bluuebunny/crossref_metadata_2025 huggingface dataset:
Statistical theory of fluids confined in quenched disordered porous media
Authors: Yadav Mamta , Singh Ankit , Singh Yashwant
Published: May 2024

We develop a theory to calculate structural correlations and thermodynamic properties of a fluid confined in a random porous solid medium (matrix). We used density functional formalism to derive an annealed averaged expression for the density profile and excess free energy of fluid arising due to random fields of a particular realization of the matrix. After performing the second average over the quenched-disordered variables, the excess free energy is organized to give one- and two-body potentials for fluid particles. The average over disorder reduces the system to an effective one-component system of fluid in which particles feel one-body (external) potential and interact via effective pair potential. The effective pair potential is a sum of the bare (the one in the pure fluid) and the matrix-induced potential. The resulting partition function involves only fluid variables. Equations are derived for fluid–fluid and fluid–matrix correlation functions and for free energy, pressure, and chemical potential of the fluid. The theory is applied to a model system of hard spheres and results for the effective pair potential, correlation functions, and thermodynamic properties are reported. The effective pair potential is found to be attractive at the contact and develops a repulsive peak before decaying to zero. Results for pair correlation function and structure factor are compared with simulation results for several fluid densities at two matrix densities. In all the cases, a very good agreement has been found.
On the effect of flux-surface shaping on trapped-electron modes in quasi-helically symmetric stellarators
Authors: Gerard M. J. , Pueschel M. J. , Geiger B. , Mackenbach R. J. J. , Duff J. M. , Faber B. J. , Hegna C. C. , Terry P. W.
Published: May 2024

Using a novel optimization procedure, it has been shown that the Helically Symmetric eXperiment stellarator can be optimized for reduced trapped-electron-mode (TEM) instability [Gerard et al., Nucl. Fusion 63, (2023) 056004]. Presently, with a set of 563 experimental candidate configurations, gyrokinetic simulations are performed to investigate the efficacy of available energy EA, quasi-helical symmetry, and flux-surface shaping parameters as metrics for TEM stabilization. It is found that lower values of EA correlate with reduced growth rates, but only when separate flux-surface shaping regimes are considered. Moreover, configurations with improved quasi-helical symmetry demonstrate a similar reduction in growth rates and less scatter compared to EA. Regarding flux-surface shaping, a set of helical shaping parameters is introduced that show increased elongation is strongly correlated with reduced TEM growth rates, however, only when the quasi-helical symmetry is preserved. Using a newly derived velocity-space-averaged TEM resonance operator, these trends are analyzed to provide insights into the physical mechanism of the observed stabilization. For elongation, stabilization is attributed to geometric effects that reduce the destabilizing particle drifts across the magnetic field. Regarding quasi-helical symmetry, the TEM resonance in the maximally resonant trapping well is shown to increase as the quasi-helical symmetry is broken, and breaking quasi-helical symmetry increases the prevalence of highly resonant trapping wells. While these results demonstrate the limitations of using any single metric as a linear TEM proxy, it is shown that quasi-helical symmetry and plasma elongation are highly effective metrics for reducing TEM growth rates in helical equilibria.
Resonant Auger decay of iodobenzene below the I 4d edge
Authors: Pratt Stephen T. , Jacovella Ugo , Gans Bérenger , Bozek John D. , Holland David M. P.
Published: May 2024

New data are presented on the resonant Auger decay of iodobenzene (C6H5I) in the region of the I 4d−1 ionization threshold. The excited molecules decay by participator and spectator processes to populate single-hole valence states and two-hole, one-particle excited states of the cation, providing new information on the structure of C6H5I+. Excitation of dissociative C6H5I (I 4d5/2,3/2−1)σ* resonances can, in principle, result in ultrafast dissociation to C6H5 + I** and the subsequent autoionization of I**, but no evidence for this process is observed. The results are compared with our recent study of the resonant Auger decay of methyl iodide (CH3I).
Multi-stacked polarization insensitive broadband terahertz metamaterial
Authors: Singh Chouhan Bhagwat , Acharyya Nityananda , Panwar Anuraj , Roy Chowdhury Dibakar , Kumar Gagan
Published: May 2024

In this article, we present a polarization-insensitive terahertz metamaterial designed by stacking resonators capable of providing ultra-wideband terahertz transmissions. Our design includes a square ring resonator situated between two windmill-shaped resonators, separated by a polyimide spacer. We optimized the spacer thickness to achieve a broadband response in transmission. These optimized broadband metamaterial designs were fabricated through multiple steps of the photolithography process. Terahertz time-domain spectroscopy of the fabricated samples indicates broadband terahertz transmission, in agreement with both simulation findings and results calculated from the transmission line model for the multi-layered metamaterial geometry. Our research reveals a strong near-field coupling between resonators, leading to wideband transmission of terahertz waves. The stacking of these metamaterials is crucial in designing broadband bandpass filters and broadband modulators for terahertz photonics while keeping the resonance strength almost intact.
Transient optical properties change and dense plasma dynamics during water breakdown induced by ultrashort laser pulses
Authors: Yang Zhi , Zhang Chong , Ying Kaining , Li Qiuyu , Zhang Hailong , Zhang Hongchao , Lu Jian
Published: May 2024

