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Ultra-broadband microwave absorber and high-performance pressure sensor based on aramid nanofiber,polypyrrole and nickel porous aerogel

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International Journal of Minerals,Metallurgy and Materials 2024年第8期31卷 1912-1921页

作者： Leyi Zhang Hongyu Jin Hanxin Liao Rao Zhang Bochong Wang Jianyong Xiang Congpu Mu Kun Zhai Tianyu Xue Fusheng Wen State key laboratory of Metastable Materials science&technology Yanshan UniversityQinhuangdao 066004China key laboratory for Microstructural Material Physics of Hebei Province School of ScienceYanshan UniversityQinhuangdao 066004China

Electronic devices have become ubiquitous in our daily lives,leading to a surge in the use of microwave absorbers and wearable sensor devices across various sectors.A prime example of this trend is the aramid nanofibers/polypyrrole/nickel(APN)aerogels,which serve dual roles as both microwave absorbers and pressure *** this work,we focused on the preparation of aramid nanofibers/polypyrrole(AP15)aerogels,where the mass ratio of aramid nanofibers to pyrrole was 1:*** employed the oxidative polymerization method for the preparation *** this,nickel was thermally evaporated onto the surface of the AP15 aerogels,resulting in the creation of an ultralight(9.35 mg·cm^(-3)).This aerogel exhibited a porous *** introduction of nickel into the aerogel aimed to enhance magnetic loss and adjust impedance matching,thereby improving electromagnetic wave absorption *** minimum reflection loss value achieved was-48.7 dB,and the maximum effective absorption bandwidth spanned 8.42 GHz with a thickness of 2.9 *** impressive metrics can be attributed to the three-dimensional network porous structure of the aerogel and perfect impedance ***,the use of aramid nanofibers and a three-dimensional hole structure endowed the APN aerogels with good insulation,flame-retardant properties,and compression *** under a compression strain of 50%,the aerogel maintained its resilience over 500 *** incorporation of polypyrrole and nickel particles further enhanced the conductivity of the ***,the final APN aerogel sensor demonstrated high sensitivity(10.78 kPa-1)and thermal *** conclusion,the APN aerogels hold significant promise as ultra-broadband microwave absorbers and pressure sensors.

关键词： porous aerogel aramid nanofibers microwave absorbers pressure sensor porous structure

Achieving Narrowed Bandgaps and Blue-Light Excitability in Zero-Dimensional Hybrid Metal Halide Phosphors via Introducing Cation-Cation Bonding

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Energy & Environmental Materials 2024年第1期7卷 294-300页

作者： Pengfei Fu Shining Geng Ruixiang Mi Ranyun Wu Guangya Zheng Binbin Su Zhiguo Xia Guangda Niu Jiang Tang Zewen Xiao Wuhan National laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China The State key laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied TechniquesSchool of Materials Science and TechnologySouth China University of TechnologyGuangzhou 510640China School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074China

Zero-dimensional(0D)hybrid metal halides,which consist of organic cations and isolated inorganic metal halide anions,have emerged as phosphors with efficient broadband ***,these materials generally have too wide bandgaps and thus cannot be excited by blue light,which hinders their applications for efficient white light-emitting diodes(WLEDs).The key to achieving a blue-light-excitable 0D hybrid metal halide phosphor is to reduce the fundamental bandgap by rational chemical *** this work,we report two designed hybrid copper(I)iodides,(Ph_(3)MeP)_(2)Cu_(4)I_(6)and(Cy_(3)MeP)_(2)Cu_(4)I_(6),as blue-light-excitable yellow phosphors with ultrabroadband *** these compounds,the[Cu_(4)I_(6)]^(2-)anion forms an I6 octahedron centered on a cationic Cu_(4)*** strong cation-cation bonding within the unique cationic Cu_(4)tetrahedra enables significantly lowered conduction band minimums and thus narrowed bandgaps,as compared to other reported hybrid copper(I)*** ultrabroadband emission is attributed to the coexistence of free and self-trapped *** WLED using the[Cu_(4)I_(6)]^(2-)anion-based single phosphor shows warm white light emission,with a high luminous efficiency of 65 Im W^(-1)and a high color rendering index of *** work provides strategies to design narrow-bandgap 0D hybrid metal halides and presents two first examples of blue-light-excitable 0D hybrid metal halide phosphors for efficient WLEDs.

