The aim of this study is to determine the phase indicator functions of a two-phase flow in an air-lift vacuum column. The outcome of this study is to master the hydrodynamics in a vertical column when determining the size, the velocities of the bubbles and the void rate then the gas-liquid interphase. The functions are the vacuum rate, the interface speed and bubble size, the flow rate and the speed of the liquid phase. The vacuum lift air column that is the subject of this study is based on the principle of air lift and flotation, all under vacuum. In its operation, the column combines hydraulic pumping, solute transfer and particle phase separation functions, which has the particularity of minimizing energy costs. The process of air-lift columns under the vacuum is still at the development stage and the experimental study of its hydrodynamics is one of the determining axes in the course of the exploration with a assessment to optimizing its design and functioning. The experiments were carried out on a vertical column composed of two concentric plexiglas tubes connected to a water recirculation tank and to a vacuum pump. For all experiments performed, demineralized water and salt water are used and the flow rate is measured using a flow meter. The experimental analysis is done using two-phase instrumentation consisting of a bi-probe and the use of experimental techniques has enabled a better understanding of the hydrodynamics of the two-phase flow.

The objective of this work research is to investigate the potential of using metallic powder mixed with electrical discharge machining (EDM) dielectric when machining hard electrically conductive materials. Nowadays, the development of industries requires hard materials for various applications. Machining the hard materials using the traditional processes lead to tool break and poor machined product. Even when the conventional EDM can machine hard material as long as it is electrically conductive materials, the machined parts still present drawbacks. Metallic powder mixed with EDM dielectric (PMEDM) was hypothesized to improve the machined part. The presence of metallic powder ensures uniform distribution of spark and the electrical density of the spark decreases which reduces craters, cracks and voids on machined surface. The transfer and deposit of alloying elements during powder mixed electrical discharge machining improve the machined surface properties particularly micro-hardness and fatigue. Discharge current (IP), gap voltage (GapV), ON-time (ON) and aluminum powder are selected as machined variable parameters and the output responses are fatigue performance, micro-hardness and surface topography. The workpiece material selected is molybdenum high speed steel. Micro-hardness was determined using micro-hardness tester device. The fatigue performance was determined using empirical equation. Analysis of material transfer was done using energy dispersive spectroscopy (EDS) attached to FESEM. EDS analysis involves the generation of an X-ray spectrum from the entire scan area of the SEM. The use of PMEDM improved the fatigue, the micro-harness and the machined surface morphology as the above-mentioned parameters increased.

In this study, we discussed the optical properties (Faraday rotation, transmittance and Merit factor) of two samples of magnetic liquids synthesized by co-precipitation and an additional hydrothermal synthesis of cobalt ferrite (CoFe2O4) developed according to the protocol developed by R. Massart at the PHENIX laboratory at Pierre and Marie Curie University in the form of ferrofluids. The measurements were carried out using the spectral polarimetric bench (400-1600 nm). The materials did not meet the standard and did not allow a good Faraday rotation due to their preparation conditions. Cobalt ferrite is a hard ferrimagnetic material, having many important applications in the field of magnetic storage and spintronics. The results show a very high spectral Faraday rotation in the Telecom range (1550 nm) with good transparency in the infrared of the transmittance spectra and a strong merit factor around 1550 nm, with a value of the order of 11°. For a cobalt ferrite magnetic liquid obtained hydrothermally.

In this work, we discuss the magneto-optical properties according to the orientation of 15nm-sized cobalt ferrite blocked in a silica matrix in comparison to the study done on 20nm-sized cobalt ferrite. This measurement shows that it is possible to increase the remanence of the Faraday effect by creating a magnetic orientation in the solid matrix, which is interesting for the production of self-polarized components. In addition, this remanence is greater for 15 nm than for 20 nm.A gelation field applied perpendicular to the plane of the layer therefore produces a preferential orientation of the magnetic moments in the direction of the field applied during the measurement.