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Determination of the free lunar libration modes from ephemeris DE430 被引量:2
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作者 Yong-Zhang Yang Jin-Ling Li +1 位作者 Jin-Song Ping Hideo Hanada 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2017年第12期89-94,共6页
The Moon’s physical librations have been extensively studied, and elaborate researches have been developed for the purpose of deriving accurate modes of free librations. Our motivation comes from the Planetary and Lu... The Moon’s physical librations have been extensively studied, and elaborate researches have been developed for the purpose of deriving accurate modes of free librations. Our motivation comes from the Planetary and Lunar Ephemeris DE430 by JPL/NASA, which was created in April 2013,and is reported to be the most accurate lunar ephemeris today using the data from Gravity Recovery and Interior Laboratory(GRAIL). Therefore, the residuals after fitting the model have reduced owing to improvement in the libration models, and the free librations embedded in the Euler angles have also improved. We use Fourier analysis to extract the approximate frequencies from DE430 and then a quadratic interpolation method is used to determine higher accuracy frequencies. With the frequencies,the linear least-squares fitting method is employed to fit the lunar physical librations to DE430. From this analysis we identified the three modes of free physical librations, and estimated the amplitudes as 1.471′′in longitude, 0.025′′in latitude and 8.19′′× 3.31′′for the wobble, with the respective periods of1056.16, 8806.9 and 27262.99 d. Since the free librations damp with time, they require recent excitation or a continuous stimulating mechanism in order to sustain. 展开更多
关键词 MOON physical librations Fourier analysis least squares method
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Attitude dynamics in the circular restricted three-body problem
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作者 Davide Guzzetti Kathleen Connor Howell 《Astrodynamics》 2018年第2期87-119,共33页
This document reflects the effort of constructing a basis for understanding attitude motion within a multi-body problem with application to spacecraft flight dynamics.The circular restricted three-body problem(CR3BP)i... This document reflects the effort of constructing a basis for understanding attitude motion within a multi-body problem with application to spacecraft flight dynamics.The circular restricted three-body problem(CR3BP)is employed as a model for the orbital motion.Then,attitude dynamics is discussed within the CR3BP.Conditions for bounded attitude librations and techniques for the identification of such behavior are presented:initially for a spacecraft fixed at an orbital equilibrium point,and later for a vehicle that moves on non-linear periodic orbit.While previous works focus on specific challenges,this analysis serves to create a more general framework for attitude dynamics within the CR3BP.A larger framework enables additional observations.For example,a linkage is noted between regions of bounded motion that may appear on an attitude grid search map and families of periodic attitude solutions.Finally,coupling effects between attitude and orbit dynamics within the CR3BP,ones that enable new options for trajectory design,are considered an important opportunity,and should be included in a general framework.As a proof of that concept,sailcraft trajectories are generated within a coupled orbit-attitude model only using a sequence of constant commands for the attitude actuators. 展开更多
