In this research, two distinct designs of protective structures were developed to address structural damage caused by ships impacting the internal structures of floating docks during maintenance operations. The designed protective structures consist of support sections and load-bearing sections, with the load-bearing section comprising three frame sections. For ease of description, the front frame section, middle frame section, and rear frame section are referred to as Frame A, Frame B, and Frame C, respectively. A drop-weight test was conducted with a stern-shaped indenter impacting the structures at 3.89 m/s. This study also assessed varying impact speeds and positions. The results showed that Specimen 2 had localized indentations on Frame B, while Specimen 1 exhibited overall deformation of Frame B and additional deformations in Frame A. The simulations agreed with the experimental results, confirming the model’s accuracy. At speeds from 2.34 m/s to 5.45 m/s, Specimen 2 consistently showed localized deformations, while Specimen 1 showed comprehensive deformation of Frame B at 3.89 m/s due to lower rigidity. When the indenter impacted the specimens at different locations with a speed of 5.45 m/s, the two specimens exhibited varying degrees of damage. As the impact location shifted from the central area to the end, the maximum indentation depth of Specimen 1 decreased from 52.26 mm to 41.71 mm, while that of Specimen 2 decreased from 43.26 mm to 38.50 mm. The reduction in indentation depth and extent as the impact location approached the support frame can be attributed to the increasing involvement of the web plate beneath the frame in resisting the impact. Additionally, compared to Specimen 1, Specimen 2 exhibited a relatively smaller overall indentation depth, and the impact of location variation on indentation depth was also relatively minor.

The number of hologram points in near-field acoustical holography (NAH) for a vibro-acoustic system plays a vital role in conditioning the transfer function between the source and measuring points. The requirement for many overdetermined hologram points for extended sources to obtain high accuracy poses a problem for the practical applications of NAH. Furthermore, overdetermination does not generally ensure enhanced accuracy, stability, and convergence, owing to the problem of rank deficiency. To achieve satisfactory reconstruction accuracy with underdetermined hologram data, the best practice for choosing hologram points and regularization methods is determined by comparing cross-linked sets of data-sorting and regularization methods. Three typical data selection and treatment methods are compared: iterative discarding of the most dependent data, monitoring singular value changes during the data reduction process, and zero padding in the patch holography technique. To test the regularization method for inverse conditioning, which is used together with the data selection method, the Tikhonov method, Bayesian regularization, and the data compression method are compared. The inverse equivalent source method is chosen as the holography method, and a numerical test is conducted with a point-excited thin plate. The simulation results show that selecting hologram points using the effective independence method, combined with regularization via compressed sensing, significantly reduces the reconstruction error and enhances the modal assurance criterion value. The experimental results also support the proposed best practice for inverting underdetermined hologram data by integrating the NAH data selection and regularization techniques.

Aiming to solve the problem of collisions that may occur with ships during the operation of the floating dock, which may lead to functional failure or even destruction of the dock, a new collision avoidance device has been researched and designed. Through simulation analysis, the structural response of different collision speeds, different contact areas, and different structural forms of collision avoidance structures under typical working conditions was studied, and the basic law of buffering performance of in-dock collision avoidance devices for floating docks was derived, on the basis of which a new type of in-dock collision avoidance device for floating docks was designed. This study is important to ensure the operational safety and functionality of the floating dock. It can also provide a useful reference for the design of other ship collision avoidance structures.

The rapid and automatic solution of ship stowage scheme is of great practical significance for the efficient delivery of marine equipment. Based on the characteristics of ro-ro loading of emergency rescue vehicles, the ship stowage problem of multi-layer and multi-type rescue vehicles under different emergency tasks is abstracted as a multi-objective optimization model. The algorithm of ship stowage is designed based on particle swarm optimization, and the optimization of stowage is divided into two stages. In the first stage of ship stowage, adaptive mutation and local search idea represented by Tabu search are integrated into PSO algorithm and the above algorithm is discretized; in the second stage, the adaptive mutation and heuristic rules are integrated into the PSO o optimize the allocation of vehicle parking positions. As the determination of stowage scheme needs to be dynamically changed according to the changes of the disaster situation, different rescue tasks will correspond to different target weights. The effectiveness and feasibility of the multi-objective ship stowage algorithm are verified by a case study.

A scientific and effective ship stowage scheme is of great practical significance for the realization of efficient maritime force projection. Ship stowage scheme is a multi - criteria decision making problem, by analyzing the basic requirements and difficulties of ship stowage, the evaluation indicators of ship stowage plan are clarified, and the index system for the evaluation of the ship stowage scheme is established. Use fuzzy analytic hierarchy process (FAHP) to calculate the weight of each evaluation index of ship stowage scheme, on the basis of simplifying the analysis of multiple sub-objectives of the stowage scheme, a mathematical model of ship stowage is established. The AHP-fuzzy-Topsis evaluation model is established by combining with the technique for order preference by similarity to an ideal solution. And ten stowage schemes are taken as examples to conduct case analysis. The results show that the effectiveness and feasibility of the evaluation system of ship stowage schemes, and lays a theoretical foundation for the evaluation system of ship stowage schemes.

The efficiency of vertical loading of equipment at sea is constrained by the compensating ability for wave motion, with the accuracy of wave compensation influenced by various factors such as wave simulation, prediction, and the response of vessels to wave loads. Enhancing the accuracy of wave compensation and optimizing the efficiency of vertical loading operations are current challenges. Based on the analysis of the entire process of missile vertical loading, this study constructed a missile vertical loading system model with a core comprising a wave compensation system and vertical loading equipment. Furthermore, considering the effects of random ocean waves and vessel responses to wave loads, this paper developed a ship motion simulation platform based on mathematical models of random waves and wave energy spectrum simulation technology. Through this platform, simulated curves of wave energy spectrum, transverse and longitudinal ship roll amplitudes, wave tilt angles, and transverse and longitudinal ship motion angles were obtained. Finally, using wave simulation data, the effectiveness of the AR prediction model was validated, and simulation verification and error analysis of short-term ship motion prediction based on time series AR autoregressive models were conducted, comparing the accuracy and applicability of different prediction methods.