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Letteratura scientifica selezionata sul tema "Techniques à N corps"

Autore: Grafiati

Pubblicato: 7 dicembre 2024

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Articoli di riviste sul tema "Techniques à N corps"

Andrieu, Bernard. "Disparition du sujet dans son corps". Figures de l'Art. Revue d'études esthétiques 4, n. 1 (1999): 67–83. http://dx.doi.org/10.3406/fdart.1999.1188.

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Le corps est devenu le moyen pour le sujet de trouver son identité. La fin des utopies collectives aura rabattu le sujet sur une économie et une esthétique de la surface et de la profondeur. Le retour en Occident des techniques de percement et de tatouage n’ est pas seulement un goût exotique du tribalisme. Il indique la naissance de nouveaux modes d’incarnation du corps. Mais cette incarnation novatrice est attaquée par les penseurs du déchantement qui ne cessent d’annoncer la disparition du sujet.

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Neatrour, Matthew A., Robert H. Jones e Stephen W. Golladay. "Assessment of Nutrient Limitation in Floodplain Forests with Two Different Techniques". Research Letters in Ecology 2008 (2008): 1–4. http://dx.doi.org/10.1155/2008/260754.

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We assessed nitrogen and phosphorus limitation in a floodplain forest in southern Georgia in USA using two commonly used methods: nitrogen to phosphorus (N:P) ratios in litterfall and fertilized ingrowth cores. We measured nitrogen (N) and phosphorus (P) concentrations in litterfall to determine N:P mass ratios. We also installed ingrowth cores within each site containing native soil amended with nitrogen (N), phosphorus (P), or nitrogen and phosphorus (N + P) fertilizers or without added fertilizer (C). Litter N:P ratios ranged from 16 to 22, suggesting P limitation. However, fertilized ingrowth cores indicated N limitation because fine-root length density was greater in cores fertilized with N or N + P than in those fertilized with P or without added fertilizer. We feel that these two methods of assessing nutrient limitation should be corroborated with fertilization trials prior to use on a wider basis.

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Monette, Julie, e France Gravelle. "Perspectivas y retos de la relación pedagógica en la enseñanza a distancia: Resumen de la tesis de máster de Monette (2022)". Médiations et médiatisations, n. 17 (22 aprile 2024): 115–19. http://dx.doi.org/10.52358/mm.vi17.405.

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Cette note de lecture résume les principales conclusions d’un mémoire de maîtrise portant sur la relation pédagogique en formation à distance (FAD). Les résultats de cette recherche démontrent qu’en contexte de FAD, bien que plus de la moitié du corps enseignant (n = 73) considère la relation comme satisfaisante, la majorité estime que la distance impacte négativement cette dynamique. Confrontées aux défis liés à la distance physique ou aux limitations techniques, les personnes enseignantes déploient diverses stratégies innovantes pour favoriser un climat de classe positif, une présence accrue et une qualité relationnelle optimale. Les résultats de cette recherche soulèvent des questions sur la FAD, soulignant l’importance d’ajuster les pratiques éducatives tout en préservant la qualité de la relation pédagogique.

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Fang, Qizhi, e Shanfeng Zhu. "LINEAR AND INTEGER PROGRAMMING TECHNIQUES FOR COOPERATIVE GAMES". International Journal of Foundations of Computer Science 13, n. 05 (ottobre 2002): 653–66. http://dx.doi.org/10.1142/s0129054102001357.

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Let Γ = (N, v) be a cooperative game with the player set N and value function v : 2N → R. A solution of the game is in the core if no subset of players could gain advantage by breaking away from the grand coalition of all players. This paper surveys theoretical results on the cores for some cooperative game models. These results proved that the linear program duality characterization of the core is a very powerful tool. We will focus on linear and integer programming techniques applied in this area.

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Garnier, Marie. "Correcting erroneous N+N structures in the productions of French users of English". EuroCALL Review 20, n. 1 (22 marzo 2012): 70. http://dx.doi.org/10.4995/eurocall.2012.16050.

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This article presents the preliminary steps to the implementation of detection and correction strategies for the erroneous use of N+N structures in the written productions of French-speaking advanced users of English. This research is carried out as part of the grammar checking project CorrecTools, in which errors are detected and corrected using linguistic-based NLP techniques. We use information from comprehensive and student grammars as well as the results of linguistic research in order to identify a set of constraints on the formation of N+N structures. We use these constraints to propose a classification of the N+N errors found in our corpus and design detection and correction strategies for each error type.

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De Giovanni, Cosimo. "Le palimpseste collocationnel : mécanismes productifs de formation des collocations métaphoriques V + N". NEO 32 (23 dicembre 2020): 210–32. http://dx.doi.org/10.31261/neo.2020.32.12.

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In this article we argue in favor of a useful model to explain the productive mechanisms of formation of verb + noun metaphorical collocations. We postulate that verbo-nominal collocations, relating to human activities and relating to the fields of techniques, crafts, art and manufactures constitute a model for the metaphorical collocations. We will apply our model to metaphorical collocations with the French verb forger. For the application of our model, a corpus analysis will be necessary.

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Reddy, V. Mohan, John R. Liddicoat, Doff B. McElhinney, Michael M. Brook, Jacques A. M. van Son e Frank L. Hanley. "Biventricular repair of lesions with straddling tricuspid valves using techniques of cordal translocation and realignment". Cardiology in the Young 7, n. 2 (aprile 1997): 147–52. http://dx.doi.org/10.1017/s1047951100009380.

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AbstractSurgical Management of straddling tricuspid valve and associated defects is a complex problem. Between August 1992 and August 1995, 5 patients with major straddling of the tricuspid valve underwent a complete or partial biventricular repair. All patients had either an inlet ventricular septal defect (n=4) or a ventricular septal defect with an inlet component (n=1), Co-existing cardiac lesions included hypoplasia of the right ventricle (n=3), discordant ventriculoarterial connections (n=1), tetralogy of Fallot (n=1), and multiple muscular vetricular septal defects (n=2). At the time of presentation to our institution, two of these patients had previously been palliated in preparation for a Fontan procedure, having undergone construction of a bidirectional superior cavopulmonary shunt. One patient was referred specifically for a Fontan procedure. The tricuspid valve was repaired by transecting all of the straddling cords and reattaching them in the right ventricle or onto the right side of the patch used to close the ventricular septal defect. Associated procedures included closure of the septum in all patients, an arterial switch procedure in one, repair of tetralogy of Fallot in one, and construction of a bidirectional superior cavopulmonary shunt in one. There has been no early or late mortality. Complete heart block requiring insertion of a pacemaker occurred after surgery in three patients. At a median follow-up of 32 months, functional integrity of the tricuspid valve is well maintained, with only one patient having moderate tricuspid regurgitation. None of the patients are receiving any cardiac medication.

