A new model of periodic structure is proposed and analyzed.This structure is composed of an inner fluid-conveying pipe with periodic material arrangement carrying periodic arrays of outer cantilever pipes.The generali...A new model of periodic structure is proposed and analyzed.This structure is composed of an inner fluid-conveying pipe with periodic material arrangement carrying periodic arrays of outer cantilever pipes.The generalized differential quadrature rule(GDQR)method combined with the Bloch theorem is used to calculate the vibration band gaps of the structure.Results are verified by the forced vibration responses obtained using the GDQR method.Results indicate that the first two band gaps of the fluid-conveying pipe with periodic material arrangement can get close to each other and move to low frequency regions by changing the length of cantilever pipes.For high fluid velocity values in which the first band gap starts from zero frequency,since the second band is very close to the first band,this periodic structure can be used for vibration reduction over a wide band gap starting from zero frequency.Based on these results,it can be concluded that instead of increasing the total size of the periodic structure,these periodic arrays of cantilever pipes can be implemented to create a wide ultra-low-frequency band gap.Finally,verification of the GDQR method shows that it can be used as a precise numerical method for vibration analysis of the structures such as fluid-conveying pipes and moving belts.展开更多
This study aims to discuss the propagation characteristics of seismic Lamb wave and surface wave in a new radial gradient supercell seismic metamaterial(RGSSM).Different from the traditional seismic metamaterials with...This study aims to discuss the propagation characteristics of seismic Lamb wave and surface wave in a new radial gradient supercell seismic metamaterial(RGSSM).Different from the traditional seismic metamaterials with simple unit cells,the RGSSM consists of the supercells arranged periodically along the radial direction,and these supercells are composed of five kinds of unit cells with gradient filling rates.The dispersion curve and attenuation spectrum of the Lamb wave in RGSSM are studied with the finite element method combined with the supercell technology,generating a very low-frequency ultra-wide bandgap of 3.98-20 Hz,and a forbidden band generated by the localized modes forms multi-harmonic oscillators inside the supercell.Furthermore,it is found that the Young’s modulus of the soil is more sensitive to the effect of bandgap.In terms of surface wave,the RGSSM can produce rapid attenuation in the low frequency range of 5.2-8.5 Hz.Finally,a 3D model is designed to demonstrate the shielding performance of RGSSM against the seismic surface wave.The proposed RGSSM provides a new idea for the seismic isolation of ultra-wide and low-frequency seismic waves.展开更多
Ultra-low-frequency(ULF) waves are ubiquitous in terrestrial and planetary environments, playing a crucial role in energy transfer and dissipation through wave–particle interactions within space plasmas. By performin...Ultra-low-frequency(ULF) waves are ubiquitous in terrestrial and planetary environments, playing a crucial role in energy transfer and dissipation through wave–particle interactions within space plasmas. By performing a detailed event study in terms of particle distribution maps and wave–particle variable correlation maps, we report that ULF waves observed by the Mars Atmosphere and Volatile EvolutioN(MAVEN) spacecraft in the Martian foreshock can effectively modulate the suprathermal electron fluxes by the magnetic field fluctuations. In particular, the variations in electron fluxes at energies of ~10–100 eV are significant in the perpendicular direction, showing good relationships with changes in the wave field strength characterized by a correlation coefficient ~0.8. These findings demonstrate the generality of interactions of ULF waves with electrons, even at these low energies, highlighting the importance of such processes throughout the heliosphere.展开更多
Nonlinear Rossby waves are used to describe typical wave phenomena in large-scale atmosphere andocean.Owing to the nonlinearity of the involved problems,the weakly nonlinear method,ie the derivative ex-pansion method,...Nonlinear Rossby waves are used to describe typical wave phenomena in large-scale atmosphere andocean.Owing to the nonlinearity of the involved problems,the weakly nonlinear method,ie the derivative ex-pansion method,was mainly used to investigate Rossby waves under the combined effects of the generalizedβ-effect and the basic flow effect.The derivative expansion method has the advantage of capturing the multi-scalecharacteristics of wave processes simultaneously.In the case where the perturbation expansion is independentof secular terms,the nonlinear equations describing the amplitude evolution of nonlinear waves were derived,such as the Korteweg-de Vries equation,the Boussinesq equation and Zakharov-Kuznetsov equation.Both quali-tative and quantitative analyses indicate that the generalizedβ-effect is the key factor inducing the evolution ofRossby solitary waves.展开更多
