A semi-sealed cylindrical shell is a hollow cylinder in which one end open and the other sealed. In order to systematically study cavity evolution, hydrodynamic characteristics, corresponding structural response of during high-speed vertical water entry, numerical simulation carried out based on Star-CCM+ ABAQUS collaborative method. The results show that nested formed presents three different morphologies as penetrates water. Moreover, jet under shell, profoundly influences characteristics....

It is a complicated problem to study high-speed water entry of projectile passing through an ice hole in polar environment. This involves the constraint on free surface and low-temperature cavitation during entry. In this paper, numerical method involving modified thermodynamic model introduced process. The validated by comparing results cavity evolution with experimental data. dynamics overwater at high speed different ambient temperatures are studied. evolution, flow field, motion state...

This article investigates the leader-follower formation control problem for multiple underactuated autonomous underwater vehicles with model uncertainties and external disturbances. Sliding mode control, multilayer neural network, adaptive robust techniques are employed to design a controller vehicles. After that, Lyapunov-based stability analysis is proposed guarantee that all variables uniformly ultimately bounded in closed-loop system. The following advantages of this approach...

Nowadays, the utilization of memristors to enhance dynamical properties chaotic systems has become a popular research topic. In this paper, we present design novel 2D memristor-enhanced polynomial hyper-chaotic map (2D-MPHM) by utilizing cross-coupling two TiO2 memristors. The 2D-MPHM were investigated using Lyapunov exponents, bifurcation diagrams, and trajectory diagrams. Additionally, Kolmogorov entropy sample also employed evaluate complexity 2D-MPHM. Numerical analysis demonstrated...

In marine applications, estimating velocity fields or other states from limited data are important as it provides a reference for active control. this work, we propose PVNet (Pressure-Velocity Network), an improved U-shaped neural network (UNet) combined with Transformer Modules and Multi-scale Fusion Modules, to predict pressure on the hydrofoil surface. To improve prediction accuracy, position encodings have been incorporated into input features. Tests cavitation dataset of NACA66...

At low Froude numbers, vertical and oblique impacts of deformable spheres into water are performed. The dependence levels the hydrodynamics, cavity formations, stress responses on angle investigated. Based theoretical numerical analyses, differences between in sphere deformations formations clarified. Elastic forces inside induce different models deformation behaviors during entry, with a smaller extends formation time oblate nested cavity. Over single period, hydrodynamic do not...

In the face of mounting economic constraints, researchers are increasingly turning to data-driven methods for reconstructing unknown global fields from limited data. While traditional compressed sensing (CS) technology addresses this challenge, least absolute shrinkage and selection operator algorithm within CS encounters difficulties in precisely solving basis coefficients. This challenge is exacerbated by frequently observation matrix, often necessitating optimization resolution. study...

This paper investigates the problem of path following control underactuated autonomous underwater vehicles in presence model uncertainties and external disturbances. With three-dimensional error established based on virtual guidance method, a robust system is proposed using command filtered backstepping control, neural networks, adaptive techniques. Then, Lyapunov-based stability analysis demonstrates that all signals are bounded errors ultimately converge to neighborhood origin. Following...

Despite cavity dynamics have been studied for more than a century, formations during water entry of deformable spheres rarely studied. Series interesting cavities arise vertical spheres. We study these phenomena experimentally and numerically. Experimental observations show that can produce three typical cavities: dumpy cavity, tight nested cavity. Numerical modeling accounts the effect elasticity on dynamics. Our results motion parameters used to characterize walls present hierarchical...

This study investigated the mechanical behavior of fabricated corrugated steel plate during tunnel construction period and influence on surrounding ground settlement, aiming to provide insight into support structure design construction. To this end, a reality engineering case (e.g., Beijing Metro Line 27) numerical simulation were used analyze characteristics supporting evaluate safety prefabricated structure. The results showed that maximum subsidence is located 11 m away from shaft,...

The study of the water entry projectile passing through ice hole can solve special issue under marine environmental constraints. We conducted experiments to validate effect constraint on dynamics cavity and then used numerical simulations investigate holes with different sizes rotation degrees. results show that affects evolution motion state projectile. splash crown flows back contacts surface when small-sized hole. Cavity collapses before pinch-off. at as size increases, morphology is...