23,061 research outputs found
An Improved Variable Structure Adaptive Filter Design and Analysis for Acoustic Echo Cancellation
In this research an advance variable structure adaptive Multiple Sub-Filters (MSF) based algorithm for single channel Acoustic Echo Cancellation (AEC) is proposed and analyzed. This work suggests a new and improved direction to find the optimum tap-length of adaptive filter employed for AEC. The structure adaptation, supported by a tap-length based weight update approach helps the designed echo canceller to maintain a trade-off between the Mean Square Error (MSE) and time taken to attain the steady state MSE. The work done in this paper focuses on replacing the fixed length sub-filters in existing MSF based AEC algorithms which brings refinements in terms of convergence, steady state error and tracking over the single long filter, different error and common error algorithms. A dynamic structure selective coefficient update approach to reduce the structural and computational cost of adaptive design is discussed in context with the proposed algorithm. Simulated results reveal a comparative performance analysis over proposed variable structure multiple sub-filters designs and existing fixed tap-length sub-filters based acoustic echo cancellers
On the distribution of barriers in the spin glasses
We discuss a general formalism that allows study of transitions over barriers
in spin glasses with long-range interactions that contain large but finite
number, , of spins. We apply this formalism to the Sherrington-Kirkpatrick
model with finite and derive equations for the dynamical order parameters
which allow ''instanton'' solutions describing transitions over the barriers
separating metastable states. Specifically, we study these equations for a
glass state that was obtained in a slow cooling process ending a little below
and show that these equations allow ''instanton'' solutions which erase
the response of the glass to the perturbations applied during the slow cooling
process. The corresponding action of these solutions gives the energy of the
barriers, we find that it scales as where is the reduced
temperature.Comment: 8 pages, LaTex, 2 Postscript figure
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