Introduction. An efficient technique of tensor field scalarization  is  successfully  used  while  investigating  tensor  elastic fields of displacements, stresses and deformations in the layered structures of different materials, including transversally isotropic composites. These fields can be expressed through the scalar potentials corresponding to the quasi-longitudinal, quasi-transverse, and transverse-only waves. Such scalarization is possible if the objects under consideration are tensors relating to  the subgroup  of general coordinate conversions, when the local affine basis has one invariant vector that coincides with the material symmetry axis of the material. At this, the known papers consider structures where this vector coincides with the normal to the boundary between layers. However, other cases of the mutual arrangement of the material symmetry axis of the  material  and  the boundaries between layers are of interest on the practical side.

Materials and Methods. The work objective is further development of the scalarization method application in the boundary value problems of the dynamic  elasticity theory for the cases of an arbitrary arrangement of the material symmetry axis relative to the boundary between layers. The present research and methodological apparatus are developed through the general technique of scalarization of the dynamic elastic fields of displacements, stresses and strains in the transversally isotropic media.

Research Results. New design ratios for the determination of the displacement fields, stresses and deformations in the transversally isotropic media are obtained for the cases of an arbitrary arrangement of the material symmetry axes of the layer materials with respect to the boundaries between layers. Discussion and Conclusions. The present research and methodological apparatus are successfully used in determining the stress-strain  state  in  the  layered  structures  of  transversally isotropic materials, and in analyzing the diagnosis results of the state of the plane-layered and layered cylindrical structures under operation.

Introduction.  The investigation of the contact problems  for cylindrical bodies is urgent due to the engineering contact strength analysis on shafts, cores and pipe-lines. In the present paper, a new contact problem of elastostatics on the interaction between a rigid band and an infinite two-layered cylinder, which consists of an internal continuous cylinder and an outer hollow one, with a frictionless contact between the cylinders, is studied. The outer cylindrical band of finite length is press fitted. By using a Fourier integral transformation, the problem is reduced to an integral equation with respect to the unknown contact pressure.

Materials and Methods. Different combinations of linearly elastic materials of the composite cylinder are considered. Asymptotics of the symbol function of the integral equation kernel at zero and infinity is analyzed. This plays an important role for the application of the analytical solution methods. A key dimensionless geometric parameter is introduced, and a singular asymptotic technique is employed to solve the integral equation.

Research Results. On the basis of the symbol function properties, a special easily factorable approximation being applicable in a wide variation range of the problem parameters is suggested. The Monte-Carlo method is used to determine the approximation parameters. The asymptotic formulas are derived both for the contact pressure, and for its integral characteristic. Calculations are made for different materials and for various relative thickness of the cylindrical layer  including thin-walled layers.

Discussion and Conclusions. The asymptotic solutions are effective  for  relatively  wide  bands  when  the  contact  zone length is bigger than the diameter of the composite cylinder. It is significant that the method is applicable also for those cases when  the  outer  cylindrical  layer  is  treated  as  a  cylindrical shell. The asymptotic solutions can be recommended to engineers for the contact strength analysis of the elastic barrels with a flexible coating of another material.

Introduction. Reliability-Based Design Optimization (RBDO) model reduces the structural weight in uncritical regions, does not only provide an improved design but also a higher level of confidence in the design.

Materials and Methods. The classical RBDO approach can be carried out in two separate spaces: the physical space and the normalized space. Since very many repeated researches are needed in the above two spaces, the computational time for such an optimization is a big problem. An efficient method called Optimum Safety Factor (OSF) method is developed and successfully put to use in several engineering applications. Research Results. A numerical application on a large scale problem under  fatigue  loading  shows  the  efficiency of the developed RBDO method relative to the Deterministic Design Optimization (DDO). The efficiency of the OSF method is also extended to multiple failure modes to control several out-put parameters, such as structural volume and damage criterion.

Discussion and Conclusions. The simplified implementation framework of the OSF strategy consists of a single optimization problem to evaluate the design point, and a direct evaluation of the optimum solution considering OSF formulations. It provides designers with efficient solutions that should be economic, satisfying a required reliability level with a reduced computing time.

