14,887 research outputs found
An optimization framework for solving capacitated multi-level lot-sizing problems with backlogging
No full textThis paper proposes two new mixed integer programming models for capacitated multi-level lot-sizing problems with backlogging, whose linear programming relaxations provide good lower bounds on the optimal solution value. We show that both of these strong formulations yield the same lower bounds. In addition to these theoretical results, we propose a new, effective optimization framework that achieves high quality solutions in reasonable computational time. Computational results show that the proposed optimization framework is superior to other well-known approaches on several important performance dimensions
Mixed integer programming in production planning with backlogging and setup carryover : modeling and algorithms
Get PDFThis paper proposes a mixed integer programming formulation for modeling the capacitated multi-level lot sizing problem with both backlogging and setup carryover. Based on the model formulation, a progressive time-oriented decomposition heuristic framework is then proposed, where improvement and construction heuristics are effectively combined, therefore efficiently avoiding the weaknesses associated with the one-time decisions made by other classical time-oriented decomposition algorithms. Computational results show that the proposed optimization framework provides competitive solutions within a reasonable time
Analysis of the Effects of Large Lot Zoning
Get PDFThis study extends a test for the presence of binding zoning, originally developed to be applied across many adjacent jurisdictions, so that it can be applied within a single jurisdiction. This study also demonstrates how to carry out this test in the presence of spatially correlated OLS residuals by using a mixed effects model whose coefficients are estimated using the maximum likelihood technique. The study examines twenty years of land sales data from a Midwestern county containing two adjacent cities surrounded by rural areas. A thirty-five-acre acre, minimum lot size in the rural area is found to be binding; while a 9,000 square foot minimum lot size in the cities is found to be not binding.
The common lot /
No full textMode of access: Internet.OSU's c.2 part of Grosset & Dunlap Collection.OSU's copy 2 bound in red cloth.OSU's copy 2: "Set up and electrotyped. Published September 1904. Reprinted October, November twice, 1904; January, February, March, 1905; June 1906.
A Comprehensive Review of Lot Streaming
Get PDF[[abstract]]"Lot streaming combined lot splitting with operations overlapping is one of the effective techniques used to implement the time-based strategy in today's era of global competition. Therefore, this technique has been studied extensively over the past few decades. In this paper, we first propose a uniquely categorized structure to characterize the existing lot streaming problems in terms of three main dimensions, seven subdimensions. and 17 levels. Then, a notation set is defined to systematically express each existing lot streaming problem by seven ordered elements corresponding to the seven subdimensions. Based on the classification structure and the defined notation set, a comprehensive survey is presented to make up for the lack of a literature review on this subject. The objective is to help the reader gain a clear understanding of the evolution of previous research on lot streaming. This paper concludes with some constructive suggestions for future research directions.[ABSTRACT FROM AUTHOR]
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Optimization of Maintenance Downtime for Handling equipment in a Container Terminal using Taguchi Scheme, Taguchi-Pareto Method and Taguchi-ABC Method
Get PDFThis paper examined the behavior of selected maintenance downtime parameters of handling equipment in a container terminal and established the system's optimal parameters. Taguchi method, Taguchi–Pareto method, and Taguchi–ABC method were applied to analyze it. The chosen process parameters are the downtime, probability density function, and cumulative density function. The L25, L25, and L20 orthogonal arrays were selected for the Taguchi, Taguchi-Pareto, and Taguchi–ABC methods. Data were acquired from a container terminal in the southern part of Nigeria, and we deployed the Weibull function to analyze the parameters at three shape functions of β = 0.5, 1, and 3 from twenty-five experiments. The signal–to–noise quotient and analysis of variance were used to establish the optimal level and contributions of the parameters. The results indicated that using the Taguchi method, for all the shape parameters of β = 0.5, 1, and 3, the most and the least significant parameters were downtime and cumulative density function, respectively. For the Taguchi-Pareto method, the most and the least significant parameters were downtime and probability density function, respectively, at β = 0.5. At β = 1, the most and the least significant parameters were downtime and cumulative density function, respectively. However, at β = 3, the most and the least significant parameters were probability density function and downtime, respectively. Finally, using the Taguchi-ABC method, at β = 0.5, the most and the least significant parameters were probability density function and downtime, respectively. Nonetheless, at β = 1 and 3, the most and the least significant parameters were downtime and probability density function, respectively. The proposed model would assist seaport maintenance managers in the effective control of downtim
