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Autonomous maneuver decision-making for a UCAV in short-range aerial combat based on an MS-DDQN algorithm

Defence Technology（防务技术） 2022年第9期18卷 1697-1714页

作者： yong-feng li Jing-ping Shi Wei Jiang Wei-guo Zhang yong-xi Lyu School of Automation Northwestern Polytechnical UniversityXi'an 710129China Shaanxi Province Key Laboratory of Flight Control and Simulation Technology Xi'an 710129China

To solve the problem of realizing autonomous aerial combat decision-making for unmanned combat aerial vehicles(UCAVs) rapidly and accurately in an uncertain environment, this paper proposes a decision-making method based on an improved deep reinforcement learning(DRL) algorithm: the multistep double deep Q-network(MS-DDQN) algorithm. First, a six-degree-of-freedom UCAV model based on an aircraft control system is established on a simulation platform, and the situation assessment functions of the UCAV and its target are established by considering their angles, altitudes, environments, missile attack performances, and UCAV performance. By controlling the flight path angle, roll angle, and flight velocity, 27 common basic actions are designed. On this basis, aiming to overcome the defects of traditional DRL in terms of training speed and convergence speed, the improved MS-DDQN method is introduced to incorporate the final return value into the previous steps. Finally, the pre-training learning model is used as the starting point for the second learning model to simulate the UCAV aerial combat decision-making process based on the basic training method, which helps to shorten the training time and improve the learning efficiency. The improved DRL algorithm significantly accelerates the training speed and estimates the target value more accurately during training, and it can be applied to aerial combat decision-making.

关键词： Unmanned combat aerial vehicle Aerial combat decision Multi-step double deep Q-network Six-degree-of-freedom Aerial combat maneuver library

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Achievement of high performance of sintered R-Fe-B magnets based on misch metal doped with PrNd nanoparticles

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Rare Metals 2018年第3期37卷 237-242页

作者： Qiang Ma Jian-Teng Zhu Xue-feng Zhang Zeng-Ru Zhao Yan-li liu Gao-feng Wang yong-feng li Zhu-Bai li Key Laboratory of Integrated Expoitation of Bayan Obo MultiMetal Resources Inner Mongolia University of Science and Technology College of Science Inner Mongolia University of Science and Technology

The magnetic properties and microstructure of sintered R-Fe-B（R, rare earth） magnets with nominal composition of（（PrNd）（1-x）MMx）（30）Fe（bal）B1（x = 0, 0.***.0.2,0.3, 0.4, 0.5 and 0.7; MM, misch metal） prepared using dual-alloy method were investigated. For x = 0.3, the maximum energy product（（BH）（max）） of the sintered magnet is higher than 318.4 kJ·m^-3,but intrinsic coercivity（H（cj）） is lower than 351.8 kA·m^-1. The La and Ce contents are obviously different in some matrix-phase grains, which proves that the multi-hard magnetic phases（La, Ce-rich and La, Ce-lean） exist in the magnets. The coercivity is improved by the method of doping PrNd nanoparticles without sacrificing other magnetic properties. An enhancement in coercivity from 517.2 to 872.9 kA·m^-1 is achieved by doping 5 wt% PrNd nanoparticles. Meanwhile, it could exhibit better magnetic properties（remanence Br = 1.332 *** coercivity H（cj）= 872.9 kA·m^-1 maximum energy product（BH）（max）=318.6 kJ·m^-3） and make the distribution of the intergranular phase become more homogeneous.

关键词： Permanent magnetic materials Nanoparticles Misch metal Dual-alloy Coercivity

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Shared aperture metasurface antenna for electromagnetic vortices generation with different topological charges

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Chinese Physics B 2021年第8期30卷 337-344页

作者： He Wang yong-feng li Shao-Bo Qu Department of Basic Sciences Air Force Engineering UniversityXi'an 710051China

Vortex beams carrying orbital angular momentum(OAM)have aroused great interest of both scientific and engineering ***,generating OAM with different topological charges in a shared aperture is regarded as a potential route to expanding the communication capacity,which yet is an academic challenging *** this work,a paradigm of designing metasurface-based shared aperture antenna for generating polarization-dependent vortex beams with distinct topological charges is *** unit cells that can tailor different resonance phase profiles in two orthogonal orientations are used to assemble a metasurface *** a proof-of-concept,a planar reflector antenna is designed with two Vivaldi sources,which can generate x-and y-polarized vortex beams with topological charges of l=-1 and l=-2,*** the simulation results and the measurement results are in good agreement,which demonstrates the feasibility of our ***,this work provides a new route to achieving vortex beams carrying different topological charges in the same frequency band,which may have potential applications in communication systems.

