Vol 27, No 1 (2021)

The exact algorithm that implements the Branch and Bound method with precomputed tour which is calculated by Lin-Kernighan-Helsgaun metaheuristic algorithm for solving the Traveling Salesman Problem is concerned here. Reducing the number of decision tree nodes, which are created by the Branches and Bound method, due to a "good" precomputed tour leads to the classical balancing dilemma of time costs. A tour that is close to optimal one takes time, even when the Lin-Kernighan-Helsgaun algorithm is used, however it reduces the working time of the Branch and Bound method. The problem of determining the scope of such a combined algorithm arises. In this article it is solved by using a special characteristic of the individual Traveling Salesman Problem — the number of changes tracing direction in the search decision tree generated by the Branch and Bound Method. The use of this characteristic allowed to divide individual tasks into three categories, for which, based on experimental data, recommendations of the combined algorithm usage are formulated. Based on the data obtained in a computational experiment (in range from 30 to 45), it is recommended to use a combined algorithm for category III problems starting with n = 36, and for category II problems starting with n = 42.

A new technique is described, used by the authors to automate the design process of the main drive of a new generation machine intended for industrial washing of fruits and vegetables. To solve the problem of multi-criteria design, the original approach is proposed that uses interconnected mathematical models describing the dynamic behavior, strength reliability and functional characteristics of the machine in a unified information space. The generalized mathematical model includes 12 controlled parameters, 16 functional constraints, and 3 quality criteria. A genetic algorithm was used to find the space of Pareto-optimal solutions. The situational approach was used to select the final rational solution from a set of solutions belonging to the Pareto-optimal domain. The rational design of option the washer found using the proposed approach is compared with the existing ones. The proposed design methodology can be recommended for the design of a wide range of similar mechanical structures.

The synthesis of latent features is considered in order to reduce the size of the space for describing objects of disjoint classes K₁, K₂. A condition is proposed for the sequential formation of feature sets X(h) ⊂ X(n), 2 ⩽ h ⩽ n for linear display of object descriptions from X(h) to R². Latent features are synthesized from data obtained as a result of preprocessing the values of the initial features. Preprocessing is realized through normalization in [0,1] and data transformation that is invariant to the scales of feature measurements. The correspondence structures of objects in X(h) and R² are investigated according to the results of data preprocessing and grouping. A measure of compliance of two structures of relations of objects in different features spaces is proposed. The measure of compliance is calculated by splitting the objects of classes into disjoint groups. When splitting into groups, the relation of connectedness of class objects by a defined set of hyper balls is used.

This paper presents a technological approach to the organization of a unified data exchange between heterogeneous systems based on the formation of unified representation of data structures. The formal and conceptual models of unified data exchange are presented here. There is proposed the software architecture that provides unified data exchange. Elements of the technological approach are considered in the case of orders for state and municipal needs.

This paper devoted to research of indoors navigation problems under poor or insufficient quality of satellite navigational data environment. The problem of object positioning in 3D space by Bluetooth devices located indoors forming a multi-position tracking system is considered in this research. Emphasized that in order to succeed for such system it is required to preestimate distinctive accuracy. The proposed model interpretation of the positioning problem as the system of linear equations. The classic model interpretation for method of least squares is used for resolution. General problem of linearization around reference resolution is the locality of its features. There are three concepts of problems solvability, such as fundamental solvability (observability), solvability in conditions of instrumental measurement errors and solvability under conditions of finite accuracy of computation on a computer. The first aspect of solvability is interpreted by the completeness of the rank of the corresponding system of linear algebraic equations, the second and third ones represents by the conditionality of the problem and the convergence of the iterative estimation procedure. The conducted experiments show that for the positioning problem the attributes of the linearized model are accurate enough to represent the original nonlinear problem. Such interpretation allows to build theoretical accuracy estimation priors for object coordinates evaluations and to identify the areas with insufficient positioning accuracy. In this paper there are results of expected accuracy evaluation for various system patterns with full-scale experiments proving the theoretical calculations. Experiments for problems with using SKYLAB Beacon VG01 Bluetooth transmitters and smartphone HUAWEI WAS-LX1 are presented and confirmed that math model with linear approximation defined by authors is usable for solving indoors navigation problems using Bluetooth signal. So, for good enough quantity and appropriate location of the tracks the achievable positioning accuracy could be as good as 0.2—0.3 meters for all three coordinates. Such accuracy allows to navigate small hovering objects such as drones. In general, it looks promising to use Bluetooth trackers for solving positioning problems for indoors environments.

The article presents the problem of analyzing the efficiency of maintenance and repair of complex technical equipment, shows a number of problem statements that reflect the problems of choosing the optimal service plan within the sequence of operations. The scalar and vector representations of the problem are considered, and a scheme for implementing an approach to evaluating the effectiveness of repair and maintenance plans is proposed.