Final Concentration Profile Research Articles

Concentration Profile Measurement of Liquid–Solid Two-Phase Horizontal Pipe Flow Using Ultrasound Doppler

Concentration measurement of multiphase flow is essential to flow assurance and monitoring in industrial processes. The concentration profile is a quantitative parameter to diagnose the multiphase flow states and has drawn wide attention from researchers. An ultrasound Doppler technique is adopted to measure the concentration profile of liquid-solid two-phase horizontal pipe flow. A Bayesian inference based on the Differential Evolution Adaptive Metropolis sampling algorithm is proposed to solve the statistical inversion of the concentration profile. The posterior probability distributions of the solid concentration are sampled, and the final concentration profile is chosen with the maximum a posteriori probability. An experimental platform is built for liquid-solid two-phase flow experiments and ultrasound concentration profile measurement. The measured concentration profiles are verified with a maximum mean absolute error of 8.14%.

Modeling and optimization of the fabrication process of thin-film solar cells by multi-source physical vapor deposition

This work presents a mathematical model describing the thin film formation during the co-evaporation of elements by PVD process for the production of CIGS type thin film photovoltaic cells. We propose a one-dimensional system of cross-diffusion Partial Differential Equations (PDEs) defined in a time-dependent space domain and introduce a numerical scheme for the discretization of the system. We calibrate our model on true experimental measurements using a dual approach. Then, in order to achieve certain targeted final concentration profiles, we consider an optimization problem that allows controlling the external atomic fluxes injected during the process. Despite its simplicity, the proposed model shows promising results towards a quantitatively predictive model. For instance, novel atomic fluxes obtained as solutions of the optimization problem could represent alternatives to the classical three-stage process. In this paper, a mathematical model describing the thin film formation during the co-evaporation PVD process for the production of CIGS type thin film photovoltaic cells is proposed.

Steady-state protein focusing in carrier ampholyte based isoelectric focusing: Part I-Analytical solution.

The determination of an analytical solution to find the steady-state protein concentration distribution in IEF is very challenging due to the nonlinear coupling between mass and charge conservation equations. In this study, approximate analytical solutions are obtained for steady-state protein distribution in carrier ampholyte based IEF. Similar to the work of Svensson, the final concentration profile for proteins is assumed to be Gaussian, but appropriate expressions are presented in order to obtain the effective electric field and pH gradient in the focused protein band region. Analytical results are found from iterative solutions of a system of coupled algebraic equations using only several iterations for IEF separation of three plasma proteins: albumin, cardiac troponin I, and hemoglobin. The analytical results are compared with numerically predicted results for IEF, showing excellent agreement. Analytically obtained electric field and ionic conductivity distributions show significant deviation from their nominal values, which is essential in finding the protein focusing behavior at isoelectric points. These analytical solutions can be used to determine steady-state protein concentration distribution for experiment design of IEF considering any number of proteins and ampholytes. Moreover, the model presented herein can be used to find the conductivity, electric field, and pH field.

Numerical simulation of hydrogenation of GaAs at the cooling stage

Evolution of concentration profiles of all types of hydrogen particles, charge carriers, active doping impurity, and distribution of the electric field in the near-surface layer of hydrogenated p-GaAs during cooling the sample after finishing the stage of introduction of hydrogen is simulated. It is shown that the form of final concentration profiles of hydrogen-containing particles and distribution of the intrinsic electric field in the hydrogenated p-GaAs layer depend on the temperature-time mode of cooling the sample. The degree of the effect of the cooling rate on the final state of hydrogenated layer increases as the doping level of semiconductor is decreased. Systematic features of formation of the final state of the hydrogen-crystal system depending on the cooling rate of the sample are presented and discussed.

Imaging the drying of a colloidal suspension

We present an experimental investigation of the drying kinetics seen from inside a sessile droplet laden with a colloidal sol of silica nanoparticles. We use fast, two-color confocal microscopy imaging to quantitatively extract on the one hand the concentration field of the rhodamine-tagged nanosol and on the other hand the velocity field and the mobility field of large, fluorescein-tagged tracers. By changing the initial concentration at which the drop dries up, we propose a method that yields a self-consistent way to obtain the rheology of the sol. Based on these results, we analyse the drying kinetics in terms (i) of flow patterns that include evaporating and Marangoni flows which compete to determine the final concentration profile and (ii) of truncated dynamics that we quantitatively relate to the rheology of the sol.

Investigation of Consolidation-Induced Solute Transport. II: Experimental and Numerical Results

This paper presents an experimental and numerical investigation of consolidation-induced solute transport. Diffusion and large strain consolidation tests were performed on composite specimens of kaolinite clay consisting of an upper uncontaminated layer and a lower layer contaminated with potassium bromide. Experimental measurements of effluent concentration, solute mass outflow, and final concentration profiles were obtained for a variety of initial, boundary, and loading conditions, including unload/reload. Numerical simulations were conducted using a computational model in which solute transport occurs by advection, dispersion, and sorption and is consistent with temporal and spatial variations of porosity and seepage velocity in the consolidating layer. Large strains were taken into account as well as variation of effective diffusion coefficient with porosity and nonlinear nonequilibrium sorption effects. The numerical simulations are in good to excellent agreement with the experimental measurements. Results indicate that, depending on conditions, diffusion and consolidation-induced advection can make important contributions to solute transport and mass outflow. Thus, both mechanisms should be considered for transport analyses involving soft contaminated clays undergoing large volume change. Results also indicate that nonequilibrium sorption effects were not significant for the materials and test conditions used in this study.

