检索结果-南通市图书馆

Calculating real-time surface deformation for large active surface radio antennas using a graph neural network

在线全文

学校读者我要写书评

暂无评论

Astronomical Techniques and Instruments 2024年第5期1卷 267-274页

作者： Zihan Zhang Qian Ye Li Fu qinghui liu Guoxiang Meng School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China

This paper presents an innovative surrogate modeling method using a graph neural network to compensate for gravitational and thermal deformation in large radio ***,rapid compensation is feasible for gravitational deformation but not for temperature-induced *** introduction of this method facilitates real-time calculation of deformation caused both by gravity and *** the surrogate model involves two key ***,the gravitational and thermal loads are encoded,which facilitates more efficient learning for the neural *** is followed by employing a graph neural network as an end-to-end *** model effectively maps external loads to deformation while preserving the spatial correlations between *** results affirm that the proposed method can successfully estimate the surface deformation of the main reflector in real-time and can deliver results that are practically indistinguishable from those obtained using finite element *** also compare the proposed surrogate model method with the out-of-focus holography method and yield similar results.

关键词： Large radio telescope Surface deformation Surrogate model Graph neural network

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

在线全文

学校读者我要写书评

暂无评论

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

The Tianma 65 m radio telescope antenna

在线全文

学校读者我要写书评

暂无评论

Astronomical Techniques and Instruments 2024年第5期1卷 247-259页

作者： Biao Du Yuanpeng Zheng Guoxi liu Yifan Zhang Wancai Zhang Lijun Zhang Shunyou Qin Zhiqiang Shen qinghui liu Bin Li Jinqing Wang 54th Research Institute of China Electronics Technology Group Corporation Shijiazhuang 050081China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China

The Tianma 65 m radio telescope(TMRT)at Shanghai is a fully steerable single-dish radio telescope in China,operating at centimeter to millimeter wavelengths(1.25 GHz to 50 GHz).This paper presents details on the main specifications,design,performance analysis,testing,and construction of the telescope *** measured total efficiency is better than 50%over the whole elevation angle range,first sidelobe levels are less than−20 dB,antenna system noise temperatures are less than 70 K at 30°elevation angle,and pointing accuracy is less than 3″.The measured and calculated results are in good agreement,verifying the effectiveness of the design and analysis.

关键词： Radio telescope Reflector antenna High sensitivity Homology design High pointing accuracy

Surface shape detection methods for large radio telescopes

在线全文

学校读者我要写书评

暂无评论

Astronomical Techniques and Instruments 2024年第5期1卷 275-283页

作者： Zhengxiong Sun Jinqing Wang Linfeng Yu Yongchen Jiang Zheng Lou Yongbin Jiang Rongbin Zhao Qian Ye qinghui liu Guangli Wang Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China Key Laboratory of Radio Astronomy Chinese Academy of SciencesNanjing 210023China Shanghai Key Laboratory of Space Navigation and Positioning Techniques Shanghai 200030China University of Chinese Academy of Sciences Beijing 100049China Purple Mountain Observatory Chinese Academy of SciencesNanjing 210023China

The surface accuracy of a radio telescope is directly related to its operational efficiency and detection *** is crucial under high-frequency observation conditions,where surface shape errors need to be controlled to within 1/16 of the working *** addition,the primary reflector of large radio telescopes is subject to dynamic deformation,caused by factors such as gravity and thermal *** paper presents a method for detecting the surface shape of radio telescopes using radio interferometry techniques combined with active reflector adjustment *** enables accurate assessment and correction of surface errors,ensuring the electrical performance of the radio *** study investigates the practical applications of high-precision measurement techniques,such as microwave holography,out-of-focus holography,and wavefront distortion methods at the Tianma 65 m radio telescope(TMRT).Furthermore,the study presents the construction method of gravity models at different elevation angles and demonstrates the efficacy of the active reflector *** results of the measurements indicate that the application of these methods to the TMRT has led to a notable enhancement of the accuracy of the primary reflector and a substantial improvement in efficiency in the *** a process of iterative measurements and adjustments,the surface shape error is ultimately reduced to 0.28 mm root mean square(RMS).

