bluuebunny/crossref_metadata_2025 huggingface dataset:
First study of the supernova remnant population in the Large Magellanic Cloud with eROSITA
Authors: Zangrandi Federico , Jurk Katharina , Sasaki Manami , Knies Jonathan , Filipović Miroslav D. , Haberl Frank , Kavanagh Patrick , Maitra Chandreyee , Maggi Pierre , Saeedi Sara , Bernreuther Dominic , Koribalski Bärbel S. , Points Sean , Staveley-Smith Lister
Published: November 2024

Aims. The all-sky survey carried out by the extended Roentgen Survey with an Imaging Telescope Array (eROSITA) on board Spektrum-Roentgen-Gamma (Spektr-RG, SRG) has provided spatially and spectrally resolved X-ray data of the entire Large Magellanic Cloud (LMC) and its immediate surroundings in the soft X-ray band down to 0.2 keV, with an average angular resolution of 26″ in the field of view. In this work, we study the supernova remnants (SNRs) and SNR candidates in the LMC using data from the first four all-sky surveys (eRASS:4). From the X-ray data, in combination with results at other wavelengths, we obtain information about the SNRs, their progenitors, and the surrounding interstellar medium (ISM). Studying the entire population of SNRs in a galaxy aids in understanding the underlying stellar populations, the environments in which the SNRs are evolving, and the stellar feedback on the ISM.

Methods. The eROSITA telescopes are the best instruments currently available for the study of extended soft sources such as SNRs in an entire galaxy due to their large field of view and high sensitivity in the softer part of the X-ray band. We applied the Gaussian gradient magnitude filter to the eROSITA images of the LMC in order to highlight the edges of the shocked gas and find new SNRs. We visually compared the X-ray images with those of their optical and radio counterparts to investigate the true nature of the extended emission. The X-ray emission was evaluated using the contours with respect to the background, while for the optical, we used line ratio diagnostics and non-thermal emission in the radio images. We used the Magellanic Cloud Emission Line Survey for the optical data. For the radio comparison, we used data from the Australian Square Kilometre Array Pathfinder survey of the LMC. Using the star formation history derived from the near-IR photometry of the VISTA survey of the Magellanic Clouds, we investigated the possible progenitor type of the new SNRs and SNR candidates in our sample.

Results. We present the most up-to-date catalogue of SNRs in the LMC. Previously known SNRs and SNR candidates were detected with a 1σ significance down to a surface brightness of Σ [0.2–5.0 keV] = 3.0 × 10−15 erg s−1 cm−2 arcmin−2 and were examined. The eROSITA data allowed us to confirm one of the previous candidates as an SNR. We confirm three newly detected extended sources as new SNRs, while we propose 13 extended sources as new X-ray SNR candidates. We also present the analysis of the follow-up XMM-Newton observation of MCSNR J0456–6533 discovered with eROSITA. Among the new candidates, we propose J0614–7251 (4eRASSU J061438.1–725112) as the first X-ray SNR candidate in the outskirts of the LMC.
THE THREE HUNDRED project: Estimating the dependence of gas filaments on the mass of galaxy clusters
Authors: Santoni Sara , De Petris Marco , Yepes Gustavo , Ferragamo Antonio , Bianconi Matteo , Gray Meghan E. , Kuchner Ulrike , Pearce Frazer R. , Cui Weiguang , Ettori Stefano
Published: November 2024

Context. Galaxy clusters are located in the densest areas of the universe and are intricately connected to larger structures through the filamentary network of the cosmic web. In this scenario, matter flows from areas of lower density to higher density. As a result, the properties of galaxy clusters are deeply influenced by the filaments that are attached to them, which are quantified by a parameter known as connectivity.

Aims. We explore the dependence of gas-traced filaments connected to galaxy clusters on the mass and dynamical state of the cluster. Moreover, we evaluate the effectiveness of the cosmic web extraction procedure from the gas density maps of simulated cluster regions.

Methods. Using the DisPerSE cosmic web finder, we identify filamentary structures from the 3D gas particle distribution in 324 simulated regions of 30 h−1 Mpc side from THE THREE HUNDRED hydrodynamical simulation at redshifts z = 0, 1, and 2. We estimate the connectivity at various apertures for ∼3000 groups and clusters spanning a mass range from 1013 h−1 M⊙ to 1015 h−1 M⊙. Relationships between connectivity and cluster properties like radius, mass, dynamical state, and hydrostatic mass bias are explored.

Results. We show that the connectivity is strongly correlated with the mass of galaxy clusters, with more massive clusters being on average more connected. This finding aligns with previous studies in the literature, both from observational and simulated datasets. Additionally, we observe a dependence of the connectivity on the aperture at which it is estimated. We find that connectivity decreases with cosmic time, while no dependencies on the dynamical state and hydrostatic mass bias of the cluster are found. Lastly, we observe a significant agreement between the connectivity measured from gas-traced and mock-galaxy-traced filaments in the simulation.
The counter-rotating stellar core of NGC 4494
Authors: Coccato L. , Morelli L. , Pizzella A. , Corsini E. M. , Cuomo V.
Published: November 2024

Context. Kinematically decoupled cores (KDCs) are often found in the centers of early-type galaxies.

