In this work six kinds of tartrate diesters were prepared from D(-), L(+) or DL-tartaric acid respectively, and their structure were verified by IR and NMR. The extraction behavior of optical compounds, D(-) ephedrine...In this work six kinds of tartrate diesters were prepared from D(-), L(+) or DL-tartaric acid respectively, and their structure were verified by IR and NMR. The extraction behavior of optical compounds, D(-) ephedrine and L(+) pseudoephedrine, was investigated at room temperature using prepared tartrate diester as extracting agent and n -heptane as diluent. The ratio of tartrate diester and n -heptane is 1∶1. Distribution coefficients, obtained from experiment data by material balance, show that there is a chiral recognition: L(+) tartrate diesters favour extraction of L(+) pseudoephedrine,while D(-) tartrate diesters favour extraction of D(-) ephedrine. The extraction behavior of the mixture of the above optical active epimerides, was also investigated under the same experimental conditions. The experiment data with HPLC also showed the same conclusion. Meanwhile, a blank experiment was carried out and the result showed that there was no evident effect on extraction distribution coefficients when extraction process occurred in the presence of n -heptane. The relationship between the structure of extracting agent and optical activity of the epimerides was also discussed.展开更多
高精度雷达散射截面(RCS)测量对背景环境具有较高要求,当背景环境存在较强干扰时,通过背景矢量对消难以消除杂波影响。提出基于成像提取的高精度RCS测量方法,从背景杂波中分离和提取出目标的散射信号,从而提高了测量的精度。首先推导了...高精度雷达散射截面(RCS)测量对背景环境具有较高要求,当背景环境存在较强干扰时,通过背景矢量对消难以消除杂波影响。提出基于成像提取的高精度RCS测量方法,从背景杂波中分离和提取出目标的散射信号,从而提高了测量的精度。首先推导了像与RCS的数学关系,然后利用转台模式下的测量回波进行成像处理,得到目标区域的二维像;从成像区域中提取目标的二维像,通过波谱变换和定标获得目标的RCS。仿真结果表明,该方法对于具有干扰情况下的RCS测量,可以改善3~5 d B的测试精度,并且能够对弱散射目标进行测量。实验结果表明了成像提取方法的有效性和准确性。展开更多
针对空间异质性导致的道路几何纹理特征突出性下降问题,提出一种高分辨率遥感影像道路提取方法.首先设定跟踪模型,依据人工输入点,自适应提取道路中心点和道路宽度,设计迭代内插、双向迭代两种跟踪方式以及矩形跟踪模板;然后提出多描述...针对空间异质性导致的道路几何纹理特征突出性下降问题,提出一种高分辨率遥感影像道路提取方法.首先设定跟踪模型,依据人工输入点,自适应提取道路中心点和道路宽度,设计迭代内插、双向迭代两种跟踪方式以及矩形跟踪模板;然后提出多描述子道路匹配模型,针对道路几何纹理特征突出性不足问题,基于道路区域地物边缘与道路方向一致的语义关系,通过线段峰值约束的思想,提出一种多尺度线段方向直方图(Multi-scale line segment orientation histogram,MSLSOH)描述子,以此对跟踪方向进行预测;针对道路几何纹理特征均质性下降问题,从道路区域与道路非道路混合区域纹理差异性出发,组合三角形构成扇形描述子,突出道路影像纹理特征,以此不仅可对预测跟踪点进行验证,而且也可在结构信息缺失的情况下对道路进行跟踪;最后选取不同类型、不同分辨率、不同场景的高分辨率遥感影像,通过与其他方法的实验对比,表明该方法能够解决道路提取过程中几何纹理特征突出性下降问题,具有准确率高和自动化程度高的优势.展开更多
Road extraction plays an important role in many applications such as car navigation, but the manual extraction of roads is a laborious, tedious task. To speed the extraction of roads, an approach based on particle fil...Road extraction plays an important role in many applications such as car navigation, but the manual extraction of roads is a laborious, tedious task. To speed the extraction of roads, an approach based on particle filtering to extract automatically roads from high resolution imagery is proposed. Particle filtering provides a statistical framework for propagating sample-based approximations of posterior distributions and has almost no restriction on the ingredients of the model. We integrate the similarity of grey value and the edge point distribution of roads into particle filtering to deal with complex scenes. To handle road appearance changes the tracking algorithm is allowed to update the road model during temporally stable image observations. A fully automatic initialization strategy is used. Experimental results show that the proposed approach is a promising and fully automatic method for extracting roads from images, even in the presence of occlusions.展开更多
