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Active elastic metamaterials for subwavelength wave propagation control

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Acta Mechanica Sinica 2015年第3期31卷 349-363页

作者： y.y.Chen G.l.Huang Department of Mechanical and Aerospace Engineering University of Missouri

Recent research activities in elastic metamaterials demonstrate a significant potential for subwavelength wave propagation control owing to their interior loca.l. resonant mechanism. The growing technological developments in electro/magnetomechanical couplings of smart materials have introduced a controlling degree of freedom for passive elastic metamaterials. Active elastic metamaterials could a.l.w for a fine control of material physical behavior and thereby induce new functional properties that cannot be produced by passive approaches. In this paper, two types of active elastic metamaterials with shunted piezoelectric materials and electrorheological elastomers are proposed. Theoretical analyses and numerical validations of the active elastic metamaterials with deta.l.d microstructures are pre- sented for designing adaptive applications in band gap structures and extraordinary waveguides. The active elastic metamaterial could provide a new design methodology for adaptive wave filters, high signal-to-noise sensors, and structural health monitoring applications.

关键词： Active elastic metamaterials Subwavelengthwave control Adaptive metastructures Smart materials

Exact solution of the one-dimensional Klein-Gordon equation with scalar and vector linear potentials in the presence of a minimal length

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Chinese Physics B 2010年第2期19卷 43-47页

作者： y Chargui l Chetouani A Trabelsi Unit de Recherche de Physique Nuclaire et des Hautes Energies Facult des Sciences de Tunis Dpartement de Physique Thorique Institut de PhysiqueUniversit de ConstantineRoute Ain El BeyConstantineAlgeria Centre National des Sciences et Technologies Nuclaires Technopole de Sidi-Thabet 2020Tunisia

Using the momentum space representation, we solve the Klein--Gordon equation in one spatial dimension for the case of mixed scalar and vector linear potentials in the context of deformed quantum mechanics characterized by a finite minimal uncertainty in position. The expressions of bound state energies and the associated wave functions are exactly obtained.

关键词： Klein--Gordon equation linear potential minimal length exact solution

Mathematical modelling of axonal microtubule bundles under dynamic torsion

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Applied Mathematics and Mechanics(English Edition) 2018年第6期39卷 829-844页

作者： J.y.WU Hong yUAN l.y.lI MOE Key laboratory of Disaster Forecast and Control in Engineering Institute of Applied MechanicsJinan University School of Engineering University of Plymouth

Owing to its viscoelastic nature, axon exhibits a stress rate-dependent me- chanical behavior. An extended tension-shear chain model with Kelvin-Voigt viscoelas- ticity is developed to illustrate the micromechanical behavior of the axon under dynamic torsional conditions. Theoretical closed-form expressions are derived to predict the de- formation, stress transfer, and fa.l.re mechanism between microtubule （MT） and tau protein while the axon is sheared dynamica.l.. The results obtained from the present an- alytical solutions demonstrate how the MT-tau interface length, spacing between the tau proteins, and loading rate affect the mechanical properties of axon. Moreover, it is found that the MTs are more prone to rupture due to the contributions from the viscoelastic effects. Under the torsional force, the MTs are so long that the stress concentrates at the loaded end where axonal MTs will break. This MT-tau protein dynamics model can help to understand the underlying pathology and molecular mechanisms of axonal injury. Additiona.l., the emphasis of this paper is on the micromechanical behavior of axon, whereas this theoretical model can be equa.l. applica.l. to other soft or hard tissues, owning the similar fibrous structure.

关键词： torsion biocomposite diffuse axonal injury (DAI) Kelvin-Voigt viscoelas-tic model dynamic response tension-shear chain model

INTERNAl FRICTION AND ElASTIC CONSTANTS OF Pd-B-H a.l.yS

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Acta Meta.l.rgica Sinica(English letters) 1998年第1期11卷 51-55页

作者： y.l.Chen Zhejiang Univ Hangzhou China

Internal friction measurements on binary and ternary α-phase a.l.ys of Pd with hydrogen and boron have been performed with a torsion pendulum and by observing the cttenuation of ultrasonic pulses. A pronounced damping maximum of binary Pd-B a.l.ys at 220K and measuring frequencies of about 4Hz could not be esta.l.shed at a frequency of 15MH. Ternary Pd-B-H a.l.ys show an additional damping maximum besides the hydrogen Zener effect, which is interpreted in terms of a changed jump frequency of hydrogen in the neighborhood of boron atoms.

