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Статті в журналах з теми "Signaux Faible":
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Bouaiss, Karima, and Carine Girard-Guerraud. "Capital humain du dirigeant-entrepreneur et faillite des entreprises financées par ECF." Revue Française de Gestion 47, no. 299 (August 2021): 95–115. http://dx.doi.org/10.3166/rfg.2021.00556.
Анотація:
Le dirigeant-entrepreneur est l’acteur central dans la trajectoire de financement de l’entreprise. À partir de la théorie du signal, les auteures supposent que le capital humain de celui-ci émet des signaux pouvant affecter la probabilité de faillite de l’entreprise. Par l’étude de données portant sur 277 dirigeants-entrepreneurs financés par equity crowdfunding en France entre 2010 et 2018, elles montrent que les entreprises dirigées par des docteurs ont une probabilité de faire faillite plus faible alors qu’elle est plus élevée pour celles dirigées par d’anciens dirigeants.
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Boudarbat, Brahim, and Sonia Ines Gontero. "Offre de travail des femmes mariées immigrantes au Canada." Articles 84, no. 2 (February 25, 2009): 129–53. http://dx.doi.org/10.7202/000372ar.
Анотація:
Résumé Cette étude analyse l’offre de travail des femmes mariées selon le statut d’immigration au Canada. Nos résultats empiriques obtenus à l’aide des données du recensement canadien de 2001, indiquent que les femmes immigrantes ont un taux d’activité plus faible comparativement aux natives. Les immigrantes provenant d’Asie sont les moins susceptibles de participer au marché du travail alors que, parallèlement, cette région est devenue la source d’immigration la plus importante au Canada. Par ailleurs, nous trouvons que l’élasticité de l’offre de travail par rapport au salaire horaire est deux fois et demie plus élevée pour les natives comparativement aux immigrantes (0,18 contre 0,072). Ce faible degré de réponse des femmes immigrantes aux signaux du marché du travail, pourrait indiquer qu’elles ont moins de choix dans les faits à cause, peut-être, de contraintes culturelles quant à la position de la femme au sein du ménage, ou encore à cause des difficultés d’accès à l’emploi auxquelles font face les immigrantes. Enfin, nous trouvons que les immigrantes européennes ont une élasticité de l’offre de travail par rapport au salaire qui est légèrement supérieure à celle des autres immigrantes (0,082 contre 0,058), mais qui demeure significativement inférieure à celle des natives.
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Le Cam, Steven, Christophe Chollet, and Fabien Salzenstein. "Un arbre de Markov sélectif en fréquence pour la détection de signaux transitoires à faible rapport signal à bruit." Traitement du signal 27, no. 4-5 (October 28, 2010): 443–82. http://dx.doi.org/10.3166/ts.27.443-482.
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Gibbons, Cynthia, Rachel Schiffman, Holly Brophy-Herb, Hiram E. Fitzgerald, Mildred Omar, and Lorraine McKelvey. "Une étude exploratoire. Interaction entre les dyades mère-nourrisson et père-nourrisson chez les couples à faible revenu." Santé mentale au Québec 26, no. 1 (February 5, 2007): 101–17. http://dx.doi.org/10.7202/014513ar.
Анотація:
Résumé Vingt-neuf parents à faible revenu et leurs nourrissons ont participé à une recherche exploratoire portant sur les interactions parent-nourrisson et décrivant le niveau d'interactions, les similarités et les différences au sein des dyades mère-nourrisson et père-nourrisson. L'échelle de mesure Nursing Child Assessment Teaching Scale, un instrument d'observation standardisé de 73 items, a été utilisée pour mesurer les interactions. Les résultats ont montré que bien que la majorité (69%) des dyades parent-nourrisson n'ont pas démontré de comportements interactifs à risque, près de 31% de l'échantillon étaient désorganisés dans leurs interactions. De plus, les résultats ont démontré que bien que les deux parents étaient sensibles et répondaient aux signaux de leurs nourrissons, les mères étaient plus aptes que les pères à répondre à la détresse de leurs nourrissons alors que les nourrissons étaient plus clairs et répondaient mieux aux pères qu'aux mères. Avec cette information, les cliniciens et les chercheurs peuvent mieux comprendre les interactions au sein du contexte familial et renforcer les programmes d'intervention visant à maintenir et à améliorer les interactions parent-nourrisson.
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Allouis, Tristan, Jean-Stéphane Bailly, Yves Pastol, and Catherine Le Roux. "Utilisation conjointe de trains d'ondes lidar vert et infrarouge pour la bathymétrie des eaux de très faibles profondeurs." Revue Française de Photogrammétrie et de Télédétection, no. 213 (April 27, 2017): 33–42. http://dx.doi.org/10.52638/rfpt.2017.362.
Анотація:
La bathymétrie et la topographie des surfaces immergées sont des connaissances essentielles pour la gestion durabledes rivières et des espaces littoraux. Parmi les techniques permettant de les obtenir, le LiDAR bathymétrique apparaîtprometteur par sa capacité à relever de grandes surfaces en un temps limité, avec une forte résolution spatiale et demanière continue entre zones émergées et immergées.Bien que certaines études aient porté sur la précision de cette technique dans les zones côtières de profondeurmodérée, peu se sont intéressées aux eaux très peu profondes (< 3 m). Dans cette étude, une nouvelle méthode detraitement de formes d'ondes LiDAR pour les très faibles profondeurs est proposée. Cet algorithme s'appuie sur letraitement conjoint des trains d'ondes vert et proche-infrarouge (PIR). La densité et la précision des données résultantessur les eaux côtières très peu profondes sont ensuite analysées.Les résultats de ces développements et analyses sont présentés sur des données acquises sur le Golfe du Morbihan(France) par le Service Hydrographique et Océanographique de la Marine (SHOM) en 2005 avec un système SHOALSqui fournit les formes d'ondes Raman, PIR et vert. Ce travail met l'accent sur la comparaison de la qualité entre lesdonnées bathymétriques livrées issues du traitement des signaux par l'opérateur et celles issues de l'algorithme detraitement proposé. Pour la validation des résultats, une méthode spécifique est utilisée ici afin de faciliter lacomparaison de mesures altimétriques réalisées entre des points GPS de référence et des empreintes LiDAR (diamètrede l'ordre de 2 m). Dans les très faibles profondeurs d'eau, l'algorithme proposé extrait 41% de mesuressupplémentaires par rapport aux données livrées, avec un biais de mesure comparable (environ 5 cm) et un écart-typedes erreurs plus faible (26,1 cm contre 41,1 cm). 55% de ces mesures supplémentaires sont situés à une profondeurcomprise entre 1,5 m et 2 m. De plus, l'algorithme proposé améliore la profondeur minimale détectable de 80 cm parrapport aux données livrées (1 m contre 1,8 m).
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Vautrin, Denis, Irmela Zentner, Guy D’Urso, Géry Hachet, Christophe Vergniault, and Dimitri Mercadier. "Démarche de qualification de l’utilisation de la méthode MASW sur les digues par mesures en environnement contrôlé et simulations pour évaluer l’influence de la géométrie 3D des ouvrages." Revue Française de Géotechnique, no. 178 (2024): 2. http://dx.doi.org/10.1051/geotech/2024005.
Анотація:
Les digues de protection contre les inondations peuvent faire l’objet de campagnes de reconnaissance dans le but d’identifier d’éventuelles zones de faiblesse et de prévenir tout risque de défaillance. La méthode Multi-channel Analysis of Surface Waves (MASW), non invasive et à faible coût, offre un complément intéressant aux sondages géotechniques. Elle est notamment utile pour les ouvrages de grand linéaire car elle est employable en mode « grand rendement ». Cependant, la méthode MASW repose sur une hypothèse de milieu 1D stratifié, c’est-à-dire que la surface du sol ainsi que les interfaces entre les différentes couches de sol sont supposées horizontales. Cela n’est a priori pas compatible avec la topographie 3D de l’ouvrage. Nous avons réalisé une étude de sensibilité des résultats de MASW à la géométrie 3D d’une digue en nous appuyant à la fois sur des mesures expérimentales et sur des simulations. L’ouvrage considéré est une maquette de digue à l’échelle 1. Dans un premier temps, nous avons proposé une méthodologie de simulation permettant de reproduire numériquement la propagation d’une onde sismique en 3D pour la configuration de la maquette, et nous avons validé ce modèle par comparaison entre signaux numériques et acquisitions réelles. Dans un second temps, nous avons considéré différentes configurations de simulation dans le but d’évaluer l’influence de la géométrie 3D de l’ouvrage. D’après les résultats obtenus, la géométrie 3D de la digue entraîne une sous-estimation de la profondeur de l’interface entre la digue et le sol. En revanche, son influence sur l’estimation des caractéristiques des couches est négligeable. Ces résultats sont en accord avec le retour d’expérience terrain d’EDF. D’autres limites restent à approfondir par de nouvelles simulations, en considérant des ouvrages de plus grandes dimensions et à géométries plus complexes. De plus, l’exploitation de la maquette de digue se poursuivra avec la mise en œuvre de méthodes électriques, et avec des travaux sur les méthodes de fusion de données.
