PubMed · 243004
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R B Norby, L E Freund, B Wagner. 1977. A nurse staffing system based upon assignment difficulty.. https://doi.org/10.1097/00005110-197707090-00001
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A simple computational method for calculating dielectric constants of solvent mixtures based on Redlich-Kister extension was proposed. The model was applied to the experimental dielectric constant of binary and ternary solvent mixtures at fixed and/or various temperatures and showed accurate results. Overall average percentage deviation (OAPD) between calculated and experimental dielectric constants was calculated as an accuracy criterion. The OAPDs for correlative and predictive analyses of dielectric constants in binary solvents at a fixed temperature were 0.56 and 1.42%, respectively. The corresponding values for binary solvents at different temperatures were 1.29 and 1.92%, respectively. The OAPDs for correlative and predictive analyses of dielectric constants of a nonaqueous ternary solvent mixture at various temperatures were 1.61 and 3.05%. The accuracy of the proposed models has also been compared with those of previously published models and results showed that the proposed models were superior and capable of providing more accurate results.
We present a simple analytical solution for one-dimensional steady heat transfer with convection and conduction through a multilayer system such as a vadose zone. We assume that each layer is homogeneous and has a constant thermal diffusivity. The mass/heat flow direction is perpendicular to the layers, and the mass flow rate is a constant. The analytical solution presented in this study also assumes constant known temperatures at the two boundaries of the system. Although the analytical solution gives the temperature as a function of a few parameters, we focus on the inverse application to estimate the percolation rate in a vadose zone. Example applications have shown that with reliable field observation data, the solution can be used to determine the percolation rate to high degree of accuracy (e.g., to mm/year). In some other cases, the solution may also be helpful in characterizing potential lateral flow along layer divides.
Osmotic pressure-driven drug release from rubbery polymer matrices in a cylindrical geometry has been shown to produce a period of nearly constant release. In order to explain this behavior and in an effort to produce a tool for device design, a mathematical model of the release was developed. The model was tested by application to literature data of the release of NaI from poly(dimethylsiloxane) cylinders and found to provide good agreement with the data. The model demonstrates that, although there is a decrease in solute concentration as one moves from the exterior to the center of the cylinder, a period of nearly constant release is produced, lasting until about 60% of the initial drug load has been released.