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Approach and landing guidance design for reusable launch vehicle using multiple sliding surfaces technique

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Chinese Journal of Aeronautics 2017年第4期30卷 1582-1591页

作者： xiangdong liu Fengdi ZHANG Zhen LI Yao ZHAO School of Automation Beijing Institute of Technology Beijing 100081 China National Key Laboratory of Complex System Intelligent Control and Decision Beijing Institute of Technology Beijing100081 China China Academy of Launch Vehicle Technology Beijing 100076 China

An autonomous approach and landing（A＆L） guidance law is presented in this paper for landing an unpowered reusable launch vehicle（RLV） at the designated runway touchdown. Considering the full nonlinear point-mass dynamics, a guidance scheme is developed in threedimensional space. In order to guarantee a successful A＆L movement, the multiple sliding surfaces guidance（MSSG） technique is applied to derive the closed-loop guidance law, which stems from higher order sliding mode control theory and has advantage in the finite time reaching *** global stability of the proposed guidance approach is proved by the Lyapunov-based *** designed guidance law can generate new trajectories on-line without any specific requirement on off-line analysis except for the information on the boundary conditions of the A＆L phase and instantaneous states of the RLV. Therefore, the designed guidance law is flexible enough to target different touchdown points on the runway and is capable of dealing with large initial condition errors resulted from the previous flight phase. Finally, simulation results show the effectiveness of the proposed guidance law in different scenarios.

关键词： Finite time control Landing guidance Lyapunov stability Reusable launch vehicle Sliding mode control

Phase Structure and Electrochemical Properties of Rare Earth Based Hydrogen Storage Alloys

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Journal of Rare Earths 2004年第Z1期22卷 228-231页

作者： Chen Weidong liu xiangdong liu Xiao Che Guangdong School of Material Science and Technology Inner Mongolia University of Technology Huhhot 010062 China School of Material Science and Technology Inner Mongolia University of Technology Huhhot 010062 China School of Material Science and Technology Inner Mongolia University of Technology Huhhot 010062 China School of Material Science and Technology Inner Mongolia University of Technology Huhhot 010062 China

The rare earth based hydrogen storage alloys MmxM1 1 - x ( Ni3.55 Co0.75 Mn0.4 A10.3 ) ( x = 0 ～ 0.5 ) were investigated in this *** Ml: Mm ratio to change the content of La,Ce,Pr and Nd in the alloys and then to change the phase structure, the influences of phase structure on the electrochemical properties were *** results indicate that the main phase of all alloys is LaNi5 with CaCu5 type structure and the crystal lattices constants of LaNi5 are changed with increasing x value, i.e, decreased a-axis, increased c-axis and axis ratio and nonlinear decreased crystal *** crystal volume of the alloy with x = 0.3 is larger than *** is second phase A1LaNi4 in alloys when x≥0.3, which decrease the discharge capacity, but increase the cycling stability and high rate discharge *** comprehensively, the alloy with x = 0.3 shows the higher discharge capacity and the better cycling stability.

关键词： rare earth based hydrogen storage alloy phase structure activation discharge capacity cycling stability high rate discharge ability

Observer-based finite-time sliding mode control for reentry vehicle

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International Journal of Intelligent Computing and Cybernetics 2015年第4期8卷 345-362页

作者： xiangdong liu Xiaohuan Ren Yongzhi Sheng School of Automation Beijing Institute of TechnologyKey Laboratory of Complex System Intelligent Control and DecisionMinistry of EducationBeijingPeople’s Republic of China

Purpose–The purpose of this paper is to design a disturbance observer-based finite-time global sliding mode control scheme for the attitude tracking control problem of the reentry vehicle with parameter uncertainties and ***/methodology/approach–Feedback linearization is first introduced to transform vehicle model into three independent second order uncertain *** a finite-time controller(FTC)is proposed for the nominal system on the basis of the homogeneity *** the integral sliding mode method is introduced for the vehicle with *** finite time convergence is achieved and global robustness is also assured by the combination of finite time control method and integral sliding mode ***,to improve the attitude angle tracking accuracy a novel finite time disturbance observer(DO)is ***–Simulation is made for the reentry vehicle with disturbances *** the results show the finite-time convergence,tracking accuracy and robustness of the proposed ***/value–The proposed control strategy has three *** of all it can achieve finite time convergence and avoid ***,it can also realize global ***,a new kind of DO is introduced to improve the tracking accuracy.

