bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling of non-equilibrium suspended sediment transport process in open channel flows with vegetation
Authors: Zhang Song , Yang Zhonghua , Yang Liu , Sun Zhaohua , Zhang Wei
Published: November 2024

A mathematical model based on advection-diffusion theory is established to study the non-equilibrium sediment transport process in vegetated channels. The effects of vegetation on velocity distribution and sediment diffusion coefficients were considered, respectively. Validation against experimental data from flume studies confirms the model's ability to accurately predict the longitudinal sediment deposition rate and the vertical distribution of suspended sediment concentration (SSC). A comparative analysis of three sediment diffusion coefficient formulations indicates that the linear-exponential formula provides a more precise estimate of εsz, and the linear-exponential formula performs well in predicting the turbulent diffusion coefficients of both rigid and flexible vegetation when gently swaying. Moreover, the distance required for SSC to regain equilibrium is influenced by the submergence level of the vegetation canopy. At lower submergence levels, the canopy shear vortices significantly affect the vertical exchange of sediment, and the sediment diffusion coefficients exhibit pronounced stratification near the vegetation canopy. An increase in vegetation density at these lower submergence levels intensifies the shear vortices, thereby extending the distance needed for SSC to reach equilibrium. At higher submergence levels, the impact of canopy shear vortices is lessened, which reduces sediment diffusion coefficient stratification characteristics, and the flow is similar to rough boundary layer flow. An increase in vegetation density increases flow resistance, which shortens the distance required for SSC to attain equilibrium. However, further efforts are required to explore turbulent characteristics with highly flexible vegetation motion and the grain size distribution of non-uniform sediments in vegetated flows.
Improved long-term prediction of chaos using reservoir computing based on stochastic spin–orbit torque devices
Authors: Wang Cen , Lei Xinyao , Cai Kaiming , Ge Xu , Yang Xiaofei , Zhang Yue
Published: November 2024

Predicting chaotic systems is crucial for understanding complex behaviors, yet challenging due to their sensitivity to initial conditions and inherent unpredictability. Probabilistic reservoir computing (RC) is well suited for long-term chaotic predictions by handling complex dynamic systems. Spin–orbit torque (SOT) devices in spintronics, with their nonlinear and probabilistic operations, can enhance performance in these tasks. This study proposes an RC system utilizing SOT devices for predicting chaotic dynamics. By simulating the reservoir in an RC network with SOT devices that achieve nonlinear resistance changes with random distribution, we enhance the robustness for the predictive capability of the model. The RC network predicted the behaviors of the Mackey–Glass and Lorenz chaotic systems, demonstrating that stochastic SOT devices significantly improve long-term prediction accuracy.
Perturbative analysis of the coherent state transformation in ab initio cavity quantum electrodynamics
Authors: Roden Peyton , Foley Jonathan J.
Published: November 2024

Experimental demonstrations of modified chemical structure and reactivity under strong light–matter coupling have spurred theoretical and computational efforts to uncover underlying mechanisms. Ab initio cavity quantum electrodynamics (QED) combines quantum chemistry with cavity QED to investigate these phenomena in detail. Unitary transformations of ab initio cavity QED Hamiltonians have been used to make them more computationally tractable. We analyze one such transformation, the coherent state transformation, using perturbation theory. Applying perturbation theory up to third order for ground state energies and potential energy surfaces of several molecular systems under electronic strong coupling, we show that the coherent state transformation yields better agreement with exact ground state energies. We examine one specific case using perturbation theory up to ninth order and find that coherent state transformation performs better up to fifth order but converges more slowly to the exact ground state energy at higher orders. In addition, we apply perturbation theory up to second order for cavity mode states under bilinear coupling, elucidating how the coherent state transformation accelerates the convergence of the photonic subspace toward the complete basis limit and renders molecular ion energies origin invariant. These findings contribute valuable insights into computational advantages of the coherent state transformation in the context of ab initio cavity quantum electrodynamics methods.
Characterization and quantitative understanding of subthreshold swing of Si metal–oxide–semiconductor field effect transistors at cryogenic temperatures
Authors: Kang Min-Soo , Toprasertpong Kasidit , Oka Hiroshi , Mori Takahiro , Takenaka Mitsuru , Takagi Shinichi
Published: November 2024

The temperature and drain current (ID) dependencies of sub-threshold swing (SS) values of Si n- and p-channel metal–oxide–semiconductor field effect transistors (MOSFETs) with different substrate impurity concentrations ranging from the 1015 to 1018 cm−3 ranges are systematically and experimentally evaluated at cryogenic temperatures. It is found that SS of p-channel MOSFETs tends to increase with decreasing temperature, which contrasts with saturation of SS of n-MOSFETs at cryogenic temperatures, well reported by many previous works. To explain these SS behaviors quantitatively, we employ a density-of-state (DOS) model with tail states consisting of localized states in a deep energy range and mobile states in a shallow energy range, which are attributable to potential fluctuations caused by substrate impurities. It is shown that this model can quantitatively explain the temperature and ID dependencies of SS of both n-MOSFETs and p-MOSFETs. Then, we are assuming that the Si p-MOSFET has a higher density of localized states than the n-MOSFET. Thus, the increase in SS of the p-MOSFETs with decreasing temperature is explained by an increase in the density of localized states at the Fermi level with decreasing temperature, because the density of localized states increases with elevating the Fermi level position in the employed DOS model.
Investigation of resistive switching behavior driven by active and passive electrodes in MoO2–MoS2 core shell nanowire memristors
Authors: Yadav Renu , Poudyal Saroj , Biswal Bubunu , Rajarapu Ramesh , Barman Prahalad Kanti , Novoselov Kostya S. , Misra Abhishek
Published: November 2024

