Commissioning and Initial Performance of the LHC Beam-Based Feedback Systems
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
Design of the ILC Prototype FONT4 Digital Intra-Train Beam-Based Feedback System
We present the design of the FONT4 digital intra-train beam position feedback system prototype and preliminary results of initial beam tests at the Accelerator Test Facility (ATF) at KEK. The feedback system incorporates a fast analogue beam position monitor (BPM) front-end signal processor, a digital feedback board, and a kicker driver amplifier. The short bunchtrain, comprising 3 electron bunches separated by c. 150ns, in the ATF extraction line was used to test components of the prototype feedback system
A state variable approach to the BESSY II local beam-position-feedback system
Gilpatrick, J.D.; Khan, S.; Kraemer, D. [BESSY II, Berlin (Germany)
1996-11-01
At the BESSY II facility, stability of the electron beam position and angle near insertion devices (IDs) is of utmost importance. Disturbances due to ground motion could result in unwanted broad-bandwidth beam-jitter which decreases the electron (and resultant photon) beam`s effective brightness. Therefore, feedback techniques must be used. Operating over a frequency range of < 1- to > 100-Hz, a local feedback system will correct these beam-trajectory errors using the four bumps around IDs. This paper reviews how the state-variable feedback approach can be applied to real-time correction of these beam position and angle errors. A frequency-domain solution showing beam jitter reduction is presented. Finally, this paper reports results of a beam-feedback test at BESSY I.
The problem of transverse emittance blow-up from beam injection errors in synchrotrons with nonlinear feedback systems is considered. The relative emittance growth is calculated for linear and nonlinear feedback transfer functions. Effects of an increase of the damping decrement of the beam coherent oscillations and of a decrease of the coherent transverse amplitude spread of different bunches in case of the damper with positive cubic term in the feedback transfer function are discussed
A state variable approach to the BESSY II local beam-position-feedback system
At the BESSY II facility, stability of the electron beam position and angle near insertion devices (IDs) is of utmost importance. Disturbances due to ground motion could result in unwanted broad-bandwidth beam-jitter which decreases the electron (and resultant photon) beam's effective brightness. Therefore, feedback techniques must be used. Operating over a frequency range of 100-Hz, a local feedback system will correct these beam-trajectory errors using the four bumps around IDs. This paper reviews how the state-variable feedback approach can be applied to real-time correction of these beam position and angle errors. A frequency-domain solution showing beam jitter reduction is presented. Finally, this paper reports results of a beam-feedback test at BESSY I
A super collider transverse feedback system designed to suppress injection errors, emittance growth due to external noises, and beam instabilities is considered. It is supposed that the feedback system should consist of two circuits: an injection damper operating just after injection and a super damper. To damp the emittance growth, the superdamper has to operate with the ultimate decrement close to the revolution frequency. The physics of such a feedback system and its main limitations are discussed. 9 refs.; 21 figs.; 1 tab
Development of photon beam position feedback system based on two PBPMs at HLS
In this paper, in order to stabilize the position and angle of the light source point, a new photon beam position feedback system based on the Photon Beam Position Monitors was developed on Hefei Light Source, and used to correct the position drift and angle variation of the light source at the same time. On introducing the feedback principle, the transfer function matrix is calibrated, indicating that the new system is workable and effective. (authors)
Tests of the FONT3 Linear Collider Intra-Train Beam Feedback System at the ATF
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
An automatic beam steering system for the NSLS X-17T beam line using closed orbit feedback
Initial observations of motion of the undulator radiation in the NSLS X-17T beam line clearly indicated that the beam had to be stabilized in both directions to be usable for the planned soft X-ray imaging experiments. The low frequency spectra of beam motion contained peaks in the range from dc to 60 Hz and at higher frequencies. A beam steering system employing closed orbit feedback has been designed and installed to stabilize the beam in both planes. In each plane of motion, beam position is measured with a beam position detector and a correction signal is fed back to a local four magnet orbit bump to dynamically control the angle of the radiation at the source. This paper describes the design and performance of the beam steering system
Feedback control and beam diagnostic algorithms for a multiprocessor DSP system
The multibunch longitudinal feedback system developed for use by PEP-II, ALS, and DAΦNE uses a parallel array of digital signal processors (DSPs) to calculate the feedback signals from measurements of beam motion. The system is designed with general-purpose programmable elements which allow many feedback operating modes as well as system diagnostics, calibrations, and accelerator measurements. The overall signal processing architecture of the system is illustrated. The real-time DSP algorithms and off-line postprocessing tools are presented. The problems in managing 320k samples of data collected in one beam transient measurement are discussed and our solutions are presented. Example software structures are presented showing the beam feedback process, techniques for modal analysis of beam motion (used to quantify growth and damping rates of instabilities), and diagnostic functions (such as timing adjustment of beam pick-up and kicker components). These operating techniques are illustrated with example results obtained from the system installed at the Advanced Light Source at LBL. copyright 1997 American Institute of Physics
Development of a beam position detector for an orbit feedback system in SuperKEKB
SuperKEKB, which is under construction at KEK, is an electron-positron collider aiming at 40 times larger luminosity of KEKB. Since a vertical design beam size at a collision point is as small as 50 nm in SuperKEKB, an orbit feedback system is essential for maintaining stable collision. A fast beam position detector is being developed for the orbit feedback system. Tentative target performance is a signal to noise ratio of 120dB at the input power of -3dBm and a signal bandwidth of 1 kHz. The detector consists of an analogue part to convert 509 MHz-beam-signal to 17 MHz-IF-signal and a digital part which has a ADC, two CIC decimation filters and a FIR filter. The paper describes results of laboratory measurement obtained so far and items to be improved for a final version. (author)
Feedback system for suppression of the beam self-bunching in the U-70 accelerators
Slow removal of proton beams from the U-70 proton synchrotron is complicated by the beam self-bunching effect, circulating on the magnetic field plateau. The effect is caused by the particles interaction with the operating 40-type oscillations of the disconnected HF-resonators, The system for suppression of this instability through the feedback channel (F C) by the beam, closed through one of the HF-resonators is proposed. Th principles of building the system are discussed and choice of its working parameters is explained. The results of the circuit-engineering modeling of the F C electrical scheme are presented. The proposed system is a version for technical solution of the problem on the beam self-bunching, considered within the frames of the program on the U-70 accelerator modernization
Performance of the FONT3 Fast Analogue Intra-Train Beam-Based Feedback System at ATF
We report results of beam tests of the FONT3 intra-train position feedback system prototype at the Accelerator Test Facility (ATF) at KEK. The feedback system incorporates a novel beam position monitor (BPM) processor with 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 feedback system. The achieved latency of 23ns provides a demonstration of intra-train feedback on very short timescales relevant even for the CLIC Linear Collider design
Sayed, Mostafa M.
