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Erosion and erosion-corrosion of Al-brass alloy: Effects of jet velocity, sand concentration and impingement angle on surface roughness

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Transactions of Nonferrous metals Society of China 2017年第11期27卷 2371-2380页

作者： morteza ABEDINI Hamid m.ghasemi School of metallurgy and materials Engineering College of EngineeringUniversity of Tehran Department of metallurgy and materials Engineering University of Kashan

Effects of jet velocity,sand concentration and impingement angle on the surface roughness of Al-brass alloy were investigated after erosion and erosion?corrosion *** tests were performed using a jet impingement *** eroded surfaces were characterized using2-D and3-D surface profilometery and scanning electron microscopy(SEm).The results showed that there was an increase in the surface roughness of the erosion?corrosion samples as sand concentration was increased to1,5and10g/L at jet velocities of9,6and3m/s,***,the surface roughness decreased with a further increase in sand *** decrease in the surface roughness was attributed to the higher work hardening of the surface,rebounding or blanketing effect and very high frequency of the impacts at the higher sand *** surface roughness increased as the jet velocity *** results also showed that the change in the surface roughness with impingement angle was not significant at two jet velocities of3and6m/***,at a higher jet velocity of9m/s,formation of ripples on the erosion surfaces at oblique angles resulted in a higher surface roughness as compared with the normal impingement angle.

关键词： Al-brass erosion.corrosion surface topography sand concentration

Numerical methods for solving singular integral equations obtained by fracture mechanical analysis of cracked wedge

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Applied mathematics and mechanics(English Edition) 2014年第3期35卷 311-324页

作者： m.GHADIRI H.ghasemi Faculty of Engineering and Technology Department of Mechanical EngineeringImam Khomeini International University

The numerical solutions to the singular integral equations obtained by the fracture mechanical analyses of a cracked wedge under three different conditions are considered. The three considered conditions are:(i) a radial crack on a wedge with a nonfinite radius under the traction-traction boundary condition,(ii) a radial crack on a wedge with a finite radius under the traction-traction boundary condition, and(iii) a radial crack on a finite radius wedge under the traction-displacement boundary condition. According to the boundary conditions, the extracted singular integral equations have different forms. Numerical methods are used to solve the obtained coupled singular integral equations, where the Gauss-Legendre and the Gauss-Chebyshev polynomials are used to approximate the responses of the singular integral equations. The results are presented in figures and compared with those obtained by the analytical response. The results show that the obtained Gauss-Chebyshev polynomial response is closer to the analytical response.

关键词： fracture mechanics numerical analytical singular integral equation Gauss-Legendre

Practical optimization of deployable and scissor-like structures using a fast GA method

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Frontiers of Structural and Civil Engineering 2019年第3期13卷 557-568页

作者： m.SALAR m.R.ghasemi B.DIZANGIAN Department of Civil Engineering University of Sistan and BaluchestanZahedanIran Department of Civil Engineering Velayat UniversityIranshahrIran

This paper addresses practical sizing optimization of deployable and scissor-like structures from a new point of *** structures have been recently highly regarded for beauty,lightweight,determine behavior,proper performance against lateral loads and the ability of been compactly *** this time,there is a few studies done considering practical optimization of these *** considered here includes wind and gravity *** foldable scissor-like structures,connections have a complex *** this reason,in this study,the authors used the ABAQUS commercial package as an analyzer in the optimization *** made the obtained optimal solutions highly reliable from the point of view of applicability and construction ***,to do optimization task,a fast genetic algorithm method,which has been recently introduced by authors,was *** results show that despite less weight for aluminum models than steel models,aluminum deployable structures are not affordable because they need more material than steel structures and cause more environmental damage.

