bluuebunny/crossref_metadata_2025_split huggingface dataset:
LIDAR-Assisted Feedforward Pitch Control of 15 MW Floating Offshore Wind Turbines
Authors: Russell Andrew , Collu Maurizio , McDonald Alasdair , Thies Philipp , Mortimer Alan , Quayle Alexander 
Published: September 2023

Abstract
Nacelle-mounted, forward-facing Light Detection and Ranging (LIDAR) technology is able to measure the wind field as it approaches a wind turbine. Knowledge of the incoming wind can be used for feedforward turbine control, enabling torque, pitch or yaw systems in advance of the wind’s impact. This can enhance turbine performance through improved rotor speed regulation and power capture, while reducing structural loads. LIDAR has previously exhibited its most significant benefits for turbine performance when assisting with blade pitch control in above-rated wind speed conditions. The impact of feedforward pitch control implementation in floating offshore wind turbines is expected to vary for different substructures due to their differing natural frequencies of motion and rates of feedback pitch control actuation, as a consequence of modified controller gains required to overcome negative damping. This computational study outlines the LIDAR-assisted feedforward pitch control implementation approach, and compares its impacts on two floating substructures supporting the IEA 15 MW reference turbine: the UMaine VolturnUS-S Semi-Submersible and the WindCrete Spar. Under turbulent wind conditions and by using a LIDAR simulator to capture the incoming wind field, both floating turbine configurations benefitted from LIDAR-assisted feedforward pitch control, through improved rotor speed regulation by up to 33%, reduced loads by up to 17% and platform motions by up to 19%. These performance improvements can lead to reduced component failure rates, maintenance, and, ultimately, reduced lifetime operations and maintenance expenditure.
Using CFD to Assess the Wind Loads on the Topside of a Self-Propelled Wind Turbine Installation Jack-Up – A Comparative Study of Simplified With Detailed Topside Structures at Model-Scale and Full-Scale
Authors: Sulaiman Zana 
Published: September 2023

Abstract
This paper presents the results of wind loads computational fluid dynamics (CFD) calculations performed on the topside structures of a typical GustoMSC designed self-propelled wind turbine installation jack-up. To investigate the effect of geometrical simplifications on the overall wind loads acting on the jack-up, the CFD calculations were performed for the detailed as well as simplified topside structures. An atmospheric boundary layer profile was applied. 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 simplified and detailed topside structures at model-scale as well as at full-scale. Based on the results of the CFD calculations at model-scale and full-scale, this paper discusses the scale effects of the wind loads acting on a self-propelled wind turbine installation jack-up. Furthermore, the effects of topside simplifications on the wind loads and advantages of the applied approach are highlighted.
Experimental Quantification of Collapse Enhancement From Light Thermal Treatment
Authors: Timms Chris , DeGeer Duane , Chandler Bruce , Liu Ping , Swanek Doug , Chen Qishi 
Published: September 2023

Abstract
Over thirty years ago, as conventional oil and gas prospects began migrating into ultra-deepwater, new engineering, construction, and installation challenges arose, demanding robust solutions to ensure reliable project delivery. Many of these deepwater developments required large-diameter export pipelines, or long-distance transmission lines, with sufficient wall thickness to resist unprecedentedly high external pressures. Pipeline design standards at the time had little or no history of successful ultra-deepwater pipeline design, and questions were raised as to the adequacy of the collapse equations (and lack of supporting collapse test results) for such water depths, as well as the manufacturing limitations associated with the UOE and JCOE linepipe required for these large-diameter pipelines. Innovative solutions were needed.
In the 1990s, C-FER Technologies (1999) Inc. (“C-FER”) and Intecsea Inc. (“Intecsea”) pioneered the development of design methodologies aimed at optimizing pipeline wall thickness design and incorporating collapse enhancement techniques into the successful delivery of ultra-deepwater pipeline projects around the world. Quantifying the strength recovery gained from a light thermal treatment (LTT) process, such as that obtained from a fusion bonded epoxy (FBE) or three-layer coating process, has been the focal point of these techniques. The methods developed at the time have produced, time and again on various projects, highly reliable wall thickness designs, and leading pipeline-design standards have permitted such methods, establishing their acceptance in pipeline wall thickness design.
This paper presents a summary of some of the leading engineering work achieved over approximately thirty years and some of the projects that have implemented these innovative design techniques, including the challenging tests successfully performed, the design results achieved, and the benefits realized.
Surface Corrosion Fatigue Crack Growth Test in Accelerating Environment Where General Surface Corrosion Proceed in Parallel
Authors: Hayashibara Hitoshi , Fueki Ryutaro , Yamamoto Norio , Sugimoto Tomohiro , Ando Takahiro , Tsumura Shuichi , Anai Yosuke , Murakami Chikahisa , Niwa Toshio , Iwata Toshiaki , Ishibashi Kinya 
Published: September 2023

