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2019-05-20
Quantum parameter-estimation of frequency and damping of a harmonic-oscillator
We determine the quantum Cram\'er-Rao bound for the precision with which the oscillator frequency and damping constant of a damped quantum harmonic oscillator in an arbitrary Gaussian state can be estimated. This goes beyond standard quantum parameter estimation of a single mode Gaussian state for which typically a mod...
1905.08288v1
2019-11-08
Giant anisotropy of Gilbert damping in a Rashba honeycomb antiferromagnet
Giant Gilbert damping anisotropy is identified as a signature of strong Rashba spin-orbit coupling in a two-dimensional antiferromagnet on a honeycomb lattice. The phenomenon originates in spin-orbit induced splitting of conduction electron subbands that strongly suppresses certain spin-flip processes. As a result, the...
1911.03408v1
2020-03-25
Sharp ultimate velocity bounds for the general solution of some linear second order evolution equation with damping and bounded forcing
We consider a class of linear second order differential equations with damping and external force. We investigate the link between a uniform bound on the forcing term and the corresponding ultimate bound on the velocity of solutions, and we study the dependence of that bound on the damping and on the "elastic force". ...
2003.11579v1
2020-08-18
Survey of 360$^{\circ}$ domain walls in magnetic heterostructures: topology, chirality and current-driven dynamics
Chirality and current-driven dynamics of topologically nontrivial 360$^{\circ}$ domain walls (360DWs) in magnetic heterostructures (MHs) are systematically investigated. For MHs with normal substrates, the static 360DWs are N\'{e}el-type with no chirality. While for those with heavy-metal substrates, the interfacial Dz...
2008.08196v1
2021-11-26
Transition from order to chaos in reduced quantum dynamics
We study a damped kicked top dynamics of a large number of qubits ($N \rightarrow \infty$) and focus on an evolution of a reduced single-qubit subsystem. Each subsystem is subjected to the amplitude damping channel controlled by the damping constant $r\in [0,1]$, which plays the role of the single control parameter. In...
2111.13477v1
2022-01-12
Local Well-Posedness of the Gravity-Capillary Water Waves System in the Presence of Geometry and Damping
We consider the gravity-capillary water waves problem in a domain $\Omega_t \subset \mathbb{T} \times \mathbb{R}$ with substantial geometric features. Namely, we consider a variable bottom, smooth obstacles in the flow and a constant background current. We utilize a vortex sheet model introduced by Ambrose, et. al. in ...
2201.04713v2
2023-05-09
Lifespan estimates for semilinear damped wave equation in a two-dimensional exterior domain
Lifespan estimates for semilinear damped wave equations of the form $\partial_t^2u-\Delta u+\partial_tu=|u|^p$ in a two dimensional exterior domain endowed with the Dirichlet boundary condition are dealt with. For the critical case of the semilinear heat equation $\partial_tv-\Delta v=v^2$ with the Dirichlet boundary c...
2305.05124v1
2023-09-25
Linearly implicit exponential integrators for damped Hamiltonian PDEs
Structure-preserving linearly implicit exponential integrators are constructed for Hamiltonian partial differential equations with linear constant damping. Linearly implicit integrators are derived by polarizing the polynomial terms of the Hamiltonian function and portioning out the nonlinearly of consecutive time step...
2309.14184v2
2024-03-10
Linear-in-temperature resistivity and Planckian dissipation arise in a stochastic quantization model of Cooper pairs
We suppose that a Cooper pair (CP) will experience a damping force exerted by the condensed matter. A Langevin equation of a CP in two dimensional condensed matter is established. Following a method similar to Nelson's stochastic mechanics, generalized Schr\"{o}dinger equation of a CP in condensed matter is derived. If...
2403.09710v1
2018-07-31
Comparative study of methodologies to compute the intrinsic Gilbert damping: interrelations, validity and physical consequences
Relaxation effects are of primary importance in the description of magnetic excitations, leading to a myriad of methods addressing the phenomenological damping parameters. In this work, we consider several well-established forms of calculating the intrinsic Gilbert damping within a unified theoretical framework, mappin...
1807.11808v3
2019-11-05
Observation of Nanoscale Opto-Mechanical Molecular Damping; Origin of Spectroscopic Contrast in Photo Induced Force Microscopy
We experimentally investigated the contrast mechanism of infrared photoinduced force microscopy (PiFM) for recording vibrational resonances. Extensive experiments have demonstrated that spectroscopic contrast in PiFM is mediated by opto-mechanical damping of the cantilever oscillation as the optical wavelength is scann...
1911.05190v1
2024-03-28
Constants of Motion for Conserved and Non-conserved Dynamics
This paper begins with a dynamical model that was obtained by applying a machine learning technique (FJet) to time-series data; this dynamical model is then analyzed with Lie symmetry techniques to obtain constants of motion. This analysis is performed on both the conserved and non-conserved cases of the 1D and 2D harm...
