Academic literature on the topic 'Diffusing Diffusivity'

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Journal articles on the topic "Diffusing Diffusivity"

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Itto, Yuichi. "Entropy production rate of diffusivity fluctuations under diffusing diffusivity equation." Journal of Physics: Conference Series 1391 (November 2019): 012054. http://dx.doi.org/10.1088/1742-6596/1391/1/012054.

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Jain, Rohit, and K. L. Sebastian. "Diffusing diffusivity: Rotational diffusion in two and three dimensions." Journal of Chemical Physics 146, no. 21 (June 1, 2017): 214102. http://dx.doi.org/10.1063/1.4984085.

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Sposini, Vittoria, Aleksei Chechkin, and Ralf Metzler. "First passage statistics for diffusing diffusivity." Journal of Physics A: Mathematical and Theoretical 52, no. 4 (December 28, 2018): 04LT01. http://dx.doi.org/10.1088/1751-8121/aaf6ff.

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Cheung, S. C. H. "Methods to measure apparent diffusion coefficients in compacted bentonite clays and data interpretation." Canadian Journal of Civil Engineering 16, no. 4 (August 1, 1989): 434–43. http://dx.doi.org/10.1139/l89-073.

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The methods used to determine apparent diffusion coefficients and the appropriate parameters for modelling diffusion through compacted bentonite–water systems are assessed and discussed. The measured apparent diffusion coefficient can vary between methods. The discrepancies are shown to be due to heterogeneous diffusivities arising from the proximity of the surface of clay particles. Two different diffusivity pathways are identified and the diffusive flux is shown to be dictated by the charge of diffusing species, diffusion time, and soil fabric. Key words: apparent diffusion coefficient, methods, compacted bentonite, heterogeneous diffusion, parameters, pathways.
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Lawley, Sean D., and Christopher E. Miles. "Diffusive Search for Diffusing Targets with Fluctuating Diffusivity and Gating." Journal of Nonlinear Science 29, no. 6 (July 10, 2019): 2955–85. http://dx.doi.org/10.1007/s00332-019-09564-1.

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Singh, Rohit R., Ashok S. Sangani, Susan Daniel, and Donald L. Koch. "The combined hydrodynamic and thermodynamic effects of immobilized proteins on the diffusion of mobile transmembrane proteins." Journal of Fluid Mechanics 877 (August 27, 2019): 648–81. http://dx.doi.org/10.1017/jfm.2019.592.

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The plasma membranes of cells are thin viscous sheets in which some transmembrane proteins have two-dimensional mobility and some are immobilized. Previous studies have shown that immobile proteins retard the short-time diffusivity of mobile particles through hydrodynamic interactions and that steric effects of immobile proteins reduce the long-time diffusivity in a model that neglects hydrodynamic interactions. We present a rigorous derivation of the long-time diffusivity of a single mobile protein interacting hydrodynamically and thermodynamically with an array of immobile proteins subject to periodic boundary conditions. This method is based on a finite element method (FEM) solution of the probability density of the mobile protein diffusing with a position-dependent mobility determined through a multipole solution of Stokes equations. The simulated long-time diffusivity in square arrays decreases as the spacing in the array approaches the particle size in a manner consistent with a lubrication analysis. In random arrays, steric effects lead to a percolation threshold volume fraction above which long-time diffusion is arrested. The FEM/multipole approach is used to compute the long-time diffusivity far away from this threshold. An approximate analysis of mobile protein diffusion through a network of pores connected by bonds with resistances determined by the FEM/multipole calculations is then used to explore higher immobile area fractions and to evaluate the finite simulation cell size scaling behaviour of diffusion near the percolation threshold. Surprisingly, the ratio of the long-time diffusivity to the spatially averaged short-time diffusivity in these two-dimensional fixed arrays is higher in the presence of hydrodynamic interactions than in their absence. Finally, the implications of this work are discussed, including the possibility of using the methods developed here to investigate more complex diffusive phenomena observed in cell membranes.
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Kissinger, G., J. Dabrowski, Andreas Sattler, Timo Müller, and Wilfried von Ammon. "Two Paths of Oxide Precipitate Nucleation in Silicon." Solid State Phenomena 131-133 (October 2007): 293–302. http://dx.doi.org/10.4028/www.scientific.net/ssp.131-133.293.

