• Title/Summary/Keyword: recursive system

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Probabilistic damage detection of structures with uncertainties under unknown excitations based on Parametric Kalman filter with unknown Input

  • Liu, Lijun;Su, Han;Lei, Ying
    • Structural Engineering and Mechanics
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    • v.63 no.6
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    • pp.779-788
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    • 2017
  • System identification and damage detection for structural health monitoring have received considerable attention. Various time domain analysis methodologies based on measured vibration data of structures have been proposed. Among them, recursive least-squares estimation of structural parameters which is also known as parametric Kalman filter (PKF) approach has been studied. However, the conventional PKF requires that all the external excitations (inputs) be available. On the other hand, structural uncertainties are inevitable for civil infrastructures, it is necessary to develop approaches for probabilistic damage detection of structures. In this paper, a parametric Kalman filter with unknown inputs (PKF-UI) is proposed for the simultaneous identification of structural parameters and the unmeasured external inputs. Analytical recursive formulations of the proposed PKF-UI are derived based on the conventional PKF. Two scenarios of linear observation equations and nonlinear observation equations are discussed, respectively. Such a straightforward derivation of PKF-UI is not available in the literature. Then, the proposed PKF-UI is utilized for probabilistic damage detection of structures by considering the uncertainties of structural parameters. Structural damage index and the damage probability are derived from the statistical values of the identified structural parameters of intact and damaged structure. Some numerical examples are used to validate the proposed method.

Self-Organizing Fuzzy Modeling Using Creation of Clusters (클러스터 생성을 이용한 자기구성 퍼지 모델링)

  • Koh, Taek-Beom
    • Journal of the Korean Institute of Intelligent Systems
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    • v.12 no.4
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    • pp.334-340
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    • 2002
  • This paper proposes a self-organizing fuzzy modeling which can create a new hyperplane-shaped cluster by applying multiple regression to input/output data with relatively large fuzzy entropy, add the new cluster to fuzzy rule base and adjust parameters of the fuzzy model in repetition. Tn the coarse tuning, weighted recursive least squared algorithm and fuzzy C-regression model clustering are used and in the fine tuning, gradient descent algorithm is used to adjust parameters of the fuzzy model precisely And learning rates are optimized by utilizing meiosis-genetic algorithm. To check the effectiveness and feasibility of the suggested algorithm, four representative examples for system identification are examined and the performance of the identified fuzzy model is demonstrated in comparison with that of the conventional fuzzy models.

IPv6 / IPv6 DNS Set Up and Work Analysis From Multiple Operating System (다양한 OS환경(사용자 PC)에서의 IPv6 / IPv6 DNS 설정 및 동작 분석)

  • Kim, Jin-Seok;Seo, Yu-Hwa;Lee, Ki-Young;Shin, Yong-Tae
    • Proceedings of the Korean Information Science Society Conference
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    • 2007.06d
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    • pp.327-332
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    • 2007
  • 현재 전 세계는 IPv4 주소 자원의 고갈에 대비한 IPv6의 도입을 위해 국가 차원의 전략적인 노력을 기울이고 있으며, 이에 따라 IPv4망에서 IPv6망으로의 안정적인 전이를 위한 상호 운영기술이 지속적으로 개발되고 있다. 이러한 기술을 적용하기 위한 다양한 응용 프로그램의 운영을 위해서 IPv6 뿐만 아니라 IPv6 기반의 Recursive DNS 기술도 그 핵심적인 요소라 할 수 있다. 그렇지만 IPv6 및 IPv6 DNS를 구축과 동시에 사용자 PC의 OS에도 IPv6 및 IPv6 DNS가 설정되어야 한다. 그러나 사용자가 사용하는 운영체제의 종류가 다양하기 때문에 운영체제별 동작도 다르다. 따라서 IPv6 및 IPv6 Recursive DNS을 사용하기 위해서는 사용자 PC의 서로 상이한 운영체제별 IPv6 및 IPv6 DNS 동작을 파악해야만 한다. 이에 본 논문은 운영체제별 IPv6 및 IPv6 DNS 동작을 확인하고 IPv6 및 IPv6 DNS 구축시 고려해야 할 가이드라인을 제시한다.

