This paper proposedmethod that combined transmission path analysis(TPA)and empirical mode decomposition(EMD)envelope analysis to solve the vibration problemof an industrial robot.Firstly,the deconvolution filter timed...This paper proposedmethod that combined transmission path analysis(TPA)and empirical mode decomposition(EMD)envelope analysis to solve the vibration problemof an industrial robot.Firstly,the deconvolution filter timedomain TPA method is proposed to trace the source along with the time variation.Secondly,the TPA method positioned themain source of robotic vibration under typically different working conditions.Thirdly,independent vibration testing of the Rotate Vector(RV)reducer is conducted under different loads and speeds,which are key components of an industrial robot.The method of EMD and Hilbert envelope was used to extract the fault feature of the RV reducer.Finally,the structural problems of the RV reducer were summarized.The vibration performance of industrial robots was improved through the RV reducer optimization.From the whole industrial robot to the local RV Reducer and then to the internal microstructure of the reducer,the source of defect information is traced accurately.Experimental results showed that the TPA and EMD hybrid methods were more accurate and efficient than traditional time-frequency analysis methods to solve industrial robot vibration problems.展开更多
Chronic inflammation is a crucial inducerof diabetesvascular complications.Onereason is that high glucose easily induces macrophage activation.1 Macrophages are the principal participants in innate immunity and exist ...Chronic inflammation is a crucial inducerof diabetesvascular complications.Onereason is that high glucose easily induces macrophage activation.1 Macrophages are the principal participants in innate immunity and exist in all human tissues.In pathological vascular,infiltrated macrophages secrete inflammatory factors leading to an increase in plaque stability.?In macrophage polarization,autophagy plays an important role.Enhancement of macrophage autophagy could induce macrophage polarization from the M1 phenotype to M2 phenotype and inhibit inflammatory reactions.3 Our previous research found that high glucose condition promotes miR-32 expression and macrophage M1 polarization,4 but the mechanism of miR-32 promoting macrophage M1 polarization is unclear.In this study,we found that,under a high-glucose condition,miR-32/Mef2d/cAMP signaling promoted M1 macrophage polarization via inhibited autophagy.These results provide a theoretical and experimental basis for the prevention and treatment of T2D vascular inflammation.展开更多
This paper considers weak Galerkin finite element approximations on polygonal/polyhedral meshes for a quasistatic Maxwell viscoelastic model.The spatial discretization uses piecewise polynomials of degree k(k≥1)for t...This paper considers weak Galerkin finite element approximations on polygonal/polyhedral meshes for a quasistatic Maxwell viscoelastic model.The spatial discretization uses piecewise polynomials of degree k(k≥1)for the stress approximation,degree k+1 for the velocity approximation,and degree k for the numerical trace of velocity on the inter-element boundaries.The temporal discretization in the fully discrete method adopts a backward Euler difference scheme.We show the existence and uniqueness of the semi-discrete and fully discrete solutions,and derive optimal a priori error estimates.Numerical examples are provided to support the theoretical analysis.展开更多
Mixed finite element methods are considered for a ferrofluid flow model with magnetization paralleled to the magnetic field.The ferrofluid model is a coupled system of the Maxwell equations and the incompressible Navi...Mixed finite element methods are considered for a ferrofluid flow model with magnetization paralleled to the magnetic field.The ferrofluid model is a coupled system of the Maxwell equations and the incompressible Navier-Stokes equations.By skillfully introducing some new variables,the model is rewritten as several decoupled subsystems that can be solved independently.Mixed finite element formulations are given to discretize the decoupled systems with proper finite element spaces.Existence and uniqueness of the mixed finite element solutions are shown,and optimal order error estimates are obtained under some reasonable assumptions.Numerical experiments confirm the theoretical results.展开更多
In this paper,we consider a modified nonlinear dynamic diffusion(DD)method for convection-diffusion-reaction equations.This method is free of stabilization parameters and capable of precluding spurious oscillations.We...In this paper,we consider a modified nonlinear dynamic diffusion(DD)method for convection-diffusion-reaction equations.This method is free of stabilization parameters and capable of precluding spurious oscillations.We develop a reliable and efficient residual-type a posteriori error estimator,which is robust with respect to the diffusivity parameter.Furthermore,we propose a linearized adaptive DD algorithm based on the a posteriori estimator.Finally,we perform numerical experiments to verify the theoretical analysis and the performance of the adaptive algorithm.展开更多
