bluuebunny/crossref_metadata_2025 huggingface dataset:
GaSb-based interband cascade laser with hybrid superlattice plasmon-enhanced claddings
Authors: Petrović B. , Bader A. , Nauschütz J. , Sato T. , Birner S. , Weih R. , Hartmann F. , Höfling S.
Published: June 2024

We present an interband cascade laser (ICL) emitting at 5.2 µm consisting of an 8-stage active region and a hybrid cladding composed of outer plasmon-enhanced InAs0.915Sb0.085 and inner InAs/AlSb superlattice claddings. The hybrid cladding architecture shows an increase in mode confinement in the active region by 11.2% according to the simulation. This is a consequence of a significantly lower refractive index of plasmon-enhanced claddings. The threshold current density is 242 A/cm2 in pulsed operation at room temperature. This is the lowest value reported to date for ICLs emitting at wavelengths longer than 5 µm. We also report close to record value threshold power density of 840 W/cm2 for ICLs at such wavelengths.
Brain representations of affective valence and intensity in sustained pleasure and pain
Authors: Lee Soo Ahn , Lee Jae-Joong , Han Jisoo , Choi Myunghwan , Wager Tor D. , Woo Choong-Wan
Published: June 2024

Pleasure and pain are two fundamental, intertwined aspects of human emotions. Pleasurable sensations can reduce subjective feelings of pain and vice versa, and we often perceive the termination of pain as pleasant and the absence of pleasure as unpleasant. This implies the existence of brain systems that integrate them into modality-general representations of affective experiences. Here, we examined representations of affective valence and intensity in an functional MRI (fMRI) study (
n
= 58) of sustained pleasure and pain. We found that the distinct subpopulations of voxels within the ventromedial and lateral prefrontal cortices, the orbitofrontal cortex, the anterior insula, and the amygdala were involved in decoding affective valence versus intensity. Affective valence and intensity predictive models showed significant decoding performance in an independent test dataset (
n
= 62). These models were differentially connected to distinct large-scale brain networks—the intensity model to the ventral attention network and the valence model to the limbic and default mode networks. Overall, this study identified the brain representations of affective valence and intensity across pleasure and pain, promoting a systems-level understanding of human affective experiences.
A leadership-level culture cycle intervention changes teachers’ culturally inclusive beliefs and practices
Authors: Brady Laura M. , Wang Cong , Griffiths Camilla , Yang Jenny , Markus Hazel R. , Fryberg Stephanie A.
Published: June 2024

Despite an abundance of support for culturally inclusive learning environments, there is little consensus regarding how to change educational contexts to effectively and sustainably foster cultural inclusion. To address this gap, we report findings from a research–practice partnership that leveraged the Culture Cycle Framework (CCF) to expand educators’ praxis to include both independent and interdependent models of self. Most U.S. schools validate independent cultural models (i.e., those that prioritize individuality, uniqueness, and personal agency) and overlook interdependent models (i.e., those that prioritize connectedness, relationality, and collective well-being), which are more common among students from marginalized racial and socioeconomic backgrounds. Using a quasi-experimental longitudinal design, we trained school leadership to integrate ideas about cultural inclusion (i.e., validating the importance of both independent and interdependent cultural models) into school-wide flagship practices. We assessed downstream indicators of culture change by surveying teachers and students across the district and found that a) leadership-level training enhanced school-wide beliefs about cultural inclusion, b) teachers’ endorsement of culturally inclusive beliefs predicted their use of culturally inclusive practices, and c) teachers’ use of culturally inclusive practices predicted enhanced psychosocial and academic outcomes among students. This research represents a comprehensive culture change effort using the CCF and illustrates a means of fostering inclusion-focused educational culture change and assessing downstream consequences of culture change initiatives.
Defining migrants
Authors: Lim Lisa
Published: June 2024

In contemplating multilingualism and mobility in the 21st century, several dimensions warrant attention in the
emerging field of migration linguistics. First is the move beyond migration to thinking about mobilities, in particular, the new
mobilities paradigm in the social sciences which views human mobility as entailing a complex assemblage of movement, social
imaginaries, and experience. Second, a study of the different waves of migration in a particular society, as well as concomitant
and official language policies – using Singapore as a case in point – distinguishes the layers of, on the one hand, the older, and
thus established migrants, versus newer migrants, in particular, transient populations of foreign workers, and, crucially, the
differential statuses that these communities and their languages hold in society – including a potential invisibility of authentic
multilingualisms. Such an examination allows the development of a typology of migrants in a statal narrative. Where lines are
drawn is dependent on circumstance, with the periphery positioned differentially in times of celebration versus crisis, for
example, in risk communication in this pandemic era. This holds significant implications for access and appropriation, and
consequent (im)mobilities, and, in the bigger picture, for the crucial intersections – including how society is responding to the
role of indigenous languages for the UN’s Sustainable Development Goals. This is particularly timely for this International Decade
of Indigenous Languages (2022–2032), noted to not be addressing the interactions between language and migration, as well as the
challenge of migrant intergration, recognised as a central and important driver of sustainable development.
Private and Public Sector Differences in Adverse Incidents and Restrictive Practices: Factors That Predicted Service Sector in a National Sample of Forensic Psychiatric Inpatients
Authors: Goodwin Harriet , Davies Joseph Lloyd , Lawrence Daniel , Bagshaw Ruth , Mills Shane , Watt Andrew
Published: June 2024

