• Title/Summary/Keyword: non-linear problem

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Analysis of Optimal Buffer Capacities in 3-node Tandem Queues with Blocking (3-노(盧)드 유한 버퍼 일렬대기행렬에서의 최적 버퍼 크기에 대한 분석)

  • Seo, Dong-Won
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2005.05a
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    • pp.881-889
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    • 2005
  • In this study, we consider characteristics of waiting times in single-server 3-node tandem queues with a Poisson arrival process, finite buffers and deterministic or non-overlapping service times at each queue. There are three buffers: one at the first node is infinite and the others are finite. The explicit expressions of waiting times in all areas of the systems, which are driven as functions of finite buffer capacities, show that the sojourn time does not depend on the finite buffer capacities and also allow one to compute and compare characteristics of waiting times at all areas of the system under two blocking policies: communication and manufacturing blocking. As an application of these results, moreover, an optimization problem which determines the smallest buffer capacities satisfying predetermined probabilistic constraints on waiting times is considered. Some numerical examples are also provided.

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Dynamic Analysis of Harmonically Excited Non-Linear System Using Multiple Scales Method

  • Moon, Byung-Young;Kang, Beom-Soo
    • Journal of Mechanical Science and Technology
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    • v.16 no.6
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    • pp.819-828
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    • 2002
  • An analytical method is presented for evaluation of the steady state periodic behavior of nonlinear systems. This method is based on the substructure synthesis formulation and a MS (multiple scales) procedure, which is applied to the analysis of nonlinear responses. The proposed procedure reduces the size of large degrees-of-freedom problem in solving nonlinear equations. Feasibility and advantages of the proposed method are illustrated with the nonlinear rotating machine system as an example of large mechanical structure systems. In addition, its efficiency for nonlinear response prediction will be shown by comparison of other conventional methods.

ANALYSIS OF LOOPED WATER DISTRIBUTION NETWORK

  • Ioan Sarbu
    • Water Engineering Research
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    • v.2 no.3
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    • pp.171-178
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    • 2001
  • There are three methods for analyzing flow and pressure distribution in looped water distribution networks (the loop method, the node method, the element method) taking into consideration hydraulic parameters chosen as unknown. For all these methods the non-linear system of equations can be solved by iterative procedures. The paper presents a different approach to this problem by using the method of variational formulations for hydraulic analysis of water distribution networks. This method has the advantage that it uses a specialized optimization algorithm which minimizes directly an objective multivariable function without constraints, implemented in a computer program. The paper compares developed method to the classic Hardy-Cross method. This shows the good performance of the new method.

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A Mathematical Model of a Central District Heating System for an Urban Residential Community

  • Yoo, Beyong-Woo
    • Journal of Korean Institute of Industrial Engineers
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    • v.4 no.2
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    • pp.97-105
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    • 1978
  • A mathematical model is developed in order to describe the network configuration and heating distribution to a Central District Heating System for an Urban Residential Community. The purpose of using this model is to optimize operating costs and to distribute heat to the Residential Community efficiently. In particular, because of the inherent nonlinearity and dual optimization of the problem a dyamic programming approach is taken. It is turned out that the optimal cost of the system is a strong non-linear function of the network. In particular, it is found that increasing N, the number of houses, may not necessarily imply increased costs. It is felt that past failure of producing economical systems may be due to the improper attention given to the network.

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A Study on the Analysis of Harmonics Reduction Effects Using Single-tuned Filters In a Power System Included Power Converters (전력변환장치를 포함한 전력시스템에서 동조 필터를 이용한 고조파 저감 효과의 분석에 관한 연구)

  • 최홍규;김경철;강태은;전기원
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.14 no.3
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    • pp.81-87
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    • 2000
  • The increasing use of non-linear loads such as power electronics draw highly distorted currents from the utility system. High harmonics currents and voltages will cause equipment damage and disturb the plant operation. The common solution to harmonics problem is to use harmonics filters. In this paper simulation results used the EDSA harmonics analysis program verifying the effects of the single-tuned filter for harmonic elimination are presented.

