24,012 research outputs found
Boletim Agrometeorológico ano 2002 para a sub-região da Nhecolândia, Pantanal, Mato Grosso do Sul, Brasil.
Este boletim tem o intuito de difundir as informações agroclimáticas coletadas no Pantanal da Nhecolândia, visando subsidiar a pesquisa agropecuária da região, além de atender todos àqueles que necessitam de informações dessa natureza.bitstream/CPAP/55971/1/DOC76.pdfFormato Eletrônic
Remote experimentation: integrating research, education, and industrial application
This paper presents a low-cost scaled model of a silo for drying and airing cereal grains. It allows the control and monitor of several parameters associated to the silo's operation, through a remote accessible infrastructure. The scaled model consists of a 2.50 m wide × 2.10 m long plant with all control and monitor capacities provided by micro-Web servers. An application running on the micro-Web servers enables storing all parameters in a data basis for later analysis. The implemented model aims to support a remote experimentation facility for technological education, research-oriented tutorials, and industrial applications. Given the low-cost requirement, this remote facility can be easily replicated in other institutions to support a network of remote labs, which encompasses the concurrent access of several users (e.g. students)
Geometric scaling of purely-elastic flow instabilities
We present a combined experimental, numerical and theoretical investigation
of the geometric scaling of the onset of a purely-elastic flow instability in a
serpentine channel. Good qualitative agreement is obtained between experiments,
using dilute solutions of flexible polymers in microfluidic devices, and
two-dimensional numerical simulations using the UCM model. The results are
confirmed by a simple theoretical analysis, based on the dimensionless
criterion proposed by Pakdel-McKinley for onset of a purely-elastic
instability
From cheating to teaching: a path for conversion of illegal gambling machines
Video poker machines, a former symbol of fraud and gambling in Brazil, are now being
converted into computer-based educational tools for Brazilian public primary schools and also
for governmental and non-governmental institutions dealing with communities of poverty and
social exclusion, in an attempt to reduce poverty risks (decrease money spent on gambling)
and promote social inclusion (increase access and motivation to education). Thousands of
illegal gambling machines are seized by federal authorities, in Brazil, every year, and usually
destroyed at the end of the criminal apprehension process.
This paper describes a project developed by the University of Southern Santa Catarina, Brazil,
responsible for the conversion process of gambling machines, and the social inclusion
opportunities derived from it. All project members worked on a volunteer basis, seeking to
promote social inclusion of Brazilian young boys and girls, namely through digital inclusion. So
far, the project has been able to convert over 200 gambling machines and install them in over
40 public primary schools, thus directly benefiting more than 12,000 schoolchildren.
The initial motivation behind this project was technology based, however the different options
arising from the conversion process of the gambling machines have also motivated a rather
innovative and unique experience in allowing schoolchildren and young people with special
(educational) needs to access to computer-based pedagogical applications. The availability of these converted machines also helps to place Information and
Communication Technologies (ICT) in the very daily educational environment of these children
and youngsters, thus serving social and cultural inclusion aspects, by establishing a dialogue
with the community and their technological expectations, and also directly contributing to their
digital literacy
The extended gaussian ensemble and metastabilities in the Blume-Capel model
The Blume-Capel model with infinite-range interactions presents analytical
solutions in both canonical and microcanonical ensembles and therefore, its
phase diagram is known in both ensembles. This model exhibits nonequivalent
solutions and the microcanonical thermodynamical features present peculiar
behaviors like nonconcave entropy, negative specific heat, and a jump in the
thermodynamical temperature. Examples of nonequivalent ensembles are in general
related to systems with long-range interactions that undergo canonical
first-order phase transitions. Recently, the extended gaussian ensemble (EGE)
solution was obtained for this model. The gaussian ensemble and its extended
version can be considered as a regularization of the microcanonical ensemble.
