检索结果-南通市图书馆

Applied mathematics and mechanics(English Edition) 2016年第6期37卷 725-740页

作者： A.R.SETOODEH m.rezaei m.R.ZENDEHDEL SHAHRI Faculty of mechanical and Aerospace Engineering Shiraz University of Technology

The linear and nonlinear torsional free vibration analyses of functionmly graded micro/nuno-tubes （FGmTs） are analytically investigated based on the couple stress theory. The employed non-classical continuum theory contains one material length scale parameter, which can capture the small scale effect. The FGmT model accounts for the through-radius power-law variation of a two-constituent material. Hamilton＇s principle is used to develop the non-classical nonlinear governing equation. To study the effect of the boundary conditions, two types of end conditions, i.e., fixed-fixed and fixed-free, are considered. The derived boundary value governing equation is of the fourthorder, and is solved by the homotopy analysis method （HAm）. This method is based on the Taylor series with an embedded parameter and is capable of providing very good approximations by means of only a few terms, if the initial guess and the auxiliary linear operator are properly selected. The analytical expressions are developed for the linear and nonlinear natural frequencies, which can be conveniently used to investigate the effects of the dimensionless length scale parameter, the material gradient index, and the vibration amplitude on the natural frequencies of FGmTs.

关键词： torsional vibration nonlinear vibration micro/nano-tube functionallygraded material (FGm) couple stress theory size effect

Syngas Production by methane Reforming with Carbon Dioxide on Noble metal Catalysts

在线全文

学校读者我要写书评

暂无评论

Journal of Natural Gas Chemistry 2006年第4期15卷 327-334页

作者： m.rezaei S.m.Alavi S.Sahebdelfar Zi-Feng Yan Chemical Engineering Department Iran University of Science and TechnologyP.O.Box 16315-67TehranIran State Key Laboratory for Heavy Oil Processing Key Laboratory of CatalysisCNPCChina University of PetroleumDongying 257061ShandongChina Petrochemical Research & Technology Company (NPC-RT) TehranIran

A series of noble metal catalysts （Ru, Rh, Ir, Pt, and Pd） supported on alumina-stabilized magnesia （Spinel） were used to produce syngas by methane reforming with carbon dioxide. The synthesized catalysts were characterized using BET, TPR, TPO, TPH, and H2S chemisorption techniques. The activity results showed high activity and stability for the Ru and Rh catalysts. The TPO and TPH analyses indicated that the main reason for lower activity and stability of the Pd catalyst was the formation of the less reactive deposited carbon and sintering of the catalyst.

关键词： noble metal syngas dry reforming carbon dioxide methane

Preparation and thermal treatment of Pd/Ag composite membrane on a porousα-alumina tube by sequential electroless plating technique for H_2 separation

在线全文

学校读者我要写书评

暂无评论

Journal of Natural Gas Chemistry 2008年第4期17卷 321-326页

作者： E.Navaei Alvar m.Reza Golmohammadi m.rezaei H.Navaei Alvar A.mardanloo S.Habibzad Nouhian m.Didari Department of mining & metallurgy Engineering Amirkabir University of Technology Sarv Oil & Gas Industries Development Co Department of Chemical Engineering Faculty of EngineeringUniversity of Kashan

Pd/Ag/α-Al2O3 composite membranes were prepared by sequential electroless plating technique. The prepared membranes were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEm）, energy dispersive spectroscopy, and inductively coupled plasma atomic emission spectroscopy techniques （ICP-AES）. Effects of annealing time, Ag content, and air treatment on the hydrogen permeation flux and morphology of the alloys were investigated. The results of the investigation showed that the prepared type of tube had a good potential as substrate for membrane preparation. In addition, a uniform defect-free alloy was prepared by annealing at 550 ℃ in H2 atmosphere. The permeation results showed an increase in H2 permeation flux by increasing the Ag content and the annealing time. In addition, the air treatment of the prepared membranes at 400 ℃ for 1 h changed the morphology of the alloy and substantially enhanced the hydrogen flux.