关键词： blue-light-excitable cation-cation bonding hybrid metal halide phosphor zero-dimensional

A deep learning model enabled multi-event recognition for distributed optical fiber sensing

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science China(Information sciences) 2024年第3期67卷 291-307页

作者： Yujiao LI Xiaomin CAO Wenhao NI Kuanglu YU Institute of Information science School of Computer and Information TechnologyBeijing Jiaotong University Beijing key laboratory of Advanced Information science and Network technology Beijing Jiaotong University

Fiber optic sensors that utilize backscattered light offer distributed real-time measurements and have been seen tremendous improvements in sensing distance and spatial resolution over the last ***, these improvements in sensor capabilities lead to a significant increase in the amount of data that needs to be processed. Traditional processing schemes are no longer adequate, so the development of novel signal processing methods is critical. Phase-sensitive optical time domain reflectometry(Φ-OTDR) is now applied in various applications for multi-event recognition, and it would usually be difficult, sometimes even unrealistic to label all the acquired samples due to its real-time and seamless monitoring nature. To fully take advantage of the information contained within the large number of unlabeled samples, which were formerly not utilized and hence wasted, we propose a semi-supervised model to boost the event classification performance of Φ-OTDR. The model extracts respectively the temporal features and the spatial bidirectional features together with a dual attention mechanism. Its classification accuracy has been improved up to 96.9%with only 1230 labeled samples. In addition, our model shows significant advantages when the number of labeled samples is reduced. Importantly, our method improves the accuracy of multi-event classification without any modification to the optical setup.

关键词： $\Phi$-OTDR event recognition semi-supervised learning mean teacher MT-ACNN-SA-BiLSTM

Surface integrity evolution during creep feed profile grinding ofγ-TiAl blade tenon

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Chinese Journal of Aeronautics 2024年第8期37卷 496-512页

作者： Tao CHEN Xiaowei WANG Biao ZHAO Wenfeng DING Jiuhua XU National key laboratory of science and technology on Helicopter Transmission Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Gamma titanium-aluminum(γ-TiAl)intermetallic compounds are increasingly used in manufacturing key hot-end components(e.g.,blade tenon)in aero engines due to their high specific strength and lightweight *** feed profile grinding(CFPG)as a crucial precision process that is applied to produce the final profile of the blade ***,sudden surface burns and microcracks of machined c-TiAl blade tenon often occur because of its low plasticity and high strength during grinding processes,leading to poor surface *** this work,CFPG experiments based on the profile characteristics ofγ-TiAl blade tenon were performed and an associated undeformed chip thickness model considering grain–workpiece contact condition was established to explore the evolution of the surface ***,the surface integrity was analyzed at different positions of the blade tenon in terms of surface roughness and morphology,metallographic structure,microhardness,and residual *** show that the profile characteristics of blade tenon have a significant influence on machined surface integrity because of the thermomechanical effect at various detecting *** residual stress was established based on the undeformed chip thickness model considering the profile structure,with a prediction error of 10%–15%.The thermomechanical effect is more obvious at the bottom area,where the surface roughness,work hardening degree,and subsurface plastic deformation range are the largest,while the values at the bevel area are the *** on the undeformed chip thickness model,a residual stress finite element simulation was conducted by employing thermomechanical coupled *** addition,the error between the simulation and the experiment was between 10%–15%.Strain and strain rate equations were established through the relationship between material displacement and *** average strain and strain rate of the ground surface when ap is 1.0 mm are 18.8%and 33.2%l

关键词： Gamma titanium-aluminum intermetallic compounds Blade tenon Creep feed profile grinding Surface integrity Thermomechanical effect

New quantification of symmetry energy from neutron skin thicknesses of 48Ca and 208Pb

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Nuclear science and Techniques 2024年第10期35卷 217-225页

作者： Rong An Shuai Sun Li-Gang Cao Feng-Shou Zhang School of Physics Ningxia University key laboratory of Beam technology of the Ministry of Education College of Nuclear Science and TechnologyBeijing Normal University key laboratory of Beam technology of the Ministry of Education Institute of Radiation TechnologyBeijing Academy of Science and Technology Center of Theoretical Nuclear Physics National Laboratory of the Heavy Ion Accelerator of Lanzhou

Precise knowledge of the nuclear symmetry energy can be tentatively calibrated using multimessenger *** neutron skin thickness of a heavy nucleus is one of the most sensitive indicators for probing the isovector components of effective interactions in asymmetric nuclear *** studies have suggested that the experimental data from the CREX and PREX2 collaborations are not mutually compatible with existing nuclear *** this study,we review the quantification of the slope parameter of the symmetry energy L from the neutron skin thicknesses of48Ca *** energy density functionals classified by various isoscalar incompressibility coefficients K were employed to evaluate the bulk properties of finite *** calculated results suggest that the slope parameter L deduced from208Pb is sensitive to the compression modulus of symmetric nuclear matter,but not that *** effective parameter sets classified by K=220 MeV can provide an almost overlapping range of L from48Ca and208Pb.

