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Journal of Materials science & Technology 2014年第2期30卷 134-138页

作者： G.Faraji P.Yavari S.Aghdamifar M.Mosavi Mashhadi Department of Mechanical Engineering University College of EngineeringUniversity of Tehran Department of Mechanical and Aerospace Engineering Science and Research BranchIslamic Azad University

Ultra-fine grained （UFG） cylindrical tubes were produced via recently developed tubular channel angular pressing （TCAP） process through different passes from as-cast AZ91 magnesium alloy. The microstructure and mechanical properties of processed tube through one to four passes of TCAP process at 200℃ were investigated. Microhardness of the processed tube was increased to 98.5 HV after one pass from an initial value of 67 Hr. An increase in the number of passes from one to higher number of passes has no more effect on the microhardness. Yield and ultimate strengths were increased by 4.3 and 1.4 times compared to those in as-cast condition. Notable increase in the strength was achieved after one pass of TCAP while higher number of passes has no more effect. Microstructural investigation shows notable decrease in the grain size to around 500 nm from the primary value of - 150 μm. Dissolution and distribution of hard MglTAI12 phase in the grain boundaries of dynamically recrystallized UFG AZ91 with a mean grain size of - 500 nm was an interesting issue of TCAP processing at 200 ℃ compared to other severe plastic deformation processes.

关键词： Severe plastic deformation Tubular channel angular pressing AZ91 Grain refinement Mechanical behaviour

Kinetics of gadolinium extraction with D2EHPA and Cyanex301 using single drop column

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Rare Metals 2016年第6期35卷 487-494页

作者： Rezvan Torkaman Meisam Torab-Mostaedi Jaber Safdari Mohammad Ali Moosavian School of Chemical Engineering College of EngineeringUniversity of Tehran Nuclear Fuel Cycle Research School Nuclear Science and Technology Research Institute

The extraction kinetics of Gd（III） from the nitric acid medium using bis（2,4,4-trimethylpentyl） dithio- phosphinic acid （Cyanex301） and 2-ethylhexyl phosphoric acid （D2EHPA） in kerosene solution were measured by the single drop technique. The influences of hydrogen ion concentration, gadolinium ion concentration, extractant concentration, column height, and nozzle diameter on the extraction rate were investigated. The forward rate equations for the gadolinium extraction with D2EHPA and Cyanex301 were obtained. Based on the experimental results, the forward extraction rate constant was calculated. With the increase of D2EHPA or Cyanex301 concentration, the drop rising diameter and the value of interfacial tension decrease in the studied system, which shows that D2EHPA or Cyanex301 has interfacial activity as a kind of surfactant. Also, the droplet diameter and interfacial tension decrease with the increase of aqueous solution acidity. The experimental results show that the D2EHPA extractant provides faster extraction rate in comparison with Cyanex301 extractant, and it would be useful in industrial continuous extraction process.

关键词： Reaction kinetics Solvent extraction Single drop column Gadolinium Rare earths

Investigation of parameters influencing erosive wear using DEM

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Friction 2020年第1期8卷 136-150页

作者： Akbar JAFARI Reza ABBASI HATTANI Department of Mechanical Engineering Sirjan University of TechnologySirjan ***Iran

The effects of several parameters on the erosive wear were studied using the discrete element method(DEM).The Finnie model was implemented using an open‐source *** the time integration,the Gear algorithm was used,and to ensure the accuracy of the DEM results,a time‐step sensitivity analysis was *** problem was modeled in two parts:first,the impact of a single particle on a surface was modeled,and then a more general model was prepared to examine the wear of surfaces under the flow of *** effects of the surface area,impact angle,speed,particle size,particle density,Young’s modulus,Poisson’s ratio,and restitution coefficient on the wear were studied numerically,and the results are discussed herein.

关键词： wear erosion Finnie discrete element

Assessment of geochemical and sedimentological characteristics of atmospheric dust in Shiraz,southwest iran

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Geoscience Frontiers 2020年第3期11卷 783-792页

作者： Amir Karimian Torghabeh Biswajeet Pradhan Ashkan Jahandari Department of Earth sciences Faculty of SciencesShiraz UniversityShirazIran The Centre for Advanced Modeling and Geospatial Information Systems(CAMGIS) Faculty of Engineering and ITUniversity of Technology SydneySydneyNSW2007Australia Department of Energy and Mineral Resources Engineering Sejong UniversityChoongmu-gwan209 Neungdong ro Gwangjin-guSeoul05006South Korea Department of Geology Shahid Bahonar University of KermanKermanIran

