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2018-03-15
|
Improving the capacity of quantum dense coding by weak measurement and reversal measurement
|
A protocol of quantum dense coding protection of two qubits is proposed in
amplitude damping (AD) channel using weak measurement and reversal measurement.
It is found that the capacity of quantum dense coding under the weak
measurement and reversal measurement is always greater than that without weak
measurement and reversal measurement. When the protocol is applied, for the AD
channels with different damping coefficient, the result reflects that quantum
entanglement can be protected and quantum dense coding becomes successful.
|
1803.05678v1
|
2018-05-08
|
Optomechanical damping as the origin of sideband asymmetry
|
Sideband asymmetry in cavity optomechanics has been explained by particle
creation and annihilation processes, which bestow an amplitude proportional to
'n+1' and 'n' excitations to each of the respective sidebands. We discuss the
issues with this as well as other interpretations, such as quantum backaction
and noise interference, and show that the asymmetry is due to the
optomechanical damping caused by the probe and the cooling lasers instead.
|
1805.02952v4
|
2018-05-11
|
On the asymptotic stability of stratified solutions for the 2D Boussinesq equations with a velocity damping term
|
We consider the 2D Boussinesq equations with a velocity damping term in a
strip $\mathbb{T}\times[-1,1]$, with impermeable walls. In this physical
scenario, where the \textit{Boussinesq approximation} is accurate when
density/temperature variations are small, our main result is the asymptotic
stability for a specific type of perturbations of a stratified solution. To
prove this result, we use a suitably weighted energy space combined with linear
decay, Duhamel's formula and "bootstrap" arguments.
|
1805.05179v2
|
2018-06-30
|
A linearized and conservative Fourier pseudo-spectral method for the damped nonlinear Schrödinger equation in three dimensions
|
In this paper, we propose a linearized Fourier pseudo-spectral method, which
preserves the total mass and energy conservation laws, for the damped nonlinear
Schr\"{o}dinger equation in three dimensions. With the aid of the semi-norm
equivalence between the Fourier pseudo-spectral method and the finite
difference method, an optimal $L^2$-error estimate for the proposed method
without any restriction on the grid ratio is established by analyzing the real
and imaginary parts of the error function. Numerical results are addressed to
confirm our theoretical analysis.
|
1807.00091v3
|
2018-07-11
|
Global existence and blow-up for semilinear damped wave equations in three space dimensions
|
We consider initial value problem for semilinear damped wave equations in
three space dimensions. We show the small data global existence for the problem
without the spherically symmetric assumption and obtain the sharp lifespan of
the solutions. This paper is devoted to a proof of the Takamura's conjecture on
the lifespan of solutions.
|
1807.04327v3
|
2018-07-18
|
B-field induced mixing between Langmuir waves and axions
|
We present an analytic study of the dispersion relation for an isotropic
magnetized plasma interacting with axions. We provide a quantitative picture of
the electromagnetic plasma oscillations in both the ultrarelativistic and
nonrelativistic regimes and considering both non-degenerate and degenerate
media, accounting for the dispersion curves as a function of the plasma
temperature and the ratio of the plasma phase velocity to the characteristic
velocity of particles. We include the modifications on the Landau damping of
plasma waves induced by the presence of the axion field, and we comment on the
effects of damping on subluminal plasma oscillations.
|
1807.06828v2
|
2018-07-26
|
Moment conditions and lower bounds in expanding solutions of wave equations with double damping terms
|
In this report we obtain higher order asymptotic expansions of solutions to
wave equations with frictional and viscoelastic damping terms. Although the
diffusion phenomena are dominant, differences between the solutions we deal
with and those of heat equations can be seen by comparing the second order
expansions of them. In order to analyze such effects we consider the weighted
L1 initial data. We also give some lower bounds which show the optimality of
obtained expansions.
|
1807.10020v1
|
2018-08-16
|
Continuity of the set equilibria of non-autonomous damped wave equations with terms concentrating on the boundary
|
In this paper we are interested in the behavior of the solutions of
non-autonomous damped wave equations when some reaction terms are concentrated
in a neighborhood of the boundary and this neighborhood shrinks to boundary as
a parameter \varepsilon goes to zero. We prove the conti- nuity of the set
equilibria of these equations. Moreover, if an equilibrium solution of the
limit problem is hyperbolic, then we show that the per- turbed equation has one
and only one equilibrium solution nearby.
|
1808.05667v1
|
2018-08-30
|
Protecting temporal correlations of two-qubit states using quantum channels with memory
|
Quantum temporal correlations exhibited by violations of Leggett-Garg
Inequality (LGI) and Temporal Steering Inequality (TSI) are in general found to
be non-increasing under decoherence channels when probed on two-qubit pure
entangled states. We study the action of decoherence channels, such as
amplitude damping, phase-damping and depolarising channels when partial memory
is introduced in a way such that two consecutive uses of the channels are
time-correlated. We show that temporal correlations demonstrated by violations
of the above temporal inequalities can be protected against decoherence using
the effect of memory.
|
1808.10345v1
|
2018-09-17
|
Global existence for weakly coupled systems of semi-linear structurally damped $σ$-evolution models with different power nonlinearities
|
In this paper, we study the Cauchy problems for weakly coupled systems of
semi-linear structurally damped $\sigma$-evolution models with different power
nonlinearities. By assuming additional $L^m$ regularity on the initial data,
with $m \in [1,2)$, we use $(L^m \cap L^2)- L^2$ and $L^2- L^2$ estimates for
solutions to the corresponding linear Cauchy problems to prove the global (in
time) existence of small data Sobolev solutions to the weakly coupled systems
of semi-linear models from suitable function spaces.
|
1809.06744v2
|
2018-09-25
|
On the energy decay rates for the 1D damped fractional Klein-Gordon equation
|
We consider the fractional Klein-Gordon equation in one spatial dimension,
subjected to a damping coefficient, which is non-trivial and periodic, or more
generally strictly positive on a periodic set. We show that the energy of the
solution decays at the polynomial rate $O(t^{-\frac{s}{4-2s}})$ for $0< s<2 $
and at some exponential rate when $s\geq 2$. Our approach is based on the
asymptotic theory of $C_0$ semigroups in which one can relate the decay rate of
the energy in terms of the resolvent growth of the semigroup generator. The
main technical result is a new observability estimate for the fractional
Laplacian, which may be of independent interest.
|
1809.09531v1
|
2018-10-15
|
Global well-posedness in the critical Besov spaces for the incompressible Oldroyd-B model without damping mechanism
|
We prove the global well-posedness in the critical Besov spaces for the
incompressible Oldroyd-B model without damping mechanism on the stress tensor
in $\mathbb{R}^d$ for the small initial data. Our proof is based on the
observation that the behaviors of Green's matrix to the system of
$\big(u,(-\Delta)^{-\frac12}\mathbb{P}\nabla\cdot\tau\big)$ as well as the
effects of $\tau$ change from the low frequencies to the high frequencies and
the construction of the appropriate energies in different frequencies.
|
1810.06171v1
|
2018-10-18
|
Global solutions to the $n$-dimensional incompressible Oldroyd-B model without damping mechanism
|
The present work is dedicated to the global solutions to the incompressible
Oldroyd-B model without damping on the stress tensor in $\mathbb{R}^n(n=2,3)$.