Memristive devices based on layered materials have the potential to enable low power electronics with ultra-fast operations toward the development of next generation memory and computing technologies. Memristor performance and switching behavior crucially depend on the switching matrix and on the type of electrodes used. In this work, we investigate the effect of different electrodes in 1D MoO2–MoS2 core shell nanowire memristors by highlighting their role in achieving distinct switching behavior. Analog and digital resistive switching are realized with carbon based passive (multi-layer graphene and multiwall carbon nanotube) and 3D active metal (silver and nickel) electrodes, respectively. Temperature dependent electrical transport studies of the conducting filament down to cryogenic temperatures reveal its semiconducting and metallic nature for passive and active top electrodes, respectively. These investigations shed light on the physics of the filament formation and provide a knob to design and develop the memristors with specific switching characteristics for desired end uses.
Effects of non-Newtonian models on viscosity of unsteady aortic blood flow
Authors: Qiao Yonghui , Sun Yifan , Guo Hengjie , Pan Zhouzhou , Wang Shuai , Fan Jianren , Luo Kun
Published: November 2024

Computational hemodynamics plays a crucial role in reproducing the details of aortic blood flow. However, the application of the non-Newtonian viscosity model is still controversial. The objective of this study is to demonstrate the effects of different non-Newtonian models on the viscosity of blood flow in healthy aorta. First, we reconstructed the three-dimensional geometric models of two healthy aortas based on computed tomography angiography images. The blood flow waveform with parabolic distribution and the three-element Windkessel model were adopted as boundary conditions. Then, the interaction between the blood flow and hyperelastic aortic vessel wall was considered by the two-way fluid–structure interaction method. Finally, we chose four commonly used non-Newtonian viscosity models: the Quemada model, Casson model, Carreau, and Carreau–Yasuda models. Results show that the instantaneous low shear strain rate (SSR < 100 s−1) cannot be neglected considering its relatively high proportion in the aortic wall (50%) and cardiac cycle (33%). We find that the Quemada model can predict the shear-thinning properties of aortic blood flow, especially the relatively low viscosity distribution. Besides, the high-viscosity iso-surface is observed in the descending aorta throughout the cardiac cycle. The phenomena further underline that the Newtonian assumption is not suitable for predicting the viscosity distribution of aortic blood flow. In conclusion, the non-Newtonian viscosity model is suggested to be adopted in aortic computational hemodynamics, and the performance of the Quemada model is satisfactory.
Up to 60% energy saving for GST-based confined phase change memory using paired pulses RESET operation scheme
Authors: Cao Ze-Hua , Wang Xi , Zhu Rong-Jiang , Liu Zi-Yang , Xu Ming , Tong Hao , He Qiang , Miao Xiang-Shui
Published: November 2024

As one of the most promising candidates for next-generation nonvolatile memory, phase change memory is still facing the problem of high power consumption required to reset the device. The melt-quench process during amorphization leads to thermal crosstalk between devices as well. In this work, a paired pulses (P.P.) RESET operation scheme has been demonstrated to reduce the maximum temperature during the amorphization process, which in turn significantly reduces the power consumption. Experiments show that both the minimum RESET programming voltage and power consumption have decreased by up to 0.4 V and 60%, respectively. This proposed programming strategy is promising to optimize the device endurance and stability without sacrificing operating speed.
Effects of mass diffusion on Rayleigh–Taylor instability under a large gravity
Authors: Guo Y. , Wu D. , Zhang J.
Published: November 2024

Rayleigh–Taylor instabilities (RTI) play an important role in the evolution of inertial confinement fusion (ICF) processes, while analytical prediction of the RTI growth rate often fails to reach an agreement with the experimental and simulation results. Accurate analytical prediction of RTI growth is of great significance to the success of ICF schemes. In this paper, we study the effects of mass diffusion and exponential density distribution on RTI under a large gravity by solving the Rayleigh equation with a linear approximation to the density distribution of the mixing layer. The width of the mixing layer is assigned by evaluating the length scale of concentration diffusion and gravitational sedimentation. The latter term is missing in the former isobaric diffusion treatment and is supposed to change the structure of the mixing layer under the gravity. While both effects tend to dampen the instability growth, mass diffusion dominates the damping of perturbations of larger wavenumber and exponential density distribution dominates those of smaller wavenumber, resulting in a non-monotonicity of the density suppression factor of the instability growth rate over perturbation wavenumbers.
Electromagnetic scattering by curved surfaces and calculation of radiation force: Lattice Boltzmann simulations
Authors: Khan Mohd. Meraj , Thampi Sumesh P. , Roy Anubhab
Published: November 2024

