We consider matter-wave solitons in spin-orbit coupled Bose-Einstein condensates embedded in an optical lattice and study the dynamics of the soliton within the framework of Gross-Pitaevskii equations.We express spin ...We consider matter-wave solitons in spin-orbit coupled Bose-Einstein condensates embedded in an optical lattice and study the dynamics of the soliton within the framework of Gross-Pitaevskii equations.We express spin components of the soliton pair in terms of nonlinear Bloch equations and investigate the effective spin dynamics.It is seen that the effective magnetic field that appears in the Bloch equation is affected by optical lattices,and thus the optical lattice influences the precessional frequency of the spin components.We make use of numerical approaches to investigate the dynamical behavior of density profiles and center-of-mass of the soliton pair in the presence of the optical lattice.It is shown that the spin density is periodically varying due to flipping of spinors between the two states.The amplitude of spin-flipping oscillation increases with lattice strength.We find that the system can also exhibit interesting nonlinear behavior for chosen values of parameters.We present a fixed point analysis to study the effects of optical lattices on the nonlinear dynamics of the spin components.It is seen that the optical lattice can act as a control parameter to change the dynamical behavior of the spin components from periodic to chaotic.展开更多
Railway bridges are continuously loaded by railway trains;therefore, it is important to understand the nonlinear seismic response of the Vehicle-Bridge Interaction (VBI) system under strong earthquakes. For this purpo...Railway bridges are continuously loaded by railway trains;therefore, it is important to understand the nonlinear seismic response of the Vehicle-Bridge Interaction (VBI) system under strong earthquakes. For this purpose, the nonlinear behavior of the pier was introduced into the in-house VBI solvers. The nonlinear the seismic response of the VBI system was comprehensively evaluated using this model, and the effect of the vehicle dynamics on seismic performance of the bridge was identified. It was found that the seismic responses of most simply-supported bridges were reduced in the presence of railway trains due to the out-of-phase motion of the vehicle-bridge system. Meanwhile, the nonlinear behavior of the pier can reduce the vehicle’s seismic responses. Therefore, ignoring the nonlinear behavior of the pier during strong earthquakes can significantly overestimate the seismic response of the vehicle.展开更多
A conceptual model for microscopic-macroscopic slow-fast stochastic systems is considered. A dynamical reduction procedure is presented in order to extract effective dynamics for this kind of systems. Under appropriat...A conceptual model for microscopic-macroscopic slow-fast stochastic systems is considered. A dynamical reduction procedure is presented in order to extract effective dynamics for this kind of systems. Under appropriate assumptions, the effective system is shown to approximate the original system, in the sense of a probabilistic convergence.展开更多
The dynamics of blood lead (Pb-B) and blood zinc protoporphyrin (ZPP-B) of women in early pregnancy and parturient women with lead exposure and the effects on fetus development were investigated. Pb-B of lead-exposed ...The dynamics of blood lead (Pb-B) and blood zinc protoporphyrin (ZPP-B) of women in early pregnancy and parturient women with lead exposure and the effects on fetus development were investigated. Pb-B of lead-exposed women was high: 0.984 μmol/L (20.38 μg/dl) and ZPP was 84.52μg/dl. Cord blood Pb-B was 0.896 μmol/L(18.56μg/dl)and cord blood ZPP was 69.24μg/dl. In the control group, Pb-B was 0.261μmol/L(5.41μg/dl), ZPP-B, 37.59 μg/dl, cord blood, Pb-B 0.34 μmol/L (7.93 μg/dl), and cord ZPP-B 49.0μg/dl. There was a significant correlation between blood lead and blood ZPP, maternal Pb-B and cord Pb-B, maternal Pb-B and cord ZPP-B. The significance of the consistency of high level Pb-B and the effects on fetus development is discussed.展开更多
The dynamic effect is a very important issue widely debated by scholars when studying the genetic and disaster-causing mechanisms of earthquake-triggered landslides.First,the dynamic effect mechanism and phenomena of ...The dynamic effect is a very important issue widely debated by scholars when studying the genetic and disaster-causing mechanisms of earthquake-triggered landslides.First,the dynamic effect mechanism and phenomena of earthquake-triggered landslides were summarized in this paper.Then,the primary types of dynamic effects were further used to interpret the Mogangling landslide in Moxi Town of Luding County,China.A field investigation,remote sensing,numerical calculation and theoretical analysis were carried out to illustrate the failure mechanism of slope rock masses affected by earthquakes.The interaction between seismic waves and slope rock masses and the induced dynamic effect of slope rock masses were primarily accounted for in the analysis.The slope topography,rock mass weathering and unloading characteristics,river erosion,regional seismogenic structure,and rock mass structure characteristics were also discussed.The results showed that the formation of the Mogangling landslide was mainly related to the high amplification effect of seismic acceleration and back slope effects,interface dynamic stress effects,and double-sided slope effects of seismic waves caused by the catastrophic Ms 7.75 Moxi Earthquake in 1786.The principles for the site and route selection of large-scale infrastructure in the planning stage and the scientific prevention of seismic geological disasters were proposed on the basis of the dynamic effect of earthquake-induced landslides.展开更多
Effective Hamiltonians in periodically driven systems have received widespread attention for realization of novel quantum phases, non-equilibrium phase transition, and Majorana mode. Recently, the study of effective H...Effective Hamiltonians in periodically driven systems have received widespread attention for realization of novel quantum phases, non-equilibrium phase transition, and Majorana mode. Recently, the study of effective Hamiltonian using various methods has gained great interest. We consider a vector differential equation of motion to derive the effective Hamiltonian for any periodically driven two-level system, and the dynamics of the spin vector are an evolution under the Bloch sphere. Here, we investigate the properties of this equation and show that a sudden change of the effective Hamiltonian is expected. Furthermore, we present several exact relations, whose expressions are independent of the different starting points. Moreover, we deduce the effective Hamiltonian from the high-frequency limit, which approximately equals the results in previous studies. Our results show that the vector differential equation of motion is not affected by a convergence problem, and thus, can be used to numerically investigate the effective models in any periodic modulating system. Finally, we anticipate that the proposed method can be applied to experimental platforms that require time-periodic modulation, such as ultracold atoms and optical lattices.展开更多
