Center Urbain Nord

Tunis, Tunisia

Center Urbain Nord

Tunis, Tunisia
SEARCH FILTERS
Time filter
Source Type

Ayed L.,University of Monastir | Achour S.,Diagnostic Immunitaire Et Valorisation A Linstitut Superieur Of Biotechnologie | Khelifi E.,Center Urbain Nord | Cheref A.,Center de Biotechnologie de la Technopole de Borj-Cedria | Bakhrouf A.,University of Monastir
Chemical Engineering Journal | Year: 2010

Azo dyes are widely used in textile dyeing which contains toxic and carcinogens compounds. So they must be treated before their discharge into the receptor medium. In this aim, this work is focused on the aerobic decolorization of water soluble azo dye Congo Red (CR) by bacterial consortium (Sphingomonas paucimobilis, Bacillus sp. and Staphylococcus epidermidis). The effect of different combinations of these three strains cultivated in the pure culture in mineral salts medium (MSM) on the decolorization of Congo Red (cell density fixed at OD600=1 with the addition of 750ppm of the dye) was studied using equilateral triangle diagram and mixture experimental design to assess color and COD removal during species growth. Using software analysis (Minitab 14.0), the formulation of pure culture in MSM can be optimized for several responses and the best formulation can be obtained. The results suggested that the highest decolorization and chemical oxygen demand (COD) rates were 100% and 98%, respectively. Very high regression coefficient between the variables and the responses: decolorization and COD removal were R 2=32.69% and R 2=52.25%, respectively indicating an excellent evaluation of experimental data by polynomial regression model. FTIR (Fourier transform infrared) and UV-vis analysis confirmed the biodegradation of Congo Red by the bacterial consortium. The produced metabolites were extracted and their phytotoxicity study suggested their low toxicity. © 2010 Elsevier B.V.


Saad R.B.,Center Urbain Nord | Pillet C.-A.,Aix - Marseille University | Pillet C.-A.,University of Toulon
Journal of Mathematical Physics | Year: 2014

We consider an ideal Fermi gas confined to a geometric structure consisting of a central region - the sample - connected to several infinitely extended ends-the reservoirs. Under physically reasonable assumptions on the propagation properties of the one-particle dynamics within these reservoirs, we show that the state of the Fermi gas relaxes to a steady state. We compute the expected value of various current observables in this steady state and express the result in terms of scattering data, thus obtaining a geometric version of the celebrated Landauer-Büttiker formula. © 2014 AIP Publishing LLC.


Ayed L.,University of Monastir | Khelifi E.,Center Urbain Nord | Jannet H.B.,University of Monastir | Miladi H.,University of Monastir | And 3 more authors.
Chemical Engineering Journal | Year: 2010

The use of chemometric methods such as response surface methodology (RSM) based on statistical design of experiments (DOEs) is becoming increasingly widespread in several sciences such as analytical chemistry, engineering and environmental chemistry. In the present study, the decolorization and the degradation efficiency of Methyl Orange (MO) was studied using a microbial consortium. The microbial growth of Sphingomonas paucimobilis, Bacillus cereus ATCC14579, Bacillus cereus ATCC11778 is well in the presence of MO (750. ppm) within 48. h at pH 7 and 30 °C. In fact, these microorganisms were able to decolorize and to degrade MO to 92%. The degradation pathway and the metabolic products formed during the degradation were also predicted using UV-vis, Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy analysis. Under optimal conditions, the bacterial consortium was able to decolorize completely (>84%) the dye within 48. h. The color and COD removal were 84.83% and 92.22%, respectively. A significant increase in azoreductase, lignin peroxidase and laccase activities in the cells were obtained after complete decolorization. Phytotoxicity study using plants showed no toxicity of the produced products. © 2010 Elsevier B.V.


Hadda H.,Center Urbain Nord | Hajji M.K.,National Engineering School of Tunis | Dridi N.,National Engineering School of Tunis
RAIRO - Operations Research | Year: 2015

In this paper we develop new elimination rules and discuss several polynomially solvable cases for the two-stage hybrid flow shop problem with dedicated machines. We also propose a worst case analysis for several heuristics. Furthermore, we point out and correct several errors in the paper of Yang [J. Yang, A two-stage hybrid flow shop with dedicated machines at the first stage. Comput. Oper. Res. 40 (2013) 2836-2843]. © EDP Sciences, ROADEF, SMAI 2015.


Hadda H.,Center Urbain Nord | Dridi N.,National Engineering School of Tunis | Hajri-Gabouj S.,Center Urbain Nord
4OR | Year: 2010

In this paper, we deal with the two-machine flow shop scheduling problem having an unavailability interval on the first machine, and nonresumable jobs. We first present an enhancement procedure that, once applied to any arbitrary solution, produces a schedule that is at most equal 2 times the optimal makespan. We then develop an improved heuristic, with a relative worst-case error of 3/2. © 2009 Springer-Verlag.


