Persistent slip bands

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Prediction of grain boundary stress fields induced by the impingement of persistent slip bands

Prediction of grain boundary stress fields induced by the impingement of persistent slip bands

Introduction Cyclic deformation of fcc metals often leads to the creation of slip bands within slabs of grains which remain. These slip bands are called persistent slip bands (PSBs) since they reappear at the same positions after polishing the samples and recycling. PSBs cross the grains and are characterized by their specific extrusion shape through GBs (as shown in Figure 1 below) and free surfaces. The shapes and characteristic lengths of PSBs depend mostly of the considered material, grain size, and orientation of PSBs Burgers vectors [1], [2].
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Prediction of intergranular micro-cracks initiation induced by the impingement of persistent slip bands on grain boundaries

Prediction of intergranular micro-cracks initiation induced by the impingement of persistent slip bands on grain boundaries

Prediction of intergranular micro-cracks initiation induced by the impingement of persistent slip bands on grain boundaries... PREDICTION OF INTERGRANULAR MICRO-CRACK INITIATION INDUCED[r]

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Prediction of intergranular micro-crack initiation induced by the impingement of persistent slip bands on grain boundaries

Prediction of intergranular micro-crack initiation induced by the impingement of persistent slip bands on grain boundaries

• Analytical model for the prediction of intergranular, transgranular and twin boundaries microcrack initiation TMS 2018 | MARS 12th 2018 | 23.. Nuclear Energy Division Nuclear Mat[r]

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Beyond the no-slip boundary condition

Beyond the no-slip boundary condition

The viability of the volume-velocity boundary condition ( 13 ) can only be ascertained by examining pertinent experi- mental evidence bearing thereon, with the outcome reflecting on the correctness or lack thereof of this hypothesized boundary condition. This empirical attitude is analogous to that originally adopted by Stokes [ 3 ] and followed ever since with respect to the conventional no-slip fluid-mechanical mass- velocity boundary condition v m = 0 [ 1 , 2 ] at solid surfaces. There, the credibility of Stokes’ hypothesis has been tested in the context of elementary, well-defined situations. The latter were sufficient in number, variety, and simplicity of interpretation, such as to render Stokes’ no-slip hypothesis credible as a general rule without, however, necessarily supposing it to be inviolable. In what follows we adapt the same empirical verification scheme to the present volume velocity case, arguing that Eq. ( 13 ) overrides Stokes’ no-slip condition in situations where fluid compressibility is sensible.
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Stick-slip instabilites in magnetorheological fluids

Stick-slip instabilites in magnetorheological fluids

N.2.3.1. Shear flow between parallel plates Experiments of shear flow between parallel plates were carried out at 25 ºC using a controlled-stress magnetorheometer (MCR300, Physica-Anton Paar, Austria). The measuring system geometry was a 20 mm diameter parallel-plate set for a gap width of 0.35 mm. In order to prevent wall slip, it can be enough to use surfaces with roughness of a size higher than particle size [BAR 95]. Accordingly, in the case of MR fluid 3, the commercial parallel plates supplied with the magnetorheometer MCR300 were used, since particle size was of the order of the tens of nanometers in this case, which was smaller than the roughness of smooth surfaces. On the other hand, in the case of MR fluid 1, particle size was of the order of microns and, consequently, we used a pair of homemade parallel disks with roughened surfaces [LOP 12a]. Measurements were performed upon application of a magnetic field, which was applied by means of the commercial solenoid of the magnetorheometer MCR300 in the case of MR fluid 3, and by means of a homemade solenoid placed coaxially with the axis of the parallel disks in the case of MR fluid 1. The fields generated by these solenoids were reasonably homogeneous, especially in the case of the homemade one. Precise details about the distribution of field within the measuring system in the case of the commercial solenoid supplied with the magnetorheometer MCR300 can be found in [LOP 10].
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Generalized slip condition over rough surfaces

Generalized slip condition over rough surfaces

of the turbulent energy found with the RSP is no surprise, since small-size protrusions are known to act as turbulence promoters. In contrast, the fact that condition ( 2.28 ) results in a decrease of the turbulent energy, even with respect to the SSP case, reveals a clear limitation of the present ‘equivalent’ boundary condition. To understand this behaviour, it must be kept in mind that if a pure shear-free condition is applied at the surface of a sphere (which in this limit is equivalent to a spherical gas bubble), no instability of the wake (hence no transition to turbulence) takes place, however large the Reynolds number might be (Magnaudet & Mougin 2007 ). Increasing the slip length from zero to infinity is equivalent to gradually changing the boundary condition from no slip to shear free. If one does so while maintaining the Reynolds number fixed, the fluctuating energy is decreased until it is totally suppressed (see e.g. Legendre, Lauga & Magnaudet ( 2009 ) in the case of the flow past a circular cylinder). Here, ( 2.28 ) results in a boundary condition which is intermediate between the no-slip and free-shear ones. Hence, it is no surprise that the spectra displayed in figure 13 indicate that there is less turbulence in the flow past the ESP than in those past the other two types of sphere.
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Slip length measurement of gas flow

