bluuebunny/crossref_metadata_2025_split huggingface dataset:
High-efficiency continuous-wave Tm-doped fiber laser with a single fiber Bragg grating at 1942 nm
Authors: Yang Chao , Li Xin , Zheng Bowen , Li Yongliang , Ju Youlun 
Published: November 2023

Abstract
We report a continuous-wave Tm-doped fiber (TDF) laser with a single fiber Bragg grating (FBG). The Fresnel effect presenting in the passive fiber end-face and high-reflectivity FBG established the resonator. The peak wavelength of the laser was 1942.25 nm with a spectral linewidth of 194 pm. The maximum output power was 37.5 W, corresponding to a slope efficiency of 63.7% with a beam quality factor of M
2 ∼ 1.51. To the best of our knowledge, this is the highest slope efficiency of a TDF laser pumped by 793 nm laser diode.
Trickle-down strategies: integrating simulations with control loops of autonomous vessels on lab scale
Authors: Baart Fedor , Gijn Max Willem van , Boogmans Bart , Zagonjolli Migena , Zuidwijk Rob , Negenborn Rudy R. , Koningsveld Mark van 
Published: November 2023

Abstract
This study integrates strategic decisions and operational control systems in autonomous shipping. By providing ships with situational information and adding a virtual operator, we show that vessels can make informed choices regarding their route and engine settings. To demonstrate this integration, we developed new components and put these to the test in three lab experiments.
The green routing capability experiment showed the bridge between the control system of the autonomous vessel, operated via Robot Operating System (ROS), to the simulation environment of OpenCLSim. We developed a real-time variant of OpenCLSim and a communication component that could expose the state of the OpenCLSim simulation with the ROS system. This experiment showed that an autonomous vessel could follow a path provided by the simulation.
The green steaming capability experiment showed that the ship could also adapt its speed based on information from the simulations. We developed an additional communication component capable of advising the vessel about its velocity. Together with the green-routing capability, this forms the basis for more complex experiments.
The port layout experiment showed a potential use case of the green-routing and green-steaming capabilities. We created a waypoint layout similar to the port. While a ship is sailing, twelve simulations are computed every five seconds. The scenarios vary in engine order, route choices, resulting in varying emissions, fuel, and cost. We evaluated the impact of different tactics such as green-routing, green-steaming, and full-speed sailing on operational behavior like steering and engine order. Our approach, using a real-time version of a Vessel in the OpenCLSim simulation software, enabled predictive simulations to facilitate the chosen tactic based on a given strategy. Integrating simulations to evaluate the options with the control systems can develop into a valuable tool for optimizing vessel performance and reducing environmental impact in autonomous shipping operations.
Design and Build of an Autonomous Catamaran Urban Cargo Vessel
Authors: Zhang Yan-Yun , Shuai Jiangtao , Billet Jef , Slaets Peter 
Published: November 2023

Abstract
This study introduces a novel test bed, named the Maverick, which aims to advance the field of autonomous inland waterborne freight transportation and facilitate its eventual implementation. More specifically, the Maverick focuses on operating in small waterways within urban areas, aligning its application scenario with the European project AVATAR. The hull form of the Maverick was selected to be a catamaran, as it offers several advantages, including a large open deck area, high transverse stability, and excellent maneuverability at low speeds. The Maverick is equipped with two 360-degrees-steerable azimuth thrusters, one at the bow and one at the stern. This configuration makes the Maverick over-actuated, and offers more advanced motion control possibilities compared to conventional rudder-propeller actuated vessels. The Maverick is composed out of modular building blocks combined with a flexible interface, which enables it to accommodate diverse control terminals for future developments. Furthermore, to illustrate the feasibility of the Maverick within an urban context, this study also includes results of several trail tests. The interactive communication framework that was successfully employed in the autonomous sailing experiment is introduced. The Maverick offers a versatile platform for testing and developing a wide range of technologies in situation awareness, autonomous sailing, smart waterway logistics, and other interconnected domains. Therefore, this innovative research vessel can pave the way for the development of a new freight transport mode within European urban areas, contributing valuable experiences to the field.
Multi-functional and Practical Adaptive Collision Avoidance Decision-making System for Autonomous Ships
Authors: Zheng Kang-jie , Zhang Xin-yu , Liu Zhen-sheng , Kwangil Lee , Wang Cheng-bo 
Published: November 2023

