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Sample records for feedback linearization based

  1. Feedback Linearization Based Arc Length Control for Gas Metal Arc Welding

    DEFF Research Database (Denmark)

    Thomsen, Jesper Sandberg

    2005-01-01

    In this paper a feedback linearization based arc length controller for gas metal arc welding (GMAW) is described. A nonlinear model describing the dynamic arc length is transformed into a system where nonlinearities can be cancelled by a nonlinear state feedback control part, and thus, leaving only...

  2. Analysis of exact linearization and aproximate feedback linearization techniques

    OpenAIRE

    Schnitman, Leizer; Cardoso, Gildeberto de Souza

    2011-01-01

    p. 1-17 This paper presents a study of linear control systems based on exact feedback linearization and approximate feedback linearization. As exact feedback linearization is applied, a linear controller can perform the control objectives. The approximate feedback linearization is required when a nonlinear system presents a noninvolutive property. It uses a Taylor series expansion in order to compute a nonlinear transformation of coordinates to satisfy the involutivity conditions.

  3. Analysis of Exact Linearization and Aproximate Feedback Linearization Techniques

    OpenAIRE

    Cardoso, Gildeberto S.; Leizer Schnitman

    2011-01-01

    This paper presents a study of linear control systems based on exact feedback linearization and approximate feedback linearization. As exact feedback linearization is applied, a linear controller can perform the control objectives. The approximate feedback linearization is required when a nonlinear system presents a noninvolutive property. It uses a Taylor series expansion in order to compute a nonlinear transformation of coordinates to satisfy the involutivity conditions.

  4. Sliding Mode Control Approach for Electrically Controllable Clutch of AMT Based on the Feedback Linearization

    Institute of Scientific and Technical Information of China (English)

    程东升; 张建武; 叶晓峰; 黄维纲

    2003-01-01

    A sliding mode control approach based on the feedback linearization is proposed for the electrically controllable clutch of AMT vehicles. The nonlinear dynamic model for the hydraulic actuator associated with clutch is established. By means of the exact feedback linearization procedure of differential geometry, an equivalent, fully controllable and linear model is derived via a homomorphic transformation for the AMT clutch system.Furthermore, a sliding mode control is introduced to improve robustness. The tracking tests are performed using the sliding mode control on a Santana LX passenger car, and the experimental results prove that this nonlinear controller is of fine robustness and high degree of tracking accuracy.

  5. Neural-networks-based feedback linearization versus model predictive control of continuous alcoholic fermentation process

    Energy Technology Data Exchange (ETDEWEB)

    Mjalli, F.S.; Al-Asheh, S. [Chemical Engineering Department, Qatar University, Doha (Qatar)

    2005-10-01

    In this work advanced nonlinear neural networks based control system design algorithms are adopted to control a mechanistic model for an ethanol fermentation process. The process model equations for such systems are highly nonlinear. A neural network strategy has been implemented in this work for capturing the dynamics of the mechanistic model for the fermentation process. The neural network achieved has been validated against the mechanistic model. Two neural network based nonlinear control strategies have also been adopted using the model identified. The performance of the feedback linearization technique was compared to neural network model predictive control in terms of stability and set point tracking capabilities. Under servo conditions, the feedback linearization algorithm gave comparable tracking and stability. The feedback linearization controller achieved the control target faster than the model predictive one but with vigorous and sudden controller moves. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  6. Robust Feedback Linearization-based Control Design for a Wheeled Mobile Robot

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon; Andersen, Palle; Pedersen, Tom Søndergaard

    This paper considers the trajectory tracking problem for a four-wheel driven, four-wheel steered mobile robot moving in outdoor terrain. The robot is modeled as a non-holonomic dynamic system subject to pure rolling, no-slip constraints. A nonlinear trajectory tracking feedback control law based...... on dynamic feedback linearization is designed for this model. Since several parameters in the model, in particular the ground-wheel contact friction, are not well known a priori, a robustness analysis is carried out for bounded uncertainties. It is demonstrated that uncertainties can render the closed...

  7. Robust Feedback Linearization-based Control Design for a Wheeled Mobile Robot

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon; Andersen, Palle; Pedersen, Tom Søndergaard

    2002-01-01

    This paper considers the trajectory tracking problem for a four-wheel driven, four-wheel steered mobile robot moving in outdoor terrain. The robot is modeled as a non-holonomic dynamic system subject to pure rolling, no-slip constraints. A nonlinear trajectory tracking feedback control law based...... on dynamic feedback linearization is designed for this model. Since several parameters in the model, in particular the ground-wheel contact friction, are not well known a priori, a robustness analysis is carried out for bounded uncertainties. It is demonstrated that uncertainties can render the closed...

  8. TCSC controller design based on output feedback control with linear matrix inequality

    Energy Technology Data Exchange (ETDEWEB)

    Ishimaru, Masachika; Shirai, Goro [Hosei University, Tokyo (Japan). Dept. of Electrical Engineering; Niioka, Satoru; Yokoyama, Ryuichi [Tokyo Metropolitan University (Japan). Dept. of Electrical Engineering

    2000-07-01

    The authors aim at designing the fast responsible and robust stabilizing controller. Recently, many researches propose robust stabilizing compensators based on H{sub {infinity}} control theory. Especiady, the LMI (Linear Matrix Inequality) solving efficient convex problems is very effective. LMI is based on a linear function composed by matrices, and it is expansion of conventional H{sub {infinity}} control. In addition to the LMI approach, authors pay attention to the output-feedback control for stabilizing a system using observable output values. This paper presents a stabilizing control using measurable values by using the output-feedback method. In order to discuss the advantage of the proposed method, 3-machine 9-bus system is used. Moreover, this system is applied TCSC (Thyristor Controlled Series Capacitor) controllers, and H{sub {infinity}} control based on the LMI is proposed for the design method of TCSC controllers to attain the robust stability. (author)

  9. Feedback linearization of piecewise linear systems

    NARCIS (Netherlands)

    Camlibel, Kanat; Ustoglu, Ilker

    2005-01-01

    One of the classical problems of nonlinear systems and control theory is feedback linearization. Its obvious motivation is that one can utilize linear control theory if the nonlinear system at hand is linearizable by feedback. This problem is well-understood for the smooth nonlinear systems. In the

  10. Observer-based output feedback control of discrete-time linear systems with input and output delays

    Science.gov (United States)

    Zhou, Bin

    2014-11-01

    In this paper, we study observer-based output feedback control of discrete-time linear systems with both multiple input and output delays. By generalising our recently developed truncated predictor feedback approach for state feedback stabilisation of discrete-time time-delay systems to the design of observer-based output feedback, two types of observer-based output feedback controllers, one being memory and the other memoryless, are constructed. Both full-order and reduced-order observer-based controllers are established in both the memory and memoryless schemes. It is shown that the separation principle holds for the memory observer-based output feedback controllers, but does not hold for the memoryless ones. We further show that the proposed observer-based output feedback controllers solve both the l2 and l∞ semi-global stabilisation problems. A numerical example is given to illustrate the effectiveness of the proposed approaches.

  11. Differential-Drive Mobile Robot Control Design based-on Linear Feedback Control Law

    Science.gov (United States)

    Nurmaini, Siti; Dewi, Kemala; Tutuko, Bambang

    2017-04-01

    This paper deals with the problem of how to control differential driven mobile robot with simple control law. When mobile robot moves from one position to another to achieve a position destination, it always produce some errors. Therefore, a mobile robot requires a certain control law to drive the robot’s movement to the position destination with a smallest possible error. In this paper, in order to reduce position error, a linear feedback control is proposed with pole placement approach to regulate the polynoms desired. The presented work leads to an improved understanding of differential-drive mobile robot (DDMR)-based kinematics equation, which will assist to design of suitable controllers for DDMR movement. The result show by using the linier feedback control method with pole placement approach the position error is reduced and fast convergence is achieved.

  12. Feedback systems for linear colliders

    CERN Document Server

    Hendrickson, L; Himel, Thomas M; Minty, Michiko G; Phinney, N; Raimondi, Pantaleo; Raubenheimer, T O; Shoaee, H; Tenenbaum, P G

    1999-01-01

    Feedback systems are essential for stable operation of a linear collider, providing a cost-effective method for relaxing tight tolerances. In the Stanford Linear Collider (SLC), feedback controls beam parameters such as trajectory, energy, and intensity throughout the accelerator. A novel dithering optimization system which adjusts final focus parameters to maximize luminosity contributed to achieving record performance in the 1997-98 run. Performance limitations of the steering feedback have been investigated, and improvements have been made. For the Next Linear Collider (NLC), extensive feedback systems are planned as an intregal part of the design. Feedback requiremetns for JLC (the Japanese Linear Collider) are essentially identical to NLC; some of the TESLA requirements are similar but there are significant differences. For NLC, algorithms which incorporate improvements upon the SLC implementation are being prototyped. Specialized systems for the damping rings, rf and interaction point will operate at hi...

  13. Neural Network Based Feedback Linearization Control of an Unmanned Aerial Vehicle

    Institute of Scientific and Technical Information of China (English)

    Dan Necsulescu; Yi-Wu Jiang; Bumsoo Kim

    2007-01-01

    This paper presents a flight control design for an unmanned aerial vehicle (UAV) using a nonlinear autoregressive moving average (NARMA-L2) neural network based feedback linearization and output redefinition technique. The UAV investigated is nonminimum phase. The output redefinition technique is used in such a way that the resulting system to be inverted is a minimum phase system. The NARMA-L2 neural network is trained off-line for forward dynamics of the UAV model with redefined output and is then inverted to force the real output to approximately track a command input. Simulation results show that the proposed approaches have good performance.

  14. The Design of Ship Autopilot by Applying Observer - Based Feedback Linearization

    Directory of Open Access Journals (Sweden)

    Zwierzewicz Zenon

    2015-01-01

    Full Text Available The paper considers the problem of ship autopilot design based on Bech’s model of the vessel. Since the model is highly nonlinear and some of the state vector coordinates are unavailable, the control system synthesis is performed by means of an output feedback linearization method combined with a nonlinear observer. The asymptotic stability of the overall system has been proven, including the asymptotic stability of the system internal dynamics. The performed simulations of the ship course-changing process have confirmed a high performance of the proposed controller. It has been emphasized that for its practical usability the system robustification is necessary.

  15. Robust Control Based on Feedback Linearization for Roll Stabilizing of Autonomous Underwater Vehicle Under Wave Disturbances

    Institute of Scientific and Technical Information of China (English)

    PAN Li-xin; JIN Hong-zhang; WANG Lin-lin

    2011-01-01

    In the case of Autonomous Underwater Vehicle (AUV) navigating with low speed near water surface, a new method for design of roll motion controller is proposed in order to restrain wave disturbance effectively and improve roll stabilizing performance. Robust control is applied, which is based on uncertain nonlinear horizontal motion model of AUV and the principle of zero speed fin stabilizer. Feedback linearization approach is used to transform the complex nonlinear system into a comparatively simple linear system. For parameter uncertainty of motion model, the controller is designed with mixed-sensitivity method based on H-infinity robust control theory. Simulation results show better robustness improved by this control method for roll stabilizing of AUV navigating near water surface.

  16. Feedback linearization based control of a variable air volume air conditioning system for cooling applications.

    Science.gov (United States)

    Thosar, Archana; Patra, Amit; Bhattacharyya, Souvik

    2008-07-01

    Design of a nonlinear control system for a Variable Air Volume Air Conditioning (VAVAC) plant through feedback linearization is presented in this article. VAVAC systems attempt to reduce building energy consumption while maintaining the primary role of air conditioning. The temperature of the space is maintained at a constant level by establishing a balance between the cooling load generated in the space and the air supply delivered to meet the load. The dynamic model of a VAVAC plant is derived and formulated as a MIMO bilinear system. Feedback linearization is applied for decoupling and linearization of the nonlinear model. Simulation results for a laboratory scale plant are presented to demonstrate the potential of keeping comfort and maintaining energy optimal performance by this methodology. Results obtained with a conventional PI controller and a feedback linearizing controller are compared and the superiority of the proposed approach is clearly established.

  17. A Study on Missile Reentry Control Based on the Method of Feedback Linearization

    Institute of Scientific and Technical Information of China (English)

    LIU Yu-xi; ZHOU Jun; ZHOU Feng-qi

    2007-01-01

    In the process of missile large attack angle reentry, there exist nonlinear, strong coupling uncertainty and multiinput-multi-output (MIMO) in the movement equations, so the traditional small disturbance faces difficulties. For such situations, the method of feedback linearization is adopted to control the complex system, and the control method based on the fuzzy adaptive nonlinear dynamic inversion decoupling control of missile is proposed in the paper. According to the principle of time-scale separation, the system is separated into fast loop and slow loop, the method of dynamic inversion is applied to them, and the method of adaptive fuzzy approach is adopted to compensate for the uncertainty of the fast loop.The simulation results denote the control method in the paper has a better tracing characteristic and robustness.

  18. Linear feedback controls the essentials

    CERN Document Server

    Haidekker, Mark A

    2013-01-01

    The design of control systems is at the very core of engineering. Feedback controls are ubiquitous, ranging from simple room thermostats to airplane engine control. Helping to make sense of this wide-ranging field, this book provides a new approach by keeping a tight focus on the essentials with a limited, yet consistent set of examples. Analysis and design methods are explained in terms of theory and practice. The book covers classical, linear feedback controls, and linear approximations are used when needed. In parallel, the book covers time-discrete (digital) control systems and juxtapos

  19. Feedback Linearization and Sliding Mode Control for VIENNA Rectifier Based on Differential Geometry Theory

    Directory of Open Access Journals (Sweden)

    Xiang Lu

    2015-01-01

    Full Text Available Aiming at the nonlinear characteristics of VIENNA rectifier and using differential geometry theory, a dual closed-loop control strategy is proposed, that is, outer voltage loop using sliding mode control strategy and inner current loop using feedback linearization control strategy. On the basis of establishing the nonlinear mathematical model of VIENNA rectifier in d-q synchronous rotating coordinate system, an affine nonlinear model of VIENNA rectifier is established. The theory of feedback linearization is utilized to linearize the inner current loop so as to realize the d-q axis variable decoupling. The control law of outer voltage loop is deduced by utilizing sliding mode control and index reaching law. In order to verify the feasibility of the proposed control strategy, simulation model is built in simulation platform of Matlab/Simulink. Simulation results verify the validity of the proposed control strategy, and the controller has a strong robustness in the case of parameter variations or load disturbances.

  20. Piecewise output feedback control for affine systems with disturbances based on linear temporal logic specifications

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In the paper,we investigate the problem of finding a piecewise output feedback control law for an uncertain affine system such that the resulting closed-loop output satisfies a desired linear temporal logic (LTL) specification.A two-level hierarchical approach is proposed to solve the problem in a triangularized output space.In the lower level,we explore whether there exists a robust output feedback control law to make the output starting in a simplex either remains in it or leaves via a specific facet.In t...

  1. Dynamic feedback linearization control of spacecraft with flexible appendages based on extended state observer

    Science.gov (United States)

    Chen, Jinli; Li, Donghai; Sun, Xianfang

    2006-11-01

    A dynamic feedback linearization control approach is designed in this paper for the pitch angle trajectory control and vibration suppression of a flexible spacecraft. Using the extended state observer, the pitch rate and entire unknown dynamics can be estimated, so only pitch angle is needed to measure in the feedback linearization control. The expression of the control law is simple, and few observer parameters need to be tuned. These all reduce the engineering difficulty greatly. The design of this control law does not depend on elastic modes included in the spacecraft model. Simulation results are presented to show that, the control law designed can ensure that pitch angle maneuver to its target precisely and smoothly, and elastic vibration is suppressed effectively.

  2. Secure binary arithmetic coding based on digitalized modified logistic map and linear feedback shift register

    Science.gov (United States)

    Zhang, Yushu; Xiao, Di; Wen, Wenying; Nan, Hai; Su, Moting

    2015-10-01

    In this paper, we propose a novel secure arithmetic coding based on digitalized modified logistic map (DMLM) and linear feedback shift register (LFSR). An input binary sequence is first mapped into a table, which is then scrambled by two cyclic shift steps driven by the keys resulting from DMLM-LFSR. Next, each column is encoded using traditional arithmetic coding (TAC) and randomized arithmetic coding (RAC). During the RAC process, the exchange of two intervals is controlled by the keystream generated from the DMLM. At the same time, a few bits of the present column sequence are extracted to interfere the generation of new keystream used for the next column. The final ciphertext sequence is obtained by XORing the compressed sequence and the keystream generated by the LFSR. Results show the compression ratio of our scheme is slightly higher than that of TAC, but the security is improved due to the architecture of shift-perturbance. DMLM and LFSR theories also ensure high sensitivity and strong randomness. The appended complexity is only O (N) , where N is the number of the input symbols.

  3. Logistic systems with linear feedback

    Science.gov (United States)

    Son, Leonid; Shulgin, Dmitry; Ogluzdina, Olga

    2016-08-01

    A wide variety of systems may be described by specific dependence, which is known as logistic curve, or S-curve, between the internal characteristic and the external parameter. Linear feedback between these two values may be suggested for a wide set of systems also. In present paper, we suggest a bifurcation behavior for systems with both features, and discuss it for two cases, which are the Ising magnet in external field, and the development of manufacturing enterprise.

  4. Feedback linearization application for LLRF control system

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, S.; Regan, A.; Wang, Y.M.; Rohlev, T.

    1999-06-01

    The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos National Laboratory will serve as the prototype for the low energy section of Acceleration Production of Tritium (APT) accelerator. This paper addresses the problem of the LLRF control system for LEDA. The authors propose a control law which is based on exact feedback linearization coupled with gain scheduling which reduces the effect of the deterministic klystron cathode voltage ripple that is due to harmonics of the high voltage power supply and achieves tracking of desired set points. Also, they propose an estimator of the ripple and its time derivative and the estimates based feedback linearization controller.

  5. Feedback linearization application for LLRF control system

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, S.; Regan, A.; Wang, Y.M.; Rohlev, T.

    1998-12-31

    The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos National Laboratory will serve as the prototype for the low energy section of Acceleration Production of Tritium (APT) accelerator. This paper addresses the problem of the LLRF control system for LEDA. The authors propose a control law which is based on exact feedback linearization coupled with gain scheduling which reduces the effect of the deterministic klystron cathode voltage ripple that is due to harmonics of the high voltage power supply and achieves tracking of desired set points. Also, they propose an estimator of the ripple and its time derivative and the estimates based feedback linearization controller.

  6. Design of Attitude Control System for UAV Based on Feedback Linearization and Adaptive Control

    Directory of Open Access Journals (Sweden)

    Wenya Zhou

    2014-01-01

    Full Text Available Attitude dynamic model of unmanned aerial vehicles (UAVs is multi-input multioutput (MIMO, strong coupling, and nonlinear. Model uncertainties and external gust disturbances should be considered during designing the attitude control system for UAVs. In this paper, feedback linearization and model reference adaptive control (MRAC are integrated to design the attitude control system for a fixed wing UAV. First of all, the complicated attitude dynamic model is decoupled into three single-input single-output (SISO channels by input-output feedback linearization. Secondly, the reference models are determined, respectively, according to the performance indexes of each channel. Subsequently, the adaptive control law is obtained using MRAC theory. In order to demonstrate the performance of attitude control system, the adaptive control law and the proportional-integral-derivative (PID control law are, respectively, used in the coupling nonlinear simulation model. Simulation results indicate that the system performance indexes including maximum overshoot, settling time (2% error range, and rise time obtained by MRAC are better than those by PID. Moreover, MRAC system has stronger robustness with respect to the model uncertainties and gust disturbance.

  7. Global-mode based linear feedback control of a supersonic jet for noise reduction

    Science.gov (United States)

    Natarajan, Mahesh; Freund, Jonathan; Bodony, Daniel

    2016-11-01

    The loudest source of high-speed jet noise appears to be describable by unsteady wavepackets that resemble instabilities. We seek to reduce their acoustic impact with a control strategy that uses global modes to model their dynamics and structural sensitivity of the linearized compressible Navier-Stokes operator to identify an effective linear feedback control. For a case with co-located actuators and sensors adjacent the nozzle, we demonstrate the method on an axisymmetric Mach 1.5 jet. Direct numerical simulations using this control show significant noise reduction. Eigenanalysis of the controlled mean flows reveal fundamental changes in the spectrum at frequencies lower than that used by the control, with the quieter flows having unstable eigenvalues that correspond to eigenfunctions without significant support in the acoustic field. A specific trend is observed in the mean flow quantities as the flow becomes quieter, with changes in the mean flow becoming significant only further downstream of the nozzle exit. The quieter flows also have a stable shock-cell structure that extends further downstream. A phase plot of the POD coefficients for the flows show that the quieter flows are more regular in time. Funded by the Office of Naval Research.

  8. Flatness-based linear output feedback control for disturbance rejection and tracking tasks on a Chua's circuit

    Science.gov (United States)

    Sira-Ramírez, H.; Luviano-Juárez, A.; Cortés-Romero, J.

    2012-05-01

    A linear output feedback controller is developed for trajectory tracking problems defined on a modified version of Chua's circuit. The circuit modification considers the introduction of a flat input, i.e. a suitable external control input channel guided by (a) the induction of the flatness property on a measurable output signal of the circuit and (b) the physical viability of the control input. A linear active disturbance rejection control based on a high-gain linear disturbance observer, is implemented on a laboratory prototype. We show that the state-dependent disturbance can be approximately, but arbitrarily closely, estimated through a linear high-gain observer, called a generalised proportional integral (GPI) observer, which contains a linear combination of a sufficient number of extra iterated integrals of the output estimation error. Experimental results are presented in the output reference trajectory tracking of a signal generated by an unrelated chaotic system of the Lorenz type. Laboratory experiments illustrate the proposed linear methodology for effectively controlling chaos.

  9. Formation Control of Multirobot Based on I/O Feedback Linearization and Potential Function

    Directory of Open Access Journals (Sweden)

    Jie Dong

    2014-01-01

    Full Text Available Standard techniques of I/O linearization are widely applied to leader-follower approach for multirobot formation control. However general leader-follower approach cannot adapt to the environment with obstacles. Concerning that issue, a formation control method of multirobot system based on potential function is proposed in this paper, and a new control law is designed by choosing a proper potential function and employing Lyapunov stability theory, which stabilizes the formation of the multirobot system. We combine the method with a leader-follower approach to solve the problem that the latter cannot avoid obstacles. Simulation results are given to validate the method.

  10. Feedback Quantization for Linear Precoded Spatial Multiplexing

    NARCIS (Netherlands)

    Simon, C.; Leus, G.

    2008-01-01

    This paper gives an overview and a comparison of recent feedback quantization schemes for linear precoded spatial multiplexing systems. In addition, feedback compression methods are presented that exploit the time correlation of the channel. These methods can be roughly divided into two classes. The

  11. Robust design of feedback feed-forward iterative learning control based on 2D system theory for linear uncertain systems

    Science.gov (United States)

    Li, Zhifu; Hu, Yueming; Li, Di

    2016-08-01

    For a class of linear discrete-time uncertain systems, a feedback feed-forward iterative learning control (ILC) scheme is proposed, which is comprised of an iterative learning controller and two current iteration feedback controllers. The iterative learning controller is used to improve the performance along the iteration direction and the feedback controllers are used to improve the performance along the time direction. First of all, the uncertain feedback feed-forward ILC system is presented by an uncertain two-dimensional Roesser model system. Then, two robust control schemes are proposed. One can ensure that the feedback feed-forward ILC system is bounded-input bounded-output stable along time direction, and the other can ensure that the feedback feed-forward ILC system is asymptotically stable along time direction. Both schemes can guarantee the system is robust monotonically convergent along the iteration direction. Third, the robust convergent sufficient conditions are given, which contains a linear matrix inequality (LMI). Moreover, the LMI can be used to determine the gain matrix of the feedback feed-forward iterative learning controller. Finally, the simulation results are presented to demonstrate the effectiveness of the proposed schemes.

  12. Vaccination strategies for SEIR models using feedback linearization. Preliminary results

    CERN Document Server

    De la Sen, M; Alonso-Quesada, S

    2011-01-01

    A linearization-based feedback-control strategy for a SEIR epidemic model is discussed. The vaccination objective is the asymptotically tracking of the removed-by-immunity population to the total population while achieving simultaneously the remaining population (i.e. susceptible plus infected plus infectious) to asymptotically tend to zero. The disease controlpolicy is designed based on a feedback linearization technique which provides a general method to generate families of vaccination policies with sound technical background.

  13. Negative Feedback, Linearity and Parameter Invariance in Linear Electronics

    CERN Document Server

    Costa, Luciano da F; Comin, Cesar H

    2016-01-01

    Negative feedback is a powerful approach capable of improving several aspects of a system. In linear electronics, it has been critical for allowing invariance to device properties. Negative feedback is also known to enhance linearity in amplification, which is one of the most important foundations of linear electronics. At the same time, thousands of transistors types have been made available, suggesting that these devices, in addition to their known variability of parameters, have distinguishing properties. The current work reports a systematic approach to quantifying the potential of negative feedback, with respect to bipolar transistors, as a means to providing device invariance and linearity. Several methods, including concepts from multivariate statistics and complex systems, are applied at the theoretical as well as experimental levels, and a number of interesting results are obtained and discussed. For instance, it has been verified that the transistors types indeed have well-defined characteristics wh...

  14. Direct torque and flux regulation of synchronous reluctance motor drives based on input-output feedback linearization

    Energy Technology Data Exchange (ETDEWEB)

    Abootorabi Zarchi, H., E-mail: abootorabi9@yahoo.co [Faculty of Electrical and Computer Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Arab Markadeh, Gh.R., E-mail: arab-gh@eng.sku.ac.i [Department of Engineering, Shahrekord University, Shahrekord (Iran, Islamic Republic of); Soltani, J., E-mail: j1234sm@cc.iut.ac.i [Faculty of Electrical and Computer Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of)

    2010-01-15

    In this paper, a nonlinear speed tracking controller is introduced for three-phase synchronous reluctance motor (SynRM) on the basis of input-output feedback linearization (IOFL), considering the different control strategies (maximum torque per Ampere, high efficiency and minimum KVA rating for the inverter) related to this motor. The proposed control approach is capable of decoupling control of stator flux and motor generated torque. The validity and effectiveness of the method is verified by simulation and experimental results.

  15. Output Feedback Based Admissible Control of Switched Linear Singular Systems%切换线性奇异系统输出反馈容许控制

    Institute of Scientific and Technical Information of China (English)

    孟斌; 张纪峰

    2006-01-01

    The admissibility analysis and robust admissible control problem of the uncertain discretetime switched linear singular (SLS) systems for arbitrary switching laws are investigated. Based on linear matrix inequalities, some sufficient conditions are given for: A) the existence of generalized common Lyapunov solution and the admissibility of the SLS systems for arbitrary switching laws,B) the existence of static output feedback control laws ensuring the admissibility of the closed-loop SLS systems for arbitrary switching laws and norm-bounded uncertainties.

  16. Linear Riccati Dynamics, Constant Feedback, and Controllability in Linear Quadratic Control Problems

    OpenAIRE

    Ronald J. Balvers; Douglas W. Mitchell

    2005-01-01

    Conditions are derived for linear-quadratic control (LQC) problems to exhibit linear evolution of the Riccati matrix and constancy of the control feedback matrix. One of these conditions involves a matrix upon whose rank a necessary condition and a sufficient condition for controllability are based. Linearity of Riccati evolution allows for rapid iterative calculation, and constancy of the control feedback matrix allows for time-invariant comparative static analysis of policy reactions.

  17. Design and Simulation of PMSM Feedback Linearization Control System

    Directory of Open Access Journals (Sweden)

    SONG Xiao-jing

    2013-01-01

    Full Text Available With the theory of AC adjustable speed as well as a new control theory research is unceasingly thorough, the permanent magnet synchronous motor control system requires high precision of control and high reliability of the occasion, access to a wide range of applications, in the modern AC motor has play a decisive role position. Based on the deep research on the feedback linearization technique based on, by choosing appropriate state transformation and control transform, PMSM model input output linearization, and the design of the feedback linearization controller, realized PMSM decoupling control based on Matlab, and PMSM feedback linearization control system simulation. The simulation results show that, the system in a certain range of speed than the traditional PI controller has better control performance, but to the parameter variation has strong sensitivity. It also determines the direction for future research. 

  18. An efficient feedback active noise control algorithm based on reduced-order linear predictive modeling of FMRI acoustic noise.

    Science.gov (United States)

    Kannan, Govind; Milani, Ali A; Panahi, Issa M S; Briggs, Richard W

    2011-12-01

    Functional magnetic resonance imaging (fMRI) acoustic noise exhibits an almost periodic nature (quasi-periodicity) due to the repetitive nature of currents in the gradient coils. Small changes occur in the waveform in consecutive periods due to the background noise and slow drifts in the electroacoustic transfer functions that map the gradient coil waveforms to the measured acoustic waveforms. The period depends on the number of slices per second, when echo planar imaging (EPI) sequencing is used. Linear predictability of fMRI acoustic noise has a direct effect on the performance of active noise control (ANC) systems targeted to cancel the acoustic noise. It is shown that by incorporating some samples from the previous period, very high linear prediction accuracy can be reached with a very low order predictor. This has direct implications on feedback ANC systems since their performance is governed by the predictability of the acoustic noise to be cancelled. The low complexity linear prediction of fMRI acoustic noise developed in this paper is used to derive an effective and low-cost feedback ANC system.

  19. Output feedback controller design for uncertain piecewise linear systems

    Institute of Scientific and Technical Information of China (English)

    Jianxiong ZHANG; Wansheng TANG

    2007-01-01

    This paper proposes output feedback controller design methods for uncertain piecewise linear systems based on piecewise quadratic Lyapunov function. The α-stability of closed-loop systems is also considered. It is shown that the output feedback controller design procedure of uncertain piecewise linear systems with α-stability constraint can be cast as solving a set of bilinear matrix inequalities (BMIs). The BMIs problem in this paper can be solved iteratively as a set of two convex optimization problems involving linear matrix inequalities (LMIs) which can be solved numerically efficiently. A numerical example shows the effectiveness of the proposed methods.

  20. Tracking control of robot manipulators via output feedback linearization

    Institute of Scientific and Technical Information of China (English)

    FEI Yue-nong; Wu Qing-hua

    2006-01-01

    This paper presents a robot manipulator tracking controller based on output feedback linearization.A sliding mode perturbation observer (SPO) is designed to estimate unmeasurable states and system perturbations that involve system nonlinearities,disturbances and unmodelled dynamics.The use of SPO allows to input/output linearize and decouple the strongly coupled nonlinear robot manipulator system merely by the feedback of joint angles.The controller design does not need an accurate model of the robot manipulator.Simulation studies are undertaken based on a two-link robot manipulator to evaluate the proposed approach.The simulation results show that the proposed controller has more superior tracking control performance,with payload changing in a wide range,in comparison with a sliding mode controller (SMC) designed based on state feedback linearization with full states available.

  1. Causal influence in linear Langevin networks without feedback

    Science.gov (United States)

    Auconi, Andrea; Giansanti, Andrea; Klipp, Edda

    2017-04-01

    The intuition of causation is so fundamental that almost every research study in life sciences refers to this concept. However, a widely accepted formal definition of causal influence between observables is still missing. In the framework of linear Langevin networks without feedback (linear response models) we propose a measure of causal influence based on a new decomposition of information flows over time. We discuss its main properties and we compare it with other information measures like the transfer entropy. We are currently unable to extend the definition of causal influence to systems with a general feedback structure and nonlinearities.

  2. Rotational Stabilization of Cylinder Wakes Using Linear Feedback Control

    Science.gov (United States)

    Borggaard, Jeff; Gugercin, Serkan; Zietsman, Lizette

    2015-11-01

    We demonstrate the feasibility of linear feedback control to stabilize vortex shedding behind twin cylinders using the cylinder rotations. Our approach is to linearize the flow about a desired steady-state flow, use interpolation-based model reduction on the resulting linear model to generate a low-dimensional model of the input-output system with input-independent error bounds, then use this reduced model to design the feedback control law. We then consider the practical issue of limited state measurements by building a nonlinear compensator that is computed from the same linear reduced-order model an constructed through an extended Kalman filter with a proper orthogonal decomposition (POD) model. Closed-loop simulations of the Navier-Stokes equations coupled with controls generated through flow measurements demonstrate the effectiveness of this control strategy. Supported in part by the National Science Foundation.

  3. Linearizing Intra-Train Beam-Beam Deflection Feedback

    Energy Technology Data Exchange (ETDEWEB)

    Smith, S.R.; /SLAC

    2006-02-22

    Beam-beam deflection feedback acting within the crossing time of a single bunch train may be needed to keep linear collider beams colliding at high luminosity. In a short-pulse machine such as the Next Linear Collider (NLC) this feedback must converge quickly to be useful. The non-linear nature of beam-beam deflection vs. beam-beam offset in these machines precludes obtaining both rapid convergence and a stable steady-state lock to beam offsets with a linear feedback algorithm. We show that a simply realizable programmable non-linear amplifier in the feedback loop can linearize the feedback loop, approximately compensating the beam-beam deflection non-linearity. Performance of a prototype non-linear amplifier is shown. Improvement of convergence and stability of the beam-beam feedback loop is simulated.

  4. Coherent versus Measurement Feedback: Linear Systems Theory for Quantum Information

    Science.gov (United States)

    Yamamoto, Naoki

    2014-10-01

    To control a quantum system via feedback, we generally have two options in choosing a control scheme. One is the coherent feedback, which feeds the output field of the system, through a fully quantum device, back to manipulate the system without involving any measurement process. The other one is measurement-based feedback, which measures the output field and performs a real-time manipulation on the system based on the measurement results. Both schemes have advantages and disadvantages, depending on the system and the control goal; hence, their comparison in several situations is important. This paper considers a general open linear quantum system with the following specific control goals: backaction evasion, generation of a quantum nondemolished variable, and generation of a decoherence-free subsystem, all of which have important roles in quantum information science. Some no-go theorems are proven, clarifying that those goals cannot be achieved by any measurement-based feedback control. On the other hand, it is shown that, for each control goal there exists a coherent feedback controller accomplishing the task. The key idea to obtain all the results is system theoretic characterizations of the above three notions in terms of controllability and observability properties or transfer functions of linear systems, which are consistent with their standard definitions.

  5. Coherent versus Measurement Feedback: Linear Systems Theory for Quantum Information

    Directory of Open Access Journals (Sweden)

    Naoki Yamamoto

    2014-11-01

    Full Text Available To control a quantum system via feedback, we generally have two options in choosing a control scheme. One is the coherent feedback, which feeds the output field of the system, through a fully quantum device, back to manipulate the system without involving any measurement process. The other one is measurement-based feedback, which measures the output field and performs a real-time manipulation on the system based on the measurement results. Both schemes have advantages and disadvantages, depending on the system and the control goal; hence, their comparison in several situations is important. This paper considers a general open linear quantum system with the following specific control goals: backaction evasion, generation of a quantum nondemolished variable, and generation of a decoherence-free subsystem, all of which have important roles in quantum information science. Some no-go theorems are proven, clarifying that those goals cannot be achieved by any measurement-based feedback control. On the other hand, it is shown that, for each control goal there exists a coherent feedback controller accomplishing the task. The key idea to obtain all the results is system theoretic characterizations of the above three notions in terms of controllability and observability properties or transfer functions of linear systems, which are consistent with their standard definitions.

  6. LQR-Based least-squares output feedback control of rotor vibrations using the complex mode and balanced realization methods. [Linear-Quadratic-Regulator

    Energy Technology Data Exchange (ETDEWEB)

    Fan, G.W. (3-I Scientific Development Inc., Tempe, AZ (United States)); Nelson, H.D. (Texas Christian Univ., Fort Worth (United States)); Crouch, P.E.; Mignolet, M.P. (Arizona State Univ., Tempe (United States))

    1993-04-01

    The complex mode and balanced realization methods are used separately to obtain reduced-order models for general linear asymmetric rotor systems. The methods are outlined and then applied to a typical rotor system represented by a 52 degree-or-freedom finite element model. The accuracy of the two methods is compared for this model and the complex model method is found to be more accurate than the balanced realization method for the desired frequency bandwidth and for models of the same reduced order. However, with some limitations, it is also shown that the balanced realization method can be applied to the reduced-order complex mode model to obtain further order reduction without loss of model accuracy. A Linear-Quadratic-Regulator-based least-squares output feedback control procedure is developed for the vibration control of rotor systems. This output feedback procedure eliminates the requirement of an observer for the use of an LQ regulator, and provides the advantage that the rotor vibration can be effectively controlled by monitoring only one single location along the rotor shaft while maintaining an acceptable performance. The procedures presented are quite general and may be applied to a large class of vibration problems including rotordynamics.

  7. Periodic feedback stabilization for linear periodic evolution equations

    CERN Document Server

    Wang, Gengsheng

    2016-01-01

    This book introduces a number of recent advances regarding periodic feedback stabilization for linear and time periodic evolution equations. First, it presents selected connections between linear quadratic optimal control theory and feedback stabilization theory for linear periodic evolution equations. Secondly, it identifies several criteria for the periodic feedback stabilization from the perspective of geometry, algebra and analyses respectively. Next, it describes several ways to design periodic feedback laws. Lastly, the book introduces readers to key methods for designing the control machines. Given its coverage and scope, it offers a helpful guide for graduate students and researchers in the areas of control theory and applied mathematics.

  8. State feedback control of switched linear systems: An LMI approach

    Science.gov (United States)

    Montagner, V. F.; Leite, V. J. S.; Oliveira, R. C. L. F.; Peres, P. L. D.

    2006-10-01

    This paper addresses the problem of state feedback control of continuous-time switched linear systems with arbitrary switching rules. A quadratic Lyapunov function with a common matrix is used to derive a stabilizing switching control strategy that guarantees: (i) the assignment of all the eigenvalues of each linear subsystem inside a chosen circle in the left-hand half of the complex plane; (ii) a minimum disturbance attenuation level for the closed-loop switched system. The proposed design conditions are given in terms of linear matrix inequalities that encompass previous results based on quadratic stability conditions with fixed control gains. Although the quadratic stability based on a fixed Lyapunov matrix has been widely used in robust control design, the use of this condition to provide a convex design method for switching feedback gains has not been fully investigated. Numerical examples show that the switching control strategy can cope with more stringent design specifications than the fixed gain strategy, being useful to improve the performance of this class of systems.

  9. High Accuracy Attitude Control of a Spacecraft Using Feedback Linearization

    Science.gov (United States)

    1992-05-01

    and Spacecraft Body from Gyro Measurements ......... .................................. 119 D.2 An Approximation to Exact Linearization using IPSRU...31 2-4 Attitude Determination and Control System Architecture ................. 33 3-1 Exact Linearization Using Nonlinear Feedback...though basic techniques were adapted from recent references on the use of exact linearization (such as [8] and [27]), the specific control approach

  10. Semi-global output regulation for linear systems with input saturation by composite nonlinear feedback control

    Science.gov (United States)

    Wang, Chongwen; Yu, Xiao; Lan, Weiyao

    2014-10-01

    To improve transient performance of output response, this paper applies composite nonlinear feedback (CNF) control technique to investigate semi-global output regulation problems for linear systems with input saturation. Based on a linear state feedback control law for a semi-global output regulation problem, a state feedback CNF control law is constructed by adding a nonlinear feedback part. The extra nonlinear feedback part can be applied to improve the transient performance of the closed-loop system. Moreover, an observer is designed to construct an output feedback CNF control law that also solves the semi-global output regulation problem. The sufficient solvability condition of the semi-global output regulation problem by CNF control is the same as that by linear control, but the CNF control technique can improve the transient performance. The effectiveness of the proposed method is illustrated by a disturbance rejection problem of a translational oscillator with rotational actuator system.

  11. Linear Feedback Synchronization Used in the Three-Dimensional Duffing System

    Directory of Open Access Journals (Sweden)

    Jian-qun Han

    2015-01-01

    Full Text Available It has been realized that synchronization using linear feedback control method is efficient compared to nonlinear feedback control method due to the less computational complexity and the synchronization error. For the problem of feedback synchronization of Duffing chaotic system, in the paper, we firstly established three-dimensional Duffing system by method of variable decomposition and, then, studied the synchronization of Duffing chaotic system and designed the control law based on linear feedback control and Lyapunov stability theory. It is proved theoretically that the two identical integer order chaotic systems are synchronized analytically and numerically.

  12. Robust control of robots via linear estimated state feedback

    NARCIS (Netherlands)

    Berghuis, Harry; Nijmeijer, Henk

    1994-01-01

    In this note we propose a robust tracking controller for robots that requires only position measurements. The controller consists of two parts: a linear observer part that generates an estimated error state from the error on the joint position and a linear feedback part that utilizes this estimated

  13. Tracking control of chaotic dynamical systems with feedback linearization

    Institute of Scientific and Technical Information of China (English)

    QI Dong-lian; MA Guo-jin

    2005-01-01

    A new method was proposed for tracking the desired output of chaotic dynamical system using the feedback linearization and nonlinear extended statement observer method. The feedback linearization was used to convert the nonlinear chaotic system into linear system. The extended Luenberger-like statements observer was designed to reconstructing and observing the unmeasured statements when the tracking controller was designed. By this way, the chaotic system could be forced to track variable desired output, which could be a time variant function or an equilibrium points.Taken the Lorenz chaotic system as example, the simulation results show the validity of the conclusion and effectiveness of the algorithm.

  14. Feedbacks, climate sensitivity, and the limits of linear models

    Science.gov (United States)

    Rugenstein, M.; Knutti, R.

    2015-12-01

    The term "feedback" is used ubiquitously in climate research, but implies varied meanings in different contexts. From a specific process that locally affects a quantity, to a formal framework that attempts to determine a global response to a forcing, researchers use this term to separate, simplify, and quantify parts of the complex Earth system. We combine large (>120 member) ensemble GCM and EMIC step forcing simulations over a broad range of forcing levels with a historical and educational perspective to organize existing ideas around feedbacks and linear forcing-feedback models. With a new method overcoming internal variability and initial condition problems we quantify the non-constancy of the climate feedback parameter. Our results suggest a strong state- and forcing-dependency of feedbacks, which is not considered appropriately in many studies. A non-constant feedback factor likely explains some of the differences in estimates of equilibrium climate sensitivity from different methods and types of data. We discuss implications for the definition of the forcing term and its various adjustments. Clarifying the value and applicability of the linear forcing feedback framework and a better quantification of feedbacks on various timescales and spatial scales remains a high priority in order to better understand past and predict future changes in the climate system.

  15. Feedback Linearization Controller for a Wind Energy Power System

    Directory of Open Access Journals (Sweden)

    Muthana Alrifai

    2016-09-01

    Full Text Available This paper deals with the control of a doubly-fed induction generator (DFIG-based variable speed wind turbine power system. A system of eight ordinary differential equations is used to model the wind energy conversion system. The generator has a wound rotor type with back-to-back three-phase power converter bridges between its rotor and the grid; it is modeled using the direct-quadrature rotating reference frame with aligned stator flux. An input-state feedback linearization controller is proposed for the wind energy power system. The controller guarantees that the states of the system track the desired states. Simulation results are presented to validate the proposed control scheme. Moreover, further simulation results are shown to investigate the robustness of the proposed control scheme to changes in some of the parameters of the system.

  16. A Selfish Linear Precoding Strategy for Downlink Two-User MIMO Systems Using Limited Rate Feedback

    Directory of Open Access Journals (Sweden)

    Lei Lv

    2013-07-01

    Full Text Available This letter proposes a limited feedback-based selfish linear precoding (SLP strategy for downlink two-user MIMO systems. In the proposed strategy, each user selfishly chooses the other user’s precoding matrix which minimizes its capacity loss. The proposed SLP strategy has two advantages comparing with traditional linear precoding strategies. First, SLP improves the system capacity by resisting interference more effectively. Second, the computing complexity of transmitter is reduced since the base station needs not to calculate precoding matrix. Simulation results verify the effectiveness of SLP on system capacity improvement comparing to limited feedback block diagonalization (LFBD algorithm, especially when feedback bits are insufficient.

  17. Arbitrarily low sensitivity (ALS) in linear distributed systems using pointwise linear feedback

    NARCIS (Netherlands)

    Kelemen, Matei; Kennai, Yakar; Horowitz, Isaac

    1990-01-01

    The sensitivity problem is defined for feedback systems with plants described by linear partial differential operators having constant coefficients, in a bounded one-dimensional domain. there are also finitely many observation points and finitely many lumped feedback loops, and a finite number of di

  18. Arbitrarily low sensitivity (ALS) in linear distributed systems using pointwise linear feedback

    NARCIS (Netherlands)

    Kelemen, Matei; Kennai, Yakar; Horowitz, Isaac

    1990-01-01

    The sensitivity problem is defined for feedback systems with plants described by linear partial differential operators having constant coefficients, in a bounded one-dimensional domain. there are also finitely many observation points and finitely many lumped feedback loops, and a finite number of

  19. Direct torque control with feedback linearization for induction motor drives

    DEFF Research Database (Denmark)

    Lascu, Cristian; Jafarzadeh, Saeed; Fadali, Sami M.

    2015-01-01

    This paper describes a Direct Torque Controlled (DTC) Induction Machine (IM) drive that employs feedback linearization and sliding-mode control. A feedback linearization approach is investigated, which yields a decoupled linear IM model with two state variables: torque and stator flux magnitude...... of the sliding surface. The VSC component assures robustness as in DTC, while the proportional component eliminates the torque and flux ripple. The torque time response is similar to DTC and the proposed solution is flexible and highly tunable due to the proportional controller. The controller design and its...... robust stability analysis are presented. The sliding controller is compared with a linear DTC scheme, and experimental results for a sensorless IM drive validate the proposed solution....

  20. Direct Torque Control With Feedback Linearization for Induction Motor Drives

    DEFF Research Database (Denmark)

    Lascu, Cristian Vaslie; Jafarzadeh, Saeed; Fadali, Sami M.

    2017-01-01

    This paper describes a direct-torque-controlled (DTC) induction motor (IM) drive that employs feedback linearization and sliding-mode control (SMC). A new feedback linearization approach is proposed, which yields a decoupled linear IM model with two state variables: torque and stator flux magnitude....... This intuitive linear model is used to implement a DTC-type controller that preserves all DTC advantages and eliminates its main drawback, the flux and torque ripple. Robust, fast, and ripple-free control is achieved by using SMC with proportional control in the vicinity of the sliding surface. SMC assures...... robustness as in DTC, while the proportional component eliminates the torque and flux ripple. The torque time response is similar to conventional DTC and the proposed solution is flexible and highly tunable due to the P component. The controller design is presented, and its robust stability is analyzed...

  1. Indirect Identification of Linear Stochastic Systems with Known Feedback Dynamics

    Science.gov (United States)

    Huang, Jen-Kuang; Hsiao, Min-Hung; Cox, David E.

    1996-01-01

    An algorithm is presented for identifying a state-space model of linear stochastic systems operating under known feedback controller. In this algorithm, only the reference input and output of closed-loop data are required. No feedback signal needs to be recorded. The overall closed-loop system dynamics is first identified. Then a recursive formulation is derived to compute the open-loop plant dynamics from the identified closed-loop system dynamics and known feedback controller dynamics. The controller can be a dynamic or constant-gain full-state feedback controller. Numerical simulations and test data of a highly unstable large-gap magnetic suspension system are presented to demonstrate the feasibility of this indirect identification method.

  2. A Result on Output Feedback Linear Quadratic Control

    NARCIS (Netherlands)

    Engwerda, J.C.; Weeren, A.J.T.M.

    2006-01-01

    In this note we consider the static output feedback linear quadratic control problem.We present both necessary and sufficient conditions under which this problem has a solution in case the involved cost depend only on the output and control variables.This result is used to present both necessary and

  3. Asymptotically optimal feedback control for a system of linear oscillators

    Science.gov (United States)

    Ovseevich, Alexander; Fedorov, Aleksey

    2013-12-01

    We consider problem of damping of an arbitrary number of linear oscillators under common bounded control. We are looking for a feedback control steering the system to the equilibrium. The obtained control is asymptotically optimal: the ratio of motion time to zero with this control to the minimum one is close to 1, if the initial energy of the system is large.

  4. Towards minimax policies for online linear optimization with bandit feedback

    CERN Document Server

    Bubeck, Sébastien; Kakade, Sham M

    2012-01-01

    We address the online linear optimization problem with bandit feedback. Our contribution is twofold. First, we provide an algorithm (based on exponential weights) with a regret of order $\\sqrt{d n \\log N}$ for any finite action set with $N$ actions, under the assumption that the instantaneous loss is bounded by 1. This shaves off an extraneous $\\sqrt{d}$ factor compared to previous works, and gives a regret bound of order $d \\sqrt{n \\log n}$ for any compact set of actions. Without further assumptions on the action set, this last bound is minimax optimal up to a logarithmic factor. Interestingly, our result also shows that the minimax regret for bandit linear optimization with expert advice in $d$ dimension is the same as for the basic $d$-armed bandit with expert advice. Our second contribution is to show how to use the Mirror Descent algorithm to obtain computationally efficient strategies with minimax optimal regret bounds in specific examples. More precisely we study two canonical action sets: the hypercub...

  5. Robust output feedback H-infinity control and filtering for uncertain linear systems

    CERN Document Server

    Chang, Xiao-Heng

    2014-01-01

    "Robust Output Feedback H-infinity Control and Filtering for Uncertain Linear Systems" discusses new and meaningful findings on robust output feedback H-infinity control and filtering for uncertain linear systems, presenting a number of useful and less conservative design results based on the linear matrix inequality (LMI) technique. Though primarily intended for graduate students in control and filtering, the book can also serve as a valuable reference work for researchers wishing to explore the area of robust H-infinity control and filtering of uncertain systems. Dr. Xiao-Heng Chang is a Professor at the College of Engineering, Bohai University, China.

  6. Observer design and output feedback stabilization for linear singular time-delay systems with unknown inputs

    Institute of Scientific and Technical Information of China (English)

    Peng CUI; Chenghui ZHANG

    2008-01-01

    The design of a functional observer and reduced-order observer with internal delay for linear singular timedelay systems with unknown inputs is discussed.The sufficient conditions of the existence of observers,which are normal linear time-delay systems,and the corresponding design steps are presented via linear matrix inequality(LMI).Moreover,the observer-based feedback stabilizing controller is obtained.Three examples are given to show the effectiveness of the proposed methods.

  7. Mutual Relations between Multiple-Input Linear and Multiple-Feedback

    Directory of Open Access Journals (Sweden)

    J. Horska

    2000-12-01

    Full Text Available State models of multiple-input linear non-autonomous dynamical systemsare modified to the autonomous form using a multiple piecewise-linear(PWL feedback. By such a way the corresponding state models of PWLautonomous dynamical system topologically conjugate to Lur'e systems[4] can be derived. As an example, the canonical state models ofmultiple-input linear and the corresponding multiple PWL feedbacksystems are proposed. Their state matrix equations and theintegrator-based circuit models are shown.

  8. Combined Sliding Mode Control with a Feedback Linearization for Speed Control of Induction Motor

    Directory of Open Access Journals (Sweden)

    Aamir Hashim Obeid Ahmed

    2011-06-01

    Full Text Available Induction Motor (IM speed control is an area of research that has been in prominence for some time now. In this paper, a nonlinear controller is presented for IM drives. The nonlinear controller is designed based on input-output feedback linearization control technique, combined with sliding mode control (SMC to obtain a robust, fast and precise control of IM speed. The input-output feedback linearization control decouples the flux control from the speed control and makes the synthesis of linear controllers possible. To validate the performances of the proposed control scheme, we provided a series of simulation results and a comparative study between the performances of the proposed control strategy and those of the feedback linearization control (FLC schemes. Simulation results show that the proposed control strategy scheme shows better performance than the FLC strategy in the face of system parameters variation

  9. State Feedback with Memory for Constrained Switched Positive Linear Systems

    Directory of Open Access Journals (Sweden)

    Jinjin Liu

    2015-04-01

    Full Text Available In this paper, the stabilization problem in switched linear systems with time-varying delay under constrained state and control is investigated. The synthesis of bounded state-feedback controllers with memory ensures that a closed-loop state is positive and stable. Firstly, synthesis with a sign-restricted (nonnegative and negative control is considered for general switched systems; then, the stabilization issue under bounded controls including the asymmetrically bounded controls and states constraints are addressed. In addition, the results are extended to systems with interval and polytopic uncertainties. All the proposed conditions are solvable in term of linear programming. Numerical examples illustrate the applicability of the results.

  10. Linear Feedback Analysis of Cardiovascular System using Seismocardiogram

    Directory of Open Access Journals (Sweden)

    Marcel Jiřina

    2005-01-01

    Full Text Available The paper deals with an analysis of relationship between heart rate described by a sequence of cardiac interbeat intervals and mechanical activity of heart represented by a sequence of systolic forces. Both the quantities were determined from seismocardiograms recorded from healthy subjects under two different experimental conditions. The method of the linear feedback baroreflex approach originally developed in [1], [2] and [3] was applied for the analysis. Different character of obtained results in comparison to those described in [1], [2] or [3], is explained by differences between frequency properties of the recorded sequences of the systolic forces and values of systolic blood pressure.

  11. A new hyperchaotic system and its linear feedback control

    Institute of Scientific and Technical Information of China (English)

    Cai Guo-Liang; Zheng-Song; TianLi-Xin

    2008-01-01

    This paper reports a new hyperchaotic system by adding an additional state variable into a three-dimensional chaotic dynamical system,studies some of its basic dynamical properties,such as the hyperchaotic attractor,Lyapunov exponents,bifurcation diagram and the hyperchaotic attractor evolving into periodic,quasi-periodic dynamical behaviours by varying parameter k.Furthermore,effective linear feedback control method is used to suppress hyperchaes to unstable equilibrium,periodic orbits and quasi-periodic orbits.Numerical simulations are presented to show these results.