We use linear entropy of an exact quantum state to study the entanglement between internal electronic states and external motional states for a two-level atom held in an amplitude-modulated and tilted optical lattice....We use linear entropy of an exact quantum state to study the entanglement between internal electronic states and external motional states for a two-level atom held in an amplitude-modulated and tilted optical lattice. Starting from an unentangled initial state associated with the regular ＇island＇ of classical phase space, it is demonstrated that the quantum resonance leads to entanglement generation, the chaotic parameter region results in the increase of the generation speed, and the symmetries of the initial probability distribution determine the final degree of entanglement. The entangled initial states are associated with the classical ＇chaotic sea＇, which do not affect the final entanglement degree for the same initial symmetry. The results may be useful in engineering quantum dynamics for quantum information processing.展开更多
Strict regulations on heavy metal(HM)limits impede the sludge land utilization for carbon emission reduction.This study aimed to evaluate the impact of bioavailable HMs(Cd,Cu,and Zn)on soil nitrification and determine...Strict regulations on heavy metal(HM)limits impede the sludge land utilization for carbon emission reduction.This study aimed to evaluate the impact of bioavailable HMs(Cd,Cu,and Zn)on soil nitrification and determine toxicity thresholds via two cycles of sludge land application tests over 185 days.HMs inhibited gene abundance in their labile fractions,with the most affected being nitrite-oxidizing bacteria(NOB)-nxrB,followed by ammonia-oxidizing bacteria(AOB)-amoA,NOB-nxrA,and ammonia oxidizing archaea(AOA)-amoA.Toxicity thresholds for incremental labile fractions of HMs(in mg/kg)were determined as 0.35 for Cd,21.73 for Cu,and 84.04 for Zn.Additionally,AOB,as the core nitrifiers,significantly correlated(P<0.05)with ammonia nitrogen,soil organic matter,total phosphorus,and total potassium,playing a pivotal role in maintaining intricate interactions within HMs-spiked sludge-treated soil systems.The acute toxicity effects of HMs on potential ammonia oxidation(PAO),measured by inhibition rates,were 77.04%,73.63%,and 67.06%for Cd,Cu,and Zn,with labile fractions contributing 33.79%,40.19%,and 28.37%,respectively.Long-term sludge land application revealed chronic toxicity of HMs to PAO through the reshaping of ammonia-oxidizing microorganisms,particularly Cu and Zn.These findings provide insights into HM toxicity thresholds and their impact on nitrification,supporting sustainable sludge land management.展开更多
We design dynamical Casimir arrays(DCA)consisting of giant atoms and coupled resonator waveguides(CRWs)to investigate the Einstein–Podolsky–Rosen(EPR)steering at finite temperatures.Our designed system exhibits an a...We design dynamical Casimir arrays(DCA)consisting of giant atoms and coupled resonator waveguides(CRWs)to investigate the Einstein–Podolsky–Rosen(EPR)steering at finite temperatures.Our designed system exhibits an asymmetry in its structure,which is caused by the differences in the sizes and the coupling positions of the giant atoms.The system achieves different types of EPR steering and the reversal of one-way EPR steering by modulating parameters.Furthermore,the symmetry and asymmetry of the system structure,in their responses to parameter modulation,both reveal the asymmetry of EPR steering.In this process,we discover that with the increase in temperature,different types of steering can be transferred from Casimir photons to giant atoms.We also achieve the monogamy of the multipartite system.These results provide important assistance for secure quantum communication,and further intuitively validating the asymmetry of EPR steering from multiple perspectives.展开更多
Seismicity resulting from the near-or in-field fault activation significantly affects the stability of large-scale underground caverns that are operating under high-stress conditions.A comprehensive scientific assessm...Seismicity resulting from the near-or in-field fault activation significantly affects the stability of large-scale underground caverns that are operating under high-stress conditions.A comprehensive scientific assessment of the operational safety of such caverns requires an in-depth understanding of the response characteristics of the rock mass subjected to dynamic disturbances.To address this issue,we conducted true triaxial modeling tests and dynamic numerical simulations on large underground caverns to investigate the impact of static stress levels,dynamic load parameters,and input directions on the response characteristics of the surrounding rock mass.The findings reveal that:(1)When subjected to identical incident stress waves and static loads,the surrounding rock mass exhibits the greatest stress response during horizontal incidence.When the incident direction is fixed,the mechanical response is more pronounced at the cavern wall parallel to the direction of dynamic loading.(2)A high initial static stress level specifically enhances the impact of dynamic loading.(3)The response of the surrounding rock mass is directly linked to the amplitude of the incident stress wave.High amplitude results in tensile damage in regions experiencing tensile stress concentration under static loading and shear damage in regions experiencing compressive stress concentration.These results have significant implications for the evaluation and prevention of dynamic disasters in the surrounding rock of underground caverns experiencing dynamic disturbances.展开更多
Steel strips are the main of steel products and flatness is an important quality indicator of steel strips. Flatness control is the key and highly difficult technique of strip mills. The bottle-neck restricting the im...Steel strips are the main of steel products and flatness is an important quality indicator of steel strips. Flatness control is the key and highly difficult technique of strip mills. The bottle-neck restricting the improvement of flatness control techniques is that the research on flatness theories and control mathematic models is not in accordance with the requirement of technique developments. To build a simple, rapid and accurate explicit formulation control model has become an urgent need for the development of flatness control technique. This paper puts forward the conception of dynamic effective matrix based on the effective matrix method for flatness control proposed by the authors under the consideration of the influence of the change of parameters in roiling processes on the effective matrix, and the concept is validated by industrial productions. Three methods of the effective matrix generation are induced： the calculation method based on the flatness prediction model; the calculation method based on the data excavation in rolling processes and the direct calculation method based on the network model. A fuzzy neural network effective matrix model is built based on the clusters, and then the network structure is optimized and the high-speed-calculation problem of the dynamic effective matrix is solved. The flatness control scheme for cold strip mills is proposed based on the dynamic effective matrix. On stand 5 of the 1 220 mm five-stand 4-high cold strip tandem mill, the industrial experiment with the control methods of tilting roll and bending roll is done by the control scheme of the static effective matrix and the dynamic effective matrix, respectively. The experiment result proves that the control effect of the dynamic effective matrix is much better than that of the static effective matrix. This paper proposes a new idea and method for the dynamic flatness control in the rolling processes of cold strip mills and develops the theory and model of the flatness control effective matrix method.展开更多