To address the complex seismic response of long tunnels longitudinally crossing heterogeneous geological formations,this study proposes a three-dimensional SV-wave oblique-incidence input method that accounts for the ...To address the complex seismic response of long tunnels longitudinally crossing heterogeneous geological formations,this study proposes a three-dimensional SV-wave oblique-incidence input method that accounts for the initial disturbance of the wave field induced by geological heterogeneity.The method transforms equivalent twodimensional free-field responses into equivalent nodal forces applied at the boundaries of a 3D numerical model.A longitudinally heterogeneous“hard-soft-hard”site and tunnel system is established,in which the surrounding rock is modeled using the Mohr-Coulomb constitutive law,while the concrete lining is described by the concrete damaged plasticity model.The deformation patterns and failure mechanisms of the site-tunnel system under SV-wave excitation are systematically investigated.The results indicate that seismic damage under SV-wave loading is mainly concentrated in the soft-rock region.Failure of the soft surrounding rock induces pronounced sliding of the overlying hard rock,and the tunnel suffers severe damage due to the combined effects of soft-rock failure and strong ground shaking.Parametric analyses further show that smaller impedance ratios,larger soft-rock widths,and larger incidence angles significantly intensify the seismic response of the tunnel.The findings of this study provide valuable insights for the seismic design of tunnels crossing longitudinally heterogeneous geological formations.展开更多
Based on the theory of wave dynamics,this study systematically derives the steady-state analytical solution for the scattering of plane SV-waves by composite lined tunnels in an infinite space using the wave function ...Based on the theory of wave dynamics,this study systematically derives the steady-state analytical solution for the scattering of plane SV-waves by composite lined tunnels in an infinite space using the wave function expansion method.On this basis,a theoretical calculation model for circular composite linings under blast loading is established.Based on the steady-state analytical solution,theδ(x)-function and the Heaviside step function are introduced to construct the Duhamel integral,transforming the transient wave problem into an integral form.By further incorporating the Fourier integral transform,an analytical solution for the transient response around a composite lining tunnel subjected to a plane blast SV wave is ultimately derived.The computational results of this study are subsequently validated against those reported in existing literature.On this basis,a systematic investigation was conducted into the influence of parameters such as blast loading duration,lining thickness,and elastic modulus on the transient dynamic stress concentration factor(DSCF)of the tunnel,incorporating engineering data from theHongshan South Road tunnel group.The results indicate that the DSCF values in the secondary lining of the composite tunnel are greater than those in the surrounding rock.The elastic moduli of both the surrounding rock and the secondary lining have a significant influence on the DSCF of the lining.Therefore,under the premise of ensuring adequate stability of the surrounding rock,materials with lower stiffness should be preferentially selected for the secondary lining.Increasing the thickness of both the surrounding rock and the secondary lining can markedly reduce the DSCF within the lining.The analytical results can provide a theoretical basis for the anti-blast design of tunnels.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
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
Laser-driven inertial confinement fusion(ICF)is an important experimental platform for high-energy-density physics research under extreme conditions.In ICF research,high-quality shock waves are key to fusion energy re...Laser-driven inertial confinement fusion(ICF)is an important experimental platform for high-energy-density physics research under extreme conditions.In ICF research,high-quality shock waves are key to fusion energy release.The velocity interferometer system for any reflector(VISAR)is the most important diagnostic technique for measuring quantities such as shock wave and particle velocities with high precision and high spatiotemporal resolution.This paper provides a detailed introduction to the various configurations of VISAR on 10 and 100 kJ-level laser facilities in China,including Line VISAR,Dual-Axis VISAR,Wide-Angle VISAR,and Compressed Ultrafast Photography-VISAR.Recent advances and applications of VISAR diagnostics at these laser facilities are presented,and the future trend of development of high-spatiotemporal-resolution velocity diagnostic technology is described.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
