bluuebunny/crossref_metadata_2025 huggingface dataset:
Active fluctuations of axoneme oscillations scale with number of dynein motors
Authors: Sharma Abhimanyu , Friedrich Benjamin M. , Geyer Veikko F.
Published: November 2024

Fluxes of energy generate active forces in living matter, yet also active fluctuations. As a canonical example, collections of molecular motors exhibit spontaneous oscillations with frequency jitter caused by nonequilibrium phase fluctuations. We investigate phase fluctuations in reactivated
Chlamydomonas reinhardtii
axonemes, which are accessible to direct manipulation. We quantify the precision of axonemal oscillations after controlled chemical removal of dynein motors, providing an experimental test for the theory prediction that the quality factor of motor oscillations should increase with motor number. Our quantification reveals specialized roles of inner and outer arm dynein motors. This supports a model in which inner dyneins serve as master pace-makers, to which outer arm dyneins become entrained, consistent with recent insight provided by structural biology.
Lithium isotope evidence for a plumeworld ocean in the aftermath of the Marinoan snowball Earth
Authors: Gan Tian , Tian Meng , Wang Xi-Kai , Wang Shijie , Liu Xiao-Ming , Jiang Ganqing , C. Gill Benjamin , Nolan Morrison , Kaufman Alan J. , Luo Taiyi , Xiao Shuhai
Published: November 2024

The snowball Earth hypothesis predicts that continental chemical weathering diminished substantially during, but rebounded strongly after, the Marinoan ice age some 635 Mya. Defrosting the planet would result in a plume of fresh glacial meltwater with a different chemical composition from underlying hypersaline seawater, generating both vertical and lateral salinity gradients. Here, we test the plumeworld hypothesis using lithium isotope compositions in the Ediacaran Doushantuo cap dolostone that accumulated in the aftermath of the Marinoan snowball Earth along a proximal–distal (nearshore–offshore) transect in South China. Our data show an overall decreasing δ
7
Li trend with distance from the shoreline, consistent with the variable mixing of a meltwater plume with high δ
7
Li (due to incongruent silicate weathering on the continent) and hypersaline seawater with low δ
7
Li (due to synglacial distillation). The evolution of low δ
7
Li of synglacial seawater, as opposed to the modern oceans with high δ
7
Li, was likely driven by weak continental chemical weathering coupled with strong reverse weathering on the seafloor underneath silica-rich oceans. The spatial pattern of δ
7
Li is also consistent with the development and then collapse of the meltwater plume that occurred at the time scale of cap dolostone accumulation. Therefore, the δ
7
Li data are consistent with the plumeworld hypothesis, considerably reduced chemical weathering on the continent during the Marinoan snowball Earth, and enhanced reverse weathering on the seafloor of Precambrian oceans.
Identifying and controlling the order parameter for ultrafast photoinduced phase transitions in thermosalient materials
Authors: Ghasemlou Saba , Li Xinyue , Galimberti Daria R. , Nikitin Timur , Fausto Rui , Xu Jialiang , Holleman Steven , Rasing Theo , Cuppen Herma M.
Published: November 2024

The drastic shape deformation that accompanies the structural phase transition in thermosalient materials offers great potential for their applications as actuators and sensors. The microscopic origin of this fascinating effect has so far remained obscure, while for technological applications, it is important to learn how to drive transitions from one phase to another. Here, we present a combined computational and experimental study, in which we have successfully identified the order parameter for the thermosalient phase transition in the molecular crystal 2,7-di([1,1’-biphenyl]-4-yl)-fluorenone. Molecular dynamics simulations reveal that the transition barrier vanishes at the transition temperature. The simulations further show that two low-frequency vibrational–librational modes are directly related to the order parameter that describes this phase transition, which is supported by experimental Raman spectroscopy studies. By applying a computational THz pulse with the proper frequency and amplitude we predict that we can photoinduce this phase transition on a picosecond timescale.
Phase transition and metallization of semiconductor GeSe at high pressure
Authors: Luo Yuhua , Wu Min , Wu Ye , Wang Kai
Published: November 2024

Over the past few decades, semiconductor materials of the group IV–VI monochalcogenides have attracted considerable interest from researchers due to their rich structural characteristics and excellent physical properties. Among them, GeS, GeSe, SnS, and SnSe crystallize in an orthorhombic structure (Pbnm) at ambient conditions. It has been reported that GeS, SnS, and SnSe transform into a higher symmetry orthorhombic structure (Cmcm) at high pressure, while the phase transformation route of GeSe at high pressure remains controversial. As an IV–VI monochalcogenide, GeSe possesses excellent application prospects and has been extensively studied in the fields of optoelectronic and thermoelectric. Here we systematically investigate the structural behavior, optical and electrical properties of GeSe at high pressure. GeSe undergoes a phase transition from the Pbnm to Cmcm phase at 33.5 GPa, like isostructural GeS, SnS, and SnSe. The optical bandgap of GeSe decreases gradually as pressure increases and undergoes a semiconducting to metallic transition above 12 GPa. This study exhibits a high-pressure strategy for modulating structural behavior, optical and electrical properties of the group IV–VI monochalcogenides to expand its prospects in optoelectronic and thermoelectric properties.
Gecko-inspired adhesion enhanced by electroadhesive forces
Authors: Tan Lihaoya , Lee Loong Yi , Kulykov Alex , Rossiter Jonathan , Conn Andrew T
Published: November 2024

