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2020-08-25
Stability results of coupled wave models with locally memory in a past history framework via non smooth coefficients on the interface
In this paper, we investigate the stabilization of a locally coupled wave equations with local viscoelastic damping of past history type acting only in one equation via non smooth coefficients. First, using a general criteria of Arendt-Batty, we prove the strong stability of our system. Second, using a frequency domain...
2008.11596v1
2021-04-24
Convex optimization via inertial algorithms with vanishing Tikhonov regularization: fast convergence to the minimum norm solution
In a Hilbertian framework, for the minimization of a general convex differentiable function $f$, we introduce new inertial dynamics and algorithms that generate trajectories and iterates that converge fastly towards the minimizer of $f$ with minimum norm. Our study is based on the non-autonomous version of the Polyak h...
2104.11987v1
2021-08-13
Topology optimization for acoustic structures considering viscous and thermal boundary layers using a sequential linearized Navier-Stokes model
This study proposes a level set-based topology optimization method for designing acoustic structures with viscous and thermal boundary layers in perspective. Acoustic waves propagating in a narrow channel are damped by viscous and thermal boundary layers. To estimate these viscothermal effects, we first introduce a seq...
2108.06116v2
2021-10-12
Computing semigroups with error control
We develop an algorithm that computes strongly continuous semigroups on infinite-dimensional Hilbert spaces with explicit error control. Given a generator $A$, a time $t>0$, an arbitrary initial vector $u_0$ and an error tolerance $\epsilon>0$, the algorithm computes $\exp(tA)u_0$ with error bounded by $\epsilon$. The ...
2110.06350v1
2021-10-16
Global well-posedness, stability and instability for the non-viscous Oldroyd-B model
In this paper we consider the 3-dimensional incompressible Oldroyd-B model. First, we establish two results of the global existence for different kinds of the coupling coefficient $k$. Then, we prove that the solutions $(u,\tau)$ are globally steady when $k^m\rightarrow k>0$, though $(u,\tau)$ corresponds to different ...
2110.08475v1
2021-11-01
Dissipative superfluid relativistic magnetohydrodynamics of a multicomponent fluid: the combined effect of particle diffusion and vortices
We formulate dissipative magnetohydrodynamic equations for finite-temperature superfluid and superconducting charged relativistic mixtures, taking into account the effects of particle diffusion and possible presence of Feynman-Onsager and/or Abrikosov vortices in the system. The equations depend on a number of phenomen...
2111.00999v1
2021-11-11
Quasinormal modes of charged black holes with corrections from nonlinear electrodynamics
We study quasinormal modes related to gravitational and electromagnetic perturbations of spherically symmetric charged black holes in nonlinear electrodynamics. Beyond the linear Maxwell electrodynamics, we consider a class of Lagrangian with higher-order corrections written by the electromagnetic field strength and it...
2111.06273v2
2022-06-29
Strongly coupled quantum Otto cycle with single qubit bath
We discuss a model of a closed quantum evolution of two-qubits where the joint Hamiltonian is so chosen that one of the qubits acts as a bath and thermalize the other qubit which is acting as the system. The corresponding exact master equation for the system is derived. Interestingly, for a specific choice of parameter...
2206.14751v1
2022-08-29
Benchmarking magnetized three-wave coupling for laser backscattering: Analytic solutions and kinetic simulations
Understanding magnetized laser-plasma interactions is important for controlling magneto-inertial fusion experiments and developing magnetically assisted radiation and particle sources. In the long-pulse regime, interactions are dominated by coherent three-wave interactions, whose nonlinear coupling coefficients become ...
2208.13832v2
2022-09-07
Acoustic attenuation in magnetic insulator films: effects of magnon polaron formation
A magnon and a phonon are the quanta of spin wave and lattice wave, respectively, and they can hybridize into a magnon polaron when their frequencies and wavenumbers match close enough the values at the exceptional point. Guided by an analytically calculated magnon polaron dispersion, dynamical phase-field simulations ...
2209.03481v2
2023-02-27
Diagonal State Space Augmented Transformers for Speech Recognition
We improve on the popular conformer architecture by replacing the depthwise temporal convolutions with diagonal state space (DSS) models. DSS is a recently introduced variant of linear RNNs obtained by discretizing a linear dynamical system with a diagonal state transition matrix. DSS layers project the input sequence ...
2302.14120v1
2023-03-22
Invariants for time-dependent Hamiltonian systems
An exact invariant is derived for $n$-degree-of-freedom Hamiltonian systems with general time-dependent potentials. The invariant is worked out in two equivalent ways. In the first approach, we define a special {\it Ansatz\/} for the invariant and determine its time-dependent coefficients. In the second approach, we pe...
