• Title/Summary/Keyword: State equation

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Stabilization of Co Semigroups in infinite dimensional systems by a compact linear feedback via the steady state Riccati equation

  • Park, Dong-Jo
    • 제어로봇시스템학회:학술대회논문집
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    • 1987.10a
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    • pp.729-733
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    • 1987
  • Stability of Co Semigroups perturbed via the steady state Riccati equation (SSRE) is studied. We consider an infinite dimensional system : .chi. over dot = A.chi. + Bu, in, (A), domain of A, where A is the infinitesimal generator of a Co semigroup [T(t), t.geq.0] in H. If the original Co semigroup [T(t), t.geq.0] has a lower bound : vertical bar T(t).chi. vertical bar .geq. k vertical bar .chi. vertical bar, for all .chi. in H. t.geq. 0 and k>0, then the perturbed Co semigroup via the SSRE, where the feedback operator B is compact, cannot be exponentially stable. Physical interpretation of this result is as follows : in real applications, a finite number of actuators are available, therefore the operator B is compact. When the original system is inherently unstable, that is, has an infinite number of unstable modes, the perturbed system via the SSRE cannot be stable with a uniform decay rate.

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Statistical Measurement of Monsyllable Entropy for Korean Language (한국어 음절의 Entropy에 관한 연구)

  • 이주근;최흥문
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.11 no.3
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    • pp.15-21
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    • 1974
  • The information amount of monosyllables(characters) in Korean language is measured, in order of the following 3 steps. 1) The basic consonants and vowels are partitioned into two steps, 2) These set symbols, C and V, are sequentially combined to obtain the equation which represent the flow state of monosyllables. 3) From the equation, the state graphs can be constructed to examine the proferties of a stochastic process of monosyllables in Korean language. Furthermore, the entropy of Korean language by statistics is measured and compared with that of the western languages. The proposed methods are more definite, systematic, and simpler than the usual methods in examining the nature of information sources.

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Flow/Pressure/Power Control of Hydraulic Pump Utilizing Switching Control Mode (스위칭 제어 모드를 이용한 유압펌프의 유량/압력/동력 제어)

  • Jung, D.S.;Kim, H.E.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.4 no.4
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    • pp.8-14
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    • 2007
  • The electro-hydraulic pump is usually used in testing equipments which require one control function. But until now, it is not applied to industrial equipments which are exposed to severe working environment and require various control functions. This paper proposes a technique which controls continuously flow, pressure and power by utilizing switching control mode. Mathematical model is developed from the continuity equation for the pressurized control volume and the torque balance for the swash plate motion. To simplify the model we make the linear state equation by differentiating the nonlinear model. We analyze the stability and disturbance by using the state variable model. Finally, we review the control performances of flow, pressure and power by tests using PID controller.

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Position Estimation of Chirp Spread Spectrum Node based on Unscented Kalman Filter (Unscented 칼만 필터 기반의 chirp spread spectrum 노드 위치 추정)

  • Cho, Hyeon-Woo;Ban, Sung-Jun;Lee, Young-Hun;Joen, Young-Ju;Kim, Sang-Woo
    • Proceedings of the IEEK Conference
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    • 2009.05a
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    • pp.187-189
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    • 2009
  • Position estimation in indoor is significant problem, because GPS which is usually used for outdoor positioning cannot be utilized to indoor positioning. Sensor network can be a solution for the positioning. Recently, chirp spread spectrum(CSS) specified in IEEE 802.15.4a provides an ability of ranging. Based on the results of the ranging, a position of a CSS node can be calculated by using trilateration. In this case, Kalman filter can be applied to the trilateration because of the measurement noise. In this paper, we apply the unscented Kalman filter for the trilateration. The trilateration can be represented to a nonlinear state space equation, and the unscented Kalman filter is suitable for nonlinear state space equation. Through the experimental results. we show the accuracy of the estimated position.

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Extension of a High Resolution Lagrangian Method to Consider the Real Gas Effect

  • Mazaheri K
    • 한국전산유체공학회:학술대회논문집
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    • 2003.10a
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    • pp.48-49
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    • 2003
  • In the present research a high order Gudonov-type method has been used for the simulation of very high pressure flow fields, as well as the capturing of strong shocks, which usually occur in explosion of high explosives. The treatment strong shocks and the flow field behind the shocks needs a very high resolution scheme. To resolve accurately the shock and the release waves behind the shock the piece­wise parabolic method (PPM) of Colella [1] was utilized in this research. A major problem which encountered in very high pressure problems is the equation of state which differs completely form the ideal-gas equation of state (EOS). Here, the original PPM is extended for real gas effect consideration.

