Viljo Petäjä

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We discuss avalanche and finite-size fluctuations in a mesoscopic model to describe the shear plasticity of amorphous materials. Plastic deformation is assumed to occur through series of local reorganizations. Yield stress criteria are random while each plastic slip event induces a quadrupolar long-range elastic stress redistribution. The model is(More)
A mesoscopic model for shear plasticity of amorphous materials in two dimensions is introduced, and studied through numerical simulations in order to elucidate the macroscopic (large scale) mechanical behavior. Plastic deformation is assumed to occur through a series of local reorganizations. Using a discretization of the mechanical fields on a discrete(More)
We investigate the properties of quantum annealing applied to the random field Ising model in one, two and three dimensions. The decay rate of the residual energy, defined as the energy excess from the ground state, is find to be eres ∼ log(NMC) −ζ with ζ in the range 2...6, depending on the strength of the random field. Systems with “large clusters” are(More)
We use a power expansion representation of plane-elasticity complex potentials due to Kolossov and Muskhelishvili to compute the elastic fields induced by a localized plastic deformation event. Far from its center, the dominant contributions correspond to first-order singularities of quadrupolar and dipolar symmetry which can be associated, respectively,(More)
– We investigate by exact optimization the geometrical properties of threedimensional elastic line systems with point disorder and hard-core repulsion. The line ’forests’ become entangled due to increasing line wandering as the system height is increased, at fixed line density. There is a transition height at which a cluster of pairwise entangled lines(More)
We investigate by exact optimization methods the roughening of two and three-dimensional systems of elastic lines with point disorder and hard-core repulsion with open boundary conditions. In 2d we find logarithmic behavior whereas in 3d simple random walk -like behavior. The line ’forests’ become asymptotically completely entangled as the system height is(More)
Joint ground states of two directed polymers in a random medium are investigated. Using exact min-cost flow optimization the true two-line ground-state is compared with the single line ground state plus its first excited state. It is found that these two-line configurations are (for almost all disorder configurations) distinct implying that the true(More)
Ground states and domain walls are investigated with exact combinatorial optimization in two-dimensional random field Ising magnets. The ground states break into domains above a length scale that depends exponentially on the random field strength squared. For weak disorder, this paramagnetic structure has remnant longrange order of the percolation type. The(More)
We investigate by exact optimization method properties of twoand three-dimensional systems of elastic lines in presence of splayed columnar disorder. The ground state of many lines is separable both in two 2D and three dimensions 3D , leading to a random walk-like roughening in 2D and ballistic behavior in 3D. Furthermore, we find that in the case of pure(More)
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