A plasma screening model that accounts for electronic exchange-correlation effects and ionic nonideality in dense quantum plasmas is proposed.This model can be used as an input in various plasma interaction models to ...A plasma screening model that accounts for electronic exchange-correlation effects and ionic nonideality in dense quantum plasmas is proposed.This model can be used as an input in various plasma interaction models to calculate scattering cross-sections and transport properties.The applicability of the proposed plasma screening model is demonstrated using the example of the temperature relaxation rate in dense hydrogen and warm dense aluminum.Additionally,the conductivity of warm dense aluminum is computed in the regime where collisions are dominated by electron-ion scattering.The results obtained are compared with available theoretical results and simulation data.展开更多
Red clay,widely used as a subgrade material in southern China,requires a reliable evaluation of its dynamic behavior to ensure infrastructure safety.Long-term cyclic triaxial tests were conducted on red clay from typi...Red clay,widely used as a subgrade material in southern China,requires a reliable evaluation of its dynamic behavior to ensure infrastructure safety.Long-term cyclic triaxial tests were conducted on red clay from typical,complex subway subgrades to investigate its dynamic properties and shakedown behavior under intermittent cyclic loading.Results show that intermittent cyclic loading,especially with multiple amplitudes,causes greater axial plastic strain and lower post-cyclic strength than continuous loading.These effects diminish with increasing confining pressure.Notably,axial strain partially recovers during loading intervals,with recovery ratios depending on the number and sequence of pauses.Based on the rules of cumulative plastic strain rates and cumulative plastic strain increments,shakedown behavior for red clay under intermittent cyclic loading is divided into three categories:plastic shakedown,critical shakedown,and plastic creep.A quantitative shakedown limit criterion is proposed using the Boltzmann function.Shakedown behavior significantly influences the post-cyclic strengths,and the influence diminishes as confining pressure increases.Samples exhibiting plastic creep and plastic shakedown behavior have the lowest and highest strengths,and those with critical shakedown behaviors have medium strengths.Cyclic loading with relatively low-stress amplitude causes a hardening effect,while cyclic loading intermittence or cyclic loading with relatively high-stress amplitude causes a degradation effect,and both effects are mitigated by higher confining pressures.展开更多
Liquid-liquid phase separation(LLPS)of proteins and nucleic acids is a common phenomenon in cells that underlies the formation of membraneless organelles.Although the macroscopic behavior of biomolecular coacervates h...Liquid-liquid phase separation(LLPS)of proteins and nucleic acids is a common phenomenon in cells that underlies the formation of membraneless organelles.Although the macroscopic behavior of biomolecular coacervates has been elucidated by microscopy,the detailed dynamic properties of proteins/peptides during the LLPS process remain poorly characterized.Here,site-directed spin labeling-electron paramagnetic resonance(SDSL-EPR)spectroscopy was employed to characterize the dynamic properties of a minimal model LLPS system consisting of positively charged peptides and RNA.The degree of phase separation,indicated by broadening of the EPR spectrum of the spin-labeled peptide due to slow molecular tumbling,was monitored by EPR.In addition,three distinct populations with varying molecular motion during LLPS,featuring different spectral lineshapes,were identified.These populations included a fast motion component(Ⅰ),a slower motion component(Ⅱ)associated with peptides in the dispersed phase and an immobile component(Ⅲ)observed in the dense phase.With gradual titration of the peptides to RNA,the EPR spectrum gradually shifted,refiecting changes in the populations of the components.Together,SDSL-EPR method not only provides new insights into the dynamic behavior of biomolecules during LLPS,but also offers a sensitive method for biomolecular phase separation processes at the molecular level.展开更多
Controllable shock wave fracturing is an innovative engineering technique used for shale reservoir fracturing and reformation.Understanding the anisotropic fracture mechanism of shale under impact loading is vital for...Controllable shock wave fracturing is an innovative engineering technique used for shale reservoir fracturing and reformation.Understanding the anisotropic fracture mechanism of shale under impact loading is vital for optimizing shock wave fracturing equipment and enhancing shale oil production.In this study,using the well-known notched semi-circular bend(NSCB)sample and the novel double-edge notched flattened Brazilian disc(DNFBD)sample combined with a split Hopkinson pressure bar(SHPB),various dynamic anisotropic fracture properties of Lushan shale,including failure characteristics,fracture toughness,energy dissipation and crack propagation velocity,are comprehensively compared and discussed under mode Ⅰ and mode Ⅱ fracture scenarios.First,using a newly modified fracture criterion considering the strength anisotropy of shale,the DNFBD specimen is predicted to be a robust method for true mode Ⅱ fracture of anisotropic shale rocks.Our experimental results show that the dynamic mode Ⅱ fracture of shale induces a rougher and more complex fracture morphology and performs a higher fracture toughness or fracture energy compared to dynamic mode Ⅰ fracture.The minimal fracture toughness or fracture energy occurs in the Short-transverse orientation,while the maximal ones occur in the Divider orientation.In addition,it is interesting to find that the mode Ⅱ fracture toughness anisotropy index decreases more slowly than that in the mode Ⅰ fracture scenario.These results provide significant insights for understanding the different dynamic fracture mechanisms of anisotropic shale rocks under impact loading and have some beneficial implications for the controllable shock wave fracturing technique.展开更多