In this paper,we consider lower order rectangular finite element methods for the sin-gularly perturbed Stokes problem.The model problem reduces to a linear Stokes problemwhen the perturbation parameter is large and de...In this paper,we consider lower order rectangular finite element methods for the sin-gularly perturbed Stokes problem.The model problem reduces to a linear Stokes problemwhen the perturbation parameter is large and degenerates to a mixed formulation of Pois-son's equation as the perturbation parameter tends to zero.We propose two 2D andtwo 3D nonconforming rectangular finite elements,and derive robust discretization errorestimates.Numerical experiments are carried out to verify the theoretical results.展开更多
The depletion of fossil energy and the deterioration of the ecological environment have severely restricted the development of the power industry.Therefore,it is extremely urgent to transform energy production methods...The depletion of fossil energy and the deterioration of the ecological environment have severely restricted the development of the power industry.Therefore,it is extremely urgent to transform energy production methods and vigorously develop renewable energy sources.It is therefore important to ensure the stability and operation of a large multi-energy complementary system,and provide theoretical support for the world’s largest single complementary demonstration project with hydro-wind-PV power-battery storage in Qinghai Province.Considering all the multiple power supply constraints,an optimization scheduling model is established with the objective of minimizing the volatility of output power.As particle swarm optimization(PSO)has a problem of premature convergence and slow convergence in the latter half,combined with niche technology in evolution,a niche particle swarm optimization(NPSO)is proposed to determine the optimal solution of the model.Finally,the multiple stations’coordinated operation is analyzed taking the example of 10 million kilowatt complementary power stations with hydropower,wind power,PV power,and battery storage in the Yellow River Company Hainan prefecture.The case verifies the rationality and feasibility of the model.It shows that complementary operations can improve the utilization rate of renewable energy and reduce the impact of wind and PV power’s volatility on the power grid.展开更多
This paper analyzes two extended finite element methods(XFEMs)for linear quadratic optimal control problems governed by Poisson equation in non-convex domains.We follow the variational discretization concept to discre...This paper analyzes two extended finite element methods(XFEMs)for linear quadratic optimal control problems governed by Poisson equation in non-convex domains.We follow the variational discretization concept to discretize the continuous problems,and apply an XFEM with a cut-off function and a classic XFEM with a fixed enrichment area to discretize the state and co-state equations.Optimal error estimates are derived for the state,co-state and control.Numerical results confirm our theoretical results.展开更多
B cells home to the lymph nodes(LNs)via high endothelial venules(HEVs)under the guidance of chemokines,particularly CXCL13.However,as CXCL13 is not directly made in HEVs,the molecular mechanism mediating B-cell homing...B cells home to the lymph nodes(LNs)via high endothelial venules(HEVs)under the guidance of chemokines,particularly CXCL13.However,as CXCL13 is not directly made in HEVs,the molecular mechanism mediating B-cell homing to LNs has remained unclear.We show here that nuclear factor(NF)-κB-inducing kinase(NIK),a kinase mediating activation of the noncanonical NF-κB pathway,functions in lymphatic endothelial cells(LECs)to regulate B-cell homing to LNs.LEC-conditional deletion of NIK in mice did not affect the integrity or global function of lymphatic vessels but caused a severe reduction in the frequency of B cells in LNs.The LEC-specific NIK deficiency did not affect the survival of B cells or the frequency of B cells in the spleen.B-cell adoptive transfer studies revealed that the LEC-specific NIK deletion impairs the ability of LNs to recruit B cells.We further show that NIK mediates expression of the chemokines CXCL13 and CCL19 in LECs.Although CCL19 is also expressed in blood endothelial cells(BECs),CXCL13 is not produced in BECs.These results suggest that NIK regulates naive B-cell homing to LNs via mediating production of the B-cell homing chemokine CXCL13 in LECs.展开更多
