bluuebunny/crossref_metadata_2025 huggingface dataset:
Clues of the restarting active galactic nucleus activity of Mrk 1498 from GTC/MEGARA integral field spectroscopy data
Authors: Cazzoli S. , Hernández-García L. , Márquez I. , Masegosa J. , Bruni G. , Panessa F. , Bassani L.
Published: September 2024

Context. Some giant radio galaxies selected at X-rays with active galactic nuclei (AGN) show signs of a restarted nuclear activity (old lobes plus a nuclear young radio source probed by giga-hertz peaked spectra). The study of these sources gives us insights into the AGN activity history. More specifically, the kinematics and properties of the outflows can be used as a tool to describe the activity of the source.

Aims. One object in this peculiar class is Mrk 1498, a giant low-frequency double radio source that shows extended emission in [O III]. This emission is likely related to the history of the nuclear activity of the galaxy. We investigate whether this bubble-like emission might trace an outflow from either present or past AGN activity.

Methods. Using a medium-resolution spectroscopy (R ∼ 10 000) available with MEGARA/GTC, we derived kinematics and fluxes of the ionised gas from modelling the [O III] and Hβ features. We identified three kinematic components and mapped their kinematics and flux.

Results. All the components show an overall blue to red velocity pattern, with similar peak-to-peak velocities but a different velocity dispersion. At a galactocentric distance of ∼2.3 kpc, we found a blob with a velocity up to 100 km s−1, and a high velocity dispersion (∼170 km s−1) that is spatially coincident with the direction of the radio jet. The observed [O III]/Hβ line ratio indicates possible ionisation from AGN or shocks nearly everywhere. The clumpy structure visibile in HST images at kiloparsec scales show the lowest values of log[O III]/Hβ (< 1), which is likely not related to the photoionisation by the AGN.

Conclusions. Taking optical and radio activity into account, we propose a scenario of two different ionised gas features over the radio AGN lifecycle of Mrk 1498. The radio emission suggests at least two main radio activity episodes: an old episode at megaparsec scales (formed during a time span of ∼100 Myr), and a new episode from the core (> 2000 yr ago). At optical wavelengths, we observe clumps and a blob that are likely associated with fossil outflow. The latter is likely powered by past episodes of the flickering AGN activity that may have occurred between the two main radio phases.
The quantum yield of O(1S) in CO2 photolysis retrieved from the Martian atmosphere
Authors: Gkouvelis Leonardos , Akın Can , Heng Kevin
Published: September 2024

Photochemistry studies the interactions between light and molecules. Ultraviolet radiation interacts with the atmosphere, and due to its energy, it can dissociate, excite, or ionize its constituents, which initiate other processes. A good knowledge of the interaction between photons of different energies with molecules and atoms is crucial for accurately modeling the atmospheric physics and for climate predictions. Despite its importance, photo-fragment dynamics lacks data because the experimental setup is difficult. We used the upper Martian atmosphere as a natural laboratory to measure the quantum yield O(1S) from CO2 + hv as a function of wavelength. We analyzed 4 years of continuous remote-sensing observations from the NASA MAVEN/IUVS spectrograph within a Bayesian framework analysis tool. We retrieved the quantum yield for the first time through its entire production spectral range, ≈80–126 nm, and achieved uncertainty from 10% to 20% on average. While at Lyman-α (121.6 nm), we achieved a precision of 2% by taking advantage of the properties of the upper Martian atmosphere.
Impact of stellar population synthesis choices on forward modelling-based redshift distribution estimates
Authors: Tortorelli Luca , McCullough Jamie , Gruen Daniel
Published: September 2024

Context. The forward modelling of galaxy surveys has recently gathered interest as one of the primary methods to achieve the required precision on the estimate of the redshift distributions for stage IV surveys, allowing them to perform cosmological tests with unprecedented accuracy. One of the key aspects of forward modelling a galaxy survey is the connection between the physical properties drawn from a galaxy population model and the intrinsic galaxy spectral energy distributions (SEDs), achieved through stellar population synthesis (SPS) codes (e.g. FSPS). However, SPS requires a large number of detailed assumptions on the constituents of galaxies, for which the model choice or parameter values are currently uncertain.

Aims. In this work, we perform a sensitivity study of the impact that the variations of the SED modelling choices have on the mean and scatter of the tomographic galaxy redshift distributions.

Methods. We assumed the PROSPECTOR-β model as the fiducial input galaxy population model and used its SPS parameters to build 9-bands ugriZYJHKs observed-frame magnitudes of a fiducial sample of galaxies. We then built samples of galaxy magnitudes by varying one SED modelling choice at a time. We modelled the colour-redshift relation of these galaxy samples using the self-organising map (SOM) approach that optimally groups similar redshifts galaxies by their multidimensional colours. We placed galaxies in the SOM cells according to their simulated observed-frame colours and used their cell assignment to build colour-selected tomographic bins. Finally, we compared each variant’s binned redshift distributions against the estimates obtained for the original PROSPECTOR-β model.

Results. We find that the SED components related to the initial mass function, as well as the active galactic nuclei, the gas physics, and the attenuation law substantially bias the mean and the scatter of the tomographic redshift distributions with respect to those estimated with the fiducial model.

