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Hard yet tough and self-lubricating(CuNiTiNbCr)C_(x) high-entropy nanocomposite films:Effects of carbon content on structure and properties

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Journal of materials Science & Technology 2024年第6期173卷 20-30页

作者： y.T.Li X.m.chen X.K.Zeng m.Liu X.Jiang y.X.Leng Key Laboratory of Advanced Technologies of materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China Key Laboratory of Noise and Vibration Research Institute of AcousticsChinese Academy of SciencesBeijing 100190China State Key Laboratory of Acoustics Institute of AcousticsChinese Academy of SciencesBeijing 100190China School of mechanical and Electrical Engineering Mianyang Teachers’CollegeMianyang 621000China

The single-phase high-entropy alloy film is difficult to meet severe friction conditions due to its low hardness and high friction ***-composite structure film is composed of at least two separated phases,showing the properties of strength and toughness integration and excellent wear *** design of nanocomposite structures can effectively improve the mechanical properties and tribological properties of high-entropy alloy *** this study,the(CuNiTiNbCr)C_(x) nanocomposite high-entropy films(HEFs)integrated with high hardness,high toughness,and self-lubrication were synthesized by the double-target co-sputtering *** effect of carbon content on microstructure,mechanical properties,and tribological properties of(CuNiTiNbCr)C_(x) films was *** the increase of carbon content in the HEFs,the carbon atoms preferentially react with Ti,Nb,and Cr to form a(TiNbCr)C ceramic-reinforced phase,and then the excess carbon atoms precipitate in the form of amorphous carbon(a-C)lubricating phase in the *** structure of the HEFs changes from an amorphous structure to a nanocomposite structure of amorphous(amorphous CuNiTiNbCr phase+a-C phase)/nanocrystalline(TiN-bCr)C *** the carbon content is about 21.2 at.%,the carbide phase in the film reaches saturation and the hardness and modulus of the films are highest,which are 18 GPa and 228 GPa,*** HEFs with a carbon content of 44.0 at.%show the best toughness and tribological properties with a friction coefficient of 0.16 and a wear rate of 2.4×10^(-6) mm^(3)/(N m),which is mainly attributed to the excellent resistance to fatigue crack growth and the interfacial lubricating layer formed in the friction *** nanocomposite(CuNiTiNbCr)C_(x) HEFs show very promising application prospect in the field of friction protection.

关键词： High-entropy films Nanocomposite Double-target co-sputtering Strengthening-toughening Tribological properties

Single-pilot operations in commercial flight:Effects on neural activity and visual behaviour under abnormalities and emergencies

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Chinese Journal of Aeronautics 2024年第8期37卷 277-292页

作者： Qinbiao LI Chun-Hsien chen Kam K.H.ng Xin yUAN Cho yin yIU Human Factors and Ergonomics Laboratory Department of Aeronautical and Aviation EngineeringThe Hong Kong Polytechnic UniversityHong Kong Special Administrative Region 100872China School of mechanical&Aerospace Engineering Nanyang Technological UniversitySingapore 639798Singapore

With cutting-edge technologies and considering airline human-resource-saving,a single pilot in commercial jets could be technically *** changes in captains’natural behaviours are initially required to comprehend the specific safe human performance envelope for safeguarding single-pilot flight,particularly in high-risk *** paper investigates how captains’performance transforms for fixing emergencies when operating from Dual-Pilot Operations(DPO)to Single-Pilot Operations(SPO)through a physiological-based *** pilots flew an emergency-included flight with/without first officers’*** neural activities and scanning behaviours were recorded using a 32-channel Electroencephalogram(EEG)and glasses-based eye tracker,with the observation and post-experiment questionnaires to evaluate the flight operations and pilots’*** alone,there was a significantly increased cortical activity in h and b waves over the frontal,parietal,and temporal lobes during the more complicated emergencies,and pilots focused less on the primary flight display while spending significantly more time scanning the other *** physiological fluctuating patterns associated with risky operations in SPO were highlighted by cross-correlating multimodal *** experimental-based noteworthy insights may wish to inform commercial SPO measures to lessen the persistent physiological fluctuation,assisting airlines in creating SPO-oriented intelligent flight systems to give captains adequate support for assuring safer air transportation.

