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2022-09-21
Asymptotic profile of L^2-norm of solutions for wave equations with critical log-damping
We consider wave equations with a special type of log-fractional damping. We study the Cauchy problem for this model in the whole space, and we obtain an asymptotic profile and optimal estimates of solutions as time goes to infinity in L^2-sense. A maximal discovery of this note is that under the effective damping, in ...
2209.10154v2
2022-09-25
Origin of Immediate Damping of Coherent Oscillations in Photoinduced Charge Density Wave Transition
In stark contrast to the conventional charge density wave (CDW) materials, the one-dimensional CDW on the In/Si(111) surface exhibits immediate damping of the CDW oscillation during the photoinduced phase transition. Here, by successfully reproducing the experimentally observed photoinduced CDW transition on the In/Si(...
2209.12135v1
2022-10-11
QKD in the NISQ era: enhancing secure key rates via quantum error correction
Error mitigation is one of the key challenges in realising the full potential of quantum cryptographic protocols. Consequently, there is a lot of interest in adapting techniques from quantum error correction (QEC) to improve the robustness of quantum cryptographic protocols. In this work, we benchmark the performance o...
2210.05297v1
2022-10-17
Engineering imaginary stark ladder in a dissipative lattice: passive $\mathcal{PT}$ symmetry, K symmetry and localized damping
We study an imaginary stark ladder model and propose a realization of the model in a dissipative chain with linearly increasing site-dependent dissipation strength. Due to the existence of a $K$-symmetry and passive $\mathcal{PT}$ symmetry, the model exhibits quite different feature from its Hermitian counterpart. With...
2210.08725v3
2022-10-18
A quasi-local inhomogeneous dielectric tensor for arbitrary distribution functions
Treatments of plasma waves usually assume homogeneity, but the parallel gradients ubiquitous in plasmas can modify wave propagation and absorption. We derive a quasilocal inhomogeneous correction to the plasma dielectric for arbitrary distributions by expanding the phase correlation integral and develop a novel integra...
2210.10214v1
2022-11-04
On the collisional damping of plasma velocity space instabilities
For plasma velocity space instabilities driven by particle distributions significantly deviated from a Maxwellian, weak collisions can damp the instabilities by an amount that is significantly beyond the collisional rate itself. This is attributed to the dual role of collisions that tend to relax the plasma distributio...
2211.02723v3
2022-11-12
Exponential Stability and exact controllability of a system of coupled wave equations by second order terms (via Laplacian) with only one non-smooth local damping
The purpose of this work is to investigate the exponential stability of a second order coupled wave equations by laplacian with one locally internal viscous damping. Firstly, using a unique continuation theorem combined with a Carleman estimate, we prove that our system is strongly stable without any geometric conditio...
2211.06706v2
2022-11-10
Generalized Bagley-Torvik Equation and Fractional Oscillators
In this paper the Bagley-Torvik Equation is considered with the order of the damping term allowed to range between one and two. The solution is found to be representable as a convolution of trigonometric and exponential functions with the driving force. The properties of the effective decay rate and the oscillation fre...
2211.07575v1
2022-11-21
Lifespan estimates for the compressible Euler equations with damping via Orlicz spaces techniques
In this paper we are interested in the upper bound of the lifespan estimate for the compressible Euler system with time dependent damping and small initial perturbations. We employ some techniques from the blow-up study of nonlinear wave equations. The novelty consists in the introduction of tools from the Orlicz space...
2211.11377v1
2022-11-24
A brief introduction to the mathematics of Landau damping
In these short, rather informal, expository notes I review the current state of the field regarding the mathematics of Landau damping, based on lectures given at the CIRM Research School on Kinetic Theory, November 14--18, 2022. These notes are mainly on Vlasov-Poisson in $(x,v) \in \mathbb T^d \times \mathbb R^d$ howe...
2211.13707v1
2022-12-04
Vibration suppression of a state-of-the-art wafer gripper
In this paper the implementation of piezoelectrics to a state-of-the-art wafer gripper is investigated. The objective is to propose and validate a solution method, which includes a mechanical design and control system, to achieve at least 5% damping for two eigenmodes of a wafer gripper. This objective serves as a 'pro...
2212.01854v1
2022-12-20
Algebra of L-banded Matrices
Convergence is a crucial issue in iterative algorithms. Damping is commonly employed to ensure the convergence of iterative algorithms. The conventional ways of damping are scalar-wise, and either heuristic or empirical. Recently, an analytically optimized vector damping was proposed for memory message-passing (iterati...
