bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiple Model Adaptive Estimation Coupled With Nonlinear Function Approximation and Gaussian Mixture Models for Predicting Fuel Consumption in Marine Engines
Authors: Taghavi Mahmood , Perera Lokukaluge Prasad 
Published: September 2023

Abstract
Digital twin type models can be developed for physical systems that are complex nonlinear a system of systems (SoS). However, such models are usually difficult to represent by linear equations. Therefore, an adequate linearization technique should be introduced. Therefore, linear models as digital twins can be interpreted easily and need much less computational power when applied to various industrial applications. On the other hand, a linearization approach can increase the respective system-model errors and impose significant constraints on the models of SoS, i.e., since linear models can be applicable only in limited operating regions. This research study aims to combine positive characteristics of both linear and nonlinear modelling into a digital twin development framework by having the properties of linear digital twin models locally while the model framework is covering the whole operating region of the SoS. An industrial application of marine engines as an SoS is considered for this study, where the respective models have been used to predict engine fuel consumption.
For this purpose, firstly, a dataset is selected from a marine engine of a selected ocean-going vessel. Then, several localized linear operational regions of the respective data set are identified using an unsupervised data-driven technique, i.e., on the engine propeller combinator diagram. For developing the localized models: firstly, the Gaussian Mixture Models method is used to cluster the data points into different operational regions of the engine propeller combinator diagram. Then, a nonlinear model of the relationship between features is developed in each cluster using the polynomial regression approach. Then, these models are combined using the Multiple Model Adaptive Estimation (MMAE) method to create an overall model for the marine engine as an SoS. The same model is utilized to predict the respective fuel consumption based on engine operational conditions.
Numerical Modelling of the Performance of Floating Fish Pen in Harsh Environmental Conditions
Authors: Nasyrlayev Nazhmiddin , Dyson Ashley , Kefayati Gholamreza , Tolooiyan Ali 
Published: September 2023

Abstract
The growing demand for high-quality protein sources, coupled with technological advancements, has recently created the need, and facilitated opportunities for offshore aquaculture in high-energy areas. Although based on experience gained through many years of practice in low-energy areas, aquaculture companies prefer to use traditional fish pens in high-energy regions, the short- and long-term performance of the pen and mooring components in harsh environments are not well studied. In this study, a numerical model of a slender fish pen is created in the Finite Element (FE) environment to study the pen’s response to harsh environmental loads, including currents and waves. To assess the reliability of the FE model, a validation exercise was conducted for both current-only and combined current and wave conditions, which led to good agreement between the published data and the modelling conducted in this study. The model is then employed in total of 1440 simulations to analyze various pen arrangements with different angles of attack of waves and currents concerning a range of current intensity and wave height. Further consideration is given to the performance of pens at high current velocity and wave height (e.g., 2 m/s and 3 m) while observing the volumetric changes of the pen and distribution of the tension load in mooring lines.
Hydrodynamic Forces of Subsea Small-Diameter Pipeline in a Deep/Wide Trench
Authors: Liu Zinan , Cheng Liang , Ren Chengjiao , Griffiths Terry , Tong Feifei 
Published: September 2023

Abstract
Accurate predictions of the hydrodynamic forces on a pipeline or cable in a trench are of both fundamental and practical significance. Existing design guidance (DNV-RP-F109) enables forces to be estimated based on a simplified model of a pipeline in a trapezoidal trench with very limited dependence of hydrodynamic forces on incoming flow and some trench geometry parameters, such as the slope of the trench θ, the trench-width-to-pipeline-diameter ratio W* and the trench-height-to-pipeline-diameter ratio H*. The present study conducts a series of two-dimensional (2-D) and three-dimensional (3-D) direct numerical simulations of steady flow past a pipeline placed at the bottom of a smooth trench over a range of trench configurations (θ = 0°–30°, W* = 3–20 and H* = 1–20). The pipeline Reynolds numbers vary from 500 to 3900 based on incoming steady flow velocity and pipeline diameter, meaning that these results are a preliminary investigation of the problem rather than representing typical pipeline/cable/trench/ flow conditions. This paper explores the dependence of trench configurations on flow characteristics and hydrodynamic forces.
Sea Trials of Multiple Heterogenous Cruising AUVs and ASV With Basic Formation Control
Authors: Sato Takumi , Kim Kangsoo , Sasano Masahiko , Okamoto Akihiro , Inaba Shogo , Kondo Satoshi , Matsumoto Hiroshi , Murashima Takashi , Fujiwara Toshifumi , Osawa Hiroyuki 
Published: September 2023

