基于区域的MRF模型用于SAR图像分割

本文提出了一种建立在流域算法过分割结果区域图上的马尔可夫随机场模型的SAR图像分割算法.由于将马尔可夫场随机场(MRF)模型建立在预分割的基础上,极大减少了计算复杂度,并利用SAR图像的分布模型建立多层MRF模型,采用模拟退火优化得到MAP估计的分割结果.实验证明较传统的基于像素的马尔可夫随机场分割算法,该方法极大提高了运算速度,并能取得较为满意的分割结果.     

On the Extension of Multidimensional Speckle Noise Model From Single-Look to Multilook SAR Imagery

Speckle noise represents one of the major problems when synthetic aperture radar (SAR) data are considered. Despite the fact that speckle is caused by the scattering process itself, it must be considered as a noise source due to the complexity of the scattering process. The presence of speckle makes data interpretation difficult, but it also affects the quantitative retrieval of physical parameters. In the case of one-dimensional SAR systems, speckle is completely determined by a multiplicative noise component. Nevertheless, for multidimensional SAR systems, speckle results from the combination of multiplicative and additive noise components. This model has been first developed for single-look data. The objective of this paper is to extend the single-look data model to define a multilook multidimensional speckle noise model. The asymptotic analysis of this extension, for a large number of averaged samples, is also considered to assess the model properties. Details and validation of the multilook multidimensional speckle noise model are provided both theoretically and by means of experimental SAR data acquired by the experimental synthetic aperture radar system, operated by the German Aerospace Center     

基于Otsu和改进CV模型的SAR图像水域分割算法

图像分割是SAR图像处理中基本而关键的技术之一,也是影响SAR图像自动解译性能的一个重要步骤。由于受相干斑噪声影响严重,SAR图像分割一直是一个公认的难题。针对Otsu算法对SAR图像分割精度不高以及CV模型对初始条件敏感和演化效率低等问题,本文提出了一种融合分割算法。采用快速一维Otsu算法对图像进行粗分割,分别将得到的水体区域和水体轮廓作为CV模型的分割区域和初始条件,降低了CV模型的场景复杂度,提高了分割速度,减弱了CV模型对初始条件的敏感性。利用图像边缘强度信息代替CV模型中的Dirac项,改进了CV模型的偏微分方程,使分割算法更好地适应SAR图像的同时提高了CV模型的收敛速度。实验结果表明,融合分割算法具有分割边界定位准确、运行高效、无需设置初始条件等优点。      

一种用于星载SAR天线的转动控制技术

针对星载合成孔径雷达（SAR）天线要求在超低转速下平稳转动,同时满足小型化轻量化的要求,本文提出一种基于微步距模式的天线转动控制技术,该技术使用两个带PWM电路的全桥驱动器通过微步距方式驱动步进电机。在给出系统架构、微步距控制原理后,进一步提出可靠性设计的具体措施。经测试和环境试验验证,该技术对同类应用具有一定的参考价值。     

基于统计特征的GAC模型SAR图像分割

提出了一种基于统计特征定义边缘检测算子的测地活动轮廓（GAC）模型,并用于SAR图像分割中。首先,根据图像上每个点四个不同方向邻域统计特征的异同,计算边缘检测算子,得到GAC模型的能量泛函。其次,最小化能量泛函,得到曲线演化偏微分方程,水平集方法数值求解,最终完成SAR图像的分割。实验表明,与传统依赖图像梯度定义检测算子的GAC方法相比,文中的方法完全适用于SAR图像分割,不需要噪声的预处理过程,拓展了GAC模型的应用范围,提高了目标的正确识别率。     

Edge-based Segmentation Using Robust Evolutionary Algorithm Applied to Medical Images

Although medical image segmentation is a hard task in image processing, it is possible to reduce its complexity by considering it as an optimization problem. This paper presents a robust evolutionary algorithm based on a cost minimization function to segment and to extract image edges. Since, the goal is to outperform a high edge detection quasi independent from the input problem characteristics, an adaptive detector is considered. As a first step, the main evolutionary algorithm parameters are highlighted based on an adaptive parameterization to overcome convergence problem. In a second stage, the reached optimal setting is applied on medical images to exhibit the quality of the proposed algorithm.     

脉冲卷积干扰技术在超宽带SAR中的应用分析

为探讨脉冲卷积干扰技术在超宽带SAR中应用的可行性,详细分析了距离像和二维像的干扰效果,发现在二维图像中,方位向的聚焦性能明显下降。通过对目标回波和干扰信号处理流程的分析,发现超宽带SAR空变特性是导致二维图像散焦的根本原因。提出对干扰信号进行相位调制,调整干扰信号的分布曲线,以降低空变特性的影响,取得了较好的干扰效果。研究表明,距离向的干扰效果与常规雷达一致,可以形成滞后的假目标欺骗干扰,改进的脉冲卷积干扰大大提高了方位向聚焦性能,用于对超宽带SAR进行假目标干扰。仿真结果验证了理论分析的正确性。     

用合成孔径雷达(SAR)对地面动目标(GMTI)成像

综述两种SAR/GMTI方法。一种是多端口SAR/GMTI,以四端口天线SAR/GMTI作为实例,例如APY-6的基本功能以及它的试飞结果;另一种方式是空时自适应处理(STAP)。叙述了二通道STAP处理SAR/GMTI的试飞结果和成像情况。     

Limitations of the Cubical Block Model of Man in Calculating SAR Distributions (Comments)

The above paper raised some serious questions regarding the accuracy of three-dimensional block model solutions obtained using a pulse-function basis. While I am in qualitative agreement with about half of the numerical results presented in the paper, I most strongly disagree with most of the interpretations which the authors have made using those results. It is my belief that it is possible to obtain high accuracy with block model solutions if sufficient care is used in their implementation. I have chosen to use a pulse-function basis with block models of man since this appears to allow the model to have much greater detail than is possible with more elaborate bases.     