Soft robotic manipulators have been increasingly adopted over the last decade due to their passive conformation to the shapes of objects, which can reduce control complexity. The performance of these grippers can be improved using flexible adhesive skins that increase tactile gripping forces, which is particularly important when grasping delicate objects and flexible substrates that are otherwise difficult to manipulate. In this work, we investigate how passive gecko-inspired fibrillar adhesion can be augmented by actively controlled electroadhesion (EA). The passive gecko-inspired skin (GS) enables adhesion with no power consumption while EA is controlled with an applied voltage. We have shown how the microstructures in a gecko-inspired adhesive skin affect EA by using numerical simulation to quantify how they influence the localized EA field strength. The results show that the microstructures cause a highly non-uniform distribution of electric field strength generate and hence the EA force distribution is inhomogeneous. Overall, it was found that the dielectric properties of the gecko-inspired skin reduce the magnitude of field intensity on the adhesive contact surface by only 2.1% at 3 kV. It is experimentally determined that when compared with GS alone, EA with gecko-inspired skin increases the shear force by 66.8% and the normal force by 53.7% with an applied voltage of 4 kV. It is shown that the gecko skin’s adhesion force is enhanced by increased engagement of the fibrillar microstructure to object surfaces due to EA. The increased contact engagement is experimentally demonstrated using frustrated total internal reflection imaging. This work shows that electroadhesive-enhanced gecko-inspired skin generates a greater adhesive force than the sum of forces from the separate gecko-inspired skin and EA. In this way, electrically controllable and passive adhesion mechanisms can be combined to improve the handling of flexible and delicate objects with smooth or rough surfaces.
Ultrafast imaging of laser-induced modifications in planar targets via single-shot in-line holography
Authors: Altenkirch Richard , Peltz Christian , Böttcher Tom , Lochbrunner Stefan , Fennel Franziska , Fennel Thomas
Published: November 2024

We present a holographic single-shot coherent diffractive imaging method based on in-line holography that allows the ultrafast characterization of 2D transmission maps of semi-transparent planar targets such as foils in amplitude and phase. Holographic information is obtained from the interference of the transmitted primary beam with the fields scattered from the modified or unknown target regions. A specialized iterative phase retrieval is used to incorporate the holographic nature of the approach and to accelerate and improve convergence. The achievable quality and reproducibility of the reconstructed transmission maps as well as optimal setup parameters are investigated using realistic pre-characterized reference targets. We used non-circular laser-induced hole structures in 30 nm thin gold foils that represent the final state of a laser modification and show that the far field error of the reconstructed diffraction images can be used to estimate and optimize the reconstruction quality in the object plane in order to obtain accurate and reproducible transmission maps. Our results mark the important first step towards the full spatio-temporal analysis of all stages of laser material modification or laser ablation in two-color pump probe experiments, including plasma formation, equilibration, and expansion.
Integrating theoretical and experimental approaches to unveil the mechanical properties of CuSbSe2 thin films
Authors: Surucu Ozge , Gencer Aysenur , Usanmaz Demet , Parlak Mehmet , Surucu Gokhan
Published: November 2024

An exhaustive investigation of the mechanical characteristics of CuSbSe2 thin films is conducted in this study by combining experimental nanoindentation methods with theoretical simulations. The Ab-initio Molecular Dynamics (AIMD) calculations are performed with the machine learning (ML) force fields. By employing the Vienna Ab-initio Simulation Package (VASP) based on Density Functional Theory (DFT), theoretical inquiries are carried out to identify crucial parameters, such as bonding characteristics, elastic constants, hardness, bulk modulus, shear modulus, Young’s modulus, and Poisson’s ratio. Experimental validation is conducted using nanoindentation to investigate load-dependent hardness and Young’s modulus in a manner that closely matches the theorized predictions. The anomalies between experimental and theoretical outcomes are ascribed to anisotropic behavior and grain boundaries. Furthermore, an investigation is conducted into the directional dependence of sound wave velocities in the CuSbSe2 films, leading to the revelation of intricate elastic property details. By employing an integrated theoretical-experimental approach, the present attempt not only increases the knowledge concerning CuSbSe2 films but also fortifies the relationship between theory and experiment, thereby bolstering the dependability of our results. The insights provided as a result of this paper facilitate the development of CuSbSe2 film applications in a variety of technological fields in the future.
Generation and enhancement of sum sideband in a magnon Kerr nonlinearity assisted optomechanical system
Authors: Liao Qing-Hong , Tang Zhi-An , Ao Jia-Wen , Nie Wen-Jie , Song Meng-Lin
Published: November 2024

