• Title, Summary, Keyword: wave computing

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Optimal Wave Source Position Determination Based on Wave Propagation Simulation (전자파 영향 평가를 통한 최적의 전파 기지국 위치 결정 방법)

  • 박성헌;박지헌
    • Korean Management Science Review
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    • v.18 no.1
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    • pp.41-54
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    • 2001
  • In this paper, we proposed a method to determine optimal wave source for mobile telephone communication. The approach is based on wave propagation simulation. Given a wave source we can determine wave propagation effects on every surfaces of wave simulation environment. The effect is evaluated as a cost function while the source’s position x, y, z work as variables for a parameter optimization. Wave propagated 3 dimensional space generates reflected waves whenever it hits boundary surface, it receives multiple waves which are reflected from various boundary surfacers in space. Three algorithms being implemented in this paper are based on a raytracing theory. If we get 3 dimensional geometry input as well as wave sources, we can compute wave propagation effects all over the boundary surfaces. In this paper, we present a new approach to compute wave propagation. First approach is tracing wave from a source. Source is modeled as a sphere casting vectors into various directions. This approach has limit in computing necessary wave propagation effects on all terrain surfaces. The second approach proposed is tracing wave backwards : tracing from a wave receiver to a wave source. For this approach we need to allocate a wave receiver on every terrain surfaces modeled, which requires enormous amount of computing time. But the second approach is useful for indoor wave propagation simulation. The last approach proposed in this paper is tracing sound by geometric computation. We allow direct, 1-relfe tion, and 2-reflection propagation. This approach allow us to save in computation time while achieving reasonable results. but due to the reflection limitaion, this approach works best in outdoor environment.

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Tree-dimensional FE Analysis of Acoustic Emission of Fiber Breakage using Explicit Time Integration Method (외연적 시간적분법을 이용한 복합재료 섬유 파단 시 음향방출의 3차원 유한요소 해석)

  • Paik, Seung-Hoon;Park, Si-Hyong;Kim, Seung-Jo
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.172-175
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    • 2005
  • The numerical simulation is performed for the acoustic emission and the wave propagation due to fiber breakage in single fiber composite plates by the finite element transient analysis. The acoustic emission and the following wave motions from a fiber breakage under a static loading is simulated to investigate the applicability of the explicit finite element method and the equivalent volume force model as a simulation tool of wave propagation and a modeling technique of an acoustic emission. For such a simple case of the damage event under static loading, various parameters affecting the wave motion are investigated for reliable simulations of the impact damage event. The high velocity and the small wave length of the acoustic emission require a refined analysis with dense distribution of the finite element and a small time step. In order to fulfill the requirement for capturing the exact wave propagation and to cover the 3-D simulation, we utilize the parallel FE transient analysis code and the parallel computing technology.

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An Accuracy Improvement in Solving Scalar Wave Equation by Finite Difference Method in Frequency Domain Using 49 Points Weighted Average Method (주파수영역에서 49점 가중평균을 이용한 scalar 파동방정식의 유한차분식 정확도 향상을 위한 연구)

  • Jang, Seong Hyung;Shin, Chang Soo;Yang, Dong Woo;Yang, Sung Jin
    • Economic and Environmental Geology
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    • v.29 no.2
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    • pp.183-192
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    • 1996
  • Much computing time and large computer memory are needed to solve the wave equation in a large complex subsurface layer using finite difference method. The time and memory can be reduced by decreasing the number of grid per minimun wave length. However, decrease of grid may cause numerical dispersion and poor accuracy. In this study, we present 49 points weighted average method which save the computing time and memory and improve the accuracy. This method applies a new weighted average to the coordinate determined by transforming the coordinate of conventional 5 points finite difference stars to $0^{\circ}$ and $45^{\circ}$, 25 points finite differenc stars to $0^{\circ}$, $26.56^{\circ}$, $45^{\circ}$, $63.44^{\circ}$ and 49 finite difference stars to $0^{\circ}$, $18.43^{\circ}$, $33.69^{\circ}$, $45^{\circ}$, $56.30^{\circ}$, $71.56^{\circ}$. By this method, the grid points per minimum wave length can be reduced to 2.5, the computing time to $(2.5/13)^3$, and the required core memory to $(2.5/13)^4$ computing with the conventional method.

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Analytical fragility curves of a structure subject to tsunami waves using smooth particle hydrodynamics

  • Sihombing, Fritz;Torbol, Marco
    • Smart Structures and Systems
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    • v.18 no.6
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    • pp.1145-1167
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    • 2016
  • This study presents a new method to computes analytical fragility curves of a structure subject to tsunami waves. The method uses dynamic analysis at each stage of the computation. First, the smooth particle hydrodynamics (SPH) model simulates the propagation of the tsunami waves from shallow water to their impact on the target structure. The advantage of SPH over mesh based methods is its capability to model wave surface interaction when large deformations are involved, such as the impact of water on a structure. Although SPH is computationally more expensive than mesh based method, nowadays the advent of parallel computing on general purpose graphic processing unit overcome this limitation. Then, the impact force is applied to a finite element model of the structure and its dynamic non-linear response is computed. When a data-set of tsunami waves is used analytical fragility curves can be computed. This study proves it is possible to obtain the response of a structure to a tsunami wave using state of the art dynamic models in every stage of the computation at an affordable cost.

