• Title/Summary/Keyword: Linear Complexity

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IMC design for nonlinear plants using multiple models, controllers, and switching (다중 모델, 제어기, 스위칭을 이용한 비선형 플랜트의 IMC 제어기 설계)

  • 오원근;서병설
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.11
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    • pp.22-30
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    • 1996
  • In this paper, the properties and the design procedures of the internal model control (IMC) structures are discussed and a new nonlinear IMC(NIMC) strategy is proposed. The IMC controllers are simply inverse controller in principle but the development of a NIMC poses difficulties due to the inherent complexity of nonlinear systems. Existing design mehtods are a few and not easy to implement. The proposed approach is using multiple linear models, linear IMC controllers, and swiching scheme instead of using nonlinear model/controller. The advantages of the new approach are that we can use linear IMC mehtod which are now well estabilished and need not global nonlinear models.

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Bounds for Stationary Waiting Times in a Class of Queueing Networks using Stochastic Ordering (확률적 순서를 이용한 대기행렬 망에서 안정 대기시간의 범위)

  • Seo Dong-Won
    • Journal of the Korean Operations Research and Management Science Society
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    • v.29 no.4
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    • pp.1-10
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    • 2004
  • In this paper we study bounds for characteristics of stationary waiting times in (max, +)-linear systems with a Poisson arrival process. which are prevalent in manufacturing systems, kanban systems, cyclic and acyclic fork-and-join type systems, finite or infinite capacity tandem queues with various kinds of blocking, transportation systems, and telecommunication networks, and so on. Recently, some results on series expansion for characteristics, such as higher moments, Laplace transform, and tail probability, of transient and stationary waiting times in a class of (max, +)-linear systems via Taylor series expansions have been studied. In order to overcome the computational complexity in those results, we consider bounds for characteristics of stationary waiting times using valuable stochastic ordering results. Some numerical examples are also provided.

Constant Time RMESH Algorithm to Find Neighbor Blocks in Linear Quadtrees (선형 사진트리에서 이웃 블록을 찾기 위한 상수시간 RMESH 알고리즘)

  • Kim, Gi-Won;U, Jin-Un
    • The Transactions of the Korea Information Processing Society
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    • v.6 no.1
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    • pp.66-74
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    • 1999
  • A linear quadtree representation as a way to store a quadtree is efficient to save space compared with other representations. It , therefore, has been widely studied to develop efficient algorithms to execute operations related with quadtrees. In this paper, we present algorithm to find neighbor blocks of binary images represented by linear quadtrees, using three-dimensional n${\times}$n${\times}$n processors on RMESH(Reconfigurable MESH). Pur algorithm have O(1) time complexity.

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A Closed-Form Solution of Linear Spectral Transformation for Robust Speech Recognition

  • Kim, Dong-Hyun;Yook, Dong-Suk
    • ETRI Journal
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    • v.31 no.4
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    • pp.454-456
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    • 2009
  • The maximum likelihood linear spectral transformation (ML-LST) using a numerical iteration method has been previously proposed for robust speech recognition. The numerical iteration method is not appropriate for real-time applications due to its computational complexity. In order to reduce the computational cost, the objective function of the ML-LST is approximated and a closed-form solution is proposed in this paper. It is shown experimentally that the proposed closed-form solution for the ML-LST can provide rapid speaker and environment adaptation for robust speech recognition.

A Study on the Linear Motor Control System (니리어모터 이송계 제어 특성분석에 관한 연구)

  • Yoo, Song-Min
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2003.04a
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    • pp.466-471
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    • 2003
  • In order to analyze linear motor driven feed system, preliminary studies have been conducted focusing on the performance evaluation of the system based on the various combination of control gain along with acceleration. Tentative simulation revealed that due to the complexity of control system reduced number of control condition is recommended. Actual machining process with conventional feed system using endmill tool was employed as a preliminary study. Several sensing methods including AE, acceleration sensors and tool dynamometer were used. Results revealed the consistency in AE and cutting resistance. There were inconsistent empirical results in accelerometer probably due to the insensitivity of the sensor signal with respect to the experimental system

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Automated yield-line analysis of beam-slab systems

  • Johnson, David
    • Structural Engineering and Mechanics
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    • v.3 no.6
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    • pp.529-539
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    • 1995
  • The rigid-plastic yield-line analysis of isotropically reinforced concrete slabs acting in conjunction with torsionally weak supporting beams is developed as the lower-bound form of a linear programming formulation. The analysis is extended to consider geometric variation of chosen yield-line patterns by the technique of sequential linear programming. A strategy is followed of using a fine potential yield-line mesh to identify possible collapse modes, followed by analysis using a coarser, simplified mesh to refine the investigation and for use in conjunction with geometric optimization of the yield-line system. The method is shown to be effective for the analysis of three slabs of varying complexity. The modes detected by the fine and simplified analyses are not always similar but close agreement in load factors has been consistently obtained.