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The coherent agglomeration of interstitial oxygen into single-plane and double-plane plates can explain the two peaks in the M-shaped nucleation curves in Czochralski silicon. The density of nucleation sites for the double-plane plates corresponds to the VO2 concentration. Ab initio calculations have shown that the agglomeration of oxygen atoms in single-plane and doubleplane plates is energetically favorable. These plates are under compressive strain. VO2 agglomeration plays only a minor role for modeling the M-shaped nucleation curves because of prior homogenization treatments. It is of much higher impact if as-grown wafers are subjected to nucleation anneals because of the higher vacancy concentration which was frozen in during crystal cooling. This results in higher nucleation rates at higher temperatures. Because the oxygen diffusivity below 700 °C is important for the nucleation rate and many controversial results about the diffusivity in this temperature range were published, we have analyzed the data from literature. We have demonstrated that the effective diffusivity of oxygen at temperatures below 700 °C which corresponds to the quasi equilibrium dimer concentration is very similar to the extrapolation from oxygen diffusivity at high temperature. The high effective diffusivities from out-diffusion and precipitation experiments, and the somewhat lower effective diffusivities from dislocation locking experiments are the result of an ongoing formation of fast diffusing dimers because the equilibrium is disturbed as the result of the strongly increasing difference in the diffusion length between interstitial oxygen and the fast diffusing dimer with decreasing temperature.
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Leaist, Derek G. "Coupled diffusion of butanol solubilized in aqueous sodium dodecylsulfate micelles." Canadian Journal of Chemistry 68, no. 1 (January 1, 1990): 33–35. http://dx.doi.org/10.1139/v90-008.

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Ternary interdiffusion coefficients have been measured for ten compositions of the system sodium dodecylsulfate (NaDS) + 1-butanol (BuOH) + water at 25 °C. The diffusivity of BuOH in this system is lower than in pure water because about one half of the alcohol is solubilized in the slowly-diffusing NaDS micelles. Yet, surprisingly, diffusion of the NaDS component transports only minor amounts of BuOH. Diffusion of the BuOH component, however, produces a substantial coupled flow of NaDS. Although added BuOH increases the solution viscosity and the size of the micelles, the diffusivity of the NaDS component does not change significantly. The Harned restricted diffusion method for the determination of electrolyte diffusivities is extended to electrolyte + nonelectrolyte solutes. Keywords: micelles, ionic; solubilization; diffusion, coupled.
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De Leo, Cinzia, Domenica Paoletti, and Dario Ambrosini. "Effect of noise on measurements of diffusivity in transparent liquid mixtures by digital speckle photography." European Physical Journal Applied Physics 82, no. 3 (June 2018): 30501. http://dx.doi.org/10.1051/epjap/2018180115.

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Interfacing two liquid mixtures in a diffusion cell induces noise in the initial state of the diffusing system, which produces a gap between the diffusion boundary and the ideally boundary assumed in the theory. Measured diffusivity values systematically drift with time and they are often corrected by using a linear shift of the zero-time of the process after sufficiently long time when the system reaches the free one-dimensional diffusion regime. In data analysis methods which involve optical correlation between pairs of successive digital images of the cell, it is not easy to establish how long the transient lasts. We show that when the initial perturbation between solution and solvent relaxes slowly toward the diffusive regime no simple zero-time correction can be applied.
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Nakashima, Y. "Self- diffusion of H2O in stevensite gel: effects of temperature and clay fraction." Clay Minerals 37, no. 1 (March 2002): 83–91. http://dx.doi.org/10.1180/0009855023710019.

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AbstractSelf-diffusion coefficients of water molecules (1H2O) in Na-stevensite gel were measured by pulsed-gradient spin-echo (PGSE) proton nuclear magnetic resonance (NMR). The effects of clay fraction (0.00 37.7 wt.%) and temperature (20.0 60.3°C) were studied. The results show: (1) phenomenologically, the H2O self-diffusivity in the clay gel, D, is expressed by D/D0 = exp( 0.0198w) where D0 is the H2O self-diffusivity in bulk water of the temperature and wis the clay weight fraction (wt.%). (2) The activation energy of the diffusivity in the stevensite gel is nearly equal to that in bulk water. Thus, the normalized diffusivity, D/D0, obeys a temperature-independent master curve. (3) The exponential dependence of D/D0 on wfor w <25 wt.% (≈ 12 vol.%) can be explained by a random walk model, in which unbound H2O molecules diffuse in the geometrically tortuous pore structure of randomly scattered clay mineral grains. (4) The measured diffusivity can also be explained by a model of unbound H2O diffusing in a polymer network with a specific meshsize or characteristic interval of the crosslinkage.
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Dissertations / Theses on the topic "Diffusing Diffusivity"

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Chmelik, Christian, Pavel Kortunov, Sergey Vasenkov, Taro Ito, Jörg Kärger, Jan Konatowski, Jens Weitkamp, and Douglas M. Ruthven. "Transport diffusivity in zeolites." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-196446.