Abstract
The National Maritime Research Institute (NMRI), in collaboration with the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), is conducting research and development of seafloor observation technology using multiple autonomous underwater vehicles (AUVs) and one autonomous surface vehicle (ASV) under the 2nd SIP project “Innovative Technology for Deep Sea Resource Exploration.” A group of heterogeneous AUVs with different design concepts may have to be controlled when operating multiple AUVs simultaneously. In this study, we developed a basic formation control system that enables various AUV control with minimal software and hardware modifications to ASV and AUVs and successfully tested it in actual sea conditions. Four AUVs and one ASV from different manufacturers were used in the sea trials. The basic formation control system kept all AUVs within acoustic communication range and successfully acquired seafloor topographic data. The tests demonstrated the capability of basic formation control with heterogeneously navigated AUVs. This paper reports and summarizes the test results of those basic formation control tests.
A Numerical Simulation Tool of Ship Navigation in Ice Under Various Ice Conditions
Authors: Li Fang , Kujala Pentti 
Published: September 2023

Abstract
The performance of ships going through ice-covered water is a main focus of the design of such ships. Estimation of ships’ ice-going performance has been a challenging task for decades due to the complexity in the modelling of ship-ice interaction process. To date, empirical formulae have been the mostly used method in ship design practice. Over the last decade, numerical simulation has emerged as an alternative technique for the evaluation of ships’ ice-going performance. A ship-operation-in-ice simulator has been developed at Aalto University during the past few years. The simulator supports diversified operation senarios such as going straight ahead or turning in level ice, navigation through narrow ice channel, breaking out of channel, as well as going through compressive ice channel. The simulator is designed as a Matlab Application with user interface and as well support running through scripting. It requires light computation and can be executed with a normal PC within a relatively short time. This paper introduces its overall structure, modelling techniques and associated functionality. Examples of various operation scenarios are given to illustrate the functionality of the simulator. Comparisons with model scale tests and full-scale measurements are provided to demonstrate the validity of the simulator. Finally, the planned further development is described.
Wave-Induced Dynamic Seabed Response Around a Submerged Breakwater With Dynamic Permeability
Authors: Li Zhengxu , Jeng Dong-Sheng 
Published: September 2023

Abstract
In this paper, an integrated numerical model with Open-FOAM for the wave-breakwater-seabed interactions problem is presented. Unlike previous studies available in the literature, the present model adopts Biot’s u-p approximation and considers dynamic seabed permeability, which is a function of pore-fluid pressures in the seabed. The proposed model is verified against the existing experimental data. The numerical examples show that dynamic permeability has a significant effect on wave-induced dynamic soil responses, which will cause a deeper and wider liquefaction zone compared with the conventional models with constant permeability. Ignoring the effects of dynamic permeability could significantly impact the transient seabed liquefaction depth and the stability of offshore structures.
A Framework for Defining Risk-Based Inspection Plans for Subsea Equipment
Authors: Schleder Adriana M. , Maturana Marcos C. , Ramos Martins Marcelo , F. F. Frutuoso e Melo Paulo , Barros Leonardo de Oliveira , Orlowski Rene Thiago Capelari 
Published: September 2023

Abstract
Cost and risk optimization is a central issue in the offshore Oil and Gas sector, and risk-based approaches has been more and more employed to assist the segment in the concretization of that goal. In this sense, the use of Risk Based Inspection by the oil industry has increased. The inspection procedure aims mitigating the uncertainty related to the asset degradation state, enabling a better quantification of the actual damage, and, consequently, increasing the accuracy of remaining life projections. However, the costs involved in offshore subsea inspections are considerable. Therefore, the optimization of inspection plans plays a crucial role in the definition of an asset management program economically balanced. To perform an efficient optimization, it is important not only obtain an effective optimization algorithm but also achieve a high quality of the information used as input. In other words, an adequate definition of the risk indexes used is necessary, as well as the entire process used to quantify them. In this context, this paper presents a framework for obtaining the optimized inspection plans, starting from the assessment of the risk associated with the failure modes, moving on through the process of defining risk indices and, finally, presenting the optimization process itself. In this way, the framework proposed presents all the phases necessary to obtain optimized inspection plans, including the stage of preparation for the optimization process. Finally, the application of the proposed framework is illustrated by the elaboration of the inspection plans for a subsea manifold.
Numerical Simulation of the Wave-Induced Drift of Disc-Shaped Floating Plastic Debris
Authors: Westerkamp Diederik , Rakotonirina Andriarimina Daniel , Sainte-Rose Bruno , van den Bremer Ton 
Published: September 2023

