Cyclic Behaviour of Laterally Loaded Monopiles in Sand Supporting Offshore Wind Turbines

DEFF Research Database (Denmark)

Nicolai, Giulio

2018-01-01

Almost 90% of the current offshore wind turbines are supported by monopiles, which are steel hollow piles with a large diameter. Nevertheless, monopiles are currently designed with inappropriate methods that were developed by the oil and gas industry for slender piles that are different from...

A GLANCE AT OFFSHORE WIND TURBINE FOUNDATION STRUCTURES

Directory of Open Access Journals (Sweden)

Jianhua Zhang

2016-06-01

Full Text Available Energy poverty and climate change are crucial issues we face in our societies. Offshore wind energy has been a reliable solution to both of these problems - solving our growing energy problems while reducing CO2 emission. Innovative foundation design is one of the setbacks faced by this industry. Designing and constructing a cost effective offshore wind farm is greatly hampered by technical and infrastructural challenges, especially in foundation structures. This paper provides a detailed overview of issues related to this problem, with the aim of eliminating the frequent misunderstandings which can arise among engineers and investors working in the offshore wind energy sector. It begins by investigating the latest data and recommendations regarding the design and deployment of various kinds of offshore wind turbine (OWT foundations. It provides a framework which enables us to study the different OWT foundations, including prototypes and their limitations. Various structural failure modes are highlighted and corrosion measures are presented. Moreover, various removal methods of support structures are put forward. Finally, this paper presents the setbacks preventing the spread of offshore wind energy and the future works for offshore wind energy applications.

Offshore concrete structures; Estructuras Offshore (mar adentro) de Hormigon

Energy Technology Data Exchange (ETDEWEB)

Lamas Pardo, M.; Carral Couce, L. M.

2011-07-01

In the offshore industry there are two possible materials for the construction of the hull of a structure; the steel and concrete, with the first one widely used until now, as in the rest of the shipbuilding industry of merchant ships, warships, etc. Materials such as aluminum, GRP or timber areused in small units with lengths lower than 100 m, and in less adverse conditions than in the offshore industry. Nevertheless, some ships/barges have been built of concrete in the past, but have been rather isolated cases which have not changed the practice in the industry. In the First and Second World War were built by the scarcity of materials, while the series of barges by Alfred A. Yee was a rare exception. Other units were also made in concrete, but almost anecdotal. Still, the behaviour of these concrete structures, especially in terms of maintenance, has been excellent. Therefore, the fact that the concrete has not had an adequate reception so far in shipbuilding, does not mean that in will not be the material best suited for the offshore industry in the future. The extra displacement and associated fuel costs in concrete ships have been found prohibitive in the past. But the loss of mobility of a concrete hull in relation to a steel hull can be perfectly offset by the advantages offered by the concrete, as the shipping and offshore industry have very different priorities. One of the main differences in these priorities is in terms of maintenance and resistance to fatigue, precisely where the concrete performs better. ships can easily be dry docked for maintenance and repair, while in the offshore platforms these works have to be done in situ so maintenance and fatigue are crucial to them. Besides these, the concrete has other advantages according to findings of several studies. And although they are interested in the conclusions that the makes as they came from people in the concrete industry, the fact that in recent years concrete offshore unit shave been built

Human and organization factors: engineering operating safety into offshore structures

International Nuclear Information System (INIS)

Bea, Robert G.

1998-01-01

History indicates clearly that the safety of offshore structures is determined primarily by the humans and organizations responsible for these structures during their design, construction, operation, maintenance, and decommissioning. If the safety of offshore structures is to be preserved and improved, then attention of engineers should focus on to how to improve the reliability of the offshore structure 'system,' including the people that come into contact with the structure during its life-cycle. This article reviews and discusss concepts and engineering approaches that can be used in such efforts. Two specific human factor issues are addressed: (1) real-time management of safety during operations, and (2) development of a Safety Management Assessment System to help improve the safety of offshore structures

Risk assessment for ship collisions against offshore structures

DEFF Research Database (Denmark)

Pedersen, Preben Terndrup

2014-01-01

to changes in ship traffic in the vicinity of the offshore structures and new developments within navigational equipment and pro¬cedures. The paper highlights some of the available analytical elements in collision frequency estimation and response calculations for different types of offshore installations......Offshore installations served by in-field vessels and/or situated in the vicinity of ship traf¬fic lanes are exposed to collision hazards such as risk of loss of life, economic loss, and environmental damage. Therefore, one of the many performance goals in the design phase of such structures...... and indicates how these tools can be applied to evaluate relevant risk control options....

Strengthening, modification and repair techniques’ prioritization for structural integrity control of ageing offshore structures

International Nuclear Information System (INIS)

Samarakoon, Samindi M.K.; Ratnayake, R.M. Chandima

2015-01-01

Structural integrity control is vital for existing ageing as well as newly built offshore and onshore structures. Structural integrity control becomes highly sensitive to interventions under a potential loss of structural integrity when it comes to offshore oil and gas production and process facilities. This is mainly due to the inherent constraints present in carrying out engineering work in the offshore atmosphere. It has been further exacerbated by the ageing offshore structures and the necessity of carrying out life extension toward the end of their design service lives. Local and international regulations demand the implementation of appropriate strengthening, modification and repair plans when significant changes in the structural integrity are revealed. In this context, strengthening, modification and repair techniques such as welding, member removal/reduction of loading, mechanical clamping and grouted repairs play a vital role. This manuscript presents an approach for prioritizing the strengthening, modification and repair techniques using a multi-criteria analysis approach. An analytic hierarchy process has been selected for the analysis via an illustrative case. It also provides a comprehensive overview of currently existing; strengthening, modification and repair techniques and their comparative pros and cons. - Highlights: • Structural integrity control (SIC) of ageing and intact offshore structures. • Strengthening, modification and/or repair (SMR) techniques have been explained. • Application of multi-criteria analysis conserving SI has been illustrated. • SMR techniques prioritization and sensitivity analysis has been performed

The International Standards Organisation offshore structures standard

International Nuclear Information System (INIS)

Snell, R.O.

1994-01-01

The International Standards Organisation has initiated a program to develop a suite of ISO Codes and Standards for the Oil Industry. The Offshore Structures Standard is one of seven topics being addressed. The scope of the standard will encompass fixed steel and concrete structures, floating structures, Arctic structures and the site specific assessment of mobile drilling and accommodation units. The standard will use as base documents the existing recommended practices and standards most frequently used for each type of structure, and will develop them to incorporate best published and recognized practice and knowledge where it provides a significant improvement on the base document. Work on the Code has commenced under the direction of an internationally constituted sub-committee comprising representatives from most of the countries with a substantial offshore oil and gas industry. This paper outlines the background to the code and the format, content and work program

The offshore trend: Structural changes in the wind power sector

International Nuclear Information System (INIS)

Markard, Jochen; Petersen, Regula

2009-01-01

In recent years, the wind power sector has begun to move offshore, i.e. to use space and good wind speeds on the open sea for large scale electricity generation. Offshore wind power, however, is not just technologically challenging but also a capital intensive and risky business that requires particular financial and organizational resources not all potential investors might have. We therefore address the question, what impact offshore wind power may have on ownership and organizational structures in the wind power sector. We compare on- and offshore wind park ownership in Denmark, the UK and Germany. The analysis shows that offshore wind power in all three countries is dominated by large firms, many of which are from the electricity sector. In Denmark and the UK, also investors from the gas and oil industry play an important role in the offshore wind business. This development represents a major shift for countries such as Germany and Denmark, in which the wind power sector has grown and matured on the basis of investments by individuals, farmers, cooperatives and independent project developers. The structural changes by which offshore wind power is accompanied have consequences for turbine manufacturers, project developers, investors, associations and policy makers in the field.

Stochastic Analysis of Offshore Steel Structures An Analytical Appraisal

CERN Document Server

Karadeniz, Halil

2013-01-01

Stochastic Analysis of Offshore Steel Structures provides a clear and detailed guide to advanced analysis methods of fixed offshore steel structures using 3D beam finite elements under random wave and earthquake loadings. Advanced and up-to-date research results are coupled with modern analysis methods and essential theoretical information to consider optimal solutions to structural issues. As these methods require and use knowledge of different subject matters, a general introduction to the key areas is provided. This is followed by in-depth explanations supported by design examples, relevant calculations and supplementary material containing related computer programmers. By combining this theoretical and practical approach Stochastic Analysis of Offshore Steel Structures cover a range of key concepts in detail including: ·         The basic principles of standard 3D beam finite elements and special connections, ·         Wave loading - from hydrodynamics to the calculation of wave load...

Fluid Damping Variation of a Slender Rod in Axial Flow Field

Energy Technology Data Exchange (ETDEWEB)

Park, Nam-Gyu; Yoo, Jong-Sung; Jung, Yil-Sup [KEPCO Nuclear Fuel Co., Daejeon (Korea, Republic of)

2016-10-15

This study proposed an analytic damping model considering the axial flow condition. In addition, the specific damping values with respect to the flow speeds are calculated. The flow induced damping is beneficial to fuel integrity in that impact energy due to severe accidents such as earthquake dissipates rapidly. A nuclear fuel bundle is composed of many slender fuel rods which contain fission material. The slender rod is typical structure in the fuel, therefore fluid damping estimation on the rod should be an important clue leading to fuel bundle damping identification. Severe accidents could cause fuel assembly vibration in the core, but large motion could be damped out rapidly when a strong damping mechanism is involved. This paper suggested a mathematical model of the slender structure. The physical meaning of the model is described, and the simulation results with the model are also provided. Actual damping due to the fluid is nonlinear, therefore further works are required to explain the detail behavior with the nonlinearity. The model validation test is on-going in KEPCO Nuclear Fuel, but it is believed that performance of the model is well correlated to the published work.

Experimental study on moonpool resonance of offshore floating structure

Directory of Open Access Journals (Sweden)

Seung-Ho Yang

2013-06-01

Full Text Available Offshore floating structures have so-called moonpool in the centre area for the purpose of drilling, installation of subsea structures, recovery of Remotely-Operated Vehicle (ROV and divers. However, this vertical opening has an effect on the operating performance of floating offshore structure in the vicinity of moonpool resonance frequency; piston mode and sloshing mode. Experimental study based on model test was carried out. Moonpool resonance of floating offshore structure on fixed condition and motion free condition were investigated. And, the effect of cofferdam which is representative inner structure inside moonpool was examined. Model test results showed that Molin's theoretical formula can predict moonpool resonance on fixed condition quite accurately. However, motion free condition has higher resonance frequency when it is compared with that of motion fixed. The installation of cofferdam moves resonance frequency to higher region and also generates secondary resonance at lower frequency. Furthermore, it was found that cofferdam was the cause of generating waves in the longitudinal direction when the vessel was in beam sea.

Hybrid Method Simulation of Slender Marine Structures

DEFF Research Database (Denmark)

Christiansen, Niels Hørbye

This present thesis consists of an extended summary and five appended papers concerning various aspects of the implementation of a hybrid method which combines classical simulation methods and artificial neural networks. The thesis covers three main topics. Common for all these topics...... only recognize patterns similar to those comprised in the data used to train the network. Fatigue life evaluation of marine structures often considers simulations of more than a hundred different sea states. Hence, in order for this method to be useful, the training data must be arranged so...... that a single neural network can cover all relevant sea states. The applicability and performance of the present hybrid method is demonstrated on a numerical model of a mooring line attached to a floating offshore platform. The second part of the thesis demonstrates how sequential neural networks can be used...

Probabilistic Calibration of Fatigue Design Factors for Offshore Wind Turbine Support Structures

DEFF Research Database (Denmark)

Ramirez, José Rangel; Sørensen, John Dalsgaard

2010-01-01

for the considered offshore wind turbines in such a way that the specific uncertainties for the fatigue life are accounted in a rational manner. Similar approaches have been used for offshore oil & gas sub-structures, but the required reliability level for offshore wind turbines is generally lower and the fatigue......This paper describes a reliability-based approach to determine fatigue design factors (FDF) for offshore wind turbine support structures made of steel. The FDF values are calibrated to a specific reliability level and linked to a specific inspection and maintenance (I&M) strategy used...

CARIBBEAN OFFSHORE CORPORATE STRUCTURES UNDER A SWOT ANALYSIS

Directory of Open Access Journals (Sweden)

Ana-Maria GEAMÃNU

2015-04-01

Full Text Available Tax havens have long been under the attention of numerous Governments and International Organizations which triggered the concern of an uneven playing field in the taxation area. As a result numerous amendments have been made to both their commercial and tax legislations in order to be in line with the internationally agreed tax standards. The aim of this article is to conduct a SWOT analysis on the offshore corporate structures found in the Caribbean landscape. Based on a selection process of the most commonly recognized tax havens in the Caribbean region and an analysis of their offshore companies at the level of incorporation, administration, activities conducted and costs, a set of frequently met characteristics have been identified which stand at the basis of the SWOT analysis. The results stand to present a comprehensive four dimension framework of the offshore corporate structures in regards to their strengths, weaknesses, opportunities and threats.

Reliability analysis of an offshore structure

DEFF Research Database (Denmark)

Sorensen, J. D.; Faber, M. H.; Thoft-Christensen, P.

1992-01-01

A jacket type offshore structure from the North Sea is considered. The time variant reliability is estimated for failure defined as brittle fracture and crack through the tubular member walls. The stochastic modelling is described. The hot spot stress spectral moments as function of the stochasti...

Damage Detection in an Offshore Structure

DEFF Research Database (Denmark)

Brincker, Rune; Kirkegaard, Poul Henning; Andersen, P.

The structural integrity of a multi-pile offshore platform is investigated by using a vibration based damage detection scheme. Changes in structural integrity are assumed to be reflected in the modal parameters estimated from only output data using an Auto-Regressive Moving Average (ARMA) model....... By use of the estimates of the modal parameters and their corresponding variances a probability based damage indicator is formulated. This approach indicates, that since the construction of the platform, minor structural changes have taken place....

Damage Detection in an Offshore Structure

DEFF Research Database (Denmark)

Brincker, Rune; Kirkegaard, Poul Henning; Andersen, Palle

1995-01-01

The structural integrity of a multi-pile offshore platform is investigated by using a vibration based damage detection scheme. Changes in structural integrity are assumed to be reflected in the modal parameters estimated from only output data using an Auto-Regressive Moving Average (ARMA) model....... By use of the estimates of the modal parameters and their corresponding variances a probability based damage indicator is formulated. This approach indicates, that since the construction of the platform, minor structural changes have taken place....

Steel Plate Shear Walls: Efficient Structural Solution for Slender High-Rise in China

International Nuclear Information System (INIS)

Mathias, Neville; Long, Eric; Sarkisian, Mark; Huang Zhihui

2008-01-01

The 329.6 meter tall 74-story Jinta Tower in Tianjin, China, is expected, when complete, to be the tallest building in the world with slender steel plate shear walls used as the primary lateral load resisting system. The tower has an overall aspect ratio close to 1:8, and the main design challenge was to develop an efficient lateral system capable of resisting significant wind and seismic lateral loads, while simultaneously keeping wind induced oscillations under acceptable perception limits. This paper describes the process of selection of steel plate shear walls as the structural system, and presents the design philosophy, criteria and procedures that were arrived at by integrating the relevant requirements and recommendations of US and Chinese codes and standards, and current on-going research

Loads for use in the design of ships and offshore structures

DEFF Research Database (Denmark)

Hirdaris, S.E.; Bai, W.; Dessi, Daniele

2014-01-01

The evaluation of structural responses is key element in the design of ships and offshore structures. Fundamental to this is the determination of the design loads to support the Rule requirements and for application in direct calculations. To date, the current design philosophy for the prediction...... of motions and wave-induced loads has been driven by empirical or first-principles calculation procedures based on well-proven applications such as ship motion prediction programs. In recent years, the software, engineering and computer technology available to predict the design loads imposed on ships...... and offshore structures has improved dramatically. Notwithstanding, with the stepwise increase in the size and structural complexity of ships and floating offshore installations and the advances in the framework of Rules and Standards it has become necessary to utilise the latest technologies to assess...

Optimal Structural Reliability of Offshore Wind Turbines

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard; Tarp-Johansen, N.J.

2005-01-01

The main failure modes of modern large wind turbines are fatigue failure of wings, hub, shaft and main tower, local buckling of main tower, and failure of the foundation. This paper considers reliability-based optimal design of wind turbines. Compared to onshore wind turbines and building...... structures, humans spent little time in the vicinity of offshore wind turbines and the probability of human injury during storm conditions is small. Further environmental pollution will also in general be small in case of failure. One could therefore argue that the reliability level of offshore wind turbines...... can be lower than for onshore wind turbines and other civil engineering structures and can be assessed by reliability-based cost-optimization. Specifically this paper considers the main tower and foundation. Both fatigue and ultimate strength failure modes are included. Different formulations...

Integrated Multidisciplinary Constrained Optimization of Offshore Support Structures

International Nuclear Information System (INIS)

Haghi, Rad; Molenaar, David P; Ashuri, Turaj; Van der Valk, Paul L C

2014-01-01

In the current offshore wind turbine support structure design method, the tower and foundation, which form the support structure are designed separately by the turbine and foundation designer. This method yields a suboptimal design and it results in a heavy, overdesigned and expensive support structure. This paper presents an integrated multidisciplinary approach to design the tower and foundation simultaneously. Aerodynamics, hydrodynamics, structure and soil mechanics are the modeled disciplines to capture the full dynamic behavior of the foundation and tower under different environmental conditions. The objective function to be minimized is the mass of the support structure. The model includes various design constraints: local and global buckling, modal frequencies, and fatigue damage along different stations of the structure. To show the usefulness of the method, an existing SWT-3.6-107 offshore wind turbine where its tower and foundation are designed separately is used as a case study. The result of the integrated multidisciplinary design optimization shows 12.1% reduction in the mass of the support structure, while satisfying all the design constraints

Slipping slender bodies and enhanced flagellar locomotion

Science.gov (United States)

Man, Yi; Lauga, Eric

2017-11-01

In the biological world, many cells exploit slender appendages to swim, include numerous species of bacteria, algae and spermatozoa. A classical method to describe the flow field around such appendages is slender-body theory (SBT), which is often used to study flagellar motility in Newtonian fluids. However, biology environments are often rheologically complex due to the presence of polymers. These polymers generically phase-separate near rigid boundaries where low-viscosity fluid layers lead to effective slip on the surface. In this talk, we present an analytical derivation of SBT in the case where the no-slip boundary condition on the appendage is replaced by a Navier slip boundary condition. Our results demonstrate in particular a systematic reduction of the resistance coefficient of the slender filaments in their tangential direction, which leads to enhanced flagellar locomotion.

Offshore code comparison collaboration continuation (OC4), phase I - Results of coupled simulations of an offshore wind turbine with jacket support structure

DEFF Research Database (Denmark)

Popko, Wojciech; Vorpahl, Fabian; Zuga, Adam

2012-01-01

In this paper, the exemplary results of the IEA Wind Task 30 "Offshore Code Comparison Collaboration Continuation" (OC4) Project - Phase I, focused on the coupled simulation of an offshore wind turbine (OWT) with a jacket support structure, are presented. The focus of this task has been the verif......In this paper, the exemplary results of the IEA Wind Task 30 "Offshore Code Comparison Collaboration Continuation" (OC4) Project - Phase I, focused on the coupled simulation of an offshore wind turbine (OWT) with a jacket support structure, are presented. The focus of this task has been...... the verification of OWT modeling codes through code-to-code comparisons. The discrepancies between the results are shown and the sources of the differences are discussed. The importance of the local dynamics of the structure is depicted in the simulation results. Furthermore, attention is given to aspects...

Stochastic Fatigue Analysis of Jacket Type Offshore Structures

DEFF Research Database (Denmark)

Sigurdsson, Gudfinnur

In this paper, a stochastic reliability assessment for jacket type offshore structures subjected to wave loads in deep water environments is outlined. In the reliability assessment, structural and loading uncertainties are taken into account by means of some stochastic variables. To estimate stat...... statistical measures of structural stress variations the modal spectral analysis method is applied....

FIVE REGIONAL PERSPECTIVES OF CONSTRUCTING AN OFFSHORE CORPORATE STRUCTURE

Directory of Open Access Journals (Sweden)

Ana-Maria GEAMÃNU

2015-04-01

Full Text Available The offshore company, the emblem of the tax haven jurisdictions, is owned by non-residents and it conducts activities outside the island of incorporation in order to benefit from tax advantages. The purpose of this paper is to conduct a comparative analysis on the trends of constructing the offshore corporate structures at the level of five regions where tax havens have been identified: The Caribbean Sea and Central America; Europe; Asia; The Indian Ocean and The Pacific Ocean. Based on the tax and corporate legislations the analysis is focused on the main tax advantages offered by these entities, the incorporation and administration procedures as well as the costs involved. The results have shown that pure offshore corporate legislation is to be found at the level of only three geographic areas: The Caribbean Sea and Central America; The Indian Ocean and The Pacific Ocean and the offshore law is predominantly international, with only fine regional differences.

Theory of timber connections with slender dowel type fasteners

DEFF Research Database (Denmark)

Svensson, Staffan; Munch-Andersen, Jørgen

2018-01-01

A theory on the lateral load-carrying capacity of timber connections with slender fasteners is presented. The base of the theory is the coupled mechanical phenomena acting in the connection, while the wood and the slender fastener deform and yield prior to failure. The objective is to derive...... a sufficient description of actions and responses which have determining influence on the load-carrying capacity of timber connections with slender fasteners. Model assumptions are discussed and made, but simplifications are left out. Even so, simple mathematical equations describing the lateral capacity......-carrying capacity of the tested connections....

SOFIA - A simulation tool for bottom founded and floating offshore structures

DEFF Research Database (Denmark)

Nielsen, Morten Eggert; Ulriksen, Martin Dalgaard; Damkilde, Lars

2017-01-01

This paper presents a recently developed simulation tool, SOFIA (Simulation Of Floaters In Action), suitable for modeling slender bottom founded and moored/freely floating space frame structures exposed to environmental loads. In contrast to traditional rigid body formulations of floating...... and structure domains, which are coupled through the structural equation of motion. The structural domain is handled by means of the finite element method, while large displacements and stress stiffening effects, exhibited by moored floating structures, are inherently included due to a co-rotational element...... formulation. The fluid domain is modeled by an appropriate water wave theory, and the hydrodynamic loads are evaluated at the instantaneous fluid-structure interface by means of a relative Morison equation. The equation of motion is solved in time domain, which makes SOFIA capable of handling bottom founded...

Value of information-based inspection planning for offshore structures

DEFF Research Database (Denmark)

Irman, Arifian Agusta; Thöns, Sebastian; Leira, Bernt J.

2017-01-01

with each inspection strategy. A simplified and generic risk-based inspection planning utilizing pre- posterior Bayesian decision analysis had been proposed by Faber et al. [1] and Straub [2]. This paper provides considerations on the theoretical background and a Value of Information analysis......-based inspection planning. The paper will start out with a review of the state-of-art RBI planning procedure based on Bayesian decision theory and its application in offshore structure integrity management. An example of the Value of Information approach is illustrated and it is pointed to further research......Asset integrity and management is an important part of the oil and gas industry especially for existing offshore structures. With declining oil price, the production rate is an important factor to be maintained that makes integrity of the structures one of the main concerns. Reliability based...

Stress state reassessment of Romanian offshore structures taking into account corrosion influence

Science.gov (United States)

Joavină, R.; Zăgan, S.; Zăgan, R.; Popa, M.

2017-08-01

Progressive degradation analysis for extraction or exploration offshore structure, with appraisal of failure potential and the causes that can be correlated with the service age, depends on the various sources of uncertainty that require particular attention in design, construction and exploitation phases. Romanian self erecting platforms are spatial lattice structures consist of tubular steel joints, forming a continuous system with an infinite number of dynamic degrees of freedom. Reassessment of a structure at fixed intervals of time, recorrelation of initial design elements with the actual situation encountered in location and with structural behaviour represents a major asset in lowering vulnerabilities of offshore structure. This paper proposes a comparative reassessment of the stress state for an offshore structure Gloria type, when leaving the shipyard and at the end of that interval corresponding to capital revision, taking into account sectional changes due to marine environment corrosion. The calculation was done using Newmark integration method on a 3D model, asses of the dynamic loads was made through probabilistic spectral method.

Benefits of Risk Based Inspection Planning for Offshore Structures

DEFF Research Database (Denmark)

Straub, D.M.; Goyet, J.; Sørensen, John Dalsgaard

2006-01-01

The economical benefits of applying risk-based inspection planning (RBI) for offshore structures subject to fatigue are evaluated based on experiences from past industrial projects. To this end, the factors influencing the cost of inspection, repair and failure of structures are discussed......, the financial benefit of RBI is assessed....

Probabilistic Design of Offshore Structural Systems

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard

1988-01-01

Probabilistic design of structural systems is considered in this paper. The reliability is estimated using first-order reliability methods (FORM). The design problem is formulated as the optimization problem to minimize a given cost function such that the reliability of the single elements...... satisfies given requirements or such that the systems reliability satisfies a given requirement. Based on a sensitivity analysis optimization procedures to solve the optimization problems are presented. Two of these procedures solve the system reliability-based optimization problem sequentially using quasi......-analytical derivatives. Finally an example of probabilistic design of an offshore structure is considered....

Probabilistic Design of Offshore Structural Systems

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard

Probabilistic design of structural systems is considered in this paper. The reliability is estimated using first-order reliability methods (FORM). The design problem is formulated as the optimization problem to minimize a given cost function such that the reliability of the single elements...... satisfies given requirements or such that the systems reliability satisfies a given requirement. Based on a sensitivity analysis optimization procedures to solve the optimization problems are presented. Two of these procedures solve the system reliability-based optimization problem sequentially using quasi......-analytical derivatives. Finally an example of probabilistic design of an offshore structure is considered....

Applicability of WaveWatch-III wave model to fatigue assessment of offshore floating structures

NARCIS (Netherlands)

Zou, T.; Kaminski, M.L.

2016-01-01

In design and operation of floating offshore structures, one has to avoid fatigue failures caused by action of ocean waves. The aim of this paper is to investigate the applicability of WaveWatch-III wave model to fatigue assessment of offshore floating structures. The applicability was investigated

Wave kinematics and response of slender offshore structures. Vol 4: Wave kinematics

Energy Technology Data Exchange (ETDEWEB)

Riber, H.J.

1999-08-01

The kinematics of large surface waves has been measured by means of sonar's placed on the sea floor at the Tyra field. Measurements from the most severe storm are analysed and extreme wave velocity profiles are compared to Stoke wave velocity profiles. Statistical distributions of crest velocity and wave celerity are presented. The analysis shows how the deviation from the Stokes prediction varies with wave heights and steepness. Analyses of the directional wave field leads to the conclusion that the extreme waves are three-dimensional. It is shown that the peculiar kinematics of extreme waves is of great relevance to the design of jacket type structures. (au)

An investigation on fatigue in high-strength steel offshore structures

DEFF Research Database (Denmark)

Agerskov, Henning; Petersen, R.I.; Martinez, L. Lopez

1998-01-01

of the investigation, fatigue test series were carried out on both full scale tubular joints and smaller welded plate test specimens in high-strength steel as well as in conventional offshore structural steel. This paper gives a summary of the main results presented in two recent research reports [15, 16], from...... these investigations. A comparison between constant amplitude and variable amplitude fatigue test results shows shorter fatigue lives in variable amplitude loading than should be expected from the linear fatigue damage accumulation formula.Furthermore, in general longer fatigue lives were obtained for the test...... specimens in high-strength steel than those obtained in corresponding tests on joints in conventional offshore structural steel....

Review of laterally loaded monopiles employed as the foundation for offshore wind turbines

Energy Technology Data Exchange (ETDEWEB)

Hyldal Soerensen, S.P.; Thoustrup Broedbaek, K.; Moeller, Martin; Hust Augustesen, A.

2012-03-15

The monopiles foundation concept is often employed as the foundation for offshore wind turbine converters. These piles are highly subjected to lateral loads and overturning moments due to wind and wave forces. Typically monopiles with diameters of 4 to 6 m and embedded pile lengths of 15 to 30 m are necessary. In current practice these piles are normally designed by use of the p-y curve method although the method is developed and verified for small-diameter, slender piles. In the present paper a review of the existing p-y curve formulations for piles in sand is presented. Based on numerical and experimental studies presented in the literature, advances and limitations of the current p-y curve formulations are outlined. The review focuses on the design of monopile foundations for offshore wind turbine converters. (Author)

An Investigation on Fatigue in High-Strength Steel Offshore Structures

DEFF Research Database (Denmark)

Agerskov, Henning; Petersen, R.I.; Lopez Martinez, L.

1997-01-01

. In the experimental part of the investigation, fatigue test series have been carried through on both full-scale tubular joints and smaller welded plate test specimens, in high-strength steel as well as in conventional offshore structural steel. The present document gives a summary of the main results presented in two...... recent research reports, Refs. 15 and 16, from these investigations.A comparison between constant amplitude and variable amplitude fatigue test results shows shorter fatigue lives in variable amplitude loading than should be expected from the linear fatigue damage accumulation formula. Furthermore......, in general longer fatigue lives were obtained for the test specimens in high-strength steel than those obtained in corresponding tests on joints in conventional offshore structural steel....

Dynamic analysis of a 5-MW tripod offshore wind turbine by considering fluid-structure interaction

Science.gov (United States)

Zhang, Li-wei; Li, Xin

2017-10-01

Fixed offshore wind turbines usually have large underwater supporting structures. The fluid influences the dynamic characteristics of the structure system. The dynamic model of a 5-MW tripod offshore wind turbine considering the pile-soil system and fluid structure interaction (FSI) is established, and the structural modes in air and in water are obtained by use of ANSYS. By comparing low-order natural frequencies and mode shapes, the influence of sea water on the free vibration characteristics of offshore wind turbine is analyzed. On basis of the above work, seismic responses under excitation by El-Centro waves are calculated by the time-history analysis method. The results reveal that the dynamic responses such as the lateral displacement of the foundation and the section bending moment of the tubular piles increase substantially under the influence of the added-mass and hydrodynamic pressure of sea water. The method and conclusions presented in this paper can provide a theoretical reference for structure design and analysis of offshore wind turbines fixed in deep seawater.

Design and validation of a slender guideway for Maglev vehicle by simulation and experiment

Science.gov (United States)

Han, Jong-Boo; Han, Hyung-Suk; Kim, Sung-Soo; Yang, Seok-Jo; Kim, Ki-Jung

2016-03-01

Normally, Maglev (magnetic levitation) vehicles run on elevated guideways. The elevated guideway must satisfy various load conditions of the vehicle, and has to be designed to ensure ride quality, while ensuring that the levitation stability of the vehicle is not affected by the deflection of the guideway. However, because the elevated guideways of Maglev vehicles in South Korea and other countries fabricated so far have been based on over-conservative design criteria, the size of the structures has increased. Further, from the cost perspective, they are unfavourable when compared with other light rail transits such as monorail, rubber wheel, and steel wheel automatic guided transit. Therefore, a slender guideway that does have an adverse effect on the levitation stability of the vehicle is required through optimisation of design criteria. In this study, to predict the effect of various design parameters of the guideway on the dynamic behaviour of the vehicle, simulations were carried out using a dynamics model similar to the actual vehicle and guideway, and a limiting value of deflection ratio of the slender guideway to ensure levitation control is proposed. A guideway that meets the requirement as per the proposed limit for deflection ratio was designed and fabricated, and through a driving test of the vehicle, the validity of the slender guideway was verified. From the results, it was confirmed that although some increase in airgap and cabin acceleration was observed with the proposed slender guideway when compared with the conventional guideway, there was no notable adverse effect on the levitation stability and ride quality of the vehicle. Therefore, it can be inferred that the results of this study will become the basis for establishing design criteria for slender guideways of Maglev vehicles in future.

A Survey of Factors Affecting Blunt Leading-Edge Separation for Swept and Semi-Slender Wings

Science.gov (United States)

Luckring, James M.

2010-01-01

A survey is presented of factors affecting blunt leading-edge separation for swept and semi-slender wings. This class of separation often results in the onset and progression of separation-induced vortical flow over a slender or semi-slender wing. The term semi-slender is used to distinguish wings with moderate sweeps and aspect ratios from the more traditional highly-swept, low-aspect-ratio slender wing. Emphasis is divided between a selection of results obtained through literature survey a section of results from some recent research projects primarily being coordinated through NATO s Research and Technology Organization (RTO). An aircraft context to these studies is included.

Statistical Evaluation of the Identified Structural Parameters of an idling Offshore Wind Turbine

International Nuclear Information System (INIS)

Kramers, Hendrik C.; Van der Valk, Paul L.C.; Van Wingerden, Jan-Willem

2016-01-01

With the increased need for renewable energy, new offshore wind farms are being developed at an unprecedented scale. However, as the costs of offshore wind energy are still too high, design optimization and new innovations are required for lowering its cost. The design of modern day offshore wind turbines relies on numerical models for estimating ultimate and fatigue loads of the turbines. The dynamic behavior and the resulting structural loading of the turbines is determined for a large part by its structural properties, such as the natural frequencies and damping ratios. Hence, it is important to obtain accurate estimates of these modal properties. For this purpose stochastic subspace identification (SSI), in combination with clustering and statistical evaluation methods, is used to obtain the variance of the identified modal properties of an installed 3.6MW offshore wind turbine in idling conditions. It is found that one is able to obtain confidence intervals for the means of eigenfrequencies and damping ratios of the fore-aft and side-side modes of the wind turbine. (paper)

Offshore wind energy developments

DEFF Research Database (Denmark)

Stolpe, Mathias; Buhl, Thomas; Sumer, B. Mutlu

2014-01-01

This chapter will give a brief overview of a few of the activities within offshore wind energy research, specifically 1) Support structure optimization, 2) Blade coatings for wind turbines; 3) Scour protection of foundations, 4) Offshore HVDC and 5) Offshore wind services....

Offshore risk assessment

CERN Document Server

Vinnem, Jan-Erik

2014-01-01

  Offshore Risk Assessment was the first book to deal with quantified risk assessment (QRA) as applied specifically to offshore installations and operations. Risk assessment techniques have been used for more than three decades in the offshore oil and gas industry, and their use is set to expand increasingly as the industry moves into new areas and faces new challenges in older regions.   This updated and expanded third edition has been informed by a major R&D program on offshore risk assessment in Norway and summarizes research from 2006 to the present day. Rooted with a thorough discussion of risk metrics and risk analysis methodology,  subsequent chapters are devoted to analytical approaches to escalation, escape, evacuation and rescue analysis of safety and emergency systems.   Separate chapters analyze the main hazards of offshore structures: fire, explosion, collision, and falling objects as well as structural and marine hazards. Risk mitigation and control are discussed, as well as an illustrat...

Stress analysis of partial sphere used for bottom shell of off-shore structure

International Nuclear Information System (INIS)

Nishimaki, Ko; Matsumoto, Kohei; Hori, Tohru; Takeshita, Haruyuki; Iwata, Setsuo

1976-01-01

In the near future, various huge off-shore structures will be constructed. Concrete shall become a leading material in the structures, owing to its versatile properties. One of the limitations of concrete is its low tensile strength. The problem of low tensile strength of concrete is dealt with in main by two different methods: by applying prestressing and by designing the structural configuration so that no tensile stresses appear. In the paper, the authors discuss the application of partially spherical shell to huge off-shore structures. Structural analysis by using the finite element method were done in order to investigate the feasibility of the structure. The results were arranged as to certain parameters to derive design charts by which the stresses of check points can be presumed. Optimum shape is also discussed. (auth.)

Physical Modelling of Geotechnical Structures in Ports and Offshore

Directory of Open Access Journals (Sweden)

Bałachowski Lech

2017-04-01

Full Text Available The physical modelling of subsoil behaviour and soil-structure interaction is essential for the proper design of offshore structures and port infrastructure. A brief introduction to such modelling of geoengineering problems is presented and some methods and experimental devices are described. The relationships between modelling scales are given. Some examples of penetration testing results in centrifuge and calibration chamber are presented. Prospects for physical modelling in geotechnics are also described.

Investigation on asymmetric flow over a blunt-nose slender body at high angle of attack

Science.gov (United States)

Zhongyang, Qi; Yankui, Wang; Lei, Wang; Qian, Li

2017-12-01

The asymmetric vortices over a blunt-nose slender body are investigated experimentally and numerically at a high angle of attack (AoA, α = 50°) and a Reynolds number of Re D = 1.54 × 105 on the basis of an incoming free-stream velocity and diameter (D) of the model. A micro-perturbation in the form of a hemispherical protrusion with a radius of r = 0.012D is introduced and attached on the nose of the slender body to control the behavior of the asymmetric vortices. Given the predominant role of micro perturbation in the asymmetric vortex pattern, a square wave, which is singly periodic, is observed for side-force variation by setting the circumferential angle (θ) of the micro perturbation from 0° to 360°. The asymmetric vortex pattern and the corresponding side force are manageable and highly dependent on the location of perturbation. The flow structure over the blunt-nose slender body is clarified by building a physical model of asymmetric vortex flow structure in a regular state at a high AoA (α = 50°). This model is divided into several regions by flow structure development along the model body-axis, i.e., inception region at x/D ≤ 3.0, triple-vortex region at 3.0 ≤ x/D ≤ 6.0, four-vortex region at 6.0 ≤ x/D ≤ 8.5, and five-vortex region at 8.5 ≤ x/D ≤ 12. The model reveals a complicated multi-vortex system. The associated pressure distributions and flow characteristics are discussed in detail.

Modified Displacement Transfer Functions for Deformed Shape Predictions of Slender Curved Structures with Varying Curvatives

Science.gov (United States)

Ko, William L.; Fleischer, Van Tran

2014-01-01

To eliminate the need to use finite-element modeling for structure shape predictions, a new method was invented. This method is to use the Displacement Transfer Functions to transform the measured surface strains into deflections for mapping out overall structural deformed shapes. The Displacement Transfer Functions are expressed in terms of rectilinearly distributed surface strains, and contain no material properties. This report is to apply the patented method to the shape predictions of non-symmetrically loaded slender curved structures with different curvatures up to a full circle. Because the measured surface strains are not available, finite-element analysis had to be used to analytically generate the surface strains. Previously formulated straight-beam Displacement Transfer Functions were modified by introducing the curvature-effect correction terms. Through single-point or dual-point collocations with finite-elementgenerated deflection curves, functional forms of the curvature-effect correction terms were empirically established. The resulting modified Displacement Transfer Functions can then provide quite accurate shape predictions. Also, the uniform straight-beam Displacement Transfer Function was applied to the shape predictions of a section-cut of a generic capsule (GC) outer curved sandwich wall. The resulting GC shape predictions are quite accurate in partial regions where the radius of curvature does not change sharply.

Offshoring R&D

DEFF Research Database (Denmark)

Hansen, Zaza Nadja Lee; Rasmussen, Lauge Baungaard

2010-01-01

Companies are increasingly offshoring R&D activities. Many firms, however, experience difficulties related to virtual teamwork across cultures and time zones. The research question is: How does increasing R&D offshoring impact transparency of communication structures and knowledge sharing? Using...... case studies from Danish multinational corporations with R&D activities in China, India or Eastern Europe this paper analyses the impact observed in these companies in regard to communication structures and knowledge sharing in management of offshored R&D activities. The findings show that companies...... attempt to increase transparency through formalisation of knowledge and clear communication structures. However, the influence of tacit knowledge, horizontal communication and culture seem largely overlooked. Therefore the authors suggest a context based approach to transparency accustomed...

A mutable slender glume gene in rice (Oryza sativa L.)

Energy Technology Data Exchange (ETDEWEB)

Okumoto, Yutaka; Teraishi, Masayosi; Tanisaka, Takatoshi [Kyoto Univ. (Japan). Graduate School of Agriculture; Yamagata, Hirotada; Horibata, Akira [Kinki Univ., Uchida, Osaka (Japan)

1999-07-01

Identification of genetic factors involved in the mutability of slender glume was made for further understanding of active transposable elements or epigenetic transformation in the rice genome. The results indicated that slender glume mutation is induced with a single recessive mutable gene, slg. The rate of reverse mutation was little affected by crossing, backcrossing, genetic background or cytoplasmic factors. To examine the inheritance of mutability in slg, the reverse mutation rate was evaluated using the progenies of F{sub 2}, F{sub 3}, BC{sub 1}F{sub 2} and BC{sub 1}F{sub 3} SGPs. It was suggested that background and cytoplasmic factors did not have noticeable effects on the reverse mutation frequency (RMF) thus on the mutability of slg. In most cases, the lines derived from slender glume panicles included slender glume plants (SGPs) in a ratio of more than 90%, while those derived from normal glume panicles did in a ratio of 10-20%. Thus, the genotype was concluded as slg/slg for the slender panicles and slg/+ for the normal ones, suggesting that the outer layer of the normal glumes in chimeric plants (CPs) has a genotype slg/+, whereas the inner one including embryo has a genotype of slg/slg. The appearance of such chimera plant is a clear indication of the occurrence of reverse mutation during mitosis as well as meiosis. RFLP linkage analysis showed that slg locus was located between XNpb33 and R1440 with the recombination values of 3.1 and 1.0 cM, respectively. The slg locus was identified to localize on the overlapping region of two YAC clones, Y1774 and Y3356 and the length of this region was assumed to be less than 280 kb. (M.N.)

Reliability-Based Optimal Design of Experiment Plans for Offshore Structures

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard; Faber, Michael Havbro; Kroon, I. B.

1993-01-01

Design of cost optimal experiment plans on the basis of a preposterior analysis is discussed. In particular the planning of on-site response measurements on offshore structures in order to update probabilistic models for fatigue life estimation is addressed. Special emphasis is given to modelling...

The effect of corrosion on the structural reliability of steel offshore structures

International Nuclear Information System (INIS)

Melchers, Robert E.

2005-01-01

This paper considers essential theoretical concepts and data requirements for engineering structural reliability assessment suitable for the estimation of the safety and reliability of corroding ships, offshore structures and pipelines. Such infrastructure operates in a harsh environment. Allowance must be made for structural deterioration since protective measures such as paint coatings, galvanizing or cathodic protection may be ineffective. Reliability analysis requires accurate engineering models for the description and prediction of material corrosion loss and for the maximum depth of pitting. New probability-based models for both these forms of corrosion have been proposed recently and calibrated against a wide range of data. The effects of water velocity and of water pollution are reviewed and compared with recently reported field data for a corrosion at an offshore oil platform. The data interpreted according to the model show good correlation when allowance is made for the season of first immersion and the adverse effects of seawater velocity and of water pollution. An example is given to illustrate the application of reliability analysis to a pipeline subject to pitting corrosion. An important outcome is that good quality estimation of the longer-term probability of loss of structural integrity requires good modelling of the longer-term corrosion behaviour. This is usually associated with anaerobic corrosion. As a result, it cannot be extrapolated from data for short-term corrosion as this is associated with aerobic corrosion conditions

The effect of corrosion on the structural reliability of steel offshore structures

Energy Technology Data Exchange (ETDEWEB)

Melchers, Robert E. [Centre for Infrastructure Performance and Reliability, Department of Civil, Surveying and Environmental Engineering, School of Engineering, University of Newcastle, University Drive, Callaghan NSW 2300 (Australia)]. E-mail: rob.melchers@newcastle.edu.au

2005-10-01

This paper considers essential theoretical concepts and data requirements for engineering structural reliability assessment suitable for the estimation of the safety and reliability of corroding ships, offshore structures and pipelines. Such infrastructure operates in a harsh environment. Allowance must be made for structural deterioration since protective measures such as paint coatings, galvanizing or cathodic protection may be ineffective. Reliability analysis requires accurate engineering models for the description and prediction of material corrosion loss and for the maximum depth of pitting. New probability-based models for both these forms of corrosion have been proposed recently and calibrated against a wide range of data. The effects of water velocity and of water pollution are reviewed and compared with recently reported field data for a corrosion at an offshore oil platform. The data interpreted according to the model show good correlation when allowance is made for the season of first immersion and the adverse effects of seawater velocity and of water pollution. An example is given to illustrate the application of reliability analysis to a pipeline subject to pitting corrosion. An important outcome is that good quality estimation of the longer-term probability of loss of structural integrity requires good modelling of the longer-term corrosion behaviour. This is usually associated with anaerobic corrosion. As a result, it cannot be extrapolated from data for short-term corrosion as this is associated with aerobic corrosion conditions.

Flexi-structure will cut offshore costs

Energy Technology Data Exchange (ETDEWEB)

Laird, R.

1978-03-23

A new support-tower design called Triflex, from Sea Energy Associates, could be used as a single-point mooring for tanker loading for small oilfields as well as for many other offshore production purposes. Triflex is a rigid tower designed to yield and move in sympathy with imposed wave and current forces when they exceed a predetermined limit. The tower can carry up to 4000 tons in water depths up to 300 m, and is lighter, is less expensive, and probably has greater safety advantages for rough conditions than existing North Sea structures. Extensive model testing has been carried out at Lanchester Polytechnic. Four different methods of construction are described.

IDENTIFICATION AND MAPPING OF A GENE FOR RICE SLENDER KERNEL USING Oryza glumaepatula INTROGRESSION LINES

Directory of Open Access Journals (Sweden)

Sobrizal Sobrizal

2016-10-01

Full Text Available World demand for superior rice grain quality tends to increase. One of the  criteria of appearance quality of rice grain is grain shape. Rice consumers  exhibit wide preferences for grain shape, but most Indonesian rice consumers prefer long and slender grain. The objectives of this study were to identify and map a gene for rice slender kernel trait using Oryza  glumaepatula introgression lines with O. sativa cv. Taichung 65 genetic background. A segregation analysis of BC4F2 population derived from backcrosses of a donor parent O. glumaepatula into a recurrent parent Taichung 65 showed that the slender kernel was controlled by a single recessive gene. This new identified gene was designated as sk1 (slender kernel 1. Moreover, based on the RFLP analyses using 14 RFLP markers located on chromosomes 2, 8, 9, and 10 in which the O. glumaepatula chromosomal segments were retained in BC4F2 population, the sk1 was located between RFLP markers C679 and C560 on the long arm of chromosome 2, with map distances of 2.8 and 1.5 cM, respectively. The wild rice O. glumaepatula carried a recessive allele for slender kernel. This allele may be useful in breeding of rice with slender kernel types. In addition, the development of plant materials and RFLP map associated with slender kernel in this study is the preliminary works in the effort to isolate this important grain shape gene.

The effects of exposure to slender and muscular images on male body dissatisfaction.

Science.gov (United States)

Galioto, Rachel; Crowther, Janis H

2013-09-01

This research examined the effects of appearance-based comparisons to muscular and slender idealized male bodies and the contribution of internalization and social comparison to change in body dissatisfaction. Participants were 111 male undergraduates who completed measures of body dissatisfaction, internalization, and social comparison and viewed images of either muscular or slender men in advertisements or product-only advertisements. Results indicated that exposure to both muscular and slender images was associated with an increase in body dissatisfaction, with no significant differences in the change in body dissatisfaction between the two image conditions. Internalization and trait social comparison were each associated with an increase in body dissatisfaction; however, upward social comparison was only a significant predictor of a change in body dissatisfaction for the males who viewed muscular images. These results highlight the impact of slender models on young men's body dissatisfaction and support the examination of media literacy interventions with this population. Copyright © 2013 Elsevier Ltd. All rights reserved.

Gradient based structural optimization with fatigue constraints of jacket structures for offshore wind turbines

DEFF Research Database (Denmark)

Oest, Jacob; Overgaard, Lars Christian; Lund, Erik

2015-01-01

design phase. The key challenge is to efficiently deal with the very large number of non-linear fatigue constraints and the very large time-history loads that are used in the design of offshore support structures. In this paper main emphasis will be on the analytical design sensitivity analysis used...

Breaking wave impact forces on truss support structures for offshore wind turbines

Science.gov (United States)

Cieślikiewicz, Witold; Gudmestad, Ove T.; Podrażka, Olga

2014-05-01

Due to depletion of the conventional energy sources, wind energy is becoming more popular these days. Wind energy is being produced mostly from onshore farms, but there is a clear tendency to transfer wind farms to the sea. The foundations of offshore wind turbines may be truss structures and might be located in shallow water, where are subjected to highly varying hydrodynamic loads, particularly from plunging breaking waves. There are models for impact forces prediction on monopiles. Typically the total wave force on slender pile from breaking waves is a superposition of slowly varying quasi-static force, calculated from the Morison equation and additional dynamical, short duration force due to the impact of the breaker front or breaker tongue. There is not much research done on the truss structures of wind turbines and there are still uncertainties on slamming wave forces, due to plunging breaking waves on those structures. Within the WaveSlam (Wave slamming forces on truss structures in shallow water) project the large scale tests were carried out in 2013 at the Large Wave Flume in Forschungszentrum Küste (FZK) in Hannover, Germany. The following institutions participated in this initiative: the University of Stavanger and the Norwegian University of Science and Technology (project management), University of Gdańsk, Poland, Hamburg University of Technology and the University of Rostock, Germany and Reinertsen AS, Norway. This work was supported by the EU 7th Framework Programme through the grant to the budget of the Integrating Activity HYDRALAB IV. The main aim of the experiment was to investigate the wave slamming forces on truss structures, development of new and improvement of existing methods to calculate forces from the plunging breakers. The majority of the measurements were carried out for regular waves with specified frequencies and wave heights as well as for the irregular waves based on JONSWAP spectrum. The truss structure was equipped with both

Forces and moments on a slender, cavitating body

Energy Technology Data Exchange (ETDEWEB)

Hailey, C.E.; Clark, E.L.; Buffington, R.J.

1988-01-01

Recently a numerical code has been developed at Sandia National Laboratories to predict the pitching moment, normal force, and axial force of a slender, supercavitating shape. The potential flow about the body and cavity is calculated using an axial distribution of source/sink elements. The cavity surface is assumed to be a constant pressure streamline, extending beyond the base of the model. Slender body approximation is used to model the crossflow for small angles of attack. A significant extension of previous work in cavitation flow is the inclusion of laminar and turbulent boundary layer solutions on the body. Predictions with this code, for axial force at zero angle of attack, show good agreement with experiments. There are virtually no published data availble with which to benchmark the pitching moment and normal force predictions. An experiment was designed to measure forces and moments on a supercavitation shape. The primary reason for the test was to obtain much needed data to benchmark the hydrodynamic force and moment predictions. Since the numerical prediction is for super cavitating shapes at very small cavitation numbers, the experiment was designed to be a ventilated cavity test. This paper describes the experimental procedure used to measure the pitching moment, axial and normal forces, and base pressure on a slender body with a ventilated cavity. Limited results are presented for pitching moment and normal force. 5 refs., 7 figs.

