• 제목/요약/키워드: Population Topology

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Elite-initial population for efficient topology optimization using multi-objective genetic algorithms

  • Shin, Hyunjin;Todoroki, Akira;Hirano, Yoshiyasu
    • International Journal of Aeronautical and Space Sciences
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    • 제14권4호
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    • pp.324-333
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    • 2013
  • The purpose of this paper is to improve the efficiency of multi-objective topology optimization using a genetic algorithm (GA) with bar-system representation. We proposed a new GA using an elite initial population obtained from a Solid Isotropic Material with Penalization (SIMP) using a weighted sum method. SIMP with a weighted sum method is one of the most established methods using sensitivity analysis. Although the implementation of the SIMP method is straightforward and computationally effective, it may be difficult to find a complete Pareto-optimal set in a multi-objective optimization problem. In this study, to build a more convergent and diverse global Pareto-optimal set and reduce the GA computational cost, some individuals, with similar topology to the local optimum solution obtained from the SIMP using the weighted sum method, were introduced for the initial population of the GA. The proposed method was applied to a structural topology optimization example and the results of the proposed method were compared with those of the traditional method using standard random initialization for the initial population of the GA.

새로운 위상 기반의 Particle Swarm Optimization 알고리즘 : 정보파급 PSO (A Modified Particle Swarm Optimization Algorithm : Information Diffusion PSO)

  • 박준혁;김병인
    • 대한산업공학회지
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    • 제37권3호
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    • pp.163-170
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    • 2011
  • This paper proposes a modified version of Particle Swarm Optimization (PSO) called Information Diffusion PSO (ID-PSO). In PSO algorithms, premature convergence of particles could be prevented by defining proper population topology. In this paper, we propose a variant of PSO algorithm using a new population topology. We draw inspiration from the theory of information diffusion which models the transmission of information or a rumor as one-to-one interactions between people. In ID-PSO, a particle interacts with only one particle at each iteration and they share their personal best solutions and recognized best solutions. Each particle recognizes the best solution that it has experienced or has learned from another particle as the recognized best. Computational experiments on the benchmark functions show the effectiveness of the proposed algorithm compared with the existing methods which use different population topologies.

유전자 알고리듬을 이용한 트러스/보 구조물의 기하학적 치수 및 토폴로지 최적설계에 관한 연구 (A study on the optimal sizing and topology design for Truss/Beam structures using a genetic algorithm)

  • 박종권;성활경
    • 한국정밀공학회지
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    • 제14권3호
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    • pp.89-97
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    • 1997
  • A genetic algorithm (GA) is a stochastic direct search strategy that mimics the process of genetic evolution. The GA applied herein works on a population of structural designs at any one time, and uses a structured information exchange based on the principles of natural selection and wurvival of the fittest to recombine the most desirable features of the designs over a sequence of generations until the process converges to a "maximum fitness" design. Principles of genetics are adapted into a search procedure for structural optimization. The methods consist of three genetics operations mainly named selection, cross- over and mutation. In this study, a method of finding the optimum topology of truss/beam structure is pro- posed by using the GA. In order to use GA in the optimum topology problem, chromosomes to FEM elements are assigned, and a penalty function is used to include constraints into fitness function. The results show that the GA has the potential to be an effective tool for the optimal design of structures accounting for sizing, geometrical and topological variables.variables.

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컴플라이언스 패턴 기반 유전자 알고리즘을 이용한 구조물 위상설계 (Structural Topology Design Using Compliance Pattern Based Genetic Algorithm)

  • 박영오;민승재
    • 대한기계학회논문집A
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    • 제33권8호
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    • pp.786-792
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    • 2009
  • Topology optimization is to find the optimal material distribution of the specified design domain minimizing the objective function while satisfying the design constraints. Since the genetic algorithm (GA) has its advantage of locating global optimum with high probability, it has been applied to the topology optimization. To guarantee the structural connectivity, the concept of compliance pattern is proposed and to improve the convergence rate, small number of population size and variable probability in genetic operators are incorporated into GA. The rank sum weight method is applied to formulate the fitness function consisting of compliance, volume, connectivity and checkerboard pattern. To substantiate the proposed method design examples in the previous works are compared with respect to the number of function evaluation and objective function value. The comparative study shows that the compliance pattern based GA results in the reduction of computational cost to obtain the reasonable structural topology.

Topology, shape, and size optimization of truss structures using modified teaching-learning based optimization

  • Tejani, Ghanshyam G.;Savsani, Vimal J.;Patel, Vivek K.;Bureerat, Sujin
    • Advances in Computational Design
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    • 제2권4호
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    • pp.313-331
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    • 2017
  • In this study, teaching-learning based optimization (TLBO) is improved by incorporating model of multiple teachers, adaptive teaching factor, self-motivated learning, and learning through tutorial. Modified TLBO (MTLBO) is applied for simultaneous topology, shape, and size optimization of space and planar trusses to study its effectiveness. All the benchmark problems are subjected to stress, displacement, and kinematic stability constraints while design variables are discrete and continuous. Analyses of unacceptable and singular topologies are prohibited by seeing element connectivity through Grubler's criterion and the positive definiteness. Performance of MTLBO is compared to TLBO and state-of-the-art algorithms available in literature, such as a genetic algorithm (GA), improved GA, force method and GA, ant colony optimization, adaptive multi-population differential evolution, a firefly algorithm, group search optimization (GSO), improved GSO, and intelligent garbage can decision-making model evolution algorithm. It is observed that MTLBO has performed better or found nearly the same optimum solutions.

