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Combined effect of WS_(2) and Ti_(3)C_(2)T_(x) MXene favors oil-based ultra-low friction on rough steel-steel interface at elevated temperatures

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Science China(Technological Sciences) 2024年第7期67卷 1991-2002页

作者： LIU yangQin chen Lei WANG yang qian LinMao Tribology Research Institute State Key Laboratory of Rail Transit Vehicle SystemSchool of Mechanical EngineeringSouthwest Jiaotong UniversityChengdu 610031China Key Laboratory of Advanced Technologies of Materials(Ministry of Education) Research Institute of Frontier ScienceSouthwest Jiaotong UniversityChengdu 610031China

The lubrication performance of liquids is severely restricted and is degraded in high-temperature environments. Stable and reliable lubrication in high temperature environments has been a long-standing goal in various industrial fields. In this study,WS_(2)and Ti_(3)C_(2)T_(x)MXene nanoflakes were used as oil-based lubricant additives to generate ultra-low friction and even superlubricity(friction coefficient of ~0.007) at elevated temperatures(400℃), which has hitherto not been achieved by both individual pristine materials, WS_(2)and Ti_(3)C_(2)T_(x)MXene. Viscosity and thermogravimetric characterization revealed improvements in the high-temperature rheological properties and thermal stability of the lubricating base oil, indicating improved loadbearing and continuous lubrication capabilities at elevated temperatures. X-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy demonstrated that the formation of an iron/titanium/tungsten-rich oxide lubricious thin film at the sliding interface reduced the interfacial shear stress, which was responsible for the observed friction and wear reductions at high contact pressures(> 1.1 GPa). Although the titanium/tungsten oxide film was gradually removed after prolonged sliding, a sufficiently thick iron oxide film maintained a low friction coefficient for at least 2 h. The improved surface quality facilitates the achievement of ultra-low friction and reduced wear. The proposed lubrication methodology has a broad utilization potential as a wear-reduction strategy across various industrial fields at elevated temperatures.

关键词： ultra-low friction high-temperature wear reduction lubricating additive tungsten disulfide MXene

Effect of annealing temperature on magnetic properties of a sintered Nd-Fe-B magnet after grain boundary diffusion with Dy_(70)Cu_(30) alloy

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Journal of Rare Earths 2024年第1期42卷 116-120,I0004页

作者： Ruipeng qian Yuxuan Ma Fugang chen Hui Sun yong Zhao Yunlong chen School of Materials Science and Engineering Jiangsu University of Science and TechnologyZhenjiang212003China School of Energy and Power Engineering Jiangsu University of Science and TechnologyZhenjiang212003China

Grain boundary diffusion process(GBDP)has been developed as an effective approach to increase the coercivity of sintered Nd-Fe-B magnets by regulating the compositions and phase distributions near grain *** work aims to explore how to select the optimum annealing temperature after *** this work GBDP was performed on a sintered Nd-Fe-B magnet using Dy_(70)Cu_(30) *** GBDP the low eutectic temperature of the grain boundary phases decreases from the initial 492 to 451℃.The magnetic property dependent on different annealing temperatures near the low eutectic temperature was *** magnetic properties,especially the squareness factor of demagnetization curve show a strong dependence on the annealing *** GBDP the optimal magnetic properties can be obtained after annealing just above the low eutectic temperature of the grain boundary *** mechanism is discussed based on the microstructure analysis.

关键词： Nd-Fe-B magnet Grain boundary diffusion Annealing Dy_(70)Cu_(30)alloy Rare earths

The homogenous growth of Co-based coordination compound on graphene nanosheet for high-performance K-organic battery and its reaction mechanism

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Rare Metals 2024年第4期43卷 1622-1634页

作者： qian-qian Peng Yi-Ting Wang Shuo Qi Yao Xiao yong Wang Shuang-qiang chen School of Environmental and Chemical Engineering Shanghai UniversityShanghai200444China School of Chemistry and Materials Engineering Wenzhou UniversityWenzhou325035China

Metal coordination compounds(MCCs)are gaining popularity for potassium-ion batteries(PIBs)owing to their tuneable structure,multiple reaction sites,low cost and unique ***,they are generally subjected to intrinsic features of the sluggish ionic diffusion coefficient,low electronic conductivity and slow ***,a new MCC material of cobalt-1,3,5-trioxy-2,4,6-triamino-benzo(Co-TB)coordination compound was synthesized and homogenously grown on the surface of graphene nanosheets(GNS),forming a Co-TB@GNS composite with enhanced electronic conductivity and flexible *** from the overall enhanced conductivity,high surface area and abundant activated K-storage sites,Co-TB@GNS electrodes have exhibited superior cycling performance with high reversible capacities(312 mAh·g^(-1)after 100 cycles at 100 mA·g^(-1),224 mAh·g^(-1)after 500 cycles at 1 A·g^(-1))and better rate performances compared with the pure Co-TB compound when served as PIB's ***,multiple in-situ measurement techniques have jointly confirmed that the organic functional groups(C=O,C=N and C=C of benzene rings)and Co^(2+)in Co-TB are the main reversible K-storage sites,including in-situ Fourier transform infrared spectroscopy(FTIR)and X-ray diffraction(XRD),and partial capacity contribution is originated from GNS by the apparent K-storage behavior in the in-situ XRD pattern,proving the possibility of K-storage for metal-organic materials.