Aims. We aim to investigate the kinematics, structure, and stellar populations of the KDC residing in the early-type galaxy NGC 4494 to understand its formation.

Methods. We used long-slit spectroscopic data obtained with the FORS2 instrument on the VLT to measure the stellar kinematics and stellar populations. We performed a spectroscopic decomposition to disentangle the properties of the KDC from those of the host galaxy and construct models of the observed rotation curve.

Results. The rotation curve is characterized by two symmetric dips at |R| = 6″, where the rotation velocity drops to zero. Contrary to previous studies that explained the decoupled structure as a rapidly co-rotating disk, our analysis clearly shows that it is a counter-rotating component. A counter-rotating core is indeed needed to reproduce the observed dip in the velocity curve. The properties of the stellar populations of the decoupled core and the main galaxy are very similar: old stars (12−13 Gyr) with slightly super-solar metallicities (0 < [Z/H]< 0.15 dex) and α-enhanced (0 < [α/Fe]< 0.15 dex).

Conclusions. Our results indicate that the counter-rotating component is a disk of about 1 kpc in diameter that is obscured by dust in the central 0.12 kpc. The properties of its stellar populations suggest that it formed from the same material as the main stellar body of the host galaxy. This could have happened via internal processes such as the precession of a pre-existing rotating core, or, alternatively, via gas accretion in retrograde orbits followed by star formation. In the latter scenario, the accretion event occurred almost simultaneously with the formation of the galaxy, using material that had the same composition as the gas from which the stars in the main body of the galaxy were formed.
From Quaternary Science to Earth System Science
Authors: An Zhisheng
Published: November 2024

This article details how AN Zhisheng and his colleagues, through decades of dedicated research, began with the study of loess in China and integrated it with climatic and environmental researches. AN and his team developed a novel research approach to identifying the dynamics of changes of natural environments, including loess environment in East Asia. Their work has not only highlighted the global significance of Chinese loess as a record for global climate change, but also led to the formulation of the monsoon control theory regarding environmental changes in East Asia, as well as insights into Asian and global monsoon dynamics. The paradigm shift from a singular discipline of Quaternary science into a comprehensive Earth system science has happened. Their contributions have been instrumental in promoting sustainable development of the society in the Chinese Loess Plateau and western China.
Phase of the order parameter in a symmetric superconductor–barrier–superconductor junction
Authors: Zubov E. E.
Published: November 2024

Within the framework of the self-consistent effective field approximation of the time-dependent perturbation theory, an influence of the electron tunneling on parameter order, spectral, and transport properties in a hybrid “superconductor–barrier–superconductor” structure are considered. The concept of spontaneous and induced phases of order parameter is entering. The areas of the coherent and noncoherent single-particle electron excitations have been determined. The coherent spectrum near the energy gap is realized without the phase difference of the superconductors order parameters only. The temperature dependencies of the Josephson supercurrent with different barrier transparencies are studied. The calculated Josephson dc supercurrent at a zeroth temperature in a Sn–barrier–Sn structure depends significantly on the transparency of the barrier as well as the spontaneous phase.
Superconducting coupling through inhomogeneous magnetization in Bi2Sr2Ca2Cu3Oy/La2/3Ca1/3MnO3 nanocomposite
Authors: Krivoruchko V. N. , Tarenkov V. Yu. , Belogolovskii M.
Published: November 2024

Propagation of spin-singlet Cooper pairs from a conventional superconductor into a ferromagnetic material over comparatively long distances was explained by the emergence at their interface of equal-spin triplet pairing that is no longer subject to pair-breaking mechanisms within magnetic counterparts. This phenomenon is produced by interfacial magnetic inhomogeneity and most spectacularly manifests itself in all-oxide heterostructures involving cuprates and manganites. In contrast to previous works, mostly devoted to bilayers of these materials, we are studying the long-penetration effect in random binary nanocomposites formed by half-metallic La2/3Ca1/3MnO3 nanoparticles and micro-sized particles of a d-wave superconductor Bi2Sr2Ca2Cu3Oy. With point-contact spectro­scopy, we revealed the presence of two superconducting gaps, namely the gap Δd in the cuprate granules partly suppressed due to the proximity effect and the proximity-induced gap in the spectrum of excitations of equal-spin triplet Cooper pairs. External magnetic fields, which tend to align the magnetizations at and near the interfaces, significantly suppressed the features of the superconducting origin including a symmetrical periodic structure at energies less than the energy Δd, while the conductivity in the normal state changes only slightly. Like related oxide bilayers, it enables control of the supercurrent transfer across hybrid nanocomposite super-spintronic devices by tuning the degree of magnetic inhomogeneity.
The effect of all-round compression on the critical temperature of Y0.66Pr0.34Ba2Cu3O7–δ single crystals
Authors: Khadzhai G. Ya. , Komisarov A. O. , Vragov O. Yu. , Kovrygin V. O. , Vovk R. V.
Published: November 2024

