bluuebunny/crossref_metadata_2025 huggingface dataset:
The NERIS roadmap: research challenges in emergency preparedness, response and recovery
Authors: Bexon A. , Andronopoulos S. , Croüail P. , Montero Prieto M. , Oughton D. , Raskob W. , Turcanu C. ,   on behalf of the NERIS platform R&D committee
Published: June 2023

NERIS as a European Platform on Preparedness for Nuclear and Radiological Emergency Response and Recovery (EPR&R) has developed a roadmap setting out the key research challenges for radiation emergency preparedness, response and recovery. Research projects in this field have been summarised to demonstrate how important areas of development have been identified and addressed. Radiation EPR&R has a continuous need to evolve to meet societal demands, but also to keep pace with scientific and technological developments and opportunities and so the NERIS research priorities as published in the Strategic Research Agenda (SRA) are kept under review. Three challenge areas have been identified covering the topics of radiological impact assessment, protective action strategies and establishing a transdisciplinary and inclusive framework for emergency preparedness, response and recovery. The importance of these challenge areas and the underlying key topics for NERIS have been mapped across to the Joint Radiation Protection Roadmap developed by the consortium of European radiation research platforms known as MEENAS. The war in Ukraine triggered a new round of revision of the SRA that resulted in the identification of four topics as new or revised challenges for the NERIS community. These updated challenges are: (1) optimisation of management strategies for the transition and recovery phase, (2) uncertainty quantification, data assimilation and monitoring strategies, (3) inverse modelling, and (4) lessons identified from Ukraine and implications for emergency preparedness. These four areas will form the priority research areas for the NERIS community to help advance radiation emergency preparedness to meet current challenges and needs that have been identified.
Aerobic Training Increases Hippocampal Volume and Protects Cognitive Function for Type 2 Diabetes Patients with Normal Cognition
Authors: Wang Ying , Wang Liping , Yan Juan , Yuan Xiaodan , Lou Qing Q.
Published: June 2023

Aim To evaluate the effects of aerobic training on hippocampal volume and cognitive function in patients with type 2 diabetes mellitus (T2DM) with normal cognition.

Materials and methods One hundred patients with T2DM aged 60–75 years who met inclusion criteria were randomized into the aerobic training group (n=50) and control group (n=50). The aerobic training group received 1 year of aerobic training, while the control group maintained their lifestyle without additional exercise intervention. The primary outcomes were hippocampal volume measured by MRI and Mini-mental State Examination (MMSE) score or Montreal Cognitive Assessment scale (MoCA) scores.

Results Eighty-two participants completed the study (aerobic training group, n=40; control group, n=42). There was no significant difference between the two groups at baseline (P>0.05). After one year of moderate aerobic training, increase in total and right hippocampal volume in the aerobic training group were significantly higher than in the control group (P=0.027, P=0.043, respectively). In the aerobic group, total hippocampal volume significantly increased after the intervention compared with baseline (P=0.034). The between-group difference in the change of MMSE and MoCA scores was statistically significant (P=0.015, P=0.027, respectively). Logistic regression showed strong correlations between aerobic training and increase in total hippocampal volume (OR:1.091, [95%CI 0.969, 1.228], P=0.002), improvement of MMSE scores (OR:1.127, [95%CI 1.005, 1.263], P=0.041) or MoCA scores (OR:2.564, [95%CI 2.098.2.973], P=0.045).

Conclusions One-year moderate aerobic training increased total and right hippocampal volume and protected cognitive function for T2DM patients with normal cognition. Early intervention focusing on cognition protection should be considered for T2DM patients in clinical settings.
Palladium-Catalyzed Oxidative Cycloaddition of Quinazoline-2,4(1H,3H)-diones and Diarylalkynes via C–H/N–H Activation
Authors: Stepakov Alexander V. , Komolova Darya D. , Pronina Yulia A. , Lozovskiy Stanislav V. , Selivanov Stanislav I. , Ponyaev Alexander I. , Filatov Alexander S. , Boitsov Vitali M.
Published: June 2023

The oxidative cycloaddition of 3-subsituted quinazoline-2,4(1H,3H)-diones and alkynes has been developed. The reaction is Pd(II)-catalyzed and successfully occurs in the presence of Ag(I) oxidants. This transformation is assumed to proceed by N–H palladation of the quinazoline-2,4(1H,3H)-dione followed by ortho-C–H activation. Using this methodology, a series of 5,6,7,8-tetraaryl-1H-azepino[3,2,1-ij]quinazoline-1,3(2H)-diones were obtained in moderate to good yields. The resulting tricyclic heterocycles can be converted by alkaline hydrolysis into 1H-benzo[b]azepine-9-carboxamide derivatives. DFT calculations have been carried out to shed light on the reaction mechanism.
Data security crisis in universities: identification of key factors affecting data breach incidents
Authors: Li Jin , Xiao Wei , Zhang Chong
Published: May 2023

