• Title/Summary/Keyword: large square

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Analysis of the Levy Mutation Operations in the Evolutionary prograamming using Mean Square Displacement and distinctness (평균변화율 및 유일성을 통한 진화 프로그래밍에서 레비 돌연변이 연산 분석)

  • Lee, Chang-Yong
    • Journal of KIISE:Software and Applications
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    • v.28 no.11
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    • pp.833-841
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    • 2001
  • Abstract In this work, we analyze the Levy mutation operations based on the Levy probability distribution in the evolutionary programming via the mean square displacement and the distinctness. The Levy probability distribution is characterized by an infinite second moment and has been widely studied in conjunction with the fractals. The Levy mutation operators not only generate small varied offspring, but are more likely to generate large varied offspring than the conventional mutation operators. Based on this fact, we prove mathematically, via the mean square displacement and the distinctness, that the Levy mutation operations can explore and exploit a search space more effectively. As a result, one can get better performance with the Levy mutation than the conventional Gaussian mutation for the multi-valued functional optimization problems.

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Characteristics of Large Area ITO/PET Fabricated by Vacuum Web Coater (진공 웹코터로 제작된 대면적 ITO/PET의 특성 연구)

  • Kim, Ji-Hwan;Park, Dong-Hee;Kim, Jong-Bin;Byun, Dong-Jin;Choi, Won-Kook
    • Korean Journal of Materials Research
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    • v.17 no.10
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    • pp.516-520
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    • 2007
  • Indium tin oxide, which is used as transparent conducting layer in flexible device, is deposited on PET film by a magnetron sputtering in 300 mm wide roll-to-roll process (vacuum web coating). Sheet resistance, specific resistance and transmittance is differed by sputtering parameters such as working pressures, oxygen partial pressure, and thickness of ITO layer. ITO layer is deposited about 90 nm at roll speed of 0.24 m/min and its sputtering power is 3 kW. From the XRD spectrum deposited ITO layer is verified as amorphous. Under working pressure varied from $3{\times}10^{-4}\;Torr$ to $2{\times}10^{-3}\;Torr$, sheet resistance is lowest at the working pressure of $1{\times}10^{-3}\;Torr$ and its value is from $110\;{\Omega}/{\square}$ to $260\;{\Omega}/{\square}$ at the thickness of 90 nm. Oxygen partial pressure also varies sheet resistance and is optimized at the regime from 0.2% ($1.8{\times}10^{-6}\;Torr$) to 0.6% ($6{\times}10^{-6}\;Torr$). In this oxygen partial pressure sheet resistance is lower than $150\;{\Omega}/{\square}$. As ITO layer thickness increases, sheet resistance decreases down to $21\;{\Omega}/{\square}$ and specific resistance is about $7.5{\times}10.4{\Omega}cm$ in 340 nm thickness ITO layer. Transmittance is measured at the wavelength of 550 nm and is about 90% for 180 nm thickness ITO/PET.

3D Numerical investigation of a rounded corner square cylinder for supercritical flows

  • Vishwanath, Nivedan;Saravanakumar, Aditya K.;Dwivedi, Kush;Murthy, Kalluri R.C.;Gurugubelli, Pardha S.;Rajasekharan, Sabareesh G.
    • Wind and Structures
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    • v.35 no.1
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    • pp.55-66
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    • 2022
  • Tall buildings are often subjected to steady and unsteady forces due to external wind flows. Measurement and mitigation of these forces becomes critical to structural design in engineering applications. Over the last few decades, many approaches such as modification of the external geometry of structures have been investigated to mitigate wind-induced load. One such proven geometric modification involved the rounding of sharp corners. In this work, we systematically analyze the impact of rounded corner radii on the reducing the flow-induced loading on a square cylinder. We perform 3-Dimensional (3D) simulations for high Reynolds number flows (Re=1 × 105) which are more likely to be encountered in practical applications. An Improved Delayed Detached Eddy Simulation (IDDES) method capable of capturing flow accurately at large Reynolds numbers is employed in this study. The IDDES formulation uses a k-ω Shear Stress Transport (SST) model for near-wall modelling that prevents mesh-induced separation of the boundary layer. The effects of these corner modifications are analyzed in terms of the resulting variations in the mean and fluctuating components of the aerodynamic forces compared to a square cylinder with no geometric changes. Plots of the angular distribution of the mean and fluctuating coefficient of pressure along the square cylinder's surface illustrate the effects of corner modifications on the different parts of the cylinder. The windward corner's separation angle was observed to decrease with an increase in radius, resulting in a narrower and longer recirculation region. Furthermore, with an increase in radius, a reduction in the fluctuating lift, mean drag, and fluctuating drag coefficients has been observed.

