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Modern logistics as the organization and management of a state-of-the-art technology , is widely considered to be an important source of profits for the enterprises in the lower material consumption , improve labor productivity , and plays an important role in the national economic and social development . In the logistics and distribution system , through a scientific and reasonable method to determine the transport route and time , not only can reduce operating costs , can also accelerate the speed of material distribution , improve operational efficiency and ensure customer service levels . Logistics distribution vehicle scheduling problem (Vehicle Routing Problem, referred to as VRP) is an NP-hard problem , and the problem was first proposed in 1959 by Dantzig and Ramser . Many problems can be abstract for this problem soon cause great importance of the disciplines of operations research , applied mathematics , combinatorics, graph theory and network analysis , logistics, science, computer applications , and transport plans makers and has been the forefront of the hot issues of the field of operations research and combinatorial optimization . Based on existing research , this research vehicle scheduling problem with time windows ( VehicleRouting Problem with Time Windows , referred VRPTW ) , the problem can be simply described as follows: starting the vehicle from the site to complete the distribution needs of customers , to meet the capacity the total cost and time window constraints , choose the right path , so that the completion of the distribution of all customers needs required minimum . The analysis the VRPTW has the characteristics as well as the problems in the past , based on simulated annealing algorithm used in solving the problem . First SWEEP algorithm to build the initial path , then through the simulated annealing algorithm to obtain the satisfied solution , 2-interchange technology to build a neighborhood in the solution of the improvement process . Finally, the experimental test , the algorithm can solve VRPTW problems of a certain size , and the temperature dropped faster algorithm are analyzed .
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