Stationary spatially periodic and aperiodic solutions in membrane reactors

The formation of stationary spatially patterns is analysed for a detailed reaction mechanism of the oxidative dehydrogenation of ethane. In the first step, a simple steady-state model of an ideal plug flow membrane reactor is investigated by numerical bifurcation analysis. The model shows a complex nonlinear behaviour including period doubling bifurcations and aperiodic spatial patterns. In the next step, the influence of axial heat dispersion is studied. Finally, a more detailed model of a fixed bed membrane reactor is considered. It is found that pattern formation is possible under operation conditions realisable in a laboratory reactor.     

Fabrication Agency: Landesgartenschau Exhibition Hall

Advances in computation challenge established design approaches in architecture through a much deeper integration of form generation and materialisation. Tobias Schwinn , Research Associate at the Institute for Computational Design (ICD), University of Stuttgart, and Guest-Editor Achim Menges , Director of the ICD, introduce how the potentials and constraints of robotic fabrication can now be explored as generative drivers in agent-based design. This enables architectural innovation in unison with fabricability, structural capacity and spatial performance, as demonstrated by the Landesgartenschau Exhibition Hall in Schwäbisch Gmu"nd, Germany, the world's first building with a robotically fabricated segmented timber shell as its primary structure.     

James and the physical basis of emotion: A comment on Ellsworth.

It is argued that P. Ellsworth's (1994) interpretation of William James's theory of emotions is not supported by his writings. On the basis of textual evidence and systematic considerations, the authors try to show that, in line with the traditional view, James's theory holds that emotions are identical with feelings of bodily changes, of which autonomic changes are by far the most important ones (i.e., the only ones necessary and sufficient for emotions). Furthermore, the authors argue that James's question of the temporal priority of emotions versus bodily feelings makes good sense even if one acknowledges that these events usually show temporal overlap. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thermal simulation of pulsed direct laser interference patterning of metallic substrates using the smoothed particle hydrodynamics approach

This work presents a new approach to the thermal modelling of direct laser interference patterning (DLIP). The spatial and temporal evolution of the temperature distribution within metallic substrates, which are irradiated by nanosecond pulses during the DLIP process, is computed by means of a smoothed particle hydrodynamics (SPH) method. The developed model considers the conversion of laser energy into heat within a very thin surface layer, heat conduction into the bulk material and the effect of latent heat during involved phase transformations. The importance of proper determination of characteristic SPH parameters and adequate spatial resolution of the computational domain on the accuracy of the numerical solution is discussed in detail. The computed temperature distributions are in good agreement with the results of a previously developed FEM model and correspond very well to simultaneously performed experimental investigations.     

Initial steps of the metal-catalysed degradation of L-dehydroascorbic acid in acidic aqueous solutions

The initial steps of the degradation of L-de- hydroascorbic acid (L-DHA) in acidic aqueous solutions and the catalytic effect of different transition metal ions on this reaction were studied. The main product was identified as 3,6-furanosido-2,3-hexodiulosonic acid-2-hydrate (compound I) by GLC-MS and ¹³C-NMR, formed by lactone hydrolysis and hydration of the carbonyl group in the C-2 position of L-dehydroascorbic acid. In addition, number of other compounds were detected; they are formed from compound I by simple enolisation, lactonisation, hydration and dehydration reactions as well as by cleavage and formation of cyclic half acetal bonds. The chemical structures of these compounds were tentatively deduced by the mass spectra of their TMS derivatives and a reaction scheme for their formation is proposed. The velocity and the direction of the reactions were found to be strongly influenced by the presence of catalytic amounts of different transition metal ions. It was concluded that in acidic medium, in contrast to the situation in neutral and alkaline solutions, the opening of the lactone ring of L-DHA is, to a certain degree, a reversible reaction.