bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiphase holdup measurement of oil–gas–water flow using new dual receiver fiber-optical probe array multiphase logging tool
Authors: Hao Hu , Kong Deming , Chen Xiaoyu , Wu Peiliang , Zhao Fengda , Kong Dehan , Chen Jiliang , Liu Guoquan , Kong Lingfu
Published: February 2023

To solve the problem of multiphase holdup measurement, a new dual-receiver fiber-optical probe array multiphase logging tool (NDRFOPA_MLT) is designed and developed. This paper first constructed the mechanism model of an NDRFOP for phase holdup measurement by using the ray tracing method and theoretically analyzed the feasibility of NDRFOP to measure phase holdup; considering the shortcomings of NDRFOP local measurement, a NDRFOPA sensor for oil production three-phase flow is designed and developed. At the same time, the volume of fluid model was used to simulate the distribution characteristics of the medium in the NDRFOPA_MLT measurement pipeline under the working conditions of oil–gas–water flow with a total flow rate range of 0.42–1.25 m3/h, water holdup range of 50%–80%, oil holdup range of 10%–30%, and gas holdup range of 10%–40%. In addition, the NDRFOPA_MLT measurement models for different multiphase flow conditions were established by the ZEMAX ray tracing method, and the sensitivity distribution, response characteristics, and phase holdup measurement methods were studied to obtain the phase holdup measurement results under multiphase flow conditions. Finally, a multiphase flow experimental platform with a measurement pipe diameter of 20 mm and a measurement pipe length of 300 mm was established, and experiments were conducted under multiphase flow conditions, such as a gas flow rate range of 0.04–0.16 m3/h, oil flow rate range of 0.64–1.70 m3/h, and water flow rate range of 0.53–2.58 m3/h. The experimental results showed that phase holdup measurement error was mainly kept within 10%.
Microscopic theory of adsorption kinetics
Authors: Scher Yuval , Lauber Bonomo Ofek , Pal Arnab , Reuveni Shlomi
Published: February 2023

Adsorption is the accumulation of a solute at an interface that is formed between a solution and an additional gas, liquid, or solid phase. The macroscopic theory of adsorption dates back more than a century and is now well-established. Yet, despite recent advancements, a detailed and self-contained theory of single-particle adsorption is still lacking. Here, we bridge this gap by developing a microscopic theory of adsorption kinetics, from which the macroscopic properties follow directly. One of our central achievements is the derivation of the microscopic version of the seminal Ward–Tordai relation, which connects the surface and subsurface adsorbate concentrations via a universal equation that holds for arbitrary adsorption dynamics. Furthermore, we present a microscopic interpretation of the Ward–Tordai relation that, in turn, allows us to generalize it to arbitrary dimension, geometry, and initial conditions. The power of our approach is showcased on a set of hitherto unsolved adsorption problems to which we present exact analytical solutions. The framework developed herein sheds fresh light on the fundamentals of adsorption kinetics, which opens new research avenues in surface science with applications to artificial and biological sensing and to the design of nano-scale devices.
High resolution spatially extended 1D laser scattering diagnostics using volume Bragg grating notch filters
Authors: Bak J. , Suazo Betancourt J. L. , Rekhy A. , Abbasszadehrad A. , Miles R. B. , Limbach C. M. , Walker M. L. R.
Published: February 2023

Laser light scattering systems with volume Bragg grating (VBG) filters, which act as spectral/angular filters, have often been used as a point measurement technique, with spatial resolution as low as a few hundred μm, defined by the beam waist. In this work, we demonstrate how VBG filters can be leveraged for spatially resolved measurements with several μm resolution over a few millimeters along the beam propagation axis. The rejection ring, as determined by the angular acceptance criteria of the filter, is derived analytically, and the use of the ring for 1D laser line rejection is explained. For the example cases presented,i.e., for a focused probe beam waist with a diameter of ∼150 μm, the rejection ring can provide resolution up to several millimeter length along the beam propagation axis for a 1D measurement, which is also tunable. Additionally, methods to further extend the measurable region are proposed and demonstrated, using a collimation lens with a different focal length or using multiple VBG filters. The latter case can minimize the scattering signal loss, without the tradeoff of the solid angle. Such use of multiple VBGs is to extend the measurable region along the beam axis, which differs from the commonly known application of multiple filters, to improve the suppression of elastic interferences. 1D rotational Raman and Thomson scattering measurements are carried out on pulsed and DC discharges to verify this method. The system features compactness, simple implementation, high throughput, and flexibility, to accommodate various experimental conditions.
Uniqueness and absence of percolation of classical gases
Authors: Poghosyan Suren , Zessin Hans
Published: February 2023

We reconsider Mürmann’s theorem, i.e., the 1-1 correspondence between Poisson exclusion finite-cluster processes and subcritical stable Gibbs processes of finite range. Subcritical processes realize configurations that decompose into only finite clusters. Existence or uniqueness of Poisson exclusion cluster processes then imply the corresponding statement for subcritical, stable Gibbs processes of finite range. Applications to continuum Potts models are given.
A spectral MUSCL scheme for gPC-Galerkin method to uncertain hyperbolic equations
Authors: Li Linying , Zhang Bin , Liu Hong
Published: February 2023

