335 research outputs found
Quasi full-disk maps of solar horizontal velocities using SDO/HMI data
For the first time, the motion of granules (solar plasma on the surface on
scales larger than 2.5 Mm) has been followed over the entire visible surface of
the Sun, using SDO/HMI white-light data.
Horizontal velocity fields are derived from image correlation tracking using
a new version of the coherent structure tracking algorithm.The spatial and
temporal resolutions of the horizontal velocity map are 2.5 Mm and 30 min
respectively .
From this reconstruction, using the multi-resolution analysis, one can obtain
to the velocity field at different scales with its derivatives such as the
horizontal divergence or the vertical component of the vorticity. The intrinsic
error on the velocity is ~0.25 km/s for a time sequence of 30 minutes and a
mesh size of 2.5 Mm.This is acceptable compared to the granule velocities,
which range between 0.3 km/s and 1.8 km/s. A high correlation between
velocities computed from Hinode and SDO/HMI has been found (85%). From the data
we derive the power spectrum of the supergranulation horizontal velocity field,
the solar differential rotation, and the meridional velocity.Comment: 8 pages, 11 figures, accepted in Astronomy and Astrophysic
From ANT to Material agency: a design and science research workshop
International audienceThis paper studies a design workshop that investigates complex collaboration between fundamental physics and design. Our research focuses on how students create original artefacts that bridge the gap between disciplines that have very little in common. Our goal is to study the micro-evolutions of their projects. Elaborating first on Actor Network Theory (Latour, 1996; 2005) we study how students' projects evolved over time and through a diversity of inputs and media. Throughout this longitudinal study, we use then a semiotic and pragmatic approach to observe three "aesthetical formations": translation, composition, and stabilization. These formations suggest that the question of material agency developed in the field of archeology and cognitive science (Knappett & Malafouris, 2008) need to be considered in the design field (Renon, 2016) to explain metamorphoses from the brief to the final realizations
Assessment of numerical methods for fully resolved simulations of particle-laden turbulent flows
This work was granted access to the HPC resources of CALMIP and the National Center for Atmospheric Researchs (NCAR) supercomputing centers. P. Costa acknowledges the funding from the Portuguese Foundation for Science and Technology under grant no. SFRH/BD/85501/2012. L.-P. Wang acknowledges the funding from the U.S. National Science Foundation (NSF) under grants CBET-1706130.Peer reviewedPostprin
Thermodynamic modeling of ternary liquid-liquid systems with forming immiscibility islands
Prediction of liquid-liquid equilibria for polyethylene glycol based aqueous two-phase system by ASOG and UNIFAC method
Multilocal programming and applications
Preprint versionMultilocal programming aims to identify all local minimizers of unconstrained
or constrained nonlinear optimization problems. The multilocal programming
theory relies on global optimization strategies combined with simple ideas
that are inspired in deflection or stretching techniques to avoid convergence to the
already detected local minimizers. The most used methods to solve this type of problems
are based on stochastic procedures and a population of solutions. In general,
population-based methods are computationally expensive but rather reliable in identifying
all local solutions. In this chapter, a review on recent techniques for multilocal
programming is presented. Some real-world multilocal programming problems
based on chemical engineering process design applications are described.Fundação para a CiĂȘncia e a Tecnologia (FCT
Orientational Effects and Random Mixing in 1-Alkanol + Alkanone Mixtures
1-Alkanol + alkanone systems have been investigated through the data analysis of molar excess functions,
enthalpies, isobaric heat capacities, volumes and entropies, and using the Flory model and the formalism of the concentrationconcentration
structure factor (SCC(0)). The enthalpy of the hydroxyl-carbonyl interactions has been evaluated. These
interactions are stronger in mixtures with shorter alcohols (methanol-1-butanol) and 2-propanone or 2-butanone. However,
effects related to the self-association of alcohols and to solvation between unlike molecules are of minor importance when
compared with those which arise from dipolar interactions. Physical interactions are more relevant in mixtures with longer
1-alkanols. The studied systems are characterized by large structural effects. The variation of the molar excess enthalpy with the
alcohol size along systems with a given ketone or with the alkanone size in solutions with a given alcohol are discussed in terms of
the different contributions to this excess function. Mixtures with methanol show rather large orientational effects. The random
mixing hypothesis is attained to a large extent for mixtures with 1-alkanols â methanol and 2-alkanones. Steric effects and
cyclization lead to stronger orientational effects in mixtures with 3-pentanone, 4-heptanone, or cyclohexanone. The increase of
temperature weakens orientational effects. Results from SCC(0) calculations show that homocoordination is predominant and
support conclusions obtained from the Flory model.Ministerio de Ciencia e InnovacioÌn, under Project
FIS2010-1695
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