Advanced Electromagnetics and Scattering Theory

, Book Barkeshli, Kasra ; Khorasani, Sina

Springer 2015

Abstract

This book present the lecture notes used in two courses that the late Professor Kasra Barkeshli had offered at Sharif University of Technology, namely, . The prerequisite for the sequence is vector calculus and electromagnetic fields and waves. Some familiarity with Green's functions and integral equations is desirable but not necessary.
The book provides a brief but concise introduction to classical topics in the field. It is divided into three parts including annexes. Part I covers principle of electromagnetic theory. The discussion starts with a review of the Maxwell's equations in differential and integral forms and basic boundary conditions. The solution of inhomogeneous wave...

Coordinating a seller-buyer supply chain with a proper allocation of chain’s surplus profit using a general side-payment contract [electronic resource]

, Article International Journal of Industrial and Systems Engineering ; Volume 5, No. 2, Summer 2011, Page 63-79 Masihabadi, S. (Sina) ; Eshghi, Kourosh ; Sharif University of Technology

Abstract

In this paper, seller-buyer supply chain coordination with general side-payment contracts is introduced to gain the maximum possible chain profit. In our model, the logistics costs for both buyer and seller are considered and the final demand is also supposed to be a decreasing function of the retail price. Since parties aim to maximize their individual profits, the contractual parameters are set in a way that these decisions become aligned with system optimal decisions. Therefore, a side payment contract is suggested in our model to assign the chain surplus profit to the chain members such that they have no intention to leave the coalition. Then, we change the contract into a quantity...

Recovery of low-rank matrices under affine constraints via a smoothed rank function

, Article IEEE Transactions on Signal Processing ; Vol. 62, Issue. 4 , 15 February , 2014 , pp. 981-992 ; ISSN: 1053587X Malek-Mohammadi, M ; Babaie-Zadeh, M ; Amini, A ; Jutten, C ; Sharif University of Technology

2014

Abstract

In this paper, the problem of matrix rank minimization under affine constraints is addressed. The state-of-the-art algorithms can recover matrices with a rank much less than what is sufficient for the uniqueness of the solution of this optimization problem. We propose an algorithm based on a smooth approximation of the rank function, which practically improves recovery limits on the rank of the solution. This approximation leads to a non-convex program; thus, to avoid getting trapped in local solutions, we use the following scheme. Initially, a rough approximation of the rank function subject to the affine constraints is optimized. As the algorithm proceeds, finer approximations of the rank...

SRF: Matrix completion based on smoothed rank function

, Article ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings, 22 May 2011 through 27 May 2011, Prague ; 2011 , Pages 3672-3675 ; 15206149 (ISSN) ; 9781457705397 (ISBN) Ghasemi, H ; Malek-Mohammadi, M ; Babaie-Zadeh, M ; Jutten, C ; Sharif University of Technology

2011

Abstract

In this paper, we address the matrix completion problem and propose a novel algorithm based on a smoothed rank function (SRF) approximation. Among available algorithms like FPCA and OptSpace, there is no solution that can simultaneously cover wide range of easy and hard problems. This new algorithm provides accurate results in almost all scenarios with a reasonable run time. It especially has low execution time in hard problems where other methods need long time to converge. Furthermore, when the rank is known in advance and is high, our method is very faster than previous methods for the same accuracy. The main idea of the algorithm is based on a continuous and differentiable approximation...

Multi-antenna assisted spectrum sensing in spatially correlated noise environments

, Article Signal Processing ; Volume 108 , December , 2015 , Pages 69-76 ; 01651684 (ISSN) Koochakzadeh, A ; Malek Mohammadi, M ; Babaie Zadeh, M ; Skoglund, M ; Sharif University of Technology

Elsevier 2015

Abstract

A significant challenge in spectrum sensing is to lessen the signal to noise ratio needed to detect the presence of primary users while the noise level may also be unknown. To meet this challenge, multi-antenna based techniques possess a greater efficiency compared to other algorithms. In a typical compact multi-antenna system, due to small interelement spacing, mutual coupling between thermal noises of adjacent receivers is significant. In this paper, unlike most of the spectrum sensing algorithms which assume spatially uncorrelated noise, the noises on the adjacent antennas can have arbitrary correlations. Also, in contrast to some other algorithms, no prior assumption is made on the...