Conclusions. For the uncertainty of these choices currently present in the literature and regardless of the applied stellar mass function based re-weighting strategy, the bias in the mean and the scatter of the tomographic redshift distributions are greater than the precision requirements set by next-generation Stage IV galaxy surveys, such as the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) and Euclid.
The SRG/eROSITA all-sky survey
Authors: Zhang X. , Bulbul E. , Malavasi N. , Ghirardini V. , Comparat J. , Kluge M. , Liu A. , Merloni A. , Zhang Y. , Bahar Y. E. , Artis E. , Sanders J. S. , Garrel C. , Balzer F. , Brüggen M. , Freyberg M. , Gatuzz E. , Grandis S. , Krippendorf S. , Nandra K. , Ponti G. , Ramos-Ceja M. , Predehl P. , Reiprich T. H. , Veronica A. , Yeung M. C. H. , Zelmer S.
Published: September 2024

The properties of the warm-hot intergalactic medium (WHIM) in cosmic filaments are among the least quantified units in modern astrophysics. The Spectrum Roentgen Gamma/eROSITA All Sky Survey (SRG/eRASS) provides a unique opportunity to study the X-ray emission of the WHIM. We applied both imaging and spectroscopic stacking techniques to the data of the first four eRASS scans to inspect the X-ray emissions from 7817 cosmic filaments identified from Sloan Digital Sky Survey (SDSS) optical galaxy samples. We obtained a 9σ significant detection of the total X-ray signal from filaments in the 0.3–1.2 keV band. Here, we introduce a novel method to estimate the contamination fraction from unmasked X-ray halos, active galactic nuclei, and X-ray binaries associated with filament galaxies. We found an approximately 40% contamination fraction for these unmasked sources, suggesting that the remaining 60% of the signal could be coming from the WHIM and a 5.4σ detection significance of the WHIM. Moreover, we modeled the temperature and baryon density contrast of the detected WHIM by fitting the stacked spectrum and surface brightness profile. The best-fit temperature log(T/K) = 6.84 ± 0.07, obtained by using a single temperature model, is marginally higher than in the simulation results. This could be due to the fitting of a single temperature model on a multi-temperature spectrum. Assuming a 0.2 solar abundance, the best-fit baryon density contrast logΔb = 1.88 ± 0.18 is in general agreement with the X-ray emitting phases in the IllustrisTNG simulation. This result suggests that the broadband X-ray emission traces the high end of the temperature and density values that characterize the entire WHIM population.
Anomalously low-mass core-He-burning star in NGC 6819 as a post-common-envelope phase product
Authors: Matteuzzi Massimiliano , Hendriks David , Izzard Robert G. , Miglio Andrea , Brogaard Karsten , Montalbán Josefina , Tailo Marco , Mazzi Alessandro
Published: September 2024

Precise masses of red giant stars enable a robust inference of their ages, but there are cases where these age estimates are very precise but also very inaccurate. Examples are core-helium-burning (CHeB) stars that have lost more mass than predicted by standard single-star evolutionary models. Members of star clusters in the Kepler database represent a unique opportunity to identify such stars because they combine exquisite asteroseismic constraints with independent age information (members of a star cluster share a similar age and chemical composition). We focus on the single metal-rich (Z ≈ Z⊙) Li-rich low-mass CHeB star KIC4937011, which is a member of the open cluster NGC 6819 (turn-off mass of ≈1.6 M⊙, i.e. an age of ≈2.4 Gyr). This star has a lower mass by ≈1 M⊙ than expected for its age and metallicity, which might be explained by binary interactions or mass loss along the red giant branch (RGB). To infer formation scenarios for this object, we performed a Bayesian analysis by combining the binary stellar evolutionary framework BINARY_C V2.2.3 with the dynamic nested-sampling approach contained in the DYNESTY V2.1.1 package. We find that this star probably is the result of a common-envelope evolution (CEE) phase during the RGB stage of the primary star in which the low-mass (< 0.71 M⊙) main-sequence companion does not survive. The mass of the primary star at the zero-age main sequence is in the range [1.46, 1.71] M⊙, with a log-orbital period in the range [0.06, 2.4] log10(days). During the CEE phase, ≈1 M⊙ of material is ejected from the system, and the final star reaches the CHeB stage after helium flashes as if it were a single star with a mass of ≈0.7 M⊙, which is what we observe today. Although the proposed scenario is consistent with photometric and spectroscopic observations, a quantitative comparison with detailed stellar evolution calculations is needed to quantify the systematic skewness of the radius, luminosity, and effective temperature distributions towards higher values than observations.
Multi-kilogauss magnetic field driving the magnetospheric accretion process in EX Lupi
Authors: Pouilly K. , Audard M. , Kóspál Á. , Lavail A.
Published: September 2024

Context. EX Lupi is the prototype of EX Lup-type stars, which are classical T Tauri stars (cTTSs) with luminosity bursts and outbursts of 1–5 magnitudes that last for a few months to a few years. These events are ascribed to an episodic accretion that can occur repeatedly, but whose physical mechanism is still debated.

Aims. We aim to investigate the magnetically driven accretion of EX Lup in quiescence. We include for the first time a study of the small- and large-scale magnetic field. This allows us to characterise the magnetospheric accretion process of the system completely.

