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991.
M.E. Petty 《Topology and its Applications》1982,14(1):71-85
Let R+ be the space of nonnegative real numbers. F. Waldhausen defines a k-fold end structure on a space X as an ordered k-tuple of continuous maps xf:X → R+, 1 ? j ? k, yielding a proper map x:X → (R+)k. The pairs (X,x) are made into the category Ek of spaces with k-fold end structure. Attachments and expansions in Ek are defined by induction on k, where elementary attachments and expansions in E0 have their usual meaning. The category Ek/Z consists of objects (X, i) where i: Z → X is an inclusion in Ek with an attachment of i(Z) to X, and the category Ek6Z consists of pairs (X,i) of Ek/Z that admit retractions X → Z. An infinite complex over Z is a sequence X = {X1 ? X2 ? … ? Xn …} of inclusions in Ek6Z. The abelian grou p S0(Z) is then defined as the set of equivalence classes of infinite complexes dominated by finite ones, where the equivalence relation is generated by homotopy equivalence and finite attachment; and the abelian group S1(Z) is defined as the set of equivalence classes of X1, where X ∈ Ek/Z deformation retracts to Z. The group operations are gluing over Z. This paper presents the Waldhausen theory with some additions and in particular the proof of Waldhausen's proposition that there exists a natural exact sequence 0 → S1(Z × R)→πS0(Z) by utilizing methods of L.C. Siebenmann. Waldhausen developed this theory while seeking to prove the topological invariance of Whitehead torsion; however, the end structures also have application in studying the splitting of a noncompact manifold as a product with R[1]. 相似文献
992.
Jutta Mitas 《Order》1991,8(2):115-132
Although the jump number problem for partially ordered sets in NP-complete in general, there are some special classes of posets for which polynomial time algorithms are known.Here we prove that for the class of interval orders the problem remains NP-complete. Moreover we describe another 3/2-approximation algrithm (two others have been developed already by Felsner and Syslo, respectively) by using a polynomial time subgraph packing algorithm. 相似文献
993.
Yisong Yang 《Letters in Mathematical Physics》1990,20(4):285-290
The existence of self-dual or anti-self-dual monopoles of a seven-dimensional generalized Yang-Mills-Higgs theory is proved using the second-order equations of motion. The behavior of solutions can be used to recognize self- or anti-self-duality. Moreover, it is shown that, in the class of the field configurations under discussion, the solutions are, in fact, unique. 相似文献
994.
用PHI 600型扫描俄歇探针、200型台阶仪和Q-920型图象分析仪,测定了35Cr Ni3MoV钢、Al-5.5 Zn-1.4Mg合金和Ti-5Al-2.5Sn合金的溅射速率,提出了对蚀坑分部位确定溅射速率的方法。文中给出了详细的测定结果。 相似文献
995.
996.
We classify the holomorphic diffeomorphisms
of complex projective varieties with an Anosov dynamics and
holomorphic stable and unstable foliations: The variety is
finitely covered by a compact complex torus and the diffeomorphism
corresponds to a linear transformation of this torus.
Difféomorphismes holomorphes Anosov相似文献
997.
We deal with compact Kähler manifolds M acted on by a compact Lie group K of isometries, whose complexification K has exactly one open and one closed orbit in M. If the K-action is Hamiltonian, we investigate topological and cohomological properties of M. 相似文献
998.
M Ghomi 《Topology》2004,43(1):245
Solomon (Projecting codimension-two cycles to zero on hyperplanes in , Topology (2004) X-ref: doi:10.1016/S0040-9383(03)00043-0) has studied the problem of existence of a simple closed curve in whose projections into planes in three linearly independent directions vanish in the sense of currents. He discovered some nonsmooth examples of such curves, and proved that no examples (smooth or otherwise) exist on strictly convex surfaces. We show that smooth (C∞) examples exist, and may be constructed on convex surfaces. 相似文献
999.
Ngamta Thamwattana Grant M. Cox James M. Hill 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2004,55(2):330-356
The practice of storing granular materials in stock
piles occurs throughout the world in many industrial situations.
As a result, there is much interest in predicting the stress
distribution within a stock pile. In 1981, it was suggested from
experimental work that the peak force at the base does not occur
directly beneath the vertex of the pile, but at some intermediate
point resulting in a ring of maximum pressure. With this in mind,
any analytical solution pertaining to this problem has the
potential to provide useful insight into this phenomenon. Here, we
propose to utilize some recently determined exact parametric
solutions of the governing equations for the continuum mechanical
theory of granular materials for two and three-dimensional stock
piles. These solutions are valid provided sin = 1, where
is the angle of internal friction, and we term such
materials as highly frictional. We note that there exists
materials possessing angles of internal friction around 60 to 65
degrees, resulting in values of sin equal to around 0.87 to
0.91. Further, the exact solutions presented here are potentially
the leading terms in a perturbation solution for granular
materials for which 1- sin is close to zero. The model
assumes that the stock pile is composed of two regions, namely an
inner rigid region and an outer yield region. The exact parametric
solution is applied to the outer yield region, and the solution is
extended continuously into the inner rigid region. The results
presented here extend previous work of the authors to the case of
highly frictional granular solids. 相似文献
1000.
Chein-Shan?LiuEmail author 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2004,55(4):606-625
In this paper we present a linear representation of the
Landau-Lifshitz-Gilbert equation for describing the magnetization
of ferromagnetic materials. According to Lies theory, we prove
that this equation admits a superposition principle and its
formula is derived. The underlying vector space of the
Landau-Lifshitz-Gilbert equation is found to be a projective
Minkowski space denoted by
of which the
projective proper orthochronous Lorentz group
PSO
o(3,1)
left acts. By the Lie symmetry a group preserving scheme is developed,
which improves the computational accuracy and efficiency. 相似文献