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2018-02-20
Ultrafast magnetization dynamics in pure and doped Heusler and inverse Heusler alloys
By using a multiscale approach based on first-principles density functional theory combined with atomistic spin dynamics, we investigate the electronic structure and magnetization dynamics of an inverse Heusler and a Heusler compound and their alloys, i. e. Mn$_{2-x}Z_x$CoAl and Mn$_{2-x}Z_x$VAl, where $Z$ = Mo, W, Os ...
1802.07195v1
2019-01-24
Reaffirmation of Cosmological Oscillations in the Scale Factor from the Pantheon Compilation of 1048 Type Ia Supernovae
We observe damped temporal oscillations in the scale factor at a dominant frequency of ~ 7 cycles/Hubble-time in the Pantheon Compilation of 1048 type Ia supernovae (SNe). The residual oscillations observed in the Pantheon data closely matches and reaffirms our initial observation of oscillations from earlier SNe data ...
1901.10311v3
2019-03-14
A new class of accelerated regularization methods, with application to bioluminescence tomography
In this paper we propose a new class of iterative regularization methods for solving ill-posed linear operator equations. The prototype of these iterative regularization methods is in the form of second order evolution equation with a linear vanishing damping term, which can be viewed not only as an extension of the as...
1903.05972v2
2019-05-15
Stop-and-Go Suppression in Two-Class Congested Traffic
This paper develops boundary feedback control laws in order to damp out traffic oscillations in the congested regime of the linearized two-class Aw-Rascle (AR) traffic model. The macroscopic second-order two-class AR traffic model consists of four hyperbolic partial differential equations (PDEs) describing the dynamics...
1905.06476v1
2019-10-07
Chiral spin-wave velocities induced by all-garnet interfacial Dzyaloshinskii-Moriya interaction in ultrathin yttrium iron garnet films
Spin waves can probe the Dzyaloshinskii-Moriya interaction (DMI) which gives rise to topological spin textures, such as skyrmions. However, the DMI has not yet been reported in yttrium iron garnet (YIG) with arguably the lowest damping for spin waves. In this work, we experimentally evidence the interfacial DMI in a 7~...
1910.02599v2
2019-11-20
Extreme events in a network of heterogeneous Josephson junctions
We report rare and recurrent large spiking events in a heterogeneous network of superconducting Josephson junctions (JJ) connected through a resistive load and driven by a radio-frequency (rf) current in addition to a constant bias. The intermittent large spiking events show characteristic features of extreme events (E...
1911.10040v1
2019-12-05
Atypical Behavior of Collective Modes in Two-Dimensional Fermi Liquids
Using the Landau kinetic equation to study the non-equilibrium behavior of interacting Fermi systems is one of the crowning achievements of Landau's Fermi liquid theory. While thorough study of transport modes has been done for standard three-dimensional Fermi liquids, an equally in-depth analysis for two dimensional F...
1912.02699v2
2020-01-30
Ability of Markovian Master Equations to Model Quantum Computers and Other Systems Under Broadband Control
Most future quantum devices, including quantum computers, require control that is broadband, meaning that the rate of change of the time-dependent Hamiltonian is as fast or faster than the dynamics it generates. In many areas of quantum physics, including quantum technology, one must include dissipation and decoherence...
2001.11160v1
2020-02-06
Effects of transition-metal spacers on the spin-orbit torques, spin Hall magnetoresistance, and magnetic anisotropy of Pt/Co bilayers
We studied the effect of inserting 0.5 nm-thick spacer layers (Ti, V, Cr, Mo, W) at the Pt/Co interface on the spin-orbit torques, Hall effect, magnetoresistance, saturation magnetization, and magnetic anisotropy. We find that the damping-like spin-orbit torque decreases substantially for all samples with a spacer laye...
2002.02162v1
2020-04-30
Unifying femtosecond and picosecond single-pulse magnetic switching in GdFeCo
Many questions are still open regarding the physical mechanisms behind the magnetic switching in GdFeCo alloys by single optical pulses. Phenomenological models suggest a femtosecond scale exchange relaxation between sublattice magnetization as the driving mechanism for switching. The recent observation of thermally in...
2004.14844v1
2020-06-12
Tidal Asteroseismology: Possible Evidence of Non-linear Mode Coupling in an Equilibrium State in Kepler Eclipsing Binary KIC 3230227
Previously, a series of tidally-excited oscillations were discovered in the eccentric eclipsing binary KIC 3230227. The pulsation amplitudes and phases suggest the observed oscillations are prograde quadruple modes. In this paper, we refine the analysis and extract more oscillation frequencies. We also study the tempor...
