In order to achieve the complex dynamic analysis of the self-propelled seafloor pilot miner moving on the seafloor of extremely cohesive soft soil and further to make it possible to integrate the miner system with som...In order to achieve the complex dynamic analysis of the self-propelled seafloor pilot miner moving on the seafloor of extremely cohesive soft soil and further to make it possible to integrate the miner system with some subsystems to form the complete integrated deep ocean mining pilot system and perform dynamic analysis, a new method for the dynamic modeling and analysis of the miner is proposed and developed in this paper, resulting in a simplified 3D single-body vehicle model with three translational and three rotational degrees of freedom, while the track-terrain interaction model is built by partitioning the track-terrain interface into discrete elements with parameterized force dements built on the theory of terramechanics acting on each discrete dement. To evaluate and verify the correctness and effectiveness of this new modeling and analysis method, typical comparative studies with regard to computational efficiency and solution accuracy are carried out between the traditional modeling method of building the tracked vehicle as a multi-body model and the new modeling method. In full consideration of the particMar structure design of the pilot miner, the special characteristics of the seafioor soil and the hydrodynamic force of near-seafloor currnt, the dynamic simulation analysis of the miner is performed and discussed, which can provide useful guidance and reference for the practical miner system in design and operation. This new method can not only realize the rapid dynamic simulation analysis of the miner but also make possible the integration and rapid dynamic analysis of the complete integrated deep ocean mining pilot system in further researches.展开更多
The modified Korteweg-de Vries （mKdV） typed equations can be used to describe certain nonlinear phenomena in fluids, plasmas, and optics. In this paper, the discretized mKdV lattice equation is investigated. With th...The modified Korteweg-de Vries （mKdV） typed equations can be used to describe certain nonlinear phenomena in fluids, plasmas, and optics. In this paper, the discretized mKdV lattice equation is investigated. With the aid of symbolic computation, the discrete matrix spectral problem for that system is constructed. Darboux transformation for that system is established based on the resulting spectral problem. Explicit solutions are derived via the Darboux transformation. Structures of those solutions are shown graphically, which might be helpful to understand some physical processes in fluids, plasmas, and optics.展开更多
In this letter, we study discretized mKdV lattice equation by using a new generalized ansatz. As a result,many explicit rational exact solutions, including some new solitary wave solutions, are obtained by symbolic co...In this letter, we study discretized mKdV lattice equation by using a new generalized ansatz. As a result,many explicit rational exact solutions, including some new solitary wave solutions, are obtained by symbolic computation code Maple.展开更多
For nonlinear stability problems of discretized conservative systems with multiple parameter variables and multiple state variables, the activation method is put forward, by which activated potential functions and act...For nonlinear stability problems of discretized conservative systems with multiple parameter variables and multiple state variables, the activation method is put forward, by which activated potential functions and activated equilibrium equations are derived. The activation method is the improvement and enhancement of Liapunov-Schmidt method in elastic stability theory. It is more generalized and more normalized than conventional perturbation methods. The activated potential functions may be transformed into normalized catastrophe potential functions. The activated equilibrium equations may be treated as bifurcation equations. The researches in this paper will motivate the combination of elastic stability theory with catastrophe theory and bifurcation theory展开更多
The rock fragmentation involves the inter-block and the intra-block fracture.A simulation method for rock fragmentation is developed by coupling Voronoi diagram(VD)and discretized virtual internal bond(DVIB).The DVIB ...The rock fragmentation involves the inter-block and the intra-block fracture.A simulation method for rock fragmentation is developed by coupling Voronoi diagram(VD)and discretized virtual internal bond(DVIB).The DVIB is a lattice model that consists of bonds.The VD is used to generate the potential block structure in the DVIB mesh.Each potential block may contain any number of bond cells.To characterize the inter-block fracture,a hyperelastic bond potential is employed for the bond cells that are cut by the VD edges.While to characterize the intra-block fracture,an elastobrittle bond potential is adopted for the bonds in a block.By this method,both the inter-block and intra-block fracture can be well simulated.The simulation results suggest that this method is a simple and efficient approach to rock fragmentation simulation with block smash.展开更多
This paper focuses on the robust stability for time-delay systems of neutral type. A new complete Lyapunov-Krasovskii function (LKF) is developed. Based on this function and discretization, stability conditions in ter...This paper focuses on the robust stability for time-delay systems of neutral type. A new complete Lyapunov-Krasovskii function (LKF) is developed. Based on this function and discretization, stability conditions in terms of linear matrix inequalities are obtained. A class of time-varying uncertainty of system matrices can be studied by the method.展开更多
Discrete software reliability measurement has a proper characteristic for describing a software reliability growth process which depends on a unit of the software fault-detection period, such as the number of test run...Discrete software reliability measurement has a proper characteristic for describing a software reliability growth process which depends on a unit of the software fault-detection period, such as the number of test runs, the number of executed test cases. This paper discusses discrete software reliability measurement based on a discretized nonhomogeneous Poisson process (NHPP) model. Especially, we use a bootstrapping method in our discrete software reliability measurement for discussing the statistical inference on parameters and software reliability assessment measures of our model. Finally we show numerical examples of interval estimations based on our bootstrapping method for the several software reliability assessment measures by using actual data.展开更多
