The microbiologically influenced corrosion (MIC) is a serious issue that should be considered for effective risk-based integrity management of offshore systems under MIC. This paper presents a proper methodology by using a hybrid Bayesian network (BN) and Markov process to predict the MIC rate, failure probability, and critical failure year of an internally corroded subsea pipeline. The BN model is

This paper proposes a novel data-driven approach to estimate the navigable capacity of busy waterways, focusing on ships entering and leaving port, based on the structural characteristics of traffic flow driven by the Automatic Identification System (AIS) data. First, we collect the ship traffic flow in a busy waterway by processing the original AIS data and then identify the structural characteristics

Subsea pipelines with a free suspended span segment may be subject to upheaval buckling under high temperature, which may lead to a failure mode such as local buckling, fracture and fatigue. Mathematical models are established to study the upheaval buckling behaviour of subsea pipelines with a free span segment. Then, the accurate locations of the maxima of displacement and stress are obtained. The

A submerged floating tunnel (SFT) is a promising alternative to conventional bridges and tunnels, and can be potentially built in the Qiongzhou Strait in China. However, this area is under the threat of disasters including mega tsunamis and severe storm surges. To evaluate the hydrodynamic loads of the SFT in this hazardous zone subject to severe tsunami and typhoon impacts, the Delft3D-FLOW hydrodynamic

Oscillating water column (OWC) device is possibly the most studied among various wave energy converters and many different realizations of the technology have been investigated. To study the complex hydrodynamic behaviour of an OWC, a two-dimensional numerical wave tank based on the weakly compressible smoothed particle hydrodynamics (SPH) method is developed in this paper. A simplified pneumatic model

Tidal current energy is considered as one of the most important topics to be analyzed due to the penetration of renewable energy sources into the grid. The influence of unsteady wave is playing a crucial role on the tidal currents speed forecasting and its extracted power as well as its integration into the grid. The influence is not significant in case of single turbine or ducted tidal turbines. That

This paper solves the trajectory tracking problem for underactuated autonomous surface vessels in the presence of uncertainty dynamics and unavailable velocities. A robust controller is proposed by employing a neural network, command filtered backstepping method, and adaptive control method. Moreover, all tracking errors are guaranteed to be uniformly ultimately bounded on the basis of the Lyapunov

A general expression is formulated from the first principles for wave and current forces acting on a body. Morison's equation is recovered as a special case of the general formulation, thus establishing this heuristic-regarded equation on a firm theoretical ground. The drag force is clearly seen to be originating from the advective acceleration and the skin friction resistance, which is not explicitly

This paper investigates the position of the instantaneous center of rotation in pitch response of a moored vessel submitted to regular head waves. The vessel is assumed to respond only in surge, heave and pitch, which allows a 2D approach in the x-z plane due to symmetry. The concept is formalized via an analytical approach in a previous study, showing that even though this point is time dependent

The numerical results of local scour for bridge piers are significantly affected by the inlet turbulent boundary conditions. A novel self-sustaining model (SSM) and corresponding the new inlet turbulent boundary conditions are proposed to quickly obtain a stable flow field of horizontal homogeneity. The Reynolds averaged Navier-Stokes (RANS) equations, and standard k-ԑ turbulence model are employed

Free hanging is vulnerable to dynamic motion at the top end inducing axial compression at the touchdown point. Numerical approaches in consideration with multiple degrees of freedom and nonlinear drag force have been succeeded at evaluating dynamic characteristics of free-hanging slender structures accurately. On the other hand, analytical investigations into the mechanism determining dynamic tension

Global offshore wind power is rapidly developing and has a broad market. China has the advantage of developing offshore wind power, which is the direction of future development of China's power generation industry. Because of the high maintenance and repair costs as well as the large sizes of wind power structures, damage to them could cause loss of lives and property. In this paper, a health monitoring

Field observations over decades have found that the surface roughness of coral reefs is typically one or two order of magnitude larger than that of sandy beaches. To better reproduce the solitary wave transformation and run-up over fringing reefs with large bottom roughness, a numerical wave tank based on the CFD tool OpenFOAM® is developed in this study. The Reynolds-Averaged Navier-Stokes (RANS)

The hydrodynamic characteristics of a novel twin-protuberance hydrofoil design mimicking the two prominent tubercles present on a humpback whale flipper are investigated. The foil has NACA 634-021 section with a span/chord ratio of 2, having twin leading-edge protuberances- each of amplitude 10% of the chord length. A characteristic feature of this foil is its capability to restrict the separation

