47,653 research outputs found
Thin film dynamics on a vertically rotating disk partially immersed in a liquid bath
The axisymmetric flow of a thin liquid film is considered for the problem of
a vertically rotating disk that is partially immersed in a liquid bath. A model
for the fully three-dimensional free-boundary problem of the rotating disk,
that drags a thin film out of the bath is set up. From this, a
dimension-reduced extended lubrication approximation that includes the meniscus
region is derived. This problem constitutes a generalization of the classic
drag-out and drag-in problem to the case of axisymmetric flow. The resulting
nonlinear fourth-order partial differential equation for the film profile is
solved numerically using a finite element scheme. For a range of parameters
steady states are found and compared to asymptotic solutions. Patterns of the
film profile, as a function of immersion depth and angular velocity are
discussed.Comment: 31 pages, 19 figures accepted: Applied Mathematical Modellin
Exploring the nucleon structure through GPDs and TDAs in hard exclusive processes
Generalized Parton Distributions (GPDs) offer a new way to access the quark
and gluon nucleon structure. We review recent progress in this domain,
emphasizing the need to supplement the experimental study of deeply virtual
Compton scattering by its crossed version, timelike Compton scattering. We also
describe the extension of the GPD concept to three quark operators and the
relevance of their nucleon to meson matrix elements, namely the transition
distribution amplitudes (TDAs) which factorize in backward meson
electroproduction and related processes. We discuss the main properties of the
TDAs. \Comment: 8 pages; to be published in the proceedings of the conference "PHOTON
2011, International Conference on the Structure and the Interactions of the
Photon ", Spa, Belgium, 22-27 Mai 201
New results in exclusive hard reactions
Generalized Parton Distributions offer a new way to access the quark and
gluon nucleon structure. We review recent progress in this domain, emphasizing
the need to supplement the experimental study of DVCS by its crossed version,
timelike Compton scattering (TCS), where data at high energy should appear
thanks to the study of ultraperipheral collisions at the LHC. This will open
the access to very low skewness quark and gluon GPDs. Our leading order
estimates show that the factorization scale dependence of the amplitudes is
quite high. This fact demands the understanding of higher order contributions
with the hope that they will stabilize this scale dependence. The magnitudes of
the NLO coefficient functions are not small and neither is the difference of
the coefficient functions appearing respectively in the DVCS and TCS
amplitudes. The conclusion is that extracting the universal GPDs from both TCS
and DVCS reactions requires much care. We also describe the extension of the
GPD concept to three quark operators and the relevance of their nucleon to
meson matrix elements, namely the transition distribution amplitudes (TDAs)
which factorize in hard exclusive pion electroproduction off a nucleon in the
backward region and baryon-antibaryon annihilation into a pion and a lepton
pair. We discuss the main properties of the TDAs.Comment: 4 pages, to be published in the proceedings of the 2011 Europhysics
Conference on High Energy Physics-HEP 2011, July 21-27, 2011, Grenoble,
Rhone-Alpes, Franc
Monolithically integrated active optical devices
Considerations relevant to the monolithic integration of optical detectors, lasers, and modulators with high speed amplifiers are discussed. Some design considerations for representative subsystems in the GaAs-AlGaAs and GaInAs-InP materials systems are described. Results of a detailed numerical design of an electro-optical birefringent filter for monolithic integration with a laser diode is described, and early experimental results on monolithic integration of broadband MESFET amplifiers with photoconductive detectors are reported
Stable Marriage with Multi-Modal Preferences
We introduce a generalized version of the famous Stable Marriage problem, now
based on multi-modal preference lists. The central twist herein is to allow
each agent to rank its potentially matching counterparts based on more than one
"evaluation mode" (e.g., more than one criterion); thus, each agent is equipped
with multiple preference lists, each ranking the counterparts in a possibly
different way. We introduce and study three natural concepts of stability,
investigate their mutual relations and focus on computational complexity
aspects with respect to computing stable matchings in these new scenarios.
Mostly encountering computational hardness (NP-hardness), we can also spot few
islands of tractability and make a surprising connection to the \textsc{Graph
Isomorphism} problem
How does Casimir energy fall? III. Inertial forces on vacuum energy
We have recently demonstrated that Casimir energy due to parallel plates,
including its divergent parts, falls like conventional mass in a weak
gravitational field. The divergent parts were suitably interpreted as
renormalizing the bare masses of the plates. Here we corroborate our result
regarding the inertial nature of Casimir energy by calculating the centripetal
force on a Casimir apparatus rotating with constant angular speed. We show that
the centripetal force is independent of the orientation of the Casimir
apparatus in a frame whose origin is at the center of inertia of the apparatus.Comment: 8 pages, 2 figures, contribution to QFEXT07 proceeding
Two-lane traffic rules for cellular automata: A systematic approach
Microscopic modeling of multi-lane traffic is usually done by applying
heuristic lane changing rules, and often with unsatisfying results. Recently, a
cellular automaton model for two-lane traffic was able to overcome some of
these problems and to produce a correct density inversion at densities somewhat
below the maximum flow density. In this paper, we summarize different
approaches to lane changing and their results, and propose a general scheme,
according to which realistic lane changing rules can be developed. We test this
scheme by applying it to several different lane changing rules, which, in spite
of their differences, generate similar and realistic results. We thus conclude
that, for producing realistic results, the logical structure of the lane
changing rules, as proposed here, is at least as important as the microscopic
details of the rules
Identification of soybean (Glycine max (L.) Merrill) cultivars using rapid laboratory techniques
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