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    Thermal-aware Accelerator Placement and Task Assignment for Energy Improvement in Data Center

    , M.Sc. Thesis Sharif University of Technology Kazemi Abharian, Sanaz (Author) ; Goudarzi, Maziar (Supervisor)
    Abstract
    With the proliferation of data centers, their ever-growing energy consumption has gained lots of attention from both academy and industry . Two primary parts that use majority of energy in data centers are IT equipment and cooling system or Computing Room Air Conditioning (CRAC) unit. Energy consumption of cooling system strongly relies on thermal performance of data center. Therefore, applying thermal management techniques for decreasing energy consumption of CRAC is a common practice. Moreover, the energy consumption of IT equipment affects the energy consumption of CRAC directly. Demand for more computing resources in data centers and their physical limits has, motivated the use of FPGAs ... 

    Thermal Relaxation Time Of Healthy and Cancerous Tissue In Pulsed Laser Using Monte Carlo Simulation

    , M.Sc. Thesis Sharif University of Technology Khaze, Mehran (Author) ; Amjadi, Ahmad (Supervisor)
    Abstract
    Thermal relaxation time is the time when maximum temperature of a particle get to 1/e of it’s initial value. The destruction of a tissue depends to this important parameter. This parameter has studied by Monte Carlo simulation of pulsed laser in to environment as healthy and cancerous tissue. The main goal of this method is providing proper temperature in a special area so that minimize thermal destruction around that area. In this thesis, temperature distribution of tissue that is caused by pulsed laser, has solved by new method;in this new method the pulse duration uses for Monte Carlo simulation. Also using the solution of radiation transfer equation by Discretes Ordinate Method, new... 

    Optimal Design of Tolerances in the Non-rigid Assemblies under the Thermal Impact

    , M.Sc. Thesis Sharif University of Technology Hemati Nik, Javad (Author) ; Khodaygan, Saeed (Supervisor)
    Abstract
    Tolerance allocation in the recent mechanical assembly is significant because it straightly affects product performance and cost. Loose tolerances may cause the quality defect while tight tolerances can increase the cost. Thermal effects and the temperature gradients are one of the factors that caused changes in the size and geometry of the components during the performance of mechanical assemblies. This thesis proposes a new approach for tolerance design considering the thermal effects, to achieve lower manufacturing cost and good product quality. Finite element analysis is used to determine the deformation of components in an assembly. The neural network is trained using experimental... 

    Development of consistent Thermomechanical ALE Formulation with Application to Simulation of Machining

    , Ph.D. Dissertation Sharif University of Technology Tadi Beni, Yaghob (Author) ; Movahhedy, Mohammd Reza (Supervisor) ; Farrahi, Hossein (Supervisor)
    Abstract
    Accurate description of kinematics of continuum mechanics is essential in simulation of large deformation problems in solid mechanics. From the numerical viewpoint, two main approaches have been used for such description; the Lagrangian approach and the Eulerian approach. However, each of these approaches suffer from shortcomings which hinders their application in large deformation problems. A more general approach called the Arbitrary Lagrangian-Eulerian method (ALE) provides an opportunity to exploit the advantages of both Lagrangian and Eulerian approach, while avoiding their shortcoming. In an ALE analysis, the FE mesh is neither attached to the material nor fixed in space, necessarily.... 

    An investigation on the sintering behavior of high strength Al-Zn-Mg-Cu alloy prepared from elemental powders

    , Article 2006 Powder Metallurgy World Congress and Exhibition, PM 2006, Busan, 24 September 2006 through 28 September 2006 ; Volume 534-536, Issue PART 1 , 2007 , Pages 489-492 ; 02555476 (ISSN); 0878494197 (ISBN); 9780878494194 (ISBN) Shahmohammadi, M ; Sirnchi, A ; Danninger, H ; Arvand, A ; Sharif University of Technology
    Trans Tech Publications Ltd  2007
    Abstract
    In the present work, the sintering behavior of high strength Al-5.6Zn-2.5Mg-1.6Cu (in wt.%) alloy compacts was investigated. Green parts made by pressing of mixed elemental powders were sintered at different temperatures between 400 and 600°C The effect of the sintering temperature on density, dimensional change and microstructure of the Al alloy was studied. Microstructural evaluation was accompanied by XRD and DSC methods in order to determine the temperature and chemical composition of the liquid phases formed during sintering. It was found that three transient liquid phases are formed at 420, 439 and 450°C Microstructural study revealed the progressive formation of sintered contacts due... 