2403.19418v1
2003-06-30
Damped oscillatory integrals and boundedness of maximal operators associated to mixed homogeneous hypersurfaces
We study the boundedness problem for maximal operators in 3-dimensional Euclidean space associated to hypersurfaces given as the graph of $c+f$, where $f$ is a mixed homogeneous function which is smooth away from the origin and $c$ is a constant. Our result generalizes a corresponding theorem on mixed homogeneous polyn...
0306429v1
2005-07-26
On simulations of the classical harmonic oscillator equation by difference equations
We show that any second order linear ordinary diffrential equation with constant coefficients (including the damped and undumped harmonic oscillator equation) admits an exact discretization, i.e., there exists a difference equation whose solutions exactly coincide with solutions of the corresponding differential equati...
0507182v1
2012-09-08
Evidence for anisotropic polar nanoregions in relaxor PMN: A neutron study of the elastic constants and anomalous TA phonon damping
We use neutron scattering to characterize the acoustic phonons in the relaxor PMN and demonstrate the presence of an anisotropic damping mechanism directly related to short-range, polar correlations. For a large range of temperatures above Tc ~ 210, K, where dynamic polar correlations exist, acoustic phonons propagatin...
1209.1736v1
2015-11-12
Global weak solutions to 3D compressible Navier-Stokes-Poisson equations with density-dependent viscosity
Global-in-time weak solutions to the Compressible Navier-Stokes-Poisson equations in a three-dimensional torus for large data are considered in this paper. The system takes into account density-dependent viscosity and non-monotone presseur. We prove the existence of global weak solutions to NSP equations with damping t...
1511.03841v1
2015-12-03
Lieb-Thirring inequalities on the torus
We consider the Lieb-Thirring inequalities on the d-dimensional torus with arbitrary periods. In the space of functions with zero average with respect to the shortest coordinate we prove the Lieb-Thirring inequalities for the $\gamma$-moments of the negative eigenvalues with constants independent of ratio of the period...
1512.01160v1
2017-09-24
Exceptional points in two simple textbook examples
We propose to introduce the concept of exceptional points in intermediate courses on mathematics and classical mechanics by means of simple textbook examples. The first one is an ordinary second-order differential equation with constant coefficients. The second one is the well known damped harmonic oscillator. They ena...
1710.00067v1
2021-07-21
Convergence rates for the Heavy-Ball continuous dynamics for non-convex optimization, under Polyak-Łojasiewicz condition
We study convergence of the trajectories of the Heavy Ball dynamical system, with constant damping coefficient, in the framework of convex and non-convex smooth optimization. By using the Polyak-{\L}ojasiewicz condition, we derive new linear convergence rates for the associated trajectory, in terms of objective functio...
2107.10123v2
2022-05-06
Quaternion-based attitude stabilization via discrete-time IDA-PBC
In this paper, we propose a new sampled-data controller for stabilization of the attitude dynamics at a desired constant configuration. The design is based on discrete-time interconnection and damping assignment (IDA) passivity-based control (PBC) and the recently proposed Hamiltonian representation of discrete-time no...
2205.03086v1
2024-04-03
Comment on "Machine learning conservation laws from differential equations"
In lieu of abstract, first paragraph reads: Six months after the author derived a constant of motion for a 1D damped harmonic oscillator [1], a similar result appeared by Liu, Madhavan, and Tegmark [2, 3], without citing the author. However, their derivation contained six serious errors, causing both their method and r...
2404.02896v1
2003-03-13
Vibrational sidebands and dissipative tunneling in molecular transistors
Transport through molecular devices with strong coupling to a single vibrational mode is considered in the case where the vibration is damped by coupling to the environment. We focus on the weak tunneling limit, for which a rate equation approach is valid. The role of the environment can be characterized by a frictiona...
0303236v3
2001-01-16
Nonlinear Landau damping of a plasmino in the quark-gluon plasma
On the basis of the Blaizot-Iancu equations, which are a local formulation of the hard thermal loop (HTL) equations of motion for soft fluctuating quark and gluon fields and their induced sources, the coupled kinetic equations for plasminos and plasmons are obtained. The equality of matrix elements for nonlinear scatte...
0101167v2
2005-10-21
Non-contact atomic force microscopy: Stability criterion and dynamical responses of the shift of frequency and damping signal
The aim of this article is to provide a complete analysis of the behavior of a noncontact atomic force microscope (NC-AFM). We start with a review of the equations of motion of a tip interacting with a surface in which the stability conditions are first revisited for tapping mode. Adding the equations of automatic gain...
0510192v1
2008-06-09
Relaxation Time and Relaxation Function of Quark-Gluon Plasma with Lattice QCD
We propose a method which enables a QCD-based calculation of a relaxation time for a dissipative current in the causal and dissipative hydrodynamic equation derived by Israel and Stewart. We point out that the Israel-Stewart equation is not unique as a causal and dissipative hydrodynamic equation, and the form of the c...
