Molecular dynamics simulations were carried out to study the configuration energy and radial distribution functions of mmonium dihydrogen phosphate solution at different temperatures. The dihydrogen phosphate ion was ...Molecular dynamics simulations were carried out to study the configuration energy and radial distribution functions of mmonium dihydrogen phosphate solution at different temperatures. The dihydrogen phosphate ion was treated as a seven-site model and the ammonium ion was regarded as a five-site model, while a simple-point-charge model for water molecule. An unusually local particle number density fluctuation was observed in the system at saturation temperature. It can be found that the potential energy increases slowly with the temperature from 373 K to 404 K, which indicates that the ammonium dihydrogen phosphate has partly decomposed. The radial distribution function between the hydrogen atom of ammonium cation and the oxygen atom of dihydrogen phosphate ion at three different temperatures shows obvious difference, which indicates that the average H-bond number changes obviously with the temperature. The temperature has an influence on the combination between hydrogen atoms and phosphorus atoms of dihydrogen phosphate ion and there are much more growth units at saturated solutions.展开更多
A kind of amphiphilic functional monomer was selected to modify polyacrylamide （PAM） or partially hydrolyzed polyacrylamide （HPAM）. The relative properties of the modified polyacrylamide （HM-PAM） and modified pa...A kind of amphiphilic functional monomer was selected to modify polyacrylamide （PAM） or partially hydrolyzed polyacrylamide （HPAM）. The relative properties of the modified polyacrylamide （HM-PAM） and modified partially hydrolyzed polyacrylamide （HM-HPAM） such as radius of gyration （Rg）, hydrodynamic radius （RH）, and radial distribution functions （RDFs） have been studied to find the intrinsic relation between the microstructure of the polymer chain and the intrinsic viscosities with changing the amotmt of modified monomers from 1% to 4%. The simulation results show that, compared to HPAM, HM-HPAM has a better performance in increasing viscosity when the percentage of modified monomers is 2% and has a stronger salt tolerance when the modified monomers is 4%. Furthermore, a complex hydrogen bonding network was revealed with the analysis of radial distribution functions （RDFs） and the pair correlation function was used to investigate the diffusivity of Na^＋ and carbon atoms in the COO^- group.展开更多
The dynamics, stability and control problem of a kind of infinite dimensional system are studied in the functional space with the method of modern Mathematics. First, the dynamical control model of the distributed par...The dynamics, stability and control problem of a kind of infinite dimensional system are studied in the functional space with the method of modern Mathematics. First, the dynamical control model of the distributed parameter system with multi-body flexible and multi-topological structure was established which has damping, gyroscopic parts and constrained damping. Secondly, the necessary and sufficient condition of controllability and observability, the stability theory and asymptotic property of the system were obtained. These results expand the theory of the field about the dynamics and control of the system with multi-body flexible structure, and have important engineering significance.展开更多
The nonlinear activation functions in the deep CNN(Convolutional Neural Network)based on fluid dynamics are presented.We propose two types of activation functions by applying the so-called parametric softsign to the n...The nonlinear activation functions in the deep CNN(Convolutional Neural Network)based on fluid dynamics are presented.We propose two types of activation functions by applying the so-called parametric softsign to the negative region.We use significantly the well-known TensorFlow as the deep learning framework.The CNN architecture consists of three convolutional layers with the max-pooling and one fullyconnected softmax layer.The CNN approaches are applied to three benchmark datasets,namely,MNIST,CIFAR-10,and CIFAR-100.Numerical results demonstrate the workability and the validity of the present approach through comparison with other numerical performances.展开更多
The adiabatic control is a powerful technique for many practical applications in quantum state engineering,light-driven chemical reactions and geometrical quantum computations.This paper reveals a speed limit of nonad...The adiabatic control is a powerful technique for many practical applications in quantum state engineering,light-driven chemical reactions and geometrical quantum computations.This paper reveals a speed limit of nonadiabatic transition in a general time-dependent parametric quantum system that leads to an upper bound function which lays down an optimal criteria for the adiabatic controls.The upper bound function of transition rate between instantaneous eigenstates of a time-dependent system is determined by the power fluctuations of the system relative to the minimum gap between the instantaneous levels.In a parametric Hilbert space,the driving power corresponds to the quantum work done by the parametric force multiplying the parametric velocity along the parametric driving path.The general two-state time-dependent models are investigated as examples to calculate the bound functions in some general driving schemes with one and two driving parameters.The calculations show that the upper bound function provides a tighter real-time estimation of nonadiabatic transition and is closely dependent on the driving frequencies and the energy gap of the system.The deviations of the real phase from Berry phase on different closed paths are induced by the nonadiabatic transitions and can be efficiently controlled by the upper bound functions.When the upper bound is adiabatically controlled,the Berry phases of the electronic spin exhibit nonlinear step-like behaviors and it is closely related to topological structures of the complicated parametric paths on Bloch sphere.展开更多
