Calculation of wear (f.i. wear modulus) in the plastic cup of a hip joint prosthesis

The wear equation is applied to the wear process in a hip joint prosthesis and a wear modulus is defined. The sliding distance, wear modulus, wear volume, wear area, contact angle and the maximum normal stress were calculated and the theoretical calculations applied to test results.\ud \ud During the wear process the increase of the wear modulus is about 100 Nmm−2 per mm sliding distance in the Charnley and the Charnley-Muller hip joint prosthesis. From the wear volume point of view the Charnley prosthesis is probably superior to the Charnley-Muller prosthesis if run-in before implantation

Internal dynamics around static-deformation FEM states

Constant velocity or constant force FEM solutions are static-deformation states, where the elastic deformation is stationary. These are the typical operation conditions. Time-dependence, or fluctuations, of the static-deformation states are treated as perturbations, leading to a fast-converging expansion, for typical operation conditions, in which the time-scale of the input force is slower than the internal dynamics

Functional system dynamics

This thesis addresses the question how continuous components can be analyzed and described such that the resulting model can be used in a larger system for system\ud analysis and simulation. The question focusses very much on the treatment of a single component and its means to interact with its surroundings. The interaction\ud takes the form of the power variables of bond-graph modelling representing the action-reaction pair which product is the energy ow in and out of the system

Three particle states and t-exchanges

The multiple particle final states in modern data from $4 \pi$ detector experiments offer a wealth of information about higher hadronic resonances and hadron interactions. However, it requires careful analysis to extract model independent results from those data.Comment: 4 pages, 1 figure, Proceedings of Nstar, Pittsburgh, Oct. 200

Coherent bubble-sum approximation for coupled-channel resonance scattering

For coupled-channel resonance scattering we derive a model with a closed form solution for the $T$-matrix that satisfies unitarity and analyticity. The two-channel case is handled explicitly for an arbitrary number of resonances. The method focuses on the expansion of the transition matrix elements, $\Gamma(s)$, in known analytical functions. The appropriate hadronic form factors and the related energy shifts can be determined from the scattering data. The differences between this method and the $K$-matrix and the Breit-Wigner approximation are illustrated in the case of the $S_{11}$ resonances $S_{11}(1535)$ and $S_{11}(1650)$.Comment: 8 pages, 1 figure, code available from http://www.phyast.pitt.edu/~norbertl/bubblegum2