commutative properties of four-dimensional generalized symmetric pseudo-riemannian manifolds were considered. specially, in this paper, we studied skew-tsankov and jacobi-tsankov conditions in 4-dimensional pseudo-riemannian generalized symmetric manifolds.

The task of improving the economic and ecological parameters of the internal combustion engines remains topical within the frameworks of the modern engine-building technology. Since a combustion engine is a complex system combining such units as an intake manifold, combustion chamber, exhaust manifold, one of directions of the engine development is adjustment of the joint operation of its units...

UTEP has developed a dedicated E85 vehicle with superior emissions and cold starting characteristics when compared to the original gasoline vehicle, and with no apparent differences in performance and driveability. All fuel system components that were not E85 compatible have been replaced or modified. Cold start characteristics are improved by incorporating a high frequency multiple spark ignit...

Many model based solutions to diagnosis problems in SIengines have been discussed in literature. However most presented methods are useful only for a specific class of faults. Here a systematic and more general method is presented. With this method, which is based on a structure of hypothesis tests, it is possible to diagnose a large variety of different types of faults. The method is applied t...