Risk Assessment Method for Offshore Structure Based on Global Sensitivity Analysis

Directory of Open Access Journals (Sweden)

Zou Tao

2012-01-01

Full Text Available Based on global sensitivity analysis (GSA, this paper proposes a new risk assessment method for an offshore structure design. This method quantifies all the significances among random variables and their parameters at first. And by comparing the degree of importance, all minor factors would be negligible. Then, the global uncertainty analysis work would be simplified. Global uncertainty analysis (GUA is an effective way to study the complexity and randomness of natural events. Since field measured data and statistical results often have inevitable errors and uncertainties which lead to inaccurate prediction and analysis, the risk in the design stage of offshore structures caused by uncertainties in environmental loads, sea level, and marine corrosion must be taken into account. In this paper, the multivariate compound extreme value distribution model (MCEVD is applied to predict the extreme sea state of wave, current, and wind. The maximum structural stress and deformation of a Jacket platform are analyzed and compared with different design standards. The calculation result sufficiently demonstrates the new risk assessment method’s rationality and security.

Basic studies on design supporting system of offshore structure. Part 2. Implementation of structural design supporting system of offshore structures; Kaiyo kozobutsu wo taisho to shita sekkei shien system ni kansuru kisoteki kenkyu. 2. Kaiyo kozobutsu no kozo sekkei shien system no kochiku

Energy Technology Data Exchange (ETDEWEB)

Nomoto, T.; Hamada, K.; Aoyama, K. [The University of Tokyo, Tokyo (Japan)

1996-12-31

In order to improve the existing design-supporting system for offshore structures, new functions are added to evaluate information of the products, especially those for structural designs. The structural analysis system should be provided with a function of design modification, to efficiently support the structural analysis of these structures. The new system adds hierarchy of various offshore structure models and three-dimensional dimensions to clarify structural and geometrical constraints and design-modification function. The design-modification function is included by use of the hierarchy. The other new functions are finite element analysis systems for the main structure and components, and rigidity calculation for the main structure. The main structure and functional element models are confirmed to be useful also for utilization of information, and provide necessary information of the product models. 11 refs., 11 figs.

Basic studies on design supporting system of offshore structure. Part 2. Implementation of structural design supporting system of offshore structures; Kaiyo kozobutsu wo taisho to shita sekkei shien system ni kansuru kisoteki kenkyu. 2. Kaiyo kozobutsu no kozo sekkei shien system no kochiku

Energy Technology Data Exchange (ETDEWEB)

Nomoto, T; Hamada, K; Aoyama, K [The University of Tokyo, Tokyo (Japan)

1997-12-31

In order to improve the existing design-supporting system for offshore structures, new functions are added to evaluate information of the products, especially those for structural designs. The structural analysis system should be provided with a function of design modification, to efficiently support the structural analysis of these structures. The new system adds hierarchy of various offshore structure models and three-dimensional dimensions to clarify structural and geometrical constraints and design-modification function. The design-modification function is included by use of the hierarchy. The other new functions are finite element analysis systems for the main structure and components, and rigidity calculation for the main structure. The main structure and functional element models are confirmed to be useful also for utilization of information, and provide necessary information of the product models. 11 refs., 11 figs.

Soil-Structure Interaction For Nonslender, Large-Diameter Offshore Monopiles

DEFF Research Database (Denmark)

Sørensen, Søren Peder Hyldal

Strong political and industrial forces, especially in Northern Europe, support the development of new technologies as well as improvements of existing technologies within the field of renewable energy. Offshore wind power is a domestic, sustainable and largely untapped energy resource. Today......, the modern offshore wind turbine offers competitive production prices compared to other sources of renewable energy. Therefore, it is a key technology in breaking the dependence on fossil fuels and in achieving the energy and climate goals of the future. For offshore wind turbines, the costs of foundation...... typically constitutes 20-30 % of the total costs. Hence, improved methods for the design of foundations for offshore wind turbines can increase the competitiveness of offshore wind energy significantly. The monopile foundation concept has been employed as the foundation for the majority of the currently...

Fundamento estadístico del efecto aleatorio del viento para el cálculo de estructuras delgadas. // Statistical foundation of wind random effect for the calculation of slender structures.

Directory of Open Access Journals (Sweden)

C. Fabré Sentile

2006-05-01

Full Text Available En el presente artículo se muestra una interesante recopilación estadística de las características aleatorias del viento convistas a considerar sus efectos de carga sobre estructuras esbeltas, se muestra el resultado hallado en varias fuentesbibliográficas tomando en cuenta además lo planteado por diversas normas al respecto. Se establecen parámetrosestadísticos, tales como autocorrelación, autocovarianza, función de densidad espectral, etc., en función de la acción delviento.Palabras claves: Estructuras esbeltas, efecto aleatorio, análisis estadístico de cargas, estadística.________________________________________________________________________________Abstract.In this paper is shown an interesting statistical summary of the random characteristics of the wind with a view toconsidering its load effects on slender structures, considering several bibliographical sources and taking into account thatoutlined by diverse norms in this respect. Statistical parameters are settle down in function of the wind action.Key words: Slender structures, random effect, statistical analysis, statistic.

Structural health monitoring tools for late and end of life management of offshore wind turbines

DEFF Research Database (Denmark)

McGugan, Malcolm; McKirdy, Scott

2016-01-01

The late and end of life stages in an offshore wind turbines (OWT) life cycle have unique features that must be considered. The initial focus on risks associated with start-up issues due to design, manufacturing or process elements gives way to a stable period of operation and maintenance...... margins and the predominance of low redundancy structures, accurate structural health monitoring can play a strong role in safe management and enable increased operating time at end of life and decommissioning. Late life operations of offshore wind farms can pose significant challenges, balancing...

Assessment of natural frequency of installed offshore wind turbines using nonlinear finite element model considering soil-monopile interaction

Directory of Open Access Journals (Sweden)

Djillali Amar Bouzid

2018-04-01

Full Text Available A nonlinear finite element model is developed to examine the lateral behaviors of monopiles, which support offshore wind turbines (OWTs chosen from five different offshore wind farms in Europe. The simulation is using this model to accurately estimate the natural frequency of these slender structures, as a function of the interaction of the foundations with the subsoil. After a brief introduction to the wind power energy as a reliable alternative in comparison to fossil fuel, the paper focuses on concept of natural frequency as a primary indicator in designing the foundations of OWTs. Then the range of natural frequencies is provided for a safe design purpose. Next, an analytical expression of an OWT natural frequency is presented as a function of soil-monopile interaction through monopile head springs characterized by lateral stiffness KL, rotational stiffness KR and cross-coupling stiffness KLR, of which the differences are discussed. The nonlinear pseudo three-dimensional finite element vertical slices model has been used to analyze the lateral behaviors of monopiles supporting the OWTs of different wind farm sites considered. Through the monopiles head movements (displacements and rotations, the values of KL, KR and KLR were obtained and substituted in the analytical expression of natural frequency for comparison. The comparison results between computed and measured natural frequencies showed an excellent agreement for most cases. This confirms the convenience of the finite element model used for the accurate estimation of the monopile head stiffness. Keywords: Nonlinear finite element analysis, Vertical slices model, Monopiles under horizontal loading, Natural frequency, Monopile head stiffness, Offshore wind turbines (OWTs

Structural Integrity Management for Fixed Offshore Platforms in Malaysia

OpenAIRE

Narayanan Sambu Potty; Mohammad Kabir B. Mohd Akram

2009-01-01

Structural Integrity Management (SIM) is important for the protection of offshore crew, environment, business assets and company and industry reputation. API RP 2A contained guidelines for assessment of existing platforms mostly for the Gulf of Mexico (GOM). ISO 19902 SIM framework also does not specifically cater for Malaysia. There are about 200 platforms in Malaysia with 90 exceeding their design life. The Petronas Carigali Sdn Bhd (PCSB) uses the Asset Integrity Management ...

A CAD model for energy efficient offshore structures for desalination and energy generation

Directory of Open Access Journals (Sweden)

R. Rahul Dev,

2016-09-01

Full Text Available This paper presents a ‘Computer Aided Design (CAD’ model for energy efficient design of offshore structures. In the CAD model preliminary dimensions and geometric details of an offshore structure (i.e. semi-submersible are optimized to achieve a favorable range of motion to reduce the energy consumed by the ‘Dynamic Position System (DPS’. The presented model allows the designer to select the configuration satisfying the user requirements and integration of Computer Aided Design (CAD and Computational Fluid Dynamics (CFD. The integration of CAD with CFD computes a hydrodynamically and energy efficient hull form. Our results show that the implementation of the present model results into an design that can serve the user specified requirements with less cost and energy consumption.

Evaluating stress analysis and failure criteria for offshore structures for Pechora Sea conditions

Science.gov (United States)

Nesic, S.; Donskoy, Y.; Zolotukhin, A.

2017-12-01

Development of Arctic hydrocarbon resources has faced many challenges due to sensitive environmental conditions including low temperatures, ice cover and terrestrial permafrost and extreme seasonal variation in sunlight. Russian offshore field development in Arctic region is usually associated with annual ice cover, which can cause serious damage on the offshore platforms. The Pechora Sea has claimed as one of the most perspective oil and gas region of the Russian Arctic with seven discovered oil and gas fields and several dozens of structures. Our rough assessment, based on in-place hydrocarbon volumes and recovery factor evaluation concept, indicates that Pechora Sea alone has in-place volumes amounting to ca. 20 billion barrel oil equivalent (BOE). This quantity is enough to secure produced volumes by 2040 exceeding 3 billion BOE [1] that indicates huge resource potential of the region. The environmental conditions are primarily function of water dynamics and ice cover. The sea is covered by the ice for greatest part of the year. In this article, the ice load simulations were performed using explicit dynamic analysis system in ANSYS software to determine best shape and size of an offshore platform for the Pechora Sea ice conditions. Different gravity based structures (GBS) were analyzed: artificial island, hollow cylindrical and conical concrete structures and four-leg GBS. Relationships between the stress, deformations and time were analyzed and important observations from the simulation results were a basis for selecting the most preferable structures.

Offshoring medium‐skill tasks, low‐skill unemployment and the skill‐wage structure

NARCIS (Netherlands)

Vallizadeh, Ehssan; Muysken, Joan; Ziesemer, Thomas

2016-01-01

This paper studies the direct and indirect channels through which offshoring affects the domestic skillwage structure and employment opportunities. To identify these channels, we develop a task-based model with unemployment that accounts for skill heterogeneity and endogenous allocation of domestic

Numerical Experiments of Counterflowiing Jet Effects on Supersonic Slender-Body Configurations

Science.gov (United States)

Venkatachari, Balaji Shankar; Mullane, Michael; Cheng, Gary C.; Chang, Chau-Lyan

2015-01-01

Previous studies have demonstrated that the use of counterflowing jets can greatly reduce the drag and heat loads on blunt-body geometries, especially when the long penetration mode jet condition can be established. Previously, the authors had done some preliminary numerical studies to determine the ability to establish long penetration mode jets on a typical Mach 1.6 slender configuration, and study its impact on the boom signature. The results indicated that a jet with a longer penetration length was required to achieve any impact on the boom signature of a typical Mach 1.6 slender configuration. This paper focuses on an in-depth parametric study, done using the space-time conservation element solution element Navier-Stokes flow solver, for investigating the effect of various counterflowing jet conditions/configurations on two supersonic slender-body models (cone-cylinder and quartic body of revolution). The study is aimed at gaining a better understanding of the relationship between the shock penetration length and reduction of drag and boom signature for these two supersonic slender-body configurations. Different jet flow rates, Mach numbers, nozzle jet exit diameters and jet-to-base diameter ratios were examined. The results show the characteristics of a short-to-long-to-short penetration-mode pattern with the increase of jet mass flow rates, observed across various counterflowing jet nozzle configurations. Though the optimal shock penetration length for potential boom-signature mitigation is tied to the long penetration mode, it often results in a very unsteady flow and leads to large oscillations of surface pressure and drag. Furthermore, depending on the geometry of the slender body, longer jet penetration did not always result in maximum drag reduction. For the quartic geometry, the maximum drag reduction corresponds well to the longest shock penetration length, while this was not the case for the cone-cylinder-as the geometry was already optimized for

Controlling cyclic stiffness of a foundation, by manipulating the deformation history

DEFF Research Database (Denmark)

Sabaliauskas, Tomas; Ibsen, Lars Bo

2018-01-01

Offshore wind turbines are slender structures, dynamic response of which depends on foundation stiffness. Unfortunately, foundations embedded in sand can become disturbed, their stiffness can increase and decrease episodically. To investigate the phenomenon governing loss and recovery of stiffnes...

Wind Loads on Ships and Offshore Structures Estimated by CFD

DEFF Research Database (Denmark)

Aage, Christian; Hvid, S.L.; Hughes, P.H.

1997-01-01

Wind loads on ships and offshore structures could until recently be determined only by model tests, or by statistical methods based on model tests. By the development of Computational Fluid Dynamics or CFD there is now a realistic computational alternative available. In this paper, wind loads...... on a seagoing ferry and on a semisubmersible offshore platform have been estimated by CFD. The results have been compared with wind tunnel model tests and, for the ferry, a few full-scale measurements, and good agreement is obtained. The CFD method offers the possibility of a computational estimate of scale...... effects related to wind tunnel model testing. An example of such an estimate on the ferry is discussed. Due to the time involved in generating the computational mesh and in computing the solution, the CFD method is not at the moment economically competitive to routine wind tunnel model testing....

The Hidden Costs of Offshoring

DEFF Research Database (Denmark)

Møller Larsen, Marcus; Manning, Stephan; Pedersen, Torben

2011-01-01

of offshoring. Specifically, we propose that hidden costs can be explained by the combination of increasing structural, operational and social complexity of offshoring activities. In addition, we suggest that firm orientation towards organizational design as part of an offshoring strategy and offshoring......This study seeks to explain hidden costs of offshoring, i.e. unexpected costs resulting from the relocation of business tasks and activities outside the home country. We develop a model that highlights the role of complexity, design orientation and experience in explaining hidden costs...... experience moderate the relationship between complexity and hidden costs negatively i.e. reduces the cost generating impact of complexity. We develop three hypotheses and test them on comprehensive data from the Offshoring Research Network (ORN). In general, we find support for our hypotheses. A key result...

Operational management of offshore energy assets

Science.gov (United States)

Kolios, A. J.; Martinez Luengo, M.

2016-02-01

Energy assets and especially those deployed offshore are subject to a variety of harsh operational and environmental conditions which lead to deterioration of their performance and structural capacity over time. The aim of reduction of CAPEX in new installations shifts focus to operational management to monitor and assess performance of critical assets ensuring their fitness for service throughout their service life and also to provide appropriate and effective information towards requalification or other end of life scenarios, optimizing the OPEX. Over the last decades, the offshore oil & gas industry has developed and applied various approaches in operational management of assets through Structural Health and Condition Monitoring (SHM/CM) systems which can be, at a certain level, transferable to offshore renewable installations. This paper aims to highlight the key differences between offshore oil & gas and renewable energy assets from a structural integrity and reliability perspective, provide a comprehensive overview of different approaches that are available and applicable, and distinguish the benefits of such systems in the efficient operation of offshore energy assets.

Probabilistic Fatigue Analysis of Jacket Support Structures for Offshore Wind Turbines Exemplified on Tubular Joints

OpenAIRE

Kelma, Sebastian; Schaumann, Peter

2015-01-01

The design of offshore wind turbines is usually based on the semi-probabilistic safety concept. Using probabilistic methods, the aim is to find an advanced structural design of OWTs in order to improve safety and reduce costs. The probabilistic design is exemplified on tubular joints of a jacket substructure. Loads and resistance are considered by their respective probability distributions. Time series of loads are generated by fully-coupled numerical simulation of the offshore wind turbine. ...

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

OpenAIRE

Echeverry Jaramillo, Sara; Le Sourne, Hervé; Bela, Andreea; Pire, Timothée; Rigo, Philippe

2017-01-01

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

Análisis de pérdida de estabilidad no lineal de elementos estructurales sometidos a compresión. // Slender structural elements non lineal stability analysis.

Directory of Open Access Journals (Sweden)

C. Fabré Sentile

2007-01-01

Full Text Available En el presente artículo se muestra el análisis de perdida de estabilidad en elementos estructurales delgados bajocompresión. Se realiza la exposición de las consideraciones del análisis lineal y no lineal de perdida de estabilidad y seejemplifica con una estructura modelada mediante elementos finitos, estableciéndose conclusiones interesantes.Palabras claves: Estructuras esbeltas, estabilidad no-lineal, Euler.______________________________________________________________________________Abstract:Presently paper deals with stability analysis in structural elements. The considerations of lineal and non lineal analysis ofstability are exposed and it is exemplified with a finite element structure model, settling down interesting conclusions.Key words: Slender structures, non-lineal stability, Euler.

Structural health and prognostics management for offshore wind turbines :

Energy Technology Data Exchange (ETDEWEB)

Griffith, Daniel; Resor, Brian Ray; White, Jonathan Randall; Paquette, Joshua A.; Yoder, Nathanael C.

2012-12-01

Operations and maintenance costs for offshore wind plants are expected to be significantly higher than the current costs for onshore plants. One way in which these costs may be able to be reduced is through the use of a structural health and prognostic management system as part of a condition based maintenance paradigm with smart load management. To facilitate the creation of such a system a multiscale modeling approach has been developed to identify how the underlying physics of the system are affected by the presence of damage and how these changes manifest themselves in the operational response of a full turbine. The developed methodology was used to investigate the effects of a candidate blade damage feature, a trailing edge disbond, on a 5-MW offshore wind turbine and the measurements that demonstrated the highest sensitivity to the damage were the local pitching moments around the disbond. The multiscale method demonstrated that these changes were caused by a local decrease in the blades torsional stiffness due to the disbond, which also resulted in changes in the blades local strain field. Full turbine simulations were also used to demonstrate that derating the turbine power by as little as 5% could extend the fatigue life of a blade by as much as a factor of 3. The integration of the health monitoring information, conceptual repair cost versus damage size information, and this load management methodology provides an initial roadmap for reducing operations and maintenance costs for offshore wind farms while increasing turbine availability and overall profit.

The Seismic Reliability of Offshore Structures Based on Nonlinear Time History Analyses

International Nuclear Information System (INIS)

Hosseini, Mahmood; Karimiyani, Somayyeh; Ghafooripour, Amin; Jabbarzadeh, Mohammad Javad

2008-01-01

Regarding the past earthquakes damages to offshore structures, as vital structures in the oil and gas industries, it is important that their seismic design is performed by very high reliability. Accepting the Nonlinear Time History Analyses (NLTHA) as the most reliable seismic analysis method, in this paper an offshore platform of jacket type with the height of 304 feet, having a deck of 96 feet by 94 feet, and weighing 290 million pounds has been studied. At first, some Push-Over Analyses (POA) have been preformed to recognize the more critical members of the jacket, based on the range of their plastic deformations. Then NLTHA have been performed by using the 3-components accelerograms of 100 earthquakes, covering a wide range of frequency content, and normalized to three Peak Ground Acceleration (PGA) levels of 0.3 g, 0.65 g, and 1.0 g. By using the results of NLTHA the damage and rupture probabilities of critical member have been studied to assess the reliability of the jacket structure. Regarding that different structural members of the jacket have different effects on the stability of the platform, an ''importance factor'' has been considered for each critical member based on its location and orientation in the structure, and then the reliability of the whole structure has been obtained by combining the reliability of the critical members, each having its specific importance factor

Wave kinematics and response of slender offshore structures. Vol 3: Description of measuring systems

Energy Technology Data Exchange (ETDEWEB)

Riber, H.J.

1999-08-01

The report presents the measuring systems used during the measurements in the North Sea at the Tyra field. The report consists of two parts: (1) Description of the wave measuring systems (WMS); (2) Description of the load mesuring system (LMS). The developed Wave Kinematics Measuring Systems (WMS) is an acoustic system based on the pulsed incoherent Doppler technique. Basically it consists of 4 sonar stations and a control and monitoring station. The sonar stations are positioned at the seabed north of the TCP-A platform in a star configuration with one station surrounded by the other three stations in a fixed distance of 37 m. From the central sonar stations an umbilical is routed to the TCP-A platform where the control and monitoring stations is positioned in the satellite communication room. The measurement periods have been concentrated to periods with storms. It was a special emphasis to measure the wave kinematics of extremely high waves. The LMS is described in terms of geometrical data, structural properties, instrumentation, and other characteristics. (LN)

Design guidelines for flexural wave attenuation of slender beams with local resonators

International Nuclear Information System (INIS)

Liu, Yaozong; Yu, Dianlong; Li, Li; Zhao, Honggang; Wen, Jihong; Wen, Xisen

2007-01-01

The complex band structures and attenuation spectra of flexural waves in slender beams with periodically mounted local resonators are investigated with transfer matrix method. It is noteworthy that the frequency range and attenuation coefficient of the locally resonant gap become larger in complex band structures if larger resonators were used. But given the total add-on mass of resonators, the attenuation spectra of finite beams with large but few resonators do not demonstrate such phenomena because the attenuation needs several periods to establish. So with the view of application, a large number of small local resonators widely spread along the beam are preferred given the total add-on mass to the beam

Thermal post-buckling of slender composite and FGM columns ...

Indian Academy of Sciences (India)

G Venkateswara Rao

slender as well as shear flexible FGM columns using the classical Rayleigh–Ritz and ... In the present work, a novel formulation based on the FE method is proposed to ..... absence of any geometric non-linearity, the transverse deflection of the ...

Turbulent skin-friction drag on a slender body of revolution and Gray's Paradox

International Nuclear Information System (INIS)

Nesteruk, Igor; Cartwright, Julyan H E

2011-01-01

The boundary layer on a slender body of revolution differs considerably from that on a flat plate, but these two cases can be connected by the Mangler-Stepanov transformations. The presented analysis shows that turbulent frictional drag on a slender rotationally symmetric body is much smaller than the flat-plate concept gives and the flow can remain laminar at larger Reynolds numbers. Both facts are valid for an unseparated flow pattern and enable us to revise the turbulent drag estimation of a dolphin, presented by Gray 74 years ago, and to resolve his paradox, since experimental data testify that dolphins can achieve flow without separation. The small values of turbulent skin-friction drag on slender bodies of revolution have additional interest for further experimental investigations and for applications of shapes without boundary-layer separation to diminish the total drag and noise of air- and hydrodynamic hulls.

Preliminary design of offshore wind turbine support structures : The importance of proper mode shape estimation

NARCIS (Netherlands)

Van der Male, P.

2013-01-01

Offshore wind turbines are highly exposed to timevarying loads. For support structures, estimation of the fatigue damage during the lifetime of the structure is an essential design aspect. This already applies for the preliminary design stage. In determining the dynamic amplification in the

Optimization of offshore wind turbine support structures using analytical gradient-based method

OpenAIRE

Chew, Kok Hon; Tai, Kang; Ng, E.Y.K.; Muskulus, Michael

2015-01-01

Design optimization of the offshore wind turbine support structure is an expensive task; due to the highly-constrained, non-convex and non-linear nature of the design problem. This report presents an analytical gradient-based method to solve this problem in an efficient and effective way. The design sensitivities of the objective and constraint functions are evaluated analytically while the optimization of the structure is performed, subject to sizing, eigenfrequency, extreme load an...

Structural health and prognostics management for offshore wind turbines :

Energy Technology Data Exchange (ETDEWEB)

Myrent, Noah J.; Kusnick, Joshua F.; Barrett, Natalie C.; Adams, Douglas E.; Griffith, Daniel

2013-04-01

Operations and maintenance costs for offshore wind plants are significantly higher than the current costs for land-based (onshore) wind plants. One way to reduce these costs would be to implement a structural health and prognostic management (SHPM) system as part of a condition based maintenance paradigm with smart load management and utilize a state-based cost model to assess the economics associated with use of the SHPM system. To facilitate the development of such a system a multi-scale modeling approach developed in prior work is used to identify how the underlying physics of the system are affected by the presence of damage and faults, and how these changes manifest themselves in the operational response of a full turbine. This methodology was used to investigate two case studies: (1) the effects of rotor imbalance due to pitch error (aerodynamic imbalance) and mass imbalance and (2) disbond of the shear web; both on a 5-MW offshore wind turbine in the present report. Based on simulations of damage in the turbine model, the operational measurements that demonstrated the highest sensitivity to the damage/faults were the blade tip accelerations and local pitching moments for both imbalance and shear web disbond. The initial cost model provided a great deal of insight into the estimated savings in operations and maintenance costs due to the implementation of an effective SHPM system. The integration of the health monitoring information and O&M cost versus damage/fault severity information provides the initial steps to identify processes to reduce operations and maintenance costs for an offshore wind farm while increasing turbine availability, revenue, and overall profit.

Time Domain Modeling and Simulation of Nonlinear Slender Viscoelastic Beams Associating Cosserat Theory and a Fractional Derivative Model

Directory of Open Access Journals (Sweden)

Adailton S. Borges

Full Text Available Abstract A broad class of engineering systems can be satisfactory modeled under the assumptions of small deformations and linear material properties. However, many mechanical systems used in modern applications, like structural elements typical of aerospace and petroleum industries, have been characterized by increased slenderness and high static and dynamic loads. In such situations, it becomes indispensable to consider the nonlinear geometric effects and/or material nonlinear behavior. At the same time, in many cases involving dynamic loads, there comes the need for attenuation of vibration levels. In this context, this paper describes the development and validation of numerical models of viscoelastic slender beam-like structures undergoing large displacements. The numerical approach is based on the combination of the nonlinear Cosserat beam theory and a viscoelastic model based on Fractional Derivatives. Such combination enables to derive nonlinear equations of motion that, upon finite element discretization, can be used for predicting the dynamic behavior of the structure in the time domain, accounting for geometric nonlinearity and viscoelastic damping. The modeling methodology is illustrated and validated by numerical simulations, the results of which are compared to others available in the literature.

Developments in offshore technology. Entwicklungen in der Offshoretechnik

Energy Technology Data Exchange (ETDEWEB)

1981-01-01

This book contains the summarized lectures held on the 8th of October, 1981 within the first status Seminar 'Offshore technology' which was organized by the Federal Minstry for Research and Technology. Contents are divided into: 1. Offshore-natural gas liquefaction, conveying systems. Offshore-tanker charging with supercold liquiefied gases; development of LNG-offshore - convayance systems; 2.) Development of components and installations in offshore structures: mooving-measuring- and monitoring systems for the installation of the EPOS deck; underwater-piling with a hydraulic-pile hammer; cast steel nodes for offshore-structures (material, calculation, design); 3.) underwater tools: the underwater-working system SUPRA; test results and experience with the unmanned UW-instrument-carrier FUGE; development of a mobile diver assistance vehicle for inspection and maintenance duties; 4.) underwater-pipeline-technique: flexible offshore-pipeline/continuous production and assembly, pipeline assembly at sea according to the J-Method with flash-welding technique; construction and testing of UWAG I (underwater working device) for embedding cables and pipes in the ocean soil.

Offshore windfarms and their impact on fish abundance and community structure

DEFF Research Database (Denmark)

Stenberg, Claus; Dinesen, Grete E.; Deurs, Mikael van

2012-01-01

Deployment of offshore windfarms (OWF) is rapidly expanding. A before–after control impact (BACI) approach was used to study the impact of one of the world’s largest offshore windfarms (Horns Rev Offshore Windfarm) on fish assemblages and species diversity. Fish were generally more abundant in th...

Design of Offshore Wind Turbine Support Structures: Selected topics in the field of geotechnical engineering

DEFF Research Database (Denmark)

Bakmar, Christian LeBlanc

.D. thesis was to enable low-cost and low-risk support structures to be designed in order to improve the economic feasibility of future offshore wind farms. The research work was divided in the following four selected research topics in the field of geotechnical engineering, relating to the monopile......Breaking the dependence on fossil fuels offers many opportunities for strengthened competitiveness, technological development and progress. Offshore wind power is a domestic, sustainable and largely untapped energy resource that provides an alternative to fossil fuels, reduces carbon emissions......, and decreases the economic and supply risks associated with reliance on imported fuels. Today, the modern offshore wind turbine offers competitive production prices for renewable energy and is therefore a key technology in achieving the energy and climate goals of the future. The overall aim of this Ph...

Soil structure interaction in offshore wind turbine collisions

DEFF Research Database (Denmark)

Samsonovs, Artjoms; Giuliani, Luisa; Zania, Varvara

2014-01-01

Vessel impact is one of the load cases which should be accounted for in the design of an offshore wind turbine (OWT) according to design codes, but little guidance or information is given on the employed methodology. This study focuses on the evaluation of the distress induced in a wind turbine...... after a ship collision, thus providing an insight on the consequences of a collision event and on the main aspects to be considered when designing for this load case. In particular, the role of the foundation soil properties (site conditions) on the response of the structural system is investigated....... Dynamic finite element analyses have been performed taking into account the geometric and material nonlinearity of the tower, and the effects of soil structure interaction (SSI) have been studied in two representative collision scenarios of a service vessel with the turbine: a moderate energy impact...

RBI Optimization of Offshore Wind Turbines

DEFF Research Database (Denmark)

Ramírez, José G. Rangel; Sørensen, John Dalsgaard

2009-01-01

methods for oil & gas installations, a framework for optimal inspection and maintenance planning of offshore wind turbines is presented. Special aspects for offshore wind turbines considered are the fatigue loading characteristics where usually the wind loading are dominating the wave loading, wake......Wind turbines for electricity production have increased significantly the last years both in production capability and size. This development is expected to continue also in the coming years. Offshore wind turbines with an electricity production of 5-10 MW are planned. Typically, the wind turbine...... support structure is a steel structure consisting of a tower and a monopile, tripod or jacket type foundation. This paper considers aspects of inspection and maintenance planning of fatigue prone details in jacket and tripod type of wind turbine support structures. Based on risk-based inspection planning...

Scour Forecasting for Offshore Wind Parks

DEFF Research Database (Denmark)

Hartvig, Peres Akrawi

In an effort to minimize the costs of offshore wind parks, the present research deals with optimizing a certain aspect of the support structure, namely the approach to scour. Scour is the phenomenon of seabed changes in the vicinity of the support structure that arises when the support structure......, scour forecasts facilitate the comparison between a scour design based on either deployment of scour-protection or enhanced structural design. The broad goal is to develop a method that produces accurate scour forecasts for offshore wind parks. The present research investigates more specifically which...

Aspects of structural health and condition monitoring of offshore wind turbines.

Science.gov (United States)

Antoniadou, I; Dervilis, N; Papatheou, E; Maguire, A E; Worden, K

2015-02-28

Wind power has expanded significantly over the past years, although reliability of wind turbine systems, especially of offshore wind turbines, has been many times unsatisfactory in the past. Wind turbine failures are equivalent to crucial financial losses. Therefore, creating and applying strategies that improve the reliability of their components is important for a successful implementation of such systems. Structural health monitoring (SHM) addresses these problems through the monitoring of parameters indicative of the state of the structure examined. Condition monitoring (CM), on the other hand, can be seen as a specialized area of the SHM community that aims at damage detection of, particularly, rotating machinery. The paper is divided into two parts: in the first part, advanced signal processing and machine learning methods are discussed for SHM and CM on wind turbine gearbox and blade damage detection examples. In the second part, an initial exploration of supervisor control and data acquisition systems data of an offshore wind farm is presented, and data-driven approaches are proposed for detecting abnormal behaviour of wind turbines. It is shown that the advanced signal processing methods discussed are effective and that it is important to adopt these SHM strategies in the wind energy sector.

Aspects of structural health and condition monitoring of offshore wind turbines

Science.gov (United States)

Antoniadou, I.; Dervilis, N.; Papatheou, E.; Maguire, A. E.; Worden, K.

2015-01-01

Wind power has expanded significantly over the past years, although reliability of wind turbine systems, especially of offshore wind turbines, has been many times unsatisfactory in the past. Wind turbine failures are equivalent to crucial financial losses. Therefore, creating and applying strategies that improve the reliability of their components is important for a successful implementation of such systems. Structural health monitoring (SHM) addresses these problems through the monitoring of parameters indicative of the state of the structure examined. Condition monitoring (CM), on the other hand, can be seen as a specialized area of the SHM community that aims at damage detection of, particularly, rotating machinery. The paper is divided into two parts: in the first part, advanced signal processing and machine learning methods are discussed for SHM and CM on wind turbine gearbox and blade damage detection examples. In the second part, an initial exploration of supervisor control and data acquisition systems data of an offshore wind farm is presented, and data-driven approaches are proposed for detecting abnormal behaviour of wind turbines. It is shown that the advanced signal processing methods discussed are effective and that it is important to adopt these SHM strategies in the wind energy sector. PMID:25583864

Cost-efficient foundation structures for large offshore wind farms

International Nuclear Information System (INIS)

Birch, C.; Gormsen, C.; Lyngesen, S.; Rasmussen, J. L.; Juhl, H.

1997-01-01

This paper presents the results of the development of a cost-efficient foundation for large (1.5 MW) offshore wind farms at water depth of 5 to 11 m. Previously, medium sized wind turbines (500 kW) in Denmark have been installed offshore at water depths of approximately 5 m on concrete gravity foundations. The installation of larger turbines at greater depth does, however, hold great promise in terms of wind environment and environmental considerations. The costs of a traditional gravity foundation at these increased water depths is expected to be prohibitive, and the aim of the project has been to reduce the foundations costs in general. This paper describes the theoretical basis for the geotechnical and structural design of three alternative concepts and presents an optimised layout of each based on a research and development project. The basis has been a wind farm consisting of 100 turbines. The R and D project has been undertaken by the consulting engineers Nellemann, Nielsen and Rauschenberger A/S (Gravity foundation), LICengineering A/S (Mono pile) and Ramboell (Tripod) in co-operation with the Danish utility engineering companies Elkraft and Elsamprojekt A/S. The project was partly financed by the participants and by the Danish Energy Agency through their 1996 Energy Research Programme (EFP-96). (au) 18 refs

Structural Optimization of an Offshore Wind Turbines Transition Pieces for Bucket Foundations

DEFF Research Database (Denmark)

Nezhentseva, Anastasia; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo

Traditionally, offshore constructions are made of steel. The focus of this paper is optimization of a transition piece (TP) connecting the offshore wind turbine column with a suction bucket foundation. Suction caissons, typically used for shallow water depths, have been proved to be adequate...... in residual soil conditions for depths up to approximately 40 m. The existing design practice is limited to the use of steel-flange-reinforced shear panels. Desirable outcome is proposal of an alternative material which does not require extensive welding work. Compact reinforced composite (CRC) is suggested...... curved segments have been introduced between the conical part and the tubular parts of the structure. While the minimum amount of steel and concrete was required for the composite CRC–steel shell model, the pure CRC model appeared to be the least sensitive to geometrical imperfections, corresponding...

Project alliancing in the offshore industry

NARCIS (Netherlands)

Halman, Johannes I.M.; Braks, B.F.M.

In this paper the shift towards new types of project organisation within the Offshore Industry is explained and discussed. Special focus is given to the organisational concept of Project Alliancing. The principles, structure and culture of a Project Alliance as applied within the Offshore Industry

Pricing offshore wind power

International Nuclear Information System (INIS)

Levitt, Andrew C.; Kempton, Willett; Smith, Aaron P.; Musial, Walt; Firestone, Jeremy

2011-01-01

Offshore wind offers a very large clean power resource, but electricity from the first US offshore wind contracts is costlier than current regional wholesale electricity prices. To better understand the factors that drive these costs, we develop a pro-forma cash flow model to calculate two results: the levelized cost of energy, and the breakeven price required for financial viability. We then determine input values based on our analysis of capital markets and of 35 operating and planned projects in Europe, China, and the United States. The model is run for a range of inputs appropriate to US policies, electricity markets, and capital markets to assess how changes in policy incentives, project inputs, and financial structure affect the breakeven price of offshore wind power. The model and documentation are made publicly available. - Highlights: → We calculate the Breakeven Price (BP) required to deploy offshore wind plants. → We determine values for cost drivers and review incentives structures in the US. → We develop 3 scenarios using today's technology but varying in industry experience. → BP differs widely by Cost Scenario; relative policy effectiveness varies by stage. → The low-range BP is below regional market values in the Northeast United States.

Fatigue Life of High-Strength Steel Offshore Tubular Joints

DEFF Research Database (Denmark)

Petersen, Rasmus Ingomar; Agerskov, Henning; Lopez Martinez, Luis

1996-01-01

In the present investigation, the fatigue life of tubular joints in offshore steel structures is studied. Two test series on full-scale tubular joints have been carried through. One series was on joints in conventional offshore structural steel, and the other series was on joints in high-strength......In the present investigation, the fatigue life of tubular joints in offshore steel structures is studied. Two test series on full-scale tubular joints have been carried through. One series was on joints in conventional offshore structural steel, and the other series was on joints in high......-strength steel with a yield stress of 820-830 MPa and with high weldability and toughness properties. The test specimens of both series had the same geometry. The present report concentrates on the results obtained in the investigation on the high-strength steel tubular joints.The test specimens were fabricated...... from Ø 324-610 mm tubes, and the joints were loaded in in-plane bending. Both fatigue tests under constant amplitude loading and tests with a stochastic loading that is realistic in relation to offshore structures, are included in the investigation.A comparison between constant amplitude and variable...

Differences in plankton community structure and carbon cycling along a climate gradient from the Greenland Ice Sheet to offshore waters

DEFF Research Database (Denmark)

Arendt, K.E.; Nielsen, Torkel Gissel; Rysgaard, S.

Huge differences in plankton community structures and biomasses are observed along a climate gradient from the Greenland Ice Sheet to offshore waters at the West Greenland coast. The offshore region has a high biomass of copepods dominated by Calanus spp., which are capable of consuming 55....... Protozooplankton accounts for 20-38% of the carbon turnover in the offshore and inland areas. However, protozooplankton like copepods has low ability to turn over the primary production close to the Ice Sheet. Increased run of from the Greenland Ice Sheet due to global warming could displace the existing climate...... gradient. This would have a profound influence on the future plankton community structure as well as the energy transfer to higher trophic levels in Arctic coastal ecosystems....

P-{Delta} effects on the reliability of oil offshore jacket platforms in Mexico

Energy Technology Data Exchange (ETDEWEB)

De Leon-Escobedo, D. [Universidad Autonoma del Estado de Mexico, Toluca, Estado de Mexico (Mexico)]. E-mail: daviddeleonescobedo@yahoo.com.mx; Campos, D. [Instituto Mexicano del Petroleo (Mexico)]. E-mail: dcampos@imp.mx

2012-07-15

Given the important economic consequences of an oil platform failure, all the aspects of its structural behavior and safety issues need to be carefully considered. In particular, P-{Delta} effects on the deck legs of marine offshore jacket platforms may be relevant when the deck height and the vertical load are significant. In this paper, the impact of the moment amplification, due to slenderness of the deck legs, on the platform safety is examined and appraised from the viewpoint of the structural reliability. The formulation is applied to a typical tall deck marine platform under the environmental loading at the Bay of Campeche, Mexico, and its reliability index is calculated with and without the P-{Delta} effect. The results presented herein may be used to improve the current practice in the design and assessment of offshore marine platforms in Mexico and to update the current version of the code. [Spanish] Dadas las importantes consecuencias economicas de la falla de una plataforma petrolera, todos los aspectos de su comportamiento estructural y aspectos de seguridad necesitan considerarse cuidadosamente. En particular, los efectos P-{Delta} en las piernas de la cubierta de plataformas marinas costa fuera petroleras tipo jacket pueden ser relevantes cuando la altura de la cubierta y la intensidad de cargas verticales son significativas. En este articulo se examina el impacto que sobre la seguridad de la plataforma tiene la amplificacion de momentos, debido a la esbeltez de las piernas de la cubierta, y se evalua este impacto desde el punto de vista de confiabilidad estructural. La formulacion se aplica a una plataforma marina tipica, con cubierta alta, bajo la carga ambiental de la Bahia de Campeche, Mexico y se calcula su indice de confiabilidad con y sin el efecto P-{Delta}. Los resultados presentados aqui pueden usarse para mejorar las practicas actuales de diseno y evaluacion de plataformas marinas costa fuera en Mexico y para actualizar la version actual

ISM Approach to Model Offshore Outsourcing Risks

Directory of Open Access Journals (Sweden)

Sunand Kumar

2014-07-01

Full Text Available In an effort to achieve a competitive advantage via cost reductions and improved market responsiveness, organizations are increasingly employing offshore outsourcing as a major component of their supply chain strategies. But as evident from literature number of risks such as Political risk, Risk due to cultural differences, Compliance and regulatory risk, Opportunistic risk and Organization structural risk, which adversely affect the performance of offshore outsourcing in a supply chain network. This also leads to dissatisfaction among different stake holders. The main objective of this paper is to identify and understand the mutual interaction among various risks which affect the performance of offshore outsourcing.  To this effect, authors have identified various risks through extant review of literature.  From this information, an integrated model using interpretive structural modelling (ISM for risks affecting offshore outsourcing is developed and the structural relationships between these risks are modeled.  Further, MICMAC analysis is done to analyze the driving power and dependency of risks which shall be helpful to managers to identify and classify important criterions and to reveal the direct and indirect effects of each criterion on offshore outsourcing. Results show that political risk and risk due to cultural differences are act as strong drivers.

Turbulent skin-friction drag on a slender body of revolution and Gray's Paradox

Energy Technology Data Exchange (ETDEWEB)

Nesteruk, Igor [Institute of Hydromechanics, National Academy of Sciences of Ukraine, Kyiv (Ukraine); Cartwright, Julyan H E [Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada (Spain)

2011-12-22

The boundary layer on a slender body of revolution differs considerably from that on a flat plate, but these two cases can be connected by the Mangler-Stepanov transformations. The presented analysis shows that turbulent frictional drag on a slender rotationally symmetric body is much smaller than the flat-plate concept gives and the flow can remain laminar at larger Reynolds numbers. Both facts are valid for an unseparated flow pattern and enable us to revise the turbulent drag estimation of a dolphin, presented by Gray 74 years ago, and to resolve his paradox, since experimental data testify that dolphins can achieve flow without separation. The small values of turbulent skin-friction drag on slender bodies of revolution have additional interest for further experimental investigations and for applications of shapes without boundary-layer separation to diminish the total drag and noise of air- and hydrodynamic hulls.

Upwind design basis (WP4 : Offshore foundations and support structures)

NARCIS (Netherlands)

Fischer, T.; De Vries, W.E.; Schmidt, B.

2010-01-01

The presented design basis gives a summarized overview of relevant design properties for a later offshore wind turbine design procedures within work package 4. The described offshore site is located in the Dutch North Sea and has a water depth of 21m. Therefore it will be chosen as shallow site

Initial vesicular-arbuscular mycorrhizal development of slender wheatgrass on two amended mine spoils

Energy Technology Data Exchange (ETDEWEB)

Zak, J.C.; Parkinson, D. (University of Calgary, Calgary, AB (Canada). Dept. of Biology)

1982-01-01

The initial vesicular-arbuscular (VA) mycorrhizal development of slender wheatgrass on extracted oil-sands and subalpine coal-mine spoils, amended with either fertilizer, peat, or liquid sewage sludge, was examined. Plants were sampled at 2,6 and 10 weeks after plant emergence and the level of infection was expressed as length of mycorrhizal root per plant and length of root which contained arbuscules, vesicles, or only hyphae. Mycorrhizal infection of slender wheatgrass on the oil sands was limited to plants on the peat-amended spoil. Infection of plants on the peat-amended oil-sands spoil was detected by 2 weeks. Plants on the subalpine spoil were infected at 2 weeks only on the peat-amended spoil. While slender wheatgrass on the control and fertilizer-amended spoil developed mycorrhizae by 6 weeks, infection was not observed in plants on the sewage-amended spoil until 10 weeks. At 10 weeks, there were no significant differences in lengths of mycorrhizal root per plant among the amendments. Increased P levels in the fertilizer- and sewage-amended subalpine spoil did not suppress VA mycorrhizal development. 43 refs., 6 tabs.

Resolving plate structure across the seismogenic zone in Cascadia from onshore-offshore receiver function imaging

Science.gov (United States)

Audet, P.; Schaeffer, A. J.

2017-12-01

Studies of the forearc structure in the Cascadia subduction zone using teleseismic P-wave receiver function have resolved structures associated with deep fluid cycling, such as the basalt-to-eclogite reaction and fluid overpressure within the subducting oceanic crust, as well as the serpentinization of the forearc mantle wedge. Unfortunately, the updip extent of the over-pressured zone, and therefore the possible control on the transition from episodic slow slip to seismic slip, occurs offshore and is not resolved in those studies. The Cascadia Initiative (CI) has provided an opportunity to extend this work to the locked zone using teleseismic receiver functions from the deployment of a dense line of ocean-bottom seismograph stations offshore of Washington State, from the trench to the coastline. Here we calculate P-wave receiver functions using data from offshore (CI) and onshore (CAFE) broadband seismic stations. These data clearly show the various scattered phases associated with a dipping low-velocity layer that was identified in previous studies as the downgoing oceanic crust. These signals are difficult to untangle offshore because they arrive at similar times. We process receiver functions using a modified common-conversion point (CCP) stacking technique that uses a coherency filter to optimally stack images obtained from the three main scattered phases. The resulting image shows along-dip variations in the character of the seismic discontinuities associated with the top and bottom of the low-velocity layer. Combined with focal depth information of regular and low-frequency earthquakes, these variations may reflect changes in the material properties of the megathrust across the seismogenic zone in Cascadia.

Offshore rectenna feasbility

Science.gov (United States)

Freeman, J. W.; Hervey, D.; Glaser, P.

1980-01-01

A preliminary study of the feasibility and cost of an offshore rectenna to serve the upper metropolitan east coast was performed. A candidate site at which to build a 5 GW rectenna was selected on the basis of proximity to load centers, avoidance of shipping lanes, sea floor terrain, and relocated conditions. Several types of support structures were selected for study based initially on the reference system rectenna concept of a wire mesh ground screen and dipoles each with its own rectifier and filter circuits. Possible secondary uses of an offshore rectenna were examined and are evaluated.

Analysis of the Nonlinear Static and Dynamic Behavior of Offshore Structures

KAUST Repository

Alfosail, Feras

2015-01-01

Understanding static and dynamic nonlinear behavior of pipes and risers is crucial for the design aspects in offshore engineering fields. In this work, we examine two nonlinear problems in offshore engineering field: vortex Induced vibration

Reliability-based assessment of deteriorating ship-shaped offshore structures

Energy Technology Data Exchange (ETDEWEB)

Ayala-Uraga, Efren

2009-11-15

Floating production, storage and off loading ships, referred to as FPSOs, are hybrid structures in the sense that these vessels are ships being operated as offshore facilities. Production ships or FPSOs constitute an efficient solution for remote oil field locations due to their storage capacity of crude oil. Production ships are either tanker conversions or purpose-built vessels. Most of the applications of production ships are converted ocean-going oil tankers, of different ages, to operate in relatively benign environmental areas. Keeping in mind that merchant ships are usually dry-docked every fifth year for inspection, maintenance and repair (IMR) tasks, they are designed according to a more relaxed safety criteria compared to those normally applied for permanent offshore structures, in which the required IMR activities need to be carried out in-situ as they cannot be easily dry-docked. Moreover, ocean on-going ships may in principle avoid heavy weather conditions, whereas FPSOs are moored to a fixed location and could be exposed to harsher extreme conditions. Additionally, FPSOs are exposed to continuously varying still-water load effects, due to the permanent loading-off loading operations. These fundamental differences are even more important to recognize as most of the existing FPSOs around the globe are built based on converted hulls of oil tankers that have already operated during some years. This issue is particularly relevant for vessels whose service life need to be extended, as the deteriorating agents such as fatigue cracking and corrosion become more important. During the initial design of ship structures, the effects of fatigue and corrosion are accounted for separately. However, as the structure ages, the interaction between these two degrading agents increases, and thus such an interaction needs to be accounted for. Moreover, as the number of cracks in a hull structure increases with time, the likelihood of fracture occurrence in main structural

Lifting simulation of an offshore supply vessel considering various operating conditions

Directory of Open Access Journals (Sweden)

Dong-Hoon Jeong

2016-06-01

Full Text Available Recently, an offshore support vessel is being widely used to install an offshore structure such as a subsea equipment which is laid on its deck. The lifting operation which is one of the installation operations includes lifting off, lifting in the air, splash zone crossing, deep submerging, and finally landing of the structure with an offshore support vessel crane. There are some major considerations during this operation. Especially, when lifting off the structure, if operating conditions such as ocean environmental loads and hoisting (or lowering speed are bad, the excess of tension of wire ropes of the crane and the collision between the offshore support vessel and the structure can be occurred due to the relative motion between them. To solve this problem, this study performs the lifting simulation while the offshore support vessel installs the structure. The simulation includes the calculation of dynamic responses of the offshore support vessel and the equipment, including the wire tension and the collision detection. To check the applicability of the simulation, it is applied to some lifting steps by varying operating conditions. As a result, it is confirmed that the conditions affect the operability of those steps.

Healthy offshore workforce? A qualitative study on offshore wind employees' occupational strain, health, and coping.

Science.gov (United States)

Mette, Janika; Velasco Garrido, Marcial; Harth, Volker; Preisser, Alexandra M; Mache, Stefanie

2018-01-23

Offshore work has been described as demanding and stressful. Despite this, evidence regarding the occupational strain, health, and coping behaviors of workers in the growing offshore wind industry in Germany is still limited. The purpose of our study was to explore offshore wind employees' perceptions of occupational strain and health, and to investigate their strategies for dealing with the demands of offshore work. We conducted 21 semi-structured telephone interviews with employees in the German offshore wind industry. The interviews were transcribed and analyzed in a deductive-inductive approach following Mayring's qualitative content analysis. Workers generally reported good mental and physical health. However, they also stated perceptions of stress at work, fatigue, difficulties detaching from work, and sleeping problems, all to varying extents. In addition, physical health impairment in relation to offshore work, e.g. musculoskeletal and gastrointestinal complaints, was documented. Employees described different strategies for coping with their job demands. The strategies comprised of both problem and emotion-focused approaches, and were classified as either work-related, health-related, or related to seeking social support. Our study is the first to investigate the occupational strain, health, and coping of workers in the expanding German offshore wind industry. The results offer new insights that can be utilized for future research in this field. In terms of practical implications, the findings suggest that measures should be carried out aimed at reducing occupational strain and health impairment among offshore wind workers. In addition, interventions should be initiated that foster offshore wind workers' health and empower them to further expand on effective coping strategies at their workplace.

