Relevant bibliographies by topics / Propagative regime

Academic literature on the topic 'Propagative regime'

Author: Grafiati

Published: 7 July 2024

Last updated: 7 July 2024

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Journal articles on the topic "Propagative regime":

Tsurimaki, Y., P.-O. Chapuis, J. Okajima, A. Komiya, S. Maruyama, and R. Vaillon. "Transition from the incoherent to the coherent regime for propagative-wave based thermal radiation." Journal of Physics: Conference Series 676 (January 2016): 012023. http://dx.doi.org/10.1088/1742-6596/676/1/012023.

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Scalari, Giacomo, Shima Rajabali, Elsa Jöchl, Sergej Markmann, Simone de Liberato, Erika Cortese, Mattias Beck, and Jérôme Faist. "Non-locality and single meta-atom spectroscopy in THz Landau polaritons." EPJ Web of Conferences 266 (2022): 08013. http://dx.doi.org/10.1051/epjconf/202226608013.

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We will discuss, theoretically and experimentally, the existence of a limit to the possibility of arbitrarily increasing electromagnetic confinement in polaritonic systems, where strongly sub-wavelength fields can excite a continuum of high-momenta propagative magnetoplasmons. This leads to peculiar nonlocal polaritonic effects, as certain polaritonic features disappear and the system enters in the regime of discrete-to-continuum strong coupling. We will as well present experiments reporting spectroscopy of a single, ultrastrongly coupled, highly subwavelength resonator operating at 300 GHz.

Dupuy, Bastien, and Alexey Stovas. "Influence of frequency and saturation on AVO attributes for patchy saturated rocks." GEOPHYSICS 79, no. 1 (January 1, 2014): B19—B36. http://dx.doi.org/10.1190/geo2012-0518.1.

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Partially saturated rocks are considered to be major sources of seismic wave velocity dispersion and attenuation in recorded real data. From the physical description of partially saturated gas-water and oil-water reservoirs, we use upscaling theories to compute an equivalent frequency-dependent porous medium. These homogenization methods are associated with mesoscale description of attenuation and dispersion coming from wave-induced flow phenomena. To compute wave propagation, we use numerical codes in the frequency domain that allow us to take into account all the frequency-dependent parameters without approximation or local time steps. In this way, the Biot slow compressional wave is well modeled and its partially diffusive, partially propagative behavior is completely considered. The attenuation and dispersion of the waves in such media are coming partly from the wave mode conversion into diffusive slow waves, not visible on seismograms. But the amplitude of propagative P- and S-waves are mainly affected by these energy losses at interfaces. Using full waveform modeling, we investigate the amplitude versus offset (AVO) attributes with respect to saturation and frequency. For a simple three-layer case, we compute poroelastic wave propagation, extract maximum amplitude with respect to angle, and, through a least-square fitting method, we obtain the AVO attributes for PP- and PS-reflected events. Due to the influence of mesoscale induced-flow phenomena and relatively to the regime of the Biot slow wave, the main results show a strong variability of the AVO attributes with the frequency and a lower variability with the saturation for reflected PP or PS events. We show that gas-water and oil-water systems have similar behaviors. Strong differences between patchy saturation and effective fluid phase theories are highlighted, especially at high frequency, for PP events and for gas-water systems. Then, we conclude that these AVO attributes carry information about the saturation that can be used to estimate the saturation variations in time-lapse studies.

Joly, Nicolas, and Petr Honzík. "Numerical Modelling of Boundary Layers and Far Field Acoustic Propagation in Thermoviscous Fluid." Acta Acustica united with Acustica 105, no. 6 (November 1, 2019): 1137–48. http://dx.doi.org/10.3813/aaa.919392.

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To model linear acoustics in a thermoviscous fluid in open domain and time-harmonic regime, a Finite Element formulation in a bounded meshed domain is combined with the integral representation of the field for the propagative solution. The integrals are non-singular and involve the only Finite Element node values for temperature variation and particle velocity variables. To overcome the non-uniqueness of solutions at fictitious resonant frequencies, a Burton-Miller combination of integral representation is used. This formulation is suitable to compute acoustic radiation, scattering and diffraction by objects or mutual interaction between transducers. Two-dimensional computational experiments are presented in an infinite, open domain (exterior), showing that the model can be achieved in meshing only a thin domain surrounding the physical boundaries of a device.

Ramananarivo, Sophie, Ramiro Godoy-Diana, and Benjamin Thiria. "Passive elastic mechanism to mimic fish-muscle action in anguilliform swimming." Journal of The Royal Society Interface 10, no. 88 (November 6, 2013): 20130667. http://dx.doi.org/10.1098/rsif.2013.0667.

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Swimmers in nature use body undulations to generate propulsive and manoeuvring forces. The anguilliform kinematics is driven by muscular actions all along the body, involving a complex temporal and spatial coordination of all the local actuations. Such swimming kinematics can be reproduced artificially, in a simpler way, by using the elasticity of the body passively. Here, we present experiments on self-propelled elastic swimmers at a free surface in the inertial regime. By addressing the fluid–structure interaction problem of anguilliform swimming, we show that our artificial swimmers are well described by coupling a beam theory with the potential flow model of Lighthill. In particular, we show that the propagative nature of the elastic wave producing the propulsive force is strongly dependent on the dissipation of energy along the body of the swimmer.

Chen, Shu-Hua, and Yuh-Lang Lin. "Effects of Moist Froude Number and CAPE on a Conditionally Unstable Flow over a Mesoscale Mountain Ridge." Journal of the Atmospheric Sciences 62, no. 2 (February 1, 2005): 331–50. http://dx.doi.org/10.1175/jas-3380.1.

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Abstract In this study, idealized simulations are performed for a conditionally unstable flow over a two-dimensional mountain ridge in order to investigate the propagation and types of cloud precipitation systems controlled by the unsaturated moist Froude number (Fw) and the convective available potential energy (CAPE). A two-dimensional moist flow regime diagram, based on Fw and CAPE, is proposed for a conditionally unstable flow passing over a two-dimensional mesoscale mountain ridge. The characteristics of these flow regimes are 1) regime I: flow with an upstream-propagating convective system and an early, slowly moving convective system over the mountain; 2) regime II: flow with a long-lasting orographic convective system over the mountain peak, upslope, or lee slope; 3) regime III: flow with an orographic convective or mixed convective and stratiform precipitation system over the mountain and a downstream-propagating convective system; and 4) regime IV: flow with an orographic stratiform precipitation system over the mountain and possibly a downstream-propagating cloud system. Note that the fourth regime was not included in the flow regimes proposed by Chu and Lin and Chen and Lin. The propagation of the convective systems is explained by the orographic blocking and density current forcing associated with the cold-air outflow produced by evaporative cooling acting against the basic flow, which then determines the propagation and cloud types of the simulated precipitation systems.

Hall, Charles R., and Dewayne L. Ingram. "Carbon Footprint and Production Costs Associated with Varying the Intensity of Production Practices During Field-grown Shrub Production." HortScience 50, no. 3 (March 2015): 402–7. http://dx.doi.org/10.21273/hortsci.50.3.402.

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This research uses a life cycle analysis and economic engineering approach to determine the costs and global warming potential (GWP) of production and post-production practices associated with Taxus ×media ‘Densiformis’, which is often grown using a more capital-intensive regime during the propagative and harvesting stages than the typical field-grown shrub. Total variable costs incurred during the rooted cutting stage were slightly over $0.24 per marketable rooted cutting. This was made up of $0.1966, $0.032, and $0.0127 for labor, materials, and equipment operating costs, respectively. The GWP of materials and equipment used during the rooted cutting stage of production was 0.0097 and 0.2762 kg CO2 equivalent (CO2e), respectively. Equipment costs in this phase were predominantly from heating the greenhouse (92%) and the greenhouse heating functions comprised 95% of the rooting cutting GWP. GWP during the post-farm gate stage was 2.4506 kg CO2e per marketable shrub but was offset by 12.5522 kg CO2 being sequestered in the shrub during its time in the landscape and weighted over the 100-year assessment period, leaving a net GWP of –8.1824 kg CO2e per marketable shrub by the end of the life cycle. Total takedown and disposal costs (labor) after an assumed 50-year life in the landscape were $9.0610. During the entire life cycle from cutting to landscape to takedown and disposal, total variable costs incurred were $17.9856 per shrub. These findings are consistent with previous studies in that the GWP is positive when considering the entire life cycle of the shrub from propagation to eventual removal from the landscape. Knowing the carbon footprint of production and distribution components of field-grown shrubs will help nursery managers understand the environmental costs associated with their respective systems and evaluate potential system modifications to reduce greenhouse gas (GHG) emissions.

