• 제목/요약/키워드: gradient algorithm

검색결과 1,165건 처리시간 0.034초

AN AFFINE SCALING INTERIOR ALGORITHM VIA CONJUGATE GRADIENT AND LANCZOS METHODS FOR BOUND-CONSTRAINED NONLINEAR OPTIMIZATION

  • Jia, Chunxia;Zhu, Detong
    • Journal of applied mathematics & informatics
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    • 제29권1_2호
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    • pp.173-190
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    • 2011
  • In this paper, we construct a new approach of affine scaling interior algorithm using the affine scaling conjugate gradient and Lanczos methods for bound constrained nonlinear optimization. We get the iterative direction by solving quadratic model via affine scaling conjugate gradient and Lanczos methods. By using the line search backtracking technique, we will find an acceptable trial step length along this direction which makes the iterate point strictly feasible and the objective function nonmonotonically decreasing. Global convergence and local superlinear convergence rate of the proposed algorithm are established under some reasonable conditions. Finally, we present some numerical results to illustrate the effectiveness of the proposed algorithm.

Nonlinear optimization algorithm using monotonically increasing quantization resolution

  • Jinwuk Seok;Jeong-Si Kim
    • ETRI Journal
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    • 제45권1호
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    • pp.119-130
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    • 2023
  • We propose a quantized gradient search algorithm that can achieve global optimization by monotonically reducing the quantization step with respect to time when quantization is composed of integer or fixed-point fractional values applied to an optimization algorithm. According to the white noise hypothesis states, a quantization step is sufficiently small and the quantization is well defined, the round-off error caused by quantization can be regarded as a random variable with identically independent distribution. Thus, we rewrite the searching equation based on a gradient descent as a stochastic differential equation and obtain the monotonically decreasing rate of the quantization step, enabling the global optimization by stochastic analysis for deriving an objective function. Consequently, when the search equation is quantized by a monotonically decreasing quantization step, which suitably reduces the round-off error, we can derive the searching algorithm evolving from an optimization algorithm. Numerical simulations indicate that due to the property of quantization-based global optimization, the proposed algorithm shows better optimization performance on a search space to each iteration than the conventional algorithm with a higher success rate and fewer iterations.

유전 알고리즘을 적용한 선박용 위성 안테나의 안정화 알고리즘의 설계 (The Design of the Stabilized Algorithm for Shipboard Satellite Antenna Systems using Genetic Algorithm)

  • 고운용;황승욱;진강규
    • 한국항해학회지
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    • 제25권4호
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    • pp.361-369
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    • 2001
  • This thesis describes the design of a stabilized algorithm for shipboard satellite antenna systems which can enhance the tracking performance. In order to overcome some drawbacks of the conventional step tracking algorithm, the proposed algorithm searches for the best tracking angles using gradient-based formulae and signal intensities measured according to a search pattern. The effectiveness of the proposed algorithm is demonstrated through simulation using real-world data.

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선박용 위성 안테나용 트랙킹 알고리즘 (A Tracking Algorithm for Shipboard Satellite Antenna Systems)

  • 고운용;황승욱;진강규
    • Journal of Advanced Marine Engineering and Technology
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    • 제25권5호
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    • pp.1115-1121
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    • 2001
  • This paper presents the development of a tracking algorithm for shipborad satellite antenna systems which can enhance the tracking performance. In order to overcome some drawbacks of the conventional step tracking algorithm a new tracking algorithm is proposed. The proposed algorithm searches for the best tracking angles using gradient-based formulae and signal intensities measured according to a search pattern. The effectiveness of the proposed algorithm is demonstrated through simulation using real data.

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선박용 위성 안테나의 트랙킹 알고리즘 개발 (Development of a Tracking Algorithm for Shipboard Satellite Antenna Systems)

  • 고운용;황승욱;진강규
    • 한국마린엔지니어링학회:학술대회논문집
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    • 한국마린엔지니어링학회 2001년도 춘계학술대회 논문집
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    • pp.219-224
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    • 2001
  • This paper presents the development of a tracking algorithm for shipboard satellite antenna systems which can enhance the tracking performance. In order to overcome some drawbacks of the conventional step tracking algorithm, the proposed algorithm searches for the best tracking angles using gradient-based formulae and signal intensities measured according to a search pattern. The effectiveness of the proposed algorithm is demonstrated through simulation using real-world data.

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Improved Gradient Direction Assisted Linking Algorithm for Linear Feature Extraction in High Resolution Satellite Images, an Iterative Dynamic Programming Approach

  • Yang, Kai;Liew, Soo Chin;Lee, Ken Yoong;Kwoh, Leong Keong
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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    • pp.408-410
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    • 2003
  • In this paper, an improved gradient direction assisted linking algorithm is proposed. This algorithm begins with initial seeds satisfying some local criteria. Then it will search along the direction provided by the initial point. A window will be generated in the gradient direction of the current point. Instead of the conventional method which only considers the value of the local salient structure, an improved mathematical model is proposed to describe the desired linear features. This model not only considers the value of the salient structure but also the direction of it. Furthermore, the linking problem under this model can be efficiently solved by dynamic programming method. This algorithm is tested for linear features detection in IKONOS images. The result demonstrates this algorithm is quite promising.

