A method is provided for an engine. During this method, a saturation current of a gas flow is measured. The gas flow includes combustion products generated by the engine. The saturation current is monitored to determine presence of debris entrained within the gas flow.

A method is provided for an engine. During this method, a saturation current of a gas flow is measured. The gas flow includes combustion products generated by the engine. The saturation current is monitored to determine presence of debris entrained within the gas flow.

A system and method for adjusting a position of an oil-water interface layer. A vessel, such as a free water knockout or a treater used in the processing of heavy oil, contains a fluid comprising the interface layer. A nuclear densitometer is positioned to obtain density measurements of the fluid at various heights along the vessel. Based at least in part on these density readings, a valve controlling flow out of a water discharge port on the vessel may be actuated, with the flow of water through the water discharge port being inversely proportional to the height of the interface layer.

The present invention relates to the use of a substrate for enhancing the fluorescence of a fluorescent molecule, wherein the substrate comprises a solid polymer carrier having a plurality of recesses separated from each other and wherein the solid carrier is coated at least in part by a metal.