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Relative position determination of a lunar rover using the biased differential phase delay of same-beam VLBI

Science China(Physics,Mechanics & Astronomy) 2011年第12期54卷 2284-2295页

作者： CHEN Ming liu qinghui WU YaJun ZHAO RongBing DAI ZhiQiang Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China Beijing Aerospace Control Center Beijing 100094 China

When only data transmission signals with a bandwidth of 1 MHz exist in the rover, the position can be obtained using the differential group delay data of the same-beam very long baseline interferometry (VLBI). The relative position between a lunar rover and a lander can be determined with an error of several hundreds of meters. When the guidance information of the rover is used to determine relative position, the rover's wheel skid behavior and integral movement may influence the accuracy of the determined position. This paper proposes a new method for accurately determining relative position. The differential group delay and biased differential phase delay are obtained from the same-beam VLBI observation, while the modified biased differential phase delay is obtained using the statistic mean value of the differential group delay and the biased phase delay as basis. The small bias in the modified biased phase delay is estimated together with other parameters when the relative position of the rover is calculated. The effectiveness of the proposed method is confirmed using the same-beam VLBI observation data of SELENE. The radio sources onboard the rover and the lander are designed for same-beam VLBI observations. The results of the simulations of the differential delay of the same-beam VLBI observation between the rover and the lander show that the differential delay is sensitive to relative position. An approach to solving the relative position and a strategy for tracking are also introduced. When the lunar topography data near the rover are used and the observations are scheduled properly, the determined relative position of the rover may be nearly as accurate as that solved using differential phase delay data.

关键词： same-beam VLBI biased differential phase delay relative position determination lunar rover

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Research Progress of Eco-Friendly Portland Cement Porous Concrete:A Review

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Journal of Renewable Materials 2023年第1期11卷 103-130页

作者： Xin Cai Fan Li Xingwen Guo Ren Li Yanan Zhang qinghui liu Minmin Jiang College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing210000China College of Mechanics and Materials Hohai UniversityNanjing210000China Jiangsu Jiuding Green Concrete Corporation Yangzhou225000China China Three Gorges Corporation Beijing100000China

With the great impetus of energy conservation and emission reduction policies in various countries,the proposal of concepts such as“Sponge City”and“Eco-City”,and the emphasis on restoration and governance of ecological environment day by day,portland cement porous concrete(PCPC),as a novel building material,has attracted more and more attention from scientific researchers and *** possesses the peculiar pore structure,which owns numerous functions like river embankment protection,vegetation greening as well as air-cleaning,and has been of wide application in different engineering *** paper reviews the salient properties of PCPC,detailedly expounds the research progress of domestic and foreign literature about this subject in the past ten years(2010–2020),conducts the statistical analysis of the distribution rule of its major properties around the world,combines with the engineering application to summarize the excellent properties of PCPC,and makes a forecast of future research direction.

关键词： Portland cement porous concrete(PCPC) penetrating quality mechanical properties durability photocatalysis endothermic function slope protection with vegetation

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Photo-induced Birefringence of Azo-dye Based on Three-dimensional Opal Photonic Crystals

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Chemical Research in Chinese Universities 2016年第6期32卷 1063-1068页

作者： ZHONG Qiulin ZOU Lu WANG Yinghui SUI Ning liu qinghui ZHANG Liquan ZHANG Hanzhuang Key Laboratory of Physics and Technology for Advanced Batteries Ministry of Education College of Physics Jilin University Changchun 130012 P. R. China

A series of three-dimensional opal photonic crystals based on the polymer was synthesized and applied inthe field of photo-induced birefringence. The data show that the photo-induced birefringence（PIB） of pure Sudan IIIfilm could be enhanced by increasing the thickness of azo films. When Sudan III was distributed on thethree-dimensional opal photonic crystals, the photo-induced birefringence process could be modulated. In addition,the data also exhibit that the PIB processes with different pumping polarization directions are sensitive to the role ofphotonic crystals. The results could be beneficial to further understanding the photo-induced birefringence and uti-lizing the photonic crystals.