We propose a nonlinear transient coupling model to study the plasma dynamics during the interaction between ultrashort laser pulses and water. We conduct a quantitative characterization of the transient optical properties, energy deposition, and dense plasma dynamics in water with near-infrared ultrashort laser pulses by simulating the spatiotemporal coupling of the laser field with the plasma while calculating the time-varying relative permittivity. The results show that the free electron density in the dense plasma exceeds ≈1.0×1026 m−3, the plasma will move in the reverse direction of the laser pulse propagation, and the velocity is related to the incident laser intensity. An empirical model is established to quantify this reverse movement of dense plasma in the laser field taking into account the energy deposition. We also validate our coupling model by comparing the breakdown thresholds with experimental results and find excellent agreement.
A bivariational, stable, and convergent hierarchy for time-dependent coupled cluster with adaptive basis sets
Authors: Højlund Mads Greisen , Christiansen Ove
Published: May 2024

We propose a new formulation of time-dependent coupled cluster with adaptive basis functions and division of the one-particle space into active and secondary subspaces. The formalism is fully bivariational in the sense of a real-valued time-dependent bivariational principle and converges to the complete-active-space solution, a property that is obtained by the use of biorthogonal basis functions. A key and distinguishing feature of the theory is that the active bra and ket functions span the same space by construction. This ensures numerical stability and is achieved by employing a split unitary/non-unitary basis set transformation: the unitary part changes the active space itself, while the non-unitary part transforms the active basis. The formulation covers vibrational as well as electron dynamics. Detailed equations of motion are derived and implemented in the context of vibrational dynamics, and the numerical behavior is studied and compared to related methods.
Boric acid-induced preferential deposition of (002) plane for highly stable zinc anode
Authors: Ou Tianzhuo , Cao Qun , Zhang Dongdong , Wu Haiyang , Zhang Lulu , Luo Ding , Qin Jiaqian , Yang Xuelin , Cao Jin
Published: May 2024

Aqueous zinc-ion batteries (ZIBs) hold significant promise in the future energy storage market. However, the uncontrolled growth of zinc dendrites and the occurrence of side reactions severely constrain the practical deployment of ZIBs. To address these challenges, this study suggests incorporating H3BO3 (HBO) as an electrolyte additive into the ZnSO4 electrolyte, with the aim of inducing preferential growth of the (002) plane. HBO molecules selectively adsorb onto the (100) and (101) planes of zinc, promoting the deposition of Zn2+ ions into the (002) plane and resulting in the formation of a uniformly deposited layer while concurrently inhibiting side reactions. The results demonstrate that ZnǁZn symmetric batteries, with the HBO additive, exhibit stable cycling at high current density, achieving a cycling life of 1100 h at 10 and 10 mAh cm−2 as well as 250 h at 50% depth of discharge. Furthermore, the ZnǁVO2 coin cell demonstrates stable cycling for 1700 cycles at 1 A g−1 and 7000 cycles at 5 A g−1. This study presents a promising case for the commercialization of advanced ZIBs.
A new dynamic Monte Carlo method satisfying n-particle diffusion equation with position-dependent diffusion coefficient, free energy, and intermolecular interactions
Authors: Okazaki Susumu
Published: May 2024

A dynamic Monte Carlo (MC) method recently proposed by us [Nagai et al., J. Chem. Phys. 156, 154506 (2022)] to describe single-particle diffusion of a molecule in a heterogeneous space with position-dependent diffusion coefficient and free energy is generalized here to n-particle dynamics, where n molecules diffuse in heterogeneous media interacting via their intermolecular potential. Starting from the master equation, we give an algebraic proof that the dynamic MC transition probabilities proposed here produce particle trajectories that satisfy the n-particle diffusion equation with position-dependent diffusion coefficient D0i(ri), free energy F1i(ri), and intermolecular interactions Vij(ri, rj). The MC calculations based on this method are compared to molecular dynamics (MD) calculations for two-dimensional heterogeneous Lennard-Jones test systems, showing excellent agreement of the long-distance global diffusion coefficient between the two cases. Thus, the particle trajectories produced by the present MC transition probabilities satisfy the n-particle diffusion equation, and the diffusion equation well describes the long-distance trajectories produced by the MD calculations. The method is also an extension of the conventional equilibrium Metropolis MC calculation for homogeneous systems with a constant diffusion coefficient to the dynamics in heterogeneous systems with a position-dependent diffusion coefficient and potential. In the present method, interactions and dynamics of the real systems are coarse-grained such that the calculation cost is drastically reduced. This provides an approach for the investigation of particle dynamics in very complex and large systems, where the diffusing length is of sub-micrometer order and the diffusion time is of the order of milliseconds or more.
Theoretical study of the influence of GaOx interfacial layer on the GaN/SiO2 interface property
Authors: Hattori Shuto , Oshiyama Atsushi , Shiraishi Kenji
Published: May 2024

