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| 1 | Two freedom linear parameter varying μ synthesis control for flight environment testbed显示文摘To solve the problem of robust servo performance of Flight Environment Testbed(FET)of Altitude Ground Test Facilities(AGTF) over the whole operational envelope, a two-degree-offreedom μ synthesis method based on Linear Parameter Varying(LPV) schematic is proposed, and meanwhile a new structure frame of μ synthesis control on two degrees of freedom with double integral and weighting functions is presented, which constitutes a core support part of the paper. Aimed at the problem of reference command's rapid change, one freedom feed forward is adopted, while another freedom output feedback is used to meet good servo tracking as well as disturbance and noise rejection; furthermore, to overcome the overshoot problem and acquire dynamic tuning,the integral is introduced in inner loop, and another integral controller is used in outer loop in order to guarantee steady errors; additionally, two performance weighting functions are designed to achieve robust specialty and control energy limit considering the uncertainties in system. As the schedule parameters change over large flight envelope, the stability of closed-loop LPV system is proved using Lyapunov inequalities. The simulation results show that the relative tracking errors of temperature and pressure are less than 0.5% with LPV μ synthesis controller. Meanwhile, compared with non-LPV μ synthesis controller in large uncertainty range, the proposed approach in this research can ensure robust servo performance of FET over the whole operational envelope. | Meiyin ZHU Xi WANG Zhihong DAN Song ZHANG Xitong PEI | 2019 | Chinese Journal of Aeronautics2019，32，5： | 5 |
| 2 | A review of modeling,simulation,and control technologies of altitude ground test facilities for control application显示文摘As the pivotal test equipment of aero-engines design,finalization,improvement,modification,etc.,the Altitude Ground Test Facilities(AGTF)plays an important role in the research and development of the aero-engines.With the rapid development of advanced high-performance aeroengine,the increasing demand of high-altitude simulation test is driving AGTF to improve its test ability and level of automation and intelligence.The modeling method,simulation tool,and control technology are the key factors to support the improvement of the AGTF control system.The main purpose of this paper is to provide an overview of modeling methods,simulation tools,and control technologies in AGTF control system for future research.First,it reviews the evolution of AGTF in the world,from the early formative stage to integration stage.Then,the mathematical modeling method of AGTF for control application is overviewed.Furthermore,the simulation tools used in the AGTF control system are overviewed from numerical simulation to hardware-in-loop simulation and further to semi-physical simulation.Meanwhile,the control technologies used in the AGTF control system are summarized from single-variable control to multivariable integrated control,and from classical control theory to modern control theory.Finally,recommendations for future research are outlined.Therefore,this review article provides extensive literature information for the modeling,simulation,and control design of AGTF for control application. | Xitong PEI Xi WANG Jiashuai LIU Meiyin ZHU Zhihong DAN Ai HE Keqiang MIAO Louyue ZHANG Zheng XU | 2023 | Chinese Journal of Aeronautics2023，36，9： | 0 |
| 3 | Quantum-dot light-emitting diodes with Fermi-level pinning at the hole-injection/hole-transporting interfaces显示文摘Quantum-dot light-emitting diodes(QLEDs)are multilayer electroluminescent devices promising for next-generation display and solid-state-lighting technologies.In the state-of-the-art QLEDs,hole-injection layers(HILs)with high work functions are generally used to achieve efficient hole injection.In these devices,Fermi-level pinning,a phenomenon often observed in heterojunctions involving organic semiconductors,can take place in the hole-injection/hole-transporting interfaces.However,an in-depth understanding of the impacts of Fermi-level pinning at the hole-injection/hole-transporting interfaces on the operation and performance of QLEDs is still lacking.Here,we develop a set of NiOx HILs with controlled work functions of 5.2–5.9 eV to investigate QLEDs with Fermi-level pinning at the hole-injection/hole-transporting interfaces.The results show that despite that Fermi-level pinning induces identical apparent hole-injection barriers,the red QLEDs using HILs with higher work functions show improved efficiency roll-off and better operational stability.Remarkably,the devices using the NiOx HILs with a work function of 5.9 eV demonstrate a peak external quantum efficiency of~18.0%and a long T95 operational lifetime of 8,800 h at 1,000 cd·m^(−2),representing the best-performing QLEDs with inorganic HILs.Our work provides a key design principle for future developments of the hole-injection/hole-transporting interfaces of QLEDs. | Maopeng Xu Desui Chen Jian Lin Xiuyuan Lu Yunzhou Deng Siyu He Xitong Zhu Wangxiao Jin Yizheng Jin | 2022 | Nano Research2022，15，8： | 0 |
