Based on non-Darcian flow law described by exponent and threshold gradient within a double-layered soil, the classic theory of one-dimensional consolidation of double-layered soil was modified to consider the change o...Based on non-Darcian flow law described by exponent and threshold gradient within a double-layered soil, the classic theory of one-dimensional consolidation of double-layered soil was modified to consider the change of vertical total stress with depth and time together. Because of the complexity of governing equations, the numerical solutions were obtained in detail by finite difference method. Then, the numerical solutions were compared with the analytical solutions in condition that non-Darcian flow law was degenerated to Dary's law, and the comparison results show that numerical solutions are reliable. Finally, consolidation behavior of double-layered soil with different parameters was analyzed, and the results show that the consolidation rate of double-layered soil decreases with increasing the value of exponent and threshold of non-Darcian flow, and the exponent and threshold gradient of the first soil layer greatly influence the consolidation rate of double-layered soil. The larger the ratio of the equivalent water head of external load to the total thickness of double-layered soil, the larger the rate of the consolidation, and the similitude relationship in classical consolidation theory of double-layered soil is not satisfied. The other consolidation behavior of double-layered soil with non-Darcian flow is the same as that with Darcy's law.展开更多
The time-dependent electro-viscoelastic performance of a circular dielectric elastomer(DE) membrane actuator containing an inclusion is investigated in the context of the nonlinear theory for viscoelastic dielectrics....The time-dependent electro-viscoelastic performance of a circular dielectric elastomer(DE) membrane actuator containing an inclusion is investigated in the context of the nonlinear theory for viscoelastic dielectrics. The membrane, a key part of the actuator, is centrally attached to a rigid inclusion of the radius a, and then connected to a fixed rigid ring of the radius b. When subject to a pressure and a voltage, the membrane inflates into an out-of-plane shape and undergoes an inhomogeneous large deformation. The governing equations for the large deformation are derived by means of non-equilibrium thermodynamics, and viscoelasticity of the membrane is characterized by a rheological spring-dashpot model. In the simulation, effects of the pressure, the voltage, and design parameters on the electromechanical viscoelastic behaviors of the membrane are investigated. Evolutions of the considered variables and profiles of the deformed membrane are obtained numerically and illustrated graphically. The results show that electromechanical loadings and design parameters significantly influence the electro-viscoelastic behaviors of the membrane. The design parameters can be tailored to improve the performance of the membrane. The approach may provide guidelines in designing and optimizing such DE devices.展开更多
Traditional route planners commonly focus on finding the shortest path between two points in terms of travel distance or time over road networks.However,in real cases,especially in the era of smart cities where many k...Traditional route planners commonly focus on finding the shortest path between two points in terms of travel distance or time over road networks.However,in real cases,especially in the era of smart cities where many kinds of transportation-related data become easily available,recent years have witnessed an increasing demand of route planners that need to optimize for multiple criteria,e.g.,finding the route with the highest accumulated scenic score along(utility)while not exceeding the given travel time budget(cost).Such problem can be viewed as a variant of arc orienteering problem(AOP),which is well-known as an NP-hard problem.In this paper,targeting a more realistic AOP,we allow both scenic score(utility)and travel time(cost)values on each arc of the road network are time-dependent(2TD-AOP),and propose a memetic algorithm to solve it.To be more specific,within the given travel time budget,in the phase of initiation,for each population,we iteratively add suitable arcs with high scenic score and build a path from the origin to the destination via a complicate procedure consisting of search region narrowing,chromosome encoding and decoding.In the phase of the local search,each path is improved via chromosome selection,local-improvement-based mutation and crossover operations.Finally,we evaluate the proposed memetic algorithm in both synthetic and real-life datasets extensively,and the experimental results demonstrate that it outperforms the baselines.展开更多
