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A linear programming and sampling approach to the cutting-order problem.

机译:解决订单问题的线性规划和采样方法。

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摘要

In the context of forest products, a cutting order is a list of dimension parts along with demanded quantities. The cutting-order problem is to minimize the total cost of filling the cutting order from a given lumber grade (or grades). Lumber of a given grade is supplied to the production line in a random sequence, and each board is cut in a way that maximizes the total value of dimension parts produced, based on a value (or price) specified for each dimension part. Hence, the problem boils down to specifying suitable dimension-part prices for each board to be cut.; T'he method we propose is adapted from Gilmore and Gomory's linear programming approach to the cutting stock problem. The main differences are the use of a random sample to construct the linear program and the use of prices rather than cutting patterns to specify a solution. The primary result of this thesis is that the expected cost of filling an order under the proposed method is approximately equal to the minimum possible expected cost, in the sense that the ratio (expected cost divided by the minimum expected cost) approaches one as the size of the order (e.g., in board feet) and the size of the random sample grow large.; A secondary result is a lower bound on the minimum possible expected cost. The actual minimum is usually impractical to calculate, but the lower bound can be used in computer simulations to provide an absolute standard against which to compare costs. It applies only to independent sequences, whereas the convergence property above applies to a large class of dependent sequences, called alpha-mixing sequences.; Experimental results (in the form of computer simulations) suggest that the proposed method is capable of attaining nearly minimal expected costs in moderately large orders. The main drawbacks are that the method is computationally expensive and of questionable value in smaller orders.
机译:在林产品的环境中,切割订单是一列尺寸零件以及所需数量的清单。切割顺序问题是使给定木材等级(或多个等级)满足切割订单的总成本降至最低。给定等级的木材以随机顺序供应到生产线,并且根据为每个尺寸零件指定的值(或价格),以使所生产尺寸零件的总价值最大化的方式切割每块木板。因此,问题归结为为每个要切割的板指定合适的尺寸零件价格。我们建议的方法是根据Gilmore和Gomory的线性规划方法改编而成的,用于解决切削问题。主要区别在于使用随机样本构建线性程序,以及使用价格而非削减模式来指定解决方案。本论文的主要结果是,在该比率(预期成本除以最小预期成本)的范围内,按预期方法执行某订单的预期成本大约等于最小可能预期成本。数量级(例如,以板英尺为单位),随机样本的大小会变大。次要结果是最小可能预期成本的下限。计算实际最小值通常是不切实际的,但是可以在计算机模拟中使用下限来提供一个用于比较成本的绝对标准。它仅适用于独立序列,而上述收敛属性适用于一大类相关序列,称为alpha混合序列。实验结果(以计算机模拟的形式)表明,所提出的方法能够以中等数量的订单获得接近最低的预期成本。主要缺点是该方法计算量大,并且在较小订单中具有可疑的价值。

著录项

  • 作者

    Hamilton, Evan Douglas.;

  • 作者单位

    Oregon State University.;

  • 授予单位 Oregon State University.;
  • 学科 Statistics.; Operations Research.
  • 学位 Ph.D.
  • 年度 2001
  • 页码 242 p.
  • 总页数 242
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 统计学;运筹学;
  • 关键词

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