The spontaneous formation of a Ga-oxide (GaOx) intermediate layer at the GaN/SiO2 interface has been reported during the SiO2 deposition on the GaN substrate. In this study, we have performed first-principles calculations and unveiled atomic and electronic structures of the GaN/SiO2 interface with 1-nm thick GaOx intermediate layer. Our calculations show that the top-layer Ga atoms on the GaN side are terminated with the O atoms on the GaOx side, leading to the clean GaN/GaOx interface and the absence of the electronic state in the midgap region. However, strongly localized states, which are originated from O atoms lone-pair orbitals in the –GaOSi– local structures, emerge in the gap near the valence-band maximum of GaN. These in-gap states become hole traps in GaN MOS devices, leading to a degradation in device controllability and operational speed.
Slender vortex filaments in the Boussinesq approximation
Authors: Rodal Marie , Margerit Daniel , Klein Rupert
Published: May 2024

A model for the motion of slender vortex filaments is extended to include the effect of gravity. The model, initially introduced by Callegari and Ting [“Motion of a curved vortex filament with decaying vortical core and axial velocity,” SIAM J. Appl. Math. 35, 148–175 (1978)], is based on a matched asymptotic expansion in which the outer solution, given by the Biot–Savart law, is matched with the inner solution derived from the Navier–Stokes equations. Building on recent work by Harikrishnan et al. [“On the motion of hairpin filaments in the atmospheric boundary layer,” Phys. Fluids 35, 076603 (2023)], the Boussinesq approximation is applied such that the density variations only enter in the gravity term. However, unlike Harikrishnan et al. [“On the motion of hairpin filaments in the atmospheric boundary layer,” Phys. Fluids 35, 076603 (2023)], the density variation enters at a lower order in the asymptotic expansion and, thus, has a more significant impact on the self-induced velocity of the vortex filament. In this regime, which corresponds to the regime studied by Chang and Smith [“The motion of a buoyant vortex filament,” J. Fluid Mech. 857, R1 (2018)], the effect of gravity is given by an alteration of the core constant, which couples the motion of the filament to the motion within the vortical core, in addition to a change in the compatibility conditions (evolution equations), which determine the leading order azimuthal and tangential velocity fields in the vortex core. The results are used to explain certain properties of buoyant vortex rings, as well as qualitatively explore the impact of gravity on tornado-type atmospheric vortices.
Detachment dynamics of sessile droplets triggered by interaction forces between oil and wall in a microchannel
Authors: He Long , Zhao Fengyu , Shang Xinglong , Lou Rui , Sun Panpan , Song Bingye , Cui Hao , Tao Yiwen
Published: May 2024

Understanding the detachment dynamics of droplets adhered to reservoir walls holds significant importance for the residual oil displacement process in high water-cut oilfields. Existing studies demonstrated that increasing mainstream shear by adjusting displacement flow and weakening wall adhesion by increasing contact angle can enhance droplet detachment. However, the complex physical and chemical oil–wall interactions, a crucial reservoir feature, cannot be solely relied on the macroscopic representation through contact angle. A deviation in understanding the process of crude oil droplet detachment would be resulted due to the change of wall adhesion. Considering the intricate physical and chemical interactions between oil and walls, in this paper, we employed the extended Derjaguin–Landau–Verwey–Overbeek (EDLVO) theory to establish an oil–wall interaction forces system, and coupling computational fluid dynamics method to further explore the detachment dynamics of sessile oil droplets in a microchannel under varying EDLVO forces. The findings showed that (1) by increasing the Capillary number, the droplets gradually occur in four typical dynamic states: static, sliding, detachment, and pinch-off. (2) Static droplets are more prone to experience sliding behavior when influenced by EDLVO forces. (3) For droplets undergoing detachment and pinch-off, EDLVO forces inhibit entrainment behavior. These results contribute to an enhanced comprehension of droplet detachment dynamics in reservoirs, offering fresh insights for enhanced oil recovery strategies.
A modification of production term for the shear stress transport turbulence model based on a new wall-law for adverse pressure gradient
Authors: Shao Zhiyuan , Li Yifan , Song Hanqi , Ma Mingze , Yan Chao
Published: May 2024

This paper presents an attempt to improve the predictive accuracy of the Menter shear stress transport (SST) turbulence model for adverse pressure gradient (APG) flows. The foundation of this work lies in the newly modified law of the wall and turbulent kinetic energy (TKE) transport equation within the APG turbulent boundary layer. The modification of the law of the wall is achieved through a newly proposed variable λ, which is derived theoretically and calibrated using direct numerical simulation data. Based on the new law of the wall, we analyze the TKE transport equation of the SST model at APG and demonstrate that the analytical solution satisfying the law of the wall cannot achieve equilibrium in the current SST model. Further theoretical analysis reveals that this imbalance is caused by the TKE production term Pk, and the decomposition of the wall friction coefficient Cf indicates that Pk directly affects the prediction of flow separation. Based on the analysis and the new law of the wall, an additional term for Pk is suggested to correct Pk and improve the model's predictive accuracy for APG flows. Numerical validation results show that the correction leads to an increase in Pk within the APG turbulent boundary layer, resulting in more accurate predictions of Cf and the mean velocity profile in the inner layer of the turbulent boundary layer.
A novel multiphase and multicomponent model for simulating molecular diffusion in shale oil reservoirs with complex fracture networks
Authors: Han Yi , Lei Zhengdong , Wang Chao , Liu Yishan , Liu Jie , Du Pengfei , Wang Yanwei , Liu Pengcheng
Published: May 2024

