oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 73 )

2019 ( 785 )

2018 ( 890 )

2017 ( 823 )

Custom range...

Search Results: 1 - 10 of 513121 matches for " José A. Cuminato "
All listed articles are free for downloading (OA Articles)
Page 1 /513121
Display every page Item
Theoretical Results of One Class of Multiderivative Methods through Order Stars
Vanessa A. Botta,Messias Meneguette,José A. Cuminato,Sean McKee
Progress in Applied Mathematics , 2011,
Abstract: Order stars are applied to Brown (K,L) methods. They are displayed pictorially for a selection of methods and are used to provide succinct proofs of existing results. Asymptotic results concerning their stability are also presented. Key Words: Brown (K,L) Methods; Stability; Characteristic Polynomials; Order Stars
Surface Tension Implementation for Gensmac2d
Castelo Filho Antonio,Mangiavacchi Norberto,Tomé Murilo F.,Cuminato José A.
Journal of the Brazilian Society of Mechanical Sciences , 2001,
Abstract: In the present work we describe a method which allows the incorporation of surface tension into the GENSMAC2D code. This is achieved on two scales. First on the scale of a cell, the surface tension effects are incorporated into the free surface boundary conditions through the computation of the capillary pressure. The required curvature is estimated by fitting a least square circle to the free surface using the tracking particles in the cell and in its close neighbors. On a sub-cell scale, short wavelength perturbations are filtered out using a local 4-point stencil which is mass conservative. An efficient implementation is obtained through a dual representation of the cell data, using both a matrix representation, for ease at identifying neighbouring cells, and also a tree data structure, which permits the representation of specific groups of cells with additional information pertaining to that group. The resulting code is shown to be robust, and to produce accurate results when compared with exact solutions of selected fluid dynamic problems involving surface tension.
Surface Tension Implementation for Gensmac2d
Castelo Filho, Antonio;Mangiavacchi, Norberto;Tomé, Murilo F.;Cuminato, José A.;Fortuna, Armando O.;Oliveira, Juliana de;Ferreira, Valdemir G.;McKee, Sean;
Journal of the Brazilian Society of Mechanical Sciences , 2001, DOI: 10.1590/S0100-73862001000400013
Abstract: in the present work we describe a method which allows the incorporation of surface tension into the gensmac2d code. this is achieved on two scales. first on the scale of a cell, the surface tension effects are incorporated into the free surface boundary conditions through the computation of the capillary pressure. the required curvature is estimated by fitting a least square circle to the free surface using the tracking particles in the cell and in its close neighbors. on a sub-cell scale, short wavelength perturbations are filtered out using a local 4-point stencil which is mass conservative. an efficient implementation is obtained through a dual representation of the cell data, using both a matrix representation, for ease at identifying neighbouring cells, and also a tree data structure, which permits the representation of specific groups of cells with additional information pertaining to that group. the resulting code is shown to be robust, and to produce accurate results when compared with exact solutions of selected fluid dynamic problems involving surface tension.
Incompressible Turbulent Flow Simulation Using the - Model and Upwind Schemes
V. G. Ferreira,A. C. Brandi,F. A. Kurokawa,P. Seleghim Jr.,A. Castelo,J. A. Cuminato
Mathematical Problems in Engineering , 2007, DOI: 10.1155/2007/12741
Abstract: In the computation of turbulent flows via turbulence modeling, the treatment of the convective terms is a key issue. In the present work, we present a numerical technique for simulating two-dimensional incompressible turbulent flows. In particular, the performance of the high Reynolds κ-ɛ model and a new high-order upwind scheme (adaptative QUICKEST by Kaibara et al. (2005)) is assessed for 2D confined and free-surface incompressible turbulent flows. The model equations are solved with the fractional-step projection method in primitive variables. Solutions are obtained by using an adaptation of the front tracking GENSMAC (Tomé and McKee (1994)) methodology for calculating fluid flows at high Reynolds numbers. The calculations are performed by using the 2D version of the Freeflow simulation system (Castello et al. (2000)). A specific way of implementing wall functions is also tested and assessed. The numerical procedure is tested by solving three fluid flow problems, namely, turbulent flow over a backward-facing step, turbulent boundary layer over a flat plate under zero-pressure gradients, and a turbulent free jet impinging onto a flat surface. The numerical method is then applied to solve the flow of a horizontal jet penetrating a quiescent fluid from an entry port beneath the free surface.
Possible Magnetic Resonance Signal Due to the Movement of Counterions around a Polyelectrolyte with Rotational Symmetry  [PDF]
José A. Fornés
Advances in Nanoparticles (ANP) , 2015, DOI: 10.4236/anp.2015.41002
Abstract: Experimental, theoretical and computational studies revealed that the characteristic time scales involved in counterion dynamics in polyelectrolytes systems might span several orders of magnitude ranging from subnanosecond times to time scales corresponding to acoustic-like phonon mode frequencies, with an structural organization of counterions in charge density waves (CDWs). These facts raise the possibility of observing Magnetic Resonance (MR) signals due to the movement of counterions in polyelectrolytes. In case that this signal is detected in macroions or other biological systems, like micelles, vesicles, organeles, etc. with rotational symmetry, this method opens a new tool to measure with precission the counterions velocity.
Hydrodynamic Interactions Introduce Differences in the Behaviour of a Ratchet Dimer Brownian Motor  [PDF]
José A. Fornés
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2015, DOI: 10.4236/jbnb.2015.62008
