bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantum fidelity and Von Neumann entropy of a Bose-Fermi mixture in 1D double well potential
Authors: Avella R , Rubio JP , Grajales D 
Published: May 2024

Abstract
The time evolution of probability density, the ground-state fidelity and the entanglement of a Bose-Fermi mixture in a 1D double well potential, are studied through the two-mode approximation. We found that the behavior of the quantum return probability shows three distinct regions. The first region is characterized by a complete miscibility, and correlated tunneling of bosons and fermion. The second region is characterized by correlated sequential tunneling and in the last region we found an increase in the tunneling frequency of the two species. Through the Von Neumann entropy, we found that the boson-fermion coupling allows a maximum entanglement of quantum correlations of bosons and fermions in the same value. Finally, Considering variations in the interaction between pairs of fermions λ

FF
, pairs of bosons λ

BB
, and variations in the interaction between particles of different species λ

BF
, we calculated the fidelity in the λ

FF
− λ

BF
and λ

BB
− λ

BF
planes and we found that the drop of the two fidelities becomes deeper and deeper as the boson-fermion interaction decreases.
Exact solution of the propagation of ON-OFF signals by dispersive waves
Authors: Yamamoto Ken 
Published: May 2024

Abstract
The propagation of ON-OFF signals with dispersive waves is examined in this study. An integral-form exact solution for a simple ON-OFF switching event is derived, which holds for any dispersion relation. The integral can be exactly calculated for two types of dispersion relations. Further, the analysis of these solutions shows that the ON-OFF signal propagates with the group velocity and that the boundary thickness of the signal increases with time, typically at a rate proportional to the square root of time, owing to dispersion. Additionally, an approximate solution for a general dispersion relation is derived, and for a higher-complexity ON-OFF switching pattern is constructed.
Design of ultra-thin multi-band sub-terahertz metamaterial absorber using three concentric ring resonators with same opening direction
Authors: Zhao Qian , Qin Xuefeng , Xu Chongyang , Zhou Haiquan , Wang Ben-Xin 
Published: May 2024

Abstract
In this paper, an ultra-thin sub-terahertz multi-band terahertz metamaterial absorber is proposed, its cell consists of three concentric ring resonators with the same opening direction, which can realize three discrete absorption peaks in the sub-terahertz frequency domain. The absorption peaks are mainly formed when the three open circular resonators interact with each other, and the superposition of the three discrete peaks creates a three-band absorption. The physical mechanisms of three-band absorption are illustrated by the electric fields and surface current distributions of three absorption peaks. Adjustment of the absorption effect could be obtained by altering the dimensions of the cleft circular resonator. By fixing the dimensions and changing the opening direction, these resonators will couple to each other and play an important role in regulating the frequency, intensity, and number of absorption peaks. Moreover, the multi-band metamaterial structure could be combined with vanadium dioxide, a phase change material, to actively modulate the absorption. In addition, the three-band metamaterial absorber has the characteristics of polarization-sensitive and wide-angle, which has extensive applications in the domains of security detection, biomedicine and communication.
Development of functionally gradient Cu-Fe based sintered brake pad materials
Authors: Kasi Rajesh Kannan , Murugesan Nithin Kumaar , Jeyakanapathy Aishwarya , Ramalingam Vaira Vignesh , Myilsamy Govindaraju 
Published: May 2024

Abstract
The world is seeking a sustainable co-existence with nature to preserve the balance of our ecosystem. This has opened a wider market for green and renewable forms of energy to realize the energy requirements of global countries. Among the various renewable energy sources, harnessing the kinetic energy of the wind through a turbine to generate electricity has seen an ardent growth. Wind turbines, in general, function between 2 m s−1 and 25 m s−1 wind speed. When the winds cross the cut-out speed (25 m s−1) or during the maintenance of wind turbine components, the brakes are implemented. The primary aerodynamic and secondary mechanical brakes comprise the wind turbine braking system. The mechanical brake pads are fixed to the brake caliper. On braking, the brake caliper pushes the brake pads against the brake disc. This recurring action gradually wears the brake material. The presence of ceramic particles in the traditionally used bulk composite pads imparts poor joint properties between the brake pad and caliper. These mandate frequent replacement of the brake pads. The current research work developed a functionally gradient brake pad through the powder metallurgy technique. The microstructure, microhardness, and tribological properties of the fabricated brake pads are tested and analyzed. Microstructural analysis revealed a homogeneous distribution of the reinforcements in the metal matrix. COF was observed to be within the desired range of between 0.3 and 0.4. The brake pad exhibited a combination of adhesive-abrasive-oxidative wear.
Planck constraints on cosmic birefringence and its cross-correlation with the CMB
Authors: Zagatti G. , Bortolami M. , Gruppuso A. , Natoli P. , Pagano L. , Fabbian G. 
Published: May 2024

