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Performance of the Multilayer Film for Infrared Stealth based on VO_(2) Thermochromism

Journal of Thermal Science 2024年第4期33卷 1312-1324页

作者： LI Yaru WANG fuqiang ZHANG Aoyu fu Zhichang SU Ronghua GAO Tengfei WANG Zhen guo Jicheng ORDOS Institute of Technology Ordos017000China School of Energy Science and Engineering Harbin Institute of TechnologyHarbin150001China School of New Energy Harbin Institute of Technology at WeihaiWeihai264209China Defense Engineering Institute AMSPLABeijing100850China

With the development of detection and identification technology,infrared stealth is of great value to realize anti-reconnaissance detection of military *** present,infrared stealth materials generally have deficiency,such as complex structure,inconvenient radiation regulation and cumbersome preparation steps,which greatly limit the practical application of infrared stealth *** view of the above deficiency of infrared stealth materials,we proposed a kind of multilayer film for infrared stealth using VO2thermochromism based on the temperature response mechanism of tuna to adjust its color,and through the intelligent reversible radiation regulation mechanism to meet the infrared stealth requirements of tanks in different actual *** results show that when the temperature increases from 300 K to 373 K,the peak emissivity of the film decreases from 94%to 20%in the 8-14μm band after structural optimization,which can realize the infrared stealth of the high temperature target in the 8-14μm *** average emissivity of the multilayer film for infrared stealth at3-5μm and 8-14μm band can be reduced to 34%and 27%at 373 K,and the peak emissivity at 5-8μm band can reach 65%,realizing dual-band infrared stealth in the 3-5μm and 8-14μm bands and heat dissipation in the 5-8μm *** multilayer film for infrared stealth based on VO2thermochromism designed by the authors can meet the characteristics of simple film structure,convenient radiation regulation and simple preparation.

关键词： vanadium dioxide multilayer film infrared stealth thermal management

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Cryptic diversity and rampant hybridization in annual gentians on the Qinghai-Tibet Plateau revealed by population genomic analysis

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Plant Diversity 2024年第2期46卷 194-205页

作者： Peng-Cheng fu Qiao-Qiao guo Di Chang Qing-Bo Gao Shan-Shan Sun School of Life Science Luoyang Normal UniversityLuoyang 471934PR China Key Laboratory of Adaptation and Evolution of Plateau Biota Northwest Institute of Plateau BiologyChinese Academy of SciencesXining 810001PR China

Understanding the evolutionary and ecological processes involved in population differentiation and speciation provides critical insights into biodiversity formation. In this study, we employed 29,865 single nucleotide polymorphisms(SNPs) and complete plastomes to examine genomic divergence and hybridization in Gentiana aristata, which is endemic to the Qinghai-Tibet Plateau(QTP) region. Genetic clustering revealed that G. aristata is characterized by geographic genetic structures with five clusters(West, East, Central, South and North). The West cluster has a specific morphological character(i.e., blue corolla) and higher values of FSTcompared to the remaining clusters, likely the result of the geological barrier formed by the Yangtze River. The West cluster diverged from the other clusters in the Early Pliocene;these remaining clusters diverged from one another in the Early Quaternary. Phylogenetic reconstructions based on SNPs and plastid data revealed substantial cyto-nuclear conflicts. Genetic clustering and D-statistics demonstrated rampant hybridization between the Central and North clusters,along the Bayankala Mountains, which form the geological barrier between the Central and North clusters. Species distribution modeling demonstrated the range of G. aristata expanded since the Last Interglacial period. Our findings provide genetic and morphological evidence of cryptic diversity in G. aristata, and identified rampant hybridization between genetic clusters along a geological *** findings suggest that geological barriers and climatic fluctuations have an important role in triggering diversification as well as hybridization, indicating that cryptic diversity and hybridization are essential factors in biodiversity formation within the QTP region.

