Kostogryzov Andrey, Nistratov George, Nistratov Andrey
Applicable technologies to forecast, analyze and optimize reliability and risks for complex systems
The paper is concerned with the application of the original mathematical models and supporting them software technologies to forecast, analyze and optimize reliability and risks for complex systems (system is defined as a combination of interacting elements organized to achieve one or more stated purposes). Functionality and usability to analyze information system processes and standard processes in system life cycle are presented.
Rational use of the proposed results allows to go «from a pragmatical filtration of information to generation of the proved ideas and effective decisions». Effects are demonstrated by examples. [full text]
Dagkinis Ioannis, Lilas Theodoros, Nikitakos Nikitas
Operational failure prevention methodology for offshore systems using multiple criteria decision-making process
A framework for decision analysis, which has been applied on an operational offshore system and is based on a multiple criteria decision making (MCDM) process, is presented in this paper. This provides a generic methodology for the evaluation of alternatives and implementation of operational and design improvements based on the experience gained from past failures. The Failure Modes and Effects Analysis (FMEA) method is modified and used as a significant criterion together with Analytic Hierarchy Process (AHP) in order to enhance the decision making process. The mathematical model of AHP identifies and combines the weight of changes, as well as the results of modified FMEA. This combination takes into account possible interactions among the causes of failure by integrating several elements, enhancing the FMEA method. Next, the paper describes a decision model that incorporates also decision maker’s subjective assessments and is suitably applied to an autonomously operating floating structure. This decision making technique, enables the manipulation of both qualitative assessments and quantitative metrics in order to improve final judgments and, in general, advance the operation of the complex floating system. [full text]
Eid Mohamed, Souza de Cursi Eduardo, El Hami Abdelkhalak
Towards the development of a topological model to assess networks performance: connectivity, robustness and reliability
Networks are the widest spreading system which Mankind has ever developed, today. New needs, services, and use are created each day where network systems represent the most critical aspect. Additionally, the interconnection between networks of different types is growing as never. This acceleration of interconnection of all sorts brings to the front scene the issue of performance measure in networks design and operation. For that purpose, engineers are orienting their major efforts towards the development of methods, models and codes to assess and measure networks performance in terms of probability of being connected.
From this stand point of view, the engineers’ attention is mainly focused on defining the network “Connectivity” and measuring it, in different manner, using probabilities. Subsequently, we are observing an accelerating course towards quantitative probabilistic models to describe and assess networks’ Connectivity, since the sixties. Modelling realistic networks is still far from being satisfactorily achieved using quantitative probabilistic models.
On the other hand, little room has been lift to exploring the potential of graphical and topological models to develop qualitative and semi- quantitative models in order to assess networks performance. In this paper, we have tried to explore the potential of the topological modelling and are proposing an original one. The proposed model is still in its earliest phase of development. But, it sounds very promoting at that stage of maturation. According to this model, the term “performance” may be extended, beyond the “connectivity probabilistic concept”, to “robustness” and to a “deepest insight” of the “connectivity concept” itself. The impact is immediate on the way the “reliability concept” would be extended to cover network systems. [full text]
Kosmowski Kazimierz T.
Current challenges and methodological issues of functional safety and security management in hazardous technical systems
The aim of this article is to identify problems of the risk assessment of the electric / electronic / programmable electronic (E/E/PE) systems concentrating on the functional safety and security aspects. These aspects should be considered in an integrated way in the system life cycle. The role of functional safety solutions is effective reducing the risk from unacceptable level. The risk is defined as a combination of the probability of occurrence of harm and the severity of that harm. Security is concerned with the protection of assets including the E/E/PE systems or safety instrumented systems (SISs) from potential threats including cyber attacks. This article deals with current challenges and methodological issues of integrating the functional safety and security aspects of the programmable systems’ operation for the control and protection of hazardous industrial systems.[full text]

Woch Marta
Analysis and comparison of reliability measures of critical points
In this work, algorithms have been used to compare the reliability measure of helicopter structure critical points. Reliability index, Cornell’s reliability index and Hasofer-Lind’s reliability index have been calculated and analysed. Inputs to the algorithms, stress and strength were generated by using the Markov chain model based on actual flight records of helicopters. With this approach, results of methods for determining the reliability of critical points of a helicopter’s structure are properly founded. [full text]
Kuligowska Ewa
Preliminary Monte Carlo approach to complex technical system reliability analysis
The paper explores the mathematical and computer modeling of complex technical systems related to their operation processes. The complex technical system with the reliability structure and components’ reliability parameters changing at the various operation states is defined. The selected system operation process parameters and the hypothetical distribution functions of the conditional sojourn times at the operation states are defined and identified. The reliability functions of the multistate system and components are introduced and their parameters are identified. The Monte Carlo simulation method is proposed to the complex system reliability evaluation. Moreover, the proposed theoretical and simulation tools are supported with the practical application to the multi-state port oil piping transportation system reliability analysis.[full text]
Kołowrocki Krzysztof, Soszyńska-Budny Joanna
Preliminary approach to safety analysis of critical infrastructures
In the paper the new results of the safety investigations of the multistate complex systems with dependent components at variable operation conditions called critical infrastructures are presented. The multi-state safety function of the critical infrastructure system is defined and determined for an exemplary critical infrastructure.
