UNE TYPOLOGIE POUR LES QUARTIERS INFORMELS A BISKRA

Au milieu d’une crise économique contraignante ayant provoqué une hausse vertigineuse des prix de terrain à bâtir, de matériaux de construction et même de main d’oeuvre, le logement en Algérie devient aujourd’hui inaccessible y compris pour les couches moyennes. La faiblesse des réalisations du logement social urbain, la rapide croissance démographique et l’exode rural massif ont favorisé la naissance et la prolifération de l’habitat informel. La ville de Biskra n’a pas échappé à ce fléau. Cet article tente une approche typologique des quartiers démunis pour une meilleure compréhension des mécanismes de leur évolution et de la manière de les aborder en vue d’améliorer les conditions de vie de leurs habitants

LE DECONGESTIONNEMENT URBAIN ET LE DESEQUILIBRE MICRO REGIONAL. CAS DE BISKRA

RESUMELa ville de Biskra, à l’instar d’autres villes algériennes, connait des problèmes de congestion urbaine. La concentration desinvestissements surtout dans les secteurs secondaire et tertiaire au niveau du chef-lieu de wilaya a drainé une forte populationrurale. Cette dernière, conjuguée au taux élevé du croît naturel, a favorisé le déséquilibre de l’armature spatiale du systèmewilayal et par conséquent la congestion urbaine de la ville primatiale. Cette maladie urbaine est expliquée par undéveloppement à deux vitesses. Le chef-lieu de Wilaya croît plus vite que son corps wilayal et prend des dimensionsdisproportionnées par rapport à l’ensemble. Les conséquences ne peuvent être que néfastes. La pression sur les voies decirculation, la croissance du parc automobile, la surcharge des équipements et des activités sont devenus les caractéristiques dela ville de Biskra qui n’arrive plus à répondre aux besoins de ses habitants. Cette recherche tente de démontrer la relation entrela congestion urbaine de la ville primatiale et le déséquilibre de l’armature spatiale de son système urbain micro régional.MOTS CLES: Congestion urbaine, armature urbaine, déséquilibre de l’armature spatial

Removal of cationic pollutants from water by xanthated corn cob: optimization, kinetics, thermodynamics, and prediction of purification process

The removal of Cr(III) ions and methylene blue (MB) from aqueous solutions by xanthated corn cob (xCC) in batch conditions was investigated. The sorption capacity of xCC strongly depended of the pH, and increase when the pH rises. The kinetics was well fitted by pseudo-second order and Chrastil’s model. Sorption of Cr(III) ions and MB on xCC was rapid during the first 20 min of contact time and, thereafter, the biosorption rate decrease gradually until reaching equilibrium. The maximum sorption capacity of 17.13 and 83.89 mg g-1 for Cr(III) ions and MB, respectively was obtained at 40 °C, pH 5 and sorbent dose 4 g dm-3 for removal of Cr(III) ions and 1 g dm-3 for removal of MB. The prediction of purification process was successfully carried out and the verification of theoretically calculated amounts of sorbent was confirmed by using packed-bed column laboratory system with recirculation of the aqueous phase. The wastewater from chrome plating industry was successfully purified, i.e. after 40 min concentration of Cr(III) ions was decreased lower than 0.1 mg dm-3. Also, removal of MB from the river water was successfully carried out and after 40 min removal efficiency was about 94 %

Les reactions catalytiques gaz-solide organique. Etude de la mise en contact des reactifs. Elaboration d'un modele cinetique

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 84175 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Influence of five model parameters on the performance of a CO

Rigorous packed-bed absorber modeling and simulation are significant for post-combustion CO2 capture processes design. Hence, a good knowledge and judicious selection of model parameters are essential to ensure reliable predictions. In this paper, the reactive absorption of CO2 into loaded aqueous monoethanolamine solution was modeled, furthermore, the effects of five different parameters (kinetic model, enhancement factor, enthalpy of absorption, CO2 diffusivity, and vapor pressure) were investigated. Finally, this study revealed that some model parameters have a large influence on the column performance, contrary to others. In addition, methods and correlations that generally provide more accurate predictions of the empirical data relative to the other cases involved in this research were determined for each model parameter. It was also found that the model deviation was reduced by 18% and 4% for the liquid temperature and liquids CO2 loading profiles, respectively, while comparing between the worst and the best case

Comments on the fractional parts of Pisot numbers

summary:Let $L(\theta ,\lambda )$ be the set of limit points of the fractional parts $\lbrace \lambda \theta ^{n}\rbrace$, $n=0,1,2, \dots$, where $\theta$ is a Pisot number and $\lambda \in \mathbb{Q}(\theta )$. Using a description of $L(\theta ,\lambda )$, due to Dubickas, we show that there is a sequence $(\lambda _{n})_{n\ge 0}$ of elements of $\mathbb{Q}(\theta )$ such that $\operatorname{Card}\,(L(\theta ,\lambda _{n}))< \operatorname{Card}\,(L(\theta ,\lambda _{n+1}))$, $\forall$ $n\ge 0$. Also, we prove that the fractional parts of Pisot numbers, with a fixed degree greater than 1, are dense in the unit interval

1,2-bis(4-chlorobenzylidene)Azine as new and effective corrosion inhibitor for copper in 0.1 N HCl A combined experimental and theoretical approach

International audienc

Evaluation of the effect of Tetramethylammonium hydroxide on the corrosion inhibition of A9M steel in industrial water an experimental, morphological and MD simulation insights.

International audienceCorrosion inhibition performance of Tetramethylammonium hydroxide (TMAH), for A9M steel in industrial water (IW) was investigated using weight loss, potentiodynamic polarization and EIS measurement. The results showed that the inhibition efficiency of the TMAH increases with the increase of its concentration which acts as anodic inhibitor. The Characterizations that have been performed as the surface morphology by optical microscope, surface roughness and scanning electron microscopy (SEM) have proved that TMAH can exhibit good inhibition ability by forming a protective film on A9M steel surface. Molecular dynamics simulation were used to investigate the strength of the interactions between metal surface and the tested compound. The data obtained from theoretical and experimental studies were in reasonable agreement

Removal of heavy metals using different polymer matrixes as support for bacterial immobilisation

Great attention is focused on the microbial treatment of metal contaminated environments. Three bacterial strains, 1C2, 1ZP4 and EC30, belonging to genera Cupriavidus, Sphingobacterium and Alcaligenes, respectively, showing high tolerance to Zn and Cd, up to concentrations of 1000ppm, were isolated from a contaminated area in Northern Portugal. Their contribution to Zn and Cd removal from aqueous streams using immobilised alginate, pectate and a synthetic cross-linked polymer was assessed. In most cases, matrices with immobilised bacteria showed better metal removal than the non-inoculated material alone. For the immobilisation with all the polymers, 1C2 was the strain that increased the removal of Zn the most, whereas EC30 was the most promising for Cd removal, especially when combined with the synthetic polymer with up to a ca. 11-fold increase in metal removal when compared to the polymer alone. Removal of individual metals from binary mixtures showed that there was differential immobilisation. There was greater removal of Cd than Zn (removals up to 40% higher than those showed for Zn). The results show that metal contaminated environments constitute a reservoir of microorganisms resistant/tolerant to heavy metals that have the capacity to be exploited in bioremediation strategies.Capsule immobilisation of bacteria in the naturally occurring alginate and pectate and in a synthetic cross-linked polymer increased the Zn and Cd removal abilities from single and binary contaminated waters; the applications with the synthetic polymer were the most promising for Cd and Zn removal in single and binary mixtures