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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 21 for “"Dispersivity"”.
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Describing and Predicting Breakthrough Curves for non-Reactive Solute Transport in Statistically Homogeneous Porous Media
… equation (CDE) with scale-dependent dispersivity, mobile-immobile model (MIM), and the fractional convection-dispersion equation (FCDE). In order to test these modeling approaches, a prototype laboratory column system was designed for conducting miscible displacement experiments with …
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Solute transport in layered and heterogeneous soils
… either a time-dependent or distance-dependent dispersivity was considered to represent the effects of heterogeneity. In a series of simulations of transport in two-layered soils, we found that breakthrough curves (BTCs) were similar regardless of the layering sequence for all reversible and …
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Lattice Boltzmann Study of the Interstitial Hydrodynamics and Dispersion in Steady Inertial Flows in Large Randomly Packed Beds
… predict a significant increase in the lateral dispersivity with Peclet number in complete agreement with experimental data. For longitudinal dispersion, disorder is shown to lead to a slightly superlinear increase in dispersivity with Peclet number in accordance with experimental findings.
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Process Modeling of Trihalomethanes During Aquifer Storage and Recovery
… and estimated parameters such as longitudinal dispersivity were used to build a single layer, confined, homogeneous, and isotropic model to simulate trihalomethane attenuation. Trihalomethane concentrations at the well during recovery were moderately sensitive to flow rates and porosity, and …
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Stochastic modelling of contaminant transport in porous media
… commonly referred to as scale-dependent dispersivity. A particularly significant concept arising from the work is that of a natural length scale associated with velocity fluctuations, and which separates distinct short and long range dispersivity trends. To obtain full quantitative …
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HYDROGEOLOGICAL CHARACTERIZATION OF A LEGACY WASTE STORAGE SITE AND THE CHALLENGE OF COMMUNICATING UNCERTAINTY
… modelled by manipulating hydraulic conductivity, dispersivity, and recharge estimates. The results indicate hydraulic conductivity, dispersivity, and recharge all effect contaminant breakthrough times and under/overestimate breakthrough by up to 50 years. The results of the sensitivity analysis …
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Finite element modeling of contaminant transport through confined disposal facilities
… unit weight, molecular diffusion, and transverse dispersivity have little impact on contaminant transport. Other properties, such as the distribution coefficient and the longitudinal dispersivity, have only a slight to moderate impact on contaminant transport, while the coefficient of hydraulic …
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Measurement and Modeling of Nitrate-Nitrogen Transport in Subsurface Bioreactors
… transport. The storage coefficient, the dispersivity and the first-order decay coefficient were estimated as 0.18 cm-1, 0.86, 16.7 cm, and 0.2 hr-1, respectively through a nonlinear regression approach. The results of this study will lead to a better understanding of nitrate-N transport …
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Taylor-Aris dispersion in microfluidic networks
… parameters, namely the mean velocity vector U*, dispersivity dyadic D* and, if necessary, the mean volumetric solute depletion rate K*. The ease with which these discrete calculations can be performed for complex networks renders feasible parametric studies of potential microfluidic chip designs, …
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Modeling the impact of petroleum mixtures released from railroad tank car accidents on groundwater contamination and cleanup times
… TPH-water, and maximum contaminant levels, dispersivity, and solubility), and to evaluate groundwater contamination and cleanup times for four complex mixtures of concern in the railroad industry. In most cases, raising cleanup criteria concentrations and increasing dispersivity and …
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Modelling and Monitoring of Phosphorus Transport and Speciation in Soil
… The model was used to interpret a change in dispersivity and the behaviour of reactive phosphorus species on compaction.
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A Field and Numerical Study of Heat and Solute Transport in a Discrete Fracture
… channel, 1.4 mm aperture and a longitudinal dispersivity of 1 m. Both fits were achieved with similar hydraulic head rises to those measured during the field experiments. The substantial difference in flow geometry, and the need to use an unrealistic thermal conductivity is not easily …
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"Vector chromatography" : modeling micropatterned separation devices
… F acting upon the solute molecules) and the dispersivity dyadic D* (resulting from the deviation of the instantaneous position of the particle from its mean position based upon its mean velocity vector). In the present example these coefficients are studied parametrically as functions of: (i) …
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The optimal design of groundwater quality monitoring networks under conditions of uncertainty
… variance and correlation scale, the transverse dispersivity, and the size of the contaminant source.
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Preparation and characterisation of Pt-Ru/C catalysts for direct methanol fuel cells
… conditions affect structure, morphology and dispersivity of the catalyst (Wang et al., 2005). Metal organic chemical deposition methods have shown promise in improving performance of electro-catalysts (Garcia & Goto, 2003). However, it is necessary to optimise deposition conditions such as …
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An analytic model of the Cochlea and functional interpretations
… gain and decay, phase and group velocities, and dispersivity. The expressions are in terms of three model constants, which can be reduced to two constants for most applications. Spatial variation is implicitly incorporated through an assumption of scaling symmetry, which relates space and …
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HYPORHEIC FLOW, RESIDENCE TIMES AND NITROGEN REACTIONS IN A RIFFLE-POOL SEQUENCE, TRUCKEE RIVER, NV.
… all piezometer locations. Streambed porosity and dispersivity resulted in residence time uncertainty of 8.5 - 9.5 days and 5.0 - 7.7 days, respectively. The riverbed has distinct hot spots and hot moments of high biogeochemical activity in both the riffle and pool areas. Nitrate and dissolved …
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A Study of Transport of Micellar Fluids in Porous Media
Two- and three-phase relative permeabilities have been measured for a low interfacial tension brineoil- surfactant-alcohol mixture in a Berea sandstone core. The measurements were done at steady-state with a constant nominal capillary number of 10^-2. Residual phase saturation (capillary …
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Numerical study of solute transport in deformable soil liners
… results demonstrated that the longitudinal dispersivity and compressibility of the pore fluid can be significant. <br/>Furthermore, the degree of soil saturation and loading rate of the waste surcharge affect significantly the contamination advective emission, namely the cumulative …
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The Impact of Surface Modified Nanoparticles on the Performance of Polymer Solutions for Heavy Oil Recovery
… for polymer nanohybrids which improved the dispersivity of the NPs into the polymer solutions and the resistance of the polymer solutions to salinity and temperature, and 3) better understanding of the mechanisms contributing to the success of nanohybrids in chemical flooding.
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