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Bengterik Mellander - One of the best experts on this subject based on the ideXlab platform.
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resolving distribution of Relaxation Times in poly propylene glycol on the crossover region
arXiv: Soft Condensed Matter, 2004Co-Authors: Enis Tuncer, Maurizio Furlani, Bengterik MellanderAbstract:In this paper, a recently developed numerical technique [{\em Tuncer E and Guba{\'n}ski S M, IEEE Trans Diel El Insul {\bf 8}(3)(2001) 310-320}] is applied to poly(propylene glycol) complex dielectric data to extract more information about the molecular Relaxation processes. The method is based on a constrained-least-squares (\clsq) data fitting procedure together with the Monte Carlo (\mc) method. We preselect the number of Relaxation Times with no {\em a-priori} physical assumption, and use the Debye single Relaxation as ``kernel'', then the obtained weighting factors at each \mc step from the \clsq method builds up a Relaxation Time Spectrum. When the analysis is repeated for data at different temperatures a {\em Relaxation-image} is created. The obtained Relaxation are analyzed using the Lorentz (Cauchy) distribution, which is a special form of the L{\'e}vy statistics. In the present report the $\beta$ and $\alpha$ Relaxations are resolved for the \ppg. A comparison of the Relaxations to those earlier reported in the literature indicate that the presented method provides additional information compared to methods based on empirical formulas. The distribution of Relaxation Times analysis is especially useful to probe the crossover region where the $\alpha$- and $\beta$- Relaxations merge and the results show that the Relaxation after the crossover region at higher temperatures is Arrhenius-type as the $\beta$-Relaxation. Moreover, this Relaxation is more likely to be the continuation of the $\beta$-Relaxation, but with a different activation energy.
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resolving distribution of Relaxation Times in poly propylene glycol on the crossover region
Journal of Applied Physics, 2004Co-Authors: Enis Tuncer, Maurizio Furlani, Bengterik MellanderAbstract:In this article, a recently developed numerical technique [E. Tuncer and S. M. Gubanski, IEEE Trans. Dielectr. Electr. Insul. 8, 310 (2001)] is applied to poly(propylene glycol) (PPG) complex dielectric data to extract more information about the molecular Relaxation processes. The method is based on a constrained-least-squares (C–LSQ) data fitting procedure together with the Monte Carlo method. We preselect the number of Relaxation Times with no a priori physical assumption, and use the Debye single Relaxation as “kernel,” then the obtained weighting factors at each MC step from the C–LSQ method builds up a Relaxation Time Spectrum. When the analysis is repeated for data at different temperatures a Relaxation image is created. The obtained Relaxation are analyzed using the Lorentz (Cauchy) distribution, which is a special form of the Levy statistics. In the present report the β and α Relaxations are resolved for the PPG. A comparison of the Relaxations to those earlier reported in the literature indicate ...
Yogesh M Joshi - One of the best experts on this subject based on the ideXlab platform.
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signatures of physical aging and thixotropy in aqueous dispersion of carbopol
Physics of Fluids, 2019Co-Authors: Mayank Agarwal, Yogesh M JoshiAbstract:In this work, we investigate signatures of physical aging in an aqueous dispersion of Carbopol that shows yield stress and weak enhancement in elastic modulus as a function of Time. We observe that the creep curves, as well as strain recovery, show a significant dependence on waiting Time elapsed since shear melting. The corrected strain, which is the strain in excess of the recovered strain, has been observed to show Time–waiting Time superposition in the effective Time domain, wherein Time is normalized by Time dependent Relaxation Time that shows a power-law dependence. The corresponding power law exponent, which is close to unity in a limit of small stresses, decreases with stress and tends to zero as stress approaches the yield stress. For a range of stresses, the material shows Time–stress superposition suggesting the shape of the evolving Relaxation Time Spectrum to be independent of the Time as well as the stress. This work, therefore, suggests the presence of physical aging in an aqueous dispersion of Carbopol even though the elastic modulus shows only a weak enhancement. We also discuss the Andrade type of creep behavior in aqueous Carbopol dispersion.In this work, we investigate signatures of physical aging in an aqueous dispersion of Carbopol that shows yield stress and weak enhancement in elastic modulus as a function of Time. We observe that the creep curves, as well as strain recovery, show a significant dependence on waiting Time elapsed since shear melting. The corrected strain, which is the strain in excess of the recovered strain, has been observed to show Time–waiting Time superposition in the effective Time domain, wherein Time is normalized by Time dependent Relaxation Time that shows a power-law dependence. The corresponding power law exponent, which is close to unity in a limit of small stresses, decreases with stress and tends to zero as stress approaches the yield stress. For a range of stresses, the material shows Time–stress superposition suggesting the shape of the evolving Relaxation Time Spectrum to be independent of the Time as well as the stress. This work, therefore, suggests the presence of physical aging in an aqueous dispersi...