Numerical simulations and theoretical models are developed in this paper for the Detonation-Wave/Boundary-Layer Interactions(DWBLIs)under reflections.Transient flow fields demonstrate the highly non-stationarity of th...Numerical simulations and theoretical models are developed in this paper for the Detonation-Wave/Boundary-Layer Interactions(DWBLIs)under reflections.Transient flow fields demonstrate the highly non-stationarity of the DWBLIs when Mach Reflection(MR)occur,and subsequent analyses show that the subsonic region introduced by the boundary layer exacerbates the instability.Further quantitative analyses show that viscosity has little effect on propulsive performance and the separation wave can be considered as an oblique detonation wave.Influence parameters to DWBLIs such as combustion chamber height,incoming Mach number,equivalence ratio,and inlet channel length are categorized and studied.Besides simulations,theoretical analytical modeling is established for Regular Reflection(RR)and MR of DWBLIs.Multiple formulas for the separation zone length are obtained according to the mass conservation under different transformation type between inviscid and viscid reflections.Comparison with the numerical simulations verifies the validity of the model and it can be further generalized to the curved DWBLIs.The developed model makes the theoretical solution process of DWBLIs possible and provides the key foundation for further analysis and solution.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
Using high-resolution observations,mesoscale simulations,and idealized experiments,this study investigates the mechanisms governing an episode of orographic convection initiation(CI)during the North China Heavy Rainfa...Using high-resolution observations,mesoscale simulations,and idealized experiments,this study investigates the mechanisms governing an episode of orographic convection initiation(CI)during the North China Heavy Rainfall Experiment.On 4 August 2024,repeated CI occurred over the eastern slopes of the Taihang Mountains in the late afternoon,subsequently enhancing an upstream downhill convective storm.Wind profiler radar data and dense automatic weather stations reveal that CI was supported by strengthening southeasterly upslope winds.These winds primarily resulted from the migration of the mountain-plain solenoid and the mountainward-propagating outflow from a convective cold pool over the plain,with sensitivity experiments showing the latter contributed roughly 22%of the wind strength.The upslope flows gradually transported unstable air from the plain to the slope,fostering CI.Mesoscale simulations further highlight the key role of orographic waves near the mountain ridge,which generated strong downslope winds.The near-surface convergence between downslope and upslope flows,combined with wave-induced divergence aloft,produced deep ascent over the slope.Removing mountain ridges weakened wave strength and reduced downslope wind speeds by~8 m s^(-1).Without orographic heating in the idealized simulation(i.e.,no mountain-plain solenoid),only strong wave descent occurred below 2km,inhibiting CI.These findings underscore the critical interplay among plain convection,orographic waves,and the mountain-plain solenoid,offering new insight into the processes controlling orographic CI in North China.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
The Hall effect of elastic waves has attracted much attention due to its unique properties.A hexagonal lattice phononic crystal plate model is designed in this paper.By changing the spatial symmetry of the unit cell,a...The Hall effect of elastic waves has attracted much attention due to its unique properties.A hexagonal lattice phononic crystal plate model is designed in this paper.By changing the spatial symmetry of the unit cell,a band gap for the A_(0) Lamb wave is opened.The existence of the edge state of the phononic crystal plate is obtained by finite element simulation.It is found that both zigzag-type edge and bridge edge are topological edge states by analysis of the band structure of the supercell.A rectangular model with a straight channel is designed and the simulation results show that the two types of channels are topologically protected only for the A_(0) mode Lamb wave but not for the S_(0) mode.In addition,the results of numerical simulation are verified by experimental data measured by a laser vibrometer.Finally,it is found that neither upside V-shaped channels nor channels with defects will affect the stable propagation of A_(0) Lamb waves along the proposed route.This proposed model and method are helpful in broadening the means of regulating elastic waves in phononic crystal structures,and extending practical application of topological edge states in such structures.展开更多
Adhesively bonded joints are widely used in modern lightweight structures due to their high strengthto-weight ratio and design flexibility.However,the reliable non-destructive evaluation of bond integrity remains a si...Adhesively bonded joints are widely used in modern lightweight structures due to their high strengthto-weight ratio and design flexibility.However,the reliable non-destructive evaluation of bond integrity remains a significant challenge.This study presents a numerical investigation of adhesively bonded joints with different adhesive properties using ultrasonic guided waves.The main focus of the investigation is to evaluate the feasibility of using guided waves to assess bond integrity,particularly for detecting challenging weak bonds.For this purpose,a theoretical analysis of dispersion curves was conducted,revealing that the S0 Lamb wave mode is significantly sensitive to variations in adhesive properties in the 300-700 kHz frequency range.Finite element modelling was used to analyse the propagation of guided waves in two scenarios:an adhesively bonded aluminum structure and a more complex configuration-adhesively bonded lap joints.The Short-Time Fourier