The motion of the fins and control surfaces of underwater vehicles in a fluid is an interesting and challenging research subject.Typically the effect of fin oscillations on the fluid flow around such a body is highly ...The motion of the fins and control surfaces of underwater vehicles in a fluid is an interesting and challenging research subject.Typically the effect of fin oscillations on the fluid flow around such a body is highly unsteady, generating vortices and requiring detailed analysis of fluid-structure interactions.An understanding of the complexities of such flows is of interest to engineers developing vehicles capable of high dynamic performance in their propulsion and maneuvering.In the present study, a CFD based RANS simulation of a 3-D fin body moving in a viscous fluid was developed.It investigated hydrodynamic performance by evaluating the hydrodynamic coefficients (lift, drag and moment) at two different oscillating frequencies.A parametric analysis of the factors that affect the hydrodynamic performance of the fin body was done, along with a comparison of results from experiments.The results of the simulation were found in close agreement with experimental results and this validated the simulation as an effective tool for evaluation of the unsteady hydrodynamic coefficients of 3-D fins.This work can be further be used for analysis of the stability and maneuverability of fin actuated underwater vehicles.展开更多
The interaction of two coherent counter propagating TE （transverse-electric） and TM （transverse-magnetic） electromagnetic waves with different initial phases in the absorbing plate placed in the regular ideal wave...The interaction of two coherent counter propagating TE （transverse-electric） and TM （transverse-magnetic） electromagnetic waves with different initial phases in the absorbing plate placed in the regular ideal waveguide is considered. The losses of energy of TE and TM waves in the absorbing plate are calculated. Some features of tunnel interference in the absorbing plate in the waveguide are revealed. It is shown that the losses of energy strongly depend on the various parameters describing the interaction of the counter propagating waves. Definitely choosing the parameters we can control the electromagnetic processes in this case.展开更多
We have investigated the dynamics of a protomer coupled to two different decoherent environments,each in a configuration called the spin star configuration.Using the quantum mechanics method,in different situations,we...We have investigated the dynamics of a protomer coupled to two different decoherent environments,each in a configuration called the spin star configuration.Using the quantum mechanics method,in different situations,we obtain the analytical expressions for the transition probability in the protomer system.In thermal equilibrium,there exist well-defined ranges of parameters for which decoherent interaction between the protomer and the environment assists energy transfer in the protomer system,while in pure quantum mechanics states,the decoherent interaction assists energy transfer for an eigenstate but against energy transfer for quantum mechanics averages.In particular,we also find that the dimerization of two bacteriochlorophylls in protomer can always assist energy transfer in certain parameter range,and in the appropriate spin bath energy,the efficiency of energy transport is sensitively depended on the temperature of environments.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.50879014
文摘The motion of the fins and control surfaces of underwater vehicles in a fluid is an interesting and challenging research subject.Typically the effect of fin oscillations on the fluid flow around such a body is highly unsteady, generating vortices and requiring detailed analysis of fluid-structure interactions.An understanding of the complexities of such flows is of interest to engineers developing vehicles capable of high dynamic performance in their propulsion and maneuvering.In the present study, a CFD based RANS simulation of a 3-D fin body moving in a viscous fluid was developed.It investigated hydrodynamic performance by evaluating the hydrodynamic coefficients (lift, drag and moment) at two different oscillating frequencies.A parametric analysis of the factors that affect the hydrodynamic performance of the fin body was done, along with a comparison of results from experiments.The results of the simulation were found in close agreement with experimental results and this validated the simulation as an effective tool for evaluation of the unsteady hydrodynamic coefficients of 3-D fins.This work can be further be used for analysis of the stability and maneuverability of fin actuated underwater vehicles.
文摘The interaction of two coherent counter propagating TE （transverse-electric） and TM （transverse-magnetic） electromagnetic waves with different initial phases in the absorbing plate placed in the regular ideal waveguide is considered. The losses of energy of TE and TM waves in the absorbing plate are calculated. Some features of tunnel interference in the absorbing plate in the waveguide are revealed. It is shown that the losses of energy strongly depend on the various parameters describing the interaction of the counter propagating waves. Definitely choosing the parameters we can control the electromagnetic processes in this case.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11274272,11304281,31201001by the Natural Science Foundation of Zhejiang Province under Grant Nos.Y6110250LY14A040001 and Zhejiang Ocean University(X12ZD10)
文摘We have investigated the dynamics of a protomer coupled to two different decoherent environments,each in a configuration called the spin star configuration.Using the quantum mechanics method,in different situations,we obtain the analytical expressions for the transition probability in the protomer system.In thermal equilibrium,there exist well-defined ranges of parameters for which decoherent interaction between the protomer and the environment assists energy transfer in the protomer system,while in pure quantum mechanics states,the decoherent interaction assists energy transfer for an eigenstate but against energy transfer for quantum mechanics averages.In particular,we also find that the dimerization of two bacteriochlorophylls in protomer can always assist energy transfer in certain parameter range,and in the appropriate spin bath energy,the efficiency of energy transport is sensitively depended on the temperature of environments.
