bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of an On-Board Wave Estimation System Based on the Motions of a Moored FPSO: Commissioning and Preliminary Validation
Authors: Simos Alexandre N. , Tannuri Eduardo A. , da Cruz José J. , Filho Asdrubal N. Queiroz , da Silva Bispo Iuri B. , Carvalho Rafaella C. A. 
Published: August 2013

This paper addresses the development, installation and initial tests of a system for wave spectra estimation from the measurements of the first order motions of a moored FPSO located in Campos Basin, Brazil. The estimation is based on Bayesian inference algorithms, previously validated by means of numerical and small-scale experimental analysis. A 6-dof inertial measurement unit (IMU) is used for monitoring the motions of the platform, and this information is sent to a remote data-base, also accessed by the wave-estimation system. The algorithm also requires the Response Amplitude Operators (RAOs), and they depend on the loading conditions of the FPSO.
A previous analysis considering typical loading configurations of the tanks showed that the wave estimation is mainly dependent on the total displacement of the vessel, and not on the load distribution among the tanks. Hence, the RAOs for the full-range of drafts (or total displacements) were numerically generated, considering a uniform distribution of the load among the tanks. Since the draft of the platform was not directly measured, the loading levels of the tanks are obtained from the automation system of the platform, and the draft is then estimated. Finally, the heading is measured by a gyrocompass, and it is necessary for the definition of the global wave direction. The Bayesian estimation is executed at time-spans of 30min. A parametric optimization algorithm is then applied for the calculation of the wave spectrum parameters from the raw-spectrum obtained by the Bayesian estimation.
A user-friendly interface was also developed, with on-line information about platform motions, estimated wave spectrum, peak statistics and data history. Since all information is accessed by network, the wave system can be installed either on-board or in the on-shore monitoring center.
The system was commissioned and a partial 3-month validation campaign was executed. The spectrum results were compared to NOAA estimates. As expected, low-period wave components (smaller than 8s) could not be estimated with accuracy, since the FPSO presents small motion response for these components. Swell and high-period wave components estimates presented good qualitative and quantitative agreement with satellite prediction.
Recent Experience in the Lateral Buckling Design of Medium to Large Diameter Pipelines
Authors: Branković Maša , Anderson Benjamin , Shim Edwin , Zeitoun Hammam , Chin Eu Jeen 
Published: August 2013

In the last decade and a half, the pipeline industry has gained significant experience in both the design and operation of pipeline systems exposed to lateral buckling. JIPs, design guidelines and recommended practices such as SAFEBUCK (Reference [1]), HOTPIPE (Reference [2]) and DNV RP-F110 (Reference [3]), together with operational feedback have significantly contributed to the development of comprehensive methods to determine robust lateral buckling design solutions. Most of this knowledge has been gained from understanding the behaviour of HP/HT (high pressure/ high temperature) small, light diameter systems, which buckle more predictably at operating conditions well below design conditions. Medium to large diameter, concrete coated pipelines are generally considered to be less prone to lateral buckling by comparison (due to expected milder design conditions), however the consequence of their buckling is far more severe and can prove extremely difficult to control.
Fundamentally, the knowledge acquired and general lateral buckling design methodologies developed for HP/HT systems can be applied for the design of larger, heavier pipelines, however there are a number of key differences in the behaviour of both systems which warrant special considerations.
Key considerations include (a), effective axial force and critical buckling force development (impacting susceptibility and initiation considerations), (b) severe post-buckle response on-seabed (impacting the acceptance of uncontrolled buckling for definition of buckle trigger spacing and extents), and (c), the consequence of introducing buckle triggers. Additional design complexity is introduced for systems installed in shallow water, which are exposed to more severe metocean conditions than deepwater HP/ HT systems. This requires heavy concrete weight coating (CWC) for stabilisation, resulting in strain localisation at field joints, concrete stiffening effects and complex interaction with hydrodynamic loading, typically ‘competing against’ intuitive global buckling design.
All of the above factors result in lateral buckling design solutions for medium to large diameter, concrete coated pipelines becoming rather challenging.
Natural Resource Exploration With Sonar on Underwater Vehicle
Authors: Sawa Takao , Kasaya Takafumi , Hyakudome Tadahiro , Yoshida Hiroshi 
Published: August 2013