2212.12431v3
2023-01-23
Non-Markovianity in the time evolution of open quantum systems assessed by means of quantum state distance
We provide a quantitative evaluation of non-Markovianity (NM) for an XX chain of interacting qubits with one end coupled to a reservoir. The NM of several non-Markovian spectral densities is assessed in terms of various quantum state distance (QSD) measures. Our approach is based on the construction of the density matr...
2301.09323v2
2023-01-26
Optimisation of Power Grid Stability Under Uncertainty
The increased integration of intermittent and decentralised forms of power production has eroded the stability margins of power grids and made it more challenging to ensure reliable and secure power transmission. Reliable grid operation requires system-scale stability in response to perturbations in supply or load; pre...
2301.11215v1
2023-02-11
Uniform stabilization for the semi-linear wave equation with nonlinear Kelvin-Voigt damping
This paper is concerned with the decay estimate of solutions to the semilinear wave equation subject to two localized dampings in a bounded domain. The first one is of the nonlinear Kelvin-Voigt type and is distributed around a neighborhood of the boundary according to the Geometric Control Condition. While the second ...
2302.05667v1
2023-02-20
Exponentially stable breather solutions in nonautonomous dissipative nonlinear Schrödinger lattices
We consider damped and forced discrete nonlinear Schr\"odinger equations on the lattice $\mathbb{Z}$. First we establish the existence of periodic and quasiperiodic breather solutions for periodic and quasiperiodic driving, respectively. Notably, quasiperiodic breathers cannot exist in the system without damping and dr...
2302.09869v2
2023-02-11
Quasinormal modes, Hawking radiation and absorption of the massless scalar field for Bardeen black hole surrounded by perfect fluid dark matter
Bardeen black hole surrounded by perfect fluid dark matter for a massless scalar field. Our result shows that the oscillation frequency of quasinormal modes is enhanced as magnetic charge $g$ or the dark matter parameter $\alpha$ increases. For damping rate of quasinormal modes, the influence of them is different. Spec...
2302.10758v1
2023-02-24
A Numerical Approach for Modeling the Shunt Damping of Thin Panels with Arrays of Separately Piezoelectric Patches
Two-dimensional thin plates are widely used in many aerospace and automotive applications. Among many methods for the attenuation of vibration of these mechanical structures, piezoelectric shunt damping is a promising way. It enables a compact vibration damping method without adding significant mass and volumetric occu...
2302.12525v1
2023-02-27
Enhancing quantum synchronization through homodyne measurement, noise and squeezing
Quantum synchronization has been a central topic in quantum nonlinear dynamics. Despite rapid development in this field, very few have studied how to efficiently boost synchronization. Homodyne measurement emerges as one of the successful candidates for this task, but preferably in the semi-classical regime. In our wor...
2302.13465v2
2023-03-06
Larmor precession in strongly correlated itinerant electron systems
Many-electron systems undergo a collective Larmor precession in the presence of a magnetic field. In a paramagnetic metal, the resulting spin wave provides insight into the correlation effects generated by the electron-electron interaction. Here, we use dynamical mean-field theory to investigate the collective Larmor p...
2303.03468v2
2023-03-19
Asymptotic-preserving finite element analysis of Westervelt-type wave equations
Motivated by numerical modeling of ultrasound waves, we investigate robust conforming finite element discretizations of quasilinear and possibly nonlocal equations of Westervelt type. These wave equations involve either a strong dissipation or damping of fractional-derivative type and we unify them into one class by in...
2303.10743v1
2023-03-31
Measurement of the cosmic p+He energy spectrum from 46 GeV to 316 TeV with the DAMPE space mission
Recent observations of the light component of the cosmic-ray spectrum have revealed unexpected features that motivate further and more precise measurements up to the highest energies. The Dark Matter Particle Explorer (DAMPE) is a satellite-based cosmic-ray experiment that is operational since December 2015, continuous...
2304.00137v4
2023-04-18
Edge-selective extremal damping from topological heritage of dissipative Chern insulators
One of the most important practical hallmarks of topological matter is the presence of topologically protected, exponentially localised edge states at interfaces of regions characterised by unequal topological invariants. Here, we show that even when driven far from their equilibrium ground state, Chern insulators can ...
2304.09040v3
2023-04-25
Weakly damped bosons and precursor gap in the vicinity of an antiferromagnetic metallic transition
We study the electronic spectral function of a metal in the vicinity of an antiferromagnetic (AFM) quantum critical point, focusing on a situation where the bare bandwidth of the spin fluctuations is significantly smaller than the Fermi energy. In this limit, we identify a range of energies where the fermionic quasipar...
2304.12697v1
2023-05-04
Vibrational resonance in a damped and two-frequency driven system of particle on a rotating parabola
In the present work, we examine the role of nonlinearity in vibrational resonance (VR) of a forced and damped form of a velocity-dependent potential system. Many studies have focused on studying the vibrational resonance in different potentials, like bistable potential, asymmetrically deformed potential, and rough pote...
