The Index of Cusp Operators on Manifolds with Corners

We recall a Fredholm criterion for fully elliptic cusp(pseudo)differential operators on a compact manifold with corners ofarbitrary codimension, acting on suitable Sobolev spaces. Then we give aformula for the index in terms of regularized `trace' functionalssimilar to the residue trace of Wodzicki and Guillemin.     

Submanifolds in the Context of Infinite Dimensional Manifolds with Corners

In this paper we introduce new definitions of submanifold and immersion in the context of infinite dimensional manifolds with corners. We show that they are the natural concepts in this context by giving positive answers to the problems of transitivity of submanifolds, inverse image of submanifolds and transversality, the problem of good immersion in quadrants of Banach spaces and the relation between a map being differentiable and its graph being a submanifold.     

Hyperbolic Distortion of Conformal Maps at Corners

We consider conformal self-maps φ of the unit disk onto simply connected domains. We assume φ is continuous in a neighborhood of a point , with φ(ζ) of modulus one, and that has a corner at φ(ζ). We prove that the modulus of the hyperbolic derivative of φ tends to a limit along certain simple curves in the disk that end at ζ non-tangentially. Moreover, we prove that the value of this limit depends only on the geometry of the corner and on the angle of approach to ζ. Our proof is based on a constructive approximation of the domain by more special domains. This research in its different stages was supported partially by MEC grants MTM2006-14449-C02-02 and MTM2006-26627-E (Acciones Complementarias), Spain; and also by “Ingenio Mathematica (i-MATH)” CSD2006-00032 (Consolider—Ingenio 2010), from MCyT, Spain; as well as by the MEC/Fulbright Fellowship 2007-0752.     

A Curved Macro-Element for Cracks and Corners

This note provides an extension of the quarter-point type offinite elements which are widley used in the solution of ellipticdifferential equations in regions with re-entrant corners. Itis shown how curved two or three-dimensional elements can bedevised that have the desired singular behaviour and permitarbitrary mesh refinement in the neighbourhood of the re-entrantcorner thus facilitating the attainment of high resolutionsapproximations. It is also shown how macro-elements can be usedto estimate the most advantageous size to use for the singularelements.     

Interlaminar Stresses at Corners of Laminate Reinforcements

For inplane loaded plates the use of two laminate patches which are attached symmetrically to a base laminate with respect to the out-of-plane direction is a possibility to reinforce a highly stressed region. But corners at the patches' boundaries constitute a source for stress localizations. The expedient knowledge of the local mechanical inplane fields at such corners can be obtained with the boundary finite element method (BFEM). In order to investigate the intrinsically three-dimensional nature of the laminate corner setup the gradients of the inplane fields are readily evaluated since they are provided by the BFEM in a semi-analytical way. The interlaminar stresses inside the plate are retrieved by equilibrium considerations on a ply-by-ply basis. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Diffraction at Corners for the Wave Equation on Differential Forms

Our study of a basic model for incompressible two-phase flows with phase transitions consistent with thermodynamics in the case of constant but non-equal densities of the phases, begun in [23 Prüss , J. , Shimizu , S. (2012). On well-posedness of incompressible two-phase flows with phase transition: The case of non-equal densities. J. Evol. Eqs. 12:917–941.[Crossref], [Web of Science ®] , [Google Scholar]], is continued. We extend our well-posedness result to general geometries, study the stability of the equilibria of the problem, and show that a solution which does not develop singularities exists globally. Moreover, if its limit set contains a stable equilibrium it converges to this equilibrium as time goes to infinity, in the natural state manifold for the problem in an L _p -setting.     

K-Theory of the Indicial Algebra of a Manifold with Corners

We compute the K-theory, groups of the C ^*-algebra of the groupoid of a manifold with corners, in which the analytic index takes its values.     

On the Solution of the Stokes Equation on Regions with Corners

The detailed behavior of solutions to Stokes equations on regions with corners has been historically difficult to characterize. The solutions to Stokes equations on regions with corners are known to develop singularities in the vicinity of corners; in particular, the solutions are known to have infinite oscillations along almost every ray that meet at the corner. While the nature of singularities for the differential equation have been analyzed in great detail, very little is known about the nature of singularities for the corresponding integral equations. In this paper, we observe that, when the Stokes equation is formulated as a boundary integral equation, the solutions are representable by rapidly convergent series of the form , where t is the distance from the corner and the parameters μ_j, β_j are real, and are determined via an explicit formula depending on the angle at the corner. In addition to being analytically perspicuous, these representations lend themselves to the construction of highly accurate and efficient numerical discretizations, significantly reducing the number of degrees of freedom required for the solution of the corresponding integral equations. The results are illustrated by several numerical examples. © 2020 Wiley Periodicals LLC     

Lipschitz Domains,Domains with Corners,and the Hodge Laplacian

ABSTRACT

We define self-adjoint extensions of the Hodge Laplacian on Lipschitz domains in Riemannian manifolds, corresponding to either the absolute or the relative boundary condition, and examine regularity properties of these operators' domains and form domains. We obtain results valid for general Lipschitz domains, and stronger results for a special class of “almost convex” domains, which apply to domains with corners.     

