Yanfeng Chen

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In this paper, the basic principle of space-voltage vector PWM (SVPWM) is presented. Due to back propagation neural networks (BP) based SVPWM controller have local optimization problem and lower training rate, a radial basis function neural networks (RBF) controller based SVPWM is proposed. Using Matlab/Simulink together with Neural Network Toolbox, we(More)
Morse theory was originally due to M arston M orse [5]. It gives us a method to study the topology of a manifold using the information of the critical points of a Morse function defined on the manifold. Based on the same idea, Morse homology was introduced by T hom, Smale, M ilnor, and W itten in various forms. This paper is a survey of some work in this(More)
As a combination of mobile e-commerce and traditional tourism, the mobile travel services have been being tested on part of the scenic areas of the country in recent years. It achieved worthy results and provided a lot of convenience for our visitors. With the investigation and method of PCA (principal component analysis), we concluded that demands of(More)
The characteristic of PLL (phased-locked Loop) has very important influence on the performance of UPS (uninterruptible power supply). Sometimes, false phase can be locked by the classical PLL circuit based on detecting the zero-crossing points due to the wrong phase information under distorted utility conditions. This paper proposes a novel PLL which(More)
Recent experiments show video games have a range of positive cognitive effects, such as improvement in attention, spatial cognition and mental rotation, and also overcoming of cognitive disabilities such as fear of flying. Further, game environments are now being used to generate scientific discoveries, and bring about novel phenomenological effects, such(More)
ACKNOWLEDGEMENTS The doctor of philosophy degree is generally regarded as the pinnacle of individual academic achievement, but this is a common misconception. A Ph. D. is most certainly not a solo effort. The work that I present in this dissertation would not and could not have been completed without the assistance of many wonderful scientists (and(More)
Ontology languages and corresponding query languages play key roles for representing and processing information about the real world for the emerging Semantic Web. Efforts have been made to develop various ontology languages. Each ontology language provides different expressive power and also computational complexity for reasoning. Ontology query languages(More)
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