关键词： Pd-B-H alioy,internal friction,elastic constant Zener effect

Correlation between depassivation and repassivation processes determined by single particle impingement:Its crucial role in the phenomenon of critical flow velocity for erosion-corrosion

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Journal of Materials Science & Technology 2021年第30期89卷 158-166页

作者： l.l.li Z.B.Wang S.y.He y.G.Zheng CAS Key laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Department of Physics Southern University of Science and TechnologyGuangdong 518055China

The correlation between depassivation and repassivation processes,which is significant in erosioncorrosion,was quantitatively investigated by single particle impingement tests at various flow velocities and impact *** results show that both repassivation and depassivation processes are associated with the kinetic energy of solid particle,and demonstrate that the repassivation is retarded by *** phenomenon proba.l. results from the depassivation-induced microstructure *** this basis,the dependence of critical flow velocity(CFV)for erosion-corrosion on the solid particle concentration and diameter is further theoretica.l. predicted and experimenta.l. ***,the crucial role of depassivation-repassivation in CFV phenomenon is further highlighted.

关键词： Erosion-corrosion Stainless steel Depassivation-repassivation Single particle impact Passive film

Condensate Polishing System for PWR Nuclear Power Plant

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Journal of Energy and Power Engineering 2011年第10期5卷 999-1004页

作者： a.l. Wang C.y. Zhang y.Q. yang l.l. yin Shandong Electric Power Engineering Consulting Institute Co. ltd. Jinan Shandong 250013 China Jinan Power Electrical Facility Co. ltd. Jinan Shandong 250013 China State Nuclear Electric Power Planning Design ＆ Research Institute Beijing 100094 China

In this paper, operation characteristic of condensate polishing system is studied during startup, based on generator blowdown limit, given limit ion concentration in condensate during condenser leakage. Further give conclusion about condensate polishing system configuration and operation requirement： full flow condensate polishing system （CPS） is necessary to the units cooled by sea water, and it is better that one or two series put in service during normal operation other than a.l.of them in hot standby. While continuous condensate tube leakage is 256 l/h, the units cooled by fresh water will be shutdown immediately, for this level leakage, whichever condensate polishing system capacity is 50% （30%） or 100%, action level 2 will be preformed, so 50% （30%） is enough for fresh water cooled units.

关键词： Condensate polishing system water quality operation.

Advances in additively manufactured titanium a.l.ys by powder bed fusion and directed energy deposition:Microstructure,defects,and mechanical behavior

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Journal of Materials Science & Technology 2024年第16期183卷 32-62页

作者： H.y.Ma J.C.Wang P.Qin y.J.liu l.y.Chen l.Q.Wang l.C.Zhang Centre for Advanced Materials and Manufacturing School of EngineeringEdith Cowan University270 Joondalup DriveJoondalupPerthWA 6027SA School of Engineering M050The University of Western Australia35 Stirling HighwayCrawleyPerthWA 6009SA Institute of Metals College of Material Science and EngineeringChangsha University of Science&TechnologyChangsha 410004China School of Material Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China State Key laboratory of Metal Matrix Composites School of Material Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Ti and its a.l.ys have been broa.l. adopted across various industries owing to their outstanding proper-ties,such as high strength-to-weight ratio,excellent fatigue performance,exceptional corrosion resistance and so *** manufacturing(AM)is a complement to,rather than a replacement for,traditional manufacturing *** enhances flexibility in fabricating complex components and resolves machin-ing cha.l.nges,resulting in reduced lead times for custom ***,owing to distinctions among various AM technologies,Ti a.l.ys fabricated by different AM methods usua.l. present differences in mi-crostructure and defects,which can significantly influence the mechanical performance of built ***,having an in-depth knowledge of the scientific aspects of fabrication and material properties is crucial to achieving high-performance Ti a.l.ys through different AM *** article reviews the mechanical properties of Ti a.l.ys fabricated by two mainstream powder-type AM techniques:powder bed fusion(PBF)and directed energy deposition(DED).The review examines several key aspects,en-compassing phase formation,grain size and morphology,and defects,and provides an in-depth analysis of their influence on the mechanical behaviors of Ti *** review can aid researchers and engi-neers in selecting appropriate PBF or DED methods and optimizing their process parameters to fabricate high-performance Ti a.l.ys for a wide range of industrial applications.