    Vibration of rotating functionally graded timoshenko nano-beams with nonlinear thermal distribution

    , Article Mechanics of Advanced Materials and Structures ; Volume 25, Issue 6 , 2018 , Pages 467-480 ; 15376494 (ISSN) Azimi, M ; Mirjavadi, S ; Shafiei, N ; Salem Hamouda, A. M ; Davari, E ; Sharif University of Technology
    Taylor and Francis Inc  2018
    Abstract
    The vibration analysis of rotating, functionally graded Timoshenko nano-beams under an in-plane nonlinear thermal loading is studied for the first time. The formulation is based on Eringen's nonlocal elasticity theory. Hamilton's principle is used for the derivation of the equations. The governing equations are solved by the differential quadrature method. The nano-beam is under axial load due to the rotation and thermal effects, and the boundary conditions are considered as cantilever and propped cantilever. The thermal distribution is considered to be nonlinear and material properties are temperature-dependent and are changing continuously through the thickness according to the power-law... 

    Thermo-mechanical vibration of rotating axially functionally graded nonlocal Timoshenko beam

    , Article Applied Physics A: Materials Science and Processing ; Volume 123, Issue 1 , 2017 ; 09478396 (ISSN) Azimi, M ; Mirjavadi, S. S ; Shafiei, N ; Hamouda, A. M. S ; Sharif University of Technology
    Springer Verlag  2017
    Abstract
    The free vibration analysis of rotating axially functionally graded nanobeams under an in-plane nonlinear thermal loading is provided for the first time in this paper. The formulations are based on Timoshenko beam theory through Hamilton’s principle. The small-scale effect has been considered using the nonlocal Eringen’s elasticity theory. Then, the governing equations are solved by generalized differential quadrature method. It is supposed that the thermal distribution is considered as nonlinear, material properties are temperature dependent, and the power-law form is the basis of the variation of the material properties through the axial of beam. Free vibration frequencies obtained are... 

    Efficiency of copper bioleaching of two mesophilic and thermophilic bacteria isolated from chalcopyrite concentrate of Kerman-Yazd regions in Iran

    , Article Scientia Iranica ; Volume 14, Issue 2 , 2007 , Pages 180-184 ; 10263098 (ISSN) Mousavi, S. M ; Yaghmaei, S ; Vossoughi, M ; Jafari, A ; Sharif University of Technology
    Sharif University of Technology  2007
    Abstract
    A mesophilic iron oxidizing bacterium, Acidithiobacillus ferrooxidans, has been isolated (33°C) from a typical chalcopyrite copper concentrate of the Sarcheshmeh Copper Mine in the region of Kerman located in the south of Iran. In addition, a thermophilic iron oxidizing bacterium, Sulfobacillus spp., has been isolated (60°C) from the Kooshk Lead and Zinc Mine near the city of Yazd in the mid-west region of Iran. The variation of pH, ferrous and ferric concentration and cell growth on the time and effects of some factors, such as temperature and initial ferrous concentration, on the bioleaching of chalcopyrite concentrate obtained from Sarcheshmeh Copper Mine, were investigated. Bioleaching... 

