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Статті в журналах з теми "Onde surface gravite"
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BRONNIKOV, KIRILL A., and ALEXEI A. STAROBINSKY. "ONCE AGAIN ON THIN-SHELL WORMHOLES IN SCALAR–TENSOR GRAVITY." Modern Physics Letters A 24, no. 20 (June 28, 2009): 1559–64. http://dx.doi.org/10.1142/s0217732309030928.
Повний текст джерелаАнотація:
It is proved that all thin-shell wormholes built from two identical regions of vacuum static, spherically symmetric spacetimes have a negative shell surface energy density in any scalar–tensor theory of gravity with a non-ghost massless scalar field and a non-ghost graviton.
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MORDANE, Soumia, Kamal L. MAROIHI, Abdellatif ORBI, and Mohamed CHAGDALI. "Une formulation parabolique pour la propagation en profondeur finie des ondes de gravité en surface." Oceanologica Acta 24, no. 3 (May 2001): 287–94. http://dx.doi.org/10.1016/s0399-1784(01)01147-1.
Повний текст джерела
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Longuet-Higgins, M. S. "The propagation of short surface waves on longer gravity waves." Journal of Fluid Mechanics 177 (April 1987): 293–306. http://dx.doi.org/10.1017/s002211208700096x.
Повний текст джерелаАнотація:
To understand the imaging of the sea surface by radar, it is useful to know the theoretical variations in the wavelength and steepness of short gravity waves propagated over the surface of a train of longer gravity waves of finite amplitude. Such variations may be calculated once the orbital accelerations and surface velocities in the longer waves have been accurately determined – a non-trivial computational task.The results show that the linearized theory used previously for the longer waves is generally inadequate. The fully nonlinear theory used here indicates that for longer waves having a steepness parameter AK = 0.4, for example, the short-wave steepness can be increased at the crests of the longer waves by a factor of order 8, compared with its value at the mean level. (Linear theory gives a factor less than 2.)The calculations so far reported are for free, irrotational gravity waves travelling in the same or directly opposite sense to the longer waves. However, the method of calculation could be extended without essential difficulty so as to include effects of surface tension, energy dissipation due to short-wave breaking, surface wind-drift currents, and to arbitrary angles of wave propagation.
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Bechtel, S. E. "The Oscillation of Slender Elliptical Inviscid and Newtonian Jets: Effects of Surface Tension, Inertia, Viscosity, and Gravity." Journal of Applied Mechanics 56, no. 4 (December 1, 1989): 968–74. http://dx.doi.org/10.1115/1.3176198.
Повний текст джерелаАнотація:
The motion of inviscid and Newtonian jets issuing from elliptical orifices is analyzed. The analysis is not confined to small departures of the jet free surface from a circular cylindrical mean surface, but rather is fully nonlinear. Two types of behavior are predicted: (1) In the presence of surface tension the major axis of the elliptical jet cross-section alternates between perpendicular directions with distance down the jet. In this case the system is described as a single-degree-of-freedom nonlinear oscillator, conservative for the inviscid elliptical jet in the absence of gravity, and nonconservative for the Newtonian jet. (2) When surface tension is neglected, the transformation occurs only once, after which the jet flattens into a sheet perpendicular to the major axis of the orifice. The effect of gravity is discussed both for downward flowing jets and fountains.
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Benilov, E. S. "Oblique liquid curtains with a large Froude number." Journal of Fluid Mechanics 861 (December 19, 2018): 328–48. http://dx.doi.org/10.1017/jfm.2018.925.
Повний текст джерелаАнотація:
This paper examines two-dimensional liquid curtains ejected at an angle to the horizontal and affected by gravity and surface tension. The flow in the curtain is, generally, sheared. The Froude number based on the injection velocity and the outlet’s width is assumed large; as a result, the streamwise scale of the curtain exceeds its thickness. A set of asymptotic equations for such (slender) curtains is derived and its steady solutions are examined. It is shown that, if the surface tension exceeds a certain threshold, the curtain – quite paradoxically – bends upwards, i.e. against gravity. Once the flow reaches the height where its initial supply of kinetic energy can take it, the curtain presumably breaks up and splashes down.
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Mouyen, Maxime, Philippe Steer, Kuo-Jen Chang, Nicolas Le Moigne, Cheinway Hwang, Wen-Chi Hsieh, Louise Jeandet, et al. "Quantifying sediment mass redistribution from joint time-lapse gravimetry and photogrammetry surveys." Earth Surface Dynamics 8, no. 2 (June 22, 2020): 555–77. http://dx.doi.org/10.5194/esurf-8-555-2020.
Повний текст джерелаАнотація:
Abstract. The accurate quantification of sediment mass redistribution is central to the study of surface processes, yet it remains a challenging task. Here we test a new combination of terrestrial gravity and drone photogrammetry methods to quantify sediment mass redistribution over a 1 km2 area. Gravity and photogrammetry are complementary methods. Indeed, gravity changes are sensitive to mass changes and to their location. Thus, by using photogrammetry data to constrain this location, the sediment mass can be properly estimated from the gravity data. We carried out three joint gravimetry–photogrammetry surveys, once a year in 2015, 2016 and 2017, over a 1 km2 area in southern Taiwan, featuring both a wide meander of the Laonong River and a slow landslide. We first removed the gravity changes from non-sediment effects, such as tides, groundwater, surface displacements and air pressure variations. Then, we inverted the density of the sediment with an attempt to distinguish the density of the landslide from the density of the river sediments. We eventually estimate an average loss of 3.7 ± 0.4 × 109 kg of sediment from 2015 to 2017 mostly due to the slow landslide. Although the gravity devices used in this study are expensive and need week-long surveys, new instrumentation currently being developed will enable dense and continuous measurements at lower cost, making the method that has been developed and tested in this study well-suited for the estimation of erosion, sediment transfer and deposition in landscapes.
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Konoplya, R. A., and A. Zhidenko. "How general is the strong cosmic censorship bound for quasinormal modes?" Journal of Cosmology and Astroparticle Physics 2022, no. 11 (November 1, 2022): 028. http://dx.doi.org/10.1088/1475-7516/2022/11/028.
Повний текст джерелаАнотація:
Abstract Hod's proposal claims that the least damped quasinormal mode of a black hole must have the imaginary part smaller than half of the surface gravity at the event horizon. The Strong Cosmic Censorship in General Relativity implies that this bound must be even weaker: half of the surface gravity at the Cauchy horizon. The appealing question is whether these bounds are limited by the Einstein theory only? Here we will present numerical evidence that once the black hole size is much smaller than then the radius of the cosmological horizon, both the Hod's proposal and the strong cosmic censorship bound for quasinormal modes are satisfied for general spherically symmetric black holes in an arbitrary metric theory of gravity. The low-lying quasinormal frequencies have the universal behavior in this regime and do not depend on the near-horizon geometry, but only on the asymptotic parameters: the value of the cosmological constant and black hole mass.
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Garstang, Michael, Steven Greco, George D. Emmitt, Tricia A. Miller, and Michael Lanzone. "An Instrumented Golden Eagle’s (Aquila chrysaetos) Long-Distance Flight Behavior." Animals 12, no. 11 (June 6, 2022): 1470. http://dx.doi.org/10.3390/ani12111470.
Повний текст джерелаАнотація:
One-second-processed three-dimensional position observations transmitted from an instrumented golden eagle were used to determine the detailed long-range flight behavior of the bird. Once elevated from the surface, the eagle systematically used atmospheric gravity waves, first to gain altitude, and then, in multiple sequential glides, to cover over 100 km with a minimum expenditure of its metabolic energy.