2006.07417v1
2021-02-22
Anisotropic cosmological models in Horndeski gravity
It was found recently that the anisotropies in the homogeneous Bianchi I cosmology considered within the context of a specific Horndeski theory are damped near the initial singularity instead of being amplified. In this work we extend the analysis of this phenomenon to cover the whole of the Horndeski family. We find t...
2102.10981v2
2021-03-18
Size limit of superparamagnetic inclusions in dust grains and difficulty of magnetic grain alignment in protoplanetary disks
Alignment of non-spherical grains with magnetic fields is an important problem as it lays the foundation of probing magnetic fields with polarized dust thermal emissions. In this paper, we investigate the feasibility of magnetic alignment in protoplanetary disks (PPDs). We use an alignment condition that Larmor precess...
2103.10243v1
2021-05-19
Viscoelasticity and elastocapillarity effects in the impact of drops on a repellent surface
We investigate freely expanding viscoelastic sheets. The sheets are produced by the impact of drops on a quartz plate covered with a thin layer of liquid nitrogen that suppresses shear viscous dissipation as a result of the cold Leidenfrost effect. The time evolution of the sheet is simultaneously recorded from top and...
2105.09244v1
2021-06-23
The dynamical exponent of a quantum critical itinerant ferromagnet: a Monte Carlo study
We consider the effect of the coupling between 2D quantum rotors near an XY ferromagnetic quantum critical point and spins of itinerant fermions. We analyze how this coupling affects the dynamics of rotors and the self-energy of fermions.A common belief is that near a $q=0$ ferromagnetic transition, fermions induce an ...
2106.12601v3
2021-08-20
Cosmic-Ray Transport in Simulations of Star-forming Galactic Disks
Cosmic ray transport on galactic scales depends on the detailed properties of the magnetized, multiphase interstellar medium (ISM). In this work, we post-process a high-resolution TIGRESS magnetohydrodynamic simulation modeling a local galactic disk patch with a two-moment fluid algorithm for cosmic ray transport. We c...
2108.09356v1
2021-09-13
Control of magnetization dynamics by substrate orientation in YIG thin films
Yttrium Iron Garnet (YIG) and bismuth (Bi) substituted YIG (Bi0.1Y2.9Fe5O12, BYG) films are grown in-situ on single crystalline Gadolinium Gallium Garnet (GGG) substrates [with (100) and (111) orientations] using pulsed laser deposition (PLD) technique. As the orientation of the Bi-YIG film changes from (100) to (111),...
2109.05901v1
2021-12-24
Excitation of ion-acoustic waves by non-linear finite-amplitude standing Alfvén waves
We investigate, using a multi-fluid approach, the main properties of standing ion-acoustic modes driven by nonlinear standing Alfv\'en waves. The standing character of the Alfv\'enic pump is because we study the superposition of two identical circularly polarised counter-propagating waves. We consider parallel propagat...
2112.13048v1
2021-12-25
Internal modes and radiation damping for quadratic Klein-Gordon in 3D
We consider Klein-Gordon equations with an external potential $V$ and a quadratic nonlinearity in $3+1$ space dimensions. We assume that $V$ is regular and decaying and that the (massive) Schr\"odinger operator $H=-\Delta+V+m^2$ has a positive eigenvalue $\lambda^2<m^2$ with associated eigenfunction $\phi.$ This is a s...
2112.13163v2
2022-01-17
Sizing of Energy Storage System for Virtual Inertia Emulation
The infusion of renewable energy sources into the conventional synchronous generation system decreases the overall system inertia and negatively impacts the stability of its primary frequency response. The lowered inertia is due to the absence of inertia in some of the renewable energy-based systems. To maintain the st...
2201.06566v2
2022-04-26
Galactic seismology: joint evolution of impact-triggered stellar and gaseous disc corrugations
Evidence for wave-like corrugations are well established in the Milky Way and in nearby disc galaxies. These were originally detected as a displacement of the interstellar medium about the midplane, either in terms of vertical distance or vertical velocity. Over the past decade, similar patterns have emerged in the Mil...
2204.12096v2
2022-04-28
Low-frequency resolvent analysis of the laminar oblique shock wave / boundary layer interaction
Resolvent analysis is used to study the low-frequency behaviour of the laminar oblique shock wave / boundary layer interaction (SWBLI). It is shown that the computed optimal gain, which can be seen as a transfer function of the system, follows a first-order low-pass filter equation, recovering the results of Touber and...
2204.13527v1
2022-09-01
Growth parameters of Bi0.1Y2.9Fe5O12 thin films for high frequency applications
The growth and characterization of Bismuth (Bi) substituted YIG (Bi-YIG, Bi0.1Y2.9Fe5O12) thin films are reported. Pulsed laser deposited (PLD) films with thicknesses ranging from 20 to 150 nm were grown on Gadolinium Gallium Garnet substrates. Two substrate orientations of (100) and (111) were considered. The enhanced...
