OCCAM Special Seminar (past)
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Fri, 10/05 11:30 |
Various (University of Oxford) |
OCCAM Special Seminar  |
OCCAM Common Room (RI2.28) |
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Fri, 12/04 11:30 |
Various |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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Fri, 08/03 11:30 |
Various (OCCAM) |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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Fri, 08/02 11:30 |
Various (OCCAM, University of Oxford) |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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Fri, 11/01 11:30 |
Various |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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Fri, 14/12/2012 11:30 |
Various |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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Fri, 09/11/2012 11:30 |
Various |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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Fri, 12/10/2012 11:30 |
Various |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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Thu, 20/09/2012 10:15 |
Guy Ramon (Princeton) |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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Composite membranes comprised of an ultra-thin coating film formed over a porous support membrane are the basis for state-of-the-art reverse osmosis (RO) and nanofiltration (NF) membranes, offering the possibility to independently optimize the support membrane and the coating film. However, limited information exists on transport through such composite membrane structures. Numerical calculations have been carried out in order to probe the impacts of the support membrane skin-layer pore size and porosity, support membrane bulk micro-porosity, and coating film thickness and morphology (i.e. surface roughness) on solvent and solute transport through composite membranes. Results suggest that the flux and rejection of a composite membrane may be fine-tuned, by adjusting support membrane skin layer porosity and pore size, independent of the properties of the coating film. Further, the water flux over the membrane surface is unevenly distributed, creating local ‘hot spots’ of high flux that may govern initial stages of membrane fouling and scaling. The analysis provides important insight on how the non-trivial interaction of support properties and film roughness may result in widely varying transport properties of the composite structure. In particular, the simulations reveal inherent trade-offs between flux, rejection and fouling propensity (the latter due to ‘hot spots’), which are purely consequences of geometrical factors, irrespective of materials chemistry. |
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Fri, 14/09/2012 11:30 |
Various |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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Tue, 11/09/2012 10:15 |
Samo Kralj (University of Maribor) |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
| Topological defects (TDs) are unavoidable consequence of continuous symmetry breaking phase transitions. They exhibit several universal features and often span apparently completely different systems. Particularly convenient testing ground to study basic physics of TDs are liquid crystals (LCs) due to their softness, liquid character and optical anisotropy. In the lecture I will present our recent theoretical studies of TDs in nematic LCs, which are of interest also to other branches of physics. I will first focus on coarsening dynamics of TDs following the isotropic-nematic phase transition. Among others we have tested the validity of the Kibble-Zurek [1,2] prediction on the size of the so called protodomains, which was originally derived to estimate density of TDs as a function of inflation time in the early universe. Next I will consider nematic LC shells [3]. These systems are of interest because they could pave path to mm sized scaled crystals exhibiting different symmetries. Particular attention will be paid to curvature induced unbinding of pairs of topological defects. This process might play important role in membrane fission processes. [1] W.H. Zurek, Nature 317, 505 (1985). [2] Z. Bradac et al., J.Chem.Phys 135, 024506 (2011) [3] S. Kralj et al., Soft Matter 7, 670 (2011); 8, 2460 (2012). | |||
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Fri, 27/07/2012 11:00 |
Various |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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Fri, 13/07/2012 11:30 |
Various |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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Fri, 08/06/2012 11:30 |
Various |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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Fri, 11/05/2012 11:30 |
Various |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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Tue, 08/05/2012 10:15 |
Nicolas Triantafyllidis (Ecole Polytechnique) |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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Stability plays an important role in engineering, for it limits the load carrying capacity of all kinds of structures. Many failure mechanisms in advanced engineering materials are stability-related, such as localized deformation zones occurring in fiber-reinforced composites and cellular materials, used in aerospace and packaging applications. Moreover, modern biomedical applications, such as vascular stents, orthodontic wire etc., are based on shape memory alloys (SMA’s) that exploit the displacive phase transformations in these solids, which are macroscopic manifestations of lattice-level instabilities. The presentation starts with the introduction of the concepts of stability and bifurcation for conservative elastic systems with a particular emphasis on solids with periodic microstructures. The concept of Bloch wave analysis is introduced, which allows one to find the lowest load instability mode of an infinite, perfect structure, based solely on unit cell considerations. The relation between instability at the microscopic level and macroscopic properties of the solid is studied for several types of applications involving different scales: composites (fiber-reinforced), cellular solids (hexagonal honeycomb) and finally SMA's, where temperature- or stress-induced instabilities at the atomic level have macroscopic manifestations visible to the naked eye. |
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Fri, 27/04/2012 10:15 |
Jimmy Moore (Texas A&M) |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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Fri, 20/04/2012 11:30 |
Various |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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Tue, 13/03/2012 10:15 |
Adriano Pisante (University of Rome Sapienza) |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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We discuss new symmetry results for nonconstant entire local minimizers of the standard Ginzburg-Landau functional for maps in ${H}^{1}_{\rm{loc}}(\mathbb{R}^3;\mathbb{R}^3)$ satisfying a natural energy bound. Up to translations and rotations, such solutions of the Ginzburg-Landau system are given by an explicit map equivariant under the action of the orthogonal group. More generally, for any $N\geq 3$ we characterize the $O(N)-$equivariant vortex solution for Ginzburg-Landau type equations in the $N-$dimensional Euclidean space and we prove its local energy minimality for the corresponding energy functional. |
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Fri, 09/03/2012 11:00 |
Various |
OCCAM Special Seminar |
OCCAM Common Room (RI2.28) |
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