排序方式: 共有33条查询结果,搜索用时 203 毫秒
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电感耦合等离子体原子发射光谱法测定水中钡、铍、硼、钒、钴、钛、钼7种微量元素 总被引:1,自引:0,他引:1
用电感耦合等离子体原子发射光谱法测定水中Ba、Be、B、V、Co、Ti、Mo 7种元素含量,具有测定方法简便、快速、准确、精密度高、数据可靠等特点。 相似文献
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Willem Kruijer Alfred Stein Willem Schaafsma Sanne Heijting 《Environmental and Ecological Statistics》2007,14(4):399-410
Count data on a lattice may arise in observational studies of ecological phenomena. In this paper a hierarchical spatial model
is used to analyze weed counts. Anisotropy is introduced, and a bivariate extension of the model is presented. 相似文献
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Measurements of semi-volatile organic chemicals (SVOCs) were compared among 21 laboratories from 7 countries through the analysis of standards, a blind sample, an air extract, and an atmospheric dust sample. Measurement accuracy strongly depended on analytes, laboratories, and types of standards and samples. Intra-laboratory precision was generally good with relative standard deviations (RSDs) of triplicate injections <10% and with median differences of duplicate samples between 2.1 and 22%. Inter-laboratory variability, measured by RSDs of all measurements, was in the range of 2.8-58% in analyzing standards, and 6.9-190% in analyzing blind sample and air extract. Inter-laboratory precision was poorer when samples were subject to cleanup processes, or when SVOCs were quantified at low concentrations. In general, inter-laboratory differences up to a factor of 2 can be expected to analyze atmospheric SVOCs. When comparing air measurements from different laboratories, caution should be exercised if the data variability is less than the inter-laboratory differences. 相似文献
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“精密度偏性分析”是环境监测质量保证的重要手段 总被引:1,自引:0,他引:1
“精密度偏性分析”是环境监测质量保证的重要手段。通过它可以了解其方法的误差和检出限是否达到要求,同时也了解实验室和操作人员对该方法的适应性。 相似文献
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Previous research has suggested that pesticide losses at the field scale can be dominated by a small proportion of the field area. The objective of this study was to investigate whether site-specific applications (i.e. avoiding high-risk areas) at the field scale can contribute to a reduction of pesticide leaching despite uncertainty in the underlying model-based leaching risk map. Using a meta-model of the dual-permeability model MACRO, the annual average pesticide leaching concentrations were estimated for 162 sample sites on a 47 ha field. The procedure was repeated for different scenarios describing different patterns of spatial variation of degradation half-lives and the partition coefficient to soil organic carbon. To account for interpolation uncertainty, maps of predicted pesticide leaching risk were produced by the method of sequential Gaussian simulation. The results of the case study show that larger reductions of predicted leaching were achieved by site-specific application than by that of a comparable uniform dose reduction. Hence, site-specific-applications may be a feasible method to reduce pesticide leaching at the field-scale providing that the model approach gives reasonable estimates of the spatial pattern of pesticide leaching. 相似文献
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从仪器精密度、方法检出限、准确度、工作曲线线性范围等角度对总有机碳测定仪TOC-5000A(高温燃烧+非分散红外法)与Aurora 1030W(湿式氧化)的性能进行比较.研究结果显示,TOC-5000A方法检出限(0.535ppm)高于Aurora1030W(0.047ppm),且在较低有机碳浓度下(1ppm)精密度差于Aurora 1030W.但在较高有机碳浓度条件下(10ppm),TOC-5000A精密度优于Aurora 1030W.在不同水样中加入标准物质后计算方法回收率,两台仪器的测试结果均大于90%.在样品量较低的情况下,碳加入量与两台仪器响应值的线性关系均较差,响应因子随碳加入量的增加呈现显著降低的趋势,并分别在升至2μg(Aurora 1030W)与0.16μg(TOC-5000A)后达到稳定. 相似文献
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基于灰平面的事故预测方法研究 总被引:3,自引:2,他引:3
彭冬芝 《中国安全科学学报》2004,14(4):36-39
基于灰色系统理论中的灰平面概念 ,构建某一指定点的邻域系GM(1,1)系列模型 ,由模型的解得出原始数列的预测值范围 ,即灰平面并用实例比较分析了模型的精度。研究表明 ,基于灰平面的事故预测方法的优势是所需数据少 ,编程计算简便 ,模型精度较高 ,可以预测系统行为特征值未来发展的范围 ,是一种值得推广的预测方法。 相似文献
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此文利用上限法建立带毂直齿圆柱齿轮精锻过程的数学模型,并利用该模型对带毂直齿圆柱齿轮精锻过程中坯料外形尺寸和力一行程曲线进行了计算机模拟。对所得结果作了实验校核。实验结果与模拟结果吻合得较好,证明此文所建立的数学模型和模拟方法是可行的。 相似文献