Electric Driven Centrifugal Compressor - Super Synchronous Vibrations of the High Speed Shaft Line: Observations, Assessment and Resolution

LectureAn unacceptable vibratory behavior was encountered in 2012 during the full load string test of an electric driven centrifugal compressor. The vibrations were observed on the high speed part of the shaft line and both compressor and gearbox exhibited vibratory levels higher than 50 microns peak to peak on the second harmonic (H2) of the rotational speed. The centrifugal compressor is driven via a variable speed electrical motor through a gearbox. The main characteristics of the shaft line are the following: 9 MW electrical motor running from 1250 to 1875 rpm to cover the whole operating speed range of the compressor; Gearbox with a speed ratio of 7.035; Centrifugal compressor (back to back arrangement) from 72 to 167 bara (first stage) and from 165 to 307 bara (second stage); Low speed and high speed flexible couplings of membrane type technology. All individual components of the train were successfully tested prior to be integrated to constitute the complete shaft line package. The aerodynamics performances of the compressor were as expected, and the gear box and the compressor did not exhibit any abnormal vibratory behavior. During the ASME PTC10 Type 1 string test of the complete package, super-synchronous vibrations were detected on the compressor and the pinion of the gearbox while the compressor was running at around 94% speed. Extensive theoretical and experimental investigations were conducted to identify the root cause of the 2X vibration component with the full involvement of the different components suppliers: Potential excitation coming from the electrical drive system; Potential excitation coming from the gearbox; Aerodynamic excitation coming from the compressor; Torsional resonance and/or interaction with lateral behavior; Contact, alignment, lubrication influence, type of bearings; Lateral critical speed combination (train shaft line analysis); Type of coupling, non linearity and lack of flexibility. The issue was solved within three months thanks to the following modifications: Gearbox bearing span increase and reduction of the overhang, by modifying the existing pinion design; New coupling with reduced moment. The paper will describe the investigations that were conducted to understand the root cause of the supersynchronous vibrations as well as the modifications that have been successfully implemented

Argiles et zéolites dans l'altération d'un volcan bouclier en milieu tropical (Le Piton des Neiges, La Réunion)

International audienceThe drilling of a gallery through the Roche-Écrite massif (Reunion Island) allowed to sample the old formations of the ‘Piton des Neiges’ volcano. The mineralogical study of the alteration products of the formations showed significant variations of the zeolites/clay minerals ratio depending on the location of the rocks in the volcano. The abundance of zeolites in the formation near the surface hydrographic network or the underground water drainage system seems to be due to the physicochemical processes favouring zeolites in more open systems in their competition with secondary clays. To cite this article: L. Bret et al., C. R. Geoscience 335 (2003).Le creusement d'une galerie profonde à travers le massif de la Roche-Écrite (ı̂le de La Réunion) a permis d'échantillonner les formations anciennes du volcan du Piton des Neiges. L'étude des minéraux d'altération de ces formations fait apparaı̂tre d'importantes variations des proportions zéolites/argiles selon leur situation au sein de ce volcan. La forte représentation des zéolites dans les formations bordant les réseaux hydrographiques ou les réseaux de drainage de l'eau souterraine semble due à un processus physicochimique favorisant, en système plus ouvert, la cristallisation des zéolites dans leur compétition avec les argiles secondaires. Pour citer cet article : L. Bret et al., C. R. Geoscience 335 (2003)

Asynchronous Motor - Failure of Rotor Lamination Teeth

Case StudyDuring full load testing of moto-compressor, abnormal vibration were detected. Failure was observed on electrical motor rotor lamination teeth. Deep experimental analysis and metallurgical investigations revealed a high cycle fatigue to be the root cause of the failure. Theoretical and experimental analyses involving modal analysis, electro-magnetic simulation, static and dynamic response and fatigue evaluation were performed. Issue resolution is based on the rotor lamination teeth geometrical modification and rotor/stator teeth ratio optimization. This case study describes the root cause analysis from theoretical to experimental perspectives

Combination of real-time needle-tip pressure sensing and minimal intensity stimulation limits unintentional intraneural injection during an ultrasound-guided peripheral nerve block procedure: A randomized, parallel group, controlled trial

