Current Issue : April - June Volume : 2019 Issue Number : 2 Articles : 5 Articles
A novel technique of symmetric type quasi-linear electron pulse duration\nmodulation is proposed. The salient feature from the conventional photoelectron\ngun is the introduction of the alternating electric field resonator. The\nelectric field that results is synchronously controlled to generate the desired\nquasi-linear differential energy modulation on the electron pulse passing\nthrough. The effect resulted directly is that the leading electrons undergo negative\nenergy modulation and decelerate, while the rear ones positive energy\nmodulation and accelerate, which eventually leads to electron-pulse-duration\nmodulation. The technical details are demonstrated....
--NA--...
A novel step-up DC-DC converter with a three-winding-coupled-inductor which integrates\na coupled-inductor and voltage-boost techniques for a distributed generation system is proposed\nin this paper. The two windings of the dotted terminal connection are charged by the input source;\nthe proposed converter utilized smaller turn ratios, and can achieve higher gain when the active\nswitch is turned on. The passive lossless clamped circuits not only can absorb the leakage energy,\nbut also lower the switch voltage stresses; additionally, the reverse-recovery problem of diodes can\nbe reduced to improve the system efficiency. Furthermore, the voltage stress of the output capacitor\nis reduced. The operating principle and corresponding theoretical analyses are discussed in detail.\nFinally, an experimental prototype with 50 kHz switching frequency, 40 V input voltage, 380 V output\nvoltage and 400W output power is set up to verify the validity of the proposed converter....
The Lienard-Wiechert 4-potential depends on local coordinates and on retarded\ncoordinates of a charge at the source. Therefore, the 4-potential of incoming\nradiation fields (namely, a photon) cannot be written as a 4-vector.....................
The saturated-core fault current limiter (SFCL) is widely used to limit the fault current.\nHowever, in the conventional SFCL structure, alternating current (AC) and direct current (DC) coils\nare wound on different loosely coupled cores. Owing to the leakage inductance, the traditional\nstructure demonstrates relatively large demand for DC excitation power and excessive impedance\nduring saturation. In this study, a new structure for winding closely coupled DC and AC coils\non the same core in three phases is proposed to reduce the influence of leakage reactance on\nthe SFCL performance. The leakage magnetic flux generated by both structures is analyzed by\nperforming finite element analysis simulations and utilizing a magnetic field division method.\nThe impedance of the limiter is measured at different DC currents and air gaps to optimize its\ndynamic performance. A fabricated prototype of the proposed limiter exhibits smaller steady-state\nlosses and high current-limiting capability....
Loading....