1,013 research outputs found
Geopolymer Bricks Using Iron Ore Tailings, Slag Sand, Ground Granular Blast Furnace Slag and Fly Ash
World is pound with million tonnes of industrial wastes such as ground granulated blast furnace slag (GGBS), flyash and mine tailings as a various industrial waste. The best way to make use of these wastes is to incorporate these materials as structural elements, which in turn minimizes the carbon foot print. In this contest, this study focuses on using iron ore tailings and slag sand as a replacement for clay or natural sand for the production of stabilized geopolymer blocks. Also, in this study geopolymer is used as a stabilizer instead of cement. Development of geopolymer binder based bricks using flyash and ground granulated blast furnace slag has been carried out in this research. The study includes mechanical properties of the geopolymer bricks. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solution have been used as alkaline activators. The ratio of alkaline liquid to aluminosilicate solid ratio and percentage of binder had major influence on the strength of brick. The bricks were casted and cured at ambient temperature. The compressive strength was carried out at 7, 14 and 28 days
Bond-orientational ordering and shear rigidity in modulated colloidal liquids
From Landau-Alexander-McTague theory and Monte-Carlo simulation results we
show that the modulated liquid obtained by subjecting a colloidal system to a
periodic laser modulation has long range bond-orientational order and non-zero
shear rigidity. From infinite field simulation results we show that in the
modulated liquid phase, the translational order parameter correlation function
decays to zero exponentially while the correlation function for the
bond-orientational order saturates to a finite value at large distances.Comment: 8 pages, elsart documentclass, to be published in Physica A as part
of proceedings for Stat-Phys 3, Calcutt
The Liquid-Gas Phase Transitions in a Multicomponent Nuclear System with Coulomb and Surface Effects
The liquid-gas phase transition is studied in a multi-component nuclear
system using a local Skyrme interaction with Coulomb and surface effects. Some
features are qualitatively the same as the results of Muller and Serot which
uses relativistic mean field without Coulomb and surface effects. Surface
tension brings the coexistance binodal surface to lower pressure. The Coulomb
interaction makes the binodal surface smaller and cause another pair of binodal
points at low pressure and large proton fraction with less protons in liquid
phase and more protons in gas phase.Comment: 20 pages including 7 postscript figure
Solidification behavior of intensively sheared hypoeutectic Al-Si alloy liquid
The official published version of this article can be found at the link below.The effect of the processing temperature on the microstructural and mechanical properties of Al-Si (hypoeutectic) alloy solidified from intensively sheared liquid metal has been investigated systematically. Intensive shearing gives a significant refinement in grain size and intermetallic particle size. It also is observed that the morphology of intermetallics, defect bands, and microscopic defects in high-pressure die cast components are affected by intensive shearing the liquid metal. We attempt to discuss the possible mechanism for these effects.Funded by the EPSRC
Improved fisheries productivity and management in tropical reservoirs
âImproved fisheries productivity and management in tropical reservoirsâ
The objective of the project was to contribute to the current research on reservoirs enhancement
fisheries in tropical countries through the implementation of a series of action-research activities
implemented in two small reservoirs in the Indo-Gangetic basin in India, and two very large
reservoirs in Africa, the Lake Nasser (Egypt), and the Volta Lake (Ghana). Socio-institutional
analyses were also conducted in these reservoirs to improve our knowledge regarding some of the
main social processes that influence reservoir productivity. Overall the results of the project stress
that while the natural biophysical constraints of the reservoirs are important in defining the
ecological production processes, it is the socio-economic settings characterizing the
community/societies around the reservoirs that eventually shape the human production
enhancement possibilities
Effect of melt conditioning on heat treatment and mechanical properties of AZ31 alloy strips produced by twin roll casting
In the present investigation, magnesium strips were produced by twin roll casting (TRC) and melt conditioned twin roll casting (MC-TRC) processes. Detailed optical microscopy studies were carried out on as-cast and homogenized TRC and MC-TRC strips. The results showed uniform, fine and equiaxed grain structure was observed for MC-TRC samples in as-cast condition. Whereas, coarse columnar grains with centreline segregation were observed in the case of as-cast TRC samples. The solidification mechanisms for TRC and MC-TRC have been found completely divergent. The homogenized TRC and MC-TRC samples were subjected to tensile test at elevated temperature (250-400 °C). At 250 °C, MC-TRC sample showed significant improvement in strength and ductility. However, at higher temperatures the tensile properties were almost comparable, despite of TRC samples having larger grains compared to MC-TRC samples. The mechanism of deformation has been explained by detailed fractures surface and sub-surface analysis carried out by scanning electron and optical microscopy. Homogenized MC-TRC samples were formed (hot stamping) into engineering component without any trace of crack on its surface. Whereas, TRC samples cracked in several places during hot stamping process.EPSRC â LiME, UK and Towards Affordable, Closed-Loop Recyclable Future Low Carbon Vehicle Structures â TARF-LCV(EP/I038616/1), Department of Mechanical Engineering, Imperial College London, UK, Mr. Steve Cook, Mr. Peter Lloyd, Mr. Graham Mitchell and Mr. Carmelo and BCAST, Brunel University London
Kalb-Ramond excitations in a thick-brane scenario with dilaton
We compute the full spectrum and eigenstates of the Kalb-Ramond field in a
warped non-compact Randall-Sundrum -type five-dimensional spacetime in which
the ordinary four-dimensional braneworld is represented by a sine-Gordon
soliton. This 3-brane solution is fully consistent with both the warped
gravitational field and bulk dilaton configurations. In such a background we
embed a bulk antisymmetric tensor field and obtain, after reduction, an
infinite tower of normalizable Kaluza-Klein massive components along with a
zero-mode. The low lying mass eigenstates of the Kalb-Ramond field may be
related to the axion pseudoscalar. This yields phenomenological implications on
the space of parameters, particularly on the dilaton coupling constant. Both
analytical and numerical results are given.Comment: 10 pages, 13 figures, and 2 tables. Final version to appear in The
European Physical Journal
The outer halos of elliptical galaxies
Recent progress is summarized on the determination of the density
distributions of stars and dark matter, stellar kinematics, and stellar
population properties, in the extended, low surface brightness halo regions of
elliptical galaxies. With integral field absorption spectroscopy and with
planetary nebulae as tracers, velocity dispersion and rotation profiles have
been followed to ~4 and ~5-8 effective radii, respectively, and in M87 to the
outer edge at ~150 kpc. The results are generally consistent with the known
dichotomy of elliptical galaxy types, but some galaxies show more complex
rotation profiles in their halos and there is a higher incidence of
misalignments, indicating triaxiality. Dynamical models have shown a range of
slopes for the total mass profiles, and that the inner dark matter densities in
ellipticals are higher than in spiral galaxies, indicating earlier assembly
redshifts. Analysis of the hot X-ray emitting gas in X-ray bright ellipticals
and comparison with dynamical mass determinations indicates that non-thermal
components to the pressure may be important in the inner ~10 kpc, and that the
properties of these systems are closely related to their group environments.
First results on the outer halo stellar population properties do not yet give a
clear picture. In the halo of one bright galaxy, lower [alpha/Fe] abundances
indicate longer star formation histories pointing towards late accretion of the
halo. This is consistent with independent evidence for on-going accretion, and
suggests a connection to the observed size evolution of elliptical galaxies
with redshift.Comment: 8 pages. Invited review to appear in the proceedings of "Galaxies and
their Masks" eds. Block, D.L., Freeman, K.C. & Puerari, I., 2010, Springer
(New York
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