关键词： Gentiana aristata Hybrid zone Qinghai-Tibet Plateau Plastome Nuclear SNPs

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Ammonia storage and slip under steady and transient state in close-coupled SCR

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Journal of Environmental Sciences 2024年第4期138卷 470-481页

作者： Shiyu Liu Zhaohuan Zhang Zexian guo Boyuan Wang Buyu Wang Xiao ma Shijin Shuai State Key Laboratory of Automotive Safety and Energy Tsinghua UniversityBeijing 100084China Institute for Aero Engine Tsinghua UniversityBeijing 100084China

The close-coupled selective catalytic reduction(cc-SCR)catalyst is an effective technology to reduce tailpipe NOx emission during cold *** paper investigated the optimal ammonia storage under steady and transient state in the *** study showed that a trade-off between NOx conversion efficiency and ammonia slip is observed on the pareto solutions under steady state,and the optimal ammonia storage is calculated with ammonia slip less than 10μL/L based on the ChinaⅥemission *** rapid temperature increase will lead to severe ammonia slip in the transient test cycle.A simplified 0-D calculation method on ammonia slip under transient state is proposed based on kinetic model of ammonia adsorption and *** addition,the effect of ammonia storage,catalyst temperature and temperature increasing rate on ammonia slip are *** optimal ammonia storage is calculated with maximum ammonia slip less than 100μL/L according to the oxidation efficiency of ammonia slip catalyst(ASC)downstream *** was found that the optimal ammonia storage under transient state is much lower than that under steady state in cc-SCR at lower temperature,and a phase diagram is established to analyze the influence of temperature and temperature increasing rate on optimal ammonia storage.

关键词： Close-coupled SCR Ammonia storage and slip Steady and transient state Generic algorithm

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Tribological properties of PTFE-based fabric composites at cryogenic temperature

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Friction 2024年第2期12卷 245-257页

作者： Mingkun XU Zidan WANG Lihe guo Liming TAO Tianbao ma Tingmei WANG Qihua WANG Key Laboratory of Science and Technology on Wear and Protection of materials Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China Center of materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

Fabric composites are widely employed in self-lubricating bearing liners as solid lubrication *** the tribological behaviors of fabric composites have been extensively studied,the cryogenic tribological properties and mechanisms have been scarcely reported and are largely unclear to instruct material design for aerospace and other high-tech ***,the tribological properties of polytetrafluoroethylene(PTFE)-based hybrid-fabric composites were investigated at cryogenic and ambient temperatures in the form of pin-on-disk friction under heavy *** results suggest that the friction coefficients of the hybrid-fabric composites obviously increase with a decrease in wear when the temperature drops from 25 to−150°***,thermoplastic polyetherimide(PEI),as an adhesive for fabric composites,has better cryogenic lubrication performance than thermosetting phenol formaldehyde(PF)resin,which can be attributed to the flexible chemical structure of *** excellent lubrication performance of hybrid-fabric composites is attributed to the transfer film formed by PTFE fibers on the surface of fabrics.

关键词： cryogenic temperatures fabric composites friction and wear transfer film

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Alcohol solvent effect on the self-assembly behaviors of lignin oligomers

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Green Energy & Environment 2024年第4期9卷 597-603页

作者： Ya ma Zhicheng Jiang Yafei Luo Xingjie guo Xudong Liu Yiping Luo Bi Shi College of Biomass Science and Engineering Sichuan UniversityChengdu610065China National Engineering Research Center of Clean Technology in Leather Industry Sichuan UniversityChengdu610065China College of Pharmacy(International Academy of Targeted Therapeutics and Innovation) Chongqing University of Arts and SciencesChongqing402160China State Key Laboratory of Utilization of Woody Oil Resource Hunan Academy of ForestryChangsha410004China CAS Key Laboratory of Environmental and Applied Microbiology Environmental Microbiology Key Laboratory of Sichuan ProvinceChengdu Institute of BiologyChinese Academy of SciencesChengdu610041China

The interactions between lignin oligomers and solvents determine the behaviors of lignin oligomers self-assembling into uniform lignin nanoparticles(LNPs).Herein,several alcohol solvents,which readily interact with the lignin oligomers,were adopted to study their effects during solvent shifting process for LNPs’*** lignin oligomers with widely distributed molecular weight and abundant guaiacyl units were extracted from wood waste(mainly consists of pine wood),exerting outstanding self-assembly *** and spherical LNPs were generated in H_(2)O-n-propanol cosolvent,whereas irregular LNPs were obtained in H_(2)O-methanol *** unsatisfactory self-assembly performance of the lignin oligomers in H_(2)O-methanol cosolvent could be attributed to two *** one hand,for the initial dissolution state,the distinguishing Hansen solubility parameter and polarity between methanol solvent and lignin oligomers resulted in the poor dispersion of the lignin *** the other hand,strong hydrogen bonds between methanol solvent and lignin oligomers during solvent shifting process,hindered the interactions among the lignin oligomers for self-assembly.