  12. Feedback Linearization Controller Of The Delta WingRock Phenomena

    Directory of Open Access Journals (Sweden)

    Mohammed Alkandari

    2015-05-01

    Full Text Available This project deals with the control of the wing rock phenomena of a delta wing aircraft. a control schemeis proposed to stabilize the system. The controlleris a feedback linearization controller. It is shown that the proposed control scheme guarantee the asymptotic convergence to zero of all the states of the system. To illustrate the performance of the proposed controller, simulation results are presented and discussed. It is found that the proposed control scheme work well for the wing rock phenomena of a delta wing aircraft.

  13. Adaptive feedback linearization applied to steering of ships

    Directory of Open Access Journals (Sweden)

    Thor I. Fossen

    1993-10-01

    Full Text Available This paper describes the application of feedback linearization to automatic steering of ships. The flexibility of the design procedure allows the autopilot to be optimized for both course-keeping and course-changing manoeuvres. Direct adaptive versions of both the course-keeping and turning controller are derived. The advantages of the adaptive controllers are improved performance and reduced fuel consumption. The application of nonlinear control theory also allows the designer in a systematic manner to compensate for nonlinearities in the control design.

  14. Stabilizing equilibrium by linear feedback control for controlling chaos in Chen system

    Energy Technology Data Exchange (ETDEWEB)

    Costa, V A [Departamento de Ciencias Basicas, Facultad de IngenierIa (UNLP), La Plata (Argentina); Gonzalez, G A, E-mail: vacosta@ing.unlp.edu.ar, E-mail: ggonzal@fi.ub.ar [Departamento de Matematica, Facultad de Ingenieria (UBA), Buenos Aires (Argentina)

    2011-03-01

    Stabilization of a chaotic system in one of its unstable equilibrium points by applying small perturbations is studied. A two-stage control strategy based on linear feedback control is applied. Improvement of system performance is addressed by exploiting the ergodicity of the original dynamics and using Lyapunov stability results for control design. Extension to the not complete observability case is also analyzed.

  15. Design of bounded feedback controls for linear dynamical systems by using common Lyapunov functions

    Institute of Scientific and Technical Information of China (English)

    Igor; Ananievskii; Nickolai; Anokhin; Alexander; Ovseevich

    2011-01-01

    For a linear dynamical system,we address the problem of devising a bounded feedback control,which brings the system to the origin in finite time.The construction is based on the notion of a common Lyapunov function.It is shown that the constructed control remains effective in the presence of small perturbations.

  16. Model Predictive Control of PMSM Based on Feedback Linearization%基于反馈线性化的永磁同步电机模型预测控制

    Institute of Scientific and Technical Information of China (English)

    林辉; 王永宾; 计宏

    2011-01-01

    A control scheme with feedback linearization and model predictive control (MPC) for permanent magnet synchronous motor (PMSM) is presented. The necessary and sufficient conditions of feedback linearization of the non-linear PMSM model are discussed with differential geometry method and it is transformed into linear one. The principle of MPC and the treatment of system constraints are analyzed. The controllers are respectively designed for linear PMSM model with MPC and the method of state feedback pole assignment. In the case of constraint and unconstraint condition, the control effect of above-mentioned both schemes are compared. The simulation results show that the control method based on feedback linearization and MPC can simplify the design of the controller and reduce the error generated as the model mismatch; it can overcome the effect of constraints condition and ensure the ideal steady state and dynamic performance.%提出一种基于反馈线性化和模型预测控制(MPC)策略的永磁同步电机(PMSM)控制方案.运用微分几何理论讨论了非线性PMSM模型可进行反馈线性化的充分必要条件,并将其转换为新坐标空间中的线性模型;分析了MPC原理和对系统约束条件的处理方法.针对获得的PMSM线性模型,分别采用MPC和状态反馈极点配置方法设计了控制器.在有约束条件和无约束条件的情况下,对上述两种控制方法进行了控制效果比较.仿真实验结果表明,基于反馈线性化和MPC的控制方法可以简化系统的控制器设计,减小因模型失配而产生的误差;可以解决约束条件对系统性能的影响,保证系统具有理想的稳态和动态性能.

  17. Active vibration control for nonlinear vehicle suspension with actuator delay via I/O feedback linearization

    Science.gov (United States)

    Lei, Jing; Jiang, Zuo; Li, Ya-Li; Li, Wu-Xin

    2014-10-01

    The problem of nonlinear vibration control for active vehicle suspension systems with actuator delay is considered. Through feedback linearization, the open-loop nonlinearity is eliminated by the feedback nonlinear term. Based on the finite spectrum assignment, the quarter-car suspension system with actuator delay is converted into an equivalent delay-free one. The nonlinear control includes a linear feedback term, a feedforward compensator, and a control memory term, which can be derived from a Riccati equation and a Sylvester equation, so that the effects produced by the road disturbances and the actuator delay are compensated, respectively. A predictor is designed to implement the predictive state in the designed control. Moreover, a reduced-order observer is constructed to solve its physical unrealisability problem. The stability proofs for the zero dynamics and the closed-loop system are provided. Numerical simulations illustrate the effectiveness and the simplicity of the designed control.

  18. Chaotifying a stable linear controllable system by single input state feedback

    Institute of Scientific and Technical Information of China (English)

    Wu Zheng-Mao; Lu Jun-Guo; Xie Jian-Ying

    2007-01-01

    In this paper, an approach for chaotifying a stable controllable linear system via single input state-feedback is presented. The overflow function of the system states is designed as the feedback controller, which can make the fixed point of the closed-loop system to be a snap-back repeller, thereby yields chaotic dynamics. Based on the Marotto theorem, it proves theoretically that the closed-loop system is chaotic in the sense of Li and Yorke. Finally, the simulation results are used to illustrate the effectiveness of the proposed method.

  19. Optimal feedback control of linear quantum systems in the presence of thermal noise

    Science.gov (United States)

    Genoni, Marco G.; Mancini, Stefano; Serafini, Alessio

    2013-04-01

    We study the possibility of taking bosonic systems subject to quadratic Hamiltonians and a noisy thermal environment to nonclassical stationary states by feedback loops based on weak measurements and conditioned linear driving. We derive general analytical upper bounds for the single-mode squeezing and multimode entanglement at steady state, depending only on the Hamiltonian parameters and on the number of thermal excitations of the bath. Our findings show that, rather surprisingly, larger number of thermal excitations in the bath allow for larger steady-state squeezing and entanglement if the efficiency of the optimal continuous measurements conditioning the feedback loop is high enough. We also consider the performance of feedback strategies based on homodyne detection and show that, at variance with the optimal measurements, it degrades with increasing temperature.

  20. Robust model reference adaptive output feedback tracking for uncertain linear systems with actuator fault based on reinforced dead-zone modification.

    Science.gov (United States)

    Bagherpoor, H M; Salmasi, Farzad R

    2015-07-01

    In this paper, robust model reference adaptive tracking controllers are considered for Single-Input Single-Output (SISO) and Multi-Input Multi-Output (MIMO) linear systems containing modeling uncertainties, unknown additive disturbances and actuator fault. Two new lemmas are proposed for both SISO and MIMO, under which dead-zone modification rule is improved such that the tracking error for any reference signal tends to zero in such systems. In the conventional approach, adaption of the controller parameters is ceased inside the dead-zone region which results tracking error, while preserving the system stability. In the proposed scheme, control signal is reinforced with an additive term based on tracking error inside the dead-zone which results in full reference tracking. In addition, no Fault Detection and Diagnosis (FDD) unit is needed in the proposed approach. Closed loop system stability and zero tracking error are proved by considering a suitable Lyapunov functions candidate. It is shown that the proposed control approach can assure that all the signals of the close loop system are bounded in faulty conditions. Finally, validity and performance of the new schemes have been illustrated through numerical simulations of SISO and MIMO systems in the presence of actuator faults, modeling uncertainty and output disturbance.

  1. Dynamic output feedback linearizing control of saturated induction motors with torque per ampere ratio maximization

    OpenAIRE

    Peresada, Sergei; Kovbasa, Serhii; Dymko, Serhii; BOZHKO, Serhiy

    2016-01-01

    The paper presents a novel maximum torque per Ampere (MTA) controller for induction motor (IM) drives. The proposed controller exploits the concept of direct (observer based) field orientation and guarantees asymptotic torque tracking of smooth reference trajectories and maximizes the torque per Ampere ratio when the developed torque is constant or slowly varying. A dynamic output-feedback linearizing technique is employed for the torque subsystem design. In order to improve torque tracking a...

  2. Recovery of systems with a linear filter and nonlinear delay feedback in periodic regimes.

    Science.gov (United States)

    Ponomarenko, V I; Prokhorov, M D

    2008-12-01

    We propose a set of methods for the estimation of the parameters of time-delay systems with a linear filter and nonlinear delay feedback performing periodic oscillations. The methods are based on an analysis of the system response to regular external perturbations and are valid only for systems whose dynamics can be perturbed. The efficiency of the methods is illustrated using both numerical and experimental data.

  3. Self-Appraisal Based upon Supervisory Feedback.

    Science.gov (United States)

    Steel, Robert P.; Ovalle, Nestor K.

    1984-01-01

    Compared self-appraisals with instructions referencing supervisory feedback with conventional self-appraisals with personnel from a large institution (N=401) and two samples of military personnel (N=117). Results showed that Feedback Based Self Appraisals exhibited more agreement with superior ratings, and degree of feedback available moderated…

  4. Analysis and control for a new chaotic system via piecewise linear feedback

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jianxiong [Institute of Systems Engineering, Tianjin University, Tianjin 300072 (China)], E-mail: jxzhang@tju.edu.cn; Tang Wansheng [Institute of Systems Engineering, Tianjin University, Tianjin 300072 (China)

    2009-11-30

    This paper presents a new three-dimensional chaotic system containing two system parameters and a nonlinear term in the form of arc-hyperbolic sine function. The complicated dynamics are studied by virtue of theoretical analysis, numerical simulation and Lyapunov exponents spectrum. The system proposed is converted to an uncertain piecewise linear system. Then, based on piecewise quadratic Lyapunov function technique, the global control of the new chaotic system with {alpha}-stability constraint via piecewise linear state feedback is studied, where the optimal controller maximizing the decay rate {alpha} can be obtained by solving an optimization problem under bilinear matrix inequalities (BMIs) constraints.

  5. Application of non-linear discretetime feedback regulators with assignable closed-loop dynamics

    Directory of Open Access Journals (Sweden)

    Dubljević Stevan

    2003-01-01

    Full Text Available In the present work the application of a new approach is demonstrated to a discrete-time state feedback regulator synthesis with feedback linearization and pole-placement for non-linear discrete-time systems. Under the simultaneous implementation of a non-linear coordinate transformation and a non-linear state feedback law computed through the solution of a system of non-linear functional equations, both the feedback linearization and pole-placement design objectives were accomplished. The non-linear state feedback regulator synthesis method was applied to a continuous stirred tank reactor (CSTR under non-isothermal operating conditions that exhibits steady-state multiplicity. The control objective was to regulate the reactor at the middle unstable steady state by manipulating the rate of input heat in the reactor. Simulation studies were performed to evaluate the performance of the proposed non-linear state feedback regulator, as it was shown a non-linear state feedback regulator clearly outperformed a standard linear one, especially in the presence of adverse disturbance under which linear regulation at the unstable steady state was not feasible.

  6. Output regulation problem for discrete-time linear time-delay systems by output feedback control

    Institute of Scientific and Technical Information of China (English)

    Yamin YAN; Jie HUANG

    2016-01-01

    In this paper, we study the output regulation problem of discrete linear time-delay systems by output feedback control. We have established some results parallel to those for the output regulation problem of continuous linear time-delay systems.

  7. An Optimal Transport Formulation of the Linear Feedback Particle Filter

    OpenAIRE

    Taghvaei, Amirhossein; Mehta, Prashant G.

    2015-01-01

    Feedback particle filter (FPF) is an algorithm to numerically approximate the solution of the nonlinear filtering problem in continuous time. The algorithm implements a feedback control law for a system of particles such that the empirical distribution of particles approximates the posterior distribution. However, it has been noted in the literature that the feedback control law is not unique. To find a unique control law, the filtering task is formulated here as an optimal transportation pro...

  8. Linearization Techniques

    Directory of Open Access Journals (Sweden)

    Gildeberto S. Cardoso

    2011-01-01

    Full Text Available This paper presents a study of linear control systems based on exact feedback linearization and approximate feedback linearization. As exact feedback linearization is applied, a linear controller can perform the control objectives. The approximate feedback linearization is required when a nonlinear system presents a noninvolutive property. It uses a Taylor series expansion in order to compute a nonlinear transformation of coordinates to satisfy the involutivity conditions.

  9. Permanent Magnet Direct-driven Wind Power Generation System Based on Direct Feedback Linearization%基于直接反馈线性化的永磁直驱风力发电系统

    Institute of Scientific and Technical Information of China (English)

    童克诚; 孙赟

    2016-01-01

    Taking maximum wind energy capture below rated wind speed as a target,this paper uses direct feedback lineariza-tion theory to design wind power generation control system based on permanent magnetic synchronous generator (PMSG). On the simulation platform called power system computer aided design and electric magnetic transient in DC system (PSCAD/EMTDC),it establishes PMSG wind power generation unit model and carries out simulation analysis. Results indi-cate that the method of direct feedback linearization could effectively realize maximum wind energy capture of wind power generation unit and stable operation of the whole system which has stronger robustness.%针对永磁同步发电机(permanent magnet synchronous generator,PMSG),以额定风速以下风能最大捕获为目标,采用直接反馈线性化理论设计的风力发电控制系统,在电力系统计算机辅助设计和电磁暂态模拟程序软件(power system computer aided design and electric magnetic transient in DC system,PSCAD/EMTDC)仿真平台上建立 PMSG 风力发电机组模型并进行仿真分析,仿真结果表明,直接反馈线性化方法能够有效实现风力发电机组的最大风能捕获和整个系统的稳定运行,具有较强的鲁棒性。

  10. 基于状态反馈精确线性化变结构控制的SSSC控制器设计%Design of SSSC Controller Based on Exact Linearization Via Feedback and Variable-structure

    Institute of Scientific and Technical Information of China (English)

    邓大磊; 王奔; 尹维恒

    2013-01-01

    提出一种基于状态反馈精确线性化变结构控制的静止同步串联补偿器(SSSC)控制器设计方法.考虑到SSSC交流侧电压幅值和相角以及直流侧电容电压的动态调节过程,建立了SSSC在同步旋转dq坐标系下的非线性数学模型,在此模型的基础上,采用状态反馈精确线性化方法将原非线性系统转化为线性系统.然后,应用变结构控制原理设计SSSC控制器,同时通过PI控制稳定直流侧电容电压.最后,利用MATLAB仿真软件搭建了装设有SSSC的110kV输电系统的仿真模型,仿真结果表明了所设计的控制器能够很好地根据需求来改善电网输电能力,具有良好的暂态控制性能.%To improve the power grid transmission capacity with the static synchronous serier compensator (SSSC),a design method of SSSC controller based on exact linearization via feedback and variable structure control is proposed.By considering of the dynamic regulating process of the voltage magnitude and angle in the ac side of SSSC and the dynamic variable characteristics of the capacitance voltage in the dc side of SSSC,a nonlinear mathematical model of SSSC in synchronously rotating dq frame of coordinate system is built,based on which state feedback based exact linearization method is presented to convert the nonlinear mathematical model into the linear one.Then,the controller of SSSC is designed by using variable structure control theory,and DC capacity voltage is stabilized by PI control.In the end,the model of 110kV transmission system with SSSC is built by MATLAB for simulation and analysis.The simulation results show that the designed controllers can improve the power grid transmission capacity according to demand,which has good transient control performance.

  11. Static Output-Feedback Control for Vehicle Suspensions: A Single-Step Linear Matrix Inequality Approach

    Directory of Open Access Journals (Sweden)

    Josep Rubió-Massegú

    2013-01-01

    Full Text Available In this paper, a new strategy to design static output-feedback controllers for a class of vehicle suspension systems is presented. A theoretical background on recent advances in output-feedback control is first provided, which makes possible an effective synthesis of static output-feedback controllers by solving a single linear matrix inequality optimization problem. Next, a simplified model of a quarter-car suspension system is proposed, taking the ride comfort, suspension stroke, road holding ability, and control effort as the main performance criteria in the vehicle suspension design. The new approach is then used to design a static output-feedback H∞ controller that only uses the suspension deflection and the sprung mass velocity as feedback information. Numerical simulations indicate that, despite the restricted feedback information, this static output-feedback H∞ controller exhibits an excellent behavior in terms of both frequency and time responses, when compared with the corresponding state-feedback H∞ controller.

  12. Tests of the FONT3 Linear Collider Intra-Train Beam Feedback System at the ATF

    CERN Document Server

    Burrows, P N; Clarke, Christine; Frisch, Josef; Hartin, Anthony F; Kalinin, Alexander; Khah, H; Markiewicz, Thomas W; McCormick, Douglas; Molloy, Stephen; Perry, Colin; Ross, Marc; Smith, Stephen; Smith, Tonee; White, Glen

    2005-01-01

    We report preliminary results of beam tests of the FONT3 Linear Collider intra-train position feedback system prototype at the Accelerator Test Facility at KEK. The feedback system incorporates a novel beam position monitor (BPM) processor with a latency below 5 nanoseconds, and a kicker driver amplifier with similar low latency. The 56 nanosecond-long bunchtrain in the ATF extraction line was used to test the prototype with delay-loop feedback operation. The achieved latency represents a demonstration of intra-train feedback on timescales relevant even for the CLIC Linear Collider design.

  13. Feedback for Web-based Assignments.

    Science.gov (United States)

    Collis, Betty; De Boer, W.; Slotman, K.

    2001-01-01

    Discusses a concept used at the University of Twente based on increased flexibility in learning options and the active student in which there are assignments submitted and monitored via a Web-based course management system. Outlines conceptual aspects of feedback as part of the assessment process, particularly feedback supported by a Web-based…

  14. Nanosecond-Timescale Intra-Bunch-Train Feedback for the Linear Collider: Results of the FONT2 Run

    Energy Technology Data Exchange (ETDEWEB)

    Barlow, R.; Dufau, M.; Kalinin, A.; /Daresbury; Myatt, G.; Perry, C.; /Oxford U.; Burrows, P.N.; Hartin, T.; Hussain, S.M.; Molloy, S.; White, G.R.; /Queen Mary, U. of; Adolphsen, C.; Frisch, J.C.; Hendrickson, L.; Jobe, R.K.; Markiewicz, T.; McCormick, D.J.; Nelson, J.; Ross, M.C.; Smith, S.; Smith, T.J.; /SLAC

    2005-05-11

    We report on experimental results from the December 2003/January 2004 data run of the Feedback On Nanosecond Timescales (FONT) experiment at the Next Linear Collider Test Accelerator at SLAC. We built a second-generation prototype intra-train beam-based feedback system incorporating beam position monitors, fast analogue signal processors, a feedback circuit, fast-risetime amplifiers and stripline kickers. We applied a novel real-time charge-normalization scheme to account for beam current variations along the train. We used the system to correct the position of the 170-nanosecond-long bunchtrain at NLCTA. We achieved a latency of 53 nanoseconds, representing a significant improvement on FONT1 (2002), and providing a demonstration of intra-train feedback for the Linear Collider.

  15. MIMO Relaying Broadcast Channels with Linear Precoding and Quantized Channel State Information Feedback

    CERN Document Server

    Xu, Wei; Lu, Wu-Sheng; 10.1109/TSP.2010.2056687

    2012-01-01

    Multi-antenna relaying has emerged as a promising technology to enhance the system performance in cellular networks. However, when precoding techniques are utilized to obtain multi-antenna gains, the system generally requires channel state information (CSI) at the transmitters. We consider a linear precoding scheme in a MIMO relaying broadcast channel with quantized CSI feedback from both two-hop links. With this scheme, each remote user feeds back its quantized CSI to the relay, and the relay sends back the quantized precoding information to the base station (BS). An upper bound on the rate loss due to quantized channel knowledge is first characterized. Then, in order to maintain the rate loss within a predetermined gap for growing SNRs, a strategy of scaling quantization quality of both two-hop links is proposed. It is revealed that the numbers of feedback bits of both links should scale linearly with the transmit power at the relay, while only the bit number of feedback from the relay to the BS needs to gr...

  16. A numerical algorithm for optimal feedback gains in high dimensional linear quadratic regulator problems

    Science.gov (United States)

    Banks, H. T.; Ito, K.

    1991-01-01

    A hybrid method for computing the feedback gains in linear quadratic regulator problem is proposed. The method, which combines use of a Chandrasekhar type system with an iteration of the Newton-Kleinman form with variable acceleration parameter Smith schemes, is formulated to efficiently compute directly the feedback gains rather than solutions of an associated Riccati equation. The hybrid method is particularly appropriate when used with large dimensional systems such as those arising in approximating infinite-dimensional (distributed parameter) control systems (e.g., those governed by delay-differential and partial differential equations). Computational advantages of the proposed algorithm over the standard eigenvector (Potter, Laub-Schur) based techniques are discussed, and numerical evidence of the efficacy of these ideas is presented.

  17. Vibration state estimation of nonlinear suspension system based on feedback linearization%基于反馈线性化的非线性悬架系统振动状态观测

    Institute of Scientific and Technical Information of China (English)

    陈思忠; 卢凡; 吴志成; 杨林; 赵玉壮

    2015-01-01

    针对悬架系统非线性特性提出反馈线性化卡尔曼滤波算法。基于微分几何理论,通过求解坐标变换,将车辆非线性振动模型变换成可观测标准型,实现系统精确反馈线性化;采用线性卡尔曼滤波算法,针对变换的线性系统设计观测器,通过坐标逆变换获得原非线性系统的状态观测值。仿真结果表明,该算法能提高车辆振动状态观测精度、降低运算量。%Aiming at the nonlinearity of suspension system,a feedback linearization Kalman filter algorithm was proposed.Based on the differential geometry theory,the nonlinear vehicle vibration model was transformed into a certain observable normal form via the change of state coordinates.Based on the obtained linearized system,an observer was designed by using Kalman filter algorithm.Finally the estimated states of the nonlinear system were obtained through inverse transformation.The simulation results show that compared with the extended Kalman observer,the proposed algorithm can improve the observation accuracy of vehicle vibration states and reduce computational complexity.

  18. Cooperative linear output regulation for networked systems by dynamic measurement output feedback

    Science.gov (United States)

    Li, Shaobao; Feng, Gang; Wang, Juan; Luo, Xiaoyuan; Guan, Xinping

    2016-04-01

    This paper investigates the cooperative linear output regulation problem of a class of heterogeneous networked systems with a common reference input but with different disturbances for individual nodes. A novel distributed control law is presented based on dynamic measurement output feedback. It is shown that the overall networked closed-loop control system is asymptotically stable and the output regulation errors asymptotically approach zero as time goes to infinity under a sufficient and necessary condition. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed control law.

  19. Memory State Feedback RMPC for Multiple Time-Delayed Uncertain Linear Systems with Input Constraints

    Directory of Open Access Journals (Sweden)

    Wei-Wei Qin

    2014-01-01

    Full Text Available This paper focuses on the problem of asymptotic stabilization for a class of discrete-time multiple time-delayed uncertain linear systems with input constraints. Then, based on the predictive control principle of receding horizon optimization, a delayed state dependent quadratic function is considered for incorporating MPC problem formulation. By developing a memory state feedback controller, the information of the delayed plant states can be taken into full consideration. The MPC problem is formulated to minimize the upper bound of infinite horizon cost that satisfies the sufficient conditions. Then, based on the Lyapunov-Krasovskii function, a delay-dependent sufficient condition in terms of linear matrix inequality (LMI can be derived to design a robust MPC algorithm. Finally, the digital simulation results prove availability of the proposed method.

  20. Nonlinear robust control of proton exchange membrane fuel cell by state feedback exact linearization

    Energy Technology Data Exchange (ETDEWEB)

    Li, Q.; Chen, W. [School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan Province (China); Wang, Y.; Jia, J. [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue 639798, Singapore (Singapore); Han, M. [School of Engineering, Temasek Polytechnic, Tampines 529757, Singapore (Singapore)

    2009-10-20

    By utilizing the state feedback exact linearization approach, a nonlinear robust control strategy is designed based on a multiple-input multiple-output (MIMO) dynamic nonlinear model of proton exchange membrane fuel cell (PEMFC). The state feedback exact linearization approach can achieve the global exact linearization via the nonlinear coordinate transformation and the dynamic extension algorithm such that H{sub {infinity}} robust control strategy can be directly utilized to guarantee the robustness of the system. The proposed dynamic nonlinear model is tested by comparing the simulation results with the experimental data in Fuel Cell Application Centre in Temasek Polytechnic. The comprehensive results of simulation manifest that the dynamic nonlinear model with nonlinear robust control law has better transient and robust stability when the vehicle running process is simulated. The proposed nonlinear robust controller will be very useful to protect the membrane damage by keeping the pressure deviations as small as possible during large disturbances and prolong the stack life of PEMFC. (author)

  1. Application of Feedback Linearization Method in Airplane Automatic Landing Control System

    Institute of Scientific and Technical Information of China (English)

    Wang Xiaoyan; Feng Jiang; Feng Xiujuan; Wu Junqin

    2004-01-01

    Summarizes the I/O feedback linearization about MIMO system, and applies it to nonlinear control equation of airplane. And also designs the tracing control laws for airplane longitudinal automatic landing control system.

  2. Roll Damping Control of Marine Robot Near-surface Based on Dynamic Feedback Linearization%基于动态反馈线性化的海洋机器人近水面横摇减摇控制

    Institute of Scientific and Technical Information of China (English)

    金鸿章; 高妍南; 周生彬

    2012-01-01

    As marine robot navigating with low speed near surface, it has wiling motion caused by the disturbance of wave, which seriously influence its security and performance. Therefore, the zero-speed fin stabilizer system is applied to control the rolling motion. Based on the marine robot's dynamic properties and the features of the lift model of the zero speed fin stabilizer, a roll damping law is developed by using the approach of dynamic feedback linearization. The original system is extended to a new system with apseudostate variable and the system linearization is realized. The problem of the system's nonlinear input caused by the lift model of fin stabilizer is resolved. The theoretical proof and the simulation result show that the controller is stable and effective.%海洋机器人在近水面低速航行时,在海浪干扰下将产生横摇运动,严重影响机器人安全性能,因此利用零航速减摇鳍系统对横摇运动加以有效控制.针对机器人非线性运动模型及零航速减摇鳍升力模型的特点,利用动态反馈线性化方法设计横摇减摇控制规律.该方法通过将原系统扩展为含有伪状态变量的新系统,实现系统线性化,解决由减摇鳍升力模型引起的系统非线性形式控制输入的问题.理论证明及仿真结果表明该横摇控制规律是稳定有效的.

  3. Decentralized-feedback pole placement of linear systems

    Science.gov (United States)

    Wang, X.; Martin, C. F.; Gilliam, D.; Byrnes, C. I.

    1992-01-01

    A projectile product spaces model is used to analyze decentralized systems. The degree of the pole placement map is computed. The conditions under which the degree is odd are also given. Twin lift systems are studied. It is proved that the poles of a twin lift system can be assigned to any values by local static and local dynamic feedback laws if and only if the system is jointly controllable.

  4. DEVELOPMENT OF A FAST MICRON-RESOLUTION BEAM POSITION MONITOR SIGNAL PROCESSOR FOR LINEAR COLLIDER BEAMBASED FEEDBACK SYSTEMS

    CERN Document Server

    Apsimon, R; Clarke, C; Constance, B; Dabiri Khah, H; Hartin, T; Perry, C; Resta Lopez, J; Swinson, C; Christian, G B; Kalinin, A

    2009-01-01

    We present the design of a prototype fast beam position monitor (BPM) signal processor for use in inter-bunch beam-based feedbacks for linear colliders and electron linacs. We describe the FONT4 intra-train beam-based digital position feedback system prototype deployed at the Accelerator test facility (ATF) extraction line at KEK, Japan. The system incorporates a fast analogue beam position monitor front-end signal processor, a digital feedback board, and a fast kicker-driver amplifier. The total feedback system latency is less than 150ns, of which less than 10ns is used for the BPM processor. We report preliminary results of beam tests using electron bunches separated by c. 150ns. Position resolution of order 1 micron was obtained.

  5. An adaptive feedback linearization strategy for variable speed wind energy conversion systems

    Energy Technology Data Exchange (ETDEWEB)

    Valenciaga, F.; Puleston, P.F.; Battaiotto, P.E.; Mantz, R.J. [Universidad Nacional de La Plata, Depto. de Electrotecnia, La Plata (Argentina)

    2000-07-01

    This paper presents a control strategy based on adaptive feedback linearization intended for variable speed grid-connected wind energy conversion systems (WECS). The proposed adaptive control law accomplishes energy capture maximization by tracking the wind speed fluctuations. In addition, it linearizes the system even in the presence of turbine model uncertainties, allowing the closed-loop dynamic behaviour to be determined by a simple tuning of the controller parameters. Particularly, the attention is focused on WECS with slip power recovery, which use a power conversion stage as a rotor-controlled double-output induction generator. However, the concepts behind the proposed control strategy are general and can be easily extended to other WECS configurations. (Author)

  6. Tests of the FONT3 Linear Collider Intra-Train Beam Feedback System at the ATF

    Energy Technology Data Exchange (ETDEWEB)

    Burrows, P.N.; Christian, G.; Clarke, C.; Hartin, A.; Dabiri Khah, H.; Molloy, S.; White, G.R.; /Queen Mary, U. of London; Frisch, J.C.; Markiewicz, T.W.; McCormick, D.J.; Ross, M.C.; Smith, S.; Smith, T.J.; /SLAC; Kalinin, A.; /Daresbury; Perry, C.; /Oxford Instruments

    2006-03-14

    We report preliminary results of beam tests of the FONT3 Linear Collider intra-train position feedback system prototype at the Accelerator Test Facility at KEK. The feedback system incorporates a novel beam position monitor (BPM) processor with a latency below 5 nanoseconds, and a kicker driver amplifier with similar low latency. The 56 nanosecond-long bunchtrain in the ATF extraction line was used to test the prototype BPM processor. The achieved latency will allow a demonstration of intra-train feedback on timescales relevant even for the CLIC Linear Collider design.

  7. Tranceiver Design using Linear Precoding in a Multiuser MIMO System with Limited Feedback

    CERN Document Server

    Islam, Muhammad Nazmul

    2010-01-01

    We investigate quantization and feedback of channel state information in a multiuser (MU) multiple input multiple output (MIMO) system. Each user may receive multiple data streams. Our design minimizes the sum mean squared error (SMSE) while accounting for the imperfections in channel state information (CSI) at the transmitter. This paper makes three contributions: first, we provide an end-to-end SMSE transceiver design that incorporates receiver combining, feedback policy and transmit precoder design with channel uncertainty. This enables the proposed transceiver to outperform the previously derived limited feedback MU linear transceivers. Second, we remove dimensionality constraints on the MIMO system, for the scenario with multiple data streams per user, using a combination of maximum expected signal combining (MESC) and minimum MSE receiver. This makes the feedback of each user independent of the others and the resulting feedback overhead scales linearly with the number of data streams instead of the numb...

  8. Carrier-based aircraft steam catapult system with feedback linearization control%舰载机蒸汽弹射反馈线性控制系统研究

    Institute of Scientific and Technical Information of China (English)

    刘恒; 朱齐丹; 李晓琳; 董然

    2016-01-01

    To study the states'change of accumulator and cylinder in steam catapult aircraft launch, aiming at the nonlinear coupling characteristics of the cylinder system, considering the flashing phenomenon in the steam accu⁃mulator, the pressure change of chamber with rod and without rod in the steam cylinder, and the relationship be⁃tween launching valve's core displacement and flow area, the steam accumulator and launching valve mathematical model, cylinder thermodynamic model and the aircraft six degrees of freedom dynamics model were established, and the launching valve controller of steam catapult system was accomplished. The simulation finds that the pres⁃sure⁃drop steam catapult system was extremely small, almost negligible in the catapult period; moreover, because of the nonlinear and coupling characteristics of the cylinder system, the traditional control method cannot accom⁃plish a stable launching valve, whose opening degree experiences strong mutations when opened and closed. Based on the feedback linearization theory, the steam cylinder model can be completely linearized and can decouple cylin⁃der state variables, contributing to the design of the launching valve controller. The simulation shows that using the feedback linearization method, the launching valve regulator can perform in a stable manner, achieving acceptable acceleration tracking effect during the catapult process.%为了研究舰载机蒸汽弹射过程中储汽筒与汽缸中各状态的变化,针对汽缸系统的非线性强耦合特点,考虑储汽筒内闪蒸现象、汽缸有杆腔与无杆腔压力变化以及发射阀芯位移与流通面积之间的关系,建立储汽筒、发射阀的数学模型,汽缸的热力学模型以及舰载机的六自由度运动模型,完成蒸汽弹射系统发射阀控制器设计。通过仿真研究发现,蒸汽弹射系统的储汽筒在弹射阶段压降很小,其影响可以忽略;并且,由于汽缸系统的各状态

  9. Non-linear feedback neural networks VLSI implementations and applications

    CERN Document Server

    Ansari, Mohd Samar

    2014-01-01

    This book aims to present a viable alternative to the Hopfield Neural Network (HNN) model for analog computation. It is well known that the standard HNN suffers from problems of convergence to local minima, and requirement of a large number of neurons and synaptic weights. Therefore, improved solutions are needed. The non-linear synapse neural network (NoSyNN) is one such possibility and is discussed in detail in this book. This book also discusses the applications in computationally intensive tasks like graph coloring, ranking, and linear as well as quadratic programming. The material in the book is useful to students, researchers and academician working in the area of analog computation.

  10. A Fully Differential Interface Circuit of Closed-loop Accelerometer with Force Feedback Linearization

    Institute of Scientific and Technical Information of China (English)

    HongLin Xu; HongNa Liu; Chong He; Liang Yin; XiaoWei Liu

    2014-01-01

    In this paper, a fifth-order fully differential interface circuit ( IC) is presented to improve the noise performance for micromechanical sigma-delta (Σ-Δ) accelerometer. A lead compensator is adopted to ensure the stability of the closed-loop high-order system. A low noise capacitance detection circuit is described with a correlated-double-sampling ( CDS) technique to decrease 1/f noise and offset of the operational amplifier. This paper also proposes a self-test technique for the interface circuit to test the harmonic distortion. An electrostatic force feedback linearization circuit is presented to reduce the harmonic distortion resulting in larger dynamic range ( DR) . The layout of the IC is implemented in a standard 0�6 μm CMOS technology and operates at a sampling frequency of 250 kHz. The interface consumes 20 mW from a 5 V supply. The post-simulation results indicate that the noise floor of the digital accelerometer is about -140 dBV/Hz1/2 at low frequency. The sensitivity is 2.5 V/g and the nonlinearity is 0�11%. The self-test function is achieved with 98�2 dB third-order harmonic distortion detection based on the electrostatic force feedback linearization.

  11. Luminosity performance studies of the compact linear collider with intra-train feedback system at the interaction point

    Energy Technology Data Exchange (ETDEWEB)

    Resta-Lopez, J; Burrows, P N; Christian, G, E-mail: j.restalopez@physics.ox.ac.u [John Adams Institute for Accelerator Science, Oxford University, Oxford, OX1 3RH (United Kingdom)

    2010-09-15

    To achieve the design luminosity at future linear colliders, control of beam stability at the sub-nanometre level at the interaction point will be necessary. Any source of beam motion which results in relative vertical offsets of the two beams at the interaction point may significantly reduce the luminosity from the nominal value. Beam-based intra-train feedback systems located in the interaction region are foreseen to correct the relative beam-beam offset and thus to steer the two beams into collision. These feedback systems must be capable of acting within the bunch train. In addition, these feedback systems might considerably help to relax the tight stability tolerances required for the final doublet magnets. For the Compact Linear Collider (CLIC), the extremely short nominal bunch spacing (0.5 ns) and very short nominal pulse duration (156 ns) make the intra-train feedback implementation technically very challenging. In this paper the conceptual design of an intra-train feedback system for the CLIC interaction point is described. Results of luminosity performance simulations are presented and discussed for different scenarios of ground motion. We also show how the intra-train feedback system can help to relax the very tight tolerances of the vertical vibration on the CLIC final doublet quadrupoles.

  12. Direct torque control via feedback linearization for permanent magnet synchronous motor drives

    DEFF Research Database (Denmark)

    Lascu, Cristian; Boldea, Ion; Blaabjerg, Frede

    2012-01-01

    The paper describes a direct torque controlled (DTC) permanent magnet synchronous motor (PMSM) drive that employs feedback linearization and uses sliding-mode and linear controllers. We introduce a new feedback linearization approach that yields a decoupled linear PMSM model with two state...... variables, the torque and the square of stator flux magnitude. This linear model is intuitive and allows the implementation of DTC-type controllers that preserve all DTC advantages and eliminate its main drawback, the flux and torque ripple. Next, we investigate two controllers for toque and flux....... A variable structure controller (VSC) which is robust, fast, and produces low-ripple control is compared with a linear-DTC scheme which is ripple free. The torque time response is similar to a conventional DTC drive and the proposed solutions are flexible and highly tunable. We present the controller design...

  13. Output feedback model matching in linear impulsive systems with control feedthrough: a structural approach

    Science.gov (United States)

    Zattoni, Elena

    2017-01-01

    This paper investigates the problem of structural model matching by output feedback in linear impulsive systems with control feedthrough. Namely, given a linear impulsive plant, possibly featuring an algebraic link from the control input to the output, and given a linear impulsive model, the problem consists in finding a linear impulsive regulator that achieves exact matching between the respective forced responses of the linear impulsive plant and of the linear impulsive model, for all the admissible input functions and all the admissible sequences of jump times, by means of a dynamic feedback of the plant output. The problem solvability is characterized by a necessary and sufficient condition. The regulator synthesis is outlined through the proof of sufficiency, which is constructive.

  14. Feedback control linear, nonlinear and robust techniques and design with industrial applications

    CERN Document Server

    Dodds, Stephen J

    2015-01-01

    This book develops the understanding and skills needed to be able to tackle original control problems. The general approach to a given control problem is to try the simplest tentative solution first and, when this is insufficient, to explain why and use a more sophisticated alternative to remedy the deficiency and achieve satisfactory performance. This pattern of working gives readers a full understanding of different controllers and teaches them to make an informed choice between traditional controllers and more advanced modern alternatives in meeting the needs of a particular plant. Attention is focused on the time domain, covering model-based linear and nonlinear forms of control together with robust control based on sliding modes and the use of state observers such as disturbance estimation. Feedback Control is self-contained, paying much attention to explanations of underlying concepts, with detailed mathematical derivations being employed where necessary. Ample use is made of diagrams to aid these conce...

  15. Control of uncertain systems by feedback linearization with neural networks augmentation. Part II. Controller validation by numerical simulation

    Directory of Open Access Journals (Sweden)

    Adrian TOADER

    2010-09-01

    Full Text Available The paper was conceived in two parts. Part I, previously published in this journal, highlighted the main steps of adaptive output feedback control for non-affine uncertain systems, having a known relative degree. The main paradigm of this approach was the feedback linearization (dynamic inversion with neural network augmentation. Meanwhile, based on new contributions of the authors, a new paradigm, that of robust servomechanism problem solution, has been added to the controller architecture. The current Part II of the paper presents the validation of the controller hereby obtained by using the longitudinal channel of a hovering VTOL-type aircraft as mathematical model.

  16. Novel fuzzy feedback linearization strategy for control via differential geometry approach.

    Science.gov (United States)

    Li, Tzuu-Hseng S; Huang, Chiou-Jye; Chen, Chung-Cheng

    2010-07-01

    The study investigates a novel fuzzy feedback linearization strategy for control. The main contributions of this study are to construct a control strategy such that the resulting closed-loop system is valid for any initial condition with almost disturbance decoupling performance, and develop the feedback linearization design for some class of nonlinear control systems. The feedback linearization control guarantees the almost disturbance decoupling performance and the uniform ultimate bounded stability of the tracking error system. Once the tracking errors are driven to touch the global final attractor with the desired radius, the fuzzy logic control is immediately applied via a human expert's knowledge to improve the convergence rate. One example, which cannot be solved by the first paper on the almost disturbance decoupling problem, is proposed in this paper to exploit the fact that the almost disturbance decoupling and the convergence rate performances are easily achieved by the proposed approach.

  17. Observer-based H-infinity output feedback control with feedback gain and observer gain variations for Delta operator system

    Institute of Scientific and Technical Information of China (English)

    Ruiquan LIN; Fuwen YANG; Renchong PENG

    2009-01-01

    Considering that the controller feedback gain and the observer gain are of additive norm-bounded variations, a design method of observer-based H-infinity output feedback controller for uncertain Delta operator systems is proposed in this paper. A sufficient condition of such controllers is presented in linear matrix inequality (LMI) forms. A numerical example is then given to illustrate the effectiveness of this method, that is, the obtained controller guarantees the closed-loop system asymptotically stable and the expected H-infinity performance even if the controller feedback gain and the observer gain are varied.

  18. Mitigation of ground motion effects via feedback systems in the Compact Linear Collider

    CERN Document Server

    Pfingstner, Jürgen; Schmickler, Hermann; Schulte, Daniel

    The Compact Linear Collider (CLIC) is a future multi-TeV electron positron collider, which is currently being designed at CERN. To achieve its ambitious goals, CLIC has to produce particle beams of the highest quality, which makes the accelerator very sensitive to ground motion. Four mitigation methods have been foreseen by the CLIC design group to cope with the feasibility issue of ground motion. This thesis is concerned with the design of one of these mitigation methods, named linac feedback (L-FB), but also with the simultaneous simulation and validation of all mitigation methods. Additionally, a technique to improve the quality of the indispensable system knowledge has been developed. The L-FB suppresses beam oscillations along the accelerator. Its design is based on the decoupling of the overall accelerator system into independent channels. For each channel an individual compensator is found with the help of a semi- automatic control synthesis procedure. This technique allows the designer to incorporate ...

  19. Stability of PID-Controlled Linear Time-Delay Feedback Systems

    CERN Document Server

    Martelli, Gianpasquale

    2008-01-01

    The stability of feedback systems consisting of linear time-delay plants and PID controllers has been investigated for many years by means of several methods, of which the Nyquist criterion, a generalization of the Hermite-Biehler Theorem, and the root location method are well known. The main purpose of these researches is to determine the range of controller parameters that allow stability. Explicit and complete expressions of the boundaries of these regions and computation procedures with a finite number of steps are now available only for first-order plants, provided with one time delay. In this note, the same results, based on Pontryagin's studies, are presented for arbitrary-order plants.

  20. Helicity coherence in binary neutron star mergers and non-linear feedback

    CERN Document Server

    Chatelain, Amélie

    2016-01-01

    Neutrino flavor conversion studies based on astrophysical environments usually implement neutrino mixings, neutrino interactions with matter and neutrino self-interactions. In anisotropic media, the most general mean-field treatment includes neutrino mass contributions as well, that introduce a coupling between neutrinos and antineutrinos termed helicity or spin coherence. We discuss resonance conditions for helicity coherence for Dirac and Majorana neutrinos. We explore the role of these mean-field contributions on flavor evolution in the context of a binary neutron star merger remnant. We find that resonance conditions can be satisfied in neutron star merger scenarios while adiabaticity is not sufficient for efficient flavor conversion. We analyse our numerical findings by discussing general conditions to have multiple MSW-like resonances, in presence of non-linear feedback, in astrophysical environments.

  1. Direct and Indirect Couplings in Coherent Feedback Control of Linear Quantum Systems

    CERN Document Server

    Zhang, Guofeng

    2010-01-01

    The purpose of this paper is to study and design direct and indirect couplings for use in coherent feedback control of a class of linear quantum stochastic systems. A general physical model for a nominal linear quantum system coupled directly and indirectly to external systems is presented. Fundamental properties of stability, dissipation, passivity, and gain for this class of linear quantum models are presented and characterized using complex Lyapunov equations and linear matrix inequalities (LMIs). Coherent $H^\\infty$ and LQG synthesis methods are extended to accommodate direct couplings using multistep optimization. Examples are given to illustrate the results.

  2. Distributed Cooperative Secondary Control of Microgrids Using Feedback Linearization

    DEFF Research Database (Denmark)

    Bidram, Ali; Davoudi, Ali; Lewis, Frank;

    2013-01-01

    This paper proposes a secondary voltage control of microgrids based on the distributed cooperative control of multi-agent systems. The proposed secondary control is fully distributed; each distributed generator (DG) only requires its own information and the information of some neighbors...

  3. Feedback.

    Science.gov (United States)

    Richardson, Barbara K

    2004-12-01

    The emergency department provides a rich environment for diverse patient encounters, rapid clinical decision making, and opportunities to hone procedural skills. Well-prepared faculty can utilize this environment to teach residents and medical students and gain institutional recognition for their incomparable role and teamwork. Giving effective feedback is an essential skill for all teaching faculty. Feedback is ongoing appraisal of performance based on direct observation aimed at changing or sustaining a behavior. Tips from the literature and the author's experience are reviewed to provide formats for feedback, review of objectives, and elements of professionalism and how to deal with poorly performing students. Although the following examples pertain to medical student education, these techniques are applicable to the education of all adult learners, including residents and colleagues. Specific examples of redirection and reflection are offered, and pitfalls are reviewed. Suggestions for streamlining verbal and written feedback and obtaining feedback from others in a fast-paced environment are given. Ideas for further individual and group faculty development are presented.

  4. Multivariable control of the Space Shuttle Remote Manipulator System using linearization by state feedback

    Science.gov (United States)

    Gettman, Chang-Ching L.; Adams, Neil; Bedrossian, Nazareth; Valavani, Lena

    1993-01-01

    This paper demonstrates an approach to nonlinear control system design that uses linearization by state feedback to allow faster maneuvering of payloads by the Shuttle Remote Manipulator System (SRMS). A nonlinear feedback law is defined to cancel the nonlinear plant dynamics so that a linear controller can be designed for the SRMS. First a nonlinear design model was generated via SIMULINK. This design model included nonlinear arm dynamics derived from the Lagrangian approach, linearized servo model, and linearized gearbox model. The current SRMS position hold controller was implemented on this system. Next, a trajectory was defined using a rigid body kinematics SRMS tool, KRMS. The maneuver was simulated. Finally, higher bandwidth controllers were developed. Results of the new controllers were compared with the existing SRMS automatic control modes for the Space Station Freedom Mission Build 4 Payload extended on the SRMS.

  5. Global chaos synchronization of the parametrically excited Duffing oscillators by linear state error feedback control

    Energy Technology Data Exchange (ETDEWEB)

    Wu Xiaofeng [Center for Control and Optimizations, South China University of Technology, Guangzhou 510640 (China) and Guangzhou Naval Academy, Guangzhou 510430 (China)], E-mail: wuxiaof@21cn.com; Cai Jianping [Department of Applied Mechanics and Engineering, Zhongshan University, Guangzhou 510275 (China); Wang Muhong [Guangzhou Naval Academy, Guangzhou 510430 (China)

    2008-04-15

    The paper deals with a linear state error feedback control technique which is utilized to synchronize two parametrically excited non-autonomous Duffing oscillators. Some sufficient criteria for global chaos synchronization are obtained by means of Lyapunov's direct method. A few examples are illustrated to verify the proposed theoretical results.

  6. The Optimal Linear Quadratic Feedback State Regulator Problem for Index One Descriptor Systems

    NARCIS (Netherlands)

    Engwerda, J.C.; Salmah, Y.; Wijayanti, I.E.

    2008-01-01

    In this note we present both necessary and sufficient conditions for the existence of a linear static state feedback controller if the system is described by an index one descriptor system. A priori no definiteness restrictions are made w.r.t. the quadratic performance criterium. It is shown that in

  7. Theory and Applications of Discontinuous State Feedback Generating Chaos for Linear Systems

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-Dan; WANG Zhen; ZHAO Pin-Dong

    2008-01-01

    We investigate a kind of chaos generating technique on a type of n-dimensional linear differential systems by adding feedback control items under a discontinuous state.This method is checked with some examples of numeric simulation.A constructive theorem is proposed for generalized synchronization related to the above chaotic system.

  8. Stabilization of sandwich non-linear systems with low-and-high gain feedback design

    NARCIS (Netherlands)

    Stoorvogel, Anton A.; Wang, Xu; Saberi, Ali; Sannuti, Peddapullaiah

    2010-01-01

    In this paper, we consider the problems of semi- global and global internal stabilization of a class of sandwich systems consisting of two linear systems with a saturation element in between. We develop here low-and-high gain and scheduled low-and-high gain state feedback design methodolo- gies to s

  9. Non-linear feedback control of the p53 protein-mdm2 inhibitor system using the derivative-free non-linear Kalman filter.

    Science.gov (United States)

    Rigatos, Gerasimos G

    2016-06-01

    It is proven that the model of the p53-mdm2 protein synthesis loop is a differentially flat one and using a diffeomorphism (change of state variables) that is proposed by differential flatness theory it is shown that the protein synthesis model can be transformed into the canonical (Brunovsky) form. This enables the design of a feedback control law that maintains the concentration of the p53 protein at the desirable levels. To estimate the non-measurable elements of the state vector describing the p53-mdm2 system dynamics, the derivative-free non-linear Kalman filter is used. Moreover, to compensate for modelling uncertainties and external disturbances that affect the p53-mdm2 system, the derivative-free non-linear Kalman filter is re-designed as a disturbance observer. The derivative-free non-linear Kalman filter consists of the Kalman filter recursion applied on the linearised equivalent of the protein synthesis model together with an inverse transformation based on differential flatness theory that enables to retrieve estimates for the state variables of the initial non-linear model. The proposed non-linear feedback control and perturbations compensation method for the p53-mdm2 system can result in more efficient chemotherapy schemes where the infusion of medication will be better administered.

  10. A New Approach to Dynamic Control of Synchronous Generator in a Bulk Electric Power System by Direct Feedback Linearization

    Directory of Open Access Journals (Sweden)

    S. Sajedi

    2011-11-01

    Full Text Available Feedback linearization is a common approach used in controlling nonlinear systems. The approach involves coming up with a transformation of the nonlinear system into an equivalent linear system through a change of variables and a suitable control input. In this paper a new control structure based on the application of the method of exact linearization by Direct Feedback Linearization for a synchronous generator is presented. The power system model consists of a single axis flat rotor machine, connected to an infinite power bus. This way the sub-transient phenomena are ignored. The global system consisting of a turbine and a generator that produces the electrical output power is coupled and it presents multiplicative and harmonic non-linearities. The application of a DFL on the output voltage equation expressed as a function of the electrical system parameters referred to the generator practically turns the non linear system into two uncoupled subsystems with the possibility of independently controlling the output voltage and the frequency.

  11. Stability and Performance of First-Order Linear Time-Delay Feedback Systems: An Eigenvalue Approach

    Directory of Open Access Journals (Sweden)

    Shu-An He

    2011-01-01

    Full Text Available Linear time-delay systems with transcendental characteristic equations have infinitely many eigenvalues which are generally hard to compute completely. However, the spectrum of first-order linear time-delay systems can be analyzed with the Lambert function. This paper studies the stability and state feedback stabilization of first-order linear time-delay system in detail via the Lambert function. The main issues concerned are the rightmost eigenvalue locations, stability robustness with respect to delay time, and the response performance of the closed-loop system. Examples and simulations are presented to illustrate the analysis results.

  12. Stress reduces use of negative feedback in a feedback-based learning task.

    Science.gov (United States)

    Petzold, Antje; Plessow, Franziska; Goschke, Thomas; Kirschbaum, Clemens

    2010-04-01

    In contrast to the well-established effects of stress on learning of declarative material, much less is known about stress effects on reward- or feedback-based learning. Differential effects on positive and negative feedback especially have received little attention. The objective of this study, thus, was to investigate effects of psychosocial stress on feedback-based learning with a particular focus on the use of negative and positive feedback during learning. Participants completed a probabilistic selection task in both a stress and a control condition. The task allowed quantification of how much participants relied on positive and negative feedback during learning. Although stress had no effect on general acquisition of the task, results indicate that participants used negative feedback significantly less during learning after stress compared with the control condition. An enhancing effect of stress on use of positive feedback failed to reach significance. These findings suggest that stress acts differentially on the use of positive and negative feedback during learning.

  13. Effects of Web-Based Feedback on Students' Learning

    Science.gov (United States)

    van Kol, Simone; Rietz, Christian

    2016-01-01

    Feedback plays an important role in supporting students' learning process. Nonetheless, providing feedback is still rather unusual in higher education. Moreover, research on the design of ideal feedback as well as its effects is rare. In order to contribute to the development of this field, a web-based feedback system was implemented in a lecture…

  14. Finite-time quantised feedback asynchronously switched control of sampled-data switched linear systems

    Science.gov (United States)

    Wang, Ronghao; Xing, Jianchun; Li, Juelong; Xiang, Zhengrong

    2016-10-01

    This paper studies the problem of stabilising a sampled-data switched linear system by quantised feedback asynchronously switched controllers. The idea of a quantised feedback asynchronously switched control strategy originates in earlier work reflecting actual system characteristic of switching and quantising, respectively. A quantised scheme is designed depending on switching time using dynamic quantiser. When sampling time, system switching time and controller switching time are all not uniform, the proposed switching controllers guarantee the system to be finite-time stable by a piecewise Lyapunov function and the average dwell-time method. Simulation examples are provided to show the effectiveness of the developed results.

