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Progress in Natural Science:Materials International 2022年第6期32卷 758-768页

作者： H.S.Ren y.L.Shang X.y.Ren y.J.Jing H.P.Xiong y.y.Cheng Welding and Plastic Forming Division Beijing Institute of Aeronautical Materials

A novel Ti-Ni-Nb-Zr quaternary filler alloy with the composition of Ti-(19～25)Ni-(15～25)(Nb+Zr)(wt.%) was *** filler alloy was composed of(Ti,Nb)ss,(Ti,Zr,Nb)ss+(Ti,Zr)2Ni,α-Ti and Ti2Ni *** was fabricated into filler foil with a thickness of about 45 μm by a rapid solidification *** results indicate that the liquidus temperature of the Ti-Ni-Nb-Zr brazing alloy was about 978℃,and the brazing alloy presented excellent wettability on TiAl *** TiAl joint mainly consisted of β/B2 phase,Ti2Al,Ti2AlNi and α2-Ti3Al *** diffusion of Al atom from base metal to brazed seam led to the formation of Ti2Al and *** that no previously references on XRD pattern of Ti2AlNi compound can be found,Ti2AlNi cast alloy specimen was specially prepared and XRD peaks were specially *** micro-hardness and bending strength tests of the Ti2AlNi phase were carried out,and the results were 761 HV and 192 MPa,*** brazing parameters of 1010 ℃/10 min offered the joint shear strength of 280 MPa at room temperature,and the joints exhibited tensile strength of 372 MPa at room temperature and 340 MPa at 750 ℃,indicating that the newly developed filler alloy could offer a stable high-temperature strength.

关键词： TiAl Brazing Filler alloy Microstructure Mechanical properties

Reduction of structural response to near fault earthquakes by seismic isolation columns and variable friction dampers

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Earthquake Engineering and Engineering Vibration 2010年第1期9卷 113-122页

作者： y.Ribakov Department of Civil Engineering Ariel University Center of Samaria

This paper focuses on the investigation of a hybrid seismic isolation system with passive variable friction dampers for protection of structures against near fault earthquakes. The seismic isolation can be implemented by replacing the conventional columns fixed to the foundations by seismic isolating ones. These columns allow horizontal displacement between the superstructure and the foundations and decouple the building from the damaging earthquake motion. As a result, the forces in the structural elements decrease and damage that may be caused to the building by the earthquake significantly decreases. However, this positive effect is achieved on account of displacements occurring in the isolating columns. These displacements become very large when the structure is subjected to a strong earthquake. In this case, impact may occur between the parts of the isolating column yielding their damage or collapse. In order to limit the displacements in the isolating columns, it is proposed to add variable friction dampers. A method for selecting the dampers＇ properties is proposed. It is carried out using an artificial ground motion record and optimal active control algorithm. Numerical simulation of a sevenstory structure shows that the proposed method allows efficient reduction in structural response and limits the displacements at the seismic isolating columns.

关键词： seismic isolating columns variable friction dampers hybrid seismic isolation near fault earthquakes control algorithm

The first order phase-transition of polycrystal solid surfaces with nanothickness

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Rare Metals 2006年第6期25卷 709-714页

作者： y.A. Minaev Moscow State Steel & Alloys Institute and Russian Academy of Natural Science Leninsky prt.4 Moscow 119049 Russia

The fundamental equations of thermodynamics of a film have been used for describing a fundamental property of solid crystalline materials i.e. the first-order phase transition on the grain boundaries by the formation of two-dimensional liquid. The generalized equation that is obtained is used for calculating the premelting temperature of any metal, which has a value in the range of 0.55-0.86 of the melting point. The experimental diffusion coefficient of nitrogen in steel at premelting temperature is the same as in the liquid phase. The described phenomenon of phase transition on the grain boundaries decreases in case of radical modification of the existing process engineering of handling metals. It also provides a precise physical explanation to the super plasticity of fine-structure metal alloys.