In recent years,there has been a surge of interest in air-ground collaborative robotics technologies.Our research group designs a novel combination-separation air-ground robot(CSAGR),which exhibits rapid automatic com...In recent years,there has been a surge of interest in air-ground collaborative robotics technologies.Our research group designs a novel combination-separation air-ground robot(CSAGR),which exhibits rapid automatic combination and separation capabilities.During the combination process,contact effects between robots,as well as between robots and the environment,are unavoidable.Therefore,it is essential to conduct detailed and accurate modeling and analysis of the collision impact intensity and transmission pathways within the robotic system to ensure the successful execution of the combination procedure.This paper addresses the intricate surface geometries and multi-point contact challenges present in the contact regions of dual robots by making appropriate modifications to the traditional continuous contact force model and applying equivalent processing techniques.The validity of the developed model is confirmed through comparisons with results obtained from finite element analysis(FEA),which demonstrates its high fidelity.Additionally,the impact of this model on control performance is analyzed within the flight control system,thereby further ensuring the successful completion of the combination process.This research represents a pioneering application and validation of continuous contact theory in the dynamics of collisions within dual robot systems.展开更多
Static disorder plays a crucial role in the electronic dynamics and spec-troscopy of complex molecular sys-tems.Traditionally,obtaining ob-servables averaged over static disor-der requires thousands of realiza-tions v...Static disorder plays a crucial role in the electronic dynamics and spec-troscopy of complex molecular sys-tems.Traditionally,obtaining ob-servables averaged over static disor-der requires thousands of realiza-tions via direct sampling of the dis-order distribution,leading to high computational costs.In this work,we extend the auxiliary degree-of-freedom based matrix product state(MPS)method to handle system-bath correlated thermal equilibrium initial states,which can capture static disorder effects using a one-shot quantum dynamical simulation.We validate the effectiveness of the extended method by computing the dipole-dipole time correlation function of the Holstein model relevant to the emission spectrum of molecular aggregates.Our results show that the one-shot method is very accu-rate with only a moderate increase in MPS bond dimension,thereby significantly reducing computational cost.Moreover,it enables the generation of a much larger number of samples than the conventional direct sampling method at negligible additional cost,thus reducing sta-tistical errors.This method provides a broadly useful tool for calculating equilibrium time cor-relation functions in system-bath coupled models with static disorder.展开更多
For non-stationary complex dynamic systems,a standardized algorithm is developed to compute time correlation functions,addressing the limitations of traditional methods reliant on the stationary assumption.The propose...For non-stationary complex dynamic systems,a standardized algorithm is developed to compute time correlation functions,addressing the limitations of traditional methods reliant on the stationary assumption.The proposed algorithm integrates two-point and multi-point time correlation functions into a unified framework.Further,it is verified by a practical application in complex financial systems,demonstrating its potential in various complex dynamic systems.展开更多
The Dynamical Density Functional Theory(DDFT)algorithm,derived by associating classical Density Functional Theory(DFT)with the fundamental Smoluchowski dynamical equation,describes the evolution of inhomo-geneous flui...The Dynamical Density Functional Theory(DDFT)algorithm,derived by associating classical Density Functional Theory(DFT)with the fundamental Smoluchowski dynamical equation,describes the evolution of inhomo-geneous fluid density distributions over time.It plays a significant role in studying the evolution of density distributions over time in inhomogeneous systems.The Sunway Bluelight II supercomputer,as a new generation of China’s developed supercomputer,possesses powerful computational capabilities.Porting and optimizing industrial software on this platform holds significant importance.For the optimization of the DDFT algorithm,based on the Sunway Bluelight II supercomputer and the unique hardware architecture of the SW39000 processor,this work proposes three acceleration strategies to enhance computational efficiency and performance,including direct parallel optimization,local-memory constrained optimization for CPEs,and multi-core groups collaboration and communication optimization.This method combines the characteristics of the program’s algorithm with the unique hardware architecture of the Sunway Bluelight II supercomputer,optimizing the storage and transmission structures to achieve a closer integration of software and hardware.For the first time,this paper presents Sunway-Dynamical Density Functional Theory(SW-DDFT).Experimental results show that SW-DDFT achieves a speedup of 6.67 times within a single-core group compared to the original DDFT implementation,with six core groups(a total of 384 CPEs),the maximum speedup can reach 28.64 times,and parallel efficiency can reach 71%,demonstrating excellent acceleration performance.展开更多