Introduction. The effect of the organic component nature in the systematic series of monocarboxylic acids on the tribological characteristics of the brass-steel friction pair in aqueous solutions is described. Dependence of the mechanical-and-physical properties of the antifriction films formed during friction on the nature of the lubricating composition is investigated. The work objectives are to study the applicability of carboxylic acids as an antifriction lubricant component; to assess their effect on the mechanical properties of the servovite film formed under the brass – steel friction.

Materials and Methods. Tribological studies of the brass-steel friction pair on the AE-5 end-type friction machine are carried out. Roughness parameters of the servovite  film were determined through the optical profilometry. The microgeometry and the object structure at the nanoscale were considered using atomic force microscopy. The mechanical characteristics of the antifriction film were investigated using the instrument nanoindentation.

Research Results. Tribological characteristics of the brass-steel tribocoupling and mechanical-and-physical properties of the servovite film formed during friction in the “brass – aqueous solution of carboxylic acid – steel” system were studied. It is established that the friction factor reduces when increasing the hydrocarbon radical length. The dimensional effects are found in the mechanical and tribological properties of the servovite film formed on the surface of the friction interaction in the carboxylic acids.

Discussion and Conclusions. The study results show that the friction interaction on the wearing surface in the aqueous solutions of carboxylic acids forms a nanostructured servovite film which drops the friction factor. Its mechanical, physical and tribological parameters depend on the composition of the model lubricating medium. It is determined that the local mechanical-and-physical properties depend on the method of producing the servovite layer, the load and the size of the deformation zone. The results obtained can be used in the development of lubricants.

Introduction.  Power  parameters  of  the  “rolling  −  equalchannel angular pressing” (ECA) combined process are studied. The work objective is to determine forces of rolling and pressing in the deformation by the combined method.

Materials and Methods. The die strength calculation and the experiment on deformation of AISI 6063 aluminum samples were carried out. During the experiment, the force values were recorded using a strain-gauge station.

Research Results. The strength analysis results show that this die design is suitable for creating an experimental stand of the “rolling − ECA-pressing” combined process, since the calculated  safety  margin  is  sufficient  to  implement  the  pressing under extreme conditions. The rolling forces at all stages of the  deformation  exceed  the  corresponding  pressing  forces, which is a necessary condition for the combined process. Discussion and Conclusions. The obtained results can be used in the design of experimental stands that implement the investigated combined  process. Herewith, the given  strain-gauge method for studying strength characteristics is suitable for the case of calibrated rolls.

Introduction. Generation of composite materials with addition of sawdust is considered. The wood component of the composites is treated with water to enhance the surface roughness. This increases the contact area resulting in intensifying the sawdust – polymer fibers interaction. The work objective is to study the possibility of strengthening composites obtained from sawdust.

Materials and Methods. Samples are made of composite materials based on the unsaturated polyester resins, reinforced with wood chips. Water treatment was carried out at room temperature for 2, 4, 6 and 8 days. Then the samples were tested for bending and compression.

Research Results. As a result of testing the samples, changes in their  mechanical  properties  were  recorded.  It  is  determined how the bending and compression resistance depends on the water treatment time. Graphs that reflect these dependences are constructed.

Discussion and Conclusions. After water treatment, the composites reinforced with sawdust show a higher resistance to bending. This is due to the increased roughness of the sawdust surface and, as a consequence, to the extension of the surface area adhesion with the composite base. Besides, the water treatment enhances the specimen resistance under compression. The samples created on the basis of large sawdust come into particular prominence. This is due to the formation of holes on the sawdust surface which also enhances the adhesion between them and the composite polymer base.

Introduction. The electroacoustic application of wear-resistance coatings is studied. The work objective is to obtain a mathematical model of the ultrasonic effect on the formation and development of an electric spark occurring in the process of the electroacoustic sputtering.

Materials and Methods. The effect of ultrasonic vibrations on the processes occurring during the formation and development of a spark discharge is analyzed; the equations of continuity, energy motion and transfer, with the ultrasonic field contribution are considered. Factors affecting the thermal conductivity and electrical conductivity of strongly ionized gas are studied. Research Results. When obtaining the model, it was assumed that the heat removal from the channel is carried out by a “clear emitter”. Then, for the channel region, a self-similar solution is made: pressure, temperature and density are constant over the cross-section, and velocity is proportional to the radius. A mathematical model that describes the processes occurring in the spark channel with the ultrasonic field energy effect is obtained.

