4,802 research outputs found
Electric double layer structure close to the three-phase contact line in an electrolyte wetting a solid substrate
The electric double layer structure in an electrolyte close to a solid
substrate near the three-phase contact line is approximated by considering the
linearized Poisson-Boltzmann equation in a wedge geometry. The mathematical
approach complements the semi-analytical solutions reported in the literature
by providing easily available characteristic information on the double layer
structure. In particular, the model contains a length scale that quantifies the
distance from the fluid-fluid interface over which this boundary influences the
electric double layer. The analysis is based on an approximation for the
equipotential lines. Excellent agreement between the model predictions and
numerical results is achieved for a significant range of contact angles. The
length scale quantifying the influence of the fluid-fluid interface is
proportional to the Debye length and depends on the wall contact angle. It is
shown that for contact angles approaching 90{\deg} there is a finite range of
boundary influence.Comment: 6 pages, 9 figures;
http://link.aps.org/doi/10.1103/PhysRevE.86.02260
A discrete model for the apparent viscosity of polydisperse suspensions including maximum packing fraction
Based on the notion of a construction process consisting of the stepwise
addition of particles to the pure fluid, a discrete model for the apparent
viscosity as well as for the maximum packing fraction of polydisperse
suspensions of spherical, non-colloidal particles is derived. The model
connects the approaches by Bruggeman and Farris and is valid for large size
ratios of consecutive particle classes during the construction process,
appearing to be the first model consistently describing polydisperse volume
fractions and maximum packing fraction within a single approach. In that
context, the consistent inclusion of the maximum packing fraction into
effective medium models is discussed. Furthermore, new generalized forms of the
well-known Quemada and Krieger equations allowing for the choice of a
second-order Taylor coefficient for the volume fraction (-coefficient),
found by asymptotic matching, are proposed. The model for the maximum packing
fraction as well as the complete viscosity model are compared to experimental
data from the literature showing good agreement. As a result, the new model is
shown to replace the empirical Sudduth model for large diameter ratios. The
extension of the model to the case of small size ratios is left for future
work.Comment: 14 pages, 4 figure
Restructuring via internationalization: The auto industry's direct investment projects in Eastern Central Europe
Internationalization based on direct foreign investment is proving to be a key economic factor for the transformation economies of Eastern Central Europe. The decisive influence factors in this process are primarily major investments by groups based on longer-term strategies with the new locations. The effects linked with this at factory and regional levels are discussed in the study using the example of the auto and components industry. The sector was chosen because it is one of those very strongly linked with such major projects. The Volkswagen group's two prominent investment projects, Škoda in the Czech Republic and Audi in Hungary, are used to illustrate two things. First, that there was very accelerated implementation of the operational expansion of competences, in terms of new products, modern production structures, international competitiveness, and quality standards achieved. Second, that this was able to be done because of the especially highly skilled workers in the area. As a consequence, the firms have since been able to achieve not just strong positions within their respective national economies, but also within the VW group. However, by contrast, impulses for local industry emanating from the major investments have remained very limited. The study attributes this development to a coincidence of various causes. These include, above all, structural change in the auto industry over the past few years, the VW group's specific modernization path, and weak governance on the part of the transformation countries' governments. The results arising from the extended perspective of globalization and transformation underlying the group's project approach clearly indicate that increased international competition has strengthened the Eastern Central European region's comparative constellation of advantages. This consists of high-skill structures at low-cost conditions. It is unclear how far further reaching industrial upgrading at factory and regional levels can still be achieved in the countries in the face of increased East-West locational competition linked with this. The authors interpret this as a question of implementing new transnational arrangements limiting the negative consequences for locations in the West as well. --
Correlations of electromagnetic fields in chaotic cavities
We consider the fluctuations of electromagnetic fields in chaotic microwave
cavities. We calculate the transversal and longitudinal correlation function
based on a random wave assumption and compare the predictions with measurements
on two- and three-dimensional microwave cavities.Comment: Europhys style, 8 pages, 3 figures (included
Novellierung des Psychotherapeutengesetzes! Kritische Anmerkungen und Fragen zur derzeitigen Diskussion um die "Psychotherapeutische Direktausbildung" an Hochschulen/Universitäten
[Die Autorin] stellt Entwicklung und Stand der Novellierung des Gesetzes vor, die aufgrund der Bologna-Reformen notwendig wurde. Im Mittelpunkt steht die Frage nach einer psychotherapeutischen Zusatzausbildung auf MA-Niveau, die möglichst vielen Personen mit unterschiedlichem professionellen Hintergrund offen stehen sollte. Sie diskutiert kritisch, welche Konsequenzen das Gesetz in Zukunft für die psychotherapeutische Weiterbildung im Sinne einer Professionalisierung haben wird. (DIPF/Orig.