  15. Further results on saturated globally stabilizing linear state feedback control laws for single-input neutrally stable planar systems

    NARCIS (Netherlands)

    Yang, Tao; Stoorvogel, Anton A.; Saberi, Ali; Johansson, Karl H.

    2013-01-01

    It is known that for single-input neutrally stable planar systems, there exists a class of saturated globally stabilizing linear state feedback control laws. The goal of this paper is to characterize the dynamic behavior for such a system under arbitrary locally stabilizing linear state feedback con

  16. Further results on saturated globally stabilizing linear state feedback control laws for single-input neutrally stable planar systems

    NARCIS (Netherlands)

    Yang, Tao; Stoorvogel, Antonie Arij; Saberi, Ali; Johansson, Karl H.

    2013-01-01

    It is known that for single-input neutrally stable planar systems, there exists a class of saturated globally stabilizing linear state feedback control laws. The goal of this paper is to characterize the dynamic behavior for such a system under arbitrary locally stabilizing linear state feedback

  17. Controller design approach based on linear programming.

    Science.gov (United States)

    Tanaka, Ryo; Shibasaki, Hiroki; Ogawa, Hiromitsu; Murakami, Takahiro; Ishida, Yoshihisa

    2013-11-01

    This study explains and demonstrates the design method for a control system with a load disturbance observer. Observer gains are determined by linear programming (LP) in terms of the Routh-Hurwitz stability criterion and the final-value theorem. In addition, the control model has a feedback structure, and feedback gains are determined to be the linear quadratic regulator. The simulation results confirmed that compared with the conventional method, the output estimated by our proposed method converges to a reference input faster when a load disturbance is added to a control system. In addition, we also confirmed the effectiveness of the proposed method by performing an experiment with a DC motor.

  18. A Complete Parametric Solutions of Eigenstructure Assignment by State-Derivative Feedback for Linear Control Systems

    Directory of Open Access Journals (Sweden)

    T. H. S. Abdelaziz

    2005-01-01

    Full Text Available In this paper we introduce a complete parametric approach for solving the problem of eigenstructure assignment via state-derivative feedback for linear systems. This problem is always solvable for any controllable systems iff the open-loop system matrix is nonsingular. In this work, two parametric solutions to the feedback gain matrix are introduced that describe the available degrees of freedom offered by the state-derivative feedback in selecting the associated eigenvectors from an admissible class. These freedoms can be utilized to improve robustness of the closed-loop system. Accordingly, the sensitivity of the assigned eigenvalues to perturbations in the system and gain matrix is minimized. Numerical examples are included to show the effectiveness of the proposed approach. 

  19. Simulations of the TESLA Linear Collider with a Fast Feedback System

    CERN Document Server

    Schulte, Daniel; White, G

    2003-01-01

    The tolerances on the beams as they collide at the interaction point of the TESLA linear collider are very tight due to the nano-metre scale final vertical bunch spot sizes. Ground motion causes the beams to increase in emittance and drift out of collision leading to dramatic degradation of luminosity performance. To combat this, both slow orbit and fast intra-train feedback systems will be used. The design of these feedback systems depends critically on how component misalignment effects the beam throughout the whole accelerator. A simulation has been set up to study in detail the accelerator performance under such conditions by merging the codes of PLACET, MERLIN and GUINEA-PIG together with Simulink code to model feedback systems, all under a Matlab environment.

  20. Dynamical Sliding Mode Control of Ship Autopilot Based on Feedback Linearization%基于反馈线性化的船舶自动舵动态滑模控制

    Institute of Scientific and Technical Information of China (English)

    石为人; 邹剑; 宗志亚

    2011-01-01

    In order to reduce the autopilot operator's working strength and improve the safety and economic efficiency, this paper designs a dynamic sliding mode control according to the control of ship autopilot and combining high-order sliding mode control with dynamical sliding mode control. First, it establishes the nonlinear of ship control system with autopilot steering characteristics. Second, using the feedback linearization procedure of differential geometry, an equivalent, fully controllable and linear model is derived via a homomorphism transformation. At last, a dynamic sliding mode controller is designed. The results of simulation show that the dynamic sliding mode controller can not only automatically track the goals but also effectively reduce the system chattering problem, achieving the purpose and also offering a method for the research of autopilot control.%针对船舶自动舵的航向控制问题,结合高阶滑模和动态滑模控制的设计思想设计了一种船舶自动舵动态滑模控制器.首先设计出包含舵机特性的船舶航向控制仿射非线性系统模型,其次通过状态反馈的方法将原模型变为等价的完全可控型线性化系统,然后设计出动态滑模控制器.仿真结果表明,所设计的动态滑模控制器不仅能很好的自动跟踪设定的航向,而且能有效的抑制系统的抖振现象,达到设计目的,为研究船舶自动舵控制提供一种参考.

  1. Microcontroller-based Feedback Control Laboratory Experiments

    Directory of Open Access Journals (Sweden)

    Chiu Choi

    2014-06-01

    Full Text Available this paper is a result of the implementation of the recommendations on enhancing hands-on experience of control engineering education using single chip, small scale computers such as microcontrollers. A set of microcontroller-based feedback control experiments was developed for the Electrical Engineering curriculum at the University of North Florida. These experiments provided hands-on techniques that students can utilize in the development of complete solutions for a number of servo control problems. Significant effort was devoted to software development of feedback controllers and the associated signal conditioning circuits interfacing between the microcontroller and the physical plant. These experiments have stimulated the interest of our students in control engineering.

  2. Nonlinear Systems Feedback Linearization Optimal Zero-State-Error Control Under Disturbances Compensation

    Directory of Open Access Journals (Sweden)

    Gao Dexin

    2012-10-01

    Full Text Available This paper concentrates on the solution of state feedback exact linearization zero steady-state error optimal control problem for nonlinear systems affected by external disturbances. Firstly, the nonlinear system model with external disturbances is converted to quasi-linear system model by differential homeomorphism. Using Internal Model Optional Control (IMOC, the disturbances compensator is designed, which exactly offset the impact of external disturbances on the system. Taking the  system and the disturbances compensator in series, a new augmented system is obtained. Then the zero steady-state error optimal control problem is transformed into the optimal regulator design problem of an augmented system, and the optimal static error feedback control law is designed according to the different quadratic performance index. At last, the simulation results show the effectiveness of the method.

  3. Decentralized Output-Feedback Stabilization of Linear Time-invariant Interconnected Systems with Delays

    Energy Technology Data Exchange (ETDEWEB)

    Shim, D.S. [Chung-Ang University, Seoul (Korea, Republic of)

    1998-04-01

    We study the decentralized stabilization problem of linear time-invariant large-scale interconnected systems with delays without any system structure. We obtain sufficient stability conditions for interconnected systems which are equivalent to disturbance attenuation of some scaled system. A decentralized output-feedback controller is obtained using standard H{infinity} control theory. The obtained controller is delay-independent. We also obtain an observer for the interconnected system. (author). 9 refs.

  4. Distributed Cooperative Current-Sharing Control of Parallel Chargers Using Feedback Linearization

    OpenAIRE

    Jiangang Liu; Zhiwu Huang; Jing Wang; Jun Peng; Weirong Liu

    2014-01-01

    We propose a distributed current-sharing scheme to address the output current imbalance problem for the parallel chargers in the energy storage type light rail vehicle system. By treating the parallel chargers as a group of agents with output information sharing through communication network, the current-sharing control problem is recast as the consensus tracking problem of multiagents. To facilitate the design, input-output feedback linearization is first applied to transform the nonidentica...

  5. Feedforward and feedback optimal control for linear time-varying systems with persistent disturbances

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The optimal control problem was studied for linear time-varying systems, which was affected by external persistent disturbances with known dynamic characteristics but unknown initial conditions. To damp the effect of disturbances in an optimal fashion, we obtained a new feedforward and feedback optimal control law and gave the control algorithm by solving a Riccati differential equation and a matrix differential equation. Simulation results showed that the achieved optimal control law was realizable, efficient and robust to reject the external disturbances.

  6. Designing Linear Feedback Controller for Elastic Inverted Pendulum with Tip Mass

    Directory of Open Access Journals (Sweden)

    Minh Hoang Nguyen

    2016-12-01

    Full Text Available This paper introduced a kind of cart and pole system. The pole in this system is not a solid beam but an elastic beam. The paper analyzed the dynamic equation of this complex system. Then, a linear feedback controller was designed to stabilize this model in order to keep the elastic beam balanced in the up-side position. The control results were proved to work well through simulation.

  7. Feedforward and Feedback Optimal Control for Linear Systems with Sinusoidal Disturbances

    Institute of Scientific and Technical Information of China (English)

    唐功友

    2001-01-01

    The linear systems affected by additive external sinusoidal disturbances is studied. he problem is to damp this forced oscillation in an optimal fashion. The main result of this paper is a new design approach is proposed of realizable feedforward and feedback optimal control law for a linear timeinvariant system with sinusoidal disturbances. The algorithm of solving the optimal control law is given. It is shown that the control law is easily realized and is robust with respect to errors produced by the external sinusoidal disturbances through simulation results.

  8. Adaptive set-point tracking of the Lorenz chaotic system using non-linear feedback

    Energy Technology Data Exchange (ETDEWEB)

    Haghighatdar, F. [Department of Electronic Engineering, University of Isfahan, Hezar-Jerib St., Postal code: 8174673441, Isfahan (Iran, Islamic Republic of)], E-mail: fr_haghighat@yahoo.com; Ataei, M. [Department of Electronic Engineering, University of Isfahan, Hezar-Jerib St., Postal code: 8174673441, Isfahan (Iran, Islamic Republic of)], E-mail: mataei1971@yahoo.com

    2009-05-30

    In this paper, an adaptive control method for set-point tracking of the Lorenz chaotic system by using non-linear feedback is proposed. The design procedure of the proposed controller is accomplished in two steps. At the first step, using Lyapunov's direct method, a non-linear state feedback is selected so that without any need to apply identification techniques, in despite of the uncertain parameters existence in the system state equations, the asymptotic stability of the general Lorenz system is guaranteed in a stochastic point of the manifold containing general system equilibrium points. At the second step, a linear state feedback with adaptive gain is added to the prior controller to eliminate the tracking error. In order to guarantee the system asymptotic stability at desired set-point, the indirect Lyapunov's method is used. Finally, to show the effectiveness of the proposed methodology, the simulation results of different experiments including system parameters changes and set-point variation are provided.

  9. COA based robust output feedback UPFC controller design

    Energy Technology Data Exchange (ETDEWEB)

    Shayeghi, H., E-mail: hshayeghi@gmail.co [Technical Engineering Department, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of); Shayanfar, H.A. [Center of Excellence for Power System Automation and Operation, Electrical Engineering Department, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Jalilzadeh, S.; Safari, A. [Technical Engineering Department, Zanjan University, Zanjan (Iran, Islamic Republic of)

    2010-12-15

    In this paper, a novel method for the design of output feedback controller for unified power flow controller (UPFC) using chaotic optimization algorithm (COA) is developed. Chaotic optimization algorithms, which have the features of easy implementation, short execution time and robust mechanisms of escaping from the local optimum, is a promising tool for the engineering applications. The selection of the output feedback gains for the UPFC controllers is converted to an optimization problem with the time domain-based objective function which is solved by a COA based on Lozi map. Since chaotic mapping enjoys certainty, ergodicity and the stochastic property, the proposed chaotic optimization problem introduces chaos mapping using Lozi map chaotic sequences which increases its convergence rate and resulting precision. To ensure the robustness of the proposed stabilizers, the design process takes into account a wide range of operating conditions and system configurations. The effectiveness of the proposed controller for damping low frequency oscillations is tested and demonstrated through non-linear time-domain simulation and some performance indices studies. The results analysis reveals that the designed COA based output feedback UPFC damping controller has an excellent capability in damping power system low frequency oscillations and enhance greatly the dynamic stability of the power systems.

  10. Composite nonlinear feedback control for output regulation problem of linear discrete-time systems with input saturation

    Institute of Scientific and Technical Information of China (English)

    Chongwen Wang; Xing Chu; Weiyao Lan

    2014-01-01

    Transient performance for output regulation problems of linear discrete-time systems with input saturation is addressed by using the composite nonlinear feedback (CNF) control tech-nique. The regulator is designed to be an additive combination of a linear regulator part and a nonlinear feedback part. The linear regulator part solves the regulation problem independently which produces a quick output response but large oscil ations. The non-linear feedback part with wel-tuned parameters is introduced to improve the transient performance by smoothing the oscil atory convergence. It is shown that the introduction of the nonlinear feedback part does not change the solvability conditions of the linear discrete-time output regulation problem. The effectiveness of transient improvement is il ustrated by a numeric example.

  11. Linearizing Control of Induction Motor Based on Networked Control Systems

    Institute of Scientific and Technical Information of China (English)

    Jun Ren; Chun-Wen Li; De-Zong Zhao

    2009-01-01

    A new approach to speed control of induction motors is developed by introducing networked control systems (NCSs) into the induction motor driving system. The control strategy is to stabilize and track the rotor speed of the induction motor when the network time delay occurs in the transport medium of network data. First, a feedback linearization method is used to achieve input-output linearization and decoupling control of the induction motor driving system based on rotor flux model, and then the characteristic of network data is analyzed in terms of the inherent network time delay. A networked control model of an induction motor is established. The sufficient condition of asymptotic stability for the networked induction motor driving system is given, and the state feedback controller is obtained by solving the linear matrix inequalities (LMIs). Simulation results verify the efficiency of the proposed scheme.

  12. A recursive delayed output-feedback control to stabilize chaotic systems using linear-in-parameter neural networks

    Science.gov (United States)

    Yadmellat, Peyman; Nikravesh, S. Kamaleddin Yadavar

    2011-01-01

    In this paper, a recursive delayed output-feedback control strategy is considered for stabilizing unstable periodic orbit of unknown nonlinear chaotic systems. An unknown nonlinearity is directly estimated by a linear-in-parameter neural network which is then used in an observer structure. An on-line modified back propagation algorithm with e-modification is used to update the weights of the network. The globally uniformly ultimately boundedness of overall closed-loop system response is analytically ensured using Razumikhin lemma. To verify the effectiveness of the proposed observer-based controller, a set of simulations is performed on a Rossler system in comparison with several previous methods.

  13. Assessing the performance of data assimilation algorithms which employ linear error feedback.

    Science.gov (United States)

    Mallia-Parfitt, Noeleene; Bröcker, Jochen

    2016-10-01

    Data assimilation means to find an (approximate) trajectory of a dynamical model that (approximately) matches a given set of observations. A direct evaluation of the trajectory against the available observations is likely to yield a too optimistic view of performance, since the observations were already used to find the solution. A possible remedy is presented which simply consists of estimating that optimism, thereby giving a more realistic picture of the "out of sample" performance. Our approach is inspired by methods from statistical learning employed for model selection and assessment purposes in statistics. Applying similar ideas to data assimilation algorithms yields an operationally viable means of assessment. The approach can be used to improve the performance of models or the data assimilation itself. This is illustrated by optimising the feedback gain for data assimilation employing linear feedback.

  14. Linear stable unity-feedback system - Necessary and sufficient conditions for stability under nonlinear plant perturbations

    Science.gov (United States)

    Desoer, C. A.; Kabuli, M. G.

    1989-01-01

    The authors consider a linear (not necessarily time-invariant) stable unity-feedback system, where the plant and the compensator have normalized right-coprime factorizations. They study two cases of nonlinear plant perturbations (additive and feedback), with four subcases resulting from: (1) allowing exogenous input to Delta P or not; 2) allowing the observation of the output of Delta P or not. The plant perturbation Delta P is not required to be stable. Using the factorization approach, the authors obtain necessary and sufficient conditions for all cases in terms of two pairs of nonlinear pseudostate maps. Simple physical considerations explain the form of these necessary and sufficient conditions. Finally, the authors obtain the characterization of all perturbations Delta P for which the perturbed system remains stable.

  15. Time-delayed feedback control optimization for quasi linear systems under random excitations

    Institute of Scientific and Technical Information of China (English)

    Xueping Li; Detain Wei; Weiqiu Zhu

    2009-01-01

    A strategy for time-delayed feedback control optimization of quasi linear systems with random excita-tion is proposed. First, the stochastic averaging method is used to reduce the dimension of the state space and to derive the stationary response of the system. Secondly, the control law is assumed to be velocity feedback control with time delay and the unknown control gains are determined by the performance indices. The response of the controlled system is predicted through solving the Fokker-Plank-Kolmogorov equation associated with the averaged It6 equation. Finally, numerical examples are used to illustrate the proposed con-trol method, and the numerical results are confirmed by Monte Carlo simulation.

  16. State derivative feedback in second-order linear systems: A comparative analysis of perturbed eigenvalues under coefficient variation

    Science.gov (United States)

    Araújo, José M.; Dórea, Carlos E. T.; Gonçalves, Luiz M. G.; Datta, Biswa N.

    2016-08-01

    This paper presents a comparative study of sensitivity to parameter variation in two feedback techniques applied in second-order linear systems: state feedback technique and the less conventional state derivative feedback technique. The former uses information on displacements and velocities whereas the latter uses velocities and accelerations. Several contributions on the problem of partial or full eigenvalue/eigenstructure assignment using the state feedback technique are presented in the literature. Recently, some interesting possibilities, such as solving the regularization problem in singular mass second-order systems, are approached using state derivative feedback. In this work, a general equivalence between state feedback and state derivative feedback is first established. Then, figures of merit on the resulting perturbed spectrum are proposed in order to assess the sensitivity of the closed-loop system to variations on the system matrices. Numerical examples are presented to support the obtained results.

  17. Further results on the disturbance response of a double integrator controlled by a saturating linear static state feedback

    NARCIS (Netherlands)

    Wang, Xu; Saberi, Ali; Stoorvogel, Anton A.; Grip, H°avard Fjær

    2012-01-01

    In this paper, we study the response to external disturbances of a double integrator with a saturating feedback. For a class of disturbances that have bounded integrals over all intervals, we show that a linear static feedback law can always be designed to ensure boundedness of the states. Moreover,

  18. A new algorithm for pole assignment of single-input linear systems using state feedback

    Institute of Scientific and Technical Information of China (English)

    QIAN Jiang; CHENG Mingsong; XU Shufang

    2005-01-01

    In this paper we present a new algorithm for the single-input pole assignment problem using state feedback. This algorithm is based on the Schur decomposition of the closed-loop system matrix, and the numerically stable unitary transformations are used whenever possible, and hence it is numerically reliable.The good numerical behavior of this algorithm is also illustrated by numerical examples.

  19. Motion Control of underwater vehicle-manipulator systems using feedback linearization

    Directory of Open Access Journals (Sweden)

    Ingrid Schjølberg

    1996-01-01

    Full Text Available In this paper control of underwater vehicle-manipulator systems using feedback linearization has been studied. Performance, robustness and energy consumption of the system depend on the choice of output variables, these output variables can be chosen in several ways. In this paper two alternatives have been analysed by simulations, decoupling of the manipulator end-effector velocities from the vehicle velocities and from the total system momentum. The performance is almost the same for the two choices of decoupling schemes while robustness and energy consumption of the system depend on the accuracy of the dynamic model.

  20. Controlling chaos and synchronization for new chaotic system using linear feedback control

    Energy Technology Data Exchange (ETDEWEB)

    Yassen, M.T. [Mathematics Department, Faculty of Science, Mansoura University, Mansoura 35516 (Egypt)] e-mail: mtyassen@yahoo.com

    2005-11-01

    This paper is devoted to study the problem of controlling chaos for new chaotic dynamical system (four-scroll dynamical system). Linear feedback control is used to suppress chaos to unstable equilibria and to achieve chaos synchronization of two identical four-scroll systems. Routh-Hurwitz criteria is used to study the conditions of the asymptotic stability of the equilibrium points of the controlled system. The sufficient conditions for achieving synchronization of two identical four-scroll systems are derived by using Lyapunov stability theorem. Numerical simulations are presented to demonstrate the effectiveness of the proposed chaos control and synchronization schemes.

  1. Chaos control and global synchronization of Liu chaotic systems using linear balanced feedback control

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H.-H. [Department of Mechanical Engineering, HsiuPing Institute of Technology, Taichung 412, Taiwan (China)], E-mail: richard@mail.hit.edu.tw

    2009-04-15

    Liu chaotic systems exhibit two- or four-scroll attractors and are observed in a variety of engineering phenomena, including rigid body motion, brushless DC motor system and so forth. This study applies the Lyapunov stability theorem to identify the sufficient conditions for the asymptotic stability of the equilibrium points of Liu chaotic systems. A linear balanced feedback gain control method is then employed to design a controller to achieve the global synchronization of two identical four-scroll Liu chaotic systems. The feasibility and effectiveness of the proposed chaos stability and synchronization schemes are verified via numerical simulations.

  2. Adaptive neural control of non-affine pure-feedback non-linear systems with input nonlinearity and perturbed uncertainties

    Science.gov (United States)

    Zhang, Tian-Ping; Zhu, Qing; Yang, Yue-Quan

    2012-04-01

    In this article, two robust adaptive control schemes are investigated for a class of completely non-affine pure-feedback non-linear systems with input non-linearity and perturbed uncertainties using radial basis function neural networks (RBFNNs). Based on the dynamic surface control (DSC) technique and using the quadratic Lyapunov function, the explosion of complexity in the traditional backstepping design is avoided when the gain signs are known. In addition, the unknown virtual gain signs are dealt with using the Nussbaum functions. Using the mean value theorem and Young's inequality, only one learning parameter needs to be tuned online at each step of recursion. It is proved that the proposed design method is able to guarantee semi-global uniform ultimate boundedness (SGUUB) of all signals in the closed-loop system. Simulation results verify the effectiveness of the proposed approach.

  3. Relevance Feedback in Content Based Image Retrieval: A Review

    Directory of Open Access Journals (Sweden)

    Manesh B. Kokare

    2011-01-01

    Full Text Available This paper provides an overview of the technical achievements in the research area of relevance feedback (RF in content-based image retrieval (CBIR. Relevance feedback is a powerful technique in CBIR systems, in order to improve the performance of CBIR effectively. It is an open research area to the researcher to reduce the semantic gap between low-level features and high level concepts. The paper covers the current state of art of the research in relevance feedback in CBIR, various relevance feedback techniques and issues in relevance feedback are discussed in detail.

  4. Robust H_∞ static output feedback control of discrete-time switched polytopic linear systems with average dwell-time

    Institute of Scientific and Technical Information of China (English)

    QIU JianBin; FENG Gang; YANG Jie

    2009-01-01

    This paper investigates the problem of robust exponential H_∞ static output feedback controller design for a class of discrete-time switched linear systems with polytopic-type time-varying parametric uncertainties.The objective is to design a switched static output feedback controller guaranteeing the exponential stability of the resulting closed-loop system with a minimized exponential H_∞ performance under average dwell-time switching scheme.Based on a parameter-dependent discontinuous switched Lyapunov function combined with Finsler's lemma and Dualization lemma,some novel conditions for exponential H_∞ performance analysis are first proposed and in turn the static output feedback controller designs are developed.It is shown that the controller gains can be obtained by solving a set of linear matrix inequalities (LMIs),which are numerically efficient with commercially available software.Finally,a simulation example is provided to illustrate the effectiveness of the proposed approaches.

  5. The Effectiveness of Pre-Service English Teachers’ Collaborative Genre-Based Writing Feedback

    Directory of Open Access Journals (Sweden)

    Didik Rinan Sumekto

    2017-05-01

    Full Text Available This study investigated the collaborative genre-based effectiveness among the pre-service English teachers (PSETs. Data collection used the genre-based writing feedback observation upon its reflection and instruction and need analysis questionnaire. The data analysis used multivariate statistics method to generalize the writing tests. The findings showed that the PSETs’ feedback supported the interaction, accountability, and interdependence. These aspects were due to the collaborative participation in groups, in which the PSETs worked with the flexibility, entirely performed the quality, andcontributed in positive attitude during the meetings and assignments. The feedback emphasized the learning improvement within the formative reflection through the general linear model (GLM repeated measures analysis, where F=6,114 and p<0,01. This study concludes that the collaborative genre-based writing feedback has the positive response from the PSETs. The determinant ranges gains in between 85% to 90% after a series of genre-based writing lectures were conducted.

  6. Exploring the use of feedback in ERP-based BCI

    NARCIS (Netherlands)

    Schreuder, M.; Thurlings, M.E.; Brouwer, A.M.; Erp, J.B.F. van; Tangermann, M.

    2012-01-01

    Giving direct feedback on a mental state is common practice in motor imagery based brain-computer interfaces (BCI), but has not been reported for those based on eventrelated potentials (ERP). Potentially, such feedback could allow the user to adjust his strategy during a running trial to obtain the

  7. Relevance Feedback Algorithm Based on Collaborative Filtering in Image Retrieval

    Directory of Open Access Journals (Sweden)

    Yan Sun

    2010-12-01

    Full Text Available Content-based image retrieval is a very dynamic study field, and in this field, how to improve retrieval speed and retrieval accuracy is a hot issue. The retrieval performance can be improved when applying relevance feedback to image retrieval and introducing the participation of people to the retrieval process. However, as for many existing image retrieval methods, there are disadvantages of relevance feedback with information not being fully saved and used, and their accuracy and flexibility are relatively poor. Based on this, the collaborative filtering technology was combined with relevance feedback in this study, and an improved relevance feedback algorithm based on collaborative filtering was proposed. In the method, the collaborative filtering technology was used not only to predict the semantic relevance between images in database and the retrieval samples, but to analyze feedback log files in image retrieval, which can make the historical data of relevance feedback be fully used by image retrieval system, and further to improve the efficiency of feedback. The improved algorithm presented has been tested on the content-based image retrieval database, and the performance of the algorithm has been analyzed and compared with the existing algorithms. The experimental results showed that, compared with the traditional feedback algorithms, this method can obviously improve the efficiency of relevance feedback, and effectively promote the recall and precision of image retrieval.

  8. Decoupling Suspension Controller Based on Magnetic Flux Feedback

    Directory of Open Access Journals (Sweden)

    Wenqing Zhang

    2013-01-01

    Full Text Available The suspension module control system model has been established based on MIMO (multiple input and multiple output state feedback linearization. We have completed decoupling between double suspension points, and the new decoupling method has been applied to CMS04 magnetic suspension vehicle in national mid-low-speed maglev experiment field of Tangshan city in China. Double suspension system model is very accurate for investigating stability property of maglev control system. When magnetic flux signal is taken back to the suspension control system, the suspension module’s antijamming capacity for resisting suspension load variety has been proved. Also, the external force interference has been enhanced. As a result, the robustness and stability properties of double-electromagnet suspension control system have been enhanced.

  9. An accurate halo model for fitting non-linear cosmological power spectra and baryonic feedback models

    CERN Document Server

    Mead, Alexander; Heymans, Catherine; Joudaki, Shahab; Heavens, Alan

    2015-01-01

    We present an optimised variant of the halo model, designed to produce accurate matter power spectra well into the non-linear regime for a wide range of cosmological models. To do this, we introduce physically-motivated free parameters into the halo-model formalism and fit these to data from high-resolution N-body simulations. For a variety of $\\Lambda$CDM and $w$CDM models the halo-model power is accurate to $\\simeq 5$ per cent for $k\\leq 10h\\,\\mathrm{Mpc}^{-1}$ and $z\\leq 2$. We compare our results with recent revisions of the popular HALOFIT model and show that our predictions are more accurate. An advantage of our new halo model is that it can be adapted to account for the effects of baryonic feedback on the power spectrum. We demonstrate this by fitting the halo model to power spectra from the OWLS hydrodynamical simulation suite via parameters that govern halo internal structure. We are able to fit all feedback models investigated at the 5 per cent level using only two free parameters, and we place limi...

  10. Ultra-high-frequency piecewise-linear chaos using delayed feedback loops

    Science.gov (United States)

    Cohen, Seth D.; Rontani, Damien; Gauthier, Daniel J.

    2012-12-01

    We report on an ultra-high-frequency (>1 GHz), piecewise-linear chaotic system designed from low-cost, commercially available electronic components. The system is composed of two electronic time-delayed feedback loops: A primary analog loop with a variable gain that produces multi-mode oscillations centered around 2 GHz and a secondary loop that switches the variable gain between two different values by means of a digital-like signal. We demonstrate experimentally and numerically that such an approach allows for the simultaneous generation of analog and digital chaos, where the digital chaos can be used to partition the system's attractor, forming the foundation for a symbolic dynamics with potential applications in noise-resilient communications and radar.

  11. Application of Design Methodologies for Feedback Compensation Associated with Linear Systems

    Science.gov (United States)

    Smith, Monty J.

    1996-01-01

    The work that follows is concerned with the application of design methodologies for feedback compensation associated with linear systems. In general, the intent is to provide a well behaved closed loop system in terms of stability and robustness (internal signals remain bounded with a certain amount of uncertainty) and simultaneously achieve an acceptable level of performance. The approach here has been to convert the closed loop system and control synthesis problem into the interpolation setting. The interpolation formulation then serves as our mathematical representation of the design process. Lifting techniques have been used to solve the corresponding interpolation and control synthesis problems. Several applications using this multiobjective design methodology have been included to show the effectiveness of these techniques. In particular, the mixed H 2-H performance criteria with algorithm has been used on several examples including an F-18 HARV (High Angle of Attack Research Vehicle) for sensitivity performance.

  12. Stabilizability of linear quadratic state feedback for uncertain fuzzy time-delay systems.

    Science.gov (United States)

    Wang, Rong-Jyue; Lin, Wei-Wei; Wang, Wen-June

    2004-04-01

    This paper investigates the problem of designing a fuzzy state feedback controller to stabilize an uncertain fuzzy system with time-varying delay. Based on Lyapunov criterion and Razumikhin theorem, some sufficient conditions are derived under which the parallel-distributed fuzzy control can stabilize the whole uncertain fuzzy time-delay system asymptotically. By Schur complement, these sufficient conditions can be easily transformed into the problem of LMIs. Furthermore, the tolerable bound of the perturbation is also obtained. A practical example based on the continuous stirred tank reactor (CSTR) model is given to illustrate the control design and its effectiveness.

  13. Intricacies of Feedback in Computer-based Prism Adaptation Therapy

    DEFF Research Database (Denmark)

    Wilms, Inge Linda; Rytter, Hana Malá

    whether the PAT method can be executed with similar effect using a computer with a touch screen.   62 healthy subjects were subjected to two experimental conditions: 1) pointing out at targets using the original box, 2) pointing out at targets on a computer attached touch screen. In both conditions...... on the touch screen (indirect feedback), 2) the feedback was provided by seeing one's own pointing finger, with no graphical feedback on the computer screen (direct feedback).   The results show that it is possible to obtain similar aftereffects from PAT by using a computer method but only when providing...... a direct feedback (physical finger) on pointing precision. Attempts to provide feedback indirectly via icons on the computer screen fail to create the aftereffects observed in the original PAT. The findings have direct implications for future implementations of computer-based methods in treatment...

  14. Nonlinear SVM-DTC for induction motor drive using input-output feedback linearization and high order sliding mode control.

    Science.gov (United States)

    Ammar, Abdelkarim; Bourek, Amor; Benakcha, Abdelhamid

    2017-03-01

    This paper presents a nonlinear Direct Torque Control (DTC) strategy with Space Vector Modulation (SVM) for an induction motor. A nonlinear input-output feedback linearization (IOFL) is implemented to achieve a decoupled torque and flux control and the SVM is employed to reduce high torque and flux ripples. Furthermore, the control scheme performance is improved by inserting a super twisting speed controller in the outer loop and a load torque observer to enhance the speed regulation. The combining of dual nonlinear strategies ensures a good dynamic and robustness against parameters variation and disturbance. The system stability has been analyzed using Lyapunov stability theory. The effectiveness of the control algorithm is investigated by simulation and experimental validation using Matlab/Simulink software with real-time interface based on dSpace 1104.

  15. An Inquiry-Based Linear Algebra Class

    Science.gov (United States)

    Wang, Haohao; Posey, Lisa

    2011-01-01

    Linear algebra is a standard undergraduate mathematics course. This paper presents an overview of the design and implementation of an inquiry-based teaching material for the linear algebra course which emphasizes discovery learning, analytical thinking and individual creativity. The inquiry-based teaching material is designed to fit the needs of a…

  16. Bayesian integration and non-linear feedback control in a full-body motor task.

    Directory of Open Access Journals (Sweden)

    Ian H Stevenson

    2009-12-01

    Full Text Available A large number of experiments have asked to what degree human reaching movements can be understood as being close to optimal in a statistical sense. However, little is known about whether these principles are relevant for other classes of movements. Here we analyzed movement in a task that is similar to surfing or snowboarding. Human subjects stand on a force plate that measures their center of pressure. This center of pressure affects the acceleration of a cursor that is displayed in a noisy fashion (as a cloud of dots on a projection screen while the subject is incentivized to keep the cursor close to a fixed position. We find that salient aspects of observed behavior are well-described by optimal control models where a Bayesian estimation model (Kalman filter is combined with an optimal controller (either a Linear-Quadratic-Regulator or Bang-bang controller. We find evidence that subjects integrate information over time taking into account uncertainty. However, behavior in this continuous steering task appears to be a highly non-linear function of the visual feedback. While the nervous system appears to implement Bayes-like mechanisms for a full-body, dynamic task, it may additionally take into account the specific costs and constraints of the task.

  17. Design and Evaluation of Accelerometer based Motional Feedback

    DEFF Research Database (Denmark)

    Schneider, Henrik; Pranjic, Emilio; Agerkvist, Finn T.;

    2015-01-01

    The electro dynamic loudspeaker is often referred to as the weakest link in the audio chain due to low efficiency and high distortion levels at low frequencies and high diaphragm excursion. Compensating for loudspeaker non-linearities using feedback or feedforward methods can improve the distorti...

  18. 基于反馈线性化技术的直驱永磁同步风电机组低电压穿越研究%A low voltage ride through scheme of PMSG wind power systems based on feedback linearization technology

    Institute of Scientific and Technical Information of China (English)

    魏杰; 邱晓燕; 陈光堂; 崔伟; 张冰冰; 庄哲; 郑乔

    2013-01-01

    This paper proposes aAfter analyzing the wind turbine with a direct-driven PMSG, a low voltage ride through scheme of PMSG wind power systems based on feedback linearization through anis proposedalyzing the wind turbine with a direct-driven PMSG. The DC-Linklink voltage is maintained and regulated by generator-side converter. Considering the nonlinear relationship between the DC -Linklink voltage and the generator rotor speed, the controller of DC -Linklink voltage uses a feedback linearization technology. The grid-side converter which controls the grid-side active power according to the maximum power point tracking adds a judgment link for the generator speed reference.. The model of 2 MW PMSG wind power system was simulated by using PSCAD. The simulation results has have verified the validity of the proposed control scheme.%通过对直驱永磁同步风电系统的研究,提出了一种基于反馈线性化的低电压穿越控制策略.直流母线电压由发电机侧整流器来维持调节,考虑到直流母线电压和发电机转子转速的非线性关系,直流母线电压的控制采用了反馈线性化技术.网侧逆变器根据最大风能跟踪原则来控制网侧有功功率,并加入了转子速度参考值的判定环节.运用PSCAD仿真平台建立了一个2 MW的直驱永磁同步风电系统,验证了其正确性和有效性.

  19. Linear permeability evolution of expanding conduits due to feedback between flow and fast phase change

    Science.gov (United States)

    Wang, Lichun; Cardenas, M. Bayani

    2017-05-01

    Conduits are ubiquitous and critical pathways for many fluids relevant for geophysical processes such as magma, water, and gases. Predicting flow through conduits is challenging when the conduit geometry coevolves with the flow. We theoretically show that the permeability (k) of a conduit whose walls are eroding due to fast phase change increases linearly with time because of a self-reinforcing mechanism. This simple result is surprising given complex feedbacks between flow, transport, and phase change. The theory is congruent with previous experimental observations of fracture dissolution in calcite. Supporting computational fracture dissolution experiments showed that k only slightly increases until the dissolution front reaches the narrowest conduit constriction, after which the linear evolution of k manifests. The theory holds across multiple scales and a broad range of Peclet and Damkohler numbers and thus advances the prediction of dynamic mass fluxes through expanding conduits in various geologic and environmental settings.Plain Language SummaryGeological conduits are ubiquitous present in the subsurface. In many situations, these conduits may enlarge through time due to erosion of its walls by dissolution and melting. This leads to strongly coupled flow and reactive transport processes where the flow dictates the wall's erosion and vice versa. As the conduit expands, so does its permeability and thus flow. Thus, predicting fluid flow and relevant transport processes through expanding conduits is challenging. In this study, we presented a theory for the linear time dependence of permeability for expanding conduits. The theory is congruent with previous observations from fracture dissolution in calcite. An additional series of our own computational experiments also aligns with the theory. The theory will be of interest to geoscientists and engineers in many fields such as hydrology, glaciology, and petroleum engineering, to name a few.

  20. Fractal Erosion of the Safe Basin in a Helmholtz Oscillator and Its Control by Linear Delayed Velocity Feedback

    Institute of Scientific and Technical Information of China (English)

    SHANG Hui-Lin; WEN Yong-Peng

    2011-01-01

    Fractal erosion of the safe basin in a Helmholtz oscillator system is studied. A linear delayed velocity feedback is employed to suppress the fractal erosion. The necessary basin erosion condition of the delayed feedback controlled system is obtained. The evolution of the boundary and area of the safe basin over time delay is also presented. It follows that the delayed velocity feedback can be used as an effective strategy to control fractal erosion of a safe basin.%Fractal erosion of the safe basin in a Helmholtz oscillator system is studied.A linear delayed velocity feedback is employed to suppress the fractal erosion.The necessary basin erosion condition of the delayed feedback controlled system is obtained.The evolution of the boundary and area of the safe basin over time delay is also presented.It follows that the delayed velocity feedback can be used as an effective strategy to control fractal erosion of a safe basin.Since the safe basin was induced to explain the integrity of dynamical systems,studies on safe basins have attracted much attention.[1-6] Leigh and Armin calculated the survival probability of a ferry in random seas by estimating the erosion of the safe basin during the ship rolling motion by using Monte Carlo simulations.[1] Lenci and Rega induced the erosion of a safe basin to explain pull-in phenomenon in micro-electro mechanical systems.[2

  1. Stability and control synthesis for discrete-time linear systems subject to actuator saturation by output feedback

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available This paper presents sufficient conditions of asymptotic stability for discrete-time linear systems subject to actuator saturations with an output feedback law. The derived stability results are given in terms of LMIs. A new proof is presented to obtain previous conditions of asymptotic stability. A numerical example is used to illustrate this technique by using a linear optimization problem subject to LMI constraints.

  2. Frequency-domain criterion for the chaos synchronization of time-delay power systems under linear feedback control

    Indian Academy of Sciences (India)

    Qian Lin; Xiaofeng Wu; Yun Chen

    2015-12-01

    This paper studies the global synchronization of non-autonomous, time-delay, chaotic power systems via linear state-error feedback control. The frequency domain criterion and the LMI criterion are proposed and applied to design the coupling matrix. Some algebraic criteria via a single-variable linear coupling are derived and formulated in simple algebraic inequalities. The effectiveness of the new criteria is illustrated with numerical examples.

  3. Linear feature detection based on ridgelet

    Institute of Scientific and Technical Information of China (English)

    HOU; Biao; (侯彪); LIU; Fang; (刘芳); JIAO; Licheng; (焦李成)

    2003-01-01

    Linear feature detection is very important in image processing. The detection efficiency will directly affect the perfomance of pattern recognition and pattern classification. Based on the idea of ridgelet, this paper presents a new discrete localized ridgelet transform and a new method for detecting linear feature in anisotropic images. Experimental results prove the efficiency of the proposed method.

  4. Feedback Blunting: Total Sleep Deprivation Impairs Decision Making that Requires Updating Based on Feedback.

    Science.gov (United States)

    Whitney, Paul; Hinson, John M; Jackson, Melinda L; Van Dongen, Hans P A

    2015-05-01

    To better understand the sometimes catastrophic effects of sleep loss on naturalistic decision making, we investigated effects of sleep deprivation on decision making in a reversal learning paradigm requiring acquisition and updating of information based on outcome feedback. Subjects were randomized to a sleep deprivation or control condition, with performance testing at baseline, after 2 nights of total sleep deprivation (or rested control), and following 2 nights of recovery sleep. Subjects performed a decision task involving initial learning of go and no go response sets followed by unannounced reversal of contingencies, requiring use of outcome feedback for decisions. A working memory scanning task and psychomotor vigilance test were also administered. Six consecutive days and nights in a controlled laboratory environment with continuous behavioral monitoring. Twenty-six subjects (22-40 y of age; 10 women). Thirteen subjects were randomized to a 62-h total sleep deprivation condition; the others were controls. Unlike controls, sleep deprived subjects had difficulty with initial learning of go and no go stimuli sets and had profound impairment adapting to reversal. Skin conductance responses to outcome feedback were diminished, indicating blunted affective reactions to feedback accompanying sleep deprivation. Working memory scanning performance was not significantly affected by sleep deprivation. And although sleep deprived subjects showed expected attentional lapses, these could not account for impairments in reversal learning decision making. Sleep deprivation is particularly problematic for decision making involving uncertainty and unexpected change. Blunted reactions to feedback while sleep deprived underlie failures to adapt to uncertainty and changing contingencies. Thus, an error may register, but with diminished effect because of reduced affective valence of the feedback or because the feedback is not cognitively bound with the choice. This has important

  5. Medicare FFS Physician Feedback Program Value-Based Payment

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Physician Feedback - Value-Based Modifier Program provides comparative performance information to physicians as one part of Medicares efforts to improve the...

  6. Towards App-based Formative Feedback to Support Summarizing Skills

    NARCIS (Netherlands)

    Van Rosmalen, Peter; Kester, Liesbeth; Boshuizen, Els

    2013-01-01

    Van Rosmalen, P., Kester, L., & Boshuizen, H. P. A. (2013, 18 September). Towards App‐based Formative Feedback to Support Summarizing Skills. Presentation given at ECTEL 2013: Workshop on Technology-Enhanced Formative Assessment (TEFA), Paphos, Cyprus.

  7. Interface Prostheses with Classifier-Feedback based User Training.

    Science.gov (United States)

    Fang, Yinfeng; Zhou, Dalin; Li, Kairu; Liu, Honghai

    2016-12-21

    It is evident that user training significantly affects performance of pattern-recognition based myoelectric prosthetic device control. Despite plausible classification accuracy on offline datasets, online accuracy usually suffers from the changes in physiological conditions and electrode displacement. The user ability in generating consistent EMG patterns can be enhanced via proper user training strategies in order to improve online performance. This study proposes a clustering-feedback strategy that provides real-time feedback to users by means of a visualised online EMG signal input as well as the centroids of the training samples, whose dimensionality is reduced to minimal number by dimension reduction. Clustering-feedback provides a criterion that guides users to adjust motion gestures and muscle contraction forces intentionally. The experiment results have demonstrated that hand motion recognition accuracy increases steadily along the progress of the clustering-feedback based user training, while conventional classifier-feedback methods, i.e. label-feedback, hardly achieve any improvement. The result concludes that the use of proper classifier-feedback can accelerate the process of user training, and implies prosperous future for the amputees with limited or no experience in pattern-recognition based prosthetic device manipulation.

  8. Distributed Cooperative Current-Sharing Control of Parallel Chargers Using Feedback Linearization

    Directory of Open Access Journals (Sweden)

    Jiangang Liu

    2014-01-01

    Full Text Available We propose a distributed current-sharing scheme to address the output current imbalance problem for the parallel chargers in the energy storage type light rail vehicle system. By treating the parallel chargers as a group of agents with output information sharing through communication network, the current-sharing control problem is recast as the consensus tracking problem of multiagents. To facilitate the design, input-output feedback linearization is first applied to transform the nonidentical nonlinear charging system model into the first-order integrator. Then, a general saturation function is introduced to design the cooperative current-sharing control law which can guarantee the boundedness of the proposed control. The cooperative stability of the closed-loop system under fixed and dynamic communication topologies is rigorously proved with the aid of Lyapunov function and LaSalle invariant principle. Simulation using a multicharging test system further illustrates that the output currents of parallel chargers are balanced using the proposed control.

  9. Partial Feedback Linearization on a Harmonically Excited Beam with One-Sided Spring

    Science.gov (United States)

    HEERTJES, M. F.; VAN DE MOLENGRAFT, M. J. G.; NIJMEIJER, H.

    1999-12-01

    Partial feedback linearization is applied to a harmonically excited beam with one-sided spring to reduce vibration amplitudes while keeping the control effort small. Vibration amplitudes are reduced by globally stabilizing the small amplitude 1-periodic solution which is one of the coexisting solutions. As the 1-periodic solution represents a natural solution of the uncontrolled system, no control effort will be needed once the system vibrates in the 1-periodic response. To control the multi-degree-of-freedom (d.o.f.) beam system to the 1-periodic solution, only one actuator is used that controls one (d.o.f.). The behaviour of the other d.o.f.s is eventually described by the zero dynamics. Whether these d.o.f.s converge to the 1-periodic solution depends on the stability of the zero dynamics. The global asymptotic stability of the non-autonomous zero dynamics can be partially determined by a frequency domain technique known as the circle criterion. However, the circle criterion does not guarantee stability at all actuator positions along the beam

  10. Procedure for preventing response strain on random interval schedules with a linear feedback loop.

    Science.gov (United States)

    Reed, Phil

    2016-03-01

    An experiment examined the impact of a procedure designed to prevent response or extinction strain occurring on random interval schedules with a linear feedback loop (i.e., an RI+ schedule). Rats lever-pressed for food reinforcement on either a RI+ or a random interval (RI) schedule that was matched to the RI+ schedule in terms of reinforcement rate. Two groups of rats responded on an RI+ and two on an RI schedule matched for rate of reinforcement. One group on each schedule also received response-independent food if there had been no response for 60 s, and response-independent food continued to be delivered on an RT-60 schedule until a response was made. Rats on the RI and RI+ obtained similar rates of reinforcement and had similar reinforced inter-response times to one another. On the schedules without response-independent food, rats had similar rates of response to one another. However, while the delivery of response-independent food reduced rates of response on an RI schedule, they enhanced response rates on an RI+ schedule. These results suggest that rats can display sensitivity to the molar aspects of the free-operant contingency, when procedures are implemented to reduce the impact of factors such as extinction-strain.

  11. Integrated nozzle - flapper valve with piezoelectric actuator and isothermal chamber: a feedback linearization multi control device

    Energy Technology Data Exchange (ETDEWEB)

    Kamali, Mohammadreza; Jazayeri, Seyed Ali [K. N.Toosi University of Technology, Tehran (Iran, Islamic Republic of); Najafi, Farid [University of Guilan, Rasht (Iran, Islamic Republic of); Kawashima, Kenji [Tokyo Medical and Dental University, Tokyo (Japan); Kagawa, Toshiharu [Tokyo Institute of Technology, Tokyo (Japan)

    2016-05-15

    This paper introduces a new nozzle-flapper valve with isothermal chamber using piezoelectric actuator. It controls the pressure and flow rate simply, effectively and separately. The proposed valve uses isothermal chamber presenting practical isothermal condition due to its large heat transfer interfaces filled by metal wool. The valve uses stacked type piezoelectric actuator with unique advantages. By using this valve, a simple method has been fulfilled to control flow rate or pressure of ideal gases in a pneumatic actuators. Experimental results demonstrated applications of the proposed valve to control either pressure or flow rate in pneumatic circuits. This valve can be also used in the pilot stage valve to actuate the main stage of a much bigger pneumatic valve. Designated structure contains only one pressure sensor installed on the isothermal control chamber, capable of controlling both pressure and flow rate. The desired output mass flow rate of the valve is controlled by the pressure changes during positioning of piezoelectric actuator at proper position. The proposed valve can control steady and unsteady oscillatory flow rate and pressure effectively, using nonlinear control method such as feedback linearization approach. Its effectiveness is demonstrated and validated through simulation and experiments.

  12. Visual Feedback for Rover-based Coring

    Science.gov (United States)

    Backes, Paul; Helmick, Daniel; Bajracharya, Max

    2008-01-01

    Technology for coring from a low-mass rover has been developed to enable core sample acquisition where a planetary rover experiences moderate slip during the coring operation. A new stereo vision technique, Absolute Motion Visual Odometry, is used to measure rover slip during coring and the slip is accommodated through corresponding arm pose updating. Coring rate is controlled by feedback of themeasured force of the coring tool against the environment. Test results in the JPL Marsyard show for the first time that coring from a low-mass rover with slip is feasible.

  13. A Feedback-Based Web Search Engine

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei-feng; XU Bao-wen; ZHOU Xiao-yu

    2004-01-01

    Web search engines are very useful information service tools in the Internet.The current web search engines produce search results relating to the search terms and the actual information collected by them.Since the selections of the search results cannot affect the future ones, they may not cover most people's interests.In this paper, feedback information produced by the users' accessing lists will be represented by the rough set and can reconstruct the query string and influence the search results.And thus the search engines can provide self-adaptability.

  14. Nonlinear signal-based control with an error feedback action for nonlinear substructuring control

    Science.gov (United States)

    Enokida, Ryuta; Kajiwara, Koichi

    2017-01-01

    A nonlinear signal-based control (NSBC) method utilises the 'nonlinear signal' that is obtained from the outputs of a controlled system and its linear model under the same input signal. Although this method has been examined in numerical simulations of nonlinear systems, its application in physical experiments has not been studied. In this paper, we study an application of NSBC in physical experiments and incorporate an error feedback action into the method to minimise the error and enhance the feasibility in practice. Focusing on NSBC in substructure testing methods, we propose nonlinear substructuring control (NLSC), that is a more general form of linear substructuring control (LSC) developed for dynamical substructured systems. In this study, we experimentally and numerically verified the proposed NLSC via substructuring tests on a rubber bearing used in base-isolated structures. In the examinations, NLSC succeeded in gaining accurate results despite significant nonlinear hysteresis and unknown parameters in the substructures. The nonlinear signal feedback action in NLSC was found to be notably effective in minimising the error caused by nonlinearity or unknown properties in the controlled system. In addition, the error feedback action in NLSC was found to be essential for maintaining stability. A stability analysis based on the Nyquist criterion, which is used particularly for linear systems, was also found to be efficient for predicting the instability conditions of substructuring tests with NLSC and useful for the error feedback controller design.

  15. A Bayesian matching pursuit based scheduling algorithm for feedback reduction in MIMO broadcast channels

    KAUST Repository

    Shibli, Hussain J.

    2013-06-01

    Opportunistic schedulers rely on the feedback of all users in order to schedule a set of users with favorable channel conditions. While the downlink channels can be easily estimated at all user terminals via a single broadcast, several key challenges are faced during uplink transmission. First of all, the statistics of the noisy and fading feedback channels are unknown at the base station (BS) and channel training is usually required from all users. Secondly, the amount of network resources (air-time) required for feedback transmission grows linearly with the number of users. In this paper, we tackle the above challenges and propose a Bayesian based scheduling algorithm that 1) reduces the air-time required to identify the strong users, and 2) is agnostic to the statistics of the feedback channels and utilizes the a priori statistics of the additive noise to identify the strong users. Numerical results show that the proposed algorithm reduces the feedback air-time while improving detection in the presence of fading and noisy channels when compared to recent compressed sensing based algorithms. Furthermore, the proposed algorithm achieves a sum-rate throughput close to that obtained by noiseless dedicated feedback systems. © 2013 IEEE.

  16. 基于微分几何反馈线性化的PMSM混合H2/H∞控制%Mixed H2/H∞ Control of PMSM Based on Differential Geometry Feedback Linearization

    Institute of Scientific and Technical Information of China (English)

    严大虎; 纪志成

    2011-01-01

    Aimed to the speed control problem of permanent magnet synchronous servo system, firstly, nonlinear model of permanent magnet synchronous servo system was converted into linear model whose suitable performance index function of the was selected, using differential geometric method. And then the external disturbance existing in system operation was effectively suppressed while the system stability was maintained by using of the mixed H2/H, control method. Simulation results illustrate that the system design method has many advantages such as high speed in response, good dynamic performance and steady state performance,and has strong robustness to external disturbances such as load. The engineering realization of this method is easily reached because of simple control parameters.%针对永磁同步伺服系统中的速度控制问题,首先运用微分几何方法将永磁同步电动机的非线性数学模型转化成了线性模型,并针对该线性模型选择合适的性能指标函数,采用混合H2/H∞控制方法在保证系统稳定的同时有效地抑制了系统运行中存在的外部扰动.仿真结果表明:该系统设计方案具有速度响应快,稳、动态性能好,并且对负载等外部扰动鲁棒性强的特点,控制参数简单,易于工程实现.

  17. Sufficient LMI conditions and Lyapunov redesign for the robust stability of a class of feedback linearized dynamical systems.

