The Baiyun sag is a deep one developing on the slope of the Pearl River Mouth Basin. It occurs as a composite graben horizontally, and is composed of two sub-sags versus one low uplift. Vertically, the sedimentary arc...The Baiyun sag is a deep one developing on the slope of the Pearl River Mouth Basin. It occurs as a composite graben horizontally, and is composed of two sub-sags versus one low uplift. Vertically, the sedimentary architecture could be divided into three layers, i.e. the faulted layer on the bottom, the faulted-ductile stretching layer in the middle and the draping layer on the top. The main rifting stage of the sag is supposed to be characterized by ductile extension and thinning of the crust. The special deformation pattern is probably attributed to the fact that the Baiyun sag is located in the transfer zone of the pre-existing weak zone, which made the sag a strongly deformed area, characterized by the greatly thinned lithosphere and active magmatism. The highly rising mantle under the Baiyun sag should be an important mechanism responsible for the ductile deformation, which caused partial melting of the upper mantle. Upweiling to the upper crust and the sedimentary layers, the partial melting materials accommodated extensional strain and caused non-faulted vertical subsidence. Magma was collected under the transfer zone after the first stage of rifting, and transferred laterally in a direction perpendicular to the extension to the ENE and WSW parts of the sag and upwelled along the NW-trending basal faults, where WNW-trending shear faults developed in swarms. The faulting activity and sedimentation history of the Baiyun sag may have been affected by the ocean ridge jump around 24 Ma and the cessation of sea floor spreading around 16 Ma.展开更多
New acquired and reprocessed three-dimensional(3D)seismic data were used to delineate the distribution and characterization of bottom simulating reflections(BSRs)in the Chaoshan Sag,in the eastern part of Dongsha Isla...New acquired and reprocessed three-dimensional(3D)seismic data were used to delineate the distribution and characterization of bottom simulating reflections(BSRs)in the Chaoshan Sag,in the eastern part of Dongsha Island,South China Sea.Three submarine canyons with different scales were interpreted from the 3D seismic data,displaying three stages of canyon development and are related with the variation of BSR.Abundant faults were identified from the coherence and ant-tracing attributions extracted from 3D seismic data,which provide the evidence for fluid migration from deeper sediments to the gas hydrate stability zone(GHSZ).The uplift of Dongsha Island created a large number of faults and leads to the increased seafloor erosion.The erosion caused the cooling of the seafloor sediments and deepening of the base of the gas hydrate stability zone,which is attributed to the presence of paleo-BSR and BSR downward shift in the study area.Hence,methane gas may be released during the BSR resetting and gas hydrate dissociation related with seafloor erosion.展开更多
The alpine wetlands in QTP(Qinghai-Tibetan Plateau)have been profoundly impacted along with global climate changes.We employ satellite datasets and climate data to explore the relationships between alpine wetlands and...The alpine wetlands in QTP(Qinghai-Tibetan Plateau)have been profoundly impacted along with global climate changes.We employ satellite datasets and climate data to explore the relationships between alpine wetlands and climate changes based on remote sensing data.Results show that:1)the wetland NDVI(Normalized Difference Vegetation Index)and GPP(Gross Primary Production)were more sensitive to air temperature than to precipitation rate.The wetland ET(evapotranspiration)across alpine wetlands was greatly correlated with precipitation rate.2)Alpine wetlands responses to climate changes varied spatially and temporally due to different geographic environments,variety of wetland formation and human disturbances.3)The vegetation responses of the Zoige wetland was the most noticeable and related to the temperature,while the GPP and NDVI of the Qiangtang Plateau and Gyaring-Ngoring Lake were significantly correlated with both temperature and precipitation.4)ET in the Zoige wetland showed a significantly positive trend,while ET in Maidika wetland and the Qiangtang plateau showed a negative trend,implying wetland degradation in those two wetland regions.The complexities of the impacts of climate changes on alpine wetlands indicate the necessity of further study to understand and conserve alpine wetland ecosystems.展开更多
