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1
Nakanishi, Laurel. "Offshore." FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3268.
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OFFSHORE is a collection of lyric essays that examines the intersections between human cultures and the natural world. The essays inspect issues of identity and belonging in different geographic, cultural, and political landscapes. Part one of the book centers on the cultural and natural landscapes of Hawaii and Japan. Part two explores interpersonal relationships in Montana. And part three focuses on social justice issues in Nicaragua and Florida. Each of the essays in this collection balances intellectual exploration with personal narrative and poetic description, allowing the essays to be simultaneously concept-driven while maintaining lyric force.
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Bossy, Philippine. "Offshore Gesellschaften." St. Gallen, 2009. http://www.biblio.unisg.ch/org/biblio/edoc.nsf/wwwDisplayIdentifier/04602132101/$FILE/04602132101.pdf.
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Theisen, Matias Ebbe. "Offshore-Grid." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14477.
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This thesis has been conducted in cooperation with the Norwegian transmission system operator, Statnett, and their research on two new interconnectors linking Norway to England and Germany. The work presented in this thesis has considered one of these interconnectors, with a third terminal connected offshore to allow for integration of offshore wind power and oil platforms, as shown in fig.~ref{fig:theGrid}.Investigation of the voltage source converters (VSCs) control ability as well as operational aspects of multi-terminal DC-grids has been performed. Identified as the key control variable of a DC-grid is the DC-voltage serving as a measure of power balance, since an unbalance will affect the DC-voltage through charging or discharging of the DC-capacitances. Utilizing VSCs allowing a fast and accurate control of the DC-voltage can lead to a stable operation of a DC-grid.The three-terminal structure, fig.~ref{fig:theGrid}, was implemented in the simulation tool SIMPOW and connected to a 35-node AC-grid model representing the Nordic grid. The simulation model was used for analyzes of the DC-grid operation and its affect on the connected AC-grids. The converter station connected to the Nordic grid were applied with DC-voltage control, implying that it will act as the power balancing unit of the DC-grid. The simulations performed show that the control structure implemented could assure a stable DC-grid operation within 0.3s of a fault. It identified the need for a fast response to changes in the DC-voltage as the influence of the other connected AC-grids were directly linked to DC-voltage oscillations. Simulations were also conducted to study the advantage of applying AC-voltage control compared to reactive power for the converter connected to the Nordic grid. It was identified that an increased stability of the Nordic grid could be assured during faults in the grid itself. This also affected the DC-grid operation through an increased capability of power exchange with the Nordic grid.
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Morozova. "OFFSHORE ZONES." Thesis, Київ 2018, 2018. http://er.nau.edu.ua/handle/NAU/33817.
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Brandsar, Jo. "Offshore Rankine Cycles." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19069.
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The title of the thesis - "Offshore Rankine Cycles" - is very general and cover a large range of engineering fields, e.g. thermodynamic cycles (Rankine, ORC, Brayton, Kalina, etc.), mechanical equipment (gas/steam turbine, heat exchangers and additional equipment) and safety concerns (flammable and/or toxic fluids, high temperature and pressures), to name the most important.The thesis try to give a brief overview of all critical points and alternatives, concerning employment of a waste heat recovery machine on offshore facilities, although focus has been on three more specified cases, namely:1. Comparison of a steam cycle vs. an organic Rankine cycle for high temperature operating conditions.2. Study of heat exchanger parameters on total cycle performance.3. Investigation of a modular expander setup versus a single expander.To compare a steam cycle to an organic cycle, a choice of working fluid for the organic cycle had to be made. After some investigation, toluene was chosen as it is a "common" fluid with known properties and was found to be a viable option for high temperature heat sources, both for subcritical and supercritical operation. Due to water being constricted to subcritical operation a CO2 cycle was implemented as a comparison to the supercritical toluene cycle. The main focus of the comparison was exergy losses during heat transfer and power output.The heat exchanger parameter study was conducted with a printed circuit heat exchanger as an example. The study of overall cycle performance has close connections to the heat exchanger size, since it is an important parameter concerning offshore employment due to costly "footprint". The cycle's dependency on the heat exchanger is mainly by the heat transfer rate, or heat load, which the heat exchanger applies to the cycle. The heat transfer rate is given by the heat exchanger`s ability to reduce the temperature of the exhaust gases. This ability depends on the two fluids involved and the geometry of the heat exchanger. While the choice in working fluid and pinch points sets the amount of heat transferred, the remaining analysis rest on the overall heat transfer coefficient (UA) to balance the heat load. When fluid properties are determined, the UA - value is again dependent on heat exchanger geometry and further variation of these parameters will in turn reveal the size of the heat exchanger. When imposing a working fluid to the cold side of the heat exchanger an optimization in heat exchanger volume could be found at specified heat load.A VBA macro has been made where expander parameters (rated power and efficiency vs. volumetric flow rate values) could be used as inputs to calculate the power output of two expanders in a modular setup relative to a single expander as reference.
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Chapman, Paul M. "Offshore marine visualization." Thesis, University of Hull, 2003. http://hydra.hull.ac.uk/resources/hull:6673.
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In 85 B.C. a Greek philosopher called Posidonius set sail to answer an age-old question: how deep is the ocean? By lowering a large rock tied to a very long length of rope he determined that the ocean was 2km deep. These line and sinker methods were used until the 1920s when oceanographers developed the first echo sounders that could measure the water's depth by reflecting sound waves off the seafloor. The subsequent increase in sonar depth soundings resulted in oceanologists finally being able to view the alien underwater landscape. Paper printouts and records dominated the industry for decades until the mid 1980s when new digital sonar systems enabled computers to process and render the captured data streams. In the last five years, the offshore industry has been particularly slow to take advantage of the significant advancements made in computer and graphics technologies. Contemporary marine visualization systems still use outdated 2D representations of vessels positioned on digital charts and the potential for using 3D computer graphics for interacting with multidimensional marine data has not been fully investigated. This thesis is concerned with the issues surrounding the visualization of offshore activities and data using interactive 3D computer graphics. It describes the development of a novel 3D marine visualization system and subsequent study of marine visualization techniques through a number of offshore case studies that typify the marine industry. The results of this research demonstrate that presenting the offshore engineer or office based manager with a more intuitive and natural 3D computer generated viewing environment enables complex offshore tasks, activities and procedures to be more readily monitored and understood. The marine visualizations presented in this thesis take advantage of recent advancements in computer graphics technology and our extraordinary ability to interpret 3D data. These visual enhancements have improved offshore staffs' spatial and temporal understanding of marine data resulting in improved planning, decision making and real-time situation awareness of complex offshore data and activities.
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Svensson, Niklas, and Martin Holmberg. "Offshore cable protection." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-34775.
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The market for renewable energy and an international power grid is constantly growing. This project has focused on the installation and protection methods for offshore power cables. Long distance cables over e.g. oceans and smaller distances within offshore wind farms. The focus is on three different materials for the protection task; concrete, cast iron and plastics. These materials have been evaluated in aspect to strength, life-length, reliability and environmental impact. Snapp products of Sweden AB have developed a cable protective pipe of polypropylene for offshore usage. This product and its opportunities are thoroughly investigated.
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Walsh, Bruce William. "Onshore/offshore transport mechanisms." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/28087.
