Xem 1-20 trên 112 kết quả Manifolds
  • The Ricci flow was introduced by Hamilton in 1982 [H1] in order to prove that a compact three-manifold admitting a Riemannian metric of positive Ricci curvature is a spherical space form. In dimension four Hamilton showed that compact four-manifolds with positive curvature operators are spherical space forms as well [H2]. More generally, the same conclusion holds for compact four-manifolds with 2-positive curvature operators [Che]. Recall that a curvature operator is called 2-positive, if the sum of its two smallest eigenvalues is positive. ...

    pdf20p dontetvui 17-01-2013 19 6   Download

  • We prove that knowing the lengths of geodesics joining points of the boundary of a two-dimensional, compact, simple Riemannian manifold with boundary, we can determine uniquely the Riemannian metric up to the natural obstruction. 1. Introduction and statement of the results Let (M, g) be a compact Riemannian manifold with boundary ∂M . Let dg (x, y) denote the geodesic distance between x and y. The inverse problem we address in this paper is whether we can determine the Riemannian metric g knowing dg (x, y) for any x ∈ ∂M , y ∈ ∂M . ...

    pdf19p noel_noel 17-01-2013 19 3   Download

  • Annals of Mathematics This paper is the third in a series where we describe the space of all embedded minimal surfaces of fixed genus in a fixed (but arbitrary) closed 3-manifold. In [CM3]–[CM5] we describe the case where the surfaces are topologically disks on any fixed small scale. Although the focus of this paper, general planar domains, is more in line with [CM6], we will prove a result here (namely, Corollary III.

    pdf51p tuanloccuoi 04-01-2013 17 7   Download

  • Classical differential geometry is the approach to geometry that takes full advantage of the introduction of numerical coordinates into a geometric space. This use of coordinates in geometry was the essential insight of Rene Descartes that allowed the invention of analytic geometry and paved the way for modern differential geometry. The basic object in differential geometry (and differential topology) is the smooth manifold. This is a topological space on which a sufficiently nice family of coordinate systems or "charts" is defined.

    pdf0p taurus23 26-09-2012 30 6   Download

  • This paper is the first in a series where we describe the space of all embedded minimal surfaces of fixed genus in a fixed (but arbitrary) closed Riemannian 3-manifold. The key for understanding such surfaces is to understand the local structure in a ball and in particular the structure of an embedded minimal disk in a ball in R3 (with the flat metric). This study is undertaken here and completed in [CM6]. These local results are then applied in [CM7] where we describe the general structure of fixed genus surfaces in 3-manifolds. There are two local models for...

    pdf43p tuanloccuoi 04-01-2013 33 6   Download

  • In this paper we describe the propagation of C ∞ and Sobolev singularities for the wave equation on C ∞ manifolds with corners M equipped with a Rie2 1 mannian metric g. That is, for X = M × Rt , P = Dt − ∆M , and u ∈ Hloc (X) solving P u = 0 with homogeneous Dirichlet or Neumann boundary conditions, we show that WFb (u) is a union of maximally extended generalized broken bicharacteristics. This result is a C ∞ counterpart of Lebeau’s results for the propagation of analytic singularities on real analytic manifolds with...

    pdf65p dontetvui 17-01-2013 30 6   Download

  • Hot Runner Technology has many contents: Introduction, Basic Aspects of Heat Technology, Introduction of Hot Runner Components, Heating of Hot Runner Manifold Blocks, Heating of Hot Runner Nozzles, Measurement and Control of Temperature, Material Behavior under Mechanical Load, Corrosion and Wear, Screw Connections and Material Selection for Elevated Temperatures, Basic Aspects of Plastics Technology, Maintenance and Storage of Hot Runner Molds.

    pdf245p chipnhohauinqh 22-04-2014 28 6   Download

  • Tuyển tập các báo cáo nghiên cứu khoa học ngành toán học được đăng trên tạp chí toán học quốc tế đề tài: Semi-invariant warped product submanifolds of cosymplectic manifolds

    pdf24p sting03 04-02-2012 21 5   Download

  • For each k ∈ Z, we construct a uniformly contractible metric on Euclidean space which is not mod k hypereuclidean. We also construct a pair of uniformly contractible Riemannian metrics on Rn , n ≥ 11, so that the resulting manifolds Z and Z are bounded homotopy equivalent by a homotopy equivalence which is not boundedly close to a homeomorphism. We show that for these lf spaces the C ∗ -algebra assembly map K∗ (Z) → K∗ (C ∗ (Z)) from locally finite K-homology to the K-theory of the bounded propagation algebra is not a monomorphism ...

