• Title/Summary/Keyword: Position Optimization

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Large deflection of simple variable-arc-length beam subjected to a point load

  • Chucheepsakul, S.;Thepphitak, G.;Wang, C.M.
    • Structural Engineering and Mechanics
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    • v.4 no.1
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    • pp.49-59
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    • 1996
  • This paper considers large deflection problem of a simply supported beam with variable are length subjected to a point load. The beam has one of its ends hinged and at a fixed distance from this end propped by a frictionless support over which the beam can slide freely. This highly nonlinear flexural problem is solved by elliptic-integral method and shooting-optimization technique, thereby providing independent checks on the new solutions. Because the beam can slide freely over the frictionless support, there is a maximum or critical load which the beam can carry and it is dependent on the position of the load. Interestingly, two possible equilibrium configurations can be obtained for a given load magnitude which is less than the critical value. The maximum arc-length was found to be equal to about 2.19 times the fixed distance between the supports and this value is independent of the load position.

The optimal arrangement of RFID tags for mobile robot's position estimation (이동 로봇의 위치 추정을 위한 RFID Tag의 효율적 배치)

  • Song S.H.;Park H.H.;Moon S.W.;Ji Y.K.;Park J.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.10a
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    • pp.901-905
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    • 2005
  • It is very important to arrange landmarks when a mobile robot needs to measure its own location. So, it has been discussed often how to arrange landmarks in the optimal way until now. We, there, chose the RFID (Radio frequency Identification) tags as landmarks which can be observed by a mobile robot, and demonstrated the possibility of the optimal arrangement of them. For this work first, we defined the optimization problem and its parameters for the arrangement of tags. Second, we proposed the algorithm which can be applied to the optimization problem. Finally we could obtain closely optimal and practical arrangement with the minimum number of landmarks which satisfied the necessary condition by experimentation.

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Sinusoidal Map Jumping Gravity Search Algorithm Based on Asynchronous Learning

  • Zhou, Xinxin;Zhu, Guangwei
    • Journal of Information Processing Systems
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    • v.18 no.3
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    • pp.332-343
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    • 2022
  • To address the problems of the gravitational search algorithm (GSA) in which the population is prone to converge prematurely and fall into the local solution when solving the single-objective optimization problem, a sine map jumping gravity search algorithm based on asynchronous learning is proposed. First, a learning mechanism is introduced into the GSA. The agents keep learning from the excellent agents of the population while they are evolving, thus maintaining the memory and sharing of evolution information, addressing the algorithm's shortcoming in evolution that particle information depends on the current position information only, improving the diversity of the population, and avoiding premature convergence. Second, the sine function is used to map the change of the particle velocity into the position probability to improve the convergence accuracy. Third, the Levy flight strategy is introduced to prevent particles from falling into the local optimization. Finally, the proposed algorithm and other intelligent algorithms are simulated on 18 benchmark functions. The simulation results show that the proposed algorithm achieved improved the better performance.

Structural Design Optimization of Dynamic Crack Propagation Problems Using Peridynamics (페리다이나믹스를 이용한 균열진전 문제의 구조 최적설계)

  • Kim, Jae-Hyun;Park, Soomin;Cho, Seonho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.28 no.4
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    • pp.425-431
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    • 2015
  • Based on a bond-based peridynamics theory for dynamic crack propagation problems, this paper presents a design sensitivity analysis and optimization method. Peridynamics has a peculiar advantage over the existing continuum theory in the mathematical modelling of problems where discontinuities arise. For the design optimization of the crack propagation problems, a non-shape design sensitivity is derived using the adjoint variable method. The obtained adjoint sensitivity of displacement and strain energy turns out to be very accurate and efficient compared to the finite different sensitivity. The obtained design sensitivities are futher utilized to optimally control the position of bifurcation point in the design optimization of crack propagation in a plate under tension. A numerical experiment demonstrates that the optimal distribution of material density could delay the position of bifurcation.

Optimization of Position of Lightening Hole in 2D Structures through MLS basede Overset Metheod along with Genetic Algorithm (이동최소자승 중첩 격자 기법과 유전자 알고리듬을 이용한 2차원 구조물의 경감공 위치 최적 설계)

  • Oh, Min-Hwan;Woo, Dong-Ju;Cho, Jin-Yeon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.10
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    • pp.979-987
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    • 2008
  • In aerospace structural design, the position of lightening hole is often required to be optimized from the initial design in order to avoid an excessive stress concentration. To remodel the updated configuration in optimization procedure, re-meshing procedure is conventionally adopted. However, this approach is time-consuming, and has limitations especially in handling hexahedral or quadrilateral meshes, which are preferred because of their good numerical performances. To attenuate these disadvantages, new optimization scheme is proposed by combining the MLS(Moving Least Squares) based overset method and the genetic algorithm in this work. To test the validity of the proposed optimization scheme, optimizations of positions of lightening holes in 2D structures have been carried out.

Study on Analysis of Website Visibiliy for Search Engine Optimization (검색엔진 최적화를 위한 웹사이트 가시성 분석에 관한 연구)

  • Yoon, Sun-Hee
    • Journal of the Korea Society of Computer and Information
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    • v.15 no.6
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    • pp.147-152
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    • 2010
  • The Internet has become a major channel of business marketing and sales, and there is a core competitive object between websites for a high position ranking in search engine results. There are various ways to maintain the high position ranking of website involving the development of componental coding or the expensive investment for the search engine optimization. The purpose of this paper is proposed to identify and rank the negative elements of website visibility to get rid of those elements when website designer designs the webpage. Website can be removed from indices of search engines when they are not satisfied for search engine optimization. The proposed experiments that are identified and ranked the negative elements of website visibility in this paper are based on the theories and experiments of existing website visibility models. The experimental analyses in this paper are scored and normalized based on methodologies of those models and 10 highest negative elements are ranked through the analyses. Therefore when website is designed, these highest negative elements should be avoided so website can not be removed in the indices of search engines.

Validation of Fresh-Saltwater Sharp-Interface Model Using Freshwater Lens Hydraulic Experiment (담수렌즈 수리모형을 이용한 담수-염수 경계면 수치모델의 검정)

  • Hong, Sung Hun;Park, Namsik
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.3B
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    • pp.263-269
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    • 2006
  • An optimization model was developed for groundwater development and management in coastal areas. The optimization model consists of coastal groundwater flow model and optimization techniques. The objective of this work is to validate sharp-interface model which is one of major components of the optimization model. A laboratory experimental model is built to simulate freshwater lens, i.e., layer of freshwater floating on top of saltwater, phenomena. Experimental results for the position of fresh-saltwater sharp-interface and the salinity in well are compared with numerical results. Average ratio of relative error is estimated approximately between 2.91% and 4.39%. And the numerical results are in good agreement with the laboratory results of water quality in well in addition to the position of sharp-interface. Accordingly the evaluation of coastal groundwater flow using sharp-interface model can produce reasonable results.

Optimal Positioning of Heating Lines in a Compression Molding Die Using the Boundary Element Method (경계요소법을 이용한 압축성형다이 가열선의 최적위치 설계)

  • 이부윤;조종래
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.6
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    • pp.1478-1485
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    • 1993
  • A shape optimization problem is formulated to determine the optimal position of heating lines in a compression molding die. The objective of the problem is that the cavity surface would be maintained by a prescribed uniform temperature. A boundary integral equation for the sensitivity of the temperature in terms of hole position is derived using the method of shape design sensitivity analysis. The boundary element method is employed to analyze the temperature and sensitivity field of the die. The sensitivity calculation algorithm is incorporated in an optimization routine. To demonstrate a numerical implementation, an example problem arising in thermal design of a compression molding die is dealt with, showing that the number of heating lines chosen for the die strongly affects the ultimate uniformity of the cavity surface temperature.

A Smart Setup for Craniospinal Irradiation

  • Peterson, Jennifer L.;Vallow, Laura A.;Kim, Siyong;Casale, Henry E.;Tzou, Katherine S.
    • Progress in Medical Physics
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    • v.24 no.4
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    • pp.230-236
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    • 2013
  • Our purpose is to present a novel technique for delivering craniospinal irradiation in the supine position using a perfect match, field-in-field (FIF) intrafractional feathering, and simple forward-optimization technique. To achieve this purpose, computed tomography simulation was performed with patients in the supine position. Half-beam, blocked, opposed, lateral, cranial fields with a collimator rotation were matched to the divergence of the superior border of an upper-spinal field. Fixed field parameters were used, and the isocenter of the upper-spinal field was placed at the same source-to-axis distance (SAD), 20 cm inferior to the cranial isocenter. For a lower-spinal field, the isocenter was placed 40 cm inferior to the cranial isocenter at a constant SAD. Both gantry and couch rotations for the lower-spinal field were used to achieve perfect divergence match with the inferior border of the upper-spinal field. A FIF technique was used to feather the craniospinal and spinal-spinal junction daily by varying the match line over 2 cm. The dose throughout the target volume was modulated using the FIF simple forward optimization technique to obtain homogenous coverage. Daily, image-guided therapy was used to assure and verify the setup. This supine-position, perfect match craniospinal irradiation technique with FIF intrafractional feathering and dose modulation provides a simple and safe way to deliver treatment while minimizing dose inhomogeneity.

Optimum design of steel framed structures including determination of the best position of columns

  • Torkzadeh, P.;Salajegheh, J.;Salajegheh, E.
    • Steel and Composite Structures
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    • v.8 no.5
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    • pp.343-359
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    • 2008
  • In the present study, an efficient method for the optimum design of three-dimensional (3D) steel framed structures is proposed. In this method, in addition to choosing the best position of columns based on architectural requirements, the optimum cross-sectional dimensions of elements are determined. The preliminary design variables are considered as the number of columns in structural plan, which are determined by a direct optimization method suitable for discrete variables, without requiring the evaluation of derivatives. After forming the geometry of structure, the main variables of the cross-sectional dimensions are evaluated, which satisfy the design constraints and also achieve the least-weight of the structure. To reduce the number of finite element analyses and the overall computational time, a new third order approximate function is introduced which employs only the diagonal elements of the higher order derivatives matrices. This function produces a high quality approximation and also, a robust optimization process. The main feature of the proposed techniques that the higher order derivatives are established by the first order exact derivatives. Several examples are solved and efficiency of the new approximation method and also, the proposed method for the best position of columns in 3D steel framed structures is discussed.