    Study of self-diffusion in two binary solutions, glycerol-water and methanol-water using diffusion-ordered spectroscopy

    , Article Scientia Iranica ; Volume 23, Issue 3 , 2016 , Pages 1175-1183 ; 10263098 (ISSN) Fadaei, E ; Tafazzoli, M ; Sharif University of Technology
    Sharif University of Technology 
    Abstract
    The concentration and temperature behaviors of the self-diffusion coefficient were analyzed in glycerol-water and methanol-water solutions using Diffusion-Ordered Spectroscopy (DOSY) experiment. Our results indicate that the self-diffusion coefficient dips with increasing concentration and decreasing temperature. The concentration behavior shows that there is hydrogen bond interaction between water and alcohol, which declines the self-diffusion coefficients of both in the aqueous binary mixtures. The self-diffusion activation energies were estimated 13.6, 29.4, and 32.8 (kJ/mol) for methanol and 24.8, 25.5, and 27.6 (kJ/mol) for water in the methanol-water solutions with 0.03, 0.10, and 0.20... 

    Stress analysis of multilayer thin walled pipes with circular cut-outs

    , Article World Congress on Engineering 2016, WCE 2016, 29 June 2016 through 1 July 2016 ; Volume 2224 , 2016 , Pages 1146-1150 ; 20780958 (ISSN); 9789881404800 (ISBN) Kamalarajah, R ; Bull, J.W ; Chizari, M ; Ao S.I ; Ao S.I ; Gelman L ; Ao S.I ; Gelman L ; Hukins D.W.L ; Hunter A ; Korsunsky A.M ; et al.; IAENG Society of Artificial Intelligence; IAENG Society of Bioinformatics; IAENG Society of Computer Science; IAENG Society of Data Mining; IAENG Society of Electrical Engineering ; Sharif University of Technology
    Newswood Limited  2016
    Abstract
    A finite element analysis of a double layered shell with a circular hole is carried out with the computer aided engineering software Abaqus (Dassault Systèmes, FR). The model proposed has been used to perform a stress analysis on three pipes with different sized hole. Moreover, thermal expansion has been implemented in the testing. For the purpose of the research, the elastic properties of the materials have been considered and the results compared with the ones previously published in literature. The outcome of the investigation will benefit towards the design of optimal and sustainable pipes with circular cut outs  

    Interaction between refractory crucible materials and the melted NiTi shape-memory alloy

    , Article Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science ; Volume 36, Issue 3 , 2005 , Pages 395-403 ; 10735615 (ISSN) Sadrnezhad, S. K ; Badakhshan Raz, S ; Sharif University of Technology
    Minerals, Metals and Materials Society  2005
    Abstract
    Attempts have been made to quantify the amount of contaminants absorbed by liquid metal from commercial ZrO2-, Al2O3-, and SiC-base crucibles used for vacuum melting of Ni-45 wt pet Ti alloy. The molten alloy was held under vacuum for 90 minutes at 1450°C to become homogenized. Reactions between the liquid metal and the crucible were investigated by visual observation, chemical analysis, scanning electron microscopy (SEM) image processing, and X-ray mapping. The relative degree of contamination declined in the following sequence: commercially pure SiC > SiC-5 wt pct Al2O3-5 wt pet SiO2] > slurry cast alumina > recrystallized alumina > zircon type A > oxygen deficient high-purity zirconia.... 

    Deformation characteristics of isothermally forged UDIMET 720 nickel-base superalloy

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 36, Issue 4 , 2005 , Pages 895-905 ; 10735623 (ISSN) Monajati, H ; Jahazi, M ; Yue, S ; Taheri, A. K ; Sharif University of Technology
    Minerals, Metals and Materials Society  2005
    Abstract
    The hot deformation behavior of nickel-base superalloy UDIMET 720 in solution-treated conditions, simulating the forging process of the alloy, was studied using hot compression experiments. Specimens were deformed in the temperature range of 1000 °C to 1175 °C with strain rates of 10-3 to 1 s-1 and total strain of 0.8. Below 1100 °C, all specimens showed flow localization as shear band through the diagonal direction, with more severity at higher strain rates. A uniform deformation was observed when testing between 1100 °C and 1150 °C with dynamic recrystallization as the major flow softening mechanism above 1125 °C. Deformation above γ' solvus temperature was accompanied with grain boundary... 