Upper bounds on the error of sparse vector and low-rank matrix recovery

, Article Signal Processing ; Volume 120 , 2016 , Pages 249-254 ; 01651684 (ISSN) Malek Mohammadi, M ; Rojas, C.R ; Jansson, M ; Babaie Zadeh, M ; Sharif University of Technology

Elsevier 2016

Abstract

Suppose that a solution x to an underdetermined linear system b=Ax is given. x is approximately sparse meaning that it has a few large components compared to other small entries. However, the total number of nonzero components of x is large enough to violate any condition for the uniqueness of the sparsest solution. On the other hand, if only the dominant components are considered, then it will satisfy the uniqueness conditions. One intuitively expects that x should not be far from the true sparse solution x0. It was already shown that this intuition is the case by providing upper bounds on ||x-x0|| which are functions of the magnitudes of small components of x but independent from x0. In...

Photonic Crystal Cavity Quantum Optic in the Very Strong Coupling Regime

, M.Sc. Thesis Sharif University of Technology Ahmadi, Elaheh (Author) ; Khorasani, Sina (Supervisor)

Abstract

First, we peruse the intraction between a quantized light and a two level atom which has been described by Janes-Cummings-Paul Hamiltonian. By solving Heisenberg equations in Fourier space and describing electric field by a generalized-transverse Green function, we obtain spectral density for a quantum dot which is in the strong coupling to a slab photonic crystal cavity. Afterward, by solving Shrouding equations precisely we demonstrate when quantum dot is in a very strong coupling to cavity, rotate wave approximation is not reliable anymore. It means that if coupling constant gets comparable to cavity mode frequency then the prevalent approach to solve this Hamiltonian will not be correct....

Analysis of Ultra-Strong Coupling in Optical Waveguides

, M.Sc. Thesis Sharif University of Technology Karimi, Farhad (Author) ; Khorasani, Sina (Supervisor)

Abstract

In this project, we were intended to study the ultra-strong coupling in optical waveguides. Hence, we analyze the interaction of an electromagnetic wave with a quantum well embedded in a dielectric slab waveguide. First, we designed a QW with and alloys, which the energy of its electron-heavy holes transition is . By exploiting the envelope function approximation, we derived the wavefunction of electrons and holes, their eigen-energies, and the dipole moment of electon-holes. For finding the wavefunction of holes and their eigen-energies, we used the Luttinger Hamiltonian. Next, we calculated the electrical susceptibility of a three level quantum system (as a model for QW), by using...

Cavity Quantum Electro-Dynamics in Ultra-Strong Coupling Regime

, M.Sc. Thesis Sharif University of Technology Arab, Abbas (Author) ; Khorasani, Sina (Supervisor)

Abstract

Cavity Quantum Electro-Dynamics (CQED) in Weak, Strong and Ultra-Strong coupling Regimes are studied. A MATLAB m-file is written which is able to solve any arbitrary CQED configuration. This program demands input data such as number of Quantum Dots, number of energy levels of each Quantum Dot, energies of each energy level of Quantum Dots, Number of cavity modes, eign-frequency of each cavity mode, coupling constant, dipole strength of each allowed transition of Quantum Dots and initial state of system from user and begins to solve the Schrodinger equation for annihilation and atomic ladder operators. In addition, coefficients of each possible ket will be calculated. Since, any approximation...

Nonlinear Torsional Vibrations of Thin Walled Beam with Semi-Analytic Methods

, Ph.D. Dissertation Sharif University of Technology Sina, Ali (Author) ; Haddadpour, Hassan (Supervisor)

Abstract

Thin Walled Beams are widely used in engineering applications with the minimum weight design criteria, ranging from civil to aerospace and many other industrial fields. The weight reduction of the beam leads to importance of the dynamic behavior of the structure. Frequently used thin walled beams have low torsional stiffness and their torsional deformations may be of such magnitudes that it is not adequate to treat the angles of cross section rotation as small. When the vibration amplitudes are moderate or large, the geometric nonlinearity must be included and some new phenomena which do not exist in linear torsional dynamic come into play. Unfortunately, the equations of motion of nonlinear...

