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Plasma Science and Technology 2020年第10期22卷 95-99页

作者： Junxia ran Haiyun LUO Caixia LI Xiaowei LI Xuechen LI College of Physics Science and Technology Hebei UniversityBaoding 071002People's Republic of China Hebei Key Lab of Optic-Electronic Information and Materials Baoding 071002People's Republic of China Institute of Life Science and Green Development Hebei UniversityBaoding 071002People's Republic of China State Key Laboratory of Power System Department of Electrical EngineeringTsinghua UniversityBeijing 100084People's Republic of China

Fast photography and optical emission spectroscopy are implemented in a 5 mm neon gap dielectric barrier discharge(DBD) at atmospheric pressure with quartz glass used as the dielectric layer. Results show that it starts with a Townsend discharge and ends at a sub-normal glow discharge in neon DBD. Based on the Townsend discharge, the first ionization coefficient of neon is measured. The measurements are consistent with those at low pressure. Optical emission spectroscopy indicates that the spectra are mainly composed of atomic lines of neon, molecular bands and molecular ion bands originating from inevitable gas impurities(mainly nitrogen).Moreover, spectral lines emitted from atomic neon corresponding to the transitions(2p^5 3p→2p^5 3s) are predominant. Although the second positive system of N_2(C^3Π_u→B^3Π_g) is observed, their intensities are too weak compared with neon's spectrum. The molecular nitrogen ion line of 391.4 nm is observed. It reveals that Penning ionization between high energy neon excited states and the inevitable gas impurities plays an important role in the value of the αcoefficient.

关键词： gas discharge first Townsend's ionization coefficient Townsend discharge spectral diagnosis dielectric barrier discharge

An improved yield criterion characterizing the anisotropic and tension-compression asymmetric behavior of magnesium alloy

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Journal of Magnesium and Alloys 2022年第2期10卷 612-628页

作者： Zhigang Li Haifeng Yang Jianguang liu Fu liu School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing100044PR China Automotive Research Institute of Beijing Automotive Co. Ltd.Beijing 101300China Beijing Key Laboratory of Civil Aircraft Structures and Composite Materials COMAC Beijing Aircraft Technology Research InstituteBeijing102211PR China Shanghai Aircraft Design and Research Institute Shanghai 201210PR China

A novel yield criterion based on CPB06 considering anisotropic and tension-compression asymmetric behaviors of magnesium alloys was derived and proposed(called M_CPB06).This yield criterion can simultaneously predict the yield stresses and the Lankford ratios at different angles(if any)under uniaxial tension,compression,equal-biaxial and equal-compression ***,in order to further describe the anisotropic strain-hardening characteristics of magnesium alloy,the proposed M_CPB06 criterion was further evolved to the M_CPB06ev model by expressing the parameters of the M_CPB06 model as functions of the plastic *** the model was developed,the stresses and Lankford ratios of AZ31B and ZK61M magnesium alloys at different angles under tensile,compressive and through-thickness compressive conditions were used to calibrate the M_CPB06/M_CPB06ev and the existing CPB06ex2 *** results reveal that compared with the CPB06ex2 yield criterion with equal quantity of coefficients,the M_CPB06 criterion exhibits certain advancement,and meanwhile the M_CPB06ev model can relatively accurately predict the change of the yield locus with increase of the plastic ***,the M_CPB06ev model was developed through UMAT in *** element simulations using the subroutine were conducted on the specimens of different angles to the rolling direction under tension and *** results were highly consistent with the experimental results,demonstrating a good reliability and accuracy of the developed subroutine.