Occurring as a set of 17 chemical elements in the periodic table, rare earth elements such as neodymium are necessary for the development of mobile phones and magnet motors. Although securing rare earth elements is essential for economic growth of all nations, their demand is rapidly expanding among global powers such as Brazil, Russia, India, and China. Rare earth element deposits were discovered in the seafloor near hydrothermal vents in the 1980s. Japan has the sixth largest exclusive economic zone (EEZ) and is abundant in underwater natural resources such as a cobalt and a manganese mine. Because underwater exploration of rare earth elements was deemed unprofitable, the practice was suspended. Current advancements in underwater robotics, however, have led to economic viability in this venture. Such developments have resulted in the increased use of remote sensing with sonars on unmanned underwater vehicles.
The Japan Agency for Marine-Earth Science and Technology (JAMSTEC) developed a cruising autonomous underwater vehicle (AUV) known as Urashima. This AUV performed its first sea trial in 2000, and cruise for 317 km without recharging or refueling in 2005 as a world record at the time. The first mission of Urashima was a vast sea exploration to investigate worldwide environmental crises such as global warming. However, the purpose of these missions has since then shifted primarily to the exploration of underwater natural resources. In addition, JAMSTEC developed a synthetic aperture sonar on a neutral buoyancy towfish in 2010. This underwater exploration system, known as Kyouryuu, scanned Wakamiko caldera at the sea bottom in Kagoshima Bay where volcanic activity was evident. Numerous hot-water flows from hydrothermal vents were clearly recorded. In addition, many dormant chimneys were detected. These features provide important data for estimating the distribution of hydrothermal vents and chimneys in addition to their transitions.
Ultra Heavy Wall Linepipe X65: Full Scale Severe Straining Sequences of Pipeline Strings
Authors: Di Vito Luigi , Lucci Antonio , Amato Stefano , Mannucci Gianluca , Tintori Federico , Crippa Stefano , Giugliano Paolo , Armengol Mariano , Darcis Philippe , Ruiz Eduardo , Pelcastre Mauricio , Mota Noé , Quintanilla Héctor 
Published: August 2013

Tenaris and Centro Sviluppo Materiali (CSM) are carrying out a Joint Industrial Project aimed at developing heavy wall line pipes. The suitability for very severe applications, involving high service pressures and temperatures, the latter causing large strain fluctuations, in presence of an aggressive sour environment, is analyzed both theoretically and experimentally, including small and full pipe models and tests.
The full project program aims at developing a new generation heavy wall product, supported by a comprehensive laboratory analysis of the material response under severe mechanical loading in aggressive environment and a full scale testing program, including both pipe and girth weld. Both investigations are mainly addressed to basic understanding of impact on design criteria of interaction between severe loading and aggressive environment. Four papers, [2], [3], [4] and [5], have been already presented, in previous OMAE conferences, on this project.
The present paper focusses on the full scale testing performed on strings of pipeline consisting of different pieces of pipe. In particular, two full scale testing have been performed applying the severe straining sequence defined as extreme in term of resistance against ratcheting, also involving plastic straining, as deduced in a previous work inside the project. The loading sequence was applied in global strain control, averaged on the whole string length, but necessarily the local distributions of strain differs in the three pieces of pipe. Analytical considerations are done about the expected straining behaviour and experimental results confirmed the theoretical considerations. The high strain hardening capability of the X65 steel pipes, metallurgically designed for strain based applications, guaranteed a good recovery of any non-homogeneity in straining, both during cycling that in larger axial deformation of the string.
During severe cycling in elastic-plastic regime in presence of pipe internal pressure, the strings demonstrated good resistance to ratcheting. In fact, due to the material capability to redistribute the cycling strains along the whole sample length, any section experienced limited ratcheting with unreversed circumferential expansion, during cycling, well within limits of tolerability. It is worth noting that, even in presence of severe cycling conditions, both on-shore type girth welds (SAW for double joint) and off-shore type (GMAW in Narrow Groove Bevel Preparation) preserved their integrity with no cracking or other damage.
Structural Reliability Applications in Design and Maintenance Planning of Ships Subjected to Fatigue and Corrosion
Authors: Câmara Marcos Corrêa , Cyrino Júlio C. Ramalho 
Published: August 2013

This paper presents structural reliability applications in design and maintenance planning for ships hull structures. For the assessment of structural strength, the model developed consists in an ultimate limit-state of hull-girder considering degradation by corrosion based in a statistical investigation of time-variant hull girder strength made by ABS (American Bureau of Shipping) on 2007. The time dependent reliability index obtained with the minimum elastic section modulus required by the rules of the classification society American Bureau of shipping (ABS), of two ship designs are compared against the results obtained from the target reliability index based design. The target reliability index assessment for corroded hulls is also showed. The monte-carlo simulation reliability method is used to calculate the time-dependent reliability of the primary hull structure.
Two approaches of fatigue and corrosion-enhanced fatigue time dependent reliability are developed. A long term stress range applied to a detail is fitted to a weibull distribution based in a known design life. A utilization factor is introduced in order to consider the fraction of time at sea. A risk-based inspection planning is discussed for commercial and naval vessels Both S-N curve and fracture mechanics based reliability methods are used and the results are compared. An example of reliability updating after a inspection result is showed.
Using a Simplified Smoothed Particle Hydrodynamics Model to Simulate Green Water on the Deck
Authors: Pakozdi Csaba , Stansberg Carl-Trygve , Skjetne Paal , Yang Wei 
Published: August 2013