The extremely complex and dynamic digital environments of universities make them highly vulnerable to the risk of data breaches. This study empirically investigated the factors influencing data breach risks in the context of higher education, according to crime opportunity theory and routine activity theory. The data consisted of university samples from China and were collected mainly from the Chinese Education Industry Vulnerability Reporting Platform. After applying Poisson regression for the estimation, increased public disclosure of vulnerabilities was found to escalate the frequency of data breaches, whereas cross-border data flow decreased the number of data breaches. Furthermore, the mechanism by which academic strength affects data breaches was examined through the two mediators of cross-border data flow and vulnerability disclosure. In addition, cloud adoption reduced data breaches, and public clouds were determined to be relatively more secure than private clouds. Cloud adoption also acted as a moderator between the negative impact of vulnerabilities and the positive impact of cross-border data flow on data breaches. The estimation and robustness findings revealed the underlying mechanisms that impacted university data security, clarifying the understanding of data breaches and suggesting practical implications for universities and other institutes to improve information security. The findings of this study provide insights and directions for future research.
How quiet is the quietest supersonic aircraft?
Authors: Thompson Avery
Published: May 2023

Estimations of the noise level of NASA’s experimental X-59 supersonic aircraft will help inform future community flyovers.
Advantages of adding a weak second gate in sub-micron bottom-contact organic thin film transistors
Authors: Yoon Chankeun , Zhou Yuchen , McCulley Calla M. , Liang Kelly , Dodabalapur Ananth
Published: May 2023

It is shown that in bottom gate, bottom-contact sub micrometer organic thin-film transistors (TFTs) with Dinaphtho[2,3-b:2′,3′-f]thieno-[3,2-b]thiophene active semiconductors, the addition of a top gate results in substantial improvements in a whole range of electrical performance characteristics. These improvements are not due to additional charge induced by the top gate but originate from the spatial redistribution of the charge induced by the bottom gate by the top gate. In the TFTs described in this work, the bottom gate insulator consists of a bilayer of SiO2 and solution-deposited high-k ZrO2, while the top gate insulator is a relatively thick CYTOP® layer deposited from a solution by spin coating. The capacitances per unit area of the bottom gate insulator and top gate insulator are 87 and 8 nF/cm2, respectively. On account of this large difference, the top gate is referred to as “weak,” as its ability to induce charges in the channel is very much limited. The use of a weak top gate is shown to result in large improvements in the on-state drain current, sub-threshold swing, threshold voltage, and contact resistance compared to single gate operation. Weak top gates are especially useful when processing constraints make it difficult to realize symmetric or close to symmetric dual gate designs. While this demonstration is for a specific materials system, the design principle is more general and is likely to benefit a range of short channel length TFTs including organic/polymer, amorphous metal oxide, and 2D semiconductor-based transistors.
Influence of surface adsorption on MoS2 memtransistor switching kinetics
Authors: Cain John M. , Yan Xiaodong , Liu Stephanie E. , Qian Justin H. , Zeng Thomas T. , Sangwan Vinod K. , Hersam Mark C. , Chou Stanley S. , Lu Tzu-Ming
Published: May 2023

Sulfur-deficient polycrystalline two-dimensional (2D) molybdenum disulfide (MoS2) memtransistors exhibit gate-tunable memristive switching to implement emerging memory operations and neuromorphic computing paradigms. Grain boundaries and sulfur vacancies are critical for memristive switching; however, the underlying physical mechanisms are not fully understood. Furthermore, the adsorption of water and gaseous species strongly perturbs electronic transport in monolayer MoS2, and little work has been done to explore the influence of surface interactions on defect-related kinetics that produces memristive switching. Here, we study the switching kinetics of back-gated MoS2 memtransistors using current transient measurements in a controlled atmosphere chamber. We observe that adsorbed water molecules lead to suppression of the electronic trap-filling processes concomitant with the resistive switching process, resulting in altered kinetics of the resistive switching. Additionally, using the transient response from “bunched” drain voltage pulse trains performed as a function of temperature, we extract the energy of the affected trap state and find that it places the trap roughly midgap [ET=EC – 0.7 (±0.4) eV]. Our results highlight the importance of controlling for surface interactions that may affect switching kinetics in 2D memtransistors, synaptic transistors, and related memory devices.
Subwavelength focusing and steering of spoof acoustic surface waves with aperiodic waveguide arrays
Authors: Xie Peng-Xiang , Sheng Zong-Qiang , Huang Ze-Xin , -Hu Ping , Wu Hong-Wei
Published: May 2023

In this study, we designed an acoustic waveguide by setting small periodic rigid plates to support spoof acoustic surface waves that can be freely controlled by tailoring the waveguide widths. When constructing acoustic waveguide arrays with parabolic refractive-index distributions, sound can be steered to focus on deep-subwavelength focal points, surpassing the diffraction limit. Theoretically, we used the Hamiltonian optics method to predict the focusing position and propagation trace of the spoof acoustic surface waves. Both simulated and experimental results demonstrate the theoretical prediction that the focusing point can be tuned lengthwise by changing the incident frequency and the lateral shifts by changing the incident angle. The results indicate that metal-like waveguide arrays can provide a feasible pathway for achieving compact and tunable sound focusing and super-resolution acoustic imaging on a subwavelength scale.
Local piezoelectric doping of monolayer WSe2
Authors: Balunov P. A. , Ankundinov A. V. , Breev I. D. , Dunaevskiy M. S. , Goltaev A. S. , Galimov A. I. , Jmerik V. N. , Likhachev K. V. , Rakhlin M. V. , Toropov A. A. , Vlasov A. S. , Mintairov A. M.
Published: May 2023