AbstractCosmic birefringence is the in-vacuo, frequency independent rotation of the polarization plane of linearly polarized radiation, induced by a parity-violating term in the electromagnetic Lagrangian. We implement a harmonic estimator for the birefringence field that only relies on the CMB E to B mode cross-correlation, thus suppressing the effect of cosmic variance from the temperature field. We derive constraints fromPlanckpublic releases 3 and 4, revealing a cosmic birefringence power spectrum consistent with zero at about 2σup to multipoleL= 1500. Moreover, we find that the cross-correlations of cosmic birefringence with the CMB T-, E- and B-fields are also well compatible with null. The latter two cross-correlations are provided here for the first time up toL= 1500.
Using axion miniclusters to disentangle the axion-photon coupling and the dark matter density
Authors: Dandoy Virgile , Jaeckel Joerg , Montoya Valentina 
Published: May 2024

Abstract
Dark matter direct (and indirect) detection experiments usually can only determine a specific combination of a power of the coupling and the dark matter density. This is also true for axion haloscopes which are sensitive to the product g
2

aγγρ
DM, the combination of axion-photon coupling squared and the dark matter density. In this note we show, that in the lucky case when we intersect with a so-called axion minicluster of a suitable size, we can utilize the spectral information available in haloscopes to determine the gravitational potential of the minicluster. We can then use this to measure separately the coupling and the density of the minicluster.
Notes on emergent conformal symmetry for black holes
Authors: Xue Yesheng , Jiang Jie , Zhang Ming 
Published: May 2024

Abstract
We examine the motion of the massless scalar field and nearly bound null geodesics in the near-ring region of a black hole, which may possess either acceleration or a gravitomagnetic mass. Around such black holes, the photon ring deviates from the equatorial plane. In the large angular momentum limit, we demonstrate that the massless scalar field exhibits an emergent conformal symmetry in this near-ring region. Additionally, in the nearly bound limit, we observe the emergence of a conformal symmetry for the null geodesics that constitute the photon ring in the black hole image. These findings suggest that the hidden conformal symmetry, associated with the Lie algebra 𝔰𝔩(2, ℝ), persists even for black holes lacking north-south reflection symmetry, thereby broadening the foundation of photon ring holography. Finally, we show that the conformal symmetry also emerges for nearly bound timelike geodesics and scalar fields in proximity to the particle ring, and with specific mass around a Schwarzschild black hole.
Symmetry breaking due to multi-angle matter-neutrino resonance in neutron star merger remnants
Authors: Padilla-Gay Ian , Shalgar Shashank , Tamborra Irene 
Published: May 2024

Abstract
Neutron star merger remnants are unique sites for exploring neutrino flavor conversion in dense media. Because of the natural excess of ν̅e
over νe
, the neutrino-neutrino potential can cancel the matter potential, giving rise to matter-neutrino resonant flavor conversion. Under the assumption of two (anti)neutrino flavors and spatial homogeneity, we solve the neutrino quantum kinetic equations to investigate the occurrence of the matter-neutrino resonance within a multi-angle framework. We find that isotropy is broken spontaneously, regardless of the mass ordering. Relying on a hydrodynamical simulation of a binary neutron star merger remnant with a black hole of 3 M
⊙ and an accretion torus of 0.3 M
⊙, we find that complete flavor conversion caused by the matter-neutrino resonance is unlikely, although the matter and neutrino potentials cancel at various locations above the disk. Importantly, the matter-neutrino resonant flavor conversion crucially depends on the shape of the neutrino angular distributions. Our findings suggest that an accurate modeling of the neutrino angular distributions is necessary to understand flavor conversion physics in merger remnants, its implications on the disk physics and synthesis of the elements heavier than iron.
Improving data sharing in practice – power curve benchmarking case study
Authors: Barber Sarah , Ding Yu 
Published: May 2024

Abstract
In this work, a data sharing case study is presented, aiming to investigate and demonstrate how data sharing can be improved in practice in the wind energy sector. The case study is part of the WeDoWind framework, which creates tangible incentives to motivate different types of people to actually share data in practice. For this, a WeDoWind “challenge” on the topic of wind turbine power curve benchmarking is created and implemented within the framework. The results allow five different data-driven power curve prediction methods to be compared. The best method reduces the model error by as much as 70% in terms of mean absolute error and 45% in terms of root mean squared error compared to the standard industry method of binning. The results of a survey filled out by the participants show that data sharing could be improved compared to previous WeDoWind case studies, by providing more clear comparison and evaluation criteria, as well as by better integrating students into the WeDoWind framework. Overall, we find that “challenge”-based collaborations can help the industry become more innovative, by providing a motivation and basis for sharing data, as well as for comparing and benchmarking different methods. Finally, our experience in doing this as part of the present work allows us to make some suggestions for improving data sharing in practice.
Challenges on prognostics and health management for wind turbine components
Authors: Cuesta Jokin , Leturiondo Urko , Vidal Yolanda , Pozo Francesc 
Published: May 2024

