731 research outputs found
Complementary use of transmission electron microscopy and atom probe tomography for the examination of plastic accommodation in nanocrystalline bainitic steels
No full textStochastic simulation of non-stationary continuous multifractal time series
No full textIntermittency is an ubiquitous property of fully developed turbulence, for Eulerian and Lagrangian fields, and for velocity, passive and active scalars. Intermittency corresponds to multi-scale high fluctuations, with some underlying long-range correlations. Such property is usually characterized using scaling approaches, verified using experimental or numerical data. However there are only few studies devoted to the generation of continuous stochastic processes having non-stationary multifractal properties, able to mimic Eulerian or Lagrangian velocity or passive scalar time series. Here we review recent works on this topic, and we provide stochastic simulations in order to verify the theoretical predictions. In the lognormal framework we provide a plane expressing the scale invariant properties of these simulations
Three-component velocity measurements in a momentum-conserving, axisymmetric, turbulent jet
No full textExperiments have been performed on a momentum conserving axisymmetric turbulent jet, the turbulence characteristics of which are well known [1]. Simultaneous three-component velocity measurements are acquired with high spatial and temporal resolution, using a new triple-sensor hotwire probe. Velocity and directional calibrations are performed using a dedicated automatic calibration system. Two experiments are performed; one for capturing the average velocity field in a 3D volume, and one for investigating the turbulence spectra in specific points in space. In the first experiment, measurements are performed in 9 equidistant cross-planes, from 10- to 50-diameters downstream of the nozzle using a computer-controlled traversing system. The spatial resolution is as low as 1 mm and the sampling rate was 10 kHz. In the second experiment, long velocity time histories are acquired with 50 kHz sampling rate to perform power spectral density computations for each velocity component. Preliminary results of velocity capture confirm the general characteristics of the turbulent jet. The power spectra at different positions indicate that the turbulent fluctuations are not isotropic at lower frequencies
Thermal etching method
No full textThe authors acknowledge financial support from
Ministerio de Ciencia y Tecnologı´a (MCYT) (Proyect
PETRI 95-0436-OP). F.G. Caballero thanks the
Direccio´n General de Investigacio´n de la Comunidad
Auto´noma de Madrid (CAM) for the financial
support in the form of a postdoctoral research grant.
C. Capdevila expresses his gratitude to the Consejo
Superior de Investigaciones Cientı´ficas for financial
support as a post-doctoral contract (I3P PC-2001-1).Peer reviewe
Joint scaling analysis of atmospheric velocity and wind power plant production
No full textIn a context of energy transition, wind energy is a source of clean energy with the potential of partially satisfying the growing demand. The main problem of this type of energy, and other types of renewable energy remains the discontinuity of the electric power produced in different scales, inducing large fluctuations also called intermittency. This intermittency of wind energy is inherent to the turbulent nature of wind. Here, we consider the relation between velocity and power output with two wind turbine databases. We focus on joint relations with Fourrier analysis, empirical mode decomposition (EMD), Time-dependent intrinsic correlation (TDIC). We also consider the causality using a new method of analysis of the causality between two time series
Reply to Comments on Comments on Kinetics Model of Isothermal Pearlite Formation in a 0.4C-1.6Mn Steel
No full textA theoretical model to calculate the evolution of austenite-to-pearlite transformation with time at a very wide temperature range
is presented. The model is based on thermodynamic calculations under partitioning local equilibrium (PLE) and no-partitioning
local equilibrium (NPLE) conditions.The authors acknowledge financial support from
Spanish Ministerio de Ciencia y Tecnolog ıa (MAT2001-
1617). F.G. Caballero would like to thank the Spanish
Ministerio de Ciencia y Tecnolog ıa and the Consejo
Superior de Investigaciones Cientif ıcas for the financial
support in the form of a Ramon y Cajal contract.Peer reviewe
Superbainita. Una nueva microestructura bainítica de alta resistencia
No full textEn este trabajo se muestran los resultados de investigaciones muy recientes que revelan la
posibilidad de obtener bainita por transformación isotérmica a temperaturas muy bajas, del
orden de 150 ºC, en aceros de alto carbono y silicio. La microestructura así obtenida no
tiene cementita y está formada por placas de ferrita bainítica extremadamente finas (20-40
nm de espesor) y láminas delgadas de austenita enriquecida en carbono. Estas
microestructuras son extraordinariamente duras (600 HV) y resistentes (2,5 GPa)Los autores agradecen el apoyo económico recibido.
F.G. Caballero y C. García-Mateo agradecen a
la Comisión Interministerial de Ciencia y Tecnología
(CICYT) (proyecto-MAT 2001-1617) y
H.K.D.H. Bhadeshia agradece a la EPSRC (Engineering
and Physical Science Research Council).
F. G. Caballero y C. Garcia-Mateo desean expresar
su agradecimiento al Ministerio de Educación y
Ciencia por el contrato Ramón y Cajal (Programa
RyC 2002/2004 respectivamente)Peer reviewe
Thermoelectric power studies on a martensitic stainless steel
No full textIn this work the different contributions to the thermoelectric power (TEP) measurement during the dissolution process of M23C6 carbides in an X45Cr13 stainless steel have been evaluated. Thus, the influences of carbon and chromium contents in solid solution in the austenite, the austenite grain boundaries and the microstructure on the TEP have been determinedThe authors acknowledge financial support from
Spanish Ministerio de Ciencia y Tecnolog ıa (MAT2000-
0412-P4-02). F.G. Caballero would like to thank
Spanish Ministerio de Ciencia y Tecnolog ıa for the
financial support in the form of a Ram on y Cajal contract
(Programa RyC 2002).Peer reviewe
'Prendet seyesçientos marcos': denaro vile e nobile nel Cantar de mio Cid
No full textAnálisis de las dinámicas monetarias en el Cantar de mio Ci
Precipitation of M23C6 carbides: thermoelectric power measurements
No full textThe volume fraction of M23C6 carbides precipitated during cooling in an X45Cr13 stainless steel has been estimated from the thermoelectric power (TEP) measurement. Likewise, the different contributions to the TEP measurement of samples cooled at different cooling rates have been determinedThe authors acknowledge financial support from
Spanish Ministerio de Ciencia y Tecnologı´a
(MAT2000-0412-P4-02). F.G. Caballero would like to
thank Spanish Ministerio de Ciencia y Tecnologı´a for
financial support in the form of a Ramo´n y Cajal contract
(Programa RyC 2002). A. Garcı´a-Junceda would
also like to express her gratitude to the Spanish Ministerio
de Educacio´ n, Cultura y Deporte for financial support
in the form of a PhD Research Grant (FPU Program).Peer reviewe
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