Geogenic dust is commonly believed to be one of the most important environmental problems in the Middle *** present study investigated the geochemical characteristics of atmospheric dust particles in Shiraz City(south of iran).Atmospheric dust samples were collected through a dry collector method by using glass trays at 10 location sites in May *** composition was analysed through inductively coupled plasma optical emission *** data showed that the dustiest days were usually in spring and summer,particularly in April.X-ray diffraction analysis of atmospheric dust samples indicated that the mineralogical composition of atmospheric dust was calcite+dolomite(24%)>palygorskite(18%)>quartz(14%)>muscovite(13%)>albite(11%)>kaolinite(7%)>gypsum(7%)>zircon=anatase(3%).The high occurrence of palygorskite(16%-23%) could serve as a tracer of the source areas of dust storms from the desert of Iraq and Saudi Arabia to the South of *** electron microscopy indicated that the sizes of the collected dust varied from 50 μm to0.8 μm,but 10 μm was the predominant *** atmospheric dust collected had prismatic trigonal-rhombohedral crystals and semi-rounded irregular ***,diatoms were detected in several samples,suggesting that emissions from dry-bed lakes,such as Hoor Al-Azim Wetland(located in the southwest of iran),also contributed to the dust *** trajectory simulations were performed at the date of sampling by using the NOAA HYSPLIT *** showed that the sources of atmospheric dust in the study area were the eastern area of Iraq,eastern desert of Saudi Arabia,Kuwait and Khuzestan *** Ca/Al ratio of the collected samples(1.14) was different from the upper continental crust(UCC) value(UCC=0.37),whereas Mg/A1(0.29),K/Al(0.22) and Ti/Al(0.07) ratios were close to the UCC value(0.04).This condition favours desert calcisols as the main mineral dust *** of the crustal enrichment factor(EF

关键词： Dust storm Atmospheric dust Heavy metals Diatom Palygorskite Provenance

Performance assessment of a spiral methanol to hydrogen fuel processor for fuel cell applications

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Journal of Natural Gas Chemistry 2012年第5期21卷 526-533页

作者： Foad Mehri Majid Taghizadeh Chemical Engineering Department Babol University of TechnologyP.O.Box 484*** BabolIran

A novel design of plate-type microchannel reactor has been developed for fuel cell-grade hydrogen *** Cu/Zn/Al2O3 was used as catalyst for the reforming reaction,and its effectiveness was evaluated on the mole fraction of products,methanol conversion,hydrogen yield and the amount of carbon monoxide under various operating ***,0.5 wt% Ru/Al2O3 as methanation catalyst was prepared by impregnation method and coupled with MSR step to evaluate the capability of methanol processor for CO *** on the experimental results,the optimum conditions were obtained as feed flow rate of 5mL/h and temperature of 250℃,leading to a low CO selectivity and high H2 *** designed reformer with catalyst coated layer was compared with the conventional packed bed reformer at the same operating *** constructed fuel processor had a good performance and excellent capability for on-board hydrogen production.

关键词： spiral fuel processor hydrogen fuel cell methanol steam reforming

Covalent immobilization and characterization of Rhizopus oryzae lipase on core-shell cobalt ferrite nanoparticles for biodiesel production

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Chinese Journal of Chemical Engineering 2021年第9期34卷 128-136页

作者： Saboura Ashkevarian Jalil Badraghi Fatemeh Mamashli Behdad Delavari Ali Akbar Saboury Research Institute of Applied sciences ACECRShahid Beheshti UniversityTehranIran Institute of Biochemistry and Biophysics University of TehranTehranIran Center of Excellence in Biothermodynamics University of TehranTehranIran

Rhizopus oryzae lipase(ROL)was immobilized on the surface of silica coated amino modified CoFe_(2)O_4 nanoparticles and applied for biodiesel *** results indicated more affinity of the ROL toward its substrate upon immobilization,as revealed by a lower Km value for the immobilized ROL compared to its free *** fluorescence spectroscopy indicated a lower intensity for ROL immobilized on CoFe_(2)O_4 ***,immobilized ROL steady state anisotropy measurements presented lower values,which implied assembly of ROL molecules on magnetic nanoparticles upon immobilization as well as their restricted rotation upon covalent *** stability analysis revealed improved activity at higher temperatures for the immobilized enzyme compared to its free ***,Pace analysis to determine protein thermal stability revealed preservation of the protein conformation in the presence of increasing temperatures upon immobilization on ***,ROL immobilized on CoFe_(2)O_(4)nanoparticles exhibited improved efficiency of biodiesel production in agreement with thermal activity ***,the authors suggest application of the lipase molecules immobilized on CoFe_(2)O_(4)nanoparticles for more efficient biodiesel production.