A theoretical scheme to enhance the sum sideband generation (SSG) via magnon Kerr nonlinearity assisted optomechanical system is proposed. In this scheme, the yttrium iron garnet sphere is placed within the cavity system and the frequency components are generated at the sum sideband through optomechanical nonlinear interaction and cavity-magnon linear coupling interaction. The results show that the efficiency of SSG can be enhanced by several orders of magnitude, and the gain in SSG efficiency also varies. The dependence of SSG on the system parameters, including the power of the control field, the frequency detuning of the probe fields and the coupling strengths between the optomechanical coupling and the cavity-magnon coupling is analyzed in detail. The change of SSG by varying the optomechanical coupling strength and cavity-magnon coupling strength is also investigated, and it is found that new matching conditions are generated. The enhanced SSG method may have potential application prospects in realizing the measurement of high-precision weak forces, quantum information processing and quantum-sensitive sensing.
Pressure-induced superconductivity and phase transition in PbSe and PbTe
Authors: Jiang 江 Yuyang 宇阳 , Pei 裴 Cuiying 翠颖 , Wang 王 Qi 琦 , Wu 吴 Juefei 珏霏 , Zhang 张 Lili 丽丽 , Xiong 熊 Chao 超 , Qi 齐 Yanpeng 彦鹏
Published: November 2024

The IV–VI semiconducting chalcogenides are a large material family with distinct physical behavior. Here, we systematically investigate the effect of pressure on the electronic and crystal structures of PbSe and PbTe by combining high-pressure electrical transport and synchrotron x-ray diffraction (XRD) measurements. The resistivity of PbSe and PbTe changes dramatically under high pressure and a non-monotonic evolution of ρ(T) is observed. Both PbSe and PbTe are found to undergo semiconductor–metal transition upon compression and show superconductivity under higher pressure. The structural evolutions from the

F
m

3
¯

m

to Pnma phase and then to the

P
m

3
¯

m

phase in PbSe are verified by the x-ray diffraction. The present findings reveal the internal correlation between the structural evolution and the physical properties in lead chalcogenides.
Ultrafast reconfigurable direct charge trapping devices based on few-layer MoS2
Authors: Gao 高 Hui 辉 , Liu 刘 Xuanye 轩冶 , Song 宋 Peng 鹏 , Wei 尉 Chijun 驰俊 , Jiazila 努 Nuertai 尔泰⋅加孜拉 , Sun 孙 Jiequn 杰群 , Wu 吴 Kang 康 , Guo 郭 Hui 辉 , Yang 杨 Haitao 海涛 , Bao 鲍 Lihong 丽宏 , Gao 高 Hong-Jun 鸿钧
Published: November 2024

Charge trapping devices incorporating 2D materials and high-κ dielectrics have emerged as promising candidates for compact, multifunctional memory devices compatible with silicon-based manufacturing processes. However, traditional charge trapping devices encounter bottlenecks including complex device structure and low operation speed. Here, we demonstrate an ultrafast reconfigurable direct charge trapping device utilizing only a 30 nm-thick Al2O3 trapping layer with a MoS2 channel, where charge traps reside within the Al2O3 bulk confirmed by transfer curves with different gate-voltage sweeping rates and photoluminescence (PL) spectra. The direct charging tapping device shows exceptional memory performance in both three-terminal and two-terminal operation modes characterized by ultrafast three-terminal operation speed (∼300 ns), an extremely low OFF current of 10−14 A, a high ON/OFF current ratio of up to 107, and stable retention and endurance properties. Furthermore, the device with a simple symmetrical structure exhibits V
D polarity-dependent reverse rectification behavior in the high resistance state (HRS), with a rectification ratio of 105. Additionally, utilizing the synergistic modulation of the conductance of the MoS2 channel by V
D and V
G, it achieves gate-tunable reverse rectifier and ternary logic capabilities.
Patient-specific visual neglect severity estimation for stroke patients with neglect using EEG
Authors: Kocanaogullari Deniz , Gall Richard , Mak Jennifer , Huang Xiaofei , Mullen Katie , Ostadabbas Sarah , Wittenberg George F , Grattan Emily S , Akcakaya Murat
Published: November 2024

Objective. We aim to assess the severity of spatial neglect (SN) through detailing patients’ field of view (FOV) using EEG. Spatial neglect, a prevalent neurological syndrome in stroke patients, typically results from unilateral brain injuries, leading to inattention to the contralesional space. Commonly used Neglect detection methods like the Behavioral Inattention Test—conventional lack the capability to assess the full extent and severity of neglect. Although the Catherine Bergego Scale provides valuable clinical information, it does not detail the specific FOV affected in neglect patients. Approach. Building on our previously developed EEG-based brain–computer interface system, AR-guided EEG-based neglect detection, assessment, and rehabilitation system (AREEN), we aim to map neglect severity across a patient’s FOV. We have demonstrated that AREEN can assess neglect severity in a patient-agnostic manner. However, its effectiveness in patient-specific scenarios, which is crucial for creating a generalizable plug-and-play system, remains unexplored. This paper introduces a novel EEG-based combined spatio-temporal network (ESTNet) that processes both time and frequency domain data to capture essential frequency band information associated with SN. We also propose a FOV correction system using Bayesian fusion, leveraging AREEN’s recorded response times for enhanced accuracy by addressing noisy labels within the dataset. Main results. Extensive testing of ESTNet on our proprietary dataset has demonstrated its superiority over benchmark methods, achieving 79.62% accuracy, 76.71% sensitivity, and 86.36% specificity. Additionally, we provide saliency maps to enhance model explainability and establish clinical correlations. Significance. These findings underscore ESTNet’s potential combined with Bayesian fusion-based FOV correction as an effective tool for generalized neglect assessment in clinical settings.
A universal target plate design scheme for stellarators: theoretical basis and its application to heat load control
Authors: Liu B. , Kawamura G. , Dai S.Y. , Xu Y. , Suzuki Y. , Shimizu A. , Frerichs H. , Feng Y.
Published: November 2024

