Diffusion In Mixtures Research Articles

Experimental Mixed-Gas Permeability, Sorption and Diffusion of CO₂-CH₄ Mixtures in 6FDA-mPDA Polyimide Membrane: Unveiling the Effect of Competitive Sorption on Permeability Selectivity.

The nonideal behavior of polymeric membranes during separation of gas mixtures can be quantified via the solution-diffusion theory from experimental mixed-gas solubility and permeability coefficients. In this study, CO2-CH4 mixtures were sorbed at 35 °C in 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA)-m-phenylenediamine (mPDA)—a polyimide of remarkable performance. The existence of a linear trend for all data of mixed-gas CO2 versus CH4 solubility coefficients—regardless of mixture concentration—was observed for 6FDA-mPDA and other polymeric films; the slope of this trend was identified as the ratio of gas solubilities at infinite dilution. The CO2/CH4 mixed-gas solubility selectivity of 6FDA-mPDA and previously reported polymers was higher than the equimolar pure-gas value and increased with pressure from the infinite dilution value. The analysis of CO2-CH4 mixed-gas concentration-averaged effective diffusion coefficients of equimolar feeds showed that CO2 diffusivity was not affected by CH4. Our data indicate that the decrease of CO2/CH4 mixed-gas diffusion, and permeability selectivity from the pure-gas values, resulted from an increase in the methane diffusion coefficient in mixtures. This effect was the result of an alteration of the size sieving properties of 6FDA-mPDA as a consequence of CO2 presence in the 6FDA-mPDA film matrix.

Occupancy Dependency of Maxwell-Stefan Diffusivities in Ordered Crystalline Microporous Materials.

Molecular dynamics simulation data for a variety of binary guest mixtures (H2/CO2, Ne/CO2, CH4/CO2, CO2/N2, H2/CH4, H2/Ar, CH4/Ar, Ar/Kr, Ne/Ar, CH4/C2H6, CH4/C3H8, C2H6C3H8, CH4/nC4H10, and CH4/nC5H11) in zeolites (MFI, BEA, ISV, FAU (all-silica), NaY, NaX, LTA, CHA, DDR) and metal–organic frameworks (MOFs) (IRMOF-1, CuBTC, MgMOF-74) show that the Maxwell–Stefan (M–S) diffusivities, Đ1, Đ2, Đ12, are strongly dependent on the molar loadings. The main aim of this article is to develop a fundamental basis for describing the loading dependence of M–S diffusivities. Using the ideal adsorbed solution theory, a thermodynamically rigorous definition of the occupancy, θ, is derived; this serves as a convenient proxy for the spreading pressure, π, and provides the correct metric to describe the loading dependence of diffusivities. Configurational-bias Monte Carlo simulations of the unary adsorption isotherms are used for the calculation of the spreading pressure, π, and occupancy, θ. The M–S diffusivity, Đi, of either constituent in binary mixtures has the same value as that for unary diffusion, provided the comparison is made at the same θ. Furthermore, compared at the same value of θ, the M–S diffusivity Đi of any component in a mixture does not depend on it partner species. The Đi versus θ dependence is amenable to simple interpretation using lattice-models. The degree of correlations, defined by the ratio Đ1/Đ12, that characterizes mixture diffusion shows a linear increase with occupancy θ, implying that correlations become increasingly important as pore saturation conditions are approached.

