用经典力学的方法 ,研究了三种不同类型的一维库仑三体模型在总能量大于零时 (e ,2e)电离截面与总能量的关系 .发现了不同的模型的 (e ,2e)电离截面有不同的阈值行为 ;即s波模型 ,共线e-Ze-和Ze-e-模型的 (e ,2e)电离截面在阈值附近分...用经典力学的方法 ,研究了三种不同类型的一维库仑三体模型在总能量大于零时 (e ,2e)电离截面与总能量的关系 .发现了不同的模型的 (e ,2e)电离截面有不同的阈值行为 ;即s波模型 ,共线e-Ze-和Ze-e-模型的 (e ,2e)电离截面在阈值附近分别遵守线性律 ,Wannier定律和平方根律 .还对所得数值结果作了理论分析 .展开更多
The assessment of rainfall-induced shallow landslide hazards is a significant issue in the Three Gorges Reservoir area in China due to the rapid development of land in the past two decades. In this study, a probabilis...The assessment of rainfall-induced shallow landslide hazards is a significant issue in the Three Gorges Reservoir area in China due to the rapid development of land in the past two decades. In this study, a probabilistic analysis method that combines TRIGRS and the point-estimate method for evaluating the hazards of shallow landslides have been proposed under the condition of rainfall over a large area. TRIGRS provides the transient infiltration model to analyze the pore water pressure during a rainfall. The point-estimate method is used to analyze the uncertainty of the soil parameters, which is performed in the geographic information system(GIS). In this paper, we use this method to evaluate the hazards of shallow landslides in Badong County,Three Gorges Reservoir, under two different types of rainfall intensity, and the results are compared with the field investigation. The results showed that the distribution of the hazard map is consistent with the observed landslides. To some extent, the distributionof the hazard map reflects the spatial and temporal distribution of the shallow landslide caused by rainfall.展开更多
To understand the potential impact of the Three Gorges Reservoir on the aquatic ecosystem after the damming of the Yangtze River,we studied the community composition and temporal abundance distribution of algae in two...To understand the potential impact of the Three Gorges Reservoir on the aquatic ecosystem after the damming of the Yangtze River,we studied the community composition and temporal abundance distribution of algae in two types of water bodies:a segment of the Jialing River near its confluence with the Yangtze River as an example of the river-lake type,and Shuanglong Lake in Chongqing as an example of the lake type.In total,107 species belonging to 58 genera of 7 phyla were identified in the study area of the Jialing River,dominated by three groups with 49.5% diatoms,29.0% chlorophytes,and 11.4% cyanobacteria in the community composition.There were 122 species belonging to 66 genera of 8 phyla in Shuanglong Lake,dominated by the same three groups with 19.7% diatoms,48.4% chlorophytes,and 22.2% cyanobacteria.The densities of total algae and individual dominant groups were all much higher in the lake.More species of diatoms were found in the river-lake segment;whereas more chlorophyte species and cyanobacteriaum species were in the lake.There were 17 dominant species including 8 diatoms,4 chlorophytes,3 cyanobacteria and 2 cryptophytes in the river-lake segment,and 21 species in the lake,including 2 diatoms,9 chlorophytes,6 cyanobacteria,3 cryptophytes and a dinoflagellate.In eutrophic conditions,chlorophytes and cyanobacteria may proliferate in a lake-type area and diatoms may cause algal bloom in a relatively faster-flow lake-river type area.展开更多
The Taipei MRT (Metropolitan Rapid Transit) system has been operated since 1996. Facing the challenge of safety and sustainability of MRT, it is urgent to develop a structural inspection strategy and maintenance sys...The Taipei MRT (Metropolitan Rapid Transit) system has been operated since 1996. Facing the challenge of safety and sustainability of MRT, it is urgent to develop a structural inspection strategy and maintenance system based on the concept of life cycle management. In the mean while, BIM (Building Information Modeling) has become an emerging technology in the architecture and construction industries. BIM utilizes the 3D (3 Dimensions) CAD objects to simulate the real word building elements and with the ability to maintain life cycle information for a building. BIM is an ideal tool and platform for developing an inspection and maintenance system. The goal of this research is to establish a MRT structural inspection system concept based on BIM and life cycle management. In this study, a BIM model of shield tunnel was established to demonstrate the integration of 3D CAD with inspection records. A MRT structural maintenance database, which includes structural deterioration types, inspection records, and repair methods, was designed to interact with the BIM. An inspection prototype system was designed and implemented to perform the MRT structural inspection. The proposed system was designed with mobile-side and server-side systems. The mobile-side system was designed to perform on mobile devices such as tablet computer or smart phones with the ability to mark defects on BIM, as well as to fill in inspection sheets and photos; the server-side system can assign inspection tasks, maintains all inspection records, automatically output inspection reports, and analyze the database to prioritize all maintenance tasks.展开更多
