bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resonant or asymmetric: the status of sub-GeV dark matter
Authors: Balan Sowmiya , Balázs Csaba , Bringmann Torsten , Cappiello Christopher , Catena Riccardo , Emken Timon , Gonzalo Tomás E. , Gray Taylor R. , Handley Will , Huynh Quan , Kahlhoefer Felix , Vincent Aaron C. 
Published: January 2025

Abstract
Sub-GeV dark matter (DM) particles produced via thermal freeze-out evade many of the strong constraints on heavier DM candidates but at the same time face a multitude of new constraints from laboratory experiments, astrophysical observations and cosmological data. In this work we combine all of these constraints in order to perform frequentist and Bayesian global analyses of fermionic and scalar sub-GeV DM coupled to a dark photon with kinetic mixing. For fermionic DM, we find viable parameter regions close to the dark photon resonance, which expand significantly when including a particle-antiparticle asymmetry. For scalar DM, the velocity-dependent annihilation cross section evades the strongest constraints even in the symmetric case. Using Bayesian model comparison, we show that both asymmetric fermionic DM and symmetric scalar DM are preferred over symmetric fermionic DM due to the reduced fine-tuning penalty. Finally, we explore the discovery prospects of near-future experiments both in the full parameter space and for specific benchmark points.
We find that the most commonly used benchmark scenarios are already in tension with existing constraints and propose a new benchmark point that can be targeted with future searches.
Merging and separation of polarization singularities in complex lattices
Authors: Wang Mengyao , Shi Tian , Ning Luhui , Liu Peng , Li Liangsheng , Zheng Ning 
Published: January 2025

Abstract
Bound states in the continuum (BICs) and circularly polarized states (CPSs), as far-field polarization singularities, by controlling geometric parameters of photonic crystals, exhibit their evolution in momentum space that can be observed. This offers significant potential in optics and photonics. Here, we reveal that in complex lattices, far-field polarization singularities can be flexibly manipulated while preserving structural symmetry. The change of the topological charge for the at-Γ BIC can generate new BICs or CPSs. At an off-Γ point, a BIC can spawn from the collision of two CPSs. As the structure thickness increases, this BIC will meet the at-Γ BIC. The merging of BICs can induce the topological charge transition and yield a large wavevector space around Γ point with ultrahigh quality (Q) factors. Our findings provide a novel degree of freedom for manipulating polarization singularities, which holds great promise in radiation modulation and singular optics.
Optimizing the proportion of stimulation area in a grid stimulus for user-friendly SSVEP-based BCIs
Authors: Gu Meng , Pei Weihua , Gao Xiaorong , Wang Yijun 
Published: January 2025

Abstract

Objective. Steady-state visual evoked potentials (SSVEPs) rely on the photic driving response to encode electroencephalogram (EEG) signals stably and efficiently. However, the user experience of the traditional stimulation with high-contrast flickers urgently needs to be improved. In this study, we introduce a novel paradigm of grid stimulation with weak flickering perception, distinguished by a markedly lower proportion of stimulation area in the overall pattern. Approach. In an offline single-target experiment, we investigated the unique characteristics of SSVEPs evoked by varying proportions in grid stimuli within low and medium frequency bands. Based on the analysis of simulation performance across a four-class brain–computer interface (BCI) task and the evaluation of user experience questionnaires, a subset of paradigms that balance performance and comfort were selected for implementation in four-target online BCI systems. Main results. Our results demonstrate that even ultra-low stimulation proportion paradigms can still evoke strong responses within specific frequency bands, effectively enhancing user experience with low and middle frequency stimuli. Notably, proportions of 0.94% and 2.10% within the 3–5 Hz range provide an optimal balance between performance and user experience. For frequencies extending up to 15 Hz, a 2.10% proportion remains ideal. At 20 Hz, slightly higher proportions of 3.75% and 8.43% maintain these benefits. Significance. These findings are crucial for advancing the development of effective and user-friendly SSVEP-based BCI systems.
Effects of helium irradiation damage on deuterium plasma-driven permeation through tungsten coated RAFM steel
Authors: Xu Yue , Tian Xiao-Ping , Tan Hong-Yan , Fu Hai-Ying , Ni Jun-Jie , Luo Lai-Ma , Wu Yu-Cheng 
Published: January 2025

