Key Laboratory of Non ferrous Resources and Geological Hazard Detection

Hunan, China

Key Laboratory of Non ferrous Resources and Geological Hazard Detection

Hunan, China
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Ren Z.,Central South University | Ren Z.,Key Laboratory of Non Ferrous Resources and Geological Hazard Detection | Chen C.,Central South University | Tang J.,Central South University | And 6 more authors.
Geophysics | Year: 2017

A closed-form formula is developed for the full magnetic gradient tensor of a polyhedral body with a homogeneous magnetization vector. It is based on the direct derivative technique on the closed form of the magnetic field. These analytical expressions are implemented into an easy-to-use C++ package which simultaneously calculates the magnetic potential, the magnetic field, and the full magnetic gradient tensor for magnetic targets. Modern unstructured tetrahedral grids are adopted to represent the polyhedral body so that our code can deal with arbitrarily complicated magnetic targets. A prismatic body is tested to verify the accuracies of our closedform formula. Excellent agreements are obtained between our closed-form solutions and solutions of a prismatic magnetic body with differences up to machine precision. A pipeline model is used to demonstrate its capability to deal with complicated magnetic targets. This C++ code is freely available to the magnetic exploration community. © 2017 Society of Exploration Geophysicists.


Wei D.,Central South University | Wei D.,Central South University of forestry and Technology | Wei D.,Key Laboratory of Non ferrous Resources and Geological Hazard Detection | Zhou X.,Central South University | Zhou X.,Key Laboratory of Non ferrous Resources and Geological Hazard Detection
Cehui Xuebao/Acta Geodaetica et Cartographica Sinica | Year: 2017

Remote sensing image change detection is an important part of global change research. The change detection methods based on two-temporal remote sensing images consist of drawbacks which affect the accuracy of change detection results, such as rigorous data requirements, inadequate adoption of multi-source remote sensing image data. At present, there are some existing classification vector dataset available for change detection in many regions, and some prior knowledge are included in the existing classification vector dataset, e.g., the position, shape, size and class. Making full use of the prior information is beneficial to improve the accuracy of change detection result. Extracting changed image objects is the key step in the change detection using the existing vector data and the latest remote sensing image, Therefore, a new change detection method based on texture feature contribution is proposed. The vector data is used to segment remote sensing image, the image objects can be extracted, and the texture feature value of image objects can be calculated. According to the principle of information gain, the feature contribution of texture feature parameters is defined, and it is used to select texture feature parameters for texture feature analysis. A similar coefficient of texture feature is defined and is used to extract changed image objects. The experimental results show that selecting texture feature parameters based on feature contribution can effectively improve the accuracy of extracting changed image object result. © 2017, Surveying and Mapping Press. All right reserved.


Wu Y.,Central South University | Wu Y.,Key Laboratory of Non Ferrous Resources and Geological Hazard Detection | Zhang K.,Central South University | Zhang K.,Key Laboratory of Non Ferrous Resources and Geological Hazard Detection | And 2 more authors.
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2017

Lateral restraint technique can effectively reduce the ground settlement during the treatment practice of soft soil foundation. Based on the characteristics of road engineering and engineering properties of soft soil, the effect of lateral restraint (pile) on the settlement of composite foundation reinforced by flexible pile (rammed soil-cement pile) was studied by means of model experiment and numerical simulation. Furthermore, the changing patterns of pile and soil settlement with the loading level were analyzed, and the influence of soil modulus and pile spacing on foundation settlement was discussed taking the lateral restraint condition into consideration. The results revealed that when lateral restraint piles were applied to the composite foundation reinforced by flexible pile, the pile spacing of 2d (d is pile diameter) and 3d both reduced the pile settlement effectively if soil compression modulus was low; as the soil compression modulus increased, the settlement reducing effects decreased when pile spacing was 3d, and it increased when pile spacing was 2d, while the settlement reducing effects can hardly be observed when pile spacing was 4d. However, as the piles spacing was 2d and 3d, the reducing effect to soil settlement decreased first and then increased; when pile spacing of 4d was applied, the reduced amount of the settlement was around 4%-5%. Therefore, a reasonable setting of lateral restraint pile was required for effectively restricting the lateral extrusion of soft soil, and consequently reducing the settlement of composite foundation. © 2017, Science Press. All right reserved.