Abstract: We use the Brownian dynamics with hydrodynamic interactions simulation in order to describe the movement of an elastically coupled dimer Brownian motor in a ratchet potential. The only external forces considered in our system were the load, the random thermal noise and an unbiased thermal fluctuation. We observe differences in the dynamic behaviour if hydrodynamic interactions are considered as compared with the case without them. In conclusion, hydrodynamic interactions influence substantially the dynamics of a ratchet dimer Brownian motor; consequently they have to be considered in any theory where the molecular motors are in a liquid medium.
Temperature Fluctuations in a Rectangular Nanochannel  [PDF]
José A. Fornés
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2015, DOI: 10.4236/jbnb.2015.63011
Abstract: We consider an incompressible fluid in a rectangular nanochannel. We solve numerically the three dimensional Fourier heat equation to get the steady solution for the temperature. Then we set and solve the Langevin equation for the temperature. We have developed equations in order to determine relaxation time of the temperature fluctuations, τT = 4.62 × 10-10s. We have performed a spectral analysis of the thermal fluctuations, with the result that temporal correlations are in the one-digit ps range, and the thermal noise excites the thermal modes in the two-digit GHz range. Also we observe long-range spatial correlation up to more than half the size of the cell, 600 nm; the wave number, q, is in the 106 m-1 range. We have also determined two thermal relaxation lengths in the z direction: l1 = 1.18 nm and l2 = 9.86 nm.
On the Asymptotics of Stochastic Restrictions  [PDF]
José A. Hernández
Theoretical Economics Letters (TEL) , 2016, DOI: 10.4236/tel.2016.64075
Abstract: This paper investigates inference methods to introduce prior information in econometric modelling through stochastic restrictions. The goal is to show that stochastic restrictions method estimator can be asymptotically more efficient than the estimator ignoring prior information and can achieve efficiency if prior information grows faster than the sample information in the asymptotics. The set up includes the nonlinear least squares and indirect inference estimators. The paper proposes a new indirect inference estimator that incorporates stochastic equality constraints on the parameters of interest. Finally, the proposed approach is applied to a macroeconomics model where high efficiency gains are shown.
Extreme Rainfall Indices in the Hydrographic Basins of Brazil  [PDF]
María C. Valverde, José A. Marengo
Open Journal of Modern Hydrology (OJMH) , 2014, DOI: 10.4236/ojmh.2014.41002
Abstract: The authors analyze climate extremes indices (CEI) of rainfall over the largest basins of the Brazilian territory: Amazon (AMA), S?o Francisco (SF), Tocantins (TO) and Paraná (PAR) rivers. The CEI represent the frequency of heavy precipitation events (R30mm and R95p) and short duration extreme rainfall (RX5day and RX1day). Droughts (CDDd) are identified based on two indicators: The longest dry period (CDD) and the annual cycle. The results demonstrate that CDDd, RX1day and RX5day occurred with more frequency and intensity in SF basin during El Ni?o events. CDDd was of greater magnitude in the TO basin during La Ni?a events, while an increase of RX1day occurred in El Ni?o. The strong El Ni?o events (1983 and 1997) caused more intense and frequent RX1day and R30mm over the PAR basin. Amazon droughts occurred in two out of the six El Ni?o events. Moreover, the relationship between the positive (negative) sea superficial temperatures anomalies in North (South) Tropical Atlantic and drought in AMA basin was corroborated. A gradual warming of SST was observed at the start of 2003 until it achieved a maximum in 2005 associated with the southwestern Amazon drought. The second highest anomaly of SST was in 2010 linked with drought that was more spatially extensive than the 2005 drought. The spatial distribution of annual trends showed a significant increase of CDD in south-eastern AMA, Upper SF, northern PAR and throughout the TO basins. R20mm, RX1day and RX5day tend to increase significantly in southwestern (northeast) PAR (AMA) and northwestern TO basins. Comparisons between CEI derived from daily precipitation data from Climate Prediction Center (CPCp) and of the ETA_HadCM3 model showed that the model overestimated RX1day, RX5day and CDD, in the four basins. Future scenarios show that dry periods will occur with greatest magnitude in all the basins until 2071-2099 time slice, while RX1day will be more intense in the TO and SF basins.
Electron Confinement Effect of Laser Dyes within Dendritic Structures  [PDF]
Francisco Márquez, María José Sabater
Journal of Encapsulation and Adsorption Sciences (JEAS) , 2011, DOI: 10.4236/jeas.2011.11001
Abstract: Dendrimers are a novel class of nanometric-size macromolecules with a regular tree-dimensional like array of branch units.1,2 Their synthetic availability in a wide range of sizes combined with their peculiar architecture makes them versatile building blocks for a wide range of potential applications.3 Some years ago, Meijer and co-workers reported that the modification of terminal amine functionalities of a fifth generation poly(propyleneimine) dendrimer (DAB-dendr-(NH2)64) with bulky substituents, (typically N-t-BOC protected phenylalanine), results in the formation of the so-called “dendritic box” (DAB-dendr-(NH-t-BOC-L-Phe)64).4 Within this macromolecular structure it is possible to encapsulate a variety of guest molecules due to the existence of internal cavities in the core. The photophysical properties of the guests can be modulated by the innovative electron confinement effect. In this respect, we wish to report that the emission frequency of organic dyes can be easily modulated by encapsulation in a dendritic box. The emission bands of dye molecules incorporated into a dendrimer can effectively be red shifted with respect to their emission in solution and contrary to other confined spaces of considerable hardness, the magnitude of this shifting can be regulated under appropriate experimental conditions. This peculiar effect could have unprecedented applications in the development of supramolecular devices relating to the frequency tuning of organic laser dyes.
Page 1 /513121
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.