This study aims to investigate the effectiveness of the lattice Boltzmann method (LBM) in studying the scattering of electromagnetic waves by curved and complex surfaces. The computation of Maxwell’s equations is done by solving for a pair of distribution functions, which evolve based on a two-step process of collision and streaming. LBM bypasses the need for expansion via vector spherical harmonics and thus is amenable to scatterers with complex geometries. We have employed LBM to compute the scattering width and radiation force for perfect electrically conducting and dielectric cylinders of circular and elliptical cross sections. Both smooth and corrugated surfaces are studied, and the results are compared against known analytical and numerical solutions from other methods. To ensure the broad applicability of the method, we have explored a wide range of parameter space—the dielectric constant and particle size to the wavelength ratio spanning Rayleigh, Mie, and geometrical optics regimes. Our simulations have successfully reproduced well-known analytical and numerical solutions, confirming the accuracy and reliability of the LBM for scattering calculations by complex-shaped objects.
Bosonic Mpemba effect with non-classical states of light
Authors: Longhi Stefano
Published: November 2024

The Mpemba effect (ME) refers to the surprising observation where, under certain conditions, a far-from-equilibrium state can relax toward equilibrium faster than a state closer to equilibrium. A paradigmatic example is provided by the curious fact that hot water can sometimes freeze faster than cold water. The ME has intrigued scientists for a long time and has been predicted and observed in a variety of classical and quantum systems. Recently, the search for Mpemba-like effects of purely quantum nature has raised a major interest. Here, we predict the emergence of ME in the quantum optics context exploiting non-classical states of light. By analyzing the decay dynamics of photon fields in a leaky optical resonator or waveguide, it is demonstrated that bosonic ME emerges in the context of the quantum nature of light. In particular, the relaxation dynamics are strongly influenced by the photon statistics of the initially trapped light field. The ME is observed when comparing the decay dynamics of classical light fields (coherent states) with certain non-classical states, such as Fock states, squeezed states, and Schrödinger cat states.
Topological one-way edge states in locally resonant metamaterials
Authors: Xiao Ding-Yi , Xie Yu-Xin , Wang Yue-Sheng
Published: November 2024

The quantum anomalous Hall effect (QAHE) enables dissipation-free motion within its edge states, offering considerable potential for developments in the fields of electronics, phononics, and elastic waves. In this study, we introduce an elastic metamaterial designed to realize the QAHE at low frequencies. Our approach involves deploying a two-dimensional honeycomb spring-mass system on a rotating platform to break time-reversal symmetry via the Coriolis Force and incorporating local resonators to achieve low-frequency topological edge states. We begin by deriving the system’s equations of motion through analytical rigid body dynamics. Subsequently, we apply Bloch wave solutions to establish the dispersion relations and identify the topological edge states. We then conduct numerical simulations to confirm the one-way transmission characteristics of these states. The addition of local resonators not only extends the frequency range of the topological edge states but also lowers the operational frequency of the system. This robust waveguide, capable of one-way transmission, has potential applications in directional transmission, vibration damping, noise reduction, and acoustic imaging.
Pulsed N2 plasma surface treatment for AlGaN/GaN HEMTs prior to PECVD SiNx passivation to reduce plasma damage
Authors: Wang Kaiyu , Wei Ke , Zhang Ruizhe , Zhang Sheng , Guo Jiaqi , He Xiaoqiang , Wang Jianchao , Huang Sen , Zheng Yingkui , Chen Xiaojuan , Wang Xinhua , Liu Xinyu
Published: November 2024

In this work, a pulse-mode N2 plasma surface treatment process was proposed as a means of reducing plasma damage and improving the GaN/GaOx ratio on the surface before SiNx deposition, which further contributes to an enhanced density of 2DEG and a reduced sheet resistance. With the pulsed N2 plasma surface treatment combined with subsequent SiNx passivation, the fabricated GaN HEMTs exhibit negligible current collapse and suppressed leakage current. The improved behavior is attributed to the fact that the pulsed N2 plasma is capable of nitriding the surface and removing carbon contaminants as identified through x-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy. Compared to the traditional continuous-wave-mode N2 plasma, the pulsed N2 plasma pre-treatment effectively prevents continuous collisions of the plasma during acceleration, thereby significantly reducing plasma damage. This work offers valuable insights for surface treatment processes in micro- and nanofabrication.
The role of conduction band electrons in promoting O2 adsorption to silicon interfaces
Authors: McNally Marshall T. , Pineda Agustin A. , Walker Robert A.
Published: November 2024

