• 제목/요약/키워드: Diagonal Matrix

검색결과 258건 처리시간 0.027초

2×2 INVERTIBLE MATRICES OVER WEAKLY STABLE RINGS

  • Chen, Huanyin
    • 대한수학회지
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    • 제46권2호
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    • pp.257-269
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    • 2009
  • A ring R is a weakly stable ring provided that aR + bR = R implies that there exists $y\;{\in}\;R$ such that $a\;+\;by\;{\in}\;R$ is right or left invertible. In this article, we characterize weakly stable rings by virtue of $2{\times}2$ invertible matrices over them. It is shown that a ring R is a weakly stable ring if and only if for any $A\;{\in}GL_2(R)$, there exist two invertible lower triangular L and K and an invertible upper triangular U such that A = LUK, where two of L, U and K have diagonal entries 1. Related results are also given. These extend the work of Nagarajan et al.

불완전분해법을 전처리로 하는 공액구배법의 안정화에 대한 연구 (Study on Robustness of Incomplete Cholesky Factorization using Preconditioning for Conjugate Gradient Method)

  • 고진환;이병채
    • 대한기계학회논문집A
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    • 제27권2호
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    • pp.276-284
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    • 2003
  • The preconditioned conjugate gradient method is an efficient iterative solution scheme for large size finite element problems. As preconditioning method, we choose an incomplete Cholesky factorization which has efficiency and easiness in implementation in this paper. The incomplete Cholesky factorization mettled sometimes leads to breakdown of the computational procedure that means pivots in the matrix become minus during factorization. So, it is inevitable that a reduction process fur stabilizing and this process will guarantee robustness of the algorithm at the cost of a little computation. Recently incomplete factorization that enhances robustness through increasing diagonal dominancy instead of reduction process has been developed. This method has better efficiency for the problem that has rotational degree of freedom but is sensitive to parameters and the breakdown can be occurred occasionally. Therefore, this paper presents new method that guarantees robustness for this method. Numerical experiment shows that the present method guarantees robustness without further efficiency loss.

A Compliance Control Strategy for Robot Manipulators Under Unknown Environment

  • Kim, Byoung-Ho;Oh, Sang-Rok;Suh, Il-Hong;Yi, Byung-Ju
    • Journal of Mechanical Science and Technology
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    • 제14권10호
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    • pp.1081-1088
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    • 2000
  • In this paper, a compliance control strategy for robot manipulators that employs a self-adjusting stiffiness function is proposed. Based on the contact force, each entry of the diagonal stiffness matrix corresponding to a task coordinate in the operational space is adaptively adjusted during contact along the corresponding axis. The proposed method can be used for both the unconstrained and constrained motions without any switching mechanism which often causes undesirable instability and/or vibrational motion of the end-effector. The experimental results involving a two-link direct drive manipulator interacting with an unknown environment demonstrates the effectiveness of the proposed method.

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배전계통에서의 새로운 DistFlow Method에 대한 연구 (A Study for a Novel DistFlow Method in the Distribution System)

  • 곽도일;김재언
    • 대한전기학회논문지:전력기술부문A
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    • 제49권7호
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    • pp.365-368
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    • 2000
  • Traditionally, load flows have been calculated using the Gauss-Seidel and Newton-Raphson Method. DistFlow Method which is proposed by Wu and Baran is superior to the other two methods because it does not require the admittance matrix calculation to optimize the distribution system. This paper introduces a new alternative algorithm to the DistFlow Method which is slow and complex to find solutions as the number of lateral and sublateral increases. The proposed load flow method can construct System Jacobian easily. We can minimize the off-diagonal elements of the branch Jacobian and submatrices in the System Jacobian. Simulation results show that progressive performances of the proposed algorithm have a better convergence time.

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6자유도 진동 흡진기의 기하적 설계 이론 (Geometrical Design Theory of a 6 DOF Vibration Absorber)

  • 장선준;최용제
    • 한국정밀공학회지
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    • 제22권7호
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    • pp.191-199
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    • 2005
  • Many researchers have been investigating the design of multi-mode absorption vibration absorber for multi degree-of-freedom (DOF) system. The approach taken to this problem has been to find the optimized constants of stiffness and damping for the given set of single-DOF absorbers or single multi-DOF absorber attached to a multi degree-of-freedom system. This paper presents a novel geometrical and direct design theory of a 6 DOF vibration absorber via screw theory. Theoretical development is demonstrated by a practical example in which the diagonal stiffness matrix is synthesized using rectangular configuration of springs. The performance of this absorber is simulated by modal analysis.

