vii TABLE OF CONTENTS CHAPTER TITLE DECLARATION DEDICATION ACKNOWLEDGEMENT ABSTRACT ABSTRAK TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF ABBREVIATIONS LIST OF SYMBOLS LIST OF APPENDICES LIST OF ALGORITHMS 1 INTRODUCTION 1.1 Introduction 1.2 Motivations 1.3 Background of the Problem 1.4 Optimal Control Problem 1.5 Statement of the Problem 1.6 Objectives of the Research 1.7 Scope of the Research 1.8 Significance of the Study 1.9 Main Contributions 1.10 Thesis Overview 2 LITERATURE REVIEW 2.1 Introduction 2.2 Dynamic Optimization 2.3 Discretization Methods PAGE ii iii iv v vi vii x xi xiv xvi xviii xix 1 1 2 3 4 6 6 7 7 7 9 10 10 11 15 viii 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.14 Constraint Handling Methods System Integration Methods Global Optimization Methods Random Numbers Probability Direct Stochastic Methodology Steps for Development of PGSJ Probabilistic Tools Steps for Analyzing PGSJ Improvement and Comparisons Concluding Remarks 19 22 26 32 33 36 37 38 38 40 41 3 PROBABILISTIC GLOBAL SEARCH METHOD 3.1 Introduction 3.2 The PGSJ Algorithm 3.3 Convergence Analysis 3.4 Numerical Simulation 3.5 Complexity Analysis 3.6 Numerical Direct Strategies 3.7 Control Parameterization Framework 3.8 Implications of Constraints 3.9 Case Studies 3.10 Parameter Selection in PGSJ Algorithm 3.11 Concluding Remarks 42 42 43 55 60 63 64 65 66 66 74 78 4 CONTINUOUS ANT COLONY OPTIMIZATION 4.1 Introduction 4.2 Ant Colony Optimization 4.3 Continuous Ant Colony Optimization 4.4 Diversity in Ant Colony Optimization 4.5 Improvement on Ant Colony Optimization 4.6 Numerical Simulations 4.7 Concluding Remarks 79 79 80 82 85 88 91 102 5 ANALYSIS OF RESULTS AND DISCUSSION 5.1 Introduction 5.2 Comparisons 5.3 Discussions 103 103 103 114 ix 5.4 5.5 5.6 6 Improvements A Practical Problem Concluding Remarks CONCLUSION 6.1 Introduction 6.2 Summary of the Thesis 6.3 Directional Future Research 116 121 125 130 130 130 133 REFERENCES 134 Appendix A 151 x LIST OF TABLES TABLE NO. 2.1 3.1 3.2 3.3 4.1 5.1 5.2 TITLE Some trial parameters and their corresponding value of performance index regarding Problem (1.3) The algorithm inputs functions and parameters Results of testing PGSJ with several benchmark problems Solution of Example 3.2 using BCP/PGSJ method Comparing the performance of ACO family The performance of PGSJ, PGSJ-LS1, PGSJ-LS2, and PGSJ-LS3 based on the iterative solutions The performance of PGSJ, PGSJ-LS1, PGSJ-LS2, and PGSJ-LS3 based on the number of function evaluations PAGE 17 46 62 70 96 118 119 xi LIST OF FIGURES FIGURE NO. 1.1 2.1 2.2 2.3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 TITLE An illustration of a tunnel-diode oscillator Illustration of the control graphs corresponding to some parameters regarding Problem (1.3) The chart of available approaches for the solution of constrained OCPs An illustration of the direct methodology used in this study A uniform pdf when N = 5, and the domain of the pdf is [2.5, 5] An illustration of a general pdf when N = 5, and the domain of the pdf is [2.5, 5] An illustration of a pdf after bisecting when N = 5, and the domain of the pdf is [2.5, 5] The PGSJ flowchart The search space Initialization Uniform pdf pdf-updating Continuing pdf-updating Bisecting Continuing the bisecting The second iteration pdf-updating Continuing pdf-updating Bisecting The third iteration The number of the function evaluations while the dimension is increased The graph of optimal control for Example 3.1. The graph of error between exact and computational control for Example 3.1. PAGE 5 18 35 39 45 45 48 51 52 52 52 52 53 53 54 54 54 54 54 54 64 