Academic literature on the topic 'Spectre de distance'
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Journal articles on the topic "Spectre de distance"
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Mbekhta, Mostafa. "Formules de distance au spectre généralisé et au spectre semi-Fredholm." Journal of Functional Analysis 194, no. 2 (October 2002): 231–47. http://dx.doi.org/10.1006/jfan.2002.3969.
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Watts, Stéphanie, André Marchand, Stéphane Bouchard, and Mélyane Bombardier. "L’alliance thérapeutique lors d’une télépsychothérapie PAR VIDÉOCONFÉRENCE pour un trouble DU SPECTRE anxieux : Recension systématique deS ÉCRITS." ARTICLES LIBRES 37, no. 3 (June 14, 2017): 277–302. http://dx.doi.org/10.7202/1040171ar.
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La présente recension des écrits a pour objectif d’évaluer s’il est possible de développer une alliance thérapeutique (AT) de qualité au cours d’une intervention psychologique individuelle administrée par vidéoconférence pour un trouble du spectre anxieux. Dix études sont recensées. Les résultats indiquent qu’une AT de qualité peut se construire lors d’une télépsychothérapie pour un trouble du spectre anxieux. Toutefois, davantage d’études se doivent d’être menées afin d’apporter un appui empirique supplémentaire à la question. Une meilleure compréhension des conditions pouvant favoriser l’établissement d’une relation thérapeutique à distance se doit également d’être visée afin d’orienter les professionnels de la santé vers une utilisation judicieuse de cette modalité d’intervention novatrice.
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Ferland1, Catherine. "Le nectar et l’ambroisie." Revue d'histoire de l'Amérique française 58, no. 4 (March 6, 2006): 475–505. http://dx.doi.org/10.7202/012210ar.
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Résumé À l’époque moderne, consommer du vin et des liqueurs constitue un marqueur identitaire pour l’élite, au même titre que le bas de soie ou la perruque. Au xviiie siècle, les membres de l’élite de la Nouvelle-France boivent en se conformant aux normes en vigueur chez leur homologue métropolitaine, depuis le choix et le service des boissons jusqu’à leur absorption et, parfois, de l’ivresse qu’elles procurent. On prend également soin de respecter les prescriptions sociales liées au Boire, particulièrement celles relatives au genre. Cette façon d’afficher des manières de boire bien françaises sert à marquer la distance qui les sépare des gens du peuple et ainsi de s’éloigner du spectre de la « sauvagerie », mais sert aussi à affirmer leur filiation identitaire avec la France, en perpétuant leur appartenance à la culture française et, par extension, à la « civilisation ».
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Cantelli, Fabrizio. "Deux conceptions de l’empowerment." Articles 32, no. 1 (September 26, 2013): 63–87. http://dx.doi.org/10.7202/1018721ar.
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La catégorie d’empowermentdevient omniprésente quand il s’agit de participation. Pourtant, peu de travaux en ont exploré sociologiquement les contours, les propriétés et la portée. Il s’agit de prendre distance avec une approche unidimensionnelle de la catégorie, qui l’appréhende comme une solution démocratique ou une régression liée à un usage managérial. Notre démarche comparative élargie considère plusieurs espaces-temps, ce qui permet de rendre compte de deux manières très différentes de penser le pouvoir et d’agir sur des capacités. Cet article interroge deux conceptions de l’empowerment, soit deux philosophies du pouvoir sous-jacentes : une gestionnaire et une civique. Pour saisir les conceptions gestionnaires de l’empowerment, notre article s’appuie sur un spectre allant du cas spécifique de la Banque mondiale (Empowerment Team) à plusieurs acteurs de la santé en relation avec les institutions européennes. Concernant les conceptions civiques de l’empowerment, l’enquête repose sur le mouvement des droits civiques aux États-Unis et leBlackpowerdans les années 1960, tout en s’interrogeant sur l’héritage contemporain.
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Yvon, Florence, and Antoinette Prouteau. "Vers une compréhension de la stigmatisation : quel est le stéréotype associé à la schizophrénie ?" Santé mentale au Québec 42, no. 2 (November 16, 2017): 125–31. http://dx.doi.org/10.7202/1041919ar.
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La stigmatisation des personnes souffrant d’un trouble du spectre schizophrénique a pour origine l’existence d’un stéréotype associé à une catégorie sociale, ici la schizophrénie. L’objectif de cet article bref est de proposer une courte synthèse de la littérature récente ayant exploré le contenu du stéréotype associé à la schizophrénie, en anglais et en français, et de proposer des perspectives de recherche basées sur les évolutions récentes de ce domaine. Le stéréotype associé à la maladie mentale en général est clairement négatif. Le modèle le plus répandu dans la littérature postule l’existence de quatre facteurs qui en constituent le contenu : attribution de la responsabilité de la maladie, dangerosité, faible pronostic, imprévisibilité et incompétence dans les rôles sociaux. Si le stéréotype peut varier selon les pays, il est clairement associé à la discrimination et au désir de mettre les personnes à distance socialement. Le stéréotype diffère également entre les maladies mentales. En comparaison aux troubles bipolaires ou à l’autisme, la schizophrénie concentre les aspects les plus négatifs du stéréotype associé à la maladie mentale, notamment en termes de dangerosité et de distance sociale. L’étude du stéréotype, en pleine expansion, demande encore des études spécifiques et la mise à l’épreuve des modèles non validés, pourtant largement utilisés dans la littérature psychiatrique. L’importation des méthodes et des modèles de la psychologie sociale constitue une piste prometteuse. Ainsi, la production de données utilisables par tous les acteurs du terrain, usagers, familles et professionnels, implique la constitution d’équipes pluridisciplinaires dans les projets futurs.
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Collins, Sarah. "Practices of Aesthetic Self-Cultivation: British Composer-Critics of the ‘Doomed Generation’." Journal of the Royal Musical Association 138, no. 1 (2013): 85–128. http://dx.doi.org/10.1080/02690403.2013.771975.
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AbstractThe spectre of music as a transcendent artistic ideal figures prominently in the literary criticism of Victorian aestheticism, though the extent to which aestheticism of the movement actually influenced the thinking of British composers has received only marginal scholarly attention. By the first decades of the twentieth century, aestheticism had become decidedly unfashionable even in literary circles, so it is unsurprising that composers of the time would choose to distance themselves from its rhetoric. The prevalence of a certain type of metaphysical conception of the creative act of the artist and intuitive act of the critic, however, may suggest an important remnant of aesthetic influence. Drawing from new critical trends which themselves mirror those of aestheticism, this article posits a revised conception of aesthetic discourse as an activity of self-cultivation, and examines its role in shaping the lives of selected British composer-critics from the early part of the twentieth century. By casting the aesthetic ethos not as a doctrine but as a set of internal practices that inform the creation and subversion of doctrine, the article demonstrates how a ‘relational musicology’ can act as a tool for historical inquiry.
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Notarangelo, Cristina. "On how the universality of rights translates into national politics and practices of exclusion: The spectre of precarity among young “migrants”." Anuac 2, no. 2 (June 28, 2015): 26–42. http://dx.doi.org/10.7340/anuac2239-625x-100.
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The structural presence of young migrants leads us to investigate the different levels and practices through which inclusion and exclusion processes are declined in daily life also considering the persistence of apparent and concealed barriers affecting the construction of new forms of political, social and cultural cohesion. Drawing on life stories of young people who arrived in Italy from the country of origin at different stages of their educational formation and socialization process and on fieldwork, this ethnographic paper explores the material and symbolic consequences engendered by the tension existing between Italian educational policy and norms regulating the status of migrants and more in general the effects of immigration policies. A case study conducted in the city of Genoa provides evidence of discrepancies between the aims of some institutions, in particular schools, which even if with lots of contradictions try to valorize multiple belongings and to adhere to international Conventions on human rights, and an “outside” context which ties the permit of residence in Italy to the sphere of labour or to the involvement in the education system provided that the family of a dependent major student have the required income. This fact limits the opportunities and redefines the rights both of second generations and adult migrants educated elsewhere and migrated in search for a new or better life. The expectations of young migrants with multiple identities are thus betrayed because they have to confront walls and barriers which distance them from citizens, citizenship and connected rights.
