publicationDate
stringlengths
1
2.79k
title
stringlengths
1
36.5k
abstract
stringlengths
1
37.3k
id
stringlengths
9
47
2022-07-29
Coordinated control in multi-terminal VSC-HVDC systems to improve transient stability: Impact on electromechanical-oscillation damping
Multi-terminal high-voltage Direct Current technology based on Voltage-Source Converter stations (VSC-MTDC) is expected to be one of the most important contributors to the future of electric power systems. In fact, among other features, it has already been shown how this technology can contribute to improve transient s...
2208.00083v1
2022-08-04
Thermoelastic Damping in MEMS Gyroscopes at High Frequencies
Microelectromechanical systems (MEMS) gyroscopes are widely used, e.g. in modern automotive and consumer applications, and require signal stability and accuracy in rather harsh environmental conditions. In many use cases, device reliability must be guaranteed under large external loads at high frequencies. The sensitiv...
2208.02591v2
2022-08-02
Motion of a parametrically driven damped coplanar double pendulum
We present the results of linear stability of a damped coplanar double pendulum and its non-linear motion, when the point of suspension is vibrated sinusoidally in the vertical direction with amplitude $a$ and frequency $\omega $. A double pendulum has two pairs of Floquet multipliers, which have been calculated for va...
2208.03292v2
2022-08-09
Simultaneous measurements of unstable and stable Alfvén Eigenmodes in JET
In this paper, we report the novel experimental observation of both unstable and stable Toroidicity-induced Alfv\'en Eigenmodes (TAEs) measured simultaneously in a JET tokamak plasma. The three-ion-heating scheme (D-DNBI-3He) is employed to accelerate deuterons to MeV energies, thereby destabilizing TAEs with toroidal ...
2208.05052v1
2022-09-24
Deep Attentive Belief Propagation: Integrating Reasoning and Learning for Solving Constraint Optimization Problems
Belief Propagation (BP) is an important message-passing algorithm for various reasoning tasks over graphical models, including solving the Constraint Optimization Problems (COPs). It has been shown that BP can achieve state-of-the-art performance on various benchmarks by mixing old and new messages before sending the n...
2209.12000v1
2022-12-01
Slack-based tunable damping leads to a trade-off between robustness and efficiency in legged locomotion
Animals run robustly in diverse terrain. This locomotion robustness is puzzling because axon conduction velocity is limited to a few ten meters per second. If reflex loops deliver sensory information with significant delays, one would expect a destabilizing effect on sensorimotor control. Hence, an alternative explanat...
2212.00475v1
2022-12-22
Spin wave dispersion of ultra-low damping hematite ($α\text{-Fe}_2\text{O}_3$) at GHz frequencies
Low magnetic damping and high group velocity of spin waves (SWs) or magnons are two crucial parameters for functional magnonic devices. Magnonics research on signal processing and wave-based computation at GHz frequencies focussed on the artificial ferrimagnetic garnet Y$_3$Fe$_5$O$_{12}$ (YIG) so far. We report on spi...
2212.11887v2
2023-01-19
Magnetoreological spring as element of vibration control system of dynamicly active equipment for biofuel production
The development of vibration protection systems that ensure efficiency and safety in the operation of process equipment and pipelines is one of the main tasks of controlling the dynamic state of machines. One of the effective methods of vibration isolation of the equipment of these installations is the use of vibration...
2301.07911v1
2023-02-19
Collective Quantum Approach to Surface Plasmon Resonance Effect
In this research we present a theory of the surface plasmon resonance (SPR) effect based on the dual length-scale driven damped collective quantum oscillations of the spill-out electrons in plasmonic material surface. The metallic electron excitations are modeled using the Hermitian effective Schr\"{o}dinger-Poisson sy...
2302.13974v1
2023-03-01
Evolution of the eccentricity and inclination of low-mass planets subjected to thermal forces: a numerical study
By means of three dimensional, high resolution hydrodynamical simulations we study the orbital evolution of weakly eccentric or inclined low-mass protoplanets embedded in gaseous discs subject to thermal diffusion. We consider both non-luminous planets, and planets that also experience the radiative feedback from their...
2303.00867v1
2023-03-13
Discriminative sEMG-based features to assess damping ability and interpret activation patterns in lower-limb muscles of ACLR athletes
Objective: The main goal of the athletes who undergo anterior cruciate ligament reconstruction (ACLR) surgery is a successful return-to-sport. At this stage, identifying muscular deficits becomes important. Hence, in this study, three discriminative features based on surface electromyographic signals (sEMG) acquired in...
2303.06954v1
2023-03-28
Search for damped oscillating structures from charged pion electromagnetic form factor data
The damped oscillating structures recently revealed by a three parametric formula from the proton ``effective'' form factor data extracted of the measured total cross section $\sigma^{bare}_{tot}(e^+e^-\to p\bar p)$ still seem to have an unknown origin. The conjectures of their direct manifestation of the quark-gluon s...
