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Capacitor-current-feedback active damping is an effective method to suppress the LCL-filter resonance in grid-connected inverters. However, due to the variation of grid impedance, the LCL-filter resonance frequency will vary in a wide range, which challenges the design of the capacitor-current-feedback coefficient. Moreover, if the resonance frequency is(More)
Due to the significance of extracting the grid voltage information, the grid synchronization system plays an important role in the control of grid-connected power converters, and various grid voltage synchronization schemes have been proposed. This paper adopts the complex-vector-filter method (CVFM) to analyze the grid synchronization systems. With this(More)
Data from Landsat ETM+ images, meteorological records, digital elevation mode data and other statistical data were used to extract wetland-related information for the Heilongjiang River Basin, China, an area significantly affected by global climate change. Based on a pressure–state–response conceptual model, an integrated assessment index was constructed.(More)
To represent the textual knowledge more expressively, a kind of semanticbased graph structure is proposed, in which more semantic and ordering information among terms as well as the structural information of the text are incorporated. Such model can be constructed by extracting representative terms from texts and their mutually semantic relationships.(More)
Web page content extraction is a key step for knowledge acquisition from the Internet. The physical layout of Web pages is always composed of useful information, advertising links and images. So how to extract the right content and filter out irrelevant information is an important work. According to the different properties between content nodes and(More)
In this paper, we propose an improved information retrieval model, where the integration of modification-words and head-words is introduced into the representation of user queries and the traditional vector space model. We show how to calculate the weights of combined terms in vectors. We also propose a new strategy to construct the thesaurus in a fuzzy way(More)