Forensic mental health services play a key role in the diversion, treatment, rehabilitation, and supervision of offenders with mental health problems in Europe. Private sector providers are increasingly commissioned to provide secure care for service users. Questions have been raised about the effectiveness of the private sector providers. A sample of 229 patients from low, and medium secure psychiatric services in the United Kingdom was analyzed to determine differences in restrictive practices, adverse service user incidents, and service user characteristics between service users admitted to private sector or publicly funded hospitals. Service users with a diagnosis of a personality disorder, and those who had multiple psychiatric diagnoses were disproportionately placed in the private sector. Greater prevalence of seclusion, physical restraint, verbal aggression toward staff, physical violence toward staff and other service users, property damage, and self-harm were observed in private sector service users. Further attention is warranted around the decision-making processes that allocate people to private versus publicly funded care, potential sources of bias in admission characteristics should be taken into account when interpreting poorer clinical outcomes in the private sector.
Detection and segmentation of wire rope surface deficiency based on YOLOv8 and U-Net
Authors: Zhenbin Wang , Meishuai Han , Xun Zhang , Haisheng Li , Yinghua Chen , Wenyu Miao , Xiyao Liu
Published: June 2024

The presence of surface defects in wire ropes (WR) may lead to potential safety hazards and performance degradation, necessitating timely detection and repair. Hence, this paper proposes a method for detecting surface defects in WR based on the deep learning models YOLOv8s and U-Net, aiming to identify surface defects in real-time and extract defect data, thereby enhancing the efficiency of surface defect detection. Firstly, the ECA attention mechanism is incorporated into the YOLOv8 algorithm to enhance detection performance, achieving real-time localization and identification of surface defects in WR. Secondly, in order to obtain detailed defect data, the U-Net semantic segmentation algorithm is employed for morphological segmentation of defects, thereby obtaining the contour features of surface defects. Finally, in conjunction with OpenCV technology, the segmentation results of the defects are quantified to extract data, obtaining parameters such as the area and perimeter of the surface defects in the WR. Experimental results demonstrate that the improved YOLOv8-ECA model exhibits good accuracy and robustness, with the model’s mAP@0.5 reaching 84.78%, an increase of 1.13% compared to the base model, an accuracy rate of 90.70%, and an FPS of 65. The U-Net model can efficiently perform segmentation processing on surface defects of WR, with an mIOU of 83.54% and an mPA of 90.78%. This method can rapidly, accurately, and specifically detect surface defects in WR, which is of significant importance in preventing industrial production safety accidents.
Design dependence of noise in Nb-based dc SQUIDs
Authors: Zakosarenko V , Schmelz M , Kunert J , Il’ichev E , Stolz R
Published: June 2024

Noise in superconducting quantum interference devices (dc SQUIDs) with different design, based on Nb/AlOx/Nb technology, has been systematically measured at temperature T = 4.2 K. We demonstrate that for all our devices the power spectral density of the white noise (above a frequency of about 1 kHz) is determined by the shunt resistors, reaching about 5 times Planck’s constant. The low-frequency noise level was measured for washer- and multi-loop-type SQUIDs with systematically varied effective area, SQUID loop perimeter, and inductance. We show that at 1 Hz the noise spectral density is approximately 40 times higher than the white noise level and its scaling with washer width and effective area is negligible. These results are incompatible with several models of the flicker noise source. Possible origins of this noise are discussed.
The feed line resonator (FLR) method and it’s application to superconducting wideband filter design with extreme sharp skirt
Authors: Lu Xilong , Zhang Rui , Kong Qingyu , Zhou Shigang , Bai Xudong , Zhou Liguo , Wei Guangsong , Fang Xueyang
Published: June 2024

This paper proposes the novel concept and method of the feed line resonator (FLR). By introducing the external quality factor adjusting line, the feed lines can be transformed to resonators, and can be used not only for providing external coupling, as well as generate extra transmission poles in the passband. The conditions for generating transmission poles by using the FLR are systematically investigated. The key advancement of the FLR method is that extra transmission poles are introduced, without increase the number of conventional resonators, the filter bandwidth can be extended and the selectivity also improved. The triple-mode FLR was proposed which can realize six extra transmission poles in the pass band and n transmission zeros out-of-band. A five-section multi-mode resonator proposed for wideband filter. Single-, two-, three- and four-stage wideband superconducting filters were designed to demonstrate the FLR method. These filters exhibit extreme sharp skirts, the attenuation slop at lower and higher band can reach 273.9 dB GHz−1 and 523.7 dB GHz−1, respectively. The passband is from 2.26 GHz to 5.54 GHz with the fractional bandwidth of 95%. The measure results agree well with the simulated ones.
An analytical and machine learning model for SPD estimation and its prediction for lumen and chromaticity shift based LED lifetime performance analysis
Authors: Lokesh J , Padmasali AN , Mahesha MG , Kini S G
Published: June 2024

