Tomasz Nowakowski

Reliability Model of Combined Transportation System

Combined transportation system reliability model is presented. The model contains 5 operation and maintenance states. The model is built using phased-mission model that describes the changes of transportation means. Reliability of CT as analysed using Markov theory. Some examples of the model sensitivity on the rate of rail phase are shown.

Exact and approximation methods for dependability assessment of tram systems with time window

The transportation system examined in this paper is the city tram one, where failed trams are replaced by reliable spare ones. If failed tram is repaired and delivered, then it comes back on work. There is the time window that failed tram has to be either replaced (exchanged) by spare or by repaired and delivered within. Time window is therefore paramount to user perception of transport system unreliability. Time between two subsequent failures, exchange time, and repair together with delivery time, respectively, are described by random variables A, E, and D. A/E/D is selected as the notation for these random variables. There is a finite number of spare trams. Delivery time does not depend on the number of repair facilities. Hence, repair and delivery process can be treated as one with infinite number of facilities. Undesirable event called hazard is the event: neither the replacement nor the delivery has been completed in the time window. The goal of the paper is to find the following relationships: hazard probability of the tram system and mean hazard time as functions of number of spare trams. For systems with exponential time between failures, Weibull exchange and exponential delivery (so M/W/M in the proposed notation) two accurate solutions have been found. For systems with Weibull time between failures with shape in the range from 0.9 to 1.1, Weibull exchange and exponential delivery (i.e. W/W/M) a method yielding small errors has been provided. For the most general and difficult case in which all the random variables conform to Weibull distribution (W/W/W) a method returning moderate errors has been given.

Maintenance Decision Making Process – A Case Study of Passenger Transportation Company

In the presented paper, the authors’ research work is focused on the analysis of maintenance decision making process performance with taking into account necessary operational data availability. Thus, in the Introduction section, the transportation systems maintenance issues are described. Later, there is a comprehensive literature overview in the analysed research area provided. This gives the possibility to present the decision making process in the transportation systems’ maintenance management area. Later, in the next Section, the case study for maintenance management processes performance in chosen passenger transportation company is investigated. Following this, the computer systems used for operational data gathering are characterised, and the data availability is investigated.

Reliability Assessment of Production Process – Markov Modelling Approach

In the presented paper, authors focus on the issues connected with production processes reliability assessment. Such analyses regard considering many different factors and requirements. Thus, based on the developed multidimensional definition of production process reliability, the seven-state Markov model of production process performance is presented. Later, there is provided a comprehensive sensitivity analysis of the developed model based on the expert opinions in the area of model parameters estimation. The work ends up with summary and directions for further research.

ISO 55001 and difficulties of its implementation in polish enterprises

Abstract In the presented paper, authors focus on the issues related to asset management in enterprises. The aim of the article is to present the requirements and standards defined in ISO 55001. Thus, there are presented the basic definitions related to the research area. Later, there are discussed the main guidelines set out in the standard, with taking into consideration e.g. asset management system structure. Moreover, there are defined the basic procedural steps in the process of ISO 55001 standard implementation in enterprises. This gives the possibility for the analysis of ISO 55001 standard possibilities of implementation in Polish enterprises. The article concludes with a summary.

The efficiency of tram articulations compared to vibroacoustic emissions

Human quality of life is constantly increasing, and so does the comfort of travel by various means of public transport, especially rail transport. One of the more crucial criteria for assessment of travel comfort is vibroacoustic comfort. This aspect is also substantial among rail vehicle operators and manufacturers. Sound quality evaluation is related to psychoacoustic indicators, but reducing the levels of acoustic pressure does not always correlate to increased quality of the perceived sound and improvement of human sound perception. Moreover the cause of unpleasant noise has to be taken into consideration. In many examples it is induced by specific vibrations and/or friction forces through components. The following article presents experimental research carried out in the in-situ conditions, testing the quality of work carried out by tram articulations considering vibroacoustic emissions. Several measurements were taken of vibroacoustic signals in several urban rail vehicles of the same type. Two different trams were chosen for analysis and their vibroacoustic emission levels as well as sound quality parameters were compared. One of the more crucial aspects of the research was to determine the dependency between vibrations around the area of articulations and squealing noise. The results indicate a large correlation between signals and deterioration in the work quality of the articulation in the given tram. Moreover, the authors suggest expanding on currently carried out maintenance in order to minimise inconvenient vibroacoustic phenomena

