In this paper, a tailored four-step Adams-Bashforth-Moulton (ABM) algorithm is applied to a semirecursive formulation to perform a real-time simulation of a semitrailer truck. In the ABM algorithm, each integration st...In this paper, a tailored four-step Adams-Bashforth-Moulton (ABM) algorithm is applied to a semirecursive formulation to perform a real-time simulation of a semitrailer truck. In the ABM algorithm, each integration step involves two function evaluations, namely predictor and corrector. This is fundamentally different when compared to the classic fourth-order Runge-Kutta (RK) integrator approach that contains four function evaluations. A semitrailer truck under investigation is modeled in term of a semirecursive method and simulated by using the presented ABM algorithm. The results show that the four-step ABM method can reduce CPU time almost 50% for solving the truck dynamics with very similar accuracy, in comparison to the fourth-order RK method. The presented ABM algorithm could be used in the semirecursive formulation to carry out accurate real-time simulation of medium-large vehicle systems.展开更多
In this paper,we develop an exhaustive numerical simulator for the dynamic visualization and behavior prediction of the tether-net system during the whole space debris capture phases,including spread,contact,and close...In this paper,we develop an exhaustive numerical simulator for the dynamic visualization and behavior prediction of the tether-net system during the whole space debris capture phases,including spread,contact,and close.First of all,to perform its geometrically nonlinear deformation,discrete different geometry theory is applied to model the mechanical response of a flexible net.Based on the discretization of the whole structure into multiple vertexes and lines,the internal force and associated Hession are derived in a closed form to solve a series of nonlinear dynamic equations of motion.The spread and deployment of a packaged net can be realized using this well-established net solver.Next,a multidimensional incremental potential formulation is selected to achieve the intersection-free boundary nonlinear contact and collision between the deformable net and rigid debris.Finally,for the closing mechanism analysis,a log-like barrier functional is derived to achieve the nondeviation condition between the ring–rod linkage system.The C2 continuous log barrier functionals constructed for both the contact model and the linkage system are smooth and differentiable,and,therefore,the nonlinear net capture dynamic system can be efficiently solved through a fully implicit time integrator.Overall,as a demonstration,the whole capture process of a defunct satellite using a hexagon net is simulated through our well-established numerical framework.We believe that our comprehensive numerical methods could provide new insight into the optimal design of active debris removal systems and promote further development of the online control of tether tugging systems.展开更多
The effects of tanshinone II A on cell signal transduction system protein kinase B in rats with myocardial hypertrophy induced by the abdominal aorta partial coarctation were investigated.Rat models of myocardial hype...The effects of tanshinone II A on cell signal transduction system protein kinase B in rats with myocardial hypertrophy induced by the abdominal aorta partial coarctation were investigated.Rat models of myocardial hypertrophy were established by using abdom-inal aorta partial coarctation method.Forty-eight rats were randomly divided into sham group(S group),model group(M group),valsartan treatment group(X group),low-dose tanshinone treatment group(LD group),medium-dose tanshinone treatment group(MD group),and high-dose tanshinone treatment group(HD group)(n=8 in each group).Left ventricular mass index(LVMI),left ventri-cular posterior wall(LVPW),and septal thickness(IVS)were detected by high frequency ultrasonography.Myocardialfiber diameter(MFD)was examined by Hematoxylin-Eosin(HE)staining,and the contents of phosphorylated protein kinase B(p-Akt)and p-Gsk3βin myocardium were assayed by Western blot.The results showed that compared with S group,the values of LVMI,LVPW,IVS and MFD were increased in other groups(P<0.05),and the contents of p-Akt,and p-Gsk3βwere also increased in other groups.As compared with MD group,the values of LVMI,LVPW,IVS and MFD were decreased in all treatment groups(P<0.05),and the contents of p-Akt,and p-Gsk3βwere also decreased in all treatment groups.However,there were no significant differences among LD,MD,and HD groups(P>0.05),and there were no significant differences between X group and tanshinone treatment groups(P>0.05).It was suggested that tanshinone II A could prevent myocardial hypertrophy by its action on the Akt signaling pathway.展开更多
This paper investigates an innovative negative-stiffness device(NSD)that modifies the apparent stiffness of the supported structure for seismic isolation.The NSD comprises a lower base on the bottom and a cap on the t...This paper investigates an innovative negative-stiffness device(NSD)that modifies the apparent stiffness of the supported structure for seismic isolation.The NSD comprises a lower base on the bottom and a cap on the top,together with a connecting rod,vertical movable wall,and compressed elastic spring,as well as circumferentially arranged,pretensioned external ropes,and inclined shape memory wires.This configuration can deliver negative stiffness and energy dissipation in any direction within the horizontal plane.A numerical model of the device is developed through a two-step semirecursive method to obtain the force–displacement characteristic relationship.Such a model is first validated through comparison with the results obtained via the commercial software ADAMS.Finally,a large parametric study is performed to assess the role and the influence of each design variable on the overall response of the proposed device.Useful guidelines are drawn from this analysis to guide the system design and optimization.展开更多
基金the National Natural Science Foundation of China (Grant 11702039)the Fundamental Research Funds for the Central Universities of China (Grant 106112017CDJXY330002).