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The onshore/offshore transport mechanisms are investigated. Careful and detailed observations of the surf zone are made to find any differences or similarities between the resulting flows caused by different breaking types. Emphasis is placed on the spilling and plunging breakers. Even though the physical breaking properties are significantly different, the time-averaged properties of the surf zone for each type of breaking wave are similar. Using this as a basis, a model of the beach is developed using a control volume that is bounded by the beach face, the time-averaged water level, and a vertical plane at the breaking point. The momentum acting on the control volume in the onshore and offshore horizontal directions is balanced.
The model shows that the onshore/offshore sediment transport is primarily dependent upon the magnitude of the wave setup shoreward of the breaking point, and the permeability of the beach. Increasing the permeability causes a reduction in the offshore net shear stress acting along the beach face which results in an increasing slope. Using this simple model, the difference between a gravel and sand beach can be explained, the gravel beach being steeper.
The model is used to calculated the offshore net shear stress for a plane impermeable beach in the laboratory. The calculation gives the right order of magnitude (<10 N/m2), but proves to be sensitive to small inaccuracies in the measurement of the setup.<br>Applied Science, Faculty of<br>Civil Engineering, Department of<br>Graduate
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Robinson, Michael E. "Statistics for offshore extremes." Thesis, Lancaster University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387465.
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Viertel, René, Gerd Tetzlaff, and Martin Kaltschmitt. "Offshore-Windenergie zur Stromerzeugung." Universitätsbibliothek Leipzig, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-218271.
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Der mittlere Wind in der atmospärischen Grenzschicht über den deutschen Nord- und Ostseegebieten unterscheidet sich gegenüber Landflächen durch höhere Windgeschwindigkeiten, eine stärkere Zunahme mit der Höhe und schwache Tages- sowie ausgeprägte Jahresgänge der Windgeschwindigkeit in Bodennähe. Neben diesen Vorteilen ergeben sich auch Nachteile im Hinblick auf die Windenergienutzung offshore. Das betrifft die Anforderungen an die Technik der Windstromerzeugung sowie wie die Messung und Prognose der relevanten meteorologischen Parameter. Nach Abschätzungen möglicher Flächen für die Windnutzung offshore und anlagentechnischer Möglichkeiten ist von einem enormen technischen Angebotspotenzial an Elektroenergie auszugehen, dem jedoch auch Beschränkungen seitens der Netzstruktur und Nachfrage entgegenstehen. Um das große Potenzial zur Stromerzeugung und Umweltentlastung nutzen zu können, sollte die Entwicklung in den kommenden Jahren im Bereich Windprognose, Anlagenbau, Regelungstechnik und Energiespeicherung zu weiteren Verbesserungen führen<br>The averaged wind in the Planetary Boundary Layer over the german North Sea and Baltic Sea areas shows some differences to the wind over land areas. There are higher wind speeds, a stronger increasing with height and slight daily and more distinctive annual variations of the near surface winds. Thats why the utilization of wind energy offshore has advantages. But also exists certain drawbacks in reference to technical requirements and the measurement and prediction of meteorological parameters. Estimations of suitable areas and technical prospects indicate a large technical offer potential of electric energy offshore, though additional restrictions must be considered. To make this potential of electric energy and environmental protection usable todays knowledge of systems and control engineering, energy storage and wind prediction should be improved in the coming years
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Viertel, René, Gerd Tetzlaff, and Martin Kaltschmitt. "Offshore-Windenergie zur Stromerzeugung." Universität Leipzig, 2004. https://ul.qucosa.de/id/qucosa%3A15278.
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Der mittlere Wind in der atmospärischen Grenzschicht über den deutschen Nord- und Ostseegebieten unterscheidet sich gegenüber Landflächen durch höhere Windgeschwindigkeiten, eine stärkere Zunahme mit der Höhe und schwache Tages- sowie ausgeprägte Jahresgänge der Windgeschwindigkeit in Bodennähe. Neben diesen Vorteilen ergeben sich auch Nachteile im Hinblick auf die Windenergienutzung offshore. Das betrifft die Anforderungen an die Technik der Windstromerzeugung sowie wie die Messung und Prognose der relevanten meteorologischen Parameter. Nach Abschätzungen möglicher Flächen für die Windnutzung offshore und anlagentechnischer Möglichkeiten ist von einem enormen technischen Angebotspotenzial an Elektroenergie auszugehen, dem jedoch auch Beschränkungen seitens der Netzstruktur und Nachfrage entgegenstehen. Um das große Potenzial zur Stromerzeugung und Umweltentlastung nutzen zu können, sollte die Entwicklung in den kommenden Jahren im Bereich Windprognose, Anlagenbau, Regelungstechnik und Energiespeicherung zu weiteren Verbesserungen führen.<br>The averaged wind in the Planetary Boundary Layer over the german North Sea and Baltic Sea areas shows some differences to the wind over land areas. There are higher wind speeds, a stronger increasing with height and slight daily and more distinctive annual variations of the
near surface winds. Thats why the utilization of wind energy offshore has advantages. But also exists certain drawbacks in reference to technical requirements and the measurement and prediction of meteorological parameters. Estimations of suitable areas and technical prospects indicate a large technical offer potential of electric energy offshore, though additional restrictions must be considered. To make this potential of electric energy and environmental protection usable todays knowledge of systems and control engineering, energy storage and wind prediction should be improved in the coming years.
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Ramtohul, Priya. "L'émergence des centres offshore." Montpellier 1, 2002. http://www.theses.fr/2002MON10046.
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Quels sont les facteurs expliquant l'émergence des centres offshore ? Quelles sont les caractéristiques des centres offshore et pourquoi ces centres se développent-ils principalement dans des micro-états ? La création d'un centre offshore contribue-t-elle au développement de ces micro-états ? Notre thèse se propose de répondre à ces interrogations. La première partie explore les facteurs favorables à l'apparition des centres offshore à partir des théories de la localisation industrielle et de la mobilité du capital. Nous présenterons dans une deuxième partie les caractéristiques générales des juridictions offshore et faisons une distinction entre centres offshore internationaux, régionaux et de domiciliation. Dans une troisième partie, nous évaluons l'impact des activités offshore sur l'économie des micro-états à travers une approche en données de panel et analysons l'avenir des centres financiers offshore dans le cadre de la convergence progressive des conditions onshore et offshore.
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Adedipe, Oyewole. "Integrity of offshore structures." Thesis, Cranfield University, 2015. http://dspace.lib.cranfield.ac.uk/handle/1826/9692.
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Corrosion and fatigue have been dominant degradation mechanisms in offshore structures, with the combination of the two, known as corrosion fatigue, having amplified effects in structures in the harsh marine environments. Newer types of structure are now being developed for use in highly dynamic, harsh marine environments, particularly for renewable energy applications. However, they have significantly different structural details and design requirements compared to oil and gas structures, due to the magnitude and frequency of operational and environmental loadings acting on the support structures. Therefore, the extent of corrosion assisted fatigue crack growth in these structures needs to be better understood. In this research, fatigue crack growth in S355J2+N steel used for offshore wind monopile fabrications was investigated in air and free corrosion conditions. Tests were conducted on parent, HAZ and weld materials at cyclic load frequencies similar to what is experienced by offshore wind monopile support structures. The seawater used for testing was prepared according to ASTM D1141 specifications and was circulated past the specimens through a purpose designed and built corrosion rig at a rate of 3 l/min, at a temperature of 8-100C and at a pH of 7.78-8.1. A new crack propagation method accompanied by constant amplitude loading was used. Crack growth rates in parent, HAZ and weld materials were significantly accelerated under free corrosion conditions, at all the stress ratios used compared to in air environment. However, in free corrosion conditions, crack growth rates in the parent, HAZ and weld materials were similar, particularly at a lower stress ratio. The results are explained with respect to the interaction of the loading condition, environment and the rate of material removal by corrosion in the weldments. A new model was developed to account for mean stress effects on crack growth rates in air and in seawater, and was found to correlate well with experimental data as well as with the other mean stress models tested.