2303.12746v1
2023-04-25
Room dimensions and absorption inference from room transfer function via machine learning
The inference of the absorption configuration of an existing room solely using acoustic signals can be challenging. This research presents two methods for estimating the room dimensions and frequency-dependent absorption coefficients using room transfer functions. The first method, a knowledge-based approach, calculate...
2304.12993v1
2023-06-19
Reciprocal hydrodynamic response estimation in a random spreading sea
Direct estimation of the hydrodynamic response of an offshore structure in a random spreading sea can lead to large computational costs. In this paper the actual spreading sea is replaced by an idealised diffuse wave field and the diffuse field reciprocity (DFR) relationship is derived analytically and verified against...
2306.11058v1
2023-09-11
Design of a Freely Rotating Wind Tunnel Test Bench for Measurements of Dynamic Coefficients
The needs to improve performances of artillery projectiles require accurate aerodynamic investigation methods. The aerodynamic design of a projectile usually starts from numerical analyses, mostly including semiempirical methods and/or Computational Fluid Dynamics (CFD), up to experimental techniques composed of wind-t...
2309.05302v1
2006-02-20
Fluctuation theorem applied to the Nosé-Hoover thermostated Lorentz gas
We present numerical evidence supporting the validity of the Gallavotti-Cohen Fluctuation Theorem applied to the driven Lorentz gas with Nos\'e-Hoover thermostating. It is moreover argued that the asymptotic form of the fluctuation formula is independent of the amplitude of the driving force, in the limit where it is s...
0602458v1
1997-12-28
Model-independent $\tan β$ bounds in the MSSM
We demonstrate, through the study of the one-loop effective potential in the MSSM, the existence of fully model-independent lower and upper theoretical bounds on $\tan \beta$. We give their general analytic form and illustrate some of their implications.
9712529v1
2006-12-26
Very Light Gravitino Dark Matter
We address the question of dark matter in the context of gauge mediated supersymmetry breaking models. In contrast with mSUGRA scenarios, the messenger of the susy breaking to the visible sector can play an important role allowing a relic gravitino in the $\sim {keV}$ to $10 {MeV}$ mass range to account for the cold da...
0612331v1
2004-09-15
Characterizing rigid simplicial actions on trees
We extend Forester's rigidity theorem so as to give a complete characterization of rigid group actions on trees (an action is rigid if it is the only reduced action in its deformation space, in particular it is invariant under automorphisms preserving the set of elliptic subgroups).
0409245v1
2005-12-14
Efficient Construction of Photonic Quantum Computational Clusters
We demonstrate a method of creating photonic two-dimensional cluster states that is considerably more efficient than previously proposed approaches. Our method uses only local unitaries and type-I fusion operations. The increased efficiency of our method compared to previously proposed constructions is obtained by iden...
0512110v1
2007-10-26
The dark matter as a light gravitino
We address the question of gravitino dark matter in the context of gauge mediated supersymmetry breaking models. A special emphasis is put on the role played by the MSSM singlet messenger in the case of SO(10) grand unification.
0710.5121v1
2008-03-05
Innovative Weak Formulation for The Landau-Lifshitz-Gilbert Equations
A non-conventional finite element formalism is proposed to solve the dynamic Landau-Lifshitz-Gilbert micromagnetic equations. Two bidimensional test problems are treated to estimate the validity and the accuracy of this finite element approach
0803.0599v1
2008-10-27
The profile of bubbling solutions of a class of fourth order geometric equations on 4-manifolds
We study a class of fourth order geometric equations defined on a 4-dimensional compact Riemannian manifold which includes the Q-curvature equation. We obtain sharp estimates on the difference near the blow-up points between a bubbling sequence of solutions and the standard bubble.
0810.4879v1
2009-03-02
Asymptotic Improvement of the Binary Gilbert-Varshamov Bound on the Code Rate
We compute the code parameters for binary linear codes obtained by greedy constructing the parity check matrix. Then we show that these codes improve the Gilbert-Varshamov (GV) bound on the code size and rate. This result counter proves the conjecture on the asymptotical exactness of the binary GV bound.
0903.0302v2
2009-11-16
The Independent Chip Model and Risk Aversion
We consider the Independent Chip Model (ICM) for expected value in poker tournaments. Our first result is that participating in a fair bet with one other player will always lower one's expected value under this model. Our second result is that the expected value for players not participating in a fair bet between two p...
0911.3100v1
2011-03-29
Statistical properties of $r$-adic processes and their connections to families of popular fractal curves
Results concerning the statists of $r$-adic processes and their fractal properties are reviewed. The connection between singular eigenstates of the statistical evolution of such processes and popular fractal curves is emphasized.