In this paper,we present a discretization of the time-dependent Schrodinger equation based on a Magnus-Lanczos time integrator and high-order Gauss-Lobatto finite elements in space.A truncated Galerkin orthogonality i...In this paper,we present a discretization of the time-dependent Schrodinger equation based on a Magnus-Lanczos time integrator and high-order Gauss-Lobatto finite elements in space.A truncated Galerkin orthogonality is used to obtain dualitybased a posteriori error estimates that address the temporal and the spatial error separately.Based on this theory,a space-time adaptive solver for the Schrodinger equation is devised.An efficient matrix-free implementation of the differential operator,suited for spectral elements,is used to enable computations for realistic configurations.We demonstrate the performance of the algorithm for the example of matter-field interaction.展开更多
A novel method based on time-dependent stochastic orthogonal bases for stochastic response surface approximation is proposed to overcome the problem of significant errors in the utilization of the generalized polynomi...A novel method based on time-dependent stochastic orthogonal bases for stochastic response surface approximation is proposed to overcome the problem of significant errors in the utilization of the generalized polynomial chaos(GPC) method that approximates the stochastic response by orthogonal polynomials. The accuracy and effectiveness of the method are illustrated by different numerical examples including both linear and nonlinear problems. The results indicate that the proposed method modifies the stochastic bases adaptively, and has a better approximation for the probability density function in contrast to the GPC method.展开更多
The emission of scission neutrons from fissioning nuclei is of high practical interest.To study this process we have used the sudden approximation and also a more realistic approach that takes into account the scissio...The emission of scission neutrons from fissioning nuclei is of high practical interest.To study this process we have used the sudden approximation and also a more realistic approach that takes into account the scission dynamics.Numerically,this implies the solution of the bi-dimensional Schr¨odinger equation,both stationary and time-dependent.To describe axially symmetric extremely deformed nuclear shapes,we have used the Cassini parametrization.The Hamiltonian is discretized by using finite difference approximations of the derivatives.The main computational challenges are the solution of algebraic eigenvalue problems and of linear systems with large sparse matrices.We have employed appropriate procedures(Arnoldi and bi-conjugate gradients).The numerical solutions have been used to evaluate physical quantities,like the number of emitted neutrons per scission event,the primary fragments’excitation energy and the distribution of the emission points.展开更多
In this article,a theoretical analysis on flow in a curvilinear horizontal coaxial cylinder with permeable walls has been proposed.Specifically,the transient impact of an oscillating pressure gradient has been taken i...In this article,a theoretical analysis on flow in a curvilinear horizontal coaxial cylinder with permeable walls has been proposed.Specifically,the transient impact of an oscillating pressure gradient has been taken into account.The non-linear time-dependent partial differential equation accountable for the flow has been transformed using the classical Laplace transform technique.Exact solution of the momentum equation has been obtained in Laplace domain.Due to the intricacy of the Laplace domain solutions,a numerical inversing technique which is established upon the Riemann-sum approximation(RSA)has been utilized to transform the Laplace domain solutions to time domain.Findings reveal that the outcome of suction on the porous walls and boosting the frequency of oscillation renders skin frictions on both walls of the cylinder less effective.The instability of the Dean vortices in the annular gap can be suppressed by amplifying the frequency of oscillating pressure gradient while time is maintained.展开更多
Based on the Morlet complex wavelet transformation,the authors put forward a kind of new method for distinguishing periods of seismic activity and quietude and a new physical thought on the time-dependent wavelet accu...Based on the Morlet complex wavelet transformation,the authors put forward a kind of new method for distinguishing periods of seismic activity and quietude and a new physical thought on the time-dependent wavelet accumulation energy spectrum with periods, the time-frequency distribution of wavelet vibration period spectrum and period-specific wavelet vibration spectrum. By applying the above methods to a time series which is composed of earthquake accumulation energy per year for the world, the Chinese continent and North China, respectively, we obtained some new information about the rhythm of shallow earthquake activity. Considering the historic earthquakes and the rhythm characteristics of current strong earthquake activity, the earthquake tendency in the next years is discussed.展开更多
