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Dai Y.,Beijing University of Posts and Telecommunications | Wang R.,China Academy of Information and Communications Technology | Yin F.,Beijing University of Posts and Telecommunications | Dai J.,Beijing University of Posts and Telecommunications | And 3 more authors.
Optics Express | Year: 2015

Multiple sidemodes have been observed in a coupled optoelectronic oscillator (COEO) when the contained actively mode-locked fiber ring laser employs erbium-doped fiber (EDF). We propose that such sidemodes can be suppressed significantly by an optical pulse power feedforward scheme, through which the mode-locked optical pulse is reversely intensity-modulated by itself, resulting in a fast power limiting. Experimentally we show that sidemodes are suppressed as much as 40 dB in a 10-GHz COEO. The additional noise induced by the power feedforward technique is analyzed numerically. We show that for a COEO with a typical cavity length, the feedforward contribution to final single-side band (SSB) noise is minor and neglectable. © 2015 Optical Society of America. Source

Wei J.,Nanjing University of Aeronautics and Astronautics | Zhang F.,Nanjing University of Aeronautics and Astronautics | Pan S.,Nanjing University of Aeronautics and Astronautics | Yu L.,Wuhan Electronic Information Institute
European Microwave Week 2015: "Freedom Through Microwaves", EuMW 2015 - Conference Proceedings; 2015 45th European Microwave Conference Proceedings, EuMC | Year: 2015

A compact scheme for stable frequency dissemination over optical fiber is proposed and demonstrated. A standard signal in the center station is delivered to the remote end without any assistant signal source. The frequency of the received signal is the same as the signal source in the center station. A proof-of-concept experiment is performed. A 6-GHz standard signal is transmitted in a 20-km fiber. The phase jitter of the transmission was reduced from more than 41 ps to less than 1.17 ps. © 2015 EuMA. Source

Peng X.-N.,Hubei University | Wang Y.-L.,Wuhan Electronic Information Institute | Wang H.,Hubei University
Chinese Physics Letters | Year: 2015

The time-dependence evolution of the extinction spectra of the silver nanoplates is studied to analyze the underlying physical mechanism of the growth process. As the synthesis cycles increase, the wavelength of the absorption peak is first blue-shifted and then is followed by the red shift, attributing to the mode alteration of the longitudinal surface plasmon resonance of the silver nanoplates. The capping agents are also optimized for the convenient and speedy growth of the large integrated Ag nanostructure. These observations expand the comprehensive understanding of plasmon resonance of the Ag nanoplates, and give a better manipulation of their applications in the plasmonic nanodevices. © 2015 Chinese Physical Society and IOP Publishing Ltd. Source

Chen B.,Wuhan University | Chen Y.,Wuhan University | Chen Y.,Wuhan Electronic Information Institute | Tian C.,Wuhan University | And 3 more authors.
IEEE Transactions on Power Electronics | Year: 2015

This paper focuses on analysis and suppression of circulating harmonic currents in a modular multilevel converter (MMC) considering the impact of dead time in medium-voltage applications. A continuous equivalent model of the MMC containing two ideal transformer models is presented. Using this model, the impact of a harmonic voltage upon the dc side is analyzed and the production mechanism of circulating harmonic currents is elucidated. At the same time, the impact of dead time and insulated gate bipolar transistor (IGBT) voltage drop (DTVD) is studied, which indicates that capacitor voltages, output harmonics, and circulating harmonic currents are influenced. Based on this analysis, an open-loop control strategy to suppressing circulating harmonic currents caused by the output current and DTVD is presented. Finally, all these conclusions are verified using a simulation platform with 14 modules per arm fed by a 14-kV dc voltage source and a downscaled experimental platform with four modules per arm fed by a 560-V dc voltage source. © 1986-2012 IEEE. Source

Chen L.,Wuhan Electronic Information Institute | Liu J.M.,Wuhan Electronic Information Institute | Ouyang J.M.,Wuhan Finance School
Applied Mechanics and Materials | Year: 2014

This paper proposes a multi-thread-memory particle swarm optimization (MTM-PSO) for dynamic optimization problems (DOPs). It introduces multi-thread memory to multi-swarm approaches to deal with DOPs. External memory and multi-swarm approaches are adopted. The best particles near the peaks in each environment are saved in the memory according to storage strategy of update and implement. Multi-thread memory makes full use of local and global optima found in each environment. It makes the good information in the previous evolution transfer to the current population adequately. Using the multi-thread memory and its storage strategy, the particles in the memory are always the best information of local and global optima found until in the current envionment. The information will benefit the future evolution. Experiments on the moving peak benchmark (MPB) for different numbers of peaks testiy MTM-PSO has better performance than dynamic optimization algorithms only with multi-swarm approach. © (2014) Trans Tech Publications, Switzerland. Source

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