The level-trench method is a traditional tillage operation to develop a drainage system on slope land in the Three Gorges region. Before crops are planted, farmers prepare the land with level trenches spaced 3-1o m ap...The level-trench method is a traditional tillage operation to develop a drainage system on slope land in the Three Gorges region. Before crops are planted, farmers prepare the land with level trenches spaced 3-1o m apart, depending on the slope gradient: steeper slopes require shorter distances. Little scientific analysis has been done on the use of traditional level trenches for soil conservation. We conducted a field investigation and simulation experiments, and present a comparison between the spacing of level trenches and the slope length required for rill initiation. The results indicate that the spacing of level trenches in farmland is close to the slope length required for rill initiation in the experimental plots, and regression models of trench spacing with the gradient and the slope length required for rill initiation with the gradient have similar formats; the coefficients of determination (R2) for the two equations are 0.99 and 0.88, respectively. There were some differences between the field survey and experiments, but we conclude that the traditional level-trench method has an important role in preventing rill initiation.展开更多
After the completion of the Three Gorges dam, a 30 m high water-level-fluctuating zone (WLFZ) will appear along the banks, and will form a seasonal wetland ecosystem. According to the program of storing water in the...After the completion of the Three Gorges dam, a 30 m high water-level-fluctuating zone (WLFZ) will appear along the banks, and will form a seasonal wetland ecosystem. According to the program of storing water in the Three Gorges reservoir, the main ecological and environmental problems probably incurred in WLFZ are discussed, such as formation of contaminated belt along banks, appearance of epidemic diseases in the reservoir region (including urban districts), aggravation of geologic disasters, degradation of biodiversity and exacerbation of the ecosystem vulnerability. Six items of strategies are put forward according to the causes, distributed features and trends of these problems in this paper.展开更多
To understand the responses of a freshwater ecosystem to the impoundment of the Three Gorges Reservoir (TGR), phytoplankton was monitored in the tributaries of the TGR area. From August 2010 to July 2011, algal spec...To understand the responses of a freshwater ecosystem to the impoundment of the Three Gorges Reservoir (TGR), phytoplankton was monitored in the tributaries of the TGR area. From August 2010 to July 2011, algal species composition, abundance, chlorophyll a and other environmental parameters were investigated in the Gaolan River, which is a tributary of Xiangxi River. Thirty-one algal genera from seven phyla were identified. Results show that the lowest concentrations of total phosphorus (TP) and total nitrogen (TN) were 0.06 mg/L and 1.08 rag/L, respectively. The values of TP and TN exceeded the threshold concentration of the eutrophic state suggested for freshwater bodies. In the Gaolan River, the succession of phytoplankton showed clear seasonal characteristics. Different dominant species were observed among seasons under the control of environment factors. In spring and summer, the dominant species were Nitzschia sp. and Aphanizomenon flos-aquae (L.) Ralfs, the limiting nutrient was NO3^--N, and the key environmental factor for phytoplankton population succession was water temperature (WT). In autumn and winter, the dominant species were A.flos-aquae and Chlorella sp., the limiting nutrient was pO3--P, and the key environmental factors were transparency and WT. This study illustrates the influence of physical and chemical factors on phytoplankton seasonal succession in a tributary of TGR since the downstream regions of Xiangxi River and Gaolan River became reservoirs after impoundment of the Three Gorges Dam. We suggest that this activity has significantly affected water quality in the dam area.展开更多
We describe the green space system planning and design of a new Kaixian City for migrants in the Three Gorges Reservoir area of P.R.China.The goal of the project was to provide a high quality settlement for migrants r...We describe the green space system planning and design of a new Kaixian City for migrants in the Three Gorges Reservoir area of P.R.China.The goal of the project was to provide a high quality settlement for migrants relocated from the old Kaixian City that had a history of over one thousand years and from other places with different traditional cultures.Our efforts focused on conceiving affordable strategies to increase green areas,improve waterfront landscapes,deal with water level fluctuation,integrate diverse folk cultures,and encourage bicycling as an environmentally-friendly form of urban transportation.The new city is anticipated to benefit from the green space systems with an improved eco-environment,enriched tourism resources,cheap landscaping costs,relief from traffic pressure,and in other ways.The planning philosophies employed could be useful in the engineering and construction of other cities in the Three Gorges Reservoir area.展开更多
文摘用经典力学的方法 ,研究了三种不同类型的一维库仑三体模型在总能量大于零时 (e ,2e)电离截面与总能量的关系 .发现了不同的模型的 (e ,2e)电离截面有不同的阈值行为 ;即s波模型 ,共线e-Ze-和Ze-e-模型的 (e ,2e)电离截面在阈值附近分别遵守线性律 ,Wannier定律和平方根律 .还对所得数值结果作了理论分析 .