This study introduces a novel divertor target design scheme for stellarators, grounded in mathematical treatments and tailored to control of toroidal heat load distributions. Initially, a differential equation characterizing toroidally uniform heat load distribution has been formulated in a two-dimensional (2D) slab configuration, and its analytic solution has been obtained. Subsequently, a numerical scheme has been developed to adapt the analytic solution into the 3D surface shape of stellarator target. The effectiveness of this design scheme has been validated through simulations of the Chinese First Quasi-axisymmetric Stellarator (CFQS) using a suite of codes including HINT, FLARE and EMC3-EIRENE, where a toroidally uniform heat load distribution has been achieved with an island configuration. Further, the effects of input parameters on the target shape and heat load distribution have been studied. The robustness of the designed target has been investigated by simulation results with varying magnetic island configurations, confirming that the toroidal uniformity of heat load distribution is insensitive to changes in island configurations. Moreover, the designed target has been assessed with gas puffing of neon, which shows that neon injections effectively reduce the heat loads without altering the toroidal uniformity of heat load distributions. The proposed scheme highlights the importance of theoretical and mathematical foundations of target design, offering an advantageous alternative/complement to traditional schemes.
Cost and Efficiency analysis of the Secondary electric machine in a CRAFT wind turbine
Authors: Robertsson A C , Nordin E , Simonsson I , Bernhoff H
Published: November 2024

Floating offshore wind turbines are ideal for deeper waters, providing access to stronger and more stable winds. The Counter-Rotating Axis Floating Tilting (CRAFT) turbine features a unique design with two counter-rotating turbines on a tilted vertical shaft and two independent electrical machines submerged below sea level. The primary generator, connected to both turbines, includes counter-rotation which doubles the relative torque, while the secondary machine controls the upper turbine.

This study examines the impact of primary and secondary machine efficiency on electricity generation. The findings indicate that the primary generator’s efficiency is crucial for system stability, whereas the secondary machine’s efficiency is less critical. Reducing the secondary machine’s efficiency from 97% to 83% resulted in a 0.1% reduction in annual electricity generation. Despite the asynchronous machine’s lower efficiency, it is the economically favorable choice as the secondary machine over its synchronous counterpart due to its reduced design complexity and lower magnet costs, leading to lower overall expenses.

Future research investigate how turbulent flow effects and airflow interactions between the turbines influences the model. Incorporating the cooling factor, a more comprehensive cost model and a refined dynamic stall model will also further improve the simulation’s accuracy and robustness.
IEA Wind Task 49: Reference Site Conditions for Floating Wind Arrays
Authors: Creane Shauna , Santos Pedro , Kölle Konstanze , Ecenarro Diaz-Tejeiro Laura , Zouaoui Aimen , Airoldi Davide , Bakhoday-Paskyabi Mostafa , Biglu Michael , Brown William , Frøyd Lars , Li Lin , Cheynet Etienne , Hagerman George , Hall Matthew , Kim Yong-Yook , Guo Larsén Xiaoli , Musialik Mateusz , Park Miho , Tronfeldt Sørensen Jacob , Tanemoto Jun , You Young-Jae
Published: November 2024

The commercial-scale deployment of floating offshore wind (FOW) projects is expected to take place in a diverse range of sites that may differ significantly from existing fixed-bottom projects. FOW farms are particularly sensitive to the water depth and the meteorological and oceanographic (metocean) and geotechnical conditions at the project site due to the wave-induced system motions and loads as well as the anchoring system constraints imposed by the seafloor conditions. Uncertainty around the site conditions will permeate through all aspects of project design, leading to suboptimal and overly conservative designs, increased costs, and adversely affected performance. As FOW expands into a global industry, metocean and geotechnical conditions will increasingly vary for projects located in different geographic regions or in far-from-shore, deep-water sites. This study represents the outputs of work package 1 of International Energy Agency Wind Task 49, which focuses on the integrated design of floating wind arrays. The primary goal of this study is to establish the type of parameters and constraints required to characterize FOW array reference sites; provide a realistic and publicly available set of reference site conditions to the FOW community as a baseline set of data for individual research projects; identify and categorize any critical gaps in the existing data or methodologies required to define reference site characteristics; and inform and support the design of reference FOW arrays. A building block concept was developed for synthesizing reference sites for the design of FOW arrays. The building blocks include three classes of site conditions focusing on the techno-economic design of FOW projects: metocean conditions, seabed conditions, and coastal infrastructure. All reference site data produced and collected in this study are publicly available.
Insights in wind field reconstruction from two nacelles’ LiDAR in the same offshore wind farm
Authors: Marini Rebeca , Vratsinis Konstantinos , Daems Pieter-Jan , Verstraeten Timothy , Helsen Jan
Published: November 2024

