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Automatic generation algorithm of orthogonal grid based on recurrent neural network
HUANG Zhongzhan, XU Shiming
Journal of Computer Applications    2020, 40 (7): 2009-2015.   DOI: 10.11772/j.issn.1001-9081.2019112062
Abstract373)      PDF (1651KB)(294)       Save
With the rapid development of computer graphics, industrial design, natural science and other fields, the demand for high-quality scientific computing methods is increased. These scientific computing methods are inseparable from high-quality grid generation algorithms. For the commonly used orthogonal grid generation algorithms, whether they can reduce the computational amount and whether the manual intervention can be reduced are still the main challenges faced by them. Aiming at these challenges, for the single-connected target region, an automatic generation algorithm of orthogonal grid was proposed based on Long Short-Term Memory network (LSTM), one of the recurrent neural networks and Schwarz-Christoffel conformal mapping (SC mapping). Firstly, the basic conditions of the Gridgen-c tool based on SC mapping were used to transform the grid generation problem into an integer programming problem with linear constraints. Next, a classifier, which is capable of calculating the probability of the corner type of each vertex of the target polygonal region, was obtained by using the pre-processed GADM dataset and LSTM training. This classifier was able to greatly reduce the time complexity of integer programming problem, making the problem be solved quickly and automatically. Finally, the simple graphics areas, animated graphics areas and geographical boundary areas were taken as examples to conduct a grid generation experiment. Results show that for simple graphic areas, the proposed algorithm can reach the optimal solution on all examples. For animated graphic areas and geographical boundary areas with complex boundaries, the example grid results show that the proposed algorithm can make the calculation amount in these target areas reduced by 88.42% and 91.16% respectively, and can automatically generate better orthogonal grid.
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Bi-direction pedestrian flow by the spread of the influence of emergencies
LIANG Mingfu, FANG Shaomei, HUANG Zhongzhan, CAI Qinyi
Journal of Computer Applications    2017, 37 (5): 1496-1502.   DOI: 10.11772/j.issn.1001-9081.2017.05.1496
Abstract480)      PDF (1142KB)(507)       Save
When the emergencies happen, the pedestrian walking behavior would change by the emergencies and their influence. The research on the pedestrian walking characteristics in emergencies could optimize the evacuation efficiency. Aiming at the shortcomings of the data acquisition in the existing research, the real pedestrian scene video was processed and the relevant data were extracted, and the general walking characteristics of the pedestrian without emergencies were analyzed. Aiming at the pedestrian flow in emergencies, the spread of the emergency influence and the pedestrian self-organization phenomena in emergencies were described by k-nearest neighbor algorithm and the resultant force, a novel Cellular Automata (CA) model whose cellulars were suffered from the influence of normal walking, emergencies and security marks was proposed. The simulation of bi-direction pedestrian evacuation in emergencies was carried out by the proposed model. The experimental results show that, when the separation distance of security marks in a narrow pedestrian passage mark is 0, 10, 20 cellular, the distance of the safety mark distribution has not obvious effect on pedestrian evacuation. Through the study of whether there is influence among the population, the effect of evacuation is mainly affected by the spread of emergencies by nearby pedestrians. That the impact of emergencies is too large or too small will cause congestion and is not conducive to the evacuation of the crowd. The simulation results are consistent with the scenario of pedestrian evacuation in reality.
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