Compressive behavior of concrete-filled square stainless steel tube stub columns

  • Dai, Peng;Yang, Lu;Wang, Jie;Ning, Keyang;Gang, Yi
    • Steel and Composite Structures
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    • v.42 no.1
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    • pp.91-106
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    • 2022
  • Concrete-filled square stainless steel tubes (CFSSST), which possess relatively large flexural stiffness, high corrosion resistance and require simple joint configurations and low maintenance cost, have a great potential in constructional applications. Despite that the use of stainless steel may result in high initial cost compared to their conventional carbon steel counterparts, the whole-life cost of CFSSST is however considered to be lower, which offers a competitive choice in engineering practice. In this paper, a comprehensive experimental and numerical program on 24 CFSSST stub column specimens, including 3 austenitic and 3 duplex stainless steel square hollow section (SHS) stub columns and 9 austenitic and 9 duplex CFSSST stub columns, has been carried out. Finite element (FE) models were developed to be used in parametric analysis to investigate the influence of the tube thickness and concrete strength on the ultimate capacities more accurately. Comparisons of the experimental and numerical results with the predictions made by design guides ACI 318, ANSI/AISC 360, Eurocode 4 and GB 50936 have been performed. It was found that these design methods generally give conservative predictions to the ultimate capacities of CFSSST stub columns. Improved calculation methods, developed based on the Continuous Strength Method, have been proposed to provide more accurate estimations of the ultimate resistances of CFSSST stub columns. The suitability of these proposals has been validated by comparison with the test results, where a good agreement between the predictions and the test results have been achieved.

Categorized VSSLMS Algorithm (Categorized 가변 스텝 사이즈 LMS 알고리즘)

  • Kim, Seon-Ho;Chon, Sang-Bae;Lim, Jun-Seok;Sung, Koeng-Mo
    • The Journal of the Acoustical Society of Korea
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    • v.28 no.8
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    • pp.815-821
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    • 2009
  • Information processing in variable and noisy environments is usually accomplished by means of adaptive filters. Among various adaptive algorithms, Least Mean Square (LMS) has become the most popular for its robustness, good tracking capabilities and simplicity, both in terms of computational load and easiness of implementation. In practical application of the LMS algorithm, the most important key parameter is the Step Size. As is well known, if the Step Size is large, the convergence rate of the algorithm will be rapid, but the steady state mean square error (MSE) will increase. On the other hand, if the Step Size is small, the steady state MSE will be small, but the convergence rate will be slow. Many researches have been proposed to alleviate this drawback by using a variable Step Size. In this paper, a new variable Step Size LMS(VSSLMS) called Categorized VSSLMS (CVSSLMS) is proposed. CVSSLMS updates the Step Size by categorizing the current status of the gradient, hence significantly improves the convergence rate. The performance of the proposed algorithm was verified from the view point of convergence rate, Excessive Mean Square Error(EMSE), and complexity through experiments.

Vibration behavior of large span composite steel bar truss-reinforced concrete floor due to human activity

