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1.
The aim of this paper is to present two different approachs in order to obtain an existence result to the so-called quadrature
surface free boundary problem. The first one requires the shape derivative calculus while the second one depends strongly
on the compatibility condition of the Neumann problem. A necessary and sufficient condition of existences is given in the
radial case. 相似文献
2.
3.
Two polyester-based polymer concretes with various volume content of diabase as an extender and aggregate are tested in creep
under compression at different stress levels. The phenomenological and structural approaches are both used to analyze the
experimental data. Common features of changes in the instantaneous and creep compliances are clarified, and a phenomenological
creep model which accounts for the changes in the instantaneous compliance and in the retardation spectrum depending on the
stress level is developed. It is shown that the model can be used to describe the experimental results of stress relaxation
and creep under repeated loading. Modeling of the composite structure and subsequent solution of the optimization problem
confirm the possibility of the existence of an interphase layer more compliant than the binder. A direct correlation between
the interphase volume content and the instantaneous compliance of the composite is revealed. It is found that the distinction
in nonlinearity of the viscoelastic behavior of the two polymer concretes under investigation can be due to the difference
in their porosity.
Submitted to the 11th International Conference on Mechanics of Composite Materials (Riga, June 11–15, 2000.)
Translated from Mekhanika Kompozitnykh Materialov, Vol. 36, No. 2, pp. 147–164, 2000. 相似文献
4.
V. P. Stavrov V. V. Stavrov N. V. Pankova K. Friedrich 《Mechanics of Composite Materials》2000,36(2):155-162
The influence of displacements of tensioned fibers on the impregnation of fibrous layers with a polymer melt and on the final
composite structure is studied. Using computer simulation, it is shown that, during impregnation, the structure of tensioned
fibrous layers changes considerably depending on the initial arrangement and tensioning of fibers. The consolidated regions
formed under the melt front move inside the impregnated layer with the advancing melt front. Displacement of the tensioned
fibers as well as the formation of “washouts” favors the impregnation of internal layers, but cause significant inhomogeneity
of the polymer structure. The surface (on the side of the melt flow) regions are more saturated with the polymer than the
internal ones. A difference in the melt percolation mechanisms at various impregnation regimes is revealed. The effective
permeability coefficients of a tensioned fiber layer are not constant but depend on the conditions and regimes of impregnation.
Submitted to the 11th Conference on the Mechanics of Composite Materials (Riga, June 11–15, 2000).
Translated from Mekhanika Kompozitnykh Materialov, Vol. 36, No. 2, pp. 259–270, March–April, 2000. 相似文献
5.
A. A. Okhlopkova A. V. Vinogradov C. A. Sleptsova G. N. Alexandrov 《Mechanics of Composite Materials》1999,35(6):521-526
Composite polymer materials based on PTFE containing ultradisperse -sialon (1–10 wt.%) as the cross-linking agent are studied. It is shown that the injection of small amounts of fillers (1–2 wt.%) increases the degree of composite crystallinity. A correlation between the structure, element distribution on the surface layers of samples, and tribotechnical characteristics of composites is found. The change in the physicomechanical characteristics is associated with the effect of the interstructural plasticization.Ammosov Yakutsk State University, Yakutsk, Russia. Translated from Mekhanika Kompozitnykh Materialov, Vol. 35, No. 6, pp. 797–806, November–December, 1999. 相似文献
6.
Agata Smoktunowicz 《Central European Journal of Mathematics》2005,3(4):644-653
Let F be a field, and let R be a finitely-generated F-algebra, which is a domain with quadratic growth. It is shown that either the center of R is a finitely-generated F-algebra or R satisfies a polynomial identity (is PI) or else R is algebraic over F. Let r ∈ R be not algebraic over F and let C be the centralizer of r. It is shown that either the quotient ring of C is a finitely-generated division algebra of Gelfand-Kirillov dimension 1 or R is PI. 相似文献
7.
A number of explicit solutions for the heat equation with a polynomial non-linearity and for the Fisher equation is presented.
An extended class of non-linear heat equations admitting solitary wave solutions is described. The generalization of the Fisher
equation is proposed whose solutions propagate with arbitrary ad hoc fixed velocity. 相似文献
8.
