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The Cold War period was widely understood as one of bipolarity with the USA and the USSR as the world's two superpowers, whereas the end of the Cold War led to unipolarity with the US as the world's sole superpower in the 1990s and 2000s. Scholars have debated how to characterize the current international system. [2] [3] [4]
The rate of decrease and the current strength are within the normal range of variation, as shown by the record of past magnetic fields recorded in rocks. The nature of Earth's magnetic field is one of heteroscedastic (seemingly random) fluctuation. An instantaneous measurement of it, or several measurements of it across the span of decades or ...
A block diagram of a bipolar HVDC transmission system, between two stations designated A and B. AC – represents an alternating current network CON – represents a converter valve, either rectifier or inverter, TR represents a power transformer, DCTL is the direct-current transmission line conductor, DCL is a direct-current filter inductor ...
Birkeland currents are also one of a class of plasma phenomena called a z-pinch, so named because the azimuthal magnetic fields produced by the current pinches the current into a filamentary cable. This can also twist, producing a helical pinch that spirals like a twisted or braided rope, and this most closely corresponds to a Birkeland current.
Some researchers use the term magnetricity to describe the manipulation of magnetic monopole quasiparticles in spin ice, [50] [51] [49] [52] in analogy to the word "electricity". One example of the work on magnetic monopole quasiparticles is a paper published in the journal Science in September 2009, in which researchers described the ...
A third line, Bipole 3, was completed in 2018, running from the new Keewatinoow Converter Station along the west side of Lake Manitoba to the new Riel Converter station on the east side of Winnipeg. There are no intermediate switching stations or taps. All three bipolar systems have extensive ground return electrodes to allow use in monopolar mode.
A pair of parallel conductors with current Î 1 and Î 2 flowing on each conductor, which can be decomposed into CM and DM current respectively. Fig. 1. CM and DM Current Illustration on Pair Conductors. As shown in the figure above, the relations between Î 1, Î 2 and modal current are given: Î 1 = Î C + Î D Î 2 = Î C - Î D
The plotted line represents the variation of instantaneous voltage (or current) with respect to time. This cycle repeats with a frequency that depends on the power system. In electrical engineering, three-phase electric power systems have at least three conductors carrying alternating voltages that are offset in time by one-third of the period ...