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Abstract: Abstract This paper investigates the factors influencing innovation adoption in ports by conducting a systematic literature review and proposes a comprehensive framework for understanding the process of innovation adoption. The maritime sector is a typical example of a business-to-business market, whereas the information technology industry is an example of a business-to-consumer market. We show that factors for innovation adoption applicable to a business-to-consumer market are also relevant to a business-to-business market. The factors that were found relate to the adopting port’s characteristics and include know-how, organization support, organizational structure, financial capacity, a port’s network embeddedness, and risk-taking. Furthermore, they concern the characteristics of the innovation such as the costs, relative advantage, complexity, compatibility, trialability, and observability. Finally, stakeholder pressures were identified relating to the customer, competitive port, regulatory bodies, and society. PubDate: 2024-08-21
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Abstract: Abstract This study presents a detailed analysis of weather window accessibility for marine renewable energy (MRE) sites along Ireland's coast, utilizing a robust 12 year met-ocean dataset. The research focuses on key test sites—the atlantic marine energy test site (AMETS), the galway bay test site (GBTS), and the Westwave Demonstration Site—and expands to a broader spatial analysis of Irish coastal waters. By integrating significant wave height and wind data, the study evaluates site accessibility, emphasizing the paramount role of wave height in determining access. Findings reveal substantial spatial variability in accessibility, with high-resource areas like AMETS facing greater access challenges due to harsher conditions, as opposed to the more accessible GBTS. The study underscores the need for a nuanced, region-specific approach to MRE development in Ireland, highlighting how strategic planning and technological advancements are crucial in exploiting the country's significant MRE potential. The results also stress the importance of long-term data for accurate environmental variability assessment, offering vital insights for future MRE site viability and strategy development. PubDate: 2024-08-21
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Abstract: Abstract Characteristics of the wind waves measured in the coastal waters of the northeastern Bay of Bengal are examined for 4 years. A comparison of the energy wave period (Te) with different wave periods shows that the average wave period (Tm–1,1), significant wave period (T1/3), and integral period (Ti) are closer to Te. A maximum wave height of 5.5 m is observed, and the most typical values for the wave period range between 4 and 6.5 s. The steepness of the highest wave is 0.058. In the coastal waters, the values of the peak wave period (Tp) indicate a swell dominance in the monsoon. Short-period waves (Tp < 6 s) are relatively higher in 2015 and the long-period waves (Tp > 8 s) in 2013 and the changes are due to the variations in monsoon. A large number of long-period waves is observed during the northeast monsoon. Thirty-seven freak wave events occurred, and the presence of freak waves is higher in the monsoon. Interannual variations in the mean of Tavg are up to 5% and that of the 90-percentile of the average wavelength (λTavg) is up to 10%. The annual mean wave power is 5 kW/m and annually during 25% of the time, the wave power is more than 7 kW/m. PubDate: 2024-08-01
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Abstract: Abstract Seven detached breakwaters were built at a depth of 3–4 m between 1998 and 2003 to provide a safe area for swimming and recreational activities in El Nakheel beach west of Alexandria on The Egyptian Northern Coast. The purpose of this research is to investigate the velocity, pattern, and direction of sea currents, and study the hazard rate (HR) of swimming at various water depths due to sea current velocity, in addition to verifying the relation between these currents and the number of sinking accidents in the vicinity of the study area. The generated currents by existing pattern of the seven detached breakwaters were simulated by the numerical model Delft-3D. Four scenarios of detached breakwaters were studied. These scenarios included changing in the structural design of the existing breakwaters, such as reducing some of gaps or adding new breakwaters or transferring them to different depths. The generated currents in scenario (1), which suggested using emerged breakwaters to fully close some gaps between detached breakwaters by 50%, had the lowest velocity (0.25 m/s) with minimum circulation and rip pattern and their direction was mostly parallel to the shoreline. The hazard rate (HR) of swimming at a depth of 1.50 m in this scenario was 1.125 m2/sec and it is a suitable rate for most swimming age groups. PubDate: 2024-08-01
