Filtrage non linéaire pour la conception d'un brouilleur intelligent

Cet article traite de la conception d'un brouilleur "intelligent" dans le cas où les signaux émis sont non linéaires. Le terme "intelligent" est employé car le brouilleur doit être capable de suivre l'évolution des caractéristiques du signal à brouiller. En effet, ce brouilleur doit simultanément émettre un signal de brouillage (de fort niveau) et estimer les caractéristiques du signal utile (de faible niveau). La solution originale retenue est basée sur l'utilisation d'une séquence de brouillage à faible pouvoir d'excitation. Cette solution a été validée sur signaux sonar sous-marins par une procédure de traitement non linéaire des données montrant la faisabilité de la conception d'un brouilleur "intelligent"

Filtrage adaptatif non-linéaire utilisant une entrée cyclostationnaire

Cet article compare différents signaux de référence pour un filtrage adaptatif de Volterra à temps discret pour une application spécifique : le brouilleur. L'originalité de cette étude est d'utiliser une référence cyclostationnaire pour exciter le moins possible les modes du système inconnu étudié. Cette nouvelle approche permet d'obtenir un modèle de Volterra minimal car tous les termes non excités sont alors rejetés

Performance of creatinine-based equations to estimate glomerular filtration rate in White and Black populations in Europe, Brazil and Africa.

peer reviewed("[en] BACKGROUND: A new Chronic Kidney Disease Epidemiology Collaboration equation without the race variable has been recently proposed (CKD-EPIAS). This equation has neither been validated outside USA nor compared with the new European Kidney Function Consortium (EKFC) and Lund-Malmö Revised (LMREV) equations, developed in European cohorts. METHODS: Standardized creatinine and measured glomerular filtration rate (GFR) from the European EKFC cohorts (n = 13 856 including 6031 individuals in the external validation cohort), from France (n = 4429, including 964 Black Europeans), from Brazil (n = 100) and from Africa (n = 508) were used to test the performances of the equations. A matched analysis between White Europeans and Black Africans or Black Europeans was performed. RESULTS: In White Europeans (n = 9496), both the EKFC and LMREV equations outperformed CKD-EPIAS (bias of -0.6 and -3.2, respectively versus 5.0 mL/min/1.73 m², and accuracy within 30% of 86.9 and 87.4, respectively, versus 80.9%). In Black Europeans and Black Africans, the best performance was observed with the EKFC equation using a specific Q-value (= concentration of serum creatinine in healthy males and females). These results were confirmed in matched analyses, which showed that serum creatinine concentrations were different in White Europeans, Black Europeans and Black Africans for the same measured GFR, age, sex and body mass index. Creatinine differences were more relevant in males. CONCLUSION: In a European and African cohort, the performances of CKD-EPIAS remain suboptimal. The EKFC equation, using usual or dedicated population-specific Q-values, presents the best performance in the whole age range in the European and African populations included in this study.","[en] ",""

