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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.... 

    Phase behavior modeling of asphaltene precipitation for heavy crudes: A promising tool along with experimental data

    , Article International Journal of Thermophysics ; Vol. 33, issue. 12 , December , 2012 , p. 2251-2266 ; ISSN: 0195928X Tavakkoli, M ; Kharrat, R ; Masihi, M ; Ghazanfari, M. H ; Fadaei, S ; Sharif University of Technology
    Abstract
    Thermodynamic modeling is known as a promising tool for phase behavior modeling of asphaltene precipitation under different conditions such as pressure depletion and CO2 injection. In this work, a thermodynamic approach is used for modeling the phase behavior of asphaltene precipitation. The precipitated asphaltene phase is represented by an improved solid model, while the oil and gas phases are modeled with an equation of state. The PR-EOS was used to perform flash calculations. Then, the onset point and the amount of precipitated asphaltene were predicted. A computer code based on an improved solid model has been developed and used for predicting asphaltene precipitation data for one of... 

    Experimental study of asphaltene precipitation behavior during miscible carbon dioxide injection

    , Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Vol. 36, issue. 14 , July , 2014 , pp. 1523-1530 ; ISSN: 15567036 Alizadeh, A ; Nakhli, H ; Kharrat, R ; Ghazanfari, M. H ; Aghajani, M ; Sharif University of Technology
    Abstract
    Many reservoir and production engineers face asphaltene precipitation as a major problem during miscible carbon dioxide flooding projects. Experimental studies regarding asphaltene precipitation are therefore employed to assist in selecting appropriate facilities and proper operation schemes. During this study, a series of high pressure, high temperature experiments are designed and performed to analyze asphaltene precipitation behavior of an Iranian light reservoir crude at reservoir conditions due to natural production and miscible CO2 gas injection. For both sets of experiments, two different temperature levels (including reservoir temperature) are selected to investigate the role of... 

    Investigation of thermal effects on machining chatter based on FEM simulation of chip formation

    , Article CIRP Journal of Manufacturing Science and Technology ; Vol. 7, issue. 1 , 2014 , p. 1-10 Hajmohammadi, M. S ; Movahhedy, M. R ; Moradi, H ; Sharif University of Technology
    Abstract
    In this paper, thermo mechanical finite element analysis of orthogonal machining process with a flexible tool is carried out to study the dynamic behaviour of the machining system and its stability against chatter vibration. By combining the simulation of chip formation in metal cutting with the dynamic phenomena leading to chatter development, the influence of various phenomena, including thermal effects resulting from friction and plastic deformations on the stability of the process are investigated. The novelty of this model is in its ability to evaluate the effect of temperature rise in the cutting zone on the stability of cutting process. Process stability is analyzed and compared for... 

    Phase behavior modeling of asphaltene precipitation for heavy crudes: A promising tool along with experimental data

    , Article International Journal of Thermophysics ; Volume 33, Issue 12 , December , 2012 , Pages 2251-2266 ; 0195928X (ISSN) Tavakkoli, M ; Kharrat, R ; Masihi, M ; Ghazanfari, M. H ; Fadaei, S ; Sharif University of Technology
    2012
    Abstract
    Thermodynamic modeling is known as a promising tool for phase behavior modeling of asphaltene precipitation under different conditions such as pressure depletion and CO2 injection. In this work, a thermodynamic approach is used for modeling the phase behavior of asphaltene precipitation. The precipitated asphaltene phase is represented by an improved solid model, while the oil and gas phases are modeled with an equation of state. The PR-EOS was used to perform flash calculations. Then, the onset point and the amount of precipitated asphaltene were predicted. A computer code based on an improved solid model has been developed and used for predicting asphaltene precipitation data for one of... 

