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A new 3D plastoelastohydrodynamic lubrication model for rough surfaces

Friction 2024年第6期12卷 1176-1193页

作者： Shengyu YOU Jinyuan TANG qiang wang State Key Laboratory of Precision Manufacturing for Extreme Service Performance Central South UniversityChangsha 410083China

Plastoelastohydrodynamic lubrication of rough surfaces(R-PEHL)is a cutting-edge area of research in interface fluid-structure coupling *** existing R-PEHL model calculates the elastic-plastic deformation of rough surface by the Love equation in a semi-infinite space smooth surface,which deviates from the actual ***,it is an innovative work to study the exact solution of elastic-plastic deformation of rough surface and its influence on the solution results of R-PEHL *** this paper,a new contact calculation model of plastoelastohydrodynamic lubrication(PEHL)with three-dimensional(3D)rough surface is proposed by integrating numerical method of EHL and finite element *** new model eliminates an original error introduced by the assumption of semi-infinite space in contact calculation,providing wide applicability and high *** the given rough surfaces and working conditions,the study reveals that:(1)the oil film pressure calculated by the new model is lower than that of the smooth surface in semi-infinite space by 200–800 MPa;(2)the Mises stress of the new model is 2.5%–26.6%higher than that of the smooth surface in semi-infinite space;(3)compared with the semi-infinite space assumption,the rough surface plastic deformation of the new model is increased by 71%–173%,and the local plastic deformation singularity may appear under the semi-infinite space assumption;(4)the plastic deformation caused by the first contact cycle on the rough surface of the new model accounts for 66.7%–92.9%of the total plastic deformation,and the plastic deformation of the semi-infinite space accounts for 50%–83.3%.This study resolves the contradiction between the smooth surface assumption and the rough surface in the existing R-PEHL model,establishing a solid logic foundation for the accurate solution of R-PEHL model.

关键词： rough surface plastoelastohydrodynamic lubrication(PEHL) asperity plastic deformation semi-infinite space

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Mechanical properties of thermal aged HTPB composite solid propellant under confining pressure

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Defence Technology（防务技术） 2022年第4期18卷 618-625页

作者： Zhe-jun wang Hong-fu qiang 206 Staff Room Xi’an Hi-Tech InstituteXi'an710025PR China

With the purpose of investigating the effects of confining pressure and aging on the mechanical properties of Hydroxyl-terminated polybutadiene(HTPB)based composite solid propellant,tensile tests of thermal accelerated aged propellant samples under room temperature and different confining pressure conditions were performed through the use of a self-made confining pressure device and conventional testing ***,the maximum tensile stressσmand the corresponding strainεm for the propellant under different test conditions were obtained and *** results indicate that confining pressure and aging can significantly affect the mechanical properties of HTPB propellant,and the coupled effects are very *** the one hand,the stressσmincreases as a whole when confining pressure becomes higher or thermal aging time ***,this stress is more sensitive to aging with increasing confining *** are almost three regions in the stress increments(σm P-σm0)/σm0and thermal aging time curves for HTPB *** maximum value of the stress increment(σm P-σm0)/σm0for the propellant is about 98%at 7.0 MPa and 170 *** the other hand,the strainεm decreases with increasing thermal aging time under the whole confining pressure ***,the variation of this strain with confining pressure is more complex at various thermal aging time,which is different from that of unaged solid propellant in previous *** addition,this strain is slightly less sensitive to aging as the confining pressure ***,there is also a critical confining pressure in this investigation,whose value is between 0.15 MPa and 4.0 *** this critical pressure,the trends of the stressσmand the corresponding strainεm all ***,there are some critical thermal aging time for the stress increment(σm P-σm0)/σm0and strain increment(εm P-εm0)/εm0of HTPB propellant in this investigation,which are about at 35,50 and 170 ***,based on the tw

关键词： Thermal accelerated aging Confining pressure Hydroxyl-terminated polybutadiene propellant Mechanical properties Strength criterion

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Increasingly important role of numerical modeling in oceanic observation design strategy: A review

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Science China Earth Sciences 2020年第11期63卷 1678-1690页

