4,062 research outputs found
Cohesive zone models in history dependent materials
Copyright @ 2013 ACMECohesive zone model is a well known concept in nonlinear fracture mechanics of elasto-plastic materials. In contrast to that, we discuss a development of the cohesive zone model to linear, but time and history dependent, materials. The stress distribution over the cohesive zone satisfies a history dependent rupture criterion for the normalised equivalent stress, represented by a nonlinear Abel-type integral operator. The cohesive zone length at each time step is determined from the condition of zero stress intensity factor at the cohesive zone tip. It appeared that the crack starts propagating after some delay time elapses since a constant load is applied to the body. This happens when the crack tip opening displacement reaches a prescribed critical value. A numerical algorithm to compute the cohesive zone and crack length with respect to time is discussed and graphs showing the results are give
Anomalous dimension and local charges
AdS space is the universal covering of a hyperboloid. We consider the action
of the deck transformations on a classical string worldsheet in . We argue that these transformations are generated by an infinite linear
combination of the local conserved charges. We conjecture that a similar
relation holds for the corresponding operators on the field theory side. This
would be a generalization of the recent field theory results showing that the
one loop anomalous dimension is proportional to the Casimir operator in the
representation of the Yangian algebra.Comment: 10 pages, LaTeX; v2: added explanations, reference
New extended Crewther-type relation
We propose a conjecture about the detailed structure of the conformal
symmetry breaking term in the generalized Crewther relation. We conclude that
this conjecture leads to new relations between the QCD expansion coefficients
of the Adler D-function and the polarized Bjorken sum rule BComment: Second part of the talk presented at RADCOR2009-9th International
Symposium on Radiative Corrections (Applications of Quantum Field Theory to
Phenomenology), October 25-30, Ascona, Switzerland, Submitted to the
Proceeding
Analysis of segregated boundary-domain integral equations for mixed variable-coefficient BVPs in exterior domains
This is the post-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2011 Birkhäuser Boston.Some direct segregated systems of boundary–domain integral equations (LBDIEs) associated with the mixed boundary value problems for scalar PDEs with variable coefficients in exterior domains are formulated and analyzed in the paper. The LBDIE equivalence to the original boundary value problems and the invertibility of the corresponding boundary–domain integral operators are proved in weighted Sobolev spaces suitable for exterior domains. This extends the results obtained by the authors for interior domains in non-weighted Sobolev spaces.The work was supported by the grant EP/H020497/1 ”Mathematical analysis of localised boundary-domain integral equations for BVPs with variable coefficients” of the EPSRC, UK
Towards active microfluidics: Interface turbulence in thin liquid films with floating molecular machines
Thin liquid films with floating active protein machines are considered.
Cyclic mechanical motions within the machines, representing microscopic
swimmers, lead to molecular propulsion forces applied to the air-liquid
interface. We show that, when the rate of energy supply to the machines exceeds
a threshold, the flat interface becomes linearly unstable. As the result of
this instability, the regime of interface turbulence, characterized by
irregular traveling waves and propagating machine clusters, is established.
Numerical investigations of this nonlinear regime are performed. Conditions for
the experimental observation of the instability are discussed.Comment: 9 pages, 8 figures, RevTeX, submitted to Physical Review
Non-linear effects in the cyclotron resonance of a massless quasi-particle in graphene
We consider the classical motion of a massless quasi-particle in a magnetic
field and under a weak electromagnetic radiation with the frequency .
Due to the non-parabolic, linear energy dispersion, the particle responds not
only at the frequency but generates a broad frequency spectrum around
it. The linewidth of the cyclotron resonance turns out to be very broad even in
a perfectly pure material which allows one to explain recent experimental data
in graphene. It is concluded that the linear response theory does not work in
graphene in finite magnetic fields.Comment: 5 pages, 4 figure
Notes on beta-deformations of the pure spinor superstring in AdS(5) x S(5)
We study the properties of the vertex operator for the beta-deformation of
the superstring in AdS(5) x S(5) in the pure spinor formalism. We discuss the
action of supersymmetry on the infinitesimal beta-deformation, the application
of the homological perturbation theory, and the relation between the worldsheet
description and the spacetime supergravity description.Comment: LaTeX, 74pp
Zero curvature representation for a new fifth-order integrable system
In this brief note we present a zero-curvature representation for one of the
new integrable system found by Mikhailov, Novikov and Wang in nlin.SI/0601046.Comment: 2 pages, LaTeX 2e, no figure
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