• Title/Summary/Keyword: nonlinear processing

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Identification of nonlinear elastic structures using empirical mode decomposition and nonlinear normal modes

  • Poon, C.W.;Chang, C.C.
    • Smart Structures and Systems
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    • v.3 no.4
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    • pp.423-437
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    • 2007
  • The empirical mode decomposition (EMD) method is well-known for its ability to decompose a multi-component signal into a set of intrinsic mode functions (IMFs). The method uses a sifting process in which local extrema of a signal are identified and followed by a spline fitting approximation for decomposition. This method provides an effective and robust approach for decomposing nonlinear and non-stationary signals. On the other hand, the IMF components do not automatically guarantee a well-defined physical meaning hence it is necessary to validate the IMF components carefully prior to any further processing and interpretation. In this paper, an attempt to use the EMD method to identify properties of nonlinear elastic multi-degree-of-freedom structures is explored. It is first shown that the IMF components of the displacement and velocity responses of a nonlinear elastic structure are numerically close to the nonlinear normal mode (NNM) responses obtained from two-dimensional invariant manifolds. The IMF components can then be used in the context of the NNM method to estimate the properties of the nonlinear elastic structure. A two-degree-of-freedom shear-beam building model is used as an example to illustrate the proposed technique. Numerical results show that combining the EMD and the NNM method provides a possible means for obtaining nonlinear properties in a structure.

A design of synchronous nonlinear and parallel for pipeline stage on IP-based H.264 decoder implementation (IP기반 H.264 디코더 설계를 위한 동기식 비선형 및 병렬화 파이프라인 설계)

  • Ko, Byung-Soo;Kong, Jin-Hyeung
    • Proceedings of the IEEK Conference
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    • 2008.06a
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    • pp.409-410
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    • 2008
  • This paper presents nonlinear and parallel design for synchronous pipelining in IP-based H.264 decoder implementation. Since H.264 decoder includes the dataflow of feedback loop, the data dependency requires one NOP stage per pipelining latency to drop the throughput into 1/2. Further, it is found that, in execution time, the stage scheduled for MC is more occupied than that for CAVLD/ITQ/DF. The less efficient stage would be improved by nonlinear scheduling, while the fully-utilized stage could be accelerated by parallel scheduling of IP. The optimization yields 3 nonlinear {CAVLD&ITQ}|3 parallel (MC/IP&Rec.)| 3 nonlinear {DF} pipelined architecture for IP-based H.264 decoder. In experiments, the nonlinear and parallel pipelined H.264 decoder, including existing IPs, could deal with full HD video at 41.86MHz, in real time processing.

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The design of web tension control system using nonlinear feedback (비선형 장력 제어 시스템 설계)

  • Oh, Seung-Rohk;Oh, Dong-Chul
    • Proceedings of the KIEE Conference
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    • 2005.10b
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    • pp.164-166
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    • 2005
  • We consider a web transport system. The objective of this paper is to design the controller such that desired tension and processing on web transport system. We propose the new design method which is independent with operating condition. The proposed method used a nonlinear feedback to transform to linear system. We show a performance of controller via the simulation.

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Nonlinear Adaptive Controller for Robot Manipulator (로봇의 비선형 적응제어기 개발에 관한 연구)

  • 박태욱
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.04a
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    • pp.419-423
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    • 1996
  • These days, industrial robots are required to have high speed and high precision in doing various tasks. Recently, the adaptive control algorithms for those nonlinear robots have been developed. With spatial vector space, these adaptive algorithms including recursive implementation are simply described. Without sensing joint acceleration and computing the inversion of inertia matrix, these algorithms which include P.D. terms and feedforward terms have global tracking convergence. In this paper, the feasibility of the proposed control method is illustrated by applying to 2 DOF SCARA robot in DSP(Digital Signal Processing).

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A Study on Signal Parameters Estimation via Nonlinear Minimization

  • Jeong, Jung-Sik
    • Journal of Navigation and Port Research
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    • v.28 no.4
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    • pp.305-309
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    • 2004
  • The problem for parameters estimation of the received signals impinging on array sensors has long been of great research Interest in a great variety of applications, such as radar, sonar, and land mobile communications systems. Conventional subspace-based algorithms, such as MUSIC and ESPRIT, require an extensive computation of inverse matrix and eigen-decomposition In this paper, we propose a new parameters estimation algorithm via nonlinear minimization, which is simplified computationally and estimates signal parameters simultaneously.

The Design of Web Tension Control System Using a Nonlinear Feedback (비선형 궤환을 이용한 장력 제어 시스템 설계)

  • Oh, Seung-Rohk
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.55 no.1
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    • pp.14-16
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    • 2006
  • We consider a web transport system. The objective of this paper is to design the controller such that desired tension and processing on web transport system. We propose the new design method hick is independent with operating condition. The proposed method used a nonlinear feedback to transform to linear system. We show a performance of controller via the simulation.