关键词： Magnesium alloy Anisotropy Tension-compression asymmetry Improved yield criterion UMAT

Iterative Signal Detection Based Soft Interference Cancellation for Satellite-Terrestrial Downlink NOMA Systems

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China Communications 2024年第8期21卷 249-263页

作者： Sun Meng Zhang Qi Yao Haipeng Gao ran Xin Xiangjun Tian Feng Feng Weiying Chen Dong School of Electronic Engineering Beijing University of Posts and Telecommunications(BUPT)Beijing 100876China Beijing Key Laboratory of Space-Ground Interconnection and Convergence State Key Laboratory of Information Photonics and Optical CommunicationsSchool of Electronic EngineeringBeijing University of Posts and Telecommunications(BUPT)Beijing 100876China School of Information and Communication Engineering Beijing University of Posts and Telecommunications(BUPT)Beijing 100876China Beijing Institute of Technology Beijing 100081China Beihang University Beijing 100191China China Academy of Space Technology(CAST) Beijing 100094China

To improve the bit error rate(BER)performance of multi-user signal detection in satelliteterrestrial downlink non-orthogonal multiple access(NOMA)systems,an iterative signal detection algorithm based on soft interference cancellation with optimal power allocation is *** that power allocation has a significant impact on BER performance,the optimal power allocation is obtained by minimizing the average BER of NOMA *** to the allocated powers,successive interference cancellation(SIC)between NOMA users is performed in descending power *** each user,an iterative soft interference cancellation is performed,and soft symbol probabilities are calculated for soft *** improve detection accuracy and without increasing the complexity,the aforementioned algorithm is optimized by adding minimum mean square error(MMSE)signal estimation before detection,and in each iteration soft symbol probabilities are utilized for soft-decision of the current user and also for the update of soft interference of the previous *** results illustrate that the optimized algorithm ***-IDBSIC significantly outperforms joint multi-user detection and SIC detection by 7.57dB and 8.03dB in terms of BER performance.

关键词： non-orthogonal multiple access(NOMA) resource allocation satellite-terrestrial communication signal detection soft interference cancellation

Pd（0）-Catalyzed Tandem One-Pot Reaction of Biphenyl Ketones/Aldehydes to the Corresponding Di-substituted Aryl Olefins

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Chinese Journal of Chemistry 2017年第7期35卷 1141-1148页

作者： Yang liu Ping liu Yan liu Yu Wei School of Chemistry and Chemical Engineering the Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan Shihezi University Shihezi Xinjiang 832003 China

Synthesis of di-substituted aryl olefins via a Pd（0）-catalyzed cross-coupling reaction of biphenyl ketones/alde- hydes, tosylhydrazide, and aryl bromides （or benzyl halides） was developed. This methodology was achieved by one-pot two-step reactions involving the preparation of N-tosylhydrazones by reacting tosylhydrazide with biphenyl ketones/aldehydes, followed by coupling with aryl bromides （or benzyl halides） in the presence of Pd（PPh3）4 and lithium t-butoxide to produce various di-substituted aryl olefins in moderate to good yields.

关键词： one-pot reaction biphenyl ketone N-tosylhydrazones di-substituted olefins palladium catalyzed

Fault-tolerance wide voltage conversion gain DC/DC converter for more electric aircraft

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Chinese Journal of Aeronautics 2023年第7期36卷 420-429页

作者： Binxin ZHU Jiaxin liu Yu liu Kaihong WANG College of Electrical Engineering and New Energy(Hubei Provincial Research Center on Microgrid Engineering Technology) China Three Gorges UniversityYichang 443002China

In this paper,a fault-tolerance wide voltage conversion gain DC/DC converter for More Electric Aircraft(MEA)is *** proposed converter consists of a basic Cuk converter module and n expandable *** adjusting the operation state of the expandable units,the voltage conversion gain of the proposed converter could be regulated,which makes it available for wide voltage conversion ***,since mutual redundancy can be realized between the basic Cuk converter module and the expandable units,the converter can continuously work when an unpredictable fault occurs to the fault-tolerant parts of the proposed converter,which reflects the fault tolerance of the converter and significantly improves the reliability of the ***,the advantages of small input current ripple,automatic current sharing and low voltage stress are also integrated in this *** working principle and features of the proposed converter are mainly introduced,and an experimental prototype with 800 W output power has been manufactured to verify the practicability and availability of the proposed converter.

