Sistema integrado de simulación y control, SISC

En el área de control convergen conocimientos de diferentes disciplinas: matemáticas, procesos y computación. Un buen ingeniero de control debe manejar una gran variedad de conceptos técnicas estando en capacidad de aplicarlos a los problemas reales de la industria; tareas típicas incluyen modelaje matemático, análisis, simulación, diseño e implementación; la habilidad para solucionar estos problemas depende en gran parte del dominio de conceptos como realimentación, estabilidad y robustez. También se hace necesario tener un buen entendimiento sobre el comportamiento de sistemas dinámicos. Este conjunto de necesidades dieron origen al desarrollo del software de análisis, simulación y control en tiempo real de procesos industriales, el cual se ha denominado SISC

GPI-repetitive control for linear systems with parameter uncertainty / variation

El problema de control de sistemas lineales para seguimiento o rechazo de señales periódicas con incertidumbre / variación paramétrica ha sido considerado desde varias perspectivas. Este trabajo presenta una propuesta de combinación de la técnica de control repetitivo con la técnica de control Proporcional Integral Generalizado (GPI). La adecuación y combinación de estas técnicas se realiza en un contexto de tiempo discreto. El control repetitivo se presenta como una técnica, basada en el principio del modelo interno, apta para el rechazo o seguimiento de señales periódicas. Por otra parte, la técnica de control GPI es una estrategia de diseño de controladores robustos lineales capaces de gestionar adecuadamente tanto perturbaciones exógenas de tipo estructurado así como la incertidumbre / variación de planta. Se plantea que el control GPI garantice unas condiciones de estabilidad y desempeño adecuadas para el correcto funcionamiento del control repetitivo sobre plantas lineales que refieran incertidumbre / variación paramétrica. Se presentan adicionalmente análisis de estabilidad y desempeño en términos de la respuesta en frecuencia tomando diferentes escenarios de incertidumbre en los parámetros y graficando las condiciones de estabilidad. Complementariamente, se realizan comparaciones con estrategias clásicas a nivel del control complementario, que han resultado efectivas para problemas de control similares, y se ilustran los análisis por medio de simulaciones.Robust repetitive control problems for uncertain linear systems have been considered by different approaches. This article proposes the use of Repetitive Control and Generalized Proportional Integral (GPI) Control in a complementary fashion. The conditioning and coupling of these techniques has been done in a time discrete context. Repetitive control is a control technique, based on the internal model principle, which yields perfect asymptotic tracking and rejection of periodic signals. On the other hand, GPI control is established as a robust linear control system design technique that is able to reject structured time polynomial additive perturbation, in particular, parameter uncertainty that can be locally approximated by time polynomial signal. GPI control provides a suitable stability and robustness conditions for the proper Repetitive Control operation. A stability analysis is presented under the frequency response framework using plant samples for different parameter uncertainty conditions. We carry out some comparative stability analysis with other complementary control approaches that has been effective for this kind of task, enhancing a better robustness and an improved performance for the GPI case. Illustrative simulation examples are presented which validate the proposed approach

Control proporcional integral generalizado para señales periódicas

En este trabajo se analizan las capacidades de la técnica de control Proporcional Integral Generalizado para el rechazo/seguimiento de señales periódicas. De esta manera, se presenta un control basado en un observador de alta ganancia bajo el enfoque del rechazo activo de perturbaciones. Se compara su desempeño con otros tipos de compensadores que han mostrado ser eficaces para este tipo de problema de control y se realizan análisis de desempeño frente a diferentes condiciones de operación por medio de simulaciones numéricas. Los análisis y simulaciones demuestran un desempeño similar al conseguido con las técnicas convencionales, a la frecuencias de operación nominal y, por otra parte, una notable ventaja a regímenes de operación con frecuencias variables

Robust Active Disturbance Rejection Control Approach to Maximize Energy Capture in Variable-Speed Wind Turbines

This paper proposes an alternative robust observer-based linear control technique to maximize energy capture in a 4.8 MW horizontal-axis variable-speed wind turbine. The proposed strategy uses a generalized proportional integral (GPI) observer to reconstruct the aerodynamic torque in order to obtain a generator speed optimal trajectory. Then, a robust GPI observer-based controller supported by an active disturbance rejection (ADR) approach allows asymptotic tracking of the generator speed optimal trajectory. The proposed methodology controls the power coefficient, via the generator angular speed, towards an optimum point at which power coefficient is maximum. Several simulations (including an actuator fault) are performed on a 4.8 MW wind turbine benchmark model in order to validate the proposed control strategy and to compare it to a classical controller. Simulation and validation results show that the proposed control strategy is effective in terms of power capture and robustness

Hardware copyleft como herramienta para la enseñanza del procesamiento de señales e imágenes

El procesamiento digital de señales y de imágenes es un área que abarca un amplio rango de aplicaciones académicas y comerciales. Es tema obligado en la mayoría de los centros educativos de formación superior y, gracias al estado actual de la industria de los semiconductores es posible obtener dispositivos especializados en este tipo de procesamiento, lo que permite la creación de productos comercializables en esta área. Esto, es de vital importancia en paises en vía de desarrollo, como Colombia, donde la industria electrónica casi no existe y depende por completo de productos provenientes de paises más desarrollados, en especial de productos asiáticos. Este artículo presenta dos plataformas hardware copyleft que pueden ser estudiadas, reproducidas y modificadas, incluso para fines comerciales, proporcionando una herramienta para el estudio de procesamiento de señales y de imágenes y un punto de partida para el desarrollo de empresas de base tecnológica que permitan disminuir los altos niveles de desempleo de los profesionales en áreas afines

