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91.
92.
A mathematical model is presented for the determination of optimal mix of asbestos fibres to satisfy a set of desired pipe properties which vary with pipe size, class, and material availability. The approach utilizes a linear/separable programming model which is aimed at minimizing the total cost of fibres used. The fibre properties, such as reinforcing strength, processability, and length as well as cost and stocks available are taken into account in the model. Also represented are the profile of the ideal mix relative to the required composite strength, processability, and ‘dust content’. Asbestos mixes designed using the model have been implemented in the production of asbestos/cement pipes in one of the asbestos/cement pipe manufacturing plants in the Gulf area. Optimum model mixes have demonstrated significant technical and economic merits over the conventionally designed mixes. 相似文献
93.
94.
Nicolas Th. Varopoulos 《Milan Journal of Mathematics》2007,75(1):1-60
In this paper I consider a class of non-standard singular integrals motivated by potential theoretic and probabilistic considerations.
The probabilistic applications, which are by far the most interesting part of this circle of ideas, are only outlined in Section
1.5: They give the best approximation of the solution of the classical Dirichlet problem in a Lipschitz domain by the corresponding solution by finite differences.
The potential theoretic estimate needed for this gives rise to a natural duality between the L
p
functions on the boundary ∂Ω and a class of functions A on Ω that was first considered by Dahlberg. The actual duality is given by ∫Ω
S f(x)A(x)dx = (f, A) where S f(x) = ∫∂Ω |x − y|1−n
f(y)dy is the Newtonian potential.
We can identify the upper half Lipschitz space with in the obvious way and express for an appropriate kernel K. It is the boundedness properties of the above (for , ) that is the essential part of this work. This relates with more classical (but still “rough”) singular integrals that have
been considered by Christ and Journé.
Lecture held in the Seminario Matematico e Fisico on March 14, 2005
Received: April 2007 相似文献
95.
96.
The potential energy in materials is well approximated by pair functional which is composed of pair potentials and embedding
energy. During calculating material potential energy, the orientational component and the volumetric component are derived
respectively from pair potentials and embedding energy. The sum of energy of all these two kinds of components is the material
potential. No matter how microstructures change, damage or fracture, at the most level, they are all the changing and breaking
atomic bonds. As an abstract of atomic bonds, these components change their stiffness during damaging. Material constitutive
equations have been formulated by means of assembling all components’ response functions. This material model is called the
component assembling model. Theoretical analysis and numerical computing indicate that the proposed model has the capacity
of reproducing some results satisfactorily, with the advantages of great conceptual simplicity, physical explicitness, and
intrinsic induced anisotropy, etc.
Supported by the National Natural Science Foundation of China (Grant Nos. 10572140 and 10232050) and the Ministry of Science
and Technology Foundation (Grant No. 2002CB412706) 相似文献
97.
Anna Romanowska 《Algebra Universalis》2001,46(1-2):321-341
The paper shows that certain sums of algebras admit a representation as subdirect products. As a corollary, one obtains a
characterization of subdirectly irreducible algebras. Examples of modes show that the characterization gives a good basis
for a detailed investigation of the subdirectly irreducible algebras.
Received September 10, 1999; accepted in final form January 3, 2001. 相似文献
98.
Stefan M. Stefanov 《Computational Optimization and Applications》2001,18(1):27-48
A minimization problem with convex and separable objective function subject to a separable convex inequality constraint and bounded variables is considered. A necessary and sufficient condition is proved for a feasible solution to be an optimal solution to this problem. Convex minimization problems subject to linear equality/linear inequality constraint, and bounds on the variables are also considered. A necessary and sufficient condition and a sufficient condition, respectively, are proved for a feasible solution to be an optimal solution to these two problems. Algorithms of polynomial complexity for solving the three problems are suggested and their convergence is proved. Some important forms of convex functions and computational results are given in the Appendix. 相似文献
99.
We prove equivalence of the definitions by the author and by Korevaar and Schoen of the Sobolev classes of mappings of a domain of an arithmetic n-dimensional space to a metric space. 相似文献
100.
We study smoothing properties for time-dependent Schrödinger equations , , with potentials which satisfy V(x)=O(|x|m) at infinity, m?2. We show that the solution u(t,x) is 1/m times differentiable with respect to x at almost all , and explain that this is the result of the fact that the sojourn time of classical particles with energy λ in arbitrary compact set is less than CTλ−1/m during [0,T] when λ is very large. We also show Strichartz's inequality with derivative loss for such potentials and give its application to nonlinear Schrödinger equations. 相似文献