关键词： Lignin oligomers Alcohol solvent Self-assembly LNPs Solvent effects

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Experimental and computational investigation on flow characteristics of rotating cavities with high inlet pre-swirl axial throughflow

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Chinese Journal of Aeronautics 2024年第4期37卷 276-293页

作者： Sipeng WANG Xiang LUO Linji guo Zeyu WU Yang BAI Zongchao LI Lichun ma School of Energy and Power Engineering Beihang UniversityBeijing 100191China Research Institude of Aero-Enigine Beihang UniversityBeijing 100191China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang UniversityBeijing 100191China Shenyang Aeroengine Research Institute Aero Engine Corporation of ChinaShenyang 110015China

As an integral part of the internal air system of aero-engines,the axial throughflow of the cooling air can interact with the cavity flow between the rotating compressor disks,forming a threedimensional,unsteady,and unstable flow *** flow characteristics in an engine-like rotating multi-stage cavity with throughflow were investigated using particle image velocimetry,flow visualization technology and three-dimensional unsteady Reynolds-Averaged Navier-Stokes (RANS)*** focus of current research was to understand the distribution of the mean swirl ratio and its variation with a wide range of non-dimensional parameters in the co-rotating cavity with high inlet pre-swirl axial *** maximum axial Reynolds number and rotational Reynolds numbers could reach 4.41×10^(4)and 1.24×10^(6),*** velocity measurement results indicate that the mean swirl ratio is greater than 1 and decreases with an increase in the radial *** flow structure is dominated by the Rossby number,and two different flow patterns (flow penetration and flow stratification) are identified and confirmed by flow visualization *** the absence of buoyancy,the flow penetration caused by the precession of the throughflow makes it easier for the throughflow to reach a high radius *** consistency of results between measurements and numerical calculations is *** study provides a theoretical basis and data support for toroidal vortex breakdown,which is of practical significance for the design of high-pressure compressor cavities.

关键词： Compressor Axial throughflow Rotating cavity flow Particle image velocimetry Unsteady RANS Flow pattern

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Comparison of nonlinear modeling methods for the composite rubber clamp

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Applied mathematics and Mechanics(English Edition) 2024年第5期45卷 763-778页

作者： Yiming CAO Hui ma Xumin guo Bingfeng ZHAO Hui LI Xin WANG Bing WANG School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China Key Laboratory of Vibration and Control of Aero-Propulsion Systems of Ministry of Education of China Northeastern UniversityShenyang 110819China AVIC Shenyang Engine Design Institute Shenyang 110013China Dalian Mengyu machinery Co. Ltd.Dalian 116317Liaoning ProvinceChina

The cubic stiffness force model(CSFM)and Bouc-Wen model(BWM)are introduced and compared *** unknown coefficients of the nonlinear models are identified by the genetic algorithm combined with *** fitting the identified nonlinear coefficients under different excitation amplitudes,the nonlinear vibration responses of the system are *** results show that the accuracy of the BWM is higher than that of the CSFM,especially in the non-resonant ***,the optimization time of the BWM is longer than that of the CSFM.

关键词： pipeline system nonlinear clamp model composite rubber clamp amplitude-dependent characteristic vibration response experiment

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Dynamically updated digital twin for prognostics and health management:Application in permanent magnet synchronous motor

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Chinese Journal of Aeronautics 2024年第6期37卷 244-261页

作者： Haoyu guo Shaoping WANG Jian SHI Tengfei ma Giorgio GUGLIERI Rujun JIA Fausto LIZZIO School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China Tianmushan Laboratory Hangzhou 310023China Department of Mechanical and Aerospace Engineering Polytechnic University of TurinTurin 10129Italy Beihang Ningbo Research Institute Ningbo 315800China