Visual analysis of uncertainties in ocean forecasts for planning and operation of off-shore structures

KAUST Repository

Hollt, Thomas; Magdy, Ahmed; Chen, Guoning; Gopalakrishnan, Ganesh; Hoteit, Ibrahim; Hansen, Charles D.; Hadwiger, Markus

2013-01-01

We present a novel integrated visualization system that enables interactive visual analysis of ensemble simulations used in ocean forecasting, i.e, simulations of sea surface elevation. Our system enables the interactive planning of both the placement and operation of off-shore structures. We illustrate this using a real-world simulation of the Gulf of Mexico. Off-shore structures, such as those used for oil exploration, are vulnerable to hazards caused by strong loop currents. The oil and gas industry therefore relies on accurate ocean forecasting systems for planning their operations. Nowadays, these forecasts are based on multiple spatio-temporal simulations resulting in multidimensional, multivariate and multivalued data, so-called ensemble data. Changes in sea surface elevation are a good indicator for the movement of loop current eddies, and our visualization approach enables their interactive exploration and analysis. We enable analysis of the spatial domain, for planning the placement of structures, as well as detailed exploration of the temporal evolution at any chosen position, for the prediction of critical ocean states that require the shutdown of rig operations. © 2013 IEEE.

Visual analysis of uncertainties in ocean forecasts for planning and operation of off-shore structures

KAUST Repository

Hollt, Thomas

2013-02-01

We present a novel integrated visualization system that enables interactive visual analysis of ensemble simulations used in ocean forecasting, i.e, simulations of sea surface elevation. Our system enables the interactive planning of both the placement and operation of off-shore structures. We illustrate this using a real-world simulation of the Gulf of Mexico. Off-shore structures, such as those used for oil exploration, are vulnerable to hazards caused by strong loop currents. The oil and gas industry therefore relies on accurate ocean forecasting systems for planning their operations. Nowadays, these forecasts are based on multiple spatio-temporal simulations resulting in multidimensional, multivariate and multivalued data, so-called ensemble data. Changes in sea surface elevation are a good indicator for the movement of loop current eddies, and our visualization approach enables their interactive exploration and analysis. We enable analysis of the spatial domain, for planning the placement of structures, as well as detailed exploration of the temporal evolution at any chosen position, for the prediction of critical ocean states that require the shutdown of rig operations. © 2013 IEEE.

Reduced-order model for inertial locomotion of a slender swimmer

Science.gov (United States)

Mahalinkam, Raksha; Gong, Felicity; Khair, Aditya S.

2018-04-01

The inertial locomotion of an elongated model swimmer in a Newtonian fluid is quantified, wherein self-propulsion is achieved via steady tangential surface treadmilling. The swimmer has a length 2 l and a circular cross section of longitudinal profile a R (z ) , where a is the characteristic width of the cross section, R (z ) is a dimensionless shape function, and z is a dimensionless coordinate, normalized by l , along the centerline of the body. It is assumed that the swimmer is slender, ɛ =a /l ≪1 . Hence, we utilize slender-body theory to analyze the Navier-Stokes equations that describe the flow around the swimmer. Therefrom, we compute an asymptotic approximation to the swimming speed, U , as U /us=1 -β [V (Re ) -1/2 ∫-11z lnR (z ) d z ] /ln(1 /ɛ ) +O [1 /ln2(1 /ɛ ) ], where us is the characteristic speed of the surface treadmilling, Re is the Reynolds number based on the body length, and β is a dimensionless parameter that differentiates between "pusher" (propelled from the rear, β 0 ) -type swimmers. The function V (Re ) increases monotonically with increasing Re ; hence, fluid inertia causes an increase (decrease) in the swimming speed of a pusher (puller). Next, we demonstrate that the power expenditure of the swimmer increases monotonically with increasing Re . Further, the power expenditures of a puller and pusher with the same value of |β | are equal. Therefore, pushers are superior in inertial locomotion as compared to pullers, in that they achieve a faster swimming speed for the same power expended. Finally, it is demonstrated that the flow structure predicted from our reduced-order model is consistent with that from direct numerical simulation of swimmers at intermediate Re .

Rigid Finite Element Method in Analysis of Dynamics of Offshore Structures

CERN Document Server

Wittbrodt, Edmund; Maczyński, Andrzej; Wojciech, Stanisław

2013-01-01

This book describes new methods developed for modelling dynamics of machines commonly used in the offshore industry. These methods are based both on the rigid finite element method, used for the description of link deformations, and on homogeneous transformations and joint coordinates, which is applied to the modelling of multibody system dynamics. In this monograph, the bases of the rigid finite element method  and homogeneous transformations are introduced. Selected models for modelling dynamics of offshore devices are then verified both by using commercial software, based on the finite element method, as well as by using additional methods. Examples of mathematical models of offshore machines, such as a gantry crane for Blowout-Preventer (BOP) valve block transportation, a pedestal crane with shock absorber, and pipe laying machinery are presented. Selected problems of control in offshore machinery as well as dynamic optimization in device control are also discussed. Additionally, numerical simulations of...

A Coupled VOF-Eulerian Multiphase CFD Model to Simulate Breaking Wave Impacts on Offshore Structures

DEFF Research Database (Denmark)

Tomaselli, Pietro; Christensen, Erik Damgaard

2016-01-01

Breaking wave-induced loads on offshore structures can be extremely severe. The air entrainment mechanism during the breaking process plays a not well-known role in the exerted forces. This paper present a CFD solver, developed in the Open-FOAM environment, capable of simulating the wave breaking...

Offshore Wind Turbine Design

DEFF Research Database (Denmark)

Frandsen, Sten; Hansen, Erik Asp; Ibsen, Lars Bo

2006-01-01

Current offshore wind turbine design methods have matured to a 1st generation state, manifested in the draft of a possible standard, IEC 61400-3 (2005). It is now time to investigate the possibilities of improving existing methods. To do so in an efficient manner a clear identification of the most...... important uncertainty drivers specific for offshore wind turbine design loads is required. Describing the initial efforts in a Danish research project, the paper points to focal points for research and development. These are mainly: soil-structure interaction, improved modelling of wave loads from deep...

Dynamic Properties of Offshore Wind Turbine Foundations

DEFF Research Database (Denmark)

Damgaard, Mads

ages structurally over its service life. Well-covered in the field of earthquake engineering, the dynamic response of civil engineering structures is highly dependent on the impedance of the soil–foundation system. For offshore wind turbine applications, however, the hysteretical and geometrical......, there is a general consensus that offshore wind-generated electricity is still too expensive to be competitive with conventional energy sources. As a consequence, the overall weight of the turbine and foundation is kept to a minimum resulting in a flexible and dynamically active structural system—even at low...

Final report WP 4.2 : Support Structure Concepts for Deep Water Sites: Deliverable D4.2.8 (WP4: offshore foundations and support structures)

NARCIS (Netherlands)

De Vries, W.E.; Vemula, N.K.; Passon, P.; Fischer, T.; Kaufer, D.; Matha, D.; Schmidt, B.; Vorpahl, F.

2011-01-01

With the number of offshore wind farms rapidly increasing, in a wide variety of site conditions and using different turbine sizes, the need for alternative support structures other than the conventional monopile structure is apparent and several projects have been realised using other support

Accessing offshoring advantages

DEFF Research Database (Denmark)

Mykhaylenko, Alona; Motika, Agnes; Wæhrens, Brian Vejrum

2015-01-01

. Assuming that different levels of synergy may exist between particular offshoring strategic decisions (choosing offshore outsourcing or captive offshoring and the type of function) and different offshoring advantages, this work advocates that the actual fact of realization of certain offshoring advantages...

An Introduction to Operational Modal Identification of Offshore Wind Turbine Structures

DEFF Research Database (Denmark)

Damgaard, Mads

excitation originating from the rotating rotor and broadband excitation from air turbulence is present, which sets limitations on the applicability of operational modal analysis to wind turbine structures. The technical memorandum contains an introduction to the theory within experimental modal analysis and......The present technical memorandum “An Introduction to Operational Modal Identification of Offshore Wind Turbine Structures” is prepared in connection with an ongoing Ph.D study at Aalborg University. The memorandum is intended for use in the civil engineering field and may serve as an inspiration...

Rigid finite element method in analysis of dynamics of offshore structures

Energy Technology Data Exchange (ETDEWEB)

Wittbrodt, Edmund [Gdansk Univ. of Technology (Poland); Szczotka, Marek; Maczynski, Andrzej; Wojciech, Stanislaw [Bielsko-Biala Univ. (Poland)

2013-07-01

This book describes new methods developed for modelling dynamics of machines commonly used in the offshore industry. These methods are based both on the rigid finite element method, used for the description of link deformations, and on homogeneous transformations and joint coordinates, which is applied to the modelling of multibody system dynamics. In this monograph, the bases of the rigid finite element method and homogeneous transformations are introduced. Selected models for modelling dynamics of offshore devices are then verified both by using commercial software, based on the finite element method, as well as by using additional methods. Examples of mathematical models of offshore machines, such as a gantry crane for Blowout-Preventer (BOP) valve block transportation, a pedestal crane with shock absorber, and pipe laying machinery are presented. Selected problems of control in offshore machinery as well as dynamic optimization in device control are also discussed. Additionally, numerical simulations of pipe-laying operations taking active reel drive into account are shown.

Breaking wave impact on offshore tripod structures. Comparison of large scale experiments, CFD simulations, and DIN recommended practice; Wellenbrechen an Offshore Tripod-Gruendungen. Versuche und Simulationen im Vergleich zu Richtlinien

Energy Technology Data Exchange (ETDEWEB)

Hildebrandt, Arndt; Schlurmann, Torsten [Hannover Univ. (Germany). Franzius-Institut fuer Wasserbau und Kuesteningenieurwesen

2012-05-15

Coastal and near shore areas offer a large potential for offshore wind energy production due to strong and steady wind conditions. Thousands of offshore wind energy converters are projected for mass production within the next years. Detailed understanding of the extreme, dynamic wave loads on offshore structures is essential for an efficient design. The impact on structures is a complex process and further studies are required for more detailed load assessments, which is why breaking wave loads were investigated by the research project ''GIGAWIND alpha ventus - Subproject 1'' within the network ''Research at Alpha VEntus'' (RAVE). Large scale laboratory tests (1:12) with breaking waves have been carried out at the Large Wave Flume of the ''Forschungszentrum Kueste'' (FZK, Hanover) to reveal more detailed insights on the impact area, duration and development of the wave induced momentum, and intensity of pressures. In addition, local pressures calculated by a three-dimensional numerical impact simulation are compared to the Large Wave Flume experiments. Slamming coefficients have been derived from the physical model tests and CFD simulations for the comparison to load calculations based on guidelines. (orig.)

Reliability-Based Planning of Inspection, Operation and Maintenance for Offshore Oil & Gas Structures and Wind Turbines

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard

2011-01-01

Reliability-based cost-optimal planning of inspection, maintenance and operation has many applications. In this paper applications for planning of inspections for oil & gas jacket structures and of operation and maintenance of offshore wind turbines are described and illustrated by examples....

Nonlinear behavior of nuclear buildings made of low slenderness ratio under alternate loading. Vol. 1

International Nuclear Information System (INIS)

Assadi, Said.

1985-04-01

Outside horizontal forces shells of a nuclear building are subjected to traction or compression vertical forces on the horizontal cross section, they are indeed gravity forces (compression) or vertical component of seismic sollicitation (traction). These shells, generally twice more reinforced than ordinary buildings, have a slenderness ratio rarely above 1. Role of shearing stress is more important than flexion. As a result, horizontal reinforcements of low slenderness ratio loose their efficiency in shear resistance, however in some case local resistance to shear is secured. Flexure resistance is obtained by armouring in vertical edges. Resistance, ductility damping and rigidity of plane shells are studied under the action of repeated alternate horizontal forces with or without a perpendicular traction (or compression) force. A computer code CADBANU was realized to study the response of nuclear building made of low slenderness ratio under a dynamic excitation applied to the base. This program gives the horizontal translation and rotation for each floor. The first version of this program was verified and graphic results are given [fr

Slender Ca ii H Fibrils Mapping Magnetic Fields in the Low Solar Chromosphere

Energy Technology Data Exchange (ETDEWEB)

Jafarzadeh, S.; Rutten, R. J.; Szydlarski, M. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway); Solanki, S. K.; Wiegelmann, T.; Riethmüller, T. L.; Noort, M. van; Barthol, P.; Gandorfer, A.; Gizon, L.; Hirzberger, J. [Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany); Rodríguez, J. Blanco [Grupo de Astronomía y Ciencias del Espacio, Universidad de Valencia, E-46980 Paterna, Valencia (Spain); Iniesta, J. C. del Toro; Suárez, D. Orozco [Instituto de Astrofísica de Andalucía (CSIC), Apartado de Correos 3004, E-18080 Granada (Spain); Knölker, M. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Pillet, V. Martínez [National Solar Observatory, 3665 Discovery Drive, Boulder, CO 80303 (United States); Schmidt, W., E-mail: shahin.jafarzadeh@astro.uio.no [Kiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, D-79104 Freiburg (Germany)

2017-04-01

A dense forest of slender bright fibrils near a small solar active region is seen in high-quality narrowband Ca ii H images from the SuFI instrument onboard the Sunrise balloon-borne solar observatory. The orientation of these slender Ca ii H fibrils (SCF) overlaps with the magnetic field configuration in the low solar chromosphere derived by magnetostatic extrapolation of the photospheric field observed with Sunrise/IMaX and SDO/HMI. In addition, many observed SCFs are qualitatively aligned with small-scale loops computed from a novel inversion approach based on best-fit numerical MHD simulation. Such loops are organized in canopy-like arches over quiet areas that differ in height depending on the field strength near their roots.

Co-sourcing in software development offshoring

DEFF Research Database (Denmark)

Schlichter, Bjarne Rerup; Persson, John Stouby

2013-01-01

Software development projects are increasingly geographical distributed with offshoring, which introduce complex risks that can lead to project failure. Co-sourcing is a highly integrative and cohesive approach, seen successful, to software development offshoring. However, research of how co-sour......-taking by high attention to of the closely interrelated structure and technology components in terms of CMMI and the actors’ cohesion and integration in terms of Scrum....

Corrosion Protection Systems and Fatigue Corrosion in Offshore Wind Structures: Current Status and Future Perspectives

Directory of Open Access Journals (Sweden)

Seth J. Price

2017-02-01

Full Text Available Concerns over reducing CO2 emissions associated with the burning of fossil fuels in combination with an increase in worldwide energy demands is leading to increased development of renewable energies such as wind. The installation of offshore wind power structures (OWS is one of the most promising approaches for the production of renewable energy. However, corrosion and fatigue damage in marine and offshore environments are major causes of primary steel strength degradation in OWS. Corrosion can reduce the thickness of structural components which may lead towards fatigue crack initiation and buckling. These failure mechanisms affect tower service life and may result in catastrophic structural failure. Additionally, environmental pollution stemming from corrosion’s by-products is possible. As a result, large financial investments are made yearly for both the prevention and recovery of these drawbacks. The corrosion rate of an OWS is dependent on different characteristics of attack which are influenced by access to oxygen and humidity. Structural degradation can occur due to chemical attack, abrasive action of waves, and microorganism attacks. Inspired by technological and scientific advances in recent years, the purpose of this paper is to discuss the current protective coating system technologies used to protect OWS as well as future perspectives.

Legal aspects of financing Canadian offshore oil and gas developments

International Nuclear Information System (INIS)

Green, J.M.; Hudec, A.J.

1992-01-01

A review is presented of the significant legal considerations involved in structuring, negotiating, and documenting commercial financing of a Canadian offshore oil and gas production facility. Emphasis is placed on the Hibernia Project in the Newfoundland offshore as an example, and more specifically the $450 million bank financing completed in November 1991. The legal framework governing offshore production financing in this case was complex, due to the project's location in international waters on the continental shelf. Complex intergovernmental arrangements have been implemented between Canada and Newfoundland to govern the offshore area and regulate the project. An agreement called the Atlantic Accord allowed the Canada Newfoundland Offshore Petroleum Board (CNOPB) to grant production licenses and to regulate offshore exploration and development, with matters relating to legislation, taxation, and royalties shared between the governments. Certain other acts were enacted or extended for application to the offshore area. The CNOPB administers a registry system for transfers and security interests in offshore licenses. Security interests including property are ensured by the Hibernia Act, which makes Newfoundland's existing security interest regime applicable to the offshore. The project owners are operating Hibernia as a joint venture, and the structure of project financing and inter-creditor arrangements is examined. The competing security interest of project lenders and non-defaulting participants is discussed, along with assignment of priorities on the security in case of default

Prospects of the French offshore wind power market

International Nuclear Information System (INIS)

Anon.

2011-12-01

This market study about the French offshore wind power industry presents: 1 - the bases of the offshore wind power market: wind turbine operation principle, foundations and scale change; 2 - business model of offshore wind power projects: logistical, technical and financial challenges, cost structure and profitability of projects (investment, power generation costs, incentive mechanisms), project development time; 3 - European and French regulatory framework: the energy/climate package, the French 'Grenelle de l'Environnement' commitments for the development of renewable energies; 4 - start up of the French offshore wind power market: the onshore wind power market looking for growth relaying, the lateness of the offshore market, outlines of the call for bids and of the first phase launching (schedule, selected sites and candidates), market development stakes and opportunities; 5 - offshore wind power overview in Europe - lessons for the French market prospects: status of the European market (installed power/country, projects in progress), European leaders of the market (analysis of the British, Danish and German markets successful takeoff), specificities of the French market (are all favourable conditions present?); 6 - takeoff of the French market - what opportunities on the overall value chain?: front-end of the industry (manufacturers and component suppliers: industry structure, competition, R and D, subcontractors in France), back-end of the industry (developers/operators: sector analysis, ambitions, alliances, competences), specific French know-how in offshore installation and connection of wind turbines (reconversion of harbour areas, re-positioning of shipbuilding industry). (J.S.)

High speed forging of solid powder discs of large slenderness ratio

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

Slenderness ratio; preform; interfacial friction law. 1. ... Interfacial friction law. Friction condition between deforming tool and work piece in metal forming are of the greatest importance concerning a number of factors such as force and mode of deformation, proper- ... The velocity field for the case under consideration is.

Development of Seismic Demand for Chang-Bin Offshore Wind Farm in Taiwan Strait

Directory of Open Access Journals (Sweden)

Yu-Kai Wang

2016-12-01

Full Text Available Taiwan is located on the Pacific seismic belt, and the soil conditions of Taiwan’s offshore wind farms are softer than those in Europe. To ensure safety and stability of the offshore wind turbine supporting structures, it is important to assess the offshore wind farms seismic forces reasonably. In this paper, the relevant seismic and geological data are obtained for Chang-Bin offshore wind farm in Taiwan Strait, the probabilistic seismic hazard analysis (PSHA is carried out, and the first uniform hazard response spectrum for Chang-Bin offshore wind farm is achieved. Compared with existing design response spectrum in the local regulation, this site-specific seismic hazard analysis has influence on the seismic force considered in the design of supporting structures and therefore affects the cost of the supporting structures. The results show that a site-specific seismic hazard analysis is required for high seismic area. The paper highlights the importance of seismic hazard analysis to assess the offshore wind farms seismic forces. The follow-up recommendations and research directions are given for Taiwan’s offshore wind turbine supporting structures under seismic force considerations.

Application of an engineering inviscid-boundary layer method to slender three-dimensional vehicle forebodies

Science.gov (United States)

Riley, Christopher J.

1993-01-01

An engineering inviscid-boundary layer method has been modified for application to slender three-dimensional (3-D) forebodies which are characteristic of transatmospheric vehicles. An improved shock description in the nose region has been added to the inviscid technique which allows the calculation of a wider range of body geometries. The modified engineering method is applied to the perfect gas solution over a slender 3-D configuration at angle of attack. The method predicts surface pressures and laminar heating rates on the windward side of the vehicle that compare favorably with numerical solutions of the thin-layer Navier-Stokes equations. These improvements extend the 3-D capabilities of the engineering method and significantly increase its design applications.

Offshore petroleum engineering task force report

International Nuclear Information System (INIS)

Ruelokke, M.

1999-05-01

The Offshore Petroleum Engineering Task Force was established in July 1998 in response to concerns about Newfoundland and Labrador's share of offshore petroleum engineering activity, with the aim of determining the current capability of the local sector, the demand for such companies and individuals until the year 2010, their capability to grow over that time-frame, and requirements in order to achieve that growth. The report summarizes the analysis undertaken by the Task Force as well as the conclusions it reached and associated recommendations. Section two provides an overview of the offshore engineering activity, including its origins, structure, and key success factors, and its also provides a profile of the industry, internationally, in Canada and in Newfoundland. Section three presents an analysis of the future demand for offshore engineering in Newfoundland until 2010, based on three development scenarios. Section four based on a Consulting Engineers of Newfoundland and Labrador (CENL) survey, establishes the present offshore engineering capacity and capabilities within the province. Section five examines current education and training programs and their ability to respond to future demands. Section six summarizes the conclusions of the analysis and presents recommendations designed to facilitate and promote the development of the local offshore engineering industry. 6 figs

Analysis of Tide and Offshore Storm-Induced Water Table Fluctuations for Structural Characterization of a Coastal Island Aquifer

Science.gov (United States)

Trglavcnik, Victoria; Morrow, Dean; Weber, Kela P.; Li, Ling; Robinson, Clare E.

2018-04-01

Analysis of water table fluctuations can provide important insight into the hydraulic properties and structure of a coastal aquifer system including the connectivity between the aquifer and ocean. This study presents an improved approach for characterizing a permeable heterogeneous coastal aquifer system through analysis of the propagation of the tidal signal, as well as offshore storm pulse signals through a coastal aquifer. Offshore storms produce high wave activity, but are not necessarily linked to significant onshore precipitation. In this study, we focused on offshore storm events during which no onshore precipitation occurred. Extensive groundwater level data collected on a sand barrier island (Sable Island, NS, Canada) show nonuniform discontinuous propagation of the tide and offshore storm pulse signals through the aquifer with isolated inland areas showing enhanced response to both oceanic forcing signals. Propagation analysis suggests that isolated inland water table fluctuations may be caused by localized leakage from a confined aquifer that is connected to the ocean offshore but within the wave setup zone. Two-dimensional groundwater flow simulations were conducted to test the leaky confined-unconfined aquifer conceptualization and to identify the effect of key parameters on tidal signal propagation in leaky confined-unconfined coastal aquifers. This study illustrates that analysis of offshore storm signal propagation, in addition to tidal signal propagation, provides a valuable and low resource approach for large-scale characterization of permeable heterogeneous coastal aquifers. Such an approach is needed for the effective management of coastal environments where water resources are threatened by human activities and the changing climate.

IS OFFSHORING AN INTERNATIONAL PROCESS

Directory of Open Access Journals (Sweden)

Paulo Roberto Gião

2012-01-01

Full Text Available This article proposes to analyze the applicability of transaction cost economics - TCE (Coase, 1937; Williamson, 1975, 1979 through its characteristic make-or-buy expression, considering the offshoring pace and emerging economy firms. The make-or-buy decision must be flexible enough to explain offshoring characteristics and developed and emerging economy firms scenarios. As secondary objectives, and to show the trail to the main purpose, two research questions were identified and discussed during the paper: Is offshoring process an international movement only from developed countries to emerging economies? Is the main reason of offshoring the looking for low-cost work / activities? To achieve the proposed objectives, the structure of this paper begins with a reasonable or acceptable definition of offshoring. Some reasons (or “the reason” for the process are also another important starting point. The majority of articles referee the idea that low-cost is the main reason for offshoring, and if it is correct, transaction cost economics seems to be a good basis for our analysis purpose and integrative intention. Also some literature connections between offshoring and TCE are presented and, naturally TCE is presented in highlights for understanding these connections. Ending this section, some different arguments based on newer researches are presented by some authors presenting another perspective as the main reason. After this theoretical approach, a scenario analysis and some discussions are presented based on all possible interactions among firm from developed (DC and emerging economies (EE and examples of international corporations are presented to clarify and improve the understanding of our research questions and to build new contributions to international business theory.

Risks to offshore installations in Europe due to natural hazards

Science.gov (United States)

Necci, Amos; Krausmann, Elisabeth

2017-04-01

Natural hazards, such as storms, earthquakes, or lightning are a major threat to industry. In particular, chemical plants, storage facilities, pipelines, and offshore oil and gas facilities are vulnerable to natural events which can cause hazardous materials releases and thereby endanger workers, the population and the environment. These technological accidents are commonly referred to as Natech accidents. Recent events have increased concerns about safety in the offshore oil and gas sector, and the need for improving knowledge on the matter has become evident. With those premises, we analyzed accidents, near misses and accident precursors at offshore facilities in Europe caused by natural events using both a statistical and a qualitative approach. For this purpose, we screened the World Offshore Accident Database (WOAD) to identify all incidents that featured natural events as causes or aggravating factors. A dataset of 1,085 global Natech events was built for the statistical analysis. Among those, a subset composed of 303 European records was selected. The results of the analysis showed that offshore Natech events in Europe are frequent; they resulted, however, in low consequences. The main threat to offshore facilities resulted from bad weather, such as strong winds and heavy seas. Storms can put intense loads on the structural parts of offshore installations, eventually exceeding design resistance specifications. Several incidents triggered by lightning strikes and earthquakes were also recorded. Substantial differences in terms of vulnerability, damage modality and consequences emerged between fixed and floating offshore structures. The main damage mode for floating structures was the failure of station keeping systems due to the rupture of mooring or anchors, mainly caused by adverse meteorological conditions. Most of the incidents at fixed offshore structures in Europe involved falling loads for both metal jacket and concrete base platforms due to storms. In

Hypersonic flow past slender bodies in dispersive hydrodynamics

International Nuclear Information System (INIS)

El, G.A.; Khodorovskii, V.V.; Tyurina, A.V.

2004-01-01

The problem of two-dimensional steady hypersonic flow past a slender body is formulated for dispersive media. It is shown that for the hypersonic flow, the original 2+0 boundary-value problem is asymptotically equivalent to the 1+1 piston problem for the fully nonlinear flow in the same physical system, which allows one to take advantage of the analytic methods developed for one-dimensional systems. This type of equivalence, well known in ideal Euler gas dynamics, has not been established for dispersive hydrodynamics so far. Two examples pertaining to collisionless plasma dynamics are considered

Control of Flow Structure on Non-Slender Delta Wing: Bio-inspired Edge Modifications, Passive Bleeding, and Pulsed Blowing

Science.gov (United States)

Yavuz, Mehmet Metin; Celik, Alper; Cetin, Cenk

2016-11-01

In the present study, different flow control approaches including bio-inspired edge modifications, passive bleeding, and pulsed blowing are introduced and applied for the flow over non-slender delta wing. Experiments are conducted in a low speed wind tunnel for a 45 degree swept delta wing using qualitative and quantitative measurement techniques including laser illuminated smoke visualization, particle image velocimety (PIV), and surface pressure measurements. For the bio-inspired edge modifications, the edges of the wing are modified to dolphin fluke geometry. In addition, the concept of flexion ratio, a ratio depending on the flexible length of animal propulsors such as wings, is introduced. For passive bleeding, directing the free stream air from the pressure side of the planform to the suction side of the wing is applied. For pulsed blowing, periodic air injection through the leading edge of the wing is performed in a square waveform with 25% duty cycle at different excitation frequencies and compared with the steady and no blowing cases. The results indicate that each control approach is quite effective in terms of altering the overall flow structure on the planform. However, the success level, considering the elimination of stall or delaying the vortex breakdown, depends on the parameters in each method.

Impulse Based Substructuring for Coupling Offshore Structures and Wind Turbines in Aero-Elastic Simulations

NARCIS (Netherlands)

Van der Valk, P.L.C.; Rixen, D.J.

2012-01-01

In order to achieve the goal of 20% renewable energy in 2020, as set by the European Union, large offshore wind farms are either under construction or in development through-out Europe. As many of the "easy" locations are already under development, offshore wind farms are moving further offshore

Integration of Wave and Offshore Wind Energy in a European Offshore Grid

DEFF Research Database (Denmark)

Chozas, Julia Fernandez; Sørensen, H. C.; Korpås, M.

2010-01-01

of offshore renewable energy sources. According to this, the paper covers i) public and private initiatives for offshore transmission networks, ii) the synergies between the wave and the offshore wind energy sector within an offshore grid, iii) power transmission options for offshore generation and iv...

Fatal infection in three Grey Slender Lorises (Loris lydekkerianus nordicus) caused by clonally related Trueperella pyogenes.

Science.gov (United States)

Nagib, Samy; Glaeser, Stefanie P; Eisenberg, Tobias; Sammra, Osama; Lämmler, Christoph; Kämpfer, Peter; Schauerte, Nicole; Geiger, Christina; Kaim, Ute; Prenger-Berninghoff, Ellen; Becker, André; Abdulmawjood, Amir

2017-08-29

Trueperella pyogenes is a worldwide known bacterium causing mastitis, abortion and various other pyogenic infections in domestic animals like ruminants and pigs. In this study we represent the first case report of three unusual fatal infections of Grey Slender Lorises caused by Trueperella pyogenes. Meanwhile, this study represents the first in-depth description of the multilocus sequence analysis (MLSA) on T. pyogenes species. Three Trueperella pyogenes were isolated from three different Grey Slender Lorises, which died within a period of two years at Frankfurt Zoo (Frankfurt am Main - Germany). The three Grey Slender Loris cases were suffering from severe sepsis and died from its complication. During the bacteriological investigation of the three cases, the T. pyogenes were isolated from different organisms in each case. The epidemiological relationship between the three isolates could be shown by four genomic DNA fingerprint methods (ERIC-PCR, BOX-PCR, (GTG) 5 -PCR, and RAPD-PCR) and by multilocus sequence analysis (MLSA) investigating four different housekeeping genes (fusA-tuf-metG-gyrA). In this study, we clearly showed by means of using three different rep-PCRs, by RAPD-PCR and by MLSA that the genomic fingerprinting of the investigated three T. pyogenes have the same clonal origin and are genetically identical. These results suggest that the same isolate contaminated the animal's facility and subsequently caused cross infection between the three different Grey Slender Lorises. To the best of our knowledge, this is the first epidemiological approach concentrating on T. pyogenes using MLSA.

Optimal Risk-Based Inspection Planning for Offshore Wind Turbines

DEFF Research Database (Denmark)

Rangel-Ramirez, Jose G.; Sørensen, John Dalsgaard

2008-01-01

, inspection and maintenance activities are developed. This paper considers aspects of inspection and maintenance planning of fatigue prone details in jacket and tripod types of wind turbine support structures. Based oil risk-based inspection planning methods used for oil & gas installations, a framework......Wind turbines for electricity production have increased significantly the last years both in production capability and size. This development is expected to continue also in the coining years. The Support structure for offshore wind turbines is typically a steel structure consisting of a tower...... for optimal inspection and maintenance planning of offshore wind turbines is presented. Special aspects for offshore wind turbines are considered: usually the wind loading are dominating the wave loading, wake effects in wind farms are important and the reliability level is typically significantly lower than...

Strength Analysis of a Large-Size Supporting Structure for an Offshore Wind Turbine

Directory of Open Access Journals (Sweden)

Niklas Karol

2017-04-01

Full Text Available The offshore wind power industry is the branch of electric energy production from renewable sources which is most intensively developed in EU countries. At present, there is a tendency to install larger-power wind turbines at larger distances from the seashore, on relatively deep waters. Consequently, technological solutions for new supporting structures intended for deeper water regions are undergoing rapid development now. Various design types are proposed and analysed, starting from gravitational supports (GBS, through monopiles and 3D frame structures (jackets, tripods, and ending with floating and submerged supports anchored to the seabed by flexible connectors, including TLP type solutions.

Integrity management of offshore structures and its implication on computation of structural action effects and resistance

Science.gov (United States)

Moan, T.

2017-12-01

An overview of integrity management of offshore structures, with emphasis on the oil and gas energy sector, is given. Based on relevant accident experiences and means to control the associated risks, accidents are categorized from a technical-physical as well as human and organizational point of view. Structural risk relates to extreme actions as well as structural degradation. Risk mitigation measures, including adequate design criteria, inspection, repair and maintenance as well as quality assurance and control of engineering processes, are briefly outlined. The current status of risk and reliability methodology to aid decisions in the integrity management is briefly reviewed. Finally, the need to balance the uncertainties in data, methods and computational efforts and the cautious use and quality assurance and control in applying high fidelity methods to avoid human errors, is emphasized, and with a plea to develop both high fidelity as well as efficient, simplified methods for design.

Towards a mature offshore wind energy technology - guidelines from the opti-OWECS project

Science.gov (United States)

Kühn, M.; Bierbooms, W. A. A. M.; van Bussel, G. J. W.; Cockerill, T. T.; Harrison, R.; Ferguson, M. C.; Göransson, B.; Harland, L. A.; Vugts, J. H.; Wiecherink, R.

1999-01-01

The article reviews the main results of the recent European research project Opti-OWECS (Structural and Economic Optimisation of Bottom-Mounted Offshore Wind Energy Converters'), which has significantly improved the understanding of the requirements for a large-scale utilization of offshore wind energy. An integrated design approach was demonstrated for a 300 MW offshore wind farm at a demanding North Sea site. Several viable solutions were obtained and one was elaborated to include the design of all major components. Simultaneous structural and economic optimization took place during the different design stages. An offshore wind energy converter founded on a soft-soft monopile was tailored with respect to the distinct characteristics of dynamic wind and wave loading. The operation and maintenance behaviour of the wind farm was analysed by Monte Carlo simulations. With an optimized maintenance strategy and suitable hardware a high availability was achieved. Based upon the experience from the structural design, cost models for offshore wind farms were developed and linked to a European database of the offshore wind energy potential. This enabled the first consistent estimate of cost of offshore wind energy for entire European regions.

Les ouvrages pétroliers en mer Offshore Petroleum Structures

Directory of Open Access Journals (Sweden)

Susbielles G.

2006-11-01

the Cognac, Hondo, Ninian and Maureen fields are distinguished from the others by eithertheir architecture or their dimensions. Most of the concrete platforms are installed in the North Sea. The one on the Ninian field is largerthan all the others. An exceptionisBrazilwheretherearethreeplatforms in shallow water. For marginal fields or ta determine the exact characteristics of a discovered field, Mirr production is started up from subsea wellheads via a manifold and links ta a floating structure (semisubmersible platform, tanker. Few chang es have been made in semisubmersible platforms. Solely the Sedco709 platform is different from the others because it is dynamically positioned. The mort important offshore hoisting operations are done by very large capacity cranes. The designing of loading stations is done exclusively by a few companies. As for the laying of pipelines and pipes, it has evolved with the appearance of structures such as the Castoro VI barge of Saipem and the Apache barge of Santa Fe and the ship Flexservice I. Engineers still have the task of creating deep offshore development systems (water depth. greater than 500 m.

Simulation of Floaters in Action

DEFF Research Database (Denmark)

Nielsen, Morten Eggert; Ulriksen, Martin Dalgaard; Damkilde, Lars

This report is the first in a series of three, which altogether documents: 1. theory 2. numerical implementation 3. application for Simulation of Floaters in Action (SOFIA), which is a structural analysis tool for slender offshore structures, such as monopiles, jacket structures and floating space...... frame structures. The current report represents the theoretical basis, while the numerical implementation and application of SOFIA are documented in two individual reports. In relation to other structural analysis tools, the present tool allows for geometrical nonlinearities, which may be exhibited...

Aeroelastic impact of above-rated wave-induced structural motions on the near-wake stability of a floating offshore wind turbine rotor

Science.gov (United States)

Rodriguez, Steven; Jaworski, Justin

2017-11-01

The impact of above-rated wave-induced motions on the stability of floating offshore wind turbine near-wakes is studied numerically. The rotor near-wake is generated using a lifting-line free vortex wake method, which is strongly coupled to a finite element solver for kinematically nonlinear blade deformations. A synthetic time series of relatively high-amplitude/high-frequency representative of above-rated conditions of the NREL 5MW referece wind turbine is imposed on the rotor structure. To evaluate the impact of these above-rated conditions, a linear stability analysis is first performed on the near wake generated by a fixed-tower wind turbine configuration at above-rated inflow conditions. The platform motion is then introduced via synthetic time series, and a stability analysis is performed on the wake generated by the floating offshore wind turbine at the same above-rated inflow conditions. The stability trends (disturbance modes versus the divergence rate of vortex structures) of the two analyses are compared to identify the impact that above-rated wave-induced structural motions have on the stability of the floating offshore wind turbine wake.

Vertical Dynamic Stiffness of Offshore Foundations

DEFF Research Database (Denmark)

Latini, Chiara; Cisternino, Michele; Zania, Varvara

2016-01-01

Nowadays, pile and suction caisson foundations are widely used to support offshore structures which are subjected to vertical dynamic loads. The dynamic soil-structure interaction of floating foundations (foundations embedded in a soil layer whose height is greater than the foundation length) is ...

ISM Approach to Model Offshore Outsourcing Risks

OpenAIRE

Kumar, Sunand; Sharma, Rajiv Kumar; Chauhan, Prashant

2014-01-01

[EN] In an effort to achieve a competitive advantage via cost reductions and improved market responsiveness, organizations are increasingly employing offshore outsourcing as a major component of their supply chain strategies. But as evident from literature number of risks such as Political risk, Risk due to cultural differences, Compliance and regulatory risk, Opportunistic risk and Organization structural risk, which adversely affect the performance of offshore outsourcing in a supply chain ...

Fatigue Reliability of Offshore Wind Turbine Systems

DEFF Research Database (Denmark)

Marquez-Dominguez, Sergio; Sørensen, John Dalsgaard

2012-01-01

of appropriate partial safety factors / fatigue design factors (FDF) for steel substructures of offshore wind turbines (OWTs). The fatigue life is modeled by the SN approach. Design and limit state equations are established based on the accumulated fatigue damage. The acceptable reliability level for optimal...... fatigue design of OWTs is discussed and results for reliability assessment of typical fatigue critical design of offshore steel support structures are presented....

Moored offshore structures - evaluation of forces in elastic mooring lines

Science.gov (United States)

Crudu, L.; Obreja, D. C.; Marcu, O.

2016-08-01

In most situations, the high frequency motions of the floating structure induce important effects in the mooring lines which affect also the motions of the structure. The experience accumulated during systematic experimental tests and calculations, carried out for different moored floating structures, showed a complex influence of various parameters on the dynamic effects. Therefore, it was considered that a systematic investigation is necessary. Due to the complexity of hydrodynamics aspects of offshore structures behaviour, experimental tests are practically compulsory in order to be able to properly evaluate and then to validate their behaviour in real sea. Moreover the necessity to carry out hydrodynamic tests is often required by customers, classification societies and other regulatory bodies. Consequently, the correct simulation of physical properties of the complex scaled models becomes a very important issue. The paper is investigating such kind of problems identifying the possible simplification, generating different approaches. One of the bases of the evaluation has been found consideringtheresults of systematic experimental tests on the dynamic behaviour of a mooring chain reproduced at five different scales. Dynamic effects as well as the influences of the elasticity simulation for 5 different scales are evaluated together. The paper presents systematic diagrams and practical results for a typical moored floating structure operating as pipe layer based on motion evaluations and accelerations in waves.

Longitudinal acoustic instabilities in slender solid propellant rockets : linear analysis

OpenAIRE

García Schafer, Juan Esteban; Liñán Martínez, Amable

2001-01-01

To describe the acoustic instabilities in the combustion chambers of laterally burning solid propellant rockets the interaction of the mean flow with the acoustic waves is analysed, using multiple scale techniques, for realistic cases in which the combustion chamber is slender and the nozzle area is small compared with the cross-sectional area of the chamber. Associated with the longitudinal acoustic oscillations we find vorticity and entropy waves, with a wavelength typically small compared ...

Critical Factors Analysis for Offshore Software Development Success by Structural Equation Modeling

Science.gov (United States)

Wada, Yoshihisa; Tsuji, Hiroshi

In order to analyze the success/failure factors in offshore software development service by the structural equation modeling, this paper proposes to follow two approaches together; domain knowledge based heuristic analysis and factor analysis based rational analysis. The former works for generating and verifying of hypothesis to find factors and causalities. The latter works for verifying factors introduced by theory to build the model without heuristics. Following the proposed combined approaches for the responses from skilled project managers of the questionnaire, this paper found that the vendor property has high causality for the success compared to software property and project property.

Second wind in the offshore wind industry

International Nuclear Information System (INIS)

Philippe, Edouard; Neyme, Eric; Deboos, Christophe; Villageois, Jean-Remy; Gouverneur, Philippe; Gerard, Bernard; Fournier, Eric; Petrus, Raymond; Lemarquis, David; Dener, Marc; Bivaud, Jean-Pierre; Lemaire, Etienne; Nielsen, Steffen; Lafon, Xavier; Lagandre, Pierre; Nadai, Alain; Pinot de Villechenon, Edouard; Westhues, Markus; Herpers, Frederick; Bisiaux, Christophe; Sperlich, Miriam; Bales, Vincent; Vandenbroeck, Jan; His, Stephane; Derrey, Thierry; Barakat, Georges; Dakyo, Brayima; Carme, Laurent; Petit, Frederic; Ytournel, Sophie; Westhues, Markus; Diller, Armin; Premont, Antoine de; Ruer, Jacques; Lanoe, Frederic; Declercq, Jan; Holmager, Morten; Fidelin, Daniel; Guillet, Jerome; Dudziak, Gregory; Lapierre, Anne; Couturier, Ludovic; Audineau, Jean-Pierre; Rouaix, Eric; De Roeck, Yann-Herve; Quesnel, Louis; Duguet, Benjamin

2011-06-01

After several keynote addresses, this publication contains contributions and Power Point presentations proposed during this conference on the development of offshore wind energy. The successive sessions addressed the following issues: the offshore mass production of electricity (examples of Denmark and Belgium, laying and protecting offshore cables), the space, economic and environmental planning (the Danish experience, the role of the Coastal area integrated management, importance of the public debate, so on), the logistics of port infrastructures (simulation tools, example of Bremerhaven, issues related to project management), innovation at the core of industrial strategies (high power wind turbines, the 6 MW Alstom turbine, chain value and innovation in offshore wind energy, the Vertiwing innovating project of a floating wind turbine, a bench test in Charleston, foundations, gravity base structures, the British experience, the Danish experience), the economic and organisational conditions for development, the validation and certification of technologies

Optimised and balanced structural and system reliability of offshore wind turbines. An account

Energy Technology Data Exchange (ETDEWEB)

Tarp-Johansen, N.J.; Kozine, I. (Risoe National Lab., DTU, Roskilde, (DK)); Rademarkers, L. (Netherlands Energy Research Foundation (NL)); Dalsgaard Soerensen, J. (Aalborg Univ. (DK)) Ronold, K. (Det Norske Veritas (DK))

2005-04-15

This report gives the results of the research project 'Optimised and Uniform Safety and Reliability of Offshore Wind Turbines (an account)'. The main subject of the project has been the account of the state-of-the art of knowledge about, and/or attempts to, harmonisation of the structural reliability of wind turbines, on the one hand, and the reliability of the wind turbine's control/safety system, on the other hand. Within the project some research pointing ahead has also been conducted. (au)

Nonlinear Resonance Analysis of Slender Portal Frames under Base Excitation

Directory of Open Access Journals (Sweden)

Luis Fernando Paullo Muñoz

2017-01-01

Full Text Available The dynamic nonlinear response and stability of slender structures in the main resonance regions are a topic of importance in structural analysis. In complex problems, the determination of the response in the frequency domain indirectly obtained through analyses in time domain can lead to huge computational effort in large systems. In nonlinear cases, the response in the frequency domain becomes even more cumbersome because of the possibility of multiple solutions for certain forcing frequencies. Those solutions can be stable and unstable, in particular saddle-node bifurcation at the turning points along the resonance curves. In this work, an incremental technique for direct calculation of the nonlinear response in frequency domain of plane frames subjected to base excitation is proposed. The transformation of equations of motion to the frequency domain is made through the harmonic balance method in conjunction with the Galerkin method. The resulting system of nonlinear equations in terms of the modal amplitudes and forcing frequency is solved by the Newton-Raphson method together with an arc-length procedure to obtain the nonlinear resonance curves. Suitable examples are presented, and the influence of the frame geometric parameters and base motion on the nonlinear resonance curves is investigated.

Project alliancing in the offshore industry

International Nuclear Information System (INIS)

Halman, J.I.M.; Braks, B.F.M.

1999-01-01

In this paper the shift towards new types of project organisation within the offshore industry is explained and discussed. Special focus is given to the organisational concept of project alliancing. The principles, structure and culture of a project alliance as applied within the offshore industry are described. In the paper the organisational concept of project alliancing is discussed on its potential to reduce project costs and enhance profits, both for the operator (oil and gas company) as well as for participating contractors. A risk and reward mechanism developed to share project risks and rewards between allied parties is explained for an alliance case. Based upon an in-depth study carried out within a contractor company in the offshore industry the organisational and financial implications of project alliancing are presented. (author)

Occupational health offshore

Energy Technology Data Exchange (ETDEWEB)

Crosbie, A.; Davies, F.

2002-07-01

The proceedings contain the 29 papers presented at the conference plus the opening address from the chair of the Health and Safety Commission. The papers in the first session were concerned with policy, strategy and leadership and included a perspective from the offshore industry advisory committee, details of a health planning tool for occupational health assurance and lessons from occupational health management in the offshore sector. The two sessions on the second day dealt with occupational health in the offshore design process and case studies involving physical, chemical and biological agents. Topics included the need to consider occupational health when designing offshore installations, the development of a human factors engineering strategy in petrochemical engineering projects, measuring occupational exposure to hazardous chemicals, implementation of the noise at work regulations, hand arm vibration syndrome and issues with potable water maintenance. The two sessions on the third day were concerned with human factors and psychological health, and well-being and fitness for duty. Topics covered included circadian adaption to shift change in offshore shift workers, managing stress in the offshore environment, the role of employee assistance programmes in organisational stress management, health care and first aid (the revised ACOP), well-being at work, the medical and physical fitness of offshore emergency response rescue team members, the impact of health surveillance and promotion of offshore accident rates, and the implication of safety and heath of the aging of the workforce ion the Norwegian offshore industry.

Offshore production flares: a PETROBRAS review

Energy Technology Data Exchange (ETDEWEB)

Pagot, Paulo R.; Burmann, Clovis P.; Araujo, Paulo Bento de; Motomura, Tsukasa [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

2008-07-01

The purpose of the present work is to briefly present the offshore flare system technological evolution and the main design criteria for flare and its supporting structure. In order to perform the aimed task, this work was divided into two parts: the first part presents the technological evolution of the offshore production flares and the second one discusses the flare system designing criteria. The evolution of the technology associated to the offshore production flares is organized by the authors just dividing the history in four chronological phases. Each phase is defined by the predominant use of the, by the time, most up-to-date technological alternative and it will be described with the help of sketches, drawings, photographs, data and information about the platforms where such technologies were applied. The second part of the present work discusses the dimensional criteria, interesting aspects and flaws of the offshore flare systems in two different fields, which are: definition of the flare system capacity; and flow and thermal design of the flare system. (author)

Offshoring Process

DEFF Research Database (Denmark)

Slepniov, Dmitrij; Sørensen, Brian Vejrum; Katayama, Hiroshi

2011-01-01

The purpose of this chapter is to contribute to the knowledge on how production offshoring and international operations management vary across cultural contexts. The chapter attempts to shed light on how companies approach the process of offshoring in different cultural contexts. In order...... of globalisation. Yet there are clear differences in how offshoring is conducted in Denmark and Japan. The main differences are outlined in a framework and explained employing cultural variables. The findings lead to a number of propositions suggesting that the process of offshoring is not simply a uniform...... technical-rational calculation of the most efficient organisation of activities across national borders, but it is rather specific to the parent companies’ national contexts....

The Reconfiguration of Service Production Systems in Response to Offshoring

DEFF Research Database (Denmark)

Brandl, Kristin; Mol, Michael J.; Petersen, Bent

2017-01-01

Purpose: A service production system has a structure composed of task execution, agents performing tasks and a resulting service output. The purpose of this paper is to understand how such a service production system changes as a consequence of offshoring.Design/methodology/approach: Drawing...... of a service production system in response to change ignited by offshoring. The authors find recurring effects between structures that enable and constrain agents and agents who shape the structure of the production system. Research limitations/implications: The paper offers a novel contribution to the service...... operations management literature by applying practice theory. Moreover, the authors propose a detailed, activity-driven view of service production systems and service offshoring. The authors contribute to practice theory by extending its domain to operations management.Practical implications...

The influence of plate thickness on the welding residual stresses from submerged arc welding in offshore steel structures

DEFF Research Database (Denmark)

Andreassen, Michael Joachim; Yu, Zhenzhen; Liu, Stephen

2017-01-01

Welding-induced residual tensile stresses and distortion have become a major concern in relation to the structural integrity of welded structures within the offshore wind industry. The stresses have a negative impact on the integrity of the welded joint, as they promote distortion, reduce fatigue...... leading to a better understanding of the distribution and development of the welding residual stresses. This can later be used to optimize the fatigue design, providing a more efficient and improved design. In this context, the current research is expected to benefit the offshore industry by leading...... to an improved design, which consequently may be included in future norms and standards. Submerged Arc Welding (SAW) was used to make a fully penetrated butt weld in 10 mm and 40 mm thick steel plates with the same welding parameters as used in the production procedures. The base material is thermomechanical hot...

Review of technology for Arctic offshore oil and gas recovery

Energy Technology Data Exchange (ETDEWEB)

Sackinger, W. M.

