Moment and maximum likelihood estimators for Weibull distributions under length- and area-biased sampling

Many of the most popular sampling schemes used in forestry are probability proportional to size methods. These methods are also referred to as size-biased because sampling is actually from a weighted form of the underlying population distribution. Length- and area-biased sampling are special cases of size-biased sampling where the probability weighting comes from a lineal or areal function of the random variable of interest, respectively. Often, interest is in estimating a parametric probability density of the data. In forestry, the Weibull function has been used extensively for such purposes. Estimating equations for method of moments and maximum likelihood for two- and three-parameter Weibull distributions are presented. Fitting is illustrated with an example from an area-biased angle-gauge sample of standing trees in a woodlot. Finally, some specific points concerning the form of the size-biased densities are reported.     

OBSERVATION WELL NETWORK DESIGN FOR PUMPING TESTS IN UNCONFINED AQUIFERS1

ABSTRACT: This paper presents a method for determining locations of observation wells to be used in conducting pumping tests in unconfined aquifers. Sensitivity coefficients, the distribution of relative errors, and the correlation coefficients between four aquifer parameters (horizontal and vertical hydraulic conductivities K_r and K_z, storage coefficient S, and specific yield S_y) are used as the criteria for the design of observation well networks and the interpretation of pumping tests. The contours of the relative errors over a vertical profile are very useful in selecting the “best” location of an observation well. Results from theoretical analyses suggest that a wide range of locations is suitable for the determination of K_r and that good locations for the determination of K_z and S may be poorly suited for the determination of S_y. Consideration must be given to the position and lengths of the pumping well screen in the selection of observation well locations. For a given location, the quality of test data can be improved by using high pumping rates and frequent sampling of drawdowns. We found that a minimum of two and preferably three observation locations are needed along a given transect. Results of the four parameters from a single well analysis may contain higher uncertainties. However, composite analyses of multiple observation wells can reduce the correlation between the four aquifer parameters, particularly between K_r and S_y, thus, improving the quality of parameter estimation. Results from two pumping tests conducted at sites located in Nebraska were examined with regard to the proposed methodology.     

Application of a Modified Health Belief Model to the Pro‐Environmental Behavior of Private Well Water Testing

A social cognition model of health behavior, the health belief model, was applied to the pro‐environmental behavior of private well water testing. Conceptualizing environmental behaviors as health behaviors may provide new insight into pro‐environmental behavior change. A groundwater education program was provided to K‐12 children throughout New England. Both child participants and their parents completed surveys pertaining to private well water behavior. Results indicate that perceived barriers and socioeconomic status significantly influenced past well water testing of parent participants. Perceived barriers included: participants' concern related to the cost of treating their water, and how a well water problem would influence their property value. Parent participants also indicated that they would perform future well water testing if they received a reminder cue to action that might include: getting a discount or reminder in the mail, if a well testing program was available, and state or local requirement. Our findings reinforce the need for continued private well water research and parallels to additional environmental behaviors.     

Picture this: A field experiment of the influence of subtle affective stimuli on employee well‐being and performance

Prior literature examining the antecedents of employee affect has largely ignored subtle affective influences in the workplace and their impact on employees' affective experiences and behaviors. A substantial body of evidence from basic psychology research suggests that individuals' affect can be influenced by minimal stimulus input. The primary objective of this research is to take an initial step towards understanding the “real‐world” impact of subtle affective stimuli in the workplace. Specifically, in a field experiment with a within‐subjects design, we collected data from 68 sales representatives and examined the effect of a subtle affective stimulus (i.e., a black‐and‐white picture of a woman smiling printed on the backdrop of paper–pencil surveys) on employees' affect, well‐being, and performance. Results showed that the smiling picture significantly enhanced participants' positive affect, which in turn influenced employees' extra‐role performance and emotional exhaustion. The smiling picture also indirectly influenced employees' in‐role performance and emotional exhaustion via negative affect. Theoretical and practical implications of these findings are discussed at the end of the paper. Copyright © 2017 John Wiley & Sons, Ltd.     

莱州湾滨海盐渍土中铵态氮水平运移室内模拟试验

莱州湾滨海盐渍土中铵态氮水平运移规律研究表明,铵态氮在水平方向存在运移,运移速率随供试示踪剂源距离的增加而迅速减小,在20cm运移距离内,NH+4由于受到土壤胶体的吸附而逐渐降低,并呈幂函数关系;铵态氮的水平运移主要由土壤对铵吸附的饱和程度决定,而运移速率主要由铵态氮的浓度梯度和水势梯度控制。铵态氮水平运移速率随土壤含水量的增大而升高,并呈指数曲线变化。铵态氮水平运移的浓度受非饱和土壤水扩散率的影响,并随非饱和土壤水扩散率的升高而呈幂函数曲线下降。     

