4,058 research outputs found
A new species of Monocondylaeinae from the Amazon basin, and some considerations on this subfamily in the hydrographic systems of South America
In this work Tamsiella amazonica nov. sp. a new species of Nayades of the genus Tamsiella HAAS, belonging to the Juruá River, an affluent of the Solimões River, between Taumaturgo and Fóz do Bréu, Brazil, is described. At the same time an analysis and new regrouping of the existing genera of Monocondylaeinae, is made, giving some considerations about the geographical distribution of its genera in South American waters and its probable phyletic relationship
Smart Grid for the Smart City
Modern cities are embracing cutting-edge technologies to improve the services they offer to the citizens from traffic control to the reduction of greenhouse gases and energy provisioning. In this chapter, we look at the energy sector advocating how Information and Communication Technologies (ICT) and signal processing techniques can be integrated into next generation power grids for an increased effectiveness in terms of: electrical stability, distribution, improved communication security, energy production, and utilization. In particular, we deliberate about the use of these techniques within new demand response paradigms, where communities of prosumers (e.g., households, generating part of their electricity consumption) contribute to the satisfaction of the energy demand through load balancing and peak shaving. Our discussion also covers the use of big data analytics for demand response and serious games as a tool to promote energy-efficient behaviors from end users
Crossover from ballistic to diffusive thermal transport in quantum Langevin dynamics study of a harmonic chain connected to self-consistent reservoirs
Through an exact analysis using quantum Langevin dynamics, we demonstrate the
crossover from ballistic to diffusive thermal transport in a harmonic chain
with each site connected to Ohmic heat reservoirs. The temperatures of the two
heat baths at the boundaries are specified from before whereas the temperatures
of the interior heat reservoirs are determined self-consistently by demanding
that in the steady state, on average, there is no heat current between any such
(self-consistent) reservoir and the harmonic chain. Essence of our study is
that the effective mean free path separating the ballistic regime of transport
from the diffusive one emerges naturally.Comment: 4 pages, 2 figur
Fourier's Law for a Harmonic Crystal with Self-consistent Stochastic Reservoirs
We consider a d-dimensional harmonic crystal in contact with a stochastic
Langevin type heat bath at each site. The temperatures of the "exterior" left
and right heat baths are at specified values T_L and T_R, respectively, while
the temperatures of the "interior" baths are chosen self-consistently so that
there is no average flux of energy between them and the system in the steady
state. We prove that this requirement uniquely fixes the temperatures and the
self consistent system has a unique steady state. For the infinite system this
state is one of local thermal equilibrium. The corresponding heat current
satisfies Fourier's law with a finite positive thermal conductivity which can
also be computed using the Green-Kubo formula. For the harmonic chain (d=1) the
conductivity agrees with the expression obtained by Bolsterli, Rich and
Visscher in 1970 who first studied this model. In the other limit, d>>1, the
stationary infinite volume heat conductivity behaves as 1/(l_d*d) where l_d is
the coupling to the intermediate reservoirs. We also analyze the effect of
having a non-uniform distribution of the heat bath couplings. These results are
proven rigorously by controlling the behavior of the correlations in the
thermodynamic limit.Comment: 33 page
Exact solution of a Levy walk model for anomalous heat transport
The Levy walk model is studied in the context of the anomalous heat
conduction of one dimensional systems. In this model the heat carriers execute
Levy-walks instead of normal diffusion as expected in systems where Fourier's
law holds. Here we calculate exactly the average heat current, the large
deviation function of its fluctuations and the temperature profile of the
Levy-walk model maintained in a steady state by contact with two heat baths
(the open geometry). We find that the current is non-locally connected to the
temperature gradient. As observed in recent simulations of mechanical models,
all the cumulants of the current fluctuations have the same system-size
dependence in the open geometry. For the ring geometry, we argue that a size
dependent cut-off time is necessary for the Levy walk model to behave as
mechanical models. This modification does not affect the results on transport
in the open geometry for large enough system sizes.Comment: 5 pages, 2 figure
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