Based on this equation , the principle of the small - scale self - focusing is further analyzed . this work is called the b - t theory , which is the groundwork of the dissertation 这部分内容被称为线性扰动不稳定性理论，又称b - t理论，它是小尺度自聚焦的理论基础，也是热像研究的理论基础。
Lastly , the dissertation makes a rough comparison between all autofocusing algorithms and points out that the performance of autofocusing is dependent on particular scenes and the characteristics of phase errors 最后，对各种方法进行了比较，指出自聚焦的性能依赖于具体的成像场景及相位误差特性。
In order to fully understand the physical mechanism governing the small - scale self - focusing and extract a guide line to the optimization of drivers , in this work , we discuss some problems about it 为了弄清小尺度自聚焦的物理机制，以便于指导我们更加优化地设计驱动器，本文对这一问题进行了相应的探讨。
On the assumption that imagery pixel follows non - normal distribution in high resolution imaging , a new method of phase errors estimation based on higher - order statistics is proposed for sar imagery autofocusing 在高分辨成像情况下，基于图像像素强度服从非高斯分布的假设，提出了一种基于三阶累积量的自聚焦方法。
Since phase gradient autofocusing ( pga ) often produces unsatisfactory results when operating upon scenes that are dominated by distributed targets , a modified weighting average phase errors estimation method is proposed 针对相邻强目标导致的相位梯度自聚焦算法( pga )收敛速度下降，提出了一种加权平均相位误差估计方法。
Chapter 2 introduces the sources and influences on images of all kinds of phase errors , analyzes existing some autofocusing algorithms and lays stress on considerations for application 论文第二章详细分析了各种相位误差的来源及它们对图像产生的影响，对几种现有的自聚焦算法进行了描述，指出实际应用过程中应该注意的问题。
The simulation data and real sar data validate the result . chapter 3 introduces two different phase error estimation algorithm : shear averaging algorithm and pga ( phase gradient autofocus ) algorithm 第三章具体介绍了两种相位误差估计算法，剪切平均算法( shearaveraging )和相位梯度自聚焦算法( phasegradientautofocus ， pga ) 。
The clinical application indicates that the endoscope is easy to operate and can produce high - quality images , and thus can be applied to the query and management of patients information 临床应用表明，所研制的自聚焦口腔内窥镜不仅操作简单、成像清晰且便于对患者的各种信息进行管理、查询，有望成为牙科医生必备的一种新诊疗设备。
The feasibility of the proposed method is verified by real data . presented is a solution of pga algorithm for stripmap sar autofocusing via data conversion . its validity is proved by the processing results of real data 在数据转换的基础上，给出一种pga用于条带模式sar图像自聚焦的方法，实测数据处理结果验证了该方法的有效性。
Then a compensation method directly extracting phase errors from raw data is discussed . this dissertation discusses a robust autofocus algorithm : phase gradient autofocus algorithm , and its application in stripmap mode sar 本文讨论了一种有较强鲁棒性的自聚焦算法：相位梯度自聚焦算法，并介绍了它在条带模式合成孔径雷达中的应用。
