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An adaptive machine learning-based optimization method in the aerodynamic analysis of a finite wing under various cruise conditions

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Theoretical & Applied Mechanics Letters 2024年第1期14卷 27-34页

作者： Zilan Zhang yu Ao Shaofan Li Grace x.Gu Department of Mechanical Engineering University of CaliforniaBerkeley 94720USA Department of Engineering Peking UniversityBeijing 100871China Department of civil and Environmental Engineering University of CaliforniaBerkeley 94720USA

conventional wing aerodynamic optimization processes can be time-consuming and imprecise due to the complexity of versatile flight *** of existing literature has considered two-dimensional infinite airfoil optimization,while three-dimensional finite wing optimizations are subject to limited study because of high computational *** we create an adaptive optimization methodology built upon digitized wing shape deformation and deep learning algorithms,which enable the rapid formulation of finite wing designs for specific aerodynamic performance demands under different cruise *** methodology unfolds in three stages:radial basis function interpolated wing generation,collection of inputs from computational fluid dynamics simulations,and deep neural network that constructs the surrogate model for the optimal wing *** has been demonstrated that the proposed methodology can significantly reduce the computational cost of numerical *** also has the potential to optimize various aerial vehicles undergoing different mission environments,loading conditions,and safety requirements.

关键词： Aerodynamic optimization computational fluid dynamics Radial basis function Finite wing Deep learning neural network

Homotopy analysis solutions for the asymmetric laminar flow in a porous channel with expanding or contracting walls

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Acta Mechanica Sinica 2011年第2期27卷 208-214页

作者： x.-H. Si L.-c. Zheng x.-x. Zhang Y. chao Applied Science School University of Science and Technology Beijing 100083 Beijing China Department of Mechanical Engineering University of Science and Technology Beijing100083 Beijing China Research Institute of chemical Defense of the EL.A 102205 Beijing China

In this paper, the asymmetric laminar flow in a porous channel with expanding or contracting walls is investigated. The governing equations are reduced to ordinary ones by using suitable similar transformations. Homotopy analysis method （HAM） is employed to obtain the expres- sions for velocity fields. Graphs are sketched for values of parameters and associated dynamic characteristics, especially the expansion ratio, are analyzed in detail.

关键词： Homotopy analysis method · Expanding or contracting wall · Asymmetric laminar flow · Porous channel · Expansion ratio

Deformation kinking and highly localized nanocrystallization in metastableβ-Ti alloys using cold forging

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Journal of Materials Science & Technology 2022年第25期120卷 53-64页

作者： Keer Li W.chen G.x.yu J.Y.Zhang S.W.xin J.x.Liu x.x.Wang J.Sun State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China Northwest Institute for Nonferrous Metal Research Xi’an 710016China Baoji Titanium Industry co. Ltd.Baoji 721014China

Deformation kinking as an uncommon plastic deformation mechanism has been reported in several materials while the relevant microstructure evolution and grain refinement behavior at a large strain remain unclear so *** this study,the issue was systematically investigated by utilizing cold forging to impose severe plastic deformation(SPD)on Ti-11 V metastableβ-Ti *** is found that the formation of kink bands experiences dislocation gliding,pre-kinking and the ripening of pre-kinks in *** kink bands are subsequently thickened through the coalescence of multiple kink bands in a manner of high *** dislocation slip is developed as a dominant deformation mechanism when deformation kinking is *** resulting grain refinement involves transverse breakdown and longitudinal splitting of dislocation walls and cells,which fragment kink bands into smallβ-*** refinement of theβ-blocks is still governed by dislocation activities,and finally nanograins with a diameter of~15 nm are produced at a large strain of ***,it is revealed that nanocrystallization is highly localized inside kink bands while the outer microstructure maintains original coarse *** localized refinement characterization is ascribed to the intrinsic soft nature of kink bands,shown as low hardness in nanoindentation *** intrinsic softening of kink bands is uncovered to originate from the inner degraded dislocation density evidenced by both experimental measurement and theoretical *** findings enrich fundamental understanding of deformation kinking,and shed some light on exploring the deformation accommodation mechanisms for metal materials at large strains.