2209.00558v1
2022-09-02
Identical damped harmonic oscillators described by coherent states
Some aspects of quantum damped harmonic oscillator (DHO) obeying a Markovian master equation are considered in the absence of thermal noise. The continuity equation is derived and Bohmian trajectories are constructed. As a solution of the master equation, we take a single coherent state and compute analytically the rel...
2209.00914v2
2022-11-27
Dynamic surface tension of the pure liquid-vapor interface subjected to the cyclic loads
We demonstrate a methodology for computationally investigating the mechanical response of a pure molten lead surface system to the lateral mechanical cyclic loads and try to answer the question: how dose the dynamically driven liquid surface system follow the classical physics of the elastic-driven oscillation? The ste...
2211.14766v1
2023-11-07
Strong electron-phonon coupling in Ba$_{1-x}$Sr$_x$Ni$_2$As$_2$
The charge density wave (CDW) or nematicity has been found to coexist with superconductivity in many systems. It is thus interesting that the superconducting transition temperature $T_c$ in the doped BaNi$_2$As$_2$ system can be enhanced up to six times as the CDW or nematicity in the undoped compound is suppressed. He...
2311.03649v2
2023-11-21
Numerical modelling of bulk viscosity in neutron stars
The early post-merger phase of a binary neutron-star coalescence is shaped by characteristic rotational velocities as well as violent density oscillations and offers the possibility to constrain the properties of neutron star matter by observing the gravitational wave emission. One possibility to do so is the investiga...
2311.13027v1
2023-12-24
Transient growth of wavelet-based resolvent modes in the buffer layer of wall-bounded turbulence
In this work, we study the transient growth of the principal resolvent modes in the minimal flow unit using a reformulation of resolvent analysis in a time-localized wavelet basis. We target the most energetic spatial wavenumbers for the minimal flow unit and obtain modes that are constant in the streamwise direction a...
2312.15465v1
2024-02-27
Fourier analysis of near-field patterns generated by propagating polaritons
Scattering-type scanning near-field optical microscope (s-SNOM) has become an essential tool to study polaritons - quasiparticles of light coupled to collective charge oscillations - via direct probing of their near field with a spatial resolution far beyond the diffraction limit. However, extraction of the polariton c...
2402.17225v2
2000-09-11
Numerical Studies on Locally Damped Structures
In the JLC/NLC X-band linear collider, it is essential to reduce the long-range dipole wakefields in the accelerator structure to prevent beam break up (BBU) and emittance degradation. The two methods of reducing the long-range wakefields are detuning and damping. Detuning reduces the wakefields rapidly as the dipole m...
0009039v1
2015-03-13
A one-step optimal energy decay formula for indirectly nonlinearly damped hyperbolic systems coupled by velocities
In this paper, we consider the energy decay of a damped hyperbolic system of wave-wave type which is coupled through the velocities. We are interested in the asymptotic properties of the solutions of this system in the case of indirect nonlinear damping, i.e. when only one equation is directly damped by a nonlinear dam...
1503.04126v1
2015-08-21
Radiative damping in wave guide based FMR measured via analysis of perpendicular standing spin waves in sputtered Permalloy films
The damping $\alpha$ of the spinwave resonances in 75 nm, 120 nm, and 200nm -thick Permalloy films is measured via vector-network-analyzer ferromagnetic-resonance (VNA-FMR) in the out-of-plane geometry. Inductive coupling between the sample and the waveguide leads to an additional radiative damping term. The radiative ...
1508.05265v1
2016-02-23
Experimental Investigation of Temperature-Dependent Gilbert Damping in Permalloy Thin Films
The Gilbert damping of ferromagnetic materials is arguably the most important but least understood phenomenological parameter that dictates real-time magnetization dynamics. Understanding the physical origin of the Gilbert damping is highly relevant to developing future fast switching spintronics devices such as magnet...
1602.07325v1
2017-09-29
Non-local Gilbert damping tensor within the torque-torque correlation model
An essential property of magnetic devices is the relaxation rate in magnetic switching which depends strongly on the damping in the magnetisation dynamics. It was recently measured that damping depends on the magnetic texture and, consequently, is a non-local quantity. The damping enters the Landau-Lifshitz-Gilbert equ...
1709.10365v1
2022-09-28
Tunable nonlinear damping in parametric regime
Nonlinear damping plays a significant role in several area of physics and it is becoming increasingly important to understand its underlying mechanism. However, microscopic origin of nonlinear damping is still a debatable topic. Here, we probe and report nonlinear damping in a highly tunable MoS2 nano mechanical drum r...
