A review of convex approaches for control, observation and safety of linear parameter varying and Takagi-Sugeno systems

This paper provides a review about the concept of convex systems based on Takagi-Sugeno, linear parameter varying (LPV) and quasi-LPV modeling. These paradigms are capable of hiding the nonlinearities by means of an equivalent description which uses a set of linear models interpolated by appropriately defined weighing functions. Convex systems have become very popular since they allow applying extended linear techniques based on linear matrix inequalities (LMIs) to complex nonlinear systems. This survey aims at providing the reader with a significant overview of the existing LMI-based techniques for convex systems in the fields of control, observation and safety. Firstly, a detailed review of stability, feedback, tracking and model predictive control (MPC) convex controllers is considered. Secondly, the problem of state estimation is addressed through the design of proportional, proportional-integral, unknown input and descriptor observers. Finally, safety of convex systems is discussed by describing popular techniques for fault diagnosis and fault tolerant control (FTC).Peer ReviewedPostprint (published version

Caracterización de la Hemorragia digestiva alta en pacientes de cuidado crítico del Hospital Militar Central entre septiembre de 2006 y agosto de 2008

La hemorragia digestiva en los pacientes de cuidado crítico ha sido descrita en la literatura desde los 1980s. Los estudios endoscópicos generalmente indican que aproximadamente 75% a 100% de los pacientes críticamente enfermos presentan lesiones endoscópicas visibles cuando la endoscopia es realizada en los primeros 1 a 3 días de la enfermedad. La prevalencia de sangrado digestivo varia de 15% a 50% si se una como desenlace el resultado de sangre oculta en heces o descenso de la hemoglobina. El sangrado clínicamente evidente (hematemesis o retorno por sonda nasogastrica de sangre roja) ocurre en aproximadamente 5% a 25% de los pacientes críticamente enfermos. Sin embargo aproximadamente un 20% de los sangrados clínicamente evidentes tienen significancia clínica. La incidencia de sangrado clínicamente significativo en pacientes críticamente enfermos se ha estimado en aproximadamente 3% a 4%. El propósito principal de nuestra investigación es el de caracterizar la hemorragia digestiva en los pacientes críticamente enfermos en nuestro hospital universitario de alta complejidad en el periodo comprendido desde septiembre de 2006 y agosto de 2208. Es así como con un estudio de tipo descriptivo retrospectivo realizamos un análisis de los datos que reposan en nuestros registros del servicio de gastroenterología. Se consideraron como variables la edad, género diagnóstico endoscópico. Entre septiembre de 2006 y agosto de 2008 se realizaron 62 endoscopias tico por sospecha de hemorragia digestiva alta, de las cuales 5 (8%) fueron negativas para hemorragia digestiva alta, por lo que se tomaron 57 procedimientos para el análisis. El promedio de edad de presentación fue de 57 años. La distribución por genero fue en hombres 40 (70%) y en mujeres 17 (30%). La incidencia de hemorragia digestiva alta en las unidades de cuidado intensivo fue de 2.07% la cual se encuentra dentro de los porcentajes observados en otros estudios (1.5 a 5%). La causa más común de hemorragia digestiva en UCI fue la úlcera péptica con 27 casos (47%), siendo de origen gástrico 15 (26%) y duodenal 12 (21%), la segunda causa en frecuencia de sangrado fue la esofagitis erosiva con 9 pacientes (15%), seguida de la gastritis erosiva con 8 pacientes (14%). En orden descendente de frecuencia las causas siguientes fueron: Desgarro de Mallory Weiss (8%), duodenitis erosiva (7%), várices esofágicas (3.5%) y lesión de Dieulafoy (3.5%). Conclusion: La incidencia de hemorragia digestiva alta en cuidado intensivo del hospital militar central es similar a la reportada en otros estudios realizados en centros de alto nivel de complejidad en otros países. Las ulceras gástrica y duodenal por estrés se constituyen en la principal causa de hemorragia de vías digestivas altas en nuestras unidades de cuidado intensivoAcute GI bleeding in critically ill patients has been described in the medical literature since the 1800s. Endoscopic studies generally indicate that approximately 75% to 100% of critically ill patients have gross gastric lesions visible when endoscopy is performed within the first 1 to 3 days of illness.3,6,7 The prevalence of gastrointestinal bleeding ranges from 15% to 50% if a drop in hemoglobin level or positive stool occult blood test) is used as an end point.8,9 Clinically overt bleeding (hematemesis or nasogastric lavage positive for bright red blood) occurs in about 5% to 25% of critically ill patients However, approximately 20% of clinically evident bleeding is reported to be clinically significant.12 The incidence of clinically significant GI bleeding has been estimated to be approximately 3% to 4%. The main purpose of our research is to characterize the gastrointestinal bleeding in critically ill patients hospitalized in our large tertiary center Hospital Militar Central between September 2006 and august 2009. By means of a retrospective descriptive study, we performed an analysis of the data of the records held in the gastroenterology service. Several variables are considered, such as age, gender and endoscopic diagnosis. Results: Between September 2006 and august 2008 62 upper endoscopies were made for suspect of gastrointestinal bleeding, 5% were reported as normal, so we take 57 procedures for analysis. The median age of presentation was 57 years old. The gender distribution was males 40 (70%) and females 17 (30%). The incidence of upper gastrointestinal bleeding in ICUs was 2,07%, which is is consistent with the reports observed in other studies (1,5 5%). The most common cause of gastrointestinal bleeding was peptic ulcer with 27 cases (47%), being of gastric origin 15 (26%) and duodenal origin 12 (21%), the second cause in frequency was erosive esophagitis with 9 patients (15%) followed by erosive gastritis with 8 patients (14%). In descending order the next causes were: Mallory Weiss tear (8%), erosive duodenitis (7%), esophageal variceal bleeding (3,5%) and Dieulafoys lesson (3,5%). Conclusion: The incidence of upper gastrointestinal bleeding in the ICUs of Hospital Militar is similar to that reported in other studies in high complexity centers in other countries. The stress related gastric a duodenal ulcers became the principal source of upper gastrointestinal bleedin

