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Experimental study on the effect of wind on pointing accuracy of antenna structures

天文技术与仪器(英文) 2024年第05期 284-294页

作者： Li Fu Wang Li Lingling Wang Wen Guo Qinghui Liu Zhiqiang Shen Xu Wang Haiming Liu Shanghai Astronomical Observatory Chinese Academy of Sciences Sichuan Institute of Building Research University of Chinese Academy of Sciences School of Civil Engineering Chongqing Jiaotong University Merchants Chongqing Communications Technology Research & Design Institute Co.Ltd.

Wind loads have instantaneity and turbulence characteristics that will lead to pointing errors in antenna structures, and these errors cannot be ignored in high-frequency observations. Using the Tianma 65 m radio telescope(TMRT) as an example object, the pointing errors caused by wind loads are investigated using an accelerometer system. First, the resonant frequency range of the antenna structure is used for reference to acquire useful signals through the bandpass filtering method. Then, the direct current(DC) component of these signals is filtered out using the fast discrete Fourier transform method, and the baseline of the acceleration is corrected using the least-squares method. Finally, the acceleration integral is solved approximately using the discrete trapezoidal area method, and the structural vibration displacement of the antenna is determined using a double integral of acceleration. The pointing errors are then obtained based on the displacement relationship between the primary and subreflector surfaces. When the wind speed is 3.2 m/s, the antenna pitch angle is 61.7° and the wind direction angle is 80°, the generated pitch pointing error is 3.05'', and the azimuth pointing error is 1.14''. These results are consistent with those obtained via inclinometer measurements, thus validating the signal processing method and the pointing error calculation method proposed in this paper. The research methods and data analysis results reported here provide a basis for further windinduced pointing error correction studies.

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Experimental study on the effect of wind on pointing accuracy of antenna structures

引用

Astronomical Techniques and Instruments 2024年第5期1卷 284-294页

作者： Li Fu Wang Li Lingling Wang Wen Guo Qinghui Liu Zhiqiang Shen Xu Wang Haiming Liu Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China Sichuan Institute of Building Research Chengdu 400074China University of Chinese Academy of Sciences Beijing 101408China School of Civil Engineering Chongqing Jiaotong UniversityChongqing 610000China Merchants Chongqing Communications Technology Research&Design Institute Co.Ltd. Chongqing 400067China

Wind loads have instantaneity and turbulence characteristics that will lead to pointing errors in antenna structures,and these errors cannot be ignored in high-frequency *** the Tianma 65 m radio telescope(TMRT)as an example object,the pointing errors caused by wind loads are investigated using an accelerometer ***,the resonant frequency range of the antenna structure is used for reference to acquire useful signals through the bandpass filtering ***,the direct current(DC)component of these signals is filtered out using the fast discrete Fourier transform method,and the baseline of the acceleration is corrected using the least-squares ***,the acceleration integral is solved approximately using the discrete trapezoidal area method,and the structural vibration displacement of the antenna is determined using a double integral of *** pointing errors are then obtained based on the displacement relationship between the primary and subreflector *** the wind speed is 3.2 m/s,the antenna pitch angle is 61.7°and the wind direction angle is 80°,the generated pitch pointing error is 3.05'',and the azimuth pointing error is 1.14''.These results are consistent with those obtained via inclinometer measurements,thus validating the signal processing method and the pointing error calculation method proposed in this *** research methods and data analysis results reported here provide a basis for further wind-induced pointing error correction studies.

关键词： Accelerometer Double integral Pointing error Bandpass filtering

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ON THE SEPARABLE NONLINEAR LEAST SQUARES PROBLEMS

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Journal of Computational Mathematics 2008年第3期26卷 390-403页

作者： Xin Liu Yaxiang Yuan LSEC ICMSEC Academy of Mathematics and Systems Science Chinese Academy of Sciences and Graduate University of Chinese Academy of Sciences Beijing 100190 China LSEC ICMSEC Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

Separable nonlinear least squares problems are a special class of nonlinear least squares problems, where the objective functions are linear and nonlinear on different parts of variables. Such problems have broad applications in practice. Most existing algorithms for this kind of problems are derived from the variable projection method proposed by Golub and Pereyra, which utilizes the separability under a separate framework. However, the methods based on variable projection strategy would be invalid if there exist some constraints to the variables, as the real problems always do, even if the constraint is simply the ball constraint. We present a new algorithm which is based on a special approximation to the Hessian by noticing the fact that certain terms of the Hessian can be derived from the gradient. Our method maintains all the advantages of variable projection based methods, and moreover it can be combined with trust region methods easily and can be applied to general constrained separable nonlinear problems. Convergence analysis of our method is presented and numerical results are also reported.

