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1

Mean residual lifetime assessment approach for a multi-state standby system

Karadayi Ebru, Funda Iscioglu

Eksploatacja i Niezawodność

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2023

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Vol. 25, no. 2

art. no. 166328

EN

In this paper, a new MRL assessment approach for a multi-state standby system is considered. The three-state system is backed up with a binary cold standby unit. Given that the system is at a specific state at time t, obtaining the MRL is worth considering in conducting the maintenance and repair plans of the system. For different degradation rates and time points, MRL results are examined. An HCTMP is considered for the degradation. Therefore, when the system is observed to be at its perfect state, the MRL decrease with an increase in all the failure rates of the system. However, when the system is observed to be at its partial state, the MRL is not affected by the increase in the failure rate pertained to the perfect state. The MRL when the system has known to be failed before time t and backed up with the standby unit increases with the time increase whereas the MRL when the system is at its perfect(or partial) state is constant when time increases. Moreover, cost evaluation of the system is analyzed. The results are supported with numerical examples and graphical representations.

2

Maintenance Evaluation and Optimization of a Multi-State System Based on a Dynamic Bayesian Network

Dahia Zakaria, Bellaouar Ahmed, Dron Jean-Paul

Management and Production Engineering Review

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2021

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Vol. 13, No. 3

3--14

EN

Nowadays, the main challenge in maintenance is to establish a dynamic maintenance strategy to significantly track and improve the performance measures of multi-state systems in terms of production, quality, security and even the environment. This paper presents a quantitative approach based on Dynamic Bayesian Network (DBN) to model and evaluate the maintenance of multi-state system and their functional dependencies. According to transition relationships between the system states modeled by the Markov process, a DBN model is established. The objective is to evaluate the reliability and the availability of the system with taking into account the impact of maintenance strategies (perfect repair and imperfect repair). Using the proposed approach, the dynamic probabilities of system states can be determined and the subsystems contributing to system failure can also be identified. A practical application is demonstrated by a case study of a blower system. Through the result of the diagnostic inference, to improve the performances of the blower, the critical components C, F, W, and P should be given more attention. The results indicate also that the perfect repair strategy can improve significantly the performances of the blower, while the imperfect repair strategy cannot degrade the performances in comparison to the perfect repair strategy. These results show the effectiveness of this approach in the context of a predictive evaluation process and in providing the opportunity to evaluate the impact of the choices made on the future measurement of systems performances. Finally, through diagnostic analysis, intervention management and maintenance planning are managed efficiently and optimally.

3

Reliability assessment of wind turbine generators by fuzzy universal generating function

Huang Tudi, Xiahou Tangfan, Li Yan-Feng, Qian Hua-Ming, Liu Yu, Huang Hong-Zhong

Eksploatacja i Niezawodność

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2021

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Vol. 23, no. 2

308--314

EN

Wind power has been widely used in the past decade because of its safety and cleanness. Double fed induction generator (DFIG), as one of the most popular wind turbine generators, suffers from degradation. Therefore, reliability assessment for this type of generator is of great significance. The DFIG can be characterized as a multi-state system (MSS) whose components have more than two states. However, due to the limited data and/or vague judgments from experts, it is difficult to obtain the accurate values of the states and thus it inevitably contains epistemic uncertainty. In this paper, the fuzzy universal generating function (FUGF) method is utilized to conduct the reliability assessment of the DFIG by describing the states using fuzzy numbers. First, the fuzzy states of the DFIG system’s components are defined and the entire system state is calculated based the system structure function. Second, all components’ states are determined as triangular fuzzy numbers (TFN) according to experts’ experiences. Finally, the reliability assessment of the DFIG based on the FUGF is conducted.