The effect of the secondary air injection on the gas–solid flow characteristics in the circulating fluidized bed

The design and operation of the secondary air (SA) have a great influence on the axial distribution of particles, the structure of the redox atmosphere, and the gas–solid mixture diffusion in the circulating fluidized bed (CFB) boiler. In this paper, the effects of the SA on the gas–solid flow in the CFB boiler, such as the axial particle distribution and the circulating rate were studied systematically through experimental analysis. All experiments were carried out under the ambient temperature and atmospheric pressure, and quartz sand was selected as the bed material in the 4.5m high CFB test rig made of Plexiglas. The results showed that the SA whose capability to carry particle is affected by the particle concentration at the SA injection port, has a weaker effect on the entrainment of particles than the primary air (PA). The particle concentration in the dense phase zone mainly depends on the PA rate. The increasing of the secondary air ratio (SAR) may lead to the accumulation of particles in the dense phase zone. In addition, one transitional state was found in the transition zone. The variation of particle concentration in the transition zone with the increasing of the SAR is determined by the magnitude of the particle concentration at the SA injection port. The circulating rate decreased with the increasing of SAR or the SA injection height. The effect of the SA injection on the circulating rate in a circulating fluidized bed can be predicted by a modified model with the dimensionless parameters.

Molecular simulations of COFs, IRMOFs and ZIFs for adsorption-based separation of carbon tetrachloride from air

Covalent organic frameworks (COFs), metal organic frameworks (MOFs) and zeolitic imidazolate frameworks (ZIFs) have been widely studied in gas separation applications due to their large surface areas, high pore volumes, tunable pore sizes and chemical stabilities. In this study, separation performances of 153 COFs, 14 IRMOFs and 8 ZIFs were assessed for efficient removal of carbon tetrachloride (CCl4) from CCl4/Ar, CCl4/N2, CCl4/O2 mixtures at 298 K and infinite dilution. The top performing three materials in each group, namely, borazine-linked polymer (BLP-2H-AA), IRMOF-11 and ZIF-6 were identified. Single-component, binary mixture and quaternary mixture adsorption isotherms of argon (Ar), CCl4, nitrogen (N2) and oxygen (O2) in these materials were computed at 298 K and various total pressures from 10−3 to 1.5 × 104 kPa. Mixture adsorption selectivities and separation potentials were then calculated and the effect of relative humidity on the performance of adsorption-based CCl4 separation was examined. Single-component and quaternary mixture diffusion coefficients of Ar, CCl4, N2 and O2 were finally computed. Our results showed that ZIF-6 exhibits the highest adsorption selectivity and the highest separation potential for CCl4/Ar, CCl4/N2 and CCl4/O2 mixtures, followed by IRMOF-11 and BLP-2H-AA. Results of this computational study will be highly useful to identify the promising materials for removal of CCl4 from air.

A mixture theory-based concrete corrosion model coupling chemical reactions, diffusion and mechanics

A 3-D continuum mixture model describing the corrosion of concrete with sulfuric acid is built. Essentially, the chemical reaction transforms slaked lime (calcium hydroxide) and sulfuric acid into gypsum releasing water. The model incorporates the evolution of chemical reaction, diffusion of species within the porous material and mechanical deformations. This model is applied to a 1-D problem of a plate-layer between concrete and sewer air. The influx of slaked lime from the concrete and sulfuric acid from the sewer air sustains a gypsum creating chemical reaction (sulfatation or sulfate attack). The combination of the influx of matter and the chemical reaction causes a net growth in the thickness of the gypsum layer on top of the concrete base. The model allows for the determination of the plate layer thickness h=h(t) as function of time, which indicates both the amount of gypsum being created due to concrete corrosion and the amount of slaked lime and sulfuric acid in the material. The existence of a parameter regime for which the model yields a non-decreasing plate layer thickness h(t) is identified numerically. The robustness of the model with respect to changes in the model parameters is also investigated.

