ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • Artikel  (39)
  • kriging  (36)
  • Chemistry
  • EARTH RESOURCES AND REMOTE SENSING
  • General Chemistry
  • 1995-1999  (17)
  • 1980-1984  (21)
  • 1970-1974  (1)
  • 1950-1954
  • 1935-1939
  • Geologie und Paläontologie  (39)
Sammlung
  • Artikel  (39)
Datenquelle
Schlagwörter
Verlag/Herausgeber
Erscheinungszeitraum
Jahr
Thema
  • 1
    Digitale Medien
    Digitale Medien
    Analytical expressions of conditional mean, covariance, and sample functions in geostatistics (1996)
    Springer
    Stochastic environmental research and risk assessment 10 (1996), S. 279-294 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Linear estimation ; interpolation ; kriging ; splines ; conditional
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract This work presents analytical expressions for the best estimate, conditional covariance function, and conditional realizations of a function from sparse observations. In contrast to the prevalent approach in kriging where the best estimates at every point are determined from the solution of a system of linear equations, the best-estimate function can be represented analytically in terms of basis functions, whose number depends on the observations. This approach is computationally superior when graphing a function estimate and is also valuable in understanding what the solution should look like. For example, one can immediately see that all “singularities” in the best-estimate function are at observation points.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01581870
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 2
    Digitale Medien
    Digitale Medien
    Simulation of normal distributed smooth fields by Karhunen-Loéve expansion in combination with kriging (1997)
    Springer
    Stochastic environmental research and risk assessment 11 (1997), S. 459-482 
    Details
    ISSN: 1436-3259
    Schlagwort(e): Karhunen-Loéve expansion ; Empirical Orthogonal Functions ; stochastic simulation ; gaussian fields ; analytical covariance functions ; eigenfunctions ; kriging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Energietechnik , Geographie , Geologie und Paläontologie
    Notizen: Abstract Simulation of multigaussian stochastic fields can be made after a Karhunen-Loéve expansion of a given covariance function. This method is also called simulation by Empirical Orthogonal Functions. The simulations are made by drawing stochastic coefficients from a random generator. These numbers are multiplied with eigenfunctions and eigenvalues derived from the predefined covariance model. The number of eigenfunctions necessary to reproduce the stochastic process within a predefined variance error, turns out to be a cardinal question. Some ordinary analytical covariance functions are used to evaluate how quickly the series of eigenfunctions can be truncated. This analysis demonstrates extremely quick convergence to 99.5% of total variance for the 2nd order exponential (‘gaussian’) covariance function, while the opposite is true for the 1st order exponential covariance function. Due to these convergence characteristics, the Karhunen-Loéve method is most suitable for simulating smooth fields with ‘gaussian’ shaped covariance functions. Practical applications of Karhunen-Loéve simulations can be improved by spatial interpolation of the eigenfunctions. In this paper, we suggest interpolation by kriging and limits for reproduction of the predefined covariance functions are evaluated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02428429
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 3
    Digitale Medien
    Digitale Medien
    Analysis of otolith chemistry in Nassau grouper (Epinephelus striatus) from the Bahamas and Belize using solution-based ICP-MS (1999)
    Springer
    Coral reefs 18 (1999), S. 171-178 
    Details
    ISSN: 1432-0975
    Schlagwort(e): Key words Otolith ; Chemistry ; ICP-MS ; Stock discrimination ; Epinephelus striatus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie
    Notizen: Abstract  We examined the utility of otolith minor and trace element chemistry, assayed with inductively coupled plasma mass spectrometry (ICP-MS), as a means of delineating population structure in the Nassau grouper (Epinephelus striatus). We characterized the elemental composition of otoliths collected in 1993 from three locations in Exuma Sound, Bahamas and from Glover Reef, Belize in 1995. A single location in Exuma Sound was sampled in 1994 to test temporal variability in otolith composition. Five elements (Ca, Zn, Sr, Ba and Pb) were routinely detected, at levels significantly above background, by solution-based ICP-MS. Results from analysis of variance of elemental data, expressed as a ratio to Ca, indicated that there were no significant differences among the Exuma locations for any element, but significant variability was found between Glover Reef and the pooled Exuma localities for Zn/Ca, Sr/Ca and Ba/Ca ratios. Significant inter-annual differences at one Exuma Sound location was restricted to Ba/Ca ratios. Discriminant function analysis correctly classified 86% and 95% of the Belize and pooled Exuma sites, respectively. Otoliths from Belize were characterized by low Zn/Ca and high Ba/Ca and Pb/Ca ratios compared to otoliths from fish collected in Exuma Sound. Although differences in Ba levels may be related to upwelling at Glover Reef, more data are needed to definitely link otolith composition with regional differences in water chemistry.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003380050176
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 4
    Digitale Medien
    Digitale Medien
    The importance of energetic particle precipitation on the chemical composition of the middle atmosphere (1980)
    Springer
    Pure and applied geophysics 118 (1980), S. 128-151 
    Details
    ISSN: 1420-9136
    Schlagwort(e): Galactic cosmic rays ; Solar proton events ; Particle precipitation ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract An assessment is made of the relative contribution of certain classes of energetic particle precipitation to the chemical composition of the middle atmosphere with emphasis placed on the production of odd nitrogen and odd hydrogen species and their subsequent role in the catalytic removal of ozone. Galactic cosmic radiation is an important source of odd nitrogen in the lower stratosphere but since the peak energy deposition occurs below the region where catalytic removal of O3 is most effective, it is questionable whether this mechanism is important in the overall terrestrial ozone budget. The precipitation of energetic solar protons can periodically produce dramatic enhancement in upper stratospheric NO. The long residence time of NO in this region of the atmosphere, where catalytic interaction with O3 is also most effective, mandates that this mechanism be included in future modelling of the global distribution of O3. Throughout the mesosphere the precipitation of energetic electrons from the outer radiation belt (60°≲Λ≲70°) can sporadically act as a major local source of odd hydrogen and odd nitrogen leading to observable O3 depletion. Future satellite studies should be directed at simultaneously measuring the precipitation flux and the concomitant atmosphere modification, and these results should be employed to develop more sophisticated models of this important coupling.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01586448
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 5
    Digitale Medien
    Digitale Medien