1103.5683v1
2011-05-09
Global Solvability of the Cauchy Problem for the Landau-Lifshitz-Gilbert Equation in Higher Dimensions
We prove existence, uniqueness and asymptotics of global smooth solutions for the Landau-Lifshitz-Gilbert equation in dimension $n \ge 3$, valid under a smallness condition of initial gradients in the $L^n$ norm. The argument is based on the method of moving frames that produces a covariant complex Ginzburg-Landau equa...
1105.1597v1
2012-03-28
Fibonacci numbers in phyllotaxis : a simple model
A simple model is presented which explains the occurrence of high order Fibonacci number parastichies in asteracae flowers by two distinct steps. First low order parastichies result from the fact that a new floret, at its appearance is repelled by two former ones, then, in order to accommodate for the increase of the r...
1203.6257v1
2014-02-19
Ordered groupoids and the holomorph of an inverse semigroup
We present a construction for the holomorph of an inverse semigroup, derived from the cartesian closed structure of the category of ordered groupoids. We compare the holomorph with the monoid of mappings that preserve the ternary heap operation on an inverse semigroup: for groups these two constructions coincide. We pr...
1402.4592v1
2014-11-01
Functorial Zeta Integrals
The functional equation for nonarchimedean Rankin-Selberg local Euler factors was proved by Jacquet, Piatetski-Shapiro, and Shalika in 1983. In this expository note we translate the original proof into the purely functorial language of parabolic induction-restriction of Bernstein-Zelevinsky. This new language gives a c...
1411.0148v1
2016-02-17
Dispersion and Scaling Law of Dynamic Hysteresis Based on the Landau-Lifshitz-Gilbert Model
Hysteresis dispersion under a varying external field Hex is investigated through numerical simulations based on the Landau-Lifshitz-Gilbert (LLG) equation, indicating the energy dissipation can be determined by W({\eta}) = A (f, H0). A linear relation between area of hysteresis and magnitude of external field is discov...
1602.05375v1
2016-06-06
Proof of tightness of Varshamov - Gilbert bound for binary codes
We prove tightness of right logarithmic asymptotic of Varshamov- Gilbert bound for linear binary codes We find general asymptotic coding bound for linear codes
1606.01592v5
2017-02-21
Cohomology and extensions of ordered groupoids
We adapt and generalise results of Loganathan on the cohomology of inverse semigroups to the cohomology of ordered groupoids. We then derive a five-term exact sequence in cohomology from an extension of ordered groupoids, and show that this sequence leads to a classification of extensions by a second cohomology group. ...
1702.06333v1
2017-05-11
Two Gilbert-Varshamov Type Existential Bounds for Asymmetric Quantum Error-Correcting Codes
In this note we report two versions of Gilbert-Varshamov type existential bounds for asymmetric quantum error-correcting codes.
1705.04087v2
2017-09-21
Self-Dual Codes better than the Gilbert--Varshamov bound
We show that every self-orthogonal code over $\mathbb F_q$ of length $n$ can be extended to a self-dual code, if there exists self-dual codes of length $n$. Using a family of Galois towers of algebraic function fields we show that over any nonprime field $\mathbb F_q$, with $q\geq 64$, except possibly $q=125$, there ar...
1709.07221v1
2018-10-12
A convex approach to the Gilbert-Steiner problem
We describe a convex relaxation for the Gilbert-Steiner problem both in $R^d$ and on manifolds, extending the framework proposed in [9], and we discuss its sharpness by means of calibration type arguments. The minimization of the resulting problem is then tackled numerically and we present results for an extensive set ...
1810.05417v1
2018-11-09
Finslerian metrics locally conformally $R$-Einstein
Let $R$ be the $hh$-curvature associated with the Chern connection or the Cartan connection. Adopting the pulled-back tangent bundle approach to the Finslerian Geometry, an intrinsic characterization of $R$-Einstein metrics is given. Finslerian metrics which are locally conformally $R$-Einstein are classified.
1811.04077v3
2019-02-05
Harmonic maps with prescribed singularities and applications in general relativity
This paper presents a general existence and uniqueness result for harmonic maps with prescribed singularities into non-positively curved targets, and surveys a number of applications to general relativity. It is based on a talk delivered by the author at The 11th Mathematical Society of Japan Seasonal Institute, The Ro...
1902.01576v2
2020-03-13
3D Stochastic Landau-Lifshitz-Gilbert Equations coupled with Maxwell's Equations with full energy
We consider 3D stochastic Landau-Lifshitz-Gilbert equations coupled with the Maxwell equations with the full energy. We have proved the existence and some further regularities of the weak solution.