Discussion and Conclusions. On the basis of the developed model, it is specified that under the ultrasonic radiation effect, the radius and temperature of the spark channel increase, and conditions of the double ionization under high ultrasonic energy are created.

Introduction. The sources of damage and wear of the main shaft of the  drier  toaster  are  analyzed.  The  repair  know-how  and welding operations execution limitations which must be considered when developing the technique providing the restoration of the structure performance  features are studied. The work objective is to develop a technique of repair without dismantling  for  the  main  toaster  shaft.  To  solve  the  task,  a design   repair   structure   was   installed,   and   postwelding operations  that  meet  the  engineering  and  regulatory requirements for this structure were performed.

Materials   and   Methods.   In   “Kompas   3D”   software,   the following models were developed: integral shaft (project shaft design); damaged shaft as a result of long-term operation (more than  15  years);  and  damaged  shaft  with  a  welded  repair structure. Numerical simulation of the stress-strain state (SSS) was carried out.

Research Results. Software for the computational modeling of the repair structure SSS is developed. The repair shaft structure in which the maximum stresses do not exceed the shaft stresses in the project design is obtained using the model. To eliminate the aggressive medium effect on the corrosion fatigue strength of the shaft, an insulating method is used. A technique for mounting  the  repair  structure  to  the  shaft  allowing  for  the outrun limitation 0.12 mm is developed.

Discussion and Conclusions. Torsion shafts damaged deeply by wear and corrosion are considered. To restore their structural integrity, it is worthwhile using the following complex of techniques:

— constructive (consists in the installation of optional parts that compensate for insufficient strength, and provides a reduction in stress concentration in the most loaded zones);

— processing (reduces residual welding stresses due to the reasonable sequence of deformation that contributes to generating favorable residual compressive stresses);

—  isolation  (is  based  on  the  application  of  anticorrosion coatings).

The economic expediency of the developed repair technique is obvious. The repairing of the shaft without dismantling costs 180,000 rubles, while a new shaft costs 3.8 million rubles.

Introduction. Issues on the functional unification of the adaptive hydraulic  drive  module  are  studied.  For  the  first  time,  self-adapting   mechanisms   are   considered   taking   into   account adaptive intercommunication of the load control and agreement of motions on the working body of the mobile machines. The work objective is to create and analyze the technique of the functional unification of the adaptive hydraulic drive module. In the furtherance of this goal, a number of tasks are solved. The selection of technical equipment – unified adaptive hydraulic drive  modules  of  the  mobile  machines  –  is  validated.  The methodology   and    indicators   of    the    module    functional unification are described. Intercommunications are considered: direct  positive  and  back  negative  ones.  Their  effect  on  the functional unification property of the adaptive module is shown.

Materials and Methods. For the synthesis and analysis of the functional  unification  indicators  of  the  adaptive  module,  a similarity method of the technical systems operation is adopted.

Research     Results.     Techniques     for     structural-functional unification   of   the   self-adapting   modules   are   developed. Optional  versions  of  the  unified  modules  modification  and proper combinations of hydraulic motors, regulating equipment, and  mathematical  models  of  adaptive  communications  are presented. Criteria  and  indicators  of similarity are  proposed. The functional unification of the adaptive intercommunications of the module and different types of the hydraulic motors and fluid throttling elements in the hydraulic system are analyzed. Recommendations for implementing the functional unification under typing and operation (adjustment) of the adaptive module are formulated.

Discussion and Conclusions. The methodology is recommended for the functional unification of the hydraulic self-adapting module. It can be used for the development of unit sizes and under its operation as an independent drive or a hydraulic drive subsystem of a multifunctional or combined machine.

Introduction. The development of a mathematical model for the groundwater level of a deposit of cement raw materials located in the Zadonian-Yelets aquifer, which is the principal domestic water supply source for the city of Lipetsk, is considered. Therefore, it is necessary to provide ongoing monitoring and to have the possibility to  predict the water level under the field development. The work objectives are the identification  and  study of a  dynamic  neighborhood  model with variable hierarchical neighborhoods of the groundwater level that enables to adequately predict value of the water level in the examined wells.

