检索结果-南通市图书馆

Lidar observation campaigns on diurnal variations of the sodium layer in Beijing and Wuhan, China

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2015年第8期58卷 1377-1386页

作者： GONG ShaoHua YANG GuoTao cheng xuewu GONG Shun Sheng XU JiYao LI FaQuan GONG Wei WANG JiHong School of Physics and Electronics Engineering Hainan Normal University State Key Laboratory of Space Weather National Space Science Center Chinese Academy of Sciences Laboratory of Optoelectronics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan University

Based on observations from daytime lidars in eastern China,diurnal cycles of the sodium layer over Wuhan(30.5°N,114.6°E)and Beijing(40.5°N,116°E)are *** variations of Na density,root mean square(RMS)layer width,and centroid height of the sodium layer are *** reveal that the large diurnal cycles of the sodium layer are controlled mainly by 24-hr oscillations at the two observation *** diurnal variation of the sodium layer over Wuhan was modulated mainly by tidal perturbations during the lidar observation ***,the diurnal variation over Beijing was controlled principally by photoionization and photochemistry effects during another campaign,and there was little evidence of direct tidal *** comparisons suggest that the diurnal variation of the sodium layer perhaps has obvious regional characteristics across *** variation can be either controlled mainly by tidal perturbations or by photoionization and photochemistry effects in different seasons.

关键词： daytime lidar diurnal variations of the sodium layer photochemistry effects tidal perturbations

Autonomous navigation method and technology implementation of high-precision solar spectral velocity measurement

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2022年第8期65卷 37-44页

作者： Wei Zhang Yong Yang Wei You JinZhou Zheng Hui Ye KaiJun Ji Xiao Chen Xin Lin QingLong Huang xuewu cheng Wei Zhang FaQuan Li Shanghai Academy of Spaceflight Technology Shanghai 201109China Shanghai Institute of Satellite Engineering Shanghai 201109China Shanghai Key Laboratory of Deep Space Exploration Technology Shanghai 201109China State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and MathematicsInnovation Academy of Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China

The velocity information of spacecraft can be directly obtained by the autonomous navigation method based on astronomical spectral velocity measurement. It provides complete direct velocity measurement information for the traditional navigation methods represented by astronomical angle measurement and astronomical ranging, which is of great significance for spacecraft high precision autonomous navigation. This paper comprehensively introduces the principle and navigation method of astronomical spectral velocity measurement, as well as the technical realization of the solar atomic frequency discriminator for autonomous navigation(SAFDAN) based on atomic frequency discrimination velocity measurement. The new SAFDAN is the first instrument to measure the Doppler velocity of spacecraft relative to the Sun. Carried by the CHASE mission, the in-orbit experiment of the SAFDAN is realized, and the in-orbit velocity measurement accuracy reaches 1.93 m/s, which effectively verifies the feasibility of the astronomical spectral velocity measurement method and technology.

关键词： orbit determination and improvement spectra frequency measurement

Daytime observation technology of a lidar using an atomic filter

在线全文

学校读者我要写书评

暂无评论

Frontiers of Optoelectronics 2008年第Z2期1卷 274-278页

作者： xuewu cheng Shunsheng GONG Faquan LI Yang DAI Juan SONG Jiamin WANG Fengyan LI State Key Laboratory of Magnetic Resonance and Molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences

Based on the dual-wavelength high altitude detecting lidar we developed, daytime observation capability was realized in its sodium fluorescence channel by employing a Na(sodium) atomic filter and other relevant technologies. Because of the very narrow passband and very high out-of-band suppression of the Na atomic filter, the lidar echo at an 80–110 km altitude can be obtained even at noontime when background light from the sun is very strong. The capability for a 24-h continuous observation of the lidar system has been demonstrated by the preliminary observation result. This development makes the constant detection and investigation of high altitude atmosphere over the country possible.