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Raza, Muhammad. "Offshore grid control of voltage source converters for integrating offshore wind power plants." Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/461835.
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The offshore grid in North and Baltic Sea can help Europe to achieve 2020 and 2030 renewable energy target to counter climate changes . The formation of offshore grid requires the interconnection between several offshore wind power plants with multiple onshore grids. A voltage source converter based high voltage direct current transmission system is suitable to operate such an integrated offshore network. The offshore grid will enhance the trade between countries, provide better infrastructure for offshore wind power plants integration, and improve the energy market.
This thesis presents the control system design of voltage source converter to operate an offshore grid. The offshore grid is built gradually , starting from the integration of a single offshore wind power plan! till combined offshore AC and OC network in arder to perform the power system analysis associated with the networks such as steady-state power flow, dynamic behavior, network stability, and short circuit response. The research presents the method of determining control parameters with respect of power distribution and network stability requirements.
The research presents the frequency and voltage droop schemes to enhance the grid-forming mode of voltage source converter to operate in parallel in the offshore grid. A multi-objectives optimal power flow algorithm is proposed to determine the frequency and voltage droop gains in order to control the active and reactive power distribution among converters. Later, the impact of these droop gains on network dynamics and stability are analyzed. The study shows that the converter performance influences the offshore AC network stability in conjunction with the droops control loop.
Furthermore, a short circuit and frequency coordinated control schemes are presented for both offshore wind generation units and grid-forming converters . The frequency coordinated control scheme reduces !he wind power up to the maximum available export capacity after the disturbance in the offshore grid. lt is suggested that !he coordination control mus! have both frequency and over voltage control for improved transient response.
In the end, converter control of mullí-terminal OC network and its integration with the offshore AC network has been presentad. The research demonstrate the converter ability to control the distribution of power among the transmission system while ensuring the network stability. The finding of the research can be applied to derive the information and recommendation for the future wind power plants projects.<br>Las redes eléctricas marítimas en el Norte y en el Mar Báltico pueden ayudar a Europa a conseguir los objetivos para 2020 y 2030 de combatir el cambio climático. La formación de la red eléctrica marítima requiere la interconexión entre varios parques eólicos marinos con múltiples redes eléctricas en tierra.
Un convertidor de la fuente de voltaje basado en el sistema de transmisión de corriente directa de alto voltaje es el apropiado para poder operar una red marítima integrada. Las redes eléctricas marítimas aumentarán el comercio entre países, proveerán una mejor infraestructura para la integración de los parques eólicos marinos y mejorarán el mercado energético.
Esta tesis presenta el diseño del sistema de control del convertidor de las fuentes de voltaje para operar una red eléctrica marítima. La red eléctrica marítima se construye gradualmente, empezando por la integración de un solo parque eólico marino hasta la combinación de redes eléctricas marítima en CA y CD, esto para mejorar el análisis del sistema de potencia asociado con las redes, tales como el flujo de potencia en estado estacionario, el comportamiento dinámico, la estabilidad de la red y la respuesta en corto
circuito. La investigación presenta el método de determinación de parámetros de control con respecto a la distribución de potencia y los requerimientos de estabilidad de la red.
La investigación presenta los esquemas de frecuencia y la caída de voltaje para mejorar el método de formación de red del convertidor de la fuente de voltaje y operar en paralelo con la red eléctrica marítima. Se propone un algoritmo de múltiples objetivos para lograr un flujo de potencia óptimo, determinar las ganancias en la frecuencia y en la caída de voltaje y así lograr controlar la distribución de potencia activa y reactiva entre los convertidores.
Después, se analiza el impacto de estas ganancias en la dinámica y estabilidad de la red. El estudio nos muestra que el desempeño del convertidor influencia la estabilidad de la red eléctrica marítima en CA en conjunto con el lazo de control de la caída.
Así mismo, se presentan los esquemas de control coordinado de frecuencia y corto circuito, aplicados para las unidades de generación eólica marítima y los convertidores en red. El esquema de control coordinado de frecuencia reduce la potencia eólica hasta la máxima capacidad de exportación disponible después de las perturbaciones en la red eléctrica marítima. Se sugiere que la coordinación del control debe de tener control sobre la frecuencia y el sobre voltaje para mejorar la respuesta en transitorios.
Por último, se presenta el control del convertidor de las multiterminales en la red CD y su integración con la red eléctrica marítima en CA. La investigación demuestra la habilidad que posee el convertidor para controlar la distribución de potencia, junto con el sistema de transmisión, mientras se asegura la estabilidad de la red. Los hallazgos de esta investigación pueden ser aplicados para obtener información y recomendaciones en los futuros proyectos de parques eólicos.
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Haugsten, Hansen Thomas. "Offshore Wind Farm Layouts : Performance Comparison for a 540 MW Offshore Wind Farm." Thesis, Norwegian University of Science and Technology, Department of Electrical Power Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9990.
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<p>This master thesis has been written at the Department of Electric Power Engineering at the Norwegian University of Science and Technology. The work has been carried out at the Royal Institute of Technology in Stockholm, where the author spent the last year of his studies as an exchange student. In the thesis, six different designs of the electrical grid of a 540 MW offshore wind farm, placed 100km off the Norwegian coast, have been studied and compared. At this distance, AC cable transmission might be difficult because of the reactive power production in the cables. Taking this into consideration, two options for the transmission system to shore have been studied. In addition to the AC cable transmission, voltage source converter based HVDC transmission, in the form of HVDC Light, has been studied, giving a total of 12 models. The main scope of the thesis was to study the load flow situation and power system performance of the different offshore wind farm layouts. Two load flow cases were run for each model; the first studying the model when the active power transmission to shore was maximized, the second studying the model under a contingency situation. The reliability of the six designs was compared by calculating the expected number of cable failures during the life time of the wind farm for each design, and what consequence the disconnection of any cable would have on the power losses. In order to study the effect of the offshore grid design and transmission system design on the offshore power system stability, dynamic simulations have also been executed, and the voltage response and rotor speed response following a fault have been studied. All simulations have been executed in version 31 of the program PSS/E. The wind farm was modeled full scale, consisting of 108 wind turbines rated at 5MW. The wind turbines were modeled as doubly fed induction generators, using the generic wind model that comes with the program. The load flow simulations showed that an AC cable connection to shore gave lower total system losses than a DC connection for all designs. The lowest losses were found at the n-sided ring design in the AC/AC system, and the highest losses were found for the star design in the AC/DC system. These losses were 2.33% and 8.19% of the total installed capacity, respectively. In the dynamic simulations, a three phase short circuit fault, lasting 150ms, was applied at three different places in the system. The simulations showed that except from at the wind turbines that were islanded as a result of a fault, all dynamic responses were stable. The HVDC Light transmission to shore gave the highest voltage drops and the lowest voltage peaks offshore. Also, the maximum speed deviation was found to be larger when using HVDC Light transmission compared to using AC cables, with two exceptions; the radial and star designs when a fault was applied to the transmission system. A comparison of the six different grid designs showed that the results were varying. Based on the results in this thesis it has not been concluded that one of the offshore designs have better dynamic qualities than the other. The simulation results indicated that this is case specific, and more dependent on where in the offshore grid the fault occurs rather than the design of the offshore grid.</p>
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Stenvold, Torkjell. "Offshore Gravimetric and Subsidence Monitoring." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for petroleumsteknologi og anvendt geofysikk, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-5269.
