1,054 research outputs found
Optimization of blade profiles for the Wells turbine
No full textA Wells turbine, when coupled with an oscillating water column, allows the generation of power from the energy in waves on the surface of the ocean. In the present work, a tabu search is used to control the process of optimising the blade profile in the Wells turbine for greater performance, by maximising the torque coefficient. A free form deformation method is used as an efficient means of manipulating the blade profile and computational fluid dynamics in OpenFOAM are used to assess each profile in both two and three dimensions. Investigations into both the flow coefficient at which the optimization is performed and the number of control variables in the free form deformation tool are performed before optimisations are done on a two-dimensional blade at the hub and tip solidities. This results in increases to the torque coefficient of 34% and 32% at the tip and hub solidities, respectively. These results are then applied to the three-dimensional turbine, giving a 14% increase in the torque coefficient. The results are assessed and an improved method of optimising the blade in two dimensions is proposed
The waiting-time phenomena of gravity currents in fluids and non linear diffusion
No full textLa presente investigación de Tesis trata sobre el fenómeno de tiempo de espera en corrientes de gravedad en fluidos y difusión no lineal. Muchos fenómenos se describen mediante la ecuación de difusión no lineal unidimensional (EDNL): h1 = δx(hᵐδxh) (1) en donde los subíndices t y x indican derivadas parciales respecto del tiempo y del espacio, respectivamente. Entre ellos se pueden citar: (a) flujos en acuíferos no confinados en la aproximación de Dupuit-Forchheimer (Polubarinova-Kochina 1962, Eagleson 1970, Peletier l981, m=l), (b) flujos de gases en medios porosos (Muskat 1937, Gilding y Peletier l977a, l977b, Vázquez 1983, m=γ), (c) conducción térmica en plasmas (Zel’dovich y Raizer 1966, m=5/2) (d) conducción del calor por radiación en gases multiplemente ionizados (Zel’dovich y Raizer 1966, Pert 1977, m=4,5-5,5). (e) conducción del calor por radiación en gases completamente ionizados (Marshak 1958, Zel’dovich y Raizer 1966, Larsen y Pomraning 1980, m=l3/2), (f) corrientes viscogravitatorias (CVG, m=3). Las CVG son un tipo particular de corrientes de gravedad en líquidos, e interesan en las ciencias naturales y por sus aplicaciones a la tecnología y al medio ambiente (Simpson, 1982, Huppeit, 1986). Son flujos que se derraman sobre una superficie plana horizontal y rígida en el régimen en que los esfuerzos viscosos balancean la gravedad (bajo número de Reynolds y efectos de capilaridad despreciables) descriptos por la aproximación de lubricación (Buckmaster 1977, Huppert 1982, Gratton y Minotti 1990). Por la facilidad con que se las puede estudiar en el laboratorio, son una herramienta muy útil para el estudio de la difusión no lineal. Una característica de la difusión no lineal es la presencia de frentes que separan dominios donde h>0 de otros en donde h=0 (recordar la velocidad finita de propagación de una onda térmica fuerte); otra característica es la existencia de soluciones con tiempo de espera (STE), cuyo frente queda inmóvil durante un lapso finito tw, mientras ocurren cambios detrás de él (Aronson 1970, Kamin 1980, Knerr 1977, Lacey et al. 1982, Kath y Cohen 1982, Lacey 1983, Aronson et al. 1983, 1985, Vázquez 1984, Thomas et al. 1991, Gratton et al. 1992, Marino et al. 1995). Las soluciones autosemejantes de la ecuación (1) fueron estudiadas extensamente en el caso unidimensional, en el que dependen de una única variable ξ=x/tδ, donde x representa a una coordenada cartesiana (simetría plana) o a una radial (simetría axial). Su interes radica en que se obtienen fácilmente y que representan el comportamiento asintótico intermedio de muchos problemas no autosemejantes (Barenblatt 1952, Barenblatt y Zel’dovich 1957, Pattle 1959, Pen 1977, Grundy 1979, etc.). También se conocen bien las