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Welker, William V., and Donald L. Peterson. "A Surface-Roller Herbicide Applicator for Weed Control in Turf." Weed Technology 3, no. 3 (September 1989): 472–74. http://dx.doi.org/10.1017/s0890037x00032590.
Повний текст джерелаАнотація:
A surface-roller wiper that rotates by direct contact with the ground was developed to apply herbicides to broadleaf weeds in turf. The free-wheeling roller 1.8 m wide consists of a 30-cm diam PVC pipe covered with a 1.3-cm thick carpet The herbicide is delivered by gravity to the carpet through a pipe manifold. Broadleaf weeds in turf were effectively controlled with 2,4-D roller applied once as a2%solution (2.2 kg ae/ha) or twice as a 1% solution (1.1 kg/ha). Herbicide drift was avoided with the roller applicator as indicated by lack of injury to tomato plants downwind from 2,4-D roller applied as a5%(5.6 kg/ha) solution.
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TJAN, K. K., and W. R. C. PHILLIPS. "On impulsively generated inviscid axisymmetric surface jets, waves and drops." Journal of Fluid Mechanics 576 (March 28, 2007): 377–403. http://dx.doi.org/10.1017/s0022112007004648.
Повний текст джерелаАнотація:
The evolution of an unbounded inviscid free surface subjected to a velocity potential of Gaussian form and also to the influence of inertial, interfacial and gravitational forces is considered. This construct was motivated by the occurrence of lung haemorrhage resulting from ultrasonic imaging and pursues the notion that bursts of ultrasound act to expel droplets that puncture the soft air-filled sacs in the lung plural surface, allowing them to fill with blood. The tissue adjacent to the sacs is modelled as a liquid and the air–tissue interface in the sacs as a free surface. The evolution of the free surface is described by a boundary-integral formulation and, since the free surface evolves slowly relative to the bursts of ultrasound, they are realized as an impulse at the free surface, represented by the velocity potential. As the free surface evolves, it is seen to form axisymmetric surface jets, waves or droplets, depending upon the levels of gravity and surface tension. Moreover the droplets may be spherical and ejected away from the surface or an inverted tear shape and fall back to the surface. These conclusions are expressed in a phase diagram of inverse Froude number Fr−1 versus inverse Weber number We−1. Specifically, while axisymmetric surface jets form in the absence of surface tension and gravity, gravity acts to bound their height, rendering them waves, although instability overrides the calculation prior to its reaching that bound. Surface tension acts to suppress the instability (provided that We−1 > 0.045) and to form drops; if sufficiently strong it can also damp the evolving wave, causing it to collapse. The pinchoff which effects spherical drops is of power-law type with exponent 2/3, and the universal constant that relates the necking radius to the time from pinchoff, thereby realizing a finite-time singularity, has the value ${\mathfrak{K}} \,{=}\, 0.45 \pm 0.025$. Finally, drops can occur once the mechanical index, a dimensional measure used in ultrasonography, exceeds 0.5.
Дисертації з теми "Onde surface gravite"
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Guibourg, Sandrine. "MModélisations numérique et expérimentale des houles bidimensionnelles en zone cotière." Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10160.
Повний текст джерелаАнотація:
Une analyse theorique detaillee des equations de boussinesq et de serre a ete realisee. Les domaines de validite de chaque equation ont ete determines theoriquement. Ces equations d'ondes longues sont discretisees selon un schema aux differences finies pour des ondes de surface libre sur fond plat et fond variable. Par le biais d'une comparaison numerique avec des essais experimentaux d'ondes longues sur fond plat, les modeles numeriques ont ete etendus a la description des ondes courtes. Un terme dispersif correctif a ete introduit pour ameliorer les capacites dispersives des modeles. Des essais numeriques de propagation d'ondes longues sur un talus ont egalement ete compares aux experiences. Une etude de l'interaction d'une houle courte de haute frequence avec une onde solitaire nous a conduit a mesurer le dephasage que subit l'onde courte apres le passage du soliton. Nous nous sommes consacres a la validation experimentale d'une comparaison entre les modeles de boussinesq et de serre sur des plages peu inclinees, ainsi qu'a l'evolution du nombre d'ursell le long de la plage. L'etude experimentale a ensuite ete etendue aux phenomenes de run up, de run down et aux calculs des coefficients de reflexion des plages etudiees. Pour calculer numeriquement les run up, nous avons ameliore le modele de serre par des conditions de trait de cote variable
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Chapalain, Georges. "Étude hydrodynamique et sédimentaire des environnements littoraux dominés par la houle." Université Joseph Fourier (Grenoble ; 1971-2015), 1988. http://www.theses.fr/1988GRE10121.
Повний текст джерелаАнотація:
La propagation des houles longues est étudiée expérimentalement, théoriquement et numériquement. La validité du modèle harmonique quasi-résonnant de lau et barcilon (1972) est confirmée. Les processus hydro-sédimentaires se développant dans la couche limite turbulente de fond générée par la houle sont analysés à l'aide d'un modèle uni-dimensionnel avec fermeture turbulente au second ordre. Un modèle simplifie avec fermeture turbulente au premier ordre est envisagé dans la perspective d'une modélisation des interactions des trains de houle avec un fond sableux. La modélisation hydro-morphologique ainsi élaborée explique la formation des barres sableuses d'avant-cote. Elle est confrontée avec succès à des mesures effectuées dans le lac Huron et dans le golfe du Saint-Laurent. L'extension de la modélisation a des substrats de granulométrie étendue est réalisée en vue de la simulation du tri granulométrique observe sur les systèmes de barres littorales. Enfin, un essai d'intégration des pertes d'énergie par les déferlements multiples survenant sur les séquences de barres est entrepris.
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Barros, Ricardo. "Gravity waves in two-layer flows with free surface." Aix-Marseille 3, 2007. http://www.theses.fr/2007AIX30080.