2209.14120v1
2005-11-07
The Effects of Alfven Waves and Radiation Pressure in Dusty Winds of Late-Type Stars. II. Dust-Cyclotron Damping
There are in the literature several theories to explain the mass loss in stellar winds. In particular, for late-type stars, some authors have proposed a wind model driven by an outward-directed flux of damped Alfven waves. The winds of these stars present great amounts of dust particles that, if charged, can give rise ...
0511192v2
2013-09-11
Initial versus tangent stiffness-based Rayleigh damping in inelastic time history seismic analyses
In the inelastic time history analyses of structures in seismic motion, part of the seismic energy that is imparted to the structure is absorbed by the inelastic structural model, and Rayleigh damping is commonly used in practice as an additional energy dissipation source. It has been acknowledged that Rayleigh damping...
1309.2741v1
2017-07-14
Damping of gravitational waves by matter
We develop a unified description, via the Boltzmann equation, of damping of gravitational waves by matter, incorporating collisions. We identify two physically distinct damping mechanisms -- collisional and Landau damping. We first consider damping in flat spacetime, and then generalize the results to allow for cosmolo...
1707.05192v2
2001-08-28
Galaxy number counts in the Hubble Deep Field as a strong constraint on a hierarchical galaxy formation model
Number counts of galaxies are re-analyzed using a semi-analytic model (SAM) of galaxy formation based on the hierarchical clustering scenario. We have determined the astrophysical parameters in the SAM that reproduce observations of nearby galaxies, and used them to predict the number counts and redshifts of faint gala...
0108433v1
2010-05-07
Quantum phase transitions of metals in two spatial dimensions: II. Spin density wave order
We present a field-theoretic renormalization group analysis of Abanov and Chubukov's model of the spin density wave transition in two dimensional metals. We identify the independent field scale and coupling constant renormalizations in a local field theory, and argue that the damping constant of spin density wave fluct...
1005.1288v2
2017-08-03
Evolution of the interfacial perpendicular magnetic anisotropy constant of the Co$_2$FeAl/MgO interface upon annealing
We investigate thickness series of films of the Heusler alloy Co$_2$FeAl in order to study the effect of annealing on the interface with a MgO layer and on the bulk magnetic properties. Our results reveal that while the perpendicular interface anisotropy constant $K^{\perp}_{\rm S}$ is zero for the as-deposited samples...
1708.01126v2
2023-09-10
Scalar fields around a loop quantum gravity black hole in de Sitter spacetime: Quasinormal modes, late-time tails and strong cosmic censorship
Loop quantum gravity, as one branch of quantum gravity, holds the potential to explore the fundamental nature of black holes. Recently, according to the quantum Oppenheimer-Snyder model in loop quantum cosmology, a novel loop quantum corrected black hole in de Sitter spacetime has been discovered. Here, we first invest...
2309.04962v2
2006-05-22
The entanglement of damped noon-state and its performance in phase measurement
The state evolution of the initial optical \textit{noon} state is investigated. The residue entanglement of the state is calculated after it is damped by amplitude and phase damping. The relative entropy of entanglement of the damped state is exactly obtained. The performance of direct application of the damped \textit...
0605184v1
2007-10-04
Channel-Adapted Quantum Error Correction for the Amplitude Damping Channel
We consider error correction procedures designed specifically for the amplitude damping channel. We analyze amplitude damping errors in the stabilizer formalism. This analysis allows a generalization of the [4,1] `approximate' amplitude damping code of quant-ph/9704002. We present this generalization as a class of [2(M...
0710.1052v1
2011-11-30
Local phase damping of single qubits sets an upper bound on the phase damping rate of entangled states
I derive an inequality in which the phase damping rates of single qubits set an upper bound for the phase damping rate of entangled states of many qubits. The derivation is based on two assumptions: first, that the phase damping can be described by a dissipator in Lindblad form and, second, that the phase damping prese...
1111.7152v2
2012-05-11
Quantum dynamics of the damped harmonic oscillator
The quantum theory of the damped harmonic oscillator has been a subject of continual investigation since the 1930s. The obstacle to quantization created by the dissipation of energy is usually dealt with by including a discrete set of additional harmonic oscillators as a reservoir. But a discrete reservoir cannot direc...
1205.2545v1
2014-02-28
Escape rate for the power-law distribution in low-to-intermediate damping
Escape rate in the low-to-intermediate damping connecting the low damping with the intermediate damping is established for the power-law distribution on the basis of flux over population theory. We extend the escape rate in the low damping to the low-to-intermediate damping, and get an expression for the power-law dist...