The complex structure and strong heterogeneity of advanced nuclear reactor systems pose challenges for high-fidelity neutron-shielding calculations. Unstructured meshes exhibit strong geometric adaptability and can ov...The complex structure and strong heterogeneity of advanced nuclear reactor systems pose challenges for high-fidelity neutron-shielding calculations. Unstructured meshes exhibit strong geometric adaptability and can overcome the deficiencies of conventionally structured meshes in complex geometry modeling. A multithreaded parallel upwind sweep algorithm for S_(N) transport was proposed to achieve a more accurate geometric description and improve the computational efficiency. The spatial variables were discretized using the standard discontinuous Galerkin finite-element method. The angular flux transmission between neighboring meshes was handled using an upwind scheme. In addition, a combination of a mesh transport sweep and angular iterations was realized using a multithreaded parallel technique. The algorithm was implemented in the 2D/3D S_(N) transport code ThorSNIPE, and numerical evaluations were conducted using three typical benchmark problems:IAEA, Kobayashi-3i, and VENUS-3. These numerical results indicate that the multithreaded parallel upwind sweep algorithm can achieve high computational efficiency. ThorSNIPE, with a multithreaded parallel upwind sweep algorithm, has good reliability, stability, and high efficiency, making it suitable for complex shielding calculations.展开更多
In this paper, a discretized SIR model with pulse vaccination and time delay is proposed. We introduce two thresholds R* and R<sub>*</sub>, and further prove that the disease-free periodic solution is glob...In this paper, a discretized SIR model with pulse vaccination and time delay is proposed. We introduce two thresholds R* and R<sub>*</sub>, and further prove that the disease-free periodic solution is globally attractive if R* is less than unit and the disease can invade if R<sub>*</sub> is larger than unit. The numerical simulations not only illustrate the validity of our main results, but also exhibit bifurcation phenomenon. Our result shows that decreasing infection rate can put off the disease outbreak and reduce the number of infected individuals.展开更多
This paper presents an Euler discretized inertial delayed neuron model, and its bifurcation dynamical behaviors are discussed. By using the associated characteristic model, center manifold theorem and the normal form ...This paper presents an Euler discretized inertial delayed neuron model, and its bifurcation dynamical behaviors are discussed. By using the associated characteristic model, center manifold theorem and the normal form method, it is shown that the model not only undergoes codimension one(flip, Neimark-Sacker) bifurcation, but also undergoes cusp and resonance bifurcation(1:1 and 1:2) of codimension two. Further, it is found that the parity of delay has some effect on bifurcation behaviors. Finally, some numerical simulations are given to support the analytic results and explore complex dynamics, such as periodic orbits near homoclinic orbits, quasiperiodic orbits, and chaotic orbits.展开更多
We present a systematic study of 6Li elastic scattering and total reaction cross sections at incident energies around the Coulomb barrier within the continuum discretized coupled-channels(CDCC)framework,where 6Li is t...We present a systematic study of 6Li elastic scattering and total reaction cross sections at incident energies around the Coulomb barrier within the continuum discretized coupled-channels(CDCC)framework,where 6Li is treated in anα+d two-body model.Collisions with 27Al,64Zn,138Ba,and 208Pa are analyzed.The microscopic optical potentials(MOP)based on Skyrme nucleon-nucleon interaction forαand d are adopted in CDCC calculations and satisfactory agreement with the experimental data is obtained without any adjustment on MOPs.For comparison,αand d global phenomenological optical potentials(GOP)are also used in CDCC analysis and a reduction of no less than 50%on the surface imaginary part of deuteron GOP is required for describing the data.In all cases,the 6Li breakup effect is significant and provides repulsive correction to the folding model potential.The reduction on the surface imaginary part of GOP of deuteron reveals a strong suppression of the reaction probability of deuteron as a component of 6Li when compared with that of a free deuteron.Further investigation is performed by considering the d breakup process equivalently within the dynamic polarization potential approach,and the results show that d behaves in a manner similar to a tightly bound nucleus in 6Li induced reactions.展开更多
Based on traditional continuous control strategy for Continuously Variable Transmission(CVT)ratio,according to the principles of shift control strategy for stepped automatic transmission,the influences of throttle ope...Based on traditional continuous control strategy for Continuously Variable Transmission(CVT)ratio,according to the principles of shift control strategy for stepped automatic transmission,the influences of throttle opening and external resistance or vehicle speed on CVT ratio control are analyzed on bumpy road.Under the same variation of external resistance condition,the differences between optimal economic control strategy and optimal dynamic control strategy are discussed.Then,the traditional continuous optimal dynamic and economic control lines are divided into multi-step upshift points.Meanwhile,the corresponding downshift points are set to avoid the interference near shift points.After that,the novel discretized ratio control methods for CVT system are proposed.By respectively discretizing throttle opening and vehicle speed,the discretized ratio control strategy for throttle opening,and the integrated discretized ratio control strategy for throttle opening and vehicle speed are further proposed and simulated.Furthermore,the hardware-in-the-loop(HIL)test system is built to further verify the feasibility and accuracy of discretized ratio control strategies.Both simulation and HIL test results show that the sensitivity of throttle opening and vehicle speed to ratio control is reduced dramatically,the fluctuation of ratio is decreased considerably,the transmission efficiency is increased significantly,and the jerk is declined moderately.展开更多
