Multi-criteria decision making support tools for maintenance of marine machinery systems

PhD ThesisFor ship systems to remain reliable and safe they must be effectively maintained through a sound maintenance management system. The three major elements of maintenance management systems are; risk assessment, maintenance strategy selection and maintenance task interval determination. The implementation of these elements will generally determine the level of ship system safety and reliability. Reliability Centred Maintenance (RCM) is one method that can be used to optimise maintenance management systems. However the tools used within the framework of the RCM methodology have limitations which may compromise the efficiency of RCM in achieving the desired results. This research presents the development of tools to support the RCM methodology and improve its effectiveness in marine maintenance system applications. Each of the three elements of the maintenance management system has been considered in turn. With regard to risk assessment, two Multi-Criteria Decision Making techniques (MCDM); Vlsekriterijumska Optimizacija Ikompromisno Resenje, meaning: Multi-criteria Optimization and Compromise Solution (VIKOR) and Compromise Programming (CP) have been integrated into Failure Mode and Effects Analysis (FMEA) along with a novel averaging technique which allows the use of incomplete or imprecise failure data. Three hybrid MCDM techniques have then been compared for maintenance strategy selection; an integrated Delphi-Analytical Hierarchy Process (AHP) methodology, an integrated Delphi-AHP-PROMETHEE (Preference Ranking Organisation METHod for Enrichment Evaluation) methodology and an integrated Delphi-AHP-TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) methodology. Maintenance task interval determination has been implemented using a MCDM framework integrating a delay time model to determine the optimum inspection interval and using the age replacement model for the scheduled replacement tasks. A case study based on a marine Diesel engine has been developed with input from experts in the field to demonstrate the effectiveness of the proposed methodologies.Tertiary Education Trust Fund (TETFUND), a scholarship body of the Federal Republic of Nigeria for providing the fund for this research. My gratitude also goes to Federal University of Petroleum Resource, Effurun, Nigeria for giving me the opportunity to be a beneficiary of the scholarship

Machinery/service system Scheduled Replacement time determination: A combine Weighted Aggregated Sum Product Assessment, Additive Ratio Assessment and Age Replacement Model approach

The productivity of manufacturing/service industries greatly depend on the safety and reliability of the machinery/service system use for production/service delivery. The safety and reliability of the system can only be guaranteed through efficient maintenance. Scheduled replacement is an integral element of maintenance strategies. The major challenge of the maintenance policy is the determination of the optimum interval for carrying out replacement of equipment item of machinery/service system. A number of approaches have been applied in the literature in addressing this problem but these techniques have one limitation or another. In this paper, an MCDM approaches which avoid these limitations is proposed. The proposed Multi-Criteria Decision Making (MCDM) techniques combined weighted Aggregated Sum Product Assessment (WASPAS) and Additive Ratio Assessment (ARAS) with Age Replacement Model (ARM) for the determination optimum scheduled replacement time interval. The ARM for cost, reliability and downtime are aggregated using WASPAS and ARAS methods in order to rank alternative time intervals. The WASPAS and ARAS methods outputs are compared with another well-known technique in literature. To demonstrate the applicability of the proposed approaches a numerical example was applied. The result of the analysis revealed that, WASPAS and ARAS produces similar ranking for alternatives when compared with that of TOPSIS technique in the literature which is more computationally intensive, thereby validating the suitability of the proposed approaches

