Open Access

In den letzten Jahrzehnten kam es in Einzelfällen zu schweren Schäden an wasserbaulichen geotextilen Filteranlagen infolge der Verstopfung durch ausgeflockte ockerhaltige Produkte. Durch eine starke Verminderung der Durchlässigkeit der Geokunststoffe in Kombination mit einem hohen hydrostatischen Druck wurden unter anderem die Deckschichten verschiedener Deckwerke in den tidebeeinflussten Wasserstraßen Ems und Weser angehoben und beschädigt. Bisher wurden die Milieubedingungen, d.h. Grundwasser- und Oberflächenwasserbeschaffenheit sowie Aquifer- und Deckwerksmaterial, unter denen die Ockerbildung in geotextilen und mineralischen Filteranlagen auftritt, noch nicht systematisch untersucht. Im Rahmen des vorliegenden Beitrags werden im ersten Schritt aus theoretischen Untersuchungen und Datenanalysen von Grundwasser- und Oberflächenwasseruntersuchungen Kriterien zur Bewertung der Verockerungsneigung abgeleitet. Diese Kriterien bzw. DOCP (decisive ochre clogging parameters) zeigen in den Ästuaren Ems, Weser und Elbe Beträge an, die Verockerungserscheinungen begünstigen bzw. ermöglichen. Auf Basis dieser Untersuchungen werden im zweiten Schritt Randbedingungen für zukünftige systematische in-situ Untersuchungen an wasserbaulichen Filteranlagen sowie im experimentellen Modell abgeleitet.

Module 5 deals with the characteristics of projects, chances and challenges of project work and gives a basic overview of project planning and implementation tools and processes.

The PAQAF – the Pan-African Quality Assurance and Accreditation Framework – is an overarching framework for several action lines and instruments related to the convergence of the African Higher Education sector, and more specifically quality assurance and accreditation. It was adopted by the Specialized Technical Committee (STC) on Education, Science and Technology of the African Union Assembly in 2016. The implementation of some of the PAQAF’s action lines and the development of some of its instruments has been supported by the HAQAA initiative from 2015 to 2018 and is currently continued in the context of HAAQA2. Module 1 gives an overview of the PAQAF's deveopment and action lines.

Mechanical ventilation of buildings is generally based on steadily operating systems. This field is well known and established. But, an approach based on time-varied supply flow rates might improve indoor air quality, comfort, and energy consumption. Typical time-scales of the variation are in the order of seconds or minutes. Until now, the effects of unsteady ventilation scenarios are not fully described and so, reliable dimensioning rules are missing. Hence, with a better understanding of the flow in unsteady ventilation, systems can be calculated and optimised. To understand the effective mechanisms and derive functional relations between the flow field and variation parameters, full-field optical flow measurements are executed with a particle image velocimetry (PIV) system. Experiments are conducted under isothermal conditions in water in a small-scale room model (1.00 m × 0.67 m × 0.46 m) with two swirl ceiling diffusers, Reynolds-scaling assures similarity. In a series of experiments, the effects of different unsteady ventilation strategies on the flow fields are investigated and compared to steady conditions with the same mean exchange rate. Mean exchange rates, signal types, periods, and amplitudes are varied. Time-averaged normalised velocity fields already indicate notable differences between steady and unsteady cases especially for lower exchange rates: the distribution is more homogeneous in unsteady scenarios compared to steady conditions, and low-velocity areas are reduced while the mean velocity of the room increases. So, unsteady ventilation might be beneficial in terms of improved ventilation and energy savings in partial-load operation. Fast Fourier Transformation (FFT) analyses of the mean velocity for each field over the whole series detect the main frequency of the volume flow variation. By dividing the velocity field into smaller areas, this main frequency is still detected especially in the upper part of the room, but side frequencies play a role in the room as well.

A new approach to determine the elements carbon, hydrogen, nitrogen and oxygen (CHNO) in polymers by wavelength-dispersive X-ray fluorescence analysis (WDXRF) in combination with partial least squares (PLS) regression was explored. The quantification of CHNO was achieved by using the Rayleigh and Compton scattering spectra of an Rh X-ray tube from 84 different polymers. Concealed differences of the corresponding scattering spectra could be utilized to quantify CHNO in a multivariate manner. It was shown that the developed model was capable of determining these commonly non-measurable matrix elements in polymers using WDXRF. Furthermore, the influence of spectral resolution, which is given by the collimator and the crystal, on the prediction of CHNO was explored in this study. It was found that minimal spectral resolution led to the most accurate CHNO predictions. Information about matrix composition could be used to improve so-called semi-quantitative XRF methods based on fundamental parameters (FP) for the analysis of plastics, soil or other samples with high organic content.