efficiencysince

Efficiencysince is a conceptual metric that describes how the current efficiency of a system compares to its efficiency at a defined baseline event, as a function of the time elapsed since that event. The baseline is often the moment of commissioning, the most recent maintenance, calibration, or another reference point. The term is used in reliability engineering and performance monitoring to separate effects of aging, wear, or adjustment from other variables that influence output.

Mathematical framing commonly treats efficiencysince as the ratio η_since(t) = η(t) / η0, where η0 is the baseline efficiency and t is the time since that baseline. In systems subject to degradation, the degradation factor D(t) may be modeled as a decreasing function, for example D(t) = e^{-λt}, yielding η_since(t) ≈ e^{-λt}. In contexts where performance improves through learning or optimization, η_since(t) can rise toward a plateau. The metric is flexible and can be adapted to different definitions of efficiency, such as energy efficiency, output per input, or quality-adjusted throughput.

Measurement and use involve collecting performance data, normalizing by the baseline, and often applying smoothing or moving-average techniques to reduce noise. Efficiencysince is applied in manufacturing, energy systems, data centers, and logistics to monitor aging, guide maintenance scheduling, compare units, and track improvement efforts. Limitations include sensitivity to the chosen baseline, external disturbances, and the fact that it captures a single dimension of performance rather than overall effectiveness. See also efficiency, degradation, and maintenance optimization.