1,722,049 research outputs found
Evolutionary models for giant extragalactic HII regions at different metallicities
No full textThis is an electronic version of an article published in Astronomy and Astrophysics, Supplement Series. García-Vargas, M.L., Bressan, A. and A.I. Díaz. Evolutionary models for giant extragalactic HII regions at different metallicities. Astronomy and Astrophysics, Supplement Series 112 (1995): 13-3
Predicted emission lines from giant HII regions ionized by aging star clusters
No full textThis is an electronic version of an article published in Astronomy and Astrophysics, Supplement Series. García-Vargas, M.L., Bressan, A. and A.I. Díaz. Predicted emission lines from giant HII regions ionized by aging star clusters. Astronomy and Astrophysics 112, Supplement Series (1995): 35-7
Isogeometric regular discretization for the Stokes problem
Full text linkThe inf-sup stability and optimal convergence of an isogeometric C 1 discretization for the Stokes problem are shown. In this discretization the velocities are the pushforward through the geometrical map of cubic C1 non-uniform rational B-spline (NURBS) functions and the pressures are the pushforward of quadratic C1 NURBS. This paper follows the work in Bazilevs et al. (2006, Math. Models Methods Appl. Sci., 16, 1031-1090) where the authors showed the numerical result of this discretization and proved the inf-sup stability for C0 NURBS functions. The use of more regular functions is useful to decrease the degrees of freedom and thus the computational cost. The analysis is performed by means of the Verfürth trick, the macro-element technique, some approximation properties and the inf-sup condition for tensor products of B-spline spaces. © 2010 The author
Some properties of LR-splines
Full text linkRecently a new approach to piecewise polynomial spaces generated by B-spline has been presented by T. Dokken, T. Lyche and H.F. Pettersen, namely Locally Refined splines. In their recent work (Dokken et al., 2013) they define the LR B-spline collection and provide tools to compute the space dimension. Here different properties of the LR-splines are analyzed: in particular the coefficients for polynomial representations and their relation with other properties such as linear independence and the number of B-splines covering each element. © 2013 Elsevier B.V
Spin physics. Polarized electron sources and polarimeters. Proceedings, 16th International Symposium, SPIN 2004, Trieste, Italy, October 10-16, 2004, and Workshop, PESP 2004, Mainz, Germany, October 7-9, 2004
No full textNo Abstract, preface to the publicatio
Impact of metallicity on the evolution of young star clusters
No full textWe discuss the results of N-body simulations of intermediate-mass young star clusters (SCs) with three different metallicities (Z = 0.01, 0.1 and 1 Z(circle dot)), including metallicity-dependent stellar evolution recipes and metallicity-dependent prescriptions for stellar winds and remnant formation. The initial half-mass relaxation time of the simulated young SCs (similar to 10 Myr) is comparable to the lifetime of massive stars. We show that mass-loss by stellar winds influences the reversal of core collapse and the expansion of the half-mass radius. In particular, the post-collapse re-expansion of the core is weaker for metal-poor SCs than for metal-rich SCs, because the former lose less mass (through stellar winds) than the latter. As a consequence, the half-mass radius expands faster in metal-poor SCs. The difference in the half-light radius between metal-poor SCs and metal-rich SCs is (up to a factor of 2) larger than the difference in the half-mass radius
Well-posedness of a model for the growth of tree stems and vines
No full textThe paper studies a PDE model for the growth of a tree stem or a vine, having the form of a differential inclusion with state constraints. The equations describe the elongation due to cell growth, and the response to gravity and to external obstacles. The main theorem shows that the evolution problem is well posed, until a specific "breakdown configuration" is reached. A formula is proved, characterizing the reaction produced by unilateral constraints. At a.e. time t, this is determined by the minimization of an elastic energy functional under suitable constraints
On the uniqueness of response stress functionals for purely mechanical continuous media, from the Mach Painleve point of view
No full textThis extended memoir is devoted to the axiomatics of media which respond to stresses (and no
higher-order generalized forces). It therefore deals especially with the notion of contact forces and
raises the question of whether these can be defined in terms of forces at-a-distance and kinematic
notions along a path paved by Ernst Mach and Paul Painleve almost a century ago. This can also ́
be regarded as a contribution to a program proposed by C. A. Truesdell concerning the search
for constitutive functionals (here the stress functional) which are compatible with a given class of
thermomechanical processes
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