We theoretically studied the dynamic properties of the skyrmion driven by electromagnetic(EM)waves with spin angular momentum(SAM)and orbital angular momentum(OAM)using micromagnetic simulations.First,the guiding cent...We theoretically studied the dynamic properties of the skyrmion driven by electromagnetic(EM)waves with spin angular momentum(SAM)and orbital angular momentum(OAM)using micromagnetic simulations.First,the guiding centers of the skyrmion driven by EM waves with SAM,i.e.,left-handed and right-handed circularly polarized EM waves,present circular trajectories,while present elliptical trajectories under linear EM waves driving due to the superposition of oppositely polarized wave components.Second,the trajectories of the skyrmion driven by EM waves with OAM demonstrate similar behavior to that driven by linearly polarized EM waves.Because the wave vector intensity varies with the phase for both linearly polarized EM waves and EM waves with OAM,the angular momentum is transferred to the skyrmion non-uniformly,while the angular momentum is transferred to the skyrmion uniformly for left-handed and right-handed circularly polarized EM driving.Third,the dynamic properties of the skyrmion driven by EM waves with both SAM and OAM are investigated.It is found that the dynamic trajectories exhibit more complex behavior due to the contributions or competition of SAM and OAM.We investigate the characteristics of intrinsic gyration modes and frequency-dependent trajectories.Our research may provide insight into the dynamic properties of skyrmion manipulated by EM waves with SAM or OAM and provide a method for controlling skyrmion in spintronic devices.展开更多
By using the falling weight deflectometer（FWD）,the dynamic loading tests on different thickness of asphalt mixture pavement in different temperature were performed.The experimental results show that the effects of t...By using the falling weight deflectometer（FWD）,the dynamic loading tests on different thickness of asphalt mixture pavement in different temperature were performed.The experimental results show that the effects of temperature on dynamic properties of asphalt mixture are significant,and the thickness of asphalt mixture is also another important influence factor.The comparisons indicate that effect of temperature on the behaviors of dynamic loading properties and static loading properties of asphalt mixture were quite different.展开更多
In order to study the effects of loading condition and temperature on the dynamic properties of asphalt mixtures, the dynamic loading tests on different loading condition （various speeds and loads under a certain rou...In order to study the effects of loading condition and temperature on the dynamic properties of asphalt mixtures, the dynamic loading tests on different loading condition （various speeds and loads under a certain roughness） and temperature conditions were performed. The experimental result show that the dynamic properties of asphalt mixtures are influenced by vehicle load and speed, besides, the effects of temperature on dynamic properties of asphalt mixture are significant.展开更多
Fuzzy Petri net(FPN) has been extensively applied in industrial fields for knowledge-based systems or systems with uncertainty.Although the applications of FPN are known to be successful,the theoretical research of FP...Fuzzy Petri net(FPN) has been extensively applied in industrial fields for knowledge-based systems or systems with uncertainty.Although the applications of FPN are known to be successful,the theoretical research of FPN is still at an initial stage.To pave a way for further study,this work explores related dynamic properties of FPN including reachability,boundedness,safeness,liveness and fairness.The whole methodology is divided into two phases.In the first phase,a comparison between elementary net system(EN_system) and FPN is established to prove that the FPN is an extensive formalism of Petri nets using a backwards-compatible extension method.Next,current research results of dynamic properties are utilized to analyze FPN model.The results illustrate that FPN model is bounded,safe,weak live and fair,and can support theoretical evidences for designing related decomposition algorithm.展开更多
In this paper, a new theory for the dynamic properties of protein molecular system have been proposed by means of the analysis of the characteristics of the collective excitations generated under the localized fluctua...In this paper, a new theory for the dynamic properties of protein molecular system have been proposed by means of the analysis of the characteristics of the collective excitations generated under the localized fluctuation and the deformation of structure of the protein. Some new results obtained from this study show that the Davydov theory is an approximate and disadvantegeous theory.展开更多
Ab initio calculations,based on norm-conserving nonlocal pseudopotentials and density functional theory（DFT）,are performed to investigate the structural,elastic,dielectric,and vibrational properties of aluminum arse...Ab initio calculations,based on norm-conserving nonlocal pseudopotentials and density functional theory（DFT）,are performed to investigate the structural,elastic,dielectric,and vibrational properties of aluminum arsenide（AlAs） with a zinc-blende（B3） structure and a nickel arsenide（B81） structure under hydrostatic pressure.Firstly,the path for the phase transition from B3 to B81 is confirmed by analyzing the energies of different structures,which is in good agreement with previous theoretical results.Secondly,we find that the elastic constants,bulk modulus,static dielectric constants,and the optical phonon frequencies vary in a nearly linear manner under hydrostatic pressure.What is more,the softening mode of the transversal acoustic mode at the X point supports the phase transition in AlAs.展开更多
First principles calculations were used to explore the structural stability, mechanical properties, and thermodynamic properties of LaT2Al20(T = Ti, V, Cr, Nb, and Ta) intermetallics. The calculated formation enthalpy...First principles calculations were used to explore the structural stability, mechanical properties, and thermodynamic properties of LaT2Al20(T = Ti, V, Cr, Nb, and Ta) intermetallics. The calculated formation enthalpy and phonon frequencies indicate that LaT2Al20intermetallics exhibit the structural stability. The elastic moduli(B, G, E, and Hv) indicate that these intermetallics possess the better elastic properties than pure Al. The values of Poisson’s ratio v and B/G demonstrate that LaT2Al20intermetallics are all brittle materials. The anisotropy of elasticity and Young’s modulus(three-and two-dimensional figures) indicate that LaT2Al20compounds are anisotropic. Importantly, the calculated thermal quantities demonstrate that LaT2Al20intermetallics possess the better thermal physical properties than pure Al at high temperatures.展开更多