关键词： Metal coordination compounds Potassiumion battery Cobalt coordination compound K-storage mechanism

Nonlinear generation of vector beams by using a compact nonlinear fork grating

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Photonics Research 2024年第5期12卷 1036-1043页

作者： qian yang yangFEIFEI yang HAO LI HAIGANG LIU XIANFENG chen State Key Laboratory of Advanced Optical Communication Systems and Networks School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Shanghai Research Center for Quantum Sciences Shanghai 201315China

Vectorial beams have attracted great interest due to their broad applications in optical micromanipulation,optical imaging,optical micromachining,and optical *** frequency conversion is an effective technique to expand the frequency range of the vectorial ***,the scheme of existing methods to generate vector beams of the second harmonic(SH)lacks compactness in the ***,we introduce a new way to realize the generation of vector beams of SH by using a nonlinear fork grating to solve such a *** examine the properties of generated SH vector beams by using Stokes parameters,which agree well with theoretical *** we demonstrate that linearly polarized vector beams with arbitrary topological charge can be achieved by adjusting the optical axis direction of the half-wave plate(HWP).Finally,we measure the nonlinear conversion efficiency of such a *** proposed method provides a new way to generate vector beams of SH by using a microstructure of nonlinear crystal,which may also be applied in other nonlinear processes and promote all-optical waveband applications of such vector beams.

关键词： method nonlinear Nonlinear

SwiftTheft: A Time-Efficient Model Extraction Attack Framework Against Cloud-Based Deep Neural Networks

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Chinese Journal of Electronics 2024年第1期33卷 90-100页

作者： Wenbin yang Xueluan GONG Yanjiao chen qian WANG Jianshuo DONG School of Cyber Science and Engineering Wuhan University School of Computer Science Wuhan University College of Electrical Engineering Zhejiang University

With the rise of artificial intelligence and cloud computing, machine-learning-as-a-service platforms,such as Google, Amazon, and IBM, have emerged to provide sophisticated tasks for cloud applications. These proprietary models are vulnerable to model extraction attacks due to their commercial value. In this paper, we propose a time-efficient model extraction attack framework called Swift Theft that aims to steal the functionality of cloud-based deep neural network models. We distinguish Swift Theft from the existing works with a novel distribution estimation algorithm and reference model settings, finding the most informative query samples without querying the victim model. The selected query samples can be applied to various cloud models with a one-time selection. We evaluate our proposed method through extensive experiments on three victim models and six datasets, with up to 16 models for each dataset. Compared to the existing attacks, Swift Theft increases agreement(i.e., similarity) by 8% while consuming 98% less selecting time.

关键词： Performance evaluation Cloud computing Analytical models Computational modeling Estimation Artificial neural networks Artificial intelligence

Non-cooperative Game Based Optimal Dispatch Model for Integrated Energy Systems

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 1195-1207页

作者： Jiandong Duan qian Sun chen Wu Yao yang Siyu Tu School of Electrical Engineering Xi’an University of TechnologyXi’an710056China IEEE CSEE

In order to improve the efficiency of energy utilization,the integrated energy system(IES)has *** IES typically acts as a whole system during operations,the subsystems are separated,and the interests of each system are *** this paper,considering the relationship between the various energy systems,non-cooperative game theory is used to establish the optimal dispatch *** proposed model mainly relies on the relationship between the cooperation and competition among various subsystems to obtain the maximum benefit they can ***,the basic definition is combined with the particle swarm optimization algorithm to solve the *** results show that the optimization strategy proposed in this paper can operate safely and reliably,and effectively distribute the benefits of each energy system.

关键词： Integrated energy system multi-energy complimentarily non-cooperative game theory

Pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy for activating water and urea oxidation

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Green Energy & Environment 2024年第4期9卷 684-694页

作者： Guangfu qian Wei chen Jinli chen Li yong Gan Tianqi Yu Miaojing Pan Xiaoyan Zhuo Shibin Yin Guangxi Key Laboratory of Electrochemical Energy Materials College of Chemistry and Chemical EngineeringState Key Laboratory of Processing for Non-Ferrous Metal and Featured MaterialsGuangxi University100 Daxue RoadNanning530004China Institute for Structure and Function and Department of Physics Chongqing UniversityChongqing400030China

Exploitation of oxygen evolution reaction(OER)and urea oxidation reaction(UOR)catalysts with high activity and stability at large current density is a major challenge for energy-saving H_(2) production in water ***,we use the pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy activated by NiFe_(2)O_(4)(FeNi/NiFe_(2)O_(4)@NC)for efficiently increasing the performance of water and urea *** to the tensile strain effect on FeNi/NiFe_(2)O_(4)@NC,it provides a favorable modulation on the electronic properties of the active center,thus enabling amazing OER(η_(100)=196 mV)and UOR(E_(10)=1.32 V)intrinsic ***,the carbon-coated layers can be used as armor to prevent FeNi alloy from being corroded by the electrolyte for enhancing the OER/UOR stability at large current density,showing high industrial *** work thus provides a simple way to prepare high-efficiency catalyst for activating water and urea oxidation.

