Comparison of Landsat OLI,ASTER, and Sentinel 2A data in lithological mapping : A Case study of Rich area (Central High Atlas,Morocco)

The eastern part of the Rich area consists of the massive Paleozoic and Meso-Cenozoic cover formations that present the geodynamic development of the study area, where is characterized by various carbonate facies of Jurassic age. The geographical characteristic of the study area leaves the zone difficult to map by conventional methods. The objective of this work focuses on the mapping of the constituent lithological units of the study area using multispectral data of Landsat OLI, ASTER, and Sentinel 2A MSI. The processing of these data is based on a precise methodology that distinguishs and highlights the limits of the different lithological units that have an approximate similarity of spectral signature. Three techniques were used to enhance the image including Principal Component Analysis (PCA), Minimum Noise Fraction (MNF), and Independent Component Analysis (ICA). Lithological mapping was performed using two types of supervised classification : Maximum likelihood classifier (MLC) and Support Vector Machine (SVM).The results of processing data show the effectiveness of Sentinel 2A data in mapping of lithological units than the ASTER and Landsat OLI data. The classification evaluation of two methods of the Sentinel 2A MSI image showed that the SVM method give a better classification with an overall accuracy of 93,93% and a Kappa coefficient of 0.93, while the MLC method present an overall accuracy of 82,86% and a Kappa coefficient of 0.80. The results of mapping obtained show a good correlation with the geological map of the study area as well as the efficiency of remote sensing in identification of different lithological units in the Central High Atlas.     

可数非扩张映像族公共不动点迭代算法

提出一种计算可数个非扩张映像族公共不动点的新的迭代算法，并证明了算法的强收敛性。本算法由于避免使用形一映像，因而使得算法简洁，计算工作量较小。     

Glacier mapping based on rough set theory in the Manas River watershed

Precise glacier information is important for assessing climate change in remote mountain areas. To obtain more accurate glacier mapping, rough set theory, which can deal with vague and uncertainty information, was introduced to obtain optimal knowledge rules for glacier mapping. Optical images, thermal infrared band data, texture information and morphometric parameters were combined to build a decision table used in our proposed rough set theory method. After discretizing the real value attributes, decision rules were calculated through the decision rule generation algorithm for glacier mapping. A decision classifier based on the generated rules classified the multispectral image into glacier and non-glacier areas. The result of maximum likelihood classification (MLC) was used to compare with the result of the classification based on the rough set theory. Confusion matrix and visual interpretation were used to evaluate the overall accuracy of the results of the two methods. The accuracies of the rough set method and maximum likelihood classification were compared, yielding overall accuracies of 94.15% and 93.88%, respectively. It showed the area difference based on rough set was smaller by comparing the glacier areas of the rough set method and MLC with visual interpreter, respectively. The high accuracy for glacier mapping and the small area difference for glacier based on rough set theory demonstrated that this method was effective and promising for glacier mapping.     

测绘装备野外计量保障系统的设计与实现

在野外条件下,测绘装备的伴随保障对于保证测绘装备技术性能、提升装备的保障能力,随时遂行各种测绘任务至关重要。本文系统地介绍了测绘装备野外计量保障系统的设计目的、原则和依据;车载式长度、角度、频率检定标准装置的组成和建立方法,野外维修保障设备的配备、计量保障方舱的重心偏移量。分析了野外条件下长度、角度标准的测量不确定度,证明了测绘装备野外计量保障系统完全可以满足检定和维修大地测量装备的要求。     

模H-Nielsen数(2)

通过研究自映射ｆ在π１（Ｘ，ｘ０）上的作用ｆπ，发现只要适当地选取π１（Ｘ，ｘ０）中子群Ｈ（ｆπ，π１）作为正则复迭空间的子群，得到模Ｈ－Ｎｉｅｌｓｅｎ数等于Ｎｉｅｌｓｅｎ数的结果，从而简化了用模Ｈ－Ｎｉｅｌｓｅｎ数计算Ｎｉｅｌｓｅｎ数的过程。     

传输型立体测绘相机几何精度仿真分析

航天传输型立体测绘相机几何精度和稳定性决定了立体摄影成像的精度,对其几何精度测试技术需作专门研究。文章介绍了传输型立体测绘相机几何精度测试方法,推导了基于最小二乘原理进行几何精度测试的主点、主距和畸变误差传递公式,对主点、主距和畸变测试精度进行了全面的仿真分析,仿真结果可以为测绘相机设计和测试人员提供参考。     

三维工序模型的演进式构建方法

为实现以三维工序模型为核心的三维工艺构建,基于从毛坯模型到最终产品模型的演进过程,对三维工序模型的生成方法进行研究.在制造特征信息模型的基础上,结合基准信息建立了面向工序模型生成的工序信息模型.提出制造特征信息在工序模型中的映射机制,解决该模式下工序模型信息缺失的问题.以工序信息模型为模板,首先定义加工特征基元,然后通过实例化实现工序模型的变换.最后,通过集成工艺决策系统,构建三维工序模型生成系统,为后续工艺尺寸标注和工艺展示提供模型支持.     

代数基本定理的拓扑证明

使用同调群和映射度等工具，给出代数基本定理的两种拓扑证明。     

不可压缩势流绕多段翼型流动的快速迭代解法

利用保角变换计算不可压缩势流绕翼型的流动,具有计算速度快和要求计算机内存小的优点,但主要用于单段翼型问题,而对于多段翼型,尤其是三段和三段以上的翼型则很难应用。本文在单段翼型的保角变换的基础上,提出了一种利用迭代算法计算任意多段翼型的不可压缩势流的绕流问题的方法。本文方法和目前常用的边界元法相比,具有计算速度快的优点。本方法还可进一步推广到考虑无粘流/边界层的迭代计算中。     

收缩段出口型式对水槽流场品质的影响

研究了收缩段出口顶壁型式对表面波的影响，得到了最佳的出口设计，并分析了满流和明流情况下，流场速度，湍流等澡程的发展变化。