• 제목/요약/키워드: numerical comparison problems

검색결과 221건 처리시간 0.027초

Solving Dynamic Equation Using Combination of Both Trigonometric and Hyperbolic Cosine Functions for Approximating Acceleration

  • Quoc Do Kien;Phuoc Nguyen Trong
    • Journal of Mechanical Science and Technology
    • /
    • 제19권spc1호
    • /
    • pp.481-486
    • /
    • 2005
  • This paper introduces a numerical method for integration of the linear and nonlinear differential dynamic equation of motion. The variation of acceleration in two time steps is approximated as a combination of both trigonometric cosine and hyperbolic cosine functions with weighted coefficient. From which all necessary formulae are elaborated for the direct integration of the governing equation. A number of linear and nonlinear dynamic problems with various degrees of freedom are analysed using both the suggested method and Newmark method for the comparison. The numerical results show high advantages and effectiveness of the new method.

수치해석 및 실험에 의한 LCD-TV의 열분포 분석 (Analysis of Thermal Distribution for LCD-TV Using Numerical Simulation and Experiment)

  • 김윤석;이정권;정두환;고한서
    • 대한기계학회:학술대회논문집
    • /
    • 대한기계학회 2003년도 추계학술대회
    • /
    • pp.302-307
    • /
    • 2003
  • Demand of the LCD-TV is remarkably increasing with development of the LCD technology in these days. Thus, this research has analyzed thermal problems such as heat transfer characteristics inside and outside the LCD-TV using numerical simulation and experiments. The simulated results have been compared with the experimental results using an infrared (IR) camera and T-type thermocouples. The optimal design of structure has been proposed to improve the thermal efficiency of radiation from the comparison.

  • PDF

MODEL FOR THE CONTAMINATION OF CONFINED AQUIFERS BY POLLUTANTS

  • Bestman, A.R.;Odigi, M.I.
    • 한국수학교육학회지시리즈B:순수및응용수학
    • /
    • 제6권2호
    • /
    • pp.113-120
    • /
    • 1999
  • This paper studies the problem of an infinite confined aquifer which at time t < 0 is assumed motionless. At time t = 0 crude oil seeps into the aquifer, thereby contaminating the valuable drinking water. Since the crude oil and water are im-miscible, the problem is posed as a one-dimensional two-phase unsteady moving boundary problem. A similarity solution is developed in which the moving front parameter is obtained by Newton-Ralphson iteration. A numerical scheme, involving the front tracking method, is devised employing the fourth order Runge-Kutta method. Comparison of the exact and numerical schemes shows an error of only 3%. Thus the developed numerical scheme is quite accurate in tackling more realistic problems where exact solutions are not possible.

  • PDF

Using artificial intelligence to solve a smart structure problem

  • Kaiwen, Liu;Jun, Gao;Ruizhe, Qiu
    • Structural Engineering and Mechanics
    • /
    • 제85권3호
    • /
    • pp.393-406
    • /
    • 2023
  • Smart structures are those structure that could adopt some behavior to prevent instability in their responses. The recognition of stability deterioration has been performed through rigid mathematical formulations in control theory and unpredicted results could not be addressed in control systems since they are able to only work under their predefined condition. On the other hand, incorporating all affecting parameters could result in high computational cost and delay time in the response of the systems. Artificial intelligence (AI) method has shown to be a promising methodology not only in the computer science by at everyday life and in engineering problems. In the present study, we exploit the capabilities of artificial intelligence method to obtain frequency response of a smart structure. In this regard, a comprehensive development of equations is presented using Hamilton' principle and first order shear deformation theory. The equations were solved by numerical methods and the results are used to train an artificial neural network (ANN). It is demonstrated that ANN modeling could provide accurate results in comparison to the numerical solutions and it take less time than numerical solution.

해안지하수개발 최적화수치모델과 해석해의 비교연구 (Comparison of a Groundwater Simulation-Optimization Numerical Model with the Analytical Solutions)

  • 시뢰;최뢰;이찬종;박남식
    • 한국수자원학회:학술대회논문집
    • /
    • 한국수자원학회 2009년도 학술발표회 초록집
    • /
    • pp.905-908
    • /
    • 2009
  • In the management of groundwater in coastal areas, saltwater intrusion associated with extensive groundwater pumping, is an important problem. The groundwater optimization model is an advanced method to study the aquifer and decide the optimal pumping rates or optimal well locations. Cheng and Park gave the analytical solutions to the optimization problems basing on Strack's analytical solution. However, the analytical solutions have some limitations of the property of aquifer, boundary conditions, and so on. A simulation-optimization numerical method presented in this study can deal with non-homogenous aquifers and various complex boundary conditions. This simulation-optimization model includes the sharp interface solution which solves the same governing equation with Strack's analytical solution, therefore, the freshwater head and saltwater thickness should be in the same conditions, that can lead to the comparable results in optimal pumping rates and optimal well locations for both of the solutions. It is noticed that the analytical solutions can only be applied on the infinite domain aquifer, while it is impossible to get a numerical model with infinite domain. To compare the numerical model with the analytical solutions, calculation of the equivalent boundary flux was planted into the numerical model so that the numerical model can have the same conditions in steady state with analytical solutions.