On control of discrete-time state-dependent jump linear systems with probabilistic constraints: A receding horizon approach

In this article, we consider a receding horizon control of discrete-time state-dependent jump linear systems, particular kind of stochastic switching systems, subject to possibly unbounded random disturbances and probabilistic state constraints. Due to a nature of the dynamical system and the constraints, we consider a one-step receding horizon. Using inverse cumulative distribution function, we convert the probabilistic state constraints to deterministic constraints, and obtain a tractable deterministic receding horizon control problem. We consider the receding control law to have a linear state-feedback and an admissible offset term. We ensure mean square boundedness of the state variable via solving linear matrix inequalities off-line, and solve the receding horizon control problem on-line with control offset terms. We illustrate the overall approach applied on a macroeconomic system

Economic and environmental multiobjective optimization of a wind–solar–fuel cell hybrid energy system in the colombian caribbean region

A hybrid system was analyzed and optimized to produce electric energy in non-interconnected zones in the Colombian Caribbean region, contributing to the reduction of greenhouse gas emissions and the improvement in efficient energy management. A comparative analysis of the performance of hybrid was conducted using a proposed model, built with historical data for meteorological conditions, wind speed, and solar radiation. The model is integrated by a Southwest Wind Power Inc. wind turbine AIR 403, a proton-exchange membrane fuel cell (PEM), an electrolyzer, a solar panel, and a regulator based on proportional, integral, and derivative (PID) controllers to manipulate oxygen and hydrogen flow entering in the fuel cell. The transient responses of the cell voltage, current, and power were obtained for the demand of 200 W under changes in solar radiation and wind speed for each day of the year 2013 in different meteorological stations, such as Ernesto Cortissoz airport, Puerto Bolívar, Alfonso Lopez airport, and Simon Bolívar airport. Through the adjustment of the hydrogen and oxygen flow into the fuel cell, the maximum contribution of power generation from the fuel cell was presented for the Simon Bolívar airport in November with a value of 158.35 W (9.45%). Multiobjective design optimization under a Pareto diagram front is presented for each place studied to minimize the levelized cost of energy and CO2 emission, where the objective control variables are the number of panel and stack in the photovoltaic (PV) system and PEM

Multiobjective Optimization of a Plate Heat Exchanger in a Waste Heat Recovery Organic Rankine Cycle System for Natural Gas Engines