2014-11-01
Spectrum sharing systems have been introduced to alleviate the problem of spectrum scarcity by allowing an unlicensed secondary user (SU) to share the spectrum with a licensed primary user (PU) under acceptable interference levels to the primary receiver (PU-Rx). In this paper, we consider a secondary link composed of a secondary transmitter (SU-Tx) equipped with multiple antennas and a single-antenna secondary receiver (SU-Rx). The secondary link is allowed to share the spectrum with a primary network composed of multiple PUs communicating over distinct frequency spectra with a primary base station. We develop a transmission scheme where the SU-Tx initially broadcasts a set of random beams over all the available primary spectra for which the PU-Rx sends back the index of the spectrum with the minimum interference level, as well as information that describes the interference value, for each beam. Based on the feedback information on the PU-Rx, the SU-Tx adapts the transmitted beams and then resends the new beams over the best primary spectrum for each beam to the SU-Rx. The SU-Rx selects the beam that maximizes the received signal-to-interference-plus-noise ratio (SINR) to be used in transmission over the next frame. We consider three cases for the level of feedback information describing the interference level. In the first case, the interference level is described by both its magnitude and phase; in the second case, only the magnitude is considered; and in the third case, we focus on a q-bit description of its magnitude. In the latter case, we propose a technique to find the optimal quantizer thresholds in a mean-square-error sense. We also develop a statistical analysis for the SINR statistics and the capacity and bit error rate of the secondary link and present numerical results that study the impact of the different system parameters.
The intensity feedback system at Heidelberg Ion-Beam Therapy Centre
Schoemers, Christian, E-mail: christian.schoemers@med.uni-heidelberg.de; Feldmeier, Eike; Naumann, Jakob; Panse, Ralf; Peters, Andreas; Haberer, Thomas
2015-09-21
At Heidelberg Ion-Beam Therapy Centre (HIT), more than 2500 tumour patients have been treated with charged particle beams since 2009 using the raster scanning method. The tumour is irradiated slice-by-slice, each slice corresponding to a different beam energy. For the particle dose of each raster point the pre-irradiation by more distal slices has to be considered. This leads to highly inhomogeneous dose distributions within one iso-energy slice. The particles are extracted from the synchrotron via transverse RF knock-out. A pure feed forward control cannot take into account fluence inhomogeneities or deal with intensity fluctuations. So far, fluctuations have been counteracted by a reduced scanning velocity. We now added a feedback loop to the extraction system. The dose monitoring ionisation chambers in front of the patient have been coupled to the extraction device in the synchrotron. Characterization and implementation of the intensity feedback system into the HIT facility is described here. By its implementation the treatment time has been reduced by 10% in average.
Christian, G B; Bett, D R; Blaskovic Kraljevic, N; Burrows, P N; Davis, M R; Gerbershagen, A; Perry, C; Constance, B; Resta-Lopez, J
2012-01-01
A prototype Interaction Point beam-based feedback system for future electron-positron colliders, such as the International Linear Collider, has been designed and tested on the extraction line of the KEK Accelerator Test Facility (ATF). The FONT5 intra-train feedback system aims to stabilize the beam orbit by correcting both the position and angle jitter in the vertical plane on bunch-tobunch time scales, providing micron-level stability 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 kickerdrive amplifiers. The latest results from beam tests at ATF2 will be presented, including the system latency and correction performance.
Roth, Andre
2012-12-15
At the Electron Stretcher Facility ELSA an upgrade of the internal beam current up to 200 mA would be desirable in order to increase the intensity of the extracted electron beam for the future experimental hadron physics program. However, such an upgrade is mainly limited by the excitation of coherent beam instabilities in the stretcher ring. As active counteraction, broadband bunch-by-bunch feedback-systems for the longitudinal, as well as for both transverse planes were installed. After detection of the motion of each of the 27 4 stored bunches via beam position monitors, the systems determine independent correction signals for each bunch using digital signal processors. The amplified correction signals are applied to the beam by means of broadband longitudinal and transverse kicker structures. The detailed setup, the commissioning procedure and measurement results of the damping performance of the systems are presented. In addition, the operation of the longitudinal system during the fast energy ramp of 4 GeV/s from 1.2 GeV to 3.2 GeV is investigated.
Lonza, M
2014-01-01
Coupled-bunch instabilities excited by the interaction of the particle beam with its surroundings can seriously limit the performance of circular particle accelerators. These instabilities can be cured by the use of active feedback systems based on sensors capable of detecting the unwanted beam motion and actuators that apply the feedback correction to the beam. Advances in electronic technology now allow the implementation of feedback loops using programmable digital systems. Besides important advantages in terms of flexibility and reproducibility, digital systems open the way to the use of novel diagnostic tools and additional features. We first introduce coupled-bunch instabilities, analysing the equation of motion of charged particles and the different modes of oscillation of a multi-bunch beam, showing how they can be observed and measured. Different types of feedback systems will then be presented as examples of real implementations that belong to the history of multi-bunch feedback systems. The main co...
Linearizing Intra-Train Beam-Beam Deflection Feedback
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
Beam position monitoring and feedback steering system at the photon factory
A version of the beam steering servo system was used to vertically position and stabilize the synchrotron radiation beam at the Photon Factory. System components included a photon beam position monitor located 12 m from the bend magnet source point, a servo controller containing frequency compensation and gain circuits, and a 3-magnet orbital bump steering system. Two types of position monitor, one an ion chamber and the other on in-vacuum device, were used in the system. Vertical beam position noise spectra obtained from these monitors showed predominant peaks occurring at 14.5 Hz, 50 Hz, and at several other frequencies in the 1 to 100 Hz range. The closed-loop system was able to reduce low frequency positional offsets (< 0.1 Hz) by a factor of 1000, and the 14.5 Hz oscillation by a factor of 6
Feedback Systems for Linear Colliders
Hendrickson, L.; Grossberg, P.; Himel, T.; Minty, M.; Phinney, N.; Raimondi, P.; Raubenheimer, T.; Shoaee, H.; Tenenbaum, P.
