bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Development of a Risk-Based Guideline for the Design of Current and Tidal Turbines
Authors: Macadré Laura-Mae , Paboeuf Stéphane , Dietenbeck Nicolas , le Diraison Stéphane 
Published: October 2015

Tidal turbines are emerging technologies offering a great potential by the harnessing of a renewable and predictable resource. However, exploitation at sea comes with significant design, installation, grid connection, and maintenance operations challenges. Consequently, guidelines and standards are required to ensure safety, reliability and quality for these innovative technologies, to support designers and to accelerate the development and commercialisation of the tidal technology. As tidal energy concepts are only at the demonstration stage, only few standards have been published about tidal and current turbines and no dedicated certification procedures have been developed so far.
The aim of this paper is to present a risk-based certification process developed by Bureau Veritas for tidal turbines and published in the Guidance Note NI603 Current and Tidal Turbines. Based on experience accumulated over the past years with tidal turbines technology developers, typical challenges related to the design and installation of tidal devices at sea will be highlighted in this paper. To support tidal turbines designers to take up these challenges, Bureau Veritas provides a decision-making guide gathering 1) recommendations from the existing experience at sea of tidal devices, 2) best practices from related sectors, such as shipping, wind energy or offshore oil & gas, 3) a risk-based approach to consider for the particular requirements of each tidal turbine installation.
In particular for tidal turbines, projects are highly site specific with huge impacts on farm layouts and foundation designs, to name but a few of the issues to be addressed. Paradoxically, the aim of certification societies is to develop rules and tools that can be applicable to a wide range of designs. Consequently, trying not to be design-specific, a proposal of a generic certification process is made in this paper. Existing certification principles from more mature sectors such as wind energy, offshore oil & gas or shipping have been adapted to the specificities of tidal turbines. This paper addresses different certification procedures such as prototype certification, component certification, type certification and project certification. Their respective application and interactions are developed, with a focus on prototype and type certification. In addition, particular attention is paid to the novelty induced by tidal turbines. Consequently, a risk-based guidance is provided to use qualification of new technology for the most innovative parts of the tidal device.
The Influence of the Ship’s Speed and Distance to an Arbitrarily Shaped Bank on Bank Effects
Authors: Lataire Evert , Vantorre Marc , Delefortrie Guillaume 
Published: October 2015

A displacement vessel — obviously — displaces a (large) amount of water. In open and deep navigation areas this water can travel almost without any restriction underneath and along the ship’s hull. In restricted and shallow waterways, however, the displaced water is squeezed under and along the hull. These bathymetric restrictions result in increased velocities of the return flow along the hull. The resulting pressure distribution on the hull causes a combination of forces and moments on the vessel. If generated because of asymmetric flow due to the presence of a bank, this combination of forces and moment is known as bank effects.
By far the most comprehensive and systematic experimental research program on bank effects has been carried out in the Towing Tank for Manoeuvres in Shallow Water (cooperation Flanders Hydraulics Research – Ghent University) at Flanders Hydraulics Research (FHR) in Antwerp, Belgium. The obtained data set on bank effects consists of more than 14 000 unique model test setups. Different ship models have been tested in a broad range of draft to water depth ratios, forward speeds and propeller actions. The tests were carried out along several bank geometries at different lateral positions between the ship and the installed bank.
The output consists of forces and moments on hull, rudder and propeller as well as vertical ship motions. An analysis of this extensive database has led to an increased insight into the parameters which are relevant for bank effects.
Two important parameters are linked to the relative distance between ship and bank and the ship’s forward speed. The relative position and distance between a ship and an arbitrarily shaped bank is ambiguous. Therefore a definition for a dimensionless distance to the bank will be introduced. In this way the properties of a random cross section are taken into account without exaggerating the bathymetry at a distance far away from the ship or without underestimating the bank shape at close proximity to the ship.
The dimensionless velocity, named the Tuck number (Tu), considers the water depth and blockage, and is based on the velocity relative to the critical speed. The latter is dependent on the cross section (and thus the bank geometry) of the waterway.
Software Analysis Tools for Wave Sensors
Authors: Morrison James , Christie David , Greenwood Charles , Maciver Ruairi , Vogler Arne 
Published: October 2015

