IR Spectral Analysis of Diterpene Glycosides Isolated from <i>Stevia rebaudiana</i>

The objective is to identify the Infra-Red (IR) spectral analysis of the diterpene glycosides present in the commercial extracts of Stevia rebaudiana was achieved by PerkinElmer Spectrum 400 Fourier Transform (FT) spectrometer employing a PerkinElmer Universal Attenuated Total Reflection (ATR) accessory. Using this technique the IR spectral pattern of 15 steviol glycosides which belongs to three different classes of ent-kaurane diterpene glycosides namely ent-13-hydroxykaur-16-en-19-oic acid, ent-13-hydroxykaur-15-en-19-oic acid, and 13-methyl-16-oxo-17-norent- kauran-19-oic acid were identified. From the wave numbers found for all 15 steviol glycosides, it was observed that that though there are differences in the number of sugar units, nature of sugar units, and their attachments;there are not any notable differences in the IR values.

IR-MAD算法的遥感影像变化检测方法研究

变化检测技术是遥感图像处理的研究热点之一。针对目前多元变化检测方法不能有效地去除波段间相关性且检测结果对噪声敏感等问题,在深入研究迭代加权多元变化检测算法原理的基础上对黄河入海口区域的Landsat影像进行变化检测试验,选择了变化剧烈的黄河河道进行精度评价。其中迭代加权多元变化检测方法检测精度高达76.8%,直接相减法精度为50.5%,主成分分析法精度为13.2%,与这两种传统检测算法相比具有明显的提高。研究表明,IR-MAD算法能够有效地去除噪声和去相关,且检测精度高,同时也具有人工干预少、执行效率高等显著优点。

多源遥感影像的融合方法效果分析

在IRS-P6遥感影像的多光谱与CBERS-2B遥感影像的全色PAN波段之间进行融合,对乘积变换、比值变换、IHS变换和主成分分析4种常见的融合方法进行对比分析,并对融合后的影像进行主观定性评价和客观定量评价。研究表明:IHS变换效果相对最优,在较好地保持原多光谱影像光谱信息的同时,大大地提高了影像的空间分辨率,对云区的地物色彩表现力上也较好。研究对于使用多源遥感影像融合获取高质量影像有着重要的参考价值。