0806.1481v1
2018-02-18
On energy stable discontinuous Galerkin spectral element approximations of the perfectly matched layer for the wave equation
We develop a provably energy stable discontinuous Galerkin spectral element method (DGSEM) approximation of the perfectly matched layer (PML) for the three and two space dimensional (3D and 2D) linear acoustic wave equations, in first order form, subject to well-posed linear boundary conditions. First, using the well-k...
1802.06388v1
2018-11-15
Damping rate of a fermion in ultradegenerate chiral matter
We compute the damping rate of a fermion propagating in a chiral plasma when there is an imbalance between the densities of left- and right-handed fermions, after generalizing the hard thermal loop resummation techniques for these systems. In the ultradegenerate limit, for very high energies the damping rate of this ex...
1811.06394v3
2020-07-19
Global existence and convergence to the modified Barenblatt solution for the compressible Euler equations with physical vacuum and time-dependent damping
In this paper, the smooth solution of the physical vacuum problem for the one dimensional compressible Euler equations with time-dependent damping is considered. Near the vacuum boundary, the sound speed is $C^{1/2}$-H\"{o}lder continuous. The coefficient of the damping depends on time, given by this form $\frac{\mu}{(...
2007.14802v2
2020-11-16
Thresholds for loss of Landau damping in longitudinal plane
Landau damping mechanism plays a crucial role in providing single-bunch stability in LHC, High-Luminosity LHC, other existing as well as previous and future (like FCC) circular hadron accelerators. In this paper, the thresholds for the loss of Landau damping (LLD) in the longitudinal plane are derived analytically usin...
2011.07985v1
2021-11-15
Convergence Analysis of A Second-order Accurate, Linear Numerical Scheme for The Landau-Lifshitz Equation with Large Damping Parameters
A second order accurate, linear numerical method is analyzed for the Landau-Lifshitz equation with large damping parameters. This equation describes the dynamics of magnetization, with a non-convexity constraint of unit length of the magnetization. The numerical method is based on the second-order backward differentiat...
2111.07537v1
2005-05-11
Social Behaviour of Agents: Capital Markets and Their Small Perturbations
We study social behaviour of agents on capital markets when these are perturbed by small perturbations. We use the mean field method. Social behaviour of agents on capital markets is described: volatility of the market, aversion constant and equilibrium states are discussed. Relaxation behaviour of agents on the capita...
0505086v2
2017-06-18
Diffusion constant of slowly rotating black three-brane
In this paper, we take the slowly rotating black three-brane background and perturb it by introducing a vector gauge field. We find the components of the gauge field through Maxwell equations and Bianchi identities. Using currents and some ansatz we find Fick's first law at long wavelength regime. An interesting result...
1706.05669v2
2023-04-24
On elastic constants of zero-temperature amorphous solids
Elastic constants of zero-temperature amorphous solids are given as the difference between the Born term, which results from a hypothetical affine deformation of an amorphous solid, and a correction term which originates from the fact that the deformation of an amorphous solid due to an applied stress is, at the micros...
2304.12374v1
2003-08-24
Numerical analysis of quasinormal modes in nearly extremal Schwarzschild-de Sitter spacetimes
We calculate high-order quasinormal modes with large imaginary frequencies for electromagnetic and gravitational perturbations in nearly extremal Schwarzschild-de Sitter spacetimes. Our results show that for low-order quasinormal modes, the analytical approximation formula in the extremal limit derived by Cardoso and L...
0308077v4
2010-12-08
Nonequilibrium dynamics of the Holstein polaron driven by external electric field
This work represents a fundamental study of a Holstein polaron in one dimension driven away from the ground state by a constant electric field. Taking fully into account quantum effects we follow the time-evolution of the system from its ground state as the constant electric field is switched on at t = 0, until it reac...
1012.1716v3
2015-06-23
Resonant absorption of kink magnetohydrodynamic waves by a magnetic twist in coronal loops
There is ample evidence of twisted magnetic structures in the solar corona. This motivates us to consider the magnetic twist as the cause of Alfven frequency continuum in the coronal loops, which can support the resonant absorption as a rapid damping mechanism for the observed coronal kink magnetohydrodynamic (MHD) osc...
1507.02653v4
2002-07-19
Gilbert Damping in Magnetic Multilayers
We study the enhancement of the ferromagnetic relaxation rate in thin films due to the adjacent normal metal layers. Using linear response theory, we derive the dissipative torque produced by the s-d exchange interaction at the ferromagnet-normal metal interface. For a slow precession, the enhancement of Gilbert dampin...
