32,349 research outputs found
Finite bending and pattern evolution of the associated instability for a dielectric elastomer slab
We investigate the finite bending and the associated bending instability of
an incompressible dielectric slab subject to a combination of applied voltage
and axial compression, using nonlinear electro-elasticity theory and its
incremental version. We first study the static finite bending deformation of
the slab. We then derive the three-dimensional equations for the onset of
small-amplitude wrinkles superimposed upon the finite bending. We use the
surface impedance matrix method to build a robust numerical procedure for
solving the resulting dispersion equations and determining the wrinkled shape
of the slab at the onset of buckling. Our analysis is valid for dielectrics
modeled by a general free energy function. We then present illustrative
numerical calculations for ideal neo-Hookean dielectrics. In that case, we
provide an explicit treatment of the boundary value problem of the finite
bending and derive closed-form expressions for the stresses and electric field
in the body. For the incremental deformations, we validate our analysis by
recovering existing results in more specialized contexts. We show that the
applied voltage has a destabilizing effect on the bending instability of the
slab, while the effect of the axial load is more complex: when the voltage is
applied, changing the axial loading will influence the true electric field in
the body, and induce competitive effects between the circumferential
instability due to the voltage and the axial instability due to the axial
compression. We even find circumstances where both instabilities cohabit to
create two-dimensional patterns on the inner face of the bent sector
Future prospects of mass-degenerate Higgs bosons in the -conserving two-Higgs-doublet model
The scenario of two mass-degenerate Higgs bosons within the general
two-Higgs-doublet model (2HDM) is revisited. We focus on the global picture
when two -even Higgs bosons of and are nearly mass-degenerate. A
global fit to the signal strength of the 125 GeV Higgs measured at the LHC is
performed. Based on the best-fit result of the 2HDM mixing angles
, theoretical constraints, charged and -odd Higgs boson
direct search constraints and the electroweak precision constraints are imposed
to the 2HDM parameter space. We present the signal predictions of the channels for the benchmark models at the LHC 14 TeV runs. We also
study the direct Higgs boson pair productions at the LHC, and the Z-associated
Higgs boson pair production search at the ILC 500 GeV runs, as well as the
indirect probes at the CEPC 250 GeV run. We find that the mass-degenerate Higgs
boson scenario in the Type-II 2HDM can be fully probed by these future
experimental searches.Comment: 31 pages, 9 figures, 5 tables, matches with the PRD published versio
Schwinger boson mean field theory of the Heisenberg Ferrimagnetic Spin Chain
The Schwinger boson mean field theory is applied to the quantum ferrimagnetic
Heisenberg chain. There is a ferrimagnetic long range order in the ground
state. We observe two branches of the low lying excitation and calculate the
spin reduction, the gap of the antiferromagnetic branch, and the spin
fluctuation at . These results agree with the established numerical
results quite well. At finite temperatures, the long range order is destroyed
because of the disappearance of the Bose condensation. The thermodynamic
observables, such as the free energy, magnetic susceptibility, specific heat,
and the spin correlation at , are calculated. The has a
minimum at intermediate temperatures and the spin correlation length behaves as
at low temperatures. These qualitatively agree with the numerical
results and the difference is small at low temperatures.Comment: 15 pages, 5 figures. Accepted by Phys. Rev.
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