The fire resistance of internally ring-stiffened multi-planar tubular TT-joints was studied and formulated in the present paper. TT-joints were examined under axial loading. After developing a finite element (FE) model and its verification against the experimental data, a total of 324 numerical analyses were performed on 81 FE models of internally ring-stiffened multi-planar TT-joints at four different

Being an impressive representative of gravity installed anchors (GIAs), the OMNI-Max anchor has many attractive attributes and becomes more and more a conspicuous role in recent deepwater applications. However, the pullout capacity property of OMNI-Max anchors has not been well understood due to their three-dimensional structure and the loading way in variational seabed conditions. Full knowledge of

When an internal solitary wave (ISW) breaks over a sloping bottom in the ocean, turbulent mixing causes energy dissipation that is associated with the breaking type. In a two-layer fluid, when pycnocline thickness is negligible, the breaking can be categorized into one of four breaker types: surging, plunging, collapsing, and fission breakers. The latest classification into four breaker types is based

It is common practice to represent wave climate and sea severity through significant wave height. The development of accurate probabilistic models of wave height is paramount in ocean-related activities (e.g., offshore structures, weather routing, wave energy assessment studies). In this work, several models for the probabilistic description of the significant wave height are examined and evaluated

Ship motion prediction is applied to the shipboard stabilized platform to keep the equipment on the platform stable all the time, which is of great practical significance to the safety and efficiency of shipboard equipment operation. Long Short-term Memory (LSTM) Network is a classic time series prediction method that has made remarkable achievements in this field. However, the dynamic frequency range

In traditional pigging operations, sealed disks having a specific amount of interference guarantee that the pig runs at the velocity of the gas behind it. A bypass flow path in the pig lowers its speed while causes the uneven pig motion, which is referred to as slippage. The slippage raises the risk of the pig becoming stuck and negatively impacts the pipe and related facilities. This paper proposes

The dynamic response of the telescopic gangway strongly links to the relative motion which is significant when the gangway vessel works along with another floating unit in proximity. The failure might cause operational downtime or even personnel casualty. In this paper, gangway motions, including extension, retraction, rotations, and relative motions, are studied numerically in the time domain and

This paper is concerned with a multi-underactuated AUV three-dimensional (3-D) formation control method with a multi-time-scale structure in the presence of uncertain nonlinearities and environmental disturbances. First, a double-layer independent position-velocity fixed topology is adopted to overcome the drawback of narrow bandwidth of underwater communication. Then, an extended high-gain observer

The Golden Horn (Estuary) is a hotspot for marine pollution because of its close proximity to the Strait of Istanbul (Strait) with dense maritime traffic and high pollution risk of oil spill. Transport and fate of water and contaminants in Strait and Estuary are analyzed by three-dimensional numerical models. Eddies forming at the Golden Horn junction (Junction), either on a single layer or distributed

An analytical solution for evaluating the critical pressure of pipes under hydrostatic pressure was proposed. The stability equations and the correct boundary conditions for 3D problem in cylindrical coordinates were established by using energy method. The stability equations were solved together with the derived correct boundary conditions and the solution of the critical pressure for elastic buckling

In this study, a floating barge moon pool platform model equipped with an NREL 5 MW wind turbine and mooring systems was numerically and experimentally tested under wave and wind loads to analyze the hydrodynamic performance and stability of the barge platform and the mooring system in a 50 m water depth condition. The numerical model was based on ANSYS AQWA, and this hydrodynamic model included nonlinear

This paper proposes a study on the hull structure optimization of a semi-submersible medical platform. The hull structure sizes have great important effect on the cost, hydrodynamics, global, and manufacture of the whole semi-submersible platform. In this paper, the economy, lightweight and higher stability should be ensured for the medical platform during the optimization design process. The hull

Free-surface oscillations within a square harbor subjected to solitary waves are investigated through physical experiments. The effects of various wave heights and water depths on the resonance within the harbor are examined. In this study, the technique of wavelet-based bicoherence spectra is employed for the first time to investigate the nonlinear wave–wave interaction of the transient harbor resonance

A parallel multidisciplinary optimization design is proposed for the lines design of an underwater vehicle. Resistance and energy consumption are concerned about in obtaining the optimized lines. Collaborative optimization strategy is adopted to construct the optimization framework. The simulated annealing algorithm in combination of the modified method of feasible directions are taken as the optimization

In this paper, an elastoplastic modeling method is presented for dynamic consolidation of liquefiable seabed around a pipeline subjected to ocean environmental loadings (i.e. wave and current). Special attention is given to the cyclic plasticity modeling of liquefiable marine sediments and the evolving soil-pipeline interactions, in association with the Biot's dynamic consolidation theory. Motivated

