1,944 research outputs found
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
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
Building C(sp(3)) Molecular Complexity on 2,2 '-Bipyridine and 1,10-Phenanthroline in Rhenium Tricarbonyl Complexes
The reactions of [Re(N-N)(CO)(3)(PMe3)]OTf (N-N=2,2 '-bipyridine, bipy; 1,10-phenanthroline, phen) compounds with tBuLi and with LiHBEt3 have been explored. Addition to the N-N chelate took place with different site-selectivity depending on both chelate and nucleophile. Thus, with tBuLi, an unprecedented addition to C5 of bipy, a regiochemistry not accessible for free bipy, was obtained, whereas coordinated phen underwent tBuLi addition to C2 and C4. Remarkably, when LiHBEt3 reacted with [Re(bipy)(CO)(3)(PMe3)]OTf, hydride addition to the 4 and 6 positions of bipy triggered an intermolecular cyclodimerization of two dearomatized pyridyl rings. In contrast, hydride addition to the phen analog resulted in partial reduction of one pyridine ring. The resulting neutral Re-I products showed a varied reactivity with HOTf and with MeOTf to yield cationic complexes. These strategies rendered access to Re-I complexes containing bipy- and phen-derived chelates with several C(sp(3)) centers
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
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