    Science.gov (United States)

    Azizi, Sajad

    2017-05-01

    The robust stability of a class of feedback linearizable minimum-phase nonlinear system, having parametric uncertainties, is investigated in this study. The system in new coordinates is represented to an equivalent formulation after the attempt of feedback linearization. Due to the parametric uncertainties the approximately linearized system entails a norm bounded input nonlinearity such that the equilibrium point condition in error dynamics can not be satisfied. Accordingly, to guarantee the regional asymptotic stability a control synthesis problem is proposed by means of sufficient Linear Matrix Inequalities (LMIs) together with an amended nonlinear control term, derived from the Lyapunov redesign method, which tackles zero steady-state error condition. The numerical examples of a general aviation aircraft's longitudinal dynamics and inverted pendulum are simulated to show the proficiency of the proposed control technique. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  18. Feedback-Based Collaborative Secrecy Encoding over Binary Symmetric Channels

    CERN Document Server

    Amariucai, George

    2009-01-01

    In this paper we propose a feedback scheme for transmitting secret messages between two legitimate parties, over an eavesdropped communication link. Relative to Wyner's traditional encoding scheme \\cite{wyner1}, our feedback-based encoding often yields larger rate-equivocation regions and achievable secrecy rates. More importantly, by exploiting the channel randomness inherent in the feedback channels, our scheme achieves a strictly positive secrecy rate even when the eavesdropper's channel is less noisy than the legitimate receiver's channel. All channels are modeled as binary and symmetric (BSC). We demonstrate the versatility of our feedback-based encoding method by using it in three different configurations: the stand-alone configuration, the mixed configuration (when it combines with Wyner's scheme \\cite{wyner1}), and the reversed configuration. Depending on the channel conditions, significant improvements over Wyner's secrecy capacity can be observed in all configurations.

  19. Haptic Feedback for the GPU-based Surgical Simulator

    DEFF Research Database (Denmark)

    Sørensen, Thomas Sangild; Mosegaard, Jesper

    2006-01-01

    The GPU has proven to be a powerful processor to compute spring-mass based surgical simulations. It has not previously been shown however, how to effectively implement haptic interaction with a simulation running entirely on the GPU. This paper describes a method to calculate haptic feedback...... with limited performance cost. It allows easy balancing of the GPU workload between calculations of simulation, visualisation, and the haptic feedback....

  20. Stabilization of a class of discrete-time switched systems via observer-based output feedback

    Institute of Scientific and Technical Information of China (English)

    Jiao LI; Yuzhong LIU

    2007-01-01

    In this paper, observer-based static output feedback control problem for discrete-time uncertain switched systems is investigated under an arbitrary switching rule. The main method used in this note is combining switched. Lyapunov function (SLF) method with Finsler's Lemma. Based on linear matrix inequality (LMI) a less conservative stability condition is established and this condition allows extra degree of freedom for stability analysis. Finally, a simulation example is given to illustrate the efficiency of the result.

  1. Conversion of linear time-invariant time-delay feedback systems into delay-differential equations with commensurate delays

    Science.gov (United States)

    Yamazaki, Tatsuya; Hagiwara, Tomomichi

    2014-08-01

    A new stability analysis method of time-delay systems (TDSs) called the monodromy operator approach has been studied under the assumption that a TDS is represented as a time-delay feedback system consisting of a finite-dimensional linear time-invariant (LTI) system and a pure delay. For applying this approach to TDSs described by delay-differential equations (DDEs), the problem of converting DDEs into representation as time-delay feedback systems has been studied. With regard to such a problem, it was shown that, under discontinuous initial functions, it is natural to define the solutions of DDEs in two different ways, and the above conversion problem was solved for each of these two definitions. More precisely, the solution of a DDE was represented as either the state of the finite-dimensional part of a time-delay feedback system or a part of the output of another time-delay feedback system, depending on which definition of the DDE solution one is talking about. Motivated by the importance in establishing a thorough relationship between time-delay feedback systems and DDEs, this paper discusses the opposite problem of converting time-delay feedback systems into representation as DDEs, including the discussions about the conversion of the initial conditions. We show that the state of (the finite-dimensional part of) a time-delay feedback system can be represented as the solution of a DDE in the sense of one of the two definitions, while its 'essential' output can be represented as that of another DDE in the sense of the other type of definition. Rigorously speaking, however, it is also shown that the latter representation is possible regardless of the initial conditions, while some initial condition could prevent the conversion into the former representation. This study hence establishes that the representation of TDSs as time-delay feedback systems possesses higher ability than that with DDEs, as description methods for LTI TDSs with commensurate delays.

  2. Development of Linearizing Feedback Control with a Variable Structure Observer for Continuous Stirred Tank Reactors

    Institute of Scientific and Technical Information of China (English)

    Bachir Daaou; Abdellah Mansouri; Mohamed Bouhamida; Mohammed Chenafa

    2012-01-01

    This paper deals with the design of an observer-based nonlinear control for continuous stirred tank reactors (CSTR). A variable structure observer is constructed to estimate the whole process state variables. This observer is basically the conventional Luenberger observer with an additional switching term used to guarantee the robustness against modeling errors. The observer is coupled with a nonlinear controller, designed based on input-output linearization for controlling the reactor temperature. The asymptotical stability of the closed-loop system is shown by the Lyapunov stability theorem. Finally, computer simulations are developed for showing the performance of the proposed approach.

  3. A modular positive feedback-based gene amplifier

    Directory of Open Access Journals (Sweden)

    Bhalerao Kaustubh D

    2010-02-01

    Full Text Available Abstract Background Positive feedback is a common mechanism used in the regulation of many gene circuits as it can amplify the response to inducers and also generate binary outputs and hysteresis. In the context of electrical circuit design, positive feedback is often considered in the design of amplifiers. Similar approaches, therefore, may be used for the design of amplifiers in synthetic gene circuits with applications, for example, in cell-based sensors. Results We developed a modular positive feedback circuit that can function as a genetic signal amplifier, heightening the sensitivity to inducer signals as well as increasing maximum expression levels without the need for an external cofactor. The design utilizes a constitutively active, autoinducer-independent variant of the quorum-sensing regulator LuxR. We experimentally tested the ability of the positive feedback module to separately amplify the output of a one-component tetracycline sensor and a two-component aspartate sensor. In each case, the positive feedback module amplified the response to the respective inducers, both with regards to the dynamic range and sensitivity. Conclusions The advantage of our design is that the actual feedback mechanism depends only on a single gene and does not require any other modulation. Furthermore, this circuit can amplify any transcriptional signal, not just one encoded within the circuit or tuned by an external inducer. As our design is modular, it can potentially be used as a component in the design of more complex synthetic gene circuits.

  4. Comparison of linear and nonlinear feedback control of heart rate for treadmill running

    National Research Council Canada - National Science Library

    Hunt, Kenneth J; Maurer, Roman R

    2016-01-01

    Heart rate can be used to define exercise intensity; feedback control systems for treadmills which automatically adjust speed to track arbitrary heart rate target profiles are therefore of interest...

  5. Combining Convex-Concave Decompositions and Linearization Approaches for solving BMIs, with application to Static Output Feedback

    CERN Document Server

    Dinh, Quoc Tran; Michiels, Wim; Diehl, Moritz

    2011-01-01

    A novel optimization method is proposed to minimize a convex function subject to bilinear matrix inequality (BMI) constraints. The key idea is to decompose the bilinear mapping as a difference between two positive semidefinite convex mappings. At each iteration of the algorithm the concave part is linearized, leading to a convex subproblem.Applications to various output feedback controller synthesis problems are presented. In these applications the subproblem in each iteration step can be turned into a convex optimization problem with linear matrix inequality (LMI) constraints. The performance of the algorithm has been benchmarked on the data from COMPleib library.

  6. Spintronic Oscillator based on feed-back mechanism

    Science.gov (United States)

    Tulapurkar, Ashwin; Dixit, Dinesh; Konishi, Katsunori; Tomy, C.; Suzuki, Yoshishige

    2012-02-01

    Nano-scale rf oscillators based on the magnetic tunnel junctions is an active area of research. These oscillators are based on the spin-transfer torque effect, in which a dc current drives the magnetization into precessional motion. Here we present a novel design of a spintronic oscillator which is not based on spin-transfer torque effect. This new oscillator is comprised of a magnetic tunnel junction whose top and bottom contacts are connected to a bias-T. A dc current is passed through the low frequency port of the bias-T and the high frequency port is connected to a ``feed-back'' wire which runs below the MTJ. Any fluctuation in the magnetization direction of the free layer of MTJ, drives ac current through the feed-back wire, which in turn exerts ac magnetic field on the free layer. The feedback wire is oriented such that the ac magnetic field amplifies the magnetization fluctuations for positive value of dc current. For negative value of dc current, the feedback loop suppresses the fluctuations. We find that if the positive dc current passing through the MTJ is more than a critical value, continuous precessing states of the magnetization are possible. Oscillators with better quality factors are possible using the feedback scheme.

  7. The effects of different quantum feedback types on the tightness of the variance-based uncertainty

    Science.gov (United States)

    Zheng, Xiao; Zhang, Guo-Feng

    2017-03-01

    The effect of the quantum feedback on the tightness of the variance-based uncertainty, the possibility of using quantum feedback to prepare the state with a better tightness, and the relationship between the tightness of the uncertainty and the mixedness of the system are studied. It is found that the tightness of Schrodinger-Robertson uncertainty (SUR) relation has a strict liner relationship with the mixedness of the system. As for the Robertson uncertainty relation (RUR), we find that the tightness can be enhanced by tuning the feedback at the beginning of the evolution. In addition, we deduce that the tightness of RUR has an inverse relationship with the mixedness and the relationship turns into a strict linear one when the system reach the steady state.

  8. A Contrastive Analysis on Web-based Intercultural Peer Feedback

    Directory of Open Access Journals (Sweden)

    Qin Wang

    2013-11-01

    Full Text Available This paper made a contrastive analysis on peer feedback generated by Chinese EFL learners and Native Speakers of English, who participated in a web-based Cross-Pacific Writing Exchange program. The analysis mainly focused on differences in terms of commenting size, nature and function; the pragmatic differences between two groups of learners were investigated as well. The present study afforded us lessons for peer review training program and provided pedagogical implications for L2 writing. Keywords: peer feedback; web-based; intercultural; contrastive analysis

  9. Linear Regression Based Real-Time Filtering

    Directory of Open Access Journals (Sweden)

    Misel Batmend

    2013-01-01

    Full Text Available This paper introduces real time filtering method based on linear least squares fitted line. Method can be used in case that a filtered signal is linear. This constraint narrows a band of potential applications. Advantage over Kalman filter is that it is computationally less expensive. The paper further deals with application of introduced method on filtering data used to evaluate a position of engraved material with respect to engraving machine. The filter was implemented to the CNC engraving machine control system. Experiments showing its performance are included.

  10. Quaternion-based adaptive output feedback attitude control of spacecraft using Chebyshev neural networks.

    Science.gov (United States)

    Zou, An-Min; Dev Kumar, Krishna; Hou, Zeng-Guang

    2010-09-01

    This paper investigates the problem of output feedback attitude control of an uncertain spacecraft. Two robust adaptive output feedback controllers based on Chebyshev neural networks (CNN) termed adaptive neural networks (NN) controller-I and adaptive NN controller-II are proposed for the attitude tracking control of spacecraft. The four-parameter representations (quaternion) are employed to describe the spacecraft attitude for global representation without singularities. The nonlinear reduced-order observer is used to estimate the derivative of the spacecraft output, and the CNN is introduced to further improve the control performance through approximating the spacecraft attitude motion. The implementation of the basis functions of the CNN used in the proposed controllers depends only on the desired signals, and the smooth robust compensator using the hyperbolic tangent function is employed to counteract the CNN approximation errors and external disturbances. The adaptive NN controller-II can efficiently avoid the over-estimation problem (i.e., the bound of the CNNs output is much larger than that of the approximated unknown function, and hence, the control input may be very large) existing in the adaptive NN controller-I. Both adaptive output feedback controllers using CNN can guarantee that all signals in the resulting closed-loop system are uniformly ultimately bounded. For performance comparisons, the standard adaptive controller using the linear parameterization of spacecraft attitude motion is also developed. Simulation studies are presented to show the advantages of the proposed CNN-based output feedback approach over the standard adaptive output feedback approach.

  11. Feedback in Videogame-Based Adaptive Training

    Science.gov (United States)

    Rivera, Iris Daliz

    2010-01-01

    The field of training has been changing rapidly due to advances in technology such as videogame-based adaptive training. Videogame-based adaptive training has provided flexibility and adaptability for training in cost-effective ways. Although this method of training may have many benefits for the trainee, current research has not kept up to pace…

  12. Feedback in Videogame-Based Adaptive Training

    Science.gov (United States)

    Rivera, Iris Daliz

    2010-01-01

    The field of training has been changing rapidly due to advances in technology such as videogame-based adaptive training. Videogame-based adaptive training has provided flexibility and adaptability for training in cost-effective ways. Although this method of training may have many benefits for the trainee, current research has not kept up to pace…

  13. Linear systems a measurement based approach

    CERN Document Server

    Bhattacharyya, S P; Mohsenizadeh, D N

    2014-01-01

    This brief presents recent results obtained on the analysis, synthesis and design of systems described by linear equations. It is well known that linear equations arise in most branches of science and engineering as well as social, biological and economic systems. The novelty of this approach is that no models of the system are assumed to be available, nor are they required. Instead, a few measurements made on the system can be processed strategically to directly extract design values that meet specifications without constructing a model of the system, implicitly or explicitly. These new concepts are illustrated by applying them to linear DC and AC circuits, mechanical, civil and hydraulic systems, signal flow block diagrams and control systems. These applications are preliminary and suggest many open problems. The results presented in this brief are the latest effort in this direction and the authors hope these will lead to attractive alternatives to model-based design of engineering and other systems.

  14. An Industrial Model Based Disturbance Feedback Control Scheme

    DEFF Research Database (Denmark)

    Kawai, Fukiko; Nakazawa, Chikashi; Vinther, Kasper

    2014-01-01

    This paper presents a model based disturbance feedback control scheme. Industrial process systems have been traditionally controlled by using relay and PID controller. However these controllers are affected by disturbances and model errors and these effects degrade control performance. The authors...... propose a new control method that can decrease the negative impact of disturbance and model errors. The control method is motivated by industrial practice by Fuji Electric. Simulation tests are examined with a conventional PID controller and the disturbance feedback control. The simulation results...

  15. A Direct Feedback Control Based on Fuzzy Recurrent Neural Network

    Institute of Scientific and Technical Information of China (English)

    李明; 马小平

    2002-01-01

    A direct feedback control system based on fuzzy-recurrent neural network is proposed, and a method of training weights of fuzzy-recurrent neural network was designed by applying modified contract mapping genetic algorithm. Computer simul ation results indicate that fuzzy-recurrent neural network controller has perfect dynamic and static performances .

  16. Towards App-based Formative Feedback to Support Summarizing Skills

    NARCIS (Netherlands)

    Van Rosmalen, Peter; Kester, Liesbeth; Boshuizen, Els

    2013-01-01

    Van Rosmalen, P., Kester, L., & Boshuizen, H. P. A. (2013). Towards App‐based Formative Feedback to Support Summarizing Skills. ECTEL 2013: Workshop on Technology-Enhanced Formative Assessment (TEFA). September, 17-18, 2013, Paphos, Cyprus. Available online at: http://www.kbs.uni-hannover.de/tefa201

  17. On the Capability of Measurement-Based Quantum Feedback

    CERN Document Server

    Qi, Bo; Guo, Lei

    2010-01-01

    As a key method in dealing with uncertainties, feedback has been understood fairly well in classical control theory. But for quantum control systems, the capability of measurement-based feedback control (MFC) has not been investigated systematically. In contrast to the control of classical systems where the measurement effect is negligible, the quantum measurement will cause a quantum state to collapse, which will inevitably introduce additional uncertainties besides the system initial uncertainty. Therefore, there is a complicated tradeoff between the uncertainty introduced and the information gained by the measurement, and thus a theoretical investigation of the capability of MFC is of fundamental importance. In this paper, inspired by both the Heisenberg uncertainty principle for quantum systems and the investigation of the feedback capability for classical systems, we try to answer the following three basic questions: (i) How to choose the measurement channel appropriately? (ii) Is the MFC still superior ...

  18. Feedback in Web-based assignments

    NARCIS (Netherlands)

    Collis, Betty; de Boer, Willem; Slotman, K.M.J.

    2001-01-01

    Abstract In the Faculty of Educational Science and Technology at the University of Twente an educational concept based on the ideas of increased flexibility in learning options and the active student, has been in place since 1998. In this approach, many courses have moved from a model of lectures

  19. 离散线性多输入系统的切换反馈镇定%Switching Feedback Stabilization for Discrete Linear Multiple-input Systems

    Institute of Scientific and Technical Information of China (English)

    石海彬; 冯纯伯

    2005-01-01

    New idea of stabilization for discrete linear multiple-input system is proposed based on switching technique and single-input control. The system discussed here denotes coupled singleinput objects to be controlled. The central processing unit chooses an object at each discrete instant according to periodic switching strategy and controls it by local state feedback. Stabilization of a multiple-input system is turned into stabilization of single-input systems under periodic switching strategy, which is easy to be realized in practice. On the other hand, only one central processing unit can realize all local controllers, which decreases the cost and increases the usage of the resources.

  20. EXACT LINEARIZATION BASED MULTIPLE-SUBSPACE ITERATIVE RESOLUTION TO AFFINE NONLINEAR CONTROL SYSTEM

    Institute of Scientific and Technical Information of China (English)

    XU Zi-xiang; ZHOU De-yun; DENG Zi-chen

    2006-01-01

    To the optimal control problem of affine nonlinear system, based on differential geometry theory, feedback precise linearization was used. Then starting from the simulative relationship between computational structural mechanics and optimal control,multiple-substructure method was inducted to solve the optimal control problem which was linearized. And finally the solution to the original nonlinear system was found. Compared with the classical linearizational method of Taylor expansion, this one diminishes the abuse of error expansion with the enlargement of used region.

  1. Hippocampus Segmentation Based on Local Linear Mapping

    Science.gov (United States)

    Pang, Shumao; Jiang, Jun; Lu, Zhentai; Li, Xueli; Yang, Wei; Huang, Meiyan; Zhang, Yu; Feng, Yanqiu; Huang, Wenhua; Feng, Qianjin

    2017-04-01

    We propose local linear mapping (LLM), a novel fusion framework for distance field (DF) to perform automatic hippocampus segmentation. A k-means cluster method is propose for constructing magnetic resonance (MR) and DF dictionaries. In LLM, we assume that the MR and DF samples are located on two nonlinear manifolds and the mapping from the MR manifold to the DF manifold is differentiable and locally linear. We combine the MR dictionary using local linear representation to present the test sample, and combine the DF dictionary using the corresponding coefficients derived from local linear representation procedure to predict the DF of the test sample. We then merge the overlapped predicted DF patch to obtain the DF value of each point in the test image via a confidence-based weighted average method. This approach enabled us to estimate the label of the test image according to the predicted DF. The proposed method was evaluated on brain images of 35 subjects obtained from SATA dataset. Results indicate the effectiveness of the proposed method, which yields mean Dice similarity coefficients of 0.8697, 0.8770 and 0.8734 for the left, right and bi-lateral hippocampus, respectively.

  2. An Improved Piecewise Linear Chaotic Map Based Image Encryption Algorithm

    Directory of Open Access Journals (Sweden)

    Yuping Hu

    2014-01-01

    Full Text Available An image encryption algorithm based on improved piecewise linear chaotic map (MPWLCM model was proposed. The algorithm uses the MPWLCM to permute and diffuse plain image simultaneously. Due to the sensitivity to initial key values, system parameters, and ergodicity in chaotic system, two pseudorandom sequences are designed and used in the processes of permutation and diffusion. The order of processing pixels is not in accordance with the index of pixels, but it is from beginning or end alternately. The cipher feedback was introduced in diffusion process. Test results and security analysis show that not only the scheme can achieve good encryption results but also its key space is large enough to resist against brute attack.

  3. An Improved Piecewise Linear Chaotic Map Based Image Encryption Algorithm

    Science.gov (United States)

    Hu, Yuping; Wang, Zhijian

    2014-01-01

    An image encryption algorithm based on improved piecewise linear chaotic map (MPWLCM) model was proposed. The algorithm uses the MPWLCM to permute and diffuse plain image simultaneously. Due to the sensitivity to initial key values, system parameters, and ergodicity in chaotic system, two pseudorandom sequences are designed and used in the processes of permutation and diffusion. The order of processing pixels is not in accordance with the index of pixels, but it is from beginning or end alternately. The cipher feedback was introduced in diffusion process. Test results and security analysis show that not only the scheme can achieve good encryption results but also its key space is large enough to resist against brute attack. PMID:24592159

  4. Robust H∞ Stabilization of Uncertain Linear Time-Delay System with Delayed/Undelayed State Feedback Controllers

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper focuses on the H∞ controller design for linear systems with time-varying delays and norm bounded parameter perturbetions in the system state and control/disturbance. On the existence of delayed/undelayed full state feedback controllers, we present a sufficient condition and give a design method in the form of Riccati equation. The controller can not only stabilize the time-delay system, but also make the H∞ norm of the closed-loop system be less than a given bound. This result practically generalizes the related results in current literature.

  5. Feedback Gating Control for Network Based on Macroscopic Fundamental Diagram

    Directory of Open Access Journals (Sweden)

    YangBeibei Ji

    2016-01-01

    Full Text Available Empirical data from Yokohama, Japan, showed that a macroscopic fundamental diagram (MFD of urban traffic provides for different network regions a unimodal low-scatter relationship between network vehicle density and network space-mean flow. This provides new tools for network congestion control. Based on MFD, this paper proposed a feedback gating control policy which can be used to mitigate network congestion by adjusting signal timings of gating intersections. The objective of the feedback gating control model is to maximize the outflow and distribute the allowed inflows properly according to external demand and capacity of each gating intersection. An example network is used to test the performance of proposed feedback gating control model. Two types of background signalization types for the intersections within the test network, fixed-time and actuated control, are considered. The results of extensive simulation validate that the proposed feedback gating control model can get a Pareto improvement since the performance of both gating intersections and the whole network can be improved significantly especially under heavy demand situations. The inflows and outflows can be improved to a higher level, and the delay and queue length at all gating intersections are decreased dramatically.

  6. Observer-based linear parameter varying H∞ tracking control for hypersonic vehicles

    Directory of Open Access Journals (Sweden)

    Yiqing Huang

    2016-11-01

    Full Text Available This article aims to develop observer-based linear parameter varying output feedback H∞ tracking controller for hypersonic vehicles. Due to the complexity of an original nonlinear model of the hypersonic vehicle dynamics, a slow–fast loop linear parameter varying polytopic model is introduced for system stability analysis and controller design. Then, a state observer is developed by linear parameter varying technique in order to estimate the unmeasured attitude angular for slow loop system. Also, based on the designed linear parameter varying state observer, a kind of attitude tracking controller is presented to reduce tracking errors for all bounded reference attitude angular inputs. The closed-loop linear parameter varying system is proved to be quadratically stable by Lypapunov function technique. Finally, simulation results show that the developed linear parameter varying H∞ controller has good tracking capability for reference commands.

  7. Fast ALS-based tensor factorization for context-aware recommendation from implicit feedback

    CERN Document Server

    Hidasi, Balázs

    2012-01-01

    Albeit, the implicit feedback based recommendation problem - when only the user history is available but there are no ratings - is the most typical setting in real-world applications, it is much less researched than the explicit feedback case. State-of-the-art algorithms that are efficient on the explicit case cannot be straightforwardly transformed to the implicit case if scalability should be maintained. There are few if any implicit feedback benchmark datasets, therefore new ideas are usually experimented on explicit benchmarks. In this paper, we propose a generic context-aware implicit feedback recommender algorithm, coined iTALS. iTALS apply a fast, ALS-based tensor factorization learning method that scales linearly with the number of non-zero elements in the tensor. The method also allows us to incorporate diverse context information into the model while maintaining its computational efficiency. In particular, we present two such context-aware implementation variants of iTALS. The first incorporates sea...

  8. Improved methods in neural network-based adaptive output feedback control, with applications to flight control

    Science.gov (United States)

    Kim, Nakwan

    Utilizing the universal approximation property of neural networks, we develop several novel approaches to neural network-based adaptive output feedback control of nonlinear systems, and illustrate these approaches for several flight control applications. In particular, we address the problem of non-affine systems and eliminate the fixed point assumption present in earlier work. All of the stability proofs are carried out in a form that eliminates an algebraic loop in the neural network implementation. An approximate input/output feedback linearizing controller is augmented with a neural network using input/output sequences of the uncertain system. These approaches permit adaptation to both parametric uncertainty and unmodeled dynamics. All physical systems also have control position and rate limits, which may either deteriorate performance or cause instability for a sufficiently high control bandwidth. Here we apply a method for protecting an adaptive process from the effects of input saturation and time delays, known as "pseudo control hedging". This method was originally developed for the state feedback case, and we provide a stability analysis that extends its domain of applicability to the case of output feedback. The approach is illustrated by the design of a pitch-attitude flight control system for a linearized model of an R-50 experimental helicopter, and by the design of a pitch-rate control system for a 58-state model of a flexible aircraft consisting of rigid body dynamics coupled with actuator and flexible modes. A new approach to augmentation of an existing linear controller is introduced. It is especially useful when there is limited information concerning the plant model, and the existing controller. The approach is applied to the design of an adaptive autopilot for a guided munition. Design of a neural network adaptive control that ensures asymptotically stable tracking performance is also addressed.

  9. Non-Linear Dynamic Deformation of a Piezothermoelastic Laminate with Feedback Control System

    Directory of Open Access Journals (Sweden)

    Masayuki Ishihara

    2014-03-01

    Full Text Available We study the control of free vibration with large amplitude in a piezothermoelastic laminated beam subjected to a uniform temperature with a feedback control system. The analytical model is the symmetrically cross-ply laminated beam composed of the elastic and piezoelectric layers. On the basis of the von Kármán strain and the classical laminate theory, the governing equations for the dynamic behavior are derived. The dynamic behavior is detected by the electric current in the sensor layer through the direct piezoelectric effect. The electric voltage with the magnitude of the current multiplied by the gain is applied to the actuator layer to constitute a feedback control system. The governing equations are reduced by the Galerkin method to a Liénard equation with respect to the representative deflection, and the equation is found to be dependent on the gain and the configuration of the actuator. By introducing the Liénard's phase plane, the equation is analyzed geometrically, and the essential characteristics of the beam and stabilization of the dynamic deformation are demonstrated.

  10. Resonances of a nonlinear SDOF system with time-delay in linear feedback control

    Energy Technology Data Exchange (ETDEWEB)

    El-Bassiouny, A F [Mathematics Department, Faculty of Science, Benha University, Benha 13518 (Egypt); El-kholy, S [Department of Mathematics, Faculty of Science, Menoufia University, Shebin El-kom (Egypt)], E-mail: atef_elbassiouny@yahoo.com

    2010-01-15

    The primary and subharmonic resonances of a nonlinear single-degree-of-freedom (SDOF) system under feedback control with a time delay have been studied by means of an asymptotic perturbation technique. Both external (forcing) and parametric excitations have been included. By means of the averaging method and multiple scales method, two slow-flow equations for the amplitude and phase of the primary and subharmonic resonances and all other parameters are obtained, respectively. The steady state solutions (fixed points) for the original system are investigated. The stability of the fixed points is examined by using the variational method. The effect of the feedback gains, time-delay, the coefficient of cubic term, the coefficients of external and parametric excitations on the steady state responses are investigated and the results are presented as plots of the steady state response amplitude versus the detuning parameter. The results obtained by the two methods are in excellent agreement. There exist saddle node bifurcations for the case of primary resonance and the solutions lose stability for the case of resonance subharmonic.

  11. Spectral clustering based on local linear approximations

    CERN Document Server

    Arias-Castro, Ery; Lerman, Gilad

    2010-01-01

    In the context of clustering, we assume a generative model where each cluster is the result of sampling points in the neighborhood of an embedded smooth surface, possibly contaminated with outliers. We consider a prototype for a higher-order spectral clustering method based on the residual from a local linear approximation. In an asymptotic setting where the number of points becomes large, we obtain theoretical guaranties for this algorithm and show that, both in terms of separation and robustness to outliers, it outperforms the standard spectral clustering algorithm based on pairwise distances of Ng, Jordan and Weiss (NIPS, 2001). Under some conditions on the dimension of, and the incidence angle at, an intersection, the algorithm is able to recover the intersecting clusters. The optimal choice for some of the tuning parameters depends on the dimension and thickness of the clusters. We provide estimators that come close enough for our purposes. We discuss the cases of clusters of mixed dimensions and of clus...

  12. Chaos Control in Three Dimensional Cancer Model by State Space Exact Linearization Based on Lie Algebra

    Directory of Open Access Journals (Sweden)

    Mohammad Shahzad

    2016-05-01

    Full Text Available This study deals with the control of chaotic dynamics of tumor cells, healthy host cells, and effector immune cells in a chaotic Three Dimensional Cancer Model (TDCM by State Space Exact Linearization (SSEL technique based on Lie algebra. A non-linear feedback control law is designed which induces a coordinate transformation thereby changing the original chaotic TDCM system into a controlled one linear system. Numerical simulation has been carried using Mathematica that witness the robustness of the technique implemented on the chosen chaotic system.

  13. Tutorial on beam-based feedback systems for linacs

    Energy Technology Data Exchange (ETDEWEB)

    Hendrickson, L.; Allison, S.; Gromme, T.; Grossberg, P.; Himel, T.; Krauter, K.; MacKenzie, R.; Ross, M.; Sass, R.; Shoaee, H.

    1994-08-01

    A generalized fast feedback system stabilizes beams in the SLC. It performs measurements and modifies actuator settings to control beam states such as position, angle, energy and intensity on a pulse to pulse basis. An adaptive cascade feature allows communication between a series of linac loops, avoiding overcorrection problems. The system is based on the state space formalism of digital control theory. Due to the database-driven design, new loops are added without requiring software modifications. Recent enhancements support the monitoring and control of nonlinear states such as beam phase using excitation techniques. In over three years of operation, the feedback system has grown from its original eight loops to more than fifty loops, and it has been invaluable in stabilizing the machine.

  14. Model-Based State Feedback Controller Design for a Turbocharged Diesel Engine with an EGR System

    Directory of Open Access Journals (Sweden)

    Tianpu Dong

    2015-05-01

    Full Text Available This paper describes a method for the control of transient exhaust gas recirculation (EGR systems. Firstly, a state space model of the air system is developed by simplifying a mean value model. The state space model is linearized by using linearization theory and validated by the GT-Power data with an operating point of the diesel engine. Secondly, a state feedback controller based on the intake oxygen mass fraction is designed for EGR control. Since direct measurement of the intake oxygen mass fraction is unavailable on the engine, the estimation method for intake oxygen mass fraction has been proposed in this paper. The control strategy is analyzed by using co-simulation with the Matlab/Simulink and GT-Powers software. Finally, the whole control system is experimentally validated against experimental data of a turbocharged diesel engine. The control effect of the state feedback controller compared with PID controller proved to be further verify the feasibility and advantages of the proposed state feedback controller.

  15. Feed Drive Based upon Linear Motor for Ultraprecision Turning Machine

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The characteristics of several different linear motors have been investigated, and the feed drive system with linear motor instead of screw-nut mechanism has been built for a submicro ultraprecision turning machine. In the control system for the feed drive system arranged as "T", both P-position and PI-speed control loops are used. The feedback variable is obtained from a double frequecy laser interferometor. Experiments show that the feed drive with linear motor is simple in construction, and that its dynamics is better than others. So the machining accuracy of the workpiece machined has been successfully improved.

  16. Robust chaos synchronization based on adaptive fuzzy delayed feedback $\\mathcal{H}_{∞}$ control

    Indian Academy of Sciences (India)

    Choon Ki Ahn

    2012-03-01

    In this paper, we propose a new adaptive $\\mathcal_{∞}$ synchronization strategy, called an adaptive fuzzy delayed feedback $\\mathcal_{∞}$ synchronization (AFDFHS) strategy, for chaotic systems with uncertain parameters and external disturbances. Based on Lyapunov–Krasovskii theory, Takagi–Sugeno (T–S) fuzzy model and adaptive delayed feedback $\\mathcal_{∞}$ control scheme, the AFDFHS controller is presented such that the synchronization error system is asymptotically stable with a guaranteed $\\mathcal_{∞}$ performance. It is shown that the design of the AFDFHS controller with adaptive law can be achieved by solving a linear matrix inequality (LMI), which can be easily facilitated by using some standard numerical packages. An illustrative example is given to demonstrate the effectiveness of the proposed AFDFHS approach.

  17. All-Fiber Configuration Laser Self-Mixing Doppler Velocimeter Based on Distributed Feedback Fiber Laser.

    Science.gov (United States)

    Wu, Shuang; Wang, Dehui; Xiang, Rong; Zhou, Junfeng; Ma, Yangcheng; Gui, Huaqiao; Liu, Jianguo; Wang, Huanqin; Lu, Liang; Yu, Benli

    2016-07-27

    In this paper, a novel velocimeter based on laser self-mixing Doppler technology has been developed for speed measurement. The laser employed in our experiment is a distributed feedback (DFB) fiber laser, which is an all-fiber structure using only one Fiber Bragg Grating to realize optical feedback and wavelength selection. Self-mixing interference for optical velocity sensing is experimentally investigated in this novel system, and the experimental results show that the Doppler frequency is linearly proportional to the velocity of a moving target, which agrees with the theoretical analysis commendably. In our experimental system, the velocity measurement can be achieved in the range of 3.58 mm/s-2216 mm/s with a relative error under one percent, demonstrating that our novel all-fiber configuration velocimeter can implement wide-range velocity measurements with high accuracy.

  18. A global hybrid coupled model based on Atmosphere-SST feedbacks

    CERN Document Server

    Cimatoribus, Andrea A; Dijkstra, Henk A

    2011-01-01

    A global hybrid coupled model is developed, with the aim of studying the effects of ocean-atmosphere feedbacks on the stability of the Atlantic meridional overturning circulation. The model includes a global ocean general circulation model and a statistical atmosphere model. The statistical atmosphere model is based on linear regressions of data from a fully coupled climate model on sea surface temperature both locally and hemispherically averaged, being the footprint of Atlantic meridional overturning variability. It provides dynamic boundary conditions to the ocean model for heat, freshwater and wind-stress. A basic but consistent representation of ocean-atmosphere feedbacks is captured in the hybrid coupled model and it is more than ten times faster than the fully coupled climate model. The hybrid coupled model reaches a steady state with a climate close to the one of the fully coupled climate model, and the two models also have a similar response (collapse) of the Atlantic meridional overturning circulati...

  19. Event-triggered Dynamic Output Feedback Control for Switched Linear Systems

    NARCIS (Netherlands)

    Qi, Yiwen; Cao, Ming

    2016-01-01

    Switched linear systems and their control have been an active research field in the past two decades; however, no systematic results have been reported in the literature on how such systems behave when event-triggered control is introduced. While the potential advantage of introducing event-triggere

  20. ERF Based Precision Linear Drive System

    Science.gov (United States)

    Tönshoff, Hans Kurt; Stegmann, Axel

    The design of clutches using electrorheological fluids (ERF) or magnetorheological suspensions (MRS) offers a new approach to precision linear drive systems based on the ‘inch-worm’ principle. This principle needs two clutches or controllable clamps and one (or more) elements to vary the distance between these clamps. To perform a caterpillar-like motion the actuators are controlled in a cyclic mode. This paper presents design elements, system structure and first results of motion performance of a prototype drive system. The presented linear drive combines the high resolution of piezo actuators, the unlimited travel of the ‘inch-worm’ principle and the clutch effect of ERF without a substantial mechanical excitation. The motion of the two clamps is controlled to move a stage in point to point mode or to follow a given velocity profile. Using two piezo actuators the stage can move continuously. Pre-loaded piezo actuators control the distances between the two clamps and the central slide. Each ERF clamp is designed as a set of thin parallel steel plate electrodes which interlock with a set of ground plates. Drive force limits are given by the maximum yield force of the clamps as well as by the relation of the actuator expansion and the ERF/MRS shear stiffness in “solid” mode.

  1. Delay-dependent observer-based stabilizing controller design for linear multiple state-delayed systems

    Institute of Scientific and Technical Information of China (English)

    Dejin WANG

    2003-01-01

    This article concerns a coupled LMIs approach to delay-dependent observer-based output feedback stabilizing controller design for linear continuous-time systems with multiple state delays. The advantage of our proposed delay-dependent coupled LMIs criterion lies in that: (1) it can optimize one of multiple time delays with others selected properly, and at the same time, the feedback-gain and observer-gain can be obtained, respectively. (2) it is less conservative than the existing delay-independent ones in the literature. Algorithm to solve the coupled LMIs is also given. Numerical examples illustrate the effectiveness of our method.

  2. Watermark Resistance Analysis Based On Linear Transformation

    Directory of Open Access Journals (Sweden)

    N.Karthika Devi

    2012-06-01

    Full Text Available Generally, digital watermark can be embedded in any copyright image whose size is not larger than it. The watermarking schemes can be classified into two categories: spatial domain approach or transform domain approach. Previous works have shown that the transform domain scheme is typically more robust to noise, common image processing, and compression when compared with the spatial transform scheme. Improvements in performance of watermarking schemes can be obtained by exploiting the characteristics of the human visual system (HVS in the watermarking process. We propose a linear transformation based watermarking algorithm. The watermarking bits are embedded into cover image to produce watermarked image. The efficiency of watermark is checked using pre-defined attacks. Attack resistance analysis is done using BER (Bit Error Rate calculation. Finally, the Quality of the watermarked image can be obtained.

  3. Quantum limits on the detection sensitivity of a linear detector with feedback

    Science.gov (United States)

    Gao, Yang

    2017-03-01

    We show that the detection sensitivity of a linear detector is lower bounded by some quantum limits. For the force sensitivity, which is relevant for atomic force microscopes, the lower bound is given by the so-called ultimate quantum limit (UQL). For the displacement sensitivity, which is relevant for detecting gravitational waves, a generalized lower bound that can overcome the usual UQL is obtained.

  4. MEASURING SYSTEM FOR FEEDBACK REALIZATION IN COORDINATE POSITIONERS IN LINEAR STEP-BY-STEP MOTORS

    Directory of Open Access Journals (Sweden)

    V. V. Jarski

    2009-01-01

    Full Text Available The paper considers development of non-hysteresis position sensor for a planar direct drive in a linear step-by-step motor (LSM on the basis of the Hall-effect converters. A magnetic equivalent circuit, a transformation mathematical model for the LSM inductor position relatively to a stator are developed in the paper. The paper contains an analysis of experimental results.

  5. Novel, ERP-based, concealed information detection: Combining recognition-based and feedback-evoked ERPs.

    Science.gov (United States)

    Sai, Liyang; Lin, Xiaohong; Rosenfeld, J Peter; Sang, Biao; Hu, Xiaoqing; Fu, Genyue

    2016-02-01

    The present study introduced a novel variant of the concealed information test (CIT), called the feedback-CIT. By providing participants with feedbacks regarding their memory concealment performance during the CIT, we investigated the feedback-related neural activity underlying memory concealment. Participants acquired crime-relevant memories via enacting a lab crime, and were tested with the feedback-CIT while EEGs were recorded. We found that probes (e.g., crime-relevant memories) elicited larger recognition-P300s than irrelevants among guilty participants. Moreover, feedback-related negativity (FRN) and feedback-P300 could also discriminate probes from irrelevants among guilty participants. Both recognition- and feedback-ERPs were highly effective in distinguishing between guilty and innocent participants (recognition-P300: AUC=.73; FRN: AUC=.95; feedback-P300: AUC=.97). This study sheds new light on brain-based memory detection, such that feedback-related neural signals can be employed to detect concealed memories.

  6. Optimal Trajectory Planning and Linear Velocity Feedback Control of a Flexible Piezoelectric Manipulator for Vibration Suppression

    Directory of Open Access Journals (Sweden)

    Junqiang Lou

    2015-01-01

    Full Text Available Trajectory planning is an effective feed-forward control technology for vibration suppression of flexible manipulators. However, the inherent drawback makes this strategy inefficient when dealing with modeling errors and disturbances. An optimal trajectory planning approach is proposed and applied to a flexible piezoelectric manipulator system in this paper, which is a combination of feed-forward trajectory planning method and feedback control of piezoelectric actuators. Specifically, the joint controller is responsible for the trajectory tracking and gross vibration suppression of the link during motion, while the active controller of actuators is expected to deal with the link vibrations after joint motion. In the procedure of trajectory planning, the joint angle of the link is expressed as a quintic polynomial function. And the sum of the link vibration energy is chosen as the objective function. Then, genetic algorithm is used to determine the optimal trajectory. The effectiveness of the proposed method is validated by simulation and experiments. Both the settling time and peak value of the link vibrations along the optimal trajectory reduce significantly, with the active control of the piezoelectric actuators.

  7. Neural-Based Adaptive Output-Feedback Control for a Class of Nonstrict-Feedback Stochastic Nonlinear Systems.

    Science.gov (United States)

    Wang, Huanqing; Liu, Kefu; Liu, Xiaoping; Chen, Bing; Lin, Chong

    2015-09-01

    In this paper, we consider the problem of observer-based adaptive neural output-feedback control for a class of stochastic nonlinear systems with nonstrict-feedback structure. To overcome the design difficulty from the nonstrict-feedback structure, a variable separation approach is introduced by using the monotonically increasing property of system bounding functions. On the basis of the state observer, and by combining the adaptive backstepping technique with radial basis function neural networks' universal approximation capability, an adaptive neural output feedback control algorithm is presented. It is shown that the proposed controller can guarantee that all the signals in the closed-loop system are semi-globally uniformly ultimately bounded in the sense of mean quartic value. Simulation results are provided to show the effectiveness of the proposed control scheme.

  8. A METHOD FOR SOLVING LINEAR PROGRAMMING PROBLEMS WITH FUZZY PARAMETERS BASED ON MULTIOBJECTIVE LINEAR PROGRAMMING TECHNIQUE

    OpenAIRE

    Zangiabadi, M.; H. R. MALEKI

    2007-01-01

    In the real-world optimization problems, coefficients of the objective function are not known precisely and can be interpreted as fuzzy numbers. In this paper we define the concepts of optimality for linear programming problems with fuzzy parameters based on those for multiobjective linear programming problems. Then by using the concept of comparison of fuzzy numbers, we transform a linear programming problem with fuzzy parameters to a multiobjective linear programming problem. To this end, w...

  9. Reservation-based feedback scheduling of MPC tasks

    Institute of Scientific and Technical Information of China (English)

    Zhou Pingfang; Xie Jianying

    2007-01-01

    A reservation-based feedback scheduling (FS-CBS) of a set of model predictive control (MPC) tasks is presented to optimize the global control performance subject to limited computational resource. Implemented as anytime algorithm,MPC task allows computation time to be traded for control performance. Each MPC task is assigned with a constant bandwidth server (CBS), whose reserved processor time is adjusted dynamically. The FS-CBS is shown robust against the varying of execution time of MPC tasks at runtime. Simulation results illustrate its effectiveness.

  10. Absolute small-angle measurement based on optical feedback interferometry

    Institute of Scientific and Technical Information of China (English)

    Jingang Zhong; Xianhua Zhang; Zhixiang Ju

    2008-01-01

    We present a simple but effective method for small-angle measurement based on optical feedback inter-ferometry (or laser self-mixing interferometry). The absolute zero angle can be defined at the biggest fringe amplitude point, so this method can also achieve absolute angle measurement. In order to verify the method, we construct an angle measurement system. The Fourier-transform method is used to analysis the interference signal. Rotation angles are experimentally measured with a resolution of 10-6 rad and a measurement range of approximately from -0.0007 to +0.0007 rad.

  11. Linear Strategy for Boolean Ring Based Theorem Proving

    Institute of Scientific and Technical Information of China (English)

    WU Jinzhao; LIU Zhuojun

    2000-01-01

    Two inference rules are discussed in boolean ring based theorem proving, and linear strategy is developed. It is shown that both of them are complete for linear strategy. Moreover, by introducing a partial ordering on atoms, pseudo O-linear and O-linear strategies are presented. The former is complete, the latter, however, is complete for clausal theorem proving.

  12. Effect of vibrotactile feedback on an EMG-based proportional cursor control system.

    Science.gov (United States)

    Li, Shunchong; Chen, Xingyu; Zhang, Dingguo; Sheng, Xinjun; Zhu, Xiangyang

    2013-01-01

    Surface electromyography (sEMG) has been introduced into the bio-mechatronics systems, however, most of them are lack of the sensory feedback. In this paper, the effect of vibrotactile feedback for a myoelectric cursor control system is investigated quantitatively. Simultaneous and proportional control signals are extracted from EMG using a muscle synergy model. Different types of feedback including vibrotactile feedback and visual feedback are added, assessed and compared with each other. The results show that vibrotactile feedback is capable of improving the performance of EMG-based human machine interface.

  13. Integral force feedback control with input shaping: Application to piezo-based scanning systems in ECDLs

    Science.gov (United States)

    Zhang, Meng; Liu, Zhigang; Zhu, Yu; Bu, Mingfan; Hong, Jun

    2017-07-01

    In this paper, a hybrid control system is developed by integrating the closed-loop force feedback and input shaping method to overcome the problem of the hysteresis and dynamic behavior in piezo-based scanning systems and increase the scanning speed of tunable external cavity diode lasers. The flexible hinge and piezoelectric actuators are analyzed, and a dynamic model of the scanning systems is established. A force sensor and an integral controller are utilized in integral force feedback (IFF) to directly augment the damping of the piezoelectric scanning systems. Hysteresis has been effectively eliminated, but the mechanical resonance is still evident. Noticeable residual vibration occurred after the inflection points and then gradually disappeared. For the further control of mechanical resonance, based on the theory of minimum-acceleration trajectory planning, the time-domain input shaping method was developed. The turning sections of a scanning trajectory are replaced by smooth curves, while the linear sections are retained. The IFF method is combined with the input shaping method to control the non-linearity and mechanical resonance in high-speed piezo-based scanning systems. Experiments are conducted, and the results demonstrate the effectiveness of the proposed control approach.

  14. Dynamic Output Feedback Based Active Decentralized Fault-Tolerant Control for Reconfigurable Manipulator with Concurrent Failures

    Directory of Open Access Journals (Sweden)

    Yuanchun Li

    2015-01-01

    Full Text Available The goal of this paper is to describe an active decentralized fault-tolerant control (ADFTC strategy based on dynamic output feedback for reconfigurable manipulators with concurrent actuator and sensor failures. Consider each joint module of the reconfigurable manipulator as a subsystem, and treat the fault as the unknown input of the subsystem. Firstly, by virtue of linear matrix inequality (LMI technique, the decentralized proportional-integral observer (DPIO is designed to estimate and compensate the sensor fault online; hereafter, the compensated system model could be derived. Then, the actuator fault is estimated similarly by another DPIO using LMI as well, and the sufficient condition of the existence of H∞ fault-tolerant controller in the dynamic output feedback is presented for the compensated system model. Furthermore, the dynamic output feedback controller is presented based on the estimation of actuator fault to realize active fault-tolerant control. Finally, two 3-DOF reconfigurable manipulators with different configurations are employed to verify the effectiveness of the proposed scheme in simulation. The main advantages of the proposed scheme lie in that it can handle the concurrent faults act on the actuator and sensor on the same joint module, as well as there is no requirement of fault detection and isolation process; moreover, it is more feasible to the modularity of the reconfigurable manipulator.

  15. An FPGA-based Bunch-by-Bunch Position and Angle Feedback System at ATF2

    CERN Document Server

    Christian, G B; Bett, D R; Burrows, P N; Constance, B; Davis, M R; Gerbershagen, A; Perry, C; Resta Lopez, J

    2011-01-01

    The FONT5 intra-train feedback system serves as a prototype for an interaction point beam-based feedback system for future electron-positron colliders, such as the International Linear Collider. The system has been tested on the KEK Accelerator Test Facility (ATF) and is deployed to stabilise the beam orbit at the ATF2. The goal of this system is to correct both position and angle jitter in the vertical plane, providing stability of ~1 micron at the entrance to the ATF2 final-focus system. The system comprises three stripline beam position monitors (BPMs) and two stripline kickers, custom low-latency analogue front-end BPM processors, a custom FPGA-based digital processing board with fast ADCs, and custom kicker-drive amplifiers. An overview of the hardware, and the latest results from beam tests at ATF2, will be presented. The total latency of the system with coupled position and angle feedback loops operating simultaneously was measured to be approximately 140 ns. The greatest degree of correction observed ...

  16. Analysis of VCO based noise shaping ADCs linearized by PWM modulation

    OpenAIRE

    Hernandez, Luis; Prefasi, , Enrique; Paton , Susana; Rombouts, Pieter

    2012-01-01

    Nonlinearity is one of the main problems associated with VCO based noise shaping ADCs. Their open loop architecture does not permit correction of the nonlinear voltage to frequency response of the VCO by feedback. Recently, linearization of a VCO ADC by Pulse Width Modulation (PWM) precoding has been proposed. Here, the input signal is encoded by a PWM modulator to drive the VCO with a 2-level signal, thus eliminating the nonlinearity of the VCO. This paper analyzes the remaining inherent dis...

  17. A State Feedback Controller Used to Solve an Ill-posed Linear System by a GL(n, R Iterative Algorithm

    Directory of Open Access Journals (Sweden)

    Chein-Shan Liu

    2013-11-01

    Full Text Available Starting from a quadratic invariant manifold in terms of the residual vector ${extbf r}={extbf B}{extbf x}-{extbf b}$ for an $n$-dimensional ill-posed linear algebraic equations system ${extbf B}{extbf x}={extbf b}$, we derive an ODEs system for ${extbf x}$ which is equipped with a state feedback controller to enforce the orbit of the state vector ${extbf x}$ on a specified manifold, whose residual-norm is exponentially decayed. To realize the above idea we develop a very powerful implicit scheme based on the novel $GL(n,{mathbb R}$ Lie-group method to integrate the resultant differential algebraic equation (DAE. Through numerical tests of inverse problems we find that the present Lie-group DAE algorithm can significantly accelerate the convergence speed, and is robust enough against the random noise.

  18. Theoretical design for a class of chaotic stream cipher based on nonlinear coupled feedback

    Institute of Scientific and Technical Information of China (English)

    Hu Guojie; Wang Lin; Feng Zhengjin

    2005-01-01

    A class of chaotic map called piecewise-quadratic-equation map to design feedback stream cipher is proposed.Such map can generate chaotic signals that have uniform distribution function, δ-like autocorrelation function. Compared with the piecewise-linear map, this map provides enhanced security in that they can maintain the original perfect statistical properties, as well as overcome the defect of piecewise-linearity and expand the key space. This paper presents a scheme to improve the local complexity of the chaotic stream cipher based on the piecewise-quadratic-equationmap.Both the theoretic analysis and the results of simulation show that this scheme improves the microstructure of the phasespace graph on condition that the good properties of the original scheme are remained.

  19. Attention Paid to Feedback Provided by a Computer-Based Assessment for Learning on Information Literacy

    Science.gov (United States)

    Timmers, Caroline; Veldkamp, Bernard

    2011-01-01

    Three studies are presented on attention paid to feedback provided by a computer-based assessment for learning on information literacy. Results show that the attention paid to feedback varies greatly. In general the attention focuses on feedback of incorrectly answered questions. In each study approximately fifty percent of the respondents paid…

  20. The Effect of Emotional Feedback on Behavioral Intention to Use Computer Based Assessment

    Science.gov (United States)

    Terzis, Vasileios; Moridis, Christos N.; Economides, Anastasios A.

    2012-01-01

    This study introduces emotional feedback as a construct in an acceptance model. It explores the effect of emotional feedback on behavioral intention to use Computer Based Assessment (CBA). A female Embodied Conversational Agent (ECA) with empathetic encouragement behavior was displayed as emotional feedback. More specifically, this research aims…

  1. Attention Paid to Feedback Provided by a Computer-Based Assessment for Learning on Information Literacy

    Science.gov (United States)

    Timmers, Caroline; Veldkamp, Bernard

    2011-01-01

    Three studies are presented on attention paid to feedback provided by a computer-based assessment for learning on information literacy. Results show that the attention paid to feedback varies greatly. In general the attention focuses on feedback of incorrectly answered questions. In each study approximately fifty percent of the respondents paid…

  2. Linear thermal circulator based on Coriolis forces.

    Science.gov (United States)

    Li, Huanan; Kottos, Tsampikos

    2015-02-01

    We show that the presence of a Coriolis force in a rotating linear lattice imposes a nonreciprocal propagation of the phononic heat carriers. Using this effect we propose the concept of Coriolis linear thermal circulator which can control the circulation of a heat current. A simple model of three coupled harmonic masses on a rotating platform permits us to demonstrate giant circulating rectification effects for moderate values of the angular velocities of the platform.

  3. Control of Forward converter by state feedback linearization%Forward变换器的精确线性化控制

    Institute of Scientific and Technical Information of China (English)

    李昂

    2013-01-01

    In order to improve the control performance of the Forward converter, exact linearization design approach is proposed to apply to converter control. Firstly, the affine nonlinear system models for differential geometry methods are established with the switching function and average switch period operator. Then, the models are proved in theory to meet conditions for exact linearization. For the linear system of nonlinear coordinate transformation, quadratic optimal control strategy is used. The nonlinear state feedback control laws are deduced. The corresponding experiment results show that the system has good static and dynamic performance, and the effectiveness and correctness of the control method are verified.%为了提高Forward变换器非线性系统的控制性能,采用了精确线性化控制方法.首先采用开关函数和开关周期平均算子建立适合微分几何方法的仿射非线性系统模型.从理论上证明了该模型满足系统精确线性化的条件.对非线性坐标变换后得到的线性系统,利用二次型最优控制策略推导出非线性状态反馈控制律.实验结果表明,系统具有良好的静态和动态性能,验证了该控制方法的有效性和正确性.

