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Syracuse University

Disordered systems and neural networks

Publication Year

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Full-Text Articles in Physics

Depinning In A Two-Layer Model Of Plastic Flow, Pierre Le Doussal, M. Cristina Marchetti, Kay Jorg Wiese Feb 2008

Depinning In A Two-Layer Model Of Plastic Flow, Pierre Le Doussal, M. Cristina Marchetti, Kay Jorg Wiese

Physics

We study a model of two layers, each consisting of a d-dimensional elastic object driven over a random substrate, and mutually interacting through a viscous coupling. For this model, the mean-field theory (i.e. a fully connected model) predicts a transition from elastic depinning to hysteretic plastic depinning as disorder or viscous coupling is increased. A functional RG analysis shows that any small inter-layer viscous coupling destablizes the standard (decoupled) elastic depinning FRG fixed point for d4 most aspects of the mean-field theory are recovered. A one-loop study at non-zero velocity indicates, for d


Mean Field Theory Of Collective Transport With Phase Slips, Karl Saunders, J. M. Schwarz, M. Cristina Marchetti, Alan Middleton Feb 2008

Mean Field Theory Of Collective Transport With Phase Slips, Karl Saunders, J. M. Schwarz, M. Cristina Marchetti, Alan Middleton

Physics

The driven transport of plastic systems in various disordered backgrounds is studied within mean field theory. Plasticity is modeled using non-convex interparticle potentials that allow for phase slips. This theory most naturally describes sliding charge density waves; other applications include flow of colloidal particles or driven magnetic flux vortices in disordered backgrounds. The phase diagrams exhibit generic phases and phase boundaries, though the shapes of the phase boundaries depend on the shape of the disorder potential. The phases are distinguished by their velocity and coherence: the moving phase generically has finite coherence, while pinned states can be coherent or incoherent ...


Driven Depinning Of Strongly Disordered Media And Anisotropic Mean-Field Limits, M. Cristina Marchetti, Alan Middleton, Karl Saunders, J. M. Schwarz Feb 2008

Driven Depinning Of Strongly Disordered Media And Anisotropic Mean-Field Limits, M. Cristina Marchetti, Alan Middleton, Karl Saunders, J. M. Schwarz

Physics

Extended systems driven through strong disorder are modeled generically using coarse-grained degrees of freedom that interact elastically in the directions parallel to the driving force and that slip along at least one of the directions transverse to the motion. A realization of such a model is a collection of elastic channels with transverse viscous couplings. In the infinite range limit this model has a tricritical point separating a region where the depinning is continuous, in the universality class of elastic depinning, from a region where depinning is hysteretic. Many of the collective transport models discussed in the literature are special ...


Weak Point Disorder In Strongly Fluctuating Flux-Line Liquids, Panayotis Benetatos, M. Cristina Marchetti Apr 2005

Weak Point Disorder In Strongly Fluctuating Flux-Line Liquids, Panayotis Benetatos, M. Cristina Marchetti

Physics

We consider the effect of weak uncorrelated quenched disorder (point defects) on a strongly fluctuating flux-line liquid. We use a hydrodynamic model which is based on mapping the flux-line system onto a quantum liquid of relativistic charged bosons in 2+1 dimensions [P. Benetatos and M. C. Marchetti, Phys. Rev. B 64, 054518, (2001)]. In this model, flux lines are allowed to be arbitrarily curved and can even form closed loops. Point defects can be scalar or polar. In the latter case, the direction of their dipole moments can be random or correlated. Within the Gaussian approximation of our hydrodynamic ...