共查询到20条相似文献，搜索用时 62 毫秒
1.
YONGDONG WANG ODD S.BORGEN BRUCE R.KOWALSKI Laboratory for Chemometrics Center for Process Analytical Chemistry Department of Chemistry BG- University of Washington Seattle WA U.S.A. Present address:Perkin-Elmer Corporation Main Avenue Norwalk CT - U.S.A. 《地理学报(英文版)》1993,(5)
Through theoretical analysis and computer simulation,this short communication comments on theresidual bilinearization(RBL)method and compares it with non-bilinear rank annihilation(NBRA)forthe treatment of second-order calibration with non-bilinear data.It is found that these two methods aremathematically equivalent but have different noise propagation properties.The second-order advantage,namely quantitation in the presence of unknown interferences,can be carried over to non-bilinear dataonly if there exists a net analyte rank(NAR)for the analyte of interest. 相似文献
2.
TENSORIAL RESOLUTION:A DIRECT TRILINEAR DECOMPOSITION 总被引：4，自引：0，他引：4
EUGENIO SANCHEZ~ BRUCE R.KOWALSKI Laboratory for Chemometrics Department of Chemistry BG-.University of Washington Seattle WA U.S.A. Mobil Research Development Corporation Paulsboro Research Laboratory Billinsport Ro Paulsboro NJ U.S.A. 《地理学报(英文版)》1990,(1)
Modern instrumentation in chemistry routinely generates two-dimensional(second-order)arrays of data.Considering that most analyses need to compare several samples,the analyst ends up with a three-dimensional(third-order)array which is difficult to visualize or interpret with the conventional statisticaltools.Some of these data arrays follow the so-called trilinear model,(?)These trilinear arrays of data are known to have unique factor analysis decompositions which correspondto the true physical factors that form the data,i.e.given the array (?),a unique solution can be found inmany cases for each order X,Y and Z.This is in contrast to the well-known second-order bilinear datafactor analysis,where the abstract solutions obtained are not unique and at best cannot be easilycompared with the underlying physical factors owing to a rotational ambiguity.Trilinear decompositions have had the disadvantage,however,that a non-linear optimization withmany parameters is necessary to reach a least-squares solution.This paper will introduce a method forreducing the problem to a rectangular generalized eigenvalue-eigenvector equation where the eigenbectorsare the contravariant form(pseudo-inverse)of the actual factors.It is shown that the method works wellwhen the factors are linearly independent in at least two orders(e.g.X_(jr),and Y_(jr) are full rank matrices).Finally,it is shown how trilinear decompositions relate to multicomponent calibration,curve resolutionand chemical analysis. 相似文献
3.
RECENT DEVELOPMENTS IN MULTIVARIATE CALIBRATION 总被引：1，自引：0，他引：1
B.R.KOWALSKI M.B.SEASHOLTZ Laboratory for Chemometrics BG- University of Washington Seattle WA U.S.A. 《地理学报(英文版)》1991,(3)
With the goal of understanding global chemical processes,environmental chemists have some of the mostcomplex sample analysis problems.Multivariate calibration is a tool that can be applied successfully inmany situations where traditional univariate analyses cannot.The purpose of this paper is to reviewmultivariate calibration,with an emphasis being placed on the developments in recent years.The inverseand classical models are discussed briefly,with the main emphasis on the biased calibration methods.Principal component regression(PCR)and partial least squares(PLS)are discussed,along with methodsfor quantitative and qualitative validation of the calibration models.Non-linear PCR,non-linear PLSand locally weighted regression are presented as calibration methods for non-linear data.Finally,calibration techniques using a matrix of data per sample(second-order calibration)are discussed briefly. 相似文献
4.
Estimating the amount of erosion experienced by a sedimentary basin during its geological history plays a key role in basin modelling. In this paper, we present a novel probabilistic approach to estimate net erosion from porosity–depth data from a single well. Our approach uses a Markov chain Monte Carlo algorithm which readily allows us to deal with imprecise knowledge of the lithology-dependent compaction parameters in a joint inversion scheme using multiple lithologies. The results using synthetic data highlight the advantages of our approach over conventional techniques for net erosion estimation: (a) uncertainties on compaction parameters can be effectively mapped into a probabilistic solution for net erosion; (b) posterior uncertainties are easy to quantify; (c) the joint inversion scheme can automatically reconcile porosity data from different lithologies. Our results also underscore the critical role of prior assumptions on controlling the retrieved estimates for net erosion. Using real data from a well in the Barents Sea, we simulate three possible scenarios of variable prior assumptions on compaction parameters to demonstrate the general applicability of our approach. Strong prior assumptions on the compaction parameters led to unrealistic estimates of net erosion for the target well, indicating the assumptions are probably inappropriate. Our preferred strategy for this dataset is to include additional data to constrain the normal compaction trend of the sediments. This provides a net erosion estimate for the target well of about 2300 m with a standard deviation of 140 m which is in line with previous studies. Finally, we discuss potential guidelines to deal with real applications in which data from normally compacted sediments are not available. One is to use our algorithm as a hypothesis-testing tool to evaluate the results under a large set of assumed compaction parameters. A second is to infer compaction parameters and net erosion simultaneously from the target well porosity data. Although appealing and successful with synthetic data, this strategy provides results which are strongly dependent on the calibration data and the geological history of the sediments sampled by the target well. 相似文献
5.