A 32-channel charge-sensitive amplifier(CSA)is designed for fast timing in the delay-line readout of a parallel plate avalanche counter(PPAC)array.It is realized on a PCB with operational amplifiers and other discrete...A 32-channel charge-sensitive amplifier(CSA)is designed for fast timing in the delay-line readout of a parallel plate avalanche counter(PPAC)array.It is realized on a PCB with operational amplifiers and other discrete components.Each channel consists of an integrator,a pole-zero cancellation net,and a linear amplification stage,which can be adapted to accommodate either positive or negative input signals.The RMS equivalent input noise charges are 3.3 fC,the conversion gains are approximately±2 mV∕fC,and the intrinsic time resolution reaches 32 ps.In the prototype PPAC application,the CSA performs as well as the commercial FTA820A amplifier,providing a position resolution as good as 0.17 mm,and exhibiting reliable stability during several hours of continuous data acquisition.展开更多
In this paper,a novel method for investigating the particle-crushing behavior of breeding particles in a fusion blanket is proposed.The fractal theory and Weibull distribution are combined to establish a theoretical m...In this paper,a novel method for investigating the particle-crushing behavior of breeding particles in a fusion blanket is proposed.The fractal theory and Weibull distribution are combined to establish a theoretical model,and its validity was verified using a simple impact test.A crushable discrete element method(DEM)framework is built based on the previously established theoretical model.The tensile strength,which considers the fractal theory,size effect,and Weibull variation,was assigned to each generated particle.The assigned strength is then used for crush detection by comparing it with its maximum tensile stress.Mass conservation is ensured by inserting a series of sub-particles whose total mass was equal to the quality loss.Based on the crushable DEM framework,a numerical simulation of the crushing behavior of a pebble bed with hollow cylindrical geometry under a uniaxial compression test was performed.The results of this investigation showed that the particle withstands the external load by contact and sliding at the beginning of the compression process,and the results confirmed that crushing can be considered an important method of resisting the increasing external load.A relatively regular particle arrangement aids in resisting the load and reduces the occurrence of particle crushing.However,a limit exists to the promotion of resistance.When the strain increases beyond this limit,the distribution of the crushing position tends to be isotropic over the entire pebble bed.The theoretical model and crushable DEM framework provide a new method for exploring the pebble bed in a fusion reactor,considering particle crushing.展开更多
In contrast to cyclic polymers with ring-like backbones,side-chain cyclization is another intriguing structural feature that has not been extensively studied.In this study,a library of orthogonally protected monomers ...In contrast to cyclic polymers with ring-like backbones,side-chain cyclization is another intriguing structural feature that has not been extensively studied.In this study,a library of orthogonally protected monomers featuring monocyclic,dicyclic,or tricyclic pendant motifs was designed and prepared based on malic acid derivatives.Polyesters with precise chemical structures and uniform chain lengths were prepared modularly through iterative growth.Meticulous control over the chemical details allows for a close investigation of the topological effects on the polymer properties.Compared to their linear side chain counterparts,the presence of cyclic pendant groups has a significant impact on chain conformation,leading to a reduction in hydrodynamic volume and an enhancement in the glass transition temperature.These results underscore the potential of tailoring polymer properties through rational engineering of side chain topology.展开更多
The pseudo-two-dimensional(P2D)model plays an important role in exploring physicochemical mechanisms,predicting the state of health,and improving the fast charge capability for Li-ion batteries(LIBs).However,the fast ...The pseudo-two-dimensional(P2D)model plays an important role in exploring physicochemical mechanisms,predicting the state of health,and improving the fast charge capability for Li-ion batteries(LIBs).However,the fast charge leads to the lithium concentration gradient in the solid and electrolyte phases and the non-uniform electrochemical reaction at the solid/electrolyte interface.In order to decouple charge transfer reactions in LIBs under dynamic conditions,understanding the spatio-temporal resolution of the P2D model is urgently required.Till now,the study of this aspect is still insufficient.This work studies the spatio-temporal resolution for dynamic/static electrochemical impedance spectroscopy(DEIS/SEIS)on multiple scales.In detail,DEIS and SEIS with spatio-temporal resolutions are used to decouple charge transfer reactions in LIBs based on the numerical solution of the P2D model in the frequency domain.The calculated results indicate that decoupling solid diffusion requires a high spatial resolution along the r-direction in particles,decoupling electrolyte diffusion and interfacial transfer reaction requires a high spatial resolution along the x-direction,and decoupling charge transfer reactions in LIBs at an extremely low state of charge(SOC)requires an extremely high temporal resolution along the t-direction.Finally,the optimal range of spatio-temporal resolutions for DEIS/SEIS is derived,and the method to decouple charge transfer reactions with spatio-temporal resolutions is developed.展开更多
