Introduction. When developing ocular prostheses, a number of problems arise, one of which is the construction of the connection between the hard optical part and the soft corneal tissue. Their Young's modules can differ by three orders of magnitude. In this case, the problem arises of creating an intermediate layer, possibly with gradient properties, whose purpose is to exclude injury to soft biological tissues. Two types of keratoprostheses are considered: the first type with a support plate and the second type with an intermediate functionally gradient layer. The stress-strain state of the prosthesis is calculated for the first type. For the second type, analytical and finite element modeling of the interaction of a cylindrical optical prosthesis, an intermediate inhomogeneous layer, and the cornea was carried out in the elastic media. Two versions are considered: discounting the curvature (circular plate or plate) and with account of the curvature (spherical dome or shell). The work objective is to study the stress-strain state of the keraprosthesis and cornea in the contact area.

Materials and Methods. Mathematical models of the structures under consideration are the boundary value problems of the linear elasticity theory. The analytical solution is constructed for a simplified model in the form of a composite circular plate. Spatial three-dimensional problems and axisymmetric problems are solved by the finite element method. Finite element modeling of the considered structures was performed in the CAE package ANSYS and ACELAN. Results. CAD models of keratoprostheses with conditions of fixing and loading are constructed. The load acting on the keraprosthesis under the effect of intraocular pressure was determined. The stress-strain state of the keratoprosthesis and cornea elements was calculated. Special attention was paid to the area of its contact with the keratoprosthesis.

Discussion and Conclusions. The results of calculating the axial displacements and mechanical stresses in the first type of keratoprosthesis show that the selected geometric parameters meet the kinematic and strength requirements. The proposed models of the deformed state of soft biological tissues provide assessing their injury when using a keratoprosthesis of the second type, as well as selecting the geometric parameters and gradient properties of the intermediate layer.

Introduction. A new approach to the formation of the methodological basis of system analysis in the application to the problems on mechanical oscillatory structure dynamics is considered. The study objective is to develop a method forevaluating properties of the mechanical oscillatory systems with account for viscous friction forces based on frequency functions and damping functions that depend on the so-called coefficient of connection forms, which is the ratio of characteristics of generalized coordinates.

Materials and Methods. The graphoanalytical methods used for evaluating the dynamic properties of mechanical oscillatory two-degree-of-freedom systems are based on determining the extreme values of the frequency functions and the damping function, which are determined from the relations between the kinetic, potential energy and the values of the energy dissipation function. Mathematical models are based on Lagrange formalism, matrix methods, and elements of the theory of functions of a complex variable.

Results. A method is proposed for constructing frequency functions and damping functions for a class of mechanical oscillatory two-degree-of-freedom systems based on the analytical expressions that reflect features of the ratio of the potential and kinetic energy of the system considering viscous friction forces represented by the dissipative function. General analytical expressions for the frequency function and the damping function are derived. Graphoanalytical analysis of extreme properties of the corresponding frequency functions and damping functions is performed for mechanical vibrational systems with elastic-damping elements with symmetry properties. The results of numerical experiments are presented. A criterion for classifying frequency functions and damping functions based on the topological features of the graphs of the corresponding functions is proposed.

Discussion and Conclusions. The developed method for constructing frequency functions and damping functions can be used to display the dynamic features of mechanical oscillatory systems. The proposed matrix method for constructing a frequency-damping function for a two-degree-of-freedom system can be extended to the mechanical vibrational systems considered in different coordinate systems.

Introduction. A technique of solving the problem on an infinite plate lying on an elastic base and periodically loaded with a force that moves along an arbitrary closed trajectory and according to an arbitrary law; is considered.

Materials and Methods. An original method for solving problems on the elasticity theory for plates loaded with a force moving arbitrarily along a closed trajectory of arbitrary shape is considered. The problem on an infinite plate lying on an elastic foundation is investigated. The plate is loaded with a normal force moving at a variable speed. The load is decomposed into a Fourier series on a time interval whose length is equal to the time of its passage along the trajectory. The solution to this problem is realized through a superposition of solutions to the problems corresponding to the load defined by the summands of the specified Fourier series. The final problem solution is presented in the form of a segment of the Fourier series, each summand of which corresponds to the solution to the problem on the action on an infinite plate of the load distributed along a closed trajectory of the force motion. The fundamental solution to the vibration equation of an infinite plate lying on an elastic foundation is used to construct these solutions.

Results. A solution to the problem of an infinite plane, along which a concentrated force moves at a variable speed, is presented. A smooth closed curve consisting of arcs of circles was considered as a trajectory. The behavior of displacements and stresses near the moving force is investigated; and the process of the elastic wave energy propagation is also studied. For this purpose, a change in the Umov-Poynting vector is considered.

