The rapid development of modern science,technology,and industrialization has promoted the birth of more large and complex engineering structures.When the finite element(FE)method is used for dynamic analysis of these ...The rapid development of modern science,technology,and industrialization has promoted the birth of more large and complex engineering structures.When the finite element(FE)method is used for dynamic analysis of these structures,such as high-rise buildings,aircraft,and ships,the structural FE models often contain millions of degrees of freedom.This will lead to great hardware and computing costs,which is often unacceptable in the engineering field.Therefore,many FE model reduction technologies have been developed,among which dynamic condensation and component mode synthesis are the most widely used methods.This paper reviews the historical processes and general theoretical framework of these two main categories of FE model reduction technologies and briefly summarizes the latest applications of these methods in the engineering field.Current bottlenecks in dynamic condensation and component mode synthesis methods,as well as solutions found in literature,are also briefly discussed.Finally,this paper gives a conclusion and brief prospects for future research.This review aims to comprehensively introduce the two most widely used methods of FE model reduction technologies and hopes to provide suggestions and guidance for developing new model reduction technologies.展开更多
We investigated the dynamic evolution and interference phenomena of bubble-shaped Bose-Einstein condensates achievable in a micro-gravity environment.Using numerical solutions of the Gross-Pitaevskii equation describi...We investigated the dynamic evolution and interference phenomena of bubble-shaped Bose-Einstein condensates achievable in a micro-gravity environment.Using numerical solutions of the Gross-Pitaevskii equation describing the dynamic evolution of the bubble-shaped Bose-Einstein condensates,we plotted the evolution of the wave function density distribution on its two-dimensional(2D)cross-section and analysed the resulting patterns.We found that changes in the strength of atomic interactions and initial momentum can affect the dynamic evolution of the bubble-shaped Bose-Einstein condensates and their interference fringes.Notably,we have observed that when the initial momentum is sufficiently high,the thickness of the bubble-shaped Bose-Einstein condensate undergoes a counterintuitive thinning,which is a counterintuitive result that requires further investigation.Our findings are poised to advance our comprehension of the physical essence of bubble-shaped Bose-Einstein condensates and to facilitate the development of relevant experiments in microgravity environments.展开更多
The dynamics of the three coupled dipolar Bose–Einstein condensates containing N bosons is investigated within a mean-field semiclassical picture based on the coherent-state method. Varieties of periodic solutions （...The dynamics of the three coupled dipolar Bose–Einstein condensates containing N bosons is investigated within a mean-field semiclassical picture based on the coherent-state method. Varieties of periodic solutions （configured as vortex, single depleted well, and dimerlike states） are obtained analytically when the fixed points are identified on the N=constant. The system dynamics are studied via numeric integration of trimer motion equations, thus revealing macroscopic effects of population inversion and self-trapping with different initial states. In particular, the trajectory of the oscillations of the populations in each well shows how the dynamics of the condensates are effected by the presence of dipole–dipole interaction and gauge field.展开更多
The Fourier p-element method is an improvement to the finite element method,and is particularly suitable for vibration analysis due to the well-behaved Fourier series.In this paper,an iteration procedure is presented ...The Fourier p-element method is an improvement to the finite element method,and is particularly suitable for vibration analysis due to the well-behaved Fourier series.In this paper,an iteration procedure is presented for solving the resulting nonlinear eigenvalue problem.Three types of Fourier version shape functions are constructed for analyzing the circular shaft torsional vibration,the plate in-plane vibration and annular plate flexural vibration modes,respectively. The numerical results show that this method can achieve higher accuracy and converge much faster than the FEM based on polynomial interpolation,especially for higher mode analysis.展开更多
-Dynamic interaction characteristics of the model deeply embedded platform and foundation soil are studied by means of dynamic substructuring interface transformation synthesis and dynamic condensation. The theoretica...-Dynamic interaction characteristics of the model deeply embedded platform and foundation soil are studied by means of dynamic substructuring interface transformation synthesis and dynamic condensation. The theoretical analysis, computer programs and practical examples are presented; and the results are compared with those obtained by statical condensation method and finite element method.展开更多