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Campion, D. "Génétique épidémiologique de la schizophrénie. Données récentes et stratégies de recherche." Psychiatry and Psychobiology 4, no. 3 (1989): 139–50. http://dx.doi.org/10.1017/s0767399x00001565.
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RésuméLes études épidemiologiques ont mis en évidence une agrégation familiale de la schizophrénie et ont permis de préciser l’étendue du spectre (cf. Tableaux I et II).Cependant, ces résultats n’impliquent pas automatiquement l’existence d’une composante génétique dans le déterminisme de la maladie. Pour établir la présence de cette composante, on utilise les analyses de ségrégation, de linkage et d’association. Les études de ségrégation, bien qu’elles souffrent de nombreuses limitations, sont plutôt en faveur d’une transmission polygénique avec effet de seuil. Les études de linkage utilisant la méthode des Lod Scores sont encore rares et, comme dans toutes les maladies oú le mode de transmission n’est pas connu, leur emploi pose des problémes méthodologiques complexes. Il semble toutefois que si la détermination de la distance entre le géne pathologique et le marqueur utilisé est sensible á des erreurs sur les paramétres caractérisant le locus de susceptibilité, on ne puisse conclure á un faux linkage á partir de données erronées. Pour effectuer un test de linkage, on peut également employer la méthode des germains malades (Affected Sib Pair), qui, bien que moins puissante, offre des avantages lorsque le mode de transmission de la maladie est mal connu. Enfin, l’interêt d’une étude d’association en utilisant des polymorphismes de restriction au voisinage de génes candidats est souligné. De toute évidence, ces différentes approches devront être combinées dans la recherche des facteurs génétiques prédisposant á la schizophrénie.
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Graovac, Ante, Gani Jashari, and Mate Strunje. "On the distance spectrum of a cycle." Applications of Mathematics 30, no. 4 (1985): 286–90. http://dx.doi.org/10.21136/am.1985.104151.
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Zhang, Zhiyong, Shuo Wang, and Yanqing Zhang. "Non-Destructive Detection of Water Content in Pork Based on NIR Spatially Resolved Spectroscopy." Agriculture 13, no. 11 (November 8, 2023): 2114. http://dx.doi.org/10.3390/agriculture13112114.
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Water is one of the important factors affecting pork quality. In this study, near-infrared (NIR) spatially resolved (SR) spectroscopy was used to detect the water content of pork. The SR spectra of 150 pork samples were collected within the light source–detector (LS-D) distance range of 4–20 mm (distance interval 1 mm). Models were established based on single-point SR spectra of 17 different LS-D distances and combination SR spectra. The results indicated that combination SR spectra achieved better model performance than the single-point SR spectra, and the LS-D distance significantly affected the model accuracy. The optimal LS-D distance combination of 5, 7, 10, and 12 mm provided the best detection model with the calibration determination coefficient (R2C) of 0.915 and prediction determination coefficient (R2P) of 0.878. Using the competitive adaptive reweighted sampling (CARS) algorithm, 24 characteristic wavelengths were selected. The model built with the characteristic wavelengths also exhibited good detection accuracy, with a R2C of 0.909 and a R2P of 0.867, and the number of wavelengths was greatly reduced compared to the full-wavelength model. This study demonstrated that SR spectroscopy combined with the optimized LS-D distances and screened characteristic wavelengths can be a powerful tool for detecting the water content of pork.
Dissertations / Theses on the topic "Spectre de distance"
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Ellouze, Malek. "Propriétés de distance des codes polaires : théorie et applications." Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0132.
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Les codes correcteurs d'erreurs sont essentiels pour garantir des transmissions de données fiables, surtout dans des contextes où diverses interférences peuvent compromettre l'intégrité des informations.Les codes polaires sont l'une des familles de codes correcteurs d'erreurs les plus compétitives. Ils peuvent atteindre la capacité du canal de Shannon grâce à un encodage et un décodage efficaces pour de très grandes tailles de codes. Pour ces raisons, les codes polaires ont été inclus dans le standard 5G. De plus, ils sont l'objet de plusieurs recherches pour le futur standard 6G.Cependant, les codes polaires tels que initialement construits pour un décodage à annulations successives (SC) atteignent des performances limitées pour une taille modérée de codes. Cela est lié d’une part à leurs faibles propriétés de distance et d'autre part à la nature du décodage à décision dure. Cependant grâce à l'utilisation d'un décodage par listes principalement ainsi que plusieurs autres améliorations, notamment la pré-transformation, les codes polaires sont désormais compétitifs par rapport aux codes LDPC et aux turbo-codes.Dans ce contexte, cette thèse a pour objet l'étude et l’analyse des codes polaires en se concentrant sur deux aspects fondamentaux qui influencent ces performances : leurs propriétés de distance et leurs performances pour un décodage par listes.Après une revue approfondie de la définition des codes polaires, des différentes variantes, des algorithmes de décodage et des concepts liés à leur spectre de distances, une première contribution est permet de caractériser une partie des propriétés de distance des codes polaires classiques et pré-transformés. Cette méthode présente l'avantage d'être totalement indépendante de la construction code. C'est pourquoi, elle peut être appliquée à différentes configurations. De plus, l'approche proposée se distingue par une complexité de calcul moins élevée que les méthodes présentes dans la littérature.Les techniques de poinçonnage et de raccourcissement des codes polaires sont introduites comme des variantes permettant d’obtenir des codes polaires dont les tailles ne sont pas nécessairement des puissance de deux. Une deuxième contribution consiste à généraliser l’approche développée dans le cadre de la thèse aux codes polaires poinçonnés et raccourcis. Il est à souligner que cette dernière peut être appliquée quelque soit la technique de poinçonnage et/ou de raccourcissement..Finalement, la question de la taille de liste nécessaire pour un décodage liste (SCL) afin d’atteindre les performances de maximum de vraisemblance est traitée. Celle-ci étant dépendante de la construction du code, un algorithme est proposé afin d’estimer la taille moyenne de liste nécessaire pour atteindre les meilleurs performances de décodage. Cela constitue une contribution très utile pour la construction de codes qui offrent un compromis entre les propriétés de distance et un décodage par liste ayant une complexité calculatoire maîtriséeError-correcting codes are essential for ensuring reliable data transmission, especially in contexts where various interferences may compromise data integrity. Polar codes are one of the most competitive families of error-correcting codes. They can achieve Shannon channel capacity through efficient encoding and decoding for very large code lengths. For these reasons, polar codes have been included in the 5G standard. Additionally, they are the subject of several research efforts for the future 6G standard.However, polar codes, as originally designed for successive cancellation (SC) decoding, exhibit limited performance for moderate code lengths. This is in part due to their weak distance properties and partly to the nature of hard decision decoding. However, with the use of mainly list decoding and several other enhancements, including pre-transformation, polar codes are now competitive with LDPC and turbo codes.In this context, this thesis aims to study and analyze polar codes focusing on two fundamental aspects that influence their performance: their distance properties and their performance for list decoding.After a comprehensive review of polar code definition, various variants, decoding algorithms, and concepts related to their distance spectrum, a first contribution characterizes some distance properties of classical and pre-transformed polar codes. This method has the advantage of being entirely independent of code construction, making it applicable to different configurations. Moreover, the proposed approach distinguishes itself by having lower computational complexity than methods in the existing literature.Polar code puncturing and shortening techniques are introduced as variants to obtain polar codes whose sizes are not necessarily powers of two. A second contribution involves generalizing the developed approach within the thesis to punctured and shortened polar codes. It is noteworthy that this approach can be applied regardless of the puncturing and/or shortening technique used.Finally, the question of the list size necessary for list decoding (SCL) to achieve maximum likelihood performance is addressed. Since this depends on code construction, an algorithm is proposed to estimate the average list size required to achieve the best decoding performance. This constitutes a very useful contribution for constructing codes that offer a compromise between distance properties and list decoding with controlled computational complexity
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Amaral, Souto Sérgio Paulo. "Ordre à moyenne distance dans les verres de borate ternaires." Paris 6, 1994. http://www.theses.fr/1994PA066300.
