Mode opératoire pour la réalisation d'essais de résistance sur blocs de terre comprimée

Sans résumé

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Membres du TC: Président: A. Hakimi, Maroc;Secrétariat: M. El Kortbi, Maroc; N. Yamani, Maroc;Membres. A. Acharhabi, Maroc; M. Ayeb; Maroc; N. P. Barbosa, Brésil; E. H. Bartali, Maroc; R. Bouqartacha, Maroc; A. Cherrabi, Maroc; P. Dencause, Maroc; S. El Amine, Maroc; A. Gilibert, Italie; S. Jalali, Portugal; A. Labib, Maroc; A. Lahbabi, Maroc; M. Martin, Burkina Fasso; R. Mattone, Italie; A. Mesbah, France; M. Olivier, France; H. Ouissi, Maroc; B. Pignal, France; S. Sanfo, Burkina Fasso; Z. Sekkat, Maroc; A. Thiombiano, Burkina Fasso.     

High level of laccases production by Trametes trogii culture on olive mill wastewater‐based media,application in textile dye decolorization

BACKGROUND: Laccases are receiving increasing attention as potential industrial enzymes in various applications. Therefore, it is important to find inexpensive and optimized media for large‐scale commercial production. The present work aims to valorize olive mill wastewater (OMW) by its use as base media for laccases production by Trametes trogii and use of the laccases produced for decolorizing textile dyes. RESULTS: A high yield of 25 120 U L^?1 of laccases was obtained at an OMW:water ratio of 80:20 enriched with 2 g L^?1 of urea corresponding to initial biochemical oxygen demand (BOD₅), chemical oxygen demand (COD) and total phenol concentrations of 18.4, 46 and 4.6 g L^?1 respectively. The partially purified laccases resulted in 85% decolorization of blue tubantin GLL 300 and black tubantin VSF 600, and 45% decolorization of blue solophenyl after 6 h of incubation. Subsequent additions of the same dye dose to the reaction mixture resulted in a very significant decrease in laccases activity after the third dye addition. CONCLUSION: The use of OMW for laccases production is a cost effective process. The laccases produced can be applied to the decolorization of textile wastewaters. Copyright © 2009 Society of Chemical Industry     

Inhibition of asphaltene flocculation in light crude oil: effect of pressure,temperature and inhibitor concentration

Abstract

In this study, a light crude oil sample was taken from Hassi Messaoud field to characterize its physicochemical properties. The asphaltene flocculation onset was determined in the dead oil by Flocculation Titrimeter equipment. The petroleum resins have been extracted from the same crude oil and tested as an inhibitor of asphaltene flocculation then their efficiency has been studied at different conditions of pressure and temperature. The results point out that the extracted resins may have two different effects on the onset point depending upon the operator conditions and the concentration of the added resins to crude oil.     

Multiscale Full-Field Strain Measurements for Micromechanical Investigations of the Hydromechanical Behaviour of Clayey Rocks

Abstract:  Digital image correlation techniques (DIC) are applied to sequences of optical images of argillaceous rock samples submitted to uniaxial compression at various saturation states at both the global centimetric scale of the samples and the local scale of their composite microstructure, made of a water-sensitive clay matrix and other mineral inclusions with a typical size of 50 μm. Various scales of heterogeneities are revealed by the optical technique. Not only is it confirmed that the clay matrix deforms much more than the other mineral inclusions, but it also appears that the deformation is very inhomogeneous in the matrix, with some areas almost not deformed, while others exhibit deformation twice the average overall strain (for a gauge length of 45 μm), depending on the local distribution of the inclusions. In almost-saturated rocks, overall heterogeneities are also linked to the presence of a network of cracks, induced by the preliminary hydric load. On such wet samples, DIC analysis shows that the overall strain results both from the bulk deformation of the sound rock, with deformation levels similar to those in dry samples, and the closing or opening of these mesoscopic cracks.     