Investigation of phosphorus (P) sorption-desorption characteristics of drainage ditch sediments is important for better understanding on sediment P transport behaviors in ditches. Surface ditch sediment samples were c...Investigation of phosphorus (P) sorption-desorption characteristics of drainage ditch sediments is important for better understanding on sediment P transport behaviors in ditches. Surface ditch sediment samples were collected from headwater sub-catchment of forestland, sloping cropland, paddy field, and residential area in a representative catchment in the central Sichuan Basin. These sediment samples were used for determination of P sorption-desorption characteristics by a batch equilibrium technique. Results showed that the maximum P sorption capacities (Qm) in the sediments ranged from 159.7 to 263.7 mg/kg, while higher Qm were observed in the ditch sediments from the paddy fields. The Qm was significantly and positively correlated with oxalate-extractable Fe and Al oxides (r=0.97 and 0.98, p < 0.01), clay fraction (r = 0.78, p < 0.05) and organic matter (r = 0.95, p < 0.01). Sediment pH, clay and organic matter influenced the P sorption through amorphous Fe and Al oxides. CaCO3 content was negatively correlated with the Qm (r = -0.83, p < 0.05), implying that saturated CaCO3 (> 50 g/kg) would not increase P sorption capacity in the ditch sediments. The ditch sediments featured a linear desorption curve, suggesting that P release risk would be enhanced with the increase of the P adsorption. The P desorption rate was positively correlated with Olsen P (r = 0.94, p < 0.01), but negatively related to the fine particle-size fractions (r = -0.92, p < 0.01), the sum of the amorphous Fe and Al oxides (r = -0.67, p < 0.05) and the P sorption capacity (r = -0.59, p < 0.05). The ditch sediments from residential area had a higher P release risk than that from the other ditches of forestland, sloping cropland and paddy field. The P sorption index (PSI) derived from single-point measurement was significantly correlated with the P sorption capacity (r = 0.99, p < 0.01), and could be used for estimating Qm as 1.64 times PSI plus 24.0 (Qm = 1.64 PSI + 24.0) for similar sediments with highly calcareous soils and sediments. Ditch cleaning and sediment removal for the ditch in residential area were recommended in this area to reduce the P release risk.展开更多
Graphite antimony composites were prepared using a mechanical pressure infiltration method to force molten antimony into graphite preforms having a percolation micro-structure and a hop-pocket power filler. The micro-...Graphite antimony composites were prepared using a mechanical pressure infiltration method to force molten antimony into graphite preforms having a percolation micro-structure and a hop-pocket power filler. The micro-structural and macroscopic properties of the graphite antimony composites were analysed. Observations included metallographic analysis, physical properties and friction and wear behaviour. The results show that the wear loss is decreased by 12.24% and that the friction coefficient is re-duced by 32.61% after hop-pocket power was used. The research indicates that the hop-pocket power method gives a useful way to reduce friction coefficients and wear loss, and to increase service life and self-lubrication properties, of the graphite antimony seal-ing material as compared to carbon black.展开更多
在全面推广高速公路差异化收费背景下,针对如何选取差异化收费路段的问题,建立一种基于多源数据的差异化收费路段识别方法.首先,基于高速公路门架数据、收费站出入口流量、普通国省道交通流量自动观测站数据等多源数据,从路段沿线社会...在全面推广高速公路差异化收费背景下,针对如何选取差异化收费路段的问题,建立一种基于多源数据的差异化收费路段识别方法.首先,基于高速公路门架数据、收费站出入口流量、普通国省道交通流量自动观测站数据等多源数据,从路段沿线社会经济发展水平、网络化水平、交通运行特征、交通可转移性、交通负荷均衡性5个维度,构建高速公路差异化收费路段识别指标体系.然后,基于k-means聚类和分类回归树算法(Classification and Regression Trees,CART)建立高速公路差异化收费路段识别模型.最后,以云南省130条高速公路路段为例,提取高速公路差异化收费路段细分规则及关键特征指标.研究结果表明:影响高速公路差异化收费路段细分的关键特征指标分别为路段成网率、收费站节点度、出行成本偏差率、路段全天小时拥挤度、可替代路径数量;根据决策树细分规则可将差异化收费路段划分为差异化上浮型、不适合差异化、差异化下浮型3种,符合高速公路实际收费运营情况.展开更多
