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Welding ball edge bubble segmentation for ball grid array based on full convolutional network and K-means clustering
ZHAO Ruixiang, HOU Honghua, ZHANG Pengcheng, LIU Yi, TIAN Zhu, GUI Zhiguo
Journal of Computer Applications    2019, 39 (9): 2580-2585.   DOI: 10.11772/j.issn.1001-9081.2019030523
Abstract395)      PDF (1006KB)(352)       Save

For inaccurate segmentation results caused by the existence of edge bubbles in welding balls and the grayscale approximation of background due to the diversity of image interference factors in Ball Grid Array (BGA) bubble detection, a welding ball bubble segmentation method based on Fully Convolutional Network (FCN) and K-means clustering was proposed. Firstly, a FCN network was constructed based on the BGA label dataset, and trained to obtain an appropriate network model, and then the rough segmentation result of the image were obtained by predicting and processing the BGA image to be detected. Secondly, the welding ball region mapping was extracted, the bubble region identification was improved by homomorphic filtering method, and then the image was subdivided by K-means clustering segmentation to obtain the final segmentation result. Finally, the welding balls and bubble region in the original image were labeled and identified. Comparing the proposed algorithm with the traditional BGA bubble segmentation algorithm, the experimental results show that the proposed algorithm can segment the edge bubbles of complex BGA welding balls accurately, and the image segmentation results highly match the true contour with higher accuracy.

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Hybrid parallel genetic algorithm based on Sunway many-core processors
ZHAO Ruixiang, ZHENG Kai, LIU Yao, WANG Su, LIU Yan, SHENG Huanxue, ZHOU Qianhao
Journal of Computer Applications    2017, 37 (9): 2518-2523.   DOI: 10.11772/j.issn.1001-9081.2017.09.2518
Abstract631)      PDF (891KB)(473)       Save
When the traditional genetic algorithm is used to solve the computation-intensive task, the execution time of the fitness function increases rapidly, and the convergence rate of the algorithm is very low when the population size or generation increases. A "coarse-grained combined with master-slave" HyBrid Parallel Genetic Algorithm (HBPGA) was designed and implemented on Sunway "TaihuLight" supercomputer which is ranked first in the latest TOP500 list. Two-level parallel architecture was used and two different programming models, MPI and Athread were combined. Compared with the traditional genetic algorithm implemented on single-core or multi-core cluster with single-level parallel architecture, the algorithm using two-level parallel architecture was implemented on the Sunway many-core processors, better performance and higher speedup ratio were achieved. In the experiment, when using 16×64 CPEs (Computing Processing Elements), the maximum speedup can reach 544, and the CPE speedup ratio is more than 31.
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