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1.
A quadtree-based image segmentation procedure (HQ) is presented to map complex environmental conditions. It applies a hierarchical nested analysis of variance within the framework of multiresolution wavelet approximation. The procedure leads to an optimal solution for determining mapping units based on spatial variability with constraints on the arrangement and shape of the units. Linkages to geostatisiics are pointed out, but the HQ decomposition algorithm does not require any homogeneity criteria. The computer implementation can be parameterized by either the number of required mapping units or the maximum within-unit variance, or it can provide a spectrum of significances of nested ANOVA. The detailed mathematical background and methodology is illustrated by a salt-affected grassland mapping study (Hortobágy, Hungary), where heterogeneous environmental characteristics have been sampled and predicted based on remotely sensed images using these principles. 相似文献
2.
C. Schnitchen D. J. Charman E. Magyari M. Braun I. Grigorszky B. Tóthmérész M. Molnár Zs. Szántó 《Journal of Paleolimnology》2006,36(1):1-17
Peatlands offer the potential for high resolution records of water balance over Holocene timescales, yet this potential is
under-exploited in many areas of the world. Within Europe, peatlands are mostly confined to areas north of 55° N, but several
areas of southern and eastern Europe contain small peatlands which may be suitable for palaeoclimatic reconstruction. In this
paper we test the potential of peatlands in the Carpathian region for deriving quantified estimates of water table changes
using testate amoebae analysis. A training set for palaeohydrological reconstruction from testate amoebae assemblages was
obtained by collecting surface samples from 13 peatlands, including 9 from Hungary and 4 from Transylvania (Romania). Using
a simple measure of mean annual water tables estimated from staining of PVC tape, we found that some peatlands were heavily
influenced by runoff and groundwater, and were therefore not suitable as modern analogues of ombrotrophic climatically sensitive
sites. The relationship between the testate amoebae assemblages in the modern samples and the environmental variables was
explored using CCA. The CCA biplot showed that the most important variables are depth to water table and moisture content,
confirming that hydrology is a key control on taxon distribution. pH was a secondary gradient. A transfer function for % moisture
and depth to water table was established and applied to fossil assemblages from a sequence from Fenyves-tető, Transylvania,
Romania. The reconstructed water table shows a number of variations which have parallels with other palaeoclimatic records
from Europe and the North Atlantic prominent phases of higher water tables are associated with the periods 8000–8300 cal BP,
3000–2500 cal BP and after 600 cal BP. We suggest that these were periods of particular intensification of westerly airflow
which affected eastern Europe as well as western and central Europe. 相似文献
3.
Zsuzsanna Szabó Nóra Edit Gál Éva Kun Teodóra Szőcs György Falus 《Environmental Earth Sciences》2018,77(12):460
CO2 geological storage is a transitional technology for the mitigation of climate change. In the vicinity of potential CO2 reservoirs in Hungary, protected freshwater aquifers used for drinking water supplies exist. Effects of disaster events of CO2 escape and brine displacement to one of these aquifers have been studied by kinetic 1D reactive transport modelling in PHREEQC. Besides verifying that ion concentrations in the freshwater may increase up to drinking water limit values in both scenarios (CO2 or brine leakage), total porosity of the rock is estimated. Pore volume is expected to increase at the entry point of CO2 and to decrease at further distances, whereas it shows minor increase along the flow path for the effect of brine inflow. Additionally, electrical conductivity of water is estimated and suggested to be the best parameter to measure for cost-effective monitoring of both worst-case leakage scenarios. 相似文献
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Molecular dynamics simulations of a 0.55 molal aqueous LiI solution have been performed at 508 K and 308 K and a density of 1.05 g/cm3. The structural changes resulting from increased temperature and pressure are discussed. 相似文献
