MINING METHOD SELECTION METODOLOGY BY MULTIPLE CRITERIA DECISION ANALYSIS - CASE STUDY IN COLOMBIAN...
Transcript of MINING METHOD SELECTION METODOLOGY BY MULTIPLE CRITERIA DECISION ANALYSIS - CASE STUDY IN COLOMBIAN...
ISAHP Article: Mu, Saaty/A Style Guide for Paper Proposals To Be Submitted to the
International Symposium of the Analytic Hierarchy Process 2014, Washington D.C., U.S.A.
International Journal of the
Analytic Hierarchy Process
1 Washington, D.C.
June 29 – July 2, 2014
MINING METHOD SELECTION METODOLOGY BY MULTIPLE
CRITERIA DECISION ANALYSIS - CASE STUDY IN
COLOMBIAN COAL MINING
Eng. Jorge Ivan Romero Gelvez M.I.
Escuela Colombiana de Carreras industriales
Bogotá, Colombia.
E-mail: [email protected]
Eng. Felix Antonio Cortes Aldana. Phd
Universidad Nacional de Colombia
Bogotá, Colombia.
E-mail: [email protected]
ABSTRACT
The purpose of this paper is to present an application of the AHP technique to a mining
method selection problem faced by a Colombian mining company; in this case we use
five decision makers. Next, a final aggregation of criteria priorities by AHP and
ENTROPY is proposed for include subjective and objective weighting. Next, VIKOR
method is performed to present a compromise solution; VIKOR is used to solve the
problem without decision makers dependence; the weights for VIKOR are aggregated
using an a priori λj subjective weighting obtained from AHP method. Whereas entropy weighting provides a dynamic and objective assessment of all criteria, AHP weighting
determine all decision makers preferences. Finally, an analysis of the results is carried out
to derive conclusions in relation to the effects of the modeling processes of both
techniques.
Keywords: Multicriteria decision making, selection problem, AHP, VIKOR, Entropy
weighting.
1. Introduction
This study wants to contribute to mining planning and design process. The problem of
selecting the mining method becomes the most important aspect of mining activities, and
you should select the method that best fits the unique criteria of each location, such as
spatial, geological, hydrogeological, geotechnical and other considerations such as
economic, technological and environmental factors. The performance of a subjective and
objective methodology will try to support the hard process of select the most suitable
mining extraction alternative.
Selecting the extractive method becomes the most important aspect of mining activities;
the selected method need to fits with unique criteria of each location, such spatial,
geological, hydrogeological, geotechnical and other considerations like economic,
technological and environmental factors. Such considerations or also called criteria,
usually in conflict have multiple stakeholders: environmental authorities, mining
IJAHP Article: Mu, Saaty/A Style Guide for Paper Proposals To Be Submitted to the
International Symposium of the Analytic Hierarchy Process 2014, Washington D.C., U.S.A.
International Symposium of
the Analytic Hierarchy
Process
2 Washington, D. C.
June 29 – July 2, 2014
authorities, mining companies, communities and others. In Colombia usually the final
decision maker becomes the Mining Engineer who works for the extractive company.
A mining company wants to choose the most suitable alternative for extracting coal
deposit located on the western side of Cerro Tasajero, Norte de Santander, Colombia.
This site was carefully studied by an interdisciplinary group of Geologists and Engineers
(among others). All data parameters of this deposit can be observed in Table 1. And also
can be proved by consulting the document: Regions and areas with coal in Colombia,
developed by (Mejia-umana & Pulido-gonzalez, 1993)
Table 1
Technical parameters Seam 20
Source: Own development based on information from the mining company
2. Literature Review
The selection of extraction methods in mining is one of the oldest challenges of humanity
and has been studied widely; about the most relevant scientific literature begins with the
first qualitative classification schemes extractive methods selection (Boshkov & Wright,
1973). In subsequent studies a classification system divides underground mining into
three groups based on ground conditions assigning each type of support required
(Morrison, 1976). (Laubscher, 1981) proposes a selection methodology for underground
mining method based on the RMR system (rock mass rating).
The first approach to a quantitative selection method is developed by (Nicholas, 1993)
with a numerical approach for the selection of extractive method (Selection Procedure -
A Numerical Approach); in this method a scale is formulated for the weighting of each
extraction method. Subsequently Hartman (H. Hartman & Mutmansky, 2002) developed
a qualitative selection scheme based on reservoir geometry and ground conditions to
choose the extractive method. Next, (Miller-Tait, Pakalnis, & Poulin, 1995) modified the
Nicholas method adding several criteria.
