Urban passenger mobility challenges can be sustainably eased with electric trains. However, due to the visual impact, safety and, electrification cost concerns, some routes or section(s) of a route are not electrified. In such cases, battery powered trams present a promising alternative. Rail vehicles are heavy but, they have a low coefficient of rolling friction. Consequently, they draw high power during acceleration as compared to the power demand during cruising. Thus, a high capacity high-voltage traction battery is required to provide accelerating power. To minimise total electrified distance and traction battery size, a battery and accelerating-contact line (BACL) hybrid tram system in which a tram accelerates from a station drawing power from a short contact line and cruises with traction battery is presented. Simulated in MATLAB, the BACL hybrid tram system with 1.8 km total electrified distance has equivalent performance to the conventional battery and contact line hybrid tram system with 12.2 km total electrified distance. Compared to independently battery powered tram, battery size is reduced by 62.5%. Suggested applications for the BACL tram system are on short, fairly flat, idle lines with few stops.
The optical contact-loss measuring system based on the detection of arcing photons uses visible rays in measurement, which is executed only at night because the method's accuracy is reduced by environmental light. This problem can be solved by adopting a new system based on the detection of ultraviolet rays, which is expected to be adopted by The International Electrotechnical Commission in the future. However, the new system has the drawback of being very expensive. This paper reports on a low-priced measurement system developed to address the issue.
Current-dependent resistance observed for complex cuprates Gd1−xPrxBa2Cu3Oy and Nd1−xPrxBa2Cu3Oy with Pr-concentration x ranging from 0 to 0.8 has been investigated in reference to the structural inhomogeneity. At Pr-concentration above the percolation threshold xpc, where the overall superconductivity vanishes, the electrical resistance has been found to considerably depend on the supplied current I. The current dependence is classified into three types, according to the behaviour of the resistance when x is increased: at around xpc the resistance increases with increasing I, and at higher x it becomes independent of I. Finally, at sufficiently high x, the resistance becomes dependent again on I, but changes into a decreasing function of I. A model of this non-ohmic phenomenon has been given in terms of the current distribution when the superconducting network is broken by increasing x.
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