Vapor-liquid equilibria using the Gibbs energy and the common tangent plane criterion

Phase thermodynamics is often perceived as a difficult subject that many students never become fully comfortable with. The Gibbsian geometrical framework can help students to gain a better understanding of phase equilibria. An exercise to interpret the vapor-liquid equilibrium of a binary azeotropic mixture, using the equilibrium condition based on the common tangent plane criterion (the Gibbs stability test), is presented in this paper. From a T-composition phase diagram for the mixture, the temperature is set at different values: above, intermediate to, and below the boiling temperatures of the pure components, to intersect different regions of the system. Students prepare an Excel spreadsheet where the Gibbs energy of mixing of the vapor and liquid mixtures are calculated and represented over the whole range of compositions and then, apply the Gibbs stability test to ascertain the aggregation state of the system and to calculate the VL phase equilibrium compositions. Finally, Matlab is used to generate the 3D Gibbs energy of mixing surfaces for both phases over the whole range of temperatures which facilitates the geometrical interpretation of the vapor-liquid equilibrium.

Gibbs Energy of Mixing Function: Topological Analysis in Azeotropic Systems

ESAT 2014. 27th European Symposium on Applied Thermodynamics, Eindhoven University of Technology, July 6-9, 2014.

The action cam phenomenon: a new trend in audiovisual production

When the GoPro camera was first put on the market in 2004, it brought about a new generation of ultracompact cameras designed to be attached to the user’s body, and which came to be known as action cams. Their principal characteristics were their tiny size, their high-quality images and a wide-angle, fixed-focal-length lens. This combination has made it much simpler to get spectacular subjective shots with considerable depth of field. The users of this technology now form a whole generation of citizen-filmmakers who produce thousands of videos every day in a novel realistic style dominated by first-person narrative. Their work is principally shared via video platforms like YouTube and Vimeo, which provide instant feedback in the form of millions of views. In this paper we analize the common features of the action cam recording style and we state these videos will bring about a redefinition of the realist visual style. Furthermore, we propose to relate the success of the action cam phenomenon with the cognitive concept of embodiment and argue that the viewer’s mirror neurons copy the real sensations and enable the viewer to experience, virtually and in safety, the same emotions felt by the person actually taking part in the action.