  4. Wavefront shaping based on three-dimensional optoacoustic feedback

    Science.gov (United States)

    Deán-Ben, X. L.; Estrada, Héctor; Ozbek, Ali; Razansky, Daniel

    2015-07-01

    Wavefront shaping techniques have recently evolved as a promising tool to control the light distribution in optically-scattering media. These techniques are based on spatially-modulating the phase of an incident light beam to create positive interference (focusing) at specific locations in the speckle pattern of the scattered wavefield. The optimum phase distribution (mask) of the spatial light modulator that allows focusing at the target location(s) is determined iteratively by monitoring the light intensity at such target. In this regard, optoacoustic (photoacoustic) imaging may provide the convenient advantage of simultaneous feedback information on light distribution in an entire region of interest. Herein, we showcase that volumetric optoacoustic images can effectively be used as a feedback mechanism in an iterative optimization algorithm allowing controlling the light distribution after propagation through a scattering sample. Experiments performed with absorbing microparticles distributed in a three-dimensional region showcase the feasibility of enhancing the light intensity at specific points. The advantages provided by optoacoustic imaging in terms of spatial and temporal resolution anticipate new capabilities of wavefront shaping techniques in biomedical optics.

  5. FORCE FEEDBACK DATAGLOVE BASED ON PNEUMATIC ARTIFICIAL MUSCLES

    Institute of Scientific and Technical Information of China (English)

    BAO Gang; SUN Zhongsheng; WANG Zuwen

    2006-01-01

    An exoskeleton force feedback dataglove is developed, which uses the pneumatic artificial muscles as actuators. On the basis of the simplified hand model, the motion equation is deduced according to the theory of Denavit-Hartenberg. The model of the equivalent contact forces exerted by the object on the finger is proposed. By the principle of virtual work, the static equilibrium of finger is established. The force Jacobian matrix of finger is calculated, and then the joint torques of the finger when grasping objects are obtained. The theory and structure of the force feedback datagolve are introduced. Based on the theory of motion stabilization of four-bar linkage, the flexion angles of joints are measured. The torques on finger joints caused by the output forces of pneumatic artificial muscles are calculated. The output forces of pneumatic artificial muscle, whose values are controlled by its inner pressure, can be calculated by the joint torques ofthe finger when grasping objects. The arms of force, driving torques and the needed output forces of pneumatic muscle are calculated for each joint of the index finger. The criterion of output force of pneumatic muscle is given.

  6. Qualitative and quantitative feedback in the context of competency-based education.

    Science.gov (United States)

    Tekian, Ara; Watling, Christopher J; Roberts, Trudie E; Steinert, Yvonne; Norcini, John

    2017-09-19

    Research indicates the importance and usefulness of feedback, yet with the shift of medical curricula toward competencies, feedback is not well understood in this context. This paper attempts to identify how feedback fits within a competency-based curriculum. After careful consideration of the literature, the following conclusions are drawn: (1) Because feedback is predicated on assessment, the assessment should be designed to optimize and prevent inaccuracies in feedback; (2) Giving qualitative feedback in the form of a conversation would lend credibility to the feedback, address emotional obstacles and create a context in which feedback is comfortable; (3) Quantitative feedback in the form of individualized data could fulfill the demand for more feedback, help students devise strategies on how to improve, allow students to compare themselves to their peers, recognizing that big data have limitations; and (4) Faculty development needs to incorporate and promote cultural and systems changes with regard to feedback. A better understanding of the role of feedback in competency-based education could result in more efficient learning for students.

  7. Passivity-Based Output-Feedback Control of Turbulent Channel Flow

    CERN Document Server

    Heins, Peter H; Sharma, Ati S

    2016-01-01

    This paper describes a robust linear time-invariant output-feedback control strategy to reduce turbulent fluctuations, and therefore skin-friction drag, in wall-bounded turbulent fluid flows, that nonetheless gives performance guarantees in the nonlinear turbulent regime. The novel strategy is effective in reducing the supply of available energy to feed the turbulent fluctuations, expressed as reducing a bound on the supply rate to a quadratic storage function. The nonlinearity present in the equations that govern the dynamics of the flow is known to be passive and can be considered as a feedback forcing to the linearised dynamics (a Lur'e decomposition). Therefore, one is only required to control the linear dynamics in order to make the system close to passive. The ten most energy-producing spatial modes of a turbulent channel flow were identified. Passivity-based controllers were then generated to control these modes. The controllers require measurements of streamwise and spanwise wall-shear stress, and the...

  8. Multi-Task Collaboration CPS Modeling Based on Immune Feedback

    Directory of Open Access Journals (Sweden)

    Haiying Li

    2013-09-01

    Full Text Available In this paper, a dynamic multi-task collaboration CPS control model based on the self-adaptive immune feedback is proposed and implemented in the smart home environment. First, the internal relations between CPS and the biological immune system are explored via their basic theories. Second, CPS control mechanism is elaborated through the analysis of CPS control structure. Finally, a comprehensive strategy for support is introduced into multi-task collaboration to improve the dynamic cognitive ability. At the same time, the performance of parameters is correspondingly increased by the operator of the antibody concentration and the selective pressure. Furthermore, the model has been put into service in the smart home laboratory. The experimental results show that this model can integrate user’s needs into the environment for properly regulating the home environment.

  9. Novel method based on ant colony optimization for solving ill-conditioned linear systems of equations

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A novel method based on ant colony optimization (ACO), algorithm for solving the ill-conditioned linear systems of equations is proposed. ACO is a parallelized bionic optimization algorithm which is inspired from the behavior of real ants. ACO algorithm is first introduced, a kind of positive feedback mechanism is adopted in ACO. Then, the solution problem of linear systems of equations was reformulated as an unconstrained optimization problem for solution by an ACO algorithm. Finally, the ACO with other traditional methods is applied to solve a kind of multi-dimensional Hilbert ill-conditioned linear equations. The numerical results demonstrate that ACO is effective, robust and recommendable in solving ill-conditioned linear systems of equations.

  10. Feedback in formative OSCEs: comparison between direct observation and video-based formats

    Directory of Open Access Journals (Sweden)

    Noëlle Junod Perron

    2016-11-01

    Full Text Available Introduction: Medical students at the Faculty of Medicine, University of Geneva, Switzerland, have the opportunity to practice clinical skills with simulated patients during formative sessions in preparation for clerkships. These sessions are given in two formats: 1 direct observation of an encounter followed by verbal feedback (direct feedback and 2 subsequent review of the videotaped encounter by both student and supervisor (video-based feedback. The aim of the study was to evaluate whether content and process of feedback differed between both formats. Methods: In 2013, all second- and third-year medical students and clinical supervisors involved in formative sessions were asked to take part in the study. A sample of audiotaped feedback sessions involving supervisors who gave feedback in both formats were analyzed (content and process of the feedback using a 21-item feedback scale. Results: Forty-eight audiotaped feedback sessions involving 12 supervisors were analyzed (2 direct and 2 video-based sessions per supervisor. When adjusted for the length of feedback, there were significant differences in terms of content and process between both formats; the number of communication skills and clinical reasoning items addressed were higher in the video-based format (11.29 vs. 7.71, p=0.002 and 3.71 vs. 2.04, p=0.010, respectively. Supervisors engaged students more actively during the video-based sessions than during direct feedback sessions (self-assessment: 4.00 vs. 3.17, p=0.007; active problem-solving: 3.92 vs. 3.42, p=0.009. Students made similar observations and tended to consider that the video feedback was more useful for improving some clinical skills. Conclusion: Video-based feedback facilitates discussion of clinical reasoning, communication, and professionalism issues while at the same time actively engaging students. Different time and conceptual frameworks may explain observed differences. The choice of feedback format should depend on

  11. Feedback in formative OSCEs: comparison between direct observation and video-based formats

    Science.gov (United States)

    Junod Perron, Noëlle; Louis-Simonet, Martine; Cerutti, Bernard; Pfarrwaller, Eva; Sommer, Johanna; Nendaz, Mathieu

    2016-01-01

    Introduction Medical students at the Faculty of Medicine, University of Geneva, Switzerland, have the opportunity to practice clinical skills with simulated patients during formative sessions in preparation for clerkships. These sessions are given in two formats: 1) direct observation of an encounter followed by verbal feedback (direct feedback) and 2) subsequent review of the videotaped encounter by both student and supervisor (video-based feedback). The aim of the study was to evaluate whether content and process of feedback differed between both formats. Methods In 2013, all second- and third-year medical students and clinical supervisors involved in formative sessions were asked to take part in the study. A sample of audiotaped feedback sessions involving supervisors who gave feedback in both formats were analyzed (content and process of the feedback) using a 21-item feedback scale. Results Forty-eight audiotaped feedback sessions involving 12 supervisors were analyzed (2 direct and 2 video-based sessions per supervisor). When adjusted for the length of feedback, there were significant differences in terms of content and process between both formats; the number of communication skills and clinical reasoning items addressed were higher in the video-based format (11.29 vs. 7.71, p=0.002 and 3.71 vs. 2.04, p=0.010, respectively). Supervisors engaged students more actively during the video-based sessions than during direct feedback sessions (self-assessment: 4.00 vs. 3.17, p=0.007; active problem-solving: 3.92 vs. 3.42, p=0.009). Students made similar observations and tended to consider that the video feedback was more useful for improving some clinical skills. Conclusion Video-based feedback facilitates discussion of clinical reasoning, communication, and professionalism issues while at the same time actively engaging students. Different time and conceptual frameworks may explain observed differences. The choice of feedback format should depend on the educational

  12. Linear peristaltic pump based on electromagnetic actuators

    Directory of Open Access Journals (Sweden)

    Maddoui Lotfi

    2014-01-01

    Full Text Available In this paper a study and design of a linear peristaltic pump are presented. A set of electromagnetic (solenoid actuators is used as the active tools to drag the liquid by crushing an elastic tube. The pump consists of six serially-connected electromagnetic actuators controlled via an electronic board. This may be considered as a simulated peristalsis action of intestines. The dynamic performances of the pump are investigated analytically and experimentally.

  13. Real-time RNN-based acoustic thermometry with feedback control

    Science.gov (United States)

    Hsu, Stephen J.; Nam, Joana H.; Fan, Liexiang; Brunke, Shelby S.; Sekins, K. Michael

    2017-03-01

    A major obstacle to the widespread adoption of HIFU therapy is the development of a suitable method of monitoring the a blation therapy in real-time. While MR-thermometry has emerged as a promising method for HIFU therapy monitoring, acoustic guidance has continuously been sought for reasons of cost and practicality. We have previously demonstrated the potential of acoustic thermometry, by using a recurrent neural network (RNN) to estimate changes in tissue temperature during HIFU ablation therapies. A limitation of this method is that an excessive therapeutic dose can cause multiple, non-linear changes within the ultrasound data, resulting in unreliable temperature estimates from the RNN. Accordingly, we propose a revised method of dosing wherein closed loop feedback is used to provide a controlled and specific dose; not only to ensure an efficacious lesion, but also to preserve the integrity of the ultrasound image, thereby producing accurate temperature estimates from the RNN. This investigation of controlling the thermal dose using feedback was performed on ex vivo bovine liver. The acoustic parameters used as inputs to the RNN were: changes in integrated backscatter intensity, thermal strain, and decorrelation. The therapeutic dose was delivered using a 1.1 MHz, 2D-array HIFU transducer transmitting at regular intervals during a 40-second dose. Interleaved between these regular HIFU dose intervals, volumetric ultrasound images were acquired on a Siemens ACUSON SC2000, with a 4Zlc probe. Feedback was introduced to the system by varying the HIFU duty cycle, in order to minimize the difference between a desired temperature curve (assigned a priori) and the estimated focal temperature values. Two methods were used for obtaining the focal temperature: the first was direct measurement using a 75-micron copper-constantan thermocouple embedded within the liver sample, and the second was temperature estimation as calculated from the RNN-based output temperatures

  14. Ontology-Based Generation of Dynamic Feedback on Physical Activity

    NARCIS (Netherlands)

    Wieringa, Wilko; op den Akker, Harm; Jones, Valerie M.; Hermens, Hermanus J.; op den Akker, Hendrikus J.A.

    2011-01-01

    This article describes a new, AI-inspired telemedicine system for providing feedback on daily activity. Optimising daily levels of physical activity is an important focus in the treatment of chronic illnesses. An ambulatory monitoring and feedback system has been developed to monitor activity and

  15. On the multiscale nature of soil moisture-temperature couplings: the role of seasonality, causation and non-linear feedbacks in land-atmosphere interactions (Invited)

    Science.gov (United States)

    Molini, A.; Casagrande, E.; Mueller, B.

    2013-12-01

    Land-Atmosphere (L-A) interactions, their strength and directionality, are one of the main sources of uncertainty in current climate modeling, with strong implications on the accurate assessment of future climate variability and climate change impacts. Beside from the scarcity of direct observations, major uncertainties derive from the inherent complexity and nonlinearity of these interactions, and from their multi-scale character. Statistical analysis of L-A couplings is traditionally based on linear correlation methods and metrics. However, these approaches are not designed to detect causal connections or non-linear couplings and they poorly perform in presence of non-stationarities. Additionally these methods assess L-A couplings essentially in the time domain, despite the fact that L-A dynamical drivers can act simultaneously over a wide range of different space and time scales. This talk explores the multi-scale nature of L-A interactions, through the example of soil moisture-temperature couplings and soil-moisture memory effects. In several regions of the world, soil moisture can have a dampening effect on temperature due to evaporative cooling. By using spectral decomposition techniques and both newly developed satellite based products and re-analysis, we analyze the contribution of different time scales to the build-up of global soil moisture-temperature coupling hot spots, addressing at the same time the role of seasonality, causation and non-linear feedbacks in land-atmosphere interactions. Finally we focus on the role of fine (sub-monthly) time scales and their interplay with the seasonal scales.

  16. Proprioceptive feedback and brain computer interface (BCI based neuroprostheses.

    Directory of Open Access Journals (Sweden)

    Ander Ramos-Murguialday

    Full Text Available Brain computer interface (BCI technology has been proposed for motor neurorehabilitation, motor replacement and assistive technologies. It is an open question whether proprioceptive feedback affects the regulation of brain oscillations and therefore BCI control. We developed a BCI coupled on-line with a robotic hand exoskeleton for flexing and extending the fingers. 24 healthy participants performed five different tasks of closing and opening the hand: (1 motor imagery of the hand movement without any overt movement and without feedback, (2 motor imagery with movement as online feedback (participants see and feel their hand, with the exoskeleton moving according to their brain signals, (3 passive (the orthosis passively opens and closes the hand without imagery and (4 active (overt movement of the hand and rest. Performance was defined as the difference in power of the sensorimotor rhythm during motor task and rest and calculated offline for different tasks. Participants were divided in three groups depending on the feedback receiving during task 2 (the other tasks were the same for all participants. Group 1 (n = 9 received contingent positive feedback (participants' sensorimotor rhythm (SMR desynchronization was directly linked to hand orthosis movements, group 2 (n = 8 contingent "negative" feedback (participants' sensorimotor rhythm synchronization was directly linked to hand orthosis movements and group 3 (n = 7 sham feedback (no link between brain oscillations and orthosis movements. We observed that proprioceptive feedback (feeling and seeing hand movements improved BCI performance significantly. Furthermore, in the contingent positive group only a significant motor learning effect was observed enhancing SMR desynchronization during motor imagery without feedback in time. Furthermore, we observed a significantly stronger SMR desynchronization in the contingent positive group compared to the other groups during active and

  17. Piecewise Linear Model-Based Image Enhancement

    Directory of Open Access Journals (Sweden)

    Fabrizio Russo

    2004-09-01

    Full Text Available A novel technique for the sharpening of noisy images is presented. The proposed enhancement system adopts a simple piecewise linear (PWL function in order to sharpen the image edges and to reduce the noise. Such effects can easily be controlled by varying two parameters only. The noise sensitivity of the operator is further decreased by means of an additional filtering step, which resorts to a nonlinear model too. Results of computer simulations show that the proposed sharpening system is simple and effective. The application of the method to contrast enhancement of color images is also discussed.

  18. Limitations of Feedback, Feedforward and IMC Controller for a First Order Non-Linear Process with Dead Time

    Directory of Open Access Journals (Sweden)

    Maruthai Suresh

    2010-10-01

    Full Text Available A nonlinear process, the heat exchanger whose parameters vary with respect to the process variable, is considered. The time constant and gain of the chosen process vary as a function of temperature. The limitations of the conventional feedback controller tuned using Ziegler-Nichols settings for the chosen process are brought out. The servo and regulatory responses through simulation and experimentation for various magnitudes of set-point changes and load changes at various operating points with the controller tuned only at a chosen nominal operating point are obtained and analyzed. Regulatory responses for output load changes are studied. The efficiency of feedforward controller and the effects of modeling error have been brought out. An IMC based system is presented to understand clearly how variations of system parameters affect the performance of the controller. The present work illustrates the effectiveness of Feedforward and IMC controller.

  19. Computing Gröbner Bases within Linear Algebra

    Science.gov (United States)

    Suzuki, Akira

    In this paper, we present an alternative algorithm to compute Gröbner bases, which is based on computations on sparse linear algebra. Both of S-polynomial computations and monomial reductions are computed in linear algebra simultaneously in this algorithm. So it can be implemented to any computational system which can handle linear algebra. For a given ideal in a polynomial ring, it calculates a Gröbner basis along with the corresponding term order appropriately.

  20. Content-Based Object Movie Retrieval and Relevance Feedbacks

    Directory of Open Access Journals (Sweden)

    Lee Greg C

    2007-01-01

    Full Text Available Object movie refers to a set of images captured from different perspectives around a 3D object. Object movie provides a good representation of a physical object because it can provide 3D interactive viewing effect, but does not require 3D model reconstruction. In this paper, we propose an efficient approach for content-based object movie retrieval. In order to retrieve the desired object movie from the database, we first map an object movie into the sampling of a manifold in the feature space. Two different layers of feature descriptors, dense and condensed, are designed to sample the manifold for representing object movies. Based on these descriptors, we define the dissimilarity measure between the query and the target in the object movie database. The query we considered can be either an entire object movie or simply a subset of views. We further design a relevance feedback approach to improving retrieved results. Finally, some experimental results are presented to show the efficacy of our approach.

  1. Grammar Based Genetic Programming Using Linear Representations

    Institute of Scientific and Technical Information of China (English)

    ZHANGHong; LUYinan; WANGFei

    2003-01-01

    In recent years,there has been a great interest in genetic programming(GP),which is used to solve many applications such as data mining,electronic engineering and pattern recognition etc.. Genetic programming paradigm as a from of adaptive learning is a functional approach to many problems that require a nonfixed representation and GP typically operates on a population of parse which usually represent computer programs whose nodes have single data type.In this paper GP using context-free grammars(CFGs) is described.This technique separates search space from solution space through a genotype to phenotype mapping.The genotypes and phenotypes of the individuals both act on different linear representations.A phenotype is postfix expression,a new method of representing which is described by making use of the definition and related features of a context-free grammar,i.e.a genotype is a variable length,linear valid genome determined by a simplifled derivation tree(SDT) generated from a context-free grammar.A CFG is used to specify how the possible solutions are created according to experiential knowledge and to direct legal crossover(ormutation)operations without any explicit reference to the process of program generation and parsing,and automatically ensuring typing and syntax correctness.Some related definitions involving genetic operators are described.Fitness evaluation is given.This technique is applied to a symbol regression problem-the identification of nonlinear dynamic characteristics of cushioning packaging.Experimental results show this method can flnd good relations between variables and is better than basic GP without a grammar.Future research on it is outlined.

  2. Uplink Contention-based CSI Feedback with Prioritized Layers for a Multi-Carrier System

    DEFF Research Database (Denmark)

    Kaneko, Megumi; Hayashi, Kazunori; Popovski, Petar

    2012-01-01

    performance analysis of the proposed scheme, assuming Maximum CSI (Max CSI) and normalized Proportional Fair Scheduler (PFS), where a tight approximation of the achievable throughput is obtained assuming discrete Adaptive Modulation (AM) and CSI feedback which are relevant for the practical systems......, several works have considered contention-based CSI feedback in the UL control channel. We propose such a feedback scheme for a generic MC system, based on the idea of variable collision protection, where the probability that a feedback information experiences a collision depends on its importance...

  3. Peer Feedback to Facilitate Project-Based Learning in an Online Environment

    Science.gov (United States)

    Ching, Yu-Hui; Hsu, Yu-Chang

    2013-01-01

    There has been limited research examining the pedagogical benefits of peer feedback for facilitating project-based learning in an online environment. Using a mixed method approach, this paper examines graduate students' participation and perceptions of peer feedback activity that supports project-based learning in an online instructional design…

  4. The Emergence of Contesting Motives for Student Feedback-Based Evaluation in Australian Higher Education

    Science.gov (United States)

    Darwin, Stephen

    2016-01-01

    Student feedback-based evaluation performs a significant social role in framing perceptions of the quality of teaching in contemporary Australian higher education. Yet its emergence is a relatively recent phenomenon, having only been in widespread application since the mid-1980s. The early manifestations of student feedback-based evaluation came…

  5. LMI-based output feedback fuzzy control of chaotic system with uncertainties

    Institute of Scientific and Technical Information of China (English)

    Tan Wen; Wang Yao-Nan; Duan Feng; Li Xiao-Hui

    2006-01-01

    This paper studies the robust fuzzy control for nonlinear chaotic system in the presence of parametric uncertainties. An uncertain Takagi-Sugeno (T-S) fuzzy model is employed for fuzzy modelling of an unknown chaotic system. A sufficient condition formulated in terms of linear matrix inequality (LMI) for the existence of fuzzy controller is obtained. Then the output feedback fuzzy-model-based regulator derived from the LMI solutions can guarantee the stability of the closed-loop overall fuzzy system. The T-S fuzzy model of the chaotic Chen system is developed as an example for illustration. The effectiveness of the proposed controller design methodology is finally demonstrated through computer simulations on the uncertain Chen chaotic system.

  6. Training based on mirror visual feedback influences transcallosal communication.

    Science.gov (United States)

    Avanzino, Laura; Raffo, Alessia; Pelosin, Elisa; Ogliastro, Carla; Marchese, Roberta; Ruggeri, Piero; Abbruzzese, Giovanni

    2014-08-01

    Mirror visual feedback (MVF) therapy has been demonstrated to be successful in neurorehabilitation, probably inducing neuroplasticity changes in the primary motor cortex (M1). However, it is not known whether MVF training influences the hemispheric balance between the M1s. This topic is of extreme relevance when MVF training is applied to stroke rehabilitation, as the competitive interaction between the two hemispheres induces abnormal interhemispheric inhibition (IHI) that weakens motor function in stroke patients. In the present study, we evaluated, in a group of healthy subjects, the effect of motor training and MVF training on the excitability of the two M1s and the IHI between M1s. The IHI from the 'active' M1 to the opposite M1 (where 'active' means the M1 contralateral to the moving hand in the motor training and the M1 of the seen hand in the MVF training) increased, after training, in both the experimental conditions. Only after motor training did we observe an increase in the excitability of the active M1. Our findings show that training based on MVF may influence the excitability of the transcallosal pathway and support its use in disorders where abnormal IHI is a potential target, such as stroke, where an imbalance between the affected and unaffected M1s has been documented.

  7. Commissioning and Initial Performance of the LHC Beam-Based Feedback Systems

    CERN Document Server

    Boccardi, A; Calvo Giraldo, E; Denz, R; Gasior, M; Gonzalez, JL; Jackson, S; Jensen, LK; Jones, OR; King, Q; Kruk, G; Lamont, M; Page, S; Steinhagen, RJ; Wenninger, J

    2010-01-01

    The LHC deploys a comprehensive suite of beam-based feedbacks for safe and reliable machine operation. This contribution summarises the commissioning and early results of the LHC feedback control systems on orbit, tune, chromaticity, and energy. Their performance – strongly linked to the associated beam instrumentation, external beam perturbation sources and optics uncertainties – is evaluated and compared with the initial feedback design assumptions

  8. FIRM: Sampling-based feedback motion-planning under motion uncertainty and imperfect measurements

    KAUST Repository

    Agha-mohammadi, A.-a.

    2013-11-15

    In this paper we present feedback-based information roadmap (FIRM), a multi-query approach for planning under uncertainty which is a belief-space variant of probabilistic roadmap methods. The crucial feature of FIRM is that the costs associated with the edges are independent of each other, and in this sense it is the first method that generates a graph in belief space that preserves the optimal substructure property. From a practical point of view, FIRM is a robust and reliable planning framework. It is robust since the solution is a feedback and there is no need for expensive replanning. It is reliable because accurate collision probabilities can be computed along the edges. In addition, FIRM is a scalable framework, where the complexity of planning with FIRM is a constant multiplier of the complexity of planning with PRM. In this paper, FIRM is introduced as an abstract framework. As a concrete instantiation of FIRM, we adopt stationary linear quadratic Gaussian (SLQG) controllers as belief stabilizers and introduce the so-called SLQG-FIRM. In SLQG-FIRM we focus on kinematic systems and then extend to dynamical systems by sampling in the equilibrium space. We investigate the performance of SLQG-FIRM in different scenarios. © The Author(s) 2013.

  9. State Feedback H∞ Control of Power Units Based on an Improved Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    Zhongqiang Wu

    2015-01-01

    Full Text Available A new state feedback H∞ control scheme is presented used in the boiler-turbine power units based on an improved particle swarm optimizing algorithm. Firstly, the nonlinear system is transformed into a linear time-varying system; then the H∞ control problem is transformed into the solution of a Riccati equation. The control effect of H∞ controller depends on the selection of matrix P, so an improved particle swarm optimizing (PSO algorithm by introducing differential evolution algorithm is used to solve the Riccati equation. The main purpose is that mutation and crossover are introduced for a new population, and the population diversity is improved. It is beneficial to eliminate stagnation caused by premature convergence, and the algorithm convergence rate is improved. Finally, the real-time optimizing of the controller parameters is realized. Theoretical analysis and simulation results show that a state feedback H∞ controller can be obtained, which can ensure asymptotic stability of the system, and the double objectives of stabilizing system and suppressing the disturbance are got. The system can work well over a large range working point.

  10. A global hybrid coupled model based on atmosphere-SST feedbacks

    Energy Technology Data Exchange (ETDEWEB)

    Cimatoribus, Andrea A.; Drijfhout, Sybren S. [Royal Netherlands Meteorological Institute, De Bilt (Netherlands); Dijkstra, Henk A. [Utrecht University, Institute for Marine and Atmospheric Research Utrecht, Utrecht (Netherlands)

    2012-02-15

    A global hybrid coupled model is developed, with the aim of studying the effects of ocean-atmosphere feedbacks on the stability of the Atlantic meridional overturning circulation. The model includes a global ocean general circulation model and a statistical atmosphere model. The statistical atmosphere model is based on linear regressions of data from a fully coupled climate model on sea surface temperature both locally and hemispherically averaged, being the footprint of Atlantic meridional overturning variability. It provides dynamic boundary conditions to the ocean model for heat, freshwater and wind-stress. A basic but consistent representation of ocean-atmosphere feedbacks is captured in the hybrid coupled model and it is more than 10 times faster than the fully coupled climate model. The hybrid coupled model reaches a steady state with a climate close to the one of the fully coupled climate model, and the two models also have a similar response (collapse) of the Atlantic meridional overturning circulation to a freshwater hosing applied in the northern North Atlantic. (orig.)

  11. Research and development of a stabilizing holographic interference fringe system based on linear CCD

    Science.gov (United States)

    Li, Chaoming; Chen, Xinrong; Wu, Jianhong; Ju, Jianzhi; Zhu, Yayi; Hu, Zuyuan

    2009-07-01

    A method that is to stabilize holographic interference fringe during holographic recording process is put forward in this paper. As the kernel of this method, a negative feedback system based on linear CCD and piezoelectric ceramics (PZT) which is used to compensate the interference fringe random drift caused by various external vibrations in long time recording process was introduced in details. The proportion-integral-derivative method (PID) is adopted to control the moving of PZT which is used to compensate the drift of the interference fringes accurately. Thus the interference fringe can be frozen. Experiment results shows that this negative feedback system by controlling the optical path difference can effectively compensate the interference fringe random drift caused by various external vibrations in long time recording process. After using this system, the mean squared error of the interference fringe drift value can be under λ / 60 and the quality of the holographic grating is improved greatly.

  12. Multi source feedback based performance appraisal system using Fuzzy logic decision support system

    CERN Document Server

    Meenakshi, G

    2012-01-01

    In Multi-Source Feedback or 360 Degree Feedback, data on the performance of an individual are collected systematically from a number of stakeholders and are used for improving performance. The 360-Degree Feedback approach provides a consistent management philosophy meeting the criterion outlined previously. The 360-degree feedback appraisal process describes a human resource methodology that is frequently used for both employee appraisal and employee development. Used in employee performance appraisals, the 360-degree feedback methodology is differentiated from traditional, top-down appraisal methods in which the supervisor responsible for the appraisal provides the majority of the data. Instead it seeks to use information gained from other sources to provide a fuller picture of employees' performances. Similarly, when this technique used in employee development it augments employees' perceptions of training needs with those of the people with whom they interact. The 360-degree feedback based appraisal is a c...

  13. A Biopsychosocial Model Based on Negative Feedback and Control

    Directory of Open Access Journals (Sweden)

    Timothy Andrew Carey

    2014-02-01

    Full Text Available Although the biopsychosocial model has been a popular topic of discussion for over four decades it has not had the traction in fields of research that might be expected of such an intuitively appealing idea. One reason for this might be the absence of an identified mechanism or a functional architecture that is authentically biopsychosocial. What is needed is a robust mechanism that is equally important to biochemical processes as it is to psychological and social processes. Negative feedback may be the mechanism that is required. Negative feedback has been implicated in the regulation of neurotransmitters as well as important psychological and social processes such as emotional regulation and the relationship between a psychotherapist and a client. Moreover, negative feedback is purported to also govern the activity of all other organisms as well as humans. Perceptual Control Theory (PCT describes the way in which negative feedback establishes control at increasing levels of perceptual complexity. Thus, PCT may be the first biopsychosocial model to be articulated in functional terms. In this paper we outline the working model of PCT and explain how PCT provides an embodied hierarchical neural architecture that utilises negative feedback to control physiological, psychological, and social variables. PCT has major implications for both research and practice and, importantly, provides a guide by which fields of research that are currently separated may be integrated to bring about substantial progress in understanding the way in which the brain alters, and is altered by, its behavioural and environmental context.

  14. THE LIMIT CYCLES AND HOPF BIFURCATION OF A CLASS OF SIMPLIFIED HOLLING TYPE-IV PREDATOR-PREY SYSTEM WITH LINEAR STATE FEEDBACK

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this paper, a class of simplified Type-IV predator-prey system with linear state feedback is investigated. We prove the boundedness of the positive solutions to this system, and analyze the quality of the equilibria and the existence of limit cycles of the system surrounding the positive equilibra. By Hopf bifurcation theory, the result of having two limit cycles to the system is obtained.

  15. Factors affecting learning of vector math from computer-based practice: Feedback complexity and prior knowledge

    Science.gov (United States)

    Heckler, Andrew F.; Mikula, Brendon D.

    2016-06-01

    In experiments including over 450 university-level students, we studied the effectiveness and time efficiency of several levels of feedback complexity in simple, computer-based training utilizing static question sequences. The learning domain was simple vector math, an essential skill in introductory physics. In a unique full factorial design, we studied the relative effects of "knowledge of correct response" feedback and "elaborated feedback" (i.e., a general explanation) both separately and together. A number of other factors were analyzed, including training time, physics course grade, prior knowledge of vector math, and student beliefs about both their proficiency in and the importance of vector math. We hypothesize a simple model predicting how the effectiveness of feedback depends on prior knowledge, and the results confirm this knowledge-by-treatment interaction. Most notably, elaborated feedback is the most effective feedback, especially for students with low prior knowledge and low course grade. In contrast, knowledge of correct response feedback was less effective for low-performing students, and including both kinds of feedback did not significantly improve performance compared to elaborated feedback alone. Further, while elaborated feedback resulted in higher scores, the learning rate was at best only marginally higher because the training time was slightly longer. Training time data revealed that students spent significantly more time on the elaborated feedback after answering a training question incorrectly. Finally, we found that training improved student self-reported proficiency and that belief in the importance of the learned domain improved the effectiveness of training. Overall, we found that computer based training with static question sequences and immediate elaborated feedback in the form of simple and general explanations can be an effective way to improve student performance on a physics essential skill, especially for less prepared and low

  16. Designing of vague logic based multilevel feedback queue scheduler

    Directory of Open Access Journals (Sweden)

    Supriya Raheja

    2016-03-01

    Full Text Available Multilevel feedback queue scheduler suffers from major issues of scheduling such as starvation for long tasks, fixed number of queues, and static length of time quantum in each queue. These factors directly affect the performance of the scheduler. At many times impreciseness exists in attributes of tasks which make the performance even worse. In this paper, our intent is to improve the performance by providing a solution to these issues. We design a multilevel feedback queue scheduler using a vague set which we call as VMLFQ scheduler. VMLFQ scheduler intelligently handles the impreciseness and defines the optimum number of queues as well as the optimal size of time quantum for each queue. It also resolves the problem of starvation. This paper simulates and analyzes the performance of VMLFQ scheduler with the other multilevel feedback queue techniques using MatLab.

  17. Simultaneous Computation of Two Independent Tasks Using Reservoir Computing Based on a Single Photonic Nonlinear Node With Optical Feedback.

    Science.gov (United States)

    Nguimdo, Romain Modeste; Verschaffelt, Guy; Danckaert, Jan; Van der Sande, Guy

    2015-12-01

    In this brief, we numerically demonstrate a photonic delay-based reservoir computing system, which processes, in parallel, two independent computational tasks even when the two tasks have unrelated input streams. Our approach is based on a single-longitudinal mode semiconductor ring laser (SRL) with optical feedback. The SRL emits in two directional optical modes. Each directional mode processes one individual task to mitigate possible crosstalk. We illustrate the feasibility of our scheme by analyzing the performance on two benchmark tasks: 1) chaotic time series prediction and 2) nonlinear channel equalization. We identify some feedback configurations for which the results for simultaneous prediction/classification indicate a good performance, but with slight degradation (as compared with the performance obtained for single task processing) due to nonlinear and linear interactions between the two directional modes of the laser. In these configurations, the system performs well on both tasks for a broad range of the parameters.

  18. Value and probability coding in a feedback-based learning task utilizing food rewards

    National Research Council Canada - National Science Library

    Tricomi, Elizabeth; Lempert, Karolina M

    2015-01-01

    .... We investigated the role of the striatum in processing probability-based and value-based negative feedback by training participants to associate cues with food rewards and then employing a selective...

  19. Decoherence control: A feedback mechanism based on hamiltonian tracking

    CERN Document Server

    Katz, G; Kosloff, R; Katz, Gil; Ratner, Mark; Kosloff, Ronnie

    2006-01-01

    Enviroment - caused dissipation disrupts the hamiltonian evolution of all quantum systems not fully isolated from any bath. We propose and examine a feedback-control scheme to eliminate such dissipation, by tracking the free hamiltonian evolution. We determine a driving-field that maximizes the projection of the actual molecular system onto the freely propagated one. The evolution of a model two level system in a dephasing bath is followed, and the driving field that overcomes the decoherence is calculated. An implementation of the scheme in the laboratory using feedback control is suggested.

  20. High Accuracy Passive Magnetic Field-Based Localization for Feedback Control Using Principal Component Analysis

    Directory of Open Access Journals (Sweden)

    Shaohui Foong

    2016-08-01

    Full Text Available In this paper, a novel magnetic field-based sensing system employing statistically optimized concurrent multiple sensor outputs for precise field-position association and localization is presented. This method capitalizes on the independence between simultaneous spatial field measurements at multiple locations to induce unique correspondences between field and position. This single-source-multi-sensor configuration is able to achieve accurate and precise localization and tracking of translational motion without contact over large travel distances for feedback control. Principal component analysis (PCA is used as a pseudo-linear filter to optimally reduce the dimensions of the multi-sensor output space for computationally efficient field-position mapping with artificial neural networks (ANNs. Numerical simulations are employed to investigate the effects of geometric parameters and Gaussian noise corruption on PCA assisted ANN mapping performance. Using a 9-sensor network, the sensing accuracy and closed-loop tracking performance of the proposed optimal field-based sensing system is experimentally evaluated on a linear actuator with a significantly more expensive optical encoder as a comparison.

  1. High Accuracy Passive Magnetic Field-Based Localization for Feedback Control Using Principal Component Analysis

    Science.gov (United States)

    Foong, Shaohui; Sun, Zhenglong

    2016-01-01

    In this paper, a novel magnetic field-based sensing system employing statistically optimized concurrent multiple sensor outputs for precise field-position association and localization is presented. This method capitalizes on the independence between simultaneous spatial field measurements at multiple locations to induce unique correspondences between field and position. This single-source-multi-sensor configuration is able to achieve accurate and precise localization and tracking of translational motion without contact over large travel distances for feedback control. Principal component analysis (PCA) is used as a pseudo-linear filter to optimally reduce the dimensions of the multi-sensor output space for computationally efficient field-position mapping with artificial neural networks (ANNs). Numerical simulations are employed to investigate the effects of geometric parameters and Gaussian noise corruption on PCA assisted ANN mapping performance. Using a 9-sensor network, the sensing accuracy and closed-loop tracking performance of the proposed optimal field-based sensing system is experimentally evaluated on a linear actuator with a significantly more expensive optical encoder as a comparison. PMID:27529253

  2. High Accuracy Passive Magnetic Field-Based Localization for Feedback Control Using Principal Component Analysis.

    Science.gov (United States)

    Foong, Shaohui; Sun, Zhenglong

    2016-08-12

    In this paper, a novel magnetic field-based sensing system employing statistically optimized concurrent multiple sensor outputs for precise field-position association and localization is presented. This method capitalizes on the independence between simultaneous spatial field measurements at multiple locations to induce unique correspondences between field and position. This single-source-multi-sensor configuration is able to achieve accurate and precise localization and tracking of translational motion without contact over large travel distances for feedback control. Principal component analysis (PCA) is used as a pseudo-linear filter to optimally reduce the dimensions of the multi-sensor output space for computationally efficient field-position mapping with artificial neural networks (ANNs). Numerical simulations are employed to investigate the effects of geometric parameters and Gaussian noise corruption on PCA assisted ANN mapping performance. Using a 9-sensor network, the sensing accuracy and closed-loop tracking performance of the proposed optimal field-based sensing system is experimentally evaluated on a linear actuator with a significantly more expensive optical encoder as a comparison.

  3. Accelerometer Based Motional Feedback Integrated in a 2 3/4" Loudspeaker

    DEFF Research Database (Denmark)

    Bjerregaard, Ruben; Madsen, Anders Normann; Schneider, Henrik;

    2016-01-01

    described in the 1960s showing good results at low frequencies. In spite of this, the technique has mainly been used for closed box subwoofers to a limited extent. In this paper, design and experimental results for a 23/4" acceleration based motional feedback loudspeaker are shown to extend this feedback...

  4. 永磁同步风电系统建模及直接反馈线性化控制%Modeling and Direct Feedback Linearization Control for PMSG Wind Power Generation System

    Institute of Scientific and Technical Information of China (English)

    王武

    2015-01-01

    构建了空气动力学系统、永磁同步发电机子系统和反馈线性化控制子系统的模型,并给出了具体的MATLAB仿真模型。给出了直接反馈线性化控制的基本原理和实现方法,将该控制策略应用到永磁同步风力发电系统中,采用微分几何线性化理论和最大风能捕获原理,实现了坐标变换和非线性系统状态反馈,达到了永磁同步风电系统线性化,并在MATLAB环境下给出了具体的仿真框图和实现技术。通过系统联合仿真,表明所建永磁同步发电系统模型可以有效实现对控制系统性能的测试,反馈线性化控制具有更高的控制性能,能够确保最大风能捕获。通过研究,找到永磁同步风电系统这一非线性系统的线性化控制策略,从而提升系统的控制品质。%The PMSG wind power system was constructed with mathematical models of aerodynamics subsystem, feedback linearization control subsystem and PMSG subsystem, also the MATALB simulation model was proposed. The theory of direct feedback linearization control was proposed and applied into the model constructed. The nonlinear model realized with feedback linearization control based on differential geometry, the coordinated transformation and nonlinear state feedback were obtained and PMSG wind power system was constructed under MATLAB, the simulation parameters was designed and the simulation result shows the control model was stable and direct feedback linearization control with higher tracking performance, which can effectively implement maximum energy capture. With the research work,the linearization method for PMSG wind power system can be proposed and the control ability enhanced.

  5. A Neurophysiological examination of quality of learning in a feedback-based learning task.

    Science.gov (United States)

    Arbel, Yael; Wu, Hao

    2016-12-01

    The efficiency with which one processes external feedback contributes to the speed and quality of one's learning. Previous findings that the feedback related negativity (FRN) event related potential (ERP) is modulated by learning outcomes suggested that this ERP reflects the extent to which feedback is used by the learner to improve performance. To further test this suggestion, we measured whether the FRN and the fronto-central positivity (FCP) that follows it are modulated by learning slopes, and as a function of individual differences in learning outcomes. Participants were tasked with learning names (non-words) of 42 novel objects in a two-choice feedback-based visual learning task. The items were divided into three sets of 14 items, each presented in five learning blocks and a sixth test block. Individual learning slopes based on performance on the task, as well as FRN and FCP slopes based on positive and negative feedback related activation in each block were created for 53 participants. Our data pointed to an interaction between slopes of the FRN elicited by negative feedback and learning slopes, such that a sharper decrease in the amplitude of the FRN to negative feedback was associated with sharper learning slopes. We further examined the predictive power of the FRN and FCP elicited in the training blocks on the learning outcomes as measured by performance on the test blocks. We found that small FRN to negative feedback, large FRN to positive feedback, and large FCP to negative feedback in the first training block predicted better learning outcomes. These results add to the growing evidence that the processes giving rise to the FRN and FCP are sensitive to individual differences in the extent to which feedback is used for learning. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Flatness-based active disturbance rejection control for linear systems with unknown time-varying coefficients

    Science.gov (United States)

    Huang, Congzhi; Sira-Ramírez, Hebertt

    2015-12-01

    A flatness-based active disturbance rejection control approach is proposed to deal with the linear systems with unknown time-varying coefficients and external disturbances. By selecting appropriate nominal values for the parameters of the system, all the deviation between the nominal and actual dynamics of the controlled process, as well as all the external disturbances can be viewed as a total disturbance. Based on the accurately estimated total disturbance with the aid of the proposed extended state observer, a linear proportional derivative feedback control law taking into account the derivatives of the desired output is designed to eliminate the effect of the total disturbance on the system performance. Finally, the load frequency control problem of a single-area power system with non-reheated unit is employed as an illustrative example to demonstrate the effectiveness of the proposed approach.

  7. Multiple Description Coding with Feedback Based Network Compression

    DEFF Research Database (Denmark)

    Sørensen, Jesper Hemming; Østergaard, Jan; Popovski, Petar

    2010-01-01

    and an intermediate node, respectively. A trade-off exists between reducing the delay of the feedback by adapting in the vicinity of the receiver and increasing the gain from compression by adapting close to the source. The analysis shows that adaptation in the network provides a better trade-off than adaptation...

  8. Passive output feedback and observer based autopilots: A comparative study

    Directory of Open Access Journals (Sweden)

    Marit Paulsen

    1996-04-01

    Full Text Available Two methods for course-keeping of a ship are studied where no measurements of the yaw rate are available. The two methods are a passive output feedback controller and a controller-observer structure. A comparison with special attention to stability and wave filtering properties, is provided. Finally, a case study of a ship autopilot is included.

  9. Mining Distance-Based Outliers in Near Linear Time

    Data.gov (United States)

    National Aeronautics and Space Administration — Full title: Mining Distance-Based Outliers in Near Linear Time with Randomization and a Simple Pruning Rule Abstract: Defining outliers by their distance to...

  10. 3D Object Recognition Based on Linear Lie Algebra Model

    Institute of Scientific and Technical Information of China (English)

    LI Fang-xing; WU Ping-dong; SUN Hua-fei; PENG Lin-yu

    2009-01-01

    A surface model called the fibre bundle model and a 3D object model based on linear Lie algebra model are proposed.Then an algorithm of 3D object recognition using the linear Lie algebra models is presented.It is a convenient recognition method for the objects which are symmetric about some axis.By using the presented algorithm,the representation matrices of the fibre or the base curve from only finite points of the linear Lie algebra model can be obtained.At last some recognition results of practicalities are given.

  11. Comparison of linear and non-linear monotonicity-based shape reconstruction using exact matrix characterizations

    DEFF Research Database (Denmark)

    Garde, Henrik

    2017-01-01

    Detecting inhomogeneities in the electrical conductivity is a special case of the inverse problem in electrical impedance tomography, that leads to fast direct reconstruction methods. One such method can, under reasonable assumptions, exactly characterize the inhomogeneities based on monotonicity....... For a fair comparison, exact matrix characterizations are used when probing the monotonicity relations to avoid errors from numerical solution to PDEs and numerical integration. Using a special factorization of the Neumann-to-Dirichlet map also makes the non-linear method as fast as the linear method...

  12. Multi source feedback based performance appraisal system using Fuzzy logic decision support system

    Directory of Open Access Journals (Sweden)

    G.Meenakshi

    2012-03-01

    Full Text Available In Multi-Source Feedback or 360 Degree Feedback, data on the performance of an individual are collected systematically from a number of stakeholders and are used for improving performance. The 360-Degree Feedback approach provides a consistent management philosophy meeting the criterion outlined previously. The 360-degree feedback appraisal process describes a human resource methodology that is frequently used for both employee appraisal and employee development. Used in employee performance appraisals, the 360-degree feedback methodology is differentiated from traditional, top-down appraisalmethods in which the supervisor responsible for the appraisal provides the majority of the data. Instead it seeks to use information gained from other sources to provide a fuller picture of employees’ performances. Similarly, when this technique used in employee development it augments employees’ perceptions of training needs with those of the people with whom they interact. The 360-degree feedback based appraisal is a comprehensive method where in the feedback about the employee comes from all the sources that come into contact with the employee on his/her job. The respondents for an employee can be her/his peers, managers, subordinates team members, customers, suppliers and vendors. Hence anyone who comes into contact with the employee, the 360 degree appraisal has four components that include self-appraisal, superior’s appraisal, subordinate’s appraisal student’s appraisal and peer’s appraisal .The proposed system is an attempt to implement the 360 degree feedback based appraisal system in academics especially engineering colleges.

  13. A Novel Method of Robust Trajectory Linearization Control Based on Disturbance Rejection

    Directory of Open Access Journals (Sweden)

    Xingling Shao

    2014-01-01

    Full Text Available A novel method of robust trajectory linearization control for a class of nonlinear systems with uncertainties based on disturbance rejection is proposed. Firstly, on the basis of trajectory linearization control (TLC method, a feedback linearization based control law is designed to transform the original tracking error dynamics to the canonical integral-chain form. To address the issue of reducing the influence made by uncertainties, with tracking error as input, linear extended state observer (LESO is constructed to estimate the tracking error vector, as well as the uncertainties in an integrated manner. Meanwhile, the boundedness of the estimated error is investigated by theoretical analysis. In addition, decoupled controller (which has the characteristic of well-tuning and simple form based on LESO is synthesized to realize the output tracking for closed-loop system. The closed-loop stability of the system under the proposed LESO-based control structure is established. Also, simulation results are presented to illustrate the effectiveness of the control strategy.

  14. A DSP-based controller for a linear actuator system with sub-angstrom resolution and 15-millimeter travel range

    Energy Technology Data Exchange (ETDEWEB)

    Smolyanitskiy, A.; Shu, D.; Wong, T.; Experimental Facilities Division (APS); IIT

    2005-01-01

    We have designed and tested a new digital signal processor (DSP)-based closed-loop feedback controller for a linear actuator system with sub-angstrom resolution and 15-mm travel range. The linear actuator system consists of a laser Doppler encoder with multiple-reflection optics [1], a high-stiffness weak-link mechanism with high driving sensitivity and stability [2], and a Texas Instruments TMS320C40 DSP-based controller for high-performance closed-loop feedback control. In this paper, we discuss the DSP-based controller design, as well as recent test results yielding step sizes below 50 picometers obtained with the atomic force microprobe setup.

  15. A linear coherent integrated receiver based on a broadband optical phase-locked loop

    Science.gov (United States)

    Ramaswamy, Anand

    Optical Phase-Locked Loops (OPLL) have diverse applications in future communication systems. They can be used in high sensitivity homodyne phase-shift keying receivers for phase noise reduction, provided sufficient loop bandwidth is maintained. Alternative phase-locked loop applications include coherent synchronization of laser arrays and frequency synthesis by offset locking. In this work, a broadband OPLL based coherent receiver is used for linear phase demodulation. Phase modulated (PM) analog optical links have the potential to outperform conventional direct detection links. However, their progress has been stymied by the lack of a linear phase demodulator. We describe how feedback can be used to suppress non-linearities arising from the phase demodulation process. The receiver concept is demonstrated at low frequencies and is found to improve the Spurious Free Dynamic Range (SFDR) of an experimental analog link by over 20dB. In order to extend the operation of the receiver to microwave frequencies, latencies arising from physical delays in the feedback path need to be dramatically reduced. To facilitate this, monolithic and hybrid versions of the receiver based on compact integration of InP photonic integrated circuits (PIC) with InP and SiGe electronic integrated circuits (EIC) have been developed at UCSB. In this work, we develop novel measurement techniques to characterize the linearity of the individual components of the PIC, namely, the semiconductor photodiodes and optical phase modulators. We then demonstrate the operation of the receiver in a high power analog link. The OPLL based receiver has a bandwidth of 1.5GHz. The link gain and shot-noise limited SFDR at 300MHz are -2dB and 125dB-Hz2/3, respectively. Further, optical sampling downconversion is demonstrated as a viable technique to increase the operating frequency of the receiver beyond the baseband range.

  16. Adaptive Multi-Objective Optimization Based on Feedback Design

    Institute of Scientific and Technical Information of China (English)

    窦立谦; 宗群; 吉月辉; 曾凡琳

    2010-01-01

    The problem of adaptive multi-objective optimization(AMOO) has received extensive attention due to its practical significance.An important issue in optimizing a multi-objective system is adjusting the weighting coefficients of multiple objectives so as to keep track of various conditions.In this paper,a feedback structure for AMOO is designed.Moreover,the reinforcement learning combined with hidden biasing information is applied to online tuning weighting coefficients of objective functions.Finally,the prop...

  17. Plenoptic microscope based on laser optical feedback imaging (LOFI)

    CERN Document Server

    Glastre, W; Jacquin, O; de Chatellus, H Guillet; Lacot, E

    2015-01-01

    We present an overview of the performances of a plenoptic microscope which combines the high sensitivity of a laser optical feedback imaging setup , the high resolution of optical synthetic aperture and a shot noise limited signal to noise ratio by using acoustic photon tagging. By using an adapted phase filtering, this microscope allows phase drift correction and numerical aberration compensation (defocusing, coma, astigmatism ...). This new kind of microscope seems to be well adapted to make deep imaging through scattering and heterogeneous media.

  18. Influence of the absorber dimensions on wavefront shaping based on volumetric optoacoustic feedback

    CERN Document Server

    Dean-Ben, X L; Ozbek, A; Razansky, D

    2015-01-01

    The recently demonstrated control over light distribution through turbid media based on real-time three-dimensional optoacoustic feedback has offered promising prospects to interferometrically focus light within scattering objects. Nevertheless, the focusing capacity of the feedback-based approach is strongly conditioned by the number of effectively resolvable optical modes (speckles). In this letter, we experimentally tested the light intensity enhancement achieved with optoacoustic feedback measurements from different sizes of absorbing microparticles. The importance of the obtained results is discussed in the context of potential signal enhancement at deep locations within a scattering medium where the effective speckle sizes approach the minimum values dictated by optical diffraction.

  19. WEB-BASED DATA MINING TOOLS : PERFORMING FEEDBACK ANALYSIS AND ASSOCIATION RULE MINING

    Directory of Open Access Journals (Sweden)

    Pratiyush Guleria

    2015-11-01

    Full Text Available This paper aims to explain the web-enabled tools for educational data mining. The proposed web-based tool developed using Asp.Net framework and php can be helpful for universities or institutions providing the students with elective courses as well improving academic activities based on feedback collected from students. In Asp.Net tool, association rule mining using Apriori algorithm is used whereas in php based Feedback Analytical Tool, feedback related to faculty and institutional infrastructure is collected from students and based on that Feedback it shows performance of faculty and institution. Using that data, it helps management to improve in-house training skills and gains knowledge about educational trends which is to be followed by faculty to improve the effectiveness of the course and teaching skills.

  20. Experimental Model Based Feedback Control for Flutter Suppression and Gust Load Alleviation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ZONA Technology, Inc. (ZONA) proposes an R&D effort to develop an Experimental Model Based Feedback Control (EMBFC) Framework for the flutter suppression and...

  1. Tunable Erbium-Doped Fiber Laser Based on Random Distributed Feedback

    National Research Council Canada - National Science Library

    Lulu Wang; Xinyong Dong; Shum, Perry Ping; Haibin Su

    2014-01-01

    A tunable erbium-doped fiber (EDF) laser based on random distributed feedback through backward Rayleigh scattering in a 20-km-long single-mode fiber and a tunable fiber Fabry-Perot interferometer filter is demonstrated...