Structural Reliability-Based Topology Optimization(RBTO),as an efficient design methodology,serves as a crucial means to ensure the development ofmodern engineering structures towards high performance,long service lif...Structural Reliability-Based Topology Optimization(RBTO),as an efficient design methodology,serves as a crucial means to ensure the development ofmodern engineering structures towards high performance,long service life,and high reliability.However,in practical design processes,topology optimization must not only account for the static performance of structures but also consider the impacts of various responses and uncertainties under complex dynamic conditions,which traditional methods often struggle accommodate.Therefore,this study proposes an RBTO framework based on a Kriging-assisted level set function and a novel Dynamic Hybrid Particle Swarm Optimization(DHPSO)algorithm.By leveraging the Kriging model as a surrogate,the high cost associated with repeatedly running finite element analysis processes is reduced,addressing the issue of minimizing structural compliance.Meanwhile,the DHPSO algorithm enables a better balance between the population’s developmental and exploratory capabilities,significantly accelerating convergence speed and enhancing global convergence performance.Finally,the proposed method is validated through three different structural examples,demonstrating its superior performance.Observed that the computational that,compared to the traditional Solid Isotropic Material with Penalization(SIMP)method,the proposed approach reduces the upper bound of structural compliance by approximately 30%.Additionally,the optimized results exhibit clear material interfaces without grayscale elements,and the stress concentration factor is reduced by approximately 42%.Consequently,the computational results fromdifferent examples verify the effectiveness and superiority of this study across various fields,achieving the goal of providing more precise optimization results within a shorter timeframe.展开更多
The microstructure and intermolecular interaction of toluene(TOL), methyl ethyl ketone(MEK), lube oil, TOL-MEK solvents, and TOL-MEK-oil solutions were studied by molecular simulation. Some simulation results agree we...The microstructure and intermolecular interaction of toluene(TOL), methyl ethyl ketone(MEK), lube oil, TOL-MEK solvents, and TOL-MEK-oil solutions were studied by molecular simulation. Some simulation results agree well with the experiment, which suggests that the simulation method we adopted is a powerful tool to obtain microscopic property of the systems. The density functional theory(DFT) calculation results suggest that the interaction group of toluene and MEK is the methyl group of theirs. And the interaction between toluene and MEK is attractive. The contribution of van der Waals interaction to the change of total energy of the TOL-MEK system is major, and the second is electrostatic interaction. Molecular dynamics(MD) simulation analyzes the solubility parameter(SP), mean square displacement(MSD), radius of gyration(RG), and radial distribution function(RDF) of solvents and solutions. The results are that the solubility parameter of the blend solvents decreases with temperature, and increases with the proportion of methyl ethyl ketone in principle, and that of lube oil also trends to decrease with temperature. The MSD results give one reason of why the transmission rate of MEK is greater in membrane separation process of recovery toluene and MEK and the permeation flux increases with MEK:TOL. The RG analysis predicts that the permeability of the oil molecule is likely to rise with temperature during dewaxing solvent recovery process by membrane. The analysis of RDFs shows that the intermolecular interaction of C···C, O···O and C···O makes a major contribution to the total interaction energy.展开更多
Internal resonance in nonlinear vibration of functionally graded （FG） circular cylin- drical shells in thermal environment is studied using the Hamiltonian dynamics formulation. The material properties are considere...Internal resonance in nonlinear vibration of functionally graded （FG） circular cylin- drical shells in thermal environment is studied using the Hamiltonian dynamics formulation. The material properties are considered to be temperature-dependent. Based on the Karman-Donnell＇s nonlinear shell theory, the kinetic and potential energy of FG cylindrical thin shells are formu- lated. The primary target is to investigate the two-mode internal resonance, which is triggered by geometric and material parameters of shells. Following a secular perturbation procedure, the underlying dynamic characteristics of the two-mode interactions in both exact and near resonance cases are fully discussed. It is revealed that the system will undergo a bifurcation in near resonance case, which induces the dynamic response at high energy level being distinct from the motion at low energy level. The effects of temperature and volume fractions of composition on the exact resonance condition and bifurcation characteristics of FG cylindrical shells are also investigated.展开更多
By using first-principles simulations based on time-dependent density functional theory, the chemical reaction of an HCl molecule encapsulated in C60 induced by femtosecond laser pulses is observed. The H atom starts ...By using first-principles simulations based on time-dependent density functional theory, the chemical reaction of an HCl molecule encapsulated in C60 induced by femtosecond laser pulses is observed. The H atom starts to leave the Cl atom and is reflected by the C60 wall. The coherent nuclear dynamic behaviors of bond breakage and recombination of the HCl molecule occurring in both polarized parallel and perpendicular to the H-Cl bond axis are investigated. The radial oscillation is also found in the two polarization directions of the laser pulse. The relaxation time of the H-Cl bond lengths in transverse polarization is slow in comparison with that in longitudinal polarization. Those results are important for studying the dynamics of the chemical bond at an atomic level.展开更多
Isomorphism of the two-state system is heuristic in understanding the dynamical or statistical behavior of the simplest yet most quantum system that has no classical counterpart.We use the constraint phase space devel...Isomorphism of the two-state system is heuristic in understanding the dynamical or statistical behavior of the simplest yet most quantum system that has no classical counterpart.We use the constraint phase space developed in J.Chem.Phys.145,204105(2016);151,024105(2019);J.Phys.Chem.Lett.12,2496(2021),non-covariant phase space functions,time-dependent weight functions,and time-dependent normalization factors to construct a novel class of phase space representations of the exact population dynamics of the two-state quantum system.The equations of motion of the trajectory on constraint phase space are isomorphic to the time-dependent Schrödinger equation.The contribution of each trajectory to the integral expression for the population dynamics is always positive semi-definite.We also prove that the triangle window function approach,albeit proposed as a heuristic empirical model in J.Chem.Phys.145,144108(2016),is related to a special case of the novel class and leads to an isomorphic representation of the exact population dynamics of the two-state quantum system.展开更多
