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Regulating the Nb_(2)C nanosheets with different degrees of oxidation in water lubricated sliding toward an excellent tribological performance

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Friction 2022年第3期10卷 398-410页

作者： Hao CHENG wenjie zhao Key Laboratory of Marine Materials and Related Technologies Zhejiang Key Laboratory of Marine Materials and Protective TechnologiesNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China University of Chinese Academy of Sciences Beijing 100049China

Novel two-dimensional(2D)Nb_(2)C nanosheets were successfully prepared through a simple lultrasonic and magnetic stirring treatment from the original accordion-like *** further study their water-lubrication properties and deal with common oxidation problems,Nb_(2)C nanosheets with different oxidation degrees were prepared and achieved long-term stability in deionized *** electron microscope(SEM),transmission electron microscope(TEM),scanning probe microscope(SPM),X-ray powder diffraction(XRD),Raman,and X-ray photoelectron spectrometer(XPS)experiments were utilized to characterize the structure,morphology,and dispersion of Nb_(2)C nanosheets with different degrees of *** tribological behaviors of Nb_(2)C with different degrees of oxidation as additives for water lubrication were characterized using a UMT-3 friction testing *** wear scars formed on the 316 steel surface were measured using three-dimensional(3D)laser scanning confocal *** tribological results showed that a moderately oxidized Nb_(2)C nanosheet,which owned the composition of Nb_(2)C/Nb_(2)O5/C,displayed excellent tribological performance,with the friction coefficient(COF)decreasing by 90.3%and a decrease in the wear rate by 73.1%compared with pure *** the TEM and Raman spectra,it was shown that Nb_(2)O5 nanoparticles filled in the worn zone,and the layered Nb_(2)C and C were adsorbed into the surface of the friction pair to form a protective lubricating *** combined action resulted in an excellent lubricating performance.

关键词： MXene Nb_(2)C nanosheets oxidation degree water lubrication tribology

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Tribological and anti-corrosion performance of epoxy resin composite coatings reinforced with differently sized cubic boron nitride(CBN)particles

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Friction 2021年第1期9卷 104-118页

作者： Zhiping HUANG wenjie zhao Wenchao zhao Xiaojing CI Wentao LI Key Laboratory of Marine Materials and Related Technologies Zhejiang Key Laboratory of Marine Materials and Protective TechnologiesNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China University of Chinese Academy of Sciences Beijing 100049China

A series of high solid content(30 wt%)epoxy resin(EP)composite coatings reinforced with differently sized cubic boron nitride(CBN)particles were fabricated successfully on 304 L stainless ***(PDA)was used to improve the dispersibility of CBN particles in *** structural and morphological features of the CBN particles and the composite coatings were characterized by Raman spectroscopy,scanning electron microscopy(SEM),and transmission electron microscopy(TEM).Moreover,a UMT-3 tribometer and surface profiler were used to investigate the tribological behaviors of the as-prepared composite *** impedance spectroscopy(EIS)and Tafel analysis were used to investigate the coatings'anti-corrosion *** results demonstrated that the CBN fillers could effectively enhance the tribological and anti-corrosion properties of the EP composite *** addition,when the additive proportion of the microsized(5μm)and nanosized(550 nm)CBN particles was 1:1,the tribological property of the EP composite coatings was optimal for dry sliding,which was attributed to the load carrying capability of the microsized CBN particles and the toughening effect of the nanosized CBN ***,when the additive proportion of the microsized and nanosized CBN particles was 2:1,the tribology and corrosion resistance performance were optimal in seawater *** ascribed this to the load-carrying capacity of the microparticles,which played a more important role under the seawater lubrication condition,and the more compact structure,which improved the electrolyte barrier ability for the composite coatings.