Design and Analysis of Delay Lines Based on Photonic Crystal Coupled Cavities

, M.Sc. Thesis Sharif University of Technology Bayat, Mina (Author) ; Khorasani, Sina (Supervisor)

Abstract

In the recent years, photonic crystal (PhC) devices vastly have been paid attention due to their ignorable loss, very low group velocity, flexibility in shape and dimension.In this thesis a PhC coupled cavity ring known as superresonator is introduced and its properties and applications is studied. Also modes of the structure are extracted through both coupled-resonator model and FDTD method, and two of its application is described and studied. Add-drop filter is one of the essential devices in WDM systems. First, an application of superresonator in designing add-drop filters is explained and a novel filter based on the superresonator is introduced and analyzed by FDTD and coupled mode...

Axial-torsional vibrations of rotating pretwisted thin walled composite beams

, Article International Journal of Mechanical Sciences ; Vol. 80 , 2014 , pp. 93-101 ; ISSN: 00207403 Sina, S. A ; Haddadpour, H ; Sharif University of Technology

2014

Abstract

Axial-torsional vibrations of rotating pretwisted thin-walled composite box beams exhibiting primary and secondary warping are investigated. Considering the nonlinear strain-displacement relations, the coupled nonlinear axial-torsional equations of motion are derived using Hamilton's principle. Ignoring the axial inertia term leads to differential equation of motion in terms of elastic torsion in the case of axially immovable beams. Centrifugal load in the presence of material anisotropy and pretwist angle leads to an induced static torque. The nonlinear equation should be linearized about the corresponding equilibrium state to obtain the linear differential equation of motion. Extended...

Comment on "vibration of turbomachinery rotating blades made-up of functionally graded materials and operating in a high temperature field" by S-Y. Oh, L. Librescu and O. Song (Acta Mech. 166, 69-87, 2003)

, Article Acta Mechanica ; Volume 218, Issue 3-4 , 2011 , Pages 375-376 ; 00015970 (ISSN) Sina, S. A ; Haddadpour, H ; Sharif University of Technology

2011

Response to the Authors' reply to the Comment on "vibration of turbomachinery rotating blades made-up of functionally graded materials and operating in a high temperature field", doi:10.1007/s00707-010-0407-5

, Article Acta Mechanica ; Volume 218, Issue 3-4 , 2011 , Pages 379-382 ; 00015970 (ISSN) Sina, S. A ; Haddadpour, H ; Sharif University of Technology

2011

Successive concave sparsity approximation for compressed sensing

, Article IEEE Transactions on Signal Processing ; Volume 64, Issue 21 , 2016 , Pages 5657-5671 ; 1053587X (ISSN) Malek Mohammadi, M ; Koochakzadeh, A ; Babaie Zadeh, M ; Jansson, M ; Rojas, C. R ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2016

Abstract

In this paper, based on a successively accuracy-increasing approximation of the ℓ0 norm, we propose a new algorithm for recovery of sparse vectors from underdetermined measurements. The approximations are realized with a certain class of concave functions that aggressively induce sparsity and their closeness to the ℓ0 norm can be controlled. We prove that the series of the approximations asymptotically coincides with the ℓ1 and ℓ0 norms when the approximation accuracy changes from the worst fitting to the best fitting. When measurements are noise-free, an optimization scheme is proposed that leads to a number of weighted ℓ1 minimization programs, whereas, in the presence of noise, we propose...

