On intersections of conjugate subgroups

We define a new invariant of a conjugacy class of subgroups which we call the breadth and prove that a quasiconvex subgroup of a negatively curved group has finite breadth in the ambient group. Utilizing the coset graph and the geodesic core of a subgroup we give an explicit algorithm for constructing a finite generating set for an intersection of a quasiconvex subgroup of a negatively curved group with its conjugate. Using that algorithm we construct algorithms for computing the breadth, the width, and the height of a quasiconvex subgroup of a negatively curved group. These algorithms decide if a quasiconvex subgroup of a negatively curved group is almost malnormal in the ambient group. We also explicitly compute a quasiconvexity constant of the intersection of two quasiconvex subgroups and give examples demonstrating that height, width, and breadth are different invariants of a subgroup.

An Invariant Analysis of the Bending of Three Edge-Bonded Dissimilar Plates

A representation theorem is proved for the solution of the problem of two perfectly bonded isotropic semi-infinite plates under the influence of an arbitrary vertical load located in the midplane of the interior of one of them. Its function is to show that if the deflection of an unbounded isotropic plate under the influence of an arbitrary vertical load is known, then the corresponding deflections for two perfectly bonded isotropic semi-infinite plates are explicitly determinable, solely, and compactly in terms of the known deflection. Indeed, whatever the nature of the mechanism of loading is, the induced bending moments and shears in the two bonded plates are determinable by the process of differentiation only. A systematic repeated application of the theorem then yields a well-structured series solution when the arbitrary vertical load is arbitrarily located in a compound plate comprising two semi-infinite dissimilar isotropic plates separated by another dissimilar isotropic plate strip of finite breadth. As an application, we determine the effective elastic constants of a compound plate comprising a homogeneous isotropic plate in which a finite number of isotropic parallel plate strips of small breadths are embedded at such distances apart that their interaction effects may be taken as independent of one another.

Implementation of a Cavitation Algorithm into a Procedure for the Prediction of Non-Newtonian Flow in Hydrodynamic Journal Bearings

A procedure for solving the Navier–Stokes equations for the steady, three-dimensional, cavitated flow of non-Newtonian liquids within finite-breadth journal bearings is described. The method uses a finite difference approach, together with a technique known as SIMPLE (Semi-Implicit Method for Pressure-Linked Equations) which has now become well established in the field of computational fluid dynamics. The concept of ‘effective viscosity’ to describe the non-linear dependence of shear stress on shear rate is used to predict the performance of bearings having a single axial inlet groove situated at the position of maximum clearance between the shaft and housing. The implementation of a cavitation algorithm into the equation set allows the loci of film rupture and reformation in the vicinity of the supply groove and elsewhere to be traced, these having a particularly important influence on the predicted lubricant flowrate. Results are obtained for a range of non-linearity factors and lead to the conclusion that all the important indicators of bearing performance can be determined using the technique described.