This result allows to construct global solutions for a class of highly
oscillating initial velocity. The proof uses the special structure of the
system. Moreover, our theorem extends the previous result by Zhu [19] and
covers the recent result by Chen and Hao [4].
|
1810.08048v3
|
2018-10-30
|
Global well-posedness for nonlinear wave equations with supercritical source and damping terms
|
We prove the global well-posedness of weak solutions for nonlinear wave
equations with supercritical source and damping terms on a three-dimensional
torus $\mathbb T^3$ of the prototype \begin{align*} &u_{tt}-\Delta
u+|u_t|^{m-1}u_t=|u|^{p-1}u, \;\; (x,t) \in \mathbb T^3 \times \mathbb R^+ ;
\notag\\ &u(0)=u_0 \in H^1(\mathbb T^3)\cap L^{m+1}(\mathbb T^3), \;\;
u_t(0)=u_1\in L^2(\mathbb T^3), \end{align*} where $1\leq p\leq \min\{
\frac{2}{3} m + \frac{5}{3} , m \}$. Notably, $p$ is allowed to be larger than
$6$.
|
1810.12476v1
|
2018-11-02
|
Nonlinear Damped Timoshenko Systems with Second Sound - Global Existence and Exponential Stability
|
In this paper, we consider nonlinear thermoelastic systems of Timoshenko type
in a one-dimensional bounded domain. The system has two dissipative mechanisms
being present in the equation for transverse displacement and rotation angle -
a frictional damping and a dissipation through hyperbolic heat conduction
modelled by Cattaneo's law, respectively. The global existence of small, smooth
solutions and the exponential stability in linear and nonlinear cases are
established.
|
1811.01128v1
|
2018-11-14
|
Quantum witness of a damped qubit with generalized measurements
|
We evaluate the quantum witness based on the no-signaling-in-time condition
of a damped two-level system for nonselective generalized measurements of
varying strength. We explicitly compute its dependence on the measurement
strength for a generic example. We find a vanishing derivative for weak
measurements and an infinite derivative in the limit of projective
measurements. The quantum witness is hence mostly insensitive to the strength
of the measurement in the weak measurement regime and displays a singular,
extremely sensitive dependence for strong measurements. We finally relate this
behavior to that of the measurement disturbance defined in terms of the
fidelity between pre-measurement and post-measurement states.
|
1811.06013v1
|
2018-12-11
|
Blow up of solutions to semilinear non-autonomous wave equations under Robin boundary conditions
|
The problem of blow up of solutions to the initial boundary value problem for
non-autonomous semilinear wave equation with damping and accelerating terms
under the Robin boundary condition is studied. Sufficient conditions of blow up
in a finite time of solutions to semilinear damped wave equations with
arbitrary large initial energy are obtained. A result on blow up of solutions
with negative initial energy of semilinear second order wave equation with
accelerating term is also obtained.
|
1812.04595v1
|
2018-12-23
|
Global existence of weak solutions for strongly damped wave equations with nonlinear boundary conditions and balanced potentials
|
We demonstrate the global existence of weak solutions to a class of
semilinear strongly damped wave equations possessing nonlinear hyperbolic
dynamic boundary conditions. Our work assumes $(-\Delta_W)^\theta \partial_tu$
with $\theta\in[\frac{1}{2},1)$ and where $\Delta_W$ is the Wentzell-Laplacian.
Hence, the associated linear operator admits a compact resolvent. A balance
condition is assumed to hold between the nonlinearity defined on the interior
of the domain and the nonlinearity on the boundary. This allows for arbitrary
(supercritical) polynomial growth on each potential, as well as mixed
dissipative/anti-dissipative behavior. Moreover, the nonlinear function defined
on the interior of the domain is assumed to be only $C^0$.
|
1812.09781v1
|
2018-12-24
|
Cold Damping of an Optically Levitated Nanoparticle to micro-Kelvin Temperatures
|
We implement a cold damping scheme to cool one mode of the center-of-mass
motion of an optically levitated nanoparticle in ultrahigh vacuum from room
temperature to a record-low temperature of 100 micro-Kelvin. The measured
temperature dependence on feedback gain and thermal decoherence rate is in
excellent agreement with a parameter-free model. We determine the
imprecision-backaction product for our system and provide a roadmap towards
ground-state cooling of optically levitated nanoparticles.
|
1812.09875v1
|
2019-01-18
|
Decay of semilinear damped wave equations:cases without geometric control condition
|
We consider the semilinear damped wave equation $\partial_{tt}^2
u(x,t)+\gamma(x)\partial_t u(x,t)=\Delta u(x,t)-\alpha u(x,t)-f(x,u(x,t))$. In
this article, we obtain the first results concerning the stabilization of this
semilinear equation in cases where $\gamma$ does not satisfy the geometric
control condition. When some of the geodesic rays are trapped, the
stabilization of the linear semigroup is semi-uniform in the sense that
$\|e^{At}A^{-1}\|\leq h(t)$ for some function $h$ with $h(t)\rightarrow 0$ when
$t\rightarrow +\infty$. We provide general tools to deal with the semilinear
stabilization problem in the case where $h(t)$ has a sufficiently fast decay.
|
1901.06169v1
|
2019-02-04
|
Non-Markovian Effects on Overdamped Systems
|
We study the consequences of adopting the memory dependent, non-Markovian,
physics with the memory-less over-damped approximation usually employed to
investigate Brownian particles. Due to the finite correlation time scale
associated with the noise, the stationary behavior of the system is not
described by the Boltzmann-Gibbs statistics. However, the presence of a very
weak external white noise can be used to regularize the equilibrium properties.
Surprisingly, the coupling to another bath effectively restores the dynamical
aspects missed by the over-damped treatment.
|
1902.01356v1
|
2019-02-06
|
Stability analysis of a 1D wave equation with a nonmonotone distributed damping
|
This paper is concerned with the asymptotic stability analysis of a one
dimensional wave equation subject to a nonmonotone distributed damping. A
well-posedness result is provided together with a precise characterization of
the asymptotic behavior of the trajectories of the system under consideration.
The well-posedness is proved in the nonstandard L p functional spaces, with p
$\in$ [2, $\infty$], and relies mostly on some results collected in Haraux
(2009). The asymptotic behavior analysis is based on an attractivity result on
a specific infinite-dimensional linear time-variant system.
|
1902.02050v1
|
2019-02-13
|
Comment on "Quantization of the damped harmonic oscillator" [Serhan et al, J. Math. Phys. 59, 082105 (2018)]
|
A recent paper [J. Math. Phys. {\bf 59}, 082105 (2018)] constructs a
Hamiltonian for the (dissipative) damped harmonic oscillator. We point out that
non-Hermiticity of this Hamiltonian has been ignored to find real discrete
eigenvalues which are actually non-real. We emphasize that non-Hermiticity in
Hamiltonian is crucial and it is a quantal signature of dissipation.
|
1902.04895v1
|
2019-02-15
|
Memory effects teleportation of quantum Fisher information under decoherence
|
We have investigated how memory effects on the teleportation of quantum
Fisher information(QFI) for a single qubit system using a class of X-states as
resources influenced by decoherence channels with memory, including amplitude
damping, phase-damping and depolarizing channels. Resort to the definition of
QFI, we first derive the explicit analytical results of teleportation of QFI
with respect to weight parameter $\theta$ and phase parameter $\phi$ under the
decoherence channels. Component percentages, the teleportation of QFI for a
two-qubit entanglement system has also been addressed. The remarkable
similarities and differences among these two situations are also analyzed in
detail and some significant results are presented.
|
1902.05668v1
|
2019-02-23
|
Uniform decay rates for a suspension bridge with locally distributed nonlinear damping
|
We study a nonlocal evolution equation modeling the deformation of a bridge,
either a footbridge or a suspension bridge. Contrarily to the previous
literature we prove the asymptotic stability of the considered model with a
minimum amount of damping which represents less cost of material. The result is
also numerically proved.
