16 research outputs found
Test estructural i predictiu per a circuits RF CMOS
En aquesta tesi sâha desenvolupat una tĂšcnica de test que permet testar un LNA i un mesclador, situats en el capçal RF dâun receptor CMOS, en una configuraciĂł de test semblant al mode normal de funcionament. La circuiteria necessĂ ria per a implementar aquesta tĂšcnica consta dâun generador IF, per a generar el senyal IF de test, i dâun mesclador auxiliar, per a obtenir el senyal RF de test. Les observables de test escollides han estat lâamplitud de la tensiĂł de sortida del mesclador i el component DC del corrent de consum. Sâha estudiat lâeficĂ cia de la tĂšcnica de test proposada utilitzant les estratĂšgies de test estructural i predictiu, mitjançant simulacions i mesures experimentals. La seva eficĂ cia Ă©s comparable a altres tĂšcniques de test existents, perĂČ lâĂ rea addicional dedicada a la circuiteria test Ă©s inferior.En esta tesis se ha desarrollado una tĂ©cnica de test que permite verificar un LNA y un mezclador, situados en el cabezal RF de un receptor CMOS, en una configuraciĂłn de test similar al modo normal de funcionamiento. Los circuitos necesarios para implementar esta tĂ©cnica son: un generador IF, que permite generar la señal IF de test, y un mezclador auxiliar, para obtener la señal RF de test. Las observables de test seleccionadas han sido la amplitud de la tensiĂłn de salida y la componente DC de la corriente de consumo. Se ha estudiado la eficacia de la tĂ©cnica propuesta usando las estrategias de test estructural y predictiva, mediante simulaciones y medidas experimentales. Su eficacia es comparable a otras tĂ©cnicas existentes, pero el ĂĄrea dedicada a la circuiteria de test es inferior.This PhD thesis develops a test technique intended for the RF front end of CMOS integrated receivers. This test technique allows testing individually the building blocks of the receiver in a sequential way. The test mode configuration of each block is similar to the normal mode operation. The auxiliary circuitry required to generate the test stimuli consists of an IF generator, which generates the IF test signal, and an auxiliary mixer that produces the RF test signal by mixing the IF test signal with the local oscillator signal. The test observables selected for the test are the voltage amplitude after the IF amplifier, and the DC component of the supply current in each block. The capability of the proposed test technique to perform structural and predictive test strategies has been validated by simulation and experimentally. Its efficiency is comparable to other existing techniques, but the silicon area overhead is lower
L'utilisation de systÚmes intelligents réseautés pour l'instrumentation des structures en génie civil
Dans cette recherche, on a conçu et validé un nouveau noeud sans fil qui sera intégré dans un systÚme automatique de contrÎle des structures de génie civil. Le prototype est conçu à partir des derniÚres technologies dans le domaine des systÚmes embarqués. Le prototype utilise la technologie développée pour les réseaux sans fil personnels WPAN (Wireless Personal Area Network) pour la transmission de données vers la centrale locale d'interrogation des données. Les capacités de calcul que le prototype possÚde nous permettent d'implémenter et d'exécuter plusieurs algorithmes de contrÎle de l'état des structures. La transformée de Fourier rapide est utilisée comme algorithme illustratif dans le noeud sans fil. L'objectif de cette recherche est de mettre en place un réseau de capteurs sans fil qui supporte le calcul collaboratif en temps réel des dominées mesurées, pour l'identification des dommages potentiels dans la structure
Aeronautical engineering: A continuing bibliography with indexes (supplement 319)
This report lists 349 reports, articles and other documents recently announced in the NASA STI Database. The coverage includes documents on the engineering and theoretical aspects of design, construction, evaluation, testing, operation, and performance of aircraft (including aircraft engines) and associated components, equipment, and systems. It also includes research and development in aerodynamics, aeronautics, and ground support equipment for aeronautical vehicles