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Minaker, Leia M., Meghan Lynch, Brian E. Cook, and Catherine L. Mah. "Analyse de données sur les ventes lors d'une intervention axée sur un dépanneur santé de Toronto : le projet FRESH sur l'environnement de la vente d’aliments au détail comme déterminant de la santé." Promotion de la santé et prévention des maladies chroniques au Canada 37, no. 10 (October 2017): 383–91. http://dx.doi.org/10.24095/hpcdp.37.10.04f.
Анотація:
Introduction Les interventions en santé de la population dans le secteur de l’alimentation de détail, comme celles réalisées dans les dépanneurs, visent à transformer le type de signaux envoyés aux consommateurs afin qu'ils choisissent des aliments plus sains. Peu de recherches abordent les aspects financiers des interventions réalisées dans le milieu de la vente au détail, en particulier les mesures de résultat comme les ventes en magasin, pourtant au centre du processus décisionnel de la vente au détail. Cette étude examine l'évolution des ventes en magasin et les ventes par catégories de produits dans le cadre d’une intervention axée sur un dépanneur santé situé dans un quartier à faible revenu de Toronto (Ontario). Méthodologie Les données sur les ventes effectuées entre août 2014 et avril 2015 ont été regroupées par catégories de produits et par jour. Nous avons utilisé des tableaux croisés dynamiques Excel afin de résumer et de présenter visuellement les données sur ces ventes. Nous avons mené des tests t afin d’étudier les différences au niveau des ventes de chaque catégorie de produits en fonction des jours de vente « de pointe » (jours d’affluence) par rapport aux autres jours de vente. Résultats Les ventes globales du magasin culminaient les derniers jours de chaque mois, soit à la période à laquelle les prestations d’assistance sociale sont versées. La hausse des revenus lors des jours de pointe était principalement imputable aux ventes de laissez-passer de transports en commun. La moyenne des ventes de collations non nutritives et de cigarettes était légèrement plus élevée lors des jours de pointe par rapport aux autres jours. Les stratégies novatrices employées pour augmenter les ventes de fruits et légumes frais ont semblé accroître considérablement les revenus générés par ces catégories de produits. Conclusion Les données sur les ventes en magasin constituent un paramètre important de mesure du succès des interventions en environnement alimentaire. De plus, les prises de décision des détaillants fondé sur ces données peuvent se révéler déterminantes lors de l’adaptation des interventions. Les responsables des recherches et des interventions futures devraient envisager d’établir des partenariats et d’utiliser d'autres indicateurs de rendement lors des interventions ciblant l'environnement de la vente au détail d’aliments dans divers contextes canadiens.
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Lhomme, Quentin. "NUNKI : détecter les signaux faibles." Servir N° 519, no. 1 (February 27, 2023): 62–64. http://dx.doi.org/10.3917/servir.519.0062.
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Texier, Bruno. "Tom Morisse, détecteur de signaux faibles." Archimag N°313, no. 3 (April 1, 2018): 43. http://dx.doi.org/10.3917/arma.313.0043.
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Sylvestre, Guillaume. "Détecter des signaux faibles en cartographiant des tweets." I2D - Information, données & documents 53, no. 3 (2016): 12. http://dx.doi.org/10.3917/i2d.163.0012.
Дисертації з теми "Signaux Faible":
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Le, Pelleter Tugdual. "Méthode de discrétisation adaptée à une logique événementielle pour l'utra-faible consommation : application à la reconnaissance de signaux physiologiques." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT043/document.
Анотація:
Les systèmes embarqués mobiles font partis intégrante de notre quotidien. Afin de les rendre plus adaptésaux usages, ils ont été miniaturisés et leur autonomie a été augmentée, parfois de façon très considérable.Toutefois, les propositions d’amélioration butent désormais sur les possibilités de la technologie des circuitsintégrés. Pour aller plus loin, il faut donc envisager de repenser la chaîne de traitement du signal afin deréduire la consommation de ces dispositifs. Cette thèse développe une approche originale pour exploiterefficacement l’échantillonnage par traversée de niveaux d’une part et, d’autre part, associe cet échantillonnageà une logique évènementielle afin de réduire drastiquement la consommation d’énergie des systèmesintégrés autonomes. Une méthode de discrétisation adaptée à une application de reconnaissance de signauxphysiologiques, utilisée comme exemple dans cette thèse, y est présentée. Un premier prototype en logiqueévènementielle (asynchrone) sur circuit FPGA a permis de valider cette stratégie et de démontrer les bénéficesde cet échantillonnage dédié en termes de réduction de l’activité par rapport à un échantillonnage uniforme.Un second prototype en logique asynchrone et conçu en technologie CMOS AMS 0.35 μm a permis de validerpar simulation électrique un gain extrêmement important sur la consommation électrique du dispositifOur everyday life is highly dependent on mobile embedded systems. In order to make them suitable to differentapplications, they have underwent size reduction and lifetime extension. However, these improvementsare currently limited by the possibilities of the integrated circuits technologies. In order to push back theboundaries, it is necessary to reconsider the whole digital signal processing chain from scratch to sustain thepower consumption reduction in this kind of system. This work develops on the first hand a strategy thatsmartly uses the level-crossing sampling scheme and on the other combines this sampling method with eventlogicto highly reduce the power consumption in mobile embedded systems. A discretisation method adaptedto the recognition of physiological patterns application is described. A first event-logic (asynchronous) prototypeimplemented on FPGA proved the potential benefits that an adapted sampling scheme could offersto reduce activity compared to a uniform sampling scheme. Electrical simulations performed on a secondprototype, also designed in asynchronous logic, with CMOS AMS 0.35 μm technology, validated a high gainin power consumption
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Le, Pas de Sécheval Helman. "Traitement des signaux optiques a tres faible niveau de puissance : application a la detection heterodyne traitement de la phase." Paris 6, 1992. http://www.theses.fr/1992PA066542.
Анотація:
Un des problemes theoriques les plus importants des communications optiques quantiques a detection heterodyne est la definition d'un operateur obeissant aux lois de la mecanique quantique. Le present memoire est consacre a l'analyse des differentes approches de cet operateur. La premiere partie est consacree a l'expose des divers criteres permettant d'optimiser les performances d'un recepteur: probabilite d'erreur, capacite, debit critique. Les differents recepteurs (direct, homodyne et heterodyne) sont passes en revue et il est montre qu'ils ne sont tous que sous-optimaux. Dans la deuxieme partie, la detection directe (comptage du nombre de photons et mesure de l'intervalle de temps separant deux photons) pour un canal binaire est etudiee en detail dans deux cas: un processus de poisson issu d'un signal sans memoire dans un canal faiblement bruite; des processus de poisson composes (groupement et antigroupement) dans un canal sans bruit. Il est montre qu'une description approfondie de la lumiere comporte necessairement des aspects non classiques. La derniere partie est consacree a un expose complet des resultats recents demontres pour l'operateur de phase et il est montre comment l'extension non-standard de l'espace de hilbert de l'optique quantique permet la definition d'un operateur de phase auto-adjoint
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Nicodeme, Marc. "Identifiabilité des signaux parcimonieux structurés et solutions algorithmiques associées : application à la reconstruction tomographique à faible nombre de vues." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0096/document.
Анотація:
Cette thèse étudie différents problèmes de minimisations avec des fonctions de régularisations qui promeuvent la parcimonie. Plus précisément, on souhaite reconstruire une image, que l'on suppose parcimonieuse et qui a subit une transformation après un opérateur linéaire, à l'aide de problèmes de minimisations. Dans ce manuscrit, on s'intéressera plus particulièrement à la minimisation l1 synthèse, analyse et bloc qui sont très utilisées pour reconstruction une image que l'on sait parcimonieuse. Ces minimisations produisent en pratique des résultats convaincants qui n'ont été compris théoriquement que récemment. Les différents travaux sur le sujet mettent en évidence le rôle d'un vecteur particulier appelé certificat dual. L'existence d'un certificat dual permet à la fois d'assurer la reconstruction exacte d'une image dans le cas où il n'y a pas de perturbations et d'estimer l'erreur de la reconstruction en présence de perturbations. Dans nos travaux, nous allons introduire l'existence d'un certifical dual optimal pour la minimisation l1 synthèse qui minimisent l'erreur de reconstruction. Ces résultats ayant une forte interprétation géométrique, nous avons développé un critère identifiabilité, c'est à dire que ce critère assure que l'image recherchée est l'unique solution du problème de minimisation. Ce critère permet d'étendre nos travaux à la minimisation l1 analyse, l1 bloc et à d'autres casThis thesis studies different minimization problems with sparses based regularization. More precisely, we want to reconstruct a sparses image, which undergone a linear transformation, with minimization problems. In this manuscript, we will be focused on l1 synthesis, analysis and block minimization which are widely used in sparse approximations. These problems offer competitive results which are theorietical understood only recntly. Different studies on the subject emphasized the contribution of a particular vector called dual certificate. The existence of this dual certificate allows simultaneously to guarantee the exact recovey of an image in noiseless case and to estimate the noise robustness in noisy case. In this work, we introduce eth existence of an optimal dual certificate for the l1 synthesis minimization which minimizes the reconstruction error. As those results have a strong geometrical interpretation, we develop an identifiability criterion which ensures the uniqueness of a solution. This criterion generalizes the work on l1 synthesis minimization tothe analysis case, block case and others
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Brizon, Ambre. "Compréhension et gestion des signaux faibles dans le domaine de la santé-sécurité." Phd thesis, École Nationale Supérieure des Mines de Paris, 2009. http://tel.archives-ouvertes.fr/tel-00403623.