This paper deals with a problem that we found when directly implementing the scalar MUSCL scheme to spectral coefficient equations of the gPC-Galerkin method. The order degradation at extrema of spectral coefficients and non-uniform reconstruction process lead to a distortion of standard deviation at some extrema, especially where the peak consists of several extrema of coefficients. From the perspective of probability space, a spectral MUSCL scheme is proposed based on the generalized minmod limiter to avoid the defects mentioned above when applying the scalar MUSCL. In this paper, we present some properties of the new scheme related to total variation and demonstrate them by the uncertain linear scalar conservation law. Finally, we employ this scheme to compressible Euler equations, and a good correlation of standard deviation is obtained. The details of implementation of the gPC-Galerkin method for Euler equations are also discussed, and the approximate Jacobian matrix is adopted.
The low-cyclic fatigue response and its dependence of specific surface area for open-cell nanoporous Cu
Authors: Bi W. B. , Wang Y. F. , Zhang X. M. , Deng L. , Tang J. F. , Zhao F. , Wang L.
Published: February 2023

We systematically study the low cycle fatigue behavior and its dependence of specific surface area (ζ) for nanoporous copper (NPC) under ultrahigh strain rate (γ˙≈109 s−1) cyclic shear loading by conducting large-scale molecular dynamic simulation and small-angle x-ray scattering analysis. With an increase in ζ, NPC undergoes a transition from the first excellent anti-fatigue property (ζ<1.24nm−1) to the subsequent easy-to-fatigue capacity (ζ≥1.24nm−1). Two different mechanisms are governing fatigue: (i) smooth nucleation and propagation of dislocations for the former and (ii) nanopore compaction/coalescence for the latter by prohibiting the activities of dislocations. For NPC with ζ=0.42nm−1, fatigue contributes to a surprising superelasticity, prompted by the entanglements and reversed disentanglements of longer dislocations. Surface reconstruction contributes to the fatigue tolerance of NPC by facilitating local surface roughening and the emission of dislocation slips, and it becomes more pronounced with decreasing ζ.
Can wind turbine farms increase settlement of particulate matters during dust events?
Authors: Mataji Mohammadreza , Ashrafi Khosro , Shafie Pour-Motlagh Majid
Published: February 2023

Dust event is one of the main environmental problems affecting several countries of the world, and the dust burden is a severe threat to human health, environment, and socio-economic activities. Nevertheless, controlling windblown dust is a major challenge that hitherto has not been effectively overcome. Wind turbines can extract a considerable amount of kinetic energy from wind, reduce wind speed, and increase turbulence in the following wake, but can wind turbine farms increase the settlement of particulate matter during dust events? To examine this question, this study develops a framework based on FLOw Redirection and Induction in Steady State that calculates essential parts of the flow and dust concentration fields in wind farms. Eight different layouts and three wind turbines have been simulated to find the best wind farm arrangement that yields maximum dust deposition. It is found that wind farms, depending on the layout, decrease the wind speed by 8%–14.5%. In the best scenario, wind farms increase PM2.5 deposition by 23.3% and PM10 deposition by 34.2% compared to no wind farm case. Therefore, this study suggests that using wind turbine farms as wind barriers, provided the surface itself is not erodible, can be an effective way to control windblown dust.
Cavity-enhanced zero-phonon emission from an ensemble of G centers in a silicon-on-insulator microring
Authors: Lefaucher B. , Jager J.-B. , Calvo V. , Durand A. , Baron Y. , Cache F. , Jacques V. , Robert-Philip I. , Cassabois G. , Herzig T. , Meijer J. , Pezzagna S. , Khoury M. , Abbarchi M. , Dréau A. , Gérard J.-M.
Published: February 2023

We report the incorporation of an ensemble of G centers in silicon-on-insulator (SOI) microrings using ion implantation and conventional nanofabrication. The coupling between the emitters and the resonant modes of the microrings is studied using continuous-wave and time-resolved microphotoluminescence (PL) experiments. We observe the resonant modes of the microrings on PL spectra, on the wide spectral range that is covered by G center emission. By finely tuning the size of the microrings, we match their zero-phonon line at 1278 nm with a resonant mode of quality factor around 3000 and volume 7.2 (λ/n)3. The zero-phonon line intensity is enhanced by a factor of 5, both in continuous-wave and time-resolved measurements. This is attributed to the Purcell enhancement of zero-phonon spontaneous emission into the resonant mode and quantitatively understood considering the distribution of the G center dipoles. Despite the enhancement of the zero-phonon emission, we do not observe any sizeable decrease in the average lifetime of the G centers, which points at a low radiative yield (<10%). We reveal the detrimental impact of parasitic defects in heavily implanted silicon and discuss the perspectives for quantum electrodynamics experiments with individual color centers in lightly implanted SOI rings. Our results provide key information for the development of deterministic single-photon sources for integrated quantum photonics.
Simulation of heavy ion irradiation effect on 3D MOSFET
Authors: Li Ke , Hao Jianhong , Zhao Qiang , Zhang Fang , Dong Zhiwei
Published: February 2023