Investigation of effect of temperature on water vapor diffusing into asphalt mixtures

This study investigated the effect of temperature on Phase I water vapor diffusion in asphalt mixtures. A test protocol with a series of Phase I water vapor diffusion tests was designed and performed on hot mix asphalt specimens and fine aggregate mixture specimens. A Gravimetric Sorption Device was utilized to perform the diffusion tests on three replicate specimens of each mixture type at five temperatures. A relative humidity differential was established between the inside and the outside of the test specimen and drove water vapor to diffuse into the specimen until reaching equilibrium. The mass of the test specimen was continuously measured at a frequency of every 5 s using the magnetic suspension balance. The mass of water molecules diffused into the specimen at any time point was calculated to be the measured mass of the specimen at that time point less the initial weight of the specimen.A previously developed 3-D diffusion model was applied to the test data of all replicate specimens to determine the Phase I water vapor diffusivities and the moisture retention capabilities per unit mass under only water vapor pressure at various temperatures. These two parameters were converted into the corresponding values under 1 atmosphere, which were increasing with the increase in temperature. It was found that water vapor diffused into the asphalt mixtures at a significantly lower speed under 1 atmosphere than under only water vapor pressure. It was also observed that an asphalt mixture had a much smaller moisture retention capability per unit mass under 1 atmosphere than under only water vapor pressure.The Arrhenius equation was selected based on theoretical justification to quantify the effects of temperature on diffusivities and moisture retention capabilities per unit mass. Excellent goodness of model fit was achieved for every replicate specimen with an R2 value larger than 0.95. The Arrhenius equation was demonstrated to be an appropriate theoretical model that was able to accurately characterize the temperature dependency of both diffusivities and moisture retention capabilities per unit mass.

Effect of metallic waste addition on the electrical, thermophysical and microwave crack-healing properties of asphalt mixtures

This paper aims to evaluate the effect of metallic waste addition on the electrical, thermophysical and microwave crack-healing properties of asphalt mixtures. With this purpose, asphalt mixtures with two different types of metallic waste, steel wool fibres and steel shavings, added in four different contents, were tested. Electrical and thermophysical properties of asphalt mixture specimens with, and without, metallic waste were measured. The spatial distribution of the metallic waste inside the asphalt mixture samples was evaluated by using X-ray computed tomography. In addition, crack-healing properties of asphalt samples using microwave radiation heating were assessed at two different healing times, 30 s and 40 s. To quantify the efficiency of the healing process, five healing cycles were carried out for each asphalt sample. The main results showed that asphalt mixtures with shavings presented lower air void contents than mixtures with fibres. Moreover, fibres produced an increase in the electrical conductivity of the mixtures because long fibres in the mixtures form electrically conductive channels. In contrast, shavings did not have significant effect on the electrical properties of the mixtures. Likewise, it was proven that metallic waste reduced the thermal conductivity and the specific heat capacity of asphalt mixtures. Conversely, shavings decreased the thermal diffusivity of asphalt mixtures regardless of their content. Overall, it was found that the healing level reached by the asphalt mixtures tested by microwave radiation depends on the healing time and the type and content of metallic waste used. CT-scans results proved that the spatial distribution of metallic waste inside the asphalt mixture samples was not uniform and played an important role in the asphalt self-healing properties using microwave radiation heating.

Interplay of structure and diffusion in ternary liquid mixtures of benzene + acetone + varying alcohols

The Fick diffusion coefficient matrix of ternary mixtures containing benzene + acetone + three different alcohols, i.e., methanol, ethanol, and 2-propanol, is studied by molecular dynamics simulation and Taylor dispersion experiments. Aiming to identify common features of these mixtures, it is found that one of the main diffusion coefficients and the smaller eigenvalue do not depend on the type of alcohol along the studied composition path. Two mechanisms that are responsible for this invariant behavior are discussed in detail, i.e., the interplay between kinetic and thermodynamic contributions to Fick diffusion coefficients and the presence of microscopic heterogeneities caused by hydrogen bonding. Experimental work alone cannot explain these mechanisms, while present simulations on the molecular level indicate structural changes and uniform intermolecular interactions between benzene and acetone molecules in the three ternary mixtures. The main diffusion coefficients of these ternary mixtures exhibit similarities with their binary subsystems. Analyses of radial distribution functions and hydrogen bonding statistics quantitatively evidence alcohol self-association and cluster formation, as well as component segregation. Furthermore, the excess volume of the mixtures is analyzed in the light of intermolecular interactions, further demonstrating the benefits of the simultaneous use of experiment and simulation. The proposed framework for studying diffusion coefficients of a set of ternary mixtures, where only one component varies, opens the way for further investigations and a better understanding of multicomponent diffusion. The presented numerical results may also give an impulse to the development of predictive approaches for multicomponent diffusion.