关键词： thermodynamics of premelting nitrogen diffusion nitrided coatings structure high-temperature superplasticity

Modeling the interaction of nitrate anions with ozone and atmospheric moisture

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Chinese Physics B 2015年第10期24卷 160-165页

作者： A.y.Galashev Institute of High Temperature Electrochemistry Ural BranchRussian Academy of Sciences

The molecular dynamics method is used to investigate the interaction between one-six nitrate anions and water clusters absorbing six ozone molecules. The infrared（IR） absorption and reflection spectra are reshaped significantly, and new peaks appear at Raman spectra due to the addition of ozone and nitrate anions to the disperse water system. After ozone and nitrate anions are captured, the average（in frequency） IR reflection coefficient of the water disperse system increased drastically and the absorption coefficient fell.

关键词： nitrate ion ozone water cluster infrared and Raman spectra

FROM CRySTALLINE BLOCK SLIPS TO DOMINANCE OF NETWORK STRETCHING——MECHANISMS OF TENSILE DEFORMATION IN SEMI-CRySTALLINE POLyMERS

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Chinese Journal of Polymer Science 2002年第2期20卷 160-170页

作者： y. Men Fakultaet Fuer Physik Albert-Ludwigs-Universitaet Freiburg 79104

The mechanism of tensile deformation in semi-crystalline polymers was studied based on true stress-strain curvesobtained with the aid of a video-controlled tensile set-up. The deformation is affected by both the crystalline and theamorphous phases. However, the relative weights of the two portions change with the deformation stage. At lowdeformations the coupling and coarse slips of the crystalline blocks dominate the mechanical properties, which allows thesystem to maintain a homogeneous strain distribution in the sample. As the stretching increases, at a critical strain the forcegenerated from entangled fluid portions reaches a critical value to destroy the crystallites. The dominant deformationmechanism then changes into a disaggregation - recrystallization process.

关键词： Semi-crystalline polymer Deformation mechanism Network Mechanical property

A G^E/Equation of State Mixing Rule for Vapor-Liquid Equilibria

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Chinese Journal of Chemical Engineering 1998年第3期6卷 14-28页

作者：屈一新汪文川 Lee y.y. Chung K.y. Lee y.W. Korea Institute of Science and Technology SeoulKorea

A new excess Gibbs free energy/equation of state type mixing 0rule was derived byremoving the infinite pressure boundary condition imposed by Wong and *** mixing rulewas extensively tested in terms of a comprehensive data base,consisting of 52 simple nonpolar-nonpolar,carbon dioxide containing,hydrocarbon-hydrocarbon,CFC,polar-polar,nonpolar-polarbinary and multicomponent *** on the complete predictive capability,a comparisonbetween the Wong-Sandler and the mixing rule proposed was *** results indicate that thenew mixing rule is in general superior to the Wong-Sandler’s,and the binary interaction parameteras required by the latter is removed,which reduces computing effort and is reliable in predictions ofvapor-liquid equilibria from low pressures to high pressures.

关键词： vapor-liquid equilibria equation of state mixing rule

Effect of post-bond heat treatment on the microstructure and high temperature mechanical property of a TLP bonded γ'-strengthened co-based single crystal superalloy

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Journal of Materials Science & Technology 2021年第21期80卷 244-258页

作者： S.y.Wang y.Sun C.y.Cui X.F.Sun y.Z Zhou y.M.Ma H.L.An Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China Harbin Welding Institute China Academy of Machinery Science and TechnologyHarbin 150028China

Post-bond heat treatment(PBHT) applied to a transient liquid phase(TLP) bonding joint is an effective approach to remove the brittle borides and improve its ***,we proposed two types of PBHT strategies to obtain a TLP bonded γ'-strengthened Co-based single crystal superalloy,and the microstructural characteristics and tensile properties of the two heat treated joints were compared to identify the optimal PBHT *** evolution of the brittle boride in the joint after the PBHT was studied by using in-situ *** experimental results allowed to provide a theoretic model to quantitatively evaluate the distribution of the brittle phase after the optimal PBHT and analyze the joint fractures to understand the failure *** obtained results revealed that a post-bond solid solution treatment performed to the joint at a high temperature(over 1275℃) could decrease the area fraction of the boride from 7.2 % to 1.4 % and increase the elongation from 1.9 % to 7.8 %.This work emphasizes the relevance of solid solution temperature when a PBHT strategy is applied.