关键词： metasurface electromagnetic vortex antenna orbital angular momentum

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Transient Properties of a Bistable System with Delay Time Driven by Non-Gaussian and Gaussian Noises:Mean First-Passage Time

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Communications in Theoretical Physics 2008年第9期50卷 669-673页

作者： li Dong-Xi XU Wei GUO yong-feng li Gao-Jie Department of Applied Mathematics Northwestern Polytechnical University Xi＇an 710072 China

The mean first-passage time of a bistable system with time-delayed feedback driven by multiplicative non-Gaussian noise and additive Gaussian white noise is investigated. Firstly, the non-Markov process is reduced to the Markov process through a path-integral approach; Secondly, the approximate Fokker-Planck equation is obtained by applying the unified coloured noise approximation, the small time delay approximation and the Novikov Theorem. The functional analysis and simplification are employed to obtain the approximate expressions of MFPT. The effects of non-Gaussian parameter （measures deviation from Gaussian character） r, the delay time τ, the noise correlation time to, the intensities D and a of noise on the MFPT are discussed. It is found that the escape time could be reduced by increasing the delay time τ, the noise correlation time τ0, or by reducing the intensities D and α. As far as we know, this is the first time to consider the effect of delay time on the mean first-passage time in the stochastic dynamical system.

关键词： mean first-passage time delay time non-Gaussian noise Gaussian noise bistable system

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Magnetic properties of melt-spun MM-Fe-B ribbons with different wheel speeds and mischmetal contents

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Rare Metals 2017年第12期36卷 992-996页

作者： Xue-feng Zhang Wen-Kai Zhang yong-feng li Yan-li liu Zhu-Bai li Qiang Ma Meng-Fei Shi Fei liu Key Laboratory of Integrated Exploitation of Bayan Obo Multi-Metal Resources Inner Mongolia University of Science andTechnology Baotou 014010 China Schools of Mathematics Physics and Biological EngineeringInner Mongolia University of Science and TechnologyBaotou 014010 China

In this study, the effect of wheel speed and mischmetal（MM） content on the magnetic properties of MMFeB ribbons was investigated. The samples were prepared via direct solidification technique. The nominal composition of the alloy ingots is MM;Fe;B;with x varying from 9 to 15 in steps of 2. Experimental results show the overall magnetic properties of the *** of the results shows that the magnetic properties first improve and then degrade with the wheel speed and MM content increasing. Increase in MM content leads to better formation of crystal texture in the ribbons, indicating that the a-Fe phase might undermine the formation of crystal texture. Magnetic properties results show that the coercivity of the ribbons rises with an appropriate increase in both MM content and wheel speed during melt-spun process. The strongest magnetic properties of the ribbons(remanence of M;= 0.72 T, intrinsic coercivity of H;= 352.58 kA·m;, and maximum energy product of（BH）;=72.14 kJ·m;) are obtained for compositions where x = 13 and a wheel speed of v = 20 m·s;.

关键词： Mischmetal MMFeB Magnetic properties Melt spun

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Time Dependence of Entropy Flux and Entropy Production of a Dissipative Dynamical System Driven by Non-Gaussian Noise

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Communications in Theoretical Physics 2008年第6期49卷 1561-1566页

作者： GUO yong-feng XU Wei li Dong-Xi XIE Wen-Xian Department of Applied Mathematics Northwestern Polytechnical University Xi＇an 710072 China

A stochastic dissipative dynamical system driven by non-Gaussian noise is investigated. A general approximate Fokker-Planck equation of the system is derived through a path-integral approach. Based on the definition of Shannon＇s information entropy, the exact time dependence of entropy flux and entropy production of the system is calculated both in the absence and in the presence of non-equilibrium constraint. The present calculation can be used to interpret the interplay of the dissipative constant and non-Gaussian noise on the entropy flux and entropy production.

关键词： information entropy entropy flux and entropy production non-Gaussian noise Fokker-Planck equation

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Preparation and Characterization of Amorphous W–B–C Alloy and Solid Solutions of C in Tungsten Borides

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Acta Metallurgica Sinica(English Letters) 2018年第4期31卷 380-388页

作者： Hao Sun Suo-Zhu Bai Dan-Dan Yao Bin Yao Zhan-Hui Ding yong-feng li State Key Lab of Superhard Materials and College of Physics Jilin UniversityChangchun 130023China Key Laboratory of Physics and Technology for Advanced Batteries(Ministry of Education) College of PhysicsJilinUniversityChangchun 130012China Chemistry and Chemical Engineering College Inner Mongolia University for the NationalitiesTongliao 028000China liaoning Academy of Safety Science Shenyang 110004China

Mixtures of W and B13C2 powders were mechanically milled and subsequently annealed at 900-1200℃.It is found that amorphous W-B-C alloy formed as the mixtures were milled for 20.80 *** annealing the 80 h-milled mixtures at 900-950℃,solid solutions of C and/or B in tungsten[W（B,C）],C in tungsten boride[W2B（C）or WB（C）]formed by the crystallization of amorphous *** formation temperature of W2B（C）and WB（C）is lower than that of W2B and WB reported *** the 80 h-milled mixtures were annealed at 1200℃,W reacted with amorphous W-B-C completely to form WB and W2B5 or W2B5 instead of the solid solutions of C in tungsten borides,which is determined by the mole ratio of W to *** formation mechanisms of the W2B（C）and WB（C）solid solutions as well as phase transition rules of the mixtures at annealing temperature and mole ratio were also investigated using first-principle calculation.