CVG autosemejantes (Buckmaster, 1977, Huppen, 1982, Gratton y Minotti, 1990, Maxworhy 1982, 1983, Huppert 1982, etc.). Reseñas sobre las propiedades de la ecuación (1) y de las STE se encuentran en Gratton (1991a) y Gratton et al. (1992). Una reseña sobre la autosemejanza, sus aplicaciones y las corrientes de gravedad en fluidos, incluyendo las CVG, puede encontrarse en Gratton (1991b). En esta investigación de Tesis Doctoral se investigan STE para CVG planas con condiciones iniciales del tipo h c xp. El proceso comienza en t=—t(...); inicialmente el frente está en x=0 y hǂ0 para 0<x<xo, siendo ho su valor característico: el frente arranca en t=0 (h(xo—tw)ǂ0)), la condición de contorno en xo corresponde a una pared ideal). Las soluciones se obtuvieron numéricamente con gran precisión, para lo cual se desarrolló un código ad hoc. El trabajo de investigación se dirigió a aclarar los siguientes puntos: (a) La relación entre condiciones iniciales y tiempo de espera y otras propiedades de las soluciones. No hay fórmulas teóricas para tw (salvo para un único caso: p=2/m), pero sí cotas superiores e inferiores (Kath y Cohen 1982, Lacey et al. 1982, Vázquez 1984, Aronson et al. 1985). Con condiciones iniciales del tipo h c xp, Kath y Cohen (1982) mostraron que, para m<<l, hay un tiempo de espera no nulo si p≥2/m, y que si p>2/m aparece un corner layer en la solución (un CL, es un pequeño intervalo Δx en el que hx varía fuertemente). Vázquez (1984) extendió este resultado para todo m>0. (b) La asintótica de las STE cerca del frente y para tiempos próximos al momento del arranque (ǀxǀ<<xo, ǀtǀ<<tw ǀhǀ<<ho). En ese dominio ninguno de los parámetros característicos de las condiciones iniciales puede intervenir en la solución, por lo cual se espera que sea autosemejante de II Especie (Barenblatt y Zel’dovich 1972, Barenblatt 1979, Aronson y Vázquez 1994). Se verifica esta conjetura y se encuentra la relación δ=δ(p). Previamente al estudio numérico se investigan las soluciones autosemejantes relevantes, que se agrupan en dos familias de acuerdo con δ (Gratton y Vigo l994a): las soluciones LOT (Lacey et al. 1982) y las soluciones A. Las soluciones LOT existen para todo δ>l y son de tres clases: si l<δ<l3/l0 (clase L) presentan una sucesión infinita de CL cuyo punto de acumulación es el frente; si δ>l3/l0 (clases E y N) no hay CL. La nomenclatura proviene del comportamiento de la singularidad en el plano de fase que les da origen (el ciclo límite L o el punto B, quien de acuerdo al valor de δ, es un punto Espiral o Nodo). Las soluciones A tienen δ≤1, y representan la evolución del corner layer fuerte que está llegando al frente; el caso δ=1 es la solución de onda viajera (0V, ver Gratton y Minotti 1990). Las soluciones numéricas muestran que si p<2/3 el frente arranca de inmediato y si p>2/3 se obtienen soluciones con tiempo de espera con un CL móvil, de acuerdo con la teoría. El CL se refuerza (Δx se reduce y aumenta la variación de hx) mientras avanza hacia el frente que espera, y cuando lo alcanza, éste se pone en movimiento. Se estudia en detalle el movimiento del CL y del frente y otras propiedades de las soluciones. Se determina tw(p) y se compara con las cotas teóricas, viendo que en muchos casos estas no son buenos estimadores de tw. La asintótica de las STE muestra un comportamiento sorprendente. En primer lugar sólo las soluciones clase L y la OV son relevantes. Tan sólo la parte de las soluciones L que está detrás del primer CL de la sucesión representa la asintótica de las soluciones numéricas, y lo hace en un dominio que está detrás del corner layer, y para un intervalo de tiempo que excluye el entorno del arranque (se observa un solo CL, porque cerca del frente la solución verdadera converge demasiado lentamente a la solución L). En cambio la asintótica en el entorno del CL y para tiempos próximos al arranque (e incluyéndolo) está descripta por la 0V (δ=1), de forma tal que el movimiento del CL empalma con continuidad con el del frente, luego del arranque. Los flujos viscogravitatorios