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Ultra-Broadband Infrared Metamaterial Absorber for Passive Radiative Cooling

中国物理快报（英文版） 2021年第3期38卷 44-49页

作者： Yan-Ning Liu Xiao-Long Weng Peng Zhang Wen-Xin Li Yu Gong Li Zhang Tian-Cheng Han Pei-Heng Zhou Long-Jiang Deng National Engineering Research Center of Electromagnetic Radiation Control Materials University of Electronic Science and Technology of ChinaChengdu 611731China Key Laboratory of Multi-spectral Absorbing Materials and Structures of Ministry of Education University of Electronic Science and Technology of ChinaChengdu 611731China Shenyang Aircraft Design and Research Institute Shenyang 110035China

Infrared metamaterial absorber (MMA) based on metal-insulator-metal (MIM) configuration withflexible design, perfect and selective absorption, has attracted much attention recently for passive radiative cooling applications. To cool objects passively, broadband infrared absorption (i.e. 8–14 μm) is desirable to emit thermal energy through atmosphere window.

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Development and global validation of a 1-week-old piglet head finite element model for impact simulations

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Chinese Journal of Traumatology 2023年第3期26卷 147-154页

作者： Zhong-Qing Su Da-Peng Li Rui Li Guang-Liang Wang Lang Liu Ya-Feng Wang Ya-Zhou Guo Zhi-Gang Li School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBejing100044China D epartment of NeurosurgeryBejing Children's Hospital CapitalMedical University.National CenterforChildren'sHealthBeijing 100045China Aviation Key Laboratory of Science and Technology on Structures Impact Dynamics China Aircraft Strength Research InstituteXi'an70065China

Purpose:Child head injury under impact scenarios(***,vehicle crashes,etc.)is an important topic in the field of injury *** head of piglet was commonly used as the surrogate to investigate the biomechanical response and mechanisms of pediatric head injuries because of the similar cellular structures and material ***,up to date,piglet head models with accurate geometry and material properties,which have been validated by impact experiments,are *** aim to develop such a model for future ***:In this study,first,the detailed anatomical structures of the piglet head,including the skull,suture,brain,pia mater,dura mater,cerebrospinal fluid,scalp and soft tissue,were constructed based on CT ***,a structured butterfly method was adopted to mesh the complex geometries of the piglet head to generate high-quality elements and each component was assigned corresponding constitutive material ***,the guided drop tower tests were conducted and the force-time histories were ectracted to validate the piglet head finite element ***:Simulations were conducted on the developed finite element model under impact conditions and the simulation results were compared with the experimental data from the guided drop tower tests and the published *** average peak force and duration of the guide drop tower test were similar to that of the simulation,with an error below 10%.The inaccuracy was below 20%.The average peak force and duration reported in the literature were comparable to those of the simulation,with the exception of the duration for an impact energy of 11 *** results showed that the model was capable to capture the response of the pig ***:This study can provide an effective tool for investigating child head injury mechanisms and protection strategies under impact loading conditions.

关键词： Piglet head Finite element model Dynamic response Validation Drop tower tests

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Effect of Ambient Pressure on the Fire Characteristics of Lithium-Ion Battery Energy Storage Cabin

SSRN

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SSRN 2024年

作者： Wang, Zhi Song, Yuchen Yin, Bo Shia, Bobo An, Weiguang Li, Zhihua School of Safety Engineering China University of Mining and Technology Xuzhou China Civil Aircraft Fire Science and Safety Engineering Key Laboratory of Sichuan Province Guanghan China Jiangsu Engineering Research Center for Dust Control and Occupational Protection China University of Mining and Technology Xuzhou China Jiangsu Key Laboratory of Fire Safety in Urban Underground Space China University of Mining and Technology Xuzhou China Jiangsu I-safe Energy Co. Ltd Wuxi China

With the popularity and application of lithium-ion battery energy storage at high altitudes, the potential evolution of fire risk in lithium-ion battery storage cabins remains uncertain. In this study, numerical simulation is employed to investigate the fire characteristics of lithium-ion battery storage cabin under varying ambient pressures. The findings reveal that the peak heat release rate of fires in atmospheric pressure is significantly higher than that in low-pressure. Specifically, the heat release rate at atmospheric pressure is 9215 kW, which exceeds the value at low pressure by 42%, only accounting to 3900 kW. And this peak heat release rate exhibits a power function relationship with ambient pressure. However, fires tend to last longer in low-pressure. In addition, as the ambient pressure decreases, the range of high-temperature areas expands and the speed of spread increases. And higher peak concentrations of CO and CO2 is produced at atmospheric pressure. The results also indicate that smoke spreads more rapidly in low-pressure, although with a decrease in peak smoke concentration as ambient pressure decreases. The study findings can serve as a foundation for assessing the fire hazards and designing fire protection measures for lithium-ion battery storage cabins exposed to varying ambient pressures. © 2024, The Authors. All rights reserved.

