检索结果-南通市图书馆

基于GIS格网模型的广州市土地生态安全格局演化

在线全文

学校读者我要写书评

暂无评论

科技和产业 2024年第3期24卷 216-222页

作者：聂嘉琦刘光盛池杰华南农业大学公共管理学院广州510640 自然资源部华南热带亚热带自然资源监测重点实验室广州510700 广东省粤港澳大湾区地理科学数据中心广州510700 山东建筑大学设计集团有限公司济南250000

以公里格网为评价单元,构建基于PSR-NES(压力-状态-响应和经济-环境-社会)模型的土地生态安全测度指标体系,运用突变级数法动态识别2010—2020年广州市土地生态安全格局。结果表明:广州土地生态安全水平空间异质性较为明显,整体呈现“... 详细信息

以公里格网为评价单元,构建基于PSR-NES(压力-状态-响应和经济-环境-社会)模型的土地生态安全测度指标体系,运用突变级数法动态识别2010—2020年广州市土地生态安全格局。结果表明:广州土地生态安全水平空间异质性较为明显,整体呈现“中间低,四周高”的分布格局;2010—2020年,广州市土地生态安全水平先下降后提高,其中,北部生态涵养区土地生态安全水平呈下降趋势,南部生态调节区土地生态安全状况逐渐好转,中部建成区土地生态安全状况不容乐观。未来城镇扩张应尽量避免侵占土地生态安全水平较高的区域,可通过分区治理,科学布局生产、生活、生态空间,优化产业结构,加强生态用地保护力度等措施持续改善土地生态安全状况。

关键词：土地生态安全 GIS(地理信息系统)格网突变级数法空间分异广州市

A New Method of Identifying 3D Null Points in Solar Vector Magnetic Fields

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Astronomy and Astrophysics 2005年第5期5卷 443-447页

作者： Hui Zhao Jing-Xiu Wang Jun Zhang chi-jie Xiao National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

Employing the Poincar6 index of isolated null-points in a vector field, we worked out a mathematical method of searching for 3D null-points in coronal magnetic fields. After introducing the relevant differential topology, we test the method by using the analytical model of Brown ＆ Priest. The location of nullpoint identified by our method coincides precisely with the analytical solution. Finally we apply the method to the 3D coronal magnetic fields reconstructed from an observed MDI magnetogram of a super-active region （NOAA 10488）. We find that the 3D null-point seems to be a key element in the magnetic topology associated with flare occurrence.

关键词： Sun: flares - Sun: corona- Sun: magnetic fields

A modern survey method for determining live loads based on multi-source and open-access data on the Internet

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2024年第8期18卷 1135-1147页

作者： chi XU Jun CHEN jie LI School of Civil Engineering Tongji UniversityShanghai 200092China The State Key Laboratory on Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China

Sufficient survey data are required to describe the stochastic behaviors of live ***,due to manual and on-site operation required by traditional survey methods,traditional surveys face challenges like occupant resistance,high costs,and long implementation *** study proposes a new survey method to access live load data online and *** samples are acquired from multi-source,open-access and dynamically updated data on the *** change intervals,geometrical dimensions and object quantities are obtained from transaction information,building attributes and virtual reality models on real estate websites,*** object weights are collected from commodity information on e-commerce *** integration of the aforementioned data allows for the extraction of necessary statistics to describe a live load *** proposed method is applied to a live load survey in china,covering 20040 m^(2),with around 90000 samples acquired for object weights and load *** survey results reveal that about 70%−80%of the amplitude statistics are attributable to 1/6 of the total object types.

关键词： live load online survey method data acquisition data integration

A novel numerical simulation of CO_(2) immiscible flooding coupled with viscosity and starting pressure gradient modeling in ultra-low permeability reservoir

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Earth Science 2023年第3期17卷 884-898页

作者： jie chi Binshan JU Jiabei WANG Xing ZHANG Wenbin CHEN Mengfei ZHANG School of Big Data and Fundamental Sciences Shandong Institute of Petroleum and Chemical TechnologyDongying 257061China School of Energy Resources China University of Geosciences(Beijing)Beijing 100083China Key Laboratory of Geological Evaluation and Development Engineering of Unconventional Natural Gas Energy Beijing 100083China School of Petroleum Engineering Chongqing University of Science&TechnologyChongqing 401331China Research Institute of Petroleum Engineering Technology Shengli Oilfield CompanySINOPECDongying 257000China