The global rise in offshore wind farms underscores the need to cut costs and optimise energy production. As turbines increase in size and wind farms become more concentrated, mitigating downstream wake effects is crucial for operational efficiency. LiDAR technology, offering advantages like eliminating the need for meteorology masts, has been extensively discussed in the literature. However, it indirectly measures wind parameters, relying on assumptions and embedded algorithms. Wind field reconstruction (WFR) methods empower users with more control over LiDAR measurements, allowing tailored flow assumptions and parameter estimation. Using LiDAR data from two sequential campaigns at a wind farm, our research analyses LiDAR performance validated with SCADA measurements and applies WFR for wind field parameters estimation. Comparative analyses of wind parameters from different sources, particularly downstream turbines, demonstrate the robustness of WFR. The reconstructed wind field is compared with SCADA data for a comprehensive assessment.
Daylight Considerations for Offshore Wind Operations and Maintenance
Authors: Donnelly Orla , Carroll James
Published: November 2024

The cost associated with operations and maintenance (O&M) for offshore wind is a cost that developers and operators are striving to reduce in order to reduce the overall Levelised Cost of Energy. Improving accessibility and increasing time based availability of wind turbines can guarantee these reductions. To increase time based availability , some wind farms utilise night shift work to reduce downtime for turbines. Previous studies revealed cost reductions using this method but are strictly based on North Sea wind farms. This paper investigates the impact daylight hours have on the O&M costs for an offshore wind farm depending on location. Using an O&M model, three maintenance strategies are simulated and their associated O&M costs are found: ‘Daylight Limited’, ‘Daylight Not Limited’ and ‘Night Shift’. Three case studies are chosen: North Sea, USA and Australia. The operational costs for the North Sea were reduced by £32.74/MWhr with the introduction of the night shift. With increased daylight, the US site saw a smaller reduction in operational costs of £3.48/MWhr using the night shift. However, the Australian site was negatively impacted when adopting a night shift strategy as operational costs increased by £3.19/MWhr. The study considers, if there are reductions in cost through night shift, is it worth the trade-of the industry makes for health and safety of technicians who work at night.
CFD analysis of droplet impact pressure for prediction of rain erosion of wind turbine blades
Authors: Edirisinghe Dylan S. , Zambrano M. Lilibeth A. , Tobin Edmond , Vashishtha Ashish
Published: November 2024

Rain erosion is a prominent issue in Offshore Wind Turbines (OWT) with wind farms experiencing heavy and frequent rainfall compared to onshore conditions. A simplified Springer model is used widely by industries to predict erosion initiation in composite materials and has been under various recent investigations to improve its predictability of rain erosion. However, the Springer model uses the modified water hammer equation to compute impact pressure, and it does not consider the impact of droplet sizes. This Computational Fluid Dynamic (CFD) study is motivated to develop an understanding of the effect of droplet sizes on impact pressure while discussing impact behaviour in detail. Simulations were conducted for droplet diameters ranging between 1 to 5 mm with an impact speed of 100 m/s. The results show that the water droplets slightly deform just before the impact, delaying the impact time due to the pressurised air layer in between the droplet and substrate. During this delay period, the impact pressure was significantly increased to reach the maximum impact pressure. Maximum impact pressure was found to increase with the droplet size, due to high air volume displacement whereas, this phenomenon is not accounted for in pressure estimation in the Springer model. In conclusion, the larger droplets were observed to impose higher pressure on the blade’s coating than the smaller droplets, which can lead to high erosion levels.
Experimental Investigation of Towing of a Semi-submersible Floating Offshore Wind Turbine
Authors: Yin Decao , Indergård Robert , Lie Halvor , Braaten Henning
Published: November 2024

The offshore floating wind energy sector is poised for exponential growth in the coming decades. A pivotal challenge within this context is the imperative to substantially decrease the levelized cost of energy (LCOE) to enhance competitiveness. A significant proportion of these LCOE costs are attributable to the towing operations entailed in both the installation of assembled floating wind turbines and the maintenance of major components.

Semi-submersibles, characterized by multiple columns and pontoons, represent the prevailing conceptual approach in the industry due to their versatility across varying water depths and their cost-effectiveness in terms of mooring and transportation. Towing model tests for the semi-submersible INO WINDMOOR floating wind turbine have been conducted in the Ocean Basin at SINTEF Ocean. The primary objective of these tests is to investigate critical aspects such as towing resistance and dynamic responses, including vortex-induced motion (VIM) and galloping.