Garnier, Josselin. "Wave propagation in random media: beyond Gaussian statistics." ESAIM: Proceedings and Surveys 74 (November 2023): 63–89. http://dx.doi.org/10.1051/proc/202374063.

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In this paper we review some aspects of wave propagation in random media. In the physics literature the picture seems simple: for large propagation distances, the wavefield has Gaussian statistics, mean zero, and second-order moments determined by radiative transfer theory. The results for the first two moments can be proved under general circumstances by multiscale analysis. The Gaussian conjecture for the statistical distribution of the wavefield can be proved in some propagation regimes, such as the white-noise paraxial regime that we address in the first part of this review. It may, however, be wrong in other regimes, such as in randomly perturbed open waveguides, that we address in the second part of this review. In the third and last part, we reconcile the two results by showing that the Gaussian conjecture is restored in randomly perturbed open waveguides in the high-frequency regime, when the number of propagating modes increases.

FELIKS, YIZHAK. "An analytical model of gravity currents in a stable atmosphere." Journal of Fluid Mechanics 420 (October 10, 2000): 27–46. http://dx.doi.org/10.1017/s0022112000001488.

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An analytical solution to the nonlinear equations of motion and thermodynamic energy for gravity currents propagating in stable atmosphere is found. This solution differs from the previous analytical studies in several aspects. In our solution the head of the gravity current is a strong vortex and the dynamics are non-hydrostatic. The solution has two regimes: (i) a supercritical regime when the Froude number Fr = (c – U)/Na is larger than 1 – in this case the cold front is local; (ii) a subcritical regime when Fr is smaller than 1. Here, ahead of the front there is a disturbance of nonlinear gravity waves. The scale of the wave and its amplitude increase as the Froude number decreases.We found that the square of the speed of the gravity current (relative to the synoptic wind) is proportional to the mean drop of potential temperature over the front area times the front height a. The constant of proportionality is function of the environmental conditions. The thermal, velocity and vorticity fields can be described by non-dimensional structure functions of two numbers: pa = 1/Fr and ka. The amplitude of the structure functions is proportional to (c – U) 2/a for the thermal field, to (c – U) for the velocity field, and to (c – U)/a for the vorticity field.The propagation is studied in terms of the vorticity equation. The horizontal gradient of the buoyancy term always tends to propagate the cold front. The nonlinear advection term in most of the cases investigated here tends to slow the propagation of the gravity current. The propagation of the disturbance of nonlinear gravity waves ahead of the front in regime (ii) in most of the cases is due to the buoyancy term. The nonlinear advection term tends to slow the propagation when the synoptic wind blows in the direction opposite to that of the front propagation, and increase the propagation when the synoptic wind blows in the direction of propagation.

Saini, A., V. M. Vyas, Thokala Soloman Raju, S. N. Pandey, and Prasanta K. Panigrahi. "Super and subluminal propagation in nonlinear Schrödinger equation model with self-steepening and self-frequency shift." Journal of Nonlinear Optical Physics & Materials 24, no. 03 (September 2015): 1550033. http://dx.doi.org/10.1142/s0218863515500332.

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We investigate exact traveling wave solutions of higher order nonlinear Schrödinger equation (NLSE) in the absence of third-order dispersion, which exhibit nontrivial self-phase modulation. It is shown that the corresponding dynamical equation, governing the evolution of intensity in the femtosecond regime, is that of NLSE with a source. The exact localized solutions to this system can have both super and subluminal propagation belonging to two distinct classes. A number of these solitons exhibit chirality, thereby showing preferential propagation behavior determined by group velocity dispersion. Both localized bright and dark solitons are found in complementary velocity and experimental parameter domains, which can exist for anomalous and normal dispersion regimes. It is found that dark solitons in this system propagate with nonzero velocity, unlike their counterpart in nanosecond regime. Interestingly, subluminal propagation is observed for solitons having a nontrivial Padé type intensity profile.

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Dissertations / Theses on the topic "Propagative regime":

Lalloz, Samy. "De la diffusion à la propagation d'ondes en magnétohydrodynamique bas-Rm : études théorique et expérimentale." Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALI020.

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L'objectif de cette thèse est de clarifier les conditions d'émergence en métaux liquides des ondes d'Alfvén dans un domaine géométriquement contraint. La première partie de ce travail de recherche est consacrée à une étude linéaire des ondes d'Alfvén dans l'approximation bas-Rm et en régime non inertiel. La seconde partie porte sur l'étude expérimentale d'un écoulement oscillant forcé électriquement, soumis à un champ magnétique axial, statique et uniforme, et confiné entre deux parois horizontales rigides, sans glissement et électriquement isolantes.Dans l'étude théorique menée, une première partie vise à discuter la relation de dispersion pour la dynamique des ondes d'Alfvén. Elle présente les conséquences liées à des gradients (mécaniques et magnétiques) perpendiculaires au champ magnétique imposé, plus particulièrement la manière dont la propagation de l'onde est ainsi modifiée. Dans la deuxième partie, un vortex axisymétrique confiné entre deux parois horizontales isolées électriquement et sans glissement est magnétiquement forcé à une fréquence donnée. Ce forçage prend en compte le rayon du vortex afin d'étudier l'impact des gradients transversaux sur la dynamique de l'écoulement. Une étude semi-analytique de la dynamique de l'écoulement est à nouveau réalisée dans un cadre bas-Rm et non inertiel. Cette étude, réalisée en faisant varier la fréquence de forçage et l'intensité du champ magnétique, met en évidence deux régimes très distincts, à savoir un premier régime oscillant-diffusif, régi par la compétition entre l'effet pseudo-diffusif de la force de Lorentz et le terme instationnaire de la quantité de mouvement, et un second régime, propagatif, régi par les ondes d'Alfvén et obtenu pour des fréquences de forçage plus élevées. L'étude met également en évidence l'impact des gradients transversaux sur ce régime propagatif. En plus de sur-amortir les ondes, les gradients transversaux modifient les fréquences naturelles des pics de résonance d'ondes, lesquels résultent de la superposition d'ondes incidentes et réfléchies entre les parois du domaine d'étude.Parallèlement à ce travail théorique, un dispositif a été conçu afin d'étudier expérimentalement la dynamique d'écoulements oscillants sous un champ magnétique (jusqu'à 10T). Un écoulement est forcé dans un récipient cubique de 15 cm x 15 cm x 10 cm au moyen d'un courant alternatif injecté à l'aide de quatre électrodes situées sur la plaque inférieure. En utilisant une instrumentation basée sur les différences locales de potentiel électrique aux niveau des plaques (d'Hartmann) supérieure et inférieure, nous validons les prédictions du modèle. Plus précisément, nous retrouvons un régime propagative modifié par les gradients transversaux ainsi que le régime oscillant-diffusif, obtenu pour des fréquences de forçage plus faibles.En plus des résultats obtenus à la fréquence de forçage, un premier aperçu des signaux obtenus à d'autres fréquences est présenté. Certains des pics de fréquence obtenus ne pouvant pas être expliqués par une approche linéaire, nous suggérons qu'ils sont générés par des interactions non linéaires d'ondes d'Alfvén. En outre, une étude préliminaire sur le pic à la première harmonique de la fréquence de forçage montre qu'il est très probablement associé à des ondes d'Alfvén
The thesis aims to clarify the conditions for Alfvén waves to propagate in a closed liquid metal domain. A first part of the research work presented is dedicated to a linear study of Alfvén waves in the low-Rm approximation and under the inertia-less limit. The second part is the experimental investigation of an electrically-induced oscillating flow subjected to an axial, static and uniform magnetic field and confined between two electrically insulating and no-slip horizontal walls.The theoretical study is itself split into two sub-parts. The first one aims to discuss the dispersion relation which contains the Alfvén wave dynamics. It presents the consequences of (mechanical and magnetic) gradients perpendicular to the imposed magnetic field. As such transverse gradients tend to impede the wave propagation. In the second sub-part an axisymmetric vortex confined between to electrically insulated and no-slip horizontal walls is magnetically forced at a given frequency. This forcing is radially dependent so as to study the impact of transverse gradients on the flow dynamics. A semi-analytical investigation of the flow dynamics is again carried out in the low-Rm approximation and under the inertia-less limit. This investigation is performed by varying the forcing frequency and the magnetic field intensity. This brings to emphasize two very distinct regimes for the oscillating vortex:- an oscillating-diffusive regime governed by the competition between pseudo-diffusive effects of the Lorentz force and the unsteady term of the momentum- a truly propagative regime, obtained for higher forcing frequencies, found definitelygoverned by Alfvén waves.The study also highlights how the propagative regime can be affected by transverse gradients. In addition to over-damping the waves, transverse gradients are found to modify the natural frequencies for which wave resonance peaks result from the superimposition of incident and reflected waves in the container.Beside this theoretical work, a setup has been designed in order to experimentally investigate the dynamics of oscillating flows under a strong magnetic field (up to 10T). A flow was forced in a cuboid vessel 15 cm x 15 cm x 10 cm by means of AC currents injected through a cartesian grid of four electrodes located at the bottom plate. Using instrumentation based on the measurement of local electric potential differences at the top and bottom horizontal (Hartmann) plates, we validate model's prediction. More precisely, a propagative dynamics in the presence of transverse gradients is recovered. The oscillating-diffusive regime is also recovered from experiments performed at small enough forcing frequency.In addition to results obtained at the forcing frequency, a first insight of signals obtained at other frequencies is shown. Frequency peaks obtained, eg the harmonics of the forcing frequency, are demonstrated not to be explained by a linear approach. We suggest that Alfvén wave non-linear interactions are a good candidate to explain these peaks. A preliminary study further shows that peaks at the first harmonic are likely to be Alfvén waves

ELALOUFI, Rachid. "Propagation du rayonnement en milieu diffusant. Etude de la transition entre le regime balistique et le regime diffusif et des fluctuations temporelles d'intensite." Phd thesis, Ecole Centrale Paris, 2003. http://tel.archives-ouvertes.fr/tel-00003084.