Abstract
Floating plastic debris poses a significant threat to the health of the world’s oceans and ecosystems. Understanding the pathways of floating marine litter is crucial in designing effective solutions to mitigate this problem. The Ocean Cleanup aims to build simple but reliable numerical models to better predict plastic accumulation zones. In this context, a Lagrangian point-particle model has been developed that can help better understand wave-induced drift. The continuous and the discrete phase are coupled in a one-way fashion using a micro-scale Euler-Lagrange approach. The Maxey-Riley equation is modified to account for disc-shaped objects, variable submergence, and two-directional drag correlation. By comparing our numerical predictions with experimental work, we demonstrate that floating discs can experience up to 73% increased wave-induced drift compared to Stokes drift. We show that the non-Lagrangian behaviour of objects is mainly dependent on the water-plastic density ratio and its size compared to the wavelength. Two key physical mechanisms contributing to increased drift effects are investigated, both related to the particle’s variable submergence. Finally, we provide an overview of the computational limitations and the model sensitivities that can help to improve the accuracy of numerical wave-induced drift predictions.
Upheaval Buckling Analysis of the Large Deformation of Unbonded Flexible Pipe Under Cyclic Pressure and Temperature Loadings
Authors: Liu Jian , Zhu Linfa , Tan Zhimin , Roberts Andrew , Murray Sean , Trousdale Euan , Patrocinio Juliana , Casanovas Revilla Clara , Lopes de Castro Mario Augusto 
Published: September 2023

Abstract
The upheaval buckling (UHB) behaviour of buried unbonded flexible pipes governs the cost of mitigation measurement in terms of material and installation. The traditional industry approach to mitigate UHB risk of flexible pipes is to design them to stay in place, which is inherited from rigid pipelines technology where a catastrophic buckling can be triggered by small perturbations within material elastic region. On the other hand, unbonded flexible pipes of multiple layer construction are designed to accommodate large pipe deformation without compromising their structural integrity. By allowing large upwards movement of flexible pipes within the soil cover, an alternative UHB analysis design approach will present a better reality compared with the stay in place design approach.
The present paper investigates the large deformation characteristics of flexible pipe interacting with soil cover beyond its mobilization displacement, i.e., post-buckling behaviour. The paper also explores a method to account for the effects of potential cyclic pressure/temperature loadings where the pipe reversible displacement might be resisted by ‘fill in’ material. The study will use finite element analysis method. Sensitivity studies are performed to investigate the impact of different pressure loading history during the pipe service life on the final pipe deformation configuration and its UHB risk of breaching soil cover. A comparison is also made to the traditional stay in place mitigation approach to demonstrate the improvement, for example, the volume of rock dump, without violating both the pipe functional requirements and structural integrity.
Application of Different Methods to Determine the Ultimate Strength of Ships in Bending
Authors: Lindemann Thomas , La Ferlita Alessandro , Di Nardo Emanuel , Kaeding Patrick 
Published: September 2023

Abstract
Displacement controlled nonlinear finite element analyses are performed to determine the ultimate strength of three different vessel types in vertical bending. Parametric finite element models are proposed for a bulk carrier, double hull VLCC and for a container vessel. The influence of different model parameters on the collapse behavior is shown for sagging and hogging condition. The influence of initial imperfections of the stiffeners and the attached plating due to welding is taken into account. The results are validated for all different ships against Smith’s method. An inhouse code has been developed following the Common Structural Rules (CSR) proposed by the International Association of Classification Societies (IACS). The Smith’s method based results of intact and damaged ships in vertical bending have been used to train a Deep Neural Network (DNN) as machine learning approach. The applied network architecture is composed of two layers with a high-level number of activation units. The applicability of DNN to predict rapidly the ultimate strength of ships in vertical bending is demonstrated exemplarily for the same bulk carrier, double hull VLCC and the container vessel. Furthermore, DNN is used to determine the shift of the neutral axis for the different vessels.
Performance Analysis and Optimization of a Wave Energy-Based Zero-Liquid-Discharge Hybrid Desalination System
Authors: Glosson Gabriel , Filho Faete , Chen Jinbo , Abdel-Salam Tarek , Duba Kurabachew 
Published: September 2023

Abstract
The demand for freshwater is increasing globally, particularly in areas with limited water resources. Desalination, the process of removing salt and other minerals from seawater, is one solution that can help meet this demand. However, traditional desalination methods can be energy-intensive and generate significant amounts of waste. To help address these issues, a hybrid wave-to-water desalination system that combines reverse osmosis (RO) with supercritical water desalination (SCWD) can be used to produce freshwater from seawater. SCWD is used to treat the brine produced by RO, while the RO system produces fresh water at a lower energy cost. The system utilizes a wave energy converter (WEC) to harness the energy of ocean waves to power the desalination process by using the motion of waves to directly pressurize the seawater feeding into the RO system. Using ocean waves as an energy source makes the system renewable and reduces the carbon footprint of the desalination process. This paper presents a numerical model of a small-scale zero-waste desalination system powered by off-grid renewable energy along with a sensitivity analysis to determine the optimal configuration of key parameters of the system. An oscillating surge wave energy converter (OSWEC) was selected for the current study to directly pressurize the ocean water to meet the minimum pressure requirement of the RO. The numerical model of the water desalination system was developed using MATLAB-Simulink. WEC-Sim was used to develop the wave energy converter subsystem. A sensitivity analysis was conducted using an irregular wave pattern with a wave height of 0.117 m and a period of 1.68 s to determine the optimal combination of the power take-off (PTO) volumetric displacement, accumulator size, and RO membrane type for the system. Results showed that the type of RO membrane and the PTO volumetric displacement had a much larger impact on the water production rate than the accumulator volume.
A Novel Numerical Model for Computing the Global Response and Fatigue of a Steel Catenary Riser Based on Absolute Nodal Coordinate Formulation
Authors: Hou Jing , Jia Lusheng , Liu Yi , Wang Dejun , Jia Xu , Zhang Cheng 
Published: September 2023

