Sharif Digital Repository

In this research, the design of control system has been studied for a special flying vehicle at whole of flight time. This flying vehicle is vertically launched and few time after launch its attitude changes to the desired attitude by a reaction jet control system, then the acceleration commands are tracked when the aerodynamic is activated. Design process includes attitude control system design in launch phase and aerodynamic control system design. Because of the existence of nonlinear and multi-variable dynamics in the flying vehicle and the presence of uncertainty and disturbance, combination of nonlinear, robust and adaptive methods are used in controller design process. Design of... 

Quantum correlations are among most intriguing problems in physics. Bell’s inequality which was proved in 1964 provides with us the possibility of comparing the predictions of quantum theory with what an underlying local realistic theory may reproduce for some given observables in correlated states. The violation of Bell’s inequality in practice prohibits the existance of such underlying theories. Yet, it is not clear which of the assumption, i.e., locality or reality is responsible for explaining the experimentally verified violations. In 2003, a Nobel prizewinner A. J. Leggett proved a new inequality in which the locality assumption was not crucial. Here, we explore different aspects of... 

Parkinson's disease is a destructive and long-term disease of the central nervous system. This disease especially affects the motor system. Parkinson's patients can be studied under dopaminergic and non-dopaminergic conditions. The non-dopaminergic state means not taking the drug, for at least 12 hours, and the dopaminergic state, from one hour to less than 12 hours after taking the usual dose of the dopaminergic drug. The aim of this study is to examine and compare the statistics and characteristics of Parkinson's patients in dopaminergic and non-dopaminergic states, focusing on reaching and tracking activities. It also aims to analyze the differences before and after rehabilitation in... 

Let G be a graph with adjacency matrix A and Δ be a diagonal matrix whose diagonal entries are the degree sequence of G. Then the matrices L = Δ− A and Q = Δ+A are called Laplacian matrix and signless Laplacian matrix of G, respectively. The eigenvalues of A, L, and Q are arranged decreasingly and denoted by λ1 ≥ · · · ≥ λn, μ1 ≥ · · · ≥ μn ≥ 0, and q1 ≥ · · · ≥ qn ≥ 0, respectively. The energy of a graph G is defined as E(G) :=
n
i=1
|λi|.
Furthermore, the incidence energy, the signed incidence energy, and the H¨uckel energy of G are
defined as
IE(G) :=
n
i=1
√
qi, LE(G) :=
n
i=1
√
μi, HE(G) :=

2
r
i=1 λi, n=... 

A traffic classifier maps each input stream into a pre-defined traffic class. If the traffic is encrypted using a protocol, such as SSL, or is protected using an encrypted tunnel, it's content would be hidden from the classifier, in which case the common traffic classification methods will be ineffective. Although common security mechanisms which provide information confidentiality to user can't hide all properties of messages, including length and time. Some of the newly presented methods of traffic classification utilize these properties and can actually classify messages without accessing their content. We will study such methods and their limitations in this thesis. Of all the encrypted... 

Scale formation is an unpleasant phenomenon that occurs when the mixed fluids are incompatible. The scales damage the reservoir, wellbore and the surface facilities. They reduce the effective fluid path and increase the pressure drop of the system; so it is necessary to study the precipitation thermodynamics of scale formation, and present a trustable method for banning the scales from precipitation. In this project, it has been tried to study the value of precipitated scale due to the mixing of two incompatible waters (Civand and Sea Water). The results of which are compared with the results of a geochemical software named PHREEQC. Then, the performance of hydro chloridric acid as a scale... 

Drilling Operations constitute more than fifty percent of total costs of well construction operations. Due to this fact, optimization of drilling operations could have significant effect on decrease in total costs of well construction. It is mentioning worthy that there are a variety of parameters which affect drilling operations from the view point of optimization. In many cases several of those aforementioned parameters are contrary in nature. Thus obtaining an integrated approach to optimize the operation by considering these effects is necessity. The goal of this thesis is to investigate different influential parameters of drilling operation optimization and to develop computer-based... 

We report on numerical and intelligent modeling of three-dimensional laminar flow of non-Newtonian fluids driven by axial pressure gradient in annular media consisting of a coaxially rotating inner cylinder. This is an example of a rotating Couette flow with vast applications in food, oil and gas, and chemical engineering industries. We study the dynamics of pressure in and the velocities (in three directions X, Y and Z) of every grid in presence of rotation and without that by means of CFD. Afterward, we develop a novel predictive model based on an Artificial Neural Network (ANN). The hybrid ANN framework is trained and tested by over 100000 data which collected by CFD. We then perform... 

