• Title, Summary, Keyword: Complex analysis

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Blind modal identification of output-only non-proportionally-damped structures by time-frequency complex independent component analysis

  • Nagarajaiah, Satish;Yang, Yongchao
    • Smart Structures and Systems
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    • v.15 no.1
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    • pp.81-97
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    • 2015
  • Recently, a new output-only modal identification method based on time-frequency independent component analysis (ICA) has been developed by the authors and shown to be useful for even highly-damped structures. In many cases, it is of interest to identify the complex modes of structures with non-proportional damping. This study extends the time-frequency ICA based method to a complex ICA formulation for output-only modal identification of non-proportionally-damped structures. The connection is established between complex ICA model and the complex-valued modal expansion with sparse time-frequency representation, thereby blindly separating the measured structural responses into the complex mode matrix and complex-valued modal responses. Numerical simulation on a non-proportionally-damped system, laboratory experiment on a highly-damped three-story frame, and a real-world highly-damped base-isolated structure identification example demonstrate the capability of the time-frequency complex ICA method for identification of structures with complex modes in a straightforward and efficient manner.

Safety Analysis and Design Model for a Complex System like ATM(Air Traffic Management) System (ATM(Air Traffic Management) 시스템과 같은 복잡 시스템의 안전 분석 및 설계 모델)

  • Park, Joong-Yong
    • Journal of the Korea Society of Systems Engineering
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    • v.3 no.1
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    • pp.27-31
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    • 2007
  • A complex system like ATM(Air Traffic Management) has safety problem emerging from complex interactions between systems. In complex systems, malfunctions of components are not the only causes of critical accidents. To resolve this problem many researchers have proposed new safety analysis models for complex systems. This research is a way of improving safety analysis model focusing on systems engineering design model for ATM.

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A Study on the Design Factors of Complex Damper for Ventilation and Fire Protection (환기 및 소방용 복합댐퍼의 설계인자에 관한 연구)

  • Lee, Dong-Myung
    • Fire Science and Engineering
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    • v.25 no.4
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    • pp.42-47
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    • 2011
  • This study carried out the design and analysis of complex damper as basis study for development of complex damper for ventilation and fire protection. This study established design and analysis theory of complex damper based on process, kinematics mechanism and mechanism modelling of complex damper. And this study established engineering data construction and a source technology that can design each element of complex damper through motion analysis simulation based on design and analysis theory. Therefore, it got result that can apply comprehensively in development of complex damper for ventilation and fire protection from this study. Also, it sees that can ready control means and technological countermeasure of smoke to developed of complex damper with this study.

The Short Time Spectra Analysis System Using The Complex LMS Algorithm and It's Applications

  • Umemoto, Toshitaka;Fujisawa, Shoichiro;Yoshida, Takeo
    • 제어로봇시스템학회:학술대회논문집
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    • pp.58-63
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    • 1998
  • B.Widrow established fundamental relations between the least-mean-square (LMS) algorithm and the digital Fourier transform[1]. By extending these relations, we proposed the short time spectra analysis system using the LMS algorithm[2]. In that paper, we used the normal LMS algorithm on the thought of dealing with only real analytical signal. This algorithm minimizes the real mean-square by recursively altering the complex weight vector at each sampling instant. But, the short time spectra analysis sometimes deals with the complex signal that is outputted from complex analog filter. So, in order to optimize and develop this methods, furthermore it is necessary to derive an algorithm for the complex analytical signal. In this paper, we first discuss the new adaptive system for the spectra analysis using the complex LMS algorithm and then derive convergence condition, time constant of coefficient adjustment and frequency resolution by extending the discussion. Finally, the effectiveness of the proposed method is experimentally demonstrated by applying it to the measurement of transfer performance on complex analog filter.

