bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of illumination on the current conduction mechanisms of the Au/C20H12/n-Si Schottky barrier diode (SBD)
Authors: Bengi Seda 
Published: November 2023

Abstract
Using the I-V characteristics both in the dark and under varied illumination-intensities (50–250 mW.cm−2) by 50 mW.cm−2 steps in the wide range bias-voltage (±5 V), specific fundamental electrical and photo effects parameters of the Au/C20H12/n-Si SBD were examined. Due to the creation of electron–hole pairs and their drift in opposite directions under the influence of an electric field, the value of photocurrent in the reverse bias (Iph) increases when illumination density is increased. The barrier height (ΦB0) tended to decrease due to the increase in photocurrent, while the diode’s ideality factor (n) increased with increasing illumination intensity. Also, the Schottky structure’s open-circuit voltage (Voc), short circuit current (Isc), filling factor (FF), and efficiency (η) were determined to be 0.358 V, 95.5 μA, 33%, and 0.028% under 50 mW.cm−2, respectively. The Rs and Rsh values found using Ohm’s law are a vital function of illumination and voltage which decrease with increasing illumination intensity. Additionally, using the forward bias I-V data and accounting for the bias dependent of the effective barrier height (Φe) and ideality factor n(V) for different illumination intensities, the energy density distribution profile of surface states (Nss) was obtained. According to these results, the organic interlayer consisting of C20H12 is light-sensitive and suitable for optoelectronic devices such as photodetectors and photodiodes.
Primordial stochastic gravitational wave backgrounds from a sharp feature in three-field inflation. Part I. The radiation era
Authors: Aragam Vikas , Paban Sonia , Rosati Robert 
Published: November 2023

Abstract
The detection of a primordial stochastic gravitational wave background has the potential to reveal unprecedented insights into the early universe, and possibly into the dynamics of inflation.
Generically, UV-complete inflationary models predict an abundance of light scalars, so any inflationary stochastic background may well be formed in a model with several interacting degrees of freedom.
The stochastic backgrounds possible from two-field inflation have been well-studied in the literature, but it is unclear how similar they are to the possibilities from many-field inflation.
In this work we study stochastic backgrounds from more-than-two field inflation for the first time, focusing on the scalar-induced background produced during the radiation era by a brief turn in three-field space.
We find an analytic expression for the enhancement in the power spectrum as a function of the turn rate and the torsion, and show that unique signatures of three-field dynamics are possible in the primordial power spectrum and gravitational wave spectrum.
We confirm our analytic results with a suite of numerical simulations and find good agreement in the shape and amplitude of the power spectra.
We also comment on the detection prospects in LISA and other future detectors.
We do not expect the moderately large growth of the inflationary perturbations necessary for detection to cause a breakdown of perturbation theory, but this must be verified on a case-by-case basis for specific microphysical models to make a definitive claim.
The Application of 5G Wireless Communication in Maritime Environment
Authors: Wu Jianming , Yang Kun , Zeng Hao , Zhang Shuo , Ding Jianjun , Jiang Xue 
Published: November 2023

Abstract
Recently, 5G wireless communication have been rapidly adopted for maritime applications. As a result, significant progress has been made in the ocean digitalization. 5G features with low latency, high reliability, and a large bandwidth, which satisfies the requirements of maritime applications. Due to significant differences between land and marine radio propagation environments, the maritime communication encounters a large challenge for providing maritime users with reliable data communication service. In order to solve the abovementioned challenge, we designed a maritime 5G terminal and tested it on an unmanned surface vehicle (USV) in the Lanyue Lake of Zhejiang Ocean University. The test data were collected, and the corresponding data analysis are presented, which includes signal strength, signal reception quality, upload and download data rate. The received signal level (RSL) and transmission data rate obtained by the maritime 5G terminals demonstrate great potential of meeting the communication requirements of the maritime users. It is also can be found that the RSL and the data transmission rate of the maritime 5G can be used for the remote control of the unmanned ships, with the signal strength at sea up to -89.45 dBm, and maximum rate up to 226 Mbps.
Comparing Multiple Extended Object Tracking with Point Based Multi Object Tracking for LiDAR in a Maritime Context
Authors: Baerveldt Martin , Hem Audun Gullikstad , Brekke Edmund Førland 
Published: November 2023