In the process of mining coalbed methane(CBM),an unsteady state often arises due to the rapid extraction,release and pressure relief of CBM.In this case,the effective stress of coal changes dynamically,affecting the s...In the process of mining coalbed methane(CBM),an unsteady state often arises due to the rapid extraction,release and pressure relief of CBM.In this case,the effective stress of coal changes dynamically,affecting the stability of the gassy coal seam.In this paper,gas release tests of gassy coal under conventional triaxial compression were performed,and the dynamic effective stress(DES)during gas release was obtained indirectly based on a constitutive equation and deformation of coal.The results show that the maximum increases in DES caused by the release of free gas and adsorbed gas under the stress of 1.1 MPa were 0.811 and 5.418 MPa,respectively,which seriously affected the stress state of the coal.During the gas release,the free gas pressure and the adsorbed gas volume were the parameters that directly affected the DES and showed a positive linear relationship with the DES with an intercept of zero.The DES of the coal sample increased exponentially with time,which was determined by the contents of free and adsorbed gas.Based on the experimental results and theoretical analysis,an effective stress model was obtained for loaded gassy coal during gas release.The results of verification indicated accuracy greater than 99%.展开更多
To compensate for the shortcomings of quasi-static law in anti-fatigue analysis of foundry crane metal structures,the fatigue life evaluation method of foundry crane metal structure considering load dynamic response a...To compensate for the shortcomings of quasi-static law in anti-fatigue analysis of foundry crane metal structures,the fatigue life evaluation method of foundry crane metal structure considering load dynamic response and crack closure effect is proposed.In line with the theory of mechanical vibration,a dynamic model of crane structure during the working cycle is constructed,and dynamic coefficients under diverse actions are analysed.Calculation models of the internal force dynamic change process of dangerous cross-sections and a simulation model of first principal stress-time history are established by using the steel structure design criteria,which is utilised to extract the change of first principal stress of danger points over time.Then,the double-parameter stress spectrum is obtained by the rain flow counting method.The fatigue life calculation formula is corrected by introducing a crack closure parameter that can be calculated by the stress ratio and the effective stress ratio.Under the finite element model imported into Msc.Patran,crack propagation analysis is performed by the growth method in the fatigue integration module Msc.Fatigue.Taking the metal structure of a 100/40t-28.5m foundry crane with track offset as an example,the accuracy of calculation results and the feasibility and applicability of the proposed method are verified by theoretical calculation and finite element simulation,which provide a theoretical basis for improvement of the fatigue resistance design of foundry cranes.展开更多
The frequency-dependent dynamic effective properties (phase velocity, attenuation and elastic modulus) of porous materials are studied numerically. The coherent plane longitudinal and shear wave equations, which are o...The frequency-dependent dynamic effective properties (phase velocity, attenuation and elastic modulus) of porous materials are studied numerically. The coherent plane longitudinal and shear wave equations, which are obtained by averaging on the multiple scattering fields, are used to evaluate the frequency-dependent dynamic effective properties of a porous material. It is found that the prediction of the dynamic effective properties includes the size effects of voids which are not included in most prediction of the traditional static effective properties. The prediction of the dynamic effective elastic modulus at a relatively low frequency range is compared with that of the traditional static effective elastic modulus, and the dynamic effective elastic modulus is found to be very close to the Hashin-Shtrikman upper bound.展开更多
The relationship between capillary pressure and saturation plays a critical role in the characterization of two-phase flow and transport in aquifers and oil reservoirs. This relationship is usually determined under th...The relationship between capillary pressure and saturation plays a critical role in the characterization of two-phase flow and transport in aquifers and oil reservoirs. This relationship is usually determined under the static condition, where capillary pressure is the only function of saturation. However,considerable experiments have suggested that the dependence of capillary pressure on desaturation rate is under the dynamic condition. Thus, a more general description of capillary pressure that includes dynamic capillary effect has been approved widely. A comprehensive understanding of the dynamic capillary effect is needed for the investigation of the two-phase flow in porous media by various methods. In general, dynamic capillary effect in porous media can be studied through the laboratory experiment, pore-to macro-scale modeling, and artificial neural network. Here, main principle and research procedures of each method are reviewed in detail. Then, research progress, disadvantages and advantages are discussed, respectively. In addition, upscaling study from pore-to macro-scale are introduced, which explains the difference between laboratory experiment and pore-scale modeling. At last, several future perspectives and recommendations for optimal solution of dynamic capillary effect are presented.展开更多
According to the results of experiments and theoretical analysis, a phenomenon called ＂capture effect＂ is put forward, which could be used to describe the particles dynamic behavior of electrorheological （ER） susp...According to the results of experiments and theoretical analysis, a phenomenon called ＂capture effect＂ is put forward, which could be used to describe the particles dynamic behavior of electrorheological （ER） suspensions. Then a ＂structure-force＂ mathematical model is established to explain this effect based on electrostatic energy density equation. The analysis results show that the dynamic coupling process of ER suspensions under an external electric filed is the function not only of the electric intensity, but also of the dielectric properties and the structure form.展开更多