0207471v1
2003-05-21
Magnetoresistive response of a high mobility 2DES under electromagnetic wave excitation
Oscillations of the resistance observed under electromagnetic wave excitation in the high mobility GaAs/AlGaAs 2DES are examined as a function of the radiation frequency and the power, utilizing an empirical lineshape based on exponentially damped sinusoids. The fit-analysis indicates the resistance oscillation frequen...
0305507v2
2005-10-26
Multiple electron-hole scattering effect on quasiparticle properties in a homogeneous electron gas
We present a detailed study of a contribution of the T matrix accounting for multiple scattering between an electron and a hole to the quasiparticle self-energy. This contribution is considered as an additional term to the GW self-energy. The study is based on a variational solution of the T-matrix integral equation wi...
0510684v2
1995-01-03
High temperature QCD and QED with unstable excitations
We consider the partition functions of QCD and QED at high temperature assuming small coupling constants, and present arguments in favor of an improved perturbative expansion in terms of unstable excitations. Our effective propagators are derived from spectral functions with a constant width. These spectral functions d...
9501203v1
2002-06-22
Yank and Hooke's constant group theoretically
We study the second central extension of the (1+1) Aristotle Lie.We find that the first central extension admit four orbits on the dual of second central extension of the (1+1) Aristotle Lie group.The generic orbit is characterised by a Hooke's constant k and a yank y.If the physics of the orbit is studied with respect...
0206038v1
2010-11-21
Regular and chaotic transport of discrete solitons in asymmetric potentials
Ratchet dynamics of topological solitons of the forced and damped discrete double sine-Gordon system are studied. Directed transport occurring both in regular and in chaotic regions of the phase space and its dependence on damping, amplitude and frequency of the driving, asymmetry parameter, coupling constant, has been...
1011.4707v1
2011-07-13
q-damped Oscillator and degenerate roots of constant coefficients q-difference ODE
The classical model of q-damped oscillator is introduced and solved in terms of Jackson q-exponential function for three different cases, under-damped, over-damped and the critical one. It is shown that in all three cases solution is oscillating in time but is unbounded and non-periodic. By q-periodic function modulati...
1107.2518v1
2012-02-07
The Fine Structure Constant and the CMB Damping Scale
The recent measurements of the Cosmic Microwave Background anisotropies at arcminute angular scales performed by the ACT and SPT experiments are probing the damping regime of CMB fluctuations. The analysis of these datasets unexpectedly suggests that the effective number of relativistic degrees of freedom is larger tha...
1202.1476v1
2013-04-24
Finite amplitude inhomogeneous waves in Mooney-Rivlin viscoelastic solids
New exact solutions are exhibited within the framework of finite viscoelasticity. More precisely, the solutions correspond to finite-amplitude, transverse, linearly-polarized, inhomogeneous motions superposed upon a finite homogeneous static deformation. The viscoelastic body is composed of a Mooney-Rivlin viscoelastic...
1304.6748v1
2014-10-02
Investigation of the temperature-dependence of ferromagnetic resonance and spin waves in Co2FeAl0.5Si0.5
Co2FeAl0.5Si0.5 (CFAS) is a Heusler compound that is of interest for spintronics applications, due to its high spin polarization and relatively low Gilbert damping constant. In this study, the behavior of ferromagnetic resonance as a function of temperature was investigated in CFAS, yielding a decreasing trend of dampi...
1410.0439v1
2015-12-02
Flow of colloidal solids and fluids through constrictions: dynamical density functional theory versus simulation
Using both dynamical density functional theory and particle-resolved Brownian dynamics simulations, we explore the flow of two-dimensional colloidal solids and fluids driven through a linear channel with a geometric constriction. The flow is generated by a constant external force acting on all colloids. The initial con...
1512.00751v1
2017-02-14
Electron-nuclear coherent spin oscillations probed by spin dependent recombination
We demonstrate the detection of coherent electron-nuclear spin oscillations related to the hyperfine interaction and revealed by the band-to-band photoluminescence (PL) in zero external magnetic field. On the base of a pump-probe PL experiment we measure, directly in the temporal domain, the hyperfine constant of an el...
1702.04129v1
2017-03-08
System-Theoretic Performance Metrics for Low-Inertia Stability of Power Networks
As bulk synchronous generators in the power grid are replaced by distributed generation interfaced through power electronics, inertia is removed from the system, prompting concerns over grid stability. Different metrics are available for quantifying grid stability and performance; however, no theoretical results are av...
1703.02646v1
2017-03-30
Study of spin pumping in Co thin film vis-a-vis seed and capping layer using ferromagnetic resonance spectroscopy
We investigated the dependence of the seed [Ta/Pt, Ta/Au] and capping [Pt/Ta, Au/Ta] layers on spin pumping effect in the ferromagnetic 3 nm thick Co thin film using ferromagnetic resonance spectroscopy. The data is fitted with Kittel equation to evaluate damping constant and g-factor. A strong dependence of seed and c...