This paper presents the experimental set-up and initial findings from the model tests. Through comparative data analysis of selected cases, an enhanced and insightful understanding of the intricate fuid-structure interactions is expected to be achieved. Additionally, it highlights the identification of knowledge gaps and research imperatives aimed at expanding the towing operational criteria, with the ultimate goal of reduction of installation and maintenance costs.
Design optimization of floating offshore wind farms using a steady state movement and flow model
Authors: Feng Ju , Pedersen Mads Mølgaard , Riva Riccardo , Bredmose Henrik , Santos Pedro
Published: November 2024

In this study, we demonstrate how to carry out the design optimization of floating offshore wind farms by considering the impacts brought by the movements of the floating wind turbines. A steady state movement and flow model is applied in the modelling process. This model is developed by building a turbine surrogate model for estimating the steady state movement and power production of floating wind turbines and incorporating it in an open-source static wind farm simulator, PyWake. Using this modelling methodology, layout optimization problems of floating offshore wind farms are solved by using algorithms like Random Search to maximize the energy yield while satisfying certain constraints. Case studies are carried out for two wind farms with met-ocean conditions from a real planned site in Scottland to show the potential of layout optimization for floating wind farms.
Comparison of classical and drone based hard-target methodologies applied to scanning lidar for offshore wind
Authors: Oldroyd A , Young M , Docherty M , Bost J , Redford S , Haize J , Royle J , Gottschall J
Published: November 2024

Hard target testing is a crucial part of the commissioning process of scanning lidar measurement systems. The correct alignment of the scan head and understanding of the pointing accuracy is crucial to reducing uncertainties in wind speed measurements by scanning lidar especially in dual-scanning configuration. This paper presents a comparison between traditional hard targeting technique and the use of drone based hard targets. A procedure is presented to minimise measurement error and hence increase confidence in the pointing accuracy.
Revenue assessment of damage aware wind farm control for secondary frequency regulation provision
Authors: Dupont K , Chapaloglou S , Cali Ü
Published: November 2024

In this paper, a case study of a wind power plant participating in the balancing market is presented and any potential revenue benefits are estimated. To make a representative performance assessment, an existing case for the frequency regulation market is selected, based on the pay-for-performance scheme of the US regional transmission operator Pennsylvania-New Jersey-Maryland (PJM). In this implementation, the wind power plant is being rewarded or penalized based on its signal-tracking capabilities, which are quantified by proper performance metrics. The fast response characteristics of the wind turbines allow for tracking even the faster automatic regulation signal (RegD from PJM). However, one of the significant challenges associated with providing such type of active power reference tracking on the wind farm scale is that different turbines have different responses and structural damage accumulation due to the local environmental conditions and the coupling due to wakes. The in-house developed, numerically efficient, wind farm simulation model “regfarm” is employed, allowing for a thorough analysis and revenue assessment under various operating regimes and weather conditions. Numerous time-domain simulations and historical pricing time series are used to quantify the expected revenue from market participation. Under the regulation market pay-for-performance compensation scheme, the simulated wind farm earned a lower revenue when compared to maximizing energy production. Depending on the configuration, the wind farm experiences between a 2.14% and a 2.38% decrease in revenue when providing 10% of the estimated available power to the regulation market. The wind farm is operated as both damage-ignorant and damage-aware, with no significant comparative loss in revenue when the damage distribution is considered.
Assessment of microplastics in the sediments around Hywind Scotland Offshore Wind Farm
Authors: Piarulli Stefania , Sørensen Lisbet , Kubowicz Stephan , Vrålstad Heléne K. , Mette Murvoll Kari , Booth Andy M.
Published: November 2024

Leading edge erosion of turbine blades is hypothesized to be a source of microplastic (MP; 1-5000 µm) emissions from offshore wind farms (OWFs) to the marine environment. Given the higher density of rotor blade coating and leading-edge protection (LEP) materials than seawater, released MP are expected to enter the surrounding waters and sink to the sediments, where the highest concentrations may be expected in the sediments in and around the OWF infrastructure. Here, we present a methodological approach for the quantification and characterisation of coating and LEP MPs (>300 µm) in sediments, applied to samples collected from 15 locations around the Hywind Scotland floating OWF. To validate the approach, reference materials were produced from the different coating layers and LEP material and used to generate library IR spectra and mass spectra so that such particles could be robustly identified if present in the sediment samples. The reference materials were also used to evaluate particle integrity and recovery across the sample preparation applied to real samples (ZnCl2 density separation, filtration). Results suggested the LEP material was unaffected by the sample processing, but fragmentation was observed for the two coating layers studied, leading to an increase in the number of particles and a decrease in weight due to loss of particles <300 µm. After isolation, particles were evaluated using microscopy and suspected MP particles were identified and subjected to a detailed chemical characterisation by Fourier transform infrared spectroscopy (FTIR). In the field samples, twenty particles were confirmed as MP, but none had polymer compositions matching the coatings and LEP materials, instead representing common thermoplastics in the form of flakes, films, fragments, and filaments.
Research on fall prevention and safety protection for electric power tower climbing operations based on the longhorn whisker algorithm
Authors: Zhan Peilin , Zeng Yonghao , Yu Shanhui
Published: November 2024

With the continuous development of the power industry, the safety of power tower climbing operations is increasingly valued. This study focuses on the anti-fall safety protection of electric power tower climbing operations and proposes a study on the anti-fall safety protection of electric power tower climbing operations based on the Longhorn whisker algorithm. Firstly, real-time image acquisition of the climbing operation site is carried out through the camera equipment carried by the drone, ensuring clear and comprehensive information on the working environment is obtained. Secondly, extract hazardous features in climbing operations, such as abnormal worker posture, tool detachment, etc. These features are important indicators of potential fall risks. Finally, a fall hazard detection model is constructed and optimized using the Longhorn Whisker algorithm to identify and warn of impending fall events, thereby providing timely safety protection for climbing operators. The experimental results show that this method has shown significant effectiveness in improving job safety, providing strong technical support for the safety protection of power tower climbing operations.
Model predictive power control for grid-tied T-type three-level quasi-Z-source inverter with low complexity
Authors: Liu Yangbo , Kang Longyun , Liu Lin , Zhu Chunsheng
Published: November 2024

