Search for: thermal-behaviors
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    Partially aromatic polyamides based on tetraphenylthiophene diamine: Synthesis and characterization [electronic resource]

    , Article Journal of Applied Polymer Science ; Volume 77, Issue 5, pages 1144–1153, 1 August 2000 Pourdjavadi, A. (Ali) ; Zamanlu, M. R ; Zohuriaan-Mehr, M. J ; Sharif University of Technology
    Tetraphenylthiophene diamine (TPTDA) was prepared through a modified three-step route to achieve an improved overall yield. TPTDA reacted with succinic, adipic, suberic, sebasic, and fumaric acids via the Yamazaki phosphorylation method to yield novel partially aromatic polyamides (TPT series). A counterpart polyamide series based on p-phenylene diamine (Ph series) was also synthesized under the same conditions. All of the polymers were characterized by means of spectrochemical (Fourier transform infrared spectroscopy, 1H-nuclear magnetic resonance (NMR), and 13C-NMR) and thermal (differential scanning calorimetry and thermogravimetric) methods of analysis. Solubility of TPT polyamides was... 

    Transient thermal behavior of radial fins of rectangular, triangular and hyperbolic profiles with temperature-dependent properties using DTM-FDM

    , Article Journal of Central South University ; Volume 24, Issue 3 , 2017 , Pages 675-682 ; 20952899 (ISSN) Mosayebidorcheh, S ; Rahimi Gorji, M ; Ganji, D. D ; Moayebidorcheh, T ; Pourmehran, O ; Biglarian, M ; Sharif University of Technology
    Central South University of Technology  2017
    This work focuses on transient thermal behavior of radial fins of rectangular, triangular and hyperbolic profiles with temperature-dependent properties. A hybrid numerical algorithm which combines differential transformation (DTM) and finite difference (FDM) methods is utilized to theoretically study the present problem. DTM and FDM are applied to the time and space domains of the problem, respectively. The accuracy of this method solution is checked against the numerical solution. Then, the effects of some applicable parameters were studied comparatively. Since a broad range of governing parameters are investigated, the results could be useful in a number of industrial and engineering... 

    Study of thermal behavior of CrO3 using TG and DSC

    , Article Journal of Thermal Analysis and Calorimetry ; Vol. 116, Issue. 2 , 2014 , pp. 915-921 ; ISSN: 13886150 Sajadi, S. A. A ; Khaleghian, M ; Sharif University of Technology
    Using two techniques of thermogravimetry and differential scanning calorimetry under O2 and N2 gas atmosphere from 25 to 600 °C, the thermal behavior of chromium(VI) oxide CrO3 was investigated. The identity of products at different decomposition steps was confirmed by XRD technique. Both techniques produced similar results supporting the same steps for the compound. The received products were investigated by SEM electron microscope. The form and the size of crystals were investigated. Three distinct energy changes were observed, namely, two endothermic and one exothermic in DSC. The amount of ΔH for each peak is also reported  

    Adhesion and Viscoelestisity of EVA Hot Melt Adhesive

    , M.Sc. Thesis Sharif University of Technology Bank, Mohammad Mahdi (Author) ; Frounchi, Masuod (Supervisor) ; Dadbin, Susan (Supervisor)
    A series of poly(ethylene-co-vinyl acetate) (EVA)-based hot melt adhesives containing either a raw rosin or a hydrogenated rosin ester have been prepared to investigate variation of viscosity, softening point and peel adhesion with composition. Adhesion of the prepared hot melt adhesive to the substrate was characterized by T-peel strength test. Increasing rosin had a prominent effect on the adhesion. Viscosity decreased and softening point increased as the wax content increased. Addition of zinc borate as a flame retardant decreased T-peel energy and increased the viscosity and softening point of the samples. Higher peeling strength accompanied with a good softening point and viscosity... 

    Thermal Behavior of Rechargeable Li-ion Batteries; Experimental Evaluations and Modeling

    , Ph.D. Dissertation Sharif University of Technology Shadman Rad, Mojtaba (Author) ; Baghalha, Morteza (Supervisor) ; Kazemeini, Mohammad (Co-Advisor)
    The main objective of this research is to experimentally evaluate thermal behavior of commercially available rechargeable Li-ion batteries based on minimum measurements on main battery parameters and then develop experimental based models to investigate their thermal behavior. Li-ion batteries with Graphit anodes and Li(Ni0.8¬Co0.15Al0.05)O2 cathodes will be used for this purpose. Voltage and temperature developments during cycling under various currents at controlled ambient temperatures are measured by battery tester. Measurements show that temperature evolutions demonstrate falls and rises at specific State-of-Charge (SoC) of the battery during cycling and therefore some heat consumers... 