Laurenťiu Leuštean 《Central European Journal of Mathematics》2003,1(3):382-397
In this paper we study the prime and maximal spectra of a BL-algebra, proving that the prime spectrum is a compact T
0 topological space and that the maximal spectrum is a compact Hausdorff topological space. We also define and study the reticulation
of a BL-algebra. 相似文献
9.
Alexander N. Rudy 《Central European Journal of Mathematics》2005,3(4):606-613
The paper deals with the real classical Lie algebras and their finite dimensional irreducible representations. Signature formulae
for Hermitian forms invariant relative to these representations are considered. It is possible to associate with the irreducible
representation a Hurwitz matrix of special kind. So the calculation of the signatures is reduced to the calculation of Hurwitz
determinants. Hence it is possible to use the Routh algorithm for the calculation. 相似文献
10.
This paper is aimed at studying negatively curved Riemannian manifolds acted on by a Lie group of isometries with principal orbits of codimension one. The orbit space of such a manifold M is proved to be always homeomorphic to or + and this second case may occur only when either the singular orbit is a geodesic of M or when the space is simply connected. Several corollaries are given. 相似文献
11.
We present diagrammatic schemes characterizing congruence 3-permutable and distributive algebras. We show that a congruence
3-permutable algebra is congruence meetsemidistributive if and only if it is distributive. We characterize varieties of algebras
satisfying the so-called triangular scheme by means of a Maltsev-type condition. 相似文献
12.
Evald Übi 《Central European Journal of Mathematics》2005,3(2):228-241
A linear programming problem is transformed to the finding an element of polyhedron with the minimal norm. According to A.
Cline [6], the problem is equivalent to the least squares problem on positive ortant. An orthogonal method for solving the
problem is used. This method was presented earlier by the author and it is based on the highly developed least squares technique.
First of all, the method is meant for solving unstable and degenerate problems. A new version of the artifical basis method
(M-method) is presented. Also, the solving of linear inequality systems is considered. 相似文献
13.
Manuel Abad Cecilia Cimadamore José Patricio Díaz Varela Laura Rueda Ana María Suardíaz 《Central European Journal of Mathematics》2005,3(2):215-227
In this paper, the variety of closure n-valued Łukasiewicz algebras, that is, Łukasiewicz algebras of order n endowed with a closure operator, is investigated. The lattice of subvarieties in the particular case in which the open elements
form a three-valued Heyting algebra is obtained. 相似文献
14.
Two differential operators which act on holomorphic mappings to complex projective space are studied. One operator is of second order and characterizes projective linear mappings. The other operator is of third order and may be viewed as a curvature. The two operators together play a role analogous to the Schwarzian derivative.A canonical approximation to a holomorphic mapping is defined, and a relationship between the approximation and the operators is derived. In the one variable case, this reduces to a classical result relating the Schwarzian derivative and the best Möbius approximation to a holomorphic function. 相似文献
15.
Maksim Sokolov 《Central European Journal of Mathematics》2005,3(4):627-643
In the current work a generalization of the famous Weyl-Kodaira inversion formulas for the case of self-adjoint differential
vector-operators is proved. A formula for spectral resolutions over an analytical defining set of solutions is discussed.
The article is the first part of the planned two-part survey on the structural spectral theory of self-adjoint differential
vector-operators in matrix Hilbert spaces.
The work is dedicated to Professor Ravshan Ashurov on occasion of his 50-th anniversary. 相似文献
16.
Joanna Janczewska 《Central European Journal of Mathematics》2004,2(4):561-572
In this work we study the problem of the existence of bifurcation in the solution set of the equation F(x, λ)=0, where F: X×R
k
→Y is a C
2-smooth operator, X and Y are Banach spaces such that X⊂Y. Moreover, there is given a scalar product 〈·,·〉: Y×Y→R
1 that is continuous with respect to the norms in X and Y. We show that under some conditions there is bifurcation at a point (0, λ0)∈X×R
k
and we describe the solution set of the studied equation in a small neighbourhood of this point. 相似文献
17.
