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利用升阶法研究了一类高阶线性变系数常微分方程,给出了齐次方程的通解公式,并讨论了非齐次方程待定的特解. 相似文献
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HJ-1C 卫星是我国第1 颗民用合成孔径雷达卫星,具有条带和扫描两种工作模式。该文根据HJ-1C 卫星ScanSAR 模式的工作特点,在ECS 成像算法和传统斜距多普勒定位方法基础上,提出一种适用于ScanSAR 的等效RD 几何校正方法。首先根据方位时刻关系进行方位拼接,然后根据斜距关系拼接各个子带,接着拟合等效参数,进行斜距多普勒定位,最后实现ScanSAR 图像的几何校正。HJ-1C 卫星的实际数据实验结果表明:HJ-1C 卫星ScanSAR 模式的定位精度可以达到100 m; 24 核CPU 并行情况下实现10 s 处理完一景图像。 相似文献
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Design of high-repetition frequency gating circuit for cathode of image intensifier北大核心CSCD 下载免费PDF全文
According to the requirements of high repetition frequency, fast edge speed and small pulse width for cathode gating signal by range-gated technology, a cathode high repetition frequency gating circuit using period and multi-stage acceleration was proposed. By combining the RC circuit and the high-speed gate circuit, the time bias circuit unit was cascaded to generate logic pulses with different time sequences, which could respectively control the intermediate stage drive MOSFET to generate three phased drive signals, and the output of the intermediate stage drive was used as input of the output-stage MOSFET to control the acceleration and retention of its on-off process. It was verified by software simulation and board-level test. The test results show that the proposed gating circuit can increase the edge time of output pulse from μs level to 2 ns, and can provide +50 V/−200 V cathode off/on voltage, so as to achieve a repetition frequency ranging from 0~350 kHZ, a duty ratio of 0~100%, a minimum pulse width of 3.7 ns, and a pulse output delay time jitter of about 0.1 ns. It has important guiding significance for improving the minimum pulse width performance of high-speed and high-voltage gating power, the highest working repetition frequency and reducing the power loss of the device. © 2022 Editorial office of Journal of Applied Optics. All rights reserved. 相似文献
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