2003.06091v4
2021-12-09
Induced Semi-Riemannian structures on null submanifolds
In this paper, we induce a semi-Riemannian metric on the $r$-null submanifold. We establish the links between the null geometry and basics invariants of the associated semi-Riemannian geometry on $r$-null submanifold and semi-Riemannian constructed from a semi-Riemannian ambient.
2112.07348v1
2022-04-12
How to design a network architecture using capacity planning
Building a network architecture must answer to organization needs, but also to two major elements which are the need for dependability and performance. By performance, we must understand the ability to meet an immediate need and the ability to scale without reducing the performance of the whole as new elements are adde...
2204.05916v2
2022-07-31
Moduli of Representations of Skewed-Gentle Algebras
We prove irreducible components of moduli spaces of semistable representations of skewed-gentle algebras, and more generally, clannish algebras, are isomorphic to products of projective spaces. This is achieved by showing irreducible components of varieties of representations of clannish algebras can be viewed as irred...
2208.00336v1
2022-08-01
iOCR: Informed Optical Character Recognition for Election Ballot Tallies
The purpose of this study is to explore the performance of Informed OCR or iOCR. iOCR was developed with a spell correction algorithm to fix errors introduced by conventional OCR for vote tabulation. The results found that the iOCR system outperforms conventional OCR techniques.
2208.00865v1
2023-03-13
Adaptive mesh refinement for the Landau-Lifshitz-Gilbert equation
We propose a new adaptive algorithm for the approximation of the Landau-Lifshitz-Gilbert equation via a higher-order tangent plane scheme. We show that the adaptive approximation satisfies an energy inequality and demonstrate numerically, that the adaptive algorithm outperforms uniform approaches.
2303.07463v1
2023-05-08
Evaluation of the Gilbert-Varshamov Bound using Multivariate Analytic Combinatorics
Analytic combinatorics in several variables refers to a suite of tools that provide sharp asymptotic estimates for certain combinatorial quantities. In this paper, we apply these tools to determine the Gilbert-Varshamov (GV) bound for the sticky insertion and the constrained-synthesis channel.
2305.04439v1
2023-12-11
Matrix Formulae and Skein Relations for Quasi-cluster Algebras
In this paper, we give matrix formulae for non-orientable surfaces that provide the Laurent expansion for quasi-cluster variables, generalizing the orientable surface matrix formulae by Musiker-Williams. We additionally use our matrix formulas to prove the skein relations for the elements in the quasi-cluster algebra a...
2312.06148v1
2009-08-12
Linear Fractionally Damped Oscillator
In this paper the linearly damped oscillator equation is considered with the damping term generalized to a Caputo fractional derivative. The order of the derivative being considered is 0 less than or equal to nu which is less than or equal to 1 . At the lower end, nu = 0, the equation represents an un-damped oscillator...
0908.1683v1
1997-10-02
Dust and elemental abundances in Damped Ly alpha absorbers
The effects of the dust on the determination of elemental abundances in damped Ly alpha (DLA) absorbers are investigated. Relations between the observed abundances measured in the gas phase and the overall abundances (gas plus dust) are derived as a function of dust-to-gas ratio, metallicity, element-to-element abundan...
9710026v1
2002-11-26
R-modes of neutron stars with the superfluid core
We investigate the modal properties of the $r$-modes of rotating neutron stars with the core filled with neutron and proton superfluids, taking account of entrainment effects between the superfluids. The stability of the $r$-modes against gravitational radiation reaction is also examined considering viscous dissipation...
0211580v1
2006-02-06
Voigt Profile Fitting to Quasar Absorption Lines: An Analytic Approximation to the Voigt-Hjerting Function
The Voigt-Hjerting function is fundamental in order to correctly model the profiles of absorption lines imprinted in the spectra of bright background sources by intervening absorbing systems. In this work we present a simple analytic approximation to this function in the context of absorption line profiles of intergala...
0602124v2
2003-10-29
Superparamagnetism and Spin Glass Dynamics of Interacting Magnetic Nanoparticle Systems
The physical properties of magnetic nanoparticles have been investigated with focus on the influence of dipolar interparticle interaction. For weakly coupled nanoparticles, thermodynamic perturbation theory is employed to derive analytical expressions for the linear equilibrium susceptibility, the zero-field specific h...
0310684v2
1996-12-31
Fluid Models for Kinetic Effects on Coherent Nonlinear Alfven Waves. I. Fundamental Theory
Collisionless regime kinetic models for coherent nonlinear Alfven wave dynamics are studied using fluid moment equations with an approximate closure anzatz. Resonant particle effects are modelled by incorporating an additional term representing dissipation akin to parallel heat conduction. Unlike collisional dissipatio...
