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31 results on '"Serviere, J."'

7. Analysis of Clamped Inductive Turnoff Failure in Railway Traction IGBT Power Modules Under Overload Conditions

Author

Perpiñà, X., Serviere, J. F., Urresti, J., Cortés, Ignasi, Jordà, Xavier, Hidalgo, Salvador, Rebollo, J., Mermet-Guyennet, M., Perpiñà, X., Serviere, J. F., Urresti, J., Cortés, Ignasi, Jordà, Xavier, Hidalgo, Salvador, Rebollo, J., and Mermet-Guyennet, M.

Abstract

This paper studies the overload turnoff failure in the insulated-gate bipolar transistor (IGBT) devices of power multichip modules for railway traction. After a detailed experimental analysis carried out through a dedicated test circuit, electrothermal simulations at device level are also presented. The simulation strategy has consisted in inducing a current and temperature mismatch in two IGBT cells. Results show that mismatches in the electrothermal properties of the IGBT device during transient operation can lead to uneven power dissipation, significantly enhancing the risk of failure and reducing the lifetime of the power module. Concretely, simulations qualitatively demonstrate that localized hot-spot formation due to a dynamic breakdown could lead to a second breakdown mechanism.

Published
2011

8. IGBT module failure analysis in railway applications

Author

Perpiñà, X., Serviere, J. F., Jordà, Xavier, Fauquet, A., Hidalgo, Salvador, Urresti, J., Rebollo, J., Mermet-Guyennet, M., Perpiñà, X., Serviere, J. F., Jordà, Xavier, Fauquet, A., Hidalgo, Salvador, Urresti, J., Rebollo, J., and Mermet-Guyennet, M.

Abstract

This work reports two different characteristic patterns detected in IGBT chips failed in real operation (railway application) by failure analysis procedures. The analysed chips have been recovered from the rheostatic chopper leg and from the three legs which supplies the traction motor. It is observed that depending on the location and characteristics of the detected default (burn-out spot), this failure can be attributed to a latch-up process or a secondary breakdown mechanism. These results are corroborated with tests at limit, obtaining the same result. Consequently, each failure can be linked to overcurrent (latch-up) or overtemperature (secondary breakdown) events, which makes possible to distinguish between problems coming from driving strategies or thermal issues (uneven temperature distribution inside the module or packaging wear-out).

Published
2008

10. Temperature measurement on series resistance and devices in power packs based on on-state voltage drop monitoring at high current

Author

Perpiñà, X., Serviere, J. F., Mermet-Guyennet, M., Millán, José, Perpiñà, X., Serviere, J. F., Mermet-Guyennet, M., and Millán, José

Abstract

Based on the on-state voltage drop monitoring at high current, an alternative method for thermo-sensitive parameters calibration is reported. The main goal is that it allows the simultaneous calibration of the series resistance and power devices voltage drop on temperature. Thereby, the average temperature over all power devices and the temperature difference in average inside the pack can be measured in real applications.

Published
2006

13. Vomeronasal activation by urine in the primate Microcebus murinus: A 2 DG study.

Author

Schilling, A., Serviere, J., Gendrot, G., and Perret, M.

Abstract

The vomeronasal system (VNS) seems to be functional in some primates and involved in the detection of urinary signals. Anterograde tracing (WGA-HRP) and evoked metabolic activity (2-DG method) were used in order to clarify the conditions under which the VNS is activated in the prosimian mouse lemur. After WGA-HRP deposition at one of the oral entries of the nasopalatine duct, reaction product was observed within the accessory bulb (AOB). 2-DG experiments show that urine in the volatile phase stimulates the main but not the accessory bulb (AOB). Liquid urine produced bilateral or unilateral activation of AOB depending on whether the stimulation was exclusively unilateral or not; under the same conditions distilled water could not produce 2-DG labelling. It is concluded that VNS is activated by urine in the liquid but not the volatile phase. The biological implications of these results are discussed. [ABSTRACT FROM AUTHOR]

Published
1990
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17. Minimising pain in farm animals: the 3S approach - 'Suppress, Substitute, Soothe'

Author

Guatteo, R., Levionnois, Olivier, Fournier, D., Guemene, D., Latouche, K., Leterrier, C., Mormede, P., Prunier, A., Serviere, J., Terlouw, C., and Le Neindre, P.

