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Dynamic Recrystallization of a Cr-Ni-mo-Cu-Ti-V Precipitation Hardenable Stainless Steel

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Journal of materials Science & Technology 2007年第6期23卷 775-778页

作者： A.momeni A.Shokuhfar S.m.Abbasi Advanced materials Research Lab Mechanical DepartmentKNT University of TechnologyTehranIran

In this research, the dynamic recrystallization （DRX） behavior of an as-cast precipitation hardenable （PH） stainless steel was investigated by conducting hot compression tests at temperatures between 950-1150℃ and under strain rates of 0.001-1 s^-1. The flow stress curves show that the DRX is responsible for flow softening during hot compression. The effects of temperature and strain rate on the strain and stress corresponding to peak point （εp and σp） of flow curve were analyzed individually. It is realized that, they increase with strain rate and decrease with temperature. The relationship between Zener-Hollomon parameter （Z） and εp was investigated and the equation of εp=4.3×10^-4^0.14 was proposed. The strain for the maximum rate of DRX （εmax） was determined under different deformation conditions. Therefore, it is realized that it increases with Z parameter and vise versa. On the basis of obtained results, the equation of εmax=9.5 × 10^-4Z0.12 was proposed.

关键词： Dynamic recrystallization Hot compression Precipitation hardening stainless steel

magnetohydrodynamic Activity During Limiter Biasing on the CT-6B Tokamak

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Chinese Physics Letters 2001年第3期18卷 393-395页

作者： KHORSHID Pejman WANG Long YANG Xuan-Zong FENG Chun-Hua ZHANG Peng-Yun QI Xia-Zhi ROUHANI Shahriar RAHImITABAR m.Reza AGHAmIR m.Farzin GHORANNEVISS mahmud HANTEZADEH m.Reza Institute of Physics Chinese Academy of SciencesBeijing 100080 Plasma Physics Research Centre Azad UniversityTehranIran Institute for Studies in Theoretical Physics and mathematics TehranIran

magnetohydrodynamic phenomena in the CT-6B Tokamak based on mirnov oscillations have been investigated by applying the limiter biasing potentials and changing the vacuum chamber gas pressure and plasma *** results show that setting up a radial electric field at the plasma edge could drive electromagnetic instabilities in the tokamak *** oscillation frequency upon application of a positive bias decreases about 10-15%and then after a delay time,τ_(d)=2.5-3 ms increases about 20-25%with respect to their value without *** the negative bias regime the oscillation frequency increases about 10%in 1 ms after the application of the bias *** poloidal rotation velocity changes during two steps are related to its link with the radial electric field and the time scale of the density *** frequency of oscillations increases with the increasing chamber gas pressure and decreases with the increasing the outward plasma displacement.

关键词： Tokamak oscillation tokamak

magnetic Properties of Nd-Fe-B Sintered magnet Powders Recovered by Yb metal Vapor Sorption

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Journal of Rare Earths 2004年第1期22卷 152-156页

作者： Horikawa T Itoh m Suzuki Shunji machida K Collaborative Research Center for Advanced Science and Technology Collaborative Research Center for Advanced Science and TechnologyCollaborative Research Center for Advanced Science and TechnologyCollaborative Research Center for Advanced Science and Technology Osaka University Osaka 565-0871 Japan Osaka University Osaka 565-0871 Japan Osaka University Osaka 565-0871 Japan Osaka University Osaka 565-0871 Japan

Fine ground powders of Nd-Fe-B sintered magnet bulks (particle size=46～125 μm in diameter) were coated and alloyed with Yb metal by sorbing them. A significant recovery of the decreased magnetic properties of the ground powders (remanence B r=～0.95 T, coercivity H cj =～227 kA·m -1 and maximum energy product (BH) max=～48 8 kJ·m -3) was observed in accordance with increasing temperature up to 800 ℃. The sorbing temperature and time for Yb metal vapor were optimized and after heating at 800 ℃ for 90 min and annealing subsequently at 610 ℃ for 60 min, the B r, H cj and (BH) max values were increased to be 0.98 T, 712 kA·m -1 and 173 kJ·m -3, respectively. From the microstructural characterizations of resulting samples by using X-ray diffraction (XRD), scanning electron microscopy (SEm), and electron probe X-ray microanalyzer (EPmA), it is found that the sorbed Yb metal uniformly covers the surface and diffuses to the Nd-rich grain boundary of fine ground powders of Nd-Fe-B sintered magnet bulks forming a (Nd,Yb)Fe 2 phase.

关键词： metal materials Nd 2Fe 14B sintered magnets metal vapor sorption magnetic properties recovery rare earths

Exact Solutions of the Dirac Equation for an Electron in a magnetic Field with Shape Invariant method

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Chinese Physics Letters 2008年第11期25卷 3848-3851页

作者： m. R. Setare O. Hatami Department of Science University of Kurdistan Pasdaran Ave. Sanandaj Iran

Based on the shape invariance property we obtain exact solutions oI the Dirac equation for an electron moving in the presence of a certain varying magnetic field, then we also show its non-relativistic limit.

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

Analysis of Rheological Behavior of Some Aqueous PEO Gels under Thermal Treatment

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Chinese Physics Letters 2009年第7期26卷 362-365页

作者： m. Todica and C. V. Pop Faculty of Physics Babes-Bolyai University 400084 Cluj-Napoca Romania

Evolution of viscosity of some aqueous poly （ethylene oxide） gels is observed as functions of polymeric concentration and temperature for samples subjected to thermal shock. The experimental data are analyzed following an appropriate algorithm, and reveal the transient effect from Newtonian to non-Newtonian flow as a function of the polymeric concentration.