沟道等级结构与顺序结构都可看作是沟道拓扑结构,在黄土高原小流域坝系规划研究中,往往需要将Horton-Strahler的沟道分级模型与较长沟道优先的顺序编码模型进行整合。该文提出一个沟道结构假说,即在黄土高原小流域尺度上,存在一个最小集水面积与最短沟道长度的适宜取值区间,使得基于DEM提取的沟道网络上任意节点对应的较长沟道作为主沟道,其Horton-Strahler沟道等级不低于汇入支流。搜集的黄土高原丘陵沟壑区多个副区的一些典型小流域数据有效验证了上述假说,从而为实现整合等级结构与顺序结构的沟道编码模型的进一步研究提供理论基础。 相似文献
6.
This paper presents an automated classification system of landform elements based on object-oriented image analysis. First, several data layers are produced from Digital Terrain Models (DTM): elevation, profile curvature, plan curvature and slope gradient. Second, relatively homogenous objects are delineated at several levels through image segmentation. These object primatives are classified as landform elements using a relative classification model, built both on the surface shape and on the altitudinal position of objects. So far, slope aspect was not used in classification. The classification has nine classes: peaks and toe slopes (defined by the altitudinal position or the degree of dominance), steep slopes and flat/gentle slopes (defined by slope gradients), shoulders and negative contacts (defined by profile curvatures), head slopes, side slopes and nose slopes (defined by plan curvatures). Classes are defined using flexible fuzzy membership functions. Results are visually analyzed by draping them over DTMs. Specific fuzzy classification options were used to obtain an assessment of output accuracy. Two implementations of the methodology are compared using (1) Romanian datasets and (2) Berchtesgaden National Park, Germany. The methodology has proven to be reproducible; readily adaptable for diverse landscapes and datasets; and useful in respect to providing additional information for geomorphological and landscape studies. A major advantage of this new methodology is its transferability, given that it uses only relative values and relative positions to neighboring objects. The methodology introduced in this paper can be used for almost any application where relationships between topographic features and other components of landscapes are to be assessed. 相似文献
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8.
THE PERFORMANCE OF LEAST SQUARES AND ROBUST REGRESSION IN THE CALIBRATION OF ANALYTICAL METHODS UNDER NON-NORMAL NOISE DISTRIBUTIONS 总被引：1，自引：0，他引：1
By means of Monte Carlo simulations a comparison has been made between ordinary least squaresregression and robust regression. The robust regression procedure is based on the Huber estimate and iscomputed by means of the iteratively reweighted least squares algorithm. The performance of bothprocedures has been evaluated for estimation of the parameters of a calibration function and fordetermination of the concentration of unknown samples. The influence of the distributionalcharacteristics skewness and kurtosis has been studied, and the number of measurements used forconstructing the calibration curve has also been taken into account, Under certain conditions robustregression offers an advantage over least squares regression. 相似文献
9.
Evaluation of current statistical approaches for predictive geomorphological mapping 总被引：5，自引：3，他引：5
Predictive models are increasingly used in geomorphology, but systematic evaluations of novel statistical techniques are still limited. The aim of this study was to compare the accuracy of generalized linear models (GLM), generalized additive models (GAM), classification tree analysis (CTA), neural networks (ANN) and multiple adaptive regression splines (MARS) in predictive geomorphological modelling. Five different distribution models both for non-sorted and sorted patterned ground were constructed on the basis of four terrain parameters and four soil variables. To evaluate the models, the original data set of 9997 squares of 1 ha in size was randomly divided into model training (70%, n=6998) and model evaluation sets (30%, n=2999).In general, active sorted patterned ground is clearly defined in upper fell areas with high slope angle and till soils. Active non-sorted patterned ground is more common in valleys with higher soil moisture and fine-scale concave topography. The predictive performance of each model was evaluated using the area under the receiver operating characteristic curve (AUC) and the Kappa value. The relatively high discrimination capacity of all models, AUC=0.85–0.88 and Kappa=0.49–0.56, implies that the model's predictions provide an acceptable index of sorted and non-sorted patterned ground occurrence. The best performance for model calibration data for both data sets was achieved by the CTA. However, when the predictive mapping ability was explored through the evaluation data set, the model accuracies of CTA decreased clearly compared to the other modelling techniques. For model evaluation data MARS performed marginally best.Our results show that the digital elevation model and soil data can be used to predict relatively robustly the activity of patterned ground in fine scale in a subarctic landscape. This indicates that predictive geomorphological modelling has the advantage of providing relevant and useful information on earth surface processes over extensive areas, such data being unavailable through more conventional survey methods. 相似文献
10.
