Investigating Different Crumb Rubber Modification Methods in Cold Mix Asphalts

, M.Sc. Thesis Sharif University of Technology Daneshvar, Dana (Author) ; Motamed, Arash (Supervisor)

Abstract

Studies have shown that use of crumb rubber additive can improve the mechanical and performance properties of hot mix asphalts. Nowadays, different methods are used for adding crumb rubber to asphalt mixtures. However, no comprehensive research has been done to investigate the effects of these different methods in cold mix asphalts. In this research, different crumb rubber modification methods were evaluated to compare their effects on cold mix asphalts’ performance. In this regard, various crumb rubber modification methods, such as pre blending crumb rubber into the asphalt before emulsification, post blending crumb rubber into the prepared asphalt emulsion and blending crumb rubber with...

Improving fracture and moisture resistance of cold mix asphalt (CMA) using crumb rubber and cement

, Article Road Materials and Pavement Design ; 2020 Daneshvar, D ; Motamed, A ; Imaninasab, R ; Sharif University of Technology

Taylor and Francis Ltd 2020

Abstract

Due to environmental and economic advantages, cold mix asphalt (CMA) can be considered as a good alternative to conventional hot mix asphalt (HMA). Nevertheless, it has inferior performance compared to HMA, so that the application of CMA is not recommended in the surface layer of pavements subjected to high traffic volume and/or regions with very cold or hot climate. Considering the high potential of distress occurring in the CMAs, this research is aimed at investigating the effect of crumb rubber (CR) on fracture and moisture damage resistance of the CMAs. Different CR percentages were applied through two different modification methods and, then by means of Semi-Circular Bending (SCB) test,...

Improving fracture and moisture resistance of cold mix asphalt (CMA) using crumb rubber and cement

, Article Road Materials and Pavement Design ; Volume 23, Issue 3 , 2022 , Pages 527-545 ; 14680629 (ISSN) Daneshvar, D ; Motamed, A ; Imaninasab, R ; Sharif University of Technology

Taylor and Francis Ltd 2022

Abstract

Due to environmental and economic advantages, cold mix asphalt (CMA) can be considered as a good alternative to conventional hot mix asphalt (HMA). Nevertheless, it has inferior performance compared to HMA, so that the application of CMA is not recommended in the surface layer of pavements subjected to high traffic volume and/or regions with very cold or hot climate. Considering the high potential of distress occurring in the CMAs, this research is aimed at investigating the effect of crumb rubber (CR) on fracture and moisture damage resistance of the CMAs. Different CR percentages were applied through two different modification methods and, then by means of Semi-Circular Bending (SCB) test,...

, M.Sc. Thesis Sharif University of Technology Daneshvar, Mohammad (Author) ; Zohuri Zangeneh, Bijan (Supervisor)

Abstract

Theoretical investigation of stochastic delay differential equation driven by fractional Brownian motion is important issue because of its application in the modeling. In this thesis, after defining of the stochastic integral with respect to fractional Brownian motion and describing the delay differential equation, we prove existence and
uniqueness of solution of stochastic delay differential equation driven by fractional Brownian motion with Hurst parameter H>1/2 and we show that the solution has finite moments from each order. Moreover we show when the delay goes to zero, thesolutions to these equations converge, almost surely and in Lp, to the solution for the equation without delay....

Robust Control of Satellites Formation Flying

, M.Sc. Thesis Sharif University of Technology Hassani, Ali (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

Recent developments in space industry and the great tendency for definition of efficient, precise and low cost missions are the main reasons for the growing interest in satellites formation flight. Regarding the aforementioned, the study of the multiple satellite control methods is the subject of the present project. In this project, the governing equations of motion of satellite formation flight are developed. Based on this development, it is shown that the satellite linear equations of motion like many other linear system presentations, can not sufficiently model the real system. Therefore, some of the most famous uncertainties in space dynamics such as semimajor axis and eccentricity...

Development of a Distributed Algorithm for Flocking of Non-Holonomic Aerial Agents

, M.Sc. Thesis Sharif University of Technology Soleymani, Touraj (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

The goal of this project is the development of a control algorithm for a flock of non-holonomic aerial agents. For this purpose,the swarm architecture having some unique features such as robustness, flexibility, and scalability is utilized. Swarm is defined as a group of simple agents having local interactions between themselves and the environmentwhich shows an unpredictable emergent behavior.Behavior based control which is inspired from the animal behaviors is employed to control the swarm of mobile agents. Accordingly, the necessary behaviors which are distance adjustment, velocity agreement, and virtual leader tracking together with a fuzzy coordinator are designed. In this study, in...