In the present work, the effect of all-round compression up to 10 kbar on the in-plane electrical resistivity of well-structured Y0.66Pr0.34Ba2Cu3O7–δ (δ < 0.15, Тс ≈ 51.8 K, ΔТс ≈ 2 K) single crystals has been investigated. In contrast to the samples with low praseodymium doping (x ≈ 0.05), the application of all-round compression to the samples with medium praseodymium doping (х ≈ 0.34) leads to an increase in the baric derivative dТс/dP by more than two times. It was found that, in contrast to polycrystalline samples, there was no change in the sign of the baric derivatives dТс/dP. The applicability of the well-known McMillan formula to explain the effect of all-round compression on Тс is discussed.
On the periodic behavior of the generalized Chazy differential equation
Authors: Zhuang Ziwei , Liu Changjian , Luo Jiahui
Published: November 2024

We consider the periodic behavior of the generalized Chazy differential equation x⃛+|x|qx¨+k|x|qxx˙2=0, where q is a positive integer and k is a real number. We give a pure analysis on the existence of non-trivial periodic solutions for k=q+1 and the non-existence of them for k≠q+1. Our method is based on considering the projections of the orbits onto the phase plane (x,x˙). We find that a non-trivial periodic solution of the equation is equivalent to a closed curve formed by two equilibrium points and two orbits with some specific constraints in the corresponding planar system and that the existence of such closed curves can be obtained by the existence of real zeros of some returning map. Our conclusion covers all q, which completes a recent result.
Surface properties of anode materials as an indicator of dendrite growth
Authors: Guskov Timur , Mazitov Arslan , Kruglov Ivan
Published: November 2024

Anode material is a crucial component of Li-ion battery influencing electrochemical performance and overall efficiency of energy storage and conversion systems. In particular, its surface properties are of decisive importance. In this work, using density functional theory in conjunction with machine-learning interatomic potentials, we calculated diffusion rates of lithium adatom and its adsorption energy on lithium, copper, and lithium–indium alloy surfaces. We compared calculated properties of chosen materials to estimate their propensity to favor dendrite growth. Our results show that copper is a less favorable environment for dendrite formation than lithium itself, while the lithium-indium alloy has the worst surface properties, which can most likely lead to the formation of dendrites. The performed set of calculations can be used as an initial assessment of the suitability of the material for the role of anode.
Pulse current injection platform with consecutive early-time and intermediate-time high-altitude electromagnetic pulse conducted currents for immunity test of electrical equipment
Authors: Zhang Dao-zhong , Xie Yan-zhao , Zhou Yi , Wu Yu-ying , Zhang Yun-peng
Published: November 2024

High-altitude electromagnetic pulse (HEMP) has attracted considerable attention for its influence on electrical equipment. HEMP is divided into three parts: early time HEMP (E1), intermediate-time HEMP (E2), and late-time HEMP (E3). Most studies focused on E1 alone, while few investigated others. However, the electrical equipment may be disturbed by more than one part since these three parts co-exist in a HEMP environment. The pulse current injection (PCI) test is an effective immunity test method for evaluating the sensitivity and susceptibility of electrical equipment. To investigate the responses of electrical equipment excited by the consecutive E1 and E2 and compare with those under the individual E1 or E2, this paper builds a PCI platform that can carry out PCI tests with the consecutive E1 and E2 conducted current. To output the E1 current and the E2 current consecutively, which exhibit significant differences in the rise time (20 ns and 1.5 μs), peak current (2500 and 250 A), and full width at half maximum (FWHM, 500–550 ns and 3–5 ms), an E1&E2 coupler with a fast-closing high-current trigger switch is designed in this paper. Finally, some 10-kV epoxy insulators are tested in the developed platform, which shows the capacity of the proposed platform to test the immunity of electrical equipment with the consecutive E1 and E2 conducted current.
Simulation and modeling of wind farms in baroclinic atmospheric boundary layers
Authors: Kasper J. H. , Stieren A. , Stevens R. J. A. M.
Published: November 2024

The performance of wind farms strongly depends on the prevailing atmospheric conditions. We investigated how baroclinicity, caused by horizontal temperature gradients in the atmosphere, affects wind farm performance and wake recovery, using large eddy simulations. Baroclinicity impacts the power generation in the entrance region of a wind farm by modifying atmospheric conditions around turbine height, such as the turbulence intensity. The power production of downstream turbines is also affected by baroclinicity, as it alters the kinetic energy available for entrainment above the wind farm. Furthermore, our findings reveal that the recovery of wind farm wakes is governed by wake expansion, controlled by atmospheric turbulence intensity, and by an upward shift of the wake velocity deficit, which is driven by vertical velocity shear. These insights have been incorporated into a novel engineering model designed to predict large-scale wake recovery behind wind farms in both barotropic and baroclinic conditions.
Score-driven exponential random graphs: A new class of time-varying parameter models for temporal networks
Authors: Di Gangi D. , Bormetti G. , Lillo F.
Published: November 2024