关键词： Separable nonlinear least squares problem Variable projection method Gauss-Newton method Levenberg-Marquardt method Trust region method Asymptotical convergence rate Data fitting

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COMPOSITE-STEP LIKE FILTER METHODS FOR EQUALITY CONSTRAINT PROBLEMS

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Journal of Computational Mathematics 2003年第5期21卷 613-624页

作者： Pu-yan Nie(LSEC, ICMSEC, Academy of Mathematics and System Sciences, Chinese Academy of Sciences, Beijing 100080, China) 中科院数学与系统科学院 LSEC ICMSEC CAS 北京 100080

In a composite-step approach, a step Sk is computed as the sum of two components Uk and hk. The normal component Vk, which is called the vertical step, aims to improve the linearized feasibility, while the tangential component hk, which is also called horizontal step, concentrates on reducing a model of the merit functions. As a filter method, it reduces both the infeasibility and the objective function. This is the same property of these two methods. In this paper, one concerns the composite-step like filter approach. That is, a step is tangential component hk if the infeasibility is reduced. Or else, Sk is a composite step composed of normal component Uk, and tangential component hk.

关键词： Composite-step like approaches Filter methods Equality constraints Sequen- tial quadratic programming(SQP) algorithms Normal component Tangential component Convergence.

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A TRUST REGION METHOD FOR SOLVING DISTRIBUTED PARAMETER IDENTIFICATION PROBLEMS

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Journal of Computational Mathematics 2003年第6期21卷 759-772页

作者： Yan-fei Wang Ya-xiang Yuan(LSEC, ICMSEC, Academy of Mathematics and System Sciences, Chinese Academy of Sciences,Beijing 100080, China) LSEC ICMSEC Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100080 China

This paper is concerned with the ill-posed problems of identifying a parameter in an elliptic equation which appears in many applications in science and industry. Its solution is obtained by applying trust region method to a nonlinear least squares error problem. Trust region method has long been a popular method for well-posed problems. This paper indicates that it is also suitable for ill-posed problems. Numerical experiment is given to compare the trust region method with the Tikhonov regularization method. It seems that the trust region method is more promising.

关键词： Parameter identification Ill-posed problems Trust region.

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A Novel Rice Gene, NRR Responds to Macronutrient Deficiency and Regulates Root Growth

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Molecular Plant 2012年第1期5卷 63-72页

作者： Yu-Man Zhang Yong-Sheng Yan Li-Na Wang Kun Yang Na Xiao Yun-Feng Liu Ya-Ping Fu Zong-Xiu Sun Rong-Xiang Fang Xiao-Ying Chen State Key Laboratory of Plant Genomics Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China National Plant Gene Research Center Beijing 100101China Graduate School of the Chinese Academy of Sciences Beijing 100039China Department of Ornamental Horticulture and Landscape Architecture China Agricultural UniversityBeijing 100193China Current address:School of Life Science and Technology University of Electronic Science and Technology of ChinaChengdu 610054China State Key Laboratory of Rice Biology National Rice Research InstituteHangzhou 310006 China

To better understand the response of rice to nutrient stress, we have taken a systematic approach to identify rice genes that respond to deficiency of macronutrients and affect rice growth. We report here the expression and bio- logical functions of a previously uncharacterized rice gene that we have named NRR （nutrition response and root growth）. NRR is alternatively spliced, producing two 5＇-coterminal transcripts, NRRa and NRRb, encoding two proteins of 308 and 223 aa, respectively. Compared to NRRb, NRRa possesses an additional CCT domain at the C-terminus. Expression of NRR in rice seedling roots was significantly influenced by deficiency of macronutrients. Knock-down of expression of NRRa or NRRb by RNA interference resulted in enhanced rice root growth. By contrast, overexpression of NRRa in rice exhibited significantly retarded root growth. These results revealed that both NRRa and NRRb played negative regulatory roles in rice root growth. Our findings suggest that NRRa and NRRb, acting as the key components, modulate the rice root archi- tecture with the availability of macronutrients.

关键词： Nutrient stress alternative splicing root growth rice.

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GIS-based Analysis of Main Air Pollutants of Changchun City in Summer

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Chemical Research in Chinese Universities 2006年第4期22卷 447-450页

作者： JING Nan XIA Bin JING Ti-song Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 P. R. China Graduate School of Chinese Academy of Sciences Beijing 100039 P. R. China College of Environment and Resource Jilin University Changchun 130026 P. R. China

To gain a better understanding of the characteristics of air pollution of Changchun city, P. R. China, in summer, the analytical methods of geographical information system（GIS） and statistical analysis software SPSS were applied to the analysis of the monitored concentrations of SO2 , NO2, and O3 in July of 2002 to 2004 in Changchun city. The results obtained show that the average hourly O3 concentrations in July 2002 and 2004 were higher than the firstlevel hourly standard of China. At the same time, the dynamic distribution of the 03 concentration and the relationship between the concentration of 03 and that of NOx were studied. The air quality evaluation result of Changchun city indicates that the southwest of this city was heavily polluted during the monitored period.