Single event upset effect is an important factor that causes performance degradation and functional failure of aerospace equipment components in space radiation environment. When high-energy particles incident on semiconductor devices in working state, they will induce functional errors of devices and even cause permanent damage. Based on the finite element method, the three-dimensional simulation of Metal-oxide-semiconductor field-effect transistor (MOSFET) is carried out. The single event upset effect of MOSFET under heavy ion irradiation and the influence of heavy ion irradiation on transient drain current are investigated. The results show that the transient drain current of MOSFET devices will increase rapidly when heavy ions are incident, and then the logic state of the devices will change. With the increase in linear energy transfer density, the peak value of the transient drain current pulse increases and the pulse width decreases. With the increase in the incident angle, the peak value of the pulse first increases and then decreases. The maximum value is obtained when the incident angle is vertical, the pulse width first decreases and then increases, and the minimum value is obtained when the incident angle is vertical. With the increase in MOSFET size, the difference of transient drain current formed by symmetrical heavy ion incidence is becoming smaller and smaller. When the incident track is completely in the drain region, the simulation results are the same.
Impact of photoexcitation on secondary electron emission: A Monte Carlo study
Authors: Ouyang Wenkai , Zuo Xiangying , Liao Bolin
Published: February 2023

Understanding the transport of photogenerated charge carriers in semiconductors is crucial for applications in photovoltaics, optoelectronics, and photo-detectors. While recent experimental studies using scanning ultrafast electron microscopy (SUEM) have demonstrated that the local change in the secondary electron emission induced by photoexcitation enables direct visualization of the photocarrier dynamics in space and time, the origin of the corresponding image contrast still remains unclear. Here, we investigate the impact of photoexcitation on secondary electron emissions from semiconductors using a Monte Carlo simulation aided by time-dependent density functional theory. Particularly, we examine two photoinduced effects: the generation of photocarriers in the sample bulk and the surface photovoltage (SPV) effect. Using doped silicon as a model system and focusing on primary electron energies below 1 keV, we found that both the hot photocarrier effect immediately after photoexcitation and the SPV effect play dominant roles in changing the secondary electron yield (SEY), while the distribution of photocarriers in the bulk leads to a negligible change in SEY. Our work provides insights into electron–matter interaction under photo-illumination and paves the way toward a quantitative interpretation of the SUEM contrasts.
Single-shot wide-field imaging in reflection by using a single multimode fiber
Authors: Liu Yifan , Yu Panpan , Wu Yijing , Wang Ziqiang , Li Yinmei , Liang Jinyang , Lai Puxiang , Gong Lei
Published: February 2023

A single multimode fiber (MMF) provides almost an ideal optical channel to constitute a hair-thin endoscope for minimally invasive biomedical imaging at depths in tissue, especially if the imaging operation can be performed with one single shot in reflection mode, which, however, remains challenging to date. In this work, we present single-shot wide-field reflectance imaging by using a single MMF as the illumination unit and imaging probe simultaneously. To achieve single-shot image capture, a reflection matrix of the fiber was built by a learning-assisted approach for the universal inverse conversion from the output amplitudes to the input amplitudes. The performance was tested by imaging more than 30 000 natural scenes projected by a digital micromirror device, and an averaged Pearson correlation coefficient over 0.84 with respect to the ground truth was achieved in the experiment. Furthermore, the ability to image dynamic scenes at a high frame rate of up to 180 frames per second was demonstrated together with real-time observation of a freely moving microneedle located at the distal end of the MMF. The proposed reflection-mode single-fiber imaging scheme paves the way for practical video-rate microendoscopy at depths in tissue in a minimally invasive manner.
Temporal evolution of flow field structure for vehicles accelerating in evacuated tube transportation system
Authors: Zhong Sha , Yang Mingzhi , Qian Bosen , Wang Tiantian , Wu Fan , Zhang Lei
Published: February 2023

As a supersonic transportation system, the flow around a vehicle in an Evacuated Tube Transportation (ETT) system will evolve through series of flow structures during acceleration. The occurrence of choked flow and shock wave will especially lead to the drastic change in flow field structures. In this study, based on the one-dimensional inviscid flow assumption, a theoretical model is established to quantitatively describe the formation time, formation location of choked flow, and Frontal Normal Shock Wave (FNSW), as well as the distance of the disturbed flow field region ahead of the vehicle in the ETT system. It is found out that the formation time of FNSW as well as the initial distance between the vehicle head and FNSW is linearly proportional to the blockage ratio while linearly inverse proportional to the acceleration rate of the vehicle. An experimentally verified numerical model is also established with an overset mesh technique to investigate the flow field evolution for vehicles accelerating in the ETT system. The results from numerical analysis agree well with the theoretical model. Meanwhile, five typical flow field structures are summarized for a vehicle accelerating from a stationary state to supersonic state in the ETT system. The applicability of the wind tunnel method and overset mesh technique in numerical simulation of the ETT system is systematically discussed. The influence of occurrence and dissipation of choked flow and shock wave on the vehicle's aerodynamic drag profile are then analyzed quantitatively.
Oscillatory exchange bias controlled by RKKY in magnetic multilayers
Authors: Polishchuk D. M. , Persson M. , Kulyk M. M. , Baglioni G. , Ivanov B. A. , Korenivski V.
Published: February 2023

