• Title, Summary, Keyword: Order reduction

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COMPARISON OF SOME ORDER_REDUCTION METHODS FOR LINEAR SYSTEMS

  • Lee, K.
    • Proceedings of the KIEE Conference
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    • pp.299-302
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    • 1993
  • Some well known order reduction methods are briefly described and a nev order reduction technique is introduced. A comparison of the various classes of order reduction approaches are indicated. Furthermore, the question is raised how order reduction should be executed with respect to controller design. Finally, by means of an example, results of the discussed approaches are compared.

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Transient response analysis by model order reduction of a Mokpo-Jeju submerged floating tunnel under seismic excitations

  • Han, Jeong Sam;Won, Boreum;Park, Woo-Sun;Ko, Jin Hwan
    • Structural Engineering and Mechanics
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    • v.57 no.5
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    • pp.921-936
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    • 2016
  • In this study, a model order reduction technique is applied to solve the transient responses of submerged floating tunnel (SFT) from Mokpo to Jeju under seismic excitations. Because the SFT is a very long structure as well as a transient response analysis requires large amount of computational resources, the model order reduction is mandatory in the design stage of the SFT. Thus, we apply a model order reduction based on Krylov subspace to the simplified finite element model of the SFT. The responses of the reduced order model are compared with those of the full order model and also are verified by referring a previous work. In conclusion, the computational resources are dramatically reduced with an acceptable accuracy by using the model order reduction, which eventually is useful for designing the full-scale model of SFTs.

SYNCHRONIZING INDIVIDUALLY OPTIMAL CYCLE TIMES ACROSS MULITI-BUYERS AND MULTI-PRODUCTS

  • Lee, Chang-Hwan
    • Management Science and Financial Engineering
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    • v.4 no.2
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    • pp.15-42
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    • 1998
  • A joint problem of order delivery, setup reduction, and cost-sharing in a two-echelon inventory system in which a vendor supplies multiple products to a group of buyers is studied here. The basic premise is that buyers have independently implemented setup reduction programs to acquire benefits from small order sizes. Doing so, however, causes the buyers' individually optimal order cycles to be differ from that of the vendor. In conjunction with this, two models are considered. In the first model, a multi-buyers single product situation is considered in which the vendor implements a joint supply cycle policy. However, buyers, as the dominant party, insist after implementing the individually optimal setup reduction that the vendor accept their individually optimal order schedules. In the second model. a multi-products, single buyer situation is considered in which the buyer implements a joint order policy. Here, the vendor, as the dominant party, refuses to cooperate fully with the buyer's individually reduced joint order schedule, and designs his own individually optimal setup reduction mix for each product under a given budget constraint. This led to a study of an integrated Setup Reduction/Break-even Pricing Policy for each situation to eliminate mismatches in individually optimal cycle times.

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An efficient parallel solution algorithm on the linear second-order partial differential equations with large sparse matrix being based on the block cyclic reduction technique (Block Cyclic Reduction 기법에 의한 대형 Sparse Matrix 선형 2계편미분방정식의 효율적인 병렬 해 알고리즘)

  • 이병홍;김정선
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.15 no.7
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    • pp.553-564
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    • 1990
  • The co-efficient matrix of linear second-order partial differential equations in the general form is partitioned with (n-1)x(n-1) submartices and is transformed into the block tridiagonal system. Then the cyclic odd-even reduction technique is applied to this system with the large-grain data granularity and the block cyclic reduction algorithm to solve unknown vectors of this system is created. But this block cyclic reduction technique is not suitable for the parallel processing system because of its parallelism chanigng at every computing stages. So a new algorithm for solving linear second-order partical differential equations is presentes by the block cyclic reduction technique which is modified in order to keep its parallelism constant, and to reduce gteatly its execution time. Both of these algoriths are compared and studied.

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MPV-Reduction of C=O bond with Al-substituted-dialkylalan; A Theoretical Study on Relative Reactivity of Various Carbonyl Substrates

  • Nahm, Keepyung
    • Bulletin of the Korean Chemical Society
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    • v.35 no.2
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    • pp.546-550
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    • 2014
  • Relative reactivity of various carbonyl and acid derivatives in MPV-type (Meerwein-Ponndorf-Verley) reduction with an DIBAL(F) model has been studied via DFT and MP2 methods. Free energies of initial adduct formation (-Gadd) of DIBAL(F) model and carbonyls are in the order of amide < ester < aldehyde < ketone < acid chloride; in the alan-amide adduct, the developed positive charge at carbonyl carbon is expected to be stabilized by amide resonance, but in the acid chloride adduct it is destabilized by inductive effect of chloride. However the TS barrier energies (${\Delta}G_{TS}$) for the MPV-type hydride reduction of the carbonyl adducts are in the order of aldehyde < ketone < acid chloride << ester < amide; presumably decreasing order of electrophilicity of carbonyl carbon at adducts, which is well correlated with experimental data. It is noted that the relative reactivity of carbonyl derivatives in MPV-type reduction with DIBAL(X) is not governed by the alan-adduct formation energies, but follows the order of electrophilicity of carbonyl carbon of transition states.

