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mahboubi--d
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Optimal behavior of hot water heating coils at steady conditions
, Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 10, Issue PART B , 2009 , Pages 1427-1432 ; 9780791848715 (ISBN) ; Saldi, M. H ; Sharif University of Technology
2009
Abstract
Hot water heating coils are key components in air conditioning systems undergo heat transfer. The most widely used exchangers (coils) take the form of fin and tube configuration in association with the application of air conditioning systems. In this research, thermodynamic modeling and mathematical optimization of hot water heating coils at steady conditions, approaching minimum energy consumption are achieved. The modeling procedure for heating coils is done based on the log mean temperature difference (LMTD) method. The objective function for optimization is pressure drop of air crossing coil per heating load of the system. This unction comprises all thermal and geometrical parameters of...
Multi-objective Optimization of a Megawatt Wind Turbine Blade Geometry Using an Evolutionary Algorithm
, M.Sc. Thesis Sharif University of Technology ; Darbandi, Masoud (Supervisor)
Abstract
Without optimization, it is impossible to reduce the cost of power generation from an efficient megawatt wind turbine. In this work, we present a multi-objective algorithm to optimize the megawatt blade geometry. In this algorithm, the mass of blade and the wind turbine annual energy production (AEP) are considered as the objective functions. The design variables are blade chord, blade twist, airfoil thickness, spar geometry and blade curvature distribution.The constraints are maximum allowable strain for the chosen materials, maximum tip deflection and maximum tip speed. For the internal geometry, we consider two spars and four panels. The blade element momentum method (BEM) is used for...
Developing an electro-thermal model to determine heat generation and thermal properties in a lithium-ion battery
, Article Journal of Thermal Analysis and Calorimetry ; Volume 147, Issue 21 , 2022 , Pages 12253-12267 ; 13886150 (ISSN) ; Jafari Gavzan, I ; Saidi, M. H ; Ahmadi, N ; Sharif University of Technology
Springer Science and Business Media B.V
2022
Abstract
Lithium-ion batteries should continuously be operated at the optimum temperature range (15∼40∘C) for the best performance. Surface temperature monitoring is critical for the safe and efficient operation of the battery. In this study, initially, the electrical parameters of the battery are determined by applying a second-order equivalent circuit model. This model then is integrated with a thermal model based on the temperature dependent behavior of the electrical parameters and the heat generated. The input parameters to the electro-thermal model include the current, the ambient fluid temperature and the output parameters include the terminal voltage, state of charge, cell core temperature...
State of charge estimation for lithium-ion batteries based on square root sigma point Kalman filter considering temperature variations
, Article IET Electrical Systems in Transportation ; Volume 12, Issue 3 , 2022 , Pages 165-180 ; 20429738 (ISSN) ; Jafari Gavzan, I ; Saidi, M. H ; Ahmadi, N ; Sharif University of Technology
John Wiley and Sons Inc
2022
Abstract
The battery management system (BMS) in electric vehicles monitors the state of charge (SOC) and state of health (SOH) of lithium-ion battery by controlling transient parameters such as voltage, current, and temperature prevents the battery from operating outside the optimal operating range. The main feature of the battery management system is the correct estimation of the SOC in the broad range of vehicle navigation. In this paper, to estimate real-time of SOC in lithium-ion batteries and overcome faults of Extended Kalman Filter (EKF), the Square-Root Sigma Point Kalman Filter is applied on the basis of numerical approximations rather than analytical methods of EKF. For this purpose, the...
Synthesis and Characterization of Grapheme Foams Fabricated by Chemical Vaporization Deposition
, M.Sc. Thesis Sharif University of Technology ; Akhavan, Omid (Supervisor) ; Azimirad, Rouhollah (Co-Advisor)
Abstract
The main purpose of this theses is to synthesize graphene by chemical vapor deposition (CVD) of a hydrocarbon gas such as methane on the nickel foam substrate and then to characterize this kind of graphene. Graphene is a single layer of carbon atoms, discovered in 2004, which has led mankind to new eras in all fields by its extraordinary features such as extra high electron mobility, high thermal conductivity, excellent mechanical strength, optical transparence and extra high specific surface. The advantage of this method compared to other methods is that the graphene generated has a better structural quality. Graphene foam firstly, because of the continuity of the foam structure, has better...