关键词： Powder bed fusion Directed energy deposition Titanium a.l.ys Phase transformation Defects Mechanical property

First-principles calculation on the electronic structures, phonon dynamics, and electrical conductivities of Pb_(10)(PO_(4))_(6O) and Pb_(9)Cu(PO_(4))_(6O) compounds

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Journal of Materials Science & Technology 2024年第6期173卷 218-224页

作者： l.y.Hao E.G.Fu State Key laboratory of Nuclear Physics and Technology Department of Technical PhysicsSchool of PhysicsPeking UniversityBeijing 100871China

Superconducting materials with high critical temperature have the potential to revolutionize many fields,including military,electronic communications,and power ***,scientists around the world have been tirelessly working with the ultimate goal of achieving high-temperature *** 2023,a preprint by lee et *** South Korea claimed the discovery of ultra-high-temperature superconductivity with a critical temperature of up to 423 K in Cu-doped lead-apatite(lK-99)(arXiv:2307.12008,arXiv:2307.12037),which caused a worldwide sensation and ***,the electronic structures,phonon dynamics,and electrical conductivities of lK-99 and its parent compound lead-apatite have been calculated using first-principles *** results show that the lead-apatite compound and the lK-99 compound are insulator and half-metal *** flat band characteristic is consistent with previous *** electrical conductivity of the lK-99 compound shows two extreme points,and the electrical conductivity along the C-axis increases significantly after 400 *** phonon dispersion spectra of the compounds were investigated,demonstrating their dynamic instability.

关键词： Superconductivity lK-99 lead-apatite First-principles calculation

Evaluation of carbon-based nanosorbents synthesised by ethylene decomposition on stainless steel substrates as potential sequestrating materials for nickel ions in aqueous solution

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Journal of Environmental Sciences 2012年第9期24卷 1559-1568页

作者： X.J.lee l.y.lee l.P.y.Foo D.G.Hassell Department of Chemical and Environmental Engineering University of Nottingham Malaysia CampusJalan Broga43500 SemenyihSelangor Darul EhsanMalaysia.

The present work covers the preparation of carbon-based nanosorbents by ethylene decomposition on stainless steel mesh without the use of external catalyst for the treatment of water containing nickel ions （Ni2＋）. The reaction temperature was varied from 650 to 850℃, while reaction time and ethylene to nitrogen flow ratio were maintained at 30 rain and 1：1 cma/min, respectively. Results show that nanosorbents synthesised at a reaction temperature of 650℃ had the sma.l.st average diameter （75 nm）, largest BET surface area （68.95 m2/g） and least amount of impurity （0.98 wt.% Fe）. A series of batch sorption tests were performed to evaluate the effects of initial pH, initial metal concentration and contact time on Ni2~ removal by the nanosorbents. The equilibrium data fitted well to Freundlich isotherm. The kinetic data were best correlated to a pseudo second-order model indicating that the process was of chemisorption type. Further analysis by the Boyd kinetic model revealed that boundary layer diffusion was the controlling step. This primary study suggests that the prepared material with Freundiich constants compared well with those in the literature, is a promising sorbent for the sequestration of Ni2＋ in aqueous solutions.

关键词： adsorption nanosorbent nickel ions isotherms kinetics