| Bąk Andrzej, Gucma Lucjan Risk assessment of ships collision with moored ships by statistical method |
| The paper presents simplify statistical method of risk assessment of collision with moored ships. The model is based on statistical – historical data and could be used for designing the places of dangerous cargo discharge or safety analysis of existing ones.[full text] |
| Berg Heinz-Peter, Krauß Matias Resilience of nuclear plants in case of hazards |
| Internal and external hazards analysis methods have been used recently to evaluate operating nuclear power plants (NPP) and to identify the resilience of NPP in case of hazards and potential needs for modification of plant systems and procedures as well as to support design of new plants The external hazards risk contribution has been modeled in many NPP PSA (at least for some external hazards) over the last decade, including events occurring during shutdown and low power operations. Recently, a revision of the German nuclear safety regulations has been successfully completed and these regulations entitled “Safety Requirements for Nuclear Power Plants”, also requiring a detailed investigation of internal and external hazards and combinations of different hazards applying deterministic and probabilistic safety assessment methods.[full text] |
| Berg Heinz-Peter Development of a framework of safety goals for nuclear installations and its application in Germany |
| The International Atomic Energy Agency has started a few years ago a project to enhance the existing framework for safety goals for nuclear installations and currently is finalizing a publication aimed to provide guidance for a more holistic approach to establishing and utilizing safety goals for nuclear installations. The intention was to develop a more consistent and holistic framework for safety goals that would be composed of a hierarchical structure of qualitative concepts (e.g. defense in depth, various safety requirements) and quantitative risk metrics. The safety goals should be technology neutral at the higher level and should cover both normal operation and accident conditions as well as the risk to workers, public, and the environment. In the paper the development of a hierarchical framework for safety goals is described including a methodology to derive lower-(more technical) safety goals from the higher goals. Moreover a process for assessing the degree of compliance with the safety goals and their consistent use is provided. As an example the developed framework is applied to the German regulatory framework for nuclear installations but focused on nuclear power plants.[full text] |
| Besson Mathieu, Tanguy Christian, Grall Antoine On the average file unavailability for specific storage disk arrangements in Cloud systems |
| Cloud computing is a growing field since data storage is becoming ever more decentralized. Providers of Cloud solutions want to insure the safety and availability of their customers’ data. In order to increase these performance indices, several storage policies have been implemented: replication, erasure codes, etc. A few of them rely on randomized procedures. In this paper, we focus on the influence of a specific storage policy on the availability of a given file. Taking only disk failures into account, we provide a general formula for the average file unavailability U ̅, which is a generalization of the well-known k-out-of-n problem, to which it reduces when disks are identical. We then calculate U ̅ for several configurations when disks have different reliabilities, and show that the disk arrangement has a major impact on the result. We also provide an approximation which could be helpful for more complex arrangements. [full text] |
| Blokus-Roszkowska Agnieszka, Kołowrocki Krzysztof Reliability analysis of multistate series systems with dependent components |
| In the paper an approach to the reliability analysis of multistate series systems assuming their components dependency according to the local load sharing rule is presented. There is introduced the local load sharing model of components dependency (of departures from the reliability states subsets) and the reliability function of a multistate series system with dependent components is determined. These results are also presented in case system components have exponential reliability functions and in this case basic reliability characteristics are given.[full text] |
| Blokus-Roszkowska Agnieszka, Kołowrocki Krzysztof Reliability of the exemplary multistate series system with dependent components |
| In the paper a multistate approach to reliability analysis of series systems with dependent components according to the local load sharing rule is proposed. As a particular case, the reliability function of a multistate series system composed of dependent components having exponential reliability functions is determined. The mean values and standard deviations of the multistate system lifetimes in the reliability state subsets and the mean values of its lifetimes in the particular reliability states are determined. Application of the proposed model of components’ dependency to the reliability analysis of the exemplary system is presented. The exemplary system risk function and the moment of exceeding by the system the critical reliability state are given.[full text] |
| Bogalecka Magda, Kołowrocki Krzysztof Modeling, identification and prediction of environment degradation initiating events process generated by critical infrastructure accidents |
| The paper is the first part of the probabilistic general model of critical infrastructure accident consequences including the process of initiating events, the process of environment threats and the process of environment degradation models. Basic notions concerned with the events initiating dangerous for the environment after the critical infrastructure accident or its loss of safety critical level are introduced. The methods and procedures of estimating the process of initiating events unknown basic parameters and identifying the distributions of its conditional sojourn times at its states are proposed. Under these all assumptions from the constructed model and after its unknown parameters identification, the main characteristics of the process of the initiating events are predicted. Finally, the proposed model and methods are applied to modelling, identification and prediction of the process of initial events generated by the critical infrastructure defined as a ship operating in the Baltic Sea basin.[full text] |
| Bogalecka Magda, Kołowrocki Krzysztof The process of sea environment threats generated by hazardous chemicals release |
| The kinds of threats coming from chemicals released as a result of sea accident are distinguished. An exemplary procedure of defining states of the sea environment threats process generated by hazardous chemicals is presented. The interrelation between the sea environment threats and this environment degradation process is discussed and finally, a preliminary approach to a general modelling and prediction of the process of the environment threats caused by the process of initiating events generated by critical infrastructure accidents is presented.[full text] |
| Dziula Przemysław, Rosiński Adam, Siergiejczyk Mirosław An approach to analysis of transition rates between the critical infrastructure systems safety states |
