50 research outputs found
INFLUENCE DE LâACTIVITE COMMERCIALE SUR LâURBANISATION : CAS DE LA COMMUNE DE BIRKHADEM, ALGER
LâĂ©tude du commerce fait partie de lâĂ©tude des activitĂ©s tertiaires, qui sont Ă la fois cause et consĂ©quence de lâextension urbaine, puisque elles assurent lâanimation et le dynamisme de la vie urbaine. La chute de lâunion des rĂ©publiques soviĂ©tiques (URSS), et la vague de libĂ©ralisations du commerce dans la quasi-totalitĂ© des pays du monde, Ă partir du dĂ©but des annĂ©es quatre-vingt-dix du siĂšcle dernier, nâa pas Ă©pargnĂ© lâAlgĂ©rie qui, elle aussi est passĂ©e dâune Ă©conomie planifiĂ©e caractĂ©risĂ©e par le monopole de lâĂ©tat Ă celle du type libĂ©ral. Ainsi, le commerce Ă lâimportation, dĂ©tenu par quelques dizaines de sociĂ©tĂ© nationale, est cĂ©dĂ© au privĂ© qui a investi le marchĂ© par des milliers dâimportateurs. Lâexemple de la SONACOME, sociĂ©tĂ© dâĂ©tat qui dĂ©tenait le monopole sur lâimportation de la piĂšce dĂ©tachĂ©e et des vĂ©hicule Ă cĂ©dĂ© la place Ă plus de 2283 importateurs privĂ©s1. Ce bouleversement Ă©conomique a concernĂ© aussi le commerce de gros et de dĂ©tail qui, aprĂšs la disparition des sociĂ©tĂ©s dâĂ©tat, dĂ©tiennent actuellement la majoritĂ© de la population occupĂ©e. Ces occupĂ©es permanents et occasionnels travaillent dans des activitĂ©s commerciales lĂ©gales et enregistrĂ©s au niveau du centre national du registre de commerce (CNRC), mais, le plus grand nombre active dans le commerce de maniĂšre informelle. Dans les pages qui suivent nous essayons de voir lâampleur du commerce Ă Birkhadem, une commune dâAlger, et son impact sur le mode dâurbanisation
Assessment of microbiological indoor air quality in a public hospital in the city of Agadir, Morocco
Background and Purpose: Air is the greatest dissemination agency of pathogenic microbes, which cause significant problem in the indoor hospital environment, in particularly in terms of nosocomial infections. In this context, it is important to know the types of microorganisms present in suspension in an air sample to assess the initial situation and the effectiveness of corrective measures.
Materials and Methods: This study aimed to assessment of microbiological indoor air quality in a three hospital units: central resuscitation, neonatal resuscitation and operating room, using a passive sampling method.
Results: Findings of this study indicated that the central resuscitation recorded the highest bacterial counts population 3.33 102 CFU/m3. Total viable count of fungal was recorded high in neonatal resuscitation. This research showed that Staphylococcus non aureus and Staphylococcus aureus were the most predominant among isolated bacteria. The percentage was 70% -21% in central resuscitation and 79%-13% in operating room. In neonatal resuscitation Staphylococcus non aureus represent (29%) followed by Staphylococcus aureus (19%), Pseudomonas aeruginosa (17%) and Pasteurella pneumotropica (16%). Thus, the fungal genera identified in operating room were Penicillium 61%, Aspergillus niger (20%) and Candida glabrata (19%). In neonatal resuscitation, we found Penicillium 51%, Candida glabrata 25% and Aspergillus niger 20%. In central resuscitation, the most predominant fungi were Cladosporium (30%), Penicillium (28%) and Candida glabrata (13%).
