7,394 research outputs found
Optimized FPGA Implementation of Model Predictive Control for Embedded Systems Using High-Level Synthesis Tool
Model predictive control (MPC) is an optimization-based strategy for high-performance control that is attracting increasing interest. While MPC requires the online solution of an optimization problem, its ability to handle multivariable systems and constraints makes it a very powerful control strategy specially for MPC of embedded systems, which have an ever increasing amount of sensing and computation capabilities. We argue that the implementation of MPC on field programmable gate arrays (FPGAs) using automatic tools is nowadays possible, achieving cost-effective successful applications on fast or resource-constrained systems. The main burden for the implementation of MPC on FPGAs is the challenging design of the necessary algorithms. We outline an approach to achieve a software-supported optimized implementation of MPC on FPGAs using high-level synthesis tools and automatic code generation. The proposed strategy exploits the arithmetic operations necessaries to solve optimization problems to tailor an FPGA design, which allows a tradeoff between energy, memory requirements, cost, and achievable speed. We show the capabilities and the simplicity of use of the proposed methodology on two different examples and illustrate its advantages over a microcontroller implementation
Deep Learning-Based Magnetic Coupling Detection for Advanced Induction Heating Appliances
Induction heating has become the reference technology for domestic heating applications due to its benefits in terms of performance, efficiency and safety, among others. In this context, recent design trends aim at providing highly flexible cooking surfaces composed of multi-coil structures. As in many other wireless power transfer systems, one of the main challenges to face is the proper detection of the magnetic coupling with the induction heating load in order to provide improved thermal performance and safe power electronic converter operation. This is specially challenging due to the high variability in the materials used in cookware as well as the random pot placement in flexible induction heating appliances. This paper proposes the use of deep learning techniques in order to provide accurate area overlap estimation regardless of the used pot and its position. An experimental test-bench composed of a complete power converter, multi-coil system and real-Time measurement system has been implemented and used in this study to characterize the parameter variation with overlapped area. Convolutional neural networks are then proposed as an effective method to estimate the covered area, and several implementations are studied and compared according to their computational cost and accuracy. As a conclusion, the presented deep learning-based technique is proposed as an effective tool to estimate the magnetic coupling between the coil and the induction heating load in advanced induction heating appliances
Influence of molecular temperature on the coherence of fullerenes in a near-field interferometer
We study C70 fullerene matter waves in a Talbot-Lau interferometer as a
function of their temperature. While the ideal fringe visibility is observed at
moderate molecular temperatures, we find a gradual degradation of the
interference contrast if the molecules are heated before entering the
interferometer. A method is developed to assess the distribution of the
micro-canonical temperatures of the molecules in free flight. This way the
heating-dependent reduction of interference contrast can be compared with the
predictions of quantum theory. We find that the observed loss of coherence
agrees quantitatively with the expected decoherence rate due to the thermal
radiation emitted by the hot molecules.Comment: 11 pages, 9 figure
Synthesis, Growth and Spectroscopic Studies of L-Alanine Hydrogen Chloride(Lahc) Crystals
L-alanine Hydrogen Chloride (LAHC) salt was synthesized by taking L-alanine and hydrochloric acid in 1:1 molar ratio and the solubility of the synthesized salt in deionized water was determined at different temperatures. Single crystals of L-alanine Hydrogen Chloride (LAHC) were grown by solution method with slow evaporation technique. The grown crystals were characterized by single crystal X-ray diffraction (XRD) analysis, FTIR studies and UV-visible transmittance studies and the NLO activity of the grown crystal has been checked by Second Harmonic Generation (SHG) test.ÂÂ
Inversion formulas for the broken-ray Radon transform
We consider the inverse problem of the broken ray transform (sometimes also
referred to as the V-line transform). Explicit image reconstruction formulas
are derived and tested numerically. The obtained formulas are generalizations
of the filtered backprojection formula of the conventional Radon transform. The
advantages of the broken ray transform include the possibility to reconstruct
the absorption and the scattering coefficients of the medium simultaneously and
the possibility to utilize scattered radiation which, in the case of the
conventional X-ray tomography, is typically discarded.Comment: To be submitted to Inverse Problem
Numerical simulations challenged on the prediction of massive subhalo abundance in galaxy clusters: the case of Abell 2142
In this Letter we compare the abundance of member galaxies of a rich, nearby
