Repositório Comunidade:
http://hdl.handle.net/10400.21/588
2018-03-24T06:18:30ZThe norm of the k-the derivative of the Chisymmetric power of an operator
http://hdl.handle.net/10400.21/8153
Título: The norm of the k-the derivative of the Chisymmetric power of an operator
Autor: Carvalho, Sónia; Freitas, Pedro J.
Resumo: In this paper, the exact value for the norm of directional derivatives, of all orders, for symmetric tensor powers of operators on finite dimensional vector spaces is presented. Using this result, an upper bound for the norm of all directional derivatives of immanants is obtained. This work is inspired in results by R. Bhatia, J. Dias da Silva, P. Grover, and T. Jain.2014-04-01T00:00:00ZThe k-th derivatives of the immanent and the chisymmetric power of an operator
http://hdl.handle.net/10400.21/8152
Título: The k-th derivatives of the immanent and the chisymmetric power of an operator
Autor: Carvalho, Sónia; Freitas, Pedro J.
Resumo: In recent papers, formulas are obtained for directional derivatives, of all orders, of the determinant, the permanent, the m-th compound map and the m-th induced power map. This paper generalizes these results for immanants and for other symmetric powers of a matrix.2014-04-01T00:00:00ZPropagation of regularity and positive definiteness: a constructive approach
http://hdl.handle.net/10400.21/8131
Título: Propagation of regularity and positive definiteness: a constructive approach
Autor: Buescu, Jorge; Paixão, António; Oliveira, Claudemir
Resumo: We show that, for positive de finite kernels, ifspecific forms of regularity (continuity, S-n-differentiability or holomorphy) hold locally on the diagonal, then they must hold globally on the whole domain of positive-definiteness. This local-toglobal propagation of regularity is constructively shown to be a consequence of the algebraic structure induced by the non-negativity of the associated bilinear forms up to order 5. Consequences of these results for topological groups and for positive definite and exponentially convex functions are explored.2018-01-01T00:00:00ZActive vibration attenuation in viscoelastic laminated composite panels using multiobjective optimization
http://hdl.handle.net/10400.21/8000
Título: Active vibration attenuation in viscoelastic laminated composite panels using multiobjective optimization
Autor: Luís, Ndilokelwa F.; Madeira, J. F. A.; Araújo, A. L.; Ferreira, A. J. M.
Resumo: The optimal design of viscoelastic laminated composite panels with active piezoelectric patches is addressed in this paper. Constrained optimization is conducted to determine optimal distributions of piezoelectric patches on the top and bottom surfaces of laminated plates with viscoelastic layers. The design variables are the number and position of these patches, and the objectives are the minimization of the number of patches, the maximization of the fundamental modal loss factor and the maximization of the fundamental natural frequency. The problem is solved using the Direct MultiSearch (DMS) solver for derivative-free MultiObjective Optimization (MOO). The objective functions are evaluated by a finite element model that was developed for laminated sandwich plates incorporating piezoelectric or viscoelastic layers. Trade-off Pareto optimal fronts and the respective optimal active patch configurations are obtained and the results are analyzed and discussed.2017-11-01T00:00:00Z