    Thermal analysis of laser hardening for different moving patterns

    , Article International Journal of Engineering, Transactions A: Basics ; Volume 22, Issue 2 , 2009 , Pages 169-180 ; 17281431 (ISSN) Farrahi, G. H ; Sistaninia, M ; Sharif University of Technology
    Materials and Energy Research Center  2009
    Abstract
    Transient thermal field in laser surface hardening treatment of medium carbon steel was analyzed by employing both three-dimensional analytical model and finite element model. In finite element model the laser beam was considered as a moving plane heat flux to establish the temperature rise distribution in the work-piece, while in analytical model laser beam was considered as an internal heat source. The numerical results were compared with the analytical results. In laser heat treatment of steel some methods are used to produce a wider and nearly uniform average irradiance profile. It may be achieved by rotating the beam optically, thereby producing an overlapping spiral track, or by... 

    Modelling and simulation of syngas unit in large scale direct reduction plant

    , Article Ironmaking and Steelmaking ; Volume 30, Issue 1 , 2003 , Pages 18-24 ; 03019233 (ISSN) Farhadi, F ; Motamed Hashemi, M. Y ; Bahrami Babaheidari, M ; Sharif University of Technology
    IOM Communications Ltd  2003
    Abstract
    The production of reducing gas is usually a bottleneck to capacity increase in direct reduction plants. Modelling and simulation of reducing gas production result in better design and operation of these plants. In the present work, a mathematical model is discussed that relates to a Midrex reformer, which is different from conventional steam reformers in some respects. Both process side and furnace side have been included in an integrated model. Simulation results have been tested against available data from an actual plant. The model predictions have been found to be reasonably accurate. The effects of three process variables, feed gas temperature, feed gas pressure and excess air, on... 

    Mathematical study of probe arrangement and nanoparticle injection effects on heat transfer during cryosurgery

    , Article Computers in Biology and Medicine ; Volume 66 , Nov , 2015 , Pages 113-119 ; 00104825 (ISSN) Mirkhalili, S. M ; Ramazani S. A. A ; Nazemidashtarjandi, S ; Sharif University of Technology
    Elsevier Ltd  2015
    Abstract
    Blood vessels, especially large vessels have a greater thermal effect on freezing tissue during cryosurgery. Vascular networks act as heat sources in tissue, and cause failure in cryosurgery and reappearance of cancer. The aim of this study is to numerically simulate the effect of probe location and multiprobe on heat transfer distribution. Furthermore, the effect of nanoparticles injection is studied. It is shown that the small probes location near large blood vessels could help to reduce the necessary time for tissue freezing. Nanoparticles injection shows that the thermal effect of blood vessel in tissue is improved. Using Au, Ag and diamond nanoparticles have the most growth of ice ball... 

    Various effects of reformer gas enrichment on natural-gas, iso-octane and normal-heptane HCCI combustion using artificial inert species method

    , Article Energy Conversion and Management ; Volume 159 , March , 2018 , Pages 7-19 ; 01968904 (ISSN) Reyhanian, M ; Hosseini, V ; Sharif University of Technology
    Elsevier Ltd  2018
    Abstract
    Reformer gas (syngas) addition to main fuel is a practical solution for combustion timing control in HCCI engines. This study emphasizes the understanding of various effects of reformer gas (RG) addition, with composition of 75%vol H2 and 25%vol CO, in HCCI combustion by developing an artificial inert species method and using a detailed chemical kinetics multi-zone model. Three fuels (iso-octane, n-heptane, and natural gas) with different autoignition characteristics were used in this study. The developed multi-zone model was validated for mentioned fuels at various percentages of RG using six experimental cases of a single-cylinder CFR engine. The results showed that increasing reformer gas... 

