The preferred orientation of clay minerals dominates the intrinsic anisotropy of shale. We introduce the clay lamination （CL） parameter to the Backus averaging method to describe the intrinsic shale anisotropy induc...The preferred orientation of clay minerals dominates the intrinsic anisotropy of shale. We introduce the clay lamination （CL） parameter to the Backus averaging method to describe the intrinsic shale anisotropy induced by the alignment of clay minerals. Then, we perform the inversion of CL and the Thomsen anisotropy parameters. The direct measurement of anisotropy is difficult because of the inability to measure the acoustic velocity in the vertical direction in boreholes and instrument limitations. By introducing the parameter CL, the inversion method provides reasonable estimates of the elastic anisotropy in the Longmaxi shale. The clay content is weakly correlated with the CL parameter. Moreover, the parameter CL is abnormally high at the bottom of the Longmaxi and Wufeng Formations, which are the target reservoirs. Finally, we construct rock physics templates to interpret well logging and reservoir properties.展开更多
不透水层是指能够隔离地表水渗透到土壤的覆盖表面,以不透水层分布变化来研究铜川城市化进程。利用决策树分类结合生物物理成分指数(BCI)和裸土指数(MBSI)的方法对1986,1991,1996,2002,2007,2012和2017年的遥感影像数进行不透水层提取,...不透水层是指能够隔离地表水渗透到土壤的覆盖表面,以不透水层分布变化来研究铜川城市化进程。利用决策树分类结合生物物理成分指数(BCI)和裸土指数(MBSI)的方法对1986,1991,1996,2002,2007,2012和2017年的遥感影像数进行不透水层提取,采用指标分析、重心轨迹偏移等方法探究不透水层空间扩展特征,并结合统计年鉴、DEM数据研究铜川市不透水层扩展驱动机制。结果表明:文中提出的基于决策树分类模型结合BCI和MBSI的方法对不透水层提取与验证数据的拟合优度达到0.88.铜川市的不透水层面积持续增加,面积从1986年的5.7 km 2增加到2017年的61.5 km 2,年均增长速度高达1.8%,特别是2007—2017年是快速城市化时期,增长面积占31 a变化总面积的69.3%.不透水层的重心呈先北后南的阶段性变化,1986—2002年向北移动,2002—2007年向南移动,2007—2017年继续向西南方向移动。通过对驱动力指标分析表明,经济及人口增长对不透水层扩展有着直接推动作用,矿产资源分布、地理环境限制和规划政策引导为影响研究区不透水层变化的主要因素。展开更多
[Objective] The aim was to carry out study on characteristics of phytoplankton and its correlation with water environment in SFTWs. [Method] Based on the pilot-scale SFTWs in Hongqiao transportation hub of Shanghai,ph...[Objective] The aim was to carry out study on characteristics of phytoplankton and its correlation with water environment in SFTWs. [Method] Based on the pilot-scale SFTWs in Hongqiao transportation hub of Shanghai,phytoplankton＇s community structure,diversity index and their correlation with water purification performance were investigated. [Result] 57 species of seven phylum of phytoplankton were detected in this tested river,including 12 species of Cyanophyta,2 of Cryptophyta,10 of Bacillariophyta,1 of Xanthophyta,7 of Euglenophyta,1 of Pyrrophyta and 24 of Chlorophyta,respectively. Additionally,it was found that Cyanophyta was the dominant phytoplankton,followed by Bacillariophyta and Cyanophyta. Biological density was far more than 10×105 ind./L,thus it could be considered that the river was eutrophic. The range of Shannon-Wiener index was 0.6-2.2,Pielou index was 0.5-2.5 and Margalef index＇s range was 0.35-0.85,which could further prove that the water was eutrophic. The biological density and species were significantly positively correlated with temperature and N content,indicating that the absorption of N by phytoplankton was the main N-removal pathway in SFTWs. [Conclusion] This study had provided basis for the river regulation and ecological restoration.展开更多
In this paper, we consider the secure data transmission over α-η-κ-μ fading channels, which are recently proposed to encompass nearly all the well-known statistical models adopted in the literature. In particular,...In this paper, we consider the secure data transmission over α-η-κ-μ fading channels, which are recently proposed to encompass nearly all the well-known statistical models adopted in the literature. In particular, we address the secrecy performance in terms of the average secrecy capacity(ASC) and the secrecy outage probability(SOP), for which novel analytical expressions are derived. Simulation results verify the analysis and demonstrate the impact of the physical parameters on the secrecy performance of this new channel fading model.展开更多
Various kinds of human disturbances on cropland are the main reasons for soil erosion and land degradation.Farming practices in mountainous areas vary greatly among cropland plots because of the heterogeneity of bioph...Various kinds of human disturbances on cropland are the main reasons for soil erosion and land degradation.Farming practices in mountainous areas vary greatly among cropland plots because of the heterogeneity of biophysical conditions and differences in farmers'management behavior.The main purpose of this paper is to develop a composite index of cropland physical disturbance intensity(CLDI)to reflect the plot-scale discrepancy of potential soil erosion in mountainous areas.The study was based on both plot survey and household interview data,collected from six typical catchments in mountainous areas of southwestern China.Four kinds of physical disturbance practices and two kinds of conservation practices during one crop rotation period were synthesized to develop the CLDI index.The rough set theory was referenced to avoid subjectivity during weight allocation.The results show that conventional tillage,deep fertilization,and manual weeding are the main causes of cropland soil erosion,whereas manure application in combination with seasonal fallow reduces soil erosion.Different crop types as well as cropland location factors determine the spatial pattern of CLDI.Crop rotation modes with major crops of tobacco and maize resulted in a maximal CLDI,and cropland plots with a distance radius of 150 meters away from households received the most intensive physical disturbance.These results are critical to help better protect rural environments in mountainous areas.Based on the results,methods to reduce cropland soil erosion are suggested.展开更多
基金supported by the Foundation of State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development(No.G5800-16-ZS-KFZY002)the NSFC and Sino PEC Joint Key Project(No.U1663207)the National Natural Science Foundation of China(No.41404090)
文摘The preferred orientation of clay minerals dominates the intrinsic anisotropy of shale. We introduce the clay lamination （CL） parameter to the Backus averaging method to describe the intrinsic shale anisotropy induced by the alignment of clay minerals. Then, we perform the inversion of CL and the Thomsen anisotropy parameters. The direct measurement of anisotropy is difficult because of the inability to measure the acoustic velocity in the vertical direction in boreholes and instrument limitations. By introducing the parameter CL, the inversion method provides reasonable estimates of the elastic anisotropy in the Longmaxi shale. The clay content is weakly correlated with the CL parameter. Moreover, the parameter CL is abnormally high at the bottom of the Longmaxi and Wufeng Formations, which are the target reservoirs. Finally, we construct rock physics templates to interpret well logging and reservoir properties.
