National Taiwan Ocean University Research Hubhttps://scholars.ntou.edu.twThe DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Mon, 04 Nov 2024 20:49:10 GMT2024-11-04T20:49:10Z5061A study on the degenerate scale by using the fundamental solution with dimensionless argument for 2D elasticity problemshttp://scholars.ntou.edu.tw/handle/123456789/1059Title: A study on the degenerate scale by using the fundamental solution with dimensionless argument for 2D elasticity problems
Authors: Jeng-Tzong Chen; Ying-Te Lee; Jia-Wei Lee; Sheng-Kuang Chen
Abstract: The influence matrix may be of deficient rank in the specified scale when we have solved the 2D elasticity problem by using the boundary element method (BEM). This problem stems from lnr in the 2D Kelvin solution. On the other hand, the single-layer integral operator can not represent the constant term for the degenerate scale in the boundary integral equation method (BIEM). To overcome this problem, we have proposed the enriched fundamental solution containing an adaptive characteristic length to ensure that the argument in the logarithmic function is dimensionless. The adaptive characteristic length, depending on the domain, differs from the constant base by adding a rigid body mode. In the analytical study, the degenerate kernel for the fundamental solution in polar coordinates is revisited. An adaptive characteristic length analytically provides the deficient constant term of the ordinary 2D Kelvin solution. In numerical implementation, adaptive characteristic lengths of the circular boundary, the regular triangular boundary and the elliptical boundary demonstrate the feasibility of the method. By employing the enriched fundamental solution in the BEM/BIEM, the results show the degenerate scale free.
Fri, 01 May 2020 00:00:00 GMThttp://scholars.ntou.edu.tw/handle/123456789/10592020-05-01T00:00:00ZMathematical analysis and treatment for the true and spurious eigenequations of circular plates by the meshless method using radial basis functionhttp://scholars.ntou.edu.tw/handle/123456789/1054Title: Mathematical analysis and treatment for the true and spurious eigenequations of circular plates by the meshless method using radial basis function
Authors: Jeng-Tzong Chen; Ying-Te Lee; I-Lin Chen; Kue-Hong Chen
Abstract: In this paper, a meshless method for solving the eigenproblems of plate vibration using the radial basis function (RBF) is proposed. By employing the RBF in the imaginary‐part fundamental solution, spurious eigenequations in conjunction with the true ones are obtained at the same time. Mathematical analysis for the appearance of spurious eigenequations by using degenerate kernel and circulant is done through a circular plate for a discrete system. In order to obtain the true and spurious eigenequations, six (C 2 4) formulations (either two combinations from the four types of potentials, single, double, triple and quadruple) of meshless methods are employed in conjunction with the SVD technique. The spurious eigenequation in each formulation is found and is filtered out by using the SVD updating technique. Three cases, clamped, simply‐supported and free circular plates, are demonstrated to check the validity of the meshless methods.
Thu, 01 Jul 2004 00:00:00 GMThttp://scholars.ntou.edu.tw/handle/123456789/10542004-07-01T00:00:00ZOptimizing deployment of sponge zone on numerical wave channelhttp://scholars.ntou.edu.tw/handle/123456789/19599Title: Optimizing deployment of sponge zone on numerical wave channel
Authors: Chung‐Ren Chou; John‐Z Yim; Ruey-Syan Shih
Abstract: In this study, we used the boundary element method to simulate a two‐dimensional wave tank with an absorbing boundary. The absorbing boundary, which consists of a sponge zone, is further divided into an area with a smoothly varied absorption coefficient μ and an area of constant μ. Both solitary, as well as periodic, waves are used in this study. Time histories of surface elevations are measured by a pseudo wave gage. The optimal combination of the absorption coefficient and sponge length to minimize wave reflection is investigated by studying these time series. The efficiency of the absorption zone is demonstrated by the attenuation rate of the wave energy, which for cases can reach a value of 100%. Based upon the present results, it is recommended that in simulating solitary waves, a value of μ 0=0.5 for the absorption coefficient with a sponge length of 15∼25 times the water depth is ideal, whereas a value of μ 0=1.0 in combination with a sponge length 20 times the water depth should be used for periodic waves.