Transform(STFT)was used to process the obtained results and determine the group velocities of guided waves.By analysing the group velocity characteristics,their dependence on the adhesive properties was identified.In the first scenario,a clear separation of S0 modes from A0 modes was observed in the STFT analysis,with a decrease in group velocity as adhesive stiffness increased.For the more complex lap joint scenario,the separation between A0 and S0 modes was less distinct.However,the analysis of the average group velocity shows a dependence of average group velocity on adhesive properties.This is similar to the first scenario.There is a decrease in average group velocity as adhesive stiffness increases.The results obtained demonstrate that guided wavebased methods have a high potential for non-destructive evaluation of adhesively bonded structures,including the detection of weak bonds.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
Waves are important physical phenomena in an ocean,and their accurate prediction is essential for ocean engineering,maritime traffic,and marine early warning systems.This study focuses on the Qinhuangdao Sea area loca...Waves are important physical phenomena in an ocean,and their accurate prediction is essential for ocean engineering,maritime traffic,and marine early warning systems.This study focuses on the Qinhuangdao Sea area located in the Bohai Sea,China.Herein,we use on-site wind data to correct the reanalysis wind data obtained from the European Centre for Medium-Range Weather Forecasts(ECMWF),improving the accuracy of boundary conditions.Then,we use the Simulating WAves Nearshore(SWAN)model to simulate the regional wave field over time.A regional wave-parameter prediction model is then developed using a limited number of sampled data(covering only 2 years,2020–2021);the model is based on the Whale Optimization Algorithm(WOA),convolutional neural networks(CNNs),and long short-term memory(LSTM)neural networks.WOA is used to optimize the CNN and LSTM framework;in this framework,CNN extracts spatial features,and the LSTM network captures temporal features,enabling accurate short and long-term predictions of wave height,period,and direction.The experimental results showed that despite the small sample size,the model achieves a goodness of fit of 0.9957 for wave height prediction,0.9973 for period,and 0.9749 for wave direction in short-term forecasting.As the prediction step size increases,the accuracy of the model decreases.When the prediction step size reaches 9 h,the root mean square error for the prediction of wave height,period,and direction increases to 0.2060 m,0.4582 s,and32.5358°,respectively.The reliability and applicability of the model are further validated by the experimental results.Our findings highlighted the potential of the developed model in operational wave forecasting,even with a limited number of sampled data.展开更多
文摘A new model of periodic structure is proposed and analyzed.This structure is composed of an inner fluid-conveying pipe with periodic material arrangement carrying periodic arrays of outer cantilever pipes.The generalized differential quadrature rule(GDQR)method combined with the Bloch theorem is used to calculate the vibration band gaps of the structure.Results are verified by the forced vibration responses obtained using the GDQR method.Results indicate that the first two band gaps of the fluid-conveying pipe with periodic material arrangement can get close to each other and move to low frequency regions by changing the length of cantilever pipes.For high fluid velocity values in which the first band gap starts from zero frequency,since the second band is very close to the first band,this periodic structure can be used for vibration reduction over a wide band gap starting from zero frequency.Based on these results,it can be concluded that instead of increasing the total size of the periodic structure,these periodic arrays of cantilever pipes can be implemented to create a wide ultra-low-frequency band gap.Finally,verification of the GDQR method shows that it can be used as a precise numerical method for vibration analysis of the structures such as fluid-conveying pipes and moving belts.
文摘This study aims to discuss the propagation characteristics of seismic Lamb wave and surface wave in a new radial gradient supercell seismic metamaterial(RGSSM).Different from the traditional seismic metamaterials with simple unit cells,the RGSSM consists of the supercells arranged periodically along the radial direction,and these supercells are composed of five kinds of unit cells with gradient filling rates.The dispersion curve and attenuation spectrum of the Lamb wave in RGSSM are studied with the finite element method combined with the supercell technology,generating a very low-frequency ultra-wide bandgap of 3.98-20 Hz,and a forbidden band generated by the localized modes forms multi-harmonic oscillators inside the supercell.Furthermore,it is found that the Young’s modulus of the soil is more sensitive to the effect of bandgap.In terms of surface wave,the RGSSM can produce rapid attenuation in the low frequency range of 5.2-8.5 Hz.Finally,a 3D model is designed to demonstrate the shielding performance of RGSSM against the seismic surface wave.The proposed RGSSM provides a new idea for the seismic isolation of ultra-wide and low-frequency seismic waves.