On the impact of the ISS reboosting maneuvers during thermodiffusion experiments of ternary liquid systems: Pure diffusion

In the present study, the effects of reboosting maneuvers on the diffusion process during the thermodiffusion experiments known as Diffusion and thermodiffusion Coefficients Measurements in ternary liquid mIXtures (DCMIX) are analyzed. These experiments have systematically conducted in the International Space Station (ISS). Six different compositions of a 1,2,3,4-TetraHydroNaphtalene (THN), IsoButylBenzene (IBB) and n-Dodecane (nC12) mixture have been studied by means of numerical simulations. Real acceleration levels have been used to compute the unsteady buoyancy term in the momentum equation. Different gravity scenarios have been considered by changing both the intensity and the duration of the reboosting as well as its orientation, parallel or perpendicular to the concentration gradients. In these thermodiffusion experiments, the different components of the mixture separate in a parallelepipedic Soret cell, with a constant externally imposed temperature gradient between two opposite walls. When the temperature and concentration distributions reach the steady state, and consequently linear concentration profiles between hot and cold walls are achieved, the temperature difference is switched off and the components of the mixture diffuse until uniform concentration distributions are obtained. The present simulations only reproduce this last pure diffusive part of the thermodiffusion experiment. Results show that when a reboosting occurs, errors in the obtaining of the diffusion coefficients arise because of the convection generated. The lower values of the diffusion coefficient show a larger error since they are more sensitive to disturbances. The maximum error is obtained when the acceleration is acting perpendicular to the concentration gradient, which is the most harmful orientation.

Development of a three-dimensional diffusion model for water vapor diffusing into asphalt mixtures

Water vapor diffusion in asphalt mixtures has been investigated to develop water vapor diffusion models that predict the diffusivities of water vapor in asphalt mixtures. However, even the most comprehensive diffusion model available in the literature was not rigorously derived in the three-dimensional (3-D) coordinates but formulated by simply summing up the diffusion models for different directions. This study developed a closed-form 3-D diffusion model for Phase I water vapor diffusion in asphalt mixtures. The developed model was formulated through rigorous derivations originated from Fick’s second law in cylindrical coordinates. The final formulation was a discrete model with infinite terms.The developed model was applied to the data of Phase I water vapor diffusion tests performed on two types of asphalt mixtures at 20 °C using the Gravimetric Sorption Device. The initial relative humidity (RH) inside the test specimen was approximately 0% since the measuring cell where the specimen was placed was pre-vacuumed. The RH outside of the specimen was maintained at 51.51% throughout the test. The weight of the specimen was continuously measured to determine the mass of water molecules diffused into the specimen at different diffusion time points. The test data of every replicate specimen were fitted using the first 36 terms retained in the developed 3-D diffusion model in order to reduce computational efforts. A satisfied level of goodness of model fit was achieved with an R2 value larger than 0.97. The model parameters were determined during model fitting, including the diffusivities of the Phase I water vapor diffusion in asphalt mixtures and the moisture retention capability of each specimen per unit mass. These determined parameters of the hot mix asphalt specimens (HMA) were significantly larger than those of the fine aggregate mixture specimens, which should be attributed to the larger air void contents of the HMA specimens.

Effect of noise on measurements of diffusivity in transparent liquid mixtures by digital speckle photography

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.

Diffusion of gas mixtures in the sI hydrate structure.

