This author presents the results of an analysis of the effect of directly measured quantities and their measurement (standard) deviations on the value of the total measurement uncertainty of roundness deviation. The methods described refer to the determination of roundness deviation based on the mean square element and basic mathematical transformations and relationships that provided a basis for the analysis. Its results are given in the form of diagrams followed by final conclusions

When hot exhaust gas is mixed with inlet air, the charge to a diesel engine is modi-fied in different ways: the charge temperature increases, the total charge mass is re-duced and the charge composition changes. This paper is concerned with the residual gas fraction that is usually determined by straight CO2 measurement in a sample of gas extracted from a cylinder during the compression stroke. A general zero-dimensional model for calculating the residual gas fraction in reciprocating internal combustion engines has been formulated. The model accounts for both the trapped gas in the cylin-der at top dead center and the back-flow of exhaust gas into the cylinder during the valve overlap period. The effect of EGR introduction has been discussed.