This study proposes the use of generative adversarial networks (GANs) to solve two crucial problems in the unmanned ship navigation: insufficient training data for neural networks and convergence of optimal actions under discrete conditions. To achieve smart collision avoidance of unmanned ships in various sea environments, first, this study proposes a collision avoidance decision model based on a deep reinforcement learning method. Then, it utilizes GANs to generate enough realistic image training sets to train the decision model. According to generative network learning, the conditional probability distribution of ship maneuvers is learnt (action units). Subsequently, the decision system can select a reasonable action to avoid the obstacles due to the discrete responses of the generated model to different actions and achieve the effect of intelligent collision avoidance. The experimental results showed that the generated target ship image set can be used as the training set of decision neural networks. Further, a theoretical reference to optimize the optimal convergence of discrete actions is provided.
The aim of this study is to construct an unmanned ship swarms monitoring model to improve autonomous decision-making efficiency and safety performance of unmanned ship navigation. A framework is proposed to determine the relationship between on-board decision-making and shore side monitoring, the process of ship data detection, tracking, analysis and loss, and the application of decision-making algorithm, to discuss the different risk responses of specific unmanned ship types under various latent hazard environments, particularly in terms of precise conversion timing in switching over to remote control and full manual monitoring, to ensure safe navigation when the capability of automatic risk response inadequate. This frame-work makes it easier to train data and the adjustment for machine learning based on Bayesian risk prediction. It can be concluded that the automation level can be increased and the workload of shore-based seafarers can be reduced easily.
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Three-dimensional NiO nanorods were synthesized as anode material by electrospinning method. X-ray diffraction results revealed that the product sintered at 400 °C had impure metallic nickel phase which, however, became pure NiO phase as the sintering temperature rose. Nevertheless, the nanorods sintered at 400, 500 and 600 °C had similar diameters (∼200 nm).The NiO nanorod material sintered at 500 °C was chip-shaped with a diameter of 200 nm and it exhibited a porous 3D structure. The nanorod sintered at 500 °C had the optimal electrochemical performance. Its discharge specific capacity was 1127 mAh·g−1 initially and remained as high as 400 mAh·g−1 at a current density of 55 mA·g−1 after 50 cycles.
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