The talk will be suitable for a general audience.
Students are strongly encouraged to participate.
We present new models, set as systems of delay-differential equations with
hysteresis, for the dynamics of automotive thermostats. The novelty is
in the combination of delays and hysteresis. The main interest in these
models lies in the intrinsic oscillations that they predict, which real
thermostats are known to exhibit. Such oscillations are highly udesirable
in practice, since they cause oscillations in the engine operating temperature,
which in turn impacts on emissions, fuel economy and engine wear. Sufficient
conditions for oscillations relate the delay to the slope of the hysteresis
curve and the cooling rate. A numerical algorithm and numerical simulations
will be presented too. The models predict the appearance of oscillations
in certain parameter ranges. These models may be used in the engine cooling
system design stages to minimize engine temperature oscillations. Many open
quastions remain, among them the possible classification of the oscillations.
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