2001-01-01
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...
LHC beam stability and feedback control
Steinhagen, Ralph
2007-07-20
This report presents the stability and the control of the Large Hadron Collider's (LHC) two beam orbits and their particle momenta using beam-based feedback systems. The aim of this report is to contribute to a safe and reliable LHC commissioning and machine operation. The first part of the analysis gives an estimate of the expected sources of orbit and energy perturbations that can be grouped into environmental sources, machine-inherent sources and machine element failures: the slowest perturbation due to ground motion, tides, temperature fluctuations of the tunnel and other environmental influences are described in this report by a propagation model that is both qualitatively and quantitatively supported by geophone and beam motion measurements at LEP and other CERN accelerators. The second part of this analysis deals with the control of the two LHC beams' orbit and energy through automated feedback systems. Based on the reading of the more than 1056 beam position monitors (BPMs) that are distributed over the machine, a central global feedback controller calculates new deflection strengths for the more than 1060 orbit corrector magnets (CODs) that are suitable to correct the orbit and momentum around their references. this report provides an analysis of the BPMs and CODs involved in the orbit and energy feedback. The BPMs are based on a wide-band time normaliser circuit that converts the transverse beam position reading of each individual particle bunch into two laser pulses that are separated by a time delay and transmitted through optical fibres to an acquisition card that converts the delay signals into a digital position. A simple error model has been tested and compared to the measurement accuracy of LHC type BPMs, obtained through beam-based measurements in the SPS. The average beam position is controlled through 1060 superconducting and individually powered corrector dipole magnets. The proposed correction in 'time-domain' consists of a
LHC beam stability and feedback control
This report presents the stability and the control of the Large Hadron Collider's (LHC) two beam orbits and their particle momenta using beam-based feedback systems. The aim of this report is to contribute to a safe and reliable LHC commissioning and machine operation. The first part of the analysis gives an estimate of the expected sources of orbit and energy perturbations that can be grouped into environmental sources, machine-inherent sources and machine element failures: the slowest perturbation due to ground motion, tides, temperature fluctuations of the tunnel and other environmental influences are described in this report by a propagation model that is both qualitatively and quantitatively supported by geophone and beam motion measurements at LEP and other CERN accelerators. The second part of this analysis deals with the control of the two LHC beams' orbit and energy through automated feedback systems. Based on the reading of the more than 1056 beam position monitors (BPMs) that are distributed over the machine, a central global feedback controller calculates new deflection strengths for the more than 1060 orbit corrector magnets (CODs) that are suitable to correct the orbit and momentum around their references. this report provides an analysis of the BPMs and CODs involved in the orbit and energy feedback. The BPMs are based on a wide-band time normaliser circuit that converts the transverse beam position reading of each individual particle bunch into two laser pulses that are separated by a time delay and transmitted through optical fibres to an acquisition card that converts the delay signals into a digital position. A simple error model has been tested and compared to the measurement accuracy of LHC type BPMs, obtained through beam-based measurements in the SPS. The average beam position is controlled through 1060 superconducting and individually powered corrector dipole magnets. The proposed correction in 'time-domain' consists of a proportional
A unified approach to global and local beam position feedback
The Advanced Photon Source (APS) will implement both global and local beam position feedback systems to stabilize the particle and X-ray beams for the storage ring. The global feedback system uses 40 BPMs and 40 correctors per plane. Singular value decomposition (SVD) of the response matrix is used for closed orbit correction. The local feedback system uses two X-ray BPMS, two rf BPMS, and the four-magnet local bump to control the angle and displacement of the X-ray beam from a bending magnet or an insertion device. Both the global and local feedback systems are based on digital signal processing (DSP) running at 4-kHz sampling rate with a proportional, integral, and derivative (PID) control algorithm. In this paper, we will discuss resolution of the conflict among multiple local feedback systems due to local bump closure error and decoupling of the global and local feedback systems to maximize correction efficiency. In this scheme, the global feedback system absorbs the local bump closure error and the local feedback systems compensate for the effect of global feedback on the local beamlines. The required data sharing between the global and local feedback systems is done through the fiber-optically networked reflective memory
In future B-factories, many bunches will be circulated in their rings, and thus making the bunch spacing to become very short compared with that of the present collider machines. The impedance of the rings may cause many coupled bunch beam oscillations. One possibility to damp these multi-bunch oscillations is to install an active oscillation feedback damper system. This paper discusses the transverse feedback system. (author)
Research on feedback system of synchrotron accelerator
It is a very complex problem to use feedback control system in synchrotron accelerator. Some scientists design feedback control system to make high energy beam stable in synchrotron accelerator, but it is very rare to see theoretically analysis feedback system in synchrotron accelerator by using new concept of control model. One new feedback control model is a fresh idea to discuss the feedback system more deeply. A topic about feedback control system discussed here will be useful for synchrotron accelerator design and operation. It is an good idea for some scientists and technician to continue study. (authors)
Fast Feedback System for CEBAF
M.P. Chowdhary; G.A. Krafft; H. Shoaee; W.A. Watson III
1995-10-01
A fast feedback system based on concepts of modern control theory has been implemented in the CEBAF Control System to stabilize various machine parameters. The continuous wave operation of CEBAF requires that parameters such as beam energy and position are stabilized against fast fluctuations. The beam energy must be stabilized against fast gradient and phase fluctuations in the RF accelerating system. This fast feedback system currently operates at 60 Hz rate and is integrated with EPICS. The mathematical model of the system for various feedback loops is expressed in state space formalism. The design of control law and simulation of closed-loop system response is performed using MatlabTM and SimulinkTM. This paper describes the process of designing control algorithms, implementation of the fast feedback system and operational experience with this system at CEBAF. The performance of this feedback system, while operating at much higher rates with high closed loop gain, can be enhanced by continually performing on-line identification of the system from the input and output data. System identification is the process of developing or improving an analytically derived mathematical representation of a physical system using experimental data. The current status of this feature is presented.
Social Security Administration — The Policy Feedback System (PFS) is a web application developed by the Office of Disability Policy Management Information (ODPMI) team that gathers empirical data...
Longitudinal feedback system for PEP
Allen, M.A.; Cornacchia, M.; Millich, A.
