Sharif Digital Repository

Airport saturation is one of the important issues which have always been of the specialists’ concern. One of the major applications of this subject is at the airport approach problems. While using current conventional approach procedures have many disadvantages regarding high fuel consumption and subsequent much environmental and noise pollution, the CDA concept which is one of the modern topics introduced in consequence of free flight theory, has less such disadvantages compared to conventional approach. Subject of this study is to investigate whether Procedural approach or CDA saturates an aiport sooner if the traffic flow increases. In this dissertation, using BADA database, CDA... 

The objective of this research is to model the wing structure of a flapping wing MAV and investigate structural dynamic behavior of its wing. in this research, to investigate and identify dynamic instabilities, modeling of the structure based on a nonlinear four-node plane element and aerodynamic modeling based on the strip theory in unsteady flow has been done, and by coupling these two models, the final model is formed. In the model of the wing structure, the displacement and changes angle inside the plane of the wing sections have been ignored and only outside the plane have been assumed for the degrees of freedom. In addition, the veins in the flapping wing have been omitted and the... 

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 case of rapid small satellite aerial launch by mother airplane has various applications; such as space experiment, weather monitoring, and getting information from the earth monitoring during natural disasters. In this method, the satellite and the launch vehicle will be carried up by mother airplane to the definite height; then, the launch vehicle will be released and flied - to the insert of satellite into the desired orbit. Aerial launch system success depends on a set of complex elements and their interactions. In the present study, first of all, the element interactions will be investigated by system engineering approach based on operational scenarios; then, a new approach for... 

An automatic air traffic controller system is designed in this research. The major goal is to aid the human controller in decision making at real air traffic control situations. The air traffic system is modeled by queuing theory. Since respond rapidity is very important in air traffic control, so the fuzzy logic is utilized to construct a rule-base. This rule-base determines optimum policies while considering the operational matters, minimum separation distance requirements, air traffic controller techniques, and work-load. This project is an initial design for air traffic automation system which considers scheduling optimality as well as delay reduction. The case study is done on Denver... 

This work investigates the possibility of developing suitable design guidelines for aircraft flying in very low altitude as well as terrain following flights (TFF). The work aims to highlight the TFF mission in the early stages of design process; as oppose to other mission conducted by the aircraft. Current approach in TFF relies heavily on efficient Flight Control System (FCS) regardless of the overall configuration of aircraft. However, in this work, we show not all aircraft in the service could conduct TFF and maneuverability of airplane is very important. In fact, we investigate the overall impact of TFF on the wing loading (W/S) and thrust loading (T/W); if we were to design an aircraft... 

Functional Requirements (FR) are traditionally known to be "input" as far as an engineering process is concerned. However, for a Systems Engineer (SE), this is not the case. A well-known task of a SE is, in fact, to develop FRs from what is considered as the customer needs. The traditional approach to develop suitable FRs involves an algorithmic procedure; which mostly relies on the skills, knowledge, attitude, and experiences of the SE or experts members of design team. It is therefore an ad-hoc method which results in quite a few numbers of trial-errors and its effectiveness only reveals itself as time goes on. The current work aims to address such a shortcoming in Systems Engineering... 

This work describes a methodology to enhance aircraft performance via proper mass distribution management. The methodology aims to limit aircraft configuration in early stages of the design process to its desired performance. Mass Distribution Management (MDM), that is used in this work, is a new mathematical model which predicts the so-called aircraft Handling Qualities (HQ) via proper positioning of aircraft mass. This work shows how proper changes in B-747-100 fuel tanks arrangement can enhance its flight quality up to level one during its entire cruise flight without use of any stability augmentation systems. In general this work introduce a methodology to examine different fuel tanks... 

Towards basic-applied Research in the System Sciences fields, this Research has been to try to understand the behavior patterns and Functional Architecture of parasitic organisms and Use these in Social-Economic Systems. In this research four scenarios for parasite behavior were found and based on one of them, the recent "Financial Crisis in Greece" has been evaluated. The results show that the developed model, can be effective in similar conditions.
 

Airline scheduling is a dynamic process in nature such that it changes not only during one year period but also in smaller intervals due to the economic, political, religious, and social factors. Basically, airlines schedule planners through using mathematical models decide which flights are to be served in what periods of time and at what costs. This has to be done considering a set of constraints of different nature, from airspace and airport congestion up to climatic conditions or even crews working conditions. Such a complex problem requires different methods for an efficient solution. In this study by using network optimization method and applying different operational constraints on... 

In order to manage a complex system, one way is to divide it into smaller parts. That’s the reason airspace in each country should be divided into sectors. Currently, these sectors have fixed areas and each is controlled by a number of air traffic controllers. However, the traffic crossing these sectors is considerably dynamic, which means the traffic density and its distribution varies seasonally, weakly and even through the 24 hours of a day. Moreover, weather conditions and security and military issues make constraints to some of these sectors. This sometimes results in some high traffic sectors while some others have very low traffic density which causes two main problems. One is that,... 

