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arXiv 2024年

作者： Lyu, Wanting Yang, Songjie Xiu, Yue Chen, Xinyi Zhang, Zhongpei Assi, Chadi Yuen, Chau National Key Laboratory of Wireless Communications University of Electronic Science and Technology of China Chengdu611731 China College of Air Traffic Civil Aviation Flight University of China Guanghan618311 China Concordia University MontrealQCH3G 1M8 Canada The School of Electrical and Electronics Engineering Nanyang Technological University 639798 Singapore

A dual-robust design of beamforming is investigated in an integrated sensing and communication (ISAC) system. Existing research on robust ISAC waveform design, while proposing solutions to imperfect channel state information (CSI), generally depends on prior knowledge of the target’s approximate location to design waveforms. This approach, however, limits the precision in sensing the target’s exact location. In this paper, considering both CSI imperfection and target location uncertainty, a novel framework of joint robust optimization is proposed by maximizing the weighted sum of worst-case data rate and beampattern gain. To address this challenging problem, we propose an efficient two-layer iteration algorithm based on S-Procedure and convex hull. Finally, numerical results verify the effectiveness and performance improvement of our dual-robust algorithm, as well as the trade-off between communication and sensing performance. Copyright © 2024, The Authors. All rights reserved.

关键词： Optimization

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Interaction between Double Solitons in Anti-Pt Symmetric Synthetic Photonic Lattices

SSRN

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SSRN 2022年

作者： Yue, Yazhou Li, Jun Zhang, Zhiqing Gao, Tianxiang Wen, Zengrun Wang, Haohao Qi, Xinyuan Flight Automatic Control Research Institute Xi’an710065 China National Key Laboratory of Science and Technology on Aircraft Control Xi’an710065 China School of Physics Northwest University Xi’an710127 China Shandong Provincial Key Laboratory of Optics and Photonic Devices College of Physics and Electronics Shandong Normal University Jinan250014 China

An anti-parity-time symmetry (anti-PT symmetric) double fiber loop synthetic photonic lattice is constructed theoretically by projecting the intensity of two loops and adjusting the phase and gain/loss distribution. Numerical studies on pulse dynamics show that the trajectories of double-pulse solitons may be maniputlated by tuning the initial relative phases, pulse separation, nonlinearity, and non-Hermitian characteristics of the system. Our research may provide a new way to realize logic gate devices and optical switches in optical interconnection and optical communications. © 2022, The Authors. All rights reserved.

关键词： Optical lattices

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In-Depth Insight into the Inhibition Mechanism in Iron-Based Composites with Bifunction of Anti-Corrosion and Electromagnetic Wave Absorption Based on Experiments and Theoretical Calculations

SSRN

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SSRN 2024年

作者： Jiang, Xianyu Xie, Jianliang Yin, Liangjun Peng, Jian Li, Jianxiao Jiang, Xian yu Zhang, Min Deng, Longjiang Jing, Zhi Qin, Huanyu Zhang, Linbo Zhang, Peng Yuan, Le National Engineering Research Center of Electromagnetic Radiation Control Materials Key Laboratory of Multi-spectral Absorbing Materials and Structures of Ministry of Education University of Electronic Science and Technology of China 2006 Xiyuan Road Chengdu611731 China Shenyang Aircraft Design and Research Institute Aviation Industry Corporation of China Ltd Shenyang110034 China School of Materials Science and Engineering Xihua University Sichuan Chengdu610039 China

The design of anti-corrosive magnetic metal microwave-absorbing materials is crucial for enhancing the environmental compatibility and service life of military objectives in practical applications. Herein, CI@BTSA@OTMS composites were synthesized using an improved sol-gel method with 2-benzothiazolylthio-succinic acid (BTSA) and trimethoxy (octadecyl) silane (OTMS) as precursor materials. The corrosion resistance mechanisms were investigated in both experimental research and theoretical calculations. Electrochemical experimental results affirmed that the CI@BTSA@OTMS composites exhibited exceptional anti-corrosion with the corrosion potential (Ecorr) shifted positively to 0.05 V, the corrosion current (Icorr) exhibited a low level, measuring only 1.1 × 10−7 A/ cm−2, and the protection efficiency attained 99.91%. The CI@BTSA@OTMS composites exhibited a higher non-wetting property with a contact angle of 138.9°. After 480 hours of exposure in a natural salt spray test, the composites still retained relatively intact morphological and compositional characteristics. These results can be attributed to the effective inhibition of corrosive species' proximity due to the spatial isolation and barrier effects, preventing the formation of an electrochemical corrosion circuit. Moreover, simulations and calculations are employed for revealing the diffusion and inhibition mechanisms of corrosive media. For electromagnetic performance, the introduction of organic layer BTSA@OTMS contributed to improve impedance matching in magnetic metal microwave absorbers. © 2024, The Authors. All rights reserved.