son un privilegio para el investigador puesto que constituyen un caso modelo altamente viable para su implementación experimental a escala de laboratorio; en ese sentido la verificación experimental de la teoría fue realizada en colaboración con el grupo del Instituto de Física de Arroyo Seco (IFAS), de la Universidad Nacional del Centro de la Provincia de Buenos Aires (UNCPBA), Tandil, dirigido por el Profesor R. Gratton, en donde se realizaron experimentos de derrames de aceites de siliconas con perfiles iniciales en forma de cuña (correspondientes a p=l), que presentan tiempo de espera (Marino et al. 1996). Se presenta una reseña de estos resultados experimentales y una comparación con algunos de los resultados obtenidos en esta Tesis.The present Thesis Investigation address with the waiting-time viscous gravity currents phenomena and non linear diffusion. A wide range of phenomena are described by the one-dimensional non linear diffusion equation (NLDE): h1 = δx(hᵐδxh) (l) where the t and x subscripts indicate partial time and spatial derivatives, respectively. Among them, we can mention: (a) unconfined groundwater flows, in the Dupuit Forchheimer approximation (Polubarinova-Kochina 1962, Eagleson 1970, Peletier 1981, m=l), (b) gas flow through porous media (Muskat 1937 Gilding y Peletier l977a, l977b, Vázquez 1983, m=γ), (c) thermal conduction in plasmas (Zel’dovich y Raizer 1966, m=5/2) (d) thermal conduction by radiation in multiply ionized gas (Zel’dovich y Raizer 1966, Pert 1977, m=4,5-5,5), (e) thermal conduction by radiation in a fully ionized gas (Marshak 1958, Zel’dovich y Raizer 1966, Larsen y Pomraning 1980, m=l3/2), (f) viscous gravity currents (VGC, m=3). The VGC are a special case of viscous currents in liquids, and are of particular interest in technology applications and natural and environmental sciences, (Simpson, 1982, Huppen, 1986). VGC refers to flows over a horizontal rigid plane surface in the regime where viscous forces balance gravity (low Reynolds number and capillary effects are negligibles), and are described by the lubrication approximation. (Buckmaster 1977, Huppert 1982, Gratton y Minotti 1990). They are a useful tool for the study of non linear diffusion, because they are inexpensive and simple to set up in the laboratory. A characteristic of the non linear diffusion is the presence of fronts that divide domains where h>0 from others where h=0 (remember the finite propagation velocity of the strong thermal wave); another characteristic is the existence of waiting-time solutions (WTS), which have a front that remains motionless during a finite time tw, while some changes occur behind it. (Aronson 1970, Kamin 1980, Knerr 1977, Lacey et al. 1982, Kath y Cohen 1982, Lacey 1983, Aronson et al. 1983, 1985, Vázquez 1984, Thomas et al. 1991, Gratton et al. 1992, Marino er al. 1995). Self similar solutions of equation (l) were studied extensively in the one dimensional case in which they depend on a single variable ξ=x/tδ, where x is a Cartesian coordinate (plane symmetry) or a radial coordinate (axial symmetry). They are interesting because can be easily constructed and represent the intermediate asymptotic behavior of a wide range of non self similar problems. (Barenblatt l952, Barenblatt y Zel’dovich 1957, Pattle 1959, Pert 1977, Grundy 1979, etc.). The self-similar VGC are well known (Buckmaster, 1977, Huppert, 1982, Gratton y Minotti, 1990, Maxworthy 1982, 1983, Huppert 1982, etc.). Reviews about the properties of equation (1) and WTS can be found in Gratton (1991a) and Gratton et al, (1992). Other reviews about self-similarity, its aplications, and the gravity currents in fluids, including VGC, can be found in Gratton (l99lb). In this PHD Thesis Research, we investigate WTS for plane VGC with initial conditions of the type h c xp. The process begins at t=—tw, initially the front is at x=0 y hǂ0 for 0<x<xo, where ho is a characteristic value: the front starts to move at t=0 (h(xo-tw)ǂ0), the boundary condition at xo corresponds to an idealized