回波图像

SAR image autofocus algorithm based on SAR echo is mainly studied in this dissertation.

本文重点讨论了基于SAR回波数据的SAR图像自聚焦算法。

This paper makes an analysis of the Doppler speed charts of clear weather and the echoes of large-area precipitation. It also singles out the Doppler speed charts of typical wind fields. In addition, this paper analyzes Doppler radars detecting process of the strong convection current weather system. It also conducts a thorough analysis of Doppler echo features of some hazardous weather, such as cell storm and downward storms. Based on this research and analysis, the paper reaches some important conclusions concerning the detecting methods using Doppler radar and the analysis of the information gathered by Doppler radar.

本文通过分析晴空和大面积降水回波的多普勒速度图像，归纳总结出了典型风场的多普勒速度图象，并着重分析了多普勒雷达对严重危害飞行安全的强对流天气系统的探测，特别是深入分析了超级单体风暴、下击暴流等灾害性天气的多普勒回波特征，得出了多普勒雷达对灾害性天气进行探测的方法、雷达资料分析应用等方面许多有益的结论。

In this dissertation, based on the extraction of meaningful polarization information, the polarimetric speckle reduction, polarimetric contrast enhancement, polarimetric classification and ship detection in polarimetric SAR images are systemically studied. During the study, some new concepts and methods are introduced, which are supported by the application to measured Pol-SAR data. The innovations of this dissertation are as follows: 1 A simplified schem is proposed to reduce the complexity of scattering-model-based speckle filtering. 2 Extend the expression of polarimetric correlation coefficient to help distinguishing targets. In addition, introduce the quantized parameters of polarimetric signature so as to show the differentiae in quantity in co-polar power, cross-polar power and shapes of polarization signatures among targets. 3 Define a new parameter of difference degree between targets, which can be used for express the difference between both coherent and distributed scatters.

论文在较系统的研究目标特征量提取方法和特征量所包含的物理意义的基础上，对极化SAR图像降斑、极化对比增强、极化SAR图像分类以及极化SAR图像中海上舰船目标检测等方面进行了研究，并提出了一些新的概念和方法，对实测数据的处理结果表明，这些新的概念和方法对于极化SAR信息处理是有效的，本文的主要创新成果包括以下方面： 1）针对基于预分类的MMSE极化降斑方法实现过程非常复杂的问题，提出了简化方案，并验证了方案的有效性； 2）扩展了极化相关系数的表示方法，这种扩展增强了极化相关系数对目标的区分效果；另外还提出了极化特征图量化参数，可以从量上表征不同目标间相同极化和交叉极化的回波功率差异和极化特征图形状差异； 3）定义了目标间的差异度参数，它不仅可以用于描述相干目标，还可以用于描述分布目标的差别程度。

By using the generalized central limit theorem, the heavy-tailed distributions (heavy-tailed Rayleigh distribution for amplitude image and heavy-tailed exponential distribution for intensity image) are obtained from the symmetric stable distributions of real and imaginary parts of echoes. Taking the heavy-tailed Rayleigh distribution as an example, the algebraic tails of heavy-tailed distributions are explained as well as the statistics of sharp peak and heavy tail.

本文使用广义中心极限定理，由雷达回波的实部和虚部的对称稳定分布，得到SAR图像的拖尾分布（幅值图像的拖尾Rayleigh分布以及强度图像的拖尾指数分布），并以拖尾Rayleigh分布为例，讨论了拖尾分布的代数拖尾特征以及尖峰厚尾的统计特性。

Result:The MR hydrography of inner ear of the patient displayed that there was an extradural high-signal intumescence which was like sliver shape and the edge of it was smooth and neat between the sigmoid sinus of the posterior cranial fossa and the inner acoustic meatus.

应用三维高级快速自旋回波序列横断扫描大前庭水管综合征患者的整个颞骨岩部，将所有原始图像传给网上工作站，应用最大密度投影法将图像进行三维重建，获内耳立体像。

The paper realizes the echo image and the interaction interface non-twinkle display by off-screen drawing , the echo image all-round sweep dynamic display and the simulation of functions of the sonar simulator.

通过离屏绘制实现了回波图像及人机交互界面的无闪烁显示，并实现了回波图像的圆周扫描动态显示和渔用声纳模拟器各种功能的模拟。

In display parts of the above-mentioned system, one key technology of the digital of radar video image has been solved. After A/D conversion and clutter suppression pretreatment, the radar analog data can be converted from polar coordinates to orthogonal coordinates and displayed in real time. Further, the image can achieve higher resolution and display speed in host.

本文所述显示系统中，结合实际需要，解决了该系统中雷达图像数字化的一种关键技术，将雷达模拟回波数据经A/D变换和杂波抑制预处理后，从极坐标到直角坐标实时地转换，并在计算机的光栅扫描显示器中显示，能够获得分辨率较高、实时性较好的雷达图像。

Methods Formalin-fixed rat and cat brains was examined on a 3.0 Tesla MR scanner with a quadrature wrist joint coil using single shot echo planar diffusion tensor imaging. Observing how to place brain tissue could decrease geometry deformation of DTI comparing T2WI.

方法运用3T磁共振扫描仪和正交腕关节线圈，采用单次激发回波平面扩散张量成像序列扫描猫、大鼠脑标本，观察何种放置方法获得的DTI图像相对于常规T2加权图像有最小的几何变形。

Application program manifests that the model simulates correctly the sonar's principle of sound reflection wave and sound shadow. The application is useful in theory research and simulation training especially.

软件实现结果表明，所给方法能正确仿真高频图像声纳的工作原理，准确表现声纳回波和声影图像，在理论研究、尤其是模拟训练领域具有重要应用价值。

Purpose:To determine the normal ranges of the depth of the anterior and posterior rims of foramen occipital magnum and the angle between medulla oblongata and the upper spinal cord on midsagittal MRI in normal Chinese idividuals and patients with basilar impression,to study their clinical significance and to provide normal reference in diagnosing basilar invagination by MRI.

目的：利用颅脑正中矢状面MRI自旋回波或快速自旋回波T_1WI图像测量颅颈交界区正常的中国人和颅底凹陷症患者枕大孔前、后缘中点深度和延髓-上颈髓轴线夹角数值，评价其正常值范围，探讨其发育规律及临床意义，为MRI诊断颅底凹陷症提供直接的参考标准。

It has been put forward that there exists single Ball point and double Ball points on the symmetrical connecting-rod curves of equilateral mechanisms.

从鲍尔点的形成原理出发，分析对称连杆曲线上鲍尔点的产生条件，提出等边机构的对称连杆曲线上有单鲍尔点和双鲍尔点。

The factory affiliated to the Group primarily manufactures multiple-purpose pincers, baking kits, knives, scissors, kitchenware, gardening tools and beauty care kits as well as other hardware tools, the annual production value of which reaches US$ 30 million dollars.

集团所属工厂主要生产多用钳、烤具、刀具、剪刀、厨具、花园工具、美容套等五金产品，年生产总值3000万美元，产品价廉物美、选料上乘、质量保证，深受国内外客户的青睐