Hopfield networks: from optimization to adaptive control

This paper proposes an adaptative control algorithm, which is designed by adding a parametric identification method to a non-linear controller. The identification module is built upon the Hopfield neural network, resulting in an unconventional network with time-varying weights and biases. The convergence of the estimations of the parameters of a dynamical system was proved in previous work, as long as the system inputs can be freely manipulated to provide persistent excitation. Henceforth the behaviour of the closed-loop system, when the inputs result from the controller equations, is here analyzed in order to assess both the tracking performance of the full adaptive controller and the identification ability of the neural estimator. The algorithm is applied to an idealized robotic system with two joints, whose positions and velocities are required to follow, as closely as possible, a prescribed reference trajectory. The simulation results show a satisfactory control performance, since the demanded trajectory is almost accurately followed. The estimated values also converge to the correct parameters, as long as the controller provides sufficiently rich signals to the system. The results are similar to a conventional least-squares adaptive controller, with a much lower computational cost.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

On Coalition Formation with Heterogeneous Agents

We propose a framework to analyze coalition formation with heterogeneous agents. Existing literature defines stability conditions that do not ensure that, once an agent decides to sign an agreement, the enlarged coalition is feasible. Defining the concepts of refraction and exchanging, we set up conditions of existence and enlargement of a coalition with heterogeneous agents. We use the concept of exchanging agents to give necessary conditions for internal stability and show that refraction is a sufficient condition for the failure of an enlargement of the coalition. With heterogeneous agents we can get a situation where a group of members of an unstable coalition does not deviate, neither within the coalition nor within the extended coalition. Hence, the possibilities of agreement are richer than in the standard analysis with homogeneous agents. Examples of industrial economics are used for illustration, and an application to climate change negotiations is discussed in more detail.Heterogeneity, Coalition, Exchanging, Refraction, Global Externalities

Algunos aspectos de la relación entre el comercio y el medio ambiente

Este trabajo estudia las interrelaciones entre el comercio y el medio ambiente a través de dos cuestiones: si el librecambismo, y el consiguiente aumento del comercio, es positivo desde el punto de vista ambiental, y si es legítimo utilizar instrumentos de política comercial para proteger el medio ambiente

Bargaining with Non-Monolithic Players

This paper analyses strategic bargaining in negotiations between non-monolithic players, i.e. agents starting negotiations can split up in smaller entities during the bargaining process. We show that the possibility of scission in the informed coalition implies that it loses its information advantages. We also show that when the possibility of a scission exists the uninformed player does not focus on his or her beliefs about the strength of the informed coalition but on the proportion of weak/strong players within this coalition. Finally, our results show that the possibility of a scission reduces the incentives for the leader to propose a high offer to ensure a global agreement. We apply this framework to international negotiations on global public goods and to wage negotiations.Strategic bargaining, Non-monolithic players, Scission, Noncooperative game-theory

North-South Climate Change Negotiations: a Sequential Game with Asymmetric Information

This article determines the conditions under which the Southern countries should act together, or separately, while negotiating with the North about climate change policy and about the conditions for future Southern engagement. The paper models the international negotiations with complete and with asymmetric information in a dynamic framework. Results show that, depending on their characteristics, the different players can obtain benefits delaying the moment of the agreement.Bargaining theory, asymmetric information, climate change, international cooperation

Implementación de arquitectura de control 3T en la RoboCup Small Size League : formación de defensa

La RoboCup es un proyecto internacional que aparece en 1997 para promover, a través de competencias integradas por robots autónomos, la investigación y educación sobre inteligencia artificial. Esta se compone de distintos tipos de competiciones que tratan de conseguir una investigación sobre el comportamiento, coordinación y trabajo en equipo de los robots. El objetivo principal de este proyecto es la implementación de una arquitectura 3T para los robots de la RoboCup SSL y desarrollar algunas habilidades básicas para el control de los robots y de esta forma asentar una base sobre la que trabajar en el futuro. Además, se realizan pruebas del trabajo realizado tanto en un simulador como en un robot real para comprobar el correcto funcionamiento de la arquitectura y comparar la ejecución en un entorno simulado y en un entorno real. __________________________________________________________________________________________________________________________________The RoboCup is an international Project that appears in 1997 to promote, through integrated skills for autonomous robots, research and education in artificial intelligence. This is composed of different types of competitions that seek to achieve behavioral research, coordination and teamwork of the robots. The main objective of this project is the implementation of a 3T architecture for the robots of the RoboCup SSL and develop some basic skills to control robots and thus laid a foundation on which to work in the future. In addition, tests are done the work done both in a simulator and in a real robot to verify the proper functioning of the architecture and compare the performance in a simulated environment and real environment.Ingeniería Informátic

