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331.
Giuseppe Arbia Daniel A. Griffith Robert P. Haining 《Environmental and Ecological Statistics》2003,10(3):375-396
The collection of accurate and timely information on land use, crops, forest and vegetation are increasingly based on remote sensing spectral measurements produced by satellites. The most recent spacecrafts like the Earth Observing 1 (EO-1) produce a rich source of information being endowed with hyperspectral sensors that can provide up to 200 or more channels. In many instances such a multivariate signal has to be reduced to just one single value per pixel representing a particular characteristic of land. Linear combinations of bands are the general form of many indices. Since each individual image used to construct indices contains errors, when combined they produce a propagation of errors, a process that can distort a final output map. In this paper we measure the extent of error propagation when building linear vegetation indices. We consider three types of indices: the difference vegetation index (DVI), selected Kauth-Thomas indices (SBI, GVI and WET), and principal components, using benchmarking examples taken from the remote sensing literature. The main implication emerging from these examples is that the SBI and the first principal component are the indices more prone to error propagation. The formalization presented here allows a user to derive measures of error propagation in cases where technical characteristics of a sensor and physical characteristics of a landscape are known. These results can help a user to choose between alternative vegetation indices, and to associate a measure of reliability with such indices. 相似文献
332.
以家用微波炉,全聚四氟乙烯微波消化罐和HNO3/H2O2消解体系溶样,选择最佳溶样条件,对发样和标准物质进行测定,并和传统湿法(HNO3/HCLO4)消解体系溶样做了对比,通过测定和比较,表明微波溶样具有较好的精密度和准确度,证明这一方法是可行的。 相似文献
333.
1.Information on all maps, including those which depict characters of the natural environment, is subject to locational error. 2.Locational errors on field-sketched maps are attributable to inaccuracies both in the base map itself and in the method of locating and recording features onto the base map. 3.Two main sources of error associated with field sketch mapping were quantified using the River Corridor Survey maps as an example. First, channel widths are routinely exaggerated on these maps to allow recording of in-channel features. Distortions of river bank length of the order of 25% were shown to arise from a four-fold exaggeration of the width of a sinuous channel. Second, discrepancies in feature location of the order of 20% were found along a 500 m river stretch, although errors could be reduced to approximately 2% if undistorted, large-scale base maps were used. 4.An abundance scale appropriate to the inherent locational inaccuracy was devised to extract semi-quantitative information from River Corridor Surveys recorded on distorted base maps. Application of this scale to 29 River Corridor Survey maps of a 14·5 km river corridor produced a useful representation of environmental gradients within the corridor. 5.With the increasing potential to integrate and analyse environmental information within large computer databases including Geographic Information Systems, it is essential that the level of accuracy is recognised and quantified so that the errors can be allowed for in the development of methods of extracting information from the maps. 相似文献
334.
双样图可应用于实验室分析质量考核中,除了判断测定数据的质量外,也可以利用双样图来分析不同实验室或同一实验室不同分析人员测定数据误差大小及主要来源。应用双样图具有速度快、方便、效果好的特点,避免了实验室工作质量控制考核中,仅凭双样的保证值判断数据合格与否的单一性和不完全性。 相似文献
335.
人的失误本质及检测的研究 总被引:2,自引:0,他引:2
对人的失误本质、定义及特点作了系统的分析研究。针对人的失误产生条件、原因及类型,提出了检测失误与控制失误的技术 相似文献
336.
This article investigates a laboratory incident that occurred during the analysis of a thermal runaway reaction of acrylonitrile monomer. This failure, which was attributed to an human error, resulted in financial losses and corresponding unexpected results. The incident not only damaged the interior of the vessel and other instrument parts, but also exposed the researchers to considerable danger, necessitating their escape from the laboratory. The failure characteristics are discussed, and countermeasures are developed to prevent such a type of incident from reoccurring. 相似文献
337.
第二代人的可靠性分析方法的进展 总被引:8,自引:2,他引:6
在探讨第一代人的可靠性分析 (HRA)方法的局限性之后 ,笔者进而探讨第二代HRA方法的模型 ,建立在多种学科 (认知心理学、行为科学、可靠性工程等 )相互结合的基础上 ,又着重研究产生人的行为 /绩效的情景环境以及它们是如何影响人的行为 /动作的 ,并与工业系统的运行经验和现场或模拟机获得的信息紧密结合。重点介绍了以“失误分析技术”(ATHEANA)和“认知可靠性和失误分析方法”(CREAM)为代表的第二代HRA方法。它们是当前HRA领域中的具有应用和发展前景的新框架思想。 相似文献
338.
339.
为考核CCAR141飞行学校多人制机组驾驶员执照(Multi-crew Pilot License,MPL)训练效果,对其核心单元——威胁与差错管理(Threat and Error Management,TEM)能力进行评估.在分析ANP原理和模糊综合评价方法的基础上,结合ICAO的PANS-TRG文件,建立了面向MPL培训的TEM能力评估指标体系和能够精确界定定性指标的Fuzzy多层次评价结构.采用ANP-Fuzzy方法对CCARI41飞行学校C的MPL学生TEM能力进行评估.结果表明,威胁管理比差错管理、非预期状态管理对MPL学生TEM能力的影响大,同时,该方法能够有效区分学生自身不同方面及不同学生间的管理能力差异.此外,借助Super Decisions软件也可用于其他训练单元的效果评估. 相似文献
340.