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Control techniques of tilt rotor unmanned aerial vehicle systems： A review

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Chinese Journal of Aeronautics 2017年第1期30卷 135-148页

作者： Liu Zhong He Yuqing yang liying Han Jianda State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences Shenyang 110016 China University of Chinese Academy of Sciences Beijing 100049 China

The tilt rotor unmanned aerial vehicle（TRUAV） exhibits special application value due to its unique rotor structure. However, varying dynamics and aerodynamic interference caused by tiltable rotors are great technical challenges and key issues for TRUAV＇s high-powered flight controls, which have attracted the attention of many researchers. This paper outlines the concept of TRUAV and some typical TRUAV platforms while focusing on control techniques. TRUAV structural features, dynamics modeling, and flight control methods are discussed, and major challenges and corresponding developmental tendencies associated with TRUAV flight control are summarized.

关键词： Aircraft structures Dynamics modeling Flight control Tilt rotors Unmanned aerial vehicle(UAV)

Performance comparisons between cellular-only and cellularfWLAN integrated systems based on analytical models

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Frontiers of Computer Science 2013年第4期7卷 486-495页

作者： Guozhi SONG liying yang Jigang WU John SCHORMANS School of Computer Science and Software Tianjin Polytechnic University Tianjin 300387 China School of Electronic Engineering and Computer Science Queen Mary University of London London E14NS UK

To solve the traffic load imbalance issue in cellular networks, which is often in the form of hot-spots caused by the different user mobility levels, one of the good solutions at present is to construct heterogeneous integrated wireless networks that combine cellular networks and wireless local area networks （WLANs） together. In general, the traffic volume is significantly heavier in the hot-spots of cellular networks and a higher data transferring rate can be provided by introducing a WLAN so as to raise the utilization of the channel and achieve a good balance between user satisfaction and the efficiency of the network. In this paper, we provide a comprehensive performance comparison of the systems both before and after the integration, based on an existing mathematical model, focusing on both the qualitative and the quantitative analysis of changes in the performance of the system to validate the efficiency and superiority of the cellular/WLAN integrated systems over cellular-only systems.

关键词： cellular network WLAN heterogeneous wire-less network performance evaluation traffic load balance,horizontal handover vertical handover

Annealing Effect of ZnO on the Performance of Inverted Organic Photovoltaic Devices

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Journal of Materials Science & Technology 2014年第2期30卷 197-202页

作者： Wenjing Qin Guojing Ding Xinrui Xu liying yang Shougen Yin Key Laboratory of Display Materials & Photoelectric Devices(Ministry of Education) and School of Materials Science &Engineering Tianjin University of Technology Tianjin Key Lab for Photoelectric Materials & Devices

ZnO nanoparticles films were prepared via sol-gel process and incorporated into inverted organic photovoltaic devices with a structure of ITO/ZnO/P3HT：PCBM/MoO3/Ag, in which ZnO film served as an electron selective layer. The effects of annealing temperature of ZnO film on the device performance were investigated. When the annealing temperature was 300℃, a well-arranged ZnO thin film was obtained, and the optimized device had doubled short circuit current density （Jsc） and seven-fold higher power conversion efficiency （PCE） compared to the devices without ZnO film. This improvement could be attributed to the enlarged interfacial area of ZnO/active layer and better energy band matching which causes an efficient electron extraction and a decreased interface energy barrier. At particularly high annealing temperature, dramatically increased sheet resistance of indium tin oxide （ITO） was found to cause PCE deterioration. Our finding indicates that it is highly important to investigate both morphology and electrical effects for understanding and optimizing organic photovoltaic （OPV） performance.