Abstract
This paper explores the applicability of prognostics and health management (PHM) for wind turbines (WTs), presenting the PHM approach along with challenges and opportunities in the context of WT components. First, the PHM framework is introduced, consisting of three blocks: observation, analysis, and action. Critical components and failure modes for WTs are identified, and data acquisition strategies using supervisory control and data adquisition (SCADA) and condition monitoring (CM) data are discussed. Prognostics, specifically remaining useful life (RUL) estimation, employs physics model-based, data-driven, and hybrid models. Finally, challenges and opportunities related to data, analysis and CM, and developing RUL prediction models have been found. Data challenges include data standardization, limited public datasets, and data quality issues. Analysis and CM challenges address new sensorless and non-intrusive techniques, as well as the fusion of data sources. Prognostics model challenges involve uncertainty management, interpretability issues, and the need for online updates. Addressing challenges requires incorporating physical knowledge, utilizing transfer learning, and improving online RUL prediction methods.
Offshore field experimentation for novel hybrid condition monitoring approaches
Authors: Kestel Kayacan , Jamil Faras , Jo Matthys Jens , Vratsinis Konstantinos , Sterckx Jonathan , Marini Rebeca , Peeters Cédric , Helsen Jan 
Published: May 2024

Abstract
This study details the development of a fully automated pipeline for the condition monitoring of wind turbine drive trains. Vibration data is collected using hardware designed and manufactured in-house and used directly to monitor the condition of the drive trains. The complex nature of wind turbine vibration signals, due to the large number of components and highly variable operating conditions, makes drive train condition monitoring a challenging task. This paper details the full data measurement and analysis flow from sensor to insights and proposes a hybrid automated pipeline with signal processing and data-driven techniques to address the complexity of dealing with wind turbine vibration data. The vibration signals are directly employed to estimate the wind turbine’s instantaneous angular speed to compensate for any rotation speed fluctuations. Pre-processing is performed on the speed-independent signals to evaluate condition indicators in both the time and spectral domain for the vibration signals and their envelopes. Machine learning is then employed to distinguish the healthy state of the machine from a faulty one using the computed condition indicators. Besides the scalar indicators, also two-dimensional vibration decompositions such as the cyclic spectral correlation maps are used as inputs to the machine learning pipeline. This comprehensive and automated approach ensures both an early and reliable fault detection. Experimental results demonstrate that the fully automated hybrid pipeline can effectively be used for fleet-based health tracking of offshore wind turbine drivetrains.
Development and verification of a discrete event simulation tool for high-fidelity modelling of offshore wind and solar farm decommissioning campaigns
Authors: Mancini Simone , Bloothoofd Jesse , Dighe Vinit , van der Mijle Meijer Harald 
Published: May 2024

Abstract
The number of offshore wind turbines to be decommissioned is expected to grow in the next decade but some of the oldest wind farms in the North Sea region are already approaching the end of their service lives. This means that several detailed decommissioning plans will need to be prepared in the coming 2-5 years. So far, only small-scale wind farms consisting of relatively small turbines located in shallow, near-shore, or confined waters have been decommissioned. The limited experience and data available yield high uncertainty in the estimation of costs, duration, and environmental footprint of upcoming offshore wind farm decommissioning campaigns. High-fidelity logistic simulation tools as well as high-level cost models are both needed to support end-of-life decision-making. While several holistic cost models have been proposed, the literature lacks high-fidelity models to support the detailed planning and execution of offshore wind farm decommissioning projects. Given that offshore operations are the greatest source of costs, emissions, and safety risks in decommissioning campaigns, these require special attention when seeking optimization opportunities. In this work, a high-fidelity logistic simulation module for the decommissioning of offshore wind and solar farms has been developed within the discrete event simulation platform UWiSE. The new UWiSE Decommission module enables detailed assessment of alternative decommissioning scenarios taking into account offshore operation complexities like weather and resource dependencies, which are not included or heavily approximated in holistic cost models. The new tool has been verified against publicly available analytical cost model results from recent literature. A short assessment of the impact of weather delays on cost and duration estimates for the considered offshore wind farm decommissioning campaign has also been performed as an example of how UWiSE Decommission may bring value to the planning of offshore decommissioning projects.
Full scale testing of fatigue resistant composite joints for offshore wind Jacket and Floating structures
Authors: Pavlovic M , Koetsier M , Yang J , Mylonopoulos V , Wolters M , Segeren M , Van Wittenberghe J , Thibaux P , Vanderschueren M 
Published: May 2024