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Bednarek, Monika. "Analysing intra-textual patterns in corpus-assisted discourse studies". Journal of Corpora and Discourse Studies 7 (27 maggio 2024): 43–62. http://dx.doi.org/10.18573/jcads.113.

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Many corpus-based discourse analysts are interested in linguistic patterns that hold across the texts in their corpus. In such corpus-based studies, relatively little attention is given to ‘intra-textual’ patterns or discourse organisation/text structure. For example, a standard practice in corpus-assisted discourse studies is to generate lists of word frequencies, keywords, collocates, and n-grams on the basis of total word frequencies in the corpus, without analysing how these words are used to structure texts or conversations. In this commentary, I reflect on this issue, and introduce selected techniques for integrating analysis of text structure/discourse organisation in corpus-assisted discourse studies, including the analysis of dispersion/concordance plots in media data, the use of clusters/n-grams across sentence breaks in conversational data, and the repurposing of parallel concordances for analysing Twitter posts and responses to them.

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Fiestas, Jose A., e Rainer Spurzem. "Dynamics of Black Holes in Rotating Cores". Proceedings of the International Astronomical Union 5, S267 (agosto 2009): 328. http://dx.doi.org/10.1017/s1743921310006587.

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We study the dynamical interaction between stars surrounding black holes in self-gravitating galaxy cores by using realistic N-body techniques, calibrated by Fokker–Planck approximated models (Fiestas, Spurzem, & Kim 2006). We study the evolution over the relaxation time (collisional nuclei) of non-spherical (triaxial) models as flattening of the system due to rotation is allowed. We follow the interplay between velocity diffusion due to relaxation and black hole star accretion and study accretion rates and cusp formation in spherically symmetric and axisymmetric models.

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Αηδονά, Ε., Δ. Κοντοπούλου e R. Scholger. "RE-ORIENTANTION METHODS OF CORE SAMPLES: IMPLICATIONS TO SEDIMENT CORES FROM N. GREECE". Bulletin of the Geological Society of Greece 36, n. 3 (1 gennaio 2004): 1194. http://dx.doi.org/10.12681/bgsg.16462.

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The different methods of re-orientation of core samples are discussed in the present study. In order to obtain results from core samples concerning the direction of the formation, their permeability and their anisotropy, it is essential first to bring all the pieces of the core into their initial position with regard to the North and to the horizontal (in-situ). In this study we emphasize particularly to the palaeomagnetic technique. This re-orientation method uses the magnetic components of the rocks (especially the viscous component) in order to determine the direction with regard to the North (declination). Also, the anisotropy method which helps us to correct the angle to the horizontal (inclination) is described here. Finally we applied the last two methods in non-oriented core samples from N. Greece and the significant importance of the re-orientation techniques to the palaeomagnetic studies is shown.

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Più fonti

Tesi sul tema "Techniques à N corps"

Molineri, Anaïs. "Un nouveau dispositif pour étudier la relaxation d'un système quantique à N corps". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLO013/document.

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Les travaux présentés dans ce manuscrit de thèse portent sur la construction d'une nouvelle expérience d'atomes froids de strontium 84, depuis ses balbutiements jusqu'à l'obtention des pièges magnéto-optiques sur la raie large à 461 nm, puis sur la raie étroite à 689 nm.Les études menées avec cette expérience porteront sur la dynamique de relaxation de gaz quantiques placés initialement en situation hors-équilibre. Pour réaliser de telles expériences, un microscope à atomes sera mis en place prochainement et permettra de mesurer des fonctions de corrélations spatiales à partir de la répartition des atomes dans le piège optique bidimensionnel. C'est pourquoi, en parallèle du montage, des travaux ont été réalisés pour mettre au point un algorithme de reconstruction, indispensable au traitement des futures images obtenues par ce microscope. Ce manuscrit de thèse a pour objectif de détailler et justifier aussi précisément que possible les choix expérimentaux qui ont été effectués et de présenter le stade actuel d'avancement de l'algorithme de reconstruction d'images. Il reste encore quelques étapes de construction avant que le dispositif expérimental soit achevé: ajouter une chambre dans laquelle les mesures auront lieu, mettre en place le système d'imagerie et monter le système optique qui permettra de transporter les atomes entre les chambres à vide, les confiner dans un plan, d'effectuer la transition vers un condensat de Bose-Einstein et enfin les soumettre à un réseau optique bidimensionnel
This manuscript presents the first steps of a new ultracold atoms experiment using strontium 84. The aim of this experiment is to study the relaxation dynamics of quantum gases initially prepared in an out-of-equilibrium state. This experiment will include a quantum gas microscope, allowing us to measure spatial correlation functions in two-dimensionnal systems. The current state of the construction allows us to generate both magneto-optical trap of strontium: along its wide transition at 461 nm and its narrow transition at 689 nm. Concurrently with the experimental setup, we carried out works on a reconstruction algorithm required for the future data processing of the microscope images. This manuscript details experimental aspects, justifying their choices, and presents the current state of work on the reconstruction algorithm. There are still steps to complete the experimental setup: add a chamber where we will make the measurements to the vaccuum system, set up the quantum gaz microscope and all the required optics to transport the atomic clouds between two vaccuum chambers, to reach Bose-Einstein condensation and to confine the atoms in two-dimensionnal optical traps

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Roux, Antoine. "Emulation of PGCM calculations using the Eigenvector continuation method". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP114.

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Le noyau atomique, système quantique de nucléons en interaction, constitue un problème difficle à résoudre exactement. Pour contourner cette difficulté, des méthodes de résolution approchées on été introduites, comme la Projected Generator Coordinate Method (PGCM). La force de la PGCM est de construire un espace de faible dimension, motivé par des considérations physiques, dans lequel trouver un solution approchée est facile. Cependant, le coût numérique du calcul d'un espace PGCM rend cette méthode mal adaptée pour une étude statistique de sensibilité des observables nucléaires vis-à-vis des paramètres du modèle d'interaction, laquelle nécessite un grand nombre de calculs PGCM. Afin de rendre ce type d'études possibles, cette thèse explore la notion d'émulateur PGCM. Dans ce travail, une combinaison de PGCM avec la méthode Eigenvector Continuation (EC) est construite et étudiée. Cette combinaison (l'émulateur PGCM-EC) tire parti des ressemblances formelles entre PGCM et EC, et surtout de la possibilité de décomposer l'hamiltonien comme combinaison linéaire de termes indépendants des paramètres du modèle d'interaction. Cette dernière propriété permet de concentrer la plus grande partie du coût numérique sur le calcul de quantités indépendantes des paramètres de l'interaction (les kernels élémentaires), et ainsi rend possible l'émulation massive de calculs PGCM, au prix d'avoir en amont effectué le calcul très lourd des kernels élémentaires. Les limites de cet émulateur sont aussi étudiées, en introduisant notamment la notion de sur-entraînement, qui provient précisément du fait que la PGCM est une méthode non-exacte de résolution du problème à N-corps nucléaire. Cette thèse démontre au final qu'il est possible d'émuler des millions de calculs PGCM avec une erreur ne dépassant pas 3% sur la spectroscopie collective des noyaux, et avec un faible coût numérique représentant une fraction de 1% du coût des millions de calculs PGCM
An atomic nucleus is a quantum system of interacting nucleons and constitutes a problem difficult to solve exactly. For this reason, a diversity of approximate resolution methods has been designed, and Projected Generator Coordinate Method (PGCM) is one of them. The strong point of PGCM is to construct a physically inspired small dimensional space, in which an approximate solution of the nuclear many-body problem is easily found. However the numerical cost of PGCM space computation make this method inadapted for sensibility analysis of nuclear observables with restect to parametrisation of the interaction model, this analysis requiring an huge number of PGCM computations. In order to make this type of study possible, this thesis explore the concept of PGCM emulator. In this work, a combination of PGCM with Eigenvector Continuation (EC) is constructed and studied. This combination (the PGCM-EC emulator) takes advantage of mathematical similarities between PGCM and EC, and above all of the decomposition of the hamiltonian as a linear combination of parameter-independent terms. The latter property is used to concentrate the heavier numerical cost in the computation of parameter-independent quantities (the elementary kernels), and open the feasability of massive PGCM emulations, the price being having first-handedly computed the costly elementary kernels. Limits of the emulator are also explored, by introducing the concept of over-training, which is exactly a consequence of the aproximativeness of a PGCM computation. Eventually this thesis demonstrates the possibility to emulate millions of PGCM computations with an error on collective spectroscopy less than 3%, and with a low numerical cost fraction of 1% of the million PGCM calculations cost

