Wavelet analysis of beam-soil structure response for fast moving train

This paper presents a wavelet based approach for the vibratory analysis of beam-soil structure related to a point load moving along a beam resting on the surface. The model is represented by the Euler-Bernoulli equation for the beam, elastodynamic equation of motion for the soil and appropriate boundary conditions. Two cases are analysed: the model with a half space under the beam and the model where the supporting medium has a finite thickness. Analytical solutions for the displacements are obtained and discussed in relation to the used boundary conditions and the type of considered loads: harmonic and constant. The analysis in time-frequency and velocity-frequency domains is carried out for realistic systems of parameters describing physical properties of the model. The approximate displacement values are determined by applying a wavelet method for a derivation of the inverse Fourier transform. A special form of the coiflet filter used in numerical calculations allows to carry out analysis without loss of accuracy related to singularities appearing in wavelet approximation formulas, when dealing with standard filters and complex dynamic systems. © 2009 IOP Publishing Ltd

In situ Characterisation of Practical Heterogeneous Catalysts

In situ methods are considered as a curiosity within the standard methodology of practical catalyst characterization. The methods are not commercially available and need to be adapted and validated for each specific problem. The great advantage of these methods is, however, that they deliver immediately relevant characteristics of the working state of a heterogeneous catalyst and allow justified structure-function relations to be deduced. To achieve this it is essential that the experiments are planned and conducted in such away that the proven to be active state of the catalyst is investigated. This can only be ascertained if simultaneous kinetic and spectroscopic data are acquired. The contribution lists a selection of methods with their main characteristics that allows to choose from the wide spectrum of information those that are most relevant for the given problem. A tabulated selection of case studies from the literature gives some insight in the current practice