2303.16681v1
2023-05-15
Landau damping and the survival threshold
In this paper, we establish the large time asymptotic behavior of solutions to the linearized Vlasov-Poisson system near general spatially homogenous equilibria $\mu(\frac12|v|^2)$ with connected support on the whole space $\RR^3_x \times \RR^3_v$, including those that are non-monotone. The problem can be solved comple...
2305.08672v1
2023-06-04
Large Dynamical Tide Amplitudes from Small Kicks at Pericenter
The effect of dynamical tide ``kicks" on eccentric binary orbits is considered using the orbital mapping method. It is demonstrated that when mode damping is negligible the mode amplitude will generically grow in time for all values of orbital eccentricity and semi-major axis, even for small kicks outside the regime ex...
2306.02382v1
2023-06-16
Damping of MHD Turbulence in A Partially Ionized Medium
The coupling state between ions and neutrals in the interstellar medium plays a key role in the dynamics of magnetohydrodynamic (MHD) turbulence, but is challenging to study numerically. In this work, we investigate the damping of MHD turbulence in a partially ionized medium using 3D two-fluid (ions+neutrals) simulatio...
2306.10010v2
2023-07-24
BGO quenching effect on spectral measurements of cosmic-ray nuclei in DAMPE experiment
The Dark Matter Particle Explorer (DAMPE) is a satellite-borne detector designed to measure high energy cosmic-rays and $\gamma$-rays. As a key sub-detector of DAMPE, the Bismuth Germanium Oxide (BGO) imaging calorimeter is utilized to measure the particle energy with a high resolution. The nonlinear fluorescence respo...
2307.12629v1
2023-08-04
Interplay of space charge, intrabeam scattering and synchrotron radiation in the Compact Linear Collider damping rings
Future ultra-low emittance rings for electron/positron colliders requiring extremely high beam brightness can be limited by collective effects. In this paper, the interplay of effects such as synchrotron radiation, intra-beam scattering (IBS) and space charge in the vicinity of excited betatron resonances is assessed. ...
2308.02196v3
2023-08-04
Nonlinear wave damping by Kelvin-Helmholtz instability induced turbulence
Magnetohydrodynamic kink waves naturally form as a consequence of perturbations to a structured medium, for example transverse oscillations of coronal loops. Linear theory has provided many insights in the evolution of linear oscillations, and results from these models are often applied to infer information about the s...
2308.02217v2
2023-08-10
JWST observations of galaxy damping wings during reionization interpreted with cosmological simulations
Spectra of the highest redshift galaxies taken with JWST are now allowing us to see into the heart of the reionization epoch. Many of these observed galaxies exhibit strong damping wing absorption redward of their Lyman-$\alpha$ emission. These observations have been used to measure the redshift evolution of the neutra...
2308.05800v1
2023-08-23
Dynamics of pinned quantized vortices in superfluid $^4$He in a microelectromechanical oscillator
We numerically studied the vortex dynamics at zero temperature in superfluid $^4$He confined between two parallel rough solid boundaries, one of which oscillates in a shear mode. This study was motivated by the experimental work by Barquist $et$ $al.$ which employed a microelectromechanical systems (MEMS) oscillator op...
2308.11942v2
2023-12-29
Modeling polyelectrolyte hydration from a multi scale polarizable pseudo particle solvent coarse grained approach
We investigate the reliability of simulations of polyelectrolyte systems in aqueous environments, simulations that are performed using an efficient multi scale coarse grained polarizable pseudo-particle particle approach, denoted as pppl, to model the solvent water, whereas the solutes are modeled using a polarizable a...
2312.17580v1
2024-02-19
Global existence for non-homogeneous incompressible inviscid fluids in presence of Ekman pumping
In this paper, we study the global solvability of the density-dependent incompressible Euler equations, supplemented with a damping term of the form $ \mathfrak{D}_{\alpha}^{\gamma}(\rho, u) = \alpha \rho^{\gamma} u $, where $\alpha>0$ and $ \gamma \in \{0,1\} $. To some extent, this system can be seen as a simplified ...
2402.12592v1
2024-02-20
The Fundamental Parameters of Astrophysical Plasma Turbulence and its Dissipation: Nonrelativistic Limit
A specific set of dimensionless plasma and turbulence parameters is introduced to characterize the nature of turbulence and its dissipation in weakly collisional space and astrophysical plasmas. Key considerations are discussed for the development of predictive models of the turbulent plasma heating that characterize t...
2402.12829v1
2024-03-06
Universality of pseudo-Goldstone damping near critical points
Recently, in studies of holographic models and hydrodynamics with spontaneous breaking of approximate symmetries, it has been proposed that the damping of pseudo-Goldstone modes at finite temperatures is universally constrained in the way that $\Omega_{\varphi}/m_{\varphi}^2\simeq D_{\varphi}$ in the broken phase, wher...
