Modelling of the dip-coating process

Dipcoating, wherein an object is withdrawn from a liquid bath, retaining a thin layer of liquid which then dries, is perhaps the simplest of coating techniques. SOLA Optical asked the MISG to investigate this process as a means of applying a protective coating to spectacle lenses. The theory, as proposed by the group, involves the 'lubrication' form of the equations of slow viscous flow. This yields an estimate of the wet coating thickness variation, which in turn depends on the liquid properties, the pull rate, and the lens curvature. When this thickness is reduced by the volatile fraction of the coating, predicted thicknesses are in rough agreement with reported values. Once applied, the liquid film drains downward and this effect is modelled numerically. An outline of a more complete model, allowing evaporation and drying, is also presented

A semi-analytic approach to the self induced motion of vortex sheets

The rolling up of the trailing vortex sheet produced by a wing of finite span was calculated as a series expansion in time. For a vorticity distribution corresponding to a wing with cusped tips, the shape of the sheet was found by summing the series using Pade approximants. The sheet remains analytic for some time but ultimately develops an exponential spiral at the tips. The centroid of vorticity was conserved to high accuracy

On the pressure field of nonlinear standing water waves

The pressure field produced by two dimensional nonlinear time and space periodic standing waves was calculated as a series expansion in the wave height. The high order series was summed by the use of Pade approximants. Calculations included the pressure variation at great depth, which was considered to be a likely cause of microseismic activity, and the pressure distribution on a vertical barrier or breakwater

Aluminum foil interconnects for solar cell panels

Commercially available sonic welding system and a specially-designed tip bonds aluminum foil interconnects to titanium-silver solar cell contacts

Improved Cross-correlation for Template Matching on the Laplacian Pyramid

Template matching via cross-correlation on Laplacian pyramid image architectures has been traditionally performed in a "coarse" to "fine" fashion. In the present paper, we show that by computing cross-correlation within each level of the pyramid independently, and considering the su, across (expanded) levels, a significant improvement in Peak to Correlation Energy (PCE) [9] is obtained. This result is illustrated with a number of numerical examples

Real-Time Restoration of Images Degraded by Uniform Motion Blur in Foveal Active Vision Systems

Foveated, log-polar, or space-variant image architectures provide a high resolution and wide field workspace, while providing a small pixel computation load. These characteristics are ideal for mobile robotic and active vision applications. Recently we have described a generalization of the Fourier Transform (the fast exponential chirp transform) which allows frame-rate computation of full-field 2D frequency transforms on a log-polar image format. In the present work, we use Wiener filtering, performed using the Exponential Chirp Transform, on log-polar (fovcated) image formats to de-blur images which have been degraded by uniform camera motion.Defense Advanced Research Projects Agency and Office of Naval Research (N00014-96-C-0178); Office of Naval Research Multidisciplinary University Research Initiative (N00014-95-1-0409

Computing with the Integrate and Fire Neuron: Weber's Law, Multiplication and Phase Detection

The integrate and fire model (Stein, 1967) provides an analytically tractable formalism of neuronal firing rate in terms of a neuron's membrane time constant, threshold and refractory period. Integrate and fire (IAF) neurons have mainly been used to model physiologically realistic spike trains but little application of the IAF model appears to have been made in an explicitly computational context. In this paper we show that the transfer function of an IAF neuron provides, over a wide parameter range, a compressive nonlinearity sufficiently close to that of the logarithm so that IAF neurons can be used to multiply neural signals by mere addition of their outputs. Thus, although the IAF transfer function is not explicitly logarithmic, its compressive parameter regime supports a simple, single neuron model for multiplication. A simulation of the IAF multiplier shows that under a wide choice of parameters, the IAF neuron can multiply its inputs to within a 5% relative error. We also show that an IAF neuron under a different, yet biologically reasonable, parameter regime can have a quasi-linear transfer function, acting as an adder or a gain node. We then show an application in which the compressive transfer function of the IAF model provides a simple mechanism for phase-detection: multiplication of 40Hz phasic inputs followed by low-pass filtering yields an output that is a quasi-linear function of the relative phase of the inputs. This is a neural version of the heterodyne phase detection principle. Finally, we briefly discuss the precision and dynamic range of an IAF multiplier that is restricted to reasonable firing rates (in the range of 10-300 Hz) and reasonable computation time (in the range of 25-200 milliseconds).National Institute of Mental Health (5R01MH45969-04); Office of Naval Research (N00014-95-1-0409

B+ and Ds+ Decay Constants from Belle and Babar

The Belle and Babar experiments have measured the branching fractions for B+ -> tau+ nu and Ds+ -> mu+ nu decays. From these measurements one can extract the B+ and Ds+ decay constants, which can be compared to lattice QCD calculations. For the Ds+ decay constant, there is currently a 2.1 sigma difference between the calculated value and the measured value.Comment: 10 pages, 8 figures, 1 table, contribution to the Tenth Conference on the Intersections of Particle and Nuclear Physics (CIPANP 2009), San Diego, Californi