Conclusions: Microorganisms isolated from indoor air constitute microbial reservoirs that may present a risk of infection for both patients and staff. In this light microbiological monitoring of the environment in health facilities is a topic that is part of the news of the prevention of nosocomial infections
Effet de la tempĂ©rature frittage sur le comportement mĂ©canique et tribologique de lâalliage TiNi poreux
La biocompatibilitĂ© des implants est une condition indispensable Ă leurs usages. Elle peut ĂȘtre dĂ©finie par la compatibilitĂ© entre un systĂšme technique et un systĂšme biologique. On distingue deux types de biocompatibilitĂ©, structurale et celle de surface. Elle est caractĂ©ristique de lâendommagement provoquĂ© par lâimplant sur les tissus. Cet endommagement est liĂ© aux propriĂ©tĂ©s mĂ©caniques de lâimplant et aux produits libĂ©rĂ©s par le frottement et par la corrosion qui se manifestent Ă lâinterface du biomatĂ©riau et des tissus environnants. Ces derniers peuvent ĂȘtre Ă lâorigine de nombreuses irritations. A cet effet lâobjectif de ce travail est lâĂ©tude de lâeffet de la tempĂ©rature de frittage sur le comportement mĂ©canique, Ă©lectrochimique et tribologique de lâalliage TiNi poreux
A prospective multi-country observational trial to compare the incidences of diabetic ketoacidosis in the month of Ramadan, the preceding month, and the following month (DKAR international)
Route guidance and routing algorithms in vehicular networks
Dans cette thĂšse, nous nous intĂ©ressons Ă deux types dâarchitectures dans les rĂ©seaux vĂ©hiculaires : les rĂ©seaux Ă infrastructure et les rĂ©seaux sans infrastructure. Lâobjectif de ce travail est de dĂ©finir des solutions amĂ©liorant la connectivitĂ© des passagers des vĂ©hicules dans des environnements Ă densitĂ© variable en points dâaccĂšs. Pour ceci, dans un premier temps, nous nous intĂ©ressons aux algorithmes de guidage routier (dont lâobjet est de guider un vĂ©hicule dâun point de dĂ©part vers un point dâarrivĂ©e) en prenant en compte les emplacements des points dâaccĂšs le long des routes. Notre premiĂšre contribution est de dĂ©finir un algorithme de guidage qui offre une connectivitĂ© supĂ©rieure au chemin par dĂ©faut (en gĂ©nĂ©ral le plus court chemin) tout en maintenant une distance parcourue raisonnable pour les passagers du vĂ©hicule. Nous nous intĂ©ressons Ă©galement Ă la minimisation du nombre de handovers afin dâamĂ©liorer la qualitĂ© de service du rĂ©seau. Nous avons Ă©valuĂ© notre algorithme en termes de distance couverte et du nombre de handovers, tout en sâassurant de garder une distance totale parcourue raisonnable. Nous avons Ă©tudiĂ© dans un deuxiĂšme temps lâimpact du choix de lâalgorithme du guidage routier sur les performances de la couche rĂ©seau, oĂč nous avons pris en compte deux types de protocoles de routage de donnĂ©es : rĂ©actif et proactif. Ensuite, nous avons Ă©tudiĂ© une problĂ©matique rĂ©currente dans les rĂ©seaux vĂ©hiculaires qui est le routage des donnĂ©es de vĂ©hicule Ă vĂ©hicule. Ceci est particuliĂšrement utile en absence dâune infrastructure disponible sur la route. Nous proposons une solution inter-couches («cross-layer») qui tire profit des caractĂ©ristiques des rĂ©seaux sans fil pour offrir un protocole de routage multi-sauts. Contrairement Ă la plupart des propositions de protocoles de routage, notre solution ne requiert pas un Ă©change de messages de signalisation entre les voisins, ce qui amĂ©liore les performances du rĂ©seau en termes de charge utile et efficacitĂ©, surtout pour un rĂ©seau Ă forte mobilitĂ© comme câest le cas pour des rĂ©seaux vĂ©hiculaires oĂč les voisins changent dâune seconde Ă une autre, rendant problĂ©matique la mise Ă jour des informations de chaque nĆud mobile sur son entourageIn this thesis, we focus on two types of architectures in vehicular networks: infrastructure networks and networks without infrastructure. The goal of this work is to define solutions to improve connectivity for passengers of vehicles in environments with variable density of access points. For this, we start by studying route guidance systems (whose purpose is to guide a vehicle from a starting point to a destination point), taking into account the locations of access points along roads. Our first contribution is to define a route guidance algorithm that offers superior connectivity compared to the default path (usually the shortest path) while maintaining a reasonable distance for passengers. We