Architecture matérielle et flot de programmation associé pour la conception de systÚmes numériques tolérants aux fautes
Whether in automotive with heat stress or in aerospace and nuclear field subjected to cosmic,neutron and gamma radiation, the environment can lead to the development of faults in electronic systems. These faults, which can be transient or permanent, will lead to erroneous results that are unacceptable in some application contexts. The use of so-called rad-hard components is sometimes compromised due to their high costs and supply problems associated with export rules.This thesis proposes a joint hardware and software approach independent of integration technology for using digital programmable devices in environments that generate faults. Our approach includes the definition of a Coarse Grained Reconfigurable Architecture (CGRA) able to execute entire application code but also all the hardware and software mechanisms to make it tolerant to transient and permanent faults. This is achieved by the combination of redundancy and dynamic reconfiguration of the CGRA based on a library of configurations generated by a complete conception flow. This implemented flow relies on a flow to map a code represented as a Control and Data Flow Graph (CDFG) on the CGRA architecture by obtaining directly a large number of different configurations and allows to exploit the full potential of architecture.This work, which has been validated through experiments with applications in the field of signal and image processing, has been the subject of two publications in international conferences and of two patents.Que ce soit dans lâautomobile avec des contraintes thermiques ou dans lâaĂ©rospatial et le nuclĂ©aire soumis Ă des rayonnements ionisants, lâenvironnement entraĂźne lâapparition de fautes dans les systĂšmes Ă©lectroniques. Ces fautes peuvent ĂȘtre transitoires ou permanentes et vont induire des rĂ©sultats erronĂ©s inacceptables dans certains contextes applicatifs. Lâutilisation de composants dits « rad-hard » est parfois compromise par leurs coĂ»ts Ă©levĂ©s ou les difficultĂ©s dâapprovisionnement liĂ©s aux rĂšgles dâexportation.Cette thĂšse propose une approche conjointe matĂ©rielle et logicielle indĂ©pendante de la technologie dâintĂ©gration permettant dâutiliser des composants numĂ©riques programmables dans des environnements susceptibles de gĂ©nĂ©rer des fautes. Notre proposition comporte la dĂ©finition dâune Architecture Reconfigurable Ă Gros Grains (CGRA) capable dâexĂ©cuter des codes applicatifs complets mais aussi lâensemble des mĂ©canismes matĂ©riels et logiciels permettant de rendre cette architecture tolĂ©rante aux fautes. Ce rĂ©sultat est obtenu par lâassociation de redondance et de reconfiguration dynamique du CGRA en sâappuyant sur une banque de configurations gĂ©nĂ©rĂ©epar une chaĂźne de programmation complĂšte. Cette chaĂźne outillĂ©e repose sur un flot permettant de porter un code sous forme de Control and Data Flow Graph (CDFG) sur lâarchitecture en obtenant un grand nombre de configurations diffĂ©rentes et qui permet dâexploiter au mieux le potentiel de lâarchitecture.Les travaux, qui ont Ă©tĂ© validĂ©s aux travers dâexpĂ©riences sur des applications du domaine du traitement du signal et de lâimage, ont fait lâobjet de publications en confĂ©rences internationales et de dĂ©pĂŽts de brevets
E-diagnostic de processus physiques à base des méthodes de haute résolution Application : machines éoliennes