2305.02674v1
2023-05-06
Stochastic wave equation with Hölder noise coefficient: well-posedness and small mass limit
We construct unique martingale solutions to the damped stochastic wave equation $$ \mu \frac{\partial^2u}{\partial t^2}(t,x)=\Delta u(t,x)-\frac{\partial u}{\partial t}(t,x)+b(t,x,u(t,x))+\sigma(t,x,u(t,x))\frac{dW_t}{dt},$$ where $\Delta$ is the Laplacian on $[0,1]$ with Dirichlet boundary condition, $W$ is space-ti...
2305.04068v2
2023-05-08
Information capacity analysis of fully correlated multi-level amplitude damping channels
The primary objective of quantum Shannon theory is to evaluate the capacity of quantum channels. In spite of the existence of rigorous coding theorems that quantify the transmission of information through quantum channels, superadditivity effects limit our understanding of the channel capacities. In this paper, we main...
2305.04481v2
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
2023-05-19
Cold damping of levitated optically coupled nanoparticles
Methods for controlling the motion of single particles, optically levitated in vacuum, have developed rapidly in recent years. The technique of cold damping makes use of feedback-controlled, electrostatic forces to increase dissipation without introducing additional thermal fluctuations. This process has been instrumen...
2305.11809v1
2023-05-25
Damping of three-dimensional waves on coating films dragged by moving substrates
Paints and coatings often feature interfacial defects due to disturbances during the deposition process which, if they persist until solidification, worsen the product quality. In this article, we investigate the stability of a thin liquid film dragged by a vertical substrate moving against gravity, a flow configuratio...
2305.16139v3
2023-06-12
Realizable Eddy Damped Markovian Anisotropic Closure for Turbulence and Rossby Wave Interactions
A realizable Eddy Damped Markovian Anisotropic Closure (EDMAC) is presented for the interaction of two dimensional turbulence and transient waves such as Rossby waves. The structure of the EDMAC ensures that it is as computationally efficient as the Eddy Damped Quasi Normal Markovian (EDQNM) closure but unlike the EDQN...
2306.06921v1
2023-06-18
Partial data inverse problem for hyperbolic equation with time-dependent damping coefficient and potential
We study an inverse problem of determining a time-dependent damping coefficient and potential appearing in the wave equation in a compact Riemannian manifold of dimension three or higher. More specifically, we are concerned with the case of conformally transversally anisotropic manifolds, or in other words, compact Rie...
2306.10442v2
2023-06-26
Blow-up result for a weakly coupled system of wave equations with a scale-invariant damping, mass term and time derivative nonlinearity
We study in this article the blow-up of solutions to a coupled semilinear wave equations which are characterized by linear damping terms in the \textit{scale-invariant regime}, time-derivative nonlinearities, mass terms and Tricomi terms. The latter are specifically of great interest from both physical and mathematical...
2306.14768v1
2023-06-26
Revisiting the damped quantum harmonic oscillator
We reanalyse the quantum damped harmonic oscillator, introducing three less than common features. These are (i) the use of a continuum model of the reservoir rather than an ensemble of discrete oscillators, (ii) an exact diagonalisation of the Hamiltonian by adapting a technique pioneered by Fano, and (iii) the use of ...
2306.15013v1
2023-06-27
SPDER: Semiperiodic Damping-Enabled Object Representation
We present a neural network architecture designed to naturally learn a positional embedding and overcome the spectral bias towards lower frequencies faced by conventional implicit neural representation networks. Our proposed architecture, SPDER, is a simple MLP that uses an activation function composed of a sinusoidal ...
2306.15242v1
2023-07-03
Fast Convergence of Inertial Multiobjective Gradient-like Systems with Asymptotic Vanishing Damping
We present a new gradient-like dynamical system related to unconstrained convex smooth multiobjective optimization which involves inertial effects and asymptotic vanishing damping. To the best of our knowledge, this system is the first inertial gradient-like system for multiobjective optimization problems including asy...
2307.00975v3
2023-07-05
Strong convergence rates for a full discretization of stochastic wave equation with nonlinear damping
The paper establishes the strong convergence rates of a spatio-temporal full discretization of the stochastic wave equation with nonlinear damping in dimension one and two. We discretize the SPDE by applying a spectral Galerkin method in space and a modified implicit exponential Euler scheme in time. The presence of th...
2307.01975v1
2023-07-12
Decoherence effects on lepton number violation from heavy neutrino-antineutrino oscillations
We study decoherence effects and phase corrections in heavy neutrino-antineutrino oscillations (NNOs), based on quantum field theory with external wave packets. Decoherence damps the oscillation pattern, making it harder to resolve experimentally. Additionally, it enhances lepton number violation (LNV) for processes in...