The appealing design known as T-type three-level quasi-Z-source inverters (T2LQZSI) can function in both step-down and step-up modes. Model predictive control for converters has also received a lot of interest. This article suggests a low-complexity model predictive power control for T-type quasi-Z-source inverters with neutral-point voltage (NP-V) balance to address the shortcomings of conventional model predictive control and achieve improved performance. The resulting voltage is produced by using a variety of vectors. For NP-V balance, the tiny vector is employed. In addition, a strong optimum sector selection approach is suggested, which significantly lowers the processing complexity. Results from experiments show how effective and better the suggested technique is.
A short-term load forecasting method based on QRLSTM considering multiple factors analysis
Authors: Wu Huahua , Chen Wenjin , Zhang Si , Tang Lv , Liu Ang , Deng Shichang
Published: November 2024

Complex characteristics of power loads terribly affect the safety of the power grid. Thus, accurate short-term load forecasting is regarded as a solution to mitigate the effect of load complications. In this regard, this work is putting forward a Long Short-Term Memory Network Quantile Regression (LSTMQR) for power load, obtaining the probability density function (PDF). Firstly, the quantile of future power load was obtained using the LSTMQR model. The conditional quantile obtained by the LSTMQR model is used as the input of the Kernel Density Estimation model (KDE) to predict the future probability density distribution of short-term power load at different prediction times. Furthermore, an assessment method is proposed to quantify the effect of different factors on power load to improve prediction accuracy. Finally, a numerical simulation based on actual data in China is established to validate the effectiveness of the proposed forecasting algorithm, indicating the proposed forecasting algorithm can effectively evaluate the relationship between different factors and power load, and probability density prediction can accurately quantify the uncertainty of load information. The proposed algorithm results in a reduction of 37.6% in forecast error compared to the traditional forecasting algorithm.
The optimal design of airflow modes for double-layer solar air heater with perforated baffles
Authors: Liu Ying , Long Yanping
Published: November 2024

To further improve the thermal performance of SAH, two mathematical models of the double-layer solar air heater with perforated baffles (DSAH-PB) were established to analyze the optimal airflow modes. In Mode 1, the air flowed parallelly in the upper and lower channels; in Mode 2, the airflow in the upper channel was opposite to the airflow in the lower channel. Validation against reported data showed the models’ accuracy with a maximum relative deviation of less than 10%. Results indicated that Mode 2 achieved a collection efficiency 2.57∼4.28% higher than Mode 1, attributable to a thinner boundary layer and increased turbulence, enhancing the convective heat transfer coefficient. Comparative analysis revealed that the outlet temperatures in Mode 2’s upper and lower channels exceeded those in Mode 1 by 0.37∼ 3.67°C and 1.63∼7.48°C, respectively. Velocity distribution analysis confirmed the superior performance of Mode 2, with a more uniform velocity distribution and lower absorber plate temperature, contributing to improved thermal efficiency. The study underscored the importance of airflow distribution and channel design in optimizing SAH performance.
Evaluation and regulation methods for the utilization of Type-II oil reservoirs using ASP flooding
Authors: Yuan Yuan
Published: November 2024

Existing methods for calculating oil reservoir utilization in chemical flooding rely on the instantaneous water absorption profile, which fails to provide an accurate description of the actual utilization conditions of the reservoir, making it imperative to find a method that accurately reflects the reservoir utilization. Type-II oil reservoirs often exhibit significant vertical heterogeneity. During chemical flooding, the impacts of high-permeability layer utilization, low-permeability layer utilization, and the simultaneous utilization of both layers on recovery are to be explored. Therefore, it is important to investigate the recovery requirements for different types of reservoirs. This study explores the solutions for improved reservoir utilization as well as the evaluation and regulation methods for the utilization of secondary oil reservoirs using the Alkaline-Surfactant-Polymer (ASP) flooding, which is of great significance for the adjustment of ASP flooding, injection, and production of secondary oil reservoirs.
The passive recording of the click trains of a beluga whale (Delphinapterus leucas) and the subsequent creation of a bio-inspired echolocation model
Authors: Qing Xin , Wang Yuncong , Xia Zhi , Liu Songzuo , Mazhar Suleman , Zhao Yibo , Pu Wangyi , Qiao Gang
Published: November 2024