Multi-peaked directional wave spectra have been estimated by the well-known maximum likelihood method and modeled by applying a numerical optimization approach that uses a gradient OQNLP algorithm. The research is based on field measurement data from a 210-km-long area at the northern coasts of the Gulf of Oman. This modeling approach allows the fitting of various spectral models. Accordingly, three

This paper provides a systematic state of the art review on tracking the fine scale movements of fish with the use of autonomous maritime robotics. Knowledge of migration patterns and the localization of specific species of fish at a given time is vital to many aspects of conservation. This paper reviews these technologies and provides insight into what systems are being used and why. The review results

Violent pulsating bubbles behave diversely in different circumstances. It is a multi-scale problem in both space and time. In 3-D problems, the numerical simulation is usually too expensive to implement in practice with a fixed grid. In this paper, a 3-D multi-fluid model is established based on the Eulerian finite element method and the adaptive mesh refinement technique to investigate the bubble

This analytical study presents the solitary wave interaction with a bottom-mounted surface-piercing V-shaped breakwater. The breakwater is impermeable, thin, and rigidly fixed on the bottom. As a key element, an imaginary closed cylinder with an arm’s length radius was introduced so that the fluid domain was divided into three subdomains by an imaginary interface, within which the solutions were described

Although being a common situation for fish and underwater vehicles, limited research has been reported for a fish-like body swimming in oblique incoming flows. The present work employs the immersed boundary-lattice Boltzmann method to numerically study the dynamics of this problem. A more comprehensive analysis method, which utilizes the effective force parameters that consolidate the angle of attack

The studies on floating offshore wind turbines have been increasing over recent decades due to the growing investments of industries in marine renewable energy. Compared with horizontal-axis wind turbines, research on vertical-axis wind turbines is relatively few, though the latter may have advantages over the former in some aspects, for example, potentially lower cost of energy. In this paper, the

An Eulerian vorticity method, based on a vorticity-stream function formulation, initially developed for the 2-D viscous unsteady flow past a circular cylinder, is extended in the case of 2-D flow past a rotating cylinder in a rotational frame of reference. The vorticity equation is shown to have the same form as in the case of an inertial frame of reference. Thus, the general structure of the numerical

Three dimensional Rankine source model is utilized to investigate the hydrodynamic responses for wave radiation problems under arbitrary seabed condition in time domain. The free surface, seabed surface and body surface are presented by layer of continuous panels rather than a discretization by isolated points. These panels are positioned exactly on the fluid boundary surfaces and no desingularization

Currently, most autonomous underwater gliders (AUGs) operate on primary lithium batteries. As the state of charge of a primary lithium battery and the influence of marine environment on the glider are difficult to measure, it is hard to forecast the energy consumption of a glider accurately, which has caused the failure of many glider missions. For the purpose of safely deploying the AUG mission and

In this paper, full-scale data for two ships have been used for the comparison of five different added resistance methods. The effect of using separate wave spectra for wind waves and swell on performance prediction has been explored. The importance of the peak enhancement factor(γ) in the JONSWAP spectrum for added resistance computation has been studied. Simulation model including calm water resistance

Theoretical solutions including the Morison equation have been widely used to estimate the wave forces exerted on offshore structures of vertical cylindrical configuration. However, none of those methods can accurately predict the wave force of the secondary load cycle induced by a steep wave acting on the cylinder. In this study, regular waves of different wave steepness are generated using an experimental

The hydrodynamic interaction between ships or between the ship and the bank was studied by numerical methods. A number of new numerical results were obtained, for both ship–ship interaction and ship–bank interaction cases, by applying the double-body potential flow code HYDINTER earlier developed at Instituto Superior Técnico (University of Lisbon, Portugal). A comparative numerical study was made

The wider use of electronic devices in shipping has led to the introduction of new navigation control systems and decision support tools for collision avoidance. The application of these systems improves the data utilisation and allows for the prediction of ship's performance in various operational conditions. In this study, a decision support methodology for collision avoidance of ocean going vessels

For an improved estimation of marine structural reliability, a consideration of random variable dependency is essential. With a limited study on dependence modelling of marine structures, this study proposes a framework for reliability assessment of ocean structural systems with multidimensional variables. This framework captures possible nonlinearity and tail dependence in the variables using vine

Rotating stall in centrifugal pumps takes place frequently under part-load conditions, along with high pressure pulsation. The major focus for studies is rotating stall inside the impeller, rarely paying attention to that in the vaned diffuser. In this study, rotating stall behavior in a vaned diffuser centrifugal pump has been numerically investigated, and the cross-power spectrum method is adopted