Повний текст джерелаАнотація:
Nous étudions dans cette thèse la propagation des ondes dans un écoulement à deux couches et à surface libre. Deux classes de modèles sont considérées. Nous nous consacrons d'abord à la version à deux-couches du modèle de Saint-Venant. Ce modèle est strictement hyperbolique pour des faibles vitesses relatives. Il serait naturel de considérer ce système d'équations pour la description des sauts hydrauliques. Il s'avère que, comme pour la plupart des modèles décrivant des systèmes multi-vitesses, les équations ne sont pas présentées sous forme conservative. C'est pourquoi on a réalisé une étude sur le nombre de lois de conservation pour le système qui semble indiquer que celui-ci est en fait non-conservatif. Comme conséquence, on a l'impossibilité de présenter un ensemble complet de conditions de Rankine-Hugoniot permettant ainsi la caractérisation des solutions faibles dans le sens classique. Nous obtenons ensuite un modèle dispersif adapté à la description de la propagation des ondes de grande amplitude pour le même système physique. Ce modèle est une généralisation naturelle du modèle de Green-Naghdi et sa dérivation est basée sur le principe d'Hamilton. L'idée conduisant au résultat consiste en l'obtention d'un Lagrangien pour le modèle approché en introduisant directement les approximations dans le Lagrangien du modèle complet. Par conséquent, la structure variationnelle ainsi que les propriétés de symétrie correspondantes sont préservées. De plus, aucune restriction du type ondes de faible amplitude ou écoulement potentiel n'est ici considéré. Comme dans le cas des équations d'Euler complètes, ce modèle reproduit la résonance entre les ondes courtes et les ondes longues. Dans ce cadre on montre, par des calculs numériques, l'existence de trajectoires homoclines qui correspondent aux vraies ondes solitaires ayant les mêmes vitesses à l'infini dans chaque couche. L'étude de ces ondes se réduit à l'étude d'un système Hamiltonien à deux degrés de liberté. Les ondes progressives dépendent de trois paramètres: le rapport de densité des fluides, le rapport des épaisseurs de chaque couche et le nombre de Froude. Deux régimes caractérisés par l'élévation ou la dépression de l'interface entre deux couches sont présentés. Le rapport critique des épaisseurs des couches sépare ces deux régimes et il sera montré comment le relier aux changements de la structure pour le potentiel du système Hamiltonien. L'analyse du nombre et la nature des points d'équilibre se sont montrés décisives pour établir le résultat. On a constaté que leur nombre ne peut être que de quatre ou de deux, selon la vitesse de ces ondes (pour un rapport de densité des fluides et un rapport des épaisseurs fixés). Pour les paramètres qui correspondent aux conditions océaniques, on a observé l'existence des ondes solitaires et leur élargissement ("broadening") lorsque la vitesse de ces ondes tend vers une certaine valeur limite. Enfin nous considérons différents paramètres pour lesquelles des solutions avec plusieurs bosses ( "multi-humped shaped profile") existent, illustrant la richesse et la complexité du système considéréIn this work we study the wave propagation in two-layer flows with free surface. Two distinct classes of models are contemplated. First, we consider the "two-layer" version of the shallow water equations (also known by Saint-Venant's equations). This model is strictly hyperbolic for small relative velocities. It would be natural to consider this model as suitable for the description of hydraulic jumps. However, like most of models describing multi-velocity flows, the system is not presented in conservative form. We present a survey on the number of conservation laws available for the multi-dimensional case that seems to imply that the system is truly nonconservative. Therefore, the impossibility of presenting a complete set of Rankine-Hugoniot conditions enabling the characterization of weak solutions in the classical way. Then, we obtain a dispersive model suited to the description of large amplitude waves propagating in the same physical system. The model is a "two-layer" generalization of the Green-Naghdi model and can be derived by applying Hamilton's principle to a Lagrangian that results from the insertion of approximations directly into the Lagrangian for the full waterwave problem. As a consequence, the variational structure of the original problem and the corresponding symmetry properties are preserved. In addition, it is a fully nonlinear model and deals with rotational flows. As in the case of the full problem, the present model captures the resonance between short waves and long waves. In this framework it is shown, by using numerical computations, the existence of homoclinic trajectories embedded into the continuous spectrum. These correspond to true solitary waves having the same velocities at infinity in each layer. Their study reduces to the analysis of a Hamiltonian system with two degrees of freedom. The traveling-wave solutions depend on three parameters : the density ratio, the depth ratio and the Froude number based on the bottom layer. Two wave regimes, characterized by the elevation or depression of the interface between the layers are presented. A critical depth ratio separates these two regimes and it will be shown how it relates to a change of the structure of the potential for the Hamiltonian system. The analysis of the number and nature of critical points turned out to be decisive in this work. It was found that the number of critical points can be four or two, depending on the value of the Froude number (for fixed density and depth ratios). For sets of parameters corresponding to oceanic conditions we have perceived the existence of true solitary waves and their broadening whenever the wave speed increases towards a limit value. Finally, other sets of parameters are considered for which multi-humped solitons exist, highlighting the richness and complexity of the system considered
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Ioulalen, Mansour. "Etude de la stabilité linéaire d'ondes de gravité progressives et tridimensionnelles en profondeur infinie." Aix-Marseille 2, 1990. http://www.theses.fr/1990AIX22065.
Повний текст джерелаАнотація:
On s'interesse a l'etude de la stabilite lineaire d'ondes de surface de gravite tridimensionnelles en profondeur infinie. Pour cela une methode spectrale de type galerkin a ete developpee. Les equations du mouvement sont ramenees a un probleme aux valeurs propres generalise ou les perturbations sont decomposees spectralement en modes normaux. Le calcul de l'onde de base a ete etendu analytiquement jusqu'aux quatrieme et cinquieme ordres grace a l'utilisation d'un algorithme de calcul formel: reduce. Le recours a la methode ro a permis de retrouver a partir de solutions calculees semi-numeriquement jusqu'a l'ordre 27 les resonances harmoniques existant au sein d'un train d'ondes tridimensionnelles. L'etude de la stabilite lineaire de ces formes a montre que les instabilites de type modulationnelles ont des echelles de temps caracteristique beaucoup plus petites que celles correspondant aux resonances harmoniques. Pour des cambrures moderees de l'onde de base, les instabilites dominantes appartiennent a la classe i et peuvent conduire a des transitions sous-harmoniques. Les resonances harmoniques sont des instabilites de la classe i et conduisent a des bifurcations de l'onde de base. Aux fortes cambrures l'existence de bifurcations sous-harmoniques de la classe ii a ete mise en evidence
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Aubourg, Quentin. "Étude expérimentale de la turbulence d’ondes à la surface d’un fluide. La théorie de la turbulence faible à l’épreuve de la réalité pour les ondes de capillarité et gravité." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI061/document.
Повний текст джерелаАнотація:
La turbulence d’onde cherche à apporter une description statistique des interactions d’un ensemble d’ondes faiblement non-linéaires. Initiée dans les années 1960 par les travaux de Zakharov et de Hasselmann, cette théorie est régulièrement mise en défaut par les observations expérimentales, en particulier dans le régime d’ondes de gravité ainsi qu’aux abords de la transition gravito-capillaire. L’objectif de cette thèse est d’étudier expérimentalement ces deux régimes en analysant directement les interactions résonantes qui sont le cœur de la théorie de la turbulence faible. Une première expérience concerne le régime gravito-capillaire. Une cascade d’énergie constituée d’ondes faiblement linéaires est observée en accord avec la phénoménologie de la turbulence faible. L’utilisation d’outils statistiques d’ordre supérieur a permis de montrer que ce sont des interactions à 3-ondes essentiellement colinéaires qui gouvernent la cascade. La seconde expérience explore le régime gravitaire dans la plateforme de Coriolis. Le spectre de puissance montre la présence systématique d’une branche harmonique qui reste faible devant la composante linéaire. Les corrélations indiquent la présence d’interactions à 3-ondes entre la branche linéaire et la branche harmonique. Aucune interaction à 4-ondes comme le prévoit la théorie n’est observée. La dernière partie rapporte les résultats d’une expérience sur des ondes internes ainsi qu’une campagne de mesure in-situ de la mer Noire dont les données ont été mises à disposition par F. Ardhuin. Ces deux expériences confirment les résultats de la partie précédente et soulèvent la question de l’importance des interactions à 3-ondes avec la branche harmonique pour la génération de la cascade en régime de gravité…The wave turbulence provides a statistical description of the interactions of a large set of weakly non-linear waves. Introduced in the 1960s by the works of Zakharov and Hasselmann, this theory often fails against experiments, particularly for gravity waves and at the crossover for capillary-gravity waves. The objective of this PhD is to study experimentally these two regimes by looking directly at the resonant interactions that are the heart of the weak turbulence theory. The first experiment focuses on the capillary-gravity regime. An energy cascade composed of weakly linear waves is observed in agreement with the phenomenology of the theory. The use of higher order statistical tools shows that it is essentially 3-waves collinear interaction that govern the cascade. The second experiment explores the pure gravity regime thanks to the large dimensions of the Coriolis platform. The full energy spectrum shows the systematic presence of the harmonic branch, although it remains small compared to the linear component. The correlations indicate the presence of strong 3-waves interactions between the linear branch and the harmonics branches. No 4-waves interaction as assumed by the theory is observed. The last section reports the results from an experiment on internal waves and from in situ data of the Black Sea made available by F. Ardhuin. These two experiments confirm the results of the previous section and raise the question of the importance of the 3-wave interaction with the harmonic branch for generating the energy cascade in the gravity wave regime…
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Peureux, Charles. "Observation et modélisation des propriétés directionnelles des ondes de gravité courtes." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0091/document.
