Sharif Digital Repository

An expanding flight envelope in the landing phase of a typical jet transport aircraft in presence of strong wind shears using a learning capable control system (LCCS) is investigated. The idea stems fromhuman beings functional architecture that gives them the ability to do more as they age and gain more experience. With the knowledge that classical controllers lack sufficient generality to cope with nonlinear as well as uncertain phenomenon such as turbulent air, the focuse is on different types of intelligent controllers due to their learning and nonlinear generalization capabilities as candidates for the landing flight phase. It is shown that the latter class of controllers could be used... 

In this article, we discuss the possibility of integrating image de-blurring techniques in an aerial simultaneous localization and mapping by a single camera (monocular simultaneous localization and mapping (Mono-SLAM)). We use an integrated aerial virtual environment together with a six-degree-of-freedom aircraft flight simulator to show the effectiveness of the approach to generate three-dimensional flight trajectories via integration of image de-blurring in the associated loop of the Mono-SLAM. The objective is to increase the overall performance of a flying mission over an unknown area by means of a vision-only method. The integrated aerial virtual environment produces and collects... 

Remote sensing satellites propulsion subsystem preliminary design based on performance sizing is discussed. The process is a fairly complicated one considering a variety of operational as well as performance requirements. This research aims to reduce the number of iterations required by the current practice to reach a compromise. It is based on a rapid-sizing method that helps lessen lengthy iteration cycles. The proposed technique, similar to such class of preliminary design processes, leads to an acceptable approximation that must be properly conveyed to other disciplines involved for further elaborations. With proper selection of design and performance parameters together with fundamental... 

Remote sensing satellites propulsion subsystem preliminary design based on performance sizing is discussed. The process is a fairly complicated one considering a variety of operational as well as performance requirements. This research aims to reduce the number of iterations required by the current practice to reach a compromise. It is based on a rapid-sizing method that helps lessen lengthy iteration cycles. The proposed technique, similar to such class of preliminary design processes, leads to an acceptable approximation that must be properly conveyed to other disciplines involved for further elaborations. With proper selection of design and performance parameters together with fundamental... 

A new methodology has been proposed to control the distribution of mass in an aircraft during the design and development process. Having estimated the total mass, the aircraft is considered to be composed of different segments each with an unknown mass and the equations of motion are derived based on this discritized mass model. A suitable mass distribution is then found based on the desired dynamic and static stability criterion. Using this methodology the aircraft static margin can be controlled by changing the external shape (Xac) as well as mass distribution (Xcg). By relating all applicable mass moments of inertia to the frequencies and damping ratios of longitudinal and... 

Over the last decade, there has been an increase in air transportation, which has raised awareness to provide necessary procedures to respond to air transportation demands and reduce delay costs. One such procedure, 'performance-based navigation (PBN),' currently studied, is expected to increase the airspace capacity based on aircraft's individual performances. This research describes an efficient and expandable model for allocating standard terminal arrival route during continuous descent approach (CDA) that effectively uses PBN requirements. As a case study, we have considered the 'Atlanta International Airport' and verified the model's accuracy using real-time traffic data. The model is... 

Some fundamental and unique characteristics of space are (1) global perspective, (2) above the atmosphere, (3) gravity-free environment, (4) abundant resources, and (5) exploration of space itself. If the mission doesn't rely on some fundamental and unique characteristics of space, it will likely cost more to do in space than in air or on Earth [1]. On the other hand, design of complex systems like satellites involves selecting design parameters (DPs) to satisfy the required constraints while meeting desired performance objectives. These parameters are often coupled, and their relationships not easily understood, and it makes the design an iterative process with high complexity [2]. But in... 

Purpose: The purpose of this paper is to develop a behavioral mode (as opposed to a numerical one), which considers any parasitic behavior as an indication of a potentially contributing element in the overall system deficiency. Design/methodology/approach: Similar to that associated with general systems theory, this paper concentrates on the organization and functions of natural systems which exhibit a loss of efficiency due to some general parasitic behavior. Based on the philosophy of "Bionics", it clarifies the functional architecture and root-cause of this behavior in living systems in order to model subsystems characteristics which exhibit the same behavior in a complex system. In... 

To increase crew efficiency during a long duration space mission, we have developed a Sequence Dependent Structured Matrix (SDSM) which enables designers to quickly derive the shortest paths astronauts (mission specialists) need to perform their daily tasks. This research aims to develop a new efficient tool by combining two or more DSM interpretations which help increase the ability of proper decision makings for complex situations as space travel. The results of this work have been used for arranging crew quarters in the spacecraft suited for Mars mission. In the same approach, we have been able to generalize the concept and construct different specific types of DSM; such as, Astronauts'... 

Aerial firefighting plays an integral role in containing wildfires, which have been growing rapidly in frequency and intensity over the past decades. However, the current aerial-resource management models were developed decades ago, based on the technology available then. This research aims to investigate how and what modern technologies can be integrated into aerial firefighting operation to help it keep up with the worsening situation. DSM has been used as an engineering tool to decompose the complex problem space into separate manageable segments. Using a task-based DSM, the interdependencies which give rise to unnecessary complexities are visualized, and the potential to integrate new... 