文摘In this paper, a tailored four-step Adams-Bashforth-Moulton (ABM) algorithm is applied to a semirecursive formulation to perform a real-time simulation of a semitrailer truck. In the ABM algorithm, each integration step involves two function evaluations, namely predictor and corrector. This is fundamentally different when compared to the classic fourth-order Runge-Kutta (RK) integrator approach that contains four function evaluations. A semitrailer truck under investigation is modeled in term of a semirecursive method and simulated by using the presented ABM algorithm. The results show that the four-step ABM method can reduce CPU time almost 50% for solving the truck dynamics with very similar accuracy, in comparison to the fourth-order RK method. The presented ABM algorithm could be used in the semirecursive formulation to carry out accurate real-time simulation of medium-large vehicle systems.
基金Natural Science Foundation of Jiangsu Province,China,Grant/Award Number:BK20220794。
文摘In this paper,we develop an exhaustive numerical simulator for the dynamic visualization and behavior prediction of the tether-net system during the whole space debris capture phases,including spread,contact,and close.First of all,to perform its geometrically nonlinear deformation,discrete different geometry theory is applied to model the mechanical response of a flexible net.Based on the discretization of the whole structure into multiple vertexes and lines,the internal force and associated Hession are derived in a closed form to solve a series of nonlinear dynamic equations of motion.The spread and deployment of a packaged net can be realized using this well-established net solver.Next,a multidimensional incremental potential formulation is selected to achieve the intersection-free boundary nonlinear contact and collision between the deformable net and rigid debris.Finally,for the closing mechanism analysis,a log-like barrier functional is derived to achieve the nondeviation condition between the ring–rod linkage system.The C2 continuous log barrier functionals constructed for both the contact model and the linkage system are smooth and differentiable,and,therefore,the nonlinear net capture dynamic system can be efficiently solved through a fully implicit time integrator.Overall,as a demonstration,the whole capture process of a defunct satellite using a hexagon net is simulated through our well-established numerical framework.We believe that our comprehensive numerical methods could provide new insight into the optimal design of active debris removal systems and promote further development of the online control of tether tugging systems.
基金supported by the National Natural Science Foundation of China(Grant No.30500657).
文摘The effects of tanshinone II A on cell signal transduction system protein kinase B in rats with myocardial hypertrophy induced by the abdominal aorta partial coarctation were investigated.Rat models of myocardial hypertrophy were established by using abdom-inal aorta partial coarctation method.Forty-eight rats were randomly divided into sham group(S group),model group(M group),valsartan treatment group(X group),low-dose tanshinone treatment group(LD group),medium-dose tanshinone treatment group(MD group),and high-dose tanshinone treatment group(HD group)(n=8 in each group).Left ventricular mass index(LVMI),left ventri-cular posterior wall(LVPW),and septal thickness(IVS)were detected by high frequency ultrasonography.Myocardialfiber diameter(MFD)was examined by Hematoxylin-Eosin(HE)staining,and the contents of phosphorylated protein kinase B(p-Akt)and p-Gsk3βin myocardium were assayed by Western blot.The results showed that compared with S group,the values of LVMI,LVPW,IVS and MFD were increased in other groups(P<0.05),and the contents of p-Akt,and p-Gsk3βwere also increased in other groups.As compared with MD group,the values of LVMI,LVPW,IVS and MFD were decreased in all treatment groups(P<0.05),and the contents of p-Akt,and p-Gsk3βwere also decreased in all treatment groups.However,there were no significant differences among LD,MD,and HD groups(P>0.05),and there were no significant differences between X group and tanshinone treatment groups(P>0.05).It was suggested that tanshinone II A could prevent myocardial hypertrophy by its action on the Akt signaling pathway.
文摘This paper investigates an innovative negative-stiffness device(NSD)that modifies the apparent stiffness of the supported structure for seismic isolation.The NSD comprises a lower base on the bottom and a cap on the top,together with a connecting rod,vertical movable wall,and compressed elastic spring,as well as circumferentially arranged,pretensioned external ropes,and inclined shape memory wires.This configuration can deliver negative stiffness and energy dissipation in any direction within the horizontal plane.A numerical model of the device is developed through a two-step semirecursive method to obtain the force–displacement characteristic relationship.Such a model is first validated through comparison with the results obtained via the commercial software ADAMS.Finally,a large parametric study is performed to assess the role and the influence of each design variable on the overall response of the proposed device.Useful guidelines are drawn from this analysis to guide the system design and optimization.