水平井钻磨管柱油管组合方式研究及下入安全性分析

基于钻磨管柱下入过程易造成遇卡事故,油田采用了2种线重油管的组合方式进行钻磨作业,提高了管柱的下入能力,但未能得到2种线重油管组合方式优选的可靠依据。为得到2种线重油管的最优组合方式,采用微元法对管柱单元在各井段的受力进行分析,建立钻磨管柱的下入载荷计算模型;采用编程对油田水平井进行实例计算,计算结果与实测结果对比显示模型平均误差在8.12%左右,验证了模型的正确性;基于下入载荷计算模型,进行了钻磨管柱组合特性研究及参数敏感性分析。结果表明:采用2种线重油管的组合方式能增大钻磨管柱下入能力,当大线重油管所占整个钻磨管柱的长度为井斜角70.8°左右的井深时,组合比例最优,不同的摩擦系数μ决定不同最优组合比例。     

Putting People on the Map through an Approach That Integrates Social Data in Conservation Planning

Conservation planning is integral to strategic and effective operations of conservation organizations. Drawing upon biological sciences, conservation planning has historically made limited use of social data. We offer an approach for integrating data on social well‐being into conservation planning that captures and places into context the spatial patterns and trends in human needs and capacities. This hierarchical approach provides a nested framework for characterizing and mapping data on social well‐being in 5 domains: economic well‐being, health, political empowerment, education, and culture. These 5 domains each have multiple attributes; each attribute may be characterized by one or more indicators. Through existing or novel data that display spatial and temporal heterogeneity in social well‐being, conservation scientists, planners, and decision makers may measure, benchmark, map, and integrate these data within conservation planning processes. Selecting indicators and integrating these data into conservation planning is an iterative, participatory process tailored to the local context and planning goals. Social well‐being data complement biophysical and threat‐oriented social data within conservation planning processes to inform decisions regarding where and how to conserve biodiversity, provide a structure for exploring socioecological relationships, and to foster adaptive management. Building upon existing conservation planning methods and insights from multiple disciplines, this approach to putting people on the map can readily merge with current planning practices to facilitate more rigorous decision making. Poner a la Gente en el Mapa por Medio de una Estrategia que Integra Información Social en la Planeación de la Conservación     

采用分层采样技术对场地地下水污染物进行三维空间描述

地下水单一混合层采样所需建井及采样技术较简单,曾被广泛应用于地下水监测,但根据该技术所得地下水污染物数据进行污染场地地下水污染羽和污染程度描述,常常存在较严重的偏差。以某氯代烃污染场地为例,详细阐述了巢式监测井的建井及分层采样技术,并以该场地主要污染物氯乙烯和氯仿为例,对比了来自不同采样技术的两个主要污染物数据,证实了采用分层采样技术对污染场地地下水进行调查,具有更好的准确性和可靠性。     

新型旋流沉砂池砂粒去除效果的数值模拟

采用MRF模型和DPM模型对新型旋流沉砂池的小试模型进行数值模拟,分析沉砂池内部流场和砂粒运行轨迹、搅拌桨旋转方向以及搅拌桨运动和进水流速关系对砂粒去除效果的影响。结果表明：当搅拌桨旋转运动方向不同时,形成的轴向环流流场有较大差异,其中顺时针旋转有助于砂粒的沉降与去除。当搅拌桨静止时,进水流速对砂粒的沉降有一定影响,其中进水流速较小时池体内会累积较多的砂粒;流速较大时砂粒的逃逸率也随之增大。在进水流速一定时,搅拌桨转速的变化对砂粒的去除有一定的影响,其中转速较小时,形成的涡旋强度不足以将砂粒移向池心;而当转速逐渐增大时,形成的径向流和较强的轴向流将不利于砂粒的沉降与去除。     

Educational,psychosocial, and protection outcomes of child‐ and youth‐focused programming with Somali refugees in Dollo Ado,Ethiopia

Child‐ and youth‐friendly spaces have become a common feature of emergency humanitarian provision. This study reports on the outcomes of child and youth learning centres (CYLCs) in Ethiopia's Buramino Camp established for those fleeing conflict in Somalia. Eighty‐five youths completed baseline assessments shortly after arrival and follow‐up assessments three to six months later. Caregivers of 106 younger children completed similar appraisals. 693 children attending the CYLCs completed pre‐ and post‐educational assessments, which indicated major gains—significant at p<0.0001—in both literacy (younger children, t=9.06; youth, t=13.87) and numeracy (younger children, t=13.94; youths, t=17.10). Children's CYLC attendance increased reports of met needs among caregivers (t=2.53, p<0.05) and youths (t=2.57, p<0.05), and, among caregivers but not youths, significantly moderated protection concerns (t=2.39, p<0.05, and t=?1.90, p=0.06, respectively). There was general improvement in psychosocial well‐being over time for all children; CYLC attendance predicted greater reductions in reported difficulties only among younger children (t=2.51, p<0.05).