1,580 research outputs found
Soliton dynamics in damped and forced Boussinesq equations
We investigate the dynamics of a lattice soliton on a monatomic chain in the
presence of damping and external forces. We consider Stokes and hydrodynamical
damping. In the quasi-continuum limit the discrete system leads to a damped and
forced Boussinesq equation. By using a multiple-scale perturbation expansion up
to second order in the framework of the quasi-continuum approach we derive a
general expression for the first-order velocity correction which improves
previous results. We compare the soliton position and shape predicted by the
theory with simulations carried out on the level of the monatomic chain system
as well as on the level of the quasi-continuum limit system. For this purpose
we restrict ourselves to specific examples, namely potentials with cubic and
quartic anharmonicities as well as the truncated Morse potential, without
taking into account external forces. For both types of damping we find a good
agreement with the numerical simulations both for the soliton position and for
the tail which appears at the rear of the soliton. Moreover we clarify why the
quasi-continuum approximation is better in the hydrodynamical damping case than
in the Stokes damping case
Optimal deployment of next-generation PON for high and ultra-high bandwidth demand scenarios in large urban areas
This paper proposes a techno-economic analysis of the optimal deployment of multiple PON networks with different technologies, including the newest next-generation standards, such as GPON, XGSPON, NG-PON2 and 50G-EPON, within a large urban area in Quito. On this zone, we simulated a population of around 20000 customers, distributed between two central offices. We assume that customers demand different bitrates considering present and future bitrate-demand scenarios. This analysis uses an algorithm called OTS (Optimal Topology Search) which employs a nested set of heuristics in order to find the optimal topology for the deployment of PON in large areas with many potential customers. Results obtained in this research describe an accurate projection of the optimal deployment cost and the most suitable PON technology for each bitrate demand scenario, taking into account not only the cost of the entire hardware, but leasing, labor-hours, pole-works and trenching/recapping-works
Magnus Expansion and Three-Neutrino Oscillations in Matter
We present a semi-analytical derivation of the survival probability of solar
neutrinos in the three generation scheme, based on the Magnus approximation of
the evolution operator of a three level system, and assuming a mass hierarchy
among neutrino mass eigenstates. We have used an exponential profile for the
solar electron density in our approximation. The different interesting density
regions that appear throughout the propagation are analyzed. Finally, some
comments on the allowed regions in the solar neutrino parameter space are
addressed.Comment: RevTex4 style, 5 pages including 5 figures. Presented at Mexican
School of Astrophysics 2002, Guanajuato, Mexico, 31 Jul - 7 Aug 2002. Final
version to appear in the Proceedings of IX Mexican Workshop on Particles and
Fields Physics Beyond the Standard Model, Colima Col. Mexico, November 17-22,
200
Modeling Teletraffic Arrivals by a Poisson Cluster Process
Modeling Teletraffic Arrivals by a Poisson Cluster Proces
Response of exact solutions of the nonlinear Schrodinger equation to small perturbations in a class of complex external potentials having supersymmetry and parity-time symmetry
We discuss the effect of small perturbation on nodeless solutions of the
nonlinear \Schrodinger\ equation in 1+1 dimensions in an external complex
potential derivable from a parity-time symmetric superpotential that was
considered earlier [Phys.~Rev.~E 92, 042901 (2015)]. In particular we consider
the nonlinear partial differential equation \{ \, \rmi \, \partial_t +
\partial_x^2 + g |\psi(x,t)|^2 - V^{+}(x) \, \} \, \psi(x,t) = 0, where
V^{+}(x) = \qty( -b^2 - m^2 + 1/4 ) \, \sech^2(x) - 2 i \, m \, b \, \sech(x)
\, \tanh(x) represents the complex potential. Here we study the perturbations
as a function of and using a variational approximation based on a
dissipation functional formalism. We compare the result of this variational
approach with direct numerical simulation of the equations. We find that the
variational approximation works quite well at small and moderate values of the
parameter which controls the strength of the imaginary part of the
potential. We also show that the dissipation functional formalism is equivalent
to the generalized traveling wave method for this type of dissipation.Comment: 18 pages, 6 figure
Electron neutrino tagging through tertiary lepton detection
We discuss an experimental technique aimed at tagging electron neutrinos in
multi-GeV artificial sources on an event-by-event basis. It exploits in a novel
manner calorimetric and tracking technologies developed in the framework of the
LHC experiments and of rare kaon decay searches. The setup is suited for
slow-extraction, moderate power beams and it is based on an instrumented decay
tunnel equipped with tagging units that intercept secondary and tertiary
leptons from the bulk of undecayed \pi^+ and protons. We show that the taggers
are able to reduce the \nue contamination originating from K_e3 decays by about
one order of magnitude. Only a limited suppression (~60%) is achieved for \nue
produced by the decay-in-flight of muons; for low beam powers, similar
performance as for K_e3 can be reached supplementing the tagging system with an
instrumented beam dump.Comment: 19 pages, 7 figures; minor changes, version to appear in EPJ
Direct-detection 25 Gb/s PON: PROs and CONs of digital signal processing at the transmitter side
We evaluate the performance of direct-detection 25 Gb/s Passive Optical Networks (PON) with adaptive equalization at the receiver side, comparing three transmitter schemes: two including digital signal processing (DSP), namely square-root raised-cosine pulse shaping and pre-emphasis, and the third one without any DSP pre-compensation. We show that DSP at transmitter side can provide a performance advantage only under strong bandwidth limitations and when considering feed-forward equalization (FFE) at the receiver. When including decision-feedback equalization (DFE), the use of pre-compensation at transmitter does not provide any advantage under linear transmission
Probing Sterile Neutrino Parameters with Double Chooz, Daya Bay and RENO
In this work, we present a realistic analysis of the potential of the
present-day reactor experiments Double Chooz, Daya Bay and RENO for probing the
existence of sterile neutrinos. We present exclusion regions for sterile
oscillation parameters for each of these experiments, using simulations with
realistic estimates of systematic errors and detector resolutions, and compare
the sterile parameter sensitivity regions we obtain with the existing bounds
from other reactor experiments. We find that these experimental set-ups give
significant bounds on the parameter \Theta_{ee} especially in the low sterile
oscillation region 0.01 < \Delta m_{41}^2 < 0.05 eV^2. These bounds can add to
our understanding of the sterile neutrino sector since there is still a tension
in the allowed regions from different experiments for sterile parameters.Comment: 12 pages, 5 figure
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