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Nous étudions la propagation d'une impulsion lumineuse à
travers un milieu diffusant. La propagation peut être décrite
par l'équation de transfert radiatif en régime dynamique
(ETR). Nous proposons une méthode de résolution en
géometrie plane. Elle consiste à appliquer la méthode
des ordonnées discrètes dans le domaine fréquentiel de
l'ETR. Nous calculons ainsi le flux d'énergie directionnel
transmis et rétrodiffuse en fonction du temps et de l'angle.

Dans la seconde partie, nous étudions la validité de
l'approximation de la diffusion. Cependant, l'expression théorique
du coefficient D en milieu absorbant varie selon l'approche
adoptée. Une nouvelle approche fondée sur l'analyse du mode
fondamental de l'ETR est développée. Sans faire aucune
hypothèse concernant le niveau d'absorption, nous obtenons une
nouvelle définition et interprétation de D.

La troisième partie est consacrée à l'étude de la
transition entre le regime balistique et le regime
diffusif. Nous montrons que les reflexions internes jouent un
rôle important pour les systèmes à faible épaisseur
optique. Nous montrons ainsi que le régime diffusif est atteint
aux temps longs, pour des systèmes de taille 8L ou L est la
longueur de transport.

Enfin, dans la derniere partie, nous modélisons la
corrélation temporelle du signal diffuse. Deux théories
(QELS et DWS) permettent de modéliser respectivement le signal en
diffusion simple et en régime diffusif. Nous avons
développe un modèle décrivant les deux régimes
ainsi que le régime intermédiaire. Le modèle est fondé
sur une approche de type marche au hasard et sur la résolution de
l'équation de transfert radiatif dynamique. Ce modèle a permis
de décrire des expériences récentes de mesures de
fluctuations temporelles de champs et d'intensite dans le
régime de diffusion multiple intermédiaire.

JAKOBER, FRANCOIS. "Etude de la propagation d'impulsions laser ultra-intenses dans un plasma sous-dense en regime faiblement relativiste." Paris 11, 1996. http://www.theses.fr/1996PA112222.

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Nous presentons dans ce manuscrit une etude de l'interaction d'impulsions laser ultra-intenses avec un plasma sous-dense. Nous nous sommes plus particulierement interesses a l'influence des effets relativistes sur la propagation et a la mise en evidence de l'autofocalisation relativiste. Celle-ci intervient lorsque la puissance du laser est superieure a une puissance critique d'autofocalisation. Pour une puissance laser inferieure a cette puissance critique, la divergence du faisceau est reduite apres interaction avec le plasma. Une modelisation analytique et numerique de l'interaction montre que la non-linearite relativiste est responsable de cet effet observe experimentalement. Lorsque la puissance laser depasse la puissance critique, l'autofocalisation relativiste a pu etre clairement mise en evidence. Alors que la focalisation du faisceau dans le vide permet d'atteindre un eclairement de 3x10#1#8 w/cm#2, la simulation des experiences montrent qu'un eclairement de 5x10#1#9 w/cm#2 est atteint dans le plasma apres autofocalisation. D'autre part, des foyers multiples apparaissent et l'impulsion est alors guidee sur une distance tres superieure a la longueur de rayleigh. Pour des impulsions d'une picoseconde de duree et un plasma d'hydrogene, les ions ont le temps de bouger pendant la duree de l'impulsion, favorisant l'apparition d'un canal de densite electronique. Celui-ci est alors responsable d'une accentuation du phenomene de reduction de divergence et la puissance critique d'autofocalisation peut etre reduite dans nos experiences d'un facteur deux

CONSTANTOPOULOS, CONSTANTIN. "Etude theorique, numerique et experimentale de la propagation d'ondes acoustiques dans des empilements metalliques desordonnes en regime lineaire et non lineaire." Paris 6, 1998. http://www.theses.fr/1998PA066447.

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Nous etudions, theoriquement, numeriquement et experimentalement, la propagation d'ondes acoustiques dans des systemes unidimensionnels desordonnes constitues par un empilement alterne de couches metalliques d'impedance acoustique differente et d'epaisseur aleatoire. Pour etudier le regime de propagation lineaire, nous avons utilise un formalisme de matrice de transfert qui permet de reduire la recherche du coefficient de transmission d'un empilement a l'etude des proprietes de produits de matrices 2 2 unimodulaires et aleatoires. Contrairement a un milieu parfaitement periodique qui presente des bandes interdites en frequences, un milieu desordonne ne permet pas la propagation des ondes qui sont exponentiellement attenuees. Cette decroissance exponentielle est definie par la longueur de localisation qui est deduite de l'equation self-consistente de dyson-scmidt ; nous avons resolu cette equation par un schema perturbatif qui nous permet de donner la valeur de l'amortissement des ondes dans la limite du faible de desordre (regime de diffusion rayleigh). Nous avons montre numeriquement que pour un empilement realiste sur le plan experimental le comportement du coefficient de transmission est eloigne de la prediction theorique obtenue dans la limite asymptotique. Nous prevoyons l'ouverture des bandes interdites secondaires entre celles de l'empilement periodique que nous avons faiblement desordonne. Pour etudier la propagation en regime non-lineaire nous avons integre numeriquement l'equation differentielle hyperbolique qui regit une telle propagation en utilisant un algorithme d'analyse base sur un schema des differences finies. Sur le plan experimental nous fabriquons les echantillons en chauffant a plusieurs centaines de degres un empilement de feuillets fer et cuivre ou aluminium et cuivre d'une epaisseur respective moyenne de 100 m, enserre dans un cylindre de molybdene. Il est necessaire de determiner une temperature et un temps de recuit ideal pour obtenir une bonne qualite d'interfaces car les metaux choisis forment des phases supplementaires aux interfaces pendant l'interdiffusion thermique. Les echantillons ont ete caracterise par microscopie electronique a balayage et spectrometrie a selection en energie. Les etudes acoustiques ont ete realise selon des techniques hyperfrequences classiques, bases sur la methode pulse-echo en mode transmission. Nous determinons ainsi le spectre de transmission de la structure moyenne sous-jacente qui presente des bandes interdites dans un domaine frequentiel qui s'etale entre 5-30 mhz. Nous mesurons la vitesse de phase en utilisant la methode zero-crossing permettant de mettre en evidence le caractere dispersif du milieu. La mesure de l'attenuation intrinseque d'un materiau multicouche desordonne et la comparaison avec celle d'un echantillon periodique nous a permis de constater l'existence d'une absorption supplementaire due au desordre. Les experiences en regime non-lineaire que nous avons entreprises ont montre que la forte attenuation, liee a la structure granulaire des feuillets, inhibe dans ces empilements les phenomenes non-lineaires, tels que la generation d'harmoniques superieurs.

Rogers, Susan Owen. "Population Biology of the Tan Riffleshell (Epioblasma florentina walkeri) and the Effects of Substratum and Light on Juvenile Propagation." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/36143.

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The federally endangered tan riffleshell (Epioblasma florentina walkeri) is restricted to only one known reproducing population, in Indian Creek, Tazewell County, Virginia. Attempts to recover this species by augmenting relic populations throughout its historic range are aided through knowledge of its population biology and requirements in culture environments. Infestations of host fish (fantail darters, Etheostoma flabellare), obtained from four river drainages, with tan riffleshell glochidia showed that significantly more juveniles transformed per fish from infestations on fantail darters from Indian Creek (mean = 59.22 Â± 10.01) than on fantail darters from the Roanoke River (mean = 9.45 Â± 10.64) (p = 0.024). Number of juveniles from fantail darters collected from Elk Garden and the South Fork Holston River were not significantly different from those of either Indian Creek fish or Roanoke River fish. These results support the hypothesis that mussel-host fish relationships are likely mediated by fish immune responses. Furthermore, this study suggests that this compatibility has resulted from coadaptation between the tan riffleshell and fantail darter populations in Indian Creek.

