• Title/Summary/Keyword: Objective Function

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SVQR with asymmetric quadratic loss function

  • Shim, Jooyong;Kim, Malsuk;Seok, Kyungha
    • Journal of the Korean Data and Information Science Society
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    • v.26 no.6
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    • pp.1537-1545
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    • 2015
  • Support vector quantile regression (SVQR) can be obtained by applying support vector machine with a check function instead of an e-insensitive loss function into the quantile regression, which still requires to solve a quadratic program (QP) problem which is time and memory expensive. In this paper we propose an SVQR whose objective function is composed of an asymmetric quadratic loss function. The proposed method overcomes the weak point of the SVQR with the check function. We use the iterative procedure to solve the objective problem. Furthermore, we introduce the generalized cross validation function to select the hyper-parameters which affect the performance of SVQR. Experimental results are then presented, which illustrate the performance of proposed SVQR.

A Feasibility Study of the IMRT Optimization with Pseudo-Biologic Objective Function (유사생물학적 대상 함수를 이용한 IMRT 최적화 알고리즘 가능성에 관한 연구)

  • Yi, Byong-Yong;Cho, Sam-Ju;Ahn, Seung-Do;Kim, Jong-Hoon;Choi, Eun-Kyung;Chang, Hye-Sook;Kwon, Soo-Il
    • Journal of Radiation Protection and Research
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    • v.26 no.4
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    • pp.417-424
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    • 2001
  • The pseudo-biologic objective function has been designed for the IMRT optimization. The RTP Tool Box (RTB) was used for this study. The pseudo-biologic function is similar to the biological objective function in mathematical shape, but uses physical parameters. The concepts of the TCI (Target Coverage Index) and the OSI (Organ Score Index) have been introduced for the target and the normal organs, respectively. The pseudo-biologic objective function s has been defined using these TCI and OSI's. The OSI's from the pseudo-biological function showed better results than from the physical functions, while TCI's showed similar tendency. These results revealed the feasibility of the pseudo-biologic function as an IMRT objective function.

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Multi-Objective Optimization Using Kriging Model and Data Mining

  • Jeong, Shin-Kyu;Obayashi, Shigeru
    • International Journal of Aeronautical and Space Sciences
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    • v.7 no.1
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    • pp.1-12
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    • 2006
  • In this study, a surrogate model is applied to multi-objective aerodynamic optimization design. For the balanced exploration and exploitation, each objective function is converted into the Expected Improvement (EI) and this value is used as fitness value in the multi-objective optimization instead of the objective function itself. Among the non-dominated solutions about EIs, additional sample points for the update of the Kriging model are selected. The present method was applied to a transonic airfoil design. Design results showed the validity of the present method. In order to obtain the information about design space, two data mining techniques are applied to design results: Analysis of Variance (ANOVA) and the Self-Organizing Map (SOM).

Application of multi objective genetic algorithm in ship hull optimization

  • Guha, Amitava;Falzaranoa, Jeffrey
    • Ocean Systems Engineering
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    • v.5 no.2
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    • pp.91-107
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    • 2015
  • Ship hull optimization is categorized as a bound, multi variable, multi objective problem with nonlinear constraints. In such analysis, where the objective function representing the performance of the ship generally requires computationally involved hydrodynamic interaction evaluation methods, the objective functions are not smooth. Hence, the evolutionary techniques to attain the optimum hull forms is considered as the most practical strategy. In this study, a parametric ship hull form represented by B-Spline curves is optimized for multiple performance criteria using Genetic Algorithm. The methodology applied to automate the hull form generation, selection of optimization solvers and hydrodynamic parameter calculation for objective function and constraint definition are discussed here.

ON THE CONVERGENCE OF THE UOBYQA METHOD

  • Han, Lixing;Liu, Guanghui
    • Journal of applied mathematics & informatics
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    • v.16 no.1_2
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    • pp.125-142
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    • 2004
  • We analyze the convergence properties of Powell's UOBYQA method. A distinguished feature of the method is its use of two trust region radii. We first study the convergence of the method when the objective function is quadratic. We then prove that it is globally convergent for general objective functions when the second trust region radius p converges to zero. This gives a justification for the use of p as a stopping criterion. Finally, we show that a variant of this method is superlinearly convergent when the objective function is strictly convex at the solution.

A Multi-Resource Leveling Algorithm for Project Networks

  • Lee, Chung-Ung
    • Journal of the military operations research society of Korea
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    • v.3 no.1
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    • pp.123-136
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    • 1977
  • This thesis presents a modification and extension to the Burgess and Killebrew heuristic resource leveling procedure for project networks. In contrast to previous algorithms appearing in the literature, the objective function of this algorithm. is the minimization of the sum of the squared errors in each time period (deviations around the mean usage) of all resources over the duration of the project. This objective function continues the search for an improved schedule beyond that of previous algorithms with their associated objective functions. One important feature is that the algorithm tends to reduce the number of periods that a resource is idle during its duration on the project.