FAILURE MODE AND EFFECTS ANALYSIS OF SHIP SYSTEMS USING AN INTEGRATED DEMPSTER SHAFER THEORY AND ELECTRE METHOD

Failure Mode and Effects Analysis (FMEA) is a risk analysis tool which is used to define, identify, and eliminate known and/or potential failures from a system. The task is generally performed by team of experts. Each of the team of experts can express diverse opinions in rating of failure modes of systems which may be in the form of precise data and imprecise distribution ratings. However the RPN of FMEA is incapable of using these various forms of information in the prioritisation of risk of failure modes. This is one of the main limitations of FMEA. Furthermore the technique is limited to the use of three decision criteria thereby excluding other important decision criteria such as production loss in prioritising risk. To address these problems a novel FMEA tool is proposed which combines Dempster Shafer Theory with the ELECTRE method to provide a more efficient failure mode prioritisation method. With this technique the Dempster Shafer Theory is used in aggregating different failure mode ratings from experts and the ELECTRE method is applied in the ranking of failure modes. The applicability of the proposed technique is demonstrated with a case study of a marine diesel engine. Results showed that the proposed method can be applied in addressing risk prioritisation problem more efficiently than the FMEA and its variant

Fabrication and Assessment of a Motorcycle Piston using the Traditional Sand Casting Method

The RX 100 motorcycle piston was fabricated from end-of-life automobile piston using the traditional sand casting method. The fabricated piston was subjected to thermal analysis using ANSYS R18.1 version software to ascertain its performance under thermal loads. The recycled EOL aluminium used in the fabrication of the piston was characterised using SEM-EDS to determine the composition and morphology of the material. Results obtained show that the EOL aluminium employed in the fabrication of the piston performed excellently under thermal loads, and the SEM-EDS indicates that the material is predominantly aluminium with beneficial alloying elements

Fuzzy Cost Modelling of Diving Chamber Control Measures under Uncertainties

The diving chamber is an important system needed for diving operations in the oil and gas industry. Divers use it for various purposes. Thus, the safety level of the diving chamber needs to be very high at all times and the system needs to be in a good state. To achieve this, various control measures such as control measures 1 and 2 can be adopted in preventing failures/hazards or mitigate their consequences. In this study, fuzzy cost algorithm is used to estimate the cost of using control measures 1 and 2 in ensuring optimal operational level for the diving chamber, while the preference degree approach is adopted in prioritizing the aforementioned cost of control measures 1 and 2. The result of the analysis indicated that control measure 2 is the most cost effective approach

Prioritising Alternative Solutions to Power Generation Problems Using MCDM Techniques: Nigeria as Case Study

The engine that energizes industrialization and which invariably result to improved standard of living of nations’ citizens is electric power. Hence a steady power supply is crucial for Nigeria to achieve her aim of becoming one of the most industrialised nation in the world. However the biggest challenge in Nigeria is electricity crisis, a crisis that had been without any visible end in sight. From the literature the problems of power generation in Nigeria ranges from improper maintenance of power generation infrastructure to militant activities. Although alternative solutions are available for addressing these problems but there is difficulty in selecting the optimal solution that will yield greater power output. This paper present a Multi-Criteria Decision Making (MCDM) tool for prioritising alternatives solutions to power generation problems. The tool uses a combination of entropy technique and Multi-Attribute Utility Theory (MAUT) method. To illustrate the suitability of the technique, two examples were utilised. Results of the analysis revealed that Reliability Centered Maintenance (RCM) and diplomatic approach are the optimal solutions for resolving problem of improper maintenance and militant activities respectively. The proposed tool will assist Government or electric power managers to use optimal solutions in solving power generation problems in order to maximise power plant output and consistently ameliorate power crisis.Â

Facilitating Improvement of Design for Safety and Operations of a Seaweed Harvester: A Hybrid Traditional Safety Method

Sea harvester is a vital marine vessel needed in sea safety and cleanliness. Reliability and safety of the operations of the vessel need to be ensured via identification of hazards/failures that tends to affect the system and prevent them from occurring and also mitigate their consequences. In this research, a traditional hybrid methodology is employed in ensuring the reliability and safety of a sea harvester. The methodology is a logical combination of preliminary hazard analysis (PHA), risk matrix approach (RMA) and event tree analysis (ETA). Fire, flood, machinery failure and capsize that pose to affect optimal operations of a sea harvester are identified using a PHA method. RMA is incorporated in application of the PHA method to estimate the risks associated with them. Due the fact that risks associated with fire, flood, machinery failure and capsize are classified as very high, identifying preventing measures becomes necessary. Furthermore, systems which by means of their operability and non-operability can mitigate fire, flood, machinery failure, capsize and grounding consequences are captured using an ETA method. Therefore, the traditional hybrid methodology developed is successfully applied in design for safety, construction and operation of a sea harveste