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IMMERSED BOUNDARY METHOD FOR COMPRESSIBLE VISCOUS FLOW AROUND MOVING BODIES (이동하는 물체 주위의 압축성 유동에 대한 가상경계법)

  • Cho, Yong;Chopra, Jogesh;Morris, Philip J.
    • 한국전산유체공학회:학술대회논문집
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    • 2007.10a
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    • pp.200-208
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    • 2007
  • A methodology for the simulation of compressible high Reynolds number flow over rigid and moving bodies on a structured Cartesian grid is described in this paper. The approach is based on a modified version of the Brinkman Penalization method. To avoid oscillations in the vicinity of the body and to simulate shcok-containing flows, a Weighted Essentially Non-Oscillatory scheme is used to discretize the spatial flux derivatives. For high Reynolds number viscous flow, two turbulence models of the two-equation Menter's SST URANS model and a two-equation Detached Eddy Simulation are implemented. Some simple flow examples are given to assess the accuracy of the technique. Finally, a moving grid capability is demonstrated.

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A Study on Hovering Flight Control for a Model Helicopter (모형 헬리콥터 정지비행제어에 관한 연구)

  • 심현철;이은호;이교일
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.6
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    • pp.1399-1411
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    • 1994
  • A model helicopter has more versatile flight capability than the fixed-wing aircraft and it can be used as an unmaned vehicle in hazardous area. A helicopter, similar to other aircrafts, is an unstable, multi-input multi-output nonlinear system exposed to strong disturbance. So it should be controlled by robust control theories that can be applied to multivariable systems. In this study, motion equations of hovering are established, linearized and transformed into a state equation form. Various parameters are measured and calculated in other to obtain the stability derivatives in the state equation. Hovering flight controller is designed using the digital LQG/LTR(Linear Quadratic Gaussian/Loop Transfer Recovery) control theory. The designed controller is tested by the nonlinear simulations and implemented on an IBM-PC/386. Experiments were carried out on a model helicopter attached to the 3-DOF gimbal. The designed controller showed satisfactory hovering capability to maintain the hovering for more than 40 seconds.

Numerical Simulation of a Reciprocating Compressor (왕복동 압축기의 성능해석 시뮬레이션)

  • 김정우;김현진;박희용
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.2
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    • pp.475-483
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    • 1993
  • A computer simulation model of a hermetic reciprocating type of refrigeration compressor has been developed. The compressor simulation model constitutes 6 control volumes, to each of which conservation laws of mass and energy are applied to yield full description of the refrigerant state along its passage. Instead of ideal gas assumption. real gas equation is employed. Some of valve-related input data required for the simulation are acquired from test bench experiments. The refrigerant states such as pressure and temperature, etc., mass flow rates, and valve motions can be predicted by the simulation. The calculated P-V diagram shows a good agreement with experimental result.

A Study on the 3-D Unsteady State Heat Transfer Coupled by Conductive Currents (전기장 변화에 따른 3차원 비정상 상태 열전달 연계 해석에 관한 연구)

  • Kwac, L.K.;Kim, H.G.
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.1
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    • pp.29-34
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    • 2008
  • A modeling technique for the 2-way coupling of heat transfer and conduction currents has been performed to inspire a combined analytical simulation. The 3-D finite element method is used to solve steady conduction currents and heat generation in an aluminum film deposited on a silicon substrate. The model investigates the temperature in the device after the current is applied. The conservation equation of energy, the Maxwell equations for conduction currents, the unsteady state heat transfer equation and the Fourier's law for heat transfer are implemented as a bidirectionally coupled problem. It is found that the strongly coupled temperature and time dependent heat equations give a reasonable results and an explicit solving technique.

Partial Miscibility in Polymer Mixtures from a Viewpoint of the Theory of Flory's Equation of State (Flory의 상태방정식 이론의 관점에서 본 고분자 혼합물에서의 부분혼합도)

  • Jung, Hae-Young
    • Journal of the Korean Chemical Society
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    • v.35 no.6
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    • pp.730-736
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    • 1991
  • In terms of the theory of Flory's Equation of State, the generalized condition for each case of partial miscibilities appearing in the polymer solutions or blends is given. And observing the changes of terms for energies and free volumes in ${\Delta}G_{mix}$ with increasing temperature, their effects on the partial miscibilities are generalized, and the effects of other parameters are also generalized.

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