Fast contactless vibrating structure characterization using real time field programmable gate array-based digital signal processing: Demonstrations with a passive wireless acoustic delay line probe and vision

International audienceVibrating mechanical structure characterization is demonstrated using contactless techniques best suited for mobile and rotating equipments. Fast measurement rates are achieved using Field Programmable Gate Array (FPGA) devices as real-time digital signal processors. Two kinds of algorithms are implemented on FPGA and experimentally validated in the case of the vibrating tuning fork. A first application concerns in-plane displacement detection by vision with sampling rates above 10 kHz, thus reaching frequency ranges above the audio range. A second demonstration concerns pulsed-RADAR cooperative target phase detection and is applied to radiofrequency acoustic transducers used as passive wireless strain gauges. In this case, the 250 ksamples/s refresh rate achieved is only limited by the acoustic sensor design but not by the detection bandwidth. These realizations illustrate the efficiency, interest, and potentialities of FPGA-based real-time digital signal processing for the contactless interrogation of passive embedded probes with high refresh rates

Investigation of Lasing in Highly Strained Germanium at the Crossover to Direct Band Gap

Efficient and cost-effective Si-compatible lasers are a long standing wish of the optoelectronic industry. In principle, there are two options. For many applications, lasers based on III-V compounds provide compelling solutions, even if the integration is complex and therefore costly. However, where low costs and also high integration density are crucial, group-IV-based lasers - made of Ge and GeSn, for example - could be an alternative, provided their performance can be improved. Such progresses will come with better materials but also with the development of a profounder understanding of their optical properties. In this work, we demonstrate, using Ge microbridges with strain up to 6.6%, a powerful method for determining the population inversion gain and the material and optical losses of group IV lasers. This is made by deriving the values for the injection carrier densities and the cavity losses from the measurement of the change of the refractive index and the mode linewidth, respectively. We observe a laser threshold consistent with optical gain and material loss values obtained from a tight binding calculation. Lasing in Ge - at steady-state - is found to be limited to low temperatures in a narrow regime of tensile strain at the crossover to the direct band gap bandstructure. We explain this observation by parasitic intervalence band absorption that increases rapidly with higher injection densities and temperature. N-doping seems to reduce the material loss at low excitation but does not extend the lasing regime. We also discuss the impact of the optically inactive carriers in the L-valley on the linewidth of group IV lasers.Comment: 29 pages, 70 references, 15 figure

Type I IFN controls chikungunya virus via its action on nonhematopoietic cells

Chikungunya virus (CHIKV) is the causative agent of an outbreak that began in La Réunion in 2005 and remains a major public health concern in India, Southeast Asia, and southern Europe. CHIKV is transmitted to humans by mosquitoes and the associated disease is characterized by fever, myalgia, arthralgia, and rash. As viral load in infected patients declines before the appearance of neutralizing antibodies, we studied the role of type I interferon (IFN) in CHIKV pathogenesis. Based on human studies and mouse experimentation, we show that CHIKV does not directly stimulate type I IFN production in immune cells. Instead, infected nonhematopoietic cells sense viral RNA in a Cardif-dependent manner and participate in the control of infection through their production of type I IFNs. Although the Cardif signaling pathway contributes to the immune response, we also find evidence for a MyD88-dependent sensor that is critical for preventing viral dissemination. Moreover, we demonstrate that IFN-α/β receptor (IFNAR) expression is required in the periphery but not on immune cells, as IFNAR−/−→WT bone marrow chimeras are capable of clearing the infection, whereas WT→IFNAR−/− chimeras succumb. This study defines an essential role for type I IFN, produced via cooperation between multiple host sensors and acting directly on nonhematopoietic cells, in the control of CHIKV

Alternative Oxidase Expression in the Mouse Enables Bypassing Cytochrome c Oxidase Blockade and Limits Mitochondrial ROS Overproduction

Peer reviewe

Electronics dedicated to oscillators and psysical mesurement using elastic wave sensors

Le travail en bande de base permet de s’affranchir du bruit de multiplication de fréquenced’un signal. Cependant, la conception d’un oscillateur fonctionnant à haute fréquence nécessited’avoir un composant sélectif en fréquence, fonctionnant à haute fréquence et avec un facteurde qualité élevée. L’approche proposée dans cette thèse consiste à évaluer un composant à ondeélastique de volume à harmoniques élevées, le HBAR, pour la réalisation d’un oscillateur compactet stable, travaillant en bande de base à 2,45 GHz, à des fins d’utilisation de source defréquence pour un système RADAR. Les oscillateurs réalisés présentent un bruit de phase de-100 dBc/Hz pour un écart à la porteuse de 1 kHz, avec une perspective d’amélioration d’une dizainede dBc/Hz de cette valeur d’après la simulation. L’étude porte également sur l’analyse del’influence du bruit de phase de l’oscillateur local sur la résolution d’une mesure RADAR dontl’effet est démontré expérimentalement en utilisant une ligne à retard à onde élastique de surface(SAW) comme cible RADAR coopérative. Le travail effectué sur cette cible coopérative apermis d’aboutir à un prototype d’électronique embarqué pour l’interrogation de lignes à retardà ondes élastiques utilisées en tant que capteurs passifs interrogeables à distance. L’architecturede l’interrogateur combine une méthode RADAR impulsionnelle à un système d’échantillonnageen temps équivalent permettant de réduire l’importance de la puissance de calcul dansle traitement de la réponse. Les inconvénients de l’échantillonnage en temps équivalent sontminimisés par une interrogation judicieuse pour acquérir seulement les points nécessaires à lamesure. Les mesures effectuées sur un capteur de température commercial présentent une résolutionde 0,2°C avec une bande passante de 35 kHz. Pour les applications nécessitant une bandepassante plus élevée (allant jusqu’à 200 kHz), un second prototype n’ayant pas de restrictionsur les ressources de calcul mises en oeuvre est également présenté dans cette thèse, combinantla même méthode impulsionnelle avec un échantillonnage en temps réel.Eliminating the step of frequency multiplication, by working in baseband, reduces the phasenoise of an oscillator. However, the design of a high frequency oscillator requires a frequencyselective component, which operates at high frequency and with a high quality factor. The approachproposed in this thesis is to evaluate a High-overtone Bulk Acoustic-wave Resonator,the HBAR, for the realization of a compact and stable oscillator at 2.45 GHz for a RADAR system.The designed oscillator exhibits a phase noise of −100 dBc/Hz at 1 kHz from the carrier,with an expected improvement of a dozen dBc/Hz according to the simulation. The study alsofocuses on the analysis of the local oscillator phase noise impact on the resolution of a RADARmeasurement and an experimental demonstration is done using a delay line surface acousticwave (SAW) as cooperative RADAR target. The work on this cooperative target has lead to aprototype of an embedded electronics for interrogating surface acoustic wave delay lines usedas passive sensors remotely interrogated through a wireless link. The architecture combines thepulsed RADAR signal generation method with an equivalent time sampling system in orderto reduce the computing power needed to process the response. The disadvantages of equivalenttime sampling are minimized by a smart interrogation strategy to acquire only mandatorysamples. Measurements on a commercial temperature sensor have a resolution of 0.2°C witha 35 kHz bandwidth. For applications in need of higher bandwidth (up to 200 kHz), a secondprototype with no restriction on computing resources is also presented in this thesis, combiningthe same impulse RADAR method with real-time sampling

Electroniques dédiées à l'asservissement d'oscillateurs et à la mesure physique à l'aide de capteurs à ondes élastiques

Eliminating the step of frequency multiplication, by working in baseband, reduces the phasenoise of an oscillator. However, the design of a high frequency oscillator requires a frequencyselective component, which operates at high frequency and with a high quality factor. The approachproposed in this thesis is to evaluate a High-overtone Bulk Acoustic-wave Resonator,the HBAR, for the realization of a compact and stable oscillator at 2.45 GHz for a RADAR system.The designed oscillator exhibits a phase noise of −100 dBc/Hz at 1 kHz from the carrier,with an expected improvement of a dozen dBc/Hz according to the simulation. The study alsofocuses on the analysis of the local oscillator phase noise impact on the resolution of a RADARmeasurement and an experimental demonstration is done using a delay line surface acousticwave (SAW) as cooperative RADAR target. The work on this cooperative target has lead to aprototype of an embedded electronics for interrogating surface acoustic wave delay lines usedas passive sensors remotely interrogated through a wireless link. The architecture combines thepulsed RADAR signal generation method with an equivalent time sampling system in orderto reduce the computing power needed to process the response. The disadvantages of equivalenttime sampling are minimized by a smart interrogation strategy to acquire only mandatorysamples. Measurements on a commercial temperature sensor have a resolution of 0.2°C witha 35 kHz bandwidth. For applications in need of higher bandwidth (up to 200 kHz), a secondprototype with no restriction on computing resources is also presented in this thesis, combiningthe same impulse RADAR method with real-time sampling.Le travail en bande de base permet de s’affranchir du bruit de multiplication de fréquenced’un signal. Cependant, la conception d’un oscillateur fonctionnant à haute fréquence nécessited’avoir un composant sélectif en fréquence, fonctionnant à haute fréquence et avec un facteurde qualité élevée. L’approche proposée dans cette thèse consiste à évaluer un composant à ondeélastique de volume à harmoniques élevées, le HBAR, pour la réalisation d’un oscillateur compactet stable, travaillant en bande de base à 2,45 GHz, à des fins d’utilisation de source defréquence pour un système RADAR. Les oscillateurs réalisés présentent un bruit de phase de-100 dBc/Hz pour un écart à la porteuse de 1 kHz, avec une perspective d’amélioration d’une dizainede dBc/Hz de cette valeur d’après la simulation. L’étude porte également sur l’analyse del’influence du bruit de phase de l’oscillateur local sur la résolution d’une mesure RADAR dontl’effet est démontré expérimentalement en utilisant une ligne à retard à onde élastique de surface(SAW) comme cible RADAR coopérative. Le travail effectué sur cette cible coopérative apermis d’aboutir à un prototype d’électronique embarqué pour l’interrogation de lignes à retardà ondes élastiques utilisées en tant que capteurs passifs interrogeables à distance. L’architecturede l’interrogateur combine une méthode RADAR impulsionnelle à un système d’échantillonnageen temps équivalent permettant de réduire l’importance de la puissance de calcul dansle traitement de la réponse. Les inconvénients de l’échantillonnage en temps équivalent sontminimisés par une interrogation judicieuse pour acquérir seulement les points nécessaires à lamesure. Les mesures effectuées sur un capteur de température commercial présentent une résolutionde 0,2°C avec une bande passante de 35 kHz. Pour les applications nécessitant une bandepassante plus élevée (allant jusqu’à 200 kHz), un second prototype n’ayant pas de restrictionsur les ressources de calcul mises en oeuvre est également présenté dans cette thèse, combinantla même méthode impulsionnelle avec un échantillonnage en temps réel

Mobile homeless : vehicle-living, off-grid connection, and the building of an informal home

Research on informal housing has predominantly focused on formations occurring in the Global South, with less empirical focus on the Global North. Utilizing data from qualitative interviews with people practicing vehicle-living in the Metro Vancouver region, this study diverges from the Global South approach, by examining how individuals living out of their vehicles attempt to connect to the urban technological grid, and how these intermittent connections help people build and recreate a sense of home within makeshift, “illegitimate” living spaces. The results of this study contribute to the sociological literature on vehicle-living and housing inequalities, and helps expand the field of informal housing studies through the exploration of a form of mobile makeshift housing occurring within the specific material and socio-economic conditions of the Global North.Arts, Faculty ofSociology, Department ofGraduat