Aide au diagnostic de défauts des transformateurs de puissance

Les transformateurs de puissance sont des éléments clés des systèmes électriques. Leurs défaillances sont très coûteuses, principalement à cause de la non-disponibilité du service électrique qu'elles entraînent. L'évaluation rapide et précise de défauts internes des transformateurs est en conséquence un facteur clé d'une exploitation efficace et sûre. Un tel diagnostic est généralement établi par un expert humain qui fait corréler différents types d'informations telles que des résultats d'essais électriques ou chimiques, le déclenchement de protections ou l'historique de l'appareil Cette thèse présente une méthode d'aide au diagnostic de défauts originale qui reprend, en les formalisant, la démarche et la capitalisation d'expérience de l'expert. Les informations disponibles sur le transformateur à étudier sont mises en correspondance avec le système proposé de manière systématique. Des hypothèses de défaut sont alors formulées et un degré de confiance calculé pour chacune d'elle. Pour améliorer la confiance en certaines de ces hypothèses la méthode recherche, et propose, de renseigner des informations utiles pouvant améliorer le diagnostic. Il progresse ainsi jusqu'à ce que la confiance d'au moins une hypothèse soit suffisante pour l'utilisateur. Le système peut de plus évoluer efficacement dans le temps en prenant facilement en compte de nouveaux types d'essais ou de nouvelles informations pouvant être discriminants dans un diagnostic, et ainsi améliorer les diagnostics futurs automatiquement.Power transformers are keys components to the electrical systems. Its failures are very expensive mostly by causing long electrical service unavailability. Quick and accurate assess of transformer's internal faults is consequently a key issue for an efficient and safe service life. Such diagnosis is mainly led by a human expert, due to his ability to link together many different kind of information as electrical or chemical tests, tripped protections or history of the apparatus This thesis presents an original method of diagnosis aid that behaves somehow like an expert, and capitalizes his experience, by formalizing it. The available information on a particular transformer are used to search any similarities within the developed system, on a systematic base. Then faults hypothesis are proposed and according confidences are calculated. To improve those hypothesis' confidences the method will propose to inform new useful information that could improve the diagnosis. Then it continues up until at least one hypothesis confidence is high enough for the user. This system could easily evolve over time by taking into account new kind of tests or new information that could be significant in any diagnosis, and then improve future diagnosis automatically.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Méthodes et outils d'aide au diagnosticet à la maintenance des tableaux électriques généraux par le suivi des grandeurs physiques caractéristiques et de leur fonctionnement

Le tableau électrique est un élément clé de toute installation électrique. Il incorpore des dispositifs destinés à distribuer l'électricité et à protéger les circuits et les personnes. Cette thèse porte sur un système de surveillance et de diagnostic des tableaux BT, basé sur les mesures de températures, et de courants. Ce système innovant répond au besoin de prévenir les pannes, qui, bien que rares, peuvent entrainer des pertes financières énormes. Les mesures thermiques sont réalisées à l'aide de capteurs sans fil. Les données mesurées sont transmises via internet et collectées dans un serveur, pour être traitées. Ce traitement comprend une phase de détection locale de défaut et une autre de diagnostic global conduisant à des recommandations de maintenance. Notre travail est axé sur les modules de détection et le diagnostic. Des résultats issus d'expertises et d'expérimentations sont présentés pour valider la faisabilité des méthodes mises en œuvre.The switchboard is a key element of any electrical installation. It incorporates devices designed to distribute electrical power and protect circuits and people. This PhD work deals with an entire system of monitoring and diagnosis of Low Voltage (LV) switchboards based on the measurements of temperatures, and currents. This innovating system meets the needs to prevent the breakdowns of LV switchboards, which, although rare, can involve huge financial and human loss. The thermal measurements are do ne by wireless thermal sensor. The measured data are transmitted via internet and collected in a server, to be centrally processed. This centralized data processing includes a local detection of failures and a global diagnosis which leads to sorne maintenance recommendations. This work is focused on, the detection stage, and the global diagnosis. Sorne results based on experimental data and expertise's information are presented to validate the feasibility of the methods implemented.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

A Low-Noise CMOS THz Imager Based on Source Modulation and an In-Pixel High-Q Passive Switched-Capacitor N-Path Filter

This paper presents the first low noise complementary metal oxide semiconductor (CMOS) terahertz (THz) imager based on source modulation and in-pixel high-Q filtering. The 31 × 31 focal plane array has been fully integrated in a 0 . 13 μ m standard CMOS process. The sensitivity has been improved significantly by modulating the active THz source that lights the scene and performing on-chip high-Q filtering. Each pixel encompass a broadband bow tie antenna coupled to an N-type metal-oxide-semiconductor (NMOS) detector that shifts the THz radiation, a low noise adjustable gain amplifier and a high-Q filter centered at the modulation frequency. The filter is based on a passive switched-capacitor (SC) N-path filter combined with a continuous-time broad-band Gm-C filter. A simplified analysis that helps in designing and tuning the passive SC N-path filter is provided. The characterization of the readout chain shows that a Q factor of 100 has been achieved for the filter with a good matching between the analytical calculation and the measurement results. An input-referred noise of 0 . 2 μ V RMS has been measured. Characterization of the chip with different THz wavelengths confirms the broadband feature of the antenna and shows that this THz imager reaches a total noise equivalent power of 0 . 6 nW at 270 GHz and 0 . 8 nW at 600 GHz

