• Title/Summary/Keyword: effective-medium theory

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Vibration and stability of embedded cylindrical shell conveying fluid mixed by nanoparticles subjected to harmonic temperature distribution

  • Shokravi, Maryam;Jalili, Nader
    • Wind and Structures
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    • v.25 no.4
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    • pp.381-395
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    • 2017
  • Nonlinear vibration and instability of cylindrical shell conveying fluid-nanoparticles mixture flow are studied in this article. The surrounding elastic medium is modeled by Pasternak foundation. Mixture rule is used for obtaining the effective viscosity and density of the fluid-nanoparticles mixture flow. The material properties of the elastic medium and cylindrical shell are assumed temperature-dependent. Employing first order shear deformation theory (FSDT), the motion equations are derived using energy method and Hamilton's principal. Differential quadrature method (DQM) is used for obtaining the frequency and critical fluid velocity. The effects of different parameters such as volume percent of nanoparticles, boundary conditions, geometrical parameters of cylindrical shell, temperature change, elastic foundation and fluid velocity are shown on the frequency and critical fluid velocity of the structure. Results show that with increasing volume percent of nanoparticles in the fluid, the frequency and critical fluid velocity will be increases.

Vibration response of smart concrete plate based on numerical methods

  • Taherifar, Reza;Chinaei, Farhad;Faramoushjan, Shahram Ghaedi;Esfahani, Mohammad Hossein Nasr;Esfahani, Shabnam Nasr;Mahmoudi, Maryam
    • Smart Structures and Systems
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    • v.23 no.4
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    • pp.387-392
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    • 2019
  • This research deals with the vibration analysis of embedded smart concrete plate reinforced by zinc oxide (ZnO). The effective material properties of structure are considered based on mixture rule. The elastic medium is simulated by orthotropic visco-Pasternak medium. The motion equations are derived applying Sinusoidal shear deformation theory (SSDT). The differential quadrature (DQ) method is applied for calculating frequency of structure. The effects of different parameters such as volume percent of ZnO, boundary conditions and geometrical parameters on the frequency of system are shown. The results are compared with other published works in the literature. Results indicate that the ZnO have an important role in frequency of structure.

Development of an Effective Manufacturing Scheduling System for PCB Manufacturing Line Using Dual DBR Method (복수 DBR 기법을 이용한 PCB 생산라인의 효율적인 생산계획 시스템 개발)

  • Yoshida, Atsunori;Park, Jeong-Hyeon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.10 no.10
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    • pp.2935-2944
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    • 2009
  • This paper proposes Dual DBR(Drum-Buffer-Rope) system for a small-to-medium-sized PCB(Printed Circuit Board) manufacturing line. DBR method of TOC(Theory of Constraints) is an effective system for a small-to-medium-sized company to build production scheduling system. But to apply it to PCB line, it needs more technical consideration because of multiple constraints, looping process line and complex buffer management. This paper proposes an answer of these problems using Dual DBR to build production scheduling system more successfully. And it was confirmed that lead time was reduced more than 20% applying Dual DBR system to a domestic PCB manufacturing line actually.

Algorithm of solving the problem of small elastoplastic deformation of fiber composites by FEM

  • Polatov, Askhad M.;Khaldjigitov, Abduvali A.;Ikramov, Akhmat M.
    • Advances in Computational Design
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    • v.5 no.3
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    • pp.305-321
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    • 2020
  • In this paper is presented the solution method for three-dimensional problem of transversely isotropic body's elastoplastic deformation by the finite element method (FEM). The process of problem solution consists of: determining the effective parameters of a transversely isotropic medium; construction of the finite element mesh of the body configuration, including the determination of the local minimum value of the tape width of non-zero coefficients of equation systems by using of front method; constructing of the stiffness matrix coefficients and load vector node components of the equation for an individual finite element's state according to the theory of small elastoplastic deformations for a transversely isotropic medium; the formation of a resolving symmetric-tape system of equations by summing of all state equations coefficients summing of all finite elements; solution of the system of symmetric-tape equations systems by means of the square root method; calculation of the body's elastoplastic stress-strain state by performing the iterative process of the initial stress method. For each problem solution stage, effective computational algorithms have been developed that reduce computational operations number by modifying existing solution methods and taking into account the matrix coefficients structure. As an example it is given, the problem solution of fibrous composite straining in the form of a rectangle with a system of circular holes.

