• Title/Summary/Keyword: free motion

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Analytical nonlocal elasticity solution and ANN approximate for free vibration response of layered carbon nanotube reinforced composite beams

  • Emrah Madenci;Saban Gulcu;Kada Draiche
    • Advances in nano research
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    • v.16 no.3
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    • pp.251-263
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    • 2024
  • This article investigates the free vibration behavior of carbon nanotube reinforced composite (CNTRC) beams embedded using variational analytical methods and artificial neural networks (ANN). The material properties of layered functionally graded CNTRC (FG-CNTRC) beams are estimated using nonlocal parameters modified power-law with different types of CNT distributions through the thickness direction of the beam. Adopting Eringen's nonlocal elasticity theory to capture the small size effects, the nonlocal governing equations are derived and solved using the analytical method. And also, the problem was analyzed using the ANN method. The architecture of the proposed ANN model is 3-9-1. In the experiments, we used 112 different data to predict the natural frequency using ANN. Based on the nonlocal differential constitutive relations of Eringen, the equations of motion as well as the boundary conditions of the beam are derived using Hamilton's principle. The classical beam theory is used to formulate a governing equation for predicting the free vibration of laminated CNTRC beams. According to the experimental results, the prediction ability of the ANN model is very good and the natural frequency can be predicted in ANN without attempting any experiments.

Using 3D theory of elasticity for free vibration analysis of functionally graded laminated nanocomposite shells

  • R. Bina;M. Soltani Tehrani;A. Ahmadi;A. Ghanim Taki;R. Akbarian
    • Steel and Composite Structures
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    • v.52 no.4
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    • pp.487-499
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    • 2024
  • The primary objective of this study is to analyze the free vibration behavior of a sandwich cylindrical shell with a defective core and wavy carbon nanotube (CNT)-enhanced face sheets, utilizing the three-dimensional theory of elasticity. The intricate equations of motion for the structure are solved semi-analytically using the generalized differential quadrature method. The shell structure consists of a damaged isotropic core and two external face sheets. The distributions of CNTs are either functionally graded (FG) or uniform across the thickness, with their mechanical properties determined through an extended rule of mixture. In this research, the conventional theory regarding the mechanical effectiveness of a matrix embedding finite-length fibers has been enhanced by introducing tube-to-tube random contact. This enhancement explicitly addresses the progressive reduction in the tubes' effective aspect ratio as the filler content increases. The study investigates the influence of a damaged matrix, CNT distribution, volume fraction, aspect ratio, and waviness on the free vibration characteristics of the sandwich cylindrical shell with wavy CNT-reinforced face sheets. Unlike two-dimensional theories such as classical and the first shear deformation plate theories, this inquiry is grounded in the three-dimensional theory of elasticity, which comprehensively accounts for transverse normal deformations.

Quantitative Comparison of Motion Artifacts in PET Images using Data-Based Gating (데이터 기반 게이팅을 이용한 PET 영상의 움직임 인공물의 정량적 비교)

  • Jin Young, Kim;Gye Hwan, Jin
    • Journal of the Korean Society of Radiology
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    • v.17 no.1
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    • pp.91-98
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    • 2023
  • PET is used effectively for biochemical or pathological phenomena, disease diagnosis, prognosis determination after treatment, and treatment planning because it can quantify physiological indicators in the human body by imaging the distribution of various biochemical substances. However, since respiratory motion artifacts may occur due to the movement of the diaphragm due to breathing, we would like to evaluate the practical effect by using the a device-less data-driven gated (DDG) technique called MotionFree with the phase-based gating correction method called Q.static scan mode. In this study, images of changes in moving distance (0 cm, 1 cm, 2 cm, 3 cm) are acquired using a breathing-simulated moving phantom. The diameters of the six spheres in the phantom are 10 mm, 13 mm, 17 mm, 22 mm, 28 mm, and 37 mm, respectively. According to maximum standardized uptake value (SUVmax) measurements, when DDG was applied based on the moving distance, the average SUVmax of the correction effect by the moving distance was improved by 1.92, 2.48, 3.23 and 3.00, respectively. When DDG was applied based on the diameter of the phantom spheres, the average SUVmax of the correction effect by the moving distance was improved by 2.37, 2.02, 1.44, 1.20, 0.42 and 0.52 respectively.