关键词： Aviation engineering Single pilot operations Behaviour changes Eye tracker Electroencephalogram

Low-rank matrix recovery with total generalized variation for defending adversarial examples

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Frontiers of Information Technology & Electronic Engineering 2024年第3期25卷 432-445页

作者： Wen LI Hengyou WAng Lianzhi HUO Qiang HE Linlin chen Zhiquan HE Wing W.y.ng School of Science Beijing University of Civil Engineering and ArchitectureBeijing 100044China School of Computer Science and Engineering South China University of TechnologyGuangzhou 510006China Aerospace Information Research Institute Chinese Academy of SciencesBeijing 100094China Guangdong Key Laboratory of Intelligent Information Processing Shenzhen 518060China Institute of Big Data modeling and Technology Beijing University of Civil Engineering and ArchitectureBeijing 100044China

Low-rank matrix decomposition with first-order total variation(TV)regularization exhibits excellent performance in exploration of image *** advantage of its excellent performance in image denoising,we apply it to improve the robustness of deep neural ***,although TV regularization can improve the robustness of the model,it reduces the accuracy of normal samples due to its *** our work,we develop a new low-rank matrix recovery model,called LRTGV,which incorporates total generalized variation(TGV)regularization into the reweighted low-rank matrix recovery *** the proposed model,TGV is used to better reconstruct texture information without *** reweighted nuclear norm and Li-norm can enhance the global structure ***,the proposed LRTGV can destroy the structure of adversarial noise while re-enhancing the global structure and local texture of the *** solve the challenging optimal model issue,we propose an algorithm based on the alternating direction method of *** results show that the proposed algorithm has a certain defense capability against black-box attacks,and outperforms state-of-the-art low-rank matrix recovery methods in image restoration.

关键词： Total generalized variation Low-rank matrix Alternating direction method of multipliers Adversarial example

Cooperative Target Fencing of multiple Vehicles for a General Target with Connectivity Preservation and Collision Avoidance

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Journal of Systems Science & Complexity 2024年第1期37卷 136-151页

作者： PAN Zini chen Ben m Department of mechanical and Automation Engineering The Chinese University of Hong KongHong KongChina

In this paper,the authors study the cooperative target-fencing problem for n-dimensional systems and a target with a general *** using the velocity of the vehicles,a position feedback control law is proposed to fence the general target into the convex hull formed by the ***,the dynamics of each vehicle is described by a double-integrator *** potential functions are designed to guarantee connectivity preservation of the communication network and collision avoidance among the *** proposed approach can deal with a target whose trajectory is any twice continuously differentiable function of *** effectiveness of the result is verified by a numerical example.

关键词： multi-agent systems networked systems target fencing

Exponentially Convergent multiscale Finite Element method

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Communications on Applied mathematics and Computation 2024年第2期6卷 862-878页

作者： yifan chen Thomas y.Hou yixuan Wang Applied and Computational mathematics CaltechPasadena 91106USA

We provide a concise review of the exponentially convergent multiscale finite element method(ExpmsFEm)for efficient model reduction of PDEs in heterogeneous media without scale separation and in high-frequency wave *** ExpmsFEm is built on the non-overlapped domain decomposition in the classical msFEm while enriching the approximation space systematically to achieve a nearly exponential convergence rate regarding the number of basis *** most generalizations of the msFEm in the literature,the ExpmsFEm does not rely on any partition of unity *** general,it is necessary to use function representations dependent on the right-hand side to break the algebraic Kolmogorov n-width barrier to achieve exponential ***,there are online and offline parts in the function representation provided by the *** online part depends on the right-hand side locally and can be computed in parallel *** offline part contains basis functions that are used in the Galerkin method to assemble the stiffness matrix;they are all independent of the right-hand side,so the stiffness matrix can be used repeatedly in multi-query scenarios.

关键词： multiscale method Exponential convergence Helmholtz's equation Domain decomposition Nonlinear model reduction

multi-population particle swarm optimization algorithm for automatic design of steel frames

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Frontiers of Structural and Civil Engineering 2024年第1期18卷 89-103页

作者： Wenchen SHAN Jiepeng LIU yao DIng y.Frank chen Junwen ZHOU Institute of Smart City and Intelligent Transportation Southwest Jiaotong UniversityChengdu 610000China School of Civil Engineering Chongqing UniversityChongqing 400045China Department of Civil Engineering the Pennsylvania State UniversityMiddletownPA 17057USA

Steel structures are widely used;however,their traditional design method is a trial-and-error procedure which is neither efficient nor cost ***,a multi-population particle swarm optimization(mPPSO)algorithm is developed to optimize the weight of steel frames according to standard design *** are made to improve the algorithm performances including the constraint-based strategy,piecewise mean learning strategy and multi-population cooperative *** proposed method is tested against the representative frame taken from American standards and against other steel frames matching Chinese design *** related parameter influences on optimization results are *** the representative frame,mPPSO can achieve greater efficiency through reduction of the number of analyses by more than 65% and can obtain frame with the weight for at least 2.4%lighter.A similar trend can also be observed in cases subjected to Chinese design *** addition,a migration interval of 1 and the number of populations as 5 are recommended to obtain better mPPSO *** purpose of the study is to propose a method with high efficiency and robustness that is not confined to structural scales and design *** aims to provide a reference for automatic structural optimization design problems even with dimensional *** proposed method can be easily generalized to the optimization problem of other structural systems.