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A Heuristic Approach for Arrangement of Footwear Boxes to Maximize Space Utilization and Related Business Issues

  • Das Prasun
    • Management Science and Financial Engineering
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    • v.11 no.2
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    • pp.61-84
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    • 2005
  • This paper considers a special case of the two-dimensional bin-packing problem for identical items. The objective of this work is to maximize the space utilization. The main contribution of the paper is to suggest a new heuristic algorithm keeping in view the existing complexity of racking system for the footwear boxes in the compartments of different sizes for a warehouse. The results show that a significant improvement can be obtained. An economic choice of compartments is also estimated using the criteria for maximizing space utilization. A non-linear mathematical model was presented based on the constraints of racking dynamics.

Limit analysis of plates-a finite element formulation

  • Capsoni, Antonio;Corradi, Leone
    • Structural Engineering and Mechanics
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    • v.8 no.4
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    • pp.325-341
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    • 1999
  • A procedure for the computation of the load carrying capacity of perfectly plastic plates in bending is presented. The approach, based on the kinematic theorem of limit analysis, requires the evaluation of the minimum of a convex, but non-smooth, function under linear equality constraints. A systematic solution procedure is devised, which detects and eliminates the finite elements which are predicted as rigid in the collapse mechanism, thus reducing the problem to the search for the minimum of a smooth and essentially unconstrained function of nodal velocities. Both Kirchhoff and Mindlin plate models are considered. The effectiveness of the approach is illustrated by means of some examples.

The refined theory of 2D quasicrystal deep beams based on elasticity of quasicrystals

  • Gao, Yang;Yu, Lian-Ying;Yang, Lian-Zhi;Zhang, Liang-Liang
    • Structural Engineering and Mechanics
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    • v.53 no.3
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    • pp.411-427
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    • 2015
  • Based on linear elastic theory of quasicrystals, various equations and solutions for quasicrystal beams are deduced systematically and directly from plane problem of two-dimensional quasicrystals. Without employing ad hoc stress or deformation assumptions, the refined theory of beams is explicitly established from the general solution of quasicrystals and the Lur'e symbolic method. In the case of homogeneous boundary conditions, the exact equations and exact solutions for beams are derived, which consist of the fourth-order part and transcendental part. In the case of non-homogeneous boundary conditions, the exact governing differential equations and solutions under normal loadings only and shear loadings only are derived directly from the refined beam theory, respectively. In two illustrative examples of quasicrystal beams, it is shown that the exact or accurate analytical solutions can be obtained in use of the refined theory.

Mesoscopic study on historic masonry

  • Sejnoha, J.;Sejnoha, M.;Zeman, J.;Sykora, J.;Vorel, J.
    • Structural Engineering and Mechanics
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    • v.30 no.1
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    • pp.99-117
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    • 2008
  • This paper presents a comprehensive approach to the evaluation of macroscopic material parameters for natural stone and quarry masonry. To that end, a reliable non-linear material model on a meso-scale is developed to cover the random arrangement of stone blocks and quasi-brittle behaviour of both basic components, as well as the impaired cohesion and tensile strength on the interface between the blocks and mortar joints. The paper thus interrelates the following three problems: (i) definition of a suitable periodic unit cell (PUC) representing a particular masonry structure; (ii) derivation of material parameters of individual constituents either experimentally or running a mixed numerical-experimental problem; (iii) assessment of the macroscopic material parameters including the tensile and compressive strengths and fracture energy.

Buckling characteristics and static studies of multilayered magneto-electro-elastic plate

  • Kiran, M.C.;Kattimani, S.C.
    • Structural Engineering and Mechanics
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    • v.64 no.6
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    • pp.751-763
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    • 2017
  • This article deals with the buckling behaviour of multilayered magneto-electro-elastic (MEE) plate subjected to uniaxial and biaxial compressive (in-plane) loads. The constitutive equations of MEE material are used to derive a finite element (FE) formulation involving the coupling between electric, magnetic and elastic fields. The displacement field corresponding to first order shear deformation theory (FSDT) has been employed. The in-plane stress distribution within the MEE plate existing due to the enacted force is considered to be equivalent to the applied in-plane compressive load in the pre-buckling range. The same stress distribution is used to derive the potential energy functional. The non-dimensional critical buckling load is accomplished from the solution of allied linear eigenvalue problem. Influence of stacking sequence, span to thickness ratio, aspect ratio, load factor and boundary condition on critical buckling load and their corresponding mode shape is investigated. In addition, static deflection of MEE plate under the sinusoidal and the uniformly distributed load has been studied for different stacking sequences and boundary conditions.