    Investigation of thermal behavior of α-PbO and β-PbO IN O2 atmosphere

    , Article Metalurgija ; Volume 57, Issue 4 , 2018 , Pages 287-290 ; 05435846 (ISSN) Sajadi, S. A. A ; Nazari Alavi, A ; Mirzai, M ; Sharif University of Technology
    Faculty of Metallurgy  2018
    The compounds α-lead oxide (α-PbO) and β-lead oxide (β-PbO) were purchased from Merck co. and used for thermal investigations in laboratory. The compound was heated in a thermogravimeter at different temperature, from 25 to 400 °C. The used gas atmosphere was O2. The received products were investigated by X-ray diffraction (XRD) technique. The received product Pb3O4 was confirmed by XRD. The textures of two different morphologies of α-PbO, β-PbO and the product Pb3O4 is investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. © 2018, Faculty of Metallurgy. All rights reserved  

    Quartic balance theory: Global minimum with imbalanced triangles

    , Article Physical Review E ; Volume 102, Issue 1 , 2020 Kargaran, A ; Ebrahimi, M ; Riazi, M ; Hosseiny, A ; Jafari, G. R ; Sharif University of Technology
    American Physical Society  2020
    Balance theory proposed by Heider for the first time modeled triplet interaction in a signed network, stating that relationships between two people, friendship or enmity, is dependent on a third person. The Hamiltonian of this model has an implicit assumption that all triads are independent, meaning that the type of each triad, being balanced or imbalanced, determined apart from the state of other triads. This independence forces the network to have completely balanced final states. However, there exists evidence indicating that real networks are partially balanced, raising the question of what is the mechanism preventing the system to be perfectly balanced. Our suggestion is to consider a... 

    Modal control of thermoplasmonic behavior of nanostructures based on excitation of perfect absorption resonances

    , Article Journal of the Optical Society of America B: Optical Physics ; Volume 37, Issue 8 , 2020 , Pages 2238-2247 Yazdanfar, P ; Heydarian, H ; Rashidian, B ; Sharif University of Technology
    OSA - The Optical Society  2020
    Controlling the localized heat generation density and temperature profile of nanostructures exploiting perfect absorption of individual resonance modes is reported. The methodology is applied to spherically symmetric nanostructures using the T-matrix method. It is demonstrated that perfect modal splitting of the absorption power at desired wavelengths and individual excitation of the modes provide the ability to localize the generated heat at desired locations, and control the resulting temperature profile in multilayer core–shell structures. By knowing the thermal behavior of individual modes, it is shown that excitation of the perfect absorption modes at desired temperatures can result in... 

    Thermal behavior of alkaline lead acetate, a study of thermogravimetry and differential scanning calorimetry

    , Article Scientia Iranica ; Volume 15, Issue 4 , 2008 , Pages 435-439 ; 10263098 (ISSN) Sajadi, S. A. A ; Alamolhoda, A. A ; Hashemian, S. J ; Sharif University of Technology
    Sharif University of Technology  2008
    The compound, alkaline lead acetate, Pb(CH3COO)2·PbO·H2O (ALA), was purchased from the Fluka Company. The X-ray diffraction film and SEM electron microgaph of this compound were obtained and reported in this paper for the first time. The thermal behavior of alkaline lead acetate (ALA) was studied using thermogravimetery (TGA) and Differential Scanning Calorimetery (DSC) techniques under an O2 gas atmosphere from 25 to 600°C. Four distinct energy changes associated with weight changes were observed, all of them being exothermic in the DSC results. The amount of ΔH for each peak is reported. © Sharif University of Technology  

    Formation of Lanthanum hydroxide nanostructures: effect of NaOH and KOH solvents

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 21, Issue 2 , 2008 , Pages 169-176 ; 1728-144X (ISSN) Mazloumi, M ; Zanganeh, S ; Kajbafvala, A ; Shayegh, M. R ; Sadrnezhaad, S. K ; Sharif University of Technology
    Materials and Energy Research Center  2008
    Lanthanum hydroxide (La(OH)3) nanostructures, including elliptical nanoparticles, octahedral rods and irregular nanoparticles were prepared chemically in NaOH and KOH solutions with 10 M concentration. The obtained powders were characterized with XRD, SEM, TEM and DTA. Crystallinities, morphologies and thermal behavior of the obtained nanostructure powders were investigated under the influence of above mentioned solvents. The effect of chemical's temperature was also determined in one of the solvents (i.e. NaOH). The formation of growth in nanostructure mechanism under the influence of alkali solutions (i.e., KOH and NaOH) have been discussed considerably in this paper  