Molecular diffusion is critical for enhanced oil recovery (EOR) in shale oil reservoirs with complex fracture networks. Understanding the influence of fractures on diffusive mass transfer is crucial for predicting oil recovery and remaining oil distribution. Diffusive mass transfer between fractures and matrix is critical in comprehensively and effectively simulating molecular diffusion. Resolution of matrix cells significantly affects diffusion accuracy at the fracture–matrix interface. Low resolution results in multiple fractures in the same matrix cell, leading to decreased precision in calculating mass transfer by conventional methods. To address this, a novel multiphase and multicomponent model is proposed. The new model integrating the consideration of fracture spacing modifies molecular diffusion transmissibility between fracture and matrix in an embedded discrete fracture model. The discretization employs the two-point flux approximation in the finite-volume method. Validation compares the coarser mesh to the finest grid as a reliable reference. Results show the proposed model accurately captures diffusive mass transfer in a coarser mesh. Modified models study molecular diffusion's effects on EOR in shale oil reservoirs with complex fracture networks by CO2 huff and puff. Results indicate that increasing injection rates cannot improve oil recovery under extremely low porosity and permeability. Molecular diffusion facilitates CO2 penetration into the formation. This expands the swept CO2 volume and increases both volume expansion and formation energy. In addition, the light and heavy components of the crude oil are diffused into the fractures and eventually produced, which reduces gas production in the case of diffusion.
Interaction between the helical vortices shed by contra-rotating propellers
Authors: Posa A. , Capone A. , Alves Pereira F. , Di Felice F. , Broglia R.
Published: May 2024

Large eddy simulation is adopted to analyze the interaction between the tip vortices shed by two contra-rotating propellers, by using a computational grid consisting of 4.6 × 109 points. Despite the complexity of the wake topology, the results of the computations show an excellent agreement with the measurements from an earlier experimental study on the same system. The interaction between the tip vortices shed by the two propellers produces vortex rings. Each of them consists of six helical sides, which are connected by U-shaped vortex lobes. The three upstream lobes of each vortex ring move to outer radial coordinates, as a result of their shear with the downstream lobes of the upstream vortex ring. In contrast, the downstream U-shaped lobes move to inner radial coordinates, as a result of their shear with the upstream lobes of the downstream vortex ring. This interaction results in an overall expansion of the wake of the contra-rotating propellers. The regions of shear between the U-shaped lobes of consecutive vortex rings are the areas of the largest turbulent stresses, which achieve higher levels than those produced in the wake of the two front and rear propellers working alone. This complex flow physics also triggers a faster instability of the wake system, breaking its coherence at more upstream coordinates, in comparison with the isolated propellers.
The multiferroic properties of Pb3Fe2F12
Authors: Xie Yi , Zhang Fan , Du Jun , Xu Qingyu
Published: May 2024

Fluoride ferroelectrics containing 3d transition metal ions are potential multiferroic candidates due to their ionic bonds rather than the covalent bonds in oxide ferroelectrics. In this work, Pb3Fe2F12 ceramics are prepared by solid-state reaction. Rietveld refinement of the x-ray diffraction pattern suggests that Pb3Fe2F12 adopts a crystalline structure similar to that of Pb5Fe3F19, containing FeF6 octahedra chains and isolated FeF6 octahedra. The deficiency of Pb content leads to the mixed valence states of Fe ions and strong distortion among the octahedra, thus, complicating exchange interactions between Fe ions. The antiferromagnetic transition temperature TN1 is observed at 160 K, which is significantly higher than that of stoichiometric Pb5Fe3F19. Various magnetic anomalies are observed at low temperatures due to the onset of different antiferromagnetic exchange interactions between Fe ions of different strengths with TN2 (∼45 K), TN3 (∼37 K), and TN4 (∼10 K). Weak ferromagnetism can be observed below TN2, and significant exchange bias is observed below TN4. Dielectric peaks, together with a magnetic field tunable pyroelectric current peak, are observed at around TN1, suggesting the multiferroic nature and magnetoelectric coupling in Pb3Fe2F12.
Impact of drops of epoxy resin and hardener, silicone and turpentine oils onto balsa wood and polypropylene substrates
Authors: Granda Rafael , Yurkiv Vitaliy , Mashayek Farzad , Yarin Alexander L.
Published: May 2024

Electrowetting and wettability-driven spreading of liquids on porous and nonporous substrates was investigated using impact of drops of epoxy resin, epoxy hardener, and epoxy resin and hardener, as well as silicone and turpentine oils with oil-soluble aniline dyes onto balsa wood and polypropylene surfaces. The experimental results revealed that the electric field stretched drops of epoxy resin, epoxy hardener, and epoxy resin and hardener after impact on polypropylene substrate in the long-term. The spreading of drops of epoxy resin and turpentine oil with dyes after impact onto porous balsa wood under the action of a 10 kV applied voltage was relatively weak. In addition, the measured footprint areas corresponding to drops of epoxy resin, epoxy hardener, and epoxy resin and hardener demonstrated a significant increase in the wetted areas driven by the applied voltage of 10 kV on polypropylene substrate, whereas on balsa wood, the footprint is practically unaffected by the electric field. Furthermore, it was determined that surface wettability was the main mechanism of spreading of epoxy resin, as well as silicone and turpentine oils with aniline dyes on porous balsa without the electric field applied. On the other hand, insufficient concentration of ions and counterions in silicone oil was responsible for the absence of electrohydrodynamic effects after impact of such drops onto porous balsa substrate subjected to high potentials of 7 and 10 kV. Hence, wettability-driven spreading with imbibition on balsa wood was the only reason for an increase in the wetted area in the case of silicone oil.
Translational motion of a spheroidal drop in a viscous fluid
Authors: Prakash Jai , Keh Huan J.
Published: May 2024