Valoración económica del uso múltiple de un espacio natural : análisis aplicado en los pinares e la sierra de Guadarrama

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Económicas y Empresariales, Departamento de Economía Aplicada I, leída el 18-05-2001.Depto. de Economía Aplicada, Estructura e HistoriaFac. de Ciencias Económicas y EmpresarialesTRUEProQuestpu

Spatial valuation of forests' enviromental assets: an application to Andalusian Silvopastoral farms

We develop a model that estimates spatially allocated environmental asset values for the simultaneous provision of seven ecosystem services. We examine the effect of heterogeneous spatial and economic factors on asset figures, and identify potential forestry abandonment problems when continuing with forestry activity becomes unprofitable for the landowner. Our results show a relevant spatial variability according to forest species distribution and structure. We examine potential trade-offs among silvopastoral provisioning services, water, and carbon sequestration services. Results forecast the abandonment of forestry activity and quantify the significant impact of discount rates and prices on asset values

Synthesis and Characterization of New Layered Double Hydroxide-Polyolefin Film Nanocomposites with Special Optical Properties

In this study, we have synthesized new double layered hydroxides to be incorporated to low density polyethylene thermoplastic matrix. These new composites present promising applications as materials to build greenhouses due to the enhancement of their optical properties. A characterization of the modified nanoclay has been performed by means of X-ray fluorescence (XRF), X-ray Diffraction (XRD), Thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR). We have prepared a series of polyolefin-based films to evaluate the effect of the addition of a whitening agent (disodium 2,20 -((1,10 -biphenyl)-4,40 -diyldivinylene)bis(benzenesulfonate)), the modified hydrotalcite-like material and a commercial dispersant. The rheological and mechanical characterization of the films have proved that the inclusion of the modified-layered double hydroxides (LDHs) do not substantially affect the processing and mechanical performance of the material. On the other hand, optical properties of the nanocomposites are improved by reducing the transmission in the UVA region.This research was funded by CETEC (Project 5865/19IMMF-C) and “Este trabajo es resultado de la actividad desarrollada en el marco del Programa de Ayudas a Grupos de Excelencia de la Región de Murcia, de la Fundación Séneca, Agencia de Ciencia y Tecnología de la Región de Murcia (grant #19877/GERM/15)”. Authors thank Carlos Gracia from TA Instruments for technical support

Efectividad del uso de diferentes tipos de feedback en la rehabilitación de sujetos con inestabilidad crónica de tobillo: una revisión sistemática

58 p.Introducción: La inestabilidad crónica de tobillo (ICT) afecta entre un 20- 70% de las personas que han sufrido un esguince de tobillo. Para su tratamiento habitualmente se realizan ejercicios de equilibrio, fuerza muscular, rango articular y propiocepción. Hay evidencia de que los tratamientos tradicionales no son suficientes para dejar de percibir ICT. Por lo cual se están utilizando feedbacks, sin embargo, aún falta más información para conocer la efectividad que puede tener para ICT. Objetivo: Determinar la efectividad de los diferentes tipos de feedback en la rehabilitación de sujetos con ICT. Método: Se realizó una revisión sistemática de literatura en 3 bases de datos Pubmed, Scopus y Web of Science, entre los años 2017 a 2022. Se seleccionaron 10 artículos sobre el uso de feedback en la ICT. Resultados: El feedback más utilizado fue el visual. Además, la mayoría de los artículos solo evaluan una sesión con feedback. Existe alta heterogeneidad entre los tipos de feedback y variables. Conclusiones: No es posible concluir que el uso de feedback tiene efectos favorables para la rehabilitación de sujetos con ICT, debido a la heterogeneidad de feedbacks. // ABSTRACT: Introduction: Chronic ankle instability (CAI) affects between 20-70% of people who have suffered an ankle sprain. For its treatment, balance, muscle strength, joint range and proprioception exercises are usually performed.There is evidence that traditional treatments are not enough to stop perceiving CAI. Therefore, feedbacks are being used, however, more information is still needed to know the effectiveness that it can have for CAI. Objective: To determine the effectiveness of the different types of feedback in the rehabilitation of subjects with CAI. Method: A systematic review of the literature was carried out in 3 Pubmed, Scopus and Web of Science databases, between the years 2017 and 2022. 10 articles on the use of feedback in CAI were selected. Results: The most commonly used feedback was visual. In addition, most of the articles only evaluate one session with feedback. There is high heterogeneity among the types of feedback and variables. Conclusions: It is not possible to conclude that the use of feedback has favorable effects for the rehabilitation of subjects with ICT, due to the heterogeneity of feedbacks