Gauss-Markov模型参数的岭型广义逆估计及其优良性     

归庆明  郭建锋 《测绘科学》2002,(3)

本文继续文献 [10 ]的工作 ,进一步讨论了测量平差 Gauss- Markov模型参数岭型广义逆估计的若干性质 ,如允许性、优效性、相对效率、抗干扰性等等 ,得到了许多重要结论。计算结果表明 ,在设计阵呈病态时 ,岭型广义逆估计确能明显改善 L S估计  相似文献   

混流式转轮中流场的大涡模拟   总被引：1，自引：0，他引：1       下载免费PDF全文

张昌兵  杨永全  鞠小明  桂林 《水科学进展》2002,13(6):675-681

建立了基于微可压缩流体理论的相对运动的大涡模拟方法,并对混流式转轮流场进行了三维非恒定粘性数值模拟,计算方法采用了有限体积法和预测-校正方法,对固体边壁的处理使用了“壁函数”法。得到了混流式转轮的三维速度场和压力分布,与k-ε模型计算结果进行比较表明,所建立的相对运动的大涡模拟方法对转轮性能预测更加精确、合理,对转轮改型设计具有十分重要的参考价值。  相似文献   

高精度重磁测量在油气勘探中的应用效果   总被引：1，自引：0，他引：1  

邱毅  史元鹏  梁德永  桂顺晴  吴俊海  赵伟森  刘宽厚 《物探与化探》2002,26(5):340-343

在某工区进行了高精度重磁油气勘查,推断出断裂体系、密度界面和预测含油气古潜山,取得找油气突出效果,显示出重磁勘查具有的快速高效特点和有效性,对同类或相似地区的油气勘探工作有启迪和借鉴作用。  相似文献   

裂隙(EDA)介质P波地震记录数值模拟及波场特征分析     

杜正聪  何义中  贺振华  桂志先 《新疆地质》2002,20(Z1):117-120

通过对潜山面和内幕EDA介质地面地震记录数值模拟及其波场特征分析,在了解地震波场的动力学特征对裂缝介质的敏感性基础上,确定主要以振幅,其次是频率的地震波动力学特征为裂缝检测被检参数,以均方振幅与中心频率作为检验检测结果正确与否的评价参数,为建立裂缝检测方法奠定了理论基础.  相似文献   

高精度局部区域GPS水准计算方法的探讨   总被引：3，自引：0，他引：3  

归庆明  郭建锋  隋立芬  孟凡玉 《测绘科学》2001,26(1):20-22

针对现有各种 GPS水准存在的缺陷 ,我们运用现代计算数学的最新研究成果 ,提出了一种新的 GPS水准 B样条最小二乘拟合法。通过对我国西南某地区的 GPS测量成果进行处理的具体结果可以看出 ,该方法是一种更适用于高精度 GPS水准的拟合方法  相似文献   

Plagioclase replacement textures in partially eclogitised gabbros from the Sanddal mafic-ultramafic complex, Greenland Caledonides   总被引：1，自引：0，他引：1  

H. M. Lang  J. A. Gilotti 《Journal of Metamorphic Geology》2001,19(5):497-517

The Sanddal mafic‐ultramafic complex (SMUK) is a cluster of variably eclogitised mafic and ultramafic bodies that comprise the westernmost known eclogite facies locality in the North‐East Greenland eclogite province (NEGEP). Although there are no true eclogites in the SMUK, we interpret three distinct textural types of plagioclase replacement to record sequential stages in adjustment of SMUK olivine gabbro‐norites to eclogite facies conditions. The earliest stage, in which plagioclase was replaced by omphacite/spinel symplectite before nucleation of garnet (Type 1A & 1B) has not previously been described. Documentation of this texture provides clear evidence that, at least in some cases, garnet nucleation is delayed relative to nucleation of omphacite and is a rate‐limiting step for eclogitisation. Type 1C domains were produced by scattered nucleation of garnet in the same sample. In Type 2 domains, plagioclase was replaced by a layered corona with an outer layer of garnet, an inner layer of omphacite and an interior of inclusion‐rich plagioclase. In Type 3 domains, the omphacite layer was overgrown by the garnet rim, and omphacite is preserved only as inclusions in garnet. In more coarse grained leucogabbros, recrystallization was more complete, plagioclase replacement textures were less localised, and could not be divided into distinct stages. Plagioclase replacement in SMUK samples was not isochemical, and required diffusion of at least Mg and Fe from replacement of mafic phases in the surroundings. Strong compositional gradients in garnet reflect disequilibrium and were controlled by the different diffusion rates of Mg/Fe and Ca, different local chemical environments, and progress of the plagioclase breakdown reaction. The presence of small amounts of hydrous minerals (amphibole, phlogopite and clinozoisite) in local equilibrium in plagioclase domains of most SMUK samples indicates that a small amount of H₂O was present during high pressure metamorphism.  相似文献   

