• Title/Summary/Keyword: Iterative Calculation

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Hardware Implementation on the Weight Calculation of Iterative Algorithm for CT Image Reconstruction

  • Cao, Xixin;Ma, Kaisheng;Lian, Renchun;Zhang, Qihui
    • ETRI Journal
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    • v.35 no.5
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    • pp.931-934
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    • 2013
  • The weight calculation in an iterative algorithm is the most computationally costly task in computed tomography image reconstruction. In this letter, a fast algorithm to speed up the weight calculation is proposed. The classic square pixel rotation approximate calculation method for computing the weights in the iterative algorithm is first analyzed and then improved by replacing the square pixel model with a circular pixel model and the square rotation approximation with a segmentation method of a circular area. Software simulation and hardware implementation results show that our proposed scheme can not only improve the definition of the reconstructed image but also accelerate the reconstruction.

Location Error Reduction method using Iterative Calculation in UWB system (Iterative Calculation을 이용한 UWB 위치측정에서의 오차감소 기법)

  • Jang, Sung-Jeen;Hwang, Jae-Ho;Choi, Nack-Hyun;Kim, Jae-Moung
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.45 no.12
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    • pp.105-113
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    • 2008
  • In Ubiquitous Society, accurate Location Calculation of user's device is required to achieve the need of users. As the location calculation is processed by ranging between transceivers, if some obstacles exist between transceivers, NLoS(Non-line-of-Sight) components of received signal increase along with the reduction of LoS(Line-of-Sight) components. Therefore the location calculation error will increase due to the NLoS effect. The conventional location calculation algorithm has the original ranging error because there is no transformation of ranging information which degrades the ranging accuracy. The Iterative Calculation method which minimizes the location calculation error relys on accurately identifying NLoS or LoS condition of the tested channel. We employ Kurtosis, Mean Excess Delay and RMS Delay spread of the received signal to identify whether the tested channel is LoS or NLoS firstly. Thereafter, to minimize location calculation error, the proposed Iterative Calculation method iteratively select random range and finds the averaged target location which has high probability. The simulation results confirm the enhancement of the proposed method.

Parallel Algorithm of Improved FunkSVD Based on Spark

  • Yue, Xiaochen;Liu, Qicheng
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.15 no.5
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    • pp.1649-1665
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    • 2021
  • In view of the low accuracy of the traditional FunkSVD algorithm, and in order to improve the computational efficiency of the algorithm, this paper proposes a parallel algorithm of improved FunkSVD based on Spark (SP-FD). Using RMSProp algorithm to improve the traditional FunkSVD algorithm. The improved FunkSVD algorithm can not only solve the problem of decreased accuracy caused by iterative oscillations but also alleviate the impact of data sparseness on the accuracy of the algorithm, thereby achieving the effect of improving the accuracy of the algorithm. And using the Spark big data computing framework to realize the parallelization of the improved algorithm, to use RDD for iterative calculation, and to store calculation data in the iterative process in distributed memory to speed up the iteration. The Cartesian product operation in the improved FunkSVD algorithm is divided into blocks to realize parallel calculation, thereby improving the calculation speed of the algorithm. Experiments on three standard data sets in terms of accuracy, execution time, and speedup show that the SP-FD algorithm not only improves the recommendation accuracy, shortens the calculation interval compared to the traditional FunkSVD and several other algorithms but also shows good parallel performance in a cluster environment with multiple nodes. The analysis of experimental results shows that the SP-FD algorithm improves the accuracy and parallel computing capability of the algorithm, which is better than the traditional FunkSVD algorithm.

A Formulation of Iterative Eigenvalue Analysis Algorithm to the Second Order Newton Raphson Method (반복계산에 의한 고유치 해석 알고리즘의 2차 뉴튼랩슨법으로의 정식화)

  • Kim, Deok-Yeong
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.51 no.3
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    • pp.127-133
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    • 2002
  • This paper presents an efficient improvement of the iterative eigenvalue calculation method of the AESOPS algorithm. The intuitively and heuristically approximated iterative eigenvalue calculation method of the AESOPS algorithm is transformed to the Second Order Newton Raphson Method which is generally used in numerical analysis. The equations of second order partial differentiation of external torque, terminal and internal voltages are derived from the original AESOPS algorithm. Therefore only a few calculation steps are added to transform the intuitively and heuristically approximated AESOPS algorithm to the Second Order Newton Raphson Method, while the merits of original algorithm are still preserved.

Representation of Hull Form by Aitken's Iterative Interpolation Methods (逐次揷間法에 依한 船型의 數値表現法에 關하여)

  • Kim, Hyo-Chul;Yang, Yeong-Sun
    • Bulletin of the Society of Naval Architects of Korea
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    • v.14 no.3
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    • pp.1-4
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    • 1977
  • The computer aided ship design and construction has become very popular one in a ship yard recently. For one of such a purpose a program is developed with Aitken's iterative interpolation method. From the sample calculation we can conclude that the program has a reliable acquracy for the calculation of hydrostatic data or loading manual. And also the program can be applicable to a ship construction by careful selecting of input data.