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Par spectroscopie Raman a basse fréquence, l'ordre a moyenne distance a été mis en évidence dans les verres de borate ternaires (halogenoborate ou sulfoborate de lithium). Les propriétés acoustiques et le spectre Raman ont été mesurés en fonction de la concentration et de la nature du sel dopant pour deux familles d'échantillons avec un rapport o/b=1,6 et 1,8. Les densités d'état de vibration ont été déduites en supposant que le coefficient de couplage pour l'intensité Raman est proportionnel à la fréquence. Les densités d'état de vibration présentent un excès, dans la région de basse fréquence, par rapport le verre de borate binaire de même rapport o/b. Ces résultats s'interprètent en considérant que l'introduction d'un sel dopant produit des structures ordonnées à moyenne distance, formées par un, deux ou trois cycles diborates selon la nature du sel sauf dans le cas des fluorborate ou des sulfoborate ou un mécanisme dans lequel l'anion contribue à la matrice vitreuse est proposé.
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Bertrand, Jérôme. "Pincement spectral en courbure positive." Paris 11, 2003. https://tel.archives-ouvertes.fr/tel-00008705.
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Sur l'ensemble des variétés Riemanniennes compactes à courbure de Ricci positive (on normalise par Ric ≥ (n -1)g), la première valeur propre du Laplacien agissant sur les fonctions atteint son minimum uniquement pour la sphère canonique. Dans cette thèse, nous caractérisons, à l'aide de la distance de Gromov-Hausdorff, les variétés Riemanniennes à courbure positive dont les premières valeurs propres du Laplacien sont proches de celles de la sphère canonique. Cette propriété de minimimalité du spectre de la sphère s'étend par un procédé de symétrisation, au spectre de Dirichlet des boules géodésiques de la sphère parmi les domaines de variétés à courbure de Ricci positive. Nous étudions les domaines de variétés à courbure de Ricci positive dont la première valeur propre de Dirichlet est presque minimale. En particulier, nous montrons qu'un domaine dont la première valeur propre de Dirichlet est proche de celle d'un hémisphère est Gromov-Hausdorff proche d'un hémisphère d'un sinus produit torduOn the set of compact Riemannian manifolds with positive Ricci curvature (normalized by Ric ≥ (n-1)g), the first eigenvalue of the Laplacian acting on functions reaches its minimum only for the round sphere. In this thesis, we characterize, using the Gromov-Hausdorff distance, Riemannian manifolds with positive Ricci curvature whose first eigenvalues are close to those of the round sphere. This property of minimality of the spectrum of the round sphere has been extended by a symmetrization principle, to the Dirichlet spectrum of the geodesic balls of the round sphere among the domains of Riemannian manifolds with positive curvature. We study the domains of Riemannian manifolds with positive Ricci curvature whose first Dirichlet eigenvalue is almost minimal. In particular, we show that a domain whose first Dirichlet eigenvalue is close to the one of a hemisphere is Gromov-Hausdorff close to a hemisphere of a sine warped product
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Cerocchi, Filippo. "Dynamical and Spectral applications of Gromov-Hausdorff Theory." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENM077/document.
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Cette thèse est divisée en deux parties. La première est consacrée à la méthode du barycentre, introduite en 1995 par G. Besson, G. Courtois et S. Gallot pour résoudre la conjecture de l'Entropie Minimale. Dans le Chapitre 1 nous décrivons ses développements les plus récents, notamment l'extension de cette méthode au cadre des variétés dont la courbure sectionnelle est de signe quelconque (voir les énoncés 1.2.1 et 1.4.1). Dans le Chapitre 2 et 3 nous présentons des résultats dans lesquels la méthode du barycentre joue un rôle important. Le problème “deux variétés dont les flots géodésiques sont conjugués sont-elles isométriques ?” (problème de la rigidité par conjugaison des flots) est le thème du Chapitre 2. Après avoir montré que deux telles variétés ont la même géométrie à grande échelle, on montre comment on peut utiliser ce résultat et la méthode du barycentre pour donner une nouvelle preuve de la rigidité (par conjugaison des flots) des variétés plates. Dans le Chapitre 3 nous utilisons la méthode du barycentre (en courbure de signe quelconque) et des inégalités de Sobolev itérées pour démontrer un théorème de comparaison entre les spectres de deux variétés riemanniennes (Y , g) et (X , g') de volumes proches, sachant qu'il existe une approximation de Gromov-Hausdorff de degré non nul entre ces deux variétés. Il s'agit d'un résultat d'approximation avec majoration de l'erreur d'approximation (et pas seulement d'un résultat de convergence). Remarquons qu'il n'est fait aucune autre hypothèse géométrique (et en particulier aucune hypothèse de courbure) sur la variété (Y , g), ce qui autorise un grand nombre de contre-exemples prouvant que le résultat est optimal. Dans la deuxième partie de la thèse (chapitre 4), on démontre un Lemme de Margulis sans hypothèse sur la courbure, qui s'applique aux variétés dont les groupes fondamentaux sont des produits libres (et qui ne possèdent pas d'élément de torsion d'ordre 2). Nous donnons également une borne inférieure de la systole des variétés dont le diamètre et l'entropie volumique sont majorés et dont le groupe fondamental est isomorphe à un produit libre sans torsion. Comme conséquences de ce dernier résultat nous obtenons des résultats de précompacité et de finitude topologique ou différentiable pour les variétés riemanniennes et une minoration de leur volume, tout ceci sans faire d'hypothèse de courbureThis Ph.D. Thesis is divided into two parts. In the first part we present the barycenter method, a technique which has been introduced by G. Besson, G. Courtois and S. Gallot in 1995, in order to solve the Minimal Entropy conjecture. In Chapter 1 we are interested in the more recent developments of this method, more precisely in the recent extension of the method to the case of manifolds having sectional curvature of variable sign. In Chapters 2 and 3 we shall present some new results whose proofs make use of the barycenter method. The Conjugacy Rigidity problem is the theme of Chapter 2. First we show a general result which provide a comparison between the large scale geometry of the Riemannian universal coverings of two compact manifolds whose geodesic flows are conjugates. Then we shall show how we can apply the latter result and the barycenter method in curvature of variable sign in order to give a new proof of the conjugacy rigidity of flat manifolds. In Chapter 3 we shall give a proof of a spectra comparison theorem for a compact Riemannian manifold which admits a Gromov-Hausdorff-approximation of non zero absolute degree on a fixed compact manifold (X,g') and which has volume almost smaller than the one of the reference manifold. The proof relies on the barycenter method in curvature of variable sign and on iterated Sobolev inequalities. We underline that it is an approximation result (and not just a convergence result) and that no curvature assumptions are made or inferred on (Y,g). The second part of the Thesis consists of a single chapter. In this chapter we prove a Margulis Lemma without curvature assumptions for Riemannian manifolds having decomposable 2-torsionless fundamental group. We shall give also a proof of a universal lower bound for the homotopy systole of compact Riemannian manifolds having bounded volume entropy and diameter, and decomposable torsionless fundamental group. As a consequence of the latter result we shall deduce a Precompactness and Finiteness theorem and a Volume estimate without curvature assumptions
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Stolle, Martin Tobias. "Vers le vol à voile longue distance pour drones autonomes." Thesis, Toulouse, ISAE, 2017. http://www.theses.fr/2017ESAE0006.
