A rough set approach for evaluating vague customer requirement of industrial product-service system_Wenyan Songa

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6692 W. Song et al. Figure 5. The value and requirement around the customer activity of MRO. Third, the customer value, which is the common focus of stakeholders for the IPS 2 , is identified in this step by using the interviews and focus groups. Value here is actually the definition of the IPS 2 in terms of the requirement the industrial service is going to meet. For instance, to achieve the value of ‘High reliability, and long service life of air compressor’, the requirement ‘Efficient, and reliable MRO with accurate operation information of air compressor’ has to be fulfilled. That is, the requirement is the cost of achieving the value. Similarly, the value in the delivery of air compressor is mainly ‘Using immediately without time consuming for the starting period’. This value is related with the requirement ‘Filed guidance and training at the starting period’. Thus, in this way, the rest of requirements can be acquired. Fourth, Affinity Diagram is used to structure customer requirements. The elicited customer requirements are firstly interpreted into simple and representative expressions. For example, ambiguous requirement in the Figure 5 (Efficient, and reliable MRO with accurate operation information of air compressor) is represented by three concrete sub-requirements, i.e. ‘Disassembly and reassembly easily’, ‘24-h service (Feedback in 30 min, and on-site with spare parts in 3 h)’ and ‘Remote monitoring, early warning and failure diagnosis’. Similarly, other requirements could be also interpreted. Then, all the phrases would be bundled into many affinity groups, and the header with its group members could be obtained in Figure 6. 5.1.2 IPS 2 requirement prioritisation Step 1 Construct pair comparison matrix and test consistency An expert team is built for the evaluation IPS 2 requirement which consists of five experienced team members. They are procurement engineer, operator, end user, MRO engineer and IPS 2 designer. The work experience of experts ranged from 4 to 10 years in their own domains. Pair-wise comparisons between IPS 2 requirements are conducted in each hierarchy until each comparison matrix can get through the consistency test. Take the R 4 (Guarantee and optimisation of normal operation), for example (R 41 : Compressor flow P 7m 3 /min, discharge pressure P 0.8 Mpa; R 42 : Integrated structure; R 43 : no vibration and air flow pulse, noise < 75 dB; R 44 : Simple and comfortable manipulation; and R 45 : Energy saving rate: 18–35%), to illustrate computation process. The five experts’ comparison matrixes of requirement importance for R 4 are as follows:
International Journal of Production Research 6693 Figure 6. Hierarchical structure for IPS 2 requirement of rotary oil-free air compressor. According to formula (10) and (11), consistency ratio CR 1 = 0.010 < 0.1, CR 2 = 0.017 < 0.1, CR 3 = 0.029 < 0.1, CR 4 = 0.004 < 0.1 and CR 5 = 0.002 < 0.1, so the consistency of each pair-wise comparison matrix of the requirement R 4 (Guarantee and optimisation of normal operation) is acceptable. Then, the group evaluation matrix of requirement ~R 4 can be obtained by combining the above five pair-wise matrixes together. 2 ~R 4 ¼ 6 4 1; 1; 1; 1; 1 5; 7; 5; 3; 5 3; 3; 1=2; 1=3; 3 3; 5; 2; 2; 3 5; 3; 3; 1; 1=2 1=5; 1=7; 1=5; 1=3; 1=5 1; 1; 1; 1; 1 1=2; 1=3; 1=8; 1=8; 1=2 1=2; 1=2; 1=2; 1; 1=2 1; 1=3; 1=2; 1=3; 1=8 1=3; 1=3; 2; 3; 1=3 2; 3; 8; 8; 2 1; 1; 1; 1; 1 1; 3; 5; 7; 1 3; 1; 5; 3; 1=5 1=3; 1=5; 1=2; 1=2; 1=3 2; 2; 2; 1; 2 1; 1=3; 1=5; 1=7; 1 1; 1; 1; 1; 1 3; 1=3; 3; 1=2; 1=5 1=5; 1=3; 1=3; 1; 2 1; 3; 2; 3; 8 1=3; 1; 1=5; 1=3; 5 1=3; 3; 1=3; 2; 5 1; 1; 1; 1; 1 3 7 5
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Page 15 and 16: Table 4. Rough weight of IPS 2 requ

A rough set approach for evaluating vague customer requirement of industrial product-service system_Wenyan Songa

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