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Observer-based multi-objective parametric design for spacecraft with super flexible netted antennas

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Science China(Information Sciences) 2020年第7期63卷 161-181页

作者： Guang-Ren DUAN tian-yi ZHAO Center for Control Theory and Guidance Technology Harbin Institute of Technology

A multi-objective parametric design method that based on the robust observer is proposed for the attitude control of satellites with super flexible netted antennas. First, a parametric observer-based controller is obtained based on the eigen-structure assignment theory. The closed-loop poles are assigned to desired positions or regions, and full degrees of freedom of the design, which are characterized by a set of parameters, are preserved under the proposed control law. Second, the obtained parameters are comprehensively optimized to make the closed-loop system have lower eigenvalue sensitivity, a smaller control gain, and stronger tolerance to high-order unmodeled dynamics and external disturbances. Finally, comparative simulations are carried out based on practical engineering parameters of a satellite in order to verify the effect of the proposed method, and also to show their superiority over the traditional proportional-integral-derivative(PID) controller with filters and the traditional dynamic compensators.

关键词： parametric design of control systems multi-objective designs robust observers super flexible spacecraft parameter perturbations high-order flexible modes

Chaos in Compact Binaries with Frequency Map Analysis

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Chinese Journal of Astronomy and Astrophysics 2006年第6期6卷 705-715页

作者： yi Xie tian-yi Huang Department of Astronomy Nanjing University Nanjing 210093

The dynamics of compact binaries is very complicated because of spin-orbit cou- pling and spin-spin coupling. With Laskar＇s frequency map analysis （FMA） and frequency diffusion as an indicator, we found that misalignment of the spins and orbital angular momentum has a great effect on the dynamics, and for systems with different mass ratios β = m2/ml chaos occurs at different spin-orbit configurations. For equal-mass binaries （β = 1）, chaos occurs when the spins nearly cancel each other out. For some other systems （for exampleβ - 1/2）, the binaries are irregular, even chaotic, when the spins are perpendicular to the orbital angular momentum. For the case where gravitational radiation is taken into account, we give an analytic estimation for the frequency diffusion based on the decay of the orbit, which is roughly consistent with our simulations. This means the FMA is not suitable as a chaos indicator for weak chaotic cases with dissipative terms.

关键词： celestial mechanics - (stars:) binaries (including multiple) close

On Subsonic and Subsonic-Sonic Flows with General Conservatives Force in Exterior Domains

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Acta Mathematicae Applicatae Sinica 2023年第1期39卷 3-16页

作者： Xumin GU tian-yi WANG Department of Mathematics Shanghai University of Finance and EconomicsShanghai 200433China Department of Mathematics School of ScienceWuhan University of TechnologyWuhan 430070China The Institute of Mathematical Sciences the Chinese University of Hong KongShatinN.T.Hong Kong Gran Sasso Science Institute viale Francesco Crispi767100 L'AquilaItaly

In this paper, we study the irrotational subsonic and subsonic-sonic fows with general conservative forces in the exterior domains. The conservative forces indicate the new Bernoulli law naturally. For the subsonic case, we introduce a modified cut-off system depending on the conservative forces which needs the varied Bers skill, and construct the solution by the new variational formula. Moreover, comparing with previous results, our result extends the pressure-density relation to the general case. Afterwards we obtain the subsonic-sonic limit solution by taking the extract subsonic solutions as the approximate sequences.

关键词： steady fow homentropic irrotation subsonic fow subsonic-sonic limit

Maximum Likelihood Estimator of the Parameter for a Continuous One-Parameter Exponential Family Under the Optimal Ranked Set Sampling

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Journal of Systems Science & Complexity 2017年第6期30卷 1350-1363页

作者： CHEN Wangxue tian yi XIE Minyu Department of Mathematics and Statistics Jishou University Department of Mathematics and Statistics Central China Normal University

This paper studies a maximum likelihood estimator(MLE) of the parameter for a continuous one-parameter exponential family under ranked set sampling(RSS). The authors first find the optimal RSS according to the character of the family, viz, arrange the RSS based on quasi complete and sufficient statistic of independent and identically distributed(iid) samples. Then under this RSS, some sufficient conditions for the existence and uniqueness of the MLE, which are easily used in practice,are obtained. Using these conditions, the existence and uniqueness of the MLEs of the parameters for some usual distributions in this family are proved. Numerical simulations for these distributions fully support the result from the above two step optimizations of the sampling and the estimation method.