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Les petit drones à voilure fixe rendent services aux secteurs de la recherche, de l'armée et de l'industrie, mais souffrent toujours de portée et de charge utile limitées. Le vol thermique permet de réduire la consommation d'énergie. Cependant,sans télédétection d'ascendances, un drone ne peut bénéficier d'une ascendance qu'en la rencontrant par hasard. Dans cette thèse, un nouveau cadre pour le vol à voile longue distance autonome est élaboré, permettant à un drone planeur de localiser visuellement des ascendances sous-cumulus et d’en récolter l'énergie de manière efficace. S'appuyant sur le filtre de Kalman non parfumé, une méthode de vision monoculaire est établie pour l'estimation des paramètres d’ascendances. Sa capacité de fournir des estimations convergentes et cohérentes est évaluée par des simulations Monte Carlo. Les incertitudes de modèle, le bruit de traitement de l'image et les trajectoires de l'observateur peuvent dégrader ces estimés. Par conséquent, un deuxième axe de cette thèse est la conception d'un planificateur de trajectoire robuste basé sur des cartes d'ascendances. Le planificateur fait le compromis entre le temps de vol et le risque d’un atterrissage forcé dans les champs tout en tenant compte des incertitudes d'estimation dans le processus de prise de décision. Il est illustré que la charge de calcul du planificateur de trajectoire proposé est réalisable sur une plate-forme informatique peu coûteuse. Les algorithmes proposés d’estimation ainsi que de planification sont évalués conjointement dans un simulateur de vol à 6 axes, mettant en évidence des améliorations significatives par rapport aux vols à voile longue distance autonomes actuelsSmall fixed-wing Unmanned Aerial Vehicles (UAVs) provide utility to research, military, and industrial sectors at comparablyreasonable cost, but still suffer from both limited operational ranges and payload capacities. Thermal soaring flight for UAVsoffers a significant potential to reduce the energy consumption. However, without remote sensing of updrafts, a glider UAVcan only benefit from an updraft when encountering it by chance. In this thesis, a new framework for autonomous cross-country soaring is elaborated, enabling a glider UAV to visually localize sub-cumulus thermal updrafts and to efficiently gain energy from them.Relying on the Unscented Kalman Filter, a monocular vision-based method is established, for remotely estimatingsub-cumulus updraft parameters. Its capability of providing convergent and consistent state estimates is assessed relyingon Monte Carlo Simulations. Model uncertainties, image processing noise, and poor observer trajectories can degrade theestimated updraft parameters. Therefore, a second focus of this thesis is the design of a robust probabilistic path plannerfor map-based autonomous cross-country soaring. The proposed path planner balances between the flight time and theoutlanding risk by taking into account the estimation uncertainties in the decision making process. The suggested updraftestimation and path planning algorithms are jointly assessed in a 6 Degrees Of Freedom simulator, highlighting significantperformance improvements with respect to state of the art approaches in autonomous cross-country soaring while it is alsoshown that the path planner is implementable on a low-cost computer platform
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Bertrand, Jerome. "Pincement spectral en courbure positive." Phd thesis, Université Paris Sud - Paris XI, 2003. http://tel.archives-ouvertes.fr/tel-00008705.
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Sur l'ensemble des variétés riemanniennes compactes à courbure de Ricci positive (on normalise par $Ric \geq (n-1)g$), la première valeur propre non nulle du laplacien agissant sur les fonctions atteint son minimum uniquement pour la sphère canonique. Dans cette thèse, nous caractérisons, à l'aide de la distance de Gromov-Hausdorff, les variétés riemanniennes à courbure positive dont les premières valeurs propres du laplacien sont proches de celles de la sphère canonique. Cette propriété de minimimalité du spectre de la sphère s'étend par un procédé de symétrisation, au spectre de Dirichlet des boules géodésiques de la sphère parmi les domaines de variétés à courbure de Ricci positive. Nous étudions les domaines de variétés à courbure de Ricci positive dont la première valeur propre de Dirichlet est presque minimimale. En particulier, nous montrons qu'un domaine convexe dont la première valeur propre de Dirichlet est proche de celle d'un hémisphèere est Gromov-Hausdorff proche d'un hémisphère d'un sinus produit tordu.
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Nader, Rafic. "A study concerning the positive semi-definite property for similarity matrices and for doubly stochastic matrices with some applications." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMC210.
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La théorie des matrices s'est développée rapidement au cours des dernières décennies en raison de son large éventail d'applications et de ses nombreux liens avec différents domaines des mathématiques, de l'économie, de l'apprentissage automatique et du traitement du signal. Cette thèse concerne trois axes principaux liés à deux objets d'étude fondamentaux de la théorie des matrices et apparaissant naturellement dans de nombreuses applications, à savoir les matrices semi-définies positives et les matrices doublement stochastiques.Un concept qui découle naturellement du domaine de l'apprentissage automatique et qui est lié à la propriété semi-définie positive est celui des matrices de similarité. En fait, les matrices de similarité qui sont semi-définies positives revêtent une importance particulière en raison de leur capacité à définir des distances métriques. Cette thèse explorera la propriété semi-définie positive pour une liste de matrices de similarité trouvées dans la littérature. De plus, nous présentons de nouveaux résultats concernant les propriétés définie positive et semi-définie trois-positive de certains matrices de similarité. Une discussion détaillée des nombreuses applications de tous ces propriétés dans divers domaines est également établie.D'autre part, un problème récent de l'analyse matricielle implique l'étude des racines des matrices stochastiques, ce qui s'avère important dans les modèles de chaîne de Markov en finance. Nous étendons l'analyse de ce problème aux matrices doublement stochastiques semi-définies positives. Nous montrons d'abord certaines propriétés géométriques de l'ensemble de toutes les matrices semi-définies positives doublement stochastiques d'ordre n ayant la p-ième racine doublement stochastique pour un entier donné p . En utilisant la théorie des M-matrices et le problème inverse des valeurs propres des matrices symétriques doublement stochastiques (SDIEP), nous présentons également quelques méthodes pour trouver des classes de matrices semi-définies positives doublement stochastiques ayant des p-ièmes racines doublement stochastiques pour tout entier p.Dans le contexte du SDIEP, qui est le problème de caractériser ces listes de nombres réels qui puissent constituer le spectre d’une matrice symétrique doublement stochastique, nous présentons quelques nouveaux résultats le long de cette ligne. En particulier, nous proposons d’utiliser une méthode récursive de construction de matrices doublement stochastiques afin d'obtenir de nouvelles conditions suffisantes indépendantes pour SDIEP. Enfin, nous concentrons notre attention sur les spectres normalisés de Suleimanova, qui constituent un cas particulier des spectres introduits par Suleimanova. En particulier, nous prouvons que de tels spectres ne sont pas toujours réalisables et nous construisons trois familles de conditions suffisantes qui affinent les conditions suffisantes précédemment connues pour SDIEP dans le cas particulier des spectres normalisés de SuleimanovaMatrix theory has shown its importance by its wide range of applications in different fields such as statistics, machine learning, economics and signal processing. This thesis concerns three main axis related to two fundamental objects of study in matrix theory and that arise naturally in many applications, that are positive semi-definite matrices and doubly stochastic matrices.One concept which stems naturally from machine learning area and is related to the positive semi-definite property, is the one of similarity matrices. In fact, similarity matrices that are positive semi-definite are of particular importance because of their ability to define metric distances. This thesis will explore the latter desirable structure for a list of similarity matrices found in the literature. Moreover, we present new results concerning the strictly positive definite and the three positive semi-definite properties of particular similarity matrices. A detailed discussion of the many applications of all these properties in various fields is also established.On the other hand, an interesting research field in matrix analysis involves the study of roots of stochastic matrices which is important in Markov chain models in finance and healthcare. We extend the analysis of this problem to positive semi-definite doubly stochastic matrices.Our contributions include some geometrical properties of the set of all positive semi-definite doubly stochastic matrices of order n with nonnegative pth roots for a given integer p. We also present methods for finding classes of positive semi-definite doubly stochastic matrices that have doubly stochastic pth roots for all p, by making use of the theory of M-Matrices and the symmetric doubly stochastic inverse eigenvalue problem (SDIEP), which is also of independent interest.In the context of the SDIEP, which is the problem of characterising those lists of real numbers which are realisable as the spectrum of some symmetric doubly stochastic matrix, we present some new results along this line. In particular, we propose to use a recursive method on constructing doubly stochastic matrices from smaller size matrices with known spectra to obtain new independent sufficient conditions for SDIEP. Finally, we focus our attention on the realizability by a symmetric doubly stochastic matrix of normalised Suleimanova spectra which is a normalized variant of the spectra introduced by Suleimanova. In particular, we prove that such spectra is not always realizable for odd orders and we construct three families of sufficient conditions that make a refinement for previously known sufficient conditions for SDIEP in the particular case of normalized Suleimanova spectra
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Fiori, Costantino. "Oxydation du silicium et modification de l'ordre à courte distance dans les oxydes de silicium induits par un rayonnement laser ultra violet." Grenoble 1, 1986. http://www.theses.fr/1986GRE10131.
