• Title/Summary/Keyword: gradient structure

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Characteristics of Potential Gradient for the Type of Structure Grounding Electrode (구조체 접지전극의 유형에 따른 전위경도 특성)

  • Gil Hyung-Jun;Choi Chun-Seog;Kim Hyang-Kon;Lee Bok-Hee
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.54 no.8
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    • pp.371-377
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    • 2005
  • This paper Presents the Potential gradient characteristics of structure grounding electrode when a test current flows through grounding electrode. In order to analyze the potential gradient of ground surface on structure grounding electrode, the reduced scale model has been used. The potential gradient has been measured and analyzed for types of structure using the hemispherical grounding simulation system in real time. The structures were designed through reducing real buildings and fabricated with four types on a scale of one-one hundred sixty. The supporter was made to put up with weight of structure and could move into vertical, horizontal, rotary direction. When a test current flowed through structure grounding electrodes, ground potential rise was the lowest value at electric cage type(type B). According to resistivity and absorption percentage In concrete attached to structure, the potential distribution of ground surface appeared differently.

Optimal Design of Laminate Composites with Gradient Structure for Weight Reduction

  • Back, Sung-Ki;Kang, Tae-Jin;Lee, Kyung-Woo
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 1999.11a
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    • pp.68-72
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    • 1999
  • In an effort to construct a structure under the design principle of minimal use of materials for maximum performances, a discrete gradient structure has been introduced in laminate composite systems. Using a sequential linear programming method, the gradient structure of composites to maximize the buckling load was optimized in terms of fiber volume fraction and thickness of each layer. Theoretical optimization results were then verified with experimental ones. The buckling load of laminate composite showed maximum value with the outmost [$0^{\circ}$] layer concentrated by almost all the fibers when the ratio of length to width(aspect ratio) was less than 1.0. But when the aspect ratio was 2.0, the optimum was determined in a structure where the thickness and fiber volume fraction were well balanced in each layer. From the optimization of gradient structure, the optimal fiber volume fraction and thickness of each layer were proposed. Experimental results agreed well with the theoretical ones. Gradient structures have also shown an advantage in the weight reduction of composites compared with the conventional homogeneous structures.

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Gradient Structure and Surface Property of Fluorinated Polyacrylate and Polyurethane Latex Blend Films (불소화 폴리아크릴레이트-폴리우레탄 라텍스 혼성필름의 그레디언트 구조와 표면성질)

  • Zhu, Min;Chen, Kun;Zhang, Yufang;Wang, Xiangrongm;Zhou, Xiangdong
    • Polymer(Korea)
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    • v.38 no.3
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    • pp.265-271
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    • 2014
  • In order to investigate the characteristics of the gradient fluorinated polyacrylate and polyurethane latex blend films, the fluorinated polyacrylate emulsion and the polyurethane emulsion were synthesized, and then the both emulsions were blended at a series of ratios. The effects of content of the fluorinated polyacrylate on the gradient structure and surface property of the blended films were assessed by AFM, XPS, SEM-EDX and surface free energy measurements. It appeared that, while the content of the fluorinated polyacrylate latex was up to 30%, the fluorinated polyacrylate particles were selectively gathered on the film-air (F-A) and film-glass (F-G) interfaces at room temperature. When the content of the fluorinated polyacrylate was under 30%, the gradient structure of fluorinated component was not evident. The further increasing of fluorinated polyacrylate in the mixed system facilitated the formation and enlargement of gradient structure, but the adhesion of film decreased a little.

Optimal Design of Laminate Composites with Gradient Structure (경사형 구조 적층복합재료의 최적설계에 관한 연구)

  • 백성기;강태진;이경우
    • Composites Research
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    • v.13 no.2
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    • pp.40-50
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    • 2000
  • In an effort to construct a structure under the design principle of minimal use of materials for maximum performances, a discrete gradient structure has been introduced in laminate composite systems. Using a sequential linear programming method, the gradient structure of composites to maximize the buckling load was optimized in terms of fiber volume fraction and thickness of each layer. The buckling load showed maximum value with the outmost [$0^{\circ}$] layer concentrated by almost all the fibers when the ratio of length to width(aspect ratio) was less than 1.0. But when the aspect ratio was 2.0, the optimum was determined in a structure where the thickness and fiber volume fraction were well-balanced in each layer. From the optimization of gradient structure, the optimal fiber volume fraction and thickness of each layer were proposed. Gradient structures have also shown an advantage in the weight reduction of composites compared with the conventional homogeneous structures.

