The asymptotic behaviours for small and large amplitudes, A, of the period for a nonlinear oscillator, where the square of the angular frequency depends quadratically on the velocity, are obtained. These asymptotic expressions are compared with the exact period, T(A),…

In this paper, a novel model for monolingual Information Retrieval in English and Spanish language is proposed. This model uses Natural Language Processing techniques (a POS-tagger, a Partial Parser, and an Anaphora Resolver) in order to improve the precision of…

Two Lidstedt-Poincaré perturbation based methods are used to solve the nonlinear differential equation of a nonlinear oscillator having the square of the angular frequency depends quadratically on the velocity. Mickens published two interesting papers [1, 2] about this oscillator and…

The first-order harmonic balance method via the first Fourier coefficient is used to construct two approximate frequency–amplitude relations for a conservative nonlinear oscillatory system in which the restoring force has an irrational form. This system corresponds to the motion of…

Convergence properties are presented for Newton additive and multiplicative Schwarz (AS and MS) iterative methods for the solution of nonlinear systems in several variables. These methods consist of approximate solutions of the linear Newton step using either AS or MS…

We present a systematic algorithm capable of searching for optimal colors for any lightness L* (between 0 and
100), any illuminant (D65, F2, F7, F11, etc.), and any light source reported by CIE. Color solids are graphed in
some color…

Las clasificaciones geomecánicas son muy empleadas en mecánica de rocas para la caracterización de macizos rocosos. Entre las existentes para taludes, el SMR es una de las más empleadas. En el presente artículo se proponen una serie de funciones continuas…

The main step in the production of carbon nanofilaments is the catalytic nucleation and lengthening of the filament. An undesired parallel step in
the production of carbon nanofilaments is their thickening by pyrolitic carbon vapor deposition consisting in an ordered…

The homotopy perturbation method is used to solve the nonlinear differential equation that governs the nonlinear oscillations of a simple pendulum, and an approximate expression for its period is obtained. Only one iteration leads to high accuracy of the solutions…

Enantiomerically enriched cyanohydrin O-phosphates, prepared
by enantioselective cyanophosphorylation of α,β-unsaturated
aldehydes, react regioselectively at the γ-position
with organocuprates derived from alkyl Grignard reagents
and CuCN to afford chiral γ-alkyl-substituted α,β-unsaturated
nitriles. The configuration of the new C–C double bond
is…