Current Issue : July - September Volume : 2012 Issue Number : 3 Articles : 6 Articles
The decision of call admission becomes an important work owing to the scarce wireless spectrum for wireless cellular networks.\r\nIf there exists adequate information for call admission control (CAC) schemes, the terms of quality of service (QoS), such as call\r\ndropping probability (CDP), call blocking probability (CBP), and system utilization, will be kept in a certain acceptable level.\r\nTherefore, a prediction system which can predict most information, such as system utilization and CDP, in advance with a novel\r\ndata mining technique and a distributed CAC scheme is presented in this paper. Based on the prediction results and the bandwidth\r\nconsumption of adjacent cells, the proposed CAC scheme is able to decide to admit a new call. The throttle flag that can indicate\r\nthe usage of current cell is proposed to prevent the newly admitted call request from being blocked in adjacent cells if handoff is\r\nneeded. The simulation results show that the proposed CAC scheme can maintain the CDP below a predefined threshold, and the\r\nCBP is also lower than the cluster prediction and traditional guard channel policies....
We propose an FDI system for the wind turbine benchmark designed by the application of a generic automated method. No\r\nspecific adaptation of the method for the wind turbine benchmark is needed, and the number of required human decisions,\r\nassumptions, as well as parameter choices is minimized. The method contains in essence three steps: generation of candidate\r\nresidual generators, residual generator selection, and diagnostic test construction. The proposed FDI system performs well in spite\r\nof no specific adaptation or tuning to the benchmark. All faults in the predefined test sequence can be detected and all faults, except\r\na double fault, can also be isolated shortly thereafter. In addition, there are no false or missed detections....
This paper studies the design of efficient model predictive controllers for fast-sampling linear time-invariant systems subject to\r\ninput constraints to track a set of periodic references. The problem is decomposed into a steady-state subproblem that determines\r\nthe optimal asymptotic operating point and a transient subproblem that drives the given plant to this operating point. While the\r\ntransient subproblem is a small-sized quadratic program, the steady-state subproblem can easily involve hundreds of variables\r\nand constraints. The decomposition allows these two subproblems of very different computational complexities to be solved in\r\nparallel with different sampling rates.Moreover, a receding horizon approach is adopted for the steady-state subproblem to spread\r\nthe optimization over time in an efficient manner, making its solution possible for fast-sampling systems. Besides the conventional\r\nformulation based on the control inputs as variables, a parameterization using a dynamic policy on the inputs is introduced, which\r\nfurther reduces the online computational requirements. Both proposed algorithms possess nice convergence properties, which are\r\nalso verified with computer simulations....
This paper is concerned with non-fragile sliding mode control of uncertain chaotic systems with external disturbance. Firstly, a new\r\nsliding surface is proposed, and sufficient conditions are derived to guarantee that sliding mode dynamics is asymptotically stable\r\nwith a generalized H2 disturbance rejection level. Secondly, non-fragile sliding mode controller is established to make the state of\r\nsystem reach the sliding surface in a finite time. Finally, an example is given to illustrate the effectiveness of the proposed method....
Despite their interesting dynamic and controllability properties, sailing vehicles have not been much studied in the control\r\ncommunity. In this paper, we investigate motion planning of such vehicles. Starting from a simple dynamic model of sailing vessels\r\nin one dimension, this paper first considers their associated controllability issues, with the so-called no-sailing zone as a starting\r\npoint, and it links them with a motion planning strategy using two-point boundary value problems as the main mathematical tool.\r\nThis perspective is then expanded to do point-to-point maneuvers of sailing vehicles in the plane, that is, automatic path generation\r\ncombined with computation of control input profiles. Simulations are presented to illustrate the potential of the approach....
This paper presents a perfect tracking optimal control for discrete-time nonminimum phase of electrohydraulic actuator (EHA)\r\nsystem by adopting a combination of feedback and feedforward controller. A linear-quadratic regulator (LQR) is firstly designed\r\nas a feedback controller, and a feedforward controller is then proposed to eliminate the phase error emerged by the LQR controller\r\nduring the tracking control. The feedforward controller is developed by implementing the zero phase error tracking control\r\n(ZPETC) technique in which the main difficulty arises from the nonminimum phase system with no stable inverse. Subsequently,\r\nthe proposed controller is performed in simulation and experimental studies where the EHA system is represented in discrete-time\r\nmodel that has been obtained using system identification technique. It also shows that the controller offers better performance as\r\ncompared to conventional PID controller in reducing phase and gain error that typically occurred in positioning or tracking\r\nsystems....
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