Discussion and Conclusions. The results obtained can be used in calculations for road design. The study of the propagation of the energy of elastic waves from moving vehicles will provide the assessment of the impact of these waves on buildings located near the road. Analysis of the behavior of displacements and stresses near the moving force will allow assessing the wear of the road surface.

Introduction. The design technique for a highly efficient technological process of vibration finishing of parts with small grooves and holes is presented. The decision is based on the selection of the granulometric characteristics of the processing environments. The cross-sectional shape and geometrical dimensions of burrs on typical parts of radio electronic equipment (REE) are analyzed. A generalized burr model has been developed. Methodological principles for the selection of particle size characteristics of operating environments are determined.

Materials and Methods. The new classification and coding according to the constructive and technological principles of REE components will provide reasonable selection of the equipment, environments and modes when designing their finishing process.

Results. A technique has been developed for selecting the granulometric characteristics of operating environments with the account of the major technological problems. Based on the design and technological features of the REE components, the dependences are proposed for determining the size and shape of the processing granules. The acceptance criteria for evaluating the results of vibration processing are determined. It is noted that one of the major tasks in the vibration processing of parts with small grooves and holes is to provide such in-process time at which burrs are removed, and the roughness and other surface parameters meet the technical requirements. In this case, the accuracy of the linear dimensions of the processed surfaces should be considered an indicator of quality. Quantitatively, this criterion is assessed on a specific index whose calculation considers the largest actual size before vibration processing, the burr height, the smallest allowable size after processing, and the tolerance established by the technical requirements. The process efficiency criterion is defined as the ratio of the machinability index to the processing time of a batch of parts or the cycle time per part. The proposed criterion enables to compare treatment processes under validating the solution to technological problems.

Discussion and Conclusions. The study results enable to confirm that vibration processing in the organic environment contributes to the effective removal of burrs and edge smoothing of small-sized parts of electronic equipment with small grooves and holes.

Introduction. The technological features of the processing crankshafts by the vibration shock method of surface plastic deformation (SPD), which is widely used in the technology of manufacturing machine parts, are considered. Theresearch objective is to justify the efficiency of the influence of vibration shock hardening treatment on improving the quality and performance of crankshafts (CS).

Materials and Methods. The methodological studies included the validation of the vibration shock processing flowchart and the development of an analytic model for assessing the effect of processing on the change in the macrogeometry (warpage) of the CS.

Results. Flowcharts have been developed for volumetric vibration shock finishing and hardening treatment of CS using a vibratory machine with a U-shaped work chamber. Its overall dimensions measure alike or exceed the overall dimensions of the CS being processed, and ensure the location of the shaft in such a way that its main axis, coinciding with the axis of the main bearing journals, is in the zone of the conditional axis of working mass rotation. The surface quality parameters were investigated during their processing on the UVG 4X10 vibratory unit according to the proven techniques using the dedicated tooling. It has been established that the vibration shock hardening treatment (ViHT) enables, due to plastic deformation of microroughness, to obtain a qualitatively new surface microrelief and to reduce its initial roughness, to drastically increase the surface microhardness of the CS main and rod journals; at that, it changes the stressed state of their surface layer. A calculated dependence is proposed to assess the total warpage of the CS strengthened under the ViHT, and its adequacy is confirmed. It is shown that the warpage of the shaft after the ViHT is due to the different tension of the rod and main journals of the CS at the level of К_н ≈ 0.6.

Discussion and Conclusions. Vibration shock treatment of CS provides an improvement in the geometric and physicomechanical parameters of surfaces of the rod and main journals. As a result of processing all surfaces of the shaft, warpage does not exceed the permissible values established by the technical requirements. So, we can conclude on the efficiency of the considered method of hardening CS with the aim of increasing their operational properties.

Introduction. The study results on the single interaction under the centrifugal rotary part machining in the abrasive discrete medium are presented. Simultaneously with the numerical simulation, experiments were carried out on a centrifugal-rotary unit, and the maximum depth of penetration into the surface of the part, the single-track sizes, metal removal in one blow of an abrasive granule, were investigated. The removal of metal from workpieces was investigateddepending on the processing modes, characteristics of the abrasive particle and the processed material.

Materials and Methods. The dependences for determining the metal removal from workpieces (steels 45, copper Cu-OF, and aluminum alloy D16T) are taken into account depending on the grain size (N3) of abrasive particles. The process of a single interaction of an abrasive particle and the workpiece surface is considered within the framework of the dynamic contact problem of the elasticity theory. The authors have carried out finite element modeling of the considered structures in CAE ANSYS package.

Results. The results of theoretical and experimental studies on the metal removal from workpieces depending on the grain size of abrasive particles are presented. The technique of their implementation, the tool and equipment used are described. The results of theoretical and experimental studies are compared. Their fine precision is established. Abrasive tools and processing modes are selected.

