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SSARS 2009 Voulme 2

Kołowrocki Krzysztof, Soszyńska Joanna Methods and algorithms for evaluating unknown parameters of operation processes of complex technical systems |

The paper objectives are to present the methods and tools useful in the statistical identifying unknown parameters of the operation models of complex technical systems and to apply them in the maritime industry. There are presented statistical methods of determining unknown parameters of the semi-markov model of the complex technical system operation processes. There is also presented the chi-square goodness-of-fit test applied to verifying the distributions of the system operation process conditional sojourn times in the particular operation states. Applications of these tools to identifying and predicting the operation characteristics of a ferry operating at the Baltic Sea waters are presented as well. [full text] |

Kołowrocki Krzysztof, Soszyńska Joanna Methods and algorithms for evaluating unknown parameters of components reliability of complex technical systems |

The paper objectives are to present the methods and tools useful in the statistical identifying the unknown parameters of the components reliability and safety of complex industrial systems and to apply them in the maritime industry. There are presented statistical methods of estimating the unknown intensities of departure from the reliability state subsets of the exponential distribution of the component lifetimes of the multistate systems operating in various operation states. The goodness-of-fit method applied to testing the hypotheses concerned with the exponential form of the multistate reliability function of the particular components of the complex technical system in variable operations conditions is suggested. An application of these tools to reliability characteristics of a ferry operating at the Baltic Sea waters is presented as well.[full text] |

Kołowrocki Krzysztof, Soszyńska Joanna Safety and risk evaluation of Stena Baltica ferry in variable operation conditions |

Basic safety structures of multi-state systems of components with degrading safety states related to their variable operation conditions are defined. For these systems the conditional and unconditional multi-state safety functions are determined. A semi-markov process for the considered systems operation modelling is applied. Further, the paper offers an approach to the solution of a practically important problem of linking the multi-state systems safety models and the systems operation processes models. Theoretical definitions and results are illustrated by the example of their application in the safety and risk evaluation of the Stena Baltica ferry operating at the Baltic Sea. The ferry transportation system has been considered in varying in time operation conditions. The system safety structure and its components safety functions were changing in variable operation conditions.[full text] |

Kołowrocki Krzysztof, Soszyńska Joanna Statistical identification and prediction of the port oil pipeline system’s operation process and its reliability and risk evaluation |

In the paper a Semi-markov processes are used to construct a general model of complex industrial systems’ operation processes. Main characteristics of this model are determined as well. In particular case, for a port oil pipeline transportation system, its operation states are defined, the relationships between them are fixed and particular model of its operation process is constructed and its main characteristics are determined. Further, the joint model of the system operation process and the system reliability is defined and applied to the reliability and risk evaluation of the port oil pipeline transportation system. [full text] |

Kosmowski Kazimierz Functional safety analysis including human factors |

In this paper selected aspects of human factors are discussed that should be taken into account during the design of safety-related functions for a complex hazardous installation and its protections. In such installations the layer of protection analysis (LOPA) methodology is often used for simplified risk analysis based on defined accident scenarios. To control the risk the safety instrumented functions (SIFs) are identified and their safety integrity levels (SILs) determined with regard to results of risk assessment. Given SIF is to be realised by the electric/ electronic/ programmable electronic system (E/E/PES) or safety instrumented system (SIS) and the human-operator. The SIL is to be verified according to requirements and criteria given in international standards IEC 61508 and IEC 61511. Selected issues related to designing the alarm system (AS) with regard to human factors are outlined. Some aspects of human reliability analysis (HRA) as a part of human-machine interface (HMI) assessing and probabilistic modelling of the system are shortly discussed.[full text] |

Kowalski Marcin, Magott Jan, Nowakowski Tomasz, Werbińska-Wojciechowska Sylwia Analysis of transportation system with the use of Petri nets |

The paper considers problem of city transportation system performance. Reliability analysis of such a complex system is complicated by several factors. One of them is the possibility of logistic support elements unreliability defined as unavailability of spare elements when desired, what in result may lead to decrease of performance of the system being supported. Thus, both systems must be considered in a single model. However, the simultaneous setting of all structural parameters (e.g. redundancy, repair shop capacity) and control variables (e.g. spare part inventory levels, maintenance policy parameters, time resource) is mathematically a hard problem. This paper investigates Petri net model of the system with the use of Monte Carlo simulation as a solution technique. Comparison of the simulation results with characteristics of real-life system is given. [full text] |

Kwiatuszewska-Sarnecka Bożena Models of reliability and availability improvement of series and parallel systems related to their operation processes |