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Experimental control in the classical igneous petrology is based on determination of the equilibrium conditions of simple — mostly 1–4 component — system. The statements based on such experiments are valid for rock products chemically not influenced by active environments. For elucidation of processes between geochemically active volatile-rich country rocks, high pressure and high temperature experiments oncomplex systems containing such active rock samples, too were performed. High pressure bombs were constructed with long and narrow container, allowing to investigate the selective migration of elements between different rock samples, even by temperature slope within the container. In these bombs different igneous, sedimentary and metamorphic rocks in contact at different temperatures and pressures were investigated. P-t relations and stability fields of different mineral facies cannot be exactly determined by phase diagrams of simple uni- or multicomponent systems, because they depend on other components and on the environments, too. The new complex experiments, however permit to assess directly the stability fields of the mineral facies. The data obtained proves that an intense selective migration of the volatiles take place even in solid samples at 550° C, in some rock associations already at 250° C, if there is a concentration gradient of volatiles between the samples. Selective migration proceeds following the principle of transvaporization, i.e. towards the partial pressures — chemical activities — of the mobile components and following the sequence of their ionic potentials. In this way, different hypomagmatic and metamorphic rocks are produced. The new kind of experiments shows that — opposite to the approaches of the classical igneous petrology — a high grade contamination of the ascending magma is possible. Contamination proceeds by transvaporization. Assimilation — Einschmelzung — mostly plays an insignificant role. Gravitative crystallization differentiation operates intensely only in the higher sections of volcanic pathways, characterized by relatively low pressures and thus by low viscosity of the magma. Contamination is intense if the ascension of magma is relatively slow as it is presumable along the oblique circumpacifique or innercarpathian andesitic structural lines. In this way, basaltic magma produces andesitic to rhyolitic rocks partly abundant in volatiles. However contamination is restricted and consequently basaltic rocks are formed if magma ascends rapidly through vertical channels as it is presumably the case with the young peripherical basalt volcanics, e.g. the innercarpathian basin system. These experiments also evidence the activation process of magma by transvaporization. Selective migration of volatiles even through solid rocks is introduced by structural pressure minimum zones towards these zones, which results in the melting of neighbouring rocks and their lifting as liquid magma until volatile supply is sufficient. 相似文献
9.
The volume and the photosensitive area of next generation detectors of the numerous rarely occurring phenomena will greatly exceed the sizes of the current experiments. These phenomena include cosmic neutrinos, atmospheric neutrinos, long-baseline neutrino beams from accelerators, geo-neutrinos, geo-reactor neutrinos, and hypothetic proton decays. Similar requirements hold for a new type of a large scanning device for homeland security and nuclear proliferation control, and for the future widely accessible medical imaging devices. Photon detectors are the most important component of such detectors. Existing photosensors are based on vacuum tubes and dynode electron multipliers that are essentially hand-made, expensive and nearly impossible to produce in large enough quantities. Silicon detectors are too small for experiments requiring a very large photosensitive area. Our laboratory is developing novel detectors with a large photosensitive area that can be mass-produced, similar to large flat panel TV displays. 相似文献
10.
Numerical models constitute the most advanced physical-based methods for modeling complex ground water systems. Spatial and/or temporal variability of aquifer parameters, boundary conditions, and initial conditions (for transient simulations) can be assigned across the numerical model domain. While this constitutes a powerful modeling advantage, it also presents the formidable challenge of overcoming parameter uncertainty, which, to date, has not been satisfactorily resolved, inevitably producing model prediction errors. In previous research, artificial neural networks (ANNs), developed with more accessible field data, have achieved excellent predictive accuracy over discrete stress periods at site-specific field locations in complex ground water systems. In an effort to combine the relative advantages of numerical models and ANNs, a new modeling paradigm is presented. The ANN models generate accurate predictions for a limited number of field locations. Appending them to a numerical model produces an overdetermined system of equations, which can be solved using a variety of mathematical techniques, potentially yielding more accurate numerical predictions. Mathematical theory and a simple two-dimensional example are presented to overview relevant mathematical and modeling issues. Two of the three methods for solving the overdetermined system achieved an overall improvement in numerical model accuracy for various levels of synthetic ANN errors using relatively few constrained head values (i.e., cells), which, while demonstrating promise, requires further research. This hybrid approach is not limited to ANN technology; it can be used with other approaches for improving numerical model predictions, such as regression or support vector machines (SVMs). 相似文献