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Anti-friction properties of solid lubricating coatings dedicated for the decrease in friction and increase in seizure resistance in the piston skirt–cylinder liner couple of high-forced combustion engines have been compared. Various modifications of coatings based on a polymer binder with addition of high-purity molybdenum sulfide and graphite have been deposited onto the segment surface. The graphite-based coating (foreign manufacturer), which is now successfully employed for steel pistons in diesels of heavy vehicles, has been used as the reference specimen. The studies were carried out at the friction temperature of 110°С in the range of normal loads of 50–450 N at a constant reciprocating frequency of 20 Hz, which is comparable to operating conditions of tribocoupling in diesel engines. Analysis of the results has shown that deposition of all coatings significantly decreases the friction coefficient, which amounts to 0.12–0.14 in some coatings (containing simultaneously molybdenum disulfide and graphite), which corresponds to the condition of contact of friction surfaces in the presence of lubricating material and the absence of direct metal contact in the friction couple.

The solution to the problem of increasing the motor resource of an internal combustion engine (ICE) is directly related to the reduction of energy losses due to overcoming friction in the elements of systems, mechanisms, and complexly loaded tribo-couplers (TC). Among the mechanical friction losses, a special place isoccupied by the hydromechanical friction losses in the internal combustion engine. The reduction of energy losses to overcome friction is achieved by reducing mechanical losses by limiting the level of loading of the rubbing surfaces, by increasing the proportion of the liquid friction regime for the most critical in terms of reliability resource-determining complex loaded vehicles. For complexly loaded vehicles, the time and magnitude of the acting loads are characteristic, at which the position of the movable element in conjunction is characterized by high eccentricities. Such complexly loaded vehicles include the main and connecting rod bearings of the crankshaft, the “piston guide – cylinder liner” and “piston ring – cylinder liner” couplings, the thrust and thrust bearings of the ICE turbocharger, etc. One of the ways to reduce oil starvation isto texturize the contacting surfaces, which will increase the bearing capacity of a complex bearing due to the creation of many “micro wedges”. In particular, the texturing of the surface of the bearing shells of the crankshaft can be performed in the form of elliptical micro-holes, which allow you to save oil on the friction surface under any operating conditions of the diesel engine. The article provides an overview of the main types of microtexturing of friction surfaces of TC. A calculation model has been created and a calculation analysis program has been developed for the internal combustion engine “crankshaft neck-liner” TC. The calculations ofthe hydromechanical characteristics (HMC) of the vehicle for various types of microtexture were performed using the connecting rod bearing of the diesel engine CHN 13/15 as an example.

The solution to the problem of increasing the resource of an internal combustion engine (ICE) is directly related to the reduction of energy losses to overcome friction in the elements of systems, mechanisms and complexly loaded tribounits. A special place among the mechanical friction losses is occupied by the hydromechanical friction losses in the ICE tribounit. A complex loaded tribounit is characterized by loadings that are variable in time and magnitude, at which the position of the movable element in conjunction is characterized by high eccentricities. Such a complexly loaded tribounit includes the main and connecting rod bearings of the crankshaft, the interface “piston skirt-cylinder liner” and “piston ring-cylinder liner” and thrust bearings of the ICE, etc. The only way to reduce oil starvation is to texturize the contacting surfaces, which will increase the bearing capacity of a heavily loaded bearing by creating many “micro wedges”. In particular, the texturing of the surface of the liners of the crankshaft bearings can be performed in the form of elliptical pits, which allow the oil to be stored on the friction surface under any operating conditions of the diesel engine. The article provides an overview of the main types of micro-texturing of a friction surface tribounit. The calculation model was created and the program of calculation analysis “crankshaft journal bearing” was developed. The calculations of hydromechanical characteristics are performed for various types of micro-texturing by the example of a connecting rod bearing in a diesel engine for commercial vehicles.

