98,112 research outputs found
On some generalized ageing orderings
Some partial orderings which compare probability distributions with the expo-
nential distribution, are found to be very useful to understand the phenomenon
of ageing. Here, we introduce some new generalized partial orderings which de-
scribe the same kind of characterization of some generalized ageing classes. We
give some equivalent conditions for each of the orderings. Inter-relations
among the generalized orderings have also been discussed
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Turbulent convective heat transfer and pressure drop of dilute CuO (copper oxide) - water nanofluid Inside a circular tube
This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.Turbulent forced convective heat transfer and pressure drop of 0.01 vol.% CuO-water nanofluid was assessed experimentally. The nanofluids were made flow into a heated horizontal tube under uniform constant heat flux within Reynolds number range of 11,500 to 32,000. The first objective is to know how close traditional correlation/formula for, both, heat transfer and pressure drop can predict nanofluid’s heat transfer and pressure drop. The second is to know how nanofluid’s convective heat transfer and pressure drop are compared to those of its base fluid; in this case water. The results showed that the abovementioned characteristics of the nanofluid can be predicted by the traditional correlation available. It is also found that the nanofluid’s Nusselt number and friction factor, which represent the heat transfer rate and pressure drop, respectively, are close to those of water. Hence, there is no anomaly due to the dispersed nanoparticles within the water.KACST (King Abdulaziz City for Science and Technology
Topological Confinement and Superconductivity
We derive a Kondo Lattice model with a correlated conduction band from a
two-band Hubbard Hamiltonian. This mapping allows us to describe the emergence
of a robust pairing mechanism in a model that only contains repulsive
interactions. The mechanism is due to topological confinement and results from
the interplay between antiferromagnetism and delocalization. By using
Density-Matrix-Renormalization-Group (DMRG), we demonstrate that this mechanism
leads to dominant superconducting correlations in a 1D-system.Comment: 4 pages, 4 figure
Transport properties of strongly correlated electrons in quantum dots using a simple circuit model
Numerical calculations are shown to reproduce the main results of recent
experiments involving nonlocal spin control in nanostructures (N. J. Craig et
al., Science 304, 565 (2004)). In particular, the splitting of the
zero-bias-peak discovered experimentally is clearly observed in our studies. To
understand these results, a simple "circuit model" is introduced and shown to
provide a good qualitative description of the experiments. The main idea is
that the splitting originates in a Fano anti-resonance, which is caused by
having one quantum dot side-connected in relation to the current's path. This
scenario provides an explanation of Craig et al.'s results that is alternative
to the RKKY proposal, which is here also addressed.Comment: 5 pages, 5 figure
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