The Evens-Lu-Weinstein representation (Q
A
, D) for a Lie algebroid A on a manifold M is studied in the transitive case. To consider at the same time non-oriented manifolds as well, this representation is slightly
modified to (Q
A
or
, Dor) by tensoring by orientation flat line bundle, Q
A
or
=QA⊗or (M) and D
or=D⊗∂
A
or
. It is shown that the induced cohomology pairing is nondegenerate and that the representation (Q
A
or
, Dor) is the unique (up to isomorphy) line representation for which the top group of compactly supported cohomology is nontrivial.
In the case of trivial Lie algebroid A=TM the theorem reduce to the following: the orientation flat bundle (or (M), ∂
A
or
) is the unique (up to isomorphy) flat line bundle (ξ, ∇) for which the twisted de Rham complex of compactly supported differential
forms on M with values in ξ possesses the nontrivial cohomology group in the top dimension. Finally it is obtained the characterization
of transitive Lie algebroids for which the Lie algebroid cohomology with trivial coefficients (or with coefficients in the
orientation flat line bundle) gives Poincaré duality. In proofs of these theorems for Lie algebroids it is used the Hochschild-Serre
spectral sequence and it is shown the general fact concerning pairings between graded filtered differential ℝ-vector spaces:
assuming that the second terms live in the finite rectangular, nondegeneration of the pairing for the second terms (which
can be infinite dimensional) implies the same for cohomology spaces. 相似文献
18.
Cartan matrices of selfinjective algebras of tubular type 总被引:1,自引:0,他引:1
Jerzy Białkowski 《Central European Journal of Mathematics》2004,2(1):123-142
The Cartan matrix of a finite dimensional algebra A is an important combinatorial invariant reflecting frequently structural properties of the algebra and its module category.
For example, one of the important features of the modular representation theory of finite groups is the nonsingularity of
Cartan matrices of the associated group algebras (Brauer’s theorem). Recently, the class of all tame selfinjective algebras
having simply connected Galois coverings and the stable Auslander-Reiten quiver consisting only of stable tubes has been shown
to be the class of selfinjective algebras of tubular type, that is, the orbit algebras
/G of the repetitive algebras
of tubular algebras B with respect to the actions of admissible groups G of automorphisms of
. The aim of the paper is to describe the determinants of the Cartan matrices of selfinjective algebras of tubular type and
derive some consequences. 相似文献
19.
Rafał Bocian Thorsten Holm Andrzej Skowroński 《Central European Journal of Mathematics》2004,2(1):67-75
Auslander’s representation dimension measures how far a finite dimensional algebra is away from being of finite representation
type. In [1], M. Auslander proved that a finite dimensional algebra A is of finite representation type if and only if the representation dimension of A is at most 2. Recently, R. Rouquier proved that there are finite dimensional algebras of an arbitrarily large finite representation
dimension. One of the exciting open problems is to show that all finite dimensional algebras of tame representation type have
representation dimension at most 3. We prove that this is true for all domestic weakly symmetric algebras over algebraically
closed fields having simply connected Galois coverings. 相似文献
20.
J. Szenthe 《Central European Journal of Mathematics》2004,2(5):725-731
Spherically symmetric space-times have attained considerable attention ever since the early beginnings of the theory of general
relativity. In fact, they have appeared already in the papers of K. Schwarzschild [12] and W. De Sitter [5] which were published
in 1916 and 1917 respectively soon after Einstein's epoch-making work [7] in 1915. The present survey is concerned mainly
with recent results pertainig to the toplogy of spherically symmetric space-times.
Definition. By space-time a connected time-oriented 4-dimensional Lorentz manifold is meant. If (M,<,>) is a space-time, and Φ: SO(3)×M→M an isometric action such that the maximal dimension of its orbits is equal to 2, then the action Φ is said to be spherical and the space-time is said to be spherically symmetric [8]; [11]. Likewise, isometric actions Ψ: O(3)×M→M are also considered ([10], p. 365; [4]) which will be called quasi-spherical if the maximal dimension of its orbits is 2 and then the space-time is said to be quasi-spherically symmetric here. Each quasi-spherical action yields a spherical one by restricting it to the action of SO(3); the converse of this statement will be considered elsewhere.
The main results concerning spherically symmetric space-times are generally either of local character or pertaining to topologically
restricted simple situations [14], and earlier results of global character are scarce [1], [4], [6], [13]. A report on recent
results concerning the global geometry of spherically symmetric space-times [16] is presented below. 相似文献