Ferromagnetic/antiferromagnetic bilayers are interfaced with normal metal/ferromagnetic bilayers to form F*/AF/N/F valves. The N-spacer thickness is chosen such that it mediates strong indirect exchange [Ruderman–Kittel–Kasuya–Yosida (RKKY)] between the outer ferromagnetic layers, which varies in strength/direction depending on the N thickness and changes its direction on switching F. The system exhibits a strong modulation of the F*/AF exchange bias, oscillating in strength synchronously with the oscillation in the interlayer RKKY exchange across the normal metal spacer. The effect is explained as due to a superposition taking place within the antiferromagnetic layer of the direct-exchange proximity effect from the F*/AF interface and the indirect RKKY exchange from F penetrating AF via N. The modulation, expressed via the strength of the F*/AF bias field, reaches 400% at the first RKKY peak.
Planar AlN/GaN resonant tunneling diodes fabricated using nitrogen ion implantation
Authors: Zhang Baoqing , Yang Liuyun , Wang Ding , Cheng Kai , Sheng Bowen , Liang Zhiwen , Yuan Ye , Shen Bo , Wang Xinqiang
Published: February 2023

We report planar AlN/GaN resonant tunneling diodes (RTDs) fabricated using a nitrogen ion implantation isolation process on silicon substrates. The active area of AlN/GaN RTDs is defined by nitrogen ion implantation. A planar RTD consists of two different-sized RTDs connected in series, where the larger one acts as a resistor and the performance of the planar RTD is determined by the smaller one. Repeatable and hysteresis-free negative differential resistances without degradation are observed through 500 continuous bidirectional voltage sweeps. The peak current density is 15.5 kA/cm2. The RTD exhibits stable negative differential resistance (NDR), with the peak-to-valley current ratio varying from 1.39 to 1.28 as the temperature increases from 77 to 295 K. This practicable and reproducible ion implantation process is compatible with silicon fabrication technology. It, thus, provides a feasible method for device design of GaN-based RTDs and facilitates the implementation of complex monolithic microwave integrated circuits based on planar III-nitride RTDs on large-size silicon wafers.
Exchange stiffness constant determination using multiple-mode FMR perpendicular standing spin waves
Authors: Waring H. J. , Li Y. , Johansson N. A. B. , Moutafis C. , Vera-Marun I. J. , Thomson T.
Published: February 2023

The exchange stiffness constant is recognized as one of the fundamental properties of magnetic materials, though its accurate experimental determination remains a particular challenge. In thin films, resonance measurements exploiting perpendicular standing spin waves (PSSWs) are increasingly used to extract this parameter, typically through a determination of the first-order PSSW mode. Here, we present a systematic study of multiple PSSW modes in NiFe films, where both the sample thickness and the cap layer material are varied. The results show that a simple analysis based on the Kittel rigid pinning model yields an exchange stiffness constant that varies with thickness, mode number, and capping layer material. This finding is clearly inconsistent with physical expectation that the exchange stiffness constant of a material is single valued for a particular set of thermodynamic conditions. Using a more general exchange boundary condition, we show, through a comprehensive set of micromagnetic simulations, that a dynamic pinning mechanism originally proposed by Wigen is able to reproduce the experimental results using a single value of Aex. Our findings support the utility of short wavelength, higher order PSSWs to determine the Aex of thin films and show that the value of Aex obtained has a weak dependency on the material immediately adjacent to the magnetic layer.
Amplitude modulation of velocity fluctuations in the atmospheric flows over real urban morphology
Authors: Liu Yixun , Liu Chun-Ho , Brasseur Guy P. , Chao Christopher Y. H.
Published: February 2023

Amplitude modulation (AM) quantifies the top-down interactions between the large-scale motions (LSMs) in the outer layer and the near-ground turbulence structures. They are important to the momentum transport and pollutant dispersion in urban atmospheric surface layers (ASLs). The dataset of large-eddy simulation over a densely built region in Kowloon Peninsula, Hong Kong, therefore, is adopted to investigate the AM of small-scale eddies by LSMs in the ASL over real urban morphology. Alike its smooth-wall counterpart, the small-scale eddies are (positively) amplitude modulated by the LSMs in most regions of the roughness sublayer (RSL). However, negative AM is unexpectedly found in the RSL on the building windward side in this study, illustrating the heterogeneity of the urban surface and the flow dynamics being affected aloft. In addition, strong sweep (u′ > 0 and w′ < 0) and ejection (u′ < 0 and w′ > 0) dominate the flows, respectively, in the positive and negative AM zones. In the positive AM zones, the large-scale sweep (uL′ > 0) leads to the surplus in the small-scale turbulence kinetic energy (TKE), while the large-scale ejection (uL′ < 0) brings a TKE deficit to the small-scale eddies. By contrast, the large-scale sweeps result in a TKE deficit to the small-scale eddies and the large-scale ejections result in a TKE surplus in the negative AM zones. These findings could help elucidate the AM over different building designs and urban morphology in cities, promoting the momentum transport and pollutant dispersion via proper city planning.
Tunable bilayer photonic quasicrystal
Authors: Vovk Ilia A. , Rukhlenko Ivan D. , Baimuratov Anvar S.
Published: February 2023