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Low Complexity MMSE with Successive Interference Cancellation for OFDM Systems over Time-selective Channels (시변 채널 환경에서 OFDM 시스템을 위한 복잡도가 감소된 MMSE-SIC 등화기법)

  • Park, Ji-Hyun;Hwang, Seung-Hoon;Whang, Keum-Chan
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.7A
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    • pp.743-750
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    • 2008
  • Orthogonal frequency division multiplexing (OFDM) is a attractive modulation scheme for high data rate transmission in frequency-selective channels. However, the time selectivity of wireless channel introduces intercarrier interference (ICI), and consequently degrades system performance. In this paper, we first propose a novel recursive algorithm for minimum mean squared error (MMSE) with successive interference cancellation (SIC). The proposed algorithm can significantly reduce the complexity of the MMSE-SIC scheme and achieve the same performance when optimal ordering is known. Also, the further reduced scheme of the proposed algorithm can be developed based on ICI properties, while preserving performance.

Recursive compensation algorithm application to the optimal edge selection

  • Chung, C.H.;Lee, K.S.
    • 제어로봇시스템학회:학술대회논문집
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    • 1992.10b
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    • pp.79-84
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    • 1992
  • Path planning is an important task for optimal motion of a robot in structured or unstructured environment. The goal of this paper is to plan the optimal collision-free path in 3D, when a robot is navigated to pick up some tools or to repair some parts from various locations. To accomplish the goal, the Path Coordinator is proposed to have the capabilities of an obstacle avoidance strategy and a traveling salesman problem strategy (TSP). The obstacle avoidance strategy is to plan the shortest collision-free path between each pair of n locations in 2D or in 3D. The TSP strategy is to compute a minimal system cost of a tour that is defined as a closed path navigating each location exactly once. The TSP strategy can be implemented by the Hopfield Network. The obstacle avoidance strategy in 2D can be implemented by the VGraph Algorithm. However, the VGraph Algorithm is not useful in 3D, because it can't compute the global optimality in 3D. Thus, the Path Coordinator is used to solve this problem, having the capabilities of selecting the optimal edges by the modified Genetic Algorithm and computing the optimal nodes along the optimal edges by the Recursive Compensation Algorithm.

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Active Control of Noise in Ducts Using Stabilized Multi-Channel Recursive LMS Algorithms (안정화된 다중채널 RLMS 알고리즘을 이용한 덕트의 능동소음제어)

  • Nam, Hyun-Do;Nam, Seung-Uk;Seo, Sung-Dae;Ahn, Dong-Jun
    • Proceedings of the KIEE Conference
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    • 2006.04a
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    • pp.30-32
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    • 2006
  • An adaptive IIR filter in ANC(Active Noise Control) systems is more effective than an adaptive FIR filter when acoustic feedback exists, in which cause an order of an adaptive FIR filter must be very large if some of poles of the ideal control filter are near the unit circle. But the IIR filters may have stability problems especially when the adaptive algorithm for adaptive filters is not yet converged. In this paper, a stabilized multi-channel recursive LMS (MCRLMS) algorithm for an adaptive multi-channel IIR filter is presented. RLMS algorithms usually diverge before the algorithm is not yet converged. So, in the beginning of the ANC system, the stability of the RLMS algorithms could be Improved by pulling the poles of the IIR filter to the center of the unit circle, and returning the poles to their original positions after the filter converges. Computer simulations and experiments for dipole ducts using a TMS320C32 digital signal processor have performed to show the effectiveness of a proposed algorithm.