1979-02-01
Whether the wide bandwidth longitudinal feedback system described in this paper is made to act on the individual modes in frequency domain or on the individual bunches in time domain, it represents a clean and efficient way of damping the longitudinal oscillations without influencing other beam parameters such as bunch shape or synchrotron frequency distribution. The frequency domain feedback presents the advantage of providing information on which modes are unstable and on their risetimes, which may be helpful in locating dangerous resonators in the ring.
RHIC 10 Hz global orbit feedback system
Michnoff, R.; Arnold, L.; Carboni, L.; Cerniglia, P; Curcio, A.; DeSanto, L.; Folz, C.; Ho, C.; Hoff, L.; Hulsart, R.; Karl, R.; Luo, Y.; Liu, C.; MacKay, W.; Mahler, G.; Meng, W.; Mernick, K.; Minty, M.; Montag, C.; Olsen, R.; Piacentino, J.; Popken, P.; Przybylinski, R.; Ptitsyn, V.; Ritter, J.; Schoenfeld, R.; Thieberger, P.; Tuozzolo, J.; Weston, A.; White, J.; Ziminski, P.; Zimmerman, P.
2011-03-28
Vibrations of the cryogenic triplet magnets at the Relativistic Heavy Ion Collider (RHIC) are suspected to be causing the horizontal beam perturbations observed at frequencies around 10 Hz. Several solutions to counteract the effect have been considered in the past, including a local beam feedback system at each of the two experimental areas, reinforcing the magnet base support assembly, and a mechanical servo feedback system. However, the local feedback system was insufficient because perturbation amplitudes outside the experimental areas were still problematic, and the mechanical solutions are very expensive. A global 10 Hz orbit feedback system consisting of 36 beam position monitors (BPMs) and 12 small dedicated dipole corrector magnets in each of the two 3.8 km circumference counter-rotating rings has been developed and commissioned in February 2011. A description of the system architecture and results with beam will be discussed.
Beam spill structure feedback test in HIRFL-CSR
HIRFL-CSR is the post-acceleration system of the Heavy Ion Research Facility in Lanzhou and is composed of a double cooling storage ring and a radioactive beam line. The slow extraction beam from HIRFL-CSR is used in nuclear physics experiments and heavy ion therapy. 50 Hz ripple and harmonics are observed in beam spill. To improve the spill structure, the first set of control system consisting of fast Q-magnet and feedback device based FPGA is developed and installed in 2010. Spill structure feedback testing has also started. It is shown that the feedback structure has improved the spill structure, the 50 Hz ripple and its harmonics have been reduced
Lapin, V V; Yaichkov, V A; Zyatkov, O V
2004-01-01
This paper presents the results of the first stage modification of the servo-spill feedback system for the slow resonant beam extraction from the IHEP 70 GeV proton synchrotron. The system has a time delay caused by resonance evolution. In the past the time delay was estimated equal from 1ms to 1.8ms, and the maximum open loop frequency cut-off was considered equal to a few tens Hz. The servo-spill feedback system was being used with the open loop frequency cut-off no more than 20Hz for many years. The qualitative analysis of the beam motion on the phase plot, the modeling of the system on the base of the Hamilton's equations numerical solution and the analysis of the experimental frequency responses indicated that the time delay value is noticeably less than former estimations. The first stage modification of the servo-spill feedback system has increased the open loop frequency cut-off at the beginning of extraction process up to approximately 300 Hz. The suppression coefficients of the beam intensity ripple...
Generalized fast feedback system in the SLC
A generalized fast feedback system has been developed to stabilize beams at various locations in the SLC. The system is designed to perform measurements and change actuator settings to control beam states such as position, angle and energy on a pulse to pulse basis. The software design is based on the state space formalism of digital control theory. The system is database-driven, facilitating the addition of new loops without requiring additional software. A communications system, KISNet, provides fast communications links between microprocessors for feedback loops which involve multiple micros. Feedback loops have been installed in seventeen locations throughout the SLC and have proven to be invaluable in stabilizing the machine
Optimal centralized and decentralized velocity feedback control on a beam
This paper considers the optimization of a velocity feedback controller with a collocated force actuator, to minimize the kinetic energy of a simply supported beam. If the beam is excited at a single location, the optimum feedback gain varies with the position of the control system. It is shown that this variation depends partly on the location of the control force relative to the exciting force. If a distributed excitation is assumed, that is random in both time and space, a unique optimum value of the feedback gain can be found for a given control location. The effect of the control location on performance and the optimal feedback gain can then be examined and is found to be limited provided the control locations are not close to the ends of the beam. The optimization can also be performed for a multichannel velocity feedback system. Both a centralized and a decentralized controller are considered. It is shown that the difference in performance between a centralized and a decentralized controller is small, unless the control locations are closely spaced. In this case the centralized controller effectively feeds back a moment proportional to angular velocity as well as a force proportional to a velocity. It is also shown that the optimal feedback gain can be approximated on the basis of a limited model and that similar results can be achieved
Feedback control of quantum system
DONG Dao-yi; CHEN Zong-hai; ZHANG Chen-bin; CHEN Chun-lin
2006-01-01
Feedback is a significant strategy for the control of quantum system.Information acquisition is the greatest difficulty in quantum feedback applications.After discussing several basic methods for information acquisition,we review three kinds of quantum feedback control strategies:quantum feedback control with measurement,coherent quantum feedback,and quantum feedback control based on cloning and recognition.The first feedback strategy can effectively acquire information,but it destroys the coherence in feedback loop.On the contrary,coherent quantum feedback does not destroy the coherence,but the capability of information acquisition is limited.However,the third feedback scheme gives a compromise between information acquisition and measurement disturbance.
Tracking control of a flexible beam by nonlinear boundary feedback
Bao-Zhu Guo
1995-01-01
Full Text Available This paper is concerned with tracking control of a dynamic model consisting of a flexible beam rotated by a motor in a horizontal plane at the one end and a tip body rigidly attached at the free end. The well-posedness of the closed loop systems considering the dissipative nonlinear boundary feedback is discussed and the asymptotic stability about difference energy of the hybrid system is also investigated.
