A set-membership state estimation algorithm based on DC programming

This paper presents a new approach to guaranteed state estimation for nonlinear discrete-time systems with a bounded description of noise and parameters. The sets of states that are consistent with the evolution of the system, the measured outputs and bounded noise and parameters are represented by zonotopes. DC programming and intersection operations are used to obtain a tight bound. An example is given to illustrate the proposed algorithm.Ministerio de Ciencia y Tecnología DPI2006-15476-C02-01Ministerio de Ciencia y Tecnología DPI2007-66718-C04-01

On the computation of invariant sets for constrained nonlinear systems: An interval arithmetic approach

This paper deals with the computation of control invariant sets for constrained nonlinear systems. The proposed approach is based on the computation of an inner approximation of the one step set, that is, the set of states that can be steered to a given target set by an admissible control action. Based on this procedure, control invariant sets can be computed by recursion. We present a method for the computation of the one-step set using interval arithmetic. The proposed specialized branch and bound algorithm provides an inner approximation with a given bound of the error; this makes it possible to achieve a trade off between accuracy of the computed set and computational burden. Furthermore an algorithm to approximate the one step set by an inner bounded polyhedron is also presented; this allows us to relax the complexity of the obtained set, and to make easier the recursion and storage of the sets.Ministerio de Ciencia y Tecnología DPI2004-07444-c04-01Ministerio de Ciencia y Tecnología DPI2003-04375-c03-01Ministerio de Ciencia y Tecnología DPI2003-07146-c02-0

Compared to private firms, government agencies are more likely to violate regulations and less likely to be punished

Recent events such as the Volkswagen emissions scandal have reminded us that the private sector often break government regulations. But what about government agencies? In new research, that examines compliance with the Clean Air Act and Safe Drinking Water Act, David M. Konisky and Manuel P. Teodoro find that, facing higher compliance costs, government agencies are more likely than private firms to violate such regulations. They also argue that these agencies are less likely to be penalized by government for their infractions compared to private firms

Robust control of the distributed solar collector field ACUREX using MPC for tracking

17th IFAC World Congress 2008. Seoul (Korea). 06/07/2008This paper presents the application of a robust model predictive control for tracking of piece-wise constant references (RMPCT) to a distributed collector field, ACUREX, at the solar power plant of PSA (Solar Plant of Almería). The main characteristic of a solar power plant is that the primary energy source, solar radiation, cannot be manipulated. Solar radiation varies throughout the day, causing changes in plant dynamics and strong disturbances in the process. The real plant is assumed to be modeled as a linear system with additive bounded uncertainties on the states. Under mild assumptions, the proposed RMPCT can steer the uncertain system in an admissible evolution to any admissible steady state, that is, under any change of the set point. This allows us to reject constant disturbances compensating the effect of then changing the setpoint

Propriedades psicométricas de uma escala para medir a gestão da vergonha em adolescentes (Moss-Sast)

(Ahmed, 1999) to measure shame management in adolescents in situations of aggression toward peers. The study was conducted with a sample of 700 students from public secondary schools (N= 700) located in a northwestern state municipality of Mexico. Results enabled to obtain an empirically sustainable measuring model formed by two factors: Acknowledgment and Displacement (X2 = 5.16, p= 0.27; CMIN= 1.29; GFI= .98; CFI= .99; NFI= .97; RMSEA= .05). Evidence was obtained to show that the instrument has criterion validity since it is capable to differentiate between subgroups of students with and without reports of bullying in both factors, Acknowledgment (t= 3.49, gl= 137, p< .001) and Displacement (t= 3.63, gl= 137, p< .001). It was concluded that the results strengthen the original factorial structure of the scale and show the usefulness of the same, both for inquiring about emotions related to moral development and for identifying students involved as aggressors in bullying situations.Se establecieron las evidencias de validez y confiabilidad de la adaptación del cuestionario MOSS-SAST (Ahmed, 1999) para medir el manejo de la vergüenza en adolescentes ante situaciones de agresión hacia los pares. El estudio se realizó en una muestra de estudiantes de escuelas secundarias públicas (N= 700) ubicadas en un municipio de un estado del noroeste de México. Los resultados permitieron obtener un modelo de medición empíricamente sustentable formado por nueve ítems agrupados en dos factores: Reconocimiento y Desplazamiento (c2 = 5.16, p= 0.27; CMIN= 1.29; GFI= .98; CFI= .99; NFI= .97; RMSEA= .05). El instrumento cuenta con evidencias de validez de criterio, ya que establece la diferencia en los factores de reconocimiento (t= 3.49, gl= 137, p< .001) y desplazamiento (t= 3.63, gl= 137, p< .001) en subgrupos de estudiantes con y sin reportes de bullying. Se concluyó que los resultados fortalecen la estructura factorial original de la escala y muestran su utilidad, tanto en la indagación de emociones relacionadas con el del desarrollo moral, como en la identificación de estudiantes involucrados como agresores en situaciones de bullying.Foram estabelecidas as evidências de validade e confiabilidade da adaptação do Questionário MOSS-SAST (Ahmed, 1999) para medir a gestão da vergonha em adolescentes ante situações de agressão contra os pares. O estudo foi realizado com uma amostra de estudantes do ensino fundamental e médio (N=700) de um município do noroeste do México. Os resultados permitiram obter um modelo de medição empiricamente sustentável, formado por nove itens agrupados em dois fatores: reconhecimento e deslocamento (c2 = 5.16, p= 0.27; CMIN= 1.29; GFI= .98; CFI= .99; NFI= .97; RMSEA= .05). O instrumento conta com evidências de validade de critério já que estabelece a diferença nos fatores de reconhecimento (t= 3.49, gl= 137, p< .001) e deslocamento (t= 3.63, gl= 137, p< .001) em subgrupos de estudantes com e sem relatos de bullying. Conclui-se que os resultados fortalecem a estrutura fatorial original da escala e mostram sua utilidade, tanto na indagação de emoções relacionadas com o desenvolvimento moral quanto na identificação de estudantes envolvidos como agressores em situações de bullying