1980-08-01

The technical background briefing report is the first step in the preparation of a plan for engineering research oriented toward Arctic offshore oil and gas recovery. A five-year leasing schedule for the ice-prone waters of the Arctic offshore is presented, which also shows the projected dates of the lease sale for each area. The estimated peak production rates for these areas are given. There is considerable uncertainty for all these production estimates, since no exploratory drilling has yet taken place. A flow chart is presented which relates the special Arctic factors, such as ice and permafrost, to the normal petroleum production sequence. Some highlights from the chart and from the technical review are: (1) in many Arctic offshore locations the movement of sea ice causes major lateral forces on offshore structures, which are much greater than wave forces; (2) spray ice buildup on structures, ships and aircraft will be considerable, and must be prevented or accommodated with special designs; (3) the time available for summer exploratory drilling, and for deployment of permanent production structures, is limited by the return of the pack ice. This time may be extended by ice-breaking vessels in some cases; (4) during production, icebreaking workboats will service the offshore platforms in most areas throughout the year; (5) transportation of petroleum by icebreaking tankers from offshore tanker loading points is a highly probable situation, except in the Alaskan Beaufort; and (6) Arctic pipelines must contend with permafrost, making instrumentation necessary to detect subtle changes of the pipe before rupture occurs.

Large deformation of uniaxially loaded slender microbeams on the basis of modified couple stress theory: Analytical solution and Galerkin-based method

Science.gov (United States)

Kiani, Keivan

2017-09-01

Large deformation regime of micro-scale slender beam-like structures subjected to axially pointed loads is of high interest to nanotechnologists and applied mechanics community. Herein, size-dependent nonlinear governing equations are derived by employing modified couple stress theory. Under various boundary conditions, analytical relations between axially applied loads and deformations are presented. Additionally, a novel Galerkin-based assumed mode method (AMM) is established to solve the highly nonlinear equations. In some particular cases, the predicted results by the analytical approach are also checked with those of AMM and a reasonably good agreement is reported. Subsequently, the key role of the material length scale on the load-deformation of microbeams is discussed and the deficiencies of the classical elasticity theory in predicting such a crucial mechanical behavior are explained in some detail. The influences of slenderness ratio and thickness of the microbeam on the obtained results are also examined. The present work could be considered as a pivotal step in better realizing the postbuckling behavior of nano-/micro- electro-mechanical systems consist of microbeams.

Load Identification of Offshore Platform for Fatigue Life Estimation

DEFF Research Database (Denmark)

Perisic, Nevena; Kirkegaard, Poul Henning; Tygesen, Ulf T.

2014-01-01

of the structure and the discrete Kalman filter which recursively estimates unknown states of the system in real time. As a test-case, the algorithm is designed to estimate the equivalent total loading forces of the structure. The loads are estimated from noised displacement measurements of a single location...... on the topside of the offshore structure. The method is validated using simulated data for two wave loading cases: regular and irregular wave loadings.......The lifetime of an offshore platform is typically governed by accumulated fatigue damage. Thus, the load time history is an essential parameter for prediction of the lifetime of the structure and its components. Consequently, monitoring of structural loads is of special importance in relation to re...

Gaining Flexibility and Innovation through Offshore Outsourcing

Directory of Open Access Journals (Sweden)

Michela Pellicelli

2018-05-01

Full Text Available Recently, offshore outsourcing has become extremely important for companies that compete worldwide. In many industries, only companies that manage to be competitive globally can aspire to attain sustainable competitive advantages. Therefore, offshore outsourcing has become essential for many companies and recently has become more and more a vital part of the long-term strategies of the leading firms. The rapidly shifting conditions in the marketplace is forcing management to constantly review and defend its core competencies. Management is now confronted with a higher level of complexity and disruptions brought about in particular by the new waves of globalization and the irresistible march of technological changes. For these reasons, offshore outsourcing is transforming the functions of the traditional firms into a network of competencies. The tendency to offshore most of the productive and economic activities and processes can lead companies to transform themselves into virtual organizations, where all the functions could be outsourced through the formation of flexible networks and agile organizational structures.

Offshore Investment Funds

Directory of Open Access Journals (Sweden)

Shang-Jin Wei

1999-12-01

Full Text Available Offshore investment funds are alleged to have engaged in trading behavior that is different from their onshore counterparts because they may be subject to less supervision and regulation. In particular, they may trade more intensely. They could also pursue more aggressively certain trading strategies such as positive feedback trading or herding that could contribute to a greater volatility in the market. Using a unique data set, this chapter compares the trading behavior in the Korean stock market between offshore investment funds with their onshore counterparts registered in the US and UK. There are a number of interesting findings. First, there is indeed evidence suggesting that the offshore funds trade more intensely than their onshore counterparts. Second, however, there is no evidence that the offshore funds engage in positive feedback trading. In contrast, there is strong evidence that the funds from the U.S. and U.K. do. Third, while offshore funds do herd, they do so far less than onshore funds in the U.S. or UK. Fourth, offshore funds hold less glamour stocks (e.g. stocks with high P/E in their portfolio than funds in the U.S. or U.K. do. Moreover, flight to glamour stocks during the in-crisis period is less evident in the case of offshore funds. In sum, offshore funds are no especially worrisome monsters.

Modeling and Simulation of Offshore Wind Power Platform for 5 MW Baseline NREL Turbine

Science.gov (United States)

Roni Sahroni, Taufik

2015-01-01

This paper presents the modeling and simulation of offshore wind power platform for oil and gas companies. Wind energy has become the fastest growing renewable energy in the world and major gains in terms of energy generation are achievable when turbines are moved offshore. The objective of this project is to propose new design of an offshore wind power platform. Offshore wind turbine (OWT) is composed of three main structures comprising the rotor/blades, the tower nacelle, and the supporting structure. The modeling analysis was focused on the nacelle and supporting structure. The completed final design was analyzed using finite element modeling tool ANSYS to obtain the structure's response towards loading conditions and to ensure it complies with guidelines laid out by classification authority Det Norske Veritas. As a result, a new model of the offshore wind power platform for 5 MW Baseline NREL turbine was proposed. PMID:26550605

Reliability Analysis of Tubular Joints in Offshore Structures

DEFF Research Database (Denmark)

Thoft-Christensen, Palle; Sørensen, John Dalsgaard

1987-01-01

Reliability analysis of single tubular joints and offshore platforms with tubular joints is" presented. The failure modes considered are yielding, punching, buckling and fatigue failure. Element reliability as well as systems reliability approaches are used and illustrated by several examples....... Finally, optimal design of tubular.joints with reliability constraints is discussed and illustrated by an example....

How Offshoring Elicits Reconfiguration of the Service Production System

DEFF Research Database (Denmark)

Brandl, Kristin; Mol, Michael J.; Petersen, Bent

Service production systems can be seen as a structure consisting of task execution, resources executing tasks and the service output received by the client. Offshoring acts as an exogenous shock to such a service production system. Drawing on practice theory and applying a multiple case methodology...... of the impact of offshoring and to practice theory....

Validated Loads Prediction Models for Offshore Wind Turbines for Enhanced Component Reliability

DEFF Research Database (Denmark)

Koukoura, Christina

To improve the reliability of offshore wind turbines, accurate prediction of their response is required. Therefore, validation of models with site measurements is imperative. In the present thesis a 3.6MW pitch regulated-variable speed offshore wind turbine on a monopole foundation is built...... are used for the modification of the sub-structure/foundation design for possible material savings. First, the background of offshore wind engineering, including wind-wave conditions, support structure, blade loading and wind turbine dynamics are presented. Second, a detailed description of the site...

Risk assessment by integrating interpretive structural modeling and Bayesian network, case of offshore pipeline project

International Nuclear Information System (INIS)

Wu, Wei-Shing; Yang, Chen-Feng; Chang, Jung-Chuan; Château, Pierre-Alexandre; Chang, Yang-Chi

2015-01-01

The sound development of marine resource usage relies on a strong maritime engineering industry. The perilous marine environment poses the highest risk to all maritime work. It is therefore imperative to reduce the risk associated with maritime work by using some analytical methods other than engineering techniques. This study addresses this issue by using an integrated interpretive structure modeling (ISM) and Bayesian network (BN) approach in a risk assessment context. Mitigating or managing maritime risk relies primarily on domain expert experience and knowledge. ISM can be used to incorporate expert knowledge in a systematic manner and helps to impose order and direction on complex relationships that exist among system elements. Working with experts, this research used ISM to clearly specify an engineering risk factor relationship represented by a cause–effect diagram, which forms the structure of the BN. The expert subjective judgments were further transformed into a prior and conditional probability set to be embedded in the BN. We used the BN to evaluate the risks of two offshore pipeline projects in Taiwan. The results indicated that the BN can provide explicit risk information to support better project management. - Highlights: • We adopt an integrated method for risk assessment of offshore pipeline projects. • We conduct semi-structural interview with the experts for risk factor identification. • Interpretive structural modeling helps to form the digraph of Bayesian network (BN) • We perform the risk analysis with the experts by building a BN. • Risk evaluations of two case studies using the BN show effectiveness of the methods

Natural frequency and vibration analysis of jacket type foundation for offshore wind power

Science.gov (United States)

Hung, Y.-C.; Chang, Y.-Y.; Chen, S.-Y.

2017-12-01

There are various types of foundation structure for offshore wind power, engineers may assess the condition of ocean at wind farm, and arrange the transportation, installation of each structure members, furthermore, considering the ability of manufacture steel structure as well, then make an optimum design. To design jacket offshore structure, unlike onshore cases, offshore structure also need to estimate the wave excitation effect. The aim of this paper is to study the difference of natural frequency between different kinds of structural stiffness and discuss the effect of different setting of boundary condition during analysis, besides, compare this value with the natural frequency of sea wave, in order to avoid the resonance effect. In this paper, the finite element analysis software ABAQUS is used to model and analyze the natural vibration behavior of the jacket structure.

Generalized Stability Analysis of Capillary Flow in Slender V-Grooves

Science.gov (United States)

White, Nicholas; Troian, Sandra

2017-11-01

Spontaneous capillary flow, an especially rapid process in slender open microchannels resembling V-grooves, is of significant importance to many applications requiring passive robust flow control. Many types of biomedical devices for point-of-care use in developing countries are being designed around this principle. Important fundamental work by Romero and Yost (1996) and Weislogel (1996) elucidated the behavior of Newtonian films in slender V-grooves driven to flow by the streamwise change in capillary pressure due to the change in radius of curvature of the circular arc describing the interface of wetting or non-wetting fluids. Self-similar solutions describing Washburn type dynamics were found but other solutions are possible. Here we extend the Romero and Yost model to include a variety of inlet and outlet boundary conditions and examine the transient growth and generalized stability of perturbations to steady state and self-similar flows. Although most cases examined for wetting fluids exhibit robust stability against small perturbations, some exceptions reveal unstable flow. In total, these results support decades of experimental work which has found this method of flow control to be especially reliable, robust and self-healing. The authors gratefully acknowledge financial support from the 2016 NASA/Jet Propulsion Laboratory President's and Director's Fund as well as a 2017 NASA Space Technology Research Fellowship.

Whether and What to Offshore?

DEFF Research Database (Denmark)

Jensen, Peter Ørberg; Pedersen, Torben

In this article, we explore the idea that offshoring of services and technical work should be regarded as a dynamic process that evolves over time. Firms gradually move from offshoring of simple, standardized activities towards offshoring of advanced activities when they accumulate experience...... with offshoring, and this type of offshoring comes with an entirely different set of characteristics compared to traditional, cost-seeking offshoring. Based on a unique survey among the total population of firms in the eastern region of Denmark, we analyze some of the dynamics of this process through a model...... that incorporates two different aspects of the process of offshoring. First, we approach the question of whether to offshore and establish a baseline that investigates the determinants of firms’ participation—or lack thereof—in offshoring. Secondly, we approach the question of what to offshore and the subsequent...

Industrial opportunities - offshore

International Nuclear Information System (INIS)

Gerrits, D.J.

1998-01-01

Industrial opportunities available in the Canadian offshore petroleum industry are discussed. Oil has been produced offshore from Nova Scotia since 1992, and offshore from Newfoundland since 1997. Special needs that must be addressed in offshore operations in eastern Canada such as the cold North Atlantic environment, isolation, logistics, safety, and quality assurance, are examined. The most obvious opportunities lie with the designing, building and installing the facilities needed to extract oil and gas from beneath the sea floor and transport it to market. However, there are also opportunities in designing and fabricating clothing, customized food containers and other equipment for offshore needs. Short term opportunities also exist in the decommissioning of depleted production fields and their facilities. One of the greatest obstacles facing new entrants into the offshore oil and gas industry is the lack of a track record. To meet this challenge, the ability to seek out partners to pursue local and international opportunities through joint ventures, strategic alliances and technology sharing partnering arrangements is of great importance. It may be the difference between success and failure. 6 figs

From Offshoring to Backshoring

DEFF Research Database (Denmark)

Slepniov, Dmitrij; Madsen, Erik Skov

2015-01-01

The purpose of this paper is to examine the evolution of offshoring over time. The paper employs qualitative methodology and on the basis of two case studies of Danish companies, it develops a framework conceptualizing the stages of offshoring and highlights the factors driving the transition...... between these stages. The framework challenges the linear nature of offshoring and proposes the existence of ‘the pendulum effect’. The pendulum effect suggests that the modes of offshoring (i.e. captive and non-captive) and geographies of offshoring (i.e. home and abroad) are not static; rather...

Too much or too little of R&D offshoring : The impact of captive offshoring and contract offshoring on innovation performance

NARCIS (Netherlands)

Steinberg, Philip; Procher, Vivien D.; Urbig, Diemo

2017-01-01

Innovating firms may acquire foreign knowledge and improve their innovation performance by offshoring their R&D activities to their own foreign affiliates (captive offshoring) as well as by contracting out their R&D to external foreign parties (contract offshoring). This study examines the impact of

Review of technology for Arctic offshore oil and gas recovery. Appendices

Energy Technology Data Exchange (ETDEWEB)

Sackinger, W. M.

1980-06-06

This volume contains appendices of the following: US Geological Survey Arctic operating orders, 1979; Det Noske Vertas', rules for the design, construction and inspection of offshore technology, 1977; Alaska Oil and Gas Association, industry research projects, March 1980; Arctic Petroleum Operator's Association, industry research projects, January 1980; selected additional Arctic offshore bibliography on sea ice, icebreakers, Arctic seafloor conditions, ice-structures, frost heave and structure icing.

Safety in offshore engineering an academic course covering safety in offshore wind

NARCIS (Netherlands)

Cerda Salzmann, D.J.

2011-01-01

Offshore projects are known for their challenging conditions, generally leading to high risks. Therefore no offshore project can go without a continuous and extensive assessment on safety issues. The Delft University of Technology is currently developing a course "Safety in Offshore Engineering"

What can wave energy learn from offshore oil and gas?

Science.gov (United States)

Jefferys, E R

2012-01-28

This title may appear rather presumptuous in the light of the progress made by the leading wave energy devices. However, there may still be some useful lessons to be learnt from current 'offshore' practice, and there are certainly some awful warnings from the past. Wave energy devices and the marine structures used in oil and gas exploration as well as production share a common environment and both are subject to wave, wind and current loads, which may be evaluated with well-validated, albeit imperfect, tools. Both types of structure can be designed, analysed and fabricated using similar tools and technologies. They fulfil very different missions and are subject to different economic and performance requirements; hence 'offshore' design tools must be used appropriately in wave energy project and system design, and 'offshore' cost data should be adapted for 'wave' applications. This article reviews the similarities and differences between the fields and highlights the differing economic environments; offshore structures are typically a small to moderate component of field development cost, while wave power devices will dominate overall system cost. The typical 'offshore' design process is summarized and issues such as reliability-based design and design of not normally manned structures are addressed. Lessons learned from poor design in the past are discussed to highlight areas where care is needed, and wave energy-specific design areas are reviewed. Opportunities for innovation and optimization in wave energy project and device design are discussed; wave energy projects must ultimately compete on a level playing field with other routes to low CO₂ energy and/or energy efficiency. This article is a personal viewpoint and not an expression of a ConocoPhillips position.

Offshore in depth

Energy Technology Data Exchange (ETDEWEB)

Ebdon, J F

1968-08-01

The world-wide scope of offshore areas is discussed. Offshore areas of the U.S. and the world are where one of the ''hottest'' hydrocarbon booms--drilling, production, and pipelining--are in action today. Most of the current activity in offshore exploration and drilling is crude oil directed. However, big non-associated natural gas finds have been made. Additionally, for every barrel of crude oil produced, either or both associated natural gas and dissolved natural gas are produced in some varying ratio as casinghead gas. Thus, with worldwide production of some 2.5-million bbl of crude oil per day from offshore areas of Free-World countries, there are vast volumes of casinghead natural gas produced, over and above that produced from non-associated natural gas wells to the seaward of land masses. If offshore gas of any classification is produced in commercial volumes close to onshore population centers, then the possibility of marketing is fairly good. If remote from population centers, it is usually flared or shut-in. The development of gas liquefaction and cryogenic tankers has started, but international ocean traffic in LNG is still in its infancy. Current offshore gas pipelines are described.

On the structure, interaction, and breakdown characteristics of slender wing vortices at subsonic, transonic, and supersonic speeds

Science.gov (United States)

Erickson, Gary E.; Schreiner, John A.; Rogers, Lawrence W.

1989-01-01

Slender wing vortex flows at subsonic, transonic, and supersonic speeds were investigated in a 6 x 6 ft wind tunnel. Test data obtained include off-body and surface flow visualizations, wing upper surface static pressure distributions, and six-component forces and moments. The results reveal the transition from the low-speed classical vortex regime to the transonic regime, beginning at a freestream Mach number of 0.60, where vortices coexist with shock waves. It is shown that the onset of core breakdown and the progression of core breakdown with the angle of attack were sensitive to the Mach number, and that the shock effects at transonic speeds were reduced by the interaction of the wing and the lead-edge extension (LEX) vortices. The vortex strengths and direct interaction of the wing and LEX cores (cores wrapping around each other) were found to diminish at transonic and supersonic speeds.

Simplified Technique for Predicting Offshore Pipeline Expansion

Science.gov (United States)

Seo, J. H.; Kim, D. K.; Choi, H. S.; Yu, S. Y.; Park, K. S.

2018-06-01

In this study, we propose a method for estimating the amount of expansion that occurs in subsea pipelines, which could be applied in the design of robust structures that transport oil and gas from offshore wells. We begin with a literature review and general discussion of existing estimation methods and terminologies with respect to subsea pipelines. Due to the effects of high pressure and high temperature, the production of fluid from offshore wells is typically caused by physical deformation of subsea structures, e.g., expansion and contraction during the transportation process. In severe cases, vertical and lateral buckling occurs, which causes a significant negative impact on structural safety, and which is related to on-bottom stability, free-span, structural collapse, and many other factors. In addition, these factors may affect the production rate with respect to flow assurance, wax, and hydration, to name a few. In this study, we developed a simple and efficient method for generating a reliable pipe expansion design in the early stage, which can lead to savings in both cost and computation time. As such, in this paper, we propose an applicable diagram, which we call the standard dimensionless ratio (SDR) versus virtual anchor length (L A ) diagram, that utilizes an efficient procedure for estimating subsea pipeline expansion based on applied reliable scenarios. With this user guideline, offshore pipeline structural designers can reliably determine the amount of subsea pipeline expansion and the obtained results will also be useful for the installation, design, and maintenance of the subsea pipeline.

Modeling and Simulation of Offshore Wind Power Platform for 5 MW Baseline NREL Turbine

Directory of Open Access Journals (Sweden)

Taufik Roni Sahroni

2015-01-01

Full Text Available This paper presents the modeling and simulation of offshore wind power platform for oil and gas companies. Wind energy has become the fastest growing renewable energy in the world and major gains in terms of energy generation are achievable when turbines are moved offshore. The objective of this project is to propose new design of an offshore wind power platform. Offshore wind turbine (OWT is composed of three main structures comprising the rotor/blades, the tower nacelle, and the supporting structure. The modeling analysis was focused on the nacelle and supporting structure. The completed final design was analyzed using finite element modeling tool ANSYS to obtain the structure’s response towards loading conditions and to ensure it complies with guidelines laid out by classification authority Det Norske Veritas. As a result, a new model of the offshore wind power platform for 5 MW Baseline NREL turbine was proposed.

The Offshore New European Wind Atlas

Science.gov (United States)

Karagali, I.; Hahmann, A. N.; Badger, M.; Hasager, C.; Mann, J.

2017-12-01

The New European Wind Atlas (NEWA) is a joint effort of research agencies from eight European countries, co-funded under the ERANET Plus Program. The project is structured around two areas of work: development of dynamical downscaling methodologies and measurement campaigns to validate these methodologies, leading to the creation and publication of a European wind atlas in electronic form. This atlas will contain an offshore component extending 100 km from the European coasts. To achieve this, mesoscale models along with various observational datasets are utilised. Scanning lidars located at the coastline were used to compare the coastal wind gradient reproduced by the meso-scale model. Currently, an experimental campaign is occurring in the Baltic Sea, with a lidar located in a commercial ship sailing from Germany to Lithuania, thus covering the entire span of the south Baltic basin. In addition, satellite wind retrievals from scatterometers and Synthetic Aperture Radar (SAR) instruments were used to generate mean wind field maps and validate offshore modelled wind fields and identify the optimal model set-up parameters.The aim of this study is to compare the initial outputs from the offshore wind atlas produced by the Weather & Research Forecasting (WRF) model, still in pre-operational phase, and the METOP-A/B Advanced Scatterometer (ASCAT) wind fields, reprocessed to stress equivalent winds at 10m. Different experiments were set-up to evaluate the model sensitivity for the various domains covered by the NEWA offshore atlas. ASCAT winds were utilised to assess the performance of the WRF offshore atlases. In addition, ASCAT winds were used to create an offshore atlas covering the years 2007 to 2016, capturing the signature of various spatial wind features, such as channelling and lee effects from complex coastal topographical elements.

Economic optimization of offshore wind farms

International Nuclear Information System (INIS)

Pauling, T.

1996-09-01

The study on the title subject continues the development of a cost model for offshore wind farms started at the Institute for Wind Energy (IW) in 1995, and applies it on different kinds of cost analyses. The model will be considered within the European research project 'Structural and Economic Optimization of Bottom-Mounted Offshore Wind Energy Converters' (Opti-OWECS, JOR3-CT95-0087) co-ordinated by the IW, where also the cost analyses and optimization will be extended. The conclusions of the investigations have already been presented at the European Union Wind Energy Conference '96 at Goeteborg, Sweden. In Chapter 1, a short overview of former offshore studies and projects is given, especially those dealing with cost analysis. Typical cost breakdowns of offshore and onshore wind farms are compared. Chapter 2 contains a brief description of the cost model in its present state. The recent improvements and extensions are documented in Chapter 3, and a validation by means of a recalculation of two former offshore studies is carried out in Chapter 4. In Chapter 5, four different offshore sites are compared with respect to the same farm size and an optimized farm design: Jade in the German part of the North Sea near Wilhelmshafen; Swansea Bay in the Bristol Channel at the British Atlantic Coast; Rostock at the German Baltic Coast, and IJmuiden in the Dutch part of the North Sea. In Chapter 6, a sensitivity study is carried out for a variety of site, design and economical parameters. The results of this project are summarized in Chapter 7, and an outlook is given in Chapter 8. The appendix contains among others a description of the SCOptiM2 code, where the model is implemented, as well as data obtained from the parameter studies and design optimizations. 30 figs., 8 tabs., 6 appendices, 40 refs

Travelling-wave similarity solutions for a steadily translating slender dry patch in a thin fluid film

KAUST Repository

Yatim, Y. M.; Duffy, B. R.; Wilson, S. K.

2013-01-01

A novel family of three-dimensional travelling-wave similarity solutions describing a steadily translating slender dry patch in an infinitely wide thin fluid film on an inclined planar substrate when surface-tension effects are negligible

Governance of Arctic Offshore Oil and Gas

DEFF Research Database (Denmark)

Bringing together leading experts from various disciplines, this book offers a comprehensive study of the governance of offshore oil and gas activities in the circumpolar Arctic. As a consequence of energy globalisation, and of a sharp increase in world energy demand, the Arctic Ocean is also now...... being targeted for its offshore oil and gas resources, at the same time as an increasing demand for democratic legitimisation and recognition of the rights of indigenous peoples is emerging in the civil spheres of society. The volume analyses how, in the daunting context of climate change......, the interactions between the various levels of governance structure the policy process and impact on the efficiency of environmental management and the effectiveness of public participation, including the participation of indigenous peoples. Any governance system for Arctic offshore oil and gas activities...

Slender body treatment of some specialized problems associated with elliptic-cross-section missile configurations

Science.gov (United States)

Barger, R. L.

1977-01-01

Slender body methods were applied to some specialized problems associated with missile configurations with elliptic cross sections. Expressions are derived for computing the velocity distribution on the nose section when the ellipse eccentricity is varying longitudinally on the missile. The cross flow velocity on a triform fin section is also studied.

Slender body theory programmed for bodies with arbitrary cross section. [including fuselages

Science.gov (United States)

Werner, J.; Krenkel, A. R.

1978-01-01

A computer program developed for determining the subsonic pressure, force, and moment coefficients for a fuselage-type body using slender body theory is described. The program is suitable for determining the angle of attack and sideslipping characteristics of such bodies in the linear range where viscous effects are not predominant. Procedures developed which are capable of treating cross sections with corners or regions of large curvature are outlined.

Review of control algorithms for offshore wind turbines

Energy Technology Data Exchange (ETDEWEB)

Spruce, C J; Markou, H; Leithead, W E; Dominguez Ruiz, S

2005-07-01

Innovative turbine control strategies could allow the improvements to cost and performance considered essential to reduce the cost of energy from offshore wind farms around the UK. This project reviewed and investigated the possibility for further development of a power control algorithm originally developed by NEG Micon Rotors Ltd for use with offshore wind turbines in the hope that more advanced algorithms would reduce the loads on, and hence the costs of, components such as the foundation/support structure, tower, blades and bedplate. Three models (simulation model, linearisation of the simulation model and control model) were produced in order to conduct the review. Application of these models produced the conclusion that the size of the latest generation of offshore wind turbines has now reached a level where performance is starting to be constrained by fundamental factors in the dynamics caused by the machine's physical size. It was also concluded that an ideal control strategy could achieve potential cost savings for the tower and support structure of 5-10% of the total cost of the turbine plus support structure. Further work to develop controllers to reduce loads in the tower and support structure is urged. The report considers non-linear simulation, the linear model, the control model, general operation of the controller, the drive train damping filter, torque control, pitch control and advanced algorithms, and makes detailed recommendations for future work.

The Effects of Anthropogenic Structures on Habitat Connectivity and the Potential Spread of Non-Native Invertebrate Species in the Offshore Environment.

Science.gov (United States)

Simons, Rachel D; Page, Henry M; Zaleski, Susan; Miller, Robert; Dugan, Jenifer E; Schroeder, Donna M; Doheny, Brandon

2016-01-01

Offshore structures provide habitat that could facilitate species range expansions and the introduction of non-native species into new geographic areas. Surveys of assemblages of seven offshore oil and gas platforms in the Santa Barbara Channel revealed a change in distribution of the non-native sessile invertebrate Watersipora subtorquata, a bryozoan with a planktonic larval duration (PLD) of 24 hours or less, from one platform in 2001 to four platforms in 2013. We use a three-dimensional biophysical model to assess whether larval dispersal via currents from harbors to platforms and among platforms is a plausible mechanism to explain the change in distribution of Watersipora and to predict potential spread to other platforms in the future. Hull fouling is another possible mechanism to explain the change in distribution of Watersipora. We find that larval dispersal via currents could account for the increase in distribution of Watersipora from one to four platforms and that Watersipora is unlikely to spread from these four platforms to additional platforms through larval dispersal. Our results also suggest that larvae with PLDs of 24 hours or less released from offshore platforms can attain much greater dispersal distances than larvae with PLDs of 24 hours or less released from nearshore habitat. We hypothesize that the enhanced dispersal distance of larvae released from offshore platforms is driven by a combination of the offshore hydrodynamic environment, larval behavior, and larval release above the seafloor.

Nonconsensual clinical trials: a foreseeable risk of offshoring under global corporatism.

Science.gov (United States)

Spielman, Bethany

2015-03-01

This paper explores the connection of offshoring and outsourcing to nonconsensual global pharmaceutical trials in low-income countries. After discussing reasons why the topic of nonconsensual offshored clinical trials may be overlooked in bioethics literature, I suggest that when pharmaceutical corporations offshore clinical trials today, nonconsensual experiments are often foreseeable and not simply the result of aberrant ethical conduct by a few individuals. Offshoring of clinical trials is structured so that experiments can be presented as health care in a unique form of outsourcing from the host country to pharmaceutical corporations. Bioethicists' assessments of the risks and potential benefits of offshore corporate pharmaceutical trials should therefore systematically include not only the hoped for benefits and the risks of the experimental drug but also the risk that subjects will not have consented, as well as the broader international consequences of nonconsensual experimentation.

Internationalization in the offshore sector and the use of strategic alliances. Kongsberg Offshore AS - A case study; Internasjonalisering i offshorebransjen og bruk av strategiske allianser. Kongsberg Offshore AS - et casestudium

Energy Technology Data Exchange (ETDEWEB)

Enger, Ole Peder; Andreassen, Yngve

2000-06-01

The structure of the Norwegian offshore sector is characterized by many small technology companies and only a few big ones. At the same time, operators prefer to deal with as few contractors as possible. Thus, the small technology companies must operate as subcontractors or cooperate as joint venture companies in order to win supply contracts. This report studies Kongsberg Offshore AS, or KOS, which is a daughter company of Food Machinery Corporation (FMC). KOS is a leading supplier of ''turnkey'' systems for sub see production and measuring systems and has had great success in its internationalization.

A quick seismic assessment method for jacket type offshore structures by combining push-over and nonlinear time history analyses

Energy Technology Data Exchange (ETDEWEB)

Karimiyan, S.; Hosseini, M. [International Inst. of Earthquake Engineering and Seismology, Tehran (Iran, Islamic Republic of); Karimiyan, M. [Islamic Azad Univ., Tehran (Iran, Islamic Republic of). Earthquake Eng. Dept., School of Engineering

2010-07-01

Several offshore structures are located in seismic regions. In order to upgrade their seismic behaviour, their seismic vulnerability must be evaluated. It is thought that the most reliable type of analysis for seismic evaluation is nonlinear time history analysis (NLTHA), however, it is known to be a very time consuming method. This paper presented a quick procedure by combining the push over analysis (POA) and the NLTHA. The paper discussed both methods in detail. In order to identify the more critical members of the structure, based on the range of their plastic deformations, some POA were first performed. The NLTHA was then performed, focusing on the critical members, to obtain their vulnerability with higher reliability. An offshore structure of jacket type, installed in the Lavan oil field in the Persian Gulf in 1970, was also considered in order to demonstrate the efficiency of the proposed method. It was concluded from the numerical results that combining POA and NLTHA was a quick and reliable seismic evaluation method. The results demonstrated that although the vulnerability of the jacket structure was not very high, the level of damage was not the same for different members, and was dependent on their location in the structure and also its geometric orientation and load bearing situation. 6 refs., 1 tab., 8 figs.

Domestic R&D and Offshoring

DEFF Research Database (Denmark)

Junge, Martin; Sørensen, Anders

2017-01-01

survey and register data. No evidence is found for a lower probability of own R&D after offshoring takes place compared to before. Moreover, offshoring does not lead to lower R&D intensity in general. However, firms that offshore R&D activity have larger R&D intensity after offshoring has taken place...

Wave Simulation in Truncated Domains for Offshore Applications

NARCIS (Netherlands)

Wellens, P.R.

2012-01-01

There is a desire to assess extreme wave loads on offshore structures like Floating Production, Storage and Offloading (FPSO) vessels, either for design, or for evaluation when circumstances near the structure change. Design formulae for extreme wave loads are scarce and

Current trends in offshore technology

International Nuclear Information System (INIS)

Korsgaard, J.

1994-01-01

Although this is a technical symposium concerning advances in the technology of producing oil and gas offshore, a keynote address would not be complete without mentioning non-technical factors which are extremely important for the business of producing oil and gas offshore. These are political factors and economic factors. Offshore operations are an easy target for political forces that are opposed to marine operations involving the production and transfer of hydrocarbons. For example, the oil pollution act of 1990 was a reaction to the Exxon Valdez grounding in Alaska and this act has added significantly to the risk and cost of operating offshore. Another example of this is that it is becoming more and more difficult to dispose of produced water offshore. Producing oil and gas offshore is a business that competes with other energy sources such as coal and oil and gas from wells on land. The offshore oil can only compete with these other resources by providing the same product at a competitive price. Since offshore operations are inherently more costly than land operations, the offshore oil field or gas field must be significantly larger than a land field in order to be produced. Also the offshore oil field or gas field is more susceptible to environmental risks from weather. On a more positive note, there are technical developments which are taking place and have continuously taken place to make offshore oil and gas both more economic and safer to produce. These developments are briefly discussed

Review of potential impacts to sea turtles from underwater explosive removal of offshore structures

International Nuclear Information System (INIS)

Viada, Stephen T.; Hammer, Richard M.; Racca, Roberto; Hannay, David; Thompson, M. John; Balcom, Brian J.; Phillips, Neal W.

2008-01-01

The purpose of this study was to collect and synthesize existing information relevant to the explosive removal of offshore structures (EROS) in aquatic environments. Data sources were organized and summarized by topic - explosive removal methods, physics of underwater explosions, sea turtle resources, documented impacts to sea turtles, and mitigation of effects. Information was gathered via electronic database searches and literature source review. Bulk explosive charges are the most commonly used technique in EROS. While the physical principles of underwater detonations and the propagation of pressure and acoustic waves are well understood, there are significant gaps in the application of this knowledge. Impacts to sea turtles from explosive removal operations may range from non-injurious effects (e.g. acoustic annoyance; mild tactile detection or physical discomfort) to varying levels of injury (i.e. non-lethal and lethal injuries). Very little information exists regarding the impacts of underwater explosions on sea turtles. Effects of explosions on turtles often must be inferred from documented effects to other vertebrates with lungs or other gas-containing organs, such as mammals and most fishes. However, a cautious approach should be used when determining impacts to sea turtles based on extrapolations from other vertebrates. The discovery of beached sea turtles and bottlenose dolphins following an explosive platform removal event in 1986 prompted the initiation of formal consultation between the U.S. Department of the Interior, Minerals Management Service (MMS) and the National Marine Fisheries Service (NMFS), authorized through the Endangered Species Act Section 7, to determine a mechanism to minimize potential impacts to listed species. The initial consultation resulted in a requirement for oil and gas companies to obtain a permit (through separate consultations on a case-by-case basis) prior to using explosives in Federal waters. Because many offshore

Offshoring and International Competitiveness

DEFF Research Database (Denmark)

Ørberg Jensen, Peter D.; Pedersen, Torben

2012-01-01

During the past decade, offshoring has become an established business practice. Yet it is still more common to offshore less advanced tasks compared with offshoring more advanced tasks, i.e., tasks closer to the core activities of the firm. The latter is a new phenomenon which raises many new iss...

Virtual 5-French intra-aortic pumping using a Glidesheath Slender and 6-French intra-aortic balloon catheter

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Akihiko, E-mail: a-takahashi@wine.ocn.ne.jp; Taniguchi, Norimasa; Mizuguchi, Yukio; Yamada, Takeshi; Nakajima, Shunsuke; Hashimoto, Sho; Hata, Tetsuya

2015-07-15

Objectives: The aim of this study was to evaluate the feasibility and safety of the 6-Fr Glidesheath Slender, which has equivalent outer size to the conventional 5-Fr sheath, for use with the 6-Fr intra-aortic balloon pump (IABP) catheter. Methods: Between May 2014 and March 2015, 24 patients with acute coronary syndrome underwent percutaneous coronary intervention using a 6-Fr IABP catheter through a 6-Fr Glidesheath Slender for support. The adverse events, including access site complications, kinking of the sheath during the procedure, and any evidence of balloon pump failure, were retrospectively investigated. Results: Insertion of the IABP catheter through either the femoral or brachial artery was successful in all patients. The mean support time was 32.4 ± 22.0 h. No major hemorrhagic event or severe limb ischemia was observed. Kinking of the shaft occurred during insertion in one patient; however, the subsequent balloon pumping was well maintained and did not require exchange of the sheath or IABP catheter. No kind of IABP failure was observed. Conclusion: Although this sheath was originally designed to allow radial access, our results suggest that the use of the Glidesheath Slender is feasible for insertion of the 6-Fr IABP catheter through the brachial and femoral arteries, and may reduce vascular complications in patients who undergo percutaneous coronary intervention.

Offshore Transmission Technology

Energy Technology Data Exchange (ETDEWEB)

NONE

2012-10-15

The purpose of this document is to give an overview of offshore electricity transmission technologies. In particular this document is concerned with the use of High Voltage Direct Current (HVDC) systems and more specifically with the development of Voltage Source Converter (VSC) technology. This report outlines the current state of the main technology groups required for offshore HVDC transmission as well as giving examples of offshore projects (both current and future). Finally some indications of likely unit costs for HV assets are given.

Design and Analysis of Jacket Substructures for Offshore Wind Turbines

Directory of Open Access Journals (Sweden)

I-Wen Chen

2016-04-01

Full Text Available This study focused on investigating various existing types of offshore jacket substructures along with a proposed twisted-tripod jacket type (modified jacket (MJ-structures. The architectures of the three-leg structure, as well as the patented twisted jacket structure motivated the design of the proposed MJ-structures. The dimensions of the structures were designed iteratively using static stress analysis to ensure that all structures had a similar level of load-carrying capability. The numerical global buckling analyses were performed for all structures after the validation by the scaled-down experiments. The local buckling strength of all compressive members was analyzed using the NORSOK standard. The results showed that the proposed MJ-structures possess excellent structural behavior and few structural nodes and components competitive with the patented twisted jacket structures, while still maintaining the advantages of low material usage similar to the three-leg jacket structures. This study provides alternatives for the initial selection and design of offshore wind turbine substructures for green energy applications.

Reliability Assessment and Reliability-Based Inspection and Maintenance of Offshore Wind Turbines

DEFF Research Database (Denmark)

Ramirez, José Rangel

actions are the most relevant and effective means of control of deterioration. The risk-based inspection planning methodology, based on Bayesian decision theory, represents an important tool to identify the suitable strategy to inspect and control the deterioration in structures such as offshore wind...... performance during the life cycle. The deterioration processes, such as fatigue and corrosion, are typically affecting offshore structural systems. This damage decreases the system performance and increases the risk of failure, thus not fulfilling the established safety criteria. Inspection and maintenance...... to their offshore location, no pollution risks and low human risks since they are unmanned. This allows the allocation of lower reliability level compared to e.g. oil & gas installations. With the incursion to water depths between 20 and 50 meters, the use of jacket and tripod structures represents a feasible...

Fatigue Reliability and Calibration of Fatigue Design Factors for Offshore Wind Turbines

DEFF Research Database (Denmark)

Dominguez, Sergio Marquez; Sørensen, John Dalsgaard

2012-01-01

Consequences of failure of offshore wind turbines (OWTs) are in general lower than consequences of failure of, e.g., oil & gas platforms. It is reasonable that lower fatigue design factors can be applied for fatigue design of OWTs when compared to other fixed offshore structures. Calibration...

Outsourcing software development offshore making IT work

CERN Document Server

Gold, Tandy

2004-01-01

THE OFFSHORE IMPERATIVECrunching the Offshore Numbers: What the Financials PortendWelcome to the Definitive Guide on Offshore OutsourcingSetting the Stage: The Compelling Offshore StoryOffshore Outsourcing versus Traditional IT OutsourcingChallenges of Offshore OutsourcingChapter SummaryGetting Started in OffshoreExecutive Support and Communications: The Key to SuccessA Look at an Example of Enlightened Leadership: Handling Employee Impact at a Northeast Utilities CompanyWell-Planned and Executed Communications: A Critical Success Factor for Offshore Program InitiationEstablishing the Offshore

Study on optimized decision-making model of offshore wind power projects investment

Science.gov (United States)

Zhao, Tian; Yang, Shangdong; Gao, Guowei; Ma, Li

2018-02-01

China’s offshore wind energy is of great potential and plays an important role in promoting China’s energy structure adjustment. However, the current development of offshore wind power in China is inadequate, and is much less developed than that of onshore wind power. On the basis of considering all kinds of risks faced by offshore wind power development, an optimized model of offshore wind power investment decision is established in this paper by proposing the risk-benefit assessment method. To prove the practicability of this method in improving the selection of wind power projects, python programming is used to simulate the investment analysis of a large number of projects. Therefore, the paper is dedicated to provide decision-making support for the sound development of offshore wind power industry.

Offshore wind energy prospects

International Nuclear Information System (INIS)

Gaudiosi, Gaetano

1999-01-01

In last two years offshore wind energy is becoming a focal point of national and non national organisations particularly after the limitations of fossil fuel consumption, adopted by many developed countries after Kyoto conference at the end of 1997 on global climate change. North Europe is particularly interested in offshore for the limited land areas still available, due to the intensive use of its territory and its today high wind capacity. Really the total wind capacity in Europe could increase from the 1997 value of 4450 MW up to 40 000 MW within 2010, according the White Paper 1997 of the European Commission; a significant percentage (25%) could be sited offshore up to 10 000 MW, because of close saturation of the land sites at that time. World wind capacity could increase from the 1997 value of 7200 MW up to 60 000 MW within 2010 with a good percentage (20%) offshore 12 000 MW. In last seven years wind capacity in shallow water of coastal areas has reached 34 MW. Five wind farms are functioning in the internal seas of Netherlands, Denmark, Sweden; however such siting is mostly to be considered as semi-offshore condition. Wind farms in real offshore sites, open seas with waves and water depth over 10 m, are now proposed in North Sea at 10-20 km off the coasts of Netherlands, Denmark using large size wind turbine (1-2 MW). In 1997 an offshore proposal was supported in Netherlands by Greenpeace after the OWEMES '97 seminar, held in Italy on offshore wind in the spring 1997. A review is presented in the paper of European offshore wind programs with trends in technology, economics and siting effects. (Author)

Critical success factors for offshoring of enterprise resource planning (ERP implementations

Directory of Open Access Journals (Sweden)

Rajneesh Chauhan

2012-01-01

Full Text Available Background: In recent years, offshoring enterprise resource planning (ERP implementation has been an emerging trend in the field of offshoring information technology (IT. However, both ERP implementations and IT offshoring are fraught with risks, and when both ERP implementation and IT offshoring happen together, the risks become even more pronounced. Therefore, it is important to understand and identify the issues of ERP implementation in an offshoring situation. Objectives: The purpose of this paper is to highlight the key factors that enable successful offshoring ERP implementation from the client and the vendor perspective. Methods/Approach: The paper uses literature as a basis for identifying a critical success factor, data collected through semi-structured interviews with ERP managers at various levels of the subject organizations, and eventually their analysis. Results: The findings of the paper reveal that various factors are critical while implementing offshoring ERP. They include: offshoring partnership, project management, project team composition, people issues, communications and compliance of the onsite team composition. It is also noticed that ten factors are grouped into three categories: the client side, the vendor side, and both. Conclusions: Organizations are currently undertaking or considering the offshoring ERP implementation particularly from India. This paper will enable them to understand the possible challenges and areas of offshoring the ERP implementation program. The value and originality of the paper comes from the fact that up to now, ERP implementation in offshoring has not been comprehensively explored. This research provides a complete understanding of the critical success factors from the client, the vendor or both the client and the vendor perspective. It also enables researchers to analyse ili rethink ili review offshoring in different service areas.

Characteristics of Offshore Hawai';i Island Seismicity and Velocity Structure, including Lo';ihi Submarine Volcano

Science.gov (United States)

Merz, D. K.; Caplan-Auerbach, J.; Thurber, C. H.

2013-12-01

The Island of Hawai';i is home to the most active volcanoes in the Hawaiian Islands. The island's isolated nature, combined with the lack of permanent offshore seismometers, creates difficulties in recording small magnitude earthquakes with accuracy. This background offshore seismicity is crucial in understanding the structure of the lithosphere around the island chain, the stresses on the lithosphere generated by the weight of the islands, and how the volcanoes interact with each other offshore. This study uses the data collected from a 9-month deployment of a temporary ocean bottom seismometer (OBS) network fully surrounding Lo';ihi volcano. This allowed us to widen the aperture of earthquake detection around the Big Island, lower the magnitude detection threshold, and better constrain the hypocentral depths of offshore seismicity that occurs between the OBS network and the Hawaii Volcano Observatory's land based network. Although this study occurred during a time of volcanic quiescence for Lo';ihi, it establishes a basis for background seismicity of the volcano. More than 480 earthquakes were located using the OBS network, incorporating data from the HVO network where possible. Here we present relocated hypocenters using the double-difference earthquake location algorithm HypoDD (Waldhauser & Ellsworth, 2000), as well as tomographic images for a 30 km square area around the summit of Lo';ihi. Illuminated by using the double-difference earthquake location algorithm HypoDD (Waldhauser & Ellsworth, 2000), offshore seismicity during this study is punctuated by events locating in the mantle fault zone 30-50km deep. These events reflect rupture on preexisting faults in the lower lithosphere caused by stresses induced by volcano loading and flexure of the Pacific Plate (Wolfe et al., 2004; Pritchard et al., 2007). Tomography was performed using the double-difference seismic tomography method TomoDD (Zhang & Thurber, 2003) and showed overall velocities to be slower than

Wave scour around structures

DEFF Research Database (Denmark)

Sumer, B. Mutlu; Fredsøe, Jørgen

1999-01-01

This review (of scour around marine structures) is organized in seven main sections: Basic concepts; Tunnel erosion; Two- and three-dimensional scour around pipelines; Scour around piles (slender bodies), including pile groups; Scour around complex structures; Scour around large, vertical cylinders...

Optimierung des Managements der Tragwerksintegritätfür Offshore-Windenergieanlagen

DEFF Research Database (Denmark)

Thöns, Sebastian; Ruecker, Werner; Faber, Michael Havbro

2012-01-01

turbinesupport structures is formulated. The optimal monitoring deci-sion parameters are then assessed utilizing the Bayesian pre-posterior decision theory. As a case study a monitoring systemfor a Multibrid M5000 offshore wind turbine prototype supportstructure is designed and possible reductions of the risks...... concern-ing the characteristics of monitoring techniques and data within the framework of reliability analyses, an approach is introduced for the optimisation of the expected structural integrity management costs by monitoring information. For thisaim, a life cycle cost benefit analysis for offshore wind...

Review of control algorithms for offshore wind turbines

Energy Technology Data Exchange (ETDEWEB)

Spruce, C.J.; Markou, H.; Leithead, W.E.; Dominguez Ruiz, S.

2005-07-01

Innovative turbine control strategies could allow the improvements to cost and performance considered essential to reduce the cost of energy from offshore wind farms around the UK. This project reviewed and investigated the possibility for further development of a power control algorithm originally developed by NEG Micon Rotors Ltd for use with offshore wind turbines in the hope that more advanced algorithms would reduce the loads on, and hence the costs of, components such as the foundation/support structure, tower, blades and bedplate. Three models (simulation model, linearisation of the simulation model and control model) were produced in order to conduct the review. Application of these models produced the conclusion that the size of the latest generation of offshore wind turbines has now reached a level where performance is starting to be constrained by fundamental factors in the dynamics caused by the machine's physical size. It was also concluded that an ideal control strategy could achieve potential cost savings for the tower and support structure of 5-10% of the total cost of the turbine plus support structure. Further work to develop controllers to reduce loads in the tower and support structure is urged. The report considers non-linear simulation, the linear model, the control model, general operation of the controller, the drive train damping filter, torque control, pitch control and advanced algorithms, and makes detailed recommendations for future work.

Abundance of Corals on Offshore Oil and Gas Platforms in the Gulf of Mexico

Science.gov (United States)

Kolian, Stephan R.; Sammarco, Paul W.; Porter, Scott A.

2017-08-01

Scleractinian, octocoral, and antipatharian corals have colonized many of the offshore oil and gas platforms in the northern Gulf of Mexico. We surveyed 25 offshore oil and gas platforms for these cnidarians. Few to no corals were detected on inshore, shallow-water structures at data suggest that the offshore platforms located in waters of >25-30 m in the study area are often colonized by these corals. We recommend that structures located in deeper waters should be surveyed for coral and, if the populations are substantial, consider alternate uses for the retired platforms, and leaving them in place, when feasible.

Measurement and Analysis of Extreme Wave and Ice Actions in the Great Lakes for Offshore Wind Platform Design

Energy Technology Data Exchange (ETDEWEB)

England, Tony [Univ. of Michigan, Ann Arbor, MI (United States). College of Engineering; van Nieuwstadt, Lin [Univ. of Michigan, Ann Arbor, MI (United States). College of Engineering; De Roo, Roger [Univ. of Michigan, Ann Arbor, MI (United States). College of Engineering; Karr, Dale [Univ. of Michigan, Ann Arbor, MI (United States). College of Engineering; Lozenge, David [Univ. of Michigan, Ann Arbor, MI (United States). College of Engineering; Meadows, Guy [Univ. of Michigan, Ann Arbor, MI (United States). College of Engineering

2016-05-30

This project, funded by the Department of Energy as DE-EE0005376, successfully measured wind-driven lake ice forces on an offshore structure in Lake Superior through one of the coldest winters in recent history. While offshore regions of the Great Lakes offer promising opportunities for harvesting wind energy, these massive bodies of freshwater also offer extreme and unique challenges. Among these challenges is the need to anticipate forces exerted on offshore structures by lake ice. The parameters of interest include the frequency, extent, and movement of lake ice, parameters that are routinely monitored via satellite, and ice thickness, a parameter that has been monitored at discrete locations over many years and is routinely modeled. Essential relationships for these data to be of use in the design of offshore structures and the primary objective of this project are measurements of maximum forces that lake ice of known thicknesses might exert on an offshore structure.

Remote sensoring for an offshore windfarm maintenance system

NARCIS (Netherlands)

Leon Morales, C.F.; Malsen, J. van

2011-01-01

In the current offshore wind energy market high cost efficiency is a major factor. While budgets become more limited, the demands for the structures are constantly increasing. Wind turbine park owners (and operators) now request a lifetime of 25 years or more for their off shore structures. The

Dutch offshore skills assessed

Energy Technology Data Exchange (ETDEWEB)

Schaap, P

1988-11-01

The position is described of the different Dutch industries involved in the oil and gas exploitation business in the North Sea. Mentioned are, in the first place, the activities of towing services Smit Tak, and Wijsmuller. A well known drilling contractor is Neddrill. Drilling rigs are often designed in cooperation with consulting engineers firms Protech International, Heerema Engineering, Global Engineering, KTI, Fluor, and Tebodin. Drilling rigs constructors Grootint, Mercon Steel Structures, Heerema Havenbedrijf, HCG, Boele, and IHC have a sound name in the offshore construction scene. Offshore contractors like Heerema, Smit Tak, Volker Stevin and Allseas Engineering should be mentioned too. Special attention is given to the operation of saving drilling rigs in the Ekofisk field. Years of exploitation of oil and gas from this field resulted in subsidence of the sea floor, which endangered the drilling rigs. Hydraudyne designed the hydraulic lifter necessary for this saving operation. Dutch firms in this field have an estimated yearly turnover of Dfl 3 x 10/sup 9/. 6 figs.

