5,691 research outputs found
Generating Interpretable Fuzzy Controllers using Particle Swarm Optimization and Genetic Programming
Autonomously training interpretable control strategies, called policies,
using pre-existing plant trajectory data is of great interest in industrial
applications. Fuzzy controllers have been used in industry for decades as
interpretable and efficient system controllers. In this study, we introduce a
fuzzy genetic programming (GP) approach called fuzzy GP reinforcement learning
(FGPRL) that can select the relevant state features, determine the size of the
required fuzzy rule set, and automatically adjust all the controller parameters
simultaneously. Each GP individual's fitness is computed using model-based
batch reinforcement learning (RL), which first trains a model using available
system samples and subsequently performs Monte Carlo rollouts to predict each
policy candidate's performance. We compare FGPRL to an extended version of a
related method called fuzzy particle swarm reinforcement learning (FPSRL),
which uses swarm intelligence to tune the fuzzy policy parameters. Experiments
using an industrial benchmark show that FGPRL is able to autonomously learn
interpretable fuzzy policies with high control performance.Comment: Accepted at Genetic and Evolutionary Computation Conference 2018
(GECCO '18
Finding Best Compiler Options for Critical Software Using Parallel Algorithms
The efficiency of a software piece is a key factor for many systems. Real-time programs, critical software, device drivers, kernel OS functions and many other software pieces which are executed thousands or even millions of times per day require a very efficient execution. How this software is built can significantly affect the run time for these programs, since the context is that of compile-once/run-many. In this sense, the optimization flags used during the compilation time are a crucial element for this goal and they could make a big difference in the final execution time. In this paper, we use parallel metaheuristic techniques to automatically decide which optimization flags should be activated during the compilation on a set of benchmarking programs. The using the appropriate flag configuration is a complex combinatorial problem, but our approach is able to adapt the flag tuning to the characteristics of the software, improving the final run times with respect to other spread practicesThis research has been partially funded by the Spanish MINECO and FEDER projects (TIN2014-57341-R (http://moveon.lcc.uma.es), TIN2016-81766-REDT (http://cirti.es), and TIN2017-88213-R (http://6city.lcc.uma.es). It is also funded by Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Design and Experimental Validation of an Explicit MPC Controller for Regulating Temperature in PEM Fuel Cell Systems
This paper proposes a temperature controller for PEM fuel cell systems with an air blower as thermal
circuit. The objective of this controller is to maintain the stack temperature over a given set-point which
is obtained from the results of a real-time optimization algorithm with the goal of minimizing the stack
degradation and maximizing the global efficiency. An Explicit MPC is proposed to deal with this control
problem which presents delays, the critical sampling time, constraints and disturbances. The simulation
results show good performance of the controller which accurately tracks the temperature reference over
the overall range of operating conditions. Furthermore, the controller is implemented in real-time on a
PEM fuel cell test-bench which is installed in the Fuel Cell Laboratory at the University of Seville
Hall response of interacting bosonic atoms in strong gauge fields: from condensed to FQH states
Interacting bosonic atoms under strong gauge fields undergo a series of phase
transitions that take the cloud from a simple Bose-Einstein condensate all the
way to a family of fractional-quantum-Hall-type states [M. Popp, B. Paredes,
and J. I. Cirac, Phys. Rev. A 70, 053612 (2004)]. In this work we demonstrate
that the Hall response of the atoms can be used to locate the phase transitions
and characterize the ground state of the many-body state. Moreover, the same
response function reveals within some regions of the parameter space, the
structure of the spectrum and the allowed transitions to excited states. We
verify numerically these ideas using exact diagonalization for a small number
of atoms, and provide an experimental protocol to implement the gauge fields
and probe the linear response using a periodically driven optical lattice.
Finally, we discuss our theoretical results in relation to recent experiments
with condensates in artificial magnetic fields [ L. J. LeBlanc, K.
