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Partition method and experimental validation for impact dynamics of flexible multibody system

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Acta Mechanica Sinica 2018年第3期34卷 482-492页

作者： j.y.Wang Z.y.Liu j.Z.Hong School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong University

The impact problem of a flexible multibody system is a non-smooth, high-transient, and strong-nonlinear dynamic process with variable boundary. How to model the contact/impact process accurately and efficiently is one of the main difficulties in many engineering applications. The numerical approaches being used widely in impact analysis are mainly from two fields： multibody system dynamics （MBS） and computational solid mechanics （CSM）. Approaches based on MBS provide a more efficient yet less accurate analysis of the contact/impact problems, while approaches based on CSM are well suited for particularly high accuracy needs, yet require very high computational effort. To bridge the gap between accuracy and efficiency in the dynamic simulation of a flexible multibody system with contacts/impacts, a partition method is presented considering that the contact body is divided into two parts, an impact region and a non-impact region. The impact region is modeled using the finite element method to guarantee the local accuracy, while the non-impact region is modeled using the modal reduction approach to raise the global efficiency. A three-dimensional rod-plate impact experiment is designed and performed to validate the numerical results. The principle for how to partition the contact bodies is proposed： the maximum radius of the impact region can be estimated by an analytical method, and the modal truncation orders of the non-impact region can be estimated by the highest frequency of the signal measured. The simulation results using the presented method are in good agreement with the experimental results. It shows that this method is an effec-rive formulation considering both accuracy and efficiency. Moreover, a more complicated multibody impact problem of a crank slider mechanism is investigated to strengthen this conclusion.

关键词： Partition method Impact dynamics Experimental investigation Efficiency and accuracy Partition principle

THE EFFECTS OF NEGATIVE BIAS AND FLUX RATIO ON THE PROPERTIES OF TiN THIN FILMS FORMED By FILTERED CATHODIC ARC PLASMA TECHNIQUE

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 369-374页

作者： y.j.Zhang P.X.yan Z.G.wu W.W.Zhang j.Wang Q.j.Xue DeparunentofPhysics LanzhouUniversitryLanzhou730000China DeparunentofPhysics LanzhouUniversitryLanzhou730000China／／StateKeyLaboratoryofSolidLubricationInstituteofChemicalPhysicsTheChineseAcademyofSciencesLanzhou730000China StateKeyLaboratoryofSolidLubrication InstituteofChemicalPhysicsTheChineseAcademyofSciencesLanzhou730000China

The filtered cathodic vacuum-arc (FCVA) technique is a supplementary and alterna tive technique with respect to convendtional physical and chemical vapour deposi tion which can remove macro-particles effectively and make the deposition proces s at ambient temperature. In this work, high quality TiN thin films were deposi ted on silicon substrates at low temperature using the improved filtered cathodi c arc plasma (FCAP) technique. AFM, XRD, TEM were employed to characterize the T iN thin films. The effects of the negative substrate bias on the grain size, pre ferred crystalline orientation, surface roughness of TiN thin films were discuss ed.

关键词： TiN filtered cathodic arc plasma preferred orientation

Q Inversion and Comparison of Influential Factors among Three Methods: CFS, SR, and AA

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Communications in Computational Physics 2020年第6期28卷 356-371页

作者： yinting wu j.T.wu School of Geological and Surveying&Mapping Engineering Chang’an UniversityXi’an 710064P.R.China School of CML Engineering&Architecture Ningbo Institute of TechnologyZhejiang UniversityNingbo 315100P.R.China

The goals of this study were to examine factors influencing Q inversion and to provide references for practical *** different methods for inverting Q values with VSP data were explored,including centroid frequency shift(CFS),spectral ratio(SR),and amplitude attenuation(AA).Comparison between the CFS and the other two methods was conducted on frequency band widths and low attenuation,wavefield components,interface interference,and thin *** from several sets of VSP modeling data indicated that the CFS method is more stable and accurate for dealing with thin and high Q *** band width,especially the presence of high frequencies,influences the inversion effect of all three *** wider the band,the better the results.Q inversion from downgoing wavefield was very similar to that of the upgoing *** CFS method had fewer outliers or skip values from the full wavefield than the other two ***,the applications to Q inversion for the set of field VSP data demonstrated that the Q curves from the CFS method coincided with the geological interpretations better than the Q curves of the other ***,inverse Q filtering shifted the frequency component from 25 Hz to 35 *** results demonstrated that the Q curve is more sensitive to geological horizons than velocity.