Tobiyama, M.; Kikutani, E. [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)
1996-08-01
Design and the present status of the bunch by bunch feedback systems for KEKB rings are shown. The detection of the bunch oscillation are made with the phase detection for longitudinal plane, the AM/PM method for transverse plane. Two GHz component of the bunch signal which is extracted with an analog FIR filter is used for the detection. Hardware two-tap FIR filter systems to shift the phase of the oscillation by 90deg will be used for the longitudinal signal processing. The same system will be used with no filtering but with only digital delay for transverse system. The candidate for the kicker and the required maximum power are also estimated. (author)
ATLAS Online Determination and Feedback of the LHC Beam Parameters
Cogan, J; The ATLAS collaboration; Strauss, E; Miller, E
2011-01-01
The High Level Trigger of the ATLAS experiment relies on the precise knowledge of the position, size and orientation of the luminous region produced by the LHC. Moreover, these parameters change significantly even during a single data taking run. We present the challenges, solutions and results for the online luminous region (beam spot) determination, and its monitoring and feedback system in ATLAS. The massively parallel calculation is performed on the trigger farm, where individual processors execute a dedicated algorithm that reconstructs event vertices from the proton-proton collision tracks seen in the silicon trackers. Monitoring histograms from all the cores are sampled and aggregated across the farm every 60 seconds. We describe the process by which a standalone application fetches and fits these distributions, extracting the parameters in real time. When the difference between the nominal and measured beam spot values satisfies threshold conditions, the parameters are published to close the feedback ...
ATLAS Online Determination and Feedback of LHC Beam Parameters
Cogan, J G; The ATLAS collaboration; Bartoldus, R; Miller, D W
2011-01-01
The High Level Trigger of the ATLAS experiment relies on the precise knowledge of the position, size and orientation of the luminous region produced by the LHC. Moreover, these parameters change significantly even during a single data taking run. We present the challenges, solutions and results for the online luminous region (beam spot) determination, and its monitoring and feedback system in ATLAS. The massively parallel calculation is performed on the trigger farm, where individual processors execute a dedicated algorithm that reconstructs event vertices from the proton-proton collision tracks seen in the silicon trackers. Monitoring histograms from all the cores are sampled and aggregated across the farm every 60 seconds. We describe the process by which a standalone application fetches and fits these distributions, extracting the parameters in real time. When the difference between the nominal and measured beam spot values satisfies threshold conditions, the parameters are published to close the feedback ...
Suppression of beam halo-chaos using nonlinear feedback discrete control method
Fang Jin Qing; Chen Guan Rong; Luo Xiao Shu; Weng Jia Qiang
2002-01-01
Based on nonlinear feedback control method, wavelet-based feedback controller as a especial nonlinear feedback function is designed for controlling beam halo-chaos in high-current accelerators of driven clean nuclear power system. PIC simulations show that suppression of beam halo-chaos are realized effectively after discrete control of wavelet-based feed-back is applied to five kinds of the initial proton beam distributions, respectively. The beam halo strength factor is quickly reduced to zero, and other statistical physical quantities of beam halo-chaos are more than doubly reduced. These performed PIC simulation results demonstrate that the developed methods are very effective for control of beam halo-chaos. Potential application of the beam halo-chaos control methods is discussed finally
FEEDBACK REALIZATION OF HAMILTONIAN SYSTEMS
CHENGDaizhan; XIZairong
2002-01-01
This paper investigates the relationship between state feedback and Hamiltonican realization.Firest,it is proved that a completely controllable linear system always has a state feedback state equation Hamiltonian realization.Necessary and sufficient conditions are obtained for it to have a Hamiltonian realization with natural output.Then some conditions for an affine nonlinear system to have a Hamiltonian realization are given.some conditions for an affine nonlinear system to have a Hamiltonian realization are given.For generalized outputs,the conditions of the feedback,keeping Hamiltonian,are discussed.Finally,the admissible feedback controls for generalized Hamiltonian systems are considered.
The Tokamak Fusion Test Reactor employs feedback control systems for four plasma parameters, i.e. for plasma current, for plasma major radius, for plasma vertical position, and for plasma density. The plasma current is controlled by adjusting the rate of change of current in the Ohmic Heating (OH) coil system. Plasma current is continuously sensed by a Rogowski coil and its associated electronics; the error between it and a preprogrammed reference plasma current history is operated upon by a ''proportional-plusintegral-plus-derivative'' (PID) control algorithm and combined with various feedforward terms, to generate compensating commands to the phase-controlled thyristor rectifiers which drive current through the OH coils. The plasma position is controlled by adjusting the currents in Equilibrium Field and Horizontal Field coil systems, which respectively determine the vertical and radial external magnetic fields producing J X B forces on the plasma current. The plasma major radius position and vertical position, sensed by ''B /sub theta/ '' and ''B /sub rho/ '' magnetic flux pickup coils with their associated electronics, are controlled toward preprogrammed reference histories by allowing PID and feedforward control algorithms to generate commands to the EF and HF coil power supplies. Plasma density is controlled by adjusting the amount of gas injected into the vacuum vessel. Time-varying gains are used to combine lineaveraged plasma density measurements from a microwave interferometer plasma diagnostic system with vacuum vessel pressure measurements from ion gauges, with various other measurements, and with preprogrammed reference histories, to determine commands to piezoelectric gas injection valves
FEEDBACK REALIZATION OF HAMILTONIAN SYSTEMS
CHENG Daizhan; XI Zairong
2002-01-01
This paper investigates the relationship between state feedback and Hamiltonian realizatiou. First, it is proved that a completely controllable linear system always has a state feedback state equation Hamiltonian realization. Necessary and sufficient conditions are obtained for it to have a Hamiltonian realization with natural outpnt. Then some conditions for an affine nonlinear system to have a Hamiltonian realization arc given.For generalized outputs, the conditions of the feedback, keeping Hamiltonian, are discussed. Finally, the admissible feedback controls for generalized Hamiltonian systems are considered.
