The use of metal oxides has been extensively documented in the literature and applied in a variety of contexts,including but not limited to energy storage,chemical sensors,and biomedical applications.One of the most s...The use of metal oxides has been extensively documented in the literature and applied in a variety of contexts,including but not limited to energy storage,chemical sensors,and biomedical applications.One of the most significant applications of metal oxides is heterogeneous catalysis,which represents a pivotal technology in industrial production on a global scale.Catalysts serve as the primary enabling agents for chemical reactions,and among the plethora of catalysts,metal oxides including magnesium oxide(MgO),ceria(CeO_(2))and titania(TiO_(2)),have been identified to be particularly effective in catalyzing a variety of reactions[1].Theoretical calculations based on density functional theory(DFT)and a multitude of other quantum chemistry methods have proven invaluable in elucidating the mechanisms of metal-oxide-catalyzed reactions,thereby facilitating the design of high-performance catalysts[2].展开更多
By using the Born-von Kfirmfin theory of lattice dynamics and the modified analytic embedded atom method, we reproduce the experimental results of the phonon dispersion in fcc metal Cu at zero pressure along three hig...By using the Born-von Kfirmfin theory of lattice dynamics and the modified analytic embedded atom method, we reproduce the experimental results of the phonon dispersion in fcc metal Cu at zero pressure along three high symmetry directions and four oft-symmetry directions, and then simulate the phonon dispersion curves of Cu at high pressures of 50, 100, and 150 GPa. The results show that the shapes of dispersion curves at high pressures are very similar to that at zero pressure. All the vibration frequencies of Cu in all vibration branches at high pressures are larger than the results at zero pressure, and increase correspondingly as pressure reaches 50, 100, and 150 GPa sequentially. Moreover, on the basis of phonon dispersion, we calculate the values of specific heat of Cu at different pressures. The prediction of thermodynamic quantities lays a significant foundation for guiding and judging experiments of thermodynamic properties of solids under high pressures.展开更多
The embedded boundary method for solving elliptic and parabolic problems in geometrically complex domains using Cartesian meshes by Johansen and Colella （1998, J. Comput. Phys. 147, 60） has been extended for ellipti...The embedded boundary method for solving elliptic and parabolic problems in geometrically complex domains using Cartesian meshes by Johansen and Colella （1998, J. Comput. Phys. 147, 60） has been extended for elliptic and parabolic problems with interior boundaries or interfaces of discontinuities of material properties or solutions. Second order accuracy is achieved in space and time for both stationary and moving interface problems. The method is conservative for elliptic and parabolic problems with fixed interfaces. Based on this method, a front tracking algorithm for the Stefan problem has been developed. The accuracy of the method is measured through comparison with exact solution to a two-dimensional Stefan problem. The algorithm has been used for the study of melting and solidification problems.展开更多
Prolog is one of the most important candidates to build expert systems and AI-related programs and has potential applications in embedded systems. However, Prolog is not suitable to develop many kinds of components, s...Prolog is one of the most important candidates to build expert systems and AI-related programs and has potential applications in embedded systems. However, Prolog is not suitable to develop many kinds of components, such as data acquisition and task scheduling, which are also crucial. To make the best use of the advantages and bypass the disadvantages, it is attractive to integrate Prolog with programs developed by other languages. In this paper, an IPC-based method is used to integrate backward chaining inference implemented by Prolog into applications or embedded systems. A Prolog design pattern is derived from the method for reuse, whose principle and definition are provided in detail. Additionally, the design pattern is applied to a target system, which is free software, to verify its feasibility. The detailed implementation of the application is given to clarify the design pattern. The design pattern can be further applied to wide range applications and embedded systems and the method described in this paper can also be adopted for other logic programming languages.展开更多
Using current Embedded Discrete Fracture Models(EDFM) to predict the productivity of fractured wells has some drawbacks, such as not supporting corner grid, low precision in the near wellbore zone, and disregarding th...Using current Embedded Discrete Fracture Models(EDFM) to predict the productivity of fractured wells has some drawbacks, such as not supporting corner grid, low precision in the near wellbore zone, and disregarding the heterogeneity of conductivity brought by non-uniform sand concentration. An EDFM is developed based on the corner grid, which enables high efficient calculation of the transmissibility between the embedded fractures and matrix grids, and calculation of the permeability of each polygon in the embedded fractures by the lattice data of the artificial fracture aperture. On this basis, a coupling method of local grid refinement(LGR) and embedded discrete fracture model is designed, which is verified by comparing the calculation results with the Discrete Fracture Network(DFN) method and fitting the actual production data of the first hydraulically fractured well in Iraq. By using this method and orthogonal experimental design, the optimization of the parameters of the first multi-stage fractured horizontal well in the same block is completed. The results show the proposed method has theoretical and practical significance for improving the adaptability of EDFM and the accuracy of productivity prediction of fractured wells, and enables the coupling of fracture modeling and numerical productivity simulation at reservoir scale.展开更多
