Discriminación y redes sociales: Popularidad entre los estudiantes de bachillerato en Argentina

El objetivo de este trabajo es adquirir un mejor entendimiento del fenómeno de la popularidad de compañeros de clase durante la adolescencia y detectar señales de discriminación. En Argentina, estudiantes de secundaria seleccionan y clasifican a 10 compañeros de clase con los que les gustaría formar equipo. Se descubrió que los estudiantes físicamente atractivos y de alto rendimiento académico son altamente cotizados por sus compañeros de clase, pero sólo en planteles mixtos, lo que hace pensar que eso responde principalmente al emparejamiento. Otros rasgos, tales como el color de la piel, la nacionalidad y el nivel socioeconómico de los padres, no inciden en la popularidad entre los compañeros de clase, aunque el origen étnico y la formación académica de los padres son estadísticamente significativos en algunos casos. Da la impresión de que el tratamiento desigual basado en la raza, riqueza económica y nacionalidad que hay presente en otros entornos sociales de Argentina no se observa entre los adolescentes que asisten a la escuela.

Dead-Time compensators: A unified approach

IFAC Linear Time Delay Systems,Grenoble,France,1998This paper shows how most dead-time compensators can be considered as a particular case ofa proposed general control structure. The proposed structure can be tuned taking into account the performance and robustness ofthe closed-loop. The obtained controller is more general and allows better results than previous algorithms. In order to illustrate the results, some simulation examples are shown

Prediction for control

5th IFAC Conference on System Structure and Control 1998 (SSC'98), Nantes, France, 8-10 JulyThis paper shows that "optimal" controllers based on "optimal" predictor structures are not "optimal" in their closed loop behaviour and that predictors should be designed taking into account closed-loop considerations. This is first illustrated with a first order plant with delay. The ISE index is computed for two typical optimal controllers (minimum variance controller and generalized predictive controller) when a stochastic disturbance is considered. The results are compared to those obtained by the use of a non optimal PI controller that uses a non optimal Smith predictor and performs better than the optimal controllers for the illustrative example. A general structure for predictors is proposed. In order to illustrate the results, some simulation examples are shown.Ce papier montre que des lois de commandes "optimales" basees sur des structures predictives "optimales" ne sont pas "optimales" dans leur comportement en boucle fermee et que la synthese de predicteurs devrait prendre en compte des considerations de boucle fermee. Cela est d'abord illustre avec un systeme du premier ordre a retard. l'index ISE est calcule pour deux lois de commandes optimales typiques (loi de commande a variance minim ale et loi de commande predictive generalisee), quand une perturbation stochastique est consideree. Les resultats sont compares a. ceux obtenus avec un regulateur PI non optimal base sur un predicteur de Smith non optimal et sont, pour l'exemple illustratif, meilleurs que ceux obtenus avec un regulateur optimal. Vne structure generale de predicteur est proposee. Pour illustrer les resultats, des exemples de simulations sont montres

La economía de los trasplantes de organos: Los incentivos importan

El problema del faltante de órganos para trasplantes es grave en la mayoría de los países con programas desarrollados de trasplantes. En este ensayo resumo la investigación sobre el problema del faltante de órganos que desarrollamos de forma conjunta con Gary Becker de la Universidad de Chicago. Primero muestro la causa principal del faltante de órganos y el costo que impone el sistema actual sobre aquellos que esperan por un órgano. Luego presento una propuesta que desarrollamos con Gary Becker para resolver el problema de manera efectiva. Nuestra solución está basada en la utilización del mecanismo de los precios: Pagar por órganos. Con Becker mostramos que la introducción de incentivos monetarios para los donantes aumentaría la oferta de órganos suficientemente como para eliminar las largas colas de espera. Estos incentivos no aumentarían el costo de trasplantes en un porcentaje importante y lograrían eliminar la espera, aumentar la calidad de vida y reducir la cantidad de muertes de manera contundente. También analizo la efectividad de enfoques alternativos basados en el altruismo que han sido utilizados para intentar solucionar el problema, como ser el desarrollo del sistema de donaciones cruzadas (Kidney Paired Donation) y la adopción del sistema de consentimiento presunto para la procuración de órganos. Aún cuando los beneficios de eliminar el faltante de órganos y acabar con las muertes en la lista de espera son significativos, algunos se oponen a la propuesta de pagar por órganos. Los críticos afirman que el pago de órganos sería ineficaz, que sería inmoral porque se trata de la venta de partes del cuerpo humano y que los principals donantes serían personas pobres desesperadas, que podrían llegar a lamentar su decisión. En la última parte discuto sobre la “repugnancia” hacia la comercialización de órganos como una restricción al desarrollo del mercado

