Prior to achieving high precision navigation of a spacecraft using X-ray observations, a pulsar rotation model must be built and analysis of the precise posi- tion of the Earth should be performed using ground pulsar ...Prior to achieving high precision navigation of a spacecraft using X-ray observations, a pulsar rotation model must be built and analysis of the precise posi- tion of the Earth should be performed using ground pulsar timing observations. We can simulate time-of-arrival ground observation data close to actual observed values before using pulsar timing observation data. Considering the correlation between the Earth＇s position and its short arc section of an orbit, we use polynomial regression to build the correlation. Regression coefficients can be calculated using the least square method, and a coordinate component series can also be obtained; that is, we can calcu- late Earth＇s position in the Barycentric Celestial Reference System according to pulse arrival time data and a precise pulsar rotation model. In order to set appropriate param- eters before the actual timing observations for Earth positioning, we can calculate the influence of the spatial distribution of pulsars on errors in the positioning result and the influence of error source variation on positioning by simulation. It is significant that the threshold values of the observation and systematic errors can be established before an actual observation occurs; namely, we can determine the observation mode with small errors and reject the observed data with big errors, thus improving the positioning result.展开更多
Objective To explore the efficacy of logistic regression modeling based on plasma amino acid profile and patient age,for diagnosing hepatic fibrosis in patients with chronic hepatitis B (CHB) .Methods One-hundredand-f...Objective To explore the efficacy of logistic regression modeling based on plasma amino acid profile and patient age,for diagnosing hepatic fibrosis in patients with chronic hepatitis B (CHB) .Methods One-hundredand-forty-eight patients (108 males;mean age:38.1±11.9 years,range:16—72 years)展开更多
国土空间是一切经济社会活动的载体,探究其生态效率时空演化特征及影响因素对国土资源可持续利用和区域经济社会高质量发展具有重要意义。基于三区空间视角和多源数据构建国土空间利用生态效率(Territory Use Eco-efficiency, TUEE)测...国土空间是一切经济社会活动的载体,探究其生态效率时空演化特征及影响因素对国土资源可持续利用和区域经济社会高质量发展具有重要意义。基于三区空间视角和多源数据构建国土空间利用生态效率(Territory Use Eco-efficiency, TUEE)测度体系,综合非期望产出Super-SBM模型、空间自相关分析和多尺度地理加权回归(MGWR)定量分析2000~2020年江苏省53个县域单元的TUEE水平、时空差异及驱动因素。结果表明:(1)江苏省TUEE水平呈现逐步提升趋势,城镇空间、生态空间生态效率稳步提升,农业空间生态效率先降低后升高;(2)江苏省TUEE从高水平县域零星分布逐步转为南高北低格局,沿海县域TUEE相较于内陆县域具备一定优势。研究期内,其存在显著空间正相关关系且不断增强,高高集聚分布在苏南县域,低低集聚分布在苏北县域;(3)江苏省TUEE影响因素存在空间异质性,气温、对外开放水平对其有显著促进作用,高程因素对其有显著抑制作用,人口密度和经济发展水平对其有促进作用但不显著。据此,应通过加强县域间联系、因地制宜开展国土空间利用活动、优化产业结构和政府投入等方式,提升江苏省国土空间利用整体生态水平。展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 10973030,10973032,11003039,10903032 and 10973049)the National Science Foundation of Shanghai,China (Grant No. 10ZR1435700)
文摘Prior to achieving high precision navigation of a spacecraft using X-ray observations, a pulsar rotation model must be built and analysis of the precise posi- tion of the Earth should be performed using ground pulsar timing observations. We can simulate time-of-arrival ground observation data close to actual observed values before using pulsar timing observation data. Considering the correlation between the Earth＇s position and its short arc section of an orbit, we use polynomial regression to build the correlation. Regression coefficients can be calculated using the least square method, and a coordinate component series can also be obtained; that is, we can calcu- late Earth＇s position in the Barycentric Celestial Reference System according to pulse arrival time data and a precise pulsar rotation model. In order to set appropriate param- eters before the actual timing observations for Earth positioning, we can calculate the influence of the spatial distribution of pulsars on errors in the positioning result and the influence of error source variation on positioning by simulation. It is significant that the threshold values of the observation and systematic errors can be established before an actual observation occurs; namely, we can determine the observation mode with small errors and reject the observed data with big errors, thus improving the positioning result.
文摘Objective To explore the efficacy of logistic regression modeling based on plasma amino acid profile and patient age,for diagnosing hepatic fibrosis in patients with chronic hepatitis B (CHB) .Methods One-hundredand-forty-eight patients (108 males;mean age:38.1±11.9 years,range:16—72 years)
文摘国土空间是一切经济社会活动的载体,探究其生态效率时空演化特征及影响因素对国土资源可持续利用和区域经济社会高质量发展具有重要意义。基于三区空间视角和多源数据构建国土空间利用生态效率(Territory Use Eco-efficiency, TUEE)测度体系,综合非期望产出Super-SBM模型、空间自相关分析和多尺度地理加权回归(MGWR)定量分析2000~2020年江苏省53个县域单元的TUEE水平、时空差异及驱动因素。结果表明:(1)江苏省TUEE水平呈现逐步提升趋势,城镇空间、生态空间生态效率稳步提升,农业空间生态效率先降低后升高;(2)江苏省TUEE从高水平县域零星分布逐步转为南高北低格局,沿海县域TUEE相较于内陆县域具备一定优势。研究期内,其存在显著空间正相关关系且不断增强,高高集聚分布在苏南县域,低低集聚分布在苏北县域;(3)江苏省TUEE影响因素存在空间异质性,气温、对外开放水平对其有显著促进作用,高程因素对其有显著抑制作用,人口密度和经济发展水平对其有促进作用但不显著。据此,应通过加强县域间联系、因地制宜开展国土空间利用活动、优化产业结构和政府投入等方式,提升江苏省国土空间利用整体生态水平。
