dynamiclocationproblems动态选址问题

上传人:自*** 文档编号:80708290 上传时间:2019-02-19 格式:DOC 页数:9 大小:171KB
返回 下载 相关 举报
dynamiclocationproblems动态选址问题_第1页
第1页 / 共9页
dynamiclocationproblems动态选址问题_第2页
第2页 / 共9页
dynamiclocationproblems动态选址问题_第3页
第3页 / 共9页
dynamiclocationproblems动态选址问题_第4页
第4页 / 共9页
dynamiclocationproblems动态选址问题_第5页
第5页 / 共9页
点击查看更多>>
资源描述

《dynamiclocationproblems动态选址问题》由会员分享,可在线阅读,更多相关《dynamiclocationproblems动态选址问题(9页珍藏版)》请在金锄头文库上搜索。

1、Dynamic location problemsFields of applicationNetworks:- This group includes communication, electric power, gas distribution and other networks.- The subject is to find a good expansion plan with a special interest on routing decisions.- Transportation costs are often the most important variable cos

2、ts.Heavy process industries:- This group includes aluminium, cement, steel, caustic soda, nitrogenous fertiliser and related industries.- In these industries transportation costs are again important.Public services:- This group includes the placement of schools, hospitals and other public services.

3、- The decision often depends on social, environmental and political constraints.Two-echelon plant location problem: - The two-echelon plant is a enterprise with two different distribution stages, a manufacturing plant and a warehouse facility.- These cases often include different facility types and

4、commodities.- Transportation costs between the two stages are an important cost driver. Dynamic location problemsWhat is the reason for using dynamic instead of static location approaches?Capacity expansion:- An increasing demand made it necessary to find an optimal expansion schedule. This can only

5、 be solved by dynamic approaches.- Some dynamic location problems are also able to handle a decreasing demand in some periods.- The amount of salvage value (or closing costs) compared with the set-up costs (or reopening costs) has a strong effect on tending to change locations over the time horizon.

6、 - The objective of expansion problems could be to satisfy every known demand with minimum costs (especially transportation costs), or profit maximisation.Modernisation: - Budget constraints made it necessary to modernise a network stepwise.- Dynamic approaches could help to concentrate modernisatio

7、n on the most profitable locations first.- An example for a modernisation problem is the switching from analog to digital technology in the transition network for telecommunication lines.It is possible to combine the modernisation and the capacity expansion problem.Dynamic location problemsThe basic

8、 dynamic location problem could be described as: (1)subject to for all j, t (2) for all j, t (3) ; for all i, j, t (4)whereT = the number of periods in the planning horizon;I = the index set of facility locations;J = the index set of demand locations in the network; = the transportation cost of serv

9、ing a unit of demand at node (market) jby a facility in location i in period t; = the demand generated by node (market) j in period t; = the set-up cost per unit of capacity in location i in period t.The decision variables in this problem are: = a fraction of costumer js demand in period t served by

10、 location i; = the capacity installed in location i in period t.Dynamic location problemsSolution techniques:The following figure shows the growth in CPU time (in seconds) in a five location case dependent on the time horizon. One could see that arc path linear programming leads to fast growing CPU

11、time. Real live problems often require integer solutions, which can be achieved by Lagrangian Relaxation and Branch and Bound heuristics.Rounded linear programming solutions are extremely close to the optimal solution but they are often violating some constraints. (These mathematical infeasible solu

12、tions are often acceptable for practical purposes.)The Dynamic Capacitated Plant Location Problem (DCPLP):- Is a special case of the dynamic location problems.- Different facility types can be part of the optimal solution.- Capacitated means that the capacity per facility type is limited.- Plant is

13、defined as a collection of facilities in the same location. (- The number of facilities in the same plant-location is limited.)- The DCPLP allows to include economies of scale. Bigger facilities have lower costs per unit, but few plants with big facilities lead to higher transportation costs.The tas

14、k of the DCPLP is to find a trade off between costs per unit and transportation costs.The mathematical formulation of the DCPLP:The DCPLP objective consists of three cost terms; transportation costs, costs per unit, and set-up costs. Transportation costs are given by (5)where = the set of facilities which can be placed in location ;= is a decision variable and stands for the fra

展开阅读全文
相关资源
相关搜索

当前位置:首页 > 中学教育 > 试题/考题 > 初中试题/考题

电脑版 |金锄头文库版权所有
经营许可证:蜀ICP备13022795号 | 川公网安备 51140202000112号