Повний текст джерелаАнотація:
Les vagues courtes sont omniprésentes à la surface des océans, avec des longueurs de quelques dizaines de mètres au mètre typiquement. Connaitre leurs directions de propagation en mer est important à plusieurs titres, notamment pour la compréhension de la dynamique de l'état de mer, des échanges air-mer ou de la dérive de particules en surface. Ces distributions directionnelles sont étudiées ici au regard des progrès récents réalisés en techniques d'instrumentation. L'analyse du bruit sismo-acoustique enregistré en grandes profondeurs permet d'extraire un comportement quasi-universel qui dépend indirectement de cette distribution à travers ladite intégrale de recouvrement. Il est cohérent avec des observations directes du champ de vagues obtenues à partir de reconstructions tridimensionnelles de la surface de l'océan. Alors que la direction de propagation des vagues longues s'aligne avec celle du vent, les vagues courtes s'en détachent d'autant plus à mesure que leurs échelles diminuent (bimodalité).La comparaison de ces observations avec les prédictions d'un modèle numérique de vagues, basé sur l'environnement WAVEWATCH®III, permet de constater que ces modèles sont qualitativement valables mais encore quantitativement incorrects. Une des possibilités explorées pour corriger cet effet est la prise en compte de sources de vagues courtes à ±90° de la direction du vent, qui pourraient être associées au déferlement des vagues longues. Une telle source à elle seule n'explique pas les formes des distributions directionnelles observées. D'autres mécanismes pourraient intervenir que de futures investigations pourront tenter de clarifierShort surface gravity waves are ubiquitous at the ocean surface, with lengths from a few tens of meters to a meter typically.Knowing their propagation directions at sea is important in several respects, especially for the understanding of sea-state dynamics, airsea interactions and particles surface drift.Their directional distributions are here investigated in the light of the recent progress made in instrumentation techniques. The analysis of ocean bottom seismo-acoustic noise records allows for the extraction of a quasi-universal behavior which indirectly depends on this distribution through the socalled overlap integral. It is coherent with direct observations of the wave field obtained from tri-dimensional reconstructions of the ocean surface elevation field. While the propagation direction of long waves aligns with the wind direction, short waves progressively detach from it towards small scales (bimodality).Comparing those measurements with the predictions of a spectral numerical wave model, based on WAVEWATCH®III environment, allows to realize that they provide qualitatively correct but quantitatively incorrect predictions. One of the possibilities here explored to correct for it, is by accounting for the sources of energy at ±90° to the wind direction, which could be associated with the breaking of long waves. This source term on its own does not explain the shapes of the observed directional distributions. Other mechanisms could come into play that future investigations will help clarify
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Euvé, Léo-Paul. "Interactions ondes-courant-obstacle : application à la physique des trous noirs." Thesis, Poitiers, 2017. http://www.theses.fr/2017POIT2280/document.
Повний текст джерелаАнотація:
Le projet de recherche consiste à observer en laboratoire la radiation de Hawking, cette prédiction stupéfiante de l'astrophysicien anglais Stephen Hawking faite en 1974 : les trous noirs ne sont pas noirs. Autrement dit, ils n'absorbent pas tout ce qui est à leur portée mais émettent un rayonnement. En plus des complications du fait que ces objets célestes sont à des milliers d'années-lumière, ce rayonnement est tellement faible que cela reviendrait à essayer d'entendre un murmure dans un concert de rock. Mais William Unruh, en 1981, a proposé une solution : utiliser des systèmes hydrodynamiques qui présentent les mêmes équations mathématiques qu'en astrophysique. Plus précisément, dans notre cas, nous utilisons la correspondance entre la propagation des ondes lumineuses au voisinage d'un trou noir et celles des ondes de surface dans un contre-courant rendu inhomogène par la présence d'un obstacle immergé. Pour cela, une compréhension approfondie de la mécanique des ondes de surface est nécessaire (bathymétrie variable, vorticité, non-linéarités…). Du côté technique, une méthode de mesure de surface libre a été développée et optimiséeThe aim of the PhD is the observation the Hawking radiation in the laboratory, this astounding prediction of the English astrophysicist Stephen Hawking made in 1974: black holes are not black. In other words, they do not absorb anything within reach but emit a radiation. In addition to the complications of the fact that these celestial objects are thousands of light years away, this radiation is so weak that it would be like trying to hear a whisper in a rock concert. But William Unruh, in 1981, proposed a solution: to use hydrodynamic systems which have the same mathematical equations as in astrophysics. More precisely, in our case, we use the correspondence between the propagation of light in the vicinity of a black hole and surface waves propagation on a inhomogeneous countercurrent (due to the presence of a submerged obstacle). For this, a thorough understanding of the surface waves physics is necessary (variable bathymetry, vorticity, non-linearities ...). On the technical side, a free surface measurement method has been developed and optimized
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Artru, Juliette. "Observations au sol ou par satellite et modélisation des signaux ionosphériques post-sismiques." Paris, Institut de physique du globe, 2001. http://www.theses.fr/2001GLOB0006.
Повний текст джерелаАнотація:
Depuis 1960 de fortes perturbations de l'ionosphère consécutives à des tremblements de Terre ont mis en évidence le couplage dynamique entre la Terre solide et l'atmosphère. De nombreuses observations de phénomènes associés ont depuis été réalisées, par des mesures au sol ou par satellite. Nous présentons ici une étude de ces phénomènes, fondée d'une part sur la modélisation de ce couplage par les méthodes sismologiques, d'autre part sur le développement de nouveaux outils d'observation adaptés à ce nouveau champ de recherches. Ce travail s'inscrit dans le cadre de la préparation de la mission DEMETER (microsatellite CNES dédié à l'observation des signaux ionosphériques induits par l'activité sismique ou volcanique, dont le lancement est prévu en 2003). La première partie présente les différentes observations en liaison avec le couplage Terre atmosphère, et leur interprétation. La deuxième partie est dédiée à l'établissement d'une extension des méthodes de calcul de modes propres permettant de calculer des sismogrammes synthétiques pour une source et une station situées soit dans la Terre solide, soit dans l'océan ou l'atmosphère. Les synthétiques calculés par sommation de modes, pour une source sismique, montrent un bon accord avec les données fournies par le sondeur Doppler du CEA. La troisième partie présente les travaux réalisés pour développer de nouveaux outils d'observation dans l'ionosphère, notamment au dessus de zones à forte activité sismique, à partir des réseaux GPS denses, tels ceux de Californie ou du Japon. Nous développons enfin en conclusion les perspectives ouvertes par les signaux sismo-atmosphériques, que ce soit dans les champs de la sismologie ou de l'aéronomie
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Fochesato, Christophe. "Modèles numériques pour les vagues et les ondes internes." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2004. http://tel.archives-ouvertes.fr/tel-00132969.
Повний текст джерелаАнотація:
La première partie de la thèse concerne le calcul numérique des ondes de gravité en 3D. Le modèle résout les équations d'Euler incompressibles avec surface libre pour un écoulement potentiel. L'association de l'Algorithme des Multipôles Rapides avec la Méthode des Eléments aux Frontières permet d'améliorer significativement l'efficacité du modèle. Deux applications sont alors considérées : le déferlement d'une onde solitaire sur un fond tridimensionnel et la focalisation spatiale générée par un batteur à houle. Dans la seconde partie, une étude plus en amont est effectuée dans le contexte des ondes internes en deux dimensions. A l'aide d'un système de type Korteweg de Vries, des ondes solitaires généralisées sont discutées dans le cas où la vitesse approche la valeur critique correspondant à l'apparition des fronts. Ces solutions résultent de la résonance entre une onde solitaire large ayant une amplitude limite et une onde courte, qui se propagent à la même vitesse de phase.
