This work addresses the saturation influence of control voltage on the occurring of self-excited vibration of maglev vehicle-bridge interaction system, which greatly degrades the stability of the levitation control, d...This work addresses the saturation influence of control voltage on the occurring of self-excited vibration of maglev vehicle-bridge interaction system, which greatly degrades the stability of the levitation control, decreases the ride comfort, and restricts the cost of the whole system. Firstly, the interaction model of vehicle-bridge system is developed. Based on the interaction model, the relationship between the control voltage and vibration frequency is solved. Then, the variation of the effective direct component and fundamental harmonic are discussed. Furthermore, from the perspective of energy transmission between the levitation system and bridge, the principle underlying the self-excited vibration is explored, and the influence on the stability is discussed. Finally, in terms of the variation of the characteristic roots, the influence is analyzed further and some conclusions are obtained. This study provides a theoretical guidance for mastering the self-excited vibration problems.展开更多
By means of both a theory for pressure-induced shifts (PS) of energy spectra and a theory for shifts of energy spectra due to electron-phonon interaction (EPI), the 'pure electronic' PS and the PS due to EPI o...By means of both a theory for pressure-induced shifts (PS) of energy spectra and a theory for shifts of energy spectra due to electron-phonon interaction (EPI), the 'pure electronic' PS and the PS due to EPI of R<SUB>1</SUB> line of GSGG:Cr<SUP>3+</SUP> at 70 K have been calculated, respectively. Their physical origins have been revealed. It is found that the admixture of and base-wavefunctions in the wavefunctions of R<SUB>1</SUB> level of GSGG:Cr<SUP>3+</SUP> at 70 K is remarkable under the normal pressure, and the degree of the admixture rapidly decreases with increasing pressure. The change of the degree of the admixture with the pressure plays a key role for not only the pure electronic PS of R<SUB>1</SUB> line but also the PS of R<SUB>1</SUB> line due to EPI. The detailed calculations and analyses show that the pressure-dependent behaviors of the pure electronic PS of R<SUB>1</SUB> line and the PS of R<SUB>1</SUB> line due to EPI are quite different. It is the combined effect of them that gives rise to the total PS of R<SUB>1</SUB> line, which has satisfactorily explained the experimental data (including a reversal of PS of R<SUB>1</SUB> line). In contributions to PS of R<SUB>1</SUB> line due to EPI at 70 K, the temperature-independent contribution is much larger than the temperature-dependent contribution. The former results from the interaction between the zero-point vibration of the lattice and localized electronic state.展开更多
By means of improved ligand-field theory, the ＂pure electronic＂ pressure-induced shift （PS） and the PS due to electron-phonon interaction （EPI） of R-line of MgO：Cr^3＋ have been calculated, respectively. The ca...By means of improved ligand-field theory, the ＂pure electronic＂ pressure-induced shift （PS） and the PS due to electron-phonon interaction （EPI） of R-line of MgO：Cr^3＋ have been calculated, respectively. The calculated results are in very good agreement with the experimental data. The behaviors of the pure electronic PS of R-line of MgO：Cr^3＋ and the PS of its R-line due to EPI are different. It is the combined effect of them that gives rise to the total PS of R-line, which has satisfactorily explained the experimental results. The comparison between the feature of R-line PS of MgO：Cr^3＋ and that of R1-line PS of ruby has been made.展开更多
基金Projects(11302252,11202230)supported by the National Natural Science Foundation of China
文摘This work addresses the saturation influence of control voltage on the occurring of self-excited vibration of maglev vehicle-bridge interaction system, which greatly degrades the stability of the levitation control, decreases the ride comfort, and restricts the cost of the whole system. Firstly, the interaction model of vehicle-bridge system is developed. Based on the interaction model, the relationship between the control voltage and vibration frequency is solved. Then, the variation of the effective direct component and fundamental harmonic are discussed. Furthermore, from the perspective of energy transmission between the levitation system and bridge, the principle underlying the self-excited vibration is explored, and the influence on the stability is discussed. Finally, in terms of the variation of the characteristic roots, the influence is analyzed further and some conclusions are obtained. This study provides a theoretical guidance for mastering the self-excited vibration problems.
文摘By means of both a theory for pressure-induced shifts (PS) of energy spectra and a theory for shifts of energy spectra due to electron-phonon interaction (EPI), the 'pure electronic' PS and the PS due to EPI of R<SUB>1</SUB> line of GSGG:Cr<SUP>3+</SUP> at 70 K have been calculated, respectively. Their physical origins have been revealed. It is found that the admixture of and base-wavefunctions in the wavefunctions of R<SUB>1</SUB> level of GSGG:Cr<SUP>3+</SUP> at 70 K is remarkable under the normal pressure, and the degree of the admixture rapidly decreases with increasing pressure. The change of the degree of the admixture with the pressure plays a key role for not only the pure electronic PS of R<SUB>1</SUB> line but also the PS of R<SUB>1</SUB> line due to EPI. The detailed calculations and analyses show that the pressure-dependent behaviors of the pure electronic PS of R<SUB>1</SUB> line and the PS of R<SUB>1</SUB> line due to EPI are quite different. It is the combined effect of them that gives rise to the total PS of R<SUB>1</SUB> line, which has satisfactorily explained the experimental data (including a reversal of PS of R<SUB>1</SUB> line). In contributions to PS of R<SUB>1</SUB> line due to EPI at 70 K, the temperature-independent contribution is much larger than the temperature-dependent contribution. The former results from the interaction between the zero-point vibration of the lattice and localized electronic state.
文摘By means of improved ligand-field theory, the ＂pure electronic＂ pressure-induced shift （PS） and the PS due to electron-phonon interaction （EPI） of R-line of MgO：Cr^3＋ have been calculated, respectively. The calculated results are in very good agreement with the experimental data. The behaviors of the pure electronic PS of R-line of MgO：Cr^3＋ and the PS of its R-line due to EPI are different. It is the combined effect of them that gives rise to the total PS of R-line, which has satisfactorily explained the experimental results. The comparison between the feature of R-line PS of MgO：Cr^3＋ and that of R1-line PS of ruby has been made.