The holomorphic embedding method(HEM)stands as a mathematical technique renowned for its favorable convergence properties when resolving algebraic systems involving complex variables.The key idea behind the HEM is to ...The holomorphic embedding method(HEM)stands as a mathematical technique renowned for its favorable convergence properties when resolving algebraic systems involving complex variables.The key idea behind the HEM is to convert the task of solving complex algebraic equations into a series expansion involving one or multiple embedded complex variables.This transformation empowers the utilization of complex analysis tools to tackle the original problem effectively.Since the 2010s,the HEM has been applied to steady-state and dynamic problems in power systems and has shown superior convergence and robustness compared to traditional numerical methods.This paper provides a comprehensive review on the diverse applications of the HEM and its variants reported by the literature in the past decade.The paper discusses both the strengths and limitations of these HEMs and provides guidelines for practical applications.It also outlines the challenges and potential directions for future research in this field.展开更多
To understand the atomistic mechanisms of tension failure of Ni-based superalloy,in this study,the classical molecular dynamics(MD)simulations were used to study the uniaxial tension processes of both the Ni/Ni3 Al in...To understand the atomistic mechanisms of tension failure of Ni-based superalloy,in this study,the classical molecular dynamics(MD)simulations were used to study the uniaxial tension processes of both the Ni/Ni3 Al interface systems and the pure Ni and Ni3 Al systems.To examine the effects of interatomic potentials,we adopted embedded atom method(EAM)and reactive force field(ReaxFF)in the MD simulations.The results of EAM simulations showed that the amorphous structures and voids formed near the interface,facilitating further crack propagation within Ni matrix.The EAM potentials also predicted that dislocations were generated and annihilated alternatively,leading to the oscillation of yielding stress during the tension process.The ReaxFF simulations predicted more amorphous formation and larger tensile strength.The atomistic understanding of the defect initiation and propagation during tension process may help to develop the strengthening strategy for controlling the defect evolution under loading.展开更多
Kalman filter is commonly used in data filtering and parameters estimation of nonlinear system,such as projectile's trajectory estimation and control.While there is a drawback that the prior error covariance matri...Kalman filter is commonly used in data filtering and parameters estimation of nonlinear system,such as projectile's trajectory estimation and control.While there is a drawback that the prior error covariance matrix and filter parameters are difficult to be determined,which may result in filtering divergence.As to the problem that the accuracy of state estimation for nonlinear ballistic model strongly depends on its mathematical model,we improve the weighted least squares method(WLSM)with minimum model error principle.Invariant embedding method is adopted to solve the cost function including the model error.With the knowledge of measurement data and measurement error covariance matrix,we use gradient descent algorithm to determine the weighting matrix of model error.The uncertainty and linearization error of model are recursively estimated by the proposed method,thus achieving an online filtering estimation of the observations.Simulation results indicate that the proposed recursive estimation algorithm is insensitive to initial conditions and of good robustness.展开更多
An example of using ultrasonic method to detect the compactness of complicated concrete-filled steel tube in certain high-rise building was discussed in this study.Because of the particularity of the complicated concr...An example of using ultrasonic method to detect the compactness of complicated concrete-filled steel tube in certain high-rise building was discussed in this study.Because of the particularity of the complicated concrete-filled steel tubular column,the plane detection method and embedded sounding pipe method were adopted in the process of effectively detecting the column.According to the results of the plane detection method and embedded sounding pipe method,the cementing status of steel tube and concrete can be concluded,which cannot be judged by the hammering method in the rectangular steel tube-reinforced concrete.展开更多
Molecular dynamics simulation was used to simulate the thermodynamic properties of three binary alloys,Pb-Ag （1：1）,Pb-Ag （4：1）,and Pb-Ag （9：1）.The energy functions,such as excess free energy,cohesive energy,a...Molecular dynamics simulation was used to simulate the thermodynamic properties of three binary alloys,Pb-Ag （1：1）,Pb-Ag （4：1）,and Pb-Ag （9：1）.The energy functions,such as excess free energy,cohesive energy,and formation energy,were calculated.The calculated values agree well with the experimental ones.The atomic interactions were analyzed in macroscopic and microcosmic views and both are consistent well.展开更多
The modified embedded atom method (MEAM) is an empirical extension of the embedded atom method (EAM) that includes angular forces. By fitted to the lattice constants, the cohesive energy, the APE (anti-phase boundary)...The modified embedded atom method (MEAM) is an empirical extension of the embedded atom method (EAM) that includes angular forces. By fitted to the lattice constants, the cohesive energy, the APE (anti-phase boundary) energy, and the vacancy formation energy of TiAl, an accurate MEAM potential is obtained for the TiAl system with L10 structure. The calculation results of the properties of TiAl are in good agreement with experiments and the results of first principle (F.P.) calculations.展开更多
