An interval valued pythagorean fuzzy quality function deployment method and its application to solar photovoltaic technology development

Quality function deployment (QFD) is a focused methodology for carefully listening to the voice of the customer and then effectively responding to those needs customer requirements (CRs) and expectations through design requirements (DRs). In classical QFD, exact numbers are used to determine the priorities of the CRs and the position of the company among the competitors. However, vagueness and impreciseness are inevitable uncertainties in these kinds of human evaluations, which are generally realized by linguistic terms. In this thesis, the uncertainty in design processes are captured by a relatively new extension of ordinary fuzzy sets, Pythagorean fuzzy sets (PFS), aiming at presenting a larger domain to experts for assigning a membership degree and a non-membership degree together with their hesitancy. All the evaluation processes in the house of quality (HOQ) are performed based on interval-valued PFS (IVPFS) and present some novel definitions for measuring and prioritizing CRs and DRs, and determining the position of the company among the competitors. An application of the proposed PF-HOQ model for solar photovoltaic (PV) technology development is given. The hypothetical case study is based on three cutomers' and three experts' evaluations. The HOQ is built by considering 6 CRs and 8 DRs. Some optional parts of a HOQ such as correlation matrix, organizational difficulty, directions of improvement and competitor analysis are also taken into consideration. The thesis is organized as follows. Section 1 is the introduction part. Section 2 introduces the concepts of QFD. Section 3 presents a literature review on Fuzzy QFD (FQFD). Section 4 gives the preliminaries for PFSs. Section 5 develops an IVPF QFD Model. Section 6 illustrates the application of the proposed model on solar photovoltaic technology development. Section 7 concludes the paper with future directions.