CAF：电子工业小型化的威胁

概述了CAF的历史、发生的原理,分析了CAF产生的根本原因,比较了几种CAF失效分析的方法,同时也介绍了一种简易的测试设备。     

SAR动目标欺骗干扰模型分析

欺骗式干扰是对合成孔径雷达的一种有效的干扰方式。在分析运动点目标的合成孔径雷达回波特性基础上,得出了利用干扰机生成虚假动目标的方法。分析了SAR静止目标成像系统对动目标的成像效果,提出并解决了基于场景环境的运动参数设置问题。最后利用实验仿真验证了方法的正确性。     

Region Segmentation in the Frequency Domain Applied to Upper Airway Real-Time Magnetic Resonance Images

We describe a method for unsupervised region segmentation of an image using its spatial frequency domain representation. The algorithm was designed to process large sequences of real-time magnetic resonance (MR) images containing the 2-D midsagittal view of a human vocal tract airway. The segmentation algorithm uses an anatomically informed object model, whose fit to the observed image data is hierarchically optimized using a gradient descent procedure. The goal of the algorithm is to automatically extract the time-varying vocal tract outline and the position of the articulators to facilitate the study of the shaping of the vocal tract during speech production.      

一种适用于rural区SAR图像目标感兴趣区域获取方法

目标感兴趣区域的获取是目标分类的基础,由大场景图像中快速获取目标感兴趣区域对整个ATR系统的性能提高有较大意义。本文给出了一种适用于rural区的SAR图像目标感兴趣区域获取方法,在分析图像场景灰度统计分布的基础上,利用全局恒虚警率检测算法得到潜在目标区域,然后利用密度、形态学和尺寸滤波器对潜在目标区域聚类并滤除虚警,最终获得目标感兴趣区域。对2048×512像素实际场景的实验结果,应用本文算法4个车辆目标全部被检测且没有虚警,VC代码获取目标区域的总时间小于0.5秒。     

General Failure Model Applied to Preventive Maintenance Policies

The reliability behavior of systems is investigated if two types of failures can happen. Type 1 is removed by minimal repair, Type 2 by replacement. Reliability expressions are derived. The results are used for calculating the s-expected long-run cost rate for a generalized age replacement policy and repair limits.     

Matching map features to synthetic aperture radar (SAR) imagesusing template matching

The feasibility of matching templates representing map features to features in synthetic aperture radar images is investigated. The performance of template matching using cross-correlation (which has no knowledge of speckle) is compared with a correlation measure, based on a Kolmogorov-Smirnov test of fit, which does take speckle into consideration. This is shown to perform better than cross-correlation in simulated images. However, neither method performs well on real data. This is due to the exponential speckle model being inappropriate for linear features in real data. Alternative methods for matching map features to SAR images are suggested     

偏振保持光纤的研制(熊猫型)

本文重点介绍熊猫型双折射偏振保持光纤的制作工艺、结构和性能参数。     

适用于宽带通信系统的 DHW功放模型

为有效模拟宽带通信系统中功放的非线性行为,研究了一种双路 Hammerstein-Wiener（DHW）功放模型。分别施加相同的激励信号于该模型的Hammerstein分支和Wiener分支,并将两分支输出信号累加作为最终的响应。利用NXP功放管进行Doherty电路设计并加入多载波WCDMA信号驱动,从ADS中导出强非线性输入输出数据进行模型实验测试。结果显示阶数相同条件下,与 Hammerstein和Wiener模型相比,此双路 Hammerstein －Wiener功放模型能够获得更好的RMSE 。另外,该功放模型可在减少整个记忆多项式参数数量30％～40％的前提下,获得与记忆多项式模型近似相同的性能,对功放系统行为模型的研究具有重要的参考价值。     

Characterization and Electrochemical Mechanism for Bromide-Containing Conductive Anodic Filament (CAF) Failure

Conductive anodic filament (CAF) is a failure mode in printed wiring boards (PWBs) that occurs under temperature–humidity–bias (T–H–B) conditions. The filament, which is copper containing, grows subsurface from the anode to the cathode along the epoxy–glass fiber interface. In this study, hole-to-hole test coupons were processed using two thermal excursions for a high-bromide-containing (~15 wt.%) hot air soldering leveling (HASL) fluid. The coupons were then exposed to accelerated temperature, humidity, and bias conditions of 85°C, 85% relative humidity (RH), and 200 V bias, respectively, for 28 days. The aged coupons were then cross-sectioned, and scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) revealed that, in addition to bromide CAF, a copper-bromide-containing compound was present in the polymer matrix. The bromide-containing CAF was characterized using transmission electron microscopy (TEM) to be Cu₂(OH)₃Br. In addition, the copper-containing compound formed in the polymer matrix was characterized using x-ray photoelectron spectroscopy (XPS) to be CuBr. An electrochemical mechanism for the formation of bromide-containing CAF has been proposed based on the XPS data. It has been shown using Fourier-transform infrared (FTIR) spectroscopy that the polyol constituent from the flux diffuses into the board during soldering. Ion chromatography was used to show that bromide ions from the flux also diffuse into the board material during soldering.     

The J3 SCR Model Applied to Resonant Converter Simulation

The J3 SCR model is a continuous topology computer model for the SCR. Its circuit analog and parameter estimation procedure are uniformly applicable to popular computer-aided design and analysis programs such as SPICE2 and SCEPTRE. The circuit analog is based on the intrinsic three pn junction structure of the SCR. The parameter estimation procedure requires only manufacturer's specification sheet quantities as a data base.