STABILITY FAILURE ANALYSIS IN THE OPERATIONS OF FLOATING DRY DOCKS

2021 ◽  
Vol 159 (A1) ◽  
Author(s):  
D A Njumo
Keyword(s):  
Failure Analysis ◽  
Set Theory ◽  
Fuzzy Set ◽  
Fuzzy Set Theory ◽  
Evidential Reasoning ◽  
Linguistic Variables ◽  
Main Area ◽  
Failure Data ◽  
Dry Dock

The main area of this work reflects a topic for which there is little or limited reference available and is carried out to meet the needs of professional and practical floating dry dock operators. The risk of hazards in floating dry docks is evaluated using a discrete fuzzy set theory (FST) and an evidential reasoning (ER) approach in a situation where historical failure data is not available. Fuzzy set modelling is used to estimate the safety levels of the causes of basic failure events in floating dry docks due to stability concerns using the concept of linguistic variables, and provides a framework for dealing with such variables in a systematic way. The ER approach is used to synthesise the estimated safety levels of the causes of hazards/basic hazard events. The results of this work will be valuable to dry dock masters and sister maritime engineering professionals.

Stability Failure Analysis in the Operations of Floating Dry Docks

2017 ◽  
Vol Vol 159 (A1) ◽  
Author(s):  
D A Njumo
Keyword(s):  
Failure Analysis ◽  
Set Theory ◽  
Fuzzy Set ◽  
Fuzzy Set Theory ◽  
Evidential Reasoning ◽  
Linguistic Variables ◽  
Main Area ◽  
Failure Data ◽  
Dry Dock

The main area of this work reflects a topic for which there is little or limited reference available and is carried out to meet the needs of professional and practical floating dry dock operators. The risk of hazards in floating dry docks is evaluated using a discrete fuzzy set theory (FST) and an evidential reasoning (ER) approach in a situation where historical failure data is not available. Fuzzy set modelling is used to estimate the safety levels of the causes of basic failure events in floating dry docks due to stability concerns using the concept of linguistic variables, and provides a framework for dealing with such variables in a systematic way. The ER approach is used to synthesise the estimated safety levels of the causes of hazards/basic hazard events. The results of this work will be valuable to dry dock masters and sister maritime engineering professionals.

scholarly journals Application of Fuzzy DEMATEL in Risks Evaluation of Knowledge-Based Networks

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
M. Abbasi ◽  
R. Hosnavi ◽  
B. Tabrizi
Keyword(s):  
Risk Factors ◽  
Set Theory ◽  
Fuzzy Set ◽  
Fuzzy Set Theory ◽  
New Products ◽  
Linguistic Variables ◽  
Fuzzy Dematel ◽  
Knowledge Based ◽  
Wide Range ◽  
Do So

Developing new products has received much attention within the last decades. This issue can be highlighted for strategic innovations, in particular. Recently, knowledge-based networks have been introduced in order to facilitate the affair of transforming knowledge into commercial products which can be regarded as a set of research centers, universities, knowledge intermediaries, customers, and so forth. However, there is a wide range of risk factors that are liable to affect the chain performance. Hence, this paper aims to consider the most influencing criteria that can play a more significant role in achievements of such networks. To do so, DEMATEL has been applied to take the relationships between the risk factors into account. Moreover, fuzzy set theory has been utilized in order to deal with the linguistic variables. Finally, the most important factors are identified and their relations are determined.

scholarly journals Research on a Safety Assessment Method for Leakage in a Heavy Oil Gathering Pipeline

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1340
Author(s):  
Peng Zhang ◽  
Xiangsu Chen ◽  
Chaohai Fan
Keyword(s):  
Set Theory ◽  
Fuzzy Set ◽  
Failure Probability ◽  
Heavy Oil ◽  
Fuzzy Set Theory ◽  
Information Diffusion ◽  
Safety Assessment ◽  
Assessment System ◽  
Failure Data ◽  
Pipeline Failure

At present, the number of oil and gas gathering and transportation pipelines is numerous, and leakage accidents occur frequently. Each year, due to pipeline failure, there are immeasurable consequences for people and the environment around the affected pipelines. In order to reduce the risk of leakage accidents in heavy oil gathering pipelines and prevent the occurrence of major spills, it is of great significance to carry out safety assessments of them. However, failure data of these pipelines is seriously deficient and statistical methods used to evaluate pipeline safety are incompatible. Therefore, this paper proposes a risk assessment system for heavy oil gathering pipelines in the absence of failure data. Firstly, a Bayesian network (BN) for the leak safety evaluation of heavy oil gathering pipelines is established via mapping from a bow-tie (BT) model. Then, information diffusion theory is combined with fuzzy set theory to obtain the failure probability of each factor affecting the pipeline failure, and then the failure probability of the pipeline is obtained by the full probability formula. In addition, in order to assess the extent of consequences due to accidents, variable fuzzy set theory is used to comprehensively consider the consequences of the leakage of heavy oil gathering pipelines. Finally, the above two parts are combined to form a safety assessment system to realize risk management and control for pipelines, which is necessary to ensure the safety of heavy oil gathering pipelines.

Developing environmental indices based on fuzzy set theory and evidential reasoning

2011 ◽  
Author(s):  
Ya Juan Zhang ◽  
Xin Yang Deng ◽  
Bing Yi Kang ◽  
Ji Yi Wu ◽  
Xiao Hong Sun ◽  
...  
Keyword(s):  
Set Theory ◽  
Fuzzy Set ◽  
Fuzzy Set Theory ◽  
Evidential Reasoning ◽  
Environmental Indices

PREVENTIVE MAINTENANCE SCHEDULING FOR A SYSTEM WITH ASSURED RELIABILITY USING FUZZY SET THEORY

1994 ◽  
Vol 01 (04) ◽  
pp. 497-513 ◽  
Author(s):  
P.V. SURESH ◽  
DIPAK CHAUDHURI
Keyword(s):  
Fuzzy Sets ◽  
Set Theory ◽  
Fuzzy Set ◽  
Fuzzy Set Theory ◽  
Preventive Maintenance ◽  
Operating Conditions ◽  
Maintenance Scheduling ◽  
Linguistic Variables ◽  
Operating Condition ◽  
Starting Condition

Preventive maintenance of any system should depend on its starting, ending and operating conditions. Systems working with a minimum permissible reliability should be maintained at predetermined points to ensure its reliability do not fall below the permissible level. For any period, the starting condition of a system and the operating condition can be specified using fuzzy sets. Since the condition of the system at the end of a period depends on its starting condition and the operating condition during the period, linguistic variables are also required to specify it. This paper describes how to select periods of maintenance and the types of maintenance for such a system. The model utilizes the fuzzy set theory to determine the period length and the type of maintenance.

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