关键词： Transient liquid phase(TLP) γ'-strengthened co-based single crystal superalloy Heat treatment sequence Brittle boride Tensile property

Molecular Dynamics Simulation for Grain Boundary Deformation under Tensile Loading Condition

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Journal of Materials Science & Technology 2001年第1期17卷 145-146页

作者： Kim, y.S. Choi, D.y. Won, S.y. Dep. of Mech. Eng. Kyungpook Natl. Univ. Kyungpook South Korea

MD (molecular dynamics) simulations have been performed to observe the behavior of a grain boundary in the α-Fe plate under 2-dimensional loading. In MD simulation, the acceleration of every molecule can be achieved from the potential energy and the force interaction between this molecule and other molecules , and the integration of the motion equation by using Verlet method gives the displacement of each molecule. Initially, four α-Fe rectangular plates having different misorientation angles of the grain boundary are modeled by using the Johnson potential and the Morse potential. The potential energy of the grain boundary system is compared with that of the perfect structure model. Also, the width of the grain boundary can be obtained by investigating the local potential energy distribution. The tensile loading for each grain boundary model is applied and the behavior of the grain boundary is studied. From this study it is clarified that in the case of using the Johnson potential, the obvious fracture mechanism occurs along the grain boundary, and in the case of using the Morse potential, the diffusion of the grain boundary appears instead of the grain boundary fracture.

关键词： Simulation Molecular Dynamics Simulation for Grain Boundary Deformation under Tensile Loading Condition

Quaternion methods and models of regular celestial mechanics and astrodynamics

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Applied Mathematics and Mechanics(English Edition) 2022年第1期43卷 21-80页

作者： y.N.CHELNOKOV Institute of Precision Mechanics and Control Russian Academy of SciencesSaratov410031Russia

This paper is a review,which focuses on our work,while including an analysis of many works of other researchers in the field of quaternionic *** regular quaternion models of celestial mechanics and astrodynamics in the Kustaanheimo-Stiefel(KS)variables and Euler(Rodrigues-Hamilton)parameters are *** models are derived by the quaternion methods of mechanics and are based on the differential equations of the perturbed spatial two-body problem and the perturbed spatial central motion of a point *** paper also covers some applications of these *** and Scheifele are known to have doubted that quaternions and quaternion matrices can be used efficiently to regularize the equations of celestial ***,the author of this paper and other researchers refuted this point of view and showed that the quaternion approach actually leads to efficient solutions for regularizing the equations of celestial mechanics and *** paper presents convenient geometric and kinematic interpretations of the KS transformation and the KS bilinear relation proposed by the present *** general(compared with the KS equations)quaternion regular equations of the perturbed spatial two-body problem in the KS variables are *** equations are derived with the assumption that the KS bilinear relation was not *** main stages of the quaternion theory of regularizing the vector differential equation of the perturbed central motion of a point particle are presented,together with regular equations in the KS variables and Euler parameters,derived by the aforementioned *** also present the derivation of regular quaternion equations of the perturbed spatial two-body problem in the Levi-Civita variables and the Euler parameters,developed by the ideal rectangular Hansen coordinates and the orientation quaternion of the ideal coordinate *** paper also gives new results using quaternionic methods in the pertur

关键词： celestial mechanics astrodynamics perturbed spatial two-body problem central motion regularization Levi-Civita and Kustaanheimo-Stiefel(KS)variables Euler parameter quaternion

Helicobacter pylori infection

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World Journal of Gastroenterology 2000年第1期6卷 20-31页

作者： Vandenplas y Academisch Ziekenhuis Kinderen Free University of BrusselsBrusselsBelgium

IS THERE ANyTHING NEW?Helicobacter pylori has been for many years aforgotten bacterium,since the first report on thisspiral organism dated from the 19th *** as in 1906,an association between a spiralorganism and gastr... 详细信息

关键词： Subject headings Helicobacter pylori gastritis Helicobacter infection