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journal of Materials Science & Technology 2020年第7期42卷 85-96页

作者： L.W.Lan X.j.wang R.P.Guo H.j.Yang j.W.Qiao Research Center for High-Entropy Alloys College of Materials Science and EngineeringTaiyuan University of TechnologyTaiyuan030024China

The tribological properties of nitrided Ni(45)(FeCoCr)(40)(AlTi)(15)high-entropy alloys(HEAs)were investigated in air and simulated acid rain under different normal loads(5,7,10,and 12 N)at ambient *** results revealed that as-cast HEAs were only composed of FCC phase,while the volume fraction of FCC phase in the nitrided alloys was significantly ***,the hard phases of AIN,CrN,Fe4 N,and TiN phases were formed in the nitrided *** thickness of the nitriding layer was about 8.4μ*** hardness increased from 8.7 GPa in as-cast alloys to 14.5 GPa in the nitrided *** addition,under the same conditions,the friction coefficient of the nitrided alloys was higher than that of as-cast alloys,but the wear rate was generally lower than that of as-cast ***,the wear rate of the nitrided alloys was the lowest in acid rain due to the lubrication,cleaning,and cooling in the liquid *** air,dominating wear mechanisms in as-cast and nitrided alloys were abrasive,delamination,and adhesive ***,the wear mechanism of as-cast and nitrided alloys in acid rain was mainly abrasive and corrosion wears.

关键词： Abrasive wear Hardness Corrosive wear Microstructure Wear mechanism

An Implicit LU-SGS Scheme for the Spectral Volume Method on Unstructured Tetrahedral Grids

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Communications in Computational Physics 2009年第10期6卷 978-996页

作者： Takanori Haga Keisuke Sawada Z.j.wang Department of Aerospace Engineering Tohoku UniversitySendai 980-8579Japan Department of Aerospace Engineering Iowa State UniversityAmesIA 50011USA

An efficient implicit lower-upper symmetric Gauss-Seidel(LU-SGS)solution approach has been applied to a high order spectral volume(SV)method for unstructured tetrahedral *** LU-SGS solver is preconditioned by the block element matrix,and the system of equations is then solved with a LU *** compact feature of SV reconstruction facilitates the efficient solution algorithm even for high order *** developed implicit solver has shown more than an order of magnitude of speed-up relative to the Runge-Kutta explicit scheme for typical inviscid and viscous problems.A convergence to a high order solution for high Reynolds number transonic flow over a 3D wing with a one equation turbulence model is also indicated.

关键词： High-order unstructured grid spectral volume implicit method

High-Order Multidomain Spectral Difference Method for the Navier-Stokes Equations on Unstructured Hexahedral Grids

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Communications in Computational Physics 2007年第2期2卷 310-333页

作者： Yuzhi Sun Z.j.wang Yen Liu Department of Aerospace Engineering Iowa State University2271 Howe HallAmesIA 50011USA NASA Ames Research Center Mail Stop T27B-1Moffett FieldCA 94035USA

A high order multidomain spectral difference method has been developed for the three dimensional Navier-Stokes equations on unstructured hexahedral *** method is easy to implement since it involves one-dimensional operations only,and does not involve surface or volume *** reconstructions are obtained by distributing solution and flux points in a geometrically similar manner in a unit *** concepts of the Riemann solver and high-order local representations are applied to achieve conservation and high order *** this paper,accuracy studies are performed to numerically verify the order of accuracy using flow problems with analytical *** order of accuracy and spectral convergence are obtained for the propagation of an isotropic vortex and Couette *** capability of the method for both inviscid and viscous flow problems with curved boundaries is also demonstrated.

关键词： High order unstructured grids spectral difference Navier-Stokes.

The unfolded protein response signaling and retinal Müller cell metabolism

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Neural Regeneration Research 2018年第11期13卷 1861-1870页

作者： Kristen Kelly joshua j.wang Sarah X.Zhang Department of Ophthalmology and Neuroscience Program Ross Eye InstituteUniversity at BuffaloState University of New York SUNY Eye Institute State University of New YorkBuffaloNYUSA

The retina is one of the most energy demanding tissues in the body. Like most neurons in the central nervous system, retinal neurons consume high amounts of adenosine-5′-triphosphate（ATP） to generate visual signal and transmit the information to the brain. Disruptions in retinal metabolism can cause neuronal dysfunction and degeneration resulting in severe visual impairment and even blindness. The homeostasis of retinal metabolism is tightly controlled by multiple signaling pathways, such as the unfolded protein response（UPR）, and the close interactions between retinal neurons and other retinal cell types including vascular cells and Müller glia. The UPR is a highly conserved adaptive cellular response and can be triggered by many physiological stressors and pathophysiological conditions. Activation of the UPR leads to changes in glycolytic rate, ATP production, de novo serine synthesis, and the hexosamine biosynthetic pathway, which are considered critical components of Müller glia metabolism and provide metabolic support to surrounding neurons. When these pathways are disrupted, neurodegeneration occurs rapidly. In this review, we summarize recent advance in studies of the UPR in Müller glia and highlight the potential role of the UPR in retinal degeneration through regulation of Müller glia metabolism.

