Investigation of high-efficiency Wireless Power Transfer criteria of resonantly-coupled loops and dipoles through analysis of the figure of merit

The efficiency of a Wireless Power Transfer (WPT) system is greatly dependent on both the geometry and operating frequency of the transmitting and receiving structures. By using Coupled Mode Theory (CMT), the figure of merit is calculated for resonantly-coupled loop and dipole systems. An in-depth analysis of the figure of merit is performed with respect to the key geometric parameters of the loops and dipoles, along with the resonant frequency, in order to identify the key relationships leading to high-efficiency WPT. For systems consisting of two identical single-turn loops, it is shown that the choice of both the loop radius and resonant frequency are essential in achieving high-efficiency WPT. For the dipole geometries studied, it is shown that the choice of length is largely irrelevant and that as a result of their capacitive nature, low-MHz frequency dipoles are able to produce significantly higher figures of merit than those of the loops considered. The results of the figure of merit analysis are used to propose and subsequently compare two mid-range loop and dipole WPT systems of equal size and operating frequency, where it is shown that the dipole system is able to achieve higher efficiencies than the loop system of the distance range examined.

Dancing, skating and sex: action and text in the digital age

This paper explores the relationship between discourse and action in practices involved in making and consuming texts. Texts are produced through the process of ‘entextualization’ in which strips of action and discourse are extracted from their original contexts and recontextualized into other situations. Different technologies for turning actions into texts affect the kinds of social actions and social identities that are made possible both at moments of entextualization and at future moments of recontextualization. In particular, I focus on how digital technologies affect the practices and participation structures around entextualization. Digital photography and video have had a profound effect on social practices and relationships around the making of texts. Specifically, they have made processes of entextualization more immediate, more contingent and more communal. Implications of these features of digital text making are discussed in light of previous work on literacy and orality.