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Docking control for probe-drogue refueling: An additive-state-decomposition-based output feedback iterative learning control method

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Chinese Journal of Aeronautics 2020年第3期33卷 1016-1025页

作者： Jinrui REN Quan QUAN Cunjia LIU kai-Yuan cai School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100083China Department of Aeronautical and Automotive Engineering Loughborough UniversityLeicestershire LE113TUUnited Kingdom

Designing a controller for the docking maneuver in Probe-Drogue Refueling(PDR) is an important but challenging task, due to the complex system model and the high precision *** order to overcome the disadvantage of only feedback control, a feedforward control scheme known as Iterative Learning Control(ILC) is adopted in this ***, Additive State Decomposition(ASD) is used to address the tight coupling of input saturation, nonlinearity and the property of Non Minimum Phase(NMP) by separating these features into two subsystems(a primary system and a secondary system).After system decomposition, an adjoint-type ILC is applied to the Linear Time-Invariant(LTI) primary system with NMP to achieve entire output trajectory tracking, whereas state feedback is used to stabilize the secondary system with input *** two controllers designed for the two subsystems can be combined to achieve the original control goal of the PDR ***, to compensate for the receiverindependent uncertainties, a correction action is proposed by using the terminal docking error,which can lead to a smaller docking error at the docking *** tests have been carried out to demonstrate the performance of the proposed control method, which has some advantages over the traditional derivative-type ILC and adjoint-type ILC in the docking control of PDR.

关键词： Additive state decomposition Adjoint operator Docking control Iterative learning control Probe-drogue refueling Stable inversion

Structural and electrical properties of high Curie temperature Aurivillius phase composite ceramics with largely enhanced piezoelectricity

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Science China(Technological Sciences) 2016年第7期59卷 1048-1053页

作者： WANG YunLi cai kai MA JingTao ZENG Fei GUO Dong Institute of Acoustics Chinese Academy of Sciences Beijing 100190 China Beijing Center for Physical and Chemical Analysis Beijing 100089 China School of Materials Science & Engineering Tsinghua University Beijing 100084 China School of Materials Science & Engineering Beihang University Beijing 100191 China

High performance piezoelectric ceramics with high Curie temperatures(TC) are the bottle necks of relevant high temperature devices. In this study, the electrical performance and microstructure of Li and Mn codoped Aurivillius-type composite ceramics with a composition Ca_(0.99-x_Bi_(6.99+x)(Li Mn)_(0.01) Nb Ti_5O_(24)(x = 0–0.8) were systematically investigated. The results indicated that uniform intergrowth structure with a lattice similar to that of the end member CBT could be formed at a low x value(x < 0.4). Phase separation occurred when more A-site Ca^(2+) ions were replaced by Bi^(3+) ions. Nevertheless, all composite samples showed d_(33) values about 2 to 3 times of that of the constituent phase Ca Bi_4Ti_4O_(15) and Bi_3 Ti NbO_9 with still a high depolarization temperature. The performance of the samples was found to be related to the density and larger lattice distortion along the polarization a axis. The results also demonstrated that formation of the compound system was an effective way in improving the performance of Aurivillius-type high TC piezoelectric ceramics.

关键词： piezoelectric ceramics Curie temperature ferroelectricity dielectric properties

Warehouse automation by logistic robotic networks:a cyber-physical control approach

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Frontiers of Information Technology & Electronic Engineering 2020年第5期21卷 693-704页

作者： kai cai Department of Electrical and Information Engineering Osaka City UniversityOsaka 558-8585Japan

In this paper we provide a tutorial on the background of warehouse automation using robotic networks and survey relevant work in the *** present a new cyber-physical control method that achieves safe,deadlock-free,efficient,and adaptive behavior of multiple robots serving the goods-to-man logistic operations.A central piece of this method is the incremental supervisory control design algorithm,which is computationally scalable with respect to the number of ***,we provide a case study on 30 robots with changing conditions to demonstrate the effectiveness of the proposed method.