|
1902.09963v1
|
2019-03-01
|
Spectra of the Dissipative Spin Chain
|
This paper generalizes the (0+1)-dimensional spin-boson problem to the
corresponding (1+1)-dimensional version. Monte Carlo simulation is used to find
the phase diagram and imaginary time correlation function. The real frequency
spectrum is recovered by the newly developed P\'ade regression analytic
continuation method. We find that, as dissipation strength $\alpha$ is
increased, the sharp quasi-particle spectrum is broadened and the peak
frequency is lower. According to the behavior of the low frequency spectrum, we
classify the dynamical phase into three different regions: weakly damped,
linear $k$-edge, and strongly damped.
|
1903.00567v1
|
2019-03-17
|
Sensing Kondo correlations in a suspended carbon nanotube mechanical resonator with spin-orbit coupling
|
We study electron mechanical coupling in a suspended carbon nanotube (CNT)
quantum dot device. Electron spin couples to the flexural vibration mode due to
spin-orbit coupling in the electron tunneling processes. In the weak coupling
limit, i.e. electron-vibration coupling is much smaller than the electron
energy scale, the damping and resonant frequency shift of the CNT resonator can
be obtained by calculating the dynamical spin susceptibility. We find that
strong spin-flip scattering processes in Kondo regime significantly affect the
mechanical motion of the carbon nanotube: Kondo effect induces strong damping
and frequency shift of the CNT resonator.
|
1903.07049v1
|
2019-03-27
|
Lifespan of semilinear generalized Tricomi equation with Strauss type exponent
|
In this paper, we consider the blow-up problem of semilinear generalized
Tricomi equation. Two blow-up results with lifespan upper bound are obtained
under subcritical and critical Strauss type exponent. In the subcritical case,
the proof is based on the test function method and the iteration argument. In
the critical case, an iteration procedure with the slicing method is employed.
This approach has been successfully applied to the critical case of semilinear
wave equation with perturbed Laplacian or the damped wave equation of
scattering damping case. The present work gives its application to the
generalized Tricomi equation.
|
1903.11351v2
|
2019-04-01
|
A remark on semi-linear damped $σ$-evolution equations with a modulus of continuity term in nonlinearity
|
In this article, we indicate that under suitable assumptions of a modulus of
continuity we obtain either the global (in time) existence of small data
Sobolev solutions or the blow-up result of local (in time) Sobolev solutions to
semi-linear damped $\sigma$-evolution equations with a modulus of continuity
term in nonlinearity.
|
1904.00698v3
|
2019-04-05
|
Critical regularity of nonlinearities in semilinear classical damped wave equations
|
In this paper we consider the Cauchy problem for the semilinear damped wave
equation
$u_{tt}-\Delta u + u_t = h(u);\qquad u(0;x) = f(x); \quad u_t(0;x) = g(x);$
where $h(s) = |s|^{1+2/n}\mu(|s|)$. Here n is the space dimension and $\mu$
is a modulus of continuity. Our goal is to obtain sharp conditions on $\mu$ to
obtain a threshold between global (in time) existence of small data solutions
(stability of the zerosolution) and blow-up behavior even of small data
solutions.
|
1904.02939v1
|
2019-04-29
|
Origin of the DAMPE 1.4 TeV peak
|
Recent accurate measurements of cosmic ray electron flux by the Dark Matter
Particle Explorer (DAMPE) reveal a sharp peak structure near 1.4 TeV, which is
difficult to explain by standard astrophysical processes. In this letter, we
propose a simple model that the enhanced dark matter annihilation via the
$e^+e^-$ channel and with the thermal relic annihilation cross section around
the current nearest black hole (A0620-00) can satisfactorily account for the
sharp peak structure. The predicted dark matter mass is $\sim 1.5-3$ TeV.
|
1904.12418v1
|
2019-05-07
|
Decay estimate for the solution of the evolutionary damped $p$-Laplace equation
|
In this note, we study the asymptotic behavior, as $t$ tends to infinity, of
the solution $u$ to the evolutionary damped $p$-Laplace equation
\begin{equation*}
u_{tt}+a\, u_t =\Delta_p u \end{equation*}
with Dirichlet boundary values. Let $u^*$ denote the stationary solution with
same boundary values, then the $W^{1,p}$-norm of $u(t) - u^{*}$ decays for
large $t$ like $t^{-\frac{1}{(p-1)p}}$, in the degenerate case $ p > 2$.
|
1905.03597v2
|
2019-05-10
|
Asymptotic profiles for damped plate equations with rotational inertia terms
|
We consider the Cauchy problem for plate equations with rotational inertia
and frictional damping terms. We will derive asymptotic profiles of the
solution in L^2-sense as time goes to infinity in the case when the initial
data have high and low regularity, respectively. Especially, in the low
regularity case of the initial data one encounters the regularity-loss
structure of the solutions, and the analysis is more delicate. We employ the
so-called Fourier splitting method combined with the explicit expression of the
solutions (high frequency estimates) and the method due to Ikehata (low
frequency estimates).
|
1905.04012v1
|
2019-05-20
|
Small perturbations for a Duffing-like evolution equation involving non-commuting operators
|
We consider an abstract evolution equation with linear damping, a nonlinear
term of Duffing type, and a small forcing term. The abstract problem is
inspired by some models for damped oscillations of a beam subject to external
loads or magnetic fields, and shaken by a transversal force.
The main feature is that very natural choices of the boundary conditions lead
to equations whose linear part involves two operators that do not commute.
We extend to this setting the results that are known in the commutative case,
namely that for asymptotically small forcing terms all solutions are eventually
close to the three equilibrium points of the unforced equation, two stable and
one unstable.
|
1905.07942v1
|
2019-05-30
|
A study of coherence based measure of quantumness in (non) Markovian channels
|
We make a detailed analysis of quantumness for various quantum noise
channels, both Markovian and non-Markovian. The noise channels considered
include dephasing channels like random telegraph noise, non-Markovian dephasing
and phase damping, as well as the non-dephasing channels such as generalized
amplitude damping and Unruh channels. We make use of a recently introduced
witness for quantumness based on the square $l_1$ norm of coherence. It is
found that the increase in the degree of non-Markovianity increases the
quantumness of the channel.
|
1905.12872v1
|
2019-05-30
|
Stabilization for vibrating plate with singular structural damping
|
We consider the dynamic elasticity equation, modeled by the Euler-Bernoulli
plate equation, with a locally distributed singular structural (or viscoelastic
) damping in a boundary domain. Using a frequency domain method combined, based
on the Burq's result, combined with an estimate of Carleman type we provide
precise decay estimate showing that the energy of the system decays
logarithmically as the type goes to the infinity.
|
1905.13089v1
|
2019-06-12
|
A no-go result for the quantum damped harmonic oscillator
|
In this letter we show that it is not possible to set up a canonical
quantization for the damped harmonic oscillator using the Bateman lagrangian.