关键词： Q inversion centroid frequency shift amplitude attenuation spectral ratio zero-offset VSP data

First-Principles Study of the Influence of Lattice Misfit on the Behavior and the Ductility Effect of Hafnium in Ni-Ni3AI System

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Acta Metallurgica Sinica(English Letters) 2014年第1期27卷 87-94页

作者： y. wu j. Guo W. Zhang X. Ma Q. Zhang j. Hou R. Huang X. Liu Institute of Molecular Engineering and Applied Chemistry Anhui University of Technology Ma'anshan 243002 China Shenyang National Laboratory for Materials Science Instituteof Metal Research Chinese Academy of SciencesShenyang 110016 China College of Physics Science and Technology Shenyang NormalUniversity Huanghe Street 253 Shengyang 110034 China School of Materials Science and Engineering Anhui Universityof Technology Ma'anshan 243002 China

Two Ni/Ni3Al-interface-contained cluster models with/without lattice misfit are studied by first-principles method to clarify the debates about the segregation behaviors of Hafnium （Hf） and explore the influence of lattice misfit on the ductility effect of Hr. It is found that though Hf prefers to substitute A1 rather than Ni in Ni3A1 phase within most of the investigated misfit range, its stronger preferring to Ni phase than NiaA1 phase makes it impossible to go into Ni3A1 phase to occupy A1 site in Ni-Ni3A1 alloys. Bond order analysis in Hf-free case shows that lattice misfit has different effects on the Griffith work of interfacial cleavage 27int/E and the maximum theoretical shear stress Zmax of Ni and Ni3A1, contributing to the existence of anomalous strength-temperature phenomena in NiaA1 alloys. However, the addition of Hf will make the 27int/E （or Zmax） of both Ni3A1 and Ni decrease （or increase） with lattice misfit, indicating that the addition of Hf may make the anomalous strength-temperature relationship in Ni3A1 region disappear locally.

关键词： Hafnium Lattice misfit Segregation Ductility

Ultrahigh strength Mg-y-Ni alloys obtained by regulating second phases

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journal of Materials Science & Technology 2020年第10期42卷 117-124页

作者： S.Z.wu X.G.Qiao M.y.Zheng School of Materials Science and Engineering Harbin Institute of TechnologyHarbin150001China

Mg-y-Ni alloys with different second phases were designed by changing y/Ni atomic ratio from 1.5 to *** microstructure and mechanical properties of as-cast and as-extruded alloys were *** as-cast Mg-y-Ni alloy with y/Ni ratio of 1.5 is composed ofα-Mg and long period stacking ordered(LPSO)*** y/Ni ratio is equal to 1,nanoscale lamellarγ’phase and eutectic Mg2Ni phase are formed in addition to LPSO *** y/Ni ratio decreases further,the amount of eutectic Mg2Ni phase increases,while the amount of LPSO phase *** extrusion,the LPSO andγ’phases are distributed along the extrusion direction,while eutectic Mg2Ni phase is broken and dispersed in the as-extruded *** phase and Mg2Ni phase in the alloys promote dynamic recrystallization(DRX)during extrusion,whileγ’phase inhibits ***,the Mg96y2Ni2(at.%)alloy with LPSO phase andγ’phase as the main second phases shows the strongest basal texture after *** tensile yield strength of the as-extruded Mg-y-Ni alloys increases first and then decreases with decreasing y/Ni *** as-extruded Mg96y2Ni2(at.%)alloy with y/Ni=1 exhibits excellent mechanical properties with tensile yield strength of 465 MPa,ultimate tensile strength of 510 MPa and elongation to failure of 7.2%,which is attributed to the synergistic effect of bulk LPSO phase and nanoscaleγ’phase.

关键词： Mg-y-Ni alloys LPSO γ’Phase Mg2Ni Mechanical properties

A Modified Multiple Matching Method Based on Equipoise Pseudomulti-Channel Filter and Huber Nor

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Communications in Computational Physics 2020年第6期28卷 498-517页

This study is aimed at improving multiple adaptive *** propose a modified pseudomulti-channel matching method based on the Huber norm,to adjust the matching differences on frequency and phase between the predicted multi-ples and original *** second-order derivative of the predicted multiples is utilized to replace the derivative of its Hilbert *** to the additional frequency term,this method can enhance the high-frequency *** introduce 180◦phase rotation of the multiple channels,which can decrease phase *** Huber norm interpolates between smooth L2 norm treatment of small residuals and robust L1 norm treatment of large *** method can eliminate the restriction of large value conditions from the L2 norm and weaken the condition of orthogonality from the L1 *** applications of the Pluto and Delft models shows that compared with pseudomulti-channel matching filter,the main frequency is increased from 36 Hz to 38 Hz,and the primary reflection wave is more *** practical application of field data verifies the effectiveness of the proposed method.

