• Title/Summary/Keyword: hybrid linear analysis

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Design of multimode E-plane corugated monopulse horn for linear phased array feeder (선형 위상배열 급전기에서 저부엽 모노펄스 패턴을 얻기 위한 다중모드 E-면 주름혼의 설계)

  • 김찬홍;이용희;홍동희
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.11
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    • pp.52-59
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    • 1996
  • This paper presents a monopulse feed structure with low sidelobe monopulse pattern, which consists of a E-plane corrugated horn and a unfiorm pick-up aperture power divider. Tfhe design methods and epxerimental resutls of the E-plane corrugated feeder are described. Modified hybrid mode analysis and GSM (generalized scattering matrix) methods are introduced to design the E-plane corrugated feed horns. The 24-port corrugated feeder is designed using modified hybrid mode analysis initially and verified using GSM methods. Measurement results show that this feeder has low return loss and sidelobe level at sum and difference channel, respectively.

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Non-conventional formulations for the finite element method

  • de Freitas, J.A. Teixeira;de Almeida, J.P. Moitinho;Peraira, E.M.B. Ribeiro
    • Structural Engineering and Mechanics
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    • v.4 no.6
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    • pp.655-678
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    • 1996
  • The paper reports on alternative hybrid/mixed formulations being developed by the Structural Analysis Research Group of Institute Superior T$\acute{e}$cnico. These formulations open the scope and increase the power of the finite element method by allowing different fields to be independently approximated, within certain consistency criteria, and by enhancing the use of a wide range of approximation functions. They have been applied to the analysis of 2-D problems, laminar structures and solids, using different constitutive relations, both in quasi-static and dynamic regimes. The fundamental properties of the formulations are identified and assessed and their performance is illustrated using simple, linear applications.

Characteristics and design parameter deduction of hybrid thrust magnetic bearing (하이브리드 스러스트 마그네틱 베어링의 설계 파라미터 도출 및 특성해석)

  • Jang, Seok-Myeong;Lee, Un-Ho;Ko, Kyoung-Jin;Choi, Ji-Hwan;Sung, So-Young;Lee, Yong-Bok
    • Proceedings of the KIEE Conference
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    • 2009.04b
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    • pp.52-54
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    • 2009
  • This paper deals with design parameters deduction and analysis of hybrid magnetic bearing. Using the solutions obtained from equivalent magnetic circuit, we predict the electromagnetic characteristics from permanent magnet and electromagnet and obtain the initial parameters. And then, using non-linear finite element analysis, a detailed design is performed considering saturation and asymmetry of flux density at the surface in order to meet requirements.

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Multi-DOF Real-time Hybrid Dynamic Test of a Steel Frame Structure (강 뼈대 구조물의 다자유도 실시간 하이브리드 동적 실험)

  • Kim, Sehoon;Na, Okpin;Kim, Sungil
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.2
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    • pp.443-453
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    • 2013
  • The hybrid test is one of the most advanced test methods to predict the structural dynamic behavior with the interaction between a physical substructure and a numerical modeling in the hybrid control system. The purpose of this study is to perform the multi-directional dynamic test of a steel frame structure with the real-time hybrid system and to evaluate the validation of the results. In this study, FEAPH, nonlinear finite element analysis program for hybrid only, was developed and the hybrid control system was optimized. The inefficient computational time was improved with a fixed number iteration method and parallel computational techniques used in FEAPH. Furthermore, the previously used data communication method and the interface between a substructure and an analysis program were simplified in the control system. As the results, the total processing time in real-time hybrid test was shortened up to 10 times of actual measured seismic period. In order to verify the accuracy and validation of the hybrid system, the linear and nonlinear dynamic tests with a steel framed structure were carried out so that the trend of displacement responses was almost in accord with the numerical results. However, the maximum displacement responses had somewhat differences due to the analysis errors in material nonlinearities and the occurrence of permanent displacements. Therefore, if the proper material model and numerical algorithms are developed, the real-time hybrid system could be used to evaluate the structural dynamic behavior and would be an effective testing method as a substitute for a shaking table test.

Hybrid nonlinear control of a tall tower with a pendulum absorber

  • Orlando, Diego;Goncalves, Paulo B.
    • Structural Engineering and Mechanics
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    • v.46 no.2
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    • pp.153-177
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    • 2013
  • Pendulums can be used as passive vibration control devices in several structures and machines. In the present work, the nonlinear behavior of a pendulum-tower system is studied. The tower is modeled as a bar with variable cross-section with concentrated masses. First, the vibration modes and frequencies of the tower are obtained analytically. The primary structure and absorber together constitute a coupled system which is discretized as a two degrees of freedom nonlinear system, using the normalized eigenfunctions and the Rayleigh-Ritz method. The analysis shows the influence of the geometric nonlinearity of the pendulum absorber on the response of the tower. A parametric analysis also shows that, with an appropriate choice of the absorber parameters, a pendulum can decrease the vibration amplitudes of the tower in the main resonance region. The results also show that the pendulum nonlinearity cannot be neglected in this type of problem, leading to multiplicity of solutions, dynamic jumps and instability. In order to improve the effectiveness of the control during the transient response, a hybrid control system is suggested. The added control force is implemented as a non-linear variable stiffness device based on position and velocity feedback. The obtained results show that this strategy of nonlinear control is attractive, has a good potential and can be used to minimize the response of slender structures under various types of excitation.