At present there are some approaches to the problem of mining method selection by
MCDA which include the application of fuzzy logic (Bitarafan & Ataei, 2004) and
(Karadogan, Kahriman, & Ozer, 2008) and we can find varied applications of AHP
(Alpay & Yavuz, 2009), (Azadeh, Osanloo, & Ataei, 2010) , (Bogdanovic, Nikolic, &
Ilic, 2012) and (Gelvez, Triana, & Aldana, 2012).
Parameter Quality
Thickness between 0.90 m y 2.10 m
Depth 600 m
Type Patty/Tabular
Grade distribution Uniform
Plunge Entre 12° y 20°
RSS (rock substance strength) Very Narrow
RMR (rock mass rating) between 21 y 40
IJAHP Article: Mu, Saaty/A Style Guide for Paper Proposals To Be Submitted to the
International Symposium of the Analytic Hierarchy Process 2014, Washington D.C., U.S.A.
International Symposium of
the Analytic Hierarchy
Process
3 Washington, D. C.
June 29 – July 2, 2014
3. Ubc method
The UBC (University of British Columbia) method was developed by (Miller-Tait
et al., 1995). This method rises by the need of improve the Nicholas technique
(Nicholas, 1993). As new add Miller introduces a -10 value for assign a negative
weight without discard completely any alternative. Moreover the rock mechanics
values are modify whit new ones. For more details can consult (Miller-Tait et al.,
1995)
4. Entropy method
The entropy method was developed by (Zeleny, 1982) as an objective method for
weighting criteria. This method assigns weights to each criterion based on the
decision matrix information, without reflect any decision maker preference
(Pomerol & Barba-Romero, 1997). The relative importance of the criteria j in a
decision situation, measured by weight wj, is directly related to the amount of
data inherently provided by the set of alternatives for this criterion. The more
diversity there is in the evaluations of the alternatives; greater importance should
be the criterion. The extent of this diversity is based on the concept of entropy in
an information channel proposed by (Shannon & Weaver, 2002). The procedure is
as follows:
Evaluations ija (i=1,m)(j=1,n) are normalized by sum fraction iji
a∑ of the
original evaluations of each j criterion. Entropy is determined by: (Ej).
1/log * *logj ij ijiE m a a− ∑ (1)
Where m= Number of alternatives in the normalized matrix, and ija = Normalized
criteria. Next, calculate the diversity (Dj).
1j jD E= − (2)
Normalized weight is calculated (Wj).
/ 1.0j j jjW D D= =∑
(3)
5.Vikor method
This method was developed by Serafim Opricovic in 1998. The VlseKriterijumska
Optimizcija I Kompromisno Resenje VIKOR method was developed for multicriteria
optimization of complex systems. It determines the compromise ranking-list, the
compromise solution, and the weight stability intervals for preference stability of the
compromise solution obtained with the initial (given) weights. This method focuses on
ranking and selecting from a set of alternatives in the presence of conflicting criteria. It
introduces the multicriteria ranking index based on the particular measure of ‘‘close-
ness’’ to the ‘‘ideal’’ solution (Serafim Opricovic & Tzeng, 2004). Acording (Quijano
Hurtado, 2012), based on (S Opricovic, 1998), Assuming that each alternative is
evaluated according to each criterion function, the compromise ranking could be
IJAHP Article: Mu, Saaty/A Style Guide for Paper Proposals To Be Submitted to the
International Symposium of the Analytic Hierarchy Process 2014, Washington D.C., U.S.A.
International Symposium of
the Analytic Hierarchy
Process
4 Washington, D. C.
June 29 – July 2, 2014
performed by comparing the measure of closeness to the ideal alternative. The
multicriteria measure for compromise ranking is developed from the Lp-metric used as an
aggregating function in a compromise programming method (Yu, 1973; Zeleny, 1982).
