为了对灰度不均匀图像进行分割,结合图像的局部和全局信息,提出基于加权L^(1)-L^(2)拟合能量项的模糊活动轮廓图像分割(fuzzy active contour based on weighted L^(1)-L^(2) fitting energy for image segmentation,FAWFE)模型。首先,...为了对灰度不均匀图像进行分割,结合图像的局部和全局信息,提出基于加权L^(1)-L^(2)拟合能量项的模糊活动轮廓图像分割(fuzzy active contour based on weighted L^(1)-L^(2) fitting energy for image segmentation,FAWFE)模型。首先,利用模糊隶属度函数,基于图像局部和全局信息构建混合模糊拟合图像。然后,构建加权L 1拟合能量项,量化原始图像与混合模糊拟合图像之间的差异,有效地处理灰度不均匀问题。最后,结合L^(2)拟合能量项,保证能量泛函的凸性,使得模型解的存在性和唯一性得以保证,避免陷入局部极小。另外,采用交替迭代算法对FAWFE模型进行数值求解,并与经典的活动轮廓模型对比。结果表明,FAWFE模型不仅可以准确定位目标边界,而且可以在0.6 s左右实现对图像的处理,对于合成图像和真实图像均有良好的处理效果。展开更多
The mixing process in a stirred tank of 0.476 m diameter with single, dual and triple 3-narrow blade hydrofoil CBY impellers was numerically simulated by using computational fluid dynamics (CFD) package FLU-ENT6.1. Th...The mixing process in a stirred tank of 0.476 m diameter with single, dual and triple 3-narrow blade hydrofoil CBY impellers was numerically simulated by using computational fluid dynamics (CFD) package FLU-ENT6.1. The multi-reference frame (MRF) and standard k-ε turbulent model were used in the simulation. The shaft power and the mixing time predicted by CFD were in good agreement with the experiment. The effects of tracer feeding and detecting positions on mixing time were investigated. The results are of importance to the optimum design of industrial stirred tank/reactors.展开更多
Based on the transport phenomena theory, the passive mixing of water and ethanol in different threedimensional microchannels is simulated numerically. The average variance of water volume fraction is used to index the...Based on the transport phenomena theory, the passive mixing of water and ethanol in different threedimensional microchannels is simulated numerically. The average variance of water volume fraction is used to index the mixing efficiency in the cases with different Reynolds number and different fabricated mixers. The results show that the efficiency of liquid mixing is progressively dependent on the convective transport as the Reynolds number increases. The efficiency of serpentine microchannel decreases with the increasing Reynolds number in the laminar regime. Altering the aspect ratio of channel inlet section has no significant effect on the mixing efficiency. Increasing the area of channel inlet section will cause the decrease of the mixing efficiency. The mixing in serpentine channels is the most efficient among three different mixers because of the existence of second flow introduced by its special structure.展开更多
Four empirical models are tested for fitting the T-y-x equilibrium data of ethanol-water mixture by minimizing the Root Mean Square （RMS） between equilibrium data and theoretical points. The total pressure of the co...Four empirical models are tested for fitting the T-y-x equilibrium data of ethanol-water mixture by minimizing the Root Mean Square （RMS） between equilibrium data and theoretical points. The total pressure of the correspondent data is 101.3 kPa. All models parameters are also identified. The study suggests that NRTL model fits the equilibrium data best with RMS = 0.4 %.展开更多
文摘为了对灰度不均匀图像进行分割,结合图像的局部和全局信息,提出基于加权L^(1)-L^(2)拟合能量项的模糊活动轮廓图像分割(fuzzy active contour based on weighted L^(1)-L^(2) fitting energy for image segmentation,FAWFE)模型。首先,利用模糊隶属度函数,基于图像局部和全局信息构建混合模糊拟合图像。然后,构建加权L 1拟合能量项,量化原始图像与混合模糊拟合图像之间的差异,有效地处理灰度不均匀问题。最后,结合L^(2)拟合能量项,保证能量泛函的凸性,使得模型解的存在性和唯一性得以保证,避免陷入局部极小。另外,采用交替迭代算法对FAWFE模型进行数值求解,并与经典的活动轮廓模型对比。结果表明,FAWFE模型不仅可以准确定位目标边界,而且可以在0.6 s左右实现对图像的处理,对于合成图像和真实图像均有良好的处理效果。
文摘The mixing process in a stirred tank of 0.476 m diameter with single, dual and triple 3-narrow blade hydrofoil CBY impellers was numerically simulated by using computational fluid dynamics (CFD) package FLU-ENT6.1. The multi-reference frame (MRF) and standard k-ε turbulent model were used in the simulation. The shaft power and the mixing time predicted by CFD were in good agreement with the experiment. The effects of tracer feeding and detecting positions on mixing time were investigated. The results are of importance to the optimum design of industrial stirred tank/reactors.
基金Supported by the National Natural Science Foundation of China (No. 20299030).
文摘Based on the transport phenomena theory, the passive mixing of water and ethanol in different threedimensional microchannels is simulated numerically. The average variance of water volume fraction is used to index the mixing efficiency in the cases with different Reynolds number and different fabricated mixers. The results show that the efficiency of liquid mixing is progressively dependent on the convective transport as the Reynolds number increases. The efficiency of serpentine microchannel decreases with the increasing Reynolds number in the laminar regime. Altering the aspect ratio of channel inlet section has no significant effect on the mixing efficiency. Increasing the area of channel inlet section will cause the decrease of the mixing efficiency. The mixing in serpentine channels is the most efficient among three different mixers because of the existence of second flow introduced by its special structure.
文摘Four empirical models are tested for fitting the T-y-x equilibrium data of ethanol-water mixture by minimizing the Root Mean Square （RMS） between equilibrium data and theoretical points. The total pressure of the correspondent data is 101.3 kPa. All models parameters are also identified. The study suggests that NRTL model fits the equilibrium data best with RMS = 0.4 %.
