Sharif Digital Repository

Here, we first ivestigate some available nonsmooth algorithms indentilying their drawbacks, and then provide some guidelines to avert these drawbacks. We divide the algorithms to two main classes, first order and second order. The main drawback of the second order class of algorithm is that there does not exist any suitable method to approximate the generalized second order derivative. To solve this problem, we construct a uniform approximation for the generalized Hessian matrix of an SC1 function. Using the discrete gradient and the extended second order derivative, we define the discrete Hessian matrix. We construct a sequence of sets, where each set is composed of discrete Hessian... 

In recent years, UWB multiple access communication systems have received a great attention due to its many advantages. The most important advantages of a UWB system can be summarized as its high data rates, low power consumption, fading immunity and high precision routing. One of the important problems in a UWB system implementation is in its receiver part in which in order to use a coherent RAKE receiver, the channel coefficients have to be estimated. Since UWB channel is a dense multipath fading channel with a very high number of resolvable paths, the channel coefficient estimation based on using training sequence is very complicated. To resolve this problem, transmit reference (TR)... 

Goal of this project is to present a method for dynamic transmission planning in restructured environment by system regulator. Congestion, fair competition in power market, stakeholders’ desires in transmission expansion, transmission investment traits, creating incentive for investment and transcos revenue are considered in this work. Presentation of methodology for reliability evaluation is necessary because of increasing uncertainties due to restructuring. Remedial action method is suggested for uncertainties analysis and reliability index presented for measuring degree of reliability. The method has been applied to the IEEE 14-bus system. ... 

The development of an oil field plays an important role in the optimum production. In the past, several wells have been used in a multi layer reservoir to produce oil from each layer. It costs oil industry billions of dollars and the problem would be more severe in the offshore. Nowadays, one well can produce oil from different pay zones in a reservoir. In this type of well called smart or intelligent well, production tubing is in common between pay zones and some chokes are installed on the tubing to produce oil from different layers. The size of choke usually varies and can be controlled by an electrical system installed in the well. As each pay interval has different capacity in terms of... 

Using cryptographic hardware device is inevitable these days. Hence, the secret information inside these devices should be safe and non-attackable. Simple and differential Power analysis (SPA, DPA), a form of side channel attack, allows attacker to study circuit information leakage by analyzing and monitoring power consumption of a cryptographic hardware device to extract inside information and discovering the secret keys. In this thesis, first, a sample cryptographic hardware device is designed and implemented as an under attack system. Then, another device is designed as an attacker in order to attack the mention sample hardware by analyzing and monitoring its power consumption. A digital... 

Ring and disk resonator are studied in this thesis. First, the complex resonance frequencies of two-dimensional homogeneous ring and disk resonators are extracted by following the standard approach and then a novel method is proposed to extract the complex eigen-frequencies of two-dimensional inhomogeneous ring and disk resonators. The inhomogeneity of the refractive index is arbitrary along the radial direction. The proposed method is shown to be more efficient than the standard approach based on the stair-case approximation. It is therefore appropriate for resonator design and is thus employed for systematic study of the opposing trends of geometrical parameters in maximization of... 

This dissertation is a survey on linear and nonlinear dynamics of single-walled carbon nanotubes (SWNTs) conveying fluid with different boundary conditions. A detailed review on Some of the most important studies on free vibration and instability of CNTs conveying fluid is done. By employing the nonlocal continuum field theory of Eringen and Von Karman nonlinear strains, an analytical model are developed. In linear analysis the natural frequencies and critical flow velocities are discussed. In nonlinear analysis effect of nonlocal parameter on Nonlinear dynamics of cantilevered SWNTs conveying fluid investigated by bifurcation diagram, phase plane and Poincare map. The numerical results... 

Today’s technological trend towards higher performance microwave and digital circuits at increasingly smaller sizes poses new challenges to both the microwave and high-speed VLSI designers. One aspect of these challenges lies in the fact that nonuniform transmission structures must often be used to reduce circuit sizes, to increase circuit bandwidth, to reduce discontinuity effects, and to optimize the overall circuit performance. Coupled microwave transmition lines are one of most common microwave circuits, that are use to design couplers, power dividers, hybrids, baluns, filters, phase shifters, matching circuts and so on. The broadband tight couplers are one of interesting devices that... 

In this thesis, we introduce and prove the inequalities and theorems of Smulian which are about derivatives of convex functions and optimization of linear functionals. Then we show that some old ideas of Smulian can be used to give another proof of theorems of Bourgain. The first theorem of Bourgain associates to any bounded, convex, closed and dentable subset like D of a Banach space X a G-delta subset of the dual space and the second theorem of Bourgain investigates the optimization in Banach spaces. Finally, we characterize subsets of Banach spaces having the Radon-Nikodym property by means of optimization results.
 

