The diploma thesis addresses facility of QoS control with GNU/Linux tools iptables and iproute. An attention is focused especially on HTB and HFSC traffic shaping methods with regard to utilization in wireless networks. The paper also includes a simulation of ensuring QoS in wireless network with 802.11e amendment.

<p>The international aviation industry has embraced a revolutionary future concept of operations known as "free flight". The free flight concept allows each aircraft to travel between destinations using flexible fuel efficient routes rather than the current fixed jet routes. Flying the present inefficient fixed routes costs the airlines millions of dollars annually in fuel and personnel costs. Additionally, because there are only a limited number of the current "highways in the sky", aircraft in the United States and Europe regularly experience delays waiting for their turn to access the jet-routes. This present system also constrains future air traffic growth, particularly in oceanic airspace.</p> <p> To address these deficiencies, direct pilot-to-controller communications are required in oceanic airspace managed by the United States. This functional requirement for direct pilot-to-controller communications is not being met by the present oceanic air-to-ground communications system.</p> <p>Using a systems engineering approach, this project determines the feasibility of extending domestic air traffic control communication systems into the U.S. managed oceanic airspace over the Gulf of Mexico. Two feasible alternatives are evaluated for achieving this capability.</p> / Master of Science

Through application of modern technology, aviation systems are becoming more automated and are relying less on antiquated air traffic control (ATC) voice systems. Aircraft are now able to wirelessly broadcast and receive identity and location information using transponder technology. This helps reduce controller workload and allows the aircraft to take more responsibility for maintaining safe separation. However, these systems lack source authentication methods or the ability to check the integrity of message content. This opens the door for hackers to potentially create fraudulent messages or manipulate message content. This thesis presents a solution to handling many of the potential security issues in aircraft data communication. This is accomplished through the implementation of a Dual Path PKI (DPP) design which includes a novel approach to handling certificate revocation through session certificates. DPP defines two authentication protocols, one between aircraft and another between aircraft and ATC, to achieve source authentication. Digital signature technology is utilized to achieve message content and source integrity as well as enable bootstrapping DPP into current ATC systems. DPP employs cutting-edge elliptic curve cryptography (ECC) algorithms to increase performance and reduce overhead. T is found that the DPP design successfully mitigates several of the cyber security concerns in aircraft and ATC data communications. An implementation of the design shows that anticipated ATC systems can accommodate the additional processing power and bandwidth required by DPP to successfully achieve system integrity and security. / Master of Science

No description available.

In this work, a user-friendly MATLAB tool is introduced to solve nonlinear optimal control problems by applying collocation techniques using Coupled Radial Basis Functions (CRBFs). CRBFs are a new class of Radial Basis Functions combined with a conical spline r^5, which provides the advantage of insensitivity to the shape parameter while maintaining accuracy and robustness. To solve optimal control problems, software tools are often employed to implement numerical methods and apply advanced techniques to solving differential equations. Although several commercial software tools exist for solving optimal control problems, such as ICLOCS2, GPOPS, and DIDO, there are no options available that utilize adaptive collocation with CRBFs. A unified MATLAB tool named Radial Optimal Control Software (ROCS) is introduced and not only implements the CRBF method, but also enables any user, from professionals to students, to solve nonlinear optimal control problems through a user-friendly interface. The tool accepts user input for boundary conditions, necessary conditions, and the governing equations of motion. The two-point boundary value problem (TPBVP) is approximated through collocation using CRBFs, and the resulting nonlinear algebraic equations (NAEs) are solved with a MATLAB solver. The tool's usefulness and application are demonstrated by solving classical nonlinear optimal control problems and comparing the results with the solutions found in the literature. Compared to classical numerical method techniques, the present tool is shown to solve optimal control problems more efficiently for the same level of accuracy. By introducing this unified MATLAB tool to solving nonlinear optimal control problems, the intent is to enable professionals and students to solve nonlinear optimal control problems, e.g., in astrodynamics and space-flight mechanics, without the need for extensive manipulation of code in existing software tools and without extensive knowledge of applying numerical solvers.