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Nguyen, Huu Ha. "Analyse de la surface libre dans un canal par une méthode optique : application à l'impact des vagues sur une structure." Le Havre, 2008. http://www.theses.fr/2008LEHA0004.
Повний текст джерелаАнотація:
Cette thèse a pour objectif d'analyser la surface libre dans un canal à houle par une mesure optique. Cette nouvelle technique de mesure consiste à utiliser une caméra pour enregistrer l’évolution spatio-temporelle de la surface libre dans un canal à parois vitrées où l'eau est traitée par fluorescence induite par laser (FIL). Le bon contraste eau-air obtenu sur les images acquises permet de déterminer, avec précision, la position de la surface libre. Chaque rangée de pixels peut fournir une évolution ponctuelle de la surface libre en fonction du temps comme un outil de mesure ponctuelle de la surface libre traditionnel, d'où l'obtention d’une très grande résolution spatiale. Cette mesure permet de mettre à l'épreuve la méthode de discrimination des différents modes propagatifs de la houle devant une structure réfléchissante en utilisant quatre sondes fixes de Lin et al. (2004). L'utilisation de cette méthode avec des mesures optiques met en évidence la pertinence de la méthode sur la séparation des modes fondamentaux et des difficultés rencontrées lors de son application pour l'obtention des modes harmoniques. Les mêmes conclusions sont tirées quand on effectue l'étude comparative entre la séparation des houles par quatre sondes fixes résistives et celle par deux sondes mobiles de Brossard et al. (2000). La forme de la surface libre obtenue par mesure optique permet, par ailleurs, de caractériser la déformation de la surface libre à proximité d'une structure marine réfléchissante en fonction de l'inclinaison de la paroi d'impact. A cet effet, plusieurs paramètres associés à la forme extrême de la surface libre sont analysés en fonction de l'orientation de la paroiThis PhD study aims to analyze the free surface within a wave channel by using a new optical measurement. This process uses a video and a laser induced fluorescence to visualize the water movement within a wave channel equipped with glass walls. The good contrast between the water and the air obtained on the captured images allows to detect accurately the free surface. A pixel range can give one punctual evolution of the free surface like a traditional punctual measurement of the free surface (for example: resistive probe). So the space resolution of the free surface can be obtained with a very high resolution. This optical measurement opens an in-depth investigation on the decomposition of incident and reflected harmonic waves using four wave gauges proposed by Lin et al. (2004). On the one side, it confirms the good pertinence of this method with the fundamental waves. On the other side, some difficulties appear about the estimation of higher harmonic waves. The same conclusions are found by comparing the four fixed gauges method of Lin et al. (2004) with the moving probes method of Brossard et al. (2000). This new measurement method allows to characterize the different behaviours of the free surface nearby a sloping marine structure according to the structure inclinations. For this purpose, various parameters associated with the extreme forms of the free surface are analyzed in relation to the structure inclination
Книги з теми "Onde surface gravite"
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Bridges, John C. Evolution of the Martian Crust. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190647926.013.18.
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This is an advance summary of a forthcoming article in the Oxford Encyclopedia of Planetary Science. Please check back later for the full article.Mars, which has a tenth of the mass of Earth, has cooled as a single lithospheric plate. Current topography gravity maps and magnetic maps do not show signs of the plate tectonics processes that have shaped the Earth’s surface. Instead, Mars has been shaped by the effects of meteorite bombardment, igneous activity, and sedimentary—including aqueous—processes. Mars also contains enormous igneous centers—Tharsis and Elysium, with other shield volcanoes in the ancient highlands. In fact, the planet has been volcanically active for nearly all of its 4.5 Gyr history, and crater counts in the Northern Lowlands suggest that may have extended to within the last tens of millions of years. Our knowledge of the composition of the igneous rocks on Mars is informed by over 100 Martian meteorites and the results from landers and orbiters. These show dominantly tholeiitic basaltic compositions derived by melting of a relatively K, Fe-rich mantle compared to that of the Earth. However, recent meteorite and lander results reveal considerable diversity, including more silica-rich and alkaline igneous activity. These show the importance of a range of processes including crystal fractionation, partial melting, and possibly mantle metasomatism and crustal contamination of magmas. The figures and plots of compositional data from meteorites and landers show the range of compositions with comparisons to other planetary basalts (Earth, Moon, Venus). A notable feature of Martian igneous rocks is the apparent absence of amphibole. This is one of the clues that the Martian mantle had a very low water content when compared to that of Earth.The Martian crust, however, has undergone hydrothermal alteration, with impact as an important heat source. This is shown by SNC analyses of secondary minerals and Near Infra-Red analyses from orbit. The associated water may be endogenous.Our view of the Martian crust has changed since Viking landers touched down on the planet in 1976: from one almost entirely dominated by basaltic flows to one where much of the ancient highlands, particularly in ancient craters, is covered by km deep sedimentary deposits that record changing environmental conditions from ancient to recent Mars. The composition of these sediments—including, notably, the MSL Curiosity Rover results—reveal an ancient Mars where physical weathering of basaltic and fractionated igneous source material has dominated over extensive chemical weathering.
Частини книг з теми "Onde surface gravite"
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Mandal, Gautam. "Phase Transitions in One Matrix Models." In Random Surfaces and Quantum Gravity, 151–56. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4615-3772-4_10.
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Ambjørn, J. "Random Surfaces in Dimensions Larger than One." In Random Surfaces and Quantum Gravity, 327–36. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4615-3772-4_21.
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Boulatov, Dmitri. "Multipoint Correlation Functions in One-Dimensional String Theory." In Random Surfaces and Quantum Gravity, 237–41. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4615-3772-4_15.
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Wadia, Spenta R. "Excitations and Interactions in a One Dimensional String Theory." In Random Surfaces and Quantum Gravity, 317–26. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4615-3772-4_20.
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Kazakov, Vladimir. "Bosonic Strings and String Field Theories in One-Dimensional Target Space." In Random Surfaces and Quantum Gravity, 269–306. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4615-3772-4_18.
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Batsukh, Khulan. "Cold Atom Interferometry in Satellite Geodesy for Sustainable Environmental Management." In Civil and Environmental Engineering for the Sustainable Development Goals, 43–54. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-99593-5_4.
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AbstractOur Earth is a complex system. By monitoring the integrated geodetic-geodynamic processes, we can understand its sub-systems and geographical distribution of its resources. With the development of space techniques and artificial satellites, satellite geodesy era started, e.g., it became possible to observe a wide range of processes, occurring both on and below the Earth's surface. Such observations can be exploited not only in environmental activities, but also in societal activities like natural disasters monitoring. Thus, satellite geodesy can bring great benefits to “Climate action”, one of the 17 sustainable development goals of the United Nation: we can estimate the ice-sheet mass balance and study the impact of climate change by monitoring sea levels. This paper aims to investigate the possible implementation of cold atom sensors for future satellite gravity missions, which would improve our current knowledge of the Earth’s gravity field and contribute into the sustainable environmental management. Graphical Abstract
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Naqi, Mohammad, and Aimen Amer. "Structures and Tectonics of Kuwait." In The Geology of Kuwait, 99–115. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-16727-0_5.
