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冬小麦种植面积空间抽样单元尺寸优化设计 总被引:5,自引:5,他引:5
抽样单元尺寸是空间抽样调查方案设计过程中的关键要素。合理的抽样单元尺寸对降低抽样调查费用、改善抽样外推总体精度具有重要意义。为实现农作物种植面积空间抽样调查中抽样单元尺寸的优化设计,论文以河南省为研究区,以冬小麦种植面积为研究对象,选取正方形网格作为抽样单元,遵循传统抽样理论中抽样单元间相互独立原则,通过分析不同抽样单元尺寸与对应该尺寸下的抽样框内总体单元间全局空间自相关指数(Moran’s I)的相关关系,进行了抽样单元尺寸的初选。为最终实现抽样单元尺寸优选,基于初选的8种抽样单元尺寸,分别构建抽样框,采用以抽样单元内冬小麦面积占单元面积比例(麦土比)为分层标志的分层抽样方法进行了研究区冬小麦种植面积空间抽样样本抽选、总体外推及误差估计试验研究,结果表明:抽样比随抽样单元尺寸的增大而增大;8种抽样单元尺寸下的外推总体相对误差和变异系数均较小,变化范围分别为3.82%~5.75%和3.76%~4.69%;以抽样调查费用和抽样误差为抽样效率评价指标,优选出抽样单元尺寸为20 000 m×20 000 m时,进行研究区冬小麦种植面积抽样调查的效率最高。 相似文献
313.
Spatial distribution of soil heavy metal pollution estimated by different interpolation methods: accuracy and uncertainty analysis 总被引:15,自引:0,他引:15
Mapping the spatial distribution of contaminants in soils is the basis of pollution evaluation and risk control. Interpolation methods are extensively applied in the mapping processes to estimate the heavy metal concentrations at unsampled sites. The performances of interpolation methods (inverse distance weighting, local polynomial, ordinary kriging and radial basis functions) were assessed and compared using the root mean square error for cross validation. The results indicated that all interpolation methods provided a high prediction accuracy of the mean concentration of soil heavy metals. However, the classic method based on percentages of polluted samples, gave a pollution area 23.54-41.92% larger than that estimated by interpolation methods. The difference in contaminated area estimation among the four methods reached 6.14%. According to the interpolation results, the spatial uncertainty of polluted areas was mainly located in three types of region: (a) the local maxima concentration region surrounded by low concentration (clean) sites, (b) the local minima concentration region surrounded with highly polluted samples; and (c) the boundaries of the contaminated areas. 相似文献
314.
315.
Daniel B. Abrams Cecilia Cullen Fereshteh Ghiami Shomami 《Journal of the American Water Resources Association》2023,59(3):481-497
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. 相似文献
316.
Mehdi Ghasemi Jebrail Nasleseraji Sedigheh Hoseinabadi Mohsen Zare 《International journal of occupational safety and ergonomics》2013,19(2):203-209
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. 相似文献
317.
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。 相似文献
318.
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 相似文献
319.
Dupré Mickaël 《Waste management (New York, N.Y.)》2014,34(4):730-737
Household waste management has become essential in industrialized countries. For the recycling programs to be a success, all citizens must comply with the developed residential procedures. Governmental bodies are thus dependent on as many people as possible adhering to the sorting systems they develop. Since the 1970s oil crisis, governments have called upon social psychologists to help develop effective communication strategies. These studies have been based on persuasion and behavioral commitment (Kiesler, 1971). Less common are studies based on developing participative communication (Horsley, 1977), a form of communication that relies on individuals to pass on information. After going through the main communication perspectives as they relate to the sorting of household waste, a comparative field study will be presented on the effectiveness of persuasive, committing and participative communication. Participative communication relied on users to pass along information to their neighbors. The results show that the participants who spread information in this way, along with those who made a commitment, changed their behavior to a greater degree than the other participants. 相似文献
320.