关键词： Lithium-ion batteries

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Distributed time-varying formation control with uncertainties based on an event-triggered mechanism

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science China(Information sciences) 2021年第3期64卷 167-176页

作者： Xiaoduo LI Yumeng BAI Xiwang DONG Qingdong LI Zhang REN Science and Technology on Aircraft Control Laboratory School of Automation Science and Electrical EngineeringBeihang University Department of Electrical and Computer Engineering University of Wisconsin-Madison Beijing Advanced Innovation Center for Big Data and Brain Computing Beihang University

This paper investigates the distributed time-varying formation(TVF) problems for general linear multi-agent systems(MASs) subject to matched bounded uncertainties based on an adaptive event-triggered mechanism. A TVF protocol was designed with an event-triggered mechanism by introducing adaptive weights into the formation control protocol and triggering condition, and the large chattering phenomenon was avoided by the σ-modification adaptive law. According to the Lyapunov stability theory, proof has been established that the MASs in the presence of uncertainties can realize the expected formation that satisfies the given feasible condition. Finally, an example is provided to verify the effectiveness of the proposed algorithm.

关键词： formation control multi-agent systems event-triggered adaptive control

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Accurate Output Tracking control for Nonminimum Phase Systems via An Iterative Redefinition-based Method with aircraft Application

Accurate Output Tracking Control for Nonminimum Phase System...

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第34届中国控制与决策会议

作者： Weihao Li Yang Zhu Bo Zhu Kaiyu Qin Mengji Shi School of Aeronautics and Astronautics University of Electronic Science and Technology of China Aircraft Swarm Intelligent Sensing and Cooperative Control Key Laboratory of Sichuan Province School of Information Science and Technology Southwest Jiaotong University School of Aeronautics and Astronautics Sun Yat-Sen University

This paper provides an insight into the accurate output tracking control for non-minimum phase(NMP)systems.A novel iterative redefinition-based approach is proposed to overcome the inherent drawbacks of classic outputredefinition ***,a feasible minimum phase(MP) output is first identified by the output *** the desired output trajectory is iteratively redefined such that the state references for the new MP system could approximate those for the original NMP system within arbitrarily small *** the redefined reference signals,a controller in a "feedforward + feedback" configuration is employed to simultaneously achieve the accurate tracking of output trajectory and the stabilizing of internal *** application of this control framework to F-16 aircraft is presented,which is further verified by numerical simulations,showing significant performance improvement by the proposed output reference iterative redefinition algorithm.

关键词： Non-minimum Phase System Iterative Redefinition Output Redefinition Stable Inversion

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Distributed Nash equilibrium seeking for non-cooperative convex games with local constraints

Distributed Nash equilibrium seeking for non-cooperative con...

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第40届中国控制会议

作者： Fei Liu Qing Wang Yongzhao Hua Xiwang Dong Zhang Ren School of Automation Science and Electrical Engineering Science and Technology on Aircraft Control LaboratoryBeihang University Institute of Artificial Intelligence Beihang University

This paper considers the problem of Nash equilibrium seeking in non-cooperative convex games subjected to local constraints including both equality and inequality constraints. Each player in the game is individually associated with a local objective function, which is coupled with the actions of the other players. The players cannot observe the actions of the players that are not their neighbors. Instead, the players are capable of exchanging information of actions via an undirected and connected communication graph. Thus, a leader-following consensus-based estimation of actions of the players is conducted. Furthermore, a Nash equilibrium seeking algorithm is proposed. Stability analysis by means of continuous time Lyapunov approach is presented and it is shown that the algorithm is capable of achieving global convergence to the Nash equilibrium. A numerical example is given to verify the effectiveness of the results of the paper.

关键词： Leader-following consensus Nash equilibrium non-cooperative games local constraints

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Hierarchical Pooling Based Extreme Learning Machine for Image Classification

Hierarchical Pooling Based Extreme Learning Machine for Imag...

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Chinese Intelligent Systems Conference, CISC 2019

作者： Liu, Yan Liu, Zhi Lei, Zhirong Hengxiang Control Technology Company Limited Xi’an China School of Artificial Intelligence Xidian University Xi’an China National Key Laboratory of Science and Technology on Aircraft Control FACRI Xi’an China

ISBN: (纸本)9789813296978

In this paper, a Hierarchical Pooling based Extreme Learning Machine (HPELM) is proposed for image classification. Extreme Learning Machine based on Local Receptive Fields (ELM-LRF) has been proved to be powerful for image classification. However, ELM-LRF is a shallow network and the features extracted by ELM-LRF is low-level. To obtain better results, one need to enlarge the dimension of the hidden features. This paper extends the concept of deep learning to ELM-LRF. Random convolutional nodes and hierarchical pooling structures are constructed for capturing high level semantic features. HPELM has the ability of feature extraction and classification. It improves the classification performance of ELM-LRF without increasing the number of the neuron in the last hidden layer. Experiments on the MNIST and NORB datasets demonstrate the attractive performance of HPELM even compared with the state-of-the-art algorithms. © 2020, Springer Nature Singapore Pte Ltd.

