Sequential Approximate Multiobjective Optimization Using Computational Intelligence SeriesEditor: JohannesJahn UniversityofErlangen-Nürnberg DepartmentofMathematics Martensstr.3 81058Erlangen Germany [email protected] Vector Optimization The series in Vector Optimization contains publications in various fields of opti- mization with vector-valued objective functions, such as multiobjective optimiza- tion, multi criteria decision making, set optimization, vector-valued game theory and border areas to financial mathematics, biosystems, semidefinite programming andmultiobjectivecontroltheory.Studiesofcontinuous,discrete,combinatorialand stochasticmultiobjectivemodelsininterestingfieldsofoperationsresearcharealso included.Theseriescoversmathematicaltheory,methodsandapplicationsineco- nomicsandengineering.ThesepublicationsbeingwritteninEnglishareprimarily monographsandmultipleauthorworkscontainingcurrentadvancesinthesefields. · · Hirotaka Nakayama Yeboon Yun Min Yoon Sequential Approximate Multiobjective Optimization Using Computational Intelligence 123 ProfessorHirotakaNakayama AssistantProfessorMinYoon Dept.ofIntelligenceandInformatics DivisionofMathematicalScience KonanUniversity PukyongNationalUniversity 8-9-1Okamoto,Higashinada 599Daeyeon3-dong,Nam-gu Kobe658-8501 Busan608-737 Japan Korea AssociateProfessorYeboonYun Dept.ofReliability-basedInformation SystemEngineering FacultyofEngineering KagawaUniversity 2217-20Hayashi-cho Takamatsu Kagawa761-0396 Japan ISBN978-3-540-88909-0 e-ISBN978-3-540-88910-6 DOI10.1007/978-3-540-88910-6 SpringerSeriesinVectorOptimizationISSN1867-8971 LibraryofCongressControlNumber:2008943999 (cid:2)c Springer-VerlagBerlinHeidelberg2009 Thisworkissubjecttocopyright.Allrightsarereserved,whetherthewholeorpartofthematerialis concerned,specificallytherightsoftranslation,reprinting,reuseofillustrations,recitation,broadcasting, reproductiononmicrofilmorinanyotherway,andstorageindatabanks.Duplicationofthispublication orpartsthereofispermittedonlyundertheprovisionsoftheGermanCopyrightLawofSeptember9, 1965,initscurrentversion,andpermissionforusemustalwaysbeobtainedfromSpringer.Violations areliabletoprosecutionundertheGermanCopyrightLaw. Theuseofgeneral descriptive names,registered names, trademarks, etc. inthis publication does not imply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfromtherelevantprotective lawsandregulationsandthereforefreeforgeneraluse. Coverdesign:WMXDesignGmbH,Heidelberg Printedonacid-freepaper springer.com Preface Manykindsofpracticalproblemssuchasengineeringdesign,industrialman- agement and financial investment have multiple objectives conflicting with eachother.Thoseproblemscanbeformulatedasmultiobjectiveoptimization. In multiobjective optimization, there does not necessarily a unique solution which minimizes (or maximizes) all objective functions. We usually face to the situation in which if we want to improve some of objectives, we have to give up other objectives. Finally, we pay much attention on how much to improve some of objectives and instead how much to give up others. This is called “trade-off.” Note that making trade-off is a problem of value judg- ment of decision makers. One of main themes of multiobjective optimization is how to incorporate value judgment of decision makers into decision sup- port systems. There are two major issues in value judgment (1) multiplicity of value judgment and (2) dynamics of value judgment. The multiplicity of value judgment is treated as trade-off analysis in multiobjective optimiza- tion. On the other hand, dynamics of value judgment is difficult to treat. However,itisnaturalthatdecisionmakerschangetheirvaluejudgmenteven in decision making process, because they obtain new information during the process. Therefore, decision support systems are to be robust against the change of value judgment of decision makers. To this aim, interactive pro- grammingmethodswhichsearchasolutionwhileelicitingpartialinformation on value judgment of decision makers have been developed. Those methods arerequiredtoperformflexiblyfordecisionmakers’attitude.Atearly1980s, many interactive programming methods for solving multiobjective optimiza- tion have been developed. Above all, the aspiration level approach to multi- objective programming problems has been widely recognized to be effective in many practical fields. Anothermajorissueisthatinmanypracticalproblems,inparticularinen- gineeringdesign,thefunctionformofcriteriaisnotgivenexplicitlyintermsof designvariables.Giventhevalueofdesignvariables,underthiscircumstance, the value of objective functions is obtained by real/computational experi- ments such as structural analysis, fluid mechanic analysis, thermodynamic v vi Preface analysis, and so on. Usually, these experiments are time consuming and ex- pensive. One of recent trends in optimization is how to treat these expensive criteria.Inordertomakethenumberoftheseexperimentsasfewaspossible, optimization is performed in parallel with predicting the form of objective functions.Thisiscalledsequentialapproximateoptimizationwithmetamod- eling. It has been observed that techniques of computational intelligence can be effectively applied for this purpose. Moreover, techniques of multiobjec- tive optimization themselves can also be applied to develop effective meth- odsincomputationalintelligence.Forexample,theauthorsdevelopedseveral kinds of support vector machines using multiobjective optimization and goal programming. Recently, researches of generating Pareto frontier are actively made. It is useful to visualize Pareto frontier, because decision makers can make trade- off analysis very easily on the shown figures of Pareto frontier. However, it is difficult to generate Pareto frontier in cases with more than two or three objectives. At this event, a method combining aspiration level approach and sequential approximate optimization using computational intelligence was proposed and recognized to be effective in many practical problems. This book describes those sophisticated methods for multiobjective opti- mization using computational intelligence along with real applications. This topicseemsquitenew.Nobookonthistopichasbeenseentoourknowledge inspiteofitsimportance.Thebookisself-containedandcomprehensive.The potential readers are researchers, practitioners in industries and students of graduate course and high grade of undergraduate course. Wehopethatthereadersofboththeoreticalresearchersandpractitioners canlearnthroughthisbookseveralmethodologiesonanewtrendofmultiob- jectiveoptimizationwhichisveryimportantandapplicableinmanypractical fields. Japan and Korea Hirotaka Nakayama November 2008 Yeboon Yun Min Yoon Contents List of Tables ................................................. xi List of Figures................................................ xiii 1 Basic Concepts of Multiobjective Optimization ........... 1 1.1 Mathematical Foundations............................... 1 1.2 Preference Order and Domination Set..................... 4 1.3 Scalarization........................................... 5 1.3.1 Linearly Weighted Sum ........................... 7 1.3.2 Tchebyshev Scalarization Function ................. 8 1.3.3 Augmented Tchebyshev Scalarization Function....... 8 1.3.4 Constraint Transformation Method ................. 10 1.4 Scalarization and Trade-off Analysis ...................... 11 2 Interactive Programming Methods for Multiobjective Optimization ............................................. 17 2.1 Goal Programming ..................................... 17 2.2 Why is the Weighting Method Ineffective? ................. 20 2.3 Satisficing Trade-off Method ............................. 22 2.3.1 On the Operation P .............................. 22 2.3.2 On the Operation T .............................. 24 2.3.3 Automatic Trade-off .............................. 25 2.3.4 Exact Trade-off .................................. 29 2.3.5 Interchange Between Objectives and Constraints ..... 29 2.3.6 Remarks on Trade-off for Objective Functions with 0-Sensitivity ................................ 30 2.3.7 Relationship to Fuzzy Mathematical Programming ... 32 2.4 Applications ........................................... 34 2.4.1 Feed Formulation for Live Stock.................... 34 2.4.2 Erection Management of Cable-Stayed Bridge........ 35 2.4.3 An Interactive Support System for Bond Trading..... 37 2.5 Some Remarks on Applications........................... 42 vii viii Contents 3 Generation of Pareto Frontier by Genetic Algorithms..... 45 3.1 Evolutionary Multiobjective Optimization ................. 45 3.1.1 Vector Evaluated Genetic Algorithm................ 46 3.1.2 Multiobjective Genetic Algorithm .................. 47 3.1.3 Elitist Nondominated Sorting Genetic Algorithm (NSGA-II) ...................................... 51 3.1.4 Strength Pareto Evolutionary Algorithm (SPEA2).... 53 3.2 Fitness Evaluation Using DEA ........................... 56 3.2.1 Quantitative Evaluation of Fitness.................. 56 3.2.2 Data Envelopment Analysis........................ 57 3.2.3 DEA Models..................................... 59 3.2.4 DEA Method .................................... 63 3.3 Fitness Evaluation Using GDEA ......................... 64 3.3.1 GDEA Model.................................... 64 3.3.2 GDEA Method .................................. 66 3.4 Comparisons of Several Fitness Evaluations................ 67 4 Multiobjective Optimization and Computational Intelligence ............................................... 73 4.1 Machine Learning ...................................... 73 4.1.1 Learning and Generalization ....................... 75 4.1.2 The Least Square Method ......................... 77 4.2 Radial Basis Function Networks .......................... 79 4.3 Support Vector Machines for Pattern Classification ......... 83 4.3.1 Hard Margin SVM ............................... 84 4.3.2 MOP/GP Approaches to Pattern Classification ...... 86 4.3.3 Soft Margin SVM ................................ 88 4.3.4 ν-SVM.......................................... 90 4.3.5 Extensions of SVM by MOP/GP ................... 90 4.3.6 Comparison of Experimental Results................ 96 4.4 Support Vector Machines for Regression................... 98 4.5 Combining Predetermined Model and SVR/RBFN.......... 110 5 Sequential Approximate Optimization .................... 113 5.1 Metamodels ........................................... 113 5.2 Optimal Design of Experiments .......................... 115 5.3 Distance-Based Criteria for Optimal Design................ 120 5.4 Incremental Design of Experiments ....................... 122 5.5 Kriging and Efficient Global Optimization ................. 126 5.5.1 Kriging and Prediction............................ 127 5.5.2 Efficient Global Optimization ...................... 133 5.6 Distance-Based Local and Global Information.............. 141 Contents ix 6 Combining Aspiration Level Approach and SAMO........ 151 6.1 Sequential Approximate Multiobjective Optimization Using Satisficing Trade-off Method ....................... 152 6.2 MCDM with Aspiration Level Method and GDEA.......... 159 6.3 Discussions ............................................ 167 7 Engineering Applications ................................. 169 7.1 Reinforcement of Cable-Stayed Bridges.................... 169 7.1.1 Dynamic Characteristics of Cable-Stayed Bridge...... 170 7.1.2 Discussions ...................................... 174 7.2 Multiobjective Startup Scheduling of Power Plants ......... 176 7.2.1 Startup Scheduling for Combined Cycle Power Plant.. 176 7.2.2 Sequential Approximate Multiobjective Optimization for Optimal Startup Scheduling .................... 178 7.2.3 Application Results............................... 179 7.2.4 Discussions ...................................... 183 References.................................................... 185 Index......................................................... 193
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