CMB Lensing and Large Scale Structure Bias as a Probe of Beyond and CDM Cosmology

, M.Sc. Thesis Sharif University of Technology Hassani, Farbod (Author) ; Baghram, Shant (Supervisor) ; Firouzjahi, Hassan (Supervisor)

Abstract

The standard model of Cosmology known as CDM is established as a cornerstone of modern cosmology. The Cosmic Microwave Background radiation (CMB) and Large Scale Structure (LSS) Observations indicate that almost all observations can be described by a 6-parameter standard model with an initial condition of almost Gaussian, isotropic, scale invariant and adiabatic which can be sourced by inflationary models. Recent observations of Planck collaboration shows almost no deviation from standard picture of single field slow roll inflation. Despite the success of the standard model, the physics of early universe, the nature of dark matter and dark energy is still unknown. The large scale structure...

Primordial Dipole Anisotropy on the Cosmic Microwave Background and Inflation Theory

, M.Sc. Thesis Sharif University of Technology Jazayeri, Sadra (Author) ; Mansouri, Reza (Supervisor) ; Firouzjahi, Hassan (Supervisor)

Abstract

Cosmic Inflation, invented by Alan Guth in 1980’s, solves the shortcomings of the Standard Cosmology such as the flatness, the horizon and the monopoles problems and provides the seeds of large scale structure formation. The quantum fluctuations which are produced during inflationary epoch are redshifted and transferred from Microscopic scales to Macroscopic universe. We can observe this macroscopic fluctuations both on the CMB surface and on large scale structures. Data from WMAP and Planck missions(CMB space Telescopes) suitably confirms the general predictions of single field inflationary scenarios but still people search for finding primordial gravitational waves from the B-Mode signal...

Effective Field Theory of Inflation and its Applicationin Calculating Primordial Non-Gaussianities

, M.Sc. Thesis Sharif University of Technology Vakili, Mohammad Javad (Author) ; Golshani, Mahdi (Supervisor) ; Firouzjahi, Hassan (Supervisor)

Abstract

In this thesis we perform the method for calculating primordial non- Gaussianity for a generic single-field inflationary model and compare the results of important models such as DBI inflation and slow roll inflation. Then, we will show how to extract potentially observable quantities from 3 point correlation functions of gauge invariant curvature perturbations, like the size and shape of non-Gaussianities. Then,we will review the effective field theory approach to inflation that allows us to unify all inflationary models and characterize high energy corrections to simple slow roll model. We use this approach to estimate the size of non-Gaussianities in various limit. Furthermore, we study...

Large Scale Structures as a Probe of Physics of Early Universe

, M.Sc. Thesis Sharif University of Technology Ansarifard, Mohammad (Author) ; Baghram, Shant (Supervisor) ; Firouzjahi, Hassan (Co-Advisor)

Abstract

The standard model of cosmology with nearly Gaussian, isotropic, scale invariant and adiabatic initial conditions describes the cosmological observations. However, the study of any deviation from the mentioned conditions will open up a new window to the physics of early universe. In this work we study the effect of the oscillatory and step in potential inflationary models in late time large scale structure observations. Almost we study the matter power spectrum, number density of the structures, the halo bias an the bulk flow in mentioned models. We assert that inflationary models with step functions which deviates from the standard model in small scales l ≤ 1Mpc can be confirmed by Large...

The Effects of Tachyonic Instabilities and Non-Gaussian Perturbations During Cosmic Inflation and Reheating

, Ph.D. Dissertation Sharif University of Technology Abolhasani, Ali Akbar (Author) ; Firouzjahi, Hassan (Supervisor) ; Golshani, Mehdi (Co-Advisor) ; Sheikh Jabbari, Mohammad Mahdi (Co-Advisor)

Abstract

The cosmic inflation paradigmwas first introduced as a possible solution to the standardBig Bang cosmology problems. [1]. The inflationary models not only provide a solutionfor so the called flatness and horizon problems, but also they predict perturbations asprimordial seeds of large scale structures of Universe. Inflationary models can connecthigh-energy physics to the experiments. There is a mutual relation between inflationand high energy physics. It is necessary to find a fundamental description of inflationarymechanism and on the other hand the observational predictions of inflationary modelscan put bound on free parameters of associated fundamental theories. Thanks to vastdata...