2307.06208v1
2023-07-23
Visco-elastic damped wave models with time-dependent coefficient
In this paper, we study the following Cauchy problem for linear visco-elastic damped wave models with a general time-dependent coefficient $g=g(t)$: \begin{equation} \label{EqAbstract} \tag{$\star$} \begin{cases} u_{tt}- \Delta u + g(t)(-\Delta)u_t=0, &(t,x) \in (0,\infty) \times \mathbb{R}^n, \\ u(0,x)= u_0(x),\quad u...
2307.12340v1
2023-07-24
Phonon damping in a 2D superfluid: insufficiency of Fermi's golden rule at low temperature
It is generally accepted that the phonon gas of a superfluid always enters a weak coupling regime at sufficiently low temperatures, whatever the strength of the interactions between the underlying particles (constitutive of the superfluid). Thus, in this limit, we should always be able to calculate the damping rate of ...
2307.12705v1
2023-08-01
Regularity for the Timoshenko system with fractional damping
We study, the Regularity of the Timoshenko system with two fractional dampings $(-\Delta)^\tau u_t$ and $(-\Delta)^\sigma \psi_t$; both of the parameters $(\tau, \sigma)$ vary in the interval $[0,1]$. We note that ($\tau=0$ or $\sigma=0$) and ($\tau=1$ or $\sigma=1$) the dampings are called frictional and viscous, resp...
2308.00573v2
2023-08-16
Large time asymptotics for partially dissipative hyperbolic systems without Fourier analysis: application to the nonlinearly damped p-system
A new framework to obtain time-decay estimates for partially dissipative hyperbolic systems set on the real line is developed. Under the classical Shizuta-Kawashima (SK) stability condition, equivalent to the Kalman rank condition in control theory, the solutions of these systems decay exponentially in time for high fr...
2308.08280v1
2023-09-06
Effective Description of the Quantum Damped Harmonic Oscillator: Revisiting the Bateman Dual System
In this work, we present a quantization scheme for the damped harmonic oscillator (QDHO) using a framework known as momentous quantum mechanics. Our method relies on a semiclassical dynamical system derived from an extended classical Hamiltonian, where the phase-space variables are given by expectation values of observ...
2309.02689v1
2023-09-09
Secondary cosmic-ray nuclei in the model of Galactic halo with nonlinear Landau damping
We employ our recent model of the cosmic-ray (CR) halo by Chernyshov et al. (2022) to compute the Galactic spectra of stable and unstable secondary nuclei. In this model, confinement of the Galactic CRs is entirely determined by the self-generated Alfvenic turbulence whose spectrum is controlled by nonlinear Landau dam...
2309.04772v1
2023-09-20
On the damping of tidally driven oscillations
Expansions in the oscillation modes of tidally perturbed bodies provide a useful framework for representing tidally induced flows. However, recent work has demonstrated that such expansions produce inaccurate predictions for secular orbital evolution when mode damping rates are computed independently. We explore the co...
2309.11502v1
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
2023-10-12
Plasmon dispersion and Landau damping in the nonlinear quantum regime
We study the dispersion properties of electron plasma waves, or plasmons, which can be excited in quantum plasmas in the nonlinear regime. In order to describe nonlinear electron response to finite amplitude plasmons, we apply the Volkov approach to non-relativistic electrons. For that purpose, we use the Schr\"odinger...
2310.08544v1
2023-10-29
Asymptotic profiles for the Cauchy problem of damped beam equation with two variable coefficients and derivative nonlinearity
In this article we investigate the asymptotic profile of solutions for the Cauchy problem of the nonlinear damped beam equation with two variable coefficients: \[ \partial_t^2 u + b(t) \partial_t u - a(t) \partial_x^2 u + \partial_x^4 u = \partial_x \left( N(\partial_x u) \right). \] In the authors' previous article ...
2310.18878v1
2023-11-09
Landau Damping in an Electron Gas
Material science methods aim at developing efficient computational schemes for describing complex many-body effects and how they are revealed in experimentally measurable properties. Bethe-Salpeter equation in the self-consistent Hartree-Fock basis is often used for this purpose, and in this paper we employ the real-fr...
2311.05611v2
2023-11-11
On asymptotic properties of solutions to $σ$-evolution equations with general double damping
In this paper, we would like to consider the Cauchy problem for semi-linear $\sigma$-evolution equations with double structural damping for any $\sigma\ge 1$. The main purpose of the present work is to not only study the asymptotic profiles of solutions to the corresponding linear equations but also describe large-time...