The expansion of systems using intelligent sensors has prompted the study of physical processes E-diagnosis based on high resolution methods. The automated control of modern wind machines requires proactive maintenance. We proposed several indicators measuring the performance level of a wireless protocol for routing data packets to the monitoring station. A study to design a diagnosis system entitled IESRCM for local or remote monitoring for the mentioned machines is achieved. A comparison has been realized to appreciate the performance of this system when it is integrated with GPRS or Wi-Max wireless modules. The obtained results by simulation using Proteus ISIS and OPNET software have favored the incorporation of Wi-Max module in the proposed system because its advantages over GPRS. The high resolution spectral estimation methods are effectively used for detecting electromechanical wind turbine faults. In front of the diversity of these methods, an investigation of each algorithm separately has been performed with a composite signal of stator current containing several types of defects and under different noisy environments. It was deduced in therein that the accuracy of the spectral estimation depends on the degree of the signal disturbance, the severity level of the faults, the frequency sampling and the number of data samples. The comparison with simulation in Matlab that we have made between these algorithms has proved the superiority of ESPRIT algorithm. However, this algorithm has a relatively large computing time and requires an important memory size to be executed. To overcome this problem, an improvement of ESPRIT-TLS technique has been proposed to make it applicable in real time. A new version of this method is developed in this thesis entitled Fast-ESPRIT. The proposed development is made by combining pass band recursive filtering technique IIR of Yule-Walker and decimation technique. The evaluation of the proposed technique for wind turbine fault detection of various types is performed. The analysis of the obtained results confirms that the Fast-ESPRIT algorithm provides a very satisfactory spectral accuracy in discriminating the studied faults harmonics. It resulted in a reduced complexity with an eligible ratio, a reduction of the required memory size for its implementation 5 times lower and a decrease of calculation time about 14,25 times less. This method provides better spectral resolution even in presence of a significant number of harmonics of different faults. However, this new method has some limitations because it does not recognize the type and the severity level of a detected fault. Therefore, another real time control approach has been proposed. It combines the developed Fast-ESPRIT method, the fault classification algorithm called CAFH and a fuzzy inference system interconnected with vibration sensors located on various wind turbine components. A new indicator of severity level for each studied fault type was formulated. It allows avoiding unnecessary alarms. Matlab simulation of this approach under four failure types with a noise shows that it provides a good robustness of faults classification.Lâexpansion des systĂšmes utilisant des capteurs intelligents a incitĂ© lâĂ©tude dâE-diagnostic de processus physiques Ă base des mĂ©thodes de haute rĂ©solution. Le contrĂŽle automatisĂ© des machines Ă©oliennes modernes nĂ©cessite la maintenance proactive. On a proposĂ© plusieurs indicateurs mesurant le niveau de performance dâun protocole dâacheminement sans fil des paquets de donnĂ©es vers la station de supervision. Une Ă©tude de conception dâun systĂšme de diagnostic IESRCM permettant la surveillance locale ou Ă distance des machines indiquĂ©es est rĂ©alisĂ©e. Une comparaison a Ă©tĂ© effectuĂ©e pour apprĂ©cier les performances de ce systĂšme lors de son intĂ©gration avec les modules sans fil GPRS ou Wi-Max. Les rĂ©sultats obtenus avec simulation sous Proteus ISIS et OPNET ont favorisĂ© lâincorporation du module Wi-Max dans le systĂšme proposĂ© en raison de ses avantages par rapport au GPRS. Les mĂ©thodes dâestimation spectrale Ă haute rĂ©solution sont efficacement utilisĂ©es pour la dĂ©tection de dĂ©fauts Ă©lectromĂ©caniques dâĂ©oliennes. Devant la diversitĂ© de ces mĂ©thodes, une investigation de chaque algorithme Ă part est rĂ©alisĂ©e avec un signal composite du courant statorique contenant plusieurs types de dĂ©fauts et sous un environnement diffĂ©remment bruitĂ©. On a dĂ©duit Ă cet Ă©gard que la prĂ©cision de lâestimation spectrale dĂ©pend du degrĂ© de perturbation du signal, du