• Title/Summary/Keyword: Adaptive Search

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Design of Optimal Fuzzy Logic based PI Controller using Multiple Tabu Search Algorithm for Load Frequency Control

  • Pothiya Saravuth;Ngamroo Issarachai;Runggeratigul Suwan;Tantaswadi Prinya
    • International Journal of Control, Automation, and Systems
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    • v.4 no.2
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    • pp.155-164
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    • 2006
  • This paper focuses on a new optimization technique of a fuzzy logic based proportional integral (FLPI) load frequency controller by the multiple tabu search (MTS) algorithm. Conventionally, the membership functions and control rules of fuzzy logic control are obtained by trial and error method or experiences of designers. To overcome this problem, the MTS algorithm is proposed to simultaneously tune proportional integral gains, the membership functions and control rules of a FLPI load frequency controller in order to minimize the frequency deviations of the interconnected power system against load disturbances. The MTS algorithm introduces additional techniques for improvement of the search process such as initialization, adaptive search, multiple searches, crossover and restart process. Simulation results explicitly show that the performance of the proposed FLPI controller is superior to conventional PI and FLPI controllers in terms of overshoot and settling time. Furthermore, the robustness of the proposed FLPI controller under variation of system parameters and load change are higher than that of conventional PI and FLPI controllers.

Motion Search Region Prediction using Neural Network Vector Quantization (신경 회로망 벡터 양자화를 이용한 움직임 탐색 영역의 예측)

  • Ryu, Dae-Hyun;Kim, Jae-Chang
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.1
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    • pp.161-169
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    • 1996
  • This paper presents a new search region prediction method using vector quantization for the motion estimation. We find motion vectors using the full search BMA from two successive frame images first. Then the motion vectors are used for training a codebook. The trained codebook is the predicted search region. We used the unsupervised neural network for VQ encoding and codebook design. A major advantage of formulating VQ as neural networks is that the large number of adaptive training algorithm that are used for neural networks can be applied to VQ. The proposed method reduces the computation and reduce the bits required to represent the motion vectors because of the smaller search points. The computer simulation results show the increased PSNR as compared with the other block matching algorithms.

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Fast Disparity Motion Vector Searching Method for the MV-HEVC (MV-HEVC에서 빠른 변위 움직임 벡터 탐색 방법)

  • Lee, Jae-Yung;Han, Jong-Ki
    • Journal of Broadcast Engineering
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    • v.22 no.2
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    • pp.240-252
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    • 2017
  • Multi-view video codec based on the High Efficiency Video Coding (MV-HEVC) has high encoding complexity because it exploits an additional reference picture for disparity compensation prediction (DCP) when the picture of dependent view is encoded. In this paper, we propose an efficient method to reduce the complexity of disparity motion vector search for the MV-HEVC. The proposed method includes the initial search point decision method using affine transform and the adaptive search range decision method. The simulation results show that the proposed method reduces the complexity of disparity motion vector search up to 90.78% with negligible coding efficiency degradation. Also the results show that the proposed method outperforms other conventional techniques reducing complexity.

A Selective Motion Estimation Algorithm with Variable Block Sizes (다양한 블록 크기 기반 선택적 움직임 추정 알고리즘)

  • 최웅일;전병우
    • Journal of Broadcast Engineering
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    • v.7 no.4
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    • pp.317-326
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    • 2002
  • The adaptive coding schemes in H.264 standardization provide a significant ceding efficiency and some additional features like error resilience and network friendliness. The variable block size motion compensation using multiple reference frames is one of the key H.264 coding elements to provide main performance gain, but also the main culprit that increases the overall computational complexity. For this reason, this paper proposes a selective motion estimation algorithm based on variable block size for fast motion estimation in H.264. After we find the SAD(Sum of Absolute Difference) at initial points using diamond search, we decide whether to perform additional motion search in each block. Simulation results show that the proposed method is five times faster than the conventional full search in case of search range $\pm$32.

Complexity-Reduction Algorithm of Speech Coder (QCELP) for CDMA Digital Cellular System (CDMA 디지틀 셀룰라용 음성 부호화기 (QCELP) 의 복잡도 감소 알고리즘)

  • 이인성
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.3
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    • pp.126-132
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    • 1996
  • In this paper, the complexity reduction method for QCELP speech coder (IS-96) without any perfomrance degradation is proposed for the vecoder of CDMA digital cellular system. The energy terms in pitch parameter search and codebook search routines that require large computations are calculated recursively by utilizing the overlapped structure of code vectors in adaptive codebook and excitation codebook. The additional complexity reduction in the codebook search routine can be achieved by using a simple form in calculation of the energy term when the initial codebook value is zero. In the case of lower transmission rates such as 4,2,1 kbps, the complexity reduction by recursive calulations of energy term is increased.

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Hybrid evolutionary identification of output-error state-space models

  • Dertimanis, Vasilis K.;Chatzi, Eleni N.;Spiridonakos, Minas D.
    • Structural Monitoring and Maintenance
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    • v.1 no.4
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    • pp.427-449
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    • 2014
  • A hybrid optimization method for the identification of state-space models is presented in this study. Hybridization is succeeded by combining the advantages of deterministic and stochastic algorithms in a superior scheme that promises faster convergence rate and reliability in the search for the global optimum. The proposed hybrid algorithm is developed by replacing the original stochastic mutation operator of Evolution Strategies (ES) by the Levenberg-Marquardt (LM) quasi-Newton algorithm. This substitution results in a scheme where the entire population cloud is involved in the search for the global optimum, while single individuals are involved in the local search, undertaken by the LM method. The novel hybrid identification framework is assessed through the Monte Carlo analysis of a simulated system and an experimental case study on a shear frame structure. Comparisons to subspace identification, as well as to conventional, self-adaptive ES provide significant indication of superior performance.

Model-Based Tabu Search Algorithm for Free-Space Optical Communication with a Novel Parallel Wavefront Correction System

  • Li, Zhaokun;Zhao, Xiaohui;Cao, Jingtai;Liu, Wei
    • Journal of the Optical Society of Korea
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    • v.19 no.1
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    • pp.45-54
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    • 2015
  • In this study, a novel parallel wavefront correction system architecture is proposed, and a model-based tabu search (MBTS) algorithm is introduced for this new system to compensate wavefront aberration caused by atmospheric turbulence in a free-space optical (FSO) communication system. The algorithm flowchart is presented, and a simple hypothetical design for the parallel correction system with multiple adaptive optical (AO) subsystems is given. The simulated performance of MBTS for an AO-FSO system is analyzed. The results indicate that the proposed algorithm offers better performance in wavefront aberration compensation, coupling efficiency, and convergence speed than a stochastic parallel gradient descent (SPGD) algorithm.

A Search Range Decision Algorithm For Motion Vector Estimation (움직임 벡터 추정을 위한 탐색 영역 결정 방식)

  • 이민구;홍민철
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.2C
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    • pp.141-146
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    • 2003
  • In this paper, we propose an adaptive search range decision algorithm for motion vector estimation in video coding. The performance of general motion estimation method in video coding mechanism is evaluated with respect to the motion vector accuracy and the complexity, which is trade-off. The proposed algorithm that plays as a role of pre-processing for motion vector estimation determines the motion search range by the local statistics of motion vector of neighboring blocks, resulting in more than 60(%) reduction of the computational cost without the loss of visual quality. Experimental results show the capability of the proposed algorithm.