Global route planning is a pivotal function of unmanned surface vehicles (USVs). For ships, the safety of navigation is the priority. This paper presents the VK-RRT* algorithm as a way of designing the planned route automatically. Different from other algorithms or studies, this study employs electronic navigation chart (ENC) vector data instead of grid maps as the basis of the search, which reduces data error when converting the vector map into the grid map. In addition, Delaunay triangulation is employed to organize vector data, in which the depth value is taken as a factor to ensure the safety of the planning route. Furthermore, the initial planned route is not suitable for ship tracking as it does not consider the ship motion characteristics. Therefore, the planned route needs to be further optimized. In the final part, we also conducted experiments to verify the effectiveness and advantages of the proposed algorithm. The results show that the proposed algorithm could reduce the lengths of paths by about 23% on average and save planning time; these are largely dependent on the environment.
1 January 2021 in Nuclear Technology and Radiation Protection
When verifying the authenticity for nuclear warheads dismantlement toward a treaty partner's obligation, nuclear arms verification technologies are critical since only nuclear disarmament treaties are not sufficient to neutralize the existential threat of nuclear weapons. In this work, we present a verification method combining a numerical observer model and physical encryption techniques. The performance of the method is quantified by Monte Carlo simulations with several typical deception scenarios. Simulation results show this method can efficiently complete identification tasks in the presence of noise (<5 %) and source-term variability, meanwhile exhibiting high security against brute-force attacks which reconstruct detection data by the exhaustive method.