关键词： unfolded protein response retina Müller glia metabolism neurodegeneration X-box binding protein 1 glycolysis glucose transporter

THE SEEPAGE CHARACTERISTICS OF HETEROGENEOUS BODY WITH DIFFERENT SPREADING SOLUTION MODES AND ITS APPLICATIONS

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Acta Metallurgica Sinica(English Letters) 2007年第5期20卷 363-372页

作者： H.j. wang A.X. Wu X.S. Chen j. Zhang Civil ＆ Environment Engineering School University of Science and Technology Beijing Beijing 100083 China School of Resources and Safety Engineering Central South University Changsha 410083 China

As the dump was a typically heterogeneous body, the seepage was different with varied spreading solution modes. The phenomenon of lamination that occured in the site was simulated using three layers in an indoor experiment, and the seepage effect comparison experiment of the inside spreading solution model and the top spreading solution model have been carried out. In the inside spreading solution mode, the phreatic planar flew without infiltration and the parallel layer motion model was used to calculate the seepage coefficient and equivalent seepage coefficient of each state respectively. In the top spreading solution model, the phreatic planar flew with an even infiltration on the surface, and the vertical layer motion model was adopted to calculate the above coefficient. The results showed that the seepage coefficient of the inside model was larger than the top model in the heterogeneous body, The ratio of them was between 1.42 and 3.07. On the basis of these results, the following new technologies were discussed： installing a few small diameter mechanical pore sand piles with every lamination in the using dump; drilling some holes one-off in the unused dump. These two methods could changed the top spreading solution into the inside model, thus the seepage in the dump was improved.

关键词： heterogeneous body top spreading solution inside spreading solution sand pile drawing-injection drill

Timoshenko beam model for chiral materials

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Acta Mechanica Sinica 2018年第3期34卷 549-560页

作者： T.Y.Ma Y.N.wang L.Yuan j.S.wang Q.H.Qin Department of Mechanics Tianjin University School of Engineering Deakin University Research School of Engineering Australian National University

Natural and artificial chiral materials such as deoxyribonucleic acid （DNA）, chromatin fibers, flagellar filaments, chiral nanotubes, and chiral lattice materials widely exist. Due to the chirality of intricately helical or twisted microstructures, such materials hold great promise for use in diverse applications in smart sensors and actuators, force probes in biomedical engineering, structural elements for absorption of microwaves and elastic waves, etc. In this paper, a Timoshenko beam model for chiral materials is developed based on noncentrosymmetric micropolar elasticity theory. The governing equations and boundary conditions for a chiral beam problem are derived using the variational method and Hamilton＇s principle. The static bending and free vibration problem of a chiral beam are investigated using the proposed model. It is found that chirality can significantly affect the mechanical behavior of beams, making materials more flexible compared with nonchiral counterparts, inducing coupled twisting deformation, relatively larger deflection, and lower natural frequency. This study is helpful not only for understanding the mechanical behavior of chiral materials such as DNA and chromatin fibers and characterizing their mechanical properties, but also for the design of hierarchically structured chiral materials.

关键词： Timoshenko beam model Chiral material Chirality Deflection Microrotation

Fatigue crack initiation of magnesium alloys under elastic stress amplitudes:A review

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Frontiers of Mechanical Engineering 2019年第1期14卷 113-127页

作者： B.j.wang D.K.XU S.D.wang E.H.HAN School of Environmental and Chemical Engineering Shenyang Ligong UniversityShenyang 110159China CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The most advantageous property of magnesium(Mg)alloys is their density,which is lower compared with traditional metallic *** alloys,considered the lightest metallic structural material among others,have great potential for applications as secondary load components in the transportation and aerospace *** fatigue evaluation of Mg alloys under elastic stress amplitudes is very important in ensuring their service safety and *** their hexagonal close packed structure,the fatigue crack initiation of Mg and its alloys is closely related to the deformation mechanisms of twiuning and basal ***,for Mg alloys with shrinkage porosities and inclusions,fatigue cracks will preferentially initiate at these defects,remarkably reducing the fatigue *** this paper,some fundamental aspects about the fatigue crack initiation mechanisms of Mg alloys are reviewed,in cluding the 3 followings:1)Fatigue crack initiation of as-cast Mg alloys,2)influence of microstructure on fatigue crack initiation of wrought Mg alloys,and 3)the effect of heat treatment on fatigue initiation ***,some unresolved issues and future target on the fatigue crack initiation mechanism of Mg alloys are also described.