Abstract
In this paper, we compare a recently developed multiple extended object tracking method with a point-based tracker for maritime applications by evaluating the methods on both real and simulated LiDAR data. Being able to track other vessels is a key part of maritime situational awareness, and multi-object tracking is well suited to this task. Traditionally, multi-object tracking uses the point approximation to simplify the target tracking problem, meaning that an object is assumed to only generate a single measurement. With recent advances in sensor technology, this approximation is no longer valid. Multiple extended object tracking instead makes use of methods that estimates the extent of a target using all available measurements. However, the target models used in extended object tracking are by necessity more complex. We compare these two approaches on real and simulated LiDAR data, which was gathered by tracking smaller vessels. We find that the extended object method has greater performance on simulated data and experimental data with comparatively little wake clutter. However, on experimental data with more wake clutter, the point-based method outperforms the extended object method since it is less sensitive to the disturbance caused by wake clutter. We can conclude that multiple extended object tracking methods have the potential to be more accurate for LiDAR data, but since the models are more complex, measurement sources need to be modeled correctly.
Study on autonomous ship enhancement by optimizing the object detecting algorithms
Authors: Jiang Xue , Zhang Xinhui , Yang Kun , Zhao Penghui 
Published: November 2023

Abstract
The accuracy and efficiency of object detection is the key technology to spread autonomous driving. In order to address issues such as missed and false detection in traditional target detection algorithms, deep learning technology is used to optimize the ship target detection model as well as the attention mechanisms in this article. Specifically, this paper proposes an improved model based the traditional YOLOv5s algorithm, and a self-created ship dataset is also provided. To refine ship target detection, various attention mechanisms were implemented and compared, including CBAM, ECA, GAM, SimAM, and SK-Net. Through comparative analysis of the effects of these mechanisms, GAM was identified as the optimal choice. The experimental results indicate that the mean average precision (mAP) of detecting ship targets was augmented by 1.0% following the incorporation of GAM. The YOLOv5s-GAM model is therefore deemed as an effective target detection approach in enhancing the safety of ship autopilot, with potential applications in the future.
Evaluation of an autonomous, short sea shipping feeder-loop service through advanced simulations
Authors: Tangstad Espen J. , Mørkrid Odd Erik , Nordahl Håvard , Krause Stefan , Mateienko Denys , Dæhlen Jon Schonhovd , Johanson Kenneth 
Published: November 2023

Abstract
Traditionally, container-freight being shipped from central Europe to the coast of Norway has been transported either by road, or by larger containerships to central ports. For the past 3 years the AEGIS consortium has worked to develop a new, disruptive short sea shipping feeder-loop service based on mother and daughter ships [1]. The hypothesis is that introducing smaller, autonomous, battery-powered vessels into the fjords of Norway would open new business areas, provide access to remote regions, and allow shipping companies to take on cargo that could not previously be transported by water. Such a transport system has the potential of reducing cost, GHG emissions and external costs, while increasing frequency of service and the waterborne cargo volume in Europe. One of the main challenges of the mother-daughter logistic system is how transshipment affects defined key performance indicators (KPIs), especially in terms of cost. For this purpose, the SIMPACT tool [2] was developed in the H2020 projects AEGIS and AUTOSHIP. The tool allows for rapid iterations of maritime logistic systems through discrete event scheduling, and estimation of energy, fuel, emission, and cost.
This paper will present results from a case-study on two different daughter ship concepts. The concepts are evaluated through cost and environmental KPIs presented in [1], in addition to external costs based on the European handbook on the external costs of transport [3].
Results from the case-studies indicate that transport systems including green daughter-vessels have the potential of being cost competitive and would lower externalities compared to the baseline truck transportation system.
VAWT support structure mass sensitivity due to aerodynamic load scaling
Authors: Silva Adriana Correia da , Muskulus Michael 
Published: November 2023

Abstract
The X-rotor wind turbine is an X-shaped hybrid vertical axis wind turbine whose power take-off is done by horizontal axis rotors located at the tip of the lower blades. Based on an initial basic study, the present study developed a preliminary jacket design as the turbine support structure. Steady aerodynamic loads were obtained from an actuator cylinder model and dynamic load simulations including wave loads were performed. The structure was checked according to fatigue damage and maximum yielding for representative site-specific load cases for fatigue and ultimate limit states. Even though the use of a conventional jacket was shown to be feasible for the new turbine concept, the overall mass of the support structure obtained by the higher fidelity model was higher than the initial prediction. The design was driven by the fatigue damage, caused by large cyclical loads on every rotor rotation. The effect of a hypothetical aerodynamic load reduction on the jacket mass was investigated. The developed design methodology was also applied to the design of equivalent jackets after a load reduction of 75% and 50% and the mass of the structure was shown to be sensible, with a respective reduction of 25% and 48%. This result demonstrates that different design strategies that influence the magnitude of the aerodynamic loads (e.g. the control strategy) could lead to a more cost-efficient jacket design.
The influence of journal bearings on the gearbox dynamics of a 5 MW wind turbine drivetrain
Authors: Siddiqui Muhammad Omer , Chodvadiya Ashish , Luo Jingjing 
Published: November 2023

