Three-dimensional Distribution Model Research Articles

Distribution of Radiation-Induced Defects in Quartz at the ACKIO Uranium Prospect, Athabasca Basin, Saskatchewan: Tracing Uranium-Bearing Fluids

Abstract Quartz grains from the ACKIO uranium prospect, located near the eastern margin of the Athabasca Basin, Saskatchewan, have been investigated using powder X-band electron paramagnetic resonance (EPR) spectroscopy. The EPR spectra of quartz separates from samples systematically collected from the Athabasca Supergroup sandstones and the underlying metamorphosed basement reveal a suite of silicon-vacancy hole centers, which were formed by the bombardment of alpha particles emitted from the radioactive decay of uranium, thorium, and their unstable progeny. The differences in EPR signal intensities of these hole centers indicate that quartz grains received different accumulative doses of alpha particle irradiation in different locations within the ACKIO prospect. For example, quartz extracted from a mineralized sample has the highest EPR signal intensity due to the presence of disseminated uraninite. For quartz sampled at distance from uranium mineralization, the elevated intensities of the silicon-vacancy hole centers most likely indicate a temporary source of radiation, such as ancient uranium-bearing fluids. The median EPR intensities of quartz from the basement rocks at ACKIO are an order of magnitude higher than those of its counterpart from the Athabasca sandstones. Also, the EPR intensities of quartz along the sandstone–basement contact at ACKIO differ by more than two orders of magnitude, suggesting limited migration of uranium-bearing fluids along this contact in the study area. Instead, anomalously high EPR intensities in quartz close to the sandstone–basement contact and elsewhere are restricted to fault gouges and brecciated areas, suggesting that they are the structural pathways for channelized migration of ancient uranium-bearing fluids. A three-dimensional distribution model of the EPR signal intensities has been constructed to define conduits for the migration of ancient uranium-bearing fluids at ACKIO and suggest favorable targets for further exploration. These findings demonstrate the power of EPR spectroscopy in delineating pathways of uranium-bearing fluids and predicting potential mineralization targets.

Mathematical Model and Numerical Simulation Study of the Mining Area with Multiple Air Leakage Paths

The natural fire in the mining area is the main source of mine fires, and the distribution of spontaneous combustion “three zones” is a key issue in mine fire prevention and suppression. In order to study the change law of spontaneous combustion “three zones” in the mining area with multiple air leakage paths, a segmented numerical simulation method is proposed. In order to consider the common influence of various factors, we firstly establish the coupled model of oxygen consumption rate of coal relics, the regional fluidity model of the porous medium and the three-dimensional distribution model of void rate in the mining area. Then, based on this, the corresponding conditions of air leakage speed, air leakage location and oxygen concentration are set in each stage of numerical simulation. The mathematical model shows that: the oxygen consumption rate of coal shows an approximate exponential growth trend with the increase in temperature, which is proportional to the original oxygen concentration; the void rate of the mining area shows a logarithmic distribution with a tendency of “double hump” proportional coupling. The numerical simulation results show that: the width of the “oxidation zone” decreases gradually along the tendency when there is only air leakage from the working face; the smaller airflow and lower oxygen concentration in the overlying mining area will increase the width of the “oxidation zone” in the coverage area; air leakage from the shelf road will form an “oxidation zone” near the entrance of the shelf road. The leakage of air from the shelf road will form an “oxidized zone” near the entrance of the shelf road; the leakage of air from the adjacent mining area will increase the width of the overall “dispersal zone” and “oxidized zone” due to the larger air flow and higher oxygen concentration. The comparison with the monitoring data of the downhole bundle tube verifies the rationality of the mathematical model and the accuracy of the numerical simulation results.

