A unified approach to compute foliations, inertial manifolds, and tracking initial conditions

Several algorithms are presented for the accurate computation of the leaves in the foliation of an ODE near a hyperbolic fixed point. They are variations of a contraction mapping method in [25] to compute inertial manifolds, which represents a particular leaf in the unstable foliation. Such a mapping is combined with one for the leaf in the stable foliation to compute the tracking initial condition for a given solution. The algorithms are demonstrated on the Kuramoto-Sivashinsky equation

Scattering of Bunched Fractionally Charged Quasiparticles

The charge of fractionally charged quasiparticles, proposed by Laughlin to explain the fractional quantum Hall effect (FQHE), was recently verified by measurements. Charge q=e/3 and e/5 (e is the electron charge), at filling factors nu=1/3 and 2/5, respectively, were measured. Here we report the unexpected bunching of fractional charges, induced by an extremely weak backscattering potential at exceptionally low electron temperatures (T<10 mK) - deduced from shot noise measurements. Backscattered charges q=nu e, specifically, q=e/3, q=2e/5, and q<3e/7, in the respective filling factors, were measured. For the same settings but at an only slightly higher electron temperature, the measured backscattered charges were q=e/3, q=e/5, and q=e/7. In other words, bunching of backscattered quasiparticles is taking place at sufficiently low temperatures. Moreover, the backscattered current exhibited distinct temperature dependence that was correlated to the backscattered charge and the filling factor. This observation suggests the existence of 'low' and 'high' temperature backscattering states, each with its characteristic charge and characteristic energy.Comment: 4 pages, 3 figure

Effects of turbulence mixing, variable properties, and vaporization on spray droplet combustion

Combustion of liquid fuels in the form of spray droplets is simulated numerically. Various vaporization models are examined as to their performance in finite element calculations involving a turbulent flow field. The Eulerian coordinate for the gas and Lagrangian coordinate for the liquid spray droplets are coupled through source terms being updated in the equations of continuity, momentum, and energy. The k-epsilon and modified eddy breakup models are used for simulating turbulent spray combustion flow field. Numerical results for the droplet trajectories, droplet heating, recirculation characteristics, and effects of evaporation models are evaluated. It is also shown that the finite element method is advantageous in dealing with complex geometries, complex boundary conditions, adaptive unstructured grids

Bajos niveles de variación isoenzimática en las poblaciones sureñas del arbusto endémico de Corea Sophora koreensis (Fabaceae): implicaciones para su conservación

We investigated allozyme variation of the rare shrub Sophora koreensis in Yanggu County (South Korea), at the southern margin of the species range. To gain insights into ecological processes at the landscape level, we studied two or three populations from four localities (in total, 10 populations) in a range of ca. 6 km. We found low levels of within-population genetic variation (%P = 13.6, A = 1.14, and He = 0.026) and a moderate degree of among-population genetic differentiation (FST = 0.203). The analysis of molecular variance (AMOVA) revealed a substantially higher percentage of variation among populations within localities (17%) than among localities (5%). There was no significant relationship between pairwise genetic divergence and logarithm of pairwise geographic distance (r = 0.032, P = 0.842). These results suggest limited gene flow between populations within localities, while indicating that the optimal strategy for the preservation of the genetic variation of S. koreensis is to conserve as many populations as possible.Se investigó la variación isoenzimática del arbusto raro Sophora koreensis en el condado de Yanggu (Corea del Sur), en el extremo sur de su área de distribución. Para obtener información sobre los procesos ecológicos a nivel del paisaje, se estudiaron dos o tres poblaciones para cada una de las cuatro localidades (en total, 10 poblaciones) en un radio de unos 6 km. Se encontraron bajos niveles de variación genética intra-poblacional (%P = 13,6, A = 1,14 y He = 0,026) y un grado moderado de diferenciación genética entre poblaciones (FST = 0,203). El análisis de la varianza molecular (AMOVA) reveló un porcentaje sustancialmente mayor de variación entre poblaciones dentro cada una de las localidades (17%) que entre localidades (5%). No hubo una relación significativa entre la divergencia genética y el logaritmo de la distancia geográfica entre pares de poblaciones (r = 0,032, P = 0,842). Estos resultados sugieren un flujo genético limitado entre poblaciones dentro de las localidades, además de indicar que la mejor estrategia para la preservación de la diversidad genética de S. koreensis es la conservación del máximo número de poblaciones posible

A mathematical simulation model of the CH-47B helicopter, volume 1

A nonlinear simulation model of the CH-47B helicopter was adapted for use in the NASA Ames Research Center (ARC) simulation facility. The model represents the specific configuration of the ARC variable stability CH-47B helicopter and will be used in ground simulation research and to expedite and verify flight experiment design. Modeling of the helicopter uses a total force approach in six rigid body degrees of freedom. Rotor dynamics are simulated using the Wheatlely-Bailey equations including steady-state flapping dynamics. Also included in the model is the option for simulation of external suspension, slung-load equations of motion

CFD code evaluation

The task carried out under this research grant covers research on accuracy and efficiency of computational fluid dynamic (CFD) stategies, error estimates for convective terms, and antidiffusion. These basic studies are considered important in evaluating available CFD codes which will be the main activities for the next year