    Turbulent mixing of reactive gases in the convective boundary layer (1997)
    Springer
    Boundary layer meteorology 85 (1997), S. 197-222 
    Details
    ISSN: 1573-1472
    Schlagwort(e): Turbulence ; Chemistry ; Closure ; Convective boundary layer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract We study the interactions of chemistry and turbulent mixing of tracersin the convective boundary layer with a second-order closure model,including higher order chemistry terms. In order to limit the number of predictive equations we prescribe the profiles for ¯w¯Θ, ¯w¯θ ¯θ and the lengthscale l. However, for model validation we treat temperature and humidity asinert tracers, and compare the results with profiles observed during theAir Mass Transformation Experiment, and with similarity expressions for thesurface layer. We find good agreement of the mean profiles, but the (co-)variances are slightly underpredicted. Furthermore, the model usesdiagnostic equations expressing third moments of concentration in terms ofsecond moments and their vertical derivatives. They are compared withlarge-eddy model results, showing good agreement and, therefore, thesimplifications are justified. The model is applied to the transport of two gases subject to one bimolecular reaction. The importance of concentration correlations on themean transformation rate is studied. For two gases diffusing in oppositedirections we find for moderate and fast chemistry a 50% and90% decreased transformation rate due to the negatively correlatedconcentrations. These values are similar to large-eddy results of Schumannand Sykes et al. For two bottom-up tracers we find that the covariance ofboth reactive species is either positive or negative, increasing or reducingthe effective transformation rate depending on the Damköhler number (the ratio of the turbulent and the chemistry timescale). A significantdirect influence of chemistry on the flux divergence is found in bothcases. According to the model the effective transport to mid-levels of theboundary layer is increased when two reactive tracers diffuse in oppositedirections, and decreased in the case of two bottom-up tracers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1000414710372
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 6
    Digitale Medien
    Digitale Medien
    Trend-surface analysis (1971)
    Springer
    Mathematical geology 3 (1971), S. 215-226 
    Details
    ISSN: 1573-8868
    Schlagwort(e): autocorrelation ; kriging ; regionalized variables ; trend analysis ; geostatistics ; general geology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract This paper is largely an exposition of the work of the French geostatistian G. Matheron and his school in English and at a simpler mathematical level. The probability theory on which it is based is essentially all contained in the references cited, most of which will be unfamiliar to mathematical geologists. The important method of ‘universal kriging” is explained intuitively. The genuine statistical problems, which have yet to be overcome, are pointed out.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02045792
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 7
    Digitale Medien
    Digitale Medien
    Statistical and geostatistical methods applied to the exploration work of the Nanisivik Zn-Pb mine, Baffin Island, Canada (1980)
    Springer
    Mathematical geology 12 (1980), S. 321-337 
    Details
    ISSN: 1573-8868
    Schlagwort(e): geostatistics ; kriging ; variogram analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract The Nanisivik Pb-Zn deposit at Strathcona Sound, northern Baffin Island, Canada, is an orebody that is an S-shaped lens 3000 m long, 75 m wide, and 2–20 m thick. It is an epigenetic karst channel filling. Total reserves are 6.9 million short tons of 14.12% Zn, 1.4% Pb, and 1.77 oz of Ag per ton. The mine was brought into production in 1976 at a rate of 2000 short tons per day. In the preproduction phase variogram studies based only on surface holes indicated a random distribution. For the evaluation of grades and for the determination of the confidence limits, classic statistical procedures were applied. Since the drilling density was different in different ore zones, a model was developed to test the effect of different drill hole spacings on the uncertainties in the present value in a discounted cash flow model. After the initial development and mining stage, structures could be recognized in semivariograms. Studies for a best drilling grid showed that the pattern of 25 ×20 m used in the mine could be extended to 35 ×35 m, taking into account that eight stopes are mined simultaneously. For ore reserve calculations weighing factors were calculated by kriging for six universally applicable geometric situations. Only the drill holes within a block and immediately surrounding it were taken into account. A test in a well-known zone yielded satisfactory results. A test to predict highs and lows of the grade accurately enough to optimally place the pillars failed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01029419
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 8
    Digitale Medien
    Digitale Medien
    Lognormal kriging—the general case (1982)
    Springer
    Mathematical geology 14 (1982), S. 475-499 
    Details
    ISSN: 1573-8868
    Schlagwort(e): kriging ; lognormal estimation ; conservation of lognormality
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract A theoretical study of the general case of the estimation of regionalized variables with a lognormal distribution is presented. The results of this study are compared to those obtained assuming conservation of lognormality. The numerical significance of the different solutions is illustrated by several simple examples.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01077535
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 9
    Digitale Medien
    Digitale Medien
    Variogram models for regional groundwater geochemical data (1982)
    Springer
    Mathematical geology 14 (1982), S. 629-644 
    Details
    ISSN: 1573-8868
    Schlagwort(e): variogram ; kriging ; interpolation ; contouring ; inverse distance weighting ; geochemical gradient
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Four variogram models for regional groundwater geochemical data are presented. These models were developed from an empirical study of the sample variograms for more than 10 elements in groundwaters from two geologic regions in the Plainview quandrangle, Texas. A procedure is given for the estimation of the variogram in the isotropic and anisotropic case. The variograms were found useful for quantifying the differences in spatial variability for elements within a geologic unit and for elements in different geologic units. Additionally, the variogram analysis enables assessment of the assumption of statistical independence of regional samples which is commonly used in many statistical procedures. The estimated variograms are used in computation of kriged estimates for the Plainview quadrangle data. The results indicate that an inverse distance weighting model was superior for prediction than simple kriging with the particular variograms used.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01033884
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 10
    Digitale Medien
    Digitale Medien
    The combination of sampling and kriging in the regional estimation of coal resources (1982)
    Springer
    Mathematical geology 14 (1982), S. 87-106 
    Details
    ISSN: 1573-8868
