We consider the problem of optimizing rolling stock operations, including preventive maintenance, to enhance technical availability. Our approach accounts for various types of rolling stock and their multi-level maintenance schedules, integrating both time-based and distance-based cycles, a combination seldom explored in existing literature. Given the complexity of this problem, we focus on short-term planning, as it provides decision makers with implications for practice regarding current operational challenges and may also influence strategic decisions. We propose a branch and bound approach to derive optimal solutions for rolling stock operations, addressing limitations in traditional manual planning commonly used in business practice. Additionally, we developed an efficient heuristic to find a satisfactory solution in a short time. Simulations for real data show that our algorithms can provide feasible rolling stock schedules that significantly improve fleet availability in the enterprise. This improvement not only reduces maintenance and downtime costs but also enables the fulfillment of more transport orders, aligning with business priorities.
The paper presents reliability and availability analysis of the transport system, taking into account its structure, that is composed of dependent subsystems. The issues introduced are basing on the assumption that one subsystem impacts on functioning of other subsystems, meaning - disruptions occurring within the subsystem can reduce functionality and change level of safety and inoperability of others. By means of multistate approach to analysis, it has been assumed that the deterioration of one subsystem affects the reliability of other subsystems and the entire system. Following this assumption, the transport system reliability function and its basic reliability characteristics were determined. In addition, the system availability function was set out, assuming that its renewal is carried out when its reliability falls below a certain threshold. Furthermore, the reliability and availability analysis of the transport system were conducted, taking into account additional stress on its particular subsystem at certain time points. The summary contains conclusions resulting from the analysis and comparison for various additional stress levels.
The paper discusses the reliability analyses of the groups of objects of the modular design. Such objects are common in the designing and operation of machines. The modular design can provide significant benefits in the area of reliability, hence further research in this area is justified. The aim of the work is to determine the effect of preventive maintenance on the reliability and availability of the selected groups of objects of the modular design. The research considered cases when the operating time to failure of the individual modules (subassemblies) of a machine is described by different probability distributions, and the selected unit is preventively renewed. A positive effect of preventive maintenance on reliability indexes was demonstrated. The results of the conducted analyses may constitute a guideline for designing groups of machines.
PL
W artykule omówiono przeprowadzone analizy niezawodności grup obiektów o konstrukcji segmentowej. Obiekty takie występują powszechnie w budowie i eksploatacji maszyn. Konstrukcja segmentowa może zapewniać istotne korzyści w obszarze niezawodności, stąd zasadne są dalsze badania w tym zakresie. Celem pracy jest określenie wpływu odnawiania prewencyjnego na niezawodność i gotowość wybranych grup obiektów o konstrukcji segmentowej. W ramach badań rozpatrzono przypadki, gdy czas eksploatacji do uszkodzenia poszczególnych segmentów (podzespołów) maszyny jest opisywany różnymi rozkładami prawdopodobieństwa, a wybrana jednostka jest odnawiana profilaktycznie. Wykazano pozytywny wpływ odnawiania prewencyjnego na wskaźniki niezawodności. Wyniki przeprowadzonych analiz mogą być wskazówką w projektowaniu grup maszyn.
Bloki węglowe będą towarzyszyć transformacji polskiej energetyki przynajmniej do czasu, gdy stabilizowanie systemu energetycznego przejmą niżej emisyjne, sterowalne źródła energii oraz jej wielkoskalowe magazyny. Zanim to nastąpi przyrost generacji z pogodozależnych źródeł OZE będzie skracał ich czas pracy, zwiększał liczbę i czas nieplanowanych postojów oraz zwiększał liczbę uruchomień. Podczas gdy efekt ekonomiczny ich eksploatacji może być coraz mniejszy, dyspozycyjność pozostanie ich najbardziej pożądaną cechą.
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Coal fired power units will accompany the transformation of the Polish energy sector at least until the stabilization of the energy system is taken over by lower emission controllable energy sources and its large-scale storage. Before this happens, the increase in generation from weather-dependent RES sources will shorten their operating time, increase the number and duration of unplanned outages and increase the number of starts. While the economic effect of their operation may be decreasing, availability will remain their most desirable feature.
