• Title/Summary/Keyword: Local Solution

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Optimized Local Relocation for VLSI Circuit Modification Using Mean-Field Annealing

  • Karimi, Gholam Reza;Verki, Ahmad Azizi;Mirzakuchaki, Sattar
    • ETRI Journal
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    • v.32 no.6
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    • pp.932-939
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    • 2010
  • In this paper, a fast migration method is proposed. Our method executes local relocation on a model placement where an additional module is added to it for modification with a minimum number of displacements. This method is based on mean-field annealing (MFA), which produces a solution as reliable as a previously used method called simulated annealing. The proposed method requires substantially less time and hardware, and it is less sensitive to the initial and final temperatures. In addition, the solution runtime is mostly independent of the size and complexity of the input model placement. Our proposed MFA algorithm is optimized by enabling module rotation inside an energy function called permissible distances preservation energy. This, in turn, allows more options in moving the engaged modules. Finally, a three-phase cooling process governs the convergence of problem variables called neurons or spins.

OPTIMIZATION MODEL AND ALGORITHM OF THE TRAJECTORY OF HORIZONTAL WELL WITH PERTURBATION

  • LI AN;FENG ENMIN
    • Journal of applied mathematics & informatics
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    • v.20 no.1_2
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    • pp.391-399
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    • 2006
  • In order to solve the optimization problem of designing the trajectory of three-dimensional horizontal well, we establish a multi-phase, nonlinear, stochastic dynamic system of the trajectory of horizontal well. We take the precision of hitting target and the total length of the trajectory as the performance index. By the integration of the state equation, this model can be transformed into a nonlinear stochastic programming. We discuss here the necessary conditions under which a local solution exists and depends in a continuous way on the parameter (perturbation). According to the properties we propose a revised Hooke-Jeeves algorithm and work out corresponding software to calculate the local solution of the nonlinear stochastic programming and the expectancy of the performance index. The numerical results illustrate the validity of the proposed model and algorithm.

Ant Colony System for Vehicle Routing Problem with Simultaneous Delivery and Pick-up under Time Windows (시간제약하 배달과 수거를 동시에 수행하는 차량경로문제를 위한 개미군집시스템)

  • Lee, Sang-Heon;Kim, Yong-Dae
    • Journal of Korean Institute of Industrial Engineers
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    • v.35 no.2
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    • pp.160-170
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    • 2009
  • This paper studies a vehicle routing problem variant which considers customers to require simultaneous delivery and pick-up under time windows(VRPSDP-TW). The objective of this paper is to minimize the total travel distance of routes that satisfy both the delivery and pick-up demand. We propose a heuristic algorithm for solving the VRPSDP-TW, based on the ant colony system(ACS). In route construction, an insertion algorithm based ACS is applied and the interim solution is improved by local search. Through iterative processes, the heuristic algorithm drives the best solution. Experiments are implemented to evaluate a performance of the algorithm on some test instances from literature.

WEAK SUFFICIENT CONVERGENCE CONDITIONS AND APPLICATIONS FOR NEWTON METHODS

  • Argyros, Ioannis-K.
    • Journal of applied mathematics & informatics
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    • v.16 no.1_2
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    • pp.1-17
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    • 2004
  • The famous Newton-Kantorovich hypothesis has been used for a long time as a sufficient condition for the convergence of Newton method to a solution of an equation in connection with the Lipschitz continuity of the Frechet-derivative of the operator involved. Using Lipschitz and center-Lipschitz conditions we show that the Newton-Kantorovich hypothesis is weakened. The error bounds obtained under our semilocal convergence result are finer and the information on the location of the solution more precise than the corresponding ones given by the dominating Newton-Kantorovich theorem, and under the same hypotheses/computational cost, since the evaluation of the Lipschitz also requires the evaluation of the center-Lipschitz constant. In the case of local convergence we obtain a larger convergence radius than before. This observation is important in computational mathematics and can be used in connection to projection methods and in the construction of optimum mesh independence refinement strategies.

A Numerical Experiments on the Atmospheric Circulation over a Complex terrain around Coastal Area. Part I : A Verification of Proprietyh of Local Circulation Model Using the Linear Theory (연안부근 복잡지형의 대기유동장 수치실험 I -선형이론을 이용한 국지순환모형의 타당성 검토-)

  • 이화운;김유근;정우식
    • Journal of Environmental Science International
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    • v.8 no.5
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    • pp.555-558
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    • 1999
  • A sea/land breeze circulation system and a regional scale circulation system are formed at a region which has complex terrain around coastal area and affect to the dispersion and advection of air pollutants. Therefore, it is important that atmospheric circulation model should be well designed for the simulation of regional dispersion of air pollutants. For this, Local Circulation Model, LCM which has an ability of high resolution is used. To verify the propriety of a LCM, we compared the simulation result of LCM with an exact solution of a linear theory over a simple topography. Since they presented almost the same value and pattern of a vertical velocity at the level of 1 km, we had a reliance of a LCM. For the prediction of dispersion and advection of air pollutants, the wind filed should be calculated with high accuracy. A numerical simulation using LCM will provide more accurate results over a complex terrain around coastal area.

