The drag force can be used to the electrodynamic system's advantage, however, as it creates a varying force in the rails that can be used as a reactionary system to drive the train, without the need for a separate reaction plate, as in most linear motor systems. Laithwaite led development of such "traverse-flux" systems at his Imperial College laboratory.  Alternatively, propulsion coils on the guideway are used to exert a force on the magnets in the train and make the train move forward. The propulsion coils that exert a force on the train are effectively a linear motor: an alternating current through the coils generates a continuously varying magnetic field that moves forward along the track. The frequency of the alternating current is synchronized to match the speed of the train. The offset between the field exerted by magnets on the train and the applied field creates a force moving the train forward.
I'm not so confident of the quality of this set though. This product begs the question - why the collaboration? and who actually made the product (and therefore determines the quality). It's not at all uncommon for a typically low quality Chinese company to "collaborate" with a high quality (usually Western) company. The Chinese company produces a low quality, cheap product, and pays the higher quality, well known company a fee to stamp their name on the product, thus attracting buyers who are after a high quality product.
Our second non-traditional commitment is in silver. Last year, we purchased million ounces. Marked to market, that position produced a pre-tax gain of $ million for us in 1997. In a way, this is a return to the past for me: Thirty years ago, I bought silver because I anticipated its demonetization by the . Government. Ever since, I have followed the metal's fundamentals but not owned it. In recent years, bullion inventories have fallen materially, and last summer Charlie and I concluded that a higher price would be needed to establish equilibrium between supply and demand. Inflation expectations, it should be noted, play no part in our calculation of silver's value.