CO_(2) immiscible flooding is an environmentally-friendly and effective method to enhance oil recovery in ultra-low permeability reservoirs.A mathematical model of CO_(2) immiscible flooding was developed,considering the variation in crude oil viscosity and starting pressure gradient in ultra-low permeability reservoirs based on the non-Darcy percolation *** mathematical model and numerical simulator were developed in the C++language to simulate the effects of fluid viscosity,starting pressure gradient,and other physical parameters on the distribution of the oil pressure field,oil saturation field,gas saturation field,oil viscosity field,and oil *** results showed that the formation pressure and pressure propagation velocity in CO_(2) immiscible flooding were lower than the findings without considering the starting pressure *** formation oil content saturation and the crude oil formation viscosity were higher after the consideration of the starting pressure *** viscosity of crude oil considering the initiation pressure gradient during the formation was higher than that without this gradient,but the yield was lower than that *** novel mathematical models helped the characterization of seepage resistance,revealed the influence of fluid property changes on seepage,improved the mathematical model of oil seepage in immiscible flooding processes,and guided the improvement of crude oil recovery in immiscible flooding processes.

关键词： viscosity starting pressure gradient flow simulation CO_(2)immiscible flooding ultra-low permeability reservoir

Determination of the Topology Skeleton of Magnetic Fields in a Solar Active Region

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Astronomy and Astrophysics 2008年第2期8卷 133-145页

作者： Hui Zhao Jing-Xiu Wang Jun Zhang chi-jie Xiao Hai-Min Wang National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 Big Bear Solar Observatory 40386 North Shore Lane Big Bear City CA 92314 USA

Magnetic topology has been a key to the understanding of magnetic energy release mechanism. Based on observed vector magnetograms, we have determined the threedimensional （3D） topology skeleton of the magnetic fields in the active region NOAA 10720. The skeleton consists of six 3D magnetic nulls and a network of corresponding spines, fans, and null-null lines. For the first time, we have identified a spiral magnetic null in Sun＇s corona. The magnetic lines of force twisted around the spine of the null, forming a ＇magnetic wreath＇ with excess of free magnetic energy and resembling observed brightening structures at extraultraviolet （EUV） wavebands. We found clear evidence of topology eruptions which are referred to as catastrophic changes of topology skeleton associated with a coronal mass ejection （CME） and an explosive X-ray flare. These results shed new lights on the structural complexity and its role in explosive magnetic activity. The concept of flux rope has been widely used in modelling explosive magnetic activity, although their observational identity is rather obscure or, at least, lacking of necessary details up to date. We suggest that the magnetic wreath associated with the 3D spiral null is likely an important class of the physical entity of flux ropes.

关键词： Sun: magnetic fields -- Sun: solar corona -- Sun: activity

Influence of bifurcation position and length of side chains on the structure of isoindigo-based conjugated polymer thin films

在线全文

学校读者我要写书评

暂无评论

chinese Chemical Letters 2017年第2期28卷 333-337页

作者： Shuai-jie chi Liang Chen Jian-Gang Liu Xin-Hong Yu Yan-Chun Han State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 China University of the chinese Academy of Sciences Beijing 100049 China

We chose a series of isoindigo-based conjugated polymer（ⅡDDT,ⅡDDT-C3 and ⅡDDT-C4） with different length of side chains and bifurcation positions to investigate the relationship between the degree of alignment and the length of side chains and bifurcation *** found that the dichroic ratio was increased from 2.37 to 5.23 when the side chain was longer and the bifurcation position was away from the *** π-π stacking distance was decreased from 3.67 A to 3.61 A when the bifurcation position was away from the backbone because of its smaller hindrance and the d-spacing of the（100）was increased from 20.06 A to 25.21 A when the side chain was *** the polymers were adopted an edge-on orientation with the backbone paralleled with the long axis of *** weak interaction of side-chain in ⅡDDT-C4 was beneficial for the molecules being rearranged in parallel during the contact line receding and the strong n-n interaction could accelerate the interchain assembly of the parallel molecules through π-π interaction to form aligned fibers.