Intravenous Immunoglobulins in the Prevention of Rejection of a Second or Third Kidney Graft

BACKGROUND: Intravenous immunoglobulin (IVIg) reduces acute rejection episodes in kidney transplantation, but adverse events (AEs) are common. The aim of this study was to assess whether human IVIg enhances immunosuppressive effects without increasing AEs in the prevention of acute kidney graft rejection. METHODS: Patients receiving a second or third kidney graft were treated with standard immunosuppressant therapy with (n = 18) or without (n = 10) IVIg. The primary efficacy endpoint was biopsy-proven acute rejection (BPAR) rate at 3 months, and secondary endpoints included acute rejection rate at 12 months, intensity of rejection, and patient survival. RESULTS: Patients in the experimental arm received 3 infusions of IVIg. The BPAR rate decreased with IVIg versus standard immunosuppression alone over 12 months of follow-up. Experimental versus control rates of survival without BPAR were 94% versus 63% and 82% versus 63% at 3 and 12 months. The intensity of the acute rejection episodes (BANFF 97 grade) was similar between groups. One patient from each group died during the 12-month follow-up period. Treatment-emergent AEs were reported in 100% and 94.4% of the control and experimental arms. Most AEs were considered unrelated or unlikely to be related to treatment. CONCLUSIONS: This study supports the efficacy and safety of IVIg in highly sensitized transplant patients for improving transplant rates and reducing graft rejection episodes

Joints faults detection in LV switchboard and its global diaggnosis, through a Temperature Monitoring System

International audienc

Joint faults detection in LV switchboard and its global diagnosis, through a Temperature Monitoring System.

International audienceThe paper deals with an entire system of monitoring and diagnosis of LV switchboards based on the measurements of currents, ambient temperatures and local temperatures of electrical joints. This system meets the needs to prevent the breakdowns of LV switchboards, which, although rare, can involve huge financial and human loss. The thermal measurements are done by wireless thermal sensor. The measured data are transmitted via internet and collected in a server, to be centrally processed. This centralized data processing includes a local detection of failures and a global diagnosis which leads to some maintenance recommendations. This paper will focus on, the local detection by comparison with an healthy model, and the global diagnosis using Bayesian network technique. The feasibility of these methods is tested with experimental data and expert's information

Preliminary Report on the Effect of Ketamine in Patients with Central Pain

This preliminary open prospective study reports on the effect of ketamine, an N-methyl-D-aspartate (NMDA)-receptor noncompetitive antagonist, in five patients suffering from central poststroke pain (CPSP). Patients were evaluated at rest on a visual analogue scale (VAS) graded from 0 to 10. Pain measurement was repeated at 15 and 30 mins following intravenous administration of 0.15 to 0.25 mg/kg ketamine and then every 30 mins for 6 h. Pain evoked by light touch or cold stimulation was also measured in three patients at those times. Patients were monitored for arterial pressure, heart rate, sedation and side effects during the study. Ketamine provided a significant improvement in pain at rest and in evoked pain. A 51% to 84% decrease in the VAS score for pain at rest was observed within 60 to 180 mins. Satisfactory pain relief (more than 50% decrease in the VAS score) lasted for 150 to 210 mins. Two patients had a prolonged improvement over two or three days. Arterial pressure and heart rate did not change significantly. Mild or moderate sedation was noticed in all patients for 20 to 30 mins. These results suggest that blockade of NMDA receptors may provide pain relief in patients suffering from CPSP