Ben Bachouch R.,INSA Lyon | Ben Bachouch R.,Center Urbain Nord | Guinet A.,INSA Lyon | Hajri-Gabouj S.,Center Urbain Nord
International Journal of Production Economics | Year: 2012

In this paper we investigate the hospital bed management problem. Constrained by budgetary cuts, French hospitals must efficiently manage shared resources, especially beds, which are allocated to acute and elective patients. Nurses therefore have to manage beds and to plan their use according to the demand, including cases of acute patients from the emergency ward. Managing hospital bed planning is difficult due to the demand increase and restricted hospital resources. Our aim is to propose a decision support tool based on an integer linear program for hospital bed planning, considering two classes of patients: elective and acute cases. We take into account several constraints: incompatibility between pathologies, no mixed-sex rooms, continuity of care, etc. In order to solve the proposed model and to compare the results, we use three solver softwares: GLPK, LINGO of LINDO SYSTEMS and CPLEX of ILOG. © 2012 Elsevier B.V. All rights reserved.


Hadda H.,Center Urbain Nord
International Journal of Production Economics | Year: 2015

In Allaoui H., Lamouri S., Artiba A., Aghezzaf E., Simultaneously scheduling n jobs and the preventive maintenance on the two-machine flow shop to minimize the makespan. International Journal of Production Economics 2008, 112, 161-167, several results are proposed. We show in this note that some of them are false. We also extend the analysis for some other results. © 2014 Elsevier B.V. All rights reserved.


Darmoul S.,King Saud University | Pierreval H.,CNRS Laboratory of Informatics, Modeling and Optimization of Systems | Hajri-Gabouj S.,Center Urbain Nord
Engineering Applications of Artificial Intelligence | Year: 2013

One of the major issues in the monitoring and control of manufacturing systems is to determine how to effectively deal with unexpected disruptions (e.g. material unavailability, resource failures, unavailability of operators, rush orders, etc.). Existing approaches and tools offer few concepts that are specific enough and sufficiently generic to help in handling a broad variety of such unexpected events. The biological immune system potentially offers interesting features to face the threats (bacteria, viruses, cancers, etc.) that may harm an organism. This research aims to investigate this potential for the monitoring and control of manufacturing systems at the occurrence of disruptions. Based on analogies that we point out, we suggest a framework to help with the design of software tools that are more able to assist decision makers in dealing with various types of disruptions occurring in a manufacturing system. A first prototype implementation, developed using a multi agent approach, contributes to show the feasibility and the interest of this immune based framework. © 2012 Elsevier Ltd. All rights reserved.


In this paper we deal with the two-machine flow shop scheduling problem with several availability constraints on the first machine, under the resumable scenario. We first develop an improved algorithm with a relative worst-case error bound of 4/3. We then present a polynomially solvable case. © 2010 Springer-Verlag.


Drira A.,French Institute for Advanced Mechanics | Drira A.,Center Urbain Nord | Pierreval H.,French Institute for Advanced Mechanics | Hajri-Gabouj S.,Center Urbain Nord
Engineering Applications of Artificial Intelligence | Year: 2013

One of the problems encountered in the design of manufacturing systems is how to arrange the machines on the surface of the workshop, which is commonly referred to as a layout problem. Such a problem has been widely investigated in the literature. Most approaches use optimization technique to determine the position of each facility, assuming that the required data is available. Unfortunately, this assumption is often unrealistic, since the study design of a workshop is obviously conducted much before it is operating, so that data related to customer demands, for example, is generally not known with enough precision. Indeed, if good forecasts about what is to be produced in the next weeks can be available, they will obviously become more and more unreliable as the considered period of time will increase, so that layout found using classical approaches can turn out not to be relevant on the medium or long term. We propose an approach to design a robust layout in a context where the certainty of the information available decreases over time, which is usually the case for real applications. We propose a resolution approach based on a fuzzy evolutionary algorithm, which includes uncertain customer demands for each product. We show how this problem can be stated as a fuzzy dynamic layout problem with growing uncertainty over time. We suggest an evolutionary algorithm with adapted operators. Their performances are first tested using 2crisp layout problems already published. Then the impact of increasing uncertainty is studied using a suggested benchmark. The results of our experiments show the importance of considering the degradation of the information for designing robust layouts. © 2012 Elsevier Ltd. All rights reserved.

Loading Center Urbain Nord collaborators
Loading Center Urbain Nord collaborators