    pdf21p tuanloccuoi 04-01-2013 12 5   Download

  • Holomorphic disks and topological invariants for closed three-manifolds ´ ´ ´ By Peter Ozsvath and Zoltan Szabo* Abstract The aim of this article is to introduce certain topological invariants for closed, oriented three-manifolds Y , equipped with a Spinc structure. Given a Heegaard splitting of Y = U0 ∪Σ U1 , these theories are variants of the Lagrangian Floer homology for the g-fold symmetric product of Σ relative to certain totally real subspaces associated to U0 and U1 . 1. Introduction Let Y be a connected, closed, oriented three-manifold, equipped with a Spin structure s. ...

    pdf133p tuanloccuoi 04-01-2013 23 5   Download

  • The goal of this work is to give a precise numerical description of the K¨hler cone of a compact K¨hler manifold. Our main result states that the a a K¨hler cone depends only on the intersection form of the cohomology ring, the a Hodge structure and the homology classes of analytic cycles: if X is a compact K¨hler manifold, the K¨hler cone K of X is one of the connected components of a a the set P of real (1, 1)-cohomology classes {α} which are numerically positive on analytic cycles, i.e. Y αp 0 for every irreducible analytic...

    pdf29p tuanloccuoi 04-01-2013 20 5   Download

  • The space of embedded minimal surfaces of fixed genus in a 3-manifold II; Multi-valued graphs in disks By Tobias H. Colding and William P. Minicozzi II* 0. Introduction This paper is the second in a series where we give a description of the space of all embedded minimal surfaces of fixed genus in a fixed (but arbitrary) closed 3-manifold. The key for understanding such surfaces is to understand the local structure in a ball and in particular the structure of an embedded minimal disk in a ball in R3 . We show here that if the curvature of such a disk...

    pdf25p tuanloccuoi 04-01-2013 21 5   Download

  • We define and study an algebra Ψ∞ (M0 ) of pseudodifferential opera1,0,V tors canonically associated to a noncompact, Riemannian manifold M0 whose geometry at infinity is described by a Lie algebra of vector fields V on a compactification M of M0 to a compact manifold with corners. We show that the basic properties of the usual algebra of pseudodifferential operators on a compact manifold extend to Ψ∞ (M0 ).

    pdf32p noel_noel 17-01-2013 23 5   Download

  • Tham khảo luận văn - đề án 'research report: "the w - the germ of function defined on the manifold r-reticular"', luận văn - báo cáo phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả

    pdf7p phalinh14 07-08-2011 29 4   Download

  • Tuyển tập các báo cáo nghiên cứu khoa học ngành toán học được đăng trên tạp chí toán học quốc tế đề tài: Automated target tracking and recognition using coupled view and identity manifolds for shape representation

    pdf17p sting03 04-02-2012 22 4   Download

  • Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article A Metric Multidimensional Scaling-Based Nonlinear Manifold Learning Approach for Unsupervised Data Reduction

    pdf12p dauphong16 20-02-2012 23 4   Download

  • There are very few examples of Riemannian manifolds with positive sectional curvature known. In fact in dimensions above 24 all known examples are diffeomorphic to locally rank one symmetric spaces. We give a partial explanation of this phenomenon by showing that a positively curved, simply connected, compact manifold (M, g) is up to homotopy given by a rank one symmetric space, provided that its isometry group Iso(M, g) is large. More precisely we prove first that if dim(Iso(M, g)) ≥ 2 dim(M ) − 6, then M is tangentially homotopically equivalent to a rank one symmetric space or M...

    pdf63p noel_noel 17-01-2013 23 4   Download

  • Let M be a connected compact pseudoRiemannian manifold acted upon topologically transitively and isometrically by a connected noncompact simple Lie group G. If m0 , n0 are the dimensions of the maximal lightlike subspaces tangent to M and G, respectively, where G carries any bi-invariant metric, then we have n0 ≤ m0 . We study G-actions that satisfy the condition n0 = m0 .

    pdf30p noel_noel 17-01-2013 20 4   Download

  • Manifold-systems FIBRO Manifold-systems • could be used alternative to gas spring hose systems • is known for a very low pressure and force increase during the complete stroke length • high repair and service facilities by long maintenance rate • no hose systems necessary • guarantee of tightness also by numbers of assembling and disassembling of the system • small mounting dimensions • PED 97/23/EC approved and ready to be installed

    pdf4p nguyen8 03-12-2009 48 3   Download

  • Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Monocular 3D Tracking of Articulated Human Motion in Silhouette and Pose Manifolds

    pdf18p dauphong16 20-02-2012 21 3   Download

Đồng bộ tài khoản