Assessing offshore wind potential

International Nuclear Information System (INIS)

Adelaja, Adesoji; McKeown, Charles; Calnin, Benjamin; Hailu, Yohannes

2012-01-01

Quantifying wind potential is a pivotal initial step in developing and articulating a state’s policies and strategies for offshore wind industry development. This is particularly important in the Great Lakes States where lessons from other offshore environments are not directly applicable. This paper presents the framework developed for conducting a preliminary assessment of offshore wind potential. Information on lake bathymetry and wind resources were combined in simulating alternative scenarios of technically feasible turbine construction depths and distance concerns by stakeholders. These yielded estimates of developable offshore wind areas and potential power generation. While concerns about the visibility of turbines from shore reduce the power that can be generated, engineering solutions that increase the depths at which turbines can be sited increase such potential power output. This paper discusses the costs associated with technical limitations on depth and the social costs related to public sentiments about distance from the shoreline, as well as the possible tradeoffs. The results point to a very large untapped energy resource in the Michigan’s Great Lakes, large enough to prompt policy action from the state government. - Highlights: ▶ We build a theoretical framework for modeling offshore wind power production. ▶ Illustration of the impact of technology and social limitations on offshore wind energy development. ▶ Geospatial modeling of the offshore wind potential of the Great Lakes.

Emergency response in the Newfoundland offshore industry

Energy Technology Data Exchange (ETDEWEB)

Dempsey, J. [Cormorant Ltd., St. John' s, NL (Canada)

2006-07-01

This presentation reviewed current offshore oil activities with respect to safety issues regarding year-round marine operations in a harsh environment. Considerable logistics support is required for all offshore activities, including seismic and geotechnical surveys; exploration and production drilling; well testing; subsea construction; on-site production; and, delivery to market. Response to an offshore emergency must address the urgency of the incident along with stakeholder concerns. This presentation described the different types of emergencies and addressed issues regarding contingency planning; preventative measures; response philosophy; response scope; response at site; emergency management; communications links; and, oil spill response. The following current operations were highlighted: ExxonMobil's production drilling from the gravity-based concrete platform at Hibernia; Petro-Canada's production drilling at the Terra Nova FPSO; Husky Energy's production drilling at White Rose; and Chevron Canada's exploration drilling at the Orphan Basin. It was noted that in an emergency situation, the focus is on the welfare of offshore personnel. On an average day, the total offshore population is in the order of 1000 workers, all registered in the Personnel Logistics System which is updated with the departure of every helicopter from St. John's, Newfoundland or from the offshore platform. It is possible to prepare for foreseeable emergency incidents such as fire, explosion or gas leaks; spills to the marine environment; structural damage or collisions; persons lost at sea; helicopter or support vessel accidents; vessel sinking; sabotage; serious injuries or loss of life; severe ice events; and, loss of well control. The establishment of permanent safety zones at the Hibernia, White Rose and Terra Nova production fields are among the preventative measures, along with standby vessels that provide a rescue service for offshore installations

Emergency response in the Newfoundland offshore industry

International Nuclear Information System (INIS)

Dempsey, J.

2006-01-01

This presentation reviewed current offshore oil activities with respect to safety issues regarding year-round marine operations in a harsh environment. Considerable logistics support is required for all offshore activities, including seismic and geotechnical surveys; exploration and production drilling; well testing; subsea construction; on-site production; and, delivery to market. Response to an offshore emergency must address the urgency of the incident along with stakeholder concerns. This presentation described the different types of emergencies and addressed issues regarding contingency planning; preventative measures; response philosophy; response scope; response at site; emergency management; communications links; and, oil spill response. The following current operations were highlighted: ExxonMobil's production drilling from the gravity-based concrete platform at Hibernia; Petro-Canada's production drilling at the Terra Nova FPSO; Husky Energy's production drilling at White Rose; and Chevron Canada's exploration drilling at the Orphan Basin. It was noted that in an emergency situation, the focus is on the welfare of offshore personnel. On an average day, the total offshore population is in the order of 1000 workers, all registered in the Personnel Logistics System which is updated with the departure of every helicopter from St. John's, Newfoundland or from the offshore platform. It is possible to prepare for foreseeable emergency incidents such as fire, explosion or gas leaks; spills to the marine environment; structural damage or collisions; persons lost at sea; helicopter or support vessel accidents; vessel sinking; sabotage; serious injuries or loss of life; severe ice events; and, loss of well control. The establishment of permanent safety zones at the Hibernia, White Rose and Terra Nova production fields are among the preventative measures, along with standby vessels that provide a rescue service for offshore installations. Supply vessels are also

Going for the play: Structural interpretation in offshore Congo

Energy Technology Data Exchange (ETDEWEB)

Platt, N.; Philip, P. (GECO-PRAKLA Exploration Services, Woking (United Kingdom)); Walter, S. (ARK Geophysics Ltd., Milton Keynes, (United Kingdom))

1993-01-01

Looking for new hydrocarbons in frontier areas, geologists and geophysicists use very trick in the book: plate tectonics, magnetic and gravity data, plain old geological horse sense and lots of seismic data. An interpretation team is followed, as they pick their way through a seismic survey shot in offshore Congo, Africa, searching for those areas (the plays) that show the greatest promise. 17 figs., 9 refs.

Wind energy in offshore grids

DEFF Research Database (Denmark)

Schröder, Sascha Thorsten

special characteristics of offshore grids. With an operational real options approach, it is furthermore illustrated how different support schemes and connections to additional countries affect the investment case of an offshore wind farm and the income of the transmission system operator. The investment...... and investment implications under different regulatory frameworks are a hitherto underrepresented research field. They are addressed by this thesis. Offshore grids between several countries combine the absorption of wind energy with international power trading. However, the inclusion into an offshore grid......This cumulative PhD thesis deals with wind integration in offshore grids from an economic point of view. It is composed of a generic part and eight papers. As the topic has mostly been analysed with a focus on topology and technical issues until now, market-operational questions in offshore grids...

Offshore Wind Energy Market Overview (Presentation)

Energy Technology Data Exchange (ETDEWEB)

Baring-Gould, I.

2013-07-01

This presentation describes the current international market conditions regarding offshore wind, including the breakdown of installation costs, how to reduce costs, and the physical siting considerations considered when planning offshore wind construction. The presentation offers several examples of international existing and planned offshore wind farm sites and compares existing international offshore resources with U.S. resources. The presentation covers future offshore wind trends and cites some challenges that the United States must overcome before it will be able to fully develop offshore wind sites.

Long-term Bat Monitoring on Islands, Offshore Structures, and Coastal Sites in the Gulf of Maine, mid-Atlantic, and Great Lakes—Final Report

Energy Technology Data Exchange (ETDEWEB)

Peterson, Trevor [Stantec Consulting Services Inc., Topsham, ME (United States); Pelletier, Steve [Stantec Consulting Services Inc., Topsham, ME (United States); Giovanni, Matt [Stantec Consulting Services Inc., Topsham, ME (United States)

2016-01-15

This report summarizes results of a long-term regional acoustic survey of bat activity at remote islands, offshore structures, and coastal sites in the Gulf of Maine, Great Lakes, and mid-Atlantic coast.

Offshore investments-cui prodis? Schrodinger's cat in offshore financing: Both alive and dead

Directory of Open Access Journals (Sweden)

Stepuk Anna

2014-01-01

Full Text Available Trends of FDI in offshore tax havens were compared to efforts and efficiency of regulatory authorities to prevent money laundering. Based on available data it was stated that current position in offshore FDI stays alive and officially dead at the same time, keeping the balance of interests for the main stakeholders: corporations, authorities and financial institutes support further offshore investments. Analysis based on volumes of trade and financial transactions between offshore centers, developed and developing countries. As a result withdrawal of financial resources from the developing countries degrades social capital funding and supports corruption growth.

Shallow geological environment of Krishna–Godavari offshore ...

Indian Academy of Sciences (India)

Krishna–Godavari (KG) offshore basin (figure 1) began to draw the attention of ... J. Earth Syst. Sci. 123, No. ... are found to occur in different types, i.e., dissemi- nated, nodular ..... domal shaped structures were faulted (figure 7c). Subsequently ...

Managing Information Uncertainty in Wave Height Modeling for the Offshore Structural Analysis through Random Set

Directory of Open Access Journals (Sweden)

Keqin Yan

2017-01-01

Full Text Available This chapter presents a reliability study for an offshore jacket structure with emphasis on the features of nonconventional modeling. Firstly, a random set model is formulated for modeling the random waves in an ocean site. Then, a jacket structure is investigated in a pushover analysis to identify the critical wave direction and key structural elements. This is based on the ultimate base shear strength. The selected probabilistic models are adopted for the important structural members and the wave direction is specified in the weakest direction of the structure for a conservative safety analysis. The wave height model is processed in a P-box format when it is used in the numerical analysis. The models are applied to find the bounds of the failure probabilities for the jacket structure. The propagation of this wave model to the uncertainty in results is investigated in both an interval analysis and Monte Carlo simulation. The results are compared in context of information content and numerical accuracy. Further, the failure probability bounds are compared with the conventional probabilistic approach.

Offshore Wind Energy Ready to Power a Sustainable Europe. Final Report. Concerted Action on Offshore Wind Energy in Europe

International Nuclear Information System (INIS)

2001-12-01

The objective of the project Concerted Action on Offshore Wind Energy in Europe [CA-OWEE] is to define the current state of the art of offshore wind energy in Europe through gathering and evaluation of information from across Europe and to disseminate the resulting knowledge to all interested, in order to help stimulate the development of the industry. The project is being funded by the European Commission and will be completed at the end of 2001. The knowledge gathered will be freely available through an internet site, a workshop and a printed report. This project divides offshore wind energy into five clusters of subjects and reviews the recent history and summarise the current state of affairs, relating to: Cluster 1 offshore technology, of the wind turbines and the support structures, Cluster 2 grid integration, energy supply and financing, Cluster 3 resources and economics, Cluster 4 activities and prospects, Cluster 5 social acceptance, environmental impact and politics. The conclusions from these surveys are then used to define recommendations for the future RTD strategy for Europe. The project's 17 partners come from 13 countries, thus covering the majority of the European Community's coastline. The partners cover a wide range of expertise and include developers, utilities, consultants, research institutes and universities

Offshoring research directions

NARCIS (Netherlands)

Velthuijsen, Hugo

2012-01-01

Outsourcing and offshoring provide companies with ways to achieve their business objectives better or more cost effectively or despite a shortage of specific resources. From a research point of view, outsourcing and offshoring have mostly been studied as something that large companies do, not small

Centrifuge and Numerical Modeling of Monopiles for Offshore Wind Towers Installed in Clay

OpenAIRE

Murali, Madhuri; Grajales, Francisco; Beemer, Ryan D.; Biscontin, Giovanna; Aubeny, Charles

2015-01-01

This is a metadata record relating to an article that cannot be shared due to publisher copyright. Offshore wind power has gained momentum as a means to diversify the world’s energy infrastructure; however, little is still known of the global stiffness behavior of the large diameter low aspect ratio monopiles which have become the foundation of choice for offshore wind towers. Traditionally, offshore foundations have been associated with gravity structures for the oil and gas industry, whi...

National Offshore Wind Energy Grid Interconnection Study

Energy Technology Data Exchange (ETDEWEB)

Daniel, John P. [ABB Inc; Liu, Shu [ABB Inc; Ibanez, Eduardo [National Renewable Energy Laboratory; Pennock, Ken [AWS Truepower; Reed, Greg [University of Pittsburgh; Hanes, Spencer [Duke Energy

2014-07-30

The National Offshore Wind Energy Grid Interconnection Study (NOWEGIS) considers the availability and potential impacts of interconnecting large amounts of offshore wind energy into the transmission system of the lower 48 contiguous United States. A total of 54GW of offshore wind was assumed to be the target for the analyses conducted. A variety of issues are considered including: the anticipated staging of offshore wind; the offshore wind resource availability; offshore wind energy power production profiles; offshore wind variability; present and potential technologies for collection and delivery of offshore wind energy to the onshore grid; potential impacts to existing utility systems most likely to receive large amounts of offshore wind; and regulatory influences on offshore wind development. The technologies considered the reliability of various high-voltage ac (HVAC) and high-voltage dc (HVDC) technology options and configurations. The utility system impacts of GW-scale integration of offshore wind are considered from an operational steady-state perspective and from a regional and national production cost perspective.

Offshore investments: Denmark shows the way

International Nuclear Information System (INIS)

Anon.

1998-01-01

This article presents an overview of the use of wind power in Denmark and discusses the tremendous growth in the manufacture of wind turbines since 1981 with Denmark holding some 60% of the worlds' wind turbine market. The move to offshore wind farms is explained in terms of the shortage of land and the quality of the offshore wind, and details of the Tuno Knob pilot offshore wind farm are given. Offshore wind power in Europe, the challenges to offshore operations, the costs involved, environmental effects of the use of offshore wind, and the growing amount of wind power capacity are discussed

Study of a new hydraulic pumping unit based on the offshore platform

OpenAIRE

Yu, Yanqun; Chang, Zongyu; Qi, Yaoguang; Xue, Xin; Zhao, Jiannan

2017-01-01

This article introduces a new technology about a rod pumping in the offshore platform according to the demand of offshore heavy oil thermal recovery and the production of stripper well, analyzes the research status of hydraulic pumping unit at home and abroad, and designs a new kind of miniature hydraulic pumping unit with long-stroke, low pumping speed and compact structure to resolve the problem of space limitation. The article also describes the whole structure and the working principle of...

Global offshore pipeline markets

International Nuclear Information System (INIS)

Knight, R.; Parsons, B.

2001-01-01

In this article, two experts forecast a recovery in the offshore pipeline market followed by accelerating growth. A number of clearly definable macro trends are affecting the world offshore oil and gas industry and will be of considerable significance to the offshore pipelines industry. The authors' view is of markets that show every chance of enjoying long-term growth prospects driven by the fundamentals of a continuing increase in demand for offshore oil and gas. The offshore industry however has a highly cyclical nature, due to the impact of variations in oil and gas prices and the differing state of maturity of individual regions. Therefore those companies that are able to offer the widest range of pipe types and diameters and methods of installation across the greatest range of geographic markets are likely to prosper most. Thus, this continues to be a market best suited to those able to operate on a global scale and make a corporate commitment measured in decades

Decommissioning and abandonment of offshore installations

International Nuclear Information System (INIS)

Side, J.C.

1992-01-01

To the onlooker surprising little thought was given at the project planning stage to the fate of offshore facilities once their production lifetimes had come to an end. Throughout the 1970s at least, international law required the complete removal of all structures and installations one disused or abandoned. Fishermen's organisations were led to believe that such installations would be entirely removed yet many of the designs of these show that removal was not much in the minds of the engineers or project management during the design stages. Changes in the text of the United Nations' Convention on the Law of the Sea and (by their widespread legal adoption) in customary international law may now permit partial removal of installations subject to important safeguards for navigation, the environment and other users of the sea. Of the North Sea states at least one has adopted policies that will minimise the cost associated with offshore decommissioning and abandonment and both the UK and Norway are adopting legislation which will provide for a case by case approach to the decommissioning and abandonment of offshore facilities and allow partial removal options. There has thus been a recent and significant change in approach to the abandonment of offshore oil and gas installations. This chapter reviews the development of abandonment laws and policies, outlines the available removal options, and provides a consideration of the environmental and fishery implications of these for the North Sea. (Author)

Panorama 2012 - Offshore hydrocarbons

International Nuclear Information System (INIS)

Serbutoviez, Sylvain

2011-12-01

Technological progress is enabling production from offshore oil and gas fields at increasingly ambitious depths (3, 000 metres). Investment in offshore production is running at around $100 billion per year, accounting for one-fifth of all investment in oil exploration and development worldwide. However, the global economic crisis that broke at the end of 2008 and the accident involving the Macondo well temporarily disrupted the race to deep offshore technology. (author)

Fluid-structure interaction simulation of floating structures interacting with complex, large-scale ocean waves and atmospheric turbulence with application to floating offshore wind turbines

Science.gov (United States)

Calderer, Antoni; Guo, Xin; Shen, Lian; Sotiropoulos, Fotis

2018-02-01

We develop a numerical method for simulating coupled interactions of complex floating structures with large-scale ocean waves and atmospheric turbulence. We employ an efficient large-scale model to develop offshore wind and wave environmental conditions, which are then incorporated into a high resolution two-phase flow solver with fluid-structure interaction (FSI). The large-scale wind-wave interaction model is based on a two-fluid dynamically-coupled approach that employs a high-order spectral method for simulating the water motion and a viscous solver with undulatory boundaries for the air motion. The two-phase flow FSI solver is based on the level set method and is capable of simulating the coupled dynamic interaction of arbitrarily complex bodies with airflow and waves. The large-scale wave field solver is coupled with the near-field FSI solver with a one-way coupling approach by feeding into the latter waves via a pressure-forcing method combined with the level set method. We validate the model for both simple wave trains and three-dimensional directional waves and compare the results with experimental and theoretical solutions. Finally, we demonstrate the capabilities of the new computational framework by carrying out large-eddy simulation of a floating offshore wind turbine interacting with realistic ocean wind and waves.

Multiple tuned mass damper based vibration mitigation of offshore wind turbine considering soil-structure interaction

Science.gov (United States)

Hussan, Mosaruf; Sharmin, Faria; Kim, Dookie

2017-08-01

The dynamics of jacket supported offshore wind turbine (OWT) in earthquake environment is one of the progressing focuses in the renewable energy field. Soil-structure interaction (SSI) is a fundamental principle to analyze stability and safety of the structure. This study focuses on the performance of the multiple tuned mass damper (MTMD) in minimizing the dynamic responses of the structures objected to seismic loads combined with static wind and wave loads. Response surface methodology (RSM) has been applied to design the MTMD parameters. The analyses have been performed under two different boundary conditions: fixed base (without SSI) and flexible base (with SSI). Two vibration modes of the structure have been suppressed by multi-mode vibration control principle in both cases. The effectiveness of the MTMD in reducing the dynamic response of the structure is presented. The dynamic SSI plays an important role in the seismic behavior of the jacket supported OWT, especially resting on the soft soil deposit. Finally, it shows that excluding the SSI effect could be the reason of overestimating the MTMD performance.

One-Way Fluid-Structure Interaction Simulation of an Offshore Wind Turbine

Directory of Open Access Journals (Sweden)

Zhi-Kui Wang

2014-07-01

Full Text Available The Fluid-Structure Interaction (FSI has gained great interest of scholars recently, meanwhile, extensive studies have been conducted by the virtue of numerical methods which have been implemented on wind turbine models. The blades of a wind turbine have been gained a deep insight into the FSI analyses, however, few studies have been conducted on the tower and nacelle, which are key components of the wind turbine, using this method. We performed the one-way FSI analysis on a 2-MW offshore wind turbine, using the Finite Volume Method (FVM with ANSYS CFX solver and the RNG k-ε turbulence model, to achieve a comprehensive cognition of it. The grid convergence was studied and verified in this study, and the torque value is chosen to determine the optimal case. The superior case, which was chosen to conduct the FSI analysis, with a relative error is only 2.15%, thus, the accuracy of results is credible.

Structural inheritance and coastal geomorphology in SW Brittany, France: An onshore/offshore integrated approach

Science.gov (United States)

Raimbault, Céline; Duperret, Anne; Le Gall, Bernard; Authemayou, Christine

2018-04-01

The Variscan crystalline basement exposed along the SW Brittany coast recorded extensive long-term planation processes during Mesozoic times. Detailed onshore-offshore mapping (600 km2) in the Penmarc'h-Concarneau granitic coastal area reveals a km-scale, deeply fractured submarine rocky shelf. High-resolution offshore imagery (bathymetry and seismic reflection dataset), combined to structural field investigations, on these surfaces allow us to identify a preserved network of both ductile and brittle structures. The inherited fault pattern is dominated by the N160°E-trending and long-lived Concarneau-Toulven fault zone (CTFS) that separates two distinct morphostructural blocks, and strongly influences the seaward limit of the Concarneau submarine rocky shelf, as well as the linear coastline of the Concarneau embayment. The structural imprint of the CTFS decreases progressively westwards with respect to a composite network of large-scale N50°E- and N140°E-oriented faults bounding the seaward edge of the Penmarc'h rocky shelf. The latter in turn splits into three large-scale blocks along N50°E- (La Torche Fault - LTF), N140°E- (Saint Guénolé Fault - SGF) and N160°E-trending normal faults. The morphostructural evolutionary model applied here to the Penmarc'h-Concarneau granitic coastal area resulted from the combined effects of structural Variscan inheritance and post-Variscan tectonics. Paleo-stress analysis of striated fault planes indicates three main Cenozoic tectonic events, inferred to have operated from Eocene to post-Oligocene times. The 3D-architecture of the Concarneau embayment, as a rocky shelf partially sealed with quaternary sediments, chiefly resulted from the reactivation of the CTFS during Eocene and Oligocene times. Further west, the surface of the Penmarc'h rocky shelf was tilted southeastward by the brittle reactivation of the LTF, and dissected by a horst-graben network post-Oligocene in age. The present-day morphology of the Penmarc'h and

Offshore industry: medical emergency response in the offshore oil and gas industry.

Science.gov (United States)

Ponsonby, Will; Mika, Frano; Irons, Greg

2009-08-01

The hunt for oil and gas has taken workers into new more distant locations including those offshore. The remoteness of the offshore platforms and vessels coupled with the potential risk of being cut off by bad weather presents particular challenges for medical emergency response (MER). Firstly to define the challenges for MER in terms of locations, population and epidemiology of injuries and illnesses in the offshore environment. Secondly to give examples of legal requirements and industry standards to manage MER. Thirdly to look at existing and emerging practice to manage these challenges. A review of published literature was supplemented with a summary of current practice in the industry. Medical professionals (medics) working offshore on installations and vessels are primarily responsible for the medical care of the workers. The medics have clinics with suitable medical equipment for managing emergencies as well as providing limited primary care. Some countries have legislation that stipulate minimum requirements. Where there is no national legislation, industry and company guidance is used to define the MER standards. Supervision of the offshore medics is often provided by doctors on shore via radio and phone links. These methods of communication are now being augmented with more sophisticated telemedicine solutions such as the Internet and live video links. These newer solutions allow for prompt high-quality care and provide the scope for a variety of new treatment options to be available for the offshore workforce.

Uncovering the Hidden Costs of Offshoring

DEFF Research Database (Denmark)

Larsen, Marcus M.; Manning, Stephan; Pedersen, Torben

2013-01-01

This study investigates estimation errors due to hidden costs—the costs of implementation that are neglected in strategic decision-making processes—in the context of services offshoring. Based on data from the Offshoring Research Network, we find that decision makers are more likely to make cost......-estimation errors given increasing configuration and task complexity in captive offshoring and offshore outsourcing, respectively. Moreover, we show that experience and a strong orientation toward organizational design in the offshoring strategy reduce the cost-estimation errors that follow from complexity. Our...

Brief communication: Structural monitoring for lifetime extension of offshore wind monopiles: can strain measurements at one level tell us everything?

Directory of Open Access Journals (Sweden)

L. Ziegler

2017-09-01

Full Text Available Operators need accurate knowledge on structural reserves to decide about lifetime extension of offshore wind turbines. Load monitoring enables us to directly compare design loads with real loading histories of the support structure in order to calculate its remaining useful lifetime. Monitoring of every hot spot is technically and financially not feasible. This paper presents a novel idea for load monitoring of monopiles. It requires strain measurements at only one level convenient for sensor installation, such as tower bottom. Measurements are converted into damage equivalent loads for 10 min time intervals. Damage equivalent loads are extrapolated to other locations of the structure with a simulation model and statistical algorithm. For this, structural loads at all locations of the monopile are calculated with aero-hydro-elastic software and updated finite element models. Damage equivalent loads at unmeasured locations are predicted from the simulation results with a k-nearest neighbor regression algorithm. The extrapolation was tested with numerical simulations of an 8 MW offshore wind turbine. Results show that damage can be predicted with an error of 1–3 % if this is done conditional on mean wind speed, which is very promising. The load monitoring concept is simple, cheap and easy to implement. This makes it ideal for making decisions on lifetime extension of monopiles.

Tidal influence on offshore wind fields and resource predictions[Efficient Development of Offshore Windfarms

Energy Technology Data Exchange (ETDEWEB)

Khan, D. [Entec UK Ltd., Doherty Innovation Centre, Penicuik (United Kingdom); Infield, D. [Loughborough Univ., Centre for Renewable Energy Systems Tecnology, Loughborough (United Kingdom)

2002-03-01

The rise and fall of the sea surface due to tides effectively moves an offshore wind turbine hub through the wind shear profile. This effect is quantified using measured data from 3 offshore UK sites. Statistical evidence of the influence of tide on mean wind speed and turbulence is presented. The implications of this effect for predicting offshore wind resource are outlined. (au)

New offshore platform in the Mexican Gulf

Energy Technology Data Exchange (ETDEWEB)

Beisel, T.

1982-04-01

After a construction period of only 10 months, the second steel Offshore platform was recently completed in the Mexican Gulf. The pattern for this structure was the Cognac platform. The erection of the new platform, called the 'Cerveza' platform, is described in the article.

Nose micro-blowing for asymmetric vortices control on blunt-nose slender body at high angle of attack

Directory of Open Access Journals (Sweden)

Lei Wang

2017-11-01

Full Text Available The asymmetric vortices over blunt-nose slender body at high angles of attack result in random side force. In this paper, a nose micro-blowing technology is used to control the asymmetric flow. Pressure measurement and particle image velocimetry (PIV experiments are conducted in a low-speed wind tunnel to research effects of jet flow rate on asymmetric vortices over blunt-nose slender body. The angle of attack of the model is fixed at 50° and the Reynolds number for the experiments is 1.6×10 5 based on diameter of aftbody. A blow hole (5 mm in diameter on the nose is processed at circumferential angle θb= 90° and meridian angle γb= 20° with jet momentum ratio Cμ ranging from 5.30×10-7 to 1.19×10−4. Tests are made under two kinds of perturbations. One is called single perturbation with only blow hole and the other is called combined perturbation consists of blow hole and additional granules set on nose. The results show that whether the model has the single perturbation or the combined one, the sectional side force of x/D = 3 varies in the same direction with the increasement of Cμ and remains stable when Cμ is greater than 3.29×10−6. But the stable force values are different according to various perturbations. The fact proves that the size and direction of the side force of blunt-nose slender body can be controlled by the nose micro-blowing.

Co-sourcing in software development offshoring

DEFF Research Database (Denmark)

Schlichter, Bjarne Rerup; Persson, John Stouby

2013-01-01

Software development projects are increasingly geographical distributed with offshoring, which introduce complex risks that can lead to project failure. Co-sourcing is a highly integrative and cohesive approach, seen successful, to software development offshoring. However, research of how co......-sourcing shapes the perception and alleviation of common offshoring risks is limited. We present a case study of how a certified CMMI-level 5 Danish software supplier approaches these risks in offshore co-sourcing. The paper explains how common offshoring risks are perceived and alleviated when adopting the co...

Mixing by turbulent buoyant jets in slender containers

International Nuclear Information System (INIS)

Voropayev, S.I.; Nath, C.; Fernando, H.J.S.

2012-01-01

A turbulent buoyant jet injected vertically into a slender cylinder containing a stratified fluid is investigated experimentally. The working fluid is water, and salt is used to change its density to obtain either a positively or negatively buoyant jet. The interest is the vertical density distribution in container and its dependence on time and other parameters. For each case (lighter or heavier jet) the experimental data could be collapsed into a ‘universal’ time dependent behavior, when properly non-dimensionalized. A theoretical model is advanced to explain the results. Possible applications include refilling of crude oil into U.S. strategic petroleum reserves caverns. -- Highlights: ► We addresses a critical issue on refill of Strategic Petroleum Reserves. ► We conduct experiments on negatively/positively buoyant turbulent jets in long cavern. ► Basing on results of experiments we developed theoretical model for refill operations.

Some new offshore technologic trends and their possible influence on the world gas supply structure; Quelques nouvelles tendances technologiques en offshore et leur influence possible sur la structure de la disponibilite mondiale de gaz

Energy Technology Data Exchange (ETDEWEB)

Yakushev, V.S. [VNIIGAZ, OAO Gazprom (Russian Federation)

2000-07-01

According to Global Energy Scenarios (GES) role of natural gas as primary energy source in 21. century will grow considerably. In the same time gas industry has to response 3 challenges: environmental, technological and political to make these scenarios real. Development of new technological systems uniting offshore gas production, shuttle transport by tankers and CO{sub 2} sequestration looks like the most optimum way of these problems solution. Some new current technological trends are shown and the most probable technologic concept on gas production from deep and ultra-deep waters is suggested. Probable changes in the world gas supply structure caused by these systems application are discussed. (author)

Design off-shore wind climate

Energy Technology Data Exchange (ETDEWEB)

Larsen, G C; Joergensen, H E [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark)

1999-03-01

Specific recommendations of off-shore turbulence intensities, applicable for design purposes, are lacking in the present IEC-code. The present off-shore wind climate analysis presents the distribution of the turbulence standard deviation around the mean turbulence standard deviation, conditioned on the mean wind speed. Measured distributions, based on a huge amount of measuring data from two shallow water off-shore sites, are parameterized by fitting to a three parameter Weibull distribution. Combining a simple heuristic load model with the parameterized probability density functions of the turbulence standard deviations, an empirical off-shore design turbulence intensity is evaluated that in average yields the same fatigue damage as the distributed turbulence intensity. The proposed off-shore design turbulence intensity is, within the IEC code framework, applicable for extreme as well as for fatigue load determination. (au)

OFFSHORING FOR SUSTAINABLE VALUE MANAGEMENT

Directory of Open Access Journals (Sweden)

Thaddeus Oforegbunam Ebiringa

2014-05-01

Full Text Available This paper evaluates offshoring as a strategic value management initiative using Cadbury Nigeria Plc as a case study. Through offshoring risks associated with inventory holding are hedged. A comparative analysis of in-house and offshored cost profiles as well as critical risk factors that affect firm value are evaluated. The result shows that offshoring led to immediate costs saving, freeing of funds previously held in inventory for other working capital investments as well as profitability for vendors. However, aside financial benefits to partners, it leads to increased stakeholders awareness, shared values, partnerships, teamwork and risk mitigation. It therefore follows that for sustainability of financial benefits of offshoring, concerted effort must be made by partners to ensure that critical drivers of value management are not compromised.

Lake Michigan Offshore Wind Feasibility Assessment

Energy Technology Data Exchange (ETDEWEB)

Boezaart, Arnold [GVSU; Edmonson, James [GVSU; Standridge, Charles [GVSU; Pervez, Nahid [GVSU; Desai, Neel [University of Michigan; Williams, Bruce [University of Delaware; Clark, Aaron [GVSU; Zeitler, David [GVSU; Kendall, Scott [GVSU; Biddanda, Bopi [GVSU; Steinman, Alan [GVSU; Klatt, Brian [Michigan State University; Gehring, J. L. [Michigan State University; Walter, K. [Michigan State University; Nordman, Erik E. [GVSU

2014-06-30

project including to: 1) test and validate floating LIDAR technology; 2) collect and access offshore wind data; 3) detect and measure bird and bat activity over Lake Michigan; 4) conduct an over water sound propagation study; 5) prepare and offer a college course on offshore energy, and; 6) collect other environmental, bathometric, and atmospheric data. Desk-top research was performed to select anchorage sites and to secure permits to deploy the buoy. The project also collected and analyzed data essential to wind industry investment decision-making including: deploying highly mobile floating equipment to gather offshore wind data; correlating offshore wind data with conventional on-shore MET tower data; and performing studies that can contribute to the advancement and deployment of offshore wind technologies. Related activities included: • Siting, permitting, and deploying an offshore floating MET facility; • Validating the accuracy of floating LWS using near shoreline cup anemometer MET instruments; • Assessment of laser pulse technology (LIDAR) capability to establish hub height measurement of wind conditions at multiple locations on Lake Michigan; • Utilizing an extended-season (9-10 month) strategy to collect hub height wind data and weather conditions on Lake Michigan; • Investigation of technology best suited for wireless data transmission from distant offshore structures; • Conducting field-validated sound propagation study for a hypothetical offshore wind farm from shoreline locations; • Identifying the presence or absence of bird and bat species near wind assessment facilities; • Identifying the presence or absence of benthic and pelagic species near wind assessment facilities; All proposed project activities were completed with the following major findings: • Floating Laser Wind Sensors are capable of high quality measurement and recordings of wind resources. The WindSentinel presented no significant operational or statistical limitations in

Optimierung des Managements der Tragwerksintegrität für Offshore-Windenergieanlagen

DEFF Research Database (Denmark)

Thoens, Sebastian; Faber, Michael Havbro; Ruecker, Werner

2012-01-01

by monitoring information. For this aim, a life cycle cost benefit analysis for offshore wind turbine support structures is formulated. The optimal monitoring decision parameters are then assessed utilizing the Bayesian preposterior decision theory. As a case study a monitoring system for a Multibrid M5000...... cycle by compliance with the target reliabilities. Building upon research results concerning the characteristics of monitoring techniques and data within the framework of reliability analyses, an approach is introduced for the optimisation of the expected structural integrity management costs...... offshore wind turbine prototype support structure is designed and possible reductions of the risks and expected costs are quantified....

Welding in hostile environment for nuclear and offshore industry

International Nuclear Information System (INIS)

Delauze, H.G.

1990-01-01

The paper reviews recent developments of duplex stainless steel and clad pipe welding and under water welding for offshore structures and for reactor fuel storage pool and remote automatic dry welding [fr

THE USE OF OFFSHORE JURISDICTIONS IN INTERNATIONAL FINANCIAL FITTINGS

Directory of Open Access Journals (Sweden)

DANIELA RADU

2012-05-01

Full Text Available Essential legal and financial Structures, sometimes complex, had until recently been small and medium entrepreneurs away from the use of offshore jurisdictions, but the constraints of increasingly heavy taxation of excessive in certain States, you push even those with limited resources to use in these jurisdictions to protect revenue. The purpose of this research is to analyze the offshore jurisdictions in order to determine the possibilities of useof their disadvantages in order to improve measures to combat tax evasion, as well as for the use of their advantages in order to reduce illegal migration and regular employment of capital through the analysis of specific cases of the use of offshore jurisdictions – Case Frabklin Jurado, The Bank of Commerce and Credit InternationalAmerican Express Bank International. Scientific novelty and originality of the investigation consists of:-the identification on the basis of international practice, some offshore jurisdictions specific items in order to reflect their fiscal policies (trade and investment, etc.-analysis of cases of the use of offshore jurisdictions in international financial fittings (such as the Bank of Credit and Commerce International; Franklin Jurado; American Express Bank International,-identification of the impact paradisurilor tax and offshore financial centres of the world economy– revealing secret financial transactions carried out within the framework of ofssore, research instruments jurisdictions and management techniques of cadrulacestor tax jurisdictions.It is interesting to be seen through the prism of analysis of economic-fiscal financiare if a competition is beneficial or not for the welfare of States and to what extent this competition will have a say in future developments and tax paradisurilor finanaciare offshore centres. In conclusion, I appreciate that in order to survive successfully in the global economy of the future, offshoreJurisdictions should promote a

Panorama 2013 - Offshore wind power

International Nuclear Information System (INIS)

Vinot, Simon

2012-10-01

While onshore wind power is already a well-developed global industry, offshore wind power is still in the consolidation and globalization phase. The most mature of marine renewable energies is beginning to venture off the European coast and even to other continents, driven by public policies and the ever increasing number of players joining this promising market, which should evolve into deeper waters thanks to floating structures. (author)

Study of environmental concerns: offshore oil and gas drilling and production

Energy Technology Data Exchange (ETDEWEB)

Baker, R

1978-01-01

Material on the environmental concerns associated with offshore drilling and production activities has been synthesized with Department of Fisheries and Environment files on specific projects, these being the primary information source. Recommendations to resolve these concerns have also been provided. Most of the environmental concerns identified in this study are traceable to specific weaknesses in offshore drilling and production procedures and management systems. Hardware weaknesses are seldom of central importance. Areas of concern include the gradual deposition of pollutants from rigs, underwater pipelines and onshore ancillary structures, and the quality of the following: action plans to deal with oil spills, standards for safety and anti-pollution equipment, information provided on the environmental hazards in offshore drilling and production areas, environmental impact assessments, and communication links between those having environmental concerns and expertise (including the public-at-large) and those who make the decisions regarding offshore oil and gas development.

Metocean Data Needs Assessment for U.S. Offshore Wind Energy

Energy Technology Data Exchange (ETDEWEB)

Bailey, Bruce H. [AWS Truepower LLC., Albany, NY (United States); Filippelli, Matthew [AWS Truepower LLC., Albany, NY (United States); Baker, Matthew [AWS Truepower LLC., Albany, NY (United States)

2015-01-01

A potential barrier to developing offshore wind energy in the United States is the general lack of accurate information in most offshore areas about the wind resource characteristics and external metocean design conditions at the heights and depths relevant to wind turbines and their associated structures and components. Knowledge of these conditions enables specification of the appropriate design basis for wind turbine structures and components so they can withstand the loads expected over a project’s lifetime. Human safety, vessel navigation, and project construction and maintenance activities are equally tied to the metocean environment. Currently, metocean data is sparse in potential development areas and even when available, does not include the detail or quality required to make informed decisions.

Maintenance Planning of Offshore Wind Turbine using Condition Monitoring Information

DEFF Research Database (Denmark)

Ramírez, José G. Rangel; Sørensen, John Dalsgaard

2009-01-01

Deterioration processes such as fatigue and corrosion are typically affecting offshore structures. To "control" this deterioration, inspection and maintenance activities are developed. Probabilistic methodologies represent an important tool to identify the suitable strategy to inspect and control...... the deterioration in structures such as offshore wind turbines (OWT). Besides these methods, the integration of condition monitoring information (CMI) can optimize the mitigation activities as an updating tool. In this paper, a framework for risk-based inspection and maintenance planning (RBI) is applied for OWT....... With the integration of CMI by means Bayesian inference, a slightly change of first inspection times are coming up, influenced by the reduction of the uncertainty and harsher or milder external agents....

Wind turbine structural dynamics - a review of the principles for modern power generation, onshore and offshore

Energy Technology Data Exchange (ETDEWEB)

Tempel, J. van der; Molenaar, D.-P.

2002-07-01

Wind turbines for electricity production have two seemingly opposing constraints; they need to be structural secure yet of low cost. To meet the first constraint, it would be an obvious choice to design a stiff structure of consequently large mass but this would drive up the cost. By reducing the mass a more cost effective turbine can be realized. However, such lightweight structures are by definition more flexible. To design a cost effective flexible system, thorough understanding of the dynamics is essential. This paper reviews the theoretical basics of the dynamic design options and applies these to realistic situations, including offshore machines under wave action. The wind energy converter and the support structure form an integrated dynamic system that must be developed in mutual interdependency and close co-operation. This paper provides a contribution to this integration process by extending the design approach initiated in the Opti-OW ECS study and the work of Kuhn. (author)

Offshore oil and gas and offshore wind power - different in terms of safety.?; Offshore Oel and Gas und Offshore Wind - mit Sicherheit ''anders''.?

Energy Technology Data Exchange (ETDEWEB)

Weise, F.; Tatulinski, M. [DNV GL - Oil and Gas Germany, Hamburg (Germany)

2014-07-01

Safety standards in the oil and gas industry have risen to a high level over the past decades, driven in part by momentous accidents. Furthermore, an expanded framework has recently been defined through the new EU Offshore Safety Directive, which in Germany is still in the process of its transposition into national law. The installation of offshore wind farms in the North and Baltic Sea has within the shortest of time brought forth an entirely new branch of industry, most of whose players have no significant experience with offshore operations. One of the greatest challenges is the working environment, which is being approached in different ways by those involved. The supervisory authorities responsible are only just beginning to develop the competence required for their tasks, with the effect that regulations pertaining to onshore operations are often simply adopted as they are. This is in some cases impacting on the oil and gas industry, as is discussed in the present lecture. [German] Die Oel und Gas Industrie hat in den vergangen Jahrzehnten einen hohen Sicherheitsstandard entwickelt, teilweise getrieben durch signifikante Unfallereignisse. Aktuell wurde zudem mit der neuen EU-Offshore Richtlinie ein erweiterter Rahmen definiert, der sich in Deutschland noch in der gesetzgeberischen Umsetzung befindet. Durch die Installation von Offshore-Windparks in der Nord- und Ostsee ist innerhalb kuerzester Zeit zusaetzlich ein neuer Industriebereich entstanden, dessen Marktteilnehmer mehrheitlich nicht ueber signifikante Offshore-Erfahrung verfuegen. Insbesondere das Arbeitsumfeld stellt dabei eine Herausforderung dar, die von den Beteiligten unterschiedlich geloest wird. Ferner beginnen auch die verantwortlichen Aufsichtsbehoerden erst mit dem Aufbau entsprechender Kompetenzen, so dass vielfach auch Regelungen aus dem Onshore-Bereich uebertragen werden. Dies fuehrt teilweise zu Auswirkungen auf die Oel- und Gasindustrie, die im Rahmen dieses Vortrages diskutiert werden.

Effective Method for Determining Environmental Loads on Supporting Structures for Offshore Wind Turbines

Directory of Open Access Journals (Sweden)

Dymarski Paweł

2016-01-01

Full Text Available This paper presents a description of an effective method for determining loads due to waves and current acting on the supporting structures of the offshore wind turbines. This method is dedicated to the structures consisting of the cylindrical or conical elements as well as (truncates pyramids of polygon with a large number of sides (8 or more. The presented computational method is based on the Morison equation, which was originally developed only for cylindrically shaped structures. The new algorithm shown here uses the coefficients of inertia and drag forces that were calculated for non-cylindrical shapes. The analysed structure consists of segments which are truncated pyramids on the basis of a hex decagon. The inertia coefficients, CM, and drag coefficients, CD, were determined using RANSE-CFD calculations. The CFD simulations were performed for a specific range of variation of the period, and for a certain range of amplitudes of the velocity. In addition, the analysis of influence of the surface roughness on the inertia and drag coefficients was performed. In the next step, the computations of sea wave, current and wind load on supporting structure for the fifty-year storm were carried out. The simulations were performed in the time domain and as a result the function of forces distribution along the construction elements was obtained. The most unfavourable distribution of forces will be used, to analyse the strength of the structure, as the design load.

Dutch offshore suppliers in confident mood

International Nuclear Information System (INIS)

Beudel, M.

1998-01-01

A series of linked articles discusses the current state of the Netherland's offshore industry. Reduced taxes, and availability of exploration licenses has meant that explorers and producers are drawn to the small size, but frequent yield explorations on Holland's continental shelf. The excellent operation record of Rotterdam's Verolme Botlek yard; for repair and maintenance of offshore platforms and associated plant, is explored as the facility plans to diversify into newbuilding. The construction of an offshore basin designed for the hydrodynamic testing of offshore plant intended for deepwater use is described. The Netherlands maritime research institute (Marin) aims to stay at the forefront of offshore research and development with this new facility. Other articles cover pipe tensioning, new large linear winches and innovations in offshore drilling and production. (UK)

Concurrent engineering solution for the design of ship and offshore bracket parts and fabrication process

Directory of Open Access Journals (Sweden)

Tae-Won Kim

2013-09-01

Full Text Available Brackets in ships and offshore structures are added structures that can endure stress concentrations. In this study, a concurrent engineering solution was proposed, and a high strength low carbon cast steel alloy applicable to offshore structures was designed and developed. The yield strength and ultimate tensile strength of the designed steel were 480 and 600 MPa, respectively. The carbon equivalent of the steel was 0.446 with a weld crack susceptibility index of 0.219. The optimal structural design of the brackets for offshore structures was evaluated using ANSYS commercial software. The possibility of replacing an assembly of conventional built-up brackets with a single casting bulb bracket was verified. The casting process was simulated using MAGMAsoft commercial software, and a casting fabrication process was designed. For the proposed bulb bracket, it was possible to reduce the size and weight by approximately 30% and 50%, respectively, compared to the conventional type of bracket.

CEPF Western Ghats Special Series: Moolah, misfortune or spinsterhood? The plight of Slender Loris Loris lydekkerianus in southern India

Directory of Open Access Journals (Sweden)

A. Kanagavel

2013-01-01

Full Text Available In this communication, we document the local knowledge, attitudes and perceptions of slender lorises among the indigenous Kani community in the southern Western Ghats; document new records of Loris lydekkerianus lydekkerianus in the Agasthyamalai Hills; and discuss in detail a poorly known threat to these primates. Although not kept as pets due to their physical appearance, and belief that they would bring bad luck, the Kani community however captured slender lorises for wildlife photographers. Similar instances of loris abuse in various parts of south India were revealed upon analyzing photographs from a popular internet-based wildlife photography site. We recommend that strict guidelines be formulated for photographing lorises, and suggest that novel and ethical tourism initiatives be set up involving local communities to cater to wildlife photographers and tourists.

Influence of Nonlinear Irregular Waves on the Fatigue Loads of an Offshore Wind Turbine

NARCIS (Netherlands)

Van der Meulen, M.B.; Ashuri, T.; Van Bussel, G.J.W.; Molenaar, D.P.

2012-01-01

In order to make offshore wind power a cost effective solution that can compete with the traditional fossil energy sources, cost reductions on the expensive offshore support structures are required. One way to achieve this, is to reduce the uncertainty in wave load calculations by using a more

Optimization of monopiles for offshore wind turbines.

Science.gov (United States)

Kallehave, Dan; Byrne, Byron W; LeBlanc Thilsted, Christian; Mikkelsen, Kristian Kousgaard

2015-02-28

The offshore wind industry currently relies on subsidy schemes to be competitive with fossil-fuel-based energy sources. For the wind industry to survive, it is vital that costs are significantly reduced for future projects. This can be partly achieved by introducing new technologies and partly through optimization of existing technologies and design methods. One of the areas where costs can be reduced is in the support structure, where better designs, cheaper fabrication and quicker installation might all be possible. The prevailing support structure design is the monopile structure, where the simple design is well suited to mass-fabrication, and the installation approach, based on conventional impact driving, is relatively low-risk and robust for most soil conditions. The range of application of the monopile for future wind farms can be extended by using more accurate engineering design methods, specifically tailored to offshore wind industry design. This paper describes how state-of-the-art optimization approaches are applied to the design of current wind farms and monopile support structures and identifies the main drivers where more accurate engineering methods could impact on a next generation of highly optimized monopiles. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Structural steels for fixed offshore platforms: technical challenges at the Brazilian national supply chain; Acos estruturais para plataformas fixas offshore: desafios tecnicos junto a cadeia de suprimentos nacional brasileira

Energy Technology Data Exchange (ETDEWEB)

Castro, Fabio Modesti Orsini de [Promon Engenharia Ltda., Rio de Janeiro, RJ (Brazil)

2012-07-01

This paper presents the main technical requirements for structural steel applied to the construction of bottom fixed offshore platforms, based on the most widely adopted and recognized actual standards. The mechanical properties and lab tests necessary to fulfill the Risk Management and E and P companies requirements are presented aiming to build the theoretical bases necessary for the engineering design of projects of this kind. The main types of steel available in the national market are presented at the end, giving an overall look at the Brazilian steel supply chain. (author)

Offshore wind power experiences, potential and key issues for deployment

Energy Technology Data Exchange (ETDEWEB)

Lemming, J.; Morthorst, P.E.; Clausen, Niels-Erik

2009-01-15

Wind power has been growing at spectacular rates. Today it is the largest non-hydro renewable power technology. Worldwide there is 74 GW of installed capacity which is 1.7% of power generation capacity and in 2006 it accounted for 0.82% of electricity production. However, offshore wind still only counts for a very small amount and development has only taken place in North European counties round the North Sea and the Baltic Sea over the last 15 years. Offshore wind is still some 50% more expensive than onshore wind, but more wind resources and lesser visual impacts from larger turbines are expected to compensate for the higher installation costs in the long term. Most offshore wind farms are installed in British, Swedish and Danish waters, and present-day costs of installing wind energy in the UK are between 1,200 to 1,600 GBP/kW (1,781 to 2,375 Euro/kW) offshore, while in Sweden investment costs were 1,800 Euro/kW, and in Denmark 1,200 to 1,700 Euro/kW, though investment costs for a new wind farm are expected be in the range of 2.0 to 2.2 mill. Euro/MW for a near-shore shallow depth facility. Future developments in offshore wind technology concerning aerodynamics, structural dynamics, structural design, machine elements, electrical design and grid integration could drive investment costs from present-day range of 1.9 to 2.2 mill. Euro/MW down to 1.35 - 1.54 mill.Euro/MW in 2050, which accounts for a reduction of costs of approx. 35%. In order to sum up progress and identify future research needs, the International Energy Agency (IEA) Wind agreement Task 11 should arrange a new meeting concerning long term research needs for reviewing 'the long term strategy for 2000 to 2020' from 2001, to come up with suggestions / recommendations on how to define and proceed with, the necessary research activities of the IEA Wind Agreement and governments involved on key wind issues related to offshore technologies. (au)

Evaluation of stress resultant of offshore jacket platform using neural network

Digital Repository Service at National Institute of Oceanography (India)

Mandal, S.; Hegde, G.; Gupta, K.G.

The safety of an offshore platform depends on the predicting environmental phenomena such as wind, current, wave, seismic loadings and accurate calculation of responses of the structure to these loads and determining the strength of the structure...