We report non-contact local doping of a monolayer WSe2 transferred onto a piezoelectric substrate having surface potential wells (SPWs) induced by structural inhomogeneities. We used epitaxial GaN and InP/GaInP2 structures, in which there are SPWs ∼0.2 V deep and 0.1–2 μm in size. Using surface topography and potential scanning probe microscopy, as well as optical reflectance, photoluminescence, and Raman spectroscopy measurements, we observed strong enhancement of charged exciton emission and Raman intensity in the SPW regions of the monolayer WSe2, which indicate on piezoelectric doping at a level n ≥ 1012 cm−2 on a length scale ∼0.2–1 μm. Our results can be used to create electron/hole quantum puddles with anyon states in transition metal dichalcogenides, promising for the development of room temperature and magnetic-field-free fault-tolerant topological quantum computing.
Paradigm gaps are associated with weird “distributional semantics” properties
Authors: Chuang Yu-Ying , Brown Dunstan , Baayen R. Harald , Evans Roger
Published: May 2023

This study investigates the phenomenon of defectiveness in Russian case and number noun paradigms from the
perspective of distributional semantics. We made use of word embeddings, high-dimensional vectors trained from large text corpora,
and compared the observed paradigms of nouns that are defective in the genitive plural, as suggested by Zaliznjak (1977), with the observed paradigms for non-defective nouns. When the embeddings of about
20,000 inflected forms were projected onto a two-dimensional space, clusters of case and number within case were found, suggesting
global semantic similarity for words with the same inflectional features. Moreover, defective lexemes were characterized by lower
semantic transparency, in that inflected forms of the same lexeme are semantically less similar to each other, and their meanings
are also more idiosyncratic. Furthermore, compared to non-defective lexemes, inflected forms from defective lexemes are further
away from the idealized average case-number meanings, obtained by averaging over the vectors of all inflected forms of the same
case-number combination. As a consequence, the semantics of defective forms are predicted less precisely by a simple model of
conceptualization that assumes that the meaning of a given Russian inflected form is approximated well by the sum of pertinent
embeddings of the lexeme, case, and number within case. We conclude that the relationship between defectiveness and semantics, at
least the kind captured by word embeddings, is stronger than has been anticipated previously.
Deconstructing imagined identities and imagined communities through humor
Authors: Gasteratou Spyridoula , Tsakona Villy
Published: May 2023

The aim of this study is to explore humor as a means for deconstructing identities in humorous narratives written
by adult L2 learners. Norton Pierce’s (1995) notions of investment in
L2 learning, imagined identities, and imagined communities as well as the concepts of
script opposition and target employed for the sociopragmatic analysis of humor (Attardo 2001) are exploited for demonstrating how humor constitutes a means for
deconstructing L2 learners’ imaginary projections and investments in L2. The analysis reveals that L2 learners use humor in their
narratives to account for their failure to fulfill their imagined identities as competent speakers and legitimate members of the
host community, or for the flouting of their expectations concerning the behavior of the members of the imagined host community.
Moreover, humor emerges as a strategy allowing learners to attenuate potential threats against their own positive face or that of
host community members (Brown and Levinson 1987).
Corpus stylistic analysis of literary translation using multilevel linguistic measures
Authors: Ryu Jisu , Kim Soonbae , Graesser Arthur C. , Jeon Moongee
Published: May 2023

Previous studies in corpus-based literary translation have tended to focus on only one or two specific aspects of
style. In this study we expand the existing analytical paradigm to show how the style inherent in source texts (STs) is reflected
in their translations. We do this using thirty-six multilevel linguistic features. The selected texts are James Joyce’s
Dubliners and A Portrait of the Artist as a Young Man and their Korean translations. We find
that the general stylistic patterns in the STs are mirrored in the target texts (TTs) in terms of several linguistic measures, but
that some aspects of style are not reflected in the TTs. The stylistic discrepancies between the STs and TTs may signify the
translator’s strategic decisions to adhere to the target language (TL) norms and translation conventions as well as to preserve
the style in the ST.
Troponin-I–induced tropomyosin pivoting defines thin-filament function in relaxed and active muscle
Authors: Lehman William , Rynkiewicz Michael J.
Published: May 2023