Based on the characteristics of the top coal thickness of the fully mechanized caving in special thick coal seam,the long distance of coal gangue caving,as well as the different sizes of the coal gangue broken fragmen...Based on the characteristics of the top coal thickness of the fully mechanized caving in special thick coal seam,the long distance of coal gangue caving,as well as the different sizes of the coal gangue broken fragment dimension and spatial variation of drop flow,this paper uses laboratory dispersion simulation experiment and theoretical analysis to study the arch structure effect and its influence rule on the top coal loss in the process of coal gangue flow.Research shows that in the process of coal gangue flow,arch structure can be formed in three types:the lower arch structure,middle arch structure,and upper arch structure.Moreover,the arch structure has the characteristics of dynamic random arch,the formation probability of dynamic random arch with different layers is not the same,dynamic random arch caused the reduction of the top coal fluency;analyzing the dynamic random arch formation mechanism,influencing factors,and the conditions of instability;the formation probability of the lower arch structure is the highest,the whole coal arch and the coal gangue arch structure has the greatest impact on top coal loss.Therefore,to prevent or reduce the formation of lower whole coal arch structure,the lower coal gangue arch structure and the middle whole coal arch structure is the key to reduce the top coal loss.The research conclusion provides theoretical basis for the further improvement of the top coal recovery rate of the fully mechanized caving in extra thick coal seam.展开更多
In order to study the effect of dynamic recrystallization on the metal flow behavior during thermal deformation,the elevated temperature compression experiments of CuCrZr alloy and 35CrMo steel are carried out using G...In order to study the effect of dynamic recrystallization on the metal flow behavior during thermal deformation,the elevated temperature compression experiments of CuCrZr alloy and 35CrMo steel are carried out using Gleeble-3810 thermal simulator.It is proved that the samples underwent obvious dynamic recrystallization behavior during thermal deformation by microstructure observation of deformed specimens.The size of recrystallized grains increases as the temperature improved and the strain rate decreased.Meanwhile,the net softening rate caused by dynamic recrystallization is determined based on the stress-dislocation relationship.It can be found that the value of net softening rate increases quadratically as the Z parameter decreases,and the dynamic recrystallization net softening rate of CuCrZr alloy and 35CrMo steel are calculated to be 21.9%and 29.8%,respectively.Based on the dynamic recrystallization softening effect proposed,the novel elevated temperature flow constitutive models of two different alloys are proposed,and the related parameters are well defined and solved in detail.The predicted values of the obtained models are agreed well with the experimental values.展开更多
We investigate the effects of dynamical Casimir effect in superradiant light scattering by Bose-Einstein condensate in an optomechanical cavity. The system is studied using both classical and quantized mirror motions....We investigate the effects of dynamical Casimir effect in superradiant light scattering by Bose-Einstein condensate in an optomechanical cavity. The system is studied using both classical and quantized mirror motions. The cavity frequency is harmonically modulated in time for both the cases. The main quantity of interest is the number of intracavity scattered photons. The system has been investigated under the weak and strong modulations. It has been observed that the amplitude of the scattered photons is more for the classical mirror motion than the quantized mirror motion. Also, initially, the amplitude of scattered photons is high for lower modulation amplitude than higher modulation amplitude. We also found that the behavior of the plots are similar under strong and weak modulations for the quantized mirror motion.展开更多
Mine gas extraction in China is difficult due to the characteristics such as micro-porosity,low-permeability and high adsorption of coal seams.The pulsed mechanismof a high-pressure pulsed water jet was studied throug...Mine gas extraction in China is difficult due to the characteristics such as micro-porosity,low-permeability and high adsorption of coal seams.The pulsed mechanismof a high-pressure pulsed water jet was studied through theoretical analysis,experimentand field measurement.The results show that high-pressure pulsed water jet has threedynamic properties.What's more,the three dynamic effects can be found in low-permeabilitycoal seams.A new pulsed water jet with 200-1 000 Hz oscillation frequency andpeak pressure 2.5 times than average pressure was introduced.During bubble collapsing,sound vibration and instantaneous high pressures over 100 MPa enhanced the cuttingability of the high-pressure jet.Through high-pressure pulsed water jet drilling and slotting,the exposure area of coal bodies was greatly enlarged and pressure of the coal seamsrapidly decreased.Therefore,the permeability of coal seams was improved and gas absorptionrate also decreased.Application results show that gas adsorption rate decreasedby 30%-40%and the penetrability coefficient increased 100 times.This proves that high-pressurepulsed water is more efficient than other conventional methods.展开更多
文摘We consider matter-wave solitons in spin-orbit coupled Bose-Einstein condensates embedded in an optical lattice and study the dynamics of the soliton within the framework of Gross-Pitaevskii equations.We express spin components of the soliton pair in terms of nonlinear Bloch equations and investigate the effective spin dynamics.It is seen that the effective magnetic field that appears in the Bloch equation is affected by optical lattices,and thus the optical lattice influences the precessional frequency of the spin components.We make use of numerical approaches to investigate the dynamical behavior of density profiles and center-of-mass of the soliton pair in the presence of the optical lattice.It is shown that the spin density is periodically varying due to flipping of spinors between the two states.The amplitude of spin-flipping oscillation increases with lattice strength.We find that the system can also exhibit interesting nonlinear behavior for chosen values of parameters.We present a fixed point analysis to study the effects of optical lattices on the nonlinear dynamics of the spin components.It is seen that the optical lattice can act as a control parameter to change the dynamical behavior of the spin components from periodic to chaotic.
