• Title/Summary/Keyword: optimization procedure

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A New Green Clustering Algorithm for Energy Efficiency in High-Density WLANs

  • Lu, Yang;Tan, Xuezhi;Mo, Yun;Ma, Lin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.2
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    • pp.326-354
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    • 2014
  • In this paper, a new green clustering algorithm is proposed to be as a first approach in the framework of an energy efficient strategy for centralized enterprise high-density WLANs. Traditionally, in order to maintain the network coverage, all the APs within the WLAN have to be powered-on. Nevertheless, the new algorithm can power-off a large proportion of APs while the coverage is maintained as its always-on counterpart. The two main components of the new approach are the faster procedure based on K-means and the more accurate procedure based on Evolutionary Algorithm (EA), respectively. The two procedures are processes in parallel for different designed requirements and there is information interaction in between. In order to implement the new algorithm, EA is applied to handle the optimization of multiple objectives. Moreover, we adapt the method for selection and recombination, and then introduce a new operator for mutation. This paper also presents simulations in scenarios modeled with ray-tracing method and FDTD technique, and the results show that about 67% to 90% of energy consumption can be saved while it is able to maintain the original network coverage during periods when few users are online or the traffic load is low.

The Rearch of Stress Route for Concrete Structure using Advanced Progressive Optimization (개선된 점진적 구조 최적화 기법을 이용한 콘크리트 구조물의 응력경로 탐색)

  • Kim, Shi-Hwan;Yoon, Seong-Soo;Park, Jin-Seon;Jeon, Jeong-Bae
    • Journal of The Korean Society of Agricultural Engineers
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    • v.53 no.6
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    • pp.153-163
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    • 2011
  • This research describe improved algorithm that is able to decide terminal criterion of Evolutionary Structural Optimization (ESO), reducing load of calculation to search load path of concrete beam, and apply to agricultural facilities. The ESO method is that make to discrete structure, structural analyze each element stress through FEM. And repeat generation with next material condition to become for most suitable composing. Individual element introduces concept of zero stiffness, but zero stiffness decisions are gone to direction of exclusion. In this stduy, improve algorithm to be convergence by 'Rule of Alive or Die' in arrival because is most suitable. Also, existing terminal criterion lack consistency because that used depend on experience of researcher. This research procedure is fellowed. First, all modulus of elasticity assume a half of elasticity modulus of material, Second, structural analysis by FEM, Third, apply to the remove ratio and restoration ratio for the 'rule of alive or die'. Forth, reconstruct the element and material conditions. And repeat the first to forth process. The terminal time of evolutional procedure is the all elastic modulus of element changed to blank value or elasticity modulus value of original. Therefore, in this study, consist the algorithm for programming, and apply to the agricultural facilities with concrete.

A numerical and experimental approach for optimal structural section design of offshore aluminium helidecks

  • Seo, Jung Kwan;Park, Dae Kyeom;Jo, Sung Woo;Park, Joo Shin;Koo, Jeong Bon;Ha, Yeong Su;Jang, Ki Bok
    • Structural Engineering and Mechanics
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    • v.59 no.6
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    • pp.993-1017
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    • 2016
  • Helicopters are essential for supporting offshore oil and gas activities around the world. To ensure accessibility for helicopters, helideck structures must satisfy the safety requirements associated with various environmental and accidental loads. Recently, offshore helideck structures have used aluminium because of its light weight, low maintenance requirements, cost effectiveness and easy installation. However, section designs of aluminum pancakes tend to modify and/or change from the steel pancakes. Therefore, it is necessary to optimize section design and evaluate the safety requirements for aluminium helideck. In this study, a design procedure was developed based on section optimization techniques with experimental studies, industrial regulations and nonlinear finite element analyses. To validate and verify the procedure, a new aluminium section was developed and compared strength capacity with the existing helideck section profiles.

