Tracking and evolution of complex active landslides by multi-temporal airborne LiDAR data: The Montaguto landslide (Southern Italy)

A multi-temporal LiDAR study of an active landslide at Montaguto (Italy) is presented. Four LiDAR-derived Digital Terrain Models acquired on May 2006, July 2009, April 2010 and June 2010 are used. The interpretation of selected morphometric parameters (surface roughness, residual topographic surface) and the statistical analysis of the temporal variations of such parameters allowed the reconstruction and tracking of the landslide. The landslide boundary monitoring was achieved and zones of uplift and subsidence, volumes of removed and/or accumulated material, and average rates of vertical and horizontal displacement (retreat rate of the crown and advancement rate of the toe) were estimated. Deformation structures (scarps, cracks, folds) affecting the landslide in different times were also mapped; some of such structures represent precursors of impending instability processes or give information on the mechanism of emplacement. Various types of activity (e.g. rock-fall, flow) and geometry (e.g., channelized flow) are recognized and zones whose topographic features change with time due to artificial drainage and earth handling/removal work were detected. The LiDAR-derived information allows us to decipher the kinematics of the landslide. The results provide new insight on the use of airborne LiDAR in the monitoring strategies of gravity-controlled processes.     

Influence of Various Albumin Concentrations on the Corrosion Resistance of Zr-2.5%Nb Alloy

The Zr-2.5% Nb alloy corrosion resistance in four saline solutions with and without albumin was tested through electrochemical measurements of electrochemical impedance spectroscopy (EIS), linear polarization, and cyclic voltammetry at human body temperature.

The EIS measurements were performed at open circuit potential. The impedance spectra were recorded and the equivalent electric circuits were elaborated. From the linear polarization the Tafel slopes were recorded and the corrosion parameters were calculated. From the potentiodynamic polarization curves, the breakdown potential, the protection potential, and the protection domain were observed.

The amount of ions released from the material was quantified using the ICPMS technique and the results concerning the corrosion resistance were compared with those obtained from linear and cyclic polarization.

Before and after potentiodynamic polarization the topographic measurements were performed; the roughness at the samples surface was observed using AFM. The roughness was co-related to the contact angle measurements.     

彩色地图分色算法的改进及实现

在加权模糊c-均值（FCM）聚类算法的基础上,对分色算法进行了改进．首先进行色彩空间模型转换,然后对基于样本加权的FCM算法进行改进,对隶属度进行调整,把二维彩色直方图引入加权系数中．对于模糊c-均值算法,当隶属度接近时,分类会变得模糊,而且对于不同的样本矢量,聚类效果有所不同,本算法兼顾到了这两点．该方法已用Visual C＋＋6．0编程实现,效果比较理想．     

Projection of topographic maps from curved brain surfaces into a plane

The environment is represented in the brain by topographic maps. These maps and their interrelationship form a dominant feature in the brain, but unfortunately, they are often projected onto surfaces which are variously curved. It would be useful to be able to compare the topography on these surfaces quantitatively with the origin of the map. This comparison would be possible if the curved brain surfaces could be represented in planes. Therefore, it was necessary to develop a procedure for unfolding maps on convex structures like the retina and the optic tectum of the chick. For this purpose a unit sphere was constructed whose origin was close to the centre of gravity of the curved brain structure. The surface of this structure was then projected into the sphere. From its representation on the spherical surface it was unfolded into the plane using a polar azimuthal radially equidistant projection. Our method can safely be applied to convex structures only. However, it is not limited to the visual system. The mathematical procedure is formulated in such a way as to be easily implemented. It is exemplified by experiments on the optic tectum and the developing retina of the chick.     

