Showing papers by "Geophysical Survey published in 2008"

Scattering analysis of ground-penetrating radar data to quantify railroad ballast contamination

Abstract: This paper will evaluate ground-penetrating radar (GPR) as a non-destructive method to rapidly, effectively, and continually assess the conditions of railroad ballast. Compared to uniformly graded, clean ballast, fouled ballast has a finer, well-graded particle size with fewer air voids. Ballast under different conditions generates various GPR electromagnetic scattering patterns. A field GPR survey with multiple sets of 1 and 2 GHz air-horn antennae was conducted in summer 2005 at the Transportation Technology Center, Inc. (TTCI) in Pueblo, Colorado. The 2 GHz antenna was found to be more sensitive to the change in scattering pattern. Appropriate data processing was used to remove the effects of the rails to obtain clear GPR images of the subsurface layers. From the image analysis, ballast thickness, ballast fouling condition, and trapped water can be assessed.

Time-Frequency Approach for Ground Penetrating Radar Data Analysis to Assess Railroad Ballast Condition

Abstract: Railroad ballast plays an important role in supporting heavy rail loading, preventing the deformation of track, and providing drainage of water from the track structure. However, over time, ballast is fouled by the breakdown of ballast aggregate and/or the infiltration of fines, which undermine ballast functions. This may result in damage to the rail system, such as track settlement. Ground penetrating radar (GPR), a nondestructive method, can be used to rapidly, effectively, and continuously assess railroad track substructure conditions. Ballast under various fouling conditions generates various electromagnetic (EM) scattering patterns. In this study, air-coupled 2 GHz antenna was found to be sensitive to the scattering pattern change. Appropriate data processing was used to remove the effects of ties and rails to obtain clear GPR images of the subsurface layers. Then, the amplitude envelope and time-frequency approaches were implemented to characterize the signal in time and frequency domains simultaneo...

Atmospheric correction of hyperspectral data using MODTRAN model

Abstract: The solar radiance obtained by a sensor is modified by atmosphere interaction, affected by its path through the atmospheric absorption and scattered in the combined Sun-surface-aircraft. In this paper, we described a method using RTM to simulate atmospheric spectral for deriving surface reflectance from Hyperspectral data (Hyperion). Preliminary application of the technique to Hyperion data indicates that the retrieval results are reasonable, and available techniques including retrieval of water vapor amount with MODTRAN look-up- table.

Experiment study on quantitative retrieval of mineral abundances from reflectance spectra

Abstract: Quantitatively retrieving mineral abundances from hyperspectral data is one of promising and challenging geological application fields of hyperspectral data, and the most basic obstacles are mixture characteristic of mineral spectra and deconvolution method of mixture spectra. A series of mineral mixture schemes were designed, and several kinds of mineral were used for investigating the two obstacles. In the experiment, average single scattering albedo was calculated from reflectance spectra on the basis of Hapke radiative transfer model. The error of mineral abundances derived from reflectance spectra and single scattering albedo is 20.05% and 5.03% respectively, which shows that mixture spectra of all kinds of mineral belongs to nonlinear mixing, and Hapke model is a good method of resolving this problem. Finally, deconvolution of continuum-removed single scattering albedo spectra other than single scattering albedo spectra is considered to be the possible method that could be applied to imaging spectrometer data (e.g. AVIRIS and Hyperion data) to retrieve mineral abundances successfully, because intensity of spectra is influenced by terrain considerably rather than shape of spectra feature is influenced by terrain slightly.

The main evolution of remote sensing for land resources of China in recent years

Abstract: The development of earth observation techniques has expanded and deepened the application area of remote sensing further. Meanwhile, the application on remote sensing for land resources has entered a new era marked by high spatial resolution, high spectral resolution and high temporal resolution. Nowadays, remote sensing techniques serve as an important support for the great discovery of geosciences and the modernization of geological work. The remote sensing satellites of our country develop to groups, networks and seriations; its application area develops to fine and quantitative direction; the recent researches both in basic field and application area develop to integration. In the following years, the need for remote sensing application will be more and more imminent. It is an inevitable tide for land remote sensing to use all-weather and multi-angle observation system by which we can observe the earth real-time to survey, suspect and research the resources, energy, and environment What is more, impractical hyper-spectral remote sensing system is an urgent technical platform problem to be solved for further application in remote sensing for resources and energy.

