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921.
Sangram H. Patil Kaushik BanerjeeDasharath P. Oulkar Shubhangi B. PatilManjusha R. Jadhav Rahul H. SavantPandurang G. Adsule Madhukar B. Deshmukh 《Journal of chromatography. A》2009,1216(12):2307-2319
A multiresidue method is described for simultaneous estimation of 83 pesticides and 12 dioxin-like polychlorinated biphenyls (PCBs) in red and white wines. The samples (20 mL wine, acidified with 20 mL 1% HCl) were extracted with 10 mL ethyl acetate (+20 g sodium sulphate) and cleaned by dispersive solid-phase extraction (DSPE) with anhydrous calcium chloride and Florisil successively. The final extract (5 mL) was solvent exchanged to 1 mL of cyclohexane:ethyl acetate (9:1), further cleaned by DSPE with 25 mg primary secondary amine sorbent and analyzed by gas chromatography–time-of-flight mass spectrometry (GC–TOF-MS) within 31 min run time. The limits of quantification of most analytes were ≤10–20 μg/L. Acidification of wine prior to extraction prevented hydrolysis of organophosphorous pesticides as well as dicofol, whereas treatment with CaCl2 minimized the fatty acid co-extractives significantly. Solvent exchange to cyclohexane:ethyl acetate (9:1) further minimized the co-extractives. Recoveries at 5, 10 and 20 ng/mL were >80% for most analytes except cyprodinil, buprofezin and iprodione. The expanded uncertainties at 10 ng/mL were <20% for most analytes. Intra-laboratory precision in terms of Horwitz ratio of all the analytes was below 0.5, suggesting ruggedness of the method. Effectively, the method detection limit for most analytes was as low as up to 1 ng/mL in both red and white wine, except for cyfluthrin and cypermethrin. 相似文献
922.
923.
R. M. HILLARY 《Natural Resource Modeling》2012,25(4):574-598
Abstract Using an exploitation rate (not fishing mortality) based virtual population analysis (VPA) algorithm, which is itself a generalization of the Pope approximation to the original VPA equations, I show how to derive variance estimates for the key VPA outputs (recruitment, SSB, exploitation rates) given variance information on the key inputs (catch‐at‐age/terminal exploitation rates). Given the alternative VPA algorithm permits closed‐form solutions for the outputs in terms of the inputs, the delta method is employed to obtain the variance estimates, removing the need for complex simulation techniques. Using North Sea herring data as an example, the method’s utility is demonstrated by exploring the impact of aging error in the catch data and tuning error on the precision of estimates of SSB, recruitment and exploitation rates, and the parameters of the stock‐recruit relationship. 相似文献
924.
The equivalence between the interval-valued fuzzy set (IVFS) and the intuitionistic fuzzy set (IFS) is exploited to study linear programming problems involving interval uncertainty modeled using IFS. The non-membership of IFS is constructed with three different viewpoints viz., optimistic, pessimistic, and mixed. These constructions along with their indeterminacy factors result in S-shaped membership functions in the fuzzy counterparts of the intuitionistic fuzzy linear programming models. The solution methodology of Yang et al. [45], and its subsequent generalization by Lin and Chen [33] are used to compute the optimal solutions of the three fuzzy linear programming models. 相似文献
925.
雷宏田 《中国无机分析化学》2012,2(1)
讨论了采用电感耦合等离子体发射光谱法测定铜合金中锆量分析结果不确定度产生的原因。建立了数学模型,对测量重复性,标准溶液,标准曲线变动性,试液体积,试样称量,数字修约等引起的不确定分量进行评定,计算了合成标准不确定度和扩展不确定度,并给出铜合金中锆量测定结果的报告。评定结果表明:测量重复性,标准曲线线性回归引起的不确定度对总不确定度影响最大。所以,在测定中应进行多次平行测定,特别注意标准曲线的校正和绘制校准曲线所用标准样品的选择。 相似文献
926.
927.
928.
本文介绍了用板式电势差计测量电池电动势和内阻中直线拟合参数的不确定度的评定方法,并用图解法和最小二乘法求得的结果进行比较,得出评定方法的可行性与优缺点. 相似文献
929.
The multi-agent information fusion (MAIF) system can alleviate the limitations of a single expert system in dealing with complex situations, as it allows multiple agents to cooperate in order to solve problems in complex environments. Dempster–Shafer (D-S) evidence theory has important applications in multi-source data fusion, pattern recognition, and other fields. However, the traditional Dempster combination rules may produce counterintuitive results when dealing with highly conflicting data. A conflict data fusion method in a multi-agent system based on the base basic probability assignment (bBPA) and evidence distance is proposed in this paper. Firstly, the new bBPA and reconstructed BPA are used to construct the initial belief degree of each agent. Then, the information volume of each evidence group is obtained by calculating the evidence distance so as to modify the reliability and obtain more reasonable evidence. Lastly, the final evidence is fused with the Dempster combination rule to obtain the result. Numerical examples show the effectiveness and availability of the proposed method, which improves the accuracy of the identification process of the MAIF system. 相似文献
930.
本文在通胀环境和连续时间模型假设下,研究股票价格波动率具有奈特不确定对投资者的最优消费和投资策略的影响.首先在通胀环境和股票价格波动率具有奈特不确定的条件下,建立最优消费与投资问题的随机控制数学模型,得到了最优消费与投资所满足的HJB方程,并在常相对风险厌恶效用的情形下,获得最优化问题值函数的显式解.其次在通胀环境中当股价波动率具有奈特不确定时,得到了含糊厌恶的投资者是基于股价波动率的上界作出决策,并给出了投资者的最优投资和消费策略.最后在给定参数的条件下,对所得结果进行数值模拟和经济分析. 相似文献