Анотація:
Ce travail de recherche était basé dans le laboratoire CRC des Mines ParisTech, financé par la FonCSI et avait pour terrain de recherche sanofi-aventis (la direction centrale HSE et les sites pharmaceutiques core solid français). Le but de ce travail était de comprendre et d'aider à mieux gérer les signaux faibles sur nos terrains de recherche, dans le domaine des risques d'accidents de travail et de maladies professionnelles. Cette thèse propose une vision holistique des signaux faibles en les observant tout au long de leur vie, au travers des différents groupes d'acteurs, de la hiérarchie et des outils. Les méthodes de travail sont basées sur la grounded theory, en extrayant du terrain le modèle que nous proposons et en travaillant à base d'études de cas. Nous avons donc extrait un modèle permettant de mieux définir les signaux faibles : le « modèle DPTP » : un signal faible est un signal pouvant annoncer un évènement majeur (accident majeur, accident du travail ou maladie professionnelle) et restant faible aux différentes étapes de sa vie (détection, pertinence, transmission, priorisation). Pour chacune des étapes de notre modèle nous avons cherché dans la littérature quelles étaient les connaissances nécessaires à l'avancement de notre travail. Ensuite, nous sommes retournés sur le terrain afin de mener différentes études de cas pour valider et préciser chacune de ces étapes. Au terme de ce travail, nous pouvons proposer le modèle DPTP comme un modèle permettant l'aide à la gestion des signaux faibles.
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Pelissier, Michaël. "Développement d'architecture et de fonctions RF avancées pour la réception de signaux Ultra Large Bande dans les applications à basse consommation." Grenoble INPG, 2006. http://www.theses.fr/2006INPG0153.
Анотація:
En dehors des applications à haut débit, l'Ultra Large Bande (ULB) offre également un potentiel important pour des applications plus bas débit dont la principale contrainte est la consommation. La thèse présente la réalisation de fonctions critiques du front-end RF d'une architecture de réception ULB innovante dédiée à ces applications. Dans un premier temps, le contexte général associé à l'ULB et les différents types de récepteur de signaux impulsionnels sont présentés. Deux points bloquants sont mis en évidence: la consommation élevée des étages de gain et la difficulté d'atteindre une bonne résolution temporelle à faible coût. Aussi le premier axe de travail a consisté à réaliser un LNA faible consommation basé sur une solution d'amplification adaptée à la forme du signal. Dans un deuxième temps nous avons proposé une nouvelle architecture de récepteur ULB à base de super-régénération. Les résultats de mesures du circuit réalisé en technologie CMOS O,13flm valident le conceptExcept high data rate applications, Ultra Wide Band (UWB) shows potential great interest for low date rate systems, in which, major constraints rely on power consumption. This thesis presents the development of critical blocs for RF receiver front end of an innovative architecture dedicated to the latter applications. First, the general context of UWB, and several pulse signal receivers are reminded. Two critical points are highlighted: the excessive power consumption of the gain stages and the difficulty to achieve precise resolution in time do main while keeping low cost devices. Thus, first work objective consisted in the development of low power LNA based on matched amplification to the signal shape. Then, we proposed a novel UWB receiver architecture based on super-regeneration. Measurements results of the chip fabricated in 0,13 flm CMOS process validate the concept
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Murgia, Carlo. "Codage haute qualité des signaux de parole (20 Hz - 15 kHz) à très faible retard et au débit de 64 kbit/s." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0187.
Анотація:
Cette etude a pour objectif l'elaboration d'algorithmes performants de compression des signaux audio (parole et musique) de la bande fm (20 hz - 15 khz) a tres faible retard et au debit de 64 kbit/s. Nous avons choisi la technique ld-celp comme algorithme de base. Ce codeur a initialement ete concu pour la quantification a tres faible retard des signaux de parole de la bande telephonique (300-3400 hz) et standardise a l'itu-t sous le sigle g. 728. Une partie de notre travail a consiste a etendre cet algorithme a la bande fm en optimisant sa structure et en exploitant au mieux les proprietes du systeme perceptif humain. Ensuite, en nous basant sur cette technique, nous avons mis au point d'autres schemas de compression de haute qualite et a faible retard. Dans un premier temps nous avons modifie l'algorithme du g. 728 pour l'adapter a la bande fm. Pour ce faire, nous avons mis au point une procedure et des outils de test permettant d'optimiser les parametres de cet algorithme au sens d'un critere de distorsion perceptuelle. En particulier, nous avons developpe un algorithme d'evaluation de la qualite subjective denomme mpeq : mesure perceptuelle d'evaluation de la qualite. Grace a ces optimisations nous avons pu atteindre une bonne qualite des signaux codes. Cependant, la quasi-transparence ne peut etre atteinte que par l'introduction d'algorithmes de mise en forme optimale du bruit de quantification. Nous avons ainsi propose de nouveaux algorithmes bases sur la modelisation par prediction lineaire de la courbe de masquage. Dans un second temps, nous avons etudie des codeurs permettant de reduire la complexite sans perte significative de qualite. Nous avons exploite l'utilisation des dictionnaires ternaires algebriques et propose un codeur predictif adaptatif a faible retard base sur la quantification vectorielle gain-forme. Ces techniques de compression permettent une reduction de la complexite allant jusqu'a 30% tout en garantissant une qualite satisfaisante pour la parole et la musique. Les algorithmes proposes ont ete evalues par des tests d'ecoutes formels. La qualite des signaux codes par nos codeurs est comparable a celle du standard mpeg layer ii et significativement superieure a celle du standard mpeg layer i et ceci pour un retard de seulement 0,15 ms contre un retard de 35 ms pour les codeurs mpeg.
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Ferreira, Esteves Paulo Alexandre. "Techniques d'acquisition à haute sensibilité des signaux GNSS." Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0016/document.
Анотація:
Les systèmes de navigation par satellite (GNSS) font partie de notre quotidien. On peut présentement les trouver dans un ensemble d’applications. Avec les nouveaux besoins, des nouveaux enjeux sont aussi apparus : le traitement du signal dans les environnements urbains est extrêmement complexe. Dans cette thèse, le traitement des signaux GNSS à faible puissance est abordé, en particulier dans la première phase du traitement, nommé acquisition de signal. Le premier axe de rechercheporte sur l’analyse et la compensation de l’effet Doppler dans l’acquisition. Le décalage Doppler perçu par l’utilisateur est un des paramètres principaux pour la configuration du module d’acquisition. Dans cette étude, des solutions sont proposées pour trouver le meilleur compromis sensibilité-complexité propre à l’acquisition. En deuxième axe, la caractérisation des détecteurs différentiels est abordée, en particulier la quantification de sa sensibilité. Pour l’acquisition des signaux faibles, après une première phase d’intégration cohérente, il faut passer par une intégration «postcohérente» (noncohérente ou différentielle.) L’analyse exécutée ici permet de meilleur identifier le meilleur choix entre les deux possibilités. Le troisième axe de recherche est consacré à la méthode de Détection Collective (CD), une innovation qui fait l’acquisition simultanée de tous les signaux visible par le récepteur. Plusieurs analyses sont réalisées incluant l’amélioration de la procédure de recherche de la CD, et l’hybridisation avec l’acquisition standard. Enfin on effectuel’analyse de la CD dans un contexte multi-constellation, en utilisant simultanément des vrais signaux GPS et GalileoSatellite navigation (GNSS) is a constant in our days. The number of applications that depend on it is already remarkable and is constantly increasing. With new applications, new challenges have also risen: much of the new demand for signals comes from urban areas where GNSS signal processing is highly complex. In this thesis the issue of weak GNSS signal processing is addressed, in particular at the first phase of the receiver processing, known as signal acquisition. The first axe of research pursued deals with the analysis and compensation of the Doppler effect in acquisition. The Doppler shift that is experienced by a user is one of the main design drivers for the acquisitionmodule and solutions are proposed to improve the sensitivity-complexity trade-off typical of the acquisition process. The second axe of research deals with the characterization of differential GNSS detectors. After a first step of coherent integration, transition to post coherent (noncoherent or differential) integration is required for acquiring weak signals. The quantification of the sensitivity of differential detectors was not found in literature and is the objective of this part of the research. Finally, the third axe of research is devoted to multi-constellation Collective Detection (CD). CD is an innovative approach for the simultaneous processing of all signals in view. Severalissues related to CD are addressed, including the improvement of the CD search process and the hybridization with standard acquisition. Finally, the application of this methodology in the context of a multi-constellation receiver is also addressed, by processing simultaneously real GPS and Galileo signals
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Rarbi, Fatah-Ellah. "Conception d’un convertisseur analogique numérique pipeline de grande dynamique et de faible consommation pour le codage des signaux de détecteurs à forte granularité." Grenoble INPG, 2010. http://www.theses.fr/2010INPG0128.