Current research on Digital Twin(DT)based Prognostics and Health management(PHM)focuses on establishment of DT through integration of real-time data from various sources to facilitate comprehensive product monitoring and health ***,there still exist gaps in the seamless integration of DT and PHM,as well as in the development of DT multi-field coupling modeling and its dynamic update *** the product experiences long-period degradation under load spectrum,it is challenging to describe the dynamic evolution of the health status and degradation progression *** addition,DT update algorithms are difficult to be integrated simultaneously by current *** paper proposes an innovative dual loop DT based PHM framework,in which the first loop establishes the basic dynamic DT with multi-filed coupling,and the second loop implements the PHM and the abnormal detection to provide the interaction between the dual loops through updating *** proposed method pays attention to the internal state changes with degradation and interactive mapping with dynamic parameter ***,the Independence Principle for the abnormal detection is proposed to refine the theory of *** at the first loop focus on accurate modeling of multi-field coupling,while the events at the second loop focus on real-time occurrence of anomalies and the product degradation *** interaction and collaboration between different loop models are also ***,the Permanent magnet Synchronous Motor(PMSM)is used to verify the proposed *** results show that the modeling method proposed can accurately track the lifecycle performance changes of the entity and carry out remaining life prediction and health management effectively.

关键词： Digital Twin(DT) Dynamic Update Independence Principle Multi-field Coupling Permanent magnet Synchronous Motor(PMSM) Prognostics and Health management(PHM)

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YOLO-Drone:A Scale-Aware Detector for Drone Vision

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Chinese Journal of Electronics 2024年第4期33卷 1034-1045页

作者： Yutong LI Miao ma Shichang LIU Chao YAO Longjiang guo School of Computer Science Shaanxi Normal University Key Laboratory of Modern Teaching Technology Ministry of Education College of Computer Science Sichuan University

Object detection is an important task in drone vision. Since the number of objects and their scales always vary greatly in the drone-captured video, small object-oriented feature becomes the bottleneck of model performance, and most existing object detectors tend to underperform in drone-vision scenes. To solve these problems, we propose a novel detector named YOLO-Drone. In the proposed detector, the backbone of YOLO is firstly replaced with ConvNeXt, which is the state-of-the-art one to extract more discriminative features. Then, a novel scale-aware attention(SAA) module is designed in detection head to solve the large disparity scale problem. A scale-sensitive loss(SSL) is also introduced to put more emphasis on object scale to enhance the discriminative ability of the proposed detector. Experimental results on the latest VisDrone 2022 test-challenge dataset(detection track) show that our detector can achieve average precision(AP) of 39.43%, which is tied with the previous state-of-the-art, meanwhile,reducing 39.8% of the computational cost.

关键词： YOLO Costs Object oriented modeling Computational modeling Detectors Feature extraction Data models

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Catalytic Reaction Kinetics of Propylene Dimerization to 4-Methyl-1-Pentene Using Cu-K/K_(2)CO_(3) Solid Base Catalyst

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China Petroleum Processing & Petrochemical Technology 2024年第1期26卷 78-87页

作者： Jin Haibo Chai Jing Yang Suohe He Guangxiang ma Lei guo Xiaoyan College of New materials and Chemical Engineering Beijing Institute of Petrochemical Technology/Beijing Key Laboratory of Fuel Cleaning and Efficient Catalytic Emission Reduction TechnologyBeijing102617China

The catalysis technology of propylene dimerization to form 4-methyl-1-pentene(4MP1)using a Cu-K/K_(2)CO_(3) solid base catalyst is a well-known heterogeneous catalytic *** this study,the intrinsic kinetics of propylene dimerization were studied in a fixed-bed continuous *** and external diffusion during the dimerization reaction experiments were eliminated by adjusting the flow rate of the carrier gas and the particle size of the catalyst ***,the concentration changes of each substance at the outlet of the catalyst bed under different residence times were ***,the suitable reaction kinetics equations was derived using the Langmuir Hinshelwood-Hougen-Watson kinetic ***,the activation energy for each reaction involved in the dimerization reaction was *** activation energies of 4MP1,branched by-products,and 1-hexene were 115.0,150.8,and 177.4 kJ/mol,*** effect of process conditions on propylene dimerization with solid base catalysts was studied through kinetic model *** comparing the theoretical values obtained from the simulation with the experimental results,the applicability and accuracy of the kinetic model were verified.

关键词： propylene dimerization 4-methyl-1-pentene intrinsic kinetics surface reaction

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