Using correlation matrices in predicting airline performance

The article considers the issue of making forecasts of the main indicators of the activities of airlines for their effective functioning in the air transportation market. It describes the life cycle of airlines and provides a classification of the forecasts that are currently being made. The interrelation of correlations of the key parameters of the airline’s functioning is considered, the use of correlations in forecasting is shown, actual calculations are presented, and a significant increase in forecast accuracy when using this forecasting method is demonstrated.

Methodology for selecting installation sites for automatic power redundancy systems of DC traction substations

The paper presents a method for selecting the installation locations of power reservation systems of traction substations to reduce electricity losses in the system of traction power supply of DC railways. The analysis of the main criteria affecting the efficiency and reliability of the DC traction power supply system is carried out. The algorithm for selecting the installation locations of power reservation systems has been developed, which allows selecting traction substations that provide the greatest energy effect during the installation of systems

Changes in structural-phase state and physicochemical properties of tungsten-free TIC-TiNi hard alloys after various types of ion-beam treatment

Using experimental methods of analysis, the morphology, elemental composition and chemical state of hard alloys of the «TiC-TiNi» system in the initial state and after various types of ion-beam treatment have been investigated. It is found that the effect of a continuous ion beam leads to an increase in the microhardness of the investigated alloys by 10–12 %. When samples are irradiated with a pulsed ion beam, as a result of destruction of surface layers, the microhardness value decreases by 20 %, as a result of which this type of modification is not preferable for alloys of the TiC-TiNi system

Investigation of performance properties of rubber with metal fillers

The work conducts laboratory tests on the rubber of the first group of GOST 8752-70 with the introduction of the metal components. The filler is introduced into the rubber mixture on laboratory rollers. Fine powders of copper (Cu), tin (Sn) and lead (Pb) are used as fillers. The dependences of the temperature in the contact zone of the sample and the body of revolution on the concentration of the filler and the dependence of wear on the concentration of the filler for the same loads and sliding speeds are obtained, the fillers that give the rubber the greatest wear resistance are revealed, and the rational amount of the filler is determined. The positive results of laboratory tests give grounds to recommend various equipment including aerospace equipment for use in sealing devices of hydraulic systems, rubber products with metal fillers in the indicated concentrations, which will extend their service life and increase their reliability

Methodology for determining permissible operating modes of DC traction motor of quarry dump truck to ensure satisfactory commutation

The article considers an approach to determining the permissible ranges of changes in the armature voltage, armature current and the excitation coefficient of the DC traction motor of a mining dump truck to ensure satisfactory commutation. When the DC motor is running in the specified modes, the probability of sparking in the collector-brush unit with a degree of 2 points will be minimal. A method for determining the permissible operating modes of a mining dump truck traction motor to ensure satisfactory commutation is proposed. The method allows, based on the analysis of experimental data, to determine the permissible ranges of changes in voltage, armature current and excitation coefficient, at which the degree of sparking does not exceed 1½ points

Analysis of conditions and criteria for shock pulse reproducibility on mechatronic test stands

Repeated impact testing is an important part of any product development. The tests are carried out on stands of repeated blows. In order to expand the range of functional parameters of mechatronic stands of multiple blows, the following are proposed: criteria for choosing the parameters of an air suspension, a method for predicting changes in the stiffness of a shaper during stand operation, and a method for assessing the effect of the reproducibility of controlled parameters on the stability of a shock pulse. In contrast to the known works, the proposed criteria and methods take into account the requirements for the reproducibility of the shock impulse

Development of human lower limbs exoskeleton robot for medical rehabilitation

The article deals with the solution of the problem of optimizing the characteristics of controlled motion of human lower limb exoskeleton robot for improving medical rehabilitation. The aim of the work is to develop a rehabilitation device capable of providing controlled motion in two planes, as well as maintaining balance without loss of mobility. The design and control system of a rehabilitation trainer designed for performing mechanotherapy of the lower limbs of patients with locomotive disorders are proposed and characterized. The developed system has a number of significant differences from analogues and can be recommended for experimental research on patients with impaired locomotive functions

The active dynamic vibration damper in non-stationary operation of a vibroactive unit

The paper considers a vibration isolation system, in which a force is applied to the moving mass of the active dynamic vibration damper by an actuator in proportion to the measured value of the base response. The amplitude-frequency and impulse characteristics are plotted depending on the parameters of the system, assuming the actuator without distortion generates the force proportional to the base response. It is shown that the considered vibration isolation system is quite effective in the low-frequency region, including in the resonance region of the passive system, both in stationary and nonstationary modes of vibroactive forces

Research of partial discharge characteristics features in bushings

The paper is devoted to partial discharge measurement and analysis in switchgear bushings. PD bushing structure analysis is described to assess possible defect sources in bushings. An experimental 10 kV bushing sample with the natural defect is obtained from the bushings’ manufacturer. It is tested using the PD measurement technique. Test results showed significant PD intensity at voltages from 12 kV and higher. We have an assumption that a part of registered discharges occurred in the air close to the high voltage electrode sharp edges. To check this assumption we grind them off and repeated the test. The second test does not show considerable PD characteristics change. Therefore, we assume that the bushing sample has an inner defect because the bushing’s surface is not contaminated to generate surficial discharges. The bushing is researched by a destroying method for defect localization. However, inside the bushing, possible defect locations are not found. It might be connected with the fact that the defect could not be found visually at the test time or the defect is located in the gasket between the high voltage electrode and insulator’s body. Besides, there are determined features of phase-resolved partial discharge patterns in switchgear bushings.

Detection acoustic signals of partial discharges on defects in high voltage insulation

The article is devoted to the method of acoustic registration of partial discharges in high-voltage insulators. Physical processes of generation of various types of partial discharges in high-voltage insulators are considered. The instrumental implementation and method of processing diagnostic information from sensitive elements — acoustic receivers of the ultrasonic range are described. The ability to detect sources of partial discharges with reference to the place of origin is important for localizing a faulty element and its further diagnosis.