In this paper,a semi-discrete model based on peridynamics(PD)for engineered cementitious composites(ECCs)is applied to simulate the fracture behavior of functionally graded ECC(FGECC)beams.This is a new application of...In this paper,a semi-discrete model based on peridynamics(PD)for engineered cementitious composites(ECCs)is applied to simulate the fracture behavior of functionally graded ECC(FGECC)beams.This is a new application of PD in ECC.Prior to simulating the crack behavior,the convergence of the PD model for ECC is discussed and the appropriate horizon size 5 and nonlocal ratio m are obtained,i.e.,S=1.6 mm and m=4.In addition,when the bond strain exceeds the elastic limit,a damage variable is introduced into the model,and the model is validated using a simple numerical algorithm.Finally,the dynamic fracture behavior of a two-dimensional FGECC beam under four-point bending is investigated,and the effect of the initial crack location on the fracture behavior is analyzed.Simulation results show that the initial crack location can affect the crack propagation pattern,thereby enabling one to understand the dynamic fracture behavior of ECC structures and guide the engineering practice.展开更多
The realization of protein functional movement is usually accompanied by specific conformational changes,and there exist some key residues that mediate and control the functional motions of proteins in the allosteric ...The realization of protein functional movement is usually accompanied by specific conformational changes,and there exist some key residues that mediate and control the functional motions of proteins in the allosteric process.In the present work,the perturbation-response scanning method developed by our group was combined with the molecular dynamics(MD)simulation to identify the key residues controlling the functional movement of proteins.In our method,a physical quantity that is directly related to protein specific function was introduced,and then based on the MD simulation trajectories,the perturbation-response scanning method was used to identify the key residues for functional motions,in which the residues that highly correlated with the fluctuation of the function-related quantity were identified as the key residues controlling the specific functional motions of the protein.Two protein systems,i.e.,the heat shock protein 70 and glutamine binding protein,were selected as case studies to validate the effectiveness of our method.Our calculated results are in good agreement with the experimental results.The location of the key residues in the two proteins are similar,indicating the similar mechanisms behind the performance of their biological functions.展开更多
The coupled nonlocal nonlinear Schrödinger equations with variable coefficients are researched using the nonstandard Hirota bilinear method.The two-soliton and double-hump one-soliton solutions for the equations ...The coupled nonlocal nonlinear Schrödinger equations with variable coefficients are researched using the nonstandard Hirota bilinear method.The two-soliton and double-hump one-soliton solutions for the equations are first obtained.By assigning different functions to the variable coefficients,we obtain V-shaped,Y-shaped,wave-type,exponential solitons,and so on.Next,we reveal the influence of the real and imaginary parts of the wave numbers on the double-hump structure based on the soliton solutions.Finally,by setting different wave numbers,we can change the distance and transmission direction of the solitons to analyze their dynamic behavior during collisions.This study establishes a theoretical framework for controlling the dynamics of optical fiber in nonlocal nonlinear systems.展开更多
The layered Li2MnO3 is investigated by using the first-principles calculations within the GGA and GGA-t-U scheme, respectively. Within the GGA4-U approach, the calculated intercalation voltage （ranges from 4,5 V to 4...The layered Li2MnO3 is investigated by using the first-principles calculations within the GGA and GGA-t-U scheme, respectively. Within the GGA4-U approach, the calculated intercalation voltage （ranges from 4,5 V to 4.9 V） is found to be in good agreement with experiments. From the analysis of electronic structure, the pure phase Li2MnO3 is insulating, which is indicative of poor electronic-conduction properties. However, further studies of lithium ion diffusion in bulk Li2MnO3 show that unlike the two-dimensional diffusion pathways in rock salt structure layered cathode materials, lithium can diffuse in a three-dimensional pathway in Li2MnO3, with moderate lithium migration energy barrier ranges from 0.57 to 0.63 e V.展开更多
The simulation of a control system for the longitudinal axis of the rotary or fixed-wing unmanned aerial vehicles(UAVs)is demonstrated in this study.The control unit includes design considerations of two controllers t...The simulation of a control system for the longitudinal axis of the rotary or fixed-wing unmanned aerial vehicles(UAVs)is demonstrated in this study.The control unit includes design considerations of two controllers to provide robust stability,tracking of the proposed linear dynamics,an adequate set of proportional-integral-derivative(PID)controller gains,and a minimal cost function.The PID control and linear quadratic regulator(LQR)with or without full-state-observer were evaluated.An optimal control system is assumed to provide fast rise and settling time,minimize overshoot,and eliminate the steady-state error.The effectiveness of this approach was verified by a linear model of the UAV aircraft in the semi-dynamic simulation platform of Matlab/Simulink,in which the open-loop system was assessed in terms of flight robustness and reference tracking.The experimental results show that the proposed controllers effectively improve the configuration of the control system of the plant,maintain the sustainability of the dynamic flight model stability,and diminish the flight controller errors.The LQR provides robust stability,but it is not optimal in the transient phase of particular plant output.The PID control system can adjust the controller’s gains for optimal hovering(or stable slow flight)and is especially useful for the tracking system.Finally,comparing aircraft stability using PID and LQR controllers shows that the latter has less overshoot and a shorter settling time;in addition,all proposed controllers can be practically deployed as one UAV’s system,which can be handled as an exemplary model of the UAV flight management system.展开更多