关键词： Air pollutant Dynamic distribution Ozone Summer of Changchun city GIS

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Variations and trends of the freezing and thaw- ing index along the Qinghai-Xizang Railway for 1966-2004

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Journal of Geographical Sciences 2008年第1期18卷 3-16页

作者： JIANG Fengqing HU Ruji LI Zhen Xinjiang Institute of Ecology and Geography CAS Urumqi 830011 China

Annual freezing and thawing index of 7 meteorological stations along the Qing- hai-Xizang Railway were calculated based on daily maximum and minimum temperature records for 1966-2004. Trends of annual freezing and thawing index were analyzed using the Mann-Kendall test and a simple linear regression method. The results show that： 1） The mean annual freezing indices range from 95 to 2300℃·d and the mean annual thawing indices range from 630 to 3250℃·d. The mean annual freezing index of the 7 stations exhibited decreasing trends with decreasing rate of -16.6- -59.1 ℃·d/10a. The mean annual thawing index of these 7 stations showed increasing trends with the related decreasing rate is 19.83-45.6℃·d/10a. 2） The MK trend test indicated the significant decreasing trends （significant at 〈 0.05 significant level） in the annual freezing index for most stations except for Golmud. The significant increasing trends can be observed in the annual thawing index for 4 stations except Golmud and Tuotuohe. Golmud was the only station with no trends in both annual freezing and annual thawing index.

关键词： freezing and thawing index global warming trends Qinghai-Xizang Railway

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Petroleum geological framework and hydrocarbon potential in the Yellow Sea

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Chinese Journal of Oceanology and Limnology 2008年第1期26卷 23-34页

作者：吴时国倪祥龙蔡峰 Key Laboratory of Marine Geology & Environment Institute of Oceanology China Academy of SciencesQingdao 266071 China Graduate School of Chinese Academy of Sciences Beijing 100049 China Institute of Marine Geology China Geological SurveyQingdao 266071 China

Sedimentary basins in the Yellow Sea can be grouped tectonically into the North Yellow Sea Basin (NYSB), the northern basin of the South Yellow Sea (SYSNB) and the southern basin of the South Yellow Sea (SYSSB). The NYSB is connected to Anju Basin to the east. The SYSSB extends to Subei Basin to the west. The acoustic basement of basins in the North Yellow Sea and South Yellow Sea is disparate, having different stratigraphic evolution and oil accumulation features, even though they have been under the same stress regime since the Late Triassic. The acoustic basement of the NYSB features China-Korea Platform crystalline rocks, whereas those in the SYSNB and SYSSB are of the Paleozoic Yangtze Platform sedimentary layers or metamorphic rocks. Since the Late Mesozoic terrestrial strata in the eastern of the NYSB (West Korea Bay Basin) were discovered having industrial hydrocarbon accumulation, the oil potential in the Mesozoic strata in the west depression of the basin could be promising, although the petroleum exploration in the South Yellow Sea has made no break-through yet. New deep reflection data and several drilling wells have indicated the source rock of the Mesozoic in the basins of South Yellow Sea, and the Paleozoic platform marine facies in the SYSSB and Central Rise could be the other hosts of oil or natural gas. The Mesozoic hydrocarbon could be found in the Mesozoic of the foredeep basin in the SYSNB that bears potential hydrocarbon in thick Cretaceous strata, and so does the SYSSB where the same petroleum system exists to that of oil-bearing Subei Basin.

关键词： sedimentary basin petroleum system hydrocarbon potential the Yellow Sea

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A study of time over threshold (TOT) technique for plastic scintillator counter

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Chinese Physics C 2008年第3期32卷 186-190页

作者：吴金杰衡月昆孙志嘉吴冲赵玉达杨桂安姜春华 Institute of High Energy Physics CASBeijing 100049China Graduate University of Chinese Academy of SciencesBeijing 100049China Institute of High Energy Physics CASBeijing 100049China Department of Physics Nanjing UniversityNanjing 210093China

A new charge measurement method, time over threshold （TOT）, has been used in some gas detectors lately. HereTOT is studied for TOF system, made of plastic scintillator counter, which can simplify the electronics of the system. The signal characteristics are measured and analyzed with a high quality oscilloscope, including noise, pedestal, signal amplitude, total charge, rise time and the correlation between them. The TOT and charge are related and can be fitted by some empirical formula. The charge measurement resolution by TOT is given and this will help the design of TOF electronics.

关键词： scintillator counter time over threshold (TOT) charge measurement relative resolution

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