The analyticity of a generalized Ruelle’s operatorBoletim da Sociedade Brasileira de Matemática - Bulletin/Brazilian Mathematical Society - Tập 45 - Trang 53-72 - 2014
Eduardo Antônio da Silva, Raderson Rodrigues da Silva, Rafael Rigão Souza
In this work we propose a generalization of the concept of Ruelle’s operator for one dimensional lattices used in thermodynamic formalism and ergodic optimization, which we call generalized Ruelle’s operator. Our operator generalizes both the Ruelle operator proposed in [2] and the Perron Frobenius operator defined in [7]. We suppose the alphabet is given by a compact metric space, and consider a ...... hiện toàn bộ
Numerical study of an equation related to wave propagationBoletim da Sociedade Brasileira de Matemática - Bulletin/Brazilian Mathematical Society - Tập 10 - Trang 57-69 - 1979
C. A. de Moura, M. A. Raupp, J. C. Barbetta
We discuss two algorithms for the computation of approximate solutions of a generalization of the so-called Benjamin-Bona-Mahony equation, which is a model proposed to describe unidirectional propagation of long water waves. Both schemes discussed are quadratically convergent with respect to Δt in theH
1-norm. They use the Galerkin method for the space variable in such a way that t...... hiện toàn bộ
Framed Surfaces in the Euclidean SpaceBoletim da Sociedade Brasileira de Matemática - Bulletin/Brazilian Mathematical Society - Tập 50 - Trang 37-65 - 2018
Tomonori Fukunaga, Masatomo Takahashi
A framed surface is a smooth surface in the Euclidean space with a moving frame. The framed surfaces may have singularities. We treat smooth surfaces with singular points, that is, singular surfaces more directly. By using the moving frame, the basic invariants and curvatures of the framed surface are introduced. Then we show that the existence and uniqueness for the basic invariants of the framed...... hiện toàn bộ
A Regularity Criterion of Weak Solutions to the 3D Boussinesq EquationsBoletim da Sociedade Brasileira de Matemática - Bulletin/Brazilian Mathematical Society - Tập 51 - Trang 513-525 - 2019
Sadek Gala, Maria Alessandra Ragusa
The paper deals with the regularity criteria for the weak solutions to the 3D Boussinesq equations in terms of the partial derivatives in Besov spaces. It is proved that the weak solution $$(u,\theta )$$ becomes regular provided that $$\begin{aligned} (\nabla _{h}{\widetilde{u}},\nabla _{h}\theta )\in L^{1}(0,T;\overset{\cdot }{B }_{\infty ,\infty }^{0}({\mathbb {R}}^{3})) \end{aligned}$$Our resul...... hiện toàn bộ
Lines of curvature on surfaces immersed in ℝ4Boletim da Sociedade Brasileira de Matemática - Bulletin/Brazilian Mathematical Society - Tập 28 - Trang 233-251 - 1997
Carlos Gutierrez, Irwen Guadalupe, Renato Tribuzy, Víctor Guíñez
The differential equation of thelines of curvature for immersions of surfaces into ℝ4 is established. It is shown that, for a class of generic immersions of a surface into ℝ4 in theC
r
-topology,r≥4, all of the umbilic points are locally topologically stable. This type of umbilic points is described.
Norm optimization problem for linear operators in classical Banach spacesBoletim da Sociedade Brasileira de Matemática - Bulletin/Brazilian Mathematical Society - Tập 40 - Trang 417-431 - 2009
Daniel Pellegrino, Eduardo V. Teixeira
The main result of the paper shows that, for 1 < p < ∞ and 1 ≤ q < ∞, a linear operator T: ℓ
p
→ ℓ
q
attains its norm if, and only if, there exists a not weakly null maximizing sequence for T (counterexamples can be easily constructed when p = 1). For 1 < p ≠ q < ∞, as a consequence of the previous result we show that any not we...... hiện toàn bộ
Local Null Controllability of a 1D Stefan ProblemBoletim da Sociedade Brasileira de Matemática - Bulletin/Brazilian Mathematical Society - Tập 50 - Trang 745-769 - 2018
E. Fernández-Cara, F. Hernández, J. Límaco
The purpose of this article is to give a new proof of a null controllability result for a 1D free-boundary problem of the Stefan kind for a heat PDE. We introduce a method based on local inversion that, in contrast with other previous arguments, does not rely on any compactness property and can be generalized to higher dimensions.