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Martin-Fardon, Rémi. "Effets comparés de traitements chroniques par la cocai͏̈ne et la N-[1-(2-benzo(B)thiophényl)cyclohexyl]pipéridine (BTCP), sur la concentration extracellulaire de dopamine dans le striatum de rat". Montpellier 2, 1996. http://www.theses.fr/1996MON20186.

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La microdialyse repetee chez un meme animal permet la mesure a long terme de la concentration de dopamine (da) extracellulaire (dae, 10 fois sur une periode de 23 jours) dans le striatum. La cocaine et la btcp sont des inhibiteurs de la recapture de la da. Aux doses respectives de 20 et 10 mg/kg elles ont des effets comportementaux et sur le niveau de base de da dans le striatum et le nucleus accumbens, similaires. La dialyse repetee a ete appliquee a la mesure d'effets de traitements chroniques (tch) par la cocaine (20 mg/kg), la btcp (10 mg/kg) et croises (tcr). Le premier jour du tch, les deux drogues ont le meme effet sur la quantite totale de da. Pendant le traitement par la cocaine, la dae augmente jusqu'a 297% (jour 7) et revient a la valeur initiale a partir du jour 13. Lors de traitements par la btcp, la dae ne varie pas. La quantite totale de da collectee apres l'administration des deux drogues evolue parallelement a la dae. Apres une semaine de sevrage, les deux drogues ont un effet similaire a celui du premier jour. Lors du tcr, le pre-traitement par la btcp previent l'augmentation de la dae induite par la cocaine et en partie son effet sur la quantite totale de da. Chez des rats pre-traites par la cocaine, la btcp reverse les effets de la cocaine. Au cours des tcr, le jour de la substitution les pre-traitements sensibilisent a l'effet de l'autre drogue. Les effets de la cocaine peuvent etre assimiles a une sensibilisation et ceux de la btcp a une tolerance. Les effets de la btcp pourraient permettre d'envisager une pharmacotherapie de la dependance a la cocaine

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Beck, Arnaud. "Simulation N-Corps d'un plasma". Phd thesis, Observatoire de Paris, 2008. http://tel.archives-ouvertes.fr/tel-00359057.

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La simulation N-Corps d'un plasma consiste à calculer l'interaction coulombienne mutuelle entre N particules chargées. Nous avons adapté un algorithme N-Corps de type ``code en arbre'', utilisé avec succès dans le cas gravitationnel, pour la simulation de plasmas. Pour l'instant, nous avons trouvé deux champs d'applications pour lesquels cette technique est particulièrement bien adaptée.

Tout d'abord les problèmes d'expansion de plasma dans le vide. Ce genre de simulation fait coexister des densités d'ordres de grandeur très différents. Certaines zones peuvent avoir un comportement hydrodynamique pendant que d'autres sont peuplées de particules avec des trajectoires balistiques car trop énergétiques. Les protons, notamment, peuvent ainsi être accélérés à des vitesses requises pour la fusion. Ce type de problème, faisant intervenir une interface plasma-vide, est pratiquement impossible à étudier à l'aide des techniques de simulation courantes (e.g. codes MHD, Vlasov, Fokker-Planck, ...).

L'autre champ d'application est celui de la simulation des plasmas modérément ou fortement couplés qui concerne de nombreux plasmas de laboratoire, mais également des plasmas astrophysiques, tels, par exemple, la zone convective du Soleil. Dans les plasmas dits couplés, les collisions ``binaires proches'' entre charges ne peuvent pas être négligées. Or, les modèles numériques de type Fokker-Planck, très majoritairement utilisés pour simuler des plasmas faiblement collisionnels, n'en tiennent pas compte ce qui les rends inadéquats à ce type de plasma. La technique N-Corps, quant à elle, gère chaque particule individuellement et peut très bien décrire précisément les trajectoires de particules subissant ce genre de déviation violente.

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Beck, Arnaud. "Simulation N-Corps d'un plasma". Phd thesis, Observatoire de Paris (1667-....), 2008. https://theses.hal.science/tel-00359057.