The South Field Mine, situated in Western Macedonia, Greece, has used continuous surface mining systems: bucket wheel excavators (BWEs), belt conveyors, and stackers for over four decades of uninterrupted operation. This paper, using the principles of the Lessons-Learned process, tries to identify, document, analyse, and disseminate valuable knowledge and experience acquired in this mine, focusing on the performance indicators and downtimes of BWEs. Quantitative analysis methods were employed to analyse data and detect trends and factors for productive time losses. During a rather crucial period for the mine, due to decarbonisation and energy transition policies, the performance of BWEs exhibited a decline. On the other hand, availability and utilisation remained relatively stable. Mechanical failures and annual maintenance appeared to be the primary causes of downtimes. Non-operating time, connected with the lack of personnel, also had a great impact on operational efficiency. According to the linear regression model, this downtime has the greatest influence on the availability of the BWEs. In conclusion, this research implies the importance of the incorporation of new technologies for monitoring and producing daily and monthly records of the mine activities, which can enhance the overall effectiveness of a continuous mining system.
Overall equipment effectiveness (OEE) is a key indicator to measure the effectiveness of production systems. This paper aims to evaluate and improve a plastic production line based on OEE evaluation. An integrated framework is proposed to enhance the production system efficiency. This paper presents the data for a Plastic production line in Jordan under real working conditions. The data covers three months. A framework process to improve the OEE of the Plastic production system was proposed. Six major stoppage losses were inspected with the help of Pareto analysis. Furthermore, the actual availability, efficiency, and quality rate measures, together with the whole OEE for each working day, week, and month of the production line were shown. The methodology is based on determining the OEE of a Plastic production line after determining the causes of failures. The fishbone diagram tool is used to determine the root causes of failures. To improve the OEE measure, several losses are identified. The results reveal that the company should improve its policy to improve the production line’s performance and reduce losses. Top management should also pay attention to reducing the speed losses, which consist of 58.1%, and eliminate the planned and unscheduled disruptions covering 12.73% of all losses. This can be achieved by establishing a proper operation management procedure and strategy. This, in turn, optimized the equipment’s effectiveness. The quality procedure should include the changeover program that may be executed every day. Similarly, all preventive maintenance procedures for the six machines should be properly executed in predetermined intervals. There are several limitations in the research. Firstly, the research case study is only the plastic production system. Secondly, the research is related to the downtime or stoppage by analyzing it using fishbone diagram. Further, supported by other techniques such as the Pareto chart, six big losses analyses and CED. This research conducted on a Plastic industry. However, similar studies can be carried out in future in other manufacturing industries like electronic, pharmaceutical, textile industries, etc., and service industry. However, as future research work the contributions of this paper with other lean manufacturing concept like six sigma, quality function deployment, TQM, and just-in-time manu-facturing, can also be conducting to assess the overall production line efficiency. On the other hand, several statistical tests can be implemented based on data collected of TPM performance indicators. The proposed method supports policymakers in their decision-making process on the operations management line. Further-more, it improves the production systems’ productivity quality, and performance, reducing unplanned stop-pages and breakdowns, and reducing maintenance costs.
The paper concerns the quantitative assessment of the availability of the groups of machines of the two different types of construct /design/ – traditional and modular, which perform the same functions and in the analyzed groups constitute koon-type reliability structures. The main aim is to determine the size of the differences in the availability and reliability of such groups of machines at different values of the characteristics regarding the failure rate and renewal of their subassemblies and modules. The solution to the problem was obtained through digital simulation, for which the model and assumptions were developed by the authors. The obtained results indicate that the groups of the machines of modular construct /design/ are characterized by better reliability and availability, which may constitute one of the guidelines in the process of making investment decisions and planning the use and maintenance of this type of machines.
PL
Artykuł dotyczy ilościowej oceny gotowości grup maszyn o dwóch różnych typach konstrukcji: tradycyjnej i segmentowej, które pełnią te same funkcje i w analizowanych grupach tworzą struktury niezawodnościowe typu kzn. Głównym celem jest określenie, jak duże są różnice w gotowości i niezawodności takich grup maszyn przy różnych wartościach charakterystyk dotyczących awaryjności i odnowy ich podzespołów i segmentów. Rozwiązanie problemu uzyskano na drodze symulacji cyfrowej, do której model i założenia opracowali autorzy. Uzyskane wyniki wskazują, że lepszą niezawodnością oraz gotowością charakteryzują się grupy maszyn o konstrukcji segmentowej, co może stanowić jedną ze wskazówek w procesie podejmowania decyzji inwestycyjnych i planowania eksploatacji tego typu maszyn.