Resonance enhanced Second Harmonic Generation (SHG) was employed to assess if conduction band electrons in silicon (Si) will promote molecular adsorption of ambient species and how such adsorption depends on temperature. Experiments were performed with three types of Si (n-doped or n-Si, p-doped or p-Si, and undoped Si) at temperatures between 18 and 260 °C and under atmospheres of dry N2 and dry (cylinder) air. All Si types were covered with a 2–4 nm thick native oxide layer. Under N2, all Si types behave similarly, with SHG intensity [I(2ω)] diminishing with increasing temperature. This effect was reversible and attributed to electron–phonon scattering. In the presence of O2, I(2ω) from n-Si at room temperature is enhanced significantly. Neither p-doped Silicon (p-Si) nor undoped Si show similar effects at room temperature, with I(2ω) being independent of gas phase composition. At temperatures ≥175 °C, all three Si types behaved similarly with no dependence on atmospheric O2 content. Varying the amount of O2 above n-Si at room temperature and measuring I(2ω) suggested that O2 adsorption to n-Si could be described with a Langmuir isotherm and an adsorption energy of −0.13 ± 0.05 eV. Increasing n-Si’s oxide thickness (to 600 nm) rendered the substrate insensitive to ambient gas phase composition. Taken together, these findings support a description of Si’s surface electronic structure that is controlled by n-Si conduction band electrons backbonding into the π* orbitals of adjacent O2 and imply that these conduction band electrons can affect adsorption despite the presence of a native oxide film.
Numerical investigation of turbulent flow over a randomly packed sediment bed using a variable porosity continuum model
Authors: Karra Shashank K. , Apte Sourabh V.
Published: November 2024

A large eddy simulation (LES) is performed for a turbulent open channel flow over a porous sediment bed at permeability Reynolds number of ReK∼2.56 (Reτ = 270) representative of aquatic systems. A continuum approach based on the upscaled, volume-averaged Navier−Stokes (VaNS) equations is used by defining smoothly varying porosity across the sediment water interface (SWI) and modeling the drag force in the porous bed using a modified Ergun equation with Forchheimer corrections for inertial terms. The results from the continuum approach are compared with a pore-resolved direct numerical simulation (PR-DNS) in which turbulent flow over a randomly packed sediment bed of monodispersed particles is investigated [Karra et al.,J. Fluid Mech. 971, A23 (2023)] A spatially varying porosity profile generated from the pore-resolved DNS is used in the continuum approach. Mean flow, Reynolds stress statistics, and net momentum exchange between the freestream and the porous bed are compared between the two studies, showing reasonably good agreement. Small deviations within the transitional region between the sediment bed and the freestream as compared to the PR-DNS results are attributed to the local protrusions of particles in a randomly packed bed that are absent in the continuum approach but are present in the PR-DNS. A better representation of the effective permeability in the top transition layer that accounts for roughness effect of exposed particles is necessary. The continuum approach significantly reduces the computational cost, thereby making it suitable to study hyporheic exchange of mass and momentum in large scale aquatic domains with combined influence of bedform and bed roughness.
Effects of chamfering and spacing on aerodynamics of two tandem cylinders
Authors: Zhou Qiang , Shang Jingmiao , Alam Md. Mahbub , Li Huan
Published: November 2024

The flow over two tandem cylinders is investigated with five different spacing ratios L/D = 1.25, 2.0, 3.5, 4.0, and 6.0 and four chamfered-corner ratios ξ = B/D = 0%, 5%, 10%, and 15% at a Reynolds number Re = 5300, where L, B, and D are the distance between cylinders, chamfered corner dimension, and cylinder width, respectively. This work aims to assimilate the effects of ξ and L/D on flow structures, vortex shedding, aerodynamic forces, Strouhal number, and their relationships. We identified three different flow patterns depending on ξ and L/D: overshoot flow (L/D = 1.25, ξ  = 0%), reattachment flow (1.25–2.0 ≤ L/D ≤ 2.0–3.5, ξ = 0%–15%), and coshedding flow (L/D ≤ 2.0–3.5, ξ = 0%–15%). The ξ and L/D play a similar role in the qualitative change of the flow structures, albeit with different degrees. As such, when L/D or ξ is increased, an overshoot/reattachment flow may change to a reattachment/coshedding flow. With the same flow pattern, ξ has a greater influence on the aerodynamic facets than L/D. This study establishes a framework for understanding how ξ and L/D influence flow topology and aerodynamic parameters.
Connecting the liquid fragility to the average weakest metal–oxygen bond of its crystal in oxides
Authors: Xu Di , Xiang Jichun , Zheng Haibing , Wang Li-Min , Liu Xin , Chen Ling , Wu Liming , Li Weihua
Published: November 2024

Glass and crystal are inherently different material states in terms of their structural and physical features; consequently, the direct quantitative connection between crystal and glass is lacking. Herein, we first show that the liquid fragility m, which is featured by the negative departure degree of viscosity with the temperature at the glass transition temperature (Tg), has a direct exponential correlation with the ratio of the average longest metal–oxygen and the average phosphorus, silicon, or boron–oxygen bond lengths of the crystal in various oxides including phosphates, silicates, and borates. Such a result can be rationalized by the fact that the fragility m in these glass-formers is associated with the total network rigidity determined by the weakest bond due to the “bucket effect” and the bond pair inheritance of glass from that of the crystal. Our work connects direct features between glass and crystal with identical composition, providing a new viewpoint bridging glass and crystal.
Two complementary eigen-based geometric properties of a vortex
Authors: Kolář V. , Šístek J.
Published: November 2024