The problem of translational motion of a spheroidal drop along its axis of revolution in a viscous incompressible fluid is investigated semi-analytically. The flow fields in the exterior and interior of the drop are governed by the Stokes equations. Stream function formulation is adopted to solve the hydrodynamic equations in both regions. The general solution for the stream function in prolate and oblate spheroidal coordinates is expressed in an infinite-series form of semi-separation of variables. The leading order coefficients in the stream function are obtained using suitable boundary conditions. The hydrodynamic drag force experienced by the spheroidal drop is numerically evaluated with adequate convergence behavior for various values of the internal-to-external viscosity ratio and axial-to-radial aspect ratio of the drop. The numerical values of the drag force for the infinite and infinitesimal viscosity ratios agree with the available corresponding results for the slow translation of a slip spheroidal particle in the limiting conditions of no slip and full slip, respectively. At intermediate values of the viscosity ratio, the hydrodynamic force may not be a monotonic function of the aspect ratio. For a spheroidal drop with a fixed aspect ratio, its drag force increases monotonically with an increase in the viscosity ratio.
Theory of the momentum source method for synthetic turbulence
Authors: Shao Mingyu , Jiang Hanbo , Chen Shiyi
Published: May 2024

The interaction between turbulence and blade leading edges is known to have a significant impact on the aerodynamic and aeroacoustic performance of propellers. In addition to directly simulating turbulence, synthetic turbulence, such as the momentum source method, has been developed as a popular method for studying this interaction process in computational fluid dynamics and computational aeroacoustics. However, it is found that for non-periodic disturbances, although the induced velocity field is divergence-free, spurious noise may be generated in the source region and contaminate simulation results. To address this issue, the present work proposes adding a correction term so that the divergence-free condition is satisfied globally and the unwanted acoustic waves are suppressed, as an extension to our previous work for time-periodic gusts [H. Jiang, Phys. Fluids 35, 096115 (2023)]. The strength of the proposed approach lies in its simplicity, flexibility, and generality. First, it derives explicit source terms, which are straightforward for numerical implementations, to generate unsteady flow fluctuations. Second, the sources can be added inside the computational domain, saving computational costs for turbulence convection and being compatible with most existing boundary conditions. Third, the proposed method can obtain analytical expressions for the needed momentum source of the Navier–Stokes equation subject to any desired isotropic or anisotropic divergence-free turbulence fields. The method has been verified by examples of synthesizing harmonic gusts, Gaussian eddies, and random turbulence. The synthetic velocity results characterized by different spectral components are directly compared to target velocity fields, verifying the proposed approach and showing its capability. Parameters that influence the distribution of added sources are systematically investigated to identify an optimal combination for different scenarios. Finally, the model is employed to evaluate the aerodynamic interaction between an incoming turbulence and a thin airfoil. The obtained results exhibit good correspondence with analytical solutions.
Thermo-mechanical modeling of pancakelike domes on Venus
Authors: Calusi Benedetta , Farina Angiolo , Fusi Lorenzo , Rosso Fabio
Published: May 2024

In this paper, we present a mathematical model aimed at describing both the effusive and relaxing phase of pancakelike lava domes on the Venus surface. Our model moves from the recent paper by Quick et al. [“New approaches to inferences for steep-sided domes on Venus,” J. Volcanol. Geotherm. Res. 319, 93–105 (2016)] but generalizes it under several respects. Indeed, we consider a temperature field, playing a fundamental role in the flow evolution, whose dynamics is governed by the heat equation. In particular, we suggest that the main mechanism that drives cooling is radiation at the dome surface. We obtain a generalized form of the equation describing the dome shape, where the dependence of viscosity on temperature is taken into account. Still following Quick et al. [“New approaches to inferences for steep-sided domes on Venus,” J. Volcanol. Geothermal Res. 319, 93–105 (2016)], we distinguish an isothermal relaxing phase preceded by a non-isothermal (cooling) effusive phase, but the fluid mechanical model, developed in an axisymmetric thin-layer approximation, takes into account both shear thinning and thermal effects. In both cases (relaxing and effusive phase), we show the existence of self-similar solutions. In particular, this allows to obtain a likely scenario of the volumetric flow rate which originated this kind of domes. Indeed, the model predicts a time varying discharge, which is maximum at the beginning of the formation process and decreases until vanishing when the effusive phase is over. The model, in addition to fitting well the dome shape, suggests a possible forming scenario, which may help the largely debated questions about the emplacement and lava composition of these domes.
Measuring transaction costs of grassland eco-compensation policies: the case of the Compensation and Rewards Policy for Grassland Protection in Inner Mongolia Autonomous Region
Authors: Zhang Bao , Waldron Scott , Brown Colin , Zhang Jing , Qiao Guanghua
Published: May 2024

