• Title/Summary/Keyword: Dynamic penalty

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A New Penalty Parameter Update Rule in the Augmented Lagrange Multiplier Method for Dynamic Response Optimization

  • Kim, Min-Soo;Choi, Dong-Hoon
    • Journal of Mechanical Science and Technology
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    • v.14 no.10
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    • pp.1122-1130
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    • 2000
  • Based on the value of the Lagrange multiplier and the degree of constraint activeness, a new update rule is proposed for penalty parameters of the ALM method. The theoretical exposition of this suggested update rule is presented by using the algorithmic interpretation and the geometric interpretation of the augmented Lagrangian. This interpretation shows that the penalty parameters can effect the performance of the ALM method. Also, it offers a lower limit on the penalty parameters that makes the augmented Lagrangian to be bounded. This lower limit forms the backbone of the proposed update rule. To investigate the numerical performance of the update rule, it is embedded in our ALM based dynamic response optimizer, and the optimizer is applied to solve six typical dynamic response optimization problems. Our optimization results are compared with those obtained by employing three conventional update rules used in the literature, which shows that the suggested update rule is more efficient and more stable than the conventional ones.

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Dynamic Contact of a Cantilever Beam with Rigid Wall Condition (강체벽과 충돌하는 외팔보의 진동)

  • Jang, Young-Ki;Kim, Jae-Ik;Kim, Kyu-Tae;Park, Nam-Gyu
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.11 s.104
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    • pp.1255-1261
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    • 2005
  • The dynamic contact model of a beam that contacts to a rigid wall in a reactor core was studied. The gap between the beam and contact wall results in dynamic contact accompanying inequality constraints. The inequality constraints can be relieved to an equality constraint problem by introducing a convex Penalty function. In this work, a beam with contact condition is formulated using quasi-convex penalty function and numerically solved. General coordinate solution is adopted to raise computational efficiency. Also nonlinearity is examined In the beam contacting to a rigid wall.

Multi-step design optimization of a high speed machine tool structure using a genetic algorithm with dynamic penalty (동적 벌점함수 유전 알고리즘과 다단계 설계방법을 이용한 공작기계 구조물의 설계 최적화)

  • 최영휴;배병태;김태형;박보선
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.108-113
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    • 2002
  • This paper presents a multi-step structural design optimization method fur machine tool structures using a genetic algorithm with dynamic penalty. The first step is a sectional topology optimization, which is to determine the best sectional construction that minimize the structural weight and the compliance responses subjected to some constraints. The second step is a static design optimization, in which the weight and the static compliance response are minimized under some dimensional and safety constraints. The third step is a dynamic design optimization, where the weight static compliance, and dynamic compliance of the structure are minimized under the same constraints. The proposed design method was examined on the 10-bar truss problem of topology and sizing optimization. And the results showed that our solution is better than or just about the same as the best one of the previous researches. Furthermore, we applied this method to the topology and sizing optimization of a crossbeam slider for a high-speed machining center. The topology optimization result gives the best desirable cross-section shape whose weight was reduced by 38.8% than the original configuration. The subsequent static and dynamic design optimization reduced the weight, static and dynamic compliances by 5.7 %, 2.1% and 19.1% respectively from the topology-optimized model. The examples demonstrated the feasibility of the suggested design optimization method.

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Simulation of Vehicle-Structure Dynamic Interaction by Displacement Constraint Equations and Stabilized Penalty Method (변위제한조건식과 안정화된 Penalty방법에 의한 차량 주행에 따른 구조물의 동적상호작용 해석기법)

  • Chung, Keun Young;Lee, Sung Uk;Min, Kyung Ju
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.4D
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    • pp.671-678
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    • 2006
  • In this study, to describe vehicle-structure dynamic interaction phenomena with 1/4 vehicle model, nonlinear Hertzian contact spring and nonlinear contact damper are adopted. The external loads acting on 1/4 vehicle model are selfweight of vehicle and geometry information of running surface. The constraint equation on contact surface is implemented by the Penalty method with stabilization and the reaction from constraint violation. To describe pitching motion of various vehicles two types of the displacement constraint equations are exerted to connect between car bodies and between bogie frames, i.e., the rigid body connection and the rigid body connection with pin, respectively. For the time integration of dynamic equations of vehicles and structure Newmark time integration scheme is adopted. To reduce the error caused by inadequate time step size, adaptive time-stepping technique is also adopted. Thus, it is expected that more versatile dynamic interaction phenomena can be described by this approach and it can be applied to various railway dynamic problems with low computational cost.

DEVELOPMENT OF AN IMPROVED THREE-DIMENSIONAL STATIC AND DYNAMIC STRUCTURAL ANALYSIS BASED ON FETI-LOCAL METHOD WITH PENALTY TERM

  • KIM, SEIL;JOO, HYUNSHIG;CHO, HAESEONG;SHIN, SANGJOON
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.21 no.3
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    • pp.125-142
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    • 2017
  • In this paper, development of the three-dimensional structural analysis is performed by applying FETI-local method. In the FETI-local method, the penalty term is added as a preconditioner. The OPT-DKT shell element is used in the present structural analysis. Newmark-${\beta}$ method is employed to conduct the dynamic analysis. The three-dimensional FETI-local static structural analysis is conducted. The contour and the displacement of the results are compared following the different number of sub-domains. The computational time and memory usage are compared with respect to the number of CPUs used. The three-dimensional dynamic structural analysis is conducted while applying FETI-local method. The present results show appropriate scalability in terms of the computational time and memory usage. It is expected to improve the computational efficiency by combining the advantages of the original FETI method, i.e., FETI-mixed using the mixed local-global Lagrange multiplier.