2403.03503v2
1993-11-17
Early Reionization in Cosmology
The cosmic microwave background (CMB) anisotropies have turned out to represent one of the most stringent 'bottle necks' for scenarios of large scale structure formation. As a possibility to relax this constraint, it has been proposed that early reionization can damp CMB fluctuations on small scales due to photon diffu...
9311039v1
1994-08-18
The Damping and Excitation of Galactic Warps by Dynamical Friction
We investigate the dynamical interaction of galactic warps with the surrounding dark matter halo, using analytic perturbation theory. A precessing warp induces a density wake in the collisionless dark matter, which acts back on the original warp, transferring energy and angular momentum between the warp and halo (dynam...
9408068v1
1995-09-14
Another Look at Gaussian Isocurvature Hot Dark Matter Models For Large- Scale Structure
We examine Gaussian isocurvature hot dark matter (massive neutrino) models for large-scale structure in which the initial density perturbations are produced in the baryons with a power--law spectrum $P_B(k) = Ak^{n_B}$. We calculate the linearly-evolved power spectrum and cosmic microwave fluctuations. We find that mod...
9509075v1
1995-10-16
Star Formation and Chemical Evolution in Damped Lya Clouds
Using the redshift evolution of the neutral hydrogen density, as inferred from observations of damped Ly$\alpha$ clouds, we calculate the evolution of star formation rates and elemental abundances in the universe. For most observables our calculations are in rough agreement with previous results based on the instantane...
9510078v1
1995-12-12
A radio Search for high redshift HI absorption
Ground based optical observations have yielded considerable information on the statistics of damped-lyman alpha systems. In particular these systems are known to be the dominant repository of the observed neutral gas at high redshift. However, particularly at high redshift, there is the possibility that optical observa...
9512069v1
1996-01-26
The chemical evolution of galaxies at high redshift
Observations of absorption lines in the spectra of distant QSOs offer a new approach for tracking the evolution of normal galaxies from early epochs to the present day. The damped Ly alpha systems are particularly suitable for measuring the properties of what are likely to be the progenitors of present-day luminous gal...
9601153v1
1996-07-23
A damped Ly-alpha candidate at z~0.1 toward Q 0439-433
We report on the detection of a z_gal=0.101 galaxy projected on the sky at 4.2 arcsec (or 5.2 h^{-1} kpc for q_o=0.5) from the quasar Q 0439-433 (z_em=0.594). The HST spectrum of the quasar shows strong MgII, FeII, SiII, AlII and CIV absorption lines at the same redshift as the galaxy. The equivalent width ratios of th...
9607111v2
1997-08-11
Dynamos with different formulations of a dynamic alpha-effect
We investigate the behaviour of $\alpha\Omega$ dynamos with a dynamic $\alpha$, whose evolution is governed by the imbalance between a driving and a damping term. We focus on truncated versions of such dynamo models which are often studied in connection with solar and stellar variability. Given the approximate nature o...
9708093v1
1997-11-20
ORT observations of the damped Lyman alpha system towards PKS 0201+113
We report a deep radio search with the Ooty Radio Telescope (ORT) for the redshifted 21 cm absorption line from the damped Lyman alpha system seen at redshift 3.388 against the quasar PKS 0201+113. This is currently the most distant system for which a detection of 21 cm absorption has been claimed. The present observat...
9711234v1
1998-01-28
Dynamical Tide in Solar-Type Binaries
Circularization of late-type main-sequence binaries is usually attributed to turbulent convection, while that of early-type binaries is explained by resonant excitation of g modes. We show that the latter mechanism operates in solar-type stars also and is at least as effective as convection, despite inefficient damping...
9801289v1
1998-02-06
Acoustic oscillations and viscosity
Using a simple thermo-hydrodynamic model that respects relativistic causality, we revisit the analysis of qualitative features of acoustic oscillations in the photon-baryon fluid. The growing photon mean free path introduces transient effects that can be modelled by the causal generalization of relativistic Navier-Stok...
9802074v2
2000-02-29
Metallicity Evolution in the Early Universe
Observations of the damped Lya systems provide direct measurements on the chemical enrichment history of neutral gas in the early universe. In this Letter, we present new measurements for four damped Lya systems at high redshift. Combining these data with [Fe/H] values culled from the literature, we investigate the met...
0002513v3
2000-06-02
Surveys for z > 3 Damped Lyman-alpha Absorption Systems
We have completed spectroscopic observations using LRIS on the Keck 1 telescope of 30 very high redshift quasars, 11 selected for the presence of damped Ly-alpha absorption systems and 19 with redshifts z > 3.5 not previously surveyed for absorption systems. We have surveyed an additional 10 QSOs with the Lick 120'' an...
