• Title, Summary, Keyword: discrete optimization

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Development of an Optimization Algorithm Using Orthogonal Arrays in Discrete Space (직교배열표를 이용한 이산공간에서의 최적화 알고리즘 개발)

  • Yi, Jeong-Wook;Park, Joon-Seong;Lee, Kwon-Hee;Park, Gyung-Jin
    • Proceedings of the KSME Conference
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    • pp.408-413
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    • 2001
  • The structural optimization is carried out in the continuous design space or discrete design space. Methods for discrete variables such as genetic algorithms are extremely expensive in computational cost. In this research, an iterative optimization algorithm using orthogonal arrays is developed for design in discrete space. An orthogonal array is selected on a discrete design space and levels are selected from candidate values. Matrix experiments with the orthogonal array are conducted. New results of matrix experiments are obtained with penalty functions for constraints. A new design is determined from analysis of means(ANOM). An orthogonal array is defined around the new values and matrix experiments are conducted. The final optimum design is found from iterative process. The suggested algorithm has been applied to various problems such as truss and frame type structures. The results are compared with those from a genetic algorithm and discussed.

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Discrete Optimization of Structural System by Using the Harmony Search Heuristic Algorithm with Penalty Function (벌칙함수를 도입한 하모니서치 휴리스틱 알고리즘 기반 구조물의 이산최적설계법)

  • Jung, Ju-Seong;Choi, Yun-Chul;Lee, Kang-Seok
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.33 no.12
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    • pp.53-62
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    • 2017
  • Many gradient-based mathematical methods have been developed and are in use for structural size optimization problems, in which the cross-sectional areas or sizing variables are usually assumed to be continuous. In most practical structural engineering design problems, however, the design variables are discrete. The main objective of this paper is to propose an efficient optimization method for structures with discrete-sized variables based on the harmony search (HS) meta-heuristic algorithm that is derived using penalty function. The recently developed HS algorithm was conceptualized using the musical process of searching for a perfect state of harmony. It uses a stochastic random search instead of a gradient search so that derivative information is unnecessary. In this paper, a discrete search strategy using the HS algorithm with a static penalty function is presented in detail and its applicability using several standard truss examples is discussed. The numerical results reveal that the HS algorithm with the static penalty function proposed in this study is a powerful search and design optimization technique for structures with discrete-sized members.

Workload Allocation Methods in Discrete Manufacturing Systems:Model and Optimization

  • Yingwen, Zheng
    • 제어로봇시스템학회:학술대회논문집
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    • pp.1362-1366
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    • 2003
  • Workload programming is allocating suitable workloads of production process according to the needs of products, which would minimize the total cost of both work and stock under some constraint conditions. In this paper, a production process flow chart of discrete manufacturing is presented by a Petri net, and the optimization model of workload-stock is established. An approach of the optimal workloads is provided by means of the integer matrix theory. An example is given to verify this method.

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Structured Static Output Feedback Stabilization of Discrete Time Linear Systems (구조적인 제약이 있는 이산시간 선형시스템의 정적출력 되먹임 안정화 제어기 설계)

  • Lee, Joonhwa
    • Journal of Institute of Control, Robotics and Systems
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    • v.21 no.3
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    • pp.233-236
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    • 2015
  • In this paper, a nonlinear optimization problem is proposed to obtain a structured static output feedback controller for discrete time linear systems. The proposed optimization problem has LMI (Linear Matrix Inequality) constraints and a non-convex objective function. Using the conditional gradient method, we can obtain suboptimal solutions of the proposed optimization problem. Numerical examples show the effectives of the proposed approach.

Discrete bacterial foraging optimization for resource allocation in macrocell-femtocell networks

  • Lalin, Heng;Mustika, I Wayan;Setiawan, Noor Akhmad
    • ETRI Journal
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    • v.40 no.6
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    • pp.726-735
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    • 2018
  • Femtocells are good examples of the ultimate networking technology, offering enhanced indoor coverage and higher data rate. However, the dense deployment of femto base stations (FBSs) and the exploitation of subcarrier reuse between macrocell base stations and FBSs result in significant co-tier and cross-tier interference, thus degrading system performance. Therefore, appropriate resource allocations are required to mitigate the interference. This paper proposes a discrete bacterial foraging optimization (DBFO) algorithm to find the optimal resource allocation in two-tier networks. The simulation results showed that DBFO outperforms the random-resource allocation and discrete particle swarm optimization (DPSO) considering the small number of steps taken by particles and bacteria.