1402.7194v2
2015-03-21
On damping created by heterogeneous yielding in the numerical analysis of nonlinear reinforced concrete frame elements
In the dynamic analysis of structural engineering systems, it is common practice to introduce damping models to reproduce experimentally observed features. These models, for instance Rayleigh damping, account for the damping sources in the system altogether and often lack physical basis. We report on an alternative pat...
1503.07122v1
2016-01-20
Introduction to Landau Damping
The mechanism of Landau damping is observed in various systems from plasma oscillations to accelerators. Despite its widespread use, some confusion has been created, partly because of the different mechanisms producing the damping but also due to the mathematical subtleties treating the effects. In this article the ori...
1601.05227v1
2018-07-25
Regularity and asymptotic behaviour for a damped plate-membrane transmission problem
We consider a transmission problem where a structurally damped plate equation is coupled with a damped or undamped wave equation by transmission conditions. We show that exponential stability holds in the damped-damped situation and polynomial stability (but no exponential stability) holds in the damped-undamped case. ...
1807.09730v1
2021-08-04
Nonlinear fluid damping of elastically mounted pitching wings in quiescent water
We experimentally study the nonlinear fluid damping of a rigid but elastically mounted pitching wing in the absence of a freestream flow. The dynamics of the elastic mount are simulated using a cyber-physical system. We perturb the wing and measure the fluid damping coefficient from damped oscillations over a large ran...
2108.02090v1
2019-06-18
Phase dynamics of effective drag and lift in vortex-induced vibration at low mass-damping
In this work, we investigate the dynamics of vortex-induced vibration of an elastically mounted cylinder with very low values of mass and damping. We use two methods to investigate this canonical problem: first we calculate the instantaneous phase between the cylinder motion and the fluid forcing; second we decompose t...
1906.07375v2
2002-11-03
Damping of coupled phonon--plasmon modes
The effect of free carriers on dispersion and damping of coupled phonon-plasmon modes is considered in the long-wave approximation. The electron and phonon scattering rate as well as Landau damping are taken into account.
0211040v1
2002-02-01
On "the authentic damping mechanism" of the phonon damping model
Some general features of the phonon damping model are presented. It is concluded that the fits performed within this model have no physical content.
0202006v1
2010-12-20
Global attractors for the one dimensional wave equation with displacement dependent damping
We study the long-time behavior of solutions of the one dimensional wave equation with nonlinear damping coefficient. We prove that if the damping coefficient function is strictly positive near the origin then this equation possesses a global attractor.
1012.4455v1
2018-01-28
Observations of excitation and damping of transversal oscillation in coronal loops by AIA/SDO
The excitation and damping of transversal coronal loop oscillations and quantitative relation between damping time, damping quality (damping time per period), oscillation amplitude, dissipation mechanism and the wake phenomena are investigated. The observed time series data with the \textit{Atmospheric Imaging Assembly...
1801.09217v1
1999-11-16
Probing supernovae ejecta by Halpha damping wings
It is predicted that H$\alpha$ emission line at the early nebular epoch of type II-P supernovae may display robust observational effects of damping wings. This is illustrated by Monte-Carlo simulations. The strength of damping wing effects may be used to constrain parameters of the line-emitting zone. An anomalous reds...
9911300v1
2009-01-23
Rheological Interpretation of Rayleigh Damping
Damping is defined through various terms such as energy loss per cycle (for cyclic tests), logarithmic decrement (for vibration tests), complex modulus, rise-time or spectrum ratio (for wave propagation analysis), etc. For numerical modeling purposes, another type of damping is frequently used : it is called Rayleigh d...
0901.3717v1
2015-05-06
Remarks on the asymptotic behavior of the solution of an abstract damped wave equation
We study an abstract damped wave equation. We prove that the solution of the damped wave equation becomes closer to the solution of a heat type equation as time tend to infinity. As an application of our approach, we also study the asymptotic behavior of the damped wave equation in Euclidean space under the geometric c...
1505.01794v2
2017-01-18
Two types of spurious damping forces potentially modeled in numerical seismic nonlinear response history analysis
The purpose of this paper is to provide practitioners with further insight into spurious damping forces that can be generated in nonlinear seismic response history analyses (RHA). The term 'spurious' is used to refer to damping forces that are not present in an elastic system and appear as nonlinearities develop: such ...
1701.05092v1
2017-02-02
Exponential stability for a coupled system of damped-undamped plate equations
We consider the transmission problem for a coupled system of undamped and structurally damped plate equations in two sufficiently smooth and bounded subdomains. It is shown that, independently of the size of the damped part, the damping is strong enough to produce uniform exponential decay of the energy of the coupled ...