Traffic signal control is an effective way to improve the efficiency of traffic networks and reduce users’ delays. Ant Colony Optimization (ACO) is a metaheuristic based on the behavior of ant colonies searching for food. ACO has successfully been used to solve many NP-hard combinatorial optimization problems and its stochastic and decentralized nature fits well with traffic flow networks. This thesis investigates the application of ACO to minimize user delay at traffic intersections. Computer simulation results show that this new approach outperforms conventional fully actuated control under the condition of high traffic demand.

This thesis deals with the development of an Airspace Sector Occupancy Model (ASOM). The model determines the occupancy of Air Traffic Control Center (ARTCC) sectors for a given geometry of sectors and flight schedules, and can be used to study the impact of alternative flight schedules on the workload imposed on the sectors. Along with complimentary airspace analysis models, this can serve as an advisory tool to approve flight plans in the Free Flight Scenario, or to reschedule flights around a Special Use Airspace (SUA). ASOM is developed using Matlab 5.2, and can be run on an IBM compatible PC, Macintosh, or Unix Workstation. The computerized model incorporates the powerful features of graphics and hierarchical modeling inherent in Matlab, to design an effective tool for analyzing air traffic scenarios and their respective sector occupancies. / Master of Science

The scope of this study was to evaluate the impact of the air traffic controller-to-pilot communication standard known as CPDLC or Data-Communication on the future air traffic operations. The impact was evaluated from the double viewpoint of airport delays and air traffic controllers' workload. RAMS simulation software is used to perform all the runs and from its output data the values of terminal area delays and controllers workload are obtained. The New York Metroplex terminal area was used as a case study. Because of its complexity, where three major airports (i.e. JFK, Newark, and La Guardia) interact and constraint each other, this area was particularly interesting to be studied and the data analyzed gave a valuable insight on the possible future impact of Data-Communication in congested terminal areas. The results of the study, based on some previous man-in-the-loop simulations performed by the FAA in the nineties, showed that significant potential benefits could be obtained with the complete implementation of such technologies in the workload experienced by air traffic controllers. Moreover some small but not negligible benefits were obtained in the total delays accrued by each airport studied. On the other hand, the simulations of the future demand predicted by the FAA demonstrated that without a significant increment in capacity or limitation on the traffic growth intolerable delays would be recorded across the NAS in the future. For the complexity of the simulation model calibration and for the very time-consuming run time not all the scenarios described in the methodology were tested, demonstrating the weakness of RAMS as a ground simulation model. / Master of Science

No description available.

Air traffic control teams are responsible for the safe and efficient control of air traffic through corresponding air sectors. When long term imbalances develop between a team's control capability and the level of control demanded by the sector traffic, inefficiencies develop in the control process. These inefficiencies are seen in sectors where traffic is delayed or rerouted due to overworked control teams, while other sectors have low levels of traffic and underutilized control teams. One technique for resolving these imbalances is to change the area of responsibility for the control team by changing the boundaries of their air sector. However, the determination of the appropriate sector boundary change for improving the situation is a qualitative question for Air Route Traffic Control Center officials. This effort reviews the existing expressions for determining the level of controller workload and presents a decision support model for quantitatively evaluating alternative sector boundary changes. A user specified workload expression is separated into workload components and describes the level of controller workload for each sector in a sectored airspace. The model requires a graphical description of the initial sector arrangement, the values for the controller workload components and a description of the proposed boundary change. The changed sector arrangement is computed from this information and the model provides a description of the resulting air sectors and their associated values for the workload components. The result of the proposed boundary change is seen in the changed sector arrangement and the amount of change is determined by comparing the values of the workload components of the initial and changed sector arrangements. Each sector arrangement is described with a data file and numerical tables. The data file is used for plotting a two-dimensional representation of the sectored airspace. The tables quantify the values of the workload components for each air route in a sector at the sector, air route, and air route section levels. In this manner, the model provides a more objective approach for officials to balance sector workloads. / M.S.