关键词： Multiple adaptive matching filter equipoise pseudomulti-channel Huber norm second-order derivative

Transparent inorganic multicolour displays enabled by zinc-based electrochromic devices

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Light(Science & Applications) 2020年第1期9卷 861-871页

作者： wu Zhang Haizeng Li William W.yu Abdulhakem y.Elezzabi Ultrafast Optics and Nanophotonics Laboratory Department of Electrical and Computer EngineeringUniversity of AlbertaEdmontonAlberta T6G 2V4Canada Department of Chemistry and Physics Louisiana State UniversityShreveportLA 71115USA

Electrochromic displays have been the subject of extensive research as a promising colour display *** current state-of-the-art inorganic multicolour electrochromic displays utilize nanocavity structures that sacrifice transparency and thus limit their diverse ***,we demonstrate a transparent inorganic multicolour display platform based on Zn-based electrochromic *** devices enable independent operation of top and bottom electrochromic electrodes,thus providing additional configuration flexibility of the devices through the utilization of dual electrochromic layers under the same or different colour ***-sodium vanadium oxide(Zn-SVO)electrochromic displays were assembled by sandwiching Zn between two SVO electrodes,and they could be reversibly switched between multiple colours(orange,amber,yellow,brown,chartreuse and green)while preserving a high optical *** Zn-SVO electrochromic displays represent the most colourful transparent inorganic-based electrochromic displays to *** addition,the Zn-SVO electrochromic displays possess an open-circuit potential(OCP)of 1.56 V,which enables a self-colouration behaviour and compelling energy retrieval *** study presents a new concept integrating high transparency and high energy efficiency for inorganic multicolour displays.

关键词： transparency enable transparent

Genetics of Gallstone Disease and Their Clinical Significance: A Narrative Review

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journal of Clinical and Translational Hepatology 2024年第3期12卷 316-326页

作者： Christopher j.Costa Minh Thu T.Nguyen Haleh Vaziri George y.wu Department of Medicine University of Connecticut Health CenterFarmingtonCTUSA Division of Gastroenterology and Hepatology University of Connecticut Health CenterFarmingtonCTUSA

Gallstone(GS)disease is common and arises from a combination of genetic and environmental *** genetic abnormalities specifically leading to cholesterol GSs are rare,there are clinically significant gene variants associated with cholesterol *** contrast,most bilirubin GSs can be attributed to genetic *** pathogenesis of cholesterol and bilirubin GSs differs *** GSs are notably influenced by genetic variants within the ABC protein superfamily,including ABCG8,ABCG5,ABCB4,and ABCB11,as well as genes from the apolipoprotein family such as ApoB100 and ApoE(especially the E3/E3 and E3/E4 variants),and members of the MUC ***,bilirubin GSs are associated with genetic variants in highly expressed hepatic genes,notably UGT1A1,ABCC2(MRP2),ABCC3(MRP3),CFTR,and MUC,alongside genetic defects linked to hemolytic anemias and conditions impacting *** genetic cases constitute a small portion of GS disease,recognizing genetic predisposition is essential for proper diagnosis,treatment,and genetic counseling.

关键词： Gallstones Cholelithiasis ATP-binding cassette transporters ABCG8 protein Human UDP-glucuronosyltransferase A1

Multiple stacking of InGaAs/GaAs(731) nanostructures

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Nano-Micro Letters 2009年第1期1卷 1-3页

作者： y.Z.Xie V.P.Kunets Z.M.Wang V.Dorogan y.I.Mazur j.wu G.j.Salamo Institute of Nanoscale Science and Engineering University of Arkansas

We studied the multilayering effects of InGaAs quantum dots(QDs) on GaAs(731), a surface lying inside of the stereographic triangle. The surfaces after stacking 16 InGaAs layers were characterized with highly non-uniformity of QD spatial distribution. The bunched step regions driven by strain accumulation are decorated by QDs, therefore GaAs(731) becomes a good candidate substrate for the growth of QD clusters. The unique optical properties of the QD clusters are revealed by photoluminescence measurements. By adjusting the coverage of InGaAs, a bamboo-like nanostructured surface was observed and the quantum dots aligned up in clusters to separate the "bamboo" into sections.

关键词： Quantum dots MBE High index surfaces Nanostructures Atomic force microscopy