164,716 research outputs found
Efficient Regularization of Squared Curvature
Curvature has received increased attention as an important alternative to
length based regularization in computer vision. In contrast to length, it
preserves elongated structures and fine details. Existing approaches are either
inefficient, or have low angular resolution and yield results with strong block
artifacts. We derive a new model for computing squared curvature based on
integral geometry. The model counts responses of straight line triple cliques.
The corresponding energy decomposes into submodular and supermodular pairwise
potentials. We show that this energy can be efficiently minimized even for high
angular resolutions using the trust region framework. Our results confirm that
we obtain accurate and visually pleasing solutions without strong artifacts at
reasonable run times.Comment: 8 pages, 12 figures, to appear at IEEE conference on Computer Vision
and Pattern Recognition (CVPR), June 201
Customer-engineer relationship management for converged ICT service companies
Thanks to the advent of converged communications services (often referred to as ‘triple play’), the next generation Service Engineer will need radically different skills, processes and tools from today’s counterpart. Why? in order to meet the challenges of installing and maintaining services based on multi-vendor software and hardware components in an IP-based network environment. The converged services environment is likely to be ‘smart’ and support flexible and dynamic interoperability between appliances and computing devices. These radical changes in the working environment will inevitably force managers to rethink the role of Service Engineers in relation to customer relationship management. This paper aims to identify requirements for an information system to support converged communications service engineers with regard to customer-engineer relationship management. Furthermore, an architecture for such a system is proposed and how it meets these requirements is discussed
Top-quark mass effects in double and triple Higgs production in gluon-gluon fusion at NLO
The observation of double and triple scalar boson production at hadron
colliders could provide key information on the Higgs self couplings and the
potential. As for single Higgs production the largest rates for multiple Higgs
production come from gluon-gluon fusion processes mediated by a top-quark loop.
However, at variance with single Higgs production, top-quark mass and width
effects from the loops cannot be neglected. Computations including the exact
top-quark mass dependence are only available at the leading order, and
currently predictions at higher orders are obtained by means of approximations
based on the Higgs-gluon effective field theory (HEFT). In this work we present
a reweighting technique that, starting from events obtained via the MC@NLO
method in the HEFT, allows to exactly include the top-quark mass and width
effects coming from one- and two-loop amplitudes. We describe our approach and
apply it to double Higgs production at NLO in QCD, computing the needed
one-loop amplitudes and using approximations for the unknown two-loop ones. The
results are compared to other approaches used in the literature, arguing that
they provide more accurate predictions for distributions and for total rates as
well. As a novel application of our procedure we present predictions at NLO in
QCD for triple Higgs production at hadron colliders.Comment: 24 pages, 8 figure
Coherent electron transport by adiabatic passage in an imperfect donor chain
Coherent Tunneling Adiabatic Passage (CTAP) has been proposed as a long-range
physical qubit transport mechanism in solid-state quantum computing
architectures. Although the mechanism can be implemented in either a chain of
quantum dots or donors, a 1D chain of donors in Si is of particular interest
due to the natural confining potential of donors that can in principle help
reduce the gate densities in solid-state quantum computing architectures. Using
detailed atomistic modeling, we investigate CTAP in a more realistic triple
donor system in the presence of inevitable fabrication imperfections. In
particular, we investigate how an adiabatic pathway for CTAP is affected by
donor misplacements, and propose schemes to correct for such errors. We also
investigate the sensitivity of the adiabatic path to gate voltage fluctuations.
The tight-binding based atomistic treatment of straggle used here may benefit
understanding of other donor nanostructures, such as donor-based charge and
spin qubits. Finally, we derive an effective 3 \times 3 model of CTAP that
accurately resembles the voltage tuned lowest energy states of the
multi-million atom tight-binding simulations, and provides a translation
between intensive atomistic Hamiltonians and simplified effective Hamiltonians
while retaining the relevant atomic-scale information. This method can help
characterize multi-donor experimental structures quickly and accurately even in
the presence of imperfections, overcoming some of the numeric intractabilities
of finding optimal eigenstates for non-ideal donor placements.Comment: 9 pages, 8 figure
Geometric Low-Energy Effective Action in a Doubled Spacetime
The ten-dimensional supergravity theory is a geometric low-energy effective
theory and the equations of motion for its fields can be obtained from string
theory by computing functions. With compact dimensions, we can add
to it an geometric structure and construct the
supergravity theory inspired by double field theory through the use of a
suitable commutative star product. The latter implements the weak constraint of
the double field theory on its fields and gauge parameters in order to have a
closed gauge symmetry algebra. The consistency of the action here proposed is
based on the orthogonality of the momenta associated with fields in their
triple star products in the cubic terms defined for . This orthogonality
holds also for an arbitrary number of star products of fields for .
Finally, we extend our analysis to the double sigma model, non-commutative
geometry and open string theory.Comment: 27 pages, minor changes, references adde
Multilevel Monte Carlo simulation for Levy processes based on the Wiener-Hopf factorisation
In Kuznetsov et al. (2011) a new Monte Carlo simulation technique was
introduced for a large family of Levy processes that is based on the
Wiener-Hopf decomposition. We pursue this idea further by combining their
technique with the recently introduced multilevel Monte Carlo methodology.
Moreover, we provide here for the first time a theoretical analysis of the new
Monte Carlo simulation technique in Kuznetsov et al. (2011) and of its
multilevel variant for computing expectations of functions depending on the
historical trajectory of a Levy process. We derive rates of convergence for
both methods and show that they are uniform with respect to the "jump activity"
(e.g. characterised by the Blumenthal-Getoor index). We also present a modified
version of the algorithm in Kuznetsov et al. (2011) which combined with the
multilevel methodology obtains the optimal rate of convergence for general Levy
processes and Lipschitz functionals. This final result is only a theoretical
one at present, since it requires independent sampling from a triple of
distributions which is currently only possible for a limited number of
processes
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