PEP-II RF feedback system simulation
Tighe, R. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)
1996-08-01
A model containing the fundamental impedance of the PEP-II cavity along with the longitudinal beam dynamics and RF feedback system components is in use. It is prepared in a format allowing time-domain as well as frequency-domain analysis and full graphics capability. Matlab and Simulink are control system design and analysis programs (widely available) with many built-in tools. The model allows the use of compiled C-code modules for compute intensive portions. We desire to represent as nearly as possible the components of the feedback system including all delays, sample rates and applicable nonlinearities. (author)
LHC Beam Stability and Feedback Control - Orbit and Energy -
Steinhagen, R J
2007-01-01
This report presents the stability and control of the Large Hadron Collider's (LHC) two beam orbits and their particle momenta using beam-based feedback systems. The LHC, presently being built at CERN, will store, accelerate and provide particle collisions with a maximum particle momentum of 7TeV/c and a nominal luminosity of L = 10^34 cm^â2s^â1. The presence of two beams, with both high intensity as well as high particle energies, requires excellent control of particle losses inside a superconducting environment, which will be provided by the LHC Cleaning and Machine Protection System. The performance and function of this and other systems depends critically on the stability of the beam and may eventually limit the LHC performance. Environmental and accelerator-inherent sources as well as failure of magnets and their power converters may perturb and reduce beam stability and may consequently lead to an increase of particle loss inside the cryogenic mass. In order to counteract these disturbances, c...
Controlling Beam Halo-Chaos via Time-Delayed Feedback
FANG Jin-Qing; WENG Jia-Qiang; ZHU Lun-Wu; LUO Xiao-Shu
2004-01-01
The study of controlling high-current proton beam halo-chaos has become a key concerned issue for many important applications. In this paper, time-delayed feedback control method is proposed for beam halo-chaos. Particle in cell simulation results show that the method is very effective and has some advantages for high-current beam experiments and engineering.
Experimental study of delayed positive feedback control for a flexible beam
无
2011-01-01
Recently, some researches indicate that positive feedback can benefit the control if appropriate time delay is intentionally introduced into control system. However, most work is theoretical one but few are experimental. This paper presents theoretical and experimental studies of delayed positive feedback control technique using a flexible beam as research object. The positive feedback weighting coefficient is designed by using the optimal control method. The available time delay is determined by analyzing ...
Automatic steering of x-ray beams from NSLS insertion devices using closed orbit feedback
By the middle of this year (1989), there will be five insertion devices installed in the NSLS X-ray electron storage ring. X-ray beams from these devices will be stabilized by local automatic steering systems to reduce beam motion at the end of the beamline. Both the position of the source and the direction of the radiation will be controlled using beam position feedback to the closed orbit. Another system will be installed to stabilize the electron orbit for the LEGS Compton backscattering experiment. Each feedback system will employ at least one X-ray beam position detector; some will also utilize rf electron beam position monitors. Analog hardware with a digital interface has been designed and will be installed in the near future. A totally digital realization of the feedback controller is under consideration. 6 refs., 6 figs
ATLAS online determination and feedback of the LHC beam parameters
The High Level Trigger of the ATLAS experiment relies on the precise knowledge of the position, size and orientation of the luminous region produced by the LHC. Moreover, these parameters change significantly even during a single data taking run. We present the challenges, solutions and results for the online luminous region (beam spot) determination, and its monitoring and feedback system in ATLAS. The massively parallel calculation is performed on the trigger farm, where individual processors execute a dedicated algorithm that reconstructs event vertices from the proton-proton collision tracks seen in the silicon trackers. Monitoring histograms from all the cores are sampled and aggregated across the farm every 60 seconds. We describe the process by which a standalone application fetches and fits these distributions, extracting the parameters in real time. When the difference between the nominal and measured beam spot values satisfies threshold conditions, the parameters are published to close the feedback loop. To achieve sharp time boundaries across the event stream that is triggered at rates of several kHz, a special set of data is injected into the event path via the Central Trigger Processor that signals the pending update to the trigger nodes. Finally, we describe the efficient near-simultaneous database access through a proxy fan-out tree, which allows thousands of nodes to fetch the same set of values in a fraction of a second. (authors)
Feedback control of optical beam spatial profiles using thermal lensing
Liu, Zhanwei; Arain, Muzammil A; Williams, Luke; Mueller, Guido; Tanner, David B; Reitze, David H
2013-01-01
A method for active control of the spatial profile of a laser beam using adaptive thermal lensing is described. A segmented electrical heater was used to generate thermal gradients across a transmissive optical element, resulting in a controllable thermal lens. The segmented heater also allows the generation of cylindrical lenses, and provides the capability to steer the beam in both horizontal and vertical planes. Using this device as an actuator, a feedback control loop was developed to stabilize the beam size and position.
Effect of horizontal fast electron beam position feedback on the performance of ESRF beamlines
ESRF is a state of the art third generation synchrotron light source optimized to produce very bright and collimated hard X-ray beams using insertion devices. Instabilities of the electron beam, resulting in source point transverse displacements, spoil these outstanding beam qualities. At the beginning of operation a fast active feedback system was installed to damp the transverse motion of the electron beam in the vertical plane. Recently it became evident that also the relatively smaller horizontal instabilities may have specific detrimental effects on the operation of particularly sensitive beamlines. The dispersive XAS beamline (ID24) was the first to benefit from the activation of a local horizontal feedback. Optimized to perform time-resolved studies and high-pressure experiments, its operation was strongly perturbed. This paper briefly describes the work carried out to identify and solve these problems, presenting the outcome of the implementation of a fast orbit feedback on this beamline
On boundary feedback stabilization of Timoshenko beam with rotor inertia at the tip
Qingxu YAN; Li WAN; Dexing FENG
2004-01-01
The feedback stabilization problem of a nonuniform Timoshenko beam system with rotor inertia at the tip of the beam is studied.First,as a special kind of linear boundary force feedback and moment control is applied to the beam's tip,the strict mathematical treatment,a suitable state Hilbert space is chosen,and the well-poseness of the corresponding closed loop system is proved by using the semigroup theory of bounded linear operators.Then the energy corresponding to the closed loop system is shown to be exponentially stable.Finally,in the special case of uniform beam,some sufficient and necessary conditions for the corresponding closed loop system to be asymptotically stable are derived.
Vogel, E
2004-01-01
For present and future high energy proton accelerators, such as the LHC, transverse feedback systems play an essential role in supplying the physics experiments with high intensity beams at low emittances. We developed a simulation model to study the interaction between beam and transverse feedback system in detail, bunch-by-bunch and turn-by-turn, considering the real technical implementation of the latter. A numerical model is used as the non linear behaviour (saturation) and limited bandwidth of the feedback system, as well as the transient nature at injection and extraction, complicates the analysis. The model is applied to the practical case of the CNGS beam in the SPS accelerator. This beam will be ejected from the SPS in two batches causing residual oscillations by kicker ripples on the second batch. This second batch continues to circulate for 2167 turns after the first batch has been extracted and oscillations are planned to be damped by the feedback system. The model can be extended to examine trans...