基金supported by the National Natural Science Foundation of China(Grant No.51678490)the Natural Science Foundation of Sichuan Province(Grant No.2024NSFSC0161).
文摘Railway bridges are continuously loaded by railway trains;therefore, it is important to understand the nonlinear seismic response of the Vehicle-Bridge Interaction (VBI) system under strong earthquakes. For this purpose, the nonlinear behavior of the pier was introduced into the in-house VBI solvers. The nonlinear the seismic response of the VBI system was comprehensively evaluated using this model, and the effect of the vehicle dynamics on seismic performance of the bridge was identified. It was found that the seismic responses of most simply-supported bridges were reduced in the presence of railway trains due to the out-of-phase motion of the vehicle-bridge system. Meanwhile, the nonlinear behavior of the pier can reduce the vehicle’s seismic responses. Therefore, ignoring the nonlinear behavior of the pier during strong earthquakes can significantly overestimate the seismic response of the vehicle.
基金supported by NSF of China (10901065, 10971225, and11028102)the NSF Grants 1025422 and 0731201the Cheung Kong Scholars Program, and an open research grant from the State Key Laboratory for Nonlinear Mechanics at the Chinese Academy of Sciences
文摘A conceptual model for microscopic-macroscopic slow-fast stochastic systems is considered. A dynamical reduction procedure is presented in order to extract effective dynamics for this kind of systems. Under appropriate assumptions, the effective system is shown to approximate the original system, in the sense of a probabilistic convergence.
文摘The dynamics of blood lead (Pb-B) and blood zinc protoporphyrin (ZPP-B) of women in early pregnancy and parturient women with lead exposure and the effects on fetus development were investigated. Pb-B of lead-exposed women was high: 0.984 μmol/L (20.38 μg/dl) and ZPP was 84.52μg/dl. Cord blood Pb-B was 0.896 μmol/L(18.56μg/dl)and cord blood ZPP was 69.24μg/dl. In the control group, Pb-B was 0.261μmol/L(5.41μg/dl), ZPP-B, 37.59 μg/dl, cord blood, Pb-B 0.34 μmol/L (7.93 μg/dl), and cord ZPP-B 49.0μg/dl. There was a significant correlation between blood lead and blood ZPP, maternal Pb-B and cord Pb-B, maternal Pb-B and cord ZPP-B. The significance of the consistency of high level Pb-B and the effects on fetus development is discussed.
基金supported by the China Geological Survey Projects(Nos.20160272,20211379)the Second Tibetan Plateau Scientific Expedition and Research Program(No.2019QZKK0904)。
文摘The dynamic effect is a very important issue widely debated by scholars when studying the genetic and disaster-causing mechanisms of earthquake-triggered landslides.First,the dynamic effect mechanism and phenomena of earthquake-triggered landslides were summarized in this paper.Then,the primary types of dynamic effects were further used to interpret the Mogangling landslide in Moxi Town of Luding County,China.A field investigation,remote sensing,numerical calculation and theoretical analysis were carried out to illustrate the failure mechanism of slope rock masses affected by earthquakes.The interaction between seismic waves and slope rock masses and the induced dynamic effect of slope rock masses were primarily accounted for in the analysis.The slope topography,rock mass weathering and unloading characteristics,river erosion,regional seismogenic structure,and rock mass structure characteristics were also discussed.The results showed that the formation of the Mogangling landslide was mainly related to the high amplification effect of seismic acceleration and back slope effects,interface dynamic stress effects,and double-sided slope effects of seismic waves caused by the catastrophic Ms 7.75 Moxi Earthquake in 1786.The principles for the site and route selection of large-scale infrastructure in the planning stage and the scientific prevention of seismic geological disasters were proposed on the basis of the dynamic effect of earthquake-induced landslides.
