Abstract: A method for determining sensor parameters of an actively-driven sensor system may include obtaining as few as three samples of a measured physical quantity versus frequency for the actively-driven sensor system, performing a refinement operation to provide a refined version of the sensor parameters based on the as few as three samples and based on a linear model of an asymmetry between slopes of the measured physical quantity versus frequency between pairs of the as few as three samples, iteratively repeating the refinement operation until the difference between successive refined versions of the sensor parameters is below a defined threshold, and outputting the refined sensor parameters as updated sensor parameters for the actively-driven sensor system.

Abstract: A boiler including a water jacket surrounding upper and lower combustion chambers for receiving heat for heating water or other fluid therein, which chambers are defined by a refractory structure that extends entirely across the inner casing. A vertical passage through the refractory structure provides for flow of combustion gases from the upper to lower combustion chamber. Oxygen is provided through a first forced air inlet to the upper combustion chamber for burning of wood or biomass, and is provided through a forced air passage in the refractory structure and opening into the vertical passage thereby providing at least one second forced air inlet for burning of the combustion gases and particulates passing therethrough. The refractory structure sealingly engages the inner casing in a manner to seal the upper combustion chamber from the lower combustion chamber so that the upper combustion chamber can be made substantially air tight.

Abstract: A solid fuel burning heater has an inner combustion chamber housing enclosed within an outer housing with a fuel feed door in the inner combustion chamber housing being aligned with an outer housing door; an air inlet in the bottom of the combustion chamber housing has a thermostatically controlled air inflow closure valving member connected to a wire bail having an upper end encircling a cam rod connected to the outer housing door. Opening movement of the outer housing door moves the cam rod so that the air inflow closure valving member is opened to provide combustion air into the combustion chamber and prevent blowback upon the subsequent opening of the fuel feed door.