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2014-02-25
Du-Hwang Characteristic Area: Catch-22
The paper is devoted to description of two interconnected mistakes generated by the gap in the Du and Hwang approach to Gilbert-Pollack Steiner ratio conjecture.
1402.6079v1
2016-06-01
Existence of arbitrarily smooth solutions of the LLG equation in 3D with natural boundary conditions
We prove that the Landau-Lifshitz-Gilbert equation in three space dimensions with homogeneous Neumann boundary conditions admits arbitrarily smooth solutions, given that the initial data is sufficiently close to a constant function.
1606.00086v1
2018-10-28
Asymptotic Gilbert-Varshamov bound on Frequency Hopping Sequences
Given a $q$-ary frequency hopping sequence set of length $n$ and size $M$ with Hamming correlation $H$, one can obtain a $q$-ary (nonlinear) cyclic code of length $n$ and size $nM$ with Hamming distance $n-H$. Thus, every upper bound on the size of a code from coding theory gives an upper bound on the size of a frequen...
1810.11757v2
2020-05-26
Reidemeister Moves in Gauss Diagrams
We provide a simple algorithm for recognizing and performing Reidemeister moves in a Gauss diagram.
2005.12957v1
2021-05-26
Lee Weight for Nonbinary Quantum Error Correction
We propose the quantum Lee weight for quantum errors, provide a Gilbert-Varshamov type bound, and a code construction for the proposed weight.
2105.12354v1
2021-09-19
Compactness of isospectral conformal Finslerian metrics set on a 3-manifold
Let F be a Finslerian metric on an n-dimensional closed manifold M. In this work, we study problems about compactness of isospectral sets of conformal Finslerian metrics when n=3.
2110.06338v2
2001-05-31
Lower bound for the quantum capacity of a discrete memoryless quantum channel
We generalize the random coding argument of stabilizer codes and derive a lower bound on the quantum capacity of an arbitrary discrete memoryless quantum channel. For the depolarizing channel, our lower bound coincides with that obtained by Bennett et al. We also slightly improve the quantum Gilbert-Varshamov bound for...
0105151v4
2007-08-30
Asymptotic improvement of the Gilbert-Varshamov bound for linear codes
The Gilbert-Varshamov bound states that the maximum size A_2(n,d) of a binary code of length n and minimum distance d satisfies A_2(n,d) >= 2^n/V(n,d-1) where V(n,d) stands for the volume of a Hamming ball of radius d. Recently Jiang and Vardy showed that for binary non-linear codes this bound can be improved to A_2(n,...
0708.4164v1
2007-09-26
Finite Element Formalism for Micromagnetism
The aim of this work is to present the details of the finite element approach we developed for solving the Landau-Lifschitz-Gilbert equations in order to be able to treat problems involving complex geometries. There are several possibilities to solve the complex Landau-Lifschitz-Gilbert equations numerically. Our metho...
0709.4153v1
2009-05-07
Heat transport in stochastic energy exchange models of locally confined hard spheres
We study heat transport in a class of stochastic energy exchange systems that characterize the interactions of networks of locally trapped hard spheres under the assumption that neighbouring particles undergo rare binary collisions. Our results provide an extension to three-dimensional dynamics of previous ones applyin...
0905.1051v1
2011-08-15
Hydrodynamics of self-alignment interactions with precession and derivation of the Landau-Lifschitz-Gilbert equation
We consider a kinetic model of self-propelled particles with alignment interaction and with precession about the alignment direction. We derive a hydrodynamic system for the local density and velocity orientation of the particles. The system consists of the conservative equation for the local density and a non-conserva...
1108.2951v1
2011-09-30
Magnetization Dynamics, Gyromagnetic Relation, and Inertial Effects
The gyromagnetic relation - i.e. the proportionality between the angular momentum $\vec L$ (defined by an inertial tensor) and the magnetization $\vec M$ - is evidence of the intimate connections between the magnetic properties and the inertial properties of ferromagnetic bodies. However, inertia is absent from the dyn...
1109.6782v1
2012-08-28
Decomposition of modified Landau-Lifshitz-Gilbert equation and corresponding analytic solutions
The Suzuki-Trotter decomposition in general allows one to divide the equation of motion of a dynamical system into smaller parts whose integration are easier than the original equation. In this study, we first rewrite by employing feasible approximations the modified Landau-Lifshitz-Gilbert equation for localized spins...