2311.06660v1
2023-11-14
Enhanced classical radiation damping of electronic cyclotron motion in the vicinity of the Van Hove singularity in a waveguide
We study the damping process of electron cyclotron motion and the resulting emission in a waveguide using the classical Friedrichs model without relying on perturbation analysis such as Fermi's golden rule. A classical Van Hove singularity appears at the lower bound (or cut-off frequency) of the dispersion associated w...
2311.08121v3
2023-11-18
The temperature dependent Boltzmann equation beyond local equilibrium assumption
In this manuscript, we present a temperature dependent Boltzmann equation for the particles transport through a environmental reservoir, where the temperature refers to the equilibrium temperature of reservoir, a new damping force and a inverse damping relaxation time are derived based on the classical Boltzmann equati...
2311.11028v1
2023-12-13
Integrating Superregenerative Principles in a Compact, Power-Efficient NMR/NQR Spectrometer: A Novel Approach with Pulsed Excitation
We present a new approach to Nuclear Quadrupole Resonance (NQR)/Nuclear Magnetic Resonance (NMR) spectroscopy, the Damp-Enhanced Superregenerative Nuclear Spin Analyser (DESSA). This system integrates Superregenerative principles with pulsed sample excitation and detection, offering significant advancements over tradit...
2312.08491v1
2023-12-26
Dynamical polarization function, plasmons, their damping and collective effects in semi-Dirac bands
We have calculated the dynamical polarization, plasmons and damping rates in semi-Dirac bands (SDB's) with zero band gap and half-linear, half-parabolic low-energy spectrum. The obtained plasmon dispersions are strongly anisotropic and demonstrate some crucial features of both two-dimensional electron gas and graphene....
2312.16117v1
2024-01-09
Coherent errors in stabilizer codes caused by quasistatic phase damping
Quantum error correction is a key challenge for the development of practical quantum computers, a direction in which significant experimental progress has been made in recent years. In solid-state qubits, one of the leading information loss mechanisms is dephasing, usually modelled by phase flip errors. Here, we introd...
2401.04530v2
2024-01-19
Composite learning backstepping control with guaranteed exponential stability and robustness
Adaptive backstepping control provides a feasible solution to achieve asymptotic tracking for mismatched uncertain nonlinear systems. However, input-to-state stability depends on high-gain feedback generated by nonlinear damping terms, and closed-loop exponential stability with parameter convergence involves a stringen...
2401.10785v1
2024-01-23
Model-Free $δ$-Policy Iteration Based on Damped Newton Method for Nonlinear Continuous-Time H$\infty$ Tracking Control
This paper presents a {\delta}-PI algorithm which is based on damped Newton method for the H{\infty} tracking control problem of unknown continuous-time nonlinear system. A discounted performance function and an augmented system are used to get the tracking Hamilton-Jacobi-Isaac (HJI) equation. Tracking HJI equation is...
2401.12882v1
2024-01-30
The nonlinear dynamic behavior of a Rubber-Layer Roller Bearing (RLRB) for vibration isolation
In this paper, we study the dynamic behavior of a Rubber-Layer Roller Bearing (RLRB) interposed between a spring-mass elemental superstructure and a vibrating base. Thanks to the viscoelastic rolling contact between the rigid rollers and the rubber layers, the RLRB is able to provide a nonlinear damping behavior. The e...
2401.16880v1
2024-01-30
Poynting-Robertson damping of laser beam driven lightsails
Lightsails using Earth-based lasers for propulsion require passive stabilization to stay within the beam. This can be achieved through the sail's scattering properties, creating optical restoring forces and torques. Undamped restoring forces produce uncontrolled oscillations, which could jeopardize the mission, but it ...
2401.16924v1
2024-02-29
The Equation of Motion for Taut-Line Buzzers
Equations of motion are developed for the oscillatory rotation of a disk suspended between twisted strings kept under tension by a hanging mass, to which additional forces may be applied. In the absence of forcing, damped harmonic oscillations are observed to decay with an exponential time envelope for two different st...
2402.19285v1
2024-03-08
A design methodology for nonlinear oscillator chains enabling energy localization tuning and soliton stability enhancement with optimal damping
In this paper, the vibration energy localization in coupled nonlinear oscillators is investigated, based on the creation of standing solitons. The main objective is to establish a design methodology for mechanical lattices using the Nonlinear Schr\"odinger Equation (NLSE) as a guide strategy, even in the presence of da...
2403.05176v1
2024-03-08
Damping Obliquities of Hot Jupiter Hosts by Resonance Locking
When orbiting hotter stars, hot Jupiters are often highly inclined relative to their host star equator planes. By contrast, hot Jupiters orbiting cooler stars are more aligned. Prior attempts to explain this correlation between stellar obliquity and effective temperature have proven problematic. We show how resonance l...
