A case-based knowledge system for safety evaluation decision making of thermal power plants

Research on the Economic Benefit Evaluation of Combined Heat and Power (CHP) Technical Renovation Projects Based on the Improved Factor Analysis and Incremental Method in China

With the increasingly prominent problems of resources and environment, thermal power enterprises in China are facing more severe challenges. To improve energy efficiency, a great number of thermal power enterprises implement the technical renovation of equipment. However, current methods cannot meet the needs of scientific and effective evaluations. In this context, the internal rate of return (IRR) is used as the main index to evaluate the economic benefits of the technical renovation of combined heat and power (CHP) plants. In order to improve the accuracy of the economic benefit evaluation results, the incremental cash flow is calculated through the incremental method, which is based on the existence and non-existence method, and the improved factor analysis method is utilized to eliminate the influence of price factors from markets that have no direct and definite relationship with the technical renovation. Then, the evaluation method is validated by taking a CHP technical renovation project in B city of China as an example. By comparing with other methods, the results show that the IRRs calculated by different methods are quite different, and the difference between the maximum and the minimum can reach 69.95%. The result of the method proposed in this paper is more reasonable and reliable and can effectively evaluate the economic benefits of CHP technical renovation projects.

Case-Based Reasoning Model with Genetic Algorithms, Group Decision-Making and Template Reduction

Case retrieval, case reuse and case retention are critical to the reasoning performance of the traditional case-based reasoning (CBR) model. In this paper, the integrated use of template reduction technology (TR), genetic algorithms (GA), nearest neighbor (NN) rules and group decision-making (GDM) establishes the CBR-GDM model. First, the TR method of the case base is introduced. Then, an attribute weights optimization using GA is discussed in the case retrieval phase. After that, a case reuse method is carried out with NN and GDM. Finally, 10 data sets from UCI are used to carry out a comparison experiment by 5-fold cross-validation. The classification accuracy rate and the classification efficiency are analyzed under the small samples, before and after the data reduction. The results show that, combined with TR, GA and GDM, the pattern classification performance by CBR can be improved.

Knowledge based engineering approach for subsea pipeline systems’ FFR assessment

Purpose

– The purpose of this paper is to focus on developing a knowledge-based engineering (KBE) approach to recycle the knowledge accrued in an industrial organization for the mitigation of unwanted events due to human error. The recycling of the accrued knowledge is vital in mitigating the variance present at different levels of engineering applications, evaluations and assessments in assuring systems’ safety. The approach is illustrated in relation to subsea systems’ functional failure risk (FFR) analysis.

Design/methodology/approach

– A fuzzy expert system (FES)-based approach has been proposed to facilitate FFR assessment and to make knowledge recycling possible via a rule base and membership functions (MFs). The MFs have been developed based on the experts’ knowledge, data, information, and on their insights into the selected subsea system. The rule base has been developed to fulfill requirements and guidelines specified in DNV standard DNV-RP-F116 and NORSOK standard Z-008.

Findings

– It is possible to use the FES-based KBE approach to make FFR assessments of the equipment installed in a subsea system, focussing on potential functional failures and related consequences. It is possible to integrate the aforementioned approach in an engineering service provider’s existing structured information management system or in the computerized maintenance management system (CMMS) available in an asset owner’s industrial organization.

Research limitations/implications

– The FES-based KBE approach provides a consistent way to incorporate actual circumstances at the boundary of the input ranges or at the levels of linguistic data and risk categories. It minimizes the variations present in the assessments.

Originality/value

– The FES-based KBE approach has been demonstrated in relation to the requirements and guidelines specified in DNV standard DNV-RP-F116 and NORSOK standard Z-008. The suggested KBE-based FES that has been utilized for FFR assessment allows the relevant quantitative and qualitative data (or information) related to equipment installed in subsea systems to be employed in a coherent manner with less variability, while improving the quality of inspection and maintenance recommendations.