文摘Molecular dynamics simulations were carried out to study the configuration energy and radial distribution functions of mmonium dihydrogen phosphate solution at different temperatures. The dihydrogen phosphate ion was treated as a seven-site model and the ammonium ion was regarded as a five-site model, while a simple-point-charge model for water molecule. An unusually local particle number density fluctuation was observed in the system at saturation temperature. It can be found that the potential energy increases slowly with the temperature from 373 K to 404 K, which indicates that the ammonium dihydrogen phosphate has partly decomposed. The radial distribution function between the hydrogen atom of ammonium cation and the oxygen atom of dihydrogen phosphate ion at three different temperatures shows obvious difference, which indicates that the average H-bond number changes obviously with the temperature. The temperature has an influence on the combination between hydrogen atoms and phosphorus atoms of dihydrogen phosphate ion and there are much more growth units at saturated solutions.
基金financially supported by the National Natural Science Foundation of China(No.20904035)
文摘A kind of amphiphilic functional monomer was selected to modify polyacrylamide （PAM） or partially hydrolyzed polyacrylamide （HPAM）. The relative properties of the modified polyacrylamide （HM-PAM） and modified partially hydrolyzed polyacrylamide （HM-HPAM） such as radius of gyration （Rg）, hydrodynamic radius （RH）, and radial distribution functions （RDFs） have been studied to find the intrinsic relation between the microstructure of the polymer chain and the intrinsic viscosities with changing the amotmt of modified monomers from 1% to 4%. The simulation results show that, compared to HPAM, HM-HPAM has a better performance in increasing viscosity when the percentage of modified monomers is 2% and has a stronger salt tolerance when the modified monomers is 4%. Furthermore, a complex hydrogen bonding network was revealed with the analysis of radial distribution functions （RDFs） and the pair correlation function was used to investigate the diffusivity of Na^＋ and carbon atoms in the COO^- group.
文摘The dynamics, stability and control problem of a kind of infinite dimensional system are studied in the functional space with the method of modern Mathematics. First, the dynamical control model of the distributed parameter system with multi-body flexible and multi-topological structure was established which has damping, gyroscopic parts and constrained damping. Secondly, the necessary and sufficient condition of controllability and observability, the stability theory and asymptotic property of the system were obtained. These results expand the theory of the field about the dynamics and control of the system with multi-body flexible structure, and have important engineering significance.
文摘The nonlinear activation functions in the deep CNN(Convolutional Neural Network)based on fluid dynamics are presented.We propose two types of activation functions by applying the so-called parametric softsign to the negative region.We use significantly the well-known TensorFlow as the deep learning framework.The CNN architecture consists of three convolutional layers with the max-pooling and one fullyconnected softmax layer.The CNN approaches are applied to three benchmark datasets,namely,MNIST,CIFAR-10,and CIFAR-100.Numerical results demonstrate the workability and the validity of the present approach through comparison with other numerical performances.
基金Project supported by the National Natural Science Foundation of China(Emergency Project,Grant Nos.11447025 and 11847308)
文摘The adiabatic control is a powerful technique for many practical applications in quantum state engineering,light-driven chemical reactions and geometrical quantum computations.This paper reveals a speed limit of nonadiabatic transition in a general time-dependent parametric quantum system that leads to an upper bound function which lays down an optimal criteria for the adiabatic controls.The upper bound function of transition rate between instantaneous eigenstates of a time-dependent system is determined by the power fluctuations of the system relative to the minimum gap between the instantaneous levels.In a parametric Hilbert space,the driving power corresponds to the quantum work done by the parametric force multiplying the parametric velocity along the parametric driving path.The general two-state time-dependent models are investigated as examples to calculate the bound functions in some general driving schemes with one and two driving parameters.The calculations show that the upper bound function provides a tighter real-time estimation of nonadiabatic transition and is closely dependent on the driving frequencies and the energy gap of the system.The deviations of the real phase from Berry phase on different closed paths are induced by the nonadiabatic transitions and can be efficiently controlled by the upper bound functions.When the upper bound is adiabatically controlled,the Berry phases of the electronic spin exhibit nonlinear step-like behaviors and it is closely related to topological structures of the complicated parametric paths on Bloch sphere.
基金Supported by National Natural Science Foundation of China(Grant Nos.T2121003 and 91748201).