Optical Flow Based Flight of a Small Fixed-Wing Aircraft in Ideal Urban Environments

, Ph.D. Dissertation Sharif University of Technology Rezaei, Mahdi (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

This thesis represents the obstacle avoidance of a fixed-wing small aircraft using optical flow information of cameras mounted on the aircraft. The thesis consists of two main sections. In section one, the ideal optical flow has been simulated based on the camera model, complete six DOF of flight equations, and the geometry of the environment. An analytical formula has been derived to relate the obstacle detection distance to the maneuverability of the aircraft. Having the obstacle detection distance, the control and navigation algorithms have been developed to achieve a collision-free flight for the aircraft in urban canyons and junctions. The effect of some parameters such as approach...

Flight Performance and Maneuverability Enhancement of a Twin Engine Fighter Aircraft Using Integrated Thrust-Vector and Aerodynamic controls

, M.Sc. Thesis Sharif University of Technology Mazinani, Morteza (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

In this thesis, maneuverability enhancement of a given twin engine fighter aircraft with integrated thrust-vector and conventional aerodynamic control surfaces havebeen studied. For this purpose a nonlinear 6DOF simulation program base on a near exact mathematical model has been prepared for the aircraft, and then a thrust vectoring system for producing moments about three body axes, like that used in F/A-18, has been added to the simulation. The control method that is employed to control the aircraft in simulation environment is based on Nonlinear Dynamic Inversion (NDI). Finally the Velocity Vector Roll (VVR) maneuver has been considered as an example tostudymaneuverability enhacement. It...

Robust Nonlinear Control of a Jet Tail-sitter UAV in Hovering Flight Phase

, M.Sc. Thesis Sharif University of Technology Sarafraz, Yasin (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

In this thesis, the theory of robust control is applied to design a controller for the longitudinal dynamics of a tail-sitter jet engine unmanned aerial vehicle. The engine thrust deflection is considered as the input controller of the system. The aircraft dynamical model is developed based on the assumption of no aerodynamic loads in low speed flight associated with the hovering condition. The controller is primarily designed using both classical and modern control techniques. Then and synthesis approaches are applied to design the robust controller. The results obtained from different approaches are compared. It is shown that the robust controller techniques are more stable and robust...

Development of a Vision-Based Position and Attitude Estimation Algorithm for Close Proximity Operation of Small Satellite

, M.Sc. Thesis Sharif University of Technology Pasand, Milad (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

One of the key technologies in the future space missions is the formation flight of small satellites. Currently, widespread research in this field is being carried out and remarkable developments have been achieved. In the mentioned laboratory researches, satellite navigation is performed by conventional sensors like infrared and ultrasonic. Both of these sensors are of active type and energy consuming. Also, use of the ultrasonic sensors is impractical in space missions (due to vacuum condition). Therefore, as an alternative for space missions, visual sensors are good candidates. The main goal of this research is to present a method for the relative navigation in proximity operations in an...

Numerical Optimization and Parametric Study of Cooperative Salvo Attack Using Particle Swarm Optimization Algorithm

, M.Sc. Thesis Sharif University of Technology Shahadati, Mohammad (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

In this research work, several guidance laws have been utilized and validated, considering the contraints on the missslie seeker angle and maximum acceleration, in order to simultaneously intercept the so-called Close-in Weapon System (CIWS) by multiple missiles. First of all, the existing guidance laws for salvo-attack are reveiwed. Then, a simulation program has been developed and validated for the misslie and CIWS as a five and two degrees of freedom systems, respectively. Optimization of the system is then carried out by the method of Particle Swarm Optimization, considering the given constraints. In the next step, for the improvement of the optimized guidance law, paramertic study has...

Machine-Vision-Based Auotomatic Landing of Unmanned Helicopter

, M.Sc. Thesis Sharif University of Technology Nasirian, Behnam (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

In this project an algorithm is designed for automatic landing of unmanned helicopter on a pad moving with six degrees of freedom. The designed controller is based on state dependent riccati equations (SDRE).by developing nonlinear mathematical model of helicopter and then converting this model to state dependent coefficient (SDC) form. A nonlinear compensator is added to controller to compensate effect of some nonlinear terms of model that are not able to translate and then state dependent riccati equations are solved.
The relative pose-estimation of landing pad is based on vision. Corner detection algorithm is used to identify and detect features by processing of image taken from...

Application of Nonlinear System Identification Techniques in the Modeling of Agile Fighter Aircraft Dynamics

, Ph.D. Dissertation Sharif University of Technology Roudbari, Alireza (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

Modeling and simulation are widely used as essential tools to predict and analyze complex systems in various scientific and engineering fields. For an aerospace system such as aircraft, mathematical models are useful used to carry out such tasks as dynamic analysis, autopilot development and combination of flight control laws, hazardous behaviors prediction, the controller design and validation, the study of the handling qualities, or the implementing simulators used for training pilots and many other tasks. In general, the aircraft flight dynamics is a nonlinear and coupled system whose dynamic modeling, in addition to pilot control inputs, depends on flight conditions (i.e., Mach and...