Slip length measurement of gas flow

thermal non-equilibrium state, where the usual Navier Stokes equations are not valid. The thickness of this layer is of the same order of magnitude as the mean free path λ. The initial expression (1) of the velocity slip provided by Maxwell, which is in a dimensionless form of the first order in Kn, has further been discussed by numerous researchers, and various improved slip boundary conditions, including corrective coef ficients and higher orders, have been proposed tentatively in the literature [ 17 ]. Unfortunately, there is currently no clear

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Fiche technique - 541 Eurofix Anti Slip

Fiche technique - 541 Eurofix Anti Slip

• Protection du revêtement : Si les conditions d'achèvement du chantier nécessitent la pose d'une protection sur le revêtement, celle-ci ne doit être disposée qu'après 72 heures, délai [r]

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Generalized slip condition over rough surfaces

Generalized slip condition over rough surfaces

6. Concluding remarks The main result of the present paper consists in the macroscopic boundary condition ( 2.28 ) which is applicable to general incompressible flows over microscopically rough surfaces. This condition states that the velocity components tangent to the equivalent smooth wall depend on the strain-rate tensor characterizing the outer flow at the upper limit of the rough layer. A third-order slip tensor that depends directly on the local geometry of the rough layer is associated with the strain rate of the outer flow. Within the homogenization-based framework used here, this generalized slip condition appears as the first-order correction to the usual no-slip condition. We assessed its validity via the use of DNS in a non-trivial, fully three-dimensional configuration in the presence of strong inertia effects. Macroscopic simulations based on this new boundary condition, in which the volume-averaged slip tensor is computed by solving the microscopic problem ( 2.21 ), show good agreement with the DNS results in the laminar regime. The set of equations governing this problem arise from the development of the boundary condition without further assumptions, thanks to the rational framework provided by the homogenization approach.
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Direct numerical simulation of unsheared turbulence diffusing toward a free-slip or no-slip surface

Direct numerical simulation of unsheared turbulence diffusing toward a free-slip or no-slip surface

x ) and vertical (ω z 2 ) vorticity components have been plotted across the flow. A vorticity isotropy factor I ω can then be defined as the square root of the ratio ω x 2 /ω 2 z . Its evolution is plot- ted in figure 4(b) for the two cases and stresses the differences in the inner-layer behaviours. Across the pure-diffusion region, the value I ω remains fairly constant, slightly above unity. Then, proceeding toward the surface, the value of I ω rises significantly while getting close to the surface in the upper part of the outer layer. Vorticity profiles obtained by Leighton et al. [15] for the free surface of an open- channel flow or Shen et al. [16] for the interaction between a time-evolving wake and a free-surface indicate a similar behaviour for I ω . The enstrophy budgets pre- sented in the same references show that the rise of the isotropy factor toward the surface is a blockage-layer effect due to the prevalence of vortex stretching along the tangential direction in this region. Entering the inner layers, the evolutions of I ω finally diverge: they exhibit a steep return to zero in the FS case and keep in- creasing up to infinity in the SW case, consistently with each boundary condition. Following Campagne et al. [14], the thickness δ s of the slip layer in the FS case will be defined as the distance to the surface at which I ω reaches its maximum, here we find δ s = 0.035 l f . In the SW case, a consistent definition of the thickness of the viscous layer (δ v ) will need an examination of the kinetic-energy budget, and cannot be given at this stage.
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3D Wavelet Sub-Bands Mixing for Image Denoising

3D Wavelet Sub-Bands Mixing for Image Denoising

All these methods aim at removing noise while preserving relevant image information. The trade-off between noise removal and image preservation is performed by tuning the filter parameters, which is not an easy task in practice. In this paper we propose to overcome this problem with a 3D sub-bands wavelet mixing. As in [17], we have chosen to combine a multiresolution approach with the NL-means filter [4] which has recently shown very promising results.