1702.00637v1
2017-09-11
Comparison of damping mechanisms for transverse waves in solar coronal loops
We present a method to assess the plausibility of alternative mechanisms to explain the damping of magnetohydrodynamic (MHD) transverse waves in solar coronal loops. The considered mechanisms are resonant absorption of kink waves in the Alfv\'en continuum, phase-mixing of Alfv\'en waves, and wave leakage. Our methods m...
1709.03347v1
2019-03-25
Distributed Inter-Area Oscillation Damping Control for Power Systems by Using Wind Generators and Load Aggregators
This paper investigates the potential of wind turbine generators (WTGs) and load aggregators (LAs) to provide supplementary damping control services for low frequency inter-area oscillations (LFOs) through the additional distributed damping control units (DCUs) proposed in their controllers. In order to provide a scala...
1903.10135v1
2019-08-19
Spectral determinant for the damped wave equation on an interval
We evaluate the spectral determinant for the damped wave equation on an interval of length $T$ with Dirichlet boundary conditions, proving that it does not depend on the damping. This is achieved by analysing the square of the damped wave operator using the general result by Burghelea, Friedlander, and Kappeler on the ...
1908.06862v1
2020-10-12
Decays rates for Kelvin-Voigt damped wave equations II: the geometric control condition
We study in this article decay rates for Kelvin-Voigt damped wave equations under a geometric control condition. We prove that when the damping coefficient is sufficiently smooth ($C^1$ vanishing nicely) we show that exponential decay follows from geometric control conditions (see~\cite{BuCh, Te12} for similar results ...
2010.05614v2
2020-12-05
On Periodical Damping Ratio of a Controlled Dynamical System with Parametric Resonances
This report provides an interpretation on the periodically varying damping ratio of a dynamical system with direct control of oscillation or vibration damping. The principal parametric resonance of the system and a new type of parametric resonance, named "zero-th order" parametric resonance, are investigated by using t...
2012.02932v1
2021-06-09
Grammage of cosmic rays in the proximity of supernova remnants embedded in a partially ionized medium
We investigate the damping of Alfv\'en waves generated by the cosmic ray resonant streaming instability in the context of the cosmic ray escape and propagation in the proximity of supernova remnants. We consider ion-neutral damping, turbulent damping and non linear Landau damping in the warm ionized and warm neutral ph...
2106.04948v1
2021-06-22
Sharp decay rate for the damped wave equation with convex-shaped damping
We revisit the damped wave equation on two-dimensional torus where the damped region does not satisfy the geometric control condition. We show that if the damping vanishes as a H\"older function $|x|^{\beta}$, and in addition, the boundary of the damped region is strictly convex, the wave is stable at rate $t^{-1+\frac...
2106.11782v3
2021-08-09
Effect of stepwise adjustment of Damping factor upon PageRank
The effect of adjusting damping factor {\alpha}, from a small initial value {\alpha}0 to the final desired {\alpha}f value, upon then iterations needed for PageRank computation is observed. Adjustment of the damping factor is done in one or more steps. Results show no improvement in performance over a fixed damping fac...
2108.04150v1
2021-08-17
Asymptotic behaviour of the wave equation with nonlocal weak damping, anti-damping and critical nonlinearity
In this paper we prove the existence of the global attractor for the wave equation with nonlocal weak damping, nonlocal anti-damping and critical nonlinearity.
2108.07395v2
2023-02-23
Buckling Metamaterials for Extreme Vibration Damping
Damping mechanical resonances is a formidable challenge in an increasing number of applications. Many of the passive damping methods rely on using low stiffness dissipative elements, complex mechanical structures or electrical systems, while active vibration damping systems typically add an additional layer of complexi...
2302.11968v1
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
2023-12-14
Nonlocal damping of spin waves in a magnetic insulator induced by normal, heavy, or altermagnetic metallic overlayer: a Schwinger-Keldysh field theory approach
Understanding spin wave (SW) damping, and how to control it to the point of being able to amplify SW-mediated signals, is one of the key requirements to bring the envisaged magnonic technologies to fruition. Even widely used magnetic insulators with low magnetization damping in their bulk, such as yttrium iron garnet, ...
2312.09140v1
1994-01-10
Radio Emitting Dust in the Free-Electron Layer of Spiral Galaxies: Testing the Disk/Halo Interface
We present a study of the radio emission from rotating, charged dust grains immersed in the ionized gas constituting the thick, H$\alpha$-emitting disk of many spiral galaxies. Using up-to-date optical constants, the charge on the grains exposed to the diffuse galactic UV flux has been calculated. An analytical approxi...