Dynamic changes of lakes and the geo-mechanism in Tibet based on RS and GIS technology

Abstract: Using the topographic data at the scale of 1:100000 in 1960´s, and Landsat MSS in 1970´s, Landsat TM in 1990´s, Landsat ETM+ in 2000´s, we carried out the survey of the lake distribution and its dynamic changes on Tibetan Plateau. The result indicates that there are 3 lakes within the area more than 1000km 2 , 74 lakes within area more than 100km 2 , 382 lakes within the area more than 10km 2 , 1260 lakes with the area more than 1km 2 , 6882 lakes within the area more than 0.1km 2 , and the total area of lakes is about 43186.4km on Tibetan Plateau. The area of lakes has taken place significantly changes during the past 30 years. The total area of lakes has increased 1610.01km 2 . The area of increased lakes are 157 lakes with in area more than 1km 2 , 5411 lakes within area more than 0.1km 2 and small lakes increased in hundreds and thousands. The area and amount of lakes increase most obviously in Qiangtang Plateau and Kunlun Mountains, and decrease most obviously in Qaidam basin, Hexi Corridor, Yellow River Basin, Yarlung Zangbo River Basin. The expanded and newborn lakes are distributed in the inner Plateau and disappeared and decreased lakes in the surrounding area of the Plateau. The increase and decrease of lake area has some related with climate changes, but mainly related to the local topography controlled by neo-tectonic. Keywords: Topographic map ÷ Landsat data ÷ lake ÷ lake area change ÷ Tibetan Plateau Tibetan Plateau is the most concentrated area of lake and wet land in China

Detection and evaluation on phosphorite mining environment contamination sources using ASTER and DEM

Abstract: The main environment contamination source of the phosphorite mining area, located in Huji city, Hubei province, China, was detected and evaluated using ASTER and DEM. Firstly, the featured spectrum that has unique diagnose spectral feature was generalized after analyzing the types and spectrum characteristics of the sample contamination source in the area. Secondly, the main contamination source of the area was recognized by means of principal component analysis using ASTER band 1-9. And the distributions of them were in accordance with that of phosphorite, carbonate and waste water. Finally, flow accumulation and catchment images were simulated using DEM and GIS. By analyzing the images of the flow accumulation, catchment and contamination source, the authors conclude that large scale opencast phosphorite mining and solid waste materials have damaged mining environment; the disordered piling of solid waste material has been boosting diffusion and migration of harmful and toxic matters; and all of these has damaged heavily ecological environment of lower reaches, and is the potential unsafe factor for that of Hanjiang river also. Keywords: ASTER, DEM, mining contamination, detection and evaluation on contamination sources 1.

Urban change detection of integrating remote sensing and GIS: taking Tianjin City for example

Abstract: One Landsat5 TM image of 1993/6/15 and one Landsat7 ETM+ image of 2001/5/12 about Tianjin whose path/row are both122/33 have been used for this study. An integrated RS and GIS approach is presented for change detection. Based on summarizing the methods of change detection and analyzing the disadvantages of traditional approaches, multivariate alteration detection based on the canonical correlation analysis is introduced. Firstly, canonical transform is adopted for the preprocessed images. Then, the sixth component containing the maximal change message is processed and the change message is extractd. Moreover, the binary image is vectorized and the vectorized maps are overlapped with the original images separately. So the change about two time phases is compared. Subsequently, the database is established based on the basic space data such as road maps and maps showing present condition of land utilization and urban planning maps as well as humane and socio-economic data. The results rooting in the image change detection are entered into GIS by vectorization and spatial overlay analyzed with already existent data. Finally, the urban built-up area is extracted and the validated precision is high. The urban expansion areas and dynamic change characteristic and reasons in Tianjin from 1993 to 2001 have been revealed and discussed. Comparing with the Tianjin city master planning (1996-2010), it shows that urban expansion change is coincident with urban planning implementation.