Abstract
In future fusion reactors, the first wall will be irradiated with hydrogen fuel (deuterium (D), tritium (T)) and helium (He) with low energies. In this work, the effects of He plasma irradiation on D permeation through tungsten (W) coated reduced activation ferritic/martensitic (RAFM) steel were systematically investigated by performing plasma-driven permeation (PDP) measurements in the temperature range of 523–833 K. The W coatings were prepared by magnetron sputtering. He plasma irradiation with different fluences was carried out in a linear plasma device. The results showed that as He irradiation fluence increased, the surface damage of W coatings intensified, resulting in a high steady-state D-PDP flux and effective diffusion coefficient. The effect of incident ion energy on D-PDP was also influenced by He pre-irradiation. After He irradiation with a fluence of 6.0 × 1024 He m−2, the D-PDP flux was found to decrease with increasing incident ion energy despite the fact that the sample temperature was gradually increasing. The He pre-damage affected the overall D transport by re-balancing the bulk diffusion and surface recombination processes, therefore determining the PDP flux. D-PDP through W + RAFM under simultaneous D + He mixture plasma exposure was studied as well. The results indicated that the presence of He reduced the ionization rate of the D plasma and decreased D-PDP flux. D-PDP regime under the mixture plasma exposure was verified by calculating the transport parameter. It was found that the D-PDP regime was not changed by He introduction, which remained in the RD regime (recombination-limited D release from upstream surface and diffusion-limited D release from downstream surface).
Hybrid hydrogen-electricity production using spherical tokamaks: a cost-driver sensitivity study and techno-economic analysis
Authors: Hidalgo-Salaverri J. , Griffiths T. , Xuereb Conti Z. , Cano-Megias P. , Chacartegui R. , Bluck M. , Ayllon-Guerola J. , Mancini A. , Garcia-Munoz M. , Viezzer E. 
Published: January 2025

Abstract
Hybrid fusion power plants, which produce both hydrogen and electricity, are proposed as a way to decarbonise the fossil-fuel-dominated primary energy market and improve plant economics. The main cost drivers of a fusion power plant based on a spherical tokamak have been identified using statistical analysis (Morris and Sobol methods) from a wide range of cases obtained with the systems code PROCESS. The analysis reveals the importance of plasma physics and reactor geometry on power plant economics. Three scenarios of advancing technophysical assumptions (conservative, moderate and optimistic) have been chosen to study the integration of the fusion reactor with the power block (Rankine, He-Brayton or super-critical-CO2-Feher) and with the PEM electrolyser. The super-critical-CO2 cycle returns the best results for the studied temperature range (500 ∘C–800 ∘C), with an efficiency between 40%–56%. The modelled PEM is in line with current commercial models with a consumption of 51.97 kWh kg−1 H2. The economic feasibility of these scenarios has been explored for a set of learning factors that consider the cheapening of the capital costs tied to experience. The LCOE of these scenarios have been compared against current price ranges of solar, wind and fission power and the LCOH against PEM prices, showing that the moderate and optimistic scenarios could be competitive for learning factors lower than 0.5 and capacity factors larger than 0.7. An extrapolation of the optimistic scenario shows that the hybrid fusion power plant in the French and German market can improve the plant profits by 15% and 66% respectively.
A continental approach to estimate the area required for proposed wind-power parks and their overlap with protected areas in Africa
Authors: Mayer Jana , Peters Rebecca , Bange Jens , Mauz Moritz , Platis Andreas , Zarfl Christiane 
Published: January 2025

