The motion of a deformable drop in a second-order fluid

The cross-stream migration of a deformable drop in a unidirectional shear flow of a second-order fluid is considered. Expressions for the particle velocity due to the separate effects of deformation and viscoelastic rheology are obtained. The direction and magnitude of migration are calculated for the particular cases of Poiseuille flow and simple shear flow and compared with experimental data

Treatment of bimodality in proficiency test of pH in bioethanol matrix

The pH value in bioethanol is a quality control parameter related to its acidity and to the corrosiveness of vehicle engines when it is used as fuel. In order to verify the comparability and reliability of the measurement of pH in bioethanol matrix among some experienced chemical laboratories, reference material (RM) of bioethanol developed by Inmetro - the Brazilian National Metrology Institute - was used in a proficiency testing (PT) scheme. There was a difference of more than one unit in the value of the pH measured due to the type of internal filling electrolytic solutions (potassium chloride, KCl or lithium chloride, LiCl) from the commercial pH combination electrodes used by the participant laboratories. Therefore, bimodal distribution has occurred from the data of this PT scheme. This work aims to present the possibilities that a PT scheme provider can use to overcome the bimodality problem. Data from the PT of pH in bioethanol were treated by two different statistical approaches: kernel density model and the mixture of distributions. Application of these statistical treatments improved the initial diagnoses of PT provider, by solving bimodality problem and contributing for a better performance evaluation in measuring pH of bioethanol.Comment: 20 pages, 6 figures, Accepted for publication in Accreditation and Quality Assurance (ACQUAL

An Investigation of the KFK_{F}-type Lorentz-Symmetry Breaking Gauge Models in N=1N=1-Supersymmetric Scenario

In this work, we present two possible venues to accomodate the $K_{F}$-type Lorentz-symmetry violating Electrodynamics in an $N=1$-supersymmetric framework. A chiral and a vector superfield are chosen to describe the background that signals Lorentz-symmetry breaking. In each case, the $\ K_{\mu \nu \kappa \lambda }$-tensor is expressed in terms of the components of the background superfield that we choose to describe the breaking. We also present in detail the actions with all fermionic partners of the background that determine $\ K_{\mu \nu \kappa \lambda }$.Comment: 10 page

Nonlinear dynamics of drops and bubbles and chaotic phenomena

Nonlinear phenomena associated with the dynamics of free drops and bubbles are investigated analytically, numerically and experimentally. Although newly developed levitation and measurement techniques have been implemented, the full experimental validation of theoretical predictions has been hindered by interfering artifacts associated with levitation in the Earth gravitational field. The low gravity environment of orbital space flight has been shown to provide a more quiescent environment which can be utilized to better match the idealized theoretical conditions. The research effort described in this paper is a closely coupled collaboration between predictive and guiding theoretical activities and a unique experimental program involving the ultrasonic and electrostatic levitation of single droplets and bubbles. The goal is to develop and to validate methods based on nonlinear dynamics for the understanding of the large amplitude oscillatory response of single drops and bubbles to both isotropic and asymmetric pressure stimuli. The first specific area on interest has been the resonant coupling between volume and shape oscillatory modes isolated gas or vapor bubbles in a liquid host. The result of multiple time-scale asymptotic treatment, combined with domain perturbation and bifurcation methods, has been the prediction of resonant and near-resonant coupling between volume and shape modes leading to stable as well as chaotic oscillations. Experimental investigations of the large amplitude shape oscillation modes of centimeter-size single bubbles trapped in water at 1 G and under reduced hydrostatic pressure, have suggested the possibility of a low gravity experiment to study the direct coupling between these low frequency shape modes and the volume pulsation, sound-radiating mode. The second subject of interest has involved numerical modeling, using the boundary integral method, of the large amplitude shape oscillations of charged and uncharged drops in the presence of a static or time-varying electric field. Theoretically predicted non linearity in the resonant frequency of the fundamental quadrupole mode has been verified by the accompanying experimental studies. Additional phenomena such as hysteresis in the frequency response of ultrasoncially levitated droplets in the presence of a time varying electric field, and mode coupling in the oscillations of ultrasonically modulated droplets, have also been uncovered. One of the results of this ground-based research has been the identification and characterization of phenomena strictly associated with the influence of the gravitational field. This has also allowed us to identify the specific requirements for potential microgravity investigations yielding new information not obtainable on Earth

