Vol 15, No 1 (2021)

The subways of Moscow and St. Petersburg are the oldest in Russia. Its infrastructure includes a diverse fleet of equipment. The fleet of rolling stock in the last decade was mainly renewed, while due to the peculiarities of operation and mainly for financial reasons, the escalator fleet will not be replaced for a long time. In this connection, the main task of the departments responsible for the operation of escalators is to maintain the rapidly aging fleet in good condition. Thus, a situation, when the escalator economy is a source of costs to meet the constantly increasing demand for resources is formed. At the same time, the limited allocation of all types of resources only aggravates the current situation. The above circumstances contribute to the actualization of the issue of selection of tools, which makes it possible to increase the efficiency and safety of operation of underground tunnel escalators. According to the authors of the paper, one of such tools can be the forecasting of the technical state of the elements of the escalator subsystems, made on the basis of special routing of information flows, designed for the optimal distribution of allocated resources. Since an escalator is a complex technical object of increased danger, the routing of information flows for it characterizing its technical condition is possible only on the basis of a preliminary decomposition into information levels. For this reason, the beginning of the paper is devoted to the decomposition of the technical state of the escalator into four information levels, covering all aspects of the technical state from the micro-level of the state of materials from which the elements of the escalator subsystems are made, ending with the functional state of the entire escalator. The purpose of the work is further revealed. It consists in describing a general mathematical model for predicting the technical state of the elements of the escalator subsystems and the requirements for its construction. The work describes the main task that solves the proposed forecast model. In conclusion, the options for using the proposed model are considered. The scientific novelty of the proposed approach lies in the use of the modern mathematical apparatus of the fuzzy set theory for processing parametric information, elements of artificial intelligence, as well as a precedent approach in analyzing the operational situation, which, in combination, are necessary to build a predictive model of the technical state as applied to the escalator facilities of the subway. From a practical point of view, it should be noted that the proposed mathematical model, implemented on the basis of modern information technologies, will make it possible to more rationally adjust the mechanisms for allocating resources, while ensuring the necessary level of safety for passenger transportation.

In the case of hydraulic machines and devices, local hydraulic resistances, as a rule, constitute the determining part of the total head losses during the operation of any hydraulic machine. The most detailed reference book, which has gone through many editions in our country and published abroad, is the “Reference book on hydraulic resistance” by I.E. Idelchik. At the same time, the analysis carried out in the cited literature showed that, depending on the year of publication of the reference book by I.E. Idelchik, for the same local resistance, the difference in the numerical values of the same local hydraulic resistance can reach a multiplicity. The purpose of this work is to analyze the recommendations given in the handbook for calculating the hydraulic resistance coefficient of diaphragms (holes) with any edge shapes for various conditions of flow overflow in the transition and laminar regions inside a pipeline of constant cross-section. In particular, it is shown that tabular values are recommended for calculating the filling factor of the diaphragm section and an analytical dependence is given, the differences in the numerical values of which reach 15%, which introduces uncertainty in the results of specific calculations. To a much greater extent, a similar situation takes place when using the recommendations for calculating the coefficient of hydraulic resistance. In this case, also, the given numerical tabular values of the coefficients of hydraulic friction resistance when the flow passes through the hole and calculated from the given analytical dependence, differ in multiplicity, which indicates the absence of a connection between them. This issue requires further special consideration.

This article examines the main factors that determine the thermal performance of a spark plug in the temperature range from 300 to 2500 Kelvin. The optimal value of the temperature of the heat cone was determined. A technique and algorithms for the numerical simulation of the thermal state of a spark plug are presented. These made it possible to calculate the dependence of the thermal conductivity coefficient of ceramic elements of a plug and the specific heat capacity of ceramic insulator on temperature. The calculation of the working cycle in the engine cylinder was carried out. The calculation of the temperature distribution of heat fluxes in the elements of the spark plug design was performed. The assessment of the thermal characteristics of the spark plug is carried out by the method of numerical modeling of the operating cycle of an internal combustion engine. The calculation of the instantaneous temperature distribution in the body of the spark plug and on its surface is carried out. Calculations of the intensity of heat fluxes between the spark plugs and adjacent parts of the working fluid were carried out. The modeling of the operating cycle for various operating modes of the engine was made. The temperature fields of the spark plugs were determined. An array of initial data for calculating the temperature fields of the spark plug was formed. Dependences of the temperature of the working fluid in the vicinity of the spark plug on the angle of rotation of the crankshaft are determined. The harmonic components of the heat transfer coefficients between the working fluid and the cylinder fire guard (Voshni coefficient) are considered. The harmonic components of the heat flux density are considered. Calculations of the heat field of the spark plug are carried out for various operating modes of the engine, using the finite element method. The calculation of the temperature field of the spark plug by the finite element method was carried out using ANSYS, SolidWorks, Inventor, etc.

The ever-increasing demands of vehicle safety are forcing car manufacturers to develop ADAS systems (“intelligent assistants”). However, before starting sales of car equipped with such functions it is necessary to fully test and validate the algorithms for the operation of electronic systems in various conditions. Currently, the most popular methods for debugging and testing ADAS systems are based on "model-”, “software-" and "hardware-in-the-loop" modelling, which allows developers to identify and eliminate errors in the early stages of product development, thus saving money. Despite the enormous advantages of simulation, full-scale tests remain the fundamental and final stage before the start of mass production, this is due to the fact that international and Russia government standards currently don’t provide for the certification of “electronic assistants” through virtual tests. In this regard, manufacturers of measuring equipment and test-engineers are faced with the task of developing a new test setup that provides fixing the GNSS-position of vehicles in dynamic modes with centimeter accuracy, as well as making synchronized video recording. This article describes the approach of the employees of the NNTU n.a. R. E. Alekseev to the solution of this problem: the design of the concept and its implementation on a light commercial vehicle with ADAS systems. To fix coordinates with centimeter accuracy we have used Racelogic Vbox 100 Hz, operating in the RTK-mode, synchronized video recording was made using Racelogic Video Vbox Pro, which includes 4 wide-angle cameras. The approbation of the measuring installation was carried out when testing the following systems: a blind spot detector, a lane departure warning and a parking space search assistant. The article presents a number of graphs of the functioning of one of the systems.

This article considered the main issues of finding options for strengthening the roofing of the vehicle body based on topological optimization in order to meet the requirements of passive safety with a minimum mass. The method for achieving this goal was mathematical modeling using the Topology Optimization modules of the ANSYS software package and the explicit dynamics of LS-Dyna. In order to test the effectiveness of the reinforcements, the pillar side impact according to UNECE 135 “Uniform provisions concerning the approval of vehicles with regard to their performance in side impact on a pillar” was selected as the loading mode. The efficiency criterion was the energy intensity of the body, defined as the ratio of the energy of the system to the residual (plastic) deformation at the level of the center of the door. Based on the topological optimization, two variants of the arrangement of the reinforcing elements, practically equivalent in efficiency, were obtained. For the most complete assessment of the influence of the parameters, several options for strengthening the roofing were considered: placement of steel reinforcing elements; placement of foam aluminum under the roof; combination of steel elements with filling their cavities with foam aluminum. Based on the simulation results, a comparative assessment of the effectiveness of the considered amplification options was carried out. The most effective were the options for reinforcing the roofing with channel-shaped beams and filling them with foam and the option for reinforcing the roofing with channel-shaped beams and diagonal bridges in them, causing it to increase compared to the original structure by 20.88 and 19.94%, respectively, but at the same time the mass of the first option is 42 kg less than the mass of the second.