A compressible three-phase solver is presented that takes into account the effects of cavitation and condensation dynamics on sprayatomization,near-nozzle flows,and internal flows,particularly in the context of fuel-i...A compressible three-phase solver is presented that takes into account the effects of cavitation and condensation dynamics on sprayatomization,near-nozzle flows,and internal flows,particularly in the context of fuel-injection systems.The computational fluid dynamics solver tracks three phases-the liquid phase of the fuel,the vapor phase of the fuel,and the noncondensable gas into which the fuel is injected-allowing for complete miscibility between the gaseous phases.It uses the volume of fluid method,within a finite-volume framework,to track the interfaces between the fluid components.The solver is then validated for its ability to track interfaces,for mass conservation,and against experimental data of an expected use case,namely,cavitation in an injector.The solver is shown to perform well in all three validation tests.The solver can also be reduced to just a multiphase solver to study cavitation when the third gaseous component may be absent,such as in hydro-turbines.展开更多
Based on the Dyson-Schwinger Equations （DSEs）, the two-quark vacuum condensate, the four-quark vacuum condensate, and the quark gluon mixed vacuum condensate in the non-perturbative QCD vacuum state are investigated...Based on the Dyson-Schwinger Equations （DSEs）, the two-quark vacuum condensate, the four-quark vacuum condensate, and the quark gluon mixed vacuum condensate in the non-perturbative QCD vacuum state are investigated by solving the DSEs with rainbow truncation at zero- and finite- temperature, respectively. These condensates are important input parameters in QCD sum rule with zero and finite temperature, and in studying hadron physics, as well as predicting the quark mean squared momentum rn02- also called quark virtuality in the QCD vacuum state. The present calculated results show that these physical quantities are almost independent of the temperature below the critical point temperature Tc=131 MeV, and above Tc the chiral symmetry is restored. For comparison we calculate the temperature dependence of the ＂in-hadron condensate＂ for pion. At the same time, we also calculate the ratio of the quark gluon mixed vacuum condensate to the two-quark vacuum condensate by using these condensates, and the unknown quark mean squared momentum in the QCD vacuum state has been obtained. The results show that the ratio m2/0（T） is almost fiat in the temperature region from 0 to To, although there are drastic changes of the quark vacuum condensate and the quark gluon mixed vacuum condensate at the region. Our predicted ratio comes out to be m2/0（T）=2.41 GeV2 at the Chiral limit, which is consistent with other theory model predictions, and strongly indicates the significance that the quark gluon mixed vacuum condensate has played in the virtuality calculations.展开更多
基金supported by grants from the National Natural Science Foundation of China(Grant No.11802069)China Postdoctoral Science Foundation(No.3236310534)Heilongjiang Provincial Postdoctoral Science Foun-dation(No.002020830603).
文摘The rapid development of modern science,technology,and industrialization has promoted the birth of more large and complex engineering structures.When the finite element(FE)method is used for dynamic analysis of these structures,such as high-rise buildings,aircraft,and ships,the structural FE models often contain millions of degrees of freedom.This will lead to great hardware and computing costs,which is often unacceptable in the engineering field.Therefore,many FE model reduction technologies have been developed,among which dynamic condensation and component mode synthesis are the most widely used methods.This paper reviews the historical processes and general theoretical framework of these two main categories of FE model reduction technologies and briefly summarizes the latest applications of these methods in the engineering field.Current bottlenecks in dynamic condensation and component mode synthesis methods,as well as solutions found in literature,are also briefly discussed.Finally,this paper gives a conclusion and brief prospects for future research.This review aims to comprehensively introduce the two most widely used methods of FE model reduction technologies and hopes to provide suggestions and guidance for developing new model reduction technologies.
基金the National Key Research and Development Program of China(Grant Nos.2021YFA1400900,2021YFA0718300,and 2021YFA1402100)the National Natural Science Foundation of China(Grant Nos.61835013,12174461,12234012,and 12334012)the Space Application System of China Manned Space Program。
文摘We investigated the dynamic evolution and interference phenomena of bubble-shaped Bose-Einstein condensates achievable in a micro-gravity environment.Using numerical solutions of the Gross-Pitaevskii equation describing the dynamic evolution of the bubble-shaped Bose-Einstein condensates,we plotted the evolution of the wave function density distribution on its two-dimensional(2D)cross-section and analysed the resulting patterns.We found that changes in the strength of atomic interactions and initial momentum can affect the dynamic evolution of the bubble-shaped Bose-Einstein condensates and their interference fringes.Notably,we have observed that when the initial momentum is sufficiently high,the thickness of the bubble-shaped Bose-Einstein condensate undergoes a counterintuitive thinning,which is a counterintuitive result that requires further investigation.Our findings are poised to advance our comprehension of the physical essence of bubble-shaped Bose-Einstein condensates and to facilitate the development of relevant experiments in microgravity environments.