Lupus interstitial cystitis. Apropos of a case]

The poor results obtained with the use of prosthesis in infrapopliteal arterial bypass grafting for critical limb ischaemia led to the introduction of several types of adjuvant arteriovenous fistula to improve the patency and limb salvage rates in patients who have no suitable autologous vein. The main aim of adjunctive arteriovenous fistula in infrageniculate prosthetic bypass is to accelerate the blood flow velocity through the prosthetic graft above the thrombotic threshold level. Since they are subject of great debate among vascular surgeons, the Authors have briefly reviewed the haemodynamic aspects and results reported with the use of such procedures.     

Joint production and setup control policies: an extensive study addressing implementation issues via quantitative and qualitative criteria

This paper addresses the production and setup control problem in unreliable multiproducts manufacturing system. Several decision criteria are considered in order to conduct an exhaustive comparative study of the two most complete control policies in the literature. The objective is to propose a production and setup control policy for the system under review. The first part of this work consists in analyzing the effect of the system parameters variation on the difference between the total costs of the two control policies studied. The best control policy in terms of cost will then be determined using a numerical example in the case of two identical product types and without the loss of generality of the problem. In the second part, two key performance indicators (KPIs): the cost and the customer satisfaction rate are simultaneously considered. The goal is to optimize the parameters of the policies studied, which minimize the total cost incurred while respecting customer satisfaction constraint. A discussion on the best control policy is conducted based on cost and customer satisfaction. An experimental resolution approach is used. It integrates combined discrete-continuous simulation models with statistical techniques of optimization such as design of experiments, analysis of variance, and response surface methodology. Finally, a discussion is conducted on the effects of other quantitative and qualitative criteria in order to determine the best control policy and to reach the best concerns of the company’s decision makers. These decision criteria are generally related to the storage space required constraint, the setups complexity, the implementation issue, and the complexity of the optimal control problem.     

Availability modelling and analysis of multi-product flexible transfer lines subject to random failures

Product requirements have changed dramatically in today’s industries forcing companies to implement flexible transfer lines manufacturing diverse product types. However, most of the researches dealing with transfer lines are so far limited to the mono-product and homogeneous lines (i.e., perfectly balanced). This paper addresses the problem of estimating the performance of multi-product, flexible transfer lines. Such lines are composed of several machines in series and can be used to manufacture a variety of products in a batch production environment. The machines are subject to random operation-dependent failures, and there are no intermediate buffers between adjacent machines. This paper aims to propose an analytical model for assessing the steady-state availability of such lines. A simulation model is also developed to mimic the real dynamic behaviour of flexible transfer lines. Thousands of production line configurations are tested in order to compare analytical results with simulation results. We used statistical tests to prove that the proposed formulae are exact and robust to model the steady-state availability of multi-product, unbuffered, flexible transfer lines subject to random failures.     

Ductility improvement of aluminum 1050A rolled sheet by a newly designed ball burnishing tool device

Conventional ball burnishing processes using a roller or a ball pressed against round or small flat surfaces have long been used to improve hardness, fatigue strength, and wear resistance of mechanical parts by plastic deformation. However, the treatment of large flat surfaces using conventional techniques is rarely considered because of its time consumption. In the present work, the optimal burnishing parameters of rolled sheets of aluminum 1050A are determined by means of a newly developed burnishing tool device especially designed to treat large flat surfaces with orders of magnitude reduction in burnishing time. Experiments were designed and performed on a machining center based on response surface methodology with central composite design. The burnished specimens were then tested to find the burnishing condition under which ductility was improved. This study has resulted in significant new insights into the effect of burnishing on the surface quality and workpiece properties of aluminum 1050A plates. A second-order mathematical model, validated using data obtained from atomic force microscopy, was developed to predict the surface roughness as functions of speed, force, and feed rate. The results indicate that burnishing of aluminum 1050A plates improves its ductility, but not its micro-hardness. Following the various burnishing conditions, the micro-hardness measurements range from 40 to 43?HV (50?g), indicating that there is little or no hardening. Although a moderate effect with varied degrees is found on the surface roughness as functions of the investigated parameters, the burnishing force has a significant effect on ductility. The results also indicate that lower values of roughness do not guarantee better ductility for aluminum 1050A plates. Furthermore, the effect of the burnishing loads on the residual stresses was found to depend on the feed direction.