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AbstractDespite the surface geology of Kuwait appears to be scarce and most of the country is covered with Quaternary deposits except for a few outcrops of Oligo-Miocene to Pleistocene age, the subsurface geology of Kuwait is quite unique and astonishing. The discovery of hydrocarbon in Kuwait at the beginning of the last century helped geologists to better understand the structural geology of Kuwait especially by utilizing geophysical methods such as potential field methods (e.g., gravity and magnetic) and seismic reflection. Being part of the Arabian Peninsula, the structural geology of Kuwait shares many of the Arabian Peninsula structural trends. The dominant N-S trending structures of the Arabian Plate are manifested in the Kuwait Arch which is one of the major structures of the country where many of the oil and gas oil fields are associated with. Other dominant structural trends of the Arabian Plate such as NE-SW and NW–SE are resembled in Kuwait as Jal Az-Zor and Dibdibah Trough, respectively. Paleo- and in-situ stress analysis is an important subject for oil and gas exploration, and many studies have been commissioned to better understand them in most of the Kuwaiti fields. The present-day in-situ stress in Kuwait is oriented NE-SW resembling the current tectonic setting of the region due to the collision of the Arabian Plate with the Eurasia Plate since the Oligocene. This chapter will present a thorough review of the previous studies discussing the surface and subsurface structural geology of Kuwait.
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Bob, Corneliu, Sorin Dan, Catalin Badea, Aurelian Gruin, and Liana Iures. "Strengthening of the Frame Structure at the Timisoreana Brewery, Romania." In Case Studies of Rehabilitation, Repair, Retrofitting, and Strengthening of Structures, 57–80. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2010. http://dx.doi.org/10.2749/sed012.057.
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<p>Many structures built in Romania before 1970 were designed for gravity loads with inadequate lateral load resistance because earlier codes specified lower levels of seismic loads. Some of these structures are still in service beyond their design life. Also, some deterioration was observed in existing structures due to the actions of different hazard factors. This paper presents the case study of a brewery with reinforced concrete framed structure of five storeys and a tower of nine storeys, which has been assessed and strengthened. The brewery and the tower were built in 1961 and an extension in 1971. An assessment performed in 1999 showed up local damages at slabs, main girders, secondary beams, and columns; concrete carbonation; concrete cover spalled over a large surface; complete corrosion of many stirrups and deep corrosion of main reinforcement; and some broken reinforcement. Such damage was caused by salt solution, CO2, relative humidity RH 80%, and temperatures over 40◦C. Also, inadequate longitudinal reinforcement was deduced≈ from the structural analysis. The initial design, done in 1960, was according to the Romanian codes of that time with provisions at low seismic actions. The structural system weakness is due to present-day high seismic actions. The rehabilitation of the reinforced concrete structure was performed by jacketing with reinforced concrete for the main and secondary beams and columns. In 2003, due to continuous operation and subsequent damage of the structure, a new assessment was required. It was found that some beams and one column were characterized by inadequate main and shear reinforcement as well as corrosion of many stirrups at beams. The strengthening solution adopted was based on carbon fibre reinforced polymer composites for beams and column.</p>
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Sneeuw, Nico, Muriel Bergé-Nguyen, and Jean-François Crétaux. "Physical Heights of Inland Lakes." In International Association of Geodesy Symposia. Berlin, Heidelberg: Springer Berlin Heidelberg, 2023. http://dx.doi.org/10.1007/1345_2023_192.
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AbstractInland satellite altimetry has gained traction over the past decade and is now routinely used to monitor the water levels of rivers, lakes and reservoirs. The accuracy of such inland water height measurements, at least from radar altimetry is still relatively poor from a geodetic viewpoint, namely in the range of several decimeter. Accuracies from spaceborne laser altimetry, in particular from the ICESat-2 mission, are at cm-level, however, and further progress in the radar altimetry domain is expected from swath-based altimetry by the SWOT mission, (to be) launched December 2022. With accuracies down to cm-level one needs to reconsider the height system definition of inland lake surfaces as obtained from satellite altimetry. Conventionally one subtracts a global geoid model from the altimetry-derived ellipsoidal height to obtain an orthometric height. Without wind stress, seiches and other time-variable height disturbances the lake water surfaces will conform to equipotential surfaces in the Earth’s gravity field. Thus lake surfaces are surfaces of constant dynamic height, from which follows that a lake surface cannot be a surface of constant orthometric or normal height. Because equipotential surfaces are inherently non-parallel, two points at a lake surface can and will have different orthometric height. Although being well-understood in physical geodesy, we will here model this effect and quantify it for various case studies. We demonstrate that the effects can be as large as a few dm for large lakes at high altitudes, which is an order of magnitude that is relevant in terms of satellite altimetry error levels.
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Adam, John A. "Scattering of Surface Gravity Waves by Islands, Reefs, and Barriers." In Rays, Waves, and Scattering. Princeton University Press, 2017. http://dx.doi.org/10.23943/princeton/9780691148373.003.0017.
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This chapter focuses on the scattering of surface gravity waves by islands, reefs, and barriers. Surface gravity waves that propagate from the deep ocean to coastal regions may be strongly amplified by reflection, refraction, diffraction, and shoaling due to variation in water depth. Analytical solutions provide an attractive approach to studies on wave scattering, but they are obtainable for only special topographies and simple governing equations. The chapter considers long surface gravity waves (linear shallow water waves) such that the depth of the water is much greater than the vertical free surface displacement and the wavelength is much larger than the depth. The fluid equations are derived directly for the present context. The discussion covers trapped waves, the scattering or S-matrix, submerged circular islands, edge waves on a sloping beach, one-dimensional edge waves on a constant slope, and wave amplication by a sloping beach.
Тези доповідей конференцій з теми "Onde surface gravite"
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Hibiki, Takashi, Tomoji Takamasa, and Mamoru Ishii. "One-Dimensional Drift-Flux Model and Constitutive Equations for Relative Motion Between Phases in Various Two-Phase Flow Regimes at Microgravity Conditions." In 12th International Conference on Nuclear Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/icone12-49037.
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In view of the practical importance of the drift-flux model for two-phase flow analyses at microgravity conditions, the constitutive equations for distribution parameter and drift velocity have been developed for various two-phase flow regimes at microgravity conditions. A comparison of the model with various experimental data over various flow regimes and a wide range of flow parameters taken at microgravity conditions shows a satisfactory agreement. The newly developed drift-flux model has been applied to reduced gravity conditions such as 1.62 and 3.71 cm/s2, which correspond to the Lunar and Martian surface gravities, respectively, and the effect of the gravity on the void fraction in two-phase flow systems has been discussed.
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Chagdali, Mohamed, Soumia Mordane, and KL Maroihi. "Une formulation parabolique des équations de propagation des ondes de gravité en surface." In Journées Nationales Génie Côtier - Génie Civil. Editions Paralia, 2000. http://dx.doi.org/10.5150/jngcgc.2000.005-c.
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Hori, Kohei, Iwao Hayashi, and Nobuyuki Iwatsuki. "Determination of the Tooth Surface Friction Coefficient of a Pair of Mating Gears Based on the Distribution Along the Tooth Profile Precisely Measured With the Gravity Pendulum Method." In ASME 2000 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/detc2000/ptg-14371.