In particular, we prove that no square integrable vacuum exists for the {\em
natural} ladder operators of the system, and that the only vacua can be found
as distributions. This implies that the procedure proposed by some authors is
only formally correct, and requires a much deeper analysis to be made rigorous.
|
1906.05121v2
|
2019-06-26
|
Mismatched Estimation of Polynomially Damped Signals
|
In this work, we consider the problem of estimating the parameters of
polynomially damped sinusoidal signals, commonly encountered in, for instance,
spectroscopy. Generally, finding the parameter values of such signals
constitutes a high-dimensional problem, often further complicated by not
knowing the number of signal components or their specific signal structures. In
order to alleviate the computational burden, we herein propose a mismatched
estimation procedure using simplified, approximate signal models. Despite the
approximation, we show that such a procedure is expected to yield predictable
results, allowing for statistically and computationally efficient estimates of
the signal parameters.
|
1906.11113v1
|
2019-06-27
|
Temperature-Dependent Lifetimes of Low-Frequency Adsorbate Modes from Non-Equilibrium Molecular Dynamics Simulations
|
We present calculations on the damping of a low-frequency adsorbate mode on a
metal surface, namely the frustrated translation of Na on Cu(100). For the
first time, vibrational lifetimes of excited adlayers are extracted from
non-equilibrium molecular dynamics calculations accounting for both the
phononic and the electronic dissipation channels. The relative contributions of
the two damping mechanisms, which we show to be additive, are found to disagree
with textbook predictions. A simple model based on separable harmonic and
anharmonic contributions is able to semi-quantitatively reproduce the
temperature dependence of the computed lifetimes.
|
1906.11776v1
|
2019-07-10
|
Formal expansions in stochastic model for wave turbulence 1: kinetic limit
|
We consider the damped/driver (modified) cubic NLS equation on a large torus
with a properly scaled forcing and dissipation, and decompose its solutions to
formal series in the amplitude. We study the second order truncation of this
series and prove that when the amplitude goes to zero and the torus' size goes
to infinity the energy spectrum of the truncated solutions becomes close to a
solution of the damped/driven wave kinetic equation. Next we discuss higher
order truncations of the series.
|
1907.04531v4
|
2019-07-22
|
Thresholds for low regularity solutions to wave equations with structural damping
|
We study the asymptotic behavior of solutions to wave equations with a
structural damping term \[ u_{tt}-\Delta u+\Delta^2 u_t=0, \qquad
u(0,x)=u_0(x), \,\,\, u_t(0,x)=u_1(x), \] in the whole space. New thresholds
are reported in this paper that indicate which of the diffusion wave property
and the non-diffusive structure dominates in low regularity cases. We develop
to that end the previous author's research in 2019 where they have proposed a
threshold that expresses whether the parabolic-like property or the wave-like
property strongly appears in the solution to some regularity-loss type
dissipative wave equation.
|
1907.09299v1
|
2019-08-03
|
Lindblad dynamics of the damped and forced quantum harmonic oscillator
|
The quantum dynamics of a damped and forced harmonic oscillator is
investigated in terms of a Lindblad master equation. Elementary algebraic
techniques are employed allowing for example to analyze the long time behavior,
i.e. the quantum limit cycle. The time evolution of various expectation values
is obtained in closed form as well as the entropy and the Husimi phase space
distribution. We also discuss the related description in terms of a
non-Hermitian Hamiltonian.
|
1908.01187v2
|
2019-08-07
|
Decay estimates for the linear damped wave equation on the Heisenberg group
|
This paper is devoted to the derivation of $L^2$ - $L^2$ decay estimates for
the solution of the homogeneous linear damped wave equation on the Heisenberg
group $\mathbf{H}_n$, for its time derivative and for its horizontal gradient.
Moreover, we consider the improvement of these estimates when further
$L^1(\mathbf{H}_n)$ regularity is required for the Cauchy data. Our approach
will rely strongly on the group Fourier transform of $\mathbf{H}_n$ and on the
properties of the Hermite functions that form a maximal orthonormal system for
$L^2(\mathbb{R}^n)$ of eigenfunctions of the harmonic oscillator.
|
1908.02657v1
|
2019-08-08
|
Critical exponent of Fujita-type for the semilinear damped wave equation on the Heisenberg group with power nonlinearity
|
In this paper, we consider the Cauchy problem for the semilinear damped wave
equation on the Heisenberg group with power nonlinearity. We prove that the
critical exponent is the Fujita exponent $p_{\mathrm{Fuj}}(\mathscr{Q}) = 1+2 /
\mathscr{Q}$, where $\mathscr{Q}$ is the homogeneous dimension of the
Heisenberg group. On the one hand, we will prove the global existence of small
data solutions for $p >p_{\mathrm{Fuj}}(\mathscr{Q})$ in an exponential
weighted energy space. On the other hand, a blow-up result for $1 < p \leq
p_{\mathrm{Fuj}}(\mathscr{Q})$ under certain integral sign assumptions for the
Cauchy data by using the test function method.
|
1908.02989v1
|
2019-09-01
|
Invariant measures for stochastic damped 2D Euler equations
|
We study the two-dimensional Euler equations, damped by a linear term and
driven by an additive noise. The existence of weak solutions has already been
studied; pathwise uniqueness is known for solutions that have vorticity in
$L^\infty$. In this paper, we prove the Markov property and then the existence
of an invariant measure in the space $L^\infty$ by means of a
Krylov-Bogoliubov's type method, working with the weak$\star$ and the bounded
weak$\star$ topologies in $L^\infty$.
|
1909.00424v2
|
2019-09-03
|
A blow-up result for semi-linear structurally damped $σ$-evolution equations
|
We would like to prove a blow-up result for semi-linear structurally damped
$\sigma$-evolution equations, where $\sigma \ge 1$ and $\delta\in [0,\sigma)$
are assumed to be any fractional numbers. To deal with the fractional Laplacian
operators $(-\Delta)^\sigma$ and $(-\Delta)^\delta$ as well-known non-local
operators, in general, it seems difficult to apply the standard test function
method directly. For this reason, in this paper we shall construct new test
functions to overcome this difficulty.
|
1909.01181v1
|
2019-09-09
|
Action Functional for a Particle with Damping
|
In this brief report we discuss the action functional of a particle with
damping, showing that it can be obtained from the dissipative equation of
motion through a modification which makes the new dissipative equation
invariant for time reversal symmetry. This action functional is exactly the
effective action of Caldeira-Leggett model but, in our approach, it is derived
without the assumption that the particle is weakly coupled to a bath of
infinite harmonic oscillators.
|
1909.03694v2
|
2019-09-11
|
Equilibrium radiation in a plasma medium with spatial and frequency dispersion
|
Examination of equilibrium radiation in plasma media shows that the spectral
energy distribution of such radiation is different from the Planck equilibrium
radiation. Using the approach of quantum electrodynamics the general relation
for the spectral energy density of equilibrium radiation in a system of charged
particles is found. The obtained result takes into account the influence of
plasma on equilibrium radiation through the explicit transverse dielectric
permittivity which takes into account spatial and frequency dispersion, as well
as the finite collisional damping. For the limiting case of an infinitesimal
damping the result coincides with the known expression.
|
1909.08056v1
|
2019-10-14
|
Blow-up of solutions to semilinear strongly damped wave equations with different nonlinear terms in an exterior domain
|
In this paper, we consider the initial boundary value problem in an exterior
domain for semilinear strongly damped wave equations with power nonlinear term
of the derivative-type $|u_t|^q$ or the mixed-type $|u|^p+|u_t|^q$, where
$p,q>1$. On one hand, employing the Banach fixed-point theorem we prove local
(in time) existence of mild solutions. On the other hand, under some conditions
for initial data and the exponents of power nonlinear terms, the blow-up
results are derived by applying the test function method.