文摘The Baiyun sag is a deep one developing on the slope of the Pearl River Mouth Basin. It occurs as a composite graben horizontally, and is composed of two sub-sags versus one low uplift. Vertically, the sedimentary architecture could be divided into three layers, i.e. the faulted layer on the bottom, the faulted-ductile stretching layer in the middle and the draping layer on the top. The main rifting stage of the sag is supposed to be characterized by ductile extension and thinning of the crust. The special deformation pattern is probably attributed to the fact that the Baiyun sag is located in the transfer zone of the pre-existing weak zone, which made the sag a strongly deformed area, characterized by the greatly thinned lithosphere and active magmatism. The highly rising mantle under the Baiyun sag should be an important mechanism responsible for the ductile deformation, which caused partial melting of the upper mantle. Upweiling to the upper crust and the sedimentary layers, the partial melting materials accommodated extensional strain and caused non-faulted vertical subsidence. Magma was collected under the transfer zone after the first stage of rifting, and transferred laterally in a direction perpendicular to the extension to the ENE and WSW parts of the sag and upwelled along the NW-trending basal faults, where WNW-trending shear faults developed in swarms. The faulting activity and sedimentation history of the Baiyun sag may have been affected by the ocean ridge jump around 24 Ma and the cessation of sea floor spreading around 16 Ma.
基金the National Key R&D Program of China(No.2017YFC0307301-1)the National Natural Science Foundation of China(No.41676041)+1 种基金the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.GML2019ZD0104)the National High Technology Research and Development Program of China(863 Program)(No.2013AA092601)。
文摘New acquired and reprocessed three-dimensional(3D)seismic data were used to delineate the distribution and characterization of bottom simulating reflections(BSRs)in the Chaoshan Sag,in the eastern part of Dongsha Island,South China Sea.Three submarine canyons with different scales were interpreted from the 3D seismic data,displaying three stages of canyon development and are related with the variation of BSR.Abundant faults were identified from the coherence and ant-tracing attributions extracted from 3D seismic data,which provide the evidence for fluid migration from deeper sediments to the gas hydrate stability zone(GHSZ).The uplift of Dongsha Island created a large number of faults and leads to the increased seafloor erosion.The erosion caused the cooling of the seafloor sediments and deepening of the base of the gas hydrate stability zone,which is attributed to the presence of paleo-BSR and BSR downward shift in the study area.Hence,methane gas may be released during the BSR resetting and gas hydrate dissociation related with seafloor erosion.
基金Under the auspices of the National Key R&D Program of China(No.2017YFA0603004)Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA19030203)National Natural Science Foundation of China(No.41971390).
文摘The alpine wetlands in QTP(Qinghai-Tibetan Plateau)have been profoundly impacted along with global climate changes.We employ satellite datasets and climate data to explore the relationships between alpine wetlands and climate changes based on remote sensing data.Results show that:1)the wetland NDVI(Normalized Difference Vegetation Index)and GPP(Gross Primary Production)were more sensitive to air temperature than to precipitation rate.The wetland ET(evapotranspiration)across alpine wetlands was greatly correlated with precipitation rate.2)Alpine wetlands responses to climate changes varied spatially and temporally due to different geographic environments,variety of wetland formation and human disturbances.3)The vegetation responses of the Zoige wetland was the most noticeable and related to the temperature,while the GPP and NDVI of the Qiangtang Plateau and Gyaring-Ngoring Lake were significantly correlated with both temperature and precipitation.4)ET in the Zoige wetland showed a significantly positive trend,while ET in Maidika wetland and the Qiangtang plateau showed a negative trend,implying wetland degradation in those two wetland regions.The complexities of the impacts of climate changes on alpine wetlands indicate the necessity of further study to understand and conserve alpine wetland ecosystems.