Methods. We used spectropolarimetric times series acquired in 2016 and 2019 with the Echelle SpectroPolarimetric Device for the Observation of Stars and in 2019 with the SpectroPolarimètre InfraRouge at the Canada-France-Hawaii telescope during a quiescence phase of EX Lup. We were thus able to perform a variability analysis of the radial velocity, the emission lines, and the surface-averaged longitudinal magnetic field in different epochs and wavelength domains. We also provide a small-scale magnetic field analysis using Zeeman intensification of photospheric lines and a large-scale magnetic topology reconstruction using Zeeman-Doppler imaging.

Results. Our study reveals that typical magnetospheric accretion is ongoing on EX Lup. A main accretion funnel flow connects the inner disc to the star in a stable fashion and produces an accretion shock on the stellar surface close to the pole of the magnetic dipole component. We also measure one of the strongest fields ever observed on cTTSs. This strong field indicates that the disc is truncated by the magnetic field close to but beyond the corotation radius, where the angular velocity of the disc equals the angular velocity of the star. This configuration is suitable for a magnetically induced disc instability that yields episodic accretion onto the star.
Suggested magnetic braking prescription derived from field complexity fails to reproduce the cataclysmic variable orbital period gap
Authors: Ortúzar-Garzón Valentina , Schreiber Matthias R. , Belloni Diogo
Published: September 2024

Context. Magnetic wind braking drives the spin-down of low-mass stars and the evolution of most interacting binary stars. A magnetic braking prescription that was claimed to reproduce both the period distribution of cataclysmic variables (CVs) and the evolution of the rotation rates of low-mass stars is based on a relation between the angular momentum loss rate and magnetic field complexity.

Aims. The magnetic braking model based on field complexity has been claimed to predict a detached phase that could explain the observed period gap in the period distribution of CVs but has never been tested in detailed models of CV evolution. Here we fill this gap.

Methods. We incorporated the suggested magnetic braking law in MESA and simulated the evolution of CVs for different initial stellar masses and initial orbital periods.

Results. We find that the prescription for magnetic braking based on field complexity fails to reproduce observations of CVs. The predicted secondary star radii are smaller than measured, and an extended detached phase that is required to explain the observed period gap (a dearth of non-magnetic CVs with periods between ∼2 and ∼3 hours) is not predicted.

Conclusions. Proposed magnetic braking prescriptions based on a relation between the angular momentum loss rate and field complexity are too weak to reproduce the bloating of donor stars in CVs derived from observations and, in contrast to previous claims, do not provide an explanation for the observed period gap. The suggested steep decrease in the angular momentum loss rate does not lead to detachment. Stronger magnetic braking prescriptions and a discontinuity at the fully convective boundary are needed to explain the evolution of close binary stars that contain compact objects. The tension between braking laws derived from the spin-down of single stars and those required to explain CVs and other close binaries containing compact objects remains.
Penser l’amélioration des conditions de vie dans des quartiers défavorisés : apports d’une approche ancrée dans l’expérience vécue des habitants
Authors: Legendre Anne-Laure , Combes Benjamin , Remvikos Yorghos
Published: September 2024

La politique de la ville et les projets de renouvellement urbain tentent de restaurer cohésion urbaine et sociale au sein des territoires, et d’améliorer les conditions de vie des habitants des quartiers dits prioritaires depuis plusieurs dizaines d’années. Les bilans de ces interventions montrent des résultats mitigés, et de nombreuses voix suggèrent un changement radical d’approche pour mieux considérer les habitants et le potentiel de ces quartiers. Notre démarche propose de partir de l’expérience de vie des habitants pour comprendre leur rapport au cadre de vie, en prenant appui sur les résultats d’enquêtes, inspirées d’approches ethnographiques. Nous présentons les dissymétries repérées entre les postures naturalistes caractérisant l’expertise et les politiques urbaines sur ces territoires, et une posture humaniste, centrée sur le vécu des habitants, montrant que l’expérience d’habiter un lieu s’exprime à travers d’autres mots et d’autres heuristiques. Nous discutons des apports de ce changement d’ordre épistémologique pour dépasser certaines limitations des catégories analytiques préétablies et révéler des impensés dans la manière d’évaluer la qualité du cadre de vie et de penser son amélioration.
Iridium-Catalyzed Leuckart-Type Reductive Amination of Carbonyls
Authors: Liao Jianhua , Luo Renshi , Liu Liang , Tong Jinghui , Ouyang Lu
Published: September 2024

Formamides are fundamental motifs that are prevalent in drugs, pesticides, dyes, and fragrances. Herein, we described an iridium-catalyzed Leuckart-type reductive amination of carbonyls, delivering formamides in moderate to excellent yields. In this process, ammonium formate was used as the N-formylating reagent to produce the formamide products. This protocol provides a new procedure for formamide synthesis.
The Development of Radical/Palladium Relay Catalysis for C–H Carbonylation
Authors: Huang Hanmin , Ding Yongzheng
Published: September 2024

The radical/palladium relay catalysis for C–H bond carbonylation is an attractive research topic in synthetic chemistry. It can rapidly prepare carbonylated molecules for synthetic or pharmaceutical applications from highly sought-after feedstocks, such as alkylarenes, alkanes, alkenes, or ethers. The main objective of this Synpacts article is to summarize the development of this research area, mainly focusing on radical/palladium relay catalysis for the carbonylation of single and double C–H bonds.