Comparative Study of the use of Arithmetic Mean and Geometric Mean for Data Aggregation in FMEA Analysis

Failure Mode and Effects Analysis (FMEA) is a commonly use approach for ranking risk of failure modes of most marine machinery system. However, the Risk Priority Number (RPN) use for evaluating risk within FMEA framework have several limitations and as such most researchers focus had been in the area of improvement of the tool without considering the effect of the aggregated data from multiple experts use as input  into the decision making process. The purpose of this paper therefore, is to perform a comparative analysis of the aggregation techniques for combining multiple experts’ ratings of failure modes in order to establish their degree of similarity and their effect on the output of the ranking tools. The commonly used aggregation techniques in the literature considered are; Arithmetic Mean (AM) and Geometric Mean (GM). The index for comparison of the AM and GM was based on the effect of their respective aggregated data on the rank produced by four well known ranking tools; RPN of FMEA, Compromise Programming (CP), Vlsekriterijumska Optimizacija Ikompromisno Resenje, meaning: Multicriteria Optimization and Compromise Solution (VIKOR), Weighted Sum Model (WSM) and Weighted Product Model (WPM). A case study of fuel oil system of marine diesel engine of ship system was utilised to demonstrate the effectiveness of the two techniques

Elements of maintenance system and tools for implementation within framework of Reliability Centred Maintenance- A review

For plant systems to remain reliable and safe they must be effectively maintained through a sound maintenance management system. The three major elements of maintenance management systems are; risk assessment, maintenance strategy selection and maintenance task interval determination. The implementation of these elements will generally determine the level of plant system safety and reliability. Reliability Centred Maintenance (RCM) is one method that can be used to optimise maintenance management systems. This paper discusses the three major elements of a maintenance system, tools utilised within the framework of RCM for performing these tasks and some of the limitations of the various tools. Each of the three elements of the maintenance management system has been considered in turn. The information will equip maintenance practitioners with basic knowledge of tools for maintenance optimisation and stimulate researchers with respect to developing alternative tools for application to plant systems for improved safety and reliability. The research findings revealed that there is a need for researchers to develop alternative tools within the framework of RCM which are efficient in terms of processing and avoid the limitations of existing methodologies in order to have a safer and more reliable plant system.

Electric Power generation crisis in Nigeria: A Review of causes and solutions

The low power generation in Nigeria had hindered her economic growth and industrialisation. The nation had carried out various reform to ameliorate the electric power crisis but all to no avail. The electric power crisis has made so many industries to relocate to more environmental friendly nations. Furthermore, the terrible state of the nation’s basic infrastructure such as water supply, health care system and petroleum product distribution are all symptom of an economy that is insalubrious because of the nations’ incapability to meet electric power demand. The subject of power generation in Nigeria is interesting, vital and worthy of investigation. Some researchers have investigated the root causes of low power generation in Nigeria and they came up with diverse factors responsible for the lingering electric power crisis. In this research, a review of previous papers in the literature on factors responsible for the low power generation in Nigeria is performed. From the survey, an all-inclusive factors affecting power generation in Nigeria are presented and discussed. On the basis of the number of authors that cited the individual factor, the whole factors are ranked and categorised. Finally, in this paper, general solutions are proffered to minimise /eliminate the major challenges confronting power generation in Nigeria. The research findings revealed that the major challenges confronting power generation in Nigeria are factors such as poor plant maintenance, aged/obsolete equipment and gas pipe line vandalism and that these challenges can be minimised/eliminated through structured maintenance methodology and adequate funding among others