• Title/Summary/Keyword: Recursive estimation

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Real-Time Flood Forecasting Using Rainfall-Runoff Model(I) : Theory and Modeling (강우-유출모형을 이용한 실시간 홍수예측(I) : 이론과 모형화)

  • 정동국;이길성
    • Water for future
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    • v.27 no.1
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    • pp.89-99
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    • 1994
  • Flood forecasting in Korea has been based on the off-line parameter estimation method. But recent flood forecasting studies explore on-line recursive parameter estimation algorithms. In this study, a simultaneous adaptive estimation of system states and parameters for rainfall-runoff model is investigated for on-line real-time flood forecasting and parameter estimation. The proposed flood routing system is composed of Flood forecasting in Korea has been based on the off-line parameter estimation method. But recent flood forecasting studies explore on-line recursive parameter estimation algorithms. In this study, a simultaneous adaptive estimation of system states and parameters for rainfall-runoff model is investigated for on-line real-time flood forecasting and parameter estimation. The proposed flood routing system is composed of ø-index in the assessment of effective rainfall and the cascade of nonlinear reservoirs accounting for translation effect in flood routing. To combine the flood routing model with a parameter estimation model, system states and parameters are treated with the extended state-space formulation. Generalized least squares and maximum a posterior estimation algorithms are comparatively examined as estimation techniques for the state-space model. The sensitivity analysis is to investigate the identifiability of the parameters. The index of sensitivity used in this study is the covariance matrix of the estimated parameters.-index in the assessment of effective rainfall and the cascade of nonlinear reservoirs accounting for translation effect in flood routing. To combine the flood routing model with a parameter estimation model, system states and parameters are treated with the extended state-space formulation. Generalized least squares and maximum a posterior estimation algorithms are comparatively examined as estimation techniques for the state-space model. The sensitivity analysis is to investigate the identifiability of the parameters. The index of sensitivity used in this study is the covariance matrix of the estimated parameters.

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Fast CU Decision Algorithm using the Initial CU Size Estimation and PU modes' RD Cost (초기 CU 크기 예측과 PU 모드 예측 비용을 이용한 고속 CU 결정 알고리즘)

  • Yoo, Hyang-Mi;Shin, Soo-Yeon;Suh, Jae-Won
    • Journal of Broadcast Engineering
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    • v.19 no.3
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    • pp.405-414
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    • 2014
  • High Efficiency Video Coding(HEVC) obtains high compression ratio by applying recursive quad-tree structured coding unit(CU). However, this recursive quad-tree structure brings very high computational complexity to HEVC encoder. In this paper, we present fast CU decision algorithm in recursive quad-tree structure. The proposed algorithm estimates initial CU size before CTU encoding and checks the proposed condition using Coded Block Flag(CBF) and Rate-distortion cost to achieve the fast encoding time saving. And, intra mode estimation is also possible to be skipped using the CBF values acquired during the inter PU mode estimations. Experiment results shows that the proposed algorithm saved about 49.91% and 37.97% of encoding time according to the weighting condition.

Design of a Nuclear Reactor Controller Using a Model Predictive Control Method

  • Na, Man-Gyun;Jung, Dong-Won;Shin, Sun-Ho;Lee, Sun-Mi;Lee, Yoon-Joon;Jang, Jin-Wook;Lee, Ki-Bog
    • Journal of Mechanical Science and Technology
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    • v.18 no.12
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    • pp.2080-2094
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    • 2004
  • A model predictive controller is designed to control thermal power in a nuclear reactor. The basic concept of the model predictive control is to solve an optimization problem for finite future time steps at current time, to implement only the first optimal control input among the solved control inputs, and to repeat the procedure at each subsequent instant. A controller design model used for designing the model predictive controller is estimated every time step by applying a recursive parameter estimation algorithm. A 3-dimensional nuclear reactor analysis code, MASTER that was developed by Korea Atomic Energy Research Institute (KAERI), was used to verify the proposed controller for a nuclear reactor. It was known that the nuclear power controlled by the proposed controller well tracks the desired power level and the desired axial power distribution.

Modeling and Characteristic Analysis of HEV Li-ion Battery Using Recursive Least Square Estimation (최소 자승법을 이용한 하이브리드용 리튬이온 배터리 모델링 및 특성분석)

  • Kim, Ho-Gi;Heo, Sang-Jin;Kang, Gu-Bae
    • Transactions of the Korean Society of Automotive Engineers
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    • v.17 no.1
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    • pp.130-136
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    • 2009
  • A lumped parameter model of Li-ion battery in hybrid electric vehicle(HEV) is constructed and system parameters are identified by using recursive least square estimation for different C-rates, SOCs and temperatures. The system characteristics of pole and zero in frequency domain are analyzed with the parameters obtained from different conditions. The parameterized model of Li-ion battery indicates highly dependant of temperatures. The system pole and internal resistance changes 6.6 and 18 times at $-20^{\circ}C$, comparing with those at $25^{\circ}C$, respectively. These results will be utilized on constructing model-based state observer or an on-line identification and an adaptation of the model parameters in battery management systems for hybrid electric vehicle applications.

