Yes / Voltage instability problems in power system are an important issue that should be taken into consideration during the planning and operation stages of modern power system networks. The system operators always need to know how far the power systems from voltage collapse in order to apply suitable action to avoid unexpected results. This paper propose a review of some static voltage stability indices found in the literature to study voltage collapse reveals that various analytical tools based on different concept to predict voltage collapse phenomena. These static voltage stability indices present reliable information about the closeness of the power system to voltage collapse and identification of the weakest bus, line and area in the power network. A number of static voltage stability indices have been proposed in the literature, but in this only four of them will be considered. The effectiveness of these indices is demonstrated through studies in IEEE 14 bus reliability test system. The results are discussed and key conclusion presented. / MSCRC

Introduction: La stratégie diagnostique de l’EP au cours de la grossesse est incertaine du fait du manque d’études solides d’un point de vue méthodologique, et du risque lié à l’irradiation des examens diagnostiques (angioscanner thoracique et scintigraphie pulmonaire). L’enjeu est donc de valider des stratégies performantes d’une part, et d’identifier des marqueurs cliniques permettant de réduire le recours aux examens irradiants d’autre part. Notre premier objectif a été d’identifier les pièges au cours de la stratégie diagnostique de l’EP (baisse de la performance du dosage des D‐dimères, des scores de probabilité clinique et de l’imagerie) au cours de la grossesse. Le deuxième objectif a été de comparer les performances diagnostiques et les risques des deux examens d’imagerie de référence que constituent la scintigraphie pulmonaire et l’angioscanner thoracique. Le troisième objectif a été de valider une stratégie diagnostique permettant une réduction du recours aux examens irradiants (ajustement du taux de D-dimères sur la probabilité clinique). Le dernier objectif a été de mettre en place un programme de recherche centré sur le poids des antécédents familiaux de MVTE, paramètre lui aussi susceptible de réduire le recours aux examens paracliniques. Conclusion : Au terme de ces analyses, nous avons développé un programme de validation d’une stratégie diagnostique de l’EP chez la femme enceinte ; en outre, l’identification d’un ajustement du taux de D‐dimères sur la probabilité clinique ainsi que, en termes de perspective, sur les antécédents familiaux de MVTE a le potentiel de conduire à des stratégies diagnostiques moins irradiantes et plus performantes chez les femmes enceintes ayant une suspicion d’EP. / Introduction : The diagnostic strategy for PE during pregnancy is uncertain due to the lack of high quality studies and the risk of radiation exposure with computed tomography pulmonary angiography (CTPA) and ventilationperfusion (V-Q) lung scan. The challenge is to validate diagnostic strategies, and to identify predictive factors to reduce the number of additional imaging tests with radiation exposure.First, we aim to identify pitfalls during the diagnostic strategy of PE (the D-dimer assay threshold, clinical probability scores, imaging) during pregnancy. Second, our objective was to compare the diagnostic efficiency of CTPA and (V-Q) lung scan during pregnancy.Third, our objective was to validate a diagnostic strategy wich reduces the number of imaging tests (adjustment of the D-dimer level on the clinical probability). Finally, the last objective was to set up a research program focused on the weight of the family history of MVTE, that may also reduce the need of additional tests. Conclusion : We identified an ongoing validation protocol with a new diagnostic algorithm in pregnant patients withPE suspicion ; Furthermore, identifying a D-dimer level adjustement as well as a family history of VTE can lead tomore effective diagnostic stragegies with less radiation exposure for pregnant women with suspected PE.

<p>Obstructive lung diseases limit airflow and gas exchange and have a major impact on a patient’s long-term health. Asthma and chronic obstructive pulmonary disease (COPD) are the most prevalent obstructive lung diseases and represent a major burden on healthcare systems worldwide. It is now accepted that the pathologies associated with these diseases are heterogeneous in nature, and as the function of the lung is determined by its three-dimensional structure, methods to volumetrically evaluate the lung are important tools in furthering the study of these pathologies.</p> <p>Three-dimensional imaging methodologies, such as computed tomography (CT) and single photon emission computed tomography (SPECT), are used clinically in the diagnosis of lung disease, but results are not commonly quantified. In addition, asthma and COPD develop slowly over time and diagnosis normally takes place after the underlying pathologies are well established. Experimental models in small animals, such as rats and mice, allow for the study of disease pathogenesis in a controlled setting and development of quantitative imaging practices for these models provides translational tools for relating results back to the clinic.</p> <p>In this thesis, CT densitometry and ventilation/perfusion (V/Q) SPECT are explored as methods to investigate models of asthma and COPD. CT densitometry is shown to be capable of quantifying allergic inflammation in an asthma model but is of less use in a model of COPD, predominantly due to the relative amounts of inflammation present. However, V/Q imaging is shown to be quite sensitive to the effects of cigarette smoke in a model of COPD and has been used to better understand how pathologies associated with COPD contribute to gas exchange limitation in the lung.</p> <p>The models, imaging techniques, and analysis methods described in this work provide insight into chronic obstructive lung disease and allow for future investigations into how pathologies effect gas exchange. Further, the characterization of the models described in this thesis allows for drug efficacy studies to be performed, both on established and novel treatments. Future research into asthma and COPD will benefit further from the use of threedimensional imaging methodologies because they provide volumetric information on structure and function and can act as a translational bridge between clinical disease and preclinical animal models.</p> / Doctor of Philosophy (Medical Science)