    Schlagwort(e): coal ; geostatistics ; kriging ; regional estimation ; systematic sampling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Two-dimensional systematic sampling of small plots followed by the kriging of those plots may be employed to obtain regional estimates of coal resources and measures of the accuracy of the estimates. The use of sampling makes large savings in computation possible. Two case studies involving the estimation of coal tonnage are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01083946
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 11
    Digitale Medien
    Digitale Medien
    Geostatistics as a tool to define various categories of resources (1983)
    Springer
    Mathematical geology 15 (1983), S. 131-143 
    Details
    ISSN: 1573-8868
    Schlagwort(e): Geostatistics ; resource classification ; mineral resources ; kriging ; resource definitions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Definition of “measured” and “indicated” resources tend to be vague. Yet, the calculation of such categories of resources in a mineral deposit calls for specific technical criteria, the selection of which depends upon the method of evaluation. This paper discusses how a geostatistical methodology provides the technical criteria required to classify reasonably assured resources by levels of assurance of their existence. A preliminary discussion concludes that the reasonably assured resources of a mineral deposit should be classified locally as in the traditional approach. However, the size of local volumes should not correspond to the elementary grid unit of drill holes but if possible to the minimum unit of selection that can be supported by the chosen mining method. The “level of confidence” of the reasonably assured resources can be quantitatively represented and determined by the estimation variance, one of the most important tools of geostatistics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01030079
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 12
    Digitale Medien
    Digitale Medien
    Kriging of water levels in the Souss aquifer, Morocco (1983)
    Springer
    Mathematical geology 15 (1983), S. 537-551 
    Details
    ISSN: 1573-8868
    Schlagwort(e): kriging ; drift ; least squares ; residuals ; water table
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Universal kriging is applied to water table data from the Souss aquifer in central Morocco. The procedure accounts for the spatial variability of the phenomenon to be mapped. With the use of measured elevations of the water table, an experimental variogram is constructed that characterizes the spatial variability of the measured water levels. Spherical and Gaussian variogram models are alternatively used to fit the experimental variogram. The models are used to develop contour maps of water table elevations and corresponding estimation variances. The estimation variances express the reliability of the kriged water table elevation maps. Universal kriging also provides a contour map of the expected elevation of the water table (drift). The differences between the expected and measured water table elevations are called residuals from the drift. Residuals from the drift are compared with residuals obtained by more traditional least-squares analysis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01031176
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 13
    Digitale Medien
    Digitale Medien
    Robust kriging—A proposal (1984)
    Springer
    Mathematical geology 16 (1984), S. 3-18 
    Details
    ISSN: 1573-8868
    Schlagwort(e): Geostatistics ; kriging ; robust estimation ; time series
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Geological data frequently have a heavy-tailed normal-in-the-middle distribution, which gives rise to grade distributions that appear to be normal except for the occurrence of a few outliers. This same situation also applies to log-transformed data to which lognormal kriging is to be applied. For such data, linear kriging is nonrobust in that (1)kriged estimates tend to infinity as the outliers do, and (2)it is also not minimum mean squared error. The more general nonlinear method of disjunctive kriging is even more nonrobust, computationally more laborious, and in the end need not produce better practical answers. We propose a robust kriging method for such nearly normal data based on linear kriging of an editing of the data. It is little more laborious than conventional linear kriging and, used in conjunction with a robust estimator of the variogram, provides good protection against the effects of data outliers. The method is also applicable to time series analysis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01036237
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 14
    Digitale Medien
    Digitale Medien
    Smoothing and interpolation by kriging and with splines (1984)
    Springer
    Mathematical geology 16 (1984), S. 601-615 
    Details
    ISSN: 1573-8868
    Schlagwort(e): kriging ; splines ; interpolation ; smoothing ; prediction ; Green's function
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Let scalar measurements at distinct points x1, ⋯, xn be y1, ⋯, yn.We may look for a smooth function f(x)that goes through or near the points (xi, yi).Kriging assumes f(x)is a random function with known (possibly estimable) covariance function (in the simplest case). Splines assume a definition of the smoothness of a nonrandom function f(x).An elementary explanation is given of the fact that spline approximations are special cases of the solution of a kriging problem.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01029320
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 15
    Digitale Medien
    Digitale Medien
    Cross validation of kriging in a unique neighborhood (1983)
    Springer
    Mathematical geology 15 (1983), S. 687-699 
    Details
    ISSN: 1573-8868
    Schlagwort(e): cross validation ; kriging ; moving neighborhood ; unique neighborhood
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Cross validation is an appropriate tool for testing interpolation methods: it consists of leaving out one data point at a time, and determining how well this point can be estimated from the other data. Cross validation is often used for testing “moving neighborhood” kriging models; in this case, each unknown value is predicted from a small number of surrounding data. In “unique neighborhood” kriging algorithms, each estimation uses all the available data; as a result, cross validation would spend much computer time. For instance, with ndata points it would cost at least the resolution of nsystems of n × nlinear equations (each with a different matrix).Here, we present a much faster method for cross validation in a unique neighborhood. Instead of solving nsystems n × n,it only requires the inversion of one n × nmatrix. We also generalized this method to leaving out several points instead of one.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01033232
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 16
    Digitale Medien
    Digitale Medien
    Cokriging of aquifer transmissivities from field measurements of transmissivity and specific capacity (1984)
    Springer
    Mathematical geology 16 (1984), S. 19-35 
    Details
    ISSN: 1573-8868