Subjects
2. Zero hunger, 630 Agriculture
Abstract

Recently, the French National Institute for Agricultural Research appointed an expert committee to review the issue of pain in food-producing farm animals. To minimise pain, the authors developed a '3S' approach accounting for 'Suppress, Substitute and Soothe' by analogy with the '3Rs' approach of 'Reduction, Refinement and Replacement' applied in the context of animal experimentation. Thus, when addressing the matter of pain, the following steps and solutions could be assessed, in the light of their feasibility (technical constraints, logistics and regulations), acceptability (societal and financial aspects) and availability. The first solution is to suppress any source of pain that brings no obvious advantage to the animals or the producers, as well as sources of pain for which potential benefits are largely exceeded by the negative effects. For instance, tail docking of cattle has recently been eliminated. Genetic selection on the basis of resistance criteria (as e.g. for lameness in cattle and poultry) or reduction of undesirable traits (e.g. boar taint in pigs) may also reduce painful conditions or procedures. The second solution is to substitute a technique causing pain by another less-painful method. For example, if dehorning cattle is unavoidable, it is preferable to perform it at a very young age, cauterising the horn bud. Animal management and constraint systems should be designed to reduce the risk for injury and bruising. Lastly, in situations where pain is known to be present, because of animal management procedures such as dehorning or castration, or because of pathology, for example lameness, systemic or local pharmacological treatments should be used to soothe pain. These treatments should take into account the duration of pain, which, in the case of some management procedures or diseases, may persist for longer periods. The administration of pain medication may require the intervention of veterinarians, but exemptions exist where breeders are allowed to use local anaesthesia (e.g. castration and dehorning in Switzerland). Extension of such exemptions, national or European legislation on pain management, or the introduction of animal welfare codes by retailers into their meat products may help further developments. In addition, veterinarians and farmers should be given the necessary tools and information to take into account animal pain in their management decisions.

31. [Understanding the action of the circadian clock: from phenomenologic ideas to molecular activity].

Author

Serviere J

Subjects
Afferent Pathways physiology, Aging physiology, Animals, Humans, Neurons physiology, Circadian Rhythm physiology, Hypothalamus physiology, Neuropeptides physiology, Suprachiasmatic Nucleus physiology
Abstract

The focus of the present review is to present recent studies of the mammalian circadian clock located in the suprachiasmatic nuclei (SCN) of the hypothalamus. The main questions in circadian neuroscience are: how many oscillators are implicated, how are their daily oscillations generated and synchronized to the external environment and how does the central clock send timed signals to the whole organism. The review is introduced by a presentation of circadian system properties and by a description of the responses to manipulations of the main entraining factor, i.e. the light-dark cycle. The anatomy of the SCN and its major afferents from the retina (glutamate, Substance P), raphe (serotonin) and intergeniculate leaflet (neuropeptide Y) of the thalamus are presented with a special emphasis on the interaction of these inputs with the circadian timekeeping mechanism. The arguments related to the issue of whether the retina contain an endogenous oscillator are exposed. What is known of the endogenous mechanism(s) of this small structure containing 10,000 or so "self-oscillating neurons" is reviewed through: i) the anatomical distribution and functional significance of clock-peptides (VIP, PHI, GRP, VP or SS), ii) the putative involvement of the SCN astrocytic population in coordinating neuronal activities, iii) the various aspects of cellular activity (electrical activity, energy metabolism, protein or peptide synthesis) and iv) the participation of immediate early genes in light-driven phase shifts. The present understanding of molecular timekeeping mechanism is exposed in light of the growing list of candidate clock-genes described within the SCN as well as in peripheral tissues of mammals and also in the clock-systems of phylogenetically lower species. Efferents from the SCN are also discussed with an interest toward understanding how the central circadian information is transmitted to the rest of the brain in order to impulse or/and coordinate the numerous rhythmic activities of the organism. Finally, cellular disturbances in peptide expression or content, reduction in the amplitude of a given functional index or even astrocytic proliferation are viewed along the line of pathologies observed with aging.

Published
1998

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