The structural, dielectric, lattice dynamical and thermodynamic properties of zinc-blende CdX （X=S, Se, Te） are studied by using a plane-wave pseudopotential method within the density-functional theory. Our calculat...The structural, dielectric, lattice dynamical and thermodynamic properties of zinc-blende CdX （X=S, Se, Te） are studied by using a plane-wave pseudopotential method within the density-functional theory. Our calculated lattice constants and bulk modulus are compared with the pubfished experimental and theoretical data. In addition, the Born effective charges, electronic dielectric tensors, phonon frequencies, and longitudinal opticaltransverse optical splitting are calculated by the linear-response approach. Some of the characteristics of the phonon-dispersion curves for zinc-blende CdX （X= S, Se, Te） are summarized. What is more, based on the lattice dynamical properties, we investigate the thermodynamic properties of CdX （X= S, Se, Te） and analyze the temperature dependences of the Helmholtz free energy F, the internal energy E, the entropy S and the constant-volume specific heat Cv. The results show that the heat capacities for CdTe, CdSe, and CdS approach approximately to the Petit-Dulong limit 6R.展开更多
The focus of this paper is on determination of the dynamic parameters of structural systems with viscoelastic (VE) dampers described by Maxwell rheological models. Such parameters could be obtained after solving the a...The focus of this paper is on determination of the dynamic parameters of structural systems with viscoelastic (VE) dampers described by Maxwell rheological models. Such parameters could be obtained after solving the appropriately defined nonlinear eigenvalue problem for frames with VE dampers. The solution to the nonlinear eigenvalue problem is obtained by equating to zero the determinant of the considered system of equations. Apart from complex conjugate eigenvalues, the real ones occurred when dampers that are described by the classic Maxwell model, are also determined.展开更多
Based on the density functional theory within the local density approximation (LDA), we studied the electronic, elastic, and dynamic properties of AgNbO<sub>3</sub> and AgTaO<sub>3</sub> compou...Based on the density functional theory within the local density approximation (LDA), we studied the electronic, elastic, and dynamic properties of AgNbO<sub>3</sub> and AgTaO<sub>3</sub> compounds under pressure. The elastic constants, optic and static dielectric constants, born effective charges, and dynamic properties of AgNbO<sub>3</sub> and AgTaO<sub>3</sub> in cubic phase were studied as pressure dependences with the ab initio method. For these compounds, we have also calculated the bulk modulus, Young’s modulus, shear modulus, Vickers hardness, Poisson’s ratio, anisotropy factor, sound velocities, and Debye temperature from the obtained elastic constants. In addition, the brittleness and ductility properties of these compounds were estimated from Poisson’s ratio and Pugh’s rule (G/B). Our calculated values also show that AgNbO<sub>3</sub> (0.37) and AgTaO<sub>3</sub> (0.39) behave as ductile materials and steer away from brittleness by increasing pressure. The calculated values of Vicker hardness for both compounds indicate that they are soft materials. The results show that band gaps, elastic constants, elastic modules, and dynamic properties for both compounds are sensitive to pressure changes. We have also made some comparisons with related experimental and theoretical data that is available in the literature.展开更多
The variation of casting hot spot with proceeding of solidification andcomponents of casting-mold system is studied by the technique of numerical simulation ofsolidification. The result shows that the thickest part of...The variation of casting hot spot with proceeding of solidification andcomponents of casting-mold system is studied by the technique of numerical simulation ofsolidification. The result shows that the thickest part of casting is not exactly the last part ofsolidification in the casting, while the last part of solidification is not exactly casting hot spotat the early stage of solidification. The location, size, shape and number of casting hot spotchange with geomitric, physical and technological factors of the casting-mold system such asthickness of the casting secondary wall and with the passage of time in the course of thesolidification. The former is known as the systematic property of hot spot and the latter, dynamicproperty. Only when the properties of hot spot are grasped completely and accurately, can it be fedmore effectively. By doing so, not only sound castings can be obtained, but also riser efficiencycan be improved.展开更多
Estimation of strain-dependent dynamic soil properties, e.g. the shear modulus and damping ratio, along with the liquefaction potential parameters, is extremely important for the assessment and analysis of almost all ...Estimation of strain-dependent dynamic soil properties, e.g. the shear modulus and damping ratio, along with the liquefaction potential parameters, is extremely important for the assessment and analysis of almost all geotechnical problems involving dynamic loading. This paper presents the dynamic properties and liquefaction behaviour of cohesive soil subjected to staged cyclic loading, which may be caused by main shocks of earthquakes preceded or followed by minor foreshocks or aftershocks, respectively. Cyclic triaxial tests were conducted on the specimens prepared at different dry densities （1.5 g/cm3 and 1.75 g/cm3） and different water contents ranging from 8% to 25%. The results indicated that the shear modulus reduction （G/Gmax） and damping ratio of the specimen remain unaffected due to the changes in the initial dry density and water content. Damping ratio is significantly affected by confining pressure, whereas G/Gmax is affected marginally. It was seen that the liquefaction criterion of cohesive soils based on single-amplitude shear strain （3.75% or the strain at which excess pore water pressure ratio becomes equal to 1, whichever is lower） depends on the initial state of soils and applied stresses. The dynamic model of the regional soil, obtained as an outcome of the cyclic triaxial tests, can be successfully used for ground response analysis of the region.展开更多