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signatures of physical aging and thixotropy in aqueous dispersion of carbopol
arXiv: Soft Condensed Matter, 2019Co-Authors: Mayank Agarwal, Yogesh M JoshiAbstract:In this work, we investigate signatures of physical aging in an aqueous dispersion of Carbopol that shows yield stress and weak enhancement in elastic modulus as a function of Time. We observe that the creep curves, as well as strain recovery, show a significant dependence on waiting Time elapsed since shear melting. The corrected strain, which is the strain in excess of the recovered strain, has been observed to show Time waiting Time superposition in the effective Time domain, wherein Time is normalized by Time-dependent Relaxation Time that shows a power-law dependence. The corresponding power law exponent, which is close to unity in a limit of small stresses, decreases with stress and tends to zero as stress approaches the yield stress. For a range of stresses, the material shows Time stress superposition suggesting the shape of the evolving Relaxation Time Spectrum to be independent of the Time as well as the stress. This work, therefore, suggests the presence of physical aging in an aqueous dispersion of Carbopol even though the elastic modulus shows only a weak enhancement. We also discuss Andrade type of creep behavior in aqueous Carbopol dispersion.
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tailoring Relaxation Time Spectrum in soft glassy materials
arXiv: Soft Condensed Matter, 2013Co-Authors: Manish Kaushal, Yogesh M JoshiAbstract:Physical properties of out of equilibrium soft materials depend on Time as well as deformation history. In this work we propose to transform this major shortcoming into gain by applying controlled deformation field to tailor the rheological properties. We take advantage of the fact that deformation field of a certain magnitude can prevent particles in an aging soft glassy material from occupying energy wells up to a certain depth, thereby populating only the deeper wells. We employ two soft glassy materials with dissimilar microstructures and demonstrate that increase in strength of deformation field while aging leads to narrowing of Spectrum of Relaxation Times. We believe that, in principle, this philosophy can be universally applied to different kinds of glassy materials by changing nature and strength of impetus.
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delayed yielding in creep Time stress superposition and effective Time theory for a soft glass
Soft Matter, 2012Co-Authors: Bharat Baldewa, Yogesh M JoshiAbstract:In this work we investigate creep flow of aqueous suspension of Laponite, a model soft glassy material, at different aging Times and stresses. We observe that this system shows Time—aging Time—stress superposition over a range of aging Times and stresses when a real Time scale is transformed into an effective Time scale. Existence of superposition in an effective Time domain facilitates prediction of long and very short Time rheological behavior. Analysis of the observed behavior from an effective Time approach suggests that superposition is possible only when the shape of a Relaxation Time Spectrum is preserved at various aging Times and stresses. We also observe that creep curves at low aging Times and greater stresses demonstrate delayed but sudden yielding. The critical Time, at which material yields, increases with increase in aging Time and decrease in stress. We argue that local rejuvenation of part of the glassy material causes variation in the rate of evolution of Relaxation modes. The resulting interplay between aging and rejuvenating modes leads to delayed yielding as observed experimentally.
Enis Tuncer - One of the best experts on this subject based on the ideXlab platform.
