• Title/Summary/Keyword: weighted function

Search Result 749, Processing Time 0.028 seconds

A novel WOA-based structural damage identification using weighted modal data and flexibility assurance criterion

  • Chen, Zexiang;Yu, Ling
    • Structural Engineering and Mechanics
    • /
    • v.75 no.4
    • /
    • pp.445-454
    • /
    • 2020
  • Structural damage identification (SDI) is a crucial step in structural health monitoring. However, some of the existing SDI methods cannot provide enough identification accuracy and efficiency in practice. A novel whale optimization algorithm (WOA) based method is proposed for SDI by weighting modal data and flexibility assurance criterion in this study. At first, the SDI problem is mathematically converted into a constrained optimization problem. Unlike traditional objective function defined using frequencies and mode shapes, a new objective function on the SDI problem is formulated by weighting both modal data and flexibility assurance criterion. Then, the WOA method, due to its good performance of fast convergence and global searching ability, is adopted to provide an accurate solution to the SDI problem, different predator mechanisms are formulated and their probability thresholds are selected. Finally, the performance of the proposed method is assessed by numerical simulations on a simply-supported beam and a 31-bar truss structures. For the given multiple structural damage conditions under environmental noises, the WOA-based SDI method can effectively locate structural damages and accurately estimate severities of damages. Compared with other optimization methods, such as particle swarm optimization and dragonfly algorithm, the proposed WOA-based method outperforms in accuracy and efficiency, which can provide a more effective and potential tool for the SDI problem.

SOME PROPERTIES OF THE BEREZIN TRANSFORM IN THE BIDISC

  • Lee, Jaesung
    • Communications of the Korean Mathematical Society
    • /
    • v.32 no.3
    • /
    • pp.779-787
    • /
    • 2017
  • Let m be the Lebesgue measure on ${\mathbb{C}}$ normalized to $m(D)=1,{\mu}$ be an invariant measure on D defined by $d_{\mu}(z)=(1-{\mid}z{\mid}^2)^{-2}dm(z)$. For $f{\in}L^1(D^n,m{\times}{\cdots}{\times}m)$, Bf the Berezin transform of f is defined by, $$(Bf)(z_1,{\ldots},z_n)={\displaystyle\smashmargin{2}{\int\nolimits_D}{\cdots}{\int\nolimits_D}}f({\varphi}_{z_1}(x_1),{\ldots},{\varphi}_{z_n}(x_n))dm(x_1){\cdots}dm(x_n)$$. We prove that if $f{\in}L^1(D^2,{\mu}{\times}{\mu})$ is radial and satisfies ${\int}{\int_{D^2}}fd{\mu}{\times}d{\mu}=0$, then for every bounded radial function ${\ell}$ on $D^2$ we have $$\lim_{n{\rightarrow}{\infty}}{\displaystyle\smashmargin{2}{\int\int\nolimits_{D^2}}}(B^nf)(z,w){\ell}(z,w)d{\mu}(z)d{\mu}(w)=0$$. Then, using the above property we prove n-harmonicity of bounded function which is invariant under the Berezin transform. And we show the same results for the weighted the Berezin transform in the polydisc.

Implementation and Performance Analysis of FDNN Using Quantization Triangularity Fuzzy Function (양자화 삼각 퍼지 함수를 이용한 FDNN 구현 및 성능 분석)

  • 변오성;이철희;문성용
    • Journal of the Korean Institute of Telematics and Electronics C
    • /
    • v.36C no.11
    • /
    • pp.84-91
    • /
    • 1999
  • In this paper, we could analyze the comparison with applied WFM to the quantization triangularity fuzzy function and triangularity Fuzzy function. In order to improve on a fault which not remove completely noise included image according to a peculiarity of noise, we got to realize FDNN of the high speed weight eliminating noise included image, minimizing the lost of information, obtaining information of suitability owing to applied Fuzzy Algorithm to DBNN of a hierarchical structure. We could analyze the comparison with a power of WFM and FDNN using simulation We could find to superiority the proposed FDNN )n a result which was the comparison of MSE for the boats image.