    Investigation of thermal effects on machining chatter using FEM simulation of chip formation

    , Article Procedia CIRP ; Volume 1, Issue 1 , 2012 , Pages 50-55 ; 22128271 (ISSN) Hajmohammadi, M. S ; Movahhedy, M. R ; Sharif University of Technology
    2012
    Abstract
    Chatter vibration is a major cause of limitations in increasing material removal rate in machining. Machining chatter is caused by the interaction between tool and work-piece. Various nonlinear phenomena in the machining process affect the occurrence of chatter. Finite element simulation of chip formation allows for incorporation of various factors in the chip formation process. It can therefore be used to simulate the occurrence of chatter in practical conditions and to predict the conditions that lead to stable cutting. In this paper, a one degree of freedom dynamic model of the cutting tool is used to simulate the interaction of machining dynamics with the thermo-mechanical chip formation... 

    The effect of operating temperature on gasochromic properties of amorphous and polycrystalline pulsed laser deposited WO 3 films

    , Article Sensors and Actuators, B: Chemical ; Volume 169 , July , 2012 , Pages 284-290 ; 09254005 (ISSN) Garavand, N. T ; Mahdavi, S. M ; Zad, A. I ; Ranjbar, M ; Sharif University of Technology
    2012
    Abstract
    In this study, tungsten oxide films were synthesized by pulsed laser deposition (PLD) method. The as-deposited films were annealed at a temperature of 250 and 350°C in air for 1 h. The surface morphology, microstructure, crystalline phase and chemical composition of the as-prepared and annealed films were characterized by SEM, XRD and XPS techniques, respectively. Deposition of Pd nanoparticles onto the tungsten oxide surface was performed by hydrogen reduction of a drop-drying PdCl 2 solution onto a WO 3 surface at 60°C. The influence of the annealing temperature on microstructure and gasochromic performance as well as the effect of operating temperature is presented in this work. Results... 

    Thermal interaction of laser beam with particulate flow in mini-channels

    , Article ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2011, 19 June 2011 through 22 June 2011 ; Volume 2 , June , 2011 , Pages 355-366 ; 9780791844649 (ISBN) Zabetian, M ; Saidi, M. S ; Saidi, M. H ; Shafii, M. B ; Sharif University of Technology
    2011
    Abstract
    Optical propulsion via laser source is a relatively new and non-contact tool for manipulation of microscopic objects. The method is based on the radiation pressure of light photons on the micron sized particles. Applications of the technique mainly cover microscopic separation, purification and cellular studies. Due to high power intensity of laser beams, absorption of light may result in heating and damage of objects to be manipulated. In addition, the difference between heated and cold zones can lead to a naturally driven flow around the objects. So precisely controlled conditions should be set up to avoid thermal effects. In this work, a theoretical study is conducted to investigate the... 

    Study of cut-off radius and temperature effects on water molecular behavior using molecular dynamics method

    , Article ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2011, 19 June 2011 through 22 June 2011, Edmonton, AB ; Volume 2 , 2011 , Pages 277-282 ; 9780791844649 (ISBN) Darbandi, M ; Khaledi-Alidusti, R ; Abbaspour, M ; Abbasi, H. R ; Schneider, G ; Sharif University of Technology
    2011
    Abstract
    Water molecules are one of the important molecules in nanofluidics. Its structure and its behavior can change with Temperature and cut-off distance parameters. In this study temperature and cut-off distance effects on the nano-scale water molecules behavior are investigated by molecular dynamics simulations. Many water molecular models have been developed in order to help discover the structure of water molecules. In this study, the flexible three centered (TIP3P-C) water potential is used to model the inter- and intramolecular interactions of the water molecules. In this simulation, we have been studied 512 water molecules with periodic boundary conditions and in a simulation box with 25... 

    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... 

    Low temperature nanostructured zinc titanate by an aqueous particulate sol-gel route: Optimisation of heat treatment condition based on Zn:Ti molar ratio

    , Article Journal of the European Ceramic Society ; Volume 30, Issue 4 , 2010 , Pages 947-961 ; 09552219 (ISSN) Mohammadi, M. R ; Fray, D. J ; Sharif University of Technology
    2010
    Abstract
    Nanocrystalline zinc titanate (ZnTiO3) thin films and powders with purity of 94% were produced at the low sintering temperature of 500 °C and the short sintering time of 1 h by a straightforward aqueous particulate sol-gel route. The effect of Zn:Ti molar ratio was studied on the crystallisation behaviour of zinc titanates. The prepared sols showed a narrow particle size distribution in the range 17-19 nm. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) revealed that the powders contained mixtures of the rhombohedral-ZnTiO3, cubic-ZnO, cubic-Zn2TiO4 phases, as well as the anatase-TiO2 and the rutile-TiO2 depending on the sintering temperature and Zn:Ti molar ratio.... 

