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1

Reliability estimation of a Network Structure using Generalized Trapezoidal Fuzzy Numbers

Kumar Amit, Dhiman Pooja

Journal of KONBiN

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2021

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Vol. 51, iss. 1

225--241

EN

Classical sets are used commonly to consider reliability. Because of the uncertainty in the data (which considered in the present paper) classical sets fail to describe the reliability accurately. Uncertainty leads to fluctuation in the actual situation of the structure. Fuzzy logic method attempts to test system reliability with the benefit of membership function. Within this context, specific problems of reasoning-based approaches are studied, explored and correlated with standard reliability approaches. In this paper Generalized Trapezoidal Fuzzy numbers (GTrFN) are used to assess the structure's fuzzy reliability. The reliability of each event is assigned with different level of satisfaction and some improved operations on the generalized trapezoidal fuzzy numbers (GTrFN) are used to calculate the fuzzy boundaries for the resultant reliability of the final event along with the degree of satisfaction. Also the results are compared to demonstrate the application of the improved operations on Generalized Trapezoidal Fuzzy Numbers (GTrFN). The obtained results converge to more precise interval values as compare to the vague fuzzy number.

2

A fault tree-based approach for aviation risk analysis considering mental workload overload

Che Haiyang, Zeng Shengkui, You Qidong, Song Yueheng, Guo Jianbin

Eksploatacja i Niezawodność

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2021

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Vol. 23, no. 4

646--658

EN

Many lives and aircrafts have been lost due to human errors associated with mental workload overload (MWLOL). Human errors are successfully considered in existing Fault Tree Analysis (FTA) methods. However, MWLOL is considered through Performance Shaping Factors indirectly and its information is hidden in FT construction, which is not conducive to analyze the root causes of human errors and risks. To overcome this difficulty, we develop a risk analysis method where Multiple Resources Model (MRM) is incorporated into FTA methods. MRM analyzes mental workload by estimating the resources used during performing concurrent tasks, probably including abnormal situation handling tasks introduced by basic events in FT. Such basic events may cause MWLOL and then trigger corresponding human error events. A MWLOL gate is proposed to describe MWLOL explicitly and add these new relationships to traditional FT. This new method extends previous FTA methods and provides a more in-depth risk analysis. An accident, a helicopter crash in Maryland, is analyzed by the proposed method.

3

Hierarchical state machine model for analyzing safety hazards in real-time systems

Bakr Ahmed M., Salama May, Alsammak Abdelwahab K.

Computer Science

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2021

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T. 22 (1)

39-80

EN

Real-time systems must avoid hazardous situations. To achieve this, their functionality should be investigated under time constraints. A model based on Hierarchical Communicating Real-time State Machine (H-CRSM) and analysis methodology is proposed in this paper with the objective of obtaining any hazardous events that may occur in the input ANSI-C program. The system outputs a scenario list of the different hazards. A path in the code showing the cause of the undesirable event is associated with each hazardous scenario. The strength of the proposed methodology is that the process of hazardous situation detection does not require the running of the ANSI-C program many times with distinct values for the inputs. It also focuses on analyzing the software level of the life cycle. It is not like most of the verification and analysis tools that check system levels. The system level may be bug-free, but the software level may not be.

4

The analysis of transformer's condition based on Bayes-discriminant method with fault-tree fuzzy evaluation

Li Dianyang, Wang Shanyuan, Zhang Yujie, Feng Jian, Wang Hongzhe, Qin Ling

Diagnostyka

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2020

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Vol. 21, No. 2

3--12

EN

China's electric power construction is renewing Increasingly, and the network is complex and changeable where the automation is getting higher. In this paper, Fuzzy evaluation system is established according to fault tree, and the estimation of transformer’s state is judged by analytic hierarchy process. Bayes-discriminant and discriminant formula are used to discriminate transformer’s attributes, which are based on historical data. The machine identification of transformer faults combines the fuzzy evaluation and Bayes-discriminant. It’s accuracy can be improved by correcting parameters. This method can effectively avoid subjective interference caused by artificial weights. The example shows that this method could be applied to judge health status of electric power equipment and this method can play an early-warning role in the operation of monitoring system.

5

Zastosowanie metody FTA do identyfikacji zagrożeń występujących podczas pracy urządzeń transportu podziemnego

Ignac-Nowicka J.

Systemy Wspomagania w Inżynierii Produkcji

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2018

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Vol. 7, iss. 1

209--217

PL

Urządzenia transportu podziemnego ze względu na pracę w ograniczonych przestrzeniach wyrobisk górniczych niosą specyficzne zagrożenia dla pracującej załogi. W artykule przeanalizowano pracę maszyn transportowych takich jak: taśmociągi, kolej szynowa oraz transport pionowy w szybach górniczych. Do analizy zagrożeń wykorzystano metodę drzewa błędów wyznaczając bezpośrednie i pośrednie przyczyny zagrożeń w transporcie podziemnym. Konstrukcję drzewa błędów przedstawiono dla trzech rodzajów zdarzeń: transport taśmociągiem, kolejką szynową oraz transport pionowy szybem kopalnianym.

