southeastern Pennsylvania.     

基于FAD的铝合金车体焊接缺陷安全性评价方法研究

目的确保高速列车运行安全,采用先进的方法和理论对焊接缺陷进行评定显得非常重要。方法采用断裂力学和有限元相结合的方法,建立车体全比例有限元模型。采用热弹塑性法对焊接残余应力进行有限元数值仿真。基于标准BS 7910提供的焊接缺陷评价方法,对焊接缺陷进行安全性评定。结果对车体带焊缝的有限元模型,依据BS EN12663标准施加车体所承受的载荷,获取焊缝关注点的应力转化所得到一次应力。根据关注点信息建立所在焊缝处的接头模型进行热弹塑性仿真模拟,从而获取该关注点残余应力数值及分布转化所得到二次应力。将焊接缺陷进行裂纹当量化,从而计算得到载荷比与应力强度因子比值,结合许用FAD曲线,对高速列车铝合金车体上焊缝关注点进行安全性评价。结论该方法对车体这种大型复杂焊接结构的安全性进行评价是可行的,并对焊接缺陷是否合于使用提出质量控制的建议。     

华中地区畜牧业温室气体排放特征分析与预测

采用IPCC推荐的温室气体清单计算方法,从温室气体排放总量、排放强度等方面分析了华中地区畜牧业温室气体排放现状;根据不同牲畜饲养数量,采用Logisticgrowth model、Gompertzcurve model等非线性时间序列模型模拟2030年华中地区牲畜数量,并计算畜牧业温室气体排放量.结果显示,2015年华中地区温室气体排放为6289.09万t CO₂-eq,单位GDP温室气体排放量为1.13万t CO₂-eq/亿元,单位肉类产量排放强度为3.73t CO₂-eq/t;2030年华中地区畜牧业温室气体排放总量约为4990.06（温室气体排放预测1）~5932.74万tCO₂-eq（温室气体排放预测2）.应当进一步优化畜牧业饲养技术及条件来提高产业温室气体排放效率,科学合理的规划不同牲畜的饲养规模,优化牲畜饲养结构来降低畜牧业温室气体排放量.     

HYDROLOGIC SIMULATION OF THE LITTLE WASHITA RIVER EXPERIMENTAL WATERSHED USING SWAT1

ABSTRACT: Precipitation and streamflow data from three nested subwatersheds within the Little Washita River Experimental Watershed (LWREW) in southwestern Oklahoma were used to evaluate the capabilities of the Soil and Water Assessment Tool (SWAT) to predict streamflow under varying climatic conditions. Eight years of precipitation and streamflow data were used to calibrate parameters in the model, and 15 years of data were used for model validation. SWAT was calibrated on the smallest and largest sub‐watersheds for a wetter than average period of record. The model was then validated on a third subwatershed for a range in climatic conditions that included dry, average, and wet periods. Calibration of the model involved a multistep approach. A preliminary calibration was conducted to estimate model parameters so that measured versus simulated yearly and monthly runoff were in agreement for the respective calibration periods. Model parameters were then fine tuned based on a visual inspection of daily hydrographs and flow frequency curves. Calibration on a daily basis resulted in higher baseflows and lower peak runoff rates than were obtained in the preliminary calibration. Test results show that once the model was calibrated for wet climatic conditions, it did a good job in predicting streamflow responses over wet, average, and dry climatic conditions selected for model validation. Monthly coefficients of efficiencies were 0.65, 0.86, and 0.45 for the dry, average, and wet validation periods, respectively. Results of this investigation indicate that once calibrated, SWAT is capable of providing adequate simulations for hydrologic investigations related to the impact of climate variations on water resources of the LWREW.     

