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The Effect of Second Order Dissipation on the Sound Velocity in Quasi-QCD Plasma Using the Effective Potential of the Linear Sigma Model
, M.Sc. Thesis Sharif University of Technology ; Sadooghi, Neda (Supervisor)
Abstract
The heavy ion collision experiments are in progress in order to investigate how the Universe has evolved after the Big Bang. The recent observations show that a nearly perfect fluid is produced after heavy ion collisions. An appropriate incorporation of the relativistic hydrodynamics and the field theory would help us to describe the dynamics of QCD (Quantum Chromodynamics) matter under extreme conditions, and to survey the expected phase transitions. The majority of efforts to investigate the characteristics of the QCD plasma are devoted to an ideal, non-dissipative one. To get the results which are highly in accordance with the experiment, it is necessary to bring also in mind the role of...
The Kinetic Term of the Effective Action in the NJL Model in Background Magnetic Field at Finite Temperature and Chemical Potential
, M.Sc. Thesis Sharif University of Technology ; Sadooghi, Neda (Supervisor)
Abstract
Kinetic terms of effective action including derivative of classical field become significant, when we have a dynamical field.These terms have been calculated as a function of the fermionic propagator in NJL model, which is an effective model of QCD. In this thesis, after briefly reviewing
the effect of constant background magnetic field on the propagator considered by Ritus method, we explicitly determine the kinetic terms in terms of Ritus eigenfunctions. Finally, we numerically calculate these terms at finite temperature and chemical potential according to the imaginary time method
the effect of constant background magnetic field on the propagator considered by Ritus method, we explicitly determine the kinetic terms in terms of Ritus eigenfunctions. Finally, we numerically calculate these terms at finite temperature and chemical potential according to the imaginary time method
Effect of the Fluctuations of Quantum Chromodynamics Topological Charge on the Dispersion Relation of NJL Model
, M.Sc. Thesis Sharif University of Technology ; Sadooghi, Neda (Supervisor)
Abstract
One of the long-lived problems in the theory of quantum chromo dynamics is the violation of parity (P) and charge-parity (CP) symmetries in strong interactions. The existence of gluon configurations sourcing from topology leads to degeneracy in the vacuum structure of the theory. This phenomenon is realized by the addition of an extra term proportional to the parameter to QCD Lagrangian. Experimental estimates of neutron electric dipole, predicts a very small value for this parameter. There is no verified justification for this discrepancy. Recently at the relativistic heavy ion collider laboratory (RHIC) some experimental evidence has been found which indicates local CP violation in...
Shear Viscosities of a Hot Fermi Gas in the Presence of a Strong Magnetic Field
, M.Sc. Thesis Sharif University of Technology ; Sadooghi, Neda (Supervisor)
Abstract
Relativistic hydrodynamics and kinetic theory are often used to analyze the experimental data from heavy ion collisions. One of the most important observations is the anisotropy in the number density of the detected particles after the collision in the longitudinal and perpendicular directions with respect to the reaction plane. On the other hand, very strong magnetic fields are created during the early stages of non-central heavy ion collisions. The presence of constant background magnetic fields, aligned in the perpendicular direction to the reaction plane, can be one of reasons for the aforementioned anisotropy in the number density of detected particles. In this thesis, we study the...
Evolution of Electromagnetic Fields in a Plasma of Quarks and Gluons
, Ph.D. Dissertation Sharif University of Technology ; Sadooghi, Neda (Supervisor)
Abstract
In heavy ion collisions, extremely large electromagnetic fields are produced by fast-moving charged nucleons. They are sufficiently large to affect the low energy QCD processes and thus produce observable effects, whose occurrence is, however, directly related to the lifetime of these fields. In the present dissertation, the evolution of electromagnetic fields is studied in a plasma of quarks and gluons, by analytically solving the equations of relativistic magnetohydrodynamics (RMHD). The onideal Bjorken RMHD is solved by introducing the method of nonconserved charges. Assuming an electromagnetic force-free condition, the electric and magnetic fields are found to be either parallel or...
