1,366 research outputs found
Meshing Force of Misaligned Spline Coupling and the Influence on Rotor System
Meshing force of misaligned spline coupling is derived, dynamic equation of rotor-spline coupling system is established based on finite element analysis, the influence of meshing force on rotor-spline coupling system is simulated by numerical integral method. According to the theoretical analysis, meshing force of spline coupling is related to coupling parameters, misalignment, transmitting torque, static misalignment, dynamic vibration displacement, and so on. The meshing force increases nonlinearly with increasing the spline thickness and static misalignment or decreasing alignment meshing distance (AMD). Stiffness of coupling relates to dynamic vibration displacement, and static misalignment is not a constant. Dynamic behaviors of rotor-spline coupling system reveal the following: 1X-rotating speed is the main response frequency of system when there is no misalignment; while 2X-rotating speed appears when misalignment is present. Moreover, when misalignment increases, vibration of the system gets intricate; shaft orbit departs from origin, and magnitudes of all frequencies increase. Research results can provide important criterions on both optimization design of spline coupling and trouble shooting of rotor systems
Theoretical study of the synthesis of superheavy nuclei with Z= 119 and 120 in heavy-ion reactions with trans-uranium targets
By using a newly developed di-nuclear system model with a dynamical potential
energy surface---the DNS-DyPES model, hot fusion reactions for synthesizing
superheavy nuclei (SHN) with the charge number Z = 112-120 are studied. The
calculated evaporation residue cross sections are in good agreement with
available data. In the reaction 50Ti+249Bk -> (299-x)119 + xn, the maximal
evaporation residue (ER) cross section is found to be about 0.11 pb for the
4n-emission channel. For projectile-target combinations producing SHN with
Z=120, the ER cross section increases with the mass asymmetry in the incident
channel increasing. The maximal ER cross sections for 58Fe+244Pu and 54Cr +
248Cm are relatively small (less than 0.01 pb) and those for 50Ti+249Cf and
50Ti+251Cf are about 0.05 and 0.25 pb, respectively.Comment: 6 pages, 5 figures; Phys. Rev. C, in pres
Experimental implementation of fully controlled dephasing dynamics and synthetic spectral densities
Engineering, controlling, and simulating quantum dynamics is a strenuous
task. However, these techniques are crucial to develop quantum technologies,
preserve quantum properties, and engineer decoherence. Earlier results have
demonstrated reservoir engineering, construction of a quantum simulator for
Markovian open systems, and controlled transition from Markovian to
non-Markovian regime. Dephasing is an ubiquitous mechanism to degrade the
performance of quantum computers. However, a fully controllable all-purpose
quantum simulator for generic dephasing is still missing. Here we demonstrate
full experimental control of dephasing allowing us to implement arbitrary
decoherence dynamics of a qubit. As examples, we use a photon to simulate the
dynamics of a qubit coupled to an Ising chain in a transverse field and also
demonstrate a simulation of non-positive dynamical map. Our platform opens the
possibility to simulate dephasing of any physical system and study fundamental
questions on open quantum systems.Comment: V2: Added some text and new figur
Experimental Trapped-ion Quantum Simulation of the Kibble-Zurek dynamics in momentum space
The Kibble-Zurek mechanism is the paradigm to account for the nonadiabatic
dynamics of a system across a continuous phase transition. Its study in the
quantum regime is hindered by the requisite of ground state cooling. We report
the experimental quantum simulation of critical dynamics in the
transverse-field Ising model by a set of Landau-Zener crossings in
pseudo-momentum space, that can be probed with high accuracy using a single
trapped ion. We test the Kibble-Zurek mechanism in the quantum regime in the
momentum space and find the measured scaling of excitations is in accordance
with the theoretical prediction.Comment: 10 pages, 3 figures Published in Scientific Reports,
http://www.nature.com/articles/srep3338
Structures and photoelectron spectroscopy of Cu-n(BO2)(m) - (n, m=1, 2) clusters: Observation of hyperhalogen behavior
The electronic structures of CuBO2 −, Cu(BO2)2 −, Cu2(BO2)−, and Cu2(BO2)2 − clusters were investigated using photoelectron spectroscopy. The measured vertical and adiabatic detachment energies of these clusters revealed unusual properties of Cu(BO2)2 cluster. With an electron affinity of 5.07 eV which is larger than that of its BO2 superhalogen (4.46 eV) building-block, Cu(BO2)2 can be classified as a hyperhalogen. Density functional theory based calculations were carried out to identify the ground stategeometries and study the electronic structures of these clusters. Cu(BO2) and Cu(BO2)2 clusters were found to form chainlike structures in both neutral and anionic forms. Cu2(BO2) and Cu2(BO2)2 clusters, on the other hand, preferred a chainlike structure in the anionic form but a closed ringlike structure in the neutral form. Equally important, substantial differences between adiabatic detachment energies and electron affinities were found, demonstrating that correct interpretation of the experimental photoelectron spectroscopy data requires theoretical support not only in determining the ground stategeometry of neutral and anionic clusters, but also in identifying their low lying isomers
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