Utilisation de la réponse diélectrique pour le diagnostic des transformateurs de puissance

Les transformateurs jouent un grand rôle pour assurer la continuité de la distribution de l'énergie électrique. La plupart d'entre eux ont été construits aux débuts des années 1960 et arrivent à la limite de la période pour laquelle ils ont été prévus, soit une cinquantaine d'années. Il est devenu nécessaire de pouvoir anticiper les défaillances par un diagnostic adéquat. Le papier du système d'isolation constitue le maillon faible d'un transformateur et connaître son état c'est connaître celui du transformateur. Il est difficile de prélever des échantillons de l'isolation. Par contre, on sait que la réponse diélectrique à un champ électrostatique dépend fortement des caractéristiques physiques du matériau. Ce mémoire porte sur l'utilisation de cette réponse pour le diagnostic des transformateurs de puissance. À partir de la réponse diélectrique de 8 maquettes qui constituent notre ensemble d'apprentissage, on a cherché dans un premier temps à trouver la relation existant entre le degré de polymérisation DP, indicateur de l'état du papier, et la réponse diélectrique. En second lieu, on s'est attelé à la tâche d'exprimer cette relation indépendamment des facteurs variables. Ensuite, on a utilisé la modélisation de l'interaction entre les constituants du transformateur pour en déduire la réponse diélectrique du papier. Finalement, la phase de validation a consisté à comparer les résultats obtenus par la modélisation avec les mesures effectuées sur les échantillons et à vérifier la linéarité en comparant les mesures fréquentielles avec la transformée de Fourier des mesures temporelles. Toutes les données expérimentales sont consignées dans une base de données relationnelle. La méthode utilisée pour ajuster les données expérimentales aux relations paramétriques fait appel à régression linéaire. Quand cela est nécessaire on utilise la régression non linéaire pour un ajustement plus précis. Les résultats obtenus montrent qu'en l'absence d'humidité excessive, il existe une relation entre la réponse diélectrique et l'état de l'isolation. La phase de validation montre que pour les cuves non humides, les hypothèses de linéarité sont légitimes

First volumetric records of airborne Cladosporium and Alternaria spores in the atmosphere of Al Khor (northern Qatar): a preliminary survey

Daily monitoring of airborne fungal spores was carried out for the first time in Al Khor city, Qatar, using a Hirst type 7-day recording volumetric spore trap, from May 2017 to May 2019. During the sampling period, the annual and monthly fluctuations, as well as intradiurnal variations of airborne fungal spore concentrations, were evaluated. Cladosporium, followed by Alternaria, were the spore types most abundant in the atmosphere of the city, with a strong interannual variability in the atmospheric concentrations being observed. The Annual Spore Integrals (ASIns) were 3334 and 1172 spore * day/m3 (2017–2018), and 6796 and 1538 spore * day/m3 (2018–2019) for Cladosporium and Alternaria, respectively. Total daily spore concentrations showed significantly positive correlations with mean, minimum, and maximum temperatures but significantly negative correlations with relative humidity. However, due to the scarce rainfalls’ days, we did not find a statistically significant correlations between Cladosporium and Alternaria spore concentrations and this parameter. Despite this, the spore peaks were strongly related to precipitations that occurred during the previous month. In general, no significant correlations were found with wind speed but, regarding wind direction, the higher percentage of spores were collected when wind blows from the 4th quadrant (NW). According to the intradiurnal pattern, Cladosporium fungal spores displayed their maximum daily concentration during 8:00–10:00 h in the morning, with a second peak in the afternoon, while for Alternaria, the maximum peaks were observed between 08:00 and 14:00 h. Because no consistent previous aerobiological studies exist from Qatar, the aim of this study is to define the seasonality and intradiurnal behaviour of these two airborne fungal spore and the role that, in such arid scene, the meteorological parameters play on the spore concentrations.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. Funding for open access charge: Universidad de Málaga / CBUA. We declare that the research reported in this manuscript received supported grant funding from the Qatar National Research Fund (QNRF)-Qatar (Project NPRP 9–241-3–043)

Massive spinal-ischial dysplasia and extensive spinal dyssygmentation in a Tunisian child with severe form of Cleido- cranial dysplasia

Abstract Kyphoscoliosis is a complication of some bone dysplasias, including Cleido-cranial dysplasia (CCD). We report on massive spinal dysplasia secondary to severe spinal dyssygmentation associated with marked defective ossification of the ischium, detected in a Tunisian female child with a severe form of Cleido-cranial dysplasia. Literature review on Cleido cranial dysplasia and associated spinal abnormalities showed no previous similar reports as encountered in our patient