Traditional availability, reliability, and safety models face the dimension problem due to a huge number of components in modern systems, motivating further research in this field. This paper focuses on multi-fragmental and multiphase models for availability and functional safety assessment of the information and control (I&C) systems with two-cascade redundancy considering design faults manifestation during operation. The methodology of the research is based on Markov and semi-Markov chains with the utilization of multi-phase modeling. Several multi-phase models are developed and investigated considering different conditions of operation and failures caused by version faults. The case study of the research is based on the analysis of safety-critical nuclear power plant I&C systems such as the reactor trip systems developed using the programmable platform RadICS.
The purpose of the article was to analyse the reliability, maintainability, and availability estimates of firefighting and rescue engines. Analysing the reliability parameters of heavy firefighting and rescue vehicles over time requires knowledge of their failures. In this article, failure data from the six years of maintenance of ten heavy firefighting and rescue vehicles from ten were analysed in relation to two main subsystems. Reliability analysis was performed and the best-fit distribution was found, with the parameters calculated. For both subsystems, the chassis combined with the cabin and the superstructure, the 2P-Weibull distributionwas identified as the most suitable fit. The availability and maintenance indicators for each vehicle and the individual subsystems were calculated. It was clearly defined that there exists a significant difference between the two subsystems analysed in terms of failure characteristics, as well as maintainability and availability parameters.
Fleet systems are considered complex due to the interaction between their units and components. Maintenance management systems face various challenges to achieve acceptable availability and reliability rates at a reasonable cost. A critical task for making maintenance decisions is understanding the system requirements to select maintenance policies appropriate for the actual and future system state. When there is a replacement shortage in a fleet system, and it is impossible to supply new spare parts quickly, cannibalization policies can mitigate this scarcity via the interchange of components. However, this procedure presents the maintenance manager with different evaluation effects, such as increased maintenance hours, decreased system reliability rate, and unavailability in some units. Finding an equilibrium between the benefits and risks has caught the attention of researchers. This work gathers diverse proposals for applying cannibalization policies and the effects that arise from using them. Models, methods, tools, and identified gaps in understanding what parameters of the components and environments of the fleet systems favor cannibalization are discussed.
The disruption of services must be kept at a minimum in telecommunications networks so that the consequences are not too severe and their durations are as short as possible. Maintenance policies often rely on the steady-state availabilities of each element of the system, and focus on the system’s weak links. The end-to-end (or two-terminal) availability – a standard performance index – of a meshed network has long been studied, but mainly for small systems, and assuming constant values for the availability of each element. When taken into account, the time-dependent contributions of links and nodes to the system unavailability were computed using exponential failure and repair distributions. In this work we revisit the meshed network first proposed by Walter, Esch, and Limbourg (ESREL 2008), and compute the end-to-end availability between two nodes, where the individual contributions of links and nodes are kept. This allows the ranking of links and nodes, using well-known performance indices (Birnbaum, Risk Reduction Worth, etc.). We can thus determine the elements that should receive due attention in maintenance and resilience studies. However, as the steady-state availability may not always be a lower bound to the transient availability in the case of non-exponential failure and repair distributions, we have studied the influence of such configurations on the time-dependent behaviours of all the aforementioned quantities. We then discuss the influence of uncertainty in the availability values, and compare the results obtained for the all-terminal reliability, another often-used performance criterion of networks.
The purpose of this article is to investigate the availability of vertical machining centre using a Markovian technique and Monte Carlo simulation (MSC). Availability is a critical performance metric for industrial systems. Conventional methodologies focus for steady-state availability evaluation of mechanical systems. The research analyses transient availability assessment for four different system configurations. Monte Carlo simulation modelling is used to compare the results and future scope is suggested to use the developed MCS based algorithms/codes for non-exponential (time dependant) failure and repair time distributions. The research also investigates the influence of active and passive redundancy on availability, indicating that for the vertical machining centre, parallel architecture with standby redundancy outperforms active load sharing. The chapter includes a sensitivity study that modifies the repair rates of the ball screw and sub-assembly to make the component selection process easier for engineers. The authors believe that this chapter will be useful to maintenance and practising engineers because it will assist them in making informed decisions about system availability, developing maintenance/replacement policies, and determining the repair level required to achieve the desired system availability.
