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Xie X.D.,Hubei University of Arts and Science | Xie X.D.,University of Manitoba | Wang Q.,University of Manitoba | Wu N.,University of Manitoba
International Journal of Engineering Science | Year: 2014

An ocean wave energy harvester from the transverse wave motion of water particles is developed by the piezoelectric effects. The harvester is made of two horizontal cantilever plates attached by piezoelectric patches and fixed on a vertical rectangular column. To describe the energy harvesting process, a mathematical model is developed to calculate the output charge and voltage from the piezoelectric patches according to the Airy linear wave theory and the elastic beam model. The influences on the root mean square (RMS) of the generated power from the piezoelectric patches, such as the ocean depth, the harvester location under the ocean surface, the length of the cantilevers, the wave height, and the ratio of wave length to ocean depth, are discussed. Results show that the RMS increases with the increase in the length of cantilevers and the wave height, and decrease in the distance of the ocean surface to the cantilevers and the ratio of the wave length to ocean depth. As a result, an optimum ocean depth is obtained to achieve a maximum RMS at different harvester locations under the ocean surface. A value of the power up to 30 W can be realized for a practical transverse wave with the values of the ocean depth, wave length, wave height and harvester location under the ocean surface to be 10.6 m, 21.2 m, 4 m, and -2 m, respectively. This research develops a novel technique leading to efficient and practical energy harvesting from transverse waves by piezoelectric energy harvesters that could be easily fixed on an offshore platform. © 2014 Elsevier Ltd. All rights reserved. Source


Xie X.D.,Hubei University of Arts and Science | Wang Q.,University of Manitoba | Wu N.,University of Manitoba
International Journal of Engineering Science | Year: 2014

A ring piezoelectric harvester excited by magnetic forces with high excitation frequencies is developed. The harvester is made of a concentric outer ring stator and an inner ring rotator. The stator ring is made of a series of discrete piezoelectric patches with a rectangular shape surface mounted by magnetic ring slabs with the same size. All the piezoelectric patches and the magnetic slabs are placed on an aluminum ring. The rotator ring is made of a serious of magnetic rectangular slabs mounted on an aluminum ring with the exact size of the corresponding piezoelectric patches on the stator. Because of periodic magnetic forces between the stator ring and the rotator ring, a compression is induced to the piezoelectric patches leading to an electric charge for energy harvesting. To describe the energy harvesting process, a mathematical model is used to calculate the output charge and voltage from the piezoelectric patches. The influences of the size of the piezoelectric harvester and the rotating speed of the rotator ring on the root mean square of the generated electric power are discussed. Our results show that a power up to 5274.8 W can be realized for a practical design of the harvester with a radius around 0.5 m. This research develops a novel technique for an efficient and practical energy harvesting from the developed ring piezoelectric energy harvesters. © 2014 Elsevier Ltd. All rights reserved. Source


Yin X.,Huazhong University of Science and Technology | Hu S.,Hubei University of Arts and Science
Asian Journal of Control | Year: 2013

This paper is devoted to the consensus protocol design for a set of agents with fractional-order uncertainty dynamics where the fractional order α satisfies 0 < α < 2. For multi-agent systems (MASs) with fixed undirected topology, a distributed static output feedback protocol is proposed with an undetermined system matrix. Based on model transformation and fractional-order stability theory, sufficient conditions are derived to ensure the consensus of MASs in terms of linear matrix inequalities (LMIs). Finally, a simulation example is employed to validate the effectiveness of the proposed consensus protocol. © 2013 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society. Source


Yin X.,Huazhong University of Science and Technology | Yue D.,Nanjing University of Posts and Telecommunications | Hu S.,Hubei University of Arts and Science
Journal of the Franklin Institute | Year: 2013

This paper investigates the consensus problem for a set of discrete-time heterogeneous multi-agent systems composed of two kinds of agents differed by their dynamics. The consensus control is designed based on the event-triggered communication scheme, which can lead to a significant reduction of the information communication burden in the multi-agent network. Meanwhile, only the communication between the agent and its local neighbors is needed, therefore, the designed control is essentially distributed. Based on the Lyapunov functional method and the Kronecker product technique, a sufficient condition is obtained to guarantee the consensus of heterogeneous multi-agent systems in terms of linear matrix inequality (LMI). Simulation results illustrate the effectiveness of the developed theory in the last. Source


Yin X.,Huazhong University of Science and Technology | Yue D.,Huazhong University of Science and Technology | Hu S.,Hubei University of Arts and Science
IET Control Theory and Applications | Year: 2013

This study is devoted to the consensus protocols design for a set of fractional-order heterogeneous agents, which is composed of two kinds of agents differed by their dynamics and the fractional-order a satisfies 0 < α < 2. Distributed state feedback consensus protocols are constructed for the two kinds of agents, respectively. Based on the Kronecker product technique and the fractional-order stability theory, sufficient conditions are derived to ensure the consensus of heterogeneous multi-agent systems in terms of linear matrix inequalities (LMIs). These can be solved numerically by LMI toolbox in Matlab. Finally, a simulation example is employed to validate the effectiveness of the theoretical results. © The Institution of Engineering and Technology 2013. Source

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