• Title/Summary/Keyword: dual matrix

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Computation of dynamic stiffness and flexibility for arbitrarily shaped two-dimensional membranes

  • Chen, J.T.;Chung, I.L.
    • Structural Engineering and Mechanics
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    • v.13 no.4
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    • pp.437-453
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    • 2002
  • In this paper, dynamic stiffness and flexibility for circular membranes are analytically derived using an efficient mixed-part dual boundary element method (BEM). We employ three approaches, the complex-valued BEM, the real-part and imaginary-part BEM, to determine the dynamic stiffness and flexibility. In the analytical formulation, the continuous system for a circular membrane is transformed into a discrete system with a circulant matrix. Based on the properties of the circulant, the analytical solutions for the dynamic stiffness and flexibility are derived. In deriving the stiffness and flexibility, the spurious resonance is cancelled out. Numerical aspects are discussed and emphasized. The problem of numerical instability due to division by zero is avoided by choosing additional constraints from the information of real and imaginary parts in the dual formulation. For the overdetermined system, the least squares method is considered to determine the dynamic stiffness and flexibility. A general purpose program has been developed to test several examples including circular and square cases.

Digital Control for Takagi-Sugeno Fuzzy System with Multirate Sampling

  • Kim, Do Wan;Joo, Young Hoon;Park, Jin Bae
    • International Journal of Fuzzy Logic and Intelligent Systems
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    • v.4 no.2
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    • pp.199-204
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    • 2004
  • In this paper, a new dual-rate digital control technique for the Takagi-Sugeno (T-S) fuzzy system is suggested. The proposed method takes account of the stabilizablity of the discrete-time T-S fuzzy system at the fast-rate sampling points. Our main idea is to utilize the lifted control input. The proposed approach is to obtain the dual-rate discrete-time T-S fuzzy system by discretizing the overall dynamics of the T-S fuzzy system with the lifted control, and then to derive the sufficient conditions for the stabilization in the sense of the Lyapunov asymptotic stability for this system. An example is provided for showing the feasibility of the proposed discretization method.

Stationary Dual-Porosity Fractal Model of Groundwater Flow in Fractured Aquifers (균일대수층내 지하수 유동에 관한 정상류의 이중공극 프락탈 모델)

  • ;Bidaux, Pasal
    • The Journal of Engineering Geology
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    • v.4 no.2
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    • pp.127-138
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    • 1994
  • The stationary dual-porosity model is not sufficient to describe the hydraulic characteristics of fractured aquifers as the groundwater flow in fractured aquifers is often controlled by the fractal geometry of fractures. This study deals with new stationary dual-porosity fractal model. This model simulates pseudo-steady state flow from matrix block to fissure in the fractal aquifer. Furthermore, it considers storage capacity and well loss effect at the production well. Type curves for different flow dimensions with different drainage factors are plotted. This new model has been applied to experimental data. The result of the interpretation shows a good accordance between the theoretical model and the observed data.

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Generation of Fixed Spectral Basis for Three-Dimensional Mesh Coding Using Dual Graph

  • Kim Sung-Yeol;Yoon Seung-Uk;Ho Yo-Sung
    • Proceedings of the IEEK Conference
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    • summer
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    • pp.137-142
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    • 2004
  • In this paper, we propose a new scheme for geometry coding of three-dimensional (3-D) mesh models using a fixed spectral basis. In order to code the mesh geometry information, we generate a fixed spectral basis using the dual graph derived from the 3-D mesh topology. After we partition a 3-D mesh model into several independent sub-meshes to reduce coding complexity, the mesh geometry information is projected onto the generated orthonormal bases which are the eigenvectors of the Laplacian matrix of the 3-D mesh. Finally, spectral coefficients are coded by a quantizer and a variable length coder. The proposed scheme can not only overcome difficulty of generating a fixed spectral basis, but also reduce coding complexity. Moreover, we can provide an efficient multi-resolution representation of 3-D meshes.

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In-situ TEM investigation of zirconium alloy under Kr+ single-beam and Kr+-He+ dual-beam synergetic irradiation

  • Zhen Wang;Qing-Xue Yan;Zhong-Qiang Fang;Chen-Yang Lu
    • Nuclear Engineering and Technology
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    • v.56 no.8
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    • pp.3129-3138
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    • 2024
  • The in-situ TEM irradiation experiments of zirconium alloy were conducted at 573 K, 673 K, and 773 K utilizing a 400 keV Kr + single beam and a 400 keV Kr+ and 30 keV He + dual beam. The results show that a large number of dislocation loops have been characterized in the matrix of the zirconium alloy under irradiation. With increasing the irradiation damage dose, some dislocation loops have reacted with one another to form a larger dislocation loop, which has finally formed dislocation lines or other defect structures. In zirconium alloys irradiated with Kr + single beam and Kr+ and He + dual-beam radiation, the proportion of <a> type dislocation loops with different Burgers vectors is essentially the same at low damage doses, but the proportion of interstitial type dislocation loops with the same Burgers vectors is obviously different. The amorphization of the second phase and the dissolution of the small-sized second phase were also pointed out. With the increase in temperature, the density of the dislocation loop in zirconium alloy gradually decreases, and the size of dislocation loop first increases and then decreases. Kr+ and He + dual beam irradiation increases the size of dislocation loops but decreases their density as compared with Kr + single beam irradiation.

