共查询到20条相似文献，搜索用时 15 毫秒
1.
斜轴式望远镜是一种新颖的望远镜结构, 其独特的结构设计更适合南极等极端气候环境, 但目前国内外缺乏针对斜轴式望远镜详细的动力学建模与控制研究. 提出一套斜轴式望远镜动力学建模与鲁棒控制方法, 首先, 对斜轴式望远镜进行了动力学分析, 采用拉格朗日法建立望远镜2自由度刚体模型; 接着, 结合望远镜驱动系统的柔性和所受干扰, 完成了斜轴式望远镜的干扰情况下刚柔耦合系统数学模型的推导; 然后, 针对抗干扰问题, 根据所建数学模型, 设计了基于干扰观测器的滑模控制器, 对于所受干扰进行抑制, 实现了斜轴式望远镜的鲁棒控制; 最后, 仿真结果显示, 在考虑模型的非线性外部干扰的情况下, 相比于传统的比例-积分-微分控制器, 基于干扰观测器的滑模控制器使得系统具有更好的动态性能和抗干扰特性. 相似文献
2.
A new calibration model for pointing a radio telescope that considers nonlinear errors in the azimuth axis 总被引：1，自引：0，他引：1
A new calibration model of a radio telescope that includes pointing error is presented, which considers nonlinear errors in the azimuth axis. For a large radio telescope, in particular for a telescope with a turntable, it is difficult to correct pointing errors using a traditional linear calibration model, because errors produced by the wheel-on-rail or center bearing structures are generally nonlinear. Fourier expansion is made for the oblique error and parameters describing the inclination direction along the azimuth axis based on the linear calibration model, and a new calibration model for pointing is derived. The new pointing model is applied to the 40 m radio telescope administered by Yunnan Observatories, which is a telescope that uses a turntable. The results show that this model can significantly reduce the residual systematic errors due to nonlinearity in the azimuth axis compared with the linear model. 相似文献
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随着频率使用率的提高, 射电天文台址地面或空间存在强电磁干扰致使望远镜接收机系统处于非线性状态. 为减少强电磁干扰的影响、提高天文观测效率, 提出了一种基于望远镜远场区域的强干扰源规避方法. 首先, 通过仿真分析确定的射电望远镜远场方向图, 结合望远镜与干扰源之间的位置关系, 分析了强电磁干扰到达射电望远镜焦点处的功率响应, 并依据接收机第2阶中频放大器性能参数, 确定射电望远镜处于非饱和状态的规避角度计算方法. 其次, 采用该方法计算分析了民航飞机对射电望远镜的影响, 若民航飞机上有主动发射的干扰源, 且不经过反射等传播现象, 当射电望远镜主波束轴偏开一定方向后, 可有效降低对射电望远镜的干扰强度. 相似文献
4.
《New Astronomy》2016
This paper presents a new model for improving the pointing accuracy of a telescope. The Denavit–Hartenberg (D–H) convention was used to perform an error analysis of the telescope's kinematics. A kinematic model was used to relate pointing errors to mechanical errors and the parameters of the kinematic model were estimated with a statistical model fit using data from two large astronomical telescopes. The model illustrates the geometric errors caused by imprecision in manufacturing and assembly processes and their effects on the pointing accuracy of the telescope. A kinematic model relates pointing error to axis position when certain geometric errors are assumed to be present in a telescope. In the parameter estimation portion, the semi-parametric regression model was introduced to compensate for remaining nonlinear errors. The experimental results indicate that the proposed semi-parametric regression model eliminates both geometric and nonlinear errors, and that the telescope's pointing accuracy significantly improves after this calibration. 相似文献
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I. A. Usenko L. N. Berdnikov V. V. Kravtsov A. Yu. Kniazev R. Chini V. H. Hoffmeister O. Stahl H. Drass 《Astronomy Letters》2011,37(10):718-725
For seven faint southern Cepheids (WW Car, SX Car, UZ Car, UY Car, GX Car, HW Car, YZ Car), we have determined their atmospheric
parameters and chemical composition for the first time based on ten high-resolution (R = 50 000) spectra taken with the 1.5-m Hexapod telescope at the Joint Observatory of the Northern Catholic University (Antofagasta,
Chile) and the Ruhr University (Bochum, Germany). Six objects from the list demonstrate atmospheric parameters and chemical
composition typical of Cepheids that have passed through the first dredge-up phase, while WW Car is probably an anomalous
Cepheid. According to our preliminary estimates, it has an overabundance of CNO, a deficit of sodium and aluminum, and a slight
deficit of magnesium, with iron and other elements being underabundant relative to the Sun. 相似文献
6.
