SSARS 2007 Volume 2
Knopik Leszek
Some remarks on mean time between failures of repairable systems
This paper describes a simple technique for approximating the mean time between failures (MTBF) of a system that has periodic maintenance at regular intervals. We propose an approximation of MTBF for vide range of systems than IFRA class of distributions.[full text]
Kobyliński Lech
Stability and safety of ships: holistic and risk approach
Present stability regulations developed over the years by IMO reached definite conclusion with the adoption of the Revised Draft of the Intact Stability Code. The criteria included there are design criteria of the prescriptive nature, based mainly on statistics of stability casualties. Currently IMO is considering development of criteria based on ship performance. Concept of such criteria is, however, at present not agreed. The criteria are working comparatively well with regard to the majority of conventional ships, however advent of very large and sophisticated ships of non-conventional features caused that those criteria may be inadequate. The author advances the idea consisting of application of safety assessment and risk analysis using holistic and system approach to stability. Safety against capsizing (or LOSA accident) is a complex system where design, operational, environmental and human factors have to be taken into account. Although this seems to be a very complex task, in the opinion of the author it may be manageable and could be applied for safety assessment of highly sophisticated and costly ships.[full text]
Kołowrocki Krzysztof
Reliability modelling of complex systems - Part 1
The paper is concerned with the application of limit reliability functions to the reliability evaluation of large systems. Two-state large non-repaired systems composed of independent components are considered. The asymptotic approach to the system reliability investigation and the system limit reliability function are defined. Two-state homogeneous series, parallel and series-parallel systems are defined and their exact reliability functions are determined. The classes of limit reliability functions of these systems are presented. The results of the investigation concerned with domains of attraction for the limit reliability functions of the considered systems and the investigation concerned with the reliability of large hierarchical systems as well are discussed in the paper. The paper contains exemplary applications of the presented facts to the reliability evaluation of large technical systems.[full text]
Kołowrocki Krzysztof
Reliability modelling of complex systems - Part 2
Series-“m out of n” systems and “m out of n”-series systems are defined and exemplary theorems on their limit reliability functions are presented and applied to the reliability evaluation of a piping transportation system and a rope elevator. Applications of the asymptotic approach in large series systems reliability improvement are also presented. The paper is completed by showing the possibility of applying the asymptotic approach to the reliability analysis of large systems placed in their variable operation processes. In this scope, the asymptotic approach to reliability evaluation for a port grain transportation system related to its operation process is performed. [full text]
Kudzys Antanas
Transformed conditional probabilities in the analysis of stochastic sequences
The need to use unsophisticated probability-based approaches and models in the structural safety analysis of the structures subjected to annual extreme service, snow and wind actions is discussed. Statistical parameters of single and coincident two extreme variable actions and their effects are analysed. Monotone and decreasing random sequences of safety margins of not deteriorating and deteriorating members are treated, respectively, as ordinary and generalized geometric distributions representing highly-correlated series systems. An analytical analysis of the failure or survival probabilities of members and their systems is based on the concepts of transformed conditional probabilities of safety margin sequences whose statistically dependent cuts coincide with extreme loading situations of structures. The probability-based design of members exposed to coincident extreme actions is illustrated by a numerical example.[full text]
Kuo Way
Reliability wave in light of the nano development
This talk is based on the Editorial of IEEE Transactions on Reliability, December, 2006 and discusses a framework for applying reliability principles and practices to the emerging nano technology fields.[full text]
Kwiatuszewska-Sarnecka Bożena
On asymptotic approach to reliability improvement of multi-state systems with components quantitative and qualitative redundancy: series and parallel systems
The paper is composed of two parts, in this part after introducing the multi-state and the asymptotic approaches to system reliability evaluation the multi-state homogeneous series and parallel systems with reserve components are defined and their multi-state limit reliability functions are determined. In order to improve of the reliability of these systems the following methods are used: (i) a warm duplication of components, (ii) a cold duplication of components, (iii) a mixed duplication of components, (iv) improving the reliability of components by reducing their failure rate. Next, the effects of the systems’ reliability different improvements are compared. [full text]
Kwiatuszewska-Sarnecka Bożena
On asymptotic approach to reliability improvement of multi-state systems with components quantitative and qualitative redundancy: „m out of n” systems
The paper is composed of two parts, in this part the multi-state homogeneous „m out of n” systems with reserve components are defined and their multi-state limit reliability functions are determined. In order to improve of the reliability of these systems the following methods are used: (i) a warm duplication of components, (ii) a cold duplication of components, (iii) a mixed duplication of components, (iv) improving the reliability of components by reducing their failure rate. Next, the effects of the systems’ reliability different improvements are compared. [full text]
Meglouli H.
The probabilistic approach to the determination of consumption volumes and repairing the pieces of hydrocarbon’s equipments
The system of hydrocarbon equipments maintenance includes a group of activities and organisational measures and techniques. The principal equipment that we meet in the hydrocarbon domain consists of three parts: mechanical, electric and electronic and we are interested in the mechanical part, which is related to the problems of planning of the repairing of the equipments constructive elements. This research paper is devoted to the development of accompany approach to the problem of estimation or evaluation of consumption volumes and of pieces repairing, and equipments in taking into consideration the possibilities of the repeated rinses of restored pieces and of samples heterogenrionsity of identical equipments at the time of repairing. We give at the end an application of the viewed approach to the case of installations of gas turbine.[full text]
Rakowsky Uwe Kay
Fundamentals of the Dempster-Shafer theory and its applications to system safety and reliability modelling
The Dempster-Shafter Theory is well-known for its usefulness to express uncertain judgments of experts. This contribution shows how to apply the calculus to safety and reliability modelling, especially to expert judgement; Failure Modes, Effects, and Criticality Analysis; Event Tree Analysis, Fault Tree Analysis, and Reliability Centred Maintenance. Including a tutorial introduction to the Dempster-Shafer Theory, the differences between the Probability and the Dempster-Shafer Theory are discussed widely.[full text]
Rosická Zdena
Risk assessment related to information uncertainty components
Both organization and individuals deal with and manage knowledge. Considering the basic approach, we distinguish two principal clusters: tacit and explicit knowledge. The knowledge management is targeted at making the organization knowledge operation more effective and providing the right people with relevant information at the right time. Knowledge and information uncertainty components have become one of crucial assets of any company or organization. Their crucial potential consists in smart knowledge management handling, proficiency and art to fit the risky market needs better than competitors.[full text]
Ruiz-Castro Juan Eloy
A reliability system with loss of units
A repairable multi-component system subject to wear-out internal and accidental external failures with loss of units is developed. The system is composed of a finite number of units, including the main one and the others disposed in cold standby. If a repairable failure occurs, the main unit enters the repair channel. On the other hand, the unit is removed if the failure is non-repairable. A repairperson is considered. The distribution of the lifetime of the main unit is a general one and its phase-type representation is considered. Accidental failures occur according to a geometric discrete renewal process. The model is developed in detail. The availability and the conditional probability of different types of failures are calculated. An example illustrates the model and the number of units is optimised according to the average net reward. The results of this paper are implemented computationally with Matlab.[full text]
Sadovský Zoltán, Faško Pavol, Pecho Jozef, Bochníček Oliver, Mikulová Katarína, Šťastný Pavel
Collection and analysis of climatic measurements for the assessment of snow loads on structures
Climatological measurements for the assessment of snow loads on structures as practiced in Slovakia are discussed in the light of methodologies described in the relevant backgrounds to Eurocodes. The database of yearly snow load maxima based on the weekly measurements of water equivalent of snow cover on 660 rain-gauge stations in Slovakia recorded during the last 52 winter seasons is analysed. Special interest is focused on the influence of heavy snowfalls in the winters 2004/2005 and 2005/2006, particularly on the extreme cases observed. [full text]
Soszyńska Joanna
Systems reliability analysis in variable operation conditions
The semi-markov model of the system operation process is proposed and its selected parameters are defined. There are found reliability and risk characteristics of the multi-state series- “m out of ” system. Next, the joint model of the semi-markov system operation process and the considered multi-state system reliability and risk is constructed. The asymptotic approach to reliability and risk evaluation of this system in its operation process is proposed as well. [full text]
Stodola Jiri
Possibilities of traffic accidents and risk crash evaluation
This article analyses the traffic accident rate on roads and highways and possibilities of risk evaluation related to traffic accident occurrence based on factors that were the causes of accidents. A new term – risk of traffic accident occurrence is a product of probability of accident occurrence and its impacts. The results are presented by way of example that uses selected statistical data of the Czech Republic traffic accident rate between 1993 - 2001. The article provides a brief methodological procedure of evaluation of the traffic accident rate using the risk of traffic accident occurrence. [full text]
Szłapczyńska Joanna, Śmierzchalski Roman
Adopted isochrones method improving ship safety in weather routing with evolutionary approach