关键词： Nonlinear control Robust control Variable structure control

High-throughput microfluidic production of carbon capture microcapsules:fundamentals,applications,and perspectives

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International Journal of Extreme Manufacturing 2024年第3期6卷 330-361页

作者： xiangdong liu Wei Gao Yue Lu Liangyu Wu Yongping Chen College of Electrical Energy and Power EngineeringYangzhou UniversityYangzhouJiangsu 225127People’s Republic of China Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjingJiangsu 210096People’s Republic of China Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application School of Environmental Science and EngineeringSuzhou University of Science and TechnologySuzhouJiangsu 215009People’s Republic of China

In the last three decades,carbon dioxide(CO_(2)) emissions have shown a significant increase from various *** address this pressing issue,the importance of reducing CO_(2) emissions has grown,leading to increased attention toward carbon capture,utilization,and storage *** these strategies,monodisperse microcapsules,produced by using droplet microfluidics,have emerged as promising tools for carbon capture,offering a potential solution to mitigate CO_(2) ***,the limited yield of microcapsules due to the inherent low flow rate in droplet microfluidics remains a *** this comprehensive review,the high-throughput production of carbon capture microcapsules using droplet microfluidics is focused ***,the detailed insights into microfluidic chip fabrication technologies,the microfluidic generation of emulsion droplets,along with the associated hydrodynamic considerations,and the generation of carbon capture microcapsules through droplet microfluidics are *** review highlights the substantial potential of droplet microfluidics as a promising technique for large-scale carbon capture microcapsule production,which could play a significant role in achieving carbon neutralization and emission reduction goals.

关键词： carbon capture microcapsules droplet microfluidic high-throughput production carbon neutralization

Second-order time-varying sliding mode control for reentry vehicle

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International Journal of Intelligent Computing and Cybernetics 2013年第3期6卷 272-295页

作者： Jie Geng Yongzhi Sheng xiangdong liu Key Laboratory of Complex System Intelligent Control and Decision School of AutomationBeijing Institute of TechnologyMinistry of EducationBeijingPeople’s Republic of China

Purpose-The purpose of this paper is to design a global robust and continuous control scheme for the attitude tracking control problem of the reentry vehicle with parameter uncertainties and ***/methodology/approach-First,feedback linearization is applied to the model of reentry vehicle,resulting in three independent uncertain *** a new second-order time-varying sliding function is proposed,based on which a continuous second-order time-varying sliding mode control(SOTVSMC)law is proposed for each *** global robustness and convergence performance of the closed-loop reentry vehicle control system under the proposed control law are ***-Simulation is made for a reentry vehicle through the assumption that there is external disturbance to aerodynamic moment and the aerodynamic parameters as well as the atmospheric density are *** results verify the validity and robustness of the proposed ***/value-The SOTVSMC attitude controller based on feedback linearization is proposed for the reentry *** advantages of the proposed SOTVSMC are ***,the global second order sliding mode is established,which implies that the closed-loop system is global robust against matched parameter uncertainties and disturbances in ***,the chattering problem is significantly alleviated.

关键词： Flight control Nonlinear control Real-time systems Robust control Variable structure control

Near minimum-time feedback attitude control with multiple saturation constraints for agile satellites

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Chinese Journal of Aeronautics 2016年第3期29卷 722-737页

作者： liu xiangdong Xin Xing Li Zhen Chen Zhen Sheng Yongzhi School of Automation Beijing Institute of Technology National Key Laboratory of Complex System Intelligent Control and Decision Beijing Institute of Technology

Agile satellites are of importance in modern aerospace applications, but high mobility of the satellites may cause them vulnerable to saturation during attitude maneuvers due to limited rating of actuators, This paper proposes a near minimum-time feedback control law for the agile satellite attitude control system. The feedback controller is formed by specially designed cascaded sub-units. The rapid dynamic response of the modified Bang Bang control logic achieves the near optimal property and ensures the non-saturation properties on three-axis. To improve the dynamic performance, a model reference control strategy is proposed, in which the oniline near optimal attitude maneuver path is generated by the cascade controller and is then tracked by a nonlinear back-stepping controller. Furthermore, the accuracy and the robustness of the control system are achieved by momentum-based on-line inertial identification. The rapid attitude maneuvering can be applied for tasks including the move to move case. Numerical simulations are conducted to verify the effectiveness of the proposed control strategy in terms of the saturation-free property and rapidness.