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An Efficient Improvement of the Iterative Eigenvalue Calculation Method and the Selection of Initial Values in AESOPS Algorithm (AESOPS 알고리즘의 고유치 반복계산식과 고유치 초기값 선정의 효율적인 개선에 관한 연구)

  • Kim, Deok-Young;Kwon, Sae-Hyuk
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.11
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    • pp.1394-1400
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    • 1999
  • This paper presents and efficient improvement of the iterative eigenvalue calculation method and the selection of initial values in AESOPS algorithm. To determine the initial eigenvalues of the system, system state matrix is constructed with the two-axis generator model. From the submatrices including synchronous and damping coefficients, the initial eigenvalues are calculated by the QR method. Participation factors are also calculated from the above submatrices in order to determine the generators which have a important effect to the specific oscillation mode. Also, the heuristically approximated eigenvalue calculation method in the AESOPS algorithm is transformed to the Newton Raphson Method which is largely used in the nonlinear numerical analysis. The new methods are developed from the AESOPS algorithm and thus only a few calculation steps are added to practice the proposed algorithm.

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A New Kinematic Analysis of 6-3 Stewart Platform Manipulator (6-3 스튜워트 플랫폼 운동장치의 새로운 기구학 해석방법)

  • Kim, Nak-In;Lee, Chong-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.8
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    • pp.1206-1212
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    • 2001
  • The kinematic analysis of Stewart platform manipulator(SPM) is carried out in order to reduce the calculation time for its forward kinematic solution when the iterative numerical method is employed. The kinematic equations for three substructures of the 6-3 SPM are newly derived by introducing Denavit-Hartenberg link parameters and using kinematic constraints associated with the SPM and substructure kinematics. It is shown that the forward kinematics can be easily solved from three nonlinear equations with three unknown variables only, leading to a great reduction in calculation time.

Economic Dispatch Algorithm for Unit Commitment (기동정지계획을 위한 경제급전 알고리즘)

  • Park, Jeong-Do;Lee, Yong-Hoon;Kim, Ku-Han;Moon, Young-Hyun
    • Proceedings of the KIEE Conference
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    • 1999.07c
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    • pp.1506-1509
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    • 1999
  • This paper presents a new economic dispatch algorithm to improve the unit commitment solution while guaranteeing the near optimal solution without reducing calculation speed. The conventional economic dispatch algorithms have the problem that it is not applicable to the unit commitment formulation due to the frequent on/off state changes of units during the unit commitment calculation. Therefore, piecewise linear iterative method have generally been used for economic dispatch algorithm for unit commitment. In that method, the approximation of the generator cost function makes it hard to obtain the optimal economic dispatch solution. In this case, the solution can be improved by introducing a inverse of the incremental cost function. The proposed method is tested with sample system. The results are compared with the conventional piecewise linear iterative method. It is shown that the proposed algorithm yields more accurate and economical solution without calculation speed reduction.

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Acceleration of the Iterative Physical Optics Using Graphic Processing Unit (GPU를 이용한 반복적 물리 광학법의 가속화에 대한 연구)

  • Lee, Yong-Hee;Chin, Huicheol;Kim, Kyung-Tae
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.26 no.11
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    • pp.1012-1019
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    • 2015
  • This paper shows the acceleration of iterative physical optics(IPO) for radar cross section(RCS) by using two techniques effectively. For the analysis of the multiple reflection in the cavity, IPO uses the near field method, unlike shooting and bouncing rays method which uses the geometric optics(GO). However, it is still far slower than physical optics(PO) and it is needed to accelerate the speed of IPO for practical purpose. In order to address this problem, graphic processing unit(GPU) can be applied to reduce calculation time and adaptive iterative physical optics-change rate(AIPO-CR) method is also applicable effectively to optimize iteration for acceleration of calculation.

Extended Noniterative Algorithm Using Multi-machine Two-Axis Model for Transient Stability Analysis (과도 안정도 해석을 위한 다기 계통 2축 모델을 이용한 확장 비반복 알고리즘)

  • Jin, Won-Suk;Kwon, Yong-Jun;Moon, Young-Hyun;Choi, Byoung-Kon
    • Proceedings of the KIEE Conference
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    • 2003.07a
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    • pp.125-127
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    • 2003
  • The Conventional time-domain simulation of transient stability requires iterative calculation procedures to consider the saliency of generator. Recently, a non-iterative algorithm has successfully developed to take into account the generator saliency exactly with the use of $E_q'$-model. This study proposes an extended non-iterative algorithm by adopting the two-axis generator model. Given internal voltages and rotor angles of the generators, network voltages and generator currents can be directly calculated by solving a linear algebraic equation, which enables us to reduce the computation time remarkably.

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