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Numerical analysis of modal tomography for solar multi-conjugate adaptive optics

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Research in Astronomy and Astrophysics 2012年第4期12卷 465-471页

作者： Bing Dong De-qing ren Xi Zhang Physics ＆ Astronomy Department California State University Northridge CA 91330-8268 USA National Astronomical Observatories/Nanjing Institute of Astronomical Optics ＆ Technology Chinese Academy of Sciences Nanjing 210042 China

Multi-conjugate adaptive optics （MCAO） can considerably extend the cor- rected field of view with respect to classical adaptive optics, which will benefit solar observation in many aspects. In solar MCAO, the Sun structure is utilized to provide multiple guide stars and a modal tomography approach is adopted to implement three- dimensional wavefront restorations. The principle of modal tomography is briefly re- viewed and a numerical simulation model is built with three equivalent turbulent lay- ers and a different number of guide stars. Our simulation results show that at least six guide stars are required for an accurate wavefront reconstruction in the case of three layers, and only three guide stars are needed in the two layer case. Finally, eigen- mode analysis results are given to reveal the singular modes that cannot be precisely retrieved in the tomography process.

关键词： instrumentation: multi-conjugate adaptive optics -- tomography

Risk analysis for a cascade reservoir system using the brittle risk entropy method

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Science China(Technological Sciences) 2016年第6期59卷 882-887页

作者： YANG Yin ren qing Wen TIAN Ying XIONG Yao College of Hydraulic Conservation and Hydropower Engineering Hohai University Department of Engineering Mechanics Hohai University

The principal means of conserving water and utilizing hydropower in China is to exploit the use of a series of reservoirs in a cascade. This method and its inherent engineering safety problems are receiving increasing attention nowadays. In the field of engineering safety analysis, much work has focused on single reservoir projects in the past few years, but there is little research available on the safety risk analysis of cascade reservoirs, either within China or internationally. Therefore, a framework for risk analysis on the cascade reservoir system based on the theory of system engineering is constructed in this article. A cascading failure model is established and the connection degree factor discussed. In addition, the importance degree of the subsystem, which can be calculated by combining the analytical hierarchy process and the entropy weight method, is explained. According to brittleness theory of a complex system, brittle risk entropy is proposed as a performance index for measuring the collapse uncertainty of the cascade reservoir system. In addition, the brittle risk of the cascade reservoir system is predicted, which provides a reference for safety analysis in water conservation and hydropower construction projects in China.

关键词： cascading failure model safety analysis risk assessment complex system brittle risk entropy

A low-cost and high-performance technique for adaptive optics static wavefront correction

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Research in Astronomy and Astrophysics 2021年第7期21卷 261-268页

作者： De-qing ren Tian-Yu Zhang Gang Wang California State University Northridge Department of Physics and AstronomyNorthridgeCA 91330USA National Astronomical Observatories/Nanjing Institute of Astronomical Optics and Technology Chinese Academy of SciencesNanjing 210042China CAS Key Laboratory of Astronomical Optics and Technology Nanjing Institute of Astronomical Optics and TechnologyNanjing 210042China University of Chinese Academy of Sciences Beijing 100049China

Non-Common Path Error(NCPE) is one of the factors that limit an Adaptive Optics(AO)system from delivering ultra-high performance. To correct the NCPE associated static aberration, we propose a simple but robust and high-performance pupil-plane based wavefront measurement and correction technique, which can copy a single-mode fiber generated perfect wavefront to the AO system via an iteration optimization process, and the NCPE can be effectively corrected by directly commanding the Deformable Mirror(DM) of the AO system. Compared with the previous focal-plane based approach that uses focal plane based Point Spread Function(PSF) for correction evaluation, the pupil-plane based approach can be reliably and rapidly converged to a global optimization result and provides better performance, in particular for an AO system with a large initial static wavefront error. This technique we proposed can be implemented in astronomical AO systems where extremely high performance is required.

