Vizualisation through in blood vessels by digital holographic microscopy

Summary

    Digital holographic microscopy allows to refocus objects recorded out of focus and to measure, with a nanometric accuracy, the optical thickness of transparent particles. For those reasons, it is a valuable technology to measure fluxes in 3D. In particular, it is used to analyze dynamical fluxes of platelets and red blood cells. However, actual vessels are covered by an epithelium that may disturb the imaging quality. For this master thesis proposed in collaboration with the Laboratoire de Médecine Expérimentale (ULB – CHU Charleroi), we propose to study the methods to improve the image quality in presence of such disturbing layers. The master thesis will target both experimental and software works.

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Drop-by-drop manufacturing and testing of double-layer ultra-capacitors

Summary

    Additive manufacturing – a technique for manufacturing complex 3D object “layer-by-layer” – was first introduced in the ’70, but it is only at the beginning of the XXI century that this technique became widely used in many industrial applications, thanks to the introduction of more advanced tools and processes such as stereo-lithography and laser sintering. In recent years, 3D-printing triggered a real technological revolution still on-going. An intriguing possibility to achieve layered structures opportunely functionalized could consist in depositing and evaporating successive layers/drops of fluid dispersed with micro/nano particles. Playing on the dispersed phase materials (conductive/dielectric) it will be possible to manufacture a composite ultra-capacitor for hand-held devices and photovoltaic systems. The proposed work will then focus on characterizing those assemblies and their properties respect to current load, self-discharge, and lifetime.

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Smart management of de-icing systems for aeronautical and marine applications

Summary

    The formation of ice on airfoils is detrimental for the overall aerodynamics performances because it dramatically decreases the ability of the airfoil to create lift while sharply increasing drag. For an airplane to be approved to flight into icing conditions, it should be equipped with special ice-control systems that are extremely costly and inefficient in terms of power consumption. In general, the anti-icing system is turned on before the flight when ice is visually detected by direct inspection, a procedure that has been often criticized, especially after the air crash due to icing condition of Air Ontario Flight 1363 and American Eagle Flight 4184. The purpose of this work is to develop a smart management de-icing system, which is capable of detecting the formation of ice in real time as well as counteracting to eliminate the icy spots in an energy-efficient way. The device, based on an integrated thermoelectric matrix, is able to detect ice by sending power pulses across the matrix and analyze the response signals. Those latter should determine the position in the matrix of the icy spots and trigger the heaters closer to the detected point of ice formation.

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Lagrangian coherent structures in convective flows

Summary

    The basic approach aim is to fill the gap between real-life observations and classic nonlinear flow structures. Small particles transported by a fluid medium do not necessarily have to follow the flow. For a wide class of time-periodic incompressible flows inertial particles have a tendency to spontaneously align in one-dimensional dynamic coherent structures. The examples include manipulation and segregation of biological and synthetic microparticles, concentration, and transport of pollutants, nutrients, and plankton by oceanic currents and etc. We focus on experimentally observed types of coherence of small particles in oscillatory periodic flows, such as those in Figure 1, and then seek the dynamical structures that may create these forms. The proposed work will focus on a time formation of coherent structures in periodic flows caused by thermocapillary and buoyant convection. The experimentally observed structures will call for the theoretical explanation.

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Supercritical carbon dioxide as a green solvent

Summary

    The current practical interest in CO2 application is driven by peculiarly high solvent strength of CO2 in near- and supercritical conditions. The solvent strength of CO2 is highly tuneable, which allows easy separation of solute and solvent. This makes CO2 a highly desirable new ‘green’ solvent. We aim to make the breakthrough in comprehension of dynamics of mixtures in the states far from their thermodynamic equilibrium. We will finalize development of novel high-pressure set-up designed for measurement of the diffusion in CO2-rich liquid mixtures. These measurements are vital in view of CO2 sequestration in saline aquifers and depleted oil reservoirs. The proposed work will focus on study diffusion of hydrocarbons in supercritical CO2.

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Why molecules move along a temperature gradient?

Summary

    Molecules drift along temperature gradients, an effect called thermophoresis, the Soret effect, or thermodiffusion. The molecules of the mixture redistribute, forming concentration gradient that normally follows thermal one. The effect is slow and can play a visible role in large, geological, scales. It affects redistribution of species in underground oil reservoirs staying millions of years in geothermal gradient; it can affect redistribution of salinity in ocean producing impact on climate change. Finally, thermodiffusion allows the microscale manipulation of small particles. In liquids, its theoretical foundation is the subject of a long-standing debate initiated by Belgian Nobel prize winner I. Prigogine. The proposed work can be focused either on experimental or numerical side. An optical diagnostics of superior sensitivity and precision, namely interferometry, will be used for measurements of thermodiffusion coefficients in hydrocarbon mixture. On numerical side the redistribution of mixture components will be analysed using open software.

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