关键词： Corrosion resistance

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Sliding Mode Observation and control for Overhead Cranes with Varying Rope Length

Sliding Mode Observation and Control for Overhead Cranes wit...

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2021 China Automation Congress, CAC 2021

作者： Huan, Xuwei Niu, Dan Li, Qi Yang, Jun Liu, Guoyao Chen, Xisong Xiao, Xi Key Laboratory of Measurement and Control of CSE Ministry of Education Southeast University Nanjing China Department of Aeronautical and Automotive Engineering Loughborough University LoughboroughLE11 3TU United Kingdom Nanjing Sciyon Automation Group Co. Ltd Nanjing China Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing China

ISBN: (纸本)9781665426473

This paper proposes a state observer and controller based on the second-order sliding mode scheme for underactuated overhead cranes with load hoisting and lowering. The designed state observer can effectively estimate the uncertainly and unmodeled dynamics of crane systems, and provide appropriate driving force compensations for the sliding mode controller designed by coupling the load swing angle. This guarantees an accurate load positioning and residual swing elimination. Based on the Lyapunov stability criterion, the asymptotic stability of the control system is proved Several simulations are implemented to verify the effectiveness and robustness of the proposed controller for anti-sway and positioning controls. © 2021 IEEE

关键词： Asymptotic stability

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Multiple α sub-variants and anisotropic mechanical properties of an additively-manufactured Ti-6Al-4V alloy

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Journal of Materials science & technology 2021年第11期70卷 113-124页

作者： Yinling Zhang Zhuo Chen Shoujiang Qu Aihan Feng Guangbao Mi Jun Shen Xu Huang Daolun Chen School of Materials Science and Engineering Tongji UniversityShanghai 201804China Department of Mechanical and Industrial Engineering Ryerson UniversityTorontoOntario M5B 2K3Canada Aerospace Hiwing(Harbin)Titanium Industrial Co. Ltd.Harbin High Tech ZoneHarbin 150028China Shanghai Key Lab.of D&A for Metal-Functional Materials School of Materials Science&EngineeringTongji UniversityShanghai 201804China Aviation Key Laboratory of Science and Technology on Advanced Titanium Alloys AECC Beijing Institute of Aeronautical MaterialsBeijing 100095China College of Mechatronics and Control Engineering Shenzhen UniversityShenzhen 518060China

Additive manu facturing(AM)is a promising material processing method which gains significant momentum in the aerospace and biomedical ***,the anisotropy in the mechanical properties of additively-manufactured materials is still poorly *** study was aimed at elucidating crystallographic feature-anisotropy-mechanical property relationship for a Ti-6Al-4V alloy manufactured via selective electron beam melting(SEBM).Abundantαlamellae with six variants were present inside the columnar prior-βgrains with a<100>fiber texture duringβ→αphase *** sixαvariants followed the Burgers orientation relationship of{110}_(β)//{0001}_(α)and<1-11>_(β)//<11-20>_(α).Multiple sub-variants in eachαvariant were observed for the first *** anisotropy in the mechanical properties was mainly related to the relative amount of sixα*** the horizontally-oriented samples had a lower yield strength,they exhibited a higher ductility and longer fatigue life than the vertically-oriented *** softening occurred at higher strain amplitudes,and cyclic stabilization sustained at lower strain *** crack mainly initiated from the specimen surface at lower strain amplitudes,while multiple crack initiation tended to occur at higher strain *** propagation was characterized by fatigue striations along with some secondary cracks.