关键词： Cuk converter Fault tolerance High reliability More Electric Aircraft(MEA) Wide voltage conversion gain

Enhanced strength and ductility in Al-Zn-Mg-Cu alloys fabricated by laser powder bed fusion using a synergistic grain-refining strategy

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Journal of Materials Science & Technology 2022年第29期124卷 41-52页

作者： Xiaohui liu Yunzhong liu Zhiguang Zhou Qiangkun Zhan National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials South China University of TechnologyGuangzhou 510641China

Grain refinement is critical to surpassing the bottlenecks of inherent hot tearing of high-strength aluminum alloys fabricated by additive manufacturing(AM).In this study,a synergistic grain-refining strategy including heterogeneous nucleation,solute-driven growth restriction and nanoparticle-induced growth restriction was introduced to control the microstructure of Al-Zn-Mg-Cu alloys during the laser powder bed fusion(LPBF)***-free Al-Zn-Mg-Cu alloys with significantly refined grains were safely fabricated via LPBF by coincorporation of Ti C and ***-situ L1-AlTi particles were produced to promote the heterogeneous *** grain growth was restricted by adding Ti solute,while introduced TiC nanoparticles(NPs)improved the density of heterogeneous nucleation sites and blocked grain growth *** resultant elimination of columnar grains and hot cracks in the(1 wt.%)TiC-and(0.8 wt.%)TiH-modified Al-Zn-Mg-Cu alloy resulted in excellent ultimate tensile strength(UTS)of 593±24 MPa,yield strength(YS)of 485±41 MPa and elongation(EL)of 10.0%±2.5%under the T6 *** study provides new insights into improving the grain microstructure and mechanical properties of high-strength aluminum alloys during LPBF.

关键词： Grain refinement High-strength aluminum alloys Laser powder bed fusion(LPBF) Al-Zn-Mg-Cu alloy

One-pot synthesis of Cu:InP multishell quantum dots for nearinfrared light-emitting devices

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Nano Research 2024年第12期17卷 10655-10660页

作者： Pan Huang Xiaonan liu Xiao liu Jing Wei Fangze liu Hongbo Li Advanced Research Institute of Multidisciplinary Sciences Beijing Institute of TechnologyZhuhai 519088China Advanced Research Institute of Multidisciplinary Sciences Beijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory of Construction-Tailorable Advanced Functional Materials and Green Applications Experimental Center of Advanced MaterialsSchool of Materials Science and EngineeringBeijing Institute of TechnologyBeijing 100081China

InP quantum dots(QDs)are promising heavy-metal-free materials for next-generation solid-state lighting,covering from visible to near-infrared(NIR)*** with the rapid development of visible InP QDs,the synthesis of high-performance NIR InP QDs remains to be *** this work,we report a simple one-pot synthesis of NIR InP QDs by controlling the Cu doping and designing a multishell *** replacing the conventional highly reactive phosphorus precursor with a slightly less reactive and low-cost ammonia phosphorus precursor,the nucleation process is effectively regulated for efficient Cu *** addition,the epitaxial growth of the ZnSe/ZnS shell further improves the stability and optical properties of InP ***,the synthesized Cu:InP/ZnSe/ZnS QDs have a photoluminescence quantum yield of 70%centered at 833 *** NIR InP lightemitting diodes exhibit a maximum radiance of 3.1 W·sr^(-1)·m^(-2)and a peak external quantum efficiency of 2.71%centered at 864 nm.