Abstract
Wind energy (WE) is one of the key renewable energy technologies required to transform the energy sector to reduce climate change. In the global expansion of WE, one main concern is that wind-power parks (WPPs) take up large areas of land, causing conflicts with other uses such as nature conservation. Existing impact analyses for WPPs are mostly restricted to case studies, and it lacks studies that investigate potential impacts at a larger scale because no scientific consensus on the area associated to a WPP exists. This study proposes a continental, GIS-based approach to estimate the area required for proposed onshore WPPs and to estimate their potential overlap with protected areas (PAs) on the African continent. The results of the spatial analysis show that, in total, the currently proposed 149 WPPs would require 852 km2 of land on the African continent, thereof 11 would overlap with PAs. The overlaps sum up to an area of 42 km2, which corresponds to an affected nominal power of 834 MW (5% of the total projected wind power capacity). These findings reveal the need for further purposefully local in-depth analyses to investigate if the WPP can be operated in accordance with the conservation of the PA. This work provides new data and a transferable methodological approach on the expansion of WE and its potential space requirement and contributes to the investigation of potential land-use conflicts of proposed onshore WPPs on a broader scale.
Land conversions not climate effects are the dominant indirect consequence of sun-driven CO2 capture, conversion, and sequestration
Authors: Adam Moritz , Kleinen Thomas , May Matthias M , Rehfeld Kira 
Published: January 2025

Abstract
Removing carbon dioxide (CO2) from the atmosphere is required for mitigating climate change. Large-scale direct air capture combined with injecting CO2 into geological formations could retain carbon long-term, but demands a substantial amount of energy, pipeline infrastructure, and suitable sites for gaseous storage. Here, we study Earth system impacts of modular, sun-powered process chains, which combine direct air capture with (electro)chemical conversion of the captured CO2 into liquid or solid sink products and subsequent product storage (sDACCCS). Drawing on a novel explicit representation of CO2 removal in a state-of-the-art Earth system model, we find that these process chains can be renewably powered and have minimal implications for the climate and carbon cycle. However, to stabilize the planetary temperature two degrees above pre-industrial levels, CO2 capturing, conversion, and associated energy harvest demand up to 0.46% of the global land area in a high-efficiency scenario. This global land footprint increases to 2.82% when assuming present-day technology and pushing to the bounds of removal. Mitigating historical emission burdens within individual countries in this high-removal scenario requires converting an area equivalent to 40% of the European Union’s agricultural land. Scenarios assuming successful technological development could halve this environmental burden, but it is uncertain to what degree they could materialize. Therefore, ambitious decarbonization is vital to reduce the risk of land use conflicts if efficiencies remain lower than expected.
Generalized Siklos space-times
Authors: Araneda Bernardo , Murcia Ángel J 
Published: January 2025

Abstract
Motivated by supersymmetry methods in general relativity, we study four-dimensional Lorentzian space-times with a complex Dirac spinor field satisfying a Killing-spinor-like equation where the Killing constant is promoted to a complex function. We call the resulting geometry a generalized Siklos space-time. After deriving a number of identities for complex spaces, we specialize to Lorentz signature, where we show that the Killing function must be real and that the corresponding Dirac spinor is Majorana (as long as the space-time is not conformally flat), and we obtain the local form of the metric. We show that the purely gravitational degrees of freedom correspond to waves, whereas the matter sources generically correspond, via Einstein’s field equations, to a sum of pure radiation and a space-like perfect fluid. Consequently, we conclude that the physically relevant case is obtained when the Killing function is homogeneous on the wave surfaces.
Localization in quantum field theory for inertial and accelerated observers
Authors: Falcone R , Conti C 
Published: January 2025

Abstract
We study the problem of localization in quantum field theory (QFT) from the point of view of inertial and accelerated experimenters. We consider the Newton–Wigner, the algebraic QFT (AQFT) and the modal localization schemes, which are, respectively, based on the orthogonality condition for states localized in disjoint regions of space, on the algebraic approach to QFT and on the representation of single particles as positive frequency solution of the field equation. We show that only the AQFT scheme obeys causality and physical invariance under diffeomorphisms. Then, we consider the nonrelativistic limit of quantum fields in the Rindler frame. We demonstrate the convergence between the AQFT and the modal scheme and we show the emergence of the Born notion of localization of states and observables. Also, we study the scenario in which an experimenter prepares states over a background vacuum by means of nonrelativistic local operators and another experimenter carries out nonrelativistic local measurements in a different region. We find that the independence between preparation of states and measurements is not guaranteed when both experimenters are accelerated and the background state is different from Rindler vacuum, or when one of the two experimenters is inertial.
Polarization-dependent vibrational strong coupling in a metamaterial
Authors: Dayal Govind 
Published: January 2025