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La simulation N-Corps d’un plasma consiste à calculer l’interaction coulombienne mutuelle entre N particules chargées. Nous avons adapté un algorithme N-Corps de type “code en arbre”, utilisé avec succès dans le cas gravitationnel, pour la simulation de plasmas. Pour l’instant, nous avons trouvé deux champs d’applications pour lesquels cette technique est particulièrement bien adaptée. Tout d’abord les problèmes d’expansion de plasma dans le vide. Ce genre de simulation fait coexister des densités d’ordres de grandeur très différents. Certaines zones peuvent avoir un comportement hydrodynamique pendant que d’autres sont peuplées de particules avec des trajectoires balistiques car trop énergétiques. Les protons, notamment, peuvent ainsi être accélérés à des vitesses requises pour la fusion. Ce type de problème, faisant intervenir une interface plasma-vide, est pratiquement impossible à étudier à l’aide des techniques de simulation courantes (e. G. Codes MHD, Vlasov, Fokker-Planck,. . . ). L’autre champ d’application est celui de la simulation des plasmas modérément ou fortement couplés qui concerne de nombreux plasmas de laboratoire, mais également des plasmas astrophysiques, tels, par exemple, la zone convective du Soleil. Dans les plasmas dits couplés, les collisions “binaires proches” entre charges ne peuvent pas être négligées. Or, les modèles numériques de type Fokker-Planck, très majoritairement utilisés pour simuler des plasmas faiblement collisionnels, n’en tiennent pas compte ce qui les rends inadéquats à ce type de plasma. La technique N-Corps, quant à elle, gère chaque particule individuellement et peut très bien décrire précisément les trajectoires de particules subissant ce genre de déviation violente
The N-Body plasma simulation consists in calculating the Coulomb interaction between N charged particles. We adapted an N-Body “tree code” algorithm, successfully used in the gravitational case, for the simulation of plasma. So far, we have found two main applications which suits this technique particularly well. First, the expansion of a plasma into vacuum. In this kind of simulations, densities of very different order of magnitude have to interact. Some areas can have an hydrodynamic behavior whereas some others are filled by energetic particles following ballistic trajectories. Problems which take into account plasma-vacuum interface are almost impossible to study with common simulation techniques ( Vlasov, Fokker-Planck). The other application consists in simulating moderatly or strongly coupled plasma. It deals with many laboratory plasmas as well as astrophysical plasmas such as the convective zone of the sun. In coupled plasmas, close collisions between charges can not be neglected as it is done in most of the other simulation techniques. The N-Body technique allows the accurate description of the trajectory of each single particle and thus to take into account the strong deviations

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ALBOUY, ALAIN. "Varietes integrales du probleme des n corps". Paris 7, 1992. http://www.theses.fr/1992PA077213.

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Les varietes integrales d'un systeme differentiel sont les varietes invariantes obtenues en fixant la valeur des integrales premieres connues. La partie d de cette these donne une description de la variete integrale du probleme des trois corps qui convainc qu'on rencontre exactement 8 valeurs de l'energie pour lesquelles sa topologie change, lorsqu'on fixe le moment cinetique a une valeur arbitraire non nulle et qu'on fait decroitre l'energie en partant de l'infini. La partie c demontre qu'on rencontre au plus 8 valeurs. Deux phenomenes distincts sont responsables de ces changements de topologie: les points critiques de la fonction energie restreinte au niveau choisi du moment cinetique et les points critiques a l'infini de cette meme fonction. Le premier est responsable des 4 dernieres valeurs rencontrees. Les points critiques s'identifient aux equilibres relatifs exhibes par lagrange. C'est a l'etude du second phenomene qu'est consacree cette partie, dans le cadre general du probleme des n corps dans l'espace. On montre qu'il est associe a une division du systeme de particules en amas, et que chaque amas est un equilibre relatif. La partie b etudie les niveaux du moment cinetique d'un systeme de n corps, et traite de maniere globale la question de la reduction ou elimination des nuds

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Damak, Mondher. "C*-algebres et probleme a n-corps". Cergy-Pontoise, 2000. http://www.theses.fr/2000CERG0091.

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Le but de cette these est l'etude par des methodes algebriques de certaines generalisations du probleme a n-corps. Notre point de vue est, au depart, celui des chapitres 8 et 9 de abg. Nous montrons dans un premier article (constituant le chapitre 2 de cette these) que les techniques abstraites developpees dans ce livre permettent de retrouver et d'ameliorer les resultats de c. Gerard sur les hamiltoniens dispersifs. Nous montrons aussi que le resultat de lewis, siedentop and vugalter concernant le spectre essentiel des systemes a n particules relativistes decoule facilement de la version algebrique du theoreme hvz de abg. Dans les chapitres 3 et 4 de la these nous allons au-dela du formalisme algebrique pour les systemes a n corps tel qu'il est expose dans le chapitre 9 de abg. Ces deux parties constituent en fait deux papiers en collaboration avec vladimir georgescu. Notre but est d'etudier des c*-algebres d'operateurs suggerees par le probleme a n corps mais en meme temps naturellement associees a des espaces vectoriels de dimensions finies, et de faire l'analyse spectrale des operateurs auto-adjoints qui leurs sont affilies. Cette classe d'operateurs est tres riche, elle permet par exemple de traiter de maniere unifiee les hamiltoniens des systemes dispersifs (avec des interactions dependantes du moment) et ceux des systemes stratifies ou pluristratifies. Abg w. Amrein, a. Boutet de monvel and v. Georgescu, c 0-groups, commutator methods and spectral theory of n-body hamiltonians (birkhauser, progress in math. Ser. Nr. 135, 1996).

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Roccia, Jérome. "Densité de niveaux du problème a n-corps". Paris 11, 2007. http://www.theses.fr/2007PA112136.

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Nous étudions la densité de niveaux du problème à N-corps (rho_MB) pour des gaz de fermions et de bosons en fonction de la température et du nombre de particules. Nous avons discuté des termes correctifs dus aux effets de nombre fini de particules : alors que le cas des bosons est très riche, il semble qu'un seul comportement apparaisse pour des fermions. Une expression semiclassique de rho_MB pour deux types de particules avec un moment angulaire a été proposé. Celle-ci se compose d'une partie lisse provenant de la méthode du point de col avec des termes correctifs dus au développement de l'expression exacte du nombre de partition pour deux types de particules, et d'une partie oscillante issue des fluctuations de la densité de niveaux à une particule. Une étude numérique pour valider notre modèle a été menée. Dans le cas du noyau atomique, la partie oscillante de rho_MB est contrôlée par un facteur de température qui dépend de la dynamique du système (chaotique ou intégrable) et de la partie oscillante de l'énergie du fondamental. Nous donnons alors l'expression générale de la valeur moyenne de l'énergie pour des potentiels fixes. Le cas auto-cohérent est abordé via l'oscillateur harmonique à trois dimensions (HO3D). L'homologue bosonique de la partie oscillante de rho_MB à basse température a été discuté pour des billards et pour le HO3D isotrope. Dans ce cas il n'y a plus d'oscillation, mais une correction en loi d'échelle. Dans le cas de HO3D isotrope, ces corrections sont de l'ordre de la partie lisse. Dans la limite haute température, nous montrons que la partie oscillante de rho_MB est exponentiellement négligeable comparée au terme lisse
We investigate the many-body level density rho_MB for fermion and boson gases. We establish its behavior as a function of the temperature and the number of particules. We deal with correction terms due to finite number of particles effects for rho_MB : for fermions, it seems that it exists only one behavior whereas the case of bosons. Besides we propose a semiclassical expression of rho_MB for two types of particules with an angular momentum. It is decomposed into a smooth part coming from the saddle point method plus corrective terms due to the expansion of the number of partitions for two types of particles and an oscillating part coming from the fluctuations of the single-particle level density. Our model is validated by a numerical study. For the case of the atomic nucleus, the oscillating part of rho_MB is controled by a temperature factor which depends on the chaotic or integrable nature of the system and depends on the fluctuation of the ground state energy. This leads to consider in more detail this last quantity. For an isolated system, we give the general expression of the mean value for fixed potentials. We treat the self-bound system case through the example of the three dimensional harmonic oscillator (3DHO). Furthermore we study the oscillating part of rho_MB for bosons in the low temperature regime for billiards and for isotropic 3DHO. We note the oscillations disappear leading to a power law correction. In the case of the isotropic 3DHO, these corrections have the same order of magnitude as the smooth part. In the same way, for the high temperature regime we show the oscillating part of rho_MB is exponentially negligeable compared to the smooth part

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Dabholkar, Bhupen Dilip. "Étude numérique des systèmes à N corps contraints". Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSES068.

