Технологія обслуговування контактної мережі за станом з марковською апроксимацією зносу контактних проводів

The technologies of OCL condition based maintenance were improved for providing reliable and economic current collecting on electrified railways and in traction power networks of urban electric transport. It is established that one of the most perspective methods of reducing operating costs is the transition to scientifically justified terms of repair and planning of works based on the actual state of OCL, the reliability of which is determined by the reliability, repair suitability and durability of the elements. The basic criteria of the current collecting process are proposed: the value of contacting pair wear, the detachment of the current collectors from the wires, the scope of oscillations of pantograph head and the contact pressure, coefficients of contact unreliability and cost savings of collecting a power from catenary, and, finally, a minimum of annual operating costs. Technology of maintenance according to Markov type parameter control is developed. Models of controlling actions on stagger and the contact wire gradient adjustment processes are developed. The standard linear programming algorithm was used to solve the problem. The application of such technology to determine the matrix of controlling actions based on the results of monitoring the stagger and the contact wire gradient is shown. The factors that determine the cost of staying in a state of stagger have been identified. The controlling actions matrices on the stagger and the contact wire gradient and the cost of staying in these gradient states are established. The technology of service with Markov approximation of wear of contact wires is offered. It has been investigated that the contact wires, primarily due to wear, are degraded during operation. Degradation processes cause gradual failures. The first group of failures: breakages, burnouts, local wear - require controlling actions to incut the insertion or putting into operation a shunt. The second group: a burnout, a decrease in the average cross-section of a wire less than the allowable one requires controlling actions to replace the wire of the entire tension length. After conducting the first type of controlling actions, the contact wire returns to the working state with the previous value of the determining parameter. When performing a second type of controlling actions, the defining parameter returns to its original state. If the quantification step is chosen such that the intensities of failures and transitions from one state to another with a sufficient degree of accuracy were constant, then the graph of states and transitions, as well as the Kolmogorov differential equations, can be used for the research. The readiness function, the density of time distribution of infallible operation, the total failure rate, and the average recovery rate from state  to  are determined. Thus, all reliability indicators are defined and it is possible to use them in determining the condition of the contact wire of the tension length. Experience has shown that the most effective diagnostics of the condition of OCL devices combines the assessment of the state on mathematical, simulation models and measurements with the use of car laboratories for testing the contact network and devices for monitoring the parameters of the contact wire for the railcar.Удосконалено технології обслуговування контактної ме-режі за станом для забезпечення надійного і економічного струмозняття на електрифікованих залізницях і в елект-ротягових мережах міського електротранспорту. Встано-влено, що одним з найбільш перспективних методів зни-ження експлуатаційних витрат є перехід до науково-обґрунтованих термінів ремонту і планування робіт на основі фактичного стану КМ, надійність якої визначаєть-ся безвідмовністю, ремонтопридатністю і довговічністю елемен6тів. Запропоновані основні критерії процесу струмозняття: величини зносу контактної пари, відриви струмоприймачів від проводів, розмах коливань полоза і контактного натиснення, коефіцієнти ненадійності робо-ти контакту і економічності струмозняття, а також міні-мум річних експлуатаційних витрат. Розроблено технологію обслуговування за станом з контролем параметра марковського типу. Розроблені моделі керуючих дій процесів регулювання зиґзаґів і ухилу контактного проводу. Для вирішення задачі вико-ристано стандартний алгоритм лінійного програмуван-ня. Показано застосування такої технології для визна-чення матриці керуючих дій за результатами контролю зиґзаґа і ухилу (може нахилу?) контактних проводів. Встановлені фактори, що визначають вартості перебу-вання в станах зиґзаґів. Визначені матриці керуючих дій по зиґзаґам і ухилам контактного проводу і вартості пе-ребування в цих станах ухилів. Запропоновано технологію обслуговування з марков-ською апроксимацією зносу контактних проводів. Дослі-джено, що в процесі експлуатації контактні проводи де-градують, і в першу чергу за рахунок зносу. Деградаційні процеси викликають поступові відмови. Перша група відмов: обриви, перепали, місцевий знос – вимагають керуючих дій по врізанню вставки або установці шунта. Друга група: перепал, зменшення середнього перетину менше допустимого вимагають керуючих дій по заміні проводу всієї анкерної ділянки. Після проведення керу-ючих дій першого типу контактний провід повертається в працездатний стан з попереднім значенням визначаль-ного параметра. При проведенні керуючих дій другого типу визначальний параметр повертається в початковий стан. Якщо крок квантування вибрати таким, щоб інтенсивності відмов і переходів з одного стану в інше з достатнім ступенем точності були постійними, то для дослідження можна скористатися графом станів і перехо-дів, а також диференціальними рівняннями Колмогоро-ва. Визначена функція готовності, густина розподілу часу безвідмовної роботи, повна інтенсивність відмов та сере-дня інтенсивність відновлення із стану в . Та-ким чином, всі показники надійності визначені і є мож-ливість їх використання при визначені стану контактно-го проводу анкерної ділянки. Досвід показує, що найбільш ефективна діагностика стану пристроїв контактної мережі поєднує оцінку стану пристроїв на математичних, імітаційних моделях та ви-мірювань з використанням вагон-лабораторій випробу-вань контактної мережі та пристроїв стеження за пара-метрами контактного проводу для автомотрис

