• Title/Summary/Keyword: Multi-block Technique

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A Study on Multi-Block Technique by Bi-CGSTAB Solver (Bi-CGSTAB 해법에 의한 복합격자망 해석방법에 관한 연구)

  • Bae, Jin-Hyo;Lee, Jae-Heon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.8
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    • pp.2611-2625
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    • 1996
  • A numerical method on multi-block technique by Bi-CGSTAB(Bi-Conjugate Gradient STABilized) solver has been proposed. The present multi-block technique can reduce the numerical manipulation greatly because the common regions at the interface of each block are not necessary. In order to test the computational performance of present multi-block technique, the flow characteristics in a T type duct system and a N type duct system have been investigated by three kinds of methods such as the single-block method, the previous multi-block technique and the multi-block technique with Bi-CGSTAB solver. The results indicated that the required CPU time by present multi block technique was shorter than that of other two numerical methods and the convergency history was shown very stable at the present multi-block technique.

Automatic Multi-Block Grid Generation Technique Based on Delaunay Triangulation (Delaunay 삼각화 기법을 활용한 다중-블록 정렬 격자의 자동 생성 기법)

  • Kim Byoungsoo
    • 한국전산유체공학회:학술대회논문집
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    • 1999.11a
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    • pp.108-114
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    • 1999
  • In this paper. a new automatic multi=block grid generation technique for general 2D regions is introduced. According to this simple and robust method, the domain of interest is first triangulated by using Delaunay triangulation of boundary points, and then geometric information of those triangles is used to obtain block topology. Once block boundaries are obtained. structured grid for each block is generated such that grid lines have $C^0-continuity$ across inter-block boundaries. In the final step of the present method, an elliptic grid generation method is applied to smoothen grid distribution for each block and also to re-locale the inter-block boundaries, and eventually to achieve a globally smooth multi-block structured grid system with $C^1-continuity$.

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Parallelization of Multi-Block Flow Solver with Multi-Block/Multi-Partitioning Method (다중블록/다중영역분할 기법을 이용한 유동해석 코드 병렬화)

  • Ju, Wan-Don;Lee, Bo-Sung;Lee, Dong-Ho;Hong, Seung-Gyu
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.7
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    • pp.9-14
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    • 2003
  • In this work, a multi-block/multi-partitioning method is suggested for a multi-block parallelization. It has an advantage of uniform load balance via subdividing of each block on each processor. To make a comparison of parallel efficiency according to domain decomposition method, a multi-block/single-partitioning and a multi-block/ multi-partitioning methods are applied to the flow analysis solver. The multi-block/ multi-partitioning method has more satisfactory parallel efficiency because of optimized load balancing. Finally, it has applied to the CFDS code. As a result, the computing speed with sixteen processors is over twelve times faster than that of sequential solver.

Design of Multi-Input Multi-Output Positive Position feedback Controller based on Block-Inverse Technique (블록 역행렬 기법에 의한 다중입출력 양변위 되먹임제어기의 설계)

  • Kwak, Moon-K.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.508-514
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    • 2005
  • This paper is concerned with the active vibration control of a grid structure equipped with piezoceramic sensors and actuators. The grid structure is a replica of the solar panel commonly mounted on satellites, which contains complex natural mode shapes. The multi input and multi output positive position feedback controller is considered as an active vibration controller for the grid structure. A new concept, the block-inverse technique, is proposed to cope with more modes than the number of actuators and sensors. This study also deals with the stability and the spillover effect associated with the application of the multi-input multi-output positive position feedback controller based on the block inverse technique. It was found that the theories developed in this study are capable of predicting the control system characteristics and its performance. The new multi-input multi-output positive position feedback controller was applied to the test structure using a digital signal processor and its efficacy was verified by experiments..

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Design of Multi-input Multi-output Positive Position Feedback Controller Based on Block-inverse Technique (블록 역행렬 기법에 의한 다중입출력 양변위 되먹임제어기의 설계)

  • Kwak, Moon K.
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.9 s.102
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    • pp.1037-1044
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    • 2005
  • This paper is concerned with the active vibration control of a grid structure equipped with piezoceramic sensors and actuators. The grid structure is a replica of the solar panel commonly mounted on satellites, which contains complex natural mode shapes. The multi-input and multi-output positive position feedback controller is considered as an active vibration controller for the grid structure. A new concept, the block-inverse technique, is proposed to cope with more modes than the number of actuators and sensors. This study also deals with the stability and the spillover effect associated with the application of the multi-input multi-output positive position feedback controller based on the block-inverse technique. It was found that the theories developed in this study are capable of predicting the control system characteristics and its performance. The new multi-input multi-output positive position feedback controller was applied to the test structure using a digital signal processor and its efficacy was verified by experiments.