Seabed mining operations have been found to induce significant movement and deformation in overlying rock strata,posing serious threats to mining safety.The presence of geological faults further complicates these defo...Seabed mining operations have been found to induce significant movement and deformation in overlying rock strata,posing serious threats to mining safety.The presence of geological faults further complicates these deformation patterns.This study utilized geophysical surveys and the continuum-based discrete element method(CDEM)to investigate how fault activity influences rock deformation and failure.The results demonstrate that:1)Acting in mechanically weak zones,faults exerted a pronounced barrier effect on deformation propagation and stress redistribution within the surrounding rock,leading to markedly divergent displacement patterns on either side of the fault plane.Comparative analyses between single-fault and double-fault models revealed an 18%−22%expansion of the damage zone under the latter,together with significantly intensified deformation and failure;2)The double-fault model exhibited a larger maximum cumulative vertical displacement and a spatial shift in the location of peak deformation,thereby posing a heightened threat to mine safety;3)Acting in an orebody substitute,backfill effectively constrained surrounding rock deformation,enhanced its load-bearing capacity,and delayed the overburden subsidence.Nevertheless,backfill only reduced the amplitude of deformation;it could not entirely prevent settlement.These findings provide essential theoretical insights and foundational knowledge for safer submarine mining practices.展开更多
Stony debris flows,characterized by coarse boulders embedded in a sediment-laden matrix,greatly amplify destructive potential by altering flow dynamics and impact forces.Conventional single-phase particle-fluidmixture...Stony debris flows,characterized by coarse boulders embedded in a sediment-laden matrix,greatly amplify destructive potential by altering flow dynamics and impact forces.Conventional single-phase particle-fluidmixture models often struggle to capture the complexities introduced by coarse boulders and multi-phase interactions,while strong-coupling methods can be computationally prohibitive for practical hazard assessments.In this study,we propose a semi-hybrid,fully resolved coupling numerical framework for modeling boulder-laden debris flows.This framework conceptualizes debris flows as a composite system comprising a continuous viscous fluidphase(including finesediments)and a discrete phase of arbitrarily shaped coarse particles.The continuous phase is treated as a generalized nonlinear Coulomb-viscoplastic fluidusing the smoothed particle hydrodynamics(SPH)method,while coarse particles are modeled via the distributed contact discrete element method(DCDEM).These two phases are coupled through an efficienttwo-way resolved scheme,ensuring accurate simulation of flow-boulder interactions within a unifiedtimeframe.We validate the proposed method against two physical experiments:(1)gravity-driven concrete flows and(2)debris flowinteracting with slit-type barriers.Results confirmthe method's robustness in accurately capturing fluid-solid-structureinteractions and deposition processes.Its capabilities are further showcased through the simulation of a stony debris-flowevent inWenchuan County,China,highlighting its promise for real-world engineering applications and validating the effectiveness of the existing cascade dam system in mitigating debrisflowimpact and energy dissipation.展开更多
The strong convergence of an explicit full-discrete scheme is investigated for the stochastic Burgers-Huxley equation driven by additive space-time white noise,which possesses both Burgers-type and cubic nonlinearitie...The strong convergence of an explicit full-discrete scheme is investigated for the stochastic Burgers-Huxley equation driven by additive space-time white noise,which possesses both Burgers-type and cubic nonlinearities.To discretize the continuous problem in space,we utilize a spectral Galerkin method.Subsequently,we introduce a nonlinear-tamed exponential integrator scheme,resulting in a fully discrete scheme.Within the framework of semigroup theory,this study provides precise estimations of the Sobolev regularity,L^(∞) regularity in space,and Hölder continuity in time for the mild solution,as well as for its semi-discrete and full-discrete approximations.Building upon these results,we establish moment boundedness for the numerical solution and obtain strong convergence rates in both spatial and temporal dimensions.A numerical example is presented to validate the theoretical findings.展开更多
It is well known that the inhomogeneous Calderón-Zygmund convolution operators are bounded on the local Hardy spaces.In this paper,we prove that these operators are bounded on the local product Hardy spaces and t...It is well known that the inhomogeneous Calderón-Zygmund convolution operators are bounded on the local Hardy spaces.In this paper,we prove that these operators are bounded on the local product Hardy spaces and the Lipschitz spaces.The key ideas used here are the discrete local Calderón identity and a density argument for the inhomogeneous product Lipschitz spaces in the weak sense.展开更多
基金supported by the National High Technology Research and Development Program of China(863 Program, Grant No.2006AA09Z240)the National Deep-Sea Technology Project of Development and Re-search(Grant No.DYXM-115-04-02-01)
文摘In order to achieve the complex dynamic analysis of the self-propelled seafloor pilot miner moving on the seafloor of extremely cohesive soft soil and further to make it possible to integrate the miner system with some subsystems to form the complete integrated deep ocean mining pilot system and perform dynamic analysis, a new method for the dynamic modeling and analysis of the miner is proposed and developed in this paper, resulting in a simplified 3D single-body vehicle model with three translational and three rotational degrees of freedom, while the track-terrain interaction model is built by partitioning the track-terrain interface into discrete elements with parameterized force dements built on the theory of terramechanics acting on each discrete dement. To evaluate and verify the correctness and effectiveness of this new modeling and analysis method, typical comparative studies with regard to computational efficiency and solution accuracy are carried out between the traditional modeling method of building the tracked vehicle as a multi-body model and the new modeling method. In full consideration of the particMar structure design of the pilot miner, the special characteristics of the seafioor soil and the hydrodynamic force of near-seafloor currnt, the dynamic simulation analysis of the miner is performed and discussed, which can provide useful guidance and reference for the practical miner system in design and operation. This new method can not only realize the rapid dynamic simulation analysis of the miner but also make possible the integration and rapid dynamic analysis of the complete integrated deep ocean mining pilot system in further researches.