关键词： astronomical instrumentation:adaptive optics astronomical instrumentation:high angular resolution astronomical techniques:high angular resolution

Integral precession calibration method of PIGA on linear vibration table

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Chinese Journal of Aeronautics 2024年第3期37卷 219-236页

作者： Chuang SUN Shun-qing ren Jun-wei CAO Ru HUO Department of Automation Tsinghua UniversityBeijing 100084China School of Astronautics Harbin Institute of TechnologyHarbin 150001China Beijing National Research Center for Information Science and Technology Tsinghua UniversityBeijing 100084China Faculty of Information technology Beijing University of TechnologyBeijing 100124China

Linear vibration table can provide harmonic accelerations to excite the nonlinear error terms of Pendulous Integrating Gyro Accelerometer(PIGA).Integral precession calibration method is proposed to calibrate PIGA on a linear vibration table in this *** on the precise expressions of PIGA’s inputs,the error calibration model of PIGA is *** angular velocity errors of PIGA are suppressed by integer periodic precession and the errors caused by non-integer periods vibrating are *** complete calibration process,including planning,preparation,PIGA testing,and coefficient identification,is designed to optimize the test operations and evaluate the calibration *** effect of the main errors on calibration uncertainty is analyzed and the relative sensitivity function is proposed to further optimize the test *** and simulation results verify that the proposed 10-position calibration method can improve calibration uncertainties after compensating for the related *** order of calibration uncertainties of the second-and third-order coefficients are decreased to 10^(-8)(rad.s^(-1))/g^(2)and 10^(-8)(rad.s^(-1))/g3,*** with the other two classical calibration methods,the calibration uncertainties of PIGA’s nonlinear error coefficients can be effectively reduced and the proportional residual errors are decreased less than 3×10-6(rad.s^(-1))/g by using the proposed calibration method.

关键词： PIGA Linear vibration table Vibration measurement Calibration Error analysis Uncertainty analysis

Working Principle and Error Analysis for Hemispherical Resonator Gyro under Force-rebalance Mode

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Journal of Harbin Institute of Technology(New Series) 2013年第1期20卷 75-80页

作者： Hong-Bo Zhao Shun-qing ren Space Control and Inertial Technology Research Center Harbin Institute of Technology

The two control methods, namely the general-control and the quadrature-control modes for HRG under force-rebalance mode were introduced firstly. Then the azimuth of antinode on the hemispherical resonator was deduced. The dynamics equations of resonator under the nonuniformity of density distribution were established by way of Bubonov-Galerkin method which is commonly used for solution of differential equations, and the state equation was established through the dynamics equations. The analytic solutions of the vibration displacement and the velocity were achieved by solving the state equation, and then the ratio of rebalance excitation to primary excitation was derived under the two working modes, thus the estimation of input angular rate of HRG were obtained. By comparing and calculating these two modes, the error caused by resonator's machining defects can be greatly inhibited under quadrature-control, and the fourth harmonic density error's tolerance were calculated to ensure the accuracy of HRG under these two modes.

关键词： hemispherical resonator gyro force-rebalance mode quadrature-control density distribution nonuniformity

Solar GLAO and TAO:performance comparisons

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Research in Astronomy and Astrophysics 2018年第7期18卷 125-132页

作者： De-qing ren Xi Zhang Si-Zhen Liu Physics&Astronomy Department California State University NorthridgeNorthridgeCalifornia 91330USA National Astronomical Observatories/Nanjing Institute of Astronomical Optics&Technology Chinese Academyof SciencesNanjing 210042China Key Laboratory of Astronomical Optics&Technology Nanjing Institute of Astronomical Optics&TechnologyChinese Academy of SciencesNanjing 210042China University of Chinese Academy of Sciences Beijing 100049China

Multi-conjugate adaptive optics （MCAO）, consisting of several deformable mirrors （DMs）, can significantly increase the adaptive optics （AO） correction field of view. Current MCAO can be realized by either star-oriented or layer-oriented approaches. For solar AO, ground-layer adaptive optics （GLAO） can be viewed as an extreme case of layer-oriented MCAO in which the DM is conjugated to the ground, while solar tomography adaptive optics （TAO） that we proposed recently can be viewed as star-oriented MCAO with only one DM. Solar GLAO and TAO use the same hardware as conventional solar AO, and therefore it will be important to see which method can deliver better performance. In this article, we compare the performance of solar GLAO and TAO by using end-to-end numerical simulation software. Numerical simulations of TAO and GLAO with different numbers of guide stars are conducted. Our results show that TAO and GLAO produce the same performance if the DM is conjugated to the ground, but TAO can only generate better performance when the DM is conjugated to the best height. This result has important application in existing one-DM solar AO systems.