A multiobjective optimization of an organic Rankine cycle (ORC) evaporator, operating with toluene as the working fluid, is presented in this paper for waste heat recovery (WHR) from the exhaust gases of a 2 MW Jenbacher JMS 612 GS-N.L. gas internal combustion engine. Indirect evaporation between the exhaust gas and the organic fluid in the parallel plate heat exchanger (ITC2) implied irreversible heat transfer and high investment costs, which were considered as objective functions to be minimized. Energy and exergy balances were applied to the system components, in addition to the phenomenological equations in the ITC2, to calculate global energy indicators, such as the thermal efficiency of the configuration, the heat recovery efficiency, the overall energy conversion efficiency, the absolute increase of engine thermal efficiency, and the reduction of the break-specific fuel consumption of the system, of the system integrated with the gas engine. The results allowed calculation of the plate spacing, plate height, plate width, and chevron angle that minimized the investment cost and entropy generation of the equipment, reaching 22.04 m2 in the heat transfer area, 693.87 kW in the energy transfer by heat recovery from the exhaust gas, and 41.6% in the overall thermal efficiency of the ORC as a bottoming cycle for the engine. This type of result contributes to the inclusion of this technology in the industrial sector as a consequence of the improvement in thermal efficiency and economic viability

Actuator and sensor fault estimation based on a proportional-integral quasi-LPV observer with inexact scheduling parameters

© 2019. ElsevierThis paper presents a method for actuator and sensor fault estimation based on a proportional-integral observer (PIO) for a class of nonlinear system described by a polytopic quasi-linear parameter varying (qLPV) mathematical model. Contrarily to the traditional approach, which considers measurable or unmeasurable scheduling parameters, this work proposes a methodology that considers inexact scheduling parameters. This condition is present in many physical systems where the scheduling parameters can be affected by noise, offsets, calibration errors, and other factors that have a negative impact on the measurements. A H8 performance criterion is considered in the design in order to guarantee robustness against sensor noise, disturbance, and inexact scheduling parameters. Then, a set of linear matrix inequalities (LMIs) is derived by the use of a quadratic Lyapunov function. The solution of the LMI guarantees asymptotic stability of the PIO. Finally, the performance and applicability of the proposed method are illustrated through a numerical experiment in a nonlinear system.Peer ReviewedPostprint (author's final draft

Santander

Discurso pronunciado el 6 de mayo de 1940, al inaugurarse en Popayán la estatua del prócer. El autor elogia al "Hombre de las Leyes"; reflexiona sobre su participación en la construcción de la República y, asimismo, sobre la figura de bronce que es puesta en su honor; igualmente, presenta diversas facetas del perfil intelectual de Santader

Construcción de una plataforma de levitación electromagnética utilizando sensores infrarrojos

Hace años se trataba el magnetismo y la electricidad como fenómenos distintos y fueron estudiados por ciencias diferentes, sin embargo, esto cambió con el descubrimiento que realizó Christian Oersted, cuando observó que la orientación de la aguja de una brújula fue afectada al hacer circular corriente por un conductor cercano a ella. Desde entonces los estudios realizados por Oersted fueron en torno a demostrar que había una relación entre la electricidad y el magnetismo; él manifestó que las fuerzas magnéticas procedían de las fuerzas originadas entre las cargas eléctricas en movimiento. El electromagnetismo es la rama de la física que estudia los fenómenos eléctricos y magnéticos en una sola teoría, la cual demuestra que al circular una corriente eléctrica por un conductor, esta produce un campo magnético a su alrededor. Basados en la teoría electromagnética se realizó una plataforma de levitación, la cual consiste en generar un campo magnético producido por la circulación de corriente en una bobina e interactuar con el campo magnético producido por un imán de neodimio hasta dejar el imán suspendido en el aire sin soporte mecánico alguno. En el estudio de la levitación se pueden encontrar dos principios básicos: el principio de levitación por atracción y el principio de levitación por repulsión

Multi-Objective analysis of a CHP system using natural gas and biogas on the prime mover

With the aim of reducing operational costs and gas emissions in a Combined Heat and Power System (CHP), a type of biofuel is proposed as a product of a process using a biomass resource to replace other types of fossil fuels, and to be able to cover the average annual scale of power demand of 24 MWh/day from a metallurgical plant, and a thermal energy demand of 60 MWh/day. This study shows the behavior of gas emissions and economic analysis through the use of HOMER Pro software depending on the type of fuel selected. The proposed system consists of a set of electric generators (2MW in total) and a boiler with a cogenerative system connected to the gas outlet of the electric generators. The results of the simulation showed that the system working with natural gas presents a decrease of 5.66% in the annual operating cost concerning the system that works with biogas. However, the biogas system causes a 19.39% decrease in carbon dioxide production compared to the other systems