In this paper, thermoelastic problem of onedimensional copper rod under thermal shock is simulated using molecular dynamics method by adopting embedded atom method potential. The rod is on axis x, the left outermost s...In this paper, thermoelastic problem of onedimensional copper rod under thermal shock is simulated using molecular dynamics method by adopting embedded atom method potential. The rod is on axis x, the left outermost surface of which is traction free and the right outermost surface is fixed. Free boundary condition is imposed on the outermost surfaces in direction y and z. The left and right ends of the rod are subjected to hot and cold baths, respectively. Temperature, displacement and stress distributions are obtained along the rod at different moments, which are shown to be limited in the mobile region, indicating that the heat propagation speed is limited rather than infinite. This is consistent with the prediction given by generalized thermoelastic theory. From simulation results we find that the speed of heat conduction is the same as the speed of thermal stress wave. In the present paper, the simulations are conducted using the large-scale atomic/molecular massively parallel simulator and completed visualization software.展开更多
Molecular dynamics(MD) simulations are performed to investigate the effects of stress on generalized stacking fault(GSF) energy of three fcc metals(Cu, Al, and Ni). The simulation model is deformed by uniaxial tension...Molecular dynamics(MD) simulations are performed to investigate the effects of stress on generalized stacking fault(GSF) energy of three fcc metals(Cu, Al, and Ni). The simulation model is deformed by uniaxial tension or compression in each of [111], [11-2], and [1-10] directions, respectively, before shifting the lattice to calculate the GSF curve. Simulation results show that the values of unstable stacking fault energy(γusf), stable stacking fault energy(γsf), and unstable twin fault energy(γutf) of the three elements can change with the preloaded tensile or compressive stress in different directions.The ratio of γsf/γusf, which is related to the energy barrier for full dislocation nucleation, and the ratio of γutf/γusf, which is related to the energy barrier for twinning formation are plotted each as a function of the preloading stress. The results of this study reveal that the stress state can change the energy barrier of defect nucleation in the crystal lattice, and thereby can play an important role in the deformation mechanism of nanocrystalline material.展开更多
Naturally fractured reservoirs make important contributions to global oil and gas reserves and production.The modeling and simulation of naturally fractured reservoirs are different from conventional reservoirs as the...Naturally fractured reservoirs make important contributions to global oil and gas reserves and production.The modeling and simulation of naturally fractured reservoirs are different from conventional reservoirs as the existence of natural fractures.To address the development optimization problem of naturally fractured reservoirs,we propose an optimization workflow by coupling the optimization methods with the embedded discrete fracture model(EDFM).Firstly,the effective and superior performance of the workflow is verified based on the conceptual model.The stochastic simplex approximate gradient(StoSAG)algorithm,the ensemble optimization(EnOpt)algorithm,and the particle swarm optimization(PSO)algorithm are implemented for the production optimization of naturally fractured reservoirs based on the improved versions of the Egg model and the PUNQ-S3 model.The results of the two cases demonstrate the effectiveness of this optimization workflow by finding the optimal well controls which yield the maximum net present value(NPV).Compared to the initial well control guess,the final NPV obtained from the production optimization of fractured reservoirs based on all three optimization algorithms is significantly enhanced.Compared with the optimization results of the PSO algorithm,StoSAG and EnOpt have significant advantages in terms of final NPV and computational efficiency.The results also show that fractures have a significant impact on reservoir production.The economic efficiency of fractured reservoir development can be significantly improved by the optimization workflow.展开更多
In introduction we presented a short historical survey of the discovery of superconductivity (SC) up to the Fe-based materials that are not superconducting in a pure state. For this type of material, the transition to...In introduction we presented a short historical survey of the discovery of superconductivity (SC) up to the Fe-based materials that are not superconducting in a pure state. For this type of material, the transition to SC state occurs in presence of different dopants. Recently in the Fe-based materials at high pressures, the SC was obtained at room critical temperature. In this paper, we present the results of calculations of the isolated cluster representing infinitum crystal with Rh and Pd as dopants. All calculations are performed with the suite of programs Gaussian 16. The obtained results are compared with our previous results obtained for embedded cluster using Gaussian 09. In the case of embedded cluster our methodology of the Embedded Cluster Method at the MP2 electron correlation level was applied. In the NBO population analysis two main features are revealed: the independence of charge density transfer from the spin density transfer and, the presence of orbitals with electron density but without spin density. This is similar to the Anderson’s spinless holon and confirms our conclusions in previous publications that the possible mechanism for superconductivity can be the RVB mechanism proposed by Anderson for high T<sub>c</sub> superconductivity in cuprates.展开更多
