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Wuhan University Journal of natural Sciences 2024年第3期29卷 242-256页

作者： LIU Jinyu WAnG biao CHAnG Caihong College of Science Xi'an University of Science and TechnologyXi'an 710054ShaanxiChina

This paper is concerned with radially positive solutions of the k-Hessian equation involving a Matukuma-type source S_(k)(D^(2)(-φ))=|x|^(λ-2)/(1+|x|^(2))^(λ2)φ^(q),x∈Ω,where S_(k)(D^(2)(-φ))is the k-Hessian operator,q>k>1,λ>0,n>2k,k∈n,andΩis a suitable bounded do-main in R~*** turns out that there are two different types of radially positive solutions for k>1,i.e.,M-solution(singular at r=0)and Esolution(regular at r=0),which is distinct from the case when k=*** 1n-2+λ)k](n-2k),we apply an iterative approach to improve accuracy of asymptotic expansions of M-solution step by step to the desired *** contrast to the case k=1,we require a more precise range of parameters due to repeated application of Taylor expansions,which also makes asymptotic expansions need more delicate investigation.

关键词： k-Hessian equation singular solutions asymptotic expansion

Hemispherical resonator with low subsurface damage machined by small ball-end fine diamond grinding wheel:A novel grinding technique

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Chinese Journal of Aeronautics 2024年第5期37卷 570-585页

作者： biao QIn Henan LIU Jian CHEnG Jinchuan TIAn Jiangang SUn Zihan ZHOU Chuanzhen MA Mingjun CHEn State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China Center for Precision Engineering Harbin Institute of TechnologyHarbin 150001China

As for the ultra-precision grinding of the hemispherical fused silica resonator,due to the hard and brittle nature of fused silica,subsurface damage(SSD)is easily generated,which enormously influences the performance of such ***,ultra-precision grinding experiments are carried out to investigate the surface/subsurface quality of the hemispherical resonator machined by the small ball-end fine diamond grinding *** influence of grinding parameters on the surface roughness(SR)and SSD depth of fused silica samples is then *** experimental results indicate that the SR and SSD depth decreased with the increase of grinding speed and the decrease of feed rate and grinding *** addition,based on the material strain rate and the maximum undeformed chip thickness,the effect of grinding parameters on the subsurface damage mechanism of fused silica samples is ***,a multi-step ultra-precision grinding technique of the hemispherical resonator is proposed based on the interaction influence between grinding depth and feed ***,the hemispherical resonator is processed by the proposed grinding technique,and the SR is improved from 454.328 nm to 110.449 nm while the SSD depth is reduced by 94%from 40μm to 2.379μ*** multi-step grinding technique proposed in this paper can guide the fabrication of the hemispherical resonator.

关键词： Fused silica Ultra-precision grinding Hemispherical resonator Subsurface damage Grinding technique

Multicolor emission from lanthanide ions doped lead-free Cs_(3)Sb_(2)Cl_(9) perovskite nanocrystals

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Journal of Rare Earths 2024年第5期42卷 940-946,I0005页

作者： He Shao Lifang Li Xiufeng Wu Lin Xu biao Dong Donglei Zhou Xue Bai Hongwei Song State Key Laboratory of Organic Electronics and Information Displays&Institute of Advanced Materials College of Materials Science and EngineeringNanjing University of Posts&TelecommunicationsNanjing210023China State Key Laboratory of Integrated Optoelectronics College of Electronic Science and Engineering Jilin UniversityChangchun130012China

