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GIS-based floating offshore wind turbine installation site selection using fuzzy analytic hierarchy process in northeast Aegean Sea

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BRODOGRADNJA 2024年第2期75卷

作者： Erkurtulmus, Selahattin Alp Pesman, Emre Yalova Univ Altinova Vocat Sch Naval Architecture Program Yalova Turkiye Karadeniz Tech Univ Surmene Fac Marine Sci Naval Architecture & Marine Engn Dept Trabzon Turkiye

The ever-increasing consumption of electrical energy due to increasing requirements arising in parallel with the developing technology forces manufactures and users to seek new and environmentally compatible energy resources. Due to it endless energy potential and continuity, wind energy, which has been used by humanity for various purposes for centuries, continues its journey, which started with windmills that transform one form of mechanical energy into another, with offshore wind energy turbines. In this study, installation site selection, which is the first step for floating offshore wind turbine installation, is carried out. First, a Fuzzy Analytic Hierarchy Process (F-AHP) is applied to obtain the weights of criteria. Transformed alternatives and criteria in a fuzzy decision matrix through triangular fuzzy numbers are used to obtain a database via a Geographic Information System (GIS). Finally, the installation site and study area are determined. This area is located in the Northeast Aegean Sea, between & Ccedil;anakkale and G & ouml;kgeada, 12 km to the northeast of G & ouml;kgeada, and 12 square kilometers. The minimum distance of the area to ship routes is 3000 m, and its minimum distance to fault lines is 2000 m. The average sea depth is 110 m, and the average wind speed is 9.26 m/s (18 knots). With this potential, enough energy can be generated for settlements on G & ouml;kgeada and the coastlines.

关键词： Floating offshore wind turbine Fuzzy Analytic Hierarchy Process (F-AHP) Geographic Information System (GIS) G & ouml kgeada North Aegean Sea

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A critical review of machine learning algorithms in maritime, offshore, and oil & gas corrosion research: A comprehensive analysis of ANN and RF models

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OCEAN ENGINEERING 2024年 295卷

作者： Imran, Md Mahadi Hasan Jamaludin, Shahrizan Ayob, Ahmad Faisal Mohamad Univ Malaysia Terengganu Fac Ocean Engn Technol & Informat Program Maritime Technol & Naval Architecture Kuala Terengganu 21030 Terengganu Malaysia

Corrosion presents significant challenges in the marine, offshore, and oil and gas industries, resulting in annual economic losses amounting to billions of dollars. To address these losses and ensure the structural integrity of marine infrastructure, it is essential to implement effective corrosion monitoring techniques. In recent years, machine learning algorithms have gained prominence across various fields, offering innovative solutions to corrosion-related concerns. This paper provides a comprehensive critical review, primarily focusing on the two most prevalent machine learning algorithms: artificial neural networks and random forests. The review critically analyzes their applications, methodologies, and effectiveness in the realm of marine and offshore steel structures, oil and gas pipelines, as well as construction materials like Al alloys and Mg alloys and the analysis of corrosion coating behavior. Furthermore, this study explores the key findings and inherent limitations of these machine learning techniques, emphasizing their potential in corrosion prediction, detection, and the mitigation of corrosion issues in the marine, offshore, and oil and gas industries. By identifying existing research gaps and offering recommendations for future investigations, this paper emerges as an invaluable resource for researchers, engineers, and practitioners aiming to advance corrosion prevention and management strategies within these pivotal domains.

关键词： Corrosion Artificial neural network Random forest Marine Offshore Oil & gas

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Theory of the cubic autoproduct and its utility for noisy direction of arrival estimation

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JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2024年第3期156卷 1887-1902页

作者： Joslyn, Nicholas J. Dowling, David R. Univ Michigan Appl Phys Program Ann Arbor MI 48109 USA Univ Michigan Dept Naval Architecture & Marine Engn Ann Arbor MI 48109 USA

Autoproducts are quadratic or higher products of frequency-domain acoustic fields that can mimic genuine fields at frequencies within or outside the original field's bandwidth. Past studies have found a variety of interesting autoproduct properties but have been limited to quadratic autoproducts. This paper presents cubic autoproduct theory and documents how noise suppression may be attained with the cubic frequency-difference autoproduct, a product of three frequency-domain acoustic fields. The cubic autoproduct's field equations, developed from the inhomogeneous Helmholtz equation, and analytical results in single- and two-path environments justify interpretating the cubic autoproduct as a pseudofield and underscore its similarities to the quadratic autoproducts. For nonzero field bandwidth, many frequency triplets satisfy the relationship for a single cubic autoproduct frequency. Thus, bandwidth averaging can lead to serendipitous noise suppression and is shown herein to facilitate field-phase-structure recovery from ideal free space fields corrupted by Gaussian noise. Cubic-autoproduct-based direction of arrival (DOA) estimation using signal and noise recordings collected in the ocean are found to be more accurate than conventional DOA estimates from the same data. In particular, cubic autoproduct results showed a 3-5 dB noise suppression advantage for 4- and 6-kHz direct- and reflected-path sounds broadcast 200 m to a four-element receiving array. (C) 2024 Acoustical Society of America.