Replacing methane with carbon dioxide in gas hydrates has been suggested as a way of harvesting methane, while at the same time storing carbon dioxide. Experimental evidence suggests that this process is facilitated if gas mixtures are used instead of pure carbon dioxide. We studied the free energy barriers for diffusion of methane, carbon dioxide, nitrogen, and hydrogen in the sI hydrate structure using molecular simulation techniques. Cage hops between neighboring cages were considered with and without a water vacancy and with a potential inclusion of an additional gas molecule in either the initial or final cage. Our results give little evidence for enhanced methane and carbon dioxide diffusion if nitrogen is present as well. However, the inclusion of hydrogen seems to have a substantial effect as it diffuses rapidly and can easily enter occupied cages, which reduces the barriers of diffusion for the gas molecules that co-occupy a cage with hydrogen.

Evaporation-induced moisture damage of asphalt mixtures: Microscale model and laboratory validation

Moisture damage is a major source of pavement distress and may cause premature failure. In this study, moisture damage due to evaporation was investigated. A microscale finite-element model coupled with comprehensive laboratory testing was developed to simulate and validate the effect of evaporation-induced moisture damage on asphalt mixture load bearing characteristics on indirect tensile (IDT) strength test. In the proposed model, cohesive zone method (CZM) was used to address crack initiation and development at the aggregate-mastic interface. Quadratic nominal strain and BK exponential damage progress curve were considered for failure due to interaction of shear and normal forces. Fick’s first law was incorporated into the model to simulate moisture diffusion in asphalt mixtures after hours of curing with saturated cold evaporation. Several tests were carried out to derive mechanical and moisture-related input parameters for the model. These tests included an static creep test on mastic, single-edge notch beam (SENB) on asphalt mixtures, and an evaporation diffusion coefficient test on aggregates and mastic. Appropriate moisture-dependent properties were assigned to mastic and aggregate-mastic interface. For laboratory validation, nine samples were fabricated and IDT strength test was performed on them. Samples were cured for 192, 456, and 672 h and tested at loading rates of 0.05, 0.075, and 0.1 mm/s. Comparison of load–displacement plots obtained from laboratory tests and model results showed a descent match in terms of peak load and plot shape. Analysis of factors influencing IDT strength revealed that aggregate-mastic adhesion had a higher contribution to strength of samples compared to mastic cohesion.

Thermal, Mutual, and Self-Diffusivities of Binary Liquid Mixtures Consisting of Gases Dissolved in n-Alkanes at Infinite Dilution.

In the present study, dynamic light scattering (DLS) experiments and molecular dynamics (MD) simulations were used for the investigation of the molecular diffusion in binary mixtures of liquids with dissolved gases at macroscopic thermodynamic equilibrium. Model systems based on the n-alkane n-hexane or n-decane with dissolved hydrogen, helium, nitrogen, or carbon monoxide were studied at temperatures between 303 and 423 K and at gas mole fractions below 0.06. With DLS, the relaxation behavior of microscopic equilibrium fluctuations in concentration and temperature is analyzed to determine simultaneously mutual and thermal diffusivity in an absolute way. The present measurements document that even for mole gas fractions of 0.007 and Lewis numbers close to 1, reliable mutual diffusivities with an average expanded uncertainty ( k = 2) of 13% can be obtained. By use of suitable molecular models for the mixture components, the self-diffusion coefficient of the gases was determined by MD simulations with an averaged expanded uncertainty ( k = 2) of 7%. The DLS experiments showed that the thermal diffusivity of the studied systems is not affected by the dissolved gas and agrees with the reference data for the pure n-alkanes. In agreement with theory, mutual diffusivities and self-diffusivities were found to be equal mostly within combined uncertainties at conditions approaching infinite dilution of the gas. Our DLS and MD results, representing the first available data for the present systems, reveal distinctly larger mass diffusivities for mixtures containing hydrogen or helium compared to mixtures containing nitrogen or carbon monoxide. On the basis of the broad range of mass diffusivities of the studied gas-liquid systems covering about 2 orders of magnitude from about 10-9 to 10-7 m2·s-1, effects of the solvent and solute properties on the temperature-dependent mass diffusivities are discussed. This contributed to the development of a simple semiempirical correlation for the mass diffusivity of the studied gases dissolved in n-alkanes of varying chain length at infinite dilution as a function of temperature. The generalized expression requiring only information on the kinematic viscosity and molar mass of the pure solvent as well as the molar mass and acentric factor of the solute represents the database from this work and further literature with an absolute average deviation of about 11%.

