Compared with other migration methods, reverse-time migration is based on a precise wave equation, not an approximation, and performs extrapolation in the depth domain rather than the time domain. It is highly accurat...Compared with other migration methods, reverse-time migration is based on a precise wave equation, not an approximation, and performs extrapolation in the depth domain rather than the time domain. It is highly accurate and not affected by strong subsurface structure complexity and horizontal velocity variations. The difference method based on triangular grids maintains the simplicity of the difference method and the precision of the finite element method. It can be used directly for forward modeling on models with complex top surfaces and migration without statics preprocessing. We apply a finite difference method based on triangular grids for post-stack reverse-time migration for the first time. Tests on model data verify that the combination of the two methods can achieve near-perfect results in application.展开更多
Structured packing is a good candidate for CO2 capture process because of its higher mass transfer efficiency and lower pressure drop. Now, the challenging problem of CO2 capture and storage demands more and more effi...Structured packing is a good candidate for CO2 capture process because of its higher mass transfer efficiency and lower pressure drop. Now, the challenging problem of CO2 capture and storage demands more and more efficiency equipment. The aim of the present study is to investigate the liquid film characteristics under counter current gas phase and throw some insight into the enhancing mechanism of mass transfer performance in structured packing. A high speed digital camera, non-intrusive measurement technique, was used. Water and air were working fluids. Experiments were carried out for different gas/liquid flow rates and different inclination angles. The time-average and instantaneous film widths for each set of flow parameters were calculated. It is shown that the effects of gas phase could be neglected for lower flow rate, and then, become more pronounced at higher flow rate. According to instantaneous film width, three different stages can be distinguished. One is the constant width of liquid film. The second is the slight decrease of film width and the smooth surface. This kind of character will lead to less interfacial area and deteriorate the packing mass transfer performance. For the third stage, the variation of film width shows clearly chaotic behavior. The prediction model was also developed in present work. The predicted and experimental results are in good agreement.展开更多
During the storehouse surface rolling construction of a core rockfilldam, the spreading thickness of dam face is an important factor that affects the construction quality of the dam storehouse' rolling surface and...During the storehouse surface rolling construction of a core rockfilldam, the spreading thickness of dam face is an important factor that affects the construction quality of the dam storehouse' rolling surface and the overallquality of the entire dam. Currently, the method used to monitor and controlspreading thickness during the dam construction process is artificialsampling check after spreading, which makes it difficult to monitor the entire dam storehouse surface. In this paper, we present an in-depth study based on real-time monitoring and controltheory of storehouse surface rolling construction and obtain the rolling compaction thickness by analyzing the construction track of the rolling machine. Comparatively, the traditionalmethod can only analyze the rolling thickness of the dam storehouse surface after it has been compacted and cannot determine the thickness of the dam storehouse surface in realtime. To solve these problems, our system monitors the construction progress of the leveling machine and employs a real-time spreading thickness monitoring modelbased on the K-nearest neighbor algorithm. Taking the LHK core rockfilldam in Southwest China as an example, we performed real-time monitoring for the spreading thickness and conducted real-time interactive queries regarding the spreading thickness. This approach provides a new method for controlling the spreading thickness of the core rockfilldam storehouse surface.展开更多
Symbiotic algae from two anemones, Radianthus macrodactylus and Stichodactyla mertensii, found in the South China Sea, were cultivated in ASP-8A medium in this study. Changes of superficial configuration of symbiotic ...Symbiotic algae from two anemones, Radianthus macrodactylus and Stichodactyla mertensii, found in the South China Sea, were cultivated in ASP-8A medium in this study. Changes of superficial configuration of symbiotic algae during the cultivation were studied by means of a microscope and a scanning electron microscope (SEM). A number of small cavities appeared on the sur- faces of symbiotic algae after they were cultivated for 10 h. The cavities enlarged and the cell contents were lost with extended culti- vation. Our data suggested that the presence of cavities on symbiotic algae surfaces may be one of the main reasons for failure to culture symbiotic algae in an artificial medium.展开更多
Nowadays orthogonal arrays play important roles in statistics, computer science, coding theory and cryptography. The usual difference matrices are essential for the construction of many mixed orthogonal arrays. But th...Nowadays orthogonal arrays play important roles in statistics, computer science, coding theory and cryptography. The usual difference matrices are essential for the construction of many mixed orthogonal arrays. But there are also many orthogonal arrays, especially mixed-level or asymmetrical which can not be obtained by the usual difference matrices. In order to construct these asymmetrical orthogonal arrays, a class of special matrices, so-called generalized difference matrices, were discovered by Zhang（1989, 1990, 1993） by the orthogonal decompositions of projective matrices. In this article, an interesting equivalent relationship between the orthogonal arrays and the generalized difference matrices is presented. As an application, a family of orthogonal arrays of run sizes 4p2, such as L36（6^13^42^10）, are constructed.展开更多