Lensing as a probe of early universe: From CMB to galaxies

, Article Journal of Cosmology and Astroparticle Physics ; Volume 2016, Issue 5 , 2016 ; 14757516 (ISSN) Hassani, F ; Baghram, S ; Firouzjahi, H ; Sharif University of Technology

Institute of Physics Publishing 2016

Abstract

The Cosmic Microwave Background (CMB) radiation lensing is a promising tool to study the physics of early universe. In this work we probe the imprints of deviations from isotropy and scale invariance of primordial curvature perturbation power spectrum on CMB lensing potential and convergence. Specifically, we consider a scale-dependent hemispherical asymmetry in primordial power spectrum. We show that the CMB lensing potential and convergence and also the cross-correlation of the CMB lensing and late time galaxy convergence can probe the amplitude and the scale dependence of the dipole modulation. As another example, we consider a primordial power spectrum with local feature. We show that...

Statistical anisotropies in gravitational waves in solid inflation

, Article Journal of Cosmology and Astroparticle Physics ; Vol. 2014,Issue. 9 , 2014 ; ISSN: 14054179 Akhshik, M ; Emami, R ; Firouzjahi, H ; Wang, Y ; Sharif University of Technology

2014

Abstract

Solid inflation can support a long period of anisotropic inflation. We calculate the statistical anisotropies in the scalar and tensor power spectra and their cross-correlation in anisotropic solid inflation. The tensor-scalar cross-correlation can either be positive or negative, which impacts the statistical anisotropies of the TT and TB spectra in CMB map more significantly compared with the tensor self-correlation. The tensor power spectrum contains potentially comparable contributions from quadrupole and octopole angular patterns, which is different from the power spectra of scalar, the cross-correlation or the scalar bispectrum, where the quadrupole type statistical anisotropy dominates...

Primordial statistical anisotropies: the effective field theory approach

, Article Journal of Cosmology and Astroparticle Physics ; Volume 2016, Issue 3 , 2016 ; 14757516 (ISSN) Abolhasani, A. A ; Akhshik, M ; Emami, R ; Firouzjahi, H ; Sharif University of Technology

Institute of Physics Publishing 2016

Abstract

In this work we present the effective field theory of primordial statistical anisotropies generated during anisotropic inflation involving a background U(1) gauge field. Besides the usual Goldstone boson associated with the breaking of time diffeomorphism we have two additional Goldstone bosons associated with the breaking of spatial diffeomorphisms. We further identify these two new Goldstone bosons with the expected two transverse degrees of the U(1) gauge field fluctuations. Upon defining the appropriate unitary gauge, we present the most general quadratic action which respects the remnant symmetry in the unitary gauge. The interactions between various Goldstone bosons leads to...

Inflationary power asymmetry from primordial domain walls

, Article Journal of Cosmology and Astroparticle Physics ; Vol. 2014, issue. 11 , 2014 ; ISSN: 14757516 Jazayeri, S ; Akrami, Y ; Firouzjahi, H ; Solomon, A. R ; Wang, Y ; Sharif University of Technology

2014

Abstract

We study the asymmetric primordial fluctuations in a model of inflation in which translational invariance is broken by a domain wall. We calculate the corrections to the power spectrum of curvature perturbations; they are anisotropic and contain dipole, quadrupole, and higher multipoles with non-trivial scale-dependent amplitudes. Inspired by observations of these multipole asymmetries in terms of two-point correlations and variance in real space, we demonstrate that this model can explain the observed anomalous power asymmetry of the cosmic microwave background (CMB) sky, including its characteristic feature that the dipole dominates over higher multipoles. We test the viability of the...