Deadlock-free Routing of an AGV in Accelerated Motion (가감속을 고려한 교착없는 AGV 주행경로설정)

  • Choe, Ri;Park, Tae-Jin;Ryu, Kwang-Ryel
    • Journal of Navigation and Port Research
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    • v.30 no.10 s.116
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    • pp.855-860
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    • 2006
  • In the environment where multiple AGVs(Automated Guided Vehicles) operate concurrently in limited space, collisions, deadlocks, and livelocks which have negative effect on the productivity of AGVs occure more frequently. The accelerated motion of an AGV is also one of the factors that make the AGV routing more difficult because the accelerated motion makes it difficult to estimate the vehicle's exact travel time. In this study, we propose methods of avoiding collisions, deadlocks, and livelocks using OAR(Occupancy Area Reservation) table, and selecting best route by estimating the travel time of an AGV in accelerated motion. A set of time-driven simulation works validated the effectiveness of the proposed methods.

Evaluation of the Effect of Input Motions on Earthquake-Induced Settlement of Embankment Dams (입력지진파에 따른 지진 시 필댐의 침하량 영향관계 분석)

  • Jo, Seong-Bae;Kim, Nam-Ryong;Kim, Tae Min
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.40 no.5
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    • pp.509-520
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    • 2020
  • Currently, the criteria for input motions used in dam seismic design are clearly presented in general provisions of seismic design (KDS 17 10 00), and seismic ground motion records should be matched to the standard design response spectrum. However, the effect on the results is not assessed according to the selection of the seismic ground motion records, making it difficult to select seismic input motions. Therefore, in this study, the change in the amount of crest settlement of an embankment dam was assessed through numerical analysis after matching the seismic ground motion records of domestic and overseas earthquakes in accordance with the standard design response spectrum provided in the seismic design code (KDS 17 10 00). The results showed that the behavior of the upper part of the embankment, such as maximum acceleration at the crest and amplification through the dam, rather than the effect of free-field acceleration, had a greater effect on the amount of crest settlement. Moreover, it was confirmed that even an input seismic motion matched to the standard design response spectrum can make a difference in settlement depending on the characteristics of amplification through a dam body.

Application of Vector Scalar Product to Solve the Kinematic Equations in the Earth's Gravitational Field (지구 중력장 내에서 성립하는 운동 상태 방정식의 해를 구하기 위한 벡터의 스칼라 프로덕트 응용)

  • Um, Kee-Hong
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.17 no.6
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    • pp.217-222
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    • 2017
  • Any object located in the earth's gravitational field experiences a force in the direction of the center of the earth. In order to describe the motion of objects in the field, the solutions to a system of simultaneous vector kinematic equations need to be obtained. In the analysis of freely-falling objects, the reference direction +y is usually defined to be the downward direction. In the analysis of the motion of objects thrown upward, the reference direction +y is usually defined to be the upward direction. In the analysis of the motion of objects thrown downward, the reference direction +y is usually defined to be the downward direction. In this paper, we show that the choice of reference axis in either upward or direction gives the same results by adopting a scalar product of two vectors in solving the vector kinematic equations. It is rare to find other examples of using a scalar product of two vectors in solving vector kinematic equations describing the motion of objects. An application of this study is that we can arbitrarily choose the reference direction for objects moving in a horizontal direction, including projectile motions.

Development of Basic Education Models of Stop-Motion Techniques (스톱모션 기법의 기초 교육모형 개발)

  • Yang, Se-Hyeok
    • The Journal of the Korea Contents Association
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    • v.7 no.11
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    • pp.258-269
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    • 2007
  • Stop-motion is a technique that should be in the basic stage of the animation education, as it gives a chance for students to learn a three-dimensional sense about the movement, just to name a few, as this technique can give movements to actual objects in real life. As the old animation education is consist of forms to make a short animation. most students got a situation that they should be reeducated about 'movement' at their work after graduation from the school. It is necessary to have a systematic education about basic movement for 16 weeks to solve the problem under these circumstances. Therefore this researcher came to seek a more effective way for students who aim to major in stop-motion as well as students who try to nurture their basic capability of animation. This study aimed to present the optimized education model for the basic stage of the stop-motion technique specifically around expressions such as 'walking/ free-movement/ facial expression'.

