提出一种并联在逆变器交流输出端的单模态六开关Buck-Boost功率耦合电路,以缓冲传统光伏微逆变器中的二次功率脉动。分析了功率耦合电路的四种不同工作模式,主控开关均采用脉冲能量调制(pulse energy modulation,PEM)信号控制。推导了...提出一种并联在逆变器交流输出端的单模态六开关Buck-Boost功率耦合电路,以缓冲传统光伏微逆变器中的二次功率脉动。分析了功率耦合电路的四种不同工作模式,主控开关均采用脉冲能量调制(pulse energy modulation,PEM)信号控制。推导了一个开关周期内不同工作模式下的PEM信号占空比以及耦合电感电流给定值的表达式,用以得到相应的PEM信号脉冲。设计了耦合电感和电容的参数。建立Simulink仿真模型,仿真结果表明,该功率耦合电路不仅能抑制光伏微逆变器直流侧输入电流和母线电压中的二次纹波,而且利用交流输出端电压变化范围大的特点,大大降低耦合电容容值,避免使用短寿命的大电解电容,提高了光伏微逆变器的使用寿命和可靠性。展开更多
Background Pulmonary fungal infection is one type of the common opportunistic infections in AIDS patients. The disease is hard to diagnose because of its complicated imaging features. The objective of this study was t...Background Pulmonary fungal infection is one type of the common opportunistic infections in AIDS patients. The disease is hard to diagnose because of its complicated imaging features. The objective of this study was to investigate the imaging performance characteristics of pulmonary fungal infection in AIDS patients.Methods Fifty-one patients with AIDS complicated with pulmonary fungal infection and 56 patients of non-AIDS with pulmonary fungal infection were examined by CT scans and high-resolution CT scans. The contrast enhanced scans were performed in patients with the mass or suspected enlarged mediastinal lymph nodes. Results were compared between the two groups.Results The most common fungal infection in the two groups of patients was Candida albicans. The infection rates were 54.8% （28 cases） in the group （AIDS patients with pulmonary fungal infection） and 58.3% （32 cases） in another group （non-AIDS patients with pulmonary fungal infection）. In the two groups, the difference in diffuse distribution and the difference in incidence of affected upper and lower lobes in the bilateral lung fields were statistically significant. The differences in patchy or large consolidation shadow, cavitas, enlarged lymph nodes in mediastinum and pleural effusion were also significant when comparing the two groups.Conclusions The lesion in most of AIDS patients with pulmonary fungal infection tends to exhibit diffuse distribution,patchy or large consolidation shadow covering a more extensive region. The differences between AIDS with pulmonary fungal infection and non-AIDS with pulmonary fungal infection are statistically significant in lesion location and complicated imaging features. The most common fungal infection in AIDS patients is Candida albicans.展开更多
文摘提出一种并联在逆变器交流输出端的单模态六开关Buck-Boost功率耦合电路,以缓冲传统光伏微逆变器中的二次功率脉动。分析了功率耦合电路的四种不同工作模式,主控开关均采用脉冲能量调制(pulse energy modulation,PEM)信号控制。推导了一个开关周期内不同工作模式下的PEM信号占空比以及耦合电感电流给定值的表达式,用以得到相应的PEM信号脉冲。设计了耦合电感和电容的参数。建立Simulink仿真模型,仿真结果表明,该功率耦合电路不仅能抑制光伏微逆变器直流侧输入电流和母线电压中的二次纹波,而且利用交流输出端电压变化范围大的特点,大大降低耦合电容容值,避免使用短寿命的大电解电容,提高了光伏微逆变器的使用寿命和可靠性。
文摘Background Pulmonary fungal infection is one type of the common opportunistic infections in AIDS patients. The disease is hard to diagnose because of its complicated imaging features. The objective of this study was to investigate the imaging performance characteristics of pulmonary fungal infection in AIDS patients.Methods Fifty-one patients with AIDS complicated with pulmonary fungal infection and 56 patients of non-AIDS with pulmonary fungal infection were examined by CT scans and high-resolution CT scans. The contrast enhanced scans were performed in patients with the mass or suspected enlarged mediastinal lymph nodes. Results were compared between the two groups.Results The most common fungal infection in the two groups of patients was Candida albicans. The infection rates were 54.8% （28 cases） in the group （AIDS patients with pulmonary fungal infection） and 58.3% （32 cases） in another group （non-AIDS patients with pulmonary fungal infection）. In the two groups, the difference in diffuse distribution and the difference in incidence of affected upper and lower lobes in the bilateral lung fields were statistically significant. The differences in patchy or large consolidation shadow, cavitas, enlarged lymph nodes in mediastinum and pleural effusion were also significant when comparing the two groups.Conclusions The lesion in most of AIDS patients with pulmonary fungal infection tends to exhibit diffuse distribution,patchy or large consolidation shadow covering a more extensive region. The differences between AIDS with pulmonary fungal infection and non-AIDS with pulmonary fungal infection are statistically significant in lesion location and complicated imaging features. The most common fungal infection in AIDS patients is Candida albicans.