2403.05616v1
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
1995-10-04
Microlensing By a Prolate All-Macho Halo
It is widely believed that dark matter halos are flattened, that is closer to oblate than prolate. The evidence cited is based largely on observations of galaxies which do not look anything like our own and on numerical simulations which use ad hoc initial conditions. Given what we believe to be a ``reasonable doubt'' ...
9510023v1
1997-04-25
Constraints on the density perturbation spectrum from primordial black holes
We re-examine the constraints on the density perturbation spectrum, including its spectral index $n$, from the production of primordial black holes. The standard cosmology, where the Universe is radiation dominated from the end of inflation up until the recent past, was studied by Carr, Gilbert and Lidsey; we correct t...
9704251v1
1998-02-26
Inversion of polarimetric data from eclipsing binaries
We describe a method for determining the limb polarization and limb darkening of stars in eclipsing binary systems, by inverting photometric and polarimetric light curves. Because of the ill-conditioning of the problem, we use the Backus-Gilbert method to control the resolution and stability of the recovered solution...
9802334v1
1998-09-04
Cluster-Cluster Strong Lensing: Expectations and Detection Methods
We calculate the all-sky number of galaxy clusters that are expected to be gravitationally lensed by foreground massive clusters. We describe the redshift and number distributions of clusters using a Press-Schechter analysis, and model the foreground lensing clusters as singular isothermal spheres. If Omega_m=0.3 and O...
9809062v3
2000-04-14
Source Reconstruction as an Inverse Problem
Inverse Problem techniques offer powerful tools which deal naturally with marginal data and asymmetric or strongly smoothing kernels, in cases where parameter-fitting methods may be used only with some caution. Although they are typically subject to some bias, they can invert data without requiring one to assume a part...
0004200v1
2000-04-18
Galaxy Cluster Baryon Fractions, Cluster Surveys and Cosmology
The properties of nearby galaxy clusters limit the range of cosmological parameters consistent with our universe. We describe the limits which arise from studies of the intracluster medium (ICM) mass fraction fICM and consideration of the possible sources of systematic error: Omega_M<0.44h_{50}^{-1/2} at 95% confidence...
0004244v1
2000-05-11
Measurement of [OIII] Emission in Lyman Break Galaxies
Measurements of [OIII] emission in Lyman Break galaxies (LBGs) at z>3 are presented. Four galaxies were observed with narrow-band filters using the Near-IR Camera on the Keck I 10-m telescope. A fifth galaxy was observed spectroscopically during the commissioning of NIRSPEC, the new infrared spectrometer on Keck II. Th...
0005254v1
2001-03-02
Clusters in the Precision Cosmology Era
Over the coming decade, the observational samples available for studies of cluster abundance evolution will increase from tens to hundreds, or possibly to thousands, of clusters. Here we assess the power of future surveys to determine cosmological parameters. We quantify the statistical differences among cosmologies, i...
0103049v1
2002-07-05
New Tests of the Cluster Entropy Floor Hypothesis
Recent efforts to account for the observed X-ray luminosity - temperature relation of galaxy clusters has led to suggestions that the ICM has an apparent ``entropy floor'' at or above the level of 300 keV cm^2. Here, we propose new tests based on the thermal Sunyaev-Zeldovich effect and on the cluster gas mass - temper...
0207147v1
2003-06-18
Kinematic Masses of Super Star Clusters in M82 from High-Resolution Near-Infrared Spectroscopy
Using high-resolution (R~22,000) near-infrared (1.51 -- 1.75 microns) spectra from Keck Observatory, we measure the kinematic masses of two super star clusters in M82. Cross-correlation of the spectra with template spectra of cool evolved stars gives stellar velocity dispersions of sigma_r=15.9 +/- 0.8 km/s for MGG-9 a...
0306373v1
2003-09-10
The CMB Quadrupole in a Polarized Light
The low quadrupole of the cosmic microwave background (CMB), measured by COBE and confirmed by WMAP, has generated much discussion recently. We point out that the well-known correlation between temperature and polarization anisotropies of the CMB further constrains the low multipole anisotropy data. This correlation or...
0309281v2
2003-10-11
Statistics of Giant Arcs in Galaxy Clusters
We study the expected properties and statistics of giant arcs produced by galaxy clusters in a LambdaCDM universe and investigate how the characteristics of CDM clusters determine the properties of the arcs they generate. Due to the triaxiality and substructure of CDM halos, the giant arc cross section for individual c...