关键词： ZnO Inverted organic photovoitaic Annealing effect

Wear Behavior of Cold Pressed and Sintered Al_2O_3/TiC/CaF_2-Al_2O_3/TiC Laminated Ceramic Composite

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Acta Metallurgica Sinica(English Letters) 2013年第2期26卷 157-166页

作者： Xuefeng yang Jian CHENG Peilong SONG Shouren WANG liying yang Yanjun WANG Ken MAO School of Mechanical Engineering University of Jinan Key Laboratory for Anisotropy and Texture of Materials of the Ministry of Education Northeastern University School of Engineering Warwick University

A novel laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite was fabricated through cold pressing and sintering to achieve better anti-wear performance, such as low friction coefficient and low wear rate. Al2O3/TiC/CaF2 and Al2O3/TiC composites were alternatively built layer-by-layer to obtain a sandwich structure. Solid lubricant CaF2 was added evenly into the Al2O3/TiC/CaF2 layer to reduce the friction and wear. Al2O3/TiC ceramic was also cold pressed and sintered for comparison. Friction analysis of the two ceramics was then conducted via a wear-and-tear machine. Worn surface and surface compositions were examined by scanning electron microscopy and energy dispersion spectrum, respectively. Results showed that the laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite has lower friction coefficient and lower wear rate than those of Al2O3/TiC ceramic alone because of the addition of CaF2 into the laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite. Under the friction load, the tiny CaF2 particles were scraped from the Al2O3/TiC/CaF2 layer and spread on friction pairs before falling off into micropits. This process formed a smooth, self-lubricating film, which led to better anti-wear properties. Adhesive wear is the main wear mechanism of Al2O3/TiC/CaF2 layer and abrasive wear is the main wear mechanism of Al2O3/TiC layer.

关键词： Friction and wear characteristics Wear property Ceramic-matrix compos-ites Layer manufacture Surface appearance Sliding

Tribological Properties of Self-lubricating Laminated Ceramic Materials

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Journal of Wuhan University of Technology(Materials Science) 2014年第5期29卷 906-911页

作者：宋培龙杨学锋 WANG Shouren yang liying School of Mechanical Engineering University of Jinan

In order to improve the tribological properties of ceramic composites, Al2O3/TiC-Al2O3/ TiC/CaF2 self-lubricating laminated ceramic composites were prepared by vacuum hot pressing sintering. Experiments were conducted to get mechanical properties and the friction and wear properties were also measured with friction and wear tester. The worn surfaces were observed by scanning electron microscope （SEM） and energy dispersion spectrum （EDS）. The wear resistance properties and the self-lubricating effect of ceramic composites were analyzed. Results show that the Al2O3/TiC-Al2O3/TiC/CaF2 self-lubricating laminated ceramic composites layers are well-defined with a higher bonding strength and the mechanical performances are uniform enough to overcome the anisotropy of weak laminated ceramic composites. In addition, the fracture toughness of Al2O3/TiC layers is also improved. Its friction coefficient and wear rates decrease with the increase of rotation speed and load. Al2O3/TiC-Al2O3/TiC/CaF2 self-lubricating laminated ceramic composites have good wear resistance because of the tribofilm formed by the CaF2 solid lubricants. The wear mechanisms of Al2O3/TiC/ CaF2 layers are abrasive wear and Al2O3/TiC layers are adhesive wear.

关键词： compositcs laminated ceramic materials self-lubricating wear and friction

Active model-based nonlinear system identification of quad tilt-rotor UAV with flight experiments

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Science China(Information Sciences) 2022年第8期65卷 105-119页

作者： Zhong LIU Didier THEILLIOL Yuqing HE Feng GU liying yang Jianda HAN Xi'an Modern Control Technology Research Institute State Key Laboratory of Robotics Shenyang Institute of AutomationChinese Academy of Sciences Institutes for Robotics and Intelligent Manufacturing Chinese Academy of Sciences College of Artificial Intelligence Nankai University Faculte des Sciences et Techniques CRAN UMR 7039CNRSUniversity of Lorraine

To propose an accurate and less complex model of a special unmanned aerial vehicle(UAV),namely tilt-rotor UAV(TRUAV), this study identifies the active model-based nonlinear system of a quadTRUAV. First, a nominal nonlinear model of the vehicle is formulated. Some unstructured nonlinearities are ignored to reduce the complexity of the model. Then, due to the unstable dynamics of the open-loop system,the format of this nominal model is considered to design an innovative smooth-switch attitude control via interconnection and damping assignment passivity-based control(IDA-PBC). Active model-based nonlinear system identification is studied for the vehicle with the designed control method and flight *** model error vector is defined and estimated by the unscented Kalman filter(UKF) to improve the accuracy of the model. The main contribution of this paper is to identify the nominal nonlinear model and to develop an active model method of the quad-TRUAV. The attitude control method with an innovative smooth-switch structure is another contribution to flight experiments. Numerical results are displayed to present the experimental results and effectiveness of the proposed nonlinear models.

