Page 189 - Materials Chemistry, Second Edition

9.4 Case study 187

SCH
Collection at
schools
Transport to
special work Storage &
centers by cleaning
DTD van
Collection at
houses Transport to biodiesel plant by tanker Biodiesel production

UCC
Cleaning at home Urban
collection
center

FIG. 9.2 The proceeding flows of three used cooking oils collection systems.

To analyze and select the best option among three alternatives, the revised group ZBWM
combined with the goal programming method were used. In this case study, the hierarchical
structure of criteria as shown in Fig. 9.3 requires separate comparison judgements. Therefore,
four rounds of comparisons and judgements were conducted, which included the compari-
son among perspectives, the comparison among environmental criteria, the comparison
among economic criteria, and the comparison among social criteria.
In this case study, two stakeholders are assumed to be participating in the decision
making process. One is an environmentalist, and the other is the top manager of the
recycling company. According to the standard of judgment, as shown in Table 9.4,the pref-
erences of criteria and perspectives provided by these two decision makers are presented
in Tables 9.5 and 9.6.
In this case study, two decision makers (p¼2) participated in selection of three used oil
treatment systems (m¼3) based on 29 criteria (n¼29), and the decision maker weights with
respect to the environmentalist and the top manager were set as 0.3 and 0.7, respectively
(λ 1 ¼0.3, λ 2 ¼0.7). According to Eq. (9.3) and Eq. (9.4), the criteria weights can be solved
by using the data listed in the decision-making matrix in Tables 9.5 and 9.6.Takingthe
perspective comparison as an example, the fuzzy weights of perspectives can be solved
by Eq. (9.8).