关键词： Discrete-event systems Cyber-physical systems Robotic networks Warehouse automation Logistics

Hot Ductility of Ti-V Bearing Microalloyed Steel in Continuous Casting

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Journal of Iron and Steel Research International 2014年第4期21卷 451-458页

作者： Yan-hui SUN Ya-nan ZENG kai-ke cai Metallurgical and Ecological Engineering School University of Science and Technology Beijing

Hot ductility of Ti-V bearing steel was studied by theoretical calculation and thermal simulation experi ment. Meanwhile, microsegregation and precipitates were analyzed. The results showed that elements S, Ti and O were enriched at the grain boundaries, while the hot ductility was deteriorated by inclusions of （Fe, Mn, Si, Al）（S, O） in the interdendritic region. At tbe temperature of 1 100℃, large TiN particles had little effect on hot ductility. In the temperature range from 975 to 925 ℃, reduction of area （R. A） declined rapidly from 81. 88% to 63.16% with the size of particles decreasing from 40 to 20 nm and quantity increasing from 1.4 to 11.9 μm 2, respectively. In the temperature range from 875 to 825℃, R. A reduced unobviously from 35.14% to 28.6% with ferric films thickening gradually. The critical stress, 88.79 MPa, was equal to tensile strength at 825℃. Intergranular fracture was easy to occur with higher critical stress below 825℃.

关键词： hot ductility microalloyed steel solute segregation precipitate critical stress

Formation mechanism and control of MgO·Al_2O_3 inclusions in non-oriented silicon steel

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International Journal of Minerals,Metallurgy and Materials 2014年第11期21卷 1068-1076页

作者： Yan-hui Sun Ya-nan Zeng Rui Xu kai-ke cai School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

On the basis of the practical production of non-oriented silicon steel, the formation of Mg O·Al2O3 inclusions was analyzed in the process of ＂basic oxygen furnace（BOF） → RH → compact strip production（CSP）＂. The thermodynamic and kinetic conditions of the formation of Mg O·Al2O3 inclusions were discussed, and the behavior of slag entrapment in molten steel during RH refining was simulated by computational fluid dynamics（CFD） software. The results showed that the Mg O/Al2O3 mass ratio was in the range from 0.005 to 0.017 and that Mg O·Al2O3 inclusions were not observed before the RH refining process. In contrast, the Mg O/Al2O3 mass ratio was in the range from 0.30 to 0.50, and the percentage of Mg O·Al2O3 spinel inclusions reached 58.4% of the total inclusions after the RH refining process. The compositions of the slag were similar to those of the inclusions; furthermore, the critical velocity of slag entrapment was calculated to be 0.45 m·s^-1 at an argon flow rate of 698 L·min^-1, as simulated using CFD software. When the test steel was in equilibrium with the slag, [Mg] was 0.00024wt%–0.00028wt% and [Al]s was 0.31wt%–0.37wt%; these concentrations were theoretically calculated to fall within the Mg O·Al2O3formation zone, thereby leading to the formation of Mg O·Al2O3 inclusions in the steel. Thus, the formation of Mg O·Al2O3 inclusions would be inhibited by reducing the quantity of slag entrapment, controlling the roughing slag during casting, and controlling the composition of the slag and the Mg O content in the ladle refractory.

关键词： silicon steel steelmaking inclusions deoxidation slag entrapment thermodynamics kinetics

Additive-state-decomposition-based station-keeping control for autonomous aerial refueling

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Science China(Information Sciences) 2021年第11期64卷 240-242页

作者： Jinrui REN Quan QUAN Haibiao MA kai-Yuan cai School of Automation Science and Electrical Engineering Beihang University

Dear editor,Aerial refueling(AR) is an effective method of increasing the endurance and range of aircraft by refueling them in flight [1, 2]. Station-keeping control is the basis of autonomous aerial refueling(AAR). The station-keeping control for AAR is a difficult task for two main reasons. First,the receiver is disturbed by the atmospheric turbulence and the wake vortex of the tanker. Secondly, owing to the fuel injection in the refueling process, the mass and the center of mass of the receiver will change.