Preparation and characterization of PVA/chitosan nanofibers loaded with Dragon's blood or poly helixan as wound dressings
, Article International Journal of Biological Macromolecules ; Volume 272 , 2024 ; 01418130 (ISSN) ; Mehrabi, M ; Aghaie, F ; Bitaraf, F. S ; Dehghani, F ; Bernkop Schnürch, A ; Sharif University of Technology
2024
Abstract
Nanofibers have been investigated in regenerative medicine. Dragon's blood (DB)- and poly helixan PF (PHPF) are natural materials used in cosmetics. Herein, we generated DB- and PHPF-loaded polyvinyl alcohol/chitosan (PVA/CS/DB and PVA/CS/PHPF, respectively) nanofibers. PVA/CS/DB and PVA/CS/PHPF nanofibers had an average diameter of 547.5 ± 17.13 and 521 ± 24.67 nm, respectively as assessed by SEM, and a degradation rate of 43.1 and 47.6 % after 14 days, respectively. PVA/CS/DB and PVA/CS/PHPF nanofibers had a hemolysis rate of 0.10 and 0.39 %, respectively, and a water vapor transmission rate of ∼2200 g.m−2.day−1. These nanofibers exhibited favorable antimicrobial activity against...
Intralesional immunotherapy compared to cryotherapy in the treatment of warts
, Article International Journal of Dermatology ; Volume 56, Issue 4 , 2017 , Pages 474-478 ; 00119059 (ISSN) ; Jabbari Azad, F ; Mahboubi Oskouei, Y ; Jafari, M ; Tehranian, S ; Alizadehsani, R ; Layegh, P ; Sharif University of Technology
Blackwell Publishing Ltd
2017
Abstract
Background: Warts are the most common clinical manifestation of the human papilloma-virus infection in the skin and mucous membranes. In spite of the various therapeutic modalities for nongenital skin warts, there is still no single method to be used as an approved treatment. In this study, we compared the efficacy of immunotherapy and cryotherapy on wart lesions. Methods: Sixty patients with verruca vulgaris and plantar warts were randomly divided into two groups. One group received intralesional injection of candida antigen repeated every 3 weeks until complete improvement of all warts or for a maximum of three sessions. The second group was treated by cryotherapy with liquid nitrogen for...
Data science and predictive analytics : biomedical and health applications using R
, Book
Springer International Publishing AG
2018
Synergistic effect of MEHPA on co-extraction of zinc and cadmium with DEHPA
, Article Minerals Engineering ; Volume 17, Issue 1 , 2004 , Pages 89-92 ; 08926875 (ISSN) ; Moradkhani, D ; Darvishi, D ; Askari, M ; Behnian, D ; Sharif University of Technology
2004
Abstract
Simultaneous extraction of zinc and cadmium by a mixture of di-2-ethyl hexyl phosphoric acid (DEHPA) and mono-2-ethyl hexyl phosphoric acid (MEHPA), and the synergistic effect of MEHPA on co-extraction of zinc and cadmium with DEHPA have been investigated. It was shown that the extraction of zinc and cadmium by DEHPA and/or MEHPA can be increased by an increase of pH. The results also illustrate that the pH0.5 of zinc, by increase in MEHPA from 0.1 to 8 vol%, did not vary significantly while that of cadmium varies from 0.63 to 2.4. In other words MEHPA prevents selective extraction of zinc from aqueous media containing both zinc and cadmium. Studies on the selective separation parameter...
Investigating the convective flow of ternary hybrid nanofluids and single nanofluids around a stretched cylinder: Parameter analysis and performance enhancement
, Article International Journal of Thermofluids ; Volume 23 , 2024 ; 26662027 (ISSN) ; Hosseinzadeh, K ; Ganji, D. D ; Sharif University of Technology
2024
Abstract
Within this research, we examined the convective flow of a blend of ternary hybrid nanofluids and single nanofluids with a stagnation point caused by a stretched cylinder. The purpose of this study is to investigate the effect of using a ternary hybrid nanofluid instead of a single nanofluid. Water is used as the base fluid in this investigation. The single nanofluid is made of copper and the ternary hybrid nanofluid is made of Molybdenum disulfide, copper, and silver. The impact of the curvature parameter, nanoparticle volume fraction, mixed convection parameter, velocity ratio, shape factor, conjugate number and Eckert number parameters on temperature and velocity profiles has been...