The toxicity of lead ions has become the severe challenge for the all-inorganic lead halide p erovskite materials,although some works have rep orted the lead-free perovskite nanocrystals(nCs),the photoluminescence quantum yield(PLQY)of these materials is still ***,because the halogen ions can be easily exchanged,the controllable multicolor emission in perovskite nCs is difficult to realize in current *** this work,we introduced lanthanide ions into lead-free Cs_(3)Sb_(2)Cl_(9) perovskite *** from the energy transfer between Cs_(3)Sb_(2)Cl_(9) perovskite nC host and lanthanide ions,the multicolor emission was *** on controlling the doping concentration of Tb^(3+)and Eu^(3+)ions,the white light emission under UV excitation would be turned easily in the Tb^(3+)/Eu^(3+)codoped *** addition,efficient energy transfer from perovskite nCs to Tb^(3+)or Eu^(3+)ions is beneficial to improving the optical properties of lead-free perovskite nCs,resulting in maximum PLQYs of red,green and white light emission of 22.6%,19.7%and 28.5%,***,a white light emitting device(WLED)was fabricated with a power efficiency of 18.5 lm/W,which presents the Commission Internationale de l'Eclairage(CIE)of(0.33,0.35).

关键词： Perovskite nanocrystals Lead free Lanthanide ions Energy transfer White light emitting device Rare earths

Design strategies of high-performance lead-free electroceramics for energy storage applications

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Rare Metals 2024年第3期43卷 853-878页

作者： biao Guo Fei Jin Li Li Zi-Zhao Pan Xin-Wei Xu Hong Wang Department of Materials Science and Engineering College of EngineeringSouthern University of Science and TechnologyShenzhen518055China School of Microelectronics and State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an710049China

A greater number of compact and reliable electrostatic capacitors are in demand due to the Internet of Things boom and rapidly growing complex and integrated electronic systems,continuously promoting the development of high-energy-density ceramic-based *** significant successes have been achieved in obtaining high energy densities in lead-based ferroelectric ceramics,the utilization of lead-containing ceramies has been restricted due to environmental and health hazards of ***-free ferroelectric ceramics have garnered tremendous attention and are expected to replace lead-based ceramics in the near ***,the energy density of lead-free ceramics is still lagging behind that of lead-containing ***,severely limiting their *** efforts have been made to enhance the energy storage performance of lead-free ceramics using multi-scale design strategies,and exciting progress has been achieved in the past *** review briefly discusses the energy storage mechanism and fundamental characteristics of a dielectric capacitor,summarizes and compares the state-of-the-art design strategies for high-energy-density lead-free ceramics,and highlights several critical issues and requirements for industrial *** prospects and challenges of lead-free ceramics for energy storage applications are also discussed.

关键词： Dielectric materials Lead-free ceramic Environment friendly Energy storage Design strategy

Garnet and Zircon U-Pb Geochronology and Geochemistry Reveal Genesis of the Dafang Au-Pb-Zn-Ag Deposit,Southern Hunan

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Acta Geologica Sinica(English Edition) 2024年第3期98卷 717-735页

作者： JIAnG Hua KOnG Hua LIU biao TAn Fucheng QIn Yixue HUAnG Jingang ZHU Yu Key Laboratory of Metallogenic Prediction of nonferrous Metals and Geological Environment Monitoring Ministry of EducationSchool of Geosciences and Info-PhysicsCentral South UniversityChangsha 410083China School of Geosciences and Info-Physics Central South UniversityChangsha 410083China Hunan Baoshan nonferrous Metals and Minerals Co. Ltd.ChenzhouHunan 424402China

Garnet is a primary mineral in skarn deposits and plays a significant role in recording copious mineralization and metallogenic *** study systematically investigates the geochemistry and geochronology of garnet and zircon in the Dafang Au-Pb-Zn-Ag deposit,which represents prominent gold mineralization in southern Hunan,*** samples with distinct zoning patterns and compositional variations were identified using various analytical techniques,including Backscattered Electron(BSE)imaging,Cathodoluminescence(CL)response,textural characterization,and analysis of rare-earth elements(REE),major contents,and trace element *** garnet was dated U-Pb dating,which yielded a lower intercept age of 161.06±1.93 *** age is older than the underlying granodiorite porphyry,which has a concordia age of 155.13±0.95 Ma determined by zircon U-Pb *** results suggest that the gold mineralization may be related to the concealed *** groups of garnet changed from depleted Al garnet to enriched Al garnet,and the rare earth element(REE)patterns of these groups were converted from light REE(LREE)-enriched and heavy REE(HREE)-depleted with positive europium(Eu)anomalies to medium REE(MREE)-enriched from core to rim *** different REE patterns of garnet in various zones may be attributed to changes in the fluid environment and late superposition *** development of distal skarn in the southern Hunan could be a significant indicator for identifying gold mineralization.