A beluga-like model of click train signal is developed by observing beluga’s sound recording. To reproduce the feature of the biosonar signal, this paper uses a signal extracting method with a correction factor of inter-click interval to acquire the parameter of click trains. The extracted clicks were analyzed in the time and frequency domain. Furthermore, a joint pulse-frequency representation was undertaken in order to provide a 2D energy distribution for an echolocation click train. The results from joint pulse-frequency representation indicate that click train can be adjusted its energy distribution by using a multi-component signal structure. To evaluate the capability of the click train to inform the whale of relevant target information perception for the click train, a finite element model is built to reproduce target discrimination by the bio-inspired click train. Numerical results indicate that the bio-inspired click train could enhance the echo-response by concentrating energy into the frequency bins for extracting target feature effectively. This proof-of-concept study suggests that the model of click train could be dynamically controlled to match the target properties, and show a promising way to use various types of echolocation click train to interrogate different features of the target by man-made sonar.
Indications of a changing winter through the lens of lake mixing in Earth’s largest freshwater system
Authors: Anderson Eric J , Tillotson Brooke , Stow Craig A
Published: November 2024

Global surface freshwater primarily resides in lakes, with the overwhelming majority found in Earth’s largest lakes, thus understanding potential climate change effects in these large lakes is critical. In dimictic lakes, climate change has extended the duration of summer thermal stratification and reduced the length of the ice season. These changes are relatively straightforward to evaluate in smaller, inland lakes. However, in large lakes, such as the North American Great Lakes, temporally intermittent and spatially heterogeneous ice cover, and spatial thermal heterogeneity limit the utility of simple ice on–off or mixing classifications; therefore, assessing how climate change is impacting winter conditions in large lakes is challenging. Here, we use in-situ and satellite-derived surface water temperature observations from the North American Great Lakes to overcome these limitations and show that warming air temperatures are driving reductions in the number of winter days, collectively those with either ice cover or inverse thermal stratification, in favor of increases in isothermal conditions for the period 1995–2023. We find that on average the Great Lakes are experiencing a loss of 14 winter days per decade. Our results demonstrate how climate change has yielded disproportionate changes in the annual thermal cycle and mixing conditions of Earth’s largest freshwater system and signals the potential for fundamental ecosystem shifts due to a loss of winter.
Testing the instanton approach to the large amplification limit of a diffraction–amplification problem
Authors: Mounaix Philippe
Published: November 2024

The validity of the instanton analysis approach is tested numerically in the case of the diffraction–amplification problem

∂
z

ψ
−

i

2
m

∂

x
2

2

ψ
=
g
|
S

|
2

ψ

for

ln
⁡
U
≫
1

, where

U
=
|
ψ
(
0
,
L
)

|
2

. Here,

S
(
x
,
z
)

is a complex Gaussian random field, z and x respectively are the axial and transverse coordinates, with

0
⩽
z
⩽
L

, and both

m
≠
0

and g > 0 are real parameters. We consider a class of S, called the ‘one-max class’, for which we devise a specific biased sampling procedure. As an application, p(U), the probability distribution of U, is obtained down to values less than 10−2270 in the far right tail. We find that the agreement of our numerical results with the instanton analysis predictions in Mounaix (2023 J. Phys. A: Math. Theor.
56 305001) is remarkable. Both the predicted algebraic tail of p(U) and concentration of the realizations of S onto the leading instanton are clearly confirmed, which validates the instanton analysis numerically in the large

ln
⁡
U

limit for S in the one-max class.
Conservation laws, traveling wave solutions and wavelet solution for the two-component Novikov equation
Authors: Mondal Supriya , Maitra Sarit
Published: November 2024

The objective of this present article is to study the two-component Novikov equation. This equation is also known as Geng–Xue equation and is characterized by cubic nonlinearities. By applying the multiplier method, new conserved quantities are found, and some traveling wave solutions are derived based on the

(

G

′

G

)

-expansion method. Furthermore, a numerical solution is determined by employing the Haar wavelet collocation (HWC) method. In order to confirm the accuracy, this numerical solution is compared with the solution obtained by

(

G

′

G

)

-expansion method. Additionally, the convergence analysis of the HWC method is also presented.
An efficient process for decomposing perfluorinated compounds by reactive species during microwave discharge in liquid
Authors: SUN 孙 Shaohua 绍华 , SUN 孙 Bing 冰 , YU 于 Zhonglin 忠林 , WANG 王 Qiuying 秋颖 , (王媛媛) Yuanyuan WANG , LIU 刘 Jinglin 景林
Published: November 2024

Microwave discharge plasma in liquid (MDPL) is a new type of water purification technology with a high mass transfer efficiency. It is a kind of low-temperature plasma technology. The reactive species produced by the discharge can efficiently act on the pollutants. To clarify the application prospects of MDPL in water treatment, the discharge performance, practical application, and pollutant degradation mechanism of MDPL were studied in this work. The effects of power, conductivity, pH, and Fe2+ concentration on the amount of reactive species produced by the discharge were explored. The most common and refractory perfluorinated compounds (perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in water environments are degraded by MDPL technology. The highest defluorination of PFOA was 98.8% and the highest defluorination of PFOS was 92.7%. The energy consumption efficiency of 50% defluorination (G50-F) of PFOA degraded by MDPL is 78.43 mg/kWh, PFOS is 42.19 mg/kWh. The results show that the MDPL technology is more efficient and cleaner for the degradation of perfluorinated compounds. Finally, the reaction path and pollutant degradation mechanisms of MDPL production were analyzed. The results showed that MDPL technology can produce a variety of reactive species and has a good treatment effect for refractory perfluorinated pollutants.