Search results for " second order"

showing 6 items of 6 documents

Existence and multiplicity of periodic solutions for second order Hamiltonian systems depending on a parameter

2013

The existence of at least one nontrivial periodic solution for a class of second order Hamiltonian systems depending on a parameter is obtained, under an algebraic condition on the nonlinearity G and without requiring any asymptotic behavior neither at zero nor at infinity. The existence is still deduced in the particular case when G is subquadratic at zero. Finally, two multiplicity results are proved if G, in addition, is required to fulfill some different Ambrosetti-Rabinowitz type superquadratic conditions at infinity. The approach is fully variational. © Heldermann Verlag.

Critical points Periodic solutions Second order hamiltonian systemsPeriodic solutionsPeriodic solutionCritical pointsSecond order hamiltonian systemsCritical point
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Global Non-monotonicity of Solutions to Nonlinear Second-Order Differential Equations

2018

We study behavior of solutions to two classes of nonlinear second-order differential equations with a damping term. Sufficient conditions for the first derivative of a solution x(t) to change sign at least once in a given interval (in a given infinite sequence of intervals) are provided. These conditions imply global non-monotone behavior of solutions.

Differential equationGeneral Mathematics010102 general mathematicsMonotonic functionInterval (mathematics)01 natural sciencesNonlinear differential equationsTerm (time)010101 applied mathematicsSecond order differential equationsNonlinear systemApplied mathematics0101 mathematicsNonlinear differential equations ; non-monotone behaviour ; second order ; damping term ; reciprocal equationSign (mathematics)MathematicsMediterranean Journal of Mathematics
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Blind Source Separation Based on Joint Diagonalization in R: The Packages JADE and BSSasymp

2017

Blind source separation (BSS) is a well-known signal processing tool which is used to solve practical data analysis problems in various fields of science. In BSS, we assume that the observed data consists of linear mixtures of latent variables. The mixing system and the distributions of the latent variables are unknown. The aim is to find an estimate of an unmixing matrix which then transforms the observed data back to latent sources. In this paper we present the R packages JADE and BSSasymp. The package JADE offers several BSS methods which are based on joint diagonalization. Package BSSasymp contains functions for computing the asymptotic covariance matrices as well as their data-based es…

Statistics and ProbabilityComputer scienceJADE (programming language)02 engineering and technologyLatent variableMachine learningcomputer.software_genre01 natural sciencesBlind signal separation010104 statistics & probabilityMatrix (mathematics)nonstationary source separationMixing (mathematics)0202 electrical engineering electronic engineering information engineeringsecond order source separation0101 mathematicslcsh:Statisticslcsh:HA1-4737computer.programming_languageta113Signal processingta112matematiikkamultivariate time seriesmathematicsbusiness.industryEstimator020206 networking & telecommunicationsriippumattomien komponenttien analyysiindependent component analysis; multivariate time series; nonstationary source separation; performance indices; second order source separationIndependent component analysisperformance indicesstatisticsindependent component analysisArtificial intelligenceStatistics Probability and UncertaintybusinesscomputerAlgorithmSoftwareJournal of Statistical Software
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Multiplicity results for systems of asymptotically linear second order equations

2002

Abstract We prove the existence and multiplicity of solutions, with prescribed nodal properties, for a BVP associated with a system of asymptotically linear second order equations. The applicability of an abstract continuation theorem is ensured by upper and lower bounds on the number of zeros of each component of a solution.

Asymptotically linearAsymptotically linear second order system continuation theoremGeneral MathematicsMultiplicity resultsMathematical analysisSecond order equationStatistical and Nonlinear PhysicsMathematicsAdvanced Nonlinear Studies
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Multiplicity of solutions of Dirichlet problems associated with second-order equations in ℝ2

2009

AbstractWe study the existence of multiple solutions for a two-point boundary-value problem associated with a planar system of second-order ordinary differential equations by using a shooting technique. We consider asymptotically linear nonlinearities satisfying suitable sign conditions. Multiplicity is ensured by assumptions involving the Morse indices of the linearizations at zero and at infinity.

General MathematicsDirichlet L-functionasymptotically linear multiplicity second order planar systems Morse indexDirichlet's energyDirichlet integralsymbols.namesakeDirichlet eigenvalueSettore MAT/05 - Analisi MatematicaDirichlet's principleOrdinary differential equationDirichlet boundary conditionsymbolsApplied mathematicsGeneral Dirichlet seriesMathematics
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Spatio-temporal log-Gaussian Cox processes on eartquake events

2017

In this paper we aim at studying some extensions of complex space-time models, useful for the description of earthquake data. In particular we want to focus on the Log-Gaussian Cox Process (LGCP) model estimation approach, with some results on global informal diagnostics. Indeed, in our opinion the use of Cox processes that are natural models for point process phenomena that are environmentally driven could be a new approach for the description of seismic events. These models can be useful in estimating the intensity surface of a spatio-temporal point process, in constructing spatially continuous maps of earthquake risk from spatially discrete data, and in real-time seismic activity surveil…

LGCP earthquake events second orderSettore SECS-S/01 - Statistica
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