Sharif Digital Repository

Channel estimation is one of the fundamental challenges in every communication system and different algorithms have been proposed to deal with it. Obviously, type of a communication channel is an important factor in choosing the appropriate method for channel estimation. Sparse channels are one kind of them that occur in many real-world applications such as wireless communication systems. In addition, emergence of a new means in signal processing to deal with sparse signals, known as Compressed Sensing(CS), paved the way for their extensive usage in many applications including sparse channel estimation.On the other hand, one of the most fundamental problems in sparse signal recovery using CS... 

This study explores the trajectory optimization of two aircrafts’ formation flight seeking minimization of fuel consumption and flight duration while considering activation of the Traffic Collision Avoidance System (TCAS) during the flights. In order to model the effects of this system, a set of codes has been developed in the Matlab software environment, which utilizes an estimation model of induced drag for each aircraft by their relative positions. Also, position rotation is allowed, and the number and location of rotations are controllable by the user. The TCAS determines the allowable distances between aircrafts during flights based on relative velocities and relative heading angles.... 

The objective of this research is to design an adaptive controller for a class of fractional-order nonlinear systems in the strict-feedback form with unmodeled dynamics. Actuator saturation and actuator fault are also considered. All of the system states are assumed to be measurable, and all the sensors can be faulty. Fractional-order systems are chosen because, in the modeling of physical systems, the fractional-order calculus is often preferable to the classical integer-order calculus. The controller is designed by using the backstepping design technique. The fuzzy logic systems are used to eliminate the problem of "explosion of complexity" in the conventional backstepping method and also... 

Flow control means changing the optimal flow behavior of the fluid in accordance with the desired targets, such as decreasing drag force, increasing the lift force or lift to drag ration, as well as manipulating the separation of the flow from the surface. So far, little research has been done on increasing the airflow performance through the active control of the trailing edge flow. Gurney flap is a great tool, and its experimental results show a significant increase lift force in the airfoil. In this study, it is possible experimentally to use plasma actuators to create microtap and garney flap artificial for enhancing the aerodynamic performance of airfoil by controlling the flow field at... 

One of the features of a project is its uniqueness, if two sets of activities are the same neither of them will longer be included in the project definition. A method in two projects with the same nature may yield inverse results of each other. Therefore, it is necessary to study the parameters affecting the project carefully before any action. So far, some research has been conducted in this area and it has been tried to perform case study on qualitative and quantitative parameters of the project. By investigating a number of common factors in most civil engineering projects, especially megaprojects, the present study attempts to identify and examine exquisite and effective parameters and... 

In this study, based on Households Income and Expenditure Survey (HIES) data, we examined the socio-economic characteristics and transition of Iranian urban households in each of the three different income groups from 1997 to 2020. Moreover, factors affecting entry to poverty or persistence in poverty in Iranian urban households are discussed.The results of this study show that, contrary to popular belief, there is no evidence of accumulation of entrepreneurs and business owners in the urban middle class. Rather, middle-income households have higher-skilled jobs and pay more for social security than low-income ones, as well as pay more attention to investing in human capitals (education and... 

Wastewater, especially with heavy metal contamination, is a global environmental concern. Numerous techniques have been tested for online controlling and monitoring the concentration of heavy metal ions; yet, there are many challenges in performing these techniques. Biosensor is cheap, easily available, simple, fast, selective, sensitive, and repeatable so it is an excellent alternative for the detection and quantification of hazardous particles in the wastewater. In this study, a Nano biosensor with high detection of copper ions has been fabricated. PEDOT:PSS as a highly conductive polymer is coupled with gold nanoparticles to modify the surface of graphite electrode and results in higher... 

Nanophotocatalysts containing metal oxides and oxy-acids based on the nanoporous materials such as graphene, metal-organic-frameworks and carbon nano tubes were synthesized. The photocatalytic properties of the prepared samples were evaluated by the photodegradation of different pollutants in the suspension and emulsion photocatalytic systems. This study demonstrates a new kind of photocatalytic system via utilization of the superior specific properties inherent in Pickering emulsion. We designed the new photocatalytic system using a photocatalytic active component and hydrophobic conducting nanostructures to form the stabilized Pickering emulsion (Pe-bp system). The results revealed that...