文摘In recent years,there has been a surge of interest in air-ground collaborative robotics technologies.Our research group designs a novel combination-separation air-ground robot(CSAGR),which exhibits rapid automatic combination and separation capabilities.During the combination process,contact effects between robots,as well as between robots and the environment,are unavoidable.Therefore,it is essential to conduct detailed and accurate modeling and analysis of the collision impact intensity and transmission pathways within the robotic system to ensure the successful execution of the combination procedure.This paper addresses the intricate surface geometries and multi-point contact challenges present in the contact regions of dual robots by making appropriate modifications to the traditional continuous contact force model and applying equivalent processing techniques.The validity of the developed model is confirmed through comparisons with results obtained from finite element analysis(FEA),which demonstrates its high fidelity.Additionally,the impact of this model on control performance is analyzed within the flight control system,thereby further ensuring the successful completion of the combination process.This research represents a pioneering application and validation of continuous contact theory in the dynamics of collisions within dual robot systems.
基金supported by the National Natural Science Foundation of China(No.22273005 and No.22422301)the Innovation Program for Quantum Science and Technology(No.2023ZD0300200)+1 种基金the National Security Academic Foundation(No.U2330201)the Fundamental Research Funds for the Central Universities.
文摘Static disorder plays a crucial role in the electronic dynamics and spec-troscopy of complex molecular sys-tems.Traditionally,obtaining ob-servables averaged over static disor-der requires thousands of realiza-tions via direct sampling of the dis-order distribution,leading to high computational costs.In this work,we extend the auxiliary degree-of-freedom based matrix product state(MPS)method to handle system-bath correlated thermal equilibrium initial states,which can capture static disorder effects using a one-shot quantum dynamical simulation.We validate the effectiveness of the extended method by computing the dipole-dipole time correlation function of the Holstein model relevant to the emission spectrum of molecular aggregates.Our results show that the one-shot method is very accu-rate with only a moderate increase in MPS bond dimension,thereby significantly reducing computational cost.Moreover,it enables the generation of a much larger number of samples than the conventional direct sampling method at negligible additional cost,thus reducing sta-tistical errors.This method provides a broadly useful tool for calculating equilibrium time cor-relation functions in system-bath coupled models with static disorder.
基金Project supported by the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(Grant No.GZC20231050)the National Natural Science Foundation of China(Grant Nos.12175193 and 11905183)the 13th Five-year plan for Education Science Funding of Guangdong Province(Grant No.2021GXJK349)。
文摘For non-stationary complex dynamic systems,a standardized algorithm is developed to compute time correlation functions,addressing the limitations of traditional methods reliant on the stationary assumption.The proposed algorithm integrates two-point and multi-point time correlation functions into a unified framework.Further,it is verified by a practical application in complex financial systems,demonstrating its potential in various complex dynamic systems.
基金supported by National Key Research and Development Program of China under Grant 2024YFE0210800National Natural Science Foundation of China under Grant 62495062Beijing Natural Science Foundation under Grant L242017.
文摘The Dynamical Density Functional Theory(DDFT)algorithm,derived by associating classical Density Functional Theory(DFT)with the fundamental Smoluchowski dynamical equation,describes the evolution of inhomo-geneous fluid density distributions over time.It plays a significant role in studying the evolution of density distributions over time in inhomogeneous systems.The Sunway Bluelight II supercomputer,as a new generation of China’s developed supercomputer,possesses powerful computational capabilities.Porting and optimizing industrial software on this platform holds significant importance.For the optimization of the DDFT algorithm,based on the Sunway Bluelight II supercomputer and the unique hardware architecture of the SW39000 processor,this work proposes three acceleration strategies to enhance computational efficiency and performance,including direct parallel optimization,local-memory constrained optimization for CPEs,and multi-core groups collaboration and communication optimization.This method combines the characteristics of the program’s algorithm with the unique hardware architecture of the Sunway Bluelight II supercomputer,optimizing the storage and transmission structures to achieve a closer integration of software and hardware.For the first time,this paper presents Sunway-Dynamical Density Functional Theory(SW-DDFT).Experimental results show that SW-DDFT achieves a speedup of 6.67 times within a single-core group compared to the original DDFT implementation,with six core groups(a total of 384 CPEs),the maximum speedup can reach 28.64 times,and parallel efficiency can reach 71%,demonstrating excellent acceleration performance.
基金fundings supported by Sichuan Science and Technology Program(2025YFHZ0065).