关键词： epoxy resin cubic boron nitride size composite coating wear resistance anti-corrosion

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A Crystal-Plasticity Cyclic Constitutive Model for the Ratchetting of Polycrystalline Material Considering Dislocation Substructures

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Acta Mechanica Solida Sinica 2020年第2期33卷 268-280页

作者： Xuehong Ren Shaopu Yang Guilin Wen wenjie zhao State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China

A crystal-plasticity cyclic constitutive model of polycrystalline material considering intra-granular heterogeneous dislocation substructures,in terms of three dislocation categories:mobile dislocations,immobile dislocations in the cell interiors and in the cell walls,is proposed based on the existing microscopic and macroscopic experimental *** multiplication,annihilation,rearrangement and immobilization of dislocations on each slip system are taken as the basic evolutionary mechanism of the three dislocation categories,and the cross-slip of screw dislocations is viewed as the dynamic recovery mechanism at room *** slip resistance associated with the isotropic hardening rule results from the interactions of dislocations on the slip ***,a modified nonlinear kinematic hardening rule and a rate-dependent flow rule at the slip system level are employed to improve the predictive capability of the model for ratchetting *** predictive ability of the developed model to uniaxial and mul-tiaxial ratchetting in macroscopic scale is verified by comparing with the experimental results of polycrystalline 316L stainless *** ratchetting in intra-granular scale which is obviously dependent on the crystallographic orientation and stress levels can be reasonably predicted by the proposed model.

关键词： Ratchetting Dislocation substructures Crystal plasticity Polycrystalline materials Constitutive model

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A Cyclic Constitutive Model Based on Crystal Plasticity for Body-Centered Cubic Cyclic Softening Metals

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Acta Mechanica Solida Sinica 2024年第1期37卷 33-42页

作者： Xuehong Ren wenjie zhao Shaopu Yang Guilin Wen State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China School of Mechanical Engineering Tianjin Sino-German University of Applied SciencesTianjin 300350China State Key Laboratory of Mechanical Behavior in Traffic Engineering Structure and System Safety Shijiazhuang Tiedao UniversityShijiazhuang 050043China

Under the framework of the small deformation crystal plasticity theory,a crystal plastic cyclic constitutive model for body-centered cubic(BCC)cyclic softening polycrystalline metals is *** constitutive model introduces the isotropic softening rule that includes two different mechanisms:namely softening under monotonic deformation and softening under cyclic deformation on each slip ***,a modified Armstrong-Frederick nonlinear kinematic hardening rule is *** appropriate explicit scale transition rule is selected to extend the single crystal constitutive model to the polycrystalline constitutive *** the model is used to predict the uniaxial and multiaxial ratcheting deformation of BCC axle steel EA4T to verify the rationality of the proposed *** simulation results indicate that the newly established crystal plasticity model can not only describe the cyclic softening characteristics of BCC axle steel EA4T well,but also reasonably describe the evolution laws of uniaxial ratcheting and nonproportional multiaxial ratcheting ***,the established crystal plastic cyclic constitutive model can reasonably predict the ratcheting behavior of BCC single crystal as well.

关键词： Crystal plasticity Constitutive model Softening Ratcheting

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Achieving anti-corrosion and anti-biofouling dual-function self-healing coating by natural carrier attapulgite loading with 2-Undecylimidazoline

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Journal of Materials Science & Technology 2023年第17期148卷 222-234页

作者： Yinghao Wu Jinming Wei Xiaolu Shi wenjie zhao Key Laboratory of Marine Materials and Related Technologies Zhejiang Key Laboratory of Marine Materials and Protective TechnologiesNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China Ningbo New Material Testing and Evaluation Center Co. LtdNingbo 315048China

In the marine environment,the protective coatings face serious corrosion and biofouling problem,lim-itations,and challenges that made self-healing coatings unable to perform both anti-corrosion and anti-biofouling dual-function at the same *** we constructed the corrosion resistance and anti-biofouling self-healing coating by integrating nano-containers into the coating matrix,the 2-Undecylimidazoline(ULM)acted as a corrosion inhibitor and anti-biofouling dual-functional agent which was loaded on the natural container attapulgite(ATP).To obtain high healing efficiency,a fluidity-driven self-healing silicone oil coating was thickened by fibrous ATP to enhance its stability,which played a key role in the self-healing and long-term corrosion *** self-healing time of ULM@ATP rein-forced oil coating was 4 s at least in the air and up to 30 s in the 1 M HCl ***,the ULM@ATP can significantly enhance the corrosion resistance of the self-healing coating,with the best effect achieved when the content of ULM@ATP was 5 wt.%.The impedance modulus of ULM@ATP-2 still reached 1.62×10^(8)Ωcm^(2) after 480 immersion in 3.5 wt.%NaCl solution,which is 3 orders of magnitude high than pure Oil coating(2.17×10^(5)Ωcm^(2)).The restructure of the ATP network and the release of ULM could largely inhibit the corrosion of *** continuous open circuit potential of the compos-ite coating performed the potentially infinite self-healing *** self-healing performances of the composite coating in strong acid and base solutions exhibited high environmental *** anti-corrosion and anti-biofouling(the surface coverage of adhered chlorella decreased 96.88%)dual-function strategy of self-healing coatings could be also realized by many other porous nano-materials or function *** self-healing performances of the composite coating in strong acid and base solutions exhibited high environmental *** anti-corrosion and anti-biof