关键词： garnet and zircon U-Pb dating LA-ICP-MS mapping Dafang Southern Hunan

Improving flight performance of UAVs by ice shape modulation

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Chinese Journal of Aeronautics 2024年第8期37卷 49-62页

作者： Jiajun ZHAnG Xuecheng LIU Hua LIAnG Like XIE biao WEI Haohua ZOnG Yun WU Yinghong Li national Key Lab of Aerospace Power System and Plasma Technology Air Force Engineering UniversityXi’an 710038China Institute of Aero-Engine School of Mechanical EngineeringXi’an Jiaotong UniversityXi’an 710049China

Aircraft icing poses a great threat to flight *** response to the characteristics of high-power consumption,large volume,and heavy weight of traditional anti-/de-icing technologies,the concept of ice shape modulation is proposed,which is called ice tolerant ***,the flight performance of Unmanned Aerial Vehicle(UAV)was compared in three states:no ice,full ice,and modulated ice through flight *** was found that ice shape modulation has a significant improvement effect on the aerodynamic performance of aircraft under icing *** the three modulated ice shape conditions in this experiment,the lift coefficient of the UAV under different ice shape modulation conditions increased by 18%–33%,and the stalling angle was delayed by 3°-5°.Subsequently,the pressure distribution,streamlines in the flow field,and detached vortex distribution of the UAV model in these three states were obtained through numerical simulation,to study the mechanism of ice shape modulation on the aerodynamic performance of *** simulation found that the reason for the improvement of the wings effect after ice shape modulation is that the modulated area forms a leading-edge protrusion structure similar to a vortex *** structure prolongs the mixed flow region on the wings surface and reduces the trend of flow separation,which plays a role in increasing lift and reducing drag for UAVs under icing ***,a reverse reachable set that can be used for unexpected state recovery is used as the definition of flight safety boundaries,and an aircraft dynamics model is established to obtain flight safety boundaries for different *** has found that the flight safety boundary of the UAV in a no ice state is greater than that in a modulated ice state,and the safety boundary in a modulated ice state is greater than that in a full ice *** with the full ice state,the flight safety boundary after modulation has expanded by 27.0%.The sch

关键词： Ice shape modulation Aerodynamic performance Reachable set Flight safety UAV

Extraction and recycling technologies of cobalt from primary and secondary resources:A comprehensive review

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International Journal of Minerals,Metallurgy and Materials 2024年第4期31卷 628-649页

作者： Yukun Huang Pengxu Chen Xuanzhao Shu biao Fu Weijun Peng Jiang Liu Yijun Cao Xiaofeng Zhu ZhongYuan Critical Metals Laboratory Zhengzhou UniversityZhengzhou 450001China State Key Laboratory of Advanced Processing and Recycling of nonferrous Metals Lanzhou University of TechnologyLanzhou 730050China

Cobalt has excellent electrochemical,magnetic,and heat *** a strategic resource,it has been applied in many hightech ***,the recent rapid growth of the battery industry has substantially depleted cobalt resources,leading to a crisis of cobalt resource *** paper examines cobalt ore reserves and distribution,and the recent development and consumption of cobalt resources are summarized as *** addition,the principles,advantages and disadvantages,and research status of various methods are discussed *** can be concluded that the use of diverse sources(Cu-Co ores,ni-Co ores,zinc plant residues,and waste cobalt products)for cobalt production should be enhanced to meet developmental ***,in recovery technology,the pyro-hydrometallurgical process employs pyrometallurgy as the pretreatment to modify the phase structure of cobalt minerals,enhancing its recovery in the hydrometallurgical stage and facilitating high-purity cobalt ***,it represents a promising technology for future cobalt ***,based on the above conclusions,the prospects for cobalt are assessed regarding cobalt ore processing and sustainable cobalt recycling,for which further study should be conducted.