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Tyrberg, Simon. "Offshore Surveillance of Wave Buoys." Thesis, Uppsala universitet, Elektricitetslära och åskforskning, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-109559.
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To gain further knowledge about the motion of the wave buoys involved in the Islandsberg project for wave power, a surveillance system has been designed. The base for the system consists of a lattice tower to be placed on one of two islets southwest of Lysekil: Klammerskären. The distance from the islets to the wave energy research park and the wave buoys is between 150 and 300 meters. The tower will be 12 meters high and in it a network camera will be mounted, together with a small wind turbine, two solar panels, a battery bank and equipment for communication with land. A signal cable presently dispatched in the sea near Klammerskären will be used to connect the islets to a measuring station at the nearby island of Gullholmen. All the necessary permits for the project have been acquired, all of the equipment to be used has been delivered, and the full procedures for the construction and installation of the tower and the surveillance system have been laid out. The tower however, has not yet been mounted and the system has not been tested as a whole. When completed, the tower may be used as a station for further measurements within the Islandsberg project.
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Sing, Sii How. "Marine and offshore safety assessment." Thesis, Staffordshire University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325972.
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Antoine, Rose-Marie Belle. "Legal aspects of offshore finance." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310194.
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Sahl, Thomas Alexander. "Advanced Positioning for Offshore Norway." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for petroleumsteknologi og anvendt geofysikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25962.
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Most of the computation involved in the planning of a new well is done by software. Software such as Landmark, Drilling Office X, etc. These softwares handle everything from the well placement to analysis of hydraulics, torque, and so forth for every drilled section of the well. The problem, however, is that they are closed systems with no insight to the procedure of the computation. And they are expensive, very expensive. This Thesis aims to build the foundation required for the position part of a drilling software. This is accomplished by explaining in detail the field of geodesy and map projections and the associated formulae, with special considerations for the area offshore Norway. Once the guidelines for transformation and conversion have been established, the formulae are implemented in MATLAB. All implemented functions are then verified, for every conceivable method of operation. After which both the limitation and accuracy of the various functions are discussed. More specifically, the iterative step required for the computation of geographic coordinates, the difference between the North Sea Formulae and the Bursa-Wolf transformation, and the accuracy of Thomas-UTM series for UTM projections. The conclusion is that the recommended guidelines have been established and implemented. The implementation was verified, and the proper handling of information is suggested. It also concludes that all functions are more than accurate enough for drilling purposes, and that there is a clear difference between using the Bursa-Wolf transformation and the North Sea Formulae. The difference is discussed in detail, and a intersecting area near the 62$^{\circ}$N is found with 4 meters or less deviation. There are multiple areas on which to continue the work carried out on this Thesis. Within the field of Geodesy, it is suggested that work is done to map the transformations used worldwide, and implement these with the appropriate selection criteria for automation. Attempting to find a joint transformation for the North Sea and the Norwegian Sea would also be recommended. This transformation should replace both the North Sea Formulae and the Bursa-Wolf transformation. Within the field of Map Projection, it is suggested that the conversion of coordinates is expanded to include the MGRS system, the UK grid system, and implementation of the Kr{\"{u}}ger-n series of 8$^{th}$ order for UTM coordinates. Lastly, it is suggested that a graphical interface is developed for both current and future models. This interface should serve as a prototype for a final drilling software.
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Stepenskyi, E. I. "Offshore zones in international business." Master's thesis, Sumy State University, 2019. http://essuir.sumdu.edu.ua/handle/123456789/75550.
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У кваліфікаційної магістерської роботі досліджено фінансовий механізм функціонування офшорного бізнесу, проаналізовано позитивні та негативні наслідки використання офшорних схем як у світовій практиці, так і в Україні зокрема, а також сформульовано пропозиції щодо основних напрямів вдосконалення регулювання офшорного бізнесу.<br>In the qualification master's work I investigated the financial mechanism of offshore business functioning , the positive and negative consequences of using offshore schemes both in the world practice and in Ukraine in particular are analyzed, as well as proposals on the main directions of improvement of offshore business regulation are formulated.
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Palatinus, Peter. "Návrh příhradového výložníku offshore jeřábu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229735.
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This master`s thesis deals with the design of an offshore crane jib with maximal safe working load 80 tons and maximal radius 45 meters. The design consists of a design solution of the steel construction and a stress analysis of its FEM model, which was performed using NX I-deas software according to the requirements and specifications of the Huisman company. This thesis includes source materials for drawing documentation.
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Fuglem, Mark. "Decision-making for offshore resource development." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ34246.pdf.
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Uraz, Emre. "Offshore Wind Turbine Transportation & Installation Analyses Planning Optimal Marine Operations for Offshore Wind Projects." Thesis, Högskolan på Gotland, Institutionen för kultur, energi och miljö, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-217007.
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Transportation and installation of offshore wind turbines (Tower, Nacelle and Rotor) is a complete process conducted over several phases, usually in sequence. There are several factors that can turn this process into a challenge. These factors can either be due to offshore site conditions or the technical limitations of the installation vessels. Each project has its own characteristic parameters and requires a unique optimum solution. This paper identifies the dynamics of the installation process and analyzes the effects of each phase on the progression of events.The challenges in wind turbine installations due to offshore environment were investigated, the effects of each were explained and their significances were stressed. Special installation vessels were examined and their technical specifications were analyzed in terms of working conditions, dimensions, service performances, and crane capacities as well as projecting future design trends. Several offshore wind farm projects were analyzed; their installation methods were specified, and compared to each other to determine advantages and disadvantages of different pre-assembly concepts. The durations of the sub-phases of the process were defined in terms of different variables such as site conditions and individual vessel performance. These definitions were used for making time estimations, and conducting further analyses regarding the effects of different site specific parameters on the overall project duration.In conclusion, this study considered the main operation parameters in an offshore wind turbine installation context: the benefits and drawbacks of different pre-assembly methods were researched and evaluated resulting in new knowledge and a productive contribution for optimizing “the offshore turbine transportation and installation process”, based on actual time usage.
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Nadeem, Shehzad. "Dead ringers globalization and the paradoxes of development and identity /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3303720.
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Thesis (Ph. D.)--University of California, San Diego, 2008.<br>Title from first page of PDF file (viewed June 13, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 218-236).
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Acheampong, Theophilus. "Essays on North Sea oil and gas economics : offshore safety economics and third party access to infrastructure in the upstream oil and gas industry." Thesis, University of Aberdeen, 2017. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=232397.
