ABSTRACT
This present paper is an investigation of a framework for Safety-Critical Maritime Infrastructure (SCMI) evaluation. The framework contains three Multi-Criteria Decision-Making (MCDM) tools, namely: fuzzy Step-wise Weight Assessment Ratio Analysis (SWARA), Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and Weighted Aggregates Sum Product Assessment (WASPAS). It also contains five safety practice criteria: people's safety, property safety and monitoring capabilities, response to regular and irregular threats in a robust yet flexible manner, and breaches in physical security. The framework has four safety culture criteria: learning from experience and inter-element collaboration, lack of facility maintenance, and anticipating risk events and opportunities. Through the framework, an evaluation of the safety practices and safety culture of six Nigerian seaports is done. Then, data obtained from the ports in regard to their safety practices and culture were analysed in line with the framework identified and adopted. The results revealed that the safety of people's life is the most important safety practice and contributed about 47.90% to evaluate the SCMI. Results equally showed that the most significant safety culture is learning from experience, and accounted for approximately 53.20% in assessing the SCMI. Similarly, the TOPSIS method ranked Warri (A5) and Tin Can Island A1 as the best and worst safety practices performance, respectively. Results of analyses on the TOPSIS showed that Apapa port (A2) and Onne port (A6) had the best and worst performances correspondingly. WASPAS was also analysed. The results indicated that A6 performed the best safety practice performance, while A2 had the worst safety practice performance. Analysis of the WASPAS method was equally done. It showed that A1 had the worst safety culture performance, while A5 had the best safety culture performance. Therefore, the proposed framework could serve as a veritable tool for analysing SCMI by using safety practice and safety culture criteria.
ABSTRACT
This paper analyzes the adoption of an off-grid hybrid renewable energy system (HRES) for a high-rise building owned by a public institution in Nigeria. The analysis is based on the comparison between the use of a single criterion and multiple criteria in the selection of the most feasible energy system. The proposed HRES comprises of a wind turbine, diesel generator, photovoltaic (PV), and battery storage system. Hybrid optimization of multiple energy resources (HOMER) software was used to design the HRES for a case study (based on a single criterion-total net present cost), while Evaluation Based on Distance from Average Solution (EDAS) method was used to evaluate the effect of choosing an optimal system based on multiple criteria. Based on the simulations conducted with HOMER, eight feasible HRES (ES1-ES8) were identified. When the feasible HRES were ranked based on total (NPC), the optimal configuration comprises 70 kW PV modules, 20 kW diesel generating set, 40 kW converter, and 70, 3000 Ah batteries. The results obtained from the optimization process were subjected to a multi-criteria analysis based on sustainability principles. The ranking of the first two systems (ES1 and ES2) returned by single criterion (total NPC) remained the same, while changes were observed in the ranks of the remaining systems (ES3-ES8). This modular feasibility study shows that it would be economical to power the entire university using HRES. It is expected that this study would help the university communities and other stakeholders make informed decision during the planning stage of similar projects.