文摘不透水层是指能够隔离地表水渗透到土壤的覆盖表面,以不透水层分布变化来研究铜川城市化进程。利用决策树分类结合生物物理成分指数(BCI)和裸土指数(MBSI)的方法对1986,1991,1996,2002,2007,2012和2017年的遥感影像数进行不透水层提取,采用指标分析、重心轨迹偏移等方法探究不透水层空间扩展特征,并结合统计年鉴、DEM数据研究铜川市不透水层扩展驱动机制。结果表明:文中提出的基于决策树分类模型结合BCI和MBSI的方法对不透水层提取与验证数据的拟合优度达到0.88.铜川市的不透水层面积持续增加,面积从1986年的5.7 km 2增加到2017年的61.5 km 2,年均增长速度高达1.8%,特别是2007—2017年是快速城市化时期,增长面积占31 a变化总面积的69.3%.不透水层的重心呈先北后南的阶段性变化,1986—2002年向北移动,2002—2007年向南移动,2007—2017年继续向西南方向移动。通过对驱动力指标分析表明,经济及人口增长对不透水层扩展有着直接推动作用,矿产资源分布、地理环境限制和规划政策引导为影响研究区不透水层变化的主要因素。
基金Supported by Major Subject of National Science and Technology(2009ZX07317-006 )Shanghai Key Scientific and Technological Issues (062312019)~~
文摘[Objective] The aim was to carry out study on characteristics of phytoplankton and its correlation with water environment in SFTWs. [Method] Based on the pilot-scale SFTWs in Hongqiao transportation hub of Shanghai,phytoplankton＇s community structure,diversity index and their correlation with water purification performance were investigated. [Result] 57 species of seven phylum of phytoplankton were detected in this tested river,including 12 species of Cyanophyta,2 of Cryptophyta,10 of Bacillariophyta,1 of Xanthophyta,7 of Euglenophyta,1 of Pyrrophyta and 24 of Chlorophyta,respectively. Additionally,it was found that Cyanophyta was the dominant phytoplankton,followed by Bacillariophyta and Cyanophyta. Biological density was far more than 10×105 ind./L,thus it could be considered that the river was eutrophic. The range of Shannon-Wiener index was 0.6-2.2,Pielou index was 0.5-2.5 and Margalef index＇s range was 0.35-0.85,which could further prove that the water was eutrophic. The biological density and species were significantly positively correlated with temperature and N content,indicating that the absorption of N by phytoplankton was the main N-removal pathway in SFTWs. [Conclusion] This study had provided basis for the river regulation and ecological restoration.
基金supported by the Fundamental Research Funds for the Center University of China under Grant HIT. MKSTISP. 2016 13
文摘In this paper, we consider the secure data transmission over α-η-κ-μ fading channels, which are recently proposed to encompass nearly all the well-known statistical models adopted in the literature. In particular, we address the secrecy performance in terms of the average secrecy capacity(ASC) and the secrecy outage probability(SOP), for which novel analytical expressions are derived. Simulation results verify the analysis and demonstrate the impact of the physical parameters on the secrecy performance of this new channel fading model.
基金jointly funded by the National Key Basic Research Program of China (973 program) (Grant NO.2015CB452702)the National Natural Science Foundation of China (Grant NO.41371539)partially supported by the CDM Fund Grant Project in China (Grant NO. 2013030)
文摘Various kinds of human disturbances on cropland are the main reasons for soil erosion and land degradation.Farming practices in mountainous areas vary greatly among cropland plots because of the heterogeneity of biophysical conditions and differences in farmers'management behavior.The main purpose of this paper is to develop a composite index of cropland physical disturbance intensity(CLDI)to reflect the plot-scale discrepancy of potential soil erosion in mountainous areas.The study was based on both plot survey and household interview data,collected from six typical catchments in mountainous areas of southwestern China.Four kinds of physical disturbance practices and two kinds of conservation practices during one crop rotation period were synthesized to develop the CLDI index.The rough set theory was referenced to avoid subjectivity during weight allocation.The results show that conventional tillage,deep fertilization,and manual weeding are the main causes of cropland soil erosion,whereas manure application in combination with seasonal fallow reduces soil erosion.Different crop types as well as cropland location factors determine the spatial pattern of CLDI.Crop rotation modes with major crops of tobacco and maize resulted in a maximal CLDI,and cropland plots with a distance radius of 150 meters away from households received the most intensive physical disturbance.These results are critical to help better protect rural environments in mountainous areas.Based on the results,methods to reduce cropland soil erosion are suggested.
