• Title, Summary, Keyword: layered approach

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Seismic response analysis of layered soils considering effect of surcharge mass using HFTD approach. Part II: Nonlinear HFTD and numerical examples

  • Saffarian, Mohammad A.;Bagheripour, Mohammad H.
    • Geomechanics and Engineering
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    • v.6 no.6
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    • pp.531-544
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    • 2014
  • Studies of earthquakes over the last 50 years and the examination of dynamic soil behavior reveal that soil behavior is highly nonlinear and hysteretic even at small strains. Nonlinear behavior of soils during a seismic event has a predominant role in current site response analysis approaches. Common approaches to ground response analysis include linear, equivalent linear and nonlinear methods. These methods of ground response analysis may also be categorized into time domain and frequency domain concepts. Simplicity in developing analytical relations and accuracy in considering soils' dynamic properties dependency to loading frequency are benefits of frequency domain analysis. On the other hand, nonlinear methods are complicated and time consuming mainly because of their step by step integrations in time intervals. In part Ι of this paper, governing equations for seismic response analysis of surcharged and layered soils were developed using fundamental of wave propagation theory based on transfer function and boundary conditions. In this part, nonlinear seismic ground response is analyzed using extended HFTD method. The extended HFTD method benefits Newton-Raphson procedure which applies regular iterations and follows soils' fundamental stress-strain curve until convergence is achieved. The nonlinear HFTD approach developed here are applied to some examples presented in this part of the paper. Case studies are carried in which effects of some influencing parameters on the response are investigated. Results show that the current approach is sufficiently accurate, efficient, and fast converging. Discussions on the results obtained are presented throughout this part of the paper.

Layered finite element method in cracking and failure analysis of RC beams and beam-column-slab connections

  • Guan, Hong;Loo, Yew-Chaye
    • Structural Engineering and Mechanics
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    • v.5 no.5
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    • pp.645-662
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    • 1997
  • A nonlinear semi-three-dimensional layered finite element procedure is developed for cracking and failure analysis of reinforced concrete beams and the spandrel beam-column-slab connections of flat plates. The layered element approach takes the elasto-plastic failure behaviour and geometric nonlinearity into consideration. A strain-hardening plasticity concrete model and a smeared steel model are incorporated into the layered element formulation. Further, shear failure, transverse reinforcement, spandrel beams and columns are successfully modelled. The proposed method incorporating the nonlinear constitutive models for concrete and steel is implemented in a finite element program. Test specimens including a series of reinforced concrete beams and beam-column-slab connections of flat plates are analysed. Results confirm the effectiveness and accuracy of the layered procedure in predicting both flexural and shear cracking up to failure.

Principles of Microflap Surgery in Laryngomicrosurgery (후뒤세수술에서 미세피판술의 원칙)

  • Kwon, Tack-Kyun;Son, Hee-Young
    • Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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    • v.21 no.2
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    • pp.105-111
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    • 2010
  • The vibratory or phonating surface of the human vocal folds is a complex layered structure. Benign vocal fold lesions arise primarily within the lamina propria of the vocal folds and produce dysphonia by disrupting the normal layered architecture of the phonating surface. Therefore, treatment is aimed at excision of the lesion with restoration of the normal layered architecture. The core principle of the Microflap approach is that conservative removal of submucosal pathology with preservation of overlying normal epithelium and superficial lamina propria. Microflap approach is an essential component of most phnomicrosurgical procedures and is a challenging surgical task that requires patience, appropriate instrumentation, surgical skill, and experience. The authors reviewed surgical principles of Microflap technique, instrumentation and surgical tips that could be useful for the beginners who tried to try Microflap technique for the treatment of benign vocal fold mucosal lesions.

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Nonlinear Analysis of Reinforced and Prestressed Concrete Shells Using Layered Elements with Drilling DOF

  • Kim Tae-Hoon;Choi Jung-Ho;Kim Woon-Hak;Shin Hyun Mock
    • Journal of the Korea Concrete Institute
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    • v.17 no.4
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    • pp.645-654
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    • 2005
  • This paper presents a nonlinear finite element procedure for the analysis of reinforced and prestressed concrete shells using the four-node quadrilateral flat shell element with drilling rotational stiffness. A layered approach is used to discretize, through the thickness, the behavior of concrete, reinforcing bars and tendons. Using the smeared-crack method, cracked concrete is treated as an orthotropic nonlinear material. The steel reinforcement and tendon are assumed to be in a uni-axial stress state and to be smeared in a layer. The constitutive models, which cover the loading, unloading, and reloading paths, and the developed finite element procedure predicts with reasonable accuracy the behavior of reinforced and prestressed concrete shells subjected to different types of loading. The proposed numerical method fur nonlinear analysis of reinforced and prestressed concrete shells is verified by comparison with reliable experimental results.