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Design and Evaluation of a Contention-Based High Throughput MAC with Delay Guarantee for Infrastructured IEEE 802.11WLANs

  • Kuo, Yaw-Wen;Tsai, Tung-Lin
    • Journal of Communications and Networks
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    • v.15 no.6
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    • pp.606-613
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    • 2013
  • This paper proposes a complete solution of a contention-based medium access control in wireless local networks to provide station level quality of service guarantees in both downstream and upstream directions. The solution, based on the mature distributed coordination function protocol, includes a new fixed contention window backoff scheme, a tuning procedure to derive the optimal parameters, a super mode to mitigate the downstream bottleneck at the access point, and a simple admission control algorithm. The proposed system guarantees that the probability of the delay bound violation is below a predefined threshold. In addition, high channel utilization can be achieved at the same time. The numerical results show that the system has advantages over the traditional binary exponential backoff scheme, including efficiency and easy configuration.

A study on the nonlinear analysis of spatial frame structures with nonlinear rotational spring elements (비선형 회전 스프링 요소를 갖는 공간 프레임의 구조의 비선형 해석에 관한 연구)

  • 이병채;박문식
    • Journal of the korean Society of Automotive Engineers
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    • v.12 no.2
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    • pp.29-42
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    • 1990
  • Three dimensional frame structures with such nonlinearities as large displacements, medium rotations, plastic hinges and local defects are efficiently analyzed by introducing the nonlinear rotational spring. Formulations are based on the incremental updated Lagrangian descriptions and the virtual work principle, Axial displacement and twisted angle in beam elements are interpolated linearly, while bending displacements are approximated by the Hermite polynomials. The modified are length method is used as a solution method. The moment-angle of rotation relationship obtained analytically or experimentally can be easily incorporated into the solution procedure. Several examples tested show that the present method can be used efficiently in analyzing nonlinear frame structures with plastic hinges or local defect.

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Optimal Design of Squeeze Film Damper Using an Enhanced Genetic Algorithm (향상된 유전알고리듬을 이용한 스퀴즈 필름 댐퍼의 최적설계)

  • 김영찬;안영공;양보석
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.11b
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    • pp.805-809
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    • 2001
  • This paper is presented to determine the optimal parameters of squeeze film damper using an enhanced genetic algorithm (EGA). The damper design parameters are the radius, length and radial clearance of the damper. The objective function is minimization of a transmitted load between bearing and foundation at the operating and critical speeds of a flexible rotor. The present algorithm was the synthesis of a genetic algorithm with simplex method for a local concentrate search. This hybrid algorithm is not only faster than the standard genetic algorithm, but also gives a more accurate solution and can find both the global and local optimum solution. The numerical example is presented that illustrated the effectiveness of enhanced genetic algorithm for the optimal design of the squeeze film damper for reducing transmitted load.

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Analysis of Problem Spaces and Algorithm Behaviors for Feature Selection (특징 선택을 위한 문제 공간과 알고리즘 동작 분석)

  • Lee Jin-Seon;Oh Il-Seok
    • Journal of KIISE:Software and Applications
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    • v.33 no.6
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    • pp.574-579
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    • 2006
  • The feature selection algorithms should broadly and efficiently explore the huge problem spaces to find a good solution. This paper attempts to gain insights on the fitness landscape of the spaces and to improve search capability of the algorithms. We investigate the solution spaces in terms of statistics on local maxima and minima. We also analyze behaviors of the existing algorithms and improve their solutions.

A Study on Local Segmental Motions of Methylene Chain in Poly(Butylene Terephthalate) in Solution Phase

  • NamGung, Hyeon;O, Jeong Rae;Lee, Jo Ung
    • Bulletin of the Korean Chemical Society
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    • v.21 no.11
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    • pp.1071-1076
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    • 2000
  • Temperature dependent data of 13C spin-lattice relaxation times and NOE factors for methylene carbons at 50.3MHz and 125.5 MHz have been used to probe the local chain dynamics of poly(butylene terephthalate) (PBT) in solution phase. The interpretation of the relaxation data for methylene chain carbons in PBT was attempted on the basis of several proposed motional models, among which the DLM model was found to be superior. Analysis based on the DLM model indicated that the motion of the $OCH_2groups$ was more restricted compared with the central methylene carbon, which is consistent with conclusions from solid state experiments reported by other investigators. Librational amplitudes of terminal and central carbon of PBT were estimated to be $29.84^{\circ}$ and $32.01^{\circ}respectively.