The tan riffleshell population in Indian Creek was estimated to be 1078 adults (95% CI= 760 - 1853), using Schumacher's modification of Schnabel's maximum likelihood estimator. The sex ratio and size distribution of males and females were approximately equal. Specimen ages, determined from thin-sections of shells, showed that mussels aged by external annuli on shells likely underestimates the true ages of individuals.

Appropriate culture conditions for this species were examined using juveniles of the wavyrayed lampmussel (Lampsilis fasciola) as a surrogate. In the first experiment, juvenile growth and survival was compared between four substratum types (fine sediment, < 120Î¼m; fine sand, 500 Î¼m-800 Î¼m; coarse sand, 1000 Î¼m-1400 Î¼m; and mixed sediment, < 1400 Î¼m) and two light treatments in open versus covered recirculating troughs (2.8 m). Juveniles in fine sediment substratum and covered troughs fared poorest, with 7% survival and growth to only 0.86 mm in length after 16 wk. Juveniles in mixed sediment and open troughs fared best, with 26% survival and growth to 1.09 mm after 16 wk. Additionally, juveniles in fine sand in covered troughs had significantly higher survival (23.1%) than juveniles in fine sediment (p = 0.04), and juveniles in fine sand survived consistently better between light treatments than in the other substrata. There were no significant differences among the other treatments.

A second experiment was performed to determine whether juveniles were responding directly to the presence of light or whether only the increased autochthonous production improved growth and survival. One-half of each of three 2.8 m troughs were covered with 50% shade cloth, while the other sides were left open to ambient light. Additionally, the best and worst sediments from the first experiment (fine sand and fine sediment) were used again to verify the results from the previous experiment. In this case, juveniles in both sides of the troughs grew equally well, but juveniles in the open sides had significantly poorer survival (open mean: 1.78%, sd = 5.01; covered mean: 7.4%, sd = 5.01) (p = 0.046). Fine sediment yielded significantly higher growth of juveniles than fine sand (p = 0.009), with shell lengths of 2.63 mm (sd = 0.075) in fine sediment and 1.94 mm (sd = 0.102) in fine sand. The differences in survival and growth between the two experiments were attributed to differential numbers of chironomids and platyhelminths, which are predators of young juveniles. Additionally, the fine sediment was more tightly packed in the first experiment than in the second, which may have restricted movement and subsequently reduced survival. Light alone likely did not affect juvenile survival and growth; rather, it was seemingly the greater abundance of aufwuchs available as food. This hypothesis was corroborated by a juvenile behavior experiment, which showed that juveniles did not act differently when in tanks not exposed to light versus those open to ambient light.
Master of Science

L'HERMITE, DANIEL. "Comparaisons des descriptions cinetique et coherente pour la modelisation de la propagation de l'impulsion laser en milieu optiquement epais et en regime semi-coherent." Paris 11, 1999. http://www.theses.fr/1999PA112259.

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Dans le procede silva (separation isotopique par laser en vapeur atomique), la photo-ionisation de l'uranium 235 est realisee selectivement a l'aide de plusieurs lasers. Pour utiliser au mieux les photons, les impulsions laser se propagent sur de grandes distances au sein de la vapeur atomique. Au cours de leur trajet, elles subissent eventuellement des deformations spatiales et temporelles qui peuvent abaisser l'efficacite de l'excitation. Pour optimiser celle ci, il est necessaire de savoir calculer l'evolution des caracteristiques des faisceaux laser et de la vapeur sur toute la zone d'interaction. L'objectif de ce travail est de contribuer a la validation d'une approche simplifiee (formulation cinetique) pour decrire les phenomenes lies a la propagation resonante d'une impulsion laser en regime semi-coherent. A cette fin, la demarche qui ete suivie se base sur une etude numerique et une etude experimentale sur l'europium. De leur confrontation est nee la necessite de developper un nouveau code de calcul, euro, dont l'originalite tient a la prise en compte complete de la structure hyperfine et qui reduit significativement l'ecart entre les previsions des codes et les resultats experimentaux. Le code euro sert alors de reference pour etudier dans un certain nombre de situation la pertinence du calcul cinetique.

Bennett, Valerie P. "A microscale study of small crack propagation in multiaxial fatigue." Diss., Atlanta, Ga. : Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/23957.

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Almehmadi, Fares Saleh S. "Secure Chaotic Transmission of Digital and Analog Signals Under Profiled Beam Propagation in Acousto-Optic Bragg Cells with Feedback." University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1426781250.

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Tombul, Serdar. "A numerical study of the validity regimes of weak fluctuation theory for ocean acoustic propagation through random internal wave sound speed fields." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion.exe/07Mar%5FTombul.pdf.

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Thesis (M.S. in Engineering Acoustics and M.S. in Electrical Engineering)--Naval Postgraduate School, March 2007.
Thesis Advisor(s): John Colosi. "March 2007." Includes bibliographical references (p. 81-82 ). Also available in print.

Mai, Phuong Thao. "The potential role of copper binding sites in prion propagation." Doctoral thesis, SISSA, 2014. http://hdl.handle.net/20.500.11767/3905.

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Transmissible spongiform encephalopathies (TSEs) or prion diseases are caused by a post-translational conversion of the normal cellular form of the prion protein (PrPC) into the pathological and infectious isoform denoted as prion or PrPSc. PrPC has been shown as a high-affinity copper-binding protein, and to a lesser extent binding to other divalent cations through the octarepeat region (OR) and the non-OR copper binding sites located in the disordered N-terminal domain. Studies on the role of copper in promoting prion conversion and infectivity yielded controversial results. In this work, we explored the role of histidine residues which are crucial for copper coordination in prion conversion using a combination of cell culture and cell-free approaches. The first evidence was derived from chronically prion-infected neuronal murine cells (ScN2a) transiently expressed in murine PrPC carrying artificial mutations at histidines located both at the OR and non-OR regions. We found that the lack of each histidine in the OR has neither effect on prion replication nor protein maturation and trafficking. Intriguingly, mutagenesis of histidine 95 (H95Y) does enhance prion conversion leading to de novo infectious material formation and cause aberrant accumulation during protein trafficking. Thus, we hypothesize that H95 could function as molecular switch for prion conversion, and copper bound to this residue may function in protein conformation stabilization. We also propose a cellular model for prion formation in cells expressing the H95Y mutant. Interestingly, our data may establish a platform for rationally designed experiments aimed at elucidating whether the H95Y mutation may cause de novo prion diseases in transgenic mice.

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Books on the topic "Propagative regime":

M, Filippov V. Konvekt͡s︡ii͡a︡ plazmy v subavroralʹnoĭ zone. I͡A︡kutsk: I͡A︡kutskiĭ nauch. t͡s︡entr SO RAN, 1996.

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Vaidya, W. V. An experimental assessment of hysteresis in near-threshold fatigue crack propagation regime of a low alloy ferritic steel under closure-free testing conditions. Geesthacht: GKSS-Forschungszentrum Geesthacht GmbH, 1991.

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United States. National Aeronautics and Space Administration., ed. Investigation of tropical transport with UARS data: Final report : contract no. NAS5-32862. [Bellevue, Wash.]: Northwest Research Associates, 1999.

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Helfont, Samuel. Addressing the Limits of Coercion and Co-optation. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190843311.003.0006.

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This chapter discusses the limits of the regime’s attempts to co-opt religious leaders in Iraq, which resulted in a dearth of trusted religious scholars. Often, religious leaders who cooperated with the regime continued to secretly hold and propagate views that the regime did not like; they were unreliable, and they often subtly resisted the Ba‘thist interpretations of Islam. This occurred most prominently with regard to sectarian views, which the regime wished to suppress, but which religious leaders in official institutions continued to promote. To address the problem, the regime created institutions to create trusted religious leaders. These included the Saddam Institute for Imams and Sermon Givers in 1985 and then the Saddam University for Islamic Studies in 1987. The regime tightly controlled who was accepted to these institutions and what they studied.

Helfont, Samuel. Putting the System to Work. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190843311.003.0012.