A Square-Root Forward Backward Correlation-based Projection Approximation for Subspace Tracking (신호부공간 추정 성능 향상을 위한 전후방 상관과 제곱근행렬 갱신을 이용한 COPAST(correlation-based projection approximation for subspace-tracking) 알고리즘 연구)

  • Lim, June-Seok;Pyeon, Yong-Kug
    • 전자공학회논문지 IE
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    • v.48 no.1
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    • pp.7-15
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    • 2011
  • In this paper, we propose a correlation-based subspace estimation technique, which is called square-root forward/backward correlation-based projection approximation subspace tracking(SRFB-COPAST). The SRFB-COPAST utilizes the forward and backward correlation matrix as well as square-root recursive matrix update in projection approximation approach to develop the subspace tracking algorithm. With the projection approximation, the square-root recursive FB-COPAST is presented. The proposed algorithm has the better performance than the recently developed COPAST method.

Efficient Calculation for Decision Feedback Algorithms Based on Zero-Error Probability Criterion (영확률 성능기준에 근거한 결정궤환 알고리듬의 효율적인 계산)

  • Kim, Namyong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.2
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    • pp.247-252
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    • 2015
  • Adaptive algorithms based on the criterion of zero-error probability (ZEP) have robustness to impulsive noise and their decision feedback (DF) versions are known to compensate effectively for severe multipath channel distortions. However the ZEP-DF algorithm computes several summation operations at each iteration time for each filter section and this plays an obstacle role in practical implementation. In this paper, the ZEP-DF with recursive gradient estimation (RGE) method is proposed and shown to reduce the computational burden of O(N) to a constant which is independent of the sample size N. Also the weight update of the initial state and the steady state is a continuous process without bringing about any propagation of gradient estimation error in DF structure.

A Connection Admission Control with Recursive Formula in ATM Networks (ATM 망에서 재귀 연산에 의한 연결 수락 제어)

  • Nam, Jae-Hyun;Park, Chan-Jung;Lee, Kee-Hyun
    • The Transactions of the Korea Information Processing Society
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    • v.4 no.7
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    • pp.1788-1796
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    • 1997
  • In this paper, we propose a new connection admission control(CAC) algorithm for traffic control in ATM network in which traffic estimation is performed based on user-specified parameters at every moment of connection request or connection release by recursive formula which makes real-time calculation possible. And traffic estimation using cell flow measurement is carried out when the number of connectioned calls does not change during a measurement reflection period. Performance analysis of the proposed method is carried out using several aspects for homogeneous and heterogeneous bursty traffic. The results showed that the proposed CAC method revealed better performance, than conventional CAC method for burst model in both utilization and QoS point of view.

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Geometric Correction for Uneven Quadric Projection Surfaces Using Recursive Subdivision of B$\acute{e}$zier Patches

  • Ahmed, Atif;Hafiz, Rehan;Khan, Muhammad Murtaza;Cho, Yongju;Cha, Jihun
    • ETRI Journal
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    • v.35 no.6
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    • pp.1115-1125
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    • 2013
  • This paper presents a scheme for geometric correction of projected content for planar and quadratic projection surfaces. The scheme does not require the projection surface to be perfectly quadratic or planar and is therefore suitable for uneven low-cost commercial and home projection surfaces. An approach based on the recursive subdivision of second-order B$\acute{e}$zier patches is proposed for the estimation of projection distortion owing to surface imperfections. Unlike existing schemes, the proposed scheme is completely automatic, requires no prior knowledge of the projection surface, and uses a single uncalibrated camera without requiring any physical markers on the projection surface. Furthermore, the scheme is scalable for geometric calibration of multi-projector setups. The efficacy of the proposed scheme is demonstrated using simulations and via practical experiments on various surfaces. A relative distortion error metric is also introduced that provides a quantitative measure of the suppression of geometric distortions, which occurs as the result of an imperfect projection surface.

A Simple Enhancement of Coherent Detection for Initial Frame Synchronization in W-CDMA Systems (W-CDMA 시스템의 초기 프레임 동기 획득을 위한 Coherent 검출 방식의 성능 개선)

  • Choi, Won-Eung;Joo, Jung-Suk
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.47 no.10
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    • pp.43-48
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    • 2010
  • In general, in order to reduce an initial cell searching time, W-CDMA systems adopt a three-step cell search scheme: slot synchronization, frame synchronization, and primary scrambling code identification. We consider the second step (frame synchronization), in which a coherent detection using P-SCH (primary synchronization channel) is possible. In this paper, we propose a new coherent detection scheme, where a first order recursive filter is used to enhance channel estimation performance. Computer simulation results indicate that the detection performance of the proposed scheme can be robust over large range of frequency offset.