When mining metal mines with steep structure planes by the caving method,there is a mechanical model in which the horizontal stress on the rock mass is simplified as a column before surface subsidence.The model is use...When mining metal mines with steep structure planes by the caving method,there is a mechanical model in which the horizontal stress on the rock mass is simplified as a column before surface subsidence.The model is used to deduce critical support load and limiting column length for a given horizontal stress and support pressure.Considering the impact of the column effect,a method is proposed to determine the movement of the ground and caving area in a mine.After surface subsidence,the horizontal stress on a surrounding rock mass can be simplified to a cantilever beam mechanical model.Expressions for its bending fracture length are deduced,and a method is given to determine its stability.On this basis,an explanation for the large ground movement and subsidence scope was given.A case study shows that the damage effect of column and cantilever beam is significant for ground movement in metal-ore mine,and an appropriate correction value should be applied when designing for its angle of ground movements.展开更多
The reconstructed structures of Cu（100） surface induced by O2 dissociative adsorption were investigated by low energy electron diffraction and scanning tunneling microscopy. At lower oxygen coverage, it was found th...The reconstructed structures of Cu（100） surface induced by O2 dissociative adsorption were investigated by low energy electron diffraction and scanning tunneling microscopy. At lower oxygen coverage, it was found that two reconstructed structures, i.e. c（2×2）-O and （√2×2√2）R45°-O are coexistent. The domain size of the c（2×2）-O structure decreased with the increasing of O2 exposure. The reconstructed structure at very small coverage was also investigated and a “zigzag” structure was observed at this stage. The “zigzag” structure was identified as boundaries of local c（2×2） domains. It was found that the strip region shows much stronger molecule-substrate interaction than that of oxygen covered regions, making it a proper template for patterned organic films. The sequence of the thermal stability was found as zigzag structure〉c（2×2）〉（√2×2√2）R45°-O.展开更多
Fractal geometry is increasingly becoming a useful tool for modeling and quantifying the complex patterns of natural phenomena. The Earth's topography is one of these phenomena that have fractal characteristics. T...Fractal geometry is increasingly becoming a useful tool for modeling and quantifying the complex patterns of natural phenomena. The Earth's topography is one of these phenomena that have fractal characteristics. This paper investigates the relative sensitivity of topography to active tectonics using ASTER Global Digital Elevation Model. The covering divider method was used for direct extraction of surface fractal dimension(D surf) to estimate the roughness-surface of topography with aid of geographic information system(GIS)techniques. This evaluation let us highlight the role of the geomorphic and tectonic processes on the spatial variability of fractal properties of natural landforms.Geomorphic zones can be delineated using fractal dimension mapping in which variability of surface fractal dimension reflects the roughness of the landform surface and is a measure of topography texture. Obtained results showed this method can be a quick and easy way to assess the distribution of land surface deformation in different tectonic settings. The loose alluvial deposits and irregularities derived by tectonic activity have high fractal dimensions whereas the competent formations and higher wavelength folded surfaces have lower fractal dimensions.According to the obtained results, the Kazerun Fault Zone has a crucial role in the separation of the Zagros Mountain Ranges into the different lithological,geomorphological and structural zones.展开更多
The fields of structural geology and tectonics have witnessed great progress over the last decade and are poised for further expansion in the future. One of the significant breakthroughs is the establishment of the &#...The fields of structural geology and tectonics have witnessed great progress over the last decade and are poised for further expansion in the future. One of the significant breakthroughs is the establishment of the 'Beyond Plate Tectonics Theory' where a combination of conceptual models and numerical modeling on plume tectonics and plate tectonics has enabled new insights into the structural and tectonic architecture and processes in the deep interior and deep sea. This paper synthesizes developments of structural geology and tectonics from a macroscopic perspective in deep interior and deep sea. Four key techniques are also reviewed: satellite altimetry for surface structures in deep-sea multi-beam sea-floor mapping; tomography for tectonics of the deep interior; diverse modeling approaches and software for unfolding dynamic evolution; and techniques for HT/HP experiments on material rheology and in situ component measurements.展开更多
Using the seismic method to detect active faults directly below cities is an irreplaceable prospecting technique. The seismic method can precisely determine the fault position. Seismic method itself can hardly determi...Using the seismic method to detect active faults directly below cities is an irreplaceable prospecting technique. The seismic method can precisely determine the fault position. Seismic method itself can hardly determine the geological age of fault. However, by considering in connection with the borehole data and the standard geological cross-section of the surveyed area, the geological age of reflected wave group can be qualitatively (or semi-quantitatively) determined from the seismic depth profile. To determine the upper terminal point of active faults directly below city, it is necessary to use the high-resolution seismic reflection technique. To effectively determine the geometric feature of deep faults, especially to determine the relation between deep and shallow fracture structures, the seismic reflection method is better than the seismic refraction method.展开更多
基金sponsored by National Natural Science Foundation(40474041)National Symposium of 863(2006AA06Z206)+1 种基金National Symposium of 973(2007CB209605)CNPC Geophysical Key Laboratory of the China University of Petroleum (East China) Research Department
文摘Compared with other migration methods, reverse-time migration is based on a precise wave equation, not an approximation, and performs extrapolation in the depth domain rather than the time domain. It is highly accurate and not affected by strong subsurface structure complexity and horizontal velocity variations. The difference method based on triangular grids maintains the simplicity of the difference method and the precision of the finite element method. It can be used directly for forward modeling on models with complex top surfaces and migration without statics preprocessing. We apply a finite difference method based on triangular grids for post-stack reverse-time migration for the first time. Tests on model data verify that the combination of the two methods can achieve near-perfect results in application.
