With the discovery of ultra-deepwater and ultra-shallow large natural gas reservoirs in the South China Sea,unconsolidated sandstone reservoirs have once again become a focal point of research.In response to the uncle...With the discovery of ultra-deepwater and ultra-shallow large natural gas reservoirs in the South China Sea,unconsolidated sandstone reservoirs have once again become a focal point of research.In response to the unclear controlling factors and the need for connectivity evaluation of unconsolidated sandstone reservoirs in the Ledong formation of the Lingshui A area in the Qiongdongnan Basin,this study employs a range of experimental techniques,namely,cast thin sections,scanning electron microscopy,Xray diffraction mineral analysis,laser granulometry,and nuclear magnetic resonance(NMR),to investigate the microstructural characteristics of these reservoirs.The primary objective is to elucidate the controlling mechanisms behind pore-throat variability and to identify how sedimentary factors,mineral composition,and gas hydrate occurrence modes collectively influence pore-throat structural characteristics.Guided by fractal theory,a multidimensional analysis of pore-throat modal characteristics is conducted using a combination of image analysis,mercury intrusion capillary pressure,and NMR techniques.Furthermore,connectivity evaluation factors(CEFs)are constructed based on reservoir parameters to quantitatively assess reservoir connectivity and to establish connectivity evaluation standards.Results indicate that sedimentary factors are the principal determinants of pore-throat differences in the study area.Coarse grains,low clay content,and enhanced reservoir porosity contribute to improved permeability.At the microscopic level,variations in mineral composition also play a critical role.Higher quartz content and reduced clay mineral content,particularly illite and chlorite,are associated with excellent reservoir properties.By contrast,diagenesis exhibits a limited effect on reservoir quality.The gas hydrate occurrence state is characterized as a pore suspension type,exhibiting a relatively uniform pore-throat distribution.This load-bearing hydrate type may enhance pore-throat heterogeneity.Pore-throat modes are classified into three types:bimodal,multimodalⅠ,and multimodalⅡ.The bimodal hydrate occurrence state is dominated by the pore suspension type and characterized by low sorting coefficients,reduced fractal dimensions,increased uniform pore-throat structures,and improved reservoir connectivity.Five key reservoir parameters are selected,forming the basis of the CEFs,which comprehensively characterize reservoir connectivity.Ultimately,a connectivity evaluation standard and a microscopic connectivity model for typical unconsolidated sandstones in the South China Sea are established,providing critical guidance for future reservoir development strategies.展开更多
Bacillus amyloliquefaciens YP6,a plant growth promoting rhizobacteria,is capable of efficiently degrading a wide range of organophosphorus pesticides(OPs).Here,we report the complete genome sequence of this bacterium ...Bacillus amyloliquefaciens YP6,a plant growth promoting rhizobacteria,is capable of efficiently degrading a wide range of organophosphorus pesticides(OPs).Here,we report the complete genome sequence of this bacterium with a genome size of 4009619 bp,4210 protein-coding genes and an average GC content of 45.9%.Based on the genome sequence,several genes previously described as being involved in solubilizing-phosphorus,OPs-degradation,indole-3-acetic acid(IAA)and siderophores synthesis.Interestingly,compared with the genomes of B.amyloliquefaciens species,strain YP6 had larger genome size and the most protein-coding genes.Moreover,the four categories of“cell envelope biogenesis,outer membrane(M),”“translation,ribosomal structure and biogenesis(J),”“transcription(K),”and“signal transduction mechanisms(T)”were fewer.These differences may be related to extensive environmental adaptability of the genus B.amyloliquefaciens.These results expand the application potential of strain YP6 for environmental bioremediation,provide gene resources involved in OPs degradation for biotechnology and gene engineering,and contribute to provide insights into the relationship between microorganism and living environment.展开更多
Soil strain is the key parameter to control the elasto-plastic deformation and even the failure processes.To overcome the defect that the strain of the model soil is always smaller than that of the prototype in Iai′s...Soil strain is the key parameter to control the elasto-plastic deformation and even the failure processes.To overcome the defect that the strain of the model soil is always smaller than that of the prototype in Iai′s generalized scaling law(GSL),a modified scaling law was proposed based on Iai′s GSL to secure the same dynamic shear strain between the centrifuge model and the prototype by modulating the amplitude and frequency of the input motion at the base.A suite of dynamic centrifuge model tests of dry sand level ground was conducted with the same overall scaling factor(λ=200)under different centrifugal accelerations by using the technique of“modeling of models”to validate the modified GSL.The test results show that the modified GSL could achieve the same dynamic strain in model as that of the prototype,leading to better modeling for geotechnical problems where dynamic strain dominates the response or failure of soils.Finally,the applicability of the proposed scaling law and possible constraints on geometry scaling due to the capability limits of existing centrifuge shaking tables are discussed.展开更多