3차원 공간 기반의 화재피난 시뮬레이션 시스템 개발 (A Development of Fire Evacuation Simulation System Based 3D Modeling)

  • 황연정;구원용;황은경;윤호주
    • 한국화재소방학회논문지
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    • 제25권6호
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    • pp.156-167
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    • 2011
  • 최근 건물의 대형화, 고층화, 복잡화가 이루어지고 있으며, 건축물 화재 발생건수와 이로 인한 인명 및 재산 피해의 증가함에 따라 화재피난 시뮬레이션을 통한 건축물의 안전성 점검의 필요성이 대두되고 있다. 따라서 본 연구에서는 외산 프로그램에 의존하고 있는 화재피난 시뮬레이션 분야에 한국인의 특성을 고려한 시뮬레이션 시스템을 구현하고자 하였다. 그 결과 3차원 공간 정보 기반으로 공간의 토폴로지를 생성하고, 피난 경로를 탐색하는 화재피난 시뮬레이션을 구축하였다.

An efficient genetic algorithm for the design optimization of cold-formed steel portal frame buildings

  • Phan, D.T.;Lim, J.B.P.;Tanyimboh, T.T.;Sha, W.
    • Steel and Composite Structures
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    • 제15권5호
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    • pp.519-538
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    • 2013
  • The design optimization of a cold-formed steel portal frame building is considered in this paper. The proposed genetic algorithm (GA) optimizer considers both topology (i.e., frame spacing and pitch) and cross-sectional sizes of the main structural members as the decision variables. Previous GAs in the literature were characterized by poor convergence, including slow progress, that usually results in excessive computation times and/or frequent failure to achieve an optimal or near-optimal solution. This is the main issue addressed in this paper. In an effort to improve the performance of the conventional GA, a niching strategy is presented that is shown to be an effective means of enhancing the dissimilarity of the solutions in each generation of the GA. Thus, population diversity is maintained and premature convergence is reduced significantly. Through benchmark examples, it is shown that the efficient GA proposed generates optimal solutions more consistently. A parametric study was carried out, and the results included. They show significant variation in the optimal topology in terms of pitch and frame spacing for a range of typical column heights. They also show that the optimized design achieved large savings based on the cost of the main structural elements; the inclusion of knee braces at the eaves yield further savings in cost, that are significant.

Performance Analysis of Multiple-Hop Wireless Body Area Network

  • Hiep, Pham Thanh;Hoang, Nguyen Huy;Kohno, Ryuji
    • Journal of Communications and Networks
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    • 제17권4호
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    • pp.419-427
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    • 2015
  • There have been increases in the elderly population worldwide, and this has been accompanied by rapid growth in the health-care market, as there is an ongoing need to monitor the health of individuals. Wireless body area networks (WBANs) consist of wireless sensors attached on or inside the human body to monitor vital health-related problems, e.g., electrocardiograms (ECGs), electroencephalograms (EEGs), and electronystagmograms (ENGs). With WBANs, patients' vital signs are recorded by each sensor and sent to a coordinator. However, because of obstructions by the human body, sensors cannot always send the data to the coordinator, requiring them to transmit at higher power. Therefore, we need to consider the lifetime of the sensors given their required transmit power. In the IEEE 802.15.6 standard, the transmission topology functions as a one-hop star plus one topology. In order to obtain a high throughput, we reduce the transmit power of the sensors and maintain equity for all sensors. We propose the multiple-hop transmission for WBANs based on the IEEE 802.15.6 carrier-sense multiple-access with collision avoidance (CSMA/CA) protocol. We calculate the throughput and variance of the transmit power by performing simulations, and we discuss the results obtained using the proposed theorems.

야생동물 생태학적 사례연구를 통해서 본 교량형 생태통로의 현황 및 문제점 (Ecological Case Study of Eco-bridges in Korea: State and Problem)

  • 최병진;조영석;정종철;김주필
    • 환경영향평가
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    • 제16권4호
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    • pp.285-300
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    • 2007
  • The purpose of this study was to ascertain the ecological state and problems of eco-bridges on Korean roads. The study was conducted from March to April 2007 by checking ecological factors and wildlife around the eco-bridges and habitats. 8 representative eco-bridges were selected by their bridge shape and condition of location. After field survey, we analyzed ideal trails for wildlife using field data, digital topology maps, satellite images, and land use map. In addition to trail analysis, we identified the propriety of the eco-bridges through Population Viability Analysis. Because of unsuitable location and management, we found that most of the bridges are not proper for wildlife dispersal. Moreover, in some habitats, we could expect that some local populations might be extinct without appropriate treatments.

Using the Topology of Large Scale Structure for Cosmological Parameter Estimation

  • Appleby, Stephen
    • 천문학회보
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    • 제43권2호
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    • pp.41.2-41.2
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    • 2018
  • The Minkowski Functionals of the matter densityeld, as traced by galaxies, contain information regarding the nature of dark energy and the fraction of dark matter in the Universe. In particular, the genus is a statistic that provides a clean measurement of the shape of the linear matter power spectrum. As the genus is a topological quantity, it is insensitive to galaxy bias and gravitational collapse. Furthermore, as it traces the linear matter power spectrum, it is a conserved quantity with redshift. Hence the genus amplitude is a standard population that can be used to test the distance-redshift relation. In this talk, I show how we can extract the genus from galaxy catalogs, and how we can use its properties to constrain the equation of state of dark energy and the energy content of the Universe.

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