A numerical solution based on the Steffensen stable point iterative method is proposed to resolve the transcendental frequency equation of a stay cable-damper system. The frequency equation, which considers clamped su...A numerical solution based on the Steffensen stable point iterative method is proposed to resolve the transcendental frequency equation of a stay cable-damper system. The frequency equation, which considers clamped supports and fl exural rigidity of the cable, is intended to investigate the infl uence of the parameters of the cable damper system on its dynamic characteristics. Two factors involved in the design and construction phases, the damping coeffi cient induced by external dampers and the cable tension, are the focus of this study. Their impact on modal frequencies and damping ratios in these two phases of cable-damper systems are investigated by resolving the equation with the proposed solution. It is shown that the damping coeffi cient and cable tension exert more noticeable effects on the modal damping ratios than on the modal frequencies of stay cable-damper systems, and the two factors can serve as design variables in the design phase and as adjustment factors in the construction phase. On the basis of the results, a roadmap for system-level optimal design of stay cable-damper systems that can achieve global optimal vibration suppression for the entire bridge is proposed and discussed.展开更多
The lattice dynamic, elastic, and thermodynamic properties of Be Se were investigated with first principles calculations. The phase transition pressure from the zinc blende（B3） to the nickel arsenide（B8） structure...The lattice dynamic, elastic, and thermodynamic properties of Be Se were investigated with first principles calculations. The phase transition pressure from the zinc blende（B3） to the nickel arsenide（B8） structure of Be Se was determined. The elastic stability analysis suggests that the B3 structure Be Se is mechanically stable in the applied pressure range of 0-50 GPa. Our lattice dynamic calculations show that the B3 structure is lattice dynamically stable under high pressure. Within the quasiharmonic approximation, the thermodynamic properties including the constant volume heat capacity and constant pressure heat capacity are predicted.展开更多
Experimental studies were conducted on two high-strength steel plate-frame structures with different truss spacings under various impact velocities to investigate the dynamic mechanical properties of hull plate-frame ...Experimental studies were conducted on two high-strength steel plate-frame structures with different truss spacings under various impact velocities to investigate the dynamic mechanical properties of hull plate-frame structures under drop weight impact.The results showed that decreasing the main beam spacing can effectively increase the structural stiffness,reduce the maximum deformation,and increase the damage range.Furthermore,to simulate the impact tests accurately,static and dynamic tensile tests at different strain rates were carried out,and the Cowper-Symonds model parameters were fitted via experimental data.The material properties obtained from the tensile tests were used as inputs for numerical simulations with the numerical results coincide with the experimental results.A systematic analysis and discussion were conducted on the effects of truss spacing and truss width on the dynamic response of the reinforced plates,and an optimal range for the ratio of truss spacing to truss width was proposed.In addition,a mesh size sensitivity analysis for ship hull plate frame collision simulations was performed.The applicability of the EPS,MMC,and RTCL failure criteria in the simulation of plate-frame structures was investigated via finite element simulations of falling weight impact tests.The research findings provide a reference for ship hull structure design and resilience assessment.展开更多
The mechanical properties of secondary cells are crucial to the safety and reliability of battery packs,which can fail due to extrusion and vibration in a vehicle crash.To analyze the structural response of the second...The mechanical properties of secondary cells are crucial to the safety and reliability of battery packs,which can fail due to extrusion and vibration in a vehicle crash.To analyze the structural response of the secondary cell and its other dynamic behaviors,the experiment and some numerical simulations were carried out based on single reference impact testing.Then,an equivalent constitutive relationship of the secondary cell was proposed to reveal the dynamic properties and used to guide the safety estimation of the battery pack.As the input parameter to the finite element model,the equivalent constitutive relationship,including but not limited to the elastic modulus and stain-stress curve,determines the simulation precision of the battery packs.Compared to the experimental results of the natural frequency of the battery pack,the simulation error is below 2%when the elastic modulus of the secondary cell in the battery pack has been verified.展开更多
基金funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan Grant No.AP19678033“The study of the transport and optical properties of hydrogen at high pressure.”。
文摘A plasma screening model that accounts for electronic exchange-correlation effects and ionic nonideality in dense quantum plasmas is proposed.This model can be used as an input in various plasma interaction models to calculate scattering cross-sections and transport properties.The applicability of the proposed plasma screening model is demonstrated using the example of the temperature relaxation rate in dense hydrogen and warm dense aluminum.Additionally,the conductivity of warm dense aluminum is computed in the regime where collisions are dominated by electron-ion scattering.The results obtained are compared with available theoretical results and simulation data.