Capillary Electrochromatography with Liquid Crystal Crown Ether Modified Hybrid Silica Monolith for Analysis of Imidacloprid and Carbendazim in Tomatoes

  • Wang, Mingming;Feng, Rui;Shen, Jing;Chen, Hao;Zeng, Zhaorui
    • Bulletin of the Korean Chemical Society
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    • v.33 no.7
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    • pp.2224-2228
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    • 2012
  • This study describes the ability of capillary electrochromatography (CEC) for the determination of imidacloprid and carbendazim in tomato samples. A novel liquid crystal crown ether modified hybrid silica monolithic column was synthesized, characterized and developed as separation column for the first time. Baseline separation of imidacloprid and carbendazim could be achieved using a mobile phase containing 90% (v/v) 20 mmol/L phosphate buffer (pH 7.0) and 10% (v/v) acetonitrile. The matrix matched calibration curves were linear with correlation coefficient $r^2$ > 0.9998 in the range of 0.20-10.00 mg/L. The limits of detection for imidacloprid and carbendazim were 0.061 and 0.15 mg/kg, respectively, which were below the maximum residue limits established by the European Union as well as Codex Alimentarius. Average recoveries for imidacloprid and carbendazim varied from 101.6-108.0% with relative standard deviations lower than 6.3%. This method was applied to the analysis of tomatoes collected from local markets.

Verification of Hybrid Structural Test Technique by Shaking Table Test of a Linear 2-Dimensional Frame Model (소형선형 평면뼈대모형의 진동대실험을 통한 하이브리드실험 기법의 검증)

  • Cho, Sung-Min;Choi, In-Gyu;Jung, Dae-Sung;Kim, Chul-Young
    • Journal of the Earthquake Engineering Society of Korea
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    • v.14 no.6
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    • pp.33-43
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    • 2010
  • This paper deals with the hybrid structural test technique which has been introduced and studied currently in Korea. In this study, a Mini-MOST system which was developed as a part of NEES research was modified and improved to reduce the total simulation time to half of the original system. Using the proposed system together with the 2 dimensional small steel frame specimen, the validity and efficiency of the hybrid test technique is investigated. Even though the hybrid test has been developed as an alternative to the shaking table test and has been studied and applied for a long time in several countries, no attempt has been made to compare it directly with the shaking table test. Therefore, in this study, the hybrid test results are compared with those of the shaking table test as well as with a numerical simulation for the verification of hybrid test. From the comparison and analysis of the test results, it is concluded that the hybrid test can simulate the actual seismic behavior of structural systems very accurately and it can be a good alternative to the shaking table test.

Analysis of Hybrid Additive Cellular Automata (하이브리드 가산 셀룰라 오토마타의 분석)

  • Cho, Sung-Jin;Choi, Un-Sook;Kim, Han-Doo;Hwang, Yoon-Hee;Kim, Jin-Gyoung;Kim, Bong-Soo
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2008.05a
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    • pp.221-224
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    • 2008
  • Anghelescu et al. proposed a block cryptosystem based on 8-cell hybrid additive cellular automata with cycle length 8 using state transition rules 51, 60 (or 102). All states must divided into the same cycles in the diagram of the cellular automata. But there exist cellular automata which don't satisfy this condition in Anghelescu et al.'s cryptosystem. In this paper we analyze hybrid additive cellular automata and propose an improved method.

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Substructuring-based Structural Reanalysis by Multilevel Hybrid Approximation (다단계 혼성근사화에 의한 부구조화 기반 구조 재해석)

  • 황진하;김경일;이학술
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.12 no.3
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    • pp.397-406
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    • 1999
  • A new solution procedure for approximate reanalysis, using the staged hybrid methods with substructuring, is proposed in this study. Displacements are calculated with two step mixed procedures. First step is to introduce the conservative approximation, which is a hybrid form of the linear and reciprocal approximation, as local approximation. In the next step, it is combined with the global approximation by reduced basis approach. Stresses are evaluated from the displacements by matrix transformation. The quality of reanalyzed quantities can be greatly improved through these staged hybrid approximations, specially for large changes in the design. Overall procedures are based on substructuring scheme. Several numerical examples illustrate the validity and effectiveness of the proposed methods.

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Fabrication of Organic-Inorganic Nano Hybrid Superlattice Thin Films by Molecular Layer Deposition

  • Cho, Bo-Ram;Yang, Da-Som;Sung, Myung-M.
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.115-115
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    • 2011
  • Nano hybrid superlattices consisting of organic and inorganic components have great potential for creation of new types of functional material by utilizing the wide variety of properties which differ from their constituents. They provide the opportunity for developing new materials with new useful properties. Herein, we fabricated new type of organic-inorganic nano hybrid superlattice thin films by a sequential, self-limiting surface chemistry process known as molecular layer depostion (MLD) combined with atomic layer deposition (ALD). An organic layer was formed at $150^{\circ}C$ using MLD with repeated sequintial adsorption of Hydroquinone and Titanium tetrachloride. A $TiO_2$ inorganic nanolayer was deposited at the same temperature using ALD with alternating surface-saturating reactions of Titanium tetrachloride and water. Using UV-Vis spectroscopy, we confirmed visible light absorption by LMCT. And FTIR spectroscopy and XPS were employed to determine the chemical composition. Ellipsometry and TEM analysis were also used to confirm linear growth of the film versus number of MLD cycles at all same temperature. In addition, p-n junction diodes domonstrated in this study suggest that the film can be suitable for n-type semiconductors.

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