    Schlagwort(e): groundwater ; geostatistics ; cokriging ; kriging ; transmissivity ; specific capacity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract This paper presents a new application of the cokriging technique for constructing maps of aquifer transmissivity from field measurements of transmissivity and specific capacity. The technique is illustrated using data from Yolo Basin, California. Cokriging is well-suited for estimating undersampled variables. To improve the accuracy of the estimation, cokriging considers the spatial auto-correlation of the variable to be estimated and the spatial cross-correlation between the variable to be estimated and other, better-sampled variables. Consequently, in regions that lack data of the variable to be estimated, accurate estimation can still be made on the basis of auto- and cross-correlation. In addition, estimation variances can be obtained with a little additional computation effort.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01036238
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 17
    Digitale Medien
    Digitale Medien
    A geostatistically based approach to the identification of aquifer transmissivities in Yolo Basin, California (1984)
    Springer
    Mathematical geology 16 (1984), S. 125-137 
    Details
    ISSN: 1573-8868
    Schlagwort(e): kriging ; cokriging ; hydrology ; groundwater
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract A geostatistically based approach is developed for the identification of aquifer transmissivities in Yolo Basin, California. The approach combines weighted least-squares with universal kriging and cokriging techniques in an overall scheme that (1)considers a prioriknown information on aquifer transmissivity and specific capacities of wells, (2)considers uncertainties in water level and transmissivity data, and (3)estimates the reliability of the generated transmissivity values. Minimization of a global least-squares function that incorporates calibration and plausibility criteria leads to a transmissivity map that shows a good agreement with pumping-test results.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01032212
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 18
    Digitale Medien
    Digitale Medien
    Analysis of nonintrinsic spatial variability by residual kriging with application to regional groundwater levels (1984)
    Springer
    Mathematical geology 16 (1984), S. 499-521 
    Details
    ISSN: 1573-8868
    Schlagwort(e): Spatial variability ; nonintrinsic ; nonstationary ; drift ; kriging ; residuals ; groundwater levels
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract A method for obtaining pointwise or spatially averaged estimates of a nonintrinsic function is introduced based on residual kriging. The method relies on a stepwise iterative regression process for simultaneously estimating the global drift and residual semivariogram. Estimates of the function are then obtained by solving a modified set of simple kriging equations written for the residuals. The modification consists of replacing the true variogram in the kriging equations by the variogram of the residual estimates as obtained from the iterative regression process. The method is illustrated by considering groundwater levels in an Arizona aquifer. The results are compared with those obtained for the aquifer by the generalized covariance package BLUEPACK-3D.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01886329
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 19
    Digitale Medien
    Digitale Medien
    Transition probability-based indicator geostatistics (1996)
    Springer
    Mathematical geology 28 (1996), S. 453-476 
    Details
    ISSN: 1573-8868
    Schlagwort(e): cokriging ; cross-covariance ; cross-variogram ; kriging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Traditionally, spatial continuity models for indicator variables are developed by empirical curvefitting to the sample indicator (cross-) variogram. However, geologic data may be too sparse to permit a purely empirical approach, particularly in application to the subsurface. Techniques for model synthesis that integrate hard data and conceptual models therefore are needed. Interpretability is crucial. Compared with the indicator (cross-) variogram or indicator (cross-) covariance, the transition probability is more interpretable. Information on proportion, mean length, and juxtapositioning directly relates to the transition probability: asymmetry can be considered. Furthermore, the transition probability elucidates order relation conditions and readily formulates the indicator (co)kriging equations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02083656
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 20
    Digitale Medien
    Digitale Medien
    Analysis and Estimation of Natural Processes with Nonhomogeneous Spatial Variation Using Secondary Information (1998)
    Springer
    Mathematical geology 30 (1998), S. 57-76 
    Details
    ISSN: 1573-8868
    Schlagwort(e): vector random fields ; generalized covariances ; permissibility criteria ; kriging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Natural processes encountered in mining, hydrogeologic, environmental, etc. applications usually are poorly known because of scarcity of data over the area of interest. Therefore, stochastic estimation techniques are the tool of choice for a careful accounting of the heterogeneity and uncertainty involved. Within such a framework, a better utilization of all available data concerning the process of interest and all other natural processes related to it, is of primary importance. Because many natural processes show complicated spatial trends, the hypothesis of spatial homogeneity cannot be invoked always, and the more general theory of intrinsic spatial random fields should be employed. Efficient use of secondary information in terms of the intrinsic model requires that suitable permissibility criteria for the generalized covariances and cross-covariances are satisfied. A set of permissibility criteria are presented for the situation of two intrinsic random fields. These criteria are more general and comprehensive than the ones currently available in the geostatistical literature. A constrained least-square technique is implemented for the inference of the generalized covariance and cross-covariance parameters, and a synthetic example is used to illustrate the methodology. The numerical results show that the use of secondary information can lead to significant reductions in the estimation errors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1021761305044
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 21
    Digitale Medien
    Digitale Medien
    Quality mapping of the Ryytimaa dolomite in western Finland (1996)
    Springer
    Mathematical geology 28 (1996), S. 477-499 
    Details
    ISSN: 1573-8868
    Schlagwort(e): Fennoscandia ; kriging ; indicators ; indicator principal components simulation ; geostatistics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract The Ryytimaa dolomite formation in western Finland is mined for fertilizing purposes in agriculture. Ordinary kriging, indicator kriging, and indicator principal components simulation were used to map the dolomite quality. The fertilizing properties depend on the relative amounts of MgO and neutralizing CaO in dolomite. Based on the chemical composition the dolomite is divided into six quality classes according to the Finnish legislation. This quality classification is only partially in accordance with the three populations inferred from the distributions of the MgO, CaO, and neutralizing CaO contents. These populations probably represent compositionally different dolomite layers, now forming complicated fold interference structures that are visible on the kriged maps. The mapping of the quality, and thus, selective mining of the dolomite deposit is possible using the quality classification based on the three populations. In contrast, selective mining of the dolomite based on the legislation is difficult—at least with techniques used in this study.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02083657
