Existing and Required Modeling Capabilities for Evaluating ATM Systems and Concepts

ATM systems throughout the world are entering a period of major transition and change. The combination of important technological developments and of the globalization of the air transportation industry has necessitated a reexamination of some of the fundamental premises of existing Air Traffic Management (ATM) concepts. New ATM concepts have to be examined, concepts that may place more emphasis on: strategic traffic management; planning and control; partial decentralization of decision-making; and added reliance on the aircraft to carry out strategic ATM plans, with ground controllers confined primarily to a monitoring and supervisory role. 'Free Flight' is a case in point. In order to study, evaluate and validate such new concepts, the ATM community will have to rely heavily on models and computer-based tools/utilities, covering a wide range of issues and metrics related to safety, capacity and efficiency. The state of the art in such modeling support is adequate in some respects, but clearly deficient in others. It is the objective of this study to assist in: (1) assessing the strengths and weaknesses of existing fast-time models and tools for the study of ATM systems and concepts and (2) identifying and prioritizing the requirements for the development of additional modeling capabilities in the near future. A three-stage process has been followed to this purpose: 1. Through the analysis of two case studies involving future ATM system scenarios, as well as through expert assessment, modeling capabilities and supporting tools needed for testing and validating future ATM systems and concepts were identified and described. 2. Existing fast-time ATM models and support tools were reviewed and assessed with regard to the degree to which they offer the capabilities identified under Step 1. 3 . The findings of 1 and 2 were combined to draw conclusions about (1) the best capabilities currently existing, (2) the types of concept testing and validation that can be carried out reliably with such existing capabilities and (3) the currently unavailable modeling capabilities that should receive high priority for near-term research and development. It should be emphasized that the study is concerned only with the class of 'fast time' analytical and simulation models. 'Real time' models, that typically involve humans-in-the-loop, comprise another extensive class which is not addressed in this report. However, the relationship between some of the fast-time models reviewed and a few well-known real-time models is identified in several parts of this report and the potential benefits from the combined use of these two classes of models-a very important subject-are discussed in chapters 4 and 7

Modeling and control of the departure process of congested airports

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1999.Includes bibliographical references (p. 118-121).A simple queueing model of departure operations at congested airports is proposed. This model is calibrated and validated in the case of Boston Logan airport, using runway configuration and traffic data from the Airline Service Quality Performance (ASQP) dataset. The model is then used to evaluate preliminary departure control schemes aimed at alleviating congestion on the airport surface. The potential impact of these control schemes on direct operating costs, environmental costs and overall delay is quantified and discussed. This thesis also demonstrates that the ASQP dataset does not record enough traffic to precisely identify arrival-departure interaction effects, which results in large uncertainties in the departure model. Since more complete datasets could become available in the near future, the thesis shows how such datasets could be used to reduce the departure model uncertainties.by Nicolas Pujet.Ph.D

Observational Equality: Now For Good

International audienceBuilding on the recent extension of dependent type theory with a universe of definitionally proof-irrelevant types, we introduce TT obs , a new type theory based on the setoidal interpretation of dependent type theory. TT obs equips every type with an identity relation that satisfies function extensionality, propositional extensionality, and definitional uniqueness of identity proofs (UIP). Compared to other existing proposals to enrich dependent type theory with these principles, our theory features a notion of reduction that is normalizing and provides an algorithmic canonicity result, which we formally prove in Agda using the logical relation framework of Abel et al. Our paper thoroughly develops the meta-theoretical properties of TT obs , such as the decidability of the conversion and of the type checking, as well as consistency. We also explain how to extend our theory with quotient types, and we introduce a setoidal version of Swan's Id types that turn it into a proper extension of MLTT with inductive equality

Impredicative Observational Equality

International audienceIn dependent type theory, impredicativity is a powerful logical principle that allows the definition of propositions that quantify over arbitrarily large types, potentially resulting in self-referential propositions. Impredicativity can provide a system with increased logical strength and flexibility, but in counterpart it comes with multiple incompatibility results. In particular, Abel and Coquand showed that adding definitional uniqueness of identity proofs (UIP) to the main proof assistants that support impredicative propositions (Coq and Lean) breaks the normalization procedure, and thus the type-checking algorithm. However, it was not known whether this stems from a fundamental incompatibility between UIP and impredicativity or if a more suitable algorithm could decide type-checking for a type theory that supports both. In this paper, we design a theory that handles both UIP and impredicativity by extending the recently introduced observational type theory TTobs with an impredicative universe of definitionally proof-irrelevant types, as initially proposed in the seminal work on observational equality of Altenkirch et al. We prove decidability of conversion for the resulting system, that we call CCobs , by harnessing proof-irrelevance to avoid computing with impredicative proof terms. Additionally, we prove normalization for CCobs in plain Martin-Löf type theory, thereby showing that adding proof-irrelevant impredicativity does not increase the computational content of the theory

Input-Output Modeling and Control of the Departure Process of Congested Airports

A simple queueing model of busy airport departure operations is proposed. This model is calibrated and validated using available runway configuration and traffic data. The model is then used to evaluate preliminary control schemes aimed at alleviating departure traffic congestion on the airport surface. The potential impact of these control strategies on direct operating costs, environmental costs and overall delay is quantified and discussed

Les mucorégulateurs dans les syndromes bronchiques aigus : point sur les pratiques en médecine générale et les données de la littérature

Bien que l'intérêt des mucorégulateurs au cours de la bronchite aiguë (BA) et de l'exacerbation aiguë de bronchite chronique (EABC) soit toujours débattu, leur volume de prescription demeure important en médecine générale. Dans ce contexte, nous avons voulu déterminer les convictions et les habitudes de prescription de ces médicaments par les médecins généralistes (MG). Pour cela, une enquête a été réalisée auprès d'un panel représentatif de 370 MG, auxquels trois cas cliniques ont été présentés : rhinopharyngite + BA de l'enfant, BA de l'adulte fumeur sans antécédent, et EABC non obstructive. Chaque cas clinique était suivi d'un questionnaire informatisé et standardisé. Ce travail montre que les mucorégulateurs sont souvent prescrits par les MG en cas de BA de l'enfant et de l'adulte ou d'EABC non obstructive. Cette large prescription repose sur la conviction que ces agents sont efficaces et bien tolérés. Ceci est d'ailleurs confirmé par les données de la littérature

Existing and Required Modeling Capabilities for Evaluating ATM Systems and Concepts

ATM systems throughout the world are entering a period of major transition and change. The combination of important technological developments and of the globalization of the air transportation industry has necessitated a reexamination of some of the fundamental premises of existing ATM concepts. New ATM concepts have to be examined, concepts that may place more emphasis on: strategic traffic management; planning and control; partial decentralization of decision-making; and added reliance on the aircraft to carry to strategic ATM plans, with ground controllers confined primarily to a monitoring and supervisory role. 'Free Flight' is a case in point.NASA's AATT Program under Grant No. NAG 2-99