Distribution and Variation of Glacier Velocity in Himalayas based on ALOS PALSAR

Based on the 12 scenes ALOS PALSAR data from December 2007 to February 2010,combined with SRTM,we estimated the glacier velocityof the Himalayasin three periods by feature tracking method.The results show that glacier velocity of the winter of 2007,the summer of 2009 and the winter of 2009 were between 0~300 m·a^-1,and accumulation area of the glacier have obvious movement only in summer,butthe movement of the glacier tongue is obviousin any season.Long tongue glacier velocity decreasesslowlyalong the mainstream line,while the short tongue glacier velocity fluctuatesalong the mainstream line,and even increases.The glacier in east aspecthas the largest velocity.The glaciervelocity in southeast aspect and the southwest aspect are second,and glacier velocity is minimum in the north aspect.In addition to climatic factors,it also closely relates to terrain factors.In terms of the slope of the four aspects,the north aspecthas the smallest slope,andit is one of the main causes of the smallest glacier velocity in the north aspect.There is an inter-annual variation of glaciers,that is,mean velocity of glaciers increases in winter,and the increased velocities are between -5~18 m·(2a).The glacier with small areavaries greatly,and the glacier with large area varies little.Meanwhile,the glacier velocity also has seasonal variation.The overall velocity in summer is larger than that in winter.The velocity in mainstream line fluctuates strongly in summer,and there are many peaks,but velocity in winteris gentle.However,the seasonal variation of the mean velocity in mainstream line is not obvious.The inter-annual variation and seasonal variation of the four typical glacier velocities are similar to those of the glaciers in the study area.There is a close relationship between velocity and climate and the shape of the glacier.The characteristics of glacier advance and retreat are not obvious,and the glaciers in the study area are in equilibrium.     

A comparison of multiple classifier combinations using different voting-weights for remote sensing image classification

Remote sensing image classification is a common application of remote sensing images. In order to improve the performance of Remote sensing image classification, multiple classifier combinations are used to classify the Landsat-8 Operational Land Imager (Landsat-8 OLI) images. Some techniques and classifier combination algorithms are investigated. The classifier ensemble consisting of five member classifiers is constructed. The results of every member classifier are evaluated. The voting strategy is experimented to combine the classification results of the member classifier. The results show that all the classifiers have different performances and the multiple classifier combination provides better performance than a single classifier, and achieves higher overall accuracy of classification. The experiment shows that the multiple classifier combination using producer’s accuracy as voting-weight (MCC_mod2 and MCC_mod3) present higher classification accuracy than the algorithm using overall accuracy as voting-weight (MCC_mod1).And the multiple classifier combinations using different voting-weights affected the classification result in different land-cover types. The multiple classifier combination algorithm presented in this article using voting-weight based on the accuracy of multiple classifier may have stability problems, which need to be addressed in future studies.     

青藏高原玛旁雍错和拉昂错水色差异遥感分析

湖泊水色是湖水光学性质之一,青藏高原地区由于其特殊的地理条件,不同湖泊水色差异十分明显。选取藏南地区玛旁雍错和拉昂错作为研究对象,从二者水色差异的遥感图像表征出发,充分借助遥感手段,对造成差异的因素进行分析。结果表明,补给和蒸发的差值不同,使湖内盐分等物质的积聚不同,进而造成二者水色的差异。该方法为青藏高原地区难以获得有效资料湖泊的研究提供了一种新思路。     

多级缓冲技术在提高电力GIS性能中的应用

通过构建多级缓冲技术,即充分结合DBMS、ARCSDE、BDB、内存Cache及多线程应用等多种技术来提高电力GIS的性能,并通过降低系统网络数据流量及对服务器端的依赖,用更高性能的BDB查询方式降低客户端的计算量,提高了查询显示速度,从而有效地提高了电力GIS系统的性能.     

