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Heat transfer enhancement of finned shell and tube heat exchanger using Fe_(2)O_(3)/water nanofluid

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Journal of Central South University 2021年第11期28卷 3297-3309页

作者： afshari faraz SÖZEN Adnan KHANLARI Ataollah TUNCER Azim Doğuş Department of Mechanical Engineering Erzurum Technical UniversityErzurumTurkey Department of Energy Systems Engineering Gazi UniversityAnkaraTurkey Department of Mechanical Engineering Faculty of EngineeringTarsus UniversityMersinTurkey Department of Energy Systems Engineering Burdur Mehmet Akif Ersoy UniversityBurdurTurkey Natural and Applied Science Institute Gazi UniversityAnkaraTurkey

Heat transfer mechanisms and their thermal performances need to be comprehensively studied in order to optimize efficiency and minimize energy *** nanoparticles in the base fluid are investigated to upgrade the thermal performance of heat *** this numerical study,a finned shell and tube heat exchanger has been designed and different volume concentrations of nanofluid were tested to determine the effect of utilizing nanofluid on heat ***_(2)O_(3)/water nanofluids with volume concentration of 1%,1.5% and 2% were utilized as heat transfer fluid in the heat exchanger and the obtained results were compared with pure *** Fluent software as a CFD method was employed in order to simulate the mentioned *** simulation results indicated the successful utilization of nanofluid in the heat ***,increasing the ratio of Fe_(2)O_(3) nanoparticles caused more increment in thermal energy without important pressure ***,it was revealed that the highest heat transfer rate enhancement of 19.1% can be obtained by using nanofluid Fe_(2)O_(3)/water with volume fraction of 2%.

关键词： heat transfer enhancement nanofluid shell and tube heat exchanger Fe_(2)O_(3)

Experimental investigation of effect of refrigerant gases,compressor lubricant and operating conditions on performance of a heat pump

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Journal of Central South University 2021年第11期28卷 3556-3568页

作者： afshari faraz SÖZEN Adnan KHANLARI Ataollah TUNCER Azim Doğuş ALI Hafiz Muhammad Department of Mechanical Engineering Erzurum Technical UniversityErzurumTurkey Department of Energy Systems Engineering Gazi UniversityAnkaraTurkey Department of Mechanical Engineering Faculty of EngineeringTarsus UniversityMersinTurkey Department of Energy Systems Engineering Burdur Mehmet Akif Ersoy UniversityBurdurTurkey Natural and Applied Science Institute Gazi UniversityAnkaraTurkey Mechanical Engineering Department King Fahd University of Petroleum and MineralsDhahran 31261Saudi Arabia Interdisciplinary Research Center for Renewable Energy and Power Systems(IRC-REPS) King Fahd University of Petroleum and MineralsDhahran 31261Saudi Arabia

In the field of heat pumps,there are a number of parameters that affect the performance and efficiency of the apparatus,which have been the subject of studies by individual researchers in the *** study describes an experimental method in order to investigate the effects of some significant parameters on heat pump *** this regard,a laboratory heat pump setup has been utilized to operate in different working conditions for achieving an appropriate estimation to find out effects of mentioned parameters such as refrigerant type and charge amount,compressor oil viscosity,compressor cooling fan,secondary fluids temperature and flow *** refrigerants have been selected and used as circulating fluid in the installed heat *** this work has been devoted to a detailed attempt to recognize the effects of various parameters on the coefficient of performance(COP) value,an appropriate method has been carried out to survey the obtained results by using economic *** was revealed that one of the main parameters is refrigerant charge amount which has a notable effect on *** temperature of the heat source was also tested and the performance of the system increased by more than 11% by employing mentioned modifications and various operating *** addition,by selecting a low viscosity compressor oil,the system performance increased by 18%.This improvement is more than 6% for the case that cooling fan is installed to cool the compressor element.

关键词： heat pump efficiency coefficient of performance(COP) performance compressor oil charge amount

Electronic and thermoelectric properties of YbMg_(2)X_(2)(X=P,As,Sb,Bi)zintl compounds by first-principles method

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Journal of Rare Earths 2024年第1期42卷 147-154,I0006页

作者： Sajid Khan Dil faraz Khan R.Neffati Tariq Usman Muhammad Waqar Ahsraf Shamim Khan Saeed Ullah Jan G.Murtaza Department of Physics University of Science&Technology BannuBannu28100Pakistan Department of Physics Faculty of ScienceKing Khalid UniversityP.O.Box 9004AbhaSaudi Arabia Laboratoire de Physique de La Matiere Condensee Departement de PhysiqueFaculte des Sciences de TunisUniversite Tunis El ManarCampus Universitaire1060TunisTunisia Department of Physics Shaoxing UniversityShaoxing312000China Department of Mathematics&Natural Sciences Prince Mohammad Bin Fahd UniversityAlkhobar31952Saudi Arabia Materials Modeling Lab Department of PhysicsIslamia College Peshawar25120KhyberPakhtunkhwaPakistan