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 22
    Digitale Medien
    Digitale Medien
    Robust estimation of the variogram: I (1980)
    Springer
    Mathematical geology 12 (1980), S. 115-125 
    Details
    ISSN: 1573-8868
    Schlagwort(e): Geostatistics ; kriging ; robust estimation ; variogram
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract It is a matter of common experience that ore values often do not follow the normal (or lognormal) distributions assumed for them, but, instead, follow some other heavier-tailed distribution. In this paper we discuss the robust estimation of the variogram when the distribution is normal-like in the central region but heavier than normal in the tails. It is shown that the use of a fourth-root transformation with or without the use of M-estimation yields stable robust estimates of the variogram.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01035243
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 23
    Digitale Medien
    Digitale Medien
    Geostatistical estimation of parameters for hydrologic transport modeling (1981)
    Springer
    Mathematical geology 13 (1981), S. 415-428 
    Details
    ISSN: 1573-8868
    Schlagwort(e): geostatistics ; hydrologic transport ; kriging ; radioactive waste disposal
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract A significant part of the work of evaluating a geologic formation as a potential repository for hazardous wastes is the modeling of contaminant transport in the surrounding media in the event the repository is breached. The transport equations that are commonly used are deterministic functions. However, because the data can vary within the area being considered, there is a degree of uncertainty associated with the results obtained from the contaminant transport models. There are several ways to incorporate uncertainties into the transport equations, but they assume that distributions and parameters such as variances and covariances are known. This paper discusses the application of geostatistical spatial estimation techniques to estimate quantities used in transport modeling. The techniques are illustrated on data from an electric analog simulation of a two-dimensional ground water system. Geostatistical methods were used to estimate potential and hydraulic conductivity surfaces from data generated from the simulation of the ground water system. Although the two surfaces were highly dependent through Darcy's Law, they were estimated independently. Independent verification of the two surfaces showed that they approximately satisfied the required conservation of mass condition that: ∇ ⋅ v = 0.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01079645
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 24
    Digitale Medien
    Digitale Medien
    Geostatistical case studies of the advantages of lognormal-de Wijsian kriging with mean for a base metal mine and a gold mine (1982)
    Springer
    Mathematical geology 14 (1982), S. 547-555 
    Details
    ISSN: 1573-8868
    Schlagwort(e): geostatistics ; kriging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Parallel variogram analyses, block kriging, and follow-up studies were effected for the lead content of part of the Prieska copper-zinc ore body and for the gold content of the highly variable Breef in a section of the Loraine gold mine, based first on untransformed values and second on logarithmically transformed values using the lognormal-de Wijsian model. For both models the effect was also analyzed of using the population mean or ignoring it. Practical follow-up comparisons confirm theoretical considerations and show that on these mines conditional biases can be eliminated conveniently by kriging with mean; also that the lognormal-de Wijsian model with mean gives the best results.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01033878
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 25
    Digitale Medien
    Digitale Medien
    Two methods with different objectives: Splines and kriging (1983)
    Springer
    Mathematical geology 15 (1983), S. 245-257 
    Details
    ISSN: 1573-8868
    Schlagwort(e): kriging ; splines ; measurement errors ; generalized covariance ; structural identification
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract When drawing a contour map from a set of irregularly spaced data points, two methods are often used: The first corresponds to a rather aesthetic criterion and consists of obtaining contour lines which will be as “smooth”as possible and will honor the data points. This generally is the objective of the draftsman, and it can be automatically performed by the method of spline interpolation. The other method, used in kriging, is to compute the Best Linear Unbiased Estimator (B.L.U.E.),that is, to obtain a map as accurate as possible. Is it possible, in practice, to predict whether the aesthetic map will also be accurate? In this paper, we first examine the theoretical point of view: Spline interpolation is equivalent to kriging with a given (generalized)covariance. We then take an example to show how this question can be answered in practice: by testing how well the spline covariance is suited to the data.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01036069
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 26
    Digitale Medien
    Digitale Medien
    Integration of mineral resource data for Kasmere Lake area, Northwest Manitoba, with emphasis on uranium (1983)
    Springer
    Mathematical geology 15 (1983), S. 25-45 
    Details
    ISSN: 1573-8868
    Schlagwort(e): Discriminant analysis ; autocorrelation ; kriging ; multiple regression ; uranium ; mineral resources
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Geological and geophysical data digitized by Fabbri (1981)are augmented by eleven lakesediment geochemical variables in a quantitative study of the Kasmere Lake—Whiskey Jack Lake area, NW Manitoba. Each of 33 geological map units (Archean and Aphebian igneous and metamorphic rocks)have a fairly distinct multivariate geochemical and geophysical signal, as shown by discriminant analysis which is able to “recover” the geological map from the geophysical and geochemical data. Autocorrelation analysis of the geochemical variables, after removing a quadratic trend, indicate that copper, nickel, uranium, and cobait have a zone of influence from 15 to 30 km or more, with a marked anisotropy parallel to geological, geophysical, and structural trends which run NE-SW, parallel to the Wollaston fold belt. The observed uranium autocorrelation coefficients are modeled as a two-dimensional exponential function with elliptical contours. A trend-signal-noise model is applied to the lake-sediment uranium using kriging on residuals from the quadratic trend. A map comparing the resulting lake-sediment uranium signal with radiometric uranium/thorium patterns indicates considerable overlap and a generally good prediction of known uranium occurrences. In areas with a strong lake-sediment uranium signal, Aphebian metasediments have a somewhat different multivariate geochemical character from Archean and Hudsonian igneous and metamorphic rocks, suggesting a method of removing areas from the signal underlain by granites that may be economically uninteresting. Logistic and stepwise regression experiments based on a control area which includes most of the presently reported occurrences are used to predict areas favorable for uranium exploration.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01030074