4

Optimal allocation of the electrical structure design using the bats approach

Chaker Abdelkader, Benaissa Abdelkader, Zablah Abdelkader, Belfedhal Alaa Eddine

Przegląd Elektrotechniczny

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2020

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R. 96, nr 6

98--102

EN

In this paper we describe and use a meta-heuristic optimization method is the algorithm of bats to be able to solve the problem of optimizing redundancy. This problem is known because we will strive to reduce the investment cost of the serial-parallel power system configuration through the algorithm, not to mention to maximize reliability and this is one of the constraints. Redundant components are included to achieve the desired level of availability, and service continuity. The maintainability of the system is based on a multi-state availability function. The elements of the power system are characterized by their performance, reliability, and availability and cost. These elements are chosen from a list of products available on the market. The meta-heuristic proposed seeks the best solution for a better configuration for our structure, which composes the system to be able to minimize the cost with the desired maximum reliability. To estimate the availability of the serial-parallel power system, a fast method based on the universal moment generation (UMGF) function is suggested. The algorithm approach of bats is used as an optimization technique. One gives an example of a power supply system for present simulation

PL

Opisano I zastosowano meta heurystyczną metodę optymalizacji problemu redundancji. Optymalizacja ma na celu redukcję kosztów szeregowo-równoległego systemu dystrybucyjnego. Elementy systemu były opisywane przez ich właściwości, niezawodność i dostępność.

5

A simulation approach on reliability assessment of complex system subject to stochastic degradation and random shock

Pourhassan Mohammad Reza, Raissi Sadigh, Hafezalkotob Ashkan

Eksploatacja i Niezawodność

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2020

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Vol. 22, no. 2

370--379

EN

Many systems are affected by different random factors and stochastic processes, significantly complicating their reliability analysis. In general, the performance of complicated systems may gradually, suddenly, or continuously be downgraded over times from perfect functioning to breakdown states or may be affected by unexpected shocks. In the literature, analytic reliability assessment examined for especial cases is restricted to applying the Exponential, Gamma, compound Poisson, and Wiener degradation processes. Consideration of the effect of non-fatal soft shock makes such assessment more challenging which has remained a research gap for general degraded stochastic processes. Through the current article, for preventing complexity of analytic calculations, we have focused on applying a simulating approach for generalization. The proposed model embeds both the stochastic degradation process as well randomly occurred shocks for two states, multi-state, and continuous degradation. Here, the user can arbitrarily set the time to failure distribution, stochastic degradation, and time to occurrence shock density function as well its severity. In order to present the validity and applicability, two case studies in a sugar plant alongside an example derived from the literature are examined. In the first case study, the simulation overestimated the system reliability by less than 5%. Also, the comparison revealed no significant difference between the analytic and the simulation result in an example taken from an article. Finally, the reliability of a complicated crystallizer system embedding both degradation and soft shock occurrence was examined in a threecomponent standby system.

PL

Prawidłowe działanie wielu systemów zależy od różnych czynników losowych i procesów stochastycznych, co znacznie komplikuje analizę niezawodności tych układów. Parametry pracy skomplikowanych systemów mogą ulegać stopniowemu, nagłemu lub stałemu obniżeniu ze stanu doskonałego funkcjonowania do stanu awaryjnego. Wpływ na nie mogą też mieć niespodziewane obciążenia. W literaturze przedmiotu, analityczną ocenę niezawodności stosuje się do badania przypadków szczególnych i ogranicza do badania degradacji w oparciu o proces wykładniczy, proces gamma, złożony proces Poissona i proces Wienera. Ocena niezawodności z uwzględnieniem wpływu obciążeń miękkich, nieprowadzących do całkowitej awarii, stanowi większe wyzwanie tworząc lukę w badaniach nad ogólnymi stochastycznymi procesami degradacji. Aby uniknąć złożonych obliczeń analitycznych, w niniejszej pracy skupiliśmy się na zastosowaniu podejścia symulacyjnego w celu uzyskania generalizacji. Proponowany model obejmuje zarówno stochastyczny proces degradacji, jak i losowo występujące obciążenia i uwzględnia przypadki degradacji systemów dwustanowych, wielostanowych oraz degradacji ciągłej. Posługując się tym modelem, użytkownik może dowolnie ustawiać rozkład czasu do uszkodzenia, degradację stochastyczną, czas do wystąpienia obciążenia, funkcję gęstości prawdopodobieństwa wystąpienia obciążenia, a także jego nasilenie. Trafność oraz możliwości zastosowania przedstawionego modelu zilustrowano na podstawie dwóch studiów przypadków dotyczących cukrowni oraz przykładu zaczerpniętego z literatury. W pierwszym studium przypadku, poziom niezawodności systemu obliczony na podstawie symulacji różnił się o mniej niż 5% od wyniku otrzymanego na drodze analitycznej. Porównanie nie ujawniło również żadnej istotnej różnicy między wynikiem analitycznym a symulacyjnym w przykładzie pochodzącym z literatury. Artykuł wieńczy analiza niezawodności złożonego układu krystalizatora, obejmująca zarówno degradację, jak i występowanie miękkich obciążeń w trójelementowym systemie krystalizatora z rezerwą.