In this study, a model for the optimal routes for the recovery of space debris is expressed. The dynamic model using a binary system consisting of satellites and orbital debris containment space is extracted. Trastrhay available on satellite and aerodynamic drag on the system circuit changes the whole system and the entry of debris into the thick atmosphere began to burn.This circuit must be optimized. The thrusters are assumed as variable optimization problem. After simulation of optimization, it follows that by changing the initial value thrusters, Trastrhay the optimal cost function changes. Also, indicating the final height of system affects on parameters, thrusters and the cost... 

For the past few years, increasing the airspace capacity has been one of the most detrimental issues facing air traffic management. Statistically speaking, the demand for aerial transportation has been continuously growing hitting an %8.1 growth in 2017. This growth rate in conjunction with the performance and safety considerations for the ATC systems, clearly indicate the need for a practical and safe solution to the airspace capacity problem. Dynamic Airspace Configuration (DAC), is one of the proposed methods addressing this problem by changing the airspace configuration over time.In this research, we have introduced an intelligent method for airspace configuration given the forecast of... 

According to predictions of big airlines, demand of aerial transportation is rapidly increasing. This jump in aerial traffic is concerning environment activists as well as air traffic control centers. New proposed solutions such as designing new aircrafts and new fuels, require basic infrastructure and take a lot of time. Among these solutions, formation flight is an available answer to the problem as it is consistent with existing infrastructure. In this study, a robust model is proposed in which any kind of aircraft can decide to whether enter or exit a formation, and the formation problem is changed from a static problem to a dynamic one. The runtime is of a scale which can be used as an... 

In this Thesis, the necessary steps to implement near-optimal atmospheric flights in order to create micro and partial gravity condition has specified. This documentary has been prepared in a comprehensive way. The goal of this project is to reach the optimal throttle and elevator inputs and consequently optimal paths to perform the maneuver with maximum time. The basis of my work is to integrate two methods of tabu search and continuous ant colony system in order to find the best match for inputs. As a result, the aircraft’s proper inputs as a function of time can be accommodated. The constraints here refers to the safety of the flight, which are maximum operating speed, stall angle of... 

The article describes a new algorithm for the en-route conflict detection and resolution problem for flying aircrafts. In this new algorithm both horizontal and vertical maneuvers are considered. The proposed conflict resolution trajectories are optimized in the sense that they respect minimum deviation from the original path planned by all aircraft involved in the discovered conflict. The proposed horizontal maneuvers consists of three consecutive turns that guarantees return to the original path and can be done in both cooperative or non-cooperative manner. The algorithm searches different scenarios for conflict resolution between multiple aircrafts while preventing secondary conflicts.... 

This work describes a new approach to the so called “Engineering Requirements Process” based on abilities to develop a meaningful task. We first describe how a meaningful is created from scratch and then we explain how requirements could be added to a level where the predefined task is no-longer doable. The process is then applied to design of an aircraft wing to show how requirements could be avoided during a design process. The method is expected to be applicable to all aircraft sub-systems and parts. The process is particularly useful where all design requirements are not available at once, rather they increase as time goes on and new stakeholders become apparent. In this work, we have... 

The existing trend in air transportation growth, clearly shows that aviation industries need to profoundly look at “formation flights” in a more efficient manner and without complex computations. This work describes a new efficient Logic to accept or reject a possible formation among all available. The approach considers each airplane as an agents that “sees” the current traffic environment and then selects the best “Action” to satisfy its desired objectives. The logic, although simple, considers the location and time to join a formation or to create one; and the position to leave the original formation. Different Mathematical model have been investigated to find-out which one is more... 

Nowadays more than half of the world’s population lived in urban areas. That proportion is set to rise to 67% by 2050. This will cause urban mobility with serious problems. The concept of Urban Air Mobility (UAM) is proposed to avoid the problem to become a catastrophy. Due to environmental issues and also high operating costs, using copters as an air-taxi was not justifiable. As the technology in e-VTOL flourished, the desire of using of these vehicles in such a transportation system was increased. In this paper, besides previous investigations, the e-VTOL’s performance parameters’ influence on the characteristic of a civil air-taxi network is under investigation. In addition, this paper... 

In the class of unmanned air vehicles (UAV), there is a class entitled as Quad-rotor that engineers pay much attention due to specific features to them. Main applications of this class are because of vertical take-off and landing capability and high controllability. This class has high controllability in environments with high barriers because of the inherent imbalance. All of the Quad-rotors have already studied, had a fixed structure. So the designer's main focus was on improving the guidance and control systems and almost all forms of linear and nonlinear control methods and fuzzy, adaptive and robust control have been investigated. In this study variable structure is examined instead...