基金Supported by the National Natural Science Foundation of China under Grant No. 60772023by the Open Fund of the State Key Laboratory of Software Development Environment under Grant No. BUAA-SKLSDE-09KF-04+2 种基金Beijing University of Aeronautics and Astronautics, by the National Basic Research Program of China (973 Program) under Grant No. 2005CB321901the Specialized Research Fund for the Doctoral Program of Higher Education under Grant Nos. 20060006024 and 200800130006Chinese Ministry of Education, and Scientific Research Common Program of Beijing Municipal Commission of Education under Grant No. KM201010772020
文摘The modified Korteweg-de Vries （mKdV） typed equations can be used to describe certain nonlinear phenomena in fluids, plasmas, and optics. In this paper, the discretized mKdV lattice equation is investigated. With the aid of symbolic computation, the discrete matrix spectral problem for that system is constructed. Darboux transformation for that system is established based on the resulting spectral problem. Explicit solutions are derived via the Darboux transformation. Structures of those solutions are shown graphically, which might be helpful to understand some physical processes in fluids, plasmas, and optics.
基金the National Key Basic Research Project of China under
文摘In this letter, we study discretized mKdV lattice equation by using a new generalized ansatz. As a result,many explicit rational exact solutions, including some new solitary wave solutions, are obtained by symbolic computation code Maple.
基金Project supported by the National Natural Science Foundation and of the Ministry of Construction of China
文摘For nonlinear stability problems of discretized conservative systems with multiple parameter variables and multiple state variables, the activation method is put forward, by which activated potential functions and activated equilibrium equations are derived. The activation method is the improvement and enhancement of Liapunov-Schmidt method in elastic stability theory. It is more generalized and more normalized than conventional perturbation methods. The activated potential functions may be transformed into normalized catastrophe potential functions. The activated equilibrium equations may be treated as bifurcation equations. The researches in this paper will motivate the combination of elastic stability theory with catastrophe theory and bifurcation theory
基金the National Natural ScienceFoundation of China(Grant 11772190),which is gratefully acknowledged.
文摘The rock fragmentation involves the inter-block and the intra-block fracture.A simulation method for rock fragmentation is developed by coupling Voronoi diagram(VD)and discretized virtual internal bond(DVIB).The DVIB is a lattice model that consists of bonds.The VD is used to generate the potential block structure in the DVIB mesh.Each potential block may contain any number of bond cells.To characterize the inter-block fracture,a hyperelastic bond potential is employed for the bond cells that are cut by the VD edges.While to characterize the intra-block fracture,an elastobrittle bond potential is adopted for the bonds in a block.By this method,both the inter-block and intra-block fracture can be well simulated.The simulation results suggest that this method is a simple and efficient approach to rock fragmentation simulation with block smash.
基金the National High Technology Research and Development Program (863) of China(No. 2006AA05Z148)
文摘This paper focuses on the robust stability for time-delay systems of neutral type. A new complete Lyapunov-Krasovskii function (LKF) is developed. Based on this function and discretization, stability conditions in terms of linear matrix inequalities are obtained. A class of time-varying uncertainty of system matrices can be studied by the method.
文摘Discrete software reliability measurement has a proper characteristic for describing a software reliability growth process which depends on a unit of the software fault-detection period, such as the number of test runs, the number of executed test cases. This paper discusses discrete software reliability measurement based on a discretized nonhomogeneous Poisson process (NHPP) model. Especially, we use a bootstrapping method in our discrete software reliability measurement for discussing the statistical inference on parameters and software reliability assessment measures of our model. Finally we show numerical examples of interval estimations based on our bootstrapping method for the several software reliability assessment measures by using actual data.
