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  • Title/Summary/Keyword: state-delay

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S-Band Solid State Power Oscillator for RF Heating (RF 가열용 S-대역 반도체 전력 발진기)

  • Jang, Kwang-Ho;Kim, Bo-Ki;Choi, Jin-Joo;Choi, Heung-Sik;Sim, Sung-Hun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.29 no.2
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    • pp.99-108
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    • 2018
  • This paper presents a design study of a solid state power oscillator to replace the conventional magnetron. The operational conditions of a single-stage 300 W LDMOS power amplifier were fully characterized. The power module consisted of two amplifiers connected in parallel. A delay-line feedback loop was designed for self-oscillation. A phase shifter was inserted in the delay-line feedback loop for adjusting the round-trip phase. Experiments performed using the power oscillator showed an output power of 800 W and a DC-RF conversion efficiency of 58 % at 2.327 GHz. The measured results were in good agreement with those predicted by numerical simulations.

Robust Deadbeat Current Control Method for Three-Phase Voltage-Source Active Power Filter

  • Nishida, Katsumi;Ahmed, Tarek;Nakaoka, Mutsuo
    • Journal of Power Electronics
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    • v.4 no.2
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    • pp.102-111
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    • 2004
  • This paper is concerned with a deadbeat current control implementation of shunt-type three-phase active power filter (APF). Although the one-dimensional deadbeat control method can attain time-optimal response of APF compensating current, one sampling period is actually required fur its settling time. This delay is a serious drawback for this control technique. To cancel such a delay and one more delay caused by DSP execution time, the desired APF compensating current has to be predicted two sampling periods ahead. Therefore an adaptive predictor is adopted for the purpose of both predicting the control error of two sampling periods ahead and bringing the robustness to the deadbeat current control system. By adding the adaptive predictor output as an adjustment term to the reference value of half a source voltage period before, settling time is made short in a transient state. On the other hand, in a steady state, THD (total harmonic distortion) of the utility grid side AC source current can be reduced as much as possible, compared to the case that ideal identification of controlled system could be made.

GLOBAL STABILITY OF HIV INFECTION MODELS WITH INTRACELLULAR DELAYS

  • Elaiw, Ahmed;Hassanien, Ismail;Azoz, Shimaa
    • Journal of the Korean Mathematical Society
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    • v.49 no.4
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    • pp.779-794
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    • 2012
  • In this paper, we study the global stability of two mathematical models for human immunodeficiency virus (HIV) infection with intra-cellular delays. The first model is a 5-dimensional nonlinear delay ODEs that describes the interaction of the HIV with two classes of target cells, CD4+ T cells and macrophages taking into account the saturation infection rate. The second model generalizes the first one by assuming that the infection rate is given by Beddington-DeAngelis functional response. Two time delays are used to describe the time periods between viral entry the two classes of target cells and the production of new virus particles. Lyapunov functionals are constructed and LaSalle-type theorem for delay differential equation is used to establish the global asymptotic stability of the uninfected and infected steady states of the HIV infection models. We have proven that if the basic reproduction number R0 is less than unity, then the uninfected steady state is globally asymptotically stable, and if the infected steady state exists, then it is globally asymptotically stable for all time delays.

State feedback controller design for linear multivariable systems with delays (다변수 시간지연 시스템의 상태궤환 제어기 설계)

  • 홍석민;황승구;이상정
    • 제어로봇시스템학회:학술대회논문집
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    • 1992.10a
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    • pp.1040-1044
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    • 1992
  • This paper presents an algebraic approach for finding a dynamic state feedback controller when the linear multi-input system with delays in both state and input is controllable. In the time-delay case, controllability of the system does not always imply that system is cyclizable. Therefore, reduced order augmentation systems which is cyclizable as the time-varying case are considered. It is possible to construct feedback contorl systems by using single-input methods.

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A state estimator design for servo system with delayed input (지연입력을 가진 서보시스템의 상태추정자 설계)

  • Kong, Jeong-Ja;Huh, Uk-Youl;Jeong, Kab-Kyun
    • Proceedings of the KIEE Conference
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    • 1998.07b
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    • pp.537-540
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    • 1998
  • This thesis deals with the design problem of the state estimator for digital servo system. Digital servo system has input time delay, which depends on the size of control algorithm. The delayed input is a factor that brings out the state estimation error. So, in order to reduce this state estimation error of the system, we proposes a state estimator in which the delayed input of the system is considered. At first, a discrete-time state-space model is established accounting for the delayed input. Next, the state estimator is designed based on this model. we employ Kalman filter algorithm in design of the state estimator. The performance of proposed state estimator is exemplified via some simulations and experiment for servo system. And robustness of the proposed estimator to modelling error by variation of the system parameter is also shown in these simulations.

