The geometric formulation of motion of the first-order linear homogenous scleronomous nonholonomic system subjected to active forces is studied with the non- holonomic mapping theory. The quasi-Newton law, the quasi-m...The geometric formulation of motion of the first-order linear homogenous scleronomous nonholonomic system subjected to active forces is studied with the non- holonomic mapping theory. The quasi-Newton law, the quasi-momentum theorem, and the second kind Lagrange equation of dynamical systems are obtained in the Riemann- Cartan configuration spaces. By the nonholonomic mapping, a Euclidean configuration space or a Riemann configuration space of a dynamical system can be mapped into a Riemann-Cartan configuration space with torsion. The differential equations of motion of the dynamical system can be obtained in its Riemann-Cartan configuration space by the quasi-Newton law or the quasi-momentum theorem. For a constrained system~ the differential equations of motion in its Riemann-Cartan configuration space may be sim- pler than the equations in its Euclidean configuration space or its Riemann configuration space. Therefore, the nonholonomic mapping theory can solve some constrained prob- lems, which are difficult to be solved by the traditional analytical mechanics method. Three examples are given to illustrate the effectiveness of the method.展开更多
The impact force owing to breaking waves is one of the important wave loadings exerted on the ocean structures, especially the parts nearby mean sea level (MSL). Since the 1950s, people have proposed a great many meth...The impact force owing to breaking waves is one of the important wave loadings exerted on the ocean structures, especially the parts nearby mean sea level (MSL). Since the 1950s, people have proposed a great many methods to calculate the impact forces exerted on vertical piles. Early experiential formulae were based on the modified Morison equation according to the experiments by Ross and Hall with a drag coefficient 2.5 times larger for shallow water breakers on slender and cylindrical piles. In 1966, the展开更多
We study how can an angular momentum coherent state |τ> keeps its form-invariant during time evolution governed by the Hamiltonian H = f(t)J++ f^*(t)J-+ g(t)Jz. We discuss this topic in the context of boson realiz...We study how can an angular momentum coherent state |τ> keeps its form-invariant during time evolution governed by the Hamiltonian H = f(t)J++ f^*(t)J-+ g(t)Jz. We discuss this topic in the context of boson realization of |τ>. By employing the entangled state representation |ζ> and deriving a new binomial theorem involving two-subscript Hermite polynomials, we derive the wave function <ζ|τ>, which turns out to be a single-subscript Hermite polynomial. Based on this result the maintenance of angular momentum coherent state during time evolution is examined, and the value of τ(t) is totally determined by the parameters involved in the Hamiltonian.展开更多
PETREL, a winged hybrid-driven underwater glider is a novel and practical marine survey platform which combines the features of legacy underwater glider and conventional AUV （autonomous underwater vehicle）. It can b...PETREL, a winged hybrid-driven underwater glider is a novel and practical marine survey platform which combines the features of legacy underwater glider and conventional AUV （autonomous underwater vehicle）. It can be treated as a multi-rigid-body system with a floating base and a particular hydrodynamic profile. In this paper, theorems on linear and angular momentum are used to establish the dynamic equations of motion of each rigid body and the effect of translational and rotational motion of internal masses on the attitude control are taken into consideration. In addition, due to the unique external shape with fixed wings and deflectable rudders and the dual-drive operation in thrust and glide modes, the approaches of building dynamic model of conventional AUV and hydrodynamic model of submarine are introduced, and the tailored dynamic equations of the hybrid glider are formulated. Moreover, the behaviors of motion in glide and thrust operation are analyzed based on the simulation and the feasibility of the dynamic model is validated by data from lake field trials.展开更多
Based on the momentum theorem, the fluid governing equation in a lifting pipe is proposed by use of the method combining theoretical analysis with empirical correlations related to the previous research, and the perfo...Based on the momentum theorem, the fluid governing equation in a lifting pipe is proposed by use of the method combining theoretical analysis with empirical correlations related to the previous research, and the performance of an airlift pump can be clearly characterized by the triangular relationship among the volumetric flux of air, water and solid particles, which are obtained respectively by using numerical calculation. The meso-scale river sand is used as tested particles to examine the theoretical model. Results of the model are compared with the data in three-phase flow obtained prior to the development of the present model, by an independent experimental team that used the physical conditions of the present approach. The analytical error can be controlled within 12% for predicting the volumetric flux of water and is smaller than that （±16%） of transporting solid particles in three-phase flow. The experimental results and computations are in good agreement for air-water two-phase flow within a margin of ±8%. Reasonable agreement justifies the use of the present model for engineering design purposes.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.11772144,11572145,11472124,11572034,and 11202090)the Science and Technology Research Project of Liaoning Province(No.L2013005)+1 种基金the China Postdoctoral Science Foundation(No.2014M560203)the Natural Science Foundation of Guangdong Provience(No.2015A030310127)
文摘The geometric formulation of motion of the first-order linear homogenous scleronomous nonholonomic system subjected to active forces is studied with the non- holonomic mapping theory. The quasi-Newton law, the quasi-momentum theorem, and the second kind Lagrange equation of dynamical systems are obtained in the Riemann- Cartan configuration spaces. By the nonholonomic mapping, a Euclidean configuration space or a Riemann configuration space of a dynamical system can be mapped into a Riemann-Cartan configuration space with torsion. The differential equations of motion of the dynamical system can be obtained in its Riemann-Cartan configuration space by the quasi-Newton law or the quasi-momentum theorem. For a constrained system~ the differential equations of motion in its Riemann-Cartan configuration space may be sim- pler than the equations in its Euclidean configuration space or its Riemann configuration space. Therefore, the nonholonomic mapping theory can solve some constrained prob- lems, which are difficult to be solved by the traditional analytical mechanics method. Three examples are given to illustrate the effectiveness of the method.
