Suchergebnisse

The aim of this paper is to present a simple 3D computational model of a polymer electrolyte membrane fuel cell (PEMFC) that simulates over time the heat distribution, energy, and mass balance of the reactant gas flows in the fuel cell including pressure drop, humidity, and liquid water. Although this theoretical model can be adapted to any type of PEMFC, for verification of the model and to present different analysis it has been adapted to a single cell test fixture. The model parameters were adjusted through a series of experimental tests and the model was experimentally validated for a well-defined range of operating conditions: H2/air O2 as reactants, flow rates of 0.5-1.5 SLPM, dew points and cell temperatures of 30-80 °C, currents 0-5 A and with/without water condensation. The model is especially suited for the analysis of liquid water condensation in the reactant channels. A key finding is that the critical current at which liquid water is formed is determined at different flows, temperatures, and humidity. ; This work was supported by the project 'Avances en el modelo y diseño de controladores para sistemas basados en pila de combustible PEM' (4800). ; Funded by: Spanish Government. Grant Number: CICYT DPI2007-62966 and Spanish Government. Grant Number: CICYT DPI2004-06871. ; Peer Reviewed

This paper presents a distributed method for navigating a team of robots in formation in 2D and 3D environments with static and dynamic obstacles. The robots are assumed to have a reduced communication and visibility radius and share information with their neighbors. Via distributed consensus the robots compute (a) the convex hull of the robot positions and (b) the largest convex region within free space. The robots then compute, via sequential convex programming, the locally optimal parameters for the formation within this convex neighborhood of the robots. Reconfiguration is allowed, when required, by considering a set of target formations. The robots navigate towards the target collision-free formation with individual local planners that account for their dynamics. The approach is efficient and scalable with the number of robots and performs well in simulations with up to sixteen quadrotors. ; United States. Office of Naval Research (pDOT N00014-12-1-1000) ; United States. Army Research Laboratory (Grant W911NF-08-2-0004) ; Boeing Company ; Singapore-MIT Alliance for Research and Technology Center (Future of Urban Mobility Project) ; Spanish Government (Project DPI2012-32100) ; Spanish Government (Project DPI2015-69376-R) ; Spanish Government (Project CUD2013-05) ; Spanish Government (Grant CAS14/00205)