"Grad students will be better suited for these projects, that's true, but I have already one grad student working on the water tank so an advanced undergrad will be good in that case."

1.- Weak Localization in a surface wave guide

In this project, we propose to study experimentally the possibility of wave localization in a surface wave guide with a random bottom. Following the work of Guazzelli et al. (J. Fluid Mech. (1988), vol. 186, pp. 53S-558), we plan measure experimentally the localization exponent and its dependence on frequency and wavelength. The surface waves will be excited by a wave maker driven by an electromagnetic shaker at low frequency (~5 Hz)  and the local wave amplitude will be measured by a capacitive probe.

2.- High-frequency effects in parametrically amplified surface waves

In this internship, we propose to study experimentally the effect of high-frequency harmonics in the stability and dynamical properties of parametrically amplified capillary surface waves. The local amplitude of the surface waves will be measured by means of a capacitive probe and the global structure of the pattern will be measured by means of a CCD camera which will record the light intensity reflected by the surface coming from an array of LEDs.

- The free-surfce wave Taylor-Couette experiment. We are continuously improving mechanical and electronic aspects of it. It has sophisticated instrument and needs an intern versed in computer-controlled measurements and/or machining.

- intermittent density explosions in a binary quasi-2D vibrated granular system (new project, better for a more advanced student, he or she will work supervised by myself, no grad student here).

- solid-liquid-like transition in a quasi-2D vibrated granular system. Experience with video image processing is desirable.

Proposal for a student internship: Dynamic Percolation Transition in Composites based on Polymers with Carbon Nanotubes.

F. Lund and H. Palza

Carbon nanotubes (CNT) in highly viscous matrices, such as polymers in the molten state, are systems in non-equilibrium conditions presenting several morphologies that depend on the flow conditions. The electric conductivity of a polyethylene (PE)-CNT composite has been measured in the melt under different oscillatory shear conditions using a parallel plate geometry. The proposed project involves rationalizing the data, first with a phenomenological model (I. Alig et al., ``Destruction and formation of a conductive carbon nanotube network in polymer melts: In-line experiments", Polymer 49, 3524-3532 (2008)), and then with a more elaborate model based on percolation theory (J. Obrzut et al., ``Shear-induced conductor-insulator transition in melt-mixed polypropylene-carbon nanotube dispersions" Phys. Rev. B 76, 195420 (2007)).

The experiment has been done by Lund's colleague from the Chemical Engineering Department, Professor Humberto Palza. Typical data are electrical conductivity as a function of time first under periodic shear, and then, after shear has been stopped, statically. The most striking aspect is the variation in conductivity as a function of time, typically spanning two orders of magnitude, in both regimes.

The parameters that are controlled with accuracy are shear rate, and frequency. CNT concentration is controlled less well. The modeling will involve simple kinetic (ordinary differential) equations and power law behavior. I do not foresee using master equations.

This project is about applying a theory to a body of data. Experience with mathematical software like Mathematica is desirable. It's not clear if it involves experimental work.

Whole-field speckle-based optical techniques for deformation assessment

To apply a speckle-based method to characterize the deformation mechanisms of cuticles (a thin layer of polymer covering the outer cell layer of plants and fruits). The combined application of ESPI (for generating the fringe patterns) and temporal phase-shifting (for retrieving the whole-filed values of the phase) will be used to follow the deformation progress of isolated cuticle membranes (CM) subjected to an uniaxial tensile load. The prior isolation of the CM will be carried out by using an aqueous solution containing enzymes. The cuticles of economically important fruits such as pear, apple, sweet cherry and grape will be tested.

Experience with laser optics and ccd capture and computer-controlled data aquisition are desirable.

Nanoparticles modified inorganic-organic hybrid polymers for corrosion protection of aluminium alloys
In this project we propose to incorporate encapsulated silver nanoparticles and ocrrosion inhibitor doped inorganic nanoparticles into the inorganic-organic hybrid films. The nanoparticles incorporated into the hybrid films will enhance corrosion-protection for aluminum alloys used in aircraft applications by adding self-healing and antimicrobial properties. The project has chemical and physical aspects. The chemical aspects are mainly associated with the processes of synthesis and functionalization of nanoparticles, as well as the processes of modification of polymers. On the other hand, the physical aspects are mainly associated with the determination of the mechanical properties of modified matrices, such as fracture resistance, hardness, residual tension and ageing. Although the importance of mechanical quantities of anticorrosive coating is very well recognized, the existing methods for their assessment are either limited by resolution or require film destruction.Thus, the proposal intends to develop non destructive methods for mechanical characterizing of thin films. For instance, nano-indentation techniques should provide valuable information on the Young modulus and the hardness films and nonlinear resonance methods should prove useful for the assessment of adhesion defects at the substrate film interface.

This center studies how thin films deform during growth and mechanical distortion. See the topics by Prof. Paez and Prof Cordero and Prof. Cerda.

Prof Bernal is making a microindentometer that will be used to apply point forces and see the deformation on the micron scale. He will use a piezoelectric device to get the deformation. It is the same as a atomic force microscope nanoindentometer, but at the microscale. They will develop speckle interferometric techniques to study deformation of biological tissues at the micron scale. Prof. Bernal has already a student working on it with some experience in speckle interferometric techniques.

This project also involves image acquisition, automated control over piezoelectric elements and force data aquisition. The experiment is being run by labview. The components have been tested individually. The job now is to combine them to make a working device.

Phenomenological Studies of Supersolidity

PDF file here.

It is mainly numerical work, developing codes and studying the phenomelogy.