基于GLASS数据估算中国陆表净辐射及其空间分布分析 总被引：1，自引：0，他引：1
地表辐射收支是能量循环的重要参数,影响着地球水热平衡,是全球气候变化研究的重要方面。多数研究利用MODIS数据估算地表辐射收支,模型输入参数复杂。综合利用GLASS数据、MODIS数据和地面实测数据,采用Bisht等提出的净辐射估算方法,制订一种简单的地表辐射收支估算方案,分别计算2010年1-12月中旬卫星过境时刻中国陆表净辐射的最大值。通过改进的正弦模型将估算结果转换为日最大地表净辐射,并利用地面实测日最大净辐射值对估算结果进行了验证。研究表明：综合利用GLASS数据、MODIS数据和地面实测数据建立的地表辐射收支模型能够很好地模拟中国陆表净辐射的分布,与地面实测日最大净辐射值具有较好的一致性,平均误差为27.21 W?m-2,克服了利用其他遥感数据估算地表辐射收支输入参数复杂,数据量大的缺点,适用于大尺度地表陆表辐射收支研究。 相似文献
11.
分布式水文模拟汇流方法及应用 总被引：21，自引：4，他引：17
对于必须考虑汇流过程的分布式水文模型而言 ,其汇流模型可以分解为三个层次来讨论 :第一个层次是单元划分 ;第二个层次为汇流路径 ;第三个层次则是基于该汇流路径的汇流演算模型。基于栅格的分级运动波汇流模型是根据栅格DEM的网格单元水流流向来划分栅格等级 (汇流带 ) ,然后应用运动波模型进行逐级汇流演算。文中从可操作性的角度对栅格分级方法和运动波汇流模型进行了分析讨论 ,最后根据潮白河流域 1 981～ 1 990年资料进行了日径流过程模拟分析 ,说明该方法在理论上是合理的 ,并在应用中取得良好的模拟效果。 相似文献
12.
作为欧空局地球探测计划的一项重要任务,Cryo Sat-2卫星于2010年携带着Ku波段SIRAL(干涉/合成孔径雷达高度计)发射升空。Cryo Sat-2任务的优势在于高精度地测量两极海冰厚度以及监测南极大陆和格陵兰冰盖的变化,同时92°的近极地轨道一定程度上填补了先前遥测卫星的高纬数据缺口。本文对Cryo Sat-2卫星的科学目标、科学需求、任务概况、仪器载荷以及数据产品等方面做了详细的介绍,重点强调了Cryo Sat-2的首要载荷SIRAL和数据校准,最后探讨了Cryo Sat-2在极地领域的应用。 相似文献
13.
《地理学报(英文版)》1991,(3)
An additive model is used to express the observed value of a sample characteristic as the sum of the truesample characteristic and a value of the data collection error,commonly known as experimental error.The data uncertainty of the experimental results(or of a survey data set)is defined as the expectedsquared error.The expected squared error may change with the sample characteristic,e.g.the errormoment could be concentration-dependent.The relationship between the error variance and the analyteconcentration may not be very distinct.In such a case the data transformation to stabilize the errormoments may not be appropriate.A step function is proposed as an alternative way to represent thesecond moment of the error.The data uncertainty is defined as the weighted average of the step valuesof the second raw moment of the error,using the appropriate proportions of the routine samples asweights.The data uncertainties associated with the different data collection stages were evaluated by usingregional soil survey data. 相似文献
14.
利用2004年开展的“金塔绿洲系统能量与水分循环过程观测试验（JTEX）”所取得的资料和中尺度气象模式MM5对西北地区金塔绿洲系统进行了数值模拟研究,模拟结果较好地反映了绿洲-沙漠系统的气象场和辐射场。模拟结果显示,绿洲、沙漠的短波辐射和净辐射具有明显的日变化,而长波辐射的日变化则不很明显;绿洲、沙漠的向下短波辐射相似,峰值在1 050 W·m-2左右;绿洲向上短波辐射峰值略小,约166 W·m-2,沙漠向上短波辐射峰值约261 W·m-2;绿洲、沙漠的长波辐射相差不大,全天基本上分布在300 W·m-2左右;绿洲净辐射峰值约914 W·m-2,大于800 W·m-2左右的沙漠地区。净辐射在沙漠或绿洲同种地表类型上基本与区域一致,分布均匀,下垫面上数值相差不超过10 W·m-2。白天不同下垫面上的净辐射有较大的差别,最大差异可达100 W·m-2。 相似文献
15.