1208.5545v1
2013-11-20
Asymptotic Improvement of the Gilbert-Varshamov Bound on the Size of Permutation Codes
Given positive integers $n$ and $d$, let $M(n,d)$ denote the maximum size of a permutation code of length $n$ and minimum Hamming distance $d$. The Gilbert-Varshamov bound asserts that $M(n,d) \geq n!/V(n,d-1)$ where $V(n,d)$ is the volume of a Hamming sphere of radius $d$ in $\S_n$. Recently, Gao, Yang, and Ge showe...
1311.4925v1
2016-11-21
On the List-Decodability of Random Self-Orthogonal Codes
In 2011, Guruswami-H{\aa}stad-Kopparty \cite{Gru} showed that the list-decodability of random linear codes is as good as that of general random codes. In the present paper, we further strengthen the result by showing that the list-decodability of random {\it Euclidean self-orthogonal} codes is as good as that of genera...
1611.06673v1
2017-11-29
Linear second-order IMEX-type integrator for the (eddy current) Landau-Lifshitz-Gilbert equation
Combining ideas from [Alouges et al. (Numer. Math., 128, 2014)] and [Praetorius et al. (Comput. Math. Appl., 2017)], we propose a numerical algorithm for the integration of the nonlinear and time-dependent Landau-Lifshitz-Gilbert (LLG) equation which is unconditionally convergent, formally (almost) second-order in time...
1711.10715v1
2017-12-28
Subquadratic time encodable codes beating the Gilbert-Varshamov bound
We construct explicit algebraic geometry codes built from the Garcia-Stichtenoth function field tower beating the Gilbert-Varshamov bound for alphabet sizes at least 192. Messages are identied with functions in certain Riemann-Roch spaces associated with divisors supported on multiple places. Encoding amounts to evalua...
1712.10052v2
2018-11-15
Hilbert-Schmidt distance and entanglement witnessing
Gilbert proposed an algorithm for bounding the distance between a given point and a convex set. In this article we apply the Gilbert's algorithm to get an upper bound on the Hilbert-Schmidt distance between a given state and the set of separable states. While Hilbert Schmidt Distance does not form a proper entanglement...
1811.06599v3
2020-02-13
Age of Information with Gilbert-Elliot Servers and Samplers
We study age of information in a status updating system that consists of a single sampler, i.e., source node, that sends time-sensitive status updates to a single monitor node through a server node. We first consider a Gilbert-Elliot service profile at the server node. In this model, service times at the server node fo...
2002.05711v1
2005-08-26
Damping of MHD turbulence in Solar Flares
(Abridged) We describe the cascade of plasma waves or turbulence injected, presumably by reconnection, at scales comparable to the size of a solar flare loop to scales comparable to particle gyroradii, and evaluate their damping by various mechanisms. We show that the classical viscous damping is unimportant for magnet...
0508567v1
2011-07-27
Constraint damping for the Z4c formulation of general relativity
One possibility for avoiding constraint violation in numerical relativity simulations adopting free-evolution schemes is to modify the continuum evolution equations so that constraint violations are damped away. Gundlach et. al. demonstrated that such a scheme damps low amplitude, high frequency constraint violating mo...
1107.5539v2
1999-11-24
Damped Lyman alpha absorber and the faint end of the galaxy luminosity function at high redshift
We combine predictions for several hierarchical cosmogonies with observational evidence on damped Lyman alpha systems to establish a correspondence between the high redshift galaxy population and the properties of damped Lyman alpha systems. We assume that high redshift galaxies and damped Lyman alpha systems are hoste...
9911447v1
2003-03-13
An explicit unconditionally stable numerical method for solving damped nonlinear Schrödinger equations with a focusing nonlinearity
This paper introduces an extension of the time-splitting sine-spectral (TSSP) method for solving damped focusing nonlinear Schr\"{o}dinger equations (NLS). The method is explicit, unconditionally stable and time transversal invariant. Moreover, it preserves the exact decay rate for the normalization of the wave functio...
0303158v1
2004-11-03
Quantum probability applied to the damped harmonic oscillator
In this introductory course we sketch the framework of quantum probability in order to discuss open quantum systems, in particular the damped harmonic oscillator.
0411024v1
2006-11-23
Path integrals and wavepacket evolution for damped mechanical systems
Damped mechanical systems with various forms of damping are quantized using the path integral formalism. In particular, we obtain the path integral kernel for the linearly damped harmonic oscillator and a particle in a uniform gravitational field with linearly or quadratically damped motion. In each case, we study the ...
0611239v1
2007-07-05
Damping of bulk excitations over an elongated BEC - the role of radial modes
We report the measurement of Beliaev damping of bulk excitations in cigar shaped Bose Einstein condensates of atomic vapor. By using post selection, excitation line shapes of the total population are compared with those of the undamped excitations. We find that the damping depends on the initial excitation energy of th...
