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Flexible Antenna Arrays for Wireless Communications: Modeling and Performance Evaluation

IEEE Transactions on Wireless Communications 2025年第6期24卷 4937-4951页

作者： Yang, Songjie An, Jiancheng Xiu, Yue Lyu, Wanting Ning, Boyu Zhang, Zhongpei Debbah, Merouane Yuen, Chau University of Electronic Science and Technology of China National Key Laboratory of Wireless Communications Chengdu611731 China Nanyang Technological University School of Electrical and Electronics Engineering 639798 Singapore Civil Aviation Flight University of China College of Air Traffic Management Sichuan 618311 China Khalifa University of Science and Technology KU 6G Research Center PO Box 127788 Abu Dhabi United Arab Emirates

Flexible antenna arrays (FAAs), distinguished by their rotatable, bendable, and foldable properties, are extensively employed in flexible radio systems to achieve customized radiation patterns. This paper aims to illustrate that FAAs, capable of dynamically adjusting surface shapes, can enhance communication performances with both omni-directional and directional antenna patterns, in terms of multi-path channel power and channel angle Cramér-Rao bounds. To this end, we develop a mathematical model that elucidates the impacts of the variations in antenna positions and orientations as the array transitions from a flat to a rotated, bent, and folded state, all contingent on the flexible degree-of-freedom. Moreover, since the array shape adjustment operates across the entire beamspace, especially with directional patterns, we discuss the sum-rate in the multi-sector base station that covers the 360° communication area. Particularly, to thoroughly explore the multi-sector sum-rate, we propose separate flexible precoding (SFP), joint flexible precoding (JFP), and semi-joint flexible precoding (SJFP), respectively. In our numerical analysis comparing the optimized FAA to the fixed uniform planar array, we find that the bendable FAA achieves a remarkable 156% sum-rate improvement compared to the fixed planar array in the case of JFP with the directional pattern. Furthermore, the rotatable FAA exhibits notably superior performance in SFP and SJFP cases with omni-directional patterns, with respective 35% and 281%. © 2025 IEEE. All rights reserved.

关键词： Degrees of freedom (mechanics)

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Improving Physical-Layer Security in ISAC-UAV System: Beamforming and Trajectory Optimization

arXiv

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arXiv 2024年

作者： Xiu, Yue Lyu, Wanting Yeoh, Phee Lep Ai, Yi Li, Yonghui Wei, Ning College of Air Traffic Management Civil Aviation Flight University of China Deyang618311 China National Key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of China Chengdu611731 China School of Science Technology and Engineering University of the Sunshine Coast QLD Australia School of Science Technology and Engineering Southwest Jiaotong University Chengdu China School of Electrical and Information Engineering University of Sydney SydneyNSW2006 Australia

This paper investigates a novel unmanned aerial vehicle (UAV) secure communication system with integrated sensing and communications. We consider wireless security enhancement for a multiple-antenna UAV transmitting ISAC waveforms to communicate with multiple ground Internet-of-Thing devices and detect the surrounding environment. Specifically, we aim to maximize the average communication secrecy rate by optimizing the UAV trajectory and beamforming vectors. Given that the UAV trajectory optimization problem is non-convex due to multivariable coupling develop an efficient algorithm based on the successive convex approximation (SCA) algorithm. Numerical results show that our proposed algorithm can ensure the accuracy of sensing targets and improve the communication secrecy rate. Copyright © 2024, The Authors. All rights reserved.

关键词： Unmanned aerial vehicles (UAV)

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Exceptional Points Induced by Time-Varying Mass to Enhance the Sensitivity of Defect Detection

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Physical Review Applied 2022年第6期18卷 064055-064055页

作者： Jinbo Yuan Linlin Geng Jiahui Huang Qiuquan Guo Jun Yang Gengkai Hu Xiaoming Zhou Key Laboratory of Dynamics and Control of Flight Vehicle of Ministry of Education School of Aerospace Engineering Beijing Institute of Technology Beijing 100081 China Shenzhen Institute for Advanced Study University of Electronic Science and Technology of China Shenzhen 518110 China

The exceptional point (EP), a non-Hermitian degeneracy at which eigenvalues and eigenvectors coalesce simultaneously, is investigated in mechanical oscillators involving a time-varying mass. A dynamic modulation mechanism is employed to create the time-varying mass, which can potentially develop an EP by acting as an energy source and drain. To fully demonstrate the existence of EPs, the eigenvalue problem for the modulated system is theoretically formulated through two different schemes, based on the state-space and harmonic balance methods. A second-order EP is confirmed by both methods and exists as a result of the coalescence of fundamental and harmonic eigenmodes. As a salient property of this second-order EP, the square-root behavior of the eigenfrequency subject to small perturbations of the system parameters is theoretically demonstrated, and utilized to devise a proof-of-concept model for mechanical sensors with high sensitivity to void defects in elastic solids. The EP behavior induced by a time-varying mass may find potential applications in damage assessment and health monitoring of engineering structures.

