A 1D finite element method in time domain is developed in this paper and applied to calculate in-plane wave motions of free field exited by SV or P wave oblique incidence in an elastic layered half-space. First, the l...A 1D finite element method in time domain is developed in this paper and applied to calculate in-plane wave motions of free field exited by SV or P wave oblique incidence in an elastic layered half-space. First, the layered half-space is discretized on the basis of the propagation characteristic of elastic wave according to the Snell law. Then, the finite element method with lumped mass and the central difference method are incorporated to establish 2D wave motion equations, which can be transformed into 1D equations by discretization principle and explicit finite element method. By solving the 1D equations, the displacements of nodes in any vertical line can be obtained, and the wave motions in layered half-space are finally determined based on the characteristic of traveling wave. Both the theoretical analysis and the numerical results demonstrate that the proposed method has high accuracy and good stability.展开更多
The analysis method of lattice dynamics in classical physics is extended to study the properties of in-plane wave motion in the hybrid-mass finite element model in this paper. The dispersion equations of P and SV wave...The analysis method of lattice dynamics in classical physics is extended to study the properties of in-plane wave motion in the hybrid-mass finite element model in this paper. The dispersion equations of P and SV waves in the discrete model are first obtained by means of separating the characteristic equation of the motion equation, and then used to analyse the properties of P-and SV-homogeneous, inhomogeneous waves and other types of motion in the model. The dispersion characters, cut-off frequencies of P and SV waves, the polarization drift and appendent anisotropic property of wave motion caused by the discretization are finally discussed.展开更多
In this paper, a method based on the Dirichlet- to-Neumann map is developed for bandgap calculation of mixed in-plane waves propagating in 2D phononic crystals with square and triangular lattices. The method expresses...In this paper, a method based on the Dirichlet- to-Neumann map is developed for bandgap calculation of mixed in-plane waves propagating in 2D phononic crystals with square and triangular lattices. The method expresses the scattered fields in a unit cell as the cylindrical wave expansions and imposes the Bloch condition on the boundary of the unit cell. The Dirichlet-to-Neumann （DtN） map is applied to obtain a linear eigenvalue equation, from which the Bloch wave vectors along the irreducible Brillouin zone are calculated for a given frequency. Compared with other methods, the present method is memory-saving and time-saving. It can yield accurate results with fast convergence for various material combinations including those with large acoustic mismatch without extra computational cost. The method is also efficient for mixed fluid-solid systems because it considers the different wave modes in the fluid and solid as well as the proper fluid-solid interface condition.展开更多
Transient S wave velocity rupture (TSVR) means the velocity of fault rupture propagation is between S wave velocity α and P wave velocity β . Its existing in the rupture of in plane ( i.e . strike slip...Transient S wave velocity rupture (TSVR) means the velocity of fault rupture propagation is between S wave velocity α and P wave velocity β . Its existing in the rupture of in plane ( i.e . strike slip) fault has been proved, but in 2 dimensional classical model, there are two difficulties in transient S wave velocity rupture, i.e ., initialization difficulty and divergence difficulty in interpreting the realization of TSVR. The initialization difficulty means, when v ↑ v R (Rayleigh wave velocity), the dynamic stress strength factor K 2(t) →+0, and changes from positive into negative in the interval ( v R, β ). How v transit the forbidden of ( v R, β )? The divergence difficulty means K 2(t) →+∞ when v ↓ β . Here we introduce the concept of fractal and tunnel effect that exist everywhere in fault. The structure of all the faults is fractal with multiple cracks. The velocity of fault rupture is differentiate of the length of the fault respect to time, so the rupture velocity is also fractal. The tunnel effect means the dynamic rupture crosses over the interval of the cracks, and the coalescence of the intervals is slower than the propagation of disturbance. Suppose the area of earthquake nucleation is critical or sub critical propagation everywhere, the arriving of disturbance triggers or accelerates the propagation of cracks tip at once, and the observation system cannot distinguish the front of disturbance and the tip of fracture. Then the speed of disturbance may be identified as fracture velocity, and the phenomenon of TSVR appears, which is an apparent velocity. The real reason of apparent velocity is that the mathematics model of shear rupture is simplified of complex process originally. The dual character of rupture velocity means that the apparent velocity of fault and the real velocity of micro crack extending, which are different in physics, but are unified in rupture criterion. Introducing the above mentioned concept to the calculation of K 2 (t) , the difficulty of initialization can be overcome, and the integral equation of triggering the initialization of TSVR is given quantitatively. By solving this integral equation, the lower limit of TSVR is 1.105 3 β , not β , and the divergence difficulty is overcome. TSVR is unstable solution, and may degenerate to sub Rayleigh wave velocity rupture immediately where the non critical condition can be measured. The results of this paper show that the initialization and continuum depends on the condition of earthquake nucleation in seismogenic area.展开更多
Two-dimensional van der Waals(vdW)magnetic materials,characterized by their tunable magnetism,spin transport properties,and remarkable quantum effects,provide significant promise for the development of efficient,low-p...Two-dimensional van der Waals(vdW)magnetic materials,characterized by their tunable magnetism,spin transport properties,and remarkable quantum effects,provide significant promise for the development of efficient,low-power spintronic devices.Intriguingly,the rare earth tritelluride(RTe3)materials have attracted great attention due to their unique magnetic structure,exotic electronic properties,multiple charge density wave(CDW),and superconductivity under pressure.Here,we report the successful synthesis of high-quality DyTe_(3)single crystals using a self-flux method.DyTe_(3)shows an antiferromagnetic transition at 4.5 K and demonstrates the magnetic field-induced ferromagnetism.The high-quality DyTe_(3)single crystal demonstrates outstanding transport properties,featuring a high carrier mobility of approximately1.4×10^(4)cm^(2)·V^(-1)·s^(-1)and large linear magnetoresistance of 1300%.Furthermore,distinct Shubnikov-de Haas(SdH)oscillations are observed in DyTe_(3),revealing a small Fermi pocket and an effective mass of 0.24 me.Remarkably,the unconventional in-plane negative magnetoresistances appear along the a-axis below 2 T and c-axis until 9 T from 2 K to17 K,which are attributed to the complex helimagnetic structures caused by CDW coupling and weak single-ion anisotropy.Our findings offer a significant platform for understanding the complex magnetoresistance behavior and quantum transport effects in RTe3-type materials,holding great promise for advancing applications in electronic and spintronic devices.展开更多