In our previous paper [V. Kolář and J. Šístek, “Orbitally compact and loose vortex regions,” Phys. Fluids 35, 121708 (2023)], the eigenvalue-based measure of orbital compactness of particle motion inside a vortex for compressible flows has been proposed. Here, a complementary eigenvector-based geometric property of cylindricity (three-dimensional /3D/ aspect) is introduced. This property is closely related to the local flow axisymmetry in the swirl plane (two-dimensional /2D/ aspect) which explains the positive response of the vortex-identification Δ-criterion, and closely related criteria swirling strength and Rortex (Liutex), for almost no vorticity and a large (without any limitation) rate-of-strain magnitude. A relatively high correlation between orbital compactness, cylindricity, and widely used vortex-identification criteria has been found for several flow examples.
Scattering of ultrashort x-ray pulses in optically dense plasmas: Account for pulse duration and propagation effects
Authors: Rosmej F. B. , Astapenko V. A. , Lisitsa V. S.
Published: November 2024

Scattering of ultrashort laser pulses (USP) in optically dense plasma is presented, accounting for the peculiarities of ultrashort electromagnetic interaction and absorption of radiation in plasmas. The results are presented in terms of a universal dimensionless total scattering coefficient (TSC). A universal closed expression for TSC is derived and analyzed. Numerical calculations of TSC are carried out for the special case of USP resonance scattering on H-like ions in hot plasmas. Fine structure splitting of the resonant transition and Doppler broadening are taken into account. The dependences of the TSC on USP parameters and the optical thickness of plasma layers are derived.
Enhancing flow uniformity and reducing turbulent kinetic energy in refrigerator freezers through magnetic resonance velocimetry-based structural modifications
Authors: Dong Hangfei , Im Chaehyuk , Kang Chiho , Song Simon
Published: November 2024

High energy efficiency and low operational noise are increasingly demanded in premium household appliances. Magnetic resonance velocimetry (MRV) has recently emerged as a versatile flow visualization technology, particularly suited for the efficient design of such appliances. This study conducted a comprehensive analysis of a 3/5 scale freezer model, incorporating the cooling system, compartment, and cabinets, all fabricated using stereolithography three-dimensional (3D) printing. By focusing on flow characteristics, 3D mean velocity and turbulent kinetic energy (TKE) fields were measured, identifying regions of non-uniform flow and elevated TKE. To address these issues, structural modifications were introduced in an improved model. These modifications included refining the central structure of the fan chamber, altering inlet geometries, and adding a fillet at the inlet edge. The results were significant: a more uniform flow distribution was achieved, with a 15 percentage-point increase in the effective flow rate through the evaporator's finned area, a reduction in secondary flow energy in the fan chamber, and a substantial decrease in TKE. Consequently, the improved model demonstrated enhanced energy efficiency and quieter operation. These findings highlight the potential of MRV as an effective tool for analyzing complex flow systems in appliance design.
Effects of low temperature on near-nozzle breakup and droplet size distribution in airblast kerosene spray
Authors: Zhao Yue , Wang Yu , Zhang Hang , Li Tianxiong , Song Ge , Liu Tao , Chen Si , Wu Yingchun , Wu Xuecheng
Published: November 2024

Atomization of low-temperature fuel is encountered in extreme operating conditions of liquid propulsion systems such as cold start and high-altitude relight for aeroengines. Fuel temperature has a great impact on airblast spray characteristics by influencing fuel viscosity and thus the gas–liquid interaction, which raises the demand to clarify the temperature-dependent transition in near-nozzle breakup behavior and the corresponding droplet size distribution. A liquid-centered swirl coaxial injector is tested on the low-temperature swirl spray and combustion test rig at Zhejiang University, using 25 kHz high-speed digital off-axis holography. RP-3 aviation kerosene is atomized under ignition conditions at temperatures of 233, 253, and 301 K, fuel pressures of 0.03 and 0.69 MPa, and air pressure ranging from 0 to 4.0 kPa. Time-resolved near-nozzle dynamics suggest four types of elementary breakup processes: wavy-sheet breakup, pulsating breakup, membrane-type breakup, and nonaxisymmetric Rayleigh breakup. Each process alternately dominates the near field as fuel Reynolds number (Ref) and aerodynamic Weber number (Weg) decrease, corresponding to four primary breakup modes. A mode classification plot is summarized. Spray structures show an extended breakup length and reduced spray cone angle as fuel temperature (Tf) decreases. Increasing air pressure (Pg) promotes spray expansion at 0.03 MPa, but contracts spray cone at 0.69 MPa. Cross-sectional Sauter mean diameter (SMD) distribution indicates a solid-cone spray at 0.03 MPa and a hollow cone spray at 0.69 MPa. Lowering Tf will rise the SMD in the spray center at 0.03 MPa and transform the toroidal SMD distribution at 0.69 MPa into a solid one. Finally, a temperature-related SMD model is derived considering the exponential viscosity–temperature relationship, and a good fit with R2 > 0.95 is achieved. This research aims to deepen the understanding of the effects of low temperature on the transition of near-nozzle atomization characteristics for airblast sprays. Both spray visualization and SMD results provide reference for numerical simulations and near-nozzle spray modeling.
Intelligent microwave absorption of VO2@PDA/RGO composites based on dynamic interfacial polarization performance
Authors: Ma Long , Si Haoxu , Feng Kailin , Pan Zhihao , Hao Xicai , Li Cuiping , Gong Chunhong , Zhang Jingwei
Published: November 2024