This project introduces a topology enabling a Low-Noise Amplifier (LNA) not only to attenuate the unwanted signals at the input stage but also to satisfy the input matching requirement in an ultra wide frequency band. Moreover, a single ended to differential signal conversion method is proposed. This method employs a noise reduction idea, so it has a lower noise figure compared to the other introduced methods with the same purpose. The introduced methods have been utilized in designing two 0.18μm reconfigurable CMOS LNAs. One of the designed LNAs covers 2.3-3.6 GHz band width and the other one covers the UHF (470-860MHz) band. Stringent sensitivity requirement, presence of strong in-band... 

Major bone defects resulted from diseases or hurts that can not heal naturally, requaire bone transplantation. golden standard for transplantation is autologus one but it has some disad-vantages such as economic burden, the lack of graft source, surgery on patient, and so on. so exploring altrnative ways led to exploit stem cells.traditionally bone marrow mesenchymal stem cells (MSCs) used for stem cell-bsaed bone regeneration. bone marrow aspiration to aquaire stem cells is painfull and give a population of cells such as hematopoetic cells that requaire to seperate and can not be handled in first passages. MSCs can be substituted by multipotent adipose tissue-derived stem cells (ADSCs) in... 

In this thesis, first we will have a brief review on hash functions and related concepts.Then, we will descibe the hash function, Cubehash, which is one of the competitors in the competition held by NIST for selecting SHA-3 standard. Next, we will describe an attack based on linearization of differential paths in hash functions and apply this attack on Cubehash. At the end, we will discuss the results of this attack on Cubehash  

Given a principal bundle a characteristic class is an element of the cohomology al- gebra of the classifying space of structure group of the bundle with coefficients in a commutative ring with unit ,which have a functorial property .When the structure groupe of the bundle is a Lie group and the coefficient ring is the real or complex num- bers , the Chern–Weil approach provides a geometric construction of char-acteristic classes. Classical Chern–Weil formalism relates geometry to topology, assigning to the cur- vature of a connection, de Rham cohomology classes of the underlying manifold.This theory developped in the 40’s by Shiing-ShenChern and Andre Weil which can be seen as a generalisation... 

In RFIDtags application or sensor network for some hardware constraints we can not use all-purpose crypto systems such as AES,DES.In this applications in trade off between security and efficiency considering inherent limitation،we desire to satisfy moderate level of security.In recent years various lightweight algorithm has been designed.Purpose of this thesis is cryptanalysis on MIBS as a lightweight algorithm.This lightweight block cipher with Feistel structure and data length of 64-bit uses key lengths of 64-bit or 80-bit and consists of 32 rounds.Methods of attacks are differential،impossible differential and differential fault.the results of differential and impossible differential... 

In this work we investigate the propagattion of light in inhomogenous cosmic spacetime within general relativity framework. We use Lemaitr-Tolaman-Bondi metric for modeling inhomogenous spacetime. For investigation of gravitational lensing we need to solve geodesic equaions in this model. Beacuse of nonlinearity and complexity of these equations we should apply numerical methods. At first we used Runge-Kutta method with adaptive step size, but beacuse of stiffness of these equaions, the results of this method did not match to approximation methods for low deflection angles. So we try semi-implicit Rosenbrock method. Then for inspection of thin lens approximation for the first time; we... 

n this thesis we have investigated stochastic evolution equations by variational method. For these equations, explicit and implicit numerical schemes are presented. We have performed these numerical schemes for stochastic heat equation. We have investigated 2-D Navier-Stokes equation too  

On the contrary to common explanations of fertility transition in the Iraninan Economy there has been a growing human capital without decline of fertility for some decades followed by a rapid fall in fertility without a higher growth of human capital during the next decades. Accounting for these facts we propose a new link between subsidies financed by exogenous oil revenue and the evolution of fertility and human capital. While the educational subsidy accelerates the growth of human capital, the presence of financial subsidies keeps fertility from declining. Then, fertility declines with sizeable delay but sharply because (i) high fertility in first generations implies a growth rate of... 

In this thesis, we consider an implicit approximation scheme for the stochastic heat equation with additive and multiplicative space-time white noise. we use the spectral Galerkin method in space combined with the linear implicit Euler method in time to simulate weak approximation error  

Semilinear stochastic evolution equations with multiplicative Lévy noise and monotone nonlinear drift are considered. A novel method of proof for establishing existence and uniqueness of the mild solution is proposed. We also prove the continuous dependence of the mild solution with respect to initial conditions and also on coefficients. As corollaries of the continuity result, we derive sufficient conditions for asymptotic stability of the solutions, we show that Yosida approximations converge to the solution and we prove that solutions have Markov property. Examples on stochastic partial differential equations and stochastic delay differential equations are provided to demonstrate the... 

Streamline Curvature method is one of the most commonly used methods by industry for prediction of axial flow compressors. This method analyze axial compressor by solving radial equations in the meridional plane to locate streamlines and also by using empirical models to predict total pressure loss. Despite growth of CFD models, Streamline Curvature method has been considered as most practical method for compressor preliminary design and performance assessment because of it’s high speed and good precision. In the current work a C++ code (SLC) has been developed using streamline curvature for axial flow compressor performance analysis. This code receives compressor geometry, properties of...