1 Introduction

2 Radical/Palladium Relay Catalysis for Single C–H Bond Carbonylation Reaction

3 Radical/Palladium Relay Catalysis for Double C–H Bond Carbonylation Reaction

4 Conclusions
Charcot's Russian pupils
Authors: Teive Hélio Afonso Ghizoni , Coutinho Léo , Camargo Carlos Henrique Ferreira
Published: September 2024

The establishment of Russian neurology in the late 19th century was significantly shaped by the neurology department at La Salpêtrière Hospital under Professor Jean-Martin Charcot's leadership. A group of Russian neurologists, guided by Professor Kozhevnikov and featuring his disciples such as Korsakov, Minor, Darkshevich, and Bekhterev, had the privilege of being mentored by Professor Charcot. Subsequently, they played pivotal roles in founding various neurology services in Russia, greatly influenced by the teachings and insights they acquired under Charcot's tutelage.
Solutions for a flame propagation model in porous media based on Hamiltonian and regular perturbation methods
Authors: Rahman Saeed ur , Díaz Palencia José Luis
Published: September 2024

This article extends the exploration of solutions to the issue of flame propagation driven by pressure and temperature in porous media that we introduced in earlier papers. We continue to consider a p-Laplacian type operator as a mathematical formalism to model slow and fast diffusion effects, that can be given in the non-homogeneous propagation of flames. In addition, we introduce a forced convection to model any possible induced flow in the porous media. We depart from previously known models to further substantiate our driving equations. From a mathematical standpoint, our goal is to deepen in the understanding of the general behavior of solutions via analyzing their regularity, boundedness, and uniqueness. We explore stationary solutions through a Hamiltonian approach and employ a regular perturbation method. Subsequently, nonstationary solutions are derived using a singular exponential scaling and, once more, a regular perturbation approach.
Modeling of nonequilibrium effects in a compressible plasma based on the lattice Boltzmann method
Authors: Huang Haoyu , Jin Ke , Li Kai , Zheng Xiaojing
Published: September 2024

A magnetohydrodynamic lattice Boltzmann method (MHD-LBM) model for a 2D compressible plasma based on the finite volume scheme is established. The double distribution D2Q17 discrete velocities are used to simulate the fluid field. The hyperbolic Maxwell equations, which satisfy the elliptic constraints of Maxwell's equations and the constraint of charge conservation, are used to simulate the electromagnetic field. The flow field and electromagnetic field are coupled to simulate a compressible plasma through the electromagnetic force and magnetic induction equations. Four typical cases, the Taylor vortex flow, strong blast, Orszag–Tang vortex, and one-dimensional Riemann problems, are simulated to validate the MHD-LBM model for a compressible plasma. It is found that shock waves widely exist in a compressible plasma, and strong nonequilibrium effects exist around each shock wave. The quantitative simulation for the Brio–Wu problem demonstrates that this model can easily obtain the physical characteristics of nonequilibrium effects at sharp interfaces (shock waves and detonation waves). The magnetic fields can affect the magnitudes to which the system deviates from its equilibrium state. The viscosity can increase the magnitudes to which the system deviates from its equilibrium state. Compared with existing compressible MHD, these results for nonequilibrium effects can provide mesoscopic physical insights into the flow mechanism of a shock wave in a supersonic plasma.
Monolayer-scale AlN/GaN digital alloys grown by plasma-assisted molecular beam epitaxy
Authors: Li Siqi , Liang Xiao , Shao Pengfei , Chen Songlin , Li Zhenhua , Su Xujun , Tao Tao , Xie Zili , Khan M. Ajmal , Wang Li , Lin T. T. , Hirayama Hideki , Liu Bin , Chen Dunjun , Wang Ke , Zhang Rong
Published: September 2024

The efficiency of usual AlGaN based deep ultraviolet light-emitting devices is still quite low. The difficulties are basically originated from the fundamental material properties of AlGaN. This work has adopted monolayer-scale (AlN)m/(GaN)n ordered digital alloys (DAs) as alternatives to AlGaN random alloys, m and n are the numbers of monolayers. X-ray diffraction scans have demonstrated clear satellite peaks, verifying good periodicity of AlN/GaN DAs grown by molecular beam epitaxy (MBE), and transmission electron microscopy results have revealed atomically sharp and smooth interfaces and quite precise m:n values agreeing well with designs. The electron densities of Si-doped (AlN)m/(GaN)n DAs with high equivalent Al compositions are significantly higher than those of conventional AlGaN:Si random alloys grown in the same MBE system. Si dopant ionization energies in DAs are only 2–5 meV, much lower than that for usual random alloys. The red shift of the light emission for DAs with thinner AlN barriers has suggested strong coupling between the GaN wells and thus formation of a miniband in a vertical direction. The results have demonstrated the potential of the (AlN)m/(GaN)n DAs as electronically functional alternatives for various device applications.
Frontier system-on-chip (SoC) technology for microwave diagnostics (invited)
Authors: Chen Ying , Chen Pin-Jung , Hu Robert , Zhu Yilun , Yu Jo-Han , Pham A.-V. , Momeni Omeed , Domier Calvin , Dannenberg Jon , Li Xiaoliang , Yu Guanying , Luhmann Neville
Published: September 2024