Optimal Design of Nonlinear Hydraulic Engine Mount

  • Ahn Young Kong;Song Jin Dae;Yang Bo-Suk;Ahn Kyoung Kwan;Morishita Shin
    • Journal of Mechanical Science and Technology
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    • v.19 no.3
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    • pp.768-777
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    • 2005
  • This paper shows that the performance of a nonlinear fluid engine mount can be improved by an optimal design process. The property of a hydraulic mount with inertia track and decoupler differs according to the disturbance frequency range. Since the excitation amplitude is large at low excitation frequency range and is small at high excitation frequency range, mathematical model of the mount can be divided into two linear models. One is a low frequency model and the other is a high frequency model. The combination of the two models is very useful in the analysis of the mount and is used for the first time in the optimization of an engine mount in this paper. Normally, the design of a fluid mount is based on a trial and error approach in industry because there are many design parameters. In this study, a nonlinear mount was optimized to minimize the transmissibilities of the mount at the notch and the resonance frequencies for low and high-frequency models by a popular optimization technique of sequential quadratic programming (SQP) supported by $MATLAB^{(R)}$subroutine. The results show that the performance of the mount can be greatly improved for the low and high frequencies ranges by the optimization method.

Low Dimensional Modeling and Synthesis of Head-Related Transfer Function (HRTF) Using Nonlinear Feature Extraction Methods (비선형 특징추출 기법에 의한 머리전달함수(HRTF)의 저차원 모델링 및 합성)

  • Seo, Sang-Won;Kim, Gi-Hong;Kim, Hyeon-Seok;Kim, Hyeon-Bin;Lee, Ui-Taek
    • The Transactions of the Korea Information Processing Society
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    • v.7 no.5
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    • pp.1361-1369
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    • 2000
  • For the implementation of 3D Sound Localization system, the binaural filtering by HRTFs is generally employed. But the HRTF filter is of high order and its coefficients for all directions have to be stored, which imposes a rather large memory requirement. To cope with this, research works have centered on obtaining low dimensional HRTF representations without significant loss of information and synthesizing the original HRTF efficiently, by means of feature extraction methods for multivariate dat including PCA. In these researches, conventional linear PCA was applied to the frequency domain HRTF data and using relatively small number of principal components the original HRTFs could be synthesized in approximation. In this paper we applied neural network based nonlinear PCA model (NLPCA) and the nonlinear PLS repression model (NLPLS) for this low dimensional HRTF modeling and analyze the results in comparison with the PCA. The NLPCA that performs projection of data onto the nonlinear surfaces showed the capability of more efficient HRTF feature extraction than linear PCA and the NLPLS regression model that incorporates the direction information in feature extraction yielded more stable results in synthesizing general HRTFs not included in the model training.

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Fuzzy Rule Reduction Algorithms and the Reconstruction of Fuzzy System using Decomposition of Nonlinear Functions (비선형 함수의 분해를 이용한 퍼지시스템의 재구성과 퍼지규칙수 줄임 알고리즘)

  • 유병국
    • Journal of the Institute of Convergence Signal Processing
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    • v.2 no.2
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    • pp.95-102
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    • 2001
  • Fuzzy system is capable of uniformly approximating any nonlinear function over compact input space. The applications of fuzzy system, however, have been primarily limited by the need for large number of fuzzy rules, in particular, for the high-order nonlinear system. In this paper, we propose the reconstruction methods of fuzzy systems, parallel type and cascade, based on the decomposition of some classes of high-order nonlinear functions. Using the both types appropriately, we can reduce the number of fuzzy rules geometrically. It can be applied to the fuzzy system that has an online adaptive structure. Two examples of adaptive fuzzy sliding mode control are shown in the computer simulations to verify the validity of the proposed algorithm.

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Parallel Implementation of Nonlinear Analysis Program of PSC Frame Using MPI (MPI를 이용한 PSC 프레임 비선형해석 프로그램의 병렬화)

  • 이재석;최규천
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2001.04a
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    • pp.61-68
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    • 2001
  • A parallel nonlinear analysis program of prestressed concrete frame is migrated on a PC cluster system and a massively parallel processing system, CRAY T3E system, using MPI. The PC cluster system is configured with Pentium Ⅲ class PCs and fast ethernet. The CRAY T3E system is composed of a set of nodes each containing one Processing Element (PE), a memory subsystem and its distributed memory interconnect network. Parallel computing algorithms are implemented on element-wise processing parts including the calculation of stiffness matrix, element stresses and determination of material states, check of material failure and calculation of unbalanced loads. Parallel performance of the migrated program is evaluated through typical numerical examples.

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