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Abstract: Abstract Floating offshore wind (FOW) requires cost reduction to compete with fixed offshore wind, and other traditional and renewable energy sources. One major cost contributor in FOW is the mooring system. Volume effects are expected to deliver significant savings for most cost drivers, but moorings are already produced at scale and at volume for the oil and gas sector, and innovation is required to address the specific challenges of FOW. This paper investigates the use of Dublin Offshore’s load reduction device (LRD) integrated with high-modulus synthetic mooring lines in an inclined taut mooring (ITM) configuration for semi-submersible station keeping. The ITM comprises a 3-line array with vertically loaded anchors within a reduced mooring footprint, fully synthetic Dyneema® DM20 mooring lines, and optimized system compliance provided through an in-line LRD on each mooring line. The ITM allows mooring designers to significantly reduce component count, risk of failure, CAPEX, and lifetime cost of the mooring system. Wave tank testing was carried out at 1:60 scale using a variant of the TetraSub, a market-ready 15 MW semi-submersible FOW platform, developed by Stiesdal Offshore Technologies (SOT) at the Offshore Basin in MARIN in Q3 2021. The experimental results of wave tank testing presented in this paper demonstrate the feasibility of the innovative ITM mooring configuration. In addition, good agreement is observed between LRD quasi-static performance and each of the numerical analysis in OrcaFlex, and the wave tank testing results. PubDate: 2024-08-01
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Abstract: Abstract In this work, a multi-robot system maneuvers floating objects through the so-called caging strategy, where the target objects are non-self-propelled and have different shapes and inertia. To achieve this, a swarm of non-holonomic autonomous surface vehicles acts as pusher-boat caging and pushing objects of various shapes without relying on specific information about their shape, inertia, or initial orientation. Then, the floating object is maneuvered to a desired position and orientation. Numerical simulations use a nonlinear maneuvering model for all the bodies, while cooperative object transportation uses a homogeneous multi-robot system with direct communication and decentralized control. Tasks use target, repulsion, propulsion, and object transportation algorithms. The navigation of the swarmed object uses a proportional integral derivative (PID) controller and waypoint navigation. Finally, the researchers carried out numerical simulations to evaluate the performance and verify the proposed strategy. The results show that during the object transportation, the different-shaped objects were successfully caged, handled, and transported, demonstrating the robustness of this approach was successful in all cases following the proposed rules. In addition, simulations showed the effectiveness of the proposed method, demonstrating transportation without the use of any extra mechanism, only through contact forces. PubDate: 2024-08-01
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Abstract: Abstract Resistance reduction is one of the main goals in designing high-speed vessels to achieve higher speeds. The wetted surface caused by water spray is one of the main parts of the hydrodynamic resistance in high-speed vessels. In this research, the geometrical characteristics of the spray rail, including the underlying angle, width, and number of spray rails were changed to evaluate their effects on the hydrodynamic behavior of the vessel using computational fluid dynamics (CFD). Validation of the numerical simulation has been done with the performed tests in the NIMALA towing tank. The Taguchi method is used to optimize the geometry of the spray rail by specifying 18 different models each of them containing two modes (the the direction of chine and parallel with keel) to be simulated according to its design of experiment method. The results show that the underlying angle and the number of spray rails have a direct relationship with the increase in the Froude number of the vessel. Also the width of the spray rail has an inverse relationship with the increase in the Froude number. Also, it has been found that the spray rails parallel to the keel have a more constructive effect on hydrodynamic performance and longitudinal stability of the vessel compared to the spray rails in the direction of the chine. PubDate: 2024-07-20
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Abstract: Abstract Understanding and exploring the dynamics of underwater explosions (UNDEX) is of paramount importance in defense, marine engineering, and underwater research due to their potential to inflict severe damage on structures, submarines, and marine life. The following study conducts a detailed examination of the shockwave and bubble dynamics of underwater explosion (UNDEX) in case of increasing hydrostatic pressure, explosive mass, and varying boundary conditions such as the presence of seabed and the ocean surface. A numerical method based upon Riemann problem and Godunov’s scheme is utilized in this study of underwater explosions to predict the shockwave, bubble pulsation including pulsation time, pulsation pressure and bubble expansion and contraction. The numerical method was benchmarked against the published experimental results. Over 96% of accuracy was achieved when comparing the numerical results with the experiment. Finally, a detailed study was conducted to understand the explosion phenomenon for varying charge masses and depth in both shallow water as well as in deep-sea near seabed. The utilized numerical technique proved to be a great method to study the underwater explosion for damage prediction, structural integrity, and the severity of the explosion. PubDate: 2024-07-16