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전영역 탐색의 고속 움직임 예측에서 기울기 크기와 부 블록을 이용한 적응 매칭 스캔 알고리즘 (Adaptive Matching Scan Algorithm Based on Gradient Magnitude and Sub-blocks in Fast Motion Estimation of Full Search)

  • 김종남;최태선
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 1999년도 추계종합학술대회 논문집
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    • pp.1097-1100
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    • 1999
  • Due to the significant computation of full search in motion estimation, extensive research in fast motion estimation algorithms has been carried out. However, most of the algorithms have the degradation in predicted images compared with the full search algorithm. To reduce an amount of significant computation while keeping the same prediction quality of the full search, we propose a fast block-matching algorithm based on gradient magnitude of reference block without any degradation of predicted image. By using Taylor series expansion, we show that the block matching errors between reference block and candidate block are proportional to the gradient magnitude of matching block. With the derived result, we propose fast full search algorithm with adaptively determined scan direction in the block matching. Experimentally, our proposed algorithm is very efficient in terms of computational speedup and has the smallest computation among all the conventional full search algorithms. Therefore, our algorithm is useful in VLSI implementation of video encoder requiring real-time application.

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WISE 펄스 도플러 윈드라이다 품질관리 알고리즘 개발 (Development of a Quality Check Algorithm for the WISE Pulsed Doppler Wind Lidar)

  • 박문수;최민혁
    • 대기
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    • 제26권3호
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    • pp.461-471
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    • 2016
  • A quality check algorithm for the Weather Information Service Engine pulsed Doppler wind lidar is developed from a view point of spatial and temporal consistencies of observed wind speed. Threshold values for quality check are determined by statistical analysis on the standard deviation of 3-component of wind speed obtained by a wind lidar, and the vertical gradient of horizontal wind speed obtained by a radiosonde system. The algorithm includes carrier-to-noise ratio (CNR) check, data availability check, and vertical gradient of horizontal wind speed check. That is, data sets whose CNR is less than -29 dB, data availability is less than 90%, or vertical gradient of horizontal wind speed is less than $-0.028s^{-1}$ or larger than $0.032s^{-1}$ are classified as 'doubtful', and flagged. The developed quality check algorithm is applied to data obtained at Bucheon station for the period from 1 to 30 September 2015. It is found that the number of 'doubtful' data shows maxima around 2000 m high, but the ratio of 'doubtful' to height-total data increases with increasing height due to atmospheric boundary height, cloud, or rainfall, etc. It is also found that the quality check by data availability is more effective than those by carrier to noise ratio or vertical gradient of horizontal wind speed to remove an erroneous noise data.

자력 변화율 텐서를 이용한 자기 쌍극자 위치 결정 (Detection of a Magnetic Dipole by Means of Magnetic Gradient Tensor)

  • 임형래
    • 한국지구과학회지
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    • 제32권6호
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    • pp.595-601
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    • 2011
  • 이 논문에서는 자력 변화율 텐서를 이용하여 자기 쌍극자의 위치 정보를 파악하는 알고리즘에 대하여 기술하였다. 수직으로 자화된 자기 쌍극자에 의한 자력 변화율 텐서에서 출발하여 자기 쌍극자의 위치 벡터를 유도하였다. 그러나 이 경우 자기 쌍극자의 모멘트에 대한 정보가 주어지지 않았으므로 자기 쌍극자의 위치 벡터가 불완전하게 유도된다. 이를 극복하기 위하여 여러 측정점에서 측정된 자력 변화율 텐서값이 있다고 가정하고 이를 이용하여 자동으로 자기 쌍극자의 위치를 찾아내는 알고리즘을 제안하였다. 시추공에서 자력 변화율 텐서가 측정되었다고 가정한 합성 모델 실험에서 자력 변화율 텐서와 자기 쌍극자 자동 탐지 알고리즘을 이용하여 자기 쌍극자의 위치를 정확하게 찾을 수 있음을 확인하였다.

FCM 클러스터링 알고리즘에 기초한 퍼지 모델링 (Fuzzy Modeling based on FCM Clustering Algorithm)

  • 윤기찬;오성권
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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    • pp.373-373
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    • 2000
  • In this paper, we propose a fuzzy modeling algorithm which divides the input space more efficiently than convention methods by taking into consideration correlations between components of sample data. The proposed fuzzy modeling algorithm consists of two steps: coarse tuning, which determines consequent parameters approximately using FCRM clustering method, and fine tuning, which adjusts the premise and consequent parameters more precisely by gradient descent algorithm. To evaluate the performance of the proposed fuzzy mode, we use the numerical data of nonlinear function.

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