Abstract
Steel catenary risers (SCRs) are widely used in ocean engineering, whose dynamic performance is particularly critical to the safe operation of offshore oil and gas development. In order to fully consider the nonlinear factors of SCRs, a novel numerical model has been established based on the absolute nodal coordinate formulation (ANCF) in this paper. The position and slope coordinates are used in global framework to avoid coordinate transformation, and the accurate geometric relationship is introduced to describe the geometric nonlinearity of structural deformation. A hysteretic riser-soil interaction model is applied to simulate the nonlinear seabed force while the Morrison equation is used to compute the nonlinear current and wave forces. The overall static and dynamic equilibrium equations, deduced by the principle of virtual work, are numerically solved by Newton-Raphson and Newmark-β methods, respectively. The proposed model is compared with the software OrcaFlex in the numerical simulation for a typical SCR, following by a discussion on the response characteristics of the SCR. The model is proved to reliable to evaluate the dynamic performance and fatigue damage of SCRs, which can further support their engineering designs.
Spatial Distribution Characteristics of Ice Pressure Loads Under Turning Operations in Level Ice
Authors: Ge Yuhui , Ding Shifeng , Liu Renwei , Wang Aimin 
Published: September 2023

Abstract
There is variability in the degree of danger encountered by different hull areas when turning in level ice, so predicting the trend of load characteristics with turning angle in advance can improve navigation safety. In this paper, we use a well-developed numerical simulation method, A more reasonable turning condition was selected, and the Weibull distribution is used to describe the numerical results. The collision probability of ice pressure along the hull area under different turning angles are analyzed by probabilistic statistical methods, and the trend of ice pressure peak with angle at typical positions is studied to reveal the intrinsic relationship between ice pressure load characteristics and turning angles.The results showed that the collision mainly occurred in the inner midship at the beginning of the turn, and gradually shifted to the bow and the shoulder area as the turning angle increased; when the turning angle tended to be horizontal or vertical with the sea ice, the collision probability in the outer midship increased.
Investigation on Layout Optimization of Helical Strakes on Marine Riser
Authors: Deng Pengqian , Fu Shixiao , Zhang Mengmeng , Ren Haojie , Xu Yuwang , Sun Tongxiao 
Published: September 2023

Abstract
Helical strakes have been widely used in ocean engineering to suppress vortex-induced vibrations (VIV) of risers. To reveal the optimal layout scheme of helical strakes in engineering, a prediction method base on the non-iterative frequency domain is applied to investigate the VIV responses of risers with different strake coverage rates in this paper. On this basis, the multi-objective optimization algorithm is further used to obtain the optimal layout scheme of helical strakes in engineering. Comparisons between the prediction result and the experimental result under uniform flow are conducted to verify the feasibility and reliability of the prediction method. Results show that the coverage rate and position of strakes have a great influence on the fatigue damage rate and the total drag of the riser undergoing VIV, and it is not always optimal to cover helical strakes from the top of the riser.
Experimental Investigation on Response of Ship Rolling Motion Coupled With Liquid Sloshing
Authors: Wang Yunhe , Jiang Shengchao , Zhou Tongming 
Published: September 2023

Abstract
Ship motion coupled with sloshing of three partially filled prismatic tanks is analyzed experimentally in a towing tank. The results show that the sloshing can increase the natural period of ship motion and another peak caused by the sloshing inside the tanks can be seen at a lower period. In addition, anti-rolling effect under low filling conditions and enhanced-rolling effect under high filling conditions are observed, depending on the dominant force, namely, the hydrostatic force and the hydrodynamic force for different filling depths. The internal sloshing flow is able to generate the restoring moment and overturning moment at both low-filling conditions and high-filling conditions, respectively, leading to the suppressed and enhanced effect on ship rolling responses. It is also found that if the filling depths of the three tanks are not the same, the ship rolling motion will be reduced significantly, especially at the resonant period of ship rolling motion.