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In-situ formation of nitrogen doped microporous carbon nanospheres derived from polystyrene as lubricant additives for anti-wear and friction reduction

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Friction 2024年第3期12卷 439-451页

作者： Yixin WANG Qi Lu Huijie XIE Shujuan LIu Qian YE Feng zhou Weimin LIu State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsSchool of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'an 710072China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

This study presents a nitrogen-doped microporous carbon nanospheres(N@MCNs)prepared by a facile polymerization–carbonization process using low-cost *** N element in situ introduces polystyrene(PS)nanospheres via emulsion polymerization of styrene with cyanuric chloride as crosslinking agent,and then carbonization obtains N@*** as-prepared carbon nanospheres possess the complete spherical structure and adjustable nitrogen amount by controlling the relative proportion of tetrachloromethane and cyanuric *** friction performance of N@MCNs as lubricating oil additives was surveyed utilizing the friction experiment of ball-disc *** results showed that N@MCNs exhibit superb reduction performance of friction and *** the addition of N@MCNs was 0.06 wt%,the friction coefficient of PAO-10 decreased from 0.188 to 0.105,and the wear volume reduced by 94.4%.The width and depth of wear marks of N@MCNs decreased by 49.2% and 94.5%,*** carrying capacity of load was rocketed from 100 to 400 N *** the analysis of the lubrication mechanism,the result manifested that the prepared N@MCNs enter clearance of the friction pair,transform the sliding friction into the mixed friction of sliding and rolling,and repair the contact surface through the repair ***,the tribochemical reaction between nanoparticles and friction pairs forms a protective film containing nitride and metal oxides,which can avert direct contact with the matrix and improve the tribological *** experiment showed that nitrogen-doped polystyrene-based carbon nanospheres prepared by in-situ doping are the promising materials for wear resistance and reducing *** preparing method can be ulteriorly expanded to multi-element co-permeable *** and boron co-doped carbon nanospheres(B,N@MCNs)were prepared by mixed carbonization of N-enriched PS and boric acid,and exhibited high load carrying capacity and good tribolog

关键词： lubricant additives hypercrosslinked polystyrene carbon nanospheres friction reduction anti-wear

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Recent progress in bio-inspired macrostructure array materials with special wettability—from surface engineering to functional applications

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International Journal of Extreme Manufacturing 2024年第1期6卷 208-256页

作者： Zhongxu Lian Jianhui zhou Wanfei Ren Faze Chen Jinkai Xu Yanling Tian Huadong Yu School of Mechanical and Aerospace Engineering Jilin UniversityChangchun 130022People’s Republic of China Ministry of Education Key Laboratory for Cross-Scale Micro and Nano Manufacturing Changchun University of Science and TechnologyChangchun 130022People’s Republic of China College of Mechanical and Electrical Engineering Changchun University of Science and TechnologyChangchun 130022People’s Republic of China School of Mechanical Engineering Tianjin UniversityTianjin 300350People’s Republic of China School of Engineering University of WarwickCoventry CV47ALUnited Kingdom

Bio-inspired macrostructure array(MAA,size:submillimeter to millimeter scale)materials with special wettability(MAAMs-SW)have attracted significant research attention due to their outstanding performance in many applications,including oil repellency,liquid/droplet manipulation,anti-icing,heat transfer,water collection,and oil–water *** this review,we focus on recent developments in the theory,design,fabrication,and application of bio-inspired *** first review the history of the basic theory of special wettability and discuss representative structures and corresponding functions of some biological surfaces,thus setting the stage for the design and fabrication of bio-inspired *** then summarize the fabrication methods of special wetting MAAs in terms of three categories:additive manufacturing,subtractive manufacturing,and formative manufacturing,as well as their diverse functional applications,providing insights into the development of these ***,the challenges and directions of future research on bio-inspired MAAMs-SW are briefy *** efforts,progress,and breakthroughs from surface engineering to functional applications elaborated herein will promote the practical application of bio-inspired MAAMs-SW.