The LED lifetime is commonly estimated by manufacturers using an exponential model to evaluate L70 criteria. However, it ignores colour characteristic variation and does not explain the root cause of LED failure. In this paper, a spectral power distribution (SPD) based approach is proposed to estimate lifetime performance of cool white LED considering both colour characteristics and lumen maintenance, as all the lighting performance parameters are extracted from SPD. The exponential model does provide the lifetime using only lumen data and does not explain the colour characteristics. As an alternate to the exponential model, a quadratic polynomial, and machine learning (ML) models with hours and temperature as input factors, is proposed to determine SPD for experimental conditions as well as to predict for other operating conditions. Further, the lifetime performance analysis is performed for reliability assessment conditions through both lumen and colorimetric performances. The outcomes of all the models are analysed and it is found that the results are comparable. As ML models are simpler than analytical models for more than two inputs, further it is used to predict SPD at different temperatures and the LED performance is validated. Further analysis shows that a decrease in blue light is the primary cause of the overall decrease in light output and decrease in yellow emission due to phosphor degradation is the reason for chromaticity shift.
Microscopic derivation of the octupole magic numbers from symmetry considerations
Authors: Martinou Andriana , Minkov Nikolay
Published: June 2024

The valence shells of medium mass and heavy nuclei consist of the normal and the intruder parity orbitals; therefore the Shell Model SU(3) symmetry of Elliott cannot have a straightforward application on them. The proxy-SU(3) can be applied instead, since it uses a unitary transformation, meant to act on the intruder orbitals to alter their parity and transform them to their proxy orbitals. The inverse unitary operator transforms the proxy orbitals back to the intruder ones. The highest weight proxy-SU(3) irreducible representations (irreps) allows one to determine the corresponding number of occupied intruder orbitals. In this way we obtain the so-called ‘octupole magic numbers’ 32, 56, 90, 134 and 194 without any parameter. Moreover, the proxy (unitary) mapping and its inverse transformation make the proxy space eligible for the calculation of observables associated with octupole deformation and the relevant treatment of mixed parity states. The implemented study validates the proxy-SU(3) approach with respect to the octupole deformation and suggests its full applicability in the corresponding mass regions.
Intertwined quantum phase transitions in the zirconium and niobium isotopes
Authors: Gavrielov N
Published: June 2024

Nuclei in the A ≈ 100 region exhibit intricate shape-evolution and configuration crossing signatures. Exploring both even–even and their adjacent odd-mass nuclei gives further insight on the emergence of deformation and shape-phase transitions. We employ the algebraic frameworks of the interacting boson model with configuration mixing and the new interacting boson-fermion model with configuration mixing in order to investigate the even–even zirconium with neutron number 52–70 (40Zr) and odd-mass niobium (41Nb) isotopes with 52–62. We compare between the evolution in energy levels, configuration and symmetry content of the wave functions, two neutron separation energies and E2 transition rates, alongside comparison with the experimental data. The comparisons between the two chains of isotopes denote the occurrence of two types of QPTs, a crossing of normal and intruder configurations (named Type II QPT), and a shape-evolution of the intruder configuration (named Type I QPT). The latter QPT begins from spherical shape to axially deformed rotor in the Zr isotopes and from weak to strong coupling scenario in the Nb isotopes. This occurrence, named intertwined quantum phase transitions (IQPTs), in the even–even Zr chain is thus demonstrated to persists when coupling a proton to the boson core for the odd-mass Nb chain, even as deformation increases.
Dynamic analysis of a skeet-inspired vehicle to achieve a spiral scanning detection motion
Authors: Yang Yongliang , Ding Zijing , Sun Guangrui
Published: June 2024

A short cylindrical vehicle (the ratio of length to diameter is less than 2) equipped with an outer/inner detector is developed, which is inspired by the Tennis racket theorem and Olympic skeet shooting sports to achieve a regular scanning spiral on the ground. The sensitivity of the asymmetric mass distribution of the skeet-inspired vehicle (SIV) to the spatial position of the inertial principal axis is evaluated. Subsequently, a dynamics model with six degrees of freedom for the SIV at a large initial angle of attack (≈60–90°) is established. The numerical results of solving the dynamic differential equations indicate that the special initial conditions—namely, high initial flying velocity and rotational speed—are prerequisites for achieving the regular scanning spiral. Additionally, the analysis demonstrates that asymmetric mass distribution, rather than asymmetric aerodynamics, serves as the key factor in achieving the regular scanning spiral in the present skeet-inspired vehicle. Our new strategy, using the principal axes as the initial rotation axis, offers better scanning performance (such as a larger detection area, faster scan frequency, and more stable scanning motion) compared to the other platforms (e.g., rotating decelerators with wings or parachutes) that rely on asymmetrical aerodynamics. The analyses can provide guidance for the structural design of various types of spiral scanning vehicles.
Optical properties and antimicrobial of ionic chitosan-MgO-SiO2@ aminolsilane nanocomposites
Authors: Abouelnaga Amel Mohamed , Abou Hammad Ali B
Published: June 2024