In the present study, regular water wave interaction with rubble mound offshore breakwaters (RMOB) is investigated. The porosity of the RMOB is uniform, and the breakwaters are placed on the uniform seabed. Three different types of breakwaters such as (i) RMOB with still water level at the crest, (ii) emerged RMOB, and (iii) submerged RMOB are considered for the present analysis. The associated boundary

An event-triggered controller (ETC) for global full-state stabilization of under-actuated surface vessels (USVs) is proposed. Based on an inner–outer loop structure with Lyapunov control design technique, the USV dynamics are separated into two subsystems to facilitate the design and stability analysis. A time-varying variable is constructed to design the desired velocities used as virtual control

The floating platform with taut or semi-taut mooring systems is the main option for oil and gas exploitations in deep sea. However, it has been reported that the reciprocating motion of the mooring line tends to induce the seabed trench near the anchor, which consequently reduces the anchor capacity. In this paper, two parts of work have been carried out to enhance the understanding of the seabed trench

Surf-riding phenomenon occurs when a ship sailing in following waves is accelerated to wave celerity. In this paper, surf-riding occurrence is studied for the parent hull of the Systematic Series D by 3 degrees of freedom (DOF) CFD simulations. Simulation cases are chosen following IMO recommendations for a wavelength to ship length range and following IMO criterion for ship speed cases. Initial conditions

This article presents a detailed numerical flow assessment of the boundary layer and wake of a full-scale cargo ship. The assessment was conducted using a sophisticated numerical approach that is able to resolve large turbulent scale vortices contained in the flow. The physical flow features of the boundary layer and wake investigated include mean-velocity, near-wall shear stress and vorticity fields

In this paper, high-speed impacting different size water-filled containers by projectiles have been performed experimentally, particular attention is given to characterizing the container confinement effects on the cavity characteristics induced by regular projectiles impacting into the confined containers. Experimental results indicate that the confinement effect on the cavity evolution is mainly

In this paper neural-network (NN) based adaptive trajectory tracking control scheme has been designed for underactuated Autonomous Underwater Vehicles (AUVs) which are subjected to unknown asymmetrical actuator saturation and unknown dynamics. First, some control preliminaries and assumptions along with AUV kinematic & kinetic models and trajectory tracking problems are elaborated. Secondly, the tracking

The light-weight gravity installed plate anchor (L-GIPLA) is a plate-shaped anchor for securing offshore floating structures, which is dynamically installed with the aid of a booster. Therefore, it is necessary to investigate the hydrodynamic characteristics of the hybrid anchor (L-GIPLA + booster) during free fall in water. Model tests are conducted in the present study to investigate the drag coefficient

Marine current turbines (MCTs) has progressively attracted wider interest from the industry and many research initiatives due to its potential as a novel world energy resource. However, several technological issues amongst others fault detection of MCT blades still require further progress for their successful implementation. Indeed, power generation is likely to progressively degrade due to blade

Bridge alarms are a plausible way to reduce the ship collision probability by timely alerting the officer on watch of a conflict. However, there currently are no dedicated methods for alerting a stand-on ship to compensate the unawareness of or inactive response of a give-way ship to dangerous encounter situations. Therefore, this article proposes a collision alert system from the stand-on ship perspective

Resistance reduction has always been a concerning problem in pipeline transportation projects. Moreover, adding fine particles has shown resistance reduction. Therefore, we studied the effect of adding finer particles on the transport characteristics of coarse-particle slurries in pipelines. The flow conditions and slurry characteristics, such as the flow velocity and particle volume concentration

The near-trapping effects on wave-induced dynamic seabed response and liquefaction close to a multi-cylinder foundation in storm wave conditions are examined. Momentary liquefaction near multi-cylinder structures is simulated using an integrated wave-structure-seabed interaction model. The proposed model is firstly validated for the case of interaction of wave and a four-cylinder structure, with a

Two-dimensional high-order spectral/hp computations are carried out for a cylinder undergoing a sinusoidal rotary oscillation about its own axis. Results are examined for Re=200 and a fixed oscillation amplitude of θ0=π. The study concentrates on a domain of forcing frequencies ranging from 0 to 5f0, with f0 being the natural shedding frequency of the fixed cylinder. The drag of the cylinder is measured

A Simulink code for numerical simulation of ship manoeuvring is developed based on the appropriate differential equations. Both the Abkowitz and MMG models are implemented as choices according to the available hydrodynamic particulars of a given ship. Reliability of the developed code is assessed by performing the turning and zigzag tests for two different ships, employing the Abkowitz and MMG models

An experimental and numerical study on the hydrodynamic characteristics of arc-shaped plate-type (ASPT) breakwaters was carried out. The accuracy and reliability of the developed 2D numerical model were verified through experimental results, which show the following. As the relative plate width increases, a decrease in Kt and a slight increase in Kr occur. The maximum increase in the transmission coefficient