wall). The solutions are obtained numerically with high precision using a scheme developed ad hoc. The work was focalized on the solution to the following points: (a) the relation between initial conditions and waiting-time and other properties of the solutions. There are no analytical formulae to determine tw (there is a only case, p=2/m), but higher and lower bounds are available (Kath y Cohen 1982, Lacey et al. 1982, Vázquez 1984, Aronson et al. 1985). For initial conditions of the type h c xP. Kath y Cohen (1982) proved that, for m<<l, there exists a non vanishing waiting time if p≥2/m, and if p>2/m, a corner layer (CL) developed in the solution (a CL, is a small interval Δx where hx suffers strong variations). Vazquez (1984) extended this result for all m>0. (b) The asymptotic regime of WTS near the front and close to the startup time (ǀxǀ<<xo, ǀtǀ<<tw ǀhǀ<<ho). In this domain, no characteristic parameters of the initial conditions can enter the solution. It is for this reason that we expect the solution to be self-similar of the Second Kind (Barenblatt y Zel’dovich 1972, Barenblatt 1979, Aronson y Vázquez 1994). We verify this conjecture and found the δ=δ(p) relation. Prior to the numerical study we investigate the relevant WTS, that can be grouped in two families, according to the value of δ (Gratton y Vigo l994a): the LOT solutions (Lacey et al. 1982) and the A solutions. The LOT solutions exist for all δ>l and are of three classes: when 1<δ<l3/10 (L class), they present an infinite series of CL with an accumulation point in the front; if δ>l3/10 (clases E y N) there is no CL at all. The nomenclature comes from the behavior of the singularity in the phase plane, a limit cycle L or a spiral or nodal (according to the value of δ ) point B. The A solutions have δ≤1, and represent the evolution of a strong corner layer that is arriving to the front; the δ=1 case corresponds to the travelling wave (TW, see Gratton y Minotti, 1990). The numerical solutions show that if p<2/3 the front starts to move inmediately and that if p>2/3, we obtain waiting-time solutions with a moving CL, according to the theory. The CL reinforces (Δx decrease and hx increase) while it moves toward the front, and when it reaches it, the front it begins to move. We study in detail the movement of the CL and of the front and another properties of the solutions. We determine tw(p) and compare it with the theoretical bounds, and observe that in many cases, these are not a good estimator of tw. The asymptotic regime of the WTS shows a surprising behavior. First, only the L and TW classes are relevant to the problem. Only the part of the L solutions that is behind the first CL of the series represents the asymptotic of the numerical solutions, and it does so in a domain that is behind the CL, for a time interval that excludes the startup, (only one CL can be observed because near the front, the real solution converges too slowly to the L solution). On the other hand, the asymptotic in a region around the CL for times close to the startup time (including it), is described by the TW (δ=1), in such a way that CL joins smoothly with the front after startup. The viscous gravity flows are a privilege for the researchers, because they constitute a model case of wide experimental implementation in the laboratory; in this sense, the experimental check of the theory was made in conjunction with the group of the Instituto de Física de Arroyo Seco (IFAS), from the Universidad Nacional del Centro de la Provincia de Buenos Aires (UNCPBA), Tandil, directed by Professor R. Gratton. They make experiments on the spreading of silicone oils with initial wedge-like profiles (corresponding to p=l), that presents waiting-time behavior (Marino et al. 1996). We show a review of these experimental results and a comparation with some of the results obtained in this Thesis.Fil:Vigo, Claudio Lionel Martín. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Abscisic acid-induced microheterogeneity in phospholipid vesicle: a fluorescence study.