Buckling analysis of concrete plates reinforced by piezoelectric nanoparticles

  • Taherifar, Reza;Mahmoudi, Maryam;Nasr Esfahani, Mohammad Hossein;Khuzani, Neda Ashrafi;Esfahani, Shabnam Nasr;Chinaei, Farhad
    • Computers and Concrete
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    • v.23 no.4
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    • pp.295-301
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    • 2019
  • In this paper, buckling analyses of composite concrete plate reinforced by piezoelectric nanoparticles is studied. The Halphin-Tsai model is used for obtaining the effective material properties of nano composite concrete plate. The nano composite concrete plate is modeled by Third order shear deformation theory (TSDT). The elastic medium is simulated by Winkler model. Employing nonlinear strains-displacements, stress-strain, the energy equations of concrete plate are obtained and using Hamilton's principal, the governing equations are derived. The governing equations are solved based on Navier method. The effect of piezoelectric nanoparticles volume percent, geometrical parameters of concrete plate and elastic foundation on the buckling load are investigated. Results showed that with increasing Piezoelectric nanoparticles volume percent, the buckling load increases.

Buckling analysis of plates reinforced by Graphene platelet based on Halpin-Tsai and Reddy theories

  • Javani, Rasool;Bidgoli, Mahmood Rabani;Kolahchi, Reza
    • Steel and Composite Structures
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    • v.31 no.4
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    • pp.419-426
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    • 2019
  • In this paper, buckling analyses of composite plate reinforced by Graphen platelate (GPL) is studied. The Halphin-Tsai model is used for obtaining the effective material properties of nano composite plate. The nano composite plate is modeled by Third order shear deformation theory (TSDT). The elastic medium is simulated by Winkler model. Employing nonlinear strains-displacements, stress-strain, the energy equations of plate are obtained and using Hamilton's principal, the governing equations are derived. The governing equations are solved based on Navier method. The effect of GPL volume percent, geometrical parameters of plate and elastic foundation on the buckling load are investigated. Results showed that with increasing GPLs volume percent, the buckling load increases.

Study of Toxicity Presence Classification about Herbal Diet in Tang-aec-pyeon of Dong-ui-bo-gam (동의보감 탕액편에 기재된 식이본초의 독성유무에 대한 분류 연구)

  • Shin, Ho-Dong;Jeong, Jong-Un
    • The Journal of Korean Medicine
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    • v.32 no.1
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    • pp.12-35
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    • 2011
  • Objectives: The two criteria to clarify the toxicity of a herbal diet are well known. Although mechanical analysis of effective ingredients, a western approach, is widely used, the toxicity presence classification through the herbal analysis from a viewpoint of a theory of the herbal medicine properties has been disregarded. This study is for the safe use of a herbal diet through classification and study of toxicity presence in the herbal diet from the view of a theory of herbal medicine properties, one of the methods of Oriental Medicine. Methods: We classified and studied the toxicity presence in four kinds of herbal diets, waters and grains, animals groups, fruits and vegetables, and herbs and trees, excluding mineral natural drugs, of 1,400 kinds of medicines in 16 chapters of Tang-aec-pyeon, Dong-ui-bo-gam, for which the herbal analysis from a viewpoint of the theory of the herbal medicine properties has been used. The criteria of the toxicity presence in the herbal diet have been largely classified into the toxicant and the non-toxicant, and the toxicant is in turn classified into the insignificant, the medium and the significant. The category to clarify herbal diet has been limited to simultaneous utilization of food and natural drugs. The main text is Dong-ui-bo-gam, although diverse other references have also been used. Results: There are toxicant diets: a kind of tortoise meat of animals groups; five kinds of grains part in fruits and vegetables: aengdo, peach, oyat, small apple and gingko nut; and 12 kinds of vegetables part in fruits and vegetables: ginger, oriental cabbage, lettuce, chongbaek, onion, garlic, leek, fern, houttuynia cordata (myeol), pyeongji, geundae, and spinach, which should be prohibited from long-term use both as food and medicine. Conclusion: If herbal diet is used as health food supplements or food, the toxicity presence should be considered on the grounds of an Oriental Medicine theory of the herbal medicine properties.