Superimposition: a component adaptation technique

Several authors have identified that the only feasible way to increase productivity in software construction is to reuse existing software. To achieve this, component-based software development is one of the more promising approaches. However, traditional research in component-oriented programming often assumes that components are reused “as-is”. Practitioners have found that “as-is” reuse seldom occurs and that reusable components generally need to be adapted to match the system requirements. Existing component object models provide only limited support for component adaptation, i.e. white-box techniques such as copy–paste and inheritance, and black-box approaches such as aggregation and wrapping. These techniques suffer from problems related to reusability, efficiency, implementation overhead or the self problem. To address these problems, this article proposes superimposition, a novel black-box adaptation technique that allows one to impose predefined, but configurable types of functionality on a reusable component. Three categories of typical adaptation types are discussed, related to the component interface, component composition and component monitoring. Superimposition and the types of component adaptation are exemplified by several examples.     

Effects of power system parameters on critical clearing time: comprehensive analysis

In this paper, the effects of various power system parameters on the critical clearing time are presented. The various parameters for which the analysis is presented include the machine parameters, i.e. damping, inertia constant and transient reactance, and system parameters, i.e. line impedance, transformer impedance and fault impedance. Various configurations of faults are also investigated. The simplest single machine infinite bus power system was simulated. Plots and relationships for each parameter are presented and conclusions are drawn from their behavior. The paper is a comprehensive treatment of the time domain method to the single machine system and is particularly helpful to the utility power engineers and researchers in the electric machines area to comprehend the system behavior for various system parameters. The results can be generalized to the large scale multimachine power systems as well.     

Particle reinforcement of ductile matrices against plastic flow and creep

A theoretical investigation is made of the role of non-deforming particles in reinforcing ductile matrix materials against plastic flow and creep. The study is carried out within the framework of continuum plasticity theory using cell models to implement most of the calculations. Systematic results are given for the influence of particle volume fraction and shape on the overall behavior of composites with uniformly distributed, aligned reinforcement. The stress-strain behavior of the matrix material is characterized by elastic-perfectly plastic behavior or by power-law hardening behavior of the Ramberg-Osgood type. A relatively simple connection is noted between the asymptotic reference stress for the composite with the power-law hardening matrix and the limit flow stress of the corresponding composite with the elastic-perfectly plastic matrix. The asymptotic reference stress for the composite with the power-law matrix is applicable to steady-state creep. A limited study is reported on the overall limit flow stress for composites with randomly orientated disc-like or needle-like particles when the particles are arranged in a packet-like morphology.     

基于遥感和CA_Markov模型的煤矿区热环境与土地覆盖变化模拟评价

针对遥感影像在定量描述土地覆盖和热环境分布方面的优越性,利用支持向量机（SVM）分类器对遥感影像进行分类,获取土地覆盖图,利用单窗算法反演获取地表温度。通过将元胞自动机和马尔科夫模型结合,构建CA_Markov模型对土地覆盖和热环境时空格局进行模拟与分析。采用定量景观指数和土地利用转移矩阵进一步挖掘了研究区空间信息,综合模拟与预测了土地覆盖和热环境时空变化特征。实验结果表明：利用遥感影像定量反演热环境特征时空分布与预测是可行的,CA_Markov模型能够有效地揭示和预测矿区土地覆盖变化和热环境演变趋势。     

简单要素模型多边形拓扑检查并行算法

将并行计算应用到大数据量简单要素模型多边形拓扑检查中,设计实现了简单要素模型多边形拓扑检查并行算法。算法针对拓扑检查的计算特点,改进了主从式并行策略,在主进程中进一步划分线程以实现任务并行,从而隐藏拓扑错误提取和结果写入时间。采用MPI和PThread实现进程与线程的结合。利用苏南五市土地现状调查地类图斑数据对算法进行测试。经测试,该算法能够对大数据量简单要素模型多边形进行准确、快速的拓扑检查。算法提出的进程与线程结合的任务并行策略相对于传统主从式策略加速比提高约20%。