Application of meta-model based parameter identification of a seismically retrofitted reinforced concrete building

  • Yu, Eunjong
    • Computers and Concrete
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    • v.21 no.4
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    • pp.441-449
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    • 2018
  • FE models for complex or large-scaled structures that need detailed modeling of structural components are usually constructed using commercial analysis softwares. Updating of such FE model by conventional sensitivity-based methods is difficult since repeated computation for perturbed parameters and manual calculations are needed to obtain sensitivity matrix in each iteration. In this study, an FE model updating procedure avoiding such difficulties by using response surface (RS) method and a Pareto-based multiobjective optimization (MOO) was formulated and applied to FE models constructed with a commercial analysis package. The test building is a low-rise reinforced concrete building that has been seismically retrofitted. Dynamic properties of the building were extracted from vibration tests performed before and after the seismic retrofits, respectively. The elastic modulus of concrete and masonry, and spring constants for the expansion joint were updated. Two RS functions representing the errors in the natural frequencies and mode shape, respectively, were obtained and used as the objective functions for MOO. Among the Pareto solutions, the best compromise solution was determined using the TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) procedure. A similar task was performed for retrofitted building by taking the updating parameters as the stiffness of modified or added members. Obtained parameters of the existing building were reasonably comparable with the current code provisions. However, the stiffness of added concrete shear walls and steel section jacketed members were considerably lower than expectation. Such low values are seemingly because the bond between new and existing concrete was not as good as the monolithically casted members, even though they were connected by the anchoring bars.

A Study on the Improvement of Vehicle Ride Comfort by Genetic Algorithms (유전자 알고리즘을 이용한 차량 승차감 개선에 관한 연구)

  • 백운태;성활경
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.4
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    • pp.76-85
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    • 1998
  • Recently, Genetic Algorithm(GA) is widely adopted into a search procedure for structural optimization, which is a stochastic direct search strategy that mimics the process of genetic evolution. This methods consist of three genetics operations maned selection, crossover and mutation. Contrast to traditional optimal design techniques which use design sensitivity analysis results, GA, being zero-order method, is very simple. So, they can be easily applicable to wide area of design optimization problems. Also, owing to multi-point search procedure, they have higher probability of converge to global optimum compared to traditional techniques which take one-point search method. In this study, a method of finding the optimum values of suspension parameters is proposed by using the GA. And vehicle is modelled as planar vehicle having 5 degree-of-freedom. The generalized coordinates are vertical motion of passenger seat, sprung mass and front and rear unsprung mass and rotate(pitch) motion of sprung mass. For rapid converge and precluding local optimum, share function which distribute chromosomes over design bound is introduced. Elitist survival model, remainder stochastic sampling without replacement method, multi-point crossover method are adopted. In the sight of the improvement of ride comfort, good result can be obtained in 5-D.O.F. vehicle model by using GA.

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Refined optimal passive control of buffeting-induced wind loading of a suspension bridge

  • Domaneschi, M.;Martinelli, L.
    • Wind and Structures
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    • v.18 no.1
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    • pp.1-20
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    • 2014
  • Modern design of long suspension bridges must satisfy at the same time spanning very long distances and limiting their response against several external loads, even if of high intensity. Structural Control, with the solutions it provides, can offer a reliable contribution to limit internal forces and deformations in structural elements when extreme events occur. This positive aspect is very interesting when the dimensions of the structure are large. Herein, an updated numerical model of an existing suspension bridge is developed in a commercial finite element work frame, starting from original data. This model is used to reevaluate an optimization procedure for a passive control strategy, already proven effective with a simplified model of the buffeting wind forces. Such optimization procedure, previously implemented with a quasi-steady model of the buffeting excitation, is here reevaluated adopting a more refined version of the wind-structure interaction forces in which wind actions are applied on the towers and the cables considering drag forces only. For the deck a more refined formulation, based on the use of indicial functions, is adopted to reflect coupling with the bridge orientation and motion. It is shown that there is no variation of the previously identified optimal passive configuration.