基金The National Natural Science Foundation of China(SN:41572292)the follow-up work of geological disaster prevention projects in Three Gorges Reservoir supported the research in thispaper(SN:0001212015CC60005)
文摘The assessment of rainfall-induced shallow landslide hazards is a significant issue in the Three Gorges Reservoir area in China due to the rapid development of land in the past two decades. In this study, a probabilistic analysis method that combines TRIGRS and the point-estimate method for evaluating the hazards of shallow landslides have been proposed under the condition of rainfall over a large area. TRIGRS provides the transient infiltration model to analyze the pore water pressure during a rainfall. The point-estimate method is used to analyze the uncertainty of the soil parameters, which is performed in the geographic information system(GIS). In this paper, we use this method to evaluate the hazards of shallow landslides in Badong County,Three Gorges Reservoir, under two different types of rainfall intensity, and the results are compared with the field investigation. The results showed that the distribution of the hazard map is consistent with the observed landslides. To some extent, the distributionof the hazard map reflects the spatial and temporal distribution of the shallow landslide caused by rainfall.
基金Funded by the Natural Science Foundation of China (No.50178070)the Natural Science Foundation of Chongqing (Nos. 8091 and 7136)
文摘To understand the potential impact of the Three Gorges Reservoir on the aquatic ecosystem after the damming of the Yangtze River,we studied the community composition and temporal abundance distribution of algae in two types of water bodies:a segment of the Jialing River near its confluence with the Yangtze River as an example of the river-lake type,and Shuanglong Lake in Chongqing as an example of the lake type.In total,107 species belonging to 58 genera of 7 phyla were identified in the study area of the Jialing River,dominated by three groups with 49.5% diatoms,29.0% chlorophytes,and 11.4% cyanobacteria in the community composition.There were 122 species belonging to 66 genera of 8 phyla in Shuanglong Lake,dominated by the same three groups with 19.7% diatoms,48.4% chlorophytes,and 22.2% cyanobacteria.The densities of total algae and individual dominant groups were all much higher in the lake.More species of diatoms were found in the river-lake segment;whereas more chlorophyte species and cyanobacteriaum species were in the lake.There were 17 dominant species including 8 diatoms,4 chlorophytes,3 cyanobacteria and 2 cryptophytes in the river-lake segment,and 21 species in the lake,including 2 diatoms,9 chlorophytes,6 cyanobacteria,3 cryptophytes and a dinoflagellate.In eutrophic conditions,chlorophytes and cyanobacteria may proliferate in a lake-type area and diatoms may cause algal bloom in a relatively faster-flow lake-river type area.
文摘The Taipei MRT (Metropolitan Rapid Transit) system has been operated since 1996. Facing the challenge of safety and sustainability of MRT, it is urgent to develop a structural inspection strategy and maintenance system based on the concept of life cycle management. In the mean while, BIM (Building Information Modeling) has become an emerging technology in the architecture and construction industries. BIM utilizes the 3D (3 Dimensions) CAD objects to simulate the real word building elements and with the ability to maintain life cycle information for a building. BIM is an ideal tool and platform for developing an inspection and maintenance system. The goal of this research is to establish a MRT structural inspection system concept based on BIM and life cycle management. In this study, a BIM model of shield tunnel was established to demonstrate the integration of 3D CAD with inspection records. A MRT structural maintenance database, which includes structural deterioration types, inspection records, and repair methods, was designed to interact with the BIM. An inspection prototype system was designed and implemented to perform the MRT structural inspection. The proposed system was designed with mobile-side and server-side systems. The mobile-side system was designed to perform on mobile devices such as tablet computer or smart phones with the ability to mark defects on BIM, as well as to fill in inspection sheets and photos; the server-side system can assign inspection tasks, maintains all inspection records, automatically output inspection reports, and analyze the database to prioritize all maintenance tasks.