Modular Cellular Neural Network Structure for Wave-Computing-Based Image Processing

  • Karami, Mojtaba;Safabakhsh, Reza;Rahmati, Mohammad
    • ETRI Journal
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    • v.35 no.2
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    • pp.207-217
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    • 2013
  • This paper introduces the modular cellular neural network (CNN), which is a new CNN structure constructed from nine one-layer modules with intercellular interactions between different modules. The new network is suitable for implementing many image processing operations. Inputting an image into the modules results in nine outputs. The topographic characteristic of the cell interactions allows the outputs to introduce new properties for image processing tasks. The stability of the system is proven and the performance is evaluated in several image processing applications. Experiment results on texture segmentation show the power of the proposed structure. The performance of the structure in a real edge detection application using the Berkeley dataset BSDS300 is also evaluated.

Submerged Porous Plate Wave Absorber

  • PARK W.T.;LEE S.H.;KEE S.T.
    • Journal of Ocean Engineering and Technology
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    • v.19 no.4
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    • pp.9-14
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    • 2005
  • In the present paper, the wave absorbing performance of the fully submerged horizontal porous plates has been investigated, numerically and experimentally. The submerged porous system is composed of multi-layered horizontal porous plates that are clamped at the vertical setwall, which are slightly inclined and placed vertically, in parallel, with spacing. The hydrodynamic interaction of incident waves with the rigid porous multi-layered plates was formulated within the context of linear wave-body interaction theory and Darcy's law. In order to validate the effectiveness of the present computing code, the numerical results were compared with the analytical and experimental results. It is found that triple horizontal porous plates with slight inclination, if properly tuned for wave energy dissipation against the standing waves in front of the vertical wall, can have high performances in reducing the reflected wave amplitudes against the incident waves over a wide range of wave frequency.

Computation of the inviscid drift force caused by nonlinear waves on a submerged circular cylinder

  • Koh, Hyeok-Jun;Cho, Il-Hyoung
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.3 no.3
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    • pp.201-207
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    • 2011
  • In this paper, we focused on computing the higher-harmonic components of the transmitted wave passing over a submerged circular cylinder to show that it is causing a horizontal negative drift force. As numerical models, a circular cylinder held fixed under free surface in deep water is adopted. As the submergence of a circular cylinder decreases and the incident wavelength becomes longer, the higher-harmonic components of the transmitted wave starts to increase. An increase of the higher-harmonic components of the transmitted wave makes the horizontal drift force be negative. It is also found that the higher-harmonic amplitudes averaged over the transmitted wave region become larger with the increase of wave steepness and wavelength as well as the decrease of submergence depth.

Development of GPU-accelerated kinematic wave model using CUDA fortran (CUDA fortran을 이용한 GPU 가속 운동파모형 개발)

  • Kim, Boram;Park, Seonryang;Kim, Dae-Hong
    • Journal of Korea Water Resources Association
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    • v.52 no.11
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    • pp.887-894
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    • 2019
  • We proposed a GPU (Grapic Processing Unit) accelerated kinematic wave model for rainfall runoff simulation and tested the accuracy and speed up performance of the proposed model. The governing equations are the kinematic wave equation for surface flow and the Green-Ampt model for infiltration. The kinematic wave equations were discretized using a finite volume method and CUDA fortran was used to implement the rainfall runoff model. Several numerical tests were conducted. The computed results of the GPU accelerated kinematic wave model were compared with several measured and other numerical results and reasonable agreements were observed from the comparisons. The speed up performance of the GPU accelerated model increased as the number of grids increased, achieving a maximum speed up of approximately 450 times compared to a CPU (Central Processing Unit) version, at least for the tested computing resources.

A Study on Mount Performance for Structure-Borne Noise Reduction in Resiliently Mounted System (탄성지지된 시스템의 마운트 고체음저감 성능에 관한 연구)

  • Kim, Hyun-Sil;Kim, Jae-Seung;Kim, Bong-Ki
    • The Journal of the Acoustical Society of Korea
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    • v.26 no.2E
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    • pp.50-55
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    • 2007
  • SBN (Structure-Borne Noise) reduction in resiliently mounted machineries are predicted by using mass-spring model and wave model. In mass-spring model, mount is modeled as a spring, while in wave model, mount is considered as an equivalent elastic rod for taking account into longitudinal wave propagation. The predictions for SBN reduction through mounts are compared to the measurements for four different pumps. It is found that the mass-spring model is valid only in low frequency range below few hundred Hz, while for high frequency ranges longitudinal wave propagation in the mount must be considered to explain the measurements. It is also shown that impedance of the floor slightly affects low frequency behaviour in mass-spring and wave model below 50 Hz - 80 Hz, so that in engineering practice the effect of floor impedance may be neglected in computing mount performance.

Hybrid parallel smooth particle hydrodynamic for probabilistic tsunami risk assessment and inland inundation

  • Sihombing, Fritz;Torbol, Marco
    • Smart Structures and Systems
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    • v.23 no.2
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    • pp.185-194
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    • 2019
  • The probabilistic tsunami risk assessment of large coastal areas is challenging because the inland propagation of a tsunami wave requires an accurate numerical model that takes into account the interaction between the ground, the infrastructures, and the wave itself. Classic mesh-based methods face many challenges in the propagation of a tsunami wave inland due to their ever-moving boundary conditions. In alternative, mesh-less based methods can be used, but they require too much computational power in the far-field. This study proposes a hybrid approach. A mesh-based method propagates the tsunami wave from the far-field to the near-field, where the influence of the sea floor is negligible, and a mesh-less based method, smooth particle hydrodynamic, propagates the wave onto the coast and inland, and takes into account the wave structure interaction. Nowadays, this can be done because the advent of general purpose GPUs made mesh-less methods computationally affordable. The method is used to simulate the inland propagation of the 2004 Indian Ocean tsunami off the coast of Indonesia.