Based on the gray-level change characteristic between two successive video frames, gray information are broadly used for the detection of moving objects. However, the method will lose a lot of useful color information. In this paper, we propose a new approach to detect moving objects in the color space. The method utilizes the space vector difference to obtain a difference map between current video frame and background model. Then, by analyzing characteristic of the difference map histogram, an adaptive threshold is automatically calculated. The threshold can effectively separate moving objects and remove various significant noises in current video frame. The experimental results on several standard sequences demonstrate the efficiency and the high accuracy of the proposed method.
3-D single-phase flow field in 5×5 rod bundles with spacer grids was studied by numerical method. Using hybrid grids technique, SST k-ω model and SIMPLEC algorithm, the Reynolds averaged mass conservation and momentum conservation equations were solved, and the pressure and velocity field were obtained. The simulation results show that the spacer grids leads to intense lateral flow in rod bundles channel, and it submitted parabola distributing raw; axial velocities were distributed uniformly in the channel; drag coefficient decreased as inlet Reynolds number increased. Calculated results agreed with experiment data well, it shows that numerical methods employed in this paper is suitable to study flow field in 5×5 rod bundles.
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