Motivated by the increasing abundance of data describing real-world networks that exhibit dynamical features, we propose an extension of the exponential random graph models (ERGMs) that accommodates the time variation of its parameters. Inspired by the fast-growing literature on dynamic conditional score models, each parameter evolves according to an updating rule driven by the score of the ERGM distribution. We demonstrate the flexibility of score-driven ERGMs (SD-ERGMs) as data-generating processes and filters and show the advantages of the dynamic version over the static one. We discuss two applications to temporal networks from financial and political systems. First, we consider the prediction of future links in the Italian interbank credit network. Second, we show that the SD-ERGM allows discriminating between static or time-varying parameters when used to model the U.S. Congress co-voting network dynamics.
Adiabatic state conversion for (a)cyclic non-Hermitian quantum Hamiltonians of generalized functional form
Authors: Nye Nicholas S. , Kantartzis Nikolaos V.
Published: November 2024

In the present paper, we aim to firmly establish the adiabatic properties of two-level non-Hermitian quantum structures evolving along generalized (open/acyclic or closed/cyclic) paths in parameter space. Analytical solutions in terms of Airy and modified Bessel functions have been retrieved for linear and hyperbolic temporal dependencies in parity-time-symmetric-like systems, which were subsequently studied in the slowly varying limit to show conversion to one of the instantaneous eigenstates. Such a mode switching behavior is found to be an identifying feature of dissipative quantum settings, whether they evolve along cyclic or acyclic trajectories, and this has been proven in our paper by separately analyzing the dynamics of (i) the ratio of the state vector components, via a variant of the Möbius transformation, and (ii) the complex probability amplitudes, through a systematic inspection of the mode population equations. In the latter instance, it was furthermore shown that the identity of the eigenstate, to which the quantum arrangement transitions, depends highly on the magnitude of the adiabatic rate β. Along these lines, the concepts of the instantaneous(D) and averagely(Dav)dominant eigenstates are brought forth, while a reconfigurable photonic switch is also proposed, which can convert either to the D or to the Dav modes based on the total period of evolution. Finally, we apply our findings in the case of closed parametric paths to demystify the recently reported symmetric and asymmetric state conversion effects and additionally demonstrate that operation at or near exceptional points does not qualitatively affect the conclusions of the current investigation.
Ab initio calculations of molecular double Auger decay rates
Authors: Kolorenč Přemysl
Published: November 2024

We report on the application of the recently developed Fano-ADC(2,2) method to compute total and partial Auger decay widths of molecular core–hole states, including explicit evaluation of double Auger decay branching ratios. The method utilizes the fast-convergent intermediate state representation to construct many-electron wave functions and is readily applicable to atoms, molecules, and clusters. The ADC(2,2) scheme describes the initial and final states of the normal Auger decay consistently up to the second order of perturbation theory. In addition, excitations with two electrons in the continuum provide access to three-electron decay modes. The method yields decay widths and the Auger electron spectra in excellent agreement with the experiment, demonstrating the high accuracy of partial widths. The average relative error of double Auger decay branching ratios compared to available experimental data is about 30%, which should be evaluated as an excellent result considering the universality of the method, the complexity of the double decay process, and the neglection of nuclear motion in this study.
Thermal characterization of Ge-rich GST thin films for phase change memories by Raman thermometry
Authors: Patil Akash , Le-Friec Yannick , Roussel Pascal , Deblock Yves , Jeannot Simon , Boivin Philippe , Dubois Emmanuel , Robillard Jean-François
Published: November 2024

Doped GeSbTe (GST)-based phase change materials are of growing interest due to their ability to enable high-temperature data retention for embedded memory applications. This functionality is achieved through Ge enrichment and addition of dopants such as N and C in stoichiometries such as GST-225, which improve the crystallization temperature and thermal phase stability. In this study, we examine the effect of these dopants on thermal conductivity using Raman thermometry. We report the temperature-dependent thermal conductivity of the amorphous and crystalline phases of Ge-rich GeSbTe (GGST) and Ge-rich GeSbTe N-doped (GGSTN) thin films. The results reveal a surprising temperature dependence of the thermal conductivity of the crystalline phase of GGST and GGSTN, a phenomenon not typically observed for GST-based materials. Additionally, enrichment of Ge and subsequent N-doping result in reduced thermal conductivity, which can benefit the power consumption of phase change memories. From a characterization perspective, Raman thermometry has been developed as a technique for simultaneous structural and thermal characterization of GST-based materials.
Mesoscale eddy in situ observation and characterization via underwater glider and complex network theory
Authors: Guo Wei , Li Zezhong , Sun Xinlin , Zhou Yatao , Juan Rongshun , Gao Zhongke , Kurths Jürgen
Published: November 2024