关键词： Radio telescope Holographic measurements Surface shape measurements Antenna efficiency

The Tianma 65 m radio telescope at Shanghai

在线全文

学校读者我要写书评

暂无评论

Astronomical Techniques and Instruments 2024年第5期1卷 239-246页

作者： qinghui liu Zhiqiang Shen Xiaoyu Hong Qian Ye Bin Li Jinqing Wang Rongbing Zhao Li Fu Weiye Zhong Lingling Wang Juan Li Zhen Yan Wu Jiang Bo Xia Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China

The Shanghai Tianma 65 m radio telescope(TMRT)is a large,fully rotatable radio telescope with multiple scientific *** main body of the telescope and four low-frequency receiving systems,including L,C,and S/X bands,were completed between 2008 and *** 2013 to 2017,four high-frequency receiving systems,including Ku,K,Ka,and Q bands,were constructed and their performance was comprehensively *** are three main innovations.(1)A fully movable large radio telescope system with advanced performance and complete functions has been built.(2)An advanced,reliable main reflector adjustment system has been completed,overcoming gravity deformation and creating a large antenna with a main reflective surface accuracy of 0.28 mm(root mean square)for any elevation.(3)Five innovative technologies have been developed to achieve high-precision pointing in any direction within 3″.The TMRT has made a crucial contribution to the orbital measurement and positioning of China’s lunar and deep space *** enhancing China's ability to participate in international VLBI observations and radio astronomy,this has facilitated a series of achievements in observational radio astronomical research,in areas such as VLBI,spectral lines,and pulsars.

关键词： Radio telescope Tianma Large antenna Receiving system Surface accuracy

考虑粗糙度的FRP-混凝土单剪试验细观模拟

在线全文

学校读者我要写书评

暂无评论

力学季刊 2024年第1期45卷 58-69页

作者：陈珍平刘庆辉张雷乔丕忠河海大学力学与材料学院江苏南京211100 黄河水利委员会黄河水利科学研究院河南郑州450003 河南省水电工程磨蚀测试与防护工程技术研究中心河南郑州450003 上海交通大学船舶海洋与建筑工程学院上海200240

将混凝土模拟为由砂浆和骨料构成的二相复合材料,考虑混凝土表面的粗糙度,建立纤维增强树脂(Fiber Reinforced Polymer, FRP)-混凝土单剪试验细观有限元模型.为描述FRP-混凝土单剪试验过程中的损伤失效过程,分别采用塑性损伤模型和线弹... 详细信息

将混凝土模拟为由砂浆和骨料构成的二相复合材料,考虑混凝土表面的粗糙度,建立纤维增强树脂(Fiber Reinforced Polymer, FRP)-混凝土单剪试验细观有限元模型.为描述FRP-混凝土单剪试验过程中的损伤失效过程,分别采用塑性损伤模型和线弹性模型模拟混凝土两相材料和FRP的力学行为.为揭示混凝土表面粗糙度对FRP-混凝土单剪试验的影响,生成均方根高度分别为0.4 mm和0.8 mm的二维随机粗糙表面.研究结果表明,建立的FRP-混凝土细观有限元模型能够有效模拟FRP-混凝土单剪试验中的损伤失效过程,得到的荷载位移曲线和破坏模式均与试验结果有良好的一致性;随着混凝土表面粗糙度的增加,环氧树脂与混凝土上表面机械咬合力增加,FRP-混凝土试样承载力也随之提升.