文摘Structural Reliability-Based Topology Optimization(RBTO),as an efficient design methodology,serves as a crucial means to ensure the development ofmodern engineering structures towards high performance,long service life,and high reliability.However,in practical design processes,topology optimization must not only account for the static performance of structures but also consider the impacts of various responses and uncertainties under complex dynamic conditions,which traditional methods often struggle accommodate.Therefore,this study proposes an RBTO framework based on a Kriging-assisted level set function and a novel Dynamic Hybrid Particle Swarm Optimization(DHPSO)algorithm.By leveraging the Kriging model as a surrogate,the high cost associated with repeatedly running finite element analysis processes is reduced,addressing the issue of minimizing structural compliance.Meanwhile,the DHPSO algorithm enables a better balance between the population’s developmental and exploratory capabilities,significantly accelerating convergence speed and enhancing global convergence performance.Finally,the proposed method is validated through three different structural examples,demonstrating its superior performance.Observed that the computational that,compared to the traditional Solid Isotropic Material with Penalization(SIMP)method,the proposed approach reduces the upper bound of structural compliance by approximately 30%.Additionally,the optimized results exhibit clear material interfaces without grayscale elements,and the stress concentration factor is reduced by approximately 42%.Consequently,the computational results fromdifferent examples verify the effectiveness and superiority of this study across various fields,achieving the goal of providing more precise optimization results within a shorter timeframe.
基金supported by Beijing Key Laboratory of Energy Environmental Catalysis Beijing University of Chemical Technology Beijing of ChinaYanshan Branch of Beijing Research Institute of Chemical Industry,Sinopec
文摘The microstructure and intermolecular interaction of toluene(TOL), methyl ethyl ketone(MEK), lube oil, TOL-MEK solvents, and TOL-MEK-oil solutions were studied by molecular simulation. Some simulation results agree well with the experiment, which suggests that the simulation method we adopted is a powerful tool to obtain microscopic property of the systems. The density functional theory(DFT) calculation results suggest that the interaction group of toluene and MEK is the methyl group of theirs. And the interaction between toluene and MEK is attractive. The contribution of van der Waals interaction to the change of total energy of the TOL-MEK system is major, and the second is electrostatic interaction. Molecular dynamics(MD) simulation analyzes the solubility parameter(SP), mean square displacement(MSD), radius of gyration(RG), and radial distribution function(RDF) of solvents and solutions. The results are that the solubility parameter of the blend solvents decreases with temperature, and increases with the proportion of methyl ethyl ketone in principle, and that of lube oil also trends to decrease with temperature. The MSD results give one reason of why the transmission rate of MEK is greater in membrane separation process of recovery toluene and MEK and the permeation flux increases with MEK:TOL. The RG analysis predicts that the permeability of the oil molecule is likely to rise with temperature during dewaxing solvent recovery process by membrane. The analysis of RDFs shows that the intermolecular interaction of C···C, O···O and C···O makes a major contribution to the total interaction energy.
基金Project supported by the National Natural Science Foundation of China(Nos.11072204 and 11372257)
文摘Internal resonance in nonlinear vibration of functionally graded （FG） circular cylin- drical shells in thermal environment is studied using the Hamiltonian dynamics formulation. The material properties are considered to be temperature-dependent. Based on the Karman-Donnell＇s nonlinear shell theory, the kinetic and potential energy of FG cylindrical thin shells are formu- lated. The primary target is to investigate the two-mode internal resonance, which is triggered by geometric and material parameters of shells. Following a secular perturbation procedure, the underlying dynamic characteristics of the two-mode interactions in both exact and near resonance cases are fully discussed. It is revealed that the system will undergo a bifurcation in near resonance case, which induces the dynamic response at high energy level being distinct from the motion at low energy level. The effects of temperature and volume fractions of composition on the exact resonance condition and bifurcation characteristics of FG cylindrical shells are also investigated.
基金Project supported by the National Natural Science Foundation of China （Grant Nos. 11074176 and 10976019） and the Doctoral Program of Higher Education of China （Grant No. 20100181110080）.
文摘By using first-principles simulations based on time-dependent density functional theory, the chemical reaction of an HCl molecule encapsulated in C60 induced by femtosecond laser pulses is observed. The H atom starts to leave the Cl atom and is reflected by the C60 wall. The coherent nuclear dynamic behaviors of bond breakage and recombination of the HCl molecule occurring in both polarized parallel and perpendicular to the H-Cl bond axis are investigated. The radial oscillation is also found in the two polarization directions of the laser pulse. The relaxation time of the H-Cl bond lengths in transverse polarization is slow in comparison with that in longitudinal polarization. Those results are important for studying the dynamics of the chemical bond at an atomic level.
文摘Isomorphism of the two-state system is heuristic in understanding the dynamical or statistical behavior of the simplest yet most quantum system that has no classical counterpart.We use the constraint phase space developed in J.Chem.Phys.145,204105(2016);151,024105(2019);J.Phys.Chem.Lett.12,2496(2021),non-covariant phase space functions,time-dependent weight functions,and time-dependent normalization factors to construct a novel class of phase space representations of the exact population dynamics of the two-state quantum system.The equations of motion of the trajectory on constraint phase space are isomorphic to the time-dependent Schrödinger equation.The contribution of each trajectory to the integral expression for the population dynamics is always positive semi-definite.We also prove that the triangle window function approach,albeit proposed as a heuristic empirical model in J.Chem.Phys.145,144108(2016),is related to a special case of the novel class and leads to an isomorphic representation of the exact population dynamics of the two-state quantum system.
