The Experts below are selected from a list of 15 Experts worldwide ranked by ideXlab platform
D I A Poll - One of the best experts on this subject based on the ideXlab platform.
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a first order method for the determination of the leading mass characteristics of civil transport aircraft
Aeronautical Journal, 2011Co-Authors: D I A PollAbstract:Simple, approximate relations are developed that allow rapid, yet accurate, estimates of the principal mass characteristics of modem civil transport aircraft. The method is based upon an 'aircraft mass hypothesis' combined with data taken from Type Certificates and manufacturers' information for 44 different Boeing and Airbus aircraft Types and variants. This hypothesis links the masses of the various aircraft components, including the operational items, and the maximum payload mass to just two parameters; the passenger cabin floor area, as exemplified by the 'design passenger number' and the ratio of maximum zero fuel mass to maximum take-off mass, as exemplified by the non-dimensional 'design range'. In this context, the 'design range' is defined as the maximum possible range when the aircraft is operating at its maximum zero fuel mass. This approach leads to the formulation of three basic 'laws' for aircraft mass. Special consideration is given to the identification and separation of those components that are fixed either by the design, or the certification process, and those that are free, within defined limits, to be chosen by the operator.
R Weismantel - One of the best experts on this subject based on the ideXlab platform.
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transversal numbers over subsets of linear spaces and helly Type Certificates of mixed integer infeasibility
2009Co-Authors: G Averkov, R WeismantelAbstract:Let M be a subset of R k . It is an important question in the theory of linear inequalities to estimate the minimal number h = h(M) such that every system of linear inequalities which is infeasible over M has a subsystem of at most h inequalities which is already infeasible over M. This number h(M) is said to be the Helly number of M. In view of Helly’s theorem, h(R n ) = n+1 and, by the theorem due to Doignon, Bell and Scarf, h(Z d ) = 2 d . We give a common extension of these equalities showing that h(R n ◊Z d ) = (n+1)2 d . We show that the fractional Helly number of the space M µR d (with the convexity structure induced byR d ) is at most d+ 1 as long as h(M) is finite. Finally we give estimates for the Radon number of mixed integer spaces. 2000 Mathematics Subject Classification. Primary: 52A35, 90C11; Secondary: 52C07
G Averkov - One of the best experts on this subject based on the ideXlab platform.
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transversal numbers over subsets of linear spaces and helly Type Certificates of mixed integer infeasibility
2009Co-Authors: G Averkov, R WeismantelAbstract:Let M be a subset of R k . It is an important question in the theory of linear inequalities to estimate the minimal number h = h(M) such that every system of linear inequalities which is infeasible over M has a subsystem of at most h inequalities which is already infeasible over M. This number h(M) is said to be the Helly number of M. In view of Helly’s theorem, h(R n ) = n+1 and, by the theorem due to Doignon, Bell and Scarf, h(Z d ) = 2 d . We give a common extension of these equalities showing that h(R n ◊Z d ) = (n+1)2 d . We show that the fractional Helly number of the space M µR d (with the convexity structure induced byR d ) is at most d+ 1 as long as h(M) is finite. Finally we give estimates for the Radon number of mixed integer spaces. 2000 Mathematics Subject Classification. Primary: 52A35, 90C11; Secondary: 52C07
Antonis Papachristodoulou - One of the best experts on this subject based on the ideXlab platform.
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scalable analysis of nonlinear systems using convex optimization
PhDT, 2005Co-Authors: Antonis PapachristodoulouAbstract:In this thesis, we investigate how convex optimization can be used to analyze different classes of nonlinear systems at various scales algorithmically. The methodology is based on the construction of appropriate Lyapunov-Type Certificates using sum of squares techniques. After a brief introduction on the mathematical tools that we will be using, we turn our attention to robust stability and performance analysis of systems described by Ordinary Differential Equations. A general framework for constrained systems analysis is developed, under which stability of systems with polynomial, non polynomial vector fields and switching systems, as well as estimating the region of attraction and the L2 gain can be treated in a unified manner. Examples from biology and aerospace illustrate our methodology. We then consider systems described by Functional Differential Equations (FDEs), i.e., time-delay systems. Their main characteristic is that they are infinite dimensional, which complicates their analysis. We first show how the complete Lyapunov-Krasovskii functional can be constructed algorithmically for linear time delay systems. Then, we concentrate on delay-independent and delay-dependent stability analysis of nonlinear FDEs using sum of squares techniques. An example from ecology is given. The scalable stability analysis of congestion control algorithms for the Internet is investigated next. The models we use result in an arbitrary interconnection of FDE subsystems, for which we require that stability holds for arbitrary delays, network topologies and link capacities. Through a constructive proof, we develop a Lyapunov functional for FAST - a recently developed network congestion control scheme - so that the Lyapunov stability properties scale with the system size. We also show how other network congestion control schemes can be analyzed in the same way. Finally, we concentrate on systems described by Partial Differential Equations. We show that axially constant perturbations of the Navier-Stokes equations for Hagen-Poiseuille flow are globally stable, even though the background noise is amplified as R3 where R is the Reynolds number, giving a 'robust yet fragile' interpretation. We also propose a sum of squares methodology for the analysis of systems described by parabolic PDEs. We conclude this work with an account for future research.
Hull Kevin - One of the best experts on this subject based on the ideXlab platform.
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Kevin Hull
Scholarly Commons, 2016Co-Authors: Hull KevinAbstract:For the past ten years, Kevin Hull has managed the Federal Aviation Administration’s Los Angeles Aircraft Certifcation Office in Long Beach, CA. This office is responsible for the design approval and continued operational safety of all aviation products produced in California, Arizona, Nevada and Hawaii. In 2012 his responsibilities were expanded to include design approval and continued operational safety for all civilian Unmanned Aerial Systems (UAS) in the United States. The Los Angeles Aircraft Certification Office consists of eighty engineers, flight test pilots, program managers and administrative staff and are regularly engaged with over four hundred projects at any one time. In 2012, he led a small team that resulted in issuing the first two Type Certificates for civilian UASs in the United Stated. The office is currently active in the certification process of several UAS programs. Prior to his move to the FAA, he was the Senior Manager of Airworthiness for McDonnell Douglas and then Boeing . He received his B.S. in Industrial Technology at California State University Los Angeles, minoring in law and marketing. He is also a FAA licenced Airframe and Powerplant mechanic.https://commons.erau.edu/faa-uas-bios/1014/thumbnail.jp