Abstract
Complex welds in the joint region reduce the fatigue resistance of structural joints of circular hollow sections with factors that results in increased wall thicknesses of the tubes and overspending of steel in the multi-membered part of the jacket and floating support structures for offshore wind turbines. The wrapped composite joint is a breakthrough technology utilising bonding and fatigue resistant composite material to connect steel tubular members instead of welding. The main technical advantage is that the superior fatigue life of wrapped composite joints. Full-scale wrapped composite joint is tested by cyclic out-of-plane bending loading in resonance-based Cronos testing rig at OCAS N.V. in Belgium. Results reveal exceptional fatigue life of wrapped joints to combined loading when compared to welded joints, showcasing a potential that can radically reduce steel use for offshore structures.
Incorporating Electricity Prices in Wind Turbine Design: Introducing the AEV Metric
Authors: Bechmann A , Barlas T , Madsen H A 
Published: May 2024

Abstract
This paper addresses the challenge of incorporating electricity prices into wind turbine design methods and shows how price volatility drives wind turbines towards larger rotors and lower specific power. Since wind speed and electricity prices fluctuate, current efforts to estimate a wind turbine’s revenue are based on time-series approaches. However, this paper presents a new way of accounting for price volatility based on wind distributions, which is computationally cheap and easily integrates with current wind turbine and farm design methods and tools. The new method demonstrates that a traditional wind turbine can lose more than 15% of its revenue in open energy markets like Denmark due to price volatility. Designing turbines with lower specific power can substantially increase revenue by producing more energy at low wind speeds with higher energy demand and electricity prices.
Methodology to assess scour development around complex structures
Authors: Sarmiento J. , Fernández S. , Guanche R. 
Published: May 2024

Abstract
Accurate prediction of scour evolution around fixed offshore foundations is a key parameter for selecting the most appropriate scour mitigation strategy. Various formulations can be used to estimate scour around monopiles. However, non-specific formulations have been developed for more complex foundations. In the case of jacketed offshore substations (OSS), the geometry can be one of the most complex. This paper describes a hybrid methodology (numerical model simulations, semi-empirical approaches and physical experiments) to estimate the scour evolution around OSS. The application of this methodology allows the selection of the most appropriate mitigation strategy from an early stage of the project to the final decision. The methodology is accompanied by some examples. In general, the results obtained from the semi-empirical approaches show quite good agreement with the measurements from the physical experiments. Nevertheless, considering the complex geometry of the OSS and the potential non-linearities associated with the platform geometry, physical experiments are required to ensure the correct estimation of the maximum scour (local and global).
Designing Large Segmented Flexible Conical Plain Bearings as Wind Turbine Main Bearings
Authors: Jakobs T , Jacobs G , Rolink A , Euler J , Hollas C , Röder J 
Published: May 2024

Abstract
Main bearings are failure-prone components in wind turbines, significantly increasing the LCOE of wind energy. Therefore, segmented plain bearings are being discussed as replacement for the currently used rolling bearings. Segmented plain bearings allow an up-tower replacement of faulty segments without the need to dismantle the WT drivetrain, as is required for rolling bearing replacements. One such bearing is the segmented, flexible, conical “FlexPad” plain bearing as alternative to existing double row tapered roller bearings. Designing the FlexPad bearing manually is very complex and thus time-consuming. Hence, during the research project a new holistic design method for large and highly loaded, conical plain bearings was developed. To prove the suitability of the method, two bearing prototypes were built and tested. The prototype, designed with the new method, outperformed the first, manually designed bearing, in terms of the design objectives. Most importantly, the friction losses were reduced by 32.1%. The project results show that the new method is able to efficiently design safely operating FlexPad bearing variants for wind turbines.
Phase-field simulation of the effect of grain boundary on fission gas migration in UO2 fuel
Authors: Liu Dongkun , Wang Qingyu , Zhang Tian 
Published: May 2024

Abstract
Grain boundaries are widely recognized as line defect sinks. During reactor operation, vacancies and fission gas atoms within UO2 fuel grains migrate to the grain boundaries, forming bubbles at these locations. In order to better understand the effect of grain boundaries on the migration of fission gas atoms, this study employed a phase-field model to simulate the nucleation and growth process of fission gas bubbles within the UO2 fuel grains and in the vicinity of grain boundaries. This study also investigated the degree to which grain boundaries affect fission gas atoms under different temperature conditions. The results indicated that in models containing grain boundaries, the nucleation of fission gas bubbles occurred earlier, as compared to models without grain boundaries. A noticeable bubble denuded zone was also observed adjacent to grain boundary interfaces. Furthermore, with increasing temperature, the bubble denuded zone becomes thicker. The effects of irradiation, vacancy diffusion, Ostwald ripening, as well as grain boundary trapping were discussed.