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Numerical and Performance Analysis of one row Transonic Rotor with Sweep and Lean angle

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Journal of Thermal Science 2014年第5期23卷 438-445页

作者： seyed Reza razavi Masoud Boroom Aerospace Engineering Department AmirKabir University of Technology

In this study,aerodynamic behaviors of swept and leaned blades were *** and tangential blade curvatures impacts on compressor's operating parameters were analyzed separately.A commercial CFD program which solves the Reynolds-averaged Navier-Stokes equations was used to find out the mentioned impact and the complicated flow field of transonic *** CFD method that was used for solving flow field's equation was validated by experimental data of NASA Rotor *** results showed that the compressor with curved rotors had higher efficiency,rotor pressure ratio and stable operating range compared to the compressor with un-curved *** curved rotors mostly had higher impact on the overall stable operating range compared to the other operating *** range involves choking point and stall point that were changed separately by using of bended *** finding the detailed impact of sweep and lean angle on transonic blades,various forms of lean and sweep angles were exerted to basic *** was found that sweep angles increased overall operating range up to 30%,efficiency up to 2%and pressure ratio up to 1%.Leaning the blades increased the safe operating range,the pressure ratio and efficiency by 14%,4%and 2%respectively.

关键词： compressor performance efficiency stable operational range surge improvement swept Rotor leaned rotor

Experimental investigation of the application of Eucalyptus bark to prevent lost circulation in pay zones with acid dissolution capability

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Petroleum 2021年第2期7卷 152-159页

作者： Mostafa Sedaghatzadeh Khalil Shahbazi Peyman Pourafshary seyed Ali razavi National Iranian Drilling Company Ahvaz90161635Iran Petroleum University of Technology Abadan***Iran School of Mining and Geoscience Nazarbayev UniversityNur-Sultan010000Kazakhstan

Loss of drilling fluid is a common problem during the drilling of wells and it restricts the appropriate functionality of *** fluid loss significantly increases drilling costs and non-productive time as well as the drilling operation *** investigations have been carried out in order to find appropriate mud additives that either block fractures and pores or reduce fluid loss by improving the fluid ***,environmentally friendly and effective additives are still required by the drilling ***,the application of available materials in each region,to produce appropriate additives,is a challenge for the oil *** this study,Eucalyptus Camaldulensis(EUC)bark powder has been chosen as a new,fibrous,cheap,environmentally friendly and available material to control fluid loss,particularly in southern *** characterization tests,such as acid dissolution and fluid loss control,were carried out to study the performance of the new proposed *** by hydrochloric acid and sulfuric acid were studied at various acid concentrations and *** fluid loss was also measured at different EUC *** study showed that EUC powder can reduce the final fluid loss by 88-97%,the initial fluid loss by 45-66%,and the total loss by 87e94%,which is a satisfactory level.

关键词： Eucalyptus bark Lost circulation Acid solubility Drilling mud Fluid loss

Comprehensive power swing detection by current signal modeling and prediction using the GMDH method

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Protection and Control of Modern Power Systems 2021年第1期6卷 204-214页

作者： seyed Amir Hosseini Behrooz Taheri Hossein Askarian Abyaneh Farzad razavi Department of Electrical Engineering Golpayegan University of TechnologyIsfahanIran Faculty of Electrical Biomedical and Mechatronics EngineeringQazvin BranchIslamic Azad UniversityQazvinIran Department of Electrical Engineering Amirkabir University of TechnologyTehranIran

Power swing is an undesirable variation in power flow. This can be caused by large disturbances in demand load, switching, disconnection or reclosing lines. This phenomenon may enter the zones of distance relays and cause relay malfunction leading to the disconnection of healthy lines and undermining network reliability. Accordingly, this paper presents a new power swing detection method based on the prediction of current signal with a GMDH (Group Method of Data Handling) artificial neural network. The main advantage of the proposed method over its counterparts is the immunity to noise effect in signals. In addition, the proposed method can detect stable, unstable, and multi-mode power swings and is capable of distinguishing them from the variety of permanent faults occurring simultaneously. The method is tested for different types of power swings and simultaneous faults using DIgSILENT and MATLAB, and compared with some latest power swing detection methods. The results demonstrate the superiority of the proposed method in terms of response time, the ability to detect power swings of different varieties, and the ability to detect different faults that may occur simultaneously with power swings.

关键词： Power swing Distance relay Power system protection GMDH

Characterization and corrosion behavior of Al-Co-rare earth(Ce-La)amorphous alloy

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Journal of Rare Earths 2023年第5期41卷 771-779,I0006页

作者： seyed Ali Mousavi Sayed Hamid Hashemi Ali Ashrafi Reza Shoja razavi Seyyed Mehdi Ghazi Mirsaeed Faculty of Materials and Manufacturing Technologies Malek Ashtar University of TechnologyTehran167885611Iran Department of Materials Engineering Malek Ashtar University of TechnologyIsfahanShahin-shahrIran Department of Materials Engineering Isfahan University of TechnologyIsfahan***Iran

A new Al-based amorphous alloy with excellent corrosion resistance and high thermal stability was produced in the Al-Co-RE(Ce-La)*** this regard,two different amorphous-nanocrystalline ribbons:Al_(87.6)-Co_(6.4)-Ce_(3.8-)La_(2.2)(M_(1))and Al_(82.3)-Co_(10.1)-Ce_(4.8)-La_(2.8)(M_(2))were prepared using melt *** results reveal the supercooled liquid region(ATx)of 218℃which shows that the M2alloy has higher thermal stability in comparison to the *** M2ribbons present the superior corrosion resistance because of the formation of amorphous *** icorr,Ecorr,Epit,and Epit-Ecorrvalues of fully amorphous Al-Co-Ce-La metallic ribbons have a better trend of anti-corrosion performance compared to other crystalline and amorphous aluminum alloys.

关键词： Amorphous alloys Melt-spinning Rare earth metal Corrosion behavior

Evaluation of hydrogen effect on the fatigue crack growth behavior of medium-Mn steels via in-situ hydrogen plasma charging in an environmental scanning electron microscope

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Journal of Materials Science & Technology 2021年第26期85卷 30-43页

作者： Di Wan Yan Ma Binhan Sun seyed Mohammad Javad razavi Dong Wang Xu Lu Wenwen Song Department of Mechanical and Industrial Engineering Norwegian University of Science and TechnologyRichard Birkelands vei 2B7491TrondheimNorway Steel Institute(IEHK) RWTH Aachen UniversityIntzestraße 152072AachenGermany Max-Planck-Institut für Eisenforschung GmbH Max-Planck-Straße 140237DüsseldorfGermany

Fatigue crack growth(FCG)tests were conducted on a medium-Mn steel annealed at two intercritical annealing temperatures,resulting in different austenite(γ)to fe rrite(α)phase fractions and differentγ(meta-)*** in-situ hydrogen plasma charging was combined with in-situ cyclic loading in an environmental scanning electron microscope(ESEM).The in-situ hydrogen plasma cha rging increased the fatigue crack growth rate(FCGR)by up to two times in comparison with the reference tests in *** investigations showed a brittle-like crack growth or boundary cracking manner in the hydrogen environment while a ductile transgranular manner in *** both materials,the plastic deformation zone showed a reduced size along the hydrogen-influenced fracture path in comparison with that in *** difference in the hydrogen-assisted FCG of the medium-Mn steel with different microstructures was explained in terms of phase fraction,phase stability,yielding strength and hydrogen *** refined study can help to understand the FCG mechanism without or with hydrogen under in-situ hydrogen charging conditions and can provide some insights from the applications point of view.

关键词： Hydrogen embrittlement Fatigue crack growth(FCG) Electron channeling contrast imaging(ECCI) Medium-Mn steel Hydrogen plasma

Neuro-fuzzy systems in determining light weight concrete strength

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Journal of Central South University 2019年第10期26卷 2906-2914页

作者： seyed Vahid razavi TOSEE Mehdi NIKOO Department of Civil Engineering Jundi-Shapur University of TechnologyDezfulIran Young Researchers and Elite Club Ahvaz BranchIslamic Azad UniversityAhvazIran

The adaptive neuro-fuzzy inference systems(ANFIS)are widely used in the concrete *** this research,the compressive strength of light weight concrete was *** this end,the scoria percentage and curing day variables were used as the input parameters,and compressive strength and tensile strength were used as the output *** addition,100 patterns were used,70%of which were used for training and 30%were used for *** assess the precision of the neuro-fuzzy system,it was compared using two linear regression *** comparisons were carried out in the training and testing *** results revealed that the neuro-fuzzy systems model offers more potential,flexibility,and precision than the statistical models.