du H.-K.,Central South University | du H.-K.,Key Laboratory of Non ferrous Resources and Geological Hazard Detection | Ren Z.-Y.,Central South University | Ren Z.-Y.,Key Laboratory of Non ferrous Resources and Geological Hazard Detection | And 2 more authors.
Studia Geophysica et Geodaetica | Year: 2016

A novel finite-volume approach for complicated 2D magnetotellurics (MT) problems with arbitrarily surface topography is presented. An edge-surface integral balance equation is derived by employing a conservation law on the generalized 2D MT boundary value problem. A triangular grid is used to discretize the 2D conductivity model so that we can deal with arbitrarily complex cases with surface topography. The node-centered finite-volume algorithm is used to derive the final system of linear equations on a dual mesh of the triangular grid, which is solved by a robust direct solver. Three synthetic models verify the accuracy of the presented finite-volume algorithm and its capability of dealing with surface topography. © 2016 Institute of Geophysics of the ASCR, v.v.i


Guo Z.-W.,Central South University | Guo Z.-W.,Key Laboratory of Non Ferrous Resources and Geological Hazard Detection | Liu J.-X.,Central South University | Liu J.-X.,Key Laboratory of Non Ferrous Resources and Geological Hazard Detection | And 7 more authors.
Progress in Electromagnetics Research Symposium | Year: 2010

As an advanced technology, Ground-Penetrating Radar (GPR) is a geophysical method based on electromagnetic wave propagation commonly used for nondestructive subsurface imaging, including thruway, glacier, permafrost and pipe. It has also been used as a geophysical method in permafrost research to map subsurface structures and composition. The Qinghai-Tibet Plateau is the world's highest plateau, averaging over 4000 meters above sea level and covering an area of 200,000 square kilometers. The Qinghai-Tibet railway has always been puzzled by permafrost. It is imperative to detect permafrost subgrade fast. Permafrost recognition algorithm was proposed with applying the rolling power spectrum. In the Central South University, we did a test. As a result, it has shown that anomalies have been significantly strengthened. The most important points of this study, related to methodology and processing, are discussed, and finally, a method is proposed using data processing for permafrost detection.


Guo Z.-W.,Central South University | Guo Z.-W.,Key Laboratory of Non Ferrous Resources and Geological Hazard Detection | Liu J.-X.,Central South University | Liu J.-X.,Key Laboratory of Non Ferrous Resources and Geological Hazard Detection | And 4 more authors.
Progress in Electromagnetics Research Symposium | Year: 2010

To survey the frozen earth roadbed of Qinghai-Tibet railway and to treat the hidden trouble of the roadbed are the important approach to steady the roadbed. And it is essential guaranteed to be open to traffic in security. According to the geological data of the typical testing section of Qinghai-Tibet railway, the field experiments are accomplished. Based on the processing results, a significant technology for practical application of ground penetrating radar in detecting frozen roadbed is useful and indispensable.


Zhang W.,Central South University | Zhang W.,Key Laboratory of Non ferrous Resources and Geological Hazard Detection | Liu J.-X.,Central South University | Liu J.-X.,Key Laboratory of Non ferrous Resources and Geological Hazard Detection | And 4 more authors.
Progress in Electromagnetics Research Symposium | Year: 2010

Induced polarization method (IP) is based on rock, ore, metal induced polarization effects to find and solve hydro-geological, engineering geological issues such as a group of electrical prospecting methods. It consists of DC-induced polarization method (time domain method) and the exchange of induced polarization method (frequency-domain method). At present, Frequency- domain induced polarization method (frequency method) because of its advantages is widely used in actual production. However, as rock, ore, induced polarization effects are very complex and affected by many factors, the current induced polarization effects very di±cult to achieve an accurate description. Therefore, interpretation of induced polarization method in data analysis problems. In the application subject to certain restrictions. Cole-Cole model is used to describe the formula-mediated electric polarization in the form of complex resistivity and induced polarization equation in the form of the same frequency charac- teristics. The use of Cole-Cole model to be more a description of the image of rock, ore, induced polarization phenomenon, as the basis of the frequency-domain IP for effective forward modeling, can accurately describe the rock, ore characteristics of the induced polarization effects, developed a suitable IP method forward simulation software.

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