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1.
The sign and the magnitude of the zeta potential must be known for many engineering applications. For clay soils, it is usually
negative, but it is strongly dependent on the pore fluid chemistry. However, measurement of zeta potential time is time-consuming
and requires special and expensive equipment. In this study, the prediction of zeta potential of kaolinite has been investigated
by artificial neural networks (ANNs) and multiple regression analyses (MRAs). To achieve this, ANN and MRA models based on
zeta potential measurements of kaolinite in the presence of salt and heavy metal cations at different pH values have been
developed. The results of the models were compared with the experimental results. The performance indices, including coefficient
of determination, root mean square error, mean absolute error, and variance, were used to assess the performance of the prediction
capacity of the models developed in this study. The obtained indices make it clear that the constructed ANN models were able
to predict zeta potential of kaolinite quite efficiently and outperformed the MRA models. Results showed that ANN models can
be used satisfactorily to predict zeta potential of kaolinite as a rapid inexpensive substitute for laboratory techniques. 相似文献
2.
A great deal of early-to-mid Early Cretaceous magmatic activities have been recorded in the Zhalantun area of Inner Mongolia,while the late Early to Late Cretaceous magmatic rocks have been barely reported(Guo et al.,2018;Zhang Xiangxin et al.,2017).At present,only a few Late Cretaceous magmatic activities were reported in the Arongqi area,such as volcanic rocks of the Gushanzhen Formation.However,the Gushanzhen Formation lacks accurate isotopic age,and contemporaneous intrusive rocks has not been reported yet.In this work,we collected the volcanic rocks from the Gushanzhen Formation and contemporaneous intrusive rocks in the Zhanlantun and nearby,and aim to figure out the formation ages of volcanic rocks of the Gushanzhen Formation and accompanied intrusive rocks by analyzing zircon U-Pb isotopes(Fig.1). 相似文献
3.
The need for improved product quality in the aggregates industry is driving the search for greater automation in rock type
identification. In practice, reflectance spectra in visible and near-infrared light may reliably be used for the classification
of rock classes and their variants. Previous studies introduced statistical classification of six rock variants by means of
infrared spectra. The present investigation extends these studies to cover twelve rock types and variants of worldwide economic
importance. These were measured by visible and near-infrared light. Statistical classification of these spectra is highly
challenging due to the high number of groups and the high dimensionality of the data. In functional data analysis, spectra
are regarded as curves instead of vectors of characteristics. To obtain a compact form that is more susceptible to further
analysis, the spectra are represented by a B-spline basis. Two functional versions of linear support vector machines and penalized
functional discriminant analysis are considered for classification. The multiclass problem is addressed by margin trees and
by considering all one-against-one classifications combined with a voting strategy for testing. Since classification error
estimated by 5-fold cross-validation is very low, in particular for penalized discriminant analysis, we conclude that the
rock types can be classified reliably. 相似文献
4.
Ye Zhang 《Mathematical Geosciences》2009,41(2):145-162
A hierarchical geostatistical analysis is conducted on a high-resolution, multiscale hydraulic conductivity (ln K) map, created by scaling up an experimental stratigraphy. Unlike a previous study which evaluates ln K variograms within individual depositional environments, this study analyzes deposits (or samples) that incorporate multiple
depositional environments. Based on conductivity cutoffs selected from a global ln K histogram, an indicator map is created to divide the deposits into 4 categories: sand, silty sand, clayey silt, and clay
(Hierarchy-I). Based on facies and facies assemblage types selected using geological criteria, two more indicator maps are
created at a higher hierarchy (Hierarchy-II) to divide the deposits into 14 units and 2 units, respectively. For each sample,
its experimental ln K variogram is decomposed into 4 auto- and cross-transition component variograms. The decomposition characteristics are then
evaluated against the underlying heterogeneity and specific division rule. The analysis reveals that: (1) ln K cutoffs (sand contents of the physical stratigraphy) can be used to distinguish the shifts in dominant deposition mode; (2) sample
univariate modes depend on the choice of hierarchical division; (3) sample variograms exhibit smooth-varying correlation structures
(exponential-like variograms are observed in samples with a large variance in mean facies length); (4) the decomposition characteristics
are sensitive to the division based on conductivity cutoffs, but not sensitive to the division based on depositional environment
(For all samples, with appropriate division, the sample variogram is closely approximated by the sum of the cross-transition
component variograms.); and (5) at the Hierarchy-II level, the 2-unit division gives similar decomposition characteristics
as the 14-unit division. For the select samples, parsimony in hierarchical division is achieved at the facies assemblage scale. 相似文献
5.