High-resolution spectroscopy of Mercury has been obtained with two different instruments in 2006: the EMMI instrument at the 3.6-m NTT telescope of ESO La Silla Chile and the ESPADON spectrograph at the 3.6-m CFHT telescope on top of Mauna Kea (Hawaii). The disk of the planet has been scanned for spatial variation of the exospheric species. The large spectral range and high resolution allow simultaneous measurements of the integrated column density of Na and K.We measure Na/K ratio between 80 and 400 with values between 60 and 90 when the telescope was pointed towards the subsolar region of Mercury’s disk and much larger value when we looked to other part of the exosphere. Moreover, we observed that the Na and K exospheres display very different spatial distributions. Even if these two species are probably ejected with very similar mechanisms from the surface, their differences in mass and sensitivity to solar pressure acceleration imply very different behavior in Mercury’s exosphere. 相似文献
7.
射电望远镜天线伺服控制系统中的非线性特性, 对系统动力学特性辨识有着显著的影响, 会提高辨识难度, 增加辨识模型的复杂程度. 系统非线性特性的测量与补偿也会增加系统辨识工作量. 针对上述问题, 提出了一种基于非线性采样数据的线性重构方法, 用于动力学特性建模. 通过提取原采样数据的相位与幅值, 对受到噪声与非线性畸变影响的系统采样数据进行线性重构, 降低待辨识模型的复杂度. 搭建了半实物实验平台, 以平台实际采样为基础, 重构线性数据, 利用奇异值法与自回归神经网络评估并辨识平台动力学模型. 实验结果表明, 建模数据奇异值拐点从100阶下降至40阶, 仅用10个神经网络节点200次训练即实现了模型辨识. 相似文献
8.
O. V. Antyufeyev V. M. Shulga I. I. Zinchenko 《Kinematics and Physics of Celestial Bodies》2016,32(6):276-282
The high-mass star-forming region IRAS 17333-3606 has been mapped in the 13CO (J = 2–1) and C18O (J = 2–1) lines in the submillimeter wavelength range using the APEX (Chile) radio telescope. The analysis of the low-velocity part of the molecular outflow has been carried out, and the main parameters of the outflow have been determined. We have used a novel approach for calculating parameters of the low-velocity part of bipolar molecular outflows in molecular clouds. The approach excludes the influence of the surrounding cloud on the parameters of the outflow. The mass of the low-velocity part is much greater than that of the high-velocity part of the molecular outflow, while their energies are comparable. The core of the young stellar object is significantly deformed by the impact of the bipolar outflow. 相似文献
9.
C.-I. Lagerkvist G. Hahn M. Lundstrm J. S. V. Lagerros O. Hernius G. Tancredi 《Astronomische Nachrichten》1997,318(2):135-139
More than 7000 positions of moving objects have been detected on 33 films obtained with the Schmidt telescope at the European Southern Observatory in Chile during August and September 1995. The majority of these asteroids are previously unobserved. This paper presents the astrometric methods as well as the magnitude determinations. The derived positions for the numbered asteroids are presented and for these improved orbital elements have been calculated using all available positions. 相似文献
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C.-I. Lagerkvist G. Hahn M. Lundstrm J. S. V. Lagerros O. Hernius G. Tancredi 《Astronomische Nachrichten》1997,318(3):183-186
More than 7 000 positions of moving objects were detected on 33 films obtained with the Schmidt telescope at the European Southern Observatory in Chile during August and September 1995. The majority of these asteroids are previously unobserved. This paper presents the results for 62 unnumbered asteroids with provisional designations found in the fields. References to the derived positions for these asteroids are given and improved orbital elements have been calculated using all available positions. 相似文献
12.