  • PDF

A study of facial nerve grading system (안면신경기능의 평가방법에 대한 고찰;House-Brackmann scale이후의 New grade)

  • Kim, Mi-Bo;Kim, Ja-Hye;Shin, Sang-Ho;Yoon, Hwa-Jung;Ko, Woo-Shin
    • The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
    • /
    • v.20 no.3
    • /
    • pp.147-160
    • /
    • 2007
  • Background and Objective : The facial nerve grading system proposed by House and Brackmann is most widely accepted for the clinical assessment of facial nerve injury. Because of the limitations and subjectivity of the House-Brackmann scale, several new scales of varying degrees of objectivity and ease of use have been introduced. To assess methods of evaluating the function of the facial nerve that have been introduced over the past 20 years, We compared with the House-Brackmann scale. Method : We referred to the information through Entrez Pubmed and Korean studies information(KSI) from 1985 to 2006 about methods of evaluating facial nerve function. We choose 7 scales that focused on objective and easy of use. Result and conclusion : Sunnybrook scale is a weighted, subjective scale with incorporation of secondary defects into a single composite score. Sunnybrook scale can be recommended over House-Brackmann scale.

  • PDF

LATITUDINAL DISTRIBUTION OF SUNSPOTS AND DURATION OF SOLAR CYCLES

  • CHANG, HEON-YOUNG
    • Journal of The Korean Astronomical Society
    • /
    • v.48 no.6
    • /
    • pp.325-331
    • /
    • 2015
  • We study an association between the duration of solar activity and characteristics of the latitude distribution of sunspots by means of center-of-latitude (COL) of sunspots observed during the period from 1878 to 2008 spanning solar cycles 12 to 23. We first calculate COL by taking the area-weighted mean latitude of sunspots for each calendar month to determine the latitudinal distribution of COL of sunspots appearing in the long and short cycles separately. The data set for the long solar cycles consists of the solar cycles 12, 13, 14, 20, and 23. The short solar cycles include the solar cycles 15, 16, 17, 18, 19, 21, and 22. We then fit a double Gaussian function to compare properties of the latitudinal distribution resulting from the two data sets. Our main findings are as follows: (1) The main component of the double Gaussian function does not show any significant change in the central position and in the full-width-at-half-maximum (FWHM), except in the amplitude. They are all centered at ~ 11° with FWHM of ~ 5°. (2) The secondary component of the double Gaussian function at higher latitudes seems to differ in that even though their width remains fixed at ~ 4°, their central position peaks at ~ 22.1° for the short cycles and at ~ 20.7° for the long cycles with quite small errors. (3) No significant correlation could be established between the duration of an individual cycle and the parameters of the double Gaussian. Finally, we conclude by briefly discussing the implications of these findings on the issue of the cycle 4 concerning a lost cycle.

A Study on Edge Detection Algorithm using Grey Level Converting Function (그레이 레벨 변환 함수를 이용한 에지 검출 알고리즘에 관한 연구)

  • Lee, Chang-Young;Hwang, Yeong-Yeun;Kim, Nam-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
    • /
    • 2015.10a
    • /
    • pp.921-923
    • /
    • 2015
  • Edge in the image includes the size, direction and location of objects. The existing detection methods for detecting this edge is a method using Sobel, Prewitt, Roberts and Laplacian, etc. These existing methods use a fixed weighted mask in order to detect the edge and have somewhat insufficient edge detection characteristics. Therefore in this paper, an algorithm that detects the edge by applying the grey level converting function according to the pixel distribution of local mask was proposed.

  • PDF

Localization of Mobile Robot Based on Radio Frequency Identification Devices (RFID를 이용한 이동로봇의 위치인식기술)