关键词： Photonic crystal Photo-reduced birefringence Azo-dye

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SNR periodical variation of Chang'E-3 spacecraft orbiting the Moon

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Chinese Journal of Aeronautics 2016年第2期29卷 470-478页

作者： he qingbao liu qinghui li peijia kawaguchi noriyuki wu yajun zheng xin zhang juan xu zhijun Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China

Chang＇E-3 spacecraft was orbiting the Moon from December 6 14, 2013, and very long baseline interferometry （VLBI） observations were performed to improve the accuracy of its orbit determination. In the process of recording VLBI raw data, 2 bits quantization was implemented. Interesting phenomenon was that signal-to-noise ratio （SNR） of each VLBI station experienced periodical change and had large variation on amplitude while in the Moon＇s orbit, whereas SNR kept in a stable level after Chang＇E-3 landed on the Moon. Influence of varying elevation angle on SNR was analyzed and compensation of 2 bits quantization harmonics to SNR calculation was investigated. Most importantly, telescope system noise temperature increase caused by the Moon was computed along the time of Chang＇E-3 orbiting the Moon, and well matched SNR changing trend in terms of correlation coefficients.

关键词： 2 bits quantization Elevation angle Moon radiation SNR periodical variationVLBI

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THE HAUSDORFF DIMENSION OF THE SPECTRUM OF A CLASS OF GENERALIZED THUE-MORSE HAMILTONIANS

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Acta Mathematica Scientia 2023年第5期43卷 1997-2004页

作者：刘庆晖唐志毅 School of Computer Science and Technology Beijing Institute of TechnologyBeijing 100081China School of Mathematics and Physics Hubei Polytechnic UniversityHuangshi 435003China

Letτbe a generalized Thue-Morse substitution on a two-letter alphabet{a,b}:τ(a)=ambm,τ(b)=bmam for the integer m≥***ξbe a sequence in{a,b}Z that is generated byτ.We study the one-dimensional Schr?dinger operator Hm,λon l2(Z)with a potential given by v(n)=λVξ(n),whereλ>0 is the coupling and Vξ(n)=1(Vξ(n)=-1)ifξ(n)=a(ξ(n)=b).LetΛ2=2,and for m>2,letΛm=m if m≡0 mod 4;letΛm=m-3 if m≡1 mod 4;letΛm=m-2if m≡2 mod 4;letΛm=m-1 if m≡3 mod *** show that the Hausdorff dimension of the spectrumσ(Hm,λ)satisfies that dimHσ(Hm,λ)>logΛm/(log 64m+4).It is interesting to see that dimHσσ(Hm,λ)tends to 1 as m tends to infinity.

关键词： one-dimensional Schrodinger operator generalized Thue-Morse sequence Hausdorff dimension

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A RIGOROUS PROOF ON CIRCULAR WIRELENGTH FOR HYPERCUBES

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Acta Mathematica Scientia 2023年第2期43卷 919-941页

作者：刘庆晖唐志毅 School of Computer Science and Technology Beijing Institute of TechnologyBeijing 100081China

We study embeddings of the n-dimensional hypercube into the circuit with *** prove that the circular wirelength attains a minimum by gray coding;that was called the CT conjecture by Chavez and Trapp(Discrete Applied Mathematics,1998).This problem had claimed to be settled by Ching-Jung Guu in her doctoral dissertation“The circular wirelength problem for hypercubes”(University of California,Riverside,1997).Many argue there are gaps in her *** eliminate the gaps in her dissertation.

