13,208 research outputs found
Effect of external electric field on the charge density waves in one dimensional Hubbard superlattices
We have studied the ground state of the one dimensional Hubbard superlattice
structures with different unit cell sizes in the presence of electric field.
Self consistent Hartree-Fock approximation calculation is done in the weak to
intermediate interaction regime. Studying the charge gap at the Fermi level and
the charge density structure factor, we get an idea how the charge modulation
on the superlattice is governed by the competition between the electronic
correlation and the external electric field.Comment: 6 pages, 8 figures. accepted in Journal of Physics: Condensed Matte
Flow properties of driven-diffusive lattice gases: theory and computer simulation
We develop n-cluster mean-field theories (0 < n < 5) for calculating the flow
properties of the non-equilibrium steady-states of the Katz-Lebowitz-Spohn
model of the driven diffusive lattice gas, with attractive and repulsive
inter-particle interactions, in both one and two dimensions for arbitrary
particle densities, temperature as well as the driving field. We compare our
theoretical results with the corresponding numerical data we have obtained from
the computer simulations to demonstrate the level of accuracy of our
theoretical predictions. We also compare our results with those for some other
prototype models, notably particle-hopping models of vehicular traffic, to
demonstrate the novel qualitative features we have observed in the
Katz-Lebowitz-Spohn model, emphasizing, in particular, the consequences of
repulsive inter-particle interactions.Comment: 12 RevTex page
CFD Modeling of Globe Valves for Oxygen Application
Components used in high-pressure, high-temperature, flowing oxygen are susceptible to ignition and combustion in presence of restriction or when particles impact these restriction. The valves in any systems are the common flow restrictors, hence, the design and analyses of valves are most critical tasks. The flow of oxygen through valves distinguishes itself by accentuating auto-ignition and consequent flame propagation in metals and non-metals, apart from other usual characteristics present with gases/liquids. The combination of ignition resistance, proper and reliable performance and fabrication economy marks the specification of material and design of valves in oxygen-enriched environment. The analyses have been performed by applying the commercial computational fluid dynamics (CFD) code, FLUENT, to obtain the solution of the two-dimensional turbulent flow field through a globe valve for its different openings in the GOX environment. The flow control valves in high velocity oxygen systems for different openings are simulated for turbulence and eddy dissipation. The influence of pressure, flow rate and opening of the valve on the rise in temperature and eddy dissipation rate is also obtained for compressible flow range. The simulation for turbulence is done by k- and k- turbulence models and the results have been compared
Hybrid LSTM and Encoder-Decoder Architecture for Detection of Image Forgeries
With advanced image journaling tools, one can easily alter the semantic
meaning of an image by exploiting certain manipulation techniques such as
copy-clone, object splicing, and removal, which mislead the viewers. In
contrast, the identification of these manipulations becomes a very challenging
task as manipulated regions are not visually apparent. This paper proposes a
high-confidence manipulation localization architecture which utilizes
resampling features, Long-Short Term Memory (LSTM) cells, and encoder-decoder
network to segment out manipulated regions from non-manipulated ones.
Resampling features are used to capture artifacts like JPEG quality loss,
upsampling, downsampling, rotation, and shearing. The proposed network exploits
larger receptive fields (spatial maps) and frequency domain correlation to
analyze the discriminative characteristics between manipulated and
non-manipulated regions by incorporating encoder and LSTM network. Finally,
decoder network learns the mapping from low-resolution feature maps to
pixel-wise predictions for image tamper localization. With predicted mask
provided by final layer (softmax) of the proposed architecture, end-to-end
training is performed to learn the network parameters through back-propagation
using ground-truth masks. Furthermore, a large image splicing dataset is
introduced to guide the training process. The proposed method is capable of
localizing image manipulations at pixel level with high precision, which is
demonstrated through rigorous experimentation on three diverse datasets
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