Due to its popularity and high crack sensitivity, 6061 aluminum alloy was selected as a test material for the newly developed double-sided arc welding (DSAW) process. The microstructure, crack sensitivity, and porosity of DSAW weldments were studied systematically. The percentage of fine equiaxed grains in the fully penetrated welds is greatly increased. Residual stresses are reduced. Porosity ...

We characterized the poroelastic deformation of six cores from three formations associated with the Bakken play in the Williston Basin (the Lodgepole, Middle Bakken, and Three Forks formations). All are low-porosity, low-permeability formations, but vary considerably in clay, kerogen, and carbonate content. The experimental program simulated reservoir stress changes associated with depletion an...

The upscaling process of mass transport with chemical reaction in porous media is carried out using the method of volume averaging under diffusive and dispersive conditions. We study cases in which the (first-order) reaction takes place in the fluid phase that saturates the porous medium or when the reaction occurs at the solid-fluid interface. The upscaling effort leads to average transport eq...

The residual porosity is an unavoidable phenomenon of the components produced by powder metallurgy process which in turn largely affects the strength property of the same. Now a day it is possible to control porosity of powder metallurgy components and retain them to desired amount when required. The porosity of a powder metallurgy component is greatly depends on the sintering temperature. In t...

The main aim of this survey paper is to give basic information about properties and applications of σ-porous sets in Banach spaces (and some other infinite-dimensional spaces). This paper can be considered a partial continuation of the author’s 1987 survey on porosity and σ-porosity and therefore only some results, remarks, and references (important for infinite-dimensional spaces) are repeated...

The effects of a porous fence with a nonuniform porosity on flow fields are investigated numerically. First, an experiment with a non-uniform porous fence located in a wind tunnel is performed to obtain a reference data set. Then, a numerical model that utilizes the finite volume schemewith a weakly compressible-flowmethod to solve the continuity and momentum equations is developed. The numeric...

The validity of estimating the solid phase diffusion coefficient, D s , of a lithium intercalation electrode from impedance measurement by a modified electrochemical impedance spectroscopy ~EIS! method is studied. A macroscopic porous electrode model and concentrated electrolyte theory are used to simulate the synthetic impedance data. The modified EIS method is applied for estimating Ds . The ...

The diffusive properties of anaerobic methanogenic and sulfidogenic aggregates present in wastewater treatment bioreactors were studied using diffusion analysis by relaxation time-separated pulsed-field gradient nuclear magnetic resonance (NMR) spectroscopy and NMR imaging. NMR spectroscopy measurements were performed at 22 degrees C with 10 ml of granular sludge at a magnetic field strength of...

Tragopogon pratensis is a small herbaceous plant that uses wind as the dispersal vector for its seeds. The seeds are attached to parachutes that increase the aerodynamic drag force and increase the total distance travelled. Our hypothesis is that evolution has carefully tuned the air permeability of the seeds to operate in the most convenient fluid dynamic regime. To achieve final permeability,...

In this study the physical and thermal properties of baobab (Adansonia digitata) fruit pulp powder which are essential for designing engineering processes, material handling, storage, equipment design and fabrication were determined. The physical properties, namely, mean particle size, bulk density, true density and porosity were determined. Also, angle of repose and coefficient of friction wer...