In this paper,an energy-compatibility condition is used for stress optimization in the derivation of new accurate 8-node hexahedral elements for threedimensional elasticity.Equivalence of the proposed hybrid method to...In this paper,an energy-compatibility condition is used for stress optimization in the derivation of new accurate 8-node hexahedral elements for threedimensional elasticity.Equivalence of the proposed hybrid method to an enhanced strains method is established,which makes it easy to extend the method to general nonlinear problems.Numerical tests show that the resultant elements possess high accuracy at coarse meshes,are insensitive to mesh distortions and free from volume locking in the analysis of beams,plates and shells.展开更多
Generation and maintenance of antigen-specific effector and memory T cells are central events in immune responses against infections.We show that TNF receptor-associated factor 2(TRAF2)maintains a survival signaling a...Generation and maintenance of antigen-specific effector and memory T cells are central events in immune responses against infections.We show that TNF receptor-associated factor 2(TRAF2)maintains a survival signaling axis in effector and memory CD8 T cells required for immune responses against infections.This signaling axis involves activation of Tpl2 and its downstream kinase ERK by NF-κB-inducing kinase(NIK)and degradation of the proapoptotic factor Bim.NIK mediates Tpl2 activation by stimulating the phosphorylation and degradation of the Tpl2 inhibitor p105.Interestingly,while NIK is required for Tpl2-ERK signaling under normal conditions,uncontrolled NIK activation due to loss of its negative regulator,TRAF2,causes constitutive degradation of p105 and Tpl2,leading to severe defects in ERK activation and effector/memory CD8 T cell survival.Thus,TRAF2 controls a previously unappreciated signaling axis mediating effector/memory CD8 T cell survival and protective immunity.展开更多
In this paper,we consider parabolic distributed control problems with cost functional of pointwise observation type either in space or in time.First,we show the well-posedness of the optimization problems and derive t...In this paper,we consider parabolic distributed control problems with cost functional of pointwise observation type either in space or in time.First,we show the well-posedness of the optimization problems and derive the first order optimality systems,where the adjoint state can be expressed as the linear combination of solutions to two backward parabolic equations that involve the Dirac delta distribution as source either in space or in time.Second,we use a space-time finite element method to discretize the control problems,where the state variable is approximated by piecewise constant functions in time and continuous piecewise linear polynomials in space,and the control variable is discretized by following the variational discretization concept.We obtain a priori error estimates for the control and state variables with order O(k 12+h)up to a logarithmic factor under the L 2-norm.Finally,we perform several numerical experiments to support our theoretical results.展开更多
Semi-discrete and fully discrete mixedfinite element methods are consid-ered for Maxwell-model-based problems of wave propagation in linear viscoelastic solid.This mixedfinite element framework allows the use of a large...Semi-discrete and fully discrete mixedfinite element methods are consid-ered for Maxwell-model-based problems of wave propagation in linear viscoelastic solid.This mixedfinite element framework allows the use of a large class of exist-ing mixed conformingfinite elements for elasticity in the spatial discretization.In the fully discrete scheme,a Crank-Nicolson scheme is adopted for the approximation of the temporal derivatives of stress and velocity variables.Error estimates of the semi-discrete and fully discrete schemes,as well as an unconditional stability result for the fully discrete scheme,are derived.Numerical experiments are provided to verify the theoretical results.展开更多
A family of conforming mixed finite elements with mass lumping on triangular grids are presented for linear elasticity.The stress field is approximated by symmetric H(div)−Pk(k≥3)polynomial tensors enriched with high...A family of conforming mixed finite elements with mass lumping on triangular grids are presented for linear elasticity.The stress field is approximated by symmetric H(div)−Pk(k≥3)polynomial tensors enriched with higher order bubbles so as to allow mass lumping,and the displacement field is approximated by C−1−Pk−1 polynomial vectors enriched with higher order terms.For both the proposed mixed elements and their mass lumping schemes,optimal error estimates are derived for the stress and displacement in H(div)norm and L 2 norm,respectively.Numerical results confirm the theoretical analysis.展开更多
基金supported by Natural Science Foundation of Hunan Province,(Grant No.2022JJ30147)the National Natural Science Foundation of China (Grant No.51805155)the Foundation for Innovative Research Groups of National Natural Science Foundation of China (Grant No.51621004).