关键词： Image classification

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Combining Arrival-Departure Scheduling with Runway Configuration Mode Switches

Combining Arrival-Departure Scheduling with Runway Configura...

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IEEE International Conference on Civil Aviation Safety and Information technology (ICCASIT)

作者： Chaoyu Xia Zhenya Wu Chunrong Yang Changbo Hou Chunbo Guo The 2-nd Research Institute Civil Aviation Administration of China Chengdu China Civil Unmanned Aircraft Traffic Management Key Laboratory of Sichuan Province Chengdu China Chengdu Civil Aviation Air Trafc Control Science and Technology Co. Ltd Chengdu China

In this paper, we reformulate the aircraft scheduling problem as a mixed integer linear program (MILP) over runway configuration mode switches, under mixed operations with the objective of minimizing total delay. Furthermore, some appropriate wake vortex separation constraints is established, including Arrival-Arrival, Departure-Departure, Arrival-Departure, and Departure-Arrival for the different combinations. The performance of the proposed method is verified by experimentation with flight plans collected from the official database, which ensures research reliability.

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Theory and Experiment on Distributed Output Formation Tracking of Unmanned Aerial and Ground Vehicle Swarm Systems Over Jointly Connected Digraphs

SSRN

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SSRN 2024年

作者： Shu, Peixuan Wang, Changhai Hua, Yongzhao Dong, Xiwang Liu, Yumeng Ren, Zhang School of Automation Science and Electrical Engineering Science and Technology on Aircraft Control Laboratory Beihang University Beijing100191 China Shenyuan Honors College Beihang University Beijing100191 China Institute of Artificial Intelligence Beihang University Beijing100191 China Institute of Unmanned System Beihang University Beijing100191 China Institute of Software Chinese Academy of Sciences Beijing100190 China

This paper studies the distributed output formation tracking control problem of the unmanned aerial vehicle (UAV) and unmanned ground vehicle (UGV) swarm systems, where the UAV swarm cooperatively tracks the output trajectory of the UGV in a formation under directed jointly connected communication networks. A three-layer formation tracking protocol is proposed. Firstly, a novel distributed observer using neighbor interactions is designed for each UAV to estimate the states of the UGV with parameterized inputs over periodic jointly connected digraphs. Next, based on the observation result and output regulation theory, a virtual reference system that tracks the trajectory of the UGV in the desired formation is constructed to generate reference states for each UAV. Then based on the differential flatness of UAVs, a geometric controller is utilized for UAVs to track the reference states and form the formation. An algorithm to determine the gain matrices of the protocol is also presented while the convergence of the system is analyzed. Finally, an experiment platform with three quadrotor UAVs and one UGV is built. The effectiveness of the proposed protocol is validated both by the simulation and experiment. © 2024, The Authors. All rights reserved.

关键词： Ground vehicles

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An improved event-trigger-based robust 6-DOF spacecraft formation control scheme under restricted communication

An improved event-trigger-based robust 6-DOF spacecraft form...

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Chinese Automation Congress (CAC)

作者： Yan Liu Kaiyu Qin Mengji Shi Lu Cao Weihao Li Boxian Lin School of Aeronautics and Astronautics University of Electronic Science and Technology of China Chengdu China Aircraft Swarm Intelligent Sensing and Cooperative Control Key Laboratory of Sichuan Province Chengdu China National Innovation Institute of Defense Technology Chinese Academy of Military Science Beijing China

This paper addresses the robust six-degree-of-freedom (6-DOF) formation control problem for groups of spacecraft with constraints that include: restricted communication, unknown external perturbations, model uncertainties, and attitude orbit coupling. First, a Zeno-free trigger function is presented based on the event trigger mechanism to avoid continuous communication and save bandwidth resources; Then, the RBF neural networks are adopted to approximate the model uncertainties and external perturbations of the system; Furthermore, a distributed robust formation controller is designed and the coupling between the event trigger mechanism and neural networks is analyzed, and by designing Lyapunov functions, it is theoretically demonstrated that the formation error of spacecraft can converge to an arbitrarily small residual set. Finally, the simulation experiments are given to validate that the combination of the time-triggered mechanism and neural networks can effectively reduce the number of system controller updates, save communication bandwidth resources and weaken the impact of uncertainties on system stability.

关键词： Space vehicles Couplings Uncertainty Attitude control Perturbation methods Neural networks Bandwidth

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