Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

OPTIMIZATION OF TWISTED RUDDER (With Bulb and Hub Cap)

This thesis has been carried out in close cooperation with the Fluid Engineering department of the DNV GL SE Maritime Advisory division in Hamburg. The main role of the Rudder consists not only on acting as a steering device and keep the ship on course, but also is a very signi cant energy recovery device when interacting with the wake from the propeller. Several studies have been performed in order to analyse the interaction effects between hull, rudder and propeller, assessing drag and manoeuvring characteristics from several geometries looking upon maximising the propulsive effciency. Twisted rudders in combination with rudder bulbs can improve propulsion effciency even by up to 4%. This master thesis consists in the implementation of a rudder optimization procedure with respect to overall propulsion effciency. More concretely a twisted rudder with costa bulb (and hub cap) evaluated utilizing a CFD process developed in the DNV GL SE facilities, coupling Reynolds-Averaged Navier-Stokes RANS method and Boundary Element method BEM. Solvers are the stationary OpenFOAM RANS simpleFoam and the unsteady BEM PROCAL. The use of this coupled method will reduce the computational time requirements compared to a fully RANS simulation. Thus the possibility of using an optimization routine (FS-Optmizer) to analyse different geometries for the Twisted Rudder, changing parameters in the CAD model created with CAESES Framework. The geometry is the Duisburg Test Case (DTC) which is a hull design of a typical 14000 TEU container ship in order to compare results to a real test case. A twisted rudder equipped with a Costa bulb is used, with a base symmetric pro le (NACA 0020 ); the twist goes from the top and bottom upon the bulb with a maximum angle of 15º along an axis located between 20% and 40% of the chord length. This document presents a flow work starting with the basic theoretical background, then a detailed description of the method, creation of the parametric model, mesh study followed by an initial non-twisted geometry assessment and in the end the optimization procedure description (for rudder and bulb), presenting final results, conclusions and recommendations

Numerical and analytical study of a spar-like floating offshore wind turbine impacted by a ship

It is estimated that Europe will develop 85% of the offshore wind needs in the North Seas. Moreover, floating offshore structures have been developed and installed in Scotland and other countries, this technology is still under development, with turbines that reach up to 12MW and more than 200 m diameter. Recently we have seen how a ship grounding can cause several problems to the economy world wide (with the Evergreen accident in the Suez canal 2021). This is the type of situations that we want to avoid when close to a wind farm, as the consequences of such collisions could include human lives loss or high environmental and economic issues. Design offces should always do a risk analysis before the installation of offshore structures. Normally Finite Element software are used to compute the resistance of an offshore wind turbine upon a collision with a ship. However, ship collisions involve several parameters (such as ship velocity, trajectory, mass and properties of the collided structure), which would mean the study of thousands of collision cases in order to find the worst scenario. Such studies would be time demanding and high computational resources are needed, which is not ideal in a pre-design stage. The purpose of the present thesis is to study, by means of Finite Element Methods, the energy dissipation modes of an spar-type Floating Offshore Wind Turbine and propose a simpli ed method to assess quickly the resistance of such structure after a collision with a ship. This proposal uses a combination of tools to calculate the different phases of the collision, including internal and external dynamics of the response. This can be an interesting way to identify the most critical collision scenarios for the impacted Floating Offshore Wind Turbine, and then use the powerful Finite Element Methods to analyse in detail the collision scenario chosen. The energy dissipation modes identi ed are namely: local crushing of the tubular tower, global bending of the whole structure and external dynamics, including hydrodynamic effects and mooring lines reaction. For the first two, the structure is considered as clamped at one end and closed-form expressions describing the evolution of the resistant force with respect to the ship penetration are presented, based on previous studies on ship-jacket structures collisions (for the modes involving cross-section crushing) and classical beam theory (based on the upper-bound theorem associated with a plastic limit analysis). For the mooring analysis, as the collision time is large in comparison to the mooring vibration modes, and the surge motion of the FOWT is small in comparison to its diameter, the simple quasi-static catenary equation is proposed, taking into account contact with the seabed. For the dynamic external response, the external dynamics calculator MCOL is proposed, as it solves the equation of motion taking into account the forces and moments calculated analytically during the contact. It has in consideration the hydrodynamic properties and wave response of the floating structure

Analytical method to assess the crashworthiness of a Floating Offshore Wind Turbine (FOWT)

