We theoretically investigate the Autler–Townes(AT)splitting in the photoelectron spectrum of four-level ladder K_2 molecule driven by a pump 1-pump 2-probe pulse via employing the time-dependent wave packet approach.The effects of the pump-1 laser intensity and wavelength on AT splitting are studied for the first time.The magnitude of AT splitting increases with increasing the pump-1 laser intensity.The triple splitting with asymmetric profile occurs due to the nonresonant excitation.The triple structure is transformed into a double structure(near-resonant region),and then becomes a peak(far-off resonant region)progressively as the pump-1 laser is detuned from the resonance wavelength,which can be explained in terms of the asymmetric excitation/population of dressed states.The splitting between adjacent peaks and the splitting between the two sideband peaks in the triplet do not change with the pump-1 pulse wavelength.The three peaks shift toward lower energy with the same shift 1/4*△_1 as the pump-1 wavelength changes in near-resonant region.The asymptotic behaviors of AT splitting with the pump-1 laser intensity are interesting in the threshold points of the near-resonant region and the far-off resonant region.
The effect of delay time on photoelectron spectra and state populations of a four-level ladder K2 molecule is investigated by a pump1–pump2–probe pulse via the time-dependent wave packet approach. The periodical motion of the wave packet leads to the periodical change of the photoelectron spectra. The Autler–Townes triple splitting appears at zero delay time, double splitting appears at nonzero delay time between pump1 and pump2 pulses, and no splitting appears at nonzero delay time between pump2 and probe pulses. The periodical change of the state populations with the delay time may be due to the coupling effect between the two pulses. It is found that the selectivity of the state populations may be attained by regulating the delay time. The results can provide an important basis for realizing the optical control of molecules experimentally.
distribution network reconfiguration<&wdkj&>node importance degree<&wdkj&>compound objective function<&wdkj&>hierarchical encoded
With the development of automation in smart grids, network reconfiguration is becoming a feasible approach for improving the operation of distribution systems. A novel reconfiguration strategy was presented to get the optimal configuration of improving economy of the system, and then identifying the important nodes. In this strategy, the objectives increase the node importance degree and decrease the active power loss subjected to operational constraints. A compound objective function with weight coefficients is formulated to balance the conflict of the objectives. Then a novel quantum particle swarm optimization based on loop switches hierarchical encoded was employed to address the compound objective reconfiguration problem. Its main contribution is the presentation of the hierarchical encoded scheme which is used to generate the population swarm particles of representing only radial connected solutions. Because the candidate solutions are feasible, the search efficiency would improve dramatically during the optimization process without tedious topology verification. To validate the proposed strategy, simulations are carried out on the test systems. The results are compared with other techniques in order to evaluate the performance of the proposed method.
[盛义发; 桂卫华; 喻寿益] School of Information Science and Engineering, Central South University, Changsha 410083, China;[周文振; 刘升学; 盛义发] School of Electrical Engineering, University of South China, Hengyang 421001, China
School of Information Science and Engineering, Central South University, China