Download or read book Model based Feedback Control of Cavity Resonance written by Clarence W. Rowley and published by . This book was released on 2006 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents results of experiments and numerical simulations studying closed-loop feedback control of oscillations in the compressible flow past a rectangular cavity. When weapons bays are exposed to high flow speeds, extremely large pressure fluctuations result, and are often large enough to cause structural damage to the aircraft and internal stores. The goal of this work is to design an implement a model-based feedback controller to suppress oscillations in the flow past a cavity over a range of operating conditions, using much less power than open-loop techniques; and to understand the physics well enough to allow the techniques to be reliably transferred to full-scale aircraft. Several specific advances have been made in this work, relevant for cavity flow control as well as for other closed-loop flow control applications. Theoretical models are presented for temporally developing shear layers and cavity oscillations at the flow conditions used in both simulations and experiments. These models can be used to construct dynamic observers, which reconstruct the full flow information from a limited number of sensors, and significantly outperform static estimators such as Linear Stochastic Estimation (LSE).
Download or read book Active Flow Control written by Rudibert King and published by Springer Science & Business Media. This book was released on 2007-08-29 with total page 441 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains contributions presented at the Active Flow Control 2006 conference, held September 2006, at the Technische Universität Berlin, Germany. It contains a well balanced combination of theoretical and experimental state-of-the-art results of Active Flow Control. Coverage combines new developments in actuator technology, sensing, robust and optimal open- and closed-loop control and model reduction for control.
Download or read book Model based Feedback Control of Subsonic Cavity Flows Control Design written by Xin Yuan and published by . This book was released on 2006 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In this dissertation, we present and discuss development, implementation, and experimental results of reduced-order model based feedback control of subsonic cavity flows. Model based feedback control of subsonic flows have been studied and implemented by the flow control group at the Collaborative Center of Control Science (CCCS) at the Ohio State University (OSU). The team, composed of researchers from the departments of Electrical Engineering and Mechanical Engineering at the Ohio State, the Air Force Research Laboratory, and NASA Glenn Research Center, possesses synergistic capabilities in all of the required multidisciplinary areas of experimental data acquisition, computational flow simulation, low dimensional modeling, controller design, and experimental validation. The goal of the CCCS effort is to develop tools and methodologies for the use of closed-loop aerodynamic flow control to manipulate the flow over maneuvering air vehicles. The problem chosen for the initial study by the CCCS flow team is control of the resonant noise generated by subsonic flow past an open cavity. This phenomenon is characterized by a strong coupling between the flow dynamics and the flow-induced acoustic field that can lead to self-sustained resonance. Two approaches towards model development have been studied in this dissertation. One aims at representing the physical properties of the system by dynamical models in transfer function forms, referred to as the physics-based linear model in this dissertation. The other approach we have followed is based on proper orthogonal decomposition (POD) and Galerkin projection methods involving the flow governing equations, which is referred to as the nonlinear model or Galerkin model in the dissertation. Each model mentioned above can be further divided into two types: model derived from numerical simulation data and model derived from real time experimental data. Different types of feedback controllers have been designed for corresponding flow models. Closed-loop system performance has been evaluated by both numerical simulation and experimental implementation as well. These results confirm that model based feedback control represents a promising approach to flow control even in its current infancy state.
Download or read book 2015 ICU International Congress on Ultrasonics Abstract Book Metz France Declercq N F editor 2015 written by Nico F. Declercq and published by Nico F. Declercq. This book was released on 2015-05-11 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: The compilation of this book has been made possible with the help of Didier Cassereau, Bertrand Dubus and John Fritsch with support from the Scientific and Technical Committee of 2015 ICU.