Discussion and Conclusions. The dependences constructed in the work provide determining the rational values of the technological parameters of the centrifugal rotary machining (CRM) process. They can be used under designing the CRM processes. Therefore, time and financial resources can be saved to achieve the desired surface quality.

Introduction. When administering complex multi-parameter systems, management decisions are often made under uncertainty. There is an acute problem of reduction of the likelihood of unwanted events and mitigation of possible damage. The efficiency of predicting damage to complex systems depends directly on the quality of processing methods, systematization, and the amount of input data. It is required to improve methods for assessing and predicting damage and to develop new approaches and criteria for statistical forecasting of damage and evaluating the system reliability. The solution to such problems is complicated by a large number of indicators, data uncertainty, short series of observations, incomplete initial information, insufficiently developed scientific methodological apparatus. Existing methods for predicting damage in the systems of potentially dangerous objects do not take into account the causes of accidents that happened due to unfavorable circumstances. As a consequence, management decisions are made upon unreliable forecasting results. In this regard, an urgent scientific task is the development of methods and techniques for the formation of viable management decisions, free from this shortcoming. The major study objective is to consider a particular problem for predicting damage due to unfavorable circumstances associated with the indistinguishability of the initial data. The tasks are to consider this kind of uncertainty which includes indistinguishability of the true system condition and the real value of its quantitative characteristics; to formulate a combinatorial problem for the case when a rather dangerous composite feature is determined by the joint manifestation of two or more simple features.

Materials and Methods. Under the conditions of multiple indistinguishability, the following was used as the source data: a set of indistinguishable outcomes with reliable information on the event instance and the uncertainty of assigning the event to a certain type; a family of sets having the same number of elements. The Cartesian product of the families of the corresponding sets and the actual value of the group of a compound potentially dangerous factor with a compound rather dangerous feature are taken into account. The resulting mono-element fuzzy group is presented, which is also a possible event resulting from the intersection of two necessary events.

Results. It is established that the problem of predicting damage due to unfavorable circumstances corresponds to a combinatorial-type problem, which consists in enumerating all sets of arguments. The resulting range, which is an elemental group of indistinguishability, characterizes the smaller and larger possible values of the size of the group of a potentially dangerous factor with a composite rather dangerous feature. It is shown that the formulated combinatorial problems without significant changes are applicable to problems in a generalized form, when composite rather dangerous features are determined using not only the operation of intersection, but also uniting and difference; thereby, the initial groups are not necessarily the objects with simple features.

Discussion and Conclusions. The results obtained are focused on the construction of analytical algorithms for establishing indistinguishability under the monitoring, modeling, forecasting state-related processes and complex dynamic multiparameter objects.

Introduction. The field of augmented reality (AR) is growing rapidly and has great advances in interaction, navigation and tracking. Nowadays there are a lot of trends for AR applications in different areas (education, entertainment, business, medicine, etc.). However, there is a lack of research to provide the evaluating AR apps framework to support developers when creating suitable AR applications for specific needs. We provide a practical approach to quantify some of the AR applications features. We focus on the development of criteria for evaluating augmented reality applications. We discuss the criteria of choosing dimensions for that space such as standards for AR, tools for AR development, navigation and tracking, content management, usability. We provide analysis and evaluation of AR apps through each characteristic using guidelines which we have developed.

Materials and Methods. An AR application is a software application that integrates digital visual, audio and other types of content into a real-world environment. The software quality and performance are the main characteristics of the application, which are key factors for AR applications. The analysis of scientific papers, documents and standards made it possible to determine characteristics that are the most significant quality indicators based on well-grounded users’ needs and demands.

Results. The criteria we have developed for evaluating applications with augmented reality enable developers to create their own software products in stages, based on step-by-step requirements for them, evaluating the development process by characteristics. This approach will allow you to create high-quality software products using standardized, modern development tools.

Discussion and Conclusions. In addition, developers will have a detailed understanding of each stage of creating the application and the necessary development tools and technologies to obtain the highest quality result. That will give an opportunity to decide on specific development tools, methods, models and technologies before starting work on a project. As a result, it will provide the final high-quality software product with good extensibility and compliance with the modern requirements of the digital industry market.

Introduction. Verification packages design and analyze the correctness of parallel and distributed systems within the framework of various classes of temporal logics of linear and branching time. The paper discusses a polynomially realizable class of ∆₀T -formulas interpreted on multi-sorted models with hierarchical suspensions. The suspensionstructure is described by an arbitrary context-free (CF) grammar. The predicates and functions of the model signature are interpreted on the original CF-list, which is completed during the interpretation process.

Materials and Methods. A constant model is constructed for theories from ∆₀T-quasiidentities with Noetherian and confluence properties. We consider formulas of the multi-sorted first-order predicate calculus (PC) language with variables of the “list” sort interpreted on models with a hierarchized suspension. The theory is interpreted in terms of grammar inference trees describing the behavior of the specified system. The CF-grammar rules hierarchize the action space of the modeled system. It is noted that the expressive capabilities of Д0T-formulas are insufficient for modeling real-time systems. Therefore, expressions with unbounded universal quantifier V, known as PT formulas, are used for the specification.