基金supported by the Ministry of Science and Technology of China (Grant No.2011BAD31B03)the Ministry of Environment of China (Grant No.2009ZX07104-002-06)
文摘The level-trench method is a traditional tillage operation to develop a drainage system on slope land in the Three Gorges region. Before crops are planted, farmers prepare the land with level trenches spaced 3-1o m apart, depending on the slope gradient: steeper slopes require shorter distances. Little scientific analysis has been done on the use of traditional level trenches for soil conservation. We conducted a field investigation and simulation experiments, and present a comparison between the spacing of level trenches and the slope length required for rill initiation. The results indicate that the spacing of level trenches in farmland is close to the slope length required for rill initiation in the experimental plots, and regression models of trench spacing with the gradient and the slope length required for rill initiation with the gradient have similar formats; the coefficients of determination (R2) for the two equations are 0.99 and 0.88, respectively. There were some differences between the field survey and experiments, but we conclude that the traditional level-trench method has an important role in preventing rill initiation.
基金Thanks the financial support from National Natural Science Foundation of China (#40561006), National Natural Science Foundation of China (06XYJ017), and Key Foundation of Chongqing Normal University (08XLZ13).
文摘After the completion of the Three Gorges dam, a 30 m high water-level-fluctuating zone (WLFZ) will appear along the banks, and will form a seasonal wetland ecosystem. According to the program of storing water in the Three Gorges reservoir, the main ecological and environmental problems probably incurred in WLFZ are discussed, such as formation of contaminated belt along banks, appearance of epidemic diseases in the reservoir region (including urban districts), aggravation of geologic disasters, degradation of biodiversity and exacerbation of the ecosystem vulnerability. Six items of strategies are put forward according to the causes, distributed features and trends of these problems in this paper.
基金Supported by the National Major Programs of Water Body Pollution Control and Remediation(No.2012ZX07103003-02)the National Basic Research Program of China(973 Program)(No.2008CB418000)
文摘To understand the responses of a freshwater ecosystem to the impoundment of the Three Gorges Reservoir (TGR), phytoplankton was monitored in the tributaries of the TGR area. From August 2010 to July 2011, algal species composition, abundance, chlorophyll a and other environmental parameters were investigated in the Gaolan River, which is a tributary of Xiangxi River. Thirty-one algal genera from seven phyla were identified. Results show that the lowest concentrations of total phosphorus (TP) and total nitrogen (TN) were 0.06 mg/L and 1.08 rag/L, respectively. The values of TP and TN exceeded the threshold concentration of the eutrophic state suggested for freshwater bodies. In the Gaolan River, the succession of phytoplankton showed clear seasonal characteristics. Different dominant species were observed among seasons under the control of environment factors. In spring and summer, the dominant species were Nitzschia sp. and Aphanizomenon flos-aquae (L.) Ralfs, the limiting nutrient was NO3^--N, and the key environmental factor for phytoplankton population succession was water temperature (WT). In autumn and winter, the dominant species were A.flos-aquae and Chlorella sp., the limiting nutrient was pO3--P, and the key environmental factors were transparency and WT. This study illustrates the influence of physical and chemical factors on phytoplankton seasonal succession in a tributary of TGR since the downstream regions of Xiangxi River and Gaolan River became reservoirs after impoundment of the Three Gorges Dam. We suggest that this activity has significantly affected water quality in the dam area.
文摘We describe the green space system planning and design of a new Kaixian City for migrants in the Three Gorges Reservoir area of P.R.China.The goal of the project was to provide a high quality settlement for migrants relocated from the old Kaixian City that had a history of over one thousand years and from other places with different traditional cultures.Our efforts focused on conceiving affordable strategies to increase green areas,improve waterfront landscapes,deal with water level fluctuation,integrate diverse folk cultures,and encourage bicycling as an environmentally-friendly form of urban transportation.The new city is anticipated to benefit from the green space systems with an improved eco-environment,enriched tourism resources,cheap landscaping costs,relief from traffic pressure,and in other ways.The planning philosophies employed could be useful in the engineering and construction of other cities in the Three Gorges Reservoir area.