关键词： steel frame multi-population particle swarm optimization automatic structural optimization design

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Profile of *** chen

Science China(Life Sciences) 2024年第10期67卷 2062-2063页

作者： chen, Songlin yellow Sea Fisheries Res Inst Qingdao Peoples R China

For decades,*** has been engaged in fish germplasm preservation,sex control and research focusing on molecular breeding for disease *** discovered the first sex-specific molecular marker of fish(chen et al.,2007),deciphered the first fish genome(Chinese tongue sole)in China,revealed the sex determination mechanism in fish(chen et al.,2014),and created molecular sex control *** also discovered the molecular mechanism of metamorphosis in flatfish(Shao et al.,2017)and developed China's first fish disease-resistant breeding gene chip,“yUXIN No.1”.

关键词： technology breeding

Generation of polarized electron beams through self-injection in the interaction of a laser with a pre-polarized plasma

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High Power Laser Science and Engineering 2024年第3期12卷 62-68页

作者： L.R.yin X.F.Li y.J.Gu N.Cao Q.Kong m.Büscher S.m.Weng m.chen Z.m.Sheng Key Laboratory of Nuclear Physics and Ion-beam Application(moE) Institute of Modern PhysicsDepartment of Nuclear Science and TechnologyFudan UniversityShanghaiChina State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghaiChina SANKEN(Institute of Scientific and Industrial Research) Osaka UniversityOsakaJapan Sichuan Research Institute Shanghai Jiao Tong UniversityChengduChina Peter Grünberg Institut(PGI-6) Forschungszentrum JülichJülichGermany Institut für Laser-und Plasmaphysik Heinrich-Heine-Universität DüsseldorfDüsseldorfGermany Key Laboratory for Laser Plasmas(moE) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghaiChina Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghaiChina Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghaiChina

Polarized electron beam production via laser wakefield acceleration in pre-polarized plasma is investigated by particlein-cell *** evolution of the electron beam polarization is studied based on the Thomas±Bargmann±michel±Telegdi equation for the transverse and longitudinal self-injection,and the depolarization process is found to be influenced by the injection *** the case of transverse self-injection,as found typically in the bubble regime,the spin precession of the accelerated electrons is mainly influenced by the ***,in the case of longitudinal injection in the quasi-1D regime(for example,*** et al.,***.110,135002(2013)),the direction of electron spin oscillates in the laser *** the electrons move around the laser axis,the net influence of the laser field is nearly zero and the contribution of the wakefield can be ***,an ultra-short electron beam with polarization of 99%can be obtained using longitudinal self-injection.

关键词： laser wakefield acceleration longitudinal self-injection particle-in-cell simulation polarized electron beam

Tailored architecture of composite electrolyte for all-solid-state sodium batteries with superior rate performance and cycle life

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Nano Research 2024年第5期17卷 4171-4180页

作者： Xiang Guan Zhenhua Jian Xingan Liao Wenchao Liao yanfei Huang Dazhu chen Robert K.y.Li chen Liu Shenzhen Key Laboratory of Polymer Science and Technology Guangdong Research Center for Interfacial Engineering of Functional MaterialsCollege of Materials Science and EngineeringShenzhen UniversityShenzhen 518055China Department of materials Science and Engineering City University of Hong KongHong KongChina

Seeking for composite electrolytes reinforced all-solid-state sodium ion batteries with superior long lifespan and rate performance remains a great ***,a unique strategy to tailor the architecture of composite electrolyte via inserting polymer chains into a small quantity of sulfate sodium grafted C_(48)0H_(28)O_(32)Zr_(6)(UIOSNa)is *** intimate contact between polymer segments and UIOSNa with limited pore size facilitates the anion immobilization of sodium salts and reduction of polymer crystallinity,thereby providing rapid ion conduction and reducing the adverse effect caused by the immigration of *** tNa+grafting of-SO_(3)Na groups on fillers allows the free movement of more sodium ions to further improve and ionic ***,even with the low content of UIOSNa fillers,a high ionic conductivity of 6.62×10^(-4) S·cm^(-1) at 60℃ and a transference number of 0.67 for the special designed composite electrolyte are *** assembled all-solid-state sodium cell exhibits a remarkable rate performance for 500 cycles with 95.96%capacity retention at a high current rate of 4 *** corresponding pouch cell can stably work for 1000 cycles with 97.03%capacity retention at 1 C,which is superior to most of the reported composite electrolytes in the literature.

关键词： solid state sodium battery composite electrolyte rate performance cycle life