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This thesis explores two themes on upstream oil and gas economics centred on offshore safety economics and third party access to infrastructure in the United Kingdom Continental Shelf (UKCS). The first part involves work that explores the nexus between the offshore safety regime and safety outcomes. It contributes to the literature by explaining the post-Piper Alpha safety regime changes with regard to our understanding, framing of safety decision making and benchmarking of safety outcomes. The second part investigates third party access to infrastructure issues in the UKCS. It contributes to our understanding of how different third party access to infrastructure arrangements can be utilised to maximise economic recovery. Each chapter addresses fundamental issues of North Sea oil and gas operations through the application of microeconomic, operations research and econometric methods within a formal analytical framework. The results provide insights into decision-making complexities in the upstream oil and gas industry by guiding policy makers. Specifically, part one of this thesis looks at safety performance in the post-Piper Alpha era in the UKCS. It investigates ways through which a more comprehensive and theoretically informed framework can be used to understand the linkages that arise when dealing with safety regulations and their impacts on the offshore oil and gas industry. Our objective is to empirically ascertain the determinants of offshore hydrocarbon releases within the context of the post-Piper Alpha offshore safety regime regulations. This is done using an observed number of hydrocarbon releases linked to a population denominator data of the number of the installations present in the UKCS. Three research problems are examined: (1) the transmission mechanisms through which safety regulation influence firm and industry productivity; (2) the assessment methods utilised in measuring and benchmarking regulatory outcomes in terms of safety compliance; and (3) the extent to which safety policies contribute to enhancing safety levels in the oil and gas industry. We initially review the background and literature on offshore safety with a particular emphasis on the UKCS in Chapter 2. We also frame our research questions and underlying hypothesis here. In Chapter 3, we present our underlying empirical framework and model specifications followed by some descriptive analysis of the hydrocarbon releases data. The results of the various econometric model specifications are analysed in Chapter 4. The second part of the thesis explores how possible different ownership patterns (including access arrangements) might affect the economic viability of exploiting remaining resources in the UKCS. This section attempts to answer two critical questions namely how the impact of the separation of infrastructure and field ownership affect economic recovery and the impact of taxation on field and hub economics in a mature oil basin. We explore how possible different ownership structures and access arrangements might affect the economic viability of remaining UKCS reserves. We apply a mixed integer programming (MIP) model to field data from the Northern North Sea. Specifically, we examine how the unbundling of infrastructure and field ownership, as well as different cost sharing and tariff arrangements, affect the long-term economics of hubs and their user fields. Regarding the layout, Chapter 5 talks about access to infrastructure issues in the UKCS namely the regulatory framework for access and related legislation. It leads to the development of a conceptual framework and model based upon which extractions are made to capture the various potential market outcomes. In Chapter 6, the empirical model, which utilises the mixed integer programming approach, is discussed. The data sources and characterization, as well as the presentation of the results from the Baseline Model, are presented in Chapter 7. The analysis of the Tax Model and the Cost Sharing plus Tax Model including structure and simulated results with underlying assumptions are presented in Chapter 8. Finally, Chapter 9 leads to a thorough discussion of the results followed by conclusions and policy recommendations.
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Pouliquen, Patricia. "La condition des travailleurs de l’off-shore." Brest, 1993. http://www.theses.fr/1993BRES5001.
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Le but de cette thèse a été de présenter la condition juridique et la protection sociale des travailleurs de l'offshore. Ainsi, dans une première partie, il a été examiné les protagonistes de la relation contractuelle à savoir l'employeur aux visages multiples et le salarié au statut ambivalent : certains personnels ont le statut de marin, d'autres sont des travailleurs terrestres, le plongeur connaît également un statut particulier. Ce statut particulier s'explique par le lieu de travail original de ces personnels : les structures offshore dont les variétés sont les plus diverses. Il a également été envisagé le droit applicable à la relation contractuelle dans la mesure où le départ du personnel offshore est régi par des normes matérielles internationales élaborées par les sociétés offshore. Mais cela n'exclut cependant pas les conflits de lois ou de juridiction susceptibles d'intervenir, d'autant plus que ce personnel peut évoluer dans les zones échappant à la souveraineté de l'état côtier. Dans une seconde partie, il a été examiné la protection sociale des travailleurs de l'offshore. Ce personnel travaillant dans la majorité des cas hors du territoire national, il a fallu relativiser le principe de territorialité de la protection sociale par des mesures nationales mais aussi communautaires, valables aussi bien pour les travailleurs terrestres que pour les marins. Quant à la réparation des risques professionnels, les marins connaissent un régime quelque peu différent de celui des travailleurs terrestres<br>The goal of this thesis has been to present the legal conditions and social welfare of off-shore workers. Therefore, the main players have been studied in their various roles; from the many-faced employeurs to the ambivalent nature and status of the personnel. Certain workers are considered to sailors, oters land-side workers and even divers have their own particular category. The enormous variety of jobs and job duties explains the creation of highly individual work categories. It has also been noted that in cases of resignation, the contract law applicable is based upon international norms which are then adapted by the off-shore companies. This however does not eliminate all conflicts of jurisdiction, particularly as the off-shore personnel can excluded from those under the jurisdiction of coastel law. Secondly, the social welfare of off-shore workers has been examined. As the large majority of off-shore personnel work outside national territories, the definition social welfare jurisdiction has had to be redefined by national and communal mesures which cover both land workers and sailors. As to the claims for professional risks. The sailors coverage differs very little from the land workers. The status of a salaried employee on detached service and that of an expatriate salaried employee must also be taken into account
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Toselli, Eleonora. "Metodi di posizionamento di strutture offshore." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
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Nel presente elaborato vengono approfonditi i principali metodi di posizionamento attualmente utilizzati, ossia il GPS e il GPS differenziale, con particolare riferimento a strutture posizionate in mare. Gli stessi sono utilizzati per il monitoraggio della subsidenza e dei movimenti tettonici cui le strutture offshore sono soggette, che, essendo movimenti dell’ordine di qualche millimetro all'anno, richiedono accuratezza nelle misure. Nell'ultima parte della tesi si è provveduto ad analizzare una serie di dati, derivanti da rilevamenti GPS, al fine di valutare gli effetti termici sulla struttura emersa di una piattaforma offshore.
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Valpiani, Giovanni. "Welding Book of an Offshore Jacket." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15255/.
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La tesi riguarda la redazione del "Welding Book" per il caso studio di un Jacket Offshore. Il corpo del testo è costituito da una breve introduzione sulla saldatura e sul progetto che è stato preso in considerazione per realizzare il Welding Book. Una seconda parte teorica con richiami alle normative e specifiche utilizzate, riguardante le nozioni necessarie per realizzare il libro di saldatura. Una terza parte tecnica che racchiude il Welding Book; in particolare un elenco di tutte le saldature da effettuare nel progetto, le WPS (Welding Procedure Specification) e le WPQR (Welding Procedure Qualification Records). Concludendo i disegni del Jacket Offshore e i dettagli costruttivi delle saldature.
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Stene, Torkild Laurin Kamsvåg. "Valg av driftsalternativ for kompressorer offshore." Thesis, Norwegian University of Science and Technology, Department of Energy and Process Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-10341.
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Flo, Randi Aardal. "Configuration of large offshore wind farms." Thesis, Norwegian University of Science and Technology, Department of Electrical Power Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9957.