0707.0776v1
2008-09-22
Damping in 2D and 3D dilute Bose gases
Damping in 2D and 3D dilute gases is investigated using both the hydrodynamical approach and the Hartree-Fock-Bogoliubov (HFB) approximation . We found that the both methods are good for the Beliaev damping at zero temperature and Landau damping at very low temperature, however, at high temperature, the hydrodynamical ...
0809.3632v3
2008-12-08
Landau Damping and Alfven Eigenmodes of Neutron Star Torsion Oscillations
Torsion oscillations of the neutron star crust are Landau damped by the Alfven continuum in the bulk. For strong magnetic fields (in magnetars), undamped Alfven eigenmodes appear.
0812.1570v1
2010-09-24
Spatial Damping of Propagating Kink Waves in Prominence Threads
Transverse oscillations and propagating waves are frequently observed in threads of solar prominences/filaments and have been interpreted as kink magnetohydrodynamic (MHD) modes. We investigate the spatial damping of propagating kink MHD waves in transversely nonuniform and partially ionized prominence threads. Resonan...
1009.4871v1
2012-08-01
Artificial Neural Network Based Prediction of Optimal Pseudo-Damping and Meta-Damping in Oscillatory Fractional Order Dynamical Systems
This paper investigates typical behaviors like damped oscillations in fractional order (FO) dynamical systems. Such response occurs due to the presence of, what is conceived as, pseudo-damping and meta-damping in some special class of FO systems. Here, approximation of such damped oscillation in FO systems with the con...
1208.0318v1
2012-08-27
Optimization of the damped quantum search
The damped quantum search proposed in [A. Mizel, Phys. Rev. Lett., 102 150501 (2009)] was analyzed by calculating the highest possible probability of finding the target state in each iteration. A new damping parameter that depends on the number of iterations was obtained, this was compared to the critical damping param...
1208.5475v1
2013-04-03
Damping the zero-point energy of a harmonic oscillator
The physics of quantum electromagnetism in an absorbing medium is that of a field of damped harmonic oscillators. Yet until recently the damped harmonic oscillator was not treated with the same kind of formalism used to describe quantum electrodynamics in a arbitrary medium. Here we use the techniques of macroscopic QE...
1304.0977v2
2015-05-28
Damping factors for head-tail modes at strong space charge
This paper suggests how feedback and Landau damping can be taken into account for transverse oscillations of bunched beam at strong space charge.
1505.07704v1
2015-06-18
Damping of MHD turbulence in partially ionized plasma: implications for cosmic ray propagation
We study the damping from neutral-ion collisions of both incompressible and compressible magnetohydrodynamic (MHD) turbulence in partially ionized medium. We start from the linear analysis of MHD waves applying both single-fluid and two-fluid treatments. The damping rates derived from the linear analysis are then used ...
1506.05585v1
2016-02-04
Damping Evaluation for Free Vibration of Spherical Structures in Elastodynamic-Acoustic Interaction
This paper discusses the free vibration of elastic spherical structures in the presence of an externally unbounded acoustic medium. In this vibration, damping associated with the radiation of energy from the confined solid medium to the surrounding acoustic medium is observed. Evaluating the coupled system response (so...
1604.06738v1
2017-09-05
Enhancement of space-charge induced damping due to reactive impedances for head-tail modes
Landau damping of head-tail modes in bunches due to spreads in the tune shift can be a deciding factor for beam stability. We demonstrate that the coherent tune shifts due to reactive impedances can enhance the space-charge induced damping and change the stability thresholds (here, a reactive impedance implies the imag...
1709.01425v1
2018-05-21
Critical damping in nonviscously damped linear systems
In structural dynamics, energy dissipative mechanisms with non-viscous damping are characterized by their dependence on the time-history of the response velocity, mathematically represented by convolution integrals involving hereditary functions. Combination of damping parameters in the dissipative model can lead the s...
1805.08022v1
2018-11-01
Hereditary effects of exponentially damped oscillators with past histories
Hereditary effects of exponentially damped oscillators with past histories are considered in this paper. Nonviscously damped oscillators involve hereditary damping forces which depend on time-histories of vibrating motions via convolution integrals over exponentially decaying functions. As a result, this kind of oscill...
1811.00216v1
2019-08-01
The Temperature-dependent Damping of Propagating Slow Magnetoacoustic Waves
The rapid damping of slow magnetoacoustic waves in the solar corona has been extensively studied in previous years. Most studies suggest that thermal conduction is a dominant contributor to this damping, albeit with a few exceptions. Employing extreme-ultraviolet (EUV) imaging data from SDO/AIA, we measure the damping ...