0006044v1
2000-06-21
Constraints on the physical properties of the damped Ly-alpha system of Q0000-2619 at z = 3.054
We present the detection of CII and CII* absorption in the z = 3.0543 damped Ly-alpha system toward Q0000-2619. The derived population ratio implies a fine structure excitation temperature between 19.6 and 21.6 K. The upper value sets a strict upper limit on the CMB temperature at this redshift, which is consistent wit...
0006308v1
2001-04-10
Damping scales of neutralino cold dark matter
The lightest supersymmetric particle, most likely the neutralino, might account for a large fraction of dark matter in the Universe. We show that the primordial spectrum of density fluctuations in neutralino cold dark matter (CDM) has a sharp cut-off due to two damping mechanisms: collisional damping during the kinetic...
0104173v2
2002-05-15
Building the bridge between Damped Ly-alpha Absorbers and Lyman Break galaxies
In 2000, we started the program ``Building the Bridge between Damped Ly-alpha Absorbers and Lyman-Break Galaxies: Ly-alpha Selection of Galaxies'' at the European Southern Observatory's Very Large Telescope. This project is an attempt to use Ly-alpha selection of high-z galaxies to bridge the gap between absorption- an...
0205234v2
2002-05-23
Constraining the strength of Dark Matter Interactions from Structure Formation
We discuss the damping of primordial dark matter fluctuations, taking into account explicitly the interactions of dark matter - whatever their intensity - both with itself and with other particle species. Relying on a general classification of dark matter particle candidates, our analysis provides, from structure forma...
0205406v1
2002-06-06
A catalogue of damped Lyman alpha absorption systems and radio flux densities of the background quasars
We present a catalogue of the 322 damped Lyman alpha absorbers taken from the literature. All damped Lyman alpha absorbers are included, with no selection on redshift or quasar magnitude. Of these, 123 are candidates and await confirmation using high resolution spectroscopy. For all 322 objects we catalogue the radio p...
0206091v1
2002-11-14
Formation of small-scale structure in SUSY CDM
The lightest supersymmetric particle, most likely the lightest neutralino, is one of the most prominent particle candidates for cold dark matter (CDM). We show that the primordial spectrum of density fluctuations in neutralino CDM has a sharp cut-off, induced by two different damping mechanisms. During the kinetic deco...
0211325v1
2002-12-09
Galaxies at z=3 around Damped Ly-alpha Clouds
We are exploring the connection between damped Ly-alpha absorbers (DLAs) and Lyman break galaxies (LBGs) using deep -- (5sigma)=26 m_{AB}-- broad band imaging (UBVI) of four wide fields (0.25 sq. deg. each) obtained at the Kitt Peak 4-m telescope with MOSAIC. Each field contains a damped system at z=3. We want to add...
0212206v1
2003-04-16
Building Blocks in Hierarchical Clustering Scenarios and their Connection with Damped Ly$α$ Systems
We carried out a comprehensive analysis of the chemical properties of the interstellar medium (ISM) and the stellar population (SP) of current normal galaxies and their progenitors in a hierarchical clustering scenario. We compared the results with observations of Damped Lyman-$\alpha$ systems (DLAs) under the hypothes...
0304303v2
2003-05-16
The ESI/KeckII Damped Lya Abundance Database
This paper presents chemical abundance measurements for 37 damped Lya systems at z>2.5 observed with the Echellette Spectrograph and Imager on the KeckII telescope. We measure the HI column densities of these damped systems through Voigt profile fits to their Lya profiles and we implement the apparent optical depth met...
0305312v1
2003-10-28
Chemical Abundances in the Damped Lya Systems
I introduce and review the data and analysis techniques used to measure abundances in the damped Lya systems, quasar absorption-line systems associated with galaxies in the early Universe. The observations and issues associated with their abundance analysis are very similar to those of the Milky Way's interstellar medi...
0310814v1
2004-08-10
Cosmic Ray Scattering and Streaming in Compressible Magnetohydrodynamic Turbulence
Recent advances in understanding of magnetohydrodynamic (MHD) turbulence call for revisions in the picture of cosmic ray transport. In this paper we use recently obtained scaling laws for MHD modes to obtain the scattering frequency for cosmic rays. Using quasilinear theory we calculate gyroresonance with MHD modes (Al...
0408172v1
2004-12-14
Radiative Effects on Particle Acceleration in Electromagnetic Dominated Outflows
Plasma outflows from gamma-ray bursts (GRB), pulsar winds, relativistic jets, and ultra-intense laser targets radiate high energy photons. However, radiation damping is ignored in conventional PIC simulations. In this letter, we study the radiation damping effect on particle acceleration via Poynting fluxes in two-and-...