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Persistent currents in Dirac fermion rings

Persistent currents in Dirac fermion rings

Section IV treats the case of a single impurity in the ring. In the continuum model, a nonmagnetic impurity has no effect on the persistent current, because it does not couple the left- and right-movers. Nevertheless, the lattice model lacks time-reversal symmetry (TRS). Hence there is no Kramers degeneracy to protect the crossing in the energy-flux spectrum. Consequently, even nonmagnetic impurities can open up gaps and lead to a suppression of the PC. In contrast, the case of a magnetic impurity allows a direct comparison between the lattice and continuum model. Because TRS is broken in both models, the same mechanism induces backscattering, thereby producing a decrease of the PC. The analytical expression obtained in the case of a delta-like impurity is cross-checked with the numerical results revealing a good agreement for any impurity strength, after a renormalization of impurity potential in the continuum model.
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Field, Experimental, and Numerical Studies of Deformation Localization Bands

Field, Experimental, and Numerical Studies of Deformation Localization Bands

Presentations were oriented toward detailed field analysis of deformation bands from the United States and France, with emphasis on grain-scale structure (R. Schultz, University of Nevada; R. Soliva, Geosciences Montpellier (GM)) and impact on permeabil- ity (C. Wibberley, Total). Polyaxial as well

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Mid-Miocene strike-slip in continental Greece

Mid-Miocene strike-slip in continental Greece

Classical view of the geodynamic evolution of Greece:1/ Classical back-arc extension with N150 normal faults 2/ followed by mainly N50 dextral strike-slip faults (Gulf of Evvia and Corinth) since 5 Ma marking the impact of the NAF in the tectonic system

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Spatial and temporal evolution of a long term slow slip event: the 2006 Guerrero Slow Slip Event

Spatial and temporal evolution of a long term slow slip event: the 2006 Guerrero Slow Slip Event

Our results show that the 2006 SSE recorded data can be de- scribed by a slip dislocation model characterized by a simple smooth ramp function. Such a functional form has been widely used to anal- yse regular earthquakes (e.g. Hernandez et al. 1999; Liu et al. 2006). The time duration of slip at a given point (rise time) is a key piece of information that helps to understand the rupture process. The rise time found for the Guerrero SSE is about half of the total duration. The duration of slip is then large with respect to the total duration of the rupture process, which means that there is a long distance interaction between points of the fault during the dynamic process (Fig. 9). This point differs from regular earthquakes: the rise time associated to a magnitude 7.0–7.5 regular earthquake (e.g. Landers 1992) being only 10–15 per cent of the total duration (Wald & Heaton 1994; Cotton & Campillo 1995).
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Credit market imperfections and persistent unemployment

Credit market imperfections and persistent unemployment

with no credit market frictions, a worker with skill level a* can accumulate enough wealth to. eventually become an entrepreneur[r]

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Asymmetric Cell Division: A Persistent Issue?

Asymmetric Cell Division: A Persistent Issue?

(2012) demonstrate that cell division in mycobacteria is asymmetric, producing daughter cells that differ in size, growth rate, and susceptibility to antibiotics.. More than two billion [r]

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Algorithms for persistent autonomy and surveillance

Algorithms for persistent autonomy and surveillance

2.1 Persistent Surveillance The problem of persistent surveillance has been studied in a variety of real-world in- spired monitoring applications such as underwater marine monitoring and detection of natural phenomena [6,11,21,22,25,26,30,32–34,36]. These approaches generally as- sume that the robot can obtain measurements while moving and generate paths that optimize an application-specific monitoring objective, such as mutual information. Further examples of monitoring objectives include facilitating high-value data collec- tion for autonomous underwater vehicles [32], keeping a growing spatio-temporal field bounded using speed controllers [34], and generating the shortest watchman routes along which every point in a given space is visible [12].
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Economic Development: Is Social Capital Persistent?

Economic Development: Is Social Capital Persistent?

• We also believe to come closer to the causal relationship of trust and economic performance. This is executed, not in the sense of repeated cross-section regressions (cross-country study), but, in the sense of taking all the available data together - in other words, pooled unbalanced multiple cross-section datasets. And our hypothesis being is the generalized trust persistent? A longitudinal analysis is not possible, since we do not observe same countries included in the values surveys over different survey waves. 31 A repeated cross- section is helpful, but not sufficient - it loses its utility since some of the variables’ significance changes drastically over survey waves and sources (WVS, EVS, European Social Survey, Global Barometer Surveys etc.). 32 Hence, the most appropriate approach is to pool all these seemingly similar databases together; and to have wave fixed effects to control for the aforementioned problems. 33
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Inherited state of stress as a key factor controlling slip and slip mode: inference from the study of a slow slip event in the Longitudinal Valley, Taiwan

Inherited state of stress as a key factor controlling slip and slip mode: inference from the study of a slow slip event in the Longitudinal Valley, Taiwan

rectangle outlines the SSE rupture area and black star denotes the Chengkung earthquake epicenter. Black curves give the contour lines of the coseismic (b,c) and postseismic (d) slip distribution models (in meter). Cumulative slip along the long-term rake for the A4 area and for the column c12 (see (a)) are given respectively in (e) and (f). For area A4,

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