Water vapor passing through asphalt mixtures under different relative humidity differentials

Water vapor diffusion in a newly constructed asphalt pavement consists of water vapor accumulating toward the asphalt layer (Phase I) and water vapor passing through the asphalt layer (Phase II). The water vapor diffusion in Phase I under different relative humidity (RH) differentials has been investigated and can be found elsewhere in literature. However, it remains unclear whether the RH differential would affect the diffusion flux and diffusivity of the water vapor passing through the asphalt layer in Phase II. This study investigated the Phase II water vapor diffusion in asphalt mixtures under a variety of RH differentials. Experimental setups were designed and assembled for the Phase II water vapor diffusion experiments. Distilled water, saturated MgCl2 solution, saturated NaBr solution, and saturated KCl solution were stored in containers to provide the RH level of 100%, 36.5%, 62%, and 87%, respectively, under the asphalt mixture specimens that were sealed on top of these containers. The experimental setups were conditioned in environmental chambers to maintain a constant test temperature of 20 ± 0.5 °C and specific RH levels to establish the RH differentials between the air above and below the asphalt mixture specimen. The weight loss of the experimental setup was monitored three times a day using a high-precision scale.A linear relationship was identified between the RH differential and the diffusion flux of the water vapor in Phase II diffusion, which demonstrated that the Phase II water vapor diffusion followed Fick’s first law of diffusion. The calculated water vapor diffusivities in Phase II diffusion were significantly larger than those in Phase I diffusion and were independent of the variation of the RH differential between the air above and below the asphalt mixture specimen.

Thermodiffusion in Ternary Mixtures of Water/Ethanol/Triethylene Glycol: First Report on the DCMIX3-Experiments Performed on the International Space Station

We report on thermodiffusion experiments conducted on the International Space Station ISS during fall 2016. These experiments are part of the DCMIX (Diffusion and thermodiffusion Coefficients Measurements in ternary Mixtures) project, which aims at establishing a reliable data base of non-isothermal transport coefficients for selected ternary liquid mixtures. The third campaign, DCMIX3, focuses on aqueous systems with water/ethanol/triethylene glycol as an example, where sign changes of the Soret coefficient have already been reported for certain binary subsystems. Investigations have been carried out with the SODI (Selectable Optical Diagnostics Instrument) instrument, a Mach-Zehnder interferometer set up inside the Microgravity Science Glovebox in the Destiny Module of the ISS. Concentration changes within the liquids have been monitored in response to an external temperature gradient using phase-stepping interferometry. The complete data set has been made available in spring 2017. Due to additionally available measurement time, it was possible to collect a complete data set at 30∘C and an almost complete data set at 25∘C, which significantly exceeds the originally envisaged measurements at a single temperature only. All samples could be measured successfully. The SODI instrument and the DCMIX experiments have proven reliable and robust, allowing to extract meaningful data even in case of unforeseen laser instabilities. First assessments of the data quality have revealed six out of 31 runs with some problems in image contrast and/or phase step stability that will require more sophisticated algorithms. This publication documents all relevant parameters of the conducted experiments and also events that might have an influence on the final results. The compiled information is intended to serve as a starting point for all following data evaluations.

Microscopic Theory of Coupled Slow Activated Dynamics in Glass-Forming Binary Mixtures.