| The article is showing a concept of critical infrastructure system’s safety states model. Model construction is basing on notions specified in acts of law regarding crisis management and critical infrastructure protection, and other studies concerning them. Implementation of crisis management issues and problems into technical systems safety states modelling, can illustrate processes related to transitions between the critical infrastructure systems safety states. Then, the paper is showing some concept of analysis of transition rates between the critical infrastructure systems safety states, by means of taking into account factors describing their actual conditions and parameters.[full text] |
| Eid Mohamed, El Hami Abdelkhalak, Souza de Cursi Eduardo, Kołowrocki Krzysztof, Kuligowska Ewa, Soszyńska-Budny Joanna Critical Infrastructures Protection (CIP) – coupled modelling for threats and resilience |
| Critical Infrastructure Protection (CIP) requires the development of models and tools able to describe and simulate the threats’ and the Critical Infrastructure’s (CI) dynamic behaviour. However, these modelling activities are very often carried out separately for threats and for CI behaviour. An effective assessment of the CI’s resilience and preparedness requires real coupled models of threats dynamic and CI’s one. The authors develop some basic ideas about coupled modelling in the sense of coupling the dynamics of the threat with that of the CIs, within a stochastic modelling approach. Such coupled dynamic models would enhance the effectiveness of our capabilities to assess CI’s resilience and to help in decision making for crisis management.[full text] |
| Grabski Franciszek Decision problem for a finite states change of semi-Markov process |
| In the paper there are presented basic concepts and some results of the theory of semi-Markov decision processes. The algorithm of optimization a SM decision process with a finite number of state changes is discussed here. The algorithm is based on a dynamic programming method. To clarify it the SM decision model for the maintenance operation is shown.[full text] |
| Guze Sambor Numerical application of the SPEA algorithm to reliability multi-objective optimization |
| The main aim of the paper is the computer-aided multi-objective reliability optimization using the SPEA algorithm. This algorithm and the binary knapsack problem are described. Furthermore, the computer program that solves the knapsack problem with accordance to SPEA algorithm is introduced. Example of the possible application of this program to the multi-objective reliability optimization of exemplary parallel-series system is shown.[full text] |
| Hadjistassou Constantinos, Bratskas Romaios, Koutras Nikolaos, Kyriakides Alexandros, Charalambous Elisavet, Hadjiantonis Antonis M. Safeguarding critical infrastructures from cyber attacks: A case study for offshore natural gas Assets |
| The majority of operations, as well as the physical and chemical processes, which take place on offshore Natural Gas installations are controlled by computer systems. These computer systems are vulnerable to cyber-attacks. If successful, such attacks can have disastrous and far-reaching consequences, including human casualties, large-scale pollution, and immense financial cost. In this paper we identify one possible way that an attacker can inflict material damage, by altering the parameters of the gas hydrate inhibition system. The formation of gas hydrates can completely halt operations for a prolonged period of time, could damage equipment, and directly endanger human lives. To raise the level of protection we propose the implementation of two lines of defense the second based on machine learning algorithms. Appreciating the sophistication of attacks, the inherent risks and complexity of multi-billion offshore energy assets we highlight the need for further research intended to address safety loopholes.[full text] |
| Karcz Rafał Method of performing Design FMEA on electronic circuit diagrams |
| Existing method of performing FMEA for electronic diagrams is time consuming task. For complex systems analysis of every single component failure mode and its effect deeply involves design team and blocks resources availability for long time. Method presented in this paper allows effective analysis of design failure modes using FMEA approach carrying so called Time to Acceptable Analysis (TTAA) constraint.[full text] |
| Kołowrocki Krzysztof, Kuligowska Ewa, Soszyńska-Budny Joanna Reliability assessment of an exemplary system operating at variable conditions |
| The reliability analysis of a multistate complex system subjected to varying in time its operation process is performed. A semi-Markov process is applied to construct the multistate model of the system operation process and its main characteristics are determined. Analytical linking of the system operation process model with the system multistate reliability model is proposed to get a general reliability model of the complex system operating at varying in time operation conditions and to find its reliability characteristics. The constructed integrated general model of a complex multistate system reliability, linking its reliability model and its operation process model and considering variable at different operation states its reliability structure and its components reliability parameters is applied to the reliability evaluation of an exemplary system.[full text] |
| Kołowrocki Krzysztof, Kuligowska Ewa, Soszyńska-Budny Joanna Monte Carlo simulation application to reliability assessment of an exemplary system operating at variable conditions |
| A semi-Markov process is applied to construct the multistate model of the system operation process and its main characteristics are determined. Analytical linking of the system operation process model with the system multistate reliability model is proposed to get a general reliability model of the complex system operating at varying in time operation conditions and to find its reliability characteristics. The Monte Carlo simulation algorithm based on the integrated general model of a complex multistate system reliability, linking its reliability model and its operation process model and considering variable at different operation states its reliability structure and its components reliability parameters is applied to the reliability evaluation of an exemplary system. Next the results of this simulation method application are illustrated and compared with the results obtained by the analytical method.[full text] |
| Kołowrocki Krzysztof, Kuligowska Ewa, Soszyńska-Budny Joanna Reliability of complex system under operation process influence – Monte Carlo simulation Approach |
| The paper presents Monte Carlo simulation method applied to the reliability evaluation of a multistate system subjected to a variable multistate operation process. The system operation process model is linked with the system reliability model and proposed to get a general reliability model of the complex system operating at varying in time operation conditions and to find its reliability characteristics. The Monte Carlo simulation algorithm based on the integrated general model of a complex multistate system reliability, linking its reliability model and its operation process model and considering variable at different operation states its reliability structure and its components reliability parameters is applied to the reliability evaluation of port grain transportation system. Next the results of this simulation method application are illustrated and compared with the results obtained by the analytical method.[full text] |
