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Conference on Wireless Advanced (WiAD)

作者： Pyari Mohan Pradhan Ganapati Panda Babita Majhi School of Electrical Sciences Indian Institute of Technology Bhubaneswar Bhubaneswar India Department of Automatic Control and Systems Engineering University of Sheffield Sheffield UK

Cognitive radio has emerged as a potential solution to the problem of spectrum scarcity. Cooperative spectrum sensing exploits the spatial diversity between cognitive radios for reliable detection of primary users' signals. The selection of weight and decision threshold for each cognitive radio can be formulated as a constrained multiobjective optimization problem where probabilities of false alarm and detection are the two conflicting objectives. This paper uses multiobjective cat swarm optimization in the field of cooperative spectrum sensing. The simulation results show that our proposed approach performs better in terms of efficient computation and quality of nondom-inating solutions.

关键词： Sensors Measurement Noise Cognitive radio Optimization Wireless sensor networks

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Robust stability of nonlinear model predictive control based on extended Kalman filter

Robust stability of nonlinear model predictive control based...

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作者： Huang, Rui Patwardhan, Sachin C. Biegler, Lorenz T. Collaboratory for Process and Dynamic Systems Research National Energy Technology Laboratory P.O. Box 880 Morgantown WV 26507-0880 United States Department of Chemical Engineering Carnegie Mellon University 5000 Forbes Avenue Pittsburgh PA 15213 United States United Technology Research Center 411 Silver Lane East Hartford CT 06108 United States Department of Chemical Engineering Indian Institute of Technology Bombay Mumbai 400076 Maharashtra India

This work deals with state estimation and process control for nonlinear systems, especially when nonlinear model predictive control (NMPC) is integrated with extended Kalman filter (EKF) as the state estimator. In particular, we focus on the robust stability of NMPC and EKF in the presence of plant-model mismatch. The convergence property of the estimation error from the EKF in the presence of non-vanishing perturbations is established based on our previous work [1]. In addition, a so-called one way interaction is shown that the EKF error is not influenced by control action from the NMPC. Hence, the EKF analysis is still valid in the output-feedback NMPC framework, even though there is no separation principle for general nonlinear systems. With this result, we study the robust stability of the output-feedback NMPC under the impact of the estimation error. It turns out the output-feedback NMPC with EKF is Input-to-State practical Stable (ISpS). Finally, two offset-free strategies of output-feedback NMPC are presented and illustrated through a simulation example. © 2011 Elsevier Ltd. All Rights Reserved.

关键词： Extended Kalman filters

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Developments in dependability modeling of Networked control systems

Developments in dependability modeling of Networked Control ...

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UKACC International Conference on control (control)

作者： Manoj Kumar A.K. Verma A. Srividya P.P. Marathe Control Instrumentation Division Bhabha Atomic Research Centre Mumbai India Stord Haugesund University College Haugesund Norway Department of Civil Engineering Indian Institute of Technology Bombay Mumbai India

Networked control systems (NCS) are in existence for quite some time. The network-induced delays and packet drops; and their effect on control system's performance has been a burning topic for last one decade. Dependability in context of NCS has not got much attention. While it is an important aspect of NCS intended to be used in critical application. The paper reviews the present state of developments in NCS and presents open problems pertaining to dependability of NCS. Solutions to these problems may increase the presence of NCS by many folds and in many fields.

关键词： Delay Analytical models Networked control systems Actuators Real-time systems Stability analysis

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Flux estimation from Vanadium and Cobalt Self Powered Neutron Detectors (SPNDs): Nonlinear exact inversion and Kalman filter approaches

Flux estimation from Vanadium and Cobalt Self Powered Neutro...

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American control Conference (ACC)

作者： Krishnan Srinivasarengan Laxman Mutyam Madhu N. Belur Mani Bhushan A. P. Tiwari M. G. Kelkar M. Pramanik Department of Electrical Engineering Indian Institute of Technology Bombay India Reactor Control Division Bhabha Atomic Research Center Mumbai India Nuclear Power Corporation of India Ltd. Mumbai India