The evolution of microstructure and texture in Mg-3Al-1Zn-1Ca alloy sheets subjected to in-plane shear(IPS)loading was investigated using experimental techniques and viscoplastic self-consistent(VPSC)modeling.The spec...The evolution of microstructure and texture in Mg-3Al-1Zn-1Ca alloy sheets subjected to in-plane shear(IPS)loading was investigated using experimental techniques and viscoplastic self-consistent(VPSC)modeling.The specimens were deformed under varying degrees of IPS strain(γ12=0.05,0.10,and 0.15)using a customized jig.Electron backscatter diffraction(EBSD)observations revealed profuse tensile twinning(TTW)even at an IPS strain of 0.05,with its intensity continuously increased as the IPS strain increased.The TTWs progressively engulfed parent grains with increasing shear strain,evolving into an unusual deformation twin morphology.Furthermore,VPSC model predictions confirmed basal slip as the dominant deformation mode at low IPS strains,transitioning to prismatic slip dominance at higher IPS strains.The activity of the TTW mode was significantly higher during the initial stages of IPS strain and saturated to lower values at higher strains.VPSC simulation results also indicated preferential shear accumulation on a single twin system,explaining the phenomenon of a single twin variant engulfing a parent grain.Additionally,the influence of individual slip and twin modes on texture evolution was evaluated through orientation tracking of representative grains at various shear strain increments using VPSC simulation.The simulation results quantitatively highlighted the activities of basal slip,prismatic slip,and tensile twinning,establishing a correlation between texture evolution and the underlying deformation mechanisms.展开更多
Exploring earth-abundant,highly active bifunctional electrocatalysts for efficient hydrogen and oxygen evolution is crucial for water splitting.However,due to their distinct free energies and conducting behaviors(elec...Exploring earth-abundant,highly active bifunctional electrocatalysts for efficient hydrogen and oxygen evolution is crucial for water splitting.However,due to their distinct free energies and conducting behaviors(electron/hole),balancing the catalytic efficiency between hydrogen and oxygen evolution remains challenging for achieving bifunctional electrocatalysts.Here,we report a locally-doped MoS_(2)monolayer with an in-plane heterostructure acting as a bifunctional electrocatalyst and apply it to the overall water splitting.In this heterostructure,the core region contains Mo/S vacancies,while the ring region was doped by Fe atoms(in two substitution configurations:1FeMo and 3FeMo-VS clusters)with a p-type conductive characteristic.Our micro-cell measurements,combined with density functional theory(DFT)calculations,reveal that the vacancies-rich core region presents remarkable hydrogen evolution reaction(HER)activity while the Fe-doped ring gives an excellent oxygen evolution reaction(OER)activity,thus forming an in-plane bifunctional electrocatalyst.Finally,as a proof-of-concept for overall water splitting,we constructed a full-cell configuration based on a locally-doped MoS_(2)monolayer,which achieved a cell voltage of 1.87 V at 10 mA·cm^(-2),demonstrating outstanding performance in strong acid electrolytes.Our work provides insight into the hetero-integration of bifunctional electrocatalysts at the atomic level,paving the way for designing transition metal dichalcogenide catalysts with activity-manipulated regions capable of multiple reactions.展开更多
The in-plane optical anisotropy(IPOA) of c-plane In Ga N/Ga N quantum disks(Qdisks) in nanowires grown on MoS_(2)/Mo and Ti/Mo substrates is investigated using reflectance difference spectroscopy(RDS) at room temperat...The in-plane optical anisotropy(IPOA) of c-plane In Ga N/Ga N quantum disks(Qdisks) in nanowires grown on MoS_(2)/Mo and Ti/Mo substrates is investigated using reflectance difference spectroscopy(RDS) at room temperature. A large IPOA related to defect or impurity states is observed. The IPOA of samples grown on MoS_(2)/Mo is approximately one order of magnitude larger than that of samples grown on Ti/Mo substrates. Numerical calculations based on the envelope function approximation have been performed to analyze the origin of the IPOA. It is found that the IPOA primarily results from the segregation of indium atoms in the In Ga N/Ga N Qdisks. This work highlights the significant influence of substrate materials on the IPOA of semiconductor heterostructures.展开更多
Demonstrated that analog of diffractive and refractive 3D optics in free space can be developed to manipulate surface waves such as surface plasmon polaritons (SPPs). It has been shown that an air-gap control of a flo...Demonstrated that analog of diffractive and refractive 3D optics in free space can be developed to manipulate surface waves such as surface plasmon polaritons (SPPs). It has been shown that an air-gap control of a floating dielectric block can generate the dynamic phase and amplitude modulation of the SPP transmission coefficient. Unlike conventional bulk optics, the nano-scale surface optics for SPP processing contains several unexpected and interesting features in addition to the physical features described. Dynamic plasmonic information processing on the nano-scale using air-gap control may be an effective mechanism for building a dynamic plasmonic information processing system.展开更多
The kagome superconductor CsV_(3)Sb_(5) with exotic electronic properties has attracted substantial research interest,and the interplay between the superconductivity and the charge-density wave is crucial for understa...The kagome superconductor CsV_(3)Sb_(5) with exotic electronic properties has attracted substantial research interest,and the interplay between the superconductivity and the charge-density wave is crucial for understanding its unusual electronic ground state.In this work,we performed resistivity and AC magnetic susceptibility measurements on CsV_(3)Sb_(5) single crystals uniaxially-strained along[100]and[110]directions.We find that the uniaxial-strain tuning effect of T_(c)(dT_(c)/dε)and T_(CDW)(dT_(CDW)/dε)are almost identical along these distinct high-symmetry directions.These findings suggest the in-plane uniaxial-strain-tuning of T_(c) and T_(CDW)in CsV_(3)Sb_(5) are dominated by associated c-axis strain,whereas the response to purely in-plane strains is likely small.展开更多
Current active and passive noise reduction methods heavily rely on factors such as material properties,structural design,and weight,with noise cancellation processes primarily focused on gaseous,liquid,and solid state...Current active and passive noise reduction methods heavily rely on factors such as material properties,structural design,and weight,with noise cancellation processes primarily focused on gaseous,liquid,and solid states.In this study,we propose a novel theoretical model for modulating incident noise using ionic acoustic waves generated by corona discharge in the plasma state.These ionic acoustic waves are produced through the combined effects of thermal pressure from plasma ions and electrostatic forces arising from charge separation.Plasma-acoustic wave modulation based on negative corona discharge alters the dielectric field within the ionization region by influencing the motion of charged ions and electrons,thereby affecting the acoustic wave propagation process.Specifically,the generated ionic acoustic waves interfere with incident noise waves,leading to noise reduction.By adjusting the applied voltage,electrode gap,and discharge position in a needle-plate discharge configuration,the frequency,phase,and amplitude of the ionic acoustic waves can be precisely controlled,thereby modifying the interference outcomes.Theoretical verification demonstrates that tailored ionic acoustic waves effectively cancel incident noise within the 1-1000 Hz and 1000-2000 Hz frequency ranges.This work confirms the robustness of plasma-based corona discharge for future acoustic wave modulation applications and provides a theoretical foundation for developing“plasma-state noise reduction”acoustic functional devices.展开更多