关键词： Acoustic measurements Defects Metrology Acoustic metamaterials Micromechanical devices Non-Hermitean systems PT-symmetry Acoustic techniques

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Treatment of Wall Boundary Conditions in High-Order Compact Gas-Kinetic Schemes

arXiv

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arXiv 2025年

作者： Zhang, Jiawang Ji, Xing Xu, Kun Department of Mathematics Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong State Key Laboratory for Strength and Vibration of Mechanical Structures Shaanxi Key Laboratory of Environment and Control for Flight Vehicle School of Aerospace Engineering Xi’an Jiaotong University Xi’an China Department of Mechanical and Aerospace Engineering Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong Shenzhen Research Institute Hong Kong University of Science and Technology Shenzhen China

The boundary layer represents a fundamental structure in fluid dynamics, where accurate boundary discretization significantly enhances computational efficiency. This paper presents a third-order boundary discretization for compact gas-kinetic scheme (GKS). Wide stencils and curved boundaries pose challenges in the boundary treatment for high-order schemes, particularly for temporal accuracy. By utilizing a time-dependent gas distribution function, the GKS simultaneously evaluates fluxes and updates flow variables at cell interfaces, enabling the concurrent update of cell-averaged flow variables and their gradients within the third-order compact scheme. The proposed one-sided discretization achieves third-order spatial accuracy on boundary cells by utilizing updated flow variables and gradients in the discretization for non-slip wall boundary conditions. High-order temporal accuracy on boundary cells is achieved through the GKS time-dependent flux implementation with multistage multi-derivative methodology. Additionally, we develop exact no-penetration conditions for both adiabatic and isothermal wall boundaries, with extensions to curved mesh geometries to fully exploit the advantages of high-order schemes. Comparative analysis between the proposed one-sided third-order boundary scheme, third-order boundary scheme with ghost cells, and second-order boundary scheme demonstrates significant performance differences for the third-order compact GKS. Results indicate that lower-order boundary cell treatments yield substantially inferior results, while the proposed third-order treatment demonstrates superior performance, particularly on coarse grid configurations. Copyright © 2025, The Authors. All rights reserved.

关键词： Mesh generation

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Enhancing interfacial thermal transport by nanostructures: Monte Carlo simulations with ab initio phonon properties

arXiv

引用

arXiv 2024年

作者： Luo, Wenzhu Wang, Neng Lian, Wenlei Yin, Ershuai Li, Qiang MIIT Key Laboratory of Thermal Control of Electronic Equipment School of Energy and Power Engineering Nanjing University of Science & Technology Jiangsu Nanjing210094 China College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Jiangsu Nanjing210016 China Key Laboratory of Thermal Management and Energy Utilization of Aviation Vehicles Ministry of Industry and Information Technology Jiangsu Nanjing210016 China

Recent experiments have indicated that employing nanostructures can enhance interfacial heat transport, but the mechanism by which different structural morphologies and dimensions contribute to the full-spectrum phonon interfacial transport remains unclear. In this paper, a multiscale method to study the thermal transfer at nanostructured interfaces is developed by combining density functional calculation, Monte Carlo simulation, and diffuse mismatch method. The changes in the transport paths and contributions to thermal conductance of different frequency phonons caused by changes in nanostructure morphology and size are investigated. The results show that, compared to the triangular and trapezoidal nanostructures, the rectangular nanostructures are more beneficial in enhancing the probability of the reflected phonons encountering the interface, and thus the phonon interfacial transmittance. The nanostructure makes the interfacial heat flow extremely heterogeneous, with significant transverse heat flow occurring at the sidewalls, resulting in a new thermal conduction pathway. The phenomena of multiple reflections and double transmission together lead to the existence of the optimal dimension that maximizes the nanostructures enhancement effect on interfacial heat transfer. The optimal nanostructure width is 100 nm when the height is 100 nm and the maximum interfacial thermal conductance enhancement ratio is 1.31. These results can guide the design of heat transfer enhancement structures at the interface of the actual high-power chips. Copyright © 2024, The Authors. All rights reserved.