The set of alternatives “J” are noted by A1, A2, Aj……..Am. For alternative Aj, The
rating of ith aspect is noted byijf , for example ijf is the ith value of the criterion for
alternative Aj; m is the number of alternatives, n is the number of criteria. Development
of the VIKOR method started with the following form of Lp-metric:
( ) ( )1/
* *
,
1
/
ppn
p j i i ij i i
i
L w f f f f −
=
= − − ∑
(4)
1 ; j 1, 2,...., J .p≤ ≤ ∞ =
This Lp distance concept, represents the Manhattan and Chevishev distances for and
values. Uses the L1 norm, where p=1 and corresponds to the mayor distance between two
points. In the second case, for calculation vikor uses the chevishev norm that is the
short distance between two points, where (Bellver & Martinez, 2013; Serafim
Opricovic & Tzeng, 2004). According (Quijano Hurtado, 2012) based on (Serafim
Opricovic & Tzeng, 2007) the procedure is as follows:
a) Determine the best *
if and the worst if− values of all criterion functions i=1,2,….,n,
If the ith function represents a benefit then * maxi ijf f= and mini ijf f− = .
b) Compute the values Sj and Rj, j = 1,2,……,J by the relations
( ) ( )* *
0/
n
j i i ij i iS w f f f f −= − −∑ (5)
( ) ( )* *max /j i i i ij i iR w f f f f − = − − (6)
c) Compute
jQ values by the relation
( )( ) ( )
( )( )
* *
* *1
j
j jS S R Rv
S S R RQ v
− −
− −+ −
− −=
(7)
d) Rank the alternatives, sorting by the values S, R and Q, in decreasing order. The
results are three ranking lists. S, R y Q.
e) A(1) = Q (mín) is the compromise solution if:
I. Acceptable advantage. (2) (1)( ) ( ) ,Q A Q A DQ− ≥
Where 1/ ( 1)DQ J= − and (2)A is the second alternative in the Q ranking
list.
IJAHP Article: Mu, Saaty/A Style Guide for Paper Proposals To Be Submitted to the
International Symposium of the Analytic Hierarchy Process 2014, Washington D.C., U.S.A.
International Symposium of
the Analytic Hierarchy
Process
5 Washington, D. C.
June 29 – July 2, 2014
II. Acceptable stability in decision making. Alternative (1)A must be the best
also in S or R.
6.Research Design/Methodology
According Saaty and Peniwaty when the members of a group are all experts who do not
wish to participate in the judgment process but prefer to obtain their own answer after the
group has structured a decision, we can apply the geometric mean or the mean weighted
by the importance of the experts to the different individuals’ final outcome to obtain an
overall final outcome (Saaty & Peniwati, 2008). In this paper 5 decision makers play the
role of experts and solve the problem individually, next all judgments are unify by the
geometric mean.
For MCDA will be taken as valid alternatives which have a positive weighting to apply
the technique UBC (Miller-Tait et al., 1995) thereby eliminating alternatives that are not
only technically feasible and applicable alternatives left. While there are a good amount
of extractive methods, this problem only considers 9 of the 10 methods described in
(Nicholas 1993) and (Hartman & Mutmansky 2002): Alternative 1 (Open pit), alternative
2 (Block caving), alternative 3 (Sublevel Stopping), alternative 4 (sublevel caving),
alternative 5 (long wall), alternative 6 (room and pillar), alternative 7 (Shrinkage
Stopping), alternative 8 (Cut and fill), alternative 9 (Square set).
Criterion 1 Spatial characteristics of the
deposit.
Sc1. Size - Maximize
Sc2. Shape - Maximize
Sc3. Plunge - Maximize
Sc4. Depth - Maximize
Criterion 2 Geological and
hydrogeological conditions and
geotechnical properties.
