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Simulation of Space Charge Impact on Partial Discharge Inception Voltage in Power Busbars Dedicated to Future Hybrid Aircrafts

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Circuits and Systems 2018年第11期9卷 196-212页

作者： Mallys Elliazar Banda David Malec jean-pascal cambronne Laboratoire de Plasma et Conversion d’Energie Université de Toulouse-CNRS-INPT-UPS France

Reducing greenhouse gases, saving energy resources and mass optimization require technological changes towards increasingly electric vehicles. At the same time, performance improvement of semiconductor and dielectric materials further promotes electronic components confinement, resulting in a significant increase of embedded power densities. In the particular case of future hybrid propulsion aircrafts, electrical power that intended to supply reactors would be converted through power electronics components mounted on power busbars and insulated by solid dielectrics materials. These dielectrics materials have to respond to various electrical constraints of use (HVDC), in spite of environment change of aircraft parameters such as low pressure, temperature and thermal cycles, humidity... Unfortunately, partial discharges phenomenon is the most problem within electrical insulation system (EIS). Based on a topological model of power busbars designed for power converters dedicated to hybrid aircraft, partial discharge studies were conducted by simulation in various charging conditions of a PTFE insulator. Simulation results, which focus on electric field thresholds criteria of partial discharge inception voltage in air, reveal a net sensitivity of a space charge accumulation and distribution on dielectrics behaviour even for low space charge density, depending on their location in dielectrics. Compared to the behaviour observed with implanted homocharges, when by increasing homocharges density from 0.5 C/m3 to 2 C/m3 we observe a decrease of electric field by 450%, simulation results show a highest risk of partial discharge inception when heterocharges are accumulated inside dielectrics. Their accumulation increases the electric field in triple points beyond electric field thresholds of partial discharge inception in air. The simulated electric field reaching 22 kV/mm with only 2 C/m3 of heterocharges density accumulated in dielectric/busbars interfaces.

关键词： Simulation Partial Discharge Space Charge Power Busbars Hybrid Aircraft

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Modelling of the variation of granular base materials resilient modulus with material characteristics and humidity conditions

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Journal of Road Engineering 2024年第1期4卷 27-35页

作者： jean-pascal Bilodeau Erdrick Leandro Perez-Gonzalez Ali Saeidi Departement de Genie Civil et Genie des Eaux Universite LavalQuebecG1V 0A6Canada Departement des Sciences Appliquees Universite du Quebeca ChicoutimiChicoutimiG7H 2B1Canada

This study aims to quantify the susceptibility of granular materials used in pavements to changes in moisture content and propose a correlation model to incorporate this susceptibility into seasonal *** fines content and the percentage of fractured coarse aggregates were identified as direct indicators of the resilient modulus susceptibility to changes in water *** results showed that the percentage of fractured coarse aggregates particles(FR)has a more significant impact on the resilient modulus(Er)of crushed granular materials used in pavement construction than the combined indicator of the fines content and sample volumetrics(nf).Crushed granular materials with a higher percentage of fractured coarse aggregates are relatively insensitive to changes in the degree of saturation,but become more sensitive as the fine fraction porosity *** adjusted model was proposed based on the existing formulation,but considers a complex parameter to describe and adjust the sensitivity of base granular materials to variations in moisture content with respect to fabrication charac-teristics,fines content and volumetric *** model shows that the variation of Er values is below10%for fully crushed granular ***,it reaches approximately±12%for materials with 75%of crushed coarse aggregates andþ40%and-25%for materials with FR=50%.This model could help select good ag-gregates characteristics and adjust grain-size distribution for environments where significant moisture content variations can occur in the pavement system,such as in the Province of Quebec(Canada).As it is based on pa-rameters that can be easily determined or estimated,it also represents a valuable tool for detailed design and analysis that can consider material characteristics.