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Cette thèse présente une étude numérique de trois modèles de physique à N corps soumis à des contraintes directes ou indirectes. La présence de contraintes dans un système complexe à plusieurs corps requiert des algorithmes numériques non triviaux pour les étudier. Les deux premiers modèles comportent une forme directe de contrainte locale et sont le modèle de Dimères Quantiques (QDM) de Rokhsar-Kivelson et un modèle de mécanique statistique classique de boucles sans croisement avec des interactions attractives, tous les deux étudiés sur un réseau carré. L'étude de tels modèles contraints a connu un regain d'intérêt récemment avec leur réalisations directes sur des simulateurs quantiques de réseaux d'atomes de Rydberg. Les simulations du modèle classique utilisent l'algorithme Monte Carlo de boucles dirigées (Directed loop algorithm) tandis que le QDM nécessite un nouveau schéma de Monte Carlo quantique basé sur le cadre des expansions en séries stochastiques appelé Sweeping Cluster Algorithm (SCA). Nous présentons une modification du SCA pour rendre les simulations ergodiques à température finie. Notre étude numérique montre l'existence d'une phase critique dans les deux modèles séparée par une transition de phase à température finie vers une phase ordonnée de dimères ou de boucles qui brise spontanément certaines symétries du réseau. Nous montrons que dans le cas où les interactions sont attractives, cette transition de phase est de type Kosterlitz-Thouless et peut être comprise en construisant une théorie des champs de hauteurs. Le diagramme de phase à température finie du QDM présente quant à lui une ré-entrance inhabituelle dans la phase critique. La partie finale de cette thèse traite du rôle des symétries non-abéliennes dans les processus de thermalisation des systèmes quantiques. Nous étudions les états propres de haute énergies d'une chaîne de spins désordonnée avec une symétrie SU(3). Le modèle n'a pas directement de contraintes mais nous effectuons une diagonalisation exacte dans une base contrainte de tableaux de Young en utilisant la symétrie SU(3) complète de ce modèle. En examinant les sondes couramment utilisées pour la thermalisation (statistiques spectrales, distribution des observables locales et entropie d'intrication), nous montrons que le modèle présente un régime non ergodique sur une grande plage de tailles de système pour un désordre fort, contrastant avec la thermalisation rapide observée à faible désordre
This thesis presents computational studies of three different models of many-body physics with direct or indirect constraints. The presence of constraints in complex many-body systems calls for non-trivial numerical algorithms to study them. The first two models which have a direct form of local constraint are the Rokhsar-Kivelson Quantum Dimer model (QDM) and a classical statistical mechanics model of non-intersecting loops with attractive interactions, both on the square lattice. The investigations of such constrained models have found a recent resurgence with their direct realizations on Rydberg atom arrays quantum simulators. The study of the classical model uses a Monte Carlo directed loop algorithm while the QDM calls for a novel Quantum Monte Carlo scheme based on the framework of Stochastic Series Expansions called the Sweeping Cluster Algorithm (SCA). We present a modification of the SCA in order to render simulations fully ergodic at finite temperature. For both models, our numerical studies show the existence of a critical phase separated by a phase transition at finite temperature to an ordered phase of dimers or loops which spontaneously breaks certain lattice symmetries. We show that for the case where the interaction is attractive this phase transition is of Kosterlitz-Thouless type and can be understood by constructing a coarse-grained field theory through a height mapping. The finite temperature phase diagram of the QDM presents an unusual re-entrance behavior in the critical phase. The final part of this thesis deals with the role of non-abelian symmetries in the thermalization process of quantum many-body systems. We study the high-energy eigenstates of a SU(3) symmetric spin chain in presence of disorder. While the model does not directly have constraints, we perform exact diagonalization in a constrained basis of Young tableau making use of the full SU(3) symmetry of the model. By looking at the commonly used probes for thermalization (spectral statistics, distribution of local observables and scaling of entanglement entropy), we show that the model exhibits a non-ergodic regime over a broad range of system sizes for strong enough disorder, contrasting with the rapid thermalization observed at weak disorder

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Gérôme, Paul. "Taxinomie et mythanalyse des techniques du corps contemporaines". Lille 3 : ANRT, 1989. http://catalogue.bnf.fr/ark:/12148/cb37619397s.

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Libri sul tema "Techniques à N corps"

Dharma-Wardana, M. W. C. Le problème à N corps. [Paris: Association pour la diffusion de la connaissance scientifique, 1986.

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Newton, Paul K. The N-Vortex Problem: Analytical Techniques. New York, NY: Springer New York, 2001.

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Martin, Philippe A. Problèmes à N-corps et champs quantiques: Cours élémentaire. Lausanne: Presses polytechniques et universitaires romandes, 1990.

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Martin, Philippe A. Problèmes à N-corps et champs quantiques: Cours élémentaire. Freiburg: Presses polytechniques et universitaires romandes, 1990.

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Université des sciences humaines de Strasbourg, a cura di. L'espace des sciences et techniques des activités physiques et sportives: Recours au corps et effets de corps. Lille: A.N.R.T. Université de Lille III, 1993.

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Mahrazi, Mohand. Dictionnaire des expressions Kabyles liées au corps humain: Symbolique et représentations = Asegzawal n tenfaliyin n teqbaylit yerzan tafekka n umdan : tizumla d tgensas. [Algeria?]: Editions Elamel, 2017.

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VII, Université de Paris, a cura di. Au seuil de la figurabilité: De l'usage psychothérapeutique des techniques du corps. Lille: A.N.R.T. Université de Lille III, 1990.

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Fauché, Serge. Techniques du corps et traitements de l'esprit aux XVIIIè et XIXè sièckes. Paris: Harmattan, 1997.

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United States. Department of the Army. Static line parachuting techniques and training. Washington, DC: Headquarters, Dept. of the Army, 1996.

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Corps, United States Marine. Tactics, techniques, and procedures for field artillery target acquisition. Washington, D.C.]: U.S. Marine Corps, 2002.

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Capitoli di libri sul tema "Techniques à N corps"

Bundy, Alan. "N". In Catalogue of Artificial Intelligence Techniques, 100–106. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-97276-8_14.

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Meyer, Kenneth R., e Daniel C. Offin. "Variational Techniques". In Introduction to Hamiltonian Dynamical Systems and the N-Body Problem, 345–72. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-53691-0_13.