关键词： macrostructure arrays superhydrophobic 3D printing laser droplet manipulation

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Microstructure,mechanical and fracture properties of friction stir welded 2195 Al-Li alloy joints

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Chinese Journal of Aeronautics 2024年第1期37卷 345-361页

作者： Guangda SuN Weizhao SuN Li zhou Sanfeng LuO Zili ZHANG Debo LIu Huiqiang Wu State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China Shandong Provincial Key Laboratory of Special Welding Technology Harbin Institute of Technology(Weihai)Weihai 264209China Beijing Institute of Astronautical Systems Engineering Beijing 100076China

The 8 mm-thick 2195 Al-Li alloy joints were achieved by Friction Stir Welding(FSW).The microstructural evolution,temperature-dependent mechanical properties,and fracture properties were *** T1,δ’/β’and θ’precipitates were observed in the Base Metal(BM)and the Heat Affected Zone(HAZ).Most of the precipitates,except for re-precipitated δ’/β’phases,were dissolved in the Nugget Zone(NZ).The tensile specimens that failed at cryogenic temperatures(-196℃)had the maximum ultimate Tensile Strength(uTS),and the fracture surface showed the inter-granular fracture *** to those at room temperature(25℃),the decreasing tensile properties at high temperature(180℃)were related to microstructure and strain hardening *** NZ presented the optimal fracture toughness,and the Crack Tip Opening Displacement(CTOD)was mutually dominated by microhardness and grain *** on Fatigue Crack Growth(FCG)rates indicates that the Thermal-Mechanically Affected Zone(TMAZ)exhibited the most superior fatigue resistance performance at stress intensity range below17 MPa.m1/2due to compressive residual stress and the crack closure *** fatigue fracture surfaces reveal that the crack propagation zone was characterized by the striations and secondary ***,inter-granular fracture behavior was responsible for the fastest FCG rates in the NZ.

关键词： Aluminum alloys Friction stir welding Microstructural evolution Mechanical properties Fracture mechanism

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In-situ additive manufacturing of high strength yet ductility titanium composites with gradient layered structure using N_(2)

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International Journal of Extreme Manufacturing 2024年第3期6卷 387-409页

作者： Yunmian Xiao Changhui Song Zibin Liu Linqing Liu Hanxiang zhou Di Wang Yongqiang Yang School of Mechanical and Automotive Engineering South China University of TechnologyGuangzhou 510641People’s Republic of China

It has always been challenging work to reconcile the contradiction between the strength and plasticity of titanium *** powder bed fusion(LPBF) is a convenient method to fabricate innovative composites including those inspired by gradient layered *** this work,we used LPBF to selectively prepare Ti N/Ti gradient layered structure(GLSTi)composites by using different N_(2)–Ar ratios during the LPBF *** systematically investigated the mechanisms of in-situ synthesis Ti N,high strength and ductility of GLSTi composites using microscopic analysis,TEM characterization,and tensile testing with digital image ***,a digital correspondence was established between the N_(2) concentration and the volume fraction of LPBF in-situ synthesized Ti *** results show that the GLSTi composites exhibit superior mechanical properties compared to pure titanium fabricated by LPBF under pure ***,the tensile strength of GLSTi was more than 1.5times higher than that of LPBF-formed pure titanium,reaching up to 1100 MPa,while maintaining a high elongation at fracture of 17%.GLSTi breaks the bottleneck of high strength but low ductility exhibited by conventional nanoceramic particle-strengthened titanium matrix composites,and the hetero-deformation induced strengthening effect formed by the Ti N/Ti layered structure explained its strength-plasticity balanced *** microhardness exhibits a jagged variation of the relatively low hardness of 245 HV0.2 for the pure titanium layer and a high hardness of 408 HV0.2 for the N_(2) in-situ synthesis *** study provides a new concept for the structure-performance digital customization of 3D-printed Ti-based composites.