关键词： Frequency domain analysis

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Coherence of the frequency-difference autoproduct deduced from high-frequency acoustic fields scattered from a rough sea surface

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JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2024年第1期156卷 600-609页

作者： Joslyn, Nicholas J. Dahl, Peter H. Dowling, David R. Univ Michigan Appl Phys Program Ann Arbor MI 48105 USA Univ Washington Appl Phys Lab Seattle WA 98105 USA Univ Michigan Dept Naval Architecture & Marine Engn Ann Arbor MI 48105 USA

The prevalence of random scattering from a rough ocean surface increases with increasing chi = kh cos theta , where k is the acoustic wavenumber, h is the root-mean-square surface height, and theta is the incidence angle. Generally, when chi >> 1, coherence between incident and surface-scattered fields is lost. However, such coherence may be recovered when chi >> 1 by considering the frequency-difference autoproduct of the surface-scattered field, a quadratic product of complex fields at nearby frequencies. Herein, the autoproduct's coherent reflection coefficient for chi > 20 is determined from surface-scattered sound fields obtained from 50 independent realizations of the rough ocean surface measured in pelagic waters off the coast of California in January 1992. The recordings were made with a source at a depth of 147 m that broadcasted 30 and 40 kHz signals to a single receiver 576 m away at depth of 66 m. An analytic formula for the coherent reflection coefficient of the frequency-difference autoproduct, based on the Kirchhoff approximation and a Gaussian surface autocorrelation function, compares favorably with measurements. Improved agreement with the single-receiver measurements is possible via a minor adjustment to the surface autocorrelation length. The adjustment identified here matches that determined previously from horizontal spatial coherence estimates utilizing the experiment's eight-element receiving array.

关键词： Reflection

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Coherent reflection recovery in scattering from the ocean surface using the frequency-difference autoproduct^a)

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JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2024年第3期155卷 1868-1880页

作者： Joslyn, Nicholas J. Dahl, Peter H. Dowling, David R. Univ Michigan Appl Phys Program Ann Arbor MI 48109 USA Univ Washington Appl Phys Lab Seattle WA 98105 USA Univ Michigan Dept Naval Architecture & Marine Engn Ann Arbor MI 48109 USA

The coherence of rough sea-surface-scattered acoustic fields decreases with increasing frequency. The frequency-difference autoproduct, a quadratic product of acoustic fields at nearby frequencies, mimics a genuine field at the difference frequency. In rough-surface scattering, the autoproduct's lower effective frequency decreases the apparent surface roughness, restoring coherent reflection. Herein, the recovery of coherent reflection in sea surface scattering via the frequency-difference autoproduct is examined for data collected off the coast of New Jersey during the Shallow Water '06 (SW06) experiment. An acoustic source at depth 40 m and receiver at depth 24.3 m and range 200 m interrogated 160 independent realizations of the ocean surface. The root mean square surface height h was 0.167 m, and broadcast frequencies were 14-20 kHz, so that 2.5 <= k h cos theta <= 3.7 for acoustic wavenumber k and incidence angle theta. Measured autoproducts, constructed from scattered constituent fields, show significant coherent reflection at sufficiently low difference frequencies. Theoretical results, using the Kirchhoff approximation and a non-analytic surface autocorrelation function, agree with experimental findings. The match is improved using a numerical strategy, exploiting the relationship between autoproduct-based coherence recovery, the ocean-surface autocorrelation function, and the ocean-surface height spectrum. Error bars computed from Monte Carlo scattering simulations support the validity of the measured coherence recovery. (c) 2024 Acoustical Society of America.

