Analytical approach to sorting in periodic and random potentials - Gleeson, James P.; Sancho, Jose Maria; Lacasta Palacio, Ana María; Lindenberg, K.
There has been a recent revolution in the ability to manipulate micrometer-sized objects on surfaces patterned by traps or obstacles of controllable configurations and shapes. One application of this technology is to separate particles driven across such a surface by an external force according
to some particle characteristic such as size or index of refraction. The surface features cause the trajectories of particles driven across the surface to deviate from the direction of the force by an amount that depends on the particular characteristic, thus leading to sorting. While models of this
behavior have provided a good understanding of these observations, the...
El fuego en la web - Romero Castro, Aldo Humberto; Lopez Moreno, Sinhue; Lacasta Palacio, Ana María
Dispersionless transport in a washboard potential - Lindenberg, K.; Sancho, Jose Maria; Lacasta Palacio, Ana María; Sokolov, Igor M.
We study and characterize a new dynamical regime of underdamped particles in a tilted washboard potential. We find that for small friction in a finite range of forces the particles move essentially nondispersively, that is, coherently, over long intervals of time. The associated distribution of the
particle positions moves at an essentially constant velocity and is far from Gaussian-like. This new regime is complementary to, and entirely different from, well-known nonlinear response and large dispersion regimes observed for other values of the external force.
Characterization of the performance of an injector for the controlled generation of microbubbles - Arias Calderón, Santiago; González Cinca, Ricardo; Ruiz, Xavier; Ramírez de la Piscina Millán, Laureano; Casademunt, Jaume
We perform a characterization of a recently reported microbubble injector in conditions relevant to microgravity. Injection
of bubbles is based on the generation of a slug flow in a capillary T-junction, whose operation is robust to changes in the
gravity level. We address questions regarding the performance under different working regimes. In particular, we focus on
the regimes found within a large range of gas and liquid injection flow rates. The injection performance is characterized
by measuring bubble generation frequency. We propose curves obtained empirically for the behavior of generation
frequency and crossover between regimes.
Experimental study of a microchannel bubble injector for microgravity applications - Arias Calderón, Santiago; Ruiz, Xavier; Casademunt, Jaume; Ramírez de la Piscina Millán, Laureano; González Cinca, Ricardo
We perform a quantitative characterization
of a microbubble injector in conditions relevant to
microgravity. The injector pregenerates a slug flow by
using a capillary T-junction, whose operation is robust
to changes in gravity level. We address questions
regarding the performance under different injection
conditions. In particular we focus on the variation of
both gas and liquid flow rates. The injection performance
is characterized by measuring bubble injection
frequency and bubble sizes. We obtain two distinct
working regimes of the injector and identify the optimal
performance as the crossover region between them.
Propiedades físicas y mecánicas de los agregados reciclados de concreto - Gómez Soberón, José Manuel Vicente; Agulló Fité, Luís; Vázquez Ramonich, Enric
Las propiedades a largo plazo, como la contracción y fluencia, de los concretos reciclados(CR) presentan algunas variaciones con los concretos usuales. Dichas variaciones son interpretadas por las diferencias de densidad, porosidad y absorción de los agregados reciclados procedentes de concreto (ARC), dada su constitución de carácter parcial.
En este trabajo se presenta el análisis experimental de especimenes de CR con reemplazo de agregados naturales por ARC. Se proporcionan y discuten las propiedades de los agregados empleados; así como tópicos de CR, tales como, compresión simple, tensión indirecta, módulo de elasticidad, contracción y fluencia (básicas y por secado). Los especimenes de prueba...
Structural evolution of metallic glasses during annealing through in-situ Synchrotron X-ray diffract - Pineda Soler, Eloi; Boneu, Francesc; Bruna Escuer, Pere; Pradell Cara, Trinitat; Labrador, Ana; Crespo Artiaga, Daniel
In this work we study the structural evolution of Al and Fe based metallic glass
compositions. The samples were obtained as ribbons by melt-spinning, their glass stability and
crystallization were analyzed by calorimetry and dilatometry, structural changes were followed
by in-situ synchrotron X-ray diffraction during annealing throughout glass transition and
crystallization. The synchrotron results are compared with calorimetric and dilatometric
measurements and the structural changes occurred during annealing are determined and
described for each alloy.
Fragility and glass-forming ability of the Ca-Mg-Cu system - Pineda Soler, Eloi; Zhang, Yi; Greer, A. L.
Elastic moduli of the glass and fragility of the corresponding supercooled liquid were found to be correlated in recently published results. In the
present work, compositions within the Ca–Mg–Cu system are used to study the relationships between liquid fragility, glass-forming ability and
elastic properties. The correlation between liquid fragility and elastic properties already observed for glasses in general is found to hold in this
particular system. More extensive work should be done in order to obtain conclusive results. However, if such a correlation turns out to be general
in metallic systems, it will be a powerful criterion in choosing candidate compositions for new bulk...
Temporal evolution of the domain structure in a Poisson-Voronoi transformation - Pineda Soler, Eloi; Crespo Artiaga, Daniel
The temporal evolution of the domain size and free boundary
distributions is calculated for a Poisson–Voronoi transformation. In this kind
of transformation a set of randomly distributed domain seeds start growing
simultaneously, all with equal isotropic growth rate, occupying the original
untransformed space. At the end of the transformation, all the space is occupied
and the final configuration is the well-known Poisson–Voronoi tessellation.
In this work, the temporal evolution of the domain structure in a twodimensional
transformation is obtained by means of a calculation method
presented recently (Pineda et al 2007 Phys. Rev. E 75 040107(R)). The method
is based on the differentiation of the domains through their number...
Higher order colored noise effects in multivariable systems. - Ramírez de la Piscina Millán, Laureano; Sancho, Jose Maria
We extend the partial resummation technique of Fokker-Planck terms for multivariable stochastic differential equations with colored noise. As an example, a model system of a Brownian particle with colored noise is studied. We prove that the asymmetric behavior found in analog simulations is due to higher-order terms which are left out in that technique. On the contrary, the systematic τ-expansion approach can explain the analog results.
Analysis of turbulence in fog episodes - Terradellas, Enric; Ferreres Soler, Enriqueta; Soler, M. R.
Many processes interact in a complex and highly non-linear way during the life cycle of fog, the turbulent transport being among them. Observations and analysis of urbulence are, then, fundamental to our understanding of the physical mechanisms involved with fog formation, evolution and dissipation. Data gathered by fast-response sonic anemometers are processed using wavelet methods in order to estimate turbulence parameters such as kinetic energy or fluxes during the successive stages of fog evolution.