离散型EKC模型与中国“十一五”期间二氧化硫减排目标分析

中国目前已成为二氧化硫排放的第一大国,减排工作受到整个国家乃至全世界的关注。本文以中国政府“十一五”期间二氧化硫减排目标为研究对象,以库兹涅茨的倒“U”型理论为分析基础,研究中国的二氧化硫减排问题。首先,我们通过对影响二氧化硫排放的主要因素进行分析,建立离散型EKC模型,分析中国二氧化硫排放出现转折点的条件;其次,研究了中国政府的“十一五”减排目标,分析“十一五”已过去的前两年,我们所采取的减排力度与减排目标的差距,以及在“十一五”的最后三年,我们面临的减排形势与影响因素。     

荧光定量PCR技术在环境监测中的应用研究

实时荧光定量PCR是在PCR基础上发展起来的一种核酸定量技术,此技术灵敏度高,特异性强。目前也已被国内外应用在环境监测方面。如可以用此方法来监测环境中微生物在河流中随季节的变化情况,评价菌的富集情况,快速检测微生物等。随着此技术的不断发展,此方法在环境监测方面将会有广阔的应用前景。     

一种新的环境与经济评价指数方法的研究

本文针对目前面临的经济发展和环境影响难于定量评价的难题,基于库兹涅茨曲线原理建立了一个对指定样本以经济指标和环境指标为变量的评价指数(库线指数)。并分别将区域、行业或企业设为样本,以其生产总值和污染物排放量为变量,进行了库线指数计算、分析和评价。结果表明该指数能够清晰地说明评价样本经济发展和环境影响的相互关系性质和变化趋势。     

基于Probit-Bayes方法的储罐地震易损性研究

为了研究地震对储罐造成的影响,结合历史上储罐的震害资料,将储罐的损伤程度进行分级,通过采用Bayes方法估计Probit模型参数,再转化成储罐的损伤概率,给出了各个损伤状态下的模型参数及给定地震加速度下储罐的损伤概率,提出了1种基于Probit -Bayes方法估计储罐易损性的计算方法。结果表明:所提出的地震损伤计算方法,能够有效的评估储罐在不同地震加速度下的损伤程度,可为震后储罐的安全评估提供理论依据。     

Using and comparing two nonparametric methods (CART and MARS) to model the potential distribution of gullies

Gully erosion represents an important soil degradation process in rangelands. In order to take preventive or control measures and to reduce its environmental damages and economical costs it is useful to localize the points in the landscape where gullying takes place and to determine the importance of the different factors involved. The study is carried out in Extremadura, southwest Spain. The main objectives of this work are: (a) comparing two nonparametric schemes to model the potential distribution of gullies, (b) evaluating the importance of the different factors involved in gullying processes, (c) analyzing the role of prevalence in the success of the model and finally, (d) implementing and mapping the results with the help of a Geographical Information System (GIS). Two methods were used to model the response of a dependent variable (gullying) from a set of independent variables: Classification And Regression Trees (CART) and Multivariate Adaptive Regression Splines (MARS). Three different datasets were used; the first one for constructing the model (training dataset) and the others for validating the model (external datasets). These datasets are formed by a target variable (presence or absence of gullies) and a set of independent variables. The dependent variable was obtained by mapping the locations of gullies with the help of a GPS and high resolution aerial ortophotographs. A set of 32 independent variables reflecting topography, lithology, soil type, climate, land use and vegetation cover of each area were used. The performance of the models was evaluated using a non-dependent threshold method: the Receiver Operating Characteristic (ROC) curve. The results showed a better performance of MARS for predicting gullying with areas under the ROC curve of 0.98 and 0.97 for the validation datasets, while CART presented values of 0.96 and 0.66.     

非等距饱和指数曲线参数的灰色辨识及其应用

根据非等距ＧＭ（１,１）的建模原理,建立了非等距和指数曲线参数灰色辨识的二次一元线性回归解法。初步应用表明,本法计算简便,信息利用率高,拟合精度好,不仅为饱和指娄曲线参数辨识提供了新途径,也进一步拓广了它的应用范围。