Offshore Wind Energy Resource Assessment for Alaska

Energy Technology Data Exchange (ETDEWEB)

Doubrawa Moreira, Paula [National Renewable Energy Lab. (NREL), Golden, CO (United States); Scott, George N. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Musial, Walter D. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Kilcher, Levi F. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Draxl, Caroline [National Renewable Energy Lab. (NREL), Golden, CO (United States); Lantz, Eric J. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2018-01-02

This report quantifies Alaska's offshore wind resource capacity while focusing on its unique nature. It is a supplement to the existing U.S. Offshore Wind Resource Assessment, which evaluated the offshore wind resource for all other U.S. states. Together, these reports provide the foundation for the nation's offshore wind value proposition. Both studies were developed by the National Renewable Energy Laboratory. The analysis presented herein represents the first quantitative evidence of the offshore wind energy potential of Alaska. The technical offshore wind resource area in Alaska is larger than the technical offshore resource area of all other coastal U.S. states combined. Despite the abundant wind resource available, significant challenges inhibit large-scale offshore wind deployment in Alaska, such as the remoteness of the resource, its distance from load centers, and the wealth of land available for onshore wind development. Throughout this report, the energy landscape of Alaska is reviewed and a resource assessment analysis is performed in terms of gross and technical offshore capacity and energy potential.

Corrosion protection of Arctic offshore structures: Final report. [Effects of temperature and salinity on required cathodic protection current

Energy Technology Data Exchange (ETDEWEB)

Sackinger, W.M.; Rogers, J.C.; Feyk, C.; Theuveny, B.

1985-10-01

Results are presented for a research program on corrosion prevention for Arctic offshore structures which are in contact with sea ice for a significant portion of the year. The electrical method most adaptable for structure protection involves the injection of impressed current from several remote anodes buried just beneath the sea floor. The electrical resistivity of annual sea ice as a function of temperature and salinity is presented. Details of the interface layers formed between sea ice and steel in the presence of current injection are shown. A computer program was developed to enable the calculation of protective current density into the structure, in the presence of ice rubble and ridges around the structure. The program and the results of an example calculation are given for a caisson- retained island structure. 81 refs., 103 figs., 3 tabs.

Decommissioning of offshore oil and gas installations

International Nuclear Information System (INIS)

Day, M.D.; Marks, M.H.

1997-01-01

A task facing the offshore oil and gas industry is the removal of about 7000 platforms. In this chapter, the legal framework for offshore platform decommissioning is first discussed. The various phases of abandonment are then described. The first and most critical of these is the planning phase which should be initiated years in advance when depletion plans for a field are recommended. Seven discrete activities are identified in the abandonment process itself and briefly discussed. These are: the permanent plugging and abandonment of non-productive well bores; pre-abandonment surveys and data gathering to gain knowledge about the platform and its condition; decommissioning; structure removal; disposal, recycle or reuse of platform components on or off shore; site clearance. (13 figures; 13 references) (UK)

Proceedings of the ENDOW workshop 'Offshore wakes: Measurements and modelling[Efficient Development of Offshore Windfarms

Energy Technology Data Exchange (ETDEWEB)

Barthelmie, R.J. (ed.)

2002-03-01

The papers presented in these Proceedings are the result of a workshop held at Risoe National Laboratory on March 7 and 8 2002 entitled 'Offshore Wakes: Measurements and Modelling'. The Workshop was arranged to showcase results of the European Community supported project 'Efficient Development of Offshore Windfarms (ENDOW)' and featured a series of eight presentations discussing modelling of wakes and boundary layers, existing and new measurements from offshore wind farms and how these will be linked in a new design tool and applied at planned offshore wind farms. In addition seven invited presentations covered a range of relevant topics from analytical approaches to fatigue and extreme loads in wind turbine clusters, current wake modelling in WAsP, optimising power production at Arklow Bank, Particle Image Velocimetry study of a wind turbine wake in a yaw, offshore wind measurements in Massachusetts, accuracy of SODAR measurements for wind energy and tidal influence of offshore wind speeds and turbulence. (au)

Organizational Adaptation in Offshoring

DEFF Research Database (Denmark)

Geisler Asmussen, Christian; Møller Larsen, Marcus; Pedersen, Torben

2016-01-01

Offshoring offers managers the promise of substantial economic benefits, but also comes with the risk of increased complexity and coordination challenges. We argue that offshoring firms must accumulate architectural knowledge to keep the cost of coordination of the geographically separated activi...

Offshore wind development research.

Science.gov (United States)

2014-04-01

Offshore wind (OSW) development is a new undertaking in the US. This project is a response to : New Jerseys 2011 Energy Master Plan that envisions procuring 22.5% of the states power : originating from renewable sources by 2021. The Offshore Wi...

Offshore Fish Community: Ecological Interactions | Science ...

Science.gov (United States)

The offshore (>80 m) fish community of Lake Superior is made up of predominately native species. The most prominent species are deepwater sculpin, kiyi, cisco, siscowet lake trout, burbot, and the exotic sea lamprey. Bloater and shortjaw cisco are also found in the offshore zone. Bloater is abundant in the offshore zone but appears restricted to depths shallower than 150 m (Selgeby and Hoff 1996; Stockwell et al. 2010), although it occuppied greater depths several decades ago (Dryer 1966; Peck 1977). Shortjaw is relatively rare in the offshore zone (Hoff and Todd 2004; Gorman and Hoff 2009; Gorman and Todd 2007). Lake whitefish is also known to frequent bathymetric depths >100 m (Yule et al. 2008b). In this chapter, we develop a conceptual model of the offshore food web based on data collected during 2001-2005 and on inferences from species interactions known for the nearshore fish community. We then develop a framework for examination of energy and nutrient movements within the pelagic and benthic habitats of the offshore zone and across the offshore and nearshore zones. To document research results.

Offshore Wind Power Planning in Korea

DEFF Research Database (Denmark)

Seo, Chul Soo; Cha, Seung-Tae; Park, Sang Ho

2012-01-01

this possible, Korea has announced the National offshore power roadmap and is now in pursuit. However, large scale offshore wind farms can incur many problems, such as power quality problems, when connecting to a power system.[1][2] Thus, KEPCO is on the process of a research study to evaluate the effects...... that connecting offshore wind power generation to a power system has on the power system. This paper looks over offshore wind power planning in Korea and describes the development of impact assessment technology of offshore wind farms.......Wind power generation is globally recognized as the most universal and reliable form of renewable energy. Korea is currently depending mostly on coal and petroleum to generate electrical power and is now trying to replace them with renewable energy such as offshore wind power generation. To make...

Offshore system for integration of the wind energy; Sistema offshore para integracao de energia eolica

Energy Technology Data Exchange (ETDEWEB)

Decker, Jan de [3E, Brussels (Belgium); Tambke, Jens [Universidade de Oldemburg (Germany). ForWind; Voelker, J. [Dena - Agencia Alema de Energia (Germany); Michalowska-Knap, Katarzyna [Instituto de Energia Renovavel (Poland)

2010-09-15

The Offshore Grid project aims to analyze the conditions required for the development of an offshore transmission network to integrate renewable energy (wind) to the national electrical systems, securely and efficiently. Regulatory aspects, technical, economic and political are considered, that will help the various players in the industry to have a common view on the offshore power grids in Europe.

Application of slender wing benefits to military aircraft

Science.gov (United States)

Polhamus, E. C.

1983-01-01

A review is provided of aerodynamic research conducted at the Langley Research Center with respect to the application of slender wing benefits in the design of high-speed military aircraft, taking into account the supersonic performance and leading-edge vortex flow associated with very highly sweptback wings. The beginning of the development of modern classical swept wing jet aircraft is related to the German Me 262 project during World War II. In the U.S., a theoretical study conducted by Jones (1945) pointed out the advantages of the sweptback wing concept. Developments with respect to variable sweep wings are discussed, taking into account early research in 1946, a joint program of the U.S. with the United Kingdom, the tactical aircraft concept, and the important part which the Langley variable-sweep research program played in the development of the F-111, F-14, and B-1. Attention is also given to hybrid wings, vortex flow theory development, and examples of flow design technology.

Sinking offshore platform. Nedsenkbar fralandsplatform

Energy Technology Data Exchange (ETDEWEB)

Einstabland, T.B.; Olsen, O.

1988-12-19

The invention deals with a sinking offshore platform of the gravitational type designed for being installed on the sea bed on great depths. The platform consists of at least three inclining pillars placed on a foundation unit. The pillars are at the upper end connected to a tower structure by means of a rigid construction. The tower supports the platform deck. The rigid construction comprises a centre-positioned cylinder connected to the foundation. 11 figs.

A New Coordinated Voltage Control Scheme for Offshore AC Grid of HVDC Connected Offshore Wind Power Plants

DEFF Research Database (Denmark)

Sakamuri, Jayachandra N.; Cutululis, Nicolaos Antonio; Rather, Zakir Hussain

2015-01-01

This paper proposes a coordinated voltage control scheme (CVCS) which enhances the voltage ride through (VRT) capability of an offshore AC grid comprised of a cluster of offshore wind power plants (WPP) connected through AC cables to the offshore voltage source converter based high voltage DC (VSC......-HVDC) converter station. Due to limited short circuit power contribution from power electronic interfaced variable speed wind generators and with the onshore main grid decoupled by the HVDC link, the offshore AC grid becomes more vulnerable to dynamic voltage events. Therefore, a short circuit fault...... in the offshore AC Grid is likely to have significant implications on the voltage of the offshore AC grid, hence on the power flow to the onshore mainland grid. The proposed CVCS integrates individual local reactive power control of wind turbines and of the HVDC converter with the secondary voltage controller...

Offshore Wind Market and Economic Analysis

Energy Technology Data Exchange (ETDEWEB)

Hamilton, Bruce Duncan [Navigant Consulting, Inc., Chicago, IL (United States)

2014-08-27

This report is the third annual assessment of the U.S. offshore wind market. It includes the following major sections: Section 1: key data on developments in the offshore wind technology sector and the global development of offshore wind projects, with a particular focus on progress in the United States; Section 2: analysis of policy developments at the federal and state levels that have been effective in advancing offshore wind deployment in the United States; Section 3: analysis of actual and projected economic impact, including regional development and job creation; Section 4: analysis of developments in relevant sectors of the economy with the potential to affect offshore wind deployment in the United States

Import, Offshoring and Wages

DEFF Research Database (Denmark)

Fosse, Henrik Barslund; Maitra, Madhura

Offshoring firms are found to pay higher average wages than purely domestic firms. We provide a unifying empirical approach by capturing the different channels through which offshoring may explain this wage difference: (i) due to change in the composition of workers (skill composition effect) (ii......) because all existing workers get higher pay (rent sharing effect). Using Danish worker-firm data we explain how much each channel contributes to higher wages. To estimate the causal effect of offshoring on wages we use China’s accession to the WTO in December 2001 - and the soon after boom in Chinese...

Potential role of power authorities in offshore wind power development in the US

International Nuclear Information System (INIS)

Dhanju, Amardeep; Firestone, Jeremy; Kempton, Willett

2011-01-01

This article examines how power authorities could facilitate and manage offshore wind power development in US coastal waters. The power authority structure is an American 20th century institution for managing energy resources-a form of a public authority or public corporation dedicated to creating, operating and maintaining electric generation and transmission infrastructure. Offshore wind power is characterized by high capital costs but no fuel costs and thus low operating costs. Therefore a power authority, by virtue of its access to low-cost capital and managerial flexibility, could facilitate offshore wind power development by reducing financial risk of developing and lowering debt payments, thus improving the risk profile and lowering the cost of electricity production. Additionally, power authorities can be made up of multiple states, thus opening the possibility for joint action by neighboring coastal states. Using primary and secondary data, we undertake an in-depth analysis of the potential benefits and shortcomings of a power authority approach. - Highlights: → Proposes an institutional solution in the form of power authority for offshore wind power. → Power authority structure can significantly lower the cost of capital. → Tax-free bond financing available to power authority can significantly reduce the cost of energy. → It can enhance regional collaboration among coastal states to harness the offshore wind potential.

Convection From a Slender Cylender in a Ventilated Room

DEFF Research Database (Denmark)

Heiselberg, Per Kvols; Sandberg, M.

1990-01-01

with measurements in the boundary layer flow around a heated vertical slender cylinder in a full-scale test room with displacement ventilation. Both velocity and temperature profiles in the boundary layer flow were recorded. The room was ventilated by a low velocity diffuser, standing on the floor, from which air......The equations, based on an integral formulation, for turbulent natural boundary layer flow are solved in both the constant temperature case and in the constant heat flux case. Solutions are found. for convection along both flat plates and cylinders. Theoretical predictions are compared...... with a negative buoyancy was supplied. The vertical distribution of both temperature and contamination in the room was measured as a function of the heat load and the air flow rate. The contaminant distribution showed a clear stratification between clean and contaminated air, while the temperature was increasing...

Computation of compressible quasi-axisymmetric slender vortex flow and breakdown

Science.gov (United States)

Kandil, Osama A.; Kandil, Hamdy A.

1991-01-01

The unsteady, compressible Navier-Stokes equations are used to compute and analyze compressible quasi-axisymmetric isolated vortices. The Navier-Stokes equations are solved using an implicit, upwind, flux difference splitting finite volume scheme. The developed three dimensional solver was verified by comparing its solution profiles with those of a slender, quasi-axisymmetric vortex solver for a subsonic, quasi-axisymmetric vortex in an unbounded domain. The Navier-Stokes solver is then used to solve for a supersonic, quasi-axisymmetric vortex flow in a configured circular duct. Steady and unsteady vortex-shock interactions and breakdown were captured. The problem was also calculated using the Euler solver of the same code; the results were compared with those of the Navier-Stokes solver. The effect of the initial swirl was investigated.

Electrical Structure of Future Off-shore Wind Power Plant with a High Voltage Direct Current Power Transmission

DEFF Research Database (Denmark)

Sharma, Ranjan

The increasing demand of electric power and the growing consciousness towards the changing climate has led to a rapid development of renewable energy in the recent years. Among all, wind energy has been the fastest growing energy source in the last decade. But the growing size of wind power plants......, better wind conditions at off-shore and the general demand to put them out of sight have all contributed to the installation of large wind power plants in off-shore condition. However, moving wind power plants far out in the off-shore comes with many associated problems. One of the main challenges...... is the transmission of power over long distance. Historically, the power transmission from off-shore wind power plants has been done via HVAC submarine cables. This provides a simple solution, but AC cables cannot be arbitrarily long. It is shown in the report that major issues with HVAC cable transmission system...

The economics of offshore wind

International Nuclear Information System (INIS)

Green, Richard; Vasilakos, Nicholas

2011-01-01

This paper presents an overview of the main issues associated with the economics of offshore wind. Investment in offshore wind systems has been growing rapidly throughout Europe, and the technology will be essential in meeting EU targets for renewable energy in 2020. Offshore wind suffers from high installation and connection costs, however, making government support essential. We review various support policies used in Europe, concluding that tender-based feed-in tariff schemes, as used in Denmark, may be best for providing adequate support while minimising developers' rents. It may prove economic to build an international offshore grid connecting wind farms belonging to different countries that are sited close to each other. (author)

The economics of offshore wind

Energy Technology Data Exchange (ETDEWEB)

Green, Richard; Vasilakos, Nicholas [Department of Economics, University of Birmingham, Birmingham B15 2TT (United Kingdom)

2011-02-15

This paper presents an overview of the main issues associated with the economics of offshore wind. Investment in offshore wind systems has been growing rapidly throughout Europe, and the technology will be essential in meeting EU targets for renewable energy in 2020. Offshore wind suffers from high installation and connection costs, however, making government support essential. We review various support policies used in Europe, concluding that tender-based feed-in tariff schemes, as used in Denmark, may be best for providing adequate support while minimising developers' rents. It may prove economic to build an international offshore grid connecting wind farms belonging to different countries that are sited close to each other. (author)

NREL Offshore Balance-of-System Model

Energy Technology Data Exchange (ETDEWEB)

Maness, Michael [National Renewable Energy Lab. (NREL), Golden, CO (United States); Maples, Benjamin [National Renewable Energy Lab. (NREL), Golden, CO (United States); Smith, Aaron [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2017-01-01

The U.S. Department of Energy (DOE) has investigated the potential for 20% of nationwide electricity demand to be generated from wind by 2030 and, more recently, 35% by 2050. Achieving this level of wind power generation may require the development and deployment of offshore wind technologies. DOE (2008) has indicated that reaching these 2030 and 2050 scenarios could result in approximately 10% and 20%, respectively, of wind energy generation to come from offshore resources. By the end of 2013, 6.5 gigawatts of offshore wind were installed globally. The first U.S. project, the Block Island Wind Farm off the coast of Rhode Island, has recently begun operations. One of the major reasons that offshore wind development in the United States is lagging behind global trends is the high capital expenditures required. An understanding of the costs and associated drivers of building a commercial-scale offshore wind plant in the United States will inform future research and help U.S. investors feel more confident in offshore wind development. In an effort to explain these costs, the National Renewable Energy Laboratory has developed the Offshore Balance-of-System model.

MARE-WINT. New Materials and Reliability in Offshore Wind Turbine Technology

DEFF Research Database (Denmark)

This book provides a holistic, interdisciplinary overview of offshore wind energy, and is a must-read for advanced researchers. Topics, from the design and analysis of future turbines, to the decommissioning of wind farms, are covered. The scope of the work ranges from analytical, numerical...... and experimental advancements in structural and fluid mechanics, to novel developments in risk, safety & reliability engineering for offshore wind. The core objective of the current work is to make offshore wind energy more competitive, by improving the reliability, and operations and maintenance (O&M) strategies...... of wind turbines. The research was carried out under the auspices of the EU-funded project, MARE-WINT. The work seeks to bridge the gap between research and a rapidly-evolving industry....

Offshore wind energy. An overview on the activities in Germany; Offshore-Windenergie. Ein Ueberblick ueber die Aktivitaeten in Deutschland

Energy Technology Data Exchange (ETDEWEB)

Worm, Anja [media consulta Deutschland GmbH, Berlin (Germany)

2013-02-15

The brochure under consideration provides an overview of the activities of offshore wind energy in Germany. The first offshore wind farms are built and generate more electricity than expected. The offshore wind farms serve as a field of learning for new technologies. The power of offshore wind farms opened new prospects for the economy. The northern Federal States of Germany as well as the traditional locations for mechanical engineering and steel production benefit from offshore wind energy.

Danish offshore wind - Key environmental issues

International Nuclear Information System (INIS)

2006-11-01

Danish experience from the past 15 years shows that offshore wind farms, if placed right, can be engineered and operated without significant damage to the marine environment and vulnerable species. The comprehensive environmental monitoring programmes of Horns Rev Offshore Wind Farm and Nysted Offshore Wind Farm confirm that, under the rieght conditions, even big wind farms pose low risk to birds, mammals and fish, even though there will be changes in the living conditions of some species by an increase in habitat heterogeneity. The monitoring also shows that appropriate siting of offshore wind farms is an essential precondition for ensuring limited impact on nature and the environment, and that careful spatial planning is necessary to avoid damaging cumulative impacts. Due consideration to limiting the impacts on nature together with positive attitudes towards offshore wind farms in local communities and challenging energy policy objectives at national and international levels mean that prospects look bright for future offshore expansion. (au)

A stakeholder analysis of divergent supply-chain trends for the European onshore and offshore wind installations

International Nuclear Information System (INIS)

Wüstemeyer, Christoph; Madlener, Reinhard; Bunn, Derek W.

2015-01-01

This paper provides a survey-based analysis of investment decisions and structural shifts related to onshore and offshore wind power supply chains. Insights on cost reductions are obtained from a detailed stakeholder survey conducted amongst the European wind power industry in 2012. Overall, a rather more optimistic view of the scope for cost reductions in offshore technology is presented than has previously been evident in empirical analysis. From the analysis we conclude that the wind power industry has experienced a decoupling process of the offshore supply chain from its onshore counterpart with diverging technological requirements. For policy-makers, it is essential to acknowledge that barriers to adoption and the consequent needs for subsidies among the players in the onshore and offshore supply chains seem to differ, and that a micro-level analysis of the innovations and risks involved at the various stages in the supply chain is necessary. - Highlights: • Survey-based analysis of supply chain trends in the European wind energy industry. • Study of technology adoption decisions, structural shifts, and cost projections. • Results reveal a decoupling process between onshore and offshore supply chains. • Possibilities to transfer knowledge from the onshore to the offshore product vary. • The divergent barriers to adoption need to be accounted for by policy-makers

Offshore Outsourcing

DEFF Research Database (Denmark)

Petersen, Bent; Benito, Gabriel R. G.; Dovgan, Olesya

While the extant literature on offshore outsourcing deals with this operation mode in isolation, and typically with a focus on cost effects, we address the broader question of how companies choose and use outsourcing as part of foreign operation mode development and as a contributor to internatio...... that outsourcing can be used proactively to promote expanded international operations.......While the extant literature on offshore outsourcing deals with this operation mode in isolation, and typically with a focus on cost effects, we address the broader question of how companies choose and use outsourcing as part of foreign operation mode development and as a contributor...

Estimation of the vibration decrement of an offshore wind turbine support structure caused by its interaction with soil

Energy Technology Data Exchange (ETDEWEB)

Versteijlen, W.G; Metrikine, A.; Hoving, J.S.; Smidt, E.H.; De Vries, W.E. [Department Hydraulic Engineering, Faculty of Civil Engineering and Geosciences, Delft University of Technology TUD, Delft (Netherlands)

2012-01-15

In today's cutting costs environment in the offshore wind industry, significant achievements can be made with a better assessment of dynamic soil-pile interaction. Of the main damping mechanisms active at an OWT (offshore wind turbine), least is known about soil damping. The values for this contribution used in the industry today - mostly calculated analogously to a study performed in 1980 - are expected to be on the low side. More research on the topic is recommended. Presence of more damping than currently assumed, would signify that the (often) design driving fatigue damage accumulation is lower than assumed. This would justify designing more light-weight structures using less construction steel, or allowing for longer (insured) OWT lifetimes then the now applied 20 years. Both these measures significantly decrease costs of offshore wind. This paper evaluates measured signals of twelve 'rotorstop' - test on an OWT at Dong Energy owned - Burbo Banks windfarm. The vibration decay was measured with an accelerometer and strain gauges along the tower. A simplistic analytical model has been developed enabling analyses of the measured signals. Two main modal shapes were identified with similar shape, but deviating amplitudes in the soil profile. The large difference in damping that exists between the vibrations of these modes is attributed to the difference in influence that the soil can have on these vibrations. The found effect of soil on the damping of this particular OWT is significantly larger than the order of magnitude used in the industry today.

Small-Scale Quasi-Static Tests on Non-Slender Piles Situated in Sand

DEFF Research Database (Denmark)

Sørensen, Søren Peder Hyldal; Ibsen, Lars Bo

In the period from February 2009 till March 2011 a series of small-scale tests on pile foundations has been conducted at Aalborg University. In all the tests the piles have been exposed to quasi-static loading and all the tests have been conducted in a pressure tank. The objective of the tests has...... been to investigate the effect of pile diameter and length to diameter ratio on the soil response in sand for non-slender piles. Further, the tests have been conducted to calibrate a three-dimensional numerical model in the commercial program FLAC3D....

Body Image of Dancers in Los Angeles: The Cult of Slenderness and Media Influence among Dance Students

Science.gov (United States)

Heiland, Teresa L.; Murray, Darrin S.; Edley, Paige P.

2008-01-01

Body image and self-esteem are examined through personal stories among Los Angeles college dancers who grew up in the Hollywood culture of the cult of slenderness. The study incorporates a body image survey, eating disorder screen, and an interview process capturing dancers' lived experiences with daily pressures. Dancers reveal their experiences…

2016 Offshore Wind Market Report

Energy Technology Data Exchange (ETDEWEB)

Musial, Walter [National Renewable Energy Lab. (NREL), Golden, CO (United States); Beiter, Philipp [National Renewable Energy Lab. (NREL), Golden, CO (United States); Schwabe, Paul [National Renewable Energy Lab. (NREL), Golden, CO (United States); Tian, Tian [National Renewable Energy Lab. (NREL), Golden, CO (United States); Stehly, Tyler [National Renewable Energy Lab. (NREL), Golden, CO (United States); Spitsen, Paul [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2017-08-07

The 2016 Offshore Wind Technologies Market Report is intended to provide stakeholders with quantitative information about the offshore wind market, technology, and cost trends in the United States and worldwide.

"It's still a great adventure" - exploring offshore employees' working conditions in a qualitative study.

Science.gov (United States)

Mette, Janika; Velasco Garrido, Marcial; Harth, Volker; Preisser, Alexandra M; Mache, Stefanie

2017-01-01

Despite the particular demands inherent to offshore work, little is known about the working conditions of employees in the German offshore wind industry. To date, neither offshore employees' job demands and resources, nor their needs for improving the working conditions have been explored. Therefore, the aim of this study was to conduct a qualitative analysis to gain further insight into these topics. Forty-two semi-structured telephone interviews with German offshore employees ( n  = 21) and offshore experts ( n  = 21) were conducted. Employees and experts were interviewed with regard to their perceptions of their working conditions offshore. In addition, employees were asked to identify areas with potential need for improvement. The interviews were analysed in a deductive-inductive process according to Mayring's qualitative content analysis. Employees and experts reported various demands of offshore work, including challenging physical labour, long shifts, inactive waiting times, and recurrent absences from home. In contrast, the high personal meaning of the work, regular work schedule (14 days offshore, 14 days onshore), and strong comradeship were highlighted as job resources. Interviewees' working conditions varied considerably, e.g. regarding their work tasks and accommodations. Most of the job demands were perceived in terms of the work organization and living conditions offshore. Likewise, employees expressed the majority of needs for improvement in these areas. Our study offers important insight into the working conditions of employees in the German offshore wind industry. The results can provide a basis for further quantitative research in order to generalize the findings. Moreover, they can be utilized to develop needs-based interventions to improve the working conditions offshore.

Wave loads on offshore wind turbines: Accurate tools and structural response

DEFF Research Database (Denmark)

Bredmose, Henrik

2014-01-01

Can the design models for offshore wind turbine wave loads be improved? And how will that change the overall load picture? Core questions of the Wave Loads project which was finalised in 2013 with two PhD theses, response calculations for jackets and monopiles, a detailed set of experiments and a3D...... coupled CFD wave solver...

CFD for wind and tidal offshore turbines

CERN Document Server

Montlaur, Adeline

2015-01-01

The book encompasses novel CFD techniques to compute offshore wind and tidal applications. Computational fluid dynamics (CFD) techniques are regarded as the main design tool to explore the new engineering challenges presented by offshore wind and tidal turbines for energy generation. The difficulty and costs of undertaking experimental tests in offshore environments have increased the interest in the field of CFD which is used to design appropriate turbines and blades, understand fluid flow physical phenomena associated with offshore environments, predict power production or characterise offshore environments, amongst other topics.

Energy from Offshore Wind: Preprint

Energy Technology Data Exchange (ETDEWEB)

Musial, W.; Butterfield, S.; Ram, B.

2006-02-01

This paper provides an overview of the nascent offshore wind energy industry including a status of the commercial offshore industry and the technologies that will be needed for full market development.

Development of High Heat Input Welding Offshore Steel as Normalized Condition

Science.gov (United States)

Deng, Wei; Qin, Xiaomei

The heavy plate used for offshore structure is one of the important strategic products. In recent years, there is an increasing demand for heavy shipbuilding steel plate with excellent weldability in high heat input welding. During the thermal cycle, the microstructure of the heat affected zone (HAZ) of plates was damaged, and this markedly reduced toughness of HAZ. So, how to improve the toughness of HAZ has been a key subject in the fields of steel research. Oxide metallurgy is considered as an effective way to improve toughness of HAZ, because it could be used to retard grain growth by fine particles, which are stable at the high temperature.The high strength steel plate, which satisfies the low temperature specification, has been applied to offshore structure. Excellent properties of the plates and welded joints were obtained by oxide metallurgy technology, latest controlled rolling and accelerated cooling technology using Ultra-Fast Cooling (an on-line accelerated cooling system). The 355MPa-grade high strength steel plates with normalizing condition were obtained, and the steels have excellent weldability with heat input energy of 79 287kJ/cm, and the nil ductility transition (NDT) temperature was -70°C, which can satisfy the construction of offshore structure in cold regions.

Utilizing offshore potentials for wind power generation; Nutzung der Offshore-Potentiale fuer die Windenergie

Energy Technology Data Exchange (ETDEWEB)

Hannemann, H. [Neptun Industrie GmbH, Rostock (Germany)

2000-07-01

The contribution discusses the importance of the offshore market and recommends measures to develop it. A turnkey offer is required for exports, which means that all organisations cooperating in the pilot project must prove their competence. The status of a pilot project in the Baltic Sea and the further plans for the park (20 systems, 40 MW, more than 10 km off the coast, water depth about 20 m) are reviewed. [German] Zur Erschliessung des Offshore - Marktes fuer Windenergieanlagen ist es erforderlich, die Technologie ''vor der eigenen Haustuer'' demonstrieren zu koennen. Nach einer Betrachtung der europaeischen Offshore - Windenergie - Potentiale und der davon moeglicherweise nutzbaren Anteile wird die Bedeutung des Offshore - Marktes deutlich. Besonders fuer die Hersteller ist der Offshore - Markt fuer den langfristigen Export von besonderer Bedeutung. Um den Export zu realisieren, ist ein Turnkey - Angebot erforderlich, so dass im Pilotprojekt alle an der gesamten Realisation beteiligten Organisationen ihre Kompetenz beweisen muessen und koennen. Der Stand eines Pilotprojektes in der Ostsee und die weitere Planung fuer den Park (20 Anlagen, 40 MW, >10 km Kuestenentfernung, ca. 20 m Wassertiefe) wird dargestellt. (orig.)

Seismogenic structures of the 2006 ML4.0 Dangan Island earthquake offshore Hong Kong

Science.gov (United States)

Xia, Shaohong; Cao, Jinghe; Sun, Jinlong; Lv, Jinshui; Xu, Huilong; Zhang, Xiang; Wan, Kuiyuan; Fan, Chaoyan; Zhou, Pengxiang

2018-02-01

The northern margin of the South China Sea, as a typical extensional continental margin, has relatively strong intraplate seismicity. Compared with the active zones of Nanao Island, Yangjiang, and Heyuan, seismicity in the Pearl River Estuary is relatively low. However, a ML4.0 earthquake in 2006 occurred near Dangan Island (DI) offshore Hong Kong, and this site was adjacent to the source of the historical M5.8 earthquake in 1874. To reveal the seismogenic mechanism of intraplate earthquakes in DI, we systematically analyzed the structural characteristics in the source area of the 2006 DI earthquake using integrated 24-channel seismic profiles, onshore-offshore wide-angle seismic tomography, and natural earthquake parameters. We ascertained the locations of NW- and NE-trending faults in the DI sea and found that the NE-trending DI fault mainly dipped southeast at a high angle and cut through the crust with an obvious low-velocity anomaly. The NW-trending fault dipped southwest with a similar high angle. The 2006 DI earthquake was adjacent to the intersection of the NE- and NW-trending faults, which suggested that the intersection of the two faults with different strikes could provide a favorable condition for the generation and triggering of intraplate earthquakes. Crustal velocity model showed that the high-velocity anomaly was imaged in the west of DI, but a distinct entity with low-velocity anomaly in the upper crust and high-velocity anomaly in the lower crust was found in the south of DI. Both the 1874 and 2006 DI earthquakes occurred along the edge of the distinct entity. Two vertical cross-sections nearly perpendicular to the strikes of the intersecting faults revealed good spatial correlations between the 2006 DI earthquake and the low to high speed transition in the distinct entity. This result indicated that the transitional zone might be a weakly structural body that can store strain energy and release it as a brittle failure, resulting in an earthquake

Wind energy in offshore grids

Energy Technology Data Exchange (ETDEWEB)

Schroeder, S.T.

2013-01-15

This cumulative PhD thesis deals with wind integration in offshore grids from an economic point of view. It is composed of a generic part and eight papers. As the topic has mostly been analysed with a focus on topology and technical issues until now, market-operational questions in offshore grids and investment implications under different regulatory frameworks are a hitherto underrepresented research field. They are addressed by this thesis. Offshore grids between several countries combine the absorption of wind energy with international power trading. However, the inclusion into an offshore grid affects the economics of an offshore wind park. It is shown that the spot market income is lower if an offshore wind farm is placed in an interconnector and subject to nodal pricing instead of having a national affiliation. Moreover, congestion in the interconnector can prevent the wind farm from correcting its wind forecast errors in a specific onshore balancing group. An analytical approach with a transmission system operator and a wind farm as stakeholders illustrates resulting incentives for strategic behaviour. Depending on the regulatory regime, they may be inclined to announce more or less generation than expected at the closure of the day-ahead spot market. This can lead to a suboptimal utilisation of the infrastructure and associated socio-economic losses. These and possibly undesired reallocative effects between the parties can be avoided if the regulatory regime is adjusted to reflect special characteristics of offshore grids. With an operational real options approach, it is furthermore illustrated how different support schemes and connections to additional countries affect the investment case of an offshore wind farm and the income of the transmission system operator. The investment framework has also been addressed with a policy study about possible combinations of support schemes and international cooperation mechanisms between countries to achieve their

Cryptic diversity and population genetic structure in the rare, endemic, forest-obligate, slender geckos of the Philippines.

Science.gov (United States)

Siler, Cameron D; Dececchi, T Alex; Merkord, Chris L; Davis, Drew R; Christiani, Tony J; Brown, Rafe M

2014-01-01

Recent studies of forest lizards in Southeast Asia have highlighted spectacular morphological and cryptic genetic diversity in several poorly known clades. Unfortunately, many of the included species have microhabitat preferences for forested environments, and therefore they are threatened by extensive forest destruction throughout the region. This is particularly true in the Philippines, an archipelago with a strikingly high proportion (84%) of endemic geckos. Abundances inferred from historical museum collections suggests that we are in a critical period where apparent declines in population viability and species' abundance have taken place faster than the growth in our understanding of alpha diversity. This phenomenon is exemplified in the exceedingly rare Philippine slender forest geckos of the genus Pseudogekko. Most of the known species are rarely encountered by field biologists, and species boundaries are unclear; this poor state of knowledge impedes effective conservation measures. Using the first multilocus phylogeny for these taxa, and phylogenetic and population genetic approaches, we elucidate evolutionary lineages and delimit species-level conservation targets in this unique radiation of endemic Philippine geckos. The results support the presence of widespread cryptic diversity in the genus, providing a framework for the re-evaluation of conservation priorities aimed at protecting these rare, forest-obligate species. Copyright © 2013 Elsevier Inc. All rights reserved.

Large Eddy Simulation of Flows Associated with Offshore Oil and Gas Pipeline

Directory of Open Access Journals (Sweden)

Nizamani Z.

2017-01-01

Full Text Available Fluid structure interaction (FSI applications are of wide range from offshore fixed and floating structures to offshore pipelines. Reynolds Averaged Navier Stoke (RANS solution has limitation for unsteady and turbulent flow modelling. A possible approach is Large Eddy Simulation (LES and it is applied to flows past a circular cylinder located far above, near and on a flat seabed. The Reynolds number considered is based on the real situation off Malaysia Coast and is sub-critical around 105. Hydrodynamic quantities in terms of mean pressure are predicted and vortex shedding mechanism is evaluated. The results are validated by comparing the simulation and experimental previous studies.

Floating Offshore Wind in Hawaii: Potential for Jobs and Economic Impacts from Three Future Scenarios

Energy Technology Data Exchange (ETDEWEB)

Jimenez, Tony; Keyser, David; Tegen, Suzanne

2016-04-18

Construction of the first offshore wind power plant in the United States began in 2015, off the coast of Rhode Island, using fixed platform structures that are appropriate for shallow seafloors, like those located off the East Coast and mid-Atlantic. However, floating platforms, which have yet to be deployed commercially, will likely need to be anchored to the deeper seafloor if deployed in Hawaiian waters. To analyze the employment and economic potential for floating offshore wind off Hawaii's coasts, the Bureau of Ocean Energy Management commissioned the National Renewable Energy Laboratory (NREL) to analyze two hypothetical deployment scenarios for Hawaii: 400 MW of offshore wind by 2050 and 800 MW of offshore wind by 2050. The results of this analysis can be used to better understand the general scale of economic opportunities that could result from offshore wind development.

Application of two passive strategies on the load mitigation of large offshore wind turbines

Science.gov (United States)

Shirzadeh, Rasoul; Kühn, Martin

2016-09-01

This study presents the numerical results of two passive strategies to reduce the support structure loads of a large offshore wind turbine. In the first approach, an omnidirectional tuned mass damper is designed and implemented in the tower top to alleviate the structural vibrations. In the second approach, a viscous fluid damper model which is diagonally attached to the tower at two points is developed. Aeroelastic simulations are performed for the offshore 10MW INNWIND.EU reference wind turbine mounted on a jacket structure. Lifetime damage equivalent loads are evaluated at the tower base and compared with those for the reference wind turbine. The results show that the integrated design can extend the lifetime of the support structure.

The Economic Geography of Offshoring

DEFF Research Database (Denmark)

Ørberg Jensen, Peter D.; Pedersen, Torben

2011-01-01

when distinguishing between standardized and advanced activities. Asia attracts as many advanced activities as Western Europe while North America attracts more advanced activities even in manufacturing. Central and Eastern Europe attract offshoring in manufacturing and IT, but the activities...... that are offshored to these regions are typically not advanced. One important theoretical implication of this study is that a more detailed understanding of the nature of offshored activities is needed, since such attributes appear to be an important determinant of location choice....

Offshore atomic power plants

International Nuclear Information System (INIS)

Anon.

1975-01-01

Various merits of offshore atomic power plants are illustrated, and their systems are assessed. The planning of the offshore atomic power plants in USA is reviewed, and the construction costs of the offshore plant in Japan were estimated. Air pollution problem may be solved by the offshore atomic power plants remarkably. Deep water at low temperature may be advantageously used as cooling water for condensers. Marine resources may be bred by building artificial habitats and by providing spring-up equipments. In the case of floating plants, the plant design can be standardized so that the construction costs may be reduced. The offshore plants can be classified into three systems, namely artificial island system, floating system and sea bottom-based system. The island system may be realized with the present level of civil engineering, but requires the development of technology for the resistance of base against earthquake and its calculation means. The floating system may be constructed with conventional power plant engineering and shipbuilding engineering, but the aseismatic stability of breakwater may be a problem to be solved. Deep water floating system and deep water submerging system are conceivable, but its realization may be difficult. The sea bottom-based system with large caissons can be realized by the present civil engineering, but the construction of the caissons, stability against earthquake and resistance to waves may be problems to be solved. The technical prediction and assessment of new plant sites for nuclear power plants have been reported by Science and Technology Agency in 1974. The construction costs of an offshore plant has been estimated by the Ministry of International Trade and Industry to be yen71,026/kW as of 1985. (Iwakiri, K.)

Offshoring and Changes in Firms’ Domestic Employment

DEFF Research Database (Denmark)

Timmermans, Bram; Østergaard, Christian Richter

difference on a set of employment characteristics, i.e. employment growth, growth in high skilled employees, and growth in employees with a background in science and engineering, by using a partial propensity score matching approach. The findings of the analyses show that there are clear differences between......In this paper, we investigate, by merging the Danish linked employer-employee database with a Danish offshoring survey, the difference in employment between offshoring and non-offshoring firms that are active in manufacturing industries and business services in Denmark. We measure the mean...... Danish offshoring and non-offshoring firms in how the employee composition changes over time. The change in employment composition differ considerably between manufacturing industries and business services and on whether firms offshore administrative and technical business functions or other types...

Characteristics of flow past a slender, emergent cylinder in shallow open channels

Science.gov (United States)

Heidari, Mehdi; Balachandar, Ram; Roussinova, Vesselina; Barron, Ronald M.

2017-06-01

The complex wake created by an emergent cylinder with a large aspect ratio in a shallow open channel flow is studied experimentally using particle image velocimetry. The unique characteristics of the bed-mounted slender cylinder wake are analysed. Velocity fields, turbulence parameters, and wake development in shallow open channel flow are studied at two different Reynolds numbers and subcritical Froude numbers by carrying out measurements in different horizontal and vertical planes. In the mid-depth plane, velocity and turbulence statistics are independent of Reynolds number, while higher turbulence intensities and Reynolds shear stresses were observed in the near-bed plane for the low Reynolds number case. The narrower wake is observed in the near-bed plane due to the effect of the bed. Combined with stronger vertical velocity and turbulence intensities noted near the bed in the vertical midplane, this suggests increased activity of the vortex structures in the low Reynolds number case. Under shallow conditions, stronger disturbances of the free surface are observed for the case of high Reynolds and Froude numbers. The study also revisits the definition of the wake stability parameter and proposes a new definition which incorporates not only the bed friction but also the drag experienced by the cylinder.

NEW OFFSHORE LOCATIONS IN THE EUROPEAN UNION

Directory of Open Access Journals (Sweden)

RADULESCU IRINA GABRIELA

2014-05-01

Full Text Available The offshore activity provides benefits for the host market and has positive effects on services, and on producers that use intermediate services. FDI in services has an important impact on the offshore activity, especially through transfer of technology. Many transnational companies have recognized the advantages of offshoring and the fact that it becomes a key globalization force. Recently, the Central European countries have become popular destinations among offshoring

Modelling and Simulation of Wave Loads

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard; Thoft-Christensen, Palle

velocity can be approximated by a Gaussian Markov process. Known approximate results for the first-passage density or equivalently, the distribution of the extremes of wave loads are presented and compared with rather precise simulation results. It is demonstrated that the approximate results......A simple model of the wave load on slender members of offshore structures is described. The wave elevation of the sea state is modelled by a stationary Gaussian process. A new procedure to simulate realizations of the wave loads is developed. The simulation method assumes that the wave particle...

Noise from offshore wind turbines

Energy Technology Data Exchange (ETDEWEB)

Soendergaard, B.; Plovsing, B.

2005-07-01

Noise assessment of wind turbines through calculations is based on sound power levels measured according to e.g. IEC 61400-11. With larger wind turbines and distances some of the calculation models give erroneous results. Noise propagation over water is different from propagation over land. For that reason it is important be able to make valid noise assessments for offshore wind farms. A suggestion for an offshore measurement method is described and a survey of models for noise propagation offshore has been made. (au)

Contribution to a probabilistic safety analysis for the dismantling of slender reinforced-concrete structures; Ein Beitrag zur probabilistischen Sicherheitsanalyse von Abbruchvorgaengen turmartiger Bauwerke aus Stahlbeton

Energy Technology Data Exchange (ETDEWEB)

Lehnen, D J

1998-12-31

In the present work a concept of probabilistic safety-analysis for the dismantling of slender concrete-structures by tilting is developed. Based on requirements, that define a regular dismantling process, models describing characteristic limit-states of the building are derived. The connection of these limit-states allows rating the whole process. Uncertainties in the model-input are caught by using stochastic variables. Uncertainties in the model itself are caught by using inferior and superior modelling. With the help of two concluding examples it is shown, how the obtained probability of failure can be used to enhance objectiveness of safety-considerations. The numeric simulation is based on a Monte-Carlo method. (orig.) [Deutsch] In der vorliegenden Arbeit wird ein Konzept zur probabilistischen Sicherheitsanalyse des Fallrichtungsabbruchs turmartiger Bauwerke aus Stahlbeton entwickelt. Ausgehend von einem definierten Anforderungsprofil an den ordnungsgemaessen Ablauf eines Fallrichtungsabbruchs werden Modellvorstellungen herausgearbeitet, die einzelne Bauwerksgrenzzustaende abbilden, welche sich zur Beurteilung des Gesamtvorgangs eignen. Unsicherheiten in den Eingangsgroessen werden durch deren Auffassung als Wahrschlichkeitsdichten erfasst. Unsicherheiten in den Modellbildungen werden durch den jeweiligen Einsatz unterschaetzender und ueberschaetzender Betrachtungen, sogenannter Minoranten und Majoranten, beruecksichtigt. Anhand zweier Beispiele wird abschliessend demonstriert, wie die erhaltene operative Versagenswahrscheinlichkeit zur Objektivierung von Sicherheitsbetrachtungen herangezogen werden kann. Dabei beruht die numerische Umsetzung auf einer Monte-Carlo Simulation. (orig.)

Contribution to a probabilistic safety analysis for the dismantling of slender reinforced-concrete structures; Ein Beitrag zur probabilistischen Sicherheitsanalyse von Abbruchvorgaengen turmartiger Bauwerke aus Stahlbeton

Energy Technology Data Exchange (ETDEWEB)

Lehnen, D.J.

1997-12-31

In the present work a concept of probabilistic safety-analysis for the dismantling of slender concrete-structures by tilting is developed. Based on requirements, that define a regular dismantling process, models describing characteristic limit-states of the building are derived. The connection of these limit-states allows rating the whole process. Uncertainties in the model-input are caught by using stochastic variables. Uncertainties in the model itself are caught by using inferior and superior modelling. With the help of two concluding examples it is shown, how the obtained probability of failure can be used to enhance objectiveness of safety-considerations. The numeric simulation is based on a Monte-Carlo method. (orig.) [Deutsch] In der vorliegenden Arbeit wird ein Konzept zur probabilistischen Sicherheitsanalyse des Fallrichtungsabbruchs turmartiger Bauwerke aus Stahlbeton entwickelt. Ausgehend von einem definierten Anforderungsprofil an den ordnungsgemaessen Ablauf eines Fallrichtungsabbruchs werden Modellvorstellungen herausgearbeitet, die einzelne Bauwerksgrenzzustaende abbilden, welche sich zur Beurteilung des Gesamtvorgangs eignen. Unsicherheiten in den Eingangsgroessen werden durch deren Auffassung als Wahrschlichkeitsdichten erfasst. Unsicherheiten in den Modellbildungen werden durch den jeweiligen Einsatz unterschaetzender und ueberschaetzender Betrachtungen, sogenannter Minoranten und Majoranten, beruecksichtigt. Anhand zweier Beispiele wird abschliessend demonstriert, wie die erhaltene operative Versagenswahrscheinlichkeit zur Objektivierung von Sicherheitsbetrachtungen herangezogen werden kann. Dabei beruht die numerische Umsetzung auf einer Monte-Carlo Simulation. (orig.)

Some characteristics of offshore operations

Directory of Open Access Journals (Sweden)

Popov Đorđe

2011-01-01

Full Text Available Offshore operations are not on the margins of the world economy. They are an integral part of modern business practice. They have become one of the most important instruments in the contemporary globalized financial system. Offshore operations and tax havens are not only conduits for tax avoidance and evasion but belong more broadly to the world of finance, for the business of managing the monetary resources of an organization, country or individuals. Offshore business operating in tax havens is at the heart of a particular type of globalization that is characterized by a growing gap between the very rich and everyone else. Tax havens are financial conduits that, in exchange for a fee, use their one principal asset- their sovereignty to serve a nonresident constituency of accountants and lawyers, bankers and financiers, who bring a demand for offshore operations.

Learning Paths to Offshore Outsourcing

DEFF Research Database (Denmark)

Maskell, Peter; Pedersen, Torben; Petersen, Bent

A corporation’s offshore outsourcing may be seen as the result of a discrete, strategic decision taken in response to an increasing pressure from worldwide competition. However, empirical evidence of a representative cross-sector sample of international Danish firms indicates that offshore sourcing...... in low-cost countries is best described as a learning-by-doing process in which the offshore outsourcing of a corporation goes through a sequence of stages towards sourcing for innovation. Initially, a corporation’s outsourcing is driven by a desire for cost minimization. Over a period of time...... the outsourcing experience lessens the cognitive limitations of decision-makers as to the advantages that can be achieved through outsourcing in low-cost countries: the insourcer/vendor may not only offer cost advantages, but also quality improvement and innovation. The quality improvements that offshore...

Offshore Wind Turbine Foundation Design

OpenAIRE

Passon, Patrik; Branner, Kim; Larsen, Søren Ejling; Hvenekær Rasmussen, Jørgen

2015-01-01

Offshore vindenergi er i høj grad modnet i det seneste årti med en årligt installeret kapacitet på mere end1 GW. En vigtig faktor for den videre udvikling af offshore vindenergi i stor målestok, er en reduktion af de samlede udgifter til produceret energi. I betragtning af for eksempel faldet i olieprisen siden sommeren 2014 og dens fortsatte fald ind i 2015, er det endnu vigtigere at sænke omkostningerne til etablering af vedvarende energikilder såsom offshore vindenergi, for at nå frem til ...

Comparison of Welding Residual Stresses of Hybrid Laser-Arc Welding and Submerged Arc Welding in Offshore Steel Structures

DEFF Research Database (Denmark)

Andreassen, Michael Joachim; Yu, Zhenzhen; Liu, Stephen

2016-01-01

In the offshore industry, welding-induced distortion and tensile residual stresses have become a major concern in relation to the structural integrity of a welded structure. Particularly, the continuous increase in size of welded plates and joints needs special attention concerning welding induced...... residual stresses. These stresses have a negative impact on the integrity of the welded joint as they promote distortion, reduce fatigue life, and contribute to corrosion cracking and premature failure in the weld components. This paper deals with the influence and impact of welding method on the welding...... induced residual stresses. It is also investigated whether the assumption of residual stresses up to yield strength magnitude are present in welded structures as stated in the design guidelines. The fatigue strength for welded joints is based on this assumption. The two welding methods investigated...

Development of Offshore Wind Power Industry

Institute of Scientific and Technical Information of China (English)

Liu Xiao

2011-01-01

The offshore wind power development target as initially proposed in "The 12=Five-Year" on energy recourses development and renewable energy recourses currently under development is to reach 5m KW by 2015 and 30m KW by 2020. With the unfolding of offshore wind turbine planning from different areas, the curtain of offshore wind power development for our country's "The 12=Five-Year" has been opened.

Managing Risk Areas in Software Development Offshoring

DEFF Research Database (Denmark)

Persson, John Stouby; Schlichter, Bjarne Rerup

2015-01-01

Software companies are increasingly offshoring development to countries with high expertise at lower cost. Offshoring involves particular risk areas that if ignored increase the likelihood of failure. However, the offshoring client’s maturity level may influence the management of these risk areas...

The effects of meshed offshore grids on offshore wind investment – a real options analysis

DEFF Research Database (Denmark)

Schröder, Sascha Thorsten; Kitzing, Lena

2012-01-01

Offshore wind farms in future meshed offshore grids could be subject to different regulatory regimes. Feed-in tariffs would absorb market risk from wind farm operators, whereas price premium mechanisms leave operators exposed to market price signals. In this case, it plays a decisive role which...... price applies to a node in an offshore grid. The offshore node will either be integrated into any of the neighbouring markets, with access to the respective maximum price, or be subject to separate nodal pricing. We investigate the different regulatory regimes for connections to one to four countries...... based on a stochastic model capturing uncertainties in prices and line failures. The stochastic analysis shows that in case the wind park is granted access to the respective maximum price, there is a significant option value connected to the operational flexibility of accessing several markets: The wind...