Анотація:
L’objectif de cette thèse est la conception de convertisseur analogique-numérique (CAN) de type pipeline pour le codage des signaux de détecteurs à forte granularité. Au cours de cette thèse, nous avons développé un modèle pour une étude approfondie des différentes sources d’erreurs et leurs conséquences sur les caractéristiques du convertisseur pipeline 12 bits à 25 MHz. Nous avons également finalisé un prototype aux limites de la technologie choisie par la collaboration CALICE dans le cadre du projet ILC. Une nouvelle architecture de CAN pipeline avec un premier étage MDAC multi-bits incluant une structure DEM a été conçue pour alles au-delà des limites de la technologie. Enfin, en parallèle avec les travaux de conception, un effort a été consacré au développement de programmes de test pour la caractérisation des différents prototypes de convertisseur A/N. Nous expliquons les résultats de tests de trois prototypes de CAN pipeline 12 bits réalisés au cours de ces trois années de thèse. Une comparaison est faite par rapport à d’autres études en cours pour le calorimètre électromagnétique d’ILDThe objective of this thesis is the design of a low power and high dynamic pipeline ADC for high granularity detector read-out. In this thesis, we developed a model for further study of different sources of errors and their consequences on the characteristics of a 12-bit pipeline converter. We also completed an ADC prototype in the limit of technology selected by the CALICE collaboration within the ILC project. New pipeline ADC architecture with a multi-bit MDAC first stage structure including a DEM has been designed to go beyong the limits of technology. Finally, in parallel with the design work, an effort has been devoted to developing test programs for the characterization of different prototypes of A/D converters. We explain the results of testing three prototype 12-bit pipeline ADC achieved during these three years of thesis. A comparison is made with respect to other ongoing studies for the electromagnetic calorimeter of ILD
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Udupa, Pramod. "Algorithmes parallèles et architectures évolutives de faible complexité pour systèmes optiques OFDM cohérents temps réel." Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S039/document.
Анотація:
Dans cette thèse, des algorithmes à faible complexité et des architectures parallèles et efficaces sont explorés pour les systèmes CO-OFDM. Tout d'abord, des algorithmes de faible complexité pour la synchronisation et l'estimation du décalage en fréquence en présence d'un canal dispersif sont étudiés. Un nouvel algorithme de synchronisation temporelle à faible complexité qui peut résister à grande quantité de retard dispersif est proposé et comparé par rapport aux propositions antérieures. Ensuite, le problème de la réalisation d'une architecture parallèle à faible coût est étudié et une architecture parallèle générique et évolutive qui peut être utilisée pour réaliser tout type d'algorithme d'auto-corrélation est proposé. Cette architecture est ensuite étendue pour gérer plusieurs échantillons issus du convertisseur analogique/numérique (ADC) en parallèle et fournir une sortie qui suive la fréquence des ADC. L'évolutivité de l'architecture pour un nombre plus élevé de sorties en parallèle et les différents types d'algorithmes d'auto-corrélation sont explorés. Une approche d'adéquation algorithme-architecture est ensuite appliquée à l'ensemble de la chaîne de l'émetteur-récepteur CO-OFDM. Du côté de l'émetteur, un algorithme IFFT à radix-22 est choisi pour et une architecture parallèle Multipath Delay Commutator (MDC). Feed-forward (FF) est choisie car elle consomme moins de ressources par rapport aux architectures MDC-FF en radix-2/4. Au niveau du récepteur, un algorithme efficace pour l'estimation du Integer CFO est adopté et implémenté de façon optimisée sans l'utilisation de multiplicateurs complexes. Une réduction de la complexité matérielle est obtenue grâce à la conception d'architectures efficaces pour la synchronisation temporelle, la FFT et l'estimation du CFO. Une exploration du compromis entre la précision des calculs en virgule fixe et la complexité du matériel est réalisée pour la chaîne complète de l'émetteur- récepteur, de façon à trouver des points de fonctionnement qui n'affectent pas le taux d'erreur binaire (TEB) de manière significative. Les algorithmes proposés sont validés à l'aide d'une part d'expériences off-line en utilisant un générateur AWG (arbitrary wave- form generator) à l'émetteur et un oscilloscope numérique à mémoire (DSO) en sortie de la détection cohérente au récepteur, et d'autre part un émetteur-récepteur temps-réel basé sur des plateformes FPGA et des convertisseurs numériques. Le TEB est utilisé pour montrer la validité du système intégré et en donner les performancesIn this thesis, low-complexity algorithms and architectures for CO-OFDM systems are explored. First, low-complexity algorithms for estimation of timing and carrier frequency offset (CFO) in dispersive channel are studied. A novel low-complexity timing synchro- nization algorithm, which can withstand large amount of dispersive delay, is proposed and compared with previous proposals. Then, the problem of realization of low-complexity parallel architecture is studied. A generalized scalable parallel architecture, which can be used to realize any auto-correlation algorithm, is proposed. It is then extended to handle multiple parallel samples from ADC and provide outputs, which can match the input ADC rate. The scalability of the architecture for higher number of parallel outputs and different kinds of auto-correlation algorithms is explored. An algorithm-architecture approach is then applied to the entire CO-OFDM transceiver chain. At the transmitter side, radix-22 algorithm for IFFT is chosen and parallel Mul- tipath Delay Commutator (MDC) Feed-forward (FF) architecture is designed which con- sumes lesser resources compared to MDC FF architectures of radix-2/4. At the receiver side, efficient algorithm for Integer CFO estimation is adopted and efficiently realized with- out the use of complex multipliers. Reduction in complexity is achieved due to efficient architectures for timing synchronization, FFT and Integer CFO estimation. Fixed-point analysis for the entire transceiver chain is done to find fixed-point sensitive blocks, which affect bit error rate (BER) significantly. The algorithms proposed are validated using opti- cal experiments by the help of arbitrary waveform generator (AWG) at the transmitter and digital storage oscilloscope (DSO) and Matlab at the receiver. BER plots are used to show the validity of the system built. Hardware implementation of the proposed synchronization algorithm is validated using real-time FPGA platform
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Grégoire, Marie-Claude. "Reconstruction d'images cardiaques dynamiques synchronisées à l'ECG par maximum de vraisemblance sur les signaux obtenus à faible taux de comptage avec une gamma-caméra." Compiègne, 1989. http://www.theses.fr/1989COMPD190.
Анотація:
Une méthode de traitement des études cardiaques dynamiques permettant la prise en compte simultanée de toutes les informations spatiales et temporelles, afin d'effectuer un lissage global, a été proposée. Elle repose sur l'utilisation de l'estimation bayésienne, introduisant une loi à priori du type loi de Gibbs. Une étude comparative sur simulations à faible taux de comptage entre cette méthode et diverses méthodes classiques a permis d'une part de révéler les avantages liés à l'utilisation de toute l'information temporelle disponible, d'autre part d'améliorer la qualité des résultats cliniques courantsTo do a global smoothing, a processing technic of dynamic cardiac studies has been suggested, allowing the simultaneous integration of all the spatial and temporal informations. This technic uses a bayesian estimation, therefore introducing an a priori law of Gibbs. A comparative study was done on low-count simulations, using this method and other classical methods. It has shown the advantages of using all the available temporal informations, and has increased the quality of current clinical results
Книги з теми "Signaux Faible":
1
Rayne, Alexandre. Prévenir les ruptures stratégiques: Du bon usage des signaux faibles. Paris: L'Harmattan, 2008.
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K, Kokula Krishna Hari, ed. Method to Provide Mobile Signal when the Network Provider Has Failed. Chennai, India: Association of Scientists, Developers and Faculties, 2016.
3
Pace, Phillip E. Detecting and classifying low probability of intercept radar. 2nd ed. Boston: Artech House, 2009.
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Pace, Phillip E. Detecting and classifying low probability of intercept radar. 2nd ed. Boston: Artech House, 2009.
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Pace, Phillip E. Detecting and classifying low probability of intercept radar. Boston, MA: Artech House, 2004.
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Pace, Phillip E. Detecting and classifying low probability of intercept radar. 2nd ed. Boston: Artech House, 2009.
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Pace, Phillip E. Detecting and classifying low probability of intercept radar. 2nd ed. Boston: Artech House, 2009.
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Lynch, David. Introduction to RF stealth. Raleigh, NC: SciTech Pub., 2004.
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Wheeler, Nicholas J. USA–Iran, 2009–2010. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199696475.003.0009.
Анотація:
This chapter examines the attempts by the first Obama Administration to reach out to Iran in an effort to build trust. It traces the failure of Obama’s diplomatic efforts to secure any reciprocation from Iranian leaders. The lack of reciprocation shows the problem of accurate signal interpretation when there is no trust. It focuses on the negotiations in 2009–10 over limiting Iran’s supply of nuclear fuel in return for refuelling the Tehran Research Reactor. The chapter argues these negotiations failed because of the lack of trust. What makes this case so important is that there was no face-to-face interaction, which this book argues is critical to the development of interpersonal trust and accurate signal interpretation.
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Ferris, John. Intelligence in War. Oxford University Press, 2018. http://dx.doi.org/10.1093/acrefore/9780190846626.013.405.
