A fully automatic method for predicting internal reacting flows

A fully automatic method for computing elliptic internal reacting flows is presented. It uses a majorant operator-splitting method for the conservation of species equations, which permits their usually problematic integration to be performed in a two-step process. For the first nonreacting stage the algorithm of Gosman et al. [18] is utilised, whilst the form of the second reacting stage enables the method of characteristics to be implemented so that a set of ordinary differential equations is obtained. The latter are solved using Gear's [5] method for combatting the stiffness that is frequently associated with problems involving realistic chemical kinetic schemes. Some sample results for turbulent reacting flow in a combustor with a conical burner tunnel section demonstrate the viability of the technique.     

On a conjecture of Bredon

Using the localization technique for equivariant cohomology theory we prove a conjecture of G.Bredon (s. [4], p.381) which states that under certain conditions (s. the theorem below) the cohomology with Z_p-coefficients of each component of the fixpoint set of a Z_p-space can be generated as an algebra by (at most) the same number of elements as the cohomology of the space itself.     

Deformations of algebras and cohomology of fixed point sets

In [13] it is shown that under certain conditions the cohomology algebra of the fixed point set of a space with group action is in an algebraic sense a deformation of the cohomology algebra of the space itself. Here we attempt to prove a converse of the above statement, i.e. we try to realize geometrically a given algebraic deformation of a (commutative) graded algebras as the cohomology algebra of the fixed point set of a suitable space with group action. The first part of this note in a sense reduces this realization problem in equivariant topology to a non-equivariant problem while the second part uses Sullivan's theory of minimal models to actually obtain a converse for S¹-actions, where cohomology is taken with rational coefficients.     

Observation of two-electron-one-photon transitions in silicon

We report on the observation of Kαα X-rays of Si, produced in collisions of 15–28 MeV Si projectiles with various target atoms in the range Z = 6 to 29. Energy shifts of X-rays were measured and are compared with theoretical predictions. Cross section ratios for emission of Kαα and Kα radiation are given.