A general method for the calculation of segregation profiles in floating zone grown silicon ingots with non-uniform initial distribution of the solute

In polycrystalline silicon analytics segregation effects related to radial non-uniform dopant distributions are of major importance for the interpretation of resistivity data. The determination of dopant concentrations and resistivity profiles in polycrystalline silicon inevitably requires the transformation into a single crystal. Neglecting segregation effects may therefore substantially bias the actual material properties. A tool for the computation of final concentration profiles in floating zone grown ingots with non-uniform initial distributions has been developed, which allows the re-calculation of polysilicon data from single crystal data.

On the capacity of continuous powder classification in a gas-fluidized bed with horizontal sieve-like baffles

Using horizontal sieve-like baffles in fluidized beds increases the tendency of particle mixtures to segregate. This may be utilized to devise a new process for dry classification of particles according to size or density. To predict the capacity of a continuous classification process based on this principle, the segregation rate must be known in addition to the final concentration profile. This paper describes an experimental investigation of this, using a fluidized bed with horizontal sieve-like baffles and an equal density mixture. The experiments confirmed that the baffles increase the particle segregation in the bed, and hence, the purity of the flotsam in the top layer. The capacity of a continuous fluidized bed particle classifier and the effect of particle size on the obtainable segregation are discussed. A first modelling attempt to describe the rate of growth of the lower segregation layer is presented. The mechanistic model for axial particle transport proposed in the literature is only partially successful in explaining the experimental results.

Steady-state concentration distribution of ampholytes in isoelectric focusing in a linear immobilized pH gradient.

The equation of balance between electrophoretic and diffusional mass flows in the steady state of isoelectric focusing is analyzed. To create the pH gradient, a model system composed of only one Immobiline is used. The solution is found for the case of a small sample concentration, but without assumptions about linear "focusing force" and constant (linear) conductivity profiles. The effect of sample concentration on the final concentration profile is also evaluated. At high sample concentrations, it is demonstrated that the steady-state distribution is essentially non-Gaussian and results in a considerably lower concentration maximum as compared with low sample levels.

23] Molecular chaperones and their interactions investigated by analytical ultracentrifugation and other methodologies

Publisher Summary The chapter presents a study related to molecular chaperones and their interactions through analytical ultracentrifugation and other methodologies. After a brief introduction into basic principles of the technique, the chapter presents practical examples to illustrate the ability of the methodology to resolve controversial questions in the chaperone field and discusses some results in the context of other methodologies used to determine quaternary structure. In an analytical ultracentrifugation experiment an analysis is made of the distribution of molecules according to their masses within a field of gravitation. This analysis can also be done using a preparative centrifuge, where the concentration gradient is measured after the run and drop fractionation of the contents of the tubes; however, in this case only final concentration profiles are obtained from a single centrifugation run and sedimentation must occur in the presence of preformed density gradients (for example, of glycerol or sucrose). The chapter discusses that determination of protein quaternary structure should never be based exclusively on relative methods. Only a few methodologies, such as analytical ultracentrifugation techniques, unambiguously deliver molecular masses of homo- or hetero-complexes in solution without the need for arbitrary assumptions. The chapter demonstrates the practicality of investigating the comparably large chaperonin heterocomplexes under equilibrium. The chapter concludes by stating that the investigation of chaperonin-substrate interactions will be a productive field for future analytical ultracentrifugation experiments.

Compound formation effects in computing implantation profiles

During very high dose ion implantation, the influence of high concentrations of the ion species in the substrate makes the calculation of the final concentration profile very difficult. A concentration depth profile modeling program has been written which accounts for the expansion of the substrate due to the interaction of the ion beam atoms with the substrate. Three types of interaction have been considered: (1) weakly interacting mixture, (2) partial reaction and (3) complete compound formation. In addition to the influence of these bulk properties on the ion transport in the substrate, the substrate also influences the sputter loss of the front surface, which distorts the shape of the final profile. The model also contains realistic instantaneous Pearson distribution functions, multilayer substrates, curved substrates and multiple energy-dose implants. The predictions of the code are compared with experimentally determined high dose profiles.

Diffusion of deterrents into a nitrocellulose matrix. An example of diffusion with interaction

AbstractThe diffusion of various concentrations of a deterrent (di‐n‐butyl phthalate) into a spherical, nitroglycerin‐containing nitrocellulose matrix was studied. It was concluded that the final concentration profile could best be explained by a diffusion with interaction mechanism. Based on this mechanism, a method for calculating the depth of deterrent penetration is presented.