6

Application of multistate systems safety modelling in maritime transport

Kołowrocki K., Soszyńska-Budny J.

Zeszyty Naukowe Akademii Morskiej w Szczecinie

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2016

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nr 45 (117)

114--119

EN

Basic concepts of the safety analysis of ageing multistate systems are introduced. The system components and the system multistate safety functions are defined. The mean values and variances of the multistate systems’ lifespans in the safety state subsets and the mean values of their lifespans in the particular safety states are defined. The multistate system risk function and the moment of exceeding the critical safety state are introduced. A series safety structure and a parallel-series safety structure of the multistate systems with ageing components are defined and their safety functions are determined. The multistate system safety models are applied to the prediction of safety characteristics of a maritime ferry.

7

A combined method for reliability analysis of multi-state system of minor-repairable components

Qin J., Niu Y., Li Z.

Eksploatacja i Niezawodność

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2016

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Vol. 18, no. 1

80--88

EN

This paper discusses the multi-state system (MSS) consisted of multi-state components with minor failure and minor repair. In order to obtain the reliability indices of MSS, a new combined method is suggested. This method is based on the Markov stochastic process and the universal generating function (UGF) technology. The traditional idea of modeling the MSS is to use straightforward Markov process. That is not effective enough for the MSS because the model of the system is complicated usually and the state space often arouses “dimension curse” - huge numbers of the states. We suggest it should model the multi-state components and the UGF of multi-state components can be obtained firstly. Then the MSS can be decomposed into several subsystems which only contain simple series-parallel structure. According to the physical nature of the subsystems, the UGF of those subsystems can be employed recursively. Furthermore the UGF of the entire MSS will be obtained. Therefore, the reliability indices of the MSS can be evaluated easily. The suggested method simplifies greatly the complexity of calculation and is well formulized. Two numerical examples illustrate this method.

PL

W artykule omówiono system wielostanowy (multi-state system, MSS) składający się z elementów wielostanowych, które mogą ulegać drobnym uszkodzeniom i podlegają drobnym naprawom. Zaproponowano nową metodę łączoną, która pozwala wyznaczać wskaźniki niezawodności MSS. Metoda ta opiera się na procesie stochastycznym Markowa oraz technologii uniwersalnej funkcji tworzącej (universal generating function, UGF). Tradycyjnie do modelowania MSS wykorzystuje się sam proces Markowa. Metoda ta nie jest jednak wystarczająco skuteczna w przypadku MSS, ponieważ modele tego typu systemów są zazwyczaj skomplikowane, a przestrzeń stanów często prowadzi do tzw. "przekleństwa wielowymiarowości" – konieczności uwzględnienia ogromnej liczby stanów. Nasza metoda polega na modelowaniu elementów wielostanowych, dla których, w pierwszej kolejności wyznacza się UGF. Następnie MSS można rozłożyć na kilka podsystemów, które mają prostą strukturę szeregowo-równoległą. Charakter fizyczny tych podsystemów, pozwala na rekurencyjne stosowanie UGF dla tych podsystemów. Ponadto metoda umożliwia wyznaczenie UGF dla całego MSS, co pozwala na łatwą ocenę wskaźników niezawodności MSS. Proponowana metoda znacznie upraszcza obliczenia i jest dobrze sformalizowana. W pracy przedstawiono dwa przykłady numeryczne, które ilustrują omawianą metodę.

8

Application of critical infrastructure safety modelling in port transport

Kołowrocki K., Soszyńska-Budny J.

Zeszyty Naukowe Akademii Morskiej w Szczecinie

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2015

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nr 44 (116)

128--134

EN

A new approach is proposed for safety investigations of complex multistate systems. These systems have dependent components, called critical infrastructures, with variable operating conditions. The safety function of the critical infrastructure system is defined and determined for an exemplary “m out of l” critical infrastructure. In the fully-developed model, it is assumed that system components have multistate exponential safety functions with interdependent departure rates from subsets of safety states. A critical infrastructure safety model is adopted for an oil pipeline transportation system operating in a maritime port.

9

A Markov model of a complex technical system operating in basic and emergency modes

Malinowski J.

Journal of Polish Safety and Reliability Association

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2015

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Vol. 6, No. 2

89--96

EN

A complex technical system built of independent repairable components with constant failure and repair rates is examined. The system can operate in either basic or emergency mode, and its behavior is modeled by a three-state Markov process. It is demonstrated how to obtain closed formulas for the state probabilities of this process and the so-called importances of individual components to the inter-state transitions. Such an importance is defined as the probability that a component’s failure/repair causes a transition between two given states of the modeling process. The obtained formulas allow to compute a number of reliability parameters characterizing the dynamics of the system’s operation. The obtained results are illustrated by their application to an exemplary reliability block diagram that can be a model of a power supply network, a gas or oil pipeline system, etc.

10

Reliability analysis of complex shipyard transportation system with dependent components

Blokus-Roszkowska A., Kołowrocki K.

Journal of Polish Safety and Reliability Association

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2014

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Vol. 5, No. 1

21--32

EN

In the paper an approach to the reliability analysis of multi-state systems with dependent components operating at variable operation conditions is presented. The multi-state reliability function of complex system is defined and determined for the shipyard rope ship elevator. In developed models, it is assumed that system components have the multi-state exponential reliability functions with interdependent departures rates from the subsets of reliability states.

11

Preliminary reliability, risk and availability analysis and evaluation of bulk cargo transportation system in variable operation conditions

Kołowrocki K., Kwiatuszewska-Sarnecka B., Soszyńska J.

Journal of Polish Safety and Reliability Association

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2009

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Vol. 1

179--188

EN

In the paper, definitions and theoretical results on system operations process, multi-state system reliability, risk and availability modelling are illustrated by the example of their application to a bulk cargo transportation system operating in Gdynia Port Bulk Cargo Terminal. The bulk cargo transportation system is considered in varying in time operation conditions. The system reliability structure and its components reliability functions are changing in variable operation conditions. The system reliability structures are fixed with a high accuracy. Whereas, the input reliability characteristics of the bulk cargo transportation system components and the system operation process characteristics are not sufficiently exact because of the lack of statistical data. Anyway, the obtained evaluation may be a very useful example in simple and quick systems reliability characteristics evaluation, especially during the design and improving the transportation systems operating in ports.

12

Ant Colony Optimization for Electrical Power System Expansion-Scheduling

Hadjeri S., Zeblah A.

Przegląd Elektrotechniczny

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2008

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R. 84, nr 7

36-42

EN

This paper uses an ant colony meta-heuristic optimization method to solve the multi-stage expansion problem for multi-state series-parallel systems. The study horizon is divided into several periods. At each period the demand distribution is forecasted in the form of a cumulative demand curve. A multiple-choice of additional components among a list of available product can be chosen and included into any subsystem component at any stage to improve the system performance. The components are characterized by their cost, performance (capacity) and availability. The objective is to minimize the whole investment-costs over the study period while satisfying availability or performance constraints. A universal generating function technique is applied to evaluate system availability. The ant colony approach is required to identify the optimal combination of adding components with different parameters to be allocated in parallel at each stage.

PL

W artykule omówiono metodę optymalizacji wykorzystującą algorytmy mrówkowe. Rozwiązywano problem wielopoziomowej rozbudowy szeregowo-równoległego system zasilania. Horyzont czasowy analizy został podzielony na mniejsze okresy. W każdym okresie potrzeby są prognozowane w postaci kumulacyjnej krzywej potrzeb. Różny wybór dodatkowych składowych systemu był możliwy na każdym etapie analizy. Te składowe były charakteryzowane przez koszt, możliwości i parametry. Celem była minimalizacja całkowitych kosztów inwestycji przy wymuszonych parametrach. Algorytm mrówkowy został wykorzystany do optymalizacji systemu na każdym etapie dodawania nowego elementu.

13

Decomposition and estimation of multi-state systems by dynamic reliability indices

Zaitseva E., Levashenko V., Matiaško K.

Journal of KONBiN

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2008

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No. 1 (4)

353-361

EN

Some typical configurations of Multi-State System and their mathematical descriptions are considered in paper with relation to Reliability Analysis. Multiple-Valued Logic is applied for these descriptions synthesis and Dynamic Reliability Indices are used for Multi-State System reliability estimation. We concentrate on series and parallel systems, because these structures are basic for most of the technical system. We get measures of reliability for the failure and restoration of this system.

14

Reliability analysis of multi-state ageing consecutive „k out of n: F” systems

Guze S., Kołowrocki K.

Journal of Polish Safety and Reliability Association

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2007

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Vol. 1

173--180

EN

A multi-state approach to reliability analysis of systems composed of ageing components is introduced and basic reliability characteristics for such systems are defined. Further, a multi-state consecutive “ k out of n : F” system composed of ageing components is defined and the recurrent formulae for its reliability function are proposed. Moreover, the application of the proposed reliability characteristics and formulae to reliability evaluation of the steel cover composed of ageing sheets is illustrated.

15

On multi-state safety analysis in shipping

Dziula P., Jurdziński M., Kołowrocki K., Soszyńska J.

Journal of Polish Safety and Reliability Association

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2007

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Vol. 1

83--96

EN

A multi-state approach to defining basic notions of the system safety analysis is proposed. A system safety function and a system risk function are defined. A basic safety structure of a multi-state series system of components with degrading safety states is defined. For this system the multi-state safety function is determined. The proposed approach is applied to the evaluation of a safety function, a risk function and other safety characteristics of a ship system composed of a number of subsystems having an essential influence on the ship safety. Further, a semi-Markov process for the considered system operation modelling is applied. The paper also offers a general approach to the solution of a practically important problem of linking the multi-state system safety model and its operation process model. Finally, the proposed general approach is applied to the preliminary evaluation of a safety function, a risk function and other safety characteristics of a ship system with varying in time its structure and safety characteristics of the subsystems it is composed of.

16

Failure analysis of series and parallel multi-state system

Zaitseva E., Levashenko V., Matiaško K.

Eksploatacja i Niezawodność

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2006

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nr 2

29-32

EN

The reliability of the Multi-State System is investigated by Dynamic Reliability Indices in this paper. These indices estimate influence upon the Multi-State System reliability by the state of a system component. Structure function and mathematical tools of Multiple-Valued Logic calculate them. Dynamic Reliability Indices for failure of parallel and series systems are examined in detail.