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 27
    Digitale Medien
    Digitale Medien
    Kriging in a global neighborhood (1984)
    Springer
    Mathematical geology 16 (1984), S. 249-265 
    Details
    ISSN: 1573-8868
    Schlagwort(e): kriging ; moving neighborhood ; global neighborhood ; geostatistics ; automatic contouring
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract The kriging estimator is usually computed in a moving neighborhood; only the data near the point to be estimated are used. This moving neighborhood approach creates discontinuities in mapping applications. An alternative approach is presented here, whereby all points are estimated using all the available data. To solve the resulting large linear system the kriging estimator is expressed in terms of the inverse of the covariance matrix. The covariance matrix has the advantage of being positive definite and the size of system which can be solved without encountering numerical instability is substantially increased. Because the kriging matrix does not change, the estimator can be written in terms of scalar products, thus avoiding the more time-consuming matrix multiplications of the standard approach. In the particular case of a covariance which is zero for distances greater than a fixed value (the range), the resulting banded structure of the covariance matrix is shown to lead to substantial computational savings in both run time and storage space. In this case the calculation time for the kriging variance is also substantially reduced. The present method is extended to the nonstationary case.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01032690
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 28
    Digitale Medien
    Digitale Medien
    Application of fuzzy clustering and fuzzy classification to evaluate the provenance of glacial till (1984)
    Springer
    Mathematical geology 16 (1984), S. 283-301 
    Details
    ISSN: 1573-8868
    Schlagwort(e): Bayesian classifiers ; classification ; cluster analysis ; cluster validity ; fuzzyc means ; fuzzyc varieties ; fuzzy covariances ; geochemical prospecting ; glacial till ; kriging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract To evaluate the provenance of glacial till, the trace element content of magnetite was used. Magnetite was present in all known rock types and all till samples in the area investigated. By using fuzzy-set theory it was possible to group samples of magnetite taken from bedrock into relatively homogeneous and geologically meaningful groups and also, by fuzzy classification, to relate the till samples to the rocks in such a way that the relative contribution of each rock type to the till is estimated. Each rock and till sample is assigned a membership value between 0 and 1 for each rock type. The membership values, for a certain rock type in the till, are then interpolated by kriging onto maps. Magnetites from skarns associated with sulfide ores especially are rather distinct, and so a map of such membership values for till unveils all known ore deposits some 1–5 km “downstream”in the general direction of the ice flow. Other anomalies show up which cannot be related to hitherto known ores or mineralizations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01032692
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 29
    Digitale Medien
    Digitale Medien
    Robustness of variograms and conditioning of kriging matrices (1984)
    Springer
    Mathematical geology 16 (1984), S. 809-822 
    Details
    ISSN: 1573-8868
    Schlagwort(e): variogram ; robustness ; kriging ; conditioning number
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Current ideas of robustness in geostatistics concentrate upon estimation of the experimental variogram. However, predictive algorithms can be very sensitive to small perturbations in data or in the variogram model as well. To quantify this notion of robustness, nearness of variogram models is defined. Closeness of two variogram models is reflected in the sensitivity of their corresponding kriging estimators. The condition number of kriging matrices is shown to play a central role. Various examples are given. The ideas are used to analyze more complex universal kriging systems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01036706
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 30
    Digitale Medien
    Digitale Medien
    Trend removal in spatially correlated datasets (1996)
    Springer
    Mathematical geology 28 (1996), S. 111-132 
    Details
    ISSN: 1573-8868
    Schlagwort(e): discriminant analysis ; kriging ; principal component analysis ; robust M-estimation ; separation of mixed populations ; spatial trend
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Typically, datasets originated from mining exploration sites, industrially polluted and hazardous waste sites are correlated spatially over the region under investigation. Ordinary kriging (OK) is a well-established geostatistical tool used for predicting variables, such as precious metal contents, biomass, species counts, and environmental pollutants at unsampled spatial locations based on data collected from the neighboring sampled locations at these sites. One of the assumptions required to perform OK is that the mean of the characteristic of concern is constant for the entire region under consideration (e.g., there is no spatial trend present in the contaminant distribution across the site). This assumption may be violated by dalasets obtained from environmental applications. The occurrence of spatial trend in a dataset collected from a polluted site is an indication of the presence of two or more statistical populations (strata) with significantly different mean concentrations. Use of OK in these situations can result in inaccurate kriging estimates with higher SDs which, in turn, can lead to incorrect decisions regarding all subsequent environmental monitoring and remediation activities. A univariate and a multivariate approach have been described to identify spatial trend that may be present at the site. The trend then is removed by subtracting the respective means from the corresponding populations. The results of OK before and after trend removal are being compared. Using a real dataset, it is shown that standard deviations (SDs) of the kriging estimates obtained after trend removal are uniformly smaller than the corresponding SDs of the estimates obtained without the trend removal.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02273526
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 31
    Digitale Medien
    Digitale Medien
    Dynamic stochastic estimation of physical variables (1996)
    Springer
    Mathematical geology 28 (1996), S. 341-365 
    Details
    ISSN: 1573-8868