Анотація:
A large literature has emerged on intelligence and war which integrates the topics and techniques of two disciplines: strategic studies and military history. The literature on intelligence and war is divided into theory and strategy; command, control, communications, and intelligence (C3I); sources; military estimates in peace; deception; conventional operations; strike; and counter-insurgency and guerilla warfare. Sun Tzu treats intelligence as central to all forms of power politics, and even defines strategy and warfare as “the way of deception.” On the other hand, C3I combines signals and data processing technology, command as thought, process and action, the training of people, and individual and bureaucratic modes of learning. Since 1914, the power of secret sources has risen dramatically in peace and war, revolutionizing the value of intelligence for operations, especially at sea. The strongest area in this study is signals intelligence. Meanwhile, the relationship of intelligence with war, and with power politics, overlaps on the matter of military estimates during peacetime. The literature on operational intelligence is strongest on World War II. However, analysts have particularly failed to differentiate the effect of intelligence on operations, from that on a key element of military power since 1914: strike warfare. In counter-insurgency, many types and levels of war and intelligence overlap, which include guerillas, conventional and strike forces, and politics in villages and capitals.
Частини книг з теми "Signaux Faible":
1
Dolbeer, Richard A., Paul P. Woronecki, and Roger W. Bullard. "Visual Cue Fails to Enhance Bird Repellency of Methiocarb in Ripening Sorghum." In Chemical Signals in Vertebrates 6, 323–30. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4757-9655-1_52.
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Zhang, Zhenya, Jie An, Paolo Arcaini, and Ichiro Hasuo. "Online Causation Monitoring of Signal Temporal Logic." In Computer Aided Verification, 62–84. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-37706-8_4.
Анотація:
AbstractOnline monitoring is an effective validation approach for hybrid systems, that, at runtime, checks whether the (partial) signals of a system satisfy a specification in, e.g., Signal Temporal Logic (STL). The classic STL monitoring is performed by computing a robustness interval that specifies, at each instant, how far the monitored signals are from violating and satisfying the specification. However, since a robustness interval monotonically shrinks during monitoring, classic online monitors may fail in reporting new violations or in precisely describing the system evolution at the current instant. In this paper, we tackle these issues by considering the causation of violation or satisfaction, instead of directly using the robustness. We first introduce a Boolean causation monitor that decides whether each instant is relevant to the violation or satisfaction of the specification. We then extend this monitor to a quantitative causation monitor that tells how far an instant is from being relevant to the violation or satisfaction. We further show that classic monitors can be derived from our proposed ones. Experimental results show that the two proposed monitors are able to provide more detailed information about system evolution, without requiring a significantly higher monitoring cost.
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Kelso, Elizabeth J., Robert F. Geraghty, Barbara J. McDermott, Elisabeth R. Trimble, D. Paul Nicholls, and Bernard Silke. "Mechanical effects of ET-1 in cardiomyocytes isolated from normal and heart-failed rabbits." In Biochemistry of Signal Transduction in Myocardium, 149–55. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-1275-8_19.
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Panesso, M., M. Ettrichrätz, S. Gebhardt, O. Georgi, C. Rüger, M. Gnauck, and W. G. Drossel. "Design and Characterization of Piezoceramic Thick Film Sensor for Measuring Cutting Forces in Turning Processes." In Lecture Notes in Mechanical Engineering, 30–39. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-28839-5_4.
Анотація:
AbstractCutting forces in turning processes usually correlate with tool conditions. For this reason, the acquisition of force signals is of key importance for monitoring purposes. Despite the robustness of current piezoelectric measuring platforms, their large weight ratio relative to standalone tool-holder systems limits their effective usable bandwidth for analyzing force signals. Further limitations include high costs and lack of flexibility for general purpose turning operations. Due to this, such systems fail to find acceptance in practical applications and are mainly limited to research activities. To improve these aspects, this work investigates the use of an alternative integration concept using a piezoceramic thick film sensor for performing near-process cutting force measurements at the tool-holder. The charge output of the sensor was estimated using a coupled structural-piezoelectric simulation for its design. The modelled prototype was assembled and characterized by means of a static calibration and an impact hammer test. Following these, a first implementation of the system under dry cutting conditions took place.
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Faessler, R., K. Schauenstein, G. Kroemer, and G. Wick. "Immune Signals Fail to Elict Endocrine Responses in the Obese Strain (OS) of Chickens with Hashimoto-Like Autoimmune Thyroiditis." In Thyroid Autoimmunity, 493–95. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4613-0945-1_88.
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Brahim, Meriane, Rahmouni Salah, and Tifouti Issam. "Analysis and Processing of One-Dimensional Signals Using Wavelet." In Recent Advances in Wavelet Transforms and Their Applications. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.104107.
Анотація:
In recent years, wavelet analysis has become an effective and important computational tool in signal processing and image processing applications. Wavelet analysis is known for its successful approach to solving the problem of signal analysis in both the time domain and frequency domain. The analysis of the nonstationary signal generated by physical phenomena has posed a great challenge for various conversion techniques. Transformation techniques such as Fourier transform (FT) and short Fourier transform (STFT) fail to analyze nonstationary signals. But wavelet transform (WT) techniques may be able to efficiently analyze both stable and unstable signals. WT is able to analyze one-dimensional signals, such as audio signals and two-dimensional signals such as images. In this chapter, we discuss wavelet transduction techniques and their applications in detail and focus on the analysis and processing of the wave-encoded laser signal as one-dimensional electrical signals and its use in alarm systems. In the second stage, we filter the speech signal and determine the fundamental frequencies using wavelet transformation.
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Ceccaldi, Jérôme. "Chapitre 49 - Le leadership : quels leviers et quels signaux faibles ?" In Réinventer le leadership, 522. EMS Editions, 2017. http://dx.doi.org/10.3917/ems.frimo.2017.01.0522.
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Kondo, Kazuhiro. "Data Hiding for Stereo Audio Signals." In Advances in Multimedia and Interactive Technologies, 104–28. IGI Global, 2013. http://dx.doi.org/10.4018/978-1-4666-2217-3.ch006.
Анотація:
This chapter proposes two data-hiding algorithms for stereo audio signals. The first algorithm embeds data into a stereo audio signal by adding data-dependent mutual delays to the host stereo audio signal. The second algorithm adds fixed delay echoes with polarities that are data dependent and amplitudes that are adjusted such that the interchannel correlation matches the original signal. The robustness and the quality of the data-embedded audio will be given and compared for both algorithms. Both algorithms were shown to be fairly robust against common distortions, such as added noise, audio coding, and sample rate conversion. The embedded audio quality was shown to be “fair” to “good” for the first algorithm and “good” to “excellent” for the second algorithm, depending on the input source.
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Mu, Xinxin, Hongyu Jiang, Fan Li, Tongjie Pan, Guocheng Xiong, and Yalan Ye. "Physiological Signal-Based Biometric Identification for Discovering and Identifying a New User." In Artificial Intelligence and Human-Computer Interaction. IOS Press, 2024. http://dx.doi.org/10.3233/faia240155.
Анотація:
Using physiological signals acquisition from wearable devices makes biometric identification more convenient and secure. Yet most of existing studies focus on Physiological signal-based biometric technology in a verification application rather than an identification application. Actually, identification application is a more general senior and there is an inevitable problem in discovering and identifying a new user. Existing approaches can only identify trained users and fail to join a new user into model conveniently, which limits identification application in human-computer interaction. In this work, we propose a physiological signal-based method for identifying both older users and new users. A deep network combining Transform and LSTM is introduced to extract user-specific features. Then, one-vs-all classifier is used to identify old users and discover a new user, and the classifier is updated to identify the new user without retraining whole model. Based on electrocardiogram (ECG) and photoplethysmography (PPG) signals in BIDMC dataset, our method achieved an accuracy of 99.52% and 99.30% for old users, as well as 93.18% and 91.23% for a new user. Extensive experiments demonstrate the performance in identifying old users and the effectiveness in discovering and identifying a new user via physiological signals.
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Paterson, Andrew. "Application of the baculoviral expression system to signal transduction." In Signal Transduction, 139–69. Oxford University PressOxford, 1999. http://dx.doi.org/10.1093/oso/9780199637218.003.0007.
Анотація:
Abstract The Baculovirus Expression Vector System (BEYS) is an extremely versatile and powerful laboratory tool (1). In simplest terms, the BEYS allows the forced heterologous expression of recombinant protein in susceptible host strains of insect cells. Gene products from the simplest prokaryotes through to the higher eukaryotes have been expressed successfully in this system. Recombinant proteins are recovered in a folded and active form, and posttranslation modifications, such as phosphorylation, lipid acylation, and simple glycosylation are often preserved. Oligomerization is preserved also, as is the ability to form holomeric complexes. This has been demonstrated clearly with expression of the - 40 k Da G proteins in their native al3 ‘) ‘ heterotrimeric complexes (2), and extended to the activation of the kinase, c-Raf, upon coexpression with Ras and Src tyrosine kinase (3). Since the host insect cells maintain the ability to process eukaryotic pre-mRNA, heterologous expression from genomic DNA is possible. However, the most attractive facet of BEYS must be the high level of heterologous protein expression with values of between 0.1 and 30% of total cell protein being reported, and often with gene products that fail to express with activity or reasonable yield in other systems. The rationale of the BEYS is fairly simple. The baculoviral genome is engineered to incorporate the coding sequence of a foreign protein. Incorporation is directed to a position downstream, and under the control, of a strong viral promoter.
Тези доповідей конференцій з теми "Signaux Faible":
1
Ahmed, Syed Zahid, Yuhui Bai, Imen Dhif, Laurent Lambert, Imen Mhedhbi, Patrick Garda, Bertrand Granado, et al. "SmartEEG: A multimodal tool for EEG signals." In 2014 IEEE Faible Tension Faible Consommation (FTFC). IEEE, 2014. http://dx.doi.org/10.1109/ftfc.2014.6828622.
