Convergence of martingale solution to slow-fast systems with jumps modulated by Markovian switching

This paper investigates the convergence of martingale solutions to slow-fast systems with jumps modulated by Markovian switching on weakly irreducible class. The key point here is to deals with slow-fast systems and two-time-scale Markovian switching simultaneously, while averaging on the slow component requires two invariant measures respectively due to the coexistence of the fast component and Markovian switching. We first investigate the slow-fast systems modulated by Markovian chains with single weakly irreducible class, and the existence and uniqueness of the solution will be proved. Then weak convergence is presented based on tightness and the exponential ergodicity of the fast component with the martingale method, where the appropriate perturbed test functions plays a decisive role in processing. Finally we extend results to the case of the multiple irreducible class

An aerodynamic analysis of a novel small wind turbine based on impulse turbine principles

This document is the Accepted Manuscript of the following article: Pei Ying, Yong Kang Chen, and Yi Geng Xu, ‘An aerodynamic analysis of a novel small wind turbine based on impulse turbine principles’, Renewable Energy, Vol. 75: 37-43, March 2015, DOI: https://doi.org/10.1016/j.renene.2014.09.035, made available under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License CC BY NC-ND 4.0 http://creativecommons.org/licenses/by-nc-nd/4.0/The paper presents both a numerical and an experimental approach to study the air flow characteristics of a novel small wind turbine and to predict its performance. The turbine model was generated based on impulse turbine principles in order to be employed in an omni-flow wind energy system in urban areas. The results have shown that the maximum flow velocity behind the stator can be increased by 20% because of a nozzle cascade from the stator geometry. It was also observed that a wind turbine with a 0.3 m rotor diameter achieved the maximum power coefficient of 0.17 at the tip speed ratio of 0.6 under the wind velocity of 8.2 m/s. It was also found that the power coefficient was linked to the hub-to-tip ratio and reached its maximum value when the hub-to-tip ratio was 0.45. It is evident that this new wind turbine has the potential for low working noise and good starting feature compared with a conventional horizontal axis wind turbine.Peer reviewedFinal Accepted Versio