Modeling and performance evaluation of the eICIC/ABS in H-CRAN

International audienceIn this paper, we propose mathematical models to evaluate the performance of the interference remediation technique eICIC/ABS (enhanced Inter-Cell Interference Coordination / Almost Blank Sub-frame) in the context of Heterogeneous Cloud based Radio Access Networks (H-CRAN) architecture and 5G networks. The objective is to propose a dynamic resource management tool to ease decisions on the activation/deactivation of micro-cells as well as on the distributions of subframes among macro and micro cells. First, we propose a Markov chain based model that fits the behavior of the considered scheme and allows the analysis of the cell throughput according to traffic load, radio conditions and the distribution of available resources among macro and micro cells. Then, we propose an approximation model with a closed form formula. The two models are validated and evaluated in terms of accuracy and computation time. Numerical results are compared to matlab simulations that reproduce realistic radio conditions. Results show that both models are accurate. However, the closed form approximation is less complex and provides faster results

Etude des proprietes mecaniques des couches galvanisees par nanoindentation

Les revêtements industriels Fe-Zn constituent une large gamme des semi-produits de galvanisation en continu de tôles minces destinées à l’industrie de la carrosserie automobile. Ce revêtement, typiquement d’une épaisseur de l’ordre de 10 μm, résultant d’un traitement de post-galvanisation est constitué d’une phase êta, dzêta, delta et gamma (interface substrat/revêtement)

Caracterisation des proprietes mecaniques par nanoindentation d’un revêtement de zinc pour differentes epaisseurs de tôles galvanisees

La nano-indentation permet de connaître les propriétés mécaniques des surfaces ou des couches minces, en particulier leur dureté et leur module d'élasticité réduit. Ce travail porte sur la détermination des propriétés mécaniques d’un revêtement de Fer-zinc formé sur un substrat en acier de construction laminé à froid avec différentes épaisseurs de tôles. Ce revêtement, typiquement d’une épaisseur de l’ordre 10-20 μm résultant d’un traitement de galvanisation, est constitué des phases êta, dzêta, delta et gamma (interface substrat/revêtement). Les échantillons sont issus de tôles galvanisées dans les conditions d’Arcelor Mittal Annaba. Les essais de nano indentation ont été menés en mode continu à l’aide d’un appareil Nano-Indenter XP ©. L’avantage de ce mode (CSM), est de rendre possible la mesure du contact indenteur/échantillon et donc la dureté (H) et le module de Young (E) tout au long de la phase de pénétration. Seize empreintes ont été réalisées sur différentes épaisseurs de tôle (0.4mm ; 0.7mm; 1mm et 1.5mm), sur chacun des deux constituants (couche Fe-Zn et substrat) ; celles réalisées sur le substrat servant à valider l’approche inverse à établir pour déterminer le comportement du revêtement

Tribological behavior of Ti-6Al-4V and Ti-6Al-7Nb Alloys for Total Hip Prosthesis

The aim of the study is to evaluate the friction and wear behavior of high-strength alloys Ti-6Al-7Nb used in femoral stem and compare it with a Ti-6Al-4V alloy cylindrical bar corresponding to ISO 5832-3 part 3/01-07-199 standard. The tribological behavior was investigated by wear tests, using ball-on-disc and pin-on-disc tribometers. These tests consisted of measuring the weight loss and the friction coefficient of samples. The oscillating friction and wear tests have been carried out in ambient with oscillating tribotester in accordance with standards ISO 7148, ASTM G99-95a, and ASTM G133-95 under different conditions of normal loads (3, 6, and 10 N) and sliding speeds (1, 15, and 25 mm·s−1). As counter pairs, a 100Cr6 steel ball with 10 mm in diameter was used. Results show that the two alloys had similar friction and wear performance, although their grain structures and compositions are different. Occurrence of large frictional occurred, is probably caused by formation and periodic, localized fracture of a transfer layer. Higher friction with larger fluctuation and higher wear rate was observed at the higher siding speed. The Ti-6Al-4V wear mechanism transforms from ploughing and peeling off wear at low sliding speed to plastic deformation and adhesive wear

Tour de tailleaugmenté et facteurs de risque cardiovasculaire [Increased waist circumference and cardiovascular risk factors]

Introduction. Obesity evaluated by body mass index (BMI) is a recognized cardiovascular risk factor. Studies have shown that adipose tissue deposition in visceral level, reflected by increased waist circumference itself was a cardiometabolic risk factor. Objective. The relationship was studied between a high waist circumference and a cardiovascular risk. Material and Methods. A descriptive and analytical cross-sectional survey was conducted among 200 subjects in 2014 in Tebessa. The questionnaire allowed us to gather the following information: anthropometric measurements, dietary habits, physical activity, smoking, personal and family history ... Blood sample was realized to determine some biochemical parameters. Results. In this study, 60.5% of the subjects had a pathological waist, women were more affected than men (72.86% vs 31.67%, p <0.0001). This prevalence peaked between 47-66 years (p <0.0001). Pathological waist circumference was a predictor of cardiovascular disease (CVD), (RR = 1.71, P = 0.028). This study revealed that 16.53% of subjects with a pathologicalwaistlines had diabetes, 55.5% were hypertensive, 49% had hypertriglyceridemia, 46% low HDL, and 18 % high LDL. In normal weight subjects, 22% had pathological waistline. Conclusion. The prevalence of abdominal obesity is higher among patients consulting in private practice in Tébessa, this requires screening and awareness of people with pathological waistline

Tribological behavior of Ti-6Al-4V and Ti-6Al-7Nb Alloys for Total Hip Prosthesis

The aim of the study is to evaluate the friction and wear behavior of high-strength alloys Ti-6Al-7Nb used in femoral stem and compare it with a Ti-6Al-4V alloy cylindrical bar corresponding to ISO 5832-3 part 3/01-07-199 standard. The tribological behavior was investigated by wear tests, using ball-on-disc and pin-on-disc tribometers. These tests consisted of measuring the weight loss and the friction coefficient of samples. The oscillating friction and wear tests have been carried out in ambient with oscillating tribotester in accordance with standards ISO 7148, ASTM G99-95a, and ASTM G133-95 under different conditions of normal loads (3, 6, and 10 N) and sliding speeds (1, 15, and 25 mm·s−1). As counter pairs, a 100Cr6 steel ball with 10 mm in diameter was used. Results show that the two alloys had similar friction and wear performance, although their grain structures and compositions are different. Occurrence of large frictional occurred, is probably caused by formation and periodic, localized fracture of a transfer layer. Higher friction with larger fluctuation and higher wear rate was observed at the higher siding speed. The Ti-6Al-4V wear mechanism transforms from ploughing and peeling off wear at low sliding speed to plastic deformation and adhesive wear