由于光伏电池的输出特性会随着环境变化而改变,因此,合理的最大功率点跟踪(maximum power point tracking, MPPT)技术是提高光伏发电系统效率的关键.但在定步长算法中,跟踪速度和稳态精度之间存在固有矛盾,而传统变步长算法在光照变化...由于光伏电池的输出特性会随着环境变化而改变,因此,合理的最大功率点跟踪(maximum power point tracking, MPPT)技术是提高光伏发电系统效率的关键.但在定步长算法中,跟踪速度和稳态精度之间存在固有矛盾,而传统变步长算法在光照变化下缺乏灵活性,起动速度慢,制约了MPPT的跟踪质量.针对此问题,提出一种优化的变步长电导增量法.该算法可根据工作点位置选取合理的跟踪比例系数,克服了传统变步长算法动态响应速度慢、精度不高的问题.在Matlab/Simulink下的仿真结果证实了该算法在变化的光照情况下的可行性.展开更多
宽幅干涉(terrain observation by progressive scans,TOPS)模式方位向多普勒中心频率的变化导致了干涉图相位的相对扭曲,干涉处理时需要较高的配准精度。加拿大合成孔径雷达遥感卫星(RADARSAT-2)TOPS模式影像由于轨道精度较差,几何配...宽幅干涉(terrain observation by progressive scans,TOPS)模式方位向多普勒中心频率的变化导致了干涉图相位的相对扭曲,干涉处理时需要较高的配准精度。加拿大合成孔径雷达遥感卫星(RADARSAT-2)TOPS模式影像由于轨道精度较差,几何配准精度过低,导致其干涉配准较哨兵合成孔径雷达遥感(Sentinel-1)卫星更加复杂。为了实现该卫星TOPS模式影像的干涉处理,首先采用相关配准、谱分集方法依次对几何配准结果进行校正,然后利用增强谱分集进行方位向偏移量矫正。由于依靠卫星星历参数和聚焦成像参数的多普勒中心估计方法精度有限,因此提出了采用相位增量法优化多普勒中心估计结果,并通过影像方位线功率谱检验了估计的多普勒中心。展开更多
X-ray pulsars offer stable, periodic X-ray pulse sequences that can be used in spacecraft positioning systems. A method using X-ray pulsars to determine the initial orbit of a satellite is presented in this paper. Thi...X-ray pulsars offer stable, periodic X-ray pulse sequences that can be used in spacecraft positioning systems. A method using X-ray pulsars to determine the initial orbit of a satellite is presented in this paper. This method suggests only one detector to be equipped on the satellite and assumes that the detector observes three pulsars in turn. To improve the performance, the use of incremental phase in one observation duration is proposed, and the incremental phase is combined with the time difference of arrival(TDOA). Then, a weighted least squares(WLS) algorithm is formulated to calculate the initial orbit. Numerical simulations are performed to assess the proposed orbit determination method.展开更多
文摘由于光伏电池的输出特性会随着环境变化而改变,因此,合理的最大功率点跟踪(maximum power point tracking, MPPT)技术是提高光伏发电系统效率的关键.但在定步长算法中,跟踪速度和稳态精度之间存在固有矛盾,而传统变步长算法在光照变化下缺乏灵活性,起动速度慢,制约了MPPT的跟踪质量.针对此问题,提出一种优化的变步长电导增量法.该算法可根据工作点位置选取合理的跟踪比例系数,克服了传统变步长算法动态响应速度慢、精度不高的问题.在Matlab/Simulink下的仿真结果证实了该算法在变化的光照情况下的可行性.
文摘宽幅干涉(terrain observation by progressive scans,TOPS)模式方位向多普勒中心频率的变化导致了干涉图相位的相对扭曲,干涉处理时需要较高的配准精度。加拿大合成孔径雷达遥感卫星(RADARSAT-2)TOPS模式影像由于轨道精度较差,几何配准精度过低,导致其干涉配准较哨兵合成孔径雷达遥感(Sentinel-1)卫星更加复杂。为了实现该卫星TOPS模式影像的干涉处理,首先采用相关配准、谱分集方法依次对几何配准结果进行校正,然后利用增强谱分集进行方位向偏移量矫正。由于依靠卫星星历参数和聚焦成像参数的多普勒中心估计方法精度有限,因此提出了采用相位增量法优化多普勒中心估计结果,并通过影像方位线功率谱检验了估计的多普勒中心。
基金supported by the National Natural Science Foundation of China(No.61401340)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2016JM6035)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.JB161303)and the Areospace T.T.&C.Innovation Program(No.201515A)
文摘X-ray pulsars offer stable, periodic X-ray pulse sequences that can be used in spacecraft positioning systems. A method using X-ray pulsars to determine the initial orbit of a satellite is presented in this paper. This method suggests only one detector to be equipped on the satellite and assumes that the detector observes three pulsars in turn. To improve the performance, the use of incremental phase in one observation duration is proposed, and the incremental phase is combined with the time difference of arrival(TDOA). Then, a weighted least squares(WLS) algorithm is formulated to calculate the initial orbit. Numerical simulations are performed to assess the proposed orbit determination method.