文摘In this work six kinds of tartrate diesters were prepared from D(-), L(+) or DL-tartaric acid respectively, and their structure were verified by IR and NMR. The extraction behavior of optical compounds, D(-) ephedrine and L(+) pseudoephedrine, was investigated at room temperature using prepared tartrate diester as extracting agent and n -heptane as diluent. The ratio of tartrate diester and n -heptane is 1∶1. Distribution coefficients, obtained from experiment data by material balance, show that there is a chiral recognition: L(+) tartrate diesters favour extraction of L(+) pseudoephedrine,while D(-) tartrate diesters favour extraction of D(-) ephedrine. The extraction behavior of the mixture of the above optical active epimerides, was also investigated under the same experimental conditions. The experiment data with HPLC also showed the same conclusion. Meanwhile, a blank experiment was carried out and the result showed that there was no evident effect on extraction distribution coefficients when extraction process occurred in the presence of n -heptane. The relationship between the structure of extracting agent and optical activity of the epimerides was also discussed.
文摘高精度雷达散射截面(RCS)测量对背景环境具有较高要求,当背景环境存在较强干扰时,通过背景矢量对消难以消除杂波影响。提出基于成像提取的高精度RCS测量方法,从背景杂波中分离和提取出目标的散射信号,从而提高了测量的精度。首先推导了像与RCS的数学关系,然后利用转台模式下的测量回波进行成像处理,得到目标区域的二维像;从成像区域中提取目标的二维像,通过波谱变换和定标获得目标的RCS。仿真结果表明,该方法对于具有干扰情况下的RCS测量,可以改善3~5 d B的测试精度,并且能够对弱散射目标进行测量。实验结果表明了成像提取方法的有效性和准确性。
文摘针对空间异质性导致的道路几何纹理特征突出性下降问题,提出一种高分辨率遥感影像道路提取方法.首先设定跟踪模型,依据人工输入点,自适应提取道路中心点和道路宽度,设计迭代内插、双向迭代两种跟踪方式以及矩形跟踪模板;然后提出多描述子道路匹配模型,针对道路几何纹理特征突出性不足问题,基于道路区域地物边缘与道路方向一致的语义关系,通过线段峰值约束的思想,提出一种多尺度线段方向直方图(Multi-scale line segment orientation histogram,MSLSOH)描述子,以此对跟踪方向进行预测;针对道路几何纹理特征均质性下降问题,从道路区域与道路非道路混合区域纹理差异性出发,组合三角形构成扇形描述子,突出道路影像纹理特征,以此不仅可对预测跟踪点进行验证,而且也可在结构信息缺失的情况下对道路进行跟踪;最后选取不同类型、不同分辨率、不同场景的高分辨率遥感影像,通过与其他方法的实验对比,表明该方法能够解决道路提取过程中几何纹理特征突出性下降问题,具有准确率高和自动化程度高的优势.
文摘Road extraction plays an important role in many applications such as car navigation, but the manual extraction of roads is a laborious, tedious task. To speed the extraction of roads, an approach based on particle filtering to extract automatically roads from high resolution imagery is proposed. Particle filtering provides a statistical framework for propagating sample-based approximations of posterior distributions and has almost no restriction on the ingredients of the model. We integrate the similarity of grey value and the edge point distribution of roads into particle filtering to deal with complex scenes. To handle road appearance changes the tracking algorithm is allowed to update the road model during temporally stable image observations. A fully automatic initialization strategy is used. Experimental results show that the proposed approach is a promising and fully automatic method for extracting roads from images, even in the presence of occlusions.