  2. Virtual estimator for piecewise linear systems based on observability analysis.

    Science.gov (United States)

    Morales-Morales, Cornelio; Adam-Medina, Manuel; Cervantes, Ilse; Vela-Valdés, Luis G; Beltrán, Carlos Daniel García

    2013-02-27

    This article proposes a virtual sensor for piecewise linear systems based on observability analysis that is in function of a commutation law related with the system's outpu. This virtual sensor is also known as a state estimator. Besides, it presents a detector of active mode when the commutation sequences of each linear subsystem are arbitrary and unknown. For the previous, this article proposes a set of virtual estimators that discern the commutation paths of the system and allow estimating their output. In this work a methodology in order to test the observability for piecewise linear systems with discrete time is proposed. An academic example is presented to show the obtained results.

  3. Virtual Estimator for Piecewise Linear Systems Based on Observability Analysis

    Science.gov (United States)

    Morales-Morales, Cornelio; Adam-Medina, Manuel; Cervantes, Ilse; Vela-Valdés and, Luis G.; García Beltrán, Carlos Daniel

    2013-01-01

    This article proposes a virtual sensor for piecewise linear systems based on observability analysis that is in function of a commutation law related with the system's outpu. This virtual sensor is also known as a state estimator. Besides, it presents a detector of active mode when the commutation sequences of each linear subsystem are arbitrary and unknown. For the previous, this article proposes a set of virtual estimators that discern the commutation paths of the system and allow estimating their output. In this work a methodology in order to test the observability for piecewise linear systems with discrete time is proposed. An academic example is presented to show the obtained results. PMID:23447007

  4. Optical feedback-induced light modulation for fiber-based laser ablation.

    Science.gov (United States)

    Kang, Hyun Wook

    2014-11-01

    Optical fibers have been used as a minimally invasive tool in various medical fields. However, due to excessive heat accumulation, the distal end of a fiber often suffers from severe melting or devitrification, leading to the eventual fiber failure during laser treatment. In order to minimize thermal damage at the fiber tip, an optical feedback sensor was developed and tested ex vivo. Porcine kidney tissue was used to evaluate the feasibility of optical feedback in terms of signal activation, ablation performance, and light transmission. Testing various signal thresholds demonstrated that 3 V was relatively appropriate to trigger the feedback sensor and to prevent the fiber deterioration during kidney tissue ablation. Based upon the development of temporal signal signatures, full contact mode rapidly activated the optical feedback sensor possibly due to heat accumulation. Modulated light delivery induced by optical feedback diminished ablation efficiency by 30% in comparison with no feedback case. However, long-term transmission results validated that laser ablation assisted with optical feedback was able to almost consistently sustain light delivery to the tissue as well as ablation efficiency. Therefore, an optical feedback sensor can be a feasible tool to protect optical fiber tips by minimizing debris contamination and delaying thermal damage process and to ensure more efficient and safer laser-induced tissue ablation.

  5. Observer-based passive control for uncertain linear systems with delay in state and control input

    Institute of Scientific and Technical Information of China (English)

    Li Gui-Fang; Li Hui-Ying; Yang Cheng-Wu

    2005-01-01

    This paper deals with the robust passivity synthesis problem for a class of uncertain linear systems with timevarying delay in state and control input. The parameter uncertainties are norm-bounded and allowed to appear in all matrices of the model. The problem aims at designing an observer-based dynamic output-feedback controller that robustly stabilizes the uncertain systems and achieves the strict passivity of closed-loop systems for all admissible uncertainties. By converting the problem at hand into a class of strictly passive control problem for a parameterized system, the explicit solution is established and expressed in terms of a linear matrix inequality. A numerical example is provided to demonstrate the validity of the proposed approach.

  6. Navigating User Feedback Channels to Chart an Evidence Based Course for Library Redesign

    Directory of Open Access Journals (Sweden)

    T. Derek Halling

    2012-03-01

    Full Text Available Objectives – The objective of this project was to redesign library spaces based on the user feedback obtained from a broad complement of feedback channels. The over-arching goal of this project was to develop an evidence based approach to the redesign of library spaces.Methods – Data from user-initiated and library-initiated feedback channels were collected and analyzed to determine priorities for library space changes. Online/onsite suggestions, a library onsite census survey, the LibQUAL+® survey, a whiteboard, ballot voting, and text voting were all used to gather input. A student advisory group was used as a sounding board for planned space changes before a final decision was made.Results – Data produced by different feedback channels varied both in the number of suggestions generated as well as the changes requested. Composite data from all feedback channels resulted in a total of 687 suggestions identifying 17 different types of space changes. An onsite whiteboard, the LibQUAL+® survey, and library census proved the most prolific in producing suggestions.Conclusion – Priorities for space changes were best determined through a composite of suggestions received from all feedback channels. The number of suggestions and requests received that were initiated by users was so small that it had to be supplemented with library-initiated feedback requests. The use of multiple feedback channels enhanced the number, variety, and scope of the suggestions that were received. Similar requests received through multiple feedback channels emphasized their importance to users. Focused follow-up feedback channels were effective in clarifying user suggestions for specific changes.

  7. Resource-oriented Programming Based on Linear Logic

    Directory of Open Access Journals (Sweden)

    Valerie Novitzká

    2007-08-01

    Full Text Available In our research we consider programming as logical reasoning over types.Linear logic with its resource-oriented features yields a proper means for our approachbecause it enables to consider about resources as in real life: after their use they areexhausted. Computation then can be regarded as proof search. In our paper we presenthow space and time can be introduced into this logic and we discuss several programminglanguages based on linear logic.

  8. Commutator-based linearization of $N = 1$ nonlinear supersymmetry

    CERN Document Server

    Tsuda, Motomu

    2016-01-01

    We consider the linearization of $N = 1$ nonlinear supersymmetry (NLSUSY) based on a commutator algebra in Volkov-Akulov NLSUSY theory. We show explicitly that $U(1)$ gauge and scalar supermultiplets in addition to a vector supermultiplet with general auxiliary fields in linear SUSY theories are obtained from a same set of bosonic and fermionic functionals (composites) which are expressed as simple products of the powers of a Nambu-Goldstone fermion and a fundamental determinant in the NLSUSY theory.

  9. The role of feedback in improving the effectiveness of workplace based assessments: a systematic review

    Directory of Open Access Journals (Sweden)

    Saedon Habiba

    2012-05-01

    Full Text Available Abstract Background With recent emphasis placed on workplace based assessment (WBA as a method of formative performance assessment, there is limited evidence in the current literature regarding the role of feedback in improving the effectiveness of WBA. The aim of this systematic review was to elucidate the impact of feedback on the effectiveness of WBA in postgraduate medical training. Methods Searches were conducted using the following bibliographic databases to identify original published studies related to WBA and the role of feedback: Medline (1950-December 2010, Embase (1980-December 2010 and Journals@Ovid (English language only, 1996-December 2010. Studies which attempted to evaluate the role of feedback in WBA involving postgraduate doctors were included. Results 15 identified studies met the inclusion criteria and minimum quality threshold. They were heterogeneous in methodological design. 7 studies focused on multi source feedback, 3 studies were based on mini-clinical evaluation exercise, 2 looked at procedural based assessment, one study looked at workplace based assessments in general and 2 studies looked at a combination of 3 to 6 workplace based assessments. 7 studies originated from the United Kingdom. Others were from Canada, the United States and New Zealand. Study populations were doctors in various grades of training from a wide range of specialties including general practice, general medicine, general surgery, dermatology, paediatrics and anaesthetics. All studies were prospective in design, and non-comparative descriptive or observational studies using a variety of methods including questionnaires, one to one interviews and focus groups. Conclusions The evidence base contains few high quality conclusive studies and more studies are required to provide further evidence for the effect of feedback from workplace based assessment on subsequent performance. There is, however, good evidence that if well implemented, feedback from

  10. Implementation of neural network based non-linear predictive

    DEFF Research Database (Denmark)

    Sørensen, Paul Haase; Nørgård, Peter Magnus; Ravn, Ole

    1998-01-01

    -linear systems. GPC is model-based and in this paper we propose the use of a neural network for the modeling of the system. Based on the neural network model a controller with extended control horizon is developed and the implementation issues are discussed, with particular emphasis on an efficient Quasi...

  11. Implementation of neural network based non-linear predictive control

    DEFF Research Database (Denmark)

    Sørensen, Paul Haase; Nørgård, Peter Magnus; Ravn, Ole

    1999-01-01

    of non-linear systems. GPC is model based and in this paper we propose the use of a neural network for the modeling of the system. Based on the neural network model, a controller with extended control horizon is developed and the implementation issues are discussed, with particular emphasis...

  12. A family of quantization based piecewise linear filter networks

    DEFF Research Database (Denmark)

    Sørensen, John Aasted

    1992-01-01

    A family of quantization-based piecewise linear filter networks is proposed. For stationary signals, a filter network from this family is a generalization of the classical Wiener filter with an input signal and a desired response. The construction of the filter network is based on quantization of...

  13. Resistive Wall Mode feedback on DIII-D using Linear Quadratic Gaussian control and a GPU powered control system

    Science.gov (United States)

    Clement, M. D.; Navratil, G. A.; Hanson, J. M.; Bialek, J.; Piglowski, D. A.; Penaflor, B. G.

    2015-11-01

    A Graphics Processing Unit (GPU) based control system has been installed on the DIII-D tokamak for Resistive Wall Mode (RWM) control similar to one implemented at the HBT-EP tokamak. DIII-D can excite RWMs, which are strong, locked or nearly locked kink modes whose rotation frequencies do not evolve quickly and are slow compared to their growth rates. Simulations have predicted that modern control techniques like Linear Quadratic Gaussian (LQG) control will perform better than classical control techniques when using control coils external to the vacuum vessel. An LQG control algorithm based on the VALEN model for the RWM has been developed and tested on this system. Early tests have shown the algorithm is able to track and suppress with external control coils the plasma response of an n=1 perturbation driven by internal control coils. An overview of the control hardware, VALEN model, control algorithm and initial results will be presented. Supported by the US DOE under DE-FG02-04ER54761 and DE-FC02-04ER54698.

  14. 具有反馈控制的非自治Logistic模型的正周期解%Positive Periodic Solution for a Nonautonomous Logistic Model with Linear Feedback Regulation

    Institute of Scientific and Technical Information of China (English)

    丁孝全; 程述汉

    2006-01-01

    A nonautonomous delayed logistic model with linear feedback regulation is proposed in this paper. Sufficient conditions are derived for the existence, uniqueness and global asymptotic stability of positive periodic solution of the model.

  15. Feedback-based Intra Refresh Scheme for Wireless Video Transmission

    Institute of Scientific and Technical Information of China (English)

    FENGXiubo; XIEJianying

    2004-01-01

    This paper investigates the intra refresh techniques for video transmission in wireless scenario. Twostate Markov model is proposed to simulate the fading wireless channel. Taking feedback information into account, we analyze the channel distortion due to the burst errors. An improved intra refresh scheme is then proposed for optimal selection of coding mode for each Macroblock (MB) in rate-distortion framework. The propo sedscheme can stop error propagation and reduce channel distortion effectively. Simulations using TMN10 show that our scheme obtains improved performance with respect to error resilience for wireless video communication.

  16. Linear irreversible heat engines based on local equilibrium assumptions

    Science.gov (United States)

    Izumida, Yuki; Okuda, Koji

    2015-08-01

    We formulate an endoreversible finite-time Carnot cycle model based on the assumptions of local equilibrium and constant energy flux, where the efficiency and the power are expressed in terms of the thermodynamic variables of the working substance. By analyzing the entropy production rate caused by the heat transfer in each isothermal process during the cycle, and using the endoreversible condition applied to the linear response regime, we identify the thermodynamic flux and force of the present system and obtain a linear relation that connects them. We calculate the efficiency at maximum power in the linear response regime by using the linear relation, which agrees with the Curzon-Ahlborn (CA) efficiency known as the upper bound in this regime. This reason is also elucidated by rewriting our model into the form of the Onsager relations, where our model turns out to satisfy the tight-coupling condition leading to the CA efficiency.

  17. Change-Of-Bases Abstractions for Non-Linear Systems

    CERN Document Server

    Sankaranarayanan, Sriram

    2012-01-01

    We present abstraction techniques that transform a given non-linear dynamical system into a linear system or an algebraic system described by polynomials of bounded degree, such that, invariant properties of the resulting abstraction can be used to infer invariants for the original system. The abstraction techniques rely on a change-of-basis transformation that associates each state variable of the abstract system with a function involving the state variables of the original system. We present conditions under which a given change of basis transformation for a non-linear system can define an abstraction. Furthermore, the techniques developed here apply to continuous systems defined by Ordinary Differential Equations (ODEs), discrete systems defined by transition systems and hybrid systems that combine continuous as well as discrete subsystems. The techniques presented here allow us to discover, given a non-linear system, if a change of bases transformation involving degree-bounded polynomials yielding an alge...

  18. Negative feedback regulation is responsible for the non-linear modulation of photosynthetic activity in plants and cyanobacteria exposed to a dynamic light environment.

    Science.gov (United States)

    Nedbal, Ladislav; Brezina, Vítezslav; Adamec, Frantisek; Stys, Dalibor; Oja, Vello; Laisk, Agu; Govindjee

    2003-10-17

    Photosynthetic organisms exposed to a dynamic light environment exhibit complex transients of photosynthetic activities that are strongly dependent on the temporal pattern of the incident irradiance. In a harmonically modulated light of intensity I approximately const.+sin(omegat), chlorophyll fluorescence response consists of a steady-state component, a component modulated with the angular frequency of the irradiance omega and several upper harmonic components (2omega, 3omega and higher). Our earlier reverse engineering analysis suggests that the non-linear response can be caused by a negative feedback regulation of photosynthesis. Here, we present experimental evidence that the negative feedback regulation of the energetic coupling between phycobilisome and Photosystem II (PSII) in the cyanobacterium Synechocystis sp. PCC6803 indeed results in the appearance of upper harmonic modes in the chlorophyll fluorescence emission. Dynamic changes in the coupling of the phycobilisome to PSII are not accompanied by corresponding antiparallel changes in the Photosystem I (PSI) excitation, suggesting a regulation limited to PSII. Strong upper harmonic modes were also found in the kinetics of the non-photochemical quenching (NPQ) of chlorophyll fluorescence, of the P700 redox state and of the CO(2) assimilation in tobacco (Nicotiana tabaccum) exposed to harmonically modulated light. They are ascribed to negative feedback regulation of the reactions of the Calvin-Benson cycle limiting the photosynthetic electron transport. We propose that the observed non-linear response of photosynthesis may also be relevant in a natural light environment that is modulated, e.g., by ocean waves, moving canopy or by varying cloud cover. Under controlled laboratory conditions, the non-linear photosynthetic response provides a new insight into dynamics of the regulatory processes.

  19. Synchronization control of cross-strict feedback hyperchaotic system based on cross active backstepping design

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jing [School of Electrical Engineering, Xi' an Jiaotong University, Xi' an 710049 (China)], E-mail: wjnotice@gmail.com; Gao Jinfeng [School of Electrical Engineering, Zhengzhou University, Zhengzhou 450002 (China); Ma Xikui [School of Electrical Engineering, Xi' an Jiaotong University, Xi' an 710049 (China)

    2007-10-01

    This Letter presents a novel cross active backstepping design method for synchronization control of cross-strict feedback hyperchaotic system, in which the ordinary backstepping design is unavailable. The proposed control method, combining backstepping design and active control approach, extends the application of backstepping technique in chaos control. Based on this method, different combinations of controllers can be designed to meet the needs of different applications. The proposed method is applied to achieve chaos synchronization of two identical cross-strict feedback hyperchaotic systems. Also it is used to implement synchronization between cross-strict feedback hyperchaotic system and Roessler hyperchaotic system. Numerical examples illustrate the validity of the control method.

  20. Non-linear quenching of current fluctuations in a self-exciting homopolar dynamo, proved by feedback system theory

    Science.gov (United States)

    de Paor, A. M.

    Hide (Nonlinear Processes in Geophysics, 1998) has produced a new mathematical model of a self-exciting homopolar dynamo driving a series- wound motor, as a continuing contribution to the theory of the geomagnetic field. By a process of exact perturbation analysis, followed by combination and partial solution of differential equations, the complete nonlinear quenching of current fluctuations reported by Hide in the case that a parameter ɛ has the value 1 is proved via the Popov theorem from feedback system stability theory.

  1. Phase detector and phase feedback for a single bunch in a two-bunch damping ring for the SLAC Linear Collider

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, H.D.; Judkins, J.G.

    1987-03-01

    The synchronous phase of a bunch of positrons or electrons being damped in a SLAC Linear Collider (SLC) damping ring is dependent on beam intensity. Injection for alternate bunches into the SLC linac from the damping rings should occur at a constant phase. A phase detector was developed allowing the measurement of phase of a single-stored bunch in the presence of a second bunch in reference to the phase of the linac. The single-bunch phase is derived from beam position monitor signals using a switching scheme to separate the two bunches circulating in each damping ring. The hardware is described including feedback loops to stabilize the extraction phase.

  2. Comparison Between id =0 Vector Controller and Feedback Linearization Controller%反馈线性化控制器与id=0矢量控制器的比较

    Institute of Scientific and Technical Information of China (English)

    宋晓晶

    2013-01-01

    In recent years,new control theory of AC theory and research with the rapid development of power electronics, motor manufacturing technology continued to deepen,and control system of permanent magnet synchronous motors (PMSM) were widely used in high precision and high reliability. This paper based on feedback linearization control and id=0 vector control theory designed two separate types of controllers,and model,and simulation comparison: When the system parameters constant feedback linearization controller fast response time,small overshoot and disturbance was strong,steady state error was smaller. When the system parameter uncertainty about,once load mutation, feedback linearization controller parameters to the dependence and the sensitivity of the changes were enhanced.%近年来,交流调速理论和新型控制理论的研究工作随着电力电子、电机制造业技术迅猛发展而不断深入,永磁同步电动机控制系统广泛应用在要求高控制精度和高可靠性的场合.文中基于id=0矢量控制与反馈线性化控制的理论分别设计两种控制器,并对其模型进行仿真比较得到:当系统参数不变时反馈线性化控制器的响应时间快,超调量小,抗扰动能力强,稳态误差小.当系统参数不确定时,一旦负载突变,反馈线性化控制器对参数的依赖性和其变化的敏感性均增强.

  3. Predictive current control of permanent magnet synchronous motor based on linear active disturbance rejection control

    Science.gov (United States)

    Li, Kunpeng

    2017-01-01

    The compatibility problem between rapidity and overshooting in the traditional predictive current control structure is inevitable and difficult to solve by reason of using PI controller. A novel predictive current control (PCC) algorithm for permanent magnet synchronous motor (PMSM) based on linear active disturbance rejection control (LADRC) is presented in this paper. In order to displace PI controller, the LADRC strategy which consisted of linear state error feedback (LSEF) control algorithm and linear extended state observer (LESO), is designed based on the mathematic model of PMSM. The purpose of LSEF is to make sure fast response to load mutation and system uncertainties, and LESO is designed to estimate the uncertain disturbances. The principal structures of the proposed system are speed outer loop based on LADRC and current inner loop based on predictive current control. Especially, the instruction value of qaxis current in inner loop is derived from the control quantity which is designed in speed outer loop. The simulation is carried out in Matlab/Simulink software, and the results illustrate that the dynamic and static performances of proposed system are satisfied. Moreover the robust against model parameters mismatch is enhanced obviously.

  4. Language-based social feedback processing with randomized "senders": An ERP study.

    Science.gov (United States)

    Schindler, Sebastian; Kissler, Johanna

    2017-02-06

    Recently, several event-related potential (ERP) studies investigated the impact of sender attributions on language-based social feedback processing. Results showed very early responses to the social context, while interactions or effects of emotional content started later. However, in these studies, sender attribution was varied across blocks, possibly inducing unspecific, anticipatory effects. Here, who was giving feedback was disclosed simultaneously with the decision itself. Participants' ERPs differentiated between attributed senders starting with the early posterior negativity. P3 and late positive potential (LPP) amplitudes were also enlarged for the "human sender". Emotion effects occurred in the P3 and LPP time windows. Further, we found an interaction on the P3: "Human" emotional feedback was selectively amplified. Source analysis localized enhanced processing of "human"-generated feedback in visual areas from around 300 ms after feedback onset and from 400 ms also in temporal regions. Enhancement of "human" emotional feedback resulted from increased activations in the left visual word form area. These findings highlight that decoding who is giving feedback precedes content processing, both in blocked and in randomly alternating situations. Further, in quasi-realistic social contexts, processing of emotional content is selectively amplified. Finally, involvement of semantic language processing structures indicates reintegration of words in a salient context.

  5. Actin-Based Feedback Circuits in Cell Migration and Endocytosis

    Science.gov (United States)

    Wang, Xinxin

    In this thesis, we study the switch and pulse functions of actin during two important cellular processes, cell migration and endocytosis. Actin is an abundant protein that can polymerize to form a dendritic network. The actin network can exert force to push or bend the cell membrane. During cell migration, the actin network behaves like a switch, assembling mostly at one end or at the other end. The end with the majority of the actin network is the leading edge, following which the cell can persistently move in the same direction. The other end, with the minority of the actin network, is the trailing edge, which is dragged by the cell as it moves forward. When subjected to large fluctuations or external stimuli, the leading edge and the trailing edge can interchange and change the direction of motion, like a motion switch. Our model of the actin network in a cell reveals that mechanical force is crucial for forming the motion switch. We find a transition from single state symmetric behavior to switch behavior, when tuning parameters such as the force. The model is studied by both stochastic simulations, and a set of rate equations that are consistent with the simulations. Endocytosis is a process by which cells engulf extracellular substances and recycle the cell membrane. In yeast cells, the actin network is transiently needed to overcome the pressure difference across the cell membrane caused by turgor pressure. The actin network behaves like a pulse, which assembles and then disassembles within about 30 seconds. Using a stochastic model, we reproduce the pulse behaviors of the actin network and one of its regulatory proteins, Las17. The model matches green fluorescence protein (GFP) experiments for wild-type cells. The model also predicts some phenotypes that modify or diminish the pulse behavior. The phenotypes are verified with both experiments performed at Washington University and with other groups' experiments. We find that several feedback mechanisms are

  6. Exploring classroom feedback interactions around EAP writing : a data based model

    OpenAIRE

    Unlu, Zuleyha; Wharton, Sue

    2015-01-01

    This paper is based on case study research in the grounded theory tradition. In this paper we describe and theorise feedback interactions on EAP writing which were observed in classes in our institution. Working from detailed descriptions of feedback incidents and from interviews with teachers and students, we theorise a series of teacher and student actions. We argue that combinations of these actions are both reflective and constitutive of patterns of teacher-student relationships in the cl...

  7. Multisensor Distributed Track Fusion AlgorithmBased on Strong Tracking Filter and Feedback Integration1)

    Institute of Scientific and Technical Information of China (English)

    YANGGuo-Sheng; WENCheng-Lin; TANMin

    2004-01-01

    A new multisensor distributed track fusion algorithm is put forward based on combiningthe feedback integration with the strong tracking Kalman filter. Firstly, an effective tracking gateis constructed by taking the intersection of the tracking gates formed before and after feedback.Secondly, on the basis of the constructed effective tracking gate, probabilistic data association andstrong tracking Kalman filter are combined to form the new multisensor distributed track fusionalgorithm. At last, simulation is performed on the original algorithm and the algorithm presented.

  8. Non-linear states of a positive or negative refraction index material in a cavity with feedback

    Science.gov (United States)

    Mártin, D. A.; Hoyuelos, M.

    2010-06-01

    We study a system composed by a cavity with plane mirrors containing a positive or negative refraction index material with third order effective electric and magnetic non-linearities. The aim of the work is to present a general picture of possible non-linear states in terms of the relevant parameters of the system. The parameters are the ones that appear in a reduced description that has the form of the Lugiato-Lefever equation. This equation is obtained from two coupled non-linear Schrödinger equations for the electric and magnetic field amplitudes.

  9. Observer-based reliable stabilization of uncertain linear systems subject to actuator faults, saturation, and bounded system disturbances.

    Science.gov (United States)

    Fan, Jinhua; Zhang, Youmin; Zheng, Zhiqiang

    2013-11-01

    A matrix inequality approach is proposed to reliably stabilize a class of uncertain linear systems subject to actuator faults, saturation, and bounded system disturbances. The system states are assumed immeasurable, and a classical observer is incorporated for observation to enable state-based feedback control. Both the stability and stabilization of the closed-loop system are discussed and the closed-loop domain of attraction is estimated by an ellipsoidal invariant set. The resultant stabilization conditions in the form of matrix inequalities enable simultaneous optimization of both the observer gain and the feedback controller gain, which is realized by converting the non-convex optimization problem to an unconstrained nonlinear programming problem. The effectiveness of proposed design techniques is demonstrated through a linearized model of F-18 HARV around an operating point.

  10. Non-linear quenching of current fluctuations in a self-exciting homopolar dynamo, proved by feedback system theory

    Directory of Open Access Journals (Sweden)

    A. M. de Paor

    1998-01-01

    Full Text Available Hide (Nonlinear Processes in Geophysics, 1998 has produced a new mathematical model of a self-exciting homopolar dynamo driving a series- wound motor, as a continuing contribution to the theory of the geomagnetic field. By a process of exact perturbation analysis, followed by combination and partial solution of differential equations, the complete nonlinear quenching of current fluctuations reported by Hide in the case that a parameter ε has the value 1 is proved via the Popov theorem from feedback system stability theory.

  11. Automatic medical image annotation and keyword-based image retrieval using relevance feedback.

    Science.gov (United States)

    Ko, Byoung Chul; Lee, JiHyeon; Nam, Jae-Yeal

    2012-08-01

    This paper presents novel multiple keywords annotation for medical images, keyword-based medical image retrieval, and relevance feedback method for image retrieval for enhancing image retrieval performance. For semantic keyword annotation, this study proposes a novel medical image classification method combining local wavelet-based center symmetric-local binary patterns with random forests. For keyword-based image retrieval, our retrieval system use the confidence score that is assigned to each annotated keyword by combining probabilities of random forests with predefined body relation graph. To overcome the limitation of keyword-based image retrieval, we combine our image retrieval system with relevance feedback mechanism based on visual feature and pattern classifier. Compared with other annotation and relevance feedback algorithms, the proposed method shows both improved annotation performance and accurate retrieval results.

  12. An occupation-based video feedback intervention for improving self-awareness: protocol and rationale.

    Science.gov (United States)

    Schmidt, Julia; Fleming, Jennifer; Ownsworth, Tamara; Lannin, Natasha A

    2015-02-01

    Impaired self-awareness can limit rehabilitation outcomes for people with traumatic brain injury (TBI). Video feedback on occupational performance has been found to improve self-awareness after TBI when delivered according to specific principles. The purpose of this article is to describe an occupation-based video feedback intervention found to be effective in a randomized controlled trial to assist with translation into clinical practice. The intervention uses therapist-mediated video feedback on clients' occupational performance, aiming to facilitate self-reflection on performance and improve self-awareness. This paper describes the theoretical background, intervention principles, and protocol of the intervention. Therapists can use video feedback intervention, incorporating the principles in this article, to improve people's intellectual awareness and ability to recognize and correct errors during task performance after TBI without a negative impact on emotional status.

  13. Spintronic Oscillator Based on Spin-Current Feedback Using the Spin Hall Effect

    Science.gov (United States)

    Bhuktare, Swapnil; Singh, Hanuman; Bose, Arnab; Tulapurkar, Ashwin. A.

    2017-01-01

    We propose a radio-frequency nano-oscillator based on feedback of spin current into a magnetic tunnel junction (MTJ) with an in-plane magnetized pinned layer and an out-of-plane magnetized free layer. The MTJ is connected to a "feedback" strip of a material like tungsten with a giant spin Hall effect. On passing a dc current through the MTJ, the thermal fluctuations of its free layer produce an oscillatory voltage across itself owing to the magnetoresistance effect. This oscillatory voltage drives an oscillatory current into the tungsten strip which converts this charge current into spin current via the spin Hall effect and feeds it back to the MTJ. We show that this feedback can amplify the fluctuations further and drive the free layer into periodic precessional states. We also propose a way of implementing spin-current feedback by using a nanomagnet coupled to the free layer of the MTJ by dipolar magnetic field.

  14. Characteristics of recursive backstepping algorithm and active damping of oscillations in feedback linearization for electromechanical system with extended stability analysis and perturbation rejection.

    Science.gov (United States)

    Anand, V; Narendran, R

    2016-09-01

    In this paper, a technique for estimation of state variables and control of a class of electromechanical system is proposed. Initially, an attempt is made on rudimentary pole placement technique for the control of rotor position and angular velocity profiles of Permanent Magnet Stepper Motor. Later, an alternative approach is analyzed using feedback linearization method to reduce the error in tracking performances. A damping control scheme was additionally incorporated into the feedback linearization system in order to nullify the persistent oscillations present in the system. Furthermore, a robust backstepping controller with high efficacy is put forth to enhance the overall performance and to carry out disturbance rejection. The predominant advantage of this control technique is that it does not require the DQ Transformation of the motor dynamics. A Lyapunov candidate was employed to ensure global asymptotical stability criterion. Also, a nonlinear observer is presented to estimate the unknown states namely load torque and rotor angular velocity, even under load uncertainty conditions. Finally, the performances of all the aforementioned control schemes and estimation techniques are compared and analyzed extensively through simulation.

  15. Secondary access based on sensing and primary ARQ feedback in spectrum sharing systems

    KAUST Repository

    Hamza, Doha R.

    2012-04-01

    In the context of primary/secondary spectrum sharing, we propose a randomized secondary access strategy with access probabilities that are a function of both the primary automatic repeat request (ARQ) feedback and the spectrum sensing outcome. The primary terminal operates in a time slotted fashion and is active only when it has a packet to send. The primary receiver can send a positive acknowledgment (ACK) when the received packet is decoded correctly. Lack of ARQ feedback is interpreted as erroneous reception or inactivity. We call this the explicit ACK scheme. The primary receiver may also send a negative acknowledgment (NACK) when the packet is received in error. Lack of ARQ feedback is interpreted as an ACK or no-transmission. This is called the explicit NACK scheme. Under both schemes, when the primary feedback is interpreted as a NACK, the secondary user assumes that there will be retransmission in the next slot and accesses the channel with a certain probability. When the primary feedback is interpreted as an ACK, the secondary user accesses the channel with either one of two probabilities based on the sensing outcome. Under these settings, we find the three optimal access probabilities via maximizing the secondary throughput given a constraint on the primary throughput. We compare the performance of the explicit ACK and explicit NACK schemes and contrast them with schemes based on either sensing or primary ARQ feedback only. © 2012 IEEE.

  16. Support vector classification algorithm based on variable parameter linear programming

    Institute of Scientific and Technical Information of China (English)

    Xiao Jianhua; Lin Jian

    2007-01-01

    To solve the problems of SVM in dealing with large sample size and asymmetric distributed samples, a support vector classification algorithm based on variable parameter linear programming is proposed.In the proposed algorithm, linear programming is employed to solve the optimization problem of classification to decrease the computation time and to reduce its complexity when compared with the original model.The adjusted punishment parameter greatly reduced the classification error resulting from asymmetric distributed samples and the detailed procedure of the proposed algorithm is given.An experiment is conducted to verify whether the proposed algorithm is suitable for asymmetric distributed samples.

  17. Multi User Feedback System Based On Performance and Appraisal Using Fuzzy Logic Base System- Design and Implementation

    Directory of Open Access Journals (Sweden)

    Ameet.D.Shah

    2014-03-01

    Full Text Available In Multi-user Feedback support system or 3600 Feedback, data on the performance of an individual are collected systematically from a number of stakeholders and are used for improving performance. The 3600 Feedback approach provides a consistent management philosophy meeting the criterion outlined previously. The 3600 feedback based appraisal is a comprehensive method where in the feedback about the employee comes from all the sources that come into contact with the employee on his/her job. The respondents for an employee can be her/his peers, managers, subordinates team members, customers, suppliers and vendors. Hence anyone who comes into contact with the employee, the 3600 appraisal has four components that include self-appraisal, superior’s appraisal, subordinate’s appraisal student’s appraisal and peer’s appraisal.

  18. Effects of computer-based immediate feedback on foreign language listening comprehension and test-associated anxiety.

    Science.gov (United States)

    Lee, Shu-Ping; Su, Hui-Kai; Lee, Shin-Da

    2012-06-01

    This study investigated the effects of immediate feedback on computer-based foreign language listening comprehension tests and on intrapersonal test-associated anxiety in 72 English major college students at a Taiwanese University. Foreign language listening comprehension of computer-based tests designed by MOODLE, a dynamic e-learning environment, with or without immediate feedback together with the state-trait anxiety inventory (STAI) were tested and repeated after one week. The analysis indicated that immediate feedback during testing caused significantly higher anxiety and resulted in significantly higher listening scores than in the control group, which had no feedback. However, repeated feedback did not affect the test anxiety and listening scores. Computer-based immediate feedback did not lower debilitating effects of anxiety but enhanced students' intrapersonal eustress-like anxiety and probably improved their attention during listening tests. Computer-based tests with immediate feedback might help foreign language learners to increase attention in foreign language listening comprehension.

  19. Resonances of a nonlinear single-degree-of-freedom system with time delay in linear feedback control

    Energy Technology Data Exchange (ETDEWEB)

    El-Bassiouny, Atef F. [Mathematics Dept., Benha Univ., Benha (Egypt); El-Kholy, Salah [Dept. of Mathematics, Menoufia Univ., Shebin El-kom (Egypt)

    2010-05-15

    The primary and subharmonic resonances of a nonlinear single-degree-of-freedom system under feedback control with a time delay are studied by means of an asymptotic perturbation technique. Both external (forcing) and parametric excitations are included. By means of the averaging method and multiple scales method, two slow-flow equations for the amplitude and phase of the primary and subharmonic resonances and all other parameters are obtained. The steady state (fixed points) corresponding to a periodic motion of the starting system is investigated and frequency-response curves are shown. The stability of the fixed points is examined using the variational method. The effect of the feedback gains, the time-delay, the coefficient of cubic term, and the coefficients of external and parametric excitations on the steady-state responses are investigated and the results are presented as plots of the steady-state response amplitude versus the detuning parameter. The results obtained by two methods are in excellent agreement. (orig.)

  20. A multimedia retrieval framework based on semi-supervised ranking and relevance feedback.

    Science.gov (United States)

    Yang, Yi; Nie, Feiping; Xu, Dong; Luo, Jiebo; Zhuang, Yueting; Pan, Yunhe

    2012-04-01

    We present a new framework for multimedia content analysis and retrieval which consists of two independent algorithms. First, we propose a new semi-supervised algorithm called ranking with Local Regression and Global Alignment (LRGA) to learn a robust Laplacian matrix for data ranking. In LRGA, for each data point, a local linear regression model is used to predict the ranking scores of its neighboring points. A unified objective function is then proposed to globally align the local models from all the data points so that an optimal ranking score can be assigned to each data point. Second, we propose a semi-supervised long-term Relevance Feedback (RF) algorithm to refine the multimedia data representation. The proposed long-term RF algorithm utilizes both the multimedia data distribution in multimedia feature space and the history RF information provided by users. A trace ratio optimization problem is then formulated and solved by an efficient algorithm. The algorithms have been applied to several content-based multimedia retrieval applications, including cross-media retrieval, image retrieval, and 3D motion/pose data retrieval. Comprehensive experiments on four data sets have demonstrated its advantages in precision, robustness, scalability, and computational efficiency.

  1. Mobile robot nonlinear feedback control based on Elman neural network observer

    Directory of Open Access Journals (Sweden)

    Khaled Al-Mutib

    2015-12-01

    Full Text Available This article presents a new approach to control a wheeled mobile robot without velocity measurement. The controller developed is based on kinematic model as well as dynamics model to take into account parameters of dynamics. These parameters related to dynamic equations are identified using a proposed methodology. Input–output feedback linearization is considered with a slight modification in the mathematical expressions to implement the dynamic controller and analyze the nonlinear internal behavior. The developed controllers require sensors to obtain the states needed for the closed-loop system. However, some states may not be available due to the absence of the sensors because of the cost, the weight limitation, reliability, induction of errors, failure, and so on. Particularly, for the velocity measurements, the required accuracy may not be achieved in practical applications due to the existence of significant errors induced by stochastic or cyclical noise. In this article, Elman neural network is proposed to work as an observer to estimate the velocity needed to complete the full state required for the closed-loop control and account for all the disturbances and model parameter uncertainties. Different simulations are carried out to demonstrate the feasibility of the approach in tracking different reference trajectories in comparison with other paradigms.

  2. Laser-plasma-based linear collider using hollow plasma channels

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, C.B., E-mail: CBSchroeder@lbl.gov; Benedetti, C.; Esarey, E.; Leemans, W.P.

    2016-09-01

    A linear electron–positron collider based on laser-plasma accelerators using hollow plasma channels is considered. Laser propagation and energy depletion in the hollow channel is discussed, as well as the overall efficiency of the laser-plasma accelerator. Example parameters are presented for a 1-TeV and 3-TeV center-of-mass collider based on laser-plasma accelerators.

  3. Virtual Estimator for Piecewise Linear Systems Based on Observability Analysis

    Directory of Open Access Journals (Sweden)

    Ilse Cervantes

    2013-02-01

    Full Text Available This article proposes a virtual sensor for piecewise linear systems based on observability analysis that is in function of a commutation law related with the system’s outpu. This virtual sensor is also known as a state estimator. Besides, it presents a detector of active mode when the commutation sequences of each linear subsystem are arbitrary and unknown. For the previous, this article proposes a set of virtual estimators that discern the commutation paths of the system and allow estimating their output. In this work a methodology in order to test the observability for piecewise linear systems with discrete time is proposed. An academic example is presented to show the obtained results.

  4. Controlling halo-chaos via wavelet-based feedback

    Directory of Open Access Journals (Sweden)

    Jin-Qing Fang

    2002-01-01

    Full Text Available Halo-chaos in high-current accelerator has become one of the key issues because it can cause excessive radioactivity from the accelerators and significantly limits the applications of the new accelerators in industrial and other fields. Some general engineering methods for chaos control have been developed, but they generally are unsuccessful for halo-chaos suppression due to many technical constraints. In this article, controllability condition for beam halo-chaos is analyzed qualitatively. Then Particles-in-Cell (PIC simulations explore the nature of beam halo-chaos formation. A nonlinear control method and wavelet function feedback controller are proposed for controlling beam halo-chaos. After control of beam halo-chaos for initial proton beam with water bag distributions, the beam halo strength factor H is reduced to zero, and other statistical physical quantities of beam halo-chaos are doubly reduced. The results show that the developed methods in this paper are very effective for proton beam halo-chaos suppression. Potential application of the halo-chaos control method is finally pointed out.

  5. Negative base encoding in optical linear algebra processors

    Science.gov (United States)

    Perlee, C.; Casasent, D.

    1986-01-01

    In the digital multiplication by analog convolution algorithm, the bits of two encoded numbers are convolved to form the product of the two numbers in mixed binary representation; this output can be easily converted to binary. Attention is presently given to negative base encoding, treating base -2 initially, and then showing that the negative base system can be readily extended to any radix. In general, negative base encoding in optical linear algebra processors represents a more efficient technique than either sign magnitude or 2's complement encoding, when the additions of digitally encoded products are performed in parallel.

  6. A training-based scheme for communicating over unknown channels with feedback

    CERN Document Server

    Mahajan, Aditya

    2009-01-01

    We consider communication with noiseless feedback over a channel that is either BSC(p) or BSC(1-p); neither the transmitter nor the receiver know which one. The parameter $p \\in [0, 1/2]$ is known to both. We propose a variable length training-based scheme for this channel. The error exponent of this scheme is within a constant fraction of the best possible error exponent. Thus, contrary to popular belief, variable length training-based schemes need not have poor error exponents. Moreover, training-based schemes can preserve the main advantage of feedback -- an error exponent with non-zero slope at rates close to capacity.

  7. Active disturbance rejection based trajectory linearization control for hypersonic reentry vehicle with bounded uncertainties.

    Science.gov (United States)

    Shao, Xingling; Wang, Honglun

    2015-01-01

    This paper investigates a novel compound control scheme combined with the advantages of trajectory linearization control (TLC) and alternative active disturbance rejection control (ADRC) for hypersonic reentry vehicle (HRV) attitude tracking system with bounded uncertainties. Firstly, in order to overcome actuator saturation problem, nonlinear tracking differentiator (TD) is applied in the attitude loop to achieve fewer control consumption. Then, linear extended state observers (LESO) are constructed to estimate the uncertainties acting on the LTV system in the attitude and angular rate loop. In addition, feedback linearization (FL) based controllers are designed using estimates of uncertainties generated by LESO in each loop, which enable the tracking error for closed-loop system in the presence of large uncertainties to converge to the residual set of the origin asymptotically. Finally, the compound controllers are derived by integrating with the nominal controller for open-loop nonlinear system and FL based controller. Also, comparisons and simulation results are presented to illustrate the effectiveness of the control strategy.

  8. The impact of problem-solving feedback on team-based learning case responses.

    Science.gov (United States)

    Medina, Melissa S; Conway, Susan E; Davis-Maxwell, Tamra S; Webb, Ryan

    2013-11-12

    To determine the amount and type of feedback needed to improve pharmacy students' problem-solving skills using team-based learning (TBL) and a problem-solving rubric. A problem-solving rubric was developed to assess the ability of pharmacy students' to prioritize, organize, and defend the best and alternative options on TBL cases The study involved 3 groups of pharmacy students: second-year students in a cardiology class who received no feedback (control group), third-year students in an endocrinology class who received written feedback only, and third-year students in an endocrinology class who received written and verbal feedback. Students worked in groups on all TBL cases except the first and last one (beginning and end of course), which students completed independently as it served as a pretest and posttest. Significant improvements were seen in the ability of the third-year students who received verbal and written feedback to prioritize the information presented in the case and in their total score on the problem-solving rubric. Providing pharmacy students with written and verbal explanations may help them improve their problem-solving skills overall. During verbal feedback, faculty members can provide more examples of how to improve and can field questions if needed.

  9. Real-time information feedback based on a sharp decay weighted function

    Science.gov (United States)

    Chen, Bokui; Dong, Chuanfei; Liu, Yike; Tong, Wei; Zhang, Wenyao; Liu, Jie; Wang, Binghong

    2012-10-01

    Information feedback strategy, serving as the critical part of intelligent traffic systems, has been treated with growing emphasis. In recent years, a variety of feedback strategies have been proposed. Despite the fact that these strategies have been proved to enhance the traffic efficiency, we find that the road capacity has not been saturated and there is still plenty of room for improvement. Based on the analytic approximations, we found the reason why corresponding angle feedback strategy is superior to weighted congestion coefficient feedback strategy. Given that the sharp decay of the weighted coefficient is the key point, we proposed an efficient feedback strategy called the exponential function feedback strategy (EFFS). We applied it to both the symmetrical two-route model with two exits and that with a single exit. The simulation results indicate that, compared with other strategies, EFFS has decided numerical advantages in average flow, a physical quantity used for depicting the road capacity. Even more importantly, EFFS stands out for its convenient application as well as its fitness for modeling the rugged roads.

  10. Applied Research of Enterprise Cost Control Based on Linear Programming

    Directory of Open Access Journals (Sweden)

    Yu Shuo

    2015-01-01

    This paper researches the enterprise cost control through the linear programming model, and analyzes the restriction factors of the labor of enterprise production, raw materials, processing equipment, sales price, and other factors affecting the enterprise income, so as to obtain an enterprise cost control model based on the linear programming. This model can calculate rational production mode in the case of limited resources, and acquire optimal enterprise income. The production guiding program and scheduling arrangement of the enterprise can be obtained through calculation results, so as to provide scientific and effective guidance for the enterprise production. This paper adds the sensitivity analysis in the linear programming model, so as to learn about the stability of the enterprise cost control model based on linear programming through the sensitivity analysis, and verify the rationality of the model, and indicate the direction for the enterprise cost control. The calculation results of the model can provide a certain reference for the enterprise planning in the market economy environment, which have strong reference and practical significance in terms of the enterprise cost control.

  11. Train repathing in emergencies based on fuzzy linear programming.

    Science.gov (United States)

    Meng, Xuelei; Cui, Bingmou

    2014-01-01

    Train pathing is a typical problem which is to assign the train trips on the sets of rail segments, such as rail tracks and links. This paper focuses on the train pathing problem, determining the paths of the train trips in emergencies. We analyze the influencing factors of train pathing, such as transferring cost, running cost, and social adverse effect cost. With the overall consideration of the segment and station capability constraints, we build the fuzzy linear programming model to solve the train pathing problem. We design the fuzzy membership function to describe the fuzzy coefficients. Furthermore, the contraction-expansion factors are introduced to contract or expand the value ranges of the fuzzy coefficients, coping with the uncertainty of the value range of the fuzzy coefficients. We propose a method based on triangular fuzzy coefficient and transfer the train pathing (fuzzy linear programming model) to a determinate linear model to solve the fuzzy linear programming problem. An emergency is supposed based on the real data of the Beijing-Shanghai Railway. The model in this paper was solved and the computation results prove the availability of the model and efficiency of the algorithm.

  12. Single Feedback Predistortion Linearization Method for RF Power Amplifier%单路反馈射频功放预失真线性化方法

    Institute of Scientific and Technical Information of China (English)

    詹鹏; 秦开宇; 蔡顺燕

    2011-01-01

    该文基于记忆多项式模型,提出一种采用单路反馈的射频功放预失真线性化新方法,只需用正交解调后的IQ信号中的一路,就可完成对预失真器模型参数的获取.该方法可消除使用正交解调器所带来的增益和相位不平衡问题,且节省了一路反馈采样电路,在降低成本、简化设计的同时还能提高预失真线性化的性能.仿真和物理实验结果表明,该文提出的方法是正确的,能达到比较好的线性化效果.%Based on memory polynomial model, this paper proposes a new RF power amplifier predistortion linearization method using single feedback, which only needs the in-phase or quadrature component of the quadrature demodulated IQ signal, and it also can acquire the model parameters of predistorter. This method can eliminate the gain and phase imbalance problems caused by quadrature demodulator, and one feedback sampling circuit is saved, which can reduce the costs, simplify the system design, as well as improve the predistortion linearization performance. Simulation and experiment results show the correctness of the proposed method, which can achieve satisfied linearization performance.

  13. 基于输出反馈线性化的机械手随动控制%Tracking control of robot manipulators via output feedback linearization

    Institute of Scientific and Technical Information of China (English)

    费跃农; 吴青华

    2005-01-01

    A sliding mode perturbation observer (SPO) was designed for linearization of robot manipulators. It can estimate unmeasurable states and system perturbations including system nonlinearities, disturbances and unmodelled dynamics. With SPO, robot manipulator systems can be linearized and decoupled merely by joint angle feedback and the controller design does not need an accurate model of robot manipulators. Simulation studies were taken on a twolink robot manipulator to evaluate the proposed approach. The simulation results show that controllers with SPO have superior tracking performances, over a wide range of payloads, compared to sliding mode controllers using state feedback linearization.%为机械手线性化和随动控制设计了一种滑动模态扰动观测器.在观测系统状态的同时,估计由系统的非线性和模型的不确定性和外来的干扰所造成的广义扰动.它使非线性、强耦合的机械手系统可以仅靠关节角反馈实现线性化和解耦,且控制器的设计不依赖于机械手的精确模型.二连杆机械手仿真研究表明,在机械手荷载大范围变化的场合下,该控制器的随动控制性能优于采用全状态反馈线性化的控制器.

  14. Mass detection algorithm based on support vector machine and relevance feedback

    Institute of Scientific and Technical Information of China (English)

    Ying WANG; Xinbo GAO

    2008-01-01

    To improve the detection of mass with appearance that borders on the similarity between mass and density tissues in the breast,an support vector machine classifier based on typical features iS designed to classify the region of interest(ROI).Furthermore,relevance feedback is introduced to improve the performance of support vector machines.A new mass detection scheme based on the support vector machine and the relevance feedback is proposed.Simulation experiments on mammograms illustrate that the novel support vector machine classifier based on typical features can improve the detection performance of the featureless classifier by 5%,while the introduction of relevance feedback can further improve the detection performance to about 90%.

  15. Linear optical pulse compression based on temporal zone plates.

    Science.gov (United States)

    Li, Bo; Li, Ming; Lou, Shuqin; Azaña, José

    2013-07-15

    We propose and demonstrate time-domain equivalents of spatial zone plates, namely temporal zone plates, as alternatives to conventional time lenses. Both temporal intensity zone plates, based on intensity-only temporal modulation, and temporal phase zone plates, based on phase-only temporal modulation, are introduced and studied. Temporal zone plates do not exhibit the limiting tradeoff between temporal aperture and frequency bandwidth (temporal resolution) of conventional linear time lenses. As a result, these zone plates can be ideally designed to offer a time-bandwidth product (TBP) as large as desired, practically limited by the achievable temporal modulation bandwidth (limiting the temporal resolution) and the amount of dispersion needed in the target processing systems (limiting the temporal aperture). We numerically and experimentally demonstrate linear optical pulse compression by using temporal zone plates based on linear electro-optic temporal modulation followed by fiber-optics dispersion. In the pulse-compression experiment based on temporal phase zone plates, we achieve a resolution of ~25.5 ps over a temporal aperture of ~5.77 ns, representing an experimental TBP larger than 226 using a phase-modulation amplitude of only ~0.8π rad. We also numerically study the potential of these devices to achieve temporal imaging of optical waveforms and present a comparative analysis on the performance of different temporal intensity and phase zone plates.

  16. Systematic quality improvement in healthcare: clinical performance measurement and registry-based feedback

    NARCIS (Netherlands)

    van der Veer, S.N.

    2012-01-01

    The work in this thesis showed that some aspects of care quality cannot be fully captured by one measure, that the positive impact of registry-based feedback on clinical performance is not self-evident, and that it is difficult to build a strong evidence base on how this impact can be increased. Yet

  17. A Game-Based Assessment of Students' Choices to Seek Feedback and to Revise

    Science.gov (United States)

    Cutumisu, Maria; Chin, Doris B.; Schwartz, Daniel L.

    2014-01-01

    We introduce an educational game-based assessment that measures the choices students make while learning. We present Posterlet, a game designed to assess students' choices to seek negative feedback and to revise, in which students learn graphical design principles while creating posters. We validate our game-based assessment approach with three…

  18. Providing Feedback on Computer-Based Algebra Homework in Middle-School Classrooms

    Science.gov (United States)

    Fyfe, Emily R.

    2016-01-01

    Homework is transforming at a rapid rate with continuous advances in educational technology. Computer-based homework, in particular, is gaining popularity across a range of schools, with little empirical evidence on how to optimize student learning. The current aim was to test the effects of different types of feedback on computer-based homework.…

  19. Effectiveness of Feedback for Enhancing English Pronunciation in an ASR-Based CALL System

    Science.gov (United States)

    Wang, Y.-H.; Young, S. S.-C.

    2015-01-01

    This paper presents a study on implementing the ASR-based CALL (computer-assisted language learning based upon automatic speech recognition) system embedded with both formative and summative feedback approaches and using implicit and explicit strategies to enhance adult and young learners' English pronunciation. Two groups of learners including 18…

  20. Leadership Identity Development Through Reflection and Feedback in Team-Based Learning Medical Student Teams.

    Science.gov (United States)

    Alizadeh, Maryam; Mirzazadeh, Azim; Parmelee, Dean X; Peyton, Elizabeth; Mehrdad, Neda; Janani, Leila; Shahsavari, Hooman

    2017-07-28

    Studies on leadership identity development through reflection with Team-Based Learning (TBL) in medical student education are rare. We assumed that reflection and feedback on the team leadership process would advance the progression through leadership identity development stages in medical students within the context of classes using TBL. This study is a quasi-experimental design with pretest-posttest control group. The pretest and posttest were reflection papers of medical students about their experience of leadership during their TBL sessions. In the intervention group, TBL and a team-based, guided reflection and feedback on the team leadership process were performed at the end of all TBL sessions. In the other group, only TBL was used. The Stata 12 software was used. Leadership Identity was treated both as a categorical and quantitative variable to control for differences in baseline and gender variables. Chi-square, t tests, and linear regression analysis were performed. The population was a cohort of 2015-2016 medical students in a TBL setting at Tehran University of Medical Sciences, School of Medicine. Teams of four to seven students were formed by random sorting at the beginning of the academic year (intervention group n = 20 teams, control group n = 19 teams). At baseline, most students in both groups were categorized in the Awareness and Exploration stage of leadership identity: 51 (52%) in the intervention group and 59 (55%) in the control group: uncorrected χ(2)(3) = 15.6, design-based F(2.83, 108) = 4.87, p = .003. In the posttest intervention group, 36 (36%) were in exploration, 33 (33%) were in L-identified, 20 (20%) were in Leadership Differentiated, and 10 (10%) were in the Generativity. None were in the Awareness or Integration stages. In the control group, 3 (20%) were in Awareness, 56 (53%) were in Exploration, 35 (33%) were in Leader Identified, 13 (12%) were in Leadership Differentiated. None were in the Generativity and Integration stages

  1. Dynamic Output Feedback Robust MPC with Input Saturation Based on Zonotopic Set-Membership Estimation

    Directory of Open Access Journals (Sweden)

    Xubin Ping

    2016-01-01

    Full Text Available For quasi-linear parameter varying (quasi-LPV systems with bounded disturbance, a synthesis approach of dynamic output feedback robust model predictive control (OFRMPC with the consideration of input saturation is investigated. The saturated dynamic output feedback controller is represented by a convex hull involving the actual dynamic output controller and an introduced auxiliary controller. By taking both the actual output feedback controller and the auxiliary controller with a parameter-dependent form, the main optimization problem can be formulated as convex optimization. The consideration of input saturation in the main optimization problem reduces the conservatism of dynamic output feedback controller design. The estimation error set and bounded disturbance are represented by zonotopes and refreshed by zonotopic set-membership estimation. Compared with the previous results, the proposed algorithm can not only guarantee the recursive feasibility of the optimization problem, but also improve the control performance at the cost of higher computational burden. A nonlinear continuous stirred tank reactor (CSTR example is given to illustrate the effectiveness of the approach.

