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EXPERIMENTAL AND ThEORETICAL INVESTIGATION OF PSEUDOELASTIC hYSTERESIS IN ShAPE MEMORY ALLOYS

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Acta Metallurgica Sinica(English Letters) 1999年第3期12卷 235-240页

作者： Gong, S.K. Xu, h.b. beijing Univ of Aeronautics and Astronautics Beijing China

The pseudoelastic hysteresis loop associated with phase equilibrium and the stress relaxation on the yield line were investigated, and the theoretical description was confirmed by deformation controlled load-deformation measurements on CuZnAl single crystals. It was found that in a loading-unloading process, the states of shape memory alloys run through a hysteresis loop, and the points that trigger the internal yield and recovery inside the pseudoelastic hysteresis loop define a line that traverses the hysteresis loop from the upper left to the lower right corner. This line was interpreted as a line of unstable phase equilibrium according to the thermodynamic arguments, which determines also the tendency for stress relaxation on the yield line section and for a stress growth on the recovery line section.

关键词： Aluminum copper alloys hysteresis Stress relaxation

Ab-Initio Study of Cobalt Impurity Effects on Phonon Spectra, Mechanical and Thermal Properties of Single Wall Carbon Nanotube （5,0）

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Chinese Physics Letters 2014年第4期31卷 110-113页

作者： h. Tashakori b. Khoshnevisan F. Kanjouri Faculty of Physics University of Kashan Kashan Iran Faculty of Physics Kharazmi University Karaj Iran

We use density functional perturbation theory based on the pseudo-potential to calculate the phonon spectrum, phonon density of states, specific heat capacity and mechanical properties of pristine and cobalt doped （5,0） single wall carbon nanotube （CNT）. In the calculations, we consider one Co atom in the center of the unit cell of the tube and it is shown that the pristine （5~0） CNT is nonmagnetic while the Co-doped tube becomes magnetic. Young＇s modulus for both systems is about 1 TPa （＇after Co-doping it goes slightly higher） and the Poisson ratio for the pristine tube becomes quite a bit larger than the doped one. On the other hand, the calculated value of radial breath mode for the pristine CNT is in good agreement with the experimental reports while after Co-doping it is increased. In addition, heat capacity of the doped CNT is reduced, which leads to some important empirical applications.

关键词： Wall Carbon Nanotube Ab-Initio pseudo-potential

Entanglement and Its Dynamics with Atomic Spontaneous Decay

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Chinese Physics Letters 2008年第7期25卷 2492-2495页

作者： h. A. hessian A.-b. A. Mohamed Faculty of Science Assiut University Assiut Egypt

The atomic decay for a two-level atom interacting with a single mode of electromagnetic tield is considered. For a chosen initial state, the exact solution of the master equation is found. Therefore, effect of the atomic damping on entanglement （purity loss）, degree of entanglement by the negativity, mutual information and atomic coherence through the master equation are studied.

关键词： the power-law exponents precipitation durative abrupt precipitation change

The Gas-to-Dust Relation in the Dark Cloud L1523-Observational Evidence for CO Gas Depletion

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Chinese Journal of Astronomy and Astrophysics 2008年第6期8卷 686-692页

作者： h.G.Kim b.G.Kim J.h.Jung Korea Astronomy and Space Science Institute 61-1 Hwaam Yuseong Daejeon 305-348 Korea

Correlation between gas and dust column density has been studied for the dark globule L1523. The 13CO（J=1→0） emission is used for tracing the gas, and the IR emissions, for tracing the dust constituent. In order to match the beam resolution between the images, a beam de-convolution algorithm based on the Maximum Correlation Method （MCM） was applied on the Infrared Astronomical Satellite （IRAS） data. The morphology of 13CO column density map shows a close correlation to that of 100μm dust optical depth. The distribution of the optical depth at 100 μm follows that of gas column density more closely than does the flux map at either 60 or 100μm. The ratio of the 13CO column density to the 100μm optical depth shows a decreasing trend with increasing dust optical depth in the central part, indicating possible molecular gas condensation onto dust particles. The excessive decrease in the CO column density in the envelope may most probably be due to the photo-dissociation of CO molecules.

关键词： ISM: clouds ISM: dust ISM: molecules

An Investigation of Ionic Flows in a Sphere-Plate Electrode Gap

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Plasma Science and Technology 2013年第10期15卷 1012-1019页

作者： h.Z.ALISOY S.ALAGOZ G.T.ALISOY b.b.ALAGOZ Department of Electrical-Electronics Inonu University Department of Physics Inonu University Department of Mathematics Inonu University

This paper presents analyses of ion flow characteristics and ion discharge pulses in a sphere-ground plate electrode system. As a result of variation in electric field intensity in the electrode gap, the ion flows towards electrodes generate non-uniform discharging pulses. Inspection of these pulses provides useful information on ionic stream kinetics, the effective thickness of ion cover around electrodes, and the timing of ion clouds discharge pulse sequences. A finite difference time domain （FDTD） based space-charge motion simulation is used for the numerical analysis of the spatio-temporal development of ionic flows following the first Townsend avalanche, and the simulation results demonstrate expansion of the positive ion flow and compression of the negative ion flow, which results in non-uniform discharge pulse characteristics.