Embedding Semigroups into Idempotent Generated Ones

We present a concrete model of the embedding due to Pastijn and Yan of a semigroup S into an idempotent generated semigroup now in terms of a Rees matrix semigroup over S¹. The paper starts with a comparison of the two embeddings. Studying the properties of this embedding, we prove that it is functorial. We show that a number of usual semigroup properties is preserved by this embedding, such as periodicity, finiteness, the cryptic property, regularity, complete semisimplicity and various local properties, but complete regularity is not one of them.     

Nonobtuse Tetrahedral Partitions that Refine Locally Towards Fichera-Like Corners

Linear tetrahedral finite elements whose dihedral angles are all nonobtuse guarantee the validity of the discrete maximum principle for a wide class of second order elliptic and parabolic problems. In this paper we present an algorithm which generates nonobtuse face-to-face tetrahedral partitions that refine locally towards a given Fichera-like corner of a particular polyhedral domain. The first author was supported by the Swedish Foundation for Strategic Research, the second author was supported by Grant No. 49051 of the Academy of Finland, the third author was supported by Grant No. A 1019201 of the Academy of Sciences of the Czech Republic and by Institutional Research Plan AV0Z 10190503.     

局部标准2-torus作用和带角流形

给出了光滑闭流形上的光滑2-torus作用是局部标准的一个充要条件,即其轨道空间是好的带角流形,并且对轨道空间中的每一个点,其迷向子群的秩等于该点的余维数.     

Enumeration of Lozenge Tilings of Hexagons with Cut-Off Corners

Motivated by the enumeration of a class of plane partitions studied by Proctor and by considerations about symmetry classes of plane partitions, we consider the problem of enumerating lozenge tilings of a hexagon with “maximal staircases” removed from some of its vertices. The case of one vertex corresponds to Proctor's problem. For two vertices there are several cases to consider, and most of them lead to nice enumeration formulas. For three or more vertices there do not seem to exist nice product formulas in general, but in one special situation a lot of factorization occurs, and we pose the problem of finding a formula for the number of tilings in this case.     

On the Similarity of Some Differential Operators to Self-Adjoint Ones

The paper is devoted to the study of the similarity to self-adjoint operators of operators of the form , in the space with weight . As is well known, the answer to this problem in the case is positive; it was obtained by using delicate methods of the theory of Hilbert spaces with indefinite metric. The use of a general similarity criterion in combination with methods of perturbation theory for differential operators allows us to generalize this result to a much wider class of weight functions .     

Stress Singularities in Viscoelastic Media 2. Plane-Strain Stress Singularities at Corners

The stress singularities that evolve at the corner of a notchedviscoelastic angular plate subject to mode I deformation isdiscussed when prescribed, but arbitrary, displacements aresymmetrically applied to both radial edges of the sector. Thesolution procedure, based on Laplace and Mellin transforms (withtransform parameters p and s, respectively), leads to an eigenvalueproblem in the complex p-plane, which is dependent on Poisson'sratio and characterizes the singular behaviour of the stressfields. Although simple solutions to the transcendental eigenequationare not available, the real-time evolution of the stress concentrationsis obtained by monitoring a particular branch of the eigenvalueequation as it moves in the complex p-plane. A correspondingpath is traced in an appropriately cut strip in the s-plane,in which solutions to the eigenequation are single-valued. Analyticcontinuation in the p-plane thus allows the Laplace and Mellininversions to be performed and the real-time behaviour of theplane-stress components to be expressed as contour integralswithin the strips in the complex s-plane. Cast in this form,the stress components are evaluated numerically when the viscoelasticmaterial is represented as a standard linear solid. Their dependenceon the angular variation within the plate, the applied load,and the effects of the viscoelastic material properties is exhibitedfor a number of situations, and in each case contrasted withshort- and long-time asymptotic curves based on Tauberian theorems.     

The Johnson-Schechtman space has the 6-bounded approximation property

In 2001 G. Godefroy proved that a subspace XJS of c₀ constructed by W.B. Johnson and G. Schechtman in 1996 has the λ-bounded approximation property with λ?8. This paper slightly improves Godefroy's proof establishing that λ?6.