This investigation involved synthesizing a nanocomposite heterostructure, Chitosan-MgO-SiO2@aminosilane, using the physical blending of chitosan-MgO-silica with aminosilane using the sol–gel technique. The prepared nanocomposites were characterized using x-ray diffraction (XRD), Scanning/Transmission Electron Microscope (SEM-EDX/TEM), Fourier Transform Infrared Spectroscopy (FTIR), and optical analysis to investigate the microstructural and spectroscopic properties. XRD results confirmed the formation of orthorhombic Mg2SiO4 within the fabricated system. FTIR analysis verified interactions among chitosan, MgO-silica, and aminosilane, leading to the development of diverse functional groups, including M-O bonds, silanol-hydroxyl ions, and heteropolymeric-O-M within the chitosan-MgO-SiO2@aminosilane nanocomposite. Optical studies demonstrated that aminosilane-incorporated samples have two distinct absorption bands around 215 nm and 419 nm, corresponding to the electronic transitions π–π* (k-band) and n–π* (R-band), respectively. The absorption band at 400 nm is ascribed to localized surface plasmon resonance (SPR). The incorporation of aminosilane resulted in a decrease in the direct transition energy gap from 2.677 to 2.399 eV. The nanocomposites displayed significant antimicrobial activity against pathogenic microorganisms such as Gram-positive Staphylococcus aureus, Gram-negative Pseudomonas aeruginosa, and pathogenic fungi Candida albicans and Aspergillus niger. The positive antimicrobial response of the fabricated nanocomposites candidates them for various applications, including wound dressings and food packaging.
Impact of dephasing probes on incommensurate lattices
Authors: Ghosh Bishal , Mohanta Sandipan , Kulkarni Manas , Kumar Agarwalla Bijay
Published: June 2024

We investigate open quantum dynamics for a one-dimensional incommensurate Aubry–André–Harper lattice chain, a part of which is initially filled with electrons and is further connected to dephasing probes at the filled lattice sites. This setup is akin to a step-initial configuration where the non-zero part of the step is subjected to dephasing. We investigate the quantum dynamics of local electron density, the scaling of the density front as a function of time both inside and outside of the initial step, and the growth of the total number of electrons outside the step. We analyze these quantities in all three regimes, namely, the de-localized, critical, and localized phases of the underlying lattice. Outside the initial step, we observe that the density front spreads according to the underlying nature of single-particle states of the lattice, for both the de-localized and critical phases. For the localized phase, the spread of the density front hints at a logarithmic behavior in time that has no parallel in the isolated case (i.e. in the absence of probes). Inside the initial step, due to the presence of the probes, the density front spreads in a diffusive manner for all the phases. This combination of rich and different dynamical behavior, outside and inside the initial step, results in the emergence of mixed dynamical phases. While the total occupation of electrons remains conserved, the value outside or inside the initial step turns out to have a rich dynamical behavior. Our work is widely adaptable and has interesting consequences when disordered/quasi-disordered systems are subjected to a thermodynamically large number of probes.
The effect of lug parameters on titanium alloy lug’s detail fatigue rating
Authors: Li Chongyuan , Yao Weixing
Published: June 2024

This article introduces a method to determine the Detail Fatigue Rating (DFR) of lugs through constant amplitude fatigue testing. Fatigue tests of titanium alloy lugs were designed, and the DFR of lugs was calculated based on the test results. A comparative analysis was conducted from two aspects: the relative width (d/b) and the loading direction (θ) of straight lugs, and the effect of lug parameters on the DFR was discussed. The results indicate that the DFR of lugs is positively correlated with the relative width (d/b) and negatively correlated with the loading direction (θ).
Study on damage response characteristics of steel plate-aramid composite structure under a combination of shock wave and fragment
Authors: Wang Zhenyu , Zhou Yunbo , Zhang Ming
Published: June 2024

To look into the damage response of steel plate/aramid composite structure under the combined action of shock wave and debris, the finite element models of TNT, debris, and target plate are established. LS-DYNA is used to analyze the structural response process of the composite structure under the synergism of blast wave and debris. The reliability of the numerical model is verified by comparing the trial results with the analytic results. The structural response of the single and combined loading of blast wave and debris is analyzed, and the influence of the arrangement order and thickness ratio of the target plates on the protective effectiveness is further analyzed. The results indicate that the combined action of blast wave and debris causes greater damage than the single action of blast wave and debris. When the total thickness of the plate remains unchanged, as the thickness of the panel decreases, the mass loss of the plate decreases, the peak displacement of the back plate decreases, and the protective ability of the plate is enhanced. In addition, the protective ability of the Steel-Aramid-Steel plate structure is greater than that of the Steel-Steel-Aramid plate structure.
Molecular dynamics simulation of CoCrFeMnNi with twin boundaries under high-speed impact
Authors: Yao Xiangtian , Li Haitao
Published: June 2024