关键词： laser powder bed fusion layered structure composites in-situ synthesis TiN strength-plasticity synergy

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C14-HSL limits the mycelial morphology of pathogen Trichosporon cells but enhances their aggregation:Mechanisms and implications

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Chinese Chemical Letters 2024年第6期35卷 398-403页

作者： Xin Lu Haoran Sun Xiaomeng Li Chunrui Li Jinfeng Wang Dandan zhou Jilin Engineering Lab for Water Pollution Control and Resources Recovery School of the EnvironmentNortheast Normal UniversityChangchun 130117China State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentNanjing UniversityNanjing 210023China

The biosecurity hazards caused by pathogenic fungus have been widely *** the long-term coexistence of eukaryotic pathogens and quorum sensing bacteria in different habitats in environments,we hypothesized that they have social interactions via signal *** this work,we firstly discovered the well-known bacterial signal molecules play an adverse role in the cell morphology and metabolism in a model pathogen Trichosporon asahii.N-Tetradecanoyl-L-homoserine lactone(C14-HSL)was discovered to increase pathogen hazards of ***,which limited mycelium by 52%,but enhanced cell aggregation by 93%.Higher fluorescence intensity of tryptophan(59%)and aromatic protein(2-fold)contents after the treatment of C14-HSL,indicating that aromatic proteins helped aggregate Trichosporon and showed *** analysis revealed that C14-HSL upregulated the shikimate pathway(above1-fold)located in downstream of tricarboxylic acid cycle,which contributed to the synthesis of more aromatic proteins and the formation of larger *** limited mycelial growth of *** attributed to the up-regulated expressions of cell cycle *** fungal transboundary response to bacterial C14-HSL was controlled by signal transduction *** study provides new insights into the co-evolution of bacterial and pathogenic fungi in microecosystems.

关键词： Bacterial C14-HSL Mycelium Cell cycle Aggregation Aromatic proteins

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Effect of dynamic loading orientation on fracture properties of surrounding rocks in twin tunnels

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 393-409页

作者： Ze Deng Zheming Zhu Lei zhou Leijun Ma Jianwei Huang Yao Zhang Key Laboratory of Deep Earth and Engineering(Ministry of Education) College of Architecture and EnvironmentSichuan UniversityChengdu610065China Failure Mechanics and Engineering Disaster Prevention Key Laboratory of Sichuan Province College of Architecture and EnvironmentSichuan UniversityChengdu610065China Institute for Disaster Management and Reconstruction Sichuan UniversityChengdu610065China

For expedited transportation,vehicular tunnels are often designed as two adjacent tunnels,which frequently experience dynamic stress waves from various orientations during blasting *** analyze the impact of dynamic loading orientation on the stability of the twin-tunnel,a split Hopkinson pressure bar(SHPB)apparatus was used to conduct a dynamic test on the twin-tunnel *** two tunnels were rotated around the specimen’s center to consider the effect of dynamic loading ***-DYNA software was used for numerical simulation to reveal the failure properties and stress wave propagation law of the twin-tunnel *** findings indicate that,for a twin-tunnel exposed to a dynamic load from different orientations,the crack initiation position appears most often at the tunnel corner,tunnel spandrel,and tunnel *** the impact direction is created by a certain angle(30°,45°,60°,120°,135°,and 150°),the fractures are produced in the middle of the line between the left tunnel corner and the right tunnel *** the impact loading angle(a)is 90°,the tunnel sustains minimal damage,and only tensile fractures form in the surrounding *** orientation of the impact load could change the stress distribution in the twin-tunnel,and major fractures are more likely to form in areas where the tensile stress is concentrated.