The study in deformation and destruction mechanism of Qianjiangping landslide in Three Gorges Reservoir area

Abstract: The advanced digital image processing technique was used in the high resolution remote sensing images processing, aero photos before landslide happened and the Quick Bird image after landslide were processed. The technique of digital landslide, 3D visualization and man-machine interactive interpretation were used to analyze the geomorphologic features of remote sensing images. From the characteristic of the deposit, it is deduced that the paleo-landslide was a deep and consequent rock landslide with large-scale deposit, the entire deposit of "7.13" landslide is similar to the paleo-landslide, and the displaced volume is 15×106m3. Based on the geology theory, this paper synthetically compared the effect of landslide between the rainfall and the water level rising. It is concluded that the main inducing factors is the first stage storage of the Three Gorges and the continuous rainfall is triggering factor. Synthetically analyzing the process of slide and the characteristic of deposit, it is deduced that the middle and front part of Qianjiangping landslide is push-type sliding while the back part is drag sliding, the pattern of deformation and destruction is front verge leading sliding-drag.

Research on land use/cover change of opencast coal mining area of Pingshuo Shanxi

Abstract: The Pingshuo open-cast coal field is located in the Shuozhou district, north of Shanxi, China. It is a part of wider region known as the Black Triangle. Open-cast coal mining has caused total destruction of original ecosystems, as well as changes of relief and also land use/cover changes (LUCC) in the mining areas. This paper presents a case study on land use/cover change , and analyzes the LUCC extracted from the TM (ETM+) image data taken from 1986, 1990, 1995, 2002, and 2005. Here comes the results: With the turning of the structure of the mining area land from undisturbed land to land both undisturbed and disturbing, there is the coexistence of undisturbed land, disturbing land and reclaimed land; On the quantity side, from 1986 to 2005, the area of undisturbed land has reduced from 36601.0 ha to 33379.51 ha , while the area of disturbing land has increased from 911.25 ha to 3206.36 ha , and the reclaimed land from 0 ha to 926.46 ha. The area of original land will decrease to 4425.8 ha, as predicted; The spatial evolution, under the obvious limitations of mining order and planning, is presenting a gradient change form from undisturbed land to disturbing land and then to reclaimed land, that is, the spatial scale of reclaimed land is expanding while the undisturbed land is narrowing gradually.

Extraction and monitoring of Karst rock desertification information

Abstract: Karst Rock desertification is one of the ecological geology problems in southwest of China. The investigation of this problem can provide scientific evidence for its evolution analysis and post arrangement, so monitoring the dynamic change of desertification using quick, precise and economic method is the most important task. In this paper, the fundamental remote sensing dynamic monitoring theory and method is applied, and it mainly discussed these aspects including remote sensing data choice, data preprocessing, extraction of rock desertification change information, classification of rock desertification information, etc. It summed up the technologic route and method of the Karst rock desertification monitoring using remote sensing technology. Based on the research of testing area and random sample investigation, it is indicated that the result using this method is precise and satisfying.

Method for extraction of quantitative information using remote sensing data of underground coal fire areas and its application

Abstract: Underground coal-bed spontaneous combustion is a dynamic process with complex physical, chemical and environmental interaction. The anomalous information on remote sensing spatial, spectral and thermal indexes is very meaningful for detecting underground coal fires and assessing its effects on environment. This paper, based on a series of advanced technical datum in Wu Da coalfield areas located in Inner-Mongolia, such as ground spectral testing, thermal infrared multispectral indexes, and high-spatial resolution images, analyzes the correlation between the underground coal-bed burning conditions and the remote sensing information. Besides, it provides a further discussion on the application potential for quantitative feature extraction of underground coal fire.