Regulation of the crossbridge cycle that drives muscle contraction involves a reconfiguration of the troponin–tropomyosin complex on actin filaments. By comparing atomic models of troponin–tropomyosin fitted to cryo-EM structures of inhibited and Ca2+-activated thin filaments, we find that tropomyosin pivots rather than rolls or slides across actin as generally thought. We propose that pivoting can account for the Ca2+ activation that initiates muscle contraction and then relaxation influenced by troponin-I (TnI). Tropomyosin is well-known to occupy either of three meta-stable configurations on actin, regulating access of myosin motorheads to their actin-binding sites and thus the crossbridge cycle. At low Ca2+ concentrations, tropomyosin is trapped by TnI in an inhibitory B-state that sterically blocks myosin binding to actin, leading to muscle relaxation. Ca2+ binding to TnC draws TnI away from tropomyosin, while tropomyosin moves to a C-state location over actin. This partially relieves the steric inhibition and allows weak binding of myosin heads to actin, which then transition to strong actin-bound configurations, fully activating the thin filament. Nevertheless, the reconfiguration that accompanies the initial Ca2+-sensitive B-state/C-state shift in troponin–tropomyosin on actin remains uncertain and at best is described by moderate-resolution cryo-EM reconstructions. Our recent computational studies indicate that intermolecular residue-to-residue salt-bridge linkage between actin and tropomyosin is indistinguishable in B- and C-state thin filament configurations. We show here that tropomyosin can pivot about relatively fixed points on actin to accompany B-state/C-state structural transitions. We argue that at low Ca2+ concentrations C-terminal TnI domains attract tropomyosin, causing it to bend and then pivot toward the TnI, thus blocking myosin binding and contraction.
Bearing fault feature extraction method: improved weighted envelope spectrum
Authors: Cheng Jian , Yang Yu , Wang Ping , Wang Jian , Cheng Junsheng
Published: May 2023

Many existing cyclic spectrum analysis methods are ineffective in solving bearing fault diagnosis in multi-information frequency bands. Based on this, an improved weighted envelope spectrum (IWES) method is proposed. Firstly, IWES uses the fault information intensity index to quantify bearing fault information and evaluate bearing fault information of spectral frequency bands in spectral coherence. Secondly, the threshold function is constructed to determine the threshold adaptively, so as to identify the spectrum frequency components with rich fault information in the spectral coherence. Meanwhile, a weight function is designed based on threshold function to eliminate the interference noise components and keep the fault information. Finally, the spectral coherence and weight function are used to generate IWES with multi-band information. The bearing experiments show that the IWES has excellent noise robustness and can accurately extract the bearing fault characteristic frequency.
Fault diagnosis of rotating machinery via multi-structure fusion discriminative projection
Authors: Su Shuzhi , Zhang Zhipeng , Zhu Yanmin , Hou Yakui
Published: June 2023

Rotating machinery is one of the important parts of industrial production equipment, and it is of great practical significance for fault diagnosis. Aiming at the problem of classification difficulty caused by feature interleaving in complex working conditions and high-dimension of rotating machinery fault samples, a rotating machinery fault diagnosis method based on multi-structure fusion discriminative projection (MFDP) is proposed. MFDP constructed intraclass and interclass hypergraph structures with multivariate relationships, fully revealing the higher-order association information among multiple samples. Besides, a tangential graph structure of MFDP is further constructed by combining the tangential affine of local samples to preserve the local tangential information of the manifold space. In the method, a unified objective optimization model of the discriminative hypergraph structures and local tangential graph structures is developed, and by solving the model, we can obtain fault structure features with well intraclass compactness and interclass separability. Extensive experiments on the Case Western Reserve University bearing dataset and Connecticut gear dataset show that the method has a good diagnostic accuracy of rotating machinery in different working conditions.
Topological synchronisation or a simple attractor?
Authors: Caby Théophile , Gianfelice Michele , Saussol Benoît , Vaienti Sandro
Published: May 2023

A few recent papers introduced the concept of topological synchronisation. We refer in particular to (Lahav et al 2022 Sci. Rep.
12 2508), where the theory was illustrated by means of a skew product system, coupling two logistic maps. In this case, we show that the topological synchronisation could be easily explained as the birth of an attractor for increasing values of the coupling strength and the mutual convergence of two marginal empirical measures. Numerical computations based on a careful analysis of the Lyapunov exponents suggest that the attractor supports an absolutely continuous physical measure (acpm). We finally show that for some unimodal maps such acpm exhibit a multifractal structure.
Process optimization of 4H-SiC chemical mechanical polishing based on grey relational analysis
Authors: Ban Xinxing , Duan Tianxu , Tian Zhuangzhi , Li Yunhe , Zhu Jianhui , Wang Ningchang , Han Shaoxing , Qiu Hui , Li Zhengxin
Published: May 2023

Ultra-smooth and low-damage processing of single-crystalline 4 H-SiC has become a research focus as a substrate for third-generation semiconductor wafers. However, the high hardness and strong chemical inertia significantly affect 4 H-SiC chemical-mechanical polishing (CMP) efficiency and accuracy. In this study, polishing process optimization experiments of 4 H-SiC are conducted based on the grey relational analysis method to achieve low surface roughness (Ra) and high material removal rate (MRR). First, MRR and Ra of Si surface (0001) are obtained by orthogonal experiments considering down force, rotation speed, slurry flow rate and abrasive particle size as four key factors. Then the grey relational coefficient and grey relational grade of MRR and Ra are calculated by data processing. The results show that significant factors of the single-objective process are rotation speed, down force, particle size, and flow rate, while the factors of the multi-objective process are down force, flow rate, rotation speed, and particle size in turn. Finally, the MRR of 208.12 nm h−1 and Ra of 0.391 nm are polished using multi-objective optimization process parameters. The polishing efficiency and accuracy were improved, confirming the applicability of grey relational analysis in CMP.
Change in transition balance between durable tetragonal phase and stress-induced phase of cobalt surface-layered in Bi-2212 materials by semi-empirical mechanical models
Authors: Erdem Ümit , Yildirim Gurcan , Türköz Mustafa Burak , Ülgen Asaf Tolga , Mercan Ali
Published: June 2023

