Tom Ruxton

A fuzzy-logic-based approach to qualitative safety modelling for marine systems

Abstract Safety assessment based on conventional tools (e.g. probability risk assessment (PRA)) may not be well suited for dealing with systems having a high level of uncertainty, particularly in the feasibility and concept design stages of a maritime or offshore system. By contrast, a safety model using fuzzy logic approach employing fuzzy IF–THEN rules can model the qualitative aspects of human knowledge and reasoning processes without employing precise quantitative analyses. A fuzzy-logic-based approach may be more appropriately used to carry out risk analysis in the initial design stages. This provides a tool for working directly with the linguistic terms commonly used in carrying out safety assessment. This research focuses on the development and representation of linguistic variables to model risk levels subjectively. These variables are then quantified using fuzzy sets. In this paper, the development of a safety model using fuzzy logic approach for modelling various design variables for maritime and offshore safety based decision making in the concept design stage is presented. An example is used to illustrate the proposed approach.

Novel risk assessment techniques for maritime safety management system

Following a brief review of the current status of offshore safety regulations in the UK, several issues pertaining to the problems encountered in applying the existing reliability and safety analysis methods in quantitative safety appraisal studies, especially in the early concept design stage of maritime engineering products, are discussed. Presents three novel risk assessment and decision support frameworks. These include a design trade‐off approach using Taguchi method, a safety based decision support system based on artificial neural network techniques, and a fuzzy‐logic‐based synthesis incorporating the Dempster‐Shafer approach for making multiple attribute decision. Three illustrative examples are used to demonstrate the novel tools, together with the discussion on the conditions under which each approach may be applied effectively. Finally, recommendations on further development in safety modelling, decision‐making techniques and their integration into safety management systems, are suggested.

Use of fuzzy logic approaches to safety assessment in maritime engineering applications

Safety assessment based on conventional methods such as probability risk assessment (PRA) may not be well suited for dealing with innovative systems having a high level of uncertainty, particularly in the feasibility and concept design stages of a maritime engineering system. By contrast, safety models using fuzzy logic approaches employing fuzzy IF-THEN rules can model the qualitative aspects of human knowledge and reasoning processes without employing precise quantitative analyses. Fuzzy-logic-based approaches may be more appropriately used to carry out risk analysis in the initial design stages of large maritime engineering systems. This provides a tool for working directly with the linguistic terms commonly used in carrying out safety assessment. This paper focuses on the development and representation of linguistic variables to model risk levels subjectively. These variables are then quantified using fuzzy set theory. In this paper, the development of two safety evaluation frameworks using fuzzy logic approaches for maritime engineering safety-based decision support in the concept design stage are presented. An example is used to illustrate and compare the proposed approaches. Future risk analysis in maritime engineering applications may take full advantages of fuzzy logic approaches to complement existing ones.

A Fuzzy-Logic-Based Approach to Subjective Safety Modelling for Maritime Products

ABSTRACT Safety assessment based on conventional tools (e.g., probability risk assessment (PRA)) may not be well suited for dealing with systems having a high level of uncertainty, particularly in the feasibility and concept design stages of a maritime or offshore system. By contrast, a safety model using fuzzy logic approach employing fuzzy IF-THEN rules can model the qualitative aspects of human knowledge and reasoning processes without employing precise quantitative analyses. A fuzzy-logic-based approach may be more appropriately used to carry out risk analysis in the initial design stages. This provides a tool for working directly with the linguistic terms commonly used in carrying out safety assessment. This paper focuses on the development and representation of linguistic variables to model risk levels subjectively. These variables are then quantified using fuzzy sets. In this paper, the development of a safety model using fuzzy logic approach for modelling various design variables for maritime and offshore safety based Decision making in the concept design stage is presented. An example is used to illustrate the proposed approach.

Marine and Offshore Safety Assessment

Abstract This brief communication serves to introduce a marine and offshore safety assessment research project, which has been carried out at both Staffordshire and Liverpool John Moores Universities.

A statistical review of the risk associated with offshore support vessel/platform encounters in UK waters

Safety performance on the UK Continental Shelf is normally considered to be of a high standard, although there are still many incidents and accidents. This paper discusses some of the initial findings in an offshore support vessel safety research project. Following a brief review study of the uses of various types of existing offshore support vessels, a comprehensive statistical failure data analysis of the vessels is carried out mainly based on a Ship/Platform Incident Database drawn from the Health and Safety Executive (HSE). The variation of incident frequency with time for different types of offshore oil and gas installations, and for different vessel types has been established. A total of 394 records within the period 1980 to 1997 are investigated in this study. The variation of incident frequency with time and seasons, causation factors, incident with respect to geographical distribution, and sea conditions are discussed. The relationship between vessel types, sizes and operations is analysed; operating circumstances, reported primary failure cause, and impart orientation for different vessel types are also described. The statistical analysis reveals that safety culture in terms of good seamanship by vessel masters is probably responsible for mitigating the magnitude of many of the impacts that do occur and also that there is a need for improvement in safety performance. Issues pertaining to human element, the availability and reliability of data, risk criteria, and safety culture in the context of marine and offshore risk assessment are also discussed.

Novel risk assessment and decision support techniques for safety management systems

A brief review of the current status of marine and offshore safety regulations in the UK is outlined. Several issues pertaining to the problems encountered in applying the existing reliability and safety analysis methods in quantitative safety appraisal studies, especially in the early concept design stage of marine and offshore engineering products, are discussed. In this paper, four novel risk assessment and decision support frameworks are presented. These include a design trade-off approach using the Taguchi method, a safety-based decision support system based on artificial neural network techniques, a fuzzy-logic-based synthesis incorporating the Dempster-Shafer approach for multiple attribute decision-making, and an integration of approximate reasoning approach and evidential reasoning method for design evaluation. Four illustrative examples are used to demonstrate the novel tools, together with the discussion on the conditions under which each approach may be applied effectively. Finally, recommendations on further development in subjective safety modelling, decisionmaking techniques and their integration into a safety management system are suggested.

An Experimental Investigation of NOx Emission Reduction From Automotive Engine Using the Miller Cycle

An experimental investigation of NOx emission reduction from automotive (petrol) engine using the Miller Cycle was carried out. Two versions of Miller Cycle were designed and realized on a petrol engine. The tests were carried out on the test rig. The test results showed that applying Miller Cycle could reduce the emission of nitrogen oxides from petrol engine.Copyright