关键词： optimization scissor-like structures deployable structures genetic algorithm ABAQUS

Theoretical investigation of micropolar fluid flow between two porous disks

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Journal of Central South University 2015年第7期22卷 2825-2832页

作者： P.Valipour S.E.ghasemi m.Vatani Department of Textile and Apparel Qaemshahr Branch Islamic Azad University Young Researchers and Elite Club Qaemshahr Branch Islamic Azad University Department oaf mechanical Engineering Babol University of Technology

The steady, laminar, incompressible and two dimensional micropolar flow between two porous disks was investigated using optimal homotopy asymptotic method(OHAm) and fourth order Runge–Kutta numerical method. Comparison between OHAm and numerical method shows that OHAm is an exact and high efficient method for solving these kinds of problems. The results are presented to study the velocity and rotation profiles for different physical parameters such as Reynolds number, vortex viscosity parameter, spin gradient viscosity and microinertia density parameter. As an important outcome, the magnitude of the microrotation increases with an increase in the values of injection velocity while it decreases by increasing the values of suction velocity.

关键词： theoretical investigation porous disks micropolar fluid flow optimal homotopy asymptotic method(OHAm) microrotation

KINETIC mODELING OF ESTERIFICATION OF EPOXY RESIN IN THE PRESENCE OF TRIPHENYLPHOSPHINE FOR PRODUCING VINYL ESTER RESIN: mECHANISTIC RATE EQUATION

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Chinese Journal of Polymer Science 2006年第6期24卷 599-608页

作者： m. Rafizadeh H. ghasemi V. Haddadi-Asl Polymer Engineering Department Amirkabir University of TechnologyP. O. Box 15785-4414TehranIran

Due to its mechanical properties and ease of use, vinyl ester resin is enjoying increasing consideration. This resin normally is produced by reaction between epoxy resin and unsaturated carboxylic acid. In the present study, bis-phenol A based epoxy resin and methacrylic acid was used to produce vinyl ester resin. The reaction was conducted under both stoichiometric and non-stoichiometric conditions in the presence of triphenylphosphine as catalyst. The stoichiometric and non-stoichiometric experiments were conducted at 95, 100, 105 and 110℃ and at 90 and 95℃, respectively. The first order rate equation and mechanism based rate equation were examined. Parameters are evaluated by least square method. A comparison of mechanism based rate equation and experimental data show an excellent agreement. Finally, Arrhenius equation and activation energy were presented.

关键词： Esterification Epoxy resin Vinyl ester resin Kinetic Rate equation.

Effect of Catalyst on the Formation of Silica Coating on Nickel Substrate by Sol-Gel Processing

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材料热处理学报 2004年第05B期25卷 1295-1298页

作者： Ali ghasemi F.Ashrafizadeh m.A.Golozar AH Ashrafi materials Engineering Department Isfahan University of Technology Isfahan IranMaterials Engineering Department Isfahan University of Technology Isfahan IranMaterials Engineering Department Isfahan University of Technology Isfahan IranMaterials Engineering Department Isfahan University of Technology Isfahan Iran

In this research work silica coating was produced on nickel substrates by a sol-gel process. In order to increase the rate of hydrolysis and to reduce the rate of polymerization several acid catalysts including nitric acid-hydrochloric acid, acetic acid, hydrochloric acid and nitric acid were add to silica sol. Conversely, in order to control the rate of hydrolysis and to increase the rate of polymerization, basic catalyst of ammonia and ammonia hydroxyl were introduced in to the solution. Nickel specimens of known surface roughness were chemically cleaned and prepared by dipping in the sols. In order to produce a suitable silica coating the drying and firing cycles were optimized on these substrates. The structure and uniformity of the coatings produced were examined by scanning electron microscopy. Coatings composition was determined using glow discharge optical spectroscopy and EDAX microanalysis. Experimental result showed that hydrochloric acid, acetic acid, ammonia and acetic acid - ammonia are suitable catalytic agents for silica coating formation on nickel type substrate.