The unique properties of incommensurate two-dimensional bilayer structures, a wide class of optical materials, are largely determined by the relative rotation angle between the layers. Here, we present a comprehensive theoretical analysis of the optical properties of a dodecagonal quasicrystal based on twisted bilayer material with hexagonal layers rotated by 30°. By assuming that the quasicrystal is tuned to the Bragg condition, we calculate its reflectance spectra and reveal the Wood anomalies therein, which are characteristics of structures with a long-range order. It is also shown that the reflectance spectra can be dynamically controlled by the external electric field applied perpendicular to the quasicrystal's surface. This feature can be used to create tunable photonic devices such as optical switches and sharp M-shape bandpass filters.
Hydrodynamic instability of odd-viscosity-induced shear-imposed falling film
Authors: Paul Dipankar , Hossain Md. Mouzakkir , Behera Harekrushna
Published: February 2023

In this paper, an analysis of linear and weakly nonlinear stability for an odd-viscosity-induced shear-imposed falling film over an inclined plane is performed. Using the Chebyshev spectral collocation approach, the linear effect for disturbance of arbitrary wavenumbers is numerically examined by solving the Orr–Sommerfeld eigenvalue problem within the framework of normal mode analysis. The study reveals that instability rises with increasing external shear in the streamwise direction. However, as external shear rises in the reverse flow direction, wave energy is dissipated, and the surface wave stabilizes. Furthermore, the longwave expansion method is applied to calculate the nonlinear surface deformation expression, and it is found that the odd viscosity has the ability to stabilize the fluid flow instability caused by a positive shear force. The investigation of weakly nonlinear stability is also performed using the multiple scale method, which led to the Ginzburg–Landau equation of the nonlinear surface deformation equation. The corresponding results confirm the significant effect of both imposed shear and odd viscosity coefficient on the existent subcritical unstable and supercritical stable zones along with unconditional and explosive zones near the threshold of the film flow instability. The bandwidth of the subcritical stable zone mitigates for the higher viscosity ratio while it enhances the flow-directed potent imposed shear. Additionally, the amplitude and phase speed of nonlinear waves in the supercritical stable regime rise with increasing induced shear in the fluid flow direction and gradually decrease with increasing the value of the odd viscosity coefficient.
Isotropic scattering with a rigid upper surface at the onset of phototactic bioconvection
Authors: Kumar Sandeep
Published: February 2023

In this article, we investigate a phototactic bioconvection model that includes both absorption and isotropic scattering in the suspension with the top and bottom boundaries assumed to be rigid. To solve the steady-state boundary value problem, a shooting method is used. Through the use of this model, a linear stability analysis is examined. Newton–Raphson–Kantorovich method of fourth order is used to investigate the linear stability of the system. The critical wavenumber is zero for vanishing scattering albedo and becomes non-zero as scattering albedo is increased. The system is more stable for the rigid upper surface than the stress-free upper surface.
Force balance model for spontaneous droplet motion on bio-inspired topographical surface tension gradients
Authors: Misiiuk Kirill , Blaikie Richard , Sommers Andrew , Lowrey Sam
Published: February 2023

Passive gradient-driven droplet motion has been demonstrated in nature, inspiring coating-free surface tension gradient surfaces that can be fabricated via laser ablation. These surfaces can potentially enhance heat exchanger performance, promoting drop-wise over film-wise condensation, and be suitable for lab-on-a-chip applications, allowing the directional transport of microliter size droplets. In this work, a theoretical model and its application to variable-pitch hierarchical superhydrophobic gradients are discussed, and the method is experimentally validated against various gradient topographical designs. The proposed force balance model allows analysis of the impact of the topography on the forces acting on the droplet. The discrepancy between modeled and observed contact angles in most cases does not exceed 10%. The modeled droplet footprint fits the experimentally measured ones with an error of less than 10% for most cases. Though modeled motion distances were twice greater than experimentally observed ones, the comparison of the proposed model with the originally developed theory showed that the difference in the net force was less than 5%. Both observed and average velocities were within less than 30% difference. Like the traditional models, the new model overestimates droplet kinematics; however, it does not require knowledge a priori of all the contact angles across the gradient during droplet motion, relying only on the material's surface tension and the local surface area fraction. Therefore, the model presents a simplified and convenient means of designing a linear topographical gradient for spontaneous droplet motion.
Improving the collection efficiency in the hot carrier tunneling device by optimizing the thickness of tunneling barrier for balancing the acceleration and scattering processes
Authors: Song Guichen , Chen Yicong , Deng Shaozhi , Chen Jun
Published: February 2023