Mesoscale eddies have attracted increased attention due to their central role in ocean energy and mass transport. The observations of their three-dimensional structure will facilitate the understanding of nonlinear eddy dynamics. In this paper, we propose a novel framework, the mesoscale eddy characterization from ordinal modalities recurrence networks method (MeC-OMRN), that utilizes a Petrel-II underwater glider for in situ observations and vertical structure characterization of a moving mesoscale eddy in the northern South China Sea. First, higher resolution continuous observation profile data collected throughout the traversal by the underwater glider are acquired and preprocessed. Subsequently, we analyze and compute these nonlinear data. To further amplify the hidden structural features of the mesoscale eddy, we construct ordinal modalities sequences rich in spatiotemporal characteristics based on the measured vertical density of the mesoscale eddy. Based on this, we employ ordinal modalities recurrence plots (OMRPs) to depict the vertical structure inside and outside the eddy, revealing significant differences in the OMRPs and the unevenness of density stratification within the eddy. To validate our intriguing findings from the perspective of complex network theory, we build the multivariate weighted ordinal modalities recurrence networks, through which network measures exhibit a more random distribution of vertical density stratification within the eddy, possibly due to more intense vertical convection and oscillations within the eddy's seawater micelles. These framework and intriguing findings are anticipated to be applied to more data-driven in situ observation tasks of oceanic phenomena.
Application of graph neural network in computational heterogeneous catalysis
Authors: Jiao Zihao , Liu Ya , Wang Ziyun
Published: November 2024

Heterogeneous catalysis, as a key technology in modern chemical industries, plays a vital role in social progress and economic development. However, its complex reaction process poses challenges to theoretical research. Graph neural networks (GNNs) are gradually becoming a key tool in this field as they can intrinsically learn atomic representation and consider connection relationship, making them naturally applicable to atomic and molecular systems. This article introduces the basic principles, current network architectures, and datasets of GNNs and reviews the application of GNN in heterogeneous catalysis from accelerating the materials screening and exploring the potential energy surface. In the end, we summarize the main challenges and potential application prospects of GNNs in future research endeavors.
Pulses in singularly perturbed reaction-diffusion systems with slowly mixed nonlinearity
Authors: Chen Yuanxian , Cai Yuhua , Shen Jianhe
Published: November 2024

This article is concerned with the existence and spectral stability of pulses in singularly perturbed two-component reaction-diffusion systems with slowly mixed nonlinearity. In this paper, the slow nonlinearity is referred to be “mixed” in the sense that it is generated by a trigonometric function multiplied by a power function. We demonstrate via geometric singular perturbation theory that this model can support both the single-pulse and the double-hump solutions. The presence of the slowly mixed nonlinearity complicates the stability analysis on pulses, since the conditions that govern their stability can no longer be explicitly computed. We remove this difficulty by introducing the hypergeometric functions followed by a comparison theorem. By doing so, the “slow–fast” eigenvalues can be determined via the nonlocal eigenvalue problem method. We prove that the double-hump solution is always unstable, while the single-pulse solution can be stable under certain parameter conditions.
A simple approach to rotationally invariant machine learning of a vector quantity
Authors: Martinka Jakub , Pederzoli Marek , Barbatti Mario , Dral Pavlo O. , Pittner Jiří
Published: November 2024

Unlike with the energy, which is a scalar property, machine learning (ML) prediction of vector or tensor properties poses the additional challenge of achieving proper invariance (covariance) with respect to molecular rotation. For the energy gradients needed in molecular dynamics (MD), this symmetry is automatically fulfilled when taking analytic derivative of the energy, which is a scalar invariant (using properly invariant molecular descriptors). However, if the properties cannot be obtained by differentiation, other appropriate methods should be applied to retain the covariance. Several approaches have been suggested to properly treat this issue. For nonadiabatic couplings and polarizabilities, for example, it was possible to construct virtual quantities from which the above tensorial properties are obtained by differentiation and thus guarantee the covariance. Another possible solution is to build the rotational equivariance into the design of a neural network employed in the model. Here, we propose a simpler alternative technique, which does not require construction of auxiliary properties or application of special equivariant ML techniques. We suggest a three-step approach, using the molecular tensor of inertia. In the first step, the molecule is rotated using the eigenvectors of this tensor to its principal axes. In the second step, the ML procedure predicts the vector property relative to this orientation, based on a training set where all vector properties were in this same coordinate system. As the third step, it remains to transform the ML estimate of the vector property back to the original orientation. This rotate–predict–rotate (RPR) procedure should thus guarantee proper covariance of a vector property and is trivially extensible also to tensors such as polarizability. The RPR procedure has an advantage that the accurate models can be trained very fast for thousands of molecular configurations, which might be beneficial where many training sets are required (e.g., in active learning). We have implemented the RPR technique, using the MLatom and Newton-X programs for ML and MD, and performed its assessment on the dipole moment along MD trajectories of 1,2-dichloroethane.
Suppression of the coffee-ring effect using a contact-angle radial-band-patterned substrate: A lattice Boltzmann study
Authors: Lee Hee Min , Lee Joon Sang
Published: November 2024