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Optimal Control Policy for Linear-Quadratic Control Problems with Delay and Intermediate State Constraints

  • Chong, Kil-To;Kostyukova, Olga;Kurdina, Mariya
    • International Journal of Control, Automation, and Systems
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    • v.6 no.6
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    • pp.845-858
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    • 2008
  • In this paper, we consider a terminal, linear control system with delay, subject to unknown but bounded disturbances. For this system, we consider the problem of constructing a worst-case optimal feedback control policy, which can be corrected at fixed, intermediate time instants. The policy should guarantee that for all admissible uncertainties the system states are in prescribed neighborhoods of predefined system states, at all fixed, intermediate time instants, and in the neighborhood of a given state at a terminal time instant, and the value of the cost function is the best guaranteed value. Simple explicit rules(which can be easily implemented on-line) for constructing the optimal control policy in the original control problem are derived.

Channel Input-Traffic Control of FH/SSMA Systems with a Centralized Controller (기지국이 있는 주파수 도약 대역확산 통신 시스템에서의 채널 입력 트래픽 제어)

  • 김석찬;김정곤;송익호;김형명
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.21 no.1
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    • pp.175-186
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    • 1996
  • An optimal channel input-traffic control (OCIC) policy is proposed for slotted frequency-hopped spread-spectrum multiple access communication systems. When the number of channel input packets is set to the optimal number, the conditional throughput for the OCIC policy is analyzed. The state transition probability is derived, the steady state performance is analyzed, and the mean pracket delay is obtained. It is shown that the mean packet delay decreases considerably when the priority of transmission is given to backlogged users. The smaller is the number of requency slots, the larger are the differences between the preformance of the OCIC policy and that of the other policies.

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TRAVELING WAVES OF AN SIRS EPIDEMIC MODEL WITH SPATIAL DIFFUSION AND TIME DELAY

  • Du, Yanke;Xu, Rui
    • Journal of applied mathematics & informatics
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    • v.30 no.3_4
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    • pp.635-646
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    • 2012
  • This paper is concerned with an SIRS epidemic model with spatial diffusion and time delay representing the length of the immunity period. By using a new cross iteration scheme and Schauder's fixed point theorem, we reduce the existence of traveling wave solutions to the existence of a pair of upper-lower solutions. By constructing a newfashioned pair of upper-lower solutions, we derive the existence of a traveling wave solution connecting the uninfected steady state and the infected steady state.

A Study on the Impedance Effect of Nonvolatile SNOSEFT EFFPROM Memory Devices (비휘발성 SNOSEFT EFFPROM 기억소자의 임피던스 효과에 관한 연구)

  • 강창수;김동진;김선주;이상배;이성배;서광열
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1995.05a
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    • pp.86-89
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    • 1995
  • In this pacer, The effect of the impedances in SNOSEFT s memory devices has been developed. The effect of source and drain impedances are measuring using the method of the field effect bias resistance in the inner resistance regions of the device structure and external bias resistance. The effect of impedance by source and drain resistance shows according to increasing to the storage of memory charges, shows according to a function of decreasing to the gate voltages, shows the delay of threshold voltages, The delay time of low conductance state and high conductance state by the impedance effect shows 3 [μsec] and 1[μsec] respectively.

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Non-fragile Guaranteed Cost Controller Design for Uncertain Time-delay Systems via Delayed Feedback (지연귀환을 통한 불확실 시간지연 시스템의 비약성 성능보장 제어기 설계)

  • Kwon, Oh-Min;Park, Ju-Hyun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.3
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    • pp.458-465
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    • 2008
  • In this paper, we propose a non-fragile guaranteed cost controller design method for uncertain linear systems with constant delyas in state. The norm bounded and time-varying uncertainties are subjected to system and controller design matrices. A quadratic cost function is considered as the performance measure for the system. Based on the Lyapunov method, an LMI(Linear Matrix Inequality) optimization problem is established to design the controller which uses information of delayed state and minimizes the upper bound of the quadratic cost function for all admissible system uncertainties and controller gain variations. Numerical examples show the effectiveness of the proposed method.