  • Cao, Liang;Li, Jiang;Zheng, Xing;Chen, Y. Frank
    • Steel and Composite Structures
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    • v.37 no.4
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    • pp.391-404
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    • 2020
  • Human-induced vibration could present a serious serviceability problem for large-span and/or lightweight floors using the high-strength material. This paper presents the results of heel-drop, jumping, and walking tests on a large-span composite steel rebar truss-reinforced concrete (CSBTRC) floor. The effects of human activities on the floor vibration behavior were investigated considering the parameters of peak acceleration, root-mean-square acceleration, maximum transient vibration value (MTVV), fundamental frequency, and damping ratio. The measured field test data were validated with the finite element and theoretical analysis results. A comprehensive comparison between the test results and current design codes was carried out. Based on the classical plate theory, a rational and simplified formula for determining the fundamental frequency for the CSBTRC floor is derived. Secondly, appropriate coefficients (βrp) correlating the MTVV with peak acceleration are suggested for heel-drop, jumping, and walking excitations. Lastly, the linear oscillator model (LOM) is adopted to establish the governing equations for the human-structure interaction (HSI). The dynamic characteristics of the LOM (sprung mass, equivalent stiffness, and equivalent damping ratio) are determined by comparing the theoretical and experimental acceleration responses. The HSI effect will increase the acceleration response.

Gaze Detection by Wearable Eye-Tracking and NIR LED-Based Head-Tracking Device Based on SVR

  • Cho, Chul Woo;Lee, Ji Woo;Shin, Kwang Yong;Lee, Eui Chul;Park, Kang Ryoung;Lee, Heekyung;Cha, Jihun
    • ETRI Journal
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    • v.34 no.4
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    • pp.542-552
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    • 2012
  • In this paper, a gaze estimation method is proposed for use with a large-sized display at a distance. Our research has the following four novelties: this is the first study on gaze-tracking for large-sized displays and large Z (viewing) distances; our gaze-tracking accuracy is not affected by head movements since the proposed method tracks the head by using a near infrared camera and an infrared light-emitting diode; the threshold for local binarization of the pupil area is adaptively determined by using a p-tile method based on circular edge detection irrespective of the eyelid or eyelash shadows; and accurate gaze position is calculated by using two support vector regressions without complicated calibrations for the camera, display, and user's eyes, in which the gaze positions and head movements are used as feature values. The root mean square error of gaze detection is calculated as $0.79^{\circ}$ for a 30-inch screen.

Numerical investigations of pile load distribution in pile group foundation subjected to vertical load and large moment

  • Ukritchon, Boonchai;Faustino, Janine Correa;Keawsawasvong, Suraparb
    • Geomechanics and Engineering
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    • v.10 no.5
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    • pp.577-598
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    • 2016
  • This paper presents a numerical study of pile force distribution in a pile group foundation subjected to vertical load and large moment. The physical modeling of a pile foundation for a wind turbine is analyzed using 3D finite element software, PLAXIS 3D. The soil profile consists of several clay layers, which are modeled as Mohr-Coulomb material in an undrained condition. The piles in the pile group foundation are modeled as special elements called embedded pile elements. To model the problem of a pile group foundation, a small gap is created between the pile cap and underlying soil. The pile cap is modeled as a rigid plate element connected to each pile by a hinge. As a result, applied vertical load and large moment are transferred only to piles without any load sharing to underlying soil. Results of the study focus on pile load distribution for the square shape of a pile group foundation. Mathematical expression is proposed to describe pile force distribution for the cases of vertical load and large moment and purely vertical load.

Estimation of A New Initial Parameter for the Lloyd-Max Algorithm (로이드-맥스 알고리즘을 위한 새로운 초기 파라메타의 추정)

  • Eon Kyeong Joo
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.31B no.7
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    • pp.26-32
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    • 1994
  • The Lloyd-Max algorithm is an iterative scheme for design of the minimum mean square error quantizer. It is very simple in concept and easy to program into a computer. However its convergence and accuracy are primarily dependent upon the accuracy of the initial parameter. In this paper, a new initial parameter which converges to a specific value when the number of output levels becomes large is selected. And an estimator using curve fitting techique is suggested. In addition, performance of the proposed method is shown to be superior to that of the existing methods in accuracy and convergence.

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SUMS OF TRIPOTENT AND NILPOTENT MATRICES

  • Abdolyousefi, Marjan Sheibani;Chen, Huanyin
    • Bulletin of the Korean Mathematical Society
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    • v.55 no.3
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    • pp.913-920
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    • 2018
  • Let R be a 2-primal strongly 2-nil-clean ring. We prove that every square matrix over R is the sum of a tripotent and a nilpotent matrices. The similar result for rings of bounded index is proved. We thereby provide a large class of rings over which every matrix is the sum of a tripotent and a nilpotent matrices.