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Abstract: Abstract A submerged, neutrally buoyant cylinder may be an attractive option for a wave energy converter design due to its potential for highly efficient energy capture, advantageous power scaling relative to its length, and potential to weather storms by submerging to safer depths. Additionally, it serves as an ideal testbed to better understand heave and surge forcing interactions on wave energy systems. Understanding the hydrodynamic interactions between the cylinder and incoming waves can lead to better modeling and control design and in turn more efficient energy absorption. This paper presents the design, implementation, and experimental results of a submerged cylinder wave energy experimental testbed made using a two degree of freedom gantry (T-bot) in surge and heave controlled by coupled motors that are programmed to apply desired forces on the cylinder. We demonstrate the efficacy of the approach by applying forces to emulate mechanical springs and dampers with user specified spring and damping coefficients. System identification of the gantry is used to produce a feedback controller that counteracts the gantry friction in addition to applying the virtual spring and damping forces. Experiments in a 116 m wave tank with waves of amplitude up to 31.75 mm and periods between 1 s and 2.5 s show agreement with linear model predictions, experiments with a passive spring oscillator system, and WEC-Sim simulations. The results provide the groundwork for future rapid prototyping of advanced control designs and further study of the near-cylinder hydrodynamic interactions that drive energy absorption of wave energy converters. PubDate: 2024-07-15
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Abstract: Abstract This paper envisages the use of the receding horizon concept to deal with the path following control problem of marine vehicles, deployed in cooperative mode. In this way, the system comprises a Lyapunov-based model predictive control to guide the vehicle along the desired path, and a moving horizon estimator to provide noise attenuated estimates of the states required by the control. It also comprises a consensus-based cooperative controller to solve the collective formation control problem. The performance of the whole system is assessed through numerical simulation, considering three vehicles operating in cooperative mode along a 2D path. The results exhibit the efficacy of both controllers, evidencing the quality of the outputs supplied by the estimator. PubDate: 2024-06-28
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Abstract: Abstract In the context of the energy transition, the Campos Basin region is one of the most important and strategic areas in Brazil, given its relevance in oil and gas production, great wind resources, and proximity to the most populous region in the country. In this context the performance of a Numerical Weather Prediction (NWP) operational system based on the Weather Research and Forecasting model was evaluated, in addition to an investigation of the influence of physiographic aspects and meteorological systems on the near-surface wind regime. The numerical results of wind were evaluated in comparison to 1 year of observational data at onshore and offshore meteorological stations. Despite the well-known spin-up problem of NWP models, the best results were obtained in the first 24 h. Consequently, the spin-up was less significant for model performance than the deviation from the initial conditions. Overall, the best results were obtained for the offshore rather than onshore region. The model was more assertive for the most frequent wind speed classes and had a worse performance for the extreme classes, overestimating the weakest winds and underestimating the strongest winds. A counterclockwise directional bias was also found overall, indicating overestimation (underestimation) of synoptic (local) forcing. From a seasonal perspective, the best results were obtained for the winter period, characterized by the greater influence of the South Atlantic Subtropical Anticyclone. The onshore winds revealed a pattern of clockwise rotation as one moves towards higher latitudes. One hypothesis is that this pattern is a consequence of the synergistic influence of orography, coastline shape, land-sea drag difference, and air-sea interaction phenomena. Finally, this study indicates that the NWP system is promising, proving to be an important tool for managing activities related to the current oil and gas industry in addition to subsidizing the expansion of wind energy exploration. PubDate: 2024-06-17 DOI: 10.1007/s40722-024-00332-2
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Abstract: Abstract Enterprises in increasing numbers allocate substantial expenses to offshore wind energy development as a pivotal component of the global energy transition from fossil fuels, hence the importance of ensuring the reliability of offshore wind technology becomes ever more significant. At the same time, operation and maintenance (O&M) of offshore wind farms are progressively focusing on the integration of artificial intelligence (AI) for enhancing the efficiency and performance of the wind energy facilities. Decision support strategies based on failure predictions are an important element in this trend. As a result, AI is more frequently used to create time-to-failure predictions based on large amount of data collected from sensors deployed to wind turbines. Nevertheless, unsupervised