It is important to reduce data redundancy of stereo video in practical applications. In this paper,first,a data embedding method for stereo video（DEMSV） is investigated by embedding the encoding data into the refere...It is important to reduce data redundancy of stereo video in practical applications. In this paper,first,a data embedding method for stereo video（DEMSV） is investigated by embedding the encoding data into the reference frame to encode stereo video. It can use only one channel to transfer all the video data and the receiver can choose a monocular video decoder or stereo video decoder adaptively. Then,introducing the joint prediction scheme in the coding process of DEMSV,we propose a novel data embedding method for H.264 stereo video codec with joint prediction scheme（DEMSV-JPS） to achieve high coding efficiency. Experimental results show that the proposed method can obtain high peak signal-to-noise ratio（PSNR） and compression ratio（at least 33 dB for the test sequence） . Comparing the testing methods using JPS and without using JPS,we prove that JPS can further improve the objective and visual quality. DEMSV-JPS shows such advantages and will be suitable to applications in real-time environments of stereo-video transmission.展开更多
This paper studies the coalescence of heteroclusters Au767 and Ag767 by using molecular dynamics with the embedded atom method, where layer atomic energy is employed to describe the potential energy variation of per a...This paper studies the coalescence of heteroclusters Au767 and Ag767 by using molecular dynamics with the embedded atom method, where layer atomic energy is employed to describe the potential energy variation of per atom in different layers along radial direction. The results show that the coalescence is driven by releasing the atomic energy of the coalesced zone. The deformation, which is induced by substitutional and vacancy diffusion during the coalescence, makes the coalesced cluster disorder. If the summation of the thermal energy and the released atomic energy is large enough to keep the disorder state, the clusters form a metastable liquid droplet; otherwise, the clusters coalesce into a solid cluster when the coalesced cluster reaches the equilibrium state, and the coalesced cluster experiences liquid to solid ordering changes during the coalescence of a solid Au767 with a liquid Ag767 and a liquid Au767 with a liquid Ag767. The centre of figure of the cluster system is shifted during the coalescence process, and higher coalescence temperature causes larger shift degree.展开更多
Based on the embedded atom method (EAM) proposed by Daw and Baskes and Johnson's model, this paper constructs a new N-body potential for bcc crystal Mo. The procedure of constructing the new N-body potential can b...Based on the embedded atom method (EAM) proposed by Daw and Baskes and Johnson's model, this paper constructs a new N-body potential for bcc crystal Mo. The procedure of constructing the new N-body potential can be applied to other metals. The dislocation emission from a crack tip has been simulated successfully using molecular dynamics method, the result is in good agreement with the elastic solution.展开更多
The electronic state and potential data of U2 molecules are performed by first principle calculations with B3LYP hybrid exchange-correlation functional, the valence electrons of U atom are treated with the （5s4p3d4f...The electronic state and potential data of U2 molecules are performed by first principle calculations with B3LYP hybrid exchange-correlation functional, the valence electrons of U atom are treated with the （5s4p3d4f）/[3s3p2d2f] contraction basis sets, and the cores are approximated with the relativistic effective core potential. The results show that the ground electronic state is x^9∑g＋. The pair potential data are fitted with a Murrell-Sorbie analytical potential function. The U-U embedded atom method （EAM） interatomic potential is determined based on the generalized gradient approximation calculation within the framework of the density functional theory using Perdew-Burke-Ernzerhof exchange-correlation functional at the spin-polarized level. The physical properties, such as the cohesive energy, the lattice constant, the bulk modulus, the shear modulus, the sc/fec relative energy, the hep/fce rela- tive energy, the shear modulus and the monovacaney formation energy are used to evaluate the EAM potential parameters. The U-U pair potential determined by the first principle calculations is in agreement with that defined by the EAM potential parameters. The EAM calculated formation energy of the monovacancy in the fee structure is also found to be in close agreement with DFT calculation.展开更多
In this paper. we present a class of' embedding methods for nonsmooth equations. Under suitable conditions, we Prove that there exists a homotopy solution curve, which is Unique and continuous. We also prove that ...In this paper. we present a class of' embedding methods for nonsmooth equations. Under suitable conditions, we Prove that there exists a homotopy solution curve, which is Unique and continuous. We also prove that the solution curve is singlcvalue-d with respect to the homotopy parameter. Then we construct all efficient algorithm for this class of equations and prove its convcrgcnce. Filially, we apply the algorithm to the nonlinear complementarity problem. The numerical results show that tile algorithm is satisfacotry.展开更多
基金financial support from the National Key R&D Program of China(2021YFB3500700)the National Natural Science Foundation of China(22473042,22003016,and 92145302).