In this work the structural,electronic and thermoelectric properties of YbMg_(2)X_(2)(X=P,As,Sb,Bi)zintl compounds were investigated comprehensively using first principles *** electronic properties were studied using PBE GGA,TB-mBJ and hybrid(YS-PBE0)*** the structural parameters of optimized structures are in harmonious agreement to the available *** band structure study illustrates that the titled materials manifest metallic and semi metallic nature using PBE and TB-mBJ potentials while they show wide band gap semiconducting behavior by following hybrid(YS-PBE0)*** density of states(TDOS)and partial density of states(PDOS)were also calculated to glimpse the contribution of orbitals of atoms in the formation of *** properties were studied by using BoltzTraP2 code employed to *** get enormous values of Seebeck coefficient(S),power factor(PF)and thermoelectric figure of merit(ZT)for all the samples YbMg_(2)X_(2)(X=P,As,Sb,Bi),Moreover,the overwhelming transport properties for the titled compounds indicate the optimum level of carriers’concentration which pinpoints these materials to be better thermoelectrics in the 1-2-2 zintl family.

关键词： Zintl compounds Hybrid functional Band structure Thermoelectrics Rare earths

High Velocity Compaction of Aluminum Powders

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稀有金属材料与工程 2011年第S3期40卷 86-89页

作者： Khan Dil faraz University of Science and Technology Beijing

High velocity compaction process of atomized Al powders was studied. The green density, the maximal force and the withdraw force of specimen were investigated. The green density of atomized aluminum powder was obtained to be 2.68 g/cm3 and its relative density is about 99%. The maximal force increased proximately linearly with the compaction energy. The withdraw force was observed ranging between 30 and 70 kN. The radial spring back was less than 0.1%.

关键词： high velocity compaction powder metallurgy aluminum powder

Effect of ultrasonic assisted friction stir welding on microstructure and mechanical properties of AZ91-C magnesium alloy

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Transactions of Nonferrous Metals Society of China 2019年第12期29卷 2514-2522页

作者： faraz BARADARANI Amir MOSTAFAPOUR Maghsoud SHALVANDI Faculty of Mechanical Engineering University of Tabriz

The influence of ultrasonic vibrations on microstructure and mechanical properties of the AZ91-C magnesium alloy after ultrasonic assisted friction stir welding(UaFSW)in comparison with conventional friction stir welding(FSW)was *** FSW was applied at the rotational speed of 1400 r/min and welding speed of 40 mm/min and no defects were *** the same welding parameters,the process was carried out with inducing ultrasonic vibrations to the weld line at the amplitude of 15μ*** microstructure of the specimens was observed with optical and scanning electron *** results indicate that a very fine microstructure is obtained in UaFSW with respect to that of conventional ***,β-Mg17Al12 coarse dendrites are segregated to very fine and partly spherical particles that homogeneously distribute inα-Mg *** remarkably-modified morphology of microstructure attributed to severe plastic deformation comes from ultrasonic vibration and friction stirring *** and hardness tests were performed to evaluate the mechanical properties of the *** to the results,the vibration greatly improves the mechanical properties of the conventional FSW *** tensile strength and hardness are increased from 195 MPa and HV 79 in conventional FSW to 225 MPa and HV 87 in UaFSW,respectively.

关键词： ultrasonic assisted friction stir welding AZ91 magnesium alloy microstructure mechanical properties

Lattice parameters of Ti–4Al–2V alloy with thermal oxidation

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Rare Metals 2016年第2期35卷 149-153页

作者： faraz Omidbakhsh Ali Reza Ebrahimi Department of Mechanical Engineering Tabriz Branch Islamic Azad University Mining and Metallurgical Engineering Department Amirkabir University of Technology

In this study, the effect of thermal oxidation on the lattice parameters of Ti-4Al-2V alloy was *** were oxidized at 450, 600 and 650 °C for 1-7 h in electric furnace under air atmosphere. The lattice parameters were determined using the Cohen method as a function of oxidation time at each temperature. The lattice parameters of as-received alloy are calculated as a = 0.29289 nm and c = 0.46652 nm. The thermal oxidation at 450 °C results in a gradual increase in a-parameter, whereas it goes through a maximum at higher temperatures（600 and 700 °C）. The results show that these maximums are reduced to an approximately constant value after a long-time oxidation. The c-parameter generally increases over the whole treatment condition. It is believed that these variations could be due to the dissolution of oxygen atoms in octahedral sites of hcp lattice of titanium.