  • Lee Hyun-Jeong;Choi Kyu-Cheon;Lee Min-Cheol;Lee Jang-Myung
    • Journal of Institute of Control, Robotics and Systems
    • /
    • v.12 no.1
    • /
    • pp.41-46
    • /
    • 2006
  • Ubiquitous location based services, offer helpful services anytime and anywhere by using real-time location information of objects based on ubiquitous network. Particularly, autonomous mobile robots can be a solution for various applications related to ubiquitous location based services, e.g. in hospitals, for cleaning, at airports or railway stations. However, a meaningful and still unsolved problem for most applications is to develop a robust and cheap positioning system. A typical example of position measurements is dead reckoning that is well known for providing a good short-term accuracy, being inexpensive and allowing very high sampling rates. However, the measurement always has some accumulated errors because the fundamental idea of dead reckoning is the integration of incremental motion information over time. The other hand, a localization system using RFID offers absolute position of robots regardless of elapsed time. We construct an absolute positioning system based on RFID and investigate how localization technique can be enhanced by RFID through experiment to measure the location of a mobile robot. Tags are placed on the floor at 5cm intervals in the shape of square in an arbitrary space and the accuracy of position measurement is investigated . To reduce the error and the variation of error, a weighting function based on Gaussian function is used. Different weighting values are applied to position data of tags since weighting values follow Gaussian function.

Design Optimization of Axial Flow Fan Using Genetic Algorithm (유전자 알고리즘을 이용한 축류 송풍기 설계최적화)

  • Yoo, In-Tae;Ahn, Cheol-O;Lee, Sang-Hwan
    • 유체기계공업학회:학술대회논문집
    • /
    • 2003.12a
    • /
    • pp.397-403
    • /
    • 2003
  • In an attempt to solve multiobjective optimization problems, weighted sum method is most widely used for the advantage that a designer can consider the relative significance of each object functions by weight values but it can be highly sensitive to weight vector and occasionally yield a deviated optimum from the relative weighting values designer designated because the multiobjective function has the form of simple sum of the product of the weighting values and the object functions in traditional approach. To search the design solution well agree to the designer's weighting values, we proposed new multiobjective function which is the functional of each normalized objective functions and considered to find the design solution comparing the distance between the characteristic line and the ideal optimum. In this study, proposed multiobjective function was applied to design high efficiency and low noise axial flow fan and the result shows this approach will be effective for the case that the qualify of the design can be highly affected by the designer's subjectiveness represented as weighting values in multiobjective design optimization process.

  • PDF

A Study on Edge Detection using Pixel Brightness Transfer Function in Low Light Level Environments (저조도 환경에서 화소의 휘도 변환 함수를 이용한 에지 검출에 관한 연구)

  • Lee, Chang-Young;Kim, Nam-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.19 no.7
    • /
    • pp.1680-1686
    • /
    • 2015
  • Edge detection is an essential preprocessing for most image processing application, and there are several existing detection methods such as Sobel, Roberts, Laplacian, LoG(Laplacian of Gaussian) operators, etc. Those existing edge detection methods have not given satisfactory results since they do not offer enough pixel brightness change in low light level environment. Therefore, in this study new algorithms using brightness transfer function in the preprocessing and for edge detection applying standard deviation and average-weighted local masks are proposed. In addition, the performance of proposed algorithms was evaluated in comparison with the existing edge detection methods such as Sobel, Roberts, Prewitt, Laplacian, LoG operators.

Structural damage identification using an iterative two-stage method combining a modal energy based index with the BAS algorithm

  • Wang, Shuqing;Jiang, Yufeng;Xu, Mingqiang;Li, Yingchao;Li, Zhixiong
    • Steel and Composite Structures
    • /
    • v.36 no.1
    • /
    • pp.31-45
    • /
    • 2020
  • The purpose of this study is to develop an effective iterative two-stage method (ITSM) for structural damage identification of offshore platform structures. In each iteration, a new damage index, Modal Energy-Based Damage Index (MEBI), is proposed to help effectively locate the potential damage elements in the first stage. Then, in the second stage, the beetle antenna search (BAS) algorithm is used to estimate the damage severity of these elements. Compared with the well-known particle swarm optimization (PSO) algorithm and genetic algorithm (GA), this algorithm has lower computational cost. A modal energy based objective function for the optimization process is proposed. Using numerical and experimental data, the efficiency and accuracy of the ITSM are studied. The effects of measurement noise and spatial incompleteness of mode shape are both considered. All the obtained results show that under these influences, the ITSM can accurately identify the true location and severity of damage. The results also show that the objective function based on modal energy is most suitable for the ITSM compared with that based on flexibility and weighted natural frequency-mode shape.