9612017v1
2008-06-01
Ray-based calculations of backscatter in laser fusion targets
A 1D, steady-state model for Brillouin and Raman backscatter from an inhomogeneous plasma is presented. The daughter plasma waves are treated in the strong damping limit, and have amplitudes given by the (linear) kinetic response to the ponderomotive drive. Pump depletion, inverse-bremsstrahlung damping, bremsstrahlung...
0806.0045v2
2015-07-06
Fast inertial dynamics and FISTA algorithms in convex optimization. Perturbation aspects
In a Hilbert space setting $\mathcal H$, we study the fast convergence properties as $t \to + \infty$ of the trajectories of the second-order differential equation $ \ddot{x}(t) + \frac{\alpha}{t} \dot{x}(t) + \nabla \Phi (x(t)) = g(t)$, where $\nabla\Phi$ is the gradient of a convex continuously differentiable functio...
1507.01367v1
2016-02-05
Combining fast inertial dynamics for convex optimization with Tikhonov regularization
In a Hilbert space setting $\mathcal H$, we study the convergence properties as $t \to + \infty$ of the trajectories of the second-order differential equation \begin{equation*} \mbox{(AVD)}_{\alpha, \epsilon} \quad \quad \ddot{x}(t) + \frac{\alpha}{t} \dot{x}(t) + \nabla \Phi (x(t)) + \epsilon (t) x(t) =0, \end{equat...
1602.01973v1
2016-02-19
Resonant absorption and amplification of circularly-polarized waves in inhomogeneous chiral media
It has been found that in the media where the dielectric permittivity $\epsilon$ or the magnetic permeability $\mu$ is near zero and in transition metamaterials where $\epsilon$ or $\mu$ changes from positive to negative values, there occur a strong absorption or amplification of the electromagnetic wave energy in the ...
1602.06022v1
2018-06-22
Overcoming obstacles in nonequilibrium holography
We study universal spatial features of certain non-equilibrium steady states corresponding to flows of strongly correlated fluids over obstacles. This allows us to predict universal spatial features of far-from-equilibrium systems, which in certain interesting cases depend cleanly on the hydrodynamic transport coeffici...
1806.08655v1
2018-06-28
Optimizing wave-generation and wave-damping in 3D-flow simulations with implicit relaxation-zones
In finite-volume-based flow-simulations with free-surface waves, wave reflections at the domain boundaries can cause substantial errors in the results and must therefore be minimized. This can be achieved via `implicit relaxation zones', but only if the relaxation zone's case-dependent parameters are optimized. This wo...
1806.10995v3
2018-07-06
On the use of circulant matrices for the stability analysis of recent weakly compressible SPH methods
In this study, a linear stability analysis is performed for different Weakly Compressible Smooth Particle Hydrodynamics (WCSPH) methods on a 1D periodic domain describing an incompressible base flow. The perturbation equation can be vectorized and written as an ordinary differential equation where the coefficients are ...
1807.02315v2
2018-08-15
Pull-in dynamics of overdamped microbeams
We study the dynamics of MEMS microbeams undergoing electrostatic pull-in. At DC voltages close to the pull-in voltage, experiments and numerical simulations have reported `bottleneck' behaviour in which the transient dynamics slow down considerably. This slowing down is highly sensitive to external forces, and so has ...
1808.05237v1
2019-07-05
Response solutions to quasi-periodically forced systems, even to possibly ill-posed PDEs, with strong dissipation and any frequency vectors
We consider several models (including both multidimensional ordinary differential equations (ODEs) and partial differential equations (PDEs), possibly ill-posed), subject to very strong damping and quasi-periodic external forcing. We study the existence of response solutions (i.e., quasi-periodic solutions with the sam...
1907.02835v1
2020-06-23
Unexpected convergence of lattice Boltzmann schemes
In this work, we study numerically the convergence of the scalar D2Q9 lattice Boltzmann scheme with multiple relaxation times when the time step is proportional to the space step and tends to zero. We do this by a combination of theory and numerical experiment. The classical formal analysis when all the relaxation para...
2006.12947v1
2020-09-13
Inertia and feedback parameters adaptive control of virtual synchronous generator
The virtual synchronous generator technology analogs the characteristics of the synchronous generator via the controller design. It improved the stability of the grid systems which include the new energy. At the same time, according to the adjustable characteristics of the virtual synchronous generator parameters, the ...
2009.05916v1
2021-02-03
Jerky active matter: a phase field crystal model with translational and orientational memory
Most field theories for active matter neglect effects of memory and inertia. However, recent experiments have found inertial delay to be important for the motion of self-propelled particles. A major challenge in the theoretical description of these effects, which makes the application of standard methods very difficult...