0310306v1
2004-01-23
Gravitational Lensing of the Microwave Background by Galaxy Clusters
Galaxy clusters will distort the pattern of temperature anisotropies in the microwave background via gravitational lensing. We create lensed microwave background maps using clusters drawn from numerical cosmological simulations. A distinctive dipole-like temperature fluctuation pattern is formed aligned with the underl...
0401519v2
2004-04-15
Is the slope of the intrinsic Baldwin effect constant?
We investigate the relationship between emission-line strength and continuum luminosity in the best-studied nearby Seyfert 1 galaxy NGC5548. Our analysis of 13 years of ground-based optical monitoring data reveals significant year-to-year variations in the observed H-beta emission-line response in this source. More spe...
0404296v1
2005-08-04
Gravitino, Axino, Kaluza-Klein Graviton Warm and Mixed Dark Matter and Reionisation
Stable particle dark matter may well originate during the decay of long-lived relic particles, as recently extensively examined in the cases of the axino, gravitino, and higher-dimensional Kaluza-Klein (KK) graviton. It is shown that in much of the viable parameter space such dark matter emerges naturally warm/hot or m...
0508141v2
1999-08-10
Magnetic relaxation in a classical spin chain as model for nanowires
With decreasing particle size, different mechanisms dominate the thermally activated magnetization reversal in ferromagnetic particles. We investigate some of these mechanisms for the case of elongated, single-domain nanoparticles which we describe by a classical Heisenberg spin chain driven by an external magnetic fie...
9908150v1
2000-07-17
Fine-grid Simulations of Thermally Activated Switching in Nanoscale Magets
Numerical integration of the Landau-Lifshitz-Gilbert equation with thermal fluctuations is used to study the dynamic response of single-domain nanomagnets to rapid changes in the applied magnetic field. The simulation can resolve magnetization patterns within nanomagnets and uses the Fast Multipole method to calculate ...
0007279v1
2001-01-31
Langevin Simulation of Thermally Activated Magnetization Reversal in Nanoscale Pillars
Numerical solutions of the Landau-Lifshitz-Gilbert micromagnetic model incorporating thermal fluctuations and dipole-dipole interactions (calculated by the Fast Multipole Method) are presented for systems composed of nanoscale iron pillars of dimension 9 nm x 9 nm x 150 nm. Hysteresis loops generated under sinusoidally...
0101477v2
2001-05-04
On a common circle: natural scenes and Gestalt rules
To understand how the human visual system analyzes images, it is essential to know the structure of the visual environment. In particular, natural images display consistent statistical properties that distinguish them from random luminance distributions. We have studied the geometric regularities of oriented elements (...
0105097v1
2002-10-11
Fluctuations and Dissipation of Coherent Magnetization
A quantum mechanical model is used to derive a generalized Landau-Lifshitz equation for a magnetic moment, including fluctuations and dissipation. The model reproduces the Gilbert-Brown form of the equation in the classical limit. The magnetic moment is linearly coupled to a reservoir of bosonic degrees of freedom. Use...
0210273v2
2002-11-18
Field dependence of magnetization reversal by spin transfer
We analyse the effect of the applied field (Happl) on the current-driven magnetization reversal in pillar-shaped Co/Cu/Co trilayers, where we observe two different types of transition between the parallel (P) and antiparallel (AP) magnetic configurations of the Co layers. If Happl is weaker than a rather small threshol...
0211371v1
2003-10-18
NMR Investigation of the Organic Conductor lambda-(BETS)2FeCl4
The two-dimensional organic conductor lambda-(BETS)2FeCl4 has an unusual phase diagram as a function of temperature and magnetic field that includes a paramagnetic metal (PM) phase, an antiferromagnetic insulating (AFI) phase, and a field-induced superconducting phase [S. Uji, H. Kobayashi, L. Balicas, and James S. Bro...
0310433v1
2004-04-22
Non-collinear magnetic structures: a possible cause for current induced switching
Current induced switching in Co/Cu/Co trilayers is described in terms of ab-initio determined magnetic twisting energies and corresponding sheet resistances. In viewing the twisting energy as an energy flux the characteristic time thereof is evaluated by means of the Landau-Lifshitz-Gilbert equation using ab-initio par...
0404534v1
2004-06-21
Basic considerations for magnetization dynamics in the combined presence of spin-transfer torques and thermal fluctuations
This article reviews basic theoretical features of Gilbert magnetization dynamics of a single domain magnetic film in the presence of Slonczewski spin-transfer torques, with and without thermal fluctuations taken into account. Rather than showing results of detailed numerical calculations, the discussion here is restri...
0406486v1
2004-06-24
Thermal Effects on the Magnetic Field Dependence of Spin Transfer Induced Magnetization Reversal
We have developed a self-aligned, high-yield process to fabricate CPP (current perpendicular to the plane) magnetic sensors of sub 100 nm dimensions. A pinned synthetic antiferromagnet (SAF) is used as the reference layer which minimizes dipole coupling to the free layer and field induced rotation of the reference laye...