关键词： Twin-tunnel Dynamic load Split Hopkinson pressure bar(SHPB) Fracture mode Stress distribution Displacement field distribution

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Quantifying the agreement and accuracy characteristics of four satellite-based LuLC products for cropland classification in China

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Journal of Integrative Agriculture 2024年第1期23卷 283-297页

作者： Jie Xue Xianglin Zhang Songchao Chen Bifeng Hu Nan Wang zhou Shi Department of Land Management Zhejiang UniversityHangzhou 310058China Institute of Applied Remote Sensing and Information Technology College of Environmental and Resource SciencesZhejiang UniversityHangzhou 310058China ZJu-Hangzhou Global Scientific and Technological Innovation Center Zhejiang UniversityHangzhou 311215China Department of Land Resource Management School of Public Finance and Public AdministrationJiangxi University of Finance and EconomicsNanchang 330013China Key Laboratory of Data Science in Finance and Economics Jiangxi University of Finance and EconomicsNanchang 330013China Key Laboratory of Spectroscopy Sensing Ministry of Agriculture and Rural AffairsHangzhou 310058China

Various land use and land cover(LuLC)products have been produced over the past decade with the development of remote sensing *** the differences in LuLC classification schemes,there is a lack of research on assessing the accuracy of their application to croplands in a unified ***,this study evaluated the spatial and area accuracies of cropland classification for four commonly used global LuLC products(i.e.,MCD12Q1V6,GlobCover2009,FROM-GLC and GlobeLand30)based on the harmonised FAO criterion,and quantified the relationships between four factors(i.e.,slope,elevation,field size and crop system)and cropland classification *** validation results indicated that MCD12Q1 and GlobeLand30 performed well in cropland classification regarding spatial consistency,with overall accuracies of 94.90 and 93.52%,*** FROMGLC showed the worst performance,with an overall accuracy of 83.17%.Overlaying the cropland generated by the four global LuLC products,we found the proportions of complete agreement and disagreement were 15.51 and 44.72% for the cropland classification,*** consistency was mainly observed in the Northeast China Plain,the Huang-Huai-Hai Plain and the northern part of the Middle-lower Yangtze Plain,*** contrast,low consistency was detected primarily on the eastern edge of the northern and semiarid region,the Yunnan-Guizhou Plateau and southern *** size was the most important factor for mapping *** area accuracy,compared with China Statistical Yearbook data at the provincial scale,the accuracies of different products in descending order were:GlobeLand30,FROM-GLC,MCD12Q1,and *** cropland classification schemes mainly caused large area deviations among the four products,and they also resulted in the different ranks of spatial accuracy and area accuracy among the four *** results can provide valuable suggestions for selecting cropland products at the national or provinc

关键词： global LuLC products cropland mapping accuracy evaluation food security China

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Interpretability of Neural Networks Based on Game-theoretic Interactions

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Machine Intelligence Research 2024年第4期21卷 718-739页

作者： Huilin zhou Jie Ren Huiqi Deng Xu Cheng Jinpeng Zhang Quanshi Zhang School of Electronic Information and Electrical Engineering Shanghai Jiao Tong UniversityShanghai 200240China XLAB The Second Academy of China Aerospace Science and Industry CorporationBeijing 100854China

This paper introduces the system of game-theoretic interactions,which connects both the explanation of knowledge encoded in a deep neural networks(DNN)and the explanation of the representation power of a *** this system,we define two gametheoretic interaction indexes,namely the multi-order interaction and the multivariate *** crucially,we use these interaction indexes to explain feature representations encoded in a DNN from the following four aspects:(1)Quantifying knowledge concepts encoded by a DNN;(2)Exploring how a DNN encodes visual concepts,and extracting prototypical concepts encoded in the DNN;(3)Learning optimal baseline values for the Shapley value,and providing a unified perspective to compare fourteen different attribution methods;(4)Theoretically explaining the representation bottleneck of ***,we prove the relationship between the interaction encoded in a DNN and the representation power of a DNN(e.g.,generalization power,adversarial transferability,and adversarial robustness).In this way,game-theoretic interactions successfully bridge the gap between“the explanation of knowledge concepts encoded in a DNN”and"the explanation of the representation capacity of a DNN"as a unified explanation.

