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A lubrication model for bubbly oil lubrication with interfacial effect and thermal effect using the theory of multiphase mixtures

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Friction 2024年第2期12卷 271-290页

作者： Shaohua LI Xiaohui LIN Shuyun jiang School of Mechanical Engineering Southeast UniversityNanjing 211189China

Bubbly oil lubrication is a type of lubrication ***,the lubrication model of the bubbly oil has not been thoroughly *** paper aims to investigate the modelling for bubbly oil lubrication considering the interfacial effect and thermal effect,and a theoretical model is established based on the theory of multiphase *** interfacial and thermal effects on the static characteristics of a thrust bearing are analyzed.A test rig for the thrust bearing is developed to measure the static characteristics of the bearing under bubbly oil *** results show that the bearing static characteristics,*** temperature rise,film thickness,friction torque,and volume flow,increase with consideration of three interfacial effects;the bearing temperature rise increases but the film thickness,friction torque,and volume flow rate decrease with consideration of the three thermal effects;the thermal effect on the bearing static characteristics is greater than the interfacial effect.

关键词： bubbly oil lubrication theory of multiphase mixtures interfacial effect thermal effect fluid bearing

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超疏水涂层对沥青路面防冰性能的影响

建筑材料学报 2018年第2期21卷 281-285页

作者：彭超张滈徐方蒋国盛陈鹏旭张伟丽中国地质大学(武汉)工程学院湖北武汉430074 长沙理工大学道路结构与材料交通行业重点实验室(长沙) 湖南长沙410004

采用有机硅橡胶与表面改性过的微米/纳米粉末制备了超疏水涂层,研究了该涂层对于沥青路面防冰性能的影响.接触角测试结果表明,该超疏水涂层的接触角达到了160°;沥青混合料表面结冰温度试验结果表明,在同样降温条件下,相比于无涂层的沥... 详细信息

采用有机硅橡胶与表面改性过的微米/纳米粉末制备了超疏水涂层,研究了该涂层对于沥青路面防冰性能的影响.接触角测试结果表明,该超疏水涂层的接触角达到了160°;沥青混合料表面结冰温度试验结果表明,在同样降温条件下,相比于无涂层的沥青混合料试件,涂有超疏水涂层沥青混合料试件的表面水滴结冰时间延长了1.5倍;沥青混合料表面冰层黏结力试验结果表明,相比于无涂层的沥青混合料试件,涂有超疏水涂层沥青混合料试件的表面冰层黏结力在-5℃时减小了84%.

关键词：超疏水硅橡胶沥青路面防冰性能

An extended numerical model of the first exothermic peak for three dimensional printed cement-based materials

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Frontiers of Structural and Civil Engineering 2024年第1期18卷 80-88页

作者： Wei jiang Wenqian LI Xi CHEN School of Materials Science and Engineering Tongji UniversityShanghai 200092China School of Civil Engineering Tongji UniversityShanghai 200092China

The first exothermic peak of cement-based material occurs a few minutes after mixing,and the properties of three dimensional(3D)printed concrete,such as setting time,are very sensitive to *** this background,based on the classical Park cement exothermic model of hydration,we propose and construct a numerical model of the first exothermic peak,taking into account the proportions of C_(3)S,C_(3)A and quicklime in *** calculated parameters are calibrated by means of relevant published exothermic test *** is found that this developed model offers a good simulation of the first exothermic peak of hydration for C_(3)S and C_(3)A proportions from 0 to 100% of cement clinker and reflects the effect of quicklime content at 8%-10%.The unique value of this research is provision of an important computational tool for applications that are sensitive to the first exothermic peak of hydration,such as 3D printing.

关键词： 3D printed cement-based materials cement hydration the first exothermic peak liquid quick-setting agent numerical model

Experimental Study on Wire Melting Control Ability of Twin-Body Plasma Arc

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 184-194页

作者： Ruiying Zhang Fan jiang Long Xue School of Mechanical Engineering Beijing Institute of Petrochemical TechnologyBeijing 102617China Beijing Academy of Safety Engineering and Technology Beijing 102617China College of Mechanical and Energy Engineering Beijing University of TechnologyBeijing 100124China