Study on Wind Field Characteristics in a Coastal Plain Based on a New Three-Dimensional Joint Distribution Model

This paper studied the joint probability distribution of wind speed, wind direction, and wind height. The measured wind field data of a coastal plain in Zhongshan city, Guangdong Province, China, were taken as the research object. A three-dimensional joint distribution modeling method, based on the copula function and the AL (angular–linear) model, is proposed. Firstly, the wind speed is modeled by the common distribution model, and the Weibull distribution is selected. Secondly, the mvM (mixed von Mises distribution) was used to fit the wind direction probability density, and the joint distribution of wind speed and wind direction was established based on the AL model. Finally, a three-dimensional joint distribution model of wind speed, wind direction, and height was established by considering the effect of height through the copula function. The results showed that Weibull distribution can better describe the wind speed distribution in this region. The north–south wind prevailed in this region, and the probability of the main wind direction decreased with the increase in height. The joint distribution of wind speed and direction, based on the AL model, fitted well with the measured data, and the final three-dimensional distribution model had a good fitting effect.

Study on pollutant model construction and three-dimensional spatial interpolation in soil environmental survey

In site soil investigation, the construction of three-dimensional (3D)geological model and spatial three-dimensional distribution model of pollutants can help investigators to clearly and intuitively understand the morphology distribution and spatial relationship of pollutants. Four 3D interpolation methods (Krige, IDW-Shepard, FastRBF and Nearest Neighbor)are compared and studied, based on the Sb (antimony) data in soil of a polluted plot in Tianjin by using EVS-Pro. The results show that the selection of interpolation method is quite different for the calculation results of 3D interpolation model, and the cross-verification results show that the interpolation accuracy of Krig-3D interpolation model is the highest. The pollution distribution model of Sb based on interpolation results can truly reflect the actual pollution of the site and accurately help to calculate earthwork, and 3D model and visualization technology have more intuitionistic and clear display. It provides a reference and framework for the subsequent remediation and treatment of contaminated sites.

A finite element analysis on compressive properties of ECC with PVA fibers

In order to analyze the compressive performance of ECC with PVA by finite element method, in this paper the three-dimensional distribution model of PVA fiber was established by compiling the random sequence program of Matlab considering the random distribution of PVA in matrix ECC. On this basis, the finite element model of ECC was established by ABAQUS software to study the stress and deformation properties of ECC with different PVA fiber content under axial compression.

The temperature field study on the three-dimensional surface moving heat source model in involute gear form grinding

Form grinding is one of the most important finishing processes for obtaining high surface quality gears. Nevertheless, to avoid thermally induced burning and structural change poses a major challenge for this manufacturing technology. Based on the moving heat source model and the superposition principle of heat sources, a comprehensive analytical thermal model for analyzing the heat transfer mechanism of involute gear form grinding was derived. A three-dimensional distribution model of equivalent grinding heat source considering the non-linear distribution of tangential grinding force, grinding parameters, and heat partition ratio was proposed. The FEM (finite element method) simulation of the grinding temperature field was carried out to predict the grinding temperature field using a nested net heat flux equation. Research results have shown that the grinding temperature increases nonlinearly with the rolling angle increasing and the evident peak grinding zone temperature appearing near the tip of the tooth. Through the comparison with the previous experimental measurement results, it is found that the temperature distribution of analytical calculation and numerical simulation agrees well with the measured results.

Grinding motor energy saving method based on material removal model in rail grinding processes

Railway is an environmental friendly method which has been widely used in the land transportation driven by electric powers, without harmful emissions and unhoped traffic jams. And it is important to guarantee the running safety through the technology of rail grinding. However, the empirical processes have limitations on the expanded requirements of frequent and systematic rail grinding. Therefore, it is necessary to build up the rail grinding model to fill the gap between the operating parameters and desired on-theground results. In this paper, a three-dimensional distribution model has been built to get a uniform special-distribution for grains and extract one slice as the representative grinding surface, with decahedrons grains transformed from spheres. Then the cutting force model and then related power model have been achieved based on the formed grinding surface with information of grains geometry and their locations. Calculation results show that the consumed power or the consumed energy have a close relationship with grinding speeds and grinding forces, which are closely related to the grain geometry, involved grain numbers, location of grains and their cutting depth. And it comes to a conclusion that a judgment for energy-saved grinding strategy depends on the grinding aims.