文摘The complex structure and strong heterogeneity of advanced nuclear reactor systems pose challenges for high-fidelity neutron-shielding calculations. Unstructured meshes exhibit strong geometric adaptability and can overcome the deficiencies of conventionally structured meshes in complex geometry modeling. A multithreaded parallel upwind sweep algorithm for S_(N) transport was proposed to achieve a more accurate geometric description and improve the computational efficiency. The spatial variables were discretized using the standard discontinuous Galerkin finite-element method. The angular flux transmission between neighboring meshes was handled using an upwind scheme. In addition, a combination of a mesh transport sweep and angular iterations was realized using a multithreaded parallel technique. The algorithm was implemented in the 2D/3D S_(N) transport code ThorSNIPE, and numerical evaluations were conducted using three typical benchmark problems:IAEA, Kobayashi-3i, and VENUS-3. These numerical results indicate that the multithreaded parallel upwind sweep algorithm can achieve high computational efficiency. ThorSNIPE, with a multithreaded parallel upwind sweep algorithm, has good reliability, stability, and high efficiency, making it suitable for complex shielding calculations.
文摘In this paper, a discretized SIR model with pulse vaccination and time delay is proposed. We introduce two thresholds R* and R<sub>*</sub>, and further prove that the disease-free periodic solution is globally attractive if R* is less than unit and the disease can invade if R<sub>*</sub> is larger than unit. The numerical simulations not only illustrate the validity of our main results, but also exhibit bifurcation phenomenon. Our result shows that decreasing infection rate can put off the disease outbreak and reduce the number of infected individuals.
基金supported by the National Priorities Research Program through the Qatar National Research Funda member of Qatar Foundation(Grant No.NPRP 4-1162-1-181)+2 种基金the Natural Science Foundation of China(Grant Nos.6140331361374078&61375102)the Natural Science Foundation Project of Chongqing CSTC(Grant No.cstc2014jcyj A40014)
文摘This paper presents an Euler discretized inertial delayed neuron model, and its bifurcation dynamical behaviors are discussed. By using the associated characteristic model, center manifold theorem and the normal form method, it is shown that the model not only undergoes codimension one(flip, Neimark-Sacker) bifurcation, but also undergoes cusp and resonance bifurcation(1:1 and 1:2) of codimension two. Further, it is found that the parity of delay has some effect on bifurcation behaviors. Finally, some numerical simulations are given to support the analytic results and explore complex dynamics, such as periodic orbits near homoclinic orbits, quasiperiodic orbits, and chaotic orbits.
基金Supported by the National Natural Science Foundation of China(U2067205)。
文摘We present a systematic study of 6Li elastic scattering and total reaction cross sections at incident energies around the Coulomb barrier within the continuum discretized coupled-channels(CDCC)framework,where 6Li is treated in anα+d two-body model.Collisions with 27Al,64Zn,138Ba,and 208Pa are analyzed.The microscopic optical potentials(MOP)based on Skyrme nucleon-nucleon interaction forαand d are adopted in CDCC calculations and satisfactory agreement with the experimental data is obtained without any adjustment on MOPs.For comparison,αand d global phenomenological optical potentials(GOP)are also used in CDCC analysis and a reduction of no less than 50%on the surface imaginary part of deuteron GOP is required for describing the data.In all cases,the 6Li breakup effect is significant and provides repulsive correction to the folding model potential.The reduction on the surface imaginary part of GOP of deuteron reveals a strong suppression of the reaction probability of deuteron as a component of 6Li when compared with that of a free deuteron.Further investigation is performed by considering the d breakup process equivalently within the dynamic polarization potential approach,and the results show that d behaves in a manner similar to a tightly bound nucleus in 6Li induced reactions.
基金This work was supported by National Natural Science Foundation of China(Grant No.51305473)Project Funded by China Postdoctoral Science Foundation(Grant No.2014M552317)+1 种基金Postdoctoral Science Funded Project of Chongqing(Grant No.xm2014032)Foundation and Advanced Research Program General Project of Chongqing City,China(Grant No.cstc2014jcyjA60006).Finally,the authors are grateful to the anonymous reviewers for their helpful comments and constructive suggestions.
文摘Based on traditional continuous control strategy for Continuously Variable Transmission(CVT)ratio,according to the principles of shift control strategy for stepped automatic transmission,the influences of throttle opening and external resistance or vehicle speed on CVT ratio control are analyzed on bumpy road.Under the same variation of external resistance condition,the differences between optimal economic control strategy and optimal dynamic control strategy are discussed.Then,the traditional continuous optimal dynamic and economic control lines are divided into multi-step upshift points.Meanwhile,the corresponding downshift points are set to avoid the interference near shift points.After that,the novel discretized ratio control methods for CVT system are proposed.By respectively discretizing throttle opening and vehicle speed,the discretized ratio control strategy for throttle opening,and the integrated discretized ratio control strategy for throttle opening and vehicle speed are further proposed and simulated.Furthermore,the hardware-in-the-loop(HIL)test system is built to further verify the feasibility and accuracy of discretized ratio control strategies.Both simulation and HIL test results show that the sensitivity of throttle opening and vehicle speed to ratio control is reduced dramatically,the fluctuation of ratio is decreased considerably,the transmission efficiency is increased significantly,and the jerk is declined moderately.
