Feedback Control of the National Airspace System

This paper proposes a general modeling framework adapted to the feedback control of traffic flows in Eulerian models of the National Airspace System. It is shown that the problems of scheduling and routing aircraft flows in the National Airspace System can be posed as the control of a network of queues with load-dependent service rates. Focus can then shift to developing techniques to ensure that the aircraft queues in each airspace sector, which are an indicator of the air traffic controller workloads, are kept small. This paper uses the proposed framework to develop control laws that help prepare the National Airspace System for fast recovery from a weather event, given a probabilistic forecast of capacities. In particular, the model includes the management of airport arrivals and departures subject to runway capacity constraints, which are highly sensitive to weather disruptions.National Science Foundation (U.S.) (Contract ECCS-0745237)United States. National Aeronautics and Space Administration (Contract NNA06CN24A

Audited financial statements in the federal government: Intentions, outcomes and on-going challenges for management and policy-making

The Chief Financial Officers Act of 1990 (and the subsequent Government Management Reform Act of 1994) mandated federal agencies to prepare corporate-style annual financial statements and subject them to independent audit. Over a decade later, it is reasonable to ask what the consequences of CFO Act financial statements have been. Accrual accounting produces auditable financial statements that establish accountability, contribute to the credibility of financial information, and identify long-term financial issues; but financial statements are not linked to the processes for resource-allocation decisions, nor do they produce information needed by managers. Some of these shortcomings are explained by contextual and sectoral differences