Herausforderungen der städtischen Szenerien an die Automatisierung von Fahrzeugbewegungen – wo sollen welche Anwendungen aktiviert werden?
Die Vielfalt der Stadtlandschaften in Europa schafft eine Unzahl an Herausforderungen für die Automati-sierung des Kraftfahrbetriebes im urbanen Straßennetz und für die praktische Anwendung von Funktiona-litäten in den Kraftfahrzeugen. Testfahrten mit solchen Fahrzeugen im Rahmen von „Living Labs“ erbringen punktuelle Erfahrungen und lassen selektive Erkenntnisse zu, werden aber vermutlich noch keine systema-tischen Grundlagen für den Einsatzbereich im urbanen Verkehrssystem liefern können. Dazu bedarf es einer Herangehensweise, die mit der Vielfalt der Erscheinungsformen städtischer Szenerien und mit der Unmenge an evozierten Szenen im Verkehrsgeschehen umzugehen weiß. Die verheißungsvollen Nutzanwendungen von Automatisierungsfunktionalitäten im Fahrbetrieb fokussieren bislang auf den Einsatz einzelner Kraftfahrzeuge und leiten daraus eine allgemeine Nützlichkeit für das Mobilitätssystem ab. Zur Nachweiserbringung fehlen aber noch Prüfroutinen, die für die allgemeine Zulassung in definierten örtlichen Einsatzbereichen ausreichend fundiert sind. Darüber hinaus werden die Mobilitäts-, die Verkehrs- und die Stadtplanung der Gebietskörperschaften gefordert sein, sich mit dem von der Industrie getriebenen Techno-logiethema auseinanderzusetzen, spätestens wenn die Entscheidungen anstehen, wo welche Anwendungen aktiviert werden oder ausgeschlossen bleiben sollen
An abstract machine for the execution of graph grammars
An abstract machine for graph rewriting is the central part of the middle
layer of the implementation of a grammar based graph rewriting system. It
specifies the interface between a compiler for graph grammars and a system
performing actual graph transformations. By the introduction of a middle
layer, the analysis of the given graph grammar can be used to optimize its
execution. The costs of expensive analysis are thus shifted from run to
compile time. Each implementation of the abstract machine can optimize the
utilization of available hardware. We give the specification of the state and
the instruction set of the abstract machine. For an example grammar we show
how compile time analysis can reduce execution time, and we present code
generation rules to implement a grammar on the abstract machine. In comparison
to abstract machines, well-known from the implementation of functional
languages, our machine can execute rewriting specified by graph grammars which
is far more general than graph reduction. The abstract machine for graph
rewriting is part of a project which addresses the efficient implementation of
the execution of graph grammars
Ferromagnetic manganites: spin-polarized conduction and competing interactions
Electronic properties of solids are vitally important for modern technology, one may think of microelectronics, magnetic data storage, communication technologies and others. Sometimes, it seems possible to postpone the step of fundamental understanding when starting the application of a new material. However, lasting success and discovery of principally new approaches is based on it ..
Simulation of the thermoforming process of UD fiber-reinforced thermoplastic tape laminates
In this work, initially, the requirements on a simulation model of the non-isothermal stamp forming process of unidirectional fiber-reinforced, and thermoplastic tape laminates are investigated experimentally. On this basis, different isothermal as well as a fully coupled thermomechanical simulation model under consideration of the crystallization kinetics are developed. For validation, a complex shaped geometry is simulated and compared to experimental forming results
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