关键词 three-body problem orbit-attitude dynamics bounded attitude librations turn and hold model
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高速切削机床横梁的静态与动态分析 被引量:32
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作者 侯红玲 邱志惠 赵永强 《机械设计与制造》 北大核心 2006年第5期38-39,共2页
在机床设计的初期,利用有限元分析软件ANSYS,在材料和截面空间尺寸相似的情况下,对截面形状不同的几种结构的梁进行静力和模态分析,将强度较好的梁,用模态分析得到刚度更好的梁。通过结构的变形和一阶频率的振型研究比较,初步确定了较... 在机床设计的初期,利用有限元分析软件ANSYS,在材料和截面空间尺寸相似的情况下,对截面形状不同的几种结构的梁进行静力和模态分析,将强度较好的梁,用模态分析得到刚度更好的梁。通过结构的变形和一阶频率的振型研究比较,初步确定了较为合理的横梁结构。 展开更多
关键词 截面形状 强度 刚度 模态分析 振动模态相对位移量
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双层结构月球的自由天平动与受迫天平动 被引量:3
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作者 李文潇 Alexander GUSEV +1 位作者 平劲松 张同杰 《深空探测学报》 2014年第3期205-209,共5页
根据JPL/NASA发布的月球行星历表DE430/LE430提供的月球物理参数,计算了月球主转动惯量;使用刚体月球转动微分方程获得的月球物理天平动解析关系式,计算了不同分层模型的月球自由天平动三个模式的频率及周期,比较并讨论了不同的解析结果... 根据JPL/NASA发布的月球行星历表DE430/LE430提供的月球物理参数,计算了月球主转动惯量;使用刚体月球转动微分方程获得的月球物理天平动解析关系式,计算了不同分层模型的月球自由天平动三个模式的频率及周期,比较并讨论了不同的解析结果;在此基础上,评估了月球受迫天平动一个模式的幅度。 展开更多
关键词 月球天平动 解析方法 频率及周期 幅值
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船舶轴系扭振的消减与回避 被引量:2
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作者 唐军 蒋德志 《青岛远洋船员学院学报》 2004年第2期25-27,35,共4页
柴油机轴系的扭转振动是引起柴油机动力装置故障的重要原因之一,本文利用振动力学的知识,结合实例分析,对扭振的消减和回避进行了探讨。
关键词 扭转振动 扭振应力 扭振能量 共振
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PSD在汽轮机轴承振动测量中的研究
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作者 高经伍 褚海波 赵凤华 《汽轮机技术》 北大核心 2009年第1期67-69,共3页
介绍了一种测量汽轮机轴承振动的新方法。它是在汽轮机轴承的垂直、水平和轴向3个位置的表面各贴一个反光物质,当激光器发出的光线照射在反光物质并反射到某个平面上两个相互垂直的敏感传感器(简称PSD)时,从PSD传感器的检测电路就能输... 介绍了一种测量汽轮机轴承振动的新方法。它是在汽轮机轴承的垂直、水平和轴向3个位置的表面各贴一个反光物质,当激光器发出的光线照射在反光物质并反射到某个平面上两个相互垂直的敏感传感器(简称PSD)时,从PSD传感器的检测电路就能输出轴承表面的振动波形,然后利用比较器从3个方向的振动位移选取一个最大值,当最大值超过汽轮机的轴承位移的规定值时,汽轮机跳闸停机并报警。另外,还着重介绍了PSD的测量原理、检测电路等。最后介绍了利用PSD测量汽轮机的轴承振动的优点,这为以后研究汽轮机轴承振动的测量提供了一种新的思路。 展开更多
关键词 位置敏感传感器 汽轮机 轴承振动 测量
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基于数值历表的月球物理天平动研究
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作者 黄凯 孙尚彪 +2 位作者 杨永章 李祝莲 李语强 《天文研究与技术》 CSCD 2022年第4期326-332,共7页
月球物理天平动是月球运动在空间的描述。确定月球物理天平动,可以推测物理天平动的激发与耗散机制,比如陨击、月震和核幔粘滞摩擦等,测定月球物理天平动对认识太阳系天体的起源、演化及结构等具有十分重要的意义。利用最新的INPOP19a... 月球物理天平动是月球运动在空间的描述。确定月球物理天平动,可以推测物理天平动的激发与耗散机制,比如陨击、月震和核幔粘滞摩擦等,测定月球物理天平动对认识太阳系天体的起源、演化及结构等具有十分重要的意义。利用最新的INPOP19a历表数据,完成了对从历表提取的欧拉角到月球物理天平动的转换,得到的物理天平动数值分别与该系列历表INPOP17a以及DE430对比发现,不同历表的物理天平动之差存在稳定的周期。对比历表欧拉角的差别,计算出地心到月面反射器A15的距离最大有30 cm的差别,此结果对月球激光测距的预报精度有较大的影响,为后续高精度测月研究打下基础。研究结果表明,INPOP19a最为稳定,在月球物理天平动研究中推荐使用INPOP19a。 展开更多
关键词 月球历表 欧拉角 月球天平动 傅里叶变换
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齿轮噪声之探究 被引量:12
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作者 韩香丽 《山西机械》 2001年第3期28-30,共3页
基于机械噪声的危害 ,找出并分析了形成齿轮噪声的各种原因和机理 。
关键词 齿轮 噪声 振动
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An overview of the mission and technical characteristics of Change'4 Lunar Probe 被引量:11
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作者 YE PeiJian SUN ZeZhou +1 位作者 ZHANG He LI Fei 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2017年第5期658-667,共10页
Change'4 Lunar Probe will softly land on the farside of the Moon for the first time of all mankind and carry out in-situ and rovering exploration. In this paper, the scientific significance and engineering difficulti... Change'4 Lunar Probe will softly land on the farside of the Moon for the first time of all mankind and carry out in-situ and rovering exploration. In this paper, the scientific significance and engineering difficulties of Change'4 are introduced and the probe's general design, including the aspects of landing site selection, relay communication, trajectory design of relay satellite is explained. Besides, four key technologies, namely safe landing strategy on complex terrain, orbit design and control of libration point 2, relay communication on L2, radioisotope thermoelectric generator (RTG) and electric-thermal utilization, as well as how to realize them are also discussed. Finally the prospect of the prominent technological breakthrough of Change'4 is described. 展开更多