Simulation Study of Discrete Event Systems using Fast Approximation Method of Single Run and Optimization Method of Multiple Run (단일 실행의 빠른 근사해 기법과 반복 실행의 최적화 기법을 이용한 이산형 시스템의 시뮬레이션 연구)

  • Park, Kyoung Jong;Lee, Young Hae
    • Journal of Korean Institute of Industrial Engineers
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    • v.32 no.1
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    • pp.9-17
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    • 2006
  • This paper deals with a discrete simulation optimization method for designing a complex probabilistic discrete event simulation. The developed algorithm uses the configuration algorithm that can change decision variables and the stopping algorithm that can end simulation in order to satisfy the given objective value during single run. It tries to estimate an auto-regressive model for evaluating correctly the objective function obtained by a small amount of output data. We apply the proposed algorithm to M/M/s model, (s, S) inventory model, and known-function problem. The proposed algorithm can't always guarantee the optimal solution but the method gives an approximate feasible solution in a relatively short time period. We, therefore, show the proposed algorithm can be used as an initial feasible solution of existing optimization methods that need multiple simulation run to search an optimal solution.

Reasonable Optimum Design of Agricultural Reinforced Concrete Structure - Superstructures of Aqueduct - (농업용 철근콘크리트 구조물의 합리적인 최적설계 -수로교 상부구조물-)

  • Kim, Jong-Ok;Park, Chan-Gi;Cha, Sang-Sun
    • Journal of The Korean Society of Agricultural Engineers
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    • v.52 no.5
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    • pp.19-26
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    • 2010
  • This study was conducted to find out the reasonable optimum design method of agricultural reinforced concrete structures. Selected design variables are the dimension of concrete section, reinforced steel area, and objective function is formulated by cost function. To test the reliability, efficiency, possibility of application and reasonability of optimum design method, both continuous optimization method and mixed-discrete optimization method were applied to the design of reinforced concrete superstructure of aqueduct and application results were discussed. It is proved that mixed-discrete optimization method is more reliable, efficient and reasonable than continuous optimization method for the optimum design of reinforced concrete agricultural structures.

Reasonable Optimum Design of Prestressed Concrete Structures (프리스트레스트 콘크리트 구조물의 합리적인 최적설계)

  • Kim, Jong-Ok
    • Journal of The Korean Society of Agricultural Engineers
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    • v.46 no.2
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    • pp.77-89
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    • 2004
  • This study was carried out to find out the reasonable optimum design method for the design of prestressed concrete structures. The optimum design problems were formulated and computer programs to solve these problems were developed. To test the reliablity, efficiency, possibility of application and reasonablity of optimum design problems and computer programs, both continuous optimization method and mixed-discrete optimization method were applied to the design of prestressed concrete composite girder and application results were discussed. It is proved that mixed-discrete optimization method is more reliable, efficient and reasonable than continuous optimization method for the optimum design of prestressed concrete structures.

Structural Optimization Using Tabu Search in Discrete Design Space (타부탐색을 이용한 이산설계공간에서의 구조물의 최적설계)

  • Lee, Kwon-Hee;Joo, Won-Sik
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.5
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    • pp.798-806
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    • 2003
  • Structural optimization has been carried out in continuous or discrete design space. Methods for continuous design have been well developed though they are finding the local optima. On the contrary, the existing methods for discrete design are extremely expensive in computational cost or not robust. In this research, an algorithm using tabu search is developed fur the discrete structural designs. The tabu list and the neighbor function of the Tabu concepts are introduced to the algorithm. It defines the number of steps, the maximum number for random searches and the stop criteria. A tabu search is known as the heuristic approach while genetic algorithm and simulated annealing algorithm are attributed to the stochastic approach. It is shown that an algorithm using the tabu search with random moves has an advantage of discrete design. Furthermore, the suggested method finds the reliable optimum for the discrete design problems. The existing tabu search methods are reviewed. Subsequently, the suggested method is explained. The mathematical problems and structural design problems are investigated to show the validity of the proposed method. The results of the structural designs are compared with those from a genetic algorithm and an orthogonal array design.

Local Solution of a Sequential Algorithm Using Orthogonal Arrays in a Discrete Design Space (이산설계공간에서 직교배열표를 이용한 순차적 알고리듬의 국부해)

  • Yi, Jeong-Wook;Park, Gyung-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.9
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    • pp.1399-1407
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    • 2004
  • Structural optimization has been carried out in continuous design space or in discrete design space. Generally, available designs are discrete in design practice. However, the methods for discrete variables are extremely expensive in computational cost. An iterative optimization algorithm is proposed for design in a discrete space, which is called a sequential algorithm using orthogonal arrays (SOA). We demonstrate verifying the fact that a local optimum solution can be obtained from the process with this algorithm. The local optimum solution is defined in a discrete design space. Then the search space, which is a set of candidate values of each design variables formed by the neighborhood of a current design point, is defined. It is verified that a local optimum solution can be found by sequentially moving the search space. The SOA algorithm has been applied to problems such as truss type structures. Then it is confirmed that a local solution can be obtained by using the SOA algorithm