Drill Bit Whirl Mitigation Analysis: An Under Actuated System Perspective

Abstrac

System Identification of Autonomous On and Off-Road Vehicles with Non-linear Model Predictive Control for Path Tracking

There is no question that autonomous vehicles and robots are going to have a profound impact on the society in the near future. A deep understanding of the systems is required in-order to design safe autonomous systems that are deployed among people. This thesis proposes a nonlinear data-driven system identification techniques to improve the physics-based models coupled with a nonlinear MPC for path tracking for the Warthog and ASV. This thesis also proposes a novel approach for a longitudinal controller. Domain knowledge was extensively used to generate a feature set for the machine learning algorithms to learn. During the experiment, it was found that for the Warthog dataset, it needed at least 103 seconds worth of data to outperform the physics-based model. No conclusion can be made regarding the generality of the model. The learned models, for both the Warthog and ASV, returned the physics-based model with the parameters identified, suggesting that there is a slight delay in the system that was not accounted for given the nominal values. The nonlinear MPCs were validated using the Gazebo and CARLA simulators. The MPC for the Warthog followed the predefined path with an average error of 8 cm, however, it struggled with sliding while turning. The MPC for the ASVs were tested using three different scenarios; highway exits and entrances, highway driving, and city driving. Both the lateral and the controller tracked the generated path within the safety margin, which is the lane width. However, it failed the city driving test, exceeding the cross-track error of 3 m

Paludisme d'importation à plasmodium falciparum chez la femme enceinte (à propos d'une observation)

Nous rapportons une observation de paludisme d'importation à Plasmodium falciparum chez une patiente au cours de la 26ème semaine d'aménorrhée. Parmi le millier de voyageuses impaludées chaque année en France, à partir d'une zone d'endémie, la femme enceinte non immune est plus susceptible et exprime volontiers des formes graves dont l'évolution peut être rapidement péjorative. Le placenta ne joue pas de rôle protecteur vis-à-vis du fœtus. Il est soumis au risque de mort fœtale in-utéro, de prématurité et d'hypotrophie à la naissance ainsi qu'un paludisme de type congénital-maladie. Seul un diagnostic précoce et rapide permet la mise en œuvre d'un traitement curatif urgent qui fait appel à la QUININE, la voie intra-veineuse est privilégiée. Quant à la chimioprophylaxie, elle ne peut recourir qu'à un nombre très limité de moléculesAMIENS-BU Santé (800212102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Clonal Lineage Analysis of Shigella flexneri Isolates Circulating in Ahvaz, Iran

Background: Shigellosis is a significant public health challenge particularly in developing countries, and the spread of antibiotic resistance genes through integron structures has become an important problem in the treatment of Shigellosis. The aim of this study was to investigate the genetic association of Shigella flexneri antibiotic resistant clones collected from Ahvaz between 2013 and 2015 by pulse field gel electrophoresis (PFGE) method. Methods: A total of 45 S. flexneri isolates, which were resistant to ampicillin and cotrimoxazole, were obtained from patients with Shigellosis referred to Ahvaz hospitals during 2013 - 2015. PCR was performed to evaluate the frequency of Sul1, int1, blaOXA, and int2 genes. In addition, pulse field gel electrophoresis method was used to investigate the genetic relationship between 40 S. flexneri isolates. Results: PCR results showed that the highest frequency was related to the sul1 gene with 80 (36 isolates) and the lowest frequency was related to class 2 integron with 15.5 (7 isolates); 31.11 (14 isolates) of the isolates were sul1 and int1. Also, 13.33 (6 isolates) had blaOXA and int1 genes, simultaneously. But none of the isolates had class 1 integrons and class 2 integrons at the same time. PFGE results showed 25 different pulsotype patterns, of which 16 isolates had their own unique pattern and were divided into 16 pulsotypes, and 27 isolates were divided into 9 pulsotypes. Conclusions: int2 and sul1 resistance genes had an upward trend from 2013 to 2015 and the results of PFGE indicated a different origin of S. flexneri clones