关键词 Change'4 farside relay communication libration point South-Pole Aitken Basin RTG
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Trajectory and Correction Maneuver During the Transfer from Earth to Halo Orbit 被引量:8
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作者 徐明 徐世杰 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2008年第3期200-206,共7页
This article addresses the design of the trajectory transferring from Earth to Halo orbit, and proposes a timing closed-loop strategy of correction maneuver during the transfer in the frame of circular restricted thre... This article addresses the design of the trajectory transferring from Earth to Halo orbit, and proposes a timing closed-loop strategy of correction maneuver during the transfer in the frame of circular restricted three body problem (CR3BP). The relation between the Floquet multipliers and the magnitudes of Halo orbit is established, so that the suitable magnitude for the aerospace mission is chosen in terms of the stability of Halo orbit. The stable manifold is investigated from the Poincar6 mapping defined which is different from the previous researches, and six types of single-impulse transfer trajectories are attained from the geometry of the invariant manifolds. Based on one of the trajectories of indirect transfer which are ignored in the most of literatures, the stochastic control theory for imperfect information of the discrete linear stochastic system is applied to design the trajectory correction maneuver. The statistical dispersion analysis is performed by Monte-Carlo simulation, 展开更多
关键词 libration point Halo orbit orbit design trajectory correction maneuver stochastic control theory Monte-Carlo simulation
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浅析三相交流异步电动机常见故障及维护 被引量:10
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作者 李元 《山西建筑》 2009年第10期349-350,共2页
结合生产运行和检修实践,分析了三相交流异步电动机常见故障产生的原因,并提出了具体的处理方法,以提高人们对三相交流异步电动机的认识,确保电动机安全可靠的运行。
关键词 三相交流异步电动机 轴承 振动 缺相运行
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滚珠丝杠副综合性能动态测量系统设计 被引量:9
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作者 周超 殷爱华 冯虎田 《机械设计与制造》 北大核心 2012年第4期32-34,共3页
介绍了滚珠丝杠副综合性能动态测试系统设计,根据测试系统技术要求,确定了测试系统总体方案,对系统的机械结构及电气组成进行了设计,确定了试验条件及测量方法,开发了系统测试软件。构建的测试系统可以动态实时测量滚珠丝杠副在四种安... 介绍了滚珠丝杠副综合性能动态测试系统设计,根据测试系统技术要求,确定了测试系统总体方案,对系统的机械结构及电气组成进行了设计,确定了试验条件及测量方法,开发了系统测试软件。构建的测试系统可以动态实时测量滚珠丝杠副在四种安装方式下振动、噪声、温升、极限转速等性能。通过试验及试验数据采集与分析,根据HJS056动态测量的滚珠丝杠副噪声、振动、温升、极限转速等性能测试结果,取得了四种安装方式下滚珠丝杠副性能试验结论,为滚珠丝杠副的优化设计提供实验数据。 展开更多
关键词 滚珠丝杠副 动态测量 四种支承方式 噪声 振动 温升
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薄膜二维振动数理方程的推导与求解 被引量:7
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作者 张俊生 《榆林学院学报》 2006年第6期29-31,共3页
偏微分方程经常出现在物理学、工程技术和其它科学的许多分支中。在现行的数学物理方法教材中,数理方程只涉及到一维的弦振动方程、杆振动方程和热传导方程等,对二维薄膜的振动只作了扼要的介绍。试图对薄膜振动方程加以推导和求解。
关键词 薄膜 振动 微分方程 推导 求解
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基于JPL星历的月基SAR多普勒参数估算方法 被引量:7
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作者 丁翼星 郭华东 刘广 《北京航空航天大学学报》 EI CAS CSCD 北大核心 2015年第1期71-76,共6页