文摘The use of metal oxides has been extensively documented in the literature and applied in a variety of contexts,including but not limited to energy storage,chemical sensors,and biomedical applications.One of the most significant applications of metal oxides is heterogeneous catalysis,which represents a pivotal technology in industrial production on a global scale.Catalysts serve as the primary enabling agents for chemical reactions,and among the plethora of catalysts,metal oxides including magnesium oxide(MgO),ceria(CeO_(2))and titania(TiO_(2)),have been identified to be particularly effective in catalyzing a variety of reactions[1].Theoretical calculations based on density functional theory(DFT)and a multitude of other quantum chemistry methods have proven invaluable in elucidating the mechanisms of metal-oxide-catalyzed reactions,thereby facilitating the design of high-performance catalysts[2].
基金supported by the National Natural Science Foundation of China (Grant Nos. 61078057 and 11204227)the Scientific Research Program of Education Department of Shaanxi Province, China (Grant No. 12JK0958)
文摘By using the Born-von Kfirmfin theory of lattice dynamics and the modified analytic embedded atom method, we reproduce the experimental results of the phonon dispersion in fcc metal Cu at zero pressure along three high symmetry directions and four oft-symmetry directions, and then simulate the phonon dispersion curves of Cu at high pressures of 50, 100, and 150 GPa. The results show that the shapes of dispersion curves at high pressures are very similar to that at zero pressure. All the vibration frequencies of Cu in all vibration branches at high pressures are larger than the results at zero pressure, and increase correspondingly as pressure reaches 50, 100, and 150 GPa sequentially. Moreover, on the basis of phonon dispersion, we calculate the values of specific heat of Cu at different pressures. The prediction of thermodynamic quantities lays a significant foundation for guiding and judging experiments of thermodynamic properties of solids under high pressures.
基金supported by the U.S.Department of Energy under Contract No.DE-AC02-98CH10886 and by the State of New York
文摘The embedded boundary method for solving elliptic and parabolic problems in geometrically complex domains using Cartesian meshes by Johansen and Colella （1998, J. Comput. Phys. 147, 60） has been extended for elliptic and parabolic problems with interior boundaries or interfaces of discontinuities of material properties or solutions. Second order accuracy is achieved in space and time for both stationary and moving interface problems. The method is conservative for elliptic and parabolic problems with fixed interfaces. Based on this method, a front tracking algorithm for the Stefan problem has been developed. The accuracy of the method is measured through comparison with exact solution to a two-dimensional Stefan problem. The algorithm has been used for the study of melting and solidification problems.
基金supported by the National Natural Science Foundation of China (No.61304111)National Basic Research Program of China (No. 2014CB744904)Fundamental Research Funds for the Central Universities of China (Nos. YWF-14-KKX-001 and YWF-13-JQCJ)
文摘Prolog is one of the most important candidates to build expert systems and AI-related programs and has potential applications in embedded systems. However, Prolog is not suitable to develop many kinds of components, such as data acquisition and task scheduling, which are also crucial. To make the best use of the advantages and bypass the disadvantages, it is attractive to integrate Prolog with programs developed by other languages. In this paper, an IPC-based method is used to integrate backward chaining inference implemented by Prolog into applications or embedded systems. A Prolog design pattern is derived from the method for reuse, whose principle and definition are provided in detail. Additionally, the design pattern is applied to a target system, which is free software, to verify its feasibility. The detailed implementation of the application is given to clarify the design pattern. The design pattern can be further applied to wide range applications and embedded systems and the method described in this paper can also be adopted for other logic programming languages.