Purpose. Analysis of distortions in the de-ramped linear frequency modulated continuous wave (LFM-CW) signal reflected from an extended target (ET), which model is presented by a set of point scatterers. Definition of parameters affecting distortions in the de-ramped signal spectrum, and development of ET radar profile restoration methods. Methodology. Numeric computations method based on the equation describing the de-ramped LFM-CW signal of an ET. The de-ramped signal properties analysis by means of numeric computation with varying values of properties of the probing signal and the ET. Findings. Parameters of the transmitted signal and the ET model that affect the distortions have been determined: starting frequency, frequency change rate, the ET relative height, the distance between the reflectors, the limits of phase noise values. The spectrum distortion index has been introduced. Value. ET radar profile restoration methods that can be used for signal processing have been developed.

The paper aims at designing the advanced simulation model that is able to generate samples similar to human respiration signals typically acquired by a Doppler or Continuous-wave step frequency short-range radar system. The model is based on the continuous non-linear transformation of the mixture of a sine wave with amplitude and frequency modulation and a colored Gaussian noise. Despite not being based on a detailed physiological description of the respiration process, the proposed model can produce samples of respiration signals resembling the signals acquired by a radar with high accuracy. In contrast to the widely-used monoharmonic model, the model does not exhibit strict periodicity that allows researchers to consider it to be an appropriate sample generator for thorough testing procedures performed over existing algorithms of respiration signal detection as well as newly-created ones.

The paper solved the problem of optimizing the piston skirt profile in the hot state according to the criteria of minimal frictional losses. The authors defined and improved the geometrical parameters of the piston design considering the optimum profile of the skirt; developed recommendations for improving the design of the piston. For six-cylinder V-shaped forced diesel engine, with a cylinder diameter of 150mm and a piston stroke of 160mm (further diesel) a piston design with improved tribological parameters was developed.

The article presents the results of a comprehensive approach to the research and development of technical solutions for the main tribosystems of six-cylinder V-shaped forced diesel engine, with a cylinder diameter of 150mm and a piston stroke of 160mm (further diesel). Technical solutions for diesel are evaluated by solving the problem of dynamics and lubrication of friction units on the basis of a single algorithm for hydrodynamic tribosystems with the reciprocation and rotation movement of the elements with a non-Newtonian fluid

The reliability of many machines and mechanisms is mainly determined by the reliability of friction pairs (in particular, journal bearings). So the journal bearings in the piston engine are mostly operated in the hydrodynamic lubrication regime and, at high loading levels, in the transient and mixed lubrication regimes. The latter is important for the determination of the service life of the tribosystem as a whole. For this aim, in this paper, we describe, develop, and apply an approach proposed earlier to build models of the interaction of rough surfaces for one of the tasks of simulation of tribological systems of the piston engine. Previously suggested models can estimate the area of contact, the friction force, coefficient of friction, wear, etc. However, this approach ignores the surfaces change and, consequently, contact and friction characteristics over the time. We described the general approach to build a model of interaction between rough surfaces, leading to the analysis of the Markov process. This method we applied for friction process and for the fatigue failure mode in which the surface element is destroyed after repeated contacts, the order of many millions. Given the initial data and the method of calculating the trajectory of movable elements on the lubricating layer taking into account rheological characteristics of lubricants, we determined the tribological parameters defining the resource of crankshaft bearings and the “piston–cylinder liner” tribosystem of the high forced piston engine.

The technique for determining the movable (holes in the crank bearing) and fixed (grooves on the surface of the pad) lubricant sources for lubricant supply to the heavy-loaded friction type bearing is considered. To determine the field of hydrodynamic pressures in the bearing lubrication layer, two modifications are taken into consideration: the modification of the algorithm for integrating the modified Elrod equation for the degree of the gap feeling. Further studies showed that developed modifications were proved to be quite effective in calculating the characteristics of the lubricating layer for both statically and dynamically loaded bearings. However, for the first modification, numerical oscillations of the unknown function at the boundary of the reduction of the lubricating layer were noticed. The second modification, for which the finite difference algorithm was used, is characterized by the simplicity of implementation and the stability of the iterative procedure. The example of connecting rod bearings of the crankshaft of the combustion engine is used to consider the influence of the location of the lubrication sources on the hydromechanical characteristics of complex loaded friction type bearings. Original schemes of location of partial and complete oil distribution grooves for lubricant supply for connecting rod bearings are proposed. It is shown that an additional method for improving hydromechanical characteristics is the selection of engine oil with improved viscosity–temperature characteristics.

