• Title/Summary/Keyword: state-delay

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Linear quadratic control problem of delay differential equation

  • Shim, Jaedong
    • 제어로봇시스템학회:학술대회논문집
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    • 1992.10b
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    • pp.208-213
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    • 1992
  • In this paper we are concerned with optimal control problems whose costs am quadratic and whose states are governed by linear delay equations and general boundary conditions. The basic new idea of this paper is to Introduce a new class of linear operators in such a way that the state equation subject to a starting function can be viewed as an inhomogeneous boundary value problem in the new linear operator equation. In this way we avoid the usual semigroup theory treatment to the problem and use only linear operator theory.

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The Characterization of Optimal Control Using Delay Differential Operator

  • Shim, Jaedong
    • Journal of the Chungcheong Mathematical Society
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    • v.7 no.1
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    • pp.123-139
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    • 1994
  • In this paper we are concerned with optimal control problems whose costs are quadratic and whose states are governed by linear delay differential equations and general boundary conditions. The basic new idea of this paper is to introduce a new class of linear operators in such a way that the state equation subject to a starting function can be viewed as an inhomogeneous boundary value problem in the new linear operator equation. In this way we avoid the usual semigroup theory treatment to the problem and use only linear operator theory.

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Detection of Delay Attack in IoT Automation System (IoT 자동화 시스템의 지연 공격 탐지)

  • Youngduk Kim;Wonsuk Choi;Dong hoon Lee
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.33 no.5
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    • pp.787-799
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    • 2023
  • As IoT devices are widely used at home, IoT automation system that is integrate IoT devices for users' demand are gaining populrity. There is automation rule in IoT automation system that is collecting event and command action. But attacker delay the packet and make time that real state is inconsistent with state recongnized by the system. During the time, the system does not work correctly by predefined automation rule. There is proposed some detection method for delay attack, they have limitations for application to IoT systems that are sensitive to traffic volume and battery consumption. This paper proposes a practical packet delay attack detection technique that can be applied to IoT systems. The proposal scheme in this paper can recognize that, for example, when a sensor transmits an message, an broadcast packet notifying the transmission of a message is sent to the Server recognized that event has occurred. For evaluation purposes, an IoT system implemented using Raspberry Pi was configured, and it was demonstrated that the system can detect packet delay attacks within an average of 2.2 sec. The experimental results showed a power consumption Overhead of an average of 2.5 mA per second and a traffic Overhead of 15%. We demonstrate that our method can detect delay attack efficiently compared to preciously proposed method.

A Time Delay-Based Gain Scheduled Control and It's Application to Electromagnetic Suspension System (시간지연 이득계획제어와 자기부상시스템에의 응용)

  • Hong Ho-Kyung;Jo Jeong-Min;Cho Heung-Jae
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.54 no.12
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    • pp.569-575
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    • 2005
  • This paper proposes a gain scheduled control technique using time-delay for the nonlinear system with plant uncertainties and unexpected disturbances. The time delay-based gain scheduled control depends on a direct estimation of a function representing the effect of uncertainties. The information from the estimation is used to cancel the unknown dynamics and the unexpected disturbances simultaneously. The proposed estimation scheme with a finite convergence time is formulated in order to estimate the unknown scheduling variable variation. In other words, the time delay-based gain scheduled control uses the past observation of the system's response and the control input to directly modify the control actions rather than to adjust the controller gains or to identify system parameters. It has a simple structure so as to minimize the computational burden. The benefits of this proposed scheme are demonstrated in the simulation of an electromagnetic suspension system with plant uncertainties and external disturbances, and the proposed controller is compared with the conventional state feedback controller.

Adaptive Cross-Layer Resource Optimization in Heterogeneous Wireless Networks with Multi-Homing User Equipments

  • Wu, Weihua;Yang, Qinghai;Li, Bingbing;Kwak, Kyung Sup
    • Journal of Communications and Networks
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    • v.18 no.5
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    • pp.784-795
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    • 2016
  • In this paper, we investigate the resource allocation problem in time-varying heterogeneous wireless networks (HetNet) with multi-homing user equipments (UE). The stochastic optimization model is employed to maximize the network utility, which is defined as the difference between the HetNet's throughput and the total energy consumption cost. In harmony with the hierarchical architecture of HetNet, the problem of stochastic optimization of resource allocation is decomposed into two subproblems by the Lyapunov optimization theory, associated with the flow control in transport layer and the power allocation in physical (PHY) layer, respectively. For avoiding the signaling overhead, outdated dynamic information, and scalability issues, the distributed resource allocation method is developed for solving the two subproblems based on the primal-dual decomposition theory. After that, the adaptive resource allocation algorithm is developed to accommodate the timevarying wireless network only according to the current network state information, i.e. the queue state information (QSI) at radio access networks (RAN) and the channel state information (CSI) of RANs-UE links. The tradeoff between network utility and delay is derived, where the increase of delay is approximately linear in V and the increase of network utility is at the speed of 1/V with a control parameter V. Extensive simulations are presented to show the effectiveness of our proposed scheme.