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Abstract A new gravity pendulum method has been proposed in order to precisely measure the tooth surface friction coefficient of a pair of mating gears excluding the bearing loss. In this method, one of the mating gears, which is fixed on a gravity pendulum, is put on the other gear, which is fixed on the ground, and is freely oscillated. The center-to-center distance between the mating gears is kept constant with a flexure hinge mechanism in order to accurately reproduce the relative motion, including rolling and sliding, between the tooth surfaces of practical rotating gears. This method has a great advantage, in that the tooth surface friction co-efficient can be measured in a very small region of the tooth profile, because the initial oscillation amplitude can be set approximately one arc-degree. The distribution of the friction coefficients along the tooth surface has been precisely measured for the exact one pair-, inexact one pair-, and two pair-tooth engagements of an internal gear pair and an external gear pair. Also, the mean values of the distributed tooth surface friction coefficients are calculated by taking the specific sliding between the tooth surfaces into account, and are compared with each other.
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Díaz-Ojeda, H. R., L. M. González, and F. J. Huera-Huarte. "Fluid Structure Interaction Simulations Involving Free Surface." In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77207.
Повний текст джерелаАнотація:
The aim of this paper is to evaluate how much affects the presence of gravity and free-surface to a flexible structure in a classical fluid structure interaction (FSI) problem typically found in off-shore problems and other oceanic applications. The base problem selected is the Turek benchmark case where a deformable plate is attached to the wake of a circular cylinder. To focus on the differences of considering free surface, a simple geometry has been selected and two different situations have been studied: the first one is the classical Turek benchmark, the second is a similar geometry but adding gravity and free surface. The free surface problem was studied placing the structure at different depths and monitoring the deformation and forces on the structure.
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Alfaiz, K., F. Ayyasy, Y. Assyifa, and D. Darisma. "«3rd Asia Pacific Meeting on Near Surface Geoscience & Engineering-Poster Session: Potential Field-107» Identification of Lignite as One of Usable Alternative Energy Using Difference Normalized Burn Ratio (dNBR) Calculated from Landsat-8 Data and Gravity Method in Lam Apeng Village, Aceh Besar District, Aceh Province." In 3rd Asia Pacific Meeting on Near Surface Geoscience & Engineering. European Association of Geoscientists & Engineers, 2020. http://dx.doi.org/10.3997/2214-4609.202071107.
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Kheyfets, Vitaly O., and Sarah L. Kieweg. "Free Surface Coating Flows of Non-Newtonian Gels: 3-D Numerical Simulation of Gravity-Induced Flow." In ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-176696.
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Developing a mechanism capable of protecting the vaginal or rectal epithelium from sexually transmitted pathogens can be an effective tool in the prevention of HIV infection [1]. One such tool can come in the form of a microbicide gel, used to provide a physical barrier and act as a delivery vehicle for its active ingredient [1]. In order for the microbicide to be an effective barrier and delivery vehicle it must have the capability to coat the epithelium for a specific amount of time and sustain its structural integrity under the influence of gravity and other perturbation forces. In addition, to be used as a drug delivery vehicle the microbicide must serve the following functions: coat the surface completely without leaving any of the surface exposed, stay on the surface while influenced by external forces such as gravity and squeezing, and must be able to contain potent concentrations of one or more active microbicidal ingredients.
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Walker, K., A. Posenato Garcia, J. Nunn, and G. Lyman. "CO2 Leak Detection and Conformance Verification Using Borehole Gravity." In SPE Energy Transition Symposium. SPE, 2023. http://dx.doi.org/10.2118/215734-ms.
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Abstract Borehole gravity measured from a vertical Carbon Capture and Storage (CCS) injection well, or nearby observation well, provides a cost-efficient solution for monitoring the reservoir for CO2 flow and the overburden for leaks. In this paper, two CO2 injection reservoir models using piston flow and Buckley-Leveret theory are built to simulate and evaluate surface and borehole gravity signatures associated with CO2 flow through thin and thick reservoirs in deep and shallow scenarios. The sensitivity of gravity to plume parameters is also analyzed. The results demonstrate that the lateral gradient in vertical surface gravity after a year of injection is effective for monitoring shallow reservoirs over relatively long time periods and ineffective for deep reservoirs. However, borehole gravity after only a few months of injection is sensitive to both time-lapse density variations and the lateral extent of the saturation plume in all reservoir thickness and depth scenarios. A competition exists for the dominant parameter controlling the borehole gravity signal between density contrast and plume radius. At the bottom of the borehole above the reservoir, sensitivity is dominated by density contrast. As one ascends the borehole, the distance to the reservoir below increases, which lowers the gravity while increasingly adding contributions to the vertical component of gravity, resulting in the plume radius becoming the most sensitive parameter. It is shown that this enhanced sensitivity enables inversions of borehole gravity, using weighted damped least squares, to sufficiently image the radial variation in density contrast associated with the CO2 plume. Analysis of survey parameters on inversion accuracy shows the benefit of conducting surveys that penetrate the reservoir. The results also show that while surface gravity is not capable of seeing small leaks, borehole gravity can detect the depth of leaks within hundreds of feet from a wellbore by a distinctive cross over along the gravity profile. The estimated plume radius based on a reservoir filling model and the comparison of that predicted smooth gravity profile to the observed profile that is sensitive to leak cross-overs in the confining zone provides a cost-effective measurement that can trigger higher cost surveys for deeper levels of investigation.
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Guo, Dan, Fu-Lei Chu, and Yong-Yong He. "Vibration Analysis of Rotor With Transverse Surface Cracks." In ASME Turbo Expo 2003, collocated with the 2003 International Joint Power Generation Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/gt2003-38041.
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The vibration of cracked rotor is investigated by numerical method. The FEM is used to model the rotor with cracks. Six degrees of freedom are considered in each elemental node. Full 6×6 flexibility matrix is deduced by Papadopoulos and Dimarogonas’ method, and 12×12 stiffness matrix of cracked element is derived. The influence of one or more cracks on the natural frequencies and different modals (including bending modal, torsion modal and longitudinal modal) of cracked rotor is explored. Vibration responses of rotor with open cracks or breathing crack loading by eccentric force and rotor gravity force are obtained and analyzed by numerical integer method and spectral technology. The coupling of lateral, longitudinal and torsion vibrations due to transverse surface crack is studied. It is concluded that the above research is useful in detecting crack in rotor.
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Al-Zayani, Alia I., Pramod D. Patil, Abdulaziz S. Al-Qasim, and Sunil L. Kokal. "An Overview of Advanced Subsurface and Surface Measurements for CCUS Project." In Middle East Oil, Gas and Geosciences Show. SPE, 2023. http://dx.doi.org/10.2118/213510-ms.
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Abstract Monitoring and surveillance (M&S) is one of the key requisites for assessing the effectiveness and success of any CCS/CCUS projects. It will help understand, track, monitor, and predict the Injectant plume migration, flow paths, and breakthrough times. The M&S helps in quantifying sequestered injected gas and any inadvertent leakage. It provides a good understanding of the remaining oil saturation (ROS) and its distribution in the reservoir. A comprehensive and advanced monitoring and surveillance (M&S) program was developed and is currently being deployed to address CCS/CCUS project objectives. The advanced M&S plan incorporates conventional, advanced, and emerging novel technologies for wellbore and inter-well measurements. These include advanced time-lapse pulsed neutron, resistivity, diffusion logs, and bore-hole gravity measurements, cross-well geophysical measurements, water and gas tracers, geochemical, compositional and soil gas analyses, and 4D seismic and surface gravity measurements. Results from monitoring and surveillance technologies provide a better understanding of the reservoir dynamics within the subject area. The results can be used to refine the reservoir simulation model and fine tune its parameters. This paper reviews some proven best practices and draws examples from ongoing projects and related novel technologies being deployed. It will then look at the new horizon for M&S technologies for CCS and CCUS.
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Lavrenov, I. V., and A. V. Novakov. "Interaction of Water Gravity Waves With Elastic Ice Floes." In ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/omae2002-28419.