关键词： lidar daytime observation Na (sodium) fluorescence atomic filter atomic frequency stabilization

Joint observations of sporadic sodium and sporadic E layers at middle and low latitudes in China

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2014年第29期59卷 3868-3876页

作者： Jing Jiao Guotao Yang Xu Zou Shaohua Gong Jihong Wang Dawei Tian Wenzhen Zhang Tiemin Zhang Xianchang Yang Jun Fu xuewu cheng State Key Laboratory of Space Weather National Space Science CenterChinese Academy of Sciences School of Physics and Electronics Engineering Hainan Normal University Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences

Sporadic sodium layers(SSLs)were studied with sodium(Na)lidar at Beijing(40.5°N,116.0°E)and Haikou(19.5°N,109.1°E)in *** altitude distribution,strength factors,and occurrence time of SSL and sporadic E(Es)layer events were statistically analyzed at both observing *** occurrence had a maximum near22:00 local time,and Eslayer occurrence had a maximum before *** altitude distributions of SSL and Es layer events were better correlated at Haikou than at *** the average values of height and strength factor for SSL and Eslayer events,as well as the average of the maximum frequency that can be reflected by the Eslayer(foEs),at Beijing were higher than those at Haikou.A better correlation between SSL and Eslayer events was also found at Haikou,and the formation of SSLs was considered to likely depend on the seasonal variability of chemical and dynamical processes.

关键词：低纬度地区钠层中国 E层分散观测发生时间强度因子

泥水平衡盾构隧道下穿海河引起河底沉降的数值分析

在线全文

学校读者我要写书评

暂无评论

铁道建筑 2018年第10期58卷 51-54页

作者：程学武北京铁路局地下直径线工程建设指挥部北京100005

以天津地下直径线泥水平衡盾构隧道下穿海河为工程背景,采用有限元软件建立数值计算模型,对河底加固前后盾构隧道下穿海河引起的沉降进行了数值分析。结果表明:盾构隧道下穿海河过程中隧道上覆土层沉降沿横向近似呈正态分布,盾构施工横... 详细信息

以天津地下直径线泥水平衡盾构隧道下穿海河为工程背景,采用有限元软件建立数值计算模型,对河底加固前后盾构隧道下穿海河引起的沉降进行了数值分析。结果表明:盾构隧道下穿海河过程中隧道上覆土层沉降沿横向近似呈正态分布,盾构施工横向影响范围为30 m;隧道上覆土层沿纵向的沉降可划分为盾构接近、盾构下穿和盾构离开3个阶段;河底采取注浆加固措施可以有效控制上覆土层的沉降。现场实施效果表明该注浆加固措施切实可行。

关键词：城市地铁沉降规律数值计算泥水平衡盾构地表变形

在线全文

学校读者我要写书评

暂无评论

高速铁路桥台桩基补强注浆工艺及效果分析

铁道建筑 2020年第12期60卷 38-42页

作者：程学武中国铁路北京局集团有限公司北京100860

以一高速铁路桥台桩基补强工程为依托,结合现场实际情况,采用多次控制劈裂注浆工艺,建立了第1次常压注浆、第2次劈裂注浆、第3次复压注浆工法,分析了钻孔注浆期间周边地面沉降变形,探讨了多次控制劈裂注浆工艺对地面点竖向变形的影响。... 详细信息

以一高速铁路桥台桩基补强工程为依托,结合现场实际情况,采用多次控制劈裂注浆工艺,建立了第1次常压注浆、第2次劈裂注浆、第3次复压注浆工法,分析了钻孔注浆期间周边地面沉降变形,探讨了多次控制劈裂注浆工艺对地面点竖向变形的影响。结合钻孔取芯得到的注浆体样本,研究多次控制劈裂注浆工艺的注浆效果。结果表明:注浆区域与未注浆区域有明显的分界面,注浆后土体的单轴抗压强度变化不大,且不同土性对注浆后土体单轴抗压强度影响较小,注浆补强效果显著。

关键词：高速铁路桩基补强劈裂注浆钻孔取芯注浆工艺

在线全文

学校读者我要写书评

暂无评论

一种消除可调谐激光器空回误差的方法

光学学报 2014年第9期34卷 161-169页

作者：相成志龚威马昕程学武武汉大学测绘遥感信息工程国家重点实验室湖北武汉430079 中科院武汉物理与数学研究所湖北武汉430071

高精度的激光雷达探测对发射波长的精确定标和稳定有极其严格的要求,可调谐激光器进行多次波长调节时存在的激光器空回问题会严重影响系统的探测精度。为此,提出了一种解决可调谐激光器空回问题的算法,得出了通过来回跳转使正负误差相... 详细信息