Strong seismic excitation and fault dislocation are likely to occur simultaneously in high-intensity seismic zones,causing severe damage to tunnels crossing active fault zones.This paper aims to develop a novel analyt...Strong seismic excitation and fault dislocation are likely to occur simultaneously in high-intensity seismic zones,causing severe damage to tunnels crossing active fault zones.This paper aims to develop a novel analytical solution to determine the longitudinal mechanical responses of tunnels subjected to the combined effects of seismic waves and strike-slip faulting.Adopting the elastic springbeam model,the seismic waves are modelled as shear horizontal(SH)waves and the fault dislocation follows an S-shaped pattern;the superposition principle for free-fielddisplacements caused by both effects is assumed.In addition,the transmission and reflectionof seismic waves at the fault-rock geological interface and the tangential contact conditions at the tunnel-rock interface are considered.The analytical model is validated against numerical simulations,confirmingits accuracy in calculating tunnel responses.Moreover,a parametric study is conducted to evaluate the impact of key factors,including fault displacement,fault zone width,fault dip angle,earthquake frequency,rock conditions,tunnel lining stiffness,and tangential contact conditions,on tunnel responses.Compared with each effect alone,the combined effects of seismic waves and strike-slip faulting significantlychange the tunnel deformation and internal forces,leading to increased tunnel responses,especially within the fault zone and near the fault-rock interfaces.Depending on specificparameters,tunnel responses can be classifiedinto seismic-dominated,faulting-dominated,and seismic-faulting coupled responses on the basis of the relative contributions of each effect.The proposed analytical solution can be applied to quickly predict the longitudinal mechanical behaviour of tunnels under such combined effects in engineering applications.展开更多
Offshore structures are constantly subjected to the complex forces of the marine environment,including wind,sea waves,currents,and seismic loadings.Among these,wind and sea wave forces persist throughout the structure...Offshore structures are constantly subjected to the complex forces of the marine environment,including wind,sea waves,currents,and seismic loadings.Among these,wind and sea wave forces persist throughout the structure’s lifetime.This study proposes a dynamic analysis approach that incorporates both time and frequency domain methods to investigate the structural responses of offshore structures under the combined effects of wind and wave forces.A wind wave-pier coupling dynamic model is first developed using a small-scale single pier,with corresponding dynamic equilibrium equations established.Fluctuating wind and sea waves are simulated using the weighted amplitude wave superposition(WAWS)method and linear superposition,respectively.Wind and wave load histories are then derived via Fourier transforms.The structural dynamic responses under different loading scenarios(wind only,wave only,and combined wind and wave)are analyzed using the Newmarkβmethod.Additionally,the effects of varying wind and wave parameters on structural responses are evaluated.The simulation results demonstrate that the structural responses to wind-wave coupling are smaller than the superimposed effects of wind and wave forces acting independently.When wind speeds are relatively low,wave forces dominate structural displacement and serve as the primary source of vibration.展开更多
The damage evolution of polycrystalline Al with helium(He)bubbles under strongly decaying shock waves is studied by molecular dynamics simulations.A new damage region is observed near the loading side of the sample,an...The damage evolution of polycrystalline Al with helium(He)bubbles under strongly decaying shock waves is studied by molecular dynamics simulations.A new damage region is observed near the loading side of the sample,and the evolution characteristics and underlying mechanisms are elucidated.The development of damage in the new damage region begins after complete unloading of the incident shock wave and is further enhanced when the tensile stress arrives later.The damage evolution is completely controlled by the expansion-merging of He bubbles,without nucleation–growth of voids.This new damage region can be divided into two sections,each of which exhibits a unique dominant mechanism.The damage in the section closer to the loading side is due to the reverse velocity gradient formed after complete unloading of the incident shock wave,depending on the rate of decrease and the amplitude of the initial peak pressure.A high initial peak pressure that can lead to melting of material near the loading side is a necessary condition for the formation of the new damage region,since a significant reverse velocity gradient can only be established if melting occurs.The dominant mechanism in the section distant from the loading side is the action of tensile stress,associated with the profile of the incident shock wave upon reaching the free surface,which determines the material phase near the free surface.Moreover,the presence of He bubbles is another critical factor for formation of the new damage region,which does not occur in pure Al samples.展开更多
Biochar and biochar composites are versatile materials that can be used in many applications.In this study,biochar was prepared from sawdust and combined with the yttrium iron garnet(YIG)nanocrystal to investigate the...Biochar and biochar composites are versatile materials that can be used in many applications.In this study,biochar was prepared from sawdust and combined with the yttrium iron garnet(YIG)nanocrystal to investigate the shielding effectiveness of the composite structure.Firstly,the effect of the pyrolysis temperature on the shielding effectiveness of biochar was investigated.Secondly,biochars combined with YIG nanocrystals with different contents and shielding effectiveness of the composites were investigated.The electromagnetic effectiveness of the samples was investigated within the X band(8-12 GHz).The findings indicate that biochar demonstrates enhanced absorption properties with elevated pyrolysis temperatures.Biochars demonstrated an approximate 40 d B shielding effectiveness,while YIG exhibited approximately 7 d B,corresponding to absorption at 8 GHz.However,the combination of biochar and YIG exhibited exceptional absorption,reaching 67.12 d B at 8 GHz.展开更多
Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at ...Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at three tunnels.The research focuses on both the temporal evolution and spatial propagation of airblasts.Temporal analysis,including peak overpressure(POp),positive duration(PD),and Fourier main frequency(MF),emphasizes the relationship between airblast characteristics,blasting delays,and rock grade.It shows that airblast bandwidths are typically in the range of 3e200 Hz,with noise levels exceeding 130 dB,which is comparable to jet engines and rocket launch.Spatial propagation analysis reveals the impact of tunnel space on airblast propagation.Although POp and PD typically decrease with distance inside the tunnel,wave superposition can cause increased overpressure and prolonged durations at far-field distances(above 60 m kg^(-1/3)).Outside the tunnel,sound radiation was influenced by azimuth and was basically determined by sound power d an often-overlooked factor.To address the anisotropic propagation of airblasts,a predictive model was proposed for external noise levels,considering variables like distance,azimuth angle,initial sound power,and wave expansion.Validated by tests,this model successfully unifies data from three studies,helping to explain and predict airblast disturbances near tunnels.展开更多
Most existing path planning approaches rely on discrete expansions or localized heuristics that can lead to extended re-planning,inefficient detours,and limited adaptability to complex obstacle distributions.These iss...Most existing path planning approaches rely on discrete expansions or localized heuristics that can lead to extended re-planning,inefficient detours,and limited adaptability to complex obstacle distributions.These issues are particularly pronounced when navigating cluttered or large-scale environments that demand both global coverage and smooth trajectory generation.To address these challenges,this paper proposes a Wave Water Simulator(WWS)algorithm,leveraging a physically motivated wave equation to achieve inherently smooth,globally consistent path planning.In WWS,wavefront expansions naturally identify safe corridors while seamlessly avoiding local minima,and selective corridor focusing reduces computational overhead in large or dense maps.Comprehensive simulations and real-world validations-encompassing both indoor and outdoor scenarios-demonstrate that WWS reduces path length by 2%-13%compared to conventional methods,while preserving gentle curvature and robust obstacle clearance.Furthermore,WWS requires minimal parameter tuning across diverse domains,underscoring its broad applicability to warehouse robotics,field operations,and autonomous service vehicles.These findings confirm that the proposed wave-based framework not only bridges the gap between local heuristics and global coverage but also sets a promising direction for future extensions toward dynamic obstacle scenarios and multi-agent coordination.展开更多
In manganese electrolysis,electrochemical oscillations and manganese dendrite growth are typical nonlinear phenomena critical for energy consumption reduction.Nonetheless,existing research lacks a deep understanding o...In manganese electrolysis,electrochemical oscillations and manganese dendrite growth are typical nonlinear phenomena critical for energy consumption reduction.Nonetheless,existing research lacks a deep understanding of their underlying mechanisms.In this study,we systematically explored the evolution of anode electrochemical oscillations during manganese electrolysis and designed a square wave circuit to effectively suppress oscillations and dendrite growth while reducing energy consumption.A novel four-dimensional differential equation was introduced to explore the internal dynamic mechanisms of typical nonlinear behaviors.The experimental results showed that while the evolutionary patterns of current and potential oscillation signals were consistent,their waveform directions were opposite.The square wave current effectively suppressed both electrochemical oscillations and the growth of manganese dendrites.Furthermore,compared to direct current electrolysis,the square wave current improved the current efficiency by 3.6%and reduced the energy consumption by 0.32 kW·h·kg^(−1).展开更多
Studies of wave-current interactions are vital for the safe design of structures.Regular waves in the presence of uniform,linear shear,and quadratic shear currents are explored by the High-Level Green-Naghdi model in ...Studies of wave-current interactions are vital for the safe design of structures.Regular waves in the presence of uniform,linear shear,and quadratic shear currents are explored by the High-Level Green-Naghdi model in this paper.The five-point central difference method is used for spatial discretization,and the fourth-order Adams predictor-corrector scheme is employed for marching in time.The domain-decomposition method is applied for the wave-current generation and absorption.The effects of currents on the wave profile and velocity field are examined under two conditions:the same velocity of currents at the still-water level and the constant flow volume of currents.Wave profiles and velocity fields demonstrate substantial differences in three types of currents owing to the diverse vertical distribution of current velocity and vorticity.Then,loads on small-scale vertical cylinders subjected to regular waves and three types of background currents with the same flow volume are investigated.The maximum load intensity and load fluctuation amplitude in uniform,linear shear,and quadratic shear currents increase sequentially.The stretched superposition method overestimates the maximum load intensity and load fluctuation amplitude in opposing currents and underestimates these values in following currents.The stretched superposition method obtains a poor approximation for strong nonlinear waves,particularly in the case of the opposing quadratic shear current.展开更多
This study investigates the relationship between atmospheric stratification (i.e., static stability given by N^(2)) and the vertical energy transfer of stationary planetary waves, and further illustrates the underlyin...This study investigates the relationship between atmospheric stratification (i.e., static stability given by N^(2)) and the vertical energy transfer of stationary planetary waves, and further illustrates the underlying physical mechanism. Specifically, for the simplified case of constant stratospheric N^(2), the refractive index square of planetary waves has a theoretical tendency to increase first and then decrease with an increased N^(2), whereas the group velocity weakens. Mechanistically, this behavior can be understood as an intensified suppression of vertical isentropic surface displacement caused by meridional heat transport of planetary waves under strong N^(2) conditions. Observational analysis corroborates this finding, demonstrating a reduction in the vertical-propagation velocity of waves with increased N^(2). A linear, quasi- geostrophic, mid-latitude beta-plane model with a constant background westerly wind and a prescribed N^(2) applicable to the stratosphere is used to obtain analytic solutions. In this model, the planetary waves are initiated by steady energy influx from the lower boundary. The analysis indicates that under strong N^(2) conditions, the amplitude of planetary waves can be sufficiently increased by the effective energy convergence due to the slowing vertical energy transfer, resulting in a streamfunction response in this model that contains more energy. For N^(2) with a quasi-linear vertical variation, the results bear a resemblance to the constant case, except that the wave amplitude and oscillating frequency show some vertical variations.展开更多
基金the National Natural Science Foundation of China(50478014)the National 973 Program(2007CB714200)the Beijing Natural Science Foundation(8061003).