0412310v3
2005-09-16
Damped Lyman alpha Systems
Observations of damped Lyman alpha systems offer a unique window on the neutral-gas reservoirs that gave rise to galaxies at high redshifts. This review focuses on critical properties such as the H I and metal content of the gas and on independent evidence for star formation. Together, these provide an emerging picture...
0509481v2
2005-11-11
Oscillation mode lifetimes in ksi Hydrae: Will strong mode damping limit asteroseismology of red giant stars?
We introduce a new method to measure frequency separations and mode lifetimes of stochastically excited and damped oscillations, so-called solar-like oscillations. Our method shows that velocity data of the red giant star ksi Hya (Frandsen et al. 2002) support a large frequency separation between modes of roughly 7 mic...
0511344v1
1996-12-14
Nonlinear Landau damping in collisionless plasma and inviscid fluid
The evolution of an initial perturbation in Vlasov plasma is studied in the intrinsically nonlinear long-time limit dominated by the effects of particle trapping. After the possible transient linear exponential Landau damping, the evolution enters into a universal regime with an algebraically damped electric field, $E\...
9612021v1
1998-03-05
On how a joint interaction of two innocent partners (smooth advection & linear damping) produces a strong intermittency
Forced advection of passive scalar by a smooth $d$-dimensional incompressible velocity in the presence of a linear damping is studied. Acting separately advection and dumping do not lead to an essential intermittency of the steady scalar statistics, while being mixed together produce a very strong non-Gaussianity in th...
9803007v1
1999-02-05
Nonlinear Dynamics of A Damped Magnetic Oscillator
We consider a damped magnetic oscillator, consisting of a permanent magnet in a periodically oscillating magnetic field. A detailed investigation of the dynamics of this dissipative magnetic system is made by varying the field amplitude $A$. As $A$ is increased, the damped magnetic oscillator, albeit simple looking, ex...
9902005v1
1996-09-03
Mode damping in a commensurate monolayer solid
The normal modes of a commensurate monolayer solid may be damped by mixing with elastic waves of the substrate. This was shown by B. Hall et al., Phys. Rev. B 32, 4932 (1985), for perpendicular adsorbate vibrations in the presence of an isotropic elastic medium. That work is generalized with an elastic continuum theory...
9609032v1
1997-12-08
Collective oscillations in superconductors revisited
In the recent paper Ohashi and Takada (OT) made statements that in the clean limit considered by us (AV) in 1975, weakly damped collective oscillations in superconductors do not exist due to the Landau damping and their spectrum differs from that obtained in AV. In this Comment we would like to note that these statemen...
9712086v1
1999-01-11
Vortex motion in superconducting YBCO inferred from the damping of the oscillations of a levitating magnetic microsphere
The damping of the oscillations of a small permanent magnet (spherical shape, radius 0.1 mm) levitating between two parallel YBCO surfaces is measured as a function of oscillation amplitude and temperature. The losses in the samples (epitaxial thin films, bulk granular and bulk melt-textured) are analyzed in terms of o...
9901085v1
1999-10-07
On the relative positions of the $2Δ$ peaks in Raman and tunneling spectra of d-wave superconductors
We study $B_{1g}$ Raman intensity $R(\Omega)$ and the density of states $N(\omega)$ in isotropic 2D d-wave superconductors. For an ideal gas, $R(\Omega)$ and $N(\omega)$ have sharp peaks at $\Omega =2\Delta$ and $\omega =\Delta$, respectively, where $\Delta$ is the maximum value of the gap. We study how the peak posi...
9910090v1
1999-11-22
Two-fluid hydrodynamics of a Bose gas including damping from normal fluid transport coefficients
We extend our recent work on the two-fluid hydrodynamics of the condensate and non-condensate in a trapped Bose gas by including the dissipation associated with viscosity and thermal conduction. For purposes of illustration, we consider the hydrodynamic modes in the case of a uniform Bose gas. A finite thermal conducti...
9911336v1
2000-03-31
Kinetic Theory of Collective Excitations and Damping in Bose-Einstein Condensed Gases
We calculate the frequencies and damping rates of the low-lying collective modes of a Bose-Einstein condensed gas at nonzero temperature. We use a complex nonlinear Schr\"odinger equation to determine the dynamics of the condensate atoms, and couple it to a Boltzmann equation for the noncondensate atoms. In this manner...
0003517v1
2000-09-01
The broad Brillouin doublets and central peak of KTaO_3
The incipient ferroelectric KTaO3 presents low-T Brillouin spectra anomalies,e.g. a broad central peak (CP), and some additional Brillouin doublets (BD), whose origin is interpreted in terms of phonon-density fluctuation processes. A parameterisation from new extensive high-resolution neutron-scattering measurements is...
