A method of estimating composition of fuel in the fuel tank of a vehicle. A refuel event is detected. Fuel consumption is monitored during a plurality of stages after the refuel event. A plurality of fuel trim shift values are determined relative to the stages. The fuel trim shift values are used to estimate a fuel composition change. This method eliminates a need for a hardware fuel composition sensor and also provides dynamic filtering of fuel trim values.

 
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> Method and apparatus for measuring dimension using electron microscope

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