Atlanto-axial rotatory fixation in a girl with Spondylocarpotarsal synostosis syndrome

We report a 15-year-old girl who presented with spinal malsegmentation, associated with other skeletal anomalies. The spinal malsegmentation was subsequently discovered to be part of the spondylocarpotarsal synostosis syndrome. In addition, a distinctive craniocervical malformation was identified, which included atlanto-axial rotatory fixation. The clinical and the radiographic findings are described, and we emphasise the importance of computerised tomography to characterize the craniocervical malformation complex. To the best of our knowledge, this is the first clinical report of a child with spondylocarpotarsal synostosis associated with atlanto-axial rotatory fixation

Giant primary adrenal hydatid cyst presenting with arterial hypertension: a case report and review of the literature

<p>Abstract</p> <p>Introduction</p> <p>A primary hydatid cyst of the adrenal gland is still an exceptional localization. The adrenal gland is an uncommon site even in Morocco, where echinococcal disease is endemic.</p> <p>Case presentation</p> <p>We report the case of a 64-year-old Moroccan man who presented with the unusual symptom of arterial hypertension associated with left flank pain. Computed tomography showed a cystic mass of his left adrenal gland with daughter cysts filing the lesion (Type III). Despite his negative serology tests, the diagnosis of a hydatid cyst was confirmed on surgical examination. Our patient underwent surgical excision of his left adrenal gland with normalization of blood pressure. No recurrence has occurred after 36 months of follow-up.</p> <p>Conclusion</p> <p>There are two remarkable characteristics of this case report; the first is the unusual location of the cyst, the second is the association of an adrenal hydatid cyst with arterial hypertension, which has rarely been reported in the literature.</p

A cost-effective approach for spectrum sensing using beamforming

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Blind Spectrum Sensing Using Extreme Eigenvalues for Cognitive Radio Networks

International audienc

Disorder of Sexual Development and Congenital Heart Defect in 47XYY: Clinical Disorder or Coincidence?

Background. 47XYY syndrome is a rare sex chromosome variation characterized by an additional Y chromosome. Most patients with 47XYY karyotype have normal phenotype. This disorder seems associated with a higher risk of developing behavioral and cognitive problems, tall stature, and infertility in adulthood. Sexual development disorder is a rare finding. We report a first case with an abnormal left coronary artery originating from the pulmonary artery in a 47XYY patient. Case. A one-month-old child was referred for ectopic testis and micropenis. Physical examination revealed facial dysmorphia, micropenis, and curvature of the penis with nonpalpable testis. Laboratory tests showed decreased total testosterone and anti-Mullerian hormone (AMH) levels. Blood karyotyping revealed a 47XYY chromosomal formula. At the age of 3 months, the patient developed dyspnea and tachycardia. Echocardiography revealed an anomalous left coronary artery from pulmonary artery with left ventricular dysfunction requiring surgical revascularization by direct reimplantation of the left coronary artery system. Our second case was a 3-year-old child referred for hypospadias with nonpalpable left testicle. Physical examination showed hypertelorism. Blood karyotyping revealed a 47XYY chromosomal formula. Conclusion. To our knowledge, this is the first case of 47XYY syndrome associated with this congenital heart malformation and a sexual development disorder

Familial vertebral segmentation defects, Sprengel anomaly, and omovertebral bone with variable expressivity

A 10-year-old boy was found to have an unusual presentation of the Sprengel anomaly, omovertebral bones, and segmentation defects of the vertebral column at the cervical, thoracic, and sacral level. In addition, he showed hypertelorism, downslanting palpebral fissures, ptosis, webbing, and hypoplasia of the thenar and hypothenar areas. He had moderate mental delay. In addition to the segmentation defects and omovertebral bones, radiological studies showed a small pelvis and 11 pairs of ribs. Some of the features were present in the mother, and minimal symptoms were present in the father. The parents were consanguineous. A paternal cousin had segmentation defects, omovertebral bones, and a Sprengel deformity as well, although with milder presentation than the proband. We were unable to find a similar combination of manifestations in literature. The familial occurrence is best compatible with autosomal dominant inheritance, showing wide variability of expression. It is possible that the more notable signs in the proband can be explained by homozygosity for the disorder. (c) 2005 Wiley-Liss, In