On the Effects of Background Electromagnetic elds and Chiral Chemical Potential on the Phase Diagram of Quantum Chromodynamics
, M.Sc. Thesis Sharif University of Technology ; Sadooghi, Neda (Supervisor)
Abstract
In particle physics, spontaneous chiral symmetry breaking generates new phases of quark matter, and leads to significant changes od quark masses. The Nambu-Jona–Lasinio (NJL) model is a useful fermionic model which describes the spontaneous chiral symmetry breaking through the creation of a condensate. This model can be for instance used to determine various phases of Quantum Chromodynamics (QCD) in finite electromagnetic fields. This work consists of several parts. First, we describe the spontaneous chiral symmetry breaking in detail. Second, we extract the NJL model from the Lagrangian density of QCD. Third, we derive a covariant form of the partition function of a fermionic system....
Dilepton Production and Synchrotron Radiation in a Magnetized Quark-Qluon Plasma
, M.Sc. Thesis Sharif University of Technology ; Sadooghi, Neda (Supervisor)
Abstract
Relativistic collisions of heavy ions lead to the formation of a new phase of matter called Quark-Gluon Plasma (QGP). In addition, strong magnetic fields generates in these collisions that its direction is perpendicular to the collision axis. This strong magnetic field affects the dynamics of particles in the QGP, and causes the appearance of the Landau levels in the particle’s energy spectrum. In this master thesis, we investigate the impact of the magnetic field on dilepton production and synchrotron radiation. We calculate the scattering probability of quark and anti-quark annihilation and dilepton creation by taking all Landau Levels into account. Then, by assuming that the magnetic...
Magnetic Susceptibility of Qark Matter in the Presence of a Non-Homogeneous Magnetic Field at Finite Temperature and Chemical Potential
, M.Sc. Thesis Sharif University of Technology ; Sadooghi, Neda (Supervisor)
Abstract
After the review of formation of Landau levels (LL) in non-relativistic quantum mechanics, we have obtained LL in a certain gauge A_μ=(0,-B_0/2 y,B_0/2 x) at 2+1 &3+1 dimension. then give a summary of Quantum Field Theory at non-zero temperature . obtaining LL and two-point Green function in non-uniform magnetic field which determined with A_μ=(0,0,√qB ξe^(-(t+x) ),0).Next we calculate magnetic susceptibility of in such a field with finite chemical potential and temperature. Finally we compare the obtained results with uniform magnetic field one
Color Super Counductivity at Finite Temperature, Chemical Potential and in the Presence of Strong Magnetic Fields
, Ph.D. Dissertation Sharif University of Technology ; Sadooghi, Neda (Supervisor)
Abstract
In the present thesis, the effect of external magnetic fields on two-flavor Color Superconductive (2SC) phase, as one of the phases in the QCD phase diagram, is studied. To do this, an effective two-flavor Nambu-Jona Lasinio Lagrangian is used, which consists of two mass gaps, s = ?¯qq and ? = ? . The nonzero values of chiral and color mass these gaps induce spontaneous chiral and color symmetry breaking, and consequently two different phases. There is also a third phase, the normal phase, where s = ? = 0. We calculate the transition curves and the critical points in terms of three intensive quantities, the temperature, the chemical potential and the external magnetic field. We study, in...
On the Effects of Finite Temperature and Background Magnetic Fields on the Observables of Heavy Ion Collisions
, Ph.D. Dissertation Sharif University of Technology ; Sadooghi, Neda (Supervisor)
Abstract
The main focus of this dissertation is to investigate the effects of the created background magnetic field on some of the observables that are relevant in heavy ions experiments. Based on the phase diagram of Quantum Chromodynamics, it is expected that in extreme conditions such as high temperature or in dense medium, a new phase of matter arises, which is known as Quark-Gluon Plasma (QGP). Due to the vital role of collective behaviors, this phase behaves similar to a perfect fluid rather than a gas. In addition, the colliding nucleons have potential of creating very strong magnetic fields because of their electric charges and relativistic speeds. Therefore the investigation of the effects...