Numerical simulation of wave interacting with a free rolling body

  • Jung, Jae Hwan;Yoon, Hyun Sik;Chun, Ho Hwan;Lee, Inwon;Park, Hyun
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.5 no.3
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    • pp.333-347
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    • 2013
  • The present study numerically models the interaction between a regular wave and the roll motion of a rectangular floating structure. In order to simulate two-dimensional incompressible viscous two-phase flow in a numerical wave tank with the rectangular floating structure, the present study used the volume of fluid method based on the finite volume method. The sliding mesh technique is adopted to handle the motion of the rectangular floating structure induced by fluid-structure interaction. The effect of the wave period on the flow, roll motion and forces acting on the structure is examined by considering three different wave periods. The time variations of the wave height and the roll motion of the rectangular structure are in good agreement with experimental results for all wave periods. The present response amplitude operator is in good agreement with experimental results with the linear potential theory. The present numerical results effectively represent the entire process of vortex generation and evolution described by the experimental results. The longer wave period showed a different mechanism of the vortex evolution near each bottom corner of the structure compared to cases of shorter wave periods. In addition, the x-directional and z-directional forces acting on the structure are analyzed.

Injection of an Intermediate Fluid into a Rotating Cylindrical Container Filled with Two-layered Fluid

  • Na, Jung-Yul;Hwang, Byong-Jun
    • Journal of the korean society of oceanography
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    • v.31 no.4
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    • pp.173-182
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    • 1996
  • A median-density fluid was injected into the upper layer of a two-layered fluid in a rotating cylindrical container. Several sets of the top and bottom boundary configurations were employed and the flow pattern of each layer including the injected fluid was observed to determine the factors that affect the path of the injected intermediate fluid. The axisymmetric path of the intermediate fluid when the upper layer had a free surface, changed into the asymmetric path with bulged-shape radial spreading whenever either the upper layer or the lower layer had ${\beta}$-effect. The internal Fronds number that controls the shape of the interface turned out to be the most important parameter that determines the radial spreading in terms of location and strength. When the upper and lower layer had the ${\beta}$-effect, convective overturning produced anticyclonic vortices at the frontal edge of the intermediate fluid, and that could enhance the vertical mixing of different density fluids. The intermediate fluid did not produce any topographic effect on the upper-layer motion during its spreading over the interface, since its thickness was very small. However, its anticyclonic motion within the bulged-shape produced a cyclonic motion in the lower layer just beneath the bulge.

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Planar Motion Mechanism Test of the Mobile Harbor Running in Design Speed in Circulating Water Channel

  • Yoon, Hyeon-Kyu;Kang, Joo-Nyun
    • Journal of Navigation and Port Research
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    • v.34 no.7
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    • pp.525-532
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    • 2010
  • Mobile Harbor (MH) is a new transportation platform that can load and unload containers onto and from very large container ships at sea. It could navigate near harbors where several vessels run, or it could navigate through very narrow channels. In the conceptual design phase when the candidate design changes frequently according to the various performance requirements, it is very expensive and time-consuming to carry out model tests using a large model in a large towing tank and a free-running model test in a large maneuvering basin. In this paper, a new Planar Motion Mechanism(PMM) test in a Circulating Water Channel (CWC) was conducted in order to determine the hydrodynamic coefficients of the MH. To do this, PMM devices including three-component load cells and inertia tare device were designed and manufactured, and various tests of the MH such as static drift test, pure sway test, pure yaw test, and drift-and-yaw combined test were carried out. Using those coefficients, course-keeping stability was analyzed. In addition, the PMM tests results carried out for the same KCS (KRISO container ship) were compared with our results in order to confirm the test validity.