Traffic Flow Analysis by Delay Penalty and Road Pricing (지각패널티와 변동요금에 의한 교통류 분석 연구)

  • Byun, Wan-Hee;Kim, Ju-Hyun;Choi, Byun-Kuk;Song, Doo-Suk
    • Journal of Korean Society of Transportation
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    • v.23 no.6 s.84
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    • pp.71-80
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    • 2005
  • With rapid development Telematics industry, the concern of dynamic road pricing system is increasing. In this study, the change of traffic flows according to traffic information and variation of congestion road prices related to the dynamic road pricing was analyzed. In this study, three facts were unfolded. First, high delay penalty and low delay penalty drivers are shown different reaction for the different congestion road prices. Second, the higher congestion road prices the more drivers convert their route from toll road to non toll road. Third, high penalty drivers are converting to toll road than low delay penalty drivers under same congestion road prices. This study has reached the conclusion that dynamic congestion pricing has a high possibility for traffic management.

Structural Dynamic Optimization Using a Genetic Algorithm(GA) (유전자 알고리즘(GA)을 이용한 구조물의 동적해석 및 최적화)

  • 이영우;성활경
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.5
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    • pp.93-99
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    • 2000
  • In many dynamic structural optimization problems, the goal is to reduce the total weight of the structure without causing the resonance. Up to now, gradient informations(i.e., design sensitivity) have been used to achieve the goal. For some class of dynamic problems, especially coalescent eigenvalue Problems with multiobjective optimization, the design sensitivity analysis is too much complicated mathematically and numerically. Therefore, this article proposes a new technique fur structural dynamic modification using a mode modification method with Genetic Algorithm(GA). In GA formulation, fitness is defined based on penalty function approach. Design variables are iteratively improved by using genetic algorithm. Two numerical examples are shown, (ⅰ) a cantilevered plate, and (ⅱ) H-shaped structure. The results demonstrate that the proposed method is highly efficient.

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An Optimization Technique For Crane Acceleration Using A Genetic Algorithm (유전자알고리즘을 이용한 크레인가속도 최적화)

  • 박창권;김재량;정원지;홍대선;권장렬;박범석
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1701-1704
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    • 2003
  • This paper presents a new optimization technique of acceleration curve for a wafer transfer crane movement in which high speed and low vibration are desirable. This technique is based on a genetic algorithm with a penalty function for acceleration optimization under the assumption that an initial profile of acceleration curves constitutes the first generation of the genetic algorithm. Especially the penalty function consists of the violation of constraints and the number of violated constraints. The proposed penalty function makes the convergence rate of optimization process using the genetic algorithm more faster than the case of genetic algorithm without a penalty function. The optimized acceleration of the crane through the genetic algorithm and commercial dynamic analysis software has shown to have accurate movement and low vibration.

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Development of Genetic Algorithms for Efficient Constraints Handling (구속조건의 효율적인 처리를 위한 유전자 알고리즘의 개발)

  • Cho, Young-Suk;Choi, Dong-Hoon
    • Proceedings of the KSME Conference
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    • 2000.04a
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    • pp.725-730
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    • 2000
  • Genetic algorithms based on the theory of natural selection, have been applied to many different fields, and have proven to be relatively robust means to search for global optimum and handle discontinuous or even discrete data. Genetic algorithms are widely used for unconstrained optimization problems. However, their application to constrained optimization problems remains unsettled. The most prevalent technique for coping with infeasible solutions is to penalize a population member for constraint violation. But, the weighting of a penalty for a particular problem constraint is usually determined in the heuristic way. Therefore this paper proposes, the effective technique for handling constraints, the ranking penalty method and hybrid genetic algorithms. And this paper proposes dynamic mutation tate to maintain the diversity in population. The effectiveness of the proposed algorithm is tested on several test problems and results are discussed.

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Dynamic Contact of a Cantilever Beam with Rigid Wall Condition (강체벽과 충돌하는 한단이 고정된 외팔보의 진동)

  • Park, Nam-Gyu;Jang, Young-Ki;Kim, Jae-Ik;Kim, Kyu-Tae
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.436-439
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    • 2005
  • Dynamic contact of a cantilever beam with Sap at the end is discussed. The gap in a structure induces dynamic contact, and the contact problem is always accompanied by inequality constraints which mean that the solution of the structure with contact condition should satisfy variational inequality. Inequality, but, can be reduced to equality condition considering convex penalty function. In this paper, formulation of a beam with contact is derived using quasi convex penalty function. General coordinate solution which is needed to increase computational efficiency is applied. Nonlinear behavior of a beam with rigid and elastic contact condition was discussed.

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