Improving the collection efficiency is one of the major challenges in fabricating high performance gated hot carrier tunneling devices that have important applications in electronics and optoelectronics. In this work, a general model for a gated hot carrier tunneling device has been established to figure out the optimized thickness of a tunneling barrier for maximizing the collection efficiency. Simulation indicates that the maximum efficiency increases with the field F, the tunneling barrier height Φ0, and the mean free path λ but decreases with the threshold energy Et. In addition, the optimal thickness of the tunneling barrier decreases as F and Φ0 increase or λ and Et decrease, which varies from ∼6 to ∼9 nm depending on the above-mentioned parameters. To verify the model, electron emission characteristics of a few layers graphene (FLG)/h-BN/FLG heterostructure with different thickness of h-BN have been measured. A similar dependence of the averaged emission efficiency on the h-BN thickness has been obtained, which can be fitted by an extended model for the case of FLG/h-BN/FLG with consideration of a hot hole-induced Auger process. All the results are useful for designing a high performance hot carrier tunneling device.
Comparison of flow characteristics behind squareback bluff-bodies with and without wheels
Authors: Su Xinchao , He Kan , Xu Kewei , Gao Guangjun , Krajnović Siniša
Published: February 2023

The wake dynamics of two referenced variations of the squareback Windsor model with and without wheels is numerically studied by performing improved delayed detached eddy simulation. Numerical assessments are validated against publicly available experimental data. The focus of this study is on the wake states influenced by the wheels and the thick oncoming floor boundary layer. Results show that the addition of the wheels significantly changes the aerodynamic forces, the underbody flow, and the wake topology. The wake bi-stability is also enhanced with wheels in place due to the increased curvature of lateral shear layers in the near wake. However, the bi-stable behavior is largely suppressed when immersed in a thick boundary layer. These alterations depend on the degree of interaction between the wake recirculation and the bottom flow, and such degree is strongly affected by the underbody flow momentum. The evolution of low-order flow organizations and complementary spectral analysis highlight the differences in the coherent dynamics of the wake. The finding of this present work suggests that the wake bi-stability behind the squareback body can exist not only for a simplified geometry but also for a more realistic car with wheels in real-world upstream conditions.
Melting conditions and entropies of superionic water ice: Free-energy calculations based on hybrid solid/liquid reference systems
Authors: Fidalgo Cândido Vitor , Matusalem Filipe , de Koning Maurice
Published: February 2023

Superionic (SI) water ices—high-temperature, high-pressure phases of water in which oxygen ions occupy a regular crystal lattice whereas the protons flow in a liquid-like manner—have attracted a growing amount of attention over the past few years, in particular due to their possible role in the magnetic anomalies of the ice giants Neptune and Uranus. In this paper, we consider the calculation of the free energies of such phases, exploring hybrid reference systems consisting of a combination of an Einstein solid for the oxygen ions occupying a crystal lattice and a Uhlenbeck-Ford potential for the protonic fluid that avoids irregularities associated with possible particle overlaps. Applying this approach to a recent neural-network potential-energy landscape for SI water ice, we compute Gibbs free energies as a function of temperature for the SI fcc and liquid phases to determine the melting temperature Tm at 340 GPa. The results are consistent with previous estimates and indicate that the entropy difference between both phases is comparatively small, in particular due to the large amplitude of vibration of the oxygen ions in the fcc phase at the melting temperature.
Machine learning enables robust prediction of thermal boundary conductance of 2D substrate interfaces
Authors: Foss Cameron , Aksamija Zlatan
Published: February 2023

Two-dimensional van der Waals (vdW) materials exhibit a broad palette of unique and superlative properties, including high electrical and thermal conductivities, paired with the ability to exfoliate or grow and transfer single layers onto a variety of substrates thanks to the relatively weak vdW interlayer bonding. However, the same vdW bonds also lead to relatively low thermal boundary conductance (TBC) between the 2D layer and its 3D substrate, which is the main pathway for heat removal and thermal management in devices, leading to a potential thermal bottleneck and dissipation-driven performance degradation. Here, we use first-principles phonon dispersion with our 2D–3D Boltzmann phonon transport model to compute the TBC of 156 unique 2D/3D interface pairs, many of which are not available in the literature. We then employ machine learning to develop streamlined predictive models, of which a neural network and a Gaussian process display the highest predictive accuracy (RMSE < 5 MW m−2 K−1 and R2> 0.99) on the complete descriptor set. Then we perform sensitivity analysis to identify the most impactful descriptors, consisting of the vdW spring coupling constant, 2D thermal conductivity, ZA phonon bandwidth, the ZA phonon resonance gap, and the frequency of the first van Hove singularity or Boson peak. On that reduced set, we find that a decision-tree algorithm can make accurate predictions (RMSE < 20 MW m−2 K−1 and R2> 0.9) on materials it has not been trained on by performing a transferability analysis. Our model allows optimal selection of 2D-substrate pairings to maximize heat transfer and will improve thermal management in future 2D nanoelectronics.
Relationship of pig carcass grade with the amount of pork belly estimated with AutoFom III
Authors: Ko Eunyoug , Park Yunhwan , Park Kwangwook , Woo Changhyun , Park Sanghun , Kim Yun-a , Park Gyutae , Oh Sehyuk , Kim Jaeyoung , Choi Jungseok
Published: February 2023

