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Davidson, Roger

Publications and source records attributed to Davidson, Roger.

Video Animation of Ocean Topography From TOPEX/POSEIDON

Three video loops showing various aspects of the dynamic ocean topography obtained from the TOPEX/POSEIDON radar altimetry data will be presented. The first shows the temporal change of the global ocean topography during the first year of the mission. The time-averaged mean is removed to reveal the temporal variabilities. Temporal interpolation is performed to create daily maps for the animation. A spatial smoothing is also performed to retain only the large-sale features. Gyre-scale seasonal changes are the main features. The second shows the temporal evolution of the Gulf Stream. The high resolution gravimetric geoid of Rapp is used to obtain the absolute ocean topography. Simulated drifters are used to visualize the flow pattern of the current. Meanders and rings of the current are the main features. The third is an animation of the global ocean topography on a spherical earth. The JGM-2 geoid is used to obtain the ocean topography...

Fu, Lee-Lueng↗

Is Large-Scale Low-Frequency Variability Satisfying Linear Barotropic Vorticity Dynamics?

What is the dynamics governing the sea level variabilities at spatial scales larger than the mesoscale and periods longer than a few weeks? This question is investigated using the TOPEX/POSEIDON altimetry data. For periods shorter than a decade, it is believed that the large-scale variabilities in the open ocean should be barotropic and can be described by the barotropic vorticity equation. To avoid the error-sensitive Laplacian operator, the above equation was integrated over a large area. Preliminary analysis was performed in the northeastern Pacific, where the eddy energy is relatively low and the bathymetry is relatively smooth. Good correlation between the two sides of the equation was obtained at periods longer than 60 days. The largest error in the data is suspected to be the ocean tides. Empirical correction for the ocean tides will be performed for further analysis. Preliminary results of a global calculation will be presented.

Fu, Lee-Lueng↗

Controls for orbital assembly of large space structures

The topics covered are presented in viewgraph form and include the following: flexible structure control; decentralized control for flexible multi-body systems; control of structures during assembly; decentralized control using structural partitioning; reduced-orded model-based controller design; ROM/residual mode filters (RMF) control of large flexible structures;RMF in a distributed parameter system (DPS); LSS active control simulation; 3-D truss beam; mobile transporter with RMS; and flexible robot manipulator.

Balas, Mark J.↗