A NTSS of 3 Levels Block Matching Algorithm using Multi-Resolution (다중해상도를 이용한 새로운 3단계 블록정합 알고리즘)

  • Joo Heon-Sik
    • The KIPS Transactions:PartB
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    • v.11B no.6
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    • pp.633-644
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    • 2004
  • In this paper, we notice that the original NTSS algorithm can be proposed as the NTSS-3 Level algorithm by the multi-resolution technique. The fast block matching algorithm affects the speed by the patten combination and this paper proposes the block matching algorithm in different levels by multi-resolution technique, quite different from the original NTSS Patten. The block matching algorithm requires the multi-candidate to reduce the occurrence of low-image quality by the local minima problem. The simulation result compared to FS shows search speed 16 times quicker, and the PSNR 0.11-0.12[dB] gets improved Image quality compared to the original fast block matching algorithm NTSS, and the speed is improved up to 0.1 times for improved image by the search point portion.

A Study on the OFDM System Using Multi-Block SDM (Multi-Block SDM을 이용한 OFDM 시스템에 관한 연구)

  • Lee, Kyu-Jin;Kim, Ji-Sung;Kim, Nam-Il;Lee, Kye-San
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.7 no.5
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    • pp.122-130
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    • 2008
  • Improving the transmission rates of multi-media delivery, such as moving pictures and internet services, has become increasingly important in modern society. To satisfy such high data rate requirements, the MIMO technique, which has the capacity to transmit large amounts of data using limited frequency resources, was developed. The Space Division Multiplexing (SDM) system is one of the MIMO techniques to be able to improve the transmission capacity. However, it is unable to achieve diversity gain because of interference due to the use of multiple antennas. In this paper, an SDM system that utilizes a Multi-Block method as an advanced transmission technique in a wireless communication system to obtain diversity gain is proposed and discussed fur the performance of the proposed system.

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Block-Ordered Layered Detector for MIMO-STBC Combined with Transmit and Receive Eigen-Beamformers (MIMO-STBC를 위한 송수신 고유빔 형성기를 이용한 블록순 계층적 검파기)

  • 이원철;김홍철
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.41 no.10
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    • pp.17-26
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    • 2004
  • This paper proposes JBSTBC (Joint Beamforming Space-Time Block Coding) scheme for MIMO (Multi-Input Multi-Output) communication systems. To enhance the order of spatial diversity in presence of deteriorative fading correlations as well as inter-substream interferences, the proposed JBSTBC method employs joint eigen-beamforming technique together with the BOLD (block-ordered layered detector) for MIMO-STBC. In order to confirm superiority of the proposed JBSTBC method, the computer simulations are conducted in highly correlated fading situations with providing detailed mathematical derivations for clarifying functionality of the proposed scheme.

Research on the PAPR Reduction Method using Selection of Extra Code Set in PB/MC-CDMA System (PB/MC-CDMA 시스템에서 여분의 코드집합을 이용한 PAPR 감쇄기법에 관한 연구)

  • Lee, Kyu-Jin;Lee, Dong-Joon;Lee, Kye-San;Kim, Jin-Young
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.8 no.1
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    • pp.110-118
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    • 2009
  • The PB/MC-CDMA(Partial Block Multi Carrier Code Division Multilple Access) system can improve the performance by reducing the ICI(Inter-Code Interference) between users. Also, this system can achieve the frequency diversity gain by avoiding ISI(Inter Symbol Interference). Therefore, the performance of PB/MC-CDMA system is better than that of conventional MC-CDMA(Multi Carrier Code Division Multiple Access) system. However, similarly to other multi-carrier systems, it still has a PAPR(Peak to Average Power Ratio) issue. In this paper, we propose a peak power reduction technique involving optimized spreading code selection without side information for the PB/MC-CDMA. The PB/MC-CDMA system in each block of units reuses the code so the extra code will be remained. This extra code is divided into several groups to calculate the PAPR and solving the PAPR problem by transferring the selected code which has minimum peak power.

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A PARALLEL PRECONDITIONER FOR GENERALIZED EIGENVALUE PROBLEMS BY CG-TYPE METHOD

  • MA, SANGBACK;JANG, HO-JONG
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.5 no.2
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    • pp.63-69
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    • 2001
  • In this study, we shall be concerned with computing in parallel a few of the smallest eigenvalues and their corresponding eigenvectors of the eigenvalue problem, $Ax={\lambda}Bx$, where A is symmetric, and B is symmetric positive definite. Both A and B are large and sparse. Recently iterative algorithms based on the optimization of the Rayleigh quotient have been developed, and CG scheme for the optimization of the Rayleigh quotient has been proven a very attractive and promising technique for large sparse eigenproblems for small extreme eigenvalues. As in the case of a system of linear equations, successful application of the CG scheme to eigenproblems depends also upon the preconditioning techniques. A proper choice of the preconditioner significantly improves the convergence of the CG scheme. The idea underlying the present work is a parallel computation of the Multi-Color Block SSOR preconditioning for the CG optimization of the Rayleigh quotient together with deflation techniques. Multi-Coloring is a simple technique to obatin the parallelism of order n, where n is the dimension of the matrix. Block SSOR is a symmetric preconditioner which is expected to minimize the interprocessor communication due to the blocking. We implemented the results on the CRAY-T3E with 128 nodes. The MPI(Message Passing Interface) library was adopted for the interprocessor communications. The test problems were drawn from the discretizations of partial differential equations by finite difference methods.

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