1,720,998 research outputs found
Shell theories arising as low-energy Γ-limit of 3D nonlinar elasticity
No full text1 online resource (PDF, 36 pages)Lewicka, Marta; Mora, Maria Giovanna; Pakzad, Mohammad Reza. (2008). Shell theories arising as low-energy Γ-limit of 3D nonlinar elasticity. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/179954
A note on convergence of low energy critical points of nonlinear elasticity functionals, for thin shells of arbitrary geometry
No full textWe prove that the critical points of the d nonlinear elasticity functional
over a thin shell of arbitrary geometry and of thickness , as well as the
weak solutions to the static equilibrium equations (formally the Euler
Lagrange equations associated to the elasticity functional) converge, in the
limit of vanishing thickness , to the critical points of the generalized von
Karman functional on the mid-surface, recently derived in [14].
This holds provided the elastic energy of the d deformations scale like and
the magnitude of the body forces scale like .Lewicka, Marta. (2008). A note on convergence of low energy critical points of nonlinear elasticity functionals, for thin shells of arbitrary geometry. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/45458
Scaling laws for non-Euclidean plates and the W^{2,2} isometric immersions of Riemannian metrics
No full textThis paper concerns the elastic structures which exhibit non-zero strain at free equilibria. Many growing tissues (leaves, flowers or marine invertebrates) attain complicated configurations during their free growth. Our study departs from the 3d incompatible elasticity theory, conjectured to explain the mechanism for the spontaneous formation of non-Euclidean metrics. Recall that a smooth Riemannian metric on a simply connected domain can be realized as the pull-back metric of an orientation preserving deformation if and only if the associated Riemann curvature tensor vanishes identically. When this condition fails, one seeks a deformation yielding the closest metric realization. We set up a variational formulation of this problem by introducing the non-Euclidean version of the nonlinear elasticity functional, and establish its -convergence under the proper scaling. As a corollary, we obtain new necessary and sufficient conditions for existence of a isometric immersion of a given d metric into .Lewicka, Marta; Pakzad, Reza. (2009). Scaling laws for non-Euclidean plates and the W^{2,2} isometric immersions of Riemannian metrics. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/51946
A nonlinear theory for shells with slowly varying thickness
Full text link1 online resource (PDF, 6 pages)Lewicka, Marta; Mora, Maria Giovanna; Pakzad, Mohammad Reza. (2008). A nonlinear theory for shells with slowly varying thickness. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/179960
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Existence and stability of viscoelastic shock profiles
No full textWe investigate existence and stability of
viscoelastic shock profiles for a class of planar models
including the incompressible shear case
studied by Antman and Malek-Madani.
We establish that the resulting equations fall
into the class of symmetrizable hyperbolic--parabolic systems,
hence spectral stability implies linearized
and nonlinear stability with sharp rates of decay.
The new contributions are treatment
of the compressible case,
formulation of a rigorous nonlinear stability theory,
including verification of stability of small-amplitude Lax shocks,
and the systematic incorporation in our investigations of
numerical Evans function computations determining stability of
large-amplitude and or nonclassical type shock profiles.Research of B.B. was partially supported
under NSF grant no. DMS-0801745.
Research of M.L. was partially supported
under NSF grants no. DMS-0707275 and DMS-0846996.
Research of K.Z. was partially supported
under NSF grants no. DMS-0300487 and DMS-0801745.Barker, Blake; Lewicka, Marta; Zumbrun, Kevin. (2010). Existence and stability of viscoelastic shock profiles. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/90859
The Foppl-von Karman equations for plates with incompatible strains
No full textWe provide a derivation of the Foppl-von Karman equations for the shape of and stresses in an elastic plate with residual strains. These might arise from a range of causes: inhomogeneous growth, plastic
deformation, swelling or shrinkage driven by solvent absorption. Our analysis gives rigorous bounds on the convergence of the three dimensional equations of elasticity to the low-dimensional description embodied in
the plate-like description of laminae and thus justifies a recent formulation of the problem to the shape of growing leaves. It also formalizes a procedure that can be used to derive other low-dimensional descriptions of active materials.M.L. was partially supported by the NSF grants DMS-0707275 and DMS-0846996 and by the Center for Nonlinear Analysis (CNA) under
the NSF grants 0405343 and 0635983. L.M. was partially supported by the Harvard NSF-MRSEC and the MacArthur Foundation. R.P. was partially supported by the NSF grant DMS-0907844.Lewicka, Marta; Mahadevan, L.; Pakzad, Reza. (2010). The Foppl-von Karman equations for plates with incompatible strains. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/58443
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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