关键词： Resilient modulus Degree of saturation Humidity conditions Unbound granular materials Pavement base

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Environmental Assessment and Dielectric Performances of the Secondary Electrical Insulation in Low Voltage Motors Impregnated by Different Techniques

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Engineering（科研） 2017年第10期9卷 860-873页

作者： Manh Quan Nguyen Simon Dario David Malec Dominique Mary jean-pascal cambronne Damien Prunel Julie Orgelet LAPLACE Université de Toulouse CNRS INPT UPS Toulouse France Bureau Véritas Moirans France

A recent technique, using to potentially replace the conventional impregnating one in low voltage electric motors, has been studied in this communication. The conventional technique that uses?both primary and secondary insulations;?i.e.: enamel and varnish, has been compared to this recent technique which only uses one component,?i.e.: self-bonding wires. Self-bonding wires polymerization is very quick compared to that of the conventional technique. Environmental impact and both dielectric and mechanical properties of these two techniques have been estimated and compared. The goal is to estimate if this recent technique has not only a better environmental footprint but also good technical properties. The dielectric properties that have been measured are the dielectric strength and?the lifetime under pulse?voltage while mechanical consists in measuring the bonding strength that is crucial for impregnation.?For that purpose, a Life Cycle Assessment (LCA) that can simultaneously evaluatenumerous impacts on ground, water and air,?has been performed. The results show clearly that the recent technique significantly reduces the environmental footprint. Both mechanical and dielectric properties are then compared and analyzed.

关键词： Electrical Motor Enameled Wire Self-Bonding Wire Impregnation Tech-nique Dielectric Performance Environmental Impact

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Massive abdominal muscle atrophy during prolonged mechanical ventilation: Implications for tracheostomy removal

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Journal of Intensive Medicine 2024年第1期4卷 133-135页

作者： pascal Beuret Florian Michelin Audrey Tientcheu Laurane Chalvet Benedicte Philippon-Jouve jean-Charles Chakarian Xavier Fabre Service de Réanimation et Soins continus Centre Hospitalier de RoanneRoanneFrance

Introduction Maintaining the functional integrity of respiratory muscles is crucial for critically ill patients to be weaned from mechanical ventilation and decannulated if *** of the diaphragm is frequent in patients under mechanical ventilation and has been associated with a longer duration of weaning.[1,2]Studies on expiratory muscles are *** recent studies demonstrated the feasibility and reproducibility of ultrasound in measuring the thickness of abdominal muscles,[3,4]with one study showing abdominal muscle atrophy in 22%of mechanically ventilated critically ill patients during the first week of mechanical ventilation.[4]

关键词： critically mechanical abdominal

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Postoperative Analgesia and Cesarean Section under General Anesthesia: Multicenter Study

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Open Journal of Anesthesiology 2024年第1期14卷 1-12页

作者： Ghislain Edjo Nkilly Raphael Okoue Ondo pascal Christian Nze Obiang Stéphane Oliveira jean-Marcel Mandji-Lawson Romain Tchoua Department of Anesthesia and Intensive Care Omar Bongo Ondimba Army Training Hospital (HIAOBO) Libreville Gabon Department of Anesthesia and Intensive Care Jeanne Ebori Fondation Libreville Gabon Department of Anesthesia and Intensive Care Akanda Army Training Hospital Libreville Gabon

Background: Neuraxial anesthesia with intrathecal morphine is the reference technique in cesarean section anesthesia for the management of postoperative analgesia. If there is a contraindication to this, general anesthesia is required. The objective of the study was to evaluate the analgesic effectiveness of 4 analgesic techniques performed during cesarean section under general anesthesia in two centers with different anesthetic practices (North Franche Comté Hospital and Omar Bongo Ondimba Army Training Hospital). Method: This is a retrospective and descriptive study over 2 years, from January 1, 2019 to December 31, 2020. It involved evaluating the analgesic effectiveness and tolerance of morphine in the epidural catheter, wound infiltration, intravenous analgesia and Transversus Abdominous Plane block (TAP block) from the post-anesthesia care unit (PACU) until the 4th post-operative day. Results: Of the 354 cesarean sections performed, 84 (11.14%) received general anesthesia. The average age was 32.27 years. Acute fetal distress was the first indication for cesarean section (45.2%), followed by hemorrhagic placenta previa (10.7%) and prolapse of the cord (8.33%). Morphine in the epidural catheter was the most used (47.6%) followed by parietal infiltration (36.9%), intravenous analgesia (13.1%) and TAP block (2.38%). The analgesic effectiveness was comparable between the techniques from postoperative day 0 to day 4. No difference in side effects. Postoperative morphine consumption was significantly reduced (p = 0.011) in the infiltration (9 mg) and TAP block (9mg) groups compared to the epidural catheter (16 mg) and intravenous analgesia (17 mg). No difference in 02 rehabilitation criteria (ambulation, first bowel movement). No difference in the occurrence of chronic pain. Conclusion: In the event of a cesarean section under general anesthesia, there are effective and well-tolerated alternatives to neuraxial anesthesia, particularly regional anesthesia

