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122                 Alfonso T. Sarmiento and Edgar Gutierrez

                                                     INTRODUCTION


                          During  the  last  decade,  manufacturing  enterprises  have  been  under  pressure  to
                       compete in a market that is rapidly changing due to global competition, shorter product
                       life cycles, dynamic changes of demand patterns and product varieties and environmental
                       standards.  In  these  global  markets,  competition  is  ever  increasing  and  companies  are
                       widely  adopting  customer-focused  strategies  in  integrated-system  approaches.  In
                       addition, push manufacturing concepts are being replaced by pull concepts and notions of
                       quality systems are getting more and more significant.
                          Policy  analysis  as  a  method  to  generate  stabilization  policies  in  supply  chain
                       management  (SCM)  can  be  addressed  by  getting  a  better  understanding  of  the  model
                       structure  that  determines  the  supply  chain  (SC)  behavior.  The  main  idea  behind  this
                       structural  investigation  is  that  the  behavior  of  a  SC  model  is  obtained  by  adding
                       elementary behavior modes. For linear models the eigenvalues represent these different
                       behavior  modes  the  superposition  of  which  gives  rise  to  the  observed  behavior  of  the
                       system. For nonlinear systems the model has to be linearized at any point in time. Finding
                       the connection between structure and behavior provides a way to discover pieces of the
                       model where to apply policies to eliminate instabilities. However, other techniques are
                       required to determine the best values of the parameters related to the stabilization policy.
                          This work is motivated by the large negative impacts of supply chain instabilities.
                       Those impacts occur because instabilities can cause (1) oscillations in demand forecasts,
                       inventory levels, and employment rates and (2) unpredictability in revenues and profits.
                       These impacts amplify risk, raise the cost of capital, and lower profits. Modern enterprise
                       managers  can  minimize  these  negative  impacts  by  having  the  ability  to  determine
                       alternative policies and plans quickly.
                          Due to the dynamic changes in the business environment,  managers today rely on
                       decision technology  more than ever to make decisions. In the area of supply chain, the
                                        1
                       top  projected  activities  where  decision  technology  applications  have  great  potential  of
                       development are planning, forecasting, and scheduling (Poirier and Quinn, 2006).
                          This  chapter  presents  a  methodology  that  proposes  a  hybrid  scheme  for  a  policy
                       optimization approach with PSO to modify the behavior of entire supply chains in order
                       to achieve stability.


                       Policy Optimization


                          The policy optimization process uses methods based on mathematical programming
                       and algorithmic search to find an improved policy. Several optimization methods have

                       1  Decision technology adds value to network infrastructure and applications by making them smarter.
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