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The formulations of existing free dendritic growth models were compared, and an extended model was proposed that employs a subregular solution model to compute the driving force for dendritic growth without Henrian restrictions. These models were also applied to a Ag-15 mass pct Cu alloy to numerically compare their predictions. Models that address only the thermal, solutal, and curvature supercoolings do not properly account for the interface kinetics, even with modifications with the kinetic partition coefficient and liquidus slope. It is only in models that account for the interfacial driving force, -DG * , that the kinetic supercooling is properly addressed. All of the models in comparison yield numerically similar predictions for the solutal growth regime, but models that employ the kinetic partition coefficient and liquidus slope, but do not address the interfacial driving force, fail to correctly describe the thermal control regime. The solutal-to-thermal transition is characterized by a rapid increase of interfacial driving force, which causes the tip temperature T * to increase with increasing growth rate V. The criterion for the transition stage is given as d lnðÀDG à Þ=d ln V>1.

During electrochemical machining (ECM) of metals, the electrolyte gets polluted by heavy metal ions and compounds. This creates crucial process control problems due to variation in electrical conductivity and is an environmental threat if the solution is discharged without treatment. In this study, an economical, simple multistep treatment system based on ion-exchange was developed to remove metal ions from the polluted electrolyte. We specifically looked at the electrolytic discharge from ECM of copper pieces, which is widely used in biomedical and electronic applications. Three different ion-exchange media were used: (1) a natural zeolite, (2) a special type of adsorbent quantitative filter paper, and (3) a polymer-based synthetic cation-holder resin (Lewatit TP 207) that works well with copper ions. Optimization studies for pH and contact time showed the following: (1) by using zeolite alone, and after 2 h of mixing, 43.2% of Cu2+ could be removed; (2) by using the filter paper alone, and after three times of filtration, 90% of Cu2+ could be removed; and (3) by using Lewatit TP 207 alone, 100% of Cu2+ could be removed. While Lewatit TP 207 allowed for 100% removal of Cu2+, its use alone is costly and troublesome due to constraints from service life and multistep regeneration and conditioning with strong acids and bases, respectively. The most simple and economical scheme for removal of Cu2+ and recycling the electrolyte for reuse was the three-step zeolite-filter-resin treatment system.

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In this study, the Shannon entropies of six different road-profiles ranging from “very good asphalt road” to “dirt road (terrain)” were calculated. Results indicate that each type of road has a well defined entropy value and that the entropies of roads ranging from “very good asphalt” to “dirt road (terrain)” lie on a nearly linear locus. A second approach presented in this paper consists in measuring the sprung mass vertical acceleration of a vehicle running over segments of roads of different qualities and calculating the entropies of the acceleration signals. This procedure has been applied to assess the influence of nonlinear damping and vehicle speed. It has been seen that it is possible to identify the type of the road surface through the calculation of entropy if the vehicle operating parameters are known. Finally, it is observed that the locus of entropy values is concave on the plot of acceleration entropy versus root mean square (RMS) acceleration.