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This chapter discusses the way that the regime used its institutions and authoritarian systems to propagate its Ba’thist interpretation of religion. The chapter discusses the differences between Islamism and Ba’thist ideas about Islam. It demonstrates that the latter was interpreted through the lens of Arab nationalism. The rhetoric and symbols that the regime employed were embedded within authoritarian structures that were not always visible to the public. These structures were necessary to police the boundaries of acceptable religious discourse because the Ba’thist interpretation of Islam was not a traditional interpretation of the religion. Therefore, the regime needed to prevent critical discourse on Ba’thist Islam that would expose it as significantly different from the ways in which the religion had traditionally been interpreted in the region. This policing took place not only in mosques but also in the media and in textbooks for schools.

Wang, Bin. Intraseasonal Modulation of the Indian Summer Monsoon. Oxford University Press, 2018. http://dx.doi.org/10.1093/acrefore/9780190228620.013.616.

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The strongest Indian summer monsoon (ISM) on the planet features prolonged clustered spells of wet and dry conditions often lasting for two to three weeks, known as active and break monsoons. The active and break monsoons are attributed to a quasi-periodic intraseasonal oscillation (ISO), which is an extremely important form of the ISM variability bridging weather and climate variation. The ISO over India is part of the ISO in global tropics. The latter is one of the most important meteorological phenomena discovered during the 20th century (Madden & Julian, 1971, 1972). The extreme dry and wet events are regulated by the boreal summer ISO (BSISO). The BSISO over Indian monsoon region consists of northward propagating 30–60 day and westward propagating 10–20 day modes. The “clustering” of synoptic activity was separately modulated by both the 30–60 day and 10–20 day BSISO modes in approximately equal amounts. The clustering is particularly strong when the enhancement effect from both modes acts in concert. The northward propagation of BSISO is primarily originated from the easterly vertical shear (increasing easterly winds with height) of the monsoon flows, which by interacting with the BSISO convective system can generate boundary layer convergence to the north of the convective system that promotes its northward movement. The BSISO-ocean interaction through wind-evaporation feedback and cloud-radiation feedback can also contribute to the northward propagation of BSISO from the equator. The 10–20 day oscillation is primarily produced by convectively coupled Rossby waves modified by the monsoon mean flows. Using coupled general circulation models (GCMs) for ISO prediction is an important advance in subseasonal forecasts. The major modes of ISO over Indian monsoon region are potentially predictable up to 40–45 days as estimated by multiple GCM ensemble hindcast experiments. The current dynamical models’ prediction skills for the large initial amplitude cases are approximately 20–25 days, but the prediction of developing BSISO disturbance is much more difficult than the prediction of the mature BSISO disturbances. This article provides a synthesis of our current knowledge on the observed spatial and temporal structure of the ISO over India and the important physical processes through which the BSISO regulates the ISM active-break cycles and severe weather events. Our present capability and shortcomings in simulating and predicting the monsoon ISO and outstanding issues are also discussed.

Kinderman, Daniel. The Initiative for a New Social-Market Economy and the Transformation of the German Welfare Regime after Unification. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780190676681.003.0008.

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This chapter focuses on how business interests and neoliberal ideas have come together in Germany during the past two decades. It is based on a detailed analysis of the INSM, a large-scale campaign founded and funded by the metal industry employers’ association Gesamtmetall in 2000 to shape public opinion. Since its origination, the INSM has launched a systematic attack on the German welfare state. As part of a business-led public relations campaign, the purpose of the INSM is to propagate market-oriented reforms and influence public opinion and policymaking rather than to develop new economic ideas. Nevertheless, a group of economists associated with the Mont Pèlerin Society have actively supported and campaigned for the INSM. The INSM exposes a serious problem with the academic literature that characterizes Germany as an exemplar of “nonliberal” capitalism: the positions of leading German business officials and economists are fundamentally and unmistakably liberal.

Sorenson, David S. Syria in Ruins. ABC-CLIO, LLC, 2016. http://dx.doi.org/10.5040/9798216021971.

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Syria is home to one of the most brutal and protracted civil wars in history, posing a threat to global stability and enabling the expansion of the Islamic State (sometimes called "ISIS"). This in-depth analysis reveals the beginning, present state, and future of this conflict. The current crises involving ISIS have attracted worldwide attention to the complex politics and cultural panorama of the Middle East, including Syria. Political analyst and author David S. Sorenson discusses the ongoing civil war in Syria from its origins, to its key players, and to its propagation into neighboring countries. In the process, the work delves into Syria's demographics, history, economy, and security to illustrate the civil war's impact on the Middle East and the world. This in-depth analysis covers the Assad regime, ISIS's role in the region, possible outcomes of the conflict, and security implications for the country. Starting with a history of Syria, the work identifies the factors that have contributed to the onset and continuation of the civil war, moves on to an analysis of the outbreak and growth of the war, and points out key factors that fueled its intensity. A look at the Islamic State considers the internationalization of the Syrian civil war, explaining how the addition of many parties outside of Syria have made the war more violent and protracted. The book concludes by considering alternative endings for the conflict and addressing the role of world powers in the conflict and its outcome. Syria is home to one of the most brutal and protracted civil wars in history, posing a threat to global stability and enabling the expansion of the Islamic State (sometimes called "ISIS"). This in-depth analysis reveals the beginning, present state, and future of this conflict. The current crises involving ISIS have attracted worldwide attention to the complex politics and cultural panorama of the Middle East, including Syria. Political analyst and author David S. Sorenson discusses the ongoing civil war in Syria from its origins, to its key players, and to its propagation into neighboring countries. In the process, the work delves into Syria's demographics, history, economy, and security to illustrate the civil war's impact on the Middle East and the world. This in-depth analysis covers the Assad regime, ISIS's role in the region, possible outcomes of the conflict, and security implications for the country. Starting with a history of Syria, the work identifies the factors that have contributed to the onset and continuation of the civil war, moves on to an analysis of the outbreak and growth of the war, and points out key factors that fueled its intensity. A look at the Islamic State considers the internationalization of the Syrian civil war, explaining how the addition of many parties outside of Syria have made the war more violent and protracted. The book concludes by considering alternative endings for the conflict and addressing the role of world powers in the conflict and its outcome.

Helfont, Samuel. Continuity and Change in the Gulf War. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190843311.003.0007.

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This chapter discusses the Ba’thist regime’s use of religion during the Gulf Crisis in 1990 and the Gulf War in 1991. In 1990, Saddam invaded Kuwait and then Saddam again raised eyebrows in 1991 by delivering what became known as his first and second “jihad speeches,” which highlighted long-held Ba’thist ideas about Islam. Saddam was able to integrate the regime’s political instrumentalization of religion into its broader strategies for the war. Those ideas were then echoed throughout Iraq’s religious landscape and in its official and unofficial propaganda during the war. As this chapter shows, the increase in regime’s propagation of religious propaganda during the conflict reflected an increase in its institutional capacity to organize and present its views on religion rather than a shift in ideology away from Ba’thism toward Political Islam.

Dixon, Kingsley. Coastal Plants. CSIRO Publishing, 2011. http://dx.doi.org/10.1071/9780643101753.

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Coastal Plants provides a definitive guide to the 100 most common plants of the Perth coastal region and includes the key species used in coastal restoration. Each species is presented with its Latin name, common name and family, together with its distribution, key diagnostic features, natural history, pollination, uses in restoration and propagation. The description for each species is accompanied by a distribution map and diagnostic photographs of the whole plant, flowers, seeds and fruits. Coastal Plants also contains introductory chapters on the biology and ecology of the coastal plants, their biogeography, and practical approaches to the restoration of coastal dune vegetation.

Book chapters on the topic "Propagative regime":

Fouque, Jean-Pierre, and Josselin Garnier. "On waves in random media in the diffusion-approximation regime." In Wave Propagation in Complex Media, 31–48. New York, NY: Springer New York, 1998. http://dx.doi.org/10.1007/978-1-4612-1678-0_3.

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Savin, Eric. "Diffusive Regime for the High-Frequency Dynamics of Randomly Heterogeneous Plates." In Mathematical and Numerical Aspects of Wave Propagation WAVES 2003, 357–62. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-642-55856-6_57.

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Kaushik, Mrinal. "Sound Wave Propagation in Compressible Fluids and Flow Regimes." In Fundamentals of Gas Dynamics, 109–36. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-9085-3_3.

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Bannov, N. A., V. V. Mitin, and F. T. Vasko. "Multimode Regime of Hot Acoustic Phonon Propagation in Two Dimensional Layers." In Hot Carriers in Semiconductors, 441–43. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0401-2_101.

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Muskens, O. L., and J. I. Dijkhuis. "Propagation and Diffraction of Picosecond Acoustic Wave Packets in the Soliton Regime." In Optical Solitons, 391–406. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/3-540-36141-3_18.

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Meshcheryakov, Yurii. "The Mesoscale Velocity Distribution and Change of Regime of Shock Wave Propagation." In Shock Wave and High Pressure Phenomena, 49–66. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-4530-3_5.

