A method for regenerating a particulate filter may comprise calculating a first estimated soot load of a particulate filter based on a pressure drop of an exhaust gas flowing through the particulate filter, and calculating a second estimated soot load of the particulate filter based on a mass balance of soot in the particulate filter. The deployment shelter 10 has a shelter main body 20 in which a floor panel 28 is coupled to a roof panel 29 via four poles. A reference capacitor and a calibration capacitor are also provided and have nominally the same capacitance. The heaters in the group are electrically coupled below the surface of the formation. During surgery and recovery at a surgical center or hospital, the vacuum source attached to the delivery system may be an industrial type vacuum source.