Abstract
In the current landscape, autonomous navigation systems face challenges due to incomplete functionality and low integration. They also lack a comprehensive, real-time, and accurate navigation risk assessment, while operating independently from one another. To address these issues, a multi-functional and practical adaptive collision avoidance decision-making system for autonomous ships is developed in this paper. The system primarily relies on the electronic navigational chart (ENC) to effectively display the ship’s navigation situation. It establishes a collision avoidance decision-making model centered around the own ship, offering collision risk analysis, avoidance methods, and optimal timing to ensure safe navigation. The system efficiently integrates and processes multimodal maritime data from various devices, utilizing ontology-based approaches for comprehensive navigation situation understanding, which integration provides invaluable support for intelligent decision-making processes. With a user-friendly interface, excellent portability, and cross-platform interoperability, this system has undergone collaborative efforts and joint debugging with China Shipbuilding Navigation Technology Co., Ltd. during the project’s first and second phases. Notably, the system has been successfully implemented on the “High-performance Integrated Bridge System” platform of China Shipbuilding Navigation, showcasing its potential for advancement from principle prototype development to actual equipment application. By offering accurate collision avoidance decision support, this system significantly contributes to enhancing the safety of ship navigation.
A multi-sensor indoor tracking system for autonomous marine model-scale vehicles
Authors: Ponzini Filippo , Zaccone Raphael , Martelli Michele 
Published: November 2023

Abstract
Attitude estimation is a popular topic in marine engineering and robotics; the position and orientation of a vehicle are required as feedback from several control algorithms to improve autonomous navigation capabilities, such as dynamic positioning, track keeping, and autodocking. Typically, position and heading angles are provided by the Global Positioning System and compass. Usually, during the development and testing, the experiments are performed in a controlled environment, such as an indoor test tank. However, Global Positioning System systems can be unreliable due to non-negligible model scale errors or the absence of line-of-sight with the satellites. This article presents an experimental tracking system setup suitable for indoor testing facilities. In particular, the paper presents a tracking system based on a GigE camera and ArUco markers detection and a LiDAR-based tracking system relying on unsupervised machine learning techniques. The MQTT broker-based publish/subscribe message-queuing protocol allows real-time data communication and sharing. The proposed system was developed, installed, and tested in the COMPASS laboratory (University of Genoa). The two tracking systems’ outcomes have been compared. Eventually, an accuracy analysis was performed by comparing the results to the ground truth in purpose-built experiments. The proposed approach can estimate the degrees of freedom of a self-propelled model-scale vessel in an indoor testing facility without requiring active or powered markers and share the information acquired with multiple entities in real-time at a high frame rate.
Application of the EAST-BL method on a MASS system for Hazard Identification and Risk Assessment
Authors: Ventikos Nikolaos P , Siokouros Panayiotis , Koimtzoglou Alexandros 
Published: November 2023

Abstract
As can be seen through the continuous research on the Marine Autonomous Surface Ships (MASS) in recent years, several positive as well as optimistic results have been emerged, along with several concerns. In particular, the risk analysis process regarding MASS faces many difficulties as the lack of respective data may lead the estimation of probability or frequency to be extremely uncertain or even biased. To this end, the application of risk informed approaches, that are based on the traditional definition of risk, can be quite misleading. This paper presents a methodology for risk assessment on MASS based on the utilisation of the EAST-BL, a system-based methodology that combines the output of three different networks (i.e., task, social and information) for human and non-human agents of a system to identify hazards and the DNV’s framework for risk assessment from the RBAT study. The objective of the paper is to provide insights regarding the application of EAST-BL on MASS as well as the way that system-based methods can be utilised to enhance the hazard identification and risk assessment processes for MASS.
Structured Description of Autonomous Inland Waterway Barge Operations
Authors: Hagaseth Marianne , Meland Per Håkon , Wille Egil 
Published: November 2023

Abstract
Autonomous and unmanned shipping is revolutionizing the maritime industry by introducing a paradigm shift on how to design the vessels and supporting land-side infrastructure. Currently, there is a lack of formalisms on how to plan for such operations, determining the varying degrees of autonomy and human responsibility, whilst ensuring safety and security. This paper describes fundamental concepts of autonomy in the context of ships. These are then applied in a methodology used to create systematic and structured descriptions for the operation of autonomous ship systems. The examples we use are based on ongoing efforts related to a planned autonomous inland waterway (IWW) barge operation. Finally, we show how the descriptions can be used in conjunction with existing safety and security analysis techniques. Our experience with this methodology is that it allows for a smooth transition from the autonomous ship system design phase to the assessment of the same system using UML notations. We believe that the same methodology can be easily applied to the other use cases and similar systems elsewhere.
The shift toward autonomous European inland waterway shipping: Identifying the gaps in the emerging socio-technical system
Authors: Saha R , Lundh M , MacKinnon S N 
Published: November 2023

