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Performance of a novel bent-up bars system not interacting with concrete

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Frontiers of Structural and Civil Engineering 2019年第6期13卷 1301-1315页

作者： Aydin SHISHEGARAN mohammad reza GHASEMI Hesam VARAEE School of Civil Engineering Iran University of Science and TechnologyTehran 13114-16846Iran Structural Engineering Department of Civil EngineeringUniversity of Sistan and BaluchestanZahedan 98167-45845Iran Structural Engineering Ale Taha Institute of Higher EducationTehran 14888-36164Iran

Increasing the bending and shear capacities of reinforced concrete members is an interesting issue in structural *** recent years,many studies have been carried out to improve capacities of reinforced concrete members such as using post and pre-tensioning,Fiber Reinforced Polymer and other *** paper proposes a novel and significant technique to increase the flexural capacity of simply supported reinforced concrete *** proposed method uses a new reinforcement bar system having bent-up bars,covered with rubber *** technique will avoid interaction of bent-up bars with *** are located in the zone where compressive and tensile forces act against one anothe匚The compressive force in the upper point of the bent-up bars is exerted to the end point of these bars located under neutral ***,the tensile stress is decreased in reinforcements located under the neutral *** will cause the Reinforced Concrete(RC)beam to endure extra loading before reaching yield *** factors may well be considered as reasons to increase bending capacity in the new *** laboratory work together with finite element method analysis were carried out in this ***,bending capacity,ductility,strength,and cracking zone were assessed for the new proposed system and compared with the conventional *** the FEM simulation and the experimental test results revealed that the proposed system has significant impact in increasing the load bearing capacity and the stiffness of the RC *** the present study,an equation is formulated to calculate bending capacity of a new reinforcement bar system beam.

关键词： bending capacity rubber tube stress transfer bent-up bars ductility cracking

Bifurcation in a 3-DOF Airfoil with Cubic Structural Nonlinearity

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Chinese Journal of Aeronautics 2011年第3期24卷 265-278页

作者： Saied IRANI Hamid SARRAFZADEH mohammad reza AMOOZGAR Department of Aerospace Engineering K.N.Toosi University of Technology

Limit cycle oscillations （LCOs） as well as nonlinear aeroelastic analysis of a 3-DOF aeroelastic airfoil motion with cubic restoring moments in the pitch degree of freedom are investigated. Aeroelastic equations of an airfoil with control surface in an incompressible potential flow are presented in the time domain. The harmonic balance （HB） method is utilized to calculate the LCO frequency and amplitude for the airfoil. Also the semi-analytical method has revealed the presence of stable and unstable limit cycles, along with stability reversal in the neighborhood of a Hopf bifurcation. The system response is determined by nu- merically integrating the governing equations using a standard Runge-Kutta algorithm and the obtained results are compared with the HB method. Also the results by the third order HB （HB3） method for control surface are consistent with the other numerical solution. Finally, by combining the numerical and the HB methods, types of bifiarcation, be it supercritical, subcritical, or diver- gent flutter area are identified.

关键词： flutter bifurcation cubic nonlinearity limit cycle oscillations harmonic balance method

A review of the efficacy of traditional Iranian medicine forinflammatory bowel disease

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World Journal of Gastroenterology 2010年第36期16卷 4504-4514页

作者： Roja Rahimi mohammad Abdollahi mohammad reza Shams-Ardekani Faculty of Traditional Medicine Tehran University of Medical SciencesTehran ***Iran Faculty of Pharmacy Pharmaceutical Sciences Research CenterEndocrinology and Metabolism Research InstituteTehran University of Medical SciencesTehran ***Iran

The etiology of inflammatory bowel disease(IBD) is not yet known,but many factors such as defects in the immune system,oxidative stress,microbial content in the gastrointestinal tract,nuclear factor(NF)-κB,nitric oxide(NO),cyclooxygenase-2(Cox-2),and leukotriene B4(LB4) are thought to play a role in its *** traditional Iranian medicine(TIM),several medicinal plants are thought to be effective for the treatment of *** this study,information on all of these remedies were derived from all available old sources such as documents or notes and books and were added to the information derived from modern medical databases covering all in vitro,in vivo and clinical *** some of these plants,only one or two mechanisms of action have been found such as in Cassia fistula,Lepidium sativum,and Bunium ***,for some plants various mechanisms of action are *** example,Commiphora mukul is effective in IBD due to its immunomodulatory,antioxidant,and antibacterial properties and it decreases NF-κB,NO and *** herb,Plantago ovata,has immunomodulatory,antioxidant,anti-inflammatory and wound healing activities and decreases NO and *** the mechanisms of action of these plants,the combination of some of them may be useful because of their many mechanisms of action such as Pistacia lentiscus,Bunium persicum,Solanum nigrum,Plantago ovata,Boswellia,Solanum nigrum,Plantago ovata and Commiphora *** some of the herbal products used in TIM such as oleogum resin from Commiphora myrrha,seeds of Ocimum basilicum,seeds of Linum usitatissimum,gum resin of Dracaena cinnabari,seeds of Plantago major,seeds of Lallementia royleana,and seeds of Allium porrum,there is no or not enough studies to confirm their benefits in *** is suggested that an evaluation of the effects of these plants on different aspects of IBD should be performed.