关键词： cobalt recovery copper-cobalt ore nickel-cobalt ore zinc plant residue waste cobalt products

Research advance of Bacillus velezensis:bioinformatics,characteristics,and applications

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Food Science and Human Wellness 2024年第4期13卷 1756-1766页

作者： Ting Su biao Shen Xingjuan Hu Yue Teng Peifang Weng Zufang Wu Lianliang Liu State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products Key Laboratory of Animal Protein Deep Processing Technology of ZhejiangZhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and NutritionSchool of Food and Pharmaceutical SciencesNingbo UniversityNingbo 315000China Zhoushan Customs District Zhoushan 316100China

Bacillus velezensis is a Gram-positive and spore-forming *** has potent antimicrobial properties that can be used to promote plant growth and as a pesticide by inhibiting *** has the capability to generate a diverse range of enzymes that have potential applications in various fields,such as enzyme production,fermented food,degradation of pollutants,and *** addition,*** is a promising *** possesses high bile-salt tolerance characteristics and has a high success rate of colonization in the intestinal ***,the strain can also regulate gut microbiota constitute by increasing the number of beneficial microorganisms and decreasing the number of ***,based on its special properties,including high-yield protease production and high salt-tolerance,*** shows potential for use in marine protein fermentation,opening up new avenues for the development of novel food products and bioactive *** addition,*** can shorten the fermentation time as well as improve the nutritional value and flavor of fermented *** safety of *** for food production was *** review provides valuable insights into the potential uses and benefits of ***,particularly in the context of fermented foods.

关键词： Bacillus velezensis Bioinformatics Properties Fermentation Bioactive peptides

Observation and analysis of positive leader re-illumination in a 10 m ultra-high voltage transmission line gap under switching impulse voltages

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Plasma Science and Technology 2024年第10期26卷 93-100页

作者： biao HUAnG Xuan ZHOU She WAnG Chijie ZHUAnG Rong ZEnG Le DEnG Eliet Engineering School Changsha University of Science&TechnologyChangsha 410114People’s Republic of China State Key Laboratory of Disaster Prevention&Reduction for Power Grid Changsha University of Science&TechnologyChangsha 410114People’s Republic of China China International Engineering Consulting Co. Ltd.Beijing 100048People’s Republic of China Department of Electrical Engineering Tsinghua UniversityBeijing 100084People’s Republic of China

The leader propagation is one of the most important stages in long air gap *** mechanism behind leader re-illumination remains *** high humidity conditions(20.0–30.1 g/m^(3)),we have conducted experiments of long sparks in a 10 m ultra-high voltage(UHV)transmission line gap under switching impulse *** positive leaders predominantly propagate discontinuously,with almost no significantly continuous propagation *** leader channels are intensely luminous and each elongation segment is straight,with streamers resembling the“branch type”which differs from the“diffuse type”streamers at the front of continuous propagation *** distribution of the propagation velocities is highly random(3.7–18.4 cm/μs),and the average velocity(9.2 cm/μs)significantly exceeds that of continuous propagation(1.5–2.0 cm/μs).Analysis suggests that the current-velocity models suitable for continuous leader propagation do not align well with the experimental data in re-illumination *** on the discharge current waveforms and optical images,it is speculated that the newly elongated leader in re-illumination mode does not evolve gradually from the stem(about 1 cm)but rather evolves overall from a thermal channel much longer than stem.

关键词： long air gap discharge positive leader re-illumination discontinuous leader propagation