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Wills-Davey, M. J., and B. J. Thompson. "Observations of a Propagating Disturbance in Trace." In Physics of the Solar Corona and Transition Region, 467–83. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-017-3429-5_29.

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Ndou, Eliphas, and Nombulelo Gumata. "Do High Government Debt-to-GDP Regimes Propagate the Adverse Macroeconomic Effects of High Budget Deficit Regimes?" In Fiscal Policy Shocks and Macroeconomic Growth in South Africa, 109–18. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-37755-6_8.

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Dattoli, G., H. Fang, T. Hermsen, and A. Torre. "Theory of FEL Pulse Propagation: The Small Signal Low Gain Long E-Bunch Regime." In Springer Proceedings in Physics, 141–50. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-74088-6_18.

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Puszynski, Jan A. "Recent Advances in Synthesis and Densification of Nanomaterials in Self-Propagating High-Temperature Regime." In Advances in Science and Technology, 994–1004. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/3-908158-01-x.994.

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Conference papers on the topic "Propagative regime":

Ritchie, Burke. "Theory of optical pulse propagation in the region between superfluorescence and amplified spontaneous emission." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/oam.1992.tuz34.

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The coupling of forward and backward propagating waves is studied theoretically in the transition region between superfluorescence (SF) and amplified spontaneous emission (ASE). To accomplish this a computer code has been written that solves Maxwell's equations in time and two spatial dimensions and accounts for counter-propagation, diffraction, and temporal coherence in the Bloch equations. Diffraction is ignored in the present calculations. In the SF regime the coupling is generally weak, as found by others; however, I have found a randomly occurring shot-to-shot coupling that is quite significant in cases where one wave, forward or backward, becomes established from quantum noise first in the amplified rod. In this case the wave that arises second is strongly coupled to the first. In the ASE regime the propagation shows strong forward-backward coupling and the characteristic spatial profile of the inversion that tends to zero at either end and to the small signal value of one in the middle of the amplifier. In the transion region the propagation shows mixed SF and ASE behavior.

Trillo, S., S. Wabnitz, E. M. Wright, and G. I. Stegeman. "Generation and propagation of bright solitonlike pulses in the normal dispersion regime." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/oam.1988.mw4.

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Optical solitons are potentially useful both in future optical communication systems and in optical computing logic gates. As is well known, anomalous dispersion is a necessary condition for the generation and propagation of a bright soliton. We present analytical and numerical results predicting the propagation of bright solitary waves even in the normal dispersion regime. First, we show that when two pulses interact through linear coupling, as in the case of two orthogonal polarization modes in a birefringent fiber, modulational polarization instabilities1 may induce the generation of a train of ultrashort pulses in the visible. We compare the characteristics of these pulses with those obtainable in the anomalous dispersion regime. Another mechanism for the propagation of a bright solitary pulse in the normal dispersion regime is the interaction via cross-phase modulation2 with a fundamental dark soliton, which in turn is allowed to propagate in the anomalous dispersion regime. We discuss the stability of this analytical solution to the coupled nonlinear Schrodinger equations by means of beam propagation simulations. (12 min)

Murdoch, S. G., R. Leonhardt, and J. D. Harvey. "Polarisation Modulation Instability in Weakly Birefringent Fibres." In Nonlinear Guided Waves and Their Applications. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/nlgw.1995.nsab2.

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Modulation instability (MI) is a phenomenon exhibited by waves propagating in nonlinear dispersive media, in which weak amplitude perturbations at different frequencies are subject to gain. In the scalar description of wave propagation in optical fibres governed by the nonlinear Schrödinger equation (NLSE), MI can occur only in the anomalous dispersion regime, and this was the first form of MI to be observed [1]. Soon after this observation, however, it was predicted that the coherent interaction of two different circularly polarised waves of the same frequency propagating in a birefringent fibre would give rise to modulation instability in both the normal and the anomalous dispersion regimes [2,3]. To our knowledge this prediction has not been experimentally verified. Modulation instability has however, been observed in the normal dispersion regime by pumping highly birefringent fibres with intense red or green pulses [4,5]. This form of MI arises from the incoherent interaction of two linearly polarised pulses propagating down the fast and slow axes of the fibre simultaneously. In these highly birefringent fibres, the terms which give rise to the coherent MI can be neglected in view of the large wavevector mismatch between the orthogonal modes. We report here the first observation of "polarisation modulation instability" (PMI). This instability possesses different characteristics depending on whether the pump is on the fast or slow axis.

Sun, Jason, and Paul Jukes. "Finite Element Analysis of Clamp-On Buckle Arrestor for Pipe-in-Pipe Flowlines by Reel-Lay Installation." In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57276.

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Development of deep water oil reservoirs are undertaken in the Gulf of Mexico (GoM) where the flowlines are installed in the water depths in excess of 3,050m (10,000ft). Deepwater external pressure becomes so significant that it makes local buckling or accidental collapse propagate along the pipeline. Such propagation will not stop until it reaches a region where the external pressure falls below the propagating pressure or where the pipe wall is strengthened. Field data indicates that once a buckle happens, the flowline could collapse many kilometers instantly. It concludes that buckle propagation could cause substantial economical impact if left uncontrolled. For pipe-in-pipe (PIP) flowline, due to lack of pressure differential, the outer pipe becomes a fragile component in terms of buckle propagation. One way to prevent the propagation of local buckling or collapse is to utilize the buckle arrestors of various types. Clamp-on buckle arrestor is so far the best choice for the flowlines to be installed by the Reel-Lay method. The objective of this paper is to present the results of a finite element (FE) study, to reveal the phenomena of collapsing/propagating of the pipe-in-pipe flowline, and to investigate the effectiveness of Clamp-on buckle arrestor for deep water flowlines. Sensitivities of key design parameters are explored with the purpose of guiding detail mechanical design of the clamp-on buckle arrestor.

Trillo, S., and S. Wabnitz. "Modulational Polarization Instability in Birefringent Fibers." In Optical Bistability. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/obi.1988.fb.6.

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A wave propagating in a nonlinear dispersive medium may be unstable with respect to weak modulations.1 This modulational instability (MI) has been recently observed in optical fibers in the anomalous dispersion regime of propagation.2,3

Kitahara, R., J. Ishi, and K. Ema. "Soliton Propagation in Two-Photon Resonant Region." In Nonlinear Optics: Materials, Fundamentals and Applications. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/nlo.1996.nme.35.

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The stability of soliton propagation in nonresonant region has been studied extensively. The temporal and spatial evolution of pulses in such region can be analyzed with the nonlinear Schrödinger equation (NSE). The effects of the third-order dispersion term can be analyzed in the frame of NSE, however the dispersion of nonlinearity is usually ignored except for some extreme cases such as shock term.1) When we consider the propagation of ultrashort pulse or the propagation in resonant region, the effects of nonlinear dispersion reveal themselves remarkably. Nevertheless, the dispersion of nonlinearity have not been fully explored. In this paper, we examine the pulse propagation characteristics with dispersive nonlinearity using nonlinear wave equation in frequency domain. We show that, when pulses propagate at the two-photon resonant region, the effects of the third-order dispersion is compensated by the dispersive nonlinearity and solitonlike propagation of femtosecond pulses can be achieved.

Pushkarev, Andrei, and Vladimir Zakharov. "Nonlinear Laser-Like Ocean Waves Radiation Orthogonal to the Wind." In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-19357.

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Abstract We study deep water ocean wind-driven waves in strait, with wind directed orthogonally to the shore, through exact Hassel-mann equation. The strait has “dissipative” shores, there is no any reflection from the coast lines. We show that the wave turbulence evolution can be split in time into two different regimes. During the first regime, the waves propagate along the wind, and the wind-driven sea can be described by the self-similar solutions of Hasselmann equation. The second regime starts later in time, after significant enough wave energy accumulation at the down-wind boundary. Since this moment the ensemble of waves propagating against the wind starts its formation. Also, orthogonal to the wind waves, propagating along the strait, start to appear. The wave system eventually reaches asymptotic stationary state in time, consisting of two co-existing states: the first, self-similar wave ensemble, propagating with the wind, and the second – quasi-monochromatic waves, propagating almost orthogonally to the wind direction, and tending to slant against the wind at the angle of 15° closer to the wave turbulence origination shore line. Those “secondary waves” appear only due to intensive nonlinear wave-wave interaction. The total wave energy exceeds its “expected value” approximately by the factor of two, with respect to estimated in the absence of the shores. It is expected that in the reflective shores presence this amplification will grow essentially. We propose to call this “secondary” laser-like Nonlinear Ocean Waves Amplification mechanism by the acronym NOWA.