    Gas permeability measurement in polyethylene and its copolymer films

    , Article Materials and Design ; Volume 28, Issue 9 , 2007 , Pages 2528-2532 ; 02613069 (ISSN) Gholizadeh, M ; Razavi, J ; Mousavi, S. A ; Sharif University of Technology
    Elsevier Ltd  2007
    Abstract
    In this research, low density polyethylene (LDPE) and poly(ethylene-co-vinyl acetate) (EVA) were used as polymeric materials. The methods used to produce LDPE and EVA was film blowing and thermal-dry phase inversion. The amount of permeability, diffusivity and solubility of O2 and CO2 through above polymers were obtained and also the effect of temperature, pressure and film thickness for LDPE was measured. To study film cross-section morphology in EVA, scanning electron microscopy (SEM) was applied. The results showed that the amount of permeability and solubility were decreased by increasing film thickness but diffusivity was increased. However, by increasing temperature, permeability,... 

    Optimum temperature for recovery and recrystallization of 52Ni48Ti shape memory alloy

    , Article Materials and Design ; Volume 28, Issue 6 , 2007 , Pages 1945-1948 ; 02613069 (ISSN) Sadrnezhaad, S. K ; Mirabolghasemi, S. H ; Sharif University of Technology
    Elsevier Ltd  2007
    Abstract
    Results of recent studies on the effect of heat treatment after cold rolling on mechanical properties and transformation temperatures of the cast 52Ni48Ti alloys are described. It is seen that stress-induced martensite is formed when both the as-rolled and the low-temperature (≤400 °C) heat-treated samples are strained. Martensite reorientation due to the stress action occurs in samples heat treated at 500 °C and higher. Optimum recovery occurs below 600 °C resulting in hardness reduction. Recrystallization starts at 600 °C resulting in parent phase yield stress enhancement. Yield stress starts to decrease when grain growth and order-disorder transformation both occur above 700 °C. © 2006... 

    Minimum miscibility pressure of CO2 and crude oil during CO2 injection in the reservoir

    , Article Journal of Supercritical Fluids ; Volume 127 , 2017 , Pages 121-128 ; 08968446 (ISSN) Lashkarbolooki, M ; Eftekhari, M. J ; Najimi, S ; Ayatollahi, S ; Sharif University of Technology
    Elsevier B.V  2017
    Abstract
    Recently, carbon dioxide (CO2) flooding into depleted reservoirs regardless of miscible or immiscible displacement is widely investigated not only to improve oil recovery but also to reduce the greenhouse effect of this gas produced by numbers of industries in the globe. In the light of this fact, in the first stage of this investigation, the minimum miscibility pressure (MMP) of CO2 and light crude oil (API° = 35) with low asphaltene content was determined at temperatures of 30, 50 and 80 °C using vanishing interfacial tension (VIT) method. The obtained results demonstrated that the MMP of the studied system is almost linear function of temperature with slope of 0.15 MPa/K. The interesting... 

    The effect of target annealing temperature on optical and structural properties and composition of CdS thin films prepared by pulsed laser

    , Article Optical Materials ; Volume 27, Issue 10 , 2005 , Pages 1583-1586 ; 09253467 (ISSN) Mahdavi, S. M ; Iraji Zad, A ; Tilaki, R. M ; Sharif University of Technology
    Elsevier  2005
    Abstract
    We studied the effect of target annealing temperature on optical and structural properties and composition of CdS thin films prepared by pulsed Nd:YAG laser. Deposited samples from annealed targets at 300 °C showed a mixed cubic and hexagonal structure, a band gap of about 2.56 eV and Cd/S ratio equal 1. This ratio increased to 2.40 and its band gap decreased to 2.46 eV when the sample was annealed at 500 °C for 1 h in air. However, films prepared from annealed targets at 500 °C became dark due to existence of polymorphous phase of CdO. Films changed to transparent yellow color with a hexagonal CdS structure and some peaks related to CdO after annealing above 250 °C in air. Its band gap...