基金supported by the National Natural Science Foundation of China (Grant No. 11774328)。
文摘Effective Hamiltonians in periodically driven systems have received widespread attention for realization of novel quantum phases, non-equilibrium phase transition, and Majorana mode. Recently, the study of effective Hamiltonian using various methods has gained great interest. We consider a vector differential equation of motion to derive the effective Hamiltonian for any periodically driven two-level system, and the dynamics of the spin vector are an evolution under the Bloch sphere. Here, we investigate the properties of this equation and show that a sudden change of the effective Hamiltonian is expected. Furthermore, we present several exact relations, whose expressions are independent of the different starting points. Moreover, we deduce the effective Hamiltonian from the high-frequency limit, which approximately equals the results in previous studies. Our results show that the vector differential equation of motion is not affected by a convergence problem, and thus, can be used to numerically investigate the effective models in any periodic modulating system. Finally, we anticipate that the proposed method can be applied to experimental platforms that require time-periodic modulation, such as ultracold atoms and optical lattices.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11175064 and 11475060the Construct Program of the National Key Discipline of Chinathe Hunan Provincial Innovation Foundation for Postgraduates under Grant No CX2014B195
文摘We use linear entropy of an exact quantum state to study the entanglement between internal electronic states and external motional states for a two-level atom held in an amplitude-modulated and tilted optical lattice. Starting from an unentangled initial state associated with the regular ＇island＇ of classical phase space, it is demonstrated that the quantum resonance leads to entanglement generation, the chaotic parameter region results in the increase of the generation speed, and the symmetries of the initial probability distribution determine the final degree of entanglement. The entangled initial states are associated with the classical ＇chaotic sea＇, which do not affect the final entanglement degree for the same initial symmetry. The results may be useful in engineering quantum dynamics for quantum information processing.
基金received support from the National Key Research and Development Program of China(No.2023YFC3207404)the National Natural Science Foundation of China(No.52270034)+1 种基金funding was provided by the National Engineering Research Center for Safe Sludge Disposal and Resource Recovery(No.2021A004)the National Engineering Research Center for Bioenergy(No.2021B007).
文摘Strict regulations on heavy metal(HM)limits impede the sludge land utilization for carbon emission reduction.This study aimed to evaluate the impact of bioavailable HMs(Cd,Cu,and Zn)on soil nitrification and determine toxicity thresholds via two cycles of sludge land application tests over 185 days.HMs inhibited gene abundance in their labile fractions,with the most affected being nitrite-oxidizing bacteria(NOB)-nxrB,followed by ammonia-oxidizing bacteria(AOB)-amoA,NOB-nxrA,and ammonia oxidizing archaea(AOA)-amoA.Toxicity thresholds for incremental labile fractions of HMs(in mg/kg)were determined as 0.35 for Cd,21.73 for Cu,and 84.04 for Zn.Additionally,AOB,as the core nitrifiers,significantly correlated(P<0.05)with ammonia nitrogen,soil organic matter,total phosphorus,and total potassium,playing a pivotal role in maintaining intricate interactions within HMs-spiked sludge-treated soil systems.The acute toxicity effects of HMs on potential ammonia oxidation(PAO),measured by inhibition rates,were 77.04%,73.63%,and 67.06%for Cd,Cu,and Zn,with labile fractions contributing 33.79%,40.19%,and 28.37%,respectively.Long-term sludge land application revealed chronic toxicity of HMs to PAO through the reshaping of ammonia-oxidizing microorganisms,particularly Cu and Zn.These findings provide insights into HM toxicity thresholds and their impact on nitrification,supporting sustainable sludge land management.
基金Project supported by the Education Department of Jilin Province,China(Grant No.JJKH20231291KJ)。
文摘We design dynamical Casimir arrays(DCA)consisting of giant atoms and coupled resonator waveguides(CRWs)to investigate the Einstein–Podolsky–Rosen(EPR)steering at finite temperatures.Our designed system exhibits an asymmetry in its structure,which is caused by the differences in the sizes and the coupling positions of the giant atoms.The system achieves different types of EPR steering and the reversal of one-way EPR steering by modulating parameters.Furthermore,the symmetry and asymmetry of the system structure,in their responses to parameter modulation,both reveal the asymmetry of EPR steering.In this process,we discover that with the increase in temperature,different types of steering can be transferred from Casimir photons to giant atoms.We also achieve the monogamy of the multipartite system.These results provide important assistance for secure quantum communication,and further intuitively validating the asymmetry of EPR steering from multiple perspectives.
基金supported by the National Natural Science Foundation of China (Grant No.52279116)the Key Projects of the Yalong River Joint Fund of the National Natural Science Foundation of China (Grant No.U1865203).
文摘Seismicity resulting from the near-or in-field fault activation significantly affects the stability of large-scale underground caverns that are operating under high-stress conditions.A comprehensive scientific assessment of the operational safety of such caverns requires an in-depth understanding of the response characteristics of the rock mass subjected to dynamic disturbances.To address this issue,we conducted true triaxial modeling tests and dynamic numerical simulations on large underground caverns to investigate the impact of static stress levels,dynamic load parameters,and input directions on the response characteristics of the surrounding rock mass.The findings reveal that:(1)When subjected to identical incident stress waves and static loads,the surrounding rock mass exhibits the greatest stress response during horizontal incidence.When the incident direction is fixed,the mechanical response is more pronounced at the cavern wall parallel to the direction of dynamic loading.(2)A high initial static stress level specifically enhances the impact of dynamic loading.(3)The response of the surrounding rock mass is directly linked to the amplitude of the incident stress wave.High amplitude results in tensile damage in regions experiencing tensile stress concentration under static loading and shear damage in regions experiencing compressive stress concentration.These results have significant implications for the evaluation and prevention of dynamic disasters in the surrounding rock of underground caverns experiencing dynamic disturbances.