Severe storms have gained more attention in recent years. Improved metocean data have led to new insight into severe wave conditions for marine design. Therefore, there exists an industrial demand for fast and accurate numerical tools to estimate the hydrodynamic loads during e.g. green water events.
Model tests generally play an important role in these studies. In the recent past, several practical engineering tools have also been developed, based on the experience from the experimental data bases in combination with simplified but still theoretical formulations. One such tool is Kinema2, which is based on non-linear random wave modeling combined with 3D linear diffraction theory to initially identify green water events, and then finally apply a simplified water-on-deck and slamming load estimation. This forms the background for the work presented in this paper which shows the feasibility of a new technique based on the Smoothed Particle Hydrodynamics (SPH). This method can give more detailed forecast of the hydrodynamics on the deck than the simplified water-on-deck estimation. SPH uses a Lagrangian framework (particles) to describe the fluid dynamics. The water propagation and kinematics of the green water events are, in this introductory stage of the study, reproduced by using a SPH inlet condition where particles are injected with given velocity from a curved rectangular area against the deck and the deckhouse. The relative wave height and water particle velocities found from KINEMA2. Numerical results for water elevation and velocity on deck are compared against model test time series and previous results from other numerical simulation methods. The present Lagrangian nature (compared to traditional Eulerian-VOF methods) can in principe significantly reduce the CPU demand and increase the simulation speed. Slamming pressures can then be calculated e.g. from simple slamming formula calculations. In principle, pressures can also be found directly from the SPH calculations, while this would demand a significantly larger number of particles which increases CPU demand of the SPH method.
Response Based Identification of Critical Wave Scenarios
Authors: Clauss Günther F. , Klein Marco , Soares Carlos Guedes , Fonseca Nuno 
Published: August 2013

In the last years the identification and investigation of critical wave sequences regarding offshore structure responses became one of the main topics in the ocean engineering community. Thereby the area of interest covers the entire field of application spectra at sea — from efficient and economic offshore operations in moderate sea states to reliability as well as survival in extreme wave conditions. For most cases, the focus lies on limiting criteria for the design, such as maximum global loads, maximum relative motions between two or more vessels or maximum accelerations, at which the floating structure has to operate or to survive. These criteria are typically combined with a limiting characteristic sea state (Hs, Tp) or a rogue wave. For the investigation of offshore structures as well as the identification of critical wave sequences, different approaches are available — most of them are based on linear transfer functions as it is an efficient procedure for the fast holistic evaluation. But, for some cases the linear method approach implies uncertainties due to nonlinear response behavior, in particular in extreme wave conditions.
This paper presents an approach to these challenges, a response based optimization tool for critical wave sequence detection. This tool, which has been successfully introduced for the evaluation of the applicability of a multi-body system based on the linear method approach, is adjusted to a nonlinear task — the vertical bending moment of a chemical tanker in extreme wave conditions. Therefore a nonlinear strip theory solver is introduced into the optimization routine to capture the nonlinear effects on the vertical bending moment due to steep waves acting on large bow flares. The goal of the procedure is to find a worst case wave sequence for a certain critical sea state. This includes intensive numerical investigation as well as model test validation.
On the Further Optimization of the “Green Water Concept” for Wave Energy Conversion
Authors: Helder Joop A. , Schmittner Christian , Buchner Bas 
Published: August 2013

This paper presents initial results from the following-up study of the ‘inverse’ or ‘green water concept’ for wave energy conversion. Initially presented in 2009, the ‘inverse concept’ was developed by MARIN as a vehicle for open discussion and exchange of ideas in the field of wave energy conversion. Pilot model tests presented in 2010 showed the great potential of the concept, but also revealed the challenges associated with Power Take Off design.
The present study aims to further optimize the inverse concept. A new PTO system has been incorporated, based on robustness and effective use of the structure’s (de)optimized hull. The resulting renewed concept combines maximized vessel motions with OWC-type of wave energy conversion.
This paper focuses on the motion response of the renewed concept. Frequency domain calculations show the response of the concept with water columns (moonpools) at the bow and stern. Remarkably, the already maximized motions of the hull become even more extreme when moonpools are incorporated. Special attention is given to the relative motions of the water inside the moonpools, as these give an indication of the wave energy conversion potential of the concept. The relative water motions inside the moonpools show a large response that is characterized by multiple peaks. This indicates the concept’s ability to convert energy in a wide range of sea states.
Results from additional diffraction analysis show that through proper tuning, the water columns inside the moonpools can be modeled as solid water-bodies. This allows for a future numerical modeling of the hydrodynamic interaction between structure, water columns, entrapped air and PTO damping in the time domain.
Targeting the Wave Resource From the Power Take-Off Perspective
Authors: MacCready Tyler , Paulos James , Zambrano Thomas 
Published: August 2013