基金Project supported by the Notional Natural Science Foundation of China and the Bureau of Resources and Enviromment, Academia Sinica
文摘The impact force owing to breaking waves is one of the important wave loadings exerted on the ocean structures, especially the parts nearby mean sea level (MSL). Since the 1950s, people have proposed a great many methods to calculate the impact forces exerted on vertical piles. Early experiential formulae were based on the modified Morison equation according to the experiments by Ross and Hall with a drag coefficient 2.5 times larger for shallow water breakers on slender and cylindrical piles. In 1966, the
基金Project supported by the National Natural Science Foundation of China(Grant No.11347026)the Natural Science Foundation of Shandong Province,China(Grant Nos.ZR2016AM03 and ZR2017MA011)
文摘We study how can an angular momentum coherent state |τ> keeps its form-invariant during time evolution governed by the Hamiltonian H = f(t)J++ f^*(t)J-+ g(t)Jz. We discuss this topic in the context of boson realization of |τ>. By employing the entangled state representation |ζ> and deriving a new binomial theorem involving two-subscript Hermite polynomials, we derive the wave function <ζ|τ>, which turns out to be a single-subscript Hermite polynomial. Based on this result the maintenance of angular momentum coherent state during time evolution is examined, and the value of τ(t) is totally determined by the parameters involved in the Hamiltonian.
基金supported by the National Natural Science Foundation of China(Grant Nos. 50835006 and 51005161)the Science & Technology Support Planning Foundation of Tianjin(Grant No. 09ZCKFGX03000)the Natural Science Foundation of Tianjin(Grant No. 09JCZDJC23400)
文摘PETREL, a winged hybrid-driven underwater glider is a novel and practical marine survey platform which combines the features of legacy underwater glider and conventional AUV （autonomous underwater vehicle）. It can be treated as a multi-rigid-body system with a floating base and a particular hydrodynamic profile. In this paper, theorems on linear and angular momentum are used to establish the dynamic equations of motion of each rigid body and the effect of translational and rotational motion of internal masses on the attitude control are taken into consideration. In addition, due to the unique external shape with fixed wings and deflectable rudders and the dual-drive operation in thrust and glide modes, the approaches of building dynamic model of conventional AUV and hydrodynamic model of submarine are introduced, and the tailored dynamic equations of the hybrid glider are formulated. Moreover, the behaviors of motion in glide and thrust operation are analyzed based on the simulation and the feasibility of the dynamic model is validated by data from lake field trials.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51374101 and 51474158)the National Basic Research Program of China(973 Program,Grant No.2014CB239203)the Scientific Research Project of Education Department of Hunan Province(Grant No.14B047)
文摘Based on the momentum theorem, the fluid governing equation in a lifting pipe is proposed by use of the method combining theoretical analysis with empirical correlations related to the previous research, and the performance of an airlift pump can be clearly characterized by the triangular relationship among the volumetric flux of air, water and solid particles, which are obtained respectively by using numerical calculation. The meso-scale river sand is used as tested particles to examine the theoretical model. Results of the model are compared with the data in three-phase flow obtained prior to the development of the present model, by an independent experimental team that used the physical conditions of the present approach. The analytical error can be controlled within 12% for predicting the volumetric flux of water and is smaller than that （±16%） of transporting solid particles in three-phase flow. The experimental results and computations are in good agreement for air-water two-phase flow within a margin of ±8%. Reasonable agreement justifies the use of the present model for engineering design purposes.