|
1910.05981v1
|
2019-11-03
|
Linear Inviscid Damping in Sobolev and Gevrey Spaces
|
In a recent article Jia established linear inviscid damping in Gevrey
regularity for compactly supported Gevrey regular shear flows in a finite
channel, which is of great interest in view of existing nonlinear results. In
this article we provide an alternative very short proof of stability in Gevrey
regularity as a consequence of stability in high Sobolev regularity. Here, we
consider both the setting of a finite channel with compactly supported
perturbations and of an infinite channel without this restriction. Furthermore,
we consider the setting where perturbations vanish only of finite order.
|
1911.00880v1
|
2019-11-03
|
A global existence result for two-dimensional semilinear strongly damped wave equation with mixed nonlinearity in an exterior domain
|
We study two-dimensional semilinear strongly damped wave equation with mixed
nonlinearity $|u|^p+|u_t|^q$ in an exterior domain, where $p,q>1$. Assuming the
smallness of initial data in exponentially weighted spaces and some conditions
on powers of nonlinearity, we prove global (in time) existence of small data
energy solution with suitable higher regularity by using a weighted energy
method.
|
1911.00899v1
|
2019-11-05
|
Critical exponent for a weakly coupled system of semi-linear $σ$-evolution equations with frictional damping
|
We are interested in studying the Cauchy problem for a weakly coupled system
of semi-linear $\sigma$-evolution equations with frictional damping. The main
purpose of this paper is two-fold. We would like to not only prove the global
(in time) existence of small data energy solutions but also indicate the
blow-up result for Sobolev solutions when $\sigma$ is assumed to be any
fractional number.
|
1911.01946v1
|
2019-11-11
|
Existence and nonexistence of global solutions for a structurally damped wave system with power nonlinearities
|
Our interest itself of this paper is strongly inspired from an open problem
in the paper [1] published by D'Abbicco. In this article, we would like to
study the Cauchy problem for a weakly coupled system of semi-linear
structurally damped wave equations. Main goal is to find the threshold, which
classifies the global (in time) existence of small data solutions or the
nonexistence of global solutions under the growth condition of the
nonlinearities.
|
1911.04412v1
|
2019-11-15
|
Some $L^1$-$L^1$ estimates for solutions to visco-elastic damped $σ$-evolution models
|
This note is to conclude $L^1-L^1$ estimates for solutions to the following
Cauchy problem for visco-elastic damped $\sigma$-evolution models:
\begin{equation} \begin{cases} u_{tt}+ (-\Delta)^\sigma u+ (-\Delta)^\sigma u_t
= 0, &\quad x\in \mathbb{R}^n,\, t \ge 0, \\ u(0,x)= u_0(x),\quad
u_t(0,x)=u_1(x), &\quad x\in \mathbb{R}^n, \label{pt1.1} \end{cases}
\end{equation} where $\sigma> 1$, in all space dimensions $n\ge 1$.
|
1911.06563v1
|
2019-11-22
|
Long-time asymptotics for a coupled thermoelastic plate-membrane system
|
In this paper we consider a transmission problem for a system of a
thermoelastic plate with (or without) rotational inertia term coupled with a
membrane with different variants of damping for the plate and/or the membrane.
We prove well-posedness of the problem and higher regularity of the solution
and study the asymptotic behaviour of the solution, depending on the damping
and on the presence of the rotational term.
|
1911.10161v1
|
2019-11-28
|
Tikhonov regularization of a second order dynamical system with Hessian driven damping
|
We investigate the asymptotic properties of the trajectories generated by a
second-order dynamical system with Hessian driven damping and a Tikhonov
regularization term in connection with the minimization of a smooth convex
function in Hilbert spaces. We obtain fast convergence results for the function
values along the trajectories. The Tikhonov regularization term enables the
derivation of strong convergence results of the trajectory to the minimizer of
the objective function of minimum norm.
|
1911.12845v2
|
2019-12-15
|
Negative mobility, sliding and delocalization for stochastic networks
|
We consider prototype configurations for quasi-one-dimensional stochastic
networks that exhibit negative mobility, meaning that current decreases or even
reversed as the bias is increased. We then explore the implications of
disorder. In particular we ask whether lower and upper bias thresholds restrict
the possibility to witness non-zero current (sliding and anti-sliding
transitions respectively), and whether a delocalization effect manifest itself
(crossover from over-damped to under-damped relaxation). In the latter context
detailed analysis of the relaxation spectrum as a function of the bias is
provided for both on-chain and off-chain disorder.
|
1912.07059v2
|
2019-12-23
|
On a damped Szego equation (with an appendix in collaboration with Christian Klein)
|
We investigate how damping the lowest Fourier mode modifies the dynamics of
the cubic Szeg{\"o} equation. We show that there is a nonempty open subset of
initial data generating trajec-tories with high Sobolev norms tending to
infinity. In addition, we give a complete picture of this phenomenon on a
reduced phase space of dimension 6. An appendix is devoted to numerical
simulations supporting the generalisation of this picture to more general
initial data.
|
1912.10933v1
|
2020-01-29
|
The long time behavior and the rate of convergence of symplectic convex algorithms obtained via splitting discretizations of inertial damping systems
|
In this paper we propose new numerical algorithms in the setting of
unconstrained optimization problems and we study the rate of convergence in the
iterates of the objective function. Furthermore, our algorithms are based upon
splitting and symplectic methods and they preserve the energy properties of the
inherent continuous dynamical system that contains a Hessian perturbation. At
the same time, we show that Nesterov gradient method is equivalent to a
Lie-Trotter splitting applied to a Hessian driven damping system. Finally, some
numerical experiments are presented in order to validate the theoretical
results.
|
2001.10831v2
|
2020-02-05
|
Long-time asymptotics of the one-dimensional damped nonlinear Klein-Gordon equation
|
For the one-dimensional nonlinear damped Klein-Gordon equation \[
\partial_{t}^{2}u+2\alpha\partial_{t}u-\partial_{x}^{2}u+u-|u|^{p-1}u=0 \quad
\mbox{on $\mathbb{R}\times\mathbb{R}$,}\] with $\alpha>0$ and $p>2$, we prove
that any global finite energy solution either converges to $0$ or behaves
asymptotically as $t\to \infty$ as the sum of $K\geq 1$ decoupled solitary
waves. In the multi-soliton case $K\geq 2$, the solitary waves have alternate
signs and their distances are of order $\log t$.
|
2002.01826v1
|
2020-02-11
|
Distributional Solutions of the Damped Wave Equation
|
This work presents results on solutions of the one-dimensional damped wave
equation, also called telegrapher's equation, when the initial conditions are
general distributions, not only functions. We make a complete deduction of its
fundamental solutions, both for positive and negative times. To obtain them we
use only self-similarity arguments and distributional calculus, making no use
of Fourier or Laplace transforms. We next use these fundamental solutions to
prove both the existence and the uniqueness of solutions to the distributional
initial value problem. As applications we recover the semigroup property for
initial data in classical function spaces and also the probability distribution
function for a certain financial model of evolution of prices.
|
2002.04249v2
|
2020-02-13
|
Description of the wavevector dispersion of surface plasmon-phonon-polaritons
|
We reported here the results of the calculations of wavevector dispersion of
oscillations frequencies, $\omega'(k)$, and damping $\omega''(k)$ of the
surface plasmon phonon polaritons (\mbox{SPPhP}) for the heavy-doped GaN
sample. We showed that $\omega'(k)$- dependence consists of the three branches
with the specific anticrossing behavior due to the interaction of surface
plasmon polariton (SPP) with surface phonon polariton(SPhP). The strong
renormalization of the damping $\omega''(k)$ in the vicinity of the
anticrossing region was found. The obtained dispersions of the $\omega'(k)$ and
$\omega''(k)$ were applied for the analytical analysis of exact electrodynamic
simulation of the resonant behavior of the reflectivity spectrum of the n-GaN
grating.
