bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Method for Identifying Compatible Locations for Wave Energy Exploration With Different WECs
Authors: Ramos Sara , Gonçalves Marta , Guedes Soares Carlos 
Published: October 2021

Abstract
This paper aims to assess the marine space availability for the nearshore and offshore wave energy exploration while avoiding conflict with any technical, environmental, legal or other use restriction. Within the available areas retrieved in a GIS environment, it is presented a method to evaluate the performance of various state-of-the-art Wave Energy Converter technologies in terms of the expected Power Output Capacity Factor and Capture Width, when potentially working in the characteristic sea states found on the selected areas. The method is applied to a case study in the Archipelago of Azores. The data of the wave resource utilized comes from a hindcast model refined down to a spatial resolution of 0.05° that makes possible the detailed analysis and spatial comparison of results at insular local scales. The results intend to provide stakeholders and decision-makers with meaningful information about the suitable locations for the wave energy exploration and about the most efficient converter devices in such locations for the potential deployment of a wave energy exploration facility.
Coupled Time-Domain Hydro-Elastic Simulation for Submerged Floating Tunnel Under Wave Excitations
Authors: Jin Chungkuk , Kim Sung-Jae , Kim MooHyun 
Published: October 2021

Abstract
We develop a fully-coupled time-domain hydro-elasticity model for the Submerged Floating Tunnel (SFT) based on the Discrete-Module-Beam (DMB) method. Frequency-domain simulation based on 3D potential theory results in multibody’s hydrodynamic coefficients and excitation forces for tunnel sections. Subsequently, we build the time-domain model with the multibody Cummins equation and external stiffness matrix from the Euler-Bernoulli and Saint-Venant torsion theories. We establish the mooring line model with rod theory and couple components with translational springs at their respective connection locations. We then compare the dynamic motions, wave forces, and mooring tensions between the present and Morison-equation-based elastic models under regular wave excitations at different submergence depths. The present model is especially important for the shallowly submerged tunnel in which the Morison model shows exaggerated motions, especially at high-frequency range.
Prediction of the Financial Losses of Subsea Pipeline Failure
Authors: Aljaroudi Alireda A. 
Published: October 2021

Abstract
The consequences of subsea crude pipeline failure drastically affect the continuity of oil supply and the ability of operating companies to meet market demand. Moreover, it reduces clients’ confidence and reliance on operating companies. There are mainly two types of failures that severely affect the integrity and operability of a pipeline. These are the leakage caused by gradual thinning of the pipeline due to corrosion and the leakage caused by a rupture pressure. The first form of failure results in a constant slow leakage that go over time without being noticed. While the second form of failure takes place without warning which makes the restoration effort extremely difficult and time consuming. Both forms of failure result in delayed production, environmental damage, legal claims as well as financial losses that operating companies could incur. Moreover, leaked oil products adversely impact other industries which bring these industries into a halt. Such industries may include fishery, maritime transportation, and tourism industries. This paper presents a method for predicting the financial losses that a company could incur in the event a corroded pipeline undergoes the abovementioned failures. Basically, this method can be used as a standard estimating tool for predicting the financial losses if such events occur.
Early Engagement of ECA in Offshore Deepwater Pipeline Design
Authors: Zhou Daowu , Cao Lingjun , Sriskandarajah T. , Lewis Mark , Manso Daniel 
Published: October 2021

Abstract
Welding acceptance criteria derived through ECA is typically performed after the detailed design. The design loads, together with pipeline and girth weld material testing data, are inputs to ECA and used to evaluate the pipeline girth weld integrity for determining the criticality of potential weld flaws.
With ever increasing challenging environment (deepwater, HP/HT, aggressive fluid composition etc) in the oil and gas field, the fatigue damage and fracture failure may become a serious concern, consequently limiting the productivity of the pipeline fabrication. It is therefore essential to integrate ECA into the design loop to remove the uncertainty and risk to achieve a practically workable fabrication solution.
In this paper, a strategy to integrate early ECA into pipeline detailed design phase is presented. A case study in a deepwater subsea channel crossing demonstrates that an early ECA engagement effectively mitigates the significant fatigue and fracture risk and obtains workable welding acceptance criteria for fabrication.
Drift Motion of Floating Bodies Under the Action of Green Water
Authors: Tavakoli Sasan , Huang Luofeng , Babanin Alexander V. 
Published: October 2021