Sc5. Distribution - Maximize
Sc6. Rock mass ratings (RMR) -
Maximize
Sc7. Rock substance strength (RSS) -
Maximize
Criterion 3 Economic considerations
Sc8. Performance rate - Maximize
Sc9. Production - Maximize
Sc10. Capital Investment - Minimize
Sc11. Productivity - Maximize
Sc12. Comparative costs of possible
mining methods. Minimize
Criterion 4 Technological factors
Sc13. Mine Recuperation - Maximize
Sc14. Dilution - Minimize
Sc15. Flexibility - Maximize
Sc16. Selectivity - Maximize
Criterion5 Environmental
Considerations
Sc17. Stability of the openings -
Maximize
Sc18. Subsidence or effects on the
surface of excavation - Maximize
Sc19. Health and safety conditions –
Maximize
In (Gelvez et al., 2012) is proposed a generic decision matrix as we can see in Table 2,
this matrix is based on (H. L. Hartman & Mutmansky, 2002) values. The scale: Higuest
5, High 4, Moderate 3, Low 2, Lowest 1; Escala 2: Good 3, Moderate 2, Poor 1; Escala 3:
Large scale 4, Large 3, Moderate 2, Small 1; Escala 4: Large 4, High 3, Moderate 2 and
Small 1 is transformed in objective values, see table 3
Table 2. Generic decision matrix. Source: Own development based on (H. L. Hartman &
Mutmansky, 2002; Miller-Tait et al., 1995)
IJAHP Article: Mu, Saaty/A Style Guide for Paper Proposals To Be Submitted to the
International Symposium of the Analytic Hierarchy Process 2014, Washington D.C., U.S.A.
International Symposium of
the Analytic Hierarchy
Process
6 Washington, D. C.
June 29 – July 2, 2014
C Sc A1 A2 A3 A4 A5 A6 A7 A8 A9
Sc1
Sc2
Sc3
Sc4
Sc5
Sc6
Sc7
Sc8 Rapid Slow Moderate Moderate Moderate Rapid Rapid Moderate Slow
Sc9 Large Scale Large Large Large Large Large Moderate Moderate Small
Sc10 Large High Moderate Moderate High High Low Moderate Low
Sc11 High Low Low Moderate High High Low Moderate Low
Sc12 5 10 20 15 15 20 45 55 100
Sc13 High High Moderate High High Moderate High High Higuest
Sc14 Moderate High Moderate Moderate Low Moderate Low Low Lowest
Sc15 Moderate Low Low Moderate Low Moderate Moderate Moderate High
Sc16 Low Low Low Low Low Low Moderate High High
Sc17 High Moderate High Moderate High Moderate High High High
Sc18 High High Low High High Moderate Low Low Low
Sc19 Good Good Good Good Good Good Good Moderate Poor
C1
C2
C3
C4
C5
Table 3. Numeric generic decision matrix. Source: Own development based on (H. L.
Hartman & Mutmansky, 2002; Miller-Tait et al., 1995)
C Sc A1 A2 A3 A4 A5 A6 A7 A8 A9
Sc1
Sc2
Sc3
Sc4
Sc5
Sc6
Sc7
Sc8 3 1 2 2 2 3 3 2 1
Sc9 4 3 3 3 3 3 2 2 1
Sc10 4 3 2 2 3 3 1 2 1
Sc11 4 2 2 3 4 4 2 3 2
Sc12 5 10 20 15 15 20 45 55 100
Sc13 4 4 3 4 4 3 4 4 5
Sc14 3 4 3 3 2 3 2 2 1
Sc15 3 2 2 3 2 3 3 3 4
Sc16 2 2 2 2 2 2 3 4 4
Sc17 4 3 4 3 4 3 4 4 4
Sc18 4 4 2 4 4 3 2 2 2
Sc19 3 3 3 3 3 3 3 2 1
C1
C2
C3
C4
C5
IJAHP Article: Mu, Saaty/A Style Guide for Papers Submitted to the International Journal of the
Analytic Hierarchy Process
International Journal of the
Analytic Hierarchy Process
7 Vol. 3 Issue 1 2011
ISSN 1936-6744
Figure 1. Proposed methodology for mining method selection Source: Own development
based on information from the mining
7. Data/Model Analysis
Table 4. Decision Matrix. Source: Own development
sc1 sc2 sc3 sc4 sc5 sc6 sc7 sc8 sc9 sc10 sc11 sc12 sc13 sc14 sc15 sc16 sc17 sc18 sc19
wj 4,28% 4,42% 4,28% 4,28% 4,29% 4,34% 4,41% 5,50% 5,78% 5,75% 5,34% 10,58% 4,72% 5,75% 5,10% 5,67% 4,41% 5,32% 5,78%
A1 54 40 52 52 54 53 50 2 3 2 2 20 3 3 2 2 4 2 3
A2 54 54 54 53 54 61 62 2 3 3 4 15 4 2 2 2 4 4 3
A3 54 54 54 52 54 50 50 3 3 3 4 20 3 3 3 2 3 3 3
A4 54 54 51 54 52 59 64 2 2 2 3 55 4 2 3 4 4 2 2
A5 51 54 52 52 50 59 61 1 1 1 2 100 5 1 4 4 4 2 1
ma
x
ma
x
ma
x
ma
x
ma
x
ma
x
ma
x
ma
x
ma
x
min
ma
x
min
ma
x
min
ma
x
Ma
x
Ma
x
min
ma