关键词： Metastableβ-Ti alloys Deformation kinking Microstructural evolution Grain refinement Dislocations

Microstructure,oxidation behavior and tribological properties of AlcrN/cu coatings deposited by a hybrid PVD technique

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Journal of Materials Science & Technology 2022年第5期100卷 150-160页

作者： Dongsen Geng Haiqing Li Ziliang chen yu.x.xu Qimin Wang School of Electromechanical Engineering Guangdong University of TechnologyGuangzhou 510006China

Achieving high hardness and low friction at elevated temperatures for nitride-based hard coatings has substantial scientific interest and application *** this study,AlcrN/cu coatings were deposited by a hybrid PVD technique combining arc evaporation from an Al_(60)cr_(40) target and magnetron sputtering from a cu target in a mixed Ar and N_(2) *** microstructure,oxidation behavior,and tribological properties of the coatings were ***/cu coatings show a dual-phase structure of(Al,cr)N solid solution and cu metallic *** sputtering power of the cu target induces the disintegration of interlayer interfaces of the nano-multilayered geometry,accompanied by a decline in hardness from above 30 GPa to 22.7 ***,the formation of fine cuO grains on the coating surface is conducive to reducing the friction coefficient of AlcrN/cu when exposed to air at high *** AlcrN/cu coating with a sputtering power of 0.5 kW obtains a friction coefficient of 0.39±0.05 after pre-oxidation at 800℃,distinctly lower than that of AlcrN,which exhibits a friction coefficient of~*** further transformation of cuO to cubic cu(Al,cr)_(2)O_(4),which stems from the solid-state reaction of cuO,Al_(2)O_(3),and cr_(2)O_(3),would cause a rise in friction coefficient and wear *** mechanism of oxidation and tribological behavior of the AlcrN/cu coatings related to the temperature and cu content was discussed.

关键词： AlcrN/cu coatings Microstructure Oxidation Friction

QUANTITATIVE STUDY ON GALVANIc EFFEcTS DURING cAVITATION DAMAGE OF 1cr13 STAINLESS STEEL

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Acta Metallurgica Sinica(English Letters) 2003年第1期16卷 15-21页

作者： x.Bai D.B.Sun H.Y.yu x.L.Zhang corrosion and Protection center University of Science and TechnologyBeijing Beijing 100083 China

The influence of the surface galvanic effects of 1cr13 SS during cavitation damage has been investigated in Nacl solutions. The results show that the solution concentration and area ratio of bubble unacted surface to the bubble-acted surface greatly influence the cavitation damage of the alloy. The surface galvanic effects can speed up the dissolution rate of the alloy, and the mass loss per area of the alloy increases linearly with the area ratio of bubble unacted surface to the bubble acted surface of the alloy.

关键词： galvanic effect cavitation damage area ratio mass loss

Layered Machinable and Electrically conductive Ti_2Alc and Ti_3Alc_2 ceramics:a Review

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Journal of Materials Science & Technology 2010年第5期26卷 385-416页

作者： x.H. Wang Y.c. Zhou Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang110016 China

Ti2Alc and Ti3Alc2 are the most light-weight and oxidation resistant layered ternary carbides belonging to the MAx *** review highlights recent achievements on the processing,microstructure,physical,mechanical and chemical properties of these two machinable and electrically conductive ***2Alc and Ti3Alc2 display superior properties such as fracture toughness,electrical and thermal conductivities,and oxidation resistance over their binary *** paper provides a comprehensive overview of the processing-microstructure-property correlations of these two *** fields of applications for Ti2Alc and Ti3Alc2 are *** addition,we point out methods for further improving their properties in some specific applications through appropriate structural design and modification.

关键词： MAx phases Ti2Alc Ti3Alc2 Machinable ceramics

MIcROSTRUcTURE EVOLUTION AND MEcHANIcAL HARDENING OF HYPEREUTEcTOID PEARLITIc STEEL DURING cOLD ROLLING

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Acta Metallurgica Sinica(English Letters) 2007年第4期20卷 287-292页

作者： x. Zhang c.x. Wang x.M. Liu Q.N. Shi Key Laboratory of Advanced Materials of yunnan Province Kunming University of Science and Technology Kunming 650093 China Institute for Structural Materials Central Iron and Steel Research InstituteBeijing 100081 China

The microstructure evolution of different cold rolling reductions （from 0 to 81.6%） was studied by SEM （scanning electron microscopy） and TEM （transmission electron microscope）. The study showed that the orientation multiplicity of pearlitic lamellas resulted in inhomogeneous deformation of different pearlitic lamellas, and with the increase of reduction, the microstructure underwent a course of ＂homogeneity → inhomogeneity → homogeneity＂. The result of xRD （x-ray diffraction） analysis indicated that cementite did not decompose and dissolve into ferrite; the results of the mechanical property test suggested that the relationship between Rp0.2 （yield strength） and ε （true strain） was in good agreement with Hollomon relationship. With the equation Rp0.2 = 1465ε^0.18, the yield strength of the steel in different reductions could be well predicted.