Abstract
Corrosion fatigue behavior in dilute sulfuric acid solution was examined with high tensile steel. Crack growth tests were conducted to obtain the parameters in Paris law while specimens with a semi elliptical slit were immersed in solution to evaluate the change of crack size during no cyclic load condition. The immersion test revealed that a simulated crack depth was shortened in the test solution due to the difference of corrosion rate between a slit tip and a surface, meaning crack depth will actually decrease under the specific low stress range (or no cyclic load) condition where the competitive phenomenon become significant. Quantitative parameters from these tests were included in the crack growth analysis to improve the previous calculated results. Surface crack growth behavior was also examined in the same corrosive environment by using the tensile specimen with a semi-elliptical pre crack. Two different loading conditions were employed to evaluate the competitive phenomenon. Some test was carried out in a continuous cyclic loading, others were conducted in a combination of continuous cyclic load and no load (applied stress was maintained as zero). It was observed that the crack growth was suppressed in low stress range and high surface corrosion rate conditions.
Offloading Operability of Near-Shore FLNG With Side-by-Side Moored LNG Carrier in Shallow Water Depth
Authors: Kim Mun Sung , Lim Jae Hwan , Yuck Rae Hyoung , Kim Hyun Joe , Heo Jae Kyung 
Published: September 2023

Abstract
Recently, the FLNG projects have been developed for the LNG production near shore field with shallow water depth. In this field, FLNG is permanently moored by jetty system or special structures such as Yoke mooring for the liquefaction of feed gas by pipeline in land side. Like FLNGs which operated in deep water, ship-to-ship (STS) offloading operation is considered in near shore FLNG for the transfer of LNG cargo to shuttle LNG carrier through marine loading arm (MLA) with side-by-side (SBS) mooring arrangement.
However, unlike FLNGs which operated in deep water depth, near shore FLNG has relatively short length due to the use of electric and accommodation from the land side. Also, the environmental conditions are quite differing in near shore as well as finite water depth. This meaning that the need of the special consideration of near shore FLNG for side-by-side (SBS) mooring arrangement.
In this paper, a numerical motion analysis for the side-by-side moored FLNG and LNG carrier in near shore field is carried out in frequency-domain and time-domain. In order to assess the offloading operability of near shore FLNG during operation, dynamic loads acting on the mooring lines and fenders as well as relative motion are calculated for several SBS mooring arrangements.
Throughout the study, it is found that the important of numerical accuracy of hydrodynamic analysis in shallow water depth and environmental conditions such as wind, wave and current. Also, the offloading operability is affected by the side-by-side mooring arrangement.
Development of Ice-Load Algorithm for Real-Time Feedback During Simulator Training
Authors: Miller Logan P. , Quinton Bruce , Soper Jonathan , Veitch Brian 
Published: September 2023

Abstract
The use of simulator training for ice navigation is becoming increasingly widespread, in part due to the difficulty, risk, and expense of providing training on vessels in ice-covered waters. Simulator training offers the opportunity for comparatively inexpensive and low risk training for novices in ice-covered conditions. For effective ship operation, it is important to use a vessel to its capacity in ice, without exceeding this capacity and causing damage to the structure. To this end, an algorithm was developed that detects ship-ice collisions, calculates the ice-loads on the structure, and provides the operator with feedback in terms of how close the load is to exceeding the safe capacity of the structure. At present, the algorithm is ship specific in that its development uses finite element analysis for a specific ship to assess the ship’s structural response for a given ice thickness, strength, and contact geometry, to determine the maximum energy at which a safe collision can occur. This safe collision energy limit can then be implemented into simulator training to give real-time feedback to participants about the safety of ship-ice collisions as they occur. An experimental campaign to test the effect of the feedback for simulator training, as well as its utility as an aid onboard the bridge of ships, is proposed.
Experimental Investigation of Annular Displacement With Fluids of Different Density
Authors: Lund Bjørnar , Ytrehus Jan David , Taghipour Ali , Saasen Arild 
Published: September 2023

Abstract
High inclination and horizontal well sections are common in modern well construction. In mature areas like the North Sea region, practically all producers or injector wells will have highly deviated sections. Adequate displacement during the cementing operation is important to ensure annular barrier integrity and zonal isolation of wells. Since all wells must be permanently plugged before abandonment, annular barriers should be made with a long-term perspective and not only to minimize construction time and cost. Controlled laboratory environments with various fluid compositions and flow parameters are important to develop, validate and improve models and practices, both for cementing and other fluid displacement operations such as casing cleaning.
In this paper we present results from laboratory experiments in a 10 meters long test section using water-based model fluids at horizontal and highly deviated angles. The wellbore and casing are represented by 6.5” ID and 5” OD transparent pipes, respectively.
Water and viscosified water, respectively, were displaced by a potassium formate brine (1.3–1.4 sg) at low and high flow rates, without and with string rotation and with concentric and partially eccentric inner pipe (casing). The displacement was monitored using conductivity probes and video camera recordings. The results show that the density difference between the displaced and displacing fluid totally dominates the displacement process. Thus, neither inclination, string rotation, eccentricity or wellbore inclination were found to have significant impact on the displacement process.
Cuttings-Bed Erosion in Horizontal Wells: Biopolymers Impact and its Rheological Dependence
Authors: Pedrosa Camilo , Baynabaj Mohsen , Paso Kristofer , Saasen Arild 
Published: September 2023