关键词： Herbal medicine Inflammatory bowel disease Medicinal plants Traditional Iranian medicine

Effects of intermediate Ni layer on mechanical properties of Al–Cu layered composites fabricated through cold roll bonding

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International Journal of Minerals,Metallurgy and Materials 2018年第5期25卷 573-583页

作者： Ali Shabani mohammad reza Toroghinejad Alireza Bagheri Department of Materials Engineering Isfahan University of Technology

Layered composites have attracted considerable interest in the recent literature on metal composites. Their mechanical properties depend on the quality of the bonding provided by the intermediate layers. In this study, we analyzed the mechanical properties and bond strengths provided by the nickel layer with respect to its thickness and nature(either powder or coating). The results suggest that bond strength decreases with an increase in the content of nickel powder. At 0.3 vol% of nickel coating, we found the nature of nickel to be less efficient in terms of bond strength. A different picture arose when the content of nickel was increased and the bond strength increased in nickel coated samples. In addition, the results demonstrate that mechanical properties such as bend strength are strongly dependent on bond strength.

关键词： cold roll bonding Al/Ni/Cu composite mechanical testing metallography

Sol-gel derived nanocrystalline and mesoporous barium strontium titanate prepared at room temperature

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Particuology 2011年第3期9卷 235-242页

作者： mohammad reza mohammadi Derek J.Fray Department of Materials Science & Engineering Sharif University of Technology Department of Materials Science & Metallurgy University of Cambridge

Perovskite-type barium strontium titanate （BST） thin films and powders with nanocrystalline and mesoporous structure were prepared by a straightforward particulate sol-gel route at room temperature. The prepared sol had a narrow particle size distribution of about 20 nm. X-ray diffraction （XRD） revealed that phase composition and preferable orientation growth of BST depended upon the annealing temperature. Transmission electron microscope （TEM） images showed that the crystallite size of the powders decreased with increasing annealing temperature from 8 nm at 25 ℃ down to 5 nm at 800 ℃. Field emission scanning electron microscope （FE-SEM） analysis and atomic force microscope （AFM） images revealed that BST thin films had mesoporous and nanocrystafiine structure with average grain size of 3Onm at 600 ℃. Based on Brunauer-Emmett-Teller （BET） analysis, the synthesized BST showed mesoporous structure containing nnres with needle, and nlate shanes and BET surface area in the range of 49-32 m^2/g at 500-800℃

关键词： Barium strontium titanate Room temperature Sol-gel chemistry Nanostructure

Solvent extraction-separation of La(III),Eu(III) and Er(III) ions from aqueous chloride medium using carbamoyl-carboxylic acid extractants

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Journal of Rare Earths 2016年第1期34卷 91-98页

作者： Reyhaneh Safarbali mohammad reza yaftian abbasali zamani Phase Equilibria Research Laboratory Department of Chemistry Faculty of Science University of Zanjan 45371-38791 Zanjan Iran Department of Environmental Science Faculty of Science University of Zanjan 45371-38791 Zanjan Iran

N,N-dibutyldiglycol amic acid （HL1） and N,N-dioctyldiglycol nmic acid （HLu） were synthesized and characterized by conventional spectroscopic methods. These molecules were examined as extractants for extraction-separation of La（Ⅲ）, Eu（Ⅲ） and Er（Ⅲ）, as representative ions of light, middle and heavy rare earths, from aqueous chloride solutions. The analysis of the extraction equilibria revealed that the extracted species of lanthanum and europium ions by both of the extractants had a 1：3 metal to ligand ratio It was suggested that erbium ions were extracted into the organic phase via the formation ofEr（LIor Ⅱ）2Cl complexes. The effect of the organic diluents on the extraction-separation efficiency of the studied rare earths by HLI and HLⅡ was investigated by comparing the results obtained in dichloromethane and carbon tetrachloride. Regardless to the diluent used, the order of selectivity presented by the investigated extractants was Er（Ⅲ）〉Eu（Ⅲ）〉La（Ⅲ）. It is noteworthy that, a significant enhancement in separation of the studied rare earths by the extractants was achieved in their competitive extraction experiments with respect to that obtained in single component extraction experiments. Applicability of the extractants for the removal of rare earth ions from spent Ni-MH batteries was tested by removal ofLa（Ⅲ）, Eu（Ⅲ） and Er（Ⅲ） ions from simulated leach solution of such batteries.