基金supported by the National Natural Science Foundation of China(Nos.U2167202,12225504,12005276)the Natural Science Foundation of Shandong Province(No.ZR2024QA172)the Fundamental Research Funds of Shandong University.
文摘A 32-channel charge-sensitive amplifier(CSA)is designed for fast timing in the delay-line readout of a parallel plate avalanche counter(PPAC)array.It is realized on a PCB with operational amplifiers and other discrete components.Each channel consists of an integrator,a pole-zero cancellation net,and a linear amplification stage,which can be adapted to accommodate either positive or negative input signals.The RMS equivalent input noise charges are 3.3 fC,the conversion gains are approximately±2 mV∕fC,and the intrinsic time resolution reaches 32 ps.In the prototype PPAC application,the CSA performs as well as the commercial FTA820A amplifier,providing a position resolution as good as 0.17 mm,and exhibiting reliable stability during several hours of continuous data acquisition.
基金supported by Anhui Provincial Natural Science Foundation(2408085QA030)Natural Science Research Project of Anhui Educational Committee,China(2022AH050825)+3 种基金Medical Special Cultivation Project of Anhui University of Science and Technology(YZ2023H2C008)the Excellent Research and Innovation Team of Anhui Province,China(2022AH010052)the Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology,China(2021yjrc51)Collaborative Innovation Program of Hefei Science Center,CAS,China(2019HSC-CIP006).
文摘In this paper,a novel method for investigating the particle-crushing behavior of breeding particles in a fusion blanket is proposed.The fractal theory and Weibull distribution are combined to establish a theoretical model,and its validity was verified using a simple impact test.A crushable discrete element method(DEM)framework is built based on the previously established theoretical model.The tensile strength,which considers the fractal theory,size effect,and Weibull variation,was assigned to each generated particle.The assigned strength is then used for crush detection by comparing it with its maximum tensile stress.Mass conservation is ensured by inserting a series of sub-particles whose total mass was equal to the quality loss.Based on the crushable DEM framework,a numerical simulation of the crushing behavior of a pebble bed with hollow cylindrical geometry under a uniaxial compression test was performed.The results of this investigation showed that the particle withstands the external load by contact and sliding at the beginning of the compression process,and the results confirmed that crushing can be considered an important method of resisting the increasing external load.A relatively regular particle arrangement aids in resisting the load and reduces the occurrence of particle crushing.However,a limit exists to the promotion of resistance.When the strain increases beyond this limit,the distribution of the crushing position tends to be isotropic over the entire pebble bed.The theoretical model and crushable DEM framework provide a new method for exploring the pebble bed in a fusion reactor,considering particle crushing.
基金financially supported by the National Natural Science Foundation of China(No.22273026)Scientific Research Innovation Capability Support Project for Young Faculty(No.ZYGXQNJSKYCXNLZCXM-I15)+3 种基金Basic and Applied Basic Research Foundation of Guangdong Province(2024A1515012401)GJYC program of Guangzhou(No.2024D03J0002)the China Postdoctoral Science Foundation(No.2024M750938)Postdoctoral Fellowship Program of CPSF(No.GZC20240492)for their financial support。
文摘In contrast to cyclic polymers with ring-like backbones,side-chain cyclization is another intriguing structural feature that has not been extensively studied.In this study,a library of orthogonally protected monomers featuring monocyclic,dicyclic,or tricyclic pendant motifs was designed and prepared based on malic acid derivatives.Polyesters with precise chemical structures and uniform chain lengths were prepared modularly through iterative growth.Meticulous control over the chemical details allows for a close investigation of the topological effects on the polymer properties.Compared to their linear side chain counterparts,the presence of cyclic pendant groups has a significant impact on chain conformation,leading to a reduction in hydrodynamic volume and an enhancement in the glass transition temperature.These results underscore the potential of tailoring polymer properties through rational engineering of side chain topology.
