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In this paper, a method for retrieving the line charge density and the current of a downward leader based on ground observations of lightning images and electric field changes was proposed and examined. The method was then applied to two downward negative leaders in a rocket-triggered lightning discharge with measurements of broadband interferometric images and electric field changes at close distance. Only the descending channel portion between about 900–400 m high of the two leaders were analyzed, where the channel was in free air rather than the trace of triggering wire. The line charge density for both leaders showed a general increasing trend with a big impulsive change around 500 m high, as the leaders moved downward, which was in good agreement with the prediction of existing downward leader models. The range of the line charge density was similar for the two leaders (−0.03 to −0.32 mC/m and −0.02 to −0.33 mC/m, respectively). The impulsive change of the line charge density was corresponding to a sharp turn of the leader channel around 500 m high, which may imply that the sharp turn of the leader channel was probably associated with a pre-existing local positive space charge pocket. The estimated leader currents for two leaders ( −20 to −315 A and −77 to −541 A, respectively) were also in good agreement with independent estimations in the literature.

This paper presents a novel approach for an electric-drive-reconstructed onboard charger (EDROC) for electric vehicles incorporating a symmetrical nine-phase permanent magnet machine. To implement three-phase power factor correction and propulsion battery voltage/current regulation, an exclusive utilization of the nine-phase propulsion system is developed. First, a paralleled three-phase pulsewidth-modulated voltage source rectifier is reutilized from six inverter legs and is directly connected to the three-phase utility grid through six-phase out of the machine stator windings. Second, a three-phase buck-type converter is reconstructed by the remaining three-phase inverter legs and machine windings. Third, to realize zero electromagnetic torque production during the three-phase charging mode, the rotor parking position is applied in the decoupling transformation matrix. Moreover, control schemes for a charging mode including current balancing and interleaving strategy are elaborated. To evaluate the steady-state and dynamic behavior of the proposed EDROC system under different operation scenarios, 3.3-kW laboratory prototype based tests have been conducted.

Strontium titanate films with high a -axis orientation [ a ( 100 ) = 94.1 % ] and random orientation were deposited on (111) Pt/Ti/ SiO2/Si substrates by a concentration controlling of the precursor solution during the metal organic deposition process. Topography of samples was investigated by atomic force microscopy after annealing at 800 °C. X-ray diffraction found that the degree of a -axis orientation increased with increasing annealing temperature. The leakage current and the dielectric property were strongly dependent on the film orientation, and the possible causes of orientation dependence were discussed.

2014 International Conference on Lightning Protection, ICLP 2014, Shanghai, 11-18 October 2014