Commissioning of the APS real-time orbit feedback system
A unified global and local closed-orbit feedback system has been implemented at the Advanced Photon Source in order to stabilize both particle and photon beams. Beam stability requirements in the band up to 50 Hz are 17 microm in the horizontal plane and 4.4 microm vertically. Orbit feedback algorithms are implemented digitally using multiple digital signal processors, with computing power distributed in 20 VME crates around the storage ring. Each crate communicates with all others via a fast reflective memory network. The system has access to 320 rf beam position monitors together with x-ray beam position monitors in both insertion device and bending magnet beamlines. Up to 317 corrector magnets are available to the system. The global system reduces horizontal rms beam motion at the x-ray source points by more than a factor of two in the frequency band from 10 mHz to 50 Hz
Höfle, Wolfgang
2005-01-01
For existing and future high energy proton accelerators, transverse feedback systems play an essential role in supplying the physics experiments with high intensity beams at low emittances. We developed a simulation model to study the interaction between beam and transverse feedback system in detail, bunch-by-bunch and turn-by-turn, considering the technical implementation at the SPS [1]. A numerical model is used as the non linear behaviour (saturation) and limited bandwidth of the feedback system, as well as the transient nature at injection and extraction, complicates the analysis. The model is applied to the practical case of the CNGS beam [2] in the SPS accelerator. This beam will be ejected from the SPS in two batches causing residual oscillations by kicker ripples on the second batch. This second batch continues to circulate for 50 ms (about 2170 turns) after the first batch has been extracted and oscillations are planned to be damped by the feedback system.
An open-loop state space model of all the major low-level rf feedback control loops is derived. The model has control and state variables for fast-cycling machines to apply modern multivariable feedback techniques. A condition is derived to know when exactly we can cross the boundaries between time-varying and time-invariant approaches for a fast-cycling machine like the Low Energy Booster (LEB). The conditions are dependent on the Q of the cavity and the rate at which the frequency changes with time. Apart from capturing the time-variant characteristics, the errors in the magnetic field are accounted in the model to study the effects on synchronization with the Medium Energy Booster (MEB). The control model is useful to study the effects on beam control due to heavy beam loading at high intensities, voltage transients just after injection especially due to time-varying voltages, instability thresholds created by the cavity tuning feedback system, cross coupling between feedback loops with and without direct rf feedback etc. As a special case we have shown that the model agrees with the well known Pedersen model derived for the CERN PS booster. As an application of the model we undertook a detailed study of the cross coupling between the loops by considering all of them at once for varying time, Q and beam intensities. A discussion of the method to identify the coupling is shown. At the end a summary of the identified loop interactions is presented
Stabilization of Nonuniform Euler-Bernoulli Beam with Locally Distributed Feedbacks
Xian-bing CAO; Qing-xu YAN
2012-01-01
In this article,we study the stabilization problem of a nonuniform Euler-Bernoulli beam with locally distributed feedbacks.Firstly,using the semi-group theory,we establish the well-posedness of the associated closed loop system.Then by proving the uniqueness of the solution of a related ordinary differential equations,we derive the asymptotic stability of the closed loop system. Finally,by means of the piecewise frequency domain multiplier method,we prove that the corresponding closed loop system can be exponentially stabilized by only one of the two distributed feedback controls proposed in this paper.
Kwabena A. Konadu
2013-01-01
Full Text Available High-precision positioning of laser beams has been a great challenge in industry due to inevitable existence of noise and disturbance. The work presented in this study addresses this problem by employing two different control strategies: Proportional Integral Derivative (PID control and state feedback control with an observer. The control strategies are intended to stabilize the position of a laser beam on a Position Sensing Device (PSD located on a Laser Beam Stabilization (or, laser beam system system. The laser beam system consists of a laser source, a Fast Steering Mirror (FSM, a PSD and a vibrating platform to generate active disturbance. The traditional PID controller is widely used in industry due to its satisfactory performance, various available tuning methods and relatively straightforward design processes. However, design of filters to obtain the derivative signal is challenging and can unexpectedly distort the dynamics of the system being controlled. As an alternative, use of an Observer-Based State Feedback (OBSF method is proposed and implemented. The state-space model of the laser beam system is utilized and an observer is applied to estimate the state of the system, since all the state variables cannot be measured directly. For observer design, eigenvalue assignment and optimal design methods are used and compared in terms of system performance. Also a comparative analysis between the PID and OBSF controllers is provided. Simulations and experimental results show that the OBSF controller rejects disturbance better and has a simpler design procedure.
Multimedia Feedback Systems for Engineering
Gladwell, S.; Gottlieb, E.J.; McDonald, M.J.; Slutter, C.L.
1998-12-15
The World Wide Web has become a key tool for information sharing. Engineers and scientists are finding that the web is especially suited to publishing the graphical, multi-layered information that is typical of their work. Web pages are easier to distribute than hardcopy. Web movies have become more accessible, in many offices, than videos. Good VRML viewing software, bundled with most new PCs, has sufficient power to support many engineering needs. In addition to publishing information science and engineering has an important tradition of peer and customer review. Reports, drawings and graphs are typically printed, distributed, reviewed, marked up, and returned to the author. Adding review comments to paper is easy. When, however, the information is in electronic form, this ease of review goes away. It's hard to write on videos. It's even harder to write comments on animated 3D models. These feedback limitations reduce the value of the information overall. Fortunately, the web can also be a useful tool for collecting peer and customer review information. When properly formed, web reports, movies, and 3D animations can be readily linked to review notes. This paper describes three multimedia feed-back systems that Sandia National Laboratories has developed to tap that potential. Each system allows people to make context-sensitive comments about specific web content and electronically ties the comments back to the web content being referenced. The fuel system ties comments to specific web pages, the second system ties the comments to specific frames of digital movies, and the third ties the comments to specific times and viewpoints within 3D animations. In addition to the technologies, this paper describes how they are being used to support intelligent machine systems design at Sandia.
Applications of Feedback Control in Quantum Systems
Jacobs, Kurt
2006-01-01
We give an introduction to feedback control in quantum systems, as well as an overview of the variety of applications which have been explored to date. This introductory review is aimed primarily at control theorists unfamiliar with quantum mechanics, but should also be useful to quantum physicists interested in applications of feedback control. We explain how feedback in quantum systems differs from that in traditional classical systems, and how in certain cases the results from modern optim...