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Model Structure and its Solution of Analytical Research on Transit Network Design (대중교통 노선망 설계에 관한 해석적 연구의 모형 구조와 풀이)

  • Park, Jun-Sik;Gwon, Yong-Seok
    • Journal of Korean Society of Transportation
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    • v.25 no.6
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    • pp.129-140
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    • 2007
  • The planning procedure of a transit operation consists of design, operation, and evaluation according to the research characteristics. There are some review studies on the operation and evaluation procedure, but the research on the design procedure has not yet been organized systematically. In this study, the research on transit system design was reviewed and the model structure and its solution method were arranged. The decision variables of the design procedure are network structure, line spacing or position, stop spacing, dispatching headway, and fleet size. In the analytical research on design procedure, system total cost is generally used as the objective function. System total cost is comprised of user cost, which is the sum of user access, waiting, and travel cost, and operating cost. Total cost of the transit system, used as the objective function, has the unique minimum because it is differentiable. There is a certain decision variable that makes the derivative of the objective function equal to zero and the second derivative of the objective function is positive. Therefore the decision variable that makes the first derivative of the objective function zero is the optimum that minimizes the objective function, and each of the cost components of the objective function become the same. This study is expected to help understanding about the research on the design procedure of transit operation planning and to help be a catalyst for relevant research.

Optimal Structural Design for Flexible Space Structure with Control System Based on LMI

  • Park, Jung-Hyen;Cho, Kyeum-Rae
    • Journal of Mechanical Science and Technology
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    • v.16 no.1
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    • pp.75-82
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    • 2002
  • A simultaneous optimal design problem of structural and control systems is discussed by taking a 3-D truss structure as an object. We use descriptor forms for a controlled object and a generalized plant because the structural parameters appear naturally in these forms. We consider a minimum weight design problem for structural system and disturbance suppression problem for the control system. The structural objective function is the structural weight and the control objective function is $H_{\infty}$ norm from the disturbance input to the controlled output in the closed-loop system. The design variables are cross sectional areas of the truss members. The conditions for the existence of controller are expressed in terms of linear matrix inequalities (LMI) By minimizing the linear sum of the normalized structural objective function and control objective function, it is possible to make optimal design by which the balance of the structural weight and the control performance is taken. We showed in this paper the validity of simultaneous optimal design of structural and control systems.

Evaluating Calibration Methods of Stream Flow for Water Quality Management (수질학적 관점에서의 수문모델 유출량 보정 방법 평가)

  • Jeon, Ji-Hong;Choi, Donghyuk;Kim, Jung-Jin;Kim, Taedong
    • Journal of Korean Society on Water Environment
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    • v.25 no.3
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    • pp.432-440
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    • 2009
  • The effect of selecting hydrologic item for calculating objective function on calibration of stream flow was evaluated by Hydrologic Simulation Porgram-Fortran (HSPF) linked with Model Independent Parameter Optimizer (PEST). Daily and monthly stream flow and flow duration were used to calculate objective function. Automated calibration focused on monthly stream was proper to analyze seasonal or yearly water budget but not proper to predict daily stream flow or percent chance flow exceeded. Calibration result focused on flow duration is proper to predict precent chance flow exceeded but not proper to analyze water budget or predict peak flow. These results indicate that hydrologic item calculated for objective function on calibration procedure could influence calibration results and watershed modeler should select carefully hydrologic item for the purpose of model application. Current, the criteria of stream flow of Korean TMDL is generated based on percent chance flow exceeded, so flow duration should be included to calculate objective function on calibration procedure for the estimation of criteria of stream flow using hydrologic model.

Optimum Structural Design of D/H Tankers by using Pareto Optimal based Multi-objective function Method (Pareto 최적점 기반 다목적함수 기법에 의한 이중선각유조선의 최적 구조설계)

  • Na, Seung-Soo;Yum, Jae-Seon;Han, Sang-Min
    • Journal of the Society of Naval Architects of Korea
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    • v.42 no.3
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    • pp.284-289
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    • 2005
  • A structural design system is developed for the optimum design of double hull tankers based on the multi-objective function method. As a multi-objective function method, Pareto optimal based random search method is adopted to find the minimum structural weight and fabrication cost. The fabrication cost model is developed by considering the welding technique, welding poses and assembly stages to manage the fabrication man-hour and process. In this study, a new structural design is investigated due to the rapidly increased material cost. Several optimum structural designs on the basis of high material cost are carried out based on the Pareto optimal set obtained by the random search method. The design results are compared with existing ship, which is designed under low material cost.