基金supported by the National Natural Science Foundation of China(Nos.22479092 and 22078190)。
文摘The pseudo-two-dimensional(P2D)model plays an important role in exploring physicochemical mechanisms,predicting the state of health,and improving the fast charge capability for Li-ion batteries(LIBs).However,the fast charge leads to the lithium concentration gradient in the solid and electrolyte phases and the non-uniform electrochemical reaction at the solid/electrolyte interface.In order to decouple charge transfer reactions in LIBs under dynamic conditions,understanding the spatio-temporal resolution of the P2D model is urgently required.Till now,the study of this aspect is still insufficient.This work studies the spatio-temporal resolution for dynamic/static electrochemical impedance spectroscopy(DEIS/SEIS)on multiple scales.In detail,DEIS and SEIS with spatio-temporal resolutions are used to decouple charge transfer reactions in LIBs based on the numerical solution of the P2D model in the frequency domain.The calculated results indicate that decoupling solid diffusion requires a high spatial resolution along the r-direction in particles,decoupling electrolyte diffusion and interfacial transfer reaction requires a high spatial resolution along the x-direction,and decoupling charge transfer reactions in LIBs at an extremely low state of charge(SOC)requires an extremely high temporal resolution along the t-direction.Finally,the optimal range of spatio-temporal resolutions for DEIS/SEIS is derived,and the method to decouple charge transfer reactions with spatio-temporal resolutions is developed.
基金Project(42072305)supported by the National Natural Science Foundation of China。
文摘Seabed mining operations have been found to induce significant movement and deformation in overlying rock strata,posing serious threats to mining safety.The presence of geological faults further complicates these deformation patterns.This study utilized geophysical surveys and the continuum-based discrete element method(CDEM)to investigate how fault activity influences rock deformation and failure.The results demonstrate that:1)Acting in mechanically weak zones,faults exerted a pronounced barrier effect on deformation propagation and stress redistribution within the surrounding rock,leading to markedly divergent displacement patterns on either side of the fault plane.Comparative analyses between single-fault and double-fault models revealed an 18%−22%expansion of the damage zone under the latter,together with significantly intensified deformation and failure;2)The double-fault model exhibited a larger maximum cumulative vertical displacement and a spatial shift in the location of peak deformation,thereby posing a heightened threat to mine safety;3)Acting in an orebody substitute,backfill effectively constrained surrounding rock deformation,enhanced its load-bearing capacity,and delayed the overburden subsidence.Nevertheless,backfill only reduced the amplitude of deformation;it could not entirely prevent settlement.These findings provide essential theoretical insights and foundational knowledge for safer submarine mining practices.
基金supported by the Japan Society for the Promotion of Science(JSPS)KAKENHI(Grant Nos.JP23KK0182,JP23K26356,and JP24K00971).
文摘Stony debris flows,characterized by coarse boulders embedded in a sediment-laden matrix,greatly amplify destructive potential by altering flow dynamics and impact forces.Conventional single-phase particle-fluidmixture models often struggle to capture the complexities introduced by coarse boulders and multi-phase interactions,while strong-coupling methods can be computationally prohibitive for practical hazard assessments.In this study,we propose a semi-hybrid,fully resolved coupling numerical framework for modeling boulder-laden debris flows.This framework conceptualizes debris flows as a composite system comprising a continuous viscous fluidphase(including finesediments)and a discrete phase of arbitrarily shaped coarse particles.The continuous phase is treated as a generalized nonlinear Coulomb-viscoplastic fluidusing the smoothed particle hydrodynamics(SPH)method,while coarse particles are modeled via the distributed contact discrete element method(DCDEM).These two phases are coupled through an efficienttwo-way resolved scheme,ensuring accurate simulation of flow-boulder interactions within a unifiedtimeframe.We validate the proposed method against two physical experiments:(1)gravity-driven concrete flows and(2)debris flowinteracting with slit-type barriers.Results confirmthe method's robustness in accurately capturing fluid-solid-structureinteractions and deposition processes.Its capabilities are further showcased through the simulation of a stony debris-flowevent inWenchuan County,China,highlighting its promise for real-world engineering applications and validating the effectiveness of the existing cascade dam system in mitigating debrisflowimpact and energy dissipation.
基金partially supported by the National Natural Science Foundation of China(Grant No.12071073)financial support by the Jiangsu Provincial Scientific Research Center of Applied Mathematics(Grant No.BK20233002).
文摘The strong convergence of an explicit full-discrete scheme is investigated for the stochastic Burgers-Huxley equation driven by additive space-time white noise,which possesses both Burgers-type and cubic nonlinearities.To discretize the continuous problem in space,we utilize a spectral Galerkin method.Subsequently,we introduce a nonlinear-tamed exponential integrator scheme,resulting in a fully discrete scheme.Within the framework of semigroup theory,this study provides precise estimations of the Sobolev regularity,L^(∞) regularity in space,and Hölder continuity in time for the mild solution,as well as for its semi-discrete and full-discrete approximations.Building upon these results,we establish moment boundedness for the numerical solution and obtain strong convergence rates in both spatial and temporal dimensions.A numerical example is presented to validate the theoretical findings.
基金supported by the NSFC(12301115)the Natural Science Foundation of Huzhou(2023YZ11,2024YZ37)the second author was supported by the NSFC(12071437).
文摘It is well known that the inhomogeneous Calderón-Zygmund convolution operators are bounded on the local Hardy spaces.In this paper,we prove that these operators are bounded on the local product Hardy spaces and the Lipschitz spaces.The key ideas used here are the discrete local Calderón identity and a density argument for the inhomogeneous product Lipschitz spaces in the weak sense.