基金supported jointly by the CAS Action Plan for the Development of Western China (Grant No. KZCX2-XB3-09)the Key Project in the National Science and Technology Pillar Program of China (Grant No. 2011BAD31B03)
文摘Investigation of phosphorus (P) sorption-desorption characteristics of drainage ditch sediments is important for better understanding on sediment P transport behaviors in ditches. Surface ditch sediment samples were collected from headwater sub-catchment of forestland, sloping cropland, paddy field, and residential area in a representative catchment in the central Sichuan Basin. These sediment samples were used for determination of P sorption-desorption characteristics by a batch equilibrium technique. Results showed that the maximum P sorption capacities (Qm) in the sediments ranged from 159.7 to 263.7 mg/kg, while higher Qm were observed in the ditch sediments from the paddy fields. The Qm was significantly and positively correlated with oxalate-extractable Fe and Al oxides (r=0.97 and 0.98, p < 0.01), clay fraction (r = 0.78, p < 0.05) and organic matter (r = 0.95, p < 0.01). Sediment pH, clay and organic matter influenced the P sorption through amorphous Fe and Al oxides. CaCO3 content was negatively correlated with the Qm (r = -0.83, p < 0.05), implying that saturated CaCO3 (> 50 g/kg) would not increase P sorption capacity in the ditch sediments. The ditch sediments featured a linear desorption curve, suggesting that P release risk would be enhanced with the increase of the P adsorption. The P desorption rate was positively correlated with Olsen P (r = 0.94, p < 0.01), but negatively related to the fine particle-size fractions (r = -0.92, p < 0.01), the sum of the amorphous Fe and Al oxides (r = -0.67, p < 0.05) and the P sorption capacity (r = -0.59, p < 0.05). The ditch sediments from residential area had a higher P release risk than that from the other ditches of forestland, sloping cropland and paddy field. The P sorption index (PSI) derived from single-point measurement was significantly correlated with the P sorption capacity (r = 0.99, p < 0.01), and could be used for estimating Qm as 1.64 times PSI plus 24.0 (Qm = 1.64 PSI + 24.0) for similar sediments with highly calcareous soils and sediments. Ditch cleaning and sediment removal for the ditch in residential area were recommended in this area to reduce the P release risk.
基金Project 2006A021 supported by the Science Foundation of China University of Mining & Technology
文摘Graphite antimony composites were prepared using a mechanical pressure infiltration method to force molten antimony into graphite preforms having a percolation micro-structure and a hop-pocket power filler. The micro-structural and macroscopic properties of the graphite antimony composites were analysed. Observations included metallographic analysis, physical properties and friction and wear behaviour. The results show that the wear loss is decreased by 12.24% and that the friction coefficient is re-duced by 32.61% after hop-pocket power was used. The research indicates that the hop-pocket power method gives a useful way to reduce friction coefficients and wear loss, and to increase service life and self-lubrication properties, of the graphite antimony seal-ing material as compared to carbon black.
文摘在全面推广高速公路差异化收费背景下,针对如何选取差异化收费路段的问题,建立一种基于多源数据的差异化收费路段识别方法.首先,基于高速公路门架数据、收费站出入口流量、普通国省道交通流量自动观测站数据等多源数据,从路段沿线社会经济发展水平、网络化水平、交通运行特征、交通可转移性、交通负荷均衡性5个维度,构建高速公路差异化收费路段识别指标体系.然后,基于k-means聚类和分类回归树算法(Classification and Regression Trees,CART)建立高速公路差异化收费路段识别模型.最后,以云南省130条高速公路路段为例,提取高速公路差异化收费路段细分规则及关键特征指标.研究结果表明:影响高速公路差异化收费路段细分的关键特征指标分别为路段成网率、收费站节点度、出行成本偏差率、路段全天小时拥挤度、可替代路径数量;根据决策树细分规则可将差异化收费路段划分为差异化上浮型、不适合差异化、差异化下浮型3种,符合高速公路实际收费运营情况.