|
2002.05473v1
|
2020-03-20
|
The Cauchy problem of the semilinear second order evolution equation with fractional Laplacian and damping
|
In the present paper, we prove time decay estimates of solutions in weighted
Sobolev spaces to the second order evolution equation with fractional Laplacian
and damping for data in Besov spaces. Our estimates generalize the estimates
obtained in the previous studies. The second aim of this article is to apply
these estimates to prove small data global well-posedness for the Cauchy
problem of the equation with power nonlinearities. Especially, the estimates
obtained in this paper enable us to treat more general conditions on the
nonlinearities and the spatial dimension than the results in the previous
studies.
|
2003.09239v1
|
2020-03-31
|
Time-Asymptotics of Physical Vacuum Free Boundaries for Compressible Inviscid Flows with Damping
|
In this paper, we prove the leading term of time-asymptotics of the moving
vacuum boundary for compressible inviscid flows with damping to be that for
Barenblatt self-similar solutions to the corresponding porous media equations
obtained by simplifying momentum equations via Darcy's law plus the possible
shift due to the movement of the center of mass, in the one-dimensional and
three-dimensional spherically symmetric motions, respectively. This gives a
complete description of the large time asymptotic behavior of solutions to the
corresponding vacuum free boundary problems. The results obtained in this paper
are the first ones concerning the large time asymptotics of physical vacuum
boundaries for compressible inviscid fluids, to the best of our knowledge.
|
2003.14072v2
|
2020-04-13
|
Landau damping for analytic and Gevrey data
|
In this paper, we give an elementary proof of the nonlinear Landau damping
for the Vlasov-Poisson system near Penrose stable equilibria on the torus
$\mathbb{T}^d \times \mathbb{R}^d$ that was first obtained by Mouhot and
Villani in \cite{MV} for analytic data and subsequently extended by Bedrossian,
Masmoudi, and Mouhot \cite{BMM} for Gevrey-$\gamma$ data,
$\gamma\in(\frac13,1]$. Our proof relies on simple pointwise resolvent
estimates and a standard nonlinear bootstrap analysis, using an ad-hoc family
of analytic and Gevrey-$\gamma$ norms.
|
2004.05979v3
|
2020-04-16
|
Strichartz estimates for mixed homogeneous surfaces in three dimensions
|
We obtain sharp mixed norm Strichartz estimates associated to mixed
homogeneous surfaces in $\mathbb{R}^3$. Both cases with and without a damping
factor are considered. In the case when a damping factor is considered our
results yield a wide generalization of a result of Carbery, Kenig, and Ziesler
[CKZ13]. The approach we use is to first classify all possible singularities
locally, after which one can tackle the problem by appropriately modifying the
methods from the paper of Ginibre and Velo [GV92], and by using the recently
developed methods by Ikromov and M\"uller [IM16].
|
2004.07751v1
|
2020-04-17
|
Critical exponent for semi-linear structurally damped wave equation of derivative type
|
Main purpose of this paper is to study the following semi-linear structurally
damped wave equation with nonlinearity of derivative type: $$u_{tt}- \Delta u+
\mu(-\Delta)^{\sigma/2} u_t= |u_t|^p,\quad u(0,x)= u_0(x),\quad
u_t(0,x)=u_1(x),$$ with $\mu>0$, $n\geq1$, $\sigma \in (0,2]$ and $p>1$. In
particular, we are going to prove the non-existence of global weak solutions by
using a new test function and suitable sign assumptions on the initial data in
both the subcritical case and the critical case.
|
2004.08486v2
|
2020-04-29
|
Exponential decay for damped Klein-Gordon equations on asymptotically cylindrical and conic manifolds
|
We study the decay of the global energy for the damped Klein-Gordon equation
on non-compact manifolds with finitely many cylindrical and subconic ends up to
bounded perturbation. We prove that under the Geometric Control Condition, the
decay is exponential, and that under the weaker Network Control Condition, the
decay is logarithmic, by developing the global Carleman estimate with multiple
weights.
|
2004.13894v2
|
2020-05-06
|
Zero-dimensional models for gravitational and scalar QED decoherence
|
We investigate the dynamics of two quantum mechanical oscillator system-bath
toy models obtained by truncating to zero spatial dimensions linearized gravity
coupled to a massive scalar field and scalar QED. The scalar-gravity toy model
maps onto the phase damped oscillator, while the scalar QED toy model
approximately maps onto an oscillator system subject to two-photon damping. The
toy models provide potentially useful insights into solving for open system
quantum dynamics relevant to the full scalar QED and weak gravitational field
systems, in particular operational probes of the decoherence for initial scalar
field system superposition states.
|
2005.02554v2
|
2020-05-16
|
On the asymptotic stability of wave equations coupled by velocities of anti-symmetric type
|
In this paper, we study the asymptotic stability of two wave equations
coupled by velocities of anti-symmetric type via only one damping. We adopt the
frequency domain method to prove that the system with smooth initial data is
logarithmically stable, provided that the coupling domain and the damping
domain intersect each other. Moreover, we show, by an example, that this
geometric assumption of the intersection is necessary for 1-D case.
|
2005.07977v2
|
2020-05-27
|
On the blow-up of solutions to semilinear damped wave equations with power nonlinearity in compact Lie groups
|
In this note, we prove a blow-up result for the semilinear damped wave
equation in a compact Lie group with power nonlinearity $|u|^p$ for any $p>1$,
under suitable integral sign assumptions for the initial data, by using an
iteration argument. A byproduct of this method is the upper bound estimate for
the lifespan of a local in time solution. As a preliminary result, a local (in
time) existence result is proved in the energy space via Fourier analysis on
compact Lie groups.
|
2005.13479v2
|
2020-06-13
|
On the well-posedness of the damped time-harmonic Galbrun equation and the equations of stellar oscillations
|
We study the time-harmonic Galbrun equation describing the propagation of
sound in the presence of a steady background flow. With additional rotational
and gravitational terms these equations are also fundamental in helio- and
asteroseismology as a model for stellar oscillations. For a simple damping
model we prove well-posedness of these equations, i.e. uniqueness, existence,
and stability of solutions under mild conditions on the parameters (essentially
subsonic flows). The main tool of our analysis is a generalized Helmholtz
decomposition.
|
2006.07658v1
|
2020-06-22
|
Prediction of short time qubit readout via measurement of the next quantum jump of a coupled damped driven harmonic oscillator
|
The dynamics of the next quantum jump for a qubit [two level system] coupled
to a readout resonator [damped driven harmonic oscillator] is calculated. A
quantum mechanical treatment of readout resonator reveals non exponential short
time behavior which could facilitate detection of the state of the qubit faster
than the resonator lifetime.
|
2006.11950v1
|
2020-07-08
|
The interplay of critical regularity of nonlinearities in a weakly coupled system of semi-linear damped wave equations
|
We would like to study a weakly coupled system of semi-linear classical
damped wave equations with moduli of continuity in nonlinearities whose powers
belong to the critical curve in the $p-q$ plane. The main goal of this paper is
to find out the sharp conditions of these moduli of continuity which classify
between global (in time) existence of small data solutions and finite time
blow-up of solutions.
|
2007.04157v1
|
2020-07-09
|
Semi-uniform stability of operator semigroups and energy decay of damped waves
|
Only in the last fifteen years or so has the notion of semi-uniform
stability, which lies between exponential stability and strong stability,
become part of the asymptotic theory of $C_0$-semigroups. It now lies at the
very heart of modern semigroup theory. After briefly reviewing the notions of
exponential and strong stability, we present an overview of some of the best
known (and often optimal) abstract results on semi-uniform stability. We go on
to indicate briefly how these results can be applied to obtain (sometimes
optimal) rates of energy decay for certain damped second-order Cauchy problems.