文摘This paper proposedmethod that combined transmission path analysis(TPA)and empirical mode decomposition(EMD)envelope analysis to solve the vibration problemof an industrial robot.Firstly,the deconvolution filter timedomain TPA method is proposed to trace the source along with the time variation.Secondly,the TPA method positioned themain source of robotic vibration under typically different working conditions.Thirdly,independent vibration testing of the Rotate Vector(RV)reducer is conducted under different loads and speeds,which are key components of an industrial robot.The method of EMD and Hilbert envelope was used to extract the fault feature of the RV reducer.Finally,the structural problems of the RV reducer were summarized.The vibration performance of industrial robots was improved through the RV reducer optimization.From the whole industrial robot to the local RV Reducer and then to the internal microstructure of the reducer,the source of defect information is traced accurately.Experimental results showed that the TPA and EMD hybrid methods were more accurate and efficient than traditional time-frequency analysis methods to solve industrial robot vibration problems.
基金supported by the National Natural Science Foundation of China(No.81873651)Natural Science Foundation of Hunan Province,China(No.2021JJ40490,2021JJ70113)Scientific Research Fund Project of Hunan Provincial Health Commission,China(No.20201981,20201901)。
文摘Chronic inflammation is a crucial inducerof diabetesvascular complications.Onereason is that high glucose easily induces macrophage activation.1 Macrophages are the principal participants in innate immunity and exist in all human tissues.In pathological vascular,infiltrated macrophages secrete inflammatory factors leading to an increase in plaque stability.?In macrophage polarization,autophagy plays an important role.Enhancement of macrophage autophagy could induce macrophage polarization from the M1 phenotype to M2 phenotype and inhibit inflammatory reactions.3 Our previous research found that high glucose condition promotes miR-32 expression and macrophage M1 polarization,4 but the mechanism of miR-32 promoting macrophage M1 polarization is unclear.In this study,we found that,under a high-glucose condition,miR-32/Mef2d/cAMP signaling promoted M1 macrophage polarization via inhibited autophagy.These results provide a theoretical and experimental basis for the prevention and treatment of T2D vascular inflammation.
基金This work was supported by the National Natural Science Foundation of China(Grant No.12171340).
文摘This paper considers weak Galerkin finite element approximations on polygonal/polyhedral meshes for a quasistatic Maxwell viscoelastic model.The spatial discretization uses piecewise polynomials of degree k(k≥1)for the stress approximation,degree k+1 for the velocity approximation,and degree k for the numerical trace of velocity on the inter-element boundaries.The temporal discretization in the fully discrete method adopts a backward Euler difference scheme.We show the existence and uniqueness of the semi-discrete and fully discrete solutions,and derive optimal a priori error estimates.Numerical examples are provided to support the theoretical analysis.
基金supported by the National Natural Science Foundation of China(Grant Nos.11971094,12171340).
文摘Mixed finite element methods are considered for a ferrofluid flow model with magnetization paralleled to the magnetic field.The ferrofluid model is a coupled system of the Maxwell equations and the incompressible Navier-Stokes equations.By skillfully introducing some new variables,the model is rewritten as several decoupled subsystems that can be solved independently.Mixed finite element formulations are given to discretize the decoupled systems with proper finite element spaces.Existence and uniqueness of the mixed finite element solutions are shown,and optimal order error estimates are obtained under some reasonable assumptions.Numerical experiments confirm the theoretical results.
基金supported in part by the Education Science Foundation of Chongqing(KJZD-K201900701)project supported by Scientific and Technological Research Program of Chongqing Municipal Education Commission(Grant No.KJZD-M202300705)the National Natural Science Foundation of China(No.12171340).
文摘In this paper,we consider a modified nonlinear dynamic diffusion(DD)method for convection-diffusion-reaction equations.This method is free of stabilization parameters and capable of precluding spurious oscillations.We develop a reliable and efficient residual-type a posteriori error estimator,which is robust with respect to the diffusivity parameter.Furthermore,we propose a linearized adaptive DD algorithm based on the a posteriori estimator.Finally,we perform numerical experiments to verify the theoretical analysis and the performance of the adaptive algorithm.
