disk fans used in all previous installations. Nothing further was ever constructed. Aeromovel The nineteenth century attempts to make a practical atmospheric system (described above) were defeated by technological shortcomings. In the present day, modern materials have enabled a practical system to be implemented. Towards the end of the twentieth century the Aeromovel Corporation of Brazil developed an automated people mover that is atmospherically powered. Lightweight trains ride on rails mounted on an elevated hollow concrete box girder that forms the air duct. Each car is attached to a square plate—the piston—within the duct, connected by a mast running through a longitudinal slot that is sealed with rubber flaps. Stationary electric air pumps are located along the line to either blow air into the duct to create positive pressure or to exhaust air from the duct to create a partial vacuum. The pressure differential acting on the piston plate causes the vehicle to move. Electric power for lighting and braking is supplied to the train by a low voltage (50 V) current through the track the vehicles run on; this is used to charge onboard batteries. The trains have conventional brakes for accurate stopping at stations; these brakes are automatically applied if there is no pressure differential acting on the plate. Fully loaded vehicles have a ratio of payload to dead-weight of about 1:1, which is up to three times better than conventional alternatives. The vehicles are driverless with motion determined by lineside controls. Aeromovel was designed in the late 1970s by Brazilian . The system was first implemented in 1989 at Taman Mini Indonesia Indah, Jakarta, Indonesia. It was constructed to serve a theme park; it is a loop with six stations and three trains. In the late 2010s the system was closed for a period and re-opened in 2019 with only one train operational, which had been converted to diesel power. A second installation, the Metro-Airport Connection opened in August 2013. The line connects the Estação Aeroporto (Airport Station) on the Porto Alegre Metro and Terminal 1 of Salgado Filho International Airport. The single line is long with a travel time of 90 seconds. The first 150-passenger vehicle was delivered in April 2013 with a 300-passenger second vehicle delivered later. In December 2018 a pneumatic railway research and development centre was unveiled in China, developed by collaboration between Aeromovel and the China Railway Engineering Group (CREG). The firms