Modelado basado en el paradigma de los energy hubs de una explotación agraria bajo invernadero con apoyo de energías renovables

La gestión de recursos energéticos y materiales en sistemas productivos es un tema habitual en la literatura reciente. En este sentido, se ha desarrollado un modelo de conversión y almacenamiento de recursos heterogéneos en una explotación agraria con el fin de realizar su operación de forma eficiente. A partir del mismo es posible determinar la combinación de recursos de entrada que permiten su operación con el menor coste posible mediante la formulación de un problema de programación lineal en enteros mixta, teniendo en cuenta las características de los equipos y dispositivos del invernadero. Se ha realizado la simulación de un típico día cálido empleando una estrategia de control con horizonte deslizante, observándose en los resultados un uso intensivo de energía solar térmica y fotovoltaica

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

Single-layer economic model predictive control for periodic operation

In this paper we consider periodic optimal operation of constrained periodic linear systems. We propose an economic model predictive controller based on a single layer that unites dynamic real time optimization and control. The proposed controller guarantees closed-loop convergence to the optimal periodic trajectory that minimizes the average operation cost for a given economic criterion. A priori calculation of the optimal trajectory is not required and if the economic cost function is changed, recursive feasibility and convergence to the new periodic optimal trajectory is guaranteed. The results are demonstrated with two simulation examples, a four tank system, and a simplified model of a section of Barcelona's water distribution network.Peer ReviewedPostprint (author’s final draft

Trace element accumulation in woody plants of the Guadiamar Valley, SW Spain: A large-scale phytomanagement case study

10 pages, 3 figures, 5 tables, 50 references.Phytomanagement employs vegetation and soil amendments to reduce the environmental risk posed by contaminated sites. We investigated the distribution of trace elements in soils and woody plants from a large phytomanaged site, the Guadiamar Valley (SW Spain), 7 years after a mine spill, which contaminated the area in 1998. At spill-affected sites, topsoils (0e25 cm) had elevated concentrations of As (129 mg kg 1), Bi (1.64 mg kg 1), Cd (1.44 mg kg 1), Cu (115 mg kg 1), Pb (210 mg kg 1), Sb (13.8 mg kg 1), Tl (1.17 mg kg 1) and Zn (457 mg kg 1). Trace element concentrations in the studied species were, on average, within the normal ranges for higher plants. An exception was white poplar (Populus alba), which accumulated Cd and Zn in leaves up to 3 and 410 mg kg 1 respectively. We discuss the results with regard to the phytomanagement of trace element contaminated sites.We acknowledge the Regional Ministry of Environment (Junta de Andalucía) for supporting this study within the SECOVER research programme, and the Spanish Ministry of Education for a PFU grant awarded to M.T.D.Peer reviewe

Hybrid modeling of renewable energy systems and its application to a hot water solar plant

IFAC - CONFERENCE ON CONTROL METHODOLOGIES AND TECHNOLOGY FOR ENERGY EFFICIENCY 29/03/2010 Vilamoura, PortugalA family of models that can be applied to various types of renewable energy plants is proposed. The methodology is used to model a solar plant for the production of sanitary water (the hot water production system installed at the “Hospital Universitario Virgen del Rocío”, Seville, Spain). A detailed examination of the behavior of the plant has produced a model which has served to identify niches of inefficiency in the operation. The model is later used to tune the parameters of a controller to improve operation.Ministerio de Ciencia y Tecnología DPI 2007-66718-C04-01Junta de Andalucía TEP-0272