On the equivalence of strong formulations for capacitated multi-level lot sizing problems with setup times
No full textSeveral mixed integer programming formulations have been proposed for modeling capacitated multi-level lot sizing problems with setup times. These formulations include the so-called facility location formulation, the shortest route formulation, and the inventory and lot sizing formulation with (l,S) inequalities. In this paper, we demonstrate the equivalence of these formulations when the integrality requirement is relaxed for any subset of binary setup decision variables. This equivalence has significant implications for decomposition-based methods since same optimal solution values are obtained no matter which formulation is used. In particular, we discuss the relax-and-fix method, a decomposition-based heuristic used for the efficient solution of hard lot sizing problems. Computational tests allow us to compare the effectiveness of different formulations using benchmark problems. The choice of formulation directly affects the required computational effort, and our results therefore provide guidelines on choosing an effective formulation during the development of heuristic-based solution procedures
Elephants and Optimality Again: SA-OT accounts for pronoun resolution in child language
No full textChildren display a surprising delay in correctly resolving pronouns, while they employ Chomsky's binding principles correctly in production and in resolving reflexives. We account for the mistakes as performance errors that are predicted by an Optimality Theoretical model implemented using simulated annealing (SA-OT). Our experiments suggest three novel explanations of the facts (see section 6). Additionally, the Optimality Theory-Harmony Grammar connection is also explored: the behaviour of the HG-based performance model converges to the OT-model if the base of the exponential weights grow large.The definitive version of this paper was published in Computational Linguistics in the Netherlands 2009, LOT Occasional Series 14.(2009) and is available at http://lotos.library.uu.nl/.Biró, T. (2009). Elephants and Optimality Again: SA-OT accounts for pronoun resolution in child language. In: B. Plank, and E.T.K. Sang, T. Cruys, (Eds.). Computational Linguistics in the Netherlands 2009. LOT Occasional Series 14. pp. 9-24. Utrecht: LOT.ISBN-13: 978-94-6093-004-1 (Published conference proceedings
LOT, a meso scale mechanistic tool for Porous Asphalt mixture design; winter damage and LOT validation
No full textBy assignment of the Centre for Transport and Navigation (DVS) of the Dutch Ministry of Transport, Public Works and Water Management the Delft University of Technology developed LOT. LOT is a Lifetime Optimisation Tool for Porous Asphalt, PA, based on meso scale structural modelling. LOT sees an asphalt mixture as a structure and computes stress and strain throughout that structure as a function of mixture component behaviour, mixture geometry, and mixture loading. This paper discusses the validation of LOT on the basis of full scale ravelling test. Further validation is achieved by analysis of winter damage which developed in PA during the Dutch 2008/2009 winter. For this analysis LOT simulations considering Long Term Aged (LTA) PA at temperatures of -10° to +20°C were made. The paper comes to the conclusion that meso scale mechanical models allow ravelling performance based mechanistic design of high performance PA mixtures.Geoscience & EngineeringCivil Engineering and Geoscience
Lot-sizing problem
Get PDFTitle: Lot-sizing problem Author: Ondřej Kafka Department: Department of probability and mathematical statistics Supervisor: RNDr. Martin Branda, Ph.D. Abstract: In the present work, we define the basic concepts of lot-sizing. We introduce Wagner-Whitin's dynamic lot size problem and derive a dynamic programming algorithm for the solution. Next we look at the case of PCLSP (Profit maximizing capacitated lot size problem) problem with fixed prices and negligable setup costs and solve it using specialized linear programming algorithm. Everything we try to explain with concrete examples. In the end we verify the efficiency of those algorithms by numerical study on random data comparing the performance of programmed algorithms with the professional optimization solver Gurobi. Keywords: Lot-sizing, dynamic programming, linear programmin
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