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Etude par spectrometrie auger de la structure de la surface de si(111) faiblement recouverte d'oxygene sec. L'irradiation par un faible flux de photons uv induit d'importants rearrangements atomiques dans la phase adsorbees avec formation d'une monocouche tres desordonnee de sio::(2) se transformant en sio::(2) amorphe stable apres un recuit thermique a 949 k. L'irradiation de ces couches par un rayonnement laser uv les rend instables. Formation d'une forte densite de defauts structuraux. Etablissement d'une correlation entre les phenomenes physiques evoques
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Godbout, Martin. "Mesures de distances et de spectres résolus en distance en utilisant les battements hétérodynes entre peignes de fréquences." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27451/27451.pdf.
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Mourgela, Vasiliki. "Conception et implantation d'un dispositif de formation en ligne pour les parents d'enfants avec un trouble du spectre de l'autisme : adaptation en format à distance du programme psychoéducatif "l'A.B.C. du comportement d'enfant ayant un TSA : des parents en action"." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAG003/document.
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L’influence d’Internet est profonde dans la vie personnelle et sociale, mais aussi dans le domaine éducatif. La révolution e-learning décrit la tendance de ces dernières années adoptée par le domaine de la formation. Le domaine de la santé doit s’adapter à cette nouvelle réalité en adoptant des outils numériques et en proposant la formation en ligne. Dans cette perspective, ce projet de recherche décrit le processus d’adaptation d’un programme de formation aux habiletés parentales destiné aux parents d’enfants avec autisme, dans une version en ligne. Ce projet de recherche est une monographie décrivant les étapes nécessaires pour la proposition de ce programme de formation parentale dans une version en ligne. En adoptant la méthode de la recherche design en éducation nous nous basons sur des théories et des concepts pertinents que nous utilisons pour notre contribution pratique ; celle de la conception pédagogique et de l’implantation d’un prototype mis à la disposition des utilisateursThe Internet has deeply influenced our personal and social life, as well as the educational field. The e-learning revolution refers to recent advances in the educational field and the usage of digital tools for teaching and the delivery of educational content. The field of health can profit by adapting to this new reality and by adopting digital tools suitable to offer online training. From this perspective, this research project describes the process of developing an online adaptation of a psycho-educational program targeted to parents of children with autism disorder. This thesis is a monograph describing the steps required to design and implement this training program in an online version. By adopting the method of Educational Design Research, we investigate relevant theories and concepts that are later used to guide our practical contribution : the instructional design and implementation of a prototype, that is implemented and tested with the first users
Books on the topic "Spectre de distance"
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Elliott, James L. New mysteries at Chiron: Final technical report. [Washington, DC: National Aeronautics and Space Administration, 1998.
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Patanè, Giuseppe. An Introduction to Laplacian Spectral Distances and Kernels. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-031-02593-8.
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J, Maddox S., and Aragón-Salamanca A, eds. Wide field spectroscopy and the distant universe: The 35th Herstmonceux Conference, Cambridge, United Kingdom, July 4-8, 1994. Singapore: World Scientific, 1995.
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Greyser, Naomi. “Spectres of Liberty” and the Archive. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190460983.003.0007.
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This epilogue considers the legacy of nineteenth-century sentimentalism, turning to contemporary civic statuary that memorializes nineteenth-century sentimentalists. Juxtaposing this statuary with the hauntingly ephemeral installation The Ghost of Liberty Street Church, the chapter offers postpresentist inquiry as a method that regards the archive as an urgent and poignantly incomplete political project. Where historicist approaches emphasize distance and difference from history through periodization, and charges of presentism name historians’ overidentification with the past, postpresentism holds in view intimacy and distance between past and the present. The epilogue lays out postpresentist readings of sculptures of Harriet E. Wilson in Milford, New Hampshire; Winnemucca Hopkins and Sojourner Truth in the United States Capitol Rotunda; and Elizabeth Cady Stanton, Amelia Bloomer, and Susan B. Anthony in Seneca Falls, New York. These statues’ site-specific installations bring into relief the raced, gendered, and colonial legacies of the grounds beneath their podia and feet.
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Edmunds, D. E., and W. D. Evans. Essential Spectra of General Second-Order Differential Operators. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198812050.003.0010.
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In this chapter, the operators considered are those m-sectorial operators discussed in Chapter VII, and the essential spectra are the sets defined in Chapter IX that remain invariant under compact perturbation. A generalization of a result of Persson is used to determine the least point of the essential spectrum. Davies’ mean distance function is introduced and consequences investigated.
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Patane, Giuseppe. Introduction to Laplacian Spectral Distances and Kernels: Theory, Computation, and Applications. Morgan & Claypool Publishers, 2017.
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Patanè, Giuseppe. Introduction to Laplacian Spectral Distances and Kernels: Theory, Computation, and Applications. Springer International Publishing AG, 2017.
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Patanè, Giuseppe, and Brian A. Barsky. Introduction to Laplacian Spectral Distances and Kernels: Theory, Computation, and Applications. Morgan & Claypool Publishers, 2017.
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Mumenthaler, Christian. Self-correcting distance geometry for the automatic assignment of NMR NOESY spectra and the prediction of protein tertiary structures. 1996.
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Eland, John H. D., and Raimund Feifel. Mainly aliphatic molecules. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198788980.003.0007.
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Double photoionisation spectra of homologous iodides and alcohols, acetonitrile, methyl mercaptan, acetaldehyde, acetone, norbornane, cyclooctatetraene, and TMMD are presented. Effects on the spectra of these molecules from electronic state congestion and geometry changes on ionisation mean that only the lowest dication states can be identified. As little detailed analysis of the individual spectra is possible, this chapter presents the molecules in groups rather than individually. In this chapter, molecules are ordered more thematically than strictly by size. The chapter starts with four homologous iodides and three homologous alcohols. Then this chapter takes some individual molecules with different substituent groups and proceed to a few larger molecules. The chapter demonstrates the dominant effect of the distance to which charges can separate in the dication on the double ionisation threshold.
Book chapters on the topic "Spectre de distance"
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Sun, Rui, and Wanwan Qi. "Quantitative Evaluation of Four Kinds of Site Seismic Response Analysis Methods Using DTW." In Lecture Notes in Civil Engineering, 495–502. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1748-8_43.
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AbstractIn order to quantitatively evaluate the one-dimensional site seismic response analysis methods, this article selected 2418 ground motion records of Japan KiK-net strong-motion seismograph network and 2418 groups of acceleration response spectra calculated by DEEPSOIL, SHAKE2000, SOILQUAKE and SOILRESPONSE, and then` used the dynamic time warping (DTW) algorithm to calculate the DTW distance between the measured acceleration response spectrum and the calculated acceleration response spectrum. The average DTW distance and change trend in different PGA ranges were compared and analyzed. The average DTW distance of the four methods in weak ground motion were similar, and in the strong ground motion, the average DTW distance of SOILRESPONSE was smaller than the other three methods. The DTW distance of the four methods increased with the increase of PGA, the growth rate of SOILRESPONSE was significantly lower than the other three methods. DTW distance can accurately and effectively reflect the difference between response spectrum, which provides a new method for quantitative evaluation of one-dimensional site seismic response analysis method.
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Patanè, Giuseppe. "Discrete Spectral Distances." In An Introduction to Laplacian Spectral Distances and Kernels, 53–69. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-031-02593-8_4.
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Liu, Rong, Hao Zhang, and Oliver van Kaick. "Spectral Sequencing Based on Graph Distance." In Geometric Modeling and Processing - GMP 2006, 630–36. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/11802914_50.
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Torres, Leonardo, Tamer Cavalcante, and Alejandro C. Frery. "Speckle Reduction Using Stochastic Distances." In Progress in Pattern Recognition, Image Analysis, Computer Vision, and Applications, 632–39. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-33275-3_78.
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Reames, Donald V. "High Energies and Radiation Effects." In Solar Energetic Particles, 135–49. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-66402-2_6.
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AbstractIn this chapter we characterize the high-energy spectra of protons that can penetrate shielding and determine the radiation dose to humans and equipment in space. High-energy spectral breaks or “knees”, seen in all large SEP events, determine the contribution of highly penetrating protons. The streaming limit, discussed earlier, places an upper bound on particle fluences early in events and the radial variation of intensities is important for near-solar and deep-space missions. The streaming limit is a strong function of radial distance from the Sun. We also consider requirements for a radiation storm shelter for deep space, a mission to Mars, suitability of exoplanets for life, and radiation-induced chemistry of the upper atmosphere of Earth.
