33,225 research outputs found
A frictional Cosserat model for the flow of granular materials through a vertical channel
A rigid-plastic Cosserat model has been used to study dense, fully developed
flow of granular materials through a vertical channel. Frictional models based
on the classical continuum do not predict the occurrence of shear layers, at
variance with experimental observations. This feature has been attributed to
the absence of a material length scale in their constitutive equations. The
present model incorporates such a material length scale by treating the
granular material as a Cosserat continuum. Thus localised couple stresses exist
and the stress tensor is asymmetric. The velocity profiles predicted by the
model are in close agreement with available experimental data. The predicted
dependence of the shear layer thickness on the width of the channel is in
reasonable agreement with data. In the limit of the ratio of the particle
diameter to the half-width of the channel being small, the model predicts that
the shear layer thickness scaled by the particle diameter grows.Comment: 17 pages, 12 PostScript figures, uses AmsLaTeX, psfrag and natbib.
Accepted for publication in Acta Mechanic
Transport in Luttinger Liquids
We give a brief introduction to Luttinger liquids and to the phenomena of
electronic transport or conductance in quantum wires. We explain why the
subject of transport in Luttinger liquids is relevant and fascinating and
review some important results on tunneling through barriers in a
one-dimensional quantum wire and the phenomena of persistent currents in
mesoscopic rings. We give a brief description of our own work on transport
through doubly-crossed Luttinger liquids and transport in the Schulz-Shastry
exactly solvable Luttinger-like model.Comment: Latex file, 15 pages, four eps figure
Some experiences with the viscous-inviscid interaction approach
Methods for simulating compressible viscous flow using the viscid-inviscid interaction approach are described. The formulations presented range from the more familiar full-potential/boundary-layer interaction schemes to a method for coupling Euler/Navier-Stokes and boundary-layer algorithms. An effort is made to describe the advantages and disadvantages of each formulation. Sample results are presented which illustrate the applicability of the methods
Hindu-Christian Dialogue: A Hindu Perspective
I wish to express my deep appreciation and thanks to Professor Harold Coward for inviting me to contribute an article on Hindu-Christian Dialogue: A Hindu Perspective for his Bulletin. This theme has engaged my interest for the last three decades, and I am glad at the opportunity to express my thoughts on this very relevant and significant subject at the dawn of the 21st century
Research and development of a high capacity, nonaqueous secondary battery Final report, Oct. 1964 - Dec. 1965
High capacity nonaqueous secondary batter
Research and development of a capacity nonaqueous secondary battery Fourth quarterly report, Jul. - Sep. 1965
High capacity nonaqueous secondary battery development - lithium deposition and cycling, ionic solvation, cathode construction and discharge efficiency, and solvent purificatio
Brillouin Scattering Studies of La_{0.77}Ca_{0.23}MnO_3 Across Metal-Insulator Transition
Temperature-dependent Brillouin scattering studies have been carried out on
La_{0.77}Ca_{0.23}MnO_3 across the paramagnetic insulator - ferromagnetic metal
(I-M) transition. The spectra show a surface Rayleigh wave (SRW) and a high
velocity pseudo surface acoustic wave (HVPSAW) besides bulk acoustic waves
(BAW). The Brillouin shifts associated with SRW and HVPSAW show blue-shifts,
where as the frequencies of the BAW decrease below the I-M transition
temperature (T_C) of 230 K. These results can be understood based on the
temperature dependence of the elastic constants. We also observe a central peak
whose width is maximum at T_C.Comment: 7 pages, 8 figure
Long-term Perspectives for Carbon Capture in Power Plants: Scenarios for the 21st Century
The report analyzes the role of fossil-fired power plants equipped with carbon capture systems in long-term scenarios of the global energy system representing technological change as an endogenous process. Within this framework the impacts of a technology policy is illustrated that requires over time an increasing fraction of fossil-fired power generation to incorporate carbon capture technologies. In particular, we examine the potential costs and the contribution that such a policy could offer in reducing energy-related carbon dioxide emissions and highlight some of the technologies that may play a role in doing so. The analysis is carried out with the global energysystems optimization MESSAGE model (Messner and Strubegger 1995) considering endogenous technology learning for fossil power plants and the corresponding carbon capture technologies, such that they experience cost reductions as a function of accumulated capacity installations. The report describes two baseline scenarios: (1) including learning for fossil power plants and (2) the other with no learning. In addition, the analysis examines three cases that are based on a technology policy that enforces an increasing share of fossil fuel power plants with carbon capture, distinguishing between future worlds assuming: (1) no learning for fossil systems, (2) learning just for the carbon capture component, and (3) full learning for the reference plants as well as for the carbon capture systems.
The analysis shows that the introduction of a policy for carbon capture and storage would lead to considerable reductions in carbon emissions in the electricity sector and major changes in the power generation mix. Technologies are chosen, that provide the most cost-effective combination between electricity generation and carbon capture, fostering the penetration of advanced fossil technologies. In particular, coal gasification systems such as, IGCC power plants and high temperature fuel cells, and in addition gas-fired combined cycle power plants appear as the most attractive fossil-fired electricity generation options
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