Showing papers in "Applied Ocean Research in 2021"

TL;DR: In this paper, a review of particle methods in hydrodynamics-related problems in ocean and coastal engineering is presented, where the problems are placed into three categories according to their physical characteristics, namely, wave hydrodynamic and corresponding mass transport, wave-structure interaction, and wave-current-sediment interaction.

TL;DR: A path planning strategy unified with a collision avoidance function based on deep reinforcement learning (DRL) is proposed, and it is shown that the enhanced DRL can effectively realize autonomous collision avoidance path planning.

TL;DR: A concise review on latest advances related to development of entirely Lagrangian meshfree computational methods for hydroelastic fluid-structure interactions (FSI) in ocean engineering and highlights several corresponding key issues.

TL;DR: Experimental results illustrate that the proposed algorithm could improve the navigation accuracy and the robustness of resisting unknown measurement uncertainty compared to the conventional method.

TL;DR: In this article, the improved smoothed particle hydrodynamics (SPH) method with numerical diffusive terms, referred to as δ-SPH, has been widely applied into the studies of engineering problems, especially in the fields of ocean and coastal engineering.

TL;DR: An improved Otsu algorithm is proposed to accurately identify obstacles and Kalman filtering is also introduced to estimate dynamic obstacles in the complex operation environment of the pipeline inspection.

TL;DR: The results show that the algorithms are credible in two and multi ships encounter situations, even the targets ships take unexpected course alteration and the own ship could well avoid collision with shorelines, reefs and moving ships or obstacles under external disturbance.

TL;DR: This research provides new hydraulic soft actuators with simple drive and control for underwater robotic system and will promote the development and offer a new idea for underwater soft actuator.

TL;DR: In this paper, a theoretical method for the precise descent of an arbitrary-geometry plunger is derived and constraints on the produced wave height are given, taking wedge-shaped, box-shaped and cylinder-shaped plungers as examples.

TL;DR: A structural dynamics model is incorporated to account for the motions and deformations of the net and the fluid-structure interaction of floating objects with mooring lines, nets and fluid is accounted for in the model.

TL;DR: Comparisons of fault detection rate and false alarm rate of other state-of-the-art methods on simulated and measured datasets demonstrated the excellent performance of the proposed hybrid fault monitoring scheme.

TL;DR: The study found that of the 34 factors related to the safety of navigation, E10/violation of COLREG Rule-5 (look-out), E9/improper use of ECDIS, and E8/impropering use of radar significantly effect groundings, indicating that maintaining a safe navigation watch is crucial to prevent future accidents.

TL;DR: A robust neural network, hyperbolic tangent function, and dynamic surface control technique are simultaneously utilized to propose the prescribed performance-based controller which is robust against completely unknown parameters, nonlinear hydrodynamic damping, actuators saturation nonlinearity, NN approximation errors and time-varying environmental disturbances.

TL;DR: In this paper, a partitioned MPS-FEM coupled method is employed for two-dimensional and three-dimensional free surface flow interacting with deformable structures, and the results obtained show good agreement with published experimental result as well as referenced numerical results.

TL;DR: A feasibility study of hydraulic fracturing and horizontal well applied to the hydrate reservoir in China's first offshore hydrate production site to increase gas production from hydrates was done as mentioned in this paper, where a numerical model was built by Tough+Hydrate to study the influences of horizontal well location and horizontal fracture length on gas production.

TL;DR: An approach-angle-based three-dimensional path-following control scheme has been proposed for underactuated Autonomous Underwater Vehicle (AUV) which experiences unknown actuator saturation and environmental disturbance.

TL;DR: A shape optimization method of Petrel-L based on the approximate model technology, the establishment of which is introduced in detail, is proposed and results indicate that the increase rate of gliding range can reach 7.64% when the hotel load is 0.5 W and the pitching angle is ±12°.

TL;DR: A scenario-based stochastic linear integer programming model is developed that can reduce the total costs in conjunction with providing reasonable speed and route optimization decisions in the shipping industry.

TL;DR: In this article, the coupling strategy of an improved particle hydrodynamics (SPH) method and smoothed finite element method (SFEM) is integrated with advanced fluid modeling techniques, and is extended and validated for modeling liquid sloshing with rigid or deformable structures.

TL;DR: In this paper, a new combined concept consisting of an oscillating water column (OWC) device and an offshore wind turbine for the multi-purpose utilization of offshore renewable energy resources is presented.

TL;DR: The event-triggered tracking control of fully actuated autonomous underwater vehicles (AUVs) in the vertical plane is investigated, and the closed-loop stability is analyzed based on the observer-based tracking errors, and all of them are proved to be semi-globally uniformly ultimately bounded (SGUUB).

TL;DR: This paper proposes a distributed deep reinforcement learning algorithm for USV formations that can learn two critical abilities, i.e. adaptability and extendibility that enable formations to arbitrarily increase the number of USVs or change formation shapes.

TL;DR: The proposed end-to-end image segmentation method for side-scan sonar mounted on Autonomous Underwater Vehicle can achieve better segmentation results than UNet, SegNet and their derivative networks and has better generalization ability.

TL;DR: In this paper, a method is proposed for weakening the tip-clearance flow in pump-jet propulsors by increasing section thickness and rake of rotor blades from 95% tip-radius to the tip.

TL;DR: The stability analysis via the Lyapunov method indicates that the uniformly ultimate boundedness of all signals of the AUV trajectory tracking close-loop control system is found.

TL;DR: Numerical results show that the low-frequency components in the reconstructed displacements can be more easily identified than those in the accelerations, which implies that the developed displacement-based OMA strategy is more suited to offshore structures with low- frequencies.

TL;DR: In this paper, a finite element (FE) modeling of stick-slip vibrations of the full drill string was proposed based on a rate-dependent formulation of bit-rock interaction, in which the cutting process was integrated through the frictional contact.

TL;DR: Based on linear potential flow theory, a semi-analytical model was developed using the matching eigenfunction method for a dual pontoon system in the presence of partially reflective seawall as discussed by the authors.

TL;DR: In this paper, a S175 hull model is adopted for seakeeping analysis in both uni-and bi-directional regular waves and it is shown that ship motion response is generally larger than that in uni -directional waves.

TL;DR: In this paper, a non-integration displacement reconstruction method is proposed to estimate the displacement of offshore structures from accelerometers, where the displacement is derived from the estimated complex exponential parameters of measured acceleration signal with a form of fraction.