China is investing heavily in agri-environmental and eco-compensation schemes to address growing environmental problems in rural areas. However, assessments of the schemes often overlook transaction costs. Transaction costs are of particular importance in pastoral areas characterised by remoteness, dispersed populations, diverse agro-ecological conditions and heterogeneous livestock systems. Drawing on principles from institutional economics, this analysis investigated transaction costs associated with China’s current grassland eco-compensation schemes in Inner Mongolia and how they might change under alternative policy scenarios. The analysis examined the magnitude of overall transaction costs, their disaggregation among cost types and the incidence of the transaction costs at different administrative levels. The analysis found that the relative magnitude of transaction costs is substantial for the existing policy, whereas an alternative policy more effective in achieving stocking-rate reductions and improved grassland conditions increases transaction costs more than two-fold. The analysis demonstrated the value in accounting for transaction costs in the design and assessment of eco-compensation schemes.
Intertextual satire in media discourse
Authors: Doichyk Oksana , Yurchyshyn Vita , Velykoroda Yuriy
Published: May 2024

The paper investigates intertextual satire in media discourse from the cognitive linguistic perspective. Within
the frameworks of conceptual blending theory and the theory of precedent-related phenomena, we examine the cognitive processes of
producing and understanding intertextual satire. By modelling conceptual integration networks, we aim to specify the cognitive
mechanisms and operations involved in decoding intertextual satirical articles, drawing on examples from Private
Eye magazine. The study demonstrates that the basic cognitive mechanism involved in creating intertextual satire is
blending, and, in contrast to ironic utterances, which involve two contexts, in intertextual satire one and the same scenario
unfolds in three contexts: real, fictional, and satirical. Thus, the blend that occurs as a result of combining real and fictional
scenarios is verbalised and obvious to the recipient. The emergent structure, based on the blend, represents the intended
(non-verbalised) meaning of intertextual satire, namely indirect criticism of the real situation under focus.
Send it, receive it, quick erase it: A mouse model to decipher chemokine communication
Authors: Hermans Leen , O’Sullivan Timothy E.
Published: May 2024

A method to precisely determine which cells respond to chemokines in vivo is currently lacking. A novel class of dual fluorescence reporter mice could help identify cells that produce and/or sense a given chemokine in vitro and in vivo (Rodrigo et al. 2024. J. Exp. Med.https://doi.org/10.1084/jem.20231814).
Does spacetime have memories? Searching for gravitational-wave memory in the third LIGO-Virgo-KAGRA gravitational-wave transient catalogue
Authors: Cheung Shun Yin , Lasky Paul D , Thrane Eric
Published: May 2024

Gravitational-wave memory is a non-linear effect predicted by general relativity that remains undetected. We apply a Bayesian analysis framework to search for gravitational-wave memory using binary black hole mergers in LIGO-Virgo-KAGRA’s third gravitational-wave transient catalogue. We obtain a Bayes factor of

ln
⁡
BF
=

0.01

, in favour of the no-memory hypothesis, which implies that we are unable to measure memory with currently available data. This is consistent with previous work, suggesting that a catalogue of

O

(
2000
)

binary black hole mergers is needed to detect memory. We look for new physics by allowing the memory amplitude to deviate from the prediction of general relativity by a multiplicative factor A. We obtain an upper limit of A < 23 (95% credibility).
Low-temperature properties of magnetically frustrated rare-earth zirconates A
2Zr2O7
Authors: Vojtasová D , Staško D , Hájek F , Colman R H , Klicpera M
Published: May 2024

Rare-earth A
2Zr2O7 zirconates have attracted considerable attention of the scientific community for their complex magnetic, electronic and material properties applicable in modern technologies. The light rare-earth members of the series, crystallising in the pyrochlore variant of cubic crystal structure, have been studied in detail. The heavier A
2Zr2O7 compounds have been investigated mainly from the material properties viewpoint, focussing on their thermal properties and stability at high temperature and pressure. Low-temperature studies were mostly missing until recently. We present the low-temperature magnetic and thermodynamic properties of A
2Zr2O7 with A = Y, La, Nd, Eu, Gd, Tb, Dy, Ho, Tm, Yb, and Lu, well covering the whole series, newly synthesised by high-temperature sintering and melting methods. X-ray diffraction reveals and confirms the ordered pyrochlore structure in the light members, the disordered cubic structure of the defect-fluorite type in A
2Zr2O7 with A = Y, Gd–Yb, and finally the lower symmetry rhombohedral structure in the end-member Lu2Zr2O7. The specific heat of the investigated compounds is dominated by a low-temperature anomaly associated with magnetic ordering: long-range in light rare-earth zirconates; and short-range in heavier members. The effective magnetic moment in the studied compounds, determined by fitting the magnetisation data to the Curie–Weiss formula, is in good agreement with the expected value of the A
3+ free ion. The magnetic properties have been revealed to be strongly influenced by the geometric frustration of the magnetic moments of both the pyrochlore structure, as well as the face centred cubic lattice created by the cations of the defect-fluorite structure, but connected also to intrinsic atomic disorder. The experimental results are discussed in the framework of previous studies on A
2Zr2O7 zirconates, as well as other A
2
B
2O7 compounds.
Extraction of laser stripe centerlines from translucent optical components using a multi-scale attention deep neural network
Authors: Jiang Hao , Fu Weijie , Zhang Xinming , Zhang Chaoxia
Published: May 2024