关键词： near-Infrared InP quantum dots core-shell light-emitting diodes

Effects of N-alkylation on anticorrosion performance of doped polyaniline/epoxy coating

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Journal of Materials Science & Technology 2020年第4期39卷 48-55页

作者： Suyun liu Li liu Ying Li Fuhui Wang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Material Science and EngineeringNortheastern UniversityShenyang 110819China

N-alkylation of sulfosalicylic acid-doped polyaniline(PANI-SSA)was used to promote the anticorrosion performance of PANI-SSA/epoxy coating for 5083 Al ***-SSA was modified with C5H11Br and C12H25Br in polar solvents IPA(isopropanol)and DMF(dimethylformamide),and then characterized by FTIR,XPS and sedimentation *** showed that alkanes were successfully linked onto the PANI-SSA *** compatibility between N-alkylated PANI-SSA and epoxy/xylene solution was *** results proved a better dispersion performance of N-alkylated PANI-SSA in epoxy coatings,with less holes and *** protection of the epoxy coatings incorporating PANI-SSA and N-alkylated PANI-SSA on 5083 Al alloy was studied by EIS and adhesion measurements in 3.5%NaCl *** turned out that the epoxy coating including C12H25Br-modified PANI-SSA in DMF has yielded the highest values of impedance modulus and best protective properties.

关键词： Polyaniline Coating Modification Al alloy Anticorrosive property

Improved mesh-free SPH approach for loose top coal caving modeling

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Particuology 2024年第12期95卷 1-27页

作者： Xiangwei Dong Qiang Zhang Yang liu Xin liu College of Mechanical and Electronic Engineering Shandong University of Science and TechnologyQingdao266590China Shaanxi Coal Group Shenmu Hongliulin Mining Co. LtdYulin719314China

This study presents an innovative model in computational geotechnical engineering by improving the Smoothed Particle Hydrodynamics(SPH)method for simulating loose particle dynamics in coal caving *** improved model integrates an elastic-perfectly plastic constitutive model with the Drucker-Prager yield criterion and includes several improvements aimed at boosting accuracy,stability,and *** improvements include gravity loading coupled with particle damping,first-order stress field smoothing,and kernel gradient correction.A series of numerical experiments validates the effectiveness of the improved SPH model,demonstrating its capability to predict large deformations and track the evolution of the coal-rock interface in coal caving ***,the study analyzes the model's sensitivity to material parameters such as the angle of friction and material density,which aids in configuring the model for distinct coal mining *** show that the non-cohesive elastic-perfectly plastic constitutive model can effectively simulate the flow behavior of granular particles,and the landslide simulation results are in good agreement with the *** improved SPH algorithm with stress smoothing technique solves the problem of numerical noise,and the“double peak”stress distribution around the coal outlet is *** established SPH model offers an effective tool for understanding dynamics behaviors of loose top ***,the model requires only five material parameters,which can be identified through standard experiments,avoiding the typically arduous process of parameter selection or calibration commonly existing in Discrete Element Method simulations.

关键词： Smoothed particle hydrodynamics(SPH) Top coal caving Loose coal and rock particles Elastic-perfectly plastic constitutive model Model sensitivity analysis

Fracture Prediction for an Advanced High-Strength Steel Sheet Using the Fully Coupled Elastoplastic Damage Model with Stress-State Dependence

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Acta Mechanica Solida Sinica 2021年第2期34卷 263-273页

作者： Kai Zhang Mingchuan Wang Weijie liu Jianlin liu College of Pipeline and Civil Engineering China University of Petroleum(East China)Qingdao 266580China Sino-French Engineer School Nanjing University of Science and TechnologyNanjing 210094China Institute of Applied Physics and Computational Mathematics Beijing 10094China

In this study,the numerical simulations of sheet metal forming processes are performed based on a fully coupled elastoplastic damage *** effects of stress triaxiality and Lode angle are introduced into the damage evolution law to capture the loading-path-dependent *** proposed constitutive model is implemented into the finite element(FE)code ABAQUS/Explicit via the user-defined subroutine(VUMAT).Next,the identification procedure for DP780 based on the hybrid experimental-numerical method is presented in *** numerical results of simple tests are compared with the experiments,and obvious improvement is observed for the proposed model under various loading ***,the model is applied to predict the edge fracture during sheet blanking *** predicted global load–displacement responses and crack paths have a good agreement with the experimental results,indicating that the model holds great potentials in simulation of metal forming processes.

关键词： Ductile damage Full coupling Stress state Numerical simulation Edge fracture