What is a static head measurement? Evaluating structural error and implications for regional groundwater modeling

Most groundwater modelers avoid using static heads measured from active production wells because they can introduce a bias into model calibration. However, in the deep confined Cambrian-Ordovician Sandstone Aquifer System in the Central Midcontinent of North America, dedicated observation wells are sparse and remote from areas of most concentrated pumping. As a result, in areas where drawdown is the greatest and modeling is most needed, only static heads from production wells are available for calibration. This paper evaluates two leading sources of discrepancies in using production well data, spatial and temporal structural error (S.E.). A simple Theis solution is used to evaluate the potential magnitude of spatial S.E. when calibrating a regional MODFLOW model with coarse cell resolution. Despite theoretical analyses indicating that spatial S.E. could be significant, statistical analysis of the model results suggests that temporal S.E. is dominant. Long (ranging over decades) or frequent (monthly) head datasets are key in understanding temporal S.E., to better capture water-level variability. In this study, the range in static head observations impacted estimates of the remaining time a well could extract water from the aquifer by 0.1 to 16.0 years. This uncertainty in future water supply is highly relevant to stakeholders and must be assessed in hydrographs depicting risk.     

Application of SHERPA to Identify and Prevent Human Errors in Control Units of Petrochemical Industry

Introduction. Studying human errors as a risk factor in the occurrence of accidents is necessary. Thus, the aim of this study was to identify, predict and control human errors in industrial control units. Method. This is a case study carried out using SHERPA in the first unit of Zagros Methanol of Asalooyeh, Iran, and its subunits. To collect the required data, various methods were used: observing, interviewing processing specialists and control unit operators, and studying technical documents and records. Results. In total, 222 human errors were identified in various occupational tasks. This study showed that 48.62% of them were action errors, 31.97% were checking errors, 6.75% were retrieval errors, 11.70% were communication errors and 0.90% were selection errors. Conclusion. It can be inferred that this method is appropriate for different industries, and it is useful for identifying human errors leading to hazardous accidents.     

U-series disequilibria in a groundwater flow route as an indicator of uranium migration processes

U-series data relating to groundwater, fracture coatings and the adjoining rock matrix in a groundwater flow system at the Palmottu natural analogue site was examined. The aim was to obtain an experimental reference for migration modelling in a transport section defined within the flow system. The U-series reference obtained turned out to be a very useful tool for fine tuning the flow route and for migration mechanism considerations. The U-series data are well in line with other interpretations of the migration system.     

降水产流同位素径流分割研究进展与展望

降水产流是陆地水循环中大气降水补给地表水的重要环节。氢氧稳定同位素的指纹效应能够有效示踪径流的补给来源、路径和地理区域。同位素径流分割模型已从二元分割逐渐发展到三元乃至多元分割模型,多学科交叉也逐渐丰富了径流分割研究的方法体系。本文对同位素径流分割在降水产流中的应用进展作了总结分析,介绍了环境同位素（²H和¹⁸O）在降水产流研究中的应用现状、存在的不确定性以及处理误差的方法和应用特点。最后对环境同位素在径流分割领域的应用前景进行了论述,提出环境同位素结合GIS、InSAR、ERT等地球物理方法,将进一步深化流域水文要素时空变化的研究。     

Determining Decision Thresholds and Evaluating Indicators when Conservation Status is Measured as a Continuum

Categorization of the status of populations, species, and ecosystems underpins most conservation activities. Status is often based on how a system's current indicator value (e.g., change in abundance) relates to some threshold of conservation concern. Receiver operating characteristic (ROC) curves can be used to quantify the statistical reliability of indicators of conservation status and evaluate trade‐offs between correct (true positive) and incorrect (false positive) classifications across a range of decision thresholds. However, ROC curves assume a discrete, binary relationship between an indicator and the conservation status it is meant to track, which is a simplification of the more realistic continuum of conservation status, and may limit the applicability of ROC curves in conservation science. We describe a modified ROC curve that treats conservation status as a continuum rather than a discrete state. We explored the influence of this continuum and typical sources of variation in abundance that can lead to classification errors (i.e., random variation and measurement error) on the true and false positive rates corresponding to varying decision thresholds and the reliability of change in abundance as an indicator of conservation status, respectively. We applied our modified ROC approach to an indicator of endangerment in Pacific salmon (Oncorhynchus nerka) (i.e., percent decline in geometric mean abundance) and an indicator of marine ecosystem structure and function (i.e., detritivore biomass). Failure to treat conservation status as a continuum when choosing thresholds for indicators resulted in the misidentification of trade‐offs between true and false positive rates and the overestimation of an indicator's reliability. We argue for treating conservation status as a continuum when ROC curves are used to evaluate decision thresholds in indicators for the assessment of conservation status. Determinación de Umbrales de Decisiones y Evaluación delos Indicadores cuando se Mide el Estado de de Conservación como un Continuo     

距离相关分析法在航空维修人为差错分析中的应用

目的为有效预防人为差错,制定相应可靠的预防机制和措施提供科学依据。方法将距离相关分析法应用到航空维修人为差错综合分析中,计算出航空维修人为差错相关系数,对各个影响因素进行数学化表达。结合距离相关分析理论,对相关系数进行定性分析。结果该方法切实可行,分析结果易于理解,影响航空维修人为差错的各个因素之间有着密不可分的联系。因组织管理与因业务技能因素导致的人为差错的相关系数为0.983。结论制定预防航空维修人为差错的措施时,应将各个因素进行综合考量。     

城市路面径流污染负荷及采样次数对其估算准确性的影响

在西安市城市主干道南二环路建立路面径流原位采样站,利用自制流量等比例采样装置,采集2009年3月-2010年2月的36场降雨径流,测试各场次径流SS、COD、溶解性COD、NH4-N、Pb、Zn和溶解态Pb、Zn的事件平均浓度(EMC),计算径流年污染负荷,并采用随机抽样方法研究采样次数对污染负荷估算准确性的影响.结果...     

Implementing an effective conduct of operations and operational discipline program

This paper introduces the concepts of conduct of operations (COO) and operational discipline (OD), the attributes of effective COO/OD systems, and the steps an organization might take to improve its COO/OD programs. In general, the COO program encompasses the management systems developed to encourage performance of all tasks in a consistent, appropriate manner. OD is the deliberate and structured execution of the COO management systems by personnel throughout the organization. By introducing a framework and tools for describing, evaluating, and improving COO/OD, this paper provides guidance that can be used by companies to improve process safety performance.     

CREAM-based communication error analysis method (CEAM) for nuclear power plant operators’ communication

Communication error has been considered a primary cause of many incidents and accidents in the nuclear industry. In order to prevent these accidents, a method for the analysis of such communication errors is proposed here. This paper presents a qualitative and a quantitative method to analyze communication errors. The qualitative method focuses on finding a root cause of the communication error and predicting the type of communication error which could happen in nuclear power plants. We develop context conditions and antecedent-consequent links of influential factors related to communication errors. The quantitative analysis method focuses on estimating the probability of communication errors. To accomplish the quantification of communication errors, the Cognitive Speaking Process (CSP) is defined and a method to estimate the weighting factors and the probability is suggested. Finally, case studies conducted to validate the applicability of the proposed methods are detailed. From the results, we can foresee the effects of given plant conditions on communication errors and reduce the error occurrences.