基金supported by the National Natural Science Foundation of China (Grant Nos. 42188101, 42174188, 42474217, 42330207, 42374193, 42241143, and 42025404)the National Key R&D Program of China (Grant Nos. 2022YFF0503700 and 2022YFF0503900)。
文摘Ultra-low-frequency(ULF) waves are ubiquitous in terrestrial and planetary environments, playing a crucial role in energy transfer and dissipation through wave–particle interactions within space plasmas. By performing a detailed event study in terms of particle distribution maps and wave–particle variable correlation maps, we report that ULF waves observed by the Mars Atmosphere and Volatile EvolutioN(MAVEN) spacecraft in the Martian foreshock can effectively modulate the suprathermal electron fluxes by the magnetic field fluctuations. In particular, the variations in electron fluxes at energies of ~10–100 eV are significant in the perpendicular direction, showing good relationships with changes in the wave field strength characterized by a correlation coefficient ~0.8. These findings demonstrate the generality of interactions of ULF waves with electrons, even at these low energies, highlighting the importance of such processes throughout the heliosphere.
文摘Nonlinear Rossby waves are used to describe typical wave phenomena in large-scale atmosphere andocean.Owing to the nonlinearity of the involved problems,the weakly nonlinear method,ie the derivative ex-pansion method,was mainly used to investigate Rossby waves under the combined effects of the generalizedβ-effect and the basic flow effect.The derivative expansion method has the advantage of capturing the multi-scalecharacteristics of wave processes simultaneously.In the case where the perturbation expansion is independentof secular terms,the nonlinear equations describing the amplitude evolution of nonlinear waves were derived,such as the Korteweg-de Vries equation,the Boussinesq equation and Zakharov-Kuznetsov equation.Both quali-tative and quantitative analyses indicate that the generalizedβ-effect is the key factor inducing the evolution ofRossby solitary waves.
基金supported by the National Key Research and Development Program(Grant No.2024YFF0508203)the National Natural Science Foundation of China(Grant No.52378475)the Science and Technology Innovation Special Project of Xiongan New Area,National Key R&D Program(Grant No.2025XAGG0056)。
文摘To address the complex seismic response of long tunnels longitudinally crossing heterogeneous geological formations,this study proposes a three-dimensional SV-wave oblique-incidence input method that accounts for the initial disturbance of the wave field induced by geological heterogeneity.The method transforms equivalent twodimensional free-field responses into equivalent nodal forces applied at the boundaries of a 3D numerical model.A longitudinally heterogeneous“hard-soft-hard”site and tunnel system is established,in which the surrounding rock is modeled using the Mohr-Coulomb constitutive law,while the concrete lining is described by the concrete damaged plasticity model.The deformation patterns and failure mechanisms of the site-tunnel system under SV-wave excitation are systematically investigated.The results indicate that seismic damage under SV-wave loading is mainly concentrated in the soft-rock region.Failure of the soft surrounding rock induces pronounced sliding of the overlying hard rock,and the tunnel suffers severe damage due to the combined effects of soft-rock failure and strong ground shaking.Parametric analyses further show that smaller impedance ratios,larger soft-rock widths,and larger incidence angles significantly intensify the seismic response of the tunnel.The findings of this study provide valuable insights for the seismic design of tunnels crossing longitudinally heterogeneous geological formations.
基金supported by the Research Project on Micro-Vibration Blasting Technology for Tunnels in High-Altitude Cold Regions(2024HX01)the Jiangxi“Ganpo Jun Cai”Program for Young Sci-Tech Talents(2024QT04)the Natural Science Foundation of Jiangxi Province(20242BAB204095).
文摘Based on the theory of wave dynamics,this study systematically derives the steady-state analytical solution for the scattering of plane SV-waves by composite lined tunnels in an infinite space using the wave function expansion method.On this basis,a theoretical calculation model for circular composite linings under blast loading is established.Based on the steady-state analytical solution,theδ(x)-function and the Heaviside step function are introduced to construct the Duhamel integral,transforming the transient wave problem into an integral form.By further incorporating the Fourier integral transform,an analytical solution for the transient response around a composite lining tunnel subjected to a plane blast SV wave is ultimately derived.The computational results of this study are subsequently validated against those reported in existing literature.On this basis,a systematic investigation was conducted into the influence of parameters such as blast loading duration,lining thickness,and elastic modulus on the transient dynamic stress concentration factor(DSCF)of the tunnel,incorporating engineering data from theHongshan South Road tunnel group.The results indicate that the DSCF values in the secondary lining of the composite tunnel are greater than those in the surrounding rock.The elastic moduli of both the surrounding rock and the secondary lining have a significant influence on the DSCF of the lining.Therefore,under the premise of ensuring adequate stability of the surrounding rock,materials with lower stiffness should be preferentially selected for the secondary lining.Increasing the thickness of both the surrounding rock and the secondary lining can markedly reduce the DSCF within the lining.The analytical results can provide a theoretical basis for the anti-blast design of tunnels.