Abstract
We report on polarization-dependent strong coupling between vibrational transitions and the electromagnetic mode of a molecule-embedded metamaterial cavity. The metamaterial cavity comprises a modified tri-layer structure of metal-insulator-metal, where the insulating layer is replaced by an infrared-active polymer. This polymer layer is sandwiched between an array of linear antennae on top and a continuous metal film at the bottom where the maximum field enhancement occurs. Using polarization-selective reflectivity simulation of the cavity, we analyze their response to different light polarization and find two orthogonally polarized optical systems with different coupling strengths, one strongly coupled and one weakly coupled. The strong coupling gives rise to the formation of lower and upper polaritons, while dark states emerge because of weak coupling. This ultrathin metamaterial with tunable properties can pave the way for developing active, dynamic, tunable infrared polaritonic devices, molecular sensors, site-selective chemical reaction control, and quantum information processing.
Feature Characterization for Profile Surface Texture
Authors: Müller Alexander , Eifler Matthias , Jawaid Arsalan , Seewig Joerg 
Published: January 2025

Abstract
Conventional field parameters for surface measurement use all data points, while feature characterization focuses on subsets extracted by watershed segmentation. This approach enables the extraction of specific features that are potentially responsible for the function of the surface or are a direct reflection of the manufacturing process, allowing for a more accurate assessment of both aspects. Feature characterization with the underlying watershed segmentation for areal surface topographies has been standardized for over a decade and is well established in industry and research. In contrast, feature characterization for surface profiles has been standardized recently, and the corresponding standard for watershed segmentation is planned to be published in the near future. Since the standards do not provide guidelines for implementation, this paper presents an unambiguous algorithm of the watershed segmentation and the feature characterization for surface profiles. This framework provides the basis for future work, mainly investigating the relationship between feature parameters based on feature characterization and the function of the surface or manufacturing process. For this purpose, recommendations for the configuration and extensions of the toolbox can also be developed, which could find their way into the ISO standards.
Study on improving tribological properties of brush/ring current carrying based on anodic oxidation
Authors: Li Chenshi , Zhao Xinze , Lv Yaru , Ying Rushu , Zhao Meiyun 
Published: January 2025

Abstract
Surface corrosion of the collector ring is an important factor that affects the current-carrying characteristics of the brush/ring system. A suitable surface film can effectively enhance the corrosion resistance of the surface and improve the tribological characteristics of the current-carrying ring. This paper focuses on the collector ring in the brush/ring current-carrying system of a hydrogenerator as the research object. Under the conditions of an anodic oxidation test with a current density of 0.004 A cm−2, optimized as the anodic oxidation technology, a surface film was formed by selecting oxidation times of 3, 5, 10, and 15 min (short duration, low current). The characteristics of the film were measured and analyzed using XPS, AFM, and SEM. Current-carrying tribological tests were conducted on a brush/ring current-carrying wear tester, and the relationship between surface film characteristics, polarization curves, and impedance spectra under different oxidation conditions was analyzed using an electrochemical device. The results show that, as oxidation time increases, the oxide film transitions from a dense barrier layer to a porous oxide film, with both the thickness of the oxide layer and the oxygen content in the film increasing. The wear mechanism evolves from ‘three-body’ wear to ‘two-body’ wear, and eventually to arc wear. An oxidation time of 10 min provides the best current-carrying performance, with a contact resistance of 1.118Ω and a friction coefficient of 0.2643. An oxidation time of 3 min offers the best corrosion resistance, with a maximum self-corrosion potential of −0.8784 V and a minimum corrosion current density of 3.872 × 10−6 A cm−2. The anodic oxide film effectively protects the collector ring from external corrosive factors, extending its service life. Additionally, it reduces friction and contact resistance to some extent, ensuring the long-term stable operation of the equipment in harsh environments.
A novel method of MPPT of photovoltaic power generation system based on MSINGO
Authors: Li Jie , Shan Yingge , Li Jinjun , Qi Shancheng , Wang Qi , Wang Dantong , Hu Yongtao 
Published: January 2025