Based on the hybrid modeling framework of atomic scale and continuum, molecular dynamics (MD) was the method to study the shock wave, elastic-plastic dual-wave, and microstructure of CoCrFeMnNi high entropy alloy (HEA) with twin boundary under high-speed impact. The interaction between dislocation and twin interfaces is significant to the plastic deformation of HEA, but research on them as initial defects is still limited. Therefore, this article simulates and analyzes the impact velocity and twin spacing and proves that HEA with twin boundaries can synergistically improve strength and flexibility by comparing the wave simulation process and variation of spalling strength between HEA with TB and crystal Ni. The simulation results show that TB affects the propagation of shock waves in HEA and provides deformation sites for the generation of dislocations. Unlike single-crystal HEA, there is a smoother impact response process, and the maximum tensile stress during the fracture stage can reach 41 GPa, which is about 34.12% higher than that of single-crystal HEA. The research results may contribute to a better understanding of HEA with TB and help apply complex load scenarios such as explosive loads.
The study on mechanical properties of the vibration isolator
Authors: Luo Xiancheng
Published: June 2024

First of all, the working principle of vibration reduction of the vibration isolator is briefly introduced. The vibration isolator adopts the design ideal of no formant and adopts a damping locking mechanism in the resonance region to solve the problem of vibration amplification of the system. The purpose of vibration attenuation is to use small damping in the attenuation region. Then, through the numerical simulation calculation method, it can be obtained that the isolator has a good vibration isolation effect under different effects of shock and impact, and the effective rate is about 90%, which fully guarantees the structural safety of the test equipment. Finally, according to an example, a model is established to study the influence of equipment weight and center of gravity design deviation on the natural frequency and natural frequency point vibration transmission efficiency of the equipment. Through analysis, it can be found that in the case of no abnormality of the equipment, the frequency is changed in the range of 1∼160 Hz, and the ratio of the system response to excitation is not more than 2, which meets the design requirements.
Investigation of the kinematics behavior of spherical detector with different diameter ratios in oil pipelines
Authors: Miao Rui , Chen Yingchun , Song Wei , Fan Xiaoli , Ye Wei , Guo Penghui
Published: June 2024

The spherical detector is an important technical equipment for water supply pipeline leakage detection. Its stable operation inside the pipeline will be affected by the fluid state in the pipeline, and the motion law of detectors with different diameters is different. In this paper, the dynamic analysis is carried out using the numerical simulation method, and the motion of spherical detectors with different diameters in horizontal oil pipelines is simulated. It is found that the flow state of the detector changes from the acceleration stage to the stable stage during the motion process, and with the decrease of the diameter ratio, the pressure difference between the front and back of the detector gradually increases, the thrust shows an upward trend, and the speed shows a greater speed in the stable stage. The motion behavior of the detector under different pipe diameter ratios is obtained, which provides help for the subsequent optimization of the shape design of the micro-leakage internal spherical detector.
Impact of la on steel inclusions: a first-principles investigation into elastic properties and anisotropy
Authors: Song Yan , Li Can , Qiao Qi , Ren Lei , Yang Jichun
Published: June 2024

This study employed first-principles calculations based on density functional theory to explore the La-induced modifications in the elastic properties of inclusions at the microscopic level. Initially, through formation energy calculations, stable La2O3, La2O2S, and LaAlO3 inclusions were identified after the treatment with the rare earth element La. Subsequently, the elastic moduli and anisotropy of both the steel matrix and the inclusions were computed. The results revealed a substantial difference in the average elastic moduli between the common inclusions MnS, Al2O3 and the steel matrix, indicating their non-ductile nature. Conversely, La-modified inclusions, such as La2O2S and LaAlO3, exhibited closer average elastic moduli to the steel matrix with reduced anisotropy, mitigating stress concentration. This elucidates one of the reasons behind the enhanced fatigue performance of La-doped steel.
Effect of gradient nanostructures on the damage mechanism of aermet100 steel at various strain rates
Authors: Yan Yabin , Yao Jiancheng , Wang Bolong , Zhen Long
Published: June 2024

The introduction of nano-scale grains, which form a gradient nanostructure (GNS) within the material, usually increases the service life of metallic materials. In this study, the uniaxial tensile mechanical properties of AerMet100 steel in initial and GNS states under different strain rate conditions were compared, and the microanalysis of tensile fracture was performed. It is found that GNS has little effect on the mechanical properties of AerMet100 but has an effect on its damage mode. The initial AerMet100 was basically ductile fracture, and GNS increased the brittle fracture mode in AerMet100.
Simulation of ultrasonic shear effect on the viscoelastic soft scale of heat exchangers
Authors: He Zhaokui , Wang Hehui
Published: June 2024