x
c1 c2 c3 c5c4
Figure 2. Assigning weights by entropy method Source: Own development
IJAHP Article: Mu, Saaty/A Style Guide for Papers Submitted to the International Journal of the
Analytic Hierarchy Process
International Journal of the
Analytic Hierarchy Process
8 Vol. 3 Issue 1 2011
ISSN 1936-6744
Figure 3. Aggregation of AHP decision makers and Entropy weigths Source: Own
development based on information from the mining company
Figure 4. Hierarchy and AHP results Source: Own development based on information
from the mining company
Table 2. VIKOR results. Source: Own development
Q S R
Sublevel Stoping 0,56874757 0,519571919 0,05748521
Longwall 0,06874757 0,325995775 0,05748521
Room and Pillar 0,39339684 0,451684482 0,05748521
Cut and Fill 0,0374675 0,340501405 0,04978445
Square Set 0,95987655 0,504038032 0,10579196
IJAHP Article: Mu, Saaty/A Style Guide for Papers Submitted to the International Journal of the
Analytic Hierarchy Process
International Journal of the
Analytic Hierarchy Process
9 Vol. 3 Issue 1 2011
ISSN 1936-6744
Figure 5. Vikor performance analysis. Source: Own development
8. Conclusions
The results Vikor, show a set of compromise solutions (cut and fill - long wall) which are
accepted by experts involved in the decision process. The results of the AHP method
show decision makers preferences for “long wall” in this particular problem. The overall
inconsistency was 5%. Finally for this deposit the company used long wall method, a
finding consistent with the subjective and objective analysis proposed in this
methodology.
The results obtained in this work allow evidence as this Methodology Vikor-AHP, works
to improve the process of decision-making, since it allows structured in a logical way a
lot of information, both the problem and the possible solutions that can be pose.
REFERENCES
Alpay, S., & Yavuz, M. (2009). Underground mining method selection by decision
making tools. Tunnelling and Underground Space Technology. Retrieved from
http://www.sciencedirect.com/science/article/pii/S0886779808000758
Azadeh, A., Osanloo, M., & Ataei, M. (2010). A new approach to mining method
selection based on modifying the Nicholas technique. Applied Soft Computing.
Retrieved from
http://www.sciencedirect.com/science/article/pii/S1568494609001628
Bellver, J. A., & Martinez, F. G. (2013). NUEVOS METODOS DE VALORACION
MODELOS MULTICRITERIO.
Bitarafan, M., & Ataei, M. (2004). Mining method selection by multiple criteria decision
making tools. The Journal of The South African Institute of …. Retrieved from
http://www.saimm.co.za/Journal/v104n09p493.pdf
Bogdanovic, D., Nikolic, D., & Ilic, I. (2012). Mining method selection by integrated
AHP and PROMETHEE method. Anais da Academia Brasileira de …. Retrieved
IJAHP Article: Mu, Saaty/A Style Guide for Papers Submitted to the International Journal of the
Analytic Hierarchy Process
International Journal of the
Analytic Hierarchy Process
10 Vol. 3 Issue 1 2011
ISSN 1936-6744
from http://www.scielo.br/scielo.php?pid=S0001-
37652012005000013&script=sci_arttext
Boshkov, S., & Wright, F. (1973). Basic and parametric criteria in the selection, design
and development of underground mining systems. SME Mining Engineering
Handbook. Retrieved from
http://scholar.google.es/scholar?q=related:cruVbYFsOM0J:scholar.google.com/&hl
=es&as_sdt=0,5#2
Gelvez, J., Triana, L., & Aldana, F. (2012). Selección del método de explotación minera
a partir de información cuantificada aplicando técnicas de decisión multicriterio.
enid.unal.edu.co. Retrieved from
http://www.enid.unal.edu.co/2012/memorias/fscommand/recursosmateriales/31.pdf
Hartman, H. L., & Mutmansky, J. M. (2002). Introductory Mining Engineering (p. 570).