作者： Kun ZHANG Mu MU qiang wang CAS Key Laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of Sciences and Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266071China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China Department of Atmospheric and Oceanic Sciences and Institute of Atmospheric Sciences Fudan UniversityShanghai 200438China CMA-FDU Joint Laboratory of Marine Meteorology Shanghai 200438China Innovation Center of Ocean and Atmosphere System Zhuhai Fudan Innovation Research InstituteZhuhai 518057China Key Laboratory of Marine Hazards Forecasting Ministry of Natural ResourcesHohai UniversityNanjing 210098China College of Oceanography Hohai UniversityNanjing 210098China

Oceanic observation design is of considerable significance and has made remarkable progress during the past several *** study addresses the critical role of numerical modeling in oceanic observation *** a brief introduction of the characteristics of existing oceanic observation design studies,we present the advantages of the model-based observation design strategy and further review its decisive *** demonstrate the effectiveness of this strategy,the targeted observation applications using the conditional nonlinear optimal perturbation(CNOP)approach for improving the Kuroshio predictions are ***,the authors present their consideration for correcting model errors by targeted observations of sensitive model parameters and mitigating the model-dependency problem by utilizing multiple modeling *** on using observing system simulation experiments to validate the designed observations and extending the model-based observation design strategy into observing oceanic climatological mean states are also discussed.

关键词： Observation design Numerical modeling Targeted observation CNOP

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Facile Fabrication of Hyperbranched Polyacetal Quaternary Ammonium with pH-Responsive Curcumin Release for Synergistic Antibacterial Activity

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Chinese Journal of Polymer Science 2023年第4期41卷 564-573,I0008页

作者： Xing wang Ya-qiang wang De-Cheng Wu Beijing National Laboratory for Molecular Sciences State Key Laboratory of Polymer Physics&ChemistryInstitute of ChemistryChinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China Department of Biomedical Engineering Southern University of Science and TechnologyShenzhen518055China

In the current global crisis of antibiotic resistance,persuit of an effective multi-pathway collaborative approach to enhance antibacterial activity is urgently ***,a kind of hyperbranched polyacetal quaternary ammonium(Hyper-ace-QA)with efficiently antibacterial function were synthesized by a succession of efficient click *** high molecular weights can be obtained just after UV irradiation for 3 h,and the grafting ratio can be easily adjusted through controlling solvent system,molar ratio,and *** studies indicated that Hyper-ace-QA had good biocompatibility and can be used as a potential antibacterial *** importantly,after in situ encapsulation of bioactive curcumin drugs into the hyperbranched intramolecular cavities,the acid-liable acetal linkers within the hyperbranched backbone made the loading antibacterial drugs rapidly release with pH-or bacterial-responsive behaviors since many bacteria can produce acids at the infection site by the combined actions of immune response and bacterial ***,the integration of quaternary ammonium characteristics and pH-triggered curcumin release could facilitate the antibacterial activity against gram-positive Staphylococcus *** work represents a synergistic strategy on offering important guidance to rational design of multifunctional antimicrobial vehicles,which would be promising therapeutic alternatives for first aid treatment of wound infection in critical situations.

关键词： Hyperbranched polymer Acetal Quaternary ammonium pH-Responsive Antibacterial activity

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Active control of flow past an elliptic cylinder using an artificial neural network trained by deep reinforcement learning

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Applied Mathematics and Mechanics(English Edition) 2022年第12期43卷 1921-1934页

作者： Bofu wang qiang wang Quan ZHOU Yulu LIU Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China Shanghai Frontiers Science Base for Mechanoinfomatic Shanghai UniversityShanghai 200072China School of Science Shanghai Institute of TechnologyShanghai 201418China