With the purpose of using more renewable energies and the decarbonisation of EU, some European countries are implementing floating wind farms, which are closer to traffic lanes. It is important to have a complete scope of the structure’s response to a ship impact, in order to implement a risk assessment of the floating wind turbines. In this regard, finite elements solvers are widely used nowadays, which provide accurate results but are time-demanding, not suitable for an early design stage. A faster and reliable method is required in order to study a wide range of parameters: impact velocity, impact location, wind-wave-structure interaction, mooring system response and overall dynamics. This poster presents the methodology used to develop an analytical method to compute the crashworthiness of FOWT

Design methods to assess the resistance of Offshore wind Turbine Structures impacted by a ship

The dynamic modes of jacket, monopile and Floating offshore wind turbines (FOWT) after a collision event are presented. The authors have developed simplified analytical formulations based on plastic limit analysis to assess the resistance of an offshore wind turbine jacket impacted by a ship. For the case of collisions with monopile foundations and FOWT, the crushing behavior and structure dynamics are studied by means of finite element simulations. Numerical results for both monopile and floating structures will serve for further developments of simplified analytical tools, similar to that used for jacket structures

Optimización de Estructuras Navales y Offshore e Infraestructuras fluviales eficaces para apoyar el crecimiento económico global de un país / región

This paper is the written support of Prof. Ph. Rigo for his keynote lecture at the 5th International Congress for Ship Design and Naval Engineering (March 2017, Columbia). After presenting of the main research activities at ANAST, ULG, he discussed the way to improve the effectiveness of waterway infrastructures to support the global economic growth of a country/region. This paper includes the following parts: Ship Structure Optimization: methodology to perform ship scantling optimization, decreasing steel weight and keeping the production cost at an acceptable level. We first review the links between “Design” and “Optimization” and secondly define the place of “Ship Structure Optimization” within the general framework of a “Ship Optimization”. Ship impacts (Collision), with applications to navigation lock and dry dock gates: these gates have to be designed taking into account accidental loads, such as ship collisions. A new simplified analytical method is proposed, based on the so-called super-element method. This method was developed to rapidly assess the crashworthiness of the collided structure and avoid high computational effort of numerical simulations. Inland waterway Navigation and the development in South America of Inland Waterway Classifications. EMSHIP, European ERASMUS MUNDUS education program (www.emship.eu): the unique master in Ship & Offshore Structures awarded by the prestigious European Erasmus Mundus Program. Indeed, EMSHIP shares the outstanding experiences of educators, trainers, industrial partners and students in the rapidly developing areas of marine and offshore engineering industry

Structural Design Optimization—Tools and Methodologies: Volume 1: Optimisation of Ship Design and Operation for Life Cycle

peer reviewe

Numerical Crashworthiness Analysis of a Spar Floating Offshore Wind Turbine Impacted by a Ship

peer reviewedWith the new developments of floating offshore wind turbines (FOWT), wind farms are located in deeper water, meaning they are closer to traffic cargo and passenger lanes, increasing probability of colli-sion. This paper aims to analyze the crashworthiness of a spar FOWT by performing non-linear finite element simulations, which in the future will serve to validate a simplified analytical method for performing the same analysis in a faster and reliable way. The influence of parameters like nacelle mass, hydrodynamic forces, gravity, ballast mass and mooring line tension is analyzed. First simulations are run assuming a rigid striking ship in order to understand the crashworthiness of FOWT only. Then, the ship is modelled as deformable and the effect of bow deformability is investigated. Regarding internal mechanics, the main deformation modes are identified and deformation energies, structure indentations and resistant forces are post-processed. As ex-ternal mechanics is concerned, rigid-bodies motions during and after the collision are analyzed for different collision scenarios

Formulations analytiques pour évaluer l'énergie dissipée à la base d'un jacket d'éolienne offshore impacté par un navire

This paper presents some new analytical developments carried out to assess the energy dissipated plastically at the base of an offshore wind turbine jacket impacted by a ship. The jacket components involved in this mechanism are both the impacted leg and the rear leg, considered as clamped at the foundation level, as well as the horizontal bottom brace considered as rigidly fixed on the legs. The foundation system is assumed to be piles inserted into sleeves with cement grout. The base of the jacket is divided into four zones and a kinematically admissible displacement field is assumed for each of them. Based on plastic limit analysis, new analytical formulations are derived to assess the resistance and the dissipated energy for each considered area and therefore of the whole jacket base. To validate the method, full scale ship-jacket collisions are simulated both analytically and numerically and plastic energy dissipated at the base of the jacket is compared successfully with nonlinear finite element simulation results

Numerical Crashworthiness Analysis of a Spar Floating Offshore Wind Turbine Impacted by a Ship (influencing parameters)

•New floatingwindfarms •Deeperwater •Closertotrafficlanes •Regular maintenance •Higherriskof collisio