A Three-Dimensional Distribution Model of Pressure on Inner Surface of Elbow Pipe Based on FLUENT

Using the methods of dimensional analysis and the FLUENT analytic software, a quantitative description method is built; the influents of parameters, including the degree of curvature k=R/d, fluid density ρ, axial angle α, circle angle β, fluid outlet pressure P0 and fluid velocity v on the distribution of pressure on inner surface of elbow pipe are studied from the simulation results; Finally, a three-dimensional distribution model of pressure which is considering the fluid characteristic and the elbow pipe geometric parameters is built by fitting the simulation data. The research conclusion lays the groundwork for strength check and structural design of the elbow pipe.

The Detailed Study for Barrier and Interlayer of Low Permeability Reservoirs in Sha-4 Formation of W81 Block, Dongpu Sag

W81 Block is located in the northern end of central uplift in Dongpu Sag and is a deep part of the Weicheng Oilfield structure. By detailed core observation and analysis of logging data characteristics, we can identify two main types of barrier and interlayer in Sha-4 Formation, including muddy barrier and interlayer and gray interlayer. This article describes the distribution characteristics of the barrier and interlayer from three aspects: plane, crosswell profile and well group distribution. The corresponding three-dimensional distribution model of the barrier and interlayer based on structural model has been constructed, which reflects the distribution rule across the barrier and interlayer and help to guide internal dig potential development of the low permeability oilfield.

Atmospheric loss of energetic electrons in the Jovian synchrotron zone

For decades, ground-based radio observations of Jovian synchrotron radiation have shown emission originating predominantly from the equatorial region and from high-latitude regions (lobes) near L∼2.5. The observations show a longitudinally asymmetric gap between the emission peaks of the lobes and the atmosphere of Jupiter. One possible explanation for these gaps is the loss of electrons through collisions with atmospheric neutrals as the electrons bounce along magnetic field lines and drift longitudinally in the presence of asymmetric magnetic fields. To assess this hypothesis, we applied the recently developed O6 and VIP4 magnetic field models to calculate the trajectories of electrons as they drift longitudinally in Jupiter's magnetic field, and derive the sizes of their equatorial drift loss cones. We then identified the shells on which electrons would be lost due to collisions with the atmosphere. The calculated drift loss cone sizes could be applied in future to the modeling of electron distribution functions in this region and could also be applied to the study of Jovian auroral zone. This method also allowed us to compute the shell-splitting effects for these drifting electrons and we find the shell-splitting to be small (⩽0.05 R J). This justifies a recent modeling assumption that particles drift on the same shells in a three-dimensional distribution model of electrons. We also compared the computed gaps with the observed gaps, and found that the atmospheric loss mechanism alone is not able to sufficiently explain the observed gap asymmetry.

Hydrogeological and ground-water resource analysis using a geotechnical database

An application of a geotechnical database system for primary evaluation of ground-water resources in a sedimentary basin is proposed. The database consists of 1200 borehole logs including geologic columns,in situ test results, ground-water level, water quality data, and resistivity logs. The Kumamoto plain, situated in southwest Japan, is chosen as a study area. The evaluation process consists of two steps: (1) modeling of shapes of water-bearing strata, and (2) modeling of distribution of physical quantity which has some relationship with the porosity of those strata. In step (1), the shapes of upper and/or lower surface of the pyroclastic flow deposits and the andesitic lava were determined, whereas the three-dimensional distribution model of resistivity was constructed from resistivity logging data obtained from 100 boreholes and using the proposed interpolation method in the step (2). An empirical equation between the porosity and the resistivity of the lava was also identified. The integration of two types of model and the empirical equation contributed to an estimate of the total volume of the ground-water under the study area.