The effects of meshed offshore grids on offshore wind investment – a real options analysis

DEFF Research Database (Denmark)

Schröder, Sascha Thorsten; Kitzing, Lena

2012-01-01

based on a stochastic model capturing uncertainties in prices and line failures. The stochastic analysis shows that in case the wind park is granted access to the respective maximum price, there is a significant option value connected to the operational flexibility of accessing several markets: The wind......Offshore wind farms in future meshed offshore grids could be subject to different regulatory regimes. Feed-in tariffs would absorb market risk from wind farm operators, whereas price premium mechanisms leave operators exposed to market price signals. In this case, it plays a decisive role which...... price applies to a node in an offshore grid. The offshore node will either be integrated into any of the neighbouring markets, with access to the respective maximum price, or be subject to separate nodal pricing. We investigate the different regulatory regimes for connections to one to four countries...

Offshore structural trends from magnetic data over Cauvery Basin, east coast of India

Digital Repository Service at National Institute of Oceanography (India)

Subrahmanyam, A.S.; Lakshminarayana, S.; Chandrasekhar, D.V.; Murthy, K.S.R.; Rao, T.C.S.

been interpreted as due to dyke intrusions. NE-SW lineament reflects the offshore extension of a major basement depression, viz, the Pondicherry depression. E-W lineation, south of Proto Novo reveals a basement high suggesting the seaward extension...

Spatial-temporal analysis of coherent offshore wind field structures measured by scanning Doppler-lidar

Science.gov (United States)

Valldecabres, L.; Friedrichs, W.; von Bremen, L.; Kühn, M.

2016-09-01

An analysis of the spatial and temporal power fluctuations of a simplified wind farm model is conducted on four offshore wind fields data sets, two from lidar measurements and two from LES under unstable and neutral atmospheric conditions. The integral length scales of the horizontal wind speed computed in the streamwise and the cross-stream direction revealed the elongation of the structures in the direction of the mean flow. To analyse the effect of the structures on the power output of a wind turbine, the aggregated equivalent power of two wind turbines with different turbine spacing in the streamwise and cross-stream direction is analysed at different time scales under 10 minutes. The fact of considering the summation of the power of two wind turbines smooths out the fluctuations of the power output of a single wind turbine. This effect, which is stronger with increasing spacing between turbines, can be seen in the aggregation of the power of two wind turbines in the streamwise direction. Due to the anti-correlation of the coherent structures in the cross-stream direction, this smoothing effect is stronger when the aggregated power is computed with two wind turbines aligned orthogonally to the mean flow direction.

Optimization of Support Structures for Offshore Wind Turbines Using Genetic Algorithm with Domain-Trimming

Directory of Open Access Journals (Sweden)

Mohammad AlHamaydeh

2017-01-01

Full Text Available The powerful genetic algorithm optimization technique is augmented with an innovative “domain-trimming” modification. The resulting adaptive, high-performance technique is called Genetic Algorithm with Domain-Trimming (GADT. As a proof of concept, the GADT is applied to a widely used benchmark problem. The 10-dimensional truss optimization benchmark problem has well documented global and local minima. The GADT is shown to outperform several published solutions. Subsequently, the GADT is deployed onto three-dimensional structural design optimization for offshore wind turbine supporting structures. The design problem involves complex least-weight topology as well as member size optimizations. The GADT is applied to two popular design alternatives: tripod and quadropod jackets. The two versions of the optimization problem are nonlinearly constrained where the objective function is the material weight of the supporting truss. The considered design variables are the truss members end node coordinates, as well as the cross-sectional areas of the truss members, whereas the constraints are the maximum stresses in members and the maximum displacements of the nodes. These constraints are managed via dynamically modified, nonstationary penalty functions. The structures are subject to gravity, wind, wave, and earthquake loading conditions. The results show that the GADT method is superior in finding best discovered optimal solutions.

Evaluation of Long Term Behaviour of Polymers for Offshore Oil and Gas Applications

Directory of Open Access Journals (Sweden)

Le Gac P.-Y.

2015-02-01

Full Text Available Polymers and composites are very attractive for underwater applications, but it is essential to evaluate their long term behaviour in sea water if structural integrity of offshore structures is to be guaranteed. Accelerated test procedures are frequently required, and this paper will present three examples showing how the durability of polymers, in the form of fibres, matrix resins in fibre reinforced composites for structural elements, and thermal insulation coatings of flow-lines, have been evaluated for offshore use. The influence of the ageing medium, temperature, and hydrostatic pressure will be discussed first, then an example of the application of ageing test results to predict long term behavior of the thermal insulation coating of a flowline will be presented.

Wave Run-Up on Offshore Windturbine Foundations

DEFF Research Database (Denmark)

Frigaard, Peter; De Vos, Leen

2005-01-01

In the last decade, several offshore wind-farms are built and offshore wind energy promises to be a suitable alternative to provide green energy. However, there still are some engineering challenges in placing the wind turbine foundations offshore. For example, unexpected damage to boat landing...

Issues in offshore platform research - Part 1: Semi-submersibles

Science.gov (United States)

Sharma, R.; Kim, Tae-Wan; Sha, O. P.; Misra, S. C.

2010-09-01

Availability of economic and efficient energy resources is crucial to a nation's development. Because of their low cost and advancement in drilling and exploration technologies, oil and gas based energy systems are the most widely used energy source throughout the world. The inexpensive oil and gas based energy systems are used for everything, i.e., from transportation of goods and people to the harvesting of crops for food. As the energy demand continues to rise, there is strong need for inexpensive energy solutions. An offshore platform is a large structure that is used to house workers and machinery needed to drill wells in the ocean bed, extract oil and/or natural gas, process the produced fluids, and ship or pipe them to shore. Depending on the circumstances, the offshore platform can be fixed (to the ocean floor) or can consist of an artificial island or can float. Semi-submersibles are used for various purposes in offshore and marine engineering, e.g. crane vessels, drilling vessels, tourist vessels, production platforms and accommodation facilities, etc. The challenges of deepwater drilling have further motivated the researchers to design optimum choices for semi-submersibles for a chosen operating depth. In our series of eight papers, we discuss the design and production aspects of all the types of offshore platforms. In the present part I, we present an introduction and critical analysis of semi-submersibles.

Comparison of API & IEC Standards for Offshore Wind Turbine Applications in the U.S. Atlantic Ocean: Phase II; March 9, 2009 - September 9, 2009

Energy Technology Data Exchange (ETDEWEB)

Jha, A.; Dolan, D.; Gur, T.; Soyoz, S.; Alpdogan, C.

2013-01-01

This report compares two design guidelines for offshore wind turbines: Recommended Practice for Planning, Designing, and Constructing Fixed Offshore Platform Structures and the International Electrotechnical Commission 61400-3 Design Requirements for Offshore Wind Turbines.

China: an emerging offshore wind development hotspot. With a new assessment of China's offshore wind potential

Energy Technology Data Exchange (ETDEWEB)

Reinvang, Rasmus; Enslow, Rachel; Beaumont, Hubert

2010-08-15

This study provides new and more detailed estimates of the offshore wind energy resources in China, with particular focus on Southern China. The study points out that the offshore wind industry is ramping up in China with at least 11.9GW in the development pipeline per April 2010. The study estimates the offshore wind potential of China (excluding Taiwan) to 11,580TWh/year. The study proves estimates and wind energy resource maps per province. Fujian, Zhejiang and Hainan stand out with the highest offshore wind speeds in China while Guangdong also shows significant potential, with annual wind speed averages of 6.5-10.2m/s and an energy density range of 12-36GWh/km2. Even though current offshore wind development is mainly taking place in Fujian and Jiangsu, this study shows that the potential is likely even greater in other provinces. The study was developed by the Chinese Wind Energy Association (CWEA) and Sun Yat-sen University, and commissioned by WWF as part of a project funded by the Norwegian Agency of development Coopeartion (Norad). Methodology and constraints: The wind resource analysis improves upon previous studies in estimating the wind energy generation potential for offshore wind power in China, with available meteorological data adjusted for influence of typhoons. The study models how much energy offshore wind can produce along China's coast up to 100km from the shore by calculating the energy output of theoretical wind farms by applying the power curve of a 3MW turbine at a 100m hub height. In addition the study further expands by giving special consideration to the deep-sea offshore potential at +50m water depths. The study focuses particularly on the coastline from Shandong down to Hainan. The final results provide good indication of the offshore wind resource in China when comparing one area to the other. The report can therefore be used as a preliminary tool to identifying most interesting provinces and locations for offshore wind

Application of GNSS Methods for Monitoring Offshore Platform Deformation

Science.gov (United States)

Myint, Khin Cho; Nasir Matori, Abd; Gohari, Adel

2018-03-01

Global Navigation Satellite System (GNSS) has become a powerful tool for high-precision deformation monitoring application. Monitoring of deformation and subsidence of offshore platform due to factors such as shallow gas phenomena. GNSS is the technical interoperability and compatibility between various satellite navigation systems such as modernized GPS, Galileo, reconstructed GLONASS to be used by civilian users. It has been known that excessive deformation affects platform structurally, causing loss of production and affects the efficiency of the machinery on board the platform. GNSS have been proven to be one of the most precise positioning methods where by users can get accuracy to the nearest centimeter of a given position from carrier phase measurement processing of GPS signals. This research is aimed at using GNSS technique, which is one of the most standard methods to monitor the deformation of offshore platforms. Therefore, station modeling, which accounts for the spatial correlated errors, and hence speeds up the ambiguity resolution process is employed. It was found that GNSS combines the high accuracy of the results monitoring the offshore platforms deformation with the possibility of survey.

2016 Offshore Wind Technologies Market Report

Energy Technology Data Exchange (ETDEWEB)

Musial, Walter; Beiter, Philipp; Schwabe, Paul; Tian, Tian; Stehly, Tyler; Spitsen, Paul; Robertson, Amy; Gevorgian, Vahan

2017-08-08

The 2016 Offshore Wind Technologies Market Report was developed by the National Renewable Energy Laboratory (NREL) for the U.S. Department of Energy (DOE) and is intended to provide offshore wind policymakers, regulators, developers, researchers, engineers, financiers, and supply chain participants, with quantitative information about the offshore wind market, technology, and cost trends in the United States and worldwide. In particular, this report is intended to provide detailed information on the domestic offshore wind industry to provide context to help navigate technical and market barriers and opportunities. The scope of the report covers the status of the 111 operating offshore wind projects in the global fleet through December 31, 2016, and provides the status and analysis on a broader pipeline of 593 projects at some stage of development. In addition, this report provides a wider assessment of domestic developments and events through the second quarter of 2017 to provide a more up-to-date discussion of this dynamically evolving industry.

Structure of the Lithosphere-Asthenosphere Boundary Onshore and Offshore the California Continental Margin from Three-Dimensional Seismic Anisotropy

Science.gov (United States)

Gomez, C. D.; Escobar, L., Sr.; Rathnayaka, S.; Weeraratne, D. S.; Kohler, M. D.

2016-12-01

The California continental margin, a major transform plate boundary in continental North America, is the locus of complex tectonic stress fields that are important in interpreting both remnant and ongoing deformational strain. Ancient subduction of the East Pacific Rise spreading center, the rotation and translation of tectonic blocks and inception of the San Andreas fault all contribute to the dynamic stress fields located both onshore and offshore southern California. Data obtained by the ALBACORE (Asthenospheric and Lithospheric Broadband Architecture from the California Offshore Region Experiment) and the CISN (California Integrated Seismic Network) seismic array are analyzed for azimuthal anisotropy of Rayleigh waves from 80 teleseismic events at periods 16 - 78 s. Here we invert Rayleigh wave data for shear wave velocity structure and three-dimensional seismic anisotropy in the thee regions designated within the continental margin including the continent, seafloor and California Borderlands. Preliminary results show that seismic anisotropy is resolved in multiple layers and can be used to determine the lithosphere-asthenosphere boundary (LAB) in offshore and continental regions. The oldest seafloor in our study at age 25-35 Ma indicates that the anisotropic transition across the LAB occurs at 73 km +/- 25 km with the lithospheric fast direction oriented WNW-ESE, consistent with current Pacific plate motion direction. The continent region west of the San Andreas indicates similar WNW-ESE anisotropy and LAB depth. Regions east of the San Andreas fault indicate NW-SE anisotropy transitioning to a N-S alignment at 80 km depth north of the Garlock fault. The youngest seafloor (15 - 25 Ma) and outer Borderlands indicate a more complex three layer fabric where shallow lithospheric NE-SW fast directions are perpendicular with ancient Farallon subduction arc, a mid-layer with E-W fast directions are perpendicular to remnant fossil fabric, and the deepest layer

Optimal propulsion of an undulating slender body with anisotropic friction.

Science.gov (United States)

Darbois Texier, Baptiste; Ibarra, Alejandro; Melo, Francisco

2018-01-24

This study investigates theoretically and numerically the propulsive sliding of a slender body. The body sustains a transverse and propagative wave along its main axis, and undergoes anisotropic friction caused by its surface texture sliding on the floor. A model accounting for the anisotropy of frictional forces acting on the body is implemented. This describes the propulsive force and gives the optimal undulating parameters for efficient forward propulsion. The optimal wave characteristics are effectively compared to the undulating motion of a slithering snakes, as well as with the motion of sandfish lizards swimming through the sand. Furthermore, numerical simulations have indicated the existence of certain specialized segments along the body that are highly efficient for propulsion, explaining why snakes lift parts of their body while slithering. Finally, the inefficiency of slithering as a form of locomotion to ascend a slope is discussed.

Offshore Fish Community: Ecological Interactions

Science.gov (United States)

The offshore (>80 m) fish community of Lake Superior is made up of predominately native species. The most prominent species are deepwater sculpin, kiyi, cisco, siscowet lake trout, burbot, and the exotic sea lamprey. Bloater and shortjaw cisco are also found in the offshore zone...

An Experimental Study of an Offshore Platform

DEFF Research Database (Denmark)

Brincker, Rune; Asmussen, John Christian; Andersen, Palle

of the multi-pile offshore platform is investigated by using a vibration based damage detection scheme. Changes in structural integrity are assumed to be reflected in the modal parameters estimated from only output data using an Auto-Regressive Moving Average (ARMA) model. Before the calibration of the ARMA...... model the quality of the measured data have been investigated. The estimated modal parameters and their corresponding variances are used as input to a probability based damage indicator. This indicator indicates, that since the construction of the platform, minor structural changes have taken place....

Elastogranular Mechanics: Buckling, Jamming, and Structure Formation

Science.gov (United States)

Schunter, David J.; Brandenbourger, Martin; Perriseau, Sophia; Holmes, Douglas P.

2018-02-01

Confinement of a slender body into a granular array induces stress localization in the geometrically nonlinear structure, and jamming, reordering, and vertical dislodging of the surrounding granular medium. By varying the initial packing density of grains and the length of a confined elastica, we identify the critical length necessary to induce jamming, and demonstrate how folds couple with the granular medium to localize along grain boundaries. Above the jamming threshold, the characteristic length of elastica deformation is shown to diverge in a manner that is coupled with the motion and rearrangement of the grains, suggesting the ordering of the granular array governs the deformation of the slender structure. However, overconfinement of the elastica will vertically dislodge grains, a form of stress relaxation in the granular medium that illustrates the intricate coupling in elastogranular interactions.

Elastogranular Mechanics: Buckling, Jamming, and Structure Formation.

Science.gov (United States)

Schunter, David J; Brandenbourger, Martin; Perriseau, Sophia; Holmes, Douglas P

2018-02-16

Confinement of a slender body into a granular array induces stress localization in the geometrically nonlinear structure, and jamming, reordering, and vertical dislodging of the surrounding granular medium. By varying the initial packing density of grains and the length of a confined elastica, we identify the critical length necessary to induce jamming, and demonstrate how folds couple with the granular medium to localize along grain boundaries. Above the jamming threshold, the characteristic length of elastica deformation is shown to diverge in a manner that is coupled with the motion and rearrangement of the grains, suggesting the ordering of the granular array governs the deformation of the slender structure. However, overconfinement of the elastica will vertically dislodge grains, a form of stress relaxation in the granular medium that illustrates the intricate coupling in elastogranular interactions.

Offshore wind power in Finland

Energy Technology Data Exchange (ETDEWEB)

Holttinen, H. [VTT Energy, Espoo (Finland)

1998-12-31

The objectives of the project were to estimate the technical offshore wind power potential of the Gulf of Bothnia, with cost assessments, to study icing conditions and ice loads, and to design a foundation suitable for the environmental conditions. The technical offshore potential from Vaasa to Tornio is huge, more than 40 TWh/a, although the cost of offshore wind power is still higher than on land. Wind turbines have not previously been designed for the icing conditions found in Gulf of Bothnia and the recommendations for load cases and siting of megawatt-class turbines are an important result of the project. (orig.)

Offshore Wind Energy Cost Modeling Installation and Decommissioning

CERN Document Server

Kaiser, Mark J

2012-01-01

Offshore wind energy is one of the most promising and fastest growing alternative energy sources in the world. Offshore Wind Energy Cost Modeling provides a methodological framework to assess installation and decommissioning costs, and using examples from the European experience, provides a broad review of existing processes and systems used in the offshore wind industry. Offshore Wind Energy Cost Modeling provides a step-by-step guide to modeling costs over four sections. These sections cover: ·Background and introductory material, ·Installation processes and vessel requirements, ·Installation cost estimation, and ·Decommissioning methods and cost estimation.  This self-contained and detailed treatment of the key principles in offshore wind development is supported throughout by visual aids and data tables. Offshore Wind Energy Cost Modeling is a key resource for anyone interested in the offshore wind industry, particularly those interested in the technical and economic aspects of installation and decom...

Grid Integration of Offshore Wind | Wind | NREL

Science.gov (United States)

Grid Integration of Offshore Wind Grid Integration of Offshore Wind Much can be learned from the existing land-based integration research for handling the variability and uncertainty of the wind resource Arklow Bank offshore wind park consists of seven GE Wind 3.6-MW wind turbines. Integration and

Conference on offshore wind power in France and Germany

International Nuclear Information System (INIS)

Meyer, Ronny; Furois, Timothee; Nolte, Nico; Lanoe, Frederic; Lehmann-Matthaei, Bjoern; Ifflaender, Andree; Courcambeck, Alexandre; Giese, Norbert; Kavafyan, Philippe; Bjaert, Niels; Wagner, Andreas; Guillet, Jerome

2014-01-01

The French-German office for Renewable energies (OFAEnR) organised a conference on offshore wind power in France and Germany. In the framework of this French-German exchange of experience, about 120 participants exchanged views on the planning and authorisation procedures implemented in both countries and on the installation, connection to the grid and maintenance of offshore wind turbines. environmental impacts and usage conflicts linked with offshore wind farms exploitation were addressed as well. This document brings together the available presentations (slides) made during this event: 1 - Update: Offshore Wind In Germany (Ronny Meyer); 2 - Offshore wind development in France (Timothee Furois); 3 - The Licensing Procedure for Offshore Wind Farms in the German EEZ (Nico Nolte); 4 - Spatial Planning and Permitting in France: What leverage for more efficiency? (Frederic Lanoe); 5 - Results of 10 years environmental research on FINO-platforms (Bjoern Lehmann-Matthaei); 6 - Offshore Grid Connection - Status Quo and Overview (Andree Ifflaender); 7 - Grid connection of Offshore Wind in France: Situation, perspectives and recommendations (Alexandre Courcambeck); 8 - Controlling risks and warranting safety: Best practices for the installation, exploitation and maintenance of offshore wind turbines (Norbert Giese); 9 - Offshore wind Bremerhaven experience: An essential asset for the development of a complete Wind Offshore industry in France (Philippe Kavafyan); 10 - Standardizing and Cost Reduction -Lessons Learned from London Array (Niels Bjaert); 11 - Offshore Wind energy in Germany: System Benefits and Cost Reduction Potentials. Presentation of study results from prognos/fichtner and Fraunhofer-IWeS (Andreas Wagner); 12 - Offshore Wind energy financing - opportunities and risks (Jerome Guillet)

Denmark - supplier of competitive offshore wind solutions. Megavind's strategy for offshore wind research, development and demonstration

Energy Technology Data Exchange (ETDEWEB)

2010-12-15

In May 2006, the Danish Government presented a report on promoting environmentally effective technology and established a number of innovative partnerships. The partnerships intend to strengthen public-private cooperation between the state, industry, universities and venture capital to accelerate innovation for a number of green technologies. The partnership for wind energy is called Megavind. Megavind's strategy for offshore wind describes the offshore challenges and suggests research, development and demonstration (RD and D) priorities to enable offshore wind power become to competitive with other energy technologies. The strategy lists key recommendations as well as key thematic priorities and for each of these a number of RD and D priorities. Under each thematic priority references are made to the European Strategic Energy Technology plan (SET-plan), which prioritises offshore wind RD and D in Europe. (LN)

Grid-connection of offshore wind farms using VSC-HVDC systems

Energy Technology Data Exchange (ETDEWEB)

Fu, Xiaofan; Dessaint, Louis A. [Ecole de Technologie Superieure, Montreal, QC (Canada). Dept. of Electrical Engineering; Gagnon, Richard [Hydro-Quebec Research Institute, Montreal, QC (Canada)

2011-07-01

In this paper, the structure of variable speed PMSG-based offshore wind farms connected to the grid through VSC-HVDC link is presented. And the system models are developed. Also, the corresponding control strategy for this system is proposed. The control objective of the generator side VSC is to achieve the optimal wind power by adjusting the speed of permanent magnet synchronous generator, while the grid side VSC is to maintain DC voltage constant. Furthermore, a case study of 100MW offshore wind farm consisting of 50 individual 2MW PSMG-based wind turbines is developed in MATLAB/SimPowerSystems. Simulation results show the proposed scheme works well. (orig.)

The offshore benthic fish community

Science.gov (United States)

Lantry, Brian F.; Lantry, Jana R.; Weidel, Brian C.; Walsh, Maureen; Hoyle, James A.; Schaner, Teodore; Neave, Fraser B.; Keir, Michael

2014-01-01

Lake Ontario’s offshore benthic fish community includes primarily slimy sculpin, lake whitefish, rainbow smelt, lake trout, burbot, and sea lamprey. Of these, lake trout have been the focus of an international restoration effort for more than three decades (Elrod et al. 1995; Lantry and Lantry 2008). The deepwater sculpin and three species of deepwater ciscoes (Coregonus spp.) that were historically important in the offshore benthic zone became rare or were extirpated by the 1960s (Christie 1973; Owens et al. 2003; Lantry et al. 2007b; Roth et al. 2013). Ecosystem changes continue to influence the offshore benthic fish community, including the effects of dreissenid mussels, the near disappearance of burrowing amphipods (Diporeia spp.) (Dermott et al. 2005; Watkins et al. 2007), and the increased abundance and expanded geographic distribution of round goby (see Nearshore Fish Community chapter) (Lantry et al. 2007b). The fish-community objectives for the offshore benthic fish community, as described by Stewart et al. (1999), are:

IFREMER-ADEME colloquium 'Offshore renewable energies: offshore wind energy - sea currents and waves. Collection of abstracts

International Nuclear Information System (INIS)

2004-10-01

This document contains programme and abstracts of contributions presented during a colloquium. These contributions first addresses the context, and regulatory and economic aspects of offshore wind and sea energy: specificities related to the Public Maritime Domain for the implantation of offshore wind turbines, economy of sea energies within a perspective of de-carbonation of the world energy sector, case of offshore wind turbines and assessment of economic impacts of the implantation of sea renewable energy production units, financing stakes for offshore wind energy projects. A second set of contribution addresses the state-of -the-art and feedbacks for offshore wind energy installations. The third set addresses the assessment of resource potential, measurements, models and production prediction for offshore wind energy: case of French coasts, use of radar for remote sensing, wind climatology modelling, data acquisition for wind farm and data processing. The fourth set of contributions addresses the state-of-the-art, feedback, and R and D for sea current energy, while the fifth one addressed the same aspects for sea wave energy. Technology, installations, maintenance and storage in the field of wind energy are then addressed, and the last set deals with environmental and social-economical impacts of sea renewable energies

The onshore influence of offshore fresh groundwater

Science.gov (United States)

Knight, Andrew C.; Werner, Adrian D.; Morgan, Leanne K.

2018-06-01

Freshwater contained within the submarine extensions of coastal aquifers is increasingly proposed as a freshwater source for coastal communities. However, the extent to which offshore freshwater supports onshore pumping is currently unknown on a global scale. This study provides the first attempt to examine the likely prevalence of situations where offshore freshwater influences onshore salinities, considering various sites from around the world. The groundwater conditions in twenty-seven confined and semi-confined coastal aquifers with plausible connections to inferred or observed offshore freshwater are explored. The investigation uses available onshore salinities and groundwater levels, and offshore salinity knowledge, in combination with analytical modelling, to develop simplified conceptual models of the study sites. Seven different conceptual models are proposed based on the freshwater-saltwater extent and insights gained from analytical modelling. We consider both present-day and pre-development conditions in assessing potential modern contributions to offshore fresh groundwater. Conceptual models also include interpretations of whether offshore freshwater is a significant factor influencing onshore salinities and well pumping sustainability. The results indicate that onshore water levels have declined between pre-development and present-day conditions in fourteen of the fifteen regions for which pre-development data are available. Estimates of the associated steady-state freshwater extents show the potential for considerable offshore fresh groundwater losses accompanying these declines. Both present-day and pre-development heads are insufficient to account for the observed offshore freshwater in all cases where adequate data exist. This suggests that paleo-freshwater and/or aquifer heterogeneities contribute significantly to offshore freshwater extent. Present-day heads indicate that active seawater intrusion (SWI) will eventually impact onshore pumping

Understanding public responses to offshore wind power

International Nuclear Information System (INIS)

Haggett, Claire

2011-01-01

This paper is about understanding the role and importance of public responses to offshore wind power. It builds on a framework for understanding social acceptance and opposition to onshore turbines, and reviews the emerging research on offshore wind. While less is known about how people will respond to offshore than onshore wind, there is now an emerging body of research. From this literature, several common factors which influence responses have emerged and are discussed here: the (continued) role of visual impact; place attachment to the local area; lack of tangible benefits; relationships with developers and outsiders; and the role of the planning and decision-making systems. The paper argues that, as with onshore developments, the public should be included in decision-making about offshore wind farms, and that they have a key role which should not be underestimated. The paper concludes with some thoughts about the means to involve people and how effected communities might be effectively acknowledged, identified and engaged. - Research Highlights: →Comprehensive review of public responses to offshore wind literature. →Applies key lessons and analytic insights from onshore wind to offshore wind. →Emphasizes the role and importance of the public in the planning and implementation of offshore wind energy.

Global Production: The Case of Offshore Programming

DEFF Research Database (Denmark)

Nørbjerg, Jacob; Havn, Erling; Bansler, Jørgen P.

1997-01-01

of software is no exception.In this paper, we present a newly started research project on offshore program-ming, that is the practice of sending software development “offshore,” to India or other low wage areas. The project focuses on the organisation of offshore program-ming and, particularly, on the role...

Development of fast wireless detection system for fixed offshore platform

Science.gov (United States)

Li, Zhigang; Yu, Yan; Jiao, Dong; Wang, Jie; Li, Zhirui; Ou, Jinping

2011-04-01

Offshore platforms' security is concerned since in 1950s and 1960s, and in the early 1980s some important specifications and standards are built, and all these provide technical basis of fixed platform design, construction, installation and evaluation. With the condition that more and more platforms are in serving over age, the research about the evaluation and detection technology of offshore platform has been a hotspot, especially underwater detection, and assessment method based on the finite element calculation. For fixed platform structure detection, conventional NDT methods, such as eddy current, magnetic powder, permeate, X-ray and ultrasonic, etc, are generally used. These techniques are more mature, intuitive, but underwater detection needs underwater robot, the necessary supporting tools of auxiliary equipment, and trained professional team, thus resources and cost used are considerable, installation time of test equipment is long. This project presents a new kind of fast wireless detection and damage diagnosis system for fixed offshore platform using wireless sensor networks, that is, wireless sensor nodes can be put quickly on the offshore platform, detect offshore platform structure global status by wireless communication, and then make diagnosis. This system is operated simply, suitable for offshore platform integrity states rapid assessment. The designed system consists in intelligence acquisition equipment and 8 wireless collection nodes, the whole system has 64 collection channels, namely every wireless collection node has eight 16-bit accuracy of A/D channels. Wireless collection node, integrated with vibration sensing unit, embedded low-power micro-processing unit, wireless transceiver unit, large-capacity power unit, and GPS time synchronization unit, can finish the functions such as vibration data collection, initial analysis, data storage, data wireless transmission. Intelligence acquisition equipment, integrated with high

Socio-economic Impacts—Offshore Activities/Energy

DEFF Research Database (Denmark)

Halsnæs, Kirsten; Drews, Martin; Clausen, Niels-Erik

2016-01-01

sector and renewable electricity generation—mainly from offshore wind—is increasing. Energy and offshore activities in the North Sea are critically vulnerable to climate change along the full supply chain. The major vulnerabilities for offshore installations like rigs, offshore wind energy and pipelines......, it is highly uncertain how much the future potential of other renewable energy sources such as wind, solar, terrestrial biomass, or emerging technologies like wave, tidal or marine biomass could be positively or negatively affected. Due to the different national energy supply mixes the vulnerability to climate......-related impacts will vary among North Sea countries. To ensure safe and reliable future operations comprehensive and systematic risk assessments are therefore needed which account for, for example, the high integration of power systems in the region....

Point-based POMDP Risk Based Inspection of Offshore Wind Substructures

DEFF Research Database (Denmark)

Morato, Pablo G.; Mai, Quang A.; Rigo, Philippe

2018-01-01

This article presents a novel methodology to select the optimal maintenance strategy of an offshore wind structural component, providing a flexible and reliable support to decision-making and balancing inspection, repair and failure costs. The procedure to create a “Point-Based” Partially...

The north-east Baffin Bay region, offshore Greenland - a new frontier petroleum exploration region

Energy Technology Data Exchange (ETDEWEB)

Gregersen, U. (Geological Survey of Denmark and Greenland, Copenhagen (Denmark))

2008-07-15

In recent years the Arctic has come into focus for hydrocarbon exploration, and areas offshore both West and East Greenland have been evaluated as promising frontier hydrocarbon provinces. Seven hydrocarbon exploration and exploitation licenses were awarded in 2007-2008 offshore the Disko-Nuussuaq region, and two more have been awarded in the open-door region offshore south-western Greenland. In 2007, an extensive amount of new seismic and aero-magnetic data was acquired by the TGS-NOPEC Geophysical Company in the north-eastern Baffin Bay region. Geophysical mapping has been initiated by the Geological Survey of Denmark and Greenland (GEUS) in the Melville Bugt region offshore North-West Greenland with the purpose of evaluating the hydrocarbon prospectivity. Initial interpretation of seismic and gravity data suggests the presence of deep sedimentary basins separated by structural highs. Geological information on source rock, reservoir rock and seal intervals from surrounding regions suggest that the Melville Bugt region is likely to have a significant petroleum potential. The study is based on public domain magnetic and gravity data, and all proprietary and public 2-D seismic data acquired before 2003. Seismic horizons from the 'seismic basement' to 'base Quaternary' are being interpreted regionally. Based on the seismic interpretation, a structural element map, depth-structure maps and isopach maps will be produced in order to assess the prospectivity of the Melville Bugt region. (au)

Risk-Based Operation and Maintenance Planning for Offshore Wind Turbines

DEFF Research Database (Denmark)

Nielsen, Jannie Jessen; Sørensen, John Dalsgaard

2010-01-01

Operation and maintenance (O&M) are large contributors to the cost of energy for offshore wind turbines. Optimal planning of O&M should include use of inspections and monitoring results to make decisions that minimize the expected costs through the lifetime of the structures. For offshore...... structures it is especially important because of the dependence on weather windows for inspections and repairs to be possible. A model has been developed to estimate the expected costs to corrective and condition based maintenance for a wind turbine with a single component. The deterioration of the component...... is simulated, and the expected costs are found for different strategies. An application example shows that condition based maintenance has the potential of reducing the costs, and a risk based approach can be used to find the optimal strategy for O&M. Further the influence of failure rate and damage parameters...

Fine Slicing of the Value Chain and Offshoring of Essential Activities

DEFF Research Database (Denmark)

Linares-Navarro, Esmeralda; Pedersen, Torben; Pla-Barber, José

2014-01-01

The offshoring of more advanced activities is increasing and a debate about the limits of offshoring has emerged. Companies are fine-slicing their value chains, and moving beyond the offshoring of peripheral and non-core activities to the offshoring of advanced and essential activities that are c......The offshoring of more advanced activities is increasing and a debate about the limits of offshoring has emerged. Companies are fine-slicing their value chains, and moving beyond the offshoring of peripheral and non-core activities to the offshoring of advanced and essential activities...... that companies are redefining their core activities and in this process, some essential activities previously viewed as core activities are being detached from the core, and they become more offshorable. The study uses a sample of 565 offshoring operations conducted by 263 multinational companies from 15...... European countries. A logistic regression was used to analyze the relationship between the activities offshored (non-core versus essential activities) and the offshoring mode implemented (captive offshoring versus offshore outsourcing). We find that essential activities are typically offshored using...

BUSINESS OFFSHORING IMPLICATIONS ON THE LABOUR MARKET

Directory of Open Access Journals (Sweden)

SERGHEI MARGULESCU

2012-05-01

Full Text Available In terms of economic policy, three new aspects are important in the current context of globalization which brings forward new strategies regarding the outsourcing and offshoring of activities and functions of the value chain. These aspects refer to the instant appearance of an offshore transferable function , to the unpredictability of winning and losing functions and to the lowering of competition from the levels of sector, company or professional qualification category to an individual level. Of the three features, the most problematic for policy makers is the unpredictability of the impact of globalization. For example, in Europe we can not reasonably believe that workers in the most competitive sectors will be in a position of winners, nor that these winners will be the most prepared or trained in analytical functions. Many European workers currently work at prices fixed by the local market and not covered by productivity. But when the competition on functions will expand through globalization outside the country or area, their choices will be either a job loss or a reduction in salary. The question that will be raised ever insistently will be the following: what jobs are more exposed to this new competition? On the one hand, offshoring is on balance positive for Western economies, because it makes domestic companies more competitive. At the same time the material outsourcing is, for most developed economies, much more important than the outsourcing of services and the implications for labor market must be objectively differentiated in the two sectors. On the other hand, if we take into account the amplification of the effects that offshoring already has on the structure and distribution of labor, the socio-economic European policy of labor orientation to the coordinates of a "knowledge based" economy and to the jobs of the "information society" could be wrong.

Offshore Supply Industry Dynamics

DEFF Research Database (Denmark)

Roslyng Olesen, Thomas

This report is part of the research project “The competitive challenges and strategic development possibilities for The Blue Denmark”, which was launched in 2014. The project is funded by the Danish Maritime Fund and carried out by researchers at CBS Maritime which is a Business in Society Platform...... with companies in the maritime sector. This report “Offshore Supply Industry Dynamics – Business strategies in the offshore supply industry” is the second report in mapping project D. It examines the markets and business strategies of various suppliers and furthermore presents an analysis of the challenges...... at Copenhagen Business School with a focus on value creation in the maritime industries. The project embraces various maritime segments from shipping and offshore to ports and suppliers. The research questions for the individual projects have been formulated by researchers at CBS Maritime in cooperation...

Gela offshore field

Energy Technology Data Exchange (ETDEWEB)

Pagliughi, G

1965-06-01

The field of Gela, off the southern shore of Sicily, is the only producing offshore field in the Mediterranean. It produces from Triassic dolimite limestones of 434-m thickness, water level at -3517 m. It is a water-drive reservoir producing 10/sup 0/F API oil and has 79 wells, some of them on shore. Most offshore wells are directional wells from shore; there are also 2 fixed platforms and a special mobile platform. The wells are on pump (stroke, 72 in.; capacity 200 tons per day). The crude goes directly to a combination refinery-petrochemical complex at Gela.

Offshore Energy Knowledge Exchange Workshop Report

Energy Technology Data Exchange (ETDEWEB)

none,

2012-04-12

A report detailing the presentations and topics discussed at the Offshore Energy Knowledge Exchange Workshop, an event designed to bring together offshore energy industry representatives to share information, best practices, and lessons learned.

Condensation of long-term wave climates for the fatigue design of hydrodynamically sensitive offshore wind turbine support structures

DEFF Research Database (Denmark)

Passon, Patrik; Branner, Kim

2016-01-01

important for hydrodynamically sensitive structures since the applied met-ocean parameters have a non-linear influence on calculated fatigue design loads. The present article introduces a new wave lumping method for condensation of the wave climate. The novelty is predominantly based on refined equivalence......Cost-efficient and reliable fatigue designs of offshore wind turbine support structures require an adequate representation of the site-specific wind–wave joint distribution. Establishment of this wind–wave joint distribution for design load calculation purposes requires typically a correlation...... of the marginal wind and wave distribution. This is achieved by condensation of the site-specific wave climate in terms of wave period or wave height lumping, subsequently used as input for a correlation with the corresponding wind climate. The quality of this resulting wind–wave correlation is especially...

Attitude and acceptance of offshore wind farms

DEFF Research Database (Denmark)

Ladenburg, Jacob; Möller, B.

2011-01-01

farms attributes on attitude towards offshore wind farms. The results point towards that the travel time and the attributes of the nearest offshore wind farm influence the attitude significantly. Travel time has mixed effects on the attitude, whilst offshore wind farms with many turbines generate more...... a novel contribution to this field. First of all, we give a thorough review of the studies that have analysed the relation between experience with wind turbines and attitude. In addition, we supplement the review by analysing the effect of travel distance to the nearest offshore wind farm and the wind...

The Capabilities of the Offshore Middlemen

DEFF Research Database (Denmark)

Mahnke, Volker; Wareham, Jonathan

preliminary theoretical justification for the emergence of offshore intermediaries; describe how and why they develop intermediation capabilities; and offer initial evidence substantiating their function and processes in intermediating transnational offshoring relationships in software development...

Issues in offshore platform research - Part 1: Semi-submersibles

Directory of Open Access Journals (Sweden)

R. Sharma

2010-09-01

Full Text Available Availability of economic and efficient energy resources is crucial to a nation's development. Because of their low cost and advancement in drilling and exploration technologies, oil and gas based energy systems are the most widely used energy source throughout the world. The inexpensive oil and gas based energy systems are used for everything, i.e., from transportation of goods and people to the harvesting of crops for food. As the energy demand continues to rise, there is strong need for inexpensive energy solutions. An offshore platform is a large structure that is used to house workers and machinery needed to drill wells in the ocean bed, extract oil and/or natural gas, process the produced fluids, and ship or pipe them to shore. Depending on the circumstances, the offshore platform can be fixed (to the ocean floor or can consist of an artificial island or can float. Semi-submersibles are used for various purposes in offshore and marine engineering, e.g. crane vessels, drilling vessels, tourist vessels, production platforms and accommodation facilities, etc. The challenges of deepwater drilling have further motivated the researchers to design optimum choices for semi-submersibles for a chosen operating depth. In our series of eight papers, we discuss the design and production aspects of all the types of offshore platforms. In the present part I, we present an introduction and critical analysis of semi-submersibles.

Offshore oil and gas activities in the PERD program

Energy Technology Data Exchange (ETDEWEB)

Billette, N. [Natural Resources Canada, Ottawa, ON (Canada). Office of Energy Research and Development

2001-07-01

Natural Resources Canada manages the Program of Energy Research and Development (PERD), which covers all but a few of non-nuclear energy areas. The aim of the Program is to focus on research and technology developments that support a dynamic and diversified energy supply, while encouraging industries to consume the energy efficiently. Twelve federal departments and agencies are stakeholders in energy research and development and the 57 million dollar annual budget is allocated amongst the stakeholders according to the priorities established. Each year, one-quarter of the program is evaluated externally and potential reallocation examined, a recent initiative implemented as part of a results-based management (RBM) system. Five federal departments and one agency carry out offshore research and development activities, touching the fields of basin assessment and geotechnics in the Canadian North and offshore East Coast, winds-wave-current modelling, the management of sea ice, iceberg and ice-structure interactions, ship design and navigation issues. In this last category, activities related to offshore safety, management of offshore drilling and production wastes, oil spills remediation, and assessment of cumulative effects of wastes and produced waters are included. These activities are detailed in the presentation, and the author discussed the future shifts likely to occur in PERD so that the needs of the regulatory agencies in terms of science and technology are met. There is also the aspect of the protection of the interests of the Canadian public to consider. 1 tab.

Environmental risk in the offshore industry

International Nuclear Information System (INIS)

Woods, I.T.; Shirley, D.; Bottelberghs, P.H.

1991-01-01

The subject of oil pollution of the sea by the offshore industry is topical as a result of recent incidents both in the U.K. and overseas. While these incidents have primarily involved crude carriers, it has led to pressure to quantify the risk to the environment from the offshore industry in general. In this paper a method for the assessment of the frequency and size of oil spills from offshore installations is presented. It relies on previously reported spills to determine spill size/frequency information for a range of offshore activities, such as transport by pipeline, drilling and processing. Modification factors are used so local conditions, such as the number of wells drilled, throughput and well depth, can be considered in the assessment of the oil spill risk from a particular installation

RAMSI management model and evaluation criteria for Nordic offshore wind asset

Energy Technology Data Exchange (ETDEWEB)

Tiusanen, R.; Jaennes, J. [VTT Technical Research Centre of Finland, Espoo (Finland); Liyanage, J. P. [Univ. of Stavanger, Center for Industrial Asset Management (Norway)

2012-07-01

The offshore wind energy sector is in the early stages of development, but it is growing fast. Due to the European Union's renewable-energy and climate goals along with national legislation, the offshore wind sector will develop strongly over the coming years in Europe. In the offshore wind energy sector, there are many different wind-turbine designs ranging from traditional mono pile structures to floating platforms, depending on the water depth. Today, most offshore turbines are based on onshore turbine designs, and turbine technology continues to develop incrementally. At the same time, there is strong demand in the market for new, innovative designs for offshore wind turbines whose main focus is reliability and cost efficiency. For floating offshore wind turbine designs, there may be new types of uncertainty and system risks compared with onshore wind turbines. Wind turbines in cold climates, such as those experienced in the Nordic countries, may be exposed to extreme conditions, such as formation of ice or very low temperatures that are outside the design limits of standard wind turbines. In the offshore wind energy sector, specification, implementation and verification of the so-called R&M's (Reliability, Availability, Maintainability, Safety and Inspect ability) requirements during development work are important for companies delivering wind turbines, from the perspective of system integrity. Decisions made before the formal design phase strongly determine the costs and benefits gained during the whole life cycle of a wind turbine. The benefits of implementing the R&M's program include support with investment decisions, cost management, improved management of resource requirements, systematic support with development and implementation of products, and integration of dependability and safety requirements. This publication outlines a model for managing R&M's factors during the conceptual design phase of an offshore wind turbine. The model

Motion Performance and Mooring System of a Floating Offshore Wind Turbine

Institute of Scientific and Technical Information of China (English)

Jing Zhao; Liang Zhang; Haitao Wu

2012-01-01

The development of offshore wind farms was originally carried out in shallow water areas with fixed (seabed mounted) structures.However,countries with limited shallow water areas require innovative floating platforms to deploy wind turbines offshore in order to harness wind energy to generate electricity in deep seas.The performances of motion and mooring system dynamics are vital to designing a cost effective and durable floating platform.This paper describes a numerical model to simulate dynamic behavior of a new semi-submersible type floating offshore wind turbine (FOWT) system.The wind turbine was modeled as a wind block with a certain thrust coefficient,and the hydrodynamics and mooring system dynamics of the platform were calculated by SESAM software.The effect of change in environmental conditions on the dynamic response of the system under wave and wind loading was examined.The results indicate that the semi-submersible concept has excellent performance and SESAM could be an effective tool for floating wind turbine design and analysis.

Motion performance and mooring system of a floating offshore wind turbine

Science.gov (United States)

Zhao, Jing; Zhang, Liang; Wu, Haitao

2012-09-01

The development of offshore wind farms was originally carried out in shallow water areas with fixed (seabed mounted) structures. However, countries with limited shallow water areas require innovative floating platforms to deploy wind turbines offshore in order to harness wind energy to generate electricity in deep seas. The performances of motion and mooring system dynamics are vital to designing a cost effective and durable floating platform. This paper describes a numerical model to simulate dynamic behavior of a new semi-submersible type floating offshore wind turbine (FOWT) system. The wind turbine was modeled as a wind block with a certain thrust coefficient, and the hydrodynamics and mooring system dynamics of the platform were calculated by SESAM software. The effect of change in environmental conditions on the dynamic response of the system under wave and wind loading was examined. The results indicate that the semi-submersible concept has excellent performance and SESAM could be an effective tool for floating wind turbine design and analysis.

Design Loads on Platforms on Offshore wind Turbine Foundations with Respect to Vertical Wave Run-up

DEFF Research Database (Denmark)

Damsgaard, Mathilde L.; Gravesen, Helge; Andersen, Thomas Lykke

2007-01-01

reduction in the loads by up to 75%. Furthermore it is indicated, that the fact that offshore wind turbines often are placed on limited water depths thereby increasing the amount of (nearly) breaking waves, seems to increase the run-up height and thereby the pressures on the structure.......Experiences have shown that the vertical run-up generated by waves meeting the offshore wind turbine foundations, can result in rather vigorous loads on appurtenances and platform structures. This study aims to provide a qualitative method of determining run-up height and the following loads...

10 CFR 150.7 - Persons in offshore waters not exempt.

Science.gov (United States)

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Persons in offshore waters not exempt. 150.7 Section 150.7... AGREEMENT STATES AND IN OFFSHORE WATERS UNDER SECTION 274 Continued Commission Regulatory Authority in Offshore Waters § 150.7 Persons in offshore waters not exempt. Persons in offshore waters are not exempt...

Stochastic dynamic stiffness of surface footing for offshore wind turbines

DEFF Research Database (Denmark)

Vahdatirad, Mohammadjavad; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo

2014-01-01

Highlights •This study concerns the stochastic dynamic stiffness of foundations for large offshore wind turbines. •A simple model of wind turbine structure with equivalent coupled springs at the base is utilized. •The level of uncertainties is quantified through a sensitivity analysis. •Estimation...

Development and application of an analysis of axisymmetric body effects on helicopter rotor aerodynamics using modified slender body theory

Science.gov (United States)

Yamauchi, G.; Johnson, W.

1984-01-01

A computationally efficient body analysis designed to couple with a comprehensive helicopter analysis is developed in order to calculate the body-induced aerodynamic effects on rotor performance and loads. A modified slender body theory is used as the body model. With the objective of demonstrating the accuracy, efficiency, and application of the method, the analysis at this stage is restricted to axisymmetric bodies at zero angle of attack. By comparing with results from an exact analysis for simple body shapes, it is found that the modified slender body theory provides an accurate potential flow solution for moderately thick bodies, with only a 10%-20% increase in computational effort over that of an isolated rotor analysis. The computational ease of this method provides a means for routine assessment of body-induced effects on a rotor. Results are given for several configurations that typify those being used in the Ames 40- by 80-Foot Wind Tunnel and in the rotor-body aerodynamic interference tests being conducted at Ames. A rotor-hybrid airship configuration is also analyzed.

Analysis of the Nonlinear Static and Dynamic Behavior of Offshore Structures

KAUST Repository

Alfosail, Feras

2015-07-01

Understanding static and dynamic nonlinear behavior of pipes and risers is crucial for the design aspects in offshore engineering fields. In this work, we examine two nonlinear problems in offshore engineering field: vortex Induced vibration of straight horizontal pipes, and boundary layer static solution of inclined risers. In the first study, we analyze the effect of the internal velocity of straight horizontal pipe and obtain the vortex induced vibration forces via coupling the pipe equation of motion with the recently modified Van Der Pol oscillator governing the lift coefficient. Our numerical results are obtained for two different pipe configurations: hinged-hinged, and clamped- clamped. The results show that the internal velocity reduces the vibration and the oscillation amplitudes. Also, it is shown that the clamped-clamped pipe configuration offers a wider range of internal velocities before buckling instability occurs. The results also demonstrate the effect of the end condition on the amplitudes of vibration. In the second study, we develop a boundary layer perturbation static solution to govern and simulate the static behavior of inclined risers. In the boundary layer analysis, we take in consideration the effects of the axial stretch, applied tension, and internal velocity. Our numerical simulation results show good agreement with the exact solutions for special cases. In addition, our developed method overcomes the mathematical and numerical limitations of the previous methods used before.

Enhanced Structural Interpretation Using Multitrace Seismic Attribute For Oligo-Miocene Target at Madura Strait Offshore

Science.gov (United States)

Pratama Wahyu Hidayat, Putra; Hary Murti, Antonius; Sudarmaji; Shirly, Agung; Tiofan, Bani; Damayanti, Shinta

2018-03-01

Geometry is an important parameter for the field of hydrocarbon exploration and exploitation, it has significant effect to the amount of resources or reserves, rock spreading, and risk analysis. The existence of geological structure or fault becomes one factor affecting geometry. This study is conducted as an effort to enhance seismic image quality in faults dominated area namely offshore Madura Strait. For the past 10 years, Oligo-Miocene carbonate rock has been slightly explored on Madura Strait area, the main reason because migration and trap geometry still became risks to be concern. This study tries to determine the boundary of each fault zone as subsurface image generated by converting seismic data into variance attribute. Variance attribute is a multitrace seismic attribute as the derivative result from amplitude seismic data. The result of this study shows variance section of Madura Strait area having zero (0) value for seismic continuity and one (1) value for discontinuity of seismic data. Variance section shows the boundary of RMKS fault zone with Kendeng zone distinctly. Geological structure and subsurface geometry for Oligo-Miocene carbonate rock could be identified perfectly using this method. Generally structure interpretation to identify the boundary of fault zones could be good determined by variance attribute.