1908.00384v1
2019-10-14
Decay rates for the damped wave equation with finite regularity damping
Decay rates for the energy of solutions of the damped wave equation on the torus are studied. In particular, damping invariant in one direction and equal to a sum of squares of nonnegative functions with a particular number of derivatives of regularity is considered. For such damping energy decays at rate $1/t^{2/3}$. ...
1910.06372v3
2022-07-01
Seismic Response of Yielding Structures Coupled to Rocking Walls with Supplemental Damping
Given that the coupling of a framing structure to a strong, rocking wall enforces a first-mode response, this paper investigates the dynamic response of a yielding single-degree-of-freedom oscillator coupled to a rocking wall with supplemental damping (hysteretic or linear viscous) along its sides. The full nonlinear e...
2207.00641v1
2023-03-08
Material-Geometry Interplay in Damping of Biomimetic Scale Beams
Biomimetic scale-covered substrates are architected meta-structures exhibiting fascinating emergent nonlinearities via the geometry of collective scales contacts. In spite of much progress in understanding their elastic nonlinearity, their dissipative behavior arising from scales sliding is relatively uninvestigated in...
2303.04920v1
2023-04-11
A comparison of 7 Tesla MR spectroscopic imaging and 3 Tesla MR fingerprinting for tumor localization in glioma patients
This paper investigates the correlation between magnetic resonance spectroscopic imaging (MRSI) and magnetic resonance fingerprinting (MRF) in glioma patients by comparing neuro-oncological markers obtained from MRSI to T1/T2 maps from MRF. Data from 12 consenting patients with gliomas were analyzed by defining hotsp...
2304.05254v1
1998-03-28
Landau damping and the echo effect in a confined Bose-Einstein condensate
Low energy collective mode of a confined Bose-Einstein condensate should demonstrate the echo effect in the regime of Landau damping. This echo is a signature of reversible nature of Landau damping. General expression for the echo profile is derived in the limit of small amplitudes of the external pulses. Several unive...
9803351v1
2000-07-10
Dephasing of Electrons on Helium by Collisions with Gas Atoms
The damping of quantum effects in the transport properties of electrons deposited on a surface of liquid helium is studied. It is found that due to vertical motion of the helium vapour atoms the interference of paths of duration $t$ is damped by a factor $\exp - (t/\tau_v)^3$. An expression is derived for the weak-loca...
0007160v1
1997-10-07
Damping rate of plasmons and photons in a degenerate nonrelativistic plasma
A calculation is presented of the plasmon and photon damping rates in a dense nonrelativistic plasma at zero temperature, following the resummation program of Braaten-Pisarski. At small soft momentum $k$, the damping is dominated by $3 \to 2$ scattering processes corresponding to double longitudinal Landau damping. The...
9710260v1
2002-12-16
Influence of damping on the vanishing of the electro-optic effect in chiral isotropic media
Using first principles, it is demonstrated that radiative damping alone cannot lead to a nonvanishing electro-optic effect in a chiral isotropic medium. This conclusion is in contrast with that obtained by a calculation in which damping effects are included using the standard phenomenological model. We show that these ...
0212089v1
2005-08-28
Simultaneous amplitude and phase damping of a kind of Gaussian states and their separability
We give out the time evolution solution of simultaneous amplitude and phase damping for any continuous variable state. For the simultaneous amplitude and phase damping of a wide class of two- mode entangled Gaussian states, two analytical conditions of the separability are given. One is the sufficient condition of sepa...
0508209v2
2007-05-14
Identification of the dominant precession damping mechanism in Fe, Co, and Ni by first-principles calculations
The Landau-Lifshitz equation reliably describes magnetization dynamics using a phenomenological treatment of damping. This paper presents first-principles calculations of the damping parameters for Fe, Co, and Ni that quantitatively agree with existing ferromagnetic resonance measurements. This agreement establishes th...
0705.1990v1
2007-08-28
Ising Dynamics with Damping
We show for the Ising model that is possible construct a discrete time stochastic model analogous to the Langevin equation that incorporates an arbitrary amount of damping. It is shown to give the correct equilibrium statistics and is then used to investigate nonequilibrium phenomena, in particular, magnetic avalanches...
0708.3855v1
2008-02-08
On the scaling of the damping time for resonantly damped oscillations in coronal loops
There is not as yet full agreement on the mechanism that causes the rapid damping of the oscillations observed by TRACE in coronal loops. It has been suggested that the variation of the observed values of the damping time as function of the corresponding observed values of the period contains information on the possibl...
