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dehghani-firoozabadi--hamed
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Beyond the Standard Model Concentrating on the Supersymmetry
, M.Sc. Thesis Sharif University of Technology ; Golshani, Mehdi (Supervisor)
Abstract
In this thesis, a general survey and reviewis done about the models that go beyond the standard model. Even it contains the great subjects like quantum gravity and alternative Quantum field theories. In addition to them, we concentrate on the supersymmetry that is one of the most important subjects in the beyond the standard model. Recently, the validityof supersymmetry has confronted a lot of controversy. This motivates reconsideration of many supersymmetric models. So we survey the main motivations and problems of the supersymmetry and finally we discuss some possible solutions to the problems
Vibration and Buckling Analysis of Thick FGM Conical Shells Under Variable Thermal and Pressure Distributions, Considering Initial Geometric Imperfections Using a Higher Order TheoryVibration and Buckling Analysis of Thick FGM Conical Shells Under Variable Thermal and Pressure Distributions, Considering Initial Geometric Imperfections Using a Higher Order Theory
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firoozabadi, Rouhollah (Supervisor)
Abstract
The current study is dedicated to free vibration and buckling analysis of thick FGM conical shells conveying hot flows with the consideration of initial geometric imperfections. To this end, the higher order governing equations of motion and the corresponding boundary conditions are derived using Hamiltonian formulations. Due to the solution procedure of Frobenius series expansion, the differential form of equations is obtained by applying by part integration to the integral form of equations of motion. Radial and longitudinal temperature distributions are considered while pressure distribution and geometric imperfection variations are found to be in longitudinal direction, only. The final...
On the Stability of Rotating Cylinder Conveying Flow in an External Fluid Medium
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firoozabadi, Rouhollah (Supervisor)
Abstract
The present study aims at investigating the stability of flexible spinning cylinders conveying flow in an external fluid Medium. Using the linearized Navier-Stokes equations for the flow, a two-dimensional model is developed governing the fluid motion. The resultant force exerted on the flexible cylinder wall due to the fluid interactions is calculated as a function of the lateral acceleration. Applying the Hamilton principle, the governing equations of flexural vibration of the rotary flexible cylinder mounted on simply supported axles are derived. Having the forces due to the conveying fluid calculated and substituting into the governing equations, a coupled field governing equations of...
Developing the Nonlinear Model of Single-Cell Thin-Walled Closed-Section Composite Beams
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firoozabadi, Rouhollah (Supervisor)
Abstract
The purpose of this study is to develop the reduced order nonlinear modeling of single cell closed section thin walled composite beams. In this way, global behavior of one dimensional beam under axial load, bending and torsional moment is produced. This model is based on the classical lamination theory, and the nonlinear model is developedby usingthe von-karman strains. In this process the effects of material anisotropy and axial warping are considered. Numerical results are obtained for thin-walledcomposites box beams, addressing the effects of fiber angle and laminate stacking sequence. The nonlinear model is compared with theoretical results of homogeneous beams and the natural...
Free Vibration and Aeroelastic Stability Analysis of Truncated Conical Panels in Supersonic Flows
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firoozabadi, Rouhollah (Supervisor)
Abstract
The current study is dedicated to free vibration and Aeroelastic Stability Analysis of Truncated Conical Panels in Supersonic Flows. Governing equations of motion and the corresponding boundary conditions are derived using Hamiltonian formulations. The aeroelastic stability problem is formulated based on first-order shear deformation theory as well as classical shell theory with the linearized first-order piston theory for aerodynamic loading and solved using Galerkin method. The flutter boundaries are obtained for truncated conical shells with different semi-vertex cone angles, different subtended angles, and different thickness
Numerical Simulation of Drug Delivery to Cancerous Tumors
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firoozabadi, Bahar (Supervisor)
Abstract
The tumor is a collection of cells (cell mass) caused by the lack or ineffectiveness of cellular proliferation inhibitors. Many types of cancers are associated with the emergence of a tumor, a tissue with specific physiological characteristics. The tumors grow very fast so researchers try to prevent their growth and eventually destroy them. Thermal ablation by MWA(microwave ablation) is a common and minimally-invasive treatment for primary and secondary liver tumors that can not be cured by surgery. During treatment, the tissue is heated by microwaves and at a temperature higher than 50 degree Celsius, destroyed by thermal ablation. In this study, two thermal models have been used to...
Experimental Investigation of Surfactant Effects on Dripping to Jetting Transition
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firoozabadi, Bahar (Supervisor)
Abstract
Liquid droplets are a natural phenomenon with a wide applications in various fields, including food, pharmaceutical and agricultural industries. There are two regimes in the drop falling from a nozzle, dripping and jetting regimes. The size of the formed droplet and its geometry are influenced by the formation regime. One of the most challenging problems in this field is the transition from dripping regime to jetting regime. A common method of controlling of dripping to jetting transition ( DJT1 ) is the addition of surfactant. Surfactants are substances whose molecules have a hydrophobic tail and a hydrophilic head and reduce the surface tension of a liquid by adsorbing it. In this study,...