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Structure Optimization of Solute Molecules via Free Energy Gradient Method

  • Nagaoka, Masataka
    • Bulletin of the Korean Chemical Society
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    • v.24 no.6
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    • pp.805-808
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    • 2003
  • Fundamental ideas of the free energy gradient method are briefly reviewed with three applications: the stable structures of glycine and ammonia-water molecule pair in aqueous solution and the transition state (TS) structure of a Menshutkin reaction $NH_3 + CH_3Cl → CH_3NH_3^+ + Cl^-$ in aqueous solution, which is the first example of full TS optimization of all internal degrees of freedom.

Sensitivita Analysis and Optimal desing of plane Vehicle Frame Structures (평면 차체프레임구조물의 민감도해석 및 최적설계)

  • 이종선
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.5 no.4
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    • pp.74-81
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    • 1996
  • This paper is to estimate sizing design sensitivity of linear and nonlinear vehicle frame structure using structural ananlysis result from ANSYS. Using design sensitivity results, optimal design of plane vehicle frame structure with buckling constraint is carried out the gradient projection method. Optimal design results are compares gradient projection method resrult with SUMT result.

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The Effect of Processing Conditions on the Gradient Pore Structure of Diatomite by Centrifugal Molding (경사 기공 구조를 가지는 규조토의 제조에 원심 분리 성형 공정 변수들이 미치는 영향)

  • Ha, Jang-Hoon;Oh, Eun-Ji;Ahmad, Rizwan;Song, In-Hyuck
    • Journal of Powder Materials
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    • v.19 no.4
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    • pp.304-309
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    • 2012
  • The purpose of our study was to develop the fabrication method of porous diatomite ceramics with a porosity gradient by centrifugal molding. The processing variables of centrifugal molding were derived from Stoke's law of sedimentation, which were the radius of the particles, the acceleration due to centrifugal molding and the dynamic viscosity of the slurry. And these could be controlled by ball-milling conditions, centrifugal conditions, and the addition of methyl cellulose, respectively. The effects of processing conditions on the gradient pore structure of diatomite were investigated by particle size analysis, scanning electron microscope, and mercury porosimeter.

Hybrid adaptive neuro-fuzzy inference system method for energy absorption of nano-composite reinforced beam with piezoelectric face-sheets

  • Lili Xiao
    • Advances in nano research
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    • v.14 no.2
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    • pp.141-154
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    • 2023
  • Effects of viscoelastic foundation on vibration of curved-beam structure with clamped and simply-supported boundary conditions is investigated in this study. In doing so, a micro-scale laminate composite beam with two piezoelectric face layer with a carbon nanotube reinforces composite core is considered. The whole beam structure is laid on a viscoelastic substrate which normally occurred in actual conditions. Due to small scale of the structure non-classical elasticity theory provided more accurate results. Therefore, nonlocal strain gradient theory is employed here to capture both nano-scale effects on carbon nanotubes and microscale effects because of overall scale of the structure. Equivalent homogenous properties of the composite core is obtained using Halpin-Tsai equation. The equations of motion is derived considering energy terms of the beam and variational principle in minimizing total energy. The boundary condition is assumed to be clamped at one end and simply supported at the other end. Due to nonlinear terms in the equations of motion, semi-analytical method of general differential quadrature method is engaged to solve the equations. In addition, due to complexity in developing and solving equations of motion of arches, an artificial neural network is design and implemented to capture effects of different parameters on the inplane vibration of sandwich arches. At the end, effects of several parameters including nonlocal and gradient parameters, geometrical aspect ratios and substrate constants of the structure on the natural frequency and amplitude is derived. It is observed that increasing nonlocal and gradient parameters have contradictory effects of the amplitude and frequency of vibration of the laminate beam.

A new conjugate gradient method for dynamic load identification of airfoil structure with randomness

  • Lin J. Wang;Jia H. Li;You X. Xie
    • Structural Engineering and Mechanics
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    • v.88 no.4
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    • pp.301-309
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    • 2023
  • In this paper, a new modified conjugate gradient (MCG) method is presented which is based on a new gradient regularizer, and this method is used to identify the dynamic load on airfoil structure without and with considering random structure parameters. First of all, the newly proposed algorithm is proved to be efficient and convergent through the rigorous mathematics theory and the numerical results of determinate dynamic load identification. Secondly, using the perturbation method, we transform uncertain inverse problem about force reconstruction into determinate load identification problem. Lastly, the statistical characteristics of identified load are evaluated by statistical methods. Especially, this newly proposed approach has successfully solved determinate and uncertain inverse problems about dynamic load identification. Numerical simulations validate that the newly developed method in this paper is feasible and stable in solving load identification problems without and with considering random structure parameters. Additionally, it also shows that most of the observation error of the proposed algorithm in solving dynamic load identification of deterministic and random structure is respectively within 11.13%, 20%.