文摘A 1D finite element method in time domain is developed in this paper and applied to calculate in-plane wave motions of free field exited by SV or P wave oblique incidence in an elastic layered half-space. First, the layered half-space is discretized on the basis of the propagation characteristic of elastic wave according to the Snell law. Then, the finite element method with lumped mass and the central difference method are incorporated to establish 2D wave motion equations, which can be transformed into 1D equations by discretization principle and explicit finite element method. By solving the 1D equations, the displacements of nodes in any vertical line can be obtained, and the wave motions in layered half-space are finally determined based on the characteristic of traveling wave. Both the theoretical analysis and the numerical results demonstrate that the proposed method has high accuracy and good stability.
基金The project sponsored by the Earthquake Science Foundation under Contract No. 90141
文摘The analysis method of lattice dynamics in classical physics is extended to study the properties of in-plane wave motion in the hybrid-mass finite element model in this paper. The dispersion equations of P and SV waves in the discrete model are first obtained by means of separating the characteristic equation of the motion equation, and then used to analyse the properties of P-and SV-homogeneous, inhomogeneous waves and other types of motion in the model. The dispersion characters, cut-off frequencies of P and SV waves, the polarization drift and appendent anisotropic property of wave motion caused by the discretization are finally discussed.
基金supported by the National Natural Science Foundation of China(51178037,10632020)the 973 State Key Development Program for Basic Research of China(2010CB732104)
文摘In this paper, a method based on the Dirichlet- to-Neumann map is developed for bandgap calculation of mixed in-plane waves propagating in 2D phononic crystals with square and triangular lattices. The method expresses the scattered fields in a unit cell as the cylindrical wave expansions and imposes the Bloch condition on the boundary of the unit cell. The Dirichlet-to-Neumann （DtN） map is applied to obtain a linear eigenvalue equation, from which the Bloch wave vectors along the irreducible Brillouin zone are calculated for a given frequency. Compared with other methods, the present method is memory-saving and time-saving. It can yield accurate results with fast convergence for various material combinations including those with large acoustic mismatch without extra computational cost. The method is also efficient for mixed fluid-solid systems because it considers the different wave modes in the fluid and solid as well as the proper fluid-solid interface condition.
文摘Transient S wave velocity rupture (TSVR) means the velocity of fault rupture propagation is between S wave velocity α and P wave velocity β . Its existing in the rupture of in plane ( i.e . strike slip) fault has been proved, but in 2 dimensional classical model, there are two difficulties in transient S wave velocity rupture, i.e ., initialization difficulty and divergence difficulty in interpreting the realization of TSVR. The initialization difficulty means, when v ↑ v R (Rayleigh wave velocity), the dynamic stress strength factor K 2(t) →+0, and changes from positive into negative in the interval ( v R, β ). How v transit the forbidden of ( v R, β )? The divergence difficulty means K 2(t) →+∞ when v ↓ β . Here we introduce the concept of fractal and tunnel effect that exist everywhere in fault. The structure of all the faults is fractal with multiple cracks. The velocity of fault rupture is differentiate of the length of the fault respect to time, so the rupture velocity is also fractal. The tunnel effect means the dynamic rupture crosses over the interval of the cracks, and the coalescence of the intervals is slower than the propagation of disturbance. Suppose the area of earthquake nucleation is critical or sub critical propagation everywhere, the arriving of disturbance triggers or accelerates the propagation of cracks tip at once, and the observation system cannot distinguish the front of disturbance and the tip of fracture. Then the speed of disturbance may be identified as fracture velocity, and the phenomenon of TSVR appears, which is an apparent velocity. The real reason of apparent velocity is that the mathematics model of shear rupture is simplified of complex process originally. The dual character of rupture velocity means that the apparent velocity of fault and the real velocity of micro crack extending, which are different in physics, but are unified in rupture criterion. Introducing the above mentioned concept to the calculation of K 2 (t) , the difficulty of initialization can be overcome, and the integral equation of triggering the initialization of TSVR is given quantitatively. By solving this integral equation, the lower limit of TSVR is 1.105 3 β , not β , and the divergence difficulty is overcome. TSVR is unstable solution, and may degenerate to sub Rayleigh wave velocity rupture immediately where the non critical condition can be measured. The results of this paper show that the initialization and continuum depends on the condition of earthquake nucleation in seismogenic area.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62488201 and 1240041502)the Ministry of Science and Technology of China(Grant No.2022YFA1204100)+1 种基金the Chinese Academy of Sciences(Grant No.XDB33030100)the Innovation Program of Quantum Science and Technology(Grant No.2021ZD0302700)。
文摘Two-dimensional van der Waals(vdW)magnetic materials,characterized by their tunable magnetism,spin transport properties,and remarkable quantum effects,provide significant promise for the development of efficient,low-power spintronic devices.Intriguingly,the rare earth tritelluride(RTe3)materials have attracted great attention due to their unique magnetic structure,exotic electronic properties,multiple charge density wave(CDW),and superconductivity under pressure.Here,we report the successful synthesis of high-quality DyTe_(3)single crystals using a self-flux method.DyTe_(3)shows an antiferromagnetic transition at 4.5 K and demonstrates the magnetic field-induced ferromagnetism.The high-quality DyTe_(3)single crystal demonstrates outstanding transport properties,featuring a high carrier mobility of approximately1.4×10^(4)cm^(2)·V^(-1)·s^(-1)and large linear magnetoresistance of 1300%.Furthermore,distinct Shubnikov-de Haas(SdH)oscillations are observed in DyTe_(3),revealing a small Fermi pocket and an effective mass of 0.24 me.Remarkably,the unconventional in-plane negative magnetoresistances appear along the a-axis below 2 T and c-axis until 9 T from 2 K to17 K,which are attributed to the complex helimagnetic structures caused by CDW coupling and weak single-ion anisotropy.Our findings offer a significant platform for understanding the complex magnetoresistance behavior and quantum transport effects in RTe3-type materials,holding great promise for advancing applications in electronic and spintronic devices.
