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Strong spin–phonon coupling in Gd-filled nanotubes
Get PDFTo develop one-dimensional spintronic devices, we synthesize Gd-filled double-walled carbon nanotubes where the long spin-coherence time of a paramagnetic gadolinium (Gd3+) ion and the discrete phonon modes of a carbon nanotube can be combined. Here, we report Raman observation of spin–phonon coupling in the Gd-filled double-walled nanotubes by analyzing the low-temperature dependence of the dominant phonon modes (G-band). A G-band (w+G ext and w +G int) phonon frequency hardening is observed below a critical temperature of TC ∼ 110 K coinciding with the onset temperature of superparamagnetic behavior confirmed through magnetization studies. This anomalous behavior is ascribed to phonon renormalization induced by spin–phonon coupling interaction. The estimated spin–phonon coupling constant values are 12.2 and 5.0 cm−1 for G +ext and G +int phonon modes, respectively, analyzed by comparing the phonon frequency variation (Δw) to magnetization as a function of temperature. Realizing a spin–phonon coupling (three times higher than for other multiferroic compounds) interface and modulating it in a one-dimensional system have potential benefit when designing effective molecular qubits
Laser welding of AISI 316L stainless steel produced by additive manufacturing or by conventional processes
Get PDFAmong all the additive manufacturing techniques, Laser Powder Bed Fusion (LBPF), also called Selective Laser Melting (SLM), is the most common technique due to its high capability of building complex parts with generally improved mechanical properties. One of the main drawbacks of this technique is the sample size limitation, which depends on elaborating chamber dimensions. In this study, we investigate the viability of obtaining large parts with the laser welding of additive manufactured plates. A comparison of the microstructure and the tensile mechanical properties of SLM-welded plates and cold-rolled welded plates was performed. This paper shows the possibility of obtaining defect-free parts. Even if welding has a low impact on the microstructure of the SLM samples, fractures are located on the fusion zone, and a decrease in ductility of around 30% compared to the base metal is observed
Dynamiques territoriales et gestion de la Fièvre Porcine Africaine : rétrospective bibliographique et étude de terrain dans le Sud-Ouest français
Get PDFLa Fièvre Porcine africaine est une maladie virale mortelle affectant les suidés et qui tend à se propager rapidement en Europe et dans le monde depuis le début du siècle. Les pays encore indemnes se doivent de mettre en place des mesures de prévention strictes car l'introduction du virus a de graves conséquences économiques pour les pays. Une surveillance accrue de la faune sauvage, des mesures de biosécurité en élevages ainsi que des campagnes de sensibilisation ont été initiées en France, pays voisin de la Belgique, récemment contaminée et de la Sardaigne où la maladie est endémique. De nombreuses mesures très coûteuses sont imposées aux éleveurs. Les vétérinaires ont un rôle de conseil dans leur mise en place. Les chasseurs sont impliqués dans la surveillance de la faune sauvage. Les institutions mettent à disposition un grand nombre de supports de communication afin de sensibiliser sur la maladie et sur les gestes à adopter
Worst-case pointing performance analysis for large flexible spacecraft
Get PDFThis paper presents a tool, PELIB, developed in MATLAB /SIMULINK environment to perform pointing performance analysis based on European pointing standards. PELIB is designed as an extension of the Satellite Dynamics Toolbox (SDT), which derives the Linear Fractional Transformation (LFT) models of flexible space structures. The addition of PELIB will allow the users of SDT to perform pointing performance analysis of real mission scenarios in the same environment used for control synthesis. PELIB offers as well the possibility to take into account uncertainties in the system. This feature represents an enhancement to the current verification tools available in the European space industry community by providing the worst-case pointing budget. The capabilities of PELIB were demonstrated in a case study involving a spacecraft model with two flexible solar arrays. Several error sources as well as uncertain parameters were included in this model. The nominal performance has been investigated using PELIB and compared with the current European reference tool. The worst-case performance is also investigated with the new feature of PELIB to obtain the worst-case performance budget
Autonomous navigation system for free floating experiments in parabolic flights
Get PDFThis paper presents the development of an Extended Kalman Filter for the navigation system of a spacecraft in a parabolic flight. The algorithm blends the measurements coming from two Inertia Measurement Units, one mounted on the spacecraft and one on the baseplate of the aircraft; and a camera system connected to the baseplate as well. During the zero-g phases the attitude and position of the spacecraft in the experimental area are recovered thanks to a series of Alvar markers attached on the spacecraft casing and detected by the camera system. Results from parabolic test campaign of October 2019 are finally presented
Lead-acid battery state-of-health evaluation with short discharge method