内蒙古乌拉山金矿带铅同位素地球化学研究   总被引：2，自引：0，他引：2       下载免费PDF全文

郎殿有 《地质找矿论丛》1992,7(1):93-102

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Empirical relationships between diversity of invertebrate communities and altitude in rivers: Application to biomonitoring     

Claude Lang  Olivier Reymond 《Aquatic Sciences - Research Across Boundaries》1993,55(3):188-196

The relationships between the diversity of invertebrate communities and the altitude of sampling sites were analysed in 438 benthic samples, collected between 1982 and 1991, in 56 rivers of western Switzerland. Diversity, estimated from total number of taxa (genus or family) and from number of taxa intolerant of pollution, was positively correlated with increasing altitude. In contrast, density of human population and the level of organic pollution were negatively correlated with increasing altitude. Therefore, the upstream increase of invertebrate diversity was attributed to the decrease of human population which is the main source of organic pollution. In this study, altitude was used, instead of organic pollution, to predict diversity. Empirical relationships between diversity and altitude were applied to surveys of water quality to describe the general altitudinal pattern characteristic for each region and to single out anomalous sites and rivers. In addition, changes in the altitudinal patterns of diversity can be used to monitor the recovery of rivers from pollution.  相似文献   

Big Earth data: disruptive changes in Earth observation data management and analysis?     

Martin Sudmanns  Dirk Tiede  Stefan Lang  Helena Bergstedt  Georg Trost  Hannah Augustin 《International Journal of Digital Earth》2020,13(7):832-850

ABSTRACT

Turning Earth observation (EO) data consistently and systematically into valuable global information layers is an ongoing challenge for the EO community. Recently, the term ‘big Earth data’ emerged to describe massive EO datasets that confronts analysts and their traditional workflows with a range of challenges. We argue that the altered circumstances must be actively intercepted by an evolution of EO to revolutionise their application in various domains. The disruptive element is that analysts and end-users increasingly rely on Web-based workflows. In this contribution we study selected systems and portals, put them in the context of challenges and opportunities and highlight selected shortcomings and possible future developments that we consider relevant for the imminent uptake of big Earth data.  相似文献   

Preliminary study on assessment of nutrient transport in the Taihu Basin based on SWAT modeling   总被引：4，自引：0，他引：4  

LAI Geying  YU Ge  GUI Feng 《中国科学D辑(英文版)》2006,49(Z1)

With the Taihu Basin as a study area, using the spatially distributed and mechanism-based SWAT model, preliminary simulations of nutrient transport in the Taihu Basin during the period of 1995-2002 has been carried out. The topography, soil, meteorology and land use with industrial point pollution discharge, the loss of agricultural fertilizers, urban sewerage, and livestock drainages were all considered in the boundary conditions of the simulations. The model was calibrated and validated against water quality monitoring data from 2001 to 2002. The results show that the annual total productions of nitrogen (TN) and phosphorus (TP) into Lake Taihu are 40000t and 2000t respectively. Nutrient from the Huxi Region is a major resource for Lake Taihu. The non-point source (surface source) pollution is the main form of catchment sources of nutrients into Lake Taihu, occupied TN 53% and TP 56% respectively. TN and TP nutrients from industrial point pollution discharge are 30% and 16%, and sewerage in both forms of point source and non-point source are TN 31 % and TP 47%. Both the loss of agricultural fertilizers and livestock drainages from the catchment should be paid more attention as an important nutrient source. The results also show that SWAT is an effective model for the simulation of temporally and spatially nutrient changes and for the assessment of the trends in a catchment scale.  相似文献