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Larsen, Ryan J., and Charles F. Zukoski. "Self-diffusivity and free volume." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-188864.

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Heber, André, Markus Selmke, and Frank Cichos. "Thermal diffusivity measurements with a single nanoparticle." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-183781.

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Kremer, Heiko, Cristina Botero, Andreas P. Fröba, and Alfred Leipertz. "Thermal diffusivity of fluids by dynamic light scattering." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-196289.

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Rudakova, Maya, and Andrey Filippov. "Diffusivity of water in a biological model membrane." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-197030.

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Heber, André, Markus Selmke, and Frank Cichos. "Thermal diffusivity measurements with a single nanoparticle." Diffusion fundamentals 20 (2013) 89, S. 1, 2013. https://ul.qucosa.de/id/qucosa%3A13676.

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Kremer, Heiko, Cristina Botero, Andreas P. Fröba, and Alfred Leipertz. "Thermal diffusivity of fluids by dynamic light scattering." Diffusion fundamentals 2 (2005) 72, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A14405.

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Larsen, Ryan J., and Charles F. Zukoski. "Self-diffusivity and free volume: an ideal binary mixture." Diffusion fundamentals 11 (2009) 8, S. 1-2, 2009. https://ul.qucosa.de/id/qucosa%3A13928.

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Nechaev, Yury S. "Mechanisms of hydrogen sorption, solubility and diffusivity in carbon nanomaterials, relevance to the on-board storage problem: Mechanisms of hydrogen sorption, solubility and diffusivityin carbon nanomaterials, relevance to the on-board storage problem." Diffusion fundamentals 2 (2005) 100, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A14437.

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Rudakova, Maya, and Andrey Filippov. "Diffusivity of water in a biological model membrane: an NMR study." Diffusion fundamentals 2 (2005) 130, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A14472.

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Books on the topic "Diffusing Diffusivity"

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Fisher, D. J. Diffusivity in silicon, 1953 to 2009. Stafa-Zuerich, Switzerland: Trans Tech Publications Ltd, 2010.

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Center, NASA Glenn Research, ed. Novel diffusivity measurement technique. [Cleveland, Ohio]: National Aeronautics and Space Administration, Glenn Research Center, 2001.

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Kazuya, Idemitsu, and Dōryokuro Kakunenryō Kaihatsu Jigyōdan. Tōkai Jigyōsho., eds. Plutonium diffusivity in compacted bentonite. [Ibaraki-ken Naka-gun Tōkai-mura]: Tokai Works, Power Reactor and Nuclear Fuel Development Corporation, 1989.

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George C. Marshall Space Flight Center., ed. The Application of diffusion theory to the analysis of hydrogen desorption data at 25C̊. Marshall Space Flight Center, AL: National Aeronautics and Space Administration, George C. Marshall Space Flight Center, 1985.

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George C. Marshall Space Flight Center, ed. The Application of diffusion theory to the analysis of hydrogen desorption data at 25êC. Marshall Space Flight Center, AL: National Aeronautics and Space Administration, George C. Marshall Space Flight Center, 1985.

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Smith, Ralph C. Sinc-Galerkin estimation of diffusivity in parabolic problems. Hampton, Va: Institute for Computer Applications in Science and Engineering, 1991.

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L, Bowers Kenneth, and Langley Research Center, eds. Sinc-Galerkin estimation of diffusivity in parabolic problems. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1991.

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L, Bowers Kenneth, and Langley Research Center, eds. Sinc-Galerkin estimation of diffusivity in parabolic problems. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1991.

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Necati, Özışık M., ed. Unified analysis and solutions of heat and mass diffusion. New York: Dover, 1994.

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Gade, Herman G. Topographic influence on the determination of one-dimensional vertical diffusivity in sea basins. Bergen: Geophysical Institute, University of Bergen, 1995.

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Book chapters on the topic "Diffusing Diffusivity"

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Shewmon, Paul. "High Diffusivity Paths." In Diffusion in Solids, 189–222. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48206-4_6.