基金supported by National Natural Science Foundation of China(Grant No. 50675186)Hebei Provincial Major Natural Science Foundation of China (Grant No. E2006001038)
文摘Steel strips are the main of steel products and flatness is an important quality indicator of steel strips. Flatness control is the key and highly difficult technique of strip mills. The bottle-neck restricting the improvement of flatness control techniques is that the research on flatness theories and control mathematic models is not in accordance with the requirement of technique developments. To build a simple, rapid and accurate explicit formulation control model has become an urgent need for the development of flatness control technique. This paper puts forward the conception of dynamic effective matrix based on the effective matrix method for flatness control proposed by the authors under the consideration of the influence of the change of parameters in roiling processes on the effective matrix, and the concept is validated by industrial productions. Three methods of the effective matrix generation are induced： the calculation method based on the flatness prediction model; the calculation method based on the data excavation in rolling processes and the direct calculation method based on the network model. A fuzzy neural network effective matrix model is built based on the clusters, and then the network structure is optimized and the high-speed-calculation problem of the dynamic effective matrix is solved. The flatness control scheme for cold strip mills is proposed based on the dynamic effective matrix. On stand 5 of the 1 220 mm five-stand 4-high cold strip tandem mill, the industrial experiment with the control methods of tilting roll and bending roll is done by the control scheme of the static effective matrix and the dynamic effective matrix, respectively. The experiment result proves that the control effect of the dynamic effective matrix is much better than that of the static effective matrix. This paper proposes a new idea and method for the dynamic flatness control in the rolling processes of cold strip mills and develops the theory and model of the flatness control effective matrix method.
基金This research was funded by the National Natural Science Foundation of China(No.52174081)the China Postdoctoral Science Foundation(No.2021M702001)+1 种基金the Postdoctoral Innovation Project of Shandong Province(No.202102002)the Natural Science Foundation of Shandong Province(No.2019GSF111036).
文摘In the process of mining coalbed methane(CBM),an unsteady state often arises due to the rapid extraction,release and pressure relief of CBM.In this case,the effective stress of coal changes dynamically,affecting the stability of the gassy coal seam.In this paper,gas release tests of gassy coal under conventional triaxial compression were performed,and the dynamic effective stress(DES)during gas release was obtained indirectly based on a constitutive equation and deformation of coal.The results show that the maximum increases in DES caused by the release of free gas and adsorbed gas under the stress of 1.1 MPa were 0.811 and 5.418 MPa,respectively,which seriously affected the stress state of the coal.During the gas release,the free gas pressure and the adsorbed gas volume were the parameters that directly affected the DES and showed a positive linear relationship with the DES with an intercept of zero.The DES of the coal sample increased exponentially with time,which was determined by the contents of free and adsorbed gas.Based on the experimental results and theoretical analysis,an effective stress model was obtained for loaded gassy coal during gas release.The results of verification indicated accuracy greater than 99%.
基金the National Science-technology Support Projects for the 13th Five-year Plan(2017YFC0805703-4).
文摘To compensate for the shortcomings of quasi-static law in anti-fatigue analysis of foundry crane metal structures,the fatigue life evaluation method of foundry crane metal structure considering load dynamic response and crack closure effect is proposed.In line with the theory of mechanical vibration,a dynamic model of crane structure during the working cycle is constructed,and dynamic coefficients under diverse actions are analysed.Calculation models of the internal force dynamic change process of dangerous cross-sections and a simulation model of first principal stress-time history are established by using the steel structure design criteria,which is utilised to extract the change of first principal stress of danger points over time.Then,the double-parameter stress spectrum is obtained by the rain flow counting method.The fatigue life calculation formula is corrected by introducing a crack closure parameter that can be calculated by the stress ratio and the effective stress ratio.Under the finite element model imported into Msc.Patran,crack propagation analysis is performed by the growth method in the fatigue integration module Msc.Fatigue.Taking the metal structure of a 100/40t-28.5m foundry crane with track offset as an example,the accuracy of calculation results and the feasibility and applicability of the proposed method are verified by theoretical calculation and finite element simulation,which provide a theoretical basis for improvement of the fatigue resistance design of foundry cranes.
基金This work was financially supported by the National Natural Science Foundation of China (No.10272003, No. 10032010, and No. 10372004) the Talent Foundation of the University of Sciences and Technology Beijing.
文摘The frequency-dependent dynamic effective properties (phase velocity, attenuation and elastic modulus) of porous materials are studied numerically. The coherent plane longitudinal and shear wave equations, which are obtained by averaging on the multiple scattering fields, are used to evaluate the frequency-dependent dynamic effective properties of a porous material. It is found that the prediction of the dynamic effective properties includes the size effects of voids which are not included in most prediction of the traditional static effective properties. The prediction of the dynamic effective elastic modulus at a relatively low frequency range is compared with that of the traditional static effective elastic modulus, and the dynamic effective elastic modulus is found to be very close to the Hashin-Shtrikman upper bound.