关键词： Lipase immobilization CoFe_(2)O_(4)magnetic nanoparticles Steady state anisotropy Biodiesel Biocatalysis Protein stability

A comparative study on H_2S removal using Mg–Al spinel(MgAl_2O_4) and MgO/Al_2O_3 nanocomposites

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Chinese Journal of Chemical Engineering 2017年第9期25卷 1329-1334页

作者： S.M.Latifi J.Bakhshi Azghandi A.Salehirad M.Parvini Department of Chemical Technology Iranian Research Organization for Science & Technology Chemical Engineering Oil &Gas Semnan University

In this work MgO/Al_2O_3 nanocomposites with weight ratios from 5% to 25% were synthesized by precipitationimpregnation method and their structural properties were characterized. In the next step, the capability of the nanocomposites in H_2S removal compared to Mg–Al spinel(MgAl_2O_4), synthesized through ion-pair complex precursor route and alumina samples, prepared via sol–gel precipitation methods, was investigated. The results indicated that among the studied sorbents Mg–Al spinel presents a distinctly higher H_2S removal. In addition, the MgO/Al_2O_3 nanocomposites compared to the alumina sorbents, exhibited much better performance in H_2S removal. Also CO_2-TPD analysis reveals higher amounts of basic sites for Mg–Al spinel compared to 25 wt% MgO/75 wt% Al_2O_3 nanocomposite.

关键词： Nanomaterials Adsorption Alumina Desulfurization MgO

On Time-Constant Robust Tuning of Fractional Order [Proportional Derivative] Controllers

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IEEE/CAA Journal of Automatica Sinica 2019年第5期6卷 1179-1186页

作者： Vahid Badri Mohammad Saleh Tavazoei Electrical Engineering Department Sharif University of TechnologyTehranIran

This paper deals with analyzing a newly introduced method for tuning of fractional order [proportional derivative](FO[PD]) controllers to be used in motion control. By using this tuning method, not only the phase margin and gain crossover frequency are adjustable, but also robustness to variations in the plant time-constant is guaranteed. Conditions on the values of control specifications(desired phase margin and gain crossover frequency) for solution existence in this tuning method are found. Also, the number of solutions is analytically determined in this study. Moreover, experimental verifications are presented to indicate the applicability of the obtained results.

关键词： Fractional order controller robustness solution existence tuning method

Transesterification of canola oil over Li/Ca-La mixed oxide catalyst:Kinetics and calcination temperature investigations

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燃料化学学报 2017年第4期45卷 442-448页

作者： Hesam Maleki Mohammad Kazemeini Department of Chemical and Petroleum Engineering Sharif University of Technology

In this research,a solid 1%Li/Ca-La mixed oxide catalyst was prepared using co-precipitation method followed by wet *** prepared catalyst was used in the transesterification reaction of canola oil and methanol for biodiesel *** effects of calcination and reaction temperatures were investigated on the activity of the *** addition,rate of the reaction was studied through a kinetic model for which parameters were *** properties and structure of the catalyst were characterized through the powder X-ray diffraction(XRD),thermogravimetry/derivative thermogravimetry(TG/DTG),and Fourier transform infrared spectroscopy *** these emphasized that the performance of the catalyst corresponded to the generation of the active sites and their thermal activation.

关键词：油共炼基团相对含量固体残渣干基无灰转化率

Selective methanation of carbon monoxide in hydrogen rich stream over Ni/CeO_2 nanocatalysts

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Journal of Rare Earths 2015年第6期33卷 619-628页

作者： Behzad Nematollahi Mehran Rezaei Ebrahim Nemati Lay Catalyst and Advanced Materials Research Laboratory Chemical Engineering Department Faculty of Engineering University of Kashan Institute of Nanoscience and Nanotechnology University of Kashan

In the present work, selective methanation of carbon monoxide in hydrogen rich stream was investigated over Ni/CeO2 nanocatalysts. The obtained results revealed that increasing in nickel loading decreased the BET surface area, pore vohune and nickel dispersion. The 25%Ni/CeO2 with a NiO crystal size of 12 nm exhibited the highest activity in CO methanation reaction and reached to maximum CO conversion and CH4 selectivity at temperatures above 230 ℃. The catalytic results revealed that CO selective methanation well progressed at lower temperatures while CO2 methanation was completely suppressed until CO conversion reached to maximum value.

关键词： methanation nickel cerium oxide high surface area carbon monoxide rare earths