基金Supported by the China National Science and Technology Major Project (2017ZX05030)
文摘Using current Embedded Discrete Fracture Models(EDFM) to predict the productivity of fractured wells has some drawbacks, such as not supporting corner grid, low precision in the near wellbore zone, and disregarding the heterogeneity of conductivity brought by non-uniform sand concentration. An EDFM is developed based on the corner grid, which enables high efficient calculation of the transmissibility between the embedded fractures and matrix grids, and calculation of the permeability of each polygon in the embedded fractures by the lattice data of the artificial fracture aperture. On this basis, a coupling method of local grid refinement(LGR) and embedded discrete fracture model is designed, which is verified by comparing the calculation results with the Discrete Fracture Network(DFN) method and fitting the actual production data of the first hydraulically fractured well in Iraq. By using this method and orthogonal experimental design, the optimization of the parameters of the first multi-stage fractured horizontal well in the same block is completed. The results show the proposed method has theoretical and practical significance for improving the adaptability of EDFM and the accuracy of productivity prediction of fractured wells, and enables the coupling of fracture modeling and numerical productivity simulation at reservoir scale.
文摘The holomorphic embedding method(HEM)stands as a mathematical technique renowned for its favorable convergence properties when resolving algebraic systems involving complex variables.The key idea behind the HEM is to convert the task of solving complex algebraic equations into a series expansion involving one or multiple embedded complex variables.This transformation empowers the utilization of complex analysis tools to tackle the original problem effectively.Since the 2010s,the HEM has been applied to steady-state and dynamic problems in power systems and has shown superior convergence and robustness compared to traditional numerical methods.This paper provides a comprehensive review on the diverse applications of the HEM and its variants reported by the literature in the past decade.The paper discusses both the strengths and limitations of these HEMs and provides guidelines for practical applications.It also outlines the challenges and potential directions for future research in this field.
基金financially supported by the National Key Research and Development Program of China(Grant Nos.2017YFB0701502 and 2017YFB0702901)the National Nature Science Foundation of China(Grant No.91641128)
文摘To understand the atomistic mechanisms of tension failure of Ni-based superalloy,in this study,the classical molecular dynamics(MD)simulations were used to study the uniaxial tension processes of both the Ni/Ni3 Al interface systems and the pure Ni and Ni3 Al systems.To examine the effects of interatomic potentials,we adopted embedded atom method(EAM)and reactive force field(ReaxFF)in the MD simulations.The results of EAM simulations showed that the amorphous structures and voids formed near the interface,facilitating further crack propagation within Ni matrix.The EAM potentials also predicted that dislocations were generated and annihilated alternatively,leading to the oscillation of yielding stress during the tension process.The ReaxFF simulations predicted more amorphous formation and larger tensile strength.The atomistic understanding of the defect initiation and propagation during tension process may help to develop the strengthening strategy for controlling the defect evolution under loading.
基金This work is supported by Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX18_0467)Jiangsu Province,China.During the revision of this paper,the author is supported by China Scholarship Council(No.201906840021)China to continue some research related to data processing.
文摘Kalman filter is commonly used in data filtering and parameters estimation of nonlinear system,such as projectile's trajectory estimation and control.While there is a drawback that the prior error covariance matrix and filter parameters are difficult to be determined,which may result in filtering divergence.As to the problem that the accuracy of state estimation for nonlinear ballistic model strongly depends on its mathematical model,we improve the weighted least squares method(WLSM)with minimum model error principle.Invariant embedding method is adopted to solve the cost function including the model error.With the knowledge of measurement data and measurement error covariance matrix,we use gradient descent algorithm to determine the weighting matrix of model error.The uncertainty and linearization error of model are recursively estimated by the proposed method,thus achieving an online filtering estimation of the observations.Simulation results indicate that the proposed recursive estimation algorithm is insensitive to initial conditions and of good robustness.
文摘An example of using ultrasonic method to detect the compactness of complicated concrete-filled steel tube in certain high-rise building was discussed in this study.Because of the particularity of the complicated concrete-filled steel tubular column,the plane detection method and embedded sounding pipe method were adopted in the process of effectively detecting the column.According to the results of the plane detection method and embedded sounding pipe method,the cementing status of steel tube and concrete can be concluded,which cannot be judged by the hammering method in the rectangular steel tube-reinforced concrete.