关键词： Cesarean General Anesthesia Morphine Parietal Infiltration Epidural Catheter Transversus Abdominis Plane Block Intravenous Analgesia

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Modelling the viscoplastic behaviour of Callovo-Oxfordian claystone with consideration of damage effect

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第1期16卷 303-316页

作者： Hao Wang Yu-Jun Cui Minh Ngoc Vu jean Talandier Ecole des Ponts ParisTech Laboratoire Navier/CERMES6 et 8 avenue Blaise PascalMarne La Vallée cedex 277455France Andra R&D DepartmentChâtenay-Malabry92290France

In order to evaluate the performance of deep geological disposal of radioactive waste,an underground research laboratory(URL)was constructed by Andra in the Callovo-Oxfordian(COx)claystone formation at the Meuse/Haute-Marne(MHM).The construction of URL induced the excavation damage of host formations,and the ventilation in the galleries desaturated the host formation close to the gallery ***,it is expected that the mechanical behaviour of COx claystone is *** study presents a constitutive model developed to describe the viscoplastic behaviour of unsaturated and damaged COx *** this model,the unsaturation effect is considered by adopting the Bishop effective stress and the van Genuchten(VG)water retention *** terms of the viscoplastic behaviour,the nonstationary flow surface(NSFS)theory for unsaturated soils is used with consideration of the coupled effects of strain rate and suction on the yield stress.A progressive hardening law is ***,a non-associated flow rule is used,which is similar to that in Barcelona basic model(BBM).In addition,to describe the damage effect induced by suction change and viscoplastic loading,a damage function is defined based on the crack volume *** damage function contains two variables:unsaturated effective stress and viscoplastic volumetric strain,with the related parameters determined based on the mercury intrusion porosimetry(MIP)*** the model validation,different tests on COx claystone under different loading paths are *** between experimental and simulated results indicated that the present model is able to well describe the viscoplastic behaviour of damaged COx claystone,including swelling/shrinkage,triaxial extension and compression,and triaxial creep.

关键词： Callovo-Oxfordian(COx)claystone Excavation damage Time-dependent behaviour Suction Viscoplastic model

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Intermediate Hip Arthroplasty in Gabon: Blood Loss and Risk Factor for Transfusion

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Open Journal of Anesthesiology 2024年第4期14卷 109-117页

作者： Ghislain Edjo Nkilly pascal Christian Nze Obiang Raphael Okoue Ondo Arthur Matsanga Stéphane Oliveira Léandre Nguiabanda jean-Marcel Mandji-Lawson Department of Anaesthesia and Intensive Care Omar Bongo Ondimba Army Training Hospital (HIAOBO) Libreville Gabon Department of Anaesthesia and Intensive Care Jeanne Ebori Fondation Libreville Gabon Department of Anaesthesia and Intensive Care Owendo University Hospital (CHUO) Libreville Gabon Department of Anaesthesia and Intensive Care Akanda Army Training Hospital Libreville Gabon Orthopedic Surgery Service Omar Bongo Ondimba Army Training Hospital (HIAOBO) Libreville Gabon