文摘The evolution of microstructure and texture in Mg-3Al-1Zn-1Ca alloy sheets subjected to in-plane shear(IPS)loading was investigated using experimental techniques and viscoplastic self-consistent(VPSC)modeling.The specimens were deformed under varying degrees of IPS strain(γ12=0.05,0.10,and 0.15)using a customized jig.Electron backscatter diffraction(EBSD)observations revealed profuse tensile twinning(TTW)even at an IPS strain of 0.05,with its intensity continuously increased as the IPS strain increased.The TTWs progressively engulfed parent grains with increasing shear strain,evolving into an unusual deformation twin morphology.Furthermore,VPSC model predictions confirmed basal slip as the dominant deformation mode at low IPS strains,transitioning to prismatic slip dominance at higher IPS strains.The activity of the TTW mode was significantly higher during the initial stages of IPS strain and saturated to lower values at higher strains.VPSC simulation results also indicated preferential shear accumulation on a single twin system,explaining the phenomenon of a single twin variant engulfing a parent grain.Additionally,the influence of individual slip and twin modes on texture evolution was evaluated through orientation tracking of representative grains at various shear strain increments using VPSC simulation.The simulation results quantitatively highlighted the activities of basal slip,prismatic slip,and tensile twinning,establishing a correlation between texture evolution and the underlying deformation mechanisms.
基金supported by the National Natural Science Foundation of China(Nos.22175060 and 22376062)JSPS Grant-in-Aid for Scientific Research(Nos.JP21H05235,JP22H05478 and JP22F22358)+1 种基金China Postdoctoral Science Foundation(No.2022M722867)the Key Research Project of Higher Education Institutions in Henan Province(No.23A530001).
文摘Exploring earth-abundant,highly active bifunctional electrocatalysts for efficient hydrogen and oxygen evolution is crucial for water splitting.However,due to their distinct free energies and conducting behaviors(electron/hole),balancing the catalytic efficiency between hydrogen and oxygen evolution remains challenging for achieving bifunctional electrocatalysts.Here,we report a locally-doped MoS_(2)monolayer with an in-plane heterostructure acting as a bifunctional electrocatalyst and apply it to the overall water splitting.In this heterostructure,the core region contains Mo/S vacancies,while the ring region was doped by Fe atoms(in two substitution configurations:1FeMo and 3FeMo-VS clusters)with a p-type conductive characteristic.Our micro-cell measurements,combined with density functional theory(DFT)calculations,reveal that the vacancies-rich core region presents remarkable hydrogen evolution reaction(HER)activity while the Fe-doped ring gives an excellent oxygen evolution reaction(OER)activity,thus forming an in-plane bifunctional electrocatalyst.Finally,as a proof-of-concept for overall water splitting,we constructed a full-cell configuration based on a locally-doped MoS_(2)monolayer,which achieved a cell voltage of 1.87 V at 10 mA·cm^(-2),demonstrating outstanding performance in strong acid electrolytes.Our work provides insight into the hetero-integration of bifunctional electrocatalysts at the atomic level,paving the way for designing transition metal dichalcogenide catalysts with activity-manipulated regions capable of multiple reactions.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 62074036, 61674038, and 11574302)Foreign Cooperation Project of Fujian Province (Grant No. 2023I0005)+2 种基金Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics (Grant No. KF202108)the National Key Research and Development Program (Grant No. 2016YFB0402303)the Foundation of Fujian Provincial Department of Industry and Information Technology of China (Grant No. 82318075)。
文摘The in-plane optical anisotropy(IPOA) of c-plane In Ga N/Ga N quantum disks(Qdisks) in nanowires grown on MoS_(2)/Mo and Ti/Mo substrates is investigated using reflectance difference spectroscopy(RDS) at room temperature. A large IPOA related to defect or impurity states is observed. The IPOA of samples grown on MoS_(2)/Mo is approximately one order of magnitude larger than that of samples grown on Ti/Mo substrates. Numerical calculations based on the envelope function approximation have been performed to analyze the origin of the IPOA. It is found that the IPOA primarily results from the segregation of indium atoms in the In Ga N/Ga N Qdisks. This work highlights the significant influence of substrate materials on the IPOA of semiconductor heterostructures.
文摘Demonstrated that analog of diffractive and refractive 3D optics in free space can be developed to manipulate surface waves such as surface plasmon polaritons (SPPs). It has been shown that an air-gap control of a floating dielectric block can generate the dynamic phase and amplitude modulation of the SPP transmission coefficient. Unlike conventional bulk optics, the nano-scale surface optics for SPP processing contains several unexpected and interesting features in addition to the physical features described. Dynamic plasmonic information processing on the nano-scale using air-gap control may be an effective mechanism for building a dynamic plasmonic information processing system.