6.
The computation of sparse representations of data on the sphere (e.g. topographical data) is a crucial step for further processing
such as multiple separation, migration, imaging and sparsity promoting data-recovery. The Easy Path Wavelet Transform (EPWT)
is a new tool for sparse data representation that has recently been introduced for image compression. In this paper we consider
the EPWT on spherical triangulations. It is a locally adaptive transform that works along pathways through the array of function
values and exploits the local correlations of the data in a simple appropriate manner. In our approach the usual discrete
one-dimensional orthogonal or biorthogonal wavelet transform can be applied. The EPWT can be used for defining a multiresolution
analysis on the sphere in which the scaling spaces and the wavelet spaces depend adaptively on the data. Issues of implementation
of the EPWT are also considered. 相似文献
7.
<正>Objective The Susong complex zone(SCZ)is a relatively lowgrade metamorphic unit mostly with an epidoteamphibolite facies,located in the southernmost part of the Dabie orogen.However,its rock compositions,ages,metamorphic processes and petrogenesis are still 相似文献
8.
This paper presents an approach conducive to an evaluation of the probability density function (pdf) of spatio-temporal distributions
of concentrations of reactive solutes (and associated reaction rates) evolving in a randomly heterogeneous aquifer. Most existing
approaches to solute transport in heterogeneous media focus on providing expressions for space–time moments of concentrations.
In general, only low order moments (unconditional or conditional mean and covariance) are computed. In some cases, this allows
for obtaining a confidence interval associated with predictions of local concentrations. Common applications, such as risk
assessment and vulnerability practices, require the assessment of extreme (low or high) concentration values. We start from
the well-known approach of deconstructing the reactive transport problem into the analysis of a conservative transport process
followed by speciation to (a) provide a partial differential equation (PDE) for the (conditional) pdf of conservative aqueous
species, and (b) derive expressions for the pdf of reactive species and the associated reaction rate. When transport at the
local scale is described by an Advection Dispersion Equation (ADE), the equation satisfied by the pdf of conservative species
is non-local in space and time. It is similar to an ADE and includes an additional source term. The latter involves the contribution
of dilution effects that counteract dispersive fluxes. In general, the PDE we provide must be solved numerically, in a Monte
Carlo framework. In some cases, an approximation can be obtained through suitable localization of the governing equation.
We illustrate the methodology to depict key features of transport in randomly stratified media in the absence of transverse
dispersion effects. In this case, all the pdfs can be explicitly obtained, and their evolution with space and time is discussed. 相似文献
9.
Two-dimensional Conditional Simulations Based on the Wavelet Decomposition of Training Images 总被引：2，自引：1，他引：1
Scale dependency is a critical topic when modeling spatial phenomena of complex geological patterns that interact at different
spatial scales. A two-dimensional conditional simulation based on wavelet decomposition is proposed for simulating geological
patterns at different scales. The method utilizes the wavelet transform of a training image to decompose it into wavelet coefficients
at different scales, and then quantifies their spatial dependence. Joint simulation of the wavelet coefficients is used together
with available hard and or soft conditioning data. The conditionally co-simulated wavelet coefficients are back-transformed
generating a realization of the attribute under study. Realizations generated using the proposed method reproduce the conditioning
data, the wavelet coefficients and their spatial dependence. Two examples using geological images as training images elucidate
the different aspects of the method, including hard and soft conditioning, the ability to reproduce some non-linear features
and scale dependencies of the training images. 相似文献
10.