关键词： cold rolling hypereutectoid pearlitic steel microstructure evolution mechanical hardening

Influence of a liquid-filled compartment structure on the incoming shaped charge jet stability

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Defence Technology（防务技术） 2021年第2期17卷 571-582页

作者： x.D.Zu Z.x.Huang Z.W.Guan x.c.Yin Y.M.Zheng School of Mechanical Engineering Nanjing University of Science and TechnologyXiaolingwei 200Nanjing 210094China School of Engineering University of LiverpoolLiverpoolL693GQUK Department of Mechanics and Engineering Science Nanjing University of Science and TechnologyNanjing 210094China

Liquid-filled compartment structure consists of a bulk steel plate with matrix blind holes which are filled with liquid and a steel front plate to seal up the liquid with rings and *** liquid-filled compartment structure can resist the shaped charge warhead *** paper presents experimental and theoretical investigations of the penetration ability of the residual shaped charge jet emerging from the liquid-filled compartment structure after the penetration process at different impact *** the basis of shock wave propagation theory,the influence of the liquid-filled compartment structure on jet stability is *** interferences of the liquid backflow caused by a reflected shock wave and a back plate on jet stability under different impact angles are also *** addition,the range of the disturbed velocity segments of the jet at different impact angles and the penetration ability of the residual jet are obtained.A theoretical model is validated against the experimental penetration depths.

关键词： compartment structure Shaped charge jet Shock wave Disturbance Stability

Optimizing surface-engineered ultra-small gold nanoparticles for highly efficient miRNA delivery to enhance osteogenic differentiation of bone mesenchymal stromal cells

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Nano Research 2017年第1期10卷 49-63页

作者： Meng yu Bo Lei chuanbo Gao Jin Yan Peter x. Ma Frontier Institute of Science and Technology Xi'an Jiaotong University Xi'an 710054 China State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong University Xi'an 710054 China State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiootong University Xi'an 710054 China Department of Biomedical Engineering University of Michigan Ann Arbor M148109-2009 USA Macromolecular Science and Engineering center University of Michigan Ann Arbor M148109-1055 USA Department of Materials Science and Engineering University of Michigan Ann Arbor M148109-1078 USA

Regulation of osteogenic differentiation of bone mesenchymal stromal cells （BMScs） plays a critical role in bone regeneration. As small non-coding RNAs, microRNAs （miRNAs） play an important role in stem cell differentiation through regulating target-mRNA expression. Unfortunately, highly efficient and safe delivery of miRNAs to BMScs to regulate their osteogenic differentiation remains challenging. conventional inorganic nanocrystals have shown increased toxicity owing to their larger size precluding renal clearance. Here, we developed novel, surface-engineered, ultra-small gold nanoparticles （USAuNPs, 〈10 nm） for use as highly efficient miR-5106-delivery systems to enable regulation of BMSc differentiation. We exploited the effects of AuNPs coated layer-by-layer with polyethylenimine （PEI） and liposomes （Lipo） to enhance miR-5106-delivery activity and subsequent BMSc differentiation capacity. The PEI- and Lipo-coated AuNPs （Au@PEI@Lipo） showed negligible cytotoxicity, good miRNA-5106-binding affinity, highly efficient delivery of miRNAs to BMScs, and long-term miRNA expression （21 days）. Additionally, compared with commercial Lipofectamine 3000 and 25 kD PEI, the optimized Au@PEI@Lipo-miR-5106 nanocomplexes significantly enhanced BMSc differentiation into osteoblast-like cells through activation of the Sox9 transcription factor. Our findings reveal a promising strategy for the rational design of ultra-small inorganic nanoparticles as highly efficient miRNA-delivery platforms for tissue regeneration and disease therapy.

关键词： ultra-small goldnanoparticles surface engineering microRNA (miRNA)delivery bone mesenchymalstromal cells osteogenic differentiation