Ashbery's Aesthetics of Difficulty: Information Theory and Hypertext

  • Ryoo, Gi Taek
    • Journal of English Language & Literature
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    • v.58 no.6
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    • pp.1001-1021
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    • 2012
  • This paper is concerned with John Ashbery's poetics of difficulty, questioning in particular the nature of communication in his difficult poems. Ashbery has an idea of poetry as 'information' to be transmitted to the reader. Meaning, however, is to be created by a series of selections among equally probable choices. Ashbery's poetry has been characterized by resistance to the interpretive system of meaning. But the resistance itself, as I will argue, can be an effective medium of communication as the communicated message is not simply transmitted but 'selected' and thus created by the reader. In Ashbery's poetry, disruptive 'noise' elements can be processed as constructive information. What is normally considered a hindrance or noise can be reversed and added to the information. In Ashbery's poems, random ambiguities or noises can be effectively integrated into the final structure of meaning. Such a stochastic sense of information transfer has been embodied in Ashbery's idea of creating a network of verbal elements in his poetry, analogous to the interconnecting web of hypertext, the most dynamic medium 'information technology' has brought to us. John Ashbery, whose poems are simultaneously incomprehensible and intelligent, employs ambiguities or noise in his poetry, with an attempt to reach through linear language to express nonlinear realities. It is therefore my intention to examine Ashbery's poetics of difficulty, from a perspective of communication transmission, using the theories of information technology and the principles of hypertext theory. Ashbery's poetry raises precisely the problem confronted in the era of communication and information technology. The paper will also show how his aesthetics of difficulty reflects the culture of our uncertain times with overflowing information. With his difficult enigmatic poems, Ashbery was able to move ahead of the technological advances of his time to propose a new way of perceiving the world and life.

Velocity-effective stress response of $CO_2$-saturated sandstones ($CO_2$로 포화된 사암의 속도-유효응력 반응)

  • Siggins, Anthony F.
    • Geophysics and Geophysical Exploration
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    • v.9 no.1
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    • pp.60-66
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    • 2006
  • Three differing sandstones, two synthetic and one field sample, have been tested ultrasonically under a range of confining pressures and pore pressures representative of in-situ reservoir pressures. These sandstones include: a synthetic sandstone with calcite intergranular cement produced using the CSIRO Calcite In-situ Precipitation Process (CIPS); a synthetic sandstone with silica intergranular cement; and a core sample from the Otway Basin Waarre Formation, Boggy Creek 1 well, from the target lithology for a trial $CO_2$ pilot project. Initial testing was carried on the cores at "room-dried" conditions, with confining pressures up to 65 MPa in steps of 5 MPa. All cores were then flooded with $CO_2$, initially in the gas phase at 6 MPa, $22^{\circ}C$, then with liquid-phase $CO_2$ at a temperature of $22^{\circ}C$ and pressures from 7 MPa to 17 MPa in steps of 5 MPa. Confining pressures varied from 10 MPa to 65 MPa. Ultrasonic waveforms for both P- and S-waves were recorded at each effective pressure increment. Velocity versus effective pressure responses were calculated from the experimental data for both P- and S-waves. Attenuations $(1/Q_p)$ were calculated from the waveform data using spectral ratio methods. Theoretical calculations of velocity as a function of effective pressure for each sandstone were made using the $CO_2$ pressure-density and $CO_2$ bulk modulus-pressure phase diagrams and Gassmann effective medium theory. Flooding the cores with gaseous phase $CO_2$ produced negligible change in velocity-effective stress relationships compared to the dry state (air saturated). Flooding with liquid-phase $CO_2$ at various pore pressures lowered velocities by approximately 8% on average compared to the air-saturated state. Attenuations increased with liquid-phase $CO_2$ flooding compared to the air-saturated case. Experimental data agreed with the Gassmann calculations at high effective pressures. The "critical" effective pressure, at which agreement with theory occurred, varied with sandstone type. Discrepancies are thought to be due to differing micro-crack populations in the microstructure of each sandstone type. The agreement with theory at high effective pressures is significant and gives some confidence in predicting seismic behaviour under field conditions when $CO_2$ is injected.

Vibration analysis thermally affected viscoelastic nanosensors subjected to linear varying loads

  • Ebrahimi, Farzad;Babaei, Ramin;Shaghaghi, Gholam Reza
    • Advances in nano research
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    • v.6 no.4
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    • pp.399-422
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    • 2018
  • Unwanted vibration is an issue in many industrial systems, especially in nano-devices. There are many ways to compensate these unwanted vibrations based on the results of the past researches. Elastic medium and smart material etc. are effective methods to restrain unnecessary vibration. In this manuscript, dynamic analysis of viscoelastic nanosensor which is made of functionally graded (FGM) nanobeams is investigated. It is assumed that, the shaft is flexible. The system is modeled based on Timoshenko beam theory and also environmental condition, external linear varying loads and thermal loading effect are considered. The equations of motion are extracted by using energy method and Hamilton principle to describe the translational and shear deformation's behavior of the system. Governing equations of motion are extracted by supplementing Eringen's nonlocal theory. Finally vibration behavior of system especially the frequency of system is developed by implementation Semi-analytical differential transformed method (DTM). The results are validated in the researches that have been done in the past and shows good agreement with them.