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 National Key Laboratory of Plasma Physics,Laser Fusion Research Center,China Academy of Engineering Physics under the National Natural Science Foundation of China(Grant Nos.12127810 and 12475242).
文摘Laser-driven inertial confinement fusion(ICF)is an important experimental platform for high-energy-density physics research under extreme conditions.In ICF research,high-quality shock waves are key to fusion energy release.The velocity interferometer system for any reflector(VISAR)is the most important diagnostic technique for measuring quantities such as shock wave and particle velocities with high precision and high spatiotemporal resolution.This paper provides a detailed introduction to the various configurations of VISAR on 10 and 100 kJ-level laser facilities in China,including Line VISAR,Dual-Axis VISAR,Wide-Angle VISAR,and Compressed Ultrafast Photography-VISAR.Recent advances and applications of VISAR diagnostics at these laser facilities are presented,and the future trend of development of high-spatiotemporal-resolution velocity diagnostic technology is described.
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.
基金support of the National Natural Science Foundation of China(Nos.U20A2069,U21B6003,12302389 and 12472337)the Advanced Aero-Power Innovation Workstation,China(No.HKCX2024-01-017)。
文摘Numerical simulations and theoretical models are developed in this paper for the Detonation-Wave/Boundary-Layer Interactions(DWBLIs)under reflections.Transient flow fields demonstrate the highly non-stationarity of the DWBLIs when Mach Reflection(MR)occur,and subsequent analyses show that the subsonic region introduced by the boundary layer exacerbates the instability.Further quantitative analyses show that viscosity has little effect on propulsive performance and the separation wave can be considered as an oblique detonation wave.Influence parameters to DWBLIs such as combustion chamber height,incoming Mach number,equivalence ratio,and inlet channel length are categorized and studied.Besides simulations,theoretical analytical modeling is established for Regular Reflection(RR)and MR of DWBLIs.Multiple formulas for the separation zone length are obtained according to the mass conservation under different transformation type between inviscid and viscid reflections.Comparison with the numerical simulations verifies the validity of the model and it can be further generalized to the curved DWBLIs.The developed model makes the theoretical solution process of DWBLIs possible and provides the key foundation for further analysis and solution.
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 National Key Research and Development Program of China(Grant No.2024YFC3013003)the National Natural Science Foundation of China(Grant Nos.424B2033 and 42475002)+3 种基金projects supported by the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant Nos.SML2024SP035,SML2024SP012,311024001)the Guangdong Project of Basic and Applied Basic Research(Grant Nos.2024A1515510005 and2025A1515011974)the Key Innovation Team of the China Meteorological Administration(Grant No.CMA2023ZD08)the State Key Laboratory of Severe Weather Meteorological Science and Technology(Grant No.2025QZA10)。
文摘Using high-resolution observations,mesoscale simulations,and idealized experiments,this study investigates the mechanisms governing an episode of orographic convection initiation(CI)during the North China Heavy Rainfall Experiment.On 4 August 2024,repeated CI occurred over the eastern slopes of the Taihang Mountains in the late afternoon,subsequently enhancing an upstream downhill convective storm.Wind profiler radar data and dense automatic weather stations reveal that CI was supported by strengthening southeasterly upslope winds.These winds primarily resulted from the migration of the mountain-plain solenoid and the mountainward-propagating outflow from a convective cold pool over the plain,with sensitivity experiments showing the latter contributed roughly 22%of the wind strength.The upslope flows gradually transported unstable air from the plain to the slope,fostering CI.Mesoscale simulations further highlight the key role of orographic waves near the mountain ridge,which generated strong downslope winds.The near-surface convergence between downslope and upslope flows,combined with wave-induced divergence aloft,produced deep ascent over the slope.Removing mountain ridges weakened wave strength and reduced downslope wind speeds by~8 m s^(-1).Without orographic heating in the idealized simulation(i.e.,no mountain-plain solenoid),only strong wave descent occurred below 2km,inhibiting CI.These findings underscore the critical interplay among plain convection,orographic waves,and the mountain-plain solenoid,offering new insight into the processes controlling orographic CI in North China.
