Sharif Digital Repository

The main topic of this research is the navigation and control of a free-flying satellite with a robot manipulator while transferring and placing cargo on a space station. After connecting the cargo module, astronauts and robots need to deliver the available loads to the desired modules in a space station. Capturing an object or cargo is a critical issue studied extensively so far. However, delivery and placing of the cargo at the target point have not been investigated yet, to the best of the author’s knowledge; hence, this is a primary motivation for conducting the proposed research. After capturing the payload, the position and attitude of the manipulator with respect to the station’s... 

Export subsidy is one of the important issues among the various trade policies in developing countries. For more than a century, various effects of export subsidies have been studied in literature and different results have been presented. In this study, the effect of export subsidy of several agricultural products on their weight and export price has been investigated. In 2015 and 2016, respectively, potatoes and five groups of dairy products were subject to cash subsidies. The results of the research show that the growth of potato’s weight has been affected by the subsidy and has increased. Also, according to the results, the effects of the decrease in export price growth can be seen, and... 

Persistent homology is one of the main tools in Topological Data Analysis. Indeed, to deal with a huge dataset while noise sensitivity is important, persistent homology can reflect some information about data in the form of persistent homology groups and persistence diagrams. Note that statistical or linear algebraic tools are not suitable to work with huge datasets with very high dimensions. In this thesis, we discuss the concept of persistent homology and investigate some of its properties such as the stability of the persistence diagrams. Indeed, persistence diagrams are obtained from the generating sets of the persistent homology groups. Further, we discuss an application of persistent... 

Ion sources have changed significantly since ion implantation was first used commercially. High beam current and good performance with long lifetime are the keys in an ion source. Freeman ion sources are facing challenges such as the short lifetime of the filament, the single charge of the extracted ions. In the third chapter, these challenges and solutions for them are described. In this thesis, while examining different types of ion sources and comparing them with the combination and simulation of Freeman Varian 300XP ion source performance, an improved Freeman ion source is also presented. Also, the results obtained through simulation using Comsol 6.1 software and MATLAB program have been... 

The development of the boundary layer and shock boundary layer interaction essentialy determine the performance boundaries of transonic aircrafts. Employing shock and boundary layer control has therefore a large potential for improving flight performance. Aerodynamic surfaces of these aircrafts usually have very closed design points and critical points so small changes in angle of attack and free stream mach number cause entering drag divergence. Adaptive wings are the aerodynamic surfaces that use additional devices to control the flow pattern for improvment of aerodynamic performance in different flight conditions. Shock Control Bump is a control mechanism that is used for shock wave...