Abstract
Efficient wellbore cleaning in highly deviated and horizontal wells is a challenge, as there are large areas where the cuttings tend to be deposited. Insufficient wellbore cleaning could cause major operational problems and vastly increase drilling costs.
Effective removal of the deposited cuttings-bed is mainly driven by flow rate, flow rheology and drill-pipe rotation, nevertheless in cases where it’s not possible to have drill-pipe rotation the challenge should be accomplished by tailoring the fluid rheology to achieve turbulent flow within the maximum flow rate possible. As a common practice water-based drilling fluids are formulated with biopolymers as viscosity modifiers, such as xanthan gum and polyanionic cellulose (PAC) to adjust the drilling fluid rheology. The viscosity profile that each of these biopolymers imparts is very different, as xanthan gum produces a shear-thinning effect, the PAC behaves as a Newtonian fluid.
This paper shows how the different flow behavior of the fluids composed of biopolymers can influence the cuttings-bed erosion, in a bench-scale lab setup without drill-pipe movement. The simulated cuttings-bed is a 75cm long deposited sand bed in a horizontal section, in addition, two different types of biopolymer-based fluids with similar viscosities at a specific shear rate range are being used to compare how non-Newtonian fluids and Newtonian fluids interact with the deposited cuttings for cleaning efficiency.
Failure Rate and Repair Time Analysis of Offshore Wind Turbines
Authors: Guarda Luis Felipe , Terra Leonardo , Ramos Martins Marcelo 
Published: September 2023

Abstract
Offshore wind turbines have several advantages over onshore turbines, such as greater efficiency and the ability to generate greater amounts of energy in a more constant manner. Despite this, the Levelized Cost of Energy of onshore wind turbines is still lower than for offshore wind turbines, and the main reason for this difference comes from the operating and maintenance costs. For this reason, optimize the operating and maintenance costs of offshore wind turbines represents one of the biggest opportunities to improve the offshore wind industry. However, the lack of failure rates and repair times for the new and bigger offshore turbines prevents the feasibility to develop new reliability analysis that could improve the offshore wind turbines costs. To tackle this problem, this work presents a comparison between the 7MW Levenmouth Demonstration Turbine and a theoretical wind turbine obtained from a literature review, contrasting in this way a data-based analysis against the information available in the literature. The obtained results show the feasibility of data-based analysis and Monte Carlo Simulation comparison to failure rates validation and transfer knowledge from the onshore to offshore wind turbine industry.
Large Scale Test of Automatic Tsunami Barrier
Authors: Hamada Eigai 
Published: September 2023

Abstract
The Anti-Tsunami Laboratory (ATL), represented by Eigai Hamada, invented and developed the Anti-Tsunami Door (ATD) as a compact automatic tsunami barrier. In March 2022, ATL tested a large-scale model of a three-stage ATD unit using the Large Wave Flume (a hydraulic test facility) at Oregon State University (OSU) and confirmed its performance: (1) functioning automatically (refer to Figure 4); (2) achieving reasonable wave height reduction, which is approximately 89% of a solid barrier of almost the same height; and (3) demonstrating reasonable strength for a wooden structure under the large-scale model test conditions. Before this test, the Explosion Research Institute (ERI) simulated the wave pressure on a large-scale model ATD unit, because the wave pressure on the ATD unit is expected to be high during the large-scale model test. In this test, ATL measured the wave pressure on the surface of each stage of ATD under post-operation (fully standing) conditions and found that the measured wave pressures are almost same and somewhat higher than those which were simulated previously.
Implementing a Method for Meteorological and Oceanographic Climate and Data Evaluation
Authors: Gullaksen Joannes 
Published: September 2023