A prototype fast feedback system for energy lock at CEBAF
Chowdhary, M.; Krafft, G.A.; Shoaee, H.; Simrock, S.N.; Watson, W.A.
1995-12-31
The beam energy at CEBAF must be controlled accurately against phase and gradient fluctuations in RF cavities in order to achieve a 2.5 {times} 10{sup {minus}5} relative energy spread. A prototype fast feedback system based on the concepts of Modern Control Theory has been implemented in the CEBAF control system to function as an energy lock. Measurements performed during the pulsed mode operations indicate presence of noise components at 4 Hz and 12 Hz on beam energy. This fast feedback prototype operates at 60 Hz rate and is integrated with EPICS. This paper describes the implementation of the fast feedback prototype, and operational experience with this system at CEBAF. 5 refs., 3 figs.
Survey of Digital Feedback Systems in High Current Storage Rings
In the last decade demand for brightness in synchrotron light sources and luminosity in circular colliders led to construction of multiple high current storage rings. Many of these new machines require feedback systems to achieve design stored beam currents. In the same time frame the rapid advances in the technology of digital signal processing allowed the implementation of these complex feedback systems. In this paper I concentrate on three applications of feedback to storage rings: orbit control in light sources, coupled-bunch instability control, and low-level RF control. Each of these applications is challenging in areas of processing bandwidth, algorithm complexity, and control of time-varying beam and system dynamics. I will review existing implementations as well as comment on promising future directions
Dikansky, N.; Nagaitsev, S.; Parkhomchuk, V.
1997-09-01
The high energy electron cooling requires a very cold electron beam. Thus, the electron beam focusing system is very important for the performance of electron cooling. A system with and without longitudinal magnetic field is presented for discussion. Interaction of electron beam with the vacuum chamber as well as with the background ions and stored antiprotons can cause the coherent electron beam instabilities. Focusing system requirements needed to suppress these instabilities are presented.
Feedback system to stabilize accelerating field in the UNK
To stabilize accelerating field in the UNK proton synchrotron, an HF feedback system is proposed with one-turn time delay and two loops of automatic voltage control having unequal gains. The system would handle a pair of crucial effects caused by the fundamental mode of the accelerating cavities: heavy transient beam loading, and strong dipole and quadrupole longitudinal instabilities of the beam. The beam-cavity coupling impedance near HF is shown to be split up by the feedback loops into a 2 x 2 matrix. Its elements are used to estimate the residual error of the voltage across the accelerating gap from its nominal, the instability driving impedances near HF, and the net current required to drive an HF amplifier. A new global parameters to outline technical contours of the system are evaluated. 8 refs., 8 figs
ON FEEDBACK CONTROL OF DELAYED CHAOTIC SYSTEM
李丽香; 彭海朋; 卢辉斌; 关新平
2001-01-01
In this paper two different types of feedback control technique are discussed: the standard feedback control and the time-delay feedback control which have been successfully used in many control systems. In order to understand to what extent the two different types of control technique are useful in delayed chaotic systems, some analytic stabilization conditions for chaos control from the two types of control technique are derived based on Lyapunov stabilization arguments. Similarly, we discuss the tracking problem by applying the time-delay feedback control. Finally, numerical examples are provided.
Advanced information feedback in intelligent traffic systems.
Wang, Wen-Xu; Wang, Bing-Hong; Zheng, Wen-Chen; Yin, Chuan-Yang; Zhou, Tao
2005-12-01
The optimal information feedback is very important to many socioeconomic systems like stock market and traffic systems aiming to make full use of resources. As to traffic flow, a reasonable real-time information feedback can improve the urban traffic condition by providing route guidance. In this paper, the influence of a feedback strategy named congestion coefficient feedback strategy is introduced, based on a two-route scenario in which dynamic information can be generated and displayed on the board to guide road users to make a choice. Simulation results adopting this optimal information feedback strategy have demonstrated high efficiency in controlling spatial distribution of traffic patterns compared with the other two information feedback strategies, i.e., travel time and mean velocity. PMID:16486093
Feedbacks in Human-Landscape Systems
Chin, Anne; Florsheim, Joan L.; Wohl, Ellen; Collins, Brian D.
2014-01-01
This article identifies key questions and challenges for geomorphologists in investigating coupled feedbacks in human-landscape systems. While feedbacks occur in the absence of human influences, they are also altered by human activity. Feedbacks are a key element to understanding human-influenced geomorphic systems in ways that extend our traditional approach of considering humans as unidirectional drivers of change. Feedbacks have been increasingly identified in Earth-environmental systems, with studies of coupled human-natural systems emphasizing ecological phenomena in producing emerging concepts for social-ecological systems. Enormous gaps or uncertainties in knowledge remain with respect to understanding impact-feedback loops within geomorphic systems with significant human alterations, where the impacted geomorphic systems in turn affect humans. Geomorphology should play an important role in public policy by identifying the many diffuse and subtle feedbacks of both local- and global-scale processes. This role is urgent, while time may still be available to mitigate the impacts that limit the sustainability of human societies. Challenges for geomorphology include identification of the often weak feedbacks that occur over varied time and space scales ranging from geologic time to single isolated events and very short time periods, the lack of available data linking impact with response, the identification of multiple thresholds that trigger feedback mechanisms, the varied tools and metrics needed to represent both physical and human processes, and the need to collaborate with social scientists with expertise in the human causes of geomorphic change, as well as the human responses to such change.
Development of the orbit feedback system for the VSX ring
An orbit feedback system will be installed in the VSX ring to stabilize the photon beam. The new COD correction method, the eigenvector method with constraints, is adopted for calculation of the steering-magnet currents. A computer simulation shows that the new method can tightly fix the beam positions at insertion devices, correcting the whole closed orbit globally with almost the same performance as the ordinary eigenvector method. A test VME unit including DSP and shared memory boards is being developed for the fast feedback control and its performance test shows that the total feedback time is less than 1 ms (875 μs) except for the network and VME-bus transfer times related to the shared memory board
Energy feedback system for the SSRL Injector linac
The SSRL Injector microwave gun, linac, and booster were commissioned last year. For efficient injection into the booster the linac beam energy must be stable to within about 1%. Unfortunately, fluctuations in the line voltage supplying the unregulated klystron modulators cause fluctuations in the linac beam energy, thus making the operation of the booster potentially very difