5,204 research outputs found
Ignition and Front Propagation in Polymer Electrolyte Membrane Fuel Cells
Water produced in a Polymer Electrolyte Membrane (PEM) fuel cell enhances
membrane proton conductivity; this positive feedback loop can lead to current
ignition. Using a segmented anode fuel cell we study the effect of gas phase
convection and membrane diffusion of water on the spatiotemporal nonlinear
dynamics - localized ignition and front propagation - in the cell. Co-current
gas flow causes ignition at the cell outlet, and membrane diffusion causes the
front to slowly propagate to the inlet; counter-current flow causes ignition in
the interior of the cell, with the fronts subsequently spreading towards both
inlets. These instabilities critically affect fuel cell performance
Unsupervised Diverse Colorization via Generative Adversarial Networks
Colorization of grayscale images has been a hot topic in computer vision.
Previous research mainly focuses on producing a colored image to match the
original one. However, since many colors share the same gray value, an input
grayscale image could be diversely colored while maintaining its reality. In
this paper, we design a novel solution for unsupervised diverse colorization.
Specifically, we leverage conditional generative adversarial networks to model
the distribution of real-world item colors, in which we develop a fully
convolutional generator with multi-layer noise to enhance diversity, with
multi-layer condition concatenation to maintain reality, and with stride 1 to
keep spatial information. With such a novel network architecture, the model
yields highly competitive performance on the open LSUN bedroom dataset. The
Turing test of 80 humans further indicates our generated color schemes are
highly convincible
A high flux source of cold strontium atoms
We describe an experimental apparatus capable of achieving a high loading
rate of strontium atoms in a magneto-optical trap operating in a high vacuum
environment. A key innovation of this setup is a two dimensional
magneto-optical trap deflector located after a Zeeman slower. We find a loading
rate of 6x10^9/s whereas the lifetime of the magnetically trapped atoms in the
3P2 state is 54s.Comment: 12 pages, 16 figure
Modeling Coastal and Estuarine Processes for Coastal Flood Management and Erosion Protection against Storms
Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv
Continuum Superpartners
In an exact conformal theory there is no particle. The excitations have
continuum spectra and are called "unparticles" by Georgi. We consider
supersymmetric extensions of the Standard Model with approximate conformal
sectors. The conformal symmetry is softly broken in the infrared which
generates a gap. However, the spectrum can still have a continuum above the gap
if there is no confinement. Using the AdS/CFT correspondence this can be
achieved with a soft wall in the warped extra dimension. When supersymmetry is
broken the superpartners of the Standard Model particles may simply be a
continuum above gap. The collider signals can be quite different from the
standard supersymmetric scenarios and the experimental searches for the
continuum superpartners can be very challenging.Comment: 15 pages, 5 figures, talk at SCGT09 Workshop, Nagoya, Japan, 8-11
Dec, 200
Field-angle Dependence of the Zero-Energy Density of States in the Unconventional Heavy-Fermion Superconductor CeCoIn5
Field-angle dependent specific heat measurement has been done on the
heavy-fermion superconductor CeCoIn5 down to ~ 0.29 K, in a magnetic field
rotating in the tetragonal c-plane. A clear fourfold angular oscillation is
observed in the specific heat with the minima (maxima) occurring along the
[100] ([110]) directions. Oscillation persists down to low fields H << Hc2,
thus directly proving the existence of gap nodes. The results indicate that the
superconducting gap symmetry is most probably of dxy type.Comment: 8 pages, 3 figures, to be published in J. Phys. Condens. Matte
Probing Lepton Flavor Violation at Future Colliders
Supersymmetric theories with significant lepton flavor violation have
and nearly degenerate. In this case, pair production
of and at LEPII and at
the Next Linear Collider leads to the phenomenon of slepton oscillations, which
is analogous to neutrino oscillations. The reach in and gives a probe of lepton flavor violation which is significantly more
powerful than the current bounds from rare processes, such as . Polarizable beams and the mode at the NLC are found to
be promising options.Comment: 10 pages, 3 figures, RevTeX, minor corrections, published versio
Doping and temperature dependence of electron spectrum and quasiparticle dispersion in doped bilayer cuprates
Within the t-t'-J model, the electron spectrum and quasiparticle dispersion
in doped bilayer cuprates in the normal state are discussed by considering the
bilayer interaction. It is shown that the bilayer interaction splits the
electron spectrum of doped bilayer cuprates into the bonding and antibonding
components around the point. The differentiation between the bonding
and antibonding components is essential, which leads to two main flat bands
around the point below the Fermi energy. In analogy to the doped
single layer cuprates, the lowest energy states in doped bilayer cuprates are
located at the point. Our results also show that the striking
behavior of the electronic structure in doped bilayer cuprates is intriguingly
related to the bilayer interaction together with strong coupling between the
electron quasiparticles and collective magnetic excitations.Comment: 9 pages, 4 figures, updated references, added figures and
discussions, accepted for publication in Phys. Rev.
Composite-fermion crystallites in quantum dots
The correlations in the ground state of interacting electrons in a
two-dimensional quantum dot in a high magnetic field are known to undergo a
qualitative change from liquid-like to crystal-like as the total angular
momentum becomes large. We show that the composite-fermion theory provides an
excellent account of the states in both regimes. The quantum mechanical
formation of composite fermions with a large number of attached vortices
automatically generates omposite fermion crystallites in finite quantum dots.Comment: 5 pages, 3 figure
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