Italian FIRB Project on
 Parallel Algorithms and Numerical Nonlinear Optimization

Second year research advances


Research activities
  1. Perturbed dumped Newton and SQP-IP methods for discretized optimal control problems  [description]
  2. Variable projection methods: a success approach for SVMs and large-scale simply contrained QP  [description]
  3. Adaptive diagonal space-filling curves: linking geometric Lipschitz and Bayesian approaches for non-differentiable global optimization.  [description]
  4. Symbolic calculus and parallel computing for error propagation automatic control  [description]
  5. Parallel domain decomposition techniques for space-variant blurred images restoration  [description]
  6. A parallel computing approach to dynamic magnetic  resonance imaging  [description]

Research Advances


Perturbed dumped Newton and SQP-IP methods for discretized optimal control problems

Researchers. V. Ruggiero, S. Bonettini, F. Tinti.

Advances. The convergence theory of the Interior Point (IP) method for NLP problems as an Inexact Newton scheme [BGR-05, B-05] has been developed; a numerical comparison of different iterative solvers of the inner linear system (Hestenes [BGR-04], CG with indefinite preconditioners [BR-05]) has been carried out. Comparison between IP methods and semismooth schemes for the numerical solution of variational inequalities and realization of the related codes [T-05].

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Variable projection methods: a successful approach to SVMs and large-scale simply constrained QP

Researchers. L. Zanni, G. Zanghirati.

Advances. For QP problems, the projected gradient methods have been employed as inner solvers in decomposition techniques for training SVMs [Z-06] using new line-search and steplength selection strategies. In this framework, a new strategy for the selection of the working set has been developed [SZZ-05a].

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Adaptive diagonal space-filling curves: linking geometric  Lipschitz and Bayesian approaches for non-differentiable global optimization

Researchers. Ya. D. Sergeyev, D. Lera, D. Kvasov.

Advances. For the Global Optimization context, the new ideas are:

  • construction of multidimensional support function [MCGST-04] for Interval Analysis methods
  • employing of exponential sequences [S-04a]
  • feasible region partition strategy similar to the one of the diagonal methods [S-05], with only one evaluation of the objective function for each subinterval
  • classification based on the computational complexity of minimization methods [GL-05]
  • decomposition algorithms, based on the uniform norm, for Lipschitzian functions [GL-07]
  • parallel methods for the global optimization

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 Symbolic calculus and parallel computing for error propagation automatic control

Researchers. G. Spaletta.

Advances. In the Mathematica framework, the automatic derivation of Runge-Kutta methods for the solution of ODEs has been implemented [SS-04]. In [SS-06a, SS-05c] some methods exploiting the splitting and the composition for the geometric integration of ODEs are presented.

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 Parallel domain decomposition techniques for space-variant blurred images restoration

Researchers. F. Zama, E. Loli Piccolomini, G. Landi, M. Bertaja.

Advances. A descent method for the computation of the solution and of the Tikhonov regularization parameter have been applied to inverse problem coming from medical imaging, particularly from SPECT and Dynamic Magnetic Resonance (DMR) data [ZL-05, ZLL-04, LLZ-05] .

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 A parallel computing approach to dynamic magnetic  resonance imaging

Researchers. F. Zama, E. Loli Piccolomini, G. Landi, M. Bertaja.

Advances. Some nonlinear regularization methods based on the Total Variation principle have been studied in [LL-05, LLZ-04] . for the DMR problem.

 

 




Status: completed.
Info: g.zanghirati@unife.it

 Last updated: 15/3/2007.