No full textChanges in the thermal behavior of DMPC (dimyristoyl-r-phosphatidylcholine) and an equimolar mixture of DMPC and DMPE (dimyristoyl-L-phosphatidylethanolamine) induced by the plant hormone abscisic acid (ABA) have been investigated using fluorescent probes. The fluorescence decay of the hydrophobic probe 1,6-diphenyl-1,3,5-hexatriene (DPH) in these vesicles has been measured using frequency-domain fluorometry, and has been analyzed using both models of discrete exponential components and continuous lifetime distributions. In the DMPC vesicles, using the distributional approach, higher center and width values were observed in the presence of abscisic acid (ABA), indicating a decrease in the dielectric constant of the lipid phase that we attribute to a decrease in the water concentration within the bilayer. Moreover, the presence of ABA in the liposomes increased the phospholipid phase transition temperature. The addition of ABA to the DMPC/DMPE mixture strongly increased the microheterogeneity of the system as reported by the FWHM (full-width at half-maximum) of the distributional approach
A different view on light element anti-correlations in globular clusters: Fluorine abundances in NGC 6656 (M22)
No full textObserved chemical (anti)correlations in the light elements C, N, O, Na, Mg, and Al among globular cluster (GC) stars are presently recognised as the signature of self-pollution from previous generations of stars. This defines the multiple population scenario (MPS). Since fluorine is involved in the complete CNO cycle, determining its abundance in GCs provides new and complementary clues regarding the nature of these previous generations. In fact, along with the Na-O and Mg-Al anti-correlations, the MPS also predicts an anti-correlation between F and Na and a positive correlation between F and O. Furthermore, theoretical models suggest that low-mass (≲5Mȯ) asymptotic giant branch (AGB) stars are F producers (and are also responsible for C+N+O and s-process element variations). We present our results on near-infrared CRIRES spectroscopic observations of six giant stars in the metal-poor GC NGC 6656 (M22): we aim at inferring the F content and its (possible) variation in this GC, which exhibits a rather peculiar abundance pattern, with variations in both light (C, N, O, Na, Mg, Al) and heavy (Fe-peak and s-process) elements. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.SCOPUS: cp.pinfo:eu-repo/semantics/publishe
Accurate mass ratio and heating effects in the dual-line millisecond binary pulsar in NGC 6397
No full textBy means of high-resolution spectra, we have measured radial velocities of the companion (hereafter COM J1740-5340) to the eclipsing millisecond pulsar PSR J1740-5340 in the galactic globular cluster NGC 6397. The radial velocity curve fully confirms that COM J1740-5340 is orbiting the pulsar, and this enables us to derive the most accurate mass ratio (M-PSR/M-COM = 5.85 +/- 0.13) for any nonrelativistic binary system containing a neutron star. Assuming a pulsar mass in the range 1.3-1.9 M-., the mass of COM J1740-5340 spans the interval 0.22-0.32 M-., the inclination of the system is constrained within, and the Roche lobe 56degrees greater than or similar to i greater than or similar to 47degrees and the Roche lobe radius is r(RL) similar to1.5-1.7 R-.. A preliminary chemical abundance analysis confirms that COM J1740-5340 has a metallicity compatible with that measured for other stars in this metal-poor globular, but the unexpected detection of strong He I absorption lines implies the existence of regions at K, which are significantly warmer T > 10,000 than the rest of the star. The intensity of this line correlates with the orbital phase, suggesting the presence of a region on the companion surface, heated by the millisecond pulsar flux
Fast Rotating Blue Stragglers in the Globular Cluster M4
No full textWe have used high-resolution spectra obtained with the spectrograph FLAMES at the European Southern Observatory Very Large Telescope to determine the kinematical properties and the abundance patterns of 20 blue straggler stars (BSSs) in the globular cluster (GC) M4. We found that ~40% of the measured BSSs are fast rotators (with rotational velocities >50 km s-1). This is the largest frequency of rapidly rotating BSSs ever detected in a GC. In addition, at odds with what has been found in 47 Tucanae, no evidence of carbon and/or oxygen depletion has been revealed in the sample of 11 BSSs for which we were able to measure the abundances. This could be due to either low statistics, or a different BSS formation process acting in M4.
Based on observations collected at the ESO-VLT under program 081.D-0356. Also based on observations collected at the ESO-MPI Telescope under program 69.D-0582, and with the NASA/ESA HST, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555
Discovery of Carbon/Oxygen-depleted Blue Straggler Stars in 47 Tucanae: The Chemical Signature of a Mass Transfer Formation Process
No full textWe use high-resolution spectra obtained with the ESO Very Large Telescope to measure surface abundance patterns of 43 blue straggler stars (BSSs) in 47 Tuc. We discovered that a subpopulation of BSSs shows a significant depletion of carbon and oxygen with respect to the dominant population. This evidence would suggest the presence of CNO burning products on the BSS surface coming from a deeply peeled parent star, as expected in the case of a mass transfer process. This is the first detection of a chemical signature clearly pointing to a specific BSS formation process in a globular cluster.
Based on observations collected at the ESO-VLT (Cerro Paranal, Chile) under program 072.D-0337
Mitochondrial DNA reveals regional and interregional importance of the central Mediterranean African shelf for loggerhead sea turtles (Caretta caretta).