Background: Hip arthroplasty is a surgery with a high risk of bleeding. The main objective of this study was to research risk factors for bleeding and transfusion in patients undergoing hip hemiarthroplasty in Gabon. Method: It was a retrospective, monocentric, descriptive and analytical study carried out from June 2011 to June 2021 at the Omar Bongo Ondimba army training hospital. The variables studied were demographic characteristics, biological variables, transfusion and intraoperative data. The primary outcome was intraoperative transfusion. A univariate and multivariate analysis was conducted to identify the factors associated with the occurrence of a transfusion. Results: Of the 97 patients included, the average age was 74.2 years ± 10, male predominance was 73.2%, the average ASA score was 1.9 ± 0.5, and transfusion incidence was 38.1%. The average number of RBCs transfused was 1.2 ± 0.6. Tranexamic acid was used in 11.3% of patients. The average bleeding was 450 ± 453 ml. Preoperative anemia was predictor of transfusion to be significant. Conclusion: The incidence of transfusion is law compared to total hip arthroplasty. The implementation of a patient blood management protocol is difficult given the urgency of bone repair. However, a better use of tranexamic acid could reduce this transfusion incidence.

关键词： Hip Arthroplasty Risk Factors Patients Hemiarthroplasty Gabon

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Late Diagnosis of Turner Syndrome in Adulthood;a Case Study from the Endocrinology-Diabetology Nutrition Department of the National Hospital of Pikine Senegal

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Open Journal of Endocrine and Metabolic Diseases 2024年第5期14卷 115-122页

作者： Nafy Ndiaye Yakham Mohamed Leye Ngone Diaba Diack Mamadou Ba Bibatou Abdoulaye Leye Abdou Aziz Diouf Alassane Diouf jean pascal Demba Diop Internal Medicine/Endocrinology-Diabetology Department Teaching Hospital of Pikine Cheikh Anta Diop University Dakar Senegal Department of Gynaecology-Obstetric Teaching Hospital of Pikine Cheikh Anta Diop University Dakar Senegal Department of Human Genetic Faculty of Medicine Pharmacy and Odontology Cheikh Anta Diop University Dakar Senegal

Introduction: Turner syndrome is a rare genetic disorder characterised by the presence of one X chromosome and the absence of part or all of an X or Y chromosome and patients may experience delayed puberty and infertility. Our study aimed to evaluate the diagnostic delay in our practice and analyze the impact of this diagnostic delay on the effectiveness of patient management. Patients and Methods: Turner syndrome patients were identified from the endocrinology-diabetology nutrition department Database We examined the records of patients in whom the karyotype analysis favoured Turner syndrome. Results: We have selected 5 patients’ records of female patients with Turner syndrome. The mean age was 25, ranging from 19 to 29 years. Primary amenorrhea and characteristic dysmorphic features were observed in all patients. One married patient, who sought consultation for infertility, expressed a desire for pregnancy. Short stature was identified in 3 patients. Primary hypothyroidism and hypertension were respectively found in 1 and 2 patients. Gonadal dysgenesis was noted in 100% of cases. Karyotype analysis revealed monosomy X in 2 patients and mosaic patterns in others. All patients received estrogen-progestin treatment. Antihypertensive therapy was initiated for 2 patients. One patient is on L-thyroxine. In the short term, treatment led to the onset of menstruation after the initial months. Evaluation of treatment efficacy on internal genital organs is yet to be performed. Due to uncertain benefits at this age, growth hormone therapy was not considered for our patients. We provided counseling on assisted reproductive options for couples desiring to conceive. In our study, all patients were placed on estrogen-progestin therapy, and the response appeared favorable. Conclusion: In our practice, the diagnosis of Turner syndrome occurs very late in adulthood, at an age when growth hormone treatment is nearly ineffective. Treatment typically revolves around estrogen-progestin

关键词： Turner Syndrome Primary Amenorrhea Adult Pikine

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Phytochemical Screening, Study of Acute Toxicity and Hypoglycemic and Antihyperglycemic Activities of Silver Nanoparticles from Guibourtia tessmannii (Harms) J. Leonard (Caesalpiniaceae)