1703.10630v1
2017-05-02
The response of a Unruh-deWitt particle detector in a thin-shell wormhole spacetime
We investigate the transition probability of a Unruh-deWitt particle detector evolving in flat space and in a wormhole spacetime, in various scenarios. In Minkowski space, we look at the response of the detector on trajectories having discontinuities and rapid variations, as well as the effect of finite-time coupling. ...
1705.00890v1
2017-08-11
On the Small Mass Limit of Quantum Brownian Motion with Inhomogeneous Damping and Diffusion
We study the small mass limit (or: the Smoluchowski-Kramers limit) of a class of quantum Brownian motions with inhomogeneous damping and diffusion. For Ohmic bath spectral density with a Lorentz-Drude cutoff, we derive the Heisenberg-Langevin equations for the particle's observables using a quantum stochastic calculus ...
1708.03685v1
2018-10-11
Propagating spin waves in nanometer-thick yttrium iron garnet films: Dependence on wave vector, magnetic field strength and angle
We present a comprehensive investigation of propagating spin waves in nanometer-thick yttrium iron garnet (YIG) films. We use broadband spin-wave spectroscopy with integrated coplanar waveguides (CPWs) and microstrip antennas on top of continuous and patterned YIG films to characterize spin waves with wave vectors up t...
1810.04973v1
2018-10-17
Perpendicularly magnetized YIG films with small Gilbert damping constant and anomalous spin transport properties
The Y3Fe5O12 (YIG) films with perpendicular magnetic anisotropy (PMA) have recently attracted a great deal of attention for spintronics applications. Here, we report the induced PMA in the ultrathin YIG films grown on (Gd2.6Ca0.4)(Ga4.1Mg0.25Zr0.65)O12 (SGGG) substrates by epitaxial strain without preprocessing. Recipr...
1810.07384v2
2023-09-27
Exploring antisymmetric tensor effects on black hole shadows and quasinormal frequencies
This study explores the impact of antisymmetric tensor effects on spherically symmetric black holes, investigating photon spheres, shadows, emission rate and quasinormal frequencies in relation to a parameter which triggers the Lorentz symmetry breaking. We examine these configurations without and with the presence of ...
2309.15778v3
2006-01-11
Ab initio calculations of inelastic losses and optical constants
Ab initio approaches are introduced for calculations of inelastic losses and vibrational damping in core level x-ray and electron spectroscopies. From the dielectric response function we obtain system-dependent self-energies, inelastic mean free paths, and losses due to multiple-electron excitations, while from the dyn...
0601241v1
2006-04-06
Measurement of the complex dielectric constant of a single gold nanoparticle
A differential interference contrast microscopy technique, which employs a photonic crystal fiber as a white-light source, is used to measure both the real and imaginary parts of the complex dielectric constant of single 10 and 15 nm gold nanoparticles over a wavelength range of 480 to 610 nm. Noticeable deviations fro...
0604174v2
1998-03-08
Wormholes in spacetimes with cosmological horizons
A generalisation of the asymptotic wormhole boundary condition for the case of spacetimes with a cosmological horizon is proposed. In particular, we consider de Sitter spacetime with small cosmological constant. The wave functions selected by this proposal are exponentially damped in WKB approximation when the scale fa...
9803029v1
2003-08-01
The pushing force of a propagating electromagnetic wave
The effect of the electrodynamic forces on a charged particle in a propagating plane electromagnetic wave is investigated. First it is pointed out that for constant fields fulfilling the radiation condition there will be an acceleration in the direction of the Poynting vector. When oscillating fields are considered the...
0308007v1
2002-05-20
Selection of Squeezed States via Decoherence
In the framework of Lindblad theory for open quantum systems, we calculate the entropy of a damped quantum harmonic oscillator which is initially in a quasi-free state. The maximally predictable states are identified as those states producing the minimum entropy increase after a long enough time. In general, the states...
0205127v1
2007-12-17
A single-time two-point closure based on fluid particle displacements
A new single-time two-point closure is proposed, in which the equation for the two-point correlation between the displacement of a fluid particle and the velocity allows one to estimate a Lagrangian timescale. This timescale is used to specify the nonlinear damping of triple correlations in the closure. A closed set of...
0712.2496v1
2011-02-14
Non-gaussianity in the strong regime of warm inflation
The bispectrum of scalar mode density perturbations is analysed for the strong regime of warm inflationary models. This analysis generalises previous results by allowing damping terms in the inflaton equation of motion that are dependent on temperature. A significant amount of non-gaussianity emerges with constant (or ...
1102.2833v2
2012-11-15
Bondi accretion onto cosmological black holes
In this paper we investigate a steady accretion within the Einstein-Straus vacuole, in the presence of the cosmological constant. The dark energy damps the mass accretion rate and --- above certain limit --- completely stops the steady accretion onto black holes, which in particular is prohibited in the inflation era a...