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<p>This master thesis is written at the Department of Electric Power Engineering at the Norwegian University of Science and Technology. The work has been carried out at NTNU in Trondheim. The thesis deals with configuration of large offshore wind farms and transmission systems, and is a continuation of the project written during the autumn 2008. Today several plans on 1000 MW offshore wind farms exists. The size of the wind farms has led to a challenge of how to find an efficient and secure design of the overall system. The system has to be cost-effective in order to compete with other forms of power generation. In this study, costs is not considered. The purpose of this thesis was to study different transmission systems and configuration of an 1000 MW wind farm located 75 km from shore. The optimal distance between the turbines is a compromise between wake effect, wind farm are and cable lengths. To perform a detailed study of wake effects and optimal spacing, computer programs like WindSim would be necessary. Three common wind farm configurations is radial, star and ring layout. The selection of layout depends on costs, wind data and the wind farm area. Various wind turbine systems have been developed and different wind generators have been built. According to the survey of different wind generator system and considering the grid connection requirements on wind turbines, the developing trends of wind turbine generator systems shows that variable speed is very attractive and concepts with full-scale power converters will become more attractive. In this thesis two wind farm configurations with different transmission system were further studied. AC/AC, AC/DC and DC/DC are possible transmission systems. In this thesis AC/AC and AC/DC were compared. The selected layout of the wind farm was the radial layout. Number of strings was 35, with eight turbines in each string. Each wind turbine could produce 3.6 MW, which gives a total generation of 1008 MW. The two configurations were modeled in PSS/E. Siemens has made a model called WT3 that was developed to simulate performance of a wind turbine employing a doubly fed induction generator (DFIG). The model was developed in close cooperation with the GE Energy modeling team. This model was used in this thesis. For the dc transmission the HVDC Light from ABB was used. Two different disturbances were applied. One at the connection point at shore, and one at the connection point for all the radials. The load flow results shows that the losses are 5.8$%$ higher in the AC/DC system. The dynamical result shows that both of the systems were stable, and fulfill the grid code requirements. The results indicates that the short-circuit MVA is higher in the ac system than in the dc system. After a fault the voltage recovery was more smoother in the dc system, and the voltage recovery time were shorter.</p>
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Mathisen, Sindre. "Design criteria for offshore feed barges." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18480.
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The fish farming industry faces some problems for the future as the escaping of fish and fish lice. One solution to these problems could be to move the farms further offshore. The main focus of the industry is on the cages the fish is held in, but the feed barge is the brain of a fish farm. Before offshore fish farming is an acceptable solution for the future the design criteria for the feed barge has to be sufficient for more exposed areas.Some regulations both for fish farming and the oil industry have been evaluated. The conclusion from the evaluation of the regulations is that the regulation for floating fish farms is the least strict regulation. The purpose of this report is to enlighten the need for new thinking for design criteria for offshore feed barges by doing a hydrodynamic analysis in HydroD by using WADAM and potential theory applied to a panel model. The computer program is a recognized program developed by DNV. The model in this report is a design which is believed to be the best design for exposed areas. The model is analyzed in both hydrostatic and hydrodynamic conditions. The hydrostatic analyses conclude that the barge is stable and valid for operation in Norwegian waters. For the hydrodynamic analysis it as assumed two different locations with different wave data to enlighten the need to design a barge to a specific location. There is also assumed extra restoring as simulation of mooring. The result from the hydrodynamic analyses is used to evaluate the required freeboard for each location and the motions and accelerations of the barge. The results show that the barge in both locations will experience water on deck already for significant wave height of 2 meters, which actually is low even for the regulations today. The rotation and acceleration results are compared against limits for human tolerance and they show that there is a need for evaluating this in the design criteria.The conclusion is that the regulation valid today for fish farming is insufficient for offshore fish farming and that it is possible to look towards the offshore industry for leads on how the regulations should be formed. For the future it would be appropriate to change the design criteria and design of the feed barge if the fish farming is to be moved further offshore.
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Brekke, Øystein. "Modular Capabilities on Offshore Support Vessels." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18568.
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The report is divided into three different categories; background, concept evaluation and comparison and the methodology development. The background gives a short introduction of product architecture, modularity and modularization and also a brief description of existing design concepts which are capable of offering modular capabilities in the operation phase of a vessels life cycle.The second part of the report is a review of possible advantages and disadvantages with the implementation of a similar concept as presented in the background on offshore support vessels. The review deals with several aspects such as increased flexibility, higher spot utilization and also how this concept can have effects in an environmental perspective. Direct challenges with modular capabilities such as equipment complexity, port logistics issues etc. has also been discussed. Finally the concept is evaluated from an economical perspective, discussing costs in short and long term perspectives and how to predict the costs of a conversion between operations.The result of the evaluation is that the concept has aspects that are presumed quite beneficial for ship owners. Noticeable are increased flexibility in the range of operations a vessel can perform, possibilities for a fleet reduction due to modular capabilities and also possibilities for economic benefits in forms of higher spot utilization and easier maintenance of equipment modules. It is also anticipated that the concept will make the vessel more receptive for new technology and equipment modules. The most repressive aspect regarding modular capabilities is by far each equipment modules high degree of complexity together with the low degree of independency.The concept has also been compared with multi-purpose OSV’s and conventional mission specific OSV’s within several different aspects considered important for ship owners. The results are generally favoring a vessel with modular capabilities, but also that the negative aspects of the concept might not be taken sufficient account for in the comparison.In the third and last part it is developed a methodology to establish the equipment structure of an offshore support vessel with modular capabilities. It establishes the function hierarchy of the vessel and defines the interactions between the equipment modules and the functions before each module is evaluated in light of modular complexity and vessel influence. Based on this the equipment structure is established and exchange intervals for the modules are proposed.To illustrate the steps of the methodology better a case study is performed based on 5 different operations; anchor handling, towing, pipe lay, construction and support. The case study gives two main indications:1. There are a potential in further development of the methodology. Mainly involving the modules interactions and the specific equipment evaluation.2. The equipment modules are as determined before very complex and require long exchange intervals and also extensive external support to swap modules.
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Hodgkinson, Derek Anthony Martin. "Computer graphics applications in offshore hydrodynamics." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26705.
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The results of hydrodynamic analyses of two problems involving offshore structures are displayed graphically. This form of presentation of the results and the liberal use of colour have been found to significantly help the ease in which the results are interpreted.
For the transformation of waves around an artificial island, a time history of the evolution of the regular, unidirectional wave field around an artificial island is obtained. Through the use of colour, regions in which wave breaking occurs have been clearly defined. The numerical technique used is based on the finite element method using eight noded isoparametric elements. The determination of the transformed wave field takes wave breaking, wave refraction, diffraction, reflection and shoaling into account. The graphical display is achieved by using a plotting program developed for the output of finite element analyses.
The motions of a semi-submersible rig are computed from the RAO curves of the rig, used to obtain its' small response in a random sea. The numerical technique used in the analysis assumes that the vertical members are slender and may be analysed using the Morison equation whereas the hulls are treated as large members which are discretised and analysed using diffraction theory. The discretisation of the cylinders and hulls together with the time history of the rig's motions are displayed graphically. Once again, the graphical display is plotted using a program developed for the output of finite element analyses for four noded elements. In this case, a finite element technique has not been employed but the results were ordered to act as though this is the case. The slender members (cylinders) and large members (hulls) are clearly distinguishable by using different colours. The elements used in the analysis are also clearly shown.
The VAX 11/730 system was used to obtain the results shown. A video tape, using the results of a time stepping procedure, was made by successively recording the hardcopies produced by the VAX printer. The time stepping could also be seen, in real time, on the IRIS.<br>Applied Science, Faculty of<br>Civil Engineering, Department of<br>Graduate
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Mtango, Prosper. "Using Scrum in offshore software projects." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-67518.