The coffee-ring effect is a phenomenon in which particles are deposited on a contact line during the evaporation of a particle-laden sessile droplet. In this study, a patterned contact-angle substrate was designed using lattice Boltzmann simulation to suppress the coffee-ring effect. The simulation model was a combination of multiphase flow, heat transfer, and nanoparticle dynamics models. The simulation results repeatedly showed the contact line of the evaporating droplet on the patterned substrate during pinning and depinning. The contact line dynamics also affected the particle distribution. A multi-ring pattern was observed on the patterned substrate compared to the particle distribution on a substrate with a constant contact angle. This was a result of the repeated pinning and depinning of the contact line, and it was compared using the particle uniformity index presented in this study. This revealed a particle distribution that was 4.24-fold more uniform than the coffee-ring pattern. In subsequent pattern optimization, the particle uniformities of 51 cases with different geometries were measured. The pinning time in each patterned area of the case with the most uniform particle distribution was measured. Other factors, in addition to the pinning time, affected particle deposition, and the internal flow of the droplet was further analyzed. Within the droplet, the Marangoni flow generally decreased with continuous oscillations, whereas the capillary flow increased sharply in the region with a receding angle of 45°. This sharp increase in the capillary flow caused the particles trapped in the Marangoni flow to escape and increased the deposition rate.
Drift wave KdV equation creates dip solitons
Authors: Saleem H.
Published: November 2024

It is shown that the Korteweg de-Vries (KdV) equation can be derived for pure drift waves propagating in the direction perpendicular to both the density gradient and the external magnetic field. The form of the KdV equation turns out to be similar to that obtained for ion acoustic waves but with a negative potential, which gives electrostatic dip solitons.
Numerical simulation study on ice breaking by a submerged water jet
Authors: Xue Yanzhuo , Wang Xin , Yuan Guangyu , Ni Bao-Yu , Xu Xuesong , Song Jiarui
Published: November 2024

Based on the computational fluid dynamics-discrete element method (CFD-DEM) coupling method, numerical analysis of ice breaking by a submerged water jet is carried out. The submerged water jet model is established by the finite volume method (FVM) in the CFD method, while the ice plate model is composed of multi-layer spherical DEM particles bonded in a hexagonal closest packing manner. The results of numerical simulation are consistent with those of experiments, including the submerged jet morphology, stagnation pressure of the water jet, and different breaking cases of ice plate, which validates the numerical model. Based on the submerged jet model, the effects of the target distance, nozzle inlet velocity, and impact angle on the impacting load of the submerged jet are studied. Furthermore, through CFD-DEM coupling model, the mechanism of ice breaking by the submerged water jet is discussed, that is, the initial radial cracks first appear on the upper surface of the ice plate under the action of reflected expansion wave and the overall bending caused by jet loads, and then the circumferential cracks appear on the lower surface of the wedge ice plate under the bending action of water jet loads. Moreover, the effects of the water jet impact velocity and ice plate thickness on the ice breaking are also investigated. This paper studies the ice-breaking mechanism of the submerged high-speed water jet and presents a numerical model for the analysis of the interaction between the submerged water jet and ice plate.
The effect of pressure in the crystal and magnetic structure of FeWO4
Authors: Fabelo Oscar , Gonzalez-Platas Javier , Savvin Stanislav , Botella Pablo , Errandonea Daniel
Published: November 2024

The temperature dependence of the structural and magnetic properties of wolframite-type FeWO4 was studied in situ by high-pressure neutron diffraction. Neutron diffraction measurements were performed with the XtremeD instrument at the Institut Laue-Langevin up to a maximum pressure of 8.7(4) GPa and a minimum temperature of 30.0(5) K. The diffraction data were analyzed via Rietveld refinements. We found that despite producing a contraction of 5% of the volume, the maximum pressure applied in this study does not modify the Shubnikov space group below magnetic order. However, the orientation of magnetic moments and the Néel temperature are slightly modified with the pressure, which is expected according to the preexistent understanding of magnetism in wolframites. We also determined a pressure–volume equation of state of FeWO4 at 300 K, which is compared with previous x-ray diffraction studies and density-functional theory calculations.
Effect of strain mode on the transverse thermoelectric effect of inclined La1−xCaxMnO3 thin films
Authors: Chen Xi , Tao Bowan , Zhao Ruipeng , Yang Kai , Yu Yuhang , Tian Hongbo , Zhu Hongxu , Li Zhenzhe , Xie Tian , Zhao Mingyuan , Xia Yudong
Published: November 2024

Strain engineering is an important way to control the physical properties of manganite thin films. Here, the effect of strain mode on the transverse thermoelectric (TTE) effect of inclined La1xCaxMnO3 (LCMO) thin films is investigated. The compressive strain enhances the electrical conductivity of the LCMO thin film, resulting in larger laser-induced voltage and faster response speed, which is suitable for high-energy pulse laser detection. Compared to that, the LCMO thin film on the STO substrate is ideal for heat-flux detection due to higher heat-flux sensitivity originating from lower conductivity. Still, it also has to withstand the loss of response speed. Moreover, it is first observed that the TTE voltage polarity of the LCMO thin film changes under different strain states. The measured results of LCMO thin films deposited LaAlO3 (LAO) substrate buffered with the SrTiO3 (STO) thin film and STO substrate buffered with the LAO thin film strongly support that the above results are indeed caused by the lattice strain. This work may be suitable for other material systems to modulate thermoelectric transport anisotropy and the TTE effect by strain.
Temporal map of electromagnetic emissions produced by laboratory atmospheric discharges
Authors: Parkevich E. V. , Shpakov K. V. , Baidin I. S. , Rodionov A. A. , Khirianova A. I. , Bolotov Ya.K. , Ryabov V. A.
Published: November 2024