    Mathematical modeling of the reaction in an iron ore pellet using a mixture of hydrogen, water vapor, carbon monoxide and carbon dioxide: An isothermal study

    , Article Advanced Powder Technology ; Volume 17, Issue 3 , 2006 , Pages 277-295 ; 09218831 (ISSN) Valipour, M. S ; Motamed Hashemi, M. Y ; Saboohi, Y ; Sharif University of Technology
    VSP BV  2006
    A mathematical time-dependent and isothermal model based on the grain model has been developed to simulate the kinetic and thermal behaviors of a porous iron oxide pellet undergoing chemical reactions with a mixture of hydrogen, carbon monoxide, carbon dioxide and water vapor. Its novelty consists in fact that it can deal with a multi-species reducing gas and oxide pellet. In spite of previous models in which the pure reductant was applied as reducing gas, this model can indicate an actual view of pellet reduction including the effects of reducing gas utility and reducing gas ratio. A finite volume fully implicit technique was applied for solving the governing equations. The model has been... 

    Formulation and Investigation of Thermal Behavior and Flexural Properties of PMMA Denture base Reinforced with Modified Nanoparticles m-HAP and m-MWCNTs

    , M.Sc. Thesis Sharif University of Technology Shahkar, Lachin (Author) ; Nemati, Ali (Supervisor) ; Malek Khachatourian, Adrineh (Supervisor)
    This study investigates the effect of adding hydroxyapatite nanoparticles and multi-walled carbon nanotubes in pure and modified form on the flexural properties and hardness of denture base Polymethyl Methacrylate. Polymethyl Methacrylate (PMMA) is still the most common denture base material. In fact, the mechanical properties of this resin have played a significant role in expanding its use in dentistry. But in the long-term use of resins, defects such as low resistance to crack growth, low flexural strength and brittleness can be seen. In fact, flexural fatigue occurs as a result of repeated flexural stresses, and it can be described as the main reason for crack growth and propagation in... 

    Prediction of thermal responses in continuous hot strip rolling processes

    , Article Production Engineering ; Vol. 9, issue. 1 , Jul , 2014 , p. 79-86 Sayadi, H ; Serajzadeh, S ; Sharif University of Technology
    Thermal behavior and require power in hot continuous strip rolling are predicted by means of a coupled finite element-upper bound approach. A thermal-finite element analysis is utilized to simultaneously determine temperature distributions within the work-piece and the work-rolls while an upper bound solution is employed at the same time to estimate the rate of heat of deformation and the required power in each rolling stand. The proposed model can be applied for determining thermal behaviors of the strip and the work-rolls in single and multi- pass rolling schedules while the effects of different parameters including initial temperature and rolling speed can be considered in the analysis.... 

    Thermal performance of a kerosene-fired variable-mixing oxy-fuel burner

    , Article 48th AIAA Fluid Dynamics Conference, 2018, 25 June 2018 through 29 June 2018 ; 2018 ; 9781624105531 (ISBN) Darbandi, M ; Ghafourizadeh, M ; Schneider, G. E ; Sharif University of Technology
    American Institute of Aeronautics and Astronautics Inc, AIAA  2018
    In this study, we simulate the thermal behavior of a kerosene-fired oxy-fuel burner. To do this, the velocity of pure oxygen is suitably changed to achieve variable-mixing of fuel and oxidizer. Before the simulation procedure, a number of primitive steps are taken to evaluate the selected numerical approaches and methods. In other words, we simulate the turbulent non-premixed kerosene–air flame confined in a combustor and compare the achieved numerical solutions with the available measurements to appraise the validity of achieved solutions. The comparisons are mainly provided for the predicted flame structure. The comparison indicates that the achieved numerical solutions are accurate enough... 

    Room temperature synthesis of highly crystalline TiO2 nanoparticles

    , Article Materials Letters ; Volume 92 , February , 2013 , Pages 287-290 ; 0167577X (ISSN) Sasani Ghamsari, M ; Radiman, S ; Azmi Abdul Hamid, M ; Mahshid, S ; Rahmani, S ; Sharif University of Technology
    Hydrolysis of titanium isopropoxide alcoholic solution has been used to prepare the crystallized TiO2 nanoparticles at low temperature. Concentration ratio was used to control the pathway of sol-gel process and change the physical characteristics of TiO2 nanopowders. The crystallinity, morphology and size of aged TiO2 nanopowders were studied by X-ray diffraction and Scanning Electron Microscopy (SEM). FTIR and, Thermo-Gravimetric (TG) analysis were used to identify the functional groups and thermal behavior of prepared samples. Experimental results have shown that high crystalline TiO2 nanomaterial with anatase polymorph can be obtained at room temperature. It has been found that the... 

