Meng Bai

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Three new dihydroisocoumarin penicimarins G-I (1-3), together with one known dihydroisocoumarin (4) and three known meroterpenoids (5-7), were obtained from a fungus Penicillium citrinum isolated from the mangrove Bruguiera sexangula var. rhynchopetala collected in the South China Sea. Their structures were elucidated by the detailed analysis of(More)
In this paper we study the two-phase size-structured population model with infinite states-at-birth and distributed delay in birth process. The model distinguishes individuals by two different status: the 'reproductive' stage and the 'nonreproductive' stage. We establish the well-posedness for this model and show that the solution of this model exhibits(More)
Yaw dynamic model of a miniature unmanned helicopter is needed to develop for heading control. A yaw dynamic model is deduced based on miniature unmanned helicopter characteristics in hover. Different from a large helicopter, the yaw damping system of a miniature helicopter is realized through the negative feedback of helicopter heading rate, which is(More)
The dynamic model of a miniature unmanned helicopter is needed to develop for autonomous helicopter flight. A subspace identification method for the roll and pitch coupling model is proposed. The roll and pitch coupling model of a hovering miniature unmanned helicopter is deduced to obtain an identification model structure for use in the subspace method.(More)
For SINS/GPS integrated navigation system with unknown measurement noise covariance matrix, adopting the conventional Kalman filtering approach to estimate the navigation system errors will lead to a large state estimation error or even make the filter diverge. To solve this problem, an adaptive sequential Kalman filter is presented, in which the(More)
Text contained in images and video frames provide an important clue for content based images and video indexing. However, it is difficult to segment text from images with complex background. This paper proposes a new proposal for text segmentation from images with complex background based on Markov random field. Experimental results demonstrate the(More)
To detect text from an image with a different background, an adaptive text detection method based on image complexity analysis is proposed. Before text detection, this approach adopts an image complexity analysis step to classify image complexity into three categories: low complexity, middle complexity and high complexity. Then images with different(More)