Abstract
Numerical simulations are peformed to model the dynamic motions of a free floating body exposed to water waves. The solid body has low freeboard and draft, and its upper deck can be washed by the steep waves. Thus, the green water phenomenon occurs as large waves interact with the floating body. The aim of the research is to improve the understanding of the green water emerging above the upper deck of a floating plate. A thin floating body with barriers is also modeled. For the case of the body equipped with barriers, no green water occurs. Green water has been seen to affect the wave field and the dynamic motions of the plate. It is observed that when water can wash the upper surface of the floating object, drift speed is slightly decreased as a proportion of the energy of waves is dissipated above the body. Water waves are seen to impact the upper surface of the thin floating body as the green water flows over its upper deck. Furthermore, water is seen to impact the plate as its front edge re-enters the water. The first water impact only occurs when the floating body is not equipped with any barrier. By sampling the numerical simulations, it is observed that the non-dimensional value of the impact pressure, resulting from the green water, is larger for the case of smaller wavelength.
Flow Field Inside and Around a Square Fish Cage Considering Fish School Swimming Pattern
Authors: Dong Shuchuang , Park Sang-gyu , Zhou Jinxin , Li Qiao , Yoshida Takero , Kitazawa Daisuke 
Published: October 2021

Abstract
The interaction between fluid and fish cage with stocked fish is extremely complex, including fluid and structure, as well as fluid and fish swimming behavior. The on-current swimming pattern of fish schools was found toward the incoming flow in the previous laboratory studies, which is different from the circular swimming pattern commonly observed in the farming site. In this study, a pseudo fish school structure model (PFS) was proposed to reproduce the five circular swimming patterns of farmed yellowtail, and to investigate the influence of fish school behaviors on the flow field inside and around a model square fish cage in laboratory experiments.
The results showed that the drag force acting on the square fish cage increased with the increase of the current speed for all fish school swimming patterns, but no clear difference was observed between the fish school swimming behavior patterns. Overall, the drag force of the square fish cage considering the farmed fish behavior decreased by 11.8%, compared to the drag force of the fish cage without PFS. The current speeds inside and downstream of the fish cage increased almost linearly with increasing current velocities. Compared with the case of the fish cage without PFS, the current speed inside the cage under motionless closely PFS (C0), revolving closely PFS (CR), motionless loosely PFS (L0) and revolving loosely PFS (LR) conditions changed by 10.8%, 9.4%, 65.8% and 39.7%, respectively. In addition, compared to the case of the fish cage without PFS, the current speeds under C0, CR, L0 and LR conditions decreased by 89.8%, 16.3%, 58.2%, and 31.9%, respectively, at 16.0cm downstream from the fish cage, and decreased by 69.2%, 19.4%, 62.7% and 26.3%, respectively, at 63.6cm downstream from the fish cage. Furthermore, the current speed distribution and relative horizontal turbulence intensity distribution inside and around the fish cage under different fish school swimming pattern was discussed. In the future, we will use live fish to conduct experiments to evaluate fish school models.
What Is Tsunami Earthquake?
Authors: Ebisuzaki Toshikazu 
Published: October 2021

Abstract
A tsunami earthquake is defined as an earthquake which induces abnormally strong tsunami waves compared with its seismic magnitude (Kanamori 1972; Kanamori and Anderson 1975; Tanioka and Seno 2001). We investigate the possibility that the surface waves (Rayleigh, Love, and tsunami waves) in tsunami earthquakes are amplified by secondly submarine landslides, induced by the liquefaction of the sea floor due to the strong vibrations of the earthquakes. As pointed by Kanamori (2004), tsunami earthquakes are significantly stronger in longer waves than 100 s and low in radiation efficiencies of seismic waves by one or two order of magnitudes. These natures are in favor of a significant contribution of landslides. The landslides can generate seismic waves with longer period with lower efficiency than the tectonic fault motions (Kanamori et al 1980; Eissler and Kanamori 1987; Hasegawa and Kanamori 1987). We further investigate the distribution of the tsunami earthquakes and found that most of their epicenters are located at the steep slopes in the landward side of the trenches or around volcanic islands, where the soft sediments layers from the landmass are nearly critical against slope failures. This distribution suggests that the secondly landslides may contribute to the tsunami earthquakes. In the present paper, we will investigate the rapture processes determined by the inversion analysis of seismic surface waves of tsunami earthquakes can be explained by massive landslides, simultaneously triggered by earthquakes in the tsunami earthquakes which took place near the trenches.
Pipe-in-Pipe Thermal Management System With Adjustable U-Value During Field Life
Authors: Jamieson Harvey , Stanning Alex , Legge Matthew , Sathananthan Ratnam 
Published: October 2021

Abstract
This paper details a new flowline thermal performance control system in which the overall heat transfer coefficient (U-value) of a pipe-in-pipe system can be varied. Large scale physical testing was carried out as part of the technology qualification to verify the system and design models developed. The solution is ideally suited for the increasing numbers of High Pressure High Temperature (HPHT) field developments being made; where the fluid temperature, pressure and flowrates will change significantly over the field life. It allows a new approach to flowline thermal design and operation to be taken for various types of field development.
A qualification program has been performed with independent verification body assessment of the work and results and confirms the predicted performance. This paper describes the qualification method to DNVGL-RP-A203 and associated Technology Readiness Level (TRL) assessment of the components.
The physical design of the system is presented along with examples of how benefits can be realised through its use.
A Study on the Main Parameters That Affects the Reliability of Fatigue Failure in a Marine Drilling Riser
Authors: das Chagas Bruno Luiz Barbosa , Kazuyuki Morooka Celso 
Published: October 2021

