• Title/Summary/Keyword: distributed feedback

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Opportunistic Spectrum Access with Discrete Feedback in Unknown and Dynamic Environment:A Multi-agent Learning Approach

  • Gao, Zhan;Chen, Junhong;Xu, Yuhua
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.9 no.10
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    • pp.3867-3886
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    • 2015
  • This article investigates the problem of opportunistic spectrum access in dynamic environment, in which the signal-to-noise ratio (SNR) is time-varying. Different from existing work on continuous feedback, we consider more practical scenarios in which the transmitter receives an Acknowledgment (ACK) if the received SNR is larger than the required threshold, and otherwise a Non-Acknowledgment (NACK). That is, the feedback is discrete. Several applications with different threshold values are also considered in this work. The channel selection problem is formulated as a non-cooperative game, and subsequently it is proved to be a potential game, which has at least one pure strategy Nash equilibrium. Following this, a multi-agent Q-learning algorithm is proposed to converge to Nash equilibria of the game. Furthermore, opportunistic spectrum access with multiple discrete feedbacks is also investigated. Finally, the simulation results verify that the proposed multi-agent Q-learning algorithm is applicable to both situations with binary feedback and multiple discrete feedbacks.

Design of Fuzzy Output Feedback Controller for The Nonlinear Systems with Time -Delay

  • Shin, Hyun-Seok;Kim, Eun-Tai;Park, Mignon
    • Journal of the Korean Institute of Intelligent Systems
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    • v.12 no.6
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    • pp.559-564
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    • 2002
  • This Paper Proposes a design method of a fuzzy output feedback controller for the nonlinear systems with the unknown time- delay. Recently, Cao et ai. proposed a stabilization method for the nonlinear time-delay systems using a fuzzy controller when the time-delay is known. However, the time-delay is likely to be unknown in practical. We represent the nonlinear systems with the unknown time-delay by Takagi-Sugeno (T-5) fuzzy model and design the fuzzy observer and the parallel distributed compensation (PDC) law based on this observer. By applying Lyapunov-Krasovskii theorem to the closed-loop system, the sufficient condition for the asymptotic stability of the equilibrium Point is derived and converted into the linear matrix inequality (LMI) Problem.

Implementing Balanced Scorecard with System Dynamics Approach

  • Yoon, Joseph Y. K.
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2000.04a
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    • pp.330-336
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    • 2000
  • This paper discusses the potential of system dynamics modelling to support balanced scorecard. The balanced scorecard is a conceptual framework for translating an organisation's strategy into a set of performance indicators. These performance indicators are distributed across the 'classic'model's four perspective: Customers, Internal Business Processes, Financial, and Learning and Growth. This balanced scorecard, whilst having significant strength, suffers from the limitation of all performance indicator systems, namely that the interrelationships between indicators are overlooked and there is no way of taking into account the impact of delayed feedback which flows from introduction of new policy and legislative changes. System Dynamics is a methodology for understanding complex problems where there is dynamic behaviour and where feedback impacts significantly on system outcomes. System dynamics provides a rigorous basis for qualitative testing of the effects of performance indicators in complex environments such as health or social security. This can be supplemented with quantitative system dynamics simulation tools that further test the validity of indicators and the business rules implicit in them. System dynamics modelling has an important role to play in extending feedback cycle in performance measurements to a full systems approach.

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Fuzzy Controller Design for Nonlinear Systems Using Optimal Pole-Placement Schemes (최적 극점 배치 기법을 이용한 비선형 시스템의 퍼지 제어기의 설계)

  • Lee, Nam-Su;Joo, Young-Hoon;Kim, Kwang-Bae
    • Proceedings of the KIEE Conference
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    • 1999.07b
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    • pp.510-512
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    • 1999
  • In this paper, we present a method for the analysis and design of fuzzy controller for nonlinear systems. In the design procedure, we represent the dynamics of nonlinear systems using a Takagi-Sugeno fuzzy model and formulate the controller rules, which shares the same fuzzy sets with the fuzzy system, using parallel distributed compensation method. Then, after the feedback gain of each local state feedback controller is obtained using the existing optimal pole-placement scheme, we construct an overall fuzzy logic controller by blending all local state feedback controller. Finally, the effectiveness and feasibility of the proposed fuzzy-model-based controller design method has been evaluated through an inverted pendulum system.

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Microassembly System for the assembly of photonic components (광 부품 조립을 위한 마이크로 조립 시스템)

  • 강현재;김상민;남궁영우;김병규
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.241-245
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    • 2003
  • In this paper, a microassembly system based on hybrid manipulation schemes is proposed and applied to the assembly of a photonic component. In order to achieve both high precision and dexterity in microassembly, we propose a hybrid microassembly system with sensory feedbacks of vision and force. This system consists of the distributed 6-DOF micromanipulation units, the stereo microscope, and haptic interface for the force feedback-based microassembly. A hybrid assembly method, which combines the vision-based microassembly and the scaled teleoperated microassembly with force feedback, is proposed. The feasibility of the proposed method is investigated via experimental studies for assembling micro opto-electrical components. Experimental results show that the hybrid microassembly system is feasible for applications to the assembly of photonic components in the commercial market with better flexibility and efficiency.