Optimal scheduling of runway operations plays an important role in improving safety and efficiency of any congested airspace. The objective of scheduling is runway assignment and computing arrival times that minimize delays and maximize runway throughput. Currently, methods for runway scheduling are categorized into First-Come-First-Serve (FCFS) and Constrained Position Shifting (CPS). In this work, we describe a new algorithm for real time scheduling for single as well as multiple parallel runway scheduling. The new approach is comparable to FCFS algorithms in accommodating practical issues while enjoying optimality similar to that of CPS methods. Different case studies show that the new... 

In this paper, the problem of designing optimal conflict-free maneuvers for multiple aircraft encounters is studied. The proposed maneuvers are based on changes of heading, speed and maneuvering time. The optimality of maneuvers among the conflict-free constraint is based on minimization of a certain cost function based on kinetic energy of either aircraft involved. Some suitable priority weight factors are incorporated into the cost function so that optimal resolution maneuvers are such that aircraft with lower priorities assume more responsibility in resolving the conflicts. As for considering aircraft turning dynamics, the circular 3-arced path with constant speed are proposed for each... 

To expedite and facilitate the certification process of a new aircraft against different climatic conditions, a new methodology has been proposed that makes use of combined advantages of both neural networks and fuzzy logic. The idea is to devise a learning capable control system that helps to decrease the number of flight tests to a minimum and, therefore, decrease the cost of the flight-test program for initial certification of an aircraft. In this approach, the certifying authorities test the learning capability of the aircraft in some preselected climatic conditions. During service life the aircraft extends its knowledge base with some suitable data collected during each flight; until it... 

An expanding flight envelope in the landing phase of a typical jet transport aircraft in presence of strong wind shears using a learning capable control system (LCCS) is investigated. The idea stems from human beings functional architecture that gives them the ability to do more as they age and gain more experience. With the knowledge that classical controllers lack sufficient generality to cope with nonlinear as well as uncertain phenomenon such as turbulent air, the focuse is on different types of intelligent controllers due to their learning and nonlinear generalization capabilities as candidates for the landing flight phase. It is shown that the latter class of controllers could be used... 

Designing an intelligent controller for landing phase of a jet transport aircraft in presence of different wind patterns, in order to expand the flight safety envelope has been considered. There are some dangerous conditions like gusts and downbursts which may occur rarely in service life of aircraft, though, aircraft must be tested for these dangerous conditions. Then it is desired to design a controller that not only acts well in usual conditions but also has an acceptable performance in those hazardous conditions. Four different types of controllers have been designed named PID, Neuro, hybrid Neuro-PID and Anfis-PID (Adaptive Network-based Fuzzy Inference System) controllers. Simulation... 

A comprehensive approach is proposed to manage landing sequences and their associated trajectories for an arbitrary number of aircraft in the vicinity of a controlled aerodrome. The current approach, similar to that of "first come, first served," could consider different types of priorities as well as emergencies. The approach is especially useful to combine unstructured free-flight trajectories with structured ones during the approach phase of the flight A comprehensive cost function considers the relative size of all aircraft together with their relative speeds and flight directions. This helps optimize the amount of fuel consumption while respecting separation minima. Resulting... 

A new methodology has been proposed to model and predict the pilot rating of a typical aircraft for flights through turbulences. The main idea here is to correlate the so-called "pilot rating" to the pilot physical energy demanded by the aircraft in a given flight condition and flying task. The proposed methodology, in addition to the other known factors, accepts the level of the human pilot physical energy consumed in each suitable period of time as well as the rate of energy consumption in the same period. These two, form the prime factors to predict the pilot rating in flying tasks that have a reasonable duration. Different case studies conducted by the authors show that for cases like... 

The main attempt of this paper is to present a new methodology to model a generic low-level flight close to terrain, which guarantees terrain collision avoidance. Benefiting the advantages of high-speed computer technology, this method uses satellite elevation maps to generate so-called "quad-tree forms". The latter is then used to find the optimal trajectories for low-level flights. The novelty of this approach, entitled the "cost map," lies in the integration of aircraft dynamics into the segmented map. This procedure results in some near-optimal trajectories with respect to aircraft dynamics that could easily be used for minimization of flight path together with pilot effort. Different... 

This work describes a new mathematical model to predict the so-called aircraft handling qualities via proper positioning of aircraft mass in the early stages of the design process. The methodology aims to help make handling qualities and therefore pilot rating an integral part of the design process. The main idea is to And proper mass distributions for an aircraft in given flight conditions based on the well-known quantitative measures of flying qualities described in military standards. The proposed methodology allows aircraft designers to associate a density to different segments of an aircraft and have a prior insight about an optimum arrangement of internal parts such as fuel tanks,...