关键词： ion flow FDTD simulation space charge motion

EFFECT OF COLD WORKING ON ThE AGING PROPERTIES OF Cu-Cr-Zr-Mg ALLOY bY ARTIFICIAL NEURAL NETWORK

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Acta Metallurgica Sinica(English Letters) 2004年第5期17卷 741-746页

作者： J.h.Su h.J.Li Q.M.Dong P.Liu b.X.Kang b.h.Tian CollegeofMaterialsScienceandEngineering NorthwesternPolytechnicalUniversityXi＇an710072China GollegeofMaterialsScienceandEngineering HenanUniversityofScienceandTechnologyLuoyang471003China

A developmental research has been carried out to deal with the high performance of Cu-Cr-Zr-Mg lead frame alloy by artificial neural network (ANN). Using the cold working to assist in the aging hardening can improve the the hardness and electrical conductivity properties of Cu-Cr-Zr-Mg lead frame alloy. This paper studies the effect of different extent of cold working on the aging properties by a supervised ANN to model the non-linear relationship between processing parameters and the properties. The back-propagation (bP) training algorithm is improved by Levenberg-Marquardt algorithm. A basic repository on the domain knowledge of cold worked aging processes is established via sufficient data mining by the network. The predicted values of the ANN coincide well with the tested data. So an important foundation has been laid for prediction and optimum controlling the rolling and aging properties of Cu-Cr-Zr-Mg alloy.

关键词： Cu-Cr-Zr-Mg alloy cold working aging artificial neural network (ANN)

Dissolution Mechanism of a Zr Rich Structure in a Ni_3Al base Alloy

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Journal of Materials Science & Technology 2011年第10期27卷 885-892页

作者： h.b.Motejadded M.Soltanieh S.Rastegari School of Materials Science and Engineering Iran University of Science and Technology

In the present research, the dissolution mechanism of a Zr rich structure during annealing of a Ni3Al base alloy containing Cr, Mo, Zr and b, was investigated. The annealing treatments were performed up to 50 h at 900, 1000 and 1100℃. The alloy used in this investigation was produced by vacuum-arc remelting technique. The results show that at the beginning of the process, a mixed interface reaction and local equilibrium （long range diffusion） mechanism controls the dissolution process. After a short time, this mechanism changes and the dissolution mechanism of the Zr rich structure changes to only long range diffusion of Zr element. According to this mechanism, the activation energy of this process is estimated to be about 143.3 ***-1. Also the phases that contribute to this structure and the transformations that occur at the final steps of solidification of this alloy were introduced. According to the results, at the final step of solidification, a peritectic type reaction occurs in the form of L＋ y→Ni7Zr2 and →-Ni7Zr2 segregates from the melt. Following this transformation, →-Ni7Zr2 eutectic separates from the remaining Zr rich liquid. The solidification process will be terminated by a ternary eutectic reaction in the form of L→y＋Ni5Zr＋Ni7Zr2.

关键词： Ni3Al base alloy Microstructure Dissolution kinetics Activation energy

Coarsening Kinetics of γ' Precipitates in Dendritic Regions of a Ni_3 Al base Alloy

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Journal of Materials Science & Technology 2012年第3期28卷 221-228页

作者： h.b.Motejadded M.Soltanieh S.Rastegari School of Metallurgy and Materials Engineering Iran University of Science and TechnologyTehranIran

Coarsening behavior of γ＇ precipitates in the dendritic regions of a Ni 3 Al base alloy containing chromium,molybdenum,zirconium and boron was *** treatment was performed up to 50 h at 900,1000 and 1100℃.The alloy was produced by vacuum-arc remelting *** show that coarsening of the γ＇ precipitates in this complex alloy containing high volume fractions of γ＇ phase follows Lifshitz-Slyozov-Wagner（LSW） *** activation energy of the γ＇ precipitates was evaluated to be about 253.5 ***-1 which shows that the growth phenomenon is controlled by volume diffusion of *** an innovative approach,diffusion coefficient of the solute element（s） and the interfacial energy between γ＇ precipitates and γ＇（matrix） were estimated at 900,1000 and 1100℃.Accordingly,the interfacial energies at 900,1000 and 1100℃ are 4.49±1.48,2.08±0.69 and 0.98±0.32 mJ.m-2,*** the diffusivities of solute element（s） at these temperatures are 3.41±1.08,30±9.5 and 145.15±45.85（10-15 m-2.s-1）,respectively.

关键词： Ni3 Al base intermetallic Coarsening kinetics Activation energy

CFD-DEM simulation of a pseudo-two-dimensional spouted bed comprising coarse particles

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Particuology 2019年第2期17卷 171-180页

作者： b. Mahmoodi S.h. hosseini G. Ahmadi llam Gas Treating Company llam Iran Department of Chemical Engineering llam University llam 69315-516 Iran Department of Mechanical and Aeronautical Engineering Clarkson University Potsdam NY 13699-5725 USA

In the present study, computational fluid dynamics (CFD) and the discrete element method (DEM) are used in conjunction with the Eulerian-Lagrangian method to simulate a pseudo-two-dimensional spouted bed comprising coarse 6-mm particles. The open-source OpenFOAM code is used to solve the governing equations. The predicted vertical particle velocity along the bed axis, particle velocity profiles in the radial directi on, power spectral den sity, time-averaged particle velocity vectors, bed pressure drop, and solid flow pattern are evaluated and compared with existing experimental data. Good agreement is found between the CFD-DEM results and the measured data. It is also shown that the present CFD-DEM model accurately predicts the particle flow pattern throughout the bed. It is found that the drag force, solid stresses, and gravity play important roles in the CFD-DEM simulation of a spouted bed comprising coarse particles.

关键词： CFD-DEM Pseudo-2D spouted bed hydrodynamics Coarse particles