Abstract
Advances in subsea exploration in the oceans to discover new petroleum reservoirs and sometimes different kind of minerals at the seabed in ultra deepwater, continuously introduce new challenges in offshore drilling operations. This motivates the development of increasingly safe maritime operations.
In offshore petroleum, a marine drilling riser is the pipe that connects a wellhead at the sea bottom to a drillship at the sea surface, as an access to the wellbore. It serves as a guide for the drilling column with the drill bit and conductor to carry cuttings of rock coming from the wellbore drilling and its construction. Drilling riser is constantly exposed to adversity from the environment, such as waves, sea currents and platform motions induced by waves. These elements of the environment are prevailing factors that can cause a riser failure during deepwater drilling operations with undesirable consequences for the environment.
In the present work, key parameters that influence the probability of fatigue failure in a marine drilling riser are identified, and a parametric evaluation with those parameters are carried out. Dynamic behavior of a riser is previously calculated and fatigue damage is estimated. Afterwards, the First Order Reliability Method (FORM) is applied to determine the probability of fatigue failure on the riser. Fundamentals of the procedure are described, and results are illustrated through the analysis for a typical riser in deepwater drilling operation. Parametric evaluations are done observing points considered as critical along the riser length, and looking to the sensitivity of key parameters in the process. For this study, the SN curve from API guidelines is applied and accumulated fatigue damage is estimated from simulations of the stress time series and applying the Palmgren-Miner’s rule. Finally, the influence of each parameter in the reliability of fatigue failure is verified and discussions given.
Experimental Research on Vibration Characteristics of Laminated Composite Cantilever Beam
Authors: Yang Rui , Li Xiaobin , Li Hongxi 
Published: October 2021

Abstract
In this paper, the vibration characteristics of laminated composite cantilever beam is taken as the research object. Firstly, a vibration formula specific for laminated composite cantilever beam is derived, from which the low order natural frequency of laminated composite cantilever beam is calculated; Secondly, two experimental methods, electrical and optical measurement, are used to study the vibration characteristics of laminated composite cantilever beam, and the influence of different test methods, sensor types, number of measuring points and excitation methods on the test results are analyzed. Through the combination of theory and experiment, a test method that can be applied to the vibration test of composite material laminated structure cantilever beam is obtained. Based on the laser vibration measurement method in the optical method, the results show that the deviation between the experimental data and the theoretical solution is the smallest when the distance between the probe and the specimen is 0.5m and the sampling time is 5s by using the optical fiber vibrometer. The research content of this article can provide a reasonable reference for related vibration test research.
Full Scale Axial, Bending and Torsion Stiffness Tests of a Three Core HVAC Submarine Cable
Authors: Delizisis Panagiotis , Dolianitis Ioannis , Chatzipetros Dimitrios , Kanas Vasileios , Georgallis Georgios , Tastavridis Konstantinos , Stamelos Antonios , Angelis Efstratios 
Published: October 2021

Abstract
Submarine, export cables behave, to some point, as long, flexible cylindrical bodies. Their mechanical performance is crucial during laying and operating processes, which depends to a large extent on their stiffness. Although theoretical methods, used to estimate cable stiffness, are currently available, it is difficult to account for the various physical mechanisms involved, such as internal friction, residual torsion and ‘relaxation’ effects. These mechanisms are expected to affect cable stiffness and should be included some way. To represent more realistically cable stiffness, full-scale tests are performed in this paper. The deviation between theoretical and experimental values appears to be significant in certain cases: hence, non-realistic values for cable stiffness would occur if the stiffness estimation relied only on the theoretical methods. Interesting results, affording an in more depth insight and allowing for a better understanding of the cable mechanical performance, are presented in this paper.
Individual Blade Pitch Control for Alleviation of Vibratory Loads on Floating Offshore Wind Turbines
Authors: Pustina Luca , Pasquali Claudio , Serafini Jacopo , Lugni Claudio , Gennaretti Massimo 
Published: October 2021

