Thermodynamics of the system NaF-AIF3: Part VI. revision

Literature data are reviewed to derive enthalpies and entropies of Na₃AlF₆ and NaF, and they are combined with electrochemical and equilibrium data to yield free energies of formation of Na₃AlF₆ from the constituent fluorides. Liquidus data and measurements of the Na content of Al in equilibrium with the melts then enable the calculation of the free energy of formation, enthalpy, and entropy of all mixtures liquid at 1293 K. In stoichiometric Na₃AlF₆ at 1293 K, a_NaF =0.37 and a_{AlF 3} = 4.9 × 10⁻⁴. The activity coefficient of Na in dilute solution in Al is given byRT ln γ_Na = (40 967 + 9.480 T) J. At 1293 K the partial pressure of NaAlF₄ is given by pNaA1F₄/bar = 27a_NaF . a_{Aif 3}- A heavier species— suggested to be NaAl₃F₁₀—is present in the vapor above AlF₃-rich melts.     

Loss of current efficiency in aluminum electrolysis cells

Consideration of the mechanism of loss of current efficiency (CE) leads to a form of equation which is simple, likely to give reasonable extrapolation beyond the range where experimental data are available, and convenient for responding to practical questions. With coefficients generated from plant experiments (performed by others), the equation is log (pct loss of efficiency) = 0.0095 (superheat) -−0.019 (pct A1F₂) − 0.060 (pct LiF) + const where superheat is the difference (in °C) between cell temperature and the pseudo-binary eutectic temperature with A1₂O₃, and pct A1F₃ is excess A1F₃. The coefficient for CaF₂ is zero. The constant is characteristic of the cell design. The question of reconciling the values of the coefficients with literature data on the solubility of Al in cryolite melts and current theories of loss of efficiency is discussed. Formerly Principal Scientist, Kingston Laboratory, Alcan International Ltd., Kingston, ON K7L 5L9, Canada, is retired.     

Uses of fats,fatty oils,and derivatives in the petroleum industry

Conclusion The use of fats, fatty oils, and derivatives is extensive in the petroleum industry to improve its lubricants in their wetting ability or oiliness. Fats and their derivatives serve to carry active elements such as chlorine, sulfur, and phosphorus for the improvement of load-carrying capacity, resistance to oxidation, inhibiting corrosiveness, and preventing wear during use. Greases are compounded from whole fats and fatty acids which serve under suitable conditions to gel lubricating oil and thus fulfill lubricating requirements which the liquid oils cannot themselves satisfy. Greases and their components may be tested for skin hardening in storage by means of an oxygen absorption test which distinguishes between satisfactory and unsatisfactory ingredients and products. Presented in a symposium on the Industrial Applications of Fats & Fatty Acids at the Fall Convention of the American Oil Chemists Society, Chicago, Oct. 1939.     

SOME PHYSICAL PROPERTIES OF CHEMICAL STONEWARE BODIES1

Crushing, transverse and impact strength, thermal expansion, resistance to heat shock, and elasticity were determined for nine commercial chemical stoneware bodies. Although the thermal expansions were not widely different, great variations were obtained for the elasticity and crushing strength values of the various bodies. The elasticity and crushing strength of the more porous bodies were distinctly less than for the more vitreous bodies. The method of making and interpreting the impact test is discussed in detail.     

A limit set stabilization by means of the Port Hamiltonian system approach

A solution to the stabilization problem of a compact set by means of the Interconnection and Damping Assignment Passivity‐Based Control methodology, for an affine nonlinear system, was introduced. To this end, we expressed the closed‐loop system as a Port Hamiltonian system, having the property of almost all their trajectories asymptotically converge to a convenient limit set, except for a set of measure zero. It was carried out by solving a partial differential equation (PDE) or single matching condition, which allows the desired energy level or limit set E to be shaped explicitly. The control strategy was tested using the magnetic beam balance system and the pendulum actuated by a direct current motor (DC‐motor), having obtained satisfactory results. Copyright © 2014 John Wiley & Sons, Ltd.     

Fuzzy Adaptive Control Law for Trajectory Tracking Based on a Fuzzy Adaptive Neural PID Controller of a Multi-rotor Unmanned Aerial Vehicle

International Journal of Control, Automation and Systems - This article presents a fuzzy adaptive control law (FACL) designed for tracking the trajectory of a low-scale unmanned aerial vehicle...