关键词： Complete sufficient statistic continuous one-parameter exponential family maximum likelihood estimator ranked set sampling

Determination of Magnolol and Honokiol by Non-aqueous Capillary Electrophoresis

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Chemical Research in Chinese Universities 2006年第3期22卷 335-338页

作者： tian yi-ling CHEN Guan-hua College of Life Science Agricultural University of Hebei Baoding 071001 P. R. China College of Food Science ＆ Technology Agricultural University of Hebei Baoding 071001 P. R. China

Two active principles in traditional Chinese medicine Magnolia officinalis, magnolol and honokiol, were successfully separated by means of nonaqueous capillary electrophoresis. The effect of the composition of a nonaqueous buffer on column efficiency and resolution, and the effect of acid additives on peak shapes were researched. The separation was conducted with a running buffer in a mixture of methanol/aeetonitrile/formamide （ volume ratio ： 1 ： 2 ： 2 ）, in which the concentrations of Tris, acetic acid, and water were 60 retool/L, 0. 04 mmol/L and 5% （ volume fration）, respectively, and the pH^＊（apperent pH） of the running buffer was 8.96. Magnolol and honokiol were separated on baseline within 20 min. The relative standard deviation of the analytes＇ concentrations in the sample is 1.32% for magnolol and 1.60% for honokiol, and the recoveries of the spiked sample are 98.4% for magnolol and 98. 0% for honokiol, respectively.

关键词： Nonaqueous capillary electrophoresis Magnolol Honokiol

Painlevé analysis, auto-Bäcklund transformations, bilinear forms and soliton solutions for a(2+1)-dimensional variable-coefficient modified dispersive water-wave system in fluid mechanics

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Communications in Theoretical Physics 2023年第2期75卷 46-55页

作者： Fei-Yan Liu yi-tian Gao Ministry-of-Education Key Laboratory of Fluid Mechanics and National Laboratory for Computational Fluid Dynamics Beijing University of Aeronautics and AstronauticsBeijing 100191China

In this paper,we investigate a(2+1)-dimensional variable-coefficient modified dispersive waterwave system in fluid *** prove the Painlevéintegrability for that system via the Painlevé*** find some auto-B?cklund transformations for that system via the truncated Painlevé*** forms and N-soliton solutions are constructed,where N is a positive *** discuss the inelastic interactions,elastic interactions and soliton resonances for the two *** also graphically demonstrate that the velocities of the solitons are affected by the variable coefficient of that system.

关键词： fluid mechanics variable-coefficient modified dispersive water-wave system Painlevéanalysis bilinear forms soliton solutions auto-Bäcklund transformations

Ore Geology,H-O-C Isotopes and 40Ar-39Ar Dating of the Wutonggou Iron Deposit,Eastern tianshan,NW China:Implications for the Source,Timing,and Genesis of Hydrothermal Mineralization in a Sedimentary Iron Deposit

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Journal of Earth Science 2024年第4期35卷 1170-1185页

作者： Chun-Long Wang yi-tian Wang State Key Laboratory of Geological Processes and Mineral Resources Collaborative Innovation Center for Exploration of Strategic Mineral ResourcesSchool of Earth ResourcesChina University of GeosciencesWuhan430074China MNR Key Laboratory of Metallogeny and Mineral Assessment Institute of Mineral ResourcesChinese Academy of Geological SciencesBeijing100037China