Self Powered Neutron Detectors (SPNDs), which are widely used in a nuclear reactor for flux measurement, typically have different types of dynamics based on their emitter material: one delayed, second prompt and possibly nonlinear response characteristics. The measurement from the SPNDs hence need compensation to obtain the actual input flux. In this paper, we discuss the modeling of and input estimation design for Vanadium and Cobalt SPNDs. We obtain the structure and parameters of the Vanadium SPND model from its radioactive decay mechanism. We then obtain the other parameters of the model applying system identification tools on the available data corresponding to reactor trip. For Cobalt SPND, we design two model based input/state estimators; the nonlinearity being the key feature: the `Exact Model Inversion' and the Extended Kalman filter. In the exact model inversion, we demonstrate that input flux can be calculated by solving a third degree polynomial. In the extended Kalman filter estimator, we propose a novel approach to improve the step response of Kalman filter algorithms by `resetting' the state error covariance matrix. We use Matlab ® simulation and reactor data to compare the advantages of the two filters. We show that in both Vanadium and Cobalt SPND cases, Kalman filter based algorithms provide a reasonable balance between speed and noise suppression. While the exact inversion provides an almost prompt, but noisy response to step changes, the modified Kalman filter has a noise-free response with a few minutes of settling time. We also demonstrate the ability of the proposed covariance reset Kalman filter to track step/sudden changes in the input.

关键词： Kalman filters Mathematical model Cobalt Neutrons Inductors Estimation Noise

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Hysteresis and remanence in magnetoelectric effects in functionally graded magnetostrictive-piezoelectric layered composites

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Physical Review B 2012年第10期85卷 104404-104404页

作者： U. Laletin G. Sreenivasulu V. M. Petrov T. Garg A. R. Kulkarni N. Venkataramani G. Srinivasan Physics Department Oakland University Rochester Michigan 48309 USA Institute of Technical Acoustics National Academy of Sciences of Belarus 13 Ludnikov Avenue Vitebsk 210023 Belarus Institute of Electronic and Information Systems Novgorod State University Veliky Novgorod 173003 Russia Metallurgical Engineering and Materials Science Department Indian Institute of Technology Bombay Mumbai 400076 India

The observation and theory of a large remanent magnetoelectric (ME) coefficient and coercivity in the static field H dependence of the low-frequency ME effects are reported for bilayers of lead zirconate titanate (PZT) and a functionally graded ferromagnetic layer. The grading involves magnetization with the use of nickel zinc ferrite of composition Ni0.7Zn0.3Fe2O4 (NZFO) and pure Ni. In homogeneous bilayers of PZT-Ni or PZT-NZFO, the ME voltage coefficient (MEVC) vs H data do not show any hysteresis or remanence. Upon grading the ferromagnetic layer, significant changes including hysteresis and remanece are observed. In PZT-Ni-NZFO, MEVC vs H data show a positive remnant MEVC and a negative coercive field. When the grading is reversed, in samples of PZT-NZFO-Ni, the remnant MEVC is negative and the coercive field is positive. A theory is proposed for the low-frequency ME effects in the graded composites. According to the model, the grading in the magnetization leads to a built-in magnetic field in the ferromagnetic layer, and this field depends on the sequence of grading and the thickness of the NZFO and Ni layers. As a result, the total torque moment and flexural deformations in the composite and the bias field dependence of ME voltage coefficient becomes strongly hysteretic. Calculated MEVC vs H, remnant MEVC, and coercive field are in good agreement with the data.

关键词： SPINTRONICS MAGNETOSTRICTION PIEZOELECTRICITY HYSTERESIS LEAD zirconate titanate MAGNETIC fields MAGNETIZATION

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Single image based depth estimation for robotic applications

Single image based depth estimation for robotic applications

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2011 IEEE Recent Advances in Intelligent Computational systems, RAICS 2011

作者： Sabnis, Anupa Vachhani, Leena Interdisciplinary Programme in Systems and Control Indian Institute of Technology Bombay Mumbai 400076 India

ISBN: (纸本)9781424494774

Goal of the robot vision is to exploit power of visual sensing to observe and perceive the environment and react it. Visual feedback is used to manipulate the robot among objects by estimating their depths. This paper presents a depth estimation technique based on the defocus blur associated with a camera setting. A sharp image of an object is obtained from a defocused image of the same object by applying sharpening filter. The defocused and sharp images of the object are used to calculate the spread parameter which is related to the object depth. The method calculates the constant camera parameters. The main advantage of this method is use of a single image by the robot to estimate depth. The method is independent of illumination condition and can be applied to the images with different edge orientations. Experiments on real scene images have demonstrated the feasibility of the proposed method for depth estimation. The results indicate that the depth estimation average errors are within two percent of true values. The proposed method is compared with the existing methods. © 2011 IEEE.