关键词： Soft matter liquids and polymers Fluid dynamics

Direct-fed microbes: A tool for improving the utilization of low quality roughages in ruminants

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Journal of Integrative Agriculture 2015年第3期14卷 526-533页

作者： mona m Y Elghandour Abdelfattah Z m Salem Jose S martínez Castaeda Luis m Camacho Ahmed E Kholif Juan C Vázquez Chagoyán Faculty of Veterinary medicine and Animal Science Autonomous University of the State of Mexico Faculty of Veterinary medicine and Animal Science Autonomous University of Guerrero Dairy Science Department National Research Centre

For many years, ruminant nutritionists and microbiologists have been interested in manipulating the microbial ecosystem of the rumen to improve production efficiency of different ruminant species. Removal and restriction of antibiotics subtherapeutic uses from ruminant diets has amplified interest in improving nutrient utilization and animal performance and search for more safe alternatives. Some bacterial and fungal microorganisms as a direct-fed microbial（DFm） can be the most suitable solutions. microorganisms that are commonly used in DFm for ruminants may be classified mainly as lactic acid producing bacteria（LAB）, lactic acid utilizing bacteria（LUB）, or other microorganism＇s species like Lactobacillus, Bifidobacterium, Enterococcus, Streptococcus, Bacillus, Propionibacterium, megasphaera elsdenii and Prevotellabryantii, in addition to some fungal species of yeast such as Saccharomyces and Aspergillus. A definitive mode of action for bacterial or fungal DFm has not been established; although a variety of mechanisms have been suggested. Bacterial DFm potentially moderate rumen conditions, and improve weight gain and feed efficiency. Fungal DFm may reduce harmful oxygen from the rumen, prevent excess lactate production, increase feed digestibility, and alter rumen fermentation patterns. DFm may also compete with and inhibit the growth of pathogens, immune system modulation, and modulate microbial balance in the gastrointestinal tract. Improved dry matter intake, milk yield, fat corrected milk yield and milk fat content were obtained with DFm administration. However, the response to DFm is not constant; depending on dosages, feeding times and frequencies, and strains of DFm. Nonetheless, recent studies have supported the positive effects of DFm on ruminant performance.

关键词： direct-fed microbial(DFm) mode of action ruminants

Electron Acceleration by microwave Radiation Inside a Rectangular Waveguide

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Plasma Science and Technology 2011年第3期13卷 357-361页

作者： B. F. mOHAmED A.m. GOUDA Plasma Physics Department N.R.C. Atomic Energy Authority Cairo Egypt

Electron dynamics in the fields associated with a transverse magnetic （Tm） wave propagating inside a rectangular waveguide is analytically studied. The relativistic momentum and energy equations for an electron are solved, which was injected initially along the propagation direction of the microwave. Expressions of the acceleration gradient and deflection angle are obtained. In principle, it is shown that the electron can be accelerated in this condition and there is no deflection when the electron is injected from the centre of the waveguide front. However, it is found that the acceleration gradient and deflection angle depend strongly on the parameters of the microwave （intensity, frequency, etc.） and the dimensions of the waveguide.

关键词： waveguide electron acceleration polarized microwave

Evaluation of reliability of Coats-Redfern method for kinetic analysis of non-isothermal TGA

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中国有色金属学会会刊：英文版 2008年第1期18卷 217-221页

作者： R.Ebrahimi-Kahrizsangi m.H.Abbasi Department of Engineering Islamic Azad UniversityNajafabad branch Department of materials Engineering Isfahan University of Technology

A critical examination was made on the reliability of kinetic parameters of nonisothermal thermoanalytical rate measurement by the widely applied Coats-Redfern(CR)*** this purpose,simulated TGA curves were made for reactions with different kinetic models,including chemical,diffusion(Janders)and mixed mechanism at different heating *** results show that,for reactions controlled kinetically by one mechanism,all solid state reaction models show linear trends by use of CR method and this method can not distinct the correct reaction *** reactions with mixed mechanism,the CR method shows nonlinear trends and the reaction models and kinetic parameters can not be extracted from CR *** overall conclusion from this comparative appraisal of the characteristics of the CR approach to kinetic analysis of TGA data is that the CR approach is generally unsuitable for determination of kinetic parameters.

关键词：动态分析可靠性分析等温线金属学

DSC study on temperature memory effect of NiTi shape memory alloy

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中国有色金属学会会刊：英文版 2006年第B1期16卷 37-41页

作者： N. LIU W. m. HUANG School of mechanical and Aerospace Engineering Nanyang Technological University Singapore 639798

A systematic study on the temperature memory effect (TmE) in a polycrystalline NiTi shape memory alloy was presented. The investigation was carried out through a series of differential scanning calorimeter (DSC) tests. Two types of tests were conducted, namely single-step test and multi-step test. The influence of the step temperature on the peak/trough temperatures in the subsequent heating process and the associated energy absorption/release in the phase transformations was investigated. Using a simple theoretical model, the exact mechanism behind TmE was studied.

关键词：镍钛合金形状记忆合金温度记忆效应相转变差分扫描量热计