地形条件对次生山地灾害易发性分析

岷江上游河谷地带位于汶川地震极震区,是中国乃至世界上地震次生山地灾害最为活跃的地区之一,其频繁活动与复杂的地形条件密切相关.以岷江河谷汶川段为典型研究区,在分析了地理环境和地形条件的基础上,研究了地震次生山地灾害的类型、发育特征、分布状况和主要地形影响因素,并基于次生山地灾害形成因素贡献率,引入确定性系数,利用GIS和RS技术,定量分析了高程、坡度和坡向3个主要地形因子对次生山地灾害的易发程度,确定了最利于次生山地灾害发生的地形条件.研究结果表明:1)地震次生山地灾害具有点多面广、类型多样、分布集中、规模巨大等特征,并受地形条件控制;2)利于次生山地灾害发生的高程条件为1 000～1 600 m的高程范围,高程大于1 600 m的区域,山地灾害随海拔升高而越不易发生;3)坡度大于35°的中陡坡地带,均利于次生山地灾害的发生,且随坡度增大,灾害发生的可能性也增大;4)有利于次生山地灾害发生的坡向条件依次为东南、东、南和东北4个方向,其CF分别为0.169、0.144、0.135和0.023;5)利用GIS和统计分析方法,能定量进行地震次生山地灾害易发性分析.研究方法可以为灾区次生山地灾害风险评价与区划提供依据,研究成果对灾区山地灾害防治规划、保障重大工程建设安全和减少灾害损失等具有参考意义.     

Airborne Laser Terrain Mapping for Expediting Highway Projects: Evaluation of Accuracy and Cost

A typical highway project generally takes 5 years or more from planning phase to construction stage, particularly in wooded and difficult terrain using traditional topographic terrain mapping methods. This paper presents an application of airborne laser terrain mapping technology for a 9?km (5.9?mi.) long highway project in a difficult densely wooded terrain with steep slopes and ravines. Elevation data accuracy, efficiency, and cost effectiveness were compared with the traditional aerial photogrammetry and ground based total station survey methods. The elevations of centerline and 15 different cross sections were compared with groundtruthing data from the total station survey. Using appropriate flight mission parameters, the airborne laser technology permits elevation accuracy of 0.13?m (5?in). There are less operating constraints which adversely affect the productivity of traditional methods, such as cloud and vegetation cover, time of day, and intrusion into private properties. It is recommended to combine the low-altitude airborne laser technology with centerline staking by total station survey and aerial photography. The recommended combined approach saves 33% of the budget and 35% of time.     

扫描隧道显微镜轮廓测量数学模型的研究

在量子隧道效应的基础上,建立了适用于增坦表面的扫描隧道显微镜微观轮廓测量的数学模型,并采用傅里叶变换方法对该模型进行了仿真验证。仿真结果表明,该模型较好地反映了扫描隧道显微镜对样品表面轮廓的测量过程。最后,中还对该模型的适用范围进行了讨论。     

基于数学形态学的地形图自动矢量化研究

概要介绍了数字流域系统中地形图自动矢量化子系统的结构框架及基于数学形态的细化算法模型，滤波算法模型，图文分割的算法模型；分析了渐次扩大多结构元素串联式滤波算法，移动矩形的节点数据压缩算法，在地形图自动处理实践中，证明了多结构元素的选择与组合及算法的高效可行性及系统设计的合理性。     

一种新的地形图汉字注记自动提取算法

地形图中包含大量的汉字注记,为了实现地图要素自动识别,首先要将文字正确地提取出来。该文通过对汉字特征的分析,提出了一种新的汉字提取算法。首先根据地图图像的特点进行骨架运算,利用形态算子对汉字笔画进行分解,最后实现对汉字注记的笔画统计提取。该算法较好地解决了字线粘连、旋转等情况下的汉字提取问题,具有良好的稳定性。     

A fast and robust bulk-loading algorithm for indexing very large digital elevation datasets II. Experimental results

The spatial indexing of eventually all the available topographic information of Earth is a highly valuable tool for different geoscientific application domains. The Shuttle Radar Topography Mission (SRTM) collected and made available to the public one of the world's largest digital elevation models (DEMs). With the aim of providing on easier and faster access to these data by improving their further analysis and processing, we have indexed the SRTM DEM by means of a spatial index based on the kd-tree data structure, called the Q-tree. This paper is the second in a two-part series that includes a thorough performance analysis to validate the bulk-load algorithm efficiency of the Q-tree. We investigate performance measuring elapsed time in different contexts, analyzing disk space usage, testing response time with typical queries, and validating the final index structure balance. In addition, the paper includes performance comparisons with Oracle 11g that helps to understand the real cost of our proposal. Our tests prove that the proposed algorithm outperforms Oracle 11g using around a 9% of the elapsed time, taking six times less storage with more than 96% of page utilization, and getting faster response times to spatial queries issued on 4.5 million points. In addition to this, the behavior of the spatial index has been successfully tested on both an open GIS (VT Builder) and a visualizer tool derived from the previous one.