On the Elimination of Bias Averaging-Errors in Proxy Records 总被引：2，自引：2，他引：0
Veerle Beelaerts Fjo De Ridder Nele Schmitz Maite Bauwens Frank Dehairs Johan Schoukens Rik Pintelon 《Mathematical Geosciences》2009,41(2):129-144
Knowledge of and insight into past environmental conditions can be obtained by processing and analyzing proxies. The proxies
need to be processed as precisely and accurately as possible, otherwise the conclusion of the analysis will be biased. A calibration
method which reduces bias errors in the proxy measurements due to averaging is presented. Sampling with nonzero sample sizes
causes an averaging of the true proxy signal over the volume of the sample. The method is applied on a linear synthetic record
which results in an optimal correction for frequency components ranging from the dc-frequency (DC) to one half of the sample
frequency (f
s
/2). Next, the method is tested on non-linear synthetic data where the signal is reconstructed reasonably well. Finally, the
method is applied to a real vessel density record of R.
mucronata from Makongeni, Kenya, and to a real delta deuterium record of ice core EDC from dome C, Antarctica. The method discussed
in this paper is a valuable tool for the calibration of proxy measurements; it can be applied as a correction for low resolution
measurements and expanded to other types of samples and proxies. Working with small sample sizes (high resolution) amounts
to working near the detection limit, where the signal-to-noise-ratio is low. This correction method provides an alternative
in which low resolution measurements can be upgraded to minimize the loss of information due to larger sample sizes. 相似文献
11.
12.
This paper investigates the stability of an automatic system for classifying kerogen material from images of sieved rock samples.
The system comprises four stages: image acquisition, background removal, segmentation, and classification of the segmented
kerogen pieces as either inertinite or vitrinite. Depending upon a segmentation parameter d, called “overlap”, touching pieces of kerogen may be split differently. The aim of this study is to establish how robust
the classification result is to variations of the segmentation parameter. There are two issues that pose difficulties in carrying
out an experiment. First, even a trained professional may be uncertain when distinguishing between isolated pieces of inertinite
and vitrinite, extracted from transmitted-light microscope images. Second, because manual labelling of large amount of data
for training the system is an arduous task, we acquired the true labels (ground truth) only for the pieces obtained at overlap
d=0.5. To construct ground truth for various values of d we propose here label-inheritance trees. With thus estimated ground truth, an experiment was carried out to evaluate the
robustness of the system to changes in the segmentation through varying the overlap value d. The average system accuracy across values of d spanning the range from 0 to 1 was 86.5%, which is only slightly lower than the accuracy of the system at the design value
of d=0.5 (89.07%). 相似文献
13.
This paper proposes an interpolation method based on a modified Kohonen artificial neural network, and is used to interpolate
marine gravity data on a regular grid. This method combines accuracy comparable to that of kriging with a much shorter computing
time than kriging. It is particularly efficient when both the size of the grid and the quantity of available data are large.
Under some hypotheses similar to those of kriging with a trend, the unbiasedness and optimality of the method can be demonstrated.
Comparison with kriging with a trend using marine gravity data shows similar results. Although neural interpolation is slightly
less efficient, it is more robust outside of the marine data area. 相似文献
14.
Methods of Three-part Quantitative Assessments of Undiscovered Mineral Resources: Examples from Victoria,Australia 总被引：1，自引：0，他引：1
Vladimir Lisitsin 《Mathematical Geosciences》2010,42(5):571-582
Quantitative mineral resource assessments following the 3-part form rely on grade and tonnage models and probabilistic estimates
of the number of undiscovered deposits. Assessments completed in Victoria, Australia, indicate that undiscovered mineral resources
can be effectively estimated using grade and tonnage sub-models constructed using only medium- and large-tonnage deposits.