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Wang, Nian, Jun Tang, Jiang Zhang, Yi-Zheng Fan, and Dong Liang. "Spectral Edit Distance Method for Image Clustering." In Advances in Data and Web Management, 350–57. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-72524-4_37.
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Civril, Ali, Malik Magdon-Ismail, and Eli Bocek-Rivele. "SDE: Graph Drawing Using Spectral Distance Embedding." In Graph Drawing, 512–13. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/11618058_48.
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Maeng, Hyunju, Shengcai Liao, Dongoh Kang, Seong-Whan Lee, and Anil K. Jain. "Nighttime Face Recognition at Long Distance: Cross-Distance and Cross-Spectral Matching." In Computer Vision – ACCV 2012, 708–21. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-37444-9_55.
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Hustedt, Eric J., and Albert H. Beth. "Structural Information from CW-EPR Spectra of Dipolar Coupled Nitroxide Spin Labels." In Distance Measurements in Biological Systems by EPR, 155–84. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/0-306-47109-4_3.
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Charlot, Stéphane. "Spectro-Photometric Constraints on Distant Galaxies." In Looking Deep in the Southern Sky, 294–300. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-540-49460-7_55.
Full textConference papers on the topic "Spectre de distance"
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Chbat, M. W., P. R. Prucnal, M. N. Islam, C. E. Soccolich, and J. P. Gordon. "Spectral interference effects in long-distance soliton propagation." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/oam.1992.thss3.
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We have observed experimentally, and modelled both analytically and numerically, the appearance of oscillations in the output spectrum after a reshaped optical soliton has propagated over a few tens of soliton periods in an optical fiber. An optical pulse with sufficient intensity will reshape into a fundamental soliton after propagating a few soliton periods by stripping off the non-soliton part of its energy, which will propagate radiatively in the fiber. This radiative field has a spectrum that is overlapped with the output soliton spectrum, and the phase difference between the two spectra is both frequency and distance dependent. Thus the interference between the two fields will cause a modulation of the output field spectrum, with peaks at discrete frequencies that depend on the distance of propagation. An analytical study, based on the analysis in Ref. 1, gives results in good agreement with the observed spectra. This study, carried for hyperbolic secant-shaped input pulses for which the soliton part of the asymptotic solution of the nonlinear Schrödinger equation is exactly known,2 allows the calculation of the non-soliton field after several soliton periods of propagation, and therefore the spectrum of the total output field. In addition, numerical results obtained by a split-step Fourier transform technique show good agreement with the analytical results.
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Scragg, Carl A. "Spectral Analysis of Ship-Generated Waves in Finite-Depth Water." In ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/omae2002-28510.
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Recent efforts to compare the waves generated by different vessels traveling in finite-depth water have struggled with difficulties presented by various data sets of wave elevations (either measurements or predictions) corresponding to different lateral distances from the ship. Some of the attempts to shift the data to a common reference location have relied upon crude and potentially misleading approximations. The use of free-wave spectral-methods not only overcomes such difficulties, but it also provides us the means to accurately extend CFD results into the far field. As in the deep-water case, one can define a free-wave spectrum that is valid for all lateral positions and distances astern of the vessel. The free-wave spectrum contains a complete description of the Kelvin wake, and wave elevations at any far-field position can be readily calculated once the spectrum is known. For the case of infinitely deep water, Eggers, Sharma, and Ward [1967] presented a method by which free-wave spectra can be determined from appropriate measurements of the far-field wave elevations. The current paper discusses the use of free-wave spectra for finite-depth problems and presents a method for the determination of free-wave spectra based upon fitting predicted wave elevations to a corresponding data set. The predicted wave elevations can be calculated from an unknown distribution of finite-depth Havelock singularities. The unknown singularities are determined by minimizing the mean-square-difference between predicted and measured wave fields. The method appears to be quite general and can be used to calculate either finite or infinite-depth free-wave spectra from experimental data or from local CFD predictions.
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Euán, Carolina, Joaquín Ortega, and Pedro C. Alvarez-Esteban. "Detecting Stationary Intervals for Random Waves Using Time Series Clustering." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-24269.
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The problem of detecting changes in the state of the sea is very important for the analysis and determination of wave climate in a given location. Wave measurements are frequently statistically analyzed as a time series, and segmentation algorithms developed in this context are used to determine change-points. However, most methods found in the literature consider the case of instantaneous changes in the time series, which is not usually the case for sea waves, where changes take a certain time interval to occur. We propose a new segmentation method that allows for the presence of transition intervals between successive stationary periods, and is based on the analysis of distances of normalized spectra to detect clusters in the time series. The series is divided into 30-minutes intervals and the spectral density is estimated for each one. The normalized spectra are compared using the Total Variation distance and a hierarchical clustering method is applied to the distance matrix. The information obtained from the clustering algorithm is used to classify the intervals as belonging to a stationary or a transition period We present simulation studies to validate the method and examples of applications to real data.
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Jia, Qi, and Shouhong Cao. "A Spectrum Matching Algorithm Based on Dynamic Spectral Distance." In 2015 3rd International Conference on Mechatronics and Industrial Informatics. Paris, France: Atlantis Press, 2015. http://dx.doi.org/10.2991/icmii-15.2015.139.
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Wang, Yu, Sufen Li, Yonggang Huo, Jianqing Yang, and Quanhu Zhang. "Explainable Neural Network Algorithm for Rapid Radionuclide Identification Under Low Count Gamma-Ray Spectrum Data." In 2022 29th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/icone29-92829.
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Abstract Real-time and automatic radioisotope identification using gamma spectrum is an important issue in the field of nuclear safety. It is widely used in vehicle mounted radioisotope monitoring, Marine radioisotope monitoring and nuclear decommissioning verification scenarios. At present, the focus of radionuclide identification is fast and stable recognition under low count conditions. In this paper, a radionuclide recognition method based explainable artificial neural network is proposed, and a synthetic gamma spectrum data set is created. The data set contains gamma-ray spectra of 12 different types of radionuclides, which were obtained by Geant4 Monte Carlo simulation software and gaussian broadening of the detector. Data Augmentation was achieved by simulating gamma spectra at different measuring times, different measuring distances and different ambient temperatures. The training results of the neural network optimized by hyperparameter show that it has a high accuracy on the test set with shorter measurement time, longer measurement distance and larger energy spectrum drift range, which provides a method for rapid identification of nuclides in the case of low count. Using t-SNE dimension reduction technology, the twelve dimensions data output by the neural network is reduced to two dimensions for feature visualization, which vividly explains and verifies the recognition results of neural network.
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Gamliel, Avshalom, and Govind P. Agrawal. "Correlation-induced spectral changes in homogeneous and inhomogeneous media." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/oam.1990.tuv5.
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It was recently shown that the spectrum of partially coherent light can change on propagation.1 So far most of the work has applied to propagation in free space and has been limited to far-zone observation points. In this paper we consider the propagation of partially coherent light through homogeneous and inhomogeneous media. Our formulation is based on the analysis of Agrawal et al.,2 which applies to graded-index fibers whose index of refraction changes quadratically as a function of the radial distance from the core center. With this formulation we derive expressions by using the paraxial approximation for the spectrum of the field for arbitrary propagation distances. This allows us to examine the evolution of spectral changes as a function of the propagation distance and the state of coherence of the source. The results for propagation in free space and in homogeneous media are derived by using the appropriate limits. The effects of chromatic dispersion are also investigated by allowing the refractive index to be frequency-dependent.
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Lenz, Georg, and Pierre Meystre. "Resonance fluorescence from two identical atoms in a standing wave." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/oam.1993.mqq.5.