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Due to its growth at exponential rate offshore software development has become a common way of producing software by software organizations from highly industrialized countries in Europe and North America. Previous studies have revealed that some of these organizations use agile project management frameworks in managing and running their offshore software projects. Blending agile principles and offshore software development appears to raise a contradiction as the two notions have opposite characteristics. This research focuses the implementation of agile project management frameworks such as Scrum in offshore software projects. The research project was performed by reviewing relevant literature and analyzing the results obtained from the interviews conducted to Cambio Healthcare Systems AB, a Swedish software company that offshore its software projects with Creative Technologies Pty Ltd located in Sri Lanka. The interviews were conducted to Swedish based staff involved in offshore software projects with their Sri Lankan partners. The research findings indicate that offshore software development is a challenging business and requires close monitoring to minimize its challenges. Some of the challenges include dispersion, loss of communication richness and cultural differences between the parties involved. Moreover even though the agile project management frameworks and offshore software development principles differ in nature, the findings have revealed that software organizations such as Cambio make use of these differences to minimize the challenges they face in their respective offshore software projects. The main conclusions drawn from this research is that there is not much evidence that the application of agile project management frameworks such as Scrum is feasible enough to combat the challenges. This research suggests for further research studies to collect information from staff in both offshore and onshore sites in order to formulate enough evidence on whether to apply these strategies or not.
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Sinha, Yashwant. "Optimisation of offshore wind farm maintenance." Thesis, Robert Gordon University, 2016. http://hdl.handle.net/10059/1572.
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The installed capacity of European Offshore Wind Turbines (OWT) is likely to rise from the 2014 value of 7GW to 150GW in 2030. However maintenance of OWT is facing unprecedented challenges and cost 35% of lifetime costs. This will be equivalent to £14billion/year by 2030 if current OWT maintenance schemes are not changed. However the complexities around OWT operation require tools and systems to optimise OWT maintenance. The design of optimal OWT maintenance requires failure analysis of over 10,000 components in OWT for which there is little published work relating to performance and failure. In this work, inspection reports of over 400 wind turbine gearboxes (source: Stork Technical Services) and SCADA data (source: Shetland Aerogenerators Ltd) were studied to identify issues with performance and failures in wind turbines. A modified framework of Failure Mode Effects and Criticality Analysis (i.e. FMECA+) was designed to analyse failures according to the unique requirements of OWT maintenance planners. The FMECA+ framework enables analysis and prediction of failures for varied root causes, and determines their consequences over short and long periods of time. A software tool has been developed around FMECA+ framework that enables prediction of component level failures for varied root causes. The tool currently stores over 800 such instances. The need to develop a FMECA+ based Enterprise Resource Planning tool has been identified and preliminary results obtained from its development have been shown. Such a software package will routinely manage OWT data, predict failures in components, manage resources and plan an optimal maintenance. This will solve some big problems that OWT maintenance planners currently face. This will also support the use of SCADA and condition monitoring data in planning OWT maintenance, something which has been difficult to manage for a long time.
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Yeow, Kervin. "Three dimensional scour along offshore pipelines." University of Western Australia. School of Civil and Resource Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2008.0008.
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Three-dimensional scour propagation along offshore pipelines is a major reason to pipeline failures in an offshore environment. Although the research on scour in both numerical and experimental aspect has been extensive over the last three decades, the focus of the investigation has been limited to the two-dimensional aspect. The knowledge on three-dimensional scour is still limited. This dissertation presents the results of an experimental investigation on threedimensional scour along offshore pipelines in (1) steady currents (2) waves only and (3) combined waves and current. The major emphasis of the investigation is to investigate the propagation of the scour hole along the pipeline after the initiation of scour. Physical experiments conducted were used to quantify the effects of various parameters on scour propagation velocities along the pipeline. The problem of monitoring real time scour below a pipeline was solved by using specifically developed conductivity scour probes. Effects of various parameters such as pipeline embedment depth, incoming flow Shields parameter, Keuglegan- Carpenter (KC) number and flow incident angle to the pipeline on scour propagation velocities along the pipeline were investigated. The investigations clearly reveal that scour propagation velocities generally increase with the increase of flow but decrease with the increase of the pipeline embedment depth. A general predictive formula for scour propagation velocities is proposed and validated against the experimental results. There are still some common issues related to pipeline scour that is lacking in the literature to date. One of these issues is the effects of Reynolds number on two-dimensional scour beneath pipelines. A numerical approach was adopted to investigate the Reynolds-number dependence of two-dimensional scour beneath offshore pipelines in steady currents. A novel wall function is proposed in calculating the suspended sediment transport rate in the model. The effects of Reynolds number were investigated by simulating the same undisturbed Shields parameters in both model and prototype but with different values of Reynolds number in two separate calculations. The results revealed that scour depths for prototype pipelines are about 10~15% smaller than those for model pipelines. The normalized time scales was found to be approximately the same, and the simulated scour profiles for the model pipelines agree well with the experimental results from an independent study. The backfilling of pipeline trenches is also an important issue to the design and management of offshore pipelines. A numerical model is developed to simulate the self-burial of a pipeline trench. Morphological evolutions of a pipeline trench under steady-current or oscillatory-flow conditions are simulated with/without a pipeline inside the trench. The two-dimensional Reynolds-averaged continuity and Navier-Stokes equations with the standard k-e turbulence closure, as well as the sediment transport equations, are solved using finite difference method in a curvilinear coordinate system. Different time-marching schemes are employed for the morphological computation under unidirectional and oscillatory conditions. It is found that vortex motions within the trench play an important role in the trench development.
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Sproule, David Surveying & Spatial Information Systems Faculty of Engineering UNSW. "Prediction of offshore gravity from bathymetry." Awarded by:University of New South Wales. School of Surveying and Spatial Information Systems, 2005. http://handle.unsw.edu.au/1959.4/22481.
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The definition of the shape of the geoid is a fundamental objective of geodesy, since it allows for the conversion between orthometric and ellipsoidal height systems. The geoid can be computed from gravity values measured over the surface of the earth, and considerable effort continues to achieve a global coverage of gravity values. One technique that has been very successful in recent years in providing gravity coverage in areas which previously have been too difficult to access is airborne gravimetry. This technique has proved very useful in covering near offshore regions, for example. The coastal regions of Australia are recognised as locations where airborne gravimetry has the potential to fill in missing gravity data. A pilot survey using an airborne gravity meter was undertaken off the north east coast of Australia. In areas that remain unsurveyed it is sometimes useful to fill in the missing gravity data values with predicted gravity values. Previous research has examined the possibility of predicting gravity values from other observed quantities. The best success has been achieved by using the gravity effect calculated from bathymetric information. Often the corresponding isostatic compensation is computed, and the combined bathymetric-isostatic gravity effect is used. However, the type and extent of compensation that exists in any particular region mostly remains unknown. Theoretical considerations indicate that the short wavelength part of the gravity field may be adequately modelled by the gravity effect of the bathymetry alone, without reference to an assumed compensation mechanism. With this in mind, a prediction scheme has been developed which utilises the short wavelength gravity field information implied by the bathymetry, combined with the long wavelength gravity field information from existing observed gravity. This scheme allows the prediction of ???fill-in??? gravity values in areas with limited observed gravity. The prediction technique was used on a test set of data off the east coast of Greenland. The prediction technique was seen to outperform a simple interpolation of gravity values by approximately ten percent. Geoid computations performed with the predicted gravity values indicate that the prediction technique can provide significant improvements in computed geoids.
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Wisznia, Roman. "Condition Monitoring of Offshore Wind Turbines." Thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-118455.
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The growing interest around offshore wind power, providing at the same time better wind conditions and fewer visual or environmental impacts, has lead many energy suppliers to consider the installation of offshore wind farms. However, the marine environment makes the installation and maintenance of wind turbines much more complicated, raising the capital and operation costs to an undesirable level and preventing the fast progression of this technology worldwide. Availability of offshore wind turbines varies between 65 and 90% depending on location, whereas onshore turbines range between 95 and 98% in most cases. In 2009, the ETI launched a research project aiming to improve economical efficiency of offshore wind farms by increasing their availability and decreasing their maintenance costs (partly through replacing corrective maintenance by preventive maintenance). This project named “Inflow” involves the development of a condition monitoring system, a system designed to monitor the state of different wind turbine components, and to analyze this data in order to determine the wind turbines overall condition at any given time, as well as its potential system ailments This paper describes two different approaches to perform the condition monitoring of offshore wind farms, the first one involves thresholds-based analysis, while the other involves pattern recognition.
