共查询到20条相似文献,搜索用时 656 毫秒
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本文从列车器件测量精度的估计公式出发,推出导了用低精度A/D变换器伯获得高精度测量结果的一般性证明,还讨论了这种方法的若干可能应用。 相似文献
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当用CCD和Reticon等列阵器件观测恒星时,可利用每个象素的光度读数提供的信息,求出星像的光度重心作为星像的中心。本文应用概率与数理统计知识阐述了重心法测量星像位置时的精度估计,得出测量的精度与星像的象素的总光度读数的平方根成反比的结论。 相似文献
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CCD图像的二维修正矩定心方法 总被引:3,自引:0,他引:3
对于天体测量而言,CCD图像的数字星像处理方法是十分重要的.本文根据CCD器件的特性,从理论上推导了二维修正矩算法的最佳门限取值方法.通过处理模拟和实测数据,与传统的二维高斯拟合法比较,在保持矩方法简便特性的同时,在精度上亦有所提高,对于暗星效果更为明显. 相似文献
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讲述了同步广播卫星电视时间信号的测量方法和测量结果,获得了CCTV1、CCTV2通过同一颗卫星(亚太-1A)转播的时延差值为16333μs,测量精度在10ns以内;CCTV2、CCTV4分别经两颗卫星(亚太-1A、亚洲-Ⅱ)转播,在陕西天文台卫星地面接收站时延差值为1644.20μs,精度为50μs,并分析了影响时延差值和精度的原因。同时测量了地方电视台转播亚太-1A的CCTV信号与直接接收亚太-1A的CCTV信号的时延差值,其测量精度为0.1μs。这些结果为利用同步广播卫星的电视信号进行高精度的时间服务提供了参考依据。 相似文献
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本文介绍了低纬子午环上电水准器的工作原理;讨论了电水准器在测定定位盘上盘的水平差时,其Deticon的比例尺的测定方法及其测量精度;讨论了电水准器中狭缝倾斜量的测量方法;最后给出了水平差的测量范围以及可达到的精度,证明低纬子午环对轴系的要求是比较低的,而水平差的测量精度是相当高的。 相似文献
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GDJ打印经纬仪技术改造 总被引:1,自引:1,他引:0
本项改造提高了脱靶量的测量精度和减小了轴系的系统偏差,从而提高卫星的空间定位精度,为空间目标高精度测轨预报和方法研究了提供了测量手段。 相似文献
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介绍一种天线口面温度定标的方法.当用这个方法对目标源进行温度定标时,由于定标源讯号和目标源讯号均由天线口面同路输入,因此波导和微波器件的传输损耗在定标的过程中被自动消除,因而这种温度定标方法能大大地提高观测资料的精度.目前无线口面温度定标方法除了在射电天文和微波天线测量中应用外,还广泛应用于雷达和无线电技术测量及微波遥感控制等. 相似文献
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介绍一种天线口面温度定标的方法,当用这个方法对目标源进行温度定标时,由于定标源讯号和目标源讯号均由天线口面同路输入,因此波导和微波器件的传输损耗在定标的过程中被自动消除,因而这种温度定标方法能大大地提高观测资料的精度。目前天线口面温度定标方法除了在射电天和微波天线测量中应用外,还广泛应用于雷达和无线电技术测量及微波遥感控制等。 相似文献
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《天文和天体物理学研究(英文版)》2016,(8)
In this paper, a cascade acceleration feedback control(AFC) enhanced by a disturbance observation and compensation(DOC) method is proposed to improve the tracking precision of telescope systems.Telescope systems usually suffer some uncertain disturbances, such as wind load, nonlinear friction and other unknown disturbances. To ensure tracking precision, an acceleration feedback loop which can increase the stiffness of such a system is introduced. Moreover, to further improve the tracking precision, we introduce the DOC method which can accurately estimate the disturbance and compensate it. Furthermore,the analysis of tracking accuracy used by this method is proposed. Finally, a few comparative experimental results show that the proposed control method has excellent performance for reducing the tracking error of a telescope system. 相似文献
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高精度全球定位系统(Global Positioning System,GPS)数据处理的成果精度往往受海潮模型、卫星轨道约束模式、星历产品等数据类型及处理策略的制约。在考虑上述影响因素的前提下进行相关实验,并基于误差理论提出一种增加基线解算次数组合平差的方法,以提高基线解算精度。实验结果表明,数据处理中置入海潮模型较未采用前精度更高,FES2004模型的内外符合精度整体最优,近海区NAO99b外符合精度占优,其它海潮模型基本相当;松弛轨道模式内符合精度较固定轨道模式内符合精度高,但外符合精度较轨道固定模式稍差。不同的精密轨道产品对最终解算结果影响较小,增加基线解算次数组合平差的方法对数据处理成果精度的提高具有明显效果,且在几种精密星历下均表现出良好的收敛性。 相似文献
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A method of realtime autonomous orbit determination for earth satellites using the extended Kalman filtering is proposed. The observed quantities are: the satellite-sun direction vector measured by a sun sensor, the satellite-earth and satellite-moon direction vectors measured by an ultraviolet sensor, and the geocentric distance measured by a radar altimeter. At the same time the satellite attitude to the earth is also determined. Results of our simulation of the autonomous orbit determination show that the precision of the orbit determinations is better than 200 m. The effects of the sampling period, orbital inclination, orbital eccentricity and orbital altitude on the precision of orbit determination are analyzed and compared, and certain principles helpful for improving the precision of orbit determination are suggested. 相似文献
