Ship collision accidents not only endanger the safety of ships and personnel, but also may cause serious marine environmental pollution. To solve this problem, advanced technologies have been developed and applied in the field of intelligent ships in recent years. In this paper, a novel path planning algorithm is proposed based on particle swarm optimization (PSO) to construct a decision-making system for ship's autonomous collision avoidance using the process analysis which combines with the ship encounter situation and the decision-making method based on ship collision avoidance responsibility. This algorithm is designed to avoid both static and dynamic obstacles by judging the collision risk considering bad weather conditions by using BP neural network. When the two ships enter a certain distance, the optimal collision avoidance course and speed of the ship are obtained through the improved collision avoidance decision-making method. Finally, through MATLAB and Visual C++ platform simulations, the results show that the ship collision avoidance decision-making scheme can obtain reasonable optimal collision avoidance speed and course, which can ensure the safety of ship path planning and reduce energy consumption.

In order to solve the problem of improper thrust distribution of each thruster of underwater vehicle, the PSO optimization algorithm is used to solve the problem of thrust distribution. According to the spatial layout of the thruster, the algorithm model of the underwater vehicle propulsion system is established. The thrust input is carried out under the broken line search trajectory, and the simulation verifies the thrust allocation results of the PSO algorithm and the traditional pseudo-inverse method. The simulation results show that compared with the traditional algorithm. First of all, the PSO algorithm can set the physical threshold for each thruster to prevent the thruster from having too much thrust. Secondly, it can ensure that the thruster can turn with a reasonable torque to prevent the robot from drifting due to the large thrust gap. This paper provides a theoretical reference for thrust distribution of underwater salvage robot, and has practical engineering significance.

Liquefied gas carrier cargo handling operations are critical to ship safety. In order to improve the quality and efficiency of cargo handling of liquefied gas carriers, the loading and unloading operation of the liquefied gas carrier was studied and a set of LPG remote cargo operation simulator with automatic bargaining function was designed. Introducing the components of the simulator: the console unit and the simulated cargo tank unit in brief, the design ideas and specific functions of the automatic barge and remote control of the core part of the system are introduced in detail. The simulator feasibility verification is carried out by comparing the error between the actual loading and unloading operation with the system simulation loading and unloading operation. The simulation training functions verification is carried out by testing people who use the simulator for training. The final results show that the error is within the acceptable range, and people who use the simulator for training can pass an authoritative comprehensive exam. It is shown that that the system can simulate the important operations in the cargo handling process and has an excellent training effect.

The warm recycling technology has been increasingly used in many countries due to the environmental and financial benefits. In this study, the rheological and fatigue performance evolutions of warm-mix recycled asphalt materials during the secondary service period were evaluated in two scales, mixture and fine aggregate matrix (FAM). A laboratory simulation method was proposed to produce warm-mix recycled asphalt binders with various long-term aging levels for the mixture and FAM tests. The dynamic shear rheometer temperature and frequency sweep test and time sweep test were conducted to characterize the rheological and fatigue behavior of FAMs, respectively. The rheological and fatigue properties of asphalt mixtures were measured by the dynamic modulus test and semi-circular bending test, respectively. Effects of aging levels and recycling plans on different pavement performance were investigated. Performance correlations between the mixture and FAM were finally investigated by the statistical method. It is found that the secondary long-term aging causes the continuous increase in the stiffness and decrease in the viscoelasticity level in each material scale, indicating the improvement of the rutting resistance and the reduction of the fatigue resistance. The warm mix asphalt technology plays a positive role in the fatigue performance with a loss of the rutting resistance. Using the styrene butadiene rubber latex can improve different pavement performance within the whole time-temperature domain. Good performance correlations between the mixture and FAM are developed, indicating that the FAM may be the critical material scale for evaluating the rheological and fatigue performance of warm-mix recycled asphalt pavements.