现代物流与供应链管理 (16).ppt

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1、Modeling of Distribution OptimizationMotivation Problem description Modeling目目录Algorithms Motivation Cost savingEffectiveEnvironmental friendlyDistrbution CenterDemandsDemandsDemandsDemandsDemandsDistrbution CenterProblem description Given a DC,known as“depot-0”,which provides a fleet of identical v

2、ehicle ,each vehicle kK characterized by:its capacity=QkGiven a set of consumers I,each consumer iI characterized by:the amount of demands qiSets¶meter DCProblem description Find the subset of links in A that link the depot and all consumers by tours with lowest travel cost does not exceed the v

3、ehicle capacity QkSolutions of Distribution optimization DCModelingHow to model an optimization problem-choose some decision variables they typically encode the result we are interested in-express the problem constraints in terms of these variables they specify what the solution to the problem are -

4、express the objective function the objective function specifies the quality of each solutionOptimization models ModelingThe result is an optimization model-it is a declarative formulation they specify the“what”,not to“how”-there may be many ways to model an optimization problem Optimization model Mo

5、deling Objective function-Capture the total travel costDistribution optimization model Decision variables -denotes whether link(i,j)A is visited by vehicle k in the solution(i,j)=1 means vehicle visits node j right after visiting node i =0 means link(i,j)A is not visited by vehicle kDCMotivation Add

6、itional considerations:Multiple depots Time windowsHeterogenous fleetsDistribution optimization model Problem constraints-consumers must be visited and can only be visited once-a vehicle enters one node must leave the node-vehicle capacity constraints-subtours elimination constraints DCModeling xij0,1,i,jNuik,ujk0,i,jJ,kKDistribution optimization model minimizeSubject to:Modeling Complexity:Exponential growth Not all of them are feasible-They cannot against the constraints