From Reliability to Resilience: Modern Challenges of Safety and Reliability Theory and Applications / Od Nieuszkadzalności Do Odporności: Współczesne Wyzwania Teorii i Inżynierii Niezawodności i Bezpieczeństwa

Abstract There are several trends of development of modern reliability theory; some of them are subjects of everyday engineering activity, like: quality control of mass production or “pure” reliability. But most of these issues, such as: effectiveness, survivability, safety, security, are currently the subject of many works of conceptual, modeling, case study or survey nature. The aim of this article is show how the performance requirements of technical objects were supplemented with: customer expectations (quality), abilities to prevent the loss of the object properties in operation time (reliability and maintainability), the effects of undesirable events and protection against them (safety and security) and the ability to restore performance (resilience). Streszczenie Można wyróżnić główne kierunki rozwoju współczesnej teorii niezawodności; niektóre z nich są przedmiotem codziennych działań inżynierskich, jak np.: kontrola jakości w produkcji masowej czy „czysta” analiza niezawodności. Ale większość tych wyzwań, takich jak: efektywność, odporność czy bezpieczeństwo są obecnie przedmiotem wielu prac koncepcyjnych, modelowania i badań. Celem artykułu jest pokazanie jak wymagania w stosunku do osiągów obiektu technicznego były poszerzane o: oczekiwania klienta (jakość), zdolność do zapobiegania utracie właściwości przez obiekt podczas eksploatacji (nieuszkadzalność i obsługiwalność), skutki niepożądanych zdarzeń i ochrona przed nimi (bezpieczeństwo) oraz zdolność do odtworzenia osiągów (odporność na zagrożenia).

Problems of Logistic Systems Vulnerability and Resilience Assessment

The aim of this chapter is to present and investigate the main concepts of supply chain vulnerability and resilience. Thus, the fundamental differences between vulnerability and resilience definitions are discussed. General aspects of supply chain vulnerability understanding are presented and some problems with vulnerability assessment are underlined. The main issues on vulnerability and resilience assessment are discussed, and the case study of production system resilience estimation is investigated.

Uncertainty Problem in Decision Support System for Means of Transport Maintenance Processes Performance Development / Problem Niepewności W Systemie Wsparcia Decyzyjnego Procesów Utrzymania W Stanie Zdatności Środków Transportu

Abstract In this paper, the authors’ research work is focused on uncertainty analysis implementation in the developed DSS for transportation means’ maintenance processes performance. Thus, in the Introduction section, the transportation means’ maintenance processes issues and the uncertainty problem are described. Later, there is briefly literature overview in the research area discussed. In the next Section, the expert system for means of transport maintenance processes performance is also investigated. Following this, the uncertainty analysis is developed and the examples of expert system implementation are given. The work ends up with summary and directions for further research. Streszczenie W artykule autorzy skupili się na analizie niepewności danych w opracowanym systemie wsparcia decyzyjnego procesów utrzymania w stanie zdatności środków transportu. We wprowadzeniu problem niepewności oraz zagadnienia utrzymania w stanie zdatności środków transportu zostały omówione. Następnie, przedstawiono krótki przegląd literatury z badanego obszaru. W kolejnym kroku, przedstawiono system ekspertowy wspierający proces decyzyjny w badanym obszarze. Pozwoliło to na opracowanie analizy niepewności oraz jej implementację w systemie ekspertowym. Pracę kończy podsumowanie i wskazanie kierunków dalszych prac badawczych.