In the developed models, it is assumed that the system components have the multistate exponential safety functions with interdependent departures rates from the subsets of the safety states.[full text]
Berg Heinz Peter
Assessing the risk of the transport of radioactive material
Transport of dangerous goods are always under critical observation of the public, in particular in case of transport of spent fuel or radioactive waste. In both cases transports are often crossing borders of countries, e.g., waste resulting from reprocessing of spent fuel. The transports could take place by ships, trucks, rails and airplanes and these options and the resulting risks are compared. Transport risk includes health and safety risks that arise from the exposures to workers and members of the public to radiation from shipments Moreover, it is shown that the more modern approach of risk-informed decision making elaborated for application to nuclear installations can also be applied to assess the risk of the transport of radioactive material. [full text]
Braband Jens, Griebel Stephan
Advances in risk analysis in railway signalling
The paper is concerned with the developments of risk analysis during the last decade, starting from full range quantitative risk analysis of e.g. a level crossing based on the CENELEC standards EN50126 and EN50129 up to semi-quantitative methods for risk analysis. To expedite this shift from pure quantitative approaches to a more categorized approach were the perennial challenges of insufficient availability of accurate data and the sheer complexity of the reality to be model quantitatively. The article contains both a presentation of a complete quantitative risk analysis for a level crossing as well as a discussion of the crucial points that will need improvement on the basis of a new semi-quantitative standard for risk analysis that has been issued as a national pre-standard in Germany. The relation to the current regulations stipulated by the European Railway Agency and recent publications on this issue are presented as well. [full text]
Zukowska Joanna
Road safety analysis in Poland using time-series modelling techniques
A number of international studies argue that there is a correlation between the number of traffic fatalities and the degree of public activity. The studies use the unemployment rate to support that argument. As unemployment grows miles travelled fall, a factor known to affect road safety. This relationship seems to be true for Poland, as well. The model presented in the paper is intended to prove it. It is a structural time-series local level model with the explanatory variable (the unemployment rate) and some interventions. Because of the dynamic nature of traffic safety developments it lends itself very well to modelling in that way. [full text]
Montewka Jakub
Risk modelling and management in large-scale, distributed transportation systems
Large-scale distributed transportation systems can pose various risks in terms of fatalities, environmental pollution, or loss of property. In particular, accident where a vehicle carrying large number of passengers is involved may pose a high risk with respect to human casualties, moreover it will immediately raise a public and political concern. This is an issue in case of maritime transportation systems (MTS), as the biggest ships nowadays can carry up to 8500 people at once (m/s Oasis of the Seas). Thereby lot of effort has been put to increase safety of ships carrying passengers; however the holistic approach to model and manage the risk existing in the MTS is still missing. This paper makes an attempt to fill this gap, by presenting a data-driven model evaluating risk level in the existing MTS and by introducing a systematic methodology for mitigating the risk. Moreover the MTS operating in the Gulf of Finland under non-ice conditions is addressed, where heavy passenger traffic is observed. [full text]
Rasmussen Finn Mølsted, Glibbery Karis Anneke Kürstein, Melchild Kristina, Hansen Martin Gamborg, Jensen Toke Koldborg, Lehn-Schiøler Tue, Randrup-Thomsen Søren
Quantitative assessment of risk to ship traffic in the fehmarnbelt fixed link project
Rambøll is on behalf of Femern A/S carrying out navigational studies of the vessel traffic conditions in the Fehmarnbelt in connection with the establishment of a future Fehmarnbelt fixed link, a 19 km long bridge or immersed tunnel connection crossing the Fehmarnbelt. The focus is on documenting safety and efficiency for the vessel traffic when a fixed link is crossing the Fehmarnbelt. Rambøll has developed the ShipRisk software package to perform the quantitative risk assessments in the Fehmarnbelt fixed link project. Focus in this article is on describing the background for estimating frequencies of ship accidents in ShipRisk and describe factors influencing the accident scenarios and present the work performed for testing and verifying the model. [full text]
Berg Heinz Peter, Röwekamp Marina
Approach to assess fire risk for nuclear power plants
The results of the first fire risk assessments on an international level have shown that fires are one major contributor to the risk of a nuclear power plant depending on the plant specific fire protection concept. Therefore, fire risk assessment has today become an integral part of the probabilistic safety assessment of nuclear power plants in addition to deterministic analyses. Based on existing guidance documents a state-ofthe-art approach for performing probabilistic fire risk assessment has also been developed in Germany. This approach has been exemplarily and completely applied to a German nuclear power plant with boiling water reactor for the full power states PSA. The general approach outlines the steps necessary for performing fire risk assessment and the prerequisites for a sound and traceable database. [full text]
Hellmich Mario, Berg Heinz-Peter
An importance measure for multi-component systems with Semi-Markov dynamics
We consider semi-Markov reliability models of multi-component systems with a discrete state space, general enough to include systems with maintenance or repair. We assume that for all system states the functioning or failure of each component is specified. In this setup we propose a component importance measure which is close in spirit to the classical steady state Barlow–Proschan importance measure for repairable binary coherent systems. We discuss our importance measure to some extent, highlighting the relation to the classical Barlow–Proschan measure, and present formulas expressing it in terms of quantities easily obtained from the building blocks of the semi-Markov process. Finally an example of a two-component cold standby system with maintenance and repair is presented which illustrates how our importance measure can be used in practical applications. [full text]