Abstract
The introduction of automated solutions for inland waterways shipping supports the European vision for a sustainable and greener shift within maritime management and logistics. Despite increasing investments, impressive technological advancements, and active discussion to solve the regulatory and business model barriers, socio-technical aspects are still less studied in the preparation for the future of autonomous shipping. This study examines stakeholder and technology roles to map the gaps and challenges created in this emerging space using a system theory approach, specifically a recently developed work design system analysis tool named Change Agent Infrastructure (CHAI) analysis [1]. This framework was chosen to better understand the likely changes of the system with the introduction of automated technology and higher degrees of automation and digitalization in the European inland waterways. The analysis identifies that there are multiple receivers of the change and regulatory bodies will also be actors with considerable responsibilities to direct these changes.
Smart Ships and implications in logistics chains a case study in Zeeuws Vlaanderen
Authors: Caballero Rosas A , Verduijn T 
Published: November 2023

Abstract
Autonomous shipping is expected to be gradually adopted in the coming years. While many scientific studies in the field have focused on technological development, recent research has started to explore the effects of this innovation on the cargo transportation industry. This study investigates the economic dynamics that can drive logistics entrepreneurs to adopt teleoperated barges, a specific type of smart shipping. By conducting a case study of cargo transportation between two companies using roundtrips with trucks and barges, the study evaluates a modal shift to intermodal transport and looks into the conditions that are affected if barge teleoperation is implemented. A major conclusion of the study is that the transport distance, the equipment size, and the mix of captain-only tasks versus all the sets of crew tasks affect the expected economic gains that are obtained as a result of implementing smart shipping. In this case, a conventional modal shift to waterborne transport is already economically attractive. When opting to operate a smaller barge, teleoperation becomes preferable when a shore-control captain can only focus on exclusive sailing tasks and when more than one ship is monitored simultaneously.
Vortex filament method 3D analysis of design parameters for counter-rotating axis floating tilted turbine
Authors: Andersson E , Bernhoff H , Goude A 
Published: November 2023

Abstract
The Counter-Rotating Axis Floating Tilted turbine (CRAFT) is a new design for floating off-shore wind power, which utilizes a low center of gravity and allows the tower to tilt to mitigate costs for platforming.
In this study, 3D simulations of the CRAFT have been performed to investigate the effect from the tower’s tilt angle on the aerodynamics of the turbine using a vortex filament method. Due to lack of empirical data of the CRAFT, the method has been benchmark tested against a previous project on a vertical axis wind turbine.
Using this method, the blades’ twist angle has been set to achieve good lift-to-drag ratio along the entire blade. Furthermore, the blades’ chord length has been determined for optimal Tip Speed Ratio (TSR) 6 when the tower is tilted 30 degrees from vertical position.
The CRAFT has been simulated vertically and tilted 15°, 30° and 45°, for TSRs ranging between 4 and 9. The power coefficients (CP
) and normal forces have been determined, and velocity plots are presented to show how the near-wake develops.
The results from this study serves as a basis for further development and design of the CRAFT.
Pile design for X-rotor offshore wind turbine
Authors: Dong Jing , Silva Adriana Correia Da , Muskulus Michael 
Published: November 2023

Abstract
For the foundations of traditional offshore structures in oil and gas industry, the dominant load is in vertical direction. For wind turbines, especially for vertical axis wind turbines, the lateral loads are increased significantly, which makes them the key element of the pile design. The X-rotor offshore wind turbine is a novel concept which is a hybrid of vertical and horizontal axis wind turbines. This paper aims at giving a detailed solution for the pile design of X-rotor type offshore wind turbines based on the existing guidelines and to gain an insight in the influences of the cyclic loads on the pile parameter selection. The pile capacity design and the pile performance design are executed and then the influence of the piles to the natural frequencies of the wind turbine is evaluated.
Start-up Dynamics of Vertical Axis Wind Turbines: A Review
Authors: Lough Jamie , Asim Taimoor , Coull Scott , Marshall Andrew , Islam Sheikh Zahidul , Amber Ityona 
Published: November 2023

Abstract
Vertical Axis Wind Turbines (VAWTs) are becoming increasingly popular for wind power extraction due to their simpler design, lower manufacturing and maintenance costs. The omni-directionality of these power generating machines make them more suitable for operation both under lower wind speeds and highly transient winds. The key wind power extraction component of VAWTs is their rotor, which is conventionally either Drag-based or Lift-based, with the latter being more widely studied in the published literature due to its higher power coefficient compared to its counterpart. The lift-based rotor comprises of aerodynamically profiled blades, while the drag-based rotor comprises of thin cup-shaped blades. The start-up of both these types of VAWT rotors has been an area of active research in the last decade. These studies have been conducted using numerical and experimental methods focusing on key parameters related to the start-up dynamics of VAWTs. Many of these research studies complement each other’s findings, however, there are also a number of aspects where there are disagreements and/or significant knowledge gaps that need to be highlighted in order to accelerate scientific efforts strategically. In the present study, we aim to address these challenges through a thorough and critical review of the published literature on VAWTs’ start-up dynamics, leading towards the identification of key knowledge gaps.
Direct drive double fed wind generator
Authors: Ostović Vlado 
Published: November 2023

