Morphological analysis of active Mount Nemrut stratovolcano, eastern Turkey: evidences and possible impact areas of future eruption

Mount Nemrut, an active stratovolcano in eastern Turkey, is a great danger for its vicinity. The volcano possesses a summit caldera which cuts the volcano into two stages, i.e. pre- and post-caldera. Wisps of smoke and hot springs are to be found within the caldera. Although the last recorded volcanic activity is known to have been in 1441, we consider here that the last eruption of Nemrut occurred more recently, probably just before 1597. The present active tectonic regime, historical eruptions, occurrence of mantle-derived magmatic gases and the fumarole and hot spring activities on the caldera floor make Nemrut Volcano a real danger for its vicinity. According to the volcanological past of Nemrut, the styles of expected eruptions are well-focused on two types: (1) occurrence of water within the caldera leads to phreatomagmatic (highly energetic) eruptions, subsequently followed by lava extrusions, and (2) effusions–extrusions (non-explosive or weakly energetic eruptions) on the flanks from fissures. To predict the impact area of future eruptions, a series of morphological analyses based on field observations, Digital Elevation Model and satellite images were realized. Twenty-two valleys (main transport pathways) were classified according to their importance, and the physical parameters related to the valleys were determined. The slope values in each point of the flanks and the Heim parameters H/L were calculated. In the light of morphological analysis the possible impact areas around the volcano and danger zones were proposed. The possible transport pathways of the products of expected volcanic events are unified in three main directions: Bitlis, Guroymak, Tatvan and Ahlat cities, the about 135 000 inhabitants of which could be threatened by future eruptions of this poorly known and unsurveyed volcano.     

The role of sediment specific gravity and availability on cluster evolution

The objective of this experimental study was to account for the role of sediment availability and specific gravity on cluster formation and cluster geometric characteristics (spacing and size). To isolate the effects of sediment availability and specific gravity on cluster evolution, mono‐sized spheres were used to simulate the cluster evolutionary cycle. Overall, twelve experimental runs were carried out in the laboratory flume. Six of these tests were performed by using glass spheres (specific gravity, SG = 2·58) and the other six by employing an equal combination of glass and Teflon spheres (SG = 2·12) of the same diameter to evaluate the role of specific gravity on cluster evolution. The three sediment availability conditions that were investigated here simulated isolated gravel elements, pool–riffle sequences and densely packed gravel‐bed. An advanced image analysis technique was employed to track the evolution of cluster microforms and provide quantitative information about the size and shape of clusters and the number of clusters per unit area. The results of this study showed that: (1) sediment availability affects the architecture and size of cluster microforms; and (2) clusters consisting of mono‐sized sediments start disintegrating at twice the incipient conditions. By performing complementary tests for the isolated gravel elements case, it was found that the evolutionary cycle of individual clusters could be described as follows, in order of increasing stress: no cluster→two particle cluster→comet→triangle→rhomboid→break up. Copyright © 2003 John Wiley & Sons, Ltd.     

遗传算法与单纯形法组合的影像纹理分类方法

提出遗传算法(简称GA)与单纯形法组合的影像纹理分类方法(简称GASPX)。单纯形法是一种局部搜索方法，它通过反射，扩张，收缩操作，求得新的单纯形点，组成新单纯形，新单纯形比前一个单纯形更接近局部最优解。这种寻优方法收敛速度快，它与GA组合起来可以改善单独使用GA收敛速度慢的缺陷。由于在组合算法中是多个单纯形的局部区域的并行搜索，避免GA优化过程中过早收敛于局部最优解的现象出现。通过5种不同类别航空影像纹理识别的试验，并与GA的结果作对比，结果表明GASPX法优于GA法。     

影像匹配中几种相似性测度的分析

对基于灰度影像匹配中的几种相似性测度进行了研究，分析了每种测度的直观意义、限制条件以及改进措施，最后通过实验结果验证了上述结论。     

基于图像特征的烟叶分级

讨论了基于图像特征的烤烟烟叶分级系统的建模及其实现，给出了烟叶分级模型的数学描述，探讨了模型库的优化和特征隶属度及烟叶模式的可信度的计算问题，并通过试验分析了FTGS系统的性能和有效性。     

利用频谱解混叠方法实现超分辨率影像重建

基于信号处理的超分辨率影像重建技术，可以消除由影像系统引起的影像模糊和退化，同时恢复出光学权限外的频谱信息。首先简要介绍了超分辨率影像重建技术的意义和基本过程；并对影像配准与运动模型估计在超分辨率影像重建中的作用给予简要介绍；接着根据连续傅里叶变换(CFT)和离散傅里叶变换(DFT)的频谱混叠关系及CFT位移性质，推导出频谱解混叠的超分辨率影像重建模型；最后采用文献中的运动模型估计方法和本文的重建算法，对几组数据进行实验，获得了空间分辨率提高近1倍的影像。     

从激光扫描数据中进行建筑物特征提取研究

提出了一套基于建筑物几何特征的信息挖掘方案，并具体介绍了研究中采用的一些原理、方法与实用算法，从而可以直接从激光扫描数据中提取建筑物的平面外轮廓信息。利用本方案对车载激光扫描系统获取的城市建筑物试验数据进行了具体的处理，并给出了三维建模和可视化表达结果。     

从卫星遥感全色图像中自动提取城市目标

提出了一种从卫星遥感全色图像中自动提取城市目标的方法。在总结城市目标的卫星遥感全色图像特性的基础上 ,设计了一种层次提取的方法。首先在低分辨率图像中提取城市目标的候选区域 ;接着在候选区域内利用城市目标一些更复杂的特性在高分辨率图像中证实城市目标。为了获得城市目标的边界 ,提出了一种基于边缘点密度的算法 ,并将算法应用去提取SPOT图像中的城市目标 ,取得了较好的试验结果     

利用MATLAB实现图像处理与分析

本文通过对图像的均衡操作、二值图像的处理、小波去噪等实例，介绍了MATLAB进行图像处理和分析的实用方法与技巧，它对各种软钉包、进行图像处理和分析等，提供了高效便捷的方法。     

煤田火区烧变岩光谱特征分析及其信息提取

中国北方煤田煤层自燃现象非常严重.利用遥感手段可以快速实现火区的动态监测,及时为灭火工程提供信息.烧变岩作为火区的地表指示性特征,是火区解译最直观的信息.本文从烧变岩的反射光谱曲线特征入手,对几种提取烧变岩信息的方法进行比较,从而确定解译烧变岩的最佳方法,为圈定火区的范围和位置奠定基础.