Semi-Markov Model of the System of Repairs and Preventive Replacements by Age of City Buses

The paper presents a mathematical model of the system of repairs and preventive replacements by age of city buses. The mathematical model was developed using the theory of semi-Markov processes. In the model developed, four types of city bus renewal processes are considered and three types of corrective repairs and preventive replacement. Corrective repairs are considered in two types: minimal repairs (repairs carried out by the Technical Service units) and perfect repairs (repairs carried out at the stations of the Service Station). The models of restoration systems that use semi-Markov processes in which minimal repairs, perfect repairs, and preventive replacements by age, have been examined in the literature to a limited extent. The system under consideration is analysed from the point of view of two criteria: profit per time unit and availability of city buses to carry out the assigned transport tasks. Conditions of criterion functions’ extremum (maximum) existence were formulated for the adopted assumptions. The considerations presented in the paper are illustrated by exemplary results of calculations.

EXPERT DECISION-MAKING SYSTEMS

An approach to making complex technical and economic decisions is proposed in cases where there is insufficient (or no) information about the experimental statistical data necessary for the construction of regression models of criterion functions. The situation is aggravated when a decision is made according to several conflicting quality criteria. In conditions of an acute shortage of experimental data, it is proposed to obtain the necessary information («quasi-experimental» data) from experts - specialists with sufficient experience in making decisions for the class in question. A qualified specialist (expert) with sufficient experience in making decisions for this class can perform a thought experiment. He must imagine what, in his opinion, the levels of criterion functions will be at various reference points of factors. The method is based on an individual opinion (postulate), expressed by a specialist-expert about the estimated value, based on his professional experience. To assess a certain quantitative characteristic, the postulates of not one, but several persons competent in this issue are used. It is assumed that the «true» value of the unknown quantitative characteristic is within the range of expert assessments and the «generalized» collective opinion is more reliable. To solve the problem under consideration, a multicriteria optimization approach is taken using a nonlinear trade-off scheme. This study makes it possible to identify the main trends in the development of multi-criteria decision-making systems in the absence (or lack) of experimental data. A model example is given.

Development of a Power and Communication Bus Using HIL and Computational Intelligence

This paper deals with the development of a power and communication bus named DLN (Device Lightweight Network) that can be seen as a new interface with auto-addressing functionality to transfer power and data by means of two wires in modern cars. The main research goal of this paper is to elaborate a new method based on a hardware in the loop technique aided by computational intelligence algorithms in order to search for the optimal structure of the communication modules, as well as optimal features of hardware parts and the values of software parameters. The desired properties of communication modules, which have a strong influence on the performance of the bus, cannot be found using a classical engineering approach due to the large number of possible combinations of configuration of the hardware and software parts of the whole system. Therefore, an HIL-based optimization method for bus prototyping is proposed, in which the optimization task is formulated as a multi-criteria optimization problem. Several criterion functions are proposed, corresponding to the automotive objectives and requirements. Different soft computing optimization algorithms, such as a single-objective/multi-objectives evolutionary algorithm and a particle swarm optimization algorithm, are applied to searching for the optimal solution. The verification study was carried out in order to show the merits and limitations of the proposed approach. Attention was also paid to the problem of the selection of the behavioural parameters of the heuristic algorithms. The overall results proved the high practical potential of the DLN, which was developed using the proposed optimization method.

Computational Diagnostics of Jacobi Unstable Dynamical Systems with the Use of Hybrid Algorithms of Global Optimization

The study focuses on the problems of restoration and analysis of free parameters of dynamical systems from indirect, approximately given information. In the context of the Kosambi --- Cartan --- Chern theory, a geometric description of the time-evolution of the system is introduced. Five geometric invariants are determined for the system under study. The eigenvalues of the second invariant estimate the Jacobi stability of the system. Such a study is of interest in practical applications, where it is required to identify the regions in which both Lyapunov stability and Jacobi stability occur simultaneously. The inverse problem of computational diagnostics of the system is formulated for approximately given eigenvalues of the second invariant. The solution to the regularized inverse problem is determined using an optimization approach. Scalar criterion functions are assumed to be continuous, multidimensional, locally Lipschitzian, and not necessarily everywhere differentiable. When searching for global solutions, we used new hybrid algorithms that integrate stochastic algorithms for scanning the space of variables and a deterministic local minimization procedure. The numerical scanning procedure is implemented with the use of two modified versions: quasi-opposition-based and rotation-based learning mechanisms. In the phase of local search, two-parameter smoothing approximations of criterion functions are introduced. Examples of solving problems of computational diagnostics of Jacobi unstable dynamical systems are given: the Lorentz system and a controllable elliptical pendulum

Method of Restrictions in the Multicriteria Task of Allocation of Flows

In article the new approach to the decision of the multicriteria task of formation of resources of a transport communication network based on a combination of one of methods of multicriteria optimization ‒ a method of restrictions and a simplex a method is offered. The task is decomposed also dares stage by stage. At the first stage the set of ways of an admissible rank is formed. On the second calculation structural reliabilities of the set of ways generated at the first stage is produced. At the final stage the choice optimal on the criterion functions characterizing cost and carrying capacity, set of ways of transportation of flows corresponding pairs of nodes which is reduced to the decision of the multicriteria task of formation of resources of a transport communication network by a method of restrictions is carried out.