Download or read book Active Control Of Aircraft Cabin Noise written by Ignazio Dimino and published by World Scientific. This book was released on 2015-07-13 with total page 303 pages. Available in PDF, EPUB and Kindle. Book excerpt: 'The text is well written and supported by clear and useful illustrations. This would be a useful textbook for postgraduate or advanced undergraduate studies and would also make a good introductory text for engineers moving into the field. The literature survey and bibliography provide a useful starting point for further study.'The Aeronautical JournalActive Control of Aircraft Cabin Noise provides a bridge to fill the gap between robust control theory and practical applications of active noise control systems in aircraft cabin. Both the possibilities and limitations of structural solutions to enhance aircraft cabin comfort by reducing interior noise are discussed supported by a wide range of topics in engineering, from finite element modeling to multichannel adaptive feed-forward control, usually dealt separately in the literature. In addition, experimental noise attenuation results with passengers' subjective perceptions predicting the effects of cabin noise on comfort assessments is examined. Theoretical and experimental research is detailed enough to capture the interest of the non-expert in engineering who wishes to have an overview of some of the active noise control applications in aircraft. This book may be used as an advanced textbook by graduate and undergraduate students in aeronautical engineering, and would be an authoritative resource book for research into the subject.
Download or read book Feedback Control of Oscillations in Combustion and Cavity Flows written by Simon J. Illingworth and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis considers the control of combustion oscillations, motivated by the susceptibility of lean premixed combustion to such oscillations, and the long and expensive development and commissioning times that this is giving rise to. The controller used is both closed-loop, employing an actuator to modify some system parameter in response to a measured signal, and adaptive, meaning that it is able to maintain control over a wide range of operating conditions. The controller is applied to combustion systems with annular geometries, where instabilities can occur both longitudinally and azimuthally, and which require multiple sensors and multiple actuators for control. One of the requirements of Lyapunov-based adaptive control which is particularly troublesome for combustion systems is then addressed: that the sign of the high-frequency gain of the open-loop system is known. We address it by using an adaptive controller which employs a Nussbaum gain, and successfully apply it experimentally to combustion oscillations in a Rijke tube. Another type of fluid-acoustic resonance is then considered: the compressible flow past a shallow cavity. We start by finding a linear model of the cavity flow's dynamics, or its `transfer function', which we identify from direct numerical simulations. We compare this measured transfer function to that given by a conceptual model which is based on the Rossiter mechanism, and which models each component of the flow physics separately. We then look at using closed-loop control to eliminate these cavity oscillations. We start by designing a robust $\mathcal{H}-2$ controller based on a balanced reduced order model of the system, the model being provided by the Eigensystem Realization Algorithm (ERA). The robust controller provides closed-loop stability over a much wider Mach number range than seen in previous studies. Finally, we look at the suitability of the adaptive controller, earlier developed for combustion oscillations, for the cavity. Based on some general properties of the cavity flow, and by using collocated control, the oscillations are eliminated at all Mach numbers tested in the range $0.4 \le M \le 0.8$.
Download or read book Model Free Stabilization by Extremum Seeking written by Alexander Scheinker and published by Springer. This book was released on 2016-12-23 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: With this brief, the authors present algorithms for model-free stabilization of unstable dynamic systems. An extremum-seeking algorithm assigns the role of a cost function to the dynamic system’s control Lyapunov function (clf) aiming at its minimization. The minimization of the clf drives the clf to zero and achieves asymptotic stabilization. This approach does not rely on, or require knowledge of, the system model. Instead, it employs periodic perturbation signals, along with the clf. The same effect is achieved as by using clf-based feedback laws that profit from modeling knowledge, but in a time-average sense. Rather than use integrals of the systems vector field, we employ Lie-bracket-based (i.e., derivative-based) averaging. The brief contains numerous examples and applications, including examples with unknown control directions and experiments with charged particle accelerators. It is intended for theoretical control engineers and mathematicians, and practitioners working in various industrial areas and in robotics.
