In digital holographic microscopy, when the object is placed near the COD, the Fresnel approximation is no longer valid and the convolution approach has to be applied. With this approach,the sampling spacing of the re...In digital holographic microscopy, when the object is placed near the COD, the Fresnel approximation is no longer valid and the convolution approach has to be applied. With this approach,the sampling spacing of the reconstructed image plane is equal to the pixel size of the COD. If the lateral resolution of the reconstructed image is higher than that of the COD,Nyquist sampling criterion is violated and aliasing errors will be introduced. In this Letter,a new method is proposed to solve this problem by investigating convolution reconstruction of digital holograms. By appending enough zeros to the angular spectrum between the two FFT＇s in convolution reconstruction of digital holograms,the displayed resolution of the reconstructed image can be improved. Experimental results show a good agreement with theoretical analysis.展开更多
In the long distance transportation of slurry filled for mining filling,there exist complex variation rules of pressure and flow velocity,pipe distribution location and other influencing factors.Electrical capacitance...In the long distance transportation of slurry filled for mining filling,there exist complex variation rules of pressure and flow velocity,pipe distribution location and other influencing factors.Electrical capacitance tomography(ECT)is a technique for visualizing two-phase flow in a pipe or closed container.In this paper,a visual detection method was proposed by image reconstruction of core,laminar,bubble and annular flow based on ECT technology,which reflects distribution of slurry in deep filling pipeline and measures the degree of blockage.There is an error between the measured and the real two-phase flow distribution due to two factors,which are immature image reconstruction algorithm of ECT and difference of flow patterns leading to degrees of error.In this paper,convolutional neural networks(CNN)is used to recognize flow patterns,and then the optimal image is calculated by the improved particle swarm optimization(PSO)algorithm with weights using simulated annealing strategy,and the fitness function is improved based on the results of the shallow neural network.Finally,the reconstructed binary image is further processed to obtain the position,size and direction of the blocked pipe.The realization of this method provides technical support for pipeline detection technology.展开更多
文摘In digital holographic microscopy, when the object is placed near the COD, the Fresnel approximation is no longer valid and the convolution approach has to be applied. With this approach,the sampling spacing of the reconstructed image plane is equal to the pixel size of the COD. If the lateral resolution of the reconstructed image is higher than that of the COD,Nyquist sampling criterion is violated and aliasing errors will be introduced. In this Letter,a new method is proposed to solve this problem by investigating convolution reconstruction of digital holograms. By appending enough zeros to the angular spectrum between the two FFT＇s in convolution reconstruction of digital holograms,the displayed resolution of the reconstructed image can be improved. Experimental results show a good agreement with theoretical analysis.
基金Project(51704229)supported by the National Natural Science Foundation of ChinaProject(2018YQ2-01)supported by the Outstanding Youth Science Fund of Xi’an University of Science and Technology,China。
文摘In the long distance transportation of slurry filled for mining filling,there exist complex variation rules of pressure and flow velocity,pipe distribution location and other influencing factors.Electrical capacitance tomography(ECT)is a technique for visualizing two-phase flow in a pipe or closed container.In this paper,a visual detection method was proposed by image reconstruction of core,laminar,bubble and annular flow based on ECT technology,which reflects distribution of slurry in deep filling pipeline and measures the degree of blockage.There is an error between the measured and the real two-phase flow distribution due to two factors,which are immature image reconstruction algorithm of ECT and difference of flow patterns leading to degrees of error.In this paper,convolutional neural networks(CNN)is used to recognize flow patterns,and then the optimal image is calculated by the improved particle swarm optimization(PSO)algorithm with weights using simulated annealing strategy,and the fitness function is improved based on the results of the shallow neural network.Finally,the reconstructed binary image is further processed to obtain the position,size and direction of the blocked pipe.The realization of this method provides technical support for pipeline detection technology.