Abstract
In recent years, journal bearings have been replacing roller bearings in wind turbine gearboxes, as they are believed to provide higher reliability compared with roller bearings. However, replacing roller bearings with journal bearings can drastically change the gearbox dynamics. Journal bearings have complex dynamics at different operating speeds, and, as a wind turbine operates at various speeds, it is vital to analyze the gearbox dynamics for the entire speed range. This contribution presents the dynamic response of a wind turbine gearbox when the roller bearings of the high-speed shaft are replaced with journal bearings. This is done by performing a comparative case study using a detailed multibody simulation (MBS) model of a 5 MW reference wind turbine drivetrain. A dynamic model of the journal bearings, developed in Simulink, is dynamically coupled with the 5 MW drivetrain MBS model using co-simulation. The simulation results for the gearbox vibration as well as gear forces are compared with the simulation results of the drivetrain model with roller bearings. The findings from this work will help in clarifying the advantages (or disadvantages) of using journal bearings instead of roller bearings in wind turbine gearboxes.
Open Source High Fidelity Modeling of a Type-5 Wind Turbine Drivetrain
Authors: Hussain Tanveer , Gallego-Calderon Juan , Shafiul Alam S M 
Published: November 2023

Abstract
The increasing integration of renewable energy resources in evolving bulk power system (BPS) is impacting the system inertia. Type-5 wind turbine generation has the potential to behave like a traditional synchronous generator and can help mitigate the impact on system inertia. A hydraulic torque converter (TC) and gearbox with torque limiting feature are integral parts of a Type-5 wind turbine unit. A high fidelity model of Type-5 wind turbine drivetrain is not openly and widely available for grid integration and transient stability studies. This hinders appropriate assessment of Type-5 wind power plant’s contribution to bulk grid resilience. This work develops and validates a TC model based on those generally used in automobile’s transmission system. Moreover, the concept of torsional coupling is leveraged to integrate the TC and gearbox system dynamics. The entire integrated model will be open sourced and publicly available for grid integration studies.
Impact of probe volume and peak detection methods on lidar rotor effective wind speed and turbulence intensity estimations
Authors: Costa F , Peña A , Pettas V , Cheng P 
Published: November 2023

Abstract
Lidar simulation techniques are a suitable and increasingly reliable alternative for testing lidar measuring strategies and illustrating their response when combined with modelled wind fields. In this work, two simulation tools are combined to assess the uncertainty in the derivation of the rotor effective wind speed and the wind speed variance from a forward-looking nacelle-mounted continuous wave lidar wind speed estimations. These uncertainties are analysed for a variety of atmospheric turbulence levels and lidar measuring strategies. A synthetic turbulence generator is used to create the reference wind fields. Subsequently, a lidar simulator operated in a continuous-wave mode is used to scan the synthetic wind fields and perform a sensitivity analysis by comparing first- and second-order statistics against reference values. The lidar simulator is enhanced with three Doppler peak detection methods, namely the maximum, the median and the centroid, to extract radial wind speeds from the velocities found within the probe volume. The results show that probe volume and peak detection methods influence the uncertainty of the wind speed variance. The uncertainty in time-averaged and instantaneous rotor effective wind speed estimations is not sensitive to the lidar spatial averaging or peak detection methods investigated. Finally, we saw that the turbulence intensity influences the derived lidar quantities and is the main driver of the variations in rotor effective wind speed uncertainty estimations.
Machine learning for predicting offshore vertical wind profiles
Authors: Rouholahnejad Farkhondeh , Santos Pedro , Hung Lin-Ya , Gottschall Julia 
Published: November 2023

Abstract
The accurate characterization of the vertical wind profile over the sea that covers the rotor swept area of modern wind turbines is a key challenge for wind energy yield calculations. Since offshore wind measurements are scarce, early-phase projects tend to use numerical model outputs before planning a dedicated measurement campaign. This study aims to develop and validate a machine-learning model that can assimilate wind parameters measured at the first level of the meteorological masts as input and provide a wind speed profile covering the rotor swept area of modern turbines that is more accurate than numerical weather prediction models. The methodology is based on a random forest model implemented in the python package Scikit-Learn. Three offshore sites in the North Sea have been selected for this study, namely FINO3, IJmuiden and Nordsee Ost’s (NSO) met mast, which are 100 to 350 km apart. Each site has an instrumented 100-m meteorological mast along with a Doppler wind lidar measuring up to 300 m. The baseline selected for comparison was the Weather Research and Forecast (WRF) model. To assess the accuracy of the random forest model two models were trained at IJmuiden and FINO3 and tested at all three locations. Hence, we examine the model performance at the site of training, the so-called same site approach, as well as new sites, the so-called round robin approach. The same site approach quantifies the model consistency, while the round robin shows the degree of spatial robustness. The results show that the model is consistent, where the model trained and tested at FINO3 showed a mean absolute error (MAE) reduction of 68% compared to WRF. This model is also robust, when applied at IJmuiden, 350 km away with a MAE of 1.2 m/s, 8% improved compared to WRF outputs. This study therefore shows the potential to implement machine-learning methods in the prediction of vertical wind speed profiles over the sea. One potential application for the presented methodology is the extension of wind profiles measured by floating lidar systems to higher heights, where current wind lidar products have low availability and higher associated uncertainties, when measuring at a higher height.
Standalone, Descriptive, and Predictive Digital Twin of an Onshore Wind Farm in Complex Terrain
Authors: Stadtmann Florian , Rasheed Adil , Rasmussen Tore 
Published: November 2023