基金Project supported by the National Key Basic Research Special Foundation of China(Grant Nos.2011CB921502,2012CB821305,2009CB930701,and 2010CB922904)the National Natural Science Foundation of China(Grant Nos.10934010,11228409,and 61227902)the National Natural Science Foundation of China–The Research Grants Council(Grant Nos.11061160490 and 1386-N-HKU748/10)
文摘The dynamics of the three coupled dipolar Bose–Einstein condensates containing N bosons is investigated within a mean-field semiclassical picture based on the coherent-state method. Varieties of periodic solutions （configured as vortex, single depleted well, and dimerlike states） are obtained analytically when the fixed points are identified on the N=constant. The system dynamics are studied via numeric integration of trimer motion equations, thus revealing macroscopic effects of population inversion and self-trapping with different initial states. In particular, the trajectory of the oscillations of the populations in each well shows how the dynamics of the condensates are effected by the presence of dipole–dipole interaction and gauge field.
文摘The Fourier p-element method is an improvement to the finite element method,and is particularly suitable for vibration analysis due to the well-behaved Fourier series.In this paper,an iteration procedure is presented for solving the resulting nonlinear eigenvalue problem.Three types of Fourier version shape functions are constructed for analyzing the circular shaft torsional vibration,the plate in-plane vibration and annular plate flexural vibration modes,respectively. The numerical results show that this method can achieve higher accuracy and converge much faster than the FEM based on polynomial interpolation,especially for higher mode analysis.
文摘-Dynamic interaction characteristics of the model deeply embedded platform and foundation soil are studied by means of dynamic substructuring interface transformation synthesis and dynamic condensation. The theoretical analysis, computer programs and practical examples are presented; and the results are compared with those obtained by statical condensation method and finite element method.
文摘A compressible three-phase solver is presented that takes into account the effects of cavitation and condensation dynamics on sprayatomization,near-nozzle flows,and internal flows,particularly in the context of fuel-injection systems.The computational fluid dynamics solver tracks three phases-the liquid phase of the fuel,the vapor phase of the fuel,and the noncondensable gas into which the fuel is injected-allowing for complete miscibility between the gaseous phases.It uses the volume of fluid method,within a finite-volume framework,to track the interfaces between the fluid components.The solver is then validated for its ability to track interfaces,for mass conservation,and against experimental data of an expected use case,namely,cavitation in an injector.The solver is shown to perform well in all three validation tests.The solver can also be reduced to just a multiphase solver to study cavitation when the third gaseous component may be absent,such as in hydro-turbines.
基金Supported by National Natural Science Foundation of China(11365002)Guangxi Natural Science Foundation for Young Researchers(2013GXNSFBB053007,2011GXNSFA018140)+2 种基金Guangxi Education Department(2013ZD049)Guangxi Grant for Excellent Researchers(2011-54)Guangxi University of Science and Technology Foundation for Ph Ds(11Z16)
文摘Based on the Dyson-Schwinger Equations （DSEs）, the two-quark vacuum condensate, the four-quark vacuum condensate, and the quark gluon mixed vacuum condensate in the non-perturbative QCD vacuum state are investigated by solving the DSEs with rainbow truncation at zero- and finite- temperature, respectively. These condensates are important input parameters in QCD sum rule with zero and finite temperature, and in studying hadron physics, as well as predicting the quark mean squared momentum rn02- also called quark virtuality in the QCD vacuum state. The present calculated results show that these physical quantities are almost independent of the temperature below the critical point temperature Tc=131 MeV, and above Tc the chiral symmetry is restored. For comparison we calculate the temperature dependence of the ＂in-hadron condensate＂ for pion. At the same time, we also calculate the ratio of the quark gluon mixed vacuum condensate to the two-quark vacuum condensate by using these condensates, and the unknown quark mean squared momentum in the QCD vacuum state has been obtained. The results show that the ratio m2/0（T） is almost fiat in the temperature region from 0 to To, although there are drastic changes of the quark vacuum condensate and the quark gluon mixed vacuum condensate at the region. Our predicted ratio comes out to be m2/0（T）=2.41 GeV2 at the Chiral limit, which is consistent with other theory model predictions, and strongly indicates the significance that the quark gluon mixed vacuum condensate has played in the virtuality calculations.
