区域似大地水准面确定的最小二乘支持向量机方法     

范千  张宁 《测绘工程》2008,17(5)

支持向量机(SVM)是近年来发展起来的机器学习的新方法,它较好地解决小样本、非线性、高维数、局部极小点等实际问题.文中研究支持向量机的拓展算法--最小二乘支持向量机(LSSVM),并将其应用于确定大面积复杂似大地水准面.通过工程实例并与神经网络模型和二次曲面多项式拟合模型相比较,验证确定区域似大地水准面的LSSVM方法的有效性.  相似文献   

天宝GEOXT数据采集模式及精度研究     

谢宏全  周立  马迁  吴少辉 《测绘工程》2008,17(4):1-3

随着经济的不断发展,移动GIS越来越受到人们的关注,而GEOXT的出现正是符合这一发展趋势的产物。GEOXT这一款仪器将GPS与GIS结合在一起,利用GPS技术得出GIS的成果。文中在说明天宝GEOXT数据采集系统配置及特点的基础上,通过实验总结了数据采集的3种模式：单机码相位测距、后差分改正和实时差分改正数据采集,并对数据采集的技术流程、点位精度、特点和应用范围进行了阐述。最后对不同采集时间间隔对精度的影响进行了试验研究。  相似文献   

Automated Target Detection and Discrimination Using Constrained Kurtosis Maximization   总被引：1，自引：0，他引：1  

Qian Du Kopriva  I. 《Geoscience and Remote Sensing Letters, IEEE》2008,5(1):38-42

Exploiting hyperspectral imagery without prior information is a challenge. Under this circumstance, unsupervised target detection becomes an anomaly detection problem. We propose an effective algorithm for target detection and discrimination based on the normalized fourth central moment named kurtosis, which can measure the flatness of a distribution. Small targets in hyperspectral imagery contribute to the tail of a distribution, thus making it heavier. The Gaussian distribution is completely determined by the first two order statistics and has zero kurtosis. Consequently, kurtosis measures the deviation of a distribution from the background and is suitable for anomaly/target detection. When imposing appropriate inequality constraints on the kurtosis to be maximized, the resulting constrained kurtosis maximization (CKM) algorithm will be able to quickly detect small targets with several projections. Compared to the widely used unconstrained kurtosis maximization algorithm, i.e., fast independent component analysis, the CKM algorithm may detect small targets with fewer projections and yield a slightly higher detection rate.  相似文献   

米仓山南缘中生代沉积盆地性质讨论   总被引：2，自引：0，他引：2       下载免费PDF全文

牟传龙  谭钦银  余谦 《沉积与特提斯地质》2008,28(3):41-45

米仓山南缘位于四川盆地北部地区,前人认为该地区晚三叠世-白垩纪受控于米仓山造山作用形成的前陆盆地.实际上,无论是按照经典的前陆盆地概念,还是陆内前陆盆地或陆内俯冲前陆盆地等术语,米仓山南缘中生代为前陆盆地值得商榷,其一些关键的地质问题必须给以重视.主要表现在:①平面构造图显示,米仓山地区,前震旦系基底与震旦系盖层之间构成一规模较大的不完整的背斜穹隆,盖层围绕基底分布,说明不是构造推覆体;②不存在形成前陆盆地的区域应力,即该区在晚三叠世开始主要是升隆作用而非强烈的推覆挤压,研究资料表明该地区大规模的逆冲推覆作用发生在燕山期,米仓山的形成也应在该时限之内,之前米仓山为一继承性的隆起;③不具备前陆盆地的沉积格局,即晚三叠世-侏罗纪的沉积格局不是呈楔形展布.鉴于此,笔者认为前陆盆地术语不适用于米仓山南缘晚三叠世-侏罗纪沉积盆地的类型.  相似文献   

Pyrometamorphic rocks of the spurrite-merwinite facies as indicators of hydrocarbon discharge zones (the Hatrurim formation,Israel)     

E. V. Sokol  I. S. Novikov  S. N. Zateeva  V. V. Sharygin  Ye. Vapnik 《Doklady Earth Sciences》2008,420(1):608-614

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非量测数码影像在航测成图中的应用     

郑福海  刘倩  王铁军 《测绘与空间地理信息》2008,31(5)

如何加速成图周期,快速、高效地生产各种地理信息产品是摄影测量应用研究的主要内容.本文介绍了非量测数码航摄影像在全数字摄影测量工作站上进行地理信息产品生产的技术方法和工作流程,研究了关键技术环节.  相似文献   