Abstract
In this work, a digital twin with standalone, descriptive, and predictive capabilities is created for an existing onshore wind farm located in complex terrain. A standalone digital twin is implemented with a virtual-reality-enabled 3D interface using openly available data on the turbines and their environment. Real SCADA data from the wind farm are being used to elevate the digital twin to the descriptive level. The data are complemented with weather forecasts from a microscale model nested into Scandinavian meteorological forecasts, and wind resources are visualized inside the human-machine interface. Finally, the weather data are used to infer predictions on the hourly power production of each turbine and the whole wind farm with a 61 hours forecasting horizon. The digital twin provides a data platform and interface for power predictions with a visual explanation of the prediction, and it serves as a basis for future work on digital twins.
Yaw control strategies for 20 MW multi-rotor systems
Authors: Warner Markus , Eichelmann Tobias , Anselm Rudolf , Störtenbecker Sven , Dalhoff Peter 
Published: November 2023

Abstract
In this paper, the control of an active yaw system for a 20 MW multi-rotor wind turbine system (MRS) is considered. The MRS under investigation consists of five 4 MW turbines in two rows, which are connected to the tower via a space frame. A central yaw bearing at the height of the lower rotors is provided for active yaw. The paper aims to show that active aerodynamic yaw is possible by changing the thrust of certain rotors and should be considered for further research in the field of yawing of an MRS. Two different simulation environments are used in the paper. The MRS is modeled and simulated in Matlab/Simulink. Simulink’s own control modules are used as controllers. In the other simulation approach, the same MRS is modeled and simulated in Bladed and controlled with an external controller based on C++. The use of Bladed and Matlab/Simulink enables the plausibility and verification of the results. Matlab/Simulink is faster based of its simpler models but Bladed is more sophisticated. This paper also briefly presents the state of the art for yaw systems and yaw control of conventional single rotor wind turbines and initial research literature on yaw control of MRS.
A comparative study of laser-arc hybrid welding with arc welding for fabrication of offshore substructures
Authors: Bunaziv I , Ren X , Olden V 
Published: November 2023

Abstract
Laser-arc hybrid welding (LAHW) is an efficient and promising joining method for offshore structures made from metallic alloys. Under a high-power laser output, a keyhole is formed that efficiently melts a metal and provides high penetration depths compared to shallow and wide welds made by conventional arc welding, thus it requires much less time for production. A significant reduction in welding time leads to a substantial reduction of welding consumables and electricity use. Higher gap bridging ability can be achieved and tolerances for plate preparation is reduced when an arc is added to a laser beam. This work explicitly presents and compares different welding methods and their efficiency in application for offshore windmill substructures. According to a preliminary calculation, LAHW may reduce welding time by 10–20 times depending on process parameters and up to 15 times lower consumables usage. It was identified that the highest costs in welding is the filler wire followed by a shielding gas and electricity. This leads to high efficiency of LAHW in term of sustainability and reduction of CO2 emissions in general compared to well-established arc welding. However, the narrow and deep welds made by LAHW may suffer from high hardness in the root area, inhomogeneous filler metal mixing, which may lead to poor microstructure, cracking and porosity. This requires an extensive research work on the process optimization and understanding the underlying physics to provide sound welds which must comply with the international standards.
Effect of body motion on the wave loads computed with CFD on the INO-WINDMOOR floater
Authors: Califano A , Berthelsen P A , Magalhaes Duque Da Fonseca N M 
Published: November 2023

Abstract
CFD simulations were carried out on the 1:40 model of the INO WINDMOOR floater in regular waves to extract hydrodynamic loads, both on the structure, the single columns and sections from each column. Three different approaches for the platform motion were used, (i) fixed, i.e., restrained from motion, (ii) prescribed, i.e., forcing the floater to follow the motion recorded during model tests and (iii) 6 DOF, i.e., allowing the floater to move according to external forces from waves and anchor lines. The obtained results show the effect of the free surface on the local drag forces at sections with different submergences, which are important to include when modelling the motion with simplified methods based on pre-computed force coefficients. A comparison of the surge force shows that the amplitudes of the loads obtained with moving platform are reduced compared to the corresponding fixed case. The mean total surge force computed on the single columns and the whole platform show small quantitative differences between the different methods. The motion responses of the platform for surge and heave obtained with CFD are in fair agreement with the experiments.