关键词： Adaptive Optics GLAO MCAO

3D Effects on Vortex-Shedding Flow and Hydrodynamic Coefficients of A Vertically Oscillating Cylinder with A Bottom-Attached Disk

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China Ocean Engineering 2017年第4期31卷 428-437页

作者： WANG Quan KOU Yu-feng ZHU ren-qing CHEN Hong State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration Shanghai 200240China School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhengjiang 212002China Shanghai Waigaoqiao Shipbuilding CO. LTD.Shanghai 200240China

Vortex-shedding flow induced by the vertical oscillation of a cylinder with bottom-attached disks of different diameter ratio Dd/Dc and thickness ratio td/Dc is studied by a 3D （three-dimensional） numerical model developed in this paper, and compared with the results obtained through 2D （two-dimensional） numerical model. The high-order upwind scheme is applied to stabilize the computation, and convergence is accelerated by the multi-grid method. Qualitative and quantitative analyses of the differences between the 2D and 3D simulation results reveal the 3D effect on the flow field characteristics and hydrodynamic coefficients of the vertically oscillating cylinder with a bottom-attached disk. The 3D effect on the fluid field is mainly reflected in the significance of three vortex-shedding patterns： ωx has a greater effect on the flow fields around the sharp edges relative to the vortices generated in the 2D simulation. In the slice along the axial orientation, the vortex effect of ωy along the radial axis is smaller than that of ωx along the circumferential direction, indicating the radial effect on the velocity more pronounced than the circumferential effect around the sharp edges of the disk. The rotational interaction ωz of the fluid in the horizontal plane during the heave motion is insignificant. Based on the 2D and 3D simulation results, the turning points that separate the increasing regimes of the added mass coefficient and damping ratio are identified. The dependence of the turning point on the diameter ratio Dd/Dc and thickness ratio td/Dc are discussed in detail.

关键词： 3D effect vortex-shedding pattern added mass coefficient damping ratio vertical oscillation

Separation and determination of pyrrolidinium ionic liquid cations by ion chromatography with direct conductivity detection

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Chinese Chemical Letters 2013年第6期24卷 503-505页

作者： ren qing Zhang Hong Yu Xiao Jiao Sun Key Laboratory of Photonic and Electronic Bandgap Materials Ministry of Education and College of Chemistry and Chemical EngineeringHarbin Normal University

A method for rapid and simultaneous determination of multiple pyrrolidinium ionic liquid cations by ion chromatography with direct conductivity detection was *** separations were performed on a cation exchange column using ethylenediamine-acetonitrile as the mobile *** effects of chromatographic column and the mobile phase,as well as the column temperature on the retention of the cations were *** retention rules of the cations under different chromatographic conditions were *** retention of the cations followed the carbon number *** method has been successfully applied to the determination of three ionic liquids synthesized by a chemical laboratory.

关键词： Ionic liquids Pyrrolidinium cations Ion chromatography Conductivity detection Retention rules

High-contrast coronagraph for ground-based imaging of Jupiter-like planets

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Research in Astronomy and Astrophysics 2010年第2期10卷 189-198页

作者： Jiang-Pei Dou De-qing ren Yong-Tian Zhu National Astronomical Observatories / Nanjing Institute of Astronomical Optics ＆ Technology Chinese Academy of Sciences Nanjing 210042 China Key Laboratory of Astronomical Optics ＆ Technology Nanjing Institute of Astronomical Optics ＆ Technology Chinese Academy of Sciences Nanjing 210042 China Physics ＆ Astronomy Department California State University Northridge 18111 Nordhoff Street Northridge California 91330-8268

We propose a high-contrast coronagraph for direct imaging of young Jupiter-like planets orbiting nearby bright stars. The coronagraph employs a step- transmission filter in which the intensity is apodized with a finite number of steps with identical transmission in each step. It should be installed on a large ground-based telescope equipped with a state-of-the-art adaptive optics system. In this case, contrast ratios around 10-6 should be accessible within 0.1 arcsec of the central star. In recent progress, a coronagraph with a circular apodizing filter has been developed, which can be used for a ground-based telescope with a central obstruction and spider structure. It is shown that ground-based direct imaging of Jupiter-like planets is promising with current technology.

关键词： instrumentation: high angular resolution- methods: laboratory numer- ical -- techniques: coronagraphy apodization -- planetary systems