Abstract: A vehicle detector with improved reference tracking routines in both the Call direction and the No Call direction. Call direction tracking includes rate sensitive tracking in which the reference is only changed in response to small fluctuations in loop frequency due to drift, and one or more fixed decrementing tracking intervals during which the reference is decremented at a fixed rate for a maximum predetermined period of time. Call direction tracking also includes infinite tracking during which the reference is decremented to an end value representative of loop inductance prior to the generation of a call signal. No Call tracking permits reference updating only after the loop frequency has stabilized for a minimum period of time, a minimum number of loop frequency samples or both.

Abstract: A pollution-free thermodynamic engine system and method for converting thermal potential energy to useful mechanical energy employing an isothermal or quasi-isothermal primary working fluid thermodynamic expansion cycle. A relatively cold primary working fluid is conducted from a low temperature storage tank, through a plurality of engine stages each comprising a heat exchanger and an expansion engine operated on an isothermal of quasi-isothermal expansion cycle, and finally exhausted. A relatively warm secondary fluid is circulated through the engine stages to provide a heat input thereto. The engine stages are connected to the primary working fluid path in parallel to operate on a first isothermal expansion cycle; the engine stages are cascaded to operate on a second serial isothermal expansion cycle.

Abstract: A fluid eductor for injecting a secondary fluid e.g. air, oxygen, ozone or other reactant fluids into a primary fluid, e.g. oxygen, waste water, depleted water, sewage fluids or other reactant fluids flowing in a conduit. A spool housing having a generally cylindrical header assembly interior thereof is mounted in the conduit in the flow path of the primary fluid. In a first embodiment, the header assembly comprises a hollow tank, an inlet pipe coupled to an external supply of secondary fluid, a plurality of flow through pipes extending through the header tank along the secondary fluid flow path and terminating downstream of the tank, and a corresponding plurality of conical platelet assemblies each arranged concentrically of the associated flow through pipe. Each conical platelet assembly provides a plurality of flow passages in communication with the interior of the tank and the associated flow through pipe to permit secondary fluid to be injected into the primary fluid flowing through the pipe.