高精度的激光雷达探测对发射波长的精确定标和稳定有极其严格的要求,可调谐激光器进行多次波长调节时存在的激光器空回问题会严重影响系统的探测精度。为此,提出了一种解决可调谐激光器空回问题的算法,得出了通过来回跳转使正负误差相抵消以消除空回误差的方法,并首先将其应用到大气CO2浓度垂直廓线高精度探测中的稳频部分。通过多次实验表明,该算法提高了可调谐激光器的激光波长调节精度,消除了激光器多次反转调节波长时空回误差对测量精度的影响,弥补了机械转动进行波长调节的不足,对高光谱激光技术的发展有十分重要的意义。

关键词：遥感激光雷达可调谐激光器空回误差稳频高光谱技术

在线全文

学校读者我要写书评

暂无评论

地基激光雷达对大气金属层的探测研究

光学学报 2023年第18期43卷 30-46页

作者：荀宇畅程学武杨国韬太原理工大学物理学院山西太原030024 中国科学院国家空间科学中心北京100190 中国科学院精密测量科学与技术创新研究院湖北武汉430071

中层顶区域(80~110 km)的大气探测具有重要的科研和应用价值。长期以来,由于传统探测手段的限制,该区域一直是人类了解相对较少的大气层区域,存在着由流星注入产生的大气金属层。由于金属原子、离子共振荧光散射的散射截面比瑞利散射、... 详细信息

中层顶区域(80~110 km)的大气探测具有重要的科研和应用价值。长期以来,由于传统探测手段的限制,该区域一直是人类了解相对较少的大气层区域,存在着由流星注入产生的大气金属层。由于金属原子、离子共振荧光散射的散射截面比瑞利散射、拉曼散射大得多,其可以被激光雷达探测到。半个世纪以来,利用原子、离子特定波长的跃迁光谱,向高空大气发射特定波长的激光,并结合遥感技术,开展了大气金属层探测,这些金属原子、离子是大气波动极好的示踪物,可获得大气原子数密度、温度、风场等参量。近年来,随着热层金属层不断被发现,大气金属层的高度范围逐渐拓展,金属层研究又受到人们的极大关注。本文以作者团队及合作者的工作为基础,以大气金属层激光雷达采用的激光器发展历程为主线,介绍了地基激光雷达对大气金属层探测研究的发展过程以及国内外研究现状与发展趋势。

关键词：激光雷达染料激光器 OPO激光器和频技术窄带滤光

基于CCD图像智能分析的激光主动规避飞行物系统

在线全文

学校读者我要写书评

暂无评论

红外与激光工程 2016年第B5期45卷 65-70页

作者：熊俊夏媛杨勇程学武李发泉中国科学院武汉物理与数学研究所波谱与原子分子物理国家重点实验室湖北武汉430071 中国科学院大学北京100049

激光雷达是地球大气探测的有利工具,但其向空中发射的强激光束会对空域飞行物存在潜在威胁。为保障激光雷达上空飞行物的飞行安全,提出了一种基于CCD成像探测的激光智能主动规避飞行物的方法,并搭建了一套实验装置。该装置通过触发同步... 详细信息

激光雷达是地球大气探测的有利工具,但其向空中发射的强激光束会对空域飞行物存在潜在威胁。为保障激光雷达上空飞行物的飞行安全,提出了一种基于CCD成像探测的激光智能主动规避飞行物的方法,并搭建了一套实验装置。该装置通过触发同步控制CCD实时采集激光雷达激光束方向一定范围的空域图像,再对图像进行降噪、差值和二值化等处理,并判断是否有飞行物在空域范围内,根据处理结果控制激光发射光路中的机械开关打开或者关闭,有效保证了激光雷达的安全运行以及飞行物的安全。

关键词：飞行物规避激光雷达图像采集 CCD