An improved algorithm for the generalized rank annihilation method(GRAM)is presented.GRAM isa method for multicomponent calibration using two-dimensional instruments,such as GC-MS.In thispaper an orthonormal base is first computed and used to project the calibration and unknown sampleresponse matrices into a lower-dimensional subspace.The resulting generalized eigenproblem is thensolved using the QZ algorithm.The result of these improvements is that GRAM is computationally morestable,particularly in the case where the calibration sample contains chemical constituents not present inthe unknown sample and the unknown contains constituents not present in the calibration(the mostgeneral case). 相似文献
16.
对宜兴市机载成像光谱数据辐进行射畸变纠正、几何精确纠正和辐射定标等预处理,获得高光谱反射率图像。利用相关系数、均方差、离散度等统计特征进行面向土地利用/土地覆盖目的的波段优选,采用高光谱像元提纯分析工具获得分类所需的终端单元,并利用终端单元进行了研究区土地利用/土地覆盖分类对比研究。研究发现:最大似然法分类精度低,整体精度为84.89%,而二进制编码、神经网络分类和光谱角分类方法精度较高,整体精度分别为87.12%,88.75%,90.41%。这说明光谱角分类是最有效的高光谱影像土地利用/土地覆盖分类方法,文章研究采用的高光谱预处理以及波段选择方法是正确的。 相似文献
17.
JERKER 《地理学报(英文版)》1990,(1)
When using hyphenated methods in analytical chemistry,the data obtained for each sample are given asa matrix.When a regression equation is set up between an unknown sample (a matrix) and a calibrationset (a stack of matrices),the residual is a matrix R.The regression equation is usually solved by minimizing the sum of squares of R.If the sample containssome constituent not calibrated for,this approach is not valid.In this paper an algorithm is presentedwhich partitions R into one matrix of low rank corresponding to the unknown constituents,and onerandom noise matrix to which the least squares restrictions are applied.Properties and possibleapplications of the algorithm are also discussed.In Part 2 of this work an example from HPLC with diode array detection is presented and the resultsare compared with generalized rank annihilation factor analysis (GRAFA). 相似文献
18.
Efficient encoding and spatial operation scheme for aperture 4 hexagonal discrete global grid system
Xiaochong Tong Ying Wang Yongsheng Zhang Tao Pei 《International journal of geographical information science》2013,27(5):898-921
Discrete global grid systems (DGGSs) are considered to be promising structures for global geospatial information representation. Square and triangular DGGSs have had the advantage over hexagonal ones in geospatial data processing over the past few decades. Despite a significant body of research supporting hexagonal grids as the superior alternative, the application thereof has been hindered partly owing to the lack of a hierarchy. This study presents an original perspective to combine two types of aperture 4 hexagonal discrete grid systems into a hierarchy. Each cell of the hierarchy is assigned a unique code using a linear quadtree that constructs the hexagonal quaternary balanced structure (HQBS). The mathematical system described by HQBS addressing and the vector operations, including addition, subtraction, multiplication, and division, are defined. Essential spatial operations for HQBS cell retrieval, transformation between HQBS codes and other coordinate systems, and arrangement of HQBS cells on spherical surfaces were studied and implemented. The accuracy and efficiency of algorithms were validated through experiments. The results indicate that the average efficiency of cell retrieval using the HQBS is higher than that using other schemes, thus proving it to be more efficient. 相似文献
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20.
Concentration estimates of components present in a sample mixture can be obtained using matrixmathematics. In the past, the condition number of the calibration matrix has been used to give anamplification factor by which uncertainties in data can work through to errors in the concentrationestimates. This paper explores an additional interpretation of condition numbers with regards tosignificant figures and rounding errors. A procedure is suggested which will always give the most accurateconcentration estimates provided the calibration matrix is not too ill-conditioned. Condition numbershave also been used by analytical chemists to discuss the error bounds for concentration estimates.Unfortunately, only one representative error bound can be approximated for all the components. Thispaper will show how to compute bounds for individual concentration estimates obtained as solutions to asystem of m equations and n unknowns. The procedure is appropriate when calibration data and sampleresponses are inaccurate. 相似文献