SARS-CoV-2 Production, Purification Methods and UV Inactivation for Proteomics and Structural Studies

Severe acute respiratory syndrome coronavirus-2 is the causative agent of COVID-19. During the pandemic of 2019–2022, at least 500 million have been infected and over 6.3 million people have died from COVID-19. The virus is pleomorphic, and due to its pathogenicity is often handled in very restrictive biosafety containments laboratories. We developed two effective and rapid purification methods followed by UV inactivation that allow easy downstream handling of the virus. We monitored the purification through titering, sequencing, mass spectrometry and electron cryogenic microscopy. Although pelleting through a sucrose cushion, followed by gentle resuspension overnight gave the best particle recovery, infectivity decreased, and the purity was significantly worse than if using the size exclusion resin Capto Core. Capto Core can be used in batch mode, and was seven times faster than the pelleting method, obviating the need for ultracentrifugation in the containment laboratory, but resulting in a dilute virus. UV inactivation was readily optimized to allow handling of the inactivated samples under standard operating conditions. When containment laboratory space is limited, we recommend the use of Capto Core for purification and UV for inactivation as a simple, rapid workflow prior, for instance, to electron cryogenic microscopy or cell activation experiments

Prevalence of Listeria species in camel sausages from retail markets in Aydin province in Turkey and RAPD analysis of Listeria monocytogenes isolates

Samples were taken from 100 camel sausages from the different retail markets in Aydin province in the south-west of Turkey and they were tested for the presence of Listeria spp by biochemical methods. Samples were enriched using Listeria Enrichment Broth and they were inoculated onto Listeria Selective Agar. Listeria monocytogenes was isolated from nine samples (9%), Listeria innocua from 14 samples (14%) and Listeria welshimeri from two samples(2%). A 701 bp fragment of listeriolysin O sequence for L. monocytogenes was amplified using specific primers by polymerase chain reaction (PCR) for confirmation of the identification. A random primer (OPA-11) was used in a random amplified polymorphic DNA (RAPD) assay. This detected five different band profiles amongst the L. monocytogenes isolates, indicating a relatively large amount of genetic heterogeneity amongst the nine isolates. The study has highlighted the need for improved strategies for food safety, in particular appropriate hygienic precautions to avoid contamination of sausage during the manufacturing process and appropriate preservation techniques during storage and transport, to prevent transmission of Listeria spp to consumers at home and abroad

One-year molecular survey of astrovirus infection in turkeys in Poland

The presence of turkey astrovirus (TAstV) was monitored in meat-type turkey flocks in Poland in 2008. Clinical samples (10 individual faecal swabs/flock) from 77 flocks aged 1-19 weeks were collected from different regions of the country. RT-PCR experiments were performed for detection and molecular characterization of TAstV using four sets of primers within the RdRp gene (ORF1b). The prevalence of astrovirus was 34/77 (44.15%) in the flocks tested. TAstV type 2 was associated with 30 of 77 infections (38.9%), either alone or in mixed infections; TAstV type 1 was detected in 9 of 77 flocks (11.6%), either alone or in mixed infections; ANV was detected only in one flock (1.29%) by sequence analysis during this study. Phylogenetic analysis revealed genetic variability in the TAstV strains that were isolated. Some of Polish TAstV-2 strains were genetically related to the North American isolates; however, most of them formed a distinct subgroup of “European” isolates, suggesting their separate origin or evolution. Additionally, due to the high variability of the TAstV sequences, the most suitable method for TAstV typing seems to be sequencing

Self-Association of Organic Solutes in Solution: A NEXAFS Study of Aqueous Imidazole

N K-edge near-edge X-ray absorption fine-structure (NEXAFS) spectra of imidazole in concentrated aqueous solutions have been acquired. The NEXAFS spectra of the solution species differ significantly from those of imidazole monomers in the gas phase and in the solid state of imidazole, demonstrating the strong sensitivity of NEXAFS to the local chemical and structural environment. In a concentration range from 0.5 to 8.2 mol L−1 the NEXAFS spectrum of aqueous imidazole does not change strongly, confirming previous suggestions that imidazole self-associates are already present at concentrations more dilute than the range investigated here. We show that various types of electronic structure calculations (Gaussian, StoBe, CASTEP) provide a consistent and complete interpretation of all features in the gas phase and solid state spectra based on ground state electronic structure. This suggests that such computational modelling of experimental NEXAFS will permit an incisive analysis of the molecular interactions of organic solutes in solutions. It is confirmed that microhydrated clusters with a single imidazole molecule are poor models of imidazole in aqueous solution. Our analysis indicates that models including both a hydrogen-bonded network of hydrate molecules, and imidazole–imidazole interactions, are necessary to explain the electronic structure evident in the NEXAFS spectra