关键词： neuro-fuzzy systems compressive strength light weight concrete linear regression model

SYNTHESIS AND CHARACTERIZATION OF NANOSTRUCTURED-SEGMENTED BLOCK COPOLYETHERAMIDE BASED ON NYLON6 AND POLY(ETHYLENE OXIDE)

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Chinese Journal of Polymer Science 2010年第4期28卷 597-605页

作者： Majid Peyravi Masoomeh Akhfash Ardestani Ali Akbar Babaluo Mir Karim razavi Aghjeh seyed Roohollah Pishghadam Elham Jannatdoust Nanostructure Materials Research Center(NMRC) Sahand University of TechnologyP.O.Box 51335/1996TabrizI.R.Iran Chemical Engineering Department Sahand University of TechnologyP.O.Box 51335/1996TabrizI.R.Iran Institute of Polymeric Materials Sahand University of TechnologyP.O.Box 51335/1996TabrizI.R.Iran Polymer Engineering Department Sahand University of TechnologyP.O.Box 51335/1996TabrizI.R.Iran

Segmented block copolymer based on nylon6 （N6） and polyethylene oxide （PEO） with stochiometric ratio was synthesized via a two-step process. The first step represents end capping of N6 in the presence of adipic acid leading to carboxy terminated N6, and the second one is polycondensation of the latter product with PEO in the presence of catalyst and thermostabilizer to form a high molecular weight multi-block copolymer. Several methods were applied to characterize the synthesized copolyrner such as Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, differential thermal analysis, differential scanning calorimetry, X-ray diffraction and atomic force microscopy. The obtained results confirmed the multi-block structure for copolymer with a very high degree of micro-phase separation. Atomic force microscopy micrographs indicated that the morphology was the dispersion of high stiffness nanostructured polyamide （PA） domains in the amorphous region of PEO matrix, which can be very important in their performance for membrane processes.

关键词： Copolyetheramide Segmented block Nylon6 Poly(ethylene oxide) Nanomaterial

Impact of Artificial Compressibility on the Numerical Solution of Incompressible Nanofluid Flow

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Computers, Materials & Continua 2023年第3期74卷 5123-5139页

作者： Tohid Adibi Shams Forruque Ahmed seyed Esmail razavi Omid Adibi Irfan Anjum Badruddin Syed Javed Department of Mechanical Engineering University of BonabBonabIran Science and Math Program Asian University for WomenChattogram4000Bangladesh School of Mechanical Engineering University of TabrizTabrizIran Energy Management Group Energy and Environment Research CenterNiroo Research InstituteTehranIran Mechanical Engineering Department College of EngineeringKing Khalid UniversityAbha61421Saudi Arabia

The numerical solution of compressible flows has become more prevalent than that of incompressible *** the help of the artificial compressibility approach,incompressible flows can be solved numerically using the same methods as compressible *** artificial compressibility scheme is thus widely used to numerically solve incompressible Navier-Stokes *** numerical method highly depends on its accuracy and speed of *** the artificial compressibility approach is utilized in several numerical simulations,the effect of the compressibility factor on the accuracy of results and convergence speed has not been investigated for nanofluid flows in previous ***,this paper assesses the effect of this factor on the convergence speed and accuracy of results for various types of *** improve the stability and convergence speed of time discretizations,the fifth-order Runge-Kutta method is applied.A computer program has been written in FORTRAN to solve the discretized equations in different Reynolds and Grashof numbers for various *** results demonstrate that the artificial compressibility factor has a noticeable effect on the accuracy and convergence rate of the *** optimum artificial compressibility is found to be between 1 and *** findings can be utilized to enhance the performance of commercial numerical simulation tools,including ANSYS and COMSOL.

关键词： Navier-Stokes equations incompressible flow artificial compressibility convergence rate convection flow

Evaluation of diffusion and phase transformation at Ag/Al bimetal produced by cold roll welding

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Transactions of Nonferrous Metals Society of China 2012年第2期22卷 312-317页

作者： Hossein OLIA Mehrdad ABBASI seyed Hossein razavi Material Science and Engineering Department Islamic Azad UniversityKaraj BranchP.O.Box 31485-313KarajIran Metallurgical Engineering Department Iran University of Science and TechnologyP.O.Box 31485-313NarmakTehranIran

Aluminum and silver strips were cold welded by rolling and a bimetallic strip was produced. To create cold weld between A1 and Ag, mating surfaces were specially prepared and various rolling thickness reductions were applied. The minimum critical thickness reduction to begin cold weld was specified as 70% which equals 0.1630 critical rolling shape factors. The bimetallic strips were treated by diffusion annealing at 400 ~C and various annealing time. The A1/Ag interface of strips was observed by scanning electron microscope to investigate the formation of hard and brittle probable phases. The effect of anneal time on diffusion distance and phase transformation was also analysed by EDS analysis and line scan. A diffusion region along the interface in the Ag side was observed and its width increased with prolonging annealing time. Some 8 phases were detected close to the interface after anneal treating for 3 h and 8 phase was thicker and more continuous by increasing annealing time. The microhardness measurement showed that in spite of formation of 8 phase due to diffusion annealing, the interface hardness was reduced.

关键词： Ag/A1 bimetallic strip cold weld anneal multilayer composite sheet shape factor