The precise extraction of laser stripe centerlines is critical for line-laser 3D scanning systems. However, conventional methods relying on threshold segmentation and morphological operations face significant challenges when confronted with pervasive optical phenomena, including specular reflection, scattering, and bleeding, which are commonly observed in translucent optical components. These methods typically require complex preprocessing procedures and often yield poor precision in centerline extraction. In this paper, we introduce a novel learning-based approach, complemented by a meticulously curated dataset, explicitly designed to address these challenges. Our proposed method leverages a multi-scale attention U-Net-like architecture, initially tasked with the segmentation of laser stripes from the complex background environment. Subsequently, it employs the Steger algorithm for the precise extraction of laser stripe centerlines. The experimental results, obtained by comprehensively evaluating real-world captured images, clearly demonstrate the effectiveness of our deep neural network combined with the Steger algorithm. This combined approach exhibits exceptional accuracy even when challenged by the interferences from specular reflection, scattering, and bleeding artifacts. Specifically, our method achieves a mean intersection over union (mIoU) of 84.71% for the laser stripe detection task, accompanied by a mean square error (MSE) of 10.371 pixels. Also, the average execution time for the centerline extraction task is notably efficient at 0.125 s.
A fault diagnosis framework based on heterogeneous ensemble learning for air conditioning chiller with unbalanced samples
Authors: Jia Zhen , Yao Guoyu , Zhao Ke , Li Yang , Xu Peng , Liu Zhenbao
Published: May 2024

Big data-based air conditioning fault diagnosis research has developed rapidly in recent years, but in actual engineering, the fault sample size of air conditioning systems is much smaller than the normal sample size, and the resulting sample imbalance problem makes conventional data-driven diagnostic methods based on low accuracy and poor stability. In order to solve the problem of unbalanced fault diagnosis of air-conditioning chillers, this paper proposes an integrated learning-based diagnostic model, which achieves diagnosis by combining multiple base models and by majority voting. The method uses four classification models, namely, random forest model, decision tree model, k nearest neighbor model, and isomorphic integration model, as base classifiers, and synthesizes the four base classifiers into a heterogeneous integration algorithmic model (IMV) through integrated learning, and performs diagnostic detection of seven types of typical faults of chiller units using the majority voting method of integrated learning. The effectiveness of the proposed algorithm is verified on the RP-1043 dataset, and the experimental results show that the accuracy of the heterogeneous integrated algorithm model (IMV) can reach 96.87%, which is a significant improvement compared with the accuracy of the other four base classifier models (81.04%–96.25%). Therefore, the integrated learning model has some application prospects in fault diagnosis when targeting unbalanced datasets.
Proposal of a wireless sensor network for footstep localization and optimization of its location using bio-inspired metaheuristics
Authors: Sánchez-Márquez Luis , Reyes-Barranca Mario Alfredo , Abarca-Jiménez Griselda Stephany , López-Tapia Andrea , Flores-Nava Luis Martín
Published: May 2024

This paper introduces a proposal for a wireless network of smart sensors designed to capture the vibrations produced by the impact of a person’s footsteps on a dispersive and damped floor. These vibrations are utilized to pinpoint the location of impacts using a heuristic algorithm, enabling operation at a low data transmission/reception rate. Traditionally, the placement of sensors within a room has not been given significant consideration in the context of localization; however, our findings indicate that a detailed analysis of both the number and location of sensors can substantially enhance the accuracy of footstep localization. In this study, we have optimized the arrangement and quantity of sensors through the application of bio-inspired metaheuristics, aiming to minimize localization errors across the room. Upon evaluating various bio-inspired metaheuristic optimization algorithms, we identified the one that yielded the lowest estimation errors for the room as a whole. Our experimental tests demonstrate that such optimization significantly enhances the efficacy of the localization algorithm, resulting in a reduction of localization error ranging from 18.24% to 46.78% across different trajectories.
Unsupervised MRI motion artifact disentanglement: introducing MAUDGAN
Authors: Safari Mojtaba , Yang Xiaofeng , Chang Chih-Wei , Qiu Richard L J , Fatemi Ali , Archambault Louis
Published: May 2024

