This research deals with the oscillation mechanism of a flip-flop jet nozzle with a connecting tube, based on the measurements of pressures and velocities in the connecting tube and inside the nozzle. The measurements...This research deals with the oscillation mechanism of a flip-flop jet nozzle with a connecting tube, based on the measurements of pressures and velocities in the connecting tube and inside the nozzle. The measurements are carried out varying: 1) the inside diameter d of the connecting tube;2) the length L of the connecting tube and 3) the jet velocity VPN from a primary-nozzle exit. We assume that the jet switches when a time integral reaches a certain value. At first, as the time integral, we introduce the accumulated flow work of pressure, namely, the time integral of mass flux through a connecting tube into the jet-reattaching wall from the opposite jet-un-reattaching wall. Under the assumption, the trace of pressure difference between both the ends of the connecting tube is simply modeled on the basis of measurements, and the flow velocity in the connecting tube is computed as incompressible flow. Second, in order to discuss the physics of the accumulated flow work further, we conduct another experiment in single-port control where the inflow from the control port on the jet-reattaching wall is forcibly controlled and the other control port on the opposite jet-un-reattaching wall is sealed, instead of the experiment in regular jet’s oscillation using the ordinary nozzle with two control ports in connection. As a result, it is found that the accumulated flow work is adequate to determine the dominant jet- oscillation frequency. In the experiment in single-port control, the accumulated flow work of the inflow until the jet’s switching well agrees with that in regular jet’s oscillation using the ordinary nozzle.展开更多
The paper studies the dynamical behaviors of a discrete Logistic system with feedback control. The system undergoes Flip bifurcation and Hopf bifurcation by using the center manifold theorem and the bifurcation theory...The paper studies the dynamical behaviors of a discrete Logistic system with feedback control. The system undergoes Flip bifurcation and Hopf bifurcation by using the center manifold theorem and the bifurcation theory. Numerical simulations not only illustrate our results, but also exhibit the complex dynamical behaviors of the system, such as the period-doubling bifurcation in periods 2, 4, 8 and 16, and quasi-periodic orbits and chaotic sets.展开更多
We present an efficient scheme for the complete analysis of hyperentangled Greenberger–Horne–Zeilinger(GHZ)state in polarization and time-bin degrees of freedom with two steps. Firstly, the polarization GHZ state is...We present an efficient scheme for the complete analysis of hyperentangled Greenberger–Horne–Zeilinger(GHZ)state in polarization and time-bin degrees of freedom with two steps. Firstly, the polarization GHZ state is distinguished completely and nondestructively, resorting to the controlled phase flip(CPF) gate constructed by the cavity-assisted interaction. Subsequently, the time-bin GHZ state is analyzed by using the preserved polarization entanglement. With the help of CPF gate and self-assisted mechanism, our scheme can be directly generalized to the complete N-photon hyperentangled GHZ state analysis, and it may have potential applications in the hyperentanglement-based quantum communication.展开更多
文摘This research deals with the oscillation mechanism of a flip-flop jet nozzle with a connecting tube, based on the measurements of pressures and velocities in the connecting tube and inside the nozzle. The measurements are carried out varying: 1) the inside diameter d of the connecting tube;2) the length L of the connecting tube and 3) the jet velocity VPN from a primary-nozzle exit. We assume that the jet switches when a time integral reaches a certain value. At first, as the time integral, we introduce the accumulated flow work of pressure, namely, the time integral of mass flux through a connecting tube into the jet-reattaching wall from the opposite jet-un-reattaching wall. Under the assumption, the trace of pressure difference between both the ends of the connecting tube is simply modeled on the basis of measurements, and the flow velocity in the connecting tube is computed as incompressible flow. Second, in order to discuss the physics of the accumulated flow work further, we conduct another experiment in single-port control where the inflow from the control port on the jet-reattaching wall is forcibly controlled and the other control port on the opposite jet-un-reattaching wall is sealed, instead of the experiment in regular jet’s oscillation using the ordinary nozzle with two control ports in connection. As a result, it is found that the accumulated flow work is adequate to determine the dominant jet- oscillation frequency. In the experiment in single-port control, the accumulated flow work of the inflow until the jet’s switching well agrees with that in regular jet’s oscillation using the ordinary nozzle.
基金Supported by the Scientific Research Programmes of Colleges in Anhui(KJ2013Z186)
文摘The paper studies the dynamical behaviors of a discrete Logistic system with feedback control. The system undergoes Flip bifurcation and Hopf bifurcation by using the center manifold theorem and the bifurcation theory. Numerical simulations not only illustrate our results, but also exhibit the complex dynamical behaviors of the system, such as the period-doubling bifurcation in periods 2, 4, 8 and 16, and quasi-periodic orbits and chaotic sets.
文摘We present an efficient scheme for the complete analysis of hyperentangled Greenberger–Horne–Zeilinger(GHZ)state in polarization and time-bin degrees of freedom with two steps. Firstly, the polarization GHZ state is distinguished completely and nondestructively, resorting to the controlled phase flip(CPF) gate constructed by the cavity-assisted interaction. Subsequently, the time-bin GHZ state is analyzed by using the preserved polarization entanglement. With the help of CPF gate and self-assisted mechanism, our scheme can be directly generalized to the complete N-photon hyperentangled GHZ state analysis, and it may have potential applications in the hyperentanglement-based quantum communication.