No full textThe wide north African continental shelf in the central Mediterranean is known to be one of the few important areas in the basin for loggerhead turtles in the neritic stage. In order to assess the origin of these turtles, sequences of the mtDna control region were obtained from 70 turtles caught by bottom trawlers in the area, and compared with known sequences from turtles from Mediterranean and atlantic nesting sites. Five haplotypes were identified (Haplotype diversity = 0.262; nucleotide diversity = 5.4×10-3). Specific haplotypes indicate contributions from distant rookeries such as Turkey and the Atlantic, which shows that Atlantic turtles entering the Mediterranean while in the oceanic phase use at least one Mediterranean continental shelf as a neritic foraging ground. A new haplotype and another one previously found only in foraging areas, highlight the genetic information gaps for nesting sites, which undermine powerful mixed stock analyses. Despite these limitations, the results reveal the regional importance of the study area as a neritic foraging ground for turtles that are probably from most of the Mediterranean nesting aggregates. Therefore, reducing turtle mortality resulting from the high fishing effort in the area should be regarded as key for Mediterranean turtle conservation and is also possibly important for atlantic populations
Análisis de una interfase plasma-gas neutro
No full textSe ha elaborado un modelo que permite estudiarel estado estacionario de una interfase plasma-gas neutropara una geometría plana. Esta región se encuentra comprendidaentre un plasma totalmente ionizado, cuya densidad (> 10^17 cm̄³) y temperatura son datos, y un gas frío totalmenteneutro, de temperatura conocida. Ha sido empleada unadescripción macroscópica de cinco fluidos: electrones, ioneslivianos que provienen del plasma, iones pesados originadosen la ionización de átomos del gas frio y los neutroscorrespondientes. Para una situación colisional, en la cualla ionización por impacto electrónico y la recombinación detres cuerpos son los mecanismos dominantes del balance departiculas, el modelo incluye la existencia de un campo eléctricoproducido por el efecto de separación de cargas. Sehan estudiado numéricamente las situaciones correspondientesa plasmas de deuterio con densidades entre 10^17 - 10^19 cm̄³y temperaturas de 5 — 50 eV, con oxigeno, o silicio, a temperaturade 0.17 eV, como gas neutro. Tres constantes físicasrelacionadas con los flujos de particulas, F, con el balancede presiones, P, y con el flujo de energía total dela región en estudio, Q, caracterizan al modelo e imponenvínculos entre las variables físicas, condicionadas ademaspor las otras hipótesis adoptadas. También ha sido calculadala importancia relativa de cada uno de los términos que contribuyenal balance total de energia. Este conocimiento sobrela interfase fue aplicado al estudio de la difusión deun campo magnético a través de la misma.Fil: Fuentes, Néstor Osvaldo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Análisis de una interfase plasma-gas neutro
No full textSe ha elaborado un modelo que permite estudiarel estado estacionario de una interfase plasma-gas neutropara una geometría plana. Esta región se encuentra comprendidaentre un plasma totalmente ionizado, cuya densidad (> 10^17 cm̄³) y temperatura son datos, y un gas frío totalmenteneutro, de temperatura conocida. Ha sido empleada unadescripción macroscópica de cinco fluidos: electrones, ioneslivianos que provienen del plasma, iones pesados originadosen la ionización de átomos del gas frio y los neutroscorrespondientes. Para una situación colisional, en la cualla ionización por impacto electrónico y la recombinación detres cuerpos son los mecanismos dominantes del balance departiculas, el modelo incluye la existencia de un campo eléctricoproducido por el efecto de separación de cargas. Sehan estudiado numéricamente las situaciones correspondientesa plasmas de deuterio con densidades entre 10^17 - 10^19 cm̄³y temperaturas de 5 — 50 eV, con oxigeno, o silicio, a temperaturade 0.17 eV, como gas neutro. Tres constantes físicasrelacionadas con los flujos de particulas, F, con el balancede presiones, P, y con el flujo de energía total dela región en estudio, Q, caracterizan al modelo e imponenvínculos entre las variables físicas, condicionadas ademaspor las otras hipótesis adoptadas. También ha sido calculadala importancia relativa de cada uno de los términos que contribuyenal balance total de energia. Este conocimiento sobrela interfase fue aplicado al estudio de la difusión deun campo magnético a través de la misma.Fil: Fuentes, Néstor Osvaldo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
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