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Meyer, Kenneth, Glen Hall e Dan Offin. "Variational Techniques". In Introduction to Hamiltonian Dynamical Systems and the N-Body Problem, 301–27. New York, NY: Springer New York, 2009. http://dx.doi.org/10.1007/978-0-387-09724-4_12.

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Holt, Ron, Jerry Mayers e Andrew Taylor. "Neutron Experimental Techniques for n(p)". In Momentum Distributions, 295–305. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4899-2554-1_21.

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Steinbach, Bernd, e Christian Posthoff. "Derivative Operations for Classes C N $$\mathcal {C}_N$$ of Boolean Functions". In Advanced Boolean Techniques, 51–82. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-20323-8_3.

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Messina, Angela, Donata Agata Romeo, Rita Barone, Luisa Sturiale, Angelo Palmigiano, Mario Zappia e Domenico Garozzo. "CSF N-Glycomics Using MALDI MS Techniques". In Biomarkers for Alzheimer’s Disease Drug Development, 49–65. New York, NY: Springer US, 2024. http://dx.doi.org/10.1007/978-1-0716-3774-6_4.

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Cantale, C., M. Casarci, A. De Stefanis, G. M. Gasparini, L. Nardi e A. Salluzzo. "N,N Dialkylaliphatic Amides as Extractant of Platinum Group Metals". In New Separation Chemistry Techniques for Radioactive Waste and Other Specific Applications, 57–63. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3654-9_10.

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Eguchi, Tohru. "Topological σ-Models and the Large-N Techniques". In Low-Dimensional Applications of Quantum Field Theory, 121–43. Boston, MA: Springer US, 1997. http://dx.doi.org/10.1007/978-1-4899-1919-9_6.

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Vijayabalaji, S., S. Sivaramakrishnan e P. Balaji. "Cubic n-Inner Product Space". In Soft Computing Techniques in Engineering, Health, Mathematical and Social Sciences, 121–36. Boca Raton: CRC Press, 2021. http://dx.doi.org/10.1201/9781003161707-8.

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Al-Begain, Khalid, Alexander Dudin e Valentina Klimenok. "Queueing System MAP/PH/N with Propagated Failures". In Analytical and Stochastic Modeling Techniques and Applications, 14–28. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-13568-2_2.

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Atti di convegni sul tema "Techniques à N corps"

Yadav, Renu, M. Mohammed Kasim, S. Srividhya, Yogendra Kumar, T. Mohanraj e S. P. V. Subba Rao. "The Techniques used for Sustainable Communication System FR 6-G type of N/W". In 2024 4th International Conference on Advance Computing and Innovative Technologies in Engineering (ICACITE), 79–84. IEEE, 2024. http://dx.doi.org/10.1109/icacite60783.2024.10616452.

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Ghanizadeh, Amin, Chengyao Song, Jaime Cesar e Chunqing Jiang. "Evaluation of Produced Hydrocarbons Composition During Cyclic CO2 Injection (Huff-N-Puff) in Artificially-Fractured Shale Core Sample". In SPE Canadian Energy Technology Conference and Exhibition. SPE, 2023. http://dx.doi.org/10.2118/212720-ms.

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Abstract Natural and hydraulic fractures are important contributors to production performance of low-permeability (‘tight’) hydrocarbon reservoirs during primary and enhanced oil recovery. Laboratory studies that have investigated core-scale huff-n-puff (HNP) processes in ‘fractured’ cores are rare, and focused on ‘rock’ analysis primarily, as opposed to ‘fluid’ analysis. The objective of this proof-of-concept experimental study is to evaluate the application of a new core-scale HNP technique, ‘flow-through-frac’, for tracking compositional evolution of produced liquid hydrocarbons during cyclic gas (CO2 herein) injection in ‘fractured’ low-permeability oil reservoirs. The flow-through-frac technique reproduces the near-fracture conditions during a typical HNP process, with significantly faster testing times (25-50%) compared to conventional techniques (e.g., flow-around). The experimental procedure includes: 1) artificially fracturing core plug sample under differential stress to simulate an induced fracture, 2) saturating the fractured core with de-waxed in-situ (formation) oil, and 3) implementing multiple cycles of gas (e.g., CO2, produced gas) injection, soaking and production. To determine whether this technique can detect compositional variations despite its short duration, the compositions of the original in-situ (dead) oil and produced liquid hydrocarbon sample were compared after a typical core-scale HNP process (4 cycles) using CO2. A low-porosity (3.3%), low-permeability (1.25·10−4 md) Duvernay shale (western Canada) core plug sample was analyzed in this study. Compared to the in-situ (dead) oil, lighter components (C7-C11) were significantly (up to an order of magnitude) leaner in the oil sample produced after 4 cycles of CO2 HNP (fractured core plug). The lighter the hydrocarbon components, the leaner the concentrations in the produced oil. The intermediate components (C12-C28) were enriched in the produced oil, with larger discrepancies for C14-C22 components. The latter observation is attributed to the replacement of adsorbed C17-C19 components by injected CO2, in agreement with recent molecular simulation and experimental studies. The concentrations of heavier components (C29-C33) were similar between the in-situ and produced oil samples. Through combining core-scale CO2 HNP and fluid sampling/testing, this work demonstrates that the flow-through-fracture method can detect compositional variations during a typical core-scale HNP experiment. This technique can enable operators to track the composition of produced hydrocarbons at near-fracture conditions at a significantly shorter time frame (25–50%) than the existing methods. This integrated rock and fluid experimental program could potentially become valuable to not only core-based evaluation of enhanced oil recovery (EOR) in unconventional oil reservoirs but also potentially coupled CO2/produced gas EOR and sequestration processes in fractured shale reservoirs.

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Nazari Moghaddam, Rasoul, Marcel Van Doorn, Hans Oskarsson e Paul Ferm. "New Diversion Fluid for Chelate-Based Acid Systems". In SPE International Conference on Oilfield Chemistry. SPE, 2023. http://dx.doi.org/10.2118/213832-ms.

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Abstract Chelating agents have been used in the upstream oil and gas industry as a scale remover, iron control agent and acidizing fluid. Despite several studies on diversion techniques for conventional acid systems (i.e., HCl or organic acid), the application of diverting systems has rarely been studied during acidizing jobs using chelating agents. In this study, a new diverting system is introduced and experimentally evaluated during the stimulation of carbonate cores by a chelate-based acid. The diverting system introduced in this study is a unique blend of viscoelastic surfactants based on sulfobataine and amine oxide chemistries. The new diverting system was examined during carbonate acidizing by Glutamic acid N, N-diacetic acid (GLDA). The diverting system, which is specially designed for high temperature applications, was used during dual coreflooding experiments at 130°C. In these evaluations, Indiana limestone cores with various permeability contrasts were used. The pressure behavior, permeability improvement/reduction, and the production flow rates from each core plug were measured. Finally, to visualize the wormhole propagation inside each core, CT scanning was conducted after the treatments. From the results, it was found that the diverting system can block the formation for a certain period of time (<2 hours). During this period, the diverting system shows the highest viscosity and can temporarily block the high permeability cores (>100 mD) which diverts the injected acid to the lower permeability core. It was found that the acid diversion lasts for a longer time when the system has a higher permeability contrast. From the CT-scan images, it was found that the wormholes were propagated up to 50% across the low permeability core when 0.3 PV of the diversion fluid was injected. With enough volume of the diversion fluid, the acid system was fully diverted, and the treatment fluid achieved full-length wormholes in both high permeability (HP) and low permeability (LP) cores. It was also shown that required volume of the diverting fluid is a function of permeability contrast. It was demonstrated this pre-flush diversion technique can be successfully applied and it needs less VES volume compared to the continuous VES injection with acid. The novel formulation introduced in this study is a cost-effective solution specially designed for the chelate-based acid systems. The proposed formulation can also be optimized to resolve diversion challenges in other applications at high temperature.