A Prediction approach to introduce dead-time process control in a basic control course

7TH IFAC SYMPOSIUM ON ADVANCES IN CONTROL EDUCATION. 21/06/2006. MADRIDThis paper presents a methodology to introduce the control of dead-time processes using a simple and intuitive predictive approach. A trivial solutionfor the control of a process with a dead-time is first proposed. From this strategythe idea of the predictor based controller is derived. Open-loop predictors andclosed-loop ones are then used to analyze the obtained solution. A simple tuningof the proposed structure for a first order plus dead-time process together with apolynomial approximation of the dead-time allows to derive apidcontroller. Thus,the approach based on the idea of prediction can be used to interpret the use of apidto control a dead-time process. It is illustrated how the performance of thepidcontroller is limited by the modelling error introduced in the approximation. Thepresented approach gives a measurement of the achievable performance. Severalsimulation examples illustrate the results.Ministerio de Ciencia y Tecnología DPI 2005-0456

Robust PID tuning. Application to a Mobile Robot Pathtraking problem.

IFAC Digital Control: Past,Present and Future of PlO Control.Terrassa.Spain.2000This paper presents a methodology for tuning PIDs considering the nominal performance and the robustness as control specifications. The synthesis procedure is similar to the Ziegler-Nichols method for PID controllers and can be easily used for industrial processes. As a workbench for testing the PID controller a mobile robot has been used. The path tracking problem of a mobile robot has been used as a workbench for testing the PID controller

A Robust Adaptive Dead-Time Compensator with Application to A Solar Collector Field

This paper describes an easy-to-use PI controller with dead-time compensation that presents robust behaviour and can be applied to plants with variable dead-time. The formulation is based on an adaptive Smith predictor structure plus the addition of a filter acting on the error between the output and its prediction in order to improve robustness. The implementation of the control law is straightforward, and the filter needs no adjustment, since it is directly related to the plant dead-time. An application to an experimentally validated nonlinear model of a solar plant shows that this controller can improve the performance of classical PID controllers without the need of complex calculations.Ministerio de Ciencia y Tecnología TAP95-37

Multi-sensor system using plastic optical fibers for intrinsically safe level measurements

A system for measuring liquid level in multiple tanks using optical fibe technology has been developed. Oil fiel service industry or any sector requiring liquid level measurements in flammabl atmospheres can be benefite from this intrinsically safe technology. The device used a single lens for the emitting and receiving fibe and it is based on amplitude variations as a function of the liquid distance and not in time of fligh or phase detection. Being the firs fiber-opti liquid level sensor with those characteristics for long ranges (>200 cm). A simple model to describe their behavior has been derived and tested on two prototypes. A Monte-Carlo method is used to fi the experimental data and obtain the model parameters. High accuracy between experimental data and fitte curve is obtained. The prototypes have a good linearity, better than 1.5% FS (full scale). Sensor heads are made of plastic optical fiber (POF) that are easy to handle, flexible and economical. They are excited by 650 nm lasers, housed in ST-connectors to obtain compact and rough prototypes. Optical multiplexing is used to increase the measuring safety area. Frequency division multiplexing is used to address each sensor head. A discussion about the influenc of tilts and aberrations is also included.Publicad

Advanced Control for Energy Management of Grid-Connected Hybrid Power Systems in the Sugar Cane Industry

This work presents a process supervision and advanced control structure, based on Model Predictive Control (MPC) coupled with disturbance estimation techniques and a finite-state machine decision system, responsible for setting energy productions set-points. This control scheme is applied to energy generation optimization in a sugar cane power plant, with non-dispatchable renewable sources, such as photovoltaic and wind power generation, as well as dispatchable sources, as biomass. The energy plant is bound to produce steam in different pressures, cold water and, imperiously, has to produce and maintain an amount of electric power throughout each month, defined by contract rules with a local distribution network operator (DNO). The proposed predictive control structure uses feedforward compensation of estimated future disturbances, obtained by the Double Exponential Smoothing (DES) method. The control algorithm has the task of performing the management of which energy system to use, maximize the use of the renewable energy sources, manage the use of energy storage units and optimize energy generation due to contract rules, while aiming to maximize economic profits. Through simulation, the proposed system is compared to a MPC structure, with standard techniques, and shows improved behavior.Ministerio de Economía y Competitividad CNPq401126/2014-5Ministerio de Economía y Competitividad CNPq303702/2011-7Ministerio de Economía y Competitividad DPI2016-78338-