QED Ring Diagrams in Background Magnetic Field at Finite Temperature
, M.Sc. Thesis Sharif University of Technology ; Sadooghi, Neda (Supervisor)
Abstract
Using the general structure of the vacuum polarization tensor П_μν (k_0→0,k) in the infrared (IR) limit, k_0→0 , the ring contribution to the QED effective potential at finite temperature and the nonzero magnetic field is determined beyond the static limit, (k_0→0,k→0). The resulting ring potential is then studied in weak and strong magnetic field limits. In the weak magnetic field limit and at high temperature the improved ring potential consists of a term proportional to T^4 α^(5/2), in addition to the expected term T^4 α^(3/2) arising from the static limit. In the limit of the strong magnetic field, where QED dynamics is dominated by the lowest Landau level, the ring potential includes a...
On the Effect of Ring Diagrams on QCD Phase Transition
, M.Sc. Thesis Sharif University of Technology ; Sadooghi, Neda (Supervisor)
Abstract
In this thesis NJL and quark-meson models, as effective models for quantum chro-modynamics in low energies, are studied mainly. After reviewing models and phe-nomena related to the strong interaction in zero and non-zero temperature, firstly the critical coupling of NJL model for non-zero temperature and chemical potential is calculated. Then, the contribution of ring diagrams in the effective potential of quark-meson model is presented. Finaly, the effect of ring diagrams of quark-meson model on chiral phase transition is investigated. For NJL model, it is shown that the chemical potential lowers the critical coupling for chiral phase transition. Also for quark-meson model, it is shown that...
Mass-Radius Relation for a Rotating and Magnetized Neutron Star Using the Nambu-Jona-Lasinio Model
, M.Sc. Thesis Sharif University of Technology ; Sadooghi, Neda (Supervisor)
Abstract
One of the most essential concepts for describing neutron stars is investigating their radial mass distribution or mass-radius relation. The aim of this thesis is to evaluate radial mass distribution of neutron stars in the presence of magnetic fields. To achieve this objective we use the Tolman- Oppenheimer-Volkoff equation of hydrostatic equilibrium for non-rotating cases and the Hartle- Thorne equations for rotating cases. olving these equations depends on determination of equation of state of neutron star in the presence of magnetic fields. For determining the corresponding equation of state, one can use QCD-like non-perturbative models, in particular Nambu-Jona- Lasinio (NJL) model. In...
On the hysteretic behavior of trapezoidally corrugated steel shear walls
, Article Structural Design of Tall and Special Buildings ; Vol. 23, Issue. 2 , 10 February , 2014 , pp. 94-104 ; ISSN: 15417794 ; Mofid, M ; Sharif University of Technology
2014
Abstract
At present, corrugated plates have numerous applications such as web of plate girders and aerospace applications. Higher out-of-plane stiffness and initial elastic strength of the corrugated plates compared with flat plates are reasons for consideration. This study investigates the behavior of trapezoidally corrugated steel plate shear walls (TCSPSWs) under monotonic and cyclic loadings. Finite element analyses that include both material and geometric nonlinearities are employed for the examination. The results from finite element analysis are verified through tested specimen findings. Moreover, the behavior of the steel shear walls with the flat infill panels and the corrugated plate infill...
Cyclic test of steel plate shear wall designed by PFI method
, Article Advanced Materials Research ; Volume 378-379 , 2012 , Pages 785-788 ; 10226680 (ISSN) ; 9783037852880 (ISBN) ; Mofid, M ; Sharif University of Technology
2012
Abstract
In this paper, Plate Frame Interaction (PFI) developed by other researches for modeling Steel Plate Shear Wall (SPSW) is applied for designing a half-scale, single bay and one story SPSW. After designing of SPSW, one specimen is constructed accordingly. In order to determine the mechanical properties of steel, coupon test is performed; and then again theoretical relations based on PFI is re-checked. In this study, gravity loads are neglected and only seismic resistance of SPSW is considered. With cyclic lateral loading as quasi-static load, according to Acceptance Criteria for Cyclic Racking Shear Tests For Metal-Sheathed Shear Walls with Steel Framing (AC154) and obtaining its hysteretic...