0009012v1
2001-01-15
Temperature Dependence of Damping and Frequency Shifts of the Scissors Mode of a trapped Bose-Einstein Condensate
We have studied the properties of the scissors mode of a trapped Bose-Einstein condensate of $^{87}$Rb atoms at finite temperature. We measured a significant shift in the frequency of the mode below the hydrodynamic limit and a strong dependence of the damping rate as the temperature increased. We compared our damping ...
0101213v2
2001-03-16
Gap Anisotropy and de Haas-van Alphen Effect in Type-II Superconductors
We present a theoretical study on the de Haas-van Alphen (dHvA) oscillation in the vortex state of type-II superconductors, with a special focus on the connection between the gap anisotropy and the oscillation damping. Numerical calculations for three different gap structures clearly indicate that the average gap along...
0103336v3
2001-04-10
Quantum phase transitions and collective modes in d-wave superconductors
Fluctuations near second-order quantum phase transitions in d-wave superconductors can cause strong damping of fermionic excitations, as observed in photoemission experiments. The damping of the gapless nodal quasiparticles can arise naturally in the quantum-critical region of a transition with an additional spin-singl...
0104176v1
2002-04-11
Nonequilibrium relaxation in neutral BCS superconductors: Ginzburg-Landau approach with Landau damping in real time
We present a field-theoretical method to obtain consistently the equations of motion for small amplitude fluctuations of the order parameter directly in real time for a homogeneous, neutral BCS superconductor. This method allows to study the nonequilibrium relaxation of the order parameter as an initial value problem. ...
0204239v2
2002-05-21
Linear spin waves in a trapped Bose gas
An ultra-cold Bose gas of two-level atoms can be thought of as a spin-1/2 Bose gas. It supports spin-wave collective modes due to the exchange mean field. Such collective spin oscillations have been observed in recent experiments at JILA with ${}^{87}$Rb atoms confined in a harmonic trap. We present a theory of the spi...
0205450v1
2002-08-02
Landau damping of transverse quadrupole oscillations of an elongated Bose-Einstein condensate
We study the interaction between low-lying transverse collective oscillations and thermal excitations of an elongated Bose-Einstein condensate by means of perturbation theory. We consider a cylindrically trapped condensate and calculate the transverse elementary excitations at zero temperature by solving the linearized...
0208047v1
2002-08-28
Transverse modes of a cigar-shaped Bose-Einstein condensate
We discuss the collective modes in a harmonically trapped, highly-elongated Bose condensed gas. The transverse breathing mode exhibits a number of interesting features, such as the insensitivity of the condensate mode frequency to the interaction strength, and the closeness of the frequency to that of the non-condensed...
0208567v1
2002-10-31
Stationary quantum statistics of a non-Markovian atom laser
We present a steady state analysis of a quantum-mechanical model of an atom laser. A single-mode atomic trap coupled to a continuum of external modes is driven by a saturable pumping mechanism. In the dilute flux regime, where atom-atom interactions are negligible in the output, we have been able to solve this model wi...
0210688v1
2003-03-23
Damping of micromechanical structures by paramagnetic relaxation
We find that the damping of micromechanical cantilevers is sensitive to the relaxation dynamics of paramagnetic ions contained within the levers. We measure cantilevers containing paramagnetic Mn ions as a function of temperature, magnetic field, and the vibrational mode of the lever and find that the levers damping is...
0303489v1
2003-03-27
Oscillatory wave fronts in chains of coupled nonlinear oscillators
Wave front pinning and propagation in damped chains of coupled oscillators are studied. There are two important thresholds for an applied constant stress $F$: for $|F|<F_{cd}$ (dynamic Peierls stress), wave fronts fail to propagate, for $F_{cd} < |F| < F_{cs}$ stable static and moving wave fronts coexist, and for $|F| ...
0303576v1
2003-06-03
Local Relaxation and Collective Stochastic Dynamics
Damping and thermal fluctuations have been introduced to collective normal modes of a magnetic system in recent modeling of dynamic thermal magnetization processes. The connection between this collective stochastic dynamics and physical local relaxation processes is investigated here. A system of two coupled magnetic g...
0306047v1
2003-07-22
Classical dynamics of a nano-mechanical resonator coupled to a single-electron transistor
We analyze the dynamics of a nano-mechanical resonator coupled to a single-electron transistor (SET) in the regime where the resonator behaves classically. A master equation is derived describing the dynamics of the coupled system which is then used to obtain equations of motion for the average charge state of the SET ...
0307528v1
2003-10-09
Direct measurement of molecular stiffness and damping in confined water layers
We present {\em direct} and {\em linear} measurements of the normal stiffness and damping of a confined, few molecule thick water layer. The measurements were obtained by use of a small amplitude (0.36 $\textrm{\AA}$), off-resonance Atomic Force Microscopy (AFM) technique. We measured stiffness and damping oscillations...