Response of riparian vegetation to water-table changes in the lower reaches of Tarim River, Xinjiang Uygur, China   总被引：1，自引：0，他引：1  

Yaning Chen  Zhonghe Pang  Yapeng Chen  Weihong Li  Changchun Xu  Xinming Hao  Xiang Huang  Tianming Huang  Zhaoxia Ye 《Hydrogeology Journal》2008,16(7):1371-1379

The lower reaches of Tarim River in the Xinjiang Uygur region of western China had been dried out for more than 30 years before water began to be diverted from Konqi (Peacock) River via a 927-km-long channel in year 2000, aimed at improving the riparian ecological systems. Since then, eight intermittent water deliveries have been carried out. To evaluate the response of riparian vegetation to these operations, the groundwater regime and vegetation changes have been monitored along the 350-km-long stem of the river using a network of 40 dug wells at nine transects across the river and 30 vegetation plots at key sites. Results show that the water table rose remarkably, i.e. from a depth of 9.87 m before the water delivery to 3.16 m after the third water delivery. The lateral distance of affected water table extended to 1,050 m from the riverbank after the fourth water delivery. The riparian vegetation has changed in composition, type, distribution, and growing behavior. This shows that the water deliveries have had significant effects on restoration of riparian ecosystems.  相似文献   

塔里木盆地塔中低凸起地层水化学特征对不整合的响应          下载免费PDF全文

曾溅辉  吴琼  钱诗友  孔旭  马中良 《古地理学报》2008,10(5)

对塔中低凸起地层水化学特征与不整合之间关系的研究结果表明,地层水化学特征对不整合具有很好的响应。在遭受强烈抬升和剥蚀、之间形成不整合的奥陶系和志留系,以及紧靠不整合面附近的石炭系CⅢ油组,其地层水具有矿化度、Cl-含量、K Na 含量和r(Cl-Na)/rMg值相对较小,而HCO3-含量、rNa/rCl值和rSO42-×100/rCl值相对较大的特点,反映出地质历史时期大气降水的影响。在志留系与石炭系之间以及志留系与奥陶系之间的不整合面附近,地层水的矿化度、r(Cl-Na)/rMg值和B3 含量变小,而rNa/rCl值和rSO24-×100/rCl值变大,具有典型的遭受大气淋滤的地层水化学基本特征。  相似文献   

An essay on the interactions between climate and society     

Michael H  GLANTZ  Qian YE 《Frontiers of Earth Science》2008,2(3):356-363

There has been increasing concern about the lack of involvement by social scientists and humanists in a global change program, although many social scientists are already directly involved in various aspects of research on environmental change, and their research interests are clearly central to a global change research agenda. Based on a historical review, the role of social science disciplines as well as social science institutes in an emerging multidecadal global change program is discussed. Both “plan of action” and “plan of inaction” are suggested to avoid potential pitfalls due to the rush development of a social science program into the existing global climate change problem.  相似文献   

微生物对碳酸盐岩的风化作用   总被引：7，自引：0，他引：7  

连宾  陈烨  朱立军  杨瑞东 《地学前缘》2008,15(6):90

微生物-矿物相互作用可以促进许多表生生物地球化学反应过程,是表生地球化学研究的重要内容。通过综合岩石表面的微生物类群及其地质作用,分析碳酸盐岩微生物风化的各种现象,特别是微观尺度上的各种形态,阐述碳酸盐岩的微生物风化机制与风化产物,笔者提出微生物对碳酸盐岩风化的4种途径:(1)通过微生物在岩石表面和缝隙中生长,导致岩石表层发生生物溶蚀、生物磨蚀和生物钻孔作用,加速岩石风化进程;(2)微生物群体形成的钻孔网络可以增强岩石化学溶蚀的有效表面积并导致其表面强度减弱而促进机械侵蚀作用,微生物对周围岩石颗粒胶结结构的破坏、疏松作用也会导致岩石矿物颗粒的分解;(3)微生物的持水作用,微生物分泌的有机酸以及微生物呼吸所释放的CO2对岩表水分的酸化过程亦加速岩石矿物的分解;(4)微生物生长过程中从岩石内摄取营养元素和产生复杂的有机配体,能促进矿物元素的释放。文中提出在开展微生物对碳酸盐岩风化过程和机理研究的基础上,有必要引入微生物生物技术来综合开发本地低品位含钾磷矿产资源,加速岩溶地区山地土壤的形成与演化。  相似文献