dealt also another issue which consists in minimizing the number of handovers to improve the quality of network service. We evaluated our algorithm in terms of covered distance and the number of handovers, while making sure to keep a reasonable traveled distance. After that, we studied the impact of the choice of route guidance algorithm in the performance of the network layer, where we took into account two types of routing protocols data: reactive and proactive. Next, we studied a recurrent problem in vehicular networks which is routing data from vehicle to vehicle. This is particularly useful in the absence of available infrastructure on the road. We propose a cross-layer architecture that takes advantage of the characteristics of wireless networks to design a multi-hops routing protocol. Unlike most proposals for routing protocols, our solution does not require an exchange of signaling messages between neighbors, and so improves network performance in terms of overhead and efficiency, especially for networks with high mobility such as vehicular networks, where neighbors change frequently, making it difficult to update information from each mobile node on its surrounding
Admissibility of singular switched systems: LMI formulation
International audienceThis paper concerns the stability and the stabilization of discrete-time singular switched systems. Sufficient conditions for a discrete-time singular switched system to be admissible are expressed in strict Linear Matrix Inequalities (LMIs) terms. Design of state feedback controllers are then proposed in strict LMIs. For more relaxation, slack variables are introduced. These results are extended to static output feedback controller design. Numerical example is given to illustrate the proposed methods
Novel bounded real lemma for discrete-time descriptor systems: Application to Hâ control design
International audienceThis paper concerns the bounded real lemma for discrete-time descriptor systems. A new formulation of the bounded real lemma for these systems is given. It extends the recent results presented in Zhang, Xia, and Shi (2008) and gives necessary and sufficient conditions in strict LMI (linear matrix inequality) which is more suitable for the control design than those presented in Zhang, Xia, and Shi (2008). An application to the Hâ control design is given. A numerical example is presented to show the applicability of our approach
Lâapport des petites agglomĂ©rations dans la croissance urbaine en AlgĂ©rie
The dynamic urban system in Algeria has been marked by the spectacular expansion of the big cities (over 100Â 000 inhabitants) in northern Algeria since independence and up to 1980. Nowadays, the urban growth is mainly profitable for medium and little cities (3Â 000 Ă 50Â 000 inhabitants).Today, the urbanization process witnessed another expansion that is of the development of the small centres which influenced the urban system in Algeria. During the last decade, strong growth has been observed mainly in the south and high hills of Algeria.Itâs through a quantitative operation of the different categories, and the graphic illustration that we shall try to put in evidence the importance of small settlements in the urbanization process
Admissibility and control of switched discrete-time singular systems
International audienceThis paper studies the admissibility of switched discrete-time singular systems. Sufficient conditions for this admissibility are derived in a form of a set of strict linear matrix inequalities. Design of both state feedback and static output feedback controllers is given. Numerical examples are presented to illustrate the proposed approaches
Further enhancement on robust H_inf control design for discrete-time singular systems
International audienceThis note deals with the robust Hâ control design for uncertain discrete-time singular systems. Necessary and sufficient conditions for the admissibility for these systems are formulated in strict linear matrix inequalities (LMIs) formulation. Then both state feedback and static output feedback controllers are studied and robust necessary and sufficient design conditions are expressed in terms of strict bilinear matrix inequalities (BMIs). Robust Hâ controllers are designed for uncertain singular systems including uncertainties on matrix E. LMI design conditions are also proposed. An illustrative example is provided to show the effectiveness of the proposed approach