1211.3618v2
2015-02-10
Tunable subwavelength strong absorption by graphene wrapped dielectric particles
The optical absorption properties of graphene wrapped dielectric particles have been investigated by using Mie scattering theory and exact multi-scattering method. It is shown that subwavelength strong absorption in infrared spectra can take place in such systems due to the excitation of plasmon resonance in graphene. ...
1502.02913v1
2015-02-25
Barotropic FRW cosmologies with Chiellini damping in comoving time
For non-zero cosmological constant Lambda, we show that the barotropic FRW cosmologies as worked out in the comoving time lead in the radiation-dominated case to scale factors of identical form as for the Chiellini dissipative scale factors in conformal time obtained recently by us in Phys. Lett. A 379 (2015) 882-887. ...
1502.07033v2
2022-01-27
Thermodynamics of the classical spin triangle
The classical spin system consisting of three spins with Heisenberg interaction is an example of a completely integrable mechanical system. In this paper we explicitly calculate thermodynamic quantities as density of states, specific heat, susceptibility and spin autocorrelation functions. These calculations are perfor...
2201.11401v1
2009-10-28
Nonlinear envelope equation and nonlinear Landau damping rate for a driven electron plasma wave
In this paper, we provide a theoretical description, and calculate, the nonlinear frequency shift, group velocity and collionless damping rate, $\nu$, of a driven electron plasma wave (EPW). All these quantities, whose physical content will be discussed, are identified as terms of an envelope equation allowing one to p...
0910.5289v1
2014-10-17
Hunting down systematics in baryon acoustic oscillations after cosmic high noon
Future dark energy experiments will require better and more accurate theoretical predictions for the baryonic acoustic oscillations (BAO) signature in the spectrum of cosmological perturbations. Here, we use large N-body simulations of the \LambdaCDM Planck cosmology to study any possible systematic shifts and damping ...
1410.4684v2
2020-06-08
Hysteretic depinning of a particle in a periodic potential: Phase diagram and criticality
We consider a massive particle driven with a constant force in a periodic potential and subjected to a dissipative friction. As a function of the drive and damping, the phase diagram of this paradigmatic model is well known to present a pinned, a sliding, and a bistable regime separated by three distinct bifurcation li...
2006.04912v2
2021-06-18
Sloshing dynamics of liquid tank with built-in buoys for wave energy harvesting
This paper proposes a novel design of liquid tank with built-in buoys for wave energy harvesting, named the 'sloshing wave energy converter (S-WEC)'. When the tank is oscillated by external loads (such as ocean waves), internal liquid sloshing is activated, and the mechanical energy of sloshing waves can be absorbed by...
2106.10005v1
2017-04-13
Stochastic Gradient Descent as Approximate Bayesian Inference
Stochastic Gradient Descent with a constant learning rate (constant SGD) simulates a Markov chain with a stationary distribution. With this perspective, we derive several new results. (1) We show that constant SGD can be used as an approximate Bayesian posterior inference algorithm. Specifically, we show how to adjust ...
1704.04289v2
2004-04-13
The Fine-structure Constant as a Probe of Chemical Evolution and AGB Nucleosynthesis in Damped Lyman-alpha Systems
Evidence from a large sample of quasar absorption-line spectra in damped Lyman-alpha systems has suggested a possible time variation of the fine structure constant alpha. The most statistically significant portion of this sample involves the comparison of Mg and Fe wavelength shifts using the many-multiplet (MM) method...
0404257v2
2017-12-05
Harnessing Electrical Power from Vortex-Induced Vibration of a Circular Cylinder
The generation of electrical power from Vortex-Induced Vibration (VIV) of a cylinder is investigated numerically. The cylinder is free to oscillate in the direction transverse to the incoming flow. The cylinder is attached to a magnet that can move along the axis of a coil made from conducting wire. The magnet and the ...
1712.01588v1
2023-12-25
IMEX-RK methods for Landau-Lifshitz equation with arbitrary damping
Magnetization dynamics in ferromagnetic materials is modeled by the Landau-Lifshitz (LL) equation, a nonlinear system of partial differential equations. Among the numerical approaches, semi-implicit schemes are widely used in the micromagnetics simulation, due to a nice compromise between accuracy and efficiency. At ea...
2312.15654v1
2006-11-01
Ferromagnetic resonance study of sputtered Co|Ni multilayers
We report on room temperature ferromagnetic resonance (FMR) studies of [$t$ Co$|2t$ Ni]$\times$N sputtered films, where $0.1 \leq t \leq 0.6$ nm. Two series of films were investigated: films with same number of Co$|$Ni bilayer repeats (N=12), and samples in which the overall magnetic layer thickness is kept constant at...
