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NUMERICAL ANALYSIS OF A PROBLEM INVOLVING A VISCOELASTIC BODY WITH DOUBLE POROSITY

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Journal of Computational Mathematics 2022年第3期40卷 415-436页

作者： Noelia Bazarra Jose R.Fernandez MariCarme Leseduarte Antonio Magana Ramon Quintanilla departamento de Matematica Aplicada I Universidade de VigoETSI TelecomunicacionCampus As Lagoas Marcosende s/n36310 VigoSpain departamento de matematicas E.S.E.I.A.A.T.-U.P.C.Colom 1108222 TerrassaBarcelonaSpain

We study from a numerical point of view a multidimensional problem involving a viscoelastic body with two porous structures.The mechanical problem leads to a linear system of three coupled hyperbolic partial differential equations.Its corresponding variational formulation gives rise to three coupled parabolic linear equations.An existence and uniqueness result,and an energy decay property,are recalled.Then,fully discrete approximations are introduced using the finite element method and the implicit Euler scheme.A discrete stability property and a priori error estimates are proved,from which the linear convergence of the algorithm is derived under suitable additional regularity conditions.Finally,some numerical simulations are performed in one and two dimensions to show the accuracy of the approximation and the behaviour of the solution.

关键词： Viscoelasticity with double porosity Finite elements A priori estimates Numerical simulations

COMPLEXITY OF LARGE TIME BEHAVIOUR OF EVOLUTION EQUATIONS WITH BOUNdeD DATA

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Chinese Annals of Mathematics,Series B 2002年第2期23卷 293-310页

作者： J.L.VZQUEZ E.ZUAZUA departamento de matematicas Universidad AutonomaDepartamento de Matematica AplicadaUniversidadComplutense 28049MadridSpain28040 M

The authors study the asymptotic behaviour of solutions of the heat equation and a number of evolution equations using scaling techniques. It is proved that in the framework of bounded data stabilization need not occur and the general asymptotic behaviour is complex. This behaviour reflects for large times, even on compact sets, the complexity of the initial data at infinity.

关键词：复杂性大时间行为发展方程有界数据热方程 Omega极限双曲守恒定律半群收敛性

The McCoy Condition on Skew Poincaré-Birkhoff-Witt Extensions

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Communications in Mathematics and Statistics 2021年第1期9卷 1-21页

作者： Armando Reyes Camilo Rodriguez departamento de matematicas Universidad Nacional de ColombiaSede BogotaColombia

In this paper,we study the notion of McCoy ring over the class of non-commutative rings of polynomial type known as skew Poincare–Birkhoff–Witt extensions.As a consequence,we generalize several results about this no... 详细信息

关键词： McCoy ring Reversible ring Semicommutative ring Zip ring Skew Poincare–Birkhoff–Witt extension

On Rigid 2-Step Nilpotent Lie Algebras

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Algebra Colloquium 2018年第2期25卷 349-360页

作者： Maria Alejandra Alvarez departamento de matematicas Facultad de Ciencias Basicas Universidad de Antofagasta Casilla 170 Antofagasta Chile

在这笔记，我们认为 2 步 nilpotent 是谎言代数学并且在尺寸 n 的 2 步 nilpotent 谎言代数学的变化 Nn2 为这个班的刚硬给一个标准。我们使用这个标准证明在 Nn2 的每僵硬谎言代数学是不能分解的，除了 h3 和 h3 h3。

关键词：代数学谎言僵硬标准分解

Inference for a truncated positive normal distribution

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Applied Mathematics(A Journal of Chinese Universities) 2018年第2期33卷 163-176页

作者： Hector J.Gomez Neveka M.Olmos Hector Varela Heleno Bolfarine departamento de Ciencias matematicas y Ffsicas Facultad de IngenierlaUniversidad Catolica de TemucoTemucoChile departamento de matematicas Facultad de Ciencias BasicasUniversidad de AntofagastaAntofagastaChile departamento de Estatfstica IMEUniversidade de Sao PauloSao PauloBrazil

The main object of this paper is to study an extension of the half normal distribution defined by adding a positive truncation to it. The new model is more flexible than the half-normal distribution and contains the half normal distribution as a special case. Properties of this distribution, such as moments, hazard function and entropy are studied and parameters estimation is dealt with by using inoinents and inaxiinuin likelihood. A real data application indicates good fit performance of the new model when compared to other competitors in litera- tures.

关键词： half-normal distribution maximum likelihood truncation

SYNTHESIS AND PROPERTIES OF HOMOPOLYMER AND COPOLYMERS OBTAINED FROM 1-OCTAdeCENE WITH ZIRCONOCENE CATALYSTS

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Chinese Journal of Polymer Science 2000年第3期18卷 249-254页

作者： RaulQuijada JuanL.Guevara ReneRojas FrancoM.Rabagliati departamento de Ingenieria Quimica Facultad de Ciencias Fisicasy Matematicas Universidad de Chile Casilla 2777 Santiago ChileDepartamento de Ingenieria Quimica Facultad de Ciencias Fisicasy Matematicas Universidad de Chile Casilla 2777 Santiago ChileDepartamento de Ingenieria Quimica Facultad de Ciencias Fisicasy Matematicas Universidad de Chile Casilla 2777 Santiago ChileDepartamento Ciencias Quimicas Facultad Quimicay Biologia Universidad de Santiago de Chile Casilla 40 Santiago Chile