关键词： Titanium alloy 3D printing Deformation behavior Anisotropy Burgers orientation relationship

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Influence of Different Filling Materials on Stiffness of a New Buffer Bag

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Transactions of Nanjing University of Aeronautics and Astronautics 2021年第1期38卷 106-116页

作者： HOU Yu ZHANG Ming NIE Hong Key Laboratory of Fundamental Science for National Defense-Advanced Design Technology of Flight Vehicle Nanjing University of Aeronautics&AstronauticsNanjing 210016P.R.China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China

A buffer bag mechanism is designed,which can provide axial impact protection under small *** stiffness characteristics of the structure under impact load are *** stiffness of the mechanism and the internal pressure change of the buffer bag are compared and analyzed,when the filling materials are liquid and gas ***,the influence of initial fluid bag pressure,bulk modulus and shell thickness on the stiffness of the mechanism and the change of bag pressure are *** results show that the stiffness of the liquid bag is better than that of the gas bag when the filler is liquid and gas;the liquid bag has obvious pressure rise after the mechanism is subjected to axial force by 300 kN,and the gas bag has almost no pressure rise;the change of bulk modulus,which is1000,1500,2000 and 2500 MPa,has an obvious effect on the liquid bag,and it is positively correlated with the stiffness of the *** change of gas modulus,which is 28 and 44,has little effect on the stiffness of the mechanism;the thickness of the buffer bag,which is 5,10 and 15 mm,also has an obvious effect on the *** stiffness of the liquid bag is greater,and the protection for flexible joint is better in the same condition.

关键词： buffer bag flexible joint axial protection liquid bag gas bag

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Extremely Large-Scale Dynamic Metasurface Antennas (XL-DMAs): Near-Field Modeling and Channel Estimation

arXiv

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arXiv 2024年

作者： Yang, Songjie Lyu, Wanting Ning, Boyu Xiu, Yue Xiong, Youzhi Chen, Hua Assi, Chadi Yuen, Chau The National Key Laboratory of Wireless Communications University of Electronic Science and Technology of China Chengdu611731 China College of Air Traffic Management Civil Aviation Flight University of China Sichuan618311 China College of Physics and Electronic Engineering Sichuan Normal University Chengdu610101 China The Faculty of Electrical Engineering and Computer Science Ningbo University Ningbo315211 China The Zhejiang Key Laboratory of Mobile Network Application Technology Ningbo315211 China Concordia University MontrealQCH3G 1M8 Canada The School of Electrical and Electronics Engineering Nanyang Technological University Singapore

Dynamic metasurface antennas (DMAs) represent a novel transceiver array architecture for extremely large-scale (XL) communications, offering the advantages of reduced power consumption and lower hardware costs compared to conventional arrays. This paper focuses on near-field channel estimation for XL-DMAs. We begin by analyzing the near-field characteristics of uniform planar arrays (UPAs) and introducing the Oblong Approx. model. This model decouples elevation-azimuth (EL-AZ) parameters for XL-DMAs, providing an effective means to characterize the near-field effect. It offers simpler mathematical expressions than the second-order Taylor expansion model, all while maintaining negligible model errors for oblong-shaped arrays. Building on the Oblong Approx. model, we propose an EL-AZ-decoupled estimation framework that involves near- and far-field parameter estimation for AZ/EL and EL/AZ directions, respectively. The former is formulated as a distributed compressive sensing problem, addressed using the proposed off-grid distributed orthogonal least squares algorithm, while the latter involves a straightforward parallelizable search. Crucially, we illustrate the viability of decoupled EL-AZ estimation for near-field UPAs, exhibiting commendable performance and linear complexity correlated with the number of metasurface elements. Moreover, we design an measurement matrix optimization method with the Lorentzian constraint on DMAs and highlight the estimation performance degradation resulting from this constraint. Copyright © 2024, The Authors. All rights reserved.

关键词： Channel estimation

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Adaptive wave-particle decomposition in UGKWP method for high-speed flow simulations

arXiv

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arXiv 2023年

作者： Wei, Yufeng Cao, Junzhe Ji, Xing Xu, Kun Department of Mathematics Hong Kong University of Science and Technology Hong Kong School of Aeronautics Northwestern Polytechnical University Shaanxi Xi’an710072 China Shaanxi Key Laboratory of Environment and Control for Flight Vehicle Xi'an Jiaotong University Xi’an China Department of Mechanical and Aerospace Engineering Hong Kong University of Science and Technology Hong Kong HKUST Shenzhen Research Institute Shenzhen518057 China