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Seismic response of a highway bridge in case of vehicle-bridge dynamic interaction

  • Erdogan, Yildirim S.;Catbas, Necati F.
    • Earthquakes and Structures
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    • v.18 no.1
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    • pp.1-14
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    • 2020
  • The vehicle-bridge interaction (VBI) analysis might be cumbersome and computationally expensive in bridge engineering due to the necessity of solving large number of coupled system of equations. However, VBI analysis can provide valuable insights into the dynamic behavior of highway bridges under specific loading conditions. Hence, this paper presents a numerical study on the dynamic behavior of a conventional highway bridge under strong near-field and far-field earthquake motions considering the VBI effects. A recursive substructuring method, which enables solving bridge and vehicle equations of motion separately and suitable to be adapted to general purpose finite element softwares, was used. A thorough analysis that provides valuable information about the effect of various traffic conditions, vehicle velocity, road roughness and effect of soil conditions under far-field and near-field strong earthquake motions has been presented. A real-life concrete highway bridge was chosen for numerical demonstrations. In addition, sprung mass models of vehicles consist of conventional truck and car models were created using physical and dynamic properties adopted from literature. Various scenarios, of which the results may help to highlight the different aspects of the dynamic response of concrete highway bridges under strong earthquakes, have been considered.

A Study on the Modeling and Diagnostics on Chatter in Endmilling Operation (엔드밀 가공시 채터 모델링과 진단에 관한 연구)

  • Kim, Young-Kook;Yoon, Moon-Chul;Ha, Man-Kyeong;Sim, Seong-Bo
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.10
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    • pp.101-108
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    • 2001
  • In this study, the static and dynamic characteristics of endmilling process were modelled and the analytic realization of chatter mechanism was discussed. In this reward, We have discussed on the comparative assessment of recursive time series modeling algorithms that cal represent time machining process and detect the abnormal machining behaviors in precision endmilling operation. In this study, simulation and experimental works were performed to show the malfunctional behaviors. For this purpose, new recursive algorithm(RLSM) was adopted for the oil-line system identification and monitoring of a machining process, we can apply these new algorithms in real process for detection of abnormal chatter. Also, The stability lobe of chatter was analysed by varying parameter of cutting dynamics in regenerative chatter mechanics.

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Time domain earthquake response analysis method for 2-D soil-structure interaction systems

  • Kim, Doo-Kie;Yun, Chung-Bang
    • Structural Engineering and Mechanics
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    • v.15 no.6
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    • pp.717-733
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    • 2003
  • A time domain method is presented for soil-structure interaction analysis under seismic excitations. It is based on the finite element formulation incorporating infinite elements for the far field soil region. Equivalent earthquake input forces are calculated based on the free field responses along the interface between the near and far field soil regions utilizing the fixed exterior boundary method in the frequency domain. Then, the input forces are transformed into the time domain by using inverse Fourier transform. The dynamic stiffness matrices of the far field soil region formulated using the analytical frequency-dependent infinite elements in the frequency domain can be easily transformed into the corresponding matrices in the time domain. Hence, the response can be analytically computed in the time domain. A recursive procedure is proposed to compute the interaction forces along the interface and the responses of the soil-structure system in the time domain. Earthquake response analyses have been carried out on a multi-layered half-space and a tunnel embedded in a layered half-space with the assumption of the linearity of the near and far field soil region, and results are compared with those obtained by the conventional method in the frequency domain.

Implementation of Recursive DSP Algorithms Based on an Optimal Multiprocessor Scheduler (최적 멀티프로세서 스케줄러를 이용한 재귀 DSP 알고리듬의 구현)

  • Kim Hyeong-Kyo
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.10 no.2
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    • pp.228-234
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    • 2006
  • This paper describes a systematic process which can generate a complete circuit specification efficiently for a given recursive DSP algorithm based on an optimal multiprocessor scheduler. The process is composed of two states: scheduling and circuit synthesis. The scheduling part accepts a fully specified flow graph(FSFG) as an input, and generates an optimal synchronous multiprocessor schedule. Then the circuit synthesis part translates the modified schedule into a complete circuit diagram including a control specification. The circuit diagram can be applied to a silicon compiler for VLSI layout generation. This paper illustrates the whole process with an example of a second order Gray-Market lattice filter.