关键词： Aerial refueling station keeping two-degree-of-freedom additive state decomposition varying mass

Importance of metal location in M-H zeolite for synergistically catalyzing dimethyl ether carbonylation

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Chinese Journal of Chemical Engineering 2022年第1期35卷 350-357页

作者： Shiyue Li Shouying Huang kai cai Ying Li Jing Lv Xinbin Ma Key Laboratory for Green Chemical Technology of Ministry of Education Collaborative Innovation Center of Chemical Science and EngineeringSchool of Chemical Engineering and TechnologyTianjin UniversityTianjin 300350China

Mordenite(MOR)has shown great potential to catalyze dimethyl ether(DME)carbonylation to methyl acetate(MA)in *** synergy between metal species and Brønsted acid sites accelerates DME *** we designed and prepared two catalysts with different Ag locations by seed-directed growth method and two-step impregnation method(named as Ag@HMOR and Ag/HMOR-out,respectively),to explain the effect of Ag location on catalytic *** results of TEM,XPS,CO-IR and UV–Vis showed that Ag species mainly presented as Ag^(0) species over both Ag@HMOR and Ag/***,Ag^(0) species mainly located in the micropores of Ag@HMOR,while as for Ag/HMOR-out,Ag^(0) mainly existed on external *** comparing the performance of the catalysts with different Ag positions,we confirmed that the Ag^(0) species encapsulated in the channels of HMOR promoted the DME carbonylation,which revealed the importance of spatial adjacency on the acid-metal catalysts.

关键词： Dimethyl ether Carbonylation Silver modification Metal location

Distributed On-line Path Planner for Multi-UAV Coordination Using Bi-level Programming

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Distributed On-line Path Planner for Multi-UAV Coordination ...

A density functional theory study on the mechanism of dimethyl ether carbonylation over heteropolyacids catalyst

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作者： Wei Liu Zheng Zheng kai-Yuan cai School of Automation Science and Electrical Engineering Beihang University Science and Technology on Aircraft Control Laboratory Beihang University Xi'an High Technology Institute

ISBN: (纸本)9781467355339

This paper presents a novel on-line path planner for multiple UAVs based on the distributed planning scheme and the bi-level programming technique, in the presence of diverse surface-to-air missiles （SAMs） deployed within large operational spaces. With a formal problem formulation, the planner offers a hierarchical architecture that not only provides global convergence and optimized solution for the UAV team, but also guarantees the path safety and navigability for each UAV according to their respective requirements. Constraints with respect to complex threat environment avoidance, UAVs’ physical attributes and real-time capabilities of airborne equipment are all fully considered in the planning procedure. Simulation results prove that the proposed planner is capable of generating synthetically optimal flight paths for multi-UAV, along with the path safety and smoothness improvement in local for each individual UAV.

关键词： Cooperative Path Planning Unmanned Aerial Vehicles Multi-UAV Bi-level Programming

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Frontiers of Chemical Science and Engineering 2021年第2期15卷 319-329页

作者： kai cai Ying Li Hongbao Shen Zaizhe Cheng Shouying Huang Yue Wang Xinbin Ma Key Laboratory for Green Chemical Technology of Ministry of Education Collaborative Innovation Center of Chemical Science and EngineeringSchool of Chemical Engineering and TechnologyTianjin UniversityTianjin 300350China

Dimethyl ether(DME)carbonylation is considered as a key step for a promising route to produce ethanol from ***(HPAs)are proved to be efficient catalysts for DME *** this work,the reaction mechanism of DME carbonylation was studied theoretically by using density functional theory calculations on two typical HPA models(HPW,HSiW).The whole process consists of three stages:DME dissociative adsorption,insertion of CO into methoxyl group and formation of product methyl *** activation barriers of all possible elementary steps,especially two possible paths for CO insertion were calculated to obtain the most favorable reaction mechanism and rate-limiting ***,the effect of the acid strength of Brønsted acid sites on reactivity was studied by comparing the activation barriers over HPW and HSiW with different acid strength,which was determined by calculating the deprotonation energy,Mulliken population analyses and adsorption energies of pyridine.

关键词： dimethyl ether carbonylation mechanism heteropolyacids density functional theory