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Ghadimi, R. "Nonlinear dynamic analysis of offshore structures." Thesis, Cranfield University, 1986. http://hdl.handle.net/1826/3581.
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In this thesis consideration is given to a selection
of nonlinear dynamic problems in the field of offshore
engineering. Hydrodynamic loading on fixed horizontal and
vertical tubular members and the dynamic response of articulated
towers together with the distribution of shear force and
bending moment along the tower are investigated using various
wave theories. Effects of nonlinear convective acceleration
terms in the calculation of fluid inertia forces and moments
are examined and attention is given to integration of wave
forces up to the free surface for vertical members. Calculation
of fluid loading at the displaced position of the articulated
tower and any Mathieu type instabilities that may occur
have been considered. The dynamic analysis of a damaged
Single Anchor Leg Storage (SALS) system subject to loss
of buoyancy in the yoke chamber is studied. The equations
of motion of the yoke/riser system are derived assuming
large displacements and solved in the time domain. Time
histories of the response, variations of the riser tension,
velocities of riser top end and the time histories of pivot
reactions are given. Natural periods and mode shapes for
small displacements of the system are calculated. Two methods
of simulating random seas, both represented by a sum of
harmonic wave components, are used to simulate second order
low frequency (slow drift) force on a tanker in head seas
by Pinkster's time domain method. In one method the wave
amplitudes are generated randomly from a Rayleigh distribution
and in the other they are obtained deterministically via
the wave spectrum. Time histories of slow drift force and
response together with simulation results with various duration
lengths are presented and compared. Estimates of the extreme
vessel response and its relation to rms value are compared
with the result of a commonly used method of determining
peak/rms ratios. The results of these investigations highlight
the importance of accurately simulating nonlinear effects
in both fixed, floating and compliant offshore structures
from the point of view of safe design and operation of such-
systems.
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Ahmadi-Nedushan, Behrooz 1966. "Progressive collapse analysis of offshore platforms." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22639.
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This thesis presents a study of the ultimate strength capacity of two offshore platforms located in the Gulf of Mexico. The objective of the study was to validate existing non-linear finite element models for estimating the loads and strength of offshore platforms.<br>From August 24 to 26 1992, hurricane Andrew moved through the Gulf of Mexico with sustained winds of 140 miles per hour. Thirty-six major platforms suffered significant damage, of these, ten were completely toppled and twenty-six were leaning significantly or had significant topside damage.<br>Structures "H" and "K" were bridge-connected platforms, located in the ST151 field of the South Timbalier area of the Gulf of Mexico, platform "H" collapsed during Andrew, while "K" survived undamaged. They were both designed, fabricated, and installed in the early 1960's.<br>A push-over analysis, using the program USFOS was used to estimate the ultimate strength of the two structures in three direction: end-on, diagonal and broadside.<br>In the first series of analyses, all the primary members such as legs, vertical and horizontal braces, piles, soil, conductors and deck structure were precisely defined with appropriate finite elements as well as secondary members such as conductors guides barge bumpers. In the second series of analyses it was assumed that there was no horizontal or vertical movements at the level of the mudmat. In the third series of analysis the model used in the first series of analysis was modified by increasing stiffness and resistance of the piles 10 times. Finally a fourth model was investigated in which the soil resistance of the mud-level horizontal members is modelled. (Abstract shortened by UMI.)
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Thebault, Ludovic Pierre Julien. "Offshore financial centres and bank efficiency." Thesis, Bangor University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432781.
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Wilkinson, Michael Richard. "Condition Monitoring for Offshore Wind Turbines." Thesis, University of Newcastle Upon Tyne, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492117.
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O'Donnell, Ryan. "HVDC machines for offshore wind generation." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.498850.
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Roberts, Abigail Mary. "Workplace attitudes among offshore team members." Thesis, University of Canterbury. Psychology, 2014. http://hdl.handle.net/10092/9164.
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The attitudes of employees are key for ensuring the productivity and sustainability of an organisation. The present research aimed to explore obstacles and facilitators of positive team functioning in an offshore environment. Preliminary identification of obstacles and challenges to effective teamwork was achieved through an interview with two senior Human Resource managers at a large international bank, the primary location of which is in Australia. From this information, a survey was developed and distributed to members of an offshore Human Resource (HR) service centre consisting of 100 staff members, responsible for HR operations and described as an ‘extension’ or ‘captive’ team. An interview with management revealed that the effectiveness and sustainability of the current offshore team were of particular interest. Consideration of these issues and research into the effectiveness of virtual and captive teams led to a focus on organisational identity, work engagement, climate, trust, recognition from management, technology support, reliability of technology and goal clarity. Goal clarity and technology support were significant predictors of work engagement; low integration, goal clarity, technology support, reliability of technology and recognition from management were significant predictors of organisational identity. Thus, in an offshore environment, clear goals and the ability to complete those goals through use of efficient technologies are vital. This should impact the type of training given to offshore team members as well as the amount of technology support that is available to them.
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Athamna, Issam [Verfasser]. "Zuverlässigkeitsberechnung von Offshore-Windparks / Issam Athamna." Berlin : epubli GmbH, 2015. http://d-nb.info/1075096871/34.
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Skriver, Jan. "Emergency decision making on offshore installations." Thesis, University of Aberdeen, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265383.
Texto completoResumen
The aim of this thesis was to examine the cognitive processes through which experienced Offshore Installation Managers (OIMs) make decisions during emergencies, and to determine whether they use a naturalistic or normative decision making strategy. That is, do they recognise the emergency as familiar and base decisions on condition-action rules serially generated (naturalistic), or do they need to concurrently compare and contrast options before selecting the best possible (normative). Emphasis was on the individual OIM's understanding of an emergency and the meaning he attached to the information or events taking place. The method employed to achieve this objective, was a Cognitive Task Analysis (CTA) based on triangulation principles, i.e. using multiple methods to examine the same research question and so enhance reliability and validity. The main findings of this thesis were: • Decision making in Safety Case (1992) identified offshore installation emergencies is primarily based on condition-action rules, or rule-based according to Rasmussen's (1983) model, not Standard Operating Procedures. • Decisions are serially generated. There is no evidence of option comparison. • The environment severely limits the number of options available to the OIM. • Decisions are predominantly made when one element of the present status of the incident changes. • Tactical decisions account for approximately 54% and operational decisions for 46% of the decisions made. • Nearly 50% of the decisions taken are instigated by other team members. • The majority of the time (86.8%) is spent on situation assessment. • The OIMs' situation awareness is limited to a maximum of eight interdependent problem categories. • Situation awareness comprises approximately four categories at any one point. • Risk and time pressure are the two major factors contributing to incident assessment. • There are individual differences in decision making style and situation awareness.
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Storey, Malcolm R. "Innovations in offshore supply chain relationships." Thesis, University of Newcastle Upon Tyne, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413024.
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Rodriguez-Sanchez, Jose Efrain. "Fatigue crack repair for offshore structures." Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313721.
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Trim, A. D. "Probabilistic dynamic analysis of offshore structures." Thesis, Cranfield University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376215.
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