Essent (Netherlands)

The forced oscillations of the damping mechanical system of solids "Ball Vibration Absorber (BVA) with linearly viscous resistancea movable carrier body" under the influence of external harmonic excitation are considered. Based on Appell's formalism, the dynamic equations for the joint motion of a heavy ball without sliding into a spherical cavity of a carrier body are formulated and numerically studied. The amplitude-frequency characteristic of the damping mechanical system and the curves of the dependences of the maximum amplitude of the oscillations of the carrier body on the values of the radius of the spherical cavity and the coefficient of viscous resistance of the BVA are obtained. The conditions and restrictions on the rolling of a heavy ball in the spherical recess of the absorber without sliding are determined.

This paper evaluates the Pugh Controlled Convergence method and its relationship to recent developments in design theory. Computer executable models are proposed simulating a team of people involved in iterated cycles of evaluation, ideation, and investigation. The models suggest that: (1) convergence of the set of design concepts is facilitated by the selection of a strong datum concept; (2) iterated use of an evaluation matrix can facilitate convergence of expert opinion, especially if used to plan investigations conducted between matrix runs; and (3) ideation stimulated by the Pugh matrices can provide large benefits both by improving the set of alternatives and by facilitating convergence. As a basis of comparison, alternatives to Pugh’s methods were assessed such as using a single summary criterion or using a Borda count. These models suggest that Pugh’s method, under a substantial range of assumptions, results in better design outcomes than those from these alternative procedures.

In the Netherlands, the safety of the gas distribution system is a hot issue. The public perception is that the safety of the system is decreasing, whilst the industry thinks that it is business as usual and that neither the number of incidents nor the consequences of incidents are larger than they used to be. Which of the claims is true? To this question there is no objective answer. First of all, no accessible database exists that contains records of all relevant incidents. Secondly, there is no agreed upon method to combine all those incidents into a simple, easy to understand indicator of safety. In this paper we first explore the theoretical framework for such an indicator. Combining this framework with actual incident data will result in a quantitative model. Finally, we present the results of the quantitative model. The paper ends with an outlook for the application of the indicator in the quality regulation of the Dutch gas distribution companies.