关键词： Robot vision

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The extrapolated Taylor model

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Reliable Computing 2011年第3期15卷 251-278页

作者： Nataraj, P.S.V. Sondur, Shanta IDP in Systems and Control Engineering Indian Institute of Technology Bombay Mumbai India

The Taylor model [8] is one of the inclusion functions available to compute the range enclosures. It has the property of (m + 1)th convergence order, where, m is the order of the Taylor model used. It computes a high order polynomial approximation to a multivariate Taylor expansion, with a remainder term that rigorously bound the approximation error. The sharper bounds on the enclosures computed using the Taylor model can be obtained either by successively partitioning the domain x using suitable subdivision factors, or by increasing the convergence rate of the Taylor model using higher order Taylor models. However, higher order Taylor forms require higher degrees of the polynomial part, which in turn require more computational effort and more memory. This is the major drawback of increasing the order m of Taylor models for obtaining range enclosures with higher order convergence rates. In this paper, we attempt to overcome these drawbacks by using a lower order Taylor model, and then using extrapolation to accelerate the convergence process of the sequences generated with the lower order Taylor model. The effectiveness of all the proposed algorithms is tested on various multivariate examples and compared with the conventional methods. The test results show that the proposed extrapolation-based methods offer considerable speed improvements over the conventional methods.

关键词： Enclosures

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control of a nuclear steam generator using feedback-feedforward LQG controller

Control of a nuclear steam generator using feedback-feedforw...

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作者： Parikh, Nishant Patwardhan, Sachin Bandyopadhyay, Santanu Gudi, Ravindra School of Petroleum Technology Pandit Deendayal Petroleum University Raisan Gandhinagar Gujarat India Department of Chemical Engineering Indian Institute of Technology Bombay India Department of Energy Systems Engineering Indian Institute of Technology Bombay India

Steam Generator (SG) is a major component in a nuclear power plant. Poor control of a nuclear steam generator can lead to frequent reactor shutdowns or it can damage turbine blades. To avoid such costly reactor shutdowns, there is a need to systematically investigate the problem of controlling the water level in the steam generator. In this work, we have proposed a novel concept of feedback-feedforward Linear Quadratic Gaussian (LQG) control scheme to achieve efficient servo and regulatory control of SG. The benchmark nonlinear dynamic model proposed by Astrom [1] has been simulated using MATLAB to carry out simulation studies. The major disturbance in a steam generator is steam demand and the proposed controller is capable of initiating a feedforward action in response to steam demand changes. This approach employs a Kalman filter for state estimation and uses estimation error feedback to achieve offset free closed-loop behavior. The closed-loop responses can be shaped using additional filters introduced to mitigate sudden changes in the setpoint and unmeasured disturbances. Finally, simulation results shows the effectiveness and the improved performance of the proposed method. © 2011 Zhejiang University.

关键词： Steam generators

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Quasi sliding mode control with quantization in state measurement

Quasi sliding mode control with quantization in state measur...

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Annual Conference of Industrial Electronics Society

作者： S. Chakrabarty B. Bandyopadhyay Interdisciplinary Programme in Systems and Control Engineering Indian Institute of Technology Bombay India

Whenever we compute control using digital computer, the states measured need to be converted to digital word before processing in the computer. This conversion gives rise to quantization error in state measurement which in turn affects the applied control to the plant. This would cause the system dynamics to deviate from the behaviour predicted by any theoretical analysis which does not consider the effect of such quantization. Here an analysis has been presented taking into consideration the error due to quantization for Quasi Sliding Mode control with state feedback.

关键词： Quantization Uncertainty Measurement uncertainty Sliding mode control State feedback Mathematical model Equations

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An Interval Newton method based on the Bernstein form for bounding the zeros of polynomial systems

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Reliable Computing 2011年第2期15卷 109-119页

作者： Nataraj, P.S.V. Arounassalame, M. Systems and Control Engineering CRNTS Building Indian Institute of Technology Bombay Mumbai-400 076 India

Interval Newton methods are widely used to find reliable enclosures for the roots of the polynomial systems. But the computation process needs the evaluation of an enclosure for the derivative of the polynomial and evaluation of the polynomial at a particular point. Again, the subdivisions (if any are needed) will require repeated evaluation of the function values. We propose an alternative approach using Bernstein coefficients to find the value of the Newton operator. This Bernstein Newton operator doesn't require evaluation of the function at any particular point. Instead the function value is obtained directly from the vertex points. Again the computation of the derivative is very simple using the Bernstein coefficient approach. In addition to this the range enclosures obtained using Bernstein coefficients are much sharper than the range enclosures obtained using many other interval forms. We compare the performance of the proposed Bernstein Newton Contractor with that of Interval Newton contractor using numerical examples, proving the superiority of the proposed approach.

关键词： Enclosures

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