关键词： Carbon-encapsulated Tensile strain Catalyst Oxygen evolution reaction Urea oxidation reaction

Revealing Al-O/Al-F reaction dynamic effects on the combustion of aluminum nanoparticles in oxygen/fluorine containing environments:A reactive molecular dynamics study meshing together experimental validation

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Defence Technology（防务技术） 2024年第4期34卷 313-327页

作者： Gang Li Chuande Zhao qian Yu Fang yang Jie chen Institute of Chemical Materials China Academy of Engineering Physics(CAEP)P.O.Box 919-311Mianyang 621900SichuanChina

Improving the energy conversion efficiency in metallic fuel(e.g.,Al)combustion is always desirable but challenging,which often involves redox reactions of aluminum(Al)with various mixed oxidizing *** instance,Al-O reaction is the most common pathway to release limited energy while Al-F reaction has received much attentions to enhance Al combustion ***,microscopic understanding of the Al-O/Al-F reaction dynamics remains unsolved,which is fundamentally necessary to further improve Al combustion *** this work,for the first time,Al-O/Al-F reaction dynamic effects on the combustion of aluminum nanoparticles(n-Al)in oxygen/fluorine containing environments have been revealed via reactive molecular dynamics(RMD)simulations meshing together combustion *** RMD simulation systems of Al core/O_(2)/HF,n-Al/O_(2)/HF,and n-Al/O_(2)/CF4 with oxygen percentage ranging from 0%to 100%have been *** n-Al combustion in mixed O_(2)/CF_4 environments have been conducted by constant volume combustion *** results show that Al-O reaction exhibits kinetic benefits while Al-F reaction owns thermodynamic benefits for n-Al *** n-Al/O_(2)/HF,Al-O reaction gives faster energy release rate than Al-F reaction(1.1 times).The optimal energy release efficiency can be achieved with suitable oxygen percentage of 10%and 50%for n-Al/O_(2)/HF and n-Al/O_(2)/CF_4,*** combustion experiments,90%of oxygen percentage can optimally enhance the peak pressure,pressurization rate and combustion ***,Al-O reaction prefers to occur on the surface regions while Al-F reaction prefers to proceed in the interior regions of n-Al,confirming the kinetic/thermodynamic benefits of Al-O/Al-F *** synergistic effect of Al-O/Al-F reaction for greatly enhancing n-Al combustion efficiency is demonstrated at atomicscale,which is beneficial for optimizing the combustion performance of metallic fuel.

关键词： Al-O/Al—F reaction Kinetic benefits Thermodynamic benefits Molecular dynamics Combustion

Experimental and numerical investigation of the impacts of rotor tip-rake on excitation forces of pump-jet propulsors

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Journal of Hydrodynamics 2024年第1期36卷 142-157页

作者： Xue-qin Ji Xiao-song Zhang chen-jun yang Xiao-qian Dong State Key Laboratory of Ocean Engineering Marine Numerical Experiment CentreSchool of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China CSSC Shanghai Marine Energy Saving Technology Co. Ltd.Shanghai200011China China Ship Scientific Research Center Shanghai Branch Shanghai200011China

The tip-clearance flow in a pump-jet propulsor exerts great impacts on the fluctuating pressures and resultant unsteady forces,which are important sources of structural vibrations and radiated noise *** blade geometry close to the tip is an important factor determining the vortex strength in the tip-clearance *** the open-water condition,the effects of raking the rotor tips on the duct-surface fluctuating pressures and the resultant unsteady forces acting on different components of the propulsor are investigated via physical model experiments and the numerical solution of Reynolds-averaged Navier-Stokes(RANS)equations coupled with the SST k-ωturbulence *** measured and simulated results of hydrodynamic pressures are consistent to each other,and the simulated flows help better understand why the fluctuating pressures change with the tip *** strong fluctuations of duct-surface pressures are caused by intensive tip separation *** duct-surface pressure fluctuations are effectively reduced by using the rake distribution near the tip towards blade back side and,for the combination of the five-bladed rotor and the seven-bladed stator,the resultant unsteady horizontal(and vertical)forces acting on the duct and stator are also reduced;while increasing rake leads to negative effect on pressure fluctuations and unsteady horizontal(and vertical)forces acting on all the components of the propulsor.

关键词： Pump-jet tip-clearance tip-rake fluctuating pressures excitation forces