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We have investigated the resonance fluorescence spectrum from two identical atoms driven by a strong standing wave field. We found interesting modifications of the Mollow spectrum, caused by interferences between the two atoms, and in particular a succession of dark and bright states as one of the atoms is moved to successive nodes of the field. Large enough separation between the atoms leads to the disappearance of these interferences, and the atoms act then as independent radiators, the fluorescence spectrum becoming then independent of the interatomic distance. From the point of view advocated by E. Wolf,1 one can interpret these modifications as caused by source correlations. For instance, we obtain new sidebands which are altered as the separation between atoms is modified. When these sidebands eventually cross, the fluorescence spectrum displays interesting properties such as “dark” and “bright” states. These investigations lay the foundations for a discussion of the influence of particle statistics on spectral properties of atoms cooled and trapped in optical molasses. The next step in this direction will include the effects of translational motion on these spectra.2 This program will eventually lead to a full-fledged field theoretical description of the spectral and translational correlation properties of an ensemble of cooled and trapped atoms.
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McKechnie, T. S., and Charles K. Carniglia. "Propagation of the spectral correlation function in a homogeneous medium." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/oam.1988.wp7.
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When two infinitely extensive electromagnetic waves of wavelengths λ1, and λ2propagate in the Fresnel region of a homogeneous medium, the spectral correlation function, 〈 A ( x ′ , y ′ ; λ 1 ) A * ( x , y ; λ 2 ) 〉 , gradually changes with increasing propagation distance. An exact expression is developed which describes these changes. The changes are exhibited in terms of both modulus and phase. In the special case where the two wavelengths are identical, the spectral correlation function reduces to the autocorrelation function. In this case, the function, as expected, is found to conserve during propagation. The paper considers two spectrally well-separated plane waves from the visible part of the spectrum at 450 and 650 nm. Numerical evaluations are given for a typical spectral correlation function that might arise from these waves in conditions of good seeing. It is shown that this spectral correlation function is capable of propagating with a high degree of conservation over distances of the order of the atmospheric depth. It is inferred from this that the spectral correlation function that arises when visible waves pass through the atmosphere is determined only by the accumulated effect of the local atmospheric turbulence; the propagation distance itself makes no significant contribution to the final value attained by the function. This result simplifies the task of describing the statistical properties of polychromatic images formed by large astronomical telescopes. It also offers insights and tools for dealing with the problems associated with laser beam propagation through the atmosphere.
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Dykman, M. I., R. Mannella, P. V. E. McClintock, and N. G. Stocks. "Super-Narrow Spectral Peaks: New Critical Phenomena in Optically Bistable Systems." In Nonlinear Dynamics in Optical Systems. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/nldos.1990.ob266.
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Fluctuation-induced transitions between coexisting attractors in a periodically driven nonlinear system have been investigated theoretically and with an analogue electronic circuit model. Calculations and measurements of power spectral densities of fluctuations have revealed superimposed twin-peaked partial spectra and a super-narrow spectral peak whose intensity depends critically on the distance from the phase transition.
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Robles-Kelly and Hancock. "Edit distance from graph spectra." In ICCV 2003: 9th International Conference on Computer Vision. IEEE, 2003. http://dx.doi.org/10.1109/iccv.2003.1238347.
Full textReports on the topic "Spectre de distance"
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Alchanatis, Victor, Stephen W. Searcy, Moshe Meron, W. Lee, G. Y. Li, and A. Ben Porath. Prediction of Nitrogen Stress Using Reflectance Techniques. United States Department of Agriculture, November 2001. http://dx.doi.org/10.32747/2001.7580664.bard.
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Commercial agriculture has come under increasing pressure to reduce nitrogen fertilizer inputs in order to minimize potential nonpoint source pollution of ground and surface waters. This has resulted in increased interest in site specific fertilizer management. One way to solve pollution problems would be to determine crop nutrient needs in real time, using remote detection, and regulating fertilizer dispensed by an applicator. By detecting actual plant needs, only the additional nitrogen necessary to optimize production would be supplied. This research aimed to develop techniques for real time assessment of nitrogen status of corn using a mobile sensor with the potential to regulate nitrogen application based on data from that sensor. Specifically, the research first attempted to determine the system parameters necessary to optimize reflectance spectra of corn plants as a function of growth stage, chlorophyll and nitrogen status. In addition to that, an adaptable, multispectral sensor and the signal processing algorithm to provide real time, in-field assessment of corn nitrogen status was developed. Spectral characteristics of corn leaves reflectance were investigated in order to estimate the nitrogen status of the plants, using a commercial laboratory spectrometer. Statistical models relating leaf N and reflectance spectra were developed for both greenhouse and field plots. A basis was established for assessing nitrogen status using spectral reflectance from plant canopies. The combined effect of variety and N treatment was studied by measuring the reflectance of three varieties of different leaf characteristic color and five different N treatments. The variety effect on the reflectance at 552 nm was not significant (a = 0.01), while canonical discriminant analysis showed promising results for distinguishing different variety and N treatment, using spectral reflectance. Ambient illumination was found inappropriate for reliable, one-beam spectral reflectance measurement of the plants canopy due to the strong spectral lines of sunlight. Therefore, artificial light was consequently used. For in-field N status measurement, a dark chamber was constructed, to include the sensor, along with artificial illumination. Two different approaches were tested (i) use of spatially scattered artificial light, and (ii) use of collimated artificial light beam. It was found that the collimated beam along with a proper design of the sensor-beam geometry yielded the best results in terms of reducing the noise due to variable background, and maintaining the same distance from the sensor to the sample point of the canopy. A multispectral sensor assembly, based on a linear variable filter was designed, constructed and tested. The sensor assembly combined two sensors to cover the range of 400 to 1100 nm, a mounting frame, and a field data acquisition system. Using the mobile dark chamber and the developed sensor, as well as an off-the-shelf sensor, in- field nitrogen status of the plants canopy was measured. Statistical analysis of the acquired in-field data showed that the nitrogen status of the com leaves can be predicted with a SEP (Standard Error of Prediction) of 0.27%. The stage of maturity of the crop affected the relationship between the reflectance spectrum and the nitrogen status of the leaves. Specifically, the best prediction results were obtained when a separate model was used for each maturity stage. In-field assessment of the nitrogen status of corn leaves was successfully carried out by non contact measurement of the reflectance spectrum. This technology is now mature to be incorporated in field implements for on-line control of fertilizer application.
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Chapman, Martin C., G. A. Bollinger, and Matthew S. Sibol. Modeling Delay-Fired Explosion Spectra and Source Function Deconvolution at Regional Distances. Fort Belvoir, VA: Defense Technical Information Center, September 1992. http://dx.doi.org/10.21236/ada260232.
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Zilberman, Mark. Shouldn’t Doppler 'De-boosting' be accounted for in calculations of intrinsic luminosity of Standard Candles? Intellectual Archive, September 2021. http://dx.doi.org/10.32370/iaj.2569.
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"Doppler boosting / de-boosting" is a well-known relativistic effect that alters the apparent luminosity of approaching/receding radiation sources. "Doppler boosting" alters the apparent luminosity of approaching light sources to appear brighter, while "Doppler de-boosting" alters the apparent luminosity of receding light sources to appear fainter. While "Doppler boosting / de-boosting" has been successfully accounted for and observed in relativistic jets of AGN, double white dwarfs, in search of exoplanets and stars in binary systems it was ignored in the establishment of Standard Candles for cosmological distances. A Standard Candle adjustment appears necessary for "Doppler de-boosting" for high Z, otherwise we would incorrectly assume that Standard Candles appear dimmer, not because of "Doppler de-boosting" but because of the excessive distance, which would affect the entire Standard Candles ladder at cosmological distances. The ratio between apparent (L) and intrinsic (Lo) luminosities as a function of redshift Z and spectral index α is given by the formula ℳ(Z) = L/Lo=(Z+1)^(α-3) and for Type Ia supernova as ℳ(Z) = L/Lo=(Z+1)^(-2). These formulas are obtained within the framework of Special Relativity and may require adjustments within the General Relativity framework.
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White, H. P., W. Chen, and S G Leblanc. Satellite observations for detection of dust from mining activities in a caribou habitat, Northwest Territories and Nunavut. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330548.