Objective. This study developed an unsupervised motion artifact reduction method for magnetic resonance imaging (MRI) images of patients with brain tumors. The proposed novel design uses multi-parametric multicenter contrast-enhanced T1W (ceT1W) and T2-FLAIR MRI images. Approach. The proposed framework included two generators, two discriminators, and two feature extractor networks. A 3-fold cross-validation was used to train and fine-tune the hyperparameters of the proposed model using 230 brain MRI images with tumors, which were then tested on 148 patients’ in-vivo datasets. An ablation was performed to evaluate the model’s compartments. Our model was compared with Pix2pix and CycleGAN. Six evaluation metrics were reported, including normalized mean squared error (NMSE), structural similarity index (SSIM), multi-scale-SSIM (MS-SSIM), peak signal-to-noise ratio (PSNR), visual information fidelity (VIF), and multi-scale gradient magnitude similarity deviation (MS-GMSD). Artifact reduction and consistency of tumor regions, image contrast, and sharpness were evaluated by three evaluators using Likert scales and compared with ANOVA and Tukey’s HSD tests. Main results. On average, our method outperforms comparative models to remove heavy motion artifacts with the lowest NMSE (18.34±5.07%) and MS-GMSD (0.07 ± 0.03) for heavy motion artifact level. Additionally, our method creates motion-free images with the highest SSIM (0.93 ± 0.04), PSNR (30.63 ± 4.96), and VIF (0.45 ± 0.05) values, along with comparable MS-SSIM (0.96 ± 0.31). Similarly, our method outperformed comparative models in removing in-vivo motion artifacts for different distortion levels except for MS- SSIM and VIF, which have comparable performance with CycleGAN. Moreover, our method had a consistent performance for different artifact levels. For the heavy level of motion artifacts, our method got the highest Likert scores of 2.82 ± 0.52, 1.88 ± 0.71, and 1.02 ± 0.14 (p-values

≪

0.0001) for our method, CycleGAN, and Pix2pix respectively. Similar trends were also found for other motion artifact levels. Significance. Our proposed unsupervised method was demonstrated to reduce motion artifacts from the ceT1W brain images under a multi-parametric framework.
Existence of a detachment cliff at ASDEX Upgrade
Authors: Scotti L , Cavedon M , Bernert M , Brida D , Kurzan B , Dux R ,   the ASDEX Upgrade Team
Published: May 2024

The detachment cliff is a bifurcative transition to partial detachment recently discovered at the DIII-D tokamak (McLean et al 2015 J. Nucl. Mater.
463 533–6). This work presents a database analysis of target parameters in L-mode and H-mode discharges to search for a detachment cliff at ASDEX Upgrade (AUG). Most of the transitions from attached to partially detached divertor conditions observed in H- and L-mode discharges in AUG show bifurcative-like characteristics that are consistent with the properties of the detachment cliff if the

B
×
∇
B

drift is directed towards the active X-point. In the operational space of power and density, the bifurcative transitions identified during an L-mode discharge occur at injected power and density higher than a threshold value (

P

tot

> 0.7  MW and n
e
> 1.6 × 10

19

m−3, respectively). Furthermore, the temperatures at which the transitions start are found to be insensitive to the injected impurity, the injected power and the value of the upstream density. Finally, the study of the evolution of the target parameters, of the intensity of the

D

α

line and of specific manometers and bolometer lines of sights shows that the physical process underlying the detachment cliff and the self-sustained divertor oscillations (Heinrich 2020 Nucl. Fusion
60 076013) might be the same.
Numerical simulations on loss of ICRF-heated NBI ions in EAST
Authors: Song Chengyi , Wang Ji , Wu Bin , Yin Lan , Gong Xueyu , Hao Baolong , Chen Yuqing , Huang Qianhong , Zhong Yijun , Xie Yahong , Xie Yuanlai
Published: May 2024

The loss of ion cyclotron resonance frequencies (ICRF)-heated neutral beam injection ions in experimental advanced superconducting tokamak was numerically investigated by ORBIT code simulations. The effects of collisions and ripples on particle losses were taken into account, and the distributions of fast ions generated by different beams in combination with ICRF heating were calculated using the TRANSP code. Results showed that ICRF waves altered the orbital distributions of beam ions, causing an increase in trapped ions and fast ion losses. Additionally, for co-current injected beams, perpendicular injection resulted in higher fast ion losses in synergistic heating than tangential injection. The study also found that the synergistic effect of collisions and ripples enhanced fast ion losses, which were highly localized and generated a maximum heat load of 0.165 MW m−2 on the first wall. However, conducting synergy heating experiments at high plasma currents and low effective ion charge numbers can significantly reduce the loss of fast ions.
Isolated attosecond electron and hard x-ray pulse generation by ultra-intense spatiotemporal vortex laser
Authors: Ju L B , Wu C N , Yu M Y , Huang T W , Zhang H , Wu S Z , Zhou C T , Ruan S C
Published: May 2024

The spatiotemporal optical vortex (STOV) laser pulse, characterized by containing a space-time dependent spiral phase structure and intrinsic transverse orbital angular momentum (OAM), has been of much recent research interest for basic physics as well as potential applications in optical communication and manipulation, as well as the attosecond sciences. Here we consider electron acceleration and generation of attosecond hard x-rays by irradiating a thin foil with intense STOV laser pulse. It is found that the affected foil electrons can be trapped and acquire transverse OAM, or synchrotron-like motion, from the STOV, as well as accelerated forward by the transverse and enhanced axial laser electric fields to form a tiny energetic bunch at the front of the laser pulse and emit short (

∼

400

attosecond) high-flux (

>

10

9

photons per pulse) hard (100–1000 keV) x rays.