The next generation of fusion reactors, exemplified by projects such as the Demonstration Power Plant following the International Thermonuclear Experimental Reactor, faces the monumental challenge of proving the viability of generating electricity through thermonuclear fusion. This pursuit introduces heightened complexities in diagnostic methodologies, particularly in microwave-based diagnostics. The increased neutron fluence necessitates significant reductions in vessel penetrations and the elimination of internal diagnostics, posing substantial challenges. SoC technology offers a promising solution by enabling the miniaturization, modularization, integration, and enhancing the reliability of microwave systems. After seven years of research, our team successfully pioneered the V- and W-band system-on-chip approach, leading to the development of active transmitters and passive receiver modules applied in practical settings, notably within the DIII-D tokamak project. Arrays of these modules have supported microwave imaging diagnostics. New physics measurement results from the Electron Cyclotron Emission Imaging system on DIII-D provide compelling evidence of improved diagnostics following the adoption of SoC technology. Furthermore, we achieved a breakthrough in developing an F-band SoC, advancing higher frequency capabilities for fusion devices. These achievements represent a significant leap forward in fusion diagnostic technology, marking substantial progress toward establishing reliable and efficient plasma diagnostics for future fusion reactors.
Impact of orbital hybridization on spin-polarized electronic transport through Ni-MAPbI3 interfaces
Authors: Zhang Xiangpeng , Li Wei , Li Yang , Jiang Linze , Zhu Xixiang , Yu Haomiao , Li Jinpeng , Shi Yumeng , Yi Ding , Wang Kai
Published: September 2024

The solution-processed methylammonium lead tri-iodine (MAPbI3), with long spin lifetimes and large spin diffusion lengths, has merit for developing stable perovskite spin valves (PeSV) with low saturation fields. By far, it remains challenging to avoid ill-defined ferromagnet-MAPbI3 interfaces during device fabrications using solution methods and to quantify the hybridized interfacial electronic and magnetic structures. Herein, an annealing-free method was developed for the fabrication of MAPbI3 based PeSV. In comparison to a thermally annealed device, an improved room temperature magnetoresistance (MR) was achieved. We found remarkable interfacial contributions to anisotropic magnetoresistance and MR. The first-principles calculation was further adopted to quantify the interfacial spin and orbital moments. Our results suggest that the orbital hybridization and the spin transfer are remarkable for the formation of the spin-dependent interfacial density of states. It consequently affects magnetic switching behaviors. This study holds an exceptionally important role for a deep understanding of the spin-polarized electronic transport through the Ni-MAPbI3 hybridized interface.
Wing ice accretion prediction based on conditional generation adversarial network
Authors: Ma Xudong , Zhang Yang , Xu Xiaogang , Wang Hui , Wang Tianbo
Published: September 2024

The ice accretion on the aircraft's surface under low temperatures and high humidity is crucial for flight safety. With respect to the limitation of traditional icing simulation methods, it is very hard to predict exact ice profiles, which can extremely affect the flight performance of an aircraft. A conditional generative adversarial network (CGAN) is utilized to rapidly predict ice accretion and reconstruct three-dimensional ice patterns along the leading edge of a wing. The CGAN is trained using experimental data obtained from a wing with varying sweep angles. The results indicate that the CGAN achieves a high level of accuracy, specifically 97.5%, in predicting the similarity of ice shapes in the test set. When assessing the sample feature capture and prediction capability of the predictive model, it is shown that the CGAN exhibits superior predictive performance across different sample sizes.
Development of backward compatible physics-informed neural networks to reduce error accumulation based on a nested framework
Authors: Gao Lei , Chen Yaoran , Hu Guohui , Zhang Dan , Zhang Xiangyu , Li Xiaowei
Published: September 2024

Physical information neural network (PINN) provides an effective method for solving partial differential equations, and many variants have been derived, the most representative of which is backward compatible physical information neural network (BC-PINN). The core of BC-PINN is to use the prediction of the previous time period as the label data of the current time period, which leads to error accumulation in the process of backward compatibility. To solve this problem, a nested backward compatible physical information neural network (NBC-PINN) is proposed in this paper. NBC-PINN has an overlap region between the computation domain of the previous time period and the computation domain of the current time period, which is trained twice in total. Numerical experiments on four representative time-varying partial differential equations show that NBC-PINN can effectively reduce error accumulation, improve computational efficiency and accuracy, and improve the L2 relative error of the numerical solution with fewer residual allocation points. The development of NBC-PINN provides a theoretical basis for the scientific calculation of partial differential equations, and promotes the progress of PINN to a certain extent.
Jet mixing optimization using a flexible nozzle, distributed actuators, and machine learning
Authors: Jiang Zhutao , Cornejo Maceda Guy Y. , Li Yiqing , Shaqarin Tamir , Gao Nan , Noack Bernd R.
Published: September 2024

In this paper, we introduce the first jet nozzle allowing simultaneous shape variation and distributed active control, termed “Smart Nozzle” in the sequel. Our Smart Nozzle manipulates the jet with an adjustable flexible shape via 12 equidistant stepper motors and 12 equidistantly placed inward-pointing minijets. The mixing performance is evaluated with a 7 × 7 array of Pitot tubes at the end of the potential core. The experimental investigation is carried out in three steps. First, we perform an aerodynamic characterization of the unforced round jet flow. Second, we investigate the mixing performance under five representative nozzle geometries, including round, elliptical, triangular, squared, and hexagonal shapes. The greatest mixing area is achieved with the square shape. Third, the symmetric forcing parameters are optimized for each specified nozzle shape with a machine learning algorithm. The best mixing enhancement for a symmetric active control is obtained by the squared shape, which results in a 1.93-fold mixing area increase as compared to the unforced case. Symmetrically unconstrained forcing achieves a nearly 4.5-fold mixing area increase. The Smart Nozzle demonstrates the feasibility of novel flow control techniques that combine shape variation and active control, leveraging the capabilities of machine learning optimization algorithms.
The topology-conditioned turbulence kinetic energy budget
Authors: Baj Pawel
Published: September 2024