Context Pork belly is the most preferable and expensive primal cut among various primal cuts in Korea. Aim The aim of this study was to investigate the relationship of pig carcass grade with the amount of pork belly (kg). Methods In total, 350 179 Landrace, Yorkshire, and Duroc (LYD) pigs were graded with the Korean Pig Carcass Grade System. Amount of pork belly cut was estimated with an AutoFom III equipment. Key results Distribution characteristics of carcass weight, backfat thickness, belly weight, and belly fat percentage were analysed. When the yield of pork belly was investigated by grade, lower-grade carcass had a higher amount of pork belly (P < 0.0001). The correlation coefficients between carcass weight and belly weight were 0.798 for Grade 1+, 0.906 for Grade 1, and 0.932 for Grade 2 (P < 0.0001). The correlation between backfat thickness and belly weight was lower with a decreasing grade. Regression analysis was performed with carcass weight or backfat thickness as a dependent variable and belly weight as an independent variable. Coefficients of determination (ρ2) of carcass weight and belly weight for each grade were higher for a lower grade (0.637 for Grade 1+, 0.821 for Grade 1, 0.867 for Grade 2). Conclusion The lower-grade pork belly, the most expensive in Korea, had a higher quantity of pork belly, and the correlation coefficient between pork belly and carcass weight and between pork belly and backfat thickness was higher as the lower grade level increased. Implication For a reasonable price of pork in the market, the current lean meat-based carcass-grading system should also include the yield of each primal cut.
Increasing the accuracy and efficiency of wildlife census with unmanned aerial vehicles: a simulation study
Authors: Fust Pascal , Loos Jacqueline
Published: February 2023

Context Manned aerial surveys are an expensive endeavour, which is one of the core reasons for insufficient data coverage on wildlife monitoring in many regions. Unmanned aerial vehicles (UAVs) can be a valid, cost-efficient alternative, but the application of UAVs also comes with challenges. Aim In this explorative simulation study, our aim was to develop an efficient layout of UAV surveys that could potentially overcome challenges related to double counts of individuals and even area coverage, and that would minimise off-effort travel costs. Methods Based on different simulated survey layouts we developed hypothetically for the Katavi National Park in Tanzania, we quantified the advantages that UAVs might offer. We then compared these findings with manned aerial surveys. Key results The proposed new survey design and layout indicated an increase in survey efficiency of up to 21% when compared with conventional survey designs using parallel transect lines. Despite the complex flight pattern, the accuracy of the flight paths of the UAV outcompeted those of manned aerial surveys. The adapted survey layout enabled a team of two operators with a small battery-powered UAV to cover an area of up to 1000 km2 per day, without specific infrastructural requirements. Conclusion Our calculations may serve as a vital spark for innovation for future UAV survey designs that may have to deal with large areas and complex topographies while reducing operational effort. Implications UAV applications, if well designed, provide useful complementation, if not replacement, for manned aerial surveys and other remotely sensed data collections. Our suggested survey design is transferable to other study regions, and may be useful for applying UAVs efficiently.
The political polarization of COVID-19 treatments among physicians and laypeople in the United States
Authors: Levin Joel M. , Bukowski Leigh A. , Minson Julia A. , Kahn Jeremy M.
Published: February 2023

In the United States, liberals and conservatives disagree about facts. To what extent does expertise attenuate these disagreements? To study this question, we compare the polarization of beliefs about COVID-19 treatments among laypeople and critical care physicians. We find that political ideology predicts both groups’ beliefs about a range of COVID-19 treatments. These associations persist after controlling for a rich set of covariates, including local politics. We study two potential explanations: a) that partisans are exposed to different information and b) that they interpret the same information in different ways, finding evidence for both. Polarization is driven by preferences for partisan cable news but not by exposure to scientific research. Using a set of embedded experiments, we demonstrate that partisans perceive scientific evidence differently when it pertains to a politicized treatment (ivermectin), relative to when the treatment is not identified. These results highlight the extent to which political ideology is increasingly relevant for understanding beliefs, even among expert decision makers such as physicians.
On Spoken French
Authors: Ashby William J.
Published: February 2023

This scholarly edition invites us to reconsider our assumptions about the French language, by showcasing the oeuvre of one of the pioneers of diachronic Spoken French corpus linguistics, William J. Ashby, and the ground-breaking findings to come out of his influential Tours corpora (1976 & 1995), including two real-time studies appearing for the first time in English translation. To help readers visualize just how radically different the morphosyntax, morphophonology, and semantics of Spoken French are from French-on-the-page, the editor has developed a glossing framework, designed to capture the systemic, radically-prefixal morphology of Spoken French and the variability of change-in-progress. The model, presented here and used to gloss the examples from the Tours corpus, is also suitable for corpus-tagging. The volume is organized into sections preceded by an Editor’s note and followed by suggestions for further reading, and closes with an appendix of French corpora. This scholarly edition was written for advanced undergraduates, graduate students, and scholars in the field.
The syntax, pragmatics, and sociolinguistics of left- and right-dislocations in French
Authors: Ashby William J.
Published: February 2023

Aspects of the syntax, pragmatics and sociolinguistic distribution of left- and right-dislocations in a corpus of spoken French are treated. Most tokens of both types have clear pragmatic motivation, two functions being common to both, with other functions particular to one or another type. The social distribution of weakly motivated tokens does not support the view that, as French moves toward verb-initial typology, dislocated subjects are being grammaticalized as ordinary subjects.
When does variation indicate linguistic change in progress
Authors: Ashby William J.
Published: February 2023