In this paper, feasibility of applying moving baffles linked to a spring system as a mitigation device to suppress liquid sloshing of a container undergoing a harmonic and seismic excitation is investigated numerically using the Coupled Eulerian-Lagrangian (CEL) technique. The interaction between the Eulerian fluid domain where the material can pass through the mesh and the Lagrangian tank domain where

This paper presents a novel adaptive neural event-triggered formation control strategy for underactuated surface vehicles (USVs) in the presence of marine practical constraints, i.e. the waypoints-based planned path and actuator failures. The proposed strategy is composed of the guidance model and the control one. For the guidance part, the logic virtual ship (LVS) guidance principle is developed to

The objective of this work is to experimentally investigate the dynamic evolution of flow structure and pressure distribution on the water entry of a bulbous bow. We focus on the water entry of an arbitrary bow based on the 18.5 station line of the KRISO container ship with a typical bulbous bow. Time-resolved particle image velocimetry (TR-PIV) is utilized to capture the transient flow information

Dams are an important part of a country's infrastructure. After the dam breaks, the collision force of the water column, if severe enough, would incur a great deal of destruction and damage and needs to be concerned specially. In this work, 3D dam-break flows against various forms of the obstacle are numerically simulated by the smoothed particle hydrodynamics (SPH) method. In order to tackle boundaries

In this paper, a saturated trajectory tracking controller is proposed for high-speed surface vessels whose actuator dynamics is not negligible in practice. The hyperbolic tangent function is used as a stabilizer term to design a tracking controller via the dynamic surface control approach to improve the controller performance for all subsystems in the presence of input saturation, unmodeled dynamics

A novel magnetic bistable device (MBD) is proposed to improve the efficiency of energy harvesting of a point absorber wave energy converter (WEC) by decreasing the potential barrier of the bistable energy absorber. The novel MBD is mainly composed of two pairs of coaxial permanent magnet rings with different sizes. For the permanent magnet rings, one pair has the same magnetic field direction to provide

We present a smooth particle hydrodynamics (SPH) formulation that captures the sloshing frequencies of tanks and accurately simulates long-duration violent sloshing in partially filled tanks of arbitrary shape. The SPH simulations are performed using a modified version of the open-source code DualSPHysics that incorporates a density-based stabilization (δ-SPH) and imposes wall boundary conditions via

Recently (Adcock and Taylor, 2009) devised a method to estimate the underlying directional spreading from a single point measurement. Subsequently, this method has been successfully applied to sea states with frequency independent directional spreading. In contrast, the present work has applied this method to synthetic sea states generated with an underlying frequency dependent spreading. However,

Large floating structures such as platforms, breakwaters and piers, have been constructed in many countries in coastal areas in a bid to increase land space. Due to construction ease and operational flexibility, these facilities are commonly consisted of relatively small floating units that are subsequently connected on sea. This paper first describes box-like structural systems for concrete floating

Restricted waters present several challenges for ship builders and operators. The proximity of the seabed and river or canal banks cause viscous effects to be more pronounced than in unrestricted waters. These effects do not follow a linear scaling law, which is typically assumed in terms of sinkage and trim. Moreover, the resistance of the ship is increased in a complex fashion, which has largely

High installation and maintenance costs of electrical submersible pumps (ESP) operating in deepwater production wells led to the development of rigorous tests to verify the performance and structural integrity of this equipment. The so-called integration tests are the last opportunity to evaluate the ESP set before it is dispatched for installation in oil production wells. Due to the possibility of

The wave characteristics in the nearshore waters of Sanmen Bay are presented based on the AWAC-measured data from October 2016 to September 2017 at the wave observation station with 7.5m water depth. The wave parameters and the wave spectral variations are statistically analyzed, and the wave height distribution, the wave period distribution, and the joint distribution of wave height and period are

Excellent seakeeping performance is the basis of safe ship operation. An anti-rolling device employing swinging rotating cylinders based on the Magnus effect can provide anti-rolling measures at any ship speed. In this study, the operating principle of a Magnus anti-rolling device was examined by studying its hydrodynamic performance using large eddy simulation method. A dimensionless parameter—the

The paper presents simulation results of an inland container vessel designed to be operated in the inland waters of China. Initially, calm water simulations are performed in open water with varying draft and speed to determine the possible propulsion power required by the vessel for regular operations. Next, static drift simulations are performed with a heave and pitch-free motion at varying drift

