基于线性数据重构的天线动力学模型辨识方法          下载免费PDF全文

侯晓拯  许谦  李琳  易乐天  薛飞  王惠  许多祥  何飞龙 《天文学报》2022,63(5):58

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   

青藏铁路多年冻土地区碎石护坡路基非线性分析   总被引：1，自引：0，他引：1  

田亚护  刘建坤  张鲁新 《工程地质学报》2006,14(4):470-475

为了研究碎石护坡对冻土区路基温度场的影响,以青藏铁路试验段现场观测的气候和地质资料为上边界条件,运用带相变瞬态温度场有限元数值解法,对不同厚度的碎石护坡路基进行了分析。结果表明:粒径为10 cm的碎石护坡对多年冻土区路基的稳定性有保护作用;碎石护坡对路基坡脚附近地温影响较大,采用碎石护坡对防止路基纵向裂缝的产生有一定的作用;实际应用中碎石层厚度不能太厚。  相似文献   

Scheduling for Robonet‐1 homogenous telescope network     

S. N. Fraser 《Astronomische Nachrichten》2006,327(8):779-782

The Robonet‐1 homogenous telescope network consists of 3 fully robotic 2 m class telescopes. I describe how the observation requests submitted by external users and automated user agents are selected for observation by the individual telescope schedulers. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Pointing and tracking analysis of alt‐azimuthal multi‐focus telescopes: the THEMIS case     

G. Mainella  C. Briand  L. Marchal  C. Le Men 《Astronomische Nachrichten》2003,324(4):309-312

We discuss the pointing and tracking configuration of THEMIS which may be considered as representative of those alt‐azimuthal telescopes with an optical configuration with multiple focal planes, not all locked to both the alt‐azimuthal coordinates. In the THEMIS case two focal planes are present. The primary focus F1 is locked to the alt‐azimuthal mount, while the secondary focus F2 (which is used by the instruments), is only locked to the azimuth angle. The different contributions to the final accuracy of both absolute pointing and tracking as observed at F2 are defined, and an extimation of the contribution of each component of the whole chain which affects the field position at F2 (software, mechanical and optical) is given. The experimental data are the result of a test campaign carried on at THEMIS in February and March 2002. We can say that (a) for all the used observing configurations, the tracking accuracy is coherent at any point along the trajectory with the correspondent absolute pointing accuracy, which is an indication for the quality of the telescope dynamical performances (b) the main contribution to the residual field shift which is observed at F2 arises from the opto‐mechanical alignment configuration of the optics between F1 and F2, which therefore is the crucial point for such multi‐focus configuration. More informations can be found at the official THEMIS website (http://www.themis.iac.es).  相似文献   

斜向波与带填料开孔板式防波堤相互作用的研究          下载免费PDF全文

刘洪杰  刘勇  李玉成 《海洋学报》2009,31(4):159-166

基于线性势流理论,对斜向波与消浪室内带部分填料的开孔板式防波堤结构的相互作用进行了理论研究.利用匹配特征函数展开法给出了开孔防波堤结构反射系数和波浪力系数的理论计算方法,在极限情况下的计算结果与已有结果一致.利用数值算例分析了开孔结构反射系数和波浪力系数的主要影响因素.增加消浪室内填料厚度通常可以降低开孔墙结构的波浪力系数,加大结构的反射系数.随着波浪入射角度的增加,带填料防波堤结构的反射系数值先减小,达到最小值后又单调增加.  相似文献   

顾及轮廓信息和DRLSE模型的遥感影像瞬时水边线快速提取          下载免费PDF全文

杨志海  王广军  高智雄  冯磊  梁四海 《海洋科学》2023,47(4):79-88

针对利用传统瞬时水边线提取方法处理高分辨率遥感影像存在提取结果不连续、效率不高和无法同时提取多片水域等问题, 提出了一种顾及轮廓信息和距离正则化水平集演化(distance regularized level set evolution, DRLSE)模型的遥感影像瞬时水边线快速提取方法, 并将其应用于福建泉州附近海域瞬时水边线提取。首先,使用DRLSE模型提取地物轮廓信息, 以解决经典阈值方法水边线提取结果不连续问题; 其次, 利用DRLSE模型的初始矩形轮廓中心位置和周长信息, 对噪声点等轮廓进行自动剔除, 并提取多片水域, 以提高瞬时水边线提取后处理效率。研究结果表明:相较于泛洪算法、Canny算子和CV(Chan-Vese)模型, 应用本方法进行大陆海岸线瞬时水边线提取更高效, 且提取结果连续、精度更高。  相似文献   

The NST: First results and some lessons for ATST and EST     

P.R. Goode  R. Coulter  N. Gorceix  V. Yurchyshyn  W. Cao 《Astronomische Nachrichten》2010,331(6):620-623

In January 2009, first light observations with the NST (New Solar Telescope) in Big Bear Solar Observatory (BBSO) were made. NST has a 1.7 m primary with a 1.6 m clear aperture. First observational results in TiO and Hα are shown and discussed. The NST primary mirror is the most aspheric telescope mirror deployed to date. The NST is early in its commissioning, and the plans for this phase will be sketched. Lessons learned in building and implementing the NST are germane for the ATST and EST telescopes and will be discussed. The NST has an off‐axis Gregorian configuration consisting of a parabolic primary, heat‐stop, elliptical secondary and diagonal flats. The focal ratio of the primary mirror is f/2.4. The working wavelength range covers from 0.4 to 1.7 µm in the Coudé Lab beneath the telescope and all wavelengths including the far infrared at the Nasmyth focus on the dome floor (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献