The shear effect on the viscoelastic soft scale of heat exchangers is simulated in this study, focusing on a chemical company’s heat exchanger and the associated fouling on its inner tube shell wall. The finite element software ABAQUS simulates the ultrasonic descaling process, incorporating viscoelastic soft scale materials into the calculations through software fitting functions. Based on ABAQUS data transfer technology, the model was first subjected to implicit static analysis, followed by explicit kinetic analysis containing pre-stress. The vibration propagation of ultrasonic waves on the heat exchanger model was simulated under different working conditions. Distribution of shear stresses of the fouling on different paths of the pipeline wall was obtained, and the results revealed the influence of different parameters of the ultrasonic waves on the shear descaling effect, which provides a reference for selecting appropriate parameters to improve the efficiency of ultrasonic descaling.
The Science of Making Torque from Wind 2024 (TORQUE 2024)
Authors: Bianchini Alessandro
Published: June 2024

Wind energy is almost unanimously thought to be a key catalyst in enabling a rapid transition from fossil fuels to a system based largely on renewable power. If the history of wind energy in the last fifty years has been to a large extent a success, it still needs to progress to respond to the new challenges coming from the upscaling of the rotors and their deployment in new installations, such as deep-water offshore ones [1].

These challenges span over a large spectrum of disciplines and sciences, from a better definition of the characteristics of the wind, through how the wind inflow translates to loads and performance, to how best to build and operate the wind farms and integrate them into the grid. Europe was, and aspires to remain, a hub for scientific research in wind energy and the European Academy of Wind Energy (EAWE) was created to bring together the top research institutes active in wind energy to cooperate, share knowledge and promote scientific excellence [2].

As part of this remit, the conference, The Science of Making Torque from Wind (or TORQUE, for short) was first held in 2004 in Delft. The conference has gone from strength to strength and is probably the largest scientific conference devoted to wind energy in the world. After the very successful edition that came back to Delft in 2022, the 2024 edition of TORQUE in Firenze has seen an unprecedented number of abstracts submitted, confirming the increasing interest by the scientific community.

Following the call for three-page abstracts (575), the contributions were reviewed in double-blind form by experts in the field, ensuring that an impartial evaluation of their scientific merit was given. After full submissions have been invited, a two-stage peer review process was carried out by over 500 reviewers and 426 full papers were accepted for publication in the proceedings. The conference consisted of 4 plenary sessions, 36 parallel oral sessions and two poster sessions. Oral presenters had 15 minutes to present their work followed by 5 minutes of questions. All poster presenters were allowed a recorded one-minute pitch which could be accessed in advance of the live poster sessions.

Posters and parallel sessions are grouped under eight broad themes that have been overseen by several experts in the field.
Towards LES-RANS/LES coupling for simulation of a wind turbine rotor in a nocturnal atmospheric condition
Authors: Imiela Manfred , Wrba Linus , Probst Axel , Bangga Galih , Englberger Antonia
Published: June 2024

A segregated approach with either synthetically generated velocity fluctuations or a precursor Large-Eddy Simulation (LES) of the atmospheric boundary layer (ABL) and a subsequent hybrid RANS/LES (HRLS) of the resolved rotor is presented in this paper. At first the approach is validated with synthetically generated velocity fluctuations that resemble neutrally stratified conditions. Subsequently the same turbine is artificially exposed to a stably stratified atmospheric inflow (nocturnal boundary layer) with a comparable mean velocity but different shear and veer characteristics. The HRLS simulations with the neutrally stratified and stably stratified inflow are compared to LESs with an implemented actuator disc (AD) model. The presented work is a first important step towards a digital twin for research wind parks.
Assessment of the azimuthal loads variation by a bi-rotor configuration
Authors: Martín-San-Román Raquel , Cerrada-Garcés Jon , Campaña-Alonso Guillén , Méndez-López Beatriz , Azcona-Armendáriz José , Cuerva-Tejero Alvaro
Published: June 2024

Multi wind turbine configurations are emerging in the offshore wind energy market. The modelling of the aerodynamics of these systems is challenging, due to the small lateral distance between rotors and the subsequent interaction between wakes. Previous analysis in the literature showed that, due to this interaction, multi wind turbine concepts present the advantage of an increment in power production, if the rotors are laterally aligned. However, the counterpart in the variation of the blade loads throughout the revolution, has yet to be analysed in depth. This study focuses on the differences observed in azimuthal cycles of blade aerodynamic loads in side-by-side bi-rotor configurations, as an initial analysis of their potential impact on fatigue loads. The analysis has been developed using two aerodynamic codes, with different levels of fidelity. These models are: a Free Vortex filament Method (FVM) combined with an unsteady Lifting Line (LL) model, and a URANS-blade resolved approach. The simulations show that the sectional blade loads are affected by the adjacent rotor, changing the shape of the aerodynamic load cycles along the azimuth. The load azimuthal distributions predicted by a FVM and a URANS models have been compared, showing agreement on the shape of the cycle with slight differences on maximum peak values, specially at the inner sections of the blade. The FVM model has predicted increments in the blade load cycles, with respect to a single rotor case, with a maximum amplitude of a 3% for out-of-plane forces, and a 8% for in-plane forces. The difference in the azimuthal position of both rotors (phase shift angle) mainly affects the azimuthal shape and not so much the characteristic amplitude of these cycles. Finally, including geometric angles as tilt or pre-cone, produces imbalances between the blade sectional forces of the different rotors.
Impact of dynamic stall model tailoring on wind turbine loads and performance prediction
Authors: Chellini Simone , De Tavenier Delphine , Von Terzi Dominic
Published: June 2024