Structural Design of a Launch Vehicle with Reusable First Stage

, M.Sc. Thesis Sharif University of Technology Hassan Jamaklu (Author) ; Haddadpour, Hassan (Supervisor)

Abstract

Aerodynamics loads and aeroheating during reentry, are one of the challenging issues in designing One of the main challenges in the design and application of reusable spacecrafts is the aerodynamic and thermal loads acting on their structures during reentry into the atmosphere. For this reason, all the concepts/prototypes presented in the 20th century were either not fully reusable, or were partially canceled, or did not have economic justification. In this report, the aerodynamic loads on the first stage of a launch vehicle during the launch and return phases have been investigated. Due to the fact that the main part of the first stage of the vehicle includes fuel and oxidizer tanks, the...

Expected dipole asymmetry in CMB polarization

, Article Journal of Cosmology and Astroparticle Physics ; Volume 2015, Issue 5 , May , 2015 ; 14757516 (ISSN) Namjoo, M. H ; Abolhasani, A. A ; Assadullahi, H ; Baghram, S ; Firouzjahi, H ; Wands, D ; Sharif University of Technology

Institute of Physics Publishing 2015

Abstract

We explore the hemispherical asymmetry predicted in cosmic microwave background polarization when there is an asymmetry in temperature anisotropies due to primordial perturbations. We consider the cases of asymmetries due to adiabatic and isocurvature modes, and tensor perturbations. We show that the asymmetry in the TE, EE and/or BB correlations can be substantially larger than those in the TT power spectrum in certain cases. The relative asymmetry in the different cross-correlations, as well as the angular scale dependence, can in principle distinguish between different origins for the asymmetry

Optimal Trajectory Correction for Hazardous Near-Earth Asteroids

, M.Sc. Thesis Sharif University of Technology Farsi, Salman (Author) ; Zohoor, Hassan (Supervisor) ; Sayyadi, Hassan (Supervisor)

Abstract

The collision of moderately large asteroids and comets also referred to as Near-Earth Objects (NEO's) with earth would have catastrophic consequences. Such events have occurred in the past and may occur again in the future. However, for the first time in known history, humanity may have the technology required to counter this threat. Methods studied for mitigation of this hazard are based on deflecting asteroid's trajectory and are normally divided into two basic categories: high energy impulsive methods, and long-duration low-thrust methods. Two parts of mission to be optimized are the trajectory of spacecraft to reach the target and the deflection strategy which could be analyzed by the...

A revised version of ACO for cutting stock problem [electronic resource]

, Article International Journal of Industrial Engineering ; Vol 15, No 4 (2008), Pages 341-348 Eshghi, K. (Kourosh) ; Javanshir, Hassan ; Sharif University of Technology

Abstract

The one-dimensional cutting stock problem has many applications in industries and during the past few years has been one of the centers of attention among the researchers in the field of applied operations research. In this paper, a revised version of Ant Colony Optimization (ACO) technique is presented to solve this problem. This paper is a sequel to the previous ACO algorithm presented by the authors. In this algorithm, according to some probabilistic rules, artificial ants will select cutting patterns and generate a feasible solution. Computational results show the high efficiency and accuracy of the proposed algorithm for solving one- dimensional cutting stock problem

Control of Car-Like Multi Robots for Following and Hunting of Moving Target

, M.Sc. Thesis Sharif University of Technology Kouhi Gilvan, Hamed (Author) ; Sayyaadi, Hassan (Supervisor) ; Salarieh, Hassan (Co-Advisor)

Abstract

The main purpose of the present thesis is to establish a decentralized controller for some car–like multi robots to follow and hunt moving targets. Robots are very similar to actual cars considering geometric dimensions, mass and moment of inertia and so on; and outputs of the controller are steering-wheel and driving-wheel torques appropriately. Dynamics of the moving target is so that it escapes from the robots. Robots are equipped with antenna for getting wireless sensory signals, including range and bearing sensors. Kalman filter is used for estimation the target relative position and speed and robots state variables. The controller is designed for doing the above mentioned group...