关键词： tilt-rotor unmanned aerial vehicle flight control nonlinear system identification active model method unscented Kalman filter

Effects of rapid quenching on structure and cycle stability of La-Mg-Ni-Co type hydrogen storage alloy

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Rare Metals 2006年第Z1期25卷 207-212页

作者： DONG Xiaoping Lü Fanxiu ZHANG yanghuan yang liying FENG Meng WANG Xinlin School of Material Science and Engineering University of Science and Technology Beijing Beijing 100083 China Department of Functional Material Research Central Iron and Steel Research Institute Beijing 100081 China School of Material Science and Engineering University of Science and Technology Beijing Beijing 100083 China Department of Functional Material Research Central Iron and Steel Research Institute Beijing 100081 China School of Mateials Inner Mongolia University of Science and Technology Baotou 01401 China School of Material Science and Engineering University of Science and Technology Beijing Beijing 100083 China Department of Functional Material Research Central Iron and Steel Research Institute Beijing 100081 China Department of Functional Material Research Central Iron and Steel Research Institute Beijing 100081 China

In order to improve the cycle stability of La-Mg-Ni-Co type alloy electrode, rapid quenching technology was employed. The effects of rapid quenching on the microstructure and cycle stability of the alloy were investigated. The obtained results show that the La2Mg(Ni0.85Co0.15)9M0.1 (M=B, Cr) alloy electrodes are composed of (La, Mg)Ni3 phase, LaNi5 phase and a small amount of the LaNi2 phase. A trace of the Ni2B phase exists in the as-cast MB alloy, and the Ni2B phase in the alloy nearly disappears after rapid quenching. Rapid quenching technology can slightly improve the cycling life of the alloy. When the quenching rate increases from 0 m·s-1 (As-cast is defined as quenching rate of 0 m·s-1) to 30 m·s-1, the cycle lives of the MB, MCr alloys enhance from 86 and 87 cycles to 106 and 119 cycles, respectively. On the other hand, the average capacity decay rates of the MB, MCr alloys decrease from 1.7172 and 1.7178 mAh·g-1·cycle-1 to 1.5751 and 1.3060 mAh·g-1·cycle-1 after 86 charge-discharges cycling, respectively.

关键词： rapid quenching La-Mg-Ni-Co type hydrogen storage alloy structure characteristics cycle stability

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Editorial

Journal of Data and Information Science 2018年第4期3卷 1-2页

作者： liying yang journal of data and information science center of scientometrics national science librarychinese academy of sciences

For research assessment and for science communities,performance evaluation and resource allocation based on the evaluation are always common and heated *** the controversy of how peer review and metrics working togeth... 详细信息

关键词： Editorial

On c#-normal subgroups in finite groups

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Frontiers of Mathematics in China 2018年第5期13卷 1169-1178页

作者： Huaquan WEI Qiao DAI Hualian ZHANG Yubo LV liying yang College of Mathematics and Information Sciences Guangxi University Nanning 530004 China School of Mathematics and Statistics Guangxi Teachers Education University Nanning 530023 China

A subgroup H of a finite group G is called a c#-normal subgroup of G if there exists a normal subgroup K of G such that G = HK and H n K is a CAP-subgroup of G. In this paper, we investigate the influence of fewer c#- normal subgroups of Sylow p-subgroups on the p-supersolvability, p-nilpotency, and supersolvability of finite groups. We obtain some new sufficient and necessary conditions for a group to be p-supersolvable, p-nilpotent, and supersolvable. Our results improve and extend many known results.

关键词： Finite group c#-normal p-supersolvable p-nilpotent supersolvable