niveau de sĂ©vĂ©ritĂ© dâun dĂ©faut, de la frĂ©quence dâĂ©chantillonnage et du nombre dâĂ©chantillons de donnĂ©es. La comparaison avec simulation sous Matlab quâon a effectuĂ©e entre ces algorithmes a prouvĂ© la supĂ©rioritĂ© de lâalgorithme ESPRIT. Cependant, cet algorithme prĂ©sente un temps de calcul relativement grand et demande une taille mĂ©moire importante pour ĂȘtre exĂ©cutĂ©. Pour contourner cet obstacle, on a proposĂ© une amĂ©lioration de la technique ESPRIT-TLS pour la rendre applicable en temps rĂ©el. Une nouvelle version est dĂ©veloppĂ©e dans cette thĂšse intitulĂ©e Fast-ESPRIT. LâĂ©laboration envisagĂ©e est effectuĂ©e en combinant la technique de filtrage passe bande rĂ©cursif IIR de Yule-Walker et la technique de dĂ©cimation. LâĂ©valuation de la technique proposĂ©e dans la dĂ©tection de quatre types de dĂ©fauts dâune Ă©olienne est rĂ©alisĂ©e. Lâanalyse des rĂ©sultats obtenus confirme que lâalgorithme Fast-ESPRIT offre une prĂ©cision spectrale trĂšs satisfaisante dans la discrimination des harmoniques des dĂ©fauts Ă©tudiĂ©s. On a abouti Ă une complexitĂ© rĂ©duite avec un rapport admissible, Ă une rĂ©duction de lâespace mĂ©moire requis pour son exĂ©cution 5 fois infĂ©rieur et Ă la diminution du temps de calcul dâenviron 14,25 fois moins. Cette mĂ©thode offre une meilleure rĂ©solution mĂȘme en prĂ©sence dâun nombre important dâharmoniques de dĂ©fauts diffĂ©rents. Cependant, cette nouvelle mĂ©thode prĂ©sente quelques limitations puisquâelle ne permet pas de reconnaitre le type et le niveau de sĂ©vĂ©ritĂ© dâun dĂ©faut dĂ©tectĂ©. On a donc proposĂ© une autre approche de contrĂŽle en temps rĂ©el. Celle-ci combine la mĂ©thode Fast-ESPRIT dĂ©veloppĂ©e, lâalgorithme de classification de dĂ©fauts intitulĂ© CAFH et un systĂšme dâinfĂ©rence flou interconnectĂ© aux capteurs de vibration localisĂ©s sur les diffĂ©rentes composantes dâĂ©olienne. Un nouvel indicateur du niveau de sĂ©vĂ©ritĂ© de chaque type de dĂ©faut a Ă©tĂ© formulĂ©. Il permet dâĂ©viter les alarmes inutiles. La simulation sous Matlab de cette approche avec quatre types de dĂ©faillances en prĂ©sence dâun bruit montre quâelle offre une meilleure robustesse dans la classification des dĂ©fauts
Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management
Renewable energy and clean storage technologies are at the forefront of the worldâs fight against climate change, including the UN-led move towards a carbon-neutral society. Because these complex technologies require more âcriticalâ metals and elements than fossil fuel-based technologies, the demands for raw materials in their manufacturing are skyrocketing and are projected to continue to increase into the foreseeable future.With ore grades on a steep decline, huge amounts of low-grade ores will have to be mined and processed to satisfy the worldâs current and future demands for âcriticalâ metals and elements. Expansion of mining and mineral processing operations would mean more mining-related wastesâtailings, waste rocks and acid mine drainage (AMD)ânotorious for their devastating and long-term destructive impacts on the environment. This Special Issue explored repurposing/reprocessing of tailings and AMD treatment cost reduction as promising alternatives to manage mine wastes more sustainably. It also includes articles on the critical roles of redox conditions and galvanic interactions on mine waste stability, hydrogeochemical controls on waste rock weathering, and climate change impacts on AMD formation in closed mines
Reliability Abstracts and Technical Reviews January - December 1970
Reliability Abstracts and Technical Reviews is an abstract and critical analysis service covering published and report literature on reliability. The service is designed to provide information on theory and practice of reliability as applied to aerospace and an objective appraisal of the quality, significance, and applicability of the literature abstracted
Diachronie en langue de spécialité. Définition d'une méthode linguistique outillée pour repérer l'évolution des connaissances en corpus. Un exemple appliqué au domaine spatial.