    The effect of heat treatment on formation of graphene thin films from graphene oxide nanosheets

    , Article Carbon ; Volume 48, Issue 2 , February , 2010 , Pages 509-519 ; 00086223 (ISSN) Akhavan, O ; Sharif University of Technology
    2010
    Abstract
    Graphene thin films with very low concentration of oxygen-containing functional groups were produced by reduction of graphene oxide nanosheets (prepared by using a chemical exfoliation) in a reducing environment and using two different heat treatment procedures (called one and two-step heat treatment procedures). The effects of heat treatment procedure and temperature on thickness variation of graphene platelets and also on reduction of the oxygen-containing functional groups of the graphene oxide nanosheets were studied by atomic force microscopy and X-ray photoelectron spectroscopy. While formation of the thin films composed of single-layer graphene nanosheets with minimum thickness of... 

    Supersonic flutter prediction of functionally graded conical shells

    , Article Composite Structures ; Volume 92, Issue 2 , 2010 , Pages 377-386 ; 02638223 (ISSN) Mahmoudkhani, S ; Haddadpour, H ; Navazi, H.M ; Sharif University of Technology
    2010
    Abstract
    Aero-thermoelastic analysis of a simply supported functionally graded truncated conical shell subjected to supersonic air flow is performed to predict the flutter boundaries. The temperature-dependent properties of the FG shell are assumed to be graded through the thickness according to a simple rule of mixture and power-law function of volume fractions of material constituents. Through the thickness steady-state heat conduction is considered for thermal analysis. To perform the stability analysis, the general nonlinear equations of motion are first derived using the classical Love's shell theory and the von Karman-Donnell-type of kinematic nonlinearity together with the linearized... 

    Physically based material model for evolution of stress-strain behavior of heat treatable aluminum alloys during solution heat treatment

    , Article Materials and Design ; Volume 31, Issue 1 , 2010 , Pages 433-437 ; 02641275 (ISSN) Anjabin, N ; Karimi Taheri, A ; Sharif University of Technology
    2010
    Abstract
    A mathematical model based on Kocks-Mecking-Bergstrom model, has been proposed to predict the flow behavior of age hardenable aluminum alloys, under different conditions of solution heat treatment and hot deformation. Considering the published literature, most researchers have taken into account the precipitation and solution strengthening contribution to the flow stress by a constant and some others have ignored these effects. So these available descriptions cannot be applicable directly to different conditions of solution heat treatment. In order to enable these constitutive descriptions to take into account the effects of soaking time and temperature, we introduce in this research a... 

    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  

    Hot filament CVD of Fe-Cr catalyst for thermal CVD carbon nanotube growth from liquid petroleum gas

    , Article Applied Surface Science ; Volume 256, Issue 5 , 2009 , Pages 1365-1371 ; 01694332 (ISSN) Akbarzadeh Pasha, M ; Shafiekhani, A ; Vesaghi, M. A ; Sharif University of Technology
    Abstract
    A hot filament chemical vapor deposition (HFCVD) method was used to prepare Fe-Cr thin film on Si substrate. The produced layers were used as catalysts for growing carbon nanotubes (CNTs) from liquid petroleum gas (LPG) at 825 °C by thermal CVD (TCVD) method. To characterize the obtained catalysts or CNTs, X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Raman spectroscopy were used. CNTs were grown on HFCVD derived Fe-Cr catalyst with the LPG as carbon source successfully. It was found that an annealing process on catalysts enhances the surface concentration of Cr atoms and reduces the sizes of catalyst particles. The...