基金the support of the National Natural Science Foundation of China(Grant No.52108319)the Natural Science Foundation of Jiangxi Province(20224BAB214069)。
文摘Red clay,widely used as a subgrade material in southern China,requires a reliable evaluation of its dynamic behavior to ensure infrastructure safety.Long-term cyclic triaxial tests were conducted on red clay from typical,complex subway subgrades to investigate its dynamic properties and shakedown behavior under intermittent cyclic loading.Results show that intermittent cyclic loading,especially with multiple amplitudes,causes greater axial plastic strain and lower post-cyclic strength than continuous loading.These effects diminish with increasing confining pressure.Notably,axial strain partially recovers during loading intervals,with recovery ratios depending on the number and sequence of pauses.Based on the rules of cumulative plastic strain rates and cumulative plastic strain increments,shakedown behavior for red clay under intermittent cyclic loading is divided into three categories:plastic shakedown,critical shakedown,and plastic creep.A quantitative shakedown limit criterion is proposed using the Boltzmann function.Shakedown behavior significantly influences the post-cyclic strengths,and the influence diminishes as confining pressure increases.Samples exhibiting plastic creep and plastic shakedown behavior have the lowest and highest strengths,and those with critical shakedown behaviors have medium strengths.Cyclic loading with relatively low-stress amplitude causes a hardening effect,while cyclic loading intermittence or cyclic loading with relatively high-stress amplitude causes a degradation effect,and both effects are mitigated by higher confining pressures.
基金supported by the National Natural Science Foundation of China(No.21927814)the National Key Research and Development Program of China(Nos.2019YFA0405600,2019YFA0706900,2021YFA1200104,2022YFC3400500)+2 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDB0540200,XDB37040201)Plans for Major Provincial Science&Technology Projects(No.202303a07020004)the Youth Innovation Promotion Association,CAS(No.2022455)。
文摘Liquid-liquid phase separation(LLPS)of proteins and nucleic acids is a common phenomenon in cells that underlies the formation of membraneless organelles.Although the macroscopic behavior of biomolecular coacervates has been elucidated by microscopy,the detailed dynamic properties of proteins/peptides during the LLPS process remain poorly characterized.Here,site-directed spin labeling-electron paramagnetic resonance(SDSL-EPR)spectroscopy was employed to characterize the dynamic properties of a minimal model LLPS system consisting of positively charged peptides and RNA.The degree of phase separation,indicated by broadening of the EPR spectrum of the spin-labeled peptide due to slow molecular tumbling,was monitored by EPR.In addition,three distinct populations with varying molecular motion during LLPS,featuring different spectral lineshapes,were identified.These populations included a fast motion component(Ⅰ),a slower motion component(Ⅱ)associated with peptides in the dispersed phase and an immobile component(Ⅲ)observed in the dense phase.With gradual titration of the peptides to RNA,the EPR spectrum gradually shifted,refiecting changes in the populations of the components.Together,SDSL-EPR method not only provides new insights into the dynamic behavior of biomolecules during LLPS,but also offers a sensitive method for biomolecular phase separation processes at the molecular level.
基金supported by the National Natural Science Foundation of China(Grant No.12302500)the National Key Research and Development Program of China(Grant No.2020YFA0710503)Postdoctoral Fellowship Program(Grade B)of China Postdoctoral Science Foundation(Grant No.GBZ20230022).
文摘Controllable shock wave fracturing is an innovative engineering technique used for shale reservoir fracturing and reformation.Understanding the anisotropic fracture mechanism of shale under impact loading is vital for optimizing shock wave fracturing equipment and enhancing shale oil production.In this study,using the well-known notched semi-circular bend(NSCB)sample and the novel double-edge notched flattened Brazilian disc(DNFBD)sample combined with a split Hopkinson pressure bar(SHPB),various dynamic anisotropic fracture properties of Lushan shale,including failure characteristics,fracture toughness,energy dissipation and crack propagation velocity,are comprehensively compared and discussed under mode Ⅰ and mode Ⅱ fracture scenarios.First,using a newly modified fracture criterion considering the strength anisotropy of shale,the DNFBD specimen is predicted to be a robust method for true mode Ⅱ fracture of anisotropic shale rocks.Our experimental results show that the dynamic mode Ⅱ fracture of shale induces a rougher and more complex fracture morphology and performs a higher fracture toughness or fracture energy compared to dynamic mode Ⅰ fracture.The minimal fracture toughness or fracture energy occurs in the Short-transverse orientation,while the maximal ones occur in the Divider orientation.In addition,it is interesting to find that the mode Ⅱ fracture toughness anisotropy index decreases more slowly than that in the mode Ⅰ fracture scenario.These results provide significant insights for understanding the different dynamic fracture mechanisms of anisotropic shale rocks under impact loading and have some beneficial implications for the controllable shock wave fracturing technique.