Studies related to the behavior of different metallocene catalysts for the homopolymerization of 1-octadecene andits copolymerization with ethylene will be presented. The metallocenes: rac-Et(Ind)_2ZrCl_2, rac-Me_2Si(Ind)_2ZrCl_2 andPh_2C(Flu)(Cp)ZrCl_2 were chosen for the homopolymerization study. They show important differences in catalytic activity athigh temperatures (≥70℃), with rac-Et(Ind)_2ZrCl_2 showing the highest activity. At lower temperatures (≤30℃) thedifferences are negligible. For the copolymerization of ethylene with 1-octadecene only the catalysts rac-Et(Ind)_2ZrCl_2 andrac-Me_2Si(Ind)_2ZrCl_2 were studied. The results show that their catalytic activity is just like that for the homopolymerizationof 1-octadecene, with higher activity for the metallocene with the Et-bridged catalyst. ^(13)C-NMR analysis shows that thecomposition of the copolymerization products depends on the catalytic systems. Copolymers obtained with rac-Me_2Si(Ind)_2ZrCl_2 have greater comonomer incorporation. Thermal analysis shows that poly-1-octadecene synthesized withthe catalyst rac-Et(Ind)_2ZrCl_2 is very dependent on the polymerization temperature. The homopolymer obtained at 70℃presents two endothermal peaks at 41℃ and 53℃, as compared with the one obtained at 30℃ which presents one wider peakwith a maximum at 67℃. For the catalyst rac-Me_2Si(Ind)_2ZrCl_2 this trend is not observed. The type of metallocene and thereaction time do not significantly change the intrinsic viscosity, but the polymerization temperature changes it drastically,giving higher values at lower temperature. Viscosity measurements on the copolymers show that an increase of comonomerconcentration in the feed reduces the molecular weight of the copolymer, and it was also found that for homopolymer, themolecular weight is independent of the catalytic systems.

关键词： Homopolymerization Copolymerization Metallocene Catalytic activity Poly-l-octadecene

Maschke Type Theorems for Weak Hopf Quasigroups

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Algebra Colloquium 2020年第2期27卷 213-230页

作者： J.N.Alonso Alvarez J.M.Fernández Vilaboa R.González Rodríguez departamento de matematicas Vniversidade de Vigo Campus Universitario Lagoas-MarcosendeE-36280 VigoSpain departamento de matematicas Universidade de Santiago de Compostela E-15771 Santiago de CompostelaSpain departamento de Matematica Aplicada II Universidade de Vigo Campus Universitario Lagoas-MarcosendeE-36310 VigoSpain

In this paper we give necessary and sufficient conditions for a comodule magma over a weak Hopf quasigroup to have a total integral,thus extending the theories developed in the Hopf algebra,weak Hopf algebra and non-associative Hopf algebra contexts.From this result we also deduce a version of Maschke’s theorems for right(H,B)-Hopf triples associated to a weak Hopf quasigroup H and a right H-comodule magma B.

关键词： (weak)Hopf algebra (weak)Hopf quasigroup integral Maschke theorem

Harmonic functions with boundary values on Herz spaces

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Frontiers of Mathematics in China 2013年第6期8卷 1265-1274页

作者： Martha GUZMAN-PARTIDA departamento de matematicas Universidad de Sonora Rosales y Luis Encinas HermosilloSonora 83000 Mexico

We discuss continuity of the Poisson transform on Herz spaces Bp as well as its action on weighted versions of these sets. We also consider Banach- valued versions of Herz spaces and study some of their properties.

关键词： Herz space Poisson transform

L^1→L^q Poincare Inequalities for 0

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Acta Mathematica Sinica,English Series 2002年第1期18卷 1-20页

作者： PEREZ Carlos departamento dr matematicas. Universidad Autónoma de Madrid. 28049 Madrid. Spain

Civen two doubling measures μ and v in a metric apace (S.p)of homogeneous type. let B_0 S be a given ball. It has been a well-known result bv now (see)[1 4])theat the validity of an L^1→L^1 Poincaré inequality of the following form: f_B|f-f_B|dv≤cr(B)f_Bgdμ. for all metric balls B B_0 S, implies a variant of representation formula of fractonal integral type: |f(x)-f_(B(11))|≤C integral from n=B_(11) g(y)p(x, y)/μ(B(x, p(x, y)))dμ(y)+C(r(B_0))/(μ(B_0))integral from n=B_0 g(y)dμ(y). One of the main results of this paper shows that an L^1 to L^q Poincaré inequality for some 01, i.e.. (f_B|f-f_B|~q dv)^(1/q)≤cr(B) f_B gdμ, for all metric balls B B_0. will suffice to imply the above representation formula. As an immediate corollary, we can show that the weak-type condition. sup_(λ>0)(λv({x ∈ B:|f(x)-f_B|>λ}))/v(B)≤Gr (B)f_B gdμ. also implies the same formula. Analogous theorems related to high-order Poincaréinequalities and Sobolev spaces in metric spaces are also proved.

关键词： Sobolev spaces Representation formulas High-order derivatives Vector fields Metric spaces Polynomials Doubling measures Poincare inequalities