The A-band resonance Raman spectra of thiourea were obtained in water and acetonitrile solution. B3LYP/6-311＋＋G（3df,3pd） and RCIS/6-311＋＋G（3df,3pd） calculations were done to elucidate the ultraviolet electroni...The A-band resonance Raman spectra of thiourea were obtained in water and acetonitrile solution. B3LYP/6-311＋＋G（3df,3pd） and RCIS/6-311＋＋G（3df,3pd） calculations were done to elucidate the ultraviolet electronic transitions, the distorted geometry structure and the saddle point of thiourea in 21A excited state, respectively. The resonance Raman spectra were assigned. The absorption spectrum and resonance Raman intensities were modeled using Heller＇s time-dependent wavepacket approach to resonance Raman scattering. The results indicate that largest change in the displacement takes place with the C--S stretch mode u6 （｜△｜=0.95） and noticeable changes appear in the H5N3H6＋H8N4H7 wag v5 （｜△｜=0.19）, NCN symmetric stretch^-C--S stretch＋N3H6＋H8N4 wag v4 （｜△｜=0.18）, while the moderate intensities of 2-15 and 4-15 are mostly due to the large excited state frequency changes of v15, but not due to its significant change in the normal mode displacement. The mechanism of the appearance of even overtones of the S-CN2 out of plane deformation is explored. The results indicate that a Franck-Condon region saddle point is the driving force for the quadric phonon mechanism within the standard A-term of resonance Raman scattering, which leads to the pyramidalization of the carbon center and the geometry distortion of thiourea molecule in 21A excited state.展开更多
In this work,vortex convection is simulated using a dynamic mesh adaptation procedure.In each adaptation period,the mesh is refined in the regions where the phenomena evolve and is coarsened in the regions where the p...In this work,vortex convection is simulated using a dynamic mesh adaptation procedure.In each adaptation period,the mesh is refined in the regions where the phenomena evolve and is coarsened in the regions where the phenomena deviate since the last adaptation.A simple indicator of mesh adaptation that accounts for the solution progression is defined.The generation of dynamic adaptive meshes is based on multilevel refinement/coarsening.The efficiency and accuracy of the present procedure are validated by simulating vortex convection in a uniform flow.Two unsteady compressible turbulent flows involving blade-vortex interactions are investigated to demonstrate further the applicability of the procedure.Computed results agree well with the published experimental data or numerical results.展开更多
基金Projects(50878191,51109092)supported by the National Natural Science Foundation of China
文摘Based on non-Darcian flow law described by exponent and threshold gradient within a double-layered soil, the classic theory of one-dimensional consolidation of double-layered soil was modified to consider the change of vertical total stress with depth and time together. Because of the complexity of governing equations, the numerical solutions were obtained in detail by finite difference method. Then, the numerical solutions were compared with the analytical solutions in condition that non-Darcian flow law was degenerated to Dary's law, and the comparison results show that numerical solutions are reliable. Finally, consolidation behavior of double-layered soil with different parameters was analyzed, and the results show that the consolidation rate of double-layered soil decreases with increasing the value of exponent and threshold of non-Darcian flow, and the exponent and threshold gradient of the first soil layer greatly influence the consolidation rate of double-layered soil. The larger the ratio of the equivalent water head of external load to the total thickness of double-layered soil, the larger the rate of the consolidation, and the similitude relationship in classical consolidation theory of double-layered soil is not satisfied. The other consolidation behavior of double-layered soil with non-Darcian flow is the same as that with Darcy's law.
基金Project supported by the National Natural Science Foundation of China(No.11372123)
文摘The time-dependent electro-viscoelastic performance of a circular dielectric elastomer(DE) membrane actuator containing an inclusion is investigated in the context of the nonlinear theory for viscoelastic dielectrics. The membrane, a key part of the actuator, is centrally attached to a rigid inclusion of the radius a, and then connected to a fixed rigid ring of the radius b. When subject to a pressure and a voltage, the membrane inflates into an out-of-plane shape and undergoes an inhomogeneous large deformation. The governing equations for the large deformation are derived by means of non-equilibrium thermodynamics, and viscoelasticity of the membrane is characterized by a rheological spring-dashpot model. In the simulation, effects of the pressure, the voltage, and design parameters on the electromechanical viscoelastic behaviors of the membrane are investigated. Evolutions of the considered variables and profiles of the deformed membrane are obtained numerically and illustrated graphically. The results show that electromechanical loadings and design parameters significantly influence the electro-viscoelastic behaviors of the membrane. The design parameters can be tailored to improve the performance of the membrane. The approach may provide guidelines in designing and optimizing such DE devices.