月基合成孔径雷达(SAR)与传统低轨SAR相比,成像几何上存在成像距离长的特点,其多普勒参数估计方法也不同于常规的机载和星载SAR.基于喷气推进实验室(JPL)高精度星历,可以通过插值获取月心在地心惯性坐标系下的位置、速度和加速度以及月... 月基合成孔径雷达(SAR)与传统低轨SAR相比,成像几何上存在成像距离长的特点,其多普勒参数估计方法也不同于常规的机载和星载SAR.基于喷气推进实验室(JPL)高精度星历,可以通过插值获取月心在地心惯性坐标系下的位置、速度和加速度以及月球天平动,然后经由坐标转换得到月面任意位置在地心惯性坐标系下的位置、速度和加速度.在此基础上,建立了两个二次方程组,第1个方程组的解表示任意星下点离线角和斜视角情况下的波束矢量,第2个方程组求得波束矢量的模值,以此解算地面波束中心的坐标.结果表明,月基SAR的波束角需沿轨不断调整,而且天线放置的位置也会对多普勒参数产生明显影响. 展开更多
关键词 月基SAR 多普勒参数 JPL星历 月基对地观测 天平动
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某轮主机燃油管路振动分析及对策 被引量:6
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作者 刘彦辉 黄玉学 胡龙军 《舰船科学技术》 2010年第9期47-50,共4页
简要介绍了某轮在试航以及交付使用后,主机燃油管系振动剧烈,频繁出现马脚断裂、马脚螺栓断裂、燃油管路漏油等故障。简要阐述了燃油管系振动故障造成的危害,详细分析了引起管系振动的原因,并对管路的振动性能参数进行了现场测量,采取... 简要介绍了某轮在试航以及交付使用后,主机燃油管系振动剧烈,频繁出现马脚断裂、马脚螺栓断裂、燃油管路漏油等故障。简要阐述了燃油管系振动故障造成的危害,详细分析了引起管系振动的原因,并对管路的振动性能参数进行了现场测量,采取相应措施改造了管路,对改造后的管路振动性能参数再次进行了测量,管路振动幅度明显减小,验证了管路改造的效果。 展开更多
关键词 船舶 燃油管路 振动 原因分析 改造措施
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电动机振动的分析 被引量:5
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作者 胡新晚 杨益梅 《微电机》 2003年第2期57-58,62,共3页
转子的机械不平衡及安装、连接不良是造成电机振动的一个主要因素 ,文中详细介绍了在生产过程中引起转子动平衡不合格的主要原因及解决的基本对策方法。
关键词 电动机 振动 转子 轴承 直流电动机
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Autonomous navigation to quasi-periodic orbits near translunar libration points 被引量:3
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作者 Jing Wuxing Qian Yingjing +1 位作者 Gao Changsheng Li Jianqing 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2013年第5期1259-1268,共10页
Libration-point missions have been very useful and successful. Due to the unstable natures of most of these orbits, the long-time stationkeeping demands frequent maneuvers and precise orbit determinations. Earth-based... Libration-point missions have been very useful and successful. Due to the unstable natures of most of these orbits, the long-time stationkeeping demands frequent maneuvers and precise orbit determinations. Earth-based tracking will have to undertake much more responsibilities with the increasing number of libration missions. An autonomous navigation system could offer a better way to decrease the need for Earth-based tracking. Nevertheless, when an autonomous navigation system is applied, there are three important factors affecting autonomous navigation accuracy, i.e., the accuracy of initial conditions, the accuracy of measurements, and the accuracy of onboard dynamics for propagation. This paper focuses on analyzing the influence from the third factor and finding an appropriate navigation dynamics, which can satisfy the requirement of estimation accuracy but not cause too much burden for onboard computation. When considering the restricted three-body model and the bicircular restricted four-body model as navigation dynamics, the astrin- gency is not shown during the simulations. Meanwhile, when considering the influences of the Sun's direct and indirect perturbations and the eccentricity of the Moon's orbit, a new navigation dynamic model with the standard ephemerides is proposed. The simulation shows the feasibility of the proposed model. 展开更多
关键词 Autonomous navigation Extended Kalman filters libration points Multi-body dynamics Quasi-periodic orbit
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Scheme design of the CHANG'E-5T1 extended mission 被引量:3
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作者 Lei LIU Chunyang HU 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2018年第7期1559-1567,共9页