文摘We theoretically studied the dynamic properties of the skyrmion driven by electromagnetic(EM)waves with spin angular momentum(SAM)and orbital angular momentum(OAM)using micromagnetic simulations.First,the guiding centers of the skyrmion driven by EM waves with SAM,i.e.,left-handed and right-handed circularly polarized EM waves,present circular trajectories,while present elliptical trajectories under linear EM waves driving due to the superposition of oppositely polarized wave components.Second,the trajectories of the skyrmion driven by EM waves with OAM demonstrate similar behavior to that driven by linearly polarized EM waves.Because the wave vector intensity varies with the phase for both linearly polarized EM waves and EM waves with OAM,the angular momentum is transferred to the skyrmion non-uniformly,while the angular momentum is transferred to the skyrmion uniformly for left-handed and right-handed circularly polarized EM driving.Third,the dynamic properties of the skyrmion driven by EM waves with both SAM and OAM are investigated.It is found that the dynamic trajectories exhibit more complex behavior due to the contributions or competition of SAM and OAM.We investigate the characteristics of intrinsic gyration modes and frequency-dependent trajectories.Our research may provide insight into the dynamic properties of skyrmion manipulated by EM waves with SAM or OAM and provide a method for controlling skyrmion in spintronic devices.
基金Funded by the Science and Technology Program of Communications Department of Henan Province (No.200612)
文摘By using the falling weight deflectometer（FWD）,the dynamic loading tests on different thickness of asphalt mixture pavement in different temperature were performed.The experimental results show that the effects of temperature on dynamic properties of asphalt mixture are significant,and the thickness of asphalt mixture is also another important influence factor.The comparisons indicate that effect of temperature on the behaviors of dynamic loading properties and static loading properties of asphalt mixture were quite different.
基金Funded by the Science and Technology Program of Communications Depart-ment of Henan Province(No.2006P335)
文摘In order to study the effects of loading condition and temperature on the dynamic properties of asphalt mixtures, the dynamic loading tests on different loading condition （various speeds and loads under a certain roughness） and temperature conditions were performed. The experimental result show that the dynamic properties of asphalt mixtures are influenced by vehicle load and speed, besides, the effects of temperature on dynamic properties of asphalt mixture are significant.
基金Project(R.J13000.7828.4F721)supported by Soft Computing Research Group(SCRP),Research Management Centre(RMC),UTM and Ministry of Higher Education Malaysia(MOHE)for Financial Support Through the Fundamental Research Grant Scheme(FRGS),MalaysiaProject(61462029)supported by the National Natural Science Foundation of China
文摘Fuzzy Petri net(FPN) has been extensively applied in industrial fields for knowledge-based systems or systems with uncertainty.Although the applications of FPN are known to be successful,the theoretical research of FPN is still at an initial stage.To pave a way for further study,this work explores related dynamic properties of FPN including reachability,boundedness,safeness,liveness and fairness.The whole methodology is divided into two phases.In the first phase,a comparison between elementary net system(EN_system) and FPN is established to prove that the FPN is an extensive formalism of Petri nets using a backwards-compatible extension method.Next,current research results of dynamic properties are utilized to analyze FPN model.The results illustrate that FPN model is bounded,safe,weak live and fair,and can support theoretical evidences for designing related decomposition algorithm.
文摘In this paper, a new theory for the dynamic properties of protein molecular system have been proposed by means of the analysis of the characteristics of the collective excitations generated under the localized fluctuation and the deformation of structure of the protein. Some new results obtained from this study show that the Davydov theory is an approximate and disadvantegeous theory.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11047031)the Natural Science Foundation of Guangxi Zhuang Autonomous Region,China (Grant No. 2011GXNSFC018003)the Open Foundation of the Key Laboratory of New Processing Technology for Nonferrous Metals and Materials,China (Grant No. GXKFJ09-16)
文摘Ab initio calculations,based on norm-conserving nonlocal pseudopotentials and density functional theory（DFT）,are performed to investigate the structural,elastic,dielectric,and vibrational properties of aluminum arsenide（AlAs） with a zinc-blende（B3） structure and a nickel arsenide（B81） structure under hydrostatic pressure.Firstly,the path for the phase transition from B3 to B81 is confirmed by analyzing the energies of different structures,which is in good agreement with previous theoretical results.Secondly,we find that the elastic constants,bulk modulus,static dielectric constants,and the optical phonon frequencies vary in a nearly linear manner under hydrostatic pressure.What is more,the softening mode of the transversal acoustic mode at the X point supports the phase transition in AlAs.