关键词： Lattice parameter Ti-4Al-2V X-ray diffraction Cohen method Octahedral sites

Thin Film Flow of a Second Grade Fluid over a Stretching/Shrinking Sheet with Variable Temperature-Dependent Viscosity

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Chinese Physics Letters 2010年第3期27卷 212-215页

作者： S. Nadeem Naeem faraz Department of Mathematics Quaid-i-Azam University 45320 Islamabad Pakistan

Effects of variable viscosity on the flow and heat transfer in a thin film on a horizontal porous stretching sheet are analyzed. The steady boundary layer equations for momentum and thermal energy are simplified by using similarity transformations. The resulted and coupled nonlinear differential equations are solved by Homotopy analysis method. The results are presented graphically to interpret various physical parameters appearing in the problem.

关键词： Soft matter liquids and polymers Fluid dynamics Mathematical physics

A multi-layered policy generation and management engine for semantic policy mapping in clouds

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Digital Communications and Networks 2020年第1期6卷 38-50页

作者： faraz Fatemi Moghaddam Philipp Wieder Ramin Yahyapour Gesellschaft für wissenschaftliche Datenverarbeitung mbH Gottingen(GWDG) Germany Institute of Informatics Georg-August-UniversitatGottingenGermany

The long awaited cloud computing concept is a reality now due to the transformation of computer ***,security challenges have become the biggest obstacles for the advancement of this emerging technology.A well-established policy framework is defined in this paper to generate security policies which are compliant to requirements and ***,a federated policy management schema is introduced based on the policy definition framework and a multi-level policy application to create and manage virtual clusters with identical or common security *** proposed model consists in the design of a well-established ontology according to security mechanisms,a procedure which classifies nodes with common policies into virtual clusters,a policy engine to enhance the process of mapping requests to a specific node as well as an associated cluster and matchmaker engine to eliminate inessential mapping *** suggested model has been evaluated according to performance and security parameters to prove the efficiency and reliability of this multilayered engine in cloud computing environments during policy definition,application and mapping procedures.

关键词： Cloud computing Security Security management Policy management Access control Policy mapping

Evaluation of CRU TS, GPCC, AgMERRA, and AgCFSR meteorological datasets for estimating climate and crop variables: A case study of maize in Qazvin Province, Iran

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Journal of Arid Land 2022年第12期14卷 1361-1376页

作者： faraz GORGIN PAVEH Hadi RAMEZANI ETEDALI Brian COLLINS Syracuse University Syracuse 13244USA Imam Khomeini International University Qazvin 34149-16818Iran Centre for Crop Science The University of QueenslandBrisbane 4072Australia

In the past few decades,meteorological datasets from remote sensing techniques in agricultural and water resources management have been used by various researchers and *** on the literature,meteorological datasets are not more accurate than synoptic stations,but their various advantages,such as spatial coverage,time coverage,accessibility,and free use,have made these techniques superior,and sometimes we can use them instead of synoptic *** this study,we used four meteorological datasets,including Climatic Research Unit gridded Time Series(CRU TS),Global Precipitation Climatology Centre(GPCC),Agricultural National Aeronautics and Space Administration Modern-Era Retrospective Analysis for Research and Applications(AgMERRA),Agricultural Climate Forecast System Reanalysis(AgCFSR),to estimate climate variables,i.e.,precipitation,maximum temperature,and minimum temperature,and crop variables,i.e.,reference evapotranspiration,irrigation requirement,biomass,and yield of maize,in Qazvin Province of Iran during *** first,data were gathered from the four meteorological datasets and synoptic station in this province,and climate variables were ***,after using the AquaCrop model to calculate the crop variables,we compared the results of the synoptic station and meteorological *** the four meteorological datasets showed strong performance for estimating climate *** and AgCFSR had more accurate estimations for precipitation and maximum ***,their normalized root mean square error was inferior to CRU for minimum ***,they were all very efficient for estimating the biomass and yield of maize in this *** reference evapotranspiration and irrigation requirement CRU TS and GPCC were the most efficient rather than AgMERRA and *** for the estimation of biomass and yield,all the four meteorological datasets were *** sum up,GPCC and AgCFSR were the two best datasets in thi

关键词： climate variables crop variables meteorological datasets precipitation reference evapotranspiration irrigation requirement Iran