关键词： Surface roughness

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Aero-Hydrodynamic Coupled Dynamic Characteristics of Semi-Submersible Floating Offshore Wind Turbines Under Inflow Turbulence

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China Ocean Engineering 2023年第4期37卷 660-672页

作者： JIANG Hai-rui BAI Xing-lan Murilo A.VAZ School of Naval Architecture and Maritime Zhejiang Ocean UniversityZhoushan 316022China Key Laboratory of Offshore Engineering Technology of Zhejiang Province Zhoushan 316022China Ocean Engineering Program Federal University of Rio de JaneiroRio de JaneiroBrazil

In this study,the frequency characteristics of the turbulent wind and the effects of wind-wave coupling on the low-and high-frequency responses of semi-submersible floating offshore wind turbines(FOWT)are *** wave load components,such as first-order wave loads,combined first-and second-order difference-frequency wave loads,combined first-and second-order sum-frequency wave loads,and first-and complete second-order wave loads are taken into consideration,while different turbulent environments are considered in aerodynamic *** com-parison is based on time histories and frequency spectra of platform motions and structural load responses and statistical *** findings indicate that the second-order difference-frequency wave loads will significantly increase the natural frequency of low-frequency motion in the responses of the platform motion and structure load of the semi-submersible platform,which will cause structural fatigue *** the action of turbulent wind,the influences of second-order wave loads on the platform motion and structural load response cannot be ignored,especially under extreme sea ***,in order to evaluate the dynamic responses of semi-submersible FOWT more accurately,the actual environment should be simulated more realistically.

关键词： turbulence characteristics floating offshore wind turbines second-order hydrodynamic loads low-and high-frequency responses aero-hydrodynamic coupling

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Extensive design and aerodynamic performance investigation of diffuser augmented wind turbine (DAWT) guided by generalized actuator disc theory

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RENEWABLE & SUSTAINABLE ENERGY REVIEWS 2024年 192卷

作者： Dogru, Safak Yilmaz, Oktay Yildiz Tech Univ Sch Sci & Engn Naval Architecture & Marine Engn Program Yildiz Campus TR-34349 Istanbul Turkiye Numesys Adv Engn Inc Mer AveAtasehir TR-34779 Istanbul Turkiye Yildiz Tech Univ Fac Naval Architecture & Maritime Marine Engn Dept Yildiz Campus TR-34349 Istanbul Turkiye Yildiz Tech Univ Fac Naval Architecture & Maritime Marine Engn Dept Yildiz CampusBlock T1st FloorBesiktas TR-34349 Istanbul Turkiye Turkiyenin Otomobili Giris im Grubu San ve T AS TO TR-41400 Gebze Kocaeli Turkiye

Shrouding a turbine boosts power, lowers cut-in speed, but raises installation costs, and limits adaptability to wind shifts. A compact, wide-angle DAWT with competitive capacity is crucial for practical installations. Small turbines, often in fluctuating wind sites, necessitate thorough off-design performance analysis. A relatively short, wide-angle GOE431 diffuser is optimized by an efficient response surface method. Inverse blade element method, combined with actuator disc DAWT CFD considering wake swirl, shapes 90 cm-diameter rotor blade with minimal iterations. Implications of Generalized Actuator Disc Theory on DAWT design and performance are addressed with three-dimensional CFD for the first time. This approach unveiled substantial room for improving DAWT efficiency and uncovered key factors causing deviations from ideal performance. Tip leakage and diffuser losses constituted 9.5% of overall energy losses, with wake rotation, blade efficiency, and blade drag at 9.2%. Tip-hub losses, finite blade number, rotor-diffuser interaction, suboptimal rotor, and turbulence contributed to 12.1% in three-bladed DAWT, reaching CP,max = 0.746, with tip losses about one-third of bare turbine. Six-bladed DAWT raised CP by 93%, from 0.417 to 0.805, achieving 75% of ideal DAWT. Finite blade number led to reduced attack angles, higher tip losses, and limited flow expansion, contributing significantly to energy losses. As blade number and design tip-speed-ratio increased, blade Reynolds number decreased, suggesting an optimal combination to minimize energy losses. At off-design, a strong connection existed between thrust coefficient, diffuser efficiency, and Cp increase in wide-angle diffuser DAWTs. Maintaining CT near CT,opt (0.786) at high tip-speedratio led to significant Cp rise.

关键词： Computational fluid dynamics Inverse blade element method Response surface method Finite blade number Thrust coefficient Off-design performance

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Floating buoy fatigue analysis for barge-to-ship operations

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OCEAN ENGINEERING 2023年第1期278卷

作者： Cabral, Weverton Lameira, Pedro Araujo, Andre Fed Univ Para Postgrad Program Marine Engn & Naval Architecture Belem Brazil

Transshipment operations around the world are in high demand, notably so in the Amazon. Usually, this type of operation occurs with mooring buoys. In Brazil, transshipment operations are handled with temporary use contracts of a maximum of 4 years. An adaptation of a method for fatigue analysis of this type of structure is proposed. This method uses computational modeling and simulation via the FEM, focusing on the points of greatest cyclical loading of the padeye, to estimate the useful life of this structural component through S-N curves and internationally recognized regulations. Thereunto, the main tensions in the buoy are obtained from the application of calculated forces for traction on a mooring cable at the bitt of the buoy, whose magnitudes satisfy ranges validated by means of instrumentation on board. The limitations of the method are based on environmental conditions corresponding to a river region with no tidal influence, a fact that allows simplification regarding the influence of waves. The results indicate that regular loads acting on the padeye can ensure a useful life as if the component were a medium-term anchored system since the minimum fatigue life for an applied load of 30 tf is 7.66 years.