    Schlagwort(e): stochastic ; dynamic ; space/time ; random fields ; kriging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract A fundamental problem facing the physical sciences today is analysis of natural variations and mapping of spatiotemporal processes. Detailed maps describing the space/time distribution of groundwater contaminants, atmospheric pollutant deposition processes, rainfall intensity variables, external intermittency functions, etc. are tools whose importance in practical applications cannot be overestimated. Such maps are valuable inputs for numerous applications including, for example, solute transport, storm modeling, turbulent-nonturbulent flow characterization, weather prediction, and human exposure to hazardous substances. The approach considered here uses the spatiotemporal random field theory to study natural space/time variations and derive dynamic stochastic estimates of physical variables. The random field model is constructed in a space/time continuum that explicitly involves both spatial and temporal aspects and provides a rigorous representation of spatiotemporal variabilities and uncertainties. This has considerable advantages as regards analytical investigations of natural processes. The model is used to study natural space/time variations of springwater calcium ion data from the Dyle River catchment area, Belgium. This dataset is characterized by a spatially nonhomogeneous and temporally nonstationary variability that is quantified by random field parameters, such as orders of space/time continuity and random field increments. A rich class of covariance models is determined from the properties of the random field increments. The analysis leads to maps of continuity orders and covariances reflecting space/time calcium ion correlations and trends. Calcium ion estimates and the associated statistical errors are calculated at unmeasured locations/instants over the Dyle region using a space/time kriging algorithm. In practice, the interpretation of the results of the dynamic stochastic analysis should take into consideration the scale effects.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02083205
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 32
    Digitale Medien
    Digitale Medien
    Geostatistical regionalization of glacial aquitard thickness in northwestern Germany, based on fuzzy kriging (1996)
    Springer
    Mathematical geology 28 (1996), S. 437-452 
    Details
    ISSN: 1573-8868
    Schlagwort(e): geostatistics ; regionalization ; fuzzy ; kriging ; hydrogeology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract In many instances hydrogeological parameters obtained by conventional methods for selected localities within an aquifer or an aquitard are not sufficient for adequate regionalization at the scale of the entire layer. Here, we demonstrate an application of the fuzzy kriging method in regionalization of hydrogeological data, in which the set of conventional, crisp values is supplemented by imprecise information subjectively estimated by an expert. It is believed that such an approach eventually may reflect the real-world conditions more closely than a traditional crisp-value approach, because the former does not impose exactness artificially on phenomena which are diffuse by their nature. Spatial interpolation was done for the thickness of one of the major aquitards (till and glaciolacustrine clay) in northwestern Germany. The dataset consists of 329 crisp values from boreholes supplemented by 172 imprecise values defined as fuzzy numbers. It is demonstrated that the reliability of regionalization was higher, compared to regionalization performed with the crisp dataset only. Fuzzy kriging was performed with FUZZEKS (Fuzzy Evaluation and Kriging System) developed at the Ecosystem Research Center at the University of Kiel.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02083655
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 33
    Digitale Medien
    Digitale Medien
    Conditional Spectral Simulation with Phase Identification (1998)
    Springer
    Mathematical geology 30 (1998), S. 285-308 
    Details
    ISSN: 1573-8868
    Schlagwort(e): conditional simulation ; kriging ; spectral simulation ; Fast Fourier Transform ; Fourier coefficient ; phase identification
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Spectral simulation is used widely in electrical engineering to generate random fields with a given covariance spectrum. The algorithms used are fast particularly when based on Fast Fourier Transform (FFT). However, because of lack of phase identification, spectral simulation only generates unconditional realizations. Local data conditioning is obtained typically by adding a simulated kriging residual. This conditioning process requires an additional kriging at each simulated node thus forfeiting the speed advantage of FFT. A new algorithm for conditioning is proposed whereby the phase values are determined iteratively to ensure approximative data reproduction while reproducing the frequency spectrum, that is, the covariance model. A case study is presented to demonstrate the algorithm.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1021728931335
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 34
    Digitale Medien
    Digitale Medien
    A Comparison of the Sequential Gaussian and Markov-Bayes Simulation Methods for Small Samples (1998)
    Springer
    Mathematical geology 30 (1998), S. 1011-1032 
    Details
    ISSN: 1573-8868
    Schlagwort(e): spatial statistics ; stochastic simulation ; kriging ; GSLIB
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract We compared the performance of sequential Gaussian simulation (sGs) and Markov-Bayes simulation (MBs) using relatively small samples taken from synthetic datasets. A moderate correlation (approximately r = 0.70) existed between a continuous primary variable and a continuous secondary variable. Given the small sample sizes, our objective was to determine whether MBs, with its ability to incorporate the secondary information, would prove superior to SgS. A split-split-plot computer experiment was conducted to compare the two simulation methods over a variety of primary and secondary sample sizes as well as spatial correlations. Using average mean square prediction error as a measure of local performance, sGs and MBs were roughly equivalent for random fields with short ranges (2 m). As range increased (15 m) the average mean square prediction error for sGs was less than or equal to that for MBs, even when number of noncollocated secondary observations was twice the number of collocated observations. Median variance within nonoverlapping subregions was used as a measure of the local heterogeneity or surface texture of the image. In most situations sGs images more faithfully reflected the true local heterogeneity, while MBs was more erratic, sometimes oversmoothing and sometimes undersmoothing.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1021785726483
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 35
    Digitale Medien
    Digitale Medien
    Estimating spatial distributions of heterogeneous subsurface characteristics by regionalized classification of electrofacies (1995)
    Springer
    Mathematical geology 27 (1995), S. 3-22 
    Details
    ISSN: 1573-8868
    Schlagwort(e): electrofacies ; kriging ; classification ; regionalization ; geostatistics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Regionalized classification of electrofacies utilizes the statistical relationships between laboratory determined hydrologic properties and field-measured geophysical properties to estimate spatial distributions of porosity, permeability, and diagenetic characteristics. The method, illustrated with an application to the St. Peter Sandstone in the Michigan basin, combines techniques for multivariate analysis and spatial estimation. Core plug and borehole geophysical data are clustered into electrofacies that reflect the hydrologic properties and diagenetic characteristics of the formation. Electrofacies characteristics then are used to assign a class membership probability at locations where only geophysical data are available. Three-dimensional estimation of electrofacies occurrence is done by kriging datasets containing the probability of electrofacies membership at borehole locations. The discretization and kriging geometry allow three-dimensional estimation of hydrologic parameters for a large region that incorporates meter-scale heterogeneity. Finally, permeability and porosity are estimated at each grid location by probability-weighting. Because the electrofacies carry information about both the hydrologic and lithologic properties, the resulting spatial distributions provide an understanding of both the present-day flow characteristics and the extent of processes that control them.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02083565