0310219v1
2004-03-08
Mean-field magnetization relaxation in conducting ferromagnets
Collective ferromagnetic motion in a conducting medium is damped by the transfer of the magnetic moment and energy to the itinerant carriers. We present a calculation of the corresponding magnetization relaxation as a linear-response problem for the carrier dynamics in the effective exchange field of the ferromagnet. I...
0403224v2
2004-04-05
Low-temperature specific heat of real crystals: Possibility of leading contribution of optical and short-wavelength acoustical vibrations
We point out that the repeatedly reported glass-like properties of crystalline materials are not necessarily associated with localized (or quasilocalized) excitations. In real crystals, optical and short-wavelength acoustical vibrations remain damped due to defects down to zero temperature. If such a damping is frequen...
0404063v4
2004-04-20
Decoherence processes during active manipulation of excitonic qubits in semiconductor quantum dots
Using photoluminescence spectroscopy, we have investigated the nature of Rabi oscillation damping during active manipulation of excitonic qubits in self-assembled quantum dots. Rabi oscillations were recorded by varying the pulse amplitude for fixed pulse durations between 4 ps and 10 ps. Up to 5 periods are visible, m...
0404465v1
2004-07-29
From subdiffusion to superdiffusion of particles on solid surfaces
We present a numerical and partially analytical study of classical particles obeying a Langevin equation that describes diffusion on a surface modeled by a two dimensional potential. The potential may be either periodic or random. Depending on the potential and the damping, we observe superdiffusion, large-step diffusi...
0407781v1
2004-08-18
Theory of Magnetic Polaron
The concept of magnetic polaron is analysed and developed to elucidate the nature of itinerant charge carrier states in magnetic semiconductors and similar complex magnetic materials. By contrasting the scattering and bound states of carriers within the $s-d$ exchange model, the nature of bound states at finite tempera...
0408404v2
2004-09-27
Dephasing and delay time fluctuations in the chaotic scattering of a quantum particle weakly coupled to a complicated background
Effect of a complicated many-body environment is analyzed on the chaotic motion of a quantum particle in a mesoscopic ballistic structure. The dephasing and absorption phenomena are treated on the same footing in the framework of a schematic microscopic model. The single-particle doorway resonance states excited in the...
0409690v1
2005-01-18
Damping effects and the metal-insulator transition in the two-dimensional electron gas
The damping of single-particle degrees of freedom in strongly correlated two-dimensional Fermi systems is analyzed. Suppression of the scattering amplitude due to the damping effects is shown to play a key role in preserving the validity of the Landau-Migdal quasiparticle picture in a region of a phase transition, asso...
0501427v2
2005-04-17
Dynamics of thermoelastic thin plates: A comparison of four theories
Four distinct theories describing the flexural motion of thermoelastic thin plates are compared. The theories are due to Chadwick, Lagnese and Lions, Simmonds, and Norris. Chadwick's theory requires a 3D spatial equation for the temperature but is considered the most accurate as the others are derivable from it by diff...
0504412v1
2005-04-29
Probing temperature and damping rates in Bose-Einstein condensates using ultraslow light experiments
We propose a method to probe Landau and Beliaev processes in dilute trapped atomic condensates with a multiple state structure using ultraslow light experimental configurations. Under certain conditions, damping rates from these collisional processes are directly proportional to the dephasing rates, making it possible ...
0504784v2
2005-05-23
Anharmonic vs. relaxational sound damping in glasses: I. Brillouin scattering from densified silica
This series discusses the origin of sound damping and dispersion in glasses. In particular, we address the relative importance of anharmonicity versus thermally activated relaxation. In this first article, Brillouin-scattering measurements of permanently densified silica glass are presented. It is found that in this ca...
0505558v3
2005-05-23
Anharmonic vs. relaxational sound damping in glasses: II. Vitreous silica
The temperature dependence of the frequency dispersion in the sound velocity and damping of vitreous silica is reanalyzed. Thermally activated relaxation accounts for the sound attenuation observed above 10 K at sonic and ultrasonic frequencies. Its extrapolation to the hypersonic regime reveals that the anharmonic cou...
0505560v2
2005-06-06
Heat Bath Approach to Landau Damping and Pomeranchuk Quantum Critical Points
We study the problem of the damping of collective modes close to a Pomeranchuk quantum critical point in a Fermi liquid. In analogy with problems in dissipative open quantum systems, we derive the Landau damping of a Fermi liquid by integrating out a macroscopic number of degrees of freedom from a generating functional...
0506146v3
2005-07-01
Measurement of Dissipation of a Three-Level rf SQUID Qubit
The dissipation-induced relaxation (T_1) time of a macroscopic quantum system - a \{lambda}-type three-level rf SQUID flux qubit weakly coupled to control and readout circuitry (CRC) - is investigated via time-domain measurement. The measured interwell relaxation time of the qubit's first excited state, T_1=3.45+/-0.06...