This study has indicated the positive effect of sintering temperature on the mechanical durability, strength, critical stress, deformation degrees, durable tetragonal phase, failure and fracture by fatigue, and mechanical characteristic behavior to the applied test loads for the Co surface-layered Bi-2212 ceramic materials produced by the standard solid-state reaction method. The sintering mechanism has been used as the driving force for the penetration of cobalt ions in the Bi-2212 ceramic matrix. The microindentation hardness test measurements have been performed at the load intervals 0.245 N-2.940 N. The experimental findings have also been examined by the six different semi-empirical mechanical and indentation-induced cracking models. It has been found that all the mechanical performance parameters are improved considerably with increasing the diffusion sintering temperature up to 650 °C. On this basis, the Co surface-layered Bi-2212 sample produced at the sintering temperature of 650 °C has been observed to improve dramatically the mechanical durability and resistance to the applied test loads as a consequence of the formation of new force barrier regions, surface residual compressive stress regions, and slip systems in the Bi-2212 ceramic system. Similarly, the optimum sintering temperature has extensively enhanced the elastic recovery mechanism, critical stress values, and deformation degree levels, stored internal strain, and crack surface energy through the Bi-2212 ceramic materials. Accordingly, it has been noted that the best sample produced at 650 °C is more hardly broken than the other ceramics. Namely, the optimum sintering temperature has decreased the sensitivity to the applied test loads as a result of delaying the beginning of the plateau limit regions. On the other hand, all the mechanism has been found to reverse completely depending on the excess sintering temperature. Lastly, the indentation-induced cracking model has been found to exhibit the closest results to the original Vickers microhardness parameters in the plateau limit regions.
The Dirac equation with
PT
/non-
PT
-symmetric potentials in curved spacetime backgrounds
Authors: Yeşiltaş Özlem , Imane Kouachi Ikram
Published: June 2023

In this paper, we have presented the Dirac equation in the frame of position-dependent mass on two dimensional gravitational static background in the presence of




/non-




-symmetric potential interactions. The exponential metric component have formed the reduced Dirac operator into the general supersymmetric model within mass changing with coordinates. We have obtained the eigenvalues of the Dirac operator for the complex Morse and trigonometric complex Scarf-II potentials SL(2, C) using Lie algebras and the supersymmetric quantum mechanical approaches. Moreover, after obtaining a general Sturm-Liouville type equation using a convenient mapping, the system have become available to be investigated within η- pseudo-Hermiticity. With this context, η operator is found for the examples of complex trigonometric Rosen-Morse potential and complex Morse potentials with real and complex parameters of the initial system and finally the solutions are obtained for each model with the graphics of energy values and probability densities.
Giant and controllable Goos–Hänchen shift of a reflective beam off a hyperbolic metasurface of polar crystals
Authors: Xue 薛 Tian 天 , Li 李 Yu-Bo 宇博 , Song 宋 Hao-Yuan 浩元 , Wang 王 Xiang-Guang 相光 , Zhang 张 Qiang 强 , Fu 付 Shu-Fang 淑芳 , Zhou 周 Sheng 胜 , Wang 王 Xuan-Zhang 选章
Published: June 2023

We conduct a theoretical analysis of the massive and tunable Goos–Hänchen (GH) shift on a polar crystal covered with periodical black phosphorus (BP)-patches in the THz range. The surface plasmon phonon polaritons (SPPPs), which are coupled by the surface phonon polaritons (SPhPs) and surface plasmon polaritons (SPPs), can greatly increase GH shifts. Based on the in-plane anisotropy of BP, two typical metasurface models are designed and investigated. An enormous GH shift of about −7565.58λ
0 is achieved by adjusting the physical parameters of the BP-patches. In the designed metasurface structure, the maximum sensitivity accompanying large GH shifts can reach about 6.43 × 108
λ
0/RIU, which is extremely sensitive to the size, carrier density, and layer number of BP. Compared with a traditional surface plasmon resonance sensor, the sensitivity is increased by at least two orders of magnitude. We believe that investigating metasurface-based SPPPs sensors could lead to high-sensitivity biochemical detection applications.
Cortical layering disrupts multi-electrode current steering
Authors: Meikle Sabrina J , Hagan Maureen A , Price Nicholas S C , Wong Yan T
Published: June 2023

