Caractérisation à grande échelle d'un signal 60 GHz dans un environnement minier confiné

Les télécommunications sans fil ont connu un grand intérêt et succès depuis plusieurs années grâce à leur facilité de déploiement par rapport aux télécommunications filaires, leur support de la mobilité des nœuds communiquant et leur souplesse d'utilisation par les usagers. Le problème actuel des télécommunications sans fil est de pouvoir assurer des débits élevés de transmission capable de supporter des applications fortement gourmande en bande passante. Pour relever ces défis plusieurs solutions sont proposées. Parmi elle la montée en fréquence vers le spectre des ondes millimétriques. Cette approche est à la base de notre étude qui porte un intérêt particulier à l'étude de la propagation d 'un signal 60 GHz dans un dans un milieu confiné en mettant en œuvre un sondeur de canal pour ses ondes millimétriques. Les résultats des mesures à grande échelle d'un signal à 60 GHZ sont étudiés dans plusieurs scénarios : visibilité directe, et en visibilité obstruée en utilisant comme obstacle un être humain, dans un environnement de laboratoire et dans un milieu souterrain minier. Les résultats montrent une différence considérable dans l'atténuation de canal pour ces différents scénarios. Ce travail a été effectué en partie au laboratoire de recherche en communications souterraine LRTCS à Val-d'Or, Canada et pour la partie expérimentation sous terre dans la mine de CANMET. Wireless communications have been a great interest and success for several years because of their infrastructure simplicity compared to wired telecommunications, their important terminal mobility, and also their flexibility of operation by users. The current problem of wireless telecommunications is being able to provide high transmission rates capable of supporting intensive applications consuming bandwidth. To meet these challenges, several solutions are proposed. Among them the rise in frequency to millimetre wave spectrum. This approach is the basis of our study that has a particular interest in the study of signal propagation in 60 GHz in a confined environment by implementing a channel sounder for its millimetre wave. The measurement results of a large-scale signal at 60 GHz are studied in several scenarios: Line of Sight and obstructed Line of sight using a human being as an obstacle in a laboratory environment and in an underground mining environment. The results show a considerable difference in the channel attenuation for these different scenarios. This work was done in part at the Underground Communications Research Laboratory LRTCS in Val-d'Or, Canada and the part of experimentation in underground CANMET mine

Evaluation of Pre-Analytical Variables in the Quantification of Dengue Virus by Real-Time Polymerase Chain Reaction

An accurate molecular diagnosis for viral pathogens is highly dependent on pre-analytical procedures. The efficiencies of two viral RNA extraction methods (liquid phase partition and silica-based adsorption chromatography) and the effects of handling and storage on the stability of RNA isolated from dengue virus (DENV) were studied. Viral RNA extracted from spiked sera or clinical samples characterized with DENV infection were quantified by TaqMan real-time PCR. The presence of high serum proteins severely affected the recovery of DENV RNA by the liquid phase partition, but not the silica-based method. The recovery with Trizol liquid phase partition method was significantly improved by a concomitant addition of a co-precipitant and the reduction of sera proteins, resulting in recoveries similar to that of the silica-based methods. Repeated freeze-thaw cycles did not affect the recovery of viral RNA. While intact DENV was found to be stable in serum for up to 2 hour at 25°C, recovery of viral RNA from sera stored in the lysis/binding buffer was stable for up to 5 days. These data indicate that the choice of viral RNA extraction methods, the conditions for handling, and storing of clinical sera critically affect the quantification of viral nucleic acid from clinical samples. This will impact the accuracy and reproducibility of DENV diagnosis by PCR-based assays