1,721,015 research outputs found
On the Periodic BVP for the Forced Duffing Equation
No full textSi studiano condizioni sufficienti per l'esistenza e la molteplicità
esatta di soluzioni di una equazione del tipo di Duffing -Ax + =e,
con
lineare, con nucleo le costanti e imagine le funzioni a integrale
nullo, con inverso destro compatto, e dove a > 0, e .
Come applicazione, si studia il problema ai limiti periodico per l'equazione
ordinaria del tipo di Duffing
che quando n = 2 è la usuale equazione del pendolo forzato.We study the equation of Duffing type-Ax + =e, where
is a linear map whose kernel consists of constant mappings, the range
is the set of maps with mean value zero, having a compact rigth inverse,
and where a > 0, e . Sufficient conditions for
the existence and for the exact multiplicity of the solutions are
given. As an application, we consider the periodic BVP for the n-th
order ODE of Duffing type which
is, when n = 2 , the usual forced pendulum equation
Frequenza alleliche AB0 e computer algebra
No full textIf tha frequencies of the standard blood groups A, B, AB, 0 are known in a human population, then under the assmptions of the Hardy-Weinberg equilibrium, a direct nonlinear least squares algorithm on a computer algebra system returns the estimates for the A, B, 0 alleles frequencies. This algorithm is more informative than the classical EM (Expectation-Maximization)
On a Result by Carvalho Concerning Sarkovskii's Order
No full textAbstractIt is well known that the celebrated S̆arkovskii's Theorem [4] (cf. also [1]) defines a total ordering ▷ on the set N∗ of positive integers (the S̆arkovskii's order) such that, if f is a continuous map of an interval J of the real line R into itself with a periodic orbit of period p, and p ▷ q, then f has a periodic orbit of period q. The S̆arkovskii's order has a minimum, namely the period 3. Recently, Carvalho [2] has observed that the orbits considered in S̆arkovskii's Theorem are of a special kind with respect to the natural order on R of their points. Thus, in [2], he extended the classical S̆arkovskii's order below the standard minimum joining a sequence of so-called “n-step orbits”: an n-step orbit of a continuous map f: J → J (where J is an interval not reduced to a single point of the real line) is a periodic orbit (x1, x2, …, xn) of f with period n ⩾ 1, consisting of n distinct points x1 < x2 < ··· < xn with xj + 1 = f(xj) for j = 1, …, n − 1, and x1 = f(xn)
Remarks on Hopf Bifurcation Formulae
No full textMostriamo come la complessità delle formule di Hassard, Kazarinoff e Wan (1981) riguardanti la biforcazione di Hopfin sistemi di equazioni differenziali ordinarie possa essere ridotta usando una opportuna tecnica formale nel calcolo delle derivate parziali di ordine superiore richiesto dal detto metodo.We outline how the complexity of the formulae by Hassard, Kazarinoff and Wan (1981) concerning the Hopf bifurcation in systems of ordinary differential equations can be reduced computing the pertinent higher-order partial derivatives in a suitable formal wa
A Continuous Parameter Version of Chacon's "Universal" Ergodic Theorem
No full textSi prova un teorema ergodico puntuale a parametro continuo del tipo
``universale'' di R. V. Chacon, per famiglie di operatori in che
non sono necessariamente semigruppi fortemente continui di operatori
lineari non-espansivi.This paper contains a continuous parameter pointwise ergodic theorem
of Chacon's ``universal'' type, for a family of operators in which
is not necessarily a strongly continuous contraction semigroup
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