Revistas académicas de la Universidad Católica del Norte
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Aproximación de los elementos propios asociados a matrices de gran tamaño
No full textUna gran variedad de problemas en las ciencias e ingeniería conducen a determinar ? ? ¢N, ? ? 0, tal que:A ? = ? ? ( 1)donde A es una matriz de gran tamaño y no necesariamente con una estructura conocida (simétrica, de banda, etc.) y ? es simple
On a new iteration for solving chandrasekhar's H-equations
No full textA new iteration for solving Chandrasekhar's H-Equation is given. Under certain assumptions the iteration converges without the usual positivity assumptions on the parameters·involved
Co-Adjoint representation and controllability
No full textLet ? an invariant control system over Lie group G The existence of a nontrivial simplectic orbit of G is analysed, so that the Hamiltonian system equivalent to ? via the co-adjoint representation, has a vector called simplectic. This allows the construction of a strictly increasing function over the positive trajectories of ?, determining sufficient conditions for the controllability of ? over G
Conjuntos de cantor dinámicamente definidos con HD = d ?]0,1[
No full textEn este trabajo. construimos una aplicación lineal por pedazos, L?1,?2 [0, 1] ? [0, 1] .donde ,?1, ?2 son parámetros reales, con la propiedad siguiente dado d ?]0. 1[ existe una curva v(?1) = (x ?1),y(?2)) tal que si vértices de L?1,?2 están sobre esta curva, entonces HD(K ?1,?2) = C(K ?1,?2) = d, donde H D es la dimensión de Hausdorff y C es la capacidad límite del conjunto de Cantor K ?1,?2 generado por L ?1,?
Uniqueness of blowing up solutions on the boundary in quasilinear elliptic equations with non homogeneous term in L?
No full textWe consider the quasilinear elliptic equation -?u + H(x, u, Du) = ƒ, in ? (EH)being ? ??N, N ?1, an open set with regular bounded boundary and f ? L?(?). In this work we obtain upper estimates of the growth, near to the boundary, for any classic solution of (EH) and the exact behavior for any non negative solution of (EH) verifiying Finally, we prove the uniqueness of blow-up solutions of (EH)
An Orlicz-Pettis theorem for conditionally convergent series
No full textin this note we define the idea of signed subseries convergent series in a normed linear space, and establish a result analogous to the Orlicz-Pettis theorem; namely, that weakly siqned subseries convergent series are norm signed subseries convergent
Creation of some structures in categories
No full textIn this paper, we study the creation property of projective and forgetful functors via generalized pullback (GPB) and generalized pushout (GPO) structures and also discus sorne general results
Controllability of two-dimensional bilinear systems
No full textFor bilincar control systems x = Ax + uBx, x ? R2 , A and B 2 x 2 matrices, necessary and sufficient conditions are given for the controllability on R2 -{0}. The method is through Lie theory, and follows the program outlined by this theory which consists in finding first the connected subgroups of the group Gl(2) of all invertible matrices which are transitive on R2 - {0}, and then look at the subsemigroups of these subgroups which are transitive. A detailed and nearly self contained exposition of the determination of the transitive subgroups is presented. It turns out that they are Gl+(2), Sl(2) and the commutative group of nonzero complex numbers. Controllability is analysed by considering these groups separately. In the case of Sl (2) the controllability is decided with the aid of a result of [15] about semigroups in semi-simple Lie groups. A self contained proof specific for Sl(2) is presented. This case by case analysis recovers the necessary and sufficient conditions given by Lepe and Joó and Tuan (see [10])
On the solution of a multiplicative inverse eigenvalue problem
No full textWe show that the solution of a particular multiplicative inverse eigenvalue problem is the set of zeros of the characteristic polynomial associated with the problem. Necessary conditions for a real solution are found