基金Project supported by the Program for Ph.D Start-up Fund of Liaoning Province of China(Grant No.201601161)
文摘First principles calculations were used to explore the structural stability, mechanical properties, and thermodynamic properties of LaT2Al20(T = Ti, V, Cr, Nb, and Ta) intermetallics. The calculated formation enthalpy and phonon frequencies indicate that LaT2Al20intermetallics exhibit the structural stability. The elastic moduli(B, G, E, and Hv) indicate that these intermetallics possess the better elastic properties than pure Al. The values of Poisson’s ratio v and B/G demonstrate that LaT2Al20intermetallics are all brittle materials. The anisotropy of elasticity and Young’s modulus(three-and two-dimensional figures) indicate that LaT2Al20compounds are anisotropic. Importantly, the calculated thermal quantities demonstrate that LaT2Al20intermetallics possess the better thermal physical properties than pure Al at high temperatures.
基金Supported by the National Natural Science Foundation of China under Grant No 11374217
文摘The structural, dielectric, lattice dynamical and thermodynamic properties of zinc-blende CdX （X=S, Se, Te） are studied by using a plane-wave pseudopotential method within the density-functional theory. Our calculated lattice constants and bulk modulus are compared with the pubfished experimental and theoretical data. In addition, the Born effective charges, electronic dielectric tensors, phonon frequencies, and longitudinal opticaltransverse optical splitting are calculated by the linear-response approach. Some of the characteristics of the phonon-dispersion curves for zinc-blende CdX （X= S, Se, Te） are summarized. What is more, based on the lattice dynamical properties, we investigate the thermodynamic properties of CdX （X= S, Se, Te） and analyze the temperature dependences of the Helmholtz free energy F, the internal energy E, the entropy S and the constant-volume specific heat Cv. The results show that the heat capacities for CdTe, CdSe, and CdS approach approximately to the Petit-Dulong limit 6R.
基金the financial support received from the Poznan University of Technology(Grant No.DS 11-088/12)in connection with this work.
文摘The focus of this paper is on determination of the dynamic parameters of structural systems with viscoelastic (VE) dampers described by Maxwell rheological models. Such parameters could be obtained after solving the appropriately defined nonlinear eigenvalue problem for frames with VE dampers. The solution to the nonlinear eigenvalue problem is obtained by equating to zero the determinant of the considered system of equations. Apart from complex conjugate eigenvalues, the real ones occurred when dampers that are described by the classic Maxwell model, are also determined.
文摘Based on the density functional theory within the local density approximation (LDA), we studied the electronic, elastic, and dynamic properties of AgNbO<sub>3</sub> and AgTaO<sub>3</sub> compounds under pressure. The elastic constants, optic and static dielectric constants, born effective charges, and dynamic properties of AgNbO<sub>3</sub> and AgTaO<sub>3</sub> in cubic phase were studied as pressure dependences with the ab initio method. For these compounds, we have also calculated the bulk modulus, Young’s modulus, shear modulus, Vickers hardness, Poisson’s ratio, anisotropy factor, sound velocities, and Debye temperature from the obtained elastic constants. In addition, the brittleness and ductility properties of these compounds were estimated from Poisson’s ratio and Pugh’s rule (G/B). Our calculated values also show that AgNbO<sub>3</sub> (0.37) and AgTaO<sub>3</sub> (0.39) behave as ductile materials and steer away from brittleness by increasing pressure. The calculated values of Vicker hardness for both compounds indicate that they are soft materials. The results show that band gaps, elastic constants, elastic modules, and dynamic properties for both compounds are sensitive to pressure changes. We have also made some comparisons with related experimental and theoretical data that is available in the literature.
基金This project is supported by Science Technology Development Foundation of Shanghai(No.0lJCl400l)+1 种基金Scientific Foundation of Hebei University of ScienceTechnology (No.XZ9906)
文摘The variation of casting hot spot with proceeding of solidification andcomponents of casting-mold system is studied by the technique of numerical simulation ofsolidification. The result shows that the thickest part of casting is not exactly the last part ofsolidification in the casting, while the last part of solidification is not exactly casting hot spotat the early stage of solidification. The location, size, shape and number of casting hot spotchange with geomitric, physical and technological factors of the casting-mold system such asthickness of the casting secondary wall and with the passage of time in the course of thesolidification. The former is known as the systematic property of hot spot and the latter, dynamicproperty. Only when the properties of hot spot are grasped completely and accurately, can it be fedmore effectively. By doing so, not only sound castings can be obtained, but also riser efficiencycan be improved.