Abstract

Objective. Blindness affects approximately 40 million people worldwide and has inspired the development of cortical visual prostheses for restoring sight. Cortical visual prostheses electrically stimulate neurons of the visual cortex to artificially evoke visual percepts. Of the 6 layers of the visual cortex, layer 4 contains neurons that are likely to evoke a visual percept. Intracortical prostheses therefore aim to target layer 4; however, this can be difficult due to cortical curvature, inter-subject cortical variability, blindness-induced anatomical changes in cortex, and electrode placement variations. We investigated the feasibility of using current steering to stimulate specific cortical layers between electrodes in the laminar column. Approach. We explored whether the multiunit neural activity peak can be manipulated between two simultaneously stimulating electrodes in different layers of the cortical column. A 64-channel, 4-shank electrode array was implanted into the visual cortex of Sprague–Dawley rats (n = 7) orthogonal to the cortical surface. A remote return electrode was positioned over the frontal cortex in the same hemisphere. Charge was supplied to two stimulating electrodes along a single shank. Differing ratios of charge (100:0, 75:25, 50:50) and separation distances (300–500 μm) were tested. Results. Current steering across the cortical layers did not result in a consistent shift of the neural activity peak. Both single-electrode and dual-electrode stimulation induced activity throughout the cortical column. This contrasts observations that current steering evoked a controllable peak of neural activity between electrodes implanted at similar cortical depths. However, dual-electrode stimulation across the layers did reduce the stimulation threshold at each site compared to single-electrode stimulation. Significance. Multi-electrode stimulation is not suitable for targeted activation of layers using current steering. However, it can be used to reduce activation thresholds at adjacent electrodes within a given cortical layer. This may be applied to reduce the stimulation side effects of neural prostheses, such as seizures.
The power dependence of the maximum achievable H-mode and (disruptive) L-mode separatrix density in ASDEX Upgrade
Authors: Manz P. , Eich T. , Grover O.
Published: May 2023

In future fusion reactors disruptions must be avoided at all costs. Disruptions due to the density limit (DL) are typically described by the power-independent Greenwald scaling. Recently, a power dependence of the disruptive DL was predicted by several authors (Zanca et al 2019 Nucl. Fusion
59 126011; Giacomin et al 2022 Phys. Rev. Lett.
128 185003; Singh and Diamond 2022 Plasma Phys. Control. Fusion
64 084004; Stroth et al 2022 Nucl. Fusion
62 076008; Brown and Goldston 2021 Nucl. Mater. Energy
27 101002). It is investigated whether this increases the operational range of the tokamak. Increasing the heating power in the L-mode can induce an L-H transition, and therefore a power-dependent DL and the L-H transition cannot be considered independently. The different models are tested on a data base for separatrix parameters at the separatrix of ASDEX Upgrade and compared with the concept (SepOS) presented in Eich and Manz (2021 Nucl. Fusion
61 086017). The disruptive separatrix density scales with the power

n

e

∝

P

0.38
±
0.08

in good agreement to all models. Also the back transition from high to low (H-L) confinement shows an approximately Greenwald scaling with an additional power dependence

n

e

∝

P

0.4

according to the SepOS concept. For future devices operating at much higher heating power such a power scaling may allow operation at much higher separatrix densities than are common in H-mode operation. Preconditions to extrapolation for future devices are discussed.
Neutrinos: The messengers of the invisible world
Authors: Vannucci F
Published: June 2023

A short story on a few aspects of neutrinos (neutrino oscillations and the possibility of a sterile neutrino) for the Anniversary Session of the 10th international symposium on “Large TPCs for low-energy rare event detection”.
Boundary-layer aerodynamics over long wind farms over hilly terrains
Authors: Segalini Antonio
Published: May 2023

A wind-tunnel campaign with a wind-farm model over two cosinusoidal hills has been performed to assess the changes in the flow above a wind-farm model in presence of topography. The experiments focused on the three-dimensional velocity field above the turbines to characterise the boundary layer evolution along the farm. The flow over the hills was characterised first without the turbines and compared with potential flow theory with good agreement between the two. The presence of the turbines imposed an upward displacement of the velocity field with similar speed-ups on the hill crests as observed in absence of turbines. The vertical velocity was also quite similar in the windward side of the hills and significantly damped in the leeward side, probably due to boundary-layer separation and shear sheltering operated by the turbine top tips. The presence of free-stream turbulence does not change this qualitative picture, although the turbulent activity within the internal boundary layer is slightly increased. The analysis of the streamwise velocity spectra indicated the emergence of the wake meandering as dominant dynamics and its modulation operated by the topography.
Cross-code verification of non-neutral ABL and single wind turbine wake modelling in LES
Authors: Hodgson E L , Souaiby M , Troldborg N , Porté-Agel F , Andersen S J
Published: May 2023

Large Eddy Simulations (LES) of atmospheric boundary layer (ABL) flow with the actuator disc (AD) for turbine modelling is a widely used method of simulating wind farm flows. Hence, it is important to understand the requirements for achieving a good comparison between ABL flow and turbine wakes between different research group setups, despite unavoidable differences which include LES numerical framework, sub-grid scale (SGS) model, and turbine modelling, and at grid resolutions achievable in large wind farm simulations. In this work, conventionally neutral (CNBL), stable (SBL) and convective (CBL) boundary layers, and single turbine wakes under these different conditions, are compared between the EPFL pseudo-spectral code WIRE LES and the DTU finite-volume code EllipSys3D. ABL profiles largely agree well with hub height velocity magnitudes agreeing to 0.7%, 3.8% and 0.5% for the CNBL, SBL and CBL respectively. The scale-dependent SGS model of WIRE LES results in reduced grid dependency, while EllipSys3D required higher grid resolution in the SBL. Wake flows show improved wake recovery and greater added turbulence intensity with increasing grid resolution, and good agreement is achieved with a radius R to cell size ratio of R/(dxdydz)1/3 ≥ 6.5. Trends in wake flow with different stability conditions, such as the influence of inflow turbulence intensity or shear, are well replicated between codes. Likewise, wake deficit and added TI profiles, and distributions of turbine power and thrust also agree well. Mean power output predictions match to 4.3%, 7.2% and 3.8% in the CNBL, SBL and CBL respectively between the two codes. Overall, these results demonstrate that good agreement is possible with aligned turbine data and sufficient grid resolution.
High-resolution satellite observations to account for coastal gradient in wind resource assessment: application to French coastal areas
Authors: Cathelain M. , Husson R. , Berger H. , Fragoso M.
Published: May 2023