基金supported by the National Key Projects for Research and Development of China (Grant No.2021YFA1400400)the National Natural Science Foundation of China (Grant Nos.12174029 and 11922402)+3 种基金supported by the National Key Research and Development Program of China (Grant No.2022YFA1402200)the Pioneer and Leading Goose Research and Development Program of Zhejiang Province,China (Grant No.2022SDX-HDX0005)the Key Research and Development Program of Zhejiang Province,China (Grant No.2021C01002)the National Natural Science Foundation of China (Grant No.12274363)。
文摘The kagome superconductor CsV_(3)Sb_(5) with exotic electronic properties has attracted substantial research interest,and the interplay between the superconductivity and the charge-density wave is crucial for understanding its unusual electronic ground state.In this work,we performed resistivity and AC magnetic susceptibility measurements on CsV_(3)Sb_(5) single crystals uniaxially-strained along[100]and[110]directions.We find that the uniaxial-strain tuning effect of T_(c)(dT_(c)/dε)and T_(CDW)(dT_(CDW)/dε)are almost identical along these distinct high-symmetry directions.These findings suggest the in-plane uniaxial-strain-tuning of T_(c) and T_(CDW)in CsV_(3)Sb_(5) are dominated by associated c-axis strain,whereas the response to purely in-plane strains is likely small.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFC2803000)the National Natural Science Foundation of China(Grants Nos.U21B200312,11704314,52171323)the China Postdoctoral Science Foundation(Grant No.2018M631194)。
文摘Current active and passive noise reduction methods heavily rely on factors such as material properties,structural design,and weight,with noise cancellation processes primarily focused on gaseous,liquid,and solid states.In this study,we propose a novel theoretical model for modulating incident noise using ionic acoustic waves generated by corona discharge in the plasma state.These ionic acoustic waves are produced through the combined effects of thermal pressure from plasma ions and electrostatic forces arising from charge separation.Plasma-acoustic wave modulation based on negative corona discharge alters the dielectric field within the ionization region by influencing the motion of charged ions and electrons,thereby affecting the acoustic wave propagation process.Specifically,the generated ionic acoustic waves interfere with incident noise waves,leading to noise reduction.By adjusting the applied voltage,electrode gap,and discharge position in a needle-plate discharge configuration,the frequency,phase,and amplitude of the ionic acoustic waves can be precisely controlled,thereby modifying the interference outcomes.Theoretical verification demonstrates that tailored ionic acoustic waves effectively cancel incident noise within the 1-1000 Hz and 1000-2000 Hz frequency ranges.This work confirms the robustness of plasma-based corona discharge for future acoustic wave modulation applications and provides a theoretical foundation for developing“plasma-state noise reduction”acoustic functional devices.
基金supported by the National Natural Science Foundation of China(No.41941018)Shanghai Gaofeng Discipline Construction Funding.
文摘Strong seismic excitation and fault dislocation are likely to occur simultaneously in high-intensity seismic zones,causing severe damage to tunnels crossing active fault zones.This paper aims to develop a novel analytical solution to determine the longitudinal mechanical responses of tunnels subjected to the combined effects of seismic waves and strike-slip faulting.Adopting the elastic springbeam model,the seismic waves are modelled as shear horizontal(SH)waves and the fault dislocation follows an S-shaped pattern;the superposition principle for free-fielddisplacements caused by both effects is assumed.In addition,the transmission and reflectionof seismic waves at the fault-rock geological interface and the tangential contact conditions at the tunnel-rock interface are considered.The analytical model is validated against numerical simulations,confirmingits accuracy in calculating tunnel responses.Moreover,a parametric study is conducted to evaluate the impact of key factors,including fault displacement,fault zone width,fault dip angle,earthquake frequency,rock conditions,tunnel lining stiffness,and tangential contact conditions,on tunnel responses.Compared with each effect alone,the combined effects of seismic waves and strike-slip faulting significantlychange the tunnel deformation and internal forces,leading to increased tunnel responses,especially within the fault zone and near the fault-rock interfaces.Depending on specificparameters,tunnel responses can be classifiedinto seismic-dominated,faulting-dominated,and seismic-faulting coupled responses on the basis of the relative contributions of each effect.The proposed analytical solution can be applied to quickly predict the longitudinal mechanical behaviour of tunnels under such combined effects in engineering applications.
基金Project(2022YFB2302700)supported by the National Key Research and Development Program of China。
文摘Offshore structures are constantly subjected to the complex forces of the marine environment,including wind,sea waves,currents,and seismic loadings.Among these,wind and sea wave forces persist throughout the structure’s lifetime.This study proposes a dynamic analysis approach that incorporates both time and frequency domain methods to investigate the structural responses of offshore structures under the combined effects of wind and wave forces.A wind wave-pier coupling dynamic model is first developed using a small-scale single pier,with corresponding dynamic equilibrium equations established.Fluctuating wind and sea waves are simulated using the weighted amplitude wave superposition(WAWS)method and linear superposition,respectively.Wind and wave load histories are then derived via Fourier transforms.The structural dynamic responses under different loading scenarios(wind only,wave only,and combined wind and wave)are analyzed using the Newmarkβmethod.Additionally,the effects of varying wind and wave parameters on structural responses are evaluated.The simulation results demonstrate that the structural responses to wind-wave coupling are smaller than the superimposed effects of wind and wave forces acting independently.When wind speeds are relatively low,wave forces dominate structural displacement and serve as the primary source of vibration.
基金supported by the National Natural Science Foundation of China(Grant No.12172063).
文摘The damage evolution of polycrystalline Al with helium(He)bubbles under strongly decaying shock waves is studied by molecular dynamics simulations.A new damage region is observed near the loading side of the sample,and the evolution characteristics and underlying mechanisms are elucidated.The development of damage in the new damage region begins after complete unloading of the incident shock wave and is further enhanced when the tensile stress arrives later.The damage evolution is completely controlled by the expansion-merging of He bubbles,without nucleation–growth of voids.This new damage region can be divided into two sections,each of which exhibits a unique dominant mechanism.The damage in the section closer to the loading side is due to the reverse velocity gradient formed after complete unloading of the incident shock wave,depending on the rate of decrease and the amplitude of the initial peak pressure.A high initial peak pressure that can lead to melting of material near the loading side is a necessary condition for the formation of the new damage region,since a significant reverse velocity gradient can only be established if melting occurs.The dominant mechanism in the section distant from the loading side is the action of tensile stress,associated with the profile of the incident shock wave upon reaching the free surface,which determines the material phase near the free surface.Moreover,the presence of He bubbles is another critical factor for formation of the new damage region,which does not occur in pure Al samples.
基金support provided by the Center for Fabrication and Application of Electronic Materials at Dokuz Eylül University,Türkiye。
文摘Biochar and biochar composites are versatile materials that can be used in many applications.In this study,biochar was prepared from sawdust and combined with the yttrium iron garnet(YIG)nanocrystal to investigate the shielding effectiveness of the composite structure.Firstly,the effect of the pyrolysis temperature on the shielding effectiveness of biochar was investigated.Secondly,biochars combined with YIG nanocrystals with different contents and shielding effectiveness of the composites were investigated.The electromagnetic effectiveness of the samples was investigated within the X band(8-12 GHz).The findings indicate that biochar demonstrates enhanced absorption properties with elevated pyrolysis temperatures.Biochars demonstrated an approximate 40 d B shielding effectiveness,while YIG exhibited approximately 7 d B,corresponding to absorption at 8 GHz.However,the combination of biochar and YIG exhibited exceptional absorption,reaching 67.12 d B at 8 GHz.