특이공간 회피에 의한 2차 비선형 시스템의 스위칭 제어기 설계 (Switching Control for End Order Nonlinear Systems by Avoiding Singular Manifolds)

  • 염동회;임기홍;최진영
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 A
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    • pp.315-318
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    • 2003
  • This paper proposes a switching control method applicable to any affine, 2nd order nonlinear system with single input. The key contribution is to develop a control design method which uses a piecewise continuous Lyapunov function non-increasing at every discontinuous point. The proposed design method requires no restrictions except full state availability. To obtain a non-increasing, piecewise continuous Lyapunov function, we change the sign of off-diagonal term s of the positive definite matrix composing the former Lyapunov function according to the sign of the Inter-connection term. And we use the solution of inequalities which guarantee each Lyapunov function is non-increasing at any discontinuous point.

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A study on the Interfacial Properties of Electrodeposited Single Carbon Fiber/Epoxy Composites Using Tensile and Compressive Fragmentation Tests

  • Park, Joung-Man;Kim, Jin-Won
    • Macromolecular Research
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    • 제10권1호
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    • pp.24-33
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    • 2002
  • Interfacial and microfailure properties of carbon fiber/epoxy composites were evaluated using both tensile fragmentation and compressive Broutman tests. A monomeric and two polymeric coupling agents were applied via the electrodeposition (ED) and the dipping applications. A monomeric and a polymeric coupling agent showed significant and comparable improvements in interfacial shear strength (IFSS) compared to the untreated case under both tensile and compressive tests. Typical microfailure modes including cone-shaped fiber break, matrix cracking, and partial interlayer failure were observed under tension, whereas the diagonal slipped failure at both ends of the fractured fiber appeared under compression. Adsorption and shear displacement mechanisms at the interface were described in terms of electrical attraction and primary and secondary bonding forces.

Comparisons of Multivariate Quality Control Charts by the Use of Various Correlation Structures

  • Choi, Sung-Woon;Lee, Sang-Hoon
    • 한국경영과학회지
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    • 제20권3호
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    • pp.123-146
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    • 1995
  • Several quality control schemes have been extensively compared using multivariate normal data sets simulated with various correlation structures. They include multiple univariate CUSUM charts, multivariate EWMA charts, multivariate CUSUM charts and Shewhart T$^{3}$ chart. This paper considers a new approach of the multivariate EWMA chart, in which the smoothing matrix has full elements instead of only diagonal elements. Performance of the schemes is measured by avaerage run length (ARL), coefficient of variation of run length (CVRL) and rank in order of signaling of off-target shifts in the process mean vector. The schemes are also compared by noncentrality parameter. The multiple univariate CUSUM charts are generally affected by the correlation structure. The multivariate EWMA charts provide better ARL performance. Especially, the new EWMA chart shows remarkable results in small shifts.

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화물열차용 제륜자의 열유동 해석 (Numerical Analysis on Heat Transfer and Fluid flow of Brake Shoe for Freight Car)

  • 남성원
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2001년도 춘계학술대회 논문집
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    • pp.123-128
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    • 2001
  • Numerical simulation is conducted to clarify the heat transfer and fluid flow characteristics of brake shoe for freight car. High order up-wind scheme for governing equations, k-epsilon turbulent model and SIMPLEC algorithm based on finite volume method are used to solve the physical shoe model. The governing equations are solved by TDMA(Tri-Diagonal Matrix Algorithm) with line-by-line method and block correction. From the results of simulation, the characteristics of cooling pattern is strongly affected by the velocity of train and the material of shoe. The face lift of shoe affects on the temperature distribution of rear surface of shoe as well as the front surface of that. Due to the grooves in shoe, it will be expected to cool the frictional heat and result in the reduction of maintenance efforts.

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MP-2에서의 타원형 편미분 방정식 병렬계산 (Parallel Computation of Elliptic Partial Differential Equation on MP-2)

  • 김형중;이용호
    • 산업기술연구
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    • 제14권
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    • pp.19-28
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    • 1994
  • 일반적으로 2차원 Poisson 방정식을 풀기 위해 유한 차분법을 이용하여 tridiagonal block Toeplitz 선형방정식을 얻는다. 이 선형방정식의 독특한 형태를 활용하기 위해 Lyapunov 방정식으로 변화시킨 다음 이산정현변환(DST)을 이용해서 대각선 행렬로 만들면 계산이 용이해진다. 또 DST는 FFT를 이용해 계산할 수 있으므로 고속 계산이 가능하다. FFT를 병렬로 처리하기 위해 프로세서가 4,096개인 SIMD 컴퓨터 MP-2에서 시뮬레이션했다. 본 논문에서는 알고리즘 유도, 매핑 및 시뮬레이션 결과를 제시했다.

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