关键词： Structural analysis Fatigue Finite element method Mooring buoy Transshipment

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Probabilistic Risk Framework for Nuclear- and Fossil-Powered Vessels: Analyzing Casualty Event Severity and Sub-Causes

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JOURNAL OF MARINE SCIENCE AND ENGINEERING 2025年第3期13卷 553-553页

作者： Tanyildizi-Kokkulunk, Handan Kokkulunk, Gorkem Settles, John Altinbas Univ Vocat Sch Hlth Serv Radiotherapy Program Bakirkoy Campus TR-34145 Istanbul Turkiye Yildiz Tech Univ Naval Architecture & Maritime Fac Marine Engn Dept TR-34349 Istanbul Turkiye Maine Maritime Acad Harold Alfond Sch Engn Engn Dept Castine Campus Castine ME 04420 USA

Maritime activities pose significant safety risks, particularly with the growing presence of nuclear-powered vessels (NPVs) alongside traditional fossil-powered vessels (FPVs). This study employs a probabilistic risk assessment (PRA) approach to evaluate and compare accident hazards involving NPVs and FPVs. By analyzing historical data from 1960 to 2024, this study identifies risk patterns, accident frequency (probability), and severity levels. The methodology focuses on incidents such as marine incidents, marine casualties, and very serious cases with sub-causes. Key findings reveal that Russia exhibits the highest risk for very serious incidents involving both NPVs and FPVs, with a significant 100% risk for NPVs. China has the highest FPV risk, while France and the USA show above-average risks, particularly for marine casualties and very serious incidents. Moreover, collision is the most significant global risk, with a 26% risk for NPVs and 34% for FPVs, followed by fire hazards, which also pose a major concern, with a 17% risk for NPVs and 16% for FPVs, highlighting the need for enhanced safety and fire-prevention measures. In conclusion, comparative analysis highlights the need for enhanced stability improvements, fire prevention, and maintenance practices, particularly in the UK, France, Russia, and China. This study underscores the importance of targeted safety measures to mitigate risks, improve ship design, and promote safer maritime operations for both nuclear- and fossil-fueled vessels.

关键词： nuclear-powered fossil-powered vessels maritime accident PRA

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STUDY ON ROBUST DESIGN FOR NAVIGATION DYNAMICS TEST FOR SMALL CATAMARAN 42

STUDY ON ROBUST DESIGN FOR NAVIGATION DYNAMICS TEST FOR SMAL...

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ASME 42nd International Conference on Ocean, Offshore and Arctic Engineering (OMAE)

作者： Lin, Chun-Cheng Liang, Wei-Li Natl Def Univ Dept Power Vehicle & Syst Engn CCIT Taoyuan City Taiwan Natl Def Univ Master Program Naval Architecture & Ocean Engn CCIT Taoyuan City Taiwan

ISBN: (纸本)9780791886830

With the trend of science and technology development, unmanned autonomous guidance and navigation requirements are critical. Recently, the advanced worldwide countries have been developing unmanned surface vessels (USVs) as well as possible;they applied these USVs to investigate the marine science, surveillance, transportation, and other civilian fields. Its advantages, including saving human resources, reducing the operation risks, increasing the flexibility and efficiency of mission execution. In this study, application a small catamaran with Global Position System (GPS), Lidar, PID controller and two-thrusters, etc. Through series of experiments and analyses were carried out using Taguchi's experimental design methods, Taguchi orthogonal array (L9), ANOVA, and obtained the optimal factor-level combination and approached robust design. Based on the previous study results of resistance and payload for the catamaran, this study selected two control factors: the width of the catamaran (factor-A), and thruster positions (factor-B). The study results presented that Taguchi's optimal configuration design in manual remote mode and waypoint navigation model is A2B1, and the accuracy is also A2B1 in 85% confidence level. The impact of accuracy is analyzed using Taguchi's experimental design method, which is expected to improve unmanned surface vessels' tracking and navigation accuracy and be applied by relevant research agencies.

关键词： unmanned surface vessels catamaran Lidar Taguchi orthogonal array waypoint navigation

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