Introducing Linear Matrix Inequalities in a Control Course

7TH IFAC SYMPOSIUM ON ADVANCES IN CONTROL EDUCATION 21/06/2006 MadridThe important role that linear matrix inequalities have attained in the last years makes it compulsory to include them in the education of a control engineer. As the development of efficient semidefinite programming algorithms date from the early nineties, there is a lack of teaching experience in this field (at least when it is compared with other well established aspects of control theory). This paper proposes a simple way to introduce linear matrix inequalities in a control course. The main objective of the paper is to show that in the formulation of (robust) control problems as linear matrix inequalities a very reduced number of elementary technical results are required. It is illustrated how to introduce, in a progressive way, these technical results along with motivating examples. All of this is done in such a way that it facilitates the assimilation of this important subject. The presented methodology has been successfully applied for more than four years in a doctoral course on control theory

Binary Search Algorithm for Mixed Integer Optimization: Application to energy management in a microgrid

This paper presents a binary search algorithm to deal with binary variables in mixed integer optimization problems. One example of this kind of problem is the optimal operation of hydrogen storage and energy sale and purchase into a microgrids context. In this work was studied a system composed by a microgrid that has a connection with the external electrical network and a charging station for electric cars. The system modeling was carried out by the Energy Hubs methodology. The proposed algorithm transforms the MIQP (Mixed Integer Quadratic Program) problem into a QP (Quadratic Program) that is easier to solve. In this way the overall control task is carried out the electricity purchase and sale to the power grid, maximizes the use of renewable energy sources, manages the use of energy storages and supplies the charge of the parked vehicles.Ministerio de Economía y Competitividad DPI2013-46912-C2-1-RUniversidad de Sevilla CNPq401126/2014-5Universidad de Sevilla CNPq303702/2011-

La respuesta de la comunidad epilítica intermareal natural e impactada por las aguas residuales del Atlántico SO a pulsos (antes/después del verano) y descargas crónicas de aguas residuales en el período 1997 - 2014

Until 2014 Mar del Plata city discharged its untreated sewage effluents to the intertidal sector. This city has a marked seasonality in the urban discharge, varying between 2.8 and 3.5 m3.sec.-1 of effluents before/after summer. The effect on the intertidal benthic community was evaluated in both spatially, in sewage-impacted and reference sites, and temporarily in both the short term, before/after summer, and in long term along nine periods between 1997 - 2014. The bivalve Brachidontes rodriguezii, the ecosystem engineer, reach the maximum dominance and frequency in reference areas. Spatially the presence of opportunistic and tolerant species characterized the impacted areas, while in reference sites sensitive species were prevalent. The opportunistic polychaete species Capitella "capitata" sp. and Alitta succinea were dominant near the sewage discharge in firsts periods. In other periods the indicator species were Rhynchospio glutaea or Boccardia spp. From 2008 the invader Boccardia proboscidea characterized the sewage-impacted sites building massive reefs. The crustaceans Jassa falcata and Caprella sp. were very abundant at intermediate distances from the sewage discharge, while Monocorophium insidiosum was very abundant in sewage-impacted areas. The tolerant and opportunistic species are favored after the summer due to the extra organic matter input. All community parameters showed lower values after the summer, and also a trend to diminish along the studied period.Hasta el año 2014 la ciudad de Mar del Plata descargaba sus efluentes cloacales sin tratamiento al sector intermareal. Esta ciudad tiene una marcada estacionalidad en sus descargas, variando el caudal entre 2,8 a 3,5 m3.seg-1 antes/después del verano. El efecto sobre la comunidad bentónica intermareal fue evaluado en la escala espacial, en sitios de referencia y sitios impactados, y también temporalmente en el corto período de tiempo, antes/después del verano, y a lo largo de nueve períodos entre 1997 - 2014. El bivalvo Brachidontes rodriguezii, el ingeniero ecosistémico, alcanza su máxima dominancia y frecuencia en áreas de referencia. Espacialmente la presencia de especies oportunistas y tolerantes caracterizó los sitios impactados, mientras que en sitios de referencia las especies sensibles son prevalentes. En los primeros períodos el poliqueto oportunista Capitella “capitata” sp. fue dominante cerca de la descarga cloacal, y también Alitta succinea. En periodos posteriores las especies indicadoreas fueron Rhynchospio glutaea o Boccardia spp. Desde 2008 el poliqueto invasor Boccardia proboscidea caracterizó los sitios impactados por la descarga por masivos arrecifes. Los crustáceos Jassa falcata y Caprella sp. fueron muy abundantes a distancias intermedias de la descarga, mientras que Monocorophium insidiosum fue muy abundante en el àrea impactada por la descarga cloacal. Las especies tolerantes u oportunistas se vieron favorecidas después del verano debido al aporte extra de materia orgánica. Todos los parámetros comunitarios mostraron valores menores después del verano, y también se observa una tendencia a disminuir a lo largo de los períodos estudiados