Optimisation of the Topping-Up Process of Lubricating Oil in Medium-Speed Marine Engines

In this paper, we examine the problem of optimising the process of topping up lubricating oil in medium-speed marine engines. This process is one of the methods that can be applied to improve the properties of lubricating oil. The amount of fresh oil added to lubricating oil system always balances its consumption, but the method used to top up depends on the marine engineer. Small amounts of fresh oil can be added at short intervals, or large ones at long intervals, and the element of randomness often plays a significant role here. It would therefore be valuable to find a method that can help the mechanical engineer to choose the right strategy. We apply a multi-criteria optimisation method for this purpose, and assume that the criterion functions depend on the concentration of solid impurities and the alkalinity, which are among the most important aspects of the quality and properties of lubricating oil. These criterion functions form the basis for multi-objective optimisation carried out with the use of the MATLAB computer program.

Electricy Losses Management in Distribution Network as a Composition of Automated Meter Reading and Control System (AMRCS)

The problem of electricity losses management in distribution electric networks (DEN) operating in conditions of asymmetry of currents and voltages is reviewed. As it is known, the asymmetry factor leads to significant losses of active power and, as a result, decreases the efficiency and technical and economic indicators of the DEN. The purpose of the control is to minimize technical energy losses in the distribution network based on the creation of an automatic control system (ACS) for the process of balancing a three-phase network in the composition of automated meter reading and control system (AMRCS). The latter are currently being widely implemented to automate information processes in DEN. However, AMRCS does not include in its composition technologies designed to solve the problem under review. A method is proposed for constructing a digital ACS controller, the main function of which is to maintain phase currents at the network input at a given level in real time. The concept of the method is based on the idea of the desired redistribution of electricity flows between the phases of the distribution network by appropriate switching of single-phase consumers (customers) so that the minimum spread of phase currents from their specified level is ensured. To achieve the goal of control, criterion functions are constructed that determine the qualitative indicators of the functioning of the ACS. Algorithms for the functioning of the digital controller and the formation of control actions on the subject have been developed. The latter are a digital code containing data on the coordinates of electricity meters of consumers of a three-phase network to be switched to another phase.

Stability kernel of vector optimization problems under perturbations of criterion functions

The article is devoted to the study of the influence of uncertainty in initial data on the solutions of optimiza-tion multicriterial problems. In the optimization problems, including problems with vector criterion, small per-turbations in initial data can result in solutions strongly different from the true ones. The results of the con-ducted researches allow us to extend the known class of vector optimization problems, stable with respect to in-put data perturbations in vector criterion. We are talking about stability in the sense of Hausdorff lower semicontinuity for point-set mapping that characterizes the dependence of the set of optimal solutions on the input data of the vector optimization problem. The conditions of stability against input data perturbations in vector criterion for the problem of finding Pareto optimal solutions with continuous partial criterion func-tions and feasible set of arbitrary structure are obtained by studying the sets of points that are stable belonging and stable not belonging to the Pareto set.

Binary response models comparison using the 𝛼-Chernoff divergence measure and exponential integral functions

In this paper, the families of binary response models are describing the data on a response variable having two possible outcomes and p p explanatory variables when the possible responses and their probabilities are functions of the explanatory variables. The α \alpha -Chernoff divergence measure and the Bhattacharyya divergence measure when α = 1 / 2 \alpha = 1/2 are the criterion functions used for quantifying the dissimilarity between probability distributions by expressing the divergence measures in terms of the exponential integral functions. The dependences of odds ratio and hazard function on the explanatory variables are also a part of the modeling.

ALGORITHMS FOR CONSTRUCTING CRITERIA FUNCTIONS OF THE FINANCIAL EQUILIBRIUM OF A COMMERCIAL ORGANIZATION

В статье, продолжающей изложение методики анализа финансовой устойчивости коммерческой организации в рамках новой парадигмы анализа, рассмотрены возможности дедуктивно-аксиоматического обоснования алгоритмов построения критериальных функций финансового равновесия, являющихся необходимым элементом указанной методики. Предлагаемая концепция финансового равновесия основывается на общенаучных представлениях о равновесном состоянии системы. В качестве важных примеров представлены критериальные функции финансового равновесия, вытекающие из норм права, регулирующих условия несостоятельности (банкротства) и ликвидации коммерческих организаций. Предложен общий алгоритм классификации финансовых ситуаций, основанный на распределении рисков неплатежеспособности и ликвидации коммерческой организаций по возможным ситуациям и отражающий данное распределение с помощью значений критериальных функций. In the article, which continues the presentation of the methodology for analyzing the financial stability of a commercial organization within the framework of a new paradigm of analysis, the possibilities of deductive and axiomatic justification of algorithms for constructing criterion functions of financial equilibrium, which are a necessary element of this methodology, are considered. The proposed concept of financial equilibrium is based on general scientific ideas about the equilibrium state of the system. As important examples, the criteria of the financial equilibrium functions arising from the rules of law governing the conditions of insolvency (bankruptcy) and liquidation of commercial organizations are presented. A general algorithm for classifying financial situations is proposed, which is based on the distribution of risks of insolvency and liquidation of commercial organizations by possible situations and reflects this distribution using the values of criteria functions.