0802.1143v1
2008-10-02
Critically damped quantum search
Although measurement and unitary processes can accomplish any quantum evolution in principle, thinking in terms of dissipation and damping can be powerful. We propose a modification of Grover's algorithm in which the idea of damping plays a natural role. Remarkably, we have found that there is a critical damping value ...
0810.0470v1
2009-07-01
Modal approximations to damped linear systems
We consider a finite dimensional damped second order system and obtain spectral inclusion theorems for the related quadratic eigenvalue problem. The inclusion sets are the 'quasi Cassini ovals' which may greatly outperform standard Gershgorin circles. As the unperturbed system we take a modally damped part of the syste...
0907.0167v1
2010-01-14
Multi-Error-Correcting Amplitude Damping Codes
We construct new families of multi-error-correcting quantum codes for the amplitude damping channel. Our key observation is that, with proper encoding, two uses of the amplitude damping channel simulate a quantum erasure channel. This allows us to use concatenated codes with quantum erasure-correcting codes as outer co...
1001.2356v1
2011-09-05
Spectral theory of damped quantum chaotic systems
We investigate the spectral distribution of the damped wave equation on a compact Riemannian manifold, especially in the case of a metric of negative curvature, for which the geodesic flow is Anosov. The main application is to obtain conditions (in terms of the geodesic flow on $X$ and the damping function) for which t...
1109.0930v1
2012-06-07
From resolvent estimates to damped waves
In this paper we show how to obtain decay estimates for the damped wave equation on a compact manifold without geometric control via knowledge of the dynamics near the un-damped set. We show that if replacing the damping term with a higher-order \emph{complex absorbing potential} gives an operator enjoying polynomial r...
1206.1565v1
2012-12-03
Inviscid limit of stochastic damped 2D Navier-Stokes equations
We consider the inviscid limit of the stochastic damped 2D Navier- Stokes equations. We prove that, when the viscosity vanishes, the stationary solution of the stochastic damped Navier-Stokes equations converges to a stationary solution of the stochastic damped Euler equation and that the rate of dissipation of enstrop...
1212.0509v3
2014-01-13
NLSE for quantum plasmas with the radiation damping
We consider contribution of the radiation damping in the quantum hydrodynamic equations for spinless particles. We discuss possibility of obtaining of corresponding non-linear Schrodinger equation (NLSE) for the macroscopic wave function. We compare contribution of the radiation damping with weakly (or semi-) relativis...
1401.2829v1
2014-09-26
An ultimate storage ring lattice with vertical emittance generated by damping wigglers
We discuss the approach of generating round beams for ultimate storage rings using vertical damping wigglers (with horizontal magnetic field). The vertical damping wigglers provide damping and excite vertical emittance. This eliminates the need to generate large linear coupling that is impractical with traditional off-...
1409.7452v2
2017-03-01
Behaviors of the energy of solutions of two coupled wave equations with nonlinear damping on a compact manifold with boundary
In this paper we study the behaviors of the the energy of solutions of coupled wave equations on a compact manifold with boundary in the case of indirect nonlinear damping . Only one of the two equations is directly damped by a localized nonlinear damping term. Under geometric conditions on both the coupling and the da...
1703.00172v1
2017-06-02
Vanishing viscosity limit for global attractors for the damped Navier--Stokes system with stress free boundary conditions
We consider the damped and driven Navier--Stokes system with stress free boundary conditions and the damped Euler system in a bounded domain $\Omega\subset\mathbf{R}^2$. We show that the damped Euler system has a (strong) global attractor in~$H^1(\Omega)$. We also show that in the vanishing viscosity limit the global a...
1706.00607v1
2018-01-20
Long time dynamics for weakly damped nonlinear Klein-Gordon equations
We continue our study of damped nonlinear Klein-Gordon equations. In our previous work we considered fixed positive damping and proved a form of the soliton resolution conjecture for radial solutions. In contrast, here we consider damping which decreases in time to 0. In the class of radial data we again establish soli...
1801.06735v1
2018-02-28
Nonexistence of global solutions of wave equations with weak time-dependent damping and combined nonlinearity
In our previous two works, we studied the blow-up and lifespan estimates for damped wave equations with a power nonlinearity of the solution or its derivative, with scattering damping independently. In this work, we are devoted to establishing a similar result for a combined nonlinearity. Comparing to the result of wav...
1802.10273v1
2018-11-12
Choking non-local magnetic damping in exchange biased ferromagnets
We investigated the temperature dependence of the magnetic damping in the exchange biased Pt/ Fe50Mn50 /Fe20Ni80 /SiOx multilayers. In samples having a strong exchange bias, we observed a drastic decrease of the magnetic damping of the FeNi with increasing temperature up to the blocking temperature. The results essenti...
1811.04821v1
2019-05-23
Escaping Locally Optimal Decentralized Control Polices via Damping
We study the evolution of locally optimal decentralized controllers with the damping of the control system. Empirically it is shown that even for instances with an exponential number of connected components, damping merges all local solutions to the one global solution. We characterize the evolution of locally optimal ...
1905.09915v1
2019-08-22
Some remarks on the asymptotic profile of solutions to structurally damped $σ$-evolution equations
In this paper, we are interested in analyzing the asymptotic profiles of solutions to the Cauchy problem for linear structurally damped $\sigma$-evolution equations in $L^2$-sense. Depending on the parameters $\sigma$ and $\delta$ we would like to not only indicate approximation formula of solutions but also recognize ...
1908.08492v1
2019-09-18
Global smooth solutions of the damped Boussinesq equations with a class of large initial data
The global regularity problem concerning the inviscid Boussinesq equations remains an open problem. In an attempt to understand this problem, we examine the damped Boussinesq equations and study how damping affects the regularity of solutions. In this paper, we consider the global existence to the damped Boussinesq equ...
1909.08360v1
2020-02-15
Asymptotic profile and optimal decay of solutions of some wave equations with logarithmic damping
We introduce a new model of the nonlocal wave equations with a logarithmic damping mechanism. We consider the Cauchy poroblem for the new model in the whole space. We study the asymptotic profile and optimal decay and blowup rates of solutions as time goes to infinity. The damping terms considered in this paper is not ...
2002.06319v1
2020-05-13
Weak Input to state estimates for 2D damped wave equations with localized and non-linear damping
In this paper, we study input-to-state (ISS) issues for damped wave equations with Dirichlet boundary conditions on a bounded domain of dimension two. The damping term is assumed to be non-linear and localized to an open subset of the domain. In a first step, we handle the undisturbed case as an extension of a previous...
2005.06206v3
2020-07-25
Decay for the Kelvin-Voigt damped wave equation: Piecewise smooth damping
We study the energy decay rate of the Kelvin-Voigt damped wave equation with piecewise smooth damping on the multi-dimensional domain. Under suitable geometric assumptions on the support of the damping, we obtain the optimal polynomial decay rate which turns out to be different from the one-dimensional case studied in ...
2007.12994v2
2020-08-12
From Lieb-Thirring inequalities to spectral enclosures for the damped wave equation
Using a correspondence between the spectrum of the damped wave equation and non-self-adjoint Schroedinger operators, we derive various bounds on complex eigenvalues of the former. In particular, we establish a sharp result that the one-dimensional damped wave operator is similar to the undamped one provided that the L^...
2008.05176v1
2021-08-02
Wide-Area Damping Control for Interarea Oscillations in Power Grids Based on PMU Measurements
In this paper, a phasor measurement unit (PMU)-based wide-area damping control method is proposed to damp the interarea oscillations that threaten the modern power system stability and security. Utilizing the synchronized PMU data, the proposed almost model-free approach can achieve an effective damping for the selecte...
2108.01193v1
2021-09-05
Regularity of the semigroups associated with some damped coupled elastic systems II: a nondegenerate fractional damping case
In this paper, we examine regularity issues for two damped abstract elastic systems; the damping and coupling involve fractional powers $\mu, \theta$, with $0 \leq \mu , \theta \leq 1$, of the principal operators. The matrix defining the coupling and damping is nondegenerate. This new work is a sequel to the degenerate...
2109.02044v1
2021-09-28
A robust and efficient line search for self-consistent field iterations
We propose a novel adaptive damping algorithm for the self-consistent field (SCF) iterations of Kohn-Sham density-functional theory, using a backtracking line search to automatically adjust the damping in each SCF step. This line search is based on a theoretically sound, accurate and inexpensive model for the energy as...
2109.14018v3
2021-11-17
Spectral asymptotics for the vectorial damped wave equation
The eigenfrequencies associated to a scalar damped wave equation are known to belong to a band parallel to the real axis. In [Sj{\"o}00] J. Sj{\"o}strand showed that up to a set of density 0, the eigenfrequencies are confined in a thinner band determined by the Birkhoff limits of the damping term. In this article we sh...