The twin-body plasma arc has the decoupling control ability of heat transfer and mass transfer,which is beneficial to shape and property control in wire arc additive *** this paper,with the wire feeding speed as a characteristic quantity,the wire melting control ability of twin-body plasma arc was studied by adjusting the current separation ratio(under the condition of a constant total current),the wire current/main current and the position of the wire in the arc axial *** results showed that under the premise that the total current remains unchanged(100 A),as the current separation ratio increased,the middle and minimum melting amounts increased approximately synchronously under the effect of anode effect power,the first melting mass range remained constant;the maximum melting amount increased twice as fast as the middle melting amount under the effect of the wire feeding speed,and the second melting mass range was *** the wire current increased,the anode effect power and the plasma arc power were both factors causing the increase in the wire melting amount;however,when the main current increased,the plasma arc power was the only factor causing the increase in the wire melting *** average wire melting increment caused by the anode effect power was approximately 2.7 times that caused by the plasma arc *** minimum melting amount was not affected by the wire-torch distance under any current separation ratio *** the current separation ratio increased and reached a threshold,the middle melting amount remained constant with increasing wire-torch *** the current separation ratio continued to increase and reached the next threshold,the maximum melting amount remained constant with the increasing wire-torch *** effect of the wire-torch distance on the wire melting amount reduced with the increase in the current separation *** this study,the decoupling mechanism and ability of this innovative

关键词： Twin-body plasma arc Melting control ability Melting amount Current separation ratio

Adaptive fault-tolerant control for non-minimum phase hypersonic vehicles based on adaptive dynamic programming

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Chinese Journal of Aeronautics 2024年第3期37卷 290-311页

作者： Le WANG Ruiyun QI Bin jiang State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China

In this paper,a novel adaptive Fault-Tolerant Control(FTC)strategy is proposed for non-minimum phase Hypersonic Vehicles(HSVs)that are affected by actuator faults and parameter *** strategy is based on the output redefinition method and Adaptive Dynamic Programming(ADP).The intelligent FTC scheme consists of two main parts:a basic fault-tolerant and stable controller and an ADP-based supplementary *** the basic FTC part,an output redefinition approach is designed to make zero-dynamics stable with respect to the new ***,Ideal Internal Dynamic(IID)is obtained using an optimal bounded inversion approach,and a tracking controller is designed for the new output to realize output tracking of the nonminimum phase HSV *** the ADP-based compensation control part,an ActionDependent Heuristic Dynamic Programming(ADHDP)adopting an actor-critic learning structure is utilized to further optimize the tracking performance of the HSV control ***,simulation results are provided to verify the effectiveness and efficiency of the proposed FTC algorithm.

关键词： Hypersonic vehicle Fault-tolerant control Non-minimum phase system Adaptive control Nonlinear control Adaptive dynamic programming

AFM probe with the U-shaped cross-sectional cantilever for measuring the ultra-low coefficient of friction of 10^(–6)

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Friction 2024年第8期12卷 1707-1715,F0004页

作者： Yushan CHEN Liang jiang Linmao QIAN Tribology Research Institute State Key Laboratory of Traction PowerSouthwest Jiaotong UniversityChengdu 610031China

Accurately measuring the coefficient of friction(COF)is the fundamental prerequisite of superlubricity *** study aimed to reduce the COF measurement resolutionΔμof atomic force microscopy(AFM).Based on the theoretical model,a distinctive strategy was adopted to reduceΔμby optimizing the cantilever’s cross-section of the AFM probe,inspired by civil engineering.Δμcan be reduced by decreasing the width of the horizontal side wR and the wall thickness t and increasing the width of the vertical side ***,the I-shape demonstrates the highest reduction inΔμ,followed by the *** the processability,the AFM probe with the U-shaped cross-sectional cantilever was investigated further,and the dimensions are 35μm wR,3.5μm wH,0.5μm t,50μm l(cantilever length),and 23μm htip(tip height).The finite element analysis results confirm its *** being fabricated and calibrated,the AFM probe achieves the minimalΔμof 1.9×10^(–6)under the maximum normal force so ***,the friction detection capability of the fabricated AFM probe improves by 78 times compared to the commercial tipless-force modulation mode(TL-FM)AFM probe with the conventional solid rectangular cross-sectional *** study provides a powerful tool for measuring 10^(–6)COF.