To design smart microwave-absorbing materials (MAMs), it is essential to adjust the corresponding electrical conductivity and dielectric parameters according to variable conditions. However, it is still challenging to concurrently adjust the effective absorbing intensity and frequency range in MAMs due to their interdependent constraints. Here, we developed intelligent MAMs by incorporating core–shell structure vanadium dioxide @ polydopamine (VO2@PDA) powders as polarization loss units, while the subwavelength-sized reduced graphene oxide microspheres (RGOms) were used as conduction loss units. When the temperature is higher than the metal–insulator phase transition temperature of the insulator state VO2 (M), the corresponding metal state VO2 (R) could be produced, which, therefore, contributes to an enhanced interfacial polarization loss due to the significant electrical performance differences between the VO2 (R) and the PDA shell. As an optimized result, the changes of the effective absorption frequency band (▵EAF) and reflection loss (▵RL) of the RV3 composite could be approximately 1.5 GHz and 24 dB, respectively, attributable to the phase transition of VO2. This study provides a novel approach for the adjustment of electromagnetic responses based on dynamic interfacial polarization performance, which offers broader prospects for developing next-generation smart electromagnetic absorption devices with both reversible microwave absorption frequency range and intensities.
Numerical study of internal solitary wave loads on a submerged slender body with multi-parameter coupling
Authors: Wang Runze , Zhi Changhong , You Yunxiang
Published: November 2024

This study investigates the destabilizing loads exerted on submarines by large-amplitude internal solitary waves (ISWs), which significantly increase the risk of a phenomenon known as “falling deep.” Using numerical simulations and theoretical analysis, the research explores the multi-parameter coupling effects of ISWs on a slender body in a two-layer fluid system. A numerical wave generation method for large-amplitude ISWs, based on the strongly nonlinear adjusted high-order unidirectional (aHOU) model, is proposed. A corresponding numerical model is also developed to simulate the interaction between ISWs and a submerged slender body, with validation against experimental data confirming its accuracy and reliability. The study further examines how wave amplitude, submergence depth, and wave incidence angle affect the load characteristics induced by ISWs. Theoretical analysis identifies the components of ISW-induced loads, revealing a linear relationship between horizontal load and wave amplitude, as well as the influence of submergence depth on the duration of vertical forces. The primary contributor to the horizontal force is identified as the pressure-gradient force generated by the ISW's flow field, while the vertical force is primarily driven by the reduced gravity force due to density stratification and wave forces, which are well-approximated by Morison's formula. Additionally, the peak values of horizontal and vertical forces are significantly affected by wave incidence angle and wave amplitude, respectively. These findings provide a theoretical foundation for understanding the “falling deep” phenomenon encountered by submarines under the influence of ISWs.
Pore-scale study on shear rheology of wet granular materials
Authors: Fei Linlin , He Ya-Ling , Derome Dominique , Carmeliet Jan
Published: November 2024

We study pore-scale rheological phenomena in two-dimensional sheared wet granular materials. Simulations use a coupled cascaded lattice Boltzmann and discrete element method, to model the liquid–gas multiphase flows and multiple-solid-particle dynamics, respectively. The wet granular material is prepared by first filling a rectangular domain with solid particles and then partially filling the pores between the particles with the liquid phase. The material is then sheared based on standard Couette flow configuration, i.e., with lid-driven velocities U and -U on the top and bottom walls, respectively. The simulations show that the apparent viscosity of the system attains a minimum when the material is wet but not fully saturated, i.e., at a saturation of ∼0.10. Such an observation is coherent both for materials composed of monodisperse and polydisperse particles. Interestingly, this observation coincides with the experimental finding of the decrease in sliding friction on sand by adding a small amount of water. The underlying mechanism is elucidated based on the pore-scale study of liquid patch dynamics. It is shown that, with increasing liquid saturation, the rheology of the wet granular materials is affected by two competing effects: (i) a larger number of liquid patches appear leading to fluidization of the system and (ii) larger patches are formed, clogging the flow. The minimum apparent viscosity saturation of ∼0.10 coincides with the maximum of the product of the two factors: the number of liquid patches and ratio between the system height and largest patch height.
Tunable macroscopic self-healing of supramolecular gel through host–guest inclusion
Authors: Li Zhe , Hao Jiting , Lu Yao , Hu Wenchao , Jiang Haizhuang , Zhou Bobo , Yang Hongbin , Kang Wanli , Sarsenbekuly Bauyrzhan
Published: November 2024