We exhaustively investigate the temporal correlations between the ultrahigh-frequency (of the order of 1–6 GHz), very high-frequency (of the order of 10–100 MHz), and x-ray (photons with energies from 5 keV to 1 MeV) emissions together with the optical emissions in the near-infrared (within 700–1100 nm) and near-ultraviolet (within 300–400 nm) wavelength regions. The emissions are produced by a laboratory atmospheric discharge developing in an 55 cm air gap at voltages up to 1 MV. When registering various electromagnetic emissions, the discharge current and voltage are measured, as well as nanosecond imaging of the discharge evolution in its own glow is performed. The spatiotemporal localization of the discharge regions associated with the x-ray generation is carried out by employing the group of fast scintillation detectors, and the evolution of plasma structures during the x-ray generation is traced. A chronological map is constructed providing an in-depth understanding of the temporal character and correlations of various electromagnetic emissions. The map allows one to analyze fast ionization processes occurring in the gas-discharge medium and triggering the generation of the corresponding emissions. The generation mechanisms of the considered emissions in an extended high-voltage discharge are discussed. The findings can be helpful in revealing the sources of various electromagnetic emissions accompanying the formation of laboratory and atmospheric discharges.
An improved smoothed particle hydrodynamics method for the coupled simulation of fixed net structures in currents and waves
Authors: Xu Yang , Sun Peng-Nan , Huang Xiao-Ting , Liu Pu-Zhen
Published: November 2024

In the present paper, a numerical model, named smoothed particle hydrodynamics (SPH)-net model, is proposed for the coupled simulation of fixed net structures in currents and waves based on the coupling between the SPH method and screen model. The fluid is solved by the SPH method and the net structures are handled by the screen model, both of which are represented by a number of Lagrangian particles. A coupling algorithm between the SPH method and screen model is derived based on the momentum disturbance, which allows for accurate simulation of interactions between net structures and fluid. Thanks to the quasi-static assumption of the screen model, the proposed model can both handle the net structures in currents and waves. To validate the SPH-net model, numerical simulations were conducted on three distinct cases: fixed net panels in currents, a fixed net cage in currents, and a fixed net panel in the regular wave. The comparison of hydrodynamic forces on the net between the numerical results and experimental data demonstrates that the proposed SPH-net model has accuracy and reliability in predicting the hydrodynamic forces acting on fixed net structures in currents and regular waves.
Coupling analysis between wave resonance in the moonpool and heave motion of the twin hulls with mooring effect
Authors: Jiang Sheng-Chao , Lan Jun-Jie , Bai Wei , Huang Yong-Qiang
Published: November 2024

Fluid resonance in the moonpool formed by two identical rectangular hulls in water waves is investigated by employing the Computational Fluid Dynamics (CFD) package OpenFOAMⓇ. The influence of vertical stiffness on the behavior of moonpool resonance coupling with the heave motion response is presented. Numerical simulations show that the free surface oscillation in the moonpool exhibits a two-peak variation with the incident wave frequency, defined as the first and second peak frequencies. A local Keulegan–Carpenter (KC) number is introduced for describing the influence of fluid viscosity and flow rotation on the fluid resonance and heave motion resonance. At the first peak frequency, the free surface oscillation and heave motion response show an in-phase relationship, where increase in the vertical stiffness can increase the relative motion between them. This finally leads to an increase in the KC number, indicating the increased effect of energy dissipation with increase in the vertical stiffness. At the second peak frequency with an out-of-phase relationship between the free surface oscillation and heave motion response, the variation of the KC number is not sensitive to the vertical stiffness. Correspondingly, the influence of energy dissipation is not strongly dependent on the vertical stiffness.
Application of the thermal shock response spectrum (TSRS) methodology to various forms of heat sources by pulse thermography and comparison by using a rotating line scan contour search algorithm
Authors: Yagdjian Harutyun , Lecompagnon Julien , Hirsch Philipp , Ziegler Mathias , Gurka Martin
Published: November 2024

