Advantages of the multinucleon transfer reactions based on 238U target for producing neutron-rich isotopes around N = 126

The mechanism of multinucleon transfer (MNT) reactions for producing neutron-rich heavy nuclei around N = 126 is investigated within two different theoretical frameworks: dinuclear system (DNS) model and isospin-dependent quantum molecular dynamics (IQMD) model. The effects of mass asymmetry relaxation, N=Z equilibration, and shell closures on production cross sections of neutron-rich heavy nuclei are investigated. For the first time, the advantages for producing neutron-rich heavy nuclei around N = 126 is found in MNT reactions based on 238U target. We propose the reactions with 238U target for producing unknown neutron-rich heavy nuclei around N = 126 in the future.Comment: 6 pages, 6 figure

A general method for designing the transformer of flyback converters based on nonlinear FEA of electromagnetic field coupled with external circuit

This paper presents a general method for designing the transformer of flyback switching AC-DC converters based on nonlinear finite element analysis (FEA) of electromagnetic field coupled with external circuit. For that, the variation patterns of the PWM duty ratio and the current flowing through the windings of transformer versus the input voltage are introduced first, and then several important principles for the design of the transformer are given by using analytical method. As the magnetic saturation and control delay possess heavy influence on the safety of the operation, a MATLAB/Simulink based simulation model, in which both the nonlinear differential inductance and the control delay are included, is built to predict the converter transient performance. The nonlinear differential inductance is calculated by a general program of nonlinear 2-D FEA in Matlab/Simulink surrounding. By running the model, the performances of the converter with different loads and input voltages are obtained. Simulation results are in good agreement with theoretical analysis

An improved phase variable model based on electro-magnetic field coupled with its external circuits for performance evaluation of permanent magnet brushless DC motors

This paper presents the comprehensive performance evaluation of a brushless permanent magnet (PM) DC (BLDC) motor in dynamic conditions by an improved phase variable model based on electro-magnetic field coupled with its external circuits. In the proposed model, the inductances, back electromotive force (emf) and cogging torque are obtained by nonlinear finite element analysis (FEA). The phase variable model is built and implemented in the MATLAB/Simulink through a method of look-up table to decide the emf which depends on rotor position. Further more, based on a mathematical function for the decision to the voltage of the three phase winding central point, the model could not only solve the problem to decide the input voltage of the phase which is in a non-energized condition, and also make the transient current process during the commutation clear. The theoretical verification is also given in detail. By using the developed model, the comprehensive performance of BLDC motors could be investigated. ©2007 IEEE

Modeling and performance analysis of energy regeneration system in electric vehicle with permanent magnet DC motor driving system

This paper presents the modeling and performance analysis of energy regeneration system (ERS) of electric vehicle with permanent magnet DC motor driving system. Based on the boost equivalent circuit with average current mode controlled ERS, a detailed switching model (DSM) is built to predict the dynamical performance. The DSM includes four blocks: system dynamics block, permanent magnet DC motor block, boost converter block and system performance calculation block. An automatic mechanism of linearizing the nonlinear system at the local operating point is enrolled to obtain the small signal average model (SSAM) of ERS, by which the frequency domain performance can be acquired. The proposed models are implemented in MATLAB/Simulink. By running the simulation model, several important performances of ERS are obtained