Chemical Weathering in a Hypersaline Effluent Irrigated Dry Ash Dump: An Insight from Physicochemical and Mineralogical Analysis of Drilled Cores

Accumulation of high ionic strength effluents (brines) that require disposal in inland industries where water recycling is necessary due to scarcity is a major challenge. A coal combustion power utility in South Africa utilizing a dry ash disposal system produces 1.765 Mt of fly ash per annum and also employs the zero liquid effluent discharge policy (ZLED) to manage its liquid effluents. Fly ash is conditioned for dust suppression before being conveyed to the ash dumps with the high saline effluent. The saline effluents results from various processes employed for maximum utilization, upgrading and re-use of various mine water and industrial effluents such as RO, EDR, softening and ion exchange in an effort to adhere to ZLED policy. In the ash dumps it is further conditioned by irrigation with the high saline effluents, therefore the ash acts as a repository for the salts. This study is an attempt to understand the chemical weathering of the effluent conditioned fly ash and species mobility in a dry disposal scenario. A combination of leaching tests was performed for fresh ash and drilled cores to estimate the highly leachable species. Results from DIN-S4 tests of the fresh and weathered ash reveal that Ca, K, Na, Mg, Ba, SO42-, Se, Mo and Cr are highly leached. Leaching tests also revealed that major soluble components in the solution at equilibrium are Ca, Na, SO42- and K. Weathering profiles of the ash dump cores were observed to follow a similar trend. The greatest weathering was observed to take place at the top layer (0.55-3 m depth) in the weathered ash cores (15 years and older), showing that infiltration of rain water over time has a profound effect on the decrease of the pore water pH.  Analysis of the extracted pore water in each of the different weathered ash cores by depth indicated the mobility of several elements through the ash. Increased cation exchange capacity at 4-5 m depth suggests a transient mineralization zone.Key words:  Weathered fly ash; Pore water; Ash dumps; Hypersaline effluents; X-ray diffraction analysis; DIN-S4 test; Cation exchange capacit

Thermal compression of two-dimensional atomic hydrogen to quantum degeneracy

We describe experiments where 2D atomic hydrogen gas is compressed thermally at a small "cold spot" on the surface of superfluid helium and detected directly with electron-spin resonance. We reach surface densities up to 5e12 1/cm^2 at temperatures of approximately 100 mK corresponding to the maximum 2D phase-space density of about 1.5. By independent measurements of the surface density and its decay rate we make the first direct determination of the three-body recombination rate constant and get the value of 2e-25 cm^4/s for its upper bound, which is an order of magnitude smaller than previously reported experimental results.Comment: 4 pages, 4 postscript figures, bibliography (.bbl) file, submitted to PR

Computer-implemented land planning system and method

US10380270B2Algorithms and the Foundations of Software technolog

Computer-implemented land planning system and method with GIS integration

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Computer-implemented land planning system and method with automated parking area design tools

US10366180B2Algorithms and the Foundations of Software technolog

Thermal compression of atomic hydrogen on helium surface

We describe experiments with spin-polarized atomic hydrogen gas adsorbed on liquid $^{4}$He surface. The surface gas density is increased locally by thermal compression up to $5.5\times10^{12}$ cm$^{-2}$ at 110 mK. This corresponds to the onset of quantum degeneracy with the thermal de-Broglie wavelength being 1.5 times larger than the mean interatomic spacing. The atoms were detected directly with a 129 GHz electron-spin resonance spectrometer probing both the surface and the bulk gas. This, and the simultaneous measurement of the recombination power, allowed us to make accurate studies of the adsorption isotherm and the heat removal from the adsorbed hydrogen gas. From the data, we estimate the thermal contact between 2D hydrogen gas and phonons of the helium film. We analyze the limitations of the thermal compression method and the possibility to reach the superfluid transition in 2D hydrogen gas.Comment: 20 pages, 11 figure

The 3D Structure of N132D in the LMC: A Late-Stage Young Supernova Remnant

We have used the Wide Field Spectrograph (WiFeS) on the 2.3m telescope at Siding Spring Observatory to map the [O III] 5007{\AA} dynamics of the young oxygen-rich supernova remnant N132D in the Large Magellanic Cloud. From the resultant data cube, we have been able to reconstruct the full 3D structure of the system of [O III] filaments. The majority of the ejecta form a ring of ~12pc in diameter inclined at an angle of 25 degrees to the line of sight. We conclude that SNR N132D is approaching the end of the reverse shock phase before entering the fully thermalized Sedov phase of evolution. We speculate that the ring of oxygen-rich material comes from ejecta in the equatorial plane of a bipolar explosion, and that the overall shape of the SNR is strongly influenced by the pre-supernova mass loss from the progenitor star. We find tantalizing evidence of a polar jet associated with a very fast oxygen-rich knot, and clear evidence that the central star has interacted with one or more dense clouds in the surrounding ISM.Comment: Accepted for Publication in Astrophysics & Space Science, 18pp, 8 figure

Magnetic Field Amplification in Galaxy Clusters and its Simulation

We review the present theoretical and numerical understanding of magnetic field amplification in cosmic large-scale structure, on length scales of galaxy clusters and beyond. Structure formation drives compression and turbulence, which amplify tiny magnetic seed fields to the microGauss values that are observed in the intracluster medium. This process is intimately connected to the properties of turbulence and the microphysics of the intra-cluster medium. Additional roles are played by merger induced shocks that sweep through the intra-cluster medium and motions induced by sloshing cool cores. The accurate simulation of magnetic field amplification in clusters still poses a serious challenge for simulations of cosmological structure formation. We review the current literature on cosmological simulations that include magnetic fields and outline theoretical as well as numerical challenges.Comment: 60 pages, 19 Figure