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.

The Rilke of Ruth Speirs: new poems, Duino Elegies, Sonnets to Orpheus & others

Rainer Maria Rilke (1875-1926) is universally recognized as among the most important twentieth-century German-language poets. Here, for the first time, are all the surviving translations of his poetry made by Ruth Speirs (1916-2000), a Latvian exile who joined the British literary community in Cairo during World War Two, becoming a close friend of Lawrence Durrell and Bernard Spencer. Though described as ‘excellent’ and ‘the best’ by J. M. Cohen on the basis of magazine and anthology appearances, copyright restrictions meant that during her lifetime, with the exception of a Cairo-published Selected Poems (1942), Speirs was never to see her work gathered between covers and in print. This volume, edited by John Pilling and Peter Robinson, brings Speirs’ translations the belated recognition they deserve. Her much-revised and considered versions are a key document in the history of Rilke’s Anglophone dissemination. Rhythmically alive and carefully faithful, they give a uniquely mid-century English accent to the poet’s extraordinary German, and continue to bear comparison with current efforts to render his tenderly taxing voice.