External damping losses in measuring the vibration damping properties in lightly damped specimens using transient time-domain methods

The contaminating effect of external damping sources to the overall measured damping of mechanical structures has always been an issue. Although these sources are qualitatively known, they are often not considered if damping properties are experimentally determined, yielding erroneous results. The aim of this paper is to quantify some of these undesired effects on the overall measured damping value. Free vibrations of steel plate specimens are used to list up several causes of external damping sources. As small modifications to the test setup may lead to totally different results, appropriate actions are offered to design a more accurate test setup. Known observations, such as the damping value’s dependence on the specimen size and the excitation level, are confirmed. Finally, it is shown that the damping capacity of one type of steel alloy can usually not be generalised to other steel alloys.     

A model to estimate the size of aggregates formed in a Dissolved Air Flotation unit

In Dissolved Air Flotation (DAF) a solid phase is separated from a liquid phase with the aid of air bubbles. The solid phase is usually coagulated into larger particles termed flocs. The air bubbles and flocs form aggregates, which rise to the surface of the flotation unit where they are removed. In this paper we propose a model that estimates the size of the formed aggregates. The estimation is based on the local balance of forces describing the approach and attachment of flocs to air bubbles. The interaction of flocs and bubbles is described by surface forces, hydrodynamic forces and the buoyancy force. The model is validated with available experimental results and the obtained aggregate sizes agree reasonable with those obtained by the experiments. The approach proposed here is intended for water treatment applications, but can be modified for other flotation processes.     

Goodness-of-fit tests based on a robust measure of skewness

In this paper we propose several goodness-of-fit tests based on robust measures of skewness and tail weight. They can be seen as generalisations of the Jarque–Bera test (Bera and Jarque in Econ Lett 7:313–318, 1981) based on the classical skewness and kurtosis, and as an alternative to the approach of Moors et al. (Stat Neerl 50:417–430, 1996) using quantiles. The power values and the robustness properties of the different tests are investigated by means of simulations and applications on real data. We conclude that MC-LR, one of our proposed tests, shows the best overall power and that it is moderately influenced by outlying values.     

Abstracts to Forthcoming Papers

Abstract

The determination of metal species in solutions is important to evaluate their biological activity in natural ecosystems. The practical possibilities of different analytical techniques to determine and speciate metals in soil systems are discussed. Separative techniques such as ion exchange chromatography and gelpermeation chromatography allow a species estimation based on charge characteristics or molecular size of water soluble metal compounds. Electrochemical techniques such as potentiometry with ion-selective electrodes and polarography provide more detailed information about complex formation and stability.     

Age-Related Carbonylation of Fibrocartilage Structural Proteins Drives Tissue Degenerative Modification

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Palladium‐Catalyzed Carbonylative α‐Arylation to β‐Ketonitriles

A carbonylative α‐arylation process employing unactivated nitriles for the first time is described. The reaction tolerates a range of (hetero)aryl iodides and several nitrile coupling partners. No prefunctionalization of the nitriles is necessary and the resulting β‐ketonitriles are obtained in good to excellent yields. The methodology also allows for a convenient ¹³C‐labelling of the generated carbonyl moiety.