Ignition Characteristics of JP-7 as a Scramjet Fuel (스크램제트 연료로써 JP-7 의 점화 특성)

  • Choi Jeong-Yeol;Puri Puneesh;Ma Fuhua;Yang Vigor
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • v.y2005m4
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    • pp.377-380
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    • 2005
  • A study of ignition characteristics of cracked JP-7 fuel with both oxygen and air has been conducted over a wide range of pressures (1-20 atm), temperatures (1200-2000 K), and equivalence ratios (0.5-1.5). Correlations of ignition delay, of the form, τ=Aexp(E/RT)[F]a[O2]b are established using the Chemkin-II package and least square analysis. The effect of C3 hydrocarbons in cracked JP-7 fuel is examined by comparing the ignition delays for two different cracked compositions. A comparison for ignition delay is also made with the experimental results obtained by injecting liquid JP-7 fuel in air using a shock tube apparatus.

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Simplified Controller Design Method for Digitally Controlled LCL-Type PWM Converter with Multi-resonant Quasi-PR Controller and Capacitor-Current-Feedback Active Damping

  • Lyu, Yongcan;Lin, Hua
    • Journal of Power Electronics
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    • v.14 no.6
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    • pp.1322-1333
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    • 2014
  • To track the sinusoidal current under stationary frame and suppress the effects of low-order grid harmonics, the multi-resonant quasi-proportional plus resonant (PR) controller has been extensively used for digitally controlled LCL-type pulse-width modulation (PWM) converters with capacitor-current-feedback active damping. However, designing the controller is difficult because of its high order and large number of parameters. Moreover, the computation and PWM delays of the digitally controlled system significantly affect damping performance. In this study, the delay effect is analyzed by using the Nyquist diagrams and the system stability constraint condition can be obtained based on the Nyquist stability criterion. Moreover, impact analysis of the control parameters on the current loop performance, that is, steady-state error and stability margin, identifies that different control parameters play different decisive roles in current loop performance. Based on the analysis, a simplified controller design method based on the system specifications is proposed. Following the method, two design examples are given, and the experimental results verify the practicability and feasibility of the proposed design method.

An Efficient Downlink Scheduling Scheme Using Prediction of Channel State in an OFDMA-TDD System (OFDMA-TDD 시스템에서 채널상태 예측을 이용한 효율적인 하향링크 스케줄링 기법)

  • Kim Se-Jin;Won Jeong-Jae;Lee Hyong-Woo;Cho Choong-Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.5A
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    • pp.451-458
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    • 2006
  • In this paper, we propose a novel scheduling algorithm for downlink transmission which utilizes scarce wireless resource efficiently in an Orthogonal Frequency Division Multiple Access/Time Division Duplex system. Scheduling schemes which exploit channel information between a Base Station and terminals have been proposed recently for improved performance. Time series analysis is used to estimate the channel state of mobile terminals. The predicted information is then used for prioritized scheduling of downlink transmissions for improved throughput, delay and jitter performance. Through simulation, we show that the total throughput and mean delay of the proposed scheduling algorithm are improved compared with those of the Proportional Fairness and Maximum Carrier to Interference Ratio schemes.

Observer Design for A Class of UncertainState-Delayed Nonlinear Systems

  • Lu Junwei;Feng Chunmei;Xu Shengyuan;Chu Yuming
    • International Journal of Control, Automation, and Systems
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    • v.4 no.4
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    • pp.448-455
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    • 2006
  • This paper deals with the observer design problem for a class of state-delayed nonlinear systems with or without time-varying norm-bounded parameter uncertainty. The nonlinearities under consideration are assumed to satisfy the global Lipschitz conditions and appear in both the state and measured output equations. The problem we address is the design of a nonlinear observer such that the resulting error system is globally asymptotically stable. For the case when there is no parameter uncertainty, a sufficient condition for the solvability of this problem is derived in terms of linear matrix inequalities and the explicit formula of a desired observer is given. Based on this, the robust observer design problem for the case when parameter uncertainties appear is considered and the solvability condition is also given. Both of the solvability conditions obtained in this paper are delay-dependent. A numerical example is provided to demonstrate the applicability of the proposed approach.

New Reference Generation for a Single-Phase Active Power Filter to Improve Steady State Performance

  • Lee, Ji-Heon;Jeong, Jong-Kyou;Han, Byung-Moon;Bae, Byung-Yeol
    • Journal of Power Electronics
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    • v.10 no.4
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    • pp.412-418
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    • 2010
  • This paper proposes a new algorithm to generate a reference signal for an active power filter using a sliding-window FFT operation to improve the steady-state performance of the active power filter. In the proposed algorithm the sliding-window FFT operation is applied to the load current to generate the reference value for the compensating current. The magnitude and phase-angle for each order of harmonics are respectively averaged for 14 periods. Furthermore, the phase-angle delay for each order of harmonics passing through the controller is corrected in advance to improve the compensation performance. The steady-state and transient performance of the proposed algorithm was verified through computer simulations and experimental work with a hardware prototype. A single-phase active power filter with the proposed algorithm can offer a reduction in THD from 75% to 4% when it is applied to a non-linear load composed of a diode bridge and a RC circuit. The active power filter with the proposed reference generation method shows accurate harmonic compensation performance compared with previously developed methods, in which the THD of source current is higher than 5%.