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Open Journal of Applied Sciences 2024年第1期14卷 118-130页

作者： Ngoulé Charles Christian Eya’ane Meva François Sone Enone Bertin Ngo Nyobe Biwole Caroline Tankeu Séverin Elisée Songue pascal Nguene jean Pierre Etame-Loe Gisèle Department of Pharmaceutical Sciences Faculty of Medicine and Pharmaceutical Sciences University of Douala Douala Cameroon Department of Biology of Plant Organisms Faculty of Sciences University of Douala Douala Cameroon

According to the World Health Organization, diabetes affects approximately 347 million people worldwide. Its management is not within the reach of all social classes, therefore medicinal plants are still the first resort for many populations in Africa. The biological material used in this study was the trunk bark of Guibourtia tessmannii. 50 g of trunk bark powder were decocted in 500 ml of distilled water for 5 minutes were carried out. The method used for the synthesis of silver nanoparticles (AgNps) was an organometallic bio-reduction of silver nitrate salts mediated by various secondary metabolites contained in the plant extract. The study of the toxicity acute was conducted according to guideline 423 of the OECD protocol. The pharmacological activities were each carried out with 28 female rats divided into 7 groups of four rats. It was a question for the hypoglycemic activity of administering various doses of silver nanoparticles and other substances to the rats thirty minutes after the carbohydrate intake and for the anti-hyperglycemic activity of administering the same substances to the rats thirty minutes before the carbohydrate intake. The extraction yield was 8.76%. Only the alkaloid test was negative. After acute toxicity study, the LD50 was greater than 2000 mg/kg. Blood sugar tests revealed that glibenclamide 5 mg/kg, which is the reference molecule, lowered blood sugar more than the other treatments applied in the other batches. It was followed by treatment with silver nanoparticles at a dose of 400 μg/kg in both tests. It was therefore concluded that silver nanoparticles from G. tessmannii are good for the formulation of improved traditional medicines and bring up their afficacity .

关键词： Guibourtia tessmannii Nanoparticles Hypoglycemia Anti-Hyperglycemia

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End-of-Pregnancy Monitoring at CHUMEFJE through the Functional Investigation Centre (FIC) in 2022

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Open Journal of Obstetrics and Gynecology 2024年第1期14卷 186-192页

作者： Ulysse pascal Minkobame Zaga Minko Opheelia Makoyo Komba Pamphile Assoumou Obiang Anouchka Mewie Lendzinga Elsy Ntsame Mezui Irenee Edzo Mvono Jacques Albert Bang Ntamack jean François Meye Department of Obstetrics and Gynaecology University of Health Sciences Libreville Gabon

Introduction: The end of pregnancy is a high-risk period for both mother and foetus. Rigorous monitoring can prevent complications before delivery. Materials and Method: We conducted a descriptive cross-sectional observational study. It took place in the delivery room of the Teacher hospital Mother and Child of jeanne Ebori Fondation from the 01 October 2020 to 01 October 2021. All patients followed at the Functional Investigation Centre (FIC) of the CHUMEFJE and who gave birth in that same hospital were included. Data were collected on the basis of pregnancy diaries, the fic register and delivery room registers. They were analysed using SPSS Statistical Software. Results: During the period of our study, 4086 parturients arrived in the delivery room. Of these, 150 were followed up at the FIC, giving a prevalence of 3.7%. The majority of parturients (48%) had only one prenatal contact. 6 (4%) patients underwent pelvic scans, and 4 (2.6%) presented with a narrowed pelvis. A vaginal delivery was performed in 80% of cases, and of the caesarean sections, 9 (30%) could be scheduled. The maternal prognosis was marred by one post-partum complication of hypertension, and newborns with poor adaptation to life outside the womb accounted for 3.3% of cases. Conclusion: The Functional Investigation Centre makes it possible to detect anomalies at the end of pregnancy with a view to better planning of delivery.

关键词： Follow-Up End of Pregnancy Scheduled Caesarean Section Prognosis

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