基金supported by the National Natural Science Foundation of China-Yunnan United Foundation (No. U0837604)
文摘Molecular dynamics simulation was used to simulate the thermodynamic properties of three binary alloys,Pb-Ag （1：1）,Pb-Ag （4：1）,and Pb-Ag （9：1）.The energy functions,such as excess free energy,cohesive energy,and formation energy,were calculated.The calculated values agree well with the experimental ones.The atomic interactions were analyzed in macroscopic and microcosmic views and both are consistent well.
基金the National Natural Science Foundation of China.
文摘The modified embedded atom method (MEAM) is an empirical extension of the embedded atom method (EAM) that includes angular forces. By fitted to the lattice constants, the cohesive energy, the APE (anti-phase boundary) energy, and the vacancy formation energy of TiAl, an accurate MEAM potential is obtained for the TiAl system with L10 structure. The calculation results of the properties of TiAl are in good agreement with experiments and the results of first principle (F.P.) calculations.
基金supported by the National Natural Science Foundation of China (10872158)
文摘In this paper, thermoelastic problem of onedimensional copper rod under thermal shock is simulated using molecular dynamics method by adopting embedded atom method potential. The rod is on axis x, the left outermost surface of which is traction free and the right outermost surface is fixed. Free boundary condition is imposed on the outermost surfaces in direction y and z. The left and right ends of the rod are subjected to hot and cold baths, respectively. Temperature, displacement and stress distributions are obtained along the rod at different moments, which are shown to be limited in the mobile region, indicating that the heat propagation speed is limited rather than infinite. This is consistent with the prediction given by generalized thermoelastic theory. From simulation results we find that the speed of heat conduction is the same as the speed of thermal stress wave. In the present paper, the simulations are conducted using the large-scale atomic/molecular massively parallel simulator and completed visualization software.
基金supported by Australia Research Council Discovery Projects(Grant No.DP130103973)financially supported by the China Scholarship Council(CSC)
文摘Molecular dynamics(MD) simulations are performed to investigate the effects of stress on generalized stacking fault(GSF) energy of three fcc metals(Cu, Al, and Ni). The simulation model is deformed by uniaxial tension or compression in each of [111], [11-2], and [1-10] directions, respectively, before shifting the lattice to calculate the GSF curve. Simulation results show that the values of unstable stacking fault energy(γusf), stable stacking fault energy(γsf), and unstable twin fault energy(γutf) of the three elements can change with the preloaded tensile or compressive stress in different directions.The ratio of γsf/γusf, which is related to the energy barrier for full dislocation nucleation, and the ratio of γutf/γusf, which is related to the energy barrier for twinning formation are plotted each as a function of the preloading stress. The results of this study reveal that the stress state can change the energy barrier of defect nucleation in the crystal lattice, and thereby can play an important role in the deformation mechanism of nanocrystalline material.
基金This study was supported by the National Natural Science Foundation of China(51904323,52174052).
文摘Naturally fractured reservoirs make important contributions to global oil and gas reserves and production.The modeling and simulation of naturally fractured reservoirs are different from conventional reservoirs as the existence of natural fractures.To address the development optimization problem of naturally fractured reservoirs,we propose an optimization workflow by coupling the optimization methods with the embedded discrete fracture model(EDFM).Firstly,the effective and superior performance of the workflow is verified based on the conceptual model.The stochastic simplex approximate gradient(StoSAG)algorithm,the ensemble optimization(EnOpt)algorithm,and the particle swarm optimization(PSO)algorithm are implemented for the production optimization of naturally fractured reservoirs based on the improved versions of the Egg model and the PUNQ-S3 model.The results of the two cases demonstrate the effectiveness of this optimization workflow by finding the optimal well controls which yield the maximum net present value(NPV).Compared to the initial well control guess,the final NPV obtained from the production optimization of fractured reservoirs based on all three optimization algorithms is significantly enhanced.Compared with the optimization results of the PSO algorithm,StoSAG and EnOpt have significant advantages in terms of final NPV and computational efficiency.The results also show that fractures have a significant impact on reservoir production.The economic efficiency of fractured reservoir development can be significantly improved by the optimization workflow.