基金financially supported by the National Natural Science Foundation of China (No. 42102149)the Fundamental Research Funds for the Central Universities (No. 2462021YXZZ005)。
文摘The relationship between capillary pressure and saturation plays a critical role in the characterization of two-phase flow and transport in aquifers and oil reservoirs. This relationship is usually determined under the static condition, where capillary pressure is the only function of saturation. However,considerable experiments have suggested that the dependence of capillary pressure on desaturation rate is under the dynamic condition. Thus, a more general description of capillary pressure that includes dynamic capillary effect has been approved widely. A comprehensive understanding of the dynamic capillary effect is needed for the investigation of the two-phase flow in porous media by various methods. In general, dynamic capillary effect in porous media can be studied through the laboratory experiment, pore-to macro-scale modeling, and artificial neural network. Here, main principle and research procedures of each method are reviewed in detail. Then, research progress, disadvantages and advantages are discussed, respectively. In addition, upscaling study from pore-to macro-scale are introduced, which explains the difference between laboratory experiment and pore-scale modeling. At last, several future perspectives and recommendations for optimal solution of dynamic capillary effect are presented.
文摘According to the results of experiments and theoretical analysis, a phenomenon called ＂capture effect＂ is put forward, which could be used to describe the particles dynamic behavior of electrorheological （ER） suspensions. Then a ＂structure-force＂ mathematical model is established to explain this effect based on electrostatic energy density equation. The analysis results show that the dynamic coupling process of ER suspensions under an external electric filed is the function not only of the electric intensity, but also of the dielectric properties and the structure form.
基金the Independent Research Subject of State Key Laboratory of Coal Resources and Mine Safety of China University of Mining and Technology (No.SKLCRSM12X03)the Scientific Research and Innovation Project for College Graduates in Jiangsu (No.CXZZ13_0947)+1 种基金Top-Notch Academic Programs of Jiangsu Higher Education Institutionsthe Priority Academic Development Program of Jiangsu Higher Education Institutions
文摘Based on the characteristics of the top coal thickness of the fully mechanized caving in special thick coal seam,the long distance of coal gangue caving,as well as the different sizes of the coal gangue broken fragment dimension and spatial variation of drop flow,this paper uses laboratory dispersion simulation experiment and theoretical analysis to study the arch structure effect and its influence rule on the top coal loss in the process of coal gangue flow.Research shows that in the process of coal gangue flow,arch structure can be formed in three types:the lower arch structure,middle arch structure,and upper arch structure.Moreover,the arch structure has the characteristics of dynamic random arch,the formation probability of dynamic random arch with different layers is not the same,dynamic random arch caused the reduction of the top coal fluency;analyzing the dynamic random arch formation mechanism,influencing factors,and the conditions of instability;the formation probability of the lower arch structure is the highest,the whole coal arch and the coal gangue arch structure has the greatest impact on top coal loss.Therefore,to prevent or reduce the formation of lower whole coal arch structure,the lower coal gangue arch structure and the middle whole coal arch structure is the key to reduce the top coal loss.The research conclusion provides theoretical basis for the further improvement of the top coal recovery rate of the fully mechanized caving in extra thick coal seam.
基金Project(2019zzts525)supported by the Fundamental Research Funds for the Central Universities,ChinaProjects(U1837207,U1637601)supported by the National Natural Science Foundation of China
文摘In order to study the effect of dynamic recrystallization on the metal flow behavior during thermal deformation,the elevated temperature compression experiments of CuCrZr alloy and 35CrMo steel are carried out using Gleeble-3810 thermal simulator.It is proved that the samples underwent obvious dynamic recrystallization behavior during thermal deformation by microstructure observation of deformed specimens.The size of recrystallized grains increases as the temperature improved and the strain rate decreased.Meanwhile,the net softening rate caused by dynamic recrystallization is determined based on the stress-dislocation relationship.It can be found that the value of net softening rate increases quadratically as the Z parameter decreases,and the dynamic recrystallization net softening rate of CuCrZr alloy and 35CrMo steel are calculated to be 21.9%and 29.8%,respectively.Based on the dynamic recrystallization softening effect proposed,the novel elevated temperature flow constitutive models of two different alloys are proposed,and the related parameters are well defined and solved in detail.The predicted values of the obtained models are agreed well with the experimental values.
文摘We investigate the effects of dynamical Casimir effect in superradiant light scattering by Bose-Einstein condensate in an optomechanical cavity. The system is studied using both classical and quantized mirror motions. The cavity frequency is harmonically modulated in time for both the cases. The main quantity of interest is the number of intracavity scattered photons. The system has been investigated under the weak and strong modulations. It has been observed that the amplitude of the scattered photons is more for the classical mirror motion than the quantized mirror motion. Also, initially, the amplitude of scattered photons is high for lower modulation amplitude than higher modulation amplitude. We also found that the behavior of the plots are similar under strong and weak modulations for the quantized mirror motion.
基金Supported by the National Natural Science Foundation of China(50604019)the Innovation Team Foundation of China(50621403)
文摘Mine gas extraction in China is difficult due to the characteristics such as micro-porosity,low-permeability and high adsorption of coal seams.The pulsed mechanismof a high-pressure pulsed water jet was studied through theoretical analysis,experimentand field measurement.The results show that high-pressure pulsed water jet has threedynamic properties.What's more,the three dynamic effects can be found in low-permeabilitycoal seams.A new pulsed water jet with 200-1 000 Hz oscillation frequency andpeak pressure 2.5 times than average pressure was introduced.During bubble collapsing,sound vibration and instantaneous high pressures over 100 MPa enhanced the cuttingability of the high-pressure jet.Through high-pressure pulsed water jet drilling and slotting,the exposure area of coal bodies was greatly enlarged and pressure of the coal seamsrapidly decreased.Therefore,the permeability of coal seams was improved and gas absorptionrate also decreased.Application results show that gas adsorption rate decreasedby 30%-40%and the penetrability coefficient increased 100 times.This proves that high-pressurepulsed water is more efficient than other conventional methods.