MHD flow in a channel using new combination of order of magnitude technique and HPM [MHD tok u kanalu uporabom novih kombinacija tehnika grubog opisa vrijednosti i HPM]
, Article Tehnicki Vjesnik ; Volume 21, Issue 2 , April , 2014 , Pages 317-321 ; ISSN: 13303651 ; Ganji, D. D ; Rahni, M. T ; Sharif University of Technology
2014
Abstract
The present work is concerned with the steady incompressible flow through a parallel plate channel with stretching walls under an externally applied magnetic field. The governing continuity and Navier-Stokes equations are reduced to a fourth order nonlinear differential equation by using vorticity definition and similarity solution transformation. The obtained equations are solved by applying the analytical homotopy perturbation method (HPM). The method is called order of magnitude suggested for simplifying series solution to finite expression that is useful in engineering problems. The results are verified by comparing with numerical solutions and demonstrate a good accuracy of the obtained...
Analytical solution of nonlinear differential equations two oscillators mechanism using Akbari-Ganji method
, Article Modern Physics Letters B ; Volume 35, Issue 31 , 2021 ; 02179849 (ISSN) ; Hosseinzadeh, K ; Rahai, M ; Ganji, D. D ; Sharif University of Technology
World Scientific
2021
Abstract
In the last decade, many potent analytical methods have been utilized to find the approximate solution of nonlinear differential equations. Some of these methods are energy balance method (EBM), homotopy perturbation method (HPM), variational iteration method (VIM), amplitude frequency formulation (AFF), and max-min approach (MMA). Besides the methods mentioned above, the Akbari-Ganji method (AGM) is a highly efficient analytical method to solve a wide range of nonlinear equations, including heat transfer, mass transfer, and vibration problems. In this study, it was constructed the approximate analytic solution for movement of two mechanical oscillators by employing the AGM. In the derived...
A compiler for multi-key homomorphic signatures for Turing machines
, Article Theoretical Computer Science ; Volume 889 , 2021 , Pages 145-170 ; 03043975 (ISSN) ; Fiore, D ; Venturi, D ; Amini, M ; Sharif University of Technology
Elsevier B.V
2021
Abstract
At SCN 2018, Fiore and Pagnin proposed a generic compiler (called “Matrioska”) allowing to transform sufficiently expressive single-key homomorphic signatures (SKHSs) into multi-key homomorphic signatures (MKHSs) under falsifiable assumptions in the standard model. Matrioska is designed for homomorphic signatures that support programs represented as circuits. The MKHS schemes obtained through Matrioska support the evaluation and verification of arbitrary circuits over data signed from multiple users, but they require the underlying SKHS scheme to work with circuits whose size is exponential in the number of users, and thus can only support a constant number of users. In this work, we propose...
Ride comfort of high-speed trains travelling over railway bridges
, Article Vehicle System Dynamics ; Volume 43, Issue 3 , 2005 , Pages 173-197 ; 00423114 (ISSN) ; Younesian, D ; Thompson, D ; Jones, C ; Sharif University of Technology
Taylor and Francis Ltd
2005
Abstract
The ride comfort of high-speed trains passing over railway bridges is studied in this paper. A parametric study is carried out using a time domain model. The effects of some design parameters are investigated such as damping and stiffness of the suspension system and also ballast stiffness. The influence of the track irregularity and train speed on two comfort indicators, namely Sperling's comfort index and the maximum acceleration level are also studied. Two types of railway bridges, a simple girder and an elastically supported bridge are considered. Timoshenko beam theory is used for modelling the rail and bridge and two layers of parallel damped springs in conjunction with a layer of mass...
Entropy generation analysis of kerosene oil flow with ternary hybrid nanoparticles on the stretchable exponential surface
, Article International Journal of Modelling and Simulation ; 2024 ; 02286203 (ISSN) ; Hosseinzadeh, K ; Najafpour, A ; Ganji, D. D ; Sharif University of Technology
2024
Abstract
In this research, the flow of kerosene oil with ternary hybrid nanoparticles on a stretchable exponential surface has been investigated. There is also a discussion about the entropy analysis of the flow of hydromagnetic radiation by the surface. The ternary hybrid nanofluid (THyNF) contains graphene oxide (GO), magnesium oxide (MgO), and zinc oxide (ZnO) as nanoparticles and kerosene oil as a base fluid. Using useful transformations, differential equations with partial derivatives (PDEs) were transformed into ordinary differential equations (ODEs). Then, the ODEs were solved using the RK5th method. Furthermore, the impacts of parameters like radiation parameter ((Formula presented.)),...