2102.02169v1
2021-04-23
Development of Advanced Linearized Gyrokinetic Collision Operators Using a Moment Approach
The derivation and numerical implementation of a linearized version of the gyrokinetic (GK) Coulomb collision operator (Jorge R. et al., J. Plasma Phys. 85, 905850604 (2019)) and of the widely-used linearized GK Sugama collision operator (Sugama H. et al., Phys. Plasmas 16, 112503 (2009)) is reported. An approach based...
2104.11480v2
2021-05-19
Viscoelasticity and elastocapillarity effects in the impact of drops on a repellent surface
We investigate freely expanding viscoelastic sheets. The sheets are produced by the impact of drops on a quartz plate covered with a thin layer of liquid nitrogen that suppresses shear viscous dissipation as a result of the cold Leidenfrost effect. The time evolution of the sheet is simultaneously recorded from top and...
2105.09244v1
2021-12-29
Towards First-principle Characterization of Cosmic-ray Transport Coefficients from Multi-scale Kinetic Simulations
A major uncertainty in understanding the transport and feedback of cosmic-rays (CRs) within and beyond our Galaxy lies in the unknown CR scattering rates, which are primarily determined by wave-particle interaction at microscopic gyro-resonant scales. The source of the waves for the bulk CR population is believed to be...
2112.14782v2
2022-01-17
Sizing of Energy Storage System for Virtual Inertia Emulation
The infusion of renewable energy sources into the conventional synchronous generation system decreases the overall system inertia and negatively impacts the stability of its primary frequency response. The lowered inertia is due to the absence of inertia in some of the renewable energy-based systems. To maintain the st...
2201.06566v2
2022-04-12
The drag exerted by weakly dissipative trapped lee waves on the atmosphere: application to Scorer's two-layer model
While it is known that trapped lee waves propagating at low levels in a stratified atmosphere exert a drag on the mountains that generate them, the distribution of the corresponding reaction force exerted on the atmospheric mean circulation, defined by the wave momentum flux profiles, has not been established, because ...
2204.05858v1
2022-08-30
Hyperon bulk viscosity and $r$-modes of neutron stars
We propose and apply a new parameterization of the modified chiral effective model to study rotating neutron stars with hyperon cores in the framework of the relativistic mean-field theory. The inclusion of mesonic cross couplings in the model has improved the density content of the symmetry energy slope parameters, wh...
2208.14436v1
2023-02-19
Non-separable Covariance Kernels for Spatiotemporal Gaussian Processes based on a Hybrid Spectral Method and the Harmonic Oscillator
Gaussian processes provide a flexible, non-parametric framework for the approximation of functions in high-dimensional spaces. The covariance kernel is the main engine of Gaussian processes, incorporating correlations that underpin the predictive distribution. For applications with spatiotemporal datasets, suitable ker...
2302.09580v3
2023-11-28
Energy diffusion in weakly interacting chains with fermionic dissipation-assisted operator evolution
Interacting lattice Hamiltonians at high temperature generically give rise to energy transport governed by the classical diffusion equation; however, predicting the rate of diffusion requires numerical simulation of the microscopic quantum dynamics. For the purpose of predicting such transport properties, computational...
2311.17148v2
2005-03-08
Electron-Ion Recombination Rate Coefficients and Photoionization Cross Sections for Astrophysically Abundant Elements. IX. Ni XXVI and Ni XXVII for UV and X-ray modeling
The inverse processes of photoionization and electron-ion recombination of (hnu + Ni XXVI --> Ni XXVII + e and (hnu + Ni XXVII --> Ni XXVIII + e) are studied using the unified method for the total recombination. The method subsumes both the radiative and di-electronic recombination processes and enables self-consistent...
0503197v1
2013-09-12
Diffusive transport in Weyl semimetals
Diffusion, a ubiquitous phenomenon in nature, is a consequence of particle number conservation and locality, in systems with sufficient damping. In this paper we consider diffusive processes in the bulk of Weyl semimetals, which are exotic quantum materials, recently of considerable interest. In order to do this, we fi...
1309.3278v1
2018-01-03
Gravitational Waves in Locally Rotationally Symmetric (LRS) Class II Cosmologies
In this work we consider perturbations of homogeneous and hypersurface orthogonal cosmological backgrounds with local rotational symmetry (LRS), using a method based on the 1 + 1 + 2 covariant split of spacetime. The backgrounds, of LRS class II, are characterised by that the vorticity, the twist of the 2-sheets, and t...