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Thermally-Induced Vibration Control of Rotating Composite Thin-Walled Blade (회전하는 복합재 블레이드의 열진동 해석 및 제어)

  • Jung, Hoe-Do;Na, Sung-Soo;Kwak, Mun-Kyu;Heo, Seok
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.1696-1701
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    • 2003
  • This paper deals with a vibration control analysis of a rotating composite blade, modeled as a tapered thinwalled beam induced by heat flux. The displayed results reveal that the thermally induced vibration yields a detrimental repercussions upon their dynamic responses. The blade consists of host graphite epoxy laminate with surface and spanwise distributed transversely isotropic (PZT-4) sensors and actuators. The controller is implemented via the negative velocity and displacement feedback control methodology, which prove to overcome the deleterious effect associated with the thermally induced vibration. The structure is modeled as a composite thin-walled beam incorporating a number of nonclassical features such as transverse shear, secondary warping, anisotropy of constituent materials, and rotary inertias.

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ISM Application Tool, A Contribution to Address the Barrier of Information Security Management System Implementation

  • Chandra, Nungky Awang;Sadikin, Mujiono
    • Journal of information and communication convergence engineering
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    • v.18 no.1
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    • pp.39-48
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    • 2020
  • Information-security management systems (ISMSs) are becoming very important, even for micro, small, and medium enterprises (MSMEs). However, implementing an ISMS is not an easy task. Many obstacles must be overcome, e.g., complexity, document tracking, competency management, and even changing cultures. The objective of our study is to provide ISMS application tools, based on ISO 27001:2013 ISM frameworks. The application was developed on the Odoo Open Enterprise Resource Planning platform. To validate its feasibility for future improvement, the application was implemented by an MSME company. For this implementation, information-security-related users gave their feedback through a questionnaire. The distributed feedback questionnaire consists of nine assessment parameters, covering topics from the application's technical aspects to users' experiences. Based on the questionnaire feedback, all users of the application were satisfied with its performance.

An Alternative Zero Voltage Switching Method of Boost Rectifier in Power Factor Correction Rectifier/Regulator System using DC Linked Energy Feedback Circuit

  • Roh, Chung-Wook;Kim, Bok-Man;Moon, Gun-Woo;Youn, Myung-Joong
    • Proceedings of the KIPE Conference
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    • 1998.10a
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    • pp.270-275
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    • 1998
  • A new single phase power factor correction rectifier/regulator with dc linked energy feedback circuit is proposed, which is capable of achieving the zero voltage switching (ZVS) of a boost rectifier stage without any auxiliary switch. The performance of the proposed rectifier/regulator is demonstrated through a 200W, 90 KHz prototype. This proposed rectifier/regulator with dc linked energy feedback circuit is particularly suited for distributed power system applications

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Fuzzy control for geometrically nonlinear vibration of piezoelectric flexible plates

  • Xu, Yalan;Chen, Jianjun
    • Structural Engineering and Mechanics
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    • v.43 no.2
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    • pp.163-177
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    • 2012
  • This paper presents a LMI(linear matrix inequality)-based fuzzy approach of modeling and active vibration control of geometrically nonlinear flexible plates with piezoelectric materials as actuators and sensors. The large-amplitude vibration characteristics and dynamic partial differential equation of a piezoelectric flexible rectangular thin plate structure are obtained by using generalized Fourier series and numerical integral. Takagi-Sugeno (T-S) fuzzy model is employed to approximate the nonlinear structural system, which combines the fuzzy inference rule with the local linear state space model. A robust fuzzy dynamic output feedback control law based on the T-S fuzzy model is designed by the parallel distributed compensation (PDC) technique, and stability analysis and disturbance rejection problems are guaranteed by LMI method. The simulation result shows that the fuzzy dynamic output feedback controller based on a two-rule T-S fuzzy model performs well, and the vibration of plate structure with geometrical nonlinearity is suppressed, which is less complex in computation and can be practically implemented.

Packet Loss Patterns Adaptive Feedback Scheduling for Reliable Multicast

  • Baek, Jin-Suk;Kim, Cheon-Shik;Hong, You-Sik
    • Journal of Ubiquitous Convergence Technology
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    • v.1 no.1
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    • pp.28-34
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    • 2007
  • Tree-based reliable multicast protocols provide scalability by distributing error-recovery tasks among several repair nodes. These repair nodes perform local error recovery for their receiver nodes using the data stored in their buffers. We propose a packet loss patterns adaptive feedback scheduling scheme to manage these buffers in an efficient manner. Under our scheme, receiver nodes send NAKs to repair nodes to request packet retransmissions only when the packet losses are independent events from other nodes. At dynamic and infrequent intervals, they also send ACKs to indicate which packets can be safely discarded from the repair node's buffer. Our scheme reduces delay in error recovery because the requested packets are almost always available in the repair node's buffers. It also reduces the repair node's workload because (a) each receiver node sends infrequent ACKs with non-fixed intervals and (b) their sending times are fairly distributed among all the receiver nodes.

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