关键词： circular wirelength hypercube gray coding

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The time and frequency system of the Tianma 65 m radio telescope

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Astronomical Techniques and Instruments 2024年第5期1卷 260-266页

作者： Lingling Wang qinghui liu Yong Cai Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China University of Chinese Academy of Sciences Beijing 100049

A time and frequency system is a critical component of Very Long Baseline Interferometry(VLBI)stations,providing stable and reliable standards that directly impact data processing *** the Tianma 65 m radio telescope(TMRT),this system has been meticulously designed to ensure long-term reliability and high *** incorporates high-performance hydrogen atomic clocks,high-precision time standards,automatic signal switching,and robust system *** comprehensive approach has enabled the system to achieve long-term reliable operation,successfully supporting both major national engineering tasks and daily scientific *** effectiveness of the system is evidenced by its consistent delivery of the precision and stability required for radio *** article provides an in-depth exploration of the design and operation of the time and frequency system at the Tianma 65 m telescope,examining various aspects of its architecture,implementation,and *** sharing these insights,we aim to contribute knowledge that could benefit similar systems at other VLBI stations,greatly advancing radio astronomy infrastructure.

关键词： Time and frequency system Hydrogen atomic clock Reliability

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Studying the charge carrier properties in CuInS_2 films via femtosecond transient absorption and nanosecond transient photocurrents

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Chinese Physics B 2019年第5期28卷 222-225页

作者： Mingrui Tan qinghui liu Ning Sui Zhihui Kang Liquan Zhang Hanzhuang Zhang Wenquan Wang Qiang Zhou Yinghui Wang Femtosecond Laser Laboratory Key Laboratory of Physics and Technology for Advanced Batteries College of PhysicsJilin University State Key Laboratory of Superhard Materials College of Physics Jilin University

The carrier behavior in CuInS_2 thin films at femtosecond and microsecond time scales is discussed in detail. Transient absorption data suggests that the photo-generated carriers relax rapidly accompanied by a change in energy. The photogenerated charge carriers are extracted by a bias electric field E in the nanosecond transient photocurrent system. An applied E improves the efficiency of photon conversion to charge carriers and enhances the velocity of the extracted charge carriers. In addition, there exists a threshold of illumination intensity in the extraction process of charge carriers in the CuInS_2 thin film, above which carrier recombination occurs. The corresponding loss further increases with illumination intensity and the recombination rate is almost independent of E. Our results provide useful insights into the characteristics of carriers in the CuInS_2 thin film and are important for the operation of optoelectronic devices realized with these films.

关键词： semiconductor film carrier dynamics transient absorption transient photocurrent

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月球背面探测器跟踪的4程多普勒技术

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中国科学：物理学、力学、天文学 2016年第3期46卷 100-107页

作者：刘庆会中国科学院上海天文台上海200030

飞行或着陆于月球背面的探测器,无法从地面直接观测,必须利用更高轨道的探测器中继才能进行跟踪.作为月球背面探测器的一种有效的跟踪手段,本文以SELENE为例,系统性地给出了4程多普勒观测系统的组成、数据处理和应用方法、定轨和重力场... 详细信息

飞行或着陆于月球背面的探测器,无法从地面直接观测,必须利用更高轨道的探测器中继才能进行跟踪.作为月球背面探测器的一种有效的跟踪手段,本文以SELENE为例,系统性地给出了4程多普勒观测系统的组成、数据处理和应用方法、定轨和重力场解算结果,并分析了天线相位特性和自旋对4程多普勒测量精度的影响及改正方法.这些内容对月球背面探测器的跟踪、测控和数传系统的研发和应用提供了参考实例.

关键词：月球背面 4程多普勒着陆器探测器跟踪

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Fibonacci映射的不变闭曲线的存在性

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应用数学学报 2000年第4期23卷 603-609页

作者：刘庆晖武汉大学数学系武汉430072

本文利用Moser扭转定理证明Fibonacci映射在椭圆型二周期点附近存在F^2-不变闭曲线。

关键词：迹映射 Moser扭转定理不变闭曲线 Fibonacci映射存在性

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