The Elastically Collective Nonlinear Langevin Equation theory for one-component viscous liquids and suspensions is generalized to treat coupled slow activated relaxation and diffusion in glass-forming binary sphere mixtures of any composition, size ratio, and interparticle interactions. A trajectory-level dynamical coupling parameter concept is introduced to construct two coupled dynamic free energy functions for the smaller penetrant and larger matrix particle. A two-step dynamical picture is proposed where the first-step process involves matrix-facilitated penetrant hopping quantified in a self-consistent manner based on a temporal coincidence condition. After penetrants dynamically equilibrate, the effectively one-component matrix particle dynamics is controlled by a new dynamic free energy (second-step process). Depending on the time scales associated with the first- and second-step processes, as well as the extent of matrix-correlated facilitation, distinct physical scenarios are predicted. The theory is implemented for purely hard-core interactions, and addresses the glass transition based on variable kinetic criteria, penetrant-matrix coupled activated relaxation, self-diffusion of both species, dynamic fragility, and shear elasticity. Testable predictions are made. Motivated by the analytic ultralocal limit idea derived for pure hard sphere fluids, we identify structure-thermodynamics-dynamics relationships. As a case study for molecule-polymer thermal mixtures, the chemically matched fully miscible polystyrene-toluene system is quantitatively studied based on a predictive mapping scheme. The resulting no-adjustable-parameter results for toluene diffusivity and the mixture glass transition temperature are in good agreement with experiment. The theory provides a foundation to treat diverse dynamical problems in glass-forming mixtures, including suspensions of colloids and nanoparticles, polymer-molecule liquids, and polymer nanocomposites.

Remote sensing image magnification study based on the adaptive mixture diffusion model

In this paper, we propose an adaptive remote sensing image magnification approach. First, an edge stopping function is added to the regularization term of the self-snake model to produce the improved self-snake model, which has a stronger edge-preservation ability. In addition, according to the image gradient information, we put forward a strictly monotonically increasing weight function, which is used to discriminate between edge regions and flat regions. Finally, the adaptive remote sensing image magnification method, which synthesizes the improved self-snake model and Tikhonov regularization by the new weight function is proposed. The proposed model can adaptively adjust the weighting to determine which part plays a more important role in the current state. This model can well protect the edge and texture information of remote sensing images and effectively remove the noise. Experimental results on test images efficiently demonstrate the good performance of the proposed model in terms of both speed and accuracy.

The effect of alcohols as the third component on diffusion in mixtures of aromatics and ketones

With laboratory and numerical work, we demonstrate that one of the main diffusion coefficients and the smaller eigenvalue of the Fick diffusion matrix are invariant to the number of methylene groups of the alcohol in ternary mixtures composed of an aromatic (benzene), a ketone (acetone) and one of three different alcohols (methanol, ethanol or 2-propanol). A critical analysis of the relationship between the kinetic and thermodynamic contributions to the diffusion coefficients allows us to explain this intriguing behaviour of this class of mixture. These findings are reflected by the diffusive behaviour of the according binary subsystems. Our approach provides a promising systematic framework for future investigations into the important and challenging problem of transport diffusion in multicomponent liquids.

Composition dependent transport diffusion in non-ideal mixtures from spatially resolved nuclear magnetic resonance spectroscopy.

Nuclear magnetic resonance (NMR) spectroscopy is a well-established technique for the measurement of intra-diffusion coefficients. Recently, such information has been used as a basis of predictive models to extrapolate to the Fick diffusion coefficient of liquid mixtures. The present work presents a new approach to directly access the Fick diffusion coefficient by spatially resolved NMR experiments. The Fick diffusion coefficient of the binary mixture TEA/H2O was determined at two temperatures, 283.2 K and 275.2 K. The results are consistent with values previously reported either from optical experiments or predictive Darken-type models developed for this system. The proposed methodology adds high-resolution NMR to the toolbox for the study of the transport diffusion of multicomponent mixtures. It is, however, still limited to mixtures with liquid-liquid equilibrium phase separation.