Ubiquitous porosity gradients have a potentially important effect on the mixing of particle-bound tracers, such as 210Pb Mass-depth coordinates cannot be used to deal with these effects if values of the traditional mixing coefficient, D,, are required. This paper compares and evaluates three different means of dealing directly with porosity gradients while modeling bioturbation, i.e. mean const...

abstract agriculture is the largest consumer of water resources in iran. one of the best options for increasing the irrigation efficiency and better application of precipitation in arid and semi-arid areas is employing of superabsorbent polymers to soil. polymers can absorb rain and irrigation water, decrease deep percolation and increase water use efficiency. in order to investigate the effect...

Electrochemical impedance spectroscopy and gravimetric methods were carried out to analyze water uptake of thin polyurethane films separately filled with either hydrophobic or hydrophilic nano-silica. Correspondingly the impedance spectra and gravimetric data were interpreted in terms of movement of water within the coating and/or to the coating/metal interface. Although the obtained results fr...

In this study, the effects of nano-CuO (NC) on engineering properties of fibre-reinforced mortars incorporating metakaolin (MK) were investigated. The effects of polypropylene fibre (PP) were also examined. A total of twenty-six mixtures were prepared. The experimental results were compared with numerical results obtained by adaptive neuro-fuzzy inference system (ANFIS) and Primal Estimated sub...

the prediction of porosity is achieved by using available core and log data; however, the estimationof permeability is limited to the scare core data. hence, porosity and saturation data through theframework of flow units can be used to make an estimation of reservoir permeability. the purposeof this study is to predict the permeability of a carbonate gas reservoir by using physical-basedempiri...

Models on flow and transport in surface water sediments currently neglect compaction, although it is well understood that compaction is one of the major processes below the free fluid-sediment interface. Porosity changes in the sediment layers, as a result of compaction, are measured in almost all probes: porosity decreases with the distance from the surface water-sediment interface. This paper...

A three-dimensional two-phase lattice Boltzmann model (LBM) is implemented and validated for qualitative study of the fundamental phenomena of liquid water transport in the porous layer of a proton exchange membrane fuel cell (PEMFC). In the present study, the three-dimensional microstructures of a porous layer are numerically reconstructed by a random generation method. The LBM simulations foc...

In the current work, the effect of surface morphology on light emission property and absorption behavior of quasi-columnar macro-porous silicon (PS) was investigated. PS structures with different morphology were synthesized using photo-electrochemical etching method by applying different etching current densities. SEM micrographs showed that empty macro-pores size and porosity of PS layers were...