Virtual reality and its application to slide annimation of landslide

A few researches adopt virtual reality in landslide. So it is significant to combine the physicsbased deformable method with the process simulation of a sliding landslide, this way the dynamic process of a going landslide can be simulated. The analysis of the dynamic law of landslide provides a foundation to forecast and make it realiable to foretell disasters. After recounting the condition of VR and landsliding body simulation, this paper puts forward simulating landslide by the physics-based deformable method. The method divides landsliding into deformable body and rigid one. The deformation of deformable body can be compute by DDA and FEM, and DDA fits the great deformation and FEM is good for the tiny deformation. This paper shows it is feasible to simulate the landslide animation by this method.     

Authorization administration in a distributed multi-application environment

To meet the authorization administration requirements in a distributed computer network environment, this paper extends the role-based access control model with multiple application dimensions and establishes a new access control model ED-RBAC(Extended Role Based Access Control Model) for the distributed environment. We propose an extendable hierarchical authorization assignment framework and design effective role-registering, role-applying and role-assigning protocol with symmetric and asymmetric cryptographic systems. The model can be used to simplify authorization administration in a distributed environment with multiple applications.     

卡尔曼滤波技术在伪距法动态定位中的应用探讨

本文对动态定位数据处理中应用卡尔曼滤波方法进行研究，通过模拟数据和实测数据采用自编软件进行数据处理，并对成果进行统计分析，最后，讨论了采用卡尔曼滤波方法的缺点，得出了一些有益的结论。     

Land cover dynamics in Garhwal Himalayas — a case study of balkhila sub-watershed

The present paper focuses on land cover dynamics pattern in Balkhila sub-watershed situated in Garhwal Himalayas. This study contributes example from human shaped ecosystem in mountainous regions where fragmentation of natural resources is active. The remote sensing and GIS has been used to understand the land cover dynamics along the topography. The results report that the land cover dynamics is dependent on the aspect due to sun illumination. The altitude and slope are no more a barrier for resource extraction and the human activity zone is shifting towards higher altitudes and slopes. The changes are also defined along the road and settlements.     

An automated seamless mosaicing system of multi-charge coupled devices of panchromatic data

Panchromatic data of pixel resolution 5.8 m obtained from IRS-1C and IRS-1D satellites proved to be very useful for mapping purposes. One of the popular data product is the 70 km swath mosaic which is covered by a combination of 3 CCD line sensors, each with 4096 pixels. Each CCD-line sensor with different imaging times causes geometric problems of mosaicing three strips data together. In this paper, we propose the details of the design elements of system that caters to the need for accurate and automatic multi strip image registration without any second resampling of the data. The systematic geometric correction grid mapping is improved to facilitate accurate mosaicing by automatic image registration task that makes use of the overlap data within image strips and image registration is achieved up to sub-pixel level.     

The GPS Toolbox

The GPS Toolbox is dedicated to highlighting algorithms utilized by GPS engineers and scientists. If you have an interesting algorithm you would like to share with our readers or if you have a topic you would like to see covered in a future column, contact us at gps-toolbox@ngs.noaa.gov. To comment on the algorithms presented here, or to leave a request for an algorithm you may be looking for, visit our Web site (http://www.ngs.noaa.gov/gps-toolbox). ? 2000 John Wiley & Sons, Inc.     

Determination of failure probabilities of flood defence systems with improved dynamic bounds method

In this paper, we describe the computational framework of a novel method for solving the challenging problem of probabilistic finite elements. The method is called Improved Dynamic Bounds (IDB) and was developed recently to improve the efficiency of the dynamic bounds. The IDB is used in finite element numerical models to calculate time-dependent failure analyses of structures. In applications, the IDB can speed up the overall simulation process by several orders of magnitude. In applications controlled by two influential variables (e.g, two-dimensional problem), the computational efficiency is improved by a factor of 769 according to Rajabalinejad (2009). Applications of IDB indicate the method is most efficient for problems where the number of influential variables are limited. This is often the case for geotechnical and coastal flood defence systems. The IDB method is applied in this paper to the 17th Street Flood Wall, a component of the flood defence system (levee infra-structure) that failed during the Hurricane Katrina, to calculate the failure probability of an I-wall.     

巴音布鲁克高寒区气象观测分析

本文通过2011-2013年中天山高寒无人区自建的自动气象站获取的稀缺气象资料,客观地揭示了观测区域的气象条件,给出部分气象特征参数变化特征,为中天山高山达坂区气象观测研究工作奠定一定基础,并得出如下结果：（1）迎风坡盛行风向SE、N,SE占35%,N占25%,N向风力集中4级以下,SE明显偏大,3级风比重15%,4级风比重7%,5级风比重4%;6级风比重1%,6级以上的风力几乎为零。背风坡主导风向角度范围在247.5°-337.5°,风力基本在6级以下,6级及以上风力出现概率不足1%。3-5级风占的比重较大。（2）日平均气温≤-10℃日数所占观测总日数的百分比,其值分别为：0.0%（恰西）、44.5%（江不肯达坂）、9.8%（江巴口子）、15.1%（铁力买提达坂）。恰西、江不肯达坂、江巴口子、铁力买提达坂4站日平均相对湿度≥80%的频率分别为5.9%、18.4%、16.1%和22.6%。（3）换算得出恰西、江不肯达坂、江巴口子、铁力买提达坂观测期间10m高度最大瞬时风速与小时平均风速分别为33.8/27.9m/s、41.0/27.3 m/s、25.7/17.7m/s、34.0/17.2 m/s。     

Variation in Coronal Activity from Solar Cycle 24 Minimum to Maximum Using Three-Dimensional Reconstructions of the Coronal Electron Density from STEREO/COR1

Three-dimensional electron density distributions in the solar corona are reconstructed for 100 Carrington rotations (CR 2054?–?2153) during 2007/03?–?2014/08 using the spherically symmetric method from polarized white-light observations with the inner coronagraph (COR1) onboard the twin Solar Terrestrial Relations Observatory (STEREO). These three-dimensional electron density distributions are validated by comparison with similar density models derived using other methods such as tomography and a magnetohydrodynamics (MHD) model as well as using data from the Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO)-C2. Uncertainties in the estimated total mass of the global corona are analyzed based on differences between the density distributions for COR1-A and -B. Long-term variations of coronal activity in terms of the global and hemispheric average electron densities (equivalent to the total coronal mass) reveal a hemispheric asymmetry during the rising phase of Solar Cycle 24, with the northern hemisphere leading the southern hemisphere by a phase shift of 7?–?9 months. Using 14 CR (\(\approx13\)-month) running averages, the amplitudes of the variation in average electron density between Cycle 24 maximum and Cycle 23/24 minimum (called the modulation factors) are found to be in the range of 1.6?–?4.3. These modulation factors are latitudinally dependent, being largest in polar regions and smallest in the equatorial region. These modulation factors also show a hemispheric asymmetry: they are somewhat larger in the southern hemisphere. The wavelet analysis shows that the short-term quasi-periodic oscillations during the rising and maximum phases of Cycle 24 have a dominant period of 7?–?8 months. In addition, it is found that the radial distribution of the mean electron density for streamers at Cycle 24 maximum is only slightly larger (by \(\approx30\%\)) than at cycle minimum.