0507008v1
2005-09-19
Interaction effects on magnetooscillations in a two-dimensional electron gas
Motivated by recent experiments, we study the interaction corrections to the damping of magnetooscillations in a two-dimensional electron gas (2DEG). We identify leading contributions to the interaction-induced damping which are induced by corrections to the effective mass and quantum scattering time. The damping facto...
0509463v2
2005-12-20
Damping of zero sound in Luttinger liquids
We calculate the damping gamma_q of collective density oscillations (zero sound) in a one-dimensional Fermi gas with dimensionless forward scattering interaction F and quadratic energy dispersion k^2 / 2 m at zero temperature. For wave-vectors | q| /k_F small compared with F we find to leading order gamma_q = v_F^{-1} ...
0512494v4
2006-04-11
Damping and dispersion of oscillating modes of a multicomponent ionic mixture in a magnetic field
The collective-mode spectrum of a multicomponent magnetized ionic mixture for small wave number k is studied with the use of magnetohydrodynamics and formal kinetic theory. Apart from the usual thermal and diffusive modes, the spectrum contains a set of four oscillating modes. By evaluating the k^2 contributions to the...
0604272v1
2006-05-16
Collective mode damping and viscosity in a 1D unitary Fermi gas
We calculate the damping of the Bogoliubov-Anderson mode in a one-dimensional two-component attractive Fermi gas for arbitrary coupling strength within a quantum hydrodynamic approach. Using the Bethe-Ansatz solution of the 1D BCS-BEC crossover problem, we derive analytic results for the viscosity covering the full ran...
0605413v2
2006-07-06
Low energy theory of a single vortex and electronic quasiparticles in a d-wave superconductor
We highlight the properties of a simple model (contained in our recent work) of the quantum dynamics of a single point vortex interacting with the nodal fermionic quasiparticles of a d-wave superconductor. We describe the renormalization of the vortex motion by the quasiparticles: at T=0, the quasiparticles renormalize...
0607137v2
2005-08-23
Investigations of Process Damping Forces in Metal Cutting
Using finite element software developed for metal cutting by Third Wave Systems we investigate the forces involved in chatter, a self-sustained oscillation of the cutting tool. The phenomena is decomposed into a vibrating tool cutting a flat surface work piece, and motionless tool cutting a work piece with a wavy surfa...
0508102v1
1999-09-27
R-Modes in Superfluid Neutron Stars
The analogs of r-modes in superfluid neutron stars are studied here. These modes, which are governed primarily by the Coriolis force, are identical to their ordinary-fluid counterparts at the lowest order in the small angular-velocity expansion used here. The equations that determine the next order terms are derived an...
9909084v1
2001-02-08
Cyclotron damping and Faraday rotation of gravitational waves
We study the propagation of gravitational waves in a collisionless plasma with an external magnetic field parallel to the direction of propagation. Due to resonant interaction with the plasma particles the gravitational wave experiences cyclotron damping or growth, the latter case being possible if the distribution fun...
0102031v2
2007-02-07
Relativistic r-modes and shear viscosity
We derive the relativistic equations for stellar perturbations, including in a consistent way shear viscosity in the stress-energy tensor, and we numerically integrate our equations in the case of large viscosity. We consider the slow rotation approximation, and we neglect the coupling between polar and axial perturbat...
0702040v1
2000-08-18
Fabrication Process of Rounded Damped Detuned Structure
Following the successful design and fabrication of Damped Detuned Structures (DDS), the JLC/NLC linear collider project advanced to Rounded Damped Detuned Structures (RDDS) with curved cross section of the cavity shape for increased shunt impedance. Various advanced techniques for fabricating RDDS1 disks comparing to t...
0008034v1
2000-08-18
Meeting Tight Frequency Requirement of Rounded Damped Detuned Structure
Following successful design and fabrication of damped detuned structures, the R&D for the accelerating structures of the NLC/JLC linear collider project proceeded to studies of Rounded Damped Detuned Structure with curved cross section of the cavity shape for increased shunt impedance. The important features of the str...
0008035v1
1992-03-16
Comment on ``Damping of energetic gluons and quarks in high-temperature QCD''
Burgess and Marini have recently pointed out that the leading contribution to the damping rate of energetic gluons and quarks in the QCD plasma, given by $\gamma=c g^2\ln(1/g)T$, can be obtained by simple arguments obviating the need of a fully resummed perturbation theory as developed by Braaten and Pisarski. Their ca...
9203211v1
1995-02-16
The Infrared Sensitivity of Screening and Damping in a Quark-Gluon Plasma
All the next-to-leading order contributions to the quasi-particle dispersion laws of a quark-gluon plasma which due to infrared singularities are sensitive to the magnetic-mass scale are calculated using Braaten-Pisarski resummation. These relative-order-$g\ln(g)$ corrections are shown here to generally contribute to t...
9502324v1