关键词： Model interpretability and transparency explainable AI game theory interaction deep learning.

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Numerical Simulation of the Mass Movement Process of the 2018 Sedongpu Glacial Debris Flow by using the Fluid-Solid Coupling Method

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Journal of Earth Science 2024年第2期35卷 583-596页

作者： Xing-Yu Long Yu-Xiang Hu Bin-Rui Gan Jia-Wen zhou State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan UniversityChengdu610065China College of Water Resource and Hydropower Sichuan UniversityChengdu610065China

In the context of global warming and intensified human activities,glacier instability in plateau regions has increased,and glacier debris flows have become active,which poses a significant threat to the lives and property of people and socioeconomic *** mass movement process of glacier debris flows is extremely complex,so this paper uses the 2018 Sedongpu glacier debris flow event on the Qinghai-Tibet Plateau as an example and applies a numerical simulation method to invert the whole process of mass *** view of the interaction between phases in the process of motion,we use the fluid-solid coupling method to describe the mass *** granular-flow model and drift-flux model are employed in FLOW3D software to study the mass movement process of glacier debris flows and explore their dynamic *** results indicate that the glacier debris flow lasted for 700 s,and the movement process was roughly divided into four stages,including initiation,scraping,surging and deposition;the depositional characteristics calculated by the fluid-solid coupling model are consistent with the actual survey results and have good reliability;strong erosion occurs during the mass movement,the clear volume amplification effect,and the first wave climbs 17.8 m across the *** fluid-solid coupling method can better simulate glacier debris flows in plateau regions,which is helpful for the study of the mechanism and dynamic characteristics of such disasters.

关键词： glacial debris flow Qinghai-Tibet Plateau fluid-solid coupling FLOW3D mass movement depositional characteristics disasters engineering geology

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A quantitative second order Sobolev regularity for (inhmogeneous) normalized p(·)-Laplace equations

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Acta Mathematica Sinica,English Series 2024年

作者： Yuqing WANG Yuan zhou Department of Mathematics Beihang University School of Mathematical Sciences Beijing Normal University

Let ? be a domain of Rnwith n ≥ 2 and p(·) be a local Lipschitz funcion in ? with 1 1 and supup(x) 0 and C ≥ 1 are independent of u. These extend the related results obtaind by Adamowicz-H?st?(IMRN, 2010) when n ...

Let ? be a domain of Rnwith n ≥ 2 and p(·) be a local Lipschitz funcion in ? with 1 uild up an interior quantitative second order Sobolev regularity for the normalized p(·)-Laplace equation-?pN(·)u = 0 in ? as well as the corresponding inhomogeneous equation-?pN(·)u =f in ? with f ∈ C0(?). In particular, given any viscosity solution u to-?pN(·)u = 0 in ?, we prove the following:(i) in dimension n = 2, for any subdomain u∈? and any β ≥ 0, one has |Du|βDu ∈ Lloc2+δ(u) with a quantitative upper bound, and moreover, the map(x1, x2) → |Du|β(ux1,-ux2) is quasiregular in u in the sense that |D[|Du|βDu]|2≤-CdetD[|Du|βDu]βDu]α.*** u.(ii) in dimension n ≥ 3, for any subdomain u∈? with infup(x) > 1 and supup(x) u ∈ Lloc2+δ(u) with a quantitative upper bound, and also with a pointwise upper bound |D2u|2≤-C∑1≤i≤j≤n[uxixjuxjxi-uxixiuxjxj] α.e. in u. Here constants δ > 0 and C ≥ 1 are independent of u. These extend the related results obtaind by Adamowicz-H?st?(IMRN, 2010) when n = 2 and β = 0.

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