Thermoforming of foam sheet

Thermoforming is a widely used process for the manufacture of foam sheet products. Polystyrene foam food trays for instance can be produced by first heating the thermoplastic foam sheet, causing the gas contained to build up pressure and expand, after which a vacuum pressure can be applied to draw the sheet in the required form on the mould. This production method appears to be a very sensitive process with respect to e.g. the sheet temperature, the pressures applied and the cooling time. More problems can be foreseen when for environmental reasons the blowing agent will be adapted (for instance replaced by a gas with a lower molecular weight). To gain more insight in the occuring phenomena the large deformations of a foam structure have been analysed using finite element modelling. To this end a constitutive model has to be defined. Starting from the basic theory given by Gibson & Ashby [1], the behaviour of a closed cubic cell has been elaborated for large strains. The total stiffness is then the sum of the contributions of the edges and faces of the cell and the gas contained in it. The large deformations cause anisotropy of the cells [2], which influences their tangential stiffness. The constitutive model developed here includes the effects of internal gas pressure and the evolving anisotropy

Market liquidity around earnings announcements

Prior literature indicates that bid-ask spreads are higher and depths are lower around earnings announcements than during non-announcement periods. This thesis investigates two important aspects of this drop in market liquidity, namely (a) the ability of management to mitigate the drop in market liquidity around earnings announcements by using their discretion to announce the earnings news during non-trading instead of trading hours and (b) the conjecture that the drop in market liquidity before earnings announcements relates to the richness of the information environment. The study confirms the idea that the intraday timing of earnings announcements affects the drop in market liquidity. A robust relationship between the information environment and the drop in market liquidity before earnings announcements cannot be documented however

Waterbesparing in de boomteelt

Research on water requirements for nursery crops. Aim of this research is giving advice on water supply for all nursery crop

Pilot Experiments with Electrodialysis and Ozonation for the Production of a Fertilizer from Urine

Pilot tests were performed with a process combination of electrodialysis and ozonation for the removal of micropollutants and the concentration of nutrients in urine. In continuous and batch experiments, maximum concentration factors up to 3.5 and 4.1 were obtained, respectively. The desalination capacity did not decrease significantly during continuous operation periods of several weeks. Membrane cleaning after 195 days resulted in approximately 35% increase in desalination rate. The Yeast Estrogen Screen (YES), a bioassay that selectively detects oestrogenic compounds, confirmed that about 90% of the oestrogenic activity was removed by electrodialysis. HPLC analysis showed that ibuprofen was removed to a high extent, while other micropollutants were below the detection limit. In view of the fact that ibuprofen is among the most rapidly transported micropollutants in electrodialysis processes, this result indicates that electrodialysis provides an effective barrier for micropollutants. Standardised plant growth tests were performed in the field with the salt solution resulting from the treatment by electrodialysis and subsequent ozonation. The results show that the plant height is comparable to synthetic fertilisers, but the crop yield is slightly lower. The latter is probably caused by volatilisation losses during field application, which can be prevented by improved application technologies

When your hearing fails you: Hearing loss determinants, psychosocial consequences, and possible interventions following screening in older adults

Festen, J.M. [Promotor]Deeg, D.J.H. [Promotor]Kramer, S.E. [Copromotor

Progression paths in children’s problem solving: The influence of dynamic testing, initial variability, and working memory

The current study investigated developmental trajectories of analogical reasoning performance of 104 7- and 8-year-old children. We employed a microgenetic research method and multilevel analysis to examine the influence of several background variables and experimental treatment on the children’s developmental trajectories. Our participants were divided into two treatment groups: repeated practice alone and repeated practice with training. Each child received an initial working memory assessment and was subsequently asked to solve figural analogies on each of several sessions. We examined children’s analogical problem-solving behavior and their subsequent verbal accounts of their employed solving processes. We also investigated the influence of verbal and visual–spatial working memory capacity and initial variability in strategy use on analogical reasoning development. Results indicated that children in both treatment groups improved but that gains were greater for those who had received training. Training also reduced the influence of children’s initial variability in the use of analogical strategies with the degree of improvement in reasoning largely unrelated to working memory capacity. Findings from this study demonstrate the value of a microgenetic research method and the use of multilevel analysis to examine inter- and intra-individual change in problem-solving processes

An Interpretation of Late Quaternary Glacial Flow Indicators in the Baie des Chaleurs Region, Northern New Brunswick