Abstract
The speed and accuracy of Maximum Power Point Tracking (MPPT) have a significant impact on photovoltaic power generation. In this paper, a novel method is proposed for fast and accurate MPPT of photovoltaic power generation systems. First, the Northern Goshawk Optimization algorithm (NGO) is introduced in the MPPT. Second, a multi strategy is applied to improve the NGO, and MSINGO is proposed. In the MSINGO algorithm, the optimal individual leadership strategy enhances the optimization accuracy and convergence speed, the enhanced Levy flight strategy leads it to escape from the local optimum, and the pinhole imaging learning strategy guides the population towards the global optimum. Finally, MSINGO was applied to MPPT, and a simulation analysis of a single photovoltaic module and photovoltaic array under different working conditions was conducted and compared with other intelligent optimization algorithms. The results show that the proposed method can achieve MPPT with minimal time consumption and better tracking efficiency.
AtOMICS: A deep learning-based Automated Optomechanical Intelligent Coupling System for testing and characterization of silicon photonics chiplets
Authors: Flor Flores Jaime , Solomon Jim , Nasseraddin Connor , Yerebakan Talha , Matsko Andrey B. , Wong Chee Wei 
Published: January 2025

Abstract
Recent advances in silicon photonics promise to revolutionize modern technology by improving performance of everyday devices in multiple fields [1]. However, as the industry moves into a mass fabrication phase, the problem of effective testing of integrated silicon photonics devices remains to be solved. A cost-efficient manner that reduces schedule risk needs to involve automated testing of multiple devices that share common characteristics such as input-output coupling mechanisms, but at the same time needs to be generalizable to multiple types of devices and scenarios. In this paper we present a neural network-based automated system designed for in-plane fiber-chip-fiber testing, characterization, and active alignment of silicon photonic devices that use process-design-kit library edge couplers. The presented approach combines state-of-the-art computer vision techniques with time-series analysis, in order to control a testing setup that can process multiple devices and can be easily tuned to incorporate additional hardware. The system can operate at vacuum or atmospheric pressures and maintains stability for fairly long time periods in excess of a month.&#xD;
Influence of large-scale atmospheric circulation and Mediterranean sea surface temperature to extreme land precipitation: the case of storm Alex
Authors: Terray Laurent , Bador Margot 
Published: January 2025

Abstract
Extreme (greater than 500 mm) amount of rain fell in southeastern France and northern Italy on 2nd and 3rd October 2020 during a ‘Mediterranean episode’ triggered by the powerful extratropical cyclone Alex. Here we use a dynamical adjustment methodology based on constructed analogues to assess the contributions of different drivers to the magnitude of this extreme precipitation event. We first show that the mean effect of the observed atmospheric circulation pattern, an intense low-pressure system centered over the coasts of Western Europe associated with a cold pool and a secondary low-pressure system, can explain about 80% of the precipitation event magnitude. By contrasting the effect of Alex atmospheric circulation with an anomalously warm Mediterranean sea and eastern Atlantic ocean versus neutral sea surface temperature (SST) conditions, we show that the influence of September 2020 positive SST anomalies can explain a large fraction of the 20% residual precipitation over southeastern France and northern Italy. Finally, based on a storyline approach, we find that the dynamic component, the atmospheric circulation contribution to the extreme precipitation event, was more extreme than it would have been, had it occurred during the mid-20th century. The increase in the magnitude of the dynamic component since 1950 follows a Clausius–Clapeyron scaling, in agreement with previous studies about the intensity changes of Mediterranean extreme precipitation episodes. (limit = 300 words).