0406574v1
2004-07-23
Micromagnetic understanding of current-driven domain wall motion in patterned nanowires
In order to explain recent experiments reporting a motion of magnetic domain walls (DW) in nanowires carrying a current, we propose a modification of the spin transfer torque term in the Landau-Lifchitz-Gilbert equation. We show that it explains, with reasonable parameters, the measured DW velocities as well as the var...
0407628v2
2004-08-07
Hysteresis multicycles in nanomagnet arrays
We predict two new physical effects in arrays of single-domain nanomagnets by performing simulations using a realistic model Hamiltonian and physical parameters. First, we find hysteretic multicycles for such nanomagnets. The simulation uses continuous spin dynamics through the Landau-Lifshitz-Gilbert (LLG) equation. I...
0408158v1
2004-12-03
High frequency magnetic permeability of nanocomposite film
The high frequency magnetic permeability of nanocomposite film consisting of the single-domain spherical ferromagnetic particles in the dielectric matrix is studied. The permeability is assumed to be determined by rotation of the ferromagnetic inclusion magnetic moments around equilibrium direction in AC magnetic field...
0412073v1
2005-01-07
Dielectric resonances of ordered passive arrays
The electrical and optical properties of ordered passive arrays, constituted of inductive and capacitive components, are usually deduced from Kirchhoff's rules. Under the assumption of periodic boundary conditions, comparable results may be obtained via an approach employing transfer matrices. In particular, resonances...
0501137v1
2005-07-27
"Stochastic Modeling of Coercivity " - A Measure of Non-equilibrium State
A typical coercivity versus particle size curve for magnetic nanoparticles has been explained by using the Gilbert equation followed by the corresponding Fokker Plank equation. Kramer's treatment has been employed to explain the increase in coercivity in the single domain region. The single to multi-domain transformati...
0507640v1
2005-09-13
Synchronization of spin-transfer oscillators driven by stimulated microwave currents
We have simulated the non-linear dynamics of networks of spin-transfer oscillators. The oscillators are magnetically uncoupled but electrically connected in series. We use a modified Landau-Lifschitz- Gilbert equation to describe the motion of each oscillator in the presence of the oscillations of all the others. We sh...
0509326v2
2005-11-04
Synchronized Magnetization Oscillations in F/N/F Nanopillars
Current-induced magnetization dynamics in a trilayer structure composed of two ferromagnetic free layers and a nonmagnetic spacer is examined. Both free layers are treated as a monodomain magnetic body with an uniform agnetization. The dynamics of the two magnetizations is modeled by modified Landau-Lifshitz-Gilbert eq...
0511095v1
2006-01-27
Dynamics of thin-film spin-flip transistors with perpendicular source-drain magnetizations
A "spin-flip transistor" is a lateral spin valve consisting of ferromagnetic source drain contacts to a thin-film normal-metal island with an electrically floating ferromagnetic base contact on top. We analyze the \emph{dc}-current-driven magnetization dynamics of spin-flip transistors in which the source-drain contact...
0601630v1
2007-03-17
Large-amplitude coherent spin waves exited by spin-polarized current in nanoscale spin valves
We present spectral measurements of spin-wave excitations driven by direct spinpolarized current in the free layer of nanoscale Ir20Mn80/Ni80Fe20/Cu/Ni80Fe20 spin valves. The measurements reveal that large-amplitude coherent spin wave modes are excited over a wide range of bias current. The frequency of these excitatio...
0703458v2
2001-12-11
A Data Mining Framework for Optimal Product Selection in Retail Supermarket Data: The Generalized PROFSET Model
In recent years, data mining researchers have developed efficient association rule algorithms for retail market basket analysis. Still, retailers often complain about how to adopt association rules to optimize concrete retail marketing-mix decisions. It is in this context that, in a previous paper, the authors have int...
0112013v1
2005-02-22
The QuarkNet/Grid Collaborative Learning e-Lab
We describe a case study that uses grid computing techniques to support the collaborative learning of high school students investigating cosmic rays. Students gather and upload science data to our e-Lab portal. They explore those data using techniques from the GriPhyN collaboration. These techniques include virtual dat...
0502089v1
2006-10-11
Properties of codes in rank metric
We study properties of rank metric and codes in rank metric over finite fields. We show that in rank metric perfect codes do not exist. We derive an existence bound that is the equivalent of the Gilbert--Varshamov bound in Hamming metric. We study the asymptotic behavior of the minimum rank distance of codes satisfying...
0610057v1