关键词： Pd/Ag composite membrane electroless plating thermal treatment

Thermodynamic Studies on The Interaction of Nickel With Human Serum Albumin

在线全文

学校读者我要写书评

暂无评论

生物化学与生物物理进展 2003年第5期30卷 732-737页

作者： A.A.SABOURY F.HOSSEINI-KISHANI m.rezaei-TAWIRANI B.RANJBAR Institute of Biochemistry and Biophysics University of ehranTehranIranInstitute of Biochemistry and BiophysicsUniversity of ehranTehranIranFaculty of MedicineMedical University of IlamIlamIranDepartment of BiologyUniversity of Tarbiat ModarresTehranIran

The interaction of human serum albumin with divalent nickel ion was studied by equilibrium dialysis, isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC) and circular dichroism (CD) in 30 mmol/L Tris buffer , pH=7 0. There is a set of 8 identical binding sites for nickel binding on the protein at two temperatures of 300 K and 310 K. The cooperativity in the binding is observed at 310 K. The Hill coefficients at 300 K and 310 K are 0 97 and 1 25, respectively. The interaction between nickel ions and HSA is exothermic. A value of -36 5 kJ for enthalpy of interaction ( 1∶1 stoichiometry) was obtained. The secondary structure of HSA dose not show any change during the binding nickel ions process. However, the tertiary structure of the protein changes, which shows the existence of two natives like states.

关键词：热力学血清蛋白人类镍

Enhancement of SA Algorithm by Intelligent Time Schedule

在线全文

学校读者我要写书评

暂无评论

Enhancement of SA Algorithm by Intelligent Time Schedule

Cross-focusing of two chirped Gaussian laser beams and THz wave generation in plasmas of multi-ion species under a weakly relativistic and ponderomotive regime

第二十九届中国控制会议

作者： K.Shojaee G. m.Behnam T. H.Shakouri G. m.rezaei Dep.of Electrical and Computer Eng. University of Tehran mechatronics Laboratory(LIm) Politecnico di Torino Dep.of Industrial Engineering University of Tehran Dep.of mechanical&Aerospace Eng. Science&Research Branch Islamic Azad University

In this paper we present a glancing review of how to define the time schedule of Simulated Annealing（SA） algorithm in different articles that applied them to solve the traveling salesman problem（TSP）.In the following subjects we introduce a new definition of this concept in relation to other *** other word,we claim a novel description of initial temperature,markov chain and final temperature to the basic algorithm of SA that gives an introduction to New Time Schedule Simulated Annealing（NTSSA）.In this method,the dynamic coincidence of time schedule parameters and temperature conditions is a possible happening among the searching *** continuation we present the obtaining results of proposed algorithm in solving TSP in comparison with basic methods of SA and other intelligent optimization *** surprising improvement in results obtained by this approach shows the efficiency of NTSSA in contrast with other basic optimization methods.

关键词： Combinatorial Optimization Traveling Salesman Problems Simulated Annealing Time Schedule

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Plasma Science and Technology 2022年第10期24卷 1-11页

作者： m R JAFARI mILANI S rezaei m J JAFARI Photonics and Quantum Technologies Research School Nuclear Science and Technology Research InstituteTehran 14665-678Iran Plasma and Fusion Research School Nuclear Science and Technology Research InstituteTehran 14399-51113Iran

The generation of terahertz(THz)waves via the beating of two high-intensity chirped Gaussian lasers in a multi-ion-species plasma is numerically studied by taking into account the weak relativistic and ponderomotive regime of *** coupled differential equations for beamwidth parameters are extracted by introducing the dielectric function of such plasma and using WKB and paraxial ray *** amplitude of THz radiation at beat frequency resulting from the nonlinear current density induced by the beat ponderomotive force of the cross-focusing of beams was *** impacts of the chirp frequency parameter,initial laser intensity and initial ionic species density(specifically,the presence of singly and doubly charged ions)in the plasma on THz generation were *** numerical results reveal that THz radiation generation strongly depends on the chirp frequency parameter.A specific range of chirp frequencies exists for self-focusing as well as THz generation with a'turning point',where the THz emission reaches its maximum *** results show that the strength of self-focusing and consequently the generated THz radiation are reduced by increasing the density of doubly charged ionic species in the plasma due to the suppression of the nonlinear effects.

关键词： laser–plasma interaction THz generation chirped Gaussian laser beams

Effective thermal conductivity of an intact heterogeneous limestone

在线全文

学校读者我要写书评

暂无评论

Journal of Rock mechanics and Geotechnical Engineering 2020年第4期12卷 682-692页

作者： A.P.S.Selvadurai S.m.rezaei Niya Department of Civil Engineering and Applied mechanics McGill UniversityMontrealQCH3A 0C3Canada Royal melbourne Institute of Technology MelbourneAustralia

The Cobourg limestone is a very low porosity rock consisting of lighter nodular regions that are predominantly calcite and darker regions consisting of calcite,quartz,dolomite,and an appreciable clay *** paper presents the application of the theory of multi-phasic composites to estimate the possible maximum effective thermal conductivity of the heterogeneous *** thermal conductivity estimates are expected to be representative of the intact rock,without fractures or fissures that can influence the heat conduction *** estimates are therefore indicative of the thermal properties of the rock in undisturbed regions unaffected by the influences of stress relief and excavation damage during construction of deep ground repositories for the disposal of heat-emitting nuclear waste.