The future of wind turbines will be characterised by long, slender blades subject to dynamic inflow and aeroelastic deflections. This makes the next generation of blades more prone to encounter dynamic stall effects, in which significant forces and loads fluctuations can be expected. Dynamic stall models can be tailored to suit the aerodynamics of different airfoils. Although different dynamic stall models exist, the impact of the choice of model, its implementation and calibration on the overall wind turbine performance remains to be assessed. In this work, we gathered an experimental dynamic dataset for a representative airfoil, the FFA-W3-211, to define the semi-empirical time constants for the Beddoes-Leishman dynamic stall model. An important differentiation is made between stall regions for positive and negative angles of attack, and the impact of tailored coefficients is assessed at airfoil scale. The difference between the tailored and untailored model is quantified for power performance and loads of the IEA 15 MW reference wind turbine. The results highlight a significant load over-prediction from the untailored Beddoes-Leishman model, whereas changes in power performance are negligible.
Limitations of lift correction models for thick airfoils in wind turbine roots
Authors: Céspedes J F , Bak C , Zahle F
Published: June 2024

The flow in wind turbine blade root sections has proven to be challenging to predict for two main reasons; the use of thick airfoils (relative thickness greater than 40%) and three-dimensional effects including a strong radial flow. Several lift correction models have addressed these 3D effects acting on the inner part of rotating blades, however, they are derived for thinner airfoils in a stall-delay context, which changes significantly in thick airfoils, as found in modern wind turbines. This study numerically evaluates the performance of a 10 MW reference rotor in realistic operational conditions, as well as analytical rotors, in 3D and 2D CFD computations. It is found that, for thick airfoils, traditional lift correction models under-predict the lift coefficient by more than 1, depending on the operational conditions. But for non-thick airfoils, the difference between predicted and real lift coefficient is typically less than 0.5. Furthermore, a new correction term is proposed, which considers the effects introduced by thick airfoils and brings the overall error to the same level as for non-thick sections.
Development of a FW-H tool coupled with CFD for infrasound noise emissions from wind turbines
Authors: Shah AH , Sucameli CR , Bottasso CL
Published: June 2024

Noise remains an obstacle to the advancement of onshore wind energy. Despite the ongoing debate on the effects of infrasound on human health, especially from wind turbines, there is consensus that the blade passing frequency (BPF) in the infrasound range modulates the audible higher-frequency sound and creates a rhythmic “swishing” sound at farther distances. This paper presents a simulation framework for assessing infrasound noise (<20 Hz) from wind turbines, which was designed to capture the relevant physics without incurring in overwhelming computational costs. The flow is modelled using large eddy simulation (LES) and is coupled through an actuator line method (ALM) to the aeroelastic model of a wind turbine. The use of an ALM significantly reduces the computation effort compared to blade-resolved CFD approaches. Moreover, the Ffowcs Williams-Hawkings (FW-H) acoustic analogy is applied on a permeable integration surface that surrounds the entire wind turbine, thereby capturing the coupled effects of rotor, tower, and the near-wake turbulence shed by the turbine. The present approach is shown to be capable of resolving rotor-tower interactions as tonal peaks at BPF and its harmonics, enabling the evaluation of design and control measures to mitigate infrasound noise emissions from wind turbines.
Experimental investigation of the occurrence of transonic flow effects on the FFA-W3-211 airfoil
Authors: Aditya Abhyuday , De Tavernier Delphine , Schrijer Ferdinand , Van Oudheusden Bas , Von Terzi Dominic
Published: June 2024

For the largest wind turbines currently designed, when operating at rated power and at high wind speeds, the tip airfoils can experience large negative angles of attack. For these conditions and in combination with turbulence, the airfoils are at risk of reaching locally supersonic flow, even at low free-stream Mach numbers. The possibility of shock wave formation and its consequences endangers the lifetime of these largest rotating machines ever built. So far only numerical analyses of this challenge have been attempted with significant modelling uncertainty. Here, for the first time, a wind turbine airfoil (the FFA-W3-211, used at the blade tip of the IEA 15MW reference wind turbine) is studied under transonic conditions using experimental techniques. Schlieren visualization and Particle Image Velocimetry were employed for free-stream Mach numbers of 0.5 and 0.6 and various angles of attack. It was shown that calculations based on isentropic flow theory and compressibility corrections were able to predict the situations where supersonic flow occurred. However, they could not predict the frequency of occurrence and whether shock waves were formed. In conclusion, an unsteady characterization of such airfoil behavior in transonic flow seems to be warranted.
Estimating the performance of wind turbines misaligned with respect to the wind direction using a simplified CFD based approach
Authors: Basu Sudipta Lal , Fitzgerald Breiffni , Basu Biswajit
Published: June 2024