基金NSF DMS-0609727by the Center for Computational Mathematics and Applications of Penn State+3 种基金Jinchao Xu was also supported in part by NSFC-10501001Alexander H.Humboldt Foundation.Xiaoping Xie was supported by the National Natural Science Foundation of China (10771150)the National Basic Research Program of China (2005CB321701)the program for New Century Excellent Talents in University (NCET-07-0584)
基金supported by the Natural Science Foundation of China (10771150)the National Basic Research Program of China (2005CB321701)the Program for New Century Excellent Talents in University (NCET-07-0584)
文摘In this paper,we consider lower order rectangular finite element methods for the sin-gularly perturbed Stokes problem.The model problem reduces to a linear Stokes problemwhen the perturbation parameter is large and degenerates to a mixed formulation of Pois-son's equation as the perturbation parameter tends to zero.We propose two 2D andtwo 3D nonconforming rectangular finite elements,and derive robust discretization errorestimates.Numerical experiments are carried out to verify the theoretical results.
基金supported in part by the Natural Science Foundation of China under Grant No.10771150the National Basic Research Program of China under Grant No.2005CB321701the Natural Science Foundation of Chongqing City under Grant No.CSTC,2010BB8270
基金The authors are grateful for the anonymous referees for their helpful com- ments. This work was supported in part by The Education Science Foundation of Chongqing （KJ120420）, National Natural Science Foundation of China （11171239）, The Project-sponsored by Scientific Research Foundation for the Returned Overseas Chinese Scholars and Open Fund of Key Laboratory of Mountain Hazards and Earth Surface Processes, CAS.
文摘The depletion of fossil energy and the deterioration of the ecological environment have severely restricted the development of the power industry.Therefore,it is extremely urgent to transform energy production methods and vigorously develop renewable energy sources.It is therefore important to ensure the stability and operation of a large multi-energy complementary system,and provide theoretical support for the world’s largest single complementary demonstration project with hydro-wind-PV power-battery storage in Qinghai Province.Considering all the multiple power supply constraints,an optimization scheduling model is established with the objective of minimizing the volatility of output power.As particle swarm optimization(PSO)has a problem of premature convergence and slow convergence in the latter half,combined with niche technology in evolution,a niche particle swarm optimization(NPSO)is proposed to determine the optimal solution of the model.Finally,the multiple stations’coordinated operation is analyzed taking the example of 10 million kilowatt complementary power stations with hydropower,wind power,PV power,and battery storage in the Yellow River Company Hainan prefecture.The case verifies the rationality and feasibility of the model.It shows that complementary operations can improve the utilization rate of renewable energy and reduce the impact of wind and PV power’s volatility on the power grid.
基金supported by National Natural Science Foundation of China(Grant No.11771312)。
文摘This paper analyzes two extended finite element methods(XFEMs)for linear quadratic optimal control problems governed by Poisson equation in non-convex domains.We follow the variational discretization concept to discretize the continuous problems,and apply an XFEM with a cut-off function and a classic XFEM with a fixed enrichment area to discretize the state and co-state equations.Optimal error estimates are derived for the state,co-state and control.Numerical results confirm our theoretical results.
基金by grants from the National Institutes of Health(GM84459,AI057555,AI104519 and AI64639)This study also used the NIH/NCI-supported resources under award number P30CA016672 at The MD Anderson Cancer CenterSZ was supported by a scholarship from the China Scholarship Council(CSC)under the Grant CSC 201506210393.
文摘B cells home to the lymph nodes(LNs)via high endothelial venules(HEVs)under the guidance of chemokines,particularly CXCL13.However,as CXCL13 is not directly made in HEVs,the molecular mechanism mediating B-cell homing to LNs has remained unclear.We show here that nuclear factor(NF)-κB-inducing kinase(NIK),a kinase mediating activation of the noncanonical NF-κB pathway,functions in lymphatic endothelial cells(LECs)to regulate B-cell homing to LNs.LEC-conditional deletion of NIK in mice did not affect the integrity or global function of lymphatic vessels but caused a severe reduction in the frequency of B cells in LNs.The LEC-specific NIK deficiency did not affect the survival of B cells or the frequency of B cells in the spleen.B-cell adoptive transfer studies revealed that the LEC-specific NIK deletion impairs the ability of LNs to recruit B cells.We further show that NIK mediates expression of the chemokines CXCL13 and CCL19 in LECs.Although CCL19 is also expressed in blood endothelial cells(BECs),CXCL13 is not produced in BECs.These results suggest that NIK regulates naive B-cell homing to LNs via mediating production of the B-cell homing chemokine CXCL13 in LECs.