It is argued that two variables of Modern French (the negative particle ne ‘old not’ and the consonant l of clitic pronouns such as il ‘(he); 3sg.m.nom-; 3.nom-; iprs-’) are indeed indices of ongoing linguistic change, even though this change appears to be of long duration. This conclusion is based not only on the distribution of the variables in a corpus of natural French discourse, but also on independent linguistic evidence, together with the available historical record. In the absence of adequate ‘real-time’ data, variationist analysis yielding synchronic, ‘apparent-time’ data provides a useful means of charting the drift of the language.
The variable use of on ‘one’ versus tu/vous ‘you’ for indefinite reference in Spoken French
Authors: Ashby William J.
Published: February 2023

The subject clitic on ‘one’ has a surprising range of referential values, both indefinite (e.g., ‘one,’ ‘they-,’ ‘you-’) and definite (e.g., ‘we-’), that can be seen only when one examines the use of the pronoun in natural discourse. This paper proposes a partial typology of on ‘one’ derived from examples found in a socially-diverse corpus of Tourangeau French. The focus of the paper is on the variable use of on ‘one’ versus vous ‘you- (plural/formal)’ or tu ‘you- (informal)’ as indefinite-generic pronouns (‘y-’). The variation is partially constrained by a complex of linguistic, sociolinguistic, and especially discourse pragmatic factors. The saliency the speaker wishes to give to the referent appears to be a key factor determining the probability of occurrence of the variants.
The loss of the negative morpheme ne in Parisian French
Authors: Ashby William J.
Published: February 2023

Data from a corpus of upper-middle class Parisian French demonstrate that the omission of the negative morpheme ne in negative structures is most frequent among certain demographic segments of the population. This finding, together with historical evidence, suggests that the optional deletion of the negative morpheme ne represents a continuing linguistic change, presaging the eventual total loss of ne – or ‘old not’. This change is most advanced in certain syntactic and phonetic contexts and in informal style.
Towards pragmatic construction typology
Authors: Bychkova Polina , Rakhilina Ekaterina
Published: February 2023

This paper introduces discourse formulae, i.e. frequently used formulaic replies like No way! or You bet!, as an object for linguistic typology. It demonstrates that the frame methodology (Rakhilina & Reznikova 2016) could be applied to these multi-word pragmatic units. The method implies deducing typical situations of use (frames) for a group of synonymous units, and comparing the distributions of these units across frames in different languages. The pilot data includes discourse formulae of negation in Russian, Polish, Slovenian, and Serbian. Six major frames are established. The distributions are obtained with surveys, with Correspondence Analysis applied to the data. The pragmatic parameters influencing the distributions concern the illocutionary type of the preceding utterance, and the speaker’s role in the dialogue.
The use of interjections as a discourse phenomenon
Authors: Nikitina Tatiana , Aplonova Ekaterina , Contreras Roa Leonardo
Published: February 2023

This study describes and compares two conventionalized uses of interjections in traditional narratives in Chuvash (Turkic) and Wan (Mande). First, interjections are shown to be associated with a quotative function: they help signal instances of reported speech. The use of interjections interacts with the grammatical marking of reported speech: the presence of an interjection is negatively correlated with the presence of a grammaticalized quotative element. Second, in Chuvash, but not in Wan, interjections are used, outside the context of reported speech, to emphasize an event’s intensity or duration. We relate the absence of an intensifying function in Wan to competition between interjections and ideophones. The two phenomena shed light on the interaction between interjections and language-specific grammatical and lexical resources.
Polish że ‘that’ as an elaboration marker
Authors: Guz Wojciech , Jędrzejowski Łukasz
Published: February 2023

This chapter discusses a colloquial spoken use of the Polish subordinating conjunction że (lit. ‘that’) as an elaboration marker. Mainly, we argue that że has a core meaning of elaboration spanning a continuum of context-dependent discourse slots. One extreme end of it sees the canonical complementizer tasks, the other one sees the elaboration marker uses operating on the plane of discourse and spoken dialogic interaction. Much of the chapter demonstrates the contrasts between the two types. Additionally, the Polish pattern is reviewed against a cross-linguistic background of elaboration markers in discourse/text as well as a more fine-grained overview of forms signalling both elaboration (in discourse) and complementation (in clause-combining syntax).
A typological study of tail-head linkage constructions
Authors: Olguín Martínez Jesús
Published: February 2023

This paper explores tail-head linkage constructions in a convenience sample of 58 languages. Special attention is paid to recapitulative constructions in which reported speech clauses are omitted and only the quotative verb is recapitulated and summary constructions composed of a light verb accompanied by a deictic and dependency marker. These strategies are more frequent in East Tucanoan languages in the sample. Interestingly, neighboring languages not genetically related to East Tucanoan have both strategies. It is proposed that the most obvious explanation seems to be language contact. This is because: (1) the languages are spoken in the same region, (2) they are not genetically related, and (3) the probability of chance resemblance is low given the rarity of the strategies.