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Direct adaptive regulation of unknown nonlinear systems with analysis of the model order problem
Dimitrios Theodoridis, Yiannis Boutalis, Manolis Christodoulou
Front. Inform. Technol. Electron. Eng., 2011, 12(1): 1-16.
https://doi.org/10.1631/jzus.C1000224
A new method for the direct adaptive regulation of unknown nonlinear dynamical systems is proposed in this paper, paying special attention to the analysis of the model order problem. The method uses a neuro-fuzzy (NF) modeling of the unknown system, which combines fuzzy systems (FSs) with high order neural networks (HONNs). We propose the approximation of the unknown system by a special form of an NF-dynamical system (NFDS), which, however, may assume a smaller number of states than the original unknown model. The omission of states, referred to as a model order problem, is modeled by introducing a disturbance term in the approximating equations. The development is combined with a sensitivity analysis of the closed loop and provides a comprehensive and rigorous analysis of the stability properties. An adaptive modification method, termed ‘parameter hopping’, is incorporated into the weight estimation algorithm so that the existence and boundedness of the control signal are always assured. The applicability and potency of the method are tested by simulations on well known benchmarks such as ‘DC motor’ and ‘Lorenz system’, where it is shown that it performs quite well under a reduced model order assumption. Moreover, the proposed NF approach is shown to outperform simple recurrent high order neural networks (RHONNs).
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Cartoon capture by key-frame based contour tracking
Chun-luan Zhou, Jun Xiao
Front. Inform. Technol. Electron. Eng., 2011, 12(1): 36-43.
https://doi.org/10.1631/jzus.C1000123
Traditional cartoons have been widely used in entertainment, education, and advertisement. Thus, a large amount of cartoon data is available. In this paper, we propose a new technique for capturing the motion of a character in an existing cartoon sequence. This technique tracks the contours of the cartoon character in the sequence, and key frames are used to guide the tracking. We model contour tracking as a space-time optimization problem in which an energy function including both temporal and spatial constraints is defined. First, the user labels the contours of the character on the key frames. Then, the contours on the intermediate frames are tracked by minimizing the energy function. The user may need to interactively adjust the tracking result and restart the optimization process to refine the result. Finally, an edge snapping algorithm is applied to make the tracking result more precise. Experiments show that our technique works effectively.
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Index and retrieve the skyline based on dominance relationship
Chang XU, Li-dan SHOU, Gang Chen, Yun-jun Gao
Front. Inform. Technol. Electron. Eng., 2011, 12(1): 62-75.
https://doi.org/10.1631/jzus.C0900003
In multi-criterion decision making applications, a skyline query narrows the search range, as it returns only the points that are not dominated by others. Unfortunately, in high-dimensional/large-cardinal datasets there exist too many skyline points to offer interesting insights. In this paper, we propose a novel structure, called the dominance tree (Do-Tree), to effectively index and retrieve the skyline. Do-Tree is a straightforward and flexible tree structure, in which skyline points are resident on leaf nodes, while the internal nodes contain the entries that dominate their children. As Do-Tree is built on a dominance relationship, it is suitable for the retrieval of specified skyline via dominance-based predicates customized by users. We discuss the topology of Do-Tree and propose the construction methods. We also present the scan scheme of Do-Tree and some useful queries based on it. Extensive experiments confirm that Do-Tree is an efficient and scalable index structure for the skyline.
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8 articles
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