Integrated general models of approximate approaches of complex multi-state series and parallel systems, linking their reliability and availability improvement models and their operation processes models caused changing reliability and safety structures and components reliability characteristics in different operation states, are constructed. These joint models are applied to determining improved reliability and availability characteristics of the considered multi-state series and parallel systems related to their varying in time operation processes. The conditional reliability characteristics of the multi-state systems with hot, cold single reservation of component and the conditional reliability characteristics of the multi-state systems with reduced rate of departure by a factor of system components are defined. [full text] |

Lisi Roberto, Milazzo Maria Francesca, Maschio Giuseppe Quantitative assessment of explosion risk in workplaces |

The Directive 99/92/EC deals with the safety and health protection of workers potentially exposed at explosive atmospheres. The application of this Directive requires the assessment of specific risks due to the presence of potentially explosive atmospheres. These can generally be originated by releases of flammable substances typical of industries classified at major hazard, but they often could be generated also in all other industries where flammable materials are handling. Risk assessment of explosive atmospheres is required in both the cases, to this purpose, in this article a quantitative approach has been proposed. The paper describes the main aspects of the methodology, based on a probabilistic risk assessment, and finally its application to a case-study.[full text] |

Lumanpauw Ernest, Habibullah Mohamed Salahuddin, Kołowrocki Krzysztof, Soszyńska Joanna, Xie Min A computational tool for general model of industrial systems operation processes |

The complexities of real industrial systems operation processes require computational methods that can analyze the large data and evaluate the behaviours of these systems. The use of methods such as Bayesian Network, Formal Safety Assessment and Statistical-Model based method were discussed as possibilities. Of which, a computational tool, based on the Semi-Markov model, was developed. This tool was then applied to analyze the behaviour of the operation processes of the oil transportation system in Dębogórze, Poland. The analyses showed that the computational solutions generated compared favorably well with the analytical calculations, enabling possible extensions of the tool to include reliability and optimization evaluations to be explored.[full text] |

Mennis Evangelos, Nikitakos Nikitas, Platis Agapios Ship’s diesel electrical system availability modeling |

One of the most critical systems for a ship operation is the diesel generator set. This is why the ship preserves four different diesel generators except the power battery packs. The paper describes the generator operation and the main failure conditions. Assuming that the failure rate of the system parts is constant the paper shows how the diesel generator system could be modelled in the context of Markov theory. [full text] |

Milczek Beata Examples of series-“m out of k” systems and their limit reliability functions |

The paper is concerned with mathematical methods in asymptotic approach to systems reliability analysis. The complexity of the reliability investigation of large-scale systems is proposed to be approximately solved by assuming that the number of system components tends to infinity and finding the limit reliability function of the system. Some general results in the form of auxiliary theorems and examples of limit reliability functions of homogeneous and regular series-“m out of k” systems with exponential and Weibull reliability functions of system components are presented.[full text] |

Młyńczak Marek Physical and reliability aspects of failure in mechanical objects |

Mechanical objects are operated in real world where degradation of material components and variability of processes managed by a man are the main factors influencing its efficiency. Machine degradation is a long-lasting process concerning its material structure, components and connections. Loss of machine operation ability is due to failures caused by wear and tear, fatigue, corrosion, overloading, material ageing and many other destructive processes. It is observed close relation between failure modes and reliability models so that knowledge about failures may help analysts creating reliability models and determine the best operational decisions. In the paper it is discussed relation between physical phenomenon and theoretical models as a common platform of decision processes.[full text] |

Nowakowski Tomasz, Werbińska-Wojciechowska Sylwia Models of logistic support systems |

We present an overview of some recent developments in the area of inventory planning and maintenance scheduling issues. The emphasis is on spare part inventory models, which authors divided into four main groups of models: models of optimal spare part inventory policy for system under PM, number of spare parts optimization models, storage reliability models, multi-echelon systems models. Later, in the paper there is considered the time dependent system of systems where the system total task must be executed during the constrained time resource. There is used the simulation approach to investigate the influence of parameters of the procurement process (order quantity, critical inventory level, lead-time length) on the system of systems behavior.[full text] |

Pantanali Claudio, Bianco Cristina Quantitative OHS evaluation: RATE procedure compared with traditional reliability methodologies |

The most careful and consolidated risk analysis methods, as FTA, ETA, FMEA/FMECA, focus attention on system reliability. But, looking at OHS, a deep analysis on European data on accidents at work and on work environment in general, shows how reliability is only one aspect of safety problem. These methods then are hardly adaptable when the main aim is to obtain a quantitative assessment of risk for workers; besides, other methodologies are nearest to OHS but give only qualitative results like HAZOP, or base their analysis on not-dimensional values, fixed by analyst on personal experiences, like methods proposed by UNI EN 1050, by standard MIL-STD-882c and by AISS. RATE is proposed as a new quantitative methodology for OHS, particularly dedicated to SMEs considered as the most interesting from these aspect. The paper compares hypothesis and procedures which traditional quantitative methodologies and RATE are based on, to give evidence at the main approach aspects that have to be modified in order to move from reliability to OHS.[full text] |