    Heat transfer characteristics of mixed electroosmotic and pressure driven flow of power-law fluids in a slit microchannel

    , Article International Journal of Thermal Sciences ; Volume 53 , 2012 , Pages 71-79 ; 12900729 (ISSN) Babaie, A ; Saidi, M. H ; Sadeghi, A ; Sharif University of Technology
    Thermal transport characteristics of electroosmotic flow of power-law fluids in the presence of pressure gradient through a slit microchannel are studied in this paper. Considering a fully developed flow with a constant wall heat flux as the boundary condition, the governing equations are numerically solved by means of the finite difference method. A complete parametric study is done in order to investigate the effects of different flow parameters on the thermal behaviors of the flow. The results show that the non-Newtonian characteristic of the fluid can influence the thermal behaviors of the flow by affecting the rate of heat convection and viscous dissipation; however, its influence... 

    Innovative semi-analytical methodology to predict automobile body temperature distribution in the curing ovens

    , Article Heat Transfer Engineering ; Volume 33, Issue 2 , Jun , 2012 , Pages 109-117 ; 01457632 (ISSN) Hanafizadeh, P ; Sajadi, B ; Saidi, M. H ; Sharif University of Technology
    In automobile painting industries, new automobile body products frequently should be tested in order to determine the actual thermal behavior of a paint curing process before starting mass production. During the hardening processes of dipped paint coating, applied in the electrophoretic enameling process, or top paint coating, applied in the final coating process, the automobile body must be warmed up according to the specific paint manufacturer curve. Consequently, prediction of car body temperature during the curing process may be vital in the design and performance analysis of the paint ovens. Numerical simulation of these processes may reduce expensive and time-consuming experimental... 

    Comparative investigation of low and high frequency pulse tube regenerators

    , Article Scientia Iranica ; Volume 18, Issue 2 B , April , 2011 , Pages 205-212 ; 10263098 (ISSN) Jafarian, A ; Roshanghalb, F ; Saidi, M. H ; Imanimehr, F ; Sharif University of Technology
    The objective of the present work is to compare the performance of the regenerator of pulse tube refrigerators at low and high frequencies. The hydrodynamic and thermal behavior of the regenerator is investigated in this respect. To consider the system performance, a system of conservation equations including two energy equations for the regenerator as a porous media is employed. The present model considers one-dimensional, periodic, unsteady, compressible flow in the regenerator. The conservation equations are transformed by implementing the volumetric average scheme. The method of harmonic approximation is employed to derive an analytical solution. To explore the system performance, net... 

    First and second law analysis of fluid flow in the regenerator of pulse tube refrigerators

    , Article 2010 14th International Heat Transfer Conference, IHTC 14, 8 August 2010 through 13 August 2010, Washington, DC ; Volume 4 , 2010 , Pages 247-255 ; 9780791849392 (ISBN) Roshanghalb, F ; Saidi, M. H ; Jafarian, A ; Imanimehr, F ; Asadi, M ; Sharif University of Technology
    The objective of the present work is to analyze the performance of the regenerator of pulse tube refrigerators. Hydrodynamic and thermal behavior of the regenerator is investigated in this respect. To consider the system performance, a system of conservation equations including two energy equations for the regenerator as a porous media is employed. The present model considers one dimensional periodic unsteady compressible flow in the regenerator. The conservation equations are transformed by implementing the volumetric average scheme. Method of harmonic approximation is employed to derive an analytical solution. To explore the system performance, net energy flow and entropy generation... 

    Synthesis and characterization of bagasse poly(methyl methacrylate) graft copolymer

    , Article Macromolecular Symposia ; Volume 274, Issue 1 , 2008 , Pages 49-54 ; 10221360 (ISSN) Sarvi, I ; Pourjavadi, A ; Noei Aghaei, M. A ; Sharif University of Technology
    Graft copolymerization of methyl methacrylate (MMA) was carried out on bagasse fibers in an aqueous medium using eerie ammonium nitrate (CAN) as initiator under a neutral atmosphere. In order to obtain the optimum condition for graft copolymerization, the effects of initiator concentration, temperature, time of reaction, and monomer concentration were studied. The maximum grafting percent was found to be 122%. The bagasse grafted poly(methyl methacrylate) was characterized by FTIR and its thermal behavior was characterized by TGA. Copyright © 2008 WILEY-VCH Verlag GmbH & Co. KGaA