Facteurs prédictifs d apparition et d évolution des endofuites de type 2 dans les endoprothèses aortiques abdominales

Le traitement endovasculaire des anévrismes de l aorte abdominale consiste à exclure par voie endovasculaire un anévrisme de la circulation systémique, protégeant ainsi le patient du risque de décès par rupture anévrismale. Développée et étudiée depuis la fin des années 80, cette technique comporte comme complications principales les endofuites qui entrainent une remise en charge du sac anévrismal. Parmi elles, les endofuites de type 2 (EF2) sont les plus fréquentes et ont une physiopathologie inexpliquée pour le moment. Le but de notre travail a été de rechercher des facteurs prédictifs de l apparition et de l évolution des EF2. Nous avons pour cela étudié des données anatomiques : les artères collatérales aortiques, le thrombus anévrismal et un élément original : la surface de cavité juxta prothétique. Nos travaux ont permis de confirmer le rôle protecteur d un important thrombus anévrismal, en particulier lorsque celui-ci était situé en position postérieure. Nous avons pu démontrer le rôle péjoratif d un nombre important de collatérales sur la croissance du sac anévrysmal. Chez ces mêmes patients, l étude de la cavité juxta prothétique a montré une corrélation sur l évolution du collet proximal et ouvre de nouvelles perspectives dans l approche physiopathologique des endofuites.DIJON-BU Médecine Pharmacie (212312103) / SudocSudocFranceF

Geochemical behaviour, fate and impacts of Cu, Cd and Zn from mine effluent discharges in Howe Sound

The now abandoned mine at Britannia Beach is a source of acidity and heavy metals to Howe Sound. Using evidence from monthly field sample collections over an entire year, the dispersion patterns of Cu, Cd and Zn in the estuary were elucidated. Acid mine drainage discharged to Howe Sound via Britannia Creek was found to mix predominantly with the brackish surface waters, since a pronounced pycnocline inhibits vertical mixing. Deep discharges via a submarine outfall may become trapped at or below ten metres depth during summer, but have been observed to rise to the surface in winter as a result of weaker stratification. Upon mixing with estuarine water, there was generally a transfer of Cu from the dissolved to the particulate phase. Similar removal was observed with Zn, albeit to a much lesser degree. Cd behaved essentially as a conservative element, which permitted its use as a tracer for the mixing of acid mine drainage with seawater. This greatly facilitated interpretation of the field data, since salinity proved to be an unreliable indicator of mixing in this three end-member system of Squamish River, Britannia Creek and seawater. Laboratory mixing experiments demonstrated that the removal of Zn occurred via adsorption onto iron oxyhydroxides, with other processes such as adsorption by flocculated organic matter or by clays playing a less important role. Cu removal was additionally governed to a large extent by direct precipitation of solid phases, most likely Cu(OH)2. Mixing experiments and speciation calculations suggest that Cu, and possibly Zn, may be present to a large degree in colloidal suspension. Metal concentrations in estuarine surface waters ranged between 0.8 - 230, 0.02 - 2.9 and 1.7 - 450 μg/L for Cu, Cd and Zn, respectively at a site some 350 m off the mouth of Britannia Creek. They were found to be controlled by the supply from acid mine drainage, by dilution with Squamish River runoff, and by the extent of removal in the creek mixing zone. All these parameters are strongly seasonal due to their dependence on hydrological conditions. They combined to produce maximum surface metal concentrations in spring and winter, as demonstrated using both field data and model calculations. In a bioassay experiment, Cu concentrations over 6.4 μg/L affected growth of endemic phytoplankton adversely. This level was found to be exceeded in 13 out of 26 field observations in Britannia Bay. In spring, concentrations that could produce detrimental effects on phytoplankton may also extend several kilometres down-estuary.Science, Faculty ofEarth, Ocean and Atmospheric Sciences, Department ofGraduat