Flight schemes for the CHANG'E-5T1 extended mission are investigated in this paper.In the flight scheme and trajectory design, the remaining propellant of the CHANG'E-5T1 mission is utilized. The CHANG'E-5T1 missio... Flight schemes for the CHANG'E-5T1 extended mission are investigated in this paper.In the flight scheme and trajectory design, the remaining propellant of the CHANG'E-5T1 mission is utilized. The CHANG'E-5T1 mission is firstly introduced with feasible flight goals derived based on the terminal trajectory and satellite status. The flight schemes are designed to include a lunar return and the libration points in the Sun-Earth/Moon and Earth-Moon systems, with an emphasis on the Earth-Moon triangle libration point thus far unexplored. Secondly, three schemes are proposed for the CHANG'E-5T1 extended mission with different flight goals. The direct libration point orbit transfer and injection method is adopted to solve the issue in the transfer trajectory design.Furthermore, an innovative concept is proposed to transfer from the Earth-Moon collinear libration point to the triangle point using the Sun-Earth/Moon libration point. Finally, the merits and drawbacks of the three schemes are discussed in terms of flight time, control energy and frequency, flight distance, and goal value. As a result, the scheme including a lunar return and the Earth-Moon L2 libration point is selected for the CHANG'E-5T1 extended mission. A flight to the Earth-Moon libration point is achieved, replicating the achievement of the ARTEMIS mission. 展开更多
关键词 CHANG'E-5T1 mission Extended mission Flight scheme libration point Lunar exploration Trajectory design
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我国噪声与振动控制行业2013年发展综述 被引量:5
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作者 Noise and Libration Control Committee of CAEPI 《中国环保产业》 2014年第12期25-35,共11页
综述了2012年我国噪声与振动控制行业的发展环境以及行业的生产经营情况;阐述了行业总体技术进展、新技术的开发应用概况,以及行业市场特点及重要动态;分析了行业主要骨干企业的发展情况及企业的国内外竞争力状况;针对行业发展中存在的... 综述了2012年我国噪声与振动控制行业的发展环境以及行业的生产经营情况;阐述了行业总体技术进展、新技术的开发应用概况,以及行业市场特点及重要动态;分析了行业主要骨干企业的发展情况及企业的国内外竞争力状况;针对行业发展中存在的主要问题,提出了解决对策和建议,并对行业的发展进行了展望。 展开更多
关键词 噪声 振动 控制 市场 骨干企业 行业发展
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An improved nonlinear control strategy for deep space formation flying spacecraft 被引量:2
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作者 Peng Li Pingyuan Cui Hutao Cui Deep Space Exploration Research Center,Harbin Institute of Technology, 150080 Harbin, China 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2009年第6期847-856,共10页
This paper aims to provide further study on the nonlinear modeling and controller design of formation flying spacecraft in deep space missions. First, in the Sun-Earth system, the nonlinear formation dynamics for the ... This paper aims to provide further study on the nonlinear modeling and controller design of formation flying spacecraft in deep space missions. First, in the Sun-Earth system, the nonlinear formation dynamics for the circular restricted three-body problem (CRTBP) and elliptic restricted three-body problem (ERTBP) are presented. Then, with the Floquet mode method, an impulsive controller is developed to keep the Chief on the desired Halo orbit. Finally, a nonlinear adaptive control scheme based on Nonzero set- point LQR and neural network is proposed to achieve high precision formation maneuver and keeping. The simulation results indicate that the proposed nonlinear control strategy is reasonable as it considers not only the orbit keeping of the Chief, but also the formation modeling inaccuracy. Moreover, the nonlinear adaptive control scheme is effective to improve the control accuracy of the formation keeping. 展开更多
关键词 Spacecraft formation flying. libration pointHalo orbit - Nonlinear control
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