关键词： Actuator saturation Attitude control Identification Momentum transfer Satellites

Insight into Urban Faults by Wavelet Multi-Scale Analysis and Modeling of Gravity Data in Shenzhen,China

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Journal of Earth Science 2018年第6期29卷 1340-1348页

作者： Chuang Xu Haihong Wang Zhicai Luo Hualiang liu xiangdong liu MOE Key Laboratory of Fundamental Physical Quantities Measurement School of PhysicsHuazhong University of Science and Technology School of Geodesy and Geomatics Wuhan University Key Laboratory of Geospace Environment and Geodesy Ministry of EducationWuhan University China Water Resources Beifang Investigation Design and Research Co.Ltd.

Urban faults in Shenzhen are potential threats to city security and sustainable development. In consideration of the importance of the Shenzhen fault zone, the author provide a detailed interpretation on gravity data model. Bouguer gravity covering the whole Shenzhen City was calculated with a 1-km resolution. Wavelet multi-scale analysis（MSA） was applied to the Bouguer gravity data to obtain the multilayer residual anomalies corresponding to different depths. In addition, 2D gravity models were constructed along three profiles. The Bouguer gravity anomaly shows an NE-striking high-low-high pattern from northwest to southeast, strongly related to the main faults. According to the results of MSA, the correlation between gravity anomaly and faults is particularly significant from 4 to 12 km depth. The residual gravity with small amplitude in each layer indicates weak tectonic activity in the crust. In the upper layers, positive anomalies along most of faults reveal the upwelling of high-density materials during the past tectonic movements. The multilayer residual anomalies also yield important information about the faults, such as the vertical extension and the dip direction. The maximum depth of the faults is about 20 km. In general, NE-striking faults extend deeper than NW-striking faults and have a larger dip angle.

关键词： urban faults Bouguer gravity anomaly wavelet multi-scale analysis gravity modeling Shenzhen

Range Distribution Parameters of Implanted ^(19)F Ions in Ni_(0.8)Fe_(0.2) Alloy

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Chinese Physics Letters 1995年第5期12卷 285-288页

作者： TAN Chunyu XIA Yueyuan liu xiangdong liu Jitian WANG Fengxiang Department of Physics Shandong UniversityJinan 250100

Depth profiles of fluorine in ^(19)F^(+) implanted Ni_(0.8)Fe_(0.2) alloy have been accurately measured by using ^(19)F(p,αγ)^(16)O resonance nuclear reaction at ER=872.1keV.A proper convolution calculation method was used to extract the true distribution of fluorine from the experimental excitation yield *** range parameters,R,and ΔR_(p),were thereby obtained and compared with those simulated wit TRIM'90 *** shows that the experimental R_(p) values agree with the Monte Carlo simulation values very well,while the experimental ΔR_(p) values are systematically larger than the calculation values.

关键词： alloy fluorine thereby

Noise Trader Model of Agricultural Product Prices： Evidence from the Chinese Garlic Market

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Frontiers of Business Research in China 2014年第3期8卷 327-345页

作者： Jingtao Yi xiangdong liu School of Business Renmin University of China Beijing 100872 China

This paper explores the determinants of the abnormal and volatile fluctuations of China＇s agricultural product prices in recent years by examining the trading behavior of traders, especially that of irrational noise traders. We present an overlapping generations model of the garlic market in which noise traders with erroneous beliefs influence prices. Noise traders＇ beliefs create a risk in the price of agricultural products that deters rational arbitrageurs from aggressively betting against them through changing supplies in a way that enables prices to diverge significantly from fundamental values even in the absence of fundamental risk. We also show that asymmetry of supply information, low price elasticity of demand, speculative capital inflows, restricted distribution channels, distorted wholesale markets from the perspective of market mechanisms and low risk aversion, biased self-attribution, and projection bias from the perspective of investor psychology, all influence expectations of investors and increase the volatility of agricultural product prices.

关键词： noise trader agricultural product price volatility distributionsystem