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Showing 1 to 20 of 20 for “"Fick's Law"”.
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Determination of chloride diffusion constants for concretes of differing water to cement ratios and admixtures
… ion diffuses through concrete according to Fick's Law, which is a function of time, a driving concentration, and a diffusion constant. The diffusion constant varies with temperature and the variety of concrete . The research included determination of diffusion constants for six types of …
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Cross-Laminated Timber made of Unmodified and Thermally Modified Yellow-Poplar Lumber
… layers, and moisture-induced strain. Traditional Fick's law models fail to account for these effects, resulting in large prediction errors. The PIDDML model, trained on 11 features including humidity, temperature, and moisture, integrated diffusion and strain data, explicitly accounting for …
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Channeling studies of the location of zinc in gallium-arsenide
… zinc concentration squared in marked contrast to Fick's law which predicts that D is concentration independent. D is also very sensitive to the ambient conditions during diffusion, particularly the arsenic overpressure and the presence of other doping species. Further, heavy zinc doping can …
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Reduced-dimension model for the Rayleigh-Taylor instability in a Hele-Shaw cell
… equations of the system, Stoke's equations and Fick's law, using polynomial trial functions. We discuss the results and conduct a linear stability analysis of the reduced system. We compare the model to a finite element simulation of the full governing equations using COMSOL, and propose an …
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DEVELOPMENT AND IN-SITU CHARACTERIZATION OF BI-LAYERED LAMINATED COMPOSITES FOR ENHANCED MOISTURE BARRIER PERFORMANCE
… based on the principles of 1-dimensional Fick's law of diffusion. The diffusivities were statistically analyzed to determine significant differences between the samples, and the experiment yielded a minimum of 65% reduction in diffusivity across the samples. Furthermore, a thermomechanical …
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Rates of evaporation of small drops at low pressures
… surface must be calculated from the solution to Fick's law of diffusion and the appropriate set of boundary conditions. This was first done in an approximate manner by Langmuir, and later with more accuracy by Bradley, Evans, and Whytlaw-Gray and by Frisch and Collins. In this research, the …
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Channeling studies of the location of zinc in GaAs
… zinc concentration squared in marked contrast to Fick's law which predicts that D is concentration independent. D is also very sensitive to the ambient conditions during diffusion, particularly the arsenic overpressure and the presence of other doping species. Further, heavy zinc doping can …
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Aging of polymeric composites : a literature review
… depending on the aging process. In most cases, Fick's law of diffusion was confirmed as an accurate model for moisture absorption. Temperature fluctuations were always deemed as damaging to composite structures. Due to the haziness still present in current research coupled with the importance of …
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A method for approximating and controlling the distributed parameter model of a MIMO chemical diffusion system
… method for transforming the diffusion equation (Fick's Law) into a finitely-approximated, MIMO, state-space system, by first deriving a matrix of infinite transfer functions. With this state-space system, it is shown that classical control techniques can be applied to manipulate the dynamics as …
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The development of h Homogeneous nucleation rate model for thermoplastic foams based on a molecular partition function and Fickian diffusion
… utilizing a diffusion-based model derived from Fick's law, Additional approaches including a diffusion only based approach, a fluctuation theory based approach, and a lattice model based approach were all unsuccessfully investigated. The predictions obtained from the model have been compared to …
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A study of the decay of acid cationic ion exchange resin
… of the equilibrium through the Mass-Action Law, capacity and resin kinetics. A study, of existing kinetic rigorous modelling methods and in particular the extensively published challenge of the multiple mechanism adsorption process, was undertaken. A rigorous model, that divorces the …
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Evaporation from nanopores : probing interfacial transport
… governed the overall transport instead of Fick's law, especially in the high flux regime. In vapor, we achieved kinetically limited evaporation with an interfacial heat transfer coefficient up to 54 kW/cm² K. We utilized the kinetic theory with the Boltzmann transport equation to model the …
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Dynamic modelling and simulation of the all-vanadium redox flow battery
… side reactions on the basis of mass balance and Fick's law, followed by employing energy balance to investigate the variation in electrolyte temperature as a function of time under different operating conditions and battery structure design. The energy balance is subsequently coupled with the …
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Experimental studies of sorption and transport of moisture in cement based materials with supplementary cementitious materials
… in small paste samples. The results show that Fick's law cannot completely describe the transport process in such small samples and sorption behavior is therefore anomalous with two processes with different time scales. One of these is macro-diffusion into the sample, which takes place on a …
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A viscoelastic hydrodynamic approach to the density fluctuations in classical liquids
… associated with self motions by generalizing the Fick's law with a time-dependent diffusion tensor. To further characterize the underlying modes of time correlation functions outside the hydrodynamic regime, a relaxation-excitation mode analysis is proposed, following the mathematical structure of …
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Evaluation of Moisture Diffusion Theories in Porous Materials
… Several diffusion models in the form of "Fick's Law" including ones based on gradients of water-vapor pressure, chemical potential of water, moisture concentration and activated moisture molecules have been proposed for predicting moisture diffusion through porous materials. However, the …
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Mathematical Modeling, Analysis and Control of Some Infectious Diseases
… consideration. The model is parabolic, since the Fickian diffusion is assumed to be valid. In chapters 2 and 3, we investigate on the spread of two infectious diseases, which differ from each other via different transmission vehicles of the virus. In particular, chapter 2 deals with a new model …
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Crystal growth and nucleation kinetics of diethylenetriammonium hexachlororhodate (III) salt
… proposed by Von Smoluchowski coupled with Fick's law of diffusion and gives a good representation of crystal size. The PFR growth rate supersaturation exponent was 1.13, suggesting a Burton-Cabrera-Frank type growth model, and is indicative of crystal growth from screw dislocations that is …
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Assessing landscape and seasonal controls on CO2 fluxes in a karst sinkhole
Karst landscapes can serve as carbon sinks when carbon dioxide (CO2) reacts with water to form carbonic acid, which then weathers carbonate rocks. However, CO2 can also move through the subsurface via gas diffusion, a process that is not well-understood in karst systems. This study focused on …
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Development of alternating amphiphilic copolymers for targeted delivery applications in cancer
… including a homogeneous kinetic model and a Fick's Law mass transfer model. Significant differences were observed between the experimental results and the predictions of the homogeneous model. The mass transfer modeling, which estimated the increase in reactant and methanol surface …