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Quantitative helioseismology and asteroseismology require very precise measurements of the frequencies, amplitudes, and lifetimes of the global modes of stellar oscillation. The precision of these measurements depends on the total length (T), quality, and completeness of the observations. Except in a few simple cases, the effect of gaps in the data on measurement precision is poorly understood, in particular in Fourier space where the convolution of the observable with the observation window introduces correlations between different frequencies. Here we describe and implement a rather general method to retrieve maximum likelihood estimates of the oscillation parameters, taking into account the proper statistics of the observations. Our fitting method applies in complex Fourier space and exploits the phase information. We consider both solar-like stochastic oscillations and long-lived harmonic oscillations, plus random noise. Using numerical simulations, we demonstrate the existence of cases for which our improved fitting method is less biased and has a greater precision than when the frequency correlations are ignored. This is especially true of low signal-to-noise solar-like oscillations. For example, we discuss a case where the precision of the mode frequency estimate is increased by a factor of five, for a duty cycle of 15%. In the case of long-lived sinusoidal oscillations, a proper treatment of the frequency correlations does not provide any significant improvement; nevertheless, we confirm that the mode frequency can be measured from gapped data with a much better precision than the 1/T Rayleigh resolution. 相似文献
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推导了传统全球卫星导航定位系统(GNSS)测定垂线偏差(Deflection of the Vertical, DOV)形式误差的表达式;提出一种可用以解算并置站DOV的小网参数转换法.利用乌鲁木齐南山多技术并置站控制网观测信息,开展了算法验证,并对该站内多个地点DOV开展了实测.结果表明,高精度的小网DOV仅由点位观测精度最高、覆盖面积最广的3个站点决定.个别精度较差的点会为DOV的测定值带来较大的不确定性;采用小网转换法所解算的DOV与实测值间的一致性分别为-2.3′′±4.3′′(子午分量)和0.2′′±4.6′′(卯酉分量);小网转换求取DOV的方法在精度上与经典的GNSS水准方法相当,但步骤更加简便.鉴于多技术并置站会不定期地开展本地测量,可利用该方法实现多技术并置站DOV的零成本长期监测. 相似文献
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Qiao Wang 《天文和天体物理学研究(英文版)》2021,(1)
We investigate a hybrid numerical algorithm aimed at large-scale cosmological N-body simulation for on-going and future high precision sky surveys.It makes use of a truncated Fast Multiple Method(FMM)for short-range gravity,incorporating a Particle Mesh(PM)method for long-range potential,which is applied to deal with extremely large particle number.In this work,we present a specific strategy to modify a conventional FMM by a Gaussian shaped factor and provide quantitative expressions for the interaction kernels between multipole expansions.Moreover,a proper Multipole Acceptance Criterion for the hybrid method is introduced to solve potential precision loss induced by the truncation.Such procedures reduce the amount of computation compared to an original FMM and decouple the global communication.A simplified version of code is introduced to verify the hybrid algorithm,accuracy and parallel implementation. 相似文献
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《天文和天体物理学研究(英文版)》2017,(12)
In asteroid rendezvous missions, the dynamical environment near an asteroid's surface should be made clear prior to launch of the mission. However, most asteroids have irregular shapes,which lower the efficiency of calculating their gravitational field by adopting the traditional polyhedral method. In this work, we propose a method to partition the space near an asteroid adaptively along three spherical coordinates and use Chebyshev polynomial interpolation to represent the gravitational acceleration in each cell. Moreover, we compare four different interpolation schemes to obtain the best precision with identical initial parameters. An error-adaptive octree division is combined to improve the interpolation precision near the surface. As an example, we take the typical irregularly-shaped nearEarth asteroid 4179 Toutatis to demonstrate the advantage of this method; as a result, we show that the efficiency can be increased by hundreds to thousands of times with our method. Our results indicate that this method can be applicable to other irregularly-shaped asteroids and can greatly improve the evaluation efficiency. 相似文献