关键词： Self-healing Active corrosion resistance Anti-biofouling Attapulgite

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Time-optimal guidance for intercepting moving targets with impact-angle constraints

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Chinese Journal of Aeronautics 2022年第7期35卷 157-167页

作者： Yuan ZHENG Zheng CHEN Xueming SHAO wenjie zhao School of Aeronautics and Astronautics Zhejiang UniversityHangzhou 310027China State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou 310027China

The minimum-time path for intercepting a moving target with a prescribed impact angle is studied in the *** candidate paths from Pontryagin’s maximum principle are synthesized,so that each candidate is related to a zero of a real-valued *** is found that the real-valued functions or their first-order derivatives can be converted to polynomials of at most fourth *** a result,each candidate path can be computed within a constant time by embedding a standard polynomial solver into the typical bisection *** control strategy along the shortest candidate eventually gives rise to the time-optimal guidance ***,the developments of the paper are illustrated and verified by three numerical examples.

关键词： Dubins vehicle Guidance law Minimum-time path Optimal guidance Path planning

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Fractional-order visco-plastic constitutive model for uniaxial ratcheting behaviors

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Applied Mathematics and Mechanics(English Edition) 2019年第1期40卷 49-62页

作者： wenjie zhao Shaopu YANG Guilin WEN Xuehong REN State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University State Key Laboratory of Mechanical Behavior in Traffic Engineering Structure and System Safety Shijiazhuang Tiedao University

This paper proposes a novel unified visco-plastic constitutive model for uniaxial ratcheting behaviors. The cyclic deformation of the material presents remarkable time-dependence and history memory phenomena. The fractional(fractional-order)derivative is an efficient tool for modeling these phenomena. Therefore, we develop a cyclic fractional-order unified visco-plastic(FVP) constitutive model. Specifically, within the framework of the cyclic elasto-plastic theory, the fractional derivative is used to describe the accumulated plastic strain rate and nonlinear kinematic hardening rule based on the Ohno-Abdel-Karim model. Moreover, a new radial return method for the back stress is developed to describe the unclosed hysteresis loops of the stress-strain *** capacity of the FVP model used to predict the cyclic deformation of the SS304 stainless steel is verified through a comparison with the corresponding experimental data found in the literature(KANG, G. Z., KAN, Q. H., ZHANG, J., and SUN, Y. F. Timedependent ratcheting experiments of SS304 stainless steel. International Journal of Plasticity, 22(5), 858–894(2006)). The FVP model is shown to be successful in predicting the rate-dependent ratcheting behaviors of the SS304 stainless steel.

关键词： cyclic visco-plastic constitutive fractional derivative fractional-order uni-fied visco-plastic(FVP)model rate-dependent ratcheting

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Construction of novel g-C_(3)N_(4)/β-FeOOH Z-Scheme heterostructure photocatalyst modified with carbon quantum dots for efficient degradation of RhB

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Journal of Materials Science & Technology 2024年第14期181卷 11-19页

作者： Juhua Luo Xing Liu Jieliang Gu wenjie zhao Minming Gu Yu Xie School of Materials Science and Engineering Yancheng Institute of TechnologyYancheng 224051China Jiangsu Provincial Key Laboratory of Eco-Environmental Materials Yancheng Institute of TechnologyYancheng 224051China College of Environment and Chemical Engineering Nanchang Hangkong UniversityNanchang 330063China

