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Global offshore wind power is rapidly developing and has a broad market. China has the advantage of developing offshore wind power, which is the direction of future development of China's power generation industry. Because of the high maintenance and repair costs as well as the large sizes of wind power structures, damage to them could cause loss of lives and property. In this paper, a health monitoring method for analyzing offshore wind power structures based on a genetic algorithm and an uncertain analytic hierarchy process (AHP) is proposed. The uncertain analytic hierarchy process (AHP) is used to establish the hierarchical model. After calculating the weight range of each part, the optimal weight is obtained through the training and optimization of genetic algorithm, and the comprehensive weight table is obtained. Finally, the grading of health condition of the whole structure can be obtained by inputting the health indicators of each part based on the statistical distribution for weighted calculation. Based on the qualitative analysis of the uncertain analytic hierarchy process and the quantitative analysis of the genetic algorithm, the method is shown to reliably monitor the health of offshore wind power structures, reduce maintenance costs, and ensure staff safety. Both simulation and actual measurement experiments are performed in this study. The simulation based on the vibration data proves that the proposed structural health monitoring method for offshore wind power structures can evaluate the grading of health condition rapidly and accurately, using data in real time. Through the training and verification of simulation data, the accuracy of prediction after training can exceed 98%. Through a verification experiment using actual measured data, the vibration data measured by the offshore wind power structure during the healthy service period are evaluated. The evaluation results are found to be consistent with the actual operation state of the wind power structure. The proposed method can be used for quick, real-time evaluations.

Aiming at the demand for precise positioning of underwater device in marine controllable source electromagnetic (CSEM) exploration system, an underwater acoustic positioning method with one shipborne interrogator and two GPS buoys is proposed. Using numerical simulation method, the influence of ranging deviation and attitude angle deviation on the system positioning accuracy is studied. The simulation results show the effectiveness of the proposed method, which lays a theoretical basis for equipment development and test measurement.

In this study, a laser line auto-scanning system was designed to perform underwater close-range 3D reconstructions with high accuracy and resolution. The system changes the laser plane direction with a galvanometer to perform automatic scanning and obtain continuous laser strips for underwater 3D reconstruction. The system parameters were calibrated with the homography constraints between the target plane and image plane. A cost function was defined to optimize the galvanometer's rotating axis equation. Compensation was carried out for the refraction of the incident and emitted light at the interface. The accuracy and the spatial measurement capability of the system were tested and analyzed with standard balls under laboratory underwater conditions, and the 3D surface reconstruction for a sealing cover of an underwater instrument was proved to be satisfactory.

Due to the complexity and variability of the underwater acoustic channel, the communication signal is affected by multi-path, time delay, and Doppler frequency shift. Based on the advantageous characteristics of fractional Fourier transform on chirp signal processing, a fractional Fourier transform–based algorithm using combined linear frequency–modulated signal is proposed, which can estimate parameters of underwater acoustic channel and has a better performance than the existing methods. To distinguish multi-user in underwater acoustic communication system, a single-carrier direct sequence code division multiple access communication system combined with the fractional Fourier transform–based algorithm is proposed. Thus, a preliminary study on underwater multi-target identification is carried out. The simulation and experimental results show that the fractional Fourier transform–based algorithm is simple and effective, and the energy can be focused at the “best” fractional order, which can directly determine the multi-path number and complete the channel estimation. The proposed single-carrier direct sequence code division multiple access communication system has good performance on bit error rate when we use corresponding spreading code to distinguish multi-user.