Tue, 01 Jan 2002 00:00:00 GMThttp://scholars.ntou.edu.tw/handle/123456789/195992002-01-01T00:00:00ZLearning temporal sequences using dual-weight neuronshttp://scholars.ntou.edu.tw/handle/123456789/16961Title: Learning temporal sequences using dual-weight neurons
Authors: Jung-Hua Wang; Tsai, MC; Su, WS
Abstract: This paper considers the use of neural networks (NN 's) in learning temporal sequence recognition and reproduction for which the sequence degree is unknown. This approach uses the output ambiguity to train the network without the need to assume or construct a separate model fur the input sequence degree. First we introduce a primitive network called the DNN, comprising a plurality of dual-weight (DN) neurons. Each neuron is linked to other neurons by a long-term excitatory weight and a short-term inhibitory weight. Fast learning is made possible by employing a two-pass training rule to encode the temporal distance between two arbitrary pattern occurrences. The resulting DNN is then extended into a more generalized model, namely the DNN2. By incorporating the two-pass rule and a self-organizing algorithm, the DNN2 can achieve autonomous temporal sequence recognition acid reproduction. Using training efficiency and hardware complexity criteria, the DNN networks are also contrasted with the work of Wang and Yuwono (1995).
Tue, 01 May 2001 00:00:00 GMThttp://scholars.ntou.edu.tw/handle/123456789/169612001-05-01T00:00:00ZDual boundary element analysis for fatigue behavior of missile structureshttp://scholars.ntou.edu.tw/handle/123456789/2484Title: Dual boundary element analysis for fatigue behavior of missile structures
Authors: Shiang-Woei Chyuan; Jiann-Hwa Lin; Jeng-Tzong Chen; Dauh-Churn Liu
Abstract: The fatigue behavior of a crack in a missile structure is studied using the dual boundary integral equations developed by Hong and Chen (1988). This method, which incorporates two independent boundary integral equations, uses the displacement equation to model one of the crack boundaries and the traction equation to the other. A single domain approach can be performed efficiently. The stress intensity factors are calculated and the paths of crack growth are predicted. In order to evaluate the results of dual BEM, four examples with FEM results are provided. Two practical examples, cracks in a V‐band and a solid propellant motor are studied and are compared with experimental data. Good agreement is found.本文使用洪及陳(1988)所發展的對偶邊界元素法分析飛彈結構的疲勞行為。此方法結合二個獨立的邊界積分方程式，兩式可同時考慮裂縫邊界的兩側，有效地使用單一領域即可處理裂縫問題。包括應力強度因子的計算結果以及裂縫成長路徑之預測，將與影線元素法做比較。其中有二個實際應用例分別為含裂縫之V型環以及固體火箭發動機，經與實驗結果做比較，可得到一致的結果。
Mon, 01 May 2000 00:00:00 GMThttp://scholars.ntou.edu.tw/handle/123456789/24842000-05-01T00:00:00ZA nonsingular integral formulation for the Helmholtz eigenproblems of a circular domainhttp://scholars.ntou.edu.tw/handle/123456789/2391Title: A nonsingular integral formulation for the Helmholtz eigenproblems of a circular domain
Authors: Jeng-Tzong Chen; Shyh-Rong Kuo; Kwe-Hoo Chen
Abstract: A nonsingular integral formulation for the Helmholtz eigenproblem is developed in this paper. This novel method contains only imaginary‐part kernels instead of complex‐part kernels in the complex‐valued BEM. Based on the imaginary‐part formulation without singular source, no singular or hypersingular integrals are present. Although this formulation avoids the computation of singular and hypersingular integrals, this approach results in spurious eigensolutions. After comparing the results from the dual formulation, the true and spurious solutions can be separated. An analytical example for the eigensolutions of a two‐dimensional circular domain is studied. The continuous system can be transformed to a discrete system with circulants. Based on the spectral properties of circulants, the true and spurious solutions for the eigenvalues, boundary modes, interior modes and multiplicities are all examined. The possible failure of Hutchinson's sorting technique of looking at modal shapes is also discussed.本文針對Helmholtz特徵值問題發展一非奇異積分推導解法。此法僅採用負數核函數中的虛部。基於此不含奇異元的輔助系統，奇異與超奇異積分將不會出現。然而，卻會導致假的特徵解。配合對偶架構後，真假特徵解可被分辨出來。利用循環對稱矩陣可解析的特性，一個圓形範例，將可解析推導並說明真假特徵解的發生機制。同時，包括真假特徵值、真假特徵邊界狀態、真假內域模態與真假重根數均有所探討。另Hutchinson由模態鑑別真假解的技巧可行性，在本文亦加以討論。
Mon, 01 Nov 1999 00:00:00 GMThttp://scholars.ntou.edu.tw/handle/123456789/23911999-11-01T00:00:00Z