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Diamond mining via open pit mining has been ongoing within the Tlicho region of the Northwest Territories for several decades, which includes the habitat range of the Bathurst Caribou Herd. This has led to the importance of quantitative characterization of the Zone Of Influence (ZOI), where resource development activities may be influencing the natural behaviour of the caribou herd in the tundra environment. As part of better defining and understanding the ZOI in this region, an initiative to evaluate the potential of detecting and mapping mine waste rock dust in the surrounding environment is explored. This dust has been shown to coat foliage near roads, influencing the acidity levels of the surficial soil layer and impacting the foliage distribution. To this end, field spectrometry was acquired at various distances from road ways. Satellite imagery from the Proba-1 CHRIS hyperspectral sensor and the multi-spectral Sentinel-2a system were also acquired of the region. This presentation presents the initial spectral analysis pursued to evaluate the potential to remotely spectrally detect waste rock dust material used in road construction in the surrounding tundra vegetation. Initial analysis of the Proba-1 CHRIS hyperspectral imagery shows spectral indicators of fugitive dust and waste rock easily detects the road and suggests detectable dust concentration above ambient up to a distance of under 1km from the road.
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Si, Hongjun, Saburoh Midorikawa, and Tadahiro Kishida. Development of NGA-Sub Ground-Motion Model of 5%-Damped Pseudo-Spectral Acceleration Based on Database for Subduction Earthquakes in Japan. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, December 2020. http://dx.doi.org/10.55461/lien3652.
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Presented within is an empirical ground-motion model (GMM) for subduction-zone earthquakesin Japan. The model is based on the extensive and comprehensive subduction database of Japanese earthquakes by the Pacific Engineering Research Center (PEER). It considers RotD50 horizontal components of peak ground acceleration (PGA), peak ground velocity (PGV), and 5%-damped elastic pseudo-absolute acceleration response spectral ordinates (PSA) at the selected periods ranging from 0.01 to 10 sec. The model includes terms and predictor variables considering tectonic setting (i.e., interplate and intraslab), hypocentral depths (D), magnitude scaling, distance attenuation, and site response. The magnitude scaling derived in this study is well constrained by the data observed during the large-magnitude interface events in Japan (i.e., the 2003 Tokachi-Oki and 2011 Tohoku earthquakes) for different periods. The developed ground-motion prediction equation (GMPE) covers subduction-zone earthquakes that have occurred in Japan for magnitudes ranging from 5.5 to as large as 9.1, with distances less than 300 km from the source.
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Zilberman, Mark. “Doppler de-boosting” and the observation of “Standard candles” in cosmology. Intellectual Archive, July 2021. http://dx.doi.org/10.32370/iaj.2549.
Full textAbstract:
“Doppler boosting” is a well-known relativistic effect that alters the apparent luminosity of approaching radiation sources. “Doppler de-boosting” is the name of relativistic effect observed for receding light sources (e.g. relativistic jets of active galactic nuclei and gamma-ray bursts). “Doppler boosting” changes the apparent luminosity of approaching light sources to appear brighter, while “Doppler de-boosting” causes the apparent luminosity of receding light sources to appear fainter. While “Doppler de-boosting” has been successfully accounted for and observed in relativistic jets of AGN, it was ignored in the establishment of Standard candles for cosmological distances. A Standard candle adjustment of an Z>0.1 is necessary for “Doppler de-boosting”, otherwise we would incorrectly assume that Standard Candles appear dimmer not because of “Doppler de-boosting” but because of the excessive distance, which would affect the entire Standard Candles ladder at cosmological distances. The ratio between apparent (L) and intrinsic (Lo) luminosities as a function of the redshift Z and spectral index α is given by the formula ℳ(Z) = L/Lo=(Z+1)α -3 and for Type Ia supernova appears as ℳ(Z) = L/Lo=(Z+1)-2. “Doppler de-boosting” may also explain the anomalously low luminosity of objects with a high Z without the introduction of an accelerated expansion of the Universe and Dark Energy.
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Zilberman, Mark. PREPRINT. “Doppler de-boosting” and the observation of “Standard candles” in cosmology. Intellectual Archive, June 2021. http://dx.doi.org/10.32370/ia_2021_06_23.
Full textAbstract:
PREPRINT. “Doppler boosting” is a well-known relativistic effect that alters the apparent luminosity of approaching radiation sources. “Doppler de-boosting” is the term of the same relativistic effect observed for receding light sources (e.g.relativistic jets of active galactic nuclei and gamma-ray bursts). “Doppler boosting” alters the apparent luminosity of approaching light sources to appear brighter, while “Doppler de-boosting” alters the apparent luminosity of receding light sources to appear fainter. While “Doppler de-boosting” has been successfully accounted for and observed in relativistic jets of AGN, it was ignored in the establishment of Standard candles for cosmological distances. A Standard candle adjustment of Z>0.1 is necessary for “Doppler de-boosting”, otherwise we would incorrectly assume that Standard Candles appear dimmer, not because of “Doppler de-boosting” but because of the excessive distance, which would affect the entire Standard Candles ladder at cosmological distances. The ratio between apparent (L) and intrinsic (Lo) luminosities as a function of the redshift Z and spectral index α is given by the formula ℳ(Z) =L/Lo=(Z+1)^(α-3) and for Type Ia supernova appears as ℳ(Z)=L/Lo=(Z+1)^(-2). “Doppler de-boosting” may also explain the anomalously low luminosity of objects with a high Z without the introduction of an accelerated expansion of the Universe and Dark Energy.
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Zilberman, Mark. "Doppler De-boosting" and the Observation of "Standard Candles" in Cosmology. Intellectual Archive, July 2021. http://dx.doi.org/10.32370/iaj.2552.
Full textAbstract:
“Doppler boosting” is a well-known relativistic effect that alters the apparent luminosity of approaching radiation sources. “Doppler de-boosting” is the same relativistic effect observed but for receding light sources (e.g. relativistic jets of AGN and GRB). “Doppler boosting” alters the apparent luminosity of approaching light sources to appear brighter, while “Doppler de-boosting” alters the apparent luminosity of receding light sources to appear fainter. While “Doppler de-boosting” has been successfully accounted for and observed in relativistic jets of AGN, it was ignored in the establishment of Standard candles for cosmological distances. A Standard Candle adjustment of Z>0.1 is necessary for “Doppler de-boosting”, otherwise we would incorrectly assume that Standard Candles appear dimmer, not because of “Doppler de-boosting” but because of the excessive distance, which would affect the entire Standard Candles ladder at cosmological distances. The ratio between apparent (L) and intrinsic (Lo) luminosities as a function of the redshift Z and spectral index α is given by the formula ℳ(Z) = L/Lo=(Z+1)α -3 and for Type Ia supernova appears as ℳ(Z) = L/Lo=(Z+1)-2. “Doppler de-boosting” may also explain the anomalously low luminosity of objects with a high Z without the introduction of an accelerated expansion of the Universe and Dark Energy.
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Keahava, N. Distance Metrics and Band Selection in Hyperspectral Processing with Applications to Material Identification and Spectral Libraries. Fort Belvoir, VA: Defense Technical Information Center, December 2002. http://dx.doi.org/10.21236/ada409023.
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Lasko, Kristofer, Francis O’Neill, and Elena Sava. Automated mapping of land cover type within international heterogenous landscapes using Sentinel-2 imagery with ancillary geospatial data. Engineer Research and Development Center (U.S.), September 2024. http://dx.doi.org/10.21079/11681/49367.
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A near-global framework for automated training data generation and land cover classification using shallow machine learning with low-density time series imagery does not exist. This study presents a methodology to map nine-class, six-class, and five-class land cover using two dates of a Sentinel-2 granule across seven international sites. The approach uses a series of spectral, textural, and distance decision functions combined with modified ancillary layers to create binary masks from which to generate a balanced set of training data applied to a random forest classifier. For the land cover masks, stepwise threshold adjustments were applied to reflectance, spectral index values, and Euclidean distance layers, with 62 combinations evaluated. Global and regional adaptive thresholds were computed. An annual 95th and 5th percentile NDVI composite was used to provide temporal corrections to the decision functions, and these corrections were compared against the original model. The accuracy assessment found that the regional adaptive thresholds for both the two-date land cover and the temporally corrected land cover could accurately map land cover type within nine-class, six-class, and five-class schemes. Lastly, the five-class and six-class models were compared with a manually labeled deep learning model (Esri), where they performed with similar accuracies. The results highlight performance in line with an intensive deep learning approach, and reasonably accurate models created without a full annual time series of imagery.