Frequency dependence in a power take-off mechanism means that power generated does not have a one-to-one correspondence with power available in the waves. Viewing wave power resources from the perspective of the power takeoff device leads us to question the assumption that waves carrying the maximum power are the best target for resource development. We explore this power take-off perspective for a heave device fitted with an electric generator and find that power is preferentially produced from higher frequency waves.
While globally most wave power is concentrated in low frequency swells, when power production is dependent on velocity, as when driving an electrical generator, an energy-harvesting device gathers more power from higher frequency waves. We examine spectral data from the Pacific Ocean and the Gulf of Mexico and find that the peak frequency for heave velocity, and hence for power production, can be as much as twice the peak frequency of the resource power in the waves.
Furthermore, Response Amplitude Operator (RAO) considerations demonstrate the need for small, ‘nimble’ devices to access the most easily available wave power. We compare the total energy capture from the empirical wave spectra using devices tuned to different natural frequencies and find the most energy is captured, regardless of geographic location, with devices that have natural frequencies around 0.2 Hz, far above the swell frequency.
New Methods for Qualification Assisted Innovation Applied to a Practical Example
Authors: McGeorge Dag , Åhjem Vidar , Borg Jonas 
Published: August 2013

New technologies typically involve innovative aspects that are not addressed by existing normative standards and hence are not assessable through common certification procedures. To ensure that new technologies can be implemented in a safe and reliable manner, a specific kind of assessment is performed, which in many industries, e.g. the energy sector, is known as Technology Qualification (TQ). TQ aims at demonstrating with an acceptable level of confidence that a new technology will function within specified limits. DNV is currently developing a new method with application to Technology Qualification, drawing on the concept of assurance cases, based on a combination of function analysis originating from Value Engineering and argumentation logic used in safety cases. The method enables improved definition of the technology and where to focus when building confidence in it.
The method uses ‘Function Analysis’ that is structured towards what the system does instead of what it is. The focus on the functions encourages exploration of alternative ways by which the functions can be provided. Focus on functions draws attention to the system as a whole rather than each part the system consists of. This helps avoiding interface problems and may prove vital in an innovation process.
When the functions have been identified, one can proceed with analysing how a technical solution provides those functions. Those elements of the technical solution that represent proven technology can be dealt with by the conventional engineering processes and need not be included in the technology qualification process. Those elements assessed as new (or novel) are taken forward in the technology qualification process. This assessment is based both on the novelty of the function itself, the technical solution implementing it and the intended use of the technology in its intended environment. Confidence is demonstrated by first stating the goal of the qualification effort. Such a claim can be formulated as “The […] technology is fit for […]”. Then this goal is broken down into sub-goals. This is repeated till the lowest level claims can be directly justified by hard evidence. As an aid to overview and simplicity, such an argument structure (assurance case) can be presented graphically. The graphical assurance case can be readily communicated, reviewed and updated to reflect the needs and concerns of all stakeholders.
An on-going joint industry project for certification requirements to Deepwater Deployment and Recovery Systems will benefit from this improved method for qualification assisted innovation.
From Design to Installation of the 2nd Generation of Integrated Production Bundle Riser (IPB)
Authors: Decoret Laurent , Lecroq Gerald 
Published: August 2013

As part of the TOTAL E&P Angola (TEPA) PAZFLOR development, two 10” Integrated Production Bundle (IPB) flexible risers have been installed to connect the Pipe-In-Pipe Oligocene loop to the FPSO.
While IPB risers have first been implemented on the nearby DALIA development, the PAZFLOR IPB had to accommodate much higher design and operating temperatures. From the on-set of the project, focus was put on improving the design of this second generation of IPB and ensuring that all the lessons learnt from DALIA were addressed from a design, manufacturing and installation point of view. The paper presents the main elements of the IPB design as well as the comprehensive set of specific qualification tests performed during the course of the project. Indeed new materials were qualified, a new end fitting design for the bundle was implemented and various mechanical and thermal full scale tests were performed.
Both risers have now been successfully installed and commissioned further proving that IPB flexible risers are a technical and cost effective solution to address the flow assurance challenges of deep water production fluid recovery.