Talebkeikhah, M., S. Momeni, G. Lu, and B. Lecampion. "Experimental Investigation of Hydraulic Fracture Closure in a Porous Sandstone." In International Geomechanics Symposium. ARMA, 2022. http://dx.doi.org/10.56952/igs-2022-175.

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Abstract Depending on the type of fracture propagation regime when the injection stops, the closure of the fracture may occur exactly after the injection ceases, in the case where the fracturing process is dominated by fracture energy, or the fracture propagate for a while due to the elastic energy stored in the rock, when fluid viscous dissipation dominates. In any cases, fluid losses in the surrounding porous media ultimately stops fracture growth and the fracture closes (on the proppant pack in practice). Some recent theoretical solutions have been reported for the recession and closure of a hydraulic fracture in the absence of proppant. These solutions are relevant in the context of micro hydraulic fracturing tests for in-situ stress determination. In this work, we report a laboratory hydraulic fracture experiments performed in sandstones with the aim to study experimentally fracture closure. In our experimental set-up, an extensive passive acoustic monitoring is performed and provide un-precedented spatio-temporal evolution of fracture development and closure. Introduction and Motivation Hydraulic fracturing is one of the methods for stimulating oil and gas wells. In this method, high-pressure fluid injection causes tensile fractures, which leads to an increase in rock permeability and conductivity, and as a result, increases oil and gas production (Madyarova and Detournay, 2003). Investigating the behavior of fracture propagation in hydraulic fracturing operations is one of the topics that researchers are working on. Fracture propagation in rocks follows different regimes. When the energy is dissipated to overcome the toughness of the rock to form new fracture surfaces, the regime is toughness dominated and when the energy is dissipated in the flow of viscous fluid in the fracture, it is viscosity dominated (Lecampion et al, 2017). In addition, when this fracture is created in permeable and porous rocks, in which there is fluid loss into the rock, these regimes are converted to toughness-leak off dominated and viscosity-leak off dominated regimes respectively (Detournay, 2016).

Behbahani-Nejad, M., and N. C. Perkins. "Forced Wave Propagation in Elastic Cables With Small Curvature." In ASME 1995 Design Engineering Technical Conferences collocated with the ASME 1995 15th International Computers in Engineering Conference and the ASME 1995 9th Annual Engineering Database Symposium. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/detc1995-0548.

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Abstract This study presents an investigation of the coupled longitudinal-transverse waves that propagate along an elastic cable. The coupling considered derives from the equilibrium curvature (sag) of the cable. A mathematical model is presented that describes the three-dimensional nonlinear response of a long elastic cable. An asymptotic form of this model is derived for the linear response of cables having small equilibrium curvature. Linear in-plane response is described by coupled longitudinal-transverse partial differential equations of motion, which are comprehensively evaluated herein. The spectral relation governing propagating waves is derived using transform methods. In the spectral relation, three qualitatively distinct frequency regimes exist that are separated by two cut-off frequencies. This relation is employed in deriving a Green’s function which is then used to construct solutions for in-plane response under arbitrarily distributed harmonic excitation. Analysis of forced response reveals the existence of two types of periodic waves which propagate through the cable, one characterizing extension-compressive deformations (rod-type) and the other characterizing transverse deformations (string-type). These waves may propagate or attenuate depending on wave frequency. The propagation and attenuation of both wave types are highlighted through solutions for an infinite cable subjected to a concentrated harmonic excitation source.

Birenis, Domas, Yuhei Ogawa, Hisao Matsunaga, Osamu Takakuwa, Junichiro Yamabe, Øystein Prytz, and Annett Thøgersen. "Hydrogen-Assisted Fatigue Crack Propagation in a Commercially Pure BCC Iron." In ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84783.

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Hydrogen effect on fatigue performance of commercially pure BCC iron has been studied with a combination of various electron microscopy techniques. The fatigue crack growth (FCG) in gaseous hydrogen was found to consist of two regimes corresponding to a slightly accelerated regime at relatively low stress intensity factor range, ΔK, (Stage I) and the highly accelerated regime at relatively high ΔK (Stage II). These regimes were manifested by the intergranular and quasicleavage types of fractures respectively. Scanning electron microscopy (SEM) observations demonstrated an increase in plastic deformation around the crack wake in the Stage I, but considerably lower amount of plasticity around the crack path in the Stage II. Transmission electron microscopy (TEM) results identified dislocation cell structure immediately beneath the fracture surface of the Stage I sample, and dislocation tangles in the Stage II sample corresponding to fracture at high and low plastic strain amplitudes respectively.

Reports on the topic "Propagative regime":

Kamrath, Matthew, Vladimir Ostashev, D. Wilson, Michael White, Carl Hart, and Anthony Finn. Vertical and slanted sound propagation in the near-ground atmosphere : amplitude and phase fluctuations. Engineer Research and Development Center (U.S.), May 2021. http://dx.doi.org/10.21079/11681/40680.

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Sound propagation along vertical and slanted paths through the near-ground atmosphere impacts detection and localization of low-altitude sound sources, such as small unmanned aerial vehicles, from ground-based microphone arrays. This article experimentally investigates the amplitude and phase fluctuations of acoustic signals propagating along such paths. The experiment involved nine microphones on three horizontal booms mounted at different heights to a 135-m meteorological tower at the National Wind Technology Center (Boulder, CO). A ground-based loudspeaker was placed at the base of the tower for vertical propagation or 56m from the base of the tower for slanted propagation. Phasor scatterplots qualitatively characterize the amplitude and phase fluctuations of the received signals during different meteorological regimes. The measurements are also compared to a theory describing the log-amplitude and phase variances based on the spectrum of shear and buoyancy driven turbulence near the ground. Generally, the theory correctly predicts the measured log-amplitude variances, which are affected primarily by small-scale, isotropic turbulent eddies. However, the theory overpredicts the measured phase variances, which are affected primarily by large-scale, anisotropic, buoyantly driven eddies. Ground blocking of these large eddies likely explains the overprediction.

Apel, John R. Generation, Propagation, and Dissipation of Internal Waves in Continental Shelf Regimes. Fort Belvoir, VA: Defense Technical Information Center, September 1997. http://dx.doi.org/10.21236/ada629379.

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Wilmont, Martyn, Greg Van Boven, and Tom Jack. GRI-96-0452_1 Stress Corrosion Cracking Under Field Simulated Conditions I. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), November 1997. http://dx.doi.org/10.55274/r0011963.

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Electrochemical measurements have been performed on polished and mill scaled steel samples. The solutions investigated have included carbonate bicarbonate mixtures of varying pH as well as solutions of neutral pH such as NS4. Results indicate that the mechanism of corrosion associated with the carbonate bicarbonate environments involves passive film formation. No such passivation is observed for solutions associated with neutral pH SCC. Electrochemical corrosion rates measured on polished steel specimens exposed to NS4 solutions in the pH range 5 to 6.8 were in the region of 5 x 10e-1 to 1 x 10e-2 mm/s. However, rates obtained on mill scaled surfaces went much lower and in the region of 5 x 10e-10 mm/s. Field determined crack propagation rates are estimated to be in the region of 2 x 10e-8 mm/s. Whilst the laboratory determined corrosion rates are lower than the field propagation rate it should be remembered that the laboratory rates were obtained on unstressed specimens. The application of load would be expected to increase the corrosion rate and may indicate that stress focused dissolution process may be sufficient to explain the propagation of neutral pH stress corrosion cracks. However, as hydrogen evolution is the most likely cathodic reaction involved in the mechanism of neutral pH SCC the role of hydrogen in the crack propagation mechanism may also be important.

Wilson, D., Vladimir Ostashev, Michael Shaw, Michael Muhlestein, John Weatherly, Michelle Swearingen, and Sarah McComas. Infrasound propagation in the Arctic. Engineer Research and Development Center (U.S.), December 2021. http://dx.doi.org/10.21079/11681/42683.

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This report summarizes results of the basic research project “Infrasound Propagation in the Arctic.” The scientific objective of this project was to provide a baseline understanding of the characteristic horizontal propagation distances, frequency dependencies, and conditions leading to enhanced propagation of infrasound in the Arctic region. The approach emphasized theory and numerical modeling as an initial step toward improving understanding of the basic phenomenology, and thus lay the foundation for productive experiments in the future. The modeling approach combined mesoscale numerical weather forecasts from the Polar Weather Research and Forecasting model with advanced acoustic propagation calculations. The project produced significant advances with regard to parabolic equation modeling of sound propagation in a windy atmosphere. For the polar low, interesting interactions with the stratosphere were found, which could possibly be used to provide early warning of strong stratospheric warming events (i.e., the polar vortex). The katabatic wind resulted in a very strong low-level duct, which, when combined with a highly reflective icy ground surface, leads to efficient long-distance propagation. This information is useful in devising strategies for positioning sensors to monitor environmental phenomena and human activities.

