The invention relates to distributed wireless ad hoc networks having interfering transmission channels, in which direct links between adjacent transmit nodes and receive nodes in a connection pair are established and optimized. Preferably, exhaust gas from the internal-combustion engine flows at least essentially around the fuel cell. This known force is used to calibrate, and ensure proper operation of a seal force testing device. The one or more parameters may include using low ion energy ions for removing material from the sample to expose progressively deeper layers of the sample, using an ion beam having a low ion angle to perform such removal of sample material, andor using an analyzer positioned at a high analyzer angle for receiving photoelectrons escaping from the sample as a result of x-rays irradiating the sample. The oil pressure pump 44 is a two-way discharge fixed capacity type, and rotated by a servomotor 46.