关键词： Energy density functional Neutron skin thickness Nuclear symmetry energy

Effect of nanofillers with different energy levels on the electrical properties of epoxy‐based nanocomposites

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High Voltage 2024年第4期9卷 948-956页

作者： Ning Guo Cailing Chen Guangwei Zhang Rongsheng Sun Yulong Wang Junguo Gao key laboratory of Engineering Dielectrics and Its Application Ministry of EducationHarbin University of Science and TechnologyHarbinChina

The authors investigate the effects of nanofillers with varying band‐gap energies on the space charge properties,breakdown field strength,and bulk resistivity of epoxy(EP)‐based ***,the molecular orbital distribution of both the epoxy resin and nanofillers were examined through density functional *** results indicate that the space charge accumulation within silicon dioxide/EP and germanium oxide/EP is reduced,leading to a more uniformly distributed electric field intensity within the specimen when compared to *** a result,both materials exhibit improved AC breakdown field strength and volume ***,the amount of charge accumulated within tin dioxide/EP is higher,resulting in lower breakdown field strength than *** lowest unoccupied molecular orbital and the highest occupied molecular orbital energy level differences between epoxy and nanofillers introduce electron traps and hole traps at the interface,forming interfacial traps that affect the space charge distribution within the specimen,as well as the trap energy levels within the *** the experimental results,shallow traps promote space charge accumulation and reduce the breakdown field strength,while deep traps have the opposite effect.

关键词： energy resistivity occupied

Rapid and controllable in-situ self-assembly of main-group metal nanofilms for highly efficient CO_(2)electroreduction to liquid fuel in flow cells

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Nano Research 2024年第6期17卷 5718-5725页

作者： Miao Wang Huaizhu Wang Yaoda Wang Junchuan Liang Mengfei Zhu Jiarui Li Zuoxiu Tie Zhong Jin State key laboratory of Coordination Chemistry MOE Key Laboratory of Mesoscopic ChemistryMOE Key Laboratory of High Performance Polymer Materials and TechnologyJiangsu Key Laboratory of Advanced Organic MaterialsTianchang New Materials and Energy Technology Researc

The electrocatalytic reduction of CO_(2)is a promising pathway to generate renewable fuels and ***,its advancement is impeded by the absence of electrocatalysts with both high selectivity and ***,we present a scalable in-situ thermal evaporation technique for synthesizing series of Bi,In,and Sn nanofilms on carbon felt(CF)substrates with a high-aspect-ratio *** resulting main-group metal nanofilms exhibit a homogeneously distributed and highly exposed catalyst surface with ample active sites,thereby promoting mass transport and ad-/desorption of reaction *** from the unique fractal morphology,the Bi nanofilms deposited on CF exhibit optimal catalytic activities for CO_(2)electroreduction among the designed metal nanofilms electrodes,with the highest Faradaic efficiency of 96.9%for formate production at−1.3 V *** hydrogen electrode(RHE)in *** an industrially relevant current density of 221.4 mA·cm−2 in flow cells,the Bi nanofilms retain a high Faradaic efficiency of 81.7%at−1.1 V(***)and a good long-term stability for formate ***,a techno-economic analysis(TEA)model shows the potential commercial viability of electrocatalytic CO_(2)conversion into formate using the Bi nanofilms *** results offer a green and convenient approach for in-situ fabrication of stable and inexpensive thin-film catalysts with a fractal structure applicable to various industrial settings.

关键词： CO_(2)electroreduction non-noble metal nanofilms flow cells efficiency and selectivity techno-economic analysis

Global Solvability for a Predator-Prey Model with Prey-Taxis and Rotational Flux Terms

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Chinese Annals of Mathematics,Series B 2024年第2期45卷 297-318页

作者： Guoqiang REN Bin LIU School of Mathematics and Statistics Huazhong University of Science and Technology Hubei key laboratory of Engineering Modeling and Scientific Computing Huazhong Universityof Science and Technology

In this paper the author investigates the following predator-prey model with prey-taxis and rotational?ux terms■in a bounded domain with smooth *** presents the global existence of generalized solutions to the model... 详细信息

关键词： Predator-prey Prey-taxis Giopal existence Kotational flnux

Optimal V_(2)O_(3) extraction by sustainable vanadate electrolysis in molten salts

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Tungsten 2024年第1期6卷 141-149页

作者： Bao-Yan Feng Zhong-Hua Zhao Yong-Zheng Jia Jia-Liang An Ming-Yong Wang State key laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China Beijing key laboratory of Green Recovery and Extraction of Rare and Precious Metals University of Science and Technology BeijingBeijing 100083China

Recently,an environmentally friendly electrolysis process of soluble vanadates is proposed and successfully confirmed for V_(2)O_(3) *** this paper,the solubilities of various vanadates(***_(3),Na_(4)V_(2)O_(7) and Na_(3)VO_(4))in NaCl molten salt are *** dependences of V_(2)O_(3) extraction on vanadate form,anode material and molten salt system are studied.A long-term electrolysis is carried *** result indicates that the solubilities of all vanadates are high and meet electrolytic *** to Na_(4)V_(2)O_(7) and Na_(3)VO_(4),NaVO_(3) exhibits larger current efficiency and lower electricity *** using SnO_(2) anode instead of graphite anode,the current efficiency of NaVO_(3) electrolysis can be increased to 58.1%and carbon pollution is avoided at 700℃.The extraction rate of V_(2)O_(3) reaches 81.3%after long-term electrolysis of 51 *** work optimizes the electrochemical preparation process of V_(2)O_(3) from various vanadates and contributes to the improvement of current efficiency and extraction rate.

关键词： Molten salt electrolysis Vanadate Vanadium trioxide Current efficiency