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- Byström, Johan, et al.
(författare)
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A numerical study of the convergence in stochastic homogenization
- 2004
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Ingår i: Journal of Analysis and Applications. - 0972-5954. ; 2:3, s. 159-171
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Tidskriftsartikel (refereegranskat)abstract
- This note makes the link between theoretical results on stochastic homogenization and effective computation of averaged coefficients for diffusion operators in random media. Examples of how to construct relevant random media and numerical results on the effective coefficients are given.
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- Byström, Johan, et al.
(författare)
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An evaluation of different models for prediction of elastic properties of woven composites
- 2000
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Ingår i: Composites Part B. - 1359-8368 .- 1879-1069. ; 31:1, s. 7-20
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Tidskriftsartikel (refereegranskat)abstract
- A critical analysis of two simple and convenient analytical models for calculation of elastic properties of woven fabric composites is performed. Predictions of these models are compared with results obtained using the method of reiterated homogenization and with experimental data for plain weave glass fiber and carbon fiber polyester composites. Three different scales are identified in the analysis. The first scale predictions, which are the tow properties (obtained by applying Hashin's concentric cylinder model, the Halpin-Tsai expressions or mathematical homogenization technique), are the most critical because they form the input information for woven composite modeling. It appears that the uncertainty in this information causes larger differences in predictions than the deviations between models of different degree of accuracy. This fact sets limits on the required accuracy of the models. Model comparisons reveal that the woven compoiste model based on isostrain assumption in the compoiste plane and isostress assumption for out-of-plane components is in very good agreement with both experimental data and the reiterated homogenization method, whereas the modified mosaic parallel model fails to describe composites with large interlaced regions.
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- Byström, Johan, et al.
(författare)
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Bounds and numerical results for the homogenized degenerated p-Poisson equation
- 2004
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Ingår i: Applications of Mathematics. - 0862-7940 .- 1572-9109. ; 49:2, s. 111-122
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we derive upper and lower bounds on the homogenized energy density functional corresponding to degenerated p-Poisson equations. Moreover, we give some non-trivial examples where the bounds are tight and thus can be used as good approximations of the homogenized properties. We even present some cases where the bounds coincide and also compare them with some numerical results.
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- Byström, Johan
(författare)
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Correctors for some nonlinear monotone operators
- 2001
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Ingår i: Journal of Nonlinear Mathematical Physics. - : Springer Science and Business Media LLC. - 1402-9251 .- 1776-0852. ; 8:1, s. 8-30
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we study homogenization of quasi-linear partial differential equations of the form -div (a (x, x/εh,Duh)) = fh on Ω with Dirichlet boundary conditions. Here the sequence (εh) tends to 0 as h→∞ and the map a (x, y, ξ) is periodic in y, monotone in ξ and satisfies suitable continuity conditions.W e prove that uh → u weakly in W1,p 0 (Ω) as h → ∞, where u is the solution of a homogenized problem of the form -div (b (x,Du)) = f on Ω. We also derive an explicit expression for the homogenized operator b and prove some corrector results, i.e. we find (Ph) such that Duh -Ph (Du) → 0 in Lp (Ω,Rn). () 0 in (Ω).
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- Byström, Johan, et al.
(författare)
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Cross section dependence on ski pole stiffness
- 2013
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Rapport (refereegranskat)abstract
- Ski equipment producer SWIX has recently presented a new pair of ski poles,called SWIX Triac, which di¤ers from conventional (round) ski poles by having atriangular cross section. SWIX claims that the main objective for this design is thatit has superior sti¤ness to weight ratio compared to common ski poles. We provein this paper that this claim in general is not true. More speci…c, we show thatfor thin walled cross sections, a hollow circular cross section has up to 36% bettersti¤ness to weight ratio than a corresponding triangular cross section.
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