With wave-particle decomposition, a unified gas-kinetic wave-particle (UGKWP) method has been developed for the multiscale flow simulations. With the variation of cell's Knudsen number, the UGKWP method captures the transport process in all flow regimes without kinetic solver's constraint on the numerical mesh size and time step being less than the particle mean free path and collision time. In the current UGKWP method, the cell's Knudsen number, which is defined as the ratio of particle collision time to numerical time step, is used to distribute the components in the wave-particle decomposition. However, the adaptation of particle in UGKWP is mainly for the capturing of the non-equilibrium transport, and the cell's Knudsen number alone is not enough to identify the non-equilibrium state. For example, in the equilibrium flow regime with a Maxwellian distribution function, even at a large cell's Knudsen number, the flow evolution can be still modelled by the Navier-Stokes solver. More specifically, in the near space environment both the hypersonic flow around a space vehicle and the plume flow from a satellite nozzle will encounter a far field rarefied equilibrium flow in a large computational domain. In the background dilute equilibrium region, the large particle collision time and a uniform small numerical time step can result in a large local cell's Knudsen number and make UGKWP track a huge number of particles for the far field background flow. But, in this region the analytical wave representation can be legitimately used in UGKWP to capture the nearly equilibrium flow evolution. Therefore, to further improve the efficiency of UGKWP for multiscale flow simulations, an adaptive UGKWP (AUGKWP) method will be developed with the introduction of an additional local flow variable gradient-dependent Knudsen number. As a result, the wave-particle decomposition in UGKWP will be determined by both cell's and gradient's Knudsen numbers, and the use of particle in UGKWP is

关键词： Cells

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Influence of combination forms of intact sub-layer and tectonically deformed sub-layer of coal on the gas drainage performance of boreholes: a numerical study

引用

International Journal of Coal science & technology 2020年第3期7卷 571-580页

作者： Wei Zhao Kai Wang Rong Zhang Huzi Dong Zhen Lou Fenghua An Beijing Key Laboratory for Precise Mining of Intergrown Energy and Resources China University of Mining&TechnologyBeijingBeijing100083China School of Emergency Management and Safety Engineering China University of Mining&TechnologyBeijingBeijing100083China Flight Technology College Civil Aviation University of ChinaTianjin300300China State Key Laboratory Cultivation Base for Gas Geology and Gas Control(Henan Polytechnic University) Jiaozuo454003China

High concentration and large flow flux of gas drainage from underground coal seams is the precondition of reducing emission and large-scale use of ***,the layered occurrence of coal seams with tectonically deformed sub-layers and intact sub-layers makes it difficult to effectively drain gas through commonly designed *** this study,the gas drainage performance in coal seams with different combinations of tectonically deformed sub-layers and intact sub-layers was numerically *** analysis results show that the gas drainage curve changes from a single-stage line to a dual-stage curve as the permeability ratios of Zone II(kII)and Zone I(kI)increase,raising the difficulty in gas ***,a dual-system pressure decay model based on the first-order kinetic model was developed to describe the dual-stage characteristics of pressure decay curves with different permeability *** the end,the simulation results were verified with reference to in-situ drainage data from *** research results are helpful for mines,especially those with layered coal seams comprising tectonically deformed sub-layers and intact sub-layers,to choose appropriate gas drainage methods and develop the original drainage designs for achieving better gas drainage performance.

关键词： Tectonically deformed coal Pressure decay Permeability Hydraulic flushing boreholes

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Simulation and Verification of Pressure Drop in Silicon Microchannel Based on Porous Model Equivalence 21

Simulation and Verification of Pressure Drop in Silicon Micr...

引用

21st International Conference on Electronic Packaging technology, ICEPT 2020

作者： Chen, Chuan Ma, Rui Hou, Fengze Su, Meiying Li, Jun Cao, Liqiang Liang, Xiaobo Zhang, Meiju Liu, Ge Institute of Microelectronics of the Chinese Academy of Sciences Beijing China Aviation Key Laboratory of Science and Technology on Special Condition Monitoring Sensor Technology Beijing Changcheng Aeronautic Measurement and Control Technology Research Institute Beijing China

ISBN: (数字)9781728168265

ISBN: (纸本)9781728168265

Pressure drop is an important parameter of microchannel liquid cold plate. In this article, the pressure drop of the staggered strip fin microchannel was simulated based on porous model equivalence by FLUENT software. Periodic cell pressure drop was simulated to equal to that of the entire liquid cold plate. The parameters of the porous model were calculated by the relationship between pressure drop and flow rate. A model including manifold and liquid cold plate was established, in which the liquid cold plate was equivalent by the porous model, and the total pressure drop of the cooling module was acquired by simulation. Finally, a test system was built, and the simulation method based on the porous model equivalence was proved to be simple, efficient and accurate through the comparison of simulation and test values. © 2020 IEEE.

关键词： Pressure drop

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