A mobility management method includes: receiving a first location update request sent by a Mobile Agent ; and determining, according to the first location update request and a binding relation between an MA context and a UE context, that a User Equipment moves together with the MA. One or more accounts is created, including a first and a second account, wherein the first account is assigned to a first user and the second account is assigned to a first computer. The control terminals of the controllable paths are coupled to a source terminal of the field-effect transistor. A lever actuated latching mechanism may be used to lock the removable access panel and the battery within the portable computer. A method for manufacturing an aqueous fuel emulsion is also disclosed.