International audienceStudy objective: Ultrasound guidance does not eliminate the risk of intraneural injection, which must be avoided during PNB. Combining ultrasound guidance (USG), nerve stimulation (NS), and injection pressure monitoring is advocated to prevent nerve injury during PNB. We hypothesized that combining patient-tailored dynamic NS and real-time pressure sensing (RTPS) could reduce the incidence of intraneural injection and nerve puncture during USG PNB compared with a traditional fixed thresholds (Control) procedure.Design: Randomized, prospective study.Setting: Operating room.Patients: One hundred ASA physical status I to III patients undergoing orthopedic surgery.Interventions: Patient anesthetized using axillary, sciatic or femoral USG PNB were randomized to the PresStim group (Dynamic RTPS and NS set at 1.5 mA then decreased; n = 50) or Control group (fixed thresholds for in-line pressure mechanical manometer and NS at 0.2 mA; n = 50).Measurements: Procedural ultrasound images and videos were recorded, stored and reviewed in random order by two experts in ultrasound-guided PNB blinded to the group. They noted the needle-to-nerve relationship and intraneural injection for all blocked nerves.Main results: One hundred and twenty-three USG PNBs were performed (56 axillary brachial plexus blocks, 40 femoral nerve blocks and 27 sciatic popliteal nerve blocks); 235 blocked nerves and videos were recorded and analyzed (PresStim, 118; Control, 117). Less paresthesia was noted in the PresStim group (12.7%) compared with the Control group (18.8%). The risk of intraneural injection was significantly higher in the Control group (odds ratio [OR], 17.1; 95% confidence interval [CI], 2.2-135, P = 0.007). The risk of nerve puncture (OR, 22.7; 95% CI, 2.9-175, p = 0.003) and needle-nerve contact (OR, 4.7; 95% CI, 2.4-9.5, p < 0.001) was significantly higher in the Control group than the PresStim group.Conclusions: Under the conditions of the study, dynamic triple monitoring combining RTPS, NS and USG decreases intraneural injection and unintentional needle-nerve contact and puncture during a PNB procedure

Real-Time Injection Pressure Sensing and Minimal Intensity Stimulation Combination During Ultrasound-Guided Peripheral Nerve Blocks: An Exploratory Observational Trial

International audienceBackground: Nerve damage can occur after peripheral nerve block (PNB). Ultrasound guidance does not eliminate the risk of intraneural injection or nerve injury. Combining nerve stimulation and injection pressure (IP) monitoring with ultrasound guidance has been suggested to optimize needle tip location in PNB. In this prospective observational study, we hypothesized that measured pairs of IP and minimum intensity of stimulation (MIS) might differentiate successive needle tip locations established by high-resolution ultrasound during PNB.Methods: For this exploratory study, 240 observations for 40 ultrasound-guided PNBs were studied in 28 patients scheduled for orthopedic surgery. During the progression of the needle to the nerve observed by ultrasonography, the IP was measured continuously using a computerized pressure-sensing device with a low flow rate of solution. Stimulation thresholds and electrical impedance were obtained by an impedance analyzer coupled to the nerve stimulator at 6 successive needle positions. The median (quartile) or mean (95% confidence interval [CI]) was reported. A mixed model analysis was used, and the sample was also explored using a classification and regression tree (CART) algorithm.Results: Specific combinations of IP and MIS were measured for subcutaneous, epimysium contact, intramuscular, nerve contact (231 mm Hg [203-259 mm Hg] and 1.70 mA [1.38-2.02 mA]), intraneural location (188 mm Hg [152-224 mm Hg] and 0.58 mA [0.46-0.70 mA]), and subparaneural location (47 mm Hg [41-53 mm Hg] and 1.35 mA [1.09-1.61 mA]). The CART algorithm shows that the optimal subparaneural needle tip position might be defined by the lowest pressure (<81.3 mm Hg) and MIS (<1.5 mA) cutoffs.Conclusions: Our exploratory study evaluated concepts to generate hypotheses. The combinations of IP and MIS might help the physician during a PNB procedure. A low IP and low MIS might confirm a subparaneural location, and a high IP and a low MIS might be an alert for the intraneural location of the needle tip.Trial registration: ClinicalTrials.gov NCT03430453

P570 : Exploration moléculaire des gènes CYP24A1, SLC34A1 et SLC34A3 dans une cohorte de patients avechypersensibilité à la vitamine D

International audienceIntroduction : L’hypersensibilité à la vitamine D correspond sur le plan biologique à l’association d’une hypercalcémie transitoireavec PTH basse (adaptée), d’une hypercalciurie et d’une 1,25-(OH)2D (calcitriol) augmentée (inappropriée).En dehors des formes néonatales transitoires, des formes génétiques récessives autosomiques (MIM143880, 616963) ont étédécrites, associées à des mutation perte de fonction de CYP24A1 (20q13.2, MIM126065), le gène codant l’enzyme vitamine D24-hydroxylase responsable du catabolisme de la vitamine D. Le déficit enzymatique est responsable d’une accumulation devitamine D active, d’où une dérégulation de l’absorption intestinale de calcium avec tendance à l’hypercalcémie/hypercalciuriechronique. En cas de prise de vitamine D ou d’exposition solaire (favorisant la synthèse cutanée de vitamine D), unedécompensation est possible sous la forme de complications aigües de l’hypercalcémie (désydratation, difficultés alimentaires,troubles du rythme et de la conduction) ou chroniques de l’hypercalciurie (lithiase rénale, néphrocalcinose, insuffisance rénalechronique).Plus récemment, un autre mécanisme physiopathologique a été identifié chez des patients présentant un phénotype similaireassocié à des anomalies du phosphate (hypophosphatémie et hyperphosphaturie modérées transitoires). Il s’agit de mutationsperte de fonction dans les gènes SLC34A1 (5q35.3, MIM182309) et SLC34A3 (9q34.3, MIM609826) codant les cotransporteurs sodium-phosphate NPT2a/NaPiIIa et NPT2c/NaPiIIc. Ces mutations ont précédemment été associées aurachitisme hypophosphatémique avec hypercalciurie (MIM612286, 241530).Elles sont responsables d’une fuite urinaire de phosphate, d’où une diminution de la sécrétion de FGF23, hormonehyperphosphaturiante inhibant la synthèse de calcitriol, et une dérégulation de la production de calcitriol.Matériel et méthode : Nous rapportons l’étude des régions codantes et des jonctions introns-exons par séquençage haut-débit(Ion Personal Genome Machine, Thermofisher Scientific, Waltham, Massachusetts, États-Unis) des gènes CYP24A1, SLC34A1et SLC34A3 dans une cohorte de 90 patients porteurs d’un phénotype d’hypersensibilité à la vitamine D.Résultats : Nous identifions 22 (24.4%) patients avec mutation biallélique de CYP24A1, 2 (2.2%) patients avec mutationbiallélique de SLC34A1 et 3 (3.3%) patients avec mutation biallélique de SLC34A3. Le phénotype biologique est identique àl’exception de phosphatémies fréquemment rapportées à la limite inférieure de la normale.Conclusion : Nous confirmons l’implication des gènes codant les transporteurs de phosphates NPT2a/NaPiIIa et NPT2c/NaPiIIcdans le phénotype d’hypersensibilité à la vitamine D, en moidre proportion que les mutation de CYP24A1. S’agissantessentiellement de mutations faux-sens, une étude attentive du phénotype, et en particulier du bilan phosphocalcique sanguinet urinaire, est nécessaire pour l’interprétation des variants

Émancipation et formation de soi Tome 1

La recherche en éducation se trouve à une croisée des chemins. La promotion de modèles en apparence horizontaux de formation de soi, prétendant échapper à une logique institutionnelle de l’autorité par la préparation à l’acquiescement politique direct, est favorisée par la montée en puissance des réseaux sociaux court-circuitant les voies classiques de l’information et par la croissance sans retenue des relations de coaching supposées apporter aux sujets une puissance d’agir inédite. Mais cette promotion ne « libère » en réalité que de sombres forces de domination contre lesquelles la pensée tente actuellement de s’armer. Les articles réunis dans ces deux numéros attestent qu’il est plus que jamais nécessaire d’articuler ensemble l’émancipation à la formation de soi, comme son seul horizon légitime, renouant ainsi avec ce qui constitue le projet inaugural de l’éducation. On trouvera ici, dans des thématiques convergentes, reprise et redéployée comme arme, la question d’une égalité que l’on se donne, contre une identité que l’on reçoit

Tracing Arab-Islamic Inheritance in Madagascar: Study of the Y-chromosome and Mitochondrial DNA in the Antemoro

International audienceMadagascar is located at the crossroads of the Asian and African worlds and is therefore of particular interest for studies on human population migration. Within the large human diversity of the Great Island, we focused our study on a particular ethnic group, the Antemoro. Their culture presents an important Arab-Islamic influence, but the question of an Arab biological inheritance remains unresolved. We analyzed paternal (n=129) and maternal (n=135) lineages of this ethnic group. Although the majority of Antemoro genetic ancestry comes from sub-Saharan African and Southeast Asian gene pools, we observed in their paternal lineages two specific haplogroups (J1 and T1) linked to Middle Eastern origins. This inheritance was restricted to some Antemoro sub-groups. Statistical analyses tended to confirm significant Middle Eastern genetic contribution. This study gives a new perspective to the large human genetic diversity in Madagascar