基金supported in part by the Natural Science Foundation of China(10771150)the National Basic Research Program of China(2005CB321701)the Program for New Century Excellent Talents in University(NCET-07-0584).
文摘In this paper,an energy-compatibility condition is used for stress optimization in the derivation of new accurate 8-node hexahedral elements for threedimensional elasticity.Equivalence of the proposed hybrid method to an enhanced strains method is established,which makes it easy to extend the method to general nonlinear problems.Numerical tests show that the resultant elements possess high accuracy at coarse meshes,are insensitive to mesh distortions and free from volume locking in the analysis of beams,plates and shells.
基金This study was supported by grants from the National Institutes of Health(AI64639 and GM84459)the core facilities of MD Anderson Cancer Center are supported by the NIH/NCI Cancer Center Support Grant(CCSG)P30CA016672.
文摘Generation and maintenance of antigen-specific effector and memory T cells are central events in immune responses against infections.We show that TNF receptor-associated factor 2(TRAF2)maintains a survival signaling axis in effector and memory CD8 T cells required for immune responses against infections.This signaling axis involves activation of Tpl2 and its downstream kinase ERK by NF-κB-inducing kinase(NIK)and degradation of the proapoptotic factor Bim.NIK mediates Tpl2 activation by stimulating the phosphorylation and degradation of the Tpl2 inhibitor p105.Interestingly,while NIK is required for Tpl2-ERK signaling under normal conditions,uncontrolled NIK activation due to loss of its negative regulator,TRAF2,causes constitutive degradation of p105 and Tpl2,leading to severe defects in ERK activation and effector/memory CD8 T cell survival.Thus,TRAF2 controls a previously unappreciated signaling axis mediating effector/memory CD8 T cell survival and protective immunity.
基金supported in part by the Strategic Priority Research Program of Chi-nese Academy of Sciences(Grant No.XDB 41000000)the National Key Basic Research Program(Grant No.2018YFB0704304)+1 种基金the National Natural Science Foundation of China(Grants No.12071468,11671391)Xiaoping Xie was supported in part by the National Natural Science Foundation of China(Grants No.12171340,11771312).
文摘In this paper,we consider parabolic distributed control problems with cost functional of pointwise observation type either in space or in time.First,we show the well-posedness of the optimization problems and derive the first order optimality systems,where the adjoint state can be expressed as the linear combination of solutions to two backward parabolic equations that involve the Dirac delta distribution as source either in space or in time.Second,we use a space-time finite element method to discretize the control problems,where the state variable is approximated by piecewise constant functions in time and continuous piecewise linear polynomials in space,and the control variable is discretized by following the variational discretization concept.We obtain a priori error estimates for the control and state variables with order O(k 12+h)up to a logarithmic factor under the L 2-norm.Finally,we perform several numerical experiments to support our theoretical results.
基金supported in part by National Natural Science Foundation of China(No.11771312).
文摘Semi-discrete and fully discrete mixedfinite element methods are consid-ered for Maxwell-model-based problems of wave propagation in linear viscoelastic solid.This mixedfinite element framework allows the use of a large class of exist-ing mixed conformingfinite elements for elasticity in the spatial discretization.In the fully discrete scheme,a Crank-Nicolson scheme is adopted for the approximation of the temporal derivatives of stress and velocity variables.Error estimates of the semi-discrete and fully discrete schemes,as well as an unconditional stability result for the fully discrete scheme,are derived.Numerical experiments are provided to verify the theoretical results.
基金supported in part by the National Natural Science Foundation of China(Grants 11771312,12171340).
文摘A family of conforming mixed finite elements with mass lumping on triangular grids are presented for linear elasticity.The stress field is approximated by symmetric H(div)−Pk(k≥3)polynomial tensors enriched with higher order bubbles so as to allow mass lumping,and the displacement field is approximated by C−1−Pk−1 polynomial vectors enriched with higher order terms.For both the proposed mixed elements and their mass lumping schemes,optimal error estimates are derived for the stress and displacement in H(div)norm and L 2 norm,respectively.Numerical results confirm the theoretical analysis.
