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Ma W.,Wuhan Naval University of Engineering
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2011

Power electronic technology is developing rapidly in recent years, and it is widely used in shipboard power systems. Typical applications of power electronics in naval ship power systems such as static excitation regulation in high speed induction machines, static power conversion systems, DC zonal electric distribution systems, and electric propulsion systems are proposed. Some suggestions are given about how to accelerate the development of power electronic technology.

Yan B.H.,Wuhan Naval University of Engineering
Annals of Nuclear Energy | Year: 2011

The laminar to turbulent transition process of pulsating flow in ocean environment is investigated with the theory of energy gradient. The effect of ocean environment on the flow breakdown position is weak. The effect of oscillating period on the laminar to turbulent transition increases with the increasing of oscillating period. The influence of ocean environment on the transition also increases with the increasing of oscillating amplitude. If the oscillating amplitude is very high, the traditional calculation method could not give a satisfactory prediction for the laminar to turbulent transition. © 2011 Elsevier Ltd. All rights reserved.

Yan B.H.,Wuhan Naval University of Engineering
Nuclear Engineering and Design | Year: 2011

The periodic large scale vortex structure is highly accounted for the local flow and heat transfer and turbulent mixing in rod bundles. In this paper, the mechanism of the periodic large scale structures is studied in terms of the vortex dynamics. The vortex structure in rectangular channels with different inlet velocities is also analyzed. It is found that the periodic large scale vortex structure exists in the rectangular channels with transverse vorticity gradient. The distribution of vorticity is strictly related with that of vortex structure. Copyright © 2011 Published by Elsevier B.V. All rights reserved.

Chang G.,China Institute of Technology | Chang G.,Wuhan Naval University of Engineering
IET Radar, Sonar and Navigation | Year: 2014

The independence of the process and observation noises is the prerequisite of many Kalman-type filters. However, the fact is that these two noises may be correlated with each other in actual applications. The filtering of the non-linear systems with cross-correlated process and observation noises at the same epoch is studied. First, a decorrelated scheme is introduced and a pseudo non-linear process equation is reconstructed in which the corresponding pseudo process noise is no longer cross-correlated with the observation noise; so a celebrated non-linear filter, that is, the unscented Kalman filter (UKF) can be used to filter the non-linear problem. Second, the (conditionally) linear substructure in the above non-linear system is exploited and a refined filter called marginal UKF is employed so as to reduce computational load without deteriorating the accuracy. The performance of the standard UKF for the original system equations, the standard and marginal unscented UKFs for the reconstructed system equation are compared in the simulation. From the results of the simulation, the theoretical statements are validated, and some interesting but not surprising phenomena are also founded, that is, the performance of the conventional filter actually does not degenerate, whereas that of the proposed filters become better when cross-correlation exists and increases. This phenomenon can be due to the fact that the proposed filters exploited the extra information buried in the cross-correlation, whereas the conventional filter fails to do so. © The Institution of Engineering and Technology 2013.

Yan B.H.,Wuhan Naval University of Engineering
Nuclear Engineering and Design | Year: 2013

A new lattice with non-uniform wall roughness and excellent heat transfer enhancement is introduced. The similar lattice with non-uniform wall thickness is also given in this paper. This kind of lattice could not only enhance the heat transfer and fluid mixing effectively but also avoid the disadvantages of tight lattice. The flow pulsation, vortex structure, flow and heat transfer in lattice were investigated with unsteady Reynolds Averaged Navier-Stokes simulation. The maximum heat transfer coefficient in the non-uniform wall roughness is about two times of that in traditional rod bundles. With the same power, the heat transfer could be increased by 40% compared to the traditional rod bundles in heat exchangers and nuclear systems. © © 2013 Elsevier B.V. All rights reserved.

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