In order to improve efficiency for sub-carrier allocation in a TDM multi-carrier system, the invention provides a novel frame structure and corresponding method and apparatus. The first charge source is chargeable to a first voltage potential and the second charge source is chargeable to a second voltage potential. A steam pipe has a first end and a second end, with the first end communicating with the heating room. Each road segment may be part of a calculated route and the simulation may include views for all the road segments contained in the calculated route.