Virtual integration platform for computational fluid dynamics

Computational Fluid Dynamics (CFD) tools used in shipbuilding industry involve multiple disciplines, such as resistance, manoeuvring, and cavitation. Traditionally, the analysis was performed separately and sequentially in each discipline, which often resulted in conflict and inconsistency of hydrodynamic prediction. In an effort to solve such problems for future CFD computations, a Virtual Integration Platform (VIP) has been developed in the University of Strathclyde within two EU FP6 projects - VIRTUE and SAFEDOR1. The VIP provides a holistic collaborative environment for designers with features such as Project/Process Management, Distributed Tools Integration, Global Optimisation, Version Management, and Knowledge Management. These features enhance collaboration among customers, ship design companies, shipyards, and consultancies not least because they bring together the best expertise and resources around the world. The platform has been tested in seven European ship design companies including consultancies. Its main functionalities along with advances are presented in this paper with two industrial applications

Spin-dependent transport in metal/semiconductor tunnel junctions

This paper describes a model as well as experiments on spin-polarized tunnelling with the aid of optical spin orientation. This involves tunnel junctions between a magnetic material and gallium arsenide (GaAs), where the latter is optically excited with circularly polarized light in order to generate spin-polarized carriers. A transport model is presented that takes account of carrier capture in the semiconductor surface states, and describes the semiconductor surface in terms of a spin-dependent energy distribution function. The so-called surface spin-splitting can be calculated from the balance of the polarized electron and hole flow in the semiconductor subsurface region, the polarized tunnelling current across the tunnel barrier between the magnetic material and the semiconductor surface, and the spin relaxation at the semiconductor surface. Measurements are presented of the circular-polarization-dependent photocurrent (the so-called helicity asymmetry) in thin-film tunnel junctions of Co/Al2O3/GaAs. In the absence of a tunnel barrier, the helicity asymmetry is caused by magneto-optical effects (magnetic circular dichroism). In the case where a tunnel barrier is present, the data cannot be explained by magneto-optical effects alone; the deviations provide evidence that spin-polarized tunnelling due to optical spin orientation occurs. In Co/τ-MnAl/AlAs/GaAs junctions no deviations from the magneto-optical effects are observed, most probably due to the weak spin polarization of τ-MnAl along the tunnelling direction; the latter is corroborated by bandstructure calculations. Finally, the application of photoexcited GaAs for spin-polarized tunnelling in a scanning tunnelling microscope is discussed.

Highly efficient, dual state emission from an organic semiconductor

We report highly efficient, simultaneous fluorescence and phosphorescence (74% yield) at room temperature from a single molecule ensemble of (BzP)PB dispersed into a polymer host. The slow phosphorescence (208 ms lifetime) is very efficient (50%) at room temperature and only possible because the non-radiative rate for the triplet state is extremely low. The ability of an organic molecule to function as an efficient dual state emitter at room temperature is unusual and opens new fields of applications including the use as broadband down-conversion emitters, optical sensors and attenuators, exciton probes, and spin-independent intermediates for F\"orster resonant energy transfer

Erwinia berokkent pootgoedsector vele miljoenen schade

De besmetting met Erwinia ontwikkelt zich de laatste jaren tot een serieus probleem in de pootgoedsector. Voor telers ontstaat inkomensderving door lagere opbrengstprijzen en onbruikbare pootgoedvoorraden. Handelshuizen lijden schade door margedaling en reclameringen. Een aantasting van het imago van Nederlands pootgoed kan in de toekomst tot extra schade leiden

Dependence of the Frequency of the Kilohertz Quasi-Periodic Oscillations on X-ray Count Rate and Colors in 4U 1608-52

We present new results based on observations carried out with the Rossi X-ray Timing Explorer during the decay of an outburst of the low-mass X-ray binary (LMXB) and atoll source 4U 1608-52. Our results appear to resolve, at least in 4U 1608-52, one of the long-standing issues about the phenomenology of the kilohertz quasi-periodic oscillations (kHz QPOs), namely, the lack of a unique relation between the frequency of the kHz QPOs and the X-ray flux. We show that despite its complex dependence on the X-ray flux, the frequency of the kHz QPOs is monotonically related to the position of the source in the color-color diagram. Our findings strengthen the idea that, as in the case of Z sources, in the atoll sources the X-ray flux is not a good indicator of $\dot M$, and that the observed changes in the frequency of the kHz QPOs in LMXBs are driven by changes in $\dot M$. These results raise some concern about the recently reported detection of the orbital frequency at the innermost stable orbit in 4U 1820-30.Comment: Accepted for publication in The Astrophysical Journal Letters. Uses AAS LaTex v4.0 (5 pages plus 4 postscript figures

