DC railways and the magnetic fields they produce—the geomagnetic context
DC electric railways produce magnetic fields, not only from the intended traction currents, but also from unintended earth-leakage currents; these fields, particularly those from the leakage currents, are becoming an increasing problem for geomagneticians. This paper introduces the relevant properties of DC-railway traction-power circuits, and the various ways in which earth-leakage currents are produced, and discusses models of how these leakage currents vary along the track and with train position. It describes the geometry of the resultant magnetic fields, and gives the formal algebra for calculating the magnetic field when these leakage currents are known, but also suggests some simple approximations that could be used when the current distribution is not known in detail. This paper also summarises previous relevant papers.
Magnetic fields on British trains.
People on trains can be exposed to static and alternating magnetic fields which are higher than background levels in most homes and many workplaces. Quantification of such exposure may be of interest for epidemiological purposes but it is also important to ensure that exposure guidelines are complied with. This article describes the types of electric trains and trams in use in the UK and the results of measurements of static and alternating magnetic flux density. Many of the data have been supplied by the operators of the systems described. The measurements summarised in this article are indicative of the magnitudes of magnetic field exposures to be encountered on British trains, but without concomitant frequency information, they are not sufficient to allow demonstration of compliance with exposure standards.
Interaction of Formaldehyde and Tetrahydrofolic Acid and Its Relation to the Enzymic Synthesis of Serine
Interaction of Formaldehyde and Tetrahydrofolic Acid and Its Relation to the Enzymic Synthesis of Serine