The 18-year database of European Synthetic Aperture Radars (SAR) provides worldwide surface wind measurements at one-kilometre resolution. Through an innovative vertical extrapolation methodology published in 2022, these long-term, wide, and high-resolution observations can complement in-situ observations and mesoscale modelling for offshore wind resource assessment. The methodology is based on four steps: (i) derivation of the 10-min SAR surface winds from SAR sea surface roughness, (ii) a site- and time-independent machine learning algorithm based on a large buoy network to correct SAR winds due to biases inherent to the characteristics of the satellite sensors and wind retrieval methodology, (iii) extrapolation up to a few hundred meters based on a second machine learning algorithm trained with in-situ observations and physical parameters from a high-resolution mesoscale model related to e.g. atmospheric stability, and (iv) a final post-processing step to correct for low temporal sampling of the SAR database (a couple of days in Europe for one satellite) and retrieve wind statistics. The resulting output is a 1-km resolution wind atlas in a large (> 3000 km2) offshore and/or coastal area where strong coastal gradients will be accounted for. It can also integrate directly the estimation of the extractible wind power. Here, an improvement of the extrapolation method is presented and applied to a French offshore area in South Brittany. The wind atlas obtained with SAR is found to display a much finer level of details and estimate more precisely the coastal gradient.
Wind turbine wake: bridging the gap between large eddy simulations and wind tunnel experiments
Authors: Gillyns E. , Buckingham S. , van Beeck J. , Winckelmans G.
Published: May 2023

The wind industry has experienced rapid growth over the past two decades and wind energy is expected to continue leading the way in the global energy transition. Additional wind farms are expected to be installed in the coming years, both offshore and onshore. In view of exploiting any suitable terrain, an increased number of turbines are installed in close proximity to existing structures, thus exposing these to the wake turbulence. For instance, electrical cables are regularly exposed to those higher levels of turbulence compared to design loads, potentially leading to premature failure of the power line. It is hence essential to have a good understanding of these phenomena to be able to mitigate their effects. Scale-resolving investigations using Large Eddy Simulation (LES) can provide insight into site-specific loading conditions when combined with an Actuator Line Model (ALM), which reproduces the reaction force of each blade on the flow while still using a relatively coarse grid. The ALM used in this framework was newly-implemented in the spectral element code Nek5000, a highly efficient code with reduced cost per degree of freedom and exponentially fast convergence. The present work aims to bridge the gap between LES and a well controlled wind tunnel test of a scaled wind turbine, for validation purposes.

First, a small scale wind turbine of diameter 80 cm is designed and tested in a well controlled wind tunnel environment. Experimental data are gathered ahead of it and in its wake, and the mean velocity and turbulence intensity profiles are presented.

Although blockage effects are kept to a minimum, they will be accounted for in the simulations to ensure a better comparison with the measurements. In this work, we focus on a single inflow velocity field and on a fixed rotation speed.

Simulating the produced wake using LES combined with ALM remains challenging as the results are very sensitive to the turbulent inflow conditions and also to the airfoil aerodynamics used in the ALM. In the experiment, the incoming profile is also that of a developing flow and accurately reproducing its main characteristics is required for proper inflow to the LES. A “Recycle and Rescale Method” (R2M) will be hence be used as it is well suited for such case. The method will allow for the relevant turbulent boundary layer structures to be properly reproduced numerically, hence ensuring that the wind turbine is exposed to similar inflow conditions than in the experiment.

With the developed framework, the comparison between the wake produced in the experiment and that obtained using LES with ALM will provide the necessary data to further adjust the parameter and grid size used for the LES and the polar model used in the ALM.
Impact of the rotor blades elasticity on the loads and wake of the large IEA 15-MW wind turbine
Authors: Trigaux Francois , Chatelain Philippe , Winckelmans Grégoire
Published: May 2023

This work presents an investigation of the aeroelastic effects occurring on the IEA 15-MW reference wind turbine in a turbulent atmospheric boundary layer. Large Eddy simulation is carried out using an actuator line method coupled to the finite element beam solver BeamDyn. The results show that the blades experience significant displacements, leading to an important variation of the loads along the blade span. The turbulence also interacts with the blades natural frequencies, resulting in a variation of the spectra of the various loads. The impact of the flexibility is also evaluated on the wake by comparing the undeformed configuration with a statically and dynamically deformed rotor. It appears that the mean deformation plays an important role in the wake development due to changes in the load distribution, but that the dynamic effects have minimal impact on the wake behavior.
Wake interactions behind individual-tower multi-rotor wind turbine configurations
Authors: Brown K. , Cheung L. , Hsieh A. , Maniaci D. , Hamilton W.
Published: May 2023