Повний текст джерелаАнотація:
The self-consistence motion of a fluid and elastically oscillating plates partially covering fluid is simulated numerically. The problem is reduced to simulation solution of the Laplace equation for the fluid and equation of elastic plate oscillations for ice motion. The numerical and analytical solutions, obtained using an integral equation containing the Green function, are compared. In order to solve the problem numerically the boundary elements method for the Laplace equation and the finite element method for the equation describing the elastic plate motion are proposed. The coefficients of surface gravity wave transmission and reflection from the floating plate are estimated. It is shown that the solution can be presented as quasi-periodic one with characteristics determined by the initial value of the wave and ice foe parameters. The ice floe exert a filtering effect on the surface wave spectrum, essentially reducing its most deflectable components.
Звіти організацій з теми "Onde surface gravite"
1
Hayward, N., and V. Tschirhart. A comparison of 3-D inversion strategies in the investigation of the 3-D density and magnetic susceptibility distribution in the Great Bear Magmatic Zone, Northwest Territories. Natural Resources Canada/CMSS/Information Management, 2023. http://dx.doi.org/10.4095/331954.
Повний текст джерелаАнотація:
The inversion of new compilations of aeromagnetic data and gravity data are employed to investigate the 3-D physical property (magnetic susceptibility and density) distribution within the Great Bear magmatic zone. The application of two different software suites (Geosoft VOXI and UBC GIF MAG3D and GRAV3D) affords a comparison of approaches and results. The magnetic susceptibility results are broadly compatible, but Geosoft VOXI enabled more detailed definition of shallow sources. The density results were markedly different in how the model responded to the low-resolution gravity data in characterization of the near-surface. GRAV3D extrapolated shallow sources to surface, whereas Geosoft VOXI smoothed and closed the top of shallow sources below surface. The different magnetic susceptibility and density models can be used to assess the physical property distribution and relationships across the region. One approach, applied here, is to combine the near-surface magnetic susceptibility and density results to identify zones of coincidently high physical properties, a common physical proper relationship associated with IOCG mineral deposits. These integrated models highlight many of the region's known mineral occurrences and reveal other zones for further analysis.
2
Russell, H. A. J., and S. K. Frey. Canada One Water: integrated groundwater-surface-water-climate modelling for climate change adaptation. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/329092.
Повний текст джерелаАнотація:
Canada 1 Water is a 3-year governmental multi-department-private-sector-academic collaboration to model the groundwater-surface-water of Canada coupled with historic climate and climate scenario input. To address this challenge continental Canada has been allocated to one of 6 large watershed basins of approximately two million km2. The model domains are based on natural watershed boundaries and include approximately 1 million km2 of the United States. In year one (2020-2021) data assembly and validation of some 20 datasets (layers) is the focus of work along with conceptual model development. To support analysis of the entire water balance the modelling framework consists of three distinct components and modelling software. Land Surface modelling with the Community Land Model will support information needed for both the regional climate modelling using the Weather Research & Forecasting model (WRF), and input to HydroGeoSphere for groundwater-surface-water modelling. The inclusion of the transboundary watersheds will provide a first time assessment of water resources in this critical international domain. Modelling is also being integrated with Remote Sensing datasets, notably the Gravity Recovery and Climate Experiment (GRACE). GRACE supports regional scale watershed analysis of total water flux. GRACE along with terrestrial time-series data will serve provide validation datasets for model results to ensure that the final project outputs are representative and reliable. The project has an active engagement and collaborative effort underway to try and maximize the long-term benefit of the framework. Much of the supporting model datasets will be published under open access licence to support broad usage and integration.
3
Harris, L. B., P. Adiban, and E. Gloaguen. The role of enigmatic deep crustal and upper mantle structures on Au and magmatic Ni-Cu-PGE-Cr mineralization in the Superior Province. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328984.
Повний текст джерелаАнотація:
Aeromagnetic and ground gravity data for the Canadian Superior Province, filtered to extract long wavelength components and converted to pseudo-gravity, highlight deep, N-S trending regional-scale, rectilinear faults and margins to discrete, competent mafic or felsic granulite blocks (i.e. at high angles to most regional mapped structures and sub-province boundaries) with little to no surface expression that are spatially associated with lode ('orogenic') Au and Ni-Cu-PGE-Cr occurrences. Statistical and machine learning analysis of the Red Lake-Stormy Lake region in the W Superior Province confirms visual inspection for a greater correlation between Au deposits and these deep N-S structures than with mapped surface to upper crustal, generally E-W trending, faults and shear zones. Porphyry Au, Ni, Mo and U-Th showings are also located above these deep transverse faults. Several well defined concentric circular to elliptical structures identified in the Oxford Stull and Island Lake domains along the S boundary of the N Superior proto-craton, intersected by N- to NNW striking extensional fractures and/or faults that transect the W Superior Province, again with little to no direct surface or upper crustal expression, are spatially associated with magmatic Ni-Cu-PGE-Cr and related mineralization and Au occurrences. The McFaulds Lake greenstone belt, aka. 'Ring of Fire', constitutes only a small, crescent-shaped belt within one of these concentric features above which 2736-2733 Ma mafic-ultramafic intrusions bodies were intruded. The Big Trout Lake igneous complex that hosts Cr-Pt-Pd-Rh mineralization west of the Ring of Fire lies within a smaller concentrically ringed feature at depth and, near the Ontario-Manitoba border, the Lingman Lake Au deposit, numerous Au occurrences and minor Ni showings, are similarly located on concentric structures. Preliminary magnetotelluric (MT) interpretations suggest that these concentric structures appear to also have an expression in the subcontinental lithospheric mantle (SCLM) and that lithospheric mantle resistivity features trend N-S as well as E-W. With diameters between ca. 90 km to 185 km, elliptical structures are similar in size and internal geometry to coronae on Venus which geomorphological, radar, and gravity interpretations suggest formed above mantle upwellings. Emplacement of mafic-ultramafic bodies hosting Ni-Cr-PGE mineralization along these ringlike structures at their intersection with coeval deep transverse, ca. N-S faults (viz. phi structures), along with their location along the margin to the N Superior proto-craton, are consistent with secondary mantle upwellings portrayed in numerical models of a mantle plume beneath a craton with a deep lithospheric keel within a regional N-S compressional regime. Early, regional ca. N-S faults in the W Superior were reactivated as dilatational antithetic (secondary Riedel/R') sinistral shears during dextral transpression and as extensional fractures and/or normal faults during N-S shortening. The Kapuskasing structural zone or uplift likely represents Proterozoic reactivation of a similar deep transverse structure. Preservation of discrete faults in the deep crust beneath zones of distributed Neoarchean dextral transcurrent to transpressional shear zones in the present-day upper crust suggests a 'millefeuille' lithospheric strength profile, with competent SCLM, mid- to deep, and upper crustal layers. Mechanically strong deep crustal felsic and mafic granulite layers are attributed to dehydration and melt extraction. Intra-crustal decoupling along a ductile décollement in the W Superior led to the preservation of early-formed deep structures that acted as conduits for magma transport into the overlying crust and focussed hydrothermal fluid flow during regional deformation. Increase in the thickness of semi-brittle layers in the lower crust during regional metamorphism would result in an increase in fracturing and faulting in the lower crust, facilitating hydrothermal and carbonic fluid flow in pathways linking SCLM to the upper crust, a factor explaining the late timing for most orogenic Au. Results provide an important new dataset for regional prospectively mapping, especially with machine learning, and exploration targeting for Au and Ni-Cr-Cu-PGE mineralization. Results also furnish evidence for parautochthonous development of the S Superior Province during plume-related rifting and cannot be explained by conventional subduction and arc-accretion models.