The active control of flow past an elliptical cylinder using the deep reinforcement learning(DRL)method is *** axis ratio of the elliptical cylinderΓvaries from 1.2 to 2.0,and four angles of attackα=0°,15°,30°,and 45°are taken into consideration for a fixed Reynolds number Re=*** mass flow rates of two synthetic jets imposed on different positions of the cylinderθ1andθ2are trained to control the *** optimal jet placement that achieves the highest drag reduction is determined for each *** a low axis ratio ellipse,i.e.,Γ=1.2,the controlled results atα=0°are similar to those for a circular cylinder with control jets applied atθ1=90°andθ2=270°.It is found that either applying the jets asymmetrically or increasing the angle of attack can achieve a higher drag reduction rate,which,however,is accompanied by increased *** control jets elongate the vortex shedding,and reduce the pressure ***,the flow topology is modified at a high angle of *** an ellipse with a relatively higher axis ratio,i.e.,Γ1.6,the drag reduction is achieved for all the angles of attack *** larger the angle of attack is,the higher the drag reduction ratio *** increased fluctuation in the drag coefficient under control is encountered,regardless of the position of the control *** control jets modify the flow topology by inducing an external vortex near the wall,causing the drag *** results suggest that the DRL can learn an active control strategy for the present configuration.

关键词： drag reduction deep reinforcement learning(DRL) elliptical cylinder active control

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Source free unsupervised domain adaptation for electro-mechanical actuator fault diagnosis

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Chinese Journal of Aeronautics 2023年第4期36卷 252-267页

作者： Jianyu wang Heng ZHANG qiang MIAO College of Electrical Engineering Sichuan UniversityChengdu 610065China

A common necessity for prior unsupervised domain adaptation methods that can improve the domain adaptation in unlabeled target domain dataset is access to source domain data-set and target domain dataset ***,data privacy makes it not always possible to access source domain dataset and target domain dataset in actual industrial equipment simulta-neously,especially for aviation component like Electro-Mechanical Actuator(EMA)whose dataset are often not shareable due to the data copyright and *** address this problem,this paper proposes a source free unsupervised domain adaptation framework for EMA fault *** proposed framework is a combination of feature network and ***,source domain datasets are only applied to train a source ***,the well-trained source model is trans-ferred to target domain and classifier is frozen based on source domain ***,nearest centroid filtering is introduced to filter the reliable pseudo labels for unlabeled target domain data-set,and finally,supervised learning and pseudo label clustering are applied to fine-tune the trans-ferred *** comparison with several traditional unsupervised domain adaptation methods,case studies based on low-and high-frequency monitoring signals on EMA indicate the effectiveness of the proposed method.

关键词： Data privacy Electro-mechanical actuator Pseudo-label clustering Nearest centroid filtering Unsupervised domain adaptation

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Polymeric partners breathe together: using gas to direct polymer self-assembly via gas-bridging chemistry

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Science China Chemistry 2022年第7期65卷 1401-1410页

作者： Zehao Gong Yixin wang qiang Yan State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular ScienceFudan University200433China

The quest for a general and facile way to regulate polymer self-assembled nanostructures with low-to high-order ergodicity is an eternal theme in soft nanoparticle fabrication. Here we present an unprecedented gas-bridging strategy that allows to use gas to direct polymer self-assembly in continuous and tunable manners. Such system comprises a partner of frustrated Lewis polymers with bulky Lewis acid and base groups. They can together “breathe in” external gases to form gas-bridged structures between the two complementary moieties, which drive their mutual complexation and assemble into polymer nanoparticles of diverse geometries and dimensionalities. This strategy is applicable to a broad family of gas substances including but not limited to carbon oxides, nitrogen oxides, sulfur oxides, and even olefins;moreover, tailoring gas types and levels can dictate distinct assembling evolutionary pathways and deformable behaviors among spherical, fibrous, polymersomal, tubesomal and cubosomal morphologies. We also discover that the gas-based bonding chemistry is the mechanistic basis underlying the phase transitional control and phase window regulation. This will open a new direction of making bespoke polymer nanostructures with gas.