components or subsystems may occasionally lead to failures. This paper demonstrates a practical application of AI for predicting failures in unsupervised components. Specifically, we focus on a single component: the yaw brakes of a 3 MW wind turbine. The study analyses how the brake pads of these yaw brakes wear out over time, using the data collected from turbine controllers. To predict when these failures are likely to occur, we employ Long-Short-Term Memory (LSTM) which is empowered by a pre-processed dataset using Support Vector Machine (SVM) for clustering of the relevant data. This combination of SVM and LSTM presents an alternative approach to enhancing predictive maintenance strategies, which can improve the operational reliability and cost-efficiency of offshore wind energy systems. PubDate: 2024-06-16 DOI: 10.1007/s40722-024-00335-z
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Abstract: Abstract When a submerged body moves in a near-surface water environment, forces and moments act on the liquid, which can have a significant impact on the nature of its movement. It is obvious that the shape of the hull influences the hydrodynamic characteristics of the submerged body. In the given paper, we considered the motion of bodies with different cross-sectional shapes at small depths. The fields of hydrodynamic pressures arising around bodies when moving with different relative velocities were obtained using numerical simulation. The dependency of the wave resistance RW on models with specified parameters was determined. We established the nature of the change in the values of the lift force FZ and the trimming moment MY for different Froude numbers. With the help of a cable towing system installed in the ice tank, models of submerged bodies were towed. For the first time, the dependencies of the relative vertical displacement of models arising under the influence of the lift force were experimentally obtained, and the trim angles were determined. The relationship between numerical simulation data and experimental results was shown. It was concluded that the values of the studied parameters depend on the prismatic coefficient of the models and the completeness coefficient of the midsection frame. PubDate: 2024-06-13 DOI: 10.1007/s40722-024-00333-1
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Abstract: Abstract Using wave energy for desalination has recently gained attention from researchers and authorities. This technique, known as “wave to water,” is particularly crucial for regions and islands that have access to seas and oceans but suffer from a shortage of drinking water. Both industrial devices and academic studies were developed to explore this concept. However, further research is needed to optimize the geometry of these devices. Optimizing the geometry of a wave energy converter (WEC) through field studies can be expensive. Therefore, investigations are divided into numerical and experimental studies, in which the former requires validation through observed data. In this paper, a preliminary experimental study is conducted to examine parameters influencing the performance of a paddle-type WEC. The study investigates factors such as paddle width, water depth, coast slope, and wave frequency period by conducting laboratory tests. Paddle-type WECs are commonly used in industry. The results of the analysis are discussed in detail, along with consideration for scaling up these findings. PubDate: 2024-06-03 DOI: 10.1007/s40722-024-00331-3
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Abstract: Abstract In recent years, marine energy research, like many other branches of science and engineering, has explored the use of increasingly advanced machine learning techniques. Data-driven and machine learning techniques have been shown to be particularly useful in investigating the complex fluid–structure interactions between electromechanical and hydraulic systems and ocean waves. This work provides a comprehensive review of studies that have implemented machine learning and data-driven approaches for system modeling, developing control algorithms, optimizing the system using data-driven modeling, forecasting power generation, and conducting modeling and optimization of arrays of wave energy converters (WECs). The paper briefly discusses various wave energy conversion approaches along with the machine learning techniques typically used in wave energy research. The literature is divided into three main areas: WEC modeling, modeling of WEC arrays, and works focused on forecasting wave characteristics to evaluate the performance of WECs. Finally, the paper discusses the prospective research and development of data-driven and machine learning techniques in this field. The review encompasses literature published between 2008 and 2022. PubDate: 2024-05-30 DOI: 10.1007/s40722-024-00330-4