关键词： Nanostructures

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Combining Arrival-Departure Scheduling with Runway Configuration Mode Switches

Combining Arrival-Departure Scheduling with Runway Configura...

引用

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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Heat transfer enhancement of N-Ga-Al semiconductors heterogeneous interfaces

arXiv

引用

arXiv 2024年

作者： Luo, Wenzhu Yin, Ershuai Wang, Lei Lian, Wenlei Wang, Neng Li, Qiang MIIT Key Laboratory of Thermal Control of Electronic Equipment School of Energy and Power Engineering Nanjing University of Science & Technology Jiangsu Nanjing210094 China College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Jiangsu Nanjing210016 China Key Laboratory of Thermal Management and Energy Utilization of Aviation Vehicles Ministry of Industry and Information Technology Jiangsu Nanjing210016 China

Heat transfer enhancement of N-Ga-Al semiconductor heterostructure interfaces is critical for the heat dissipation in GaN-based electronic devices, while the effect of the AlxGa(1-x)N transition layer component concentration and thickness on the heat transfer mechanism at the GaN-AlN interface is unclear. In this paper, using molecular dynamics simulations based on machine learning potentials, the interfacial thermal conductance (ITC) between GaN-AlxGa(1-x)N, AlN-AlxGa(1-x)N and GaN-AlxGa(1-x)N-AlN heterostructure interfaces are calculated for different transition layer thicknesses with different concentrations of Al fractions, and the reasons for the change of ITC and its heat transfer mechanism were explained by the phonon density of states and the spectral heat current. GaN-AlN heterostructure ITC at 300 K is calculated to be 557 MW/(m2K), and the ITCs of GaN-Al0.5Ga0.5N and AlN-Al0.5Ga0.5N are improved by 128% and 229% compared to GaN-AlN, whereas the ITCs of GaNAl0.7Ga0.3N-AlN containing a 0.5 nm transition layer improved by 27.6%. This is because elemental doping enhances phonon scattering near the interface thereby promoting phonon energy redistribution, but the bulk thermal resistance of the AlxGa(1-x)N layer also increases rapidly with increasing doping ratio, and ITC is affected by a combination of these two factors. This work aims to understand the mechanism of transition layer component concentration and thickness on the heat transfer at the GaN-AlN contact interface, which provides a useful guide for better thermal design of the GaN-AlN heterostructure interface. Copyright © 2024, The Authors. All rights reserved.

关键词： Gallium nitride

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Corrosion Behaviour of 2198 Aluminium-Lithium Alloy in Alternating Wet and Dry Environments

SSRN

引用

SSRN 2024年

作者： Liu, Yingyan Deng, Zhibin Zhang, Qian Hu, Xiao Yue, Hang Tang, Haiping Li, Guotao Civil Aviation Flight University of China Guanghan618307 China Civil Aircraft Fire Science and Safety Engineering Key Laboratory of Sichuan Province Guanghan618307 China Sichuan Key Technology Engineering Research Center for All-electric Navigable Aircraft Guanghan618307 China Petrochina Company Limited Yunnan671000 China

The corrosion behavior and mechanisms of 2198 aluminum-lithium alloy under alternating wet-dry conditions in a simulated marine atmospheric environment were investigated using weight loss measurement, electrochemical impedance spectroscopy (EIS), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), macroscopic morphology analysis, 3D profilometry, and X-ray photoelectron spectroscopy (XPS). The results indicate that corrosion weight loss increases with decreasing wet-to-dry ratios, accompanied by an increase in the corrosion rate. Various data suggest that the primary corrosion products are composed of Al2O3, AlO(OH), and AlCl3. The reduction in the wet-to-dry ratio leads to the enrichment of Cl⁻ within the corrosion products, extending the contact time between the substrate and the medium, thereby intensifying the hydrolysis of Al³⁺. This exacerbates the dissolution at pitting sites, which in turn erodes and breaks down the corrosion product film, accelerating the overall corrosion process. © 2024, The Authors. All rights reserved.