Abstract
An electric machine topology characterized by single tooth winding in both stator and rotor is presented. The proposed machine is capable of operating as a direct drive double fed wind generator (DDDF, D3F), because it requires no gearbox. A wind turbine drive built around a D3F generator is cheaper to manufacture, requires less maintenance and has a higher energy yield than its conventional counterparts. The all tooth wound generator of a D3F turbine has a superb volume utilisation and lower stator I2R losses due to its extremely short end windings, efficient cooling and reduced active length. Both stator and rotor of a D3F generator can be manufactured in segments, which simplifies its assembly and transportation to the site, and makes its production cheaper.
Aero-structural coupled optimization of a rotor blade for an upscaled 25 MW reference wind turbine
Authors: Werthen Edgar , Ribnitzky Daniel , Zerbst David , Kühn Martin , Hühne Christian 
Published: November 2023

Abstract
One major challenge of the wind turbine industry is the reduction of the levelized cost of energy (LCoE) while following the strong demand for a higher annual energy production (AEP). To meet these goals, larger wind turbine sizes are required. The common method of upscaling existing wind turbine designs comes along with the problem of faster growing blade masses and costs compared to the AEP. Investigations in new technologies to improve the structural efficiency of larger blades can be supported by aero-structural coupled optimizations. The present work introduces a two-step aero-structural coupled design process to capture the multi-disciplinary trade-offs between costs and AEP, aiming at minimizing LCoE for a 25 MW wind turbine. In a first step, a preliminary aero-structural optimisation is carried out using simplified and fast methods. The output is then refined with respect to additional design criteria with an advanced optimization process, including an aero-servo-elastic coupled loads analysis. The process is applied to a 25 MW blade, upscaled from the IEA 15 MW reference wind tubine. Based on the results of an utilization analysis, the structural design is adapted, and a stiffness optimization is performed. The optimum airfoil positions are identified to reduce the amount of material while limiting losses in the aerodynamic performance. The obtained blade designs facilitate a consistent AEP compared to the upscaled reference design. A mass reduction of 35% could be achieved, which results in a reduced LCoE of 1.7% compared to the purely upscaled blade design.
An assessment of electrolyser portfolio for offshore hydrogen production considering its key properties – efficiency, ramp rate and capacity
Authors: Andreae E , You S , Bindner H W , Petersen M 
Published: November 2023

Abstract
Wind-electrolyser systems that produce green hydrogen – including hydrogen-generating offshore energy hubs – have received a lot of attention. The electrolyser capacity in such systems can be arranged in different configurations by varying the location setup of the electrolysers. The setup influences not only the dynamic performance of electrolysers but also the system economics. This paper analyses the differences in the dynamic performance of electrolysers in a centralised and decentralised setup from a technical and economic perspective, when the target is to produce as much renewable hydrogen as possible using today’s electrolyser technology. The economic effects of scaling for various wind turbines under different wind conditions are incorporated in the analysis.
Differences in electrolyser efficiency, start-stop, ramping, operation range and scale are modelled, and the models are applied to a case study depicting an offshore energy hub. Using a representative wind profile of fluctuating conditions and considering identical electrolyser ramping and efficiency for the same turbine configuration, the analysis shows that the single electrolyser solution (centralised), where the electrolyser is sited at a substation, gives a better levelized cost of hydrogen than the alternative setup (decentralised) with multiple in-turbine electrolysers.
Resilience to storm conditions of power systems with large dependencies on offshore wind
Authors: Forsberg S , Thomas K , Bergkvist M , Göteman M 
Published: November 2023

Abstract
The ongoing transition towards large installations of offshore wind and the electrification of the transport sector and other critical infrastructures introduce new vulnerabilities to the society. Large dependencies of power production from offshore wind are expected in the next decades, but there are large knowledge gaps regarding the power production reliability under severe weather conditions. Simultaneously, weather extremes may increase in frequency and intensity, driven by climate change. In this paper we investigate the resilience of a power system subject to a hurricane event. The power system is based on the IEEE39-bus New England system but with different scenarios for increasing penetration of offshore wind. We find that an offshore wind penetration level of 30% or less results in a power system resilient to hurricane events, with no need for load disconnection. However, when increased to 40% offshore wind penetration, 650 MW corresponding to 10% of the total load demand gets disconnected during the storm peak. With a penetration of 50% offshore wind, the disconnected load ranges from 2.2 GW of load corresponding to 1/3 of the total load demand, to a total power system blackout.