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341.
There are three major issues in modeling solar evanescent oscillations: the variation of the intensity [I]–velocity [V] phase difference of p-modes close to the base of photosphere; the existence of a plateau of negative I–V phase differences below and between the ridges of the low-frequency p-modes; the explanation of the I–V cross-spectra of the evanescent oscillations. We present new interpretations for the first two issues, based on modeling intensity fluctuations taking steep temperature gradients, opacity, and non-adiabatic cooling into account. We also discuss consequences of our model for the explanation of power spectra and cross-power spectra of p-modes. In particular, we present evidence that the acoustic sources that generate evanescent waves produce a coherent background that explains the plateau–interridge regime of negative I–V phase difference. 相似文献
342.
The dynamical properties of electromagnetic (EM) waves in ultra-relativistic electron-positron (EP) plasmas are analytically investigated on the basis of the nonlinear governing equations obtained from a kinetic way. It is shown that the EM wave envelope will collapse and be trapped into a localized region for the modulation interaction with low frequency density variation induced by ponderomotive force. The correlation between the localized strong wave field and the pulsar radio emission is discussed. 相似文献
343.
Kopylov A. I. Kosolapov D. B. Zabotkina E. A. Romanenko A. V. Sazhin A. F. 《Oceanology》2021,61(2):220-232
Oceanology - The distribution of heterotrophic bacteria, viruses, and heterotrophic nanoflagellates was studied in the shelf waters of the East Siberian Sea along the meridional transect from the... 相似文献
344.
The current study sought to offer guidance for developing effective web-based mapping tools for wildfire warnings by identifying (1) the important content for facilitating individuals’ decision-making, and (2) the optimal interface design for ensuring usability and ease of information access. A map-based warning tool was prototyped in the Australian context, followed by a usability and effectiveness evaluation through individual interviews and verbal protocol analysis to assess participants’ interaction with the mapping interface and information in response to the simulated warning scenario. The results demonstrated variations in participants’ approaches to wildfire warning response, revealing varied information needs. Specifically, most participants relied on their own assessment of the prospective threat, requiring specific wildfire-related information before eliciting a response. In contrast, the decision of a minority of the participants was motivated by response guidance from agencies, and accurate wildfire information was less important for their response. Imperative information for both types of residents therefore needs to be highlighted in a map-based warning tool to cater to a wide audience. Furthermore, a number of heuristics were identified for designing effective interactive functions to facilitate the control of, and access to, the various maps and textual information presented on the map-based warning interface. 相似文献
345.
A low-dimensional model that describes both saturated and unsaturated flow processes in a single equation is presented. Subsurface flow processes in the groundwater, the vadose zone, and the capillary fringe are accounted for through the computation of aggregated hydrodynamic parameters that result from the integration of the governing flow equations from the bedrock to the land surface. The three-dimensional subsurface flow dynamics are thus described by a two-dimensional equation, allowing for a drastic reduction of model unknowns and simplification of the model parameterizations. This approach is compared with a full resolution of the Richards equation in different synthetic test cases. Because the model reduction stems from the vertical integration of the flow equations, the test cases all use different configurations of heterogeneity for vertical cross-sections of a soil-aquifer system. The low-dimensional flow model shows strong consistency with results from a complete resolution of the Richards equation for both the water table and fluxes. The proposed approach is therefore well suited to the accurate reproduction of complex subsurface flow processes. 相似文献
346.
Glukhov A. N. Kotov A. B. Priymenko V. V. Sal’nikova E. B. Ivanova A. A. Plotkina Yu. V. Fedoseenko A. M. 《Geotectonics》2022,56(2):178-190
Geotectonics - In our study we analyzed the composition of granitoid rocks within the Kongo magmatic zone of the Omolon median mass. The studied calc-alkaline granitoids cut through the Early... 相似文献
347.
Salt crystallisation is a major problem of deterioration in historic stone buildings, monuments and sculptures. The capillary rise of soil water is one of the primary sources of salts in stone structures, which evaporates leaving the salts behind. It has been noted that the spatial distribution profile of different species of salts crystallised in historic stone buildings is not homogeneous, i.e. different salts crystallise at different locations. The capillary transport and inhomogeneous spatial distribution of different salts in the porous building materials has been considered to be a result of solubility-dependent crystallisation; however, the factors responsible for this phenomenon are not clearly known. This paper aims to investigate the factors influencing the differential distribution of salts during capillary rise of soil water. In this study, the capillary transport of salts was simulated on two different sandstones—Locharbriggs, a Permo–Triassic, red sandstone and Stoke Hall, a Carboniferous, buff sandstone. The experiments were carried out under controlled environmental conditions to eliminate the possibility of evaporation-driven crystallisation of salts depending on their solubilities. The results indicate that fractionation or differential distribution of salts takes place even in the absence of evaporation and crystallisation. The sandstones exhibit properties like an ion exchange column, and ionic species present in the salt solution show differential distribution within the porous network of sandstone. 相似文献
348.
349.
350.
Weidong Li 《Mathematical Geosciences》2007,39(3):321-335
Multi-dimensional Markov chain conditional simulation (or interpolation) models have potential for predicting and simulating categorical variables more accurately from sample data because they can incorporate interclass relationships. This paper introduces a Markov chain random field (MCRF) theory for building one to multi-dimensional Markov chain models for conditional simulation (or interpolation). A MCRF is defined as a single spatial Markov chain that moves (or jumps) in a space, with its conditional probability distribution at each location entirely depending on its nearest known neighbors in different directions. A general solution for conditional probability distribution of a random variable in a MCRF is derived explicitly based on the Bayes’ theorem and conditional independence assumption. One to multi-dimensional Markov chain models for prediction and conditional simulation of categorical variables can be drawn from the general solution and MCRF-based multi-dimensional Markov chain models are nonlinear. 相似文献