Alma Mater Studiorum - Universita` di Bologna DOTTORATO DI RICERCA IN Automatica e Ricerca Operativa Ciclo XXVIII Settoreconcorsualediafferenza: 01/A6-RICERCAOPERATIVA Settorescientificodisciplinare: MAT/09-RICERCAOPERATIVA Models and Solutions of Resource Allocation Problems based on Integer Linear and Nonlinear Programming Presentata da: Dimitri Thomopulos Coordinatore Dottorato Relatore Prof. Daniele Vigo Prof. Enrico Malaguti Correlatore Prof. Andrea Lodi Esame finale anno 2016 Contents 1 Introduction 1 1.1 On Resource Allocation Problems . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Thesis Contribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.3 Applied Motivations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.4 Thesis Methodological Outline . . . . . . . . . . . . . . . . . . . . . . . 6 1.4.1 Two-Dimensional Guillotine Cutting Problem . . . . . . . . . . . 6 1.4.2 Mid-Term Hydro Scheduling Problem . . . . . . . . . . . . . . . 7 2 Two-Dimensional Guillotine Cutting Problem 11 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.1.1 Families of cutting problems. . . . . . . . . . . . . . . . . . . . . 12 2.1.2 Structure of general guillotine cuts. . . . . . . . . . . . . . . . . . 13 2.1.3 Literature review. . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.1.4 Contribution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 2.2 MIP modeling of guillotine cuts . . . . . . . . . . . . . . . . . . . . . . . 16 2.2.1 Definition of the cut position set . . . . . . . . . . . . . . . . . . 20 2.2.2 Model extensions: Cutting Stock problem and Strip Packing problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.3 An effective solution procedure for the PP-G2KP Model . . . . . . . . . 27 2.3.1 Variable pricing procedures . . . . . . . . . . . . . . . . . . . . . 27 2.4 Computational Experiments . . . . . . . . . . . . . . . . . . . . . . . . . 29 2.4.1 Lower bound (feasible solution) computation . . . . . . . . . . . 32 2.4.2 Iterative Variable Pricing . . . . . . . . . . . . . . . . . . . . . . 34 2.4.3 Models size and reductions . . . . . . . . . . . . . . . . . . . . . 36 2.4.4 Overall solution procedure . . . . . . . . . . . . . . . . . . . . . . 41 2.4.5 Comparison with state-of-the-art approaches . . . . . . . . . . . 46 2.4.6 Relevance of guillotine cuts . . . . . . . . . . . . . . . . . . . . . 48 2.5 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 3 Mid-Term Hydro Scheduling Problem 51 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 3.1.1 Mid-term hydro scheduling . . . . . . . . . . . . . . . . . . . . . 54 3.1.2 Choice of the objective function . . . . . . . . . . . . . . . . . . . 55 3.2 Decomposition algorithm for nonlinear (CCP) . . . . . . . . . . . . . . . 56 3.2.1 Overview of the approach . . . . . . . . . . . . . . . . . . . . . . 58 3.2.2 Separation algorithm . . . . . . . . . . . . . . . . . . . . . . . . . 59 3.2.3 Termination of the Branch-and-Cut algorithm . . . . . . . . . . . 62 3.2.4 Comparison with generalized Benders cuts . . . . . . . . . . . . . 64 3.3 (CCP) for mid-term hydro scheduling . . . . . . . . . . . . . . . . . . . 66 3.3.1 Decomposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 3.3.1.1 Electricity generation function . . . . . . . . . . . . . . 68 3.3.1.2 Demand and price function . . . . . . . . . . . . . . . . 69 3.3.2 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 3.4 Computational experiments . . . . . . . . . . . . . . . . . . . . . . . . . 71 3.4.1 Implementation details . . . . . . . . . . . . . . . . . . . . . . . . 71 3.4.2 Computational performance . . . . . . . . . . . . . . . . . . . . . 73 3.4.3 Quadratic electricity generation function . . . . . . . . . . . . . . 80 3.4.4 The effect of α on the profit . . . . . . . . . . . . . . . . . . . . . 84 3.4.5 Other solvers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 3.5 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Bibliography 91 Keywords • Two-dimensional Cutting Problems • Guillotine Knapsack Problems • Chance Constrained Programming • Exact Algorithms • Integer Linear Programming • Nonlinear Programming • Pricing • Stochastic Programming • Computational Experiments Ai miei Genitori, mio Fratello, i miei Amici, i miei Nonni e in particolar modo a mio Nonno Dimitris Acknowledgements I want to express my deeply-felt thanks to my thesis advisors, Professors Enrico Malaguti and Andrea Lodi, for their warm encouragement, thoughtful guidance. I also want to express my gratitude to Dr.Valentina Cacchiani for her continuous support and sound advice. Lastly, I wish to thank Professor Daniele Vigo and Professor Giacomo Nannicini.
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