Inan, Umran S. Subionospheric VLF/LF Propagation in the Presence of Transient and Localized Perturbations of Nighttime D-region. Fort Belvoir, VA: Defense Technical Information Center, March 1991. http://dx.doi.org/10.21236/ada250871.

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Wilson, D., Michael Shaw, Vladimir Ostashev, Michael Muhlestein, Ross Alter, Michelle Swearingen, and Sarah McComas. Numerical modeling of mesoscale infrasound propagation in the Arctic. Engineer Research and Development Center (U.S.), October 2022. http://dx.doi.org/10.21079/11681/45788.

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The impacts of characteristic weather events and seasonal patterns on infrasound propagation in the Arctic region are simulated numerically. The methodology utilizes wide-angle parabolic equation methods for a windy atmosphere with inputs provided by radiosonde observations and a high-resolution reanalysis of Arctic weather. The calculations involve horizontal distances up to 200 km for which interactions with the troposphere and lower stratosphere dominate. Among the events examined are two sudden stratospheric warmings, which are found to weaken upward refraction by temperature gradients while creating strongly asymmetric refraction from disturbances to the circumpolar winds. Also examined are polar low events, which are found to enhance negative temperature gradients in the troposphere and thus lead to strong upward refraction. Smaller-scale and topographically driven phenomena, such as low-level jets, katabatic winds, and surface-based temperature inversions, are found to create frequent surface-based ducting out to 100 km. The simulations suggest that horizontal variations in the atmospheric profiles, in response to changing topography and surface property transitions, such as ice boundaries, play an important role in the propagation.

Cohen, Yuval, Christopher A. Cullis, and Uri Lavi. Molecular Analyses of Soma-clonal Variation in Date Palm and Banana for Early Identification and Control of Off-types Generation. United States Department of Agriculture, October 2010. http://dx.doi.org/10.32747/2010.7592124.bard.

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Date palm (Phoenix dactylifera L.) is the major fruit tree grown in arid areas in the Middle East and North Africa. In the last century, dates were introduced to new regions including the USA. Date palms are traditionally propagated through offshoots. Expansion of modern date palm groves led to the development of Tissue Culture propagation methods that generate a large number of homogenous plants, have no seasonal effect on plant source and provide tools to fight the expansion of date pests and diseases. The disadvantage of this procedure is the occurrence of off-type trees which differ from the original cultivar. In the present project we focused on two of the most common date palm off-types: (1) trees with reduced fruit setting, in which most of the flowers turn into three-carpel parthenocarpic fruits. In a severe form, multi-carpel flowers and fruitlets (with up to six or eight carpels instead of the normal three-carpel flowers) are also formed. (2) dwarf trees, having fewer and shorter leaves, very short trunk and are not bearing fruits at their expected age, compared to the normal trees. Similar off-types occur in other crop species propagated by tissue culture, like banana (mainly dwarf plants) or oil palm (with a common 'Mantled' phenotype with reduced fruit setting and occurrence of supernumerary carpels). Some off-types can only be detected several years after planting in the fields. Therefore, efficient methods for prevention of the generation of off-types, as well as methods for their detection and early removal, are required for date palms, as well as for other tissue culture propagated crops. This research is aimed at the understanding of the mechanisms by which off-types are generated, and developing markers for their early identification. Several molecular and genomic approaches were applied. Using Methylation Sensitive AFLP and bisulfite sequencing, we detected changes in DNA methylation patterns occurring in off-types. We isolated and compared the sequence and expression of candidate genes, genes related to vegetative growth and dwarfism and genes related to flower development. While no sequence variation were detected, changes in gene expression, associated with the severity of the "fruit set" phenotype were detected in two genes - PdDEF (Ortholog of rice SPW1, and AP3 B type MADS box gene), and PdDIF (a defensin gene, highly homologous to the oil palm gene EGAD). We applied transcriptomic analyses, using high throughput sequencing, to identify genes differentially expressed in the "palm heart" (the apical meristem and the region of embryonic leaves) of dwarf vs. normal trees. Among the differentially expressed genes we identified genes related to hormonal biosynthesis, perception and regulation, genes related to cell expansion, and genes related to DNA methylation. Using Representation Difference Analyses, we detected changes in the genomes of off-type trees, mainly chloroplast-derived sequences that were incorporated in the nuclear genome and sequences of transposable elements. Sequences previously identified as differing between normal and off-type trees of oil palms or banana, successfully identified variation among date palm off-types, suggesting that these represent highly labile regions of monocot genomes. The data indicate that the date palm genome, similarly to genomes of other monocot crops as oil palm and banana, is quite unstable when cells pass through a cycle of tissue culture and regeneration. Changes in DNA sequences, translocation of DNA fragments and alteration of methylation patterns occur. Consequently, patterns of gene expression are changed, resulting in abnormal phenotypes. The data can be useful for future development of tools for early identification of off-type as well as for better understanding the phenomenon of somaclonal variation during propagation in vitro.

Rabethge, Nico, and Kurt-Georg Ciesinger. KI in der Schmutzwäsche-Sortierung. Kompetenzzentrum Arbeitswelt.Plus, January 2023. http://dx.doi.org/10.55594/wgct6835.

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Im Leuchtturmprojekt KI in der Schmutzwäschesortierung beschäftigen wir uns mit der Entwicklung eines humanzentrierten KI-gesteuerten Identifikationsmoduls zur Sortie-rung von Wäschestücken nach Waschkategorien. Diese Entwicklung soll in der Praxis dazu beitragen, dass die hochbelastende und potenziell gesundheitsgefährdende manuelle Sortierung von Schmutzwäsche nicht mehr wie im bisherigen Umfang von Menschen geleistet werden muss. Eine KI-gestützte Identifikation, verbunden mit einem Handhabungsgerät könnte die Sortierung in weiten Teilen autonom übernehmen. Neben der optimalen Unterstützung von Mitarbeitenden sind die Erklärung und Transferierbarkeit der KI, sowie die Entwicklung eines Schulungsprogramms, um Akzeptanz sowie Verständnis bei den Nutzer:innen zu verstärken, Forschungsschwerpunkte des Projekts. Es soll eine Mensch-Maschine-Interaktion entwickelt werden, die es Mitarbeitenden ermöglicht die KI selbst nachzutrainieren und zu überwachen. Hierdurch ergeben sich neue, zukunftsfähige Arbeitsfelder für die Beschäftigten in Industriewäschereien. Zuerst wurde anhand des Versuchsstandes ein initialer Datensatz aus 9405 Bildern erstellt. Zu jedem der Bilder existieren Informationen über die Farbe, den Typ und zumeist auch über die Kontaminierung, die Schäden und das Material. Anschließend wurden neuronale Netze sowohl zur Extraktion der Region des Wäschestücks als auch zu der Klassifikation der Waschkategorien trainiert, d.h. die Netze lernten zu erkennen, was zum Wäschestück gehört und was nicht und Wäschestücke, Farben und Ver-schmutzungen zu erkennen. Durch einen am aktiven Lernen orientierten Prozess konnten dabei 2091 Segmentierungen automatisch erstellt werden, d.h. ohne menschliche Eingabe der Annotationen. Für die Optimierung dieser neuronalen Netze wurden zusätzlich auch noch vortrainierte Netze nachtrainiert, welches allgemein als Transfer Learning (transferiertes Lernen) bezeichnet wird. Hinsichtlich des Aktiven Lernens wurde der CEAL-Algorithmus erläutert und damit die Sicherheit der Netze bei der Klassifikation bestimmt. Für visuelle Erklärungen wurde Layerwise Relevance Propagation umgesetzt. Wir haben erste Erkenntnisse bzgl. der Sortierung erlangen können und für einige Kate-gorien bereits sehr zufriedenstellende Ergebnisse erlangt. Durch die beiden neuronalen Netze konnten gute Erkennungsgenauigkeiten für alle Kategorien, insbesondere der Farbe, erzielt werden. Hierbei muss jedoch beachtet werden, dass die Datensätze und dementsprechend vor allem die Validierungsdatensätze klein sind. Es ist unbedingt notwendig, den Datensatz zu vergrößern. Dabei sollte höchste Priorität sein, die Aufnahme und Annotation in einer Wäscherei zu verlagern, um möglichst automatisiert und möglichst schnell Daten aufnehmen und annotieren zu können.

Academic literature on the topic 'Propagative regime'

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Journal articles on the topic "Propagative regime":

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Books on the topic "Propagative regime":

Book chapters on the topic "Propagative regime":

Conference papers on the topic "Propagative regime":

Reports on the topic "Propagative regime":