EN

Underground transport equipment due to work in limited spaces of mining excavations carry specific hazards to the working crew. The article analyzes the operation of transport machines such as conveyor belts, underground railway and vertical transport in mining shafts. The fault tree method was used to analyze the hazards by determining the direct and indirect causes of hazards in underground transport. The construction of the fault tree was presented for three types of events: transport by conveyor, underground railway and vertical transport by a mine shaft.

6

Fault Tree Analysis as a Tool to Increase the Level of Security in an Enterprise

Ignac-Nowicka J., Krenický T.

Multidisciplinary Aspects of Production Engineering

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2018

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Vol. 1, Iss. 1

719--725

EN

Technological progress, as well as the development of the sciences on occupational health and safety, increased safety and improved working conditions in enterprises of even the most onerous industries. To maintain the required level of safety, preventive actions are taken to identify all hazards in the workplace. In practice, many methods are used to identify hazards depending on the type of technological processes and the types of workstations analyzed. The article presents the advantages of the fault tree analysis method as a tool to support the process safety management in the enterprise. The article presents features of the fault tree analysis method as a tool for better security management in an enterprise. Cause and effect relationships between events in the fault tree schema on selected examples were examined. Indirect and direct causes of accidents and failures in the enterprise have been identified, including human errors (human factor). The use of the fault tree analysis method to support accident and failure risk assessment in an industrial plant was also analyzed.

7

System reliability optimisation of Cooling-cum-Condensate-Extraction system

Biswal G. R.

Eksploatacja i Niezawodność

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2016

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Vol. 18, no. 1

117--122

EN

A novel methodology is presented for condensation in power generation plants; this section is the main intersection of heat loss, typically 40% thermal efficiency of a plant. Condensate section is interfaced with the generating section to enhance the active contribution of the system. Both the cooling section and the condensate section are integrated and interfaced through the low-pressure and high-pressure cycles to attain the improved electrical efficiency, which affects the heat transfer capability of the power generation plants. This paper proposess a Cooling-cum-Condensate-Extraction System (CCES), to dedicate a 36-MW- captive power plant. The paper is dedicated for the design and development of an effective CCES, analyzing its impact over the systems in terms of system reliability optimization, and the role of real-time optimization. The designed model also contributes in discharging lesser amount of flu gases as against existing technologies with its improved active operation hours.

PL

W artykule przedstawiono nowatorską metodologię procesu skraplania do zastosowania w części kondensacyjnej elektrowni, gdzie dochodzi do największych strat ciepła – przeważnie aż 40% wydajności termicznej elektrowni. W proponowanym rozwiązaniu instalację kondensacyjną sprzężono z częścią prądotwórczą aby zwiększyć aktywny wkład systemu. Część chłodzącą zintegrowano i sprzężono z częścią kondensacyjną poprzez cykle nisko- i wysokociśnieniowe, uzyskując w ten sposób lepszą wydajność elektryczną, co ma wpływ na zdolność wymiany ciepła w elektrowni. W artykule przedstawiono układ chłodzenia z systemem odprowadzania skroplin (CCES) przeznaczony dla elektrowni potrzeb własnych o mocy 36 MW. Pracę poświęcono projektowaniu i konstrukcji efektywnego CCES, analizując jego wpływ na systemy elektrowni w zakresie optymalizacji niezawodności systemów oraz roli optymalizacji w czasie rzeczywistym. Zaprojektowany przez nas model, w porównaniu z istniejącymi technologiami, przyczynia się również do zmniejszenia emisji gazów odlotowych dzięki zoptymalizowanemu czasowi pracy.

8

Analysis of risk and failure scenarios in water supply system

Boryczko K., Rak J., Tchórzewska-Cieślak B.

Journal of Polish Safety and Reliability Association

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2014

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Vol. 5, No. 2

11--18

EN

Water supply system is complicated technical system which belongs to underground urban infrastructure. Its accurate functioning determines everyday live stability of citizens. Risk analysis is a key phase of the process of water supply safety management. The aim of this paper is to present new propose of methods for risk of the first type (associated with quantity of supplied water) and the risk of the second type (associated with quality of supplied water) analyses in water supply system. The paper contains the description of matrix methods for risk analyses and methods describing cause-and-effect relationship of failure events (fault tree analysis).

9

Fundamentals of the Dempster-Shafer theory and its applications to system safety and reliability modelling

Rakowsky U. K.

Journal of Polish Safety and Reliability Association

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2007

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Vol. 2

283--295

EN

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.