A sequence of late Quaternary geologic events in northern New Brunswick is determined from striation analysis derived from published data, open file reports, and field research conducted by the authors since 1985. These data are integrated with clast provenance and clast fabric trend analysis, as well as information from other studies in the surrounding area. South of the Baie des Chaleurs, a complicated Late Wisconsinan glacial history is preserved in the form of erosive features including nailhead striae, miniature crag-and-tails, and various scars, striations, and fractures. The rarity of sedimentary deposits and datable materials precludes simple stratigraphie interpretation. Based on over 1,000 striation sites, we conclude four major phases of glacial flow affected the area during the Late Wisconsinan: 1) an early flow to the southeast which reflects local Appalachian ice; 2) a second phase of glacial flow to the east indicating a Laurentide ice influence in western New Brunswick; 3) a third phase of glacial flow to the north-northeast, which may represent ice response to drawdown in the Baie des Chaleurs; and 4) a final multidirectional flow indicating localized ice response during the last stages of Late Wisconsinan glaciation. The absence of Canadian Shield erratics in northern New Brunswick is explained in terms of ice streaming along the St. Lawrence channel beneath a southward-flowing Laurentide Ice Sheet. Basal ice debris (including Shield erratics) was apparently truncated and removed by the obliquely flowing ice stream, leaving relatively clean ice in the Ice Sheet as it entered Gaspésie and ultimately New Brunswick.On a déterminé la séquence des événements géologiques du Quaternaire supérieur survenus dans le nord du Nouveau-Brunswick à partir de l'analyse des stries tirée de diverses sources. Au sud de la baie des Chaleurs, l'évolution glaciaire complexe du Wisconsinien supérieur peut être retracée à partir des formes d'érosion glaciaire dont les clouures, les crag-and-tails miniatures, les cicatrices de toutes sortes, les stries et les fractures. La rareté des sédiments et des matériaux pouvant être datés excluent toute interprétation fondée sur la stratigraphie. En s'appuyant sur plus de 1000 sites de stries, on croit que la région a connu quatre épisodes glaciaires pendant le Wisconsinien supérieur: 1 ) le premier mouvement, de faible importance, s'est fait vers le SE en provenance des Appalaches; 2) le deuxième écoulement glaciaire vers PE démontre la force des glaces laurentidiennes au nord du Nouveau-Brunswick; 3) le troisième mouvement glaciaire vers le NNE pourrait être une réaction à l'affaissement qui s'est produit dans la baie des Chaleurs; 4) le dernier mouvement multidirectionnel s'est fait à partir de calottes localisées pendant les derniers stades de la glaciation wisconsinienne. On explique l'absence des blocs erratiques dans le nord du Nouveau-Brunswick par un écoulement des glaces le long du chenal laurentien interrompant l'Inlandsis laurentidien s'écoulant vers le sud. Les débris glaciaires de fond (y compris les blocs erratiques du Bouclier) ont apparemment été tronqués et enlevés par un courant glaciaire oblique, épurant ainsi la glace qui pénétrait en Gaspésie, puis au Nouveau-Brunswick.Een Interpretatie van Laat-glaciale Ijsbewegingsindicaties in de Chaleur Bay Regio, Noord New Brunswick. De Kwartair geologische kartering van noord New Brunswick begon met de studies van Robert Chalmers aan het einde van de 19e eeuw. Sindsdien zijn verschillende pogingen gedaan om de glaciale geschiedenis van dit gebied te ontravelen en uiteindelijk zijn Chalmers ideeen herontdekt en aangepast aan moderne theorien en modellen van glaciale processen en isostasie. De afwezigheid van stratigrafische secties en de aanwezigheid van vêle glaciale erosieve en morphologische vormen heeft geleid tot de ontwikkeling van een "erosie-stratigrafie ". Deze informatie wordt gesteund door till lithologische en ges-teente orientatie studies. Het resultaat van dit gedetailleerde karterings project is de her-kenning van 4 verschillende ijs-bewegingen. Datering van deze gebeurtenissen is een probleem vanwege een gebrek aan dateer-bare materialen. Een eerste zuidoostelijke ijsbeweging is geregistreerd in het oostelijke deel van het gebied en in de Chaleur Coastal Plain. De tweede en sterkste gebeurtenis geeft een oostwaartse ijsbeweging te zien, die waarschijnlijk gedurende het gehele Wisconsinan (Weichselien) en mogelijk het gehele Pleistoceen van belang kan zijn geweest. Een derde ijsbeweging is in noord-oostelijke richt-ing in de Baie des Chaleurs. In een latere fase, lokale ijsbewegingen vonden plaats in verschillende richtingen vanaf de hooglanden en mogelijk vanuit Baie des Chaleurs. Er is een poging gedaan deze gebeurtenissen in een régionale context te plaatsen, waarin de interactie van de Laurentide Ice Sheet met het Appalachian Ice Complex en het concept van een Laurentian ijsstroomkanaal centraal staan

Melting of Polydisperse Hard Disks

The melting of a polydisperse hard disk system is investigated by Monte Carlo simulations in the semigrand canonical ensemble. This is done in the context of possible continuous melting by a dislocation unbinding mechanism, as an extension of the 2D hard disk melting problem. We find that while there is pronounced fractionation in polydispersity, the apparent density-polydispersity gap does not increase in width, contrary to 3D polydisperse hard spheres. The point where the Young's modulus is low enough for the dislocation unbinding to occur moves with the apparent melting point, but stays within the density gap, just like for the monodisperse hard disk system. Additionally, we find that throughout the accessible polydispersity range, the bound dislocation-pair concentration is high enough to affect the dislocation unbinding melting as predicted by Kosterlitz, Thouless, Halperin, Nelson and Young.Comment: 6 pages, 6 figure

Financial Accounting, te praktisch voor theorie en te theoretisch voor de praktijk?

Is Financial Accounting too practical for research? I was recently asked this question during an interview, and it surprised me. Why would it be too practical for research? Can we only conduct research on topics that are not related to practice? Or is it not clear what Financial Accounting is really about, and that it is more than bookkeeping? Using examples of recent research, I show why Financial Accounting is certainly not too practical for theory. The question whether Financial Accounting research is too theoretical for practice is a more challenging question. Can we do quality research within the field of financial reporting and is this research relevant to business? Does our research have any societal relevance in the current dynamic environment? I conclude that Financial Accounting research is certainly relevant, but that the accounting professional active in the business community only benefits to a very limited extent. In addition, I discuss two initiatives, namely the Ernst & Young Academic Network and the Erasmus Marketing & Accounting Research Center that will prevent us from conducting research that is too theoretical for practice