35,038 research outputs found
Accurate Sharp Interface Scheme for Multimaterials
No full textWe present a method to capture the evolution of a contact discontinuity separating two different material. A locally non-conservative scheme allows an accurate and stable simulation while the interface is kept sharp. Numerical illustrations include problems involving fluid and elastic problems
A sharp Trudinger-Moser type inequality for unbounded domains in R^n
No full textThe Trudinger-Moser inequality states that for functions u in the Sobolev space H^1,n
over a bounded domain with a certain exponential integral is bounded by a constant depending on the domain, but not on u. Recently, the second author has shown that for n = 2 the bound the constant is independent of the domain if the Dirichlet norm is replaced by the full Sobolev norm,
We extend here this result to arbitrary dimensions n > 2. Also, we prove that on all of R^n the corresponding supremum is attained. The proof is based on a blow-up procedure
Taxonomic revision of species in the New Zealand endemic genera Peniticus Sharp, 1876 and Pilacolaspis Sharp, 1886 (Coleoptera: Chrysomelidae)
No full textIn this work, two endemic genera of Eumolpinae from New Zealand, Pilacolaspis Sharp, 1886 and Peniticus Sharp, 1876, are revised for the first time since the description of their constituent species in the late 19th and early 20th centuries. The five taxa of Pilacolaspis are considered to comprise two species, P. huttoni (Broun, 1880) (=P. wakefieldi Sharp, 1886 n. syn. =P. rugiventris Broun, 1914 n. syn.) and P. latipennis Broun, 1912 (=P. angulatus Broun, 1912 n. syn.), with allopatric distributions in the Canterbury/Otago lowlands and the Marlborough areas around the Kaikouras, respectively. The following five species are recognised in Peniticus, one of which is new: P. antiquus Sharp, 1876, P. wallacei Broun, 1909, P. microreticulatus sp. nov., P. suffusus Sharp, 1876 (=P. robustus Sharp, 1880 n. syn.) and P. plicatus Broun, 1921. A key to the New Zealand genera of Eumolpinae and the species of Pilacolaspis and Peniticus is provided.This work would have not been possible without support from a Salvador de Madariaga mobility scholarship from the Spanish Ministry of Science, Innovation and Universities (PRX18/00219), as well as research grant CGL2017‐83324‐P of the Agencia Estatal de Investigación from the same Ministry, with contribution from the European Commission RDF
Lagrangian sharp interface schemes for multimaterials
No full textWe present multi-material simulations in the Lagrangian framework. The methods employed are based on classical Godunov-like methods that are adapted to treat the case of interfaces separating different materials. In the models considered the gas, liquids or elastic materials are described by specific constitutive laws, but the governing equations are the same. Examples of gas-gas and elastic-elastic material interactions are presented
Sharp regularity estimates for second order fully nonlinear parabolic equations
No full textWe prove sharp regularity estimates for viscosity solutions of fully nonlinear parabolic equations of the form (Formula Presented.)where F is elliptic with respect to the Hessian argument and f∈ Lp , q(Q1). The quantity Ξ(n,p,q):=np+2q determines to which regularity regime a solution of (Eq) belongs. We prove that when 1 < Ξ (n, p, q) < 2 - ϵF, solutions are parabolically α-Hölder continuous for a sharp, quantitative exponent 0 < α(n, p, q) < 1. Precisely at the critical borderline case, Ξ (n, p, q) = 1 , we obtain sharp parabolic Log-Lipschitz regularity estimates. When 0 < Ξ (n, p, q) < 1 , solutions are locally of class C1+σ,1+σ2 and in the limiting case Ξ (n, p, q) = 0 , we show parabolic C1 , Log-Lip regularity estimates provided F has “better” a priori estimates.Fil: Da Silva, Joao Vitor. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Matemática; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Teixeira, Eduardo. Universidade Federal Do Ceará; Brasi
Sharp partial order and linear autonomous systems
No full text[EN] This paper deals with autonomous linear systems and the sharp partial order. Given an autonomous linear system, we find another system, which is related to the first one by means of the sharp partial order. This relation can be interpreted in different ways: as a perturbation or as a projection of the initial system. Both points of view allow us to work with a new system with some previously selected behaviour. The solutions of the two systems are related via a matrix that gives the gap between them. We design some algorithms and analize their performance with numerical examples.This research was partially supported by Ministerio de Economia, Industria y Competitividad of Spain (Red de Excelencia MTM2017-90682-REDT) and by Universidad de Buenos Aires (EXP-UBA: 13.019/2017, 20020170100350BA).Herrero Debón, A.; Thome, N. (2020). Sharp partial order and linear autonomous systems. Applied Mathematics and Computation. 366:1-11. https://doi.org/10.1016/j.amc.2019.124736S111366Cvetković-Ilić, D. S., Mosić, D., & Wei, Y. (2015). Partial orders on B(H). Linear Algebra and its Applications, 481, 115-130. doi:10.1016/j.laa.2015.04.025Hartwig, R. E., & Spindelböck, K. (1983). Matrices for whichA∗andA†commute. Linear and Multilinear Algebra, 14(3), 241-256. doi:10.1080/03081088308817561Makarenkov, O., & Nistri, P. (2008). Periodic solutions for planar autonomous systems with nonsmooth periodic perturbations. Journal of Mathematical Analysis and Applications, 338(2), 1401-1417. doi:10.1016/j.jmaa.2007.05.086Malik, S. B., Rueda, L., & Thome, N. (2013). Further properties on the core partial order and other matrix partial orders. Linear and Multilinear Algebra, 62(12), 1629-1648. doi:10.1080/03081087.2013.839676STYAN, G. P. H. (1970). Notes on the distribution of quadratic forms in singular normal variables. Biometrika, 57(3), 567-572. doi:10.1093/biomet/57.3.56
Railroad Car - Export
No full textNumber 4, manufactured for Ferrocarril del Pacifico. Exterior view. first class passenger car being loaded by crane aboard Pennsylvania Railroad gondola car. Locomotive #Y-52 present. 8x10 n
Positive definiteness of the blended force-based quasicontinuum method
No full textThe development of consistent and stable quasicontinuum models for multidimensional crystalline solids remains a challenge. For example, proving the stability of the force-based quasicontinuum (QCF) model [M. Dobson and M. Luskin, M2AN Math. Model. Numer. Anal., 42 (2008), pp. 113--139] remains an open problem. In one and two dimensions, we show that by blending atomistic and Cauchy--Born continuum forces (instead of a sharp transition as in the QCF method) one obtains positive-definite blended force-based quasicontinuum (B-QCF) models. We establish sharp conditions on the required blending width
Sharp L-p-L-q estimates for Bochner-Riesz operators of negative index in R-n, n >= 3
No full textIn this note we study L-p-L-q estimates for the Bochner-Riesz operators T-alpha, alpha > 0 of negative order in R-n, n greater than or equal to 3. (C) 2004 Elsevier Inc. All rights reserved.X115sciescopu
Railroad Car - Export
No full textNumber 4, manufactured for Ferrocarril del Pacifico. Exterior view. first class passenger car being loaded by crane aboard Pennsylvania Railroad gondola car. Locomotive #Y-52 present. 8x10 n
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