Direct oxidation of composite Al/Ti metal films as gate insulators for AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistors(MOSHEMTs/HEMTs)is successfully realized.The devices fabricated with this no...Direct oxidation of composite Al/Ti metal films as gate insulators for AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistors(MOSHEMTs/HEMTs)is successfully realized.The devices fabricated with this novel process exhibit four orders of magnitude reduction in gate leakage current and remarkable breakdown voltage(V br=490 V vs 88 V for normal HEMT)improvement,compared with conventional Schottky-gate HEMTs.Furthermore,the transconductance of the MOSHEMT is only slightly lower(2.6%)than that of Schottky-gate HEMTs and have a wider full width of half maximum.The notable enhancement in device performance renders this new process highly promising for GaN-based microwave power amplifier applications in communication and radar systems.展开更多
探究资源型城市在煤炭资源开采和城市化推进等人类活动驱动下,土地利用类型变化对区域生态服务和功能的影响,对区域土地利用规划调整和生态系统保护的重要意义.基于1990-2021年期间淮北市土地利用数据,采用当量因子法及RS、GIS技术分别...探究资源型城市在煤炭资源开采和城市化推进等人类活动驱动下,土地利用类型变化对区域生态服务和功能的影响,对区域土地利用规划调整和生态系统保护的重要意义.基于1990-2021年期间淮北市土地利用数据,采用当量因子法及RS、GIS技术分别对淮北市土地利用和生态服务价值(Ecosystem Service Values, ESV)的结构、变化进行全面分析,探讨土地利用对ESV的损益效应.结果表明:1990-2021年淮北市土地利用变化显著,林地、草地和建设用地增加,耕地面积减少.其中耕地面积减幅最大,共计607.956 km^(2).1990年淮北市ESV为3.524×10^(5)万元,2021年为0.3019×10^(5)万元,30年间共损失0.505×10^(5)万元.1990-2021年,不同土地利用类型中,林地和草地的ESV显著增加,增量分别为1.27×10^(4)万元和0.51×10^(4)万元,变化率分别为207.93%和33.31%.耕地和水域ESV之和超过总值的87%.服务功能中除水文调节和提供美学景观价值有小幅增加之外,其他各项均有降低.1990-2021年,淮北市社会经济的快速发展对土地利用结构和ESV产生重要影响,耕地面积和ESV总量减少,多数生态服务功能价值有下降趋势.今后土地利用规划调整中需加大关注水域和林地的保护和开发力度.展开更多
基金Program‘Geological Reservoir Digital Analogy Study Based on Exploration and Development Data Lake’(No.KJZH2024-2903)。
文摘With the discovery of ultra-deepwater and ultra-shallow large natural gas reservoirs in the South China Sea,unconsolidated sandstone reservoirs have once again become a focal point of research.In response to the unclear controlling factors and the need for connectivity evaluation of unconsolidated sandstone reservoirs in the Ledong formation of the Lingshui A area in the Qiongdongnan Basin,this study employs a range of experimental techniques,namely,cast thin sections,scanning electron microscopy,Xray diffraction mineral analysis,laser granulometry,and nuclear magnetic resonance(NMR),to investigate the microstructural characteristics of these reservoirs.The primary objective is to elucidate the controlling mechanisms behind pore-throat variability and to identify how sedimentary factors,mineral composition,and gas hydrate occurrence modes collectively influence pore-throat structural characteristics.Guided by fractal theory,a multidimensional analysis of pore-throat modal characteristics is conducted using a combination of image analysis,mercury intrusion capillary pressure,and NMR techniques.Furthermore,connectivity evaluation factors(CEFs)are constructed based on reservoir parameters to quantitatively assess reservoir connectivity and to establish connectivity evaluation standards.Results indicate that sedimentary factors are the principal determinants of pore-throat differences in the study area.Coarse grains,low clay content,and enhanced reservoir porosity contribute to improved permeability.At the microscopic level,variations in mineral composition also play a critical role.Higher quartz content and reduced clay mineral content,particularly illite and chlorite,are associated with excellent reservoir properties.By contrast,diagenesis exhibits a limited effect on reservoir quality.The gas hydrate occurrence state is characterized as a pore suspension type,exhibiting a relatively uniform pore-throat distribution.This load-bearing hydrate type may enhance pore-throat heterogeneity.Pore-throat modes are classified into three types:bimodal,multimodalⅠ,and multimodalⅡ.The bimodal hydrate occurrence state is dominated by the pore suspension type and characterized by low sorting coefficients,reduced fractal dimensions,increased uniform pore-throat structures,and improved reservoir connectivity.Five key reservoir parameters are selected,forming the basis of the CEFs,which comprehensively characterize reservoir connectivity.Ultimately,a connectivity evaluation standard and a microscopic connectivity model for typical unconsolidated sandstones in the South China Sea are established,providing critical guidance for future reservoir development strategies.