This paper presents a set of software tools for interrogating and processing time series data. The functionality of this toolset will be demonstrated using data from a specific deployment involving multiple sensors deployed for a specific time period.
The approach was developed initially for Datawell Waverider MKII/MKII buoys [1] and expanded to include data from acoustic devices in this case Nortek AWACs. Tools of this nature are important to address a specific lack of features in the sensor manufacturers own tools. It also helps to develop standard approaches for dealing with anomalous data from sensors.
These software tools build upon an effective modern interpreted programming language in this case Python which has access to high performance low level libraries. This paper demonstrates the use of these tools applied to a sensor network based on the North West coast of Scotland as described in [2,3].
Examples can be seen of computationally complex data being easily calculated for monthly averages. Analysis down to a wave by wave basis will also be demonstrated form the same source dataset. The tools make use of a flexible data structure called a DataFrame which supports mixed data types, hierarchical and time indexing and is also integrated with modern plotting libraries. This allows sub second querying and the ability for dynamic plotting of large datasets.
By using modern compression techniques and file formats it is possible to process datasets which are larger than memory datasets without the need for a traditional relational database.
The software library shall be of use to a wide variety of industry involved in offshore engineering along with any scientists interested in the coastal environment.
Dynamics of a Marine Propulsion System With a Diesel Engine and a Propeller Subject To Waves
Authors: Taskar Bhushan , Yum Kevin Koosup , Pedersen Eilif , Steen Sverre 
Published: October 2015

When travelling in waves, the efficiency of the propulsion system is in most cases reduced, due to a variety of different effects. Traditionally, the performance of propeller and engine is analyzed separately. However, there might be important interaction effects, which this paper attempts to explore.
Engine and propeller models have been coupled to obtain realistic response of the propulsion machinery and to observe the effect of interaction between engine and propeller. Experimental wake data have been used in the simulations. The effects of different factors affecting ship propulsion in waves have been noted and their effects have been calculated separately to analyze the influence of each of the factors on ship operation.
A ship travelling in three different wavelengths of three different waveheights has been simulated. Influence of these waves on engine power and fuel efficiency has been studied. This paper is a step towards optimization of installed power through better prediction of sea margin with improved insights into the propulsion performance in waves.
Tubarão Martelo Field Riser System: Shallow Water Challenging
Authors: Ribeiro Elton J. B. , Tan Zhimin , Hou Yucheng , Zhang Yanqiu , Iwane Andre 
Published: October 2015

Currently the oil and gas industry is focusing on challenging deep water projects, particularly in Campos Basin located coast off Brazil. However, there are a lot of prolific reservoirs located in shallow water, which need to be developed and they are located in area very far from the coast, where there aren’t pipelines facilities to export oil production, in this case is necessary to use a floating production unit able to storage produced oil, such as a FPSO. So, the riser system configuration should be able to absorb FPSO’s dynamic response due to wave load and avoid damage at touch down zone, in this case is recommended to use compliant riser configuration, such as Lazy Wave, Tethered Wave or Lazy S.
In addition to, the proposed FPSO for Tubarão Martelo development is a type VLCC (Very Large Crude Carrier) using external turret moored system, which cause large vertical motion at riser connection and it presents large static offset. Also are expected to install 26 risers and umbilicals hanging off on the turret, this large number of risers and umbilicals has driven the main concerns to clashing and clearance requirement since Lazy-S configuration was adopted.
In this paper, some numerical model details and recommendations will be presented, which became a feasible challenging risers system in shallow water. For instance, to solve clashing problem it is strictly recommended for modeling MWA (Mid Water Arch) gutter and bend stiffener at top I-tube interface, this recommendation doesn’t matter in deep water, but for shallow water problem is very important. Also is important to use ballast modules in order to solve clashing problems.
Full Scale Flow Loop Experiments of Hole Cleaning Performances of Drilling Fluids
Authors: Ytrehus Jan David , Taghipour Ali , Sayindla Sneha , Lund Bjørnar , Werner Benjamin , Saasen Arild 
Published: October 2015

One important requirement for a drilling fluid is the ability to transport the cuttings out of the borehole. Improved hole cleaning is a key to solve several challenges in the drilling industry and will allow both longer wells and improved quality of well construction. It has been observed, however, that drilling fluids with similar properties according to the API standard can have significantly different behavior with respect to hole cleaning performance. The reasons for this are not fully understood.
This paper presents results from flow loop laboratory tests without and with injected cuttings size particles using a base oil and a commercial oil based drilling fluid. The results demonstrate the importance of the rheological properties of the fluids for the hole cleaning performance. A thorough investigation of the viscoelastic properties of the fluids was performed with a Fann viscometer and a Paar-Physica rheometer, and was used to interpret the results from the flow loop experiments.
Improved understanding of the fluid properties relevant to hole cleaning performance will help develop better models of wellbore hydraulics used in planning of well operations. Eventually this may lead to higher ROP with water based drilling fluids as obtained with oil based drilling fluids. This may ease cuttings handling in many operations and thereby significantly reduce the drilling cost using (normally) more environmentally friendly fluids.
The experiments have been conducted as part of an industry-sponsored research project where understanding the hole cleaning performance of various oil and water based drilling fluids is the aim. The experiments have been performed under realistic conditions. The flow loop includes a 10 meter long test section with 2″ OD freely rotating drillstring inside a 4″ ID wellbore made of concrete. Sand particles were injected while circulating the drilling fluid through the test section in horizontal position.
Validation of the Index to Determine Design Parameters of a WEC for the Cost Optimization of a Wave Farm
Authors: Okamoto Takashi , Fukaya Yutaro , Higo Yasushi 
Published: October 2015