Co-financĂ©e par le Centre National d'Ătudes Spatiales et le Centre National de la Recherche Scientifiques (Bourse de Docteur IngĂ©nieur CNRS/Entreprise)This doctoral dissertation explores the question of the diachronic dimension in terminology using a tool-based approach applied to a diachronic corpus. This study focuses on a request from the French National Space Agency (Cnes) where both knowledge and technology necessarily evolve over the course of âlong-termâ space projects (approx. 20 yrs.). This phenomenon can be tricky and a source of difficulties, such as poor communication with new coming engineers who arrive during the project or unconscious modifications of the meaning or forms of terms, etc. Learning how to identify this evolution is therefore of prime importance. Our research aims at defining a linguistic method to track down knowledge evolution within texts. This aim allows us to structure a triple point of view: a theoretical one, a methodological one and an applied one. To do so, this doctoral dissertation presents a description of four linguistic cues which can be semi-automatically identified in corpora to observe evolution: frequency, contexts of evolution, variants and syntactic dependencies. The cues are studied in two diachronic corpora from the Cnes: one corpus made up of three editions of a course on optics and optoelectronics (1994-2002) and one technical corpus composed of specification reports from the DORIS project (1989-2000). This context makes it possible to offer theoretical and methodological paths in textual terminology to track down, study and characterize the evolution that is likely to appear in specialized fields, especially within an environment that has been very little explored, i.e. short-term diachrony. The approach developed in this study also sheds light on the interpretation of corpus data, firstly, by combining linguistic cues in order to build up a reliable interpretation (or even a diagnosis) of the evolution through linguistic cues; secondly, by reflecting on the place and role of the experts in analyses and by analyst-expert dialoguing as a driving force in the co-construction of interpretations.Dans cette thĂšse nous abordons la question de la diachronie dans les langues de spĂ©cialitĂ© Ă travers la dĂ©finition d'une mĂ©thode linguistique pour repĂ©rer l'Ă©volution des connaissances en corpus. Cette recherche s'ancre dans une demande appliquĂ©e Ă©manant du Centre National d'Ătudes Spatiales (Cnes), oĂč la question de l'Ă©volution prend une dimension particuliĂšre dans le cadre de projets spatiaux dits « de longue durĂ©e » (~20 ans), au long desquels les connaissances impliquĂ©es Ă©voluent nĂ©cessairement. Ce phĂ©nomĂšne, inĂ©vitable mais parfois insidieux, est susceptible d'entraĂźner un certain nombre de difficultĂ©s telles qu'une mauvaise communication avec les ingĂ©nieurs qui arrivent en cours de projet, une modification non consciente du sens/de la forme des termes, etc. L'objectif est donc de proposer une mĂ©thode pour repĂ©rer cette Ă©volution, objectif qui permet d'articuler un triple regard sur la diachronie : un regard thĂ©orique, un regard descriptif et un regard appliquĂ©. Pour ce faire, cette thĂšse propose la description de quatre indices linguistiques repĂ©rables semi-automatiquement en corpus pour observer l'Ă©volution : la frĂ©quence, les contextes d'Ă©volution, les variantes et les dĂ©pendances syntaxiques. Ces indices sont explorĂ©s Ă partir de deux corpus diachroniques : trois Ă©ditions d'un cours d'optique et optoĂ©lectronique (1994-2002) et un corpus de rapports de spĂ©cification du projet spatial DORIS (1989-2000). Ce contexte permet de proposer des pistes thĂ©oriques et mĂ©thodologiques en terminologie textuelle pour repĂ©rer, Ă©tudier et caractĂ©riser l'Ă©volution susceptible de se manifester dans les domaines de spĂ©cialitĂ©, en particulier sur de trĂšs courts intervalles temporels. La dĂ©marche mise en place dans cette recherche permet Ă©galement d'alimenter la question de l'interprĂ©tation des donnĂ©es en corpus : tout d'abord Ă travers la combinaison d'indices comme moyen de construire une interprĂ©tation (voire un diagnostic) fiable de l'Ă©volution Ă partir d'indices linguistiques ; ensuite Ă travers la question du rĂŽle et de la place des experts dans l'analyse et du dialogue analyste/expert du domaine comme moteurs d'une co-construction de l'interprĂ©tation