R. Hamzaoui

Structure and magnetic properties of nanocrystalline mechanically alloyed Fe–10% Ni and Fe–20% Ni

Abstract The mechanical alloying technique has been used to prepare nanocrystalline Fe–10 and Fe–20 wt.% Ni alloys from powder mixtures. The structure and magnetic properties were studied by using X-ray diffraction and hysteresis measurements, respectively. For both alloys studied, a disordered body centered cubic solid solution forms after 24 h milling time. The higher the milling time, the larger the lattice parameter. The steady-state grain size is ≈10 nm. The reduction of the grain size increases the saturation magnetization and decreases the coercivity. Nanocrystalline Fe–10 and Fe–20 wt.% Ni have been shown to exhibit a soft magnetic behavior.

Optimal Carbon Nanotubes Concentration Incorporated in Mortar and Concrete

The mechanical properties and microstructure of modified mortar and concrete using Carbon NanoTubes (CNT) are experimentally studied at 7, 14, 28 and 90 curing days. Part of the formulation, CNT are dispersed in a liquid solution. Different concentrations ranging from 0.01% to 0.06% and 0.003% up to 0.01% are used for mortar and concrete, respectively. Mechanical testing of the modified materials reveals that maximum compressive strength is obtained for CNT concentrations close to 0.01%wt and 0.003%wt for mortar and concrete, respectively. The microstructural characterisation of the modified materials suggests that CNT act as bridges between pores and cracks leading to a reduction in porosity and in turn an increase of compressive strength.

Using the Fast Multi-Objective Genetic Algorithm to Improve the Urban Flood Modeling

In the present paper, a multi objective optimization approach based in Genetic Algorithm, Design Of Experiments and Response Surface Method strategies, is applied in order to predict the optimal CFD model parameters, allowing to model with high accuracy the 3D free surface flow of urban flood propagation retaining the total computation time (CPU-time) as short as possible. An experimental data set was used in this study as a validation means for numerical optimized models. We can say that the constraints in terms of computation time and accuracy, related to the application of 3D CFD modeling for flood propagation problems can be overcome by making an optimal choice of the advanced parameters of model. Index Terms—Urban flood modeling, computational fluid dynamics (CFD), multi objective optimization problems (MOOP), genetic algorithm (GA), response surface method (RSM), design of experiments (DOE).

Using a Laser Scanning to Construct a 3D Numerical Model to Study the Flooding Risk in Urban Area

Risk studies are very important to avoid human and economic losses. However the study cost becomes very expensive in some case when the site scale is very large. Thats why; using a numerical simulation with a small-scale model is considered as a suitable solution. In order to have accurate results on which we can rely to assess the risk, it is necessary to use sophisticated means to simulate with a high efficiency the study area. One of the very accurate means able to do that is based on laser scanning techniques. This article describes how a 3D laser scanning can provide quickly and accurately a 3D model of the study area reduced model for the risk simulation step. Moreover, the necessary processing steps in the laser software named Geomagic v12, are highlighted to achieve a neat 3-D model. The article also describes the preparation of the model for the numerical simulation step.