Study of Mechanics of Remote Sensing and Exploring Method in Layered Medium

  • Ai-lan, LAN;Sheng-wei, ZHANG;Jing-shan, Jiang
    • Proceedings of the KSRS Conference
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    • pp.1356-1358
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    • 2003
  • In the paper, a method making use of the characteristics of Dyad Green Function (DGF) and Fluctuation-Dissipation Theorem to get the brightness temperature of layered medium is introduced. Based on the approach and the measured data of multi-channel radiometer and Least Square Method (LSM), the thickness of lunar soil can be retrieved. These methods are significant to study on materials on lunar surface.

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Mechanistic examination of pre-exfoliating confinement of surface-functionalized nanobeads within layered silicates

  • Lee, Sang-Soo;Khvan, Svetlana;Kim, Jun-Kyung
    • Proceedings of the Polymer Society of Korea Conference
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    • pp.190-190
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    • 2006
  • The approach used in present work allows achieving highly exfoliated state of layered silicate s through confinement of the charged nanobeads within the gallery of swollen pristine clay. The latter is principally promoted by ion exchange that involves polar functional groups on the surface of nanobeads and sodium cation in the interlayer gallery of layered silicates. Surface functionality of the nanobeads plays crucial role in establishment of strong interactions with silicate surface, and eventually, dispersion of individual silicate nanoplatelets.

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Comparison of Contaminant Transport between the Centrifuge Model and the Advection Dispersion Equation Model

  • Young, Horace-Moo;Kim, Tae-Hyung
    • Journal of Soil and Groundwater Environment
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    • v.8 no.3
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    • pp.8-12
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    • 2003
  • The centrifuge test result on capped sediment was compared to the advection- dispersion equation proposed for one layered to predict contaminant transport parameters. The fitted contaminant transport parameters for the centrifuge test results were one to three orders of magnitude greater than the estimated parameters from the advection-dispersion equation. This indicates that the centrifuge model over estimated the contaminant transport phenomena. Thus, the centrifuge provides a non-conservative approach to modeling contaminant transport. It should be also noted that the advection-dispersion equation used in this study is a one layered model. Two layered modeling approaches are more appropriate for modeling this data since there are two layers with different partitioning coefficients. Further research is required to model the centrifuge test using two-layered advection-dispersion models.

Three Dimensional Dynamic Interaction of Foundations on Layered Half-Space (3차원 다층 반무한상 구조물의 동적 간섭에 관한 해석적 연구)

  • 조우연;이강원;임윤묵;김문겸
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.75-82
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    • 2001
  • A dynamic interaction analysis of an adjacent surface fecundation on a layered half-space is performed in the frequency domain. A semi-analytical approach is employed to reduce the integration range of the wavenumber in the surface fundamental solution for a layered half-space in boundary element (BE) formulations. The present study then adopts a combined boundary and finite element method to analyze the dynamic behavior of a system of flexible surface foundations on an elastic homogeneous and layered half-space. Numerical examples are presented to demonstrate the accuracy of the developed method. The examples show the feasibility of an extended application fur the complicated dynamic interaction of foundations on layered media.

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A Study on the Digital Implementation of Multi-layered Neural Networks for Pattern Recognition (패턴인식을 위한 다층 신경망의 디지털 구현에 관한 연구)

  • 박영석
    • Journal of the Institute of Convergence Signal Processing
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    • v.2 no.2
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    • pp.111-118
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    • 2001
  • In this paper, in order to implement the multi-layered perceptron neural network using pure digital logic circuit model, we propose the new logic neuron structure, the digital canonical multi-layered logic neural network structure, and the multi-stage multi-layered logic neural network structure for pattern recognition applications. And we show that the proposed approach provides an incremental additive learning algorithm, which is very simple and effective.

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