0611027v2
1996-04-10
A Keck HIRES Investigation of the Metal Abundances and Kinematics of the z=2.46 Damped Lya System Toward Q0201+365
We present high resolution ($\approx 8$ \kms) spectra of the QSO Q0201+365 obtained with HIRES, the echelle spectrograph on the 10m W.M. Keck Telescope. Although we identify over $80\%$ of the absorption features and analyze several of the more complex metal-line systems, we focus our analysis on the damped \Lya system...
9604042v1
2005-07-06
The free precession and libration of Mercury
An analysis based on the direct torque equations including tidal dissipation and a viscous core-mantle coupling is used to determine the damping time scales of O(10^5) years for free precession of the spin about the Cassini state and free libration in longitude for Mercury. The core-mantle coupling dominates the dampin...
0507117v1
1994-09-29
Avalanches in the Weakly Driven Frenkel-Kontorova Model
A damped chain of particles with harmonic nearest-neighbor interactions in a spatially periodic, piecewise harmonic potential (Frenkel-Kontorova model) is studied numerically. One end of the chain is pulled slowly which acts as a weak driving mechanism. The numerical study was performed in the limit of infinitely weak ...
9409006v1
2004-12-18
Fluctuations of the Magnetization in Thin Films due to Conduction Electrons
A detailed analysis of damping and noise due to a {\it sd}-interaction in a thin ferromagnetic film sandwiched between two large normal metal layers is carried out. The magnetization is shown to obey in general a non-local equation of motion which differs from the the Gilbert equation and is extended to the non-adiabat...
0412510v1
2009-04-29
Synthetic electric fields and phonon damping in carbon nanotubes and graphene
Smoothly varying lattice strain in graphene affects the Dirac carriers through a synthetic gauge field. When the lattice strain is time dependent, as in connection with phononic excitations, the gauge field becomes time dependent and the synthetic vector potential is also associated with an electric field. We show that...
0904.4660v1
2010-08-12
Dynamical damping terms for symmetry-seeking shift conditions
Suitable gauge conditions are fundamental for stable and accurate numerical-relativity simulations of inspiralling compact binaries. A number of well-studied conditions have been developed over the last decade for both the lapse and the shift and these have been successfully used both in vacuum and non-vacuum spacetime...
1008.2212v2
2011-11-06
The various manifestations of collisionless dissipation in wave propagation
The propagation of an electrostatic wave packet inside a collisionless and initially Maxwellian plasma is always dissipative because of the irreversible acceleration of the electrons by the wave. Then, in the linear regime, the wave packet is Landau damped, so that in the reference frame moving at the group velocity, t...
1111.1391v2
2012-11-14
New algorithm for footstep localization using seismic sensors in an indoor environment
In this study, we consider the use of seismic sensors for footstep localization in indoor environments. A popular strategy of localization is to use the measured differences in arrival times of source signals at multiple pairs of receivers. In the literature, most algorithms that are based on time differences of arriva...
1211.3233v2
2014-05-19
Comparison of micromagnetic parameters of ferromagnetic semiconductors (Ga,Mn)(As,P) and (Ga,Mn)As
We report on the determination of micromagnetic parameters of epilayers of the ferromagnetic semiconductor (Ga,Mn)As, which has easy axis in the sample plane, and (Ga,Mn)(As,P) which has easy axis perpendicular to the sample plane. We use an optical analog of ferromagnetic resonance where the laser-pulse-induced preces...
1405.4677v1
2014-08-20
Josephson junction ratchet: effects of finite capacitances
We study transport in an asymmetric SQUID which is composed of a loop with three capacitively and resistively shunted Josephson junctions: two in series in one arm and the remaining one in the other arm. The loop is threaded by an external magnetic flux and the system is subjected to both a time-periodic and a constant...
1408.4607v1
2015-03-24
Spin dynamics and frequency dependence of magnetic damping study in soft ferromagnetic FeTaC film with a stripe domain structure
Perpendicular magnetic anisotropy (PMA) and low magnetic damping are the key factors for the free layer magnetization switching by spin transfer torque technique in magnetic tunnel junction devices. The magnetization precessional dynamics in soft ferromagnetic FeTaC thin film with a stripe domain structure was explored...
1503.07043v5
2015-09-07
Spectral inequality and resolvent estimate for the bi-Laplace operator
On a compact Riemannian manifold with boundary, we prove a spectral inequality for the bi-Laplace operator in the case of so-called "clamped" boundary conditions , that is, homogeneous Dirichlet and Neumann conditions simultaneously. We also prove a resolvent estimate for the generator of the damped plate semigroup ass...
1509.02098v5
2016-06-29
On the global existence and blowup of smooth solutions to the multi-dimensional compressible Euler equations with time-depending damping
In this paper, we are concerned with the global existence and blowup of smooth solutions to the multi-dimensional compressible Euler equations with time-depending damping \begin{equation*} \partial_t\rho+\operatorname{div}(\rho u)=0, \quad \partial_t(\rho u)+\operatorname{div}\left(\rho u\otimes u+p\,I_d\right)=-\a...