The reduction of greenhouse gas emissions is a relevant challenge for a sustainable development. Waste heat could be used to produce hot water by using a recovery system. This article studies the availability of a combined heat and power systems (CHP) in extreme area (Antarctic) through the integration of a waste heat recovery system with a diesel generator to produce hot water. The reliability and availability principles are incorporated to explore how the profile of hot water consumption and the hot water storage tank size affect system availability. Different combined heat and power systems are thus classified, and their availability indexes modelled by adopting the continuous Markov approach and the state space model. The results indicate that the CHP systems availability is strongly influenced by the daily hot water demand profile. As a useful recommendation, one of the considerations for increasing availability, reducing costs and greenhouse gas emissions with the CHP system is to include a hot water tank in the analysis.
Many universities in Poland are based in historic buildings. As public facilities, they must have accessibility for people with disabilities. Therefore, historic buildings undergo regular reconstruction to ensure accessibility on the basis of technical and construction regulations and the Convention on the Rights of Persons with Disabilities. For the purpose of the study, those with exceptional architectural, cultural and historical are presented. The article is concerned with determining the current state of accessibility of selected Polish universities for students with mobility disabilities. The first part of the paper deals with the verification of the background material in the form of statistical data and support programmes for the studied group of users. The second part presents historical information about the historic buildings along with a qualitative analysis of the elements already applied to eliminate architectural barriers. Nine selected historical teaching facilities located both in Warsaw and scattered throughout the country were analysed using the field observation method. The conclusion presents the results indicating the application in the realizations of the principle of rational improvement stating that the preservation of historic value can become paramount to ensuring full accessibility. Still, monuments should be treated individually, and the same applies to disabilities, where each is different and requires individual perception and treatment.
New systems are produced and developed to meet specific needs, and their reliability is the most important issue. In the maritime industry, evaluating failures in a ship’s propulsion system results in high costs and the loss of prestige for the company. Land/sea fleet employees need to detect and minimize the failures that may occur in ship propulsion systems in advance to ensure the continuity of the ships’ operations. In this study, the recorded failure data of four different ships belonging to a fleet in the last 10 years are used. Failures were examined as a whole since the ships have similar propulsion systems. The obtained failure data were grouped, and the average time to fix the failures was determined by the chief engineer and made suitable for reliability, availability, and maintainability (RAM) analysis. A suitable model was created for grouped failures by Isograph’s RWB software. As a result of the analysis of the propulsion system and its subsystems, the main engine of the ship was shown to have the best reliability. Furthermore, the most important components were the cylinders of the main engine as subsystems. This study highlights the components that are important to the reliability of a propulsion system. Thanks to the RAM analysis, improvements can be pinpointed on a ship’s propulsion system, which will increase the operations of the maritime industry. Reducing failures will further increase the confidence in maritime transport and strengthen its place among the modes of transportation. This study provides a valuable resource for academicians, experts, as well as companies working on reliability, availability, and maintainability in the future.
W ostatniej dekadzie zabudowa mieszkaniowa w Krakowie rozwija się szczególnie intensywnie. Brak planów miejscowych w wielu częściach miasta powodował dotąd i nadal jeszcze nierzadko powoduje sytuację, w której tereny inwestycyjne są maksymalnie zabudowywane bez całościowej wizji dla obszaru na jakim się znajdują. Nierzadko wpływa to niekorzystnie na jakość przestrzeni publicznych, których charakterystyka staje się zaledwie wypadkową procesu zabudowy rozwijanej z niewielkim udziałem zieleni publicznej. Niniejszy artykuł prezentuje analizę przekształceń funkcjonalno-przestrzennych obszaru „Ludwinów-Mateczny” w Krakowie, zabudowywanego dotąd mimo braku planu miejscowego, atrakcyjnego nie tylko pod względem lokalizacyjnym, ale także ze względu na sąsiedztwo obszarów przyrodniczo cennych. Przedstawiono w nim wyniki badań procesu rozwoju lokalnego środowiska mieszkaniowego w okresie od ok. 2010 do 2022 roku. Badania oparto na analizach dostępnych dokumentów planistycznych, statystycznych, autorskiej analizie ilościowej zmian w strukturze przeznaczenia i użytkowania terenu, a także badaniach terenowych.
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In the last decade residential development in Krakow has been particularly intensive. In consequence of many parts of the city being left without any local zoning plan, land designated for property development is developed to the maximum while the overreaching vision for the area is missing. This often has an adverse effect on the quality of public spaces, the characteristics of which is merely resultant from the development process developed with little public green space. This article presents an analysis of the functional and spatial transformation of the “Ludwinów-Mateczny” area in Krakow, which has been developed so far in spite of the lack of a local zoning plan, attractive not only in terms of its location, but also because of its proximity to valuable natural areas. It presents the results of a study of the local housing development process over the period starting approximately in 2010 and ending in 2022. The research was based on analyses of available planning and statistical documents, the author’s quantitative analysis of changes in the land designation (purpose) and use structure, as well as on the field research.
