9,400 research outputs found
Generic transient memory formation in disordered systems with noise
Out-of-equilibrium disordered systems may form memories of external driving
in a remarkable fashion. The system "remembers" multiple values from a series
of training inputs yet "forgets" nearly all of them at long times despite the
inputs being continually repeated. Here, learning and forgetting are
inseparable aspects of a single process. The memory loss may be prevented by
the addition of noise. We identify a class of systems with this behavior,
giving as an example a model of non-brownian suspensions under cyclic shear.Comment: 4 pages, 3 figure
A finite-strain hyperviscoplastic model and undrained triaxial tests of peat
This paper presents a finite-strain hyperviscoplastic constitutive model
within a thermodynamically consistent framework for peat which was categorised
as a material with both rate-dependent and thermodynamic equilibrium hysteresis
based on the data reported in the literature. The model was implemented
numerically using implicit time integration and verified against analytical
solutions under simplified conditions. Experimental studies on the undrained
relaxation and loading-unloading-reloading behaviour of an undisturbed fibrous
peat were carried out to define the thermodynamic equilibrium state during
deviatoric loading as a prerequisite for further modelling, to fit particularly
those model parameters related to solid matrix properties, and to validate the
proposed model under undrained conditions. This validation performed by
comparison to experimental results showed that the hyperviscoplastic model
could simulate undrained triaxial compression tests carried out at five
different strain rates with loading/unloading relaxation steps.Comment: 30 pages, 16 figures, 4 tables. This is a pre-peer reviewed version
of manuscript submitted to the International Journal of Numerical and
Analytical Methods in Geomechanic
Bounds and asymptotic minimal growth for Gorenstein Hilbert functions
We determine new bounds on the entries of Gorenstein Hilbert functions, both
in any fixed codimension and asymptotically.
Our first main theorem is a lower bound for the degree entry of a
Gorenstein -vector, in terms of its entry in degree . This result carries
interesting applications concerning unimodality: indeed, an important
consequence is that, given and , all Gorenstein -vectors of
codimension and socle degree (this function being
explicitly computed) are unimodal up to degree . This immediately gives a
new proof of a theorem of Stanley that all Gorenstein -vectors in
codimension three are unimodal.
Our second main theorem is an asymptotic formula for the least value that the
-th entry of a Gorenstein -vector may assume, in terms of codimension,
, and socle degree, . This theorem broadly generalizes a recent result of
ours, where we proved a conjecture of Stanley predicting that asymptotic value
in the specific case and , as well as a result of Kleinschmidt which
concerned the logarithmic asymptotic behavior in degree .Comment: Several minor changes; to appear in J. Algebr
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