文摘Estimation of strain-dependent dynamic soil properties, e.g. the shear modulus and damping ratio, along with the liquefaction potential parameters, is extremely important for the assessment and analysis of almost all geotechnical problems involving dynamic loading. This paper presents the dynamic properties and liquefaction behaviour of cohesive soil subjected to staged cyclic loading, which may be caused by main shocks of earthquakes preceded or followed by minor foreshocks or aftershocks, respectively. Cyclic triaxial tests were conducted on the specimens prepared at different dry densities （1.5 g/cm3 and 1.75 g/cm3） and different water contents ranging from 8% to 25%. The results indicated that the shear modulus reduction （G/Gmax） and damping ratio of the specimen remain unaffected due to the changes in the initial dry density and water content. Damping ratio is significantly affected by confining pressure, whereas G/Gmax is affected marginally. It was seen that the liquefaction criterion of cohesive soils based on single-amplitude shear strain （3.75% or the strain at which excess pore water pressure ratio becomes equal to 1, whichever is lower） depends on the initial state of soils and applied stresses. The dynamic model of the regional soil, obtained as an outcome of the cyclic triaxial tests, can be successfully used for ground response analysis of the region.
基金Key State Laboratories Freedom Research Project under Grant No.SLDRCE09-D-01the Fundamental Research Funds for the Central Universities,the Project of National Key Technology R&D Program in the 12th Five Year Plan of China under Grant No.2012BAJ11B01+2 种基金National Natural Science Foundation of China under Grant No.50978196State Meteorological Administration Special Funds of Meteorological Industry Research under Grant No.201306102the Ministry of Education of China under Grant No.2008B090500222
文摘A numerical solution based on the Steffensen stable point iterative method is proposed to resolve the transcendental frequency equation of a stay cable-damper system. The frequency equation, which considers clamped supports and fl exural rigidity of the cable, is intended to investigate the infl uence of the parameters of the cable damper system on its dynamic characteristics. Two factors involved in the design and construction phases, the damping coeffi cient induced by external dampers and the cable tension, are the focus of this study. Their impact on modal frequencies and damping ratios in these two phases of cable-damper systems are investigated by resolving the equation with the proposed solution. It is shown that the damping coeffi cient and cable tension exert more noticeable effects on the modal damping ratios than on the modal frequencies of stay cable-damper systems, and the two factors can serve as design variables in the design phase and as adjustment factors in the construction phase. On the basis of the results, a roadmap for system-level optimal design of stay cable-damper systems that can achieve global optimal vibration suppression for the entire bridge is proposed and discussed.
基金Funded by the National Natural Science Foundation of China(Nos.11447176 and 11447152)the The National Scholastic Athletics Foundation(No.U1230201)the Doctor Foundation of Southwest University of Science and Technology(Nos.13zx7137 and 14zx7167)
文摘The lattice dynamic, elastic, and thermodynamic properties of Be Se were investigated with first principles calculations. The phase transition pressure from the zinc blende（B3） to the nickel arsenide（B8） structure of Be Se was determined. The elastic stability analysis suggests that the B3 structure Be Se is mechanically stable in the applied pressure range of 0-50 GPa. Our lattice dynamic calculations show that the B3 structure is lattice dynamically stable under high pressure. Within the quasiharmonic approximation, the thermodynamic properties including the constant volume heat capacity and constant pressure heat capacity are predicted.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52171311 and 5227127).
文摘Experimental studies were conducted on two high-strength steel plate-frame structures with different truss spacings under various impact velocities to investigate the dynamic mechanical properties of hull plate-frame structures under drop weight impact.The results showed that decreasing the main beam spacing can effectively increase the structural stiffness,reduce the maximum deformation,and increase the damage range.Furthermore,to simulate the impact tests accurately,static and dynamic tensile tests at different strain rates were carried out,and the Cowper-Symonds model parameters were fitted via experimental data.The material properties obtained from the tensile tests were used as inputs for numerical simulations with the numerical results coincide with the experimental results.A systematic analysis and discussion were conducted on the effects of truss spacing and truss width on the dynamic response of the reinforced plates,and an optimal range for the ratio of truss spacing to truss width was proposed.In addition,a mesh size sensitivity analysis for ship hull plate frame collision simulations was performed.The applicability of the EPS,MMC,and RTCL failure criteria in the simulation of plate-frame structures was investigated via finite element simulations of falling weight impact tests.The research findings provide a reference for ship hull structure design and resilience assessment.
基金supported by the 2019 Postdoctoral Research Project funded by Hefei Municipal Bureau of Human Resources and Social Security and the National key R&D Program of China(2017YFB0102101).
文摘The mechanical properties of secondary cells are crucial to the safety and reliability of battery packs,which can fail due to extrusion and vibration in a vehicle crash.To analyze the structural response of the secondary cell and its other dynamic behaviors,the experiment and some numerical simulations were carried out based on single reference impact testing.Then,an equivalent constitutive relationship of the secondary cell was proposed to reveal the dynamic properties and used to guide the safety estimation of the battery pack.As the input parameter to the finite element model,the equivalent constitutive relationship,including but not limited to the elastic modulus and stain-stress curve,determines the simulation precision of the battery packs.Compared to the experimental results of the natural frequency of the battery pack,the simulation error is below 2%when the elastic modulus of the secondary cell in the battery pack has been verified.