  2. Active Vibration Control of Container Cranes against Earthquake by the Use of LMI Based Mixed H2/H∞ State-Feedback Controller

    Directory of Open Access Journals (Sweden)

    C. Oktay Azeloglu

    2015-01-01

    Full Text Available This paper studies the design of a linear matrix inequality (LMI based mixed H2/H∞ state-feedback controller for vibration attenuation problem of seismic-excited container cranes. In order to show effectiveness of the designed controller, a six-degree-of-freedom container crane structural system is modeled using a spring-mass-damper subsystem. The system is then simulated against the real ground motion of El Centro and Northridge earthquakes. Finally, the time history of the crane parts displacements, accelerations, control forces, and frequency responses of both uncontrolled and controlled cases are presented. Additionally, the performance of the designed controller is also compared with a nominal state-feedback H∞ controller performance. Simulations of the designed controller show better seismic performance than a nominal state-feedback H∞ controller. Simulation results show that the designed controller is all effective in reducing vibration amplitudes of crane parts.

  3. Formation Feedback Applied to Behavior-Based Approach to Formation Keeping

    Institute of Scientific and Technical Information of China (English)

    苏治宝; 陆际联

    2004-01-01

    Approaches to the study of formation keeping for multiple mobile robots are analyzed and a behavior-based robot model is built in this paper. And, a kind of coordination architecture is presented, which is similar to the infantry squad organization and is used to realize multiple mobile robots to keep formations. Simulations verify the validity of the approach to keep formation, which combines the behavior-based method and formation feedback. The effects of formation feedback on the performance of the system are analyzed.

  4. Linear filtering of images based on properties of vision.

    Science.gov (United States)

    Algazi, V R; Ford, G E; Chen, H

    1995-01-01

    The design of linear image filters based on properties of human visual perception has been shown to require the minimization of criterion functions in both the spatial and frequency domains. We extend this approach to continuous filters of infinite support. For lowpass filters, this leads to the concept of an ideal lowpass image filter that provides a response that is superior perceptually to that of the classical ideal lowpass filter.

  5. A Spreadsheet-Based, Matrix Formulation Linear Programming Lesson

    DEFF Research Database (Denmark)

    Harrod, Steven

    2009-01-01

    The article focuses on the spreadsheet-based, matrix formulation linear programming lesson. According to the article, it makes a higher level of theoretical mathematics approachable by a wide spectrum of students wherein many may not be decision sciences or quantitative methods majors. Moreover......, it is consistent with the Arganbright Principles because the arrays and functions are clear in their operation and easily manipulated by the user....

  6. Graph-based linear scaling electronic structure theory

    CERN Document Server

    Niklasson, Anders M N; Negre, Christian F A; Cawkwell, Marc J; Swart, Pieter J; Mohd-Yusof, Jamal; Germann, Timothy C; Wall, Michael E; Bock, Nicolas; Djidjev, Hristo

    2016-01-01

    We show how graph theory can be combined with quantum theory to calculate the electronic structure of large complex systems. The graph formalism is general and applicable to a broad range of electronic structure methods and materials, including challenging systems such as biomolecules. The methodology combines well-controlled accuracy, low computational cost, and natural low-communication parallelism. This combination addresses substantial shortcomings of linear scaling electronic structure theory, in particular with respect to quantum-based molecular dynamics simulations.

  7. Research of optical rainfall sensor based on CCD linear array

    Institute of Scientific and Technical Information of China (English)

    YANG; Bifeng; LIU; Yuyan; LU; Ying; WU; Shangqian

    2015-01-01

    Rainfall monitoring is one of the most important meteorological observation elements for the disaster weather. The maintenance of current tipping bucket rain gauge and weighing type rain gauge is a critical issue. The optical rainfall sensor based on CCD linear array is mainly studied in this paper. Because of the maintenance-free time and good adaptability,it can be widely used in the automatic rainfall monitoring in severe environment and have a good perspective in using.

  8. Fuzzy support vector machines based on linear clustering

    Science.gov (United States)

    Xiong, Shengwu; Liu, Hongbing; Niu, Xiaoxiao

    2005-10-01

    A new Fuzzy Support Vector Machines (FSVMs) based on linear clustering is proposed in this paper. Its concept comes from the idea of linear clustering, selecting the data points near to the preformed hyperplane, which is formed on the training set including one positive and one negative training samples respectively. The more important samples near to the preformed hyperplane are selected by linear clustering technique, and the new FSVMs are formed on the more important data set. It integrates the merit of two kinds of FSVMs. The membership functions are defined using the relative distance between the data points and the preformed hyperplane during the training process. The fuzzy membership decision functions of multi-class FSVMs adopt the minimal value of all the decision functions of two-class FSVMs. To demonstrate the superiority of our methods, the benchmark data sets of machines learning databases are selected to verify the proposed FSVMs. The experimental results indicate that the proposed FSVMs can reduce the training data and running time, and its recognition rate is greater than or equal to that of FSVMs through selecting a suitable linear clustering parameter.

  9. Simulation of neurocomputing based on the photophobic reactions of Euglena with optical feedback stimulation.

    Science.gov (United States)

    Ozasa, Kazunari; Aono, Masashi; Maeda, Mizuo; Hara, Masahiko

    2010-05-01

    To explore possible forms of unconventional computers that have high capacities for adaptation and exploration, we propose a new approach to developing a biocomputer based on the photophobic reactions of microbes (Euglena gracilis), and perform the Monte-Carlo simulation of Euglena-based neural network computing, involving virtual optical feedback to the Euglena cells. The photophobic reactions of Euglena are obtained experimentally, and incorporated in the simulation, together with a feedback algorithm with a modified Hopfield-Tank model for solving a 4-city traveling salesman problem. The simulation shows high performances in terms of (1) reaching one of the best solutions of the problem, and (2) searching for a number of solutions via dynamic transition among the solutions. This dynamic transition is attributed to the fluctuation of state variables, global oscillation through feedback instability, and the one-by-one change of state variables.

  10. Lyapunov-based boundary feedback control in multi-reach canals

    Institute of Scientific and Technical Information of China (English)

    CEN LiHui; XI YuGeng

    2009-01-01

    This paper presents a Lyapunov-based approach to design the boundary feedback control for an open-channel network composed of a cascade of multi-reach canals, each described by a pair of Saint-Venant equations. The weighted sum of entropies of the multi-reaches is adopted to construct the Lyapunov function. The time derivative of the Lyapunov function is expressed by the water depth variations at the gate boundaries, based on which a class of boundary feedback controllers is presented to guarantee the local asymptotic closed-loop stability. The advantage of this approach is that only the water level depths at the gate boundaries are measured as the feedback.

  11.   Indirect versus direct feedback in computer-based Prism Adaptation Therapy

    DEFF Research Database (Denmark)

    Wilms, Inge Linda; Rytter, Hana Malá

    2010-01-01

      Prism Adaptation Therapy (PAT) is an intervention method in the treatment of the attention disorder neglect (Frassinetti, Angeli, Meneghello, Avanzi, & Ladavas, 2002; Rossetti, et al., 1998). The aim of this study was to investigate whether one session of PAT using a computer-attached touchscreen......-based implementation with an attached touchscreen. The session of PAT included a pre-exposure phase pointing at 30 targets without feedback; an exposure phase pointing at 90 targets with prism goggles and feedback; and a post-exposure phase pointing at 60 targets, with no goggles and no feedback.   The results...... have direct implications for future implementations of computer-based methods of treatment of visuospatial disorders and computer-assisted rehabilitation in general....

  12. Indirect versus direct feedback in computer-based Prism Adaptation Therapy

    DEFF Research Database (Denmark)

    Wilms, Inge Linda; Rytter, Hana Malá

    2010-01-01

    Prism Adaptation Therapy (PAT) is an intervention method in the treatment of the attention disorder neglect (Frassinetti, Angeli, Meneghello, Avanzi, & Ladavas, 2002; Rossetti, et al., 1998). The aim of this study was to investigate whether one session of PAT using a computer-attached touchscreen......-based implementation with an attached touchscreen. The session of PAT included a pre-exposure step pointing at 30 targets without feedback; an exposure step pointing at 90 targets with prism goggles and feedback; and a post-exposure step pointing at 60 targets, with no goggles and no feedback. The results indicate...... in the aftereffect. The findings have direct implications for future implementations of computer-based methods of treatment of visuospatial disorders and computer-assisted rehabilitation in general....

  13. Impact of a novel teaching method based on feedback, activity, individuality and relevance on students’ learning

    Science.gov (United States)

    Brooks, William S.; Laskar, Simone N.; Benjamin, Miles W.; Chan, Philip

    2016-01-01

    Objectives This study examines the perceived impact of a novel clinical teaching method based on FAIR principles (feedback, activity, individuality and relevance) on students’ learning on clinical placement. Methods This was a qualitative research study. Participants were third year and final year medical students attached to one UK vascular firm over a four-year period (N=108). Students were asked to write a reflective essay on how FAIRness approach differs from previous clinical placement, and its advantages and disadvantages. Essays were thematically analysed and globally rated (positive, negative or neutral) by two independent researchers. Results Over 90% of essays reported positive experiences of feedback, activity, individuality and relevance model.  The model provided multifaceted feedback; active participation; longitudinal improvement; relevance to stage of learning and future goals; structured teaching; professional development; safe learning environment; consultant involvement in teaching. Students perceived preparation for tutorials to be time intensive for tutors/students; a lack of teaching on medical sciences and direct observation of performance; more than once weekly sessions would be beneficial; some issues with peer and public feedback, relevance to upcoming exam and large group sizes. Students described negative experiences of “standard” clinical teaching. Conclusions Progressive teaching programmes based on the FAIRness principles, feedback, activity, individuality and relevance, could be used as a model to improve current undergraduate clinical teaching. PMID:26995588

  14. CPG-based Sensory Feedback Control for Bio-inspired Multimodal Swimming

    Directory of Open Access Journals (Sweden)

    Ming Wang

    2014-10-01

    Full Text Available Sensory feedback plays a very significant role in the generation of diverse and stable movements for animals. In this paper we describe our effort to develop a Central Pattern Generator (CPG-based sensory feedback control for the creation of multimodal swimming for a multi-articulated robotic fish in the context of neurocomputing. The proposed control strategy is composed of two phases: the upper decision-making and the automatic adjustment. According to the upper control commands and the sensory inputs, different swimming gaits are determined by a finite state machine algorithm. At the same time, the sensory feedback is exploited to shape the CPG coupling forms and control parameters. In the automatic adjustment phase, the CPG model with sensory feedback will adapt the environment autonomously. Simulation and underwater tests are further conducted to verify the presented control scheme. It is found that the CPG-based sensory feedback control method can effectively improve the manoeuvrability and adaptability of the robotic fish in water.

  15. Whole arm manipulation planning based on feedback velocity fields and sampling-based techniques.

    Science.gov (United States)

    Talaei, B; Abdollahi, F; Talebi, H A; Omidi Karkani, E

    2013-09-01

    Changing the configuration of a cooperative whole arm manipulator is not easy while enclosing an object. This difficulty is mainly because of risk of jamming caused by kinematic constraints. To reduce this risk, this paper proposes a feedback manipulation planning algorithm that takes grasp kinematics into account. The idea is based on a vector field that imposes perturbation in object motion inducing directions when the movement is considerably along manipulator redundant directions. Obstacle avoidance problem is then considered by combining the algorithm with sampling-based techniques. As experimental results confirm, the proposed algorithm is effective in avoiding jamming as well as obstacles for a 6-DOF dual arm whole arm manipulator. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

  16. A Parallel Encryption Algorithm Based on Piecewise Linear Chaotic Map

    Directory of Open Access Journals (Sweden)

    Xizhong Wang

    2013-01-01

    Full Text Available We introduce a parallel chaos-based encryption algorithm for taking advantage of multicore processors. The chaotic cryptosystem is generated by the piecewise linear chaotic map (PWLCM. The parallel algorithm is designed with a master/slave communication model with the Message Passing Interface (MPI. The algorithm is suitable not only for multicore processors but also for the single-processor architecture. The experimental results show that the chaos-based cryptosystem possesses good statistical properties. The parallel algorithm provides much better performance than the serial ones and would be useful to apply in encryption/decryption file with large size or multimedia.

  17. NEW VERSATILE CAMERA CALIBRATION TECHNIQUE BASED ON LINEAR RECTIFICATION

    Institute of Scientific and Technical Information of China (English)

    Pan Feng; Wang Xuanyin

    2004-01-01

    A new versatile camera calibration technique for machine vision using off-the-shelf cameras is described. Aimed at the large distortion of the off-the-shelf cameras, a new camera distortion rectification technology based on line-rectification is proposed. A full-camera-distortion model is introduced and a linear algorithm is provided to obtain the solution. After the camera rectification intrinsic and extrinsic parameters are obtained based on the relationship between the homograph and absolute conic. This technology needs neither a high-accuracy three-dimensional calibration block, nor a complicated translation or rotation platform. Both simulations and experiments show that this method is effective and robust.

  18. Optimal classifier feedback improves cost-benefit but not base-rate decision criterion learning in perceptual categorization.

    Science.gov (United States)

    Maddox, W Todd; Bohil, Corey J

    2005-03-01

    Unequal payoffs engender separate reward- and accuracy-maximizing decision criteria; unequal base rates do not. When payoffs are unequal, observers place greater emphasis on accuracy than is optimal. This study compares objective classifier (the objectively correct response) with optimal classifier feedback (the optimal classifier's response) when payoffs or base rates are unequal. It provides a critical test of Maddox and Bohil's (1998) competition between reward and accuracy maximization (COBRA) hypothesis, comparing it with a competition between reward and probability matching (COBRM) and a competition between reward and equal response frequencies (COBRE) hypothesis. The COBRA prediction that optimal classifier feedback leads to better decision criterion leaning relative to objective classifier feedback when payoffs are unequal, but not when base rates are unequal, was supported. Model-based analyses suggested that the weight placed on accuracy was reduced for optimal classifier feedback relative to objective classifier feedback. In addition, delayed feedback affected learning of the reward-maximizing decision criterion.

  19. Development of flank wear model of cutting tool by using adaptive feedback linear control system on machining AISI D2 steel and AISI 4340 steel

    Science.gov (United States)

    Orra, Kashfull; Choudhury, Sounak K.

    2016-12-01

    The purpose of this paper is to build an adaptive feedback linear control system to check the variation of cutting force signal to improve the tool life. The paper discusses the use of transfer function approach in improving the mathematical modelling and adaptively controlling the process dynamics of the turning operation. The experimental results shows to be in agreement with the simulation model and error obtained is less than 3%. The state space approach model used in this paper successfully check the adequacy of the control system through controllability and observability test matrix and can be transferred from one state to another by appropriate input control in a finite time. The proposed system can be implemented to other machining process under varying range of cutting conditions to improve the efficiency and observability of the system.

  20. Adjoint LMS (ALMS Algorithm Based Active Noise Control with Feedback Path Modeling

    Directory of Open Access Journals (Sweden)

    U Ramachandraiah,

    2010-12-01

    Full Text Available In active noise control (ANC systems, there exists an inherent feedback from the loudspeaker to the primary microphone. Adjoint least mean square (ALMS algorithm is known to be an alternative to the widely used filtered x LMS (FxLMS for reducing the computational complexity and memory requirements, especially in the case of multi-channel systems. Further FxLMS algorithm is based on the assumptionthat the order of the weighing filter and secondary path can be commuted which is not always true in practice. Though ALMS do not make such an assumption, neither FxLMS nor the ALMS algorithms onsider the feedback path effect that is inherent in ANC systems.We propose a feedback ANC system based on ALMS algorithm which is analogous to the system based on FxLMS. Detailed computational complexity analysis for addition and multiplication requirements ispresented and are compared with those of its counterpart to establish its usefulness. Simulation results show the convergence characteristics of the ALMS based ANC with feedback path modeling is on par with that based on FxLMS.

  1. Development of a linear induction motor based artificial muscle system.

    Science.gov (United States)

    Gruber, A; Arguello, E; Silva, R

    2013-01-01

    We present the design of a linear induction motor based on electromagnetic interactions. The engine is capable of producing a linear movement from electricity. The design consists of stators arranged in parallel, which produce a magnetic field sufficient to displace a plunger along its axial axis. Furthermore, the winding has a shell and cap of ferromagnetic material that amplifies the magnetic field. This produces a force along the length of the motor that is similar to that of skeletal muscle. In principle, the objective is to use the engine in the development of an artificial muscle system for prosthetic applications, but it could have multiple applications, not only in the medical field, but in other industries.

  2. Novel sucker rod pumping system based on linear motor technology

    Institute of Scientific and Technical Information of China (English)

    李立毅; 李立清; 吴红星; 胡余生; 邹积岩

    2004-01-01

    Obtaining petroleum at the cost of electrical energy is a common problem in almost all oil fields, and it is mainly caused by low duty radio of induction motor used in beam pumping units. Traditional beam-pumping units have many intrinsic disadvantages such as low efficiency, complex transmission devices, poor flexibility,tremendous volume and weight in long stroke, etc. Therefore, a novel direct driven linear electromagnetic pumping unit (EMPU) has been developed by combining oil extraction technology with linear motor technology. The thrust of EMPU matches the changing of suspension center load to improve the system efficiency and cut down the consumption of energy. Based on previous experience, a small-scale prototype was developed and a simulation was conducted with it. Both theoretical analyses and experimental study showed that the problems exiting in beam pumping units can be solved with EMPU system, and this is a new method which can be used to solve high energy waste in oil fields.

  3. Feedback-based probabilistic category learning is selectively impaired in attention/hyperactivity deficit disorder.

    Science.gov (United States)

    Gabay, Yafit; Goldfarb, Liat

    2017-07-01

    Although Attention-Deficit Hyperactivity Disorder (ADHD) is closely linked to executive function deficits, it has recently been attributed to procedural learning impairments that are quite distinct from the former. These observations challenge the ability of the executive function framework solely to account for the diverse range of symptoms observed in ADHD. A recent neurocomputational model emphasizes the role of striatal dopamine (DA) in explaining ADHD's broad range of deficits, but the link between this model and procedural learning impairments remains unclear. Significantly, feedback-based procedural learning is hypothesized to be disrupted in ADHD because of the involvement of striatal DA in this type of learning. In order to test this assumption, we employed two variants of a probabilistic category learning task known from the neuropsychological literature. Feedback-based (FB) and paired associate-based (PA) probabilistic category learning were employed in a non-medicated sample of ADHD participants and neurotypical participants. In the FB task, participants learned associations between cues and outcomes initially by guessing and subsequently through feedback indicating the correctness of the response. In the PA learning task, participants viewed the cue and its associated outcome simultaneously without receiving an overt response or corrective feedback. In both tasks, participants were trained across 150 trials. Learning was assessed in a subsequent test without a presentation of the outcome or corrective feedback. Results revealed an interesting disassociation in which ADHD participants performed as well as control participants in the PA task, but were impaired compared with the controls in the FB task. The learning curve during FB training differed between the two groups. Taken together, these results suggest that the ability to incrementally learn by feedback is selectively disrupted in ADHD participants. These results are discussed in relation to both

  4. Feedback-based error monitoring processes during musical performance: an ERP study.

    Science.gov (United States)

    Katahira, Kentaro; Abla, Dilshat; Masuda, Sayaka; Okanoya, Kazuo

    2008-05-01

    Auditory feedback is important in detecting and correcting errors during sound production when a current performance is compared to an intended performance. In the context of vocal production, a forward model, in which a prediction of action consequence (corollary discharge) is created, has been proposed to explain the dampened activity of the auditory cortex while producing self-generated vocal sounds. However, it is unclear how auditory feedback is processed and what neural mechanism underlies the process during other sound production behavior, such as musical performances. We investigated the neural correlates of human auditory feedback-based error detection using event-related potentials (ERPs) recorded during musical performances. Keyboard players of two different skill levels played simple melodies using a musical score. During the performance, the auditory feedback was occasionally altered. Subjects with early and extensive piano training produced a negative ERP component N210, which was absent in non-trained players. When subjects listened to music that deviated from a corresponding score without playing the piece, N210 did not emerge but the imaginary mismatch negativity (iMMN) did. Therefore, N210 may reflect a process of mismatch between the intended auditory image evoked by motor activity, and actual auditory feedback.

  5. A Fuzzy PI Speed Controller based on Feedback Compensation Strategy for PMSM

    Directory of Open Access Journals (Sweden)

    Ou Sheng

    2015-05-01

    Full Text Available in order to solve the problem of robustness or anti-disturbance of the traditional PI speed controller in the permanent magnet synchronous motor. A fuzzy PI speed controller based on load torque feedback compensation is proposed for the permanent magnet synchronous motor. The combination of fuzzy PI control strategy and load feedback compensation method can enhance the robustness and disturbance rejection of the speed loop. According to the validated results of simulation and experiments, by using this PMSM speed controller, the robustness of the system speed control was enhanced markedly, and the capacity of anti-disturbance was also improved significantly.

  6. A Coherence Preservation Control Strategy in Cavity QED Based on Classical Quantum Feedback

    Directory of Open Access Journals (Sweden)

    Ming Li

    2013-01-01

    Full Text Available For eliminating the unexpected decoherence effect in cavity quantum electrodynamics (cavity QED, the transfer function of Rabi oscillation is derived theoretically using optical Bloch equations. In particular, the decoherence in cavity QED from the atomic spontaneous emission is especially considered. A feedback control strategy is proposed to preserve the coherence through Rabi oscillation stabilization. In the scheme, a classical quantum feedback channel for the quantum information acquisition is constructed via the quantum tomography technology, and a compensation system based on the root locus theory is put forward to suppress the atomic spontaneous emission and the associated decoherence. The simulation results have proved its effectiveness and superiority for the coherence preservation.

  7. Remote sensing image fusion based on Bayesian linear estimation

    Institute of Scientific and Technical Information of China (English)

    GE ZhiRong; WANG Bin; ZHANG LiMing

    2007-01-01

    A new remote sensing image fusion method based on statistical parameter estimation is proposed in this paper. More specially, Bayesian linear estimation (BLE) is applied to observation models between remote sensing images with different spatial and spectral resolutions. The proposed method only estimates the mean vector and covariance matrix of the high-resolution multispectral (MS) images, instead of assuming the joint distribution between the panchromatic (PAN) image and low-resolution multispectral image. Furthermore, the proposed method can enhance the spatial resolution of several principal components of MS images, while the traditional Principal Component Analysis (PCA) method is limited to enhance only the first principal component. Experimental results with real MS images and PAN image of Landsat ETM+ demonstrate that the proposed method performs better than traditional methods based on statistical parameter estimation,PCA-based method and wavelet-based method.

  8. Formative Feedback through Summative Tutorial-Based Assessments: The Relationship to Student Performance

    Science.gov (United States)

    Perera, Luckmika; Nguyen, Hoa; Watty, Kim

    2014-01-01

    This paper investigates the effectiveness (measured using assignment and examination performance) of an assessment design incorporating formative feedback through summative tutorial-based assessments to improve student performance, in a second-year Finance course at an Australian university. Data was collected for students who were enrolled in an…

  9. Controlling the Beam Halo-Chaos via Wavelet-Based Feedback Periodically

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In our recent work, worth mentioning in particular is the wavelet-based feedback controller, which works much better than the others for controlling the proton beam haio-chaos, where the master wavelet function isor, in a simplified form,and generalized form:(1)(2)(3)where a and b are scaling and translation constants, respectively. C is a selected constant. The

  10. Web-Based Teacher Training and Coaching/Feedback: A Case Study

    Science.gov (United States)

    Wilczynski, Susan M.; Labrie, Allison; Baloski, Ann; Kaake, Amanda; Marchi, Nick; Zoder-Martell, Kimberly

    2017-01-01

    The present case study evaluated web-based training with coaching and feedback delivered through videoconferencing software to increase teacher use of behavioral methods associated with increased compliance. The participant, a preschool special education teacher, increased both her knowledge of efficacious interventions for autism spectrum…

  11. Clarity, Consistency and Communication: Using Enhanced Dialogue to Create a Course-Based Feedback Strategy

    Science.gov (United States)

    Nixon, Sarah; Brooman, Simon; Murphy, Becky; Fearon, Damien

    2017-01-01

    This article examines the outcomes of a study across four discipline areas in order to develop course-based assessment strategies in closer cooperation with students. Second-year students (n = 48) from different disciplines were engaged in two phases of activity-orientated workshops. Phase 1 sought their perceptions of feedback. Phase 2 saw…

  12. Evaluation of Web-Based and Counselor-Delivered Feedback Interventions for Mandated College Students

    Science.gov (United States)

    Doumas, Diana M.; Workman, Camille R.; Navarro, Anabel; Smith, Diana

    2011-01-01

    This study evaluated the efficacy of 2 brief personalized feedback interventions aimed at reducing drinking among mandated college students. Results indicated significant reductions in drinking for students in both conditions. Findings provide support for web-based interventions for mandated college students. (Contains 1 table.)

  13. Genetic Algorithm-Based Relevance Feedback for Image Retrieval Using Local Similarity Patterns.

    Science.gov (United States)

    Stejic, Zoran; Takama, Yasufumi; Hirota, Kaoru

    2003-01-01

    Proposes local similarity pattern (LSP) as a new method for computing digital image similarity. Topics include optimizing similarity computation based on genetic algorithm; relevance feedback; and an evaluation of LSP on five databases that showed an increase in retrieval precision over other methods for computing image similarity. (Author/LRW)

  14. Tracking control and synchronization of chaotic systems based upon sampled-data feedback

    Institute of Scientific and Technical Information of China (English)

    陈士华; 刘杰; 谢进; 陆君安

    2002-01-01

    A novel tracking control and synchronization method is proposed based upon sampled-data feedback. This methodcan make a chaotic system approach any desired smooth orbit and synchronize the driving system and the responsesystem, both in the same structure and in diverse structures. Finally, a numerical simulation with a Lorenz system isprovided for the purpose of illustration and verification.

  15. Factors Affecting Learning of Vector Math from Computer-Based Practice: Feedback Complexity and Prior Knowledge

    Science.gov (United States)

    Heckler, Andrew F.; Mikula, Brendon D.

    2016-01-01

    In experiments including over 450 university-level students, we studied the effectiveness and time efficiency of several levels of feedback complexity in simple, computer-based training utilizing static question sequences. The learning domain was simple vector math, an essential skill in introductory physics. In a unique full factorial design, we…

  16. Effects of Reading Curriculum-Based Measurement (R-CBM) Teacher Feedback in General Education Classrooms

    Science.gov (United States)

    Graney, Suzanne Bamonto; Shinn, Mark R.

    2005-01-01

    This study examined the effects of teacher feedback from Reading Curriculum-Based Measurement (R-CBM) progress results for low-performing students in general education classrooms. Participants included 44 second-grade teachers and 184 students in their low reading groups. After 5 weeks of progress monitoring, teachers in the two experimental…

  17. A feedback-based model for CSR assessment and materiality analysis

    DEFF Research Database (Denmark)

    Calabrese, Armando; Costa, Roberta; Rosati, Francesco

    2015-01-01

    Current CSR literature offers little insight into how to engage customers and other stakeholders about their CSR expectations and perceptions. The aim of this paper is to propose a model for CSR evaluation and planning based on the classification of customer CSR feedback through the comparison of...

  18. Developing Business Management Students' Persuasive Writing through Blog-Based Peer-Feedback

    Science.gov (United States)

    Sayed, Osama H.

    2010-01-01

    The present study attempted to investigate the effect of using blog-based peer feedback on the persuasive writing of EFL business management students at the community college in Bisha, King Khalid University, Saudi Arabia. The study used a pre-test/post-test experimental and control group design. An experimental group and a control group were…

  19. "Posterlet": A Game-Based Assessment of Children's Choices to Seek Feedback and to Revise

    Science.gov (United States)

    Cutumisu, Maria; Blair, Kristen P.; Chin, Doris B.; Schwartz, Daniel L.

    2015-01-01

    We introduce one instance of a game-based assessment designed to measure students' self-regulated learning choices. We describe our overarching measurement strategy and we present "Posterlet", an assessment game in which students design posters and learn graphic design principles from feedback. We designed "Posterlet" to assess…

  20. Measurement of stress-induced birefringence in glasses based on reflective laser feedback effect

    Science.gov (United States)

    Haisha, Niu; YanXiong, Niu; Jiyang, Li

    2017-02-01

    A glass birefringence measurement system utilizing the reflective laser feedback (RLF) effect is presented. The measurement principle is analyzed based on the equivalent cavity of a Fabry-Perot interferometer, and the experiments are conducted with a piece of quartz glass with applied extrusion force. In the feedback system, aluminum film used as a feedback mirror is affixed to the back of the sample. When the light is reflected back into the cavity, as the reinjected light is imprinted with the birefringence information in the sample, the gain and polarization states of the laser are modulated. The variation of optical power and polarization states hopping is monitored to obtain the magnitude of the stress. The system has advantages such as simplicity and low-cost with a precision of 1.9 nm. Moreover, by adjusting the position of the aluminum, large-area samples can be measured anywhere at any place.

  1. AIRS Observations Based Evaluation of Relative Climate Feedback Strengths on a GCM Grid-Scale

    Science.gov (United States)

    Molnar, G. I.; Susskind, J.

    2012-12-01

    -term climate feedbacks due to global warming, for example. Nevertheless, one should take more confidence of greenhouse warming predictions of those GCMs that reproduce the (high quality observations-based) shorter-term feedback-relationships the best.

  2. Parameter Optimization of Linear Quadratic Controller Based on Genetic Algorithm

    Institute of Scientific and Technical Information of China (English)

    LI Jimin; SHANG Chaoxuan; ZOU Minghu

    2007-01-01

    The selection of weighting matrix in design of the linear quadratic optimal controller is an important topic in the control theory. In this paper, an approach based on genetic algorithm is presented for selecting the weighting matrix for the optimal controller. Genetic algorithm is adaptive heuristic search algorithm premised on the evolutionary ideas of natural selection and genetic. In this algorithm, the fitness function is used to evaluate individuals and reproductive success varies with fitness. In the design of the linear quadratic optimal controller, the fitness function has relation to the anticipated step response of the system. Not only can the controller designed by this approach meet the demand of the performance indexes of linear quadratic controller, but also satisfy the anticipated step response of close-loop system. The method possesses a higher calculating efficiency and provides technical support for the optimal controller in engineering application. The simulation of a three-order single-input single-output (SISO) system has demonstrated the feasibility and validity of the approach.

  3. Feedback for reinforcement learning based brain-machine interfaces using confidence metrics.

    Science.gov (United States)

    Prins, Noeline W; Sanchez, Justin C; Prasad, Abhishek

    2017-06-01

    For brain-machine interfaces (BMI) to be used in activities of daily living by paralyzed individuals, the BMI should be as autonomous as possible. One of the challenges is how the feedback is extracted and utilized in the BMI. Our long-term goal is to create autonomous BMIs that can utilize an evaluative feedback from the brain to update the decoding algorithm and use it intelligently in order to adapt the decoder. In this study, we show how to extract the necessary evaluative feedback from a biologically realistic (synthetic) source, use both the quantity and the quality of the feedback, and how that feedback information can be incorporated into a reinforcement learning (RL) controller architecture to maximize its performance. Motivated by the perception-action-reward cycle (PARC) in the brain which links reward for cognitive decision making and goal-directed behavior, we used a reward-based RL architecture named Actor-Critic RL as the model. Instead of using an error signal towards building an autonomous BMI, we envision to use a reward signal from the nucleus accumbens (NAcc) which plays a key role in the linking of reward to motor behaviors. To deal with the complexity and non-stationarity of biological reward signals, we used a confidence metric which was used to indicate the degree of feedback accuracy. This confidence was added to the Actor's weight update equation in the RL controller architecture. If the confidence was high (>0.2), the BMI decoder used this feedback to update its parameters. However, when the confidence was low, the BMI decoder ignored the feedback and did not update its parameters. The range between high confidence and low confidence was termed as the 'ambiguous' region. When the feedback was within this region, the BMI decoder updated its weight at a lower rate than when fully confident, which was decided by the confidence. We used two biologically realistic models to generate synthetic data for MI (Izhikevich model) and NAcc (Humphries

  4. Feedback for reinforcement learning based brain-machine interfaces using confidence metrics

    Science.gov (United States)

    Prins, Noeline W.; Sanchez, Justin C.; Prasad, Abhishek

    2017-06-01

    Objective. For brain-machine interfaces (BMI) to be used in activities of daily living by paralyzed individuals, the BMI should be as autonomous as possible. One of the challenges is how the feedback is extracted and utilized in the BMI. Our long-term goal is to create autonomous BMIs that can utilize an evaluative feedback from the brain to update the decoding algorithm and use it intelligently in order to adapt the decoder. In this study, we show how to extract the necessary evaluative feedback from a biologically realistic (synthetic) source, use both the quantity and the quality of the feedback, and how that feedback information can be incorporated into a reinforcement learning (RL) controller architecture to maximize its performance. Approach. Motivated by the perception-action-reward cycle (PARC) in the brain which links reward for cognitive decision making and goal-directed behavior, we used a reward-based RL architecture named Actor-Critic RL as the model. Instead of using an error signal towards building an autonomous BMI, we envision to use a reward signal from the nucleus accumbens (NAcc) which plays a key role in the linking of reward to motor behaviors. To deal with the complexity and non-stationarity of biological reward signals, we used a confidence metric which was used to indicate the degree of feedback accuracy. This confidence was added to the Actor’s weight update equation in the RL controller architecture. If the confidence was high (>0.2), the BMI decoder used this feedback to update its parameters. However, when the confidence was low, the BMI decoder ignored the feedback and did not update its parameters. The range between high confidence and low confidence was termed as the ‘ambiguous’ region. When the feedback was within this region, the BMI decoder updated its weight at a lower rate than when fully confident, which was decided by the confidence. We used two biologically realistic models to generate synthetic data for MI (Izhikevich

  5. A Kalman decomposition to detect temporal linear system srtucture

    NARCIS (Netherlands)

    Willigenburg, Van L.G.; Koning, De W.L.

    2015-01-01

    Feedback controllers for non-linear systems are often based on a linearized dynamic model. Such a linearized model may be temporarily uncontrollable and/or unreconstructable. This paper introduces the so-called differential Kalman decomposition of time-varying linear systems. It is based on

  6. A comparative study of linear and region based diagrams

    Directory of Open Access Journals (Sweden)

    Björn Gottfried

    2015-06-01

    Full Text Available There are two categories of objects spatial information science investigates: actual objects and their spatial properties, such as in geography, and abstract objects which are employed metaphorically, as for visual languages. A prominent example of the latter are diagrams that model knowledge of some domain. Different aspects of diagrams are of interest, including their formal properties or how human users work with them, for example, with diagrams representing sets. The literature about diagrammatic systems for the representation of sets shows a dominance of region-based diagrams like Euler circles and Venn diagrams. The effectiveness of these diagrams, however, is limited because region-based diagrams become quite complex for more then three sets. By contrast, linear diagrams are not equally prevalent but enable the representation of a greater number of sets without getting cluttered. Cluttered diagrams exhibit inherent complexity due to overlapping objects, irrelevant details, or other reasons that impinge upon their legibility. This study contrasts both types of diagrammatic systems and investigates whether the performance of users differs for both kinds of diagrams. A significant difference can be shown regarding the number of diagrams that can be drawn within a fixed period of time and regarding the number of errors made. The results indicate that linear diagrams are more effective by being more restrictive and because region based diagrams show much clutter due to overlapping, coincident, and tangentially touching contours, as well as an overwhelming number of empty zones. Linear diagrams are less prone to errors and do not suffer from clutter.

  7. Adult age differences in learning and generalization of feedback-based associations.

    Science.gov (United States)

    Simon, Jessica R; Gluck, Mark A

    2013-12-01

    Feedback-based associative learning (e.g., acquiring new associations from positive or negative outcomes) and generalization (e.g., applying past learning to new settings) are important cognitive skills that enable people to make economic decisions or social judgments. This ability to acquire new skills based on feedback and transfer those experiences to predict positive outcomes in novel situations is essential at all ages, but especially among older adults who must continually adapt to new people, environments, and technologies. Ample evidence from animal work, clinical research, and computational modeling has demonstrated that feedback-based associative learning is sensitive to basal ganglia dysfunction and generalization to medial temporal lobe dysfunction. This dissociation is relevant because of recent evidence that has suggested healthy aging compromises the basal ganglia system earlier than the medial temporal lobes. However, few studies have investigated how healthy aging influences these cognitive processes. Here, we examined both feedback-based associative learning and generalization in younger, middle-aged, and older adults using a computerized acquired equivalence task. Results revealed a significant effect of age group on feedback-based associative learning, consistent with evidence of persistent age-related declines in the basal ganglia. In contrast, generalization was spared in all but the oldest adult group, likely reflecting preserved medial temporal lobe function until advanced old age. Our findings add behavioral evidence to the emerging view that healthy aging affects the striatal system before the medial temporal lobes. Although further evidence is needed, this finding may shed light on the possible time course of neural system dysfunction in healthy aging. PsycINFO Database Record (c) 2013 APA, all rights reserved.

  8. Rateless feedback codes

    DEFF Research Database (Denmark)

    Sørensen, Jesper Hemming; Koike-Akino, Toshiaki; Orlik, Philip

    2012-01-01

    This paper proposes a concept called rateless feedback coding. We redesign the existing LT and Raptor codes, by introducing new degree distributions for the case when a few feedback opportunities are available. We show that incorporating feedback to LT codes can significantly decrease both...... the coding overhead and the encoding/decoding complexity. Moreover, we show that, at the price of a slight increase in the coding overhead, linear complexity is achieved with Raptor feedback coding....

  9. Active Probing Feedback based Self Configurable Intelligent Distributed Antenna System

    DEFF Research Database (Denmark)

    Kumar, Ambuj

    challenge through a viable solution that is based on injecting intelligence and services in parallel layers through a Distributed Antenna Systems (DAS) network. This approach would enable the remote sites to acquire intelligence and a resource pool at the same time, thereby managing the network dynamics...... as Self Configurable Distributed Antenna System (SCIDAS)....... collectively as Place Time Coverage & Capacity (PTC2). The dissertation proves through the concept of the PTC2 that the network performance can severely be degraded by the excessive and unrealistic site demands, the network management inefficiency, and the consequence of the accumulation of subscribers...

  10. Measurement of spatial object's exterior attitude based on linear CCD

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    It is difficult to realize real-time measurement of exterior attitude by the traditional systems based on the area image sensor which have conflict between speed and accuracy.The subsystem for three-dimensional (3D) coordinate rcconstruction of point target (S3DCRPT) which is composed of three one-dimensional (1D) cameras based on linear charge-coupled device (CCD) can determine the distant light spots' spatial position. The attitude angle of the measured object is determined by the spatial solution while the coordinate reconstruction is separately carried on by the S3DCRPT with some point cooperation targets (PCTs) on the measured object. A new optical system is designed to solve the interference problem with one-to-one relationship between the PCTs and the S3DCRPT optical subsystems,which improves the measurement accuracy and saves space. The mathematical model of the attitude measurement is established,and partial and global calibrations are realized for the multi-camera attitude measurement system.The test results show the feasibility of the exterior attitude measurement based on linear CCD.

  11. Applied research of quantum information based on linear optics

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xiao-Ye

    2016-08-01

    This thesis reports on outstanding work in two main subfields of quantum information science: one involves the quantum measurement problem, and the other concerns quantum simulation. The thesis proposes using a polarization-based displaced Sagnac-type interferometer to achieve partial collapse measurement and its reversal, and presents the first experimental verification of the nonlocality of the partial collapse measurement and its reversal. All of the experiments are carried out in the linear optical system, one of the earliest experimental systems to employ quantum communication and quantum information processing. The thesis argues that quantum measurement can yield quantum entanglement recovery, which is demonstrated by using the frequency freedom to simulate the environment. Based on the weak measurement theory, the author proposes that white light can be used to precisely estimate phase, and effectively demonstrates that the imaginary part of the weak value can be introduced by means of weak measurement evolution. Lastly, a nine-order polarization-based displaced Sagnac-type interferometer employing bulk optics is constructed to perform quantum simulation of the Landau-Zener evolution, and by tuning the system Hamiltonian, the first experiment to research the Kibble-Zurek mechanism in non-equilibrium kinetics processes is carried out in the linear optical system.

  12. 我国财政收支的因果关系研究--Linear Feedback Approach的应用

    Institute of Scientific and Technical Information of China (English)

    何秋仙; 楼迎军

    2005-01-01

    财政理论将一国财政收入与支出的关系区分为"量入为出(Tax-and-spend)"、"量出为入(Spend-and -Tax)"和"财政同步(Fiscal Synchronization)"三种关系.我国的财政收支结构和指导原则在改革开放后发生了深刻的变化,逐步接受了主流的西方宏观经济学和公共金融学的理论与政策.本文以我国1978年~2003年的财政收入和支出时间序列为样本,结合我国实际GDP时间序列,在单位根检验和协整检验的基础上,利用条件线性回归(conditional linear regression)方法来定量分析我国财政收支的因果关系.研究结果表明,相对而言,我国的财政运行机制的财政同步特性最为明显,一定程度上的"量入为出"的财政因果关系也得到了实证证据的支持.

  13. Assessing Online Textual Feedback to Support Student Intrinsic Motivation Using a Collaborative Text-Based Dialogue System: A Qualitative Study

    Science.gov (United States)

    Shroff, Ronnie H.; Deneen, Christopher

    2011-01-01

    This paper assesses textual feedback to support student intrinsic motivation using a collaborative text-based dialogue system. A research model is presented based on research into intrinsic motivation, and the specific construct of feedback provides a framework for the model. A qualitative research methodology is used to validate the model.…

  14. PSO Based State Feedback Controller Design for SVC to Enhance the Stability of Power System

    Directory of Open Access Journals (Sweden)

    Saeid Jalilzadeh

    2012-08-01

    Full Text Available SVC is one of the most significant devices in FACTS technology, which is used in parallel compensation, enhancing the transient stability, limiting the low frequency oscillations and, etc. designing a proper controller is effective in operation of SVC. In this paper, a simplified analysis of the effect of a SVC on the stability of a Single Machine Infinite Bus (SMIB system is presented. The SVC which is located at the terminal of the generator has the state feedback controller in which the coefficients of state feedback are optimized by the Particle Swarm Optimization (PSO algorithm in order to damp the Low Frequency Oscillations (LFO. The equations that describe the proposed system have been linearized, and then the optimum state feedback controller has been designed for SVC which its optimal coefficients have been earned by PSO algorithm. The system with proposed controller has been simulated for a special disturbance in nominal loading condition. Thereafter, for three states viz light loading condition, normal loading condition and heavy loading condition, to show the robustness of the proposed controller, the previous disturbance has been applied again. Then the dynamic responses of the generator have been presented. The simulation results showed that the system composed with proposed controller has a suitable operation in fast damping of oscillations of the power system. to ensure stability and tracking. Simulations is carried out to verify the theoretical results.

  15. Model-based Optimization and Feedback Control of the Current Density Profile Evolution in NSTX-U

    Science.gov (United States)

    Ilhan, Zeki Okan

    trajectories and analyzing the resulting plasma evolution. Finally, the proposed control-oriented model is embedded in feedback control schemes based on optimal control and Model Predictive Control (MPC) approaches. Integrators are added to the standard Linear Quadratic Gaussian (LQG) and MPC formulations to provide robustness against various modeling uncertainties and external disturbances. The effectiveness of the proposed feedback controllers in regulating the current density profile in NSTX-U is demonstrated in closed-loop nonlinear simulations. Moreover, the optimal feedback control algorithm has been implemented successfully in closed-loop control simulations within TRANSP through the recently developed Expert routine. (Abstract shortened by ProQuest.).

  16. The anonymity paradox in patient engagement: reputation, risk and web-based public feedback.

    Science.gov (United States)

    Speed, Ewen; Davison, Charlie; Gunnell, Caroline

    2016-06-01

    The UK National Health Service (NHS) has long espoused patient and public engagement. Recent years have seen increasing use of internet-based methods of collecting feedback about patient experience and public and staff views about NHS services and priorities. Often hailed as a means of facilitating participative democratic patient engagement, these processes raise a number of complex issues. A key aspect of it is the opportunity for comment to be made anonymously. Our research reveals an anonymity paradox whereby patients clearly demonstrate a perception that anonymity is a prerequisite for effective use of these feedback processes, whereas professionals demonstrate a perception that patient anonymity is a barrier to effective use. The risks of anonymity are constructed very differently by patients and professionals. Patient concerns around anonymity were not motivated by a general concern about a loss of privacy, but more that a positive identification might compromise future care. For professionals, concerns were voiced more around risks of reputational damage for specific practitioners or practices (in that anyone could say anything) and also that this anonymous feedback was available publicly and that it might go against the medical opinion of the professional. These concerns pointed to important differences in perceptions of patient and professional vulnerability. In the qualitative analysis that follows the key finding was that while anonymity makes service users feel less vulnerable, it can have the opposite effect on managers and clinical staff. This raises important implications for the use and utility of internet-based methods of collecting patient feedback.

  17. A sensory feedback system for prosthetic hand based on evoked tactile sensation.

    Science.gov (United States)

    Liu, X X; Chai, G H; Qu, H E; Lan, N

    2015-01-01

    The lack of reliable sensory feedback has been one of the barriers in prosthetic hand development. Restoring sensory function from prosthetic hand to amputee remains a great challenge to neural engineering. In this paper, we present the development of a sensory feedback system based on the phenomenon of evoked tactile sensation (ETS) at the stump skin of residual limb induced by transcutaneous electrical nerve stimulation (TENS). The system could map a dynamic pattern of stimuli to an electrode placed on the corresponding projected finger areas on the stump skin. A pressure transducer placed at the tip of prosthetic fingers was used to sense contact pressure, and a high performance DSP processor sampled pressure signals, and calculated the amplitude of feedback stimulation in real-time. Biphasic and charge-balanced current pulses with amplitude modulation generated by a multi-channel laboratory stimulator were delivered to activate sensory nerves beneath the skin. We tested this sensory feedback system in amputee subjects. Preliminary results showed that the subjects could perceive different levels of pressure at the tip of prosthetic finger through evoked tactile sensation (ETS) with distinct grades and modalities. We demonstrated the feasibility to restore the perceptual sensation from prosthetic fingers to amputee based on the phenomenon of evoked tactile sensation (ETS) with TENS.

  18. The Model of the IT Impact Treated as Feedback in a Production Environment Based on a Cybernetic Model

    Directory of Open Access Journals (Sweden)

    Cornelia NOVAC-UDUDEC

    2011-11-01

    Full Text Available This paper presents an approach on the assessment of the impact that Information Technology has in an based- knowledge economy. In order to achieve this goal, we proposed the use of feedback model from the production environment, considered as a cybernetic system. The impact of the IT is treated similarly to the technological and behavioral relationships between the main effects of feedbacks. We also studied different effects that feedback produces as an IT impact.

  19. Output feedback suboptimal disturbance rejection for linear systems : internal - model principle method%线性系统的输出反馈次优扰动抑制:内模原理方法

    Institute of Scientific and Technical Information of China (English)

    雷靖

    2012-01-01

    The paper considered the output feedback disturbance rejection problem based on internal - model principle for linear systems. According to the disturbance dynamics, the internal model was constructed. The optimal disturbance rejection problem was transformed into an equivalent optimal regulation problem for the augmented system. Then, a reduced - order state observer was constructed to reconstruct the unmeasurable state variables from the output feedback. The suboptimal control law was derived from series matrix differential equations or matrix equations, in which the disturbance was eliminated by the internal -model compensator. Finally, a simplified offshore platform system was applied for simulation example. Comparing with the feedforward and feedback optimal disturbance rejection control law, the designed controller was validated to be able to reject disturbance without steadystate error.%运用内模原理研究线性系统的输出反馈扰动抑制问题.首先根据扰动的动态特性构造内模系统,将最优扰动抑制问题转化为等价的最优调节问题.然后通过构造降维状态观测器重构输出反馈中测量不到的部分状态变量;通过求解一组矩阵微分方程或矩阵方程得到次优控制律,利用控制律中的内模补偿项与外部扰动进行对消.最后采用海洋平台简化模型作仿真示例,将所设计的扰动抑制控制器与前馈反馈最优扰动抑制控制器作比较,证明所设计的控制器能够实现无静差的扰动抑制.

  20. Robust H∞ Controller Design for Uncertain Neutral Systems via Dynamic Observer Based Output Feedback

    Institute of Scientific and Technical Information of China (English)

    Fatima El Haoussi; El (H)oussaine Tissir

    2009-01-01

    In this paper, the dynamic observer-based controller design for a class of neutral systems with H∞ control is considered. An observer-based output feedback is derived for systems with polytopic parameter uncertainties. This controller assures delay-dependent stabilization and H∞ norm bound attenuation from the disturbance input to the controllcd output. Numerical examples are provided for illustration and comparison of the proposed conditions.

  1. Multivariable Feedback Control of Nuclear Reactors

    Directory of Open Access Journals (Sweden)

    Rune Moen

    1982-07-01

    Full Text Available Multivariable feedback control has been adapted for optimal control of the spatial power distribution in nuclear reactor cores. Two design techniques, based on the theory of automatic control, were developed: the State Variable Feedback (SVF is an application of the linear optimal control theory, and the Multivariable Frequency Response (MFR is based on a generalization of the traditional frequency response approach to control system design.

  2. Feedback-Based Resource Allocation in MapReduce-Based Systems

    Directory of Open Access Journals (Sweden)

    Bunjamin Memishi

    2016-01-01

    Full Text Available Containers are considered an optimized fine-grain alternative to virtual machines in cloud-based systems. Some of the approaches which have adopted the use of containers are the MapReduce frameworks. This paper makes an analysis of the use of containers in MapReduce-based systems, concluding that the resource utilization of these systems in terms of containers is suboptimal. In order to solve this, the paper describes AdaptCont, a proposal for optimizing the containers allocation in MapReduce systems. AdaptCont is based on the foundations of feedback systems. Two different selection approaches, Dynamic AdaptCont and Pool AdaptCont, are defined. Whereas Dynamic AdaptCont calculates the exact amount of resources per each container, Pool AdaptCont chooses a predefined container from a pool of available configurations. AdaptCont is evaluated for a particular case, the application master container of Hadoop YARN. As we can see in the evaluation, AdaptCont behaves much better than the default resource allocation mechanism of Hadoop YARN.

  3. Industrially-Situated Project-Based Learning: A Study of Feedback and Diffusion

    Science.gov (United States)

    Gilbuena, Debra M.

    The Virtual Chemical Vapor Deposition (CVD) Process Development Project provides the context for the two areas of the research presented in this dissertation. The first area, generally referred to as feedback in this dissertation, focuses on student learning and the interactions of students and instructors that take place in the project, specifically focused on characterizing feedback and determining the influence of feedback as student teams progress towards completing the project. The characteristics of feedback found in this project are presented within a situative perspective using the analytical framework of episodes. The characteristics include: a list and categorization of episode themes, the structure and flow of episodes during the coaching session, the sub-structure present within individual episodes, and the types of feedback present. This dissertation shows how these characteristics frame participation in a community of practice and can be used as tools to scaffold instructor feedback in project-based learning. Episodes analysis is also used to investigate how feedback on professional skills can help to enculturate students into a community of practice and influence their fluency with professional skills and engagement in more technical activities. The second area examines the spread of this innovative project from its home institution to other institutions. In this area an analysis of the spread of the Virtual CVD Process Development Project in the high school setting is presented. The project was found to provide versatility for instructors and afford student learning in the areas of motivation, cognition, and epistemological beliefs. These two areas inform each other. As the project is assessed at different institutions, it is continually improved and the sensitivity of different aspects of the project is explored, e.g., the aspects of the project that are crucial to maintain effectiveness are identified. One of these aspects is the feedback that

  4. Fraction Dynamic-Surface-Based Neuroadaptive Finite-Time Containment Control of Multiagent Systems in Nonaffine Pure-Feedback Form.

    Science.gov (United States)

    Wang, Yujuan; Song, Yongduan

    2017-03-01

    In this paper, the problem of containment control of networked multiagent systems is considered with special emphasis on finite-time convergence. A distributed neural adaptive control scheme for containment is developed, which, different from the current state of the art, is able to achieve dynamic containment in finite time with sufficient accuracy despite unknown nonaffine dynamics and mismatched uncertainties. Such a finite-time feature, highly desirable in practice, is made possible by the fraction dynamic surface control design technique based on the concept of virtual fraction filter. In the proposed containment protocol, only the local information from the neighbor followers and the local position information from the neighbor leaders are required. Furthermore, since the available information utilized is local and is embedded into the control scheme through fraction power feedback, rather than direct linear or regular nonlinear feedback, the resultant control scheme is truly distributed. In addition, although mismatched uncertainties and external disturbances are involved, only one single generalized neural parameter needs to be updated in the control scheme, making its design and implementation straightforward and inexpensive. The effectiveness of the developed method is also confirmed by numerical simulation.