Supramolecular gels (SGs) consisted of noncovalent cross-linking network structures are fascinating due to their efficient energy dissipation and reversible self-healing properties. However, it is unknown how the noncovalent interactions alter the macroscopic self-healing and mechanical properties of SGs. Herein, the peculiar nature of SGs manufactured by combining covalent and noncovalent (host–guest inclusion of β-cyclodextrin and C16 hydrophobic chain) cross-linking structures was studied and compared with covalent cross-linking preformed particle gels. The macroscopic self-healing behaviors, rheology, mechanical tensile properties, as well as the tunable mechanisms of self-healing were explored by visual inspection, rheological, and atomic force microscopy probing methods. The results show that the SGs exhibit excellent self-healing efficiency and mechanical strength after interfacial cutting. Moreover, the SGs exhibited excellent mechanical tensile properties, including loading–unloading, successive loading–unloading, and recovery loading–unloading tensile performances. Notably, the macroscopic self-healing of SGs has good tunability by changing the covalent and noncovalent crosslinker contents and salt contents. This peculiar phenomenon is attributed to certain host–guest inclusion forces (4.7 and 0.3 nN) between different SGs under the distilled and high-salinity water conditions, respectively. This study is beneficial for the development of stimuli–response supramolecular gels in different applications, such as oil recovery in fractured reservoirs.
Addressing unnecessary and avoidable transfers from residential aged care to emergency departments and hospitals
Authors: Peters Micah DJ , Clarke Jarrod , Marnie Casey
Published: November 2024

Purpose The purpose of this article is to examine and discuss the literature regarding emergency department (ED) transfers from residential aged care with a focus on reducing potentially avoidable transfers to enhance care experiences, safety, and outcomes. Design Researchers experienced in evidence synthesis and policy research in the aged care space reviewed the literature about residential aged care transfers to EDs, including factors underlying transfers and interventions to reduce transfers. Findings Transfers to EDs from aged care are common. They can be harmful, distressing, costly, and have a variety of negative impacts on residents, staff, and the aged care and health system. High rates of potentially avoidable or unwarranted transfers suggests the presence of systemic issues, including the lack of sufficient staffing levels and skills mix with the requisite knowledge, training, resources, and support. Reforms are required to improve staffing levels and skills mix, enhance access to on-site and in-reach clinical expertise, provide access to quality improvement initiatives, and engage consumers to ensure shared decision-making. Further research is also required to help determine the best approach to reducing unnecessary hospital transfers from aged care considering the specific scopes of practice of aged care workers. Conclusion While some transfers from residential aged care to EDs are necessary, many do not represent safe, dignified care for older people. Unwarranted transfers are burdensome and risky and should be minimised through the provision of a range of reforms including sufficient staffing, resources, and support, that allow for the delivery of care in place where appropriate.
A digitally enabled health workforce for Australia
Authors: Janssen Anna , Baysari Melissa , Igasto Christina , Quirke Kate , Milnes Petra , Shaw Tim , Dunn Adam
Published: November 2024

Australia has world-class education for healthcare professionals and is recognised for its strength in digital health research but is yet to fill some important gaps in training healthcare professionals in the safe implementation and use of digital technologies. In this case study, we bring together the perspectives of clinicians, health system leaders, and academics to guide efforts in establishing a digitally enabled workforce in Australia. Building on published evidence, our recommendations include leveraging on recent momentum, building strong partnerships with healthcare organisations, academia, and the digital health industry, and ultimately an expansion of a digitally enabled clinical informatics and digital health workforce.
Timor-Leste: preliminary assessment of a rapidly eroding landscape in the Coral Triangle
Authors: Wasson R. J. , Amaral A. L. , Rouwenhorst J. , Fifield K. , Chauhan N. , Pietsch T. , Alongi D. M. , Tirendi F. , Singhvi A. K.
Published: November 2024

Context Sedimentation in the rivers and on the coasts of Timor-Leste has increased since deforestation, affecting floods and probably living aquatic resources. Aims To provide scientifically based estimates of long-term and short-term erosion rates to assess the apparent role of deforestation, a topic that has not received sufficient quantitative attention in the Coral Triangle. Methods Short-term erosion rates have been estimated from regional relationships between river sediment yield and catchment areas and cosmogenic nuclides for long-term rates. An attempt has also been made to estimate changes in rates of delta progradation to determine whether recent increases have occurred following deforestation. Key results The major scientific finding is that reduction in vegetation cover for agriculture and timber harvesting, particularly in the mountains, increased sediment yield by factors up to 120, mainly by landsliding. And there has been a large amount of sediment exported to the delta and offshore from river-channel change. Implications Impacts on living resources are likely both in rivers and on the coast, but require assessment. Revegetation of hillslopes is likely to reduce these impacts and improve the livelihoods of local people.
Trade-offs, control conditions, and alternative designs in the experimental study of cultural evolution
Authors: Derex Maxime , Edmiston Pierce , Lupyan Gary , Mesoudi Alex
Published: November 2024