| 4 | Flexible Diodes/Transistors Based on Tunable p-n-Type Semiconductivity in Graphene/Mn-Co-Ni-O Nanocomposites显示文摘We report a novel Mn-Co-Ni-O(MCN)nanocomposite in which the p-type semiconductivity of Mn-Co-Ni-O can be manipulated by addition of graphene.With an increase of graphene content,the semiconductivity of the nanocomposite can be tuned from p-type through electrically neutral to n-type.The very low effective mass of electrons in graphene facilitates electron tunneling into the MCN,neutralizing holes in the MCN nanoparticles.XPS analysis shows that the multivalent manganese ions in the MCN nanoparticles are chemically reduced by the graphene electrons to lower-valent states.Unlike traditional semiconductor devices,electrons are excited from the filled graphite band into the empty band at the Dirac points from where they move freely in the graphene and tunnel into the MCN.The new composite film demonstrates inherent flexibility,high mobility,short carrier lifetime,and high carrier concentration.This work is useful not only in manufacturing flexible transistors,FETs,and thermosensitive and thermoelectric devices with unique properties but also in providing a new method for future development of 2D-based semiconductors. | Lihong Su Zhou Yang Xitong Wang Ziao Zou Bo Wang Gary Hodes Ninghui Chang Yongyong Suo Zhibo Ma Haoxu Wang Yucheng Liu Junping Zhang Shuanhu Wang Yuefei Li Fengxia Yang Jixin Zhu Fei Gao Wei Huang Shengzhong Liu | 2022 | Research2022，，1： | 0 |
| 5 | Modified robust optimal adaptive control for flight environment simulation system with heat transfer uncertainty显示文摘To solve the rapid transient control problem of Flight Environment Simulation System(FESS) of Altitude Ground Test Facilities(AGTF) with large heat transfer uncertainty and disturbance, a new adaptive control structure of modified robust optimal adaptive control is presented.The mathematic modeling of FESS is given and the influence of heat transfer is analyzed through energy view. To consider the influence of heat transfer in controller design, we introduce a matched uncertainty that represents heat transfer influence in the linearized system of FESS. Based on this linear system, we deduce the design of modified robust optimal adaptive control law in a general way. Meanwhile, the robust stability of the modified robust optimal adaptive control law is proved through using Lyapunov stability theory. Then, a typical aero-engine test condition with Mach Dash and Zoom-Climb is used to verify the effectiveness of the devised adaptive controller. The simulation results show that the designed controller has servo tracking and disturbance rejection performance under heat transfer uncertainty and disturbance;the relative steady-state and dynamic errors of pressure and temperature are both smaller than 1% and 0.2% respectively. Furthermore,the influence of the modification parameter c is analyzed through simulation. Finally, comparing with the standard ideal model reference adaptive controller, the modified robust optimal adaptive controller obviously provides better control performance than the ideal model reference adaptive controller does. | Meiyin ZHU Xi WANG Xitong PEI Song ZHANG Zhihong DAN Nannan GU Shubo YANG Keqiang MIAO Huairong CHEN Jiashuai LIU | 2021 | Chinese Journal of Aeronautics2021，34，2： | 0 |
| 6 | μ-Synthesis control with reference model for aeropropulsion system test facility under dynamic coupling and uncertainty显示文摘Due to the dynamic coupling and multi-source uncertainties,it is difficult to accurately control the pressure and temperature of the Aeropropulsion System Test Facility(ASTF)in the presence of rapid command and large disturbance.This paper presents the design ofμ-synthesis control to solve the problem.By incorporating the pressure ratio into the linear equation of the control valve,the modeling error of ASTF in the low frequency range is effectively reduced.Then,an uncertain model is established by considering various factors,including parameter variations,modeling error in the low frequency range,unmodeled dynamics,and changes in the working point.To address the dynamic coupling,a diagonal reference model with desired performance is incorporated intoμ-synthesis.Furthermore,all weighting functions are designed according to the performance requirements.Finally,theμ-controller is obtained by using the standardμ-synthesis method.Simulation results indicate that theμ-controller decouples the pressure and temperature dynamics of ASTF.Compared with the multivariable PI controller,integral-μcontroller,and double integral-μcontroller,the proposedμ-controller can achieve higher transient accuracy and better disturbance rejection.Moreover,the robustness of theμ-controller is demonstrated by Monte Carlo simulations. | Jiashuai LIU Xi WANG Xi LIU Meiyin ZHU Xitong PEI Song ZHANG Zhihong DAN | 2023 | Chinese Journal of Aeronautics2023，36，10： | 0 |
| 7 | Gas-assisted magnetic separation for the purification of proteins in batch systems显示文摘 | Zhini Liu Liangrong Yang Tingting Dong Wensong Li Xitong Sun Menghao Zhu Zhengkang Duan Qingfen Liu Huizhou Liu | 2016 | Particuology2016，14，1： | 0 |
| 8 | Flexible Diodes/Transistors Based on Tunable p-n-Type Semiconductivity in Graphene/Mn-Co-Ni-O Nanocomposites显示文摘We report a novel Mn-Co-Ni-O(MCN)nanocomposite in which the p-type semiconductivity of Mn-Co-Ni-O can be manipulated by addition of graphene.With an increase of graphene content,the semiconductivity of the nanocomposite can be tuned from p-type through electrically neutral to n-type.The very low effective mass of electrons in graphene facilitates electron tunneling into the MCN,neutralizing holes in the MCN nanoparticles.XPS analysis shows that the multivalent manganese ions in the MCN nanoparticles are chemically reduced by the graphene electrons to lower-valent states.Unlike traditional semiconductor devices,electrons are excited from the filled graphite band into the empty band at the Dirac points from where they move freely in the graphene and tunnel into the MCN.The new composite film demonstrates inherent flexibility,high mobility,short carrier lifetime,and high carrier concentration.This work is useful not only in manufacturing flexible transistors,FETs,and thermosensitive and thermoelectric devices with unique properties but also in providing a new method for future development of 2D-based semiconductors. | Lihong Su Zhou Yang Xitong Wang Ziao Zou Bo Wang Gary Hodes Ninghui Chang Yongyong Suo Zhibo Ma Haoxu Wang Yucheng Liu Junping Zhang Shuanhu Wang Yuefei Li Fengxia Yang Jixin Zhu Fei Gao Wei Huang Shengzhong Liu | 2021 | Research2021，，1： | 0 |
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