The Wutonggou iron deposit is located in the well-known iron metallogenic belt in the eastern tianshan,NW China,and has been regarded as a sedimentary iron *** hydrothermal overprinting could play indispensable roles in the formation of high-grade iron ores in sedimentary iron deposits,previous studies mainly focused on sedimentary-related iron mineralization,while the nature and contribution of hydrothermal fluids are poorly ***,an integrated study of ore geology,H-O-C isotopes and^(40)Ar-^(39)Ar dating,is conducted on the Wutonggou deposit,in order to reveal the features,source,and timing of hydrothermal *** studied deposit includes two mining sections namely the Jianshan and ***δ^(18)O values of early magnetite from the Jianshan section range from+3.0‰to+5.8‰that nearly consistent with classic magmatic magnetite,while increase to 6.3‰-8.0‰in the late *** from the two sections shows comparable H-O isotopic compositions and identical fractionation trends,and is plotted in or periphery to the primary magmatic water *** from the two sections are broadly similar in carbon and oxygen isotopic compositions,and siderite from the Wutonggou section is plotted in the same ***,comparable stable isotopic compositions and evolution trends indicate similar magmatic fluids contributed hydrothermal iron mineralization in the two mining ***,water-rock interactions of varying degrees generated distinct mineralization styles in the Jianshan and Wutonggou sections,and caused the isotopic fractionation in late *** extracted from a hydrothermal siderite ore yielded a^(40)Ar-^(39)Ar plateau age of 299.5±2.0 Ma,indicates the timing of hydrothermal iron mineralization is corresponding to the emplacement of vicinity *** together,the hydrothermal mineralization in the Wutonggou iron deposit was the product of remobilization and upgrading of early sedimentary iron ores,a

关键词： iron deposits H-O-C isotopes 40Ar-39Ar dating sedimentary iron deposits Wutonggou iron deposit eastern tianshan

An Alternative Algorithm for the Symmetry Classification of Ordinary Differential Equations

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Sound & Vibration 2022年第1期56卷 65-76页

作者： yi tian Jing Pang College of Data Science and Application Inner Mongolia University of TechnologyHohhot010080China Inner Mongolia Autonomous Region Engineering and Technology Research Center of Big Data Based Software Service Hohhot010080China College of Science Inner Mongolia University of TechnologyHohhot010051China Inner Mongolia Key Laboratory of Statistical Analysis Theory for Life Data and Neural Network Modeling Inner Mongolia University of TechnologyHohhot010051China

This is the first paper on symmetry classification for ordinary differential equations(ODEs)based on Wu’s *** carry out symmetry classification of two ODEs,named the generalizations of the Kummer-Schwarz equations which involving arbitrary ***,Lie algorithm is used to give the determining equations of symmetry for the given equations,which involving arbitrary ***,differential form Wu’s method is used to decompose determining equations into a union of a series of zero sets of differential characteristic sets,which are easy to be solved *** branch of the decomposition yields a class of symmetries and associated *** algorithm makes the classification become direct and *** Dimitrov Bozhkov,and Pammela Ramos da Conceição have used the Lie algorithm to give the symmetry classifications of the equations talked in this paper in *** this paper,we can find that the differential form Wu’s method for symmetry classification of ODEs with arbitrary function(parameter)is effective,and is an alternative method.

关键词： Kummer-Schwarz equation ordinary differential equations(ODEs) differential form Wu’s method

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

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Acta Metallurgica Sinica(English Letters) 2019年第6期32卷 755-763页

作者： tian-yi Sun Yan-Jun Guo yi-Ming Jiang Jin Li Department of Materials Science Fudan University

The effect of short-time aging in the temperature range between 400 and 1000°C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS)2002 was investigated through the potentiostatic critical pitting temperature(CPT)tests and the Charpy impact *** the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650°C *** CPT of LDSS 2002 specimen aged at 650°C decreased by 28°C,and the impact energy dropped from 69 to 29 J/cm2 compared with the solution-annealed *** electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr2N and M23C6 along the ferrite–austenite grain boundaries.

关键词： Lean duplex stainless steel Aging Pitting corrosion Impact energy Precipitates