In this paper, we first apply the assumption h=εh' of topographic variation ( h is the nondimensional topographic height and is a small parameter) to obtain nonlinear equations describing three-wave quasi-...In this paper, we first apply the assumption h=εh' of topographic variation ( h is the nondimensional topographic height and is a small parameter) to obtain nonlinear equations describing three-wave quasi-resonant and non-resonant interactions among Rossby waves for zonal wavenumbers 1—3 over a wavenumber-two bottom topography (WTBT). Some numerical calculations are made with the fourth-order Rung-Kutta Scheme. It is found that for the case without topographic forcing, the period of three-wave quasi-resonance (TWQR) is found to be independent of the zonal basic westerly wind, but dependent on the meridional wavenum ber and the initial amplitudes. For the fixed initial data, when the frequency mismatch is smaller and the meridional wavelength is moderate, its period will belong to the 30-60-day period band. However, when the wavenumber-two topography is included, the periods of the forced quasi-resonant Rossby waves are also found to be strongly dependent on the setting of the zonal basic westerly wind. Under the same conditions, only when the zonal basic westerly wind reaches a moderate extent, intraseasonal oscillations in the 30-60-day period band can be found for zonal wavenumbers 1-3. On the other hand, if three Rossby waves considered have the same meridional wavenumber, three-wave non-resonant interaction over a WTBT can occur in this case.When the WTBT vanishes, the amplitudes of these Rossby waves are conserved. But in the presence of a WTBT, the three Rossby waves oscillate with the identical period.The period, over a moderate range of the zonal basic westerly wind, is in the intraseasonal, 30-60-day range.展开更多
The zero-voltage quasi-resonant boost switching DC-DC converter has been inves-tigated by using the time averaging equivalent circuit approach of periodically switching linearnetworks.The DC steady state and AC small ...The zero-voltage quasi-resonant boost switching DC-DC converter has been inves-tigated by using the time averaging equivalent circuit approach of periodically switching linearnetworks.The DC steady state and AC small signal characteristics of the converter are also given.展开更多
提出一种基于Boost拓扑与反激拓扑有机组合思想的Boost-Flyback变换器,Boost环节与反激环节共用输入支路,使电感–变压器的漏感能量得以利用,消除了漏感损耗,并实现了开关管电压钳位,减小了开关管电压应力;Boost与反激环节的输出支路串...提出一种基于Boost拓扑与反激拓扑有机组合思想的Boost-Flyback变换器,Boost环节与反激环节共用输入支路,使电感–变压器的漏感能量得以利用,消除了漏感损耗,并实现了开关管电压钳位,减小了开关管电压应力;Boost与反激环节的输出支路串联,实现了高电压增益;Boost-Flyback变换器输入并联输出串联,进一步提高了变换器的电压增益,同时减小了输入输出电压及电流纹波。提出新拓扑的DCM-ZVS工作模式控制方法,并在开环方式下实现了输出功率的控制。详细分析拓扑的工作原理、电压增益特性及控制方法。通过230 W 30 V/380 V的实验样机验证理论分析的有效性。展开更多
文摘In this paper, we first apply the assumption h=εh' of topographic variation ( h is the nondimensional topographic height and is a small parameter) to obtain nonlinear equations describing three-wave quasi-resonant and non-resonant interactions among Rossby waves for zonal wavenumbers 1—3 over a wavenumber-two bottom topography (WTBT). Some numerical calculations are made with the fourth-order Rung-Kutta Scheme. It is found that for the case without topographic forcing, the period of three-wave quasi-resonance (TWQR) is found to be independent of the zonal basic westerly wind, but dependent on the meridional wavenum ber and the initial amplitudes. For the fixed initial data, when the frequency mismatch is smaller and the meridional wavelength is moderate, its period will belong to the 30-60-day period band. However, when the wavenumber-two topography is included, the periods of the forced quasi-resonant Rossby waves are also found to be strongly dependent on the setting of the zonal basic westerly wind. Under the same conditions, only when the zonal basic westerly wind reaches a moderate extent, intraseasonal oscillations in the 30-60-day period band can be found for zonal wavenumbers 1-3. On the other hand, if three Rossby waves considered have the same meridional wavenumber, three-wave non-resonant interaction over a WTBT can occur in this case.When the WTBT vanishes, the amplitudes of these Rossby waves are conserved. But in the presence of a WTBT, the three Rossby waves oscillate with the identical period.The period, over a moderate range of the zonal basic westerly wind, is in the intraseasonal, 30-60-day range.
文摘The zero-voltage quasi-resonant boost switching DC-DC converter has been inves-tigated by using the time averaging equivalent circuit approach of periodically switching linearnetworks.The DC steady state and AC small signal characteristics of the converter are also given.
文摘提出一种基于Boost拓扑与反激拓扑有机组合思想的Boost-Flyback变换器,Boost环节与反激环节共用输入支路,使电感–变压器的漏感能量得以利用,消除了漏感损耗,并实现了开关管电压钳位,减小了开关管电压应力;Boost与反激环节的输出支路串联,实现了高电压增益;Boost-Flyback变换器输入并联输出串联,进一步提高了变换器的电压增益,同时减小了输入输出电压及电流纹波。提出新拓扑的DCM-ZVS工作模式控制方法,并在开环方式下实现了输出功率的控制。详细分析拓扑的工作原理、电压增益特性及控制方法。通过230 W 30 V/380 V的实验样机验证理论分析的有效性。