Wind direction in atmospheric boundary layer changes constantly. As such, the power extracted from the wind turbines in a wind farm is subjected to change. This change in wind direction impacts the wake pattern which in turn affects the power output of the downstream wind turbines. Empirical wind farm models are useful in such cases to assess the overall performance of the wind farms. However, the results provided by these models can be made more useful if fluid-structure interaction (FSI) effects are also considered. In the present work, we begin by looking at the potential flow model and the issues associated with it and used a modified model with constant vorticity to analyze the wind power available to the downstream wind turbines in a wind farm misaligned with respect to wind direction for irrotational flow. A simplified FSI based approach is used to carry out the simulations without the need of modelling the complicated wind turbine geometry.
Aerodynamic Characterization of the IEA 15 MW Reference Wind Turbine by Code-to-Code Comparison
Authors: Tieghi Lorenzo , Morici Vincenzo , Castorrini Alessio , Aryan Navid , Greco Luca
Published: June 2024

The consistency of different aerodynamic formulations applied to the analysis of a modern multi-megawatt horizontal axis wind turbine rotor is investigated. The proposed code-to-code comparison involves specific implementations of a hierarchy of solvers based on Blade Element Momentum Theory (AEOLIAN), Actuator Line Modelling (OpenFOAM), free-wake Panel Method (FUNAERO) and blade-resolved Computational Fluid Dynamics (OpenFOAM ). The analysis addresses local and integral aeroloads and flow physical quantities concerning the state-of-the-art IEA 15 MW reference wind turbine in axial uniform flow conditions. The proposed solvers predict consistent rotor performance and blade aeroloads (also in line with data from of IEA Task 47). However, differences emerge close to blade root, where blade-resolved CFD reveals a significant flow separation on the suction side. Furthermore, scattering of induction factors computations is observed, especially in the axial direction. Different methodologies and numerical setup used in blade-resolved simulations allow achieving physically-consistent induction values, especially at blade tip. Finally, flow-field predictions by Computational Fluid Dynamics (CFD) and Panel Method are consistent upstream and close to the disk downstream (except where significant flow separation occurs), whilst a more detailed study on the effect of extending wake refinement zone in CFD simulation is advisable.
Exploration of an analytical, linear two-dimensional actuator disc model as basis for a general rotor induction model
Authors: Aa. Madsen H.
Published: June 2024

The state of the art BEM based aerodynamic and aeroelastic modelling is challenged by effects rising from the upscaling of wind turbine rotors such as non-planar rotor shapes due to increased blade bending and large instantaneous load variations over the rotor disc due to inflow turbulence and shear. This calls for new engineering aerodynamic modelling approaches. We present such a new approach by exploration of the implementation of an analytical 2-D actuator disc (AD) model called 2D
l
for use as a rotor induction model. The overall approach is to use superposition of an elementary analytical single yawed disc solution with a constant loading to build an arbitrary rotor shape and loading from several discs. This means that we have the basis for a simple integrated induction model without sub-models that can simulate the 2-D induction from an arbitrary rotor shape such as coning and in any yaw angle. In the paper we demonstrate the principles of how to generate the disc shape and loading on two coned rotors and on a 30 deg yawed rotor where the baseline is a modified version of the IEA-10.0-198 10MW reference wind turbine. We compare the results with the HAWC2 code and a recently developed code HAWC2-BEM-VC combining BEM and a vortex cylinder model for simulation of non-planar rotors. The results clearly show how important it is to include the lateral velocity component in both the coned and yawed flow cases as this velocity has a big impact on the velocity component normal to the disc which is closely related to loads on the rotor.
Towards blade-resolved ice accretion simulations of flexible blades using mixed-fidelity models
Authors: Caccia Francesco , Abergo Luca , Guardone Alberto
Published: June 2024

We present a modular framework for blade-resolved fluid-structure interaction simulations of rotors. The framework is based on the coupling of the multi-body solver MBDyn with the fluid solver SU2 using the library preCICE. A preliminary validation is carried out against other open-source codes analysing the UAE Phase VI experiment. In the future, the framework will be used to study ice accretion on flexible blades. Indeed, blade flexibility has not been considered yet in the numerical modelling of ice accretion due to lacking computational tools and high computational costs. A first application on ice accretion is shown by analyzing the temporal evolution of the modal frequencies of an isolated blade during an icing event simulated numerically with a quasi-3D approach. The results provide insight into the nature of ice throw from wind turbines.
Reynolds effects on wall pressure fluctuations at stall inception of a wind turbine blade section
Authors: Hanna B. , Braud C. , Podvin B. , Deparday J.
Published: June 2024

Understanding the flow physics over airfoils near stall is of major importance for improvement of dynamic stall models. However, static stall is a first important step that remains challenging. The present study focuses on the influence of Reynolds number on the stall inception of an airfoil, one of the important parameter impacting the stall behavior. The blade, extracted from scans of an operated 2MW turbine, is investigated experimentally at full scale using two chordwise lines of unsteady wall pressure sensors with Reynolds numbers ranging from 5 × 105 to 4.2 × 106. Results reveal an important dependence of the pressure fluctuations with the Reynolds number: their relative level compared with the intrados value is progressively increased with the Reynolds number in the intermittent separation region which corresponds to the peak of pressure standard deviation.