The paper reports on the conditionally averaged turbulence kinetic energy (TKE) budget, where the conditioning is based on the invariants of the velocity gradient tensor. Three different datasets are utilized for this analysis. The particular terms of the budget are presented in the (R, Q) plane, showcasing a striking similarity (both quantitative and qualitative) among the results from each dataset. The importance of conditional averages for the overall variance of the specific terms of the TKE budget is also evaluated. Subsequently, the budgets are presented along conditional mean trajectories (CMTs), revealing the dynamics of the TKE budget associated with the evolution of local flow topology. Results obtained for different CMTs approximately collapse when suitably normalized (at least for certain parts of the trajectories). The conditional budget is clearly dominated by inertial and pressure transport terms, indicative of a “sweeping” effect.
Cement slurry penetration behavior of swirl grouting technology
Authors: Liang Weiqun , Chen Xiaobin , Tang Lubo , Zhang Jiasheng , Zhang Xinxin , Lin Fantong , Cheng Jun
Published: September 2024

Traditional pressure grouting technology operates under steady pressure conditions, causing the grout to easily flow along preferential pathways. This results in uneven grout penetration and increased economic costs. This study proposes swirl grouting technology, which effectively improves this problem. To verify the effectiveness of swirl grouting, a fan-shaped blade tool was also proposed. The grout penetration performance was investigated through experimental studies. The length, width, height, weight, and uniformity of the grouted bodies produced by the swirl grouting method were compared with those produced by the steady pressure grouting method. Then, the mechanisms of swirl grouting were analyzed through transparent disc visualization experiments. The results demonstrated that, at different water–cement ratios, the swirl device increased the penetration length in the X, Y, and Z directions by 43.3%, 27.8%, and 45.8%, respectively, compared to the conventional straight device, and by 57.3%, 39.4%, and 55.6%, respectively, compared to the fan blade device. Moreover, the swirl device increased the weight of the grouted stone body by 54.9% compared to the conventional straight device and by 91.0% compared to the fan blade device, significantly enhancing filling efficiency. The uniformity coefficient of the swirl device permeation decreased by 56.6% and 51.0%, respectively, compared to the conventional straight device and the fan blade device, resulting in a more uniform grout distribution. The transparent disc visualization experiment further revealed the advantage of the swirl device in promoting the migration of fine particles, with a significant increase in average penetration distance and a penetration shape closer to a regular circle. The rotating flow path of the swirl device imparts additional rotational momentum and multidirectional penetration capabilities. The resulting turbulence accelerates the mixing of grout with the soil matrix, facilitating the migration of fine particles, expanding flow channels, and reducing flow resistance. This combination of effects enhances penetration efficiency and reduces energy loss. This study offers significant practical application value for improving engineering quality, construction efficiency, and reducing costs.
Passive control of porous media on the aerodynamic forces and wake structures of wall-mounted short circular cylinders
Authors: Feng Huanhuan , Liu Weijian , Dong Yuhong
Published: September 2024

This paper numerically investigates the aerodynamic forces and the three-dimensional wake characteristics of wall-mounted circular cylinders with and without porous media coatings using large eddy simulation at a Reynolds number of 3.2×104. Short cylinders with aspect ratios of 0.5, 1.0, and 3.0 are considered, with one end fixed to a bottom wall in the current work. The study focuses on aerodynamic coefficients, flow characteristics, and wake structures for cylinders both with and without porous coatings. The statistical results indicate that porous media significantly alter flow patterns behind the cylinders, suppress downwash flow from the free end, and reduce velocity fluctuations and turbulent kinetic energy within the wake. The porous coating enhances the leeward side's base pressure, leading to a reduction in drag on the cylinder surface. The analysis of flow structures reveals that the topology of the arch vortex behind solid cylinders is significantly dependent on the aspect ratio, whereas this dependency is negligible for porous cylinders. Porous coatings diminish the intensity of the tip and trailing vortices behind the cylinder. Finally, based on the time-averaged flow field, we proposed two conceptual models of topological correlation for wall-mounted short cylinders, both with and without porous coatings, which contributes to describing the geometric characteristics and interactions of vortex structures.
High-performing organic/quantum dot hybrid upconversion device based on a single-component near-infrared-sensitive layer
Authors: Wang Ke , Hu Yuanhong , Chen Lixiang , Jiang Haijun , Jiang Haohong , Tan Xingwen , Zhang Qiaoming , Lei Yanlian
Published: September 2024