The present paper discusses the spatial and stratigraphic analysis of an assemblage of archeological remains from the newly found point B (lettered in Cyrillic) of the Eastern Gravettian site Khotylevo 2. The new find was discovered by the Khotylevo Archaeological Expedition in 2005. The cultural layer of the site relates to a level of initial soil formation at the base of the Desna loess horizon. The stratigraphic position of the cultural layer at point B is typical of the entire Khotylevo 2 site and does not differ substantially from those at points А and Б. Currently, two closely related assemblages of archeological remains have been discovered at point B over an area of 45 m 2 . The first assemblage is noted for the presence of rounded shallow pits and embedded mammoth bones surrounding concentrations of bone coal; it also contains split animal bones, and flint splinters. Similar assemblages were discovered by F.M. Zavernyaev during the excavations at Khotylevo 2 in the 1970s. The second assemblage is marked by large clusters of intentionally arranged bones of woolly mammoth (Mammuthus primigenius). There is a certain pattern traceable in the bone arrangement, similar to those observed in mammoth bone structures of the Anosovka-Mesin dwellings. Microstratigraphic correlation of the two assemblages considered together with the radiocarbon dates strongly suggests them to be of different ages. The most abundant bone remains within the studied area belong to woolly mammoth. The list of mammal species identified from this site shows no significant difference from species lists known from other sites of the Russian Plain dated to the same chronological interval. The scarcity of bones belonging to other herbivorous mammals may be due to the fact that no butchering was performed at this part of the site. The abundance of mammoth bones does not directly indicate simultaneous overkill of those animals; it is quite possible, however, that individual animals were killed periodically.

The problem of calculating the hydromechanical characteristics of complex-loaded sliding bearings is formulated in which the cross section of the bearings is shaped to limit the lubricating layer and the shape is different from the ideal (round cylindrical) one. The results of calculation of the hydromechanical characteristics of the crankshaft connecting-rod bearing of a diesel engine are analyzed where the pivot journal and bush are oval.

Crankshaft rod bearings of a combustion engine are used as an example to show the technique and results of optimization of the design parameters of friction bearing under a complex load. The field of hydrodynamic pressures in a lubricating layer, which separates the crank pin and the bearing lining, is determined by integrating the equation for filling of the gap. This approach ensures observance of the condition of lubricant continuity at the boundaries of discontinuity and restoration of the lubricating layer. The lubricant viscosity, which is assumed to be an effective function of the temperature of the lubricating layer, is adjusted at each step of the calculation of the crank pin’s motion trajectory.

A new multi-alternative k-stage procedure of radar detection is proposed and the method of its optimization developed. Analysis of the procedure for the case k=4 shows that it has a gain of 1.5-2 times in average sample numbers versus the multichannel modified Wald's procedure. The efficiency of the procedure for k=4 in comparison with the multichannel single-stage procedure with a fixed number of samples is discussed. The research shows that application of the developed multi-alternative k-stage procedure can considerably enhance radar efficiency in the detection mode. The use of the universal technique of the k-stage procedures optimization provides ample opportunities for the design of efficient sequential detectors for modern radars.

The motion of the solid-phase particles under gravity is considered for the films formed by contact melting, with additional effects from the forces produced by motion of the crystallization front and those due to differences in the partial diffusion coefficients. Recommendations are made on selecting the contact-melting and crystallization conditions to reduce the effects of these forces. It is possible to reinforce the contact films on account of the displacement of the solidphase particles produced by the gravitational forces and the forces due to differences in the partial diffusion coefficients.