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提出一种利用先验方差信息进行测量数据处理中粗差估计的新方法——先验方差待定参数法。该方法无需进行最小二乘和假设检验,计算简便。从基本原理出发,给出其数学模型,然后通过3个算例,与QUAD法等其他常用的粗差估计方法进行对比,证明该方法的可靠性和实用性。 相似文献
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5种红树植物对Cu、Zn、Pb积累特征研究 总被引：1，自引：0，他引：1
大量研究表明红树植物对重金属具有一定的吸附功能。本研究选取东寨港红树林保护区为研究区域,选择不同年龄阶段的5种不同红树植物,分别是木榄(Bruguiera gymnorrhiza)、海莲(Brugui-era sexangula)、秋茄(Kandelia obovata)、角果木(Ceriops tagal)、桐花树(Aegiceras corniculatum),通过对不同类型、不同树龄阶段的红树植物组织(根、枝、叶)及其林下土壤样品的采集,分析测定样品中重金属元素Cu、Zn、Pb的含量,从而计算红树植物对土壤中重金属的富集系数,分析不同红树植物对重金属的吸附能力大小。结果表明:不同的植物类型及不同植物生长期对重金属吸附功能具有明显差异,其中大龄角果木表现为最大,小龄角果木次之,而中龄桐花树最小。不同植物组织中大龄角果木的根部对Cu的吸附能力最大,最小的是大龄木榄叶;对Zn的吸附能力最大的是小龄海莲枝,最小的是大龄木榄根;大龄角果木枝对Pb的吸附系数最大,中龄木榄根最小。总体而言,5种红树植物对重金属(Cu、Zn、Pb)的总吸附能力大小表现为:角果木>海莲>秋茄>桐花树>木榄,其中富集系数最大的角果木总值为5.8869,最小的木榄总值为2.4342。 相似文献
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Being a primary producer, Microphytobenthos (MPB) play an important role in the benthic ecosystem of mangrove swamps. The temporal and vertical distribution of MPB biomass, expressed as chlorophyll a (Chla), was investigated in mangrove swamps on the Qi’ao island and the Futian Mangrove Nature Reserve, Guangdong Province, South China. Both locations are situated in the Zhujiang (Pearl River) Estuary. For each location, bi-monthly sampling was carried out at four sites during low tide period. Except one site on the Qi’ao Island, which was in Phragmites australis marsh, all sites were in mangrove swamps. The Chl a concentration in surface (0-1 cm) sediment ranged from 0.2 μg/cm 3 to 8.3 μg/cm3 in the Qi’ao Island and from 2.1 μg/cm3 to 15.6 μg/cm3 in the Futian Mangrove Reserve. The peak Chl a concentration occurred in winter or early spring, while the lowest Chl a concentration, with a value of about one quarter of the peak, was observed in summer or early autumn. The vertical distribution of Chl a concentration exhibited an exponential decline with depth, which indicated a muddy sediment with high organic matter, and the slope of the curve was positively related to Chl a concentration in the surface sediment. The MPB biomass of the Qi’ao Island was significantly lower than that of the Futian Mangrove Reserve. Our results suggest that the overlaying water quality might influence the MPB biomass in surface sediments. 相似文献
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利用2003-01?2014-12 CSR和JPL的RL06 Mascon解、RL06球谐系数(SH)解及level-3等6种GRACE时变重力场模型数据和GPM数据产品,分别计算长江流域的水储量和降雨变化,并利用广义三角帽方法分析GRACE数据的不确定性,同时计算水储量亏损指数(WSDI),以监测和分析长江流域干旱的... 相似文献
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摘 要： 基于概括函数模型,从Helmert型方差分量估计原理导出处理同类观测值包含多个方差分量的估计公式,即扩展的Helmert型方差分量通用公式,并给出其简化通用公式及特殊情况。 相似文献
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The applicability of using NARX neural network to forecast GRACE terrestrial water storage anomalies
Natural Hazards - The Gravity Recovery and Climate Experiment (GRACE) satellite has proven adept at monitoring, characterizing, and predicting hydrological variables. This paper attempted to... 相似文献
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Natural Hazards - Drought and flood events are two extreme climate phenomena which usually bring enormous economic and social loss. For meeting the goal of flood and drought prevention, the... 相似文献
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