Numbers of undiscovered deposits can be estimated on the basis of expert judgement or entirely by statistical means. Appropriate
mathematical aggregation of individual expert views, expressed at interactive expert workshops, provides robust estimates
of the number of undiscovered deposits. Underestimation of uncertainty, which is common in expert judgement, can be compensated
by the statistical modification of individual interval estimates. In this study, the linear opinion pool was used as a simple
and robust method of mathematical aggregation of multiple expert estimates of the number of undiscovered deposits. A general
regression model, which estimates numbers of undiscovered deposits based on the size of the geologically permissive area and
the median deposit tonnage, provided results generally compatible with those based on expert judgement or local deposit density
models. 相似文献
15.
Pierre Goovaerts 《Mathematical Geosciences》2008,40(1):101-128
This paper presents a methodology to conduct geostatistical variography and interpolation on areal data measured over geographical units (or blocks) with different sizes and shapes, while accounting for heterogeneous weight or kernel functions within those units. The deconvolution method is iterative and seeks the point-support model that minimizes the difference between the theoretically regularized semivariogram model and the model fitted to areal data. This model is then used in area-to-point (ATP) kriging to map the spatial distribution of the attribute of interest within each geographical unit. The coherence constraint ensures that the weighted average of kriged estimates equals the areal datum.This approach is illustrated using health data (cancer rates aggregated at the county level) and population density surface as a kernel function. Simulations are conducted over two regions with contrasting county geographies: the state of Indiana and four states in the Western United States. In both regions, the deconvolution approach yields a point support semivariogram model that is reasonably close to the semivariogram of simulated point values. The use of this model in ATP kriging yields a more accurate prediction than a naïve point kriging of areal data that simply collapses each county into its geographic centroid. ATP kriging reduces the smoothing effect and is robust with respect to small differences in the point support semivariogram model. Important features of the point-support semivariogram, such as the nugget effect, can never be fully validated from areal data. The user may want to narrow down the set of solutions based on his knowledge of the phenomenon (e.g., set the nugget effect to zero). The approach presented avoids the visual bias associated with the interpretation of choropleth maps and should facilitate the analysis of relationships between variables measured over different spatial supports. 相似文献
16.
Modeling fractured rocks with numerical methods requires some derived parameters, among which the fracture network connectivity
and the size of the representative elementary volume (REV) are both of crucial importance. Percolation and REV analyses were
made by the RepSim code. The program uses input parameters such as fractal dimension of the fracture midpoints (D
c), length exponent (E) and relative dip (α
r) data. For percolation analysis, the relative sizes of the largest percolation clusters have been calculated by stochastic
realizations of the simulated fracture networks with different parameter triplets. Furthermore, fracture networks can be classified
into three major types on the basis of their (E,D
c,α
r) parameters. For the REV calculations, the porosity of the generated fracture network was calculated. The derived REV size
of a fracture network depends essentially on input parameters and shows a decreasing tendency with increasing D and E and vice versa. The method mentioned above was tested on both metamorphic samples of the Pannonian Basin and Variscan granitoid
rocks of the Mórágy Complex. Percolation values predicted for the Mórágy granite are highly sensitive to alterations in the
input parameters. The amphibolite bodies displayed a modeled fracture network with 80 to 90% of all fractures being interconnected,
while the largest achievable percolation cluster size of gneiss is less than 10%. The REV size of the amphibolite is about
20 m as a result of connected fractures filling the whole body, while gneiss has lower porosity and higher REV (approximately
70 m). 相似文献
17.
When using least squares to fit the linear model of coregionalization to multivariate geostatistical data, the sill matrices
for the different regions must be estimated, subject to the constraint that they be non-negative definite. In 1992, Goulard
and Voltz proposed and empirically examined an iterative algorithm for doing this. Although no proof was given for its convergence
or for the uniqueness of the solution to the problem, the algorithm has subsequently been extensively and successfully used.
In this paper, we prove that the minimization problem, in fact, has a unique solution and that the algorithm is guaranteed
to converge to it from any starting point. We also discuss the effect of the starting point on the speed of convergence. 相似文献
18.