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Mohammed, Tariq, Amin Ghanizadeh, Christopher R. Clarkson e Zhengru Yang. "Profile Ultrasonic Velocity Measurements Performed on Slabbed Core: Implications for High-Resolution Permeability Prediction in Low-Permeability Rocks". In SPE Canadian Energy Technology Conference. SPE, 2022. http://dx.doi.org/10.2118/208901-ms.

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Abstract Calibration of reservoir models for unconventional hydrocarbon reservoirs requires permeability data as input. Accurate permeability prediction from velocity data is desirable due to the relative abundance of velocity data that is typically available during exploration and development programs (e.g., through seismic imaging and well logging). Therefore, the development of fast and inexpensive ‘screening’ techniques tha can provide reliable estimation of permeability at high-resolution (cm-scale) using velocity data could be valuable to exploration/development programs in unconventional reservoirs. A new experimental apparatus is described herein for measuring ultrasonic velocities (P- and S-wave) along the length of slabbed cores of low-permeability rocks at high-resolution (cm-scale). A statistical approach that combines along-core (profile) ultrasonic velocity testing and non-destructive experimental techniques (X-ray fluorescence, mechanical hardness, and profile permeability) is employed to develop predictive models for estimating permeability. Two slabbed cores from the Canadian Montney and Bakken formations, covering multiple geological intervals (tight siltstones/sandstones units), were analyzed for validation purposes. Reasonable agreement is found between log- and lab-derived (ultra)sonic velocity data, indicating similar trends with depth. However, the exact log- and lab-derived (ultra)sonic velocity values are different due to the differences in stress conditions between the field and laboratory measurements and the direction of wave travel. A maximum variation of ±20 m/s is observed for both P- and S-wave velocities when measurements were repeated on the same points, providing evidence of experimental repeatability and reproducibility. Relationships exist between laboratory-measured profile ultrasonic velocities (S-wave), profile permeability, mechanical hardness, and clay content (inferred from elemental composition data). The profile S-wave velocities decrease with increasing permeability (R2 = 0.6, n = 230). Advanced statistical methods (e.g., genetic algorithms) are employed to improve the velocity-permeability relationship and develop models for indirect estimation of permeability from S-wave velocities. The performance of these models is dependent upon lithology and rock fabric (e.g., silt vs. sand, degree of cementation), with a better correlation achieved for intervals with lower porosity and permeability (<±15% maximum discrepancy between measured and predicted permeability values; R2 = 0.78, n = 230). This study introduces a new experimental apparatus, and a practical ‘screening’ workflow, that can be used for permeability prediction using S-wave velocities collected on slabbed cores. This predictive model can be used to estimate permeability below the lower limit (0.001 md) of pressure-decay profile permeability measurements. The findings are beneficial to operators developing tight siltstone/sandstone resources by allowing them to characterize permeability in low-permeability (<0.001 md) intervals for applications such as optimizing stimulation design and subsurface fluid injection.

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Barda, Jeff. "Le corps en lecture publique : techniques et « re-physication de la pensée »". In Écrivains en performances. Fabula, 2019. http://dx.doi.org/10.58282/colloques.6404.

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Polli, Andrea, e Joe Gilmore. "N." In SIGGRAPH07: Special Interest Group on Computer Graphics and Interactive Techniques Conference. New York, NY, USA: ACM, 2007. http://dx.doi.org/10.1145/1280120.1280199.

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Elkhatib, O., M. Abdallah, H. Elnaggar, A. S. Hanamertani, E. Al-Shalabi e S. Ahmed. "Huff-N-Puff Foam Injection in Naturally Fractured Carbonates Using Supercritical CO2". In SPE Improved Oil Recovery Conference. SPE, 2024. http://dx.doi.org/10.2118/218154-ms.

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Abstract Foam injection into naturally fractured reservoirs unequivocally has superior merits over pure gas injection. In this study, we present a novel foam generation strategy that incorporates the co-injection of surfactant and supercritical CO2 with huff-n-puff technique for the efficient diversion of the foaming gas into the rock matrix of fractured carbonates. A series of high pressure and temperature experiments were performed in fractured Indiana limestone cores with different permeabilities. First, gas injection was attempted to displace the oil from the fracture followed by foam flooding through the co-injection of a zwitterionic surfactant as a foaming agent and supercritical CO2. Then, a soaking period commenced at 200 psi above the preset pore pressure. Another co-injection of the foaming agent and scCO2 was carried out thereafter. The effect of the soaking pressure was evaluated by further utilizing 500 psi above the preset pore pressure in a subsequent soaking cycle. Similarly, this step was followed by a final foam injection to evaluate the potential increase in oil recovery. The incremental recovery by foam injection over gas flooding, i.e., 21-24%, was attributed to the foam invasion into the permeable pathways in the rock matrix while the selective diversion of surfactant solution and the increase in foam strength were the responsible mechanisms for oil recovery from the low-permeability core. In the latter case, the gradual evolution of foam strength was corroborated by the rising pressure drop across the fractured core. Besides, the imbibing surfactant solution across the fracture surface behind the foam front drove the crude oil production along the path ahead of the foam front, aligning with the mechanism of countercurrent imbibition. Subsequent soaking of the foam into the fractured cores managed to provide enough pressure and time for the invading scCO2 to develop hydraulic conductivity throughout the rock matrix mobilizing and relocating crude oil from previously inaccessible and deep pores toward fracture-neighboring pores. Subsequent foam injection produced this mobilized oil inducing an incremental oil recovery of 6% and 17% from the high- and low-permeability cores, respectively. Higher soaking pressure yielded even more oil recovery highlighting the role played by the scCO2 phase pressure in overcoming the threshold capillary pressure of rock matrix in mobilizing their resident oil and brine phases. As a result, the proposed foam huff-n-puff technique has proven to produce significantly higher oil recoveries from both high and low permeable limestones. Besides, tighter rocks with lower permeability would have the greatest benefit from the proposed procedure which indicates its promising potential performance in unconventional and ultra-tight reservoirs.