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resolving distribution of Relaxation Times in poly propylene glycol on the crossover region
arXiv: Soft Condensed Matter, 2004Co-Authors: Enis Tuncer, Maurizio Furlani, Bengterik MellanderAbstract:In this paper, a recently developed numerical technique [{\em Tuncer E and Guba{\'n}ski S M, IEEE Trans Diel El Insul {\bf 8}(3)(2001) 310-320}] is applied to poly(propylene glycol) complex dielectric data to extract more information about the molecular Relaxation processes. The method is based on a constrained-least-squares (\clsq) data fitting procedure together with the Monte Carlo (\mc) method. We preselect the number of Relaxation Times with no {\em a-priori} physical assumption, and use the Debye single Relaxation as ``kernel'', then the obtained weighting factors at each \mc step from the \clsq method builds up a Relaxation Time Spectrum. When the analysis is repeated for data at different temperatures a {\em Relaxation-image} is created. The obtained Relaxation are analyzed using the Lorentz (Cauchy) distribution, which is a special form of the L{\'e}vy statistics. In the present report the $\beta$ and $\alpha$ Relaxations are resolved for the \ppg. A comparison of the Relaxations to those earlier reported in the literature indicate that the presented method provides additional information compared to methods based on empirical formulas. The distribution of Relaxation Times analysis is especially useful to probe the crossover region where the $\alpha$- and $\beta$- Relaxations merge and the results show that the Relaxation after the crossover region at higher temperatures is Arrhenius-type as the $\beta$-Relaxation. Moreover, this Relaxation is more likely to be the continuation of the $\beta$-Relaxation, but with a different activation energy.
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resolving distribution of Relaxation Times in poly propylene glycol on the crossover region
Journal of Applied Physics, 2004Co-Authors: Enis Tuncer, Maurizio Furlani, Bengterik MellanderAbstract:In this article, a recently developed numerical technique [E. Tuncer and S. M. Gubanski, IEEE Trans. Dielectr. Electr. Insul. 8, 310 (2001)] is applied to poly(propylene glycol) (PPG) complex dielectric data to extract more information about the molecular Relaxation processes. The method is based on a constrained-least-squares (C–LSQ) data fitting procedure together with the Monte Carlo method. We preselect the number of Relaxation Times with no a priori physical assumption, and use the Debye single Relaxation as “kernel,” then the obtained weighting factors at each MC step from the C–LSQ method builds up a Relaxation Time Spectrum. When the analysis is repeated for data at different temperatures a Relaxation image is created. The obtained Relaxation are analyzed using the Lorentz (Cauchy) distribution, which is a special form of the Levy statistics. In the present report the β and α Relaxations are resolved for the PPG. A comparison of the Relaxations to those earlier reported in the literature indicate ...
Yizhong Jiang - One of the best experts on this subject based on the ideXlab platform.
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a Time domain induced polarization method for estimating permeability in a shaly sand reservoir
Geophysical Prospecting, 2006Co-Authors: Maosong Tong, Weinan Wang, Yizhong JiangAbstract:It is known that the Time-domain induced-polarization decay curve for a shaly sand reservoir depends on the pore structure of the reservoir, and this curve can be used to estimate permeability, which is a determining factor in making production decisions in the petroleum industry. Compared with NMR logging tools, induced polarization has several advantages, such as a deep depth of investigation and a high signal-to-noise ratio. The purpose of this paper is to establish an appropriate model using induced polarization to estimate the permeability. The curve can be modelled as a weighted superposition of exponential Relaxations. The plot of weight versus the Relaxation Time constant is defined as the Relaxation Time Spectrum. Induced-polarization decay-curve measurements were performed on 123 samples from the Daqing oilfield using a four-electrode technique. A singular-value decomposition method was used to transform the induced-polarization decay data into a Spectrum. Different models to estimate the permeability were discussed. The results of the research indicate that the induced-polarization measurements greatly improve the statistical significance of permeability correlations. Compared with the traditional forms, AΦ C and AF C , the forms, AT B Φ C and AT B F C , have lower error factors, where T, Φ and F are the geometric mean Time constant of the induced-polarization Relaxation Time Spectrum, the porosity and the resistivity formation factor, respectively, and A, B and C are constants. The mean Time constant is the decisive parameter in the permeability estimation and it is not completely independent of the resistivity formation factor. The additional use of the porosity and the resistivity formation factor leads to an appreciable improvement. It is concluded that this new model will make it possible to estimate the permeability of a shaly sand reservoir downhole.
