700 research outputs found
Prueba de Lowenberg
No full textPrueba de Lowenberg como prueba funcional en la valoración del sistema venoso
Experimental analysis and modelling of limit cycles in a dynamic wind tunnel rig
No full textLarge-amplitude self-sustaining periodic oscillations have been observed in an unforced pitch-axis single-degree-of-
freedom dynamic wind-tunnel rig. These limit-cycle oscillations and the associated bifurcations are caused by
aerodynamic phenomena and have been studied by constructing experimental bifurcation diagrams, where a system
parameter (horizontal tailplane deflection) is varied quasi statically and the steady-state response of the system
recorded. An innovative strategy based on these bifurcation diagrams is then used to identify a mathematical model
of the rig aerodynamics over a wide operating region. Good agreement is shown between numerical simulations of
the theoreticalmodeland experimental time histories over a large range of angle-of-attackand tailplane deflections
Real-Time Hybrid Testing of Strut-Braced Wing Under Aerodynamic Loading Using an Electrodynamic Actuator
No full textDataset for: "Real-Time Hybrid Testing of Strut-Braced Wing Under Aerodynamic Loading Using an Electrodynamic Actuator". Authors: V. Ruffini, C. Szczyglowski, D.A.W. Barton, M. Lowenberg, S.A. Neild Journal: Experimental Techniques
Design of a gain scheduled flight control system using bifurcation analysis
No full textA method for identifying regions of instability in closed-loop systems has been developed for flight dynamics applications. This forms a novel approach in which a surface of equilibria is generated in the region of interest as the influence of the control system is increased. In this way, the creation and destruction of equilibria in the controlled system can be easily found and visualized. This systematic approach allows the stability of the closed- loop system to be directly related to that of the open loop. Results are given for a highly nonlinear aircraft model and demonstrate the power of a combined analytical and graphical approach to control system synthesis
Geometric nonlinearities of aircraft systems
No full textNonlinearities due to geometric effects, in particular, via angular variables that are not small, are important for aircraft operation. Geometric nonlinearities have a strong effect on the dynamics of the aircraft system under consideration, and they are especially pronounced in aircraft ground operations. As a concrete example we consider here the effect of a non-zero rake angle on the dynamics of a nose landing gear. More specifically, we use tools from bifurcation theory to investigate the stability of the straight-rolling motion during a take-off run
Bifurcation tailoring of nonlinear systems
No full textWe discuss a novel approach to control bifurcations in nonlinear systems. The aim of bifurcation tailoring is to design an appropriate control law such that the controlled system has a desired bifurcation diagram. After describing two open-loop bifurcation tailoring techniques, this paper proposes two alternative modified bifurcation tailoring methods based on the use of the Newton-flow algorithm and the so-called Minimal Control Synthesis adaptive control strategy. The novel technique is applied to the Duffing system as an illustration example
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