2111.08982v1
2021-12-13
Rotons and their damping in elongated dipolar Bose-Einstein condensates
We discuss finite temperature damping of rotons in elongated Bose-condensed dipolar gases, which are in the Thomas-Fermi regime in the tightly confined directions. The presence of many branches of excitations which can participate in the damping process, is crucial for the Landau damping and results in significant incr...
2112.06835v2
2022-03-12
Asymptotic expansion of solutions to the wave equation with space-dependent damping
We study the large time behavior of solutions to the wave equation with space-dependent damping in an exterior domain. We show that if the damping is effective, then the solution is asymptotically expanded in terms of solutions of corresponding parabolic equations. The main idea to obtain the asymptotic expansion is th...
2203.06360v1
2022-10-27
Sharp polynomial decay for polynomially singular damping on the torus
We study energy decay rates for the damped wave equation with unbounded damping, without the geometric control condition. Our main decay result is sharp polynomial energy decay for polynomially controlled singular damping on the torus. We also prove that for normally $L^p$-damping on compact manifolds, the Schr\"odinge...
2210.15697v3
2023-09-27
Dispersion and damping of ion-acoustic waves in the plasma with a regularized kappa-distribution
The dispersion and damping of ion-acoustic waves in the plasma with a regularized kappa-distribution are studied. The generalized dispersion relation and damping rate are derived, which both depend significantly on the parameters alpha and kappa. The numerical analyses show that the wave frequency and the damping rate ...
2309.15885v1
2023-11-16
Near-optimal Closed-loop Method via Lyapunov Damping for Convex Optimization
We introduce an autonomous system with closed-loop damping for first-order convex optimization. While, to this day, optimal rates of convergence are only achieved by non-autonomous methods via open-loop damping (e.g., Nesterov's algorithm), we show that our system is the first one featuring a closed-loop damping while ...
2311.10053v1
2024-02-05
Fractional damping induces resonant behavior in the Duffing oscillator
The interaction between the fractional order parameter and the damping parameter can play a relevant role for introducing different dynamical behaviors in a physical system. Here, we study the Duffing oscillator with a fractional damping term. Our findings show that for certain values of the fractional order parameter,...
2402.02940v1
2024-03-13
Impact of Decoherence on Average Correlation
This article presents a comprehensive study of the impact of decoherence on the average correlation for pure quantum states. We explore two primary mechanisms of decoherence: phase damping and amplitude damping, each having distinct effects on quantum systems. Phase damping, which describes the loss of quantum coherenc...
2403.10551v1
1998-02-18
Damping rates of hot Giant Dipole Resonances
The damping rate of hot giant dipole resonances (GDR) is investigated. Besides Landau damping we consider collisions and density fluctuations as contributions to the damping of GDR. Within the nonequilibrium Green's function method we derive a non-Markovian kinetic equation. The linearization of the latter one leads to...
9802052v2
2015-12-11
Ultra-low magnetic damping of a metallic ferromagnet
The phenomenology of magnetic damping is of critical importance for devices that seek to exploit the electronic spin degree of freedom since damping strongly affects the energy required and speed at which a device can operate. However, theory has struggled to quantitatively predict the damping, even in common ferromagn...
1512.03610v1
2020-05-12
Effective Viscous Damping Enables Morphological Computation in Legged Locomotion
Muscle models and animal observations suggest that physical damping is beneficial for stabilization. Still, only a few implementations of mechanical damping exist in compliant robotic legged locomotion. It remains unclear how physical damping can be exploited for locomotion tasks, while its advantages as sensor-free, a...
2005.05725v2
2022-02-10
Non-stationary Anderson acceleration with optimized damping
Anderson acceleration (AA) has a long history of use and a strong recent interest due to its potential ability to dramatically improve the linear convergence of the fixed-point iteration. Most authors are simply using and analyzing the stationary version of Anderson acceleration (sAA) with a constant damping factor or ...
2202.05295v1
2023-06-30
A finite element method to compute the damping rate of oscillating fluids inside microfluidic nozzles
We introduce a finite element method for computing the damping rate of fluid oscillations in nozzles of drop-on-demand (DoD) microfluidic devices. Accurate knowledge of the damping rates for the least-damped oscillation modes following droplet ejection is paramount for assessing jetting stability at higher jetting freq...
2307.00094v1
2024-01-18
Multithermal apparent damping of slow waves due to strands with a Gaussian temperature distribution
Context. Slow waves in solar coronal loops are strongly damped. The current theory of damping by thermal conduction cannot explain some observational features.\n Aims. We investigate the propagation of slow waves in a coronal loop built up from strands of different temperatures. \n Methods. We consider the loop to have...