关键词： FRP-混凝土单剪试验细观模拟随机骨料模型二维随机粗糙表面

在线全文

学校读者我要写书评

暂无评论

复合碱对电子电路行业废水处理的影响

印制电路信息 2024年第1期32卷 42-46页

作者：许东辉刘庆辉南通深南电路有限公司江苏南通226302

电子电路行业在生产过程中会产生废水,需要进行处理。在废水的处理过程中,需要大量使用碱类药剂来调节pH值。为降低碱类药剂成本,业内广泛使用复合碱替代液碱来处理废水。研究了含钙成分的碱类应用于废水处理后,对废水系统运行成本、废... 详细信息

电子电路行业在生产过程中会产生废水,需要进行处理。在废水的处理过程中,需要大量使用碱类药剂来调节pH值。为降低碱类药剂成本,业内广泛使用复合碱替代液碱来处理废水。研究了含钙成分的碱类应用于废水处理后,对废水系统运行成本、废水处理效果、废水污泥产量及设备设施结垢的影响。分析表明,使用复合碱处理废水有助于节约成本、稳定废水处理效果,但需结合现场设备实际使用情况合理使用。

关键词：电子电路行业复合碱废水污泥量结垢影响废水处理效果

三黄通泻合剂治疗脂源性胰腺炎30例临床观察

在线全文

学校读者我要写书评

暂无评论

湖南中医杂志 2024年第3期40卷 5-8页

作者：刘卿辉游运舸喻长红刘姣湖南中医药大学附属常德医院湖南常德415000 常德市第一中医医院湖南常德415000

目的:观察三黄通泻合剂灌肠治疗脂源性胰腺炎(HLP)的临床疗效。方法:将60例HLP患者随机分为治疗组和对照组,每组各30例。对照组予以西医常规治疗,治疗组在对照组的基础上加用三黄通泻合剂灌肠治疗。比较2组腹痛缓解时间、首次排便时间,... 详细信息

目的:观察三黄通泻合剂灌肠治疗脂源性胰腺炎(HLP)的临床疗效。方法:将60例HLP患者随机分为治疗组和对照组,每组各30例。对照组予以西医常规治疗,治疗组在对照组的基础上加用三黄通泻合剂灌肠治疗。比较2组腹痛缓解时间、首次排便时间,治疗前后的C反应蛋白(CRP)、三酰甘油(TG)水平及平均住院时间。结果:治疗组腹痛缓解时间、首次排便时间、平均住院时间均较对照组短(P<0.05),且2组CRP、TG水平治疗前后组内比较及治疗后组间比较,差异均有统计学意义(P<0.05)。结论:三黄通泻合剂可以快速缓解患者腹痛及便秘等症状,显著抑制炎症反应,快速降低TG水平,缩短住院时间,总体疗效显著,值得临床推广。

关键词：脂源性胰腺炎三黄通泻合剂灌肠

在线全文

学校读者我要写书评

暂无评论

婺源茶树群体种的适制性研究及品质评价

食品研究与开发 2024年第2期45卷 51-57页

作者：梅黎青徐雨琴刘庆辉滕杰刘洋江西农业大学农学院江西南昌330045 江西省本无尘茶业有限责任公司江西上饶333200

以婺源茶树群体种为研究对象,参照当地茶叶制作工艺制得婺源名优绿茶(婺源仙枝、婺源茗眉、婺源特供)、婺源红茶和婺源白茶5种成品茶,并对其进行主要生化品质分析、挥发物检测和感官审评。结果表明,5种茶的水浸出物、茶多酚、可溶性糖... 详细信息

以婺源茶树群体种为研究对象,参照当地茶叶制作工艺制得婺源名优绿茶(婺源仙枝、婺源茗眉、婺源特供)、婺源红茶和婺源白茶5种成品茶,并对其进行主要生化品质分析、挥发物检测和感官审评。结果表明,5种茶的水浸出物、茶多酚、可溶性糖、游离氨基酸、没食子酸和咖啡碱的含量均符合该类茶的品质特点,同时表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)和儿茶素(catechin,C)的含量较高。感官审评和挥发性组分分析发现,婺源仙枝含有较高比例的顺-己酸-3-己烯酯和β-芳樟醇并表现出“栗香”的香气特点,婺源茗眉及婺源特供则含有较高含量的香叶醇、β-芳樟醇、吲哚、水杨酸甲酯并呈现出“清香”的香气特点。

关键词：婺源茶树群体种适制性生化成分香气感官审评