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Abstract: Abstract The current study identifies the critical design considerations for the universal joint of a cutter suction dredger. The cutter suction dredger is modelled as a hybrid two subsystems consisting of hardware-in-the-loop (HIL) and Software-in-the-loop (SIL). HIL, consisting of Dredge hull, spud and soil embedment, is modelled experimentally. System identification is carried out, and a single degree of freedom (SDOF) system is determined for HIL. The identified dynamic parameters are interfaced with the SIL. SIL consisting of the cutter shaft is modelled numerically. The primary and secondary shaft of the cutter shaft is coupled using springs to emulate the universal joint. A sensitivity analysis of the acceleration amplification based on the spud location relative to the hull is carried out. It is observed that the spud position relative to the hull has less influence on the acceleration amplification. A soft universal joint produces a higher response transmitted to the Dredge hull. Further, the influence of the universal joint on the fatigue life of the shaft is analyzed. The results from the fatigue analysis indicate that higher coupling stiffness reduces the fatigue life of the cutter shaft. Therefore, while designing the universal joint, both the impulsive and the fatigue loading must be considered. PubDate: 2024-05-24 DOI: 10.1007/s40722-024-00327-z
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Abstract: Abstract In flume experiments, turbulent flow characteristics around horizontal pipes were investigated in four different arrangements: single pipe, two pipes with a spacing of 0.5D, two pipes with a spacing of D, and three pipes with a spacing of 0.5D. The flow velocity around the pipes at close distances was measured using an Acoustic Doppler Velocimeter (ADV), and turbulent flow parameters, such as Reynolds stresses, turbulence intensity, and the turbulence indicator (I), were calculated. The variations of these parameters with the scour depth underneath the pipes were also examined for each arrangement. The results indicate that the number of pipelines greatly controls the flow domain. In the wake region of the single pipe, there is a higher increase in Reynolds stresses, momentum transfer, turbulent flow, and vortices intensity compared to the other arrangements, leading to a greater scour depth in this case (0.52D). In the arrangement with two pipes at a spacing of D, there is a significant increase in Reynolds stresses in the spacing between the pipes, and counter-rotating vortices in this region cause a greater scour depth (0.41D) compared to the arrangement with 0.5D pipe spacing (0.37D). In addition, the lowest scour depth, as well as the least increase in Reynolds stresses and turbulent flow intensity, was observed in the three-pipe case when the pipe spacing was 0.5D. The maximum I values for experiments 1–4 in the wake region and between the pipes are I ≈ 0.48, I ≈ 0.34, I ≈ 0.38, and I ≈ 0.36, respectively. This shows that the turbulence level in these regions can be classified as moderate. PubDate: 2024-05-21 DOI: 10.1007/s40722-024-00329-x
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Abstract: Abstract To maximise the availability of power extraction from a tidal stream site, tidal turbines need to be able to operate reliably when located within arrays. This requires a thorough understanding of the operating conditions, which include turbulence, velocity shear due to bed proximity and roughness, ocean waves and due to upstream turbine wakes, over the range of flow speeds that contribute to the loading experienced by the devices. High-fidelity models such as Large Eddy Simulation (LES) can be used to represent these complex flow conditions and turbine device models can be embedded to predict loading. However, to inform micro-siting of multiple turbines with an array, the computational cost of performing multiple simulations of this type is impractical. Unsteady onset conditions can be generated from the LES to be used in an offline coupling fashion as input to lower-fidelity load prediction models to enable computationally efficient array design. In this study, an in-house Blade Element Momentum (BEM) method is assessed for prediction of the unsteady loads on the turbines of a floating tidal device with unsteady inflow developed with the in-house LES solver DOFAS. Load predictions are compared to those obtained using the same unsteady inflow to the commercial tool Tidal Bladed and from an Actuator Line Model (ALM) embedded in the LES solver. Estimates of fatigue loads differ by up to 3% for mean thrust and 11% for blade root bending moment for a turbine subject to a turbulent channel flow. When subjected to more complex flows typical of a turbine wake, the predictions of rotor thrust fatigue differ by up to 10%, with loads reduced by the inclusion of a pitch controller. PubDate: 2024-05-08 DOI: 10.1007/s40722-024-00328-y
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Abstract: Abstract The Persian Gulf as one of the regions with a large number of gas and oil reservoirs hosts a considerable number of fixed offshore platforms. Corrosion and fatigue are among the main reasons for damages to these structures. Despite the importance of these structures, little is known about their fatigue reliability in this region. In this paper, we use a scaled-prototype to verify a finite element model used for the reliability assessment of this structure. Historical wave height and period data as well as data from corrosion measurements performed in this region are used to model the fatigue reliability of this platform. Fatigue reliability of this structure is assessed by first-order reliability method results of which are verified by Monte Carlo and importance sampling methods. We studied the effect of corrosion, wave height, and depth of water in the Persian Gulf on the fatigue reliability of this structure. Reliability assessment is carried out in different locations for different ages of the structure. PubDate: 2024-02-01 DOI: 10.1007/s40722-023-00311-z