Multiple rotors on single structures have long been proposed to increase wind turbine energy capture with no increase in rotor size, but at the cost of additional mechanical complexity in the yaw and tower designs. Standard turbines on their own very-closely-spaced towers avoid these disadvantages but create a significant disadvantage; for some wind directions the wake turbulence of a rotor enters the swept area of a very close downwind rotor causing low output, fatigue stress, and changes in wake recovery. Knowing how the performance of pairs of closely spaced rotors varies with wind direction is essential to design a layout that maximizes the useful directions and minimizes the losses and stress at other directions. In the current work, the high-fidelity large-eddy simulation (LES) code Exa-Wind/Nalu-Wind is used to simulate the wake interactions from paired-rotor configurations in a neutrally stratified atmospheric boundary layer to investigate performance and feasibility. Each rotor pair consists of two Vestas V27 turbines with hub-to-hub separation distances of 1.5 rotor diameters. The on-design wind direction results are consistent with previous literature. For an off-design wind direction of 26.6°, results indicate little change in power and far-wake recovery relative to the on-design case. At a direction of 45.0°, significant rotor-wake interactions produce an increase in power but also in far-wake velocity deficit and turbulence intensity. A severely off-design case is also considered.
LiDAR Measurements to Investigate Farm-to-Farm Interactions at the AWAKEN Experiment
Authors: Puccioni Matteo , Iungo Giacomo Valerio , Moss Coleman , Solari Mojtaba Shams , Letizia Stefano , Bodini Nicola , Moriarty Patrick
Published: May 2023

The exponential growth of wind energy and the need to exploit wind resources over areas with higher energy potential have led to the construction of neighboring wind turbines and farms with relatively small separation distances. As a result, for specific wind and atmospheric conditions, the wakes generated by an upstream wind farm may affect wind resources available for a downstream wind farm resulting in detrimental impacts on energy harvesting and structural loads for the downwind wind turbines. Distances between neighboring wind farms are typically larger than those associated with intra-wind-farm wake interactions, generating cumulative wakes whose characteristics might differ from those predicted through classical engineering wake models. These phenomena are referred to as farm-to-farm interactions. A better understanding and characterization of farm-to-farm interactions is one of the science goals tackled by the ongoing American WAKE experimeNt (AWAKEN). The site under investigation for this field campaign comprises two large wind farms in northern Oklahoma, USA, which are spaced roughly 5km apart along the prevailing South-North wind direction. To investigate possible interactions between these two wind farms, the WindFluX mobile LiDAR station has been deployed mainly to perform volumetric scans over their gap region. In this paper, preliminary results from these LiDAR volumetric scans will be discussed, specifically for a case with multiple wind turbine wakes evolving during the occurrence of a low-level jet.
Overview of recent observations and simulations from the American WAKE experimeNt (AWAKEN) field campaign
Authors: Moriarty Patrick , Bodini Nicola , Cheung Lawrence , Hamilton Nicholas , Herges Thomas , Kaul Colleen , Letizia Stefano , Pekour Mikhail , Simley Eric
Published: May 2023

The American WAKE experimeNt (AWAKEN) is a large-scale field campaign focused on gathering new detailed observations of wind farm–atmosphere interactions for improved understanding of wind farm physics and overall performance. The field campaign, centered around five wind farms in northern Oklahoma, began in September 2022 and will run through at least October 2023. This paper summarizes some of the initial observations and simulations performed as part of the AWAKEN project.
Physics informed neural networks for wind field modeling in wind farms
Authors: Cobelli P. , Shukla K. , Nesmachnow S. , Draper M.
Published: May 2023

This article presents an approach for applying Physics-Informed Neural Networks (PINNs) for modeling wind fields in wind farms. The addressed problem is reconstructing the inflow velocity field for a wind turbine. Several PINN variants are implemented and validated over a real-world case study, trained with sparse numerically simulated velocity data. Results demonstrate that the proposed PINNs can accurately assimilate the numerical simulation data, and compute accurate solutions. The proposed approach is a viable alternative for modeling wind fields in wind farms, requiring significantly lower execution times than standard numerical/simulation methods.
Exploring cooperation between wind farms: a wake steering optimization study of the Belgian offshore wind farm cluster
Authors: Foloppe B , Dewitte L , Munters W
Published: May 2023

In recent years, significant research efforts have focused on increasing power extraction using wake steering through yaw misalignment. In the current work, we evaluate the potential increase in annual energy production (AEP) for the Belgian offshore wind farm cluster using the FLORIS framework. The 2.2 GW Belgian cluster is an excellent test case to explore cooperation between wind farms as the concession zone is split into nine individual farms, resulting in a mix of intra- and inter-farm wakes to be considered in one of the largest wind farm clusters operational to date. Furthermore, the cluster high power density with relatively low turbine spacings is found to be responsive to wake mitigation strategies. Three different cost functions are compared. The first one is the complete cluster yaw angles optimization. The other two are farm-based optimizations seeking to maximize either their own AEP or the cluster AEP. Results show that all wind farms benefit from every optimization, encouraging operators to implement this strategy. The cluster optimization is found to be the one providing the best AEP increase for all wind farms individually and thus for the cluster. The farm-based function optimizing the cluster AEP is in second place, encouraging wind farm operators to collaborate for their own profits.