68 68 xii 3.20 3.21 3.22 3.23 3.24 3.25 3.26 3.27 3.28 3.29 3.30 4.1 4.2 4.3 4.4 4.5 4.6 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 5.12 The graph of state variables for Example 3.1. The graph of optimal control for Example 3.2. The graph of state variables for Example 3.2. The optimal control for Example 3.3 The optimal value for state variable x1 for Example 3.3 The graph of the constraint for Example 3.3 The optimal control for Example 3.4 The optimal value for state variable x1 for Example 3.4 The optimal value for state variable x2 for Example 3.4 The optimal value for state variable x3 for Example 3.4 The graph of the constraint for Example 3.4 Performance of the ACOR algorithm on example 3.1 Solution of example 3.1 using ACOR algorithm Performance of the DACOR algorithm on example 3.1 Solution of example 3.1 using DACOR algorithm Performance of the IACOR -LS algorithm on example 3.1 Solution of example 3.1 using IACOR -LS algorithm The performance of the pdf–based algorithms against the exact solution on the solution of Example 3.1 The state variable x1 (t) obtained by the pdf-based methods on the solution of Example 3.1 Solution of Example 3.1 using the pdf–based algorithms The performance of the pdf–based algorithms on the solution of Example 3.2 The state variable x2 (t) obtained by the pdf-based methods on the solution of Example 3.2 The state variable x1 (t) obtained by the pdf-based methods on the solution of Example 3.2 Solution of Example 3.2 using the pdf-based algorithms The performance of the pdf–based algorithms on the solution of Example 3.3 Solution of Example 3.3 using the pdf-based algorithms The constraint of Example 3.3 obtained by the pdf–based algorithms The state variable x1 (t) obtained by the pdf-based methods on the solution of Example 3.3 The state variable x2 (t) obtained by the pdf-based methods on the solution of Example 3.3 69 71 71 73 74 75 75 76 76 77 77 98 99 99 100 101 101 104 104 105 106 106 107 107 108 108 109 109 110 xiii 5.13 5.14 5.15 5.16 5.17 5.18 5.19 5.20 5.21 5.22 5.23 5.24 5.25 5.26 5.27 5.28 5.29 5.30 5.31 5.32 The state variable x4 (t) obtained by the pdf-based methods on the solution of Example 3.3 The state variable x5 (t) obtained by the pdf-based methods on the solution of Example 3.3 The performance of the pdf–based algorithms on the solution of Example 3.4 Solution of Example 3.4 using the pdf-based algorithms The constraint of Example 3.4 obtained by the pdf–based algorithms The state variable x1 (t) obtained by the pdf-based methods on the solution of Example 3.4 The state variable x2 (t) obtained by the pdf-based methods on the solution of Example 3.4 The state variable x4 (t) obtained by the pdf-based methods on the solution of Example 3.4 The iterative solutions used to evaluate the performance of PGSJ, PGSJ-LS1, PGSJ-LS2, and PGSJ-LS3 The iterative solutions used to evaluate the performance of PGSJ, PGSJ-LS1, PGSJ-LS2, and PGSJ-LS3 The performance of PGSJ, PGSJ-LS1, PGSJ-LS2, and PGSJ-LS3 based on the number of function evaluations The performance of PGSJ, PGSJ-LS1, PGSJ-LS2, and PGSJ-LS3 based on the number of function evaluations The control variable u1 (t) obtained by the PGSJ and PGSJLS methods on the solution of Problem (5.1) The control variable u2 (t) obtained by the PGSJ and PGSJLS methods on the solution of Problem (5.1) The state variable x5 (t) obtained by the PGSJ and PGSJ-LS methods on the solution of Problem (5.1) The state variable x1 (t) obtained by the PGSJ and PGSJ-LS methods on the solution of Problem (5.1) The state variable x2 (t) obtained by the PGSJ and PGSJ-LS methods on the