They are known to play the role of an interpolating ensemble between the
microcanonical and the canonical ones. Here, we explicitly show how the
microcanonical energy equilibrium states related to the metastable and unstable
canonical solutions for the Blume-Capel model are recovered from EGE, which
presents a concave "extended" entropy as a function of energy.Comment: 6 pages, 5 eps figures. Presented at the XI Latin American Workshop
on Nonlinear Phenomena, October 05-09 (2009), B\'uzios (RJ), Brazil. To
appear in JPC
Large deviations for non-uniformly expanding maps
We obtain large deviation results for non-uniformly expanding maps with
non-flat singularities or criticalities and for partially hyperbolic
non-uniformly expanding attracting sets. That is, given a continuous function
we consider its space average with respect to a physical measure and compare
this with the time averages along orbits of the map, showing that the Lebesgue
measure of the set of points whose time averages stay away from the space
average decays to zero exponentially fast with the number of iterates involved.
As easy by-products we deduce escape rates from subsets of the basins of
physical measures for these types of maps. The rates of decay are naturally
related to the metric entropy and pressure function of the system with respect
to a family of equilibrium states. The corrections added to the published
version of this text appear in bold; see last section for a list of changesComment: 36 pages, 1 figure. After many PhD students and colleagues having
pointed several errors in the statements and proofs, this is a correction to
published article answering those comments. List of main changes in a new
last sectio
Assessing the accuracy of different remapping methods in adaptive mesh refinement
Additive manufacturing of metals has attracted much attention over the last years, promoting the development of several computational models for numerical simulation of the laser powder bed fusion (LPBF) process. Nevertheless, the finite element analysis of the LPBF process requires a large computational time. Thus, adaptive mesh refinement strategies are commonly adopted to reduce computational cost, which require some remapping procedure to transfer the state variables from the old mesh to the new one. The present study analyses two different remapping algorithms, namely the Inverse Isoparametric Mapping (IIM) and the Dual Kriging (DK) method. The IIM method uses the shape functions of the finite elements, while the DK method provides an explicit parametric interpolation. The case study adopted covers both coarsening and refinement procedures, using a mathematical function to define the mapped state variable. The accuracy of the remapping methods was lower in the refinement in comparison with the coarsening procedure. The error in the approximation is lower using the DK method in comparison with the IIM method. However, the IIM method does not suffer from error propagation in successive stages of either refinement/derefinement or coarsening/decoarsening.The authors gratefully acknowledge the financial support of the projects POCI-01-0145-FEDER031657 (PTDC/EME-EME/31657/2017) and UIDB/00285/2020 financed by the Operational Program for Competitiveness and Internationalization, in its FEDER/FNR component, and the Portuguese Foundation of Science and Technology (FCT), in its State Budget component (OE). The first author is also grateful to the FCT for the PhD grant with reference 2020.05267.BD
Functionalizing self-assembled GaN quantum dot superlattices by Eu-implantation
Self-assembled GaN quantum dots (QDs) stacked in superlattices (SL) with AlN spacer layers were implanted with Europium ions to fluences of 1013, 1014, and 1015 cm−2. The damage level introduced in the QDs by the implantation stays well below that of thick GaN epilayers. For the lowest fluence, the structural properties remain unchanged after implantation and annealing while for higher fluences the implantation damage causes an expansion of the SL in the [0001] direction which increases with implantation fluence and is only partly reversed after thermal annealing at 1000 °C. Nevertheless, in all cases, the SL quality remains very good after implantation and annealing with Eu ions incorporated preferentially into near-substitutional cation sites. Eu3+ optical activation is achieved after annealing in all samples. In the sample implanted with the lowest fluence, the Eu3+ emission arises mainly from Eu incorporated inside the QDs while for the higher fluences only the emission from Eu inside the AlN-buffer, capping, and spacer layers is observed.
© 2010 American Institute of PhysicsFCT-PTDC/CTM/100756/2008program PESSOA EGIDE/GRICESFCT-SFRH/BD/45774/2008FCT-SFRH/BD/44635/200
Amnestically induced persistence in random walks
We study how the Hurst exponent depends on the fraction of the
total time remembered by non-Markovian random walkers that recall only the
distant past. We find that otherwise nonpersistent random walkers switch to
persistent behavior when inflicted with significant memory loss. Such memory
losses induce the probability density function of the walker's position to
undergo a transition from Gaussian to non-Gaussian. We interpret these findings
of persistence in terms of a breakdown of self-regulation mechanisms and
discuss their possible relevance to some of the burdensome behavioral and
psychological symptoms of Alzheimer's disease and other dementias.Comment: 4 pages, 3 figs, subm. to Phys. Rev. Let
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