Results. The logical specification of an automated complex which consists of a workpiece manipulator is given as an example. The location of the positions is fixed by sensors. The operating cycle of the manipulator is described. The specification of its operation consists in the hierarchization of actions by the rules of the CF-grammar and their description by the first-order PT-formulas taking into account the time values.

Discussion and Conclusions. The paper shows that the class of the considered formulas can be used to model real-time systems. An example of the logical specification of a manipulator behavior control device is given.

Introduction. Electronic document management systems (EDMS) are used to store, process and transmit large amounts of information. Automation of these processes is a challenge that requires a comprehensive solution. Its solution willreduce the time and material costs for design and make the transition to a more advanced, adaptive EDMS. The paper is devoted to the development of new methods for automating the process of distributing information in the EDMS. The work objective is to improve the accuracy of the information distribution in the EDMS through moving from analytical or algorithmic solutions to the use of new methods based on machine learning technologies. The application of neural networks in the furtherance of this purpose will also improve the efficiency of software development through automating the analysis and processing of information.

Materials and Methods. A new method of the automated information distribution based on machine learning technologies including a mathematical description of the information distribution rules is proposed. The formulated list of conditions for the information distribution provides the implementation of software based on neural networks for solving the problem of automatic data distribution in the EDMS.

Results. The method of automated information distribution has been tested on the example of the EDMS subject area when solving the problem of analyzing the correctness of information entered by the user. In the course of experimental studies, it was found that the proposed method, based on machine learning technologies, provides better accuracy (8 % higher) and is more efficient (in accordance with the Jilb metrics and cyclomatic complexity).

Discussion and Conclusions. The results obtained confirm the efficiency and accuracy of the method proposed. The presented results can be used to automate the processes of distribution and verification of information in adaptive EDMS, as well as in other information systems. Based on the method developed, it is also possible to solve connected problems: search for duplicates and similar documents, classification and placement by file categories.

Introduction. This work is aimed at solving the problem of phytoplankton dynamics in the coastal environments using the example of the Azov Sea. This takes into account the transformation of forms of phosphorus, nitrogen and silicon, as well as the aquatic medium motion, the distribution of temperatures and salinities over the sea area. River flow, varying in volume and chemical composition, affects significantly the variability of hydrophysical and biogeochemical parameters of the processes occurring in the coastal environment. This explains the need for statistical processing of the data from long-term observations over the river flow characteristics.

Materials and Methods. The mathematical model of biogeochemical cycles is based on a system of non-stationary equations of the convection-diffusion-reaction of parabolic type with nonlinear functions of sources and lower-order derivatives, to which the corresponding initial and boundary conditions are added. In the course of statistical analysis of the series of long-term observations over river flows, the values of the following indicators were found: skewness coefficient, degree of kurtosis, variance and standard deviation, coefficient of variation, autocorrelation coefficient, Neumann ratio, and Anderson criterion.

Results. The statistical analysis of the series of long-term observations over the hydrochemical indicators of the Don river suggests heterogeneity of the field data. This is due to the stochasticity of nutrient inputs and the volume of freshwater flow to the sea as a result of natural and anthropogenic factors. Field data should be correlated with seasonal changes in the aquatic environment temperature. This paper presents the results of a computational experiment to model the dynamics of phytoplankton populations in summer season, when temperatures are favorable for their reproduction and growth. The proposed mathematical model considers the spatially inhomogeneous distribution and transformation of forms of phosphorus, nitrogen, and silicon, as well as changes in salinity, temperature, and motion of the aquatic environment.

Discussion and Conclusions. The multispecies mathematical model of the dynamics of phytoplankton populations is considered with account for the transformation of forms of phosphorus, nitrogen, and silicon in the coastal environments. The analysis of data from field observations, for which its major statistical parameters are calculated, is carried out. As a result, it is concluded that data of the long-term observations are significantly variable. This is due to two reasons. Random nature of the input of nutrients and the volume of river flow as a result of anthropogenic factors is the first reason. The second reason includes the alternation of relatively high-water and low-water periods for fresh flow over the last 12-15 years. The hydrological regime is changing mainly due to the reduction of the average annual freshwater flow of the Don and partly of the Kuban. This trend is likely to increase due to climate changes, as well as with further regulation of the Don river flow after the Bagaevsky hydroelectric installation start-up. Numerical experiments based on the field data confirmed the predictive validity of the developed models and programs. They can be used to predict change in the composition and abundance (concentrations) in the Azov sea core planktonic populations, which define, on the one hand, food resources, and, on the other hand, the aquatic environment in terms of the ongoing sea salinization.