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Optimal Policy Derivation for Transmission Duty-Cycle Constrained LPWAN
Low-power wide-area network (LPWAN) technologies enable Internet of Things (IoT) devices to efficiently and robustly communicate over long distances, thus making them especially suited for industrial environments. However, the stringent regulations on the usage of certain industrial, scientific, and medical bands in many countries in which LPWAN operate limit the amount of time IoT motes can occupy the shared bands. This is particularly challenging in industrial scenarios, where not being able to report some detected events might result in the failure of critical assets. To alleviate this, and by mathematically modeling LPWAN-based IoT motes, we have derived optimal transmission policies that maximize the number of reported events (prioritized by their importance) while still complying with current regulations. The proposed solution has been customized for two widely known LPWAN technologies: 1) LoRa and 2) Sigfox. Analytical results reveal that our solution is feasible and performs remarkably close to the theoretical limit for a wide range of network activity patterns
Hawking-like emission in kink-soliton escape from a potential well.
The escape of solitons over a potential barrier is analysed within the framework of a nonlinear Klein–Gordon equation. It is shown that the creation of a kink–antikink pair near the barrier through an internal mode instability can be followed by escape of the kink in a process analogous to Hawking radiation. These results have important implications in a wider context, including stochastic resonance and ratchet systems, which are also discussed
Radiative corrections to from three generations of Majorana neutrinos and sneutrinos
In this work we study the radiative corrections to the mass of the lightest
Higgs boson of the MSSM from three generations of Majorana neutrinos and
sneutrinos. The spectrum of the MSSM is augmented by three right handed
neutrinos and their supersymmetric partners. A seesaw mechanism of type I is
used to generate the physical neutrino masses and oscillations that we require
to be in agreement with present neutrino data. We present a full one-loop
computation of these Higgs mass corrections, and analyze in full detail their
numerical size in terms of both the MSSM and the new (s)neutrino parameters. A
critical discussion on the different possible renormalization schemes and their
implications is included.Comment: 42 pages, 39 figures, 1 appendix, version published in AHE
Study of star-forming galaxies in SDSS up to redshift 0.4: I. Metallicity evolution
The chemical composition of the gas in galaxies versus cosmic time provides a
very important tool for understanding galaxy evolution. Although there are many
studies at high redshift, they are rather scarce at lower redshifts. However,
low redshift studies can provide important clues about the evolution of
galaxies, furnishing the required link between local and high redshift
universe. In this work we focus on the metallicity of the gas of star-forming
galaxies at low redshift, looking for signs of chemical evolution.
To analyze the metallicity contents star-forming galaxies of similar
luminosities and masses at different redshifts. With this purpose, we present a
study of the metallicity of relatively massive (log(M_star/M_sun)>10.5) star
forming galaxies from SDSS--DR5 (Sloan Digital Sky Survey--Data Release 5),
using different redshift intervals from 0.04 to 0.4.
We used data processed with the STARLIGHT spectral synthesis code, correcting
the fluxes for dust extinction, estimating metallicities using the R_23 method,
and segregating the samples with respect to the value of the
[NII]6583/[OII]3727 line ratio in order to break the R_23 degeneracy selecting
the upper branch. We analyze the luminosity and mass-metallicity relations, and
the effect of the Sloan fiber diameter looking for possible biases.
By dividing our redshift samples in intervals of similar magnitude and
comparing them, significant signs of metallicity evolution are found.
Metallicity correlates inversely with redshift: from redshift 0 to 0.4 a
decrement of ~0.1 dex in 12+log(O/H) is found.Comment: 11 pages, 9 figures, Accepted for publication in A&
The INTEGRAL-OMC Scientific Archive
The Optical Monitoring Camera (OMC) on-board the INTEGRAL satellite has, as
one of its scientific goals, the observation of a large number of variable
sources previously selected. After almost 6 years of operations, OMC has
monitored more than 100 000 sources of scientific interest. In this
contribution we present the OMC Scientific Archive
(http://sdc.laeff.inta.es/omc/) which has been developed to provide the
astronomical community with a quick access to the light curves generated by
this instrument.We describe the main characteristics of this archive, as well
as important aspects for the users: object types, temporal sampling of light
curves and photometric accuracy.Comment: 4 pages, 5 figures. "Highlights of Spanish Astrophysics V"
Proceedings of the VIII Scientific Meeting of the Spanish Astronomical
Society (SEA) held in Santander, July 7-11, 200
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