L. Woltjer 《Experimental Astronomy》2009,26(1-3):123-132
In 1964, the European Southern Observatory (ESO) came into being as a response to the need of European astronomers for access to large telescopes in good observing conditions. The original plan called for a 3.6 m telescope in addition to a number of smaller instruments. The 3.6 m telescope took some 12 years to build, while ESO headquarters moved from Hamburg to CERN to Garching near Munich, and during the times of office of three Directors General, and it was built on La Silla in Chile, where superior sites had been found. After 1982, when Italy and Switzerland joined the original six member countries, ESO was able to expand by building the 3.5 m New Technology Telescope, and ultimately planning and constructing the VLT on Paranal. At present ESO is a stable organization that has been successful in its original aims, and in view of new plans can look forward in confidence. 相似文献
13.
光污染和光学天文台址保护 总被引：1，自引：0，他引：1
讨论了天光背景对光学天文台的背景，综述了造成光污染的主要途径，介绍了防止光污染的几个主要国际组织和国际上对天文台址的保护立法，提出了减少污染的主要措施。为国内进行光学天文台址保护采取措施以至（国家的或者地方的）立法提供参考。 相似文献
14.
C. R. Kitchin 《Astrophysics and Space Science》1976,45(1):119-124
The envelope model and emission region radius of six Be stars have been determined from 36 lines on 15 spectra taken with the Isaac Newton telescope. The results have been compared with earlier determinations to search for changes with the time. No definite evidence for such changes has been found, although there may be an indication of a change in Per. A re-determination of the errors involved in the method of analysis shows that these are smaller than previously estimated and range from about 9% to 35% for both envelope model and emission region radius. 相似文献
15.
G. Hildebrandt 《Astronomische Nachrichten》1993,314(4):289-295
The five stars HD 11112, HD 170747, HD 186651, HD 205390 and HD 224834 are a second group of objects enclosed in a larger observational programme for the search of rapid oscillations. They have been observed with the 50 cm photoelectrical ESO telescope at La Silla (Chile). For the star HD 205390 a variation of 163.8 min was found. The two objects HD 11112 and HD 186651 are suspected to be variable with periods of 139 min and 142.2 min and its overtones, respectively. But a verification of these results is necessary. For the last two objects HD 170747 and HD 224834 no variations were detected. 相似文献
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S. V. Pilipenko M. V. Tkachev A. A. Ermash T. I. Larchenkova E. V. Mikheeva V. N. Lukash 《Astronomy Letters》2017,43(10):644-655
The extragalactic background radiation produced by distant galaxies emitting in the far infrared limits the sensitivity of telescopes operating in this range due to confusion. We have constructed a model of the infrared background based on numerical simulations of the large-scale structure of the Universe and the evolution of dark matter halos. The predictions of this model agree well with the existing data on source counts. We have constructed maps of a sky field with an area of 1 deg2 directly from our simulated observations and measured the confusion limit. At wavelengths 100–300 μm the confusion limit for a 10-m telescope has been shown to be at least an order of magnitude lower than that for a 3.5-m one. A spectral analysis of the simulated infrared background maps clearly reveals the large-scale structure of the Universe. The two-dimensional power spectrum of these maps has turned out to be close to that measured by space observatories in the infrared. However, the fluctuations in the number of intensity peaks observed in the simulated field show no clear correlation with superclusters of galaxies; the large-scale structure has virtually no effect on the confusion limit. 相似文献
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The European Near Earth Asteroid Research (EURONEAR) is a project which envisions to build a coordinated network which will follow-up and recover potentially hazardous asteroids (PHAs) and near earth asteroids (NEAs). We aim to include in EURONEAR two automated 1 m telescopes located in Chile and Europe, in addition to other non-permanent facilities. Astrometry will be the main aim of the project in order to secure and follow-up newly discovered NEAs, also to recover PHAs at their second or following oppositions, while photometry of bright PHAs will bring information on their physical properties. In this paper, first we review briefly the existent and past NEAs programs. Next, we include the results obtained in 2006 from three observing runs at Pic du Midi using the 1 m telescope, Haute-Provence employing the 1.2 m telescope, and Bucharest using a small 23 cm telescope. These add a total of 153 positions for 16 PHAs and NEAs, which were accepted by Minor Planet Center. Recently, a 1 m telescope was allocated by ESO in La Silla to be automated and used as the Southern dedicated facility by EURONEAR. 相似文献