2
Flandre, Denis, Olivier Bulteel, Geoffroy Gosset, Bertrand Rue, and David Bol. "Disruptive ultra-low-leakage design techniques for ultra-low-power mixed-signal microsystems." In 2011 Faible Tension Faible Consommation (FTFC). IEEE, 2011. http://dx.doi.org/10.1109/ftfc.2011.5948908.
3
Zarkesh-Ha, Payman. "Analysis of low-voltage mixed-signal circuits under device variations." In 2013 IEEE Faible Tension Faible Consommation (FTFC). IEEE, 2013. http://dx.doi.org/10.1109/ftfc.2013.6577756.
4
de Streel, Guerric, Julien De Vos, Denis Flandre, and David Bol. "A 65nm 1V to 0.5V linear regulator with ultra low quiescent current for mixed-signal ULV SoCs." In 2014 IEEE Faible Tension Faible Consommation (FTFC). IEEE, 2014. http://dx.doi.org/10.1109/ftfc.2014.6828597.
5
Dien, Y. "Les signaux faibles à l’aune des lanceurs d’alerte." In Congrès Lambda Mu 19 de Maîtrise des Risques et Sûreté de Fonctionnement, Dijon, 21-23 Octobre 2014. IMdR, 2015. http://dx.doi.org/10.4267/2042/56087.
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Escande, J., C. Proust, and J.-C. Lecoze. "Les signaux faibles : dépasser le problème de l’impossible prédictibilité." In Congrès Lambda Mu 19 de Maîtrise des Risques et Sûreté de Fonctionnement, Dijon, 21-23 Octobre 2014. IMdR, 2015. http://dx.doi.org/10.4267/2042/56089.
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Magne, Jean, Jacques Pignault, and Laurent Dubau. "Signaux "faibles", décisions agiles. S’organiser pour tirer parti de nombreux signaux précurseurs de dangers." In Congrès Lambda Mu 20 de Maîtrise des Risques et de Sûreté de Fonctionnement, 11-13 Octobre 2016, Saint Malo, France. IMdR, 2016. http://dx.doi.org/10.4267/2042/61741.
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Dechy, N., P. Jouniaux, and D. Hadida. "Détection, pertinence et amplification des signaux faibles dans le traitement du retour d’expérience." In Congrès Lambda Mu 19 de Maîtrise des Risques et Sûreté de Fonctionnement, Dijon, 21-23 Octobre 2014. IMdR, 2015. http://dx.doi.org/10.4267/2042/56086.
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Contreras, Victor, and Robert Garnier. "Peut-on améliorer la prévention-gestion qualité client en utilisant les signaux faibles ?" In Congrès Lambda Mu 20 de Maîtrise des Risques et de Sûreté de Fonctionnement, 11-13 Octobre 2016, Saint Malo, France. IMdR, 2016. http://dx.doi.org/10.4267/2042/61742.
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Wang, Fengli, Hua Chen, Aiguo Gu, and Wei Hu. "Data Processing of Pulsation Signals of a Turbine Based on EMD and Teager Energy Operator." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-75023.
Анотація:
Nonstationary and nonlinear signals are often encountered in turbomachinery research and development. Sometimes the frequency of these signals changes with time. One such an example is the pulsating pressure and strain signals measured during engine ramp to find the maximum resonance strain or during engine transient in applications. As the pulsation signals can come from different disturbance sources, detecting the weak useful signals under a noise background can be difficult. For this type of signals, a novel method based on Empirical Mode Decomposition (EMD) and Teager Energy Operator (TEO) is proposed. First, the signals are processed by a self-adaptive Lifting Wavelet Transform (LWT) to remove noises and enhance the Signal to Noise Ratio (SNR). Then the EMD and Correlation Kurtosis (CK) are employed to select the sensitive Intrinsic Mode Functions (IMFs). In the end, TEO algorithm is applied to the selected sensitive IMF to identify the characteristic frequencies. A case of measured sound signal and strain signal from a turbocharger turbine blade was studied to demonstrate the capabilities of the proposed method. In this case the FFT failed to identify the blade vibratory signal at all, and the EEMD method was barely able to do so. The proposed method successfully captured the blade vibration from the both sound and strain signals.
Звіти організацій з теми "Signaux Faible":
1
McGuire, Mark A., Amichai Arieli, Israel Bruckental, and Dale E. Bauman. Increasing Mammary Protein Synthesis through Endocrine and Nutritional Signals. United States Department of Agriculture, January 2001. http://dx.doi.org/10.32747/2001.7574338.bard.
Анотація:
Objectives To determine endocrine factors that regulate the partitioning of amino acids by the mammary gland. To evaluate dietary flow and supply of energy and amino acids and their effects on milk protein synthesis and endocrine status. To use primary cultures of cow mammary epithelial cells to examine the role of specific factors on the rates and pattern of milk protein synthesis. Milk protein is an increasingly valuable component of milk but little is known regarding the specific hormonal and nutritional factors controlling milk protein synthesis. The research conducted for this project has determined that milk protein synthesis has the potential to be enhanced much greater than previously believed. Increases of over 25% in milk protein percent and yield were detected in studies utilizing abomasal infusion of casein and a hyperinsulinemic-euglycemic clamp. Thus, it appears that insulin, either directly or indirectly, can elicit a substantial increase in milk protein synthesis if additional amino acids are supplied. For additional amino acids, casein provided the best response even though substantial decreases in branched chain amino acids occur when the insulin clamp is utilized. Branched chain amino acids alone are incapable of supporting the enhanced milk protein output. The mammary gland can vary both blood flow and extraction efficiency of amino acids to support protein synthesis. A mammary culture system was used to demonstrate specific endocrine effects on milk protein synthesis. Insulin-like growth factor-I when substituted for insulin was able to enhance casein and a-lactalbumin mRNA. This suggests that insulin is a indirect regulator of milk protein synthesis working through the IGF system to control mammary production of casein and a-lactalbumin. Principal component analysis determined that carbohydrate had the greatest effect on milk protein yield with protein supply only having minor effects. Work in cattle determined that the site of digestion of starch did not affect milk composition alone but the degradability of starch and protein in the rumen can interact to alter milk yield. Cows fed diets with a high degree of rumen undegradability failed to specifically enhance milk protein but produced greater milk yield with similar composition. The mammary gland has an amazing ability to produce protein of great value. Research conducted here has demonstrated the unprecedented potential of the metabolic machinery in the mammary gland. Insulin, probably signaling the mammary gland through the IGF system is a key regulator that must be combined with adequate nutrition in order for maximum response.
2
Storm, Servaas. The Art of Paradigm Maintenance: How the ‘Science of Monetary Policy’ tries to deal with the inflation of 2021-2023. Institute for New Economic Thinking Working Paper Series, October 2023. http://dx.doi.org/10.36687/inetwp214.
Анотація:
The macroeconomic models used by major institutions including the Federal Reserve and the International Monetary Fund (IMF) failed to predict the inflation surge during 2021-2023. The output gap, the unemployment gap, the New Keynesian Phillips curve and inflation expectations did not give timely and relevant signals. The re-emergence of inflation thus threw the ‘science of monetary policy’ off the rails. Faced with the choice between changing their paradigm and proving that there is no need to do so, the ‘scientists of monetary policy’ got busy on the proof. As a result, a number of ad-hoc epicycles have been added to the New Keynesian analytical core—with the help of which one can claim to be able to explain the sudden acceleration of inflation post-factum. This paper critically reviews the theoretical and empirical merits of three recent tweaks to the New Keynesian core: using the vacancy ratio as the appropriate measure of real economic activity; hammering on the considerable risk of an imminent wage-price spiral; and the resurrection of the non-linear Phillips curve. The paper concludes by drawing out sobering lessons concerning the art of paradigm maintenance as practiced by the ‘scientists of monetary policy’
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Phillips, Donald, and Yoram Kapulnik. Using Flavonoids to Control in vitro Development of Vesicular Arbuscular Mycorrhizal Fungi. United States Department of Agriculture, January 1995. http://dx.doi.org/10.32747/1995.7613012.bard.