基金supported by the Shenzhen Stability Support Plan(Grant No.20231122095154003)National Natural Science Foundation of China(Grant Nos.51978671 and 52422807).
文摘Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at three tunnels.The research focuses on both the temporal evolution and spatial propagation of airblasts.Temporal analysis,including peak overpressure(POp),positive duration(PD),and Fourier main frequency(MF),emphasizes the relationship between airblast characteristics,blasting delays,and rock grade.It shows that airblast bandwidths are typically in the range of 3e200 Hz,with noise levels exceeding 130 dB,which is comparable to jet engines and rocket launch.Spatial propagation analysis reveals the impact of tunnel space on airblast propagation.Although POp and PD typically decrease with distance inside the tunnel,wave superposition can cause increased overpressure and prolonged durations at far-field distances(above 60 m kg^(-1/3)).Outside the tunnel,sound radiation was influenced by azimuth and was basically determined by sound power d an often-overlooked factor.To address the anisotropic propagation of airblasts,a predictive model was proposed for external noise levels,considering variables like distance,azimuth angle,initial sound power,and wave expansion.Validated by tests,this model successfully unifies data from three studies,helping to explain and predict airblast disturbances near tunnels.
文摘Most existing path planning approaches rely on discrete expansions or localized heuristics that can lead to extended re-planning,inefficient detours,and limited adaptability to complex obstacle distributions.These issues are particularly pronounced when navigating cluttered or large-scale environments that demand both global coverage and smooth trajectory generation.To address these challenges,this paper proposes a Wave Water Simulator(WWS)algorithm,leveraging a physically motivated wave equation to achieve inherently smooth,globally consistent path planning.In WWS,wavefront expansions naturally identify safe corridors while seamlessly avoiding local minima,and selective corridor focusing reduces computational overhead in large or dense maps.Comprehensive simulations and real-world validations-encompassing both indoor and outdoor scenarios-demonstrate that WWS reduces path length by 2%-13%compared to conventional methods,while preserving gentle curvature and robust obstacle clearance.Furthermore,WWS requires minimal parameter tuning across diverse domains,underscoring its broad applicability to warehouse robotics,field operations,and autonomous service vehicles.These findings confirm that the proposed wave-based framework not only bridges the gap between local heuristics and global coverage but also sets a promising direction for future extensions toward dynamic obstacle scenarios and multi-agent coordination.
基金support from the Fundamental Research Funds for the Central Universities(2022CDJQY-005,2024CDJXY010)the Guangxi Science and Technology Program(AB24010229)is greatly acknowledged.
文摘In manganese electrolysis,electrochemical oscillations and manganese dendrite growth are typical nonlinear phenomena critical for energy consumption reduction.Nonetheless,existing research lacks a deep understanding of their underlying mechanisms.In this study,we systematically explored the evolution of anode electrochemical oscillations during manganese electrolysis and designed a square wave circuit to effectively suppress oscillations and dendrite growth while reducing energy consumption.A novel four-dimensional differential equation was introduced to explore the internal dynamic mechanisms of typical nonlinear behaviors.The experimental results showed that while the evolutionary patterns of current and potential oscillation signals were consistent,their waveform directions were opposite.The square wave current effectively suppressed both electrochemical oscillations and the growth of manganese dendrites.Furthermore,compared to direct current electrolysis,the square wave current improved the current efficiency by 3.6%and reduced the energy consumption by 0.32 kW·h·kg^(−1).
基金Supported by the Development and Application Project of Ship CAE Software.
文摘Studies of wave-current interactions are vital for the safe design of structures.Regular waves in the presence of uniform,linear shear,and quadratic shear currents are explored by the High-Level Green-Naghdi model in this paper.The five-point central difference method is used for spatial discretization,and the fourth-order Adams predictor-corrector scheme is employed for marching in time.The domain-decomposition method is applied for the wave-current generation and absorption.The effects of currents on the wave profile and velocity field are examined under two conditions:the same velocity of currents at the still-water level and the constant flow volume of currents.Wave profiles and velocity fields demonstrate substantial differences in three types of currents owing to the diverse vertical distribution of current velocity and vorticity.Then,loads on small-scale vertical cylinders subjected to regular waves and three types of background currents with the same flow volume are investigated.The maximum load intensity and load fluctuation amplitude in uniform,linear shear,and quadratic shear currents increase sequentially.The stretched superposition method overestimates the maximum load intensity and load fluctuation amplitude in opposing currents and underestimates these values in following currents.The stretched superposition method obtains a poor approximation for strong nonlinear waves,particularly in the case of the opposing quadratic shear current.
基金supported by the National Natural Science Foundation of China(Grant No.42261134532,42405059,and U2342212)。
文摘This study investigates the relationship between atmospheric stratification (i.e., static stability given by N^(2)) and the vertical energy transfer of stationary planetary waves, and further illustrates the underlying physical mechanism. Specifically, for the simplified case of constant stratospheric N^(2), the refractive index square of planetary waves has a theoretical tendency to increase first and then decrease with an increased N^(2), whereas the group velocity weakens. Mechanistically, this behavior can be understood as an intensified suppression of vertical isentropic surface displacement caused by meridional heat transport of planetary waves under strong N^(2) conditions. Observational analysis corroborates this finding, demonstrating a reduction in the vertical-propagation velocity of waves with increased N^(2). A linear, quasi- geostrophic, mid-latitude beta-plane model with a constant background westerly wind and a prescribed N^(2) applicable to the stratosphere is used to obtain analytic solutions. In this model, the planetary waves are initiated by steady energy influx from the lower boundary. The analysis indicates that under strong N^(2) conditions, the amplitude of planetary waves can be sufficiently increased by the effective energy convergence due to the slowing vertical energy transfer, resulting in a streamfunction response in this model that contains more energy. For N^(2) with a quasi-linear vertical variation, the results bear a resemblance to the constant case, except that the wave amplitude and oscillating frequency show some vertical variations.