() galaxy cluster, Abell 2142, with that of halos of comparable virial
mass extracted from sets of state-of-the-art numerical simulations, both
collisionless at different resolutions and with the inclusion of baryonic
physics in the form of cooling, star formation, and feedback by active galactic
nuclei. We also use two semi-analytical models to account for the presence of
orphan galaxies. The photometric and spectroscopic information, taken from the
Sloan Digital Sky Survey Data Release 12 (SDSS DR12) database, allows us to
estimate the stellar velocity dispersion of member galaxies of Abell 2142. This
quantity is used as proxy for the total mass of secure cluster members and is
properly compared with that of subhalos in simulations. We find that simulated
halos have a statistically significant ( sigma confidence level)
smaller amount of massive (circular velocity above )
subhalos, even before accounting for the possible incompleteness of
observations. These results corroborate the findings from a recent strong
lensing study of the Hubble Frontier Fields galaxy cluster MACS J0416
\citep{grillo2015} and suggest that the observed difference is already present
at the level of dark matter (DM) subhalos and is not solved by introducing
baryonic physics. A deeper understanding of this discrepancy between
observations and simulations will provide valuable insights into the impact of
the physical properties of DM particles and the effect of baryons on the
formation and evolution of cosmological structures.Comment: 8 pages, 2 figures. Modified to match the version published in ApJ
Characterizing Diffused Stellar Light in simulated galaxy clusters
[Abridged] In this paper, we carry out a detailed analysis of the performance
of two different methods to identify the diffuse stellar light in cosmological
hydrodynamical simulations of galaxy clusters. One method is based on a
dynamical analysis of the stellar component. The second method is closer to
techniques commonly employed in observational studies. Both the dynamical
method and the method based on the surface brightness limit criterion are
applied to the same set of hydrodynamical simulations for a large sample about
80 galaxy clusters.
We find significant differences between the ICL and DSC fractions computed
with the two corresponding methods, which amounts to about a factor of two for
the AGN simulations, and a factor of four for the CSF set. We also find that
the inclusion of AGN feedback boosts the DSC and ICL fractions by a factor of
1.5-2, respectively, while leaving the BCG+ICL and BCG+DSC mass fraction almost
unchanged. The sum of the BCG and DSC mass stellar mass fraction is found to
decrease from ~80 per cent in galaxy groups to ~60 per cent in rich clusters,
thus in excess of what found from observational analysis.
We identify the average surface brightness limits that yields the ICL
fraction from the SBL method close to the DSC fraction from the dynamical
method. These surface brightness limits turn out to be brighter in the CSF than
in the AGN simulations. This is consistent with the finding that AGN feedback
makes BCGs to be less massive and with shallower density profiles than in the
CSF simulations. The BCG stellar component, as identified by both methods, are
slightly older and more metal-rich than the stars in the diffuse component.Comment: 18 Pages, 15 figures. Matches to MNRAS published versio
The recycling of gas and metals in galaxy formation: predictions of a dynamical feedback model
We present results of a new feedback scheme implemented in the Munich galaxy
formation model. The new scheme includes a dynamical treatment of galactic
winds powered by supernovae explosions and stellar winds in a cosmological
context. We find that such a scheme is a good alternative to
empirically-motivated recipes for feedback in galaxy formation. Model results
are in good agreement with the observed luminosity functions and stellar mass
function for galaxies in the local Universe. In particular, the new scheme
predicts a number density of dwarfs that is lower than in previous models. This
is a consequence of a new feature of the model, that allows an estimate of the
amount of mass and metals that haloes can permanently deposit into the IGM.
This loss of material leads to the suppression of star formation in small
haloes and therefore to the decrease in the number density of dwarf galaxies.
The model is able to reproduce the observed mass-stellar metallicity and
luminosity-gas metallicity relationships. This demonstrates that our scheme
provides a significant improvement in the treatment of the feedback in dwarf
galaxies. Despite these successes, our model does not reproduce the observed
bimodality in galaxy colours and predicts a larger number of bright galaxies
than observed. Finally, we investigate the efficiency of metal injection in
winds and in the intergalactic medium. We find that galaxies that reside in
haloes with M_vir < 10^12 M_sun/h may deposit most of their metal mass into the
intergalactic medium, while groups and clusters at z=0 have lost at most a few
percent of their metals before the bulk of the halo mass was accreted.Comment: 13 pages, 10 figures. Accepted by MNRAS. The galaxy catalogues at z=0
can be downloaded from
http://www.virgo.sussex.ac.uk/Millennium/millennium.htm
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