Sine-Gordon ratchets with general periodic, additive, and parametric driving forces

We study the soliton ratchets in the damped sine-Gordon equation with periodic nonsinusoidal, additive, and parametric driving forces. By means of symmetry analysis of this system we show that the net motion of the kink is not possible if the frequencies of both forces satisfy a certain relationship. Using a collective coordinate theory with two degrees of freedom, we show that the ratchet motion of kinks appears as a consequence of a resonance between the oscillations of the momentum and the width of the kink. We show that the equations of motion that fulfill these collective coordinates follow from the corresponding symmetry properties of the original systems. As a further application of the collective coordinate technique we obtain another relationship between the frequencies of the parametric and additive drivers that suppresses the ratchetlike motion of the kink. We check all these results by means of numerical simulations of the originaMEC, (Spain) and by DAAD (Germany) through “Acciones Integradas Hispano-Alemanas” HA2004-0034—D/04/39957MEC Grant No. FIS2005-973Junta de Andalucía under Projects No. 00481, No. P06-FQM-01735, and No. FQM-020

Magnetization structure of a Bloch point singularity

Switching of magnetic vortex cores involves a topological transition characterized by the presence of a magnetization singularity, a point where the magnetization vanishes (Bloch point). We analytically derive the shape of the Bloch point that is an extremum of the free energy with exchange, dipole and the Landau terms for the determination of the local value of the magnetization modulus.Comment: 4 pages, 2 figure

Ratchet effect in a damped sine-Gordon system with additive and parametric ac driving forces

We study in detail the damped sine-Gordon equation, driven by two ac forces (one is added as a parametric perturbation and the other one in an additive way), as an example of soliton ratchets. By means of a collective coordinate approach we derive an analytical expression for the average velocity of the soliton, which allows us to show that this mechanism of transport requires certain relationships both between the frequencies and between the initial phases of the two ac forces. The control of the velocity by the damping coefficient and parameters of the ac forces is also presented and discussed. All these results are subsequently checked by means of simulations for the driven and damped sine-Gordon equation that we have studied.Ministerio de Educación y Ciencia (MEC, Spain) Grant No. HA2004-0034-D/04/39957Ministerio de Educación y Ciencia (MEC, Spain) Grant No. FIS2005-973Junta de Andalucía Project No. 00481Junta de Andalucía Project No. FQM-020

Domain wall dynamics in expanding spaces

We study the effects on the dynamics of kinks due to expansions and contractions of the space. We show that the propagation velocity of the kink can be adiabatically tuned through slow expansions/contractions, while its width is given as a function of the velocity. We also analyze the case of fast expansions/contractions, where we are no longer on the adiabatic regime. In this case the kink moves more slowly after an expansion-contraction cycle as a consequence of loss of energy through radiation. All these effects are numerically studied in the nonlinear Klein-Gordon equations (both for the sine-Gordon and for the phi^4 potential), and they are also studied within the framework of the collective coordinate evolution equations for the width and the center of mass of the kink. These collective coordinate evolution equations are obtained with a procedure that allows us to consider even the case of large expansions/contractions.Comment: LaTeX, 18 pages, 2 figures, improved version to appear in Phys Rev