Get PDFElectricity access to rural areas in third world countries is still a big problem. Second-life components can present a good solution for these areas as solar PV (Photo-Voltaic) panels can still be used after twenty five years of use. PSUs (power supply units) from computers can be used as solar charge controllers after just a little change while batteries can also be used in their second-life when they are eliminated from their first use. This second life use of electrical components is done with the frugal innovation principles. But using batteries in second-life requires SoH accurate measurement which is still difficult with already existing methods especially when history of battery is unknown. In this paper, a new method is introduced based on short discharge of the battery. This method is cheap, fast, reliable and accurate enough for second-life batteries. A second-life battery means that when a battery is done for its life but still it can be used for small load than before. The method can be applied in two different ways and maximum error for both variations is around 10% which is very much acceptable for second-life batteries. The well-known two-pulse method is also performed to compare results for same conditions and error can be as high as 55% in some cases. The method is equally good for flooded (car) and AGM (solar) lead-acid batteries. The method introduced in the paper highly relies on SoC accurate measurement. Here, two-pulse method is used as SoC measurement method with short discharge method
On the potting failure of inserts for sandwich panels: defects review and experimental analysis
Get PDFIn this paper the potting failures of inserts in sandwich structure is analyzed. The case
of inserts potted with syntactic foam is investigated. First, a discussion about the influence of
defects is made. Then, an experimental campaign is performed to determine the traction and
compression behavior of the syntactic foam. Later, a specific technological pull-out test was
performed, while a DIC system was used to record the tests. This allowed to observe and
understand the different potting failure modes of inserts for sandwich panels. The obtained
results suggest that the potting failure of inserts is predominant when fabrication or
installation defects are present
Optimisation de la méthode de coproscopie sur échantillons de litière pour le diagnostic collectif des infections par les coccidies chez les agneaux
Get PDFLa coccidiose, causée par des protozoaires intracellulaires obligatoires du genre Eimeria, est une maladie à fortes répercussions économique et sanitaire pour les élevages ovins. Actuellement, la technique de préparation utilisée pour le diagnostic collectif sur litière est le tri à la main, chronophage et peu répétable. Cette étude a donc pour objectif d’optimiser la méthode d’analyse de litière en comparant le tri à la main avec un nouveau protocole : la sédimentation. Pour ce faire, plusieurs échantillons de litière de quatre loges ont été analysés conjointement avec les deux méthodes de préparation. En parallèle, des fèces récoltées directement au rectum d’agneaux d’engraissement appartenant à ces mêmes loges ont été analysées pour déterminer si les techniques de préparation des échantillons de litière reflétaient la réelle excrétion fécale. Plusieurs facteurs ont été comparés entre les deux méthodes parmi lesquels leur mise en œuvre, leur corrélation aux fèces individuelles et la composition des échantillons. Ainsi, d’après cette étude, le tri à la main est la méthode répondant à un plus grand nombre de critères. La technique de sédimentation nécessite donc d’être améliorée afin d’optimiser le diagnostic collectif de coccidiose
Protocoles de prise en charge des poussins de quelques espèces d'oiseaux sauvages fréquemment reçues en centre de soins, exemple de l’École Nationale Vétérinaire de Toulouse
Get PDFLes oiseaux juvéniles représentent près de la moitié des animaux admis au Centre de Soins de l’École Nationale Vétérinaire de Toulouse. Leur prise en charge nécessite une zootechnie particulière et des protocoles spécifiques, différents de ceux appliqués pour les adultes. Le but de cette thèse est de répertorier, pour certaines des espèces les plus communément admises, les connaissances sur la biologie du développement d’un oiseau juvénile jusqu’à son indépendance, afin d’adapter au mieux sa prise en charge en centre de soins. Les principales affections rencontrées sur des oiseaux juvéniles y sont également décrites. Systématiser la prise en charge d’oiseaux juvénile permet un gain de temps et d’efficacité considérable. Ainsi, cette thèse propose des fiches protocoles par espèce récapitulant la croissance physiologique de l’animal et associant un plan d’alimentation et des suggestions de conditions d’hébergements
Towards a combination of MARTE and ECOA
Get PDFThrough the definition of a metamodel, the ECOA (European Component Oriented Architecture) open standard offers a development framework for complex avionic systems software. Its purpose is to create and maintain architectures to achieve interoperability, sustainability and portability at both functional and software interface level.
However, being a metamodel, ECOA only offers an abstract syntax and theoretical concepts to develop software and their interfaces. It therefore suffers from a lack of modeling language, tools and methods enabling real-time analysis during the development process of software. Combining the rigour of the ECOA metamodel with the potential of model-based analysis would not only allow a reduction in development time of complex software-based systems but also help improving system optimality with respect to hard real-time requirements.
Translation of ECOA concepts into a formally defined and tooled modeling language is thus an avenue to explore. This paper advocates for using the UML real-time profile MARTE (Modeling and Analysis of Real-Time and Embedded systems) as it offers both a concrete syntax to complete the ECOA metamodel as well as a modeling method thanks to its own metamodel.
Results of a preliminary study are presented both in terms of ECOA to MARTE translation and perspectives for real-time analysis of models