88,901 research outputs found
Pilot modeling, modal analysis, and control of large flexible aircraft
The issues to be addressed are threefold. The first deals with the question of whether dynamic aeroelastic effects can significantly impact piloted flight dynamics. For example, if one were to explore this problem experimentally, what mathematical model would be appropriate to use in the simulation? What modes, for example, should be included in the simulation, or what linear model should be used in the control synthesis? The second question deals with the appropriate design criteria or design objectives. In the case of active control, for example, what would be the design objectives for the control synthesis if aeroelastic effects are a problem? The outline of the topics includes a description of a model analysis methodology aimed at answering the question of the significance of higher order dynamics. Secondly, a pilot vehicle analysis of some experimental data addresses the question of ""What's important in the task?'' The experimental data will be presented briefly, followed by the results of an open-loop modal analysis of the generic vehicle configurations in question. Finally, one of the vehicles will be augmented via active control and the results presented
Thermodynamic properties of a simple, confining model
We study the equilibrium thermodynamics of a simple, confining, DSE-model of
2-flavour QCD at finite temperature and chemical potential. The model has two
phases: one characterised by confinement and dynamical chiral symmetry
breaking; and the other by their absence. The phase boundary is defined by the
zero of the vacuum-pressure difference between the confined and deconfined
phases. Chiral symmetry restoration and deconfinement are coincident with the
transition being of first order, except for , where it is second order.
Nonperturbative modifications of the dressed-quark propagator persist into the
deconfined domain and lead to a dispersion law modified by a
dynamically-generated, momentum-dependent mass-scale. This entails that the
Stefan-Boltzmann limit for the bulk thermodynamic quantities is attained only
for large values of temperature and chemical potential.Comment: 11 pages, LaTeX, epsfig.sty, elsart.st
Time Domain Identification of an Optimal Control Pilot Model with Emphasis on the Objective Function
A method for the identification of the pilot's control compensation using time domain techniques is proposed. From this information we hope to infer a quadratic cost function, supported by the data, that represents a reasonable expression for the pilot's control objective in the task being performed, or an inferred piloting strategy. The objectives for this method are: (1) obtain a better understanding of the fundamental piloting techniques in complex tasks, such as landing approach; (2) the development of a metric measurable in simulations and flight test that correlate with subjective pilot opinion; and (3) to further validate pilot models and pilot vehicle analysis methods
Dyson-Schwinger Equations and the Quark-Gluon Plasma
We review applications of Dyson-Schwinger equations at nonzero temperature,
T, and chemical potential, mu, touching topics such as: deconfinement and
chiral symmetry restoration; the behaviour of bulk thermodynamic quantities;
the (T,mu)-dependence of hadron properties; and the possibility of diquark
condensation.Comment: 13 pages, 1 figure, LaTeX, sprocl.sty, epsfig.sty. Summary of
presentations by the authors at the Workshop "Understanding Deconfinement in
QCD", ECT*, Trento, 1-13/March, 199
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