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.
文摘The Hall effect of elastic waves has attracted much attention due to its unique properties.A hexagonal lattice phononic crystal plate model is designed in this paper.By changing the spatial symmetry of the unit cell,a band gap for the A_(0) Lamb wave is opened.The existence of the edge state of the phononic crystal plate is obtained by finite element simulation.It is found that both zigzag-type edge and bridge edge are topological edge states by analysis of the band structure of the supercell.A rectangular model with a straight channel is designed and the simulation results show that the two types of channels are topologically protected only for the A_(0) mode Lamb wave but not for the S_(0) mode.In addition,the results of numerical simulation are verified by experimental data measured by a laser vibrometer.Finally,it is found that neither upside V-shaped channels nor channels with defects will affect the stable propagation of A_(0) Lamb waves along the proposed route.This proposed model and method are helpful in broadening the means of regulating elastic waves in phononic crystal structures,and extending practical application of topological edge states in such structures.
基金supported by the Research Council of Lithuania(LMTLT),agreement no.S-MIP-22-5.
文摘Adhesively bonded joints are widely used in modern lightweight structures due to their high strengthto-weight ratio and design flexibility.However,the reliable non-destructive evaluation of bond integrity remains a significant challenge.This study presents a numerical investigation of adhesively bonded joints with different adhesive properties using ultrasonic guided waves.The main focus of the investigation is to evaluate the feasibility of using guided waves to assess bond integrity,particularly for detecting challenging weak bonds.For this purpose,a theoretical analysis of dispersion curves was conducted,revealing that the S0 Lamb wave mode is significantly sensitive to variations in adhesive properties in the 300-700 kHz frequency range.Finite element modelling was used to analyse the propagation of guided waves in two scenarios:an adhesively bonded aluminum structure and a more complex configuration-adhesively bonded lap joints.The Short-Time Fourier Transform(STFT)was used to process the obtained results and determine the group velocities of guided waves.By analysing the group velocity characteristics,their dependence on the adhesive properties was identified.In the first scenario,a clear separation of S0 modes from A0 modes was observed in the STFT analysis,with a decrease in group velocity as adhesive stiffness increased.For the more complex lap joint scenario,the separation between A0 and S0 modes was less distinct.However,the analysis of the average group velocity shows a dependence of average group velocity on adhesive properties.This is similar to the first scenario.There is a decrease in average group velocity as adhesive stiffness increases.The results obtained demonstrate that guided wavebased methods have a high potential for non-destructive evaluation of adhesively bonded structures,including the detection of weak bonds.
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.
基金supported by the National Natural Science Foundation of China(Nos.52071057,52171247)the Liaoning Youth Elite Talent Program(No.XLYC220309)。
文摘Waves are important physical phenomena in an ocean,and their accurate prediction is essential for ocean engineering,maritime traffic,and marine early warning systems.This study focuses on the Qinhuangdao Sea area located in the Bohai Sea,China.Herein,we use on-site wind data to correct the reanalysis wind data obtained from the European Centre for Medium-Range Weather Forecasts(ECMWF),improving the accuracy of boundary conditions.Then,we use the Simulating WAves Nearshore(SWAN)model to simulate the regional wave field over time.A regional wave-parameter prediction model is then developed using a limited number of sampled data(covering only 2 years,2020–2021);the model is based on the Whale Optimization Algorithm(WOA),convolutional neural networks(CNNs),and long short-term memory(LSTM)neural networks.WOA is used to optimize the CNN and LSTM framework;in this framework,CNN extracts spatial features,and the LSTM network captures temporal features,enabling accurate short and long-term predictions of wave height,period,and direction.The experimental results showed that despite the small sample size,the model achieves a goodness of fit of 0.9957 for wave height prediction,0.9973 for period,and 0.9749 for wave direction in short-term forecasting.As the prediction step size increases,the accuracy of the model decreases.When the prediction step size reaches 9 h,the root mean square error for the prediction of wave height,period,and direction increases to 0.2060 m,0.4582 s,and32.5358°,respectively.The reliability and applicability of the model are further validated by the experimental results.Our findings highlighted the potential of the developed model in operational wave forecasting,even with a limited number of sampled data.