基金the National Key Research and Development Project of China(2017YFB1002000)the National Natural Science Foundation of China(Grant Nos.61602067 and 61872050)+2 种基金the Fundamental Research Funds for the Central Universities(2018cdqyjsj0024)the Chongqing Basic and Frontier Research Program(cstc2018jcyj AX0551)the Frontier Interdisciplinary Research Funds for the Central Universities(106112017cdjqj188828)。
文摘Traditional route planners commonly focus on finding the shortest path between two points in terms of travel distance or time over road networks.However,in real cases,especially in the era of smart cities where many kinds of transportation-related data become easily available,recent years have witnessed an increasing demand of route planners that need to optimize for multiple criteria,e.g.,finding the route with the highest accumulated scenic score along(utility)while not exceeding the given travel time budget(cost).Such problem can be viewed as a variant of arc orienteering problem(AOP),which is well-known as an NP-hard problem.In this paper,targeting a more realistic AOP,we allow both scenic score(utility)and travel time(cost)values on each arc of the road network are time-dependent(2TD-AOP),and propose a memetic algorithm to solve it.To be more specific,within the given travel time budget,in the phase of initiation,for each population,we iteratively add suitable arcs with high scenic score and build a path from the origin to the destination via a complicate procedure consisting of search region narrowing,chromosome encoding and decoding.In the phase of the local search,each path is improved via chromosome selection,local-improvement-based mutation and crossover operations.Finally,we evaluate the proposed memetic algorithm in both synthetic and real-life datasets extensively,and the experimental results demonstrate that it outperforms the baselines.
基金Discussions with Wolfgang Bangerth,Sverker Holmgren,Hans O.Karlsson,Emil Kieri,Martin Kronbichler,and Axel Malqvist are gratefully acknowledged.Most of the work was performed under the previous affiliation of the author at the Department of Information Technology,Uppsala University,and the computationswere performed on resources provided by SNIC through Uppsala Multidisciplinary Center for Advanced Computational Science(UPPMAX)under projects p2003013 and p2005005.
文摘In this paper,we present a discretization of the time-dependent Schrodinger equation based on a Magnus-Lanczos time integrator and high-order Gauss-Lobatto finite elements in space.A truncated Galerkin orthogonality is used to obtain dualitybased a posteriori error estimates that address the temporal and the spatial error separately.Based on this theory,a space-time adaptive solver for the Schrodinger equation is devised.An efficient matrix-free implementation of the differential operator,suited for spectral elements,is used to enable computations for realistic configurations.We demonstrate the performance of the algorithm for the example of matter-field interaction.
基金Project supported by the National Natural Science Foundation of China(Nos.11632011,11572189,and 51421092)the China Postdoctoral Science Foundation(No.2016M601585)
文摘A novel method based on time-dependent stochastic orthogonal bases for stochastic response surface approximation is proposed to overcome the problem of significant errors in the utilization of the generalized polynomial chaos(GPC) method that approximates the stochastic response by orthogonal polynomials. The accuracy and effectiveness of the method are illustrated by different numerical examples including both linear and nonlinear problems. The results indicate that the proposed method modifies the stochastic bases adaptively, and has a better approximation for the probability density function in contrast to the GPC method.
基金supported by the contracts PNCDI2-Parteneriate 71-112 and PN09370102 of the Romanian Ministry of Education and Research.