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Hensen, E. J. M., A. M. de Jong, and R. A. van Santen. "Positron Emission Profiling: a Study of Hydrocarbon Diffusivity in MFI Zeolites." In Adsorption and Diffusion, 277–328. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/3829_2007_014.

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Jumakulyyev, Ikram, and Thomas Schultz. "Fourth-Order Anisotropic Diffusion for Inpainting and Image Compression." In Mathematics and Visualization, 99–124. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-56215-1_5.

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AbstractEdge-enhancing diffusion (EED) can reconstruct a close approximation of an original image from a small subset of its pixels. This makes it an attractive foundation for PDE based image compression. In this work, we generalize second-order EED to a fourth-order counterpart. It involves a fourth-order diffusion tensor that is constructed from the regularized image gradient in a similar way as in traditional second-order EED, permitting diffusion along edges, while applying a non-linear diffusivity function across them. We show that our fourth-order diffusion tensor formalism provides a unifying framework for all previous anisotropic fourth-order diffusion based methods, and that it provides additional flexibility. We achieve an efficient implementation using a fast semi-iterative scheme. Experimental results on natural and medical images suggest that our novel fourth-order method produces more accurate reconstructions compared to the existing second-order EED.
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M.N.N., Miranda, and M. A. Silva. "Moisture Effective Diffusivity in Porous Media with Different Physical Properties." In Defect and Diffusion Forum, 207–12. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/3-908451-36-1.207.

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Belova, Irina V., and Graeme E. Murch. "Monte Carlo Modelling of the Effective Diffusivity in Composite Material." In Defect and Diffusion Forum, 103–8. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/3-908451-37-x.103.

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Drápala, Jaromir, P. Kubíček, J. Vřeštál, and M. Losertová. "Study of Reaction Diffusivity in the Copper–Indium–Tin Ternary System." In Defect and Diffusion Forum, 231–36. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/3-908451-35-3.231.

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Matsushita, Taishi, Lindsay Chapman, Rob Brooks, Ivan Egry, and Seshadri Seetharaman. "Thermal Diffusivity of TiAlNb and AlNi Alloys - The European IMPRESS Project." In Diffusion in Solids and Liquids III, 375–80. Stafa: Trans Tech Publications Ltd., 2008. http://dx.doi.org/10.4028/3-908451-51-5.375.

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Nechaev, Yury S., and G. A. Filippov. "Characteristics of Hydrogen Sorption, Solubility and Diffusivity in Graphites and Carbon Nanomaterials: Relevance to the On-Board Storage Problem." In Defect and Diffusion Forum, 143–46. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/3-908451-17-5.143.

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Lam, D. C. L., C. R. Murthy, and R. B. Simpson. "Marching Technique Solutions for Straight Plume Equations: Effects of Scale Dependent Diffusivity." In Effluent Transport and Diffusion Models for the Coastal Zone, 53–77. New York Inc.: Springer-Verlag, 2013. http://dx.doi.org/10.1002/9781118663561.ch4.

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Rothová, Vĕra, Jiří Buršík, Milan Svoboda, and Jiří Čermák. "Effect of Nickel Purity on Self-Diffusion along High-Diffusivity Paths." In Materials Science Forum, 245–48. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-469-3.245.

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Conference papers on the topic "Diffusing Diffusivity"

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Kulish, Vladimir V., José L. Lage, Connie C. W. Hsia, and Robert L. Johnson. "Red Blood Cell Distribution Effect on Lung Diffusing Capacity: A Macroscopic Analysis." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-2228.

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Abstract A novel mathematical model derived from fundamental engineering principles for simulating the spatial and temporal gas diffusion process within the alveolar region of the lung was presented recently by Koulich et al. [1]. The model depends on a physical property of the alveolar region termed effective diffusivity, function of the diffusivity, solubility, and interface geometry of each alveolar constituent. Unfortunately, the direct determination of the effective diffusivity of the alveolar region is impractical because of the difficulty in describing the internal geometry of each alveolar constituent. However, the transient solution of the macroscopic model can be used in conjunction with the lung diffusing capacity (measured in laboratory via the single-breath technique) to determine the effective diffusivity of the alveolar region. With the effective diffusivity known, the three-dimensional effects of red blood cell distribution on the lung diffusing capacity can be predicted via numerical simulations. The results, obtained for normal (random), uniform, center-cluster, corner-cluster, and several chain-like distributions, unveil a strong relationship between the type of cell distribution and the lung diffusing capacity.
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Nguyen, Trung, Kyung-Hee Park, Xin Wang, Jorge Olortegui-Yume, Tim Wong, David Schrock, Wonsik Kim, Patrick Kwon, and Bruce Kramer. "The Genesis of Tool Wear in Machining." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-52531.