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ABSTRACT HARMONIC ANALYSIS OVER SPACES OF COMPLEX MEASURES ON HOMOGENEOUS SPACES OF COMPACT GROUPS

  • Farashahi, Arash Ghaani
    • Bulletin of the Korean Mathematical Society
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    • v.54 no.4
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    • pp.1229-1240
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    • 2017
  • This paper presents a systematic study of the abstract harmonic analysis over spaces of complex measures on homogeneous spaces of compact groups. Let G be a compact group and H be a closed subgroup of G. Then we study abstract harmonic analysis of complex measures over the left coset space G/H.

On the didactical analysis of complex numbers (복소수 개념의 교수학적 분석)

  • Yoo, Yoon-Jae
    • Journal for History of Mathematics
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    • v.21 no.4
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    • pp.141-152
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    • 2008
  • In this article, the didactical analysis of complex numbers was explored in the context of mathematical connection. The result of the analysis can provide the useful tools for problem solving. The article shows that the complex numbers system plays the key roles in the school mathematics.

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ON NUMERICAL PROPERTIES OF COMPLEX SYMMETRIC HOUSEHOLDER MATRICES

  • Smoktunowicz, Alicja;Grabarski, Adam
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.7 no.2
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    • pp.51-64
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    • 2003
  • Analysis is given of construction and stability of complex symmetric analogues of Householder matrices, with applications to the eigenproblem for such matrices. We investigate numerical properties of the deflation of complex symmetric matrices by using complex symmetric Householder transformations. The proposed method is very similar to the well-known deflation technique for real symmetric matrices (Cf. [16], pp. 586-595). In this paper we present an error analysis of one step of the deflation of complex symmetric matrices.

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Complex Features by Independent Component Analysis (독립성분분석에 의한 복합특징 형성)

  • 오상훈
    • Proceedings of the Korea Contents Association Conference
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    • pp.351-355
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    • 2003
  • Neurons in the mammalian visual cortex can be classified into the two main categories of simple cells and complex cells based on their response properties. Here, we find the complex features corresponding to the response of complex cells by applying the unsupervised independent component analysis network to input images. This result will be helpful to elucidate the information processing mechanism of neurons in primary visual cortex.

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A Study on Organic Farm's Actual Condition of Promoting Complex Industrialization and Classification Using Changes after Promoting (유기농산물 생산농가의 복합산업화 추진 실태 및 추진 후 변화를 이용한 농가 유형화 연구)

  • Sung, Ji-Eun;Kim, Chang-Ho;Jeong, Jin-Gu
    • Korean Journal of Organic Agriculture
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    • v.25 no.1
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    • pp.1-22
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    • 2017
  • The purpose of this research is to analysis actual condition of promoting complex industrialization and changes after promoting, and then to classify organic farmer using cluster analysis based on delineated organic farmer's changes factors. This study also aims to investigate differences in socioeconomic characteristics and behavioral intentions among classified groups of organic farmer's changes. Data were obtained by questionnaire. From the factor analysis, four factors were derived as "Economics", "Public benefit", "Environment and philosophical values" and "Establishing management and the regional bedrock". From the cluster analysis, three cluster were derived as "group that has a positive awareness of promoting complex industry", "group that has a negative awareness of promoting complex industry" and "unstable management and a regional base". And the three classifications were significantly different in the satisfaction and behavioral intentions.

Discretization technique for stability analysis of complex slopes

  • Hou, Chaoqun;Zhang, Tingting;Sun, Zhibin;Dias, Daniel;Li, Jianfei
    • Geomechanics and Engineering
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    • v.17 no.3
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    • pp.227-236
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    • 2019
  • In practice, the natural slopes are frequently with soils of spatial properties and irregular features. The traditional limit analysis method meets an inherent difficulty to deal with the stability problem for such slopes due to the normal condition in the associated flow rule. To overcome the problem, a novel technique based on the upper bound limit analysis, which is called the discretization technique, is employed for the stability evaluation of complex slopes. In this paper, the discretization mechanism for complex slopes was presented, and the safety factors of several examples were calculated. The good agreement between the discretization-based and previous results shows the accuracy of the proposed mechanism, proving that it can be an alternative and reliable approach for complex slope stability analysis.