The growing attention in reducing the risk of collisions or groundings during the approach to a harbour or while navigating in narrow fairways, makes the escort activities of paramount importance for a safe navigation in different scenarios. To this end, since early-design stage, Classification Societies prescribe to evaluate the maximum steering and braking force the tug is capable to provide. The

Frequent water traffic accidents pose severe threats to human life and property safety, the water environment, and adverse effects on social stability. Understanding historical accidents is essential for accident prevention and risk mitigation. However, at present, research on the comprehensive statistical analysis of characteristics and causes of ship accidents that occurred in the inland water areas

Collison between ships is one of the major contributors to maritime accidents. To reduce ship collision accidents, the research on collision avoidance decision-making has been drawing much attention from various parties. In this research, extensive literature and expert knowledge are collected and analyzed to identify the common sense and discrepancies between collision avoidance decision-making for

Extreme waves usually emerge from intensive wave groups. Detection of wave groups from random waves may be a key step in predicting the occurrence of extreme events. A new method to discriminate wave groups in random waves based on the wavelet transform is proposed and investigated. The approach can identify wave groups effectively and efficiently. To test the methods, propagation of random wave trains

In case of a four-screw ship, the propellers show different hydrodynamics performance due to the asymmetric distribution of the wake. And the particularity of the scale effect on wake field for this type of ship would make a more complicated characteristics on propeller bearing force. In this paper, a numerical simulation study of scale effect on propeller unsteady bearing force of a four-screw ship

Wave breaking is one of the most violent phenomena in air-water interface interactions that need to be considered in ship and offshore structures design. Spilling breaking waves induced by a shallowly submerged hydrofoil are investigated using a Navier-Stokes solver for two-phase flow. Computed wave profiles and velocity fields are compared with experimental results and good agreement obtained. A related

Motivated by soial and environmental reasons, water scarcity has become a global top agenda item. Egypt is one of the countries suffering from an acute shortage of freshwater. A promising novel and efficient solution to overcome Egypt's freshwater shortage, especially in remote coastal areas far from the national grid of freshwater and electricity, is a mobile floating desalination plant (FDP) powered

A numerical model containing density stratified layers of liquid oil and water in a rectangular tank is modeled to interact with a rigid porous structure in the form of a T-shaped baffle under sloshing conditions. The arbitrary Lagrangian-Eulerian method is used to track the evolution of the interfacial and free surface wave, with the Navier Stokes and Brinkman's equations governing the incompressible

In the present study, the stress concentration factors (SCFs) in circular hollow section X-connections retrofitted with fiber reinforced polymer (FRP) under compressive load are evaluated. After validation of the FE model with several available experimental data, a set of 279 FE models was created to parametrically investigates the efficacy of the FRP and connection geometry on the SCFs and SCF ratios

In multi-body offshore systems, a telescopic gangway is often adopted for personnel transfer, the feasibility and safety of which are crucial. The coupled dynamics and gangway responses of a turret-moored floating production storage and offloading (FPSO) unit and a semi-submersible accommodation platform (AP) were investigated numerically in this study. Both side-by-side arrangement and the configuration

This paper employs numerical simulation to study the hydrodynamics of porpoising behavior in dolphins. The virtual swimmer is a three-dimensional dolphin-like body with prescribed kinematics. A four-stage model of this behavior is proposed, including underwater acceleration, upward leap, air glide and downward dive. When the dolphin goes through these four stages, the time history of its displacement

Hull girder damage degree identification by dynamic parameter change mainly solves the stiffness loss, while ship safety assessment mainly aims at strength loss issues. In this paper, a novel method is proposed to calculate strength loss based on stiffness loss. Section modulus is taken as the strength index to reveal that the stiffness loss of hull girder after damage is not always equivalent to its

Taking a T300k VLCC oil tanker as the research object, the ship route estimation model with minimum fuel consumption, CO2 emissions and shortest ETA as the objective function is established, which considers the weather conditions and constraints of the main engine rated power and safety comprehensively. On the basis of model verification, combined with the weather forecast data and the current maritime

The controllability and maneuverability of an Autonomous Underwater Vehicle (AUV) in practical applications need to be properly validated and assessed before the prototype is finalized for manufacturing. With regard to mathematical system model of the AUV, hydrodynamic coefficients have a dominant effect on the quality of vehicle pre-testing and evaluation, which is crucial to be estimated with adequate

Aiming at the problem that the exciting force induced by the propeller is excessive and the hull vibration noise exceeds certain limits for a certain surface ship, a type of triangular vortex generator is designed in this paper which is installed on the surface of ship stern to improve the quality of ship wake and solve the vibration problem. Firstly, the size and installing position of the vortex