Although the theoretical foundations of the modern field of cultural evolution have been in place for over 50 y, laboratory experiments specifically designed to test cultural evolutionary theory have only existed for the last two decades. Here, we review the main experimental designs used in the field of cultural evolution, as well as major findings related to the generation of cultural variation, content- and model-based biases, cumulative cultural evolution, and nonhuman culture. We then identify methodological advances that demonstrate the iterative improvement of cultural evolution experimental methods. Finally, we focus on one common critique of cultural evolution experiments, the appropriate individual learning control condition needed to demonstrate cumulative culture, and present an original experimental investigation relevant to this critique. Participants completed a combinatorial innovation task allowing for cumulative improvement over time in one of four commonly used experimental designs/conditions: social learners in chains, social learners in groups, individual learners experiencing an extended session lasting the same accumulated time as an entire chain or group, and individual learners experiencing repeated sessions adding up to the same total time. We found that repeated individual learning resulted in superior performance to any other condition. We discuss these findings in light of the relevance of the specific criticism of previous experimental studies that purport to have demonstrated cumulative culture. We also use our findings to discuss the broad trade-offs that participants face when learning individually and socially in different contexts, including variable acquisition costs, redundancy of effort in groups, and cognitive and motivational fatigue.
Genetic differentiation and precolonial Indigenous cultivation of hazelnut (
Corylus cornuta
, Betulaceae) in western North America
Authors: Armstrong Chelsey Geralda , Clemente-Carvalho Rute B. G. , Turner Nancy J. , Wickham Sara , Trant Andrew , Lemay Matthew A.
Published: November 2024

Cultivation studies evaluating land-use histories and coevolutionary dynamics between humans and plants focus predominantly on domesticated species. Traditional anthropological divisions of “foragers” and “farmers” have shaped our understanding of ancient cultivation practices but have several limitations, including how people stewarded and managed nondomesticated species. To investigate the long-term effects of plant management in the Pacific Northwest, this study focuses on beaked hazelnut (
Corylus cornuta
) which has a long, precolonial history of management, transportation, and cultivation in British Columbia (BC, Canada). In particular, isolated hazelnut populations in northwestern BC are thought to be the result of historical transplanting and management. We sampled individual hazelnuts (n = 219) representing three distinct regions in and assessed 9,650 genome-wide SNPs identified with nextRAD genotyping-by-sequencing libraries to test for population genetic structure. We used linear measurements of individuals to assess morphological phenotypes and to identify variation between individuals and lineages. These data reveal shared genetic clusters in distant and disjunct northwestern and interior regions consistent with the movement of humans across the landscape. We also find several small genetically distinct populations in the northwestern region. The Genetic structure of hazelnut in the previously labeled “disjunct” region in Gitxsan, Ts’msyen, and Nis
g
a’a homelands is consistent with the enduring influence of people on the distribution of purportedly “wild” plant species. Our results support the hypothesis that hazelnut was likely transplanted long distances and also managed in situ. This study highlights the often-overlooked agency of Indigenous Peoples in shaping species range distributions in North America.
Realistic binary neutron star initial data with Elliptica
Authors: Rashti Alireza , Noe Andrew
Published: November 2024

This work introduces the Elliptica pseudo-spectral code for generating initial data of binary neutron star systems. Building upon the recent Elliptica code update, we can now construct initial data using not only piecewise polytropic equations of state, but also tabulated equations of state for these binary systems. Furthermore, the code allows us to endow neutron stars within the binary system with spins. These spins can have a magnitude close to the mass shedding limit and can point in any direction.
A strategy for achieving optimisation of radiological protection in digital radiology proposed by ICRP
Authors: Martin Colin J , Kortesniemi Mika K , Sutton David G , Applegate Kimberly , Vassileva Jenia
Published: November 2024

Radiology is now predominantly a digital medium and this has extended the flexibility, efficiency and application of medical imaging. Achieving the full benefit of digital radiology requires images to be of sufficient quality to make a reliable diagnosis for each patient, while minimising risks from radiation exposure, and so involves a careful balance between competing objectives. When an optimisation programme is undertaken, a knowledge of patient doses from surveys can be valuable in identifying areas needing attention. However, any dose reduction measures must not degrade image quality to the extent that it is inadequate for the clinical purpose. The move to digital imaging has enabled versatile image acquisition and presentation, including multi-modality display and quantitative assessment, with post-processing options that adjust for optimal viewing. This means that the appearance of an image is unlikely to give any indication when the dose is higher than necessary. Moreover, options to improve performance of imaging equipment add to its complexity, so operators require extensive training to be able to achieve this. Optimisation is a continuous rather than single stage process that requires regular monitoring, review, and analysis of performance feeding into improvement and development of imaging protocols. The ICRP is in the process of publishing two reports about optimisation in digital radiology. The first report sets out components needed to ensure that a radiology service can carry optimisation through. It describes how imaging professionals should work together as a team and explains the benefits of having appropriate methodologies to monitor performance, together with the knowledge and expertise required to use them effectively. It emphasises the need for development of organisational processes that ensure tasks are carried out. The second ICRP report deals with practical requirements for optimisation of different digital radiology modalities, and builds on information provided in earlier modality specific ICRP publications.