Rahim Yousif, Refsdal Ingbjørn, Kenett Ron The 5C model: a new approach to asset integrity management |

As organizations grow more complex in operation and more global in scope, assets and technical integrity become key success factors. A company's asset integrity business process needs to be mapped in order to 1) provide a proper overview of operation and business processes, 2) identify all critical interfaces and 3) ensure that all gaps and overlap in processes are eliminated. Achieving asset integrity requires companies to sustain their activities and identify the hazards, weaknesses and objectives of their strategic assets. Technical integrity emphasizes a complete overview of technical conditions and related information, and the ability of the companies to document the technical state of its assets. It is based on an integrated view of the current state of operations, and the identification of all critical interfaces, in order to ensure that all gaps and unnecessary overlaps in processes are eliminated. Companies look increasingly at their asset integrity management system as a means to extend the life of their assets, beyond the original design conditions and production capacity. Establishing an asset integrity management system requires the documentation of the company’s technical integrity management, a strategy and the processes for carrying it out, identifying gaps; selecting corrective interventions and conducting follow up actions. The paper will discuss various aspects of asset integrity management, including its planning and implementation. We begin with an introduction to asset technical integrity, provide some theoretical backgrounds, present a model we call 5C and conclude with a summary and discussion.[full text] |

Tanguy Christian Mean time to failure for periodic failure rate |

The paper is concerned with the determination of the Mean Time To Failure (MTTF) in configurations where the failure rate is periodical. After solving two configurations exactly, we show that when the period of the failure rate oscillations is small with respect to the average failure rate, the MTTF is essentially given by the inverse of the average failure rate, give or take corrections that can be expressed analytically. This could be helpful in the description of systems the environment of which is subject to changes.[full text] |

Valis David, Vintr Zdenek, Koucky Miroslav Contribution to reliability analysis of highly reliable items |

In recent years the intensive efforts in developing and producing electronic devices have more and more critical inference in many areas of human activity. Engineering is one of the areas which have been also importantly affected. The paper deals with dependability namely reliability analysis procedure of a highly reliable item. The data on manufacturing and operating of a few hundred thousands pieces of electronic item are available and they are statistically a very important collection/set. However, concerning some items the manufacturing procedure was not checked and controlled accurately. The procedure described in the paper is based on the thorough data analysis aiming at the operating and manufacturing of these electronic elements. The results indicate some behaviour differences between correctly and incorrectly made elements. It was proved by the analysis that dependability and safety of these elements was affected to a certain degree. Although there is a quite big set of data the issue regarding the statistical comparability is very important.[full text] |

Valis David, Vintr Zdenek, Koucky Miroslav Selected approaches for reliability comparison of highly reliable items |

The application of electronic elements introduces a number of advantages as well as disadvantages. The paper deals with advanced method of dependability - reliability analysis procedure of a highly reliable item. The data on manufacturing and operating of a few hundred thousands pieces of the highly reliable devices are available and from the statistical point of view they are very important collection/set. However, concerning some pieces of the items the manufacturing procedure of them was not made, controlled and checked accurately. The procedure described in the paper is based on the thorough data analysis aiming at the operation and manufacturing of these electronic elements. As the data sets collected are statistically non-coherent the objective of the paper is to make a statistical assessment and evaluation of the results. Failure rates calculations and their relation comparability regarding the both sets are presented in the paper. [full text] |

Zając Mateusz, Valis David Fundamental risk assessment in reduced data conditions in particular example |

The paper represents discussion about risk assessment for transhipment system in reduces data condition. As a particular example transhipment system is presented. Article can be treated as first estimation. Future work and objectives are characterized in the end. [full text] |

Zamojski Wojciech Dependability of services networks |

In the tutorial paper systems and networks are considered as a union of all their resources essential for the realization of predicted tasks. System dependability is discussed with respect to the occurrence of incidents and treats that may cause damage to the system resources and, in consequence, to the executed tasks. The maintenance policy system is based on two main concepts: detection of unfriendly events and system responses to them. It is proposed to analyse the network system from the functional and user point of view, focusing on business service realized by a network system. Services networks are modelled as the Petri net models which may be useful for analyses of dependability parameters and for setting up a maintenance policy of the services net. [full text] |