2401.09803v1
2001-03-09
Rayleigh Scattering and Microwave Background Fluctuations
During the recombination epoch, cosmic background photons couple not only to free electrons through Thompson scattering, but also to the neutral hydrogen through Rayleigh scattering. This latter is ~2% effect for photons near the peak of the photon energy distribution at z=800 and a ~0.2% effect at z=1100. Including Ra...
0103149v3
2001-03-19
Fluctuations in the Cosmic Microwave Background II: $C_\ell$ at Large and Small $\ell$
General asymptotic formulas are given for the coefficient $C_\ell$ of the term of multipole number $\ell$ in the temperature correlation function of the cosmic microwave background, in terms of scalar and dipole form factors introduced in a companion paper. The formulas apply in two overlapping limits: for $\ell\gg 1$ ...
0103281v2
2003-01-22
Propagation model for cosmic ray species in the Galaxy
In a recent paper (Moskalenko et al., 2002), it has been shown that the flux of secondary cosmic ray (CR) antiprotons appears to be contradictory to measurements of secondary to primary nuclei ratios in cosmic rays when calculated in the same Galactic propagation model. The contradiction appears as a value of the diffu...
0301420v1
2005-02-28
On the existence of three-dimensional hydrostatic and magnetostatic equilibria of self-gravitating fluid bodies
(Abridged) We develop an analytical spectral method to solve the equations of equilibrium for a self-gravitating, magnetized fluid body, under the only hypotheses that (a) the equation of state is isothermal, (b) the configuration is scale-free, and (c) the body is electrically neutral. All physical variables are repre...
0502584v1
2006-06-14
Electron Acceleration in Solar Flares: Theory of Spectral Evolution
Context: Stochastic acceleration is thought to be a key mechanism in the energization of solar flare electrons. Aims: We study whether stochastic acceleration can reproduce the observed soft-hard-soft evolution of the spectral features of the hard X-ray emitted by suprathermal electron. We pay special attention to th...
0606339v2
1996-07-04
Continuous Elastic Phase Transitions in Pure and Disordered Crystals
We review the theory of second--order (ferro--)elastic phase transitions, where the order parameter consists of a certain linear combination of strain tensor components, and the accompanying soft mode is an acoustic phonon. In three--dimensional crystals, the softening can occur in one-- or two--dimensional soft sector...
9607028v2
2004-03-28
Bilayer Membrane in Confined Geometry: Interlayer Slide and Steric Repulsion
We derived free energy functional of a bilayer lipid membrane from the first principles of elasticity theory. The model explicitly includes position-dependent mutual slide of monolayers and bending deformation. Our free energy functional of liquid-crystalline membrane allows for incompressibility of the membrane and va...
0403676v1
1995-06-26
A Stochastic Approach to Thermal Fluctuations during a First Order Electroweak Phase Transition
We investigate the role played by subcritical bubbles at the onset of the electroweak phase transition. Treating the configuration modelling the thermal fluctuations around the homogeneous zero configuration of the Higgs field as a stochastic variable, we describe its dynamics by a phenomenological Langevin equation. T...
9506419v1
1995-10-26
Classical and quantum many-body description of bremsstrahlung in dense matter (Landau - Pomeranchuk - Migdal effect)
Some considerations about the importance of coherence effects for bremsstrahlung processes in non--equilibrium dense matter (Landau - Pomeranchuk - Migdal - effect) are presented. They are of particular relevance for the application to photon - and di-lepton production from high energy nuclear collisions, to gluon radi...
9510417v1
1997-10-15
Domain Walls Out of Equilibrium
We study the non-equilibrium dynamics of domain walls in real time for $\phi^4$ and Sine Gordon models in 1+1 dimensions in the dilute regime. The equation of motion for the collective coordinate is obtained by integrating out the meson excitations around the domain wall to one-loop order. The real-time non-equilibrium...
9710359v2
2005-01-06
Non-statistical fluctuations for deep inelastic processes in 27Al + 27Al
The excitation functions for different fragments produced in the 27Al + 27Al dissipative collisions have been measured in steps of 250 keV in the energy range 122 - 132 MeV. Deep inelastic processes have been selected by integrating events over a total kinetic energy loss window of 12 MeV between 20 and 32 MeV. Large f...
0501003v1
2004-10-14
Cold Strongly Coupled Atoms Make a Near-perfect Liquid
Feshbach resonances of trapped ultracold alkali atoms allow to vary the atomic scattering length a. At very large values of a the system enters an universal strongly coupled regime in which its properties--the ground state energy, pressure {\it etc.}--become independent of a. We discuss transport properties of such sys...
0410067v2