文摘In introduction we presented a short historical survey of the discovery of superconductivity (SC) up to the Fe-based materials that are not superconducting in a pure state. For this type of material, the transition to SC state occurs in presence of different dopants. Recently in the Fe-based materials at high pressures, the SC was obtained at room critical temperature. In this paper, we present the results of calculations of the isolated cluster representing infinitum crystal with Rh and Pd as dopants. All calculations are performed with the suite of programs Gaussian 16. The obtained results are compared with our previous results obtained for embedded cluster using Gaussian 09. In the case of embedded cluster our methodology of the Embedded Cluster Method at the MP2 electron correlation level was applied. In the NBO population analysis two main features are revealed: the independence of charge density transfer from the spin density transfer and, the presence of orbitals with electron density but without spin density. This is similar to the Anderson’s spinless holon and confirms our conclusions in previous publications that the possible mechanism for superconductivity can be the RVB mechanism proposed by Anderson for high T<sub>c</sub> superconductivity in cuprates.
基金Supported by the National Natural Science foundation of China (60832003)
文摘It is important to reduce data redundancy of stereo video in practical applications. In this paper,first,a data embedding method for stereo video（DEMSV） is investigated by embedding the encoding data into the reference frame to encode stereo video. It can use only one channel to transfer all the video data and the receiver can choose a monocular video decoder or stereo video decoder adaptively. Then,introducing the joint prediction scheme in the coding process of DEMSV,we propose a novel data embedding method for H.264 stereo video codec with joint prediction scheme（DEMSV-JPS） to achieve high coding efficiency. Experimental results show that the proposed method can obtain high peak signal-to-noise ratio（PSNR） and compression ratio（at least 33 dB for the test sequence） . Comparing the testing methods using JPS and without using JPS,we prove that JPS can further improve the objective and visual quality. DEMSV-JPS shows such advantages and will be suitable to applications in real-time environments of stereo-video transmission.
基金supported by the National Natural Science Foundation of China (Grant No 50374027)the program for New Century Excellent Talents in University of China (Grant No NCET-06-0289)the 111 project of China (Grant No B07015)
文摘This paper studies the coalescence of heteroclusters Au767 and Ag767 by using molecular dynamics with the embedded atom method, where layer atomic energy is employed to describe the potential energy variation of per atom in different layers along radial direction. The results show that the coalescence is driven by releasing the atomic energy of the coalesced zone. The deformation, which is induced by substitutional and vacancy diffusion during the coalescence, makes the coalesced cluster disorder. If the summation of the thermal energy and the released atomic energy is large enough to keep the disorder state, the clusters form a metastable liquid droplet; otherwise, the clusters coalesce into a solid cluster when the coalesced cluster reaches the equilibrium state, and the coalesced cluster experiences liquid to solid ordering changes during the coalescence of a solid Au767 with a liquid Ag767 and a liquid Au767 with a liquid Ag767. The centre of figure of the cluster system is shifted during the coalescence process, and higher coalescence temperature causes larger shift degree.
基金The project supported by the National Natural Science Foundation of China
文摘Based on the embedded atom method (EAM) proposed by Daw and Baskes and Johnson's model, this paper constructs a new N-body potential for bcc crystal Mo. The procedure of constructing the new N-body potential can be applied to other metals. The dislocation emission from a crack tip has been simulated successfully using molecular dynamics method, the result is in good agreement with the elastic solution.
文摘The electronic state and potential data of U2 molecules are performed by first principle calculations with B3LYP hybrid exchange-correlation functional, the valence electrons of U atom are treated with the （5s4p3d4f）/[3s3p2d2f] contraction basis sets, and the cores are approximated with the relativistic effective core potential. The results show that the ground electronic state is x^9∑g＋. The pair potential data are fitted with a Murrell-Sorbie analytical potential function. The U-U embedded atom method （EAM） interatomic potential is determined based on the generalized gradient approximation calculation within the framework of the density functional theory using Perdew-Burke-Ernzerhof exchange-correlation functional at the spin-polarized level. The physical properties, such as the cohesive energy, the lattice constant, the bulk modulus, the shear modulus, the sc/fec relative energy, the hep/fce rela- tive energy, the shear modulus and the monovacaney formation energy are used to evaluate the EAM potential parameters. The U-U pair potential determined by the first principle calculations is in agreement with that defined by the EAM potential parameters. The EAM calculated formation energy of the monovacancy in the fee structure is also found to be in close agreement with DFT calculation.
文摘In this paper. we present a class of' embedding methods for nonsmooth equations. Under suitable conditions, we Prove that there exists a homotopy solution curve, which is Unique and continuous. We also prove that the solution curve is singlcvalue-d with respect to the homotopy parameter. Then we construct all efficient algorithm for this class of equations and prove its convcrgcnce. Filially, we apply the algorithm to the nonlinear complementarity problem. The numerical results show that tile algorithm is satisfacotry.