关键词：溶胶凝胶催化剂镍合金硅涂覆

Optimization of design parameters for controlled rocking steel braced dual-frames

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Earthquake Engineering and Engineering Vibration 2022年第4期21卷 1053-1068页

作者： Sobhan ghasemi m.Firoozi Nezamabadi Abdolreza S.moghadam mahmood Hosseini Department of Civil Engineering South Tehran BranchIslamic Azad UniversityTehranIran Structural Engineering Research Center International Institute of Earthquake Engineering and Seismology(IIEES)TehranIran

A controlled rocking concentrically steel braced frame(CR-CSBF)is introduced as an alternative to conventional methods to prevent major structural damage during large *** is equipped with elastic post-tensioned(PT)cables and replaceable devices or fuses to provide overturning resistance and dissipate energy,*** CR-CSBFs are not officially legalized in globally valid codes for new buildings,it is expected to be presented in them in the near *** main goal of this study is to determine the optimal design parameters consist of the yield strength and modulus of elasticity of the fuse,the initial force of the PT cable,and the gravity load on the rocking column,considering different heights of the frame,spanning ratios and ground motion types for dual-configuration *** time-history analyses are performed in *** study aims to define the optimal input variables as effective design parameters of CR-CSBFs by comparing four seismic responses consisting of story drift,roof displacement,roof acceleration and base shear,and also using the Euclidean metric optimization *** the previous research,this study is innovative and first of its *** results demonstrate that the optimal design parameters are variable for various conditions.

关键词： self-centering rocking steel braced frame design parameters optimization low damage

Effect of Pyrrole and N-methylpyrrole Coatings on Corrosion Resistance of mild Steel

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材料热处理学报 2004年第05B期25卷 1137-1141页

作者： Ali Ashrafi m.A.Golozar S.mallakpour Ali ghasemi Department of materials Engineering Isfahan University of Technology Isfahan 84154 Iran Organic Polymer Chemistry Research Laboratory College of Chemistry Isfahan University of Technology Isfahan 84156 Iran

Electrochemical polymerizations of various ratios of pyrrole and methylpyrrole monomers were performed in aqueous toluene-4-sulfinic acid sodium salt (T4SNa) electrolyte, using galvanostatic method. pH of electrolyte was adjusted by p-toluene sulfonic acid (PTSA). In order to prevent corrosion of mild steel substrates during coating deposition, specimens were pretreated in 0.5m oxalic acid solution, employing galvanostatic method. This would passivate the steel substrate and facilitate the coating process as well. Corrosion resistance of coated substrates was investigated in 1m NaCl solution using Tafel polarization technique. In addition, using scanning electron microscopy (SEm), morphological characterization of coatings produced, was investigated. Regarding the corrosion characteristics, results obtained revealed that the ratio of 1 to 1 (Pyrrole/methylpyrrole) could play an important role.

关键词：导电聚合物电引发聚合吡咯耐蚀性低碳钢

Efficient approaches of determining the motion of a spherical particle in a swirling fluid flow using weighted residual methods

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Particuology 2015年第6期13卷 68-74页

作者： Seiyed E. ghasemi m. Vatani D.D. Ganji Young Researchers and Elite Club Qaemshahr Branch Islamic Azad University Qaemshahr lran Department of mechanical Engineering Babol University of Technology Babol lran

The motion of a spherical particle released in a swirling fluid flow is studied employing the least-squares method and method of moments. The governing equations are obtained and solved employing the two methods. The accuracy of the results is examined against the results of a fourth-order Runge-Kutta numer- ical method. The effects of various parameters, namely the initial radius, initial radial velocity, initial angular velocity, and drag-to-inertia ratio, on the non-dimensional velocity profiles and particle position distribution are considered. The results show that the radial velocity increases over time while the angular velocity decreases, and that an increase in the initial radial velocity increases the particle radial distance and angular velocity but decreases the radial velocity profile.

关键词： Spherical particle Swirling flow Radial velocity Angular velocity Least-squares method method of moments