To improve the noise reduction accuracy of reciprocating friction vibration signals of piston ring friction pairs in marine diesel engines, this paper proposes a collaborative noise reduction method that integrates complementary ensemble empirical mode decomposition (CEEMD) and an adaptive correlation coefficient screening mechanism. Simulated vibration signals were obtained using the BRUKER UMT friction and wear testing machine to construct an experimental dataset. The original signals were subjected to multi-scale decomposition using CEEMD, and effective intrinsic modal components were screened using an adaptive correlation coefficient threshold. The dominant noise component was removed to achieve signal reconstruction. MATLAB software was applied to implement the noise reduction processing. Three types of indicators—signal-to-noise ratio (SNR), normalized cross-correlation coefficient (NCC), and mean square error (MSE)—were used for quantitative evaluation. Multi-scale permutation entropy (MPE) theory was also innovatively introduced to verify the dynamic characteristics of the denoised signal. The experimental results show that the CEEMD adaptive correlation coefficient screening method has significantly improved noise reduction performance compared to other methods. The correlation coefficients between the multi-scale permutation entropy image of the stripped noise signal and the overall laboratory noise signal image are all above 0.8, thus proving the accuracy of effective signal denoising.

In 2025, the global new shipbuilding market maintained its recent positive momentum, characterized by full orderbooks and sustained high prices, successfully concluding the 14th Five-Year Plan period (2021-2025). China's shipbuilding industry continued to lead global growth, with all major indicators reaching historic highs and further consolidating its position as the world leader. Looking ahead to 2026, operating at a market peak demands heightened caution. Potential risks such as geopolitical competition, demand adjustments, and financial volatility require vigilant attention. Crucially, it is essential to analyze whether the underlying supportive factors will fade, shift, or strengthen—especially regarding the sustainability of shipping demand, the scale of vessel scrapping, and the absorption of new tonnage capacity. These issues represent the core uncertainties and primary sources of divergence in market trend judgments. This paper reviews the development of the global new shipbuilding market in 2025, analyzes the key variables that will influence the market in 2026, forecasts future trends, and provides insights to the industry for its stable development.

The analysis object of this paper is a cylindrical pressure shell with a single orthogonally nozzle and reinforcement structures, consisting of a nozzle wall and an insert plate. Taking the non-iteration design process of the reinforcement structures of this cylindrical pressure shell as an example, this paper proposes a non-iteration design method based on the gradient boosting decision tree (GBDT). This work provides a reference for the design of structures without the need of iteration design process. The non-iteration design method proposed in this paper includes three parts: dataset generation, generation of the non-iteration design surrogate model, and development of a dedicated APP for non-iteration design. Firstly, a machine learning dataset is obtained by the parametric finite element analysis through ABAQUS-Python for the reinforcement structures of the cylindrical pressure shell. Then, based on the Gradient Boosting Decision Tree and the multi-output regressor, a non-iteration design surrogate model is generated based on the dataset. Finally, a dedicated forward design APP (HUST-FWD01) is developed to standardize the non-iteration design and verification processes for the reinforcement structures. The results show that the dimensions of the reinforcement structure can be obtained without the need of iteration by the non-iteration design surrogate model, which is generated based on the non-iteration design framework proposed in this paper. In the surrogate model, the maximum stress near the opening of the pressure shell is used as the input, and the dimensions of the reinforcement structures are the outputs. The verification examples show that the errors are all within 3% between model inputs and the FEA results corresponding to model outputs. The research results can provide a design method without the need of iteration for the reinforcement structures of cylindrical pressure shell with a single orthogonally hole as well as the structures akin to them.

A software has been developed to predict the inherent longitudinal vibration characteristics of the ship shafting. The software is developed using the QT platform, with the core solver written in MATLAB and the solution algorithm using the Holtz method. The results are compared and verified with the simulation results of ANSYS and the longitudinal vibration calculation results of an actual shafting system. On this basis, the developed software is used to discuss the variation of the longitudinal vibration characteristics of the shafting under different shafting properties. The results show that the properties affecting the inherent longitudinal vibration characteristics of the shafting mainly include the crank radius, crank thickness, longitudinal stiffness of thrust bearings and material elastic modulus. The relevant research results can provide references for the vibration and noise reduction of the ship shafting.

A software for rapid estimation of the natural frequency of the stern frame vibration has been developed in order to quickly estimate the important parameter of the natural frequency of the stern frame vibration. This software uses QT and MATLAB for interface design and core solver compilation based on the empirical formula for the calculation of the natural frequency of stern frame vibration given in the “Method for Structural Design and Strength Calculation of Naval Surface Ships”. The influence of different hull parameters on the vibration of the stern frame is summarized based on the developed software system. It is found that the factors affecting the natural frequency of the single-arm stern frame are mainly the length of the shaft frame arm and the average inertia moment of the shaft frame section, and the factors affecting the natural frequency of the double-arm stern frame are the length of the shaft frame arm, the cross-sectional area of the shaft frame arm, and the angle between the shaft centerline and the plane of the shaft frame. The results can provide references for the selection of parameters during the design of the stern frame. The practical value of this software is demonstrated in the rapid estimation of the natural frequency of the stern frame vibration.

Owing to the complex geometric curved surface of the propeller, general software for the rapid prediction of the vibration characteristics of the propeller with trailing edge cutting is developed for the geometric modelling and vibration analysis of the trailing edge cutting. The development of the software for the vibration analysis of the propeller with trailing edge cutting is completed by using the finite element method together with the MATLAB programming language and the ANSYS module based on the QT platform. This software is used to calculate and analyze the first five-order natural frequency values of the 4384 propeller. It is found that the relative errors are within 5% combined with the published data in order to prove the accuracy of the software program and the calculation results. The software is characterized of easy usage, fast calculation and great engineering application value. It provides a new analysis method for the matching of ship-machine-propeller after the trailing edge cutting.