Tunis University

About: Tunis University is a education organization based out in Tunis, Tunisia. It is known for research contribution in the topics: Population & Thin film. The organization has 11745 authors who have published 15400 publications receiving 154900 citations. The organization is also known as: University of Tunis & UT.

Modeling and optimization of turning process parameters during the cutting of polymer (POM C) based on RSM, ANN, and DF methods

Abstract: The present work concerns an experimental study dealing with cutting parameters’ effects on the surface roughness, cutting force, cutting power, and productivity during turning of the polyoxymethylene (POM C) polymer. For that, a cutting tool made of cemented carbide was used. The work is divided into three steps. The first one deals with unifactorial tests, where the evolution of the machining parameters (roughness criteria, cutting force components, and cutting power) is investigated by varying cutting speed, feed rater, and depth of cut. The second part concerns the modeling of the output parameters: arithmetic roughness, cutting force, cutting speed, and material removal rate by using the results of a full factorial design (L27). The second step concerns the adoption of the two modeling techniques, which are the response surface methodology (RSM) and the artificial neural network (ANN). The obtained results related to two both techniques are compared in order to discern the most efficient one. The last step of the present research work concerns the multi-objective optimization using the desirability function (DF). The optimization was carried out according to three approaches, which are the “quality optimization,” “productivity optimization,” and the combination between the quality and productivity.

Copper-supported pillared clay catalysts for the wet hydrogen peroxide catalytic oxidation of model pollutant tyrosol

Abstract: The catalytic wet hydrogen peroxide oxidation of tyrosol, a major compound of the polyphenolic fraction present in olive oil mill wastewaters, was studied in batch and continuous reactors using copper-supported pillared clay catalysts under mild conditions. The catalysts were prepared by the solid-state reaction of Al-pillared clay synthesized with copper nitrate. The resultant materials were then calcined at 300 °C for 3 h under helium or oxygen. The catalytic activity of Cu-supported pillared clays was found to depend on the calcination method. The effects of several operating conditions were also studied. Our experimental results indicate that, under mild conditions and a stoichiometric amount of oxidant, the calcined material under helium (CuNHe catalyst) showed higher activity and stability (TOC abatement of roughly 80% and total elimination of tyrosol after 1 h reaction, without significant leaching of copper ions) than the calcined material under oxygen (CuNOxy). To better understand the catalytic behaviour of copper-supported pillared clay solids, fresh and used catalysts were characterized by X-ray diffraction, nitrogen adsorption, chemical analysis, temperature-programmed reduction (TPR), UV–visible diffuse reflectance spectroscopy, and transmission electron microscopy (TEM).