关键词： atomic force microscopy superlubricity coefficient of friction probe cantilever

AFM probe for measuring~10^(−5)ultra-low friction coefficient:Design and application

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Friction 2024年第1期12卷 64-73页

作者： Yushan CHEN Liang jiang Linmao QIAN Tribology Research Institute State Key Laboratory of Traction PowerSouthwest Jiaotong UniversityChengdu 610031China

Superlubricity provides a novel approach to addressing friction and wear issues in mechanical ***,little is known regarding improving the atomic force microscope(AFM)friction coefficient measurement ***,this study established the theoretical formula for the AFM friction coefficient measurement and deduced the measurement ***,the formula was applied to the AFM probe with a rectangular cross-section *** measurement resolution is associated with the dimensional properties of the AFM probe,the mechanical properties of the cantilever material,the properties of the position-sensitive detector(PSD),and probably the anti-vibration performance of the *** is feasible to make the cantilever as short as possible and the tip as high as possible to improve the measurement *** AFM probe for measuring an ultra-low friction coefficient was designed and *** cantilever’s length,width,and thickness are 50,35,and 0.6μm,*** tip height is 23μ*** measurement resolution can reach 7.1×10^(−6) under the maximum normal ***,the AFM probe was applied to measure the superlubricity between graphene *** friction coefficient is 0.00139 under 853.08 *** work provides a promising method for measuring a~10^(−5) friction coefficient of superlubricity.

关键词： atomic force microscope(AFM) superlubricity friction coefficientμ probe

Bionic functional membranes for separation of oil-in-water emulsions

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Friction 2024年第9期12卷 1909-1928页

作者： Chaolang CHEN Ruisong jiang Zhiguang GUO School of Mechanical Engineering Sichuan UniversityChengdu 610065China School of Materials Science and Engineering Hubei UniversityWuhan 430062China

The separation of oil-in-water emulsion is an urgent challenge because its massive production and discharge from daily and industrial activities have caused severe hazards to the ecosystem and serious threats to human *** technology is considered an outstanding solution strategy for the separation of oil-in-water emulsions due to its unique advantages of low cost,high efficiency,easy operation,and environmental ***,the membrane is easily fouled by the emulsion oil droplets during the separation process,causing a sharp decline in permeation flux,which greatly inhibits the long-term use of the membrane and largely shortens the membrane’s ***,it was found that endowing the membranes with special wettability e.g.,superhydrophilic and superoleophobic can greatly enhance the permeability of the continuous water phase and inhibit the adhesion of oil droplets,thus promoting the separation performance and anti-oil-fouling property of membrane for oily *** this paper,we review and discuss the recent developments in membranes with special wettability for separating oil-in-water emulsions,including the mechanism analysis of emulsion separation membrane,membrane fouling issues,design strategies,and representative studies for enhancing the membrane’s anti-oil-fouling ability and emulsion separation performance.

关键词： bionic surface membranes wettability oil-in-water emulsions oil-water separation

Controllable chemical redox reactions to couple microbial degradation for organic contaminated sites remediation:A review

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Journal of Environmental Sciences 2024年第5期139卷 428-445页

作者： Bin Chen jiang Xu Lizhong Zhu College of Environmental and Resource Sciences Zhejiang UniversityHangzhou 310058China Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control Zhejiang UniversityHangzhou 310058China Zhejiang Agriculture&Forest University Lin'an 311300China

Global environmental concern over organic contaminated sites has been progressively conspicuous during the process of urbanization and industrial *** traditional physical or chemical remediation technologies may significantly destroy the soil structure and function,coupling moderate chemical degradation with microbial remediation becomes a potential way for the green,economic,and efficient remediation of contaminated ***,this work systematically elucidates why and how to couple chemical technology with microbial remediation,mainly focused on the controllable redox reactions of organic *** rational design of materials structure,selective generation of reactive oxygen species,and estimation of degradation pathway are described for chemical ***,current progress on efficient and selective reductions of organic contaminants(i.e.,dechlorination,defluorination,-NO_(2) reduction)is *** with the microbial remediation of contaminated sites,several consideration factors of how to couple chemical and microbial remediation are proposed based on both fundamental and practical points of *** review will advance the understanding and development of chemical-microbial coupled remediation for organic contaminated sites.

关键词： Soil remediation Groundwater remediation Rational design Reactive species Environmental nanotechnology