Highlights of CDCSS-UMD Accomplishments

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Highlights of CDCSS-UMD Accomplishments

• Presentation to Dr. Randy Zachery
• Army Research Office
• May 25, 2004 at Harvard University

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Accomplishments

• Adaptive Optics
• - Proof-of-concept experimental demonstration of
  the liquid crystal light valve (LCLV)-based high
  resolution wave-front control system (nonlinear
  Zernike filter realization)
• - Simulation results show effectiveness against
  atmospheric turbulence
• - Global nonlinear stability analysis for the
  continuous system model of the wave-front control
  system
• - Patent disclosure (PS-2001-078) jointly to
  University of Maryland and Army Research
  Laboratory Wave-front phase sensors based on
  optically or electrically controlled phase
  spatial light modulators for wave-front sensing
  and control (M.A. Vorontsov, E. W. Justh, L.
  Beresnev, P. S. Krishnaprasad, J. Ricklin)

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From nonlinear Zernike filters to high-resolution
adaptive optics
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Accomplishments

• Modeling, Computation and Control of
  Magnetostrictive Hysteresis
• - Effective numerical computation of
  magnetostrictive hysteresis in materials such as
  Terfenol-D using the Landau-Lifshitz-Gilbert
  (LLG) equation to model ferromagneto-dynamics,
  and elastic rod theory to model actuator movement
  
• - Hierarchical tree-structured Fast Multipole
  Algorithm to compute magnetostatic term in
  effective field, coupled to a new Cayley
  transform- based geometric integrator for solving
  the LLG equation, to compute theoretical
  hysteresis curves
• - Modeling of rate-dependent phenomena in
  hysteretic actuators due to eddy current effects
  by a novel extension of the Preisach model
• - Fast inversion algorithm for Preisach-type
  model to compute control signals for tracking
  specified output trajectories.
• - New Hamilton-Jacobi theory for robust control
  of hysteretic systems

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Sectional view of the Etrema magnetostrictive
actuator
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Higher Order Geometric Integrator Performance
Comparision
Comparison of integration schemes on a 2 by 2 by
4 grid, using the result of RK4 with much smaller
stepsize as the benchmark. RK4 Runge-Kutta 4-th
order, MP Mid-point rule. Cay_RK4 Cayley
transform with RK4.
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Higher Order Geometric Integrator Performance
Comparision
Comparison of performance on norm preserving
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Higher Order Geometric Integrator Summary of
Features

• Fast
• Explicit
• On the right track
• Accurate due to high order
• Norm preserving