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Dempster-Shafer证据理论在水下多源目标识别领域有着广泛而重要的应用, 但经典的证据理论在融合高度冲突的证据时往往会导致一些反常理的结果, 如Zadeh冲突悖论。针对这一问题,综合考虑证据体之间的冲突程度和支持程度,提出一种证据异常度的概念并对原始证据集进行异常检测,基于检测结果对原始证据体进行权重分配,引入全集项,修正证据源。在保持Dempster组合规则不变的前提下,进行有效的证据预处理,实验仿真结果验证了算法的有效性。证明对证据体进行有效的修正,可以改进经典证据理论的缺点,达到更好的融合结果。 相似文献
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针对已有的基于经典粗糙集理论的组合预测单项模型选择方法存在的问题与不足,引入邻域粗糙集理论加以改进.首先采用kmeans算法对决策表进行适应性改进,使其符合邻域粗糙集的理论框架;然后,根据不同属性集中对应属性值的分布范围对每个属性集分别设置不同的邻域半径,使粒化结果更为科学合理;最后,结合均方根误差构造出新的属性重要度... 相似文献
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The effects of two parallel porous walls are investigated, consisting of the Darcy number and the porosity of a porous medium, on the behavior of turbulent shear flows as well as skin-friction drag. The turbulent channel flow with a porous surface is directly simulated by the lattice Boltzmann method (LBM). The Darcy-Brinkman- Forcheimer (DBF) acting force term is added in the lattice Boltzmann equation to simu- late the turbulent flow bounded by porous walls. It is found that there are two opposite trends (enhancement or reduction) for the porous medium to modify the intensities of the velocity fluctuations and the Reynolds stresses in the near wall region. The parametric study shows that flow modification depends on the Darcy number and the porosity of the porous medium. The results show that, with respect to the conventional impermeable wall, the degree of turbulence modification does not depend on any simple set of param- eters obviously. Moreover, the drag in porous wall-bounded turbulent flow decreases if the Darcy number is smaller than the order of O(10-4) and the porosity of porous walls is up to 0.4. 相似文献
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