A Study on the Hull Form Design with Minimum Resistance for Domestic Coastal Fishing Boats (국내 연안어선의 저항 최소화 선형설계에 관한 연구)

  • Kang, Dae-Sun;Yu, Jin-Won;Lee, Young-Gill
    • Journal of the Society of Naval Architects of Korea
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    • v.44 no.4
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    • pp.349-359
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    • 2007
  • In this study the hull form design with minimum resistance of domestic coastal fishing boat using a computer design procedure is carried out. The target boat is G/T 4.99 ton class fishing boat. which is one of the most popular boat in the coastal sea. For the task, the design parameters needed in preliminary stage are selected or determined from the existing boat. which has excellent resistances characteristics. In the EHP estimation during the design procedure, the main objective function is the hull resistance, and the initial hull forms before the optimization are selected from the boats that are in operation now. The EHP values from the hull after optimization process are also compared with those of the original hull to confirm its effect. Also, optimizing is investigated for the hull form to reestimate such factors as stability, laboring environment for the best design. it is expected that the results of this study here can be effectively used to improve the present design status of domestic small fishing boats.

Design of Rotman Lens for Curved Array Antenna with Minimal Phase Error (최소 위상 오차를 갖는 곡선 배열안테나용 Rotman 렌즈의 설계)

  • Park, Joo-Rae;Park, Dong-Chul
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.25 no.10
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    • pp.1077-1086
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    • 2014
  • We propose a design method of a Rotman lens for curved array antenna applicable to conformal array. In this paper, design equations are derived to obtain an array curve, transmission line lengths of a Rotman lens in conjunction with a curved array antenna, and the phase error of a Rotman lens based on these design equations is minimized through the beam curve optimization procedure and the refocusing procedure. Rotman lenses designed by the proposed design equations and design procedures still maintain 3 focal points, can feed a convex or concave array antenna with circular curve, parabolic curve, V-shaped curve, etc as well as a straight line array antenna, and have minimal phase error.

Methodology for Optimizing Parameters of Vehicle Safety Regulation on Pedestrian Protection (보행자-차량 충돌안전기준 매개변수 최적화 방법론 개발 및 적용)

  • Oh, Cheol;Kim, Beom-Il;Kang, Youn-Soo;Youn, Young-Han
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.5
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    • pp.186-194
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    • 2006
  • Traffic accident involved with the vulnerable pedestrian is one of the significant concerns, which has higher possibility of fatality than any other accident types. Worldwide significant efforts have been made to establish a vehicle safety regulation, which is internationally agreed, in order to reduce pedestrian casualties in pedestrian-vehicle collisions. One of the key issues in deriving the regulation is how to effectively select the parameter values associated with the regulation. This study firstly develops a method to optimize parameter values. An optimizing problem in terms of maximizing safety benefits, which are life-saving effects by the regulation, is formulated. Extensive actual accident data analysis and simulations are conducted to establish several statistical models to be used in the proposed optimization procedure. A set of parameter values that can produce maximizing life-saving effects is presented as the outcome of this study. It is expected that the proposed method would play a significant role in determining parameters as a decision support tool toward ensuring better pedestrian safety.

Calibration of Car-Following Models Using a Dual Genetic Algorithm with Central Composite Design (중심합성계획법 기반 이중유전자알고리즘을 활용한 차량추종모형 정산방법론 개발)

  • Bae, Bumjoon;Lim, Hyeonsup;So, Jaehyun (Jason)
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.18 no.2
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    • pp.29-43
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    • 2019
  • The calibration of microscopic traffic simulation models has received much attention in the simulation field. Although no standard has been established for it, a genetic algorithm (GA) has been widely employed in recent literature because of its high efficiency to find solutions in such optimization problems. However, the performance still falls short in simulation analyses to support fast decision making. This paper proposes a new calibration procedure using a dual GA and central composite design (CCD) in order to improve the efficiency. The calibration exercise goes through three major sequential steps: (1) experimental design using CCD for a quadratic response surface model (RSM) estimation, (2) 1st GA procedure using the RSM with CCD to find a near-optimal initial population for a next step, and (3) 2nd GA procedure to find a final solution. The proposed method was applied in calibrating the Gipps car-following model with respect to maximizing the likelihood of a spacing distribution between a lead and following vehicle. In order to evaluate the performance of the proposed method, a conventional calibration approach using a single GA was compared under both simulated and real vehicle trajectory data. It was found that the proposed approach enhances the optimization speed by starting to search from an initial population that is closer to the optimum than that of the other approach. This result implies the proposed approach has benefits for a large-scale traffic network simulation analysis. This method can be extended to other optimization tasks using GA in transportation studies.