The blade is the key component for energy capture in horizontal axis tidal current turbine, and the blade’s design is directly related to the efficiency of the power generation device. The seawater flow velocity is a crucial parameter for blade design. Since the seawater velocity changes constantly, it is extremely important to determine the design velocity of the blade. This article proposes a calculation method for the design velocity of the blade so that the designed blade can achieve better energy collection efficiency under a variable flow velocity. This study performed the following investigations: (1) The author tested and analyzed the seawater velocity variation at the experimental site, determining the designed flow velocity via calculations; (2) The author combined the blade element momentum and Wilson’s optimization design method using the MATLAB software to calculate the blade shape parameters and predict the performance under a number of different flow velocity forecasts; (3) When testing the device under sea conditions, the experimental results showed that the performance capture devices and digital projections are basically the same, which verifies the validity and effectiveness of the design method.

Industrial robotic arms are often subject to significant end-effector pose deviations from the target position due to the combined effects of nonlinear deformations such as link flexibility, joint compliance, and end-effector load. To address this issue, a study was conducted on the analysis and compensation of end-position errors in a six-degree-of-freedom robotic arm. The kinematic model of the robotic arm was established using the Denavit–Hartenberg (DH) parameter method, and a rigid–flexible coupled virtual prototype model was developed using ANSYS and ADAMS. Kinematic simulations were performed on the virtual prototype to analyze the variation in end-effector position errors under rigid–flexible coupling conditions. To achieve error compensation, an approach based on an Enhanced Crayfish Optimization Algorithm (ECOA) optimizing a BP neural network was proposed to compensate for position errors. An experimental platform was constructed for error measurement and validation. The experimental results demonstrated that the positioning accuracy after compensation improves by 75.77%, fully validating the effectiveness and reliability of the proposed method for compensating flexible errors.

In this study, a new type of double-pontoon floating breakwater was designed to improve the wave attenuation performance through the addition of suspended Savonius propeller-blade. Its hydrodynamic characteristics were studied through numerical simulations and performance-testing experiment. The following investigations were performed in this study: Firstly, wave theory and hydrodynamic theory were combined to calculate the wave attenuation performance and motion response of double-pontoon floating breakwater under linear wave conditions. The numerical results showed that the wave attenuation performance was better under a specific wave period and height, the transmission coefficient reached a relatively small value, and the mooring line tension responded periodically and satisfied the condition of maximum breaking force. Secondly, three key geometric parameters of breakwater were researched, including the relative spacing of pontoons, the relative spacing between pontoons and blades, and the height–diameter ratio of Savonius blades. The calculation results showed that the pontoon spacing was closer to the wavelength and the breakwater wave attenuation performance was better. Lastly, experimental tests were also performed on the new double-pontoon floating breakwater and the results showed that the wave attenuation performance and numerical projections were basically the same, which verified the validity and effectiveness of the design method.

The dynamic characteristics of high-precision planetary reducers in terms of vibration response and dynamic transmission error have a significant impact on positioning accuracy and service life. However, the dynamics of high-precision two-stage helical planetary reducers have not been studied extensively enough and must be studied in depth. In this paper, the dynamic characteristics of the high-precision two-stage helical planetary reducer are investigated in combination with simulation tests, and the microscopic modification of the gears is optimized by the helix modification with drums, with the objective of reducing the vibration response and dynamic transmission error. Considering the time-varying meshing stiffness of gears and transmission errors, a translation–torsion coupled dynamics model of a two-stage helical planetary gear drive is established based on the Lagrange equations by using the centralized parameter method for analyzing the dynamic characteristics of the reducer. The differential equations of the system were derived by analyzing the relative displacement relationship between the components. On this basis, a finite element model of a certain type of high-precision reducer was established, and factors such as rotate speed and load were investigated through simulation and experimental comparison to quantify or characterize their effects on the dynamic behavior and transmission accuracy. Based on the combined modification method of helix modification with drum shape, the optimized design of this type of reducer is carried out, and the dynamic characteristics of the reducer before and after modification are compared and analyzed. The results show that the adopted modification optimization method is effective in reducing the vibration amplitude and transmission error amplitude of the reducer. The peak-to-peak value of transmission error of the reducer is reduced by 19.87%; the peak value of vibration acceleration is reduced by 14.29%; and the RMS value is reduced by 21.05% under the input speed of 500 r/min and the load of 50 N·m. The research results can provide a theoretical basis for the study of dynamic characteristics, fault diagnosis, optimization of meshing parameters, and structural optimization of planetary reducers.

Aiming at the breeding environment where the construction of marine pastures requires low wind and waves, a floating breakwater (FB) with a Savonius type (referred to as S type) runner with wave absorption and energy reduction function is studied for wave absorption and energy reduction in aquaculture sea areas. The wave-absorbing and energy-reducing performance of the floating breakwater is studied by the method of combining numerical simulation and experiment. Using Star-CCM+ numerical simulation software, based on linear wave theory and energy conservation law, using overlapping grid technology, calling DFBI model, second-order time discretization, a three-dimensional flow field model of the floating breakwater was established and numerically simulated. At the same time, a floating breakwater physical test system was developed for experimental verification, the transmission wave and the conversion power consumption of the S-shaped runner under different wave heights and different periods were measured, and the results Please carefully check the accuracy of names and affiliations. of numerical simulation and physical experiments were comprehensively evaluated. The research results show that the floating breakwater based on the S-shaped runner has the functions of reducing the wave height and reducing the wave energy, which have guiding significance for practical engineering.

Due to the limitations of farming space, fish cage aquaculture is gradually expanding into offshore deep-sea areas, where the environmental conditions surrounding deep-sea fish cages are more complex and harsher compared to those in shallower offshore locations. Conventional multi-point moored gravity flexible fish cages are prone to damage in the more hostile environments of the deep sea. In this paper, we present a design for a single-point mooring vessel-shaped fish cage that can quickly adjust its bow direction when subjected to waves from various angles. This design ensures that the floating frame consistently responds effectively to wave impacts, thereby reducing the wave forces experienced. The dynamic response of the floating frame and the mooring forces were simulated by coupling the Smoothed Particle Hydrodynamics method with the Moordyn numerical model for mooring analysis. The three degrees of freedom (heave, surge, and pitch) and the mooring forces of a scaled-down vessel-type ship cage model under wave conditions were investigated both numerically and experimentally. The results indicate that the error between the simulation data and the experimental results is maintained within 6%. Building on this foundation, the motion response and mooring force of a full-sized ship-shaped net box under wave conditions off the southeast coast of China were simulated. This study examined the effects of varying mooring lengths and buoy configurations on the motion response and mooring force of the fish cage. Finally, we constructed the fish cage and tested it under the influence of a typhoon. The results demonstrate that the fish cage could operate stably without structural damage, such as mooring failure or floating frame breakage, despite the significant deformation of the floating frame.