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This paper presents a series of experimental and theoretical efforts that we have made in unraveling the tool wear mechanisms under steady state conditions in machining for the last few decades. Two primary modes of steady state tool wear considered in this paper are flank and crater wear. We preface this paper by stating that flank wear is explained as abrasive wear due to the hard phases in a work material while crater wear is a combination of abrasive wear and generalized dissolution wear which encompasses both dissolution wear as well as diffusion wear. However, the flank wear was not a function of the abrasive cementite content when turning low alloy steels with pearlitic microstructures. The machined surfaces of these alloys are examined to confirm the phase transformation (ferrite to austenite), which diminishes the effect of cementite content. In particular, the cementite phase present in low alloy steels dissociates and diffuses into the transformed austenitic phase during machining. Dissolution wear is claimed to describe the behavior of crater wear at high cutting speeds. The original dissolution mechanism explains the crater wear in the machining of ferrous materials and nickel alloys at high cutting speeds, but the generalization of the dissolution wear is necessary for titanium alloys. In machining titanium alloys, the original dissolution mechanism did not show a good correlation with experimental results; generally the diffusivity of the slowest diffusing tool constituent in titanium limits the wear rate. The phase transformation from alpha (HCP) to beta (BCC) phases can also take place in machining titanium alloys, which drastically increases the crater wear due to the few orders of magnitude increase in diffusivity. The most puzzling issue is however the presence of the scoring marks even though no hard inclusion is typically present in titanium alloys. This is finally explained by the heterogeneity in the microstructure due to the anisotropic hardness of alpha (HCP) phase (the hardness in c-direction is 50% higher than the hardness in other directions) and the presence of lamellar microstructure (alternating layers of alpha and beta). The lamellar microstructure has not only the in-plane anisotropic hardness but also a greater hardness than other phases. Even though we cannot claim to fully understand the physics behind tool wear, our combined approaches have unveiled some elementary wear mechanisms.
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Chao, Gabriel, Cees Oomens, Rene van Donkelaar, and Frank Baaijens. "Effects of Anomalous Diffusion Mechanisms in Developing Tissue Engineered Constructs." In ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-176507.

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Many diffusive processes in biological systems refuse to obey the standard laws of diffusion. In normal diffusion, the diffusivity can be considered constant and the concentration of the diffusive particles follows Fick’s law. However, in highly heterogeneous materials such as tissues, the complex microgeometry of the medium imposes serious restrictions to the mobility of the particles. This scenario is known as anomalous diffusion. Experiments in diverse biological systems including diffusion in the extracellular space of the brain [1], morphogen movement in the extracellular environment [2], protein movement inside cells [3], identified anomalous, rather than Fickian, transport.
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Pascucci, Andrea. "On a convection-diffusion equation with partial diffusivity." In Proceedings of the 4th European Conference. WORLD SCIENTIFIC, 2002. http://dx.doi.org/10.1142/9789812777201_0020.

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Montoya Arroyave, Isabel. "Drug diffusion across skin with diffusivity spatially modulated." In SPIE Sensing Technology + Applications, edited by Brian M. Cullum and Eric S. McLamore. SPIE, 2014. http://dx.doi.org/10.1117/12.2049766.

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Iwasaki, Daigo, Yoshio Utaka, Yutaka Tasaki, and Shixue Wang. "Oxygen Diffusion Characteristics of Gas Diffusion Layers With Moisture." In ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2008. http://dx.doi.org/10.1115/icnmm2008-62106.