Анотація:
Vesicular-arbuscular mycorrhizal (VAM) fungi and other beneficial rhizosphere microorganisms, such as Rhizobium bacteria, must locate and infect a host plant before either symbiont profits. Although benefits of the VAM association for increased phosphorous uptake have been widely documented, attempts to improve the fungus and to produce agronomically useful amounts of inoculum have failed due to a lack of in vitro production methods. This project was designed to extend our prior observation that the alfalfa flavonoid quercetin promoted spore germination and hyphal growth of VAM fungi in the absence of a host plant. On the Israeli side of the project, a detailed examination of changes in flavonoids and flavonoid-biosynthetic enzymes during the early stages of VAM development in alfalfa found that VAM fungi elicited and then suppressed transcription of a plant gene coding for chalcone isomerase, which normally is associated with pathogenic infections. US workers collaborated in the identification of flavonoid compounds that appeared during VAM development. On the US side, an in vitro system for testing the effects of plant compounds on fungal spore germination and hyphal growth was developed for use, and intensive analyses of natural products released from alfalfa seedlings grown in the presence and absence of microorganisms were conducted. Two betaines, trigonelline and stachydrine, were identified as being released from alfalfa seeds in much higher concentrations than flavonoids, and these compounds functioned as transcriptional signals to another alfalfa microsymbiont, Rhizobium meliloti. However, these betaines had no effect on VAM spore germination or hyphal growth i vitro. Experiments showed that symbiotic bacteria elicited exudation of the isoflavonoids medicarpin and coumestrol from legume roots, but neither compound promoted growth or germination of VAM fungi in vitro. Attempts to look directly in alfalfa rhizosphere soil for microbiologically active plant products measured a gradient of nod-gene-inducing activity in R. meliloti, but no novel compounds were identified for testing in the VAM fungal system in vitro. Israeli field experiments on agricultural applications of VAM were very successful and developed methods for using VAM to overcome stunting in peanuts and garlic grown in Israel. In addition, deleterious effects of soil solarization on growth of onion, carrot and wheat were linked to effects on VAM fungi. A collaborative combination of basic and applied approaches toward enhancing the agronomic benefits of VAM asociations produced new knowledge on symbiotic biology and successful methods for using VAM inocula under field conditions
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Knowles, Donald, and Monica Leszkowicz Mazuz. Transfected Babesia bovis expressing the anti-tick Bm86 antigen as a vaccine to limit tick infestation and protect against virulent challenge. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7598160.bard.
Анотація:
Bovine babesiosis, caused by the apicomplexan parasites Babesiabovisand B. bigemina, is a major tick borne disease of cattle with significant economic importance globally. The vectors of Babesia parasites are R. (Boophilus) annulatusand R. microplus. In Israel these parasites are transmitted manly by R. annulatus. The main goal of the proposal was developing and testing a novel B. bovisvaccine based on stably transfected attenuated B. bovisexpressing the anti-tick Bm86 antigen. This required generating a transfected- attenuated B. bovisparasite containing a bidirectional promoter expressing both, the gfp- bsd selectable marker and the tick vaccine antigen Bm86. The vaccine was tested for its ability to elicit protective immune responses against T. annulatusticks. Efficient control of babesiosis is based on a complex scheme of integrated management, including preventive immunization, anti-babesial chemotherapy and control of tick populations. Live vaccines based on attenuated parasites are the most effective measure to control babesiosis, and are currently used in several countries, including Israel. Live attenuated parasites lead to a chronic infection and development of strong and long term immunity in vaccinated cattle. Still, live vaccines have several limitations, including the difficulty to distinguish among vaccinated and naturally infected cattle and potential for sporadic outbreaks in vaccinated animals. Tick limitation is essential to control babesiosis but the main measure to reduce tick infestation is traditionally approached using acaricides, which is limited by environmental concerns and the development of resistance by the ticks. Alternative tick-control measures including the use of anti-tick vaccines are emerging, and at least partial protective immunity has been achieved against tick vectors by vaccination with recombinant protective tick antigens (ie: Bm86). In addition, the Babesia vaccine development toolbox has been recently expanded with the development of transfection technology in Babesia parasites. In this approved proposal we successfully developed a Babesia live attenuated transfected vaccine, which is able to express a B. bovisMSA-1 signal-Bm86 chimera and eGFP genes under the control of the B. bovisef- 1 and actin promoters respectively. Genetic analysis demonstrated specific stable integration of the transfected genes in the expected ef-1 locus, and immunofluorescence analysis confirmed expression of Bm86 in the surface of transfected parasites. When applied to splenectomized calves, the transfected parasites were able to cause persistent B. bovisinfection with production of antibodies reactive with Bm86 for at least six months. In addition, partial protection against ticks was also observed upon challenging the vaccinated animals with R. annulatuslarvae. However, when used on intact calves, the vaccine failed to elicit detectable immune responses against Bm86, and we are still in the process of interpreting the data and make necessary changes in our experimental approaches. Overall, the results obtained here represent a step forward towards the development of integrated vaccines against both ticks and tick –borne pathogens, using the Babesia attenuated parasites as a platform to the delivery of exogenous protective antigens
5
Blais-Stevens, A., A. Castagner, A. Grenier, and K D Brewer. Preliminary results from a subbottom profiling survey of Seton Lake, British Columbia. Natural Resources Canada/CMSS/Information Management, 2023. http://dx.doi.org/10.4095/332277.
Анотація:
Seton Lake is a freshwater fiord located in southwestern British Columbia, roughly 4 km west of Lillooet and 250 km north-northeast of Vancouver. Located in the Coast Mountains, it is an alpine lake about 22-km long and roughly 1-1.5 km wide. It is separated from nearby Anderson Lake, located to the west, by a large pre-historic rock avalanche deposit at Seton Portage. The lake stands at about 243 m above sea level and is up to about 150 m deep (BC gov., 1953). Water level is controlled by a hydroelectric dam (i.e., Seton dam) located at the eastern end of the lake. Here, the lake drains east into Seton Canal, a 5 km diversion of the flow of the Seton River, which begins at the Seton dam. The Seton Canal pushes water to the Seton Powerhouse, a hydroelectric generating station at the Fraser River, just south of the community of Sekw'el'was and confluence of the Seton River, which drains into the Fraser River at Lillooet. Seton Portage, Shalatlh, South Shalatlh, Tsal'alh (Shalath), Sekw'el'was (Cayoosh Creek), and T'it'q'et (Lillooet) are communities that surround the lake. Surrounded by mountainous terrain, the lake is flanked at mid-slope by glacial and colluvial sediments deposited during the last glacial and deglacial periods (Clague, 1989; Jakob, 2018). The bedrock consists mainly of mafic to ultramafic volcanic rocks with minor carbonate and argillite from the Carboniferous to Middle Jurassic periods (Journeay and Monger, 1994). As part of the Public Safety Geoscience Program at the Geological Survey of Canada (Natural Resources Canada), our goal is to provide baseline geoscience information to nearby communities, stakeholders and decision-makers. Our objective was to see what kind of sediments were deposited and specifically if we could identify underwater landslide deposits. Thus, we surveyed the lake using a Pinger SBP sub bottom profiler made by Knudsen Engineering Ltd., with dual 3.5 / 200 kHz transducers mounted to a small boat (see photo). This instrument transmits sound energy down through the water column that reflects off the lake bottom surface and underlying sediment layers. At the lake surface, the reflected sound energy is received by the profiler, recorded on a laptop computer, and integrated with GPS data. These data are processed to generate a two-dimensional image (or profile) showing the character of the lake bottom and underlying sediments along the route that the boat passed over. Our survey in 2022 recorded 98 profiles along Seton Lake. The red transect lines show the locations of the 20 profiles displayed on the poster. The types of sediments observed are mostly fine-grained glaciolacustrine sediments that are horizontally bedded with a subtle transition between glaciolacustrine to lacustrine (e.g., profiles A-A'; C-C'; F-F'; S-S'). Profile S-S' displays this transition zone. The glaciolacustrine sediments probably were deposited as the Cordilleran Ice Sheet retreated from the local area (~13,000-11,000 years ago; Clague, 2017) and the lacustrine sediments, after the ice receded to present-day conditions. Some of the parallel reflections are interrupted, suggesting abrupt sedimentation by deposits that are not horizontally bedded; these are interpreted as landslide deposits (see pink or blue deposits on profiles). The deposits that show disturbance in the sedimentation found within the horizontal beds are thought to be older landslides (e.g., blue arrows/deposits in profiles C-C'; E-E'; F-F'; G-G'; I-I'; J-J'; K-K'; N-N'; P-P'; Q-Q'; R-R'; T-T'; U-U'), but the ones that are found on top of the horizontally laminated sediments (red arrows/pink deposits), and close to the lake wall, are interpreted to be younger (e.g., profiles B-B'; C-C'; H-H'; K-K'; M-M'; O-O'; P-P'; Q-Q'). At the fan delta just west of Seton dam, where there was no acoustic signal penetration, it is interpreted that the delta failed and brought down coarser deposits at the bottom of the lake (e.g., profiles H-H'; M-M'; and perhaps K-K'). However, these could be glacial deposits, bedrock, or other coarser deposits. Some of the deposits that reflect poor penetration of the acoustic signal, below the glaciolacustrine sediments, could represent glacial deposits, old landslide deposits, or perhaps the presence of gas (orange arrows; e.g, B-B'; D-D'; J-J'; O-O', T-T'). The preliminary results from sub bottom profiling reveal that there are underwater landslides deposits of widely varying ages buried in the bottom of the lake. However, the exact timing of these is not known. Hence our preliminary survey gives an overview of the distribution of landslides where there seems to be a larger number of landslides recorded in the narrower eastern portion of the lake.
6
Gunay, Selim, Fan Hu, Khalid Mosalam, Arpit Nema, Jose Restrepo, Adam Zsarnoczay, and Jack Baker. Blind Prediction of Shaking Table Tests of a New Bridge Bent Design. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, November 2020. http://dx.doi.org/10.55461/svks9397.