关键词： gas-bridging bond Lewis pair polymer dynamic covalent chemistry self-assembly tunable nanostructure

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A useful approach to sensitivity and predictability studies in geophysical fluid dynamics: conditional non-linear optimal perturbation

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National Science Review 2020年第1期7卷 214-223页

作者： qiang wang Mu Mu Guodong Sun CAS Key Laboratory of Ocean Circulation and Waves Institute of Oceanology Chinese Academy of Sciences Pilot National Laboratory for Marine Science and Technology(Qingdao) LASG Institute of Atmospheric Physics Chinese Academy of Sciences Center for Ocean Mega-Science Chinese Academy of Sciences University of Chinese Academy of Sciences Department of Atmospheric and Oceanic Sciences Institute of Atmospheric Sciences Fudan University

In atmospheric and oceanic studies, it is important to investigate the uncertainty of model solutions. The conditional non-linear optimal perturbation(CNOP) method is useful for addressing the uncertainty. This paper reviews the development of the CNOP method and its computational aspects in recent ***, the CNOP method was first proposed to investigate the effects of the optimal initial perturbation on atmosphere and ocean model results. Then, it was extended to explore the influences of the optimal parameter perturbation, model tendency perturbation and boundary condition perturbation. To obtain solutions to these optimal perturbations, four kinds of optimization approaches were developed: the adjoint-based method, the adjoint-free method, the intelligent optimization method and the unconstrained optimization method. We illustrate the calculation process of each method and its advantages and disadvantages. Then, taking the Zebiak–Cane model as an example, we compare the CNOPs related to initial conditions(CNOP-Is) calculated by the above four methods. It was found that the dominant structures of the CNOP-Is for different methods are similar, although some differences in details ***, we discuss the necessity and possible direction for designing a more effective optimization approach related to the CNOP in the future.

关键词： CNOP non-linear optimization atmosphere ocean

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Improving Fatigue Properties of 316L Stainless Steel Welded Joints by Surface Spinning Strengthening

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Acta Metallurgica Sinica(English Letters) 2024年第5期37卷 840-854页

作者： Dongqiqiong wang qiang wang Xiaowu Li Zhefeng Zhang Department of Materials Physics and Chemistry School of Materials Science and Engineeringand Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education)Northeastern UniversityShenyang 110819China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China College of Light Industry Liaoning UniversityShenyang 110036China

The surface spinning strengthening(3S)mechanism and fatigue life extension mechanism of 316L stainless steel welded joint were systematically elucidated by microstructural analyses and mechanical *** indicate that surface gradient hardening layer of approximately 1 mm is formed in the base material through grain fragmentation and deformation twin strengthening,as well as in the welding zone composed of deformedδ-phases and *** fatigue strength of welded joint after 3S significantly rises by 32%(from 190 to 250 MPa),which is attributed to the effective elimination of surface geometric defects,discrete refinement ofδ-Fe phases and the appropriate improvement in the surface strength,collectively mitigating strain localization and surface fatigue damage within the gradient strengthening *** redistributed fineδ-Fe phases benefited by strong stress transfer of 3S reduce the risk of surface weak phase cracking,causing the fatigue fracture to transition from microstructure defects to crystal defects dominated by slip,further suppressing the initiation and early propagation of fatigue cracks.

关键词： 316L stainless steel Welded joint Surface spinning strengthening Nanotwin Fatigue life

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An attention graph stacked autoencoder for anomaly detection of electro-mechanical actuator using spatio-temporal multivariate signals

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Chinese Journal of Aeronautics 2024年第9期37卷 506-520页

作者： Jianyu wang Heng ZHANG qiang MIAO College of Electrical Engineering Sichuan UniversityChengdu 610065China

Health monitoring of electro-mechanical actuator(EMA)is critical to ensure the security of *** is difficult or even impossible to collect enough labeled failure or degradation data from actual *** autoencoder based on reconstruction loss is a popular model that can carry out anomaly detection with only consideration of normal training data,while it fails to capture spatio-temporal information from multivariate time series signals of multiple monitoring *** mine the spatio-temporal information from multivariate time series signals,this paper proposes an attention graph stacked autoencoder for EMA anomaly ***,attention graph con-volution is introduced into autoencoder to convolve temporal information from neighbor features to current features based on different weight ***,stacked autoencoder is applied to mine spatial information from those new aggregated temporal ***,based on the bench-mark reconstruction loss of normal training data,different health thresholds calculated by several statistic indicators can carry out anomaly detection for new testing *** comparison with tra-ditional stacked autoencoder,the proposed model could obtain higher fault detection rate and lower false alarm rate in EMA anomaly detection experiment.

关键词： Anomaly detection Spatio-temporal informa-tion Multivariate time series signals Attention graph convolution Stacked autoencoder

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