1606.08935v1
2017-02-16
Effects of Landau damping on ion-acoustic solitary waves in a semiclassical plasma
We study the nonlinear propagation of ion-acoustic waves (IAWs) in an unmagnetized collisionless plasma with the effects of electron and ion Landau damping in the weak quantum (semiclassical) regime, i.e., when the typical ion-acoustic (IA) length scale is larger than the thermal de Broglie wavelength. Starting from a ...
1702.05035v2
2017-08-16
Effects of group velocity and multi-plasmon resonances on the modulation of Langmuir waves in a degenerate plasma
We study the nonlinear wave modulation of Langmuir waves (LWs) in a fully degenerate plasma. Using the Wigner-Moyal equation coupled to the Poisson equation and the multiple scale expansion technique, a modified nonlocal nonlinear Schr{\"{o}}dinger (NLS) equation is derived which governs the evolution of LW envelopes i...
1708.04965v3
2020-01-13
Modelling Stochastic Signatures in Classical Pulsators
We consider the impact of stochastic perturbations on otherwise coherent oscillations of classical pulsators. The resulting dynamics are modelled by a driven damped harmonic oscillator subject to either an external or an internal forcing and white noise velocity fluctuations. We characterize the phase and relative ampl...
2001.04558v1
2020-03-03
Linear stability analysis for 2D shear flows near Couette in the isentropic Compressible Euler equations
In this paper, we investigate linear stability properties of the 2D isentropic compressible Euler equations linearized around a shear flow given by a monotone profile, close to the Couette flow, with constant density, in the domain $\mathbb{T}\times \mathbb{R}$. We begin by directly investigating the Couette shear flow...
2003.01694v1
2020-05-27
Role of diffusive surface scattering in nonlocal plasmonics
The recent generalised nonlocal optical response (GNOR) theory for plasmonics is analysed, and its main input parameter, namely the complex hydrodynamic convection-diffusion constant, is quantified in terms of enhanced Landau damping due to diffusive surface scattering of electrons at the surface of the metal. GNOR has...
2005.13218v2
2021-01-28
Vortex-induced Vibrations of a Confined Circular Cylinder for Efficient Flow Power Extraction
A simple method to increase the flow power extraction efficiency of a circular cylinder, undergoing vortex-induced vibration (VIV), by confining it between two parallel plates is proposed. A two-dimensional numerical study was performed on VIV of a circular cylinder inside a parallel plate channel of height H at Reynol...
2101.11803v1
2021-03-26
First-order strong-field QED processes including the damping of particles states
Volkov states are exact solutions of the Dirac equation in the presence of an arbitrary plane wave. Volkov states, as well as free photon states, are not stable in the presence of the background plane-wave field but "decay" as electrons/positrons can emit photons and photons can transform into electron-positron pairs. ...
2103.14637v1
2021-08-11
Numerical investigation of the formation and stability of homogeneous pairs of soft particles in inertial microfluidics
We investigate the formation and stability of a pair of identical soft capsules in channel flow under mild inertia. We employ a combination of the lattice Boltzmann, finite element and immersed boundary methods to simulate the elastic particles in flow. Validation tests show excellent agreement with numerical results o...
2108.05277v1
2021-11-27
Rate of Entropy Production in Stochastic Mechanical Systems
Entropy production in stochastic mechanical systems is examined here with strict bounds on its rate. Stochastic mechanical systems include pure diffusions in Euclidean space or on Lie groups, as well as systems evolving on phase space for which the fluctuation-dissipation theorem applies, i.e., return-to-equilibrium pr...
2111.13930v1
2022-04-20
Ferrimagnet GdFeCo characterization for spin-orbitronics: large field-like and damping-like torques
Spintronics is showing promising results in the search for new materials and effects to reduce energy consumption in information technology. Among these materials, ferrimagnets are of special interest, since they can produce large spin currents that trigger the magnetization dynamics of adjacent layers or even their ow...
2204.09776v1
2022-11-28
Exciting the TTV Phases of Resonant Sub-Neptunes
There are excesses of sub-Neptunes just wide of period commensurabilities like the 3:2 and 2:1, and corresponding deficits narrow of them. Any theory that explains this period ratio structure must also explain the strong transit timing variations (TTVs) observed near resonance. Besides an amplitude and a period, a sinu...
2211.15701v2
2023-01-23
Estimation of turbulent proton and electron heating rates via Landau damping constrained by Parker Solar Probe observations
The heating of ions and electrons due to turbulent dissipation plays a crucial role in the thermodynamics of the solar wind and other plasma environments. Using magnetic field and thermal plasma observations from the first two perihelia of the Parker Solar Probe (PSP), we model the relative heating rates as a function ...
2301.09713v1