The performance characteristics of sliced lung sets were compared to lung sets with activity homogeneously distributed throughout the lung tissue substitute material. The activity estimate from planar sources differs from the estimate from homogeneous sources by a factor of 0.88 to 1.09 depending on the photon energy. This error is small compared to other uncertainties commonly encountered in l...

We report experiments on piles of cohesionless granular materials showing the effect of construction history on static stress distributions. Stresses under piles are monitored by sensitive capacitive techniques. The piles are formed either by pouring granular material from a funnel with a small outlet (localized source), or from a large sieve (homogeneous rain). Localized sources yield stress p...

A numerical method for extracting the coef®cients of the asymptotic series solution of the Poisson equation in two dimensions in the vicinity of singular points is presented. This method is an extension of that presented in (Szabo and Yosibash 1996) to non-homogeneous boundary value problems, and is general in the sense that it is applicable to almost any type of point singularity. Numerical e...

We investigate a two-phase porous media flow model, in which dynamic effects are taken into account in phase pressure difference. We consider a one-dimensional heterogeneous case, with two adjacent homogeneous blocks separated by an interface. The absolute permeability is assumed constant, but different in each block. This may lead to the entrapment of the nonwetting phase (say, oil) when flowi...

The aim of the present study was to predict damage to masonry by combining structural analysis and homogenization methods. In the case of a masonry structure composed of bricks and mortar, a third material is assumed to exist, which is a mixture of the two materials sandwiched between the other two. This new layer has a small thickness, a low stiffness and a given damage ratio. The mechanical p...

Motivated by recent best case analyses for some sorting algorithms and based on the type of complexity we partition the algorithms into two classes: homogeneous and non-homogeneous algorithms.1 Although both classes contain algorithms with worst and best cases, homogeneous algorithms behave uniformly on all instances. This partition clarifies in a completely mathematical way the previously ment...

Unless otherwise noted, we consider only n > 0. The parameters in (1.1) are all integers satisfying k, pi and aij > 0. Assume c initial conditions R(1) = ξ1, R(2) = ξ2, . . . , R(c) = ξc, with all ξi > 0. Golomb [6] first solved the simplest example of such a non-homogeneous nested recursion, namely, G(n) = G(n− G(n− 1)) + 1, G(1) = 1; see also [7]. In fact, all of the recursions we find with c...

used for staining with fluorescent antibodies. After a period of 12 hours the stain revealed a diffuse fluorescence that occupied the nucleus except for areas correspond ing to the nucleoli. The stained nuclei increased in number during the subsequent 16, 20, and 2-1hours corresponding to the log phase of viral growth. On the 2d day after inoculation, when the viral growth curve had reached a p...

Abstract. We study the reconstruction of a 3D compact homogeneous object lying inside a homogeneous background for computer aided design (CAD) or nondestructive testing (NDT) applications. Such a binary scene describes either a solid object or an homogeneous material in which a fault is sought. The goal in both cases is to reconstruct the shape of the scene from sparse radiographic data. This p...