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Determining capillary-pressure curve, pore-size distribution, and permeability from induced polarization of shaley sand
GEOPHYSICS, 2006Co-Authors: Maosong Tong, Weinan Wang, Yizhong JiangAbstract:An appropriate form of induced polarization (IP) acts as a bridge between the structure of a water-saturated core plug and its transport properties. The induced-polarization decay curves of natural rocks can be modeled as a weighted superposition of exponential Relaxations. A singular-value decomposition method makes it possible to transform the induced-polarization decay data of the shaley sands into Relaxation-Time Spectrum, defined as plot of weight versus the Relaxation-Time constant. We measured the induced-polarization decay curves of core samples from a formation of Daqing oil field using a four-electrode method. The decay curves were transformed to Relaxation-Time spectra that were used to estimate the capillary-pressure curves, the pore-size distribution, and the permeability of the shaley sands. The results show that salinity ranges from 1g∕liter to 20 g∕liter have little effect on the IP Relaxation-Time spectra. A pseudocapillary pressure curve can be derived from the IP Relaxation-Time spectru...
Maurizio Furlani - One of the best experts on this subject based on the ideXlab platform.
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resolving distribution of Relaxation Times in poly propylene glycol on the crossover region
arXiv: Soft Condensed Matter, 2004Co-Authors: Enis Tuncer, Maurizio Furlani, Bengterik MellanderAbstract:In this paper, a recently developed numerical technique [{\em Tuncer E and Guba{\'n}ski S M, IEEE Trans Diel El Insul {\bf 8}(3)(2001) 310-320}] is applied to poly(propylene glycol) complex dielectric data to extract more information about the molecular Relaxation processes. The method is based on a constrained-least-squares (\clsq) data fitting procedure together with the Monte Carlo (\mc) method. We preselect the number of Relaxation Times with no {\em a-priori} physical assumption, and use the Debye single Relaxation as ``kernel'', then the obtained weighting factors at each \mc step from the \clsq method builds up a Relaxation Time Spectrum. When the analysis is repeated for data at different temperatures a {\em Relaxation-image} is created. The obtained Relaxation are analyzed using the Lorentz (Cauchy) distribution, which is a special form of the L{\'e}vy statistics. In the present report the $\beta$ and $\alpha$ Relaxations are resolved for the \ppg. A comparison of the Relaxations to those earlier reported in the literature indicate that the presented method provides additional information compared to methods based on empirical formulas. The distribution of Relaxation Times analysis is especially useful to probe the crossover region where the $\alpha$- and $\beta$- Relaxations merge and the results show that the Relaxation after the crossover region at higher temperatures is Arrhenius-type as the $\beta$-Relaxation. Moreover, this Relaxation is more likely to be the continuation of the $\beta$-Relaxation, but with a different activation energy.
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resolving distribution of Relaxation Times in poly propylene glycol on the crossover region
Journal of Applied Physics, 2004Co-Authors: Enis Tuncer, Maurizio Furlani, Bengterik MellanderAbstract:In this article, a recently developed numerical technique [E. Tuncer and S. M. Gubanski, IEEE Trans. Dielectr. Electr. Insul. 8, 310 (2001)] is applied to poly(propylene glycol) (PPG) complex dielectric data to extract more information about the molecular Relaxation processes. The method is based on a constrained-least-squares (C–LSQ) data fitting procedure together with the Monte Carlo method. We preselect the number of Relaxation Times with no a priori physical assumption, and use the Debye single Relaxation as “kernel,” then the obtained weighting factors at each MC step from the C–LSQ method builds up a Relaxation Time Spectrum. When the analysis is repeated for data at different temperatures a Relaxation image is created. The obtained Relaxation are analyzed using the Lorentz (Cauchy) distribution, which is a special form of the Levy statistics. In the present report the β and α Relaxations are resolved for the PPG. A comparison of the Relaxations to those earlier reported in the literature indicate ...