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The physicochemical properties of diesel fuel and methyl ester of rapeseed oil are reviewed, graphical dependencies of density, kinematic and dynamic viscosity, surface tension of diesel fuel and rapeseed oil methyl ester are shown when the temperature in the diesel cylinder changes, chemical indicators of methyl esters of rapeseed oil on the characteristics of injection and spraying of fuel.

The possibility of fatigue crack propagation in the region of compression stresses is considered. After each semi-cycle of cyclic loading the stress-strain distribution near the tip of the crack is determined by the finite element method. It is shown that maximum of the tension stresses increases in the region of compression. The obtained results allow to present the possible ways of the above-mentioned fatigue crack propagation.

Using the example of operating gas fields in the Western Siberia, the issue of the correct choice of voltage class, considering all the periods of gas fields life cycle, appears. Wrong choice of the voltage class leads to braking development of a gas field. Gas field technological scheme during the each period of the life cycle is considered, the dynamics of the electrical load is estimated. The analysis of existing methods of choosing the voltage class is carried out and their flaws are revealed. Mathematical models of the optimal voltage class calculation and discounted costs calculation are developed using the theory of experiment planning. An algorithm of choosing the optimal voltage is developed and the distribution and supply networks of the external power supply system of the existing gas fields in Western Siberia are investigated. Progressive voltage class for power supply and distribution network is proposed. Conclusions are made.