Simulating the flow around a propeller using large-eddy simulation (LES) with the immersed boundary (IB) method is challenging and computationally expensive. In this work, we carry out the grid-dependence study of LES with IB for simulating a propeller in crashback mode using four sets of gradually refined grids. The simulation results show that the grid-resolution requirements for accurately predicting

The Weakly-Compressible Moving Particle Semi-implicit (WC-MPS) approach is applied to investigate the wave propagation and the flow fields induced by sliding blocks. Since there are already studies focusing on an inclination slope of 45°, two slope angles, 40° and 50°, are used to obtain the additional experimental results. Sliding blocks are released under water, where the top edges are parallel to

The modernization of cathodic protection system of the Baltic Beta platform legs is described. It was that the sacrificial anodes cone-shaped groups were to be placed on the seabed at a depth of 80 m. The measurements results of cathodic protection effectiveness during its ten-years operation are presented. The effectiveness was assessed based on the potential value along the entire length of the legs

In recent years, caisson foundations are being increasingly used as alternative foundations for supporting offshore renewable energy structures. In general, caisson foundations for offshore wind turbines (OWTs) are subjected to combined loadings including lateral, vertical and overturning moments. To guarantee the normal operation of OWTs and reduce uncertainty in the design of OWT foundations, the

In this paper, local scour around a subsea structure supported by a skirted mudmat foundation is explored experimentally. For simplicity the structure is represented as a submerged circular cylinder founded on a concentric circular mudmat. The experiments are conducted in the clear-water regime and various geometries are considered by varying the height of the submerged cylinder relative to its diameter

A novel three-dimensional model is proposed to study vortex-induced vibration (VIV) problems of top-tensioned risers. The model is based on the vector form intrinsic finite element (VFIFE) method and applicable to the fully-coupled cross-flow and in-line riser VIV scenarios. The axial time-varying dynamics and movement at the top end boundary of risers are also considered in the model. By using the

Manoeuvring in adverse weather conditions has significant challenges for the shipmaster especially when the ship is equipped with the smaller propulsion power. The automatic control methods for safe manoeuvring in severe weather conditions have not been studied extensively since manual control is applied in these conditions. Moreover, in most numerical simulations, PID control is used due to its simplicity

Laboratory experiments and numerical simulation were conducted to study the residual liquefaction mechanism of two-layer seabed with upper crust layer under standing waves. In this study, the buildup process of pore pressure and onset of liquefaction were firstly analyzed. Furthermore, the residual liquefaction mechanism at the nodal section was discussed. In addition, a parametric study was conducted

With a wide use of AIS data in maritime transportation, there is an increasing demand to develop algorithms to efficiently classify a ship’s AIS data into different movements (static, normal navigation and manoeuvring). To achieve this, several studies have been proposed to use labelled features but with the drawback of not being able to effectively extract the details of ship movement information

Thrust allocation is a key procedure in the dynamic position system (DPS) of marine vessels. The present work aims to study the characteristics of dynamic optimization in thrust allocation. A two-phase analysis process is proposed. In phase-I, the model for thrust allocation is generated from the viewpoint of multiobjective optimization. Fuel consumption and tear-and-wear on the thrusters are chosen

This study proposes a new length scale that measures the size of the wave-induced vortex street on one side of a pipeline. By conducting dimensional analysis, we show that the equilibrium scour depth under a pipeline, when normalized by the vortex street size, is generally dependent on the densimetric Froude number. However, by analyzing the published data, the dependence is found to be insignificant

In order to probe the mechanism of human causation factors in ship navigation accidents effectively, the Reason-SHEL model was introduced to establish human causation factors index system meanwhile the multidimensional association rule algorithm was applied to obtain the chains of human causation factors. Firstly, the human factors index system is constructed based on the Reason-SHEL model. Secondly

Vertical cylinders are widely used as supporting structures in ocean engineering applications. Shock waves due to underwater explosives (UNDEX) can cause serious damage to offshore structures, which has attracted the interest of many researchers. The propagation characteristics of shock waves produced by UNDEX across a cylinder are a complex physical phenomenon that involves fluid-structure dynamic

Fluid-structure interactions (FSI) of multiple cylindrical structures frequently occur in crossflows. Due to the different wake interference regions of flexible cylinders with different diameters, the interaction between multiple cylinders is complicated and sensitive to the centre-to-centre spacing ratio and diameter ratio. Limited information has been presented on the flow-induced vibration (FIV)