Jimenez-Garcia, R. A. Williams, M. C. Beeler, A. R. Perry, W. D. Phillips, and
I. B. Spielman, Proc. Natl. Acad. Sci. USA 109, 10811 (2012)] and we analyze
the role played by vortex states in the Hall response.Comment: 10 pages, 7 figure
VIDA: a virus database system for the organization of animal virus genome open reading frames
VIDA is a new virus database that organizes open reading frames (ORFs) from partial and complete genomic sequences from animal viruses. Currently VIDA includes all sequences from GenBank for Herpesviridae, Coronaviridae and Arteriviridae. The ORFs are organized into homologous protein families, which are identified on the basis of sequence similarity relationships, Conserved sequence regions of potential functional importance are identified and can be retrieved as sequence alignments. We use a controlled taxonomical and functional classification for all the proteins and protein families in the database. When available, protein structures that are related to the families have also been included. The database is available for online search and sequence information retrieval at http://www.biochem.ucl.ac.uk/bsm/virus-database/ VIDA.html
Massive Scaling Limit of beta-Deformed Matrix Model of Selberg Type
We consider a series of massive scaling limits m_1 -> infty, q -> 0, lim m_1
q = Lambda_{3} followed by m_4 -> infty, Lambda_{3} -> 0, lim m_4 Lambda_{3} =
(Lambda_2)^2 of the beta-deformed matrix model of Selberg type (N_c=2, N_f=4)
which reduce the number of flavours to N_f=3 and subsequently to N_f=2. This
keeps the other parameters of the model finite, which include n=N_L and
N=n+N_R, namely, the size of the matrix and the "filling fraction". Exploiting
the method developed before, we generate instanton expansion with finite g_s,
epsilon_{1,2} to check the Nekrasov coefficients (N_f =3,2 cases) to the lowest
order. The limiting expressions provide integral representation of irregular
conformal blocks which contains a 2d operator lim frac{1}{C(q)} : e^{(1/2)
\alpha_1 \phi(0)}: (int_0^q dz : e^{b_E phi(z)}:)^n : e^{(1/2) alpha_2 phi(q)}:
and is subsequently analytically continued.Comment: LaTeX, 21 pages; v2: a reference adde
Measuring gravitational lens time delays using low-resolution radio monitoring observations
Obtaining lensing time delay measurements requires long-term monitoring
campaigns with a high enough resolution (< 1 arcsec) to separate the multiple
images. In the radio, a limited number of high-resolution interferometer arrays
make these observations difficult to schedule. To overcome this problem, we
propose a technique for measuring gravitational time delays which relies on
monitoring the total flux density with low-resolution but high-sensitivity
radio telescopes to follow the variation of the brighter image. This is then
used to trigger high-resolution observations in optimal numbers which then
reveal the variation in the fainter image. We present simulations to assess the
efficiency of this method together with a pilot project observing radio lens
systems with the Westerbork Synthesis Radio Telescope (WSRT) to trigger Very
Large Array (VLA) observations. This new method is promising for measuring time
delays because it uses relatively small amounts of time on high-resolution
telescopes. This will be important because instruments that have high
sensitivity but limited resolution, together with an optimum usage of followup
high-resolution observations from appropriate radio telescopes may in the
future be useful for gravitational lensing time delay measurements by means of
this new method.Comment: 10 pages, 7 figures, accepted by MNRA
Classification of natural flow regimes in the Ebro basin (Spain) by using a wide range of hydrologic parameters
Clasificación de tipos de régimenes naturales de caudales a partir de parámetros de tres componentes del régimen fluvial: magnitud, frecuencia y duración
On the correlation between fragility and stretching in glassforming liquids
We study the pressure and temperature dependences of the dielectric
relaxation of two molecular glassforming liquids, dibutyl phtalate and
m-toluidine. We focus on two characteristics of the slowing down of relaxation,
the fragility associated with the temperature dependence and the stretching
characterizing the relaxation function. We combine our data with data from the
literature to revisit the proposed correlation between these two quantities. We
do this in light of constraints that we suggest to put on the search for
empirical correlations among properties of glassformers. In particular, argue
that a meaningful correlation is to be looked for between stretching and
isochoric fragility, as both seem to be constant under isochronic conditions
and thereby reflect the intrinsic effect of temperature
The communications strategy via Twitter of Nayib Bukele: the millennial president of El Salvador
On June 1, 2019, Nayib Bukele assumed the presidency of the Republic of El Salvador, becoming the youngest leader in the democratic history of this Central American country. His communications strategy on Twitter attracted the attention of the international press, because of a peculiar way of using this tool to tweet direct orders to his governmental team through Twitter, with many of his messages having a humoristic lilt. Observing this way of communicating prompted a wish to investigate the communications strategy of President Nayib Bukele on Twitter. Online tools, such as Twitonomy and Vicinitas, were used for the quantitative analysis of the account over the first two weeks of his presidency. Additionally, an in-depth interview was held with the communications secretary of the government of El Salvador, Sofía Medina. Finally, a broad description of the economic and social situation of the country helps understand the relevance of the data obtained from the analysis, emphasizing the scarce access to both information technology and social networks among the inhabitants.El 1 de junio de 2019 Nayib Bukele tomó posesión como presidente de la República de El Salvador, convirtiéndose en el mandatario más joven en la historia de la democracia de este país de Centroamérica. Su estrategia de comunicación en Twitter llamó la atención de la prensa internacional por una peculiar forma de utilizar esta herramienta, con órdenes directas a su equipo de gobierno a través de Twitter y un tono humorístico en muchos de sus mensajes. Con la observación de este hecho surge la inquietud por investigar la estrategia de comunicación en Twitter del presidente Nayib Bukele. Para el análisis cuantitativo realizado a la cuenta @Nayibbukele durante la primera quincena de gestión se han empleado herramientas online como Twitonomy y Vicinitas. Como complemento, para la interpretación de los resultados obtenidos se ha elaborado una entrevista en profundidad con la responsable de la secretaría de comunicaciones del Gobierno de El Salvador, Sofía Medina. Finalmente, para comprender la relevancia de los datos obtenidos en el análisis, se realiza una amplia descripción de la situación económica y social del país, haciendo énfasis en la falta de acceso a las tecnologías de la información y a las redes sociales por parte de los habitantes
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