Optimization of Actuators Position of a Low Aspect Ratio Variable-camber Wing and Derivation of Its Aerodynamic

, M.Sc. Thesis Sharif University of Technology Mohammadi Zadeh, Sina (Author) ; Dehghani Firouzabadi, Rouhollah (Supervisor) ; Haddadpour, Hassan (Supervisor)

Abstract

Morphing concepts can potentially improve the performance and fuel consumption of modern aircrafts. Smart materials can reduce the weight and complexity, and also are of the best choices to improve efficiency and reliability for realizing morphing wings. Developing of a simple model and optimization of smart piezocomposite actuators position of a thin wing with variable camber is considered. The goal is to gain desired properties in incompressible subsonic regime. Lifting surfaces of a composite wing are simplified using shell model. Keeping the problem simple, a piezocomposite patch is used to change the shell curvature. Basic modes are extracted from FEM software and behavior of bimorph...

Effects of resistive loads and tire inflation pressure on tire power losses and CO2 emissions in real-world conditions

, Article Applied Energy ; 2015 ; ISSN: 03062619 Sina, N ; Nasiri, S ; Karkhaneh, V ; Sharif University of Technology

2015

Abstract

Considerable portion of energy losses in a vehicle traced to tire. Energy losses in a tire are due to tire longitudinal slip as well as rolling resistance. Hence, both of aforementioned factors must take into the consideration to study the tire energy loss. Present paper aims to investigate the power losses in tires and to examine influence of road conditions and tire inflation pressure on them. To cover the real-world conditions, experiments were done on a gasoline-fueled passenger vehicle on an urban highway along two routes with same length and opposite gradients to comprise the change of road conditions. Then, by use of engine performance model which is prepared in dynamometer...

Effects of resistive loads and tire inflation pressure on tire power losses and CO2 emissions in real-world conditions

, Article Applied Energy ; Volume 157 , November , 2015 , Pages 974-983 ; 03062619 (ISSN) Sina, N ; Nasiri, S ; Karkhaneh, V ; Sharif University of Technology

Elsevier Ltd 2015

Abstract

Considerable portion of energy losses in a vehicle traced to tire. Energy losses in a tire are due to tire longitudinal slip as well as rolling resistance. Hence, both of aforementioned factors must take into the consideration to study the tire energy loss. Present paper aims to investigate the power losses in tires and to examine influence of road conditions and tire inflation pressure on them. To cover the real-world conditions, experiments were done on a gasoline-fueled passenger vehicle on an urban highway along two routes with same length and opposite gradients to comprise the change of road conditions. Then, by use of engine performance model which is prepared in dynamometer...

Explicit degradation modelling in optimal lead-acid battery use for photovoltaic systems

, Article IET Generation, Transmission and Distribution ; Volume 10, Issue 4 , 2016 , Pages 1098-1106 ; 17518687 (ISSN) Sina Hamedi, A ; Rajabi Ghahnavieh, A ; Sharif University of Technology

Institution of Engineering and Technology 2016

Abstract

Lead-acid battery is a storage technology that is widely used in photovoltaic (PV) systems. Battery charging and discharging profiles have a direct impact on the battery degradation and battery loss of life. This study presents a new 2-model iterative approach for explicit modelling of battery degradation in the optimal operation of PV systems. The proposed approach consists of two models: namely, economic model and degradation model which are solved iteratively to reach the optimal solution. The economic model is a linear programming optimisation problem that calculates the optimal hourly battery use profile based on an assumed value of the battery degradation cost. The degradation model,...

Behavior Patterns Analysis of Cavity Quantum Electro-Dynamics in Complex Systems for Different Coupling Regimes

, M.Sc. Thesis Sharif University of Technology Alidoosty Shahraki, Moslem (Author) ; Khorasani, Sina (Supervisor)

Abstract

In this M.Sc. thesis the behavior patterns of the cavity quantum electrodynamics of complex systems are analyzed, such systems are quantum optic multi-partite systems and consist of an arbitrary number of quantum dots in interaction with arbitrary number of cavity modes.
First, the coefficients matrix of the ket sate of the system was measured, in order to achieve it; the general time-dependent state of the most general possible system was specified. Its related Hamiltonian was written, and finally the Schrodinger equation was measured in different coupling regimes. It was done in Schrodinger picture without any approximation.Second, the presence probabilities of the quantum dots of any...