Experimental Investigation of Microjet Engine Anomaly Detection Based on ANN Data Clustering Analysis

, M.Sc. Thesis Sharif University of Technology Khodadadi, Mahyar (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

In this study, the possibility of detecting known and unknown anomalies in a micro jet engine is evaluated. the proposed method is neural network and clustering analysis. The process consists of two main parts, first part is experimental abnormal behavior simulation and second part is validation of proposed detection method. In the first part a micro jet engine (Olympuse HP) were used and we created pre-designed errors in engine normal behavior to record significant changes in its performance. Recorded outputs consist of six different variables: RPM, Exhaust gas temperature, Throttle command, Fuel pump voltage, Thrust and Fuel weight. In the second part, for analyzing data, we used...

Self-Reconfiguration & Autonomous Algorithm for Spacecraft Formation Flight Using Virtual Structure Approach

, M.Sc. Thesis Sharif University of Technology Sharifian, Shakib (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

One of the most important technologies in space missions is capability of moving satellites together with a predefined structure (virtual structure). This structure can reconfigure itself to any desired space mission and it is known as reconfiguration maneuver, in this maneuver all of the satellites have to follow needed virtual structure from any initial configuration to any desired second composition. In available virtual structure methods, there are a lot of limitations in maneuver because of algorithm constraints, in this project we try to extend available algorithm in virtual structure method and reach an algorithm which can start from any initial condition and complete the maneuver in...

Dynamic Modeling of a Quadrotor UAV Transporting a Variable Mass Payload Suspended by Continuous Flexible Cable

, M.Sc. Thesis Sharif University of Technology Baha, Mirshams (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

Quadrotors are one of the most popular unmanned aerial vehicle (UAVs) that has been subject of extensive research in recent years. One of the most important applications of these aerial vehicles is transporting a cable-suspended payload from one point to another. The major challenge in modeling of this system is dynamic coupling which exist between all components of the system i.e. payload, cable and quadrotor. The purpose of this research is mathematical modeling and dynamic analysis of the system in presence of this dynamic coupling and considering the effects of cable's flexibility. In this regard, it is assumed that the payload has variable mass. In this thesis, in the first step, by...

Dynamic Modelling of Multiple Quadrotor Suspended Load Transporting System with Variable Center of Mass via Flexible Cables

, M.Sc. Thesis Sharif University of Technology Latifi, Alireza (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

Using unmanned aerial vehicles in aerial payload carrying leads many changes requiring significant study and research. In recent years, there has been considerable maturation in Micro Aerial Vehicles (MAV) developement especially quadcopters. In addition to the endurance restriction, considerations on volume and weight that can be carried, and safety issues are also obstacles to the development of unmanned aerial payload carrying in urban environments. One of the ways to make a quadcopter more agile while carrying a load is to hang the cargo from the quadcopter via a cable. In this way, it is possible that quadcopters carry the cargo in a cooperative way, which if properly arranged,...

Conceptual Study of an Unmanned Water-Thrusted Aerial Firefighting System (UWFS)

, M.Sc. Thesis Sharif University of Technology Talebi, Mohammad (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

In this research work, the concept of an unmanned aerial firefighting system with water thrusters has been studied. This system consists of a platform head, a waterhose and a ground pump. The concept is briefly to pump water through the hose and then fall it down on fire from the platform. This conceptual system may have many other applications. The other applications have also been addressed in the introduction section. This platform can be considered as an unmanned aerial vehicle whose lift and control forces is provided by water thrusters. The conceptual study has been carried out based on three subjects of preliminary sizing, system dynamic modeling and controller design for platform...

Cooperative Slung-Load Transportation by Quadrotors in Urban Environment, Path Planning and Tracking

, Ph.D. Dissertation Sharif University of Technology Abeshtan, Peyman (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

In this research, the aerial load transportation in the urban environment by cooperative quadrotors is investigated. This system requires two sub-systems: path planning and control. The path planning subsystem designs the payload's path and at the same time determines the shape of the flight formation of agents in order to be able to carry the payload. The design of the path-formation is done in the presence of constraints such as the collision avoidance with obstacles, inter-collision avoidance to each other, the collision avoidance of the slung load with the obstacles and the minimum and maximum allowable cables' forces. Therefore, the shape of the formation flight is determined...

Cooperative Search and Track of Moving Targets in Urban Areas Using Unmanned Aircraft

, Ph.D. Dissertation Sharif University of Technology Karimi, Samine (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

This thesis addresses the topic of cooperative search by a group of unmanned aerial vehicles (UAVs) in a bounded region, while encountering obstacles and searching for moving targets. A review of relevant research on cooperative search for finding one or multiple targets is presented. Then, a general description of the logic of cooperative search, which is based on optimal routing by minimizing a cost function, is explained. In this context, three maps called the uncertainty map, target presence probability map, and target map are introduced. Two phases of search and tracking are defined for the UAVs, and the criteria for achieving each phase are presented. In the search phase, each UAV...