Fabrication and evaluation of in vitro studies of biodegradable and antibacterial composite scaffolds based on polylactic acid-polycaprolactone-hydroxyapatite reinforced with graphene and zinc oxide nanoparticles for use in orthopedic surgery
, Article Iranian Journal of Materials Science and Engineering ; Volume 19, Issue 2 , 2022 , Pages 1-19 ; 17350808 (ISSN) ; Saadatabadi, A. R ; Asefnejad, A ; Sharif University of Technology
Iran University of Science and Technology
2022
Abstract
Introduction: Fabrication of fully optimized tissue-engineered materials in order to simulating the natural structure, and enhancing the biological properties of damaged tissue is one of the major challenges in biomedical engineering and regeneration medicine. Although polymeric based membranes have revealed noticeable advancements in bone regeneration, their mechanical stiffens, electrical conductivity and bioactivity need to be tolerated. Methods: Therefore, the present study is designed to generate a multifunctional biomaterial based on polylactic acid (PLA)/ polycaprolactone (PCL)/hydroxyapatite (HA) nanocomposite containing zinc oxide (ZnO) and Graphene (Gr) nanoparticles employing...
Improving cell proliferation using polylactic acid, polycaprolactone, hydroxyapatite and zinc oxide nanocomposite for cancellous bone substitutes
, Article Polymer-Plastics Technology and Materials ; Volume 63, Issue 2 , 2023 , Pages 95-119 ; 25740881 (ISSN) ; Ramazani Saadatabadi, A ; Asefnejad, A ; Sharif University of Technology
Taylor and Francis Ltd
2023
Abstract
Different types of implants are used in orthopedic applications. Due to the stress shielding and a second surgery caused by applying metal implants as orthopedic joints, using biodegradable bone implants with antibacterial properties is advantageous. Therefore, this study aims at fabricating a multifunctional poly (lactic acid) (PLA)-polycaprolactone (PCL)-based scaffold reinforced with hydroxyapatite (HA) and zinc oxide (ZnO) nanoparticles. Solvent casting combined with die-casting techniques was employed for fabricating the scaffolds, and their physical, mechanical, and biological properties were characterized. The morphology of the samples and the growth of hydroxyapatite crystals on the...
Simulation of Vortex Induced Vibration and Limit Cycle Oscillation on Flexible tall towers and Suspended Cables
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firoozabadi, Rouhollah (Supervisor)
Abstract
Vibration of flexible slender structures under vortex induced vibrations is one of the important subjects in the different fields of engineering such as overhead electricity transmission cables, columns, tall towers and suspended bridges. During passes of flow around bluff bodies, in the certain range of velocity, the Von Karman vortices sheds unsynchronized from two sides of bluff bodies. When structure frequency closed to the vortex shedding frequency, resonant vibrations happen and one can observe vibrations with limited amplitude. Simulations of these phenomenons are so complicated and time consuming prosess, but there is an engineering method for simulating this phenomenon. The aim of...
Investigation of Energy Harvesting from a Fluttering Plate in Subsonic Flow via Piezoelectric Materials
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firoozabadi, Rouhollah (Supervisor)
Abstract
One can use the vibrational energy available in environment to harvest energy via piezoelectric materials, for various applications and this research field has received growing attention by researchers over the last years. This research motivation is, harvesting electrical energy from a fluttering plate in 2D axial flow via piezoelectric materials. For this purpose, a nonlinear Euler-Bernoulli beam model is used to model structure, an incompressible 2D vortex lattice method is used to model the aerodynamics, and coupled linear piezoelectric electro-mechanical equations is used to model piezoelectric materials. The structure is considered into axial flow, and flow speed gradually increases,...
On the Flutter of Swept Taper Wing in Subsonic Compressible Flow Considering Effect of Fuel Sloshing in External Stores
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firoozabadi, R (Supervisor)
Abstract
In the present work, the aeroelastic stability analysis for the swept taper wing and external fuel tank combination system in subsonic compressible flow are represented. The wing structure is modeled by using the Euler-Bernoulli beam theory. Fuel sloshing is modeled by using an equivalent mechanical mass-spring-damper model. Modal analysis technique is used to drive the structural equations of motion of the system. Aeorodynamic of wing is modeled by using index aerodynamic that has been dived by Marzocca and a slender body aerodynamic theory for the external fuel tank are used. For stability analysis, k-method redrived for a case that structural damping there is. The effects of the external...
Natural Vibrations of Nanostructures Using a Developed 3D Model Based on Nonlocal Theory of Elasticity
,
M.Sc. Thesis
Sharif University of Technology
;
Dehghani Firoozabadi, Rouhollah
(Supervisor)
Abstract
The goal of this thesis is to survey natural frequencis of nanostructures such as nanobeams and nanoplates using nonlocal theory of elasticity by finite element method. In nonlocal theory of elasticity,the constitutive relation appears as an integral form so that the stress of a point is a function of the strain of all points in the field such that by getting away from the assumed point, the effect of strains on the stress of that point decreases. In fact, the stress on a point is an average of stress in the field and the effect of stress of other points in determined by a function called the kernel function. In order to achieve natural frequencies and shape modes of a structure, we need to...
