基于极化SAR图像分类的海上舰船检测

本文针对极化熵类检测方法的不足,在极化特征分解以及Touzi等人工作的基础上,提出了能够更全面的表征舰船和杂波差别的特征矢量,并提出了一种基于特征矢量的非监督分类方法。使用该方法进行海上舰船的检测,不仅取得了很好的舰船和海面的分离效果,而且也得到了较好的舰船与其他人造目标的区分效果。实测数据的检测结果证明该分类方法具有很好的收敛性,是一种有效的舰船检测方法。     

Multi-sensors SAR system for real-time dosimetry assessment

A multi-sensor test-bench for determining the SAR (specific absorption rate) due to wireless devices emitting in equivalent human tissues is presented. Real-time SAR assessment is proposed considering a spatially distributed multiprobe test-bench. In comparison with a multi-axial robot SAR system, the proposed one does not require any displacement, thus reducing drastically acquisition time, once parallel data acquisition and interpolation techniques are employed for accelerating measurements.     

Clutter suppression method for heterogeneous environment

Clutter suppression is a key process in ground moving target indication (GMTI). Adaptive filtering is an effective method for clutter suppression but the performance degrades severely in heterogeneous clutter environment. To solve this problem, a new clutter suppression method is proposed. The approach uses subspace tracking technique to update clutter subspace of different clutter patches which may mitigating the heterogeneous effects. Simulation results illustrate that the method performs well when lacking of the independent and identically distributed (i.i.d.) samples.     

国外天基雷达的发展趋势

天基雷达工作在较高的高度,能够不受日照和天气条件的限制,全天候、全天时的对地、对空进行探测,具有可见光和红外遥感系统不可比拟的优点.文中介绍了国外天基雷达的发展水平,以及天基雷达在功能和平台上的多样性,分析了天基雷达系统及其未来发展趋势.     

机载SAR稳定平台坐标变换及其软件实现

介绍了机载SAR雷达成像对天线指向的要求和稳定平台的系统组成，详细推导了坐标正变换和坐标反变换算法，给出了单片机汇编语言软件框图，经过仿真计算证明其精度可以达到成像要求。     

合成孔径雷达光学处理器的检测方法

本文以一个通用合成孔径雷达光学处理器(简称OSARP)的检测为例,来说明OSARP的检测方法。给出OSARP的每个可调部件与合成孔径雷达(简称SAR)数据片的各特征参数间的关系,通过测量调整量求得OSARP的适用范围;用普通检测目标加位移透镜,来检测OSARP的成像质量。同时用模拟的SAR数据片,以另一种方法对OSARP做检测,结果相同。最后处理了真实SAR数据片,用来展示SAR和OSARP的综合成像质量。文中给出一些实验照片和数据,结果表明,本检测方法是可行的。     

Antibacterial activity of N-quaternary chitosan derivatives: Synthesis, characterization and structure activity relationship (SAR) investigations

Quaternary N-(2-(N,N,N-tri-alkyl ammoniumyl and 2-pyridiniumyl) acetyl) derivatives of chitosan polymer, chitooligomer, and glucosamine (monomer) were synthesized for the purpose of investigating the structure activity relationship (SAR) for the antibacterial effect. Novel methods were used in the synthesis. The final chitosan and chitooligomer derivatives could thus be obtained in two steps without prior protection of the hydroxyl groups. However, in order to obtain chitosan derivatives with the bulky N,N-dimethyl-N-dodecyl- and N,N-dimethyl-N-butyl side chains three steps were needed, starting from 3,6-O-di-tert-butyldimethylsilyl chitosan (3,6-O-di-TBDMS chitosan) as the key intermediate. The quaternary ammoniumyl acetyl derivatives of glucosamine were synthesized from glucosamine or tetra-O-acetylglucosamine. N,N,N-trimethyl chitosan (TMC) was used as reference compound for investigation of antibacterial activity. Clinical Laboratory Standard Institute (CLSI) protocols were used to determine MIC and MLC for activity against clinically important Gram-positive strains Staphylococcus aureus (ATCC 25923), and S. aureus (MRSA) (ATCC 43300), and Gram-negative strains of Escherichia coli (ATCC 25922), P. aeriginosa (ATCC 27853) and Enterococcus facialis (ATCC 29212). The MIC values for the compounds ranged from 8 to ?8192 mg/L. In general the N-(2-(N,N-dimethyl-N-dodecyl ammoniumyl) acetyl) derivatives of chitooligomer and glucosamine monomer were more active against bacteria than derivatives with shorter alkyl chains. In contrast the N-(2-(N,N-dimethyl-N-dodecyl ammoniumyl) acetyl) derivatives of chitosan were less active than derivatives with N-(2-N,N,N-trimetylammoniumyl) acetyl or N-(2-(N-pyridiniumyl) acetyl) quaternary moiety. N,N,N-trimethyl chitosan (TMC) was the most active compound in this study.     

相干斑对SAR图像纹理计算的影响

根据相干斑模型,构造相干斑,利用小波变换和灰度共生矩阵对加噪前后的图像分析和对比,通过对得到的实验数据和图形进行深入的分析,探讨相干斑对SAR图像纹理计算的影响。