Slip behavior in liquid films on surfaces of patterned wettability: Comparison between continuum and molecular dynamics simulations

We investigate the behavior of the slip length in Newtonian liquids subject to planar shear bounded by substrates with mixed boundary conditions. The upper wall, consisting of a homogenous surface of finite or vanishing slip, moves at a constant speed parallel to a lower stationary wall, whose surface is patterned with an array of stripes representing alternating regions of no-shear and finite or no-slip. Velocity fields and effective slip lengths are computed both from molecular dynamics (MD) simulations and solution of the Stokes equation for flow configurations either parallel or perpendicular to the stripes. Excellent agreement between the hydrodynamic and MD results is obtained when the normalized width of the slip regions, $a/\sigma \gtrsim {\cal O}(10)$, where $\sigma$ is the (fluid) molecular diameter characterizing the Lennard-Jones interaction. In this regime, the effective slip length increases monotonically with $a/\sigma$ to a saturation value. For $a/\sigma \lesssim {\cal O}(10)$ and transverse flow configurations, the non-uniform interaction potential at the lower wall constitutes a rough surface whose molecular scale corrugations strongly reduce the effective slip length below the hydrodynamic results. The translational symmetry for longitudinal flow eliminates the influence of molecular scale roughness; however, the reduced molecular ordering above the wetting regions of finite slip for small values of $a/\sigma$ increases the value of the effective slip length far above the hydrodynamic predictions. The strong inverse correlation between the effective slip length and the liquid structure factor representative of the first fluid layer near the patterned wall illustrates the influence of molecular ordering effects on slip in non-inertial flows.Comment: 12 pages, 10 figures Web reference added for animations: http://www.egr.msu.edu/~priezjev/bubble/bubble.htm

NUMERICAL STUDY OF OIL SPILL IN THE PATOS LAGOON ESTUARY REGION

The consumption pattern of the world population is based on petroleum derivatives, which despite contributing to the improvement of the quality of life, has negative aspects, mainly in the environmental scope. The number of oil spills in water slide has increased significantly in recent years. Considering the complexity of the marine environment, the present work aims to apply a identification system of the dynamics and dispersion of oil, using the numerical modeling in the region of Franceses Bridge, near to Patos Lagoon-RS, Brazil. The study of hypothetical events of oil leakage in the region is of fundamental importance, since the Riograndense Petroleum Refinery is located inside of the Patos Lagoon estuary. A data structure of atmospheric and oceanic circulation was organized and inserted in the coupling between the hydrodynamic module Telemac-3D and the ECOS oil model, during the period between 2010 and 2013. The coupling of these models provided satisfactory results, requiring a level of computational effort favorable to obtaining of results capable of giving technical and scientific support to studies such as those of environmental impacts and contingency plans

Estimativas de parâmetros genéticos na variedade de milho BR 5028 - São Francisco no Nordeste brasileiro.

A variedade de milho BR 5028 - Sao Francisco submetida a diversos ciclos de selecao entre e dentro de progenies de meios-irmaos no Nordeste brasileiro, tem demonstrado possuir grandes potencial em responder a selecao com vistas ao aumento da produtividade de graos, com a continuidade do programa de melhoramento. Por essa razao, novos ciclos de selecao entre e dentro de progenies de meios-irmaos foram praticados na variedade BR 5028, no periodo de 1996 a 1998, nos municipios de Neopolis, Umbauba e N. Sra das Dores, localizados no Estado em Sergipe e Cruz das Almas, no Estado da Bahia, visando a obtencao de material mais produtivo que o atual, e mais adaptavel as condicoes edafoclimaticas da regiao. As 196 progenies de cada ciclo foram avaliadas em latice simples 14 x 14, com duas repeticoes, efetuando-se as recombinacoes dentro do mesmo ano agricola, de modo a se obter uma geracao por ano. As magnitudes dos parametros geneticos mostraram que a variedade BR 5028 - Sao Francisco possui alta variabilidade genetica, a qual fornece perspectiva de aumentos subsequente de producao por selecao, o que, juntamente com o bom rendimento apresentado, e a sua precocidade, faz dessa cultivar alternativa importante para a regiao. A magnitude da interacao progenies x locais evidenciou a importancia de se avaliar as progenies em mais de um local, para melhorar a eficiencia do processo seletivo e obter estimativas mais consistentes dos componentes de variancia