关键词： Electrochemical impedance spectroscopy

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Automation 5.0: The key to Systems Intelligence and Industry 5.0

引用

IEEE/CAA Journal of Automatica Sinica 2024年第8期11卷 1723-1727页

作者： Ljubo Vlacic Hailong Huang Mariagrazia Dotoli Yutong Wang Petros A.Ioannou Lili Fan Xingxia Wang Raffaele Carli Chen Lv Lingxi Li Xiaoxiang Na Qing-Long Han Fei-Yue Wang Institute of Intelligent and Integrated Systems and the School of Engineering and Built Environment Griffith UniversityNathanQLD 4111Australia Department of Aeronautical and Aviation Engineering The Hong Kong Polytechnic UniversityHong KongChina Department of Electrical and Information Engineering Polytechnic of Bari70126 BariItaly State Key Laboratory of Multimodal Artificial Intelligence Systems Institute of AutomationChinese Academy of SciencesBeijing 100190and also with the Qingdao Academy of Intelligent IndustriesQingdao 266114China Department of Electrical Engineering-Systems University of Southern CaliforniaLos AngelesCA 90007 USA School of Automation Beijing Institute of TechnologyBeijing 100081China State Key Laboratory of Multimodal Artificial Intelligence Systems Institute of AutomationChinese Academy of SciencesBeijing 100190 School of Artificial Intelligence University of Chinese Academy of SciencesBeijing 100049 Beijing Huairou Academy of Parallel Sensing Beijing 101499China School of Mechanical and Aerospace Engineering Nanyang Technological UniversitySingapore 639798Singapore Department of Electrical and Computer Engineering Purdue School of Engineering and TechnologyIndiana University-Purdue University IndianapolisIndianapolisIN 46202 USA Department of Engineering University of CambridgeCB21TN CambridgeU.K. School of Science Computing and Engineering TechnologiesSwinburne University of TechnologyMelbourne VIC 3122Australia State Key Laboratory for Management and Control of Complex Systems Chinese Academy of SciencesBeijing 100190 School of Artificial Intelligence University of Chinese Academy of SciencesBeijing 100049China Dazhou Artificial Intelligence Institute Dazhouand the Faculty of Innovation EngineeringMacao University of Science and TechnologyMacao 999078China

AUTOMATION has come a long way since the early days of mechanization,i.e.,the process of working exclusively by hand or using animals to work with *** rise of steam engines and water wheels represented the first generation of industry,which is now called Industry Citation:***,***,***,***,***,***,***,***,***,***,***,Q.-***,and F.-***,“Automation 5.0:The key to systems intelligence and Industry 5.0,”IEEE/CAA ***,vol.11,no.8,pp.1723-1727,Aug.2024.

关键词： Automation machinery intelligence

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Effect of Dry and Wet Cycle Time Ratio on the Corrosion Behavior of 2198 Aluminum-Lithium Alloy

SSRN

引用

SSRN 2024年

作者： Liu, Yingyan Deng, Zhibin Zhang, Qian Lu, Rui Yue, Hang Tang, Haiping Li, Guotao Civil Aviation Flight University of China Guanghan618307 China Civil Aircraft Fire Science and Safety Engineering Key Laboratory of Sichuan Province Guanghan618307 China Sichuan Key Technology Engineering Research Center for All-electric Navigable Aircraft Guanghan618307 China Petrochina Company Limited Yunnan671000 China

The corrosion behavior and mechanisms of 2198 aluminum-lithium alloy under alternating wet-dry conditions in a simulated marine atmospheric environment were investigated using weight loss measurement, electrochemical impedance spectroscopy (EIS), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), macroscopic morphology analysis, 3D profilometry, and X-ray photoelectron spectroscopy (XPS). The results indicate that corrosion weight loss increases with decreasing wet-to-dry ratios, accompanied by an increase in the corrosion rate. Various data suggest that the primary corrosion products are composed of Al2O3 AlO(OH), and AlCl3. The reduction in the wet-to-dry ratio leads to the enrichment of Cl- within the corrosion products, extending the contact time between the substrate and the medium, thereby intensifying the hydrolysis of Al3+. This exacerbates the dissolution at pitting sites, which in turn erodes and breaks down the corrosion product film, accelerating the overall corrosion process. © 2024, The Authors. All rights reserved.

关键词： Electrochemical impedance spectroscopy

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