An index to estimate the cost of electricity (COE) generated by a wave farm from the design parameters of a wave energy converter (WEC), such as the body size and the generator capacity, was examined to show the validity of index value in this study. The validation tests are performed for three different wave farm settings at three different locations.
The result displays the potential of index to capture the trend of COE value especially when the wave farm size is small. The calculation result of COE reveals that the parameter combination to give better profitability is determined by the balance between WEC construction fee and installation fee. So, it would be different from the optimum size to have the best energy conversion efficiency. It also explains the shift of parameter combination to give the better profitability when the size of wave farm is changed. However, the index contains certain level of error because of the lack of this feature. Therefore, the error becomes larger when the size of wave farm becomes larger. As a result, it was found that the modification of the index is needed to improve the accuracy by including the cost related to the number of buoys in the wave farm.
Reeling Pipeline Material Characterization: Testing, Material Modeling and Offshore Measurement Validation
Authors: Karjadi Erwan , Boyd Helen , Demmink Harm , Thibaux Philippe 
Published: October 2015

It is a fact that when a pipeline is installed by the reeling method, it will undergo cyclic plastic straining and the pipe will plastically deform. Due to the applied plastic bending moment, the residual deformation in terms of residual pipe ovality after reeling is difficult to predict by Finite Element Analyses (FEA) without a thorough understanding of the material characterization and changes under cyclic plastic straining.
The paper describes how the material behavior of seamless pipe under plastic strain reeling cycle has been characterized by a comprehensive material testing program including Bauschinger tests and perpendicular loading pre-straining tests. It turns out that for seamless pipe, by looking at the yield stress locus of the material after plastic straining, the reeled pipe material which initially shows isotropic behavior in the un-strained condition will change and evolve to show anisotropic behavior. The material in the hoop direction of the pipe will become more hardened than the material in the longitudinal direction of the pipe. The cross hardening characteristics of material under cyclic plastic deformation have been modeled using the “distortional plasticity” principle and implemented in a user subroutine of an FEA software package.
This paper includes the validation of the ovality prediction by FEA model using the developed material model against the ovality measurement from full scale bend tests at Heriot-Watt University as well as ovality measurements taken during the spooling test and trial of 16″OD pipeline at Carlyss spool base in 2013. The material testing of a sample cut out from Spoolbase test and trial, undergoes spool and un-spool 5 cycles, has been performed to confirm the distortional plasticity hardening behavior obtained from the small scale Bauschinger and perpendicular loading tests.
Drifting Paths of Disabled Vessels
Authors: Selvik Ørjan , Berg Tor Einar , Fathi Dariusz Eirik 
Published: October 2015

Many maritime emergency situations involve drifting vessels, and tools to predict drifting patterns have been developed by meteorology institutes, class societies and research companies. It is important to be able to predict a vessel’s drifting path and to estimate when it will drift into waters where grounding is a possible outcome. Such a prediction tool would provide valuable input to the planning of an emergency towing operation to prevent the vessel from grounding or to reduce the impact of the grounding.
In this paper we present the outcomes of a study that investigated the drifting pattern of a vessel with an engine shut-down in the Barents Sea. As part of the ongoing A-Lex project [1], MARINTEK has prepared a VeSim [2] model to investigate the drifting path of a cargo vessel. The outcomes of the study will be used to draw up a technical specification for work to be done to develop an improved ship drift model in Norwegian Meteorological Institute’s (MET Norway’s, [3]) new Halo platform [4]. An improved model will be of great help to those planning emergency towing operations and for positioning of emergency preparedness units with respect to the traffic situation (especially tracks of vessels carrying dangerous goods) and weather forecasts.
The Influence of the Mooring System on the Motions and Stability of a Semi-Submersible Floating Wind Turbine
Authors: Huijs Fons 
Published: October 2015