Omphacite is an important mineral component of eclogite. Single-crystal synchrotron X-ray diffraction data on natural (Ca, Na) (Mg, Fe, Al)Si2O6 omphacite have been collected at the Advanced Photon Source beamlines 13-BM-C and 13-ID-D up to 47 GPa at ambient temperature. Unit cell parameter and crystal structure refinements were carried out to constrain the isothermal equation of state and compression mechanism. The third-order Birch–Murnaghan equation of state (BM3) fit of all data gives V 0 = 423.9(3) Å3, K T0 = 116(2) GPa and K T0′ = 4.3(2). These elastic parameters are consistent with the general trend of the diopside–jadeite join. The eight-coordinated polyhedra (M2 and M21) are the most compressible and contribute to majority of the unit cell compression, while the SiO4 tetrahedra (Si1 and Si2) behave as rigid structural units and are the most incompressible. Axial compressibilities are determined by fitting linearized BM3 equation of state to pressure dependences of unit cell parameters. Throughout the investigated pressure range, the b-axis is more compressible than the c-axis. The axial compressibility of the a-axis is the largest among the three axes at 0 GPa, yet it quickly drops to the smallest at pressures above 5 GPa, which is explained by the rotation of the stiffest major compression axis toward the a-axis with the increase in pressure. 相似文献
19.
Two algorithms are outlined, each of which has interesting features for modeling of spatial variability of rock depth. In
this paper, reduced level of rock at Bangalore, India, is arrived from the 652 boreholes data in the area covering 220 sq⋅km.
Support vector machine (SVM) and relevance vector machine (RVM) have been utilized to predict the reduced level of rock in
the subsurface of Bangalore and to study the spatial variability of the rock depth. The support vector machine (SVM) that
is firmly based on the theory of statistical learning theory uses regression technique by introducing ε-insensitive loss function has been adopted. RVM is a probabilistic model similar to the widespread SVM, but where the training
takes place in a Bayesian framework. Prediction results show the ability of learning machine to build accurate models for
spatial variability of rock depth with strong predictive capabilities. The paper also highlights the capability of RVM over
the SVM model. 相似文献
20.
Abdel-Aal M.?ABDEL-KARIM Mohamed I. MOUSTAFA Adel H. El-AFANDY Mohamed G. BARAKAT 《《地质学报》英文版》2017,91(4):1326-1338
Egyptian beach ilmenite occurs in a relatively high content in the naturally highly concentrated superficial black sand deposits at specific beach zones in the northern parts of the Nile Delta at Rosetta. Microscopic study shows that the ilmenite occurs as fresh homogeneous black or heterogeneous multicoloured altered grains and exhibits three types (homogeneous, exsolved and altered) of ilmenite varieties. XRD data of ilmenite indicates their association with minor hematite and quartz, whereas leucoxene shows its association with Nb‐rutile, pseudorutile and hematite. Grain size distribution suggests a very fine sand size of >89% and 80% and a fine sand size of 10.5% and 18.3% for fresh and altered ilmenites, respectively. The density of fresh, altered ilmenite and leucoxene concentrates varies from 2.70, 2.50 to 2.40 ton/m3, suggesting a gradual decrease from high grade fresh to leucoxene and consistent with variation in magnetic susceptibility as a consequence of the leaching of iron. Mass magnetic susceptibility reveals 97.6% of ilmenite and 92% of the altered form are obtained at 0.20 and 0.48 ampere. Fresh ilmenite exhibits variable TiO2 (47.18%) and Fe2O3T (46.10%) with minor MnO, MgO and Cr2O3 (1.22, 1.10 and 0.51%). The altered ilmenite is higher in TiO2 (76.16%) and SiO2 (4.68%) and lower in Fe2O3T (14.45%), MnO, MgO and Cr2O3 (0.39, 0.52 and 0.11%) compared with the fresh form. Three concentrates of ilmenites (G1, G2 and G3) were prepared from crude ore using a Reading cross belt magnetic separator under different conditions, revealing a gradual increase of TiO2, SiO2, Al2O3 and CaO accompanied by a decrease of Fe2O3T, MgO and Cr2O3 with repetition of the separation processes. Several ore dressing techniques were carried out to upgrade the ilmenite concentrate. 相似文献