1801.01147v1
2019-04-12
Phonon hydrodynamics, thermal conductivity and second sound in 2D crystals
Starting from our previous work where we have obtained a system of coupled integro-differential equations for acoustic sound waves and phonon density fluctuations in 2D crystals, we derive here the corresponding hydrodynamic equations and study their consequences as function of temperature and frequency. These phenomen...
1904.06327v1
2020-12-17
Surface wave scattering by multiple flexible fishing cage system
A study of the wave dynamics around a multiple fishing cage system is carried out under the assumption of the linear water wave theory and small-amplitude wave response. The Fourier--Bessel series expansion of the velocity potential is derived for regions enclosed under the open-water and cage systems and in the immedi...
2012.09522v1
2021-01-19
Role of nucleon-nucleon correlation in transport coefficients and gravitational-wave-driven $r$-mode instability of neutron stars
The thermal conductivity and shear viscosity of dense nuclear matter, along with the corresponding shear viscosity timescale of canonical neutron stars (NSs), are investigated, where the effect of Fermi surface depletion (i.e., the $Z$-factor effect) induced by the nucleon-nucleon correlation are taken into account. Th...
2101.07551v1
2022-07-12
Operator growth and Krylov construction in dissipative open quantum systems
Inspired by the universal operator growth hypothesis, we extend the formalism of Krylov construction in dissipative open quantum systems connected to a Markovian bath. Our construction is based upon the modification of the Liouvillian superoperator by the appropriate Lindbladian, thereby following the vectorized Lanczo...
2207.05347v3
2022-09-27
Inertio-capillary rebound of a droplet impacting a fluid bath
The rebound of droplets impacting a deep fluid bath is studied both experimentally and theoretically. Millimetric drops are generated using a piezoelectric droplet-on-demand generator and normally impact a bath of the same fluid. Measurements of the droplet trajectory and other rebound metrics are compared directly to ...
2209.13276v2
2017-06-28
Generating Log-normal Mock Catalog of Galaxies in Redshift Space
We present a public code to generate a mock galaxy catalog in redshift space assuming a log-normal probability density function (PDF) of galaxy and matter density fields. We draw galaxies by Poisson-sampling the log-normal field, and calculate the velocity field from the linearised continuity equation of matter fields,...
1706.09195v2
2021-02-22
Slow-Mode Magnetoacoustic Waves in Coronal Loops
Rapidly decaying long-period oscillations often occur in hot coronal loops of active regions associated with small (or micro-) flares. This kind of wave activity was first discovered with the SOHO/SUMER spectrometer from Doppler velocity measurements of hot emission lines, thus also often called "SUMER" oscillations. T...
2102.11376v1
2022-05-29
Modeling the Dynamics of the Coronavirus SARS-CoV-2 Pandemic using Modified SIR Model with the 'Damped-Oscillator' Dynamics of the Effective Reproduction Number
The COVID-19 pandemic has been a great catastrophe that upended human lives and caused millions of deaths all over the world. The rapid spread of the virus, with its early-stage exponential growth and subsequent 'waves', caught many medical professionals and decision-makers unprepared. Even though epidemiological model...
2205.14747v1
2023-08-03
Part I: Rebuttal to "Uniform stabilization for the Timoshenko beam by a locally distributed damping"
A paper, entitled "Uniform stabilization for the Timoshenko beam by a locally distributed damping" was published in 2003, in the journal Electronic Journal of Differential Equations. Its title concerns exclusively its Section 3, devoted to the case of equal speeds of propagation and to its main theorem, namely Theorem ...
2308.01611v1
2023-08-05
Modulating Spin Current Induced Effective Damping in $β-W/Py$ Heterostructures by a Systematic Variation in Resistivity of the Sputtered Deposited $β-W$ films
Utilizing the spin-induced pumping from a ferromagnet (FM) into a heavy metal (HM) under the ferromagnetic resonance (FMR) condition, we report an enhancement in effective damping in $\beta$- W/Py bilayers by systematically varying resistivity ($\rho_{W}$) of $\beta$-W films. Different resistivity ranging from 100 $\mu...
2308.02939v1
2004-05-06
On a theorem of Kac and Gilbert
We prove a general operator theoretic result that asserts that many multiplicity two selfadjoint operators have simple singular spectrum.
0405110v1
2011-01-05
Beating the Gilbert-Varshamov Bound for Online Channels
In the online channel coding model, a sender wishes to communicate a message to a receiver by transmitting a codeword x =(x_1,...,x_n) in {0,1}^n bit by bit via a channel limited to at most pn corruptions. The channel is online in the sense that at the ith step the channel decides whether to flip the ith bit or not and...