Abstract
Among the renewable energy technologies, offshore wind energy is expected to provide a significant contribution for the achievement of the European Renewable Energy (RE) targets for the next future. In this framework, the increase of generated power combined with the alleviation of vibratory loads achieved by application of suitable advanced control systems can lead to a beneficial LCOE (Levelized Cost Of Energy) reduction. This paper defines a control strategy for increasing floating offshore wind turbine lifetime through the reduction of vibratory blade and hub loads. To this purpose a Proportional-Integral (PI) controller based on measured blade-root bending moment feedback provides the blade cyclic pitch to be actuated. The proportional and integral gain matrices are determined by an optimization procedure whose objective is the alleviation of the vibratory loads due to a wind distributed linearly on the rotor disc. This control synthesis process relies on a linear, state-space, reduced-order model of the floating offshore wind turbine derived from aero-hydroelastic simulations provided by the open-source tool OpenFAST. In addition to the validation of the proposed controller, the numerical investigation based on OpenFAST predictions examines also the corresponding control effort, influence on platform dynamics and expected blade lifetime extension. The outcomes show that, as a by-product of the alleviation of the vibratory out-of-plane bending moment at the blade root, significant reductions of both cumulative blade lifetime damage and sway and roll platform motion are achieved, as well. The maximum required control power is less than 1% of the generated power.
Predicting Wind Loads on the Topside of a Self-Propelled Wind Turbine Installation Jack-Up Using CFD
Authors: Sulaiman Zana 
Published: October 2021

Abstract
This paper presents the results of wind load computational fluid dynamics (CFD) calculations performed on the topside structures of a self-propelled wind turbine installation jack-up. The CFD calculations were performed for the jack-up topside structures with and without the deck load. An atmospheric boundary layer profile was applied for the model-scale calculations. The full range of heading angles was considered. The CFD results were validated through comparison with the wind tunnel tests which were carried out at the German-Dutch wind tunnels (DNW) in Marknesse, The Netherlands. Moreover, a comparison is presented between the applied boundary layer profiles throughout the CFD computational domain with those profiles measured in the wind tunnel. The CFD results were found to be in good agreement with the wind tunnel tests for the considered cases, verifying the feasibility of the CFD method as an important design tool for the prediction of wind loads during the design processes of these types of jack-ups.
Managing Pipeline Integrity and Dynamic Free Spans on Mobile Seabed in the Southern North Sea
Authors: Sequeiros Octavio , Ang Sze Yu , Clavin Craig , Upton Jon , Ho Cliff , van der Werf Auke 
Published: October 2021

Abstract
This paper describes the continuous improvement efforts to manage the integrity status of the Southern North Sea subsea pipeline system in the context of free spanning. The dynamic free-spanning threat is typically attributed to a mobile seabed. Current and wave action are constantly moving and eroding sediment by means of sand wave migration and scouring. It can lead to a fluctuation in span characteristics with respect to span length, span height and location over time. It makes pipeline integrity demonstration and spans remediation challenges. Focus areas include (1) identifying regions where operational pipelines are susceptible to critical span formation (2) understanding the broader context of seabed mobility, supported by several years of multibeam echo sound and met ocean data (3) risk-ranking & criticality of span formation (4) developing simplified calculation tool that allows fatigue damage to be estimated and accumulated for every location along the pipeline, conservatively (5) optimising and incorporating risk/event-based survey requirements (6) identification of suitable remediation solutions and developing a decision flow chart to facilitate selection of fit for purpose remediation solutions, with respect to span configuration and the surrounding seabed features. The outcome has improved the robustness of span management, reduced “reactive” span remediation activities, and allowed application of sound technical theory to allocate pipeline traffic light integrity status regarding the observed free spans.
Cementing Irregular Horizontal Wellbores
Authors: Renteria Alondra , Sarmadi Parisa , Frigaard Ian 
Published: October 2021

Abstract
In this work, we study the effect of borehole irregularities during primary cementing of a horizontal section of well. We use a simplified 2D gap-averaged model to compute the displacement of a drilling mud by a spacer within an elliptical annulus that represents an oval irregularity. We also present a series of 3D numerical simulations using a Volume of Fluid method to capture the interface between the fluids. The 3D model allows us to study the effects of more local irregularities such as wall roughness that can be imported from a caliper log.
The dynamics of the displacement of two fluids in a horizontal uniform circular annulus is governed by buoyancy, eccentricity and the rheology of the fluids. A positive density difference combined with a slow mean pumping speed promotes slumping of the second fluid towards the bottom of the annulus. Nevertheless, high eccentricity values (e = 1-standoff) are common due to the weight of the casing pulling downwards, opposing the buoyancy force. Finally, the rheology of the fluids is relevant to determine the presence of un-displaced layers of mud, e.g. at the walls.
The same competition described above holds true in the elliptical annulus. Results from the 2D gap-averaged model suggest that the elliptical shape incorporates an additional way of altering the velocity field around it. The effect is more evident when orienting the largest radius of the elliptical annulus at different angles. Results from 3D simulations show that the interface follows irregularities and the local roughness can improve the displacement by inducing secondary flows. However, enlargements result in poor displacement.