基金Supported by the National Natural Science Foundation of China （20070003154）, the National High Technology Research and Development Program of China （2006AA05Z316, 2006AA030202）, the Specialized Research Fund for Doctoral Program of Higher Education of China （20070003154）, and the Key Program for International Cooperation of Science and Technology, China （2001CB711203）.
文摘Structured packing is a good candidate for CO2 capture process because of its higher mass transfer efficiency and lower pressure drop. Now, the challenging problem of CO2 capture and storage demands more and more efficiency equipment. The aim of the present study is to investigate the liquid film characteristics under counter current gas phase and throw some insight into the enhancing mechanism of mass transfer performance in structured packing. A high speed digital camera, non-intrusive measurement technique, was used. Water and air were working fluids. Experiments were carried out for different gas/liquid flow rates and different inclination angles. The time-average and instantaneous film widths for each set of flow parameters were calculated. It is shown that the effects of gas phase could be neglected for lower flow rate, and then, become more pronounced at higher flow rate. According to instantaneous film width, three different stages can be distinguished. One is the constant width of liquid film. The second is the slight decrease of film width and the smooth surface. This kind of character will lead to less interfacial area and deteriorate the packing mass transfer performance. For the third stage, the variation of film width shows clearly chaotic behavior. The prediction model was also developed in present work. The predicted and experimental results are in good agreement.
基金supported by the Innovative Research Groups of National Natural Science Foundation of China(No. 51621092)National Basic Research Program of China ("973" Program, No. 2013CB035904)National Natural Science Foundation of China (No. 51439005)
文摘During the storehouse surface rolling construction of a core rockfilldam, the spreading thickness of dam face is an important factor that affects the construction quality of the dam storehouse' rolling surface and the overallquality of the entire dam. Currently, the method used to monitor and controlspreading thickness during the dam construction process is artificialsampling check after spreading, which makes it difficult to monitor the entire dam storehouse surface. In this paper, we present an in-depth study based on real-time monitoring and controltheory of storehouse surface rolling construction and obtain the rolling compaction thickness by analyzing the construction track of the rolling machine. Comparatively, the traditionalmethod can only analyze the rolling thickness of the dam storehouse surface after it has been compacted and cannot determine the thickness of the dam storehouse surface in realtime. To solve these problems, our system monitors the construction progress of the leveling machine and employs a real-time spreading thickness monitoring modelbased on the K-nearest neighbor algorithm. Taking the LHK core rockfilldam in Southwest China as an example, we performed real-time monitoring for the spreading thickness and conducted real-time interactive queries regarding the spreading thickness. This approach provides a new method for controlling the spreading thickness of the core rockfilldam storehouse surface.
基金supported by the National Natural Science Foundation of China(Grant No.U0633006)Project for Supporting the National Development(No.2006BAD09A04)the 863 Project of China(Grant Nos.2006AA05Z112 and 2006AA10A413).
文摘Symbiotic algae from two anemones, Radianthus macrodactylus and Stichodactyla mertensii, found in the South China Sea, were cultivated in ASP-8A medium in this study. Changes of superficial configuration of symbiotic algae during the cultivation were studied by means of a microscope and a scanning electron microscope (SEM). A number of small cavities appeared on the sur- faces of symbiotic algae after they were cultivated for 10 h. The cavities enlarged and the cell contents were lost with extended culti- vation. Our data suggested that the presence of cavities on symbiotic algae surfaces may be one of the main reasons for failure to culture symbiotic algae in an artificial medium.