基金financially supported by the Collaborative Innovation Involving Production, Teaching & Research Funds of Jiangsu Province, China (BY2014023-28)
文摘Bacillus amyloliquefaciens YP6,a plant growth promoting rhizobacteria,is capable of efficiently degrading a wide range of organophosphorus pesticides(OPs).Here,we report the complete genome sequence of this bacterium with a genome size of 4009619 bp,4210 protein-coding genes and an average GC content of 45.9%.Based on the genome sequence,several genes previously described as being involved in solubilizing-phosphorus,OPs-degradation,indole-3-acetic acid(IAA)and siderophores synthesis.Interestingly,compared with the genomes of B.amyloliquefaciens species,strain YP6 had larger genome size and the most protein-coding genes.Moreover,the four categories of“cell envelope biogenesis,outer membrane(M),”“translation,ribosomal structure and biogenesis(J),”“transcription(K),”and“signal transduction mechanisms(T)”were fewer.These differences may be related to extensive environmental adaptability of the genus B.amyloliquefaciens.These results expand the application potential of strain YP6 for environmental bioremediation,provide gene resources involved in OPs degradation for biotechnology and gene engineering,and contribute to provide insights into the relationship between microorganism and living environment.
基金National Natural Science Foundation of China under Grant Nos.51988101,51978613 and 52278374the Chinese Program of Introducing Talents of Discipline to University(the 111 Project,B18047)。
文摘Soil strain is the key parameter to control the elasto-plastic deformation and even the failure processes.To overcome the defect that the strain of the model soil is always smaller than that of the prototype in Iai′s generalized scaling law(GSL),a modified scaling law was proposed based on Iai′s GSL to secure the same dynamic shear strain between the centrifuge model and the prototype by modulating the amplitude and frequency of the input motion at the base.A suite of dynamic centrifuge model tests of dry sand level ground was conducted with the same overall scaling factor(λ=200)under different centrifugal accelerations by using the technique of“modeling of models”to validate the modified GSL.The test results show that the modified GSL could achieve the same dynamic strain in model as that of the prototype,leading to better modeling for geotechnical problems where dynamic strain dominates the response or failure of soils.Finally,the applicability of the proposed scaling law and possible constraints on geometry scaling due to the capability limits of existing centrifuge shaking tables are discussed.
基金Supported by the National Natural Science Foundation of China under Grant Nos.60406004 and 60736033Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices of the Ministry of Education,Microelectronics Institute,Xidian University.
文摘Direct oxidation of composite Al/Ti metal films as gate insulators for AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistors(MOSHEMTs/HEMTs)is successfully realized.The devices fabricated with this novel process exhibit four orders of magnitude reduction in gate leakage current and remarkable breakdown voltage(V br=490 V vs 88 V for normal HEMT)improvement,compared with conventional Schottky-gate HEMTs.Furthermore,the transconductance of the MOSHEMT is only slightly lower(2.6%)than that of Schottky-gate HEMTs and have a wider full width of half maximum.The notable enhancement in device performance renders this new process highly promising for GaN-based microwave power amplifier applications in communication and radar systems.
文摘探究资源型城市在煤炭资源开采和城市化推进等人类活动驱动下,土地利用类型变化对区域生态服务和功能的影响,对区域土地利用规划调整和生态系统保护的重要意义.基于1990-2021年期间淮北市土地利用数据,采用当量因子法及RS、GIS技术分别对淮北市土地利用和生态服务价值(Ecosystem Service Values, ESV)的结构、变化进行全面分析,探讨土地利用对ESV的损益效应.结果表明:1990-2021年淮北市土地利用变化显著,林地、草地和建设用地增加,耕地面积减少.其中耕地面积减幅最大,共计607.956 km^(2).1990年淮北市ESV为3.524×10^(5)万元,2021年为0.3019×10^(5)万元,30年间共损失0.505×10^(5)万元.1990-2021年,不同土地利用类型中,林地和草地的ESV显著增加,增量分别为1.27×10^(4)万元和0.51×10^(4)万元,变化率分别为207.93%和33.31%.耕地和水域ESV之和超过总值的87%.服务功能中除水文调节和提供美学景观价值有小幅增加之外,其他各项均有降低.1990-2021年,淮北市社会经济的快速发展对土地利用结构和ESV产生重要影响,耕地面积和ESV总量减少,多数生态服务功能价值有下降趋势.今后土地利用规划调整中需加大关注水域和林地的保护和开发力度.