9401010v1
1994-11-01
Toward Understanding CMB Anisotropies and Their Implications
Working toward a model independent understanding of cosmic microwave background (CMB) anisotropies and their significance, we undertake a comprehensive and self-contained study of scalar perturbation theory. Initial conditions, evolution, thermal history, matter content, background dynamics, and geometry all play a rol...
9411008v1
1995-02-20
Constraints on Self-Interacting Dark Matter
We consider the growth of density perturbations in the presence of self--interacting dark matter, SIDM, proposed by Carlson, Machacek and Hall (1992). We determine the range of values for the coupling constant $\lambda$ and the particle mass $m^\prime$, for which the power spectrum lies in the ``allowed" range based on...
9502087v1
1996-12-16
Favored Variants of Cold Dark Matter Cosmologies
We discuss variants of Cold Dark Matter (CDM) dominated cosmological models that give good agreement with a range of observations. We consider models with hot dark matter, tilt, $\Omega < 1$, or a cosmological constant. We also discuss the sensitivity of the results to other parameters, such as the Hubble parameter and...
9612156v1
1997-08-07
Gravitational Magnification of the Cosmic Microwave Background
Some aspects of gravitational lensing by large scale structure (LSS) are investigated. We show that lensing causes the damping tail of the cosmic microwave background (CMB) power spectrum to fall less rapidly with decreasing angular scale than previously expected. This is due to a transfer of power from larger to small...
9708059v1
1997-09-09
Thermochemical Instabilities in Optically Thin Reacting Plasmas
The linear stability analysis of an optically thin plasma where a general reaction proceeds, including chemical relaxation time effects, is carried out . A fifth order dispersion equation (instead of the fourth order one resulting when such effects are neglected) is obtained. The new mode with the corresponding instabi...
9709079v1
1998-11-10
Temperature Anisotropies and Distortions Induced by Hot Intracluster Gas on the Cosmic Microwave Background
The power spectrum of temperature anisotropies induced by hot intracluster gas on the cosmic background radiation is calculated. For low multipoles it remains constant while at multipoles above $l>2000$ it is exponentially damped. The shape of the radiation power spectrum is almost independent of the average intraclust...
9811158v1
2001-12-13
Do the Fundamental Constants Vary in the Course of the Cosmological Evolution?
We estimate the cosmological variation of the proton-to-electron mass ratio \mu=m_p/m_e by measuring the wavelengths of molecular hydrogen transitions in the early universe. The analysis is performed using high spectral resolution observations (FWHM ~ 7 km/s) of two damped Lyman-\alpha systems at z_{abs}=2.3377 and 3.0...
0112323v2
2002-10-20
Non-Axisymmetric g-Mode and p-Mode Instability in a Hydrodynamic Thin Accretion Disk
It has been suggested that quasi-periodic oscillations of accreting X-ray sources may relate to the modes named in the title. We consider non-axisymmetric linear perturbations to an isentropic, isothermal, unmagnetized thin accretion disk. The radial wave equation, in which the number of vertical nodes (n) appears as a...
0210455v3
2003-10-23
Atomic and Molecular Absorption at High Redshift
Strong constraints on possible variations in fundamental constants can be derived from HI 21-cm and molecular rotational absorption lines observed towards quasars. With the aim of forming a statistical sample of constraints we have begun a program of systematic searches for such absorption systems. Here we describe mol...
0310672v2
2004-06-01
Constraints on Resonant Particle Production during Inflation from the Matter and CMB Power Spectra
We analyze the limits on resonant particle production during inflation based upon the power spectrum of fluctuations in matter and the cosmic microwave background. We show that such a model is consistent with features observed in the matter power spectrum deduced from galaxy surveys and damped Lyman-alpha systems at hi...
0406046v2
2005-11-28
Most precise single redshift bound to Delta alpha/alpha
Verification of theoretical predictions of an oscillating behavior of the fine-structure constant alpha with cosmic time requires high precision Delta alpha/alpha measurements at individual redshifts, while in earlier studies the mean Delta alpha/alpha values averaged over wide redshift intervals were usually reported....
0511765v1
2006-06-08
Cosmological bounds on dark matter-neutrino interactions
We investigate the cosmological effects of a neutrino interaction with cold dark matter. We postulate a neutrino that interacts with a ``neutrino interacting dark matter'' (NIDM) particle with an elastic-scattering cross section that either decreases with temperature as $T^2$ or remains constant with temperature. The n...
0606190v1
2006-07-26
Matter density perturbations in interacting quintessence models
Models with dark energy decaying into dark matter have been proposed to solve the coincidence problem in cosmology. We study the effect of such coupling in the matter power spectrum. Due to the interaction, the growth of matter density perturbations during the radiation dominated regime is slower compared to non-intera...