基金the Natural Science Foundation of China(Nos.11872339,11472248)the Natural Science Foundation of Henan Province(No.182300410221).
文摘In this paper,a semi-discrete model based on peridynamics(PD)for engineered cementitious composites(ECCs)is applied to simulate the fracture behavior of functionally graded ECC(FGECC)beams.This is a new application of PD in ECC.Prior to simulating the crack behavior,the convergence of the PD model for ECC is discussed and the appropriate horizon size 5 and nonlocal ratio m are obtained,i.e.,S=1.6 mm and m=4.In addition,when the bond strain exceeds the elastic limit,a damage variable is introduced into the model,and the model is validated using a simple numerical algorithm.Finally,the dynamic fracture behavior of a two-dimensional FGECC beam under four-point bending is investigated,and the effect of the initial crack location on the fracture behavior is analyzed.Simulation results show that the initial crack location can affect the crack propagation pattern,thereby enabling one to understand the dynamic fracture behavior of ECC structures and guide the engineering practice.
文摘The realization of protein functional movement is usually accompanied by specific conformational changes,and there exist some key residues that mediate and control the functional motions of proteins in the allosteric process.In the present work,the perturbation-response scanning method developed by our group was combined with the molecular dynamics(MD)simulation to identify the key residues controlling the functional movement of proteins.In our method,a physical quantity that is directly related to protein specific function was introduced,and then based on the MD simulation trajectories,the perturbation-response scanning method was used to identify the key residues for functional motions,in which the residues that highly correlated with the fluctuation of the function-related quantity were identified as the key residues controlling the specific functional motions of the protein.Two protein systems,i.e.,the heat shock protein 70 and glutamine binding protein,were selected as case studies to validate the effectiveness of our method.Our calculated results are in good agreement with the experimental results.The location of the key residues in the two proteins are similar,indicating the similar mechanisms behind the performance of their biological functions.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1604200)the National Natural Science Foundation of China(Grant No.12261131495)Institute of Systems Science,Beijing Wuzi University(Grant No.BWUISS21).
文摘The coupled nonlocal nonlinear Schrödinger equations with variable coefficients are researched using the nonstandard Hirota bilinear method.The two-soliton and double-hump one-soliton solutions for the equations are first obtained.By assigning different functions to the variable coefficients,we obtain V-shaped,Y-shaped,wave-type,exponential solitons,and so on.Next,we reveal the influence of the real and imaginary parts of the wave numbers on the double-hump structure based on the soliton solutions.Finally,by setting different wave numbers,we can change the distance and transmission direction of the solitons to analyze their dynamic behavior during collisions.This study establishes a theoretical framework for controlling the dynamics of optical fiber in nonlocal nonlinear systems.
基金Supported by the National Natural Science Foundation of China under Grant No 21363016the Natural Science Foundation of Jiangxi Province under Grant No 20142BAB216030the PhD Early Development Program of Nanchang Hangkong University under Grant No EA201502007
文摘The layered Li2MnO3 is investigated by using the first-principles calculations within the GGA and GGA-t-U scheme, respectively. Within the GGA4-U approach, the calculated intercalation voltage （ranges from 4,5 V to 4.9 V） is found to be in good agreement with experiments. From the analysis of electronic structure, the pure phase Li2MnO3 is insulating, which is indicative of poor electronic-conduction properties. However, further studies of lithium ion diffusion in bulk Li2MnO3 show that unlike the two-dimensional diffusion pathways in rock salt structure layered cathode materials, lithium can diffuse in a three-dimensional pathway in Li2MnO3, with moderate lithium migration energy barrier ranges from 0.57 to 0.63 e V.
文摘The simulation of a control system for the longitudinal axis of the rotary or fixed-wing unmanned aerial vehicles(UAVs)is demonstrated in this study.The control unit includes design considerations of two controllers to provide robust stability,tracking of the proposed linear dynamics,an adequate set of proportional-integral-derivative(PID)controller gains,and a minimal cost function.The PID control and linear quadratic regulator(LQR)with or without full-state-observer were evaluated.An optimal control system is assumed to provide fast rise and settling time,minimize overshoot,and eliminate the steady-state error.The effectiveness of this approach was verified by a linear model of the UAV aircraft in the semi-dynamic simulation platform of Matlab/Simulink,in which the open-loop system was assessed in terms of flight robustness and reference tracking.The experimental results show that the proposed controllers effectively improve the configuration of the control system of the plant,maintain the sustainability of the dynamic flight model stability,and diminish the flight controller errors.The LQR provides robust stability,but it is not optimal in the transient phase of particular plant output.The PID control system can adjust the controller’s gains for optimal hovering(or stable slow flight)and is especially useful for the tracking system.Finally,comparing aircraft stability using PID and LQR controllers shows that the latter has less overshoot and a shorter settling time;in addition,all proposed controllers can be practically deployed as one UAV’s system,which can be handled as an exemplary model of the UAV flight management system.