A donor/acceptor (D/A) heterojunction with an interfacial energetic offset is demonstrated to enable efficient exciton dissociation in organic photodetectors and upconversion devices (UCDs). Unfortunately, this approach usually encounters complicated optimization procedures and interfacial instability. Herein, we present an alternative strategy for achieving high-performing UCDs by utilizing an organic single-component near-infrared (NIR)-sensitive layer instead of a D/A heterojunction. The showcased UCD is constructed by vertically stacking an organic single-component Y6 NIR-detection unit and a quantum dot light-emitting unit. Due to the high dielectric constant and low exciton binding energy of the non-fullerene acceptor Y6, free carriers are directly and spontaneously generated upon NIR light excitation. As a result, the single-component UCD achieves a low light detection capability of 2.5 μW/cm2, a fast refresh rate of >3.8 × 104, and a high resolution exceeding 1100 dpi, providing a stable optical response to high-frequency NIR signals and high-quality NIR imaging.
Numerical analysis of hydrophobic surface effects on cavitation inception and evolution in high-speed centrifugal pumps for thermal energy storage and transfer systems
Authors: Guo Dajiang , Wang Cong , Ruan Yu , Yin Hongmei , Fan XiaoXu , Wang Ziwei , Jiang MingDa , Zhang Lei
Published: September 2024

This study explores the influence of wettability surfaces on cavitation inception and evolution in high-speed centrifugal pumps used for thermal energy storage and transfer systems through numerical simulations. The simulations were conducted using the Kunz mass transfer model implemented in Fluent, combined with the Eulerian multiphase flow approach and the shear stress transport k–ω turbulence model. The cavitation dynamics were analyzed across contact angles ranging from superhydrophilic to superhydrophobic conditions. The results demonstrate that superhydrophobic surfaces delay cavitation onset compared to hydrophilic ones, reducing the critical cavitation coefficient by at least 28%. At flow rates of 1.11 Q0 and 0.89 Q0, cavitation numbers show distinct trends, with superhydrophobic surfaces enhancing cavitation stability and reducing the frequency of cavitation shedding. The reentrant jet dynamics are also affected, with increased hydrophobicity weakening the jets and stabilizing cavitation zones. This research aims to advance the understanding of using surface wettability to manage cavitation in high-speed centrifugal pumps, thereby improving the performance and reliability of thermal energy storage and transfer systems.
MINFLUX reveals dynein stepping in live neurons
Authors: Schleske Jonas M. , Hubrich Jasmine , Wirth Jan Otto , D’Este Elisa , Engelhardt Johann , Hell Stefan W.
Published: September 2024

Dynein is the primary molecular motor responsible for retrograde intracellular transport of a variety of cargoes, performing successive nanometer-sized steps within milliseconds. Due to the limited spatiotemporal precision of established methods for molecular tracking, current knowledge of dynein stepping is essentially limited to slowed-down measurements in vitro. Here, we use MINFLUX fluorophore localization to directly track CRISPR/Cas9-tagged endogenous dynein with nanometer/millisecond precision in living primary neurons. We show that endogenous dynein primarily takes 8 nm steps, including frequent sideways steps but few backward steps. Strikingly, the majority of direction reversals between retrograde and anterograde movement occurred on the time scale of single steps (16 ms), suggesting a rapid regulatory reversal mechanism. Tug-of-war-like behavior during pauses or reversals was unexpectedly rare. By analyzing the dwell time between steps, we concluded that a single rate-limiting process underlies the dynein stepping mechanism, likely arising from just one adenosine 5′-triphosphate hydrolysis event being required during each step. Our study underscores the power of MINFLUX localization to elucidate the spatiotemporal changes underlying protein function in living cells.
Welfare concerns of farm-based therapy and education: People and Animals UK CIC
Authors: Bristow Katie , Milsom Julie
Published: September 2024

Can humans engage with farm animals in a way that maintains, perhaps enhances, the welfare of farm animals? Can communities learn to engage with farm animals in a manner similar to that of companion animals? Is it even fair to ask about farm animals? We hope to offer a contribution to this discussion, using a case study from People and Animals UK CIC to explore the impact of farm animals on people and their communities, but with a focus on how farm design and session delivery might impact the animal within the dynamic.
Cryogenic Digital Image Correlation as a Probe of Strain in Iron-Based Superconductors
Authors: Mo 莫 Ziye 子夜 , Li 李 Chunyi 春熠 , Zhang 张 Wenting 文婷 , Liu 刘 Chang 畅 , Sun 孙 Yongxin 永欣 , Liu 刘 Ruixian 瑞鲜 , Lu 鲁 Xingye 兴业
Published: September 2024

Uniaxial strain is a powerful tuning parameter that can control symmetry and anisotropic electronic properties in iron-based superconductors. However, accurately characterizing anisotropic strain can be challenging and complex. Here, we utilize a cryogenic optical system equipped with a high-spatial-resolution microscope to characterize surface strains in iron-based superconductors using the digital image correlation method. Compared with other methods such as high-resolution x-ray diffraction, strain gauge, and capacitive sensor, digital image correlation offers a non-contact full-field measurement approach, acting as an optical virtual strain gauge that provides high spatial resolution. The results measured on detwinned BaFe2As2 are quantitatively consistent with the distortion measured by x-ray diffraction and neutron Larmor diffraction. These findings highlight the potential of cryogenic digital image correlation as an effective and accessible tool for probing the isotropic and anisotropic strains, facilitating applications of uniaxial strain tuning in research of quantum materials.
Centimeter-Scale Above-Room-Temperature Ferromagnetic Fe3GaTe2 Thin Films by Molecular Beam Epitaxy
Authors: Wang 王 Taikun 太坤 , Xu 徐 Yongkang 永康 , Liu 刘 Yu 宇 , Dai 代 Xingze 兴泽 , Yan 闫 Pengfei 鹏飞 , Wang 王 Jin 瑾 , Wang 王 Shuanghai 双海 , Deng 邓 Yafeng 亚丰 , He 何 Kun 坤 , Li 李 Caitao 彩涛 , Wang 王 Ziang 子昂 , Zou 邹 Wenqin 文琴 , Wen 温 Rongji 荣吉 , Hao 郝 Yufeng 玉峰 , He 何 Liang 亮
Published: September 2024