Nonnegative Matrix Factorization Based Direction-of-Arrival Estimation of Multiple Sound Sources Using Dual Microphone Array (이중 마이크로폰을 이용한 비음수 행렬분해 기반 다중음원 도래각 예측)

  • Jeon, Kwang Myung;Kim, Hong Kook;Yu, Seung Woo
    • Journal of the Institute of Electronics and Information Engineers
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    • v.54 no.2
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    • pp.123-129
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    • 2017
  • This paper proposes a new nonnegative matrix factorization (NMF) based direction-of-arrival (DOA) estimation method for multiple sound sources using a dual microphone array. First of all, sound signals coming from the dual microphone array are segmented into consecutive analysis frames, and a steered-response power phase transform (SRP-PHAT) beamformer is applied to each frame so that stereo signals of each frame are represented in a time-direction domain. The time-direction outputs of SRP-PHAT are stored for a pre-defined number of frames, which is referred to as a time-direction block. Next, In order to estimate DOAs robust to noise, each time-direction block is normalized along the time by using a block subtraction technique. After that, an unsupervised NMF method is applied to the normalized time-direction block in order to cluster the directions of each sound source in a multiple sound source environments. In particular, the activation and basis matrices are used to estimate the number of sound sources and their DOAs, respectively. The DOA estimation performance of the proposed method is evaluated by measuring a mean absolute error (MAE) and the standard deviation of errors between the oracle and estimated DOAs under a three source condition, where the sources are located in [$-35{\circ}$, 5m], [$12{\circ}$, 4m], and [$38{\circ}$, 4.m] from the dual microphone array. It is shown from the experiment that the proposed method could relatively reduce MAE by 56.83%, compared to a conventional SRP-PHAT based DOA estimation method.

Nondestructive Evaluation and Microfailure Modes of Single Fibers/Cement Composites using Electro-Micromechanical Technique and Acoustic Emission (Electro-Micromechanical 시험법과 음향방출을 이용한 단섬유시멘트복합재료의 미세파괴구조와 비파괴적 평가)

  • Lee, Sang-Il;Kim, Jin-Won;Park, Joung-Man;Yoon, Dong-Jin
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2001.05a
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    • pp.258-262
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    • 2001
  • The contact resistivity was correlated with IFSS and microfailure modes in conductive fiber/cement composites electro-pullout and AE. As IFSS increased, the number of AE signals increased and the contact resistivity increased latter to the infinity. In dual matrix composite (DMC) test and AE, the number of signals with high amplitude and energy in g]ass fiber composite is significantly larger than that of no-fiber composite. Many vertical and diagonal cracks were observed in glass fiber and no-fiber composite under tensile test, respectively. Electro-micromechanical technique and AE can be used efficiently for sensitive nondestructive (NDT) evaluation and to detect microfailure mechanisms in various conductive fibers reinforced brittle and nontransparent cement composites.

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Dual Modulation Driving for Poly-Si TFT Active Matrix OLED Displays (다결정 실리콘 박막 트랜지스터 Active Matrix OLED 디스플레이를 위한 이중 변조 구동)

  • 김재근;정주영
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.41 no.10
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    • pp.17-22
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    • 2004
  • We developed a new ANGLED display driving method which used both amplitude and pulse width modulation. For pulse width modulation, we divided a picture frame time into S sub-frames. For amplitude modulation, we used three OLED luminance(or current) levels which were controlled by TFT's gate voltages. By combining these two modulation methods, we obtained 35(=243) grey levels. And we designed a new data electrode driving circuit block with two shift registers without using DAC's. To verify the feasibility, we simulated the key circuit components by HSpice with TFT parameters extracted from current-voltage characteristics of 6${\mu}{\textrm}{m}$ channel length polysilicon TFT's. From the simulation results, we found that 320${\times}$240, dual scan, 243 grey level AMOLED display can be designed with this method.

The Thermal Shock Behaviors of Y-TZP/Y-TZP-Al2O3 Composites having Dual Microstructure (이중조직을 갖는 Y-TZP/Y-TZP-$Al_2O_3$ 복합체의 열충격 거동)

  • Hwang, K.H.;Kim, E.H.;Kim, Hwan
    • Journal of the Korean Ceramic Society
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    • v.29 no.4
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    • pp.283-292
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    • 1992
  • Duplex composites such as Y-TZP/Y-TZP-20 wt.% Al2O3 and Y-TZP/Y-TZP- 40 wt.% Al2O3 were made by mixing the sieve-shaked granules followed by isostatic pressing and sintering at 150$0^{\circ}C$ for 1 hour. So Y-TZP became matrix region and Y-TZP-20 wt.% Al2O3 or Y-TZP-40 wt.% Al2O3 became dispersed regions. In these composites, propagating cracks due to thermal shock always run into the dispersed region because these regions act as compressive zone due to low thermal expansion than matrix region. So duplexes having dispersed regions of Y-TZP-40 wt.% Al2O3 showed higher retained strength after thermal shock than matrix only composites because crack propagations were stopped more or less in the dispersed region. But when crack propagations were much more easy than matrix like Y-TZP-20 wt.% Al2O3 region, retained strength was decreased than the matrix only composites despite of the low initial strength.

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