关键词： Mg alloys fatigue behavior microstructure crack initiation deformation mechanism

Processing, Microstructure and Mechanical Properties of Ti6Al4V Particles-Reinforced Mg Matrix Composites

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Acta Metallurgica Sinica(English Letters) 2016年第10期29卷 940-950页

作者： X.M.wang X.j.wang X.S.Hu K.Wu M.Y.Zheng School of Materials Science and Engineering Harbin Institute of Technology

Novel Ti6Al4V particles-reinforced AZ91 Mg matrix composites were successfully fabricated by stir casting method. The stirring time in semisolid condition directly affected the particle distribution and the quality of the ingots. Furthermore, the optimal speed of the heating and the liquid stirring could overcome particle settlement caused by the density difference between the matrix and the particles. Ti6Al4V particles distributed uniformly in the composites with different particle contents. The average grain size decreased with the increase in the particle contents. The Ti6A14V particles bonded pretty well with the alloy matrix. In addition, there were some interfacial reactions in the composites. There were rod-like A13Ti phases at the interface. The precipitates extended from the particle surface to the matrix, and they might improve the interfacial bonding strength. The ultimate tensile strength, yield strength and elastic modulus were enhanced as the particle contents increased, and the elongation was much better than that of the same matrix material reinforced with SiC particles. Thus, the novel composites exhibit better comprehensive mechanical properties.

关键词： Magnesium matrix composites Ti6Al4V particles Stir casting Microstructure Mechanicalproperties

Review on Hydrogen Embrittlement of Press-hardened Steels for Automotive Applications

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Acta Metallurgica Sinica(English Letters) 2023年第7期36卷 1123-1143页

作者： Z.wang Q.Lu Z.H.Cao H.Chen M.X.Huang j.F.wang General Motors China Science Lab Shanghai201206China Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong Kong999077China Key Laboratory for Advanced Materials of Ministry of Education School of Materials Science and EngineeringTsinghua UniversityBeijing100084China

Press-hardened steel(PHS)with an ultimate tensile strength(UTS)of 1500 MPa has been widely used in automotive body-in-white in the last two decades,due to its ultra-high strength and excellent formability that is achieved by hot stamping ***,the application of PHS with UTS exceeding 1500 MPa in automotive industry could be deferred due to the increased risk of hydrogen *** reduce this kind of risk,recent research efforts have been focused on various ways to optimize the microstructure of *** present review intends to summarize these efforts,to highlight present solutions to address hydrogen embrittlement,and to shed light on directions for future *** influence of microstructure on the hydrogen embrittlement of PHS has been discussed in terms of both the steel substrate and the surface *** substrate part covers the influence of martensite,carbides,inclusions,and retained austenite,while the surface part covers decarburization and oxidation,pre-coating,and trimming.

关键词： Hot stamping Press-hardened steels Coating-free Hydrogen embrittlement Fracture Al-Si coating

Construction of hybrid Z-scheme graphitic C_(3)N_(4)/reduced TiO_(2) microsphere with visible-light-driven photocatalytic activity

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journal of Materiomics 2018年第3期4卷 238-246页

作者： C.Zhou N.F.Ye X.H.Yan j.j.wang j.M.Pan D.F.wang Q.wang j.X.Zu X.N.Cheng School of Materials Science and Engineering Jiangsu UniversityZhenjiang212013JiangsuChina Institute for Advanced Materials Jiangsu UniversityZhenjiang212013JiangsuChina Institute of Green Materials and Metallurgy Jiangsu UniversityZhenjiang 212013JiangsuChina

A novel Z-scheme graphitic C_(3)N_(4)/reduced TiO_(2)microsphere(g-C_(3)N_(4)/r-TiO_(2))has been successfully synthesized by a solvothermal *** as-prepared samples with different contents of g-C_(3)N_(4)were characterized by X-ray diffraction,electron paramagnetic resonance,scanning electron microscope,UV *** reflectance and photoluminescence *** r-TiO_(2)microspheres are aggregated on the surface of g-C_(3)N_(4)sheets in the as-prepared g-C_(3)N_(4)/r-TiO_(2)*** g-C_(3)N_(4)/r-TiO_(2)catalysts show enhanced photocatalytic activity for the degradation of rhodamine B under visible light *** could be attributed to these influences of oxygen vacancy(changing the band gap of TiO_(2)),the large specific surface area(providing much more active sites for photocatalytic reaction),and the synergetic effect between g-C_(3)N_(4)and r-TiO_(2)(promoting the separation for photoinduced electron-hole pairs).Moreover,the Z-scheme carriers transfer mechanism in the photocatalytic process has been discussed through trapping experiments of active *** work demonstrates the strategies of the construction of Z-scheme carriers transfer system,the introduction of oxygen vacancy and structure designing are beneficial to design materials toward solar energy conversion like contaminant degradation.

关键词： TiO_(2) C_(3)N_(4) Oxygen vacancy Z-scheme heterojunction Photocatalytic performance