The investigation of pre-ionization effect on the improvement of pinch quality and increased hard X-ray radiation in a dense plasma focus (DPF) device
, Article Journal of Fusion Energy ; Volume 43, Issue 1 , 2024 ; 01640313 (ISSN) ; Vosoughi, N ; Mahabadi, T. D ; Piriaei, D ; Sharif University of Technology
2024
Abstract
This study delves into the impact of the pre-ionization technique, facilitated by an optimal shunt resistor, on a DPF device operating with deuterium gas. The investigation unveils enhancements in critical parameters within the plasma column environment during the pinch phase, specifically the total and plasmoid hard x-ray yields. Employing a combination of time-resolved detectors, such as plastic scintillator and magnetic probe arrays, alongside time-integrated detectors like pinhole camera, and just by using this technique, the research illustrated an augmented plasma sheath velocity during the axial phase. Notably and other than the enhancement of hard x-ray yield, the optimal pressure of...
Heat transfer hybrid nanofluid (1-Butanol/MoS2–Fe3O4) through a wavy porous cavity and its optimization
, Article International Journal of Numerical Methods for Heat and Fluid Flow ; 2020 ; Montazer, E ; Shafii, M. B ; Ganji, D. D ; Sharif University of Technology
Emerald Group Holdings Ltd
2020
Abstract
Purpose: The purpose of this paper is to investigate natural convection in a porous wavy-walled enclosure that is including a cylinder cavity in the middle of it and filled with a hybrid nanofluid contains 1-Butanol as the base fluid and MoS2–Fe3O4 hybrid nanoparticles. Design/methodology/approach: The domain of interest is bounded by constant temperature horizontal corrugated surfaces and isothermal vertical flat surfaces. The numerical outputs are explained in the type of isotherms, streamline and average Nusselt number with variations of the Rayleigh number, Hartmann number, nanoparticle shape factor and porosity of the porous medium. For solving the governing equations, the finite...
Detection of ammonia gas by knudsen thermal force in micro gas actuator
, Article Case Studies in Thermal Engineering ; Volume 12 , 2018 , Pages 276-284 ; 2214157X (ISSN) ; Barzegar Gerdroodbary, M ; Mosavat, M ; Ganji, D. D ; Sharif University of Technology
2018
Abstract
Direct Simulation Monte Carlo (DSMC) method is applied to evaluate the performance of a new micro gas sensor (MIKRA) for mass analysis of ammonia in the rarefied gas. In order to simulate a rarefied gas inside the micro gas detector, Boltzmann equation is applied to obtain high precision results. This study performed comprehensive studies to reveal the main mechanism of force generation and applied this for the analysis of the gas mixture. Our findings show that value of generated Knudsen force significantly varies when the percentage of the NH3 varies in the mixture. According to obtained results, the maximum Knudsen force increases when the fraction of the ammonia decreases. Our findings...
Dual-phase-lag thermoelastic damping in nonlocal rectangular nanoplates
, Article Waves in Random and Complex Media ; Volume 34, Issue 1 , 2024 , Pages 162-181 ; 17455030 (ISSN) ; Cheng, D ; Cong, G ; Jin, D ; Borjalilou, V ; Sharif University of Technology
2024
Abstract
The present article pertains to the assessment of thermoelastic damping (TED) in rectangular nanoplates by incorporation of size effect within the constitutive and heat conduction relations. With the purpose of establishing size-dependent coupled thermoelastic equations, nonlocal elasticity theory and dual-phase-lag heat conduction model are utilized. By considering time-harmonic vibrations, nonclassical frequency equation affected by thermoelastic coupling is derived. By solving this equation and extracting the real and imaginary parts of damped natural frequency via some mathematical operations, an explicit expression for description of TED in circular nanoplates is obtained. With the goal...
Hydrothermal assessment of a double-pass shell and tube heat exchanger in the presence of blade turbulators with different configurations
, Article International Journal of Thermofluids ; Volume 21 , Volume 21 , 2024 ; 26662027 (ISSN) ; Hosseinzadeh, K ; Ranjbar Kermani, J ; Ganji, D. D ; Sharif University of Technology
Elsevier
2024
Abstract
Heat exchangers (HE) are one of the vital heat transfer equipment that have various applications in disparate industries. In this regard, countless methods have been implemented to increase and optimize the heat transfer process inside them. However, passive techniques have received more attention due to the absence of external power consumption. In this study, the impact of employing turbulators with various geometries on the overall heat transfer coefficient (HTC), flow pressure drop (PD), and temperature distribution in the shell-and-tube heat exchanger (STHE) has been computationally investigated. Moreover, for a better examination, the effect of variation of the middle diameter of the...