Fe3GaTe2, as a layered ferromagnetic material, has a Curie temperature (T
c) higher than room temperature, making it the key material in next-generation spintronic devices. To be used in practical devices, large-sized high-quality Fe3GaTe2 thin films need to be prepared. Here, the centimeter-scale thin film samples with high crystal quality and above-room-temperature ferromagnetism with strong perpendicular magnetic anisotropy were prepared by molecular beam epitaxy technology. Furthermore, the T
c of the samples raises as the film thickness increases, and reaches 367 K when the film thickness is 60 nm. This study provides material foundations for the new generation of van der Waals spintronic devices and paves the way for the commercial application of Fe3GaTe2.
Strong field-induced quantum dynamics in atoms and small molecules
Authors: Eckart S
Published: September 2024

High-intensity laser fields can ionize atoms and molecules and also initiate molecular dissociation. This review is on the recent progress made using experiments that harness the potential of cold-target recoil-ion momentum spectroscopy and femtosecond laser pulses with tailored intense fields. The possibility to image the molecular structure and the orientation of small molecules via the detection of the momenta of the ions is illustrated. The process of non-adiabatic tunnel ionization is analyzed in detail focusing on the properties of the electronic wave packet at the tunnel exit. It is reviewed how the electron gains angular momentum and energy during tunneling in circularly polarized light. The electron is a quantum object with an amplitude and a phase. Most experiments in strong field ionization focus on the absolute square of the electronic wave function. The technique of holographic angular streaking of electrons enables the retrieval of Wigner time delays in strong field ionization, which is a property of the electronic wave function’s phase in momentum space. The relationship between the phase in momentum space and the amplitudes in position space enables access to information about the electron’s position at the tunnel exit. Finally, recent experiments studying entanglement in strong field ionization are discussed.
MRNet: rolling bearing fault diagnosis in noisy environment based on multi-scale residual convolutional network
Authors: Deng Linfeng , Zhao Cheng , Wang Xiaoqiang , Wang Guojun , Qiu Ruiyu
Published: September 2024

Vibration signal collection of rolling bearings in the complex working environment often suffers from significant noise interference, rendering traditional fault diagnosis methods ineffective. To address this challenge, we propose a multi-scale residual convolutional network (MRNet) for diagnosing rolling bearing faults in noisy environments. The MRNet model features multiple convolution branches, each of which utilizes kernels with different sizes to capture fault information at different scales, so this multi-scale framework excels at extracting both local and global information from raw fault vibration signals, enhancing fault recognition accuracy. Additionally, we introduce residual blocks to maintain global information during the convolution operations, preventing useful feature information loss. To further improve global feature extraction capability of the network model, a lightweight Transformer module is developed and incorporated, compensating for some global information that the network’s front-end might fail to capture. The effectiveness of MRNet is validated by using two publicly available rolling bearing fault datasets and our own experiment dataset. The verification results indicate that MRNet outperforms other comparative models, particularly for complex fault diagnosis in noisy environments.
High-efficiency surface defect detection based on laser ultrasonic state space embedding and compressive sensing
Authors: Du Kanjie , Lan Longhui , Ni Na , Xie Guangping
Published: September 2024

The laser nonlinear wave modulation spectroscopy(LNWMS) technique has gained considerable attention due to its high sensitivity in detecting small surface defects and its ultra-fast scanning speed. This paper proposes a novel method for synthesizing intact wavefield reference, significantly enhancing the accuracy of surface defect imaging. Moreover, considering the potential for parallel processing of the nonlinearity calculation of ultrasonic signals at scanning points, we incorporate compressive sensing technology to accelerate this process. This innovative approach reduces the computational load to 10% of the original, thereby substantially increasing the imaging speed. The paper validates the method’s superior accuracy and efficiency in defect detection through conducting experiments using a high-speed laser ultrasonic scanning system on aluminum plates and turbine blade, and by comparing with local wavenumber estimation, demonstrating the promising potential of this technology for surface defect analysis.
Quantum-assisted rendezvous on graphs: explicit algorithms and quantum computer simulations
Authors: Tucker J , Strange P , Mironowicz P , Quintanilla J
Published: September 2024

We study quantum advantage in one-step rendezvous games on simple graphs analytically, numerically, and using noisy intermediate-scale quantum (NISQ) processors. Our protocols realise the recently discovered (Mironowicz 2023 New J. Phys.
25 013023) optimal bounds for small cycle graphs and cubic graphs. In the case of cycle graphs, we generalise the protocols to arbitrary graph size. The NISQ processor experiments realise the expected quantum advantage with high accuracy for rendezvous on the complete graph K
3. In contrast, for the graph

2

K
4

, formed by two disconnected 4-vertex complete graphs, the performance of the NISQ hardware is sub-classical, consistent with the deeper circuit and known qubit decoherence and gate error rates.