High-resolution computational algorithms for simulating offshore wind turbines and farms: Model development and validation

Energy Technology Data Exchange (ETDEWEB)

Calderer, Antoni [Univ. of Minnesota, Minneapolis, MN (United States); Yang, Xiaolei [Stony Brook Univ., NY (United States); Angelidis, Dionysios [Univ. of Minnesota, Minneapolis, MN (United States); Feist, Chris [Univ. of Minnesota, Minneapolis, MN (United States); Guala, Michele [Univ. of Minnesota, Minneapolis, MN (United States); Ruehl, Kelley [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Guo, Xin [Univ. of Minnesota, Minneapolis, MN (United States); Boomsma, Aaron [Univ. of Minnesota, Minneapolis, MN (United States); Shen, Lian [Univ. of Minnesota, Minneapolis, MN (United States); Sotiropoulos, Fotis [Stony Brook Univ., NY (United States)

2015-10-30

The present project involves the development of modeling and analysis design tools for assessing offshore wind turbine technologies. The computational tools developed herein are able to resolve the effects of the coupled interaction of atmospheric turbulence and ocean waves on aerodynamic performance and structural stability and reliability of offshore wind turbines and farms. Laboratory scale experiments have been carried out to derive data sets for validating the computational models.

Water-hydraulic power transmission for offshore wind farms

NARCIS (Netherlands)

Diepeveen, N.F.B.; Jarquin Laguna, A.; Kempenaar, A.S.

2012-01-01

The current state of the art of offshore wind turbine power transmission technology is expensive, heavy and maintenance intensive. The Delft Offshore Turbine project considers a radically new concept for power transmission in an offshore wind farm: using seawater as power transmission medium. For

Offshore wind energy storage concept for cost-of-rated-power savings

International Nuclear Information System (INIS)

Qin, Chao; Saunders, Gordon; Loth, Eric

2017-01-01

Highlights: •Investigated CAES + HPT system concept for offshore wind energy; •Validated cost model for offshore wind farm including CAPEX and OPEX items; •Quantified cost-of-rated-power savings associated with CAES + HPT concept; •Estimated savings of 21.6% with CAES + HPT for a sample $2.92 billion project. -- Abstract: The size and number of off-shore wind turbines over the next decade is expected to rapidly increase due to the high wind energy potential and the ability of such farms to provide utility-scale energy. In this future, inexpensive and efficient on-site wind energy storage can be critical to address short-time (hourly) mismatches between wind supply and energy demand. This study investigates a compressed air energy storage (CAES) and hydraulic power transmission (HPT) system concept. To assess cost impact, the NREL Cost and Scaling Model was modified to improve accuracy and robustness for offshore wind farms with large turbines. Special attention was paid to the support structure, installation, electrical interface and connections, land leasing, and operations and maintenance cost items as well as specific increased/reduced costs reductions associated with CAES + HPT systems. This cost model was validated and applied to a sample $2.92 billion project Virginia Offshore case It was found that adaption of CAES + HPT can lead to a substantial savings of 21.6% of this 20-year lifetime cost by dramatically reducing capital and operating cost of the generator and power transmission components. However, there are several additional variables that can impact the off-shore energy policy and planning for this new CAES + HPT concept. Furthermore, these cost-savings are only first-order estimates based on linear mass-cost relationships, and thus detailed engineering and economic analysis are recommended.

Reliability-Based Design and Planning of Inspection and Monitoring of Offshore Wind Turbines

DEFF Research Database (Denmark)

Marquez-Dominguez, Sergio

Maintaining and developing a sustainable wind industry is the main motivation of this PhD thesis entitled “Reliability-based design and planning of inspection and monitoring of offshore wind turbines”. In this thesis, statistical methods and probability theory are important mathematical tools used...... and offshore wind turbine foundations with the aim of improving the design, decreasing structural costs and increasing benefits. Recently, wind energy technology has started to adopt risk and reliability based inspection planning (RBI) as a methodology based on Bayesian decision theories together...

Historical Population Estimates For Several Fish Species At Offshore Oil and Gas Structures in the US Gulf of Mexico

Science.gov (United States)

Gitschlag, G.

2016-02-01

Population estimates were calculated for four fish species occurring at offshore oil and gas structures in water depths of 14-32 m off the Louisiana and upper Texas coasts in the US Gulf of Mexico. From 1993-1999 sampling was conducted at eight offshore platforms in conjunction with explosive salvage of the structures. To estimate fish population size prior to detonation of explosives, a fish mark-recapture study was conducted. Fish were captured on rod and reel using assorted hook sizes. Traps were occasionally used to supplement catches. Fish were tagged below the dorsal fin with plastic t-bar tags using tagging guns. Only fish that were alive and in good condition were released. Recapture sampling was conducted after explosives were detonated during salvage operations. Personnel operating from inflatable boats used dip nets to collect all dead fish that floated to the surface. Divers collected representative samples of dead fish that sank to the sea floor. Data provided estimates for red snapper (Lutjanus campechanus), Atlantic spadefish (Chaetodipterus faber), gray triggerfish (Balistes capriscus), and blue runner (Caranx crysos) at one or more of the eight platforms studied. At seven platforms, population size for red snapper was calculated at 503-1,943 with a 95% CI of 478. Abundance estimates for Atlantic spadefish at three platforms ranged from 1,432-1,782 with a 95% CI of 473. At three platforms, population size of gray triggerfish was 63-129 with a 95% CI of 82. Blue runner abundance at one platform was 558. Unlike the other three species which occur close to the platforms, blue runner range widely and recapture of this species was dependent on fish schools being in close proximity to the platform at the time explosives were detonated. Tag recapture was as high as 73% for red snapper at one structure studied.

Offshore Wind Energy Systems Engineering Curriculum Development

Energy Technology Data Exchange (ETDEWEB)

McGowan, Jon G. [Univ. of Massachusetts, Amherst, MA (United States); Manwell, James F. [Univ. of Massachusetts, Amherst, MA (United States); Lackner, Matthew A. [Univ. of Massachusetts, Amherst, MA (United States)

2012-12-31

Utility-scale electricity produced from offshore wind farms has the potential to contribute significantly to the energy production of the United States. In order for the U.S. to rapidly develop these abundant resources, knowledgeable scientists and engineers with sound understanding of offshore wind energy systems are critical. This report summarizes the development of an upper-level engineering course in "Offshore Wind Energy Systems Engineering." This course is designed to provide students with a comprehensive knowledge of both the technical challenges of offshore wind energy and the practical regulatory, permitting, and planning aspects of developing offshore wind farms in the U.S. This course was offered on a pilot basis in 2011 at the University of Massachusetts and the National Renewable Energy Laboratory (NREL), TU Delft, and GL Garrad Hassan have reviewed its content. As summarized in this report, the course consists of 17 separate topic areas emphasizing appropriate engineering fundamentals as well as development, planning, and regulatory issues. In addition to the course summary, the report gives the details of a public Internet site where references and related course material can be obtained. This course will fill a pressing need for the education and training of the U.S. workforce in this critically important area. Fundamentally, this course will be unique due to two attributes: an emphasis on the engineering and technical aspects of offshore wind energy systems, and a focus on offshore wind energy issues specific to the United States.

Identification of support structure damping of a full scale offshore wind turbine in normal operation

DEFF Research Database (Denmark)

Koukoura, Christina; Natarajan, Anand; Vesth, Allan

2015-01-01

damping from the decaying time series. The Enhanced Frequency Domain Decomposition (EFDD) method was applied to the wind turbine response under ambient excitation, for estimation of the damping in normal operation. The aero-servo-hydro-elastic tool HAWC2 is validated with offshore foundation load...... maxima of an impulse response caused by a boat impact. The result is used in the verification of the non aerodynamic damping in normal operation for low wind speeds. The auto-correlation function technique for damping estimation of a structure under ambient excitation was validated against the identified...... measurements. The model was tuned to the damping values obtained from the boat impact to match the measured loads. Wind turbulence intensity and wave characteristics used in the simulations are based on site measurements. A flexible soil model is included in the analysis. The importance of the correctly...

Offshoring in textile industry

OpenAIRE

MONTÓN GARCÍA, JORGE

2015-01-01

[ EN] This project is about offshoring in the textile industry, focusing in the rights violated in this process, this concept can be defined as the moving of various operations of a company to another country for reasons such as lower labor costs or more favorable economic conditions in that other country. The project describes the evolution of offshoring, which started in 1960’s and has continued since then; it was characterized primarily by the transferring of factories from the develope...

Dispatching capacity in manufacturing facility offshoring

DEFF Research Database (Denmark)

Madsen, Erik Skov; Knudsen, Mette Præst

2010-01-01

This paper investigates how a dispatching capacity of motivation, relational dynamics and structures seen from the sending context influence the entire knowledge transfer process in manufacturing facility offshoring. An inductive and qualitative approach is taken and five main themes are derived...... from the four empirical cases. In the discussion, the five themes i.e. extra tasks, previous experiences, involvement of all groups of employees, teaching skills and organizational support in the dispatching context are linked with a theoretical model leading to the identification of seven testable...

Boundary Spanning in Offshored Information Systems Development Projects

Science.gov (United States)

Krishnan, Poornima

2010-01-01

Recent growth in offshore outsourcing of information systems (IS) services is accompanied by managing the offshore projects successfully. Much of the project failures can be attributed to geographic and organizational boundaries which create differences in culture, language, work patterns, and decision making processes among the offshore project…

Polymorphic microsatellite markers for the endangered fish, the slender shiner Pseudopungtungia tenuicorpa and cross-species amplification across five related species.

Science.gov (United States)

Kim, K S; Moon, S J; Han, S H; Kim, K Y; Bang, I C

2016-09-02

The slender shiner Pseudopungtungia tenuicorpa (Cypriniformes; Cyprinidae; Gobioninae) is an endangered freshwater fish species endemic to Korea. The current strategies for its conservation involve the study of population genetic characters and identification of management units. These strategies require suitable molecular markers to study genetic diversity and genetic structure. Here, we developed nine polymorphic microsatellite markers for P. tenuicorpa for the first time by applying an enrichment method from a size-selected genomic library. The developed microsatellite markers produced a total of 101 alleles (average 11.2). The observed and expected heterozygosities averaged 0.805 and 0.835, respectively. Among the nine identified markers, five markers showed successful amplification across five related Korean Gobioninae species. Thus, the microsatellite markers developed in this study will be useful to establish conservation strategies for both P. tenuicorpa and other related species.

Offshore wind resources at Danish measurement sites

Energy Technology Data Exchange (ETDEWEB)

Barthelmie, R J; Courtney, M S; Lange, B; Nielsen, M; Sempreviva, A M [Risoe National Lab., Dept. of Wind Energy and Atmospheric Physics, Roskilde (Denmark); Svenson, J; Olsen, F [SEAS, Haslev (Denmark); Christensen, T [Elsamprojekt, Fredericia (Denmark)

1999-03-01

In order to characterise wind and turbulence characteristics at prospective offshore wind energy sites, meteorological observations from a number of purpose-built offshore monitoring sites have been analyzed and compared with long wind speed time series. New analyses have been conducted on the data sets focussing on meteorology, turbulence, extreme winds and wind and wave interactions. Relationships between wind speed, turbulence and fetch are highly complex. Minimum turbulence intensity offshore is associated with wind speeds of about 12 m/s. At lower wind speeds, stability effects are important while at higher winds speeds wind and wave interactions appear to dominate. On average, turbulence intensity offshore at 48 m height is approximately 0.08 if no coastal effects are present. However, the effect of the coastal discontinuity persists in wind speed and turbulence characteristics for considerable distances offshore. The majority of the adjustment of appears to occur within 20 km of the coast. (au)

Lake Michigan offshore ecosystem structure and food web changes from 1987 to 2008

Science.gov (United States)

Rogers, Mark W.; Bunnell, David B.; Madenjian, Charles P.; Warner, David M.

2014-01-01

Ecosystems undergo dynamic changes owing to species invasions, fisheries management decisions, landscape modifications, and nutrient inputs. At Lake Michigan, new invaders (e.g., dreissenid mussels (Dreissena spp.), spiny water flea (Bythotrephes longimanus), round goby (Neogobius melanostomus)) have proliferated and altered energy transfer pathways, while nutrient concentrations and stocking rates to support fisheries have changed. We developed an ecosystem model to describe food web structure in 1987 and ran simulations through 2008 to evaluate changes in biomass of functional groups, predator consumption, and effects of recently invading species. Keystone functional groups from 1987 were identified as Mysis, burbot (Lota lota), phytoplankton, alewife (Alosa pseudoharengus), nonpredatory cladocerans, and Chinook salmon (Oncorhynchus tshawytscha). Simulations predicted biomass reductions across all trophic levels and predicted biomasses fit observed trends for most functional groups. The effects of invasive species (e.g., dreissenid grazing) increased across simulation years, but were difficult to disentangle from other changes (e.g., declining offshore nutrient concentrations). In total, our model effectively represented recent changes to the Lake Michigan ecosystem and provides an ecosystem-based tool for exploring future resource management scenarios.

Assessment of weld thickness loss in offshore pipelines using computed radiography and computational modeling

International Nuclear Information System (INIS)

Correa, S.C.A.; Souza, E.M.; Oliveira, D.F.; Silva, A.X.; Lopes, R.T.; Marinho, C.; Camerini, C.S.

2009-01-01

In order to guarantee the structural integrity of oil plants it is crucial to monitor the amount of weld thickness loss in offshore pipelines. However, in spite of its relevance, this parameter is very difficult to determine, due to both the large diameter of most pipes and the complexity of the multi-variable system involved. In this study, a computational modeling based on Monte Carlo MCNPX code is combined with computed radiography to estimate the weld thickness loss in large-diameter offshore pipelines. Results show that computational modeling is a powerful tool to estimate intensity variations in radiographic images generated by weld thickness variations, and it can be combined with computed radiography to assess weld thickness loss in offshore and subsea pipelines.

Offshore Vendors’ Software Development Team Configurations

DEFF Research Database (Denmark)

Chakraborty, Suranjan; Sarker, Saonee; Rai, Sudhanshu

2012-01-01

This research uses configuration theory and data collected from a major IT vendor organization to examine primary configurations of distributed teams in a global off-shoring context. The study indicates that off-shoring vendor organizations typically deploy three different types of configurations...

Preliminary Design of a Multi-Column TLP Foundation for a 5-MW Offshore Wind Turbine

Directory of Open Access Journals (Sweden)

Yanping He

2012-10-01

Full Text Available Currently, floating wind turbines (FWTs may be the more economical and suitable systems with which to exploit offshore wind energy in deep waters. Among the various types of floating foundations for offshore wind farms, a tension leg platform (TLP foundation can provide a relatively stable platform for currently available offshore wind turbines without requiring major modifications. In this study, a new multi-column TLP foundation (WindStar TLP was developed for the NREL 5-MW offshore wind turbine according to site-specific environmental conditions, which are the same as the OC3-Hywind (NREL conditions. The general arrangement, main structure and mooring system were also designed and investigated through hydrodynamic and natural frequency analyses. The complete system avoids resonance through the rotor excitations. An aero-hydro-servo-elastic coupled analysis was carried out in the time domain with the numerical tool FAST. Statistics of the key parameters were obtained and analysed and comparisons to MIT/NREL TLP are made. As a result, the design requirements were shown to be satisfied, and the proposed WindStar TLP was shown to have favourable motion characteristics under extreme wind and wave conditions with a lighter and smaller structure. The new concept holds great potential for further development.

Evaluation of Small-Scale Laterally Loaded Monopiles in Sand

DEFF Research Database (Denmark)

Roesen, Hanne Ravn; Thomassen, Kristina; Sørensen, Søren Peder Hyldal

2011-01-01

In current designs of offshore wind turbines, monopiles are often used as foundation. The behaviour of the monopoles when subjected to lateral loading has not been fully investigated. In this paper the diameter effect on laterally loaded non-slender piles in sand is evaluated by means of results ...

Uniaxial Tension Test of Slender Reinforced Early Age Concrete Members

Directory of Open Access Journals (Sweden)

Wenbo Zhang

2011-08-01

Full Text Available The present study aims to obtain the tensile properties of early age concrete based on a uniaxial tension test employing RC slender members. First, the paper shows that concrete strain is equal to the strain of rebar at the mid-span of the RC member. The tensile Young’s modulus and the strain capacity of early age concrete are estimated using strain measurements. The experiment indicated that the tensile Young’s modulus at an early age is higher than the compressive modulus. This observation was similar to one found in a previous investigation which used a direct tension test of early age concrete. Moreover, the paper describes how an empirical equation for mature concrete can be applied to the relation between uniaxial tensile strength and splitting tensile strength even in early age concrete. Based on a uniaxial tension test, the paper proposes an empirical equation for the relationship between standard bond stresses and relative slip.

46 CFR 15.520 - Mobile offshore drilling units.

Science.gov (United States)

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false Mobile offshore drilling units. 15.520 Section 15.520... REQUIREMENTS Manning Requirements; Inspected Vessels § 15.520 Mobile offshore drilling units. (a) The requirements in this section for mobile offshore drilling units (MODUs) supplement other requirements in this...

Experimental Comparison of Non-Slender Piles under Static Loading and under Cyclic Loading in Sand

DEFF Research Database (Denmark)

Sørensen, Søren Peder Hyldal; Ibsen, Lars Bo

2012-01-01

An experimental evaluation of the pile behavior of non-slender piles exposed to static and cyclic lateral loading is presented. The tests were conducted in a pressure tank at Aalborg University. This enabled the possibility of applying an overburden pressure to the soil. When conducting small......-scale tests at 1-g the determination of the friction angle and the Young’s modulus of elasticity of the soil are difficult and further these soil parameters varies greatly with depth. These uncertainties were avoided by application of an overburden pressure....

EWeA Offshore 2013 - Side event: 'Offshore wind energy - Potentialities and industrial opportunities in France and in Germany. French-German cross perspectives

International Nuclear Information System (INIS)

Genachte, Anne-Benedicte; Kavafyan, Philippe; Wagner, Andreas; Bour, Gregoire

2013-01-01

At the EWEA Offshore 2013 exhibition, the French-German office for Renewable energies (OFAEnR) organised a side-conference on Offshore wind energy and its Potentialities and industrial opportunities in France and in Germany. In the framework of this French-German exchange of experience, about 50 participants exchanged views on the conditions for the development of a durable offshore wind energy industry both in France and in Germany. This document brings together the available presentations (slides) made during this event: 1 - Supporting industrial development of offshore wind in Europe (Anne-Benedicte Genachte); 2 - Offshore wind energy: the Bremerhaven experience. An asset for the deployment of a complete industrial field in France (Philippe Kavafyan); 3 - Status, Prospects and Challenges for Offshore Wind energy in Germany - incl. Legal Framework and Presentation of cost reduction study results (Andreas Wagner); 4 - Offshore grid connection in Germany - Challenges and recommendations (Gregoire Bour)

The EU Offshore Safety Directive and its potential effects. Opportunity or handicap?; Die EU Offshore Safety Directive und ihre moeglichen Auswirkungen. Chance oder Handicap?

Energy Technology Data Exchange (ETDEWEB)

Schwiederowski, Claudia [RWE Dea AG, Hamburg (Germany)

2014-07-01

The purpose of the EU Offshore Safety Directive, which took effect on 18 July 2013, is to define minimum requirements for the prevention of severe accidents in connection with offshore crude oil or natural gas activities of any kind and the containment of the follow-on effects of such accidents. This is without question a logical consequence of the offshore incidents seen around the globe over the past decades. An interesting question in this context is for whom the EU Offshore Safety Directive has become an opportunity and for whom a handicap. [German] Ziel der am 18. Juli 2013 in Kraft getretenen EU Offshore Safety Direktive ist die Festlegung von Mindestanforderungen fuer die Verhinderung schwerer Unfaelle bei Offshore-Erdoel- bzw. - Erdgasaktivitaeten und die Begrenzung etwaiger Unfallfolgen. Nach den weltweiten Offshore- Ereignissen der vergangenen Jahrzehnte ist dies ohne Zweifel eine logische Entwicklung. Nun stellt sich die Frage: Fuer wen entwickelt sich die EU Offshore Safety Directive zur Chance, fuer wen zum Handicap?.

The offshorization of economy: the present realities

Directory of Open Access Journals (Sweden)

Maslak Olga

2017-01-01

Full Text Available In this article the essence and main types of offshore zones have been studied. It has been analyzed the main reasons for cooperation with the tax havens, established that the main reason of the Ukrainian economy offshorization is not only the desire of economic entities to optimize taxes, but also the desire to protect their assets from the negative impact of the crisis phenomena in the national economy during 2010-2016. The foreign experience of the anti-offshore regulation has been researched. It has been defined that the general anti-offshore regulation vector should be based on the principles of financial transparency, active cooperation with the international community, an optimal combination of instruments that restrict the capital outflows and the effective instruments that stimulate the business development in the country. It has been also established that the mechanism of deoffshorization should be aimed not only at elimination of the territories with the preferential taxation, but also at receiving benefits from their use on the basis of the existing financial infrastructure of the leading world offshore centers. The experience of China in attracting additional foreign investments, gaining wider access to financial resources through the cooperation with an offshore financial centre has been researched.

Offshoring and financial markets

Directory of Open Access Journals (Sweden)

Gianfranco Battisti

2014-06-01

Full Text Available The paper analyses the nature and extent of the offshore world, a grey area that is playing a major role in present-day economy. The main institutions moulding this peculiar environment are discussed: preferential tax regimes, tax havens and offshore financial centers. Their role in the globalised world is outlined after a scrutiny of the specialized literature, reports by non-governmental bodies and companies’ advertisings. Finally, we present a tentative reconstruction of its geographical organization, inclusive of cartographic representations of the main international networks.

Vibration of an Offshore Structure Having the Form of a Hollow Column Partially Filled with Multiple Fluids and Immersed in Water

OpenAIRE

Lin, Hsien-Yuan; Lee, Jeng-Nan; Sung, Wen-Hao

2012-01-01

This paper employs the numerical assembly method (NAM) to determine the exact frequency-response amplitudes of an offshore structure such as piles or towers having the form of a hollow column filled with multiple fluids, immersed in water, carrying an eccentric tip mass supported by a translational spring and/or a rotational spring, and subjected to a harmonic force. The hollow column is modeled as a Bernoulli-Euler cantilever beam fixed at the bottom. For the case of zero harmonic force, the...

31 CFR 587.406 - Offshore transactions.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 587.406 Section 587.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... MONTENEGRO) MILOSEVIC SANCTIONS REGULATIONS Interpretations § 587.406 Offshore transactions. The prohibitions...

Screening Criteria and Considerations of Offshore Enhanced Oil Recovery

Directory of Open Access Journals (Sweden)

Pan-Sang Kang

2016-01-01

Full Text Available The application of enhanced oil recovery (EOR in offshore oil fields has received significant attention due to the potentially enormous amount of recoverable oil. However, EOR application offshore is in its very early stage due to conditions that are more complex than onshore oil fields, owing to the unique parameters present offshore. Therefore, successful EOR applications in offshore oil fields require different screening criteria than those for conventional onshore applications. A comprehensive database for onshore applications of EOR processes together with a limited offshore EOR application database are analyzed in this paper, and the important parameters for successful offshore application are incorporated into the new EOR screening criteria. In this paper, screening criteria to determine acceptable EOR processes for offshore fields, including hydrocarbon gas miscible, CO2 miscible, and polymer processes, are presented. Suggested screening criteria for these EOR processes comprise quantitative boundaries and qualitative considerations. Quantitative screening criteria are predominantly based on quantifiable data, such as oil and reservoir properties. Qualitative screening considerations mainly focus on the operational issues present offshore, including platform space constraints, limited disposal options, injectant availability, and flow assurance matters (including hydrate formation and difficulties in emulsion separation.

Frequency-domain characteristics of aerodynamic loads of offshore floating vertical axis wind turbines

DEFF Research Database (Denmark)

Borg, Michael; Collu, M.

2015-01-01

The re-emerging interest in vertical axis wind turbines for floating offshore applications has led to a need to investigate the relatively complex dynamics of such floating offshore structures. Through the use of a coupled model of dynamics this article investigates the frequency......-domain characteristics of floating vertical axis wind turbine aerodynamic loads. The impact of platform induced motion on aerodynamic loads is discussed in detail, with results indicating an increase in aerodynamic loads of several orders of magnitude over the range of frequencies usually containing significant wave...

Energy Usage of Residents on Offshore Islands in Taiwan

Directory of Open Access Journals (Sweden)

Szu-Cheng Lu

2015-05-01

Full Text Available A field study was conducted through interviews on offshore islands in Taiwan to investigate the energy usage of local residents. A comparison of household appliance usage in mainland Taiwan with that on the offshore islands revealed that, overall, the most commonly used household appliances are steam cookers/rice cookers, water dispensers, and washing machines. For other household appliances, Levels 2 and 3 offshore isles have lower use penetration rates compared with those in mainland Taiwan and on Level 1 offshore isles, particularly for the use of computers. By contrast, the use penetration rate for chest freezers on Levels 2 and 3 offshore isles is high, and each household has one or more freezers on average. This appliance is not a commonly observed household product in mainland Taiwan or on Level 1 offshore isles. Furthermore, because of the government policy, every household on parts of Level 2 offshore isles and on all Level 3 offshore isles has a fixed monthly charge of electricity. The transportation of liquefied petroleum gas is also inconvenient, and the gas price is slightly higher, leading to the tendency of residents to consume excessive amounts of electrical energy, which does not correspond with the aim of the government to conserve energy and reduce carbon emissions; thus, the relevant authorities’ review and improvement on energy consumption on Levels 2 and 3 offshore isles are required.

Sensitivity analysis of floating offshore wind farms

International Nuclear Information System (INIS)

Castro-Santos, Laura; Diaz-Casas, Vicente

2015-01-01

Highlights: • Develop a sensitivity analysis of a floating offshore wind farm. • Influence on the life-cycle costs involved in a floating offshore wind farm. • Influence on IRR, NPV, pay-back period, LCOE and cost of power. • Important variables: distance, wind resource, electric tariff, etc. • It helps to investors to take decisions in the future. - Abstract: The future of offshore wind energy will be in deep waters. In this context, the main objective of the present paper is to develop a sensitivity analysis of a floating offshore wind farm. It will show how much the output variables can vary when the input variables are changing. For this purpose two different scenarios will be taken into account: the life-cycle costs involved in a floating offshore wind farm (cost of conception and definition, cost of design and development, cost of manufacturing, cost of installation, cost of exploitation and cost of dismantling) and the most important economic indexes in terms of economic feasibility of a floating offshore wind farm (internal rate of return, net present value, discounted pay-back period, levelized cost of energy and cost of power). Results indicate that the most important variables in economic terms are the number of wind turbines and the distance from farm to shore in the costs’ scenario, and the wind scale parameter and the electric tariff for the economic indexes. This study will help investors to take into account these variables in the development of floating offshore wind farms in the future

Offshore Aquaculture: I Know It When I See It

Directory of Open Access Journals (Sweden)

Halley E. Froehlich

2017-05-01

Full Text Available Offshore aquaculture is increasingly viewed as a mechanism to meet growing protein demand for seafood, while minimizing adverse consequences on the environment and other uses in the oceans. However, despite growing interest in offshore aquaculture, there appears to be no consensus as to what measures commonly define an offshore site or how effects of offshore aquaculture—relative to more nearshore practices—are assessed. This lack of agreement on what constitutes offshore aquaculture has the potential to convolute communication, create uncertainty in regulatory processes, and impede understanding of the ecological implications of offshore farming. To begin addressing these issues, we reviewed and analyzed biologically-focused primary and gray literature (Ntotal = 70 that categorize and quantify characteristics of offshore aquaculture from around the world. We found that many “offshore” descriptions are relatively close to shore (<3 nm and significantly shallower (minimum depth ≤30 m than may be assumed. We also uncovered an overall lack of consistent reporting of even the most common location-focused metrics (distance from shore, depth, current, a dearth of impact related studies (n = 17, and narrow scope of the studies themselves (i.e., 82% nutrient pollution. Of the finite subset of articles that investigated negative ecological impacts of offshore aquaculture, we found the probability of any measurable impact from an offshore farm appears to significantly decrease with distance from the farm (probability of measurable response at 90 m ± SE = 0.01 ± 0.03. Such general, but informative points of reference could be more robustly quantified with better systematic and standardized reporting of physical farm characteristics and a broader scope of ecological investigation into the effects of marine aquaculture. With offshore aquaculture still in its infancy, consistent metrics are needed for a comparable framework to guide sustainable

Canadian East Coast offshore petroleum industry safe lifting practices respecting offshore pedestal cranes, offshore containers, loose gear, other lifting devices, and operational best practices : standard practices

Energy Technology Data Exchange (ETDEWEB)

NONE

2007-11-15

This document was developed by a working group with representatives from the petroleum industry, the Offshore Petroleum Boards and Certifying Authorities. It outlines industry best practices for operators responsible for the management, planning and execution of offshore lifting operations. Its purpose is to assist in the interpretation of applicable legislation and standards. Considered within the practice are safe design requirements, manufacture, certification, testing, maintenance and inspection requirements for pedestal cranes, offshore containers, loose gear and lifting devices. Operational best practices for lifting operations are also included along with a section that identifies additional requirements for personnel lifting operations, including personnel transfers by crane and man-riding operations. 82 refs., 2 tabs., 4 figs., 3 appendices.

31 CFR 544.406 - Offshore transactions.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 544.406 Section 544.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... SANCTIONS REGULATIONS Interpretations § 544.406 Offshore transactions. The prohibitions in § 544.201 on...

31 CFR 593.406 - Offshore transactions.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 593.406 Section 593.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... SANCTIONS REGULATIONS Interpretations § 593.406 Offshore transactions. The prohibitions in § 593.201 on...

31 CFR 541.406 - Offshore transactions.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 541.406 Section 541.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... § 541.406 Offshore transactions. The prohibitions in § 541.201 on transactions involving blocked...

31 CFR 537.406 - Offshore transactions.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 537.406 Section 537.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... § 537.406 Offshore transactions. The prohibitions in § 537.201 on transactions involving blocked...

31 CFR 542.406 - Offshore transactions.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 542.406 Section 542.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... § 542.406 Offshore transactions. The prohibitions in § 542.201 on transactions involving blocked...

Experimental damping assessment of a full scale offshore mono bucket foundation

DEFF Research Database (Denmark)

Gres, Szymon; Fejerskov, Morten; Ibsen, Lars Bo

2016-01-01

This paper quantifies the system damping of a offshore meteorological mast supported by a Mono Bucket foundation based on a long-term experimental campaign. The structure is located at Dogger Bank west, North Sea, and equipped with a measurement system monitoring acceleration, strain, inclination...

Viewing engineering offshoring in a network perspective

DEFF Research Database (Denmark)

Hansen, Zaza Nadja Lee; Zhang, Yufeng; Ahmed-Kristensen, Saeema

2013-01-01

of how to effectively manage engineering offshoring activities in a context of global engineering networks. The main research question, therefore, is: “Can offshoring of engineering tasks be explained and managed using the concept of Global Engineering Networks (GEN)?” Effective approaches to handling...... of large multinational corporations in Denmark were carried out. Data gathering was mainly documentary studies and interviews. The main data analysis approaches were coding (Strauss and Corbin) and pattern-matching (Yin). The dataset was analysed using the GEN framework suggested by Zhang et al. and Zhang...... by extending the GEN framework to address complications within engineering offshoring. This strengthens both academic fields, and will be able to help engineering managers to develop appropriate engineering network configurations for offshore engineering operations....

Managing Hidden Costs of Offshoring

DEFF Research Database (Denmark)

Larsen, Marcus M.; Pedersen, Torben

2014-01-01

This chapter investigates the concept of the ‘hidden costs’ of offshoring, i.e. unexpected offshoring costs exceeding the initially expected costs. Due to the highly undefined nature of these costs, we position our analysis towards the strategic responses of firms’ realisation of hidden costs....... In this regard, we argue that a major response to the hidden costs of offshoring is the identification and utilisation of strategic mechanisms in the organisational design to eventually achieving system integration in a globally dispersed and disaggregated organisation. This is heavily moderated by a learning......-by-doing process, where hidden costs motivate firms and their employees to search for new and better knowledge on how to successfully manage the organisation. We illustrate this thesis based on the case of the LEGO Group....

Efficient promotion of electricity production from offshore wind; Effiziente Foerderung der Stromerzeugung aus Offshore-Wind

Energy Technology Data Exchange (ETDEWEB)

Panzer, Christian; Auer, Hans; Lettner, Georg [Technische Univ. Wien (Austria). Energy Economics Group (EEG)

2014-03-15

Efficient promotion of electricity production from offshore wind stands in dynamic relationship with various influence factors, the most important of which are promotion instruments, topographic givens, regulation of grid connection, and supraregional market integration concepts. Using three case studies from different countries to highlight national differences in the promotion of offshore wind power plants the present analysis points out ways of improving the efficiency of promotion instruments.

Offshore wind potential evaluation and remote sensing imagery; Evaluation du potentiel eolien offshore et imagerie satellitale

Energy Technology Data Exchange (ETDEWEB)

Fichaux, N.

2003-12-15

Offshore wind energy may help to contribute to the respect of the Kyoto objectives by Europe. It is a key issue to struggle against global change. To sit the future offshore wind parks, it is necessary to accurately evaluate the spatial repartition of the wind potential. We demonstrate that the offshore wind potential shall be represented by maps of wind statistics. As remote sensing is a tool for measuring space physical phenomena, we evaluate its potentialities for mapping wind statistics. Space-borne scatterometers enables the obtention of wind statistics, but far from our areas of interest and at low spatial resolution. Synthetic Aperture Radar (SAR) enables the computation of high resolution wind maps over our areas of interest, but are unsuitable to compute wind statistics. We define the mathematical framework of a statistical method. That method enables to take advantage of both scatterometer and SAR to compute maps of wind statistics at high spatial resolution over the areas of interest. It enables remote sensing to be used operationally to map the offshore wind potential. (author)

31 CFR 543.406 - Offshore transactions.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 543.406 Section 543.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... Interpretations § 543.406 Offshore transactions. The prohibitions in § 543.201 on transactions or dealings...

31 CFR 597.406 - Offshore transactions.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 597.406 Section 597.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... REGULATIONS Interpretations § 597.406 Offshore transactions. The prohibitions contained in § 597.201 apply to...

31 CFR 547.406 - Offshore transactions.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 547.406 Section 547.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... REGULATIONS Interpretations § 547.406 Offshore transactions. The prohibitions in § 547.201 on transactions or...

31 CFR 548.406 - Offshore transactions.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 548.406 Section 548.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... § 548.406 Offshore transactions. The prohibitions in § 548.201 on transactions or dealings involving...

31 CFR 546.406 - Offshore transactions.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 546.406 Section 546.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... § 546.406 Offshore transactions. The prohibitions in § 546.201 on transactions or dealings involving...

31 CFR 588.406 - Offshore transactions.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 588.406 Section 588.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... Interpretations § 588.406 Offshore transactions. The prohibitions in § 588.201 on transactions involving blocked...

Offshore Outlook: the European Side Perspectives offshore : le point de vue européen

Directory of Open Access Journals (Sweden)

Delacour J.

2006-11-01

Full Text Available The offshore hydrocarbon potential of Europe was fully revealed during the 1970s by various major discoveries which, after the first oil shock in 1973 and in the light of the high energy consumption in this zone, were a major asset in the new equilibria that would be found between producing and consuming countries. The offshore potential of Europe is concentrated in two zones: the North Sea and the Mediterranean. The North Sea, with the particularly harsh operating conditions, has quickly given rise to what can today be qualified as a new engineering state-of-the-art. At the same time, developments in the Mediterranean have brought a demonstration of entirely original and profitable petroleum achievements. For the future and despite current economic uncertainties, the outlook for European offshore development remain particularly attractive, obviously with regard to oil, but also, and more and more so, from the standpoint of natural gas. Le potentiel offshore en hydrocarbures de l'Europe a été pleinement mis en évidence au cours des années 70 par un certain nombre de grandes découvertes qui constituaient, après le premier choc pétrolier de 1973, compte tenu des fortes consommations d'énergie dans cette zone, un atout majeur dans les nouveaux équilibres qui s'instauraient entre pays producteurs et pays consommateurs. Le potentiel offshore de l'Europe se concentre sur deux zones : la mer du Nord et la Méditerranée. La mer du Nord, avec des conditions d'exploitation particulièrement sévères, a donné rapidement naissance à ce que l'on peut, aujourd'hui, qualifier de nouvel art de l'ingénieur, tandis que les développements en Méditerranée apportaient la démonstration de réalisations pétrolières tout à fait originales et profitables. Pour le futur, et malgré les incertitudes économiques actuelles, les perspectives de développement de l'offshore européen restent particulièrement attractives, au niveau du pétrole �

Baltic 2 offshore wind farm. Challenges and solutions during design and erection of a 288 MW offshore wind power plant; Baltic 2 Offshore Windpark. Herausforderungen und Loesungen waehrend der Design- und Errichtungsphase eines 288 MW Offshore-Windkraftwerks

Energy Technology Data Exchange (ETDEWEB)

Stamatelopoulos, Georg-Nikolaus; Kansy, Stefan [EnBW Energie Baden-Wuerttemberg AG, Stuttgart (Germany); Hannibal, John Michael [Siemens AG, Hamburg (Germany). Wind Power and Renewables Div.; Frettloehr, Bjoern [EnBW Energie Baden-Wuerttemberg AG, Hamburg (Germany). Wind und Maritime Technik

2015-05-01

Offshore wind offers a great potential for reliable power supply with markedly less future costs. However, offshore also means special requirements related to transport and installation at sea. Even if these requirements alone are very stringent, they are not the only ones that apply. Meeting these challenges requires project organisation comparable to other major projects.

Living on the edge: demography of the slender-billed gull in the Western Mediterranean.

Directory of Open Access Journals (Sweden)

Ana Sanz-Aguilar

Full Text Available Small and peripheral populations are typically vulnerable to local extinction processes but important for the metapopulation dynamics of species. The Slender-billed gull (Chroicocephalus genei is a long-lived species breeding in unstable ephemeral coastal habitats. Their Western Mediterranean populations are relatively small and represent the edge of their global geographical distribution. At a local scale, using long-term data (14 years on annual breeding success and capture-resights of marked individuals, we estimated and compared the vital rates and evaluated the connectivity of two Spanish populations (Ebro Delta and Doñana varying in their local environmental conditions. At a metapopulation scale, we analyzed 22 years of data on breeding numbers to predict their future prospects by means of population demographic models. Local survival and breeding success of gulls from the Ebro Delta was lower than those from Doñana, which is likely the result of higher permanent emigration and/or winter mortality in the former. Gulls from the Ebro Delta wintered mostly in Mediterranean areas whereas those from Doñana did so in Atlantic coasts, where food availability is higher. Whereas adult local survival was constant, juvenile local survival showed temporal parallel variations between colonies, probably related to natal dispersal to other breeding colonies. Our results suggested that dispersal was higher at the Ebro Delta and gulls emigrating from their natal colonies settled preferentially in close patches. We found large fluctuations in breeding numbers among local populations probably related to the fact that the Slender-billed gull is a species adapted to unstable and unpredictable habitats with high abilities to disperse between suitable patches depending on environmental stochastic conditions during breeding.

The Organizational Design of Offshoring

DEFF Research Database (Denmark)

Ørberg Jensen, Peter D.; Larsen, Marcus M.; Pedersen, Torben

2013-01-01

Offshoring can be defined as the relocation of organizational tasks and services to foreign locations. At the same time as the scale and scope of offshoring have reached unprecedented levels in recent years, firms have increasingly been exposed to the challenges relating to managing an organizati...... implies an organizational reconfiguration consisting of three stages: disintegration, relocation and reintegration. We discuss the implications of this perspective and outline a research agenda....

Denmark - supplier of competitive offshore wind solutions. Megavind's strategy for offshore wind research, development and demonstration

Energy Technology Data Exchange (ETDEWEB)

2010-12-15

In May 2006, the Danish Government presented a report on promoting environmentally effective technology and established a number of innovative partnerships. The partnerships intend to strengthen public-private cooperation between the state, industry, universities and venture capital to accelerate innovation for a number of green technologies. The partnership for wind energy is called Megavind. Megavind's strategy for offshore wind describes the offshore challenges and suggests research, development and demonstration (RD and D) priorities to enable offshore wind power become to competitive with other energy technologies. The strategy lists key recommendations as well as key thematic priorities and for each of these a number of RD and D priorities. Under each thematic priority references are made to the European Strategic Energy Technology plan (SET-plan), which prioritises offshore wind RD and D in Europe. (LN)

Transverse Oscillations in Slender Ca ii H Fibrils Observed with Sunrise/SuFI

Energy Technology Data Exchange (ETDEWEB)

Jafarzadeh, S. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway); Solanki, S. K.; Gafeira, R.; Noort, M. van; Barthol, P.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; Riethmüller, T. L. [Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany); Rodríguez, J. Blanco [Grupo de Astronomía y Ciencias del Espacio, Universidad de Valencia, E-46980 Paterna, Valencia (Spain); Iniesta, J. C. del Toro; Suárez, D. Orozco [Instituto de Astrofísica de Andalucía (CSIC), Apartado de Correos 3004, E-18080 Granada (Spain); Knölker, M. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Schmidt, W., E-mail: shahin.jafarzadeh@astro.uio.no [Kiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, D-79104 Freiburg (Germany)

2017-03-01

We present observations of transverse oscillations in slender Ca ii H fibrils (SCFs) in the lower solar chromosphere. We use a 1 hr long time series of high- (spatial and temporal-) resolution seeing-free observations in a 1.1 Å wide passband covering the line core of Ca ii H 3969 Å from the second flight of the Sunrise balloon-borne solar observatory. The entire field of view, spanning the polarity inversion line of an active region close to the solar disk center, is covered with bright, thin, and very dynamic fine structures. Our analysis reveals the prevalence of transverse waves in SCFs with median amplitudes and periods on the order of 2.4 ± 0.8 km s{sup −1} and 83 ± 29 s, respectively (with standard deviations given as uncertainties). We find that the transverse waves often propagate along (parts of) the SCFs with median phase speeds of 9 ± 14 km s{sup −1}. While the propagation is only in one direction along the axis in some of the SCFs, propagating waves in both directions, as well as standing waves are also observed. The transverse oscillations are likely Alfvénic and are thought to be representative of magnetohydrodynamic kink waves. The wave propagation suggests that the rapid high-frequency transverse waves, often produced in the lower photosphere, can penetrate into the chromosphere with an estimated energy flux of ≈15 kW m{sup −2}. Characteristics of these waves differ from those reported for other fibrillar structures, which, however, were observed mainly in the upper solar chromosphere.

Floating Offshore Wind in Oregon: Potential for Jobs and Economic Impacts from Two Future Scenarios

Energy Technology Data Exchange (ETDEWEB)

Jimenez, Tony [National Renewable Energy Lab. (NREL), Golden, CO (United States); Keyser, David [National Renewable Energy Lab. (NREL), Golden, CO (United States); Tegen, Suzanne [National Renewable Energy Lab. (NREL), Golden, CO (United States); Speer, Bethany [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2016-05-01

Construction of the first offshore wind power plant in the United States began in 2015, off the coast of Rhode Island, using fixed platform structures that are appropriate for shallow seafloors, like those located off of the East Coast and mid-Atlantic. However, floating platforms, which have yet to be deployed commercially, will likely need to anchor to the deeper seafloor if deployed off of the West Coast. To analyze the employment and economic potential for floating offshore wind along the West Coast, the Bureau of Ocean Energy Management (BOEM) commissioned the National Renewable Energy Laboratory (NREL) to analyze two hypothetical, large-scale deployment scenarios for Oregon: 5,500 megawatts (MW) of offshore wind deployment in Oregon by 2050 (Scenario A), and 2,900 MW of offshore wind by 2050 (Scenario B). These levels of deployment could power approximately 1,600,000 homes (Scenario A) or 870,000 homes (Scenario B). Offshore wind would contribute to economic development in Oregon in the near future, and more substantially in the long term, especially if equipment and labor are sourced from within the state. According to the analysis, over the 2020-2050 period, Oregon floating offshore wind facilities could support 65,000-97,000 job-years and add $6.8 billion-$9.9 billion to the state GDP (Scenario A).

IEA Wind Task 23 Offshore Wind Technology and Deployment. Subtask 1 Experience with Critical Deployment Issues. Final Technical Report

DEFF Research Database (Denmark)

Lemming, Jørgen Kjærgaard

The final report for IEA Wind Task 23, Offshore Wind Energy Technology and Deployment, is made up of two separate reports: Subtask 1: Experience with Critical Deployment Issues and Subtask 2: Offshore Code Comparison Collaborative (OC3). The Subtask 1 report included here provides background...... information and objectives of Task 23. It specifically discusses ecological issues and regulation, electrical system integration and offshore wind, external conditions, and key conclusions for Subtask 1. The Subtask 2 report covers OC3 background information and objectives of the task, OC3 benchmark exercises...... of aero-elastic offshore wind turbine codes, monopile foundation modeling, tripod support structure modeling, and Phase IV results regarding floating wind turbine modeling....

Design optimization of jacket structures for mass production

DEFF Research Database (Denmark)

Sandal, Kasper

This thesis presents models and applications for structural optimization of jacket structures for offshore wind turbines. The motivation is that automatic design procedures can be used to obtain more cost efficient designs, and thus reduce the levelized cost of energy from offshore wind. A struct......This thesis presents models and applications for structural optimization of jacket structures for offshore wind turbines. The motivation is that automatic design procedures can be used to obtain more cost efficient designs, and thus reduce the levelized cost of energy from offshore wind....... A structural finite element model is developed specifically for the analysis and optimization of jacket structures. The model uses Timoshenko beam elements, and assumes thin walled tubular beams and a linear elastic structural response. The finite element model is implemented in a Matlab package called JADOP...... (Jacket Design Optimization), and the static and dynamic structural response is verified with the commercial finite element software Abaqus. A parametric mesh of the offshore wind turbine structure makes it relatively easy to represent various structures from the literature, as well as exploring...

Offshoring in the Semiconductor Industry: Historical Perspectives

OpenAIRE

Brown, Clair; Linden, Greg

2005-01-01

Semiconductor design is a frequently-cited example of the new wave of offshoring and foreign-outsourcing of service sector jobs. It is certainly a concern to U.S. design engineers themselves. In addition to the current wave of white-collar outsourcing, the industry also has a rich experience with offshoring of manufacturing activity. Semiconductor companies were among the first to invest in offshore facilities to manufacture goods for imports back to the U.S. A brief review of these earlie...

The offshorization of economy: the present realities

OpenAIRE

Maslak Olga; Grishko Natalya; Hlazunova Olha; Vorobiova Kateryna

2017-01-01

In this article the essence and main types of offshore zones have been studied. It has been analyzed the main reasons for cooperation with the tax havens, established that the main reason of the Ukrainian economy offshorization is not only the desire of economic entities to optimize taxes, but also the desire to protect their assets from the negative impact of the crisis phenomena in the national economy during 2010-2016. The foreign experience of the anti-offshore regulation has been researc...

Archaeological Handbook for Establishing Offshore Wind Farms in Sweden. Lillgrund Pilot Project

Energy Technology Data Exchange (ETDEWEB)

Bengtsson, Boel [Bohuslaens Museum, Uddevalla (Sweden)

2008-03-15

The purpose of this handbook is to provide a structured guide for contractors interested in establishing offshore wind farms within Swedish territorial waters and its extended economical zone, in relation to Underwater Cultural Heritage (UCH). It is also applicable to UCH in inland waters. Therefore, this handbook seeks to provide information on; - The management structure of underwater/maritime cultural heritage in Sweden, including institutions and units with maritime antiquarian expertise, - The different types of archaeological remains that can be found around the Swedish coast - in offshore, coastal areas and on the foreshore - which can potentially be affected by offshore wind farm projects, - The laws that underwater archaeological remains are subject to - within the National Maritime Boundary as well as within the contiguous and exclusive economical zones - and the necessary archaeological investigations that need to be considered in order to avoid and/or protect the cultural heritage provided by those remains, - Archaeological standards and methods for assessing and evaluating the potential for finding archaeological remains under water, - The steps that need to be to considered during the planning process of establishing offshore wind farms, and how the contractor and archaeologist can work together in order to make the process more cost effective, and - Considerations for the future. Furthermore, this handbook includes a presentation of archaeological finds made during archaeological surveys in connection with the Lillgrund project. The handbook does not make references to any investigations that may be required in relation to land based archaeological sites other than those which are undertaken close to the shoreline (situated on the foreshore), nor does it consider the visual impact sea-based wind farms might have on cultural heritage

Switching overvoltages in offshore wind power grids

DEFF Research Database (Denmark)

Arana Aristi, Ivan

and cables are presented. In Chapter 4 results from time domain measurements and simulations of switching operations in offshore wind power grids are described. Specifically, switching operations on a single wind turbine, the collection grid, the export system and the external grid measured in several real...... offshore wind farms are shown together with simulation results. Switching operations in offshore wind power grids can be simulated with different electromagnetic transient programs. Different programs were used in the project and compared results are included in Chapter 4. Also in Chapter 4 different......Switching transients in wind turbines, the collection grid, the export system and the external grid in offshore wind farms, during normal or abnormal operation, are the most important phenomena when conducting insulation coordination studies. However, the recommended models and methods from...

Deepwater offshore windfarm. Design fabrication and installation study. Final report

Energy Technology Data Exchange (ETDEWEB)

NONE

2004-07-01

This report discusses the plans and benefits of using the Beatrice oil field installation for the development of the offshore Beatrice windfarm in the Moray Firth. The development of an economic support structure for wind turbine generators to allow development of deepwater wind farms was investigated, and the screening of structural designs, and the analysis of fatigue, fabrication and installation considerations is described. Details are given of the recommendation for a further examination of two structural designs as options for the Beatrice windfarm development, the estimated costs, and the results of an environmental review.

Visual disamenities from off-shore wind farms in Denmark

DEFF Research Database (Denmark)

Ladenburg, Jacob; Dubgaard, Alex; Tranberg, Jesper

2006-01-01

Expansion of the off-shore wind power plays a significant role in the energy policies of many EU countries. However, off-shore wind farms create visual disamenities. These disamenities can be reduced by locating wind farms at larger distances from the coast – and accepting higher costs per k......Wh produced. Base on the choices among alternative wind farm outlays, the preferences for reducing visual disamenities of off-shore wind farms were elicited using the Choice Experiment Method. The results show a clear picture; the respondents in three independent samples are willing to pay for mowing future...... off-shore wind farms away from the shore to reduce the wind farms visibility. However, the results also denote that the preferences vary with regards to the experiences with visual disamenities of off-shore wind farms. The respondents Horns Revs sample, where the off-shore wind farm is located...