0607604v1
2006-11-27
High-Precision Measurements of Delta alpha/alpha from QSO Absorption Spectra
Precise radial velocity measurements (delta v/c ~ 10^{-7}) of FeII lines in damped Ly-alpha systems from very high quality VLT/UVES spectra of quasars HE0515-4414 and Q1101-264 are used to probe cosmological time dependence of the fine structure constant, alpha. It is found that between two redshifts z1 = 1.15 and z2 =...
0611803v1
2007-01-24
The N/O evolution on galaxies:the role played by the star formation history
We study the evolution of nitrogen resulting from a set of spiral and irregular galaxy models computed for a large number of input mass radial distributions and with various star formation efficiencies. We show that our models produce a nitrogen abundance evolution in good agreement with the observational data. In part...
0701691v1
1994-07-22
X-Ray Scattering Measurements of the Transient Structure of a Driven Charge-Density-Wave
We report time-resolved x-ray scattering measurements of the transient structural response of the sliding {\bf Q}$_{1}$ charge-density-wave (CDW) in NbSe$_{3}$ to a reversal of the driving electric field. The observed time scale characterizing this response at 70K varies from $\sim$ 15 msec for driving fields near thre...
9407094v1
1995-07-03
Fundamental steps of group velocity for slow surface polariton under the quantum hall effect conditions
A new type of collective electromagnetic excitations, namely surface polaritons (SP) --- in a 2D electronic layer in a high magnetic field under Quantum Hall Effect (QHE) conditions is predicted. We have found the spectrum, damping, and polarization of the SP in a wide range of frequencies $\omega$ and wavevectors $\bf...
9507001v1
1995-08-18
On the normal phase of 2D Fermi liquid with weak attraction between particles
Proceeding from the simplest field theoretical model of 2D metal, the normal phase Green functions of the weakly interacting fermions and the order parameter fluctuations (responsible for the attraction between fermions) are obtained. It is shown that taking into consideration the fluctuations mentioned leads to a cons...
9508076v1
1997-12-19
Spatiotemporal dynamics of discrete sine-Gordon lattices with sinusoidal couplings
The spatiotemporal dynamics of a damped sine-Gordon chain with sinusoidal nearest-neighbor couplings driven by a constant uniform force are discussed. The velocity characteristics of the chain versus the external force is shown. Dynamics in the high- and low-velocity regimes are investigated. It is found that in the hi...
9712226v1
1998-11-06
Intermediate temperature dynamics of one-dimensional Heisenberg antiferromagnets
We present a general theory for the intermediate temperature (T) properties of Heisenberg antiferromagnets of spin-S ions on p-leg ladders, valid for 2Sp even or odd. Following an earlier proposal for 2Sp even (Damle and Sachdev, cond-mat/9711014), we argue that an integrable, classical, continuum model of a fixed-leng...
9811083v2
1999-02-25
Mobility of Bloch Walls via the Collective Coordinate Method
We have studied the problem of the dissipative motion of Bloch walls considering a totally anisotropic one dimensional spin chain in the presence of a magnetic field. Using the so-called "collective coordinate method" we construct an effective Hamiltonian for the Bloch wall coupled to the magnetic excitations of the sy...
9902330v1
1999-04-06
Non-Fermi-liquid behavior in the Kondo lattices induced by peculiarities of magnetic ordering and spin dynamics
A scaling consideration of the Kondo lattices is performed with account of singularities in the spin excitation spectral function. It is shown that a non-Fermi-liquid (NFL) behavior between two critical values of the bare $s-f$ coupling constant occurs naturally for complicated magnetic structures with several magnon b...
9904072v3
1999-11-23
Collisionless dynamics of dilute Bose gases: Role of quantum and thermal fluctuations
We study the low-energy collective oscillations of a dilute Bose gas at finite temperature in the collisionless regime. By using a time-dependent mean-field scheme we derive for the dynamics of the condensate and noncondensate components a set of coupled equations, which we solve perturbatively to second order in the i...
9911377v1
2000-04-07
Coherent Atomic Oscillations and Resonances between Coupled Bose-Einstein Condensates with Time-Dependent Trapping Potential
We study the quantum coherent-tunneling between two Bose-Einstein condensates separated through an oscillating trap potential. The cases of slowly and rapidly varying in time trap potential are considered. In the case of a slowly varying trap we study the nonlinear resonances and chaos in the oscillations of the relati...
0004117v1
2000-05-02
Gravity-driven Dense Granular Flows
We report and analyze the results of numerical studies of dense granular flows in two and three dimensions, using both linear damped springs and Hertzian force laws between particles. Chute flow generically produces a constant density profile that satisfies scaling relations suggestive of a Bagnold grain inertia regime...
0005051v1