Nonlinear Vibration Analysis of a Closed Ends ,Fluid-Filled Beam with Different Boundary Condition, Using Galerkin Method
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firoozabadi, Rouhollah (Supervisor)
Abstract
Presence of fluid in closed ends beam can increase beam hardness against pressure and buckling loads. This behavior is due to incompressibility or very low compressibility of fluids. there is a lot of research in the literature focusing on fluid solid interaction in pipe flow, but there is not any reported research studying on fluid filled beam, where fluid doesn’t flow across the beam. In this research hollow beam is modeled with Euler -Bernoulli beam theorem. Potential energy and kinetic energy is derived with considering the incompressibility of fluid. Nonlinear system of equations is derived using Hamilton principle . this system is taken to time domain using Galerkin and assumed mode...
Acoustoelastic Simulation of Baffled Container Using Boundary Element Method
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor) ; Dehghani Firoozabadi, Rouhollah (Co-Advisor)
Abstract
In this project, the acoustoelastic simulation of baffled cavities using boundary element method is investigated. At first step, the acoustic field for an enclosed rigid cavity with baffle is formulated and then solved by dual reciprocity boundary element method. In order to derive the governing equation, the acoustic domain is considered without mean flow and the fluid is assumed to be compressible and inviscid. Using the developed model and applying the zoning method, behavior and response of baffled cavities are investigated. In order to study the structure_acoustic interaction, modal reduced order model is used to explain the vibration of structure in combination to acoustic field. The...
Dynamic and Static Instability of Conical Shells Made of FGM and Conveying Hot Flow
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor) ; Dehghani Firoozabadi, Rouhollah (Supervisor)
Abstract
Static and dynamic instability of truncated conical shells made up of functionally graded materials (FGMs) conveying hot fluid is presented in this paper. Temperature-dependent material properties are considered and Material properties of the truncated FGM conical shells are functionally graded in the thickness direction according to a volume fraction power-law distribution. Governing equation of FGM conical shells is written based on First-Order Shear Deformation Theory (FSDT). The treatment is developed within the theory of linear elasticity, when materials are assumed to be isotropic and inhomogeneous through the thickness direction. The two-constituent functionally graded shell consists...
Vibration and Stability Analysis of Multiwall Carbon Nanocones on Elastic Foundation Using Nonlocal Theorem
, Ph.D. Dissertation Sharif University of Technology ; Haddadpour, Hassan (Supervisor) ; Dehghani Firoozabadi, Rouhollah (Supervisor)
Abstract
Carbo nanocones are one of the nanostructures that are investigated and takes a large deal of attention in nanotechnology. In the present study the governing equilibrium equations of motion of carbon nanotubes under external pressure are derived using a nonlocal shell model and first order shear deformation theory. The natural frequency and buckling load are extracted using modal method along with Galerkin technique.Afterthis using both Winkler and Pasternak elastic foundation models, the governing equations of motion of nanocones embedded in the elastic medium extracted using a novel approach with the nonlocal shell model along with Hamilton’s principle. These equations solved using...
On The Stability of Spinning Composite Cylindrical Shells Partially Filled With Liquid
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor) ; Dehghani Firoozabadi, Rohollah (Supervisor)
Abstract
In the present project an analytical model is proposed for the instability of spinning composite cylindrical shells partially filled with fluid. For this purpose, using the linearized Navier-Stokes equation for the incompressible flow, a 2-D model is developed for fluid motion at each section of the cylinder. The resultant pressure exerted on the cylinder wall as the result of the fluid motion, are calculated in terms of elastic displacements of the cylinder. Applying the Hamilton principle, the governing equations of motion of the cylinder are derived and then combined with the equations describing the fluid pressure to obtain the coupled-field equations of the structural-fluid motion....
An efficient tabu search algorithm for the single row facility location problem [electronic resource]
, Article European Journal Of Operational Research ; Vol. 205, No. 1, pp. 98-105 ; Eshghi, Kourosh ; Sharif University of Technology
Abstract
The general goal of the facility layout problem is to arrange a given number of facilities to minimize the total cost associated with the known or projected interactions between them. One of the special classes of the facility layout problem is the Single Row Facility Layout Problem (SRFLP), which consists of finding an optimal linear placement of rectangular facilities with varying dimensions on a straight line. This paper first presents and proves a theorem to find the optimal solution of a special case of SRFLP. The results obtained by this theorem prove to be very useful in reducing the computational efforts when a new algorithm based on tabu search for the SRFLP is proposed in this...
Sensitivity analysis of matching pennies game [electronic resource]
, Article Mathematical and Computer Modelling ; Volume 51, Issues 5–6, March 2010, Pages 722–735 ; Eshghi, Kourosh ; Sharif University of Technology
Abstract
In this paper, we have discussed the results of sensitivity analysis in a payoff matrix of the Matching Pennies game. After representing the game as a LP model, the sensitivity analysis of the elements of the payoff matrix is presented. The game value and the optimal strategies for different values of parameters are determined and compared