IMPROVEMENT OF METHODS OF TECHNICAL DIAGNOSIS OF PASSENGER RAILWAY CARS

Extension of the service life of a particular passenger railway car can be considered fully justified only if it is justified by the results of scientific and experimental research and approved by the relevant administrative documents of Ukrzaliznytsia the service life limit for wagons of this type. The existing method of technical diagnostics of passenger railway cars does not allow to fully assess the probability of extension of the service life of the car, because it does not take into account the peculiarities of damage to structural elements during operation. In the article the sequence of research of stresses in elements of a frame of a body of the passenger car of construction of KVN on the basis of standard tests is considered. The task of the study is to determine the sequence of calculation of stresses in the frame elements of the passenger car body of KСР (Kryukiv Carriage Plant) with a service life exceeding 41 years from the date of manufacture to assess strength and fatigue resistance by technical diagnostics and standard tests. It is concluded that the condition of the load-bearing metal structures of cars after long operation does not approach the limit. The residual resource was set at one of the minimum calculated values. If the results of calculations show that the resource is exhausted, the residual service life is determined by the results of bench tests for fatigue. The obtained practical and theoretical results make it possible to extend the service life of cars beyond that set by the manufacturer.

Search for topological defect dark matter with a global network of optical magnetometers

Ultralight bosons such as axion-like particles are viable candidates for dark matter. They can form stable, macroscopic field configurations in the form of topological defects that could concentrate the dark matter density into many distinct, compact spatial regions that are small compared with the Galaxy but much larger than the Earth. Here we report the results of the search for transient signals from the domain walls of axion-like particles by using the global network of optical magnetometers for exotic (GNOME) physics searches. We search the data, consisting of correlated measurements from optical atomic magnetometers located in laboratories all over the world, for patterns of signals propagating through the network consistent with domain walls. The analysis of these data from a continuous month-long operation of GNOME finds no statistically significant signals, thus placing experimental constraints on such dark matter scenarios.

Energy and Environmental Performance of Solar Thermal Collectors and PV Panel System in Renovated Historical Building

The major intent of this article was to determine the amount of energy received by two active systems used to convert solar radiation and to estimate their impact on reducing the emission of pollutants. Thermal solar collectors with an area of 51.36 m2 and photovoltaic panels with an area of 50.4 m2 were subject to comparative analysis. It was assumed that either of the two systems could be installed on the roof of an old tenement house located in Poznan (Poland), which is planned for renovation. Computer simulations made with DesignBuilder software were used as a research tool. Two main conclusions can be drawn from the analysis of the year-long operation of both systems in the conditions of a typical meteorological year. Thermal solar collectors can produce 469 kWh of heat from 1 m2 of the device annually, while PV panels can generate 136 kWh of electricity per year from 1 m2 of active area. However, it turned out that the use of photovoltaic systems can contribute to a higher reduction in pollutants emitted to the atmosphere as a result of the alternative combustion of fossil fuels. Additionally, the optimal angle of inclination of devices for solar radiation conversion located near Poznan was determined.

Risk Factors and Causes of Fever after Endoscopic Submucosal Dissection

Background To investigate the fever and related risk factors of gastrointestinal mucosa or submucosal lesions after endoscopic mucosal dissection(ESD).Method A retrospective analysis of patients undergoing ESD. Patients were divided into two groups according to the presence or absence of post-ESD fever. Patient-related factors and lesion-related factors were counted in both groups.Results The incidence of fever was 31.0% in 290 patients after the operation, 87 patients developed fever within 24 hours after operation. The average of (2.82 ± 1.186) days. According to logistic analysis, the surgical site was in the esophagus (OR value: 6.439; 95% CI: 2.030-20.424; P value: 0.002), with diabetes history (OR value: 3.289; 95% CI: 1.015-10.662; P value: 0.047), age≥70.6 years (OR value: 0.844; 95% CI: 0.805-0.884; P value: 0.000), resection diameter> 4.25 mm (OR value: 2.361; 95% CI: 5.202-29.371; P value: 0.000), operation time> 196min (OR value: 1.022; 95% CI: 1.003-1.042; P value: 0.022) were risk factors for fever.Conclusions Older patient, the operation site in esophagus, diabetes, large tumors and long operation time were more likely to develop post-ESD fever, The possibility of bacteremia after ESD is small, antibiotics do not need to be applied in advance.