W artykule przedstawiono jak należy rozumieć tajemnicę przedsiębiorstwa i jakie korzyści płyną z jej wdrożenia. Jakie wymogi musi spełniać informacja żeby mogła być chroniona tajemnicą przedsiębiorstwa. Zdefiniowano również główne obszary, które musi wziąć pod uwagę przedsiębiorca decydując się na rozwiązania związane z bezpieczeństwem informacji. Jak istotny jest człowiek w procesie oraz monitoring wdrożonych rozwiązań prawnych, organizacyjnych i technicznych. Przedstawiono również kierunki prawidłowego zarządzania informacjami szczególnie ważnymi dla organizacji. Wskazano obszary monitoringu wdrożonych rozwiązań takich jak audyt, klasyfikacja informacji czy analiza ryzyka. W artykule przedstawiono również obszary które warto objąć wewnętrznymi regulacjami tajemnicy przedsiębiorstwa. Przeanalizowano co przede wszystkim stanowi o bezpieczeństwie aktywów w przedsiębiorstwie. Zwrócono również uwagę na konieczność odpowiedniego zarządzania informacjami stanowiącymi tajemnicę przedsiębiorstwa i co to oznacza w praktyce funkcjonowania organizacji. Jak ogromne znaczenie ma ciągły monitoring zastosowanych środków bezpieczeństwa poprzez cykliczne audyty i analizę ryzyka.
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The article presents how to understand a trade secret and what are the benefits of its implementation. The main areas that an entrepreneur must take into account when deciding on solutions related to information security have also been defined. How important is the human being in the process and monitoring of implemented legal, organizational and technical solutions. What requirements must the information meet in order to be protected by a trade secret. The directions for proper information management of particular importance to the organization were also presented. The areas of monitoring the implemented solutions, such as audit, information classification or risk analysis, were indicated. The article also presents the areas that should be covered by internal regulations of trade secrets. It was analyzed what primarily determines the security of assets in the enterprise. Attention was also drawn to the need of proper management of information constituting a trade secret, as it has a crucial meaning in the practical functioning of the organization.
Local Area Network as a computer network on small scale. The limited distance between a room, building, or office. The factor of LAN is performance, where the performance can do by using availability, reliability, response time, and throughput. Its function of it is to know the performance of LAN. Availability, use to measure the time of the network. It’s working at all work of the network it is called MTBF and MTTR. Reliability, use to measure the time of the network, which is work to transmit the data and avoid data from errors. Response time, use to measure the time that needs by the data to begin from the computer transmission. The process does in host and time. It’s needed to give back the data to the sender. Throughput, use to measure the total data that it’s transmitted at a certain time.
PL
Sieć lokalna jako sieć komputerowa na małą skalę. Ograniczona odległość między pokojem, budynkiem lub biurem. Czynnikiem sieci LAN jest wydajność, gdzie wydajność może być realizowana przy wykorzystaniu dostępności, niezawodności, czasu odpowiedzi i przepustowości. Jego funkcją jest poznanie wydajności sieci LAN. Dostępność, użyj do pomiaru czasu sieci. Działa przy wszystkich pracach sieci o nazwie MTBF i MTTR. Niezawodność, służy do mierzenia czasu sieci, czyli pracy nad przesyłaniem danych i unikaniem błędów danych. Czas odpowiedzi służy do pomiaru czasu potrzebnego na rozpoczęcie transmisji danych przez komputer. Proces odbywa się w gospodarzu i czasie. Jest potrzebny do oddania danych nadawcy. Przepustowość służy do pomiaru całkowitej ilości danych przesyłanych w określonym czasie.
Responding to the needs of quality and robustness of analysis and management of degradation of equipment, to increase their life cycle and to expand these facilities to become more and more sophisticated and agronomic. This work proposes a contribution to increase the survival of a gas turbine, installed in a gascompression plant, with a comparative study between the two-parameter Weibull distribution. A new modified Weibull distribution was proposed also to reduce the risk of occurrence of failure in this rotating machine. A Statistical analysis and validation on the synthesis of turbine's reliability data and failures were considered, with a particular focus on the use of this data to increase the availability of this type of machine. So, developing a maintenance plan based on their reliability indices for scheduled inspections.
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