This paper presents a preferred route selection method that includes a concept of credit points for improving collaboration between participants in Traffic Flow Management. The notion of expending credit points by users to prioritize their flights is considered for selecting alternate flight routes. Starting with a simple scenario containing a few flights, the paper presents four route selection modes for each flight, a sequential approach and aggressive, moderate and conservative user behaviors. Flights were simulated based on selected routes, with an automated system monitoring airspace constraints. With the current fidelity of the experiments, adopting a moderate or conservative approach appears to provide more benefit than being an aggressive user when all flights depart at the same time. Additionally, two different traffic scenario data (current and three times the current traffic) were used in the dynamic case to assess the utility of such a concept with timevarying schedules. Results indicate that the current implementation with moderate user behavior handles these traffic scenarios in a reasonable time and satisfies the airspace constraints.

This paper extends the concept of credit points to enhance collaboration between participants in air traffic flow management. In earlier research, a preferred route selection method was presented, where users expend credit points to prioritize the flight paths for each of their pre-departure flights. This method of prioritizing flights provides a mechanism to incorporate users' preferences in air traffic management subject to airspace congestion and weather impact constraints. In the current research, the airport arrival and departure rates at the top 70 airports are incorporated. In order to analyze the equity of arrival and departure schedules, the flight distributions at those airports were constructed for the 40 largest flight operators in the United States. The credit-points concept gives airborne flights the highest priority, enabling them to better maintain their schedule. A negotiation mechanism for participants to reassess their decisions for improved operations is described. Results for violations of arrival/departure rates and airspace constraints (due to volume and weather) before and after implementing the concept, along with credit use and incurred delays are presented. Results indicate that the credit-points concept is feasible for users to incorporate their preferences of important flights. The overall delay compared to a schedule based system reduces while maintaining airspace and airport capacities. Also, the equity increases for participating users as more constraints are added due to better utilization of available airspace.

With the evolution of the global information infrastructure, service providers will need to provide effective and adaptive resource management mechanisms that can serve more concurrent clients and deal with applications that exhibit Quality of Service (QoS) requirements. Flexible, scalable and customizable middleware can be used as enabling technology for next generation systems that adhere to the QoS requirements of applications that execute in highly dynamic distributed environments. To enable application aware resource management, we are developing a customizable and composable middleware framework called CompOSE|Q based on a reflective metamodel. In this paper, we describe the architecture and runtime environment for CompOSE|Q and briefly assess the performance overhead of the additional flexibility. We also illustrate how flexible communication mechanisms can be supported efficiently in the CompOSE|Q framework.

This paper presents an analysis of values and locations of Miles-in-Trail restrictions used within the National Airspace System over the last three years. Using specific severe weather avoidance routes, various locations are selected to implement the Miles-in-Trail restrictions to study their individual impact on the delay of flights and sector congestion in the airspace. The current traffic management operational infrastructure lacks the modeling of multiple restrictions with passback Miles-in-Trail values to upstream facilities. The model developed here allows implementation of multiple restriction locations for multiple merging streams of traffic. The model also permits speed control, vectoring or airborne holding, and passback of restrictions to upstream facilities. The simulation environment allows implementation of these restrictions, enabling a what-if capability in a rapid evaluation mode for Miles-in-Trail impact. Preliminary results are presented for delay of impacted flights due to implementation of three different playbook routes and Miles-in-Trail values at various locations with passbacks to upstream facilities. Results of sector congestion in the airspace for those cases are discussed as well. It was observed that for a particular playbook route implementation with Miles-in-Trail between 25 and 30 nmi applied at a reference fix resulted in low total delay and sector congestion. Overall, the model appears to be a good starting point for evaluation of passback restriction impact and, with operational feedback, could be used for advising passback values to upstream facilities.

Traditionally, adaptability in communication frameworks has been restricted to predefined choices without taking into consideration tradeoffs between them and the application requirements. Furthermore, different applications with an entire spectrum of requirements will have to adapt to these predefined choices instead of tailoring the communication framework to fit their needs. In this paper we extend an executable specification of a state-of-the-art secure group communication subsystem to explore two dimensions of adaptability, namely security and synchrony. In particular, we relax the traditional requirement of virtual synchrony (a well-known bottleneck) and propose various generic optimizations, while preserving essential security guarantees.