One of the main aspects of a floating offshore wind turbine design is its mooring system, which can strongly influence the floater stability and motions. This is illustrated by considering two catenary mooring systems for the same semi-submersible. The main difference between the two systems is the position of the connection points of the mooring lines on the floater, the so-called fairleads. The philosophy is that the design can be improved by shifting the fairleads to the highest feasible level.
For both mooring systems, the floater motions and stability are assessed. Stability curves are derived, taking both the effect of hydrostatics and the mooring system into account. Floater motions are analyzed using both uncoupled frequency domain calculations and coupled aero-hydro-servo-elastic time domain simulations.
The mooring system is found to have a considerable effect on the floating stability. The effect on the motions is less profound for the considered mooring systems and limited to the low frequency range. Mooring line tensions are however significantly affected by the fairlead position.
It is concluded that, with a well-designed mooring system, a smaller and thus less expensive floater can be used while still meeting the requirements in terms of stability and maximum motions. In addition, the mooring lines may be lighter as well.
An Efficient Time Domain Code for Strength and Fatigue Analysis of Steel Catenary Risers
Authors: Sidarta Djoni E. , Jing Xiaoning , Lambrakos Kostas F. , Burke Roger W. , Webster William C. 
Published: October 2015

Steel Catenary Risers (SCRs) are commonly used in the offshore industry. Strength and fatigue performance of SCRs due to waves, currents and vessel motions is typically calculated using time domain dynamic analysis. Strength analysis may involve a large number of load cases for different environments, riser conditions and vessel configurations. Fatigue analysis may involve computation of riser response for hundreds of fatigue sea-states. It is very important for project schedule and cost that the analysis software used is both accurate and computer efficient. This paper presents RodDyn as an alternative time domain analysis tool for SCR strength and fatigue analysis.
RodDyn is a finite element program for dynamic analysis of single-pipe risers. Several publications on this program are available in the literature. The results of dynamic analysis of an SCR for strength and fatigue from RodDyn are compared against the results from ABAQUS. ABAQUS is a general finite element program that has been widely used in the offshore exploration and production industry and has been considered one of the standard finite element programs. Riser dynamic analysis uses time series of vessel motions due to metocean environments at an oblique angle to the plane of the SCR. Von Mises stress per API RP 2RD, strength checks per API STD 2RD and fatigue damage along the riser are presented for both RodDyn and ABAQUS. Time series of effective tension and bending moments at selected locations on the riser are also compared.
The main advantage of using RodDyn for riser analysis is the speed of computation. This paper shows that RodDyn can deliver significant gains in computational speed compared to standard riser analysis software programs without sacrificing accuracy of the computed results.
Bed Shear Stress Distribution Around Offshore Gravity Foundations
Authors: Tavouktsoglou Nicholas S. , Harris John M. , Simons Richard R. , Whitehouse Richard J. S. 
Published: October 2015

Offshore gravity foundations are often designed with complex geometries. Such structures interact with the local hydrodynamics and generate enhanced bed shear stresses and flow turbulence capable of scouring the seabed or destabilizing bed armour where deployed. In the present study a novel bed shear stress measurement method has been developed from the camera and laser components of a Particle Image Velocimetry (PIV) system. The bed shear stress amplification was mapped out around six models of gravity foundations with different geometries. Tests were repeated for two bed roughness conditions. The structures tested included uniform cylinders, cylindrical base structures and conical base structures. The flow field around the models was also measured using PIV.
The results of this study reveal that the conical base structures generate a different hydrodynamic response compared to the other structures. For uniform cylinders the maximum bed shear stress amplification occurs upstream, at an angle of 45° relative to the flow direction, and measurements were found to agree well with numerical results obtained by Roulund et al. (2005). In the case of the cylindrical base structure the maximum amplification occurs upstream at a similar location to the uniform cylinder case. For the conical base structures the maximum amplification of the bed shear stress occurs on the lee side of the structure, with the magnitude dependent on the side slope of the cone. The bed shear stress results were validated against stresses derived from analysis of the flow fields obtained by the PIV measurements performed under the same test conditions.
Conclusions from the study are that the structure with the cylindrical base foundation produces the lowest bed shear stress amplification and that an increase in the bed roughness results in an increase in the amplification of the bed shear stress. These findings have direct implications for design of scour protection. In addition the flow reattachment point behind the foundation is dependent on pile Reynolds number (ReD). This suggests that the results of this study may be extrapolated for higher pile Reynolds using the method described in Roulund et al. (2006).