Introduction. Simultaneous operation of numerous sources of radio emission form complex signal environment. Different devices with the common name "wideband analyzers" (WBA) are widely used to analyze and to control such environment. There is currently a need for developing the quantitative characteristics of a complex signal environment, which will make it possible to predict the stability of the WBA operation. Aim. The development of the indicator of the signal environment complexity, which will make possible the quantitative assessment of such environment. Materials and methods. To provide the desired indicator, simulation and mathematical tools for random events description are used. All calculations are performed using MatLab. Results. The principles of disturbances in the WBA receiver and algorithmic errors in the processing of overlapped signals are described. To quantify the "complexity" of the signal environment it is proposed to use the probability that pulses from several sources overlap in time. This allows one to compare signal environments with each other. The new analytical expression for estimating the pulse overlap probability is proposed. Functions of the pulse overlap probability from the complex signal environment parameters were obtained. Conclusion. According to the comparative analysis of the calculations using proposed analytical expression and simulation, the new expression allows one to achieve the calculation speed up to 6 orders of magnitude higher with an error below 7% compared to the simulation. The high performance of the calculations using the proposed expression allows one to simulate the complex signal environment in dynamics more efficiently.

High levels of dynamic loads in a modem diesel engine take place at low frequencies and are connected with the forced vibration of the engine under the action of excitation gas and inertia forces. The lower range of these frequencies are equivalent to the speed of the engine (two stroke) and half engine speed (four stroke). They lead to high stress levels and deformations and often cause internal damage or component failure as well as increasing vibration transmitted to the foundation. One of the most important factors in improving the reliability and durability of engine components and reducing the level of vibration is providing sufficient rigidity for the engine housing. Careful choice of the main dimensions and design parameters will greatly influence engine performance. An engineering approach to the Finite Element analysis of low frequency forced vibration is proposed for the elastic system including crankshaft, engine housing, elastic mounting and foundation. This approach is applied to the analysis of medium speed marine diesel engines with particular attention being paid to the analysis of the rigidity of the engine housing. A solution procedure is proposed to define the loads transmitted from the crankshaft to the main bearings. The procedure takes into account the reciprocal influence of elastic and inertial characteristics of the crankshaft and the engine housing mounting on the elastic foundation, alteration of load amplitudes according to the angular position of the crankshaft, and hydrodynamic behaviour of the lubricating oil film in the contact zone.

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