|
2007.04711v1
|
2020-07-10
|
Quasi-periodic travelling waves for a class of damped beams on rectangular tori
|
This article concerns a class of beam equations with damping on rectangular
tori. When the generators satisfy certain relationship, by excluding some value
of two model parameters, we prove that such models admit small amplitude
quasi-periodic travelling wave solutions with two frequencies, which are
continuations of two rotating wave solutions with one frequency. This result
holds not only for an isotropic torus, but also for an anisotropic torus. The
proof is mainly based on a Lyapunov--Schmidt reduction together with the
implicit function theorem.
|
2007.05154v1
|
2020-07-24
|
A Framework to Control Inter-Area Oscillations with Local Measurement
|
Inter-area oscillations in power system limit of power transfer capability
though tie-lines. For stable operation, wide-area power system stabilizers are
deployed to provide sufficient damping. However, as the feedback is through a
communication network, it brings challenges such as additional communication
layer and cybersecurity issues. To address this, a framework for synthesizing
remote signal from local measurement as feedback in the wide-area power system
stabilizer is proposed. The remote signal is synthesized using different
variants of observers in a case study of two-area benchmark system. The
proposed framework can improve the damping of inter-area oscillations for
static output feedback controller. The presented framework should help to
design attack-resilient controller design in smart grid.
|
2007.12426v1
|
2020-07-24
|
Convergence Rates of Inertial Primal-Dual Dynamical Methods for Separable Convex Optimization Problems
|
In this paper, we propose a second-order continuous primal-dual dynamical
system with time-dependent positive damping terms for a separable convex
optimization problem with linear equality constraints. By the Lyapunov function
approach, we investigate asymptotic properties of the proposed dynamical system
as the time $t\to+\infty$. The convergence rates are derived for different
choices of the damping coefficients. We also show that the obtained results are
robust under external perturbations.
|
2007.12428v1
|
2020-08-17
|
Dynamics of spatially indistinguishable particles and entanglement protection
|
We provide a general framework which allows one to obtain the dynamics of $N$
noninteracting spatially indistinguishable particles locally coupled to
separated environments. The approach is universal, being valid for both bosons
and fermions and for any type of system-environment interaction. It is then
applied to study the dynamics of two identical qubits under paradigmatic
Markovian noises, such as phase damping, depolarizing and amplitude damping. We
find that spatial indistinguishability of identical qubits is a controllable
intrinsic property of the system which protects quantum entanglement against
detrimental noise.
|
2008.07471v1
|
2020-09-02
|
Discriminating qubit amplitude damping channels
|
We address the issue of the discrimination between two-qubit amplitude
damping channels by exploring several strategies. For the single-shot, we show
that the excited state does not always give the optimal input, and that side
entanglement assistance has limited benefit. On the contrary, feedback
assistance from the environment is more beneficial. For the two-shot, we prove
the in-utility of entangled inputs. Then focusing on individual (local)
measurements, we find the optimal adaptive strategy.
|
2009.01000v3
|
2020-09-03
|
Asymptotic behavior of 2D stably stratified fluids with a damping term in the velocity equation
|
This article is concerned with the asymptotic behavior of the two-dimensional
inviscid Boussinesq equations with a damping term in the velocity equation.
Precisely, we provide the time-decay rates of the smooth solutions to that
system. The key ingredient is a careful analysis of the Green kernel of the
linearized problem in Fourier space, combined with bilinear estimates and
interpolation inequalities for handling the nonlinearity.
|
2009.01578v2
|
2020-08-05
|
The perturbational stability of the Schr$\ddot{o}$dinger equation
|
By using the Wigner transform, it is shown that the nonlinear
Schr$\ddot{\textmd{o}}$dinger equation can be described, in phase space, by a
kinetic theory similar to the Vlasov equation which is used for describing a
classical collisionless plasma. In this paper we mainly show Landau damping in
the quantum sense, namely,quantum Landau damping exists for the Wigner-Poisson
system. At the same time, we also prove the existence and the stability of the
nonlinear Schr$\ddot{\textmd{o}}$dinger equation under the quantum stability
assumption.
|
2009.09855v1
|
2020-10-12
|
Long time behavior of solutions for a damped Benjamin-Ono equation
|
We consider the Benjamin-Ono equation on the torus with an additional damping
term on the smallest Fourier modes (cos and sin). We first prove global
well-posedness of this equation in $L^2_{r,0}(\mathbb{T})$. Then, we describe
the weak limit points of the trajectories in $L^2_{r,0}(\mathbb{T})$ when time
goes to infinity, and show that these weak limit points are strong limit
points. Finally, we prove the boundedness of higher-order Sobolev norms for
this equation. Our key tool is the Birkhoff map for the Benjamin-Ono equation,
that we use as an adapted nonlinear Fourier transform.
|
2010.05520v1
|
2020-10-21
|
Initial boundary value problem for a strongly damped wave equation with a general nonlinearity
|
In this paper, a strongly damped semilinear wave equation with a general
nonlinearity is considered. With the help of a newly constructed auxiliary
functional and the concavity argument, a general finite time blow-up criterion
is established for this problem. Furthermore, the lifespan of the weak solution
is estimated from both above and below. This partially extends some results
obtained in recent literatures and sheds some light on the similar effect of
power type nonlinearity and logarithmic nonlinearity on finite time blow-up of
solutions to such problems.
|
2010.10696v1
|
2020-10-21
|
MRI Image Recovery using Damped Denoising Vector AMP
|
Motivated by image recovery in magnetic resonance imaging (MRI), we propose a
new approach to solving linear inverse problems based on iteratively calling a
deep neural-network, sometimes referred to as plug-and-play recovery. Our
approach is based on the vector approximate message passing (VAMP) algorithm,
which is known for mean-squared error (MSE)-optimal recovery under certain
conditions. The forward operator in MRI, however, does not satisfy these
conditions, and thus we design new damping and initialization schemes to help
VAMP. The resulting DD-VAMP++ algorithm is shown to outperform existing
algorithms in convergence speed and accuracy when recovering images from the
fastMRI database for the practical case of Cartesian sampling.
|
2010.11321v1
|
2020-11-05
|
Mathematical modelling of an unstable bent flow using the selective frequency damping method
|
The selective frequency damping method was applied to a bent flow. The method
was used in an adaptive formulation. The most dangerous frequency was
determined by solving an eigenvalue problem. It was found that one of the
patterns, steady-state or pulsating, may exist at some relatively high Reynolds
numbers. The periodic flow occurs due to the instability of the steady-state
flow. This numerical method is easy to use but requires a great deal of time
for calculations.
|
2011.02646v1
|
2020-11-04
|
The "Dark disk" model in the light of DAMPE experiment
|
There are a lot of models considering the Dark Matter (DM) to be the origin
of cosmic ray (CR) positron excess. However, they face an obstacle in the form
of gamma-rays. Simple DM models tend to overproduce gamma-rays, leading to
contradiction with isotropic gamma-ray background (IGRB). The <<dark disk>>
model has been proposed to alleviate this contradiction. This work considers
results of DAMPE experiment in the framework of the disk model. It is obtained
that such a framework allows improving data fit considerably.