关键词： Ball milling Annealing Tungsten borides Amorphous alloy

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Ultra-thin and light-weight spoof surface plasmon polariton coupler achieved by broadside coupled split ring resonators

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Chinese Physics B 2018年第10期27卷 175-180页

作者： Ya Fan Jia-Fu Wang Hua Ma yong-feng li Ming-De feng Shao-Bo Qu Department of Basic Sciences Air Force Engineering UniversityXi＇an 710051China

Low profile and light weight are very important for practical applications of a spoof surface plasmon polariton（SSPP）coupler, especially at low frequencies. In this paper, we propose and design an ultra-thin, light-weight SSPP coupler based on broadside coupled split ring resonators（BC-SRRs）. The size of BC-SRR can be far less than λ/100 and can extremely well control the reflective phases within a subwavelength thickness. Due to the broadside capacitive coupling, the electrical size of BC-SRR is dramatically reduced to guarantee the ultra-thin thickness of the SSPP coupler. The weight of the SSPP coupler is reduced by a low occupation ratio of BC-SRR in the unit cell volume. As an example, a C-band SSPP coupler composed of phase gradient BC-SRRs is designed, fabricated, and measured. Due to the ultra-small size and low occupation ratio of BC-SRRs, the thickness of the coupler is λ/12 and the surface density is only 0.98 kg/m^2. Both simulation and experiment results verify that the coupler can achieve high-efficiency SPP coupling at 5.27 GHz under normal incidence.

关键词： ultra-thin light-weight poof surface plasmon polariton broadside coupling

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Principal Chemical Properties of Artificial Soil Composed of Fly Ash and Furfural Residue

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Pedosphere 2006年第5期16卷 668-672页

作者： feng yong-Jun li Fen WANG Xiao-ling liU Xi-Min ZHANG Lei-Na College of Resources and Environment Shandong Agricultural University Tai＇an 271018 （China） Institute of Geographical Sciences and Nature Resources Research Beijing 100101 （China）

To solve soil shortage in reclaiming subsided land of coal mines, the principal chemical properties of artificial soil formed by mixing organic furfural residue and inorganic fly ash were examined. The results indicated that the artificial soil was suitable for agriculture use after irrigation and desalination, the available nutrients in the artificial soil could satisfy the growth demand of plants, and the pH tended to the neutrality.

关键词： artificial soil chemical properties fly ash furfural residue

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Chinese Sunspot Drawings and Their Digitization—(Ⅶ) Sunspot Penumbra to Umbra Area Ratio Using the Hand-Drawing Records from Yunnan Observatories

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Research in Astronomy and Astrophysics 2022年第9期22卷 132-139页

作者： Jia-Wei Hou Shu-Guang Zeng Sheng Zheng Xiao-Yu Luo lin-Hua Deng Yang-Yang li Yan-Qing Chen Gang-Hua lin yong-li feng Jin-Ping Tao Center for Astronomy and Space Sciences China Three Gorges UniversityYichang 443002China College of Science China Three Gorges UniversityYichang 43002China Yunnan Observatories Chinese Academy of SciencesKunming.650216China National Astronomical Observatories Chinese Academy of SciencesKunming650216China

The ratio of penumbral to umbra area of sunspots plays a crucial role in the solar physics fields, especially for understanding the origin and evolution of the solar activity cycle. By analyzing the recently digitized sunspot drawings observed from Yunnan Observatories(1957–2021), we investigate the long-term variation of the penumbral to umbra area ratio of sunspots. An automatic extraction method, based on the maximum between-class variance and the morphological discrimination, is used to accurately extract penumbra and umbra and to calculate the ratio over six solar cycles(cycle 19–24). The expected value of the ratio of penumbra to umbra area is found to be 6.63 ± 0.98, and it does not exhibit any systematic variation with sunspot latitudes and phases. The average ratio fluctuates from 5 to 7.5 per year and the overall trend has decreased after 1999 compared to the previous *** ratio of sunspot penumbra to umbra area satisfies the log-normal distribution, implying that its variation is related to the evolution of the photospheric magnetic field. Our results are consistent with previous works.

关键词： Sun:sunspots Sun:photosphere Sun:activity techniques:image processing

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