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 36
    Digitale Medien
    Digitale Medien
    Estimation of regionalized compositions: A comparison of three methods (1995)
    Springer
    Mathematical geology 27 (1995), S. 105-127 
    Details
    ISSN: 1573-8868
    Schlagwort(e): closed data ; log-ratio ; basis method ; oil field ; kriging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract A regionalized composition is a random vector function whose components are positive and sum to a constant at every point of the sampling region. Consequently, the components of a regionalized composition are necessarily spatially correlated. This spatial dependence—induced by the constant sum constraint—is a spurious spatial correlation and may lead to misinterpretations of statistical analyses. Furthermore, the cross-covariance matrices of the regionalized composition are singular, as is the coefficient matrix of the cokriging system of equations. Three methods of performing estimation or prediction of a regionalized composition at unsampled points are discussed: (1) the direct approach of estimating each variable separately; (2) the basis method, which is applicable only when a random function is available that can he regarded as the size of the regionalized composition under study; (3) the logratio approach, using the additive-log-ratio transformation proposed by J. Aitchison, which allows statistical analysis of compositional data. We present a brief theoretical review of these three methods and compare them using compositional data from the Lyons West Oil Field in Kansas (USA). It is shown that, although there are no important numerical differences, the direct approach leads to invalid results, whereas the basis method and the additive-log-ratio approach are comparable.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02083570
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 37
    Digitale Medien
    Digitale Medien
    Approximate local confidence intervals under change of support (1995)
    Springer
    Mathematical geology 27 (1995), S. 149-172 
    Details
    ISSN: 1573-8868
    Schlagwort(e): uncertainty models ; conditional distributions ; simulation ; variogram ; kriging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Approximate local confidence intervals are constructed from uncertainty models in the form of the conditional distribution of the random variable Z given values of variables [Zi, i=1,...,n]. When the support of the variable Z is any support other than that of the data, the conditional distributions require a change of support correction. This paper investigates the effect of change of support on the approximate local confidence intervals constructed by cumulative indicator kriging, class indicator kriging, and probability kriging under a variety of conditions. The conditions are generated by three simulated deposits with grade distributions of successively higher degree of skewness; a point support and two different block supports are considered. The paper also compares the confidence intervals obtained from these methods using the most used measures of confidence interval effectiveness.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02083572
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 38
    Digitale Medien
    Digitale Medien
    Analyzing Censored Spatial Data (1999)
    Springer
    Mathematical geology 31 (1999), S. 551-561 
    Details
    ISSN: 1573-8868
    Schlagwort(e): reliability ; kriging ; Expectation-Maximization (EM) algorithm ; spatial linear model
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Spatial data that are incomplete because of observations arising below or above a detection limit occur in many settings, for example, in mining, hydrology, and pollution monitoring. These observations are referred to as censored observations. For example, in a life test, censoring may occur at random times because of accident or breakdown of equipment. Also, censoring may occur when failures are discovered only at periodic inspections. Because the informational content of censored observations is less than that of uncensored ones, censored data create difficulties in an analysis, particularly when such data are spatially dependent. Traditional methodology applicable for uncensored data needs to be adapted to deal with censorship. In this paper we propose an adaptation of the traditional methodology using the so-called Expectation-Maximization (EM) algorithm. This approach permits estimation of the drift coefficients of a spatial linear model when censoring is present. As a by-product, predictions of unobservable values of the response variable are possible. Some aspects of the spatial structure of the data related to the implicit correlation also are discussed. We illustrate the results with an example on uranium concentrations at various depths.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007516023962
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 39
    Digitale Medien
    Digitale Medien
    Conditional LAS stochastic simulation of regionalized variables in random fields (1998)
    Springer
    Computational geosciences 2 (1998), S. 37-45 
    Details
    ISSN: 1573-1499
    Schlagwort(e): conditional simulation ; regionalized variables ; local average subdivision ; kriging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Informatik
    Notizen: Abstract Ore reserves forecasts are required to aid in investment decisions, mine design and valuation, short and long term production plans and proper and efficient mill design. In random multivariable fields with limited data and high levels of uncertainty, the kriged block estimates produce a smoothing effect resulting in underestimating high values and overestimating low values. The modified conditional simulation (MCS) methodology solves these problems by simulating the random field to preserve its mean and the variance structure. The simulation model is conditioned to reproduce the data at known sample points to minimize the variability between the simulated data and the true field data. In this study, the authors develop the MCS methodology to simulate ore reserve grades using the best linear unbiased estimation (BLUE) and the local average subdivision (LAS) techniques. The MCS methodology is applied to simulate block grades in a section of the Sabi Gold Project in Zimbabwe. The results are compared with the kriged estimates for this section. Analysis of the results shows that the MCS methodology reproduces the known sample grades with minimum estimation error of 0.001 while the estimation error associated with the kriged estimates is 1.104, a 100% efficiency of the MCS method over the kriging technique.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1011537816792
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...