Stock Price Forecasting Using Neural Networks and Fuzzy Logic

, M.Sc. Thesis Sharif University of Technology Alizadeh, Parisa (Author) ; Shavandi, Hassan (Supervisor)

Abstract

This research proposes a novel hybrid method for stock price index forecasting relying on technical analysis, the fundamental analysis of capital market, neural networks technology, and fuzzy logic. The new method shows a good performance comparing complicated and time-consuming forecasting methods. Several factors influence stock price; for example, an important one is the previous trend of stock price. Fortunately, by developing technical analysis and introducing the various indices of this method the maximum use of historical data is made in order to forecast future prices. Another kind of factors is macro-economic variables that their influence on the long-term trends of the stock...

Control of a Group of Mobile Manipulators for Cooperative object Transportation

, M.Sc. Thesis Sharif University of Technology Babaee, Mohammad (Author) ; Sayyadi, Hassan (Supervisor)

Abstract

In this thesis control of wheeled mobile manipulators for cooperative object transportation is investigated. Full dynamic model of a mobile manipulator with a three wheeled mobile base and a three DOF manipulator is derived using Gibbs-Appell method. Input-output linearization technique is used to control individual robots. Transporting the object is divided into two steps, first robots use a decentralized behavior-based method to approach and surround the object. Then virtual structure method is used to control the robots to transport the object cooperatively. Simulation results with three robots handling an object are presented to show the effectiveness of proposed method

Dynamic and Control of Tethered Satellite Systems

, M.Sc. Thesis Sharif University of Technology Yousefian, Peyman (Author) ; Salarieh, Hassan (Supervisor)

Abstract

In this work dynamic behavior of a two body TSS with main satellite as rigid body is studied and effects of tether elasticity and tension on the satellite dynamic are indicated in station keeping phase and circular orbit. Also a simplified modeling is introduced which could be used in nonlinear controller design. Lagrange and extended Lagrange method is used to derive equations of motion. It is shown that longitudinal vibration of tether has small effect on satellite attitude and angular velocity and because of high frequency it can be decoupled from satellite dynamic. In the simplified model, orbital motion is decoupled from equations of TSS and main satellite dynamic. Effect of decoupling...

Analysis of Control of Nonlinear Switched Systems

, M.Sc. Thesis Sharif University of Technology Toorani, Amin (Author) ; Zohoor, Hassan (Supervisor)

Abstract

Separate analysis of modern systems by continuous or discrete theories is not possible, because they cannot solely express the detailed descriptions of a system. As a result of this, researchers are motivated to study hybrid systems. Specific class of hybrid systems which consists of several continuous subsystems and a rule that specifies how to switch between them, is called a switched system. Recently, many studies have been done on the stability and control of switched systems. In this regard, the goal of present study is presenting applications of switched systems using two control methods. The first application is control of a chemical reactor system with multiple modes. We presented...

Design and Analysis of a Cable Based Robot Similar to a Human Hand

, M.Sc. Thesis Sharif University of Technology Abyaneh, Soroush (Author) ; Zohoor, Hassan (Supervisor)

Abstract

The application of manipulators is becoming more and more popular in objects handling especially when it is desired to have access to remote areas in destructive or hazardous taskspaces. For this purpose, a hand-like mechanism must be designed to be used as an end-effector, which can grasp objects. In this paper a cable driven grasping mechanism has been presented. In the proposed mechanism each finger consists of three phalanxes which are actuated by a single motor. Also, locking and unlocking constraints are used in the mechanism in order to generate an anthropomorphic motion, in which, the order of reaching phalanxes to the object is sequential, in such a way that each phalanx starts...

Data Integration with Multiple Ontologies in Semantic Sensor Web

, M.Sc. Thesis Sharif University of Technology Sadeghi, Shahrouz (Author) ; Abolhassani, Hassan (Supervisor)

Abstract

Sensor Observation Service (SOS) which is defined by Open Geospatial Consortium (OGC) Sensor Web Enablement group is a Web service specification in order to standardize the way sensors and sensor data are discovered and accessed on the Sensor Web. Multiple instances of this service can be implemented around the world, providing huge amount of data every moment. Each of these services operates in specific domain of knowledge (thematic), spatial and temporal dimensions. One way to reveal the underlying data over all of them is to provide an architecture for data integration to allow the user to query sensor data without the knowledge of the infrastructure components. In this research, a novel...