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Salem, Abdel Rahman, Ibrahim Soliman e Ryoichi S. Amano. "Crossflow Minimization for Jet Impingement Cooling Applications". In ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gt2023-101162.

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Abstract Jet impingement is used to efficiently cool gas turbine blades and other engine components. However, jet-to-jet interactions result in the accumulation of crossflow as the spent air migrates downstream, which usually causes a decay in the Nusselt number and reduces the overall cooling performance. In this study, several crossflow mitigation techniques are investigated by attaching small and easy-to-manufactured crossflow diverters to protect jet cores from upstream crossflows and, therefore, enhance heat transfer performance. Three diverter shapes of cylindrical, rectangular, and ribbed type are studied within a 25-jet array under laminar and turbulent flow regimes (Rej of 2,500–10,000). Three-dimensional Navier-Stokes (N-S) equations are solved under the k-ɛ turbulence model following a mesh sensitivity study. Diverter heights of 25%, 50%, and 75%, as a percentage of jet-to-target spacing denoted as quarter-length (QL), half-length (HL), and three-quarter-length (TQL), respectively, are considered with a constant heat flux condition. Results show an increase in average Nusselt number values from 6.6% to 12% achieved by a TQL cylindrical-shaped diverter. However, the associated friction factor is also increased by 9.9%–24.3% on average compared to the baseline model. Nevertheless, the heat transfer performance parameter (η) is introduced to quantify the desired gain in Nu and the cost in the pressure loss. Consequently, results show a net enhancement of up to 5.2%, 3.1%, and 3.8% for cylindrical, rectangular, and ribbed-type diverters, respectively.

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Kun, Sergey Y. "Angular distributions in ¹⁸⁴W(n,n') ²⁰⁹Bi(n,n') inelastic scattering: forward peaking of evaporated neutrons?" In 4th International Conference on Applications of Nuclear Techniques: Neutrons and their Applications, a cura di George Vourvopoulos e Themis Paradellis. SPIE, 1995. http://dx.doi.org/10.1117/12.204142.

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Zarb-Adami, K., A. Faulkner, J. G. Bij de Vaate, G. W. Kant e P. Picard. "Beamforming techniques for large-N aperture arrays". In 2010 IEEE International Symposium on Phased Array Systems and Technology (ARRAY 2010). IEEE, 2010. http://dx.doi.org/10.1109/array.2010.5613258.

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Rapporti di organizzazioni sul tema "Techniques à N corps"

Haynes, F. D., Robert Haehnel, Charles Clark e Leonard Zabilansky. Ice Control Techniques for Corps Projects. Fort Belvoir, VA: Defense Technical Information Center, settembre 1997. http://dx.doi.org/10.21236/ada329402.

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Haring, Christopher, Autumn Murray e Forrest Luna. Sustainable bank and channel stabilization techniques in arid southwest streams. Engineer Research and Development Center (U.S.), agosto 2023. http://dx.doi.org/10.21079/11681/47380.

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Channel stabilization and enhancement approaches take many different forms and are implemented using varying construction methods, materials, and techniques. The purpose of this study is to provide a comprehensive evaluation of sustainable streambank stabilization measures that are typically applied in arid southwest (SW) streams. This study was conducted at the request of the US Army Corps of Engineers (USACE), Albuquerque District (SPA), and USACE Headquarters. The document also provides rationale for evaluating bank and bed stabilization measures.

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Poy, F. L. Fouling effects of tri-n-butylphosphate on reverse osmosis performance and techniques for performance recovery. Office of Scientific and Technical Information (OSTI), luglio 1987. http://dx.doi.org/10.2172/6173330.

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Alchanatis, Victor, Stephen W. Searcy, Moshe Meron, W. Lee, G. Y. Li e A. Ben Porath. Prediction of Nitrogen Stress Using Reflectance Techniques. United States Department of Agriculture, novembre 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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Baekey,, Kyle, Michael Hanowsky, Thomas Less, W. Lillycrop, Peter Stynoski, Matthew Smith, Patrick Plews, Andrew Loff e Christina Parr. Composite material applications and research roadmap for US Army Corps of Engineers Civil Works. Engineer Research and Development Center (U.S.), luglio 2024. http://dx.doi.org/10.21079/11681/48755.

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This report discusses and ranks the remaining research, development, and deployment opportunities for fiber-reinforced polymer composite materials in USACE marine infrastructure applications. Following the successes of at least 10 fiber-reinforced polymer composite pilot projects from 2015 to 2022, Public Law 117-58, the Infrastructure Investment and Jobs Act, allocated funding for a roadmap report that articulates lingering implementation barriers and prioritizes steps to overcome those challenges through laboratory and field experimentation. The objective analysis herein draws from real Operational Condition Assessment data generated in the field. Key opportunities lie in inspection techniques, standardized design approaches for molded components, and improved guidance to ad-dress abrasion, fatigue, and concentrated load cases at the 10-meter scale.

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Bell-Gray, L. A. A Study of Computational Techniques Related to Prediction of Centroids of Dosage Beyond Measured Time Tn Where n is Known. Fort Belvoir, VA: Defense Technical Information Center, maggio 1985. http://dx.doi.org/10.21236/ada157406.

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Herath Mudiyanselage, Dinusha. Design and optimization of edge termination techniques for β-Ga2O3/GaN heterojunction for p-n power diodes using TCAD simulation. Ames (Iowa): Iowa State University, dicembre 2021. http://dx.doi.org/10.31274/cc-20240624-502.

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Younes, W., J. A. Becker, L. A. Bernstein, P. E. Garret, C. A. McGrath, D. P. McNabb, R. O. Nelson, M. Devlin, N. Fotiades e G. D. Johns. The 235U(n,2n(gamma)) Yrast Partial Gamma-Ray Cross Sections: A Report on the 1998 -- 1999 GEANIE Data and Analysis Techniques. Office of Scientific and Technical Information (OSTI), settembre 2000. http://dx.doi.org/10.2172/15013508.

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Younes, W., J. A. Becker, L. A. Bernstein, P. E. Garrett, C. A. McGrath, D. P. McNabb, R. O. Nelson, M. Devlin, N. Fotiades e G. D. Johns. The 235U(n,2n(gamma)) Yrast Partial Gamma-Ray Cross Sections: A Report on the 1998 -- 1999 GEANIE Data and Analysis Techniques Appendix. Office of Scientific and Technical Information (OSTI), settembre 2000. http://dx.doi.org/10.2172/15013509.

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Pawlak, Robert J., e Ron A. Stapleton. Nonparametric Multisensor Track Initiation Method for Nonuniform Nonstationary Environments Part II: A Comparison of M/N and ANMSTI Track Initiation Techniques Applied to the Wallops Island Multisensor Integration Experiment. Fort Belvoir, VA: Defense Technical Information Center, luglio 1995. http://dx.doi.org/10.21236/ada309319.

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