关键词： Thermal conductivity Cobourg limestone multi-phasic approach Voigt,Reuss and Hill estimates Hashin and Shtrikman bounds Computational modeling

Gain enhancement in two-stream free electron laser with a planar wiggler and an axial guide magnetic field

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2012年第9期21卷 247-250页

作者： S.Saviz Z.rezaei Farzin m.Aghamir Plasma Physics Research Center Science and Research BranchIslamic Azad University Department of Physics University of Tehran

The theory for a two-stream free electron laser （FEL） consisting of a relativistic electron beam transported alongthe axis of a planar wiggler in the presence of an axial guiding magnetic field is proposed and investigated. The electron trajectories and the small signal gain are derived. The characteristic of the linear gain and the normalized maximum gain are studied numerically. The result shows that the normalized maximum gain is considerably enhanced in comparison with that of the single stream. The effect of the difference between the energies of the two beams in this configuration of FEL is also considered, and we find that the gain is affected by the energy differences between groups 1 and 2.

关键词： wo-stream free-electron laser

Effects of CO_2 content on the activity and stability of nickel catalyst supported on mesoporous nanocrystalline zirconia

在线全文

学校读者我要写书评

暂无评论

Journal of Natural Gas Chemistry 2008年第3期17卷 278-282页

作者： m. rezaei S.m. Alavi S. Sahebdelfar Zi-Feng Yan Chemical Engineering Department Faculty of Engineering University of Kashan Iran Chemical Engineering Department lran University of Science and Technology Tehran Iran Petrochemical Research ＆ Technology Company （NPC-RT） Tehran Iran State Key Laboratory for Heavy Oil Processing Key Laboratory of Catalysis CNPC China University of Petroleum Dongying 257061 Shandong China

The effects of carbon dioxide content on the catalytic performance and coke formation of nickel catalyst supported on mesoporous nanocrystalline zirconia with high surface area and pure tetragonal crystalline phase were investigated in methane reforming with carbon dioxide. The samples were characterized by XRD, BET, TPR, TPO, TPH, TEm, and SEm techniques. The catalyst prepared showed high surface area and a mesoporous structure with a narrow pore size distribution. The obtained results revealed that the increase in CO2 content increased the methane conversion and stability of the catalyst and significantly reduced the coke deposition. The TPH analysis showed that several species of carbon with different reactivities toward hydrogenation were deposited on the spent catalysts employed under different CO2 contents.

关键词： Ni catalysts carbon dioxide reforming coke deposition

Effect of ECAP consolidation temperature on the microstructure and mechanical properties of Al-Cu-Ti metallic glass reinforced aluminum matrix composite

在线全文

学校读者我要写书评

暂无评论

Journal of materials Science & Technology 2017年第9期33卷 1031-1038页

作者： m.R.rezaei S.G.Shabestari S.H.Razavi School of metallurgy and materials Engineering Iran University of Science and Technology (IUST) Center of Excellence for High Strength Alloys Technology (CEHSAT) School of Metallurgy and Materials EngineeringIran University of Science and Technology (IUST)

Al;Cu;Ti;metallic glass（AmG） reinforced Al matrix composites were consolidated by equal channel angular pressing（ECAP） process. The effects of ECAP consolidation temperature ranging from room temperature to just below the first crystallization temperature of metallic glass on the consolidation of composites were investigated in terms of the relative densities, structural evolutions and mechanical properties of composites. Some intermetallic compounds included Al;CuTi;, Al;Ti and Al;Cu;precipitated from metallic glass particles at consolidation temperature of 300?C. Consolidation temperature did not affect the matrix grains size of the composite. Quantitative analysis revealed that the distribution of reinforcing particles was considerably dependent on consolidation temperature. Density of the composite was increased by increasing the consolidation temperature to 250?C. The composite consolidated at250?C through ECAP process, exhibited the best combination of yield strength and ductility of 184 mPa and 48%, respectively.

关键词： Al matrix composite(AmC) Equal channel angular pressing(ECAP) Consolidation temperature Glass particles