Empirical Bayes calculations of concordance between endpoints in environmental toxicity experiments

Hierarchical models are considered for estimating the probability of agreement between two outcomes or endpoints from an environmental toxicity experiment. Emphasis is placed on generalized regression models, under which the prior mean is related to a linear combination of explanatory variables via a monotone function. This function defines the scale over which the systematic effects are modelled as additive. Specific illustration is provided for the logistic link function. The hierarchical model employs a conjugate beta prior that leads to parametric empirical Bayes estimators of the individual agreement parameters. An example from environmental carcinogenesis illustrates the methods, with motivation derived from estimation of the concordance between two species carcinogenicity outcomes. Based on a large database of carcinogenicity studies, the inter-species concordance is seen to be reasonably informative, i.e. in the range 67–84%. Stratification into pertinent potency-related sub-groups via the logistic model is seen to improve concordance estimation: for environmental stimuli at the extremes of the potency spectrum, concordance can reach well above 90%.     

应用蝶啶荧光分析法推断巨尾阿丽蝇成虫日龄

为探明蝶啶荧光分析法在尸食性蝇类成虫日龄推断中的应用潜力,采用荧光分光光度计对4种恒温和自然变温下巨尾阿丽蝇(Aldrichina grahami)雌雄成虫头壳蝶啶含量与日龄的关系进行了研究.结果表明,性别、温度和日龄对成虫蝶啶含量均有显著影响,其中日龄为最主要的影响因子.在16℃、20℃、24℃和28℃下,雌雄成虫头壳蝶啶含量与日龄均呈显著的线性关系(P<0.01,R2>0.90).蝶啶积累速率与温度也呈显著的线性关系.应用蝶啶荧光分析法对自然变温下巨尾阿丽蝇雌雄成虫日龄的估计表明,估计日龄与实际日龄呈显著的线性关系,其中雌成虫日龄估计误差平均为2.68d,雄成虫为±1.56d.以上研究结果表明,蝶啶荧光分析法在巨尾阿丽蝇成虫尤其是雄成虫日龄的推断中具有较大的应用价值.图4表2参19     

基于CRITIC-有限区间云模型的边坡稳定性评价

针对岩质边坡危险性分级的不确定性,选取坡高、坡角岩体结构特征、岩石单轴抗压强度等12项定量评价指标构建评价体系。根据有限区间云模型的相关概念和计算模型,求出露天采场边坡实测数据的云模型特征参数,利用正向云发生器生成云滴图进行量性概念的转化,通过改进的CRITIC法确定指标权重,进而求出不同采场隶属于不同危险等级的综合隶属度,实现边坡稳定性等级的划分。研究结果表明:评价结果与实际相符,利用CRITIC算法求取的权重值,可以考虑各评价指标的综合信息量以及指标间的相关性系数,使评判结果更具有准确性;同时可以快速准确判断出边坡稳定性分级,进行安全预测,为评价边坡的稳定性提供了新思路。     

基于区间概率优势决策模型的滑坡治理方案优选研究

滑坡灾害治理初步设计阶段的方案优选和科学处置,对于避免或减少生命财产损失具有重要的科学和工程意义。针对滑坡治理决策指标信息属性的复杂性、区间性与不确定性等特征,首先借鉴博弈决策论的Minimax算法优化思路,结合概率优势关系及粗糙集相关理论,提出滑坡灾害治理方案优选的区间概率优势关系决策模型,该模型考虑治理方案与理想方案之间的优势度及其属性值的概率测度,与方案属性值大小之间存在着等价关系;然后利用属性值优势关系求得权重量化值,同时基于离差最大化算法和推论2对治理方案进行排序和反演;最后通过工程案例仿真模拟进行验证。研究结果表明:优选方案可为滑坡工程项目治理提供借鉴和参考。     

基于区间直觉模糊信息TODM法的水利工程应急决策研究

为更合理地进行应急方案比选,减少不确定因素和决策者偏好对决策结果的影响,构造了1种更加适应水利工程应急决策的模型。针对应急决策环境的模糊性和不确定性,引入区间直觉模糊集表达评价信息,采用区间直觉模糊熵计算各指标权重;通过构造备选方案两两比较矩阵,运用区间直觉模糊距离测度公式计算方案间的损益值;结合TODIM法计算各方案相对占优度并进行比较排序,确定最优方案。研究结果表明:在损失规避系数确定的前提下,选择任一区间直觉模糊距离公式都不影响方案的优劣排序,决策模型具有一定的可靠性和稳定性。     

中小城市空气环境指标的多角度分析研究——以楚雄市为例

文章根据楚雄市空气污染数据,采用统计的方法从不同的角度探求中小城市空气污染指标的变化规律,并求出三种污染物的同时置信区间及它们之间的关联性。结果表明:楚雄市的空气污染主要由SO2造成,室外空气质量能达到一类地区的水平,三种污染物之间两两相关性较弱,但整体相关性较强,同时根据结论提出了相应的建议。     

A Jackknife Approach to Examine Uncertainty and Temporal Change in the Spatial Correlation of a VOC Plume

The application of geostatistics to spatial interpolation of time-invariant properties in ground-water studies (such as transmissivity or aquifer thickness) is well documented. The use of geostatistics on time-variant conditions such as ground-water quality is also becoming more commonplace. Unfortunately, the detection of temporal changes in spatial correlation through direct comparison of experimental semivariograms is difficult due to the uncertainty in sample semivariograms constructed from field data. This paper discusses the use of the jackknife approach to estimate confidence limits of semivariograms of trichloroethane (TC) and other volatile organic compounds (VOC) in contaminated ground-water in northern Illinois. Examination of the spread of the confidence limits about the semivariograms created from two types of sampling networks are discussed.     

湿式文丘里除尘工艺改进的应用研究

通过对湖北田力实业股份有限公司麻石(文丘里)水膜除尘工艺在沸腾炉烟气除尘中存在的问题进行研究和分析,对(文丘里)水膜除尘工艺进行了改进。采用加装U型布水装置和采取间歇性用水冲刷灰垢的措施,解决了烟道内壁水、气界面处的结垢问题,替换了人工除垢,且烟尘排放浓度达到了环保要求,其回收的烟尘通过外销又取得了经济效益。     

基于Copula模型的降雨量与土壤饱和度的模拟研究

采用两步法,针对云南东川蒋家沟流域的降雨量与土壤饱和度,建立了边缘为皮尔逊Ⅲ型的Clayton Copula模型,分析了降雨量和土壤饱和度之间相关结构,以及两变量重现期,模拟了流域内土壤饱和度的变化情况。实例表明所构造的Clayton Copula模型能比较好地模拟出流域内土壤饱和度在降雨情况下逐日变化情况,有助于进一步认识降水对土壤饱和度的作用过程,并为分析泥石流灾害的发生提供了一种新思路。