关键词： rare earths solvent extraction separation recovery amide-carboxylic acid ligands

Optimal PD/PID control of smart base isolated buildings equipped with piezoelectric friction dampers

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Earthquake Engineering and Engineering Vibration 2013年第1期12卷 39-54页

作者： Sadegh Etedali mohammad reza Sohrabi Saeed Tavakoli .Department of Civil Engineering Faculty of EngineeringUniversity of Sistan and Baluchestan Department of Civil Engineering Faculty of EngineeringUniversity of Sistan and Baluchestan Faculty of Electrical and Computer Engineering University of Sistan and Baluchestan

Long-period pulses in near-field earthquakes lead to large displacements in the base of isolated *** dissipate energy in isolated structures using semi-active control,piezoelectric friction dampers（PFD） can be *** performance of a PFD is highly dependent on the strategy applied to adjust its contact *** this paper,the seismic control of a benchmark isolated building equipped with PFD using PD/PID controllers is *** genetic algorithms,these controllers are optimized to create a balance between the performance and robustness of the closed-loop structural *** advantage of this technique is that the controller forces can easily be *** addition,the structure is equipped with only a single sensor at the base floor to measure the base *** seven pairs of earthquakes and nine performance indices,the performance of the closed-loop system is ***,the results are compared with those given by two well-known methods：the maximum possive operation of piezoelectric friction dampers and LQG *** simulation results show that the proposed controllers perform better than the others in terms of simultaneous reduction of floor acceleration and maximum displacement of the ***,they are able to reduce the displacement of the isolator systems for different earthquakes without losing the advantages of isolation.

关键词： seismic isolation semi-active control piezoelectric friction dampers PD/PID controllers

Synthesis and Characterization of Indium Niobium Oxide Thin Films via Sol—Gel Spin Coating Method

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Journal of Materials Science & Technology 2013年第10期29卷 923-928页

作者： Saeed mohammadi mohammad reza Golobostanfard Hossein Abdizadeh School of Metallurgy and Materials Engineering College of EngineeringUniversity of Tehran Center of Excellence for High Performance Materials University of Tehran

In the present study, niobium-doped indium oxide thin films were prepared by sol-gel spin coating technique. The effects of different Nb-doping contents on structural, morphological, optical, and electrical properties of the films were characterized by means of X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, atomic force microscopy （AFM）, UV-Vis spectroscopy, and four point probe methods. XRD analysis confirmed the formation of cubic bixbyite structure of In203 with a small shift in major peak position toward lower angles with addition of Nb. FESEM micrographs show that grain size decreased with increasing the Nb-doping content. Optical and electrical studies revealed that optimum opto-electronic properties, including minimum electrical resistivity of 119.4 × 10^-3 Ω cm and an average optical transmittance of 85% in the visible region with a band gap of 3.37 eV were achieved for the films doped with Nb-doping content of 3 at.%. AFM studies show that addition of Nb at optimum content leads to the formation of compact films with smooth surface and less average roughness compared with the prepared ln2O3 films.

关键词： Indium oxide Nb-doping Sol-gel spin coating Transparent conductive oxide Opto-electronic properties

Performance of passive and reactive profiled median barriers in traffic noise reduction

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第1期12卷 78-86页

作者： mohammad reza MONAZZAM Samaneh Momen Bellah FARD Occupational Hygiene Department School of Public HealthTehran University of Medical Sciences Department of Environmental Science Graduate School of the Environment and EnergyScience and Research BranchIslamic Azad University

Median noise barriers, like parallel noise barriers, can be employed to reduce the impact of traffic on roadside communities via the direct propagation path. The performance of different shapes of median barriers was compared using reactive and passive surfaces and a 2D boundary element method (BEM). In the case of reactive surfaces, quadratic residue diffusers (QRDs) and primitive root diffusers (PRDs) were used on the top and stem surfaces of median barriers. To introduce passive barriers, two different absorbent materials including fibrous material and a grass surface with flow resistivity of 20 000 and 2500 kg/(s·m2), respectively, were similarly applied. The effect of thin absorptive barriers was similar at lower frequencies and better at mid and high frequencies to that of their equivalent rigid barriers. More improvement was achieved by covering the top surface of thick barriers with grass rather than with fibrous material. The performance of QRD and PRD barriers where the diffuser was located on the top surface was more frequency dependent than that of barriers coated with fibrous material. A comparison of the average A-weighted insertion loss in the thick barriers showed that the greatest improvement (2.59 dB (A)) was achieved using a barrier of 30-cm thickness covered with grass.

关键词： Absorption Quadratic residue diffuser (QRD) Primitive root diffuser (PRD) Noise barrier