In this paper, we propose a novel contour search algorithm (CSA) for image processing. Its efficacy is evaluated through a comparative analysis with established techniques such as Canny Edge and Snakes: Active contour models, utilizing infrared thermography (IRT) images. Based on the new CSA, we investigate the influence of different pulse shapes on the IRT post-processing methodology, particularly focusing on the thermal shock response spectrum (TSRS), using two different heat sources: xenon flash lamps and a laser. Moreover, this allows for a more precise quantitative comparison of the TSRS with existing IRT post-processing techniques, including pulse phase thermography and thermal signal reconstruction, concerning the detection of defects in composite materials, particularly in carbon fiber-reinforced polymer. A quantitative comparison was performed using the Tanimoto criterion and signal-to-noise ratio. A more detailed analysis is conducted to identify inherent limitations and potential benefits of the new TSRS methodology. We further investigate and experimentally confirm our previous finding on the qualitative correlation between the one-dimensional thermal N-layer model and test data from the TSRS optimization process for defect determination. This correlation can eliminate the time-consuming optimization step, making TSRS a more attractive alternative to common IRT methods and enhancing the quantitative description of defects.
Thermodynamic analysis of superhydrophobicity on three-dimensional hexagonal microcolumn surfaces
Authors: Wang Yinfeng , Wang Yubo , Xue Yiqing , Guo Bin , Yuan Bo , Liang Wenyan
Published: November 2024

Superhydrophobic surfaces are crucial in many applications because of their unique wetting properties. The present study proposes a three-dimensional thermodynamic model, inspired by the morphologies of springtails' skin and mosquitoes' compound eyes in their natural habitats. The model uses thermodynamic principles to analyze the superhydrophobicity of hexagonal columnar microstructures on solid surfaces. From a theoretical standpoint, the variation rules of normalized free energy and normalized free energy barrier with contact angle in two distinct states of wetting were examined. It then calculated the equilibrium contact angle and contact angle hysteresis using the model. The model elucidates the effects of microcolumn height and center distance on free energy and free energy barriers, as well as the transition between composite and non-composite states. Furthermore, it provides the criterion for the transition between the two wetting states in thermodynamic analysis and theoretical equations. Additionally, observations were conducted on the surface of the rough structure. The thermodynamic analysis and theoretical equation calculations of this model facilitate the design of geometric parameters for rough surfaces. The findings provide a reference point for the design of superhydrophobic surfaces with a stable wetting state.
Orbital entanglement and the double d-shell effect in binary transition metal molecules
Authors: Lampert Julianne S. , Krogmeier Timothy J. , Schlimgen Anthony W. , Head-Marsden Kade
Published: November 2024

Accurate modeling of transition metal-containing compounds is of great interest due to their wide-ranging and significant applications. These systems present several challenges from an electronic structure perspective, including significant multi-reference characters and many chemically relevant orbitals. A further complication arises from the so-called double d-shell effect, which is known to cause a myriad of issues in the treatment of first-row transition metals with both single- and multi-reference methods. While this effect has been well documented for several decades, a comprehensive understanding of its consequences and underlying causes is still evolving. Here, we characterize the second d-shell effect by analyzing the information entropy of correlated wavefunctions in a periodic series of 3d and 4d transition metal molecular hydrides and oxides. These quantum information techniques provide unique insight into the nuanced electronic structure of these species and are powerful tools for the study of weak and strong correlations in the transition metal d manifold.
Effect of non-additive mixing on entropic bonding strength and phase behavior of binary nanocrystal superlattices
Authors: Quintela Matos Isabela , Escobedo Fernando A.
Published: November 2024

Non-additive mixing plays a key role in the properties of molecular fluids and solids. In this work, the potential for athermal order–disorder phase transitions is explored in non-additive binary colloidal nanoparticles that form substitutionally ordered compounds, namely, for equimolar mixtures of octahedra + spheres, which form a CsCl lattice compound, and cubes + spheres, which form a NaCl crystal. Monte Carlo simulations that target phase coexistence conditions were used to examine the effect on compound formation of varying degrees of negative non-additivity created by component size asymmetry and by size-tunable indentations in the polyhedra’s facets, intended to allow the nestling of neighboring spheres. Our results indicate that the stabilization of the compound crystal requires a relatively large degree of negative non-additivity, which depends on particle geometry and the packing of the relevant phases. It is found that negative non-additivity can be achieved in mixtures of large spheres and small cubes having no indentations and lead to the athermal crystallization of the NaCl lattice. For similarly sized components, athermal congruent transitions are attainable and non-additivity can be generated through indentations, especially for the cubes + spheres system. Increasing indentation leads to lower phase coexistence free energy and pressure in the cubes + spheres system but has the opposite effect in the octahedra + spheres system. These results indicate a stronger stabilizing effect on the athermal compound phase by the cubes’ indentations, where a deeper nestling of the spheres leads to a denser compound phase and a larger reduction in the associated pressure-volume free-energy term.
A short trajectory is all you need: A transformer-based model for long-time dissipative quantum dynamics
Authors: Herrera Rodríguez Luis E. , Kananenka Alexei A.
Published: November 2024

In this Communication, we demonstrate that a deep artificial neural network based on a transformer architecture with self-attention layers can predict the long-time population dynamics of a quantum system coupled to a dissipative environment provided that the short-time population dynamics of the system is known. The transformer neural network model developed in this work predicts the long-time dynamics of spin-boson model efficiently and very accurately across different regimes, from weak system–bath coupling to strong coupling non-Markovian regimes. Our model is more accurate than classical forecasting models, such as recurrent neural networks, and is comparable to the state-of-the-art models for simulating the dynamics of quantum dissipative systems based on kernel ridge regression.