Materials and Methods. The definition of a dynamic neighborhood model with variable hierarchical neighborhoods is given, differing by time-varying double-level neighborhood communications between the first- and second-level nodes. At each next discrete instant of time, the neighborhood model nodes change their state under the influence of the online parameters and node states included in their neighborhood. As a subcase, we consider a model with line state recalculation functions. Parametric identification of the dynamic neighborhood model consists in finding the system parameters for each second-level node, and is based on the ordinary least squares.

Research Results. A linear dynamic neighborhood model with variable hierarchical neighborhoods for predicting the groundwater level in a cement raw material deposit located in the Zadonian-Yelets aquifer is developed. The software using C++ is developed for the parametric identification and simulation of the functioning of the dynamic neighborhood model under consideration. It enables to determine parameters of the node state recalculation functions for a given structure, and  also  to  predict  the  model  behavior  in  the  operation process. A hierarchical structure is given, and a parametric identification of the linear dynamic neighborhood model of the groundwater level is carried out. After the parametric identification on the teaching data selection, the mathematical model is checked on the test sample.

Discussion and Conclusions. The obtained average ratio errors of the identification and forecast suggest the developed model validity  and  enable  to  recommend  it  for  predicting  the underground water level of a cement raw materials deposit.

Introduction. Production processes quality depends largely on the management infrastructure, in particular, on the information system (IS) effectiveness. Company management pays increasingly greater attention to the safety protection of this sphere. Financial, material and other resources are regularly channeled to its support. In the presented paper, some issues on the development of a safety enterprise information system are considered.

Materials and Methods. Protection of the enterprise IS considers some specific aspects of the object, and immediate threats to IT security. Within the framework of this study, it is accepted that IS are a complex of data resources. A special analysis is resulted in determining categories of threats to the enterprise information security: hacking; leakage; distortion; loss; blocking; abuse. The connection of these threats, IS components and elements of the protection system is identified.  The requirements of normative legal acts of the Russian Federation and international standards regulating this sphere are considered. It is shown how the analysis results enable to validate the selection of the elements of the IS protection system.

Research Results. A comparative analysis of the regulatory literature pertinent to this issue highlights the following. Different documents offer a different set of elements (subsystems) of the enterprise IS protection system. To develop an IS protection program, you should be guided by the FSTEC Order No. 239 and 800-82 Revision 2 Guide to ICS Security.

Discussion and Conclusions. The presented research results are the basis for the formation of the software package of intellectual support for decision-making under designing an enterprise information security system. In particular, it is possible to develop flexible systems that allow expanding the composition  of the components (subsystems).

Introduction. Polynomials in several variables over Galois fields provide the basis for the Reed-Muller coding theory, and are also used  in a number of cryptographic problems. The properties of such polynomials specified over the derived Galois fields of fuzzy cardinality are studied. For the results obtained,  two  real-world  applications  are  proposed: partitioning scheme and Reed-Muller code decoder.

Materials and Methods. Using linear algebra, theory of Galois fields, and general theory of polynomials in several variables, we have obtained results related to the differentiation and integration  of polynomials  in  several  variables  over  Galois fields of fuzzy cardinality. An analog of the differentiation operator is constructed and studied for vectors.

Research Results. On the basis of the obtained results on the differentiation and integration of polynomials, a new decoder for Reed-Muller codes of the second order is given, and a scheme for organizing the partitioned transfer of confidential data is proposed. This is a communication system in which the source data on the sender is divided into several parts and, independently of one  another,  transmitted  through  different communication channels, and then, on the receiver, the initial data is restored of the parts retrieved. The proposed scheme feature is that it enables to protect data, both from the nonlegitimate access, and from unintentional errors; herewith, one  and  the  same  mathematical  apparatus  is  used  in  both cases. The developed decoder for the second-order Reed-Muller codes prescribed over the derived odd Galois field may have a constraint to the recoverable error level; however, its use is advisable for a number of the communication channels.

Discussion    and    Conclusions.    The    proposed    practical applications   of   the   results   obtained   are   useful   for   the organization of reliable communication systems. In future, it is planned  to  study  the  restoration  process  of  the  original polynomial by its derivatives, in case of their partial distortion, and the development of appropriate applications.