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The mass transfer characteristics of the gas diffusion layer (GDL) in a polymer electrolyte fuel cell (PEFC) are closely related to the performance. In this study, the oxygen diffusivity of paper and cloth type porous media, which are generally used as GDLs, were measured with respect to liquid water content, using experimental apparatus consisting of an oxygen sensor based on a galvanic battery. Paper type porous media, both non treated and hydrophilic treated, and the cloth type porous media with non treated surface were used as GDL specimens. The porosity of both specimens was almost the same, but the representative pore diameter of the cloth type GDL was approximately three times larger than that of paper type GDL. Two methods were utilized to impregnate liquid water into the porous GDL media to realize different water distributions in the specimens at the initial state; vacuum impregnation and moist air condensation impregnation. The oxygen diffusivities of the specimens were measured to clarify the influence of the two impregnation methods on the oxygen diffusion characteristics. Moreover, the relation between the measurement of oxygen diffusivity and the visualization of the liquid water distribution by using Neutron Radiography [Tasaki et al. (2007)] was investigated for the paper and cloth type GDLs. The oxygen diffusivity in the paper type porous media decreased precipitously with increasing water saturation by the vacuum impregnation method, whereas the diffusivity decrease was relatively small when impregnated by the moist air condensation method. For the cloth type porous media with weaving threads, oxygen diffusion characteristics were independent of the water impregnation method. Thus, the porous medium’s microstructure plays an important role in determining diffusion characteristics, especially in the presence of liquid water.
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Paoletti, Domenica, Dario Ambrosini, Nasser Rashidnia, and Ramaswamy Balasubramaniam. "Unusual Optical Techniques in Diffusivity Measurements." In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95678.

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In studying hydrodynamic instabilities between two miscible fluid mixtures one often faces the problem of assigning a reliable value to diffusion coefficients. As for diffusion between two binary mixtures such as water and glycerin, water and salt, etc., no complete data are available in the literature. This shortage of data justifies the search for simple and accurate experimental techniques. Optical techniques are now recognized as powerful tools to investigate fluid flow phenomena in transparent media. In particular, in this paper we discuss three different, recently proposed, optical techniques for diffusivity measurements, namely speckle decorrelation, common path shearing interferometry and digital moire´. Although all these techniques depend on variation of the index of refraction in a transparent fluid, each method involves the use of specific instrumentation, with experimental uncertainties and ranges of applicability which differ from case to case. A comparison of the techniques is presented as well as a discussion of their possible integration.
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Wu, R., X. Zhu, Q. Liao, H. Wang, and Y. D. Ding. "Pore Network Modeling of Oxygen Diffusion in Gas Diffusion Layer of Proton Exchange Membrane Fuel Cells." In ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer. ASMEDC, 2009. http://dx.doi.org/10.1115/mnhmt2009-18433.

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In the present study, a three dimensional pore network, consisting of spherical pores and cylindrical throats, is developed to simulate the oxygen diffusion and liquid water permeation in gas diffusion layer (GDL) in low-temperature fuel cell. Oxygen transport in the throats is described by Fick’s law and liquid water permeation in the network is simulated using percolation invasion algorithm. The effects of heterogeneity of GDL, connectivity of pores, and liquid water saturation on oxygen effective diffusivity are investigated respectively. The simulation results show that the GDL structure has a significant influence on the oxygen and water transport in the GDL. The oxygen effective diffusivity increases with increasing pore connectivity and decreasing heterogeneity. The shielding effect of large throats by smaller ones enhances with increasing heterogeneity of the network. Furthermore, the oxygen transportation is blocked in the presence of liquid water permeation. Thus the oxygen effective diffusivity drops significantly with increasing water saturation.
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Yuan, Tai-Yi, Alicia R. Jackson, Chun-Yuh Huang, and Weiyong Gu. "Strain Dependent Oxygen Diffusivity in Bovine Annulus Fibrosus." In ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-192842.

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Abstract:
Intervertebral disc (IVD) is the largest avascular structure in the human body and nutrition supply into IVD is mainly through diffusion from the peripheral blood vessels. Poor nutrition supply to the disc is believed to be one of the causes for disc degeneration. While many studies have aimed at studying and analyzing the effect of mechanical loading on water content, chemical composition, and nutritional levels in IVD [1–3], no study has been reported to investigate the effect of mechanical compression on oxygen diffusion in the IVD tissue. The objective of this study was to determine oxygen diffusivity in annulus fibrosus (AF) samples under different levels of compression.
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10

Sahli, A., S. Bellagha, and S. Bornaz. "Salt Diffusion and Salt Diffusivity in Sardine Muscle (Sardinella aurita)." In 13th World Congress of Food Science & Technology. Les Ulis, France: EDP Sciences, 2006. http://dx.doi.org/10.1051/iufost:20060347.

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Reports on the topic "Diffusing Diffusivity"

1

Marinak, M. An extended diffusive model for calculating thermal diffusivity from single monopole tokamak heat pulse propagation. Office of Scientific and Technical Information (OSTI), February 1990. http://dx.doi.org/10.2172/7231039.

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