Download or read book AIAA Journal written by American Institute of Aeronautics and Astronautics and published by . This book was released on 2008 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Investigation of Flow induced Cavity Resonance written by Paul Zoccola (Jr., J.) and published by . This book was released on 2000 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Low Level Radio Frequency Systems written by Stefan Simrock and published by Springer Nature. This book was released on 2022-03-02 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book begins with an overview of the RF control concepts and strategies. It then introduces RF system models for optimizing the system parameters to satisfy beam requirements and for controller design. In addition to systematically discussing the RF field control algorithms, it presents typical architecture and algorithms for RF signal detection and actuation. Further, the book addresses the analysis of the noise and nonlinearity in LLRF systems to provide a better understanding of the performance of the RF control system and to specify the performance requirements for different parts of the RF system. Today, accelerators require increased RF stability and more complex operation scenarios, such as providing beam for different beam lines with various parameters, and as a result LLRF systems are becoming more critical and complex. This means that LLRF system developers need have extensive knowledge of the entire accelerator complex and a wide range of other areas, including RF and digital signal processing, noise analysis, accelerator physics and systems engineering. Providing a comprehensive introduction to the basic theories, algorithms and technologies, this book enables LLRF system developers to systematically gain the knowledge required to specify, design and implement LLRF systems and integrate them with beam acceleration. It is intended for graduate students, professional engineers and researchers in accelerator physics.
Download or read book NASA Technical Paper written by and published by . This book was released on 1990 with total page 748 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 05 5258 05 5393 written by and published by . This book was released on 2005 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Extremum Seeking Control System for Control of RF Cavity Resonators written by Zahra Shahriari and published by . This book was released on 2016 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: RF cavity resonators are one of the key structures in particle accelerators. They provide accelerating field for a beam of charged particles passing through them. An RF source transmits required power for acceleration to cavity through waveguides. Due to impedance mismatch, some amount of available power generated by the RF source reflects back from the cavity. To save power and provide the maximum accelerating field, it is desirable to minimize this reflected power by equalizing the frequencies of the cavity and source. A mechanical tuner mounted on top of the cavity moves a tuner plate in or out of the cavity, thereby changing cavity's resonance frequency. In this thesis, first a mathematical dynamic model of the cavity in terms of its transient and steady state signals is provided. Then based on the dynamic model, an extremum seeking (ES) algorithm is developed to automatically reach the minimum value of the reflected power and maintain this condition by keeping the resonance frequency of the cavity equal to the source frequency. The ES algorithm is derived through a Lyapunov-based analysis and uses only reflected power as feedback signal. A gradient estimation is performed to determine the direction of movement. The proposed ES controller is further compared with classical perturbation-based ES methods. Simulation and experimental results are presented to evaluate stability and the response behavior of the algorithms in reaching the minimum condition. While both algorithms successfully minimize reflected power in finite time, the results obtained from the Lyapunov-based algorithm are faster and smoother. However, if the cavity is not perfectly coupled and the minimum reflected power is greater than zero, the performance of the proposed controller degrades due to appearance of steady state oscillation. This problem can be solved by adding an initialization phase to the controller, to track the minimum value of reflected power and update the control law with the new value of the minimum.
Download or read book 03 3565 03 3612 written by and published by . This book was released on 2003 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Collected Papers of Carl Wieman written by C. E. Wieman and published by World Scientific. This book was released on 2008 with total page 827 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carl Wieman''s contributions have had a major impact on defining the field of atomic physics as it exists today. His ground-breaking research has included precision laser spectroscopy; using lasers and atoms to provide important table-top tests of theories of elementary particle physics; the development of techniques to cool and trap atoms using laser light, particularly in inventing much simpler, less expensive ways to do this; the understanding of how atoms interact with one another and light at ultracold temperatures; and the creation of the first BoseOCoEinstein condensation in a dilute gas, and the study of the properties of this condensate. In recent years, he has also turned his attention to physics education and new methods and research in that area. This indispensable volume presents his collected papers, with annotations from the author, tracing his fascinating research path and providing valuable insight about the significance of the works. Sample Chapter(s). Introduction (197 KB). Contents: Precision Measurement and Parity Nonconservation; Laser Cooling and Trapping; BoseOCoEinstein Condensation; Science Education; Development of Research Technology. Readership: Graduates, postgraduates and researchers in atomic physics, laser physics and general physics."
Download or read book Energy Research Abstracts written by and published by . This book was released on 1993 with total page 922 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Papers from the 16th North American Conference on Molecular Beam Epitaxy written by North American Conference on Molecular Beam Epitaxy (16, 1997, Ann Arbor, Mich.) and published by . This book was released on 1998 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