关键词： Isoindigo-based conjugated polymers Alignment The length of side chains Bifurcation positions π-π interaction

Laboratory simulation of CO_(2) immiscible gas flooding and characterization of seepage resistance

在线全文

学校读者我要写书评

暂无评论

Frontiers of Earth Science 2023年第3期17卷 797-817页

作者： jie chi Binshan JU Wenbin CHEN Mengfei ZHANG Rui ZHANG Anqi MIAO Dayan WANG Fengyun CUI School of Big Data and Fundamental Sciences Shandong Institute of Petroleum and Chemical TechnologyDongying 257061China School of Energy Resources China University of Geosciences(Beijing)Beijing 100083China Key Laboratory of Geological Evaluation and Development Engineering of Unconventional Natural Gas Energy Beijing 100083China School of Chemical Engineering Shandong Institute of Petroleum and Chemical TechnologyDongying 257061China

CO_(2) flooding can significantly improve the recovery rate, effectively recover crude oil, and has the advantages of energy saving and emission reduction. At present, most domestic researches on CO_(2) flooding seepage experiments are field tests in actual reservoirs or simulations with reservoir numerical simulators. Although targeted, the promotion is poor. For the characterization of seepage resistance, there are few studies on the variation law of seepage resistance caused by the combined action in the reservoir. To solve this problem, based on the mechanism of CO_(2), a physical simulation experiment device for CO_(2) non-miscible flooding production manner is designed. The device adopts two displacement schemes, gas-displacing water and gas-displacing oil, it mainly studies the immiscible gas flooding mechanism and oil displacement characteristics based on factors such as formation dip angle, gas injection position, and gas injection rate. It can provide a more accurate development simulation for the actual field application. By studying the variation law of crude oil viscosity and start-up pressure gradient, the characterization method of seepage resistance gradient affected by these two factors in the seepage process is proposed. The field test is carried out for the natural core of the S oilfield, and the seepage resistance is described more accurately. The results show that the advancing front of the gas drive is an arc, and the advancing speed of the gas drive oil front is slower than that of gas drive water;the greater the dip angle, the higher the displacement efficiency;the higher the gas injection rate is, the higher the early recovery rate is, and the lower the later recovery rate is;oil displacement efficiency is lower than water displacement efficiency;taking the actual core of S oilfield as an example, the mathematical representation method of core start-up pressure gradient in low permeability reservoir is established.

关键词： laboratory_simulation viscosity starting pressure gradient CO immiscible flooding characterization of seepage resistance

新课标理念下高中化学探究式实验教学研究——以“原电池的工作原理”为例

在线全文

学校读者我要写书评

暂无评论

云南化工 2024年第4期51卷 183-185页

作者：段超迟捷付甜尚永辉王宏社宝鸡文理学院化学化工学院陕西宝鸡721013 咸阳师范学院化学与化工学院陕西咸阳712000

探究式实验教学是高中化学实验的一种重要教学方式,研究新课标理念下实验探究活动对中学化学实验教学具有重要的意义。在新课标要求的大背景下,基于建构主义学习理论、布鲁纳认知-发现理论的指导作用,对人教版(2019版)“原电池的工作原... 详细信息

探究式实验教学是高中化学实验的一种重要教学方式,研究新课标理念下实验探究活动对中学化学实验教学具有重要的意义。在新课标要求的大背景下,基于建构主义学习理论、布鲁纳认知-发现理论的指导作用,对人教版(2019版)“原电池的工作原理”进行了探究式实验教学研究,以期对中学化学实验教学提供一些建议。

关键词：新课标高中化学探究式实验教学

“宏-微-符”三重表征法在中学化学实验教学中的应用--以“Fe^(2+)与Fe^(3+)的检验”为例

在线全文

学校读者我要写书评

暂无评论

云南化工 2024年第2期51卷 182-184页

作者：迟捷段超付甜尚永辉王宏社宝鸡文理学院化学化工学院陕西宝鸡721013 咸阳师范学院化学与化工学院陕西咸阳712000

以中学化学课堂实验教学“Fe^(2+)与Fe^(3+)的检验”为例,引导学生先从宏观上观察实验现象,再从微观角度解释实验现象,最后从化学特有的语言—书写“离子反应方程式”进行符号表征。这种“宏-微-符”三重表征法有利于学生学习化学知识... 详细信息

以中学化学课堂实验教学“Fe^(2+)与Fe^(3+)的检验”为例,引导学生先从宏观上观察实验现象,再从微观角度解释实验现象,最后从化学特有的语言—书写“离子反应方程式”进行符号表征。这种“宏-微-符”三重表征法有利于学生学习化学知识和构建三者内在的联系,并培养形成学生化学实验探究学习的特定思维模型。

关键词：宏观微观符号三重表征化学实验