Graph Labeling is one of the most active initiatives in graph theory which was introduced in the early 1960’s. One of the most prominent kind of labeling in literature is magic-type labeling inspired by defining magic numbers and magic squares. It also encompasses various types. Total edge magic labeling of Graph G, is a bijection f from V(G)∪E(G) on the set of {1,2,…,|V(G) |+|E(G) |}, on this condition that the summation of each edge label and its vertices’ labels is constant for all edges. Since introducing total edge magic labeling, numerous researches is done that mostly are dedicated to prove mathematical theorems and depicting a whether a distinct graph is magic or not. Therefore, it... 

Using free laccase, enzymatic decolorization of two azo dyes were optimized. The optimum conditions with the aim of maximizing the decolorization of AB92 dye (92.30%) were: dye concentration = 11.85 mg L-1, pH = 5.1, and enzyme concentration = 98.37 mg L-1. While, these conditions to achieve the maximum decolorization yield of DR23 (95.60%) were: dye concentration = 17.68 mg L-1, pH 3.7 and enzyme concentration =97.89 mg L-1.In the second part, the laccase enzyme was covalently immobilized onto GO nanosheets. At the concentration of graphene oxide and laccase enzyme equal to 1 mg mL-1 and 0.9 mg mL-1, respectively, the enzyme loading was 156.5 mg g-1 and the immobilization efficiency was... 

In recent years, unmanned vehicles have intensively been developed to reduce human dangers for marine applications. Predicting the hydrodynamic coefficients of an autonomous underwater vehicle is important during the vehicle’s design phase. In other words to design an AUV, one must clarify its maneuverability and controllability based on a mathematical model. The mathematical model contains various hydrodynamic forces and moments expressed collectively in terms of hydrodynamic coefficients. Therefore, the correct values of the coefficients must be known to precisely design the controller of AUVs.SUT-2 is an AUV, being developed by Marine Engineering Laboratory of Sharif University of... 

Most of the current application and potential FGM included in the areas related to contact mechanic .These issues essentially are related to the transfer of force between two objects, that in general is with friction, so in this study the contact under the loading of horizontal and vertical with its different aspect such as the effect of contact region, the effect of round and also the effect of getting harden and soften of FGM.
The used method is a numerical method ¬(finite element method) that will resulted in contact equation discretisce by use of Penalty method. In this thesis is also presented the needed algorithms for solving the problem and the finite element code for solving the... 

In this thesis failure analysis of a critical part in a landing gear of a commercial aircraft was conducted.Fatigue phenomenon was determined as the reason for the failure and fracture of the mentionedcomponent. Fractography investigation of the fracture surface and charasteristicswas conducted.Scanning Electron Microscope was utilized for the study of the fracture surface. In the fracture surface, fatigue striations were observed. An experimental model of the crack growth is presented by using the fracture surface characteristics. By counting the fatigue striations and measuring their distance betwwn them on the fracture surface, the rate of the crack growth and crack growth life were... 

The reliability of integrated circuits (IC) is related to material imperfections such as holes, cavities, cracks and etc. which occur in the manufacturing process. The operational conditions of IC create thermal stresses. These thermal stresses increase the chance of failure by making the imperfections critical in IC’s components such as VIA that is used as connection between interconnects in the multilevel integrated circuits. As a result, thermal fatigue needs to be investigated in VIA thoroughly.
The thermal stresses in VIA increase the possibility of hole forming due to hydrostatic stresses during manufacturing process and the amplitude of applied stresses under the operational... 

Nowadays, the use of finite element Software applications in enigineering departments has become Inevitable and commonplace. Acceptance of the necessity of using such software applications for reducing the cost of research and development does not require any evidences of financial instruments to be presented. Reducing design and manufacture time together with pseudo-empirical approach has cuased the finite element science to become a conventional designing tools.
Since contact is the main method to apply a load on a ductile object,and stress concentration caused thereby is often a major cause of failure in mechanical parts, the issue of contact is a fundamental topic in mechanics of... 

In this project, the structure of an aircraft and its sensitive areas has been studied for fatigue damages and then the design philosophies have been analyzed. Subsequently, relevant analysis and calculations have been conducted on a critically important part of the airframe (due to its location), which has suffered fatigue due to the age of the aircraft. This part belongs to the airframe of a Boeing 747, known as frame 360 in section 41 of the body of the aircraft, in which the numerous flight cycles have led to the creation and propagation of fatigue crack.
In the first stage of this project, the remaining life time of the frame has been estimated using theoretical relationships. In... 

In this dissertation, we introduced a Fuzzy based representation and comparison method for sequential patterns such as speech and online handwriting. The new model, called Fuzzy Elastic Matching Machine (FEMM), is simpler than traditional HMM based approaches and is not based on the common statistical assumptions of HMM systems. The model was tested on isolated word and phoneme recognition tasks in speech recognition domain and isolated letter recognition in Persian handwriting recognition. We showed that this method is faster than traditional HMM based models and more robust to noise. To train the model, we introduced a Symbiogenesis-based evolutionary training algorithm. This algorithm...