Model order reduction with pass band error reduction in frequency domain (주파수 영역에서 통과대역 오차 감소를 갖는 모델 저차수화)

  • 김정화;정찬수
    • 제어로봇시스템학회:학술대회논문집
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    • pp.1219-1219
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    • 1991
  • This paper proposes the model order reduction with pass band error reduction in the frequency domain of discrete time linear systems. The algorithm is the new method of reduced order model which reduces passband error by changing controllability and observability gramian used with weighted functions. A numerical example shows that this algorithm has lower passband error than balanced w&l and weighted function characteristics in frequency domain.

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Dynamic Analysis of Rotating Bodies Using Model Order Reduction (모델차수축소기법을 이용한 회전체의 동해석)

  • Han, Jeong-Sam
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.443-444
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    • 2011
  • This paper discusses a model order reduction for large order rotor dynamics systems results from the finite element discretization. Typical rotor systems consist of a rotor, built-on parts, and a support system, and require prudent consideration in their dynamic analysis models because they include unsymmetric stiffness, localized nonproportional damping and frequency dependent gyroscopic effects. When the finite element model has a very large number of degrees of freedom because of complex geometry, repeated dynamic analyses to investigate the critical speeds, stability, and unbalanced response are computationally very expensive to finish within a practical design cycle. In this paper, the Krylov-based model order reduction via moment matching significantly speeds up the dynamic analyses necessary to check eigenvalues and critical speeds of a Nelson-Vaugh rotor system. With this approach the dynamic simulation is efficiently repeated via a reduced system by changing a running rotational speed because it can be preserved as a parameter in the process of model reduction. The Campbell diagram by the reduced system shows very good agreement with that of the original system. A 3-D finite element model of the Nelson-Vaugh rotor system is taken as a numerical example to demonstrate the advantages of this model reduction for rotor dynamic simulation.

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Designing a Coordinated Setup Cost Reduction Program of a Supply Chain

  • Lee, Chang-Hwan;Pae, Jae-H.
    • Management Science and Financial Engineering
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    • v.13 no.2
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    • pp.117-139
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    • 2007
  • This paper contributes by incorporating works addressing supply chain coordination and investing in setup reduction program. Consider a two-echelon, EOQ-like inventory system consisting of a supplier and a buyer. We assume that both the supplier and the buyer can invest in setup cost reduction programs in order to benefit from small order sizes. However, the costs of investing in setup cost reduction programs are different for the two parties, leading to mismatches in individually optimal setup costs and order cycle times. We propose a supply chain coordination contract that makes use of quantity discount as an incentive transfer scheme for supply chain coordination.

Design of PID Controller to Ensure Specified Phase margin and Iso-damping property Using Reduction Model (축소 모델을 이용한 위상여유와 등 제동 특성을 만족하는 PID 제어기 설계)

  • Cho, Joon-Ho;Hwang, Hyung-Soo
    • Proceedings of the KIEE Conference
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    • pp.113-118
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    • 2007
  • In this paper, a new method is proposed for robust proportional- integral - derivative (PID) control that is to ensure specified phase margin and iso - damping property using reduction model. This method is based on the second order plus dead time(SOPDT) reduction model of the high order model. Reduction model used to ensure iso-damping property in the feature frequency. Simulation results gives proof of effectiveness of proposed method.

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Frequency-Domain Balanced Stochastic Truncation for Continuous and Discrete Time Systems

  • Shaker, Hamid Reza
    • International Journal of Control, Automation, and Systems
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    • v.6 no.2
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    • pp.180-185
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    • 2008
  • A new method for relative error continuous and discrete time model order reduction is proposed. The reduction technique is based on two recently developed methods, namely frequency domain balanced truncation within a frequency bound and inner-outer factorization techniques. The proposed method is of interest for practical model order reduction because in this context it shows to keep the accuracy of the approximation as high as possible without sacrificing the computational efficiency. Numerical results show the accuracy and efficiency enhancement of the method.