The degradation of organic pollutants using semiconductor photocatalysts is a new ecological approach,but the currently available photocatalysts are not very ***,in order to obtain efficient visible-light photocatalysts,g-C_(3)N_(4)/β-FeOOH-modified carbon quantum dots(CDs)composite photocat-alysts with Z-Scheme charge transfer mechanism were successfully *** phase composition and morphology of the composite were characterized by X-ray diffraction(XRD),scanning electron mi-croscopy(SEM),transmission electron microscopy(TEM),Fourier transform infrared spectrophotometry(FT-IR),and X-ray photoelectron spectroscopy(XPS)*** to the upconversion effect of the CDs,the optical response range of the composite was effectively widened,and the optical utilization rate was *** Z-Scheme heterostructure not only improves the light trapping ability,significantly inhibits charge-carrier complexation,and realizes the spatial separation of redox sites,but also ensures that the photocatalyst maintains a suitable valence-conductivity band position and maintains the strong redox *** addition,CDs have the unique characteristics of electronic storage and transfer,which effectively enhance the quantum separation efficiency of the *** photocatalytic efficiency was measured by degrading rhodamine B(RhB)under visible *** degradation performance was the best when the weight ratio of CDs was 6%,and the RhB solution degradation rate reached 100%in 60 *** unique structure and reliable mechanism provide a way for the development of advanced photocat-alyst.

关键词： Photocatalyst Degradation Visible light g-C_(3)N_(4) Carbon quantum dots

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Object servoing of differential-drive service robots using switched control

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Journal of Control and Decision 2023年第3期10卷 314-325页

作者： Weibin Jia wenjie zhao Zhihuan Song Zhengguo Li School of Aeronautics and Astronautics Zhejiang UniversityHangzhouPeople’s Republic of China School of Control Science and Engineering Zhejiang UniversityHangzhouPeople’s Republic of China SRO Department of Institute for Infocomm Research SingaporeSingapore

Object servoing is becoming more and more important for service robots. Because of the nonholonomicconstraints of a differential-drive service robot and the possibly changed pose of amovable object, it is challenging to design an object servoing scheme for the differential-driveservice robot such that it can asymptotically park at a predefined relative pose to that of the movableobject. In this paper, a novel object servoing scheme is proposed for the differential-driveservice robots using switched control. Each relative online pose is first estimated by using featuresof the movable object, the estimated pose is an input of an object servoing friendly parkingcontroller. The linear velocity and angular speed are then determined by the proposed *** results validate the performance of the proposed object servoing scheme. Due to itslow online computational cost, the proposed scheme can be applied for the real-time tasks ofdifferential-drive service robots to movable objects.

关键词： Object servoing differential-drive service robots motion estimation parking controller asymptotic stabilisation

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Effects of steaming process on rare saponins and efficacy of Panax ginseng, Panax notoginseng and Panax quinquefolium

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Chinese Herbal Medicines 2024年第4期16卷 521-528页

作者： wenjie zhao Linlin Han Tao Li Jungjoon Lee Yuqing zhao Key Laboratory of Natural Medicines of the Changbai Mountain Ministry of EducationCollege of PharmacyYanbian UniversityYanji 133002China

The steamed Panax ginseng C. A. Mey., Panax notoginseng(Burk.) F. H. Chen, and Panax quinquefolium L. not only facilitate storage, but also increase the content of rare saponins and enhance their clinical application value. The traditional steaming process has high energy consumption, low efficiency, and lacks standardized operating procedures and unified standards. This paper retrieves the research literature on the steaming process parameters, rare saponin increments, and efficacy enhancement results of ginseng plants. By summarizing the effects of different steaming processes on rare saponins and pharmacodynamics in P. ginseng, P. notoginseng and P. quinquefolium, we explored new steaming methods and established a new quality evaluation system to provide guarantee for the effectiveness and safety of clinical medication and provide scientific basis for its rational use.

关键词： Ginseng Radix et Rhizoma Notoginseng Radix et Rhizoma Panacis Quinquefolii Radix rare saponins steaming process

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