solution of Problem (5.1) The state variable x3 (t) obtained by the PGSJ and PGSJ-LS methods on the solution of Problem (5.1) The state variable x4 (t) obtained by the PGSJ and PGSJ-LS methods on the solution of Problem (5.1) The state variable x6 (t) obtained by the PGSJ and PGSJ-LS methods on the solution of Problem (5.1) 110 111 111 112 112 113 113 114 120 120 120 124 125 126 126 127 127 128 128 129 xiv LIST OF ABBREVIATIONS ACO - Ant Colony Optimization ACK - Ackleys Problem ARS - Adaptive Random Search BB - Branch and Bound BC - Bee Colony BCP - Bernstein based control parameterization CRS - Controlled Random Search CM - Cosine Mixture Problem EA - Evolutionary Algorithms GA - Genetic Algorithm GARS - Generalized Adaptive Random Search GW - Griewank Problem HAS - Hesitant Adaptive Searches IDP - Iterative Dynamic Programming IVP - Initial Value Problem LHS - Latin Hypercube Sampling LM1 - Levy and Montalvo 1 Problem LM2 - Levy and Montalvo 2 Problem LMM - Linear Multistep Methods MS - Monkey Search NLP - Nonlinear Programming Problem NP - Nested Partitions NLP - Nonlinear Programming Problem OCP - Optimal Control Problem pdf - probability density function pdfs - probability density functions PGSJ - Probabilistic Global Search Johor PGSL - Probabilistic Global Search Lausanne xv PRS - Pure Random Searches PSO - Particle Swarm Optimization SA - Simulated Annealing SIN - Sinusoidal Problem SIVP - Stiff Initial Value Problem TS - Taylor Series xvi LIST OF SYMBOLS A - The acceptable probability density b - The number of bisecting procedure d - Dimension of the problem D - The box of feasible controls f - The objective function, H - Hamiltonian function Ini - The ith interval in the nth iteration Inij - The jth subinterval of the ith interval in the nth iteration M - Maximum number of iterations N - The number of partitions on each interval P - Probability of sampling from complementary search space S - The number of samples in each iteration t0 - Initial time tf - Final time u - The control curve u∗ - The optimal control curve x - The state variable - The optimal state variable ẋ - The first derivative of the state variable x0 - Initial value of the state variable Ω - The box of feasible region σ - The scale factor ϵ - The accuracy required ξ - Increment in probability updating procedure κ - The maximum number of updating iterations λ - Adjoint variable µ - Multiplier variable λ∗ - The optimal adjoint variable x ∗ xvii µ∗ - The optimal multiplier variable χ - The characteristic function Ωc - The Complementary search space π - Projection function xviii LIST OF APPENDICES APPENDIX A TITLE List of Publications PAGE 151 xix LIST OF ALGORITHMS ALGO. NO. 3.1 3.2 3.3 3.4 3.5 3.6 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 5.1 5.2 5.3 5.4 5.5 TITLE The sampling operator of PGSJ algorithm The pdf-updating operator of PGSJ algorithm The bisecting operator of PGSJ algorithm The Scaling operator of PGSJ algorithm The PGSJ algorithm The GARS algorithm The ACO framework The ACOR algorithm The construct solutions operator of the DACOR algorithm The DACOR algorithm The line search operator of the MTS-LS1 algorithm The MTS-LS1 algorithm The Line search operator of the IACOR -LS algorithm The construct solutions operator of the IACOR -LS algorithm The archive growth operator of the IACOR -LS algorithm The IACOR -LS algorithm The line search operator of the MTS-LS2 algorithm The MTS-LS2 algorithm The line search operator of the gaussian line search algorithm The gaussian line search algorithm The PGSJ–LS algorithm PAGE 47 47 49 49 50 56 81 86 88 89 91 92 92 93 93 94 116 117 121 122 123