  5. Controlling the quantum-memory-assisted entropic uncertainty relation by quantum-jump-based feedback control in dissipative environments

    Science.gov (United States)

    Yu, Min; Fang, Mao-Fa

    2017-09-01

    The dynamic properties of the quantum-memory-assisted entropic uncertainty relation for a system comprised of a qubit to be measured and a memory qubit are investigated. We explore the behaviors of the entropic uncertainty and its lower bound in three different cases: Only one of the two qubits interacts with an external environment and subjects to quantum-jump-based feedback control, or both of the two qubits independently experience their own environments and local quantum-jump-based feedback control. Our results reveal that the quantum-jump-based feedback control with an appropriate feedback parameter can reduce the entropic uncertainty and its lower bound, and for the three different scenarios, the reduction in the uncertainty relates to different physical quantities. Besides, we find out that the quantum-jump-based feedback control not only can remarkably decrease the entropic uncertainty, but also can make the uncertainty reach its lower bound where the dynamical map becomes unital.

  6. Profile-based short linear protein motif discovery

    Science.gov (United States)

    2012-01-01

    Background Short linear protein motifs are attracting increasing attention as functionally independent sites, typically 3–10 amino acids in length that are enriched in disordered regions of proteins. Multiple methods have recently been proposed to discover over-represented motifs within a set of proteins based on simple regular expressions. Here, we extend these approaches to profile-based methods, which provide a richer motif representation. Results The profile motif discovery method MEME performed relatively poorly for motifs in disordered regions of proteins. However, when we applied evolutionary weighting to account for redundancy amongst homologous proteins, and masked out poorly conserved regions of disordered proteins, the performance of MEME is equivalent to that of regular expression methods. However, the two approaches returned different subsets within both a benchmark dataset, and a more realistic discovery dataset. Conclusions Profile-based motif discovery methods complement regular expression based methods. Whilst profile-based methods are computationally more intensive, they are likely to discover motifs currently overlooked by regular expression methods. PMID:22607209

  7. Profile-based short linear protein motif discovery

    Directory of Open Access Journals (Sweden)

    Haslam Niall J

    2012-05-01

    Full Text Available Abstract Background Short linear protein motifs are attracting increasing attention as functionally independent sites, typically 3–10 amino acids in length that are enriched in disordered regions of proteins. Multiple methods have recently been proposed to discover over-represented motifs within a set of proteins based on simple regular expressions. Here, we extend these approaches to profile-based methods, which provide a richer motif representation. Results The profile motif discovery method MEME performed relatively poorly for motifs in disordered regions of proteins. However, when we applied evolutionary weighting to account for redundancy amongst homologous proteins, and masked out poorly conserved regions of disordered proteins, the performance of MEME is equivalent to that of regular expression methods. However, the two approaches returned different subsets within both a benchmark dataset, and a more realistic discovery dataset. Conclusions Profile-based motif discovery methods complement regular expression based methods. Whilst profile-based methods are computationally more intensive, they are likely to discover motifs currently overlooked by regular expression methods.

  8. Testing the transtheoretical model for fruit intake: comparing web-based tailored stage-matched and stage-mismatched feedback.

    Science.gov (United States)

    de Vet, Emely; de Nooijer, Jascha; de Vries, Nanne K; Brug, Johannes

    2008-04-01

    A match-mismatch test was conducted to test the transtheoretical model applied to fruit intake. Precontemplators and contemplators were randomly assigned to receive a web-based individualized precontemplation feedback (PCF), contemplation feedback (CF) or action feedback (AF) letter promoting fruit intake. Immediately and 1 week after reading this letter, post-test measures were obtained. Fruit intake increased significantly between pre- and post-test in contemplators, but not in precontemplators. No differences between the feedback conditions were found in fruit intake, stage progression, use or credibility of the feedback in precontemplators and contemplators. In precontemplators, also no differences between the conditions were found in personal relevance of the feedback. Contemplators, however, rated AF as more personally relevant than PCF or CF. To conclude, the present study failed to show superiority of stage-matched information in the promotion of fruit intake.

  9. Max-plus-linear model-based predictive control for constrained hybrid systems:linear programming solution

    Institute of Scientific and Technical Information of China (English)

    Yuanyuan ZOU; Shaoyuan LI

    2007-01-01

    In this paper,a linear programming method is proposed to solve model predictive control for a class of hybrid systems.Firstly,using the(max,+)algebra,a typical subclass of hybrid systems called max-plus-linear(MPL)systems is obtained.And then,model predictive control(MPC)framework is extended to MPL systems.In general,the nonlinear optimization approach or extended linear complementarity problem(ELCP)were applied to solve the MPL-MPC optimization problem.A new optimization method based on canonical forms for max-min-plus-scaling(MMPS)functions (using the operations maximization,minimization,addition and scalar multiplication)with linear constraints on the inputs is presented.The proposed approach consists in solving several linear programming problems and is more efficient than nonlinear optimization.The validity of the algorithm is illustrated by an example.

  10. Types of Feedback in Competency-Based Predoctoral Orthodontics: Effects on Students' Attitudes and Confidence.

    Science.gov (United States)

    Lipp, Mitchell J; Cho, Kiyoung; Kim, Han Suk

    2017-05-01

    Feedback can exert a powerful influence on learning and achievement although its effect varies. The aim of this study was to investigate the effects of three types of feedback on dental students' attitudes and confidence in a competency-based course in predoctoral orthodontics at New York University College of Dentistry. In 2013-14, all 253 third-year students in a course using test-enhanced instructional methods received written feedback on formative assessments. The type of feedback varied across three groups: pass/fail grades (PF) N=77, emoticons (EM) N=90, or written comments (WC) N=86. At the end of the course, students completed surveys that included four statements addressing their attitudes toward course instruction and confidence in their abilities. The survey response rate ranged from 75% to 100% among groups. The lowest response rate (75%) was in the PF group. In attitudes toward course instruction and confidence in their abilities, the WC group trended to more positive responses than the other groups, while the PF group trended to negative responses. On two of the four statements, the trend for the WC group was significant (95% CI). In both statements concerning attitudes toward instruction, the PF group trended to negative responses that were significant (95% CI). These results support the effectiveness of descriptive written comments over pass/fail grades or emoticons in improving dental students' confidence in their abilities and their attitudes toward instruction.

  11. Automated numerical simulation of biological pattern formation based on visual feedback simulation framework

    Science.gov (United States)

    Sun, Mingzhu; Xu, Hui; Zeng, Xingjuan; Zhao, Xin

    2017-01-01

    There are various fantastic biological phenomena in biological pattern formation. Mathematical modeling using reaction-diffusion partial differential equation systems is employed to study the mechanism of pattern formation. However, model parameter selection is both difficult and time consuming. In this paper, a visual feedback simulation framework is proposed to calculate the parameters of a mathematical model automatically based on the basic principle of feedback control. In the simulation framework, the simulation results are visualized, and the image features are extracted as the system feedback. Then, the unknown model parameters are obtained by comparing the image features of the simulation image and the target biological pattern. Considering two typical applications, the visual feedback simulation framework is applied to fulfill pattern formation simulations for vascular mesenchymal cells and lung development. In the simulation framework, the spot, stripe, labyrinthine patterns of vascular mesenchymal cells, the normal branching pattern and the branching pattern lacking side branching for lung branching are obtained in a finite number of iterations. The simulation results indicate that it is easy to achieve the simulation targets, especially when the simulation patterns are sensitive to the model parameters. Moreover, this simulation framework can expand to other types of biological pattern formation. PMID:28225811

  12. Nanoporous Carbide-Derived Carbon Material-Based Linear Actuators

    Directory of Open Access Journals (Sweden)

    Janno Torop

    2009-12-01

    Full Text Available Devices using electroactive polymer-supported carbon material can be exploited as alternatives to conventional electromechanical actuators in applications where electromechanical actuators have some serious deficiencies. One of the numerous examples is precise microactuators. In this paper, we show for first time the dilatometric effect in nanocomposite material actuators containing carbide-derived carbon (CDC and polytetrafluoroetylene polymer (PTFE. Transducers based on high surface area carbide-derived carbon electrode materials are suitable for short range displacement applications, because of the proportional actuation response to the charge inserted, and high Coulombic efficiency due to the EDL capacitance. The material is capable of developing stresses in the range of tens of N cm-2. The area of an actuator can be dozens of cm2, which means that forces above 100 N are achievable. The actuation mechanism is based on the interactions between the high-surface carbon and the ions of the electrolyte. Electrochemical evaluations of the four different actuators with linear (longitudinal action response are described. The actuator electrodes were made from two types of nanoporous TiC-derived carbons with surface area (SA of 1150 m2 g-1 and 1470 m2 g-1, respectively. Two kinds of electrolytes were used in actuators: 1.0 M tetraethylammonium tetrafluoroborate (TEABF4 solution in propylene carbonate and pure ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMITf. It was found that CDC based actuators exhibit a linear movement of about 1% in the voltage range of 0.8 V to 3.0 V at DC. The actuators with EMITf electrolyte had about 70% larger movement compared to the specimen with TEABF4 electrolyte.

  13. Fast Programming Algorithm to Find Non-Linear Feedback Shift Register%快速寻找非线性反馈移位寄存器的编程算法

    Institute of Scientific and Technical Information of China (English)

    叶炜晨; 陈克非

    2014-01-01

    Non-linear feedback shift register (NLFSR) is a common device to generate pseudo-random sequences in stream cipher. However, there is still no effective mathematical algorithm to find NLFSRs for a given period or output sequence. This paper provides a quick method to find NLFSRs. This method is a programming algorithm based on compute unified device architecture (CUDA) and parallel computing, and can quickly find NLFSRs for the given period or output sequence. This method has very good performance on both simple and complex NLFSRs. With this new method, people can easily get a large amount of experimental data about NLFSRs. It will be a great help for the future research on the mathematical algorithm to find NLFSRs.%在流密码中,非线性反馈移位寄存器(non-linear feedback shift register,NLFSR)是一种常用的安全性较高的伪随机序列生成器。目前仍然没有一种普遍有效的数学算法,能够根据给定的序列或者序列周期,直接推导出NLFSR。提出了一种快速寻找NLFSR的编程算法。该算法基于统一计算架构(compute unified device architecture,CUDA)和并行计算来实现,计算速度快,尤其适用于处理高次数的复杂NLFSR。并且该算法可以快速大规模地计算出NLFSR,为未来研究寻找NLFSR的数学算法提供了大量的实验数据。

  14. Model Based Adaptive Piecewise Linear Controller for Complicated Control Systems

    Directory of Open Access Journals (Sweden)

    Tain-Sou Tsay

    2014-01-01

    Full Text Available A model based adaptive piecewise linear control scheme for industry processes with specifications on peak overshoots and rise times is proposed. It is a gain stabilized control technique. Large gain is used for large tracking error to get fast response. Small gain is used between large and small tracking error for good performance. Large gain is used again for small tracking error to cope with large disturbance. Parameters of the three-segment piecewise linear controller are found by an automatic regulating time series which is function of output characteristics of the plant and reference model. The time series will be converged to steady values after the time response of the considered system matching that of the reference model. The proposed control scheme is applied to four numerical examples which have been compensated by PID controllers. Parameters of PID controllers are found by optimization method. It gives an almost command independent response and gives significant improvements for response time and performance.

  15. ASYMBOOST-BASED FISHER LINEAR CLASSIFIER FOR FACE RECOGNITION

    Institute of Scientific and Technical Information of China (English)

    Wang Xianji; Ye Xueyi; Li Bin; Li Xin; Zhuang Zhenquan

    2008-01-01

    When using AdaBoost to select discriminant features from some feature space (e.g. Gabor feature space) for face recognition, cascade structure is usually adopted to leverage the asymmetry in the distribution of positive and negative samples. Each node in the cascade structure is a classifier trained by AdaBoost with an asymmetric learning goal of high recognition rate but only moderate low false positive rate. One limitation of AdaBoost arises in the context of skewed example distribution and cascade classifiers: AdaBoost minimizes the classification error, which is not guaranteed to achieve the asymmetric node learning goal. In this paper, we propose to use the asymmetric AdaBoost (Asym-Boost) as a mechanism to address the asymmetric node learning goal. Moreover, the two parts of the selecting features and forming ensemble classifiers are decoupled, both of which occur simultaneously in AsymBoost and AdaBoost. Fisher Linear Discriminant Analysis (FLDA) is used on the selected features to learn a linear discriminant function that maximizes the separability of data among the different classes, which we think can improve the recognition performance. The proposed algorithm is dem onstrated with face recognition using a Gabor based representation on the FERET database. Experimental results show that the proposed algorithm yields better recognition performance than AdaBoost itself.

  16. Distance Transform Based Enhancement for Linear Interpolated Images

    Institute of Scientific and Technical Information of China (English)

    唐莉萍; 曾培峰

    2003-01-01

    An approach of distance map based image enhancement (DMIE) is proposed. It is applied to conventional interpolations to get sharp images. Edge detection is performed after images are interpolated by linear interpolations. To meet the two conditions set for DMIE, i. e., no abrupt changes and no overboosting, different boosting rate should be used in adjusting pixel intensities. When the boosting rate is determined by using the distance from enhanced pixels to nearest edges, edge-oriented image enhancement is obtained. By using Erosion technique, the range for pixel intensity adjustment is set. Over-enhancement is avoided by limiting the pixel intensities in enhancement within the range.A unified linear-time algorithm for distance transform is adopted to deal with the calculation of Euclidean distance of the images. Its computation complexity is O (N2 ). After the preparation, i. e.,distance transforming and erosion, the images get more and more sharpened while no over-boosting occurs by repeating the enhancement procedure. The simplicity of the enhancement operation makes DMIE suitable for enhancement rate adjusting.

  17. Manifold-Based Reinforcement Learning via Locally Linear Reconstruction.

    Science.gov (United States)

    Xu, Xin; Huang, Zhenhua; Zuo, Lei; He, Haibo

    2017-04-01

    Feature representation is critical not only for pattern recognition tasks but also for reinforcement learning (RL) methods to solve learning control problems under uncertainties. In this paper, a manifold-based RL approach using the principle of locally linear reconstruction (LLR) is proposed for Markov decision processes with large or continuous state spaces. In the proposed approach, an LLR-based feature learning scheme is developed for value function approximation in RL, where a set of smooth feature vectors is generated by preserving the local approximation properties of neighboring points in the original state space. By using the proposed feature learning scheme, an LLR-based approximate policy iteration (API) algorithm is designed for learning control problems with large or continuous state spaces. The relationship between the value approximation error of a new data point and the estimated values of its nearest neighbors is analyzed. In order to compare different feature representation and learning approaches for RL, a comprehensive simulation and experimental study was conducted on three benchmark learning control problems. It is illustrated that under a wide range of parameter settings, the LLR-based API algorithm can obtain better learning control performance than the previous API methods with different feature representation schemes.

  18. Quantum repeaters based on atomic ensembles and linear optics

    Science.gov (United States)

    Sangouard, Nicolas; Simon, Christoph; de Riedmatten, Hugues; Gisin, Nicolas

    2011-01-01

    The distribution of quantum states over long distances is limited by photon loss. Straightforward amplification as in classical telecommunications is not an option in quantum communication because of the no-cloning theorem. This problem could be overcome by implementing quantum repeater protocols, which create long-distance entanglement from shorter-distance entanglement via entanglement swapping. Such protocols require the capacity to create entanglement in a heralded fashion, to store it in quantum memories, and to swap it. One attractive general strategy for realizing quantum repeaters is based on the use of atomic ensembles as quantum memories, in combination with linear optical techniques and photon counting to perform all required operations. Here the theoretical and experimental status quo of this very active field are reviewed. The potentials of different approaches are compared quantitatively, with a focus on the most immediate goal of outperforming the direct transmission of photons.

  19. Quantum repeaters based on atomic ensembles and linear optics

    CERN Document Server

    Sangouard, Nicolas; de Riedmatten, Hugues; Gisin, Nicolas

    2009-01-01

    The distribution of quantum states over long distances is limited by photon loss. Straightforward amplification as in classical telecommunications is not an option in quantum communication because of the no-cloning theorem. This problem could be overcome by implementing quantum repeater protocols, which create long-distance entanglement from shorter-distance entanglement via entanglement swapping. Such protocols require the capacity to create entanglement in a heralded fashion, to store it in quantum memories, and to swap it. One attractive general strategy for realizing quantum repeaters is based on the use of atomic ensembles as quantum memories, in combination with linear optical techniques and photon counting to perform all required operations. Here we review the theoretical and experimental status quo of this very active field. We compare the potential of different approaches quantitatively, with a focus on the most immediate goal of outperforming the direct transmission of photons.

  20. Cluster-Based Distributed Algorithms for Very Large Linear Equations

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In many applications such as computational fluid dynamics and weather prediction, as well as image processing and state of Markov chain etc., the grade of matrix n is often very large, and any serial algorithm cannot solve the problems. A distributed cluster-based solution for very large linear equations is discussed, it includes the definitions of notations, partition of matrix, communication mechanism, and a master-slaver algorithm etc., the computing cost is O(n3/N), the memory cost is O(n2/N), the I/O cost is O(n2/N), and the communication cost is O(Nn), here, N is the number of computing nodes or processes. Some tests show that the solution could solve the double type of matrix under 106×106 effectively.

  1. Measurement-based noiseless linear amplification for quantum communication

    Science.gov (United States)

    Chrzanowski, H. M.; Walk, N.; Haw, J. Y.; Thearle, O.; Assad, S. M.; Janousek, J.; Hosseini, S.; Ralph, T. C.; Symul, T.; Lam, P. K.

    2014-11-01

    Entanglement distillation is an indispensable ingredient in extended quantum communication networks. Distillation protocols are necessarily non-deterministic and require non-trivial experimental techniques such as noiseless amplification. We show that noiseless amplification could be achieved by performing a post-selective filtering of measurement outcomes. We termed this protocol measurement-based noiseless linear amplification (MBNLA). We apply this protocol to entanglement that suffers transmission loss of up to the equivalent of 100km of optical fibre and show that it is capable of distilling entanglement to a level stronger than that achievable by transmitting a maximally entangled state through the same channel. We also provide a proof-of-principle demonstration of secret key extraction from an otherwise insecure regime via MBNLA. Compared to its physical counterpart, MBNLA not only is easier in term of implementation, but also allows one to achieve near optimal probability of success.

  2. Exploring the Impact of Role-Playing on Peer Feedback in an Online Case-Based Learning Activity

    Science.gov (United States)

    Ching, Yu-Hui

    2014-01-01

    This study explored the impact of role-playing on the quality of peer feedback and learners' perception of this strategy in a case-based learning activity with VoiceThread in an online course. The findings revealed potential positive impact of role-playing on learners' generation of constructive feedback as role-playing was associated…

  3. Effects of remote feedback in home-based physical activity interventions for older adults : A systematic review

    NARCIS (Netherlands)

    Geraedts, Hilde; Zijlstra, Agnes; Bulstra, Sjoerd K.; Stevens, Martin; Zijlstra, Wiebren

    2013-01-01

    Objective: To evaluate the literature on effectiveness of remote feedback on physical activity and capacity in home-based physical activity interventions for older adults with or without medical conditions. In addition, the effect of remote feedback on adherence was inventoried. Methods: A systemati

  4. Loosen Couple Workflow Mode of Lean Operator Improvement Based on Positive Feedback

    Directory of Open Access Journals (Sweden)

    Yao Li

    2013-04-01

    Full Text Available In order to promote the core competitive power for telecom operating enterprises to face market fine operation, this article compares the ECTA mode (Extension Case Transmission Mode and the LCA mode (Loosen Couple Mode, both of which are promoted by WfMC. By comparing these two modes, the suitable situations for these two modes are determined. We also carry out empirical analysis based on the customization mode of mobile phones between China telecom and mobile phone manufacturers and to expound the ascension effect of mechanism based on the agile telecom loose coupling workflow with positive feedback to the telecom enterprises. Finally, on the basis of positive feedback system, the task complexity and information transparency of LCA mode are improved, so that the semantics of public flow mode is kept unchanged and the sub workflow is optimized when modifying the sub workflow.

  5. FEEDBACK LINEARISATION APPLIED ON A HYDRAULIC

    DEFF Research Database (Denmark)

    Andersen, Torben Ole; Hansen, Michael Rygaard; Pedersen, Henrik C.;

    2005-01-01

    Generally most hydraulic systems are intrensically non-linear, why applying linear control techniques typically results in conservatively dimensioned controllers to obtain stable performance. Non-linear control techniques have the potential of overcoming these problems, and in this paper the focus...... is on developing and applying several different feedback linearisation (FL) controllers to the individual servo actuators in a hydraulically driven servo robot to evaluate and compare their possiblities and limitations. This is done based on both simulation and experimental results....

  6. Second Order Sliding Mode-Based Output Feedback Tracking Control for Uncertain Robot Manipulators

    OpenAIRE

    Van, Mien; Hee-Jun Kang; Young-Soo Suh

    2013-01-01

    In this paper, a robust output feedback tracking control scheme for motion control of uncertain robot manipulators without joint velocity measurement based on a second-order sliding mode (SOSM) observer is presented. Two second‐order sliding mode observers with finite time convergence are developed for velocity estimation and uncertainty identification, respectively. The first SOSM observer is used to estimate the state vector in finite time without filtration. However, for uncertainty identi...

  7. Electrically tunable terahertz quantum cascade lasers based on a two-sections interdigitated distributed feedback cavity

    Energy Technology Data Exchange (ETDEWEB)

    Turčinková, Dana; Scalari, Giacomo; Beck, Mattias; Faist, Jérôme [ETH Zurich, Institute for Quantum Electronics, Auguste-Piccard-Hof 1, 8093 Zurich (Switzerland); Amanti, Maria Ines [ETH Zurich, Institute for Quantum Electronics, Auguste-Piccard-Hof 1, 8093 Zurich (Switzerland); Univ. Paris Diderot, Lab. Matererk iaux et Phenomenes Quantiques, F-75205 Paris (France)

    2015-03-30

    The continuous electrical tuning of a single-mode terahertz quantum cascade laser operating at a frequency of 3 THz is demonstrated. The devices are based on a two-section interdigitated third-order distributed feedback cavity. The lasers can be tuned of about 4 GHz at a constant optical output power of 0.7 mW with a good far-field pattern.

  8. Chaos control in delayed chaotic systems via sliding mode based delayed feedback

    Energy Technology Data Exchange (ETDEWEB)

    Vasegh, Nastaran [Faculty of Electrical Engineering, K.N. Toosi University of Technology, Seyed Khandan Bridge, Shariati St. 16314, P.O. Box 16315-1355, Tehran (Iran, Islamic Republic of)], E-mail: vasegh@eetd.kntu.ac.ir; Sedigh, Ali Khaki [Faculty of Electrical Engineering, K.N. Toosi University of Technology, Seyed Khandan Bridge, Shariati St. 16314, P.O. Box 16315-1355, Tehran (Iran, Islamic Republic of)

    2009-04-15

    This paper investigates chaos control for scalar delayed chaotic systems using sliding mode control strategy. Sliding surface design is based on delayed feedback controller. It is shown that the proposed controller can achieve stability for an arbitrary unstable fixed point (UPF) or unstable periodic orbit (UPO) with arbitrary period. The chaotic system used in this study to illustrate the theoretical concepts is the well known Mackey-Glass model. Simulation results show the effectiveness of the designed nonlinear sliding mode controller.

  9. Voltage and Current Regulators Design of Power Converters in Islanded Microgrids based on State Feedback Decoupling

    DEFF Research Database (Denmark)

    Federico, de Bosio; de Sousa Ribeiro, Luiz Antonio; Freijedo Fernandez, Francisco Daniel

    2016-01-01

    In stand-alone microgrids based on voltage source inverters state feedback coupling between the capacitor voltage and inductor current degrades significantly the dynamics performance of voltage and current regulators. The decoupling of the controlled states is proposed, considering the limitations...... introduced by system delays. Moreover, a proportional resonant voltage controller is designed according to Nyquist criterion taking into account application requirements. Experimental tests performed in compliance with the UPS standards verify the theoretical analysis....

  10. Neural feedback linearization adaptive control for affine nonlinear systems based on neural network estimator

    Directory of Open Access Journals (Sweden)

    Bahita Mohamed

    2011-01-01

    Full Text Available In this work, we introduce an adaptive neural network controller for a class of nonlinear systems. The approach uses two Radial Basis Functions, RBF networks. The first RBF network is used to approximate the ideal control law which cannot be implemented since the dynamics of the system are unknown. The second RBF network is used for on-line estimating the control gain which is a nonlinear and unknown function of the states. The updating laws for the combined estimator and controller are derived through Lyapunov analysis. Asymptotic stability is established with the tracking errors converging to a neighborhood of the origin. Finally, the proposed method is applied to control and stabilize the inverted pendulum system.

  11. App-based attention training: Incorporating older adults' feedback to facilitate home-based use.

    Science.gov (United States)

    Hill, Nikki L; Mogle, Jacqueline; Wion, Rachel; Kitt-Lewis, Erin; Hannan, John; Dick, Robert; McDermott, Caroline

    2017-07-28

    Technology-based attention training programs have demonstrated promise in improving cognitive functioning in older adults. The purpose of this study was to evaluate the usability and acceptability of a modified version of a mobile attention training application. A descriptive, mixed-methods design was used to capture older adults' feedback on the usability and acceptability of the modified attention training application. A convenience sample of older adults (n = 12) participated in three study visits and a one-week testing period of the modified attention training application in their homes. Descriptive statistics were calculated for all quantitative data, and an iterative content analysis was used to characterise participant responses. On average, participants rated the modified attention training application more positively than negatively in terms of usability, interest, enjoyment and satisfaction. The qualitative analyses revealed positive aspects of using the app including working through challenges, perceived benefit and helpfulness of instructions. The modified attention training application was usable by and acceptable to the majority of older adults in our sample who had varying degrees of experience with mobile technology. Future development should specifically consider personal characteristics as well as individual preferences to maximise the potential of the modified attention training application. This technology may be helpful for providing memory improvement interventions to older persons with cognitive impairment who do not have access to memory clinics. © 2017 John Wiley & Sons Ltd.

  12. Real-time feedback based control of cardiac restitution using optical mapping.

    Science.gov (United States)

    Kulkarni, Kanchan; Tolkacheva, Elena G

    2015-01-01

    Cardiac restitution is the shortening of the action potential duration with an increase in the heart rate. A shorter action potential duration enables a longer diastolic interval which ensures that the heart gets adequate time to refill with blood. At higher rates however, restitution becomes steep and thus, can lead to unstable electrical activity (alternans) in the heart, leading to fatal cardiac rhythms. It has been proposed that maintaining a shallow slope of cardiac restitution could have potentially anti-arrhythmic effects. Previous studies involved the control of action potential duration (APD) or diastolic interval (DI) in isolated tissue samples based on the feedback from single microelectrode recordings. This limited the spatial resolution of the feedback system. Here, we aimed to develop a real time feedback control system that enabled the detection of APDs from various single pixels based on optical mapping recordings. Stimuli were applied after a predefined fixed DI after detection of an APD. We validated our algorithm using optical mapping movies from an ex-vivo rabbit heart. Thus, we provide an optical mapping based approach for the control of cardiac restitution and a potential means to validate its anti-arrhythmic effects.

  13. More confident trauma resuscitation team leaders: a novel simulation-based training curriculum utilizing video feedback

    Directory of Open Access Journals (Sweden)

    John L. Falcone

    2013-02-01

    Full Text Available There are deficiencies in trauma leader performance. Simulation training and video-based feedback can lead to durable changes in behavior. A trauma resuscitation team leader training curriculum was developed. The curriculum consisted of eight simulated trauma scenarios with a mix of acuities and injury patterns using patient simulators. Other team members included a surgeon, an anesthesiologist, a chief resident, a trauma nurse, a medical student, and presenting emergency medicine staff. Each scenario was followed by video-based feedback. Attitudes regarding this curriculum were evaluated before and after the intervention with Likert-based surveys. Eight residents completed the curriculum. On a seven-point Likert scale, the median overall curriculum rating, the video discussion quality, the plan to apply leadership skills, and the plan to apply learned knowledge and behaviors was 7/7. A Wilcoxon Sign-Rank test showed improved confidence for leading Level 1 trauma resuscitations, improved beliefs in adequate training, and improved attitudes regarding team leader training (P<0.05. There was reduced nervousness of being the team leader (P=0.048. Qualitative analyses showed that the learners valued the feedback process and scenario realism. This pilot curriculum was well-received by trauma residents and offers insight into meta-cognition of trauma team leaders.

  14. Stochastic Optimized Relevance Feedback Particle Swarm Optimization for Content Based Image Retrieval

    Directory of Open Access Journals (Sweden)

    Muhammad Imran

    2014-01-01

    Full Text Available One of the major challenges for the CBIR is to bridge the gap between low level features and high level semantics according to the need of the user. To overcome this gap, relevance feedback (RF coupled with support vector machine (SVM has been applied successfully. However, when the feedback sample is small, the performance of the SVM based RF is often poor. To improve the performance of RF, this paper has proposed a new technique, namely, PSO-SVM-RF, which combines SVM based RF with particle swarm optimization (PSO. The aims of this proposed technique are to enhance the performance of SVM based RF and also to minimize the user interaction with the system by minimizing the RF number. The PSO-SVM-RF was tested on the coral photo gallery containing 10908 images. The results obtained from the experiments showed that the proposed PSO-SVM-RF achieved 100% accuracy in 8 feedback iterations for top 10 retrievals and 80% accuracy in 6 iterations for 100 top retrievals. This implies that with PSO-SVM-RF technique high accuracy rate is achieved at a small number of iterations.

  15. Linear Algebra for Computing Gröbner Bases of Linear Recursive Multidimensional Sequences

    OpenAIRE

    2016-01-01

    International audience; Sakata generalized the Berlekamp -- Massey algorithm to $n$ dimensions in~1988. The Berlekamp -- Massey -- Sakata (BMS)algorithm can be used for finding a Gröbner basis of a $0$-dimensionalideal of relations verified by a table. We investigate this problem usinglinear algebra techniques, with motivations such as accelerating change ofbasis algorithms (FGLM) or improving their complexity.We first define and characterize multidimensional linear recursive sequencesfor $0$...

  16. Probabilistic prediction of fatigue damage based on linear fracture mechanics

    Directory of Open Access Journals (Sweden)

    M. Krejsa

    2017-01-01

    Full Text Available Paper describes in detail and gives example of the probabilistic assessment of a steel structural element subject to fatigue load, particular attention being paid to cracks from the edge and those from surface. Fatigue crack damage depends on a number of stress range cycles. Three sizes are important for the characteristics of the propagation of fatigue cracks - the initial size, detectable size and acceptable size. The theoretical model of fatigue crack progression in paper is based on a linear fracture mechanics. When determining the required degree of reliability, it is possible to specify the time of the first inspection of the construction which will focus on the fatigue damage. Using a conditional probability, times for subsequent inspections can be determined. For probabilistic calculation of fatigue crack progression was used the original and new probabilistic methods - the Direct Optimized Probabilistic Calculation (“DOProC”, which is based on optimized numerical integration. The algorithm of the probabilistic calculation was applied in the FCProbCalc code (“Fatigue Crack Probabilistic Calculation”, using which is possible to carry out the probabilistic modelling of propagation of fatigue cracks in a user friendly environment very effectively.

  17. Wavelet-based LASSO in functional linear regression.

    Science.gov (United States)

    Zhao, Yihong; Ogden, R Todd; Reiss, Philip T

    2012-07-01

    In linear regression with functional predictors and scalar responses, it may be advantageous, particularly if the function is thought to contain features at many scales, to restrict the coefficient function to the span of a wavelet basis, thereby converting the problem into one of variable selection. If the coefficient function is sparsely represented in the wavelet domain, we may employ the well-known LASSO to select a relatively small number of nonzero wavelet coefficients. This is a natural approach to take but to date, the properties of such an estimator have not been studied. In this paper we describe the wavelet-based LASSO approach to regressing scalars on functions and investigate both its asymptotic convergence and its finite-sample performance through both simulation and real-data application. We compare the performance of this approach with existing methods and find that the wavelet-based LASSO performs relatively well, particularly when the true coefficient function is spiky. Source code to implement the method and data sets used in the study are provided as supplemental materials available online.

  18. Observer-based consensus in networks of discrete-time switched linear dynamics under a fixed topology

    Science.gov (United States)

    Xin, Youming; Li, Yuxia

    2016-09-01

    This paper considers the consensus problem of discrete-time switched linear multi-agent systems under a fixed communication topology. An observer-based protocol with sampled data is proposed for solving such a problem. Assume that the digraph has a directed spanning tree and that all switched subsystem of each agent are stabilisable and detectable. It is shown that the proposed protocol solves the consensus problem when the sampling period is sufficiently small and the average dwell time of the switching signal is sufficiently large. Moreover, to reduce the conservatism, a sufficient condition for consensus is obtained to design the feedback gain matrices and the observer gain matrices by linear matrix inequalities, which guarantee that consensus can be achieved when the sampling period and the average dwell time are in the general case. Finally, the effectiveness of the theoretical results is demonstrated through an example.

  19. Research on Method of Multisensor Distributed Track Fusion Based on Feedback Integration

    Institute of Scientific and Technical Information of China (English)

    YANGGuosheng; WENChenglin; TANMin

    2003-01-01

    Multisensor distributed track fusion based on feedback integration is studied in this paper. Firstly,the tracking algorithms of each sensor in local (processor)and the track fusion algorithm on the basis of global in-formation in center (processor) are given after the general structure of multisensor distributed track fusion based on feedback integration is put forward. Secondly, one step tar-get state predictions along with covariance matrixes are fed back to the interrelated sensors to form new tracking gates for the corresponding targets, and then the intersection of the new tracking gate and the original gate formed before feedback for a certain target is taken as the effective track-ing gate for the next estimation, to decrease the computing load of PDA (probability data association). In addition,target instantiation is given to the sensor that has not ob-tained the target track, while other sensors have obtained.At last, take IR and radar as an example, simulation re-searches are performed both on the original algorithm and the one presented by this paper.

  20. Neural network-based optimal adaptive output feedback control of a helicopter UAV.

    Science.gov (United States)

    Nodland, David; Zargarzadeh, Hassan; Jagannathan, Sarangapani

    2013-07-01

    Helicopter unmanned aerial vehicles (UAVs) are widely used for both military and civilian operations. Because the helicopter UAVs are underactuated nonlinear mechanical systems, high-performance controller design for them presents a challenge. This paper introduces an optimal controller design via an output feedback for trajectory tracking of a helicopter UAV, using a neural network (NN). The output-feedback control system utilizes the backstepping methodology, employing kinematic and dynamic controllers and an NN observer. The online approximator-based dynamic controller learns the infinite-horizon Hamilton-Jacobi-Bellman equation in continuous time and calculates the corresponding optimal control input by minimizing a cost function, forward-in-time, without using the value and policy iterations. Optimal tracking is accomplished by using a single NN utilized for the cost function approximation. The overall closed-loop system stability is demonstrated using Lyapunov analysis. Finally, simulation results are provided to demonstrate the effectiveness of the proposed control design for trajectory tracking.

  1. Novel UEP LT Coding Scheme with Feedback Based on Different Degree Distributions

    Directory of Open Access Journals (Sweden)

    Li Ya-Fang

    2016-01-01

    Full Text Available Traditional unequal error protection (UEP schemes have some limitations and problems, such as the poor UEP performance of high priority data and the seriously sacrifice of low priority data in decoding property. Based on the reasonable applications of different degree distributions in LT codes, this paper puts forward a novel UEP LT coding scheme with a simple feedback to compile these data packets separately. Simulation results show that the proposed scheme can effectively protect high priority data, and improve the transmission efficiency of low priority data from 2.9% to 22.3%. Furthermore, it is fairly suitable to apply this novel scheme to multicast and broadcast environments since only a simple feedback introduced.

  2. Inner structure detection by optical tomography technology based on feedback of microchip Nd:YAG lasers.

    Science.gov (United States)

    Xu, Chunxin; Zhang, Shulian; Tan, Yidong; Zhao, Shijie

    2013-05-20

    We describe a new optical tomography technology based on feedback of microchip Nd:YAG lasers. In the case of feedback light frequency-shifted, light can be magnified by a fact of 10(6) in the Nd:YAG microchip lasers, which makes it possible to realize optical tomography with a greater depth than current optical tomography. The results of the measuring and imaging of kinds of samples are presented, which demonstrate the feasibility and potential of this approach in the inner structure detection. The system has a lateral resolution of ~1 μm, a vertical resolution of 15 μm and a longitudinal scanning range of over 10mm.

  3. Feedback Scheduling of Model-based Networked Control Systems with Flexible Workload

    Institute of Scientific and Technical Information of China (English)

    Xian-Ming Tang; Jin-Shou Yu

    2008-01-01

    In this paper, a novel control structure called feedback scheduling of model-based networked control systems is proposed to cope with a flexible network load and resource constraints. The state update time is adjusted according to the real-time network congestion situation. State observer is used under the situation where the state of the controlled plant could not be acquired. The stability criterion of the proposed structure is proved with time-varying state update time. On the basis of the stability of the novel system structure, the compromise between the control performance and the network utilization is realized by using feedback scheduler.Examples are provided to show the advantage of the proposed control structure.

  4. Predictor-Based Neural Dynamic Surface Control for Uncertain Nonlinear Systems in Strict-Feedback Form.

    Science.gov (United States)

    Peng, Zhouhua; Wang, Dan; Wang, Jun

    2016-06-22

    This paper presents a predictor-based neural dynamic surface control (PNDSC) design method for a class of uncertain nonlinear systems in a strict-feedback form. In contrast to existing NDSC approaches where the tracking errors are commonly used to update neural network weights, a predictor is proposed for every subsystem, and the prediction errors are employed to update the neural adaptation laws. The proposed scheme enables smooth and fast identification of system dynamics without incurring high-frequency oscillations, which are unavoidable using classical NDSC methods. Furthermore, the result is extended to the PNDSC with observer feedback, and its robustness against measurement noise is analyzed. Numerical and experimental results are given to demonstrate the efficacy of the proposed PNDSC architecture.

  5. Evidence based practice: laboratory feedback informs forensic specimen collection in NSW.

    Science.gov (United States)

    Nittis, Maria; Stark, Margaret

    2014-07-01

    The importance of having clear, evidence-based guidelines for the taking of forensic samples from suspects detained in police custody (persons of interest) and complainants of crime is essential for forensic practitioners. The need for such guidelines was seen as desirable in New South Wales (NSW) and a working group was set up comprising scientists, practitioners and police. Feedback from the laboratory regarding the results of the specimens taken by forensic practitioners throughout the State was received and analysed. This has resulted in changes to current practice and highlighted the need for further research in this area. It has also highlighted areas that have not changed in response to evidence A quality service demands transparency, process review, relevant research and feedback in order to progress. Examiners need to obtain the results for their cases in order to reinforce the value of the service they provide as well as to monitor and, where necessary, improve their forensic collection skills.

  6. The Simulation of the Brush Stroke Based on Force Feedback Technology

    Directory of Open Access Journals (Sweden)

    Chao Guo

    2015-01-01

    Full Text Available A novel simulation method of the brush stroke is proposed by applying force feedback technology to the virtual painting process. The relationship between force and the brush deformation is analyzed, and the spring-mass model is applied to construct the brush model, which can realistically simulate the brush morphological changes according to the force exerted on it. According to the deformation of the brush model at a sampling point, the brush footprint between the brush and the paper is calculated in real time. Then, the brush stroke is obtained by superimposing brush footprints along sampling points, and the dynamic painting of the brush stroke is implemented. The proposed method has been successfully applied to the virtual painting system based on the force feedback technology. In this system, users can implement the painting in real time with a Phantom Desktop haptic device, which can effectively enhance reality to users.

  7. A feedback-based inverse heat transfer method to estimate unperturbed temperatures in wellbores

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa-Paredes, Gilberto [Area de Ingenieria en Recursos Energeticos, Universidad Autonoma Metropolitana-Iztapalapa, Apartado Postal 55-534, Mexico D.F. 09340 (Mexico); Espinosa-Martinez, Erick G. [Retorno Quebec 6, Col. Burgos de Cuernavaca 62580, Temixco, Mor. (Mexico)

    2009-01-15

    This paper presents a feedback-based strategy to solve an inverse heat transfer problem for the estimation of unperturbed formation temperatures (UFT) from measured temperatures in wellbores. The feedback function uses the error between the measured and estimated temperatures during the shut-in process. Thus, an inverse heat transfer problem was solved in this way since the UFT represents the unknown initial conditions and the measured temperatures in the wellbore represents the particular solution of the PDE'S governing the heat transfer process in the formation and in the wellbore system. The performance of the method is illustrated via numerical simulations of two wells: (a) oil well FE-1227 from the Gulf of Mexico maritime zone and (b) well CP-0512 from Cerro Prieto Mexican geothermal field. (author)

  8. High brightness laser source based on polarization coupling of two diode lasers with asymmetric feedback

    DEFF Research Database (Denmark)

    Thestrup, B.; Chi, M.; Sass, B.

    2003-01-01

    In this letter, we show that polarization coupling and asymmetric diode-laser feedback can be used to combine two diode-laser beams with low spatial coherence into a single beam with high spatial coherence. The coupled laser source is based on two similar laser systems each consisting of a 1 mumx......200 mum broad area laser diode applied with a specially designed feedback circuit. When operating at two times threshold, 50% of the freely running system output power is obtained in a single beam with an M-2 beam quality factor of 1.6+/-0.1, whereas the M-2 values of the two freely running diode...... lasers are 29+/-1 and 34+/-1, respectively. (C) 2003 American Institute of Physics....

  9. Direct and Indirect Written Corrective Feedback in the Context of Genre-based Instruction on Job Application Letter Writing

    Directory of Open Access Journals (Sweden)

    Mostafa Mirzaii

    2013-10-01

    Full Text Available Despite the fact that a considerable proportion of today’s writing programs operate according to the principles of genre-based instruction, research has not adequately dealt with the teaching of various genres (e.g., job application letters. Nor has research, to date, attempted to address the issue of written corrective feedback in conjunction with genre-based instruction. This study, therefore, aimed to investigate the impact of written corrective feedback in the context of genre-based instruction on job application letters. To this end, 120 Iranian advanced-level EFL learners at Kish Institute of Science and Technology participated in the present study. After administering the TOEFL test, 80 students scoring within ±1 SD of the mean score were randomly assigned to one of two experimental groups?namely, Direct Feedback Group or Indirect Feedback Group. Having sat a writing pretest, the participants received genre-based instruction on how to compose job application letters. Meanwhile, they were supplied with direct or indirect feedback on their writing. Following this instruction, a writing posttest was administered, the results of which showed that direct corrective feedback was more effective than indirect corrective feedback in the context of genre-based instruction on letters of job application.

  10. Modeling T cell antigen discrimination based on feedback control of digital ERK responses.

    Directory of Open Access Journals (Sweden)

    2005-11-01

    Full Text Available T-lymphocyte activation displays a remarkable combination of speed, sensitivity, and discrimination in response to peptide-major histocompatibility complex (pMHC ligand engagement of clonally distributed antigen receptors (T cell receptors or TCRs. Even a few foreign pMHCs on the surface of an antigen-presenting cell trigger effective signaling within seconds, whereas 1 x 10(5-1 x 10(6 self-pMHC ligands that may differ from the foreign stimulus by only a single amino acid fail to elicit this response. No existing model accounts for this nearly absolute distinction between closely related TCR ligands while also preserving the other canonical features of T-cell responses. Here we document the unexpected highly amplified and digital nature of extracellular signal-regulated kinase (ERK activation in T cells. Based on this observation and evidence that competing positive- and negative-feedback loops contribute to TCR ligand discrimination, we constructed a new mathematical model of proximal TCR-dependent signaling. The model made clear that competition between a digital positive feedback based on ERK activity and an analog negative feedback involving SH2 domain-containing tyrosine phosphatase (SHP-1 was critical for defining a sharp ligand-discrimination threshold while preserving a rapid and sensitive response. Several nontrivial predictions of this model, including the notion that this threshold is highly sensitive to small changes in SHP-1 expression levels during cellular differentiation, were confirmed by experiment. These results combining computation and experiment reveal that ligand discrimination by T cells is controlled by the dynamics of competing feedback loops that regulate a high-gain digital amplifier, which is itself modulated during differentiation by alterations in the intracellular concentrations of key enzymes. The organization of the signaling network that we model here may be a prototypic solution to the problem of achieving

  11. A Continuous Feedback Optimal Control based on Second-Variations for Problems with Control Constraints

    CERN Document Server

    Olympio, Joris T

    2011-01-01

    The paper describes a continuous second-variation algorithm to solve optimal control problems where the control is defined on a closed set. A second order expansion of a Lagrangian provides linear updates of the control to construct a locally feedback optimal control of the problem. Since the process involves a backward and a forward stage, which require storing trajectories, a method has been devised to accurately store continuous solutions of ordinary differential equations. Thanks to the continuous approach, the method adapts implicitly the numerical time mesh. The novel method is demonstrated on bang-bang optimal control problems, showing the suitability of the method to identify automatically optimal switching points in the control.

  12. Chaos synchronization based on a continuous chaos control method in semiconductor lasers with optical feedback.

    Science.gov (United States)

    Murakami, A; Ohtsubo, J

    2001-06-01

    Chaos synchronization using a continuous chaos control method was studied in two identical chaotic laser systems consisting of semiconductor lasers and optical feedback from an external mirror. Numerical calculations for rate equations indicate that the stability of chaos synchronization depends significantly on the external mirror position. We performed a linear stability analysis for the rate equations. Our results show that the stability of the synchronization is much influenced by the mode interaction between the relaxation oscillation frequency of the semiconductor laser and the external cavity frequency. Due to this interaction, an intensive mode competition between the two frequencies destroys the synchronization, but stable synchronization can be achieved when the mode competition is very weak.

  13. The impact of computer-based feedback on students’ written work

    Directory of Open Access Journals (Sweden)

    Khaled El Ebyary

    2010-12-01

    automatic computer-based holistic scores and computer-based feedback (CBF on written work are available and therefore have the potential to deal with this issue. Criterion is one such tool that claims to be able to provide automated feedback at word, sentence, paragraph and text level, but there is still a need for more research into the practical value of providing feedback on L2 writing. Quantitative and qualitative data about feedback practice was collected from 31 instructors and 549 Egyptian trainee EFL teachers using pre-treatment questionnaires, interviews and focus groups. 24 of the trainees then received computer-based feedback using Criterion on two drafts of essays submitted on each of 4 topics. Data recorded by the software suggested a positive effect on the quality of students’ second drafts and subsequent submissions, and post-treatment questionnaires, interviews and focus groups showed a positive effect on the students’ attitudes towards feedback.

  14. Vietnamese EFL Students' Perceptions of Noticing-Based Collaborative Feedback on Their Writing Performance

    Science.gov (United States)

    Dang, Trang Thi Doan

    2016-01-01

    It has been theoretically and empirically acknowledged that collaborative feedback is beneficial to learning achievement. However, feedback research remains relatively contentious due to learners' differing viewpoints on how feedback is best given. Although a large number of studies have explored learners' perspectives on collaborative feedback,…

  15. Audio Feedback -- Better Feedback?

    Science.gov (United States)

    Voelkel, Susanne; Mello, Luciane V.

    2014-01-01

    National Student Survey (NSS) results show that many students are dissatisfied with the amount and quality of feedback they get for their work. This study reports on two case studies in which we tried to address these issues by introducing audio feedback to one undergraduate (UG) and one postgraduate (PG) class, respectively. In case study one…

  16. Feedback linearization control of constant output power for variable pitch wind turbine%变桨距风力发电机组恒功率反馈线性化控制

    Institute of Scientific and Technical Information of China (English)

    杨俊华; 郑俭华; 杨梦丽; 吴捷

    2012-01-01

    在额定风速以上时,为保证风电机组的安全稳定运行,需要降低风力机捕获风能,使风力机的转速及功率维持在额定值,基于微分几何反馈线性化方法,提出变桨距风力发电机组恒功率控制策略.建立了风力机的仿射非线性模型,采用微分几何反馈线性化变换实现全局精确线性化;根据新的线性化模型,以风力机转速为输出反馈变量,叶片桨距角为输入控制变量,设计桨距角控制器;在风速高于额定值时调节风力机维持在额定转速,从而实现额定风速以上的恒功率控制.仿真结果表明,所提控制策略能较好地解决变桨距风力发电机组额定风速以上的恒功率控制问题,控制方法具有较好的适应性和鲁棒性.%When the wind speed exceeds the rated value, the wind power captured by the wind turbine must be reduced to guarantee the wind turbine to operate in the safe and stable status. A control scheme for limiting the power of the variable pitch wind turbine based on the differential geometry feedback linearized theory is proposed to keep the rotational speed and output power at the rated value. An affine nonlinear model of the wind turbine is developed and then globally exactly linearized by a differential geometry transformation. With the new linearized model, we design a novel pitch angle controller in which the output feedback variable is the rotational speed and the input control variable is the blade pitch angle. When the wind speed exceeds the rated value, the pitch angle controller changes the blade pitch angle to reduce the rotational speed back to the rated value for ensuring the constant output power. Simulation results show that, when the wind speed is above the rated value, the proposed control strategy effectively implements the constant output power control for the variable pitch wind turbine with fine flexibility and robustness.

  17. Linear-grating triboelectric generator based on sliding electrification.

    Science.gov (United States)

    Zhu, Guang; Chen, Jun; Liu, Ying; Bai, Peng; Zhou, Yu Sheng; Jing, Qingshen; Pan, Caofeng; Wang, Zhong Lin

    2013-05-08

    The triboelectric effect is known for many centuries and it is the cause of many charging phenomena. However, it has not been utilized for energy harvesting until very recently. (1-5) Here we developed a new principle of triboelectric generator (TEG) based on a fully contacted, sliding electrification process, which lays a fundamentally new mechanism for designing universal, high-performance TEGs to harvest diverse forms of mechanical energy in our daily life. Relative displacement between two sliding surfaces of opposite triboelectric polarities generates uncompensated surface triboelectric charges; the corresponding polarization created a voltage drop that results in a flow of induced electrons between electrodes. Grating of linear rows on the sliding surfaces enables substantial enhancements of total charges, output current, and current frequency. The TEG was demonstrated to be an efficient power source for simultaneously driving a number of small electronics. The principle established in this work can be applied to TEGs of different configurations that accommodate the needs of harvesting energy and/or sensing from diverse mechanical motions, such as contacted sliding, lateral translation, and rotation/rolling.

  18. Bearing Fault Diagnosis Based on Statistical Locally Linear Embedding

    Directory of Open Access Journals (Sweden)

    Xiang Wang

    2015-07-01

    Full Text Available Fault diagnosis is essentially a kind of pattern recognition. The measured signal samples usually distribute on nonlinear low-dimensional manifolds embedded in the high-dimensional signal space, so how to implement feature extraction, dimensionality reduction and improve recognition performance is a crucial task. In this paper a novel machinery fault diagnosis approach based on a statistical locally linear embedding (S-LLE algorithm which is an extension of LLE by exploiting the fault class label information is proposed. The fault diagnosis approach first extracts the intrinsic manifold features from the high-dimensional feature vectors which are obtained from vibration signals that feature extraction by time-domain, frequency-domain and empirical mode decomposition (EMD, and then translates the complex mode space into a salient low-dimensional feature space by the manifold learning algorithm S-LLE, which outperforms other feature reduction methods such as PCA, LDA and LLE. Finally in the feature reduction space pattern classification and fault diagnosis by classifier are carried out easily and rapidly. Rolling bearing fault signals are used to validate the proposed fault diagnosis approach. The results indicate that the proposed approach obviously improves the classification performance of fault pattern recognition and outperforms the other traditional approaches.

  19. Multivariate statistical modelling based on generalized linear models

    CERN Document Server

    Fahrmeir, Ludwig

    1994-01-01

    This book is concerned with the use of generalized linear models for univariate and multivariate regression analysis. Its emphasis is to provide a detailed introductory survey of the subject based on the analysis of real data drawn from a variety of subjects including the biological sciences, economics, and the social sciences. Where possible, technical details and proofs are deferred to an appendix in order to provide an accessible account for non-experts. Topics covered include: models for multi-categorical responses, model checking, time series and longitudinal data, random effects models, and state-space models. Throughout, the authors have taken great pains to discuss the underlying theoretical ideas in ways that relate well to the data at hand. As a result, numerous researchers whose work relies on the use of these models will find this an invaluable account to have on their desks. "The basic aim of the authors is to bring together and review a large part of recent advances in statistical modelling of m...

  20. Stochastic thermodynamics based on incomplete information: generalized Jarzynski equality with measurement errors with or without feedback

    Science.gov (United States)

    Wächtler, Christopher W.; Strasberg, Philipp; Brandes, Tobias

    2016-11-01

    In the derivation of fluctuation relations, and in stochastic thermodynamics in general, it is tacitly assumed that we can measure the system perfectly, i.e., without measurement errors. We here demonstrate for a driven system immersed in a single heat bath, for which the classic Jarzynski equality =1 holds, how to relax this assumption. Based on a general measurement model akin to Bayesian inference we derive a general expression for the fluctuation relation of the measured work and we study the case of an overdamped Brownian particle and of a two-level system in particular. We then generalize our results further and incorporate feedback in our description. We show and argue that, if measurement errors are fully taken into account by the agent who controls and observes the system, the standard Jarzynski-Sagawa-Ueda relation should be formulated differently. We again explicitly demonstrate this for an overdamped Brownian particle and a two-level system where the fluctuation relation of the measured work differs significantly from the efficacy parameter introduced by Sagawa and Ueda. Instead, the generalized fluctuation relation under feedback control, =1, holds only for a superobserver having perfect access to both the system and detector degrees of freedom, independently of whether or not the detector yields a noisy measurement record and whether or not we perform feedback.