基金the National Science Foundations of China(10571045)the National Science Foundations of Henan Province(02243700510211063100)
文摘Nowadays orthogonal arrays play important roles in statistics, computer science, coding theory and cryptography. The usual difference matrices are essential for the construction of many mixed orthogonal arrays. But there are also many orthogonal arrays, especially mixed-level or asymmetrical which can not be obtained by the usual difference matrices. In order to construct these asymmetrical orthogonal arrays, a class of special matrices, so-called generalized difference matrices, were discovered by Zhang（1989, 1990, 1993） by the orthogonal decompositions of projective matrices. In this article, an interesting equivalent relationship between the orthogonal arrays and the generalized difference matrices is presented. As an application, a family of orthogonal arrays of run sizes 4p2, such as L36（6^13^42^10）, are constructed.
基金Project(51274188)supported by the National Natural Science Foundation of China
文摘When mining metal mines with steep structure planes by the caving method,there is a mechanical model in which the horizontal stress on the rock mass is simplified as a column before surface subsidence.The model is used to deduce critical support load and limiting column length for a given horizontal stress and support pressure.Considering the impact of the column effect,a method is proposed to determine the movement of the ground and caving area in a mine.After surface subsidence,the horizontal stress on a surrounding rock mass can be simplified to a cantilever beam mechanical model.Expressions for its bending fracture length are deduced,and a method is given to determine its stability.On this basis,an explanation for the large ground movement and subsidence scope was given.A case study shows that the damage effect of column and cantilever beam is significant for ground movement in metal-ore mine,and an appropriate correction value should be applied when designing for its angle of ground movements.
基金ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China （No.60506019）.
文摘The reconstructed structures of Cu（100） surface induced by O2 dissociative adsorption were investigated by low energy electron diffraction and scanning tunneling microscopy. At lower oxygen coverage, it was found that two reconstructed structures, i.e. c（2×2）-O and （√2×2√2）R45°-O are coexistent. The domain size of the c（2×2）-O structure decreased with the increasing of O2 exposure. The reconstructed structure at very small coverage was also investigated and a “zigzag” structure was observed at this stage. The “zigzag” structure was identified as boundaries of local c（2×2） domains. It was found that the strip region shows much stronger molecule-substrate interaction than that of oxygen covered regions, making it a proper template for patterned organic films. The sequence of the thermal stability was found as zigzag structure〉c（2×2）〉（√2×2√2）R45°-O.
基金the Research Council of Shiraz University which has supported the project
文摘Fractal geometry is increasingly becoming a useful tool for modeling and quantifying the complex patterns of natural phenomena. The Earth's topography is one of these phenomena that have fractal characteristics. This paper investigates the relative sensitivity of topography to active tectonics using ASTER Global Digital Elevation Model. The covering divider method was used for direct extraction of surface fractal dimension(D surf) to estimate the roughness-surface of topography with aid of geographic information system(GIS)techniques. This evaluation let us highlight the role of the geomorphic and tectonic processes on the spatial variability of fractal properties of natural landforms.Geomorphic zones can be delineated using fractal dimension mapping in which variability of surface fractal dimension reflects the roughness of the landform surface and is a measure of topography texture. Obtained results showed this method can be a quick and easy way to assess the distribution of land surface deformation in different tectonic settings. The loose alluvial deposits and irregularities derived by tectonic activity have high fractal dimensions whereas the competent formations and higher wavelength folded surfaces have lower fractal dimensions.According to the obtained results, the Kazerun Fault Zone has a crucial role in the separation of the Zagros Mountain Ranges into the different lithological,geomorphological and structural zones.
基金Funding Sources:Marine 863 Project (No.2009AA093401)Projects of the National Natural Science Foundation of China (Nos.41072152,90814011 and 41190072)
文摘The fields of structural geology and tectonics have witnessed great progress over the last decade and are poised for further expansion in the future. One of the significant breakthroughs is the establishment of the 'Beyond Plate Tectonics Theory' where a combination of conceptual models and numerical modeling on plume tectonics and plate tectonics has enabled new insights into the structural and tectonic architecture and processes in the deep interior and deep sea. This paper synthesizes developments of structural geology and tectonics from a macroscopic perspective in deep interior and deep sea. Four key techniques are also reviewed: satellite altimetry for surface structures in deep-sea multi-beam sea-floor mapping; tomography for tectonics of the deep interior; diverse modeling approaches and software for unfolding dynamic evolution; and techniques for HT/HP experiments on material rheology and in situ component measurements.
文摘Using the seismic method to detect active faults directly below cities is an irreplaceable prospecting technique. The seismic method can precisely determine the fault position. Seismic method itself can hardly determine the geological age of fault. However, by considering in connection with the borehole data and the standard geological cross-section of the surveyed area, the geological age of reflected wave group can be qualitatively (or semi-quantitatively) determined from the seismic depth profile. To determine the upper terminal point of active faults directly below city, it is necessary to use the high-resolution seismic reflection technique. To effectively determine the geometric feature of deep faults, especially to determine the relation between deep and shallow fracture structures, the seismic reflection method is better than the seismic refraction method.