文摘The emission of scission neutrons from fissioning nuclei is of high practical interest.To study this process we have used the sudden approximation and also a more realistic approach that takes into account the scission dynamics.Numerically,this implies the solution of the bi-dimensional Schr¨odinger equation,both stationary and time-dependent.To describe axially symmetric extremely deformed nuclear shapes,we have used the Cassini parametrization.The Hamiltonian is discretized by using finite difference approximations of the derivatives.The main computational challenges are the solution of algebraic eigenvalue problems and of linear systems with large sparse matrices.We have employed appropriate procedures(Arnoldi and bi-conjugate gradients).The numerical solutions have been used to evaluate physical quantities,like the number of emitted neutrons per scission event,the primary fragments’excitation energy and the distribution of the emission points.
文摘In this article,a theoretical analysis on flow in a curvilinear horizontal coaxial cylinder with permeable walls has been proposed.Specifically,the transient impact of an oscillating pressure gradient has been taken into account.The non-linear time-dependent partial differential equation accountable for the flow has been transformed using the classical Laplace transform technique.Exact solution of the momentum equation has been obtained in Laplace domain.Due to the intricacy of the Laplace domain solutions,a numerical inversing technique which is established upon the Riemann-sum approximation(RSA)has been utilized to transform the Laplace domain solutions to time domain.Findings reveal that the outcome of suction on the porous walls and boosting the frequency of oscillation renders skin frictions on both walls of the cylinder less effective.The instability of the Dean vortices in the annular gap can be suppressed by amplifying the frequency of oscillating pressure gradient while time is maintained.
文摘Based on the Morlet complex wavelet transformation,the authors put forward a kind of new method for distinguishing periods of seismic activity and quietude and a new physical thought on the time-dependent wavelet accumulation energy spectrum with periods, the time-frequency distribution of wavelet vibration period spectrum and period-specific wavelet vibration spectrum. By applying the above methods to a time series which is composed of earthquake accumulation energy per year for the world, the Chinese continent and North China, respectively, we obtained some new information about the rhythm of shallow earthquake activity. Considering the historic earthquakes and the rhythm characteristics of current strong earthquake activity, the earthquake tendency in the next years is discussed.
基金This work was supported by the National Natural Science Foundation of China （No.21033002 and No.20803066） and the National Basic Research Program of China （No.2007CB815203）.
文摘The A-band resonance Raman spectra of thiourea were obtained in water and acetonitrile solution. B3LYP/6-311＋＋G（3df,3pd） and RCIS/6-311＋＋G（3df,3pd） calculations were done to elucidate the ultraviolet electronic transitions, the distorted geometry structure and the saddle point of thiourea in 21A excited state, respectively. The resonance Raman spectra were assigned. The absorption spectrum and resonance Raman intensities were modeled using Heller＇s time-dependent wavepacket approach to resonance Raman scattering. The results indicate that largest change in the displacement takes place with the C--S stretch mode u6 （｜△｜=0.95） and noticeable changes appear in the H5N3H6＋H8N4H7 wag v5 （｜△｜=0.19）, NCN symmetric stretch^-C--S stretch＋N3H6＋H8N4 wag v4 （｜△｜=0.18）, while the moderate intensities of 2-15 and 4-15 are mostly due to the large excited state frequency changes of v15, but not due to its significant change in the normal mode displacement. The mechanism of the appearance of even overtones of the S-CN2 out of plane deformation is explored. The results indicate that a Franck-Condon region saddle point is the driving force for the quadric phonon mechanism within the standard A-term of resonance Raman scattering, which leads to the pyramidalization of the carbon center and the geometry distortion of thiourea molecule in 21A excited state.
基金National Science Foundation of China under Grant 11072113.
文摘In this work,vortex convection is simulated using a dynamic mesh adaptation procedure.In each adaptation period,the mesh is refined in the regions where the phenomena evolve and is coarsened in the regions where the phenomena deviate since the last adaptation.A simple indicator of mesh adaptation that accounts for the solution progression is defined.The generation of dynamic adaptive meshes is based on multilevel refinement/coarsening.The efficiency and accuracy of the present procedure are validated by simulating vortex convection in a uniform flow.Two unsteady compressible turbulent flows involving blade-vortex interactions are investigated to demonstrate further the applicability of the procedure.Computed results agree well with the published experimental data or numerical results.