Abstract
During the initial phase of the design of an offshore renewable or sustainable energy project, it may prove useful to carry out environmental climate assessment as part of a methodological study to assess the suitability of an offshore renewable energy project. This paper presents description of extreme design mode implemented in a software application designed to support screening of meteorological and oceanographic climates. The method of estimating extreme values is controlled by the availability of data, such as known or unknown probability distributions, maximum wave height, and available time series of sample data. The implementation takes into account both global models and event models in the analysis strategy. The global model strategy describes the long-term variation of the environmental climate in terms of generic distributions, such as marginal distribution models established by adapting the entire dataset from the geographical location using different fitting techniques. In the event model strategy, the extreme value analysis includes selection of data for statistical analysis, sample selection method, model distributions, fitting methods, goodness of fit test and return period values. The criteria for choosing the fitting method are based on minimizing uncertainty and bias in the extreme value estimation, where the test of whether the adaptation method meets the criteria is carried out using a simulation technique. Other important topics, though not covered in this paper, include load analysis, which involves numerical methods for complete models. This application is based on available meteorological and oceanographic data as input to establish climate, estimate design conditions, and select and apply a theory. However, the application can also be used where time series analysis and spectral analysis are already in place. This can have benefits, such as improving the quality of environmental impact analysis.
An Investigation of the Influence of Added Mass on the Ice Loads in Various Sea States
Authors: Jiang Zongyu , Li Fang , Suominen Mikko , Tavakoli Sasan , Kujala Pentti , Hirdaris Spyros 
Published: September 2023

Abstract
Popov et al. (1967) proposed an approach to evaluate the ice loads during ship-ice impact. The approach firstly calculates the reduced mass and velocity of ship-ice system based on the principle of conservation of momentum. Secondly, it predicts the ice loads by assuming that the reduced kinetic energy is absorbed by the work of contact crushing stress. The added mass used at the first stage of Popov approach is estimated with simplified empirical formulas.
This paper attempts to introduce an improved method for the prediction of ice loads by accounting for the influence of the added mass, calculated by potential flow theory, in Popov’s approach. The evaluation of ice loads involves the effects of: 1) ship and ice geometry; 2) waves; and 3) hydrodynamic cross coupling between ship and ice.
A potential flow theory model, consisting of a ship and an ice floe, is built to calculate the added mass, wherein the ship is approaching the free-floating ice at a constant speed in random waves. The added mass is subsequently integrated into the Popov approach to evaluate the ice loads. Comparisons of results with those from the conventional Popov prediction reveal that the ice loads are considerably affected by the influence of added mass in waves. Notwithstanding this, ice loads may not be sensitive to hydrodynamic interactions.
Dynamic Response and Damage Assessment of Subsea Pipelines Under Dropped Object Impacts
Authors: Yang Kun , Sha Yanyan , Liu Zhenhui 
Published: September 2023

Abstract
Subsea pipelines transporting crude oil, liquified natural gas and carbon dioxide have been installed offshore for the past decades. However, there are many situations where heavy objects may drop from significant heights over subsea pipelines. These scenarios typically happen during crane operations on platforms, lifting operations from supply vessels, and accidental structural component failure. Such accidents can pose a significant threat to subsea pipelines due to the large mass and velocity of the dropped objects. Therefore, proper analysis and design shall be performed for subsea pipelines under accidental dropped objects impacts. However, present guidelines for the analysis and design of subsea pipelines subjected to dropped object impacts are limited and often based on simplified assumptions. The interaction of the dropped object and the impacted pipeline is often disregarded. In this study, dynamic analyses of subsea pipelines under dropped shipping containers are performed. Finite element models of steel pipelines with and without concrete coating were developed. The structural deformation and damage to both the dropped container and the impacted pipeline are considered. Numerical simulations were performed to investigate the effect of impact angle and pipeline dimensions. The contribution of concrete coating to impact resistance is also discussed. Design considerations were also proposed for dropped object protection of subsea pipelines based on numerical results.
Annotated Guidelines for the Simulation of Floating Offshore Wind Turbines in a Real Environment
Authors: Papi Francesco , Bianchini Alessandro 
Published: September 2023

Abstract
In the case of floating wind turbines (FOWTs), international design standards currently leave a larger degree of freedom to engineers in the specification of the boundary conditions for turbine simulation and certification. This is due to fact that FOWTs are still a young technology, and standards are still evolving. To analyze offshore wind turbines and estimate parameters such as AEP, fatigue and extreme loads, site-specific reference environmental conditions need to be defined. Then, a probabilistic model of the installation site must be built in order to compute lifetime quantities. Finding a trade-off between simulation number and length and good long-term estimation of fatigue and ultimate loads, as well as the selection of relevant loading metrics requires a significant amount of research or experience in the field.
The current work aims at exploiting a procedure that was developed within the H2020 FLOATECH project and made available open source with this study to the scientific community, with the objective of addressing what is required to perform a load and performance evaluation of a FOWT in a real environment. A procedure to obtain environmental conditions if the ones available in the literature do not meet the designer’s needs is first illustrated. Then, the most important parameters that need to be considered when performing an analysis of a FOWT are detailed; taking these into account and their corresponding metrics, a detailed guideline on how to define a suitable list of Design Load Cases (DLCs) is presented, as well as different methods to reduce the number of model evaluations deriving from the DLCs’ list, and thus reduce computational time.