Lokaal veiligheidsbeleid in Nederland en Belgie: op zoek naar verschil

Veiligheid is sinds lang een verantwoordelijkheid van gemeenten. Maar het was tot vrij recent vooral de politie die zich met (sociale) veiligheid bezighield. Lokaal veiligheidsbeleid – als een expliciete verantwoordelijkheid van de gemeente, samen met vele andere partners – is een relatief recent verschijnsel. In dit artikel wordt de ontwikkeling van het lokale veiligheidsbeleid in Nederland en België, op hoofdlijnen, vergeleken. Bijzondere aandacht gaat uit naar de rol en positie van de gemeente. Wat opvalt is hoezeer de ontwikkelingen in beide landen op elkaar lijken. Zowel in België als in Nederland blijkt de nationale overheid een belangrijke, katalyserende rol te spelen bij het op gang brengen van herkenbaar lokaal veiligheidsbeleid. En in beide landen kost het veel moeite een eind te maken aan de oneigenlijke rol die de politie lange tijd gespeeld heeft; uitvoerend en beleidsmatig. In deze nieuwe bestuurlijke werkelijkheid ziet de gemeente zich voor nieuwe uitdagingen gesteld

Proximity to Sports Facilities and Sports Participation for Adolescents in Germany

Objectives - To assess the relationship between proximity to specific sports facilities and participation in the corresponding sports activities for adolescents in Germany. Methods - A sample of 1,768 adolescents aged 11–17 years old and living in 161 German communities was examined. Distances to the nearest sports facilities were calculated as an indicator of proximity to sports facilities using Geographic Information Systems (GIS). Participation in specific leisure-time sports activities in sports clubs was assessed using a self-report questionnaire and individual-level socio-demographic variables were derived from a parent questionnaire. Community-level socio-demographics as covariates were selected from the INKAR database, in particular from indicators and maps on land development. Logistic regression analyses were conducted to examine associations between proximity to the nearest sports facilities and participation in the corresponding sports activities. Results - The logisitic regression analyses showed that girls residing longer distances from the nearest gym were less likely to engage in indoor sports activities; a significant interaction between distances to gyms and level of urbanization was identified. Decomposition of the interaction term showed that for adolescent girls living in rural areas participation in indoor sports activities was positively associated with gym proximity. Proximity to tennis courts and indoor pools was not associated with participation in tennis or water sports, respectively. Conclusions - Improved proximity to gyms is likely to be more important for female adolescents living in rural areas

Awareness of group performance in a CSCL-environment: Effects of peer feedback and reflection

Phielix, C., Prins, F. J., & Kirschner, P. A. (2010). Awareness of group performance in a CSCL-environment: Effects of peer feedback and reflection. Computers in Human Behavior, 26(2), 151-161. doi:10.1016/j.chb.2009.10.011This study investigated the effects of a peer feedback tool and a reflection tool on social and cognitive performance during computer supported collaborative learning (CSCL). A CSCL-environment was augmented with a peer feedback tool (Radar) and a reflection tool (Reflector) in order to make group members aware of both their individual and their group behavior. Radar visualizes how group members perceive their own social and cognitive performance and that of their peers during collaboration along five dimensions. Reflector stimulates group members to reflect upon their own performance and the performance of the group. A 2x2 factorial between-subjects design was used to examine whether Radar and Reflector would lead to better team development, more group satisfaction, lower levels of group conflict, more positive attitudes toward problem-based collaboration, and a better group product. Results show that groups with Radar perceived their team as being better developed, experienced lower conflict levels, and had a more positive attitude towards collaborative problem solving than groups without Radar. The quality of group products, however, did not differ. The results demonstrate that peer feedback on the social performance of individual group members can enhance the performance and attitudes of a CSCL-group