1101.1045v1
2014-11-25
From heavy-tailed Boolean models to scale-free Gilbert graphs
Define the scale-free Gilbert graph based on a Boolean model with heavy-tailed radius distribution on the $d$-dimensional torus by connecting two centers of balls by an edge if at least one of the balls contains the center of the other. We investigate two asymptotic properties of this graph as the size of the torus ten...
1411.6824v1
2016-03-16
Recent Results from SPLASH: Chemical Abundances and Kinematics of Andromeda's Stellar Halo
Large scale surveys of Andromeda's resolved stellar populations have revolutionized our view of this galaxy over the past decade. The combination of large-scale, contiguous photometric surveys and pointed spectroscopic surveys has been particularly powerful for discovering substructure and disentangling the structural ...
1603.05160v1
2017-05-09
Gilbert's disc model with geostatistical marking
We study a variant of Gilbert's disc model, in which discs are positioned at the points of a Poisson process in $\mathbb{R}^2$ with radii determined by an underlying stationary and ergodic random field $\varphi:\mathbb{R}^2\to[0,\infty)$, independent of the Poisson process. When the random field is independent of the p...
1705.03337v2
2019-01-30
Is the mailing Gilbert-Steiner problem convex?
A convexification of the mailing version of the finite Gilbert problem for optimal networks is introduced. It is ia convex functional on the set of probability measures subject to the Wasserstein $p-$ metric. The minimizer of this convex functional is a measure supported in a graph. If this graph is a tree (i.e contain...
1901.10924v4
2019-11-06
Phase transitions for chase-escape models on Gilbert graphs
We present results on phase transitions of local and global survival in a two-species model on Gilbert graphs. At initial time there is an infection at the origin that propagates on the Gilbert graph according to a continuous-time nearest-neighbor interacting particle system. The Gilbert graph consists of susceptible n...
1911.02622v2
2019-12-13
Distance between Bound Entangled States from Unextendible Product Bases and Separable States
We discuss the use of the Gilbert algorithm to tailor entanglement witnesses for unextendibleproduct basis bound entangled states (UPB BE states). The method relies on the fact that an optimalentanglement witness is given by a plane perpendicular to a line between the reference state, entanglementof which is to be witn...
1912.06569v2
2020-10-16
Genome organization: experiments and modelling
This is an introduction to the special issue Genome organization: experiments and simulations, published in Chromosome Research, volume 25, issue 1 (2017).
2010.08464v1
2023-10-17
Sparse grid approximation of stochastic parabolic PDEs: The Landau--Lifshitz--Gilbert equation
We show convergence rates for a sparse grid approximation of the distribution of solutions of the stochastic Landau-Lifshitz-Gilbert equation. Beyond being a frequently studied equation in engineering and physics, the stochastic Landau-Lifshitz-Gilbert equation poses many interesting challenges that do not appear simul...
2310.11225v2
2024-04-04
Resolving Gilbert's Conjecture: Dimensional Dependencies in Hardy Spaces Valued in Clifford Modules
This article provides a thorough investigation into Gilbert's Conjecture, pertaining to Hardy spaces in the upper half-space valued in Clifford modules. We explore the conjecture proposed by Gilbert in 1991, which seeks to extend the classical principle of representing real $L^p$ functions on the real line as boundary ...
2404.03478v1
1998-02-23
Shell Effects on Rotational Damping in Superdeformed Nuclei
Damping of rotational motion in superdeformed Hg and Dy-region nuclei is studied by means of cranked shell model diagonalization. It is shown that a shell oscillation in single-particle alignments affects significantly properties of rotational damping. Onset properties of damping and damping width for Hg are quite diff...
9802065v1
2003-08-29
Influence of radiative damping on the optical-frequency susceptibility
Motivated by recent discussions concerning the manner in which damping appears in the electric polarizability, we show that (a) there is a dependence of the nonresonant contribution on the damping and that (b) the damping enters according to the "opposite sign prescription." We also discuss the related question of how ...
0309001v1
2024-03-19
Weakly elliptic damping gives sharp decay
We prove that weakly elliptic damping gives sharp energy decay for the abstract damped wave semigroup, where the damping is not in the functional calculus. In this case, there is no overdamping. We show applications in linearised water waves and Kelvin--Voigt damping.
2403.13067v1
2019-02-25
Resonant absorption as a damping mechanism for the transverse oscillations of the coronal loops observed by SDO/AIA
Solar coronal loops represent the variety of fast, intermediate, and slow normal mode oscillations. In this study, the transverse oscillations of the loops with a few-minutes period and also with damping caused by the resonant absorption were analyzed using extreme ultraviolet (EUV) images of the Sun. We employed the 1...
1902.09649v1