Анотація:
Considering the importance of the transportation network and bridge structures, the associated seismic design philosophy is shifting from the basic collapse prevention objective to maintaining functionality on the community scale in the aftermath of moderate to strong earthquakes (i.e., resiliency). In addition to performance, the associated construction philosophy is also being modernized, with the utilization of accelerated bridge construction (ABC) techniques to reduce impacts of construction work on traffic, society, economy, and on-site safety during construction. Recent years have seen several developments towards the design of low-damage bridges and ABC. According to the results of conducted tests, these systems have significant potential to achieve the intended community resiliency objectives. Taking advantage of such potential in the standard design and analysis processes requires proper modeling that adequately characterizes the behavior and response of these bridge systems. To evaluate the current practices and abilities of the structural engineering community to model this type of resiliency-oriented bridges, the Pacific Earthquake Engineering Research Center (PEER) organized a blind prediction contest of a two-column bridge bent consisting of columns with enhanced response characteristics achieved by a well-balanced contribution of self-centering, rocking, and energy dissipation. The parameters of this blind prediction competition are described in this report, and the predictions submitted by different teams are analyzed. In general, forces are predicted better than displacements. The post-tension bar forces and residual displacements are predicted with the best and least accuracy, respectively. Some of the predicted quantities are observed to have coefficient of variation (COV) values larger than 50%; however, in general, the scatter in the predictions amongst different teams is not significantly large. Applied ground motions (GM) in shaking table tests consisted of a series of naturally recorded earthquake acceleration signals, where GM1 is found to be the largest contributor to the displacement error for most of the teams, and GM7 is the largest contributor to the force (hence, the acceleration) error. The large contribution of GM1 to the displacement error is due to the elastic response in GM1 and the errors stemming from the incorrect estimation of the period and damping ratio. The contribution of GM7 to the force error is due to the errors in the estimation of the base-shear capacity. Several teams were able to predict forces and accelerations with only moderate bias. Displacements, however, were systematically underestimated by almost every team. This suggests that there is a general problem either in the assumptions made or the models used to simulate the response of this type of bridge bent with enhanced response characteristics. Predictions of the best-performing teams were consistently and substantially better than average in all response quantities. The engineering community would benefit from learning details of the approach of the best teams and the factors that caused the models of other teams to fail to produce similarly good results. Blind prediction contests provide: (1) very useful information regarding areas where current numerical models might be improved; and (2) quantitative data regarding the uncertainty of analytical models for use in performance-based earthquake engineering evaluations. Such blind prediction contests should be encouraged for other experimental research activities and are planned to be conducted annually by PEER.
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Fluhr, Robert, and Maor Bar-Peled. Novel Lectin Controls Wound-responses in Arabidopsis. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7697123.bard.
Анотація:
Innate immune responses in animals and plants involve receptors that recognize microbe-associated molecules. In plants, one set of this defense system is characterized by large families of TIR–nucleotide binding site–leucine-rich repeat (TIR-NBS-LRR) resistance genes. The direct interaction between plant proteins harboring the TIR domain with proteins that transmit and facilitate a signaling pathway has yet to be shown. The Arabidopsis genome encodes TIR-domain containing genes that lack NBS and LRR whose functions are unknown. Here we investigated the functional role of such protein, TLW1 (TIR LECTIN WOUNDRESPONSIVE1). The TLW1 gene encodes a protein with two domains: a TIR domain linked to a lectin-containing domain. Our specific aim in this proposal was to examine the ramifications of the TL1-glycan interaction by; A) The functional characterization of TL1 activity in the context of plant wound response and B) Examine the hypothesis that wounding induced specific polysaccharides and examine them as candidates for TL-1 interactive glycan compounds. The Weizmann group showed TLW1 transcripts are rapidly induced by wounding in a JA-independent pathway and T-DNA-tagged tlw1 mutants that lack TLW1 transcripts, fail to initiate the full systemic wound response. Transcriptome methodology analysis was set up and transcriptome analyses indicates a two-fold reduced level of JA-responsive but not JA-independent transcripts. The TIR domain of TLW1 was found to interact directly with the KAT2/PED1 gene product responsible for the final b-oxidation steps in peroxisomal-basedJA biosynthesis. To identify potential binding target(s) of TL1 in plant wound response, the CCRC group first expressed recombinant TL1 in bacterial cells and optimized conditions for the protein expression. TL1 was most highly expressed in ArcticExpress cell line. Different types of extraction buffers and extraction methods were used to prepare plant extracts for TL1 binding assay. Optimized condition for glycan labeling was determined, and 2-aminobenzamide was used to label plant extracts. Sensitivity of MALDI and LC-MS using standard glycans. THAP (2,4,6- Trihydroxyacetophenone) showed minimal background peaks at positive mode of MALDI, however, it was insensitive with a minimum detection level of 100 ng. Using LC-MS, sensitivity was highly increased enough to detect 30 pmol concentration. However, patterns of total glycans displayed no significant difference between different extraction conditions when samples were separated with Dionex ICS-2000 ion chromatography system. Transgenic plants over-expressing lectin domains were generated to obtain active lectin domain in plant cells. Insertion of the overexpression construct into the plant genome was confirmed by antibiotic selection and genomic DNA PCR. However, RT-PCR analysis was not able to detect increased level of the transcripts. Binding ability of azelaic acid to recombinant TL1. Azelaic acid was detected in GST-TL1 elution fraction, however, DHB matrix has the same mass in background signals, which needs to be further tested on other matrices. The major findings showed the importance of TLW1 in regulating wound response. The findings demonstrate completely novel and unexpected TIR domain interactions and reveal a control nexus and mechanism that contributes to the propagation of wound responses in Arabidopsis. The implications are to our understanding of the function of TIR domains and to the notion that early molecular events occur systemically within minutes of a plant sustaining a wound. A WEB site (http://genome.weizmann.ac.il/hormonometer/) was set up that enables scientists to interact with a collated plant hormone database.
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Miller, Gad, and Jeffrey F. Harper. Pollen fertility and the role of ROS and Ca signaling in heat stress tolerance. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7598150.bard.
Анотація:
The long-term goal of this research is to understand how pollen cope with stress, and identify genes that can be manipulated in crop plants to improve reproductive success during heat stress. The specific aims were to: 1) Compare heat stress dependent changes in gene expression between wild type pollen, and mutants in which pollen are heat sensitive (cngc16) or heat tolerant (apx2-1). 2) Compare cngc16 and apx2 mutants for differences in heat-stress triggered changes in ROS, cNMP, and Ca²⁺ transients. 3) Expand a mutant screen for pollen with increased or decreased thermo-tolerance. These aims were designed to provide novel and fundamental advances to our understanding of stress tolerance in pollen reproductive development, and enable research aimed at improving crop plants to be more productive under conditions of heat stress. Background: Each year crop yields are severely impacted by a variety of stress conditions, including heat, cold, drought, hypoxia, and salt. Reproductive development in flowering plants is highly sensitive to hot or cold temperatures, with even a single hot day or cold night sometimes being fatal to reproductive success. In many plants, pollen tube development and fertilization is often the weakest link. Current speculation about global climate change is that most agricultural regions will experience more extreme environmental fluctuations. With the human food supply largely dependent on seeds, it is critical that we consider ways to improve stress tolerance during fertilization. The heat stress response (HSR) has been intensively studied in vegetative tissues, but is poorly understood during reproductive development. A general paradigm is that HS is accompanied by increased production of reactive oxygen species (ROS) and induction of ROS-scavenging enzymes to protect cells from excess oxidative damage. The activation of the HSR has been linked to cytosolic Ca²⁺ signals, and transcriptional and translational responses, including the increased expression of heat shock proteins (HSPs) and antioxidative pathways. The focus of the proposed research was on two mutations, which have been discovered in a collaboration between the Harper and Miller labs, that either increase or decrease reproductive stress tolerance in a model plant, Arabidopsis thaliana (i.e., cngc16--cyclic nucleotide gated channel 16, apx2-1--ascorbate peroxidase 2,). Major conclusions, solutions, achievements. Using RNA-seq technology, the expression profiles of cngc16 and apx2 pollen grains were independently compared to wild type under favourable conditions and following HS. In comparison to a wild type HSR, there were 2,776 differences in the transcriptome response in cngc16 pollen, consistent with a model in which this heat-sensitive mutant fails to enact or maintain a normal wild-type HSR. In a comparison with apx2 pollen, there were 900 differences in the HSR. Some portion of these 900 differences might contribute to an improved HSR in apx2 pollen. Twenty-seven and 42 transcription factor changes, in cngc16 and apx2-1, respectively, were identified that could provide unique contributions to a pollen HSR. While we found that the functional HS-dependent reprogramming of the pollen transcriptome requires specific activity of CNGC16, we identified in apx2 specific activation of flavonol-biosynthesis pathway and auxin signalling that support a role in pollen thermotolerance. Results from this study have identified metabolic pathways and candidate genes of potential use in improving HS tolerance in pollen. Additionally, we developed new FACS-based methodology that can quantify the stress response for individual pollen in a high-throughput fashion. This technology is being adapted for biological screening of crop plant’s pollen to identify novel thermotolerance traits. Implications, both scientific and agricultural. This study has provided a reference data on the pollen HSR from a model plant, and supports a model that the HSR in pollen has many differences compared to vegetative cells. This provides an important foundation for understanding and improving the pollen HSR, and therefor contributes to the long-term goal of improving productivity in crop plants subjected to temperature stress conditions. A specific hypothesis that has emerged from this study is that pollen thermotolerance can be improved by increasing flavonol accumulation before or during a stress response. Efforts to test this hypothesis have been initiated, and if successful have the potential for application with major seed crops such as maize and rice.