The paper is focused on adaptation of an isochrones method necessary for application to a weather routing system with evolutionary approach. Authors propose an adaptation of the isochrones method with area partitioning assuring that the route found by the adopted method would not cross land. In result, when applied to a weather routing system with evolutionary approach, this proposal facilitates creation of initial population, resulting with routes of reduced collision risk and low costs of passage.[full text]
Śmierzchalski Roman
Safe ship control system
The article presents a control system of ship motion in situations threatening with collision. The goal of the presented system is to support the navigator in decision making, with possible full replacement of his work in the future. In this article, it was introduced a system joining work of two computer techniques, evolutionary algorithms to marking of optimum path of passages and a fuzzy logic to control ship after set path of passage. The introduced system has to assure safe trip of a ship in any navigational conditions with regard of weather conditions and met navigational objects of static or dynamic nature. For testing of the operation, the system and the marine environment a simulator was used to present navigational situations in a 3D graphical mode at the poor hydro-and-meteorological conditions.[full text]
Vališ David
Reliability of complex system with one shot items
This article deals with modelling and analysis of the reliability of complex systems that use one-shot items during their operation. It includes an analysis of the impact of the reliability of used one-shot items on the resulting reliability of the system as a whole. Practical application of theoretical knowledge is demonstrated on an example of a model of reliability of an aircraft gun that was used for optimization of the gun’s design during its development and design. The analysed gun uses two types of one-shot items – rounds intended for conducting of fire and special pyrotechnic cartridges designed for re-charging a gun after a possible failure of the round.[full text]
Witkowska Anna, Śmierzchalski Roman
Non-linear backstepping ship course controller
A ship, as an object for course control, is characterised by a nonlinear function describing the static manoeuvring characteristics. One of the methods, which can be used, for designing a non-linear course controller for ships is the backstepping method. It was used here for designing the configurations of non-linear controllers, which were then applied for ship course control. The parameters of the obtained non-linear control structures were tuned to optimise the operation of the control system. The optimisation was performed using genetic algorithms. The quality of operation of the designed control algorithms was checked in simulation tests performed on the mathematical model of the tanker completed by steering gear.[full text]
Zio Enrico
Soft computing methods applied to condition monitoring and fault diagnosis for maintenance
Malfunctions in equipment and components are often sources of reduced productivity and increased maintenance costs in various industrial applications. For this reason, machine condition monitoring is being pursued to recognize incipient faults in the strive towards optimising maintenance and productivity. In this respect, the following lecture notes provide the basic concepts underlying some methodologies of soft computing, namely neural networks, fuzzy logic systems and genetic algorithms, which offer great potential for application to condition monitoring and fault diagnosis for maintenance optimisation. The exposition is purposely kept on a somewhat intuitive basis: the interested reader can refer to the copious literature for further technical details.[full text]
Zio Enrico, Baraldi Piero, Librizzi Massimom, Podofillini Luca, Dang H. Vinh
Sensitivity analysis of a fuzzy expert system for modelling dependencies in human operators’ emergency tasks
This paper analyzes the behaviour of a fuzzy expert system for evaluating the dependence among successive operator actions, through a sensitivity analysis on the fuzzy input partitioning and assessment. Preliminary results are presented with respect to a case study concerning two successive tasks of an emergency procedure in a nuclear reactor. Work is in progress to perform a thorough sensitivity analysis to generalize the results obtained.[full text]
Zio Enrico, Baraldi Piero, Popescu Irina Crenguta
Optimising a fuzzy fault classification tree by a single-objective genetic algorithm
In this paper a single-objective Genetic Algorithm is exploited to optimise a Fuzzy Decision Tree for fault classification. The optimisation procedure is presented with respect to an ancillary classification problem built with artificial data. Work is in progress for the application of the proposed approach to a real fault classification problem.[full text]
Zio Enrico, Sansavini Giovanni, Maja Roberto, Marchionni Giovanna
Analysis of the safety efficiency of a road network: a real case study
In this paper, recently introduced topological measures of interconnection and efficiency of network systems are applied to the safety analysis of the road transport system of the Province of Piacenza in Italy. The vulnerability of the network is evaluated with respect to the loss of a road link, e.g. due to a car accident, road work or other jamming occurrences. Eventually, the improvement in the global and local safety indicators following the implementation of a road development plan is evaluated.[full text]