REPRODUCING KERNEL METHOD FOR SOLVING TENTH-ORDER BOUNDARY VALUE PROBLEMS

  • Geng, Fazhan;Cui, Minggen
    • Journal of applied mathematics & informatics
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    • v.28 no.3_4
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    • pp.813-821
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    • 2010
  • In this paper, the tenth-order linear boundary value problems are solved using reproducing kernel method. The algorithm developed approximates the solutions, and their higher-order derivatives, of differential equations and it avoids the complexity provided by other numerical approaches. First a new reproducing kernel space is constructed to solve this class of tenth-order linear boundary value problems; then the approximate solutions of such problems are given in the form of series using the present method. Three examples compared with those considered by Siddiqi, Twizell and Akram [S.S. Siddiqi, E.H. Twizell, Spline solutions of linear tenth order boundary value problems, Int. J. Comput. Math. 68 (1998) 345-362; S.S.Siddiqi, G.Akram, Solutions of tenth-order boundary value problems using eleventh degree spline, Applied Mathematics and Computation 185 (1)(2007) 115-127] show that the method developed in this paper is more efficient.

A Novel Channel Estimation using 2-Dimensional Linear Iinterpolation for OFDM MIMO systems (2차원 선형보간법을 이용한 OFDM MIMO 시스템에서의 채널 추정)

  • Oh, Tae Youl;Ahn, Sung Soo;Choi, Seung Won
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.7 no.3
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    • pp.107-113
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    • 2011
  • An OFDMA(Orthogonal Frequency Division Multiple Access) includes a MIMO(Multi-Input Multi-Output) scheme for improving spectral efficiency and data throughput. Recognizing that the performance of MIMO system is heavily dependent upon the accuracy of channel estimation, we propose a novel channel estimation for the MIMO scheme based on OFDMA. Conventional interpolation-based channel estimation suffers from poor estimation error at specific subcarriers. Proposed scheme makes use of a planar interpolation instead of linear interpolation for those subcarriers of bad accuracy. Simulation results show that the proposed scheme improves the performance of MIMO system by improving the accuracy in channel estimation especially for the adverse subcarrier positions. It is observed that the proposed scheme outperforms the conventional method by about 2dB in terms of both mean squared error and overall bit error rate with a reasonable computational complexity.

Efficient detectors for MIMO-OFDM systems under spatial correlation antenna arrays

  • Guerra, David William Marques;Fukuda, Rafael Masashi;Kobayashi, Ricardo Tadashi;Abrao, Taufik
    • ETRI Journal
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    • v.40 no.5
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    • pp.570-581
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    • 2018
  • This work analyzes the performance of implementable detectors for the multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) technique under specific and realistic operation system conditions, including antenna correlation and array configuration. A time-domain channel model was used to evaluate the system performance under realistic communication channel and system scenarios, including different channel correlation, modulation order, and antenna array configurations. Several MIMO-OFDM detectors were analyzed for the purpose of achieving high performance combined with high capacity systems and manageable computational complexity. Numerical Monte Carlo simulations demonstrate the channel selectivity effect, while the impact of the number of antennas, adoption of linear against heuristic-based detection schemes, and the spatial correlation effect under linear and planar antenna arrays are analyzed in the MIMO-OFDM context.

A Frozen Time Receding Horizon Control for a Linear Discrete Time-Varying System (선형 이산 시변시스템을 위한 고정시간 이동구간 제어)

  • Oh, Myung-Hwan;Oh, Jun-Ho
    • Journal of Institute of Control, Robotics and Systems
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    • v.16 no.2
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    • pp.140-144
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    • 2010
  • In the case of a linear time-varying system, it is difficult to apply the conventional stability conditions of RHC (Receding Horizon Control) to real physical systems because of computational complexity comes from time-varying system and backward Riccati equation. Therefore, in this study, a frozen time RHC for a linear discrete time-varying system is proposed. Since the proposed control law is obtained by time-invariant Riccati equation solved by forward iterations at each control time, its stability can be ensured by matrix inequality condition and the stability condition based on horizon for a time-invariant system, and they can be applied to real physical systems effectively in comparison with the conventional RHC.