Generation and processing of complex photon states with quantum frequency combs

The development of technologies for quantum information (QI) science demands the realization. and precise control of complex (multipartite and high dimensional) entangled systems on practical and scalable platforms. Quantum frequency combs (QFCs) represent a powerful tool towards this goal. They enable the generation of complex photon states within a single spatial mode as well as their manipulation using standard fiber-based telecommunication components. Here, we review recent progress in the development of QFCs, with a focus on results that highlight their importance for the realization of complex quantum states. In particular, we outline recent work on the use of integrated QFCs for the generation of high-dimensional multipartite optical cluster states - lying at the basis of measurement-based quantum computation. These results confirm that the QFC approach can provide a stable, practical, low-cost, and established platform for the development of quantum technologies, paving the way towards the advancement of QI science for out-of-the-lab applications, ranging from practical quantum computing to more secure communications

Mitochondrial Na+ controls oxidative phosphorylation and hypoxic redox signalling

All metazoans depend on O2 delivery and consumption by the mitochondrial oxidative phosphorylation (OXPHOS) system to produce energy. A decrease in O2 availability (hypoxia) leads to profound metabolic rewiring. In addition, OXPHOS uses O2 to produce reactive oxygen species (ROS) that can drive cell adaptations through redox signalling, but also trigger cell damage1–4, and both phenomena occur in hypoxia4–8. However, the precise mechanism by which acute hypoxia triggers mitochondrial ROS production is still unknown. Ca2+ is one of the best known examples of an ion acting as a second messenger9, yet the role ascribed to Na+ is to serve as a mere mediator of membrane potential and collaborating in ion transport10. Here we show that Na+ acts as a second messenger regulating OXPHOS function and ROS production by modulating fluidity of the inner mitochondrial membrane (IMM). We found that a conformational shift in mitochondrial complex I during acute hypoxia11 drives the acidification of the matrix and solubilization of calcium phosphate precipitates. The concomitant increase in matrix free-Ca2+ activates the mitochondrial Na+/Ca2+ exchanger (NCLX), which imports Na+ into the matrix. Na+ interacts with phospholipids reducing IMM fluidity and mobility of free ubiquinone between complex II and complex III, but not inside supercomplexes. As a consequence, superoxide is produced at complex III, generating a redox signal. Inhibition of mitochondrial Na+ import through NCLX is sufficient to block this pathway, preventing adaptation to hypoxia. These results reveal that Na+ import into the mitochondrial matrix controls OXPHOS function and redox signalling through an unexpected interaction with phospholipids, with profound consequences in cellular metabolism

Varespladib and cardiovascular events in patients with an acute coronary syndrome: the VISTA-16 randomized clinical trial

IMPORTANCE: Secretory phospholipase A2(sPLA2) generates bioactive phospholipid products implicated in atherosclerosis. The sPLA2inhibitor varespladib has favorable effects on lipid and inflammatory markers; however, its effect on cardiovascular outcomes is unknown. OBJECTIVE: To determine the effects of sPLA2inhibition with varespladib on cardiovascular outcomes. DESIGN, SETTING, AND PARTICIPANTS: A double-blind, randomized, multicenter trial at 362 academic and community hospitals in Europe, Australia, New Zealand, India, and North America of 5145 patients randomized within 96 hours of presentation of an acute coronary syndrome (ACS) to either varespladib (n = 2572) or placebo (n = 2573) with enrollment between June 1, 2010, and March 7, 2012 (study termination on March 9, 2012). INTERVENTIONS: Participants were randomized to receive varespladib (500 mg) or placebo daily for 16 weeks, in addition to atorvastatin and other established therapies. MAIN OUTCOMES AND MEASURES: The primary efficacy measurewas a composite of cardiovascular mortality, nonfatal myocardial infarction (MI), nonfatal stroke, or unstable angina with evidence of ischemia requiring hospitalization at 16 weeks. Six-month survival status was also evaluated. RESULTS: At a prespecified interim analysis, including 212 primary end point events, the independent data and safety monitoring board recommended termination of the trial for futility and possible harm. The primary end point occurred in 136 patients (6.1%) treated with varespladib compared with 109 patients (5.1%) treated with placebo (hazard ratio [HR], 1.25; 95%CI, 0.97-1.61; log-rank P = .08). Varespladib was associated with a greater risk of MI (78 [3.4%] vs 47 [2.2%]; HR, 1.66; 95%CI, 1.16-2.39; log-rank P = .005). The composite secondary end point of cardiovascular mortality, MI, and stroke was observed in 107 patients (4.6%) in the varespladib group and 79 patients (3.8%) in the placebo group (HR, 1.36; 95% CI, 1.02-1.82; P = .04). CONCLUSIONS AND RELEVANCE: In patients with recent ACS, varespladib did not reduce the risk of recurrent cardiovascular events and significantly increased the risk of MI. The sPLA2inhibition with varespladib may be harmful and is not a useful strategy to reduce adverse cardiovascular outcomes after ACS. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01130246. Copyright 2014 American Medical Association. All rights reserved