John Wiley & Sons. Retrieved from
http://books.google.ca/books/about/Introductory_Mining_Engineering.html?id=jPd
F6K0at4YC&pgis=1
Hartman, H., & Mutmansky, J. (2002). Introductory mining engineering. Retrieved from
http://books.google.es/books?hl=es&lr=&id=jPdF6K0at4YC&oi=fnd&pg=PR11&d
q=Introductory+Mining+Engineering.+&ots=AFB85Tbo8R&sig=1OQcQRfkJidr9p
VWYYvOa946w_g
Karadogan, A., Kahriman, A., & Ozer, U. (2008). Application of fuzzy set theory in the
selection of underground mining method. The journal of the southern african
institute of mining and metallurgy, (February), 73–79.
Laubscher, D. (1981). Selection of mass underground mining methods. Design and
operation of caving …. Retrieved from
http://scholar.google.es/scholar?q=Selection+of+Mass+Underground+Mining+Met
hods%2C%E2%80%99+Design+and+Operation+of+Caving+and+Sublevel+Stopin
g+Mines&btnG=&hl=es&as_sdt=0%2C5#0
Mejia-umana, L. J., & Pulido-gonzalez, O. (1993). Regiones y zonas con carbón en
Colombia. Revista De La Facultad De Ciencias Basicas, (18).
Miller-Tait, L., Pakalnis, R., & Poulin, R. (1995). UBC mining method selection. Mine
Planning and …. Retrieved from
http://books.google.com/books?hl=es&lr=&id=T4SrrygPF1QC&oi=fnd&pg=PA16
3&dq=related:LPy1Y9e3FwwJ:scholar.google.com/&ots=Ax9VIfGvAT&sig=aE2g
prILKHCRA7-9KLnw2KV85B4
Morrison, R. (1976). A Philosophy of Ground Control: A Bridge Between Theory and
Practice. Retrieved from http://www.getcited.org/pub/101913262
Nicholas, D. (1993). Selection procedure. Mining engineering handbook, Hartman H,
SME, New …. Retrieved from
http://scholar.google.es/scholar?q=related:cruVbYFsOM0J:scholar.google.com/&hl
=es&as_sdt=0,5#3
Opricovic, S. (1998). Multicriteria optimization of civil engineering systems. Faculty of
Civil Engineering, Belgrade. Retrieved from
http://scholar.google.es/scholar?hl=es&q=Opricovic,+S.+(1998).+&btnG=&lr=#3
Opricovic, Serafim, & Tzeng, G.-H. (2004). Compromise solution by MCDM methods:
A comparative analysis of VIKOR and TOPSIS. European Journal of Operational
Research, 156(2), 445–455. doi:10.1016/S0377-2217(03)00020-1
Opricovic, Serafim, & Tzeng, G.-H. (2007). Extended VIKOR method in comparison
with outranking methods. European Journal of Operational Research, 178(2), 514–
529. doi:10.1016/j.ejor.2006.01.020
IJAHP Article: Mu, Saaty/A Style Guide for Papers Submitted to the International Journal of the
Analytic Hierarchy Process
International Journal of the
Analytic Hierarchy Process
11 Vol. 3 Issue 1 2011
ISSN 1936-6744
Pomerol, J., & Barba-Romero, S. (1997). Decisiones multicriterio: fundamentos teóricos
y utilización práctica. Colección de Economía. Servicio de Publicaciones.
Universidad de Alcalá de Henares. Retrieved from
http://scholar.google.es/scholar?q=Decisiones+Multicriterio.+Fundamentos+Teóric
os+y+Utilización+Práctica,&btnG=&hl=es&as_sdt=0,5#3
Quijano Hurtado, R. (2012). Diseño e implementación de una plataforma integrada de
modelación para la planificación energética sostenible -Modergis estudio de caso
Colombia". Universidad Nacional de Colombia, Sede Medell’in. Retrieved from
http://www.bdigital.unal.edu.co/8179/
Saaty, T. L., & Peniwati, K. (2008). Group Decision Making: Drawing Out and
Reconciling Differences. RWS Publications.
Yu, P. L. (1973). A Class of Solutions for Group Decision Problems. Management
Science. doi:10.1287/mnsc.19.8.936
Zeleny, M. (1982). Multiple criteria decision making. McGraw-Hill series in quantitative
methods for …. Retrieved from http://library.wur.nl/WebQuery/clc/173382