Online survey among maritime pilots: job-related stress and strain and the effects on their work ability

Background Maritime pilots often navigate ships through challenging waterways. The required 24 h standby rotation system (ROS) poses a stressful working situation. This study aims to describe the current job-related stress and strain among maritime pilots and the effects on their work ability, taking into account the different rotation systems. Methods Within a cross-sectional survey, pilots of all German pilots’ associations were asked to complete an online questionnaire. The 1-week ROS (port pilots) was compared with the 4-month ROS (sea and canal pilots). The pilots’ subjective perception of stress and strain was assessed using an established ship-specific questionnaire. Daily sleepiness and work ability were examined respectively using the Epworth Sleepiness Scale (ESS) and the Work Ability Index (WAI). Results The study group consisted of 401 male German pilots with an average age of 48.5 years (participation rate 46.9%). More than 50% of the pilots evaluated irregular working hours as the main stressor in their job. 79.8% of the pilots (especially 4-month ROS) experienced high psychological demands in their workplace. 83.3% stated having regularly neglected their private obligations due to job assignments. Pilots from the 4-month ROS experienced insufficiently predictable free time and long operation times at a stretch as stressors (p < 0.001 and p = 0.037). Elevated daily sleepiness was found in 41.9% of the pilots. The overall evaluation of the WAI questionnaire showed good to very good work ability at 77.3%. Additionally, no significant differences in the daily sleepiness or the work ability were observed between the pilots of the different two ROS. Conclusions Due to their subjectively higher job-related mental demands, their disturbed work-life balance, and their long operation times at a stretch, it is likely that pilots from the 4-month ROS have significantly higher job stress compared to those in the 1-week ROS. However, this does not lead to more sleepiness or reduced work ability, which suggests that the pilots of this ROS are highly adapted to their working situation. Nevertheless, intervention measures with shortened ROS amongst sea and canal pilots’ associations should be tested in respect of benefit, practicability and acceptance by the pilots.

Hull Condition Monitoring and Lifetime Estimation by the Combination of On-Board Sensing and Digital Twin Technology

The industries using floating facilities such as FPSO and offshore wind turbine are increasing. Since these vessels have been fixed and operated in the installed area for a long period of time, they cannot be regularly docked, inspected and repaired as opposed to normal ship case, and limited to the inspection of the hull outer plates from under the water and the inspection of inside the tanks are conducted once every five years. These inspections involving visual inspections and thickness measurements at representative points, only examine the current state, and don’t evaluate quantitatively the future potential (remaining life) over the subsequent long operation period. To predict residual life in order to maintain the integrity of these structures, digital twin technology is proposed to realize this demand. This paper shows the method to develop digital twin assessment which solve the insufficiency of conventional monitoring and simulation method in order to utilize for risk-based inspection (RBI) and condition-based maintenance (CBM) to the operators.

INVESTIGATION OF RESIDUAL RESOURCE OF SPECIAL RAILWAY VAGON

The article examines the residual life of load-bearing metal structures (NMC) of special cars for the transportation of special contingent on the basis of the results of technical diagnostics and standard tests. Most scientific publications investigate the increase in the service life of different types of passenger cars by improving their design properties. The following methods are used in the study: resetting from wedges, resource tests for impact strength, impact tests, static strength tests. On the basis of carrying out technical diagnostics and standard tests the possibility of establishment of new appointed service life of cars is defined. The residual resource was set at one of the minimum calculated values obtained by mathematical dependence to calculate the residual service life. When determining the residual resource during the standard tests, the evaluation of the fatigue resistance margin was performed taking into account the stress of the load-bearing structures of the car during the tests. It is concluded that the condition of load-bearing metal structures of special wagons for transportation of special contingent after long operation does not approach the limit. The obtained practical and theoretical results make it possible to extend the service life of special wagons for the transportation of special contingent beyond the established by the manufacturer.

ASSESSMENT CARTS STRENGTH INDICATORS WAGONS WITH EXPIRED SERVICE LIFE

Currently, a significant number of units of specialized cars of 1520 mm gauge in Ukraine has a service life that exceeds that assigned by the manufacturer. At the same time, many years of experience in diagnosing and analyzing the operation of carts of these cars by specialized organizations, shows that their technical condition after long operation shows that the specified service life specified in the technical conditions in most cases far from the limit. This is largely due to the significant margin of safety, which is laid down in the design, and the peculiarities of the operation of a particular type of car. The paper considers the issues of assessing the operation of such cars on the example of the carriage of the weighing car, bogie model 18-102, and the carriage of the passenger car model KVZ-TsNII used in the track economy for transportation of workers. The average daily mileage of such cars is 60-70 percent less than the average mileage that is laid down when calculating the service life assigned by the manufacturer. The evaluation and methods of determining the strength of the frames of carriages of special cars are performed. Conclusions are made based on the results of the analysis of the strength of the carriages of special cars.

TESTS OF LOADING STRUCTURES OF A SPECIAL ROLLING STOCK AFTER LONG OPERATION

Traffic safety is an essential requirement for railways. In order to ensure uninterrupted transportation of passengers and goods by rail by the enterprise of JSC "Ukrainian Railways", the task of ensuring the operation of rolling stock outside the assigned line of service remains urgent. Proceeding from this, it follows that it is necessary to carry out tests aimed at creating conditions for the operation of rolling stock while maintaining dynamic and strength characteristics. This article presents the order, scope and results of strength tests of rolling stock after long-term operation on the example of an AS1a-type railroad car. The results of the maximum stress levels, standard deviation, fatigue safety factors, the dependence of the stress level on the speed of movement are obtained. Based on the research results, a technical solution has been developed that allows using technical diagnostics methods to extend the service life of the AS1a type railroad cars after the end of the assigned service life.