Comparison of beam shapes and transmission powers of two prism ducts
, Article Australian Journal of Basic and Applied Sciences ; Volume 4, Issue 10 , 2010 , Pages 4922-4929 ; 19918178 (ISSN) ; Golnabi, H ; Sharif University of Technology
2010
Abstract
Design and performance of two-stage optical beam shaping system based on a plastic fiberbundle, prism coupled waveguide, is described in this study. Such systems offer practical means to modify and change the output beam shape at two stages and also provide quantitative information concerning the output beam intensity. It is possible to investigate output power and image transmittance data by using a light source for illumination and image analysis by a CCD/digital camera. The photograph picture of the illuminating LED beam shows a circular shape with a diameter of about 10 mm at its output point. Picture of the fiber-bundle output beam is also taken, which shows a rectangular shape with a...
On the improvement of steel plate shear wall behavior using energy absorbent element
, Article Scientia Iranica ; Volume 24, Issue 1 , 2017 , Pages 11-18 ; 10263098 (ISSN) ; Mofid, M ; Sharif University of Technology
Sharif University of Technology
2017
Abstract
Structural engineers have recognized unstiffened Steel Plate Shear Wall (SPSW) as an economical lateral resisting system due to the post-buckling capacity, energy dissipation, and deformability. This study investigates practical application of an added Energy Absorbent Element (EAE), subjoined to the SPSW in order to improve seismic behavior of the SPSW. The EAE is an aluminum shear panel with or without bracings and surrounding frame. Furthermore, a series of parametric studies are implemented to examine the effect of dimensions, position, and formation of the EAE. It is assumed that the lateral loading is applied as quasi-static loading. Further, nonlinearity of the material and the...
Intelligent trajectory tracking of an aircraft in the presence of internal and external disturbances
, Article International Journal of Robust and Nonlinear Control ; Volume 29, Issue 16 , 2019 , Pages 5820-5844 ; 10498923 (ISSN) ; Banazadeh, A ; Sharif University of Technology
John Wiley and Sons Ltd
2019
Abstract
This research deals with developing an intelligent trajectory tracking control approach for an aircraft in the presence of internal and external disturbances. Internal disturbances including actuators faults, unmodeled dynamics, and model uncertainties as well as the external disturbances such as wind turbulence significantly affect the performance of the common trajectory tracking control approaches. There are several fault-tolerant control approaches in the literature to overcome the effects of specific actuator or sensor faults during the flight. However, trajectory tracking control of an air vehicle in the presence of unexpected faults and simultaneous presence of wind turbulence is...
Online identification of aircraft dynamics in the presence of actuator faults
, Article Journal of Intelligent and Robotic Systems: Theory and Applications ; Volume 96, Issue 3-4 , 2019 , Pages 541-553 ; 09210296 (ISSN) ; Banazadeh, A ; Sharif University of Technology
Springer
2019
Abstract
In this paper, a multiple model-based nonlinear identification approach is introduced for a conventional aircraft in the presence of different types of actuator faults. Occurrence of actuator faults can obviously reduce the validity of a predetermined dynamic model of nonlinear systems. In such cases, use of multi-model structures can be an effective choice. However, determining the optimal validity functions of the local models in a multi-model structure is still a challenging problem. This problem becomes even more challenging in case of unpredictable faults, which are not considered in training the local models. In this paper, two effective techniques are proposed for online determination...
Thermodynamic Analysis of the Temporal Changes in Salt Concentration in Saline Lakes (the case of Urmia lake)
, M.Sc. Thesis Sharif University of Technology ; Tajrishi, Masoud (Supervisor)
Abstract
Urmia Lake is a strong electrolyte containing various salts, with a thermodynamic identity. Changes in the temperature and volume of lake water cause a change in the concentration of ions in this brine as well as the composition and precipitation of salts in the lake. As a result of these changes, the thermodynamic properties of brine are also changed. The purpose of this study was to investigate the effect of mixing the rivers entering the lake and calculate and analyze the changes in the quality and hydrogeochemical characteristics of Urmia Lake and the amount of precipitation and dissolution of the main minerals in Urmia Lake during the period of 2007-2013 per month. For this purpose,...