  • PDF

평면 프리즘 LED 조명기구 배광수치모델의 다양한 배광 제어를 위한 연구 (A Study for the Control of Various Luminous Intensity Distribution in Numerical Model of Planar Prism LED Luminaire)

  • 김유신;최안섭
    • 조명전기설비학회논문지
    • /
    • 제25권12호
    • /
    • pp.60-66
    • /
    • 2011
  • There are several technological problems have to be resolved for LEDs to be used as a general purpose light source. In addition, there are several differences between existing luminaires and the general planer LED luminaire for the intensity distribution. Therefore, the optical engineer then faces the challenging a problem of designing for a spatially extended and non-uniform light source. In the previous studies on the optical design of luminaires, a lot of studies on reflectors and light source have been conducted but the ones on prisms and lenses are insufficient at present. This study developed the numerical model of planar prism LED luminaire to control luminous intensity distribution of LED luminaires. And this study presents an optical calculation process for the prism optical design of a planar prism LED luminaire and a comparison of the simulation results between the developed numerical model and Photopia 2.0 to verify the accuracy of the numerical model. In addition, this study showed a method for the control of various luminous intensity distribution from the developed numerical model.

사각형 판 유한 요소들의 정적 성능 비교 분석 I (Comparative Study on the Performance of Quadrilateral Plate Elements for the static Analysis of Limear Elastic structures( I );Displacements)

  • 이병채;이용주
    • 전산구조공학
    • /
    • 제3권4호
    • /
    • pp.91-104
    • /
    • 1990
  • 사각형 판 유한요소의 정적 성능을 여러 가지 문제에 대한 수치 실험을 통해 비교 분석하였다. Kirchhoff이론과 Mindlin이론에 근거한 변위요소, 평형요소, Mixed 또는 Hybrid요소들을 대상으로 문헌조사를 통해 우수요소를 선정하였으며 사각형 판 문제, 마름모형 판 문제, 원형 판 문제, 외팔보형 판 문제를 다양한 격자, 경계조건에 대해 풀어 해를 비교하였다. Kirchhoff요소에서는 12자유도요소로 Armanios의 요소, 24 자유도 요소로 Watkins요소의 거동이 우수하였으나 전반적으로 Mindlin요소에 비해 거동이 떨어진다. Mindlin요소 중에서는 Hinton의 요소가 효율성, 수렴성, 신뢰성의 면에서 가장 우수하나 마름모형 판 문제나 뒤틀린 격자 문제등에서는 거동이 좋지 않으므로 계속 연구할 필요가 있다.

  • PDF

Gas-liquid interface treatment in underwater explosion problem using moving least squares-smoothed particle hydrodynamics

  • Hashimoto, Gaku;Noguchi, Hirohisa
    • Interaction and multiscale mechanics
    • /
    • 제1권2호
    • /
    • pp.251-278
    • /
    • 2008
  • In this study, we investigate the discontinuous-derivative treatment at the gas-liquid interface in underwater explosion (UNDEX) problems by using the Moving Least Squares-Smoothed Particle Hydrodynamics (MLS-SPH) method, which is known as one of the particle methods suitable for problems where large deformation and inhomogeneity occur in the whole domain. Because the numerical oscillation of pressure arises from derivative discontinuity in the UNDEX analysis using the standard SPH method, the MLS shape function with Discontinuous-derivative Basis Function (DBF) that is able to represent the derivative discontinuity of field function is utilized in the MLS-SPH formulation in order to suppress the nonphysical pressure oscillation. The effectiveness of the MLS-SPH with DBF is demonstrated in comparison with the standard SPH and conventional MLS-SPH though a shock tube problem and benchmark standard problems of UNDEX of a trinitrotoluene (TNT) charge.

이방성 함유체가 포함된 무한고체의 효과적인 탄성해석을 위한 수치해석 방법 개발 (Development of a Numerical Method for Effective Elastic Analysis of Unbounded Solids with Anisotropic Inclusions)

  • 최성준;이정기
    • 한국전산구조공학회:학술대회논문집
    • /
    • 한국전산구조공학회 1998년도 봄 학술발표회 논문집
    • /
    • pp.41-52
    • /
    • 1998
  • A volume integral equation method and a mixed volume and boundary integral equation method are presented for the solution of plane elastostatic problems in solids containing orthotropic inclusions and voids. The detailed analysis of the displacement and stress fields are developed for orthotropic cylindrical and elliptic-cylindrical inclusions and voids. The accuracy and effectiveness of the new methods are examined through comparison with results obtained from analytical and boundary integral equation methods. Through the analysis of plane elastostatic problems in unbounded isotropic matrix containing orthotropic inclusions and voids, it is established that these new methods are very accurate and effective for solving plane elastostatic and elastodynamic problems in unbounded solids containing general anisotropic inclusions and voids or cracks.

  • PDF

Symbiotic Organisms Search for Constrained Optimization Problems

  • Wang, Yanjiao;Tao, Huanhuan;Ma, Zhuang
    • Journal of Information Processing Systems
    • /
    • 제16권1호
    • /
    • pp.210-223
    • /
    • 2020
  • Since constrained optimization algorithms are easy to fall into local optimum and their ability of searching are weak, an improved symbiotic organisms search algorithm with mixed strategy based on adaptive ε constrained (ε_SOSMS) is proposed in this paper. Firstly, an adaptive ε constrained method is presented to balance the relationship between the constrained violation degrees and fitness. Secondly, the evolutionary strategies of symbiotic organisms search algorithm are improved as follows. Selecting different best individuals according to the proportion of feasible individuals and infeasible individuals to make evolutionary strategy more suitable for solving constrained optimization problems, and the individual comparison criteria is replaced with population selection strategy, which can better enhance the diversity of population. Finally, numerical experiments on 13 benchmark functions show that not only is ε_SOSMS able to converge to the global optimal solution, but also it has better robustness.