Path following control plays an essential role in improving accuracy of navigation and achieving a smooth motion control. However, the performance will exhibit large lateral errors caused by weak maneuverability, large time-lag, and large ocean current disturbance when the wave glider is gliding with a low and time-varying speed. An adaptive path following control integrated an adaptive line-of-sight

When the VIVACE converter is operated in shallow water, the free surface in its proximity plays a critical role in affecting the dynamic response and the consequent energy harvesting performance of the converter. In this study, a series of experimental tests are conducted for the flow-induced vibration of a single-cylinder VIVACE converter in the TrSL3 regime with the Reynolds number 34,931

A semi-analytic dynamic model is developed for vibro-acoustic analysis of submerged coupled propeller-shaft-hull systems under propeller forces. The propeller, shaft and hull are idealized as a lumped mass, multi-span beam and ring-stiffened shell of revolution, respectively. Stern, middle and thrust bearings are simulated as spring-damping systems. The hull is firstly decomposed into many segments

In this paper, a finite-time extended state observer-based nonsingular fast terminal sliding mode control (NFTSMC) is proposed for the trajectory tracking of autonomous underwater vehicles (AUVs) with various hydrodynamic uncertainties and external disturbances. First, a proportional–integral velocity variable based third-order fast finite-time extended state observer is designed to estimate the lumped

Maintenance improvement is affected by many uncertain factors such as maintainer experience, machine deterioration state, maintenance tools and equipment, it is very hard to determine each restoration degree ahead of repair operation. Therefore, this paper considers a maintenance problem in the presence of competing risks (degradation and sudden failure) under stochastic maintenance quality for a ship

In this paper, Finite Element-Indirect Boundary Element (FE-IBE) coupling approach based on the Isogeometric Analysis (IGA) framework is proposed to deal with Acoustic-Structural Interaction (ASI) problems. Numerical simulation of thin-walled structures is carried out by using isogeometric Reissner-Mindlin shell theory. The isogeometric indirect boundary element method (IBEM) is used to simulate the

With the implementation of an energy efficiency design index, energy-saving devices (ESDs) have received increasing research interest. In this study, experimental and numerical analyses were performed on a 25-m long ore carrier model to investigate the working mechanism of ESDs comprising a pre-swirl stator and a rudder bulb. The interactions between the hull, propeller, rudder, and ESDs were observed

The hybrid monopile foundation is an alternative for offshore wind turbines. The parametric study has been performed through a series of centrifuge tests for the optimal design of the hybrid foundation. The wheel diameter, wheel thickness, and pile length are considered in the analysis. The lateral capacity of the hybrid monopile foundation increases with the wheel diameter and tends to accelerate;

In this study, the effective wake factors of a self-propelled container ship were investigated by Telfer's GEOSIM method based on CFD (Computational Fluid Dynamics). For this purpose, the self-propulsion characteristics of KCS (KRISO Container Ship) at three different model scales and full-scale were determined at Fr = 0.26 by unsteady RANS (Reynolds Averaged Navier-Stokes) solver. All scales corresponded

Porous structures have been widely applied in the coastal and ocean engineering. In the CFD (Computational Fluid Dynamics) simulations of interactions between waves and porous structures, the microscopic model establishment approach usually requires huge amounts of fine grids around the model boundary, thus causing a huge computational overhead. This paper establishes a CFD numerical model using a

A new unified particle model that couples the Smoothed Particle Hydrodynamics (SPH) and a discontinuous approach known as the Volume Compensated Particle Method (VCPM) is developed to solve Fluid Structure Interaction (FSI) problems involving large deformation. Unlike the model that couples the Smoothed Particle Hydrodynamics and the Discrete Element Method (i.e. SPH-DEM) in which the applicable Poisson's

Pipeline walking is a global axial movement caused by the asymmetric distribution of axial force along the pipeline during the repetitive operational loading cycle. The pipeline walking rate, increasing with the loading cycles, may lead to high stress thereby the failure of connectors at PLETs or PLEMs. Current research studies and design guidelines focused on free-end pipelines and neglected changes

With the continuous development of nuclear power application, the structural design and verification of pressure-resistant cabin has become the key technology for nuclear-powered ships or nuclear-powered icebreakers. Through the design of reinforced pressure-resistant structure, the ultimate strength of the pressure-resistant cabin was investigated by experimental analysis and nonlinear finite element

In this study, we devised a new WEC (wave energy converter) called SR-WEC (Surface Riding WEC). The SR-WEC consists of two bodies: the outer cylinder with an armature assembly (body #1) and a magnet assembly (body #2) sliding inside the armature. For the SR-WEC, the relative sliding displacement and velocity are caused by gravity acceleration and the outer cylinder's motions, and they lead to electrical