|
2011.04425v2
|
2020-12-15
|
On the stability of Bresse system with one discontinuous local internal Kelvin-Voigt damping on the axial force
|
In this paper, we investigate the stabilization of a linear Bresse system
with one discontinuous local internal viscoelastic damping of Kelvin-Voigt type
acting on the axial force, under fully Dirichlet boundary conditions. First,
using a general criteria of Arendt-Batty, we prove the strong stability of our
system. Finally, using a frequency domain approach combined with the multiplier
method, we prove that the energy of our system decays polynomially with
different rates.
|
2012.08219v1
|
2021-01-16
|
Convergence of non-autonomous attractors for subquintic weakly damped wave equation
|
We study the non-autonomous weakly damped wave equation with subquintic
growth condition on the nonlinearity. Our main focus is the class of
Shatah--Struwe solutions, which satisfy the Strichartz estimates and are
coincide with the class of solutions obtained by the Galerkin method. For this
class we show the existence and smoothness of pullback, uniform, and cocycle
attractors and the relations between them. We also prove that these
non-autonomous attractors converge upper-semicontinuously to the global
attractor for the limit autonomous problem if the time-dependent nonlinearity
tends to time independent function in an appropriate way.
|
2101.06523v1
|
2021-01-20
|
A Damped Newton Algorithm for Generated Jacobian Equations
|
Generated Jacobian Equations have been introduced by Trudinger [Disc. cont.
dyn. sys (2014), pp. 1663-1681] as a generalization of Monge-Amp{\`e}re
equations arising in optimal transport. In this paper, we introduce and study a
damped Newton algorithm for solving these equations in the semi-discrete
setting, meaning that one of the two measures involved in the problem is
finitely supported and the other one is absolutely continuous. We also present
a numerical application of this algorithm to the near-field parallel refractor
problem arising in non-imaging problems.
|
2101.08080v1
|
2021-02-14
|
Suppression of singularities of solutions of the Euler-Poisson system with density-dependent damping
|
We find a sharp condition on the density-dependent coefficient of damping of
a one-dimensional repulsive Euler-Poisson system, which makes it possible to
suppress the formation of singularities in the solution of the Cauchy problem
with arbitrary smooth data. In the context of plasma physics, this means the
possibility of suppressing the breakdown of arbitrary oscillations of cold
plasma.
|
2102.07176v2
|
2021-02-15
|
Piezoelectric beam with magnetic effect, time-varying delay and time-varying weights
|
The main result of this work is to obtain the exponential decay of the
solutions of a piezoelectric beam model with magnetic effect and delay term.
The dampings are inserted into the equation of longitudinal displacement. The
terms of damping, whose weight associated with them varies over time, are of
the friction type, and one of them has delay. This work will also address the
issue of existence and uniqueness of solution for the model.
|
2102.07538v1
|
2021-02-23
|
Effects of ground-state correlations on damping of giant dipole resonaces in $LS$ closed shell nuclei
|
The effects of ground-state correlations on the damping of isovector giant
dipole resonances in $LS$ closed shell nuclei $^{16}$O and $^{40}$Ca are
studied using extended random-phase-approximation (RPA) approaches derived from
the time-dependent density-matrix theory. It is pointed out that unconventional
two-body amplitudes of one particle--three hole and three particle--one hole
types which are neglected in most extended RPA theories play an important role
in the fragmentation of isovector dipole strength.
|
2102.11505v2
|
2021-02-28
|
The influence of the physical coefficients of a Bresse system with one singular local viscous damping in the longitudinal displacement on its stabilization
|
In this paper, we investigate the stabilization of a linear Bresse system
with one singular local frictional damping acting in the longitudinal
displacement, under fully Dirichlet boundary conditions. First, we prove the
strong stability of our system. Next, using a frequency domain approach
combined with the multiplier method, we establish the exponential stability of
the solution if and only if the three waves have the same speed of propagation.
On the contrary, we prove that the energy of our system decays polynomially
with rates $t^{-1}$ or $t^{-\frac{1}{2}}$.
|
2103.00628v2
|
2021-03-01
|
On a damped nonlinear beam equation
|
In this note we analyze the large time behavior of solutions to an
initial/boundary problem involving a damped nonlinear beam equation. We show
that under physically realistic conditions on the nonlinear terms in the
equation of motion the energy is a decreasing function of time and solutions
converge to a stationary solution with respect to a desirable norm.
|
2103.00969v3
|
2021-03-05
|
Universal spin wave damping in magnetic Weyl semimetals
|
We analyze the decay of spin waves into Stoner excitations in magnetic Weyl
semimetals. The lifetime of a mode is found to have a universal dependence on
its frequency and momentum, and on a few parameters that characterize the
relativistic Weyl spectrum. At the same time, Gilbert damping by Weyl electrons
is absent. The decay rate of spin waves is calculated perturbatively using the
s-d model of itinerant Weyl or Dirac electrons coupled to local moments. We
show that many details of the Weyl spectrum, such as the momentum-space
locations, dispersions and sizes of the Weyl Fermi pockets, can be deduced
indirectly by probing the spin waves of local moments using inelastic neutron
scattering.
|
2103.03885v1
|
2021-03-23
|
Fast convergence of dynamical ADMM via time scaling of damped inertial dynamics
|
In this paper, we propose in a Hilbertian setting a second-order
time-continuous dynamic system with fast convergence guarantees to solve
structured convex minimization problems with an affine constraint. The system
is associated with the augmented Lagrangian formulation of the minimization
problem. The corresponding dynamics brings into play three general time-varying
parameters, each with specific properties, and which are respectively
associated with viscous damping, extrapolation and temporal scaling. By
appropriately adjusting these parameters, we develop a Lyapunov analysis which
provides fast convergence properties of the values and of the feasibility gap.
These results will naturally pave the way for developing corresponding
accelerated ADMM algorithms, obtained by temporal discretization.
|
2103.12675v1
|
2021-03-29
|
Comparison between the Cauchy problem and the scattering problem for the Landau damping in the Vlasov-HMF equation
|
We analyze the analytic Landau damping problem for the Vlasov-HMF equation,
by fixing the asymptotic behavior of the solution. We use a new method for this
"scattering problem", closer to the one used for the Cauchy problem. In this
way we are able to compare the two results, emphasizing the different influence
of the plasma echoes in the two approaches. In particular, we prove a
non-perturbative result for the scattering problem.
|
2103.15932v2
|
2021-04-06
|
Realising Einstein's mirror: Optomechanical damping with a thermal photon gas
|
In 1909 Einstein described the thermalization of a mirror within a blackbody
cavity by collisions with thermal photons. While the time to thermalize the
motion of even a microscale or nanoscale object is so long that it is not
feasible, we show that it is using the high intensity light from an amplified
thermal light source with a well-defined chemical potential. We predict damping
of the center-of mass motion due to this effect on times scales of seconds for
small optomechanical systems, such as levitated nanoparticles, allowing
experimental observation.
|
2104.02708v2
|
2021-04-12
|
Fractional time stepping and adjoint based gradient computation in an inverse problem for a fractionally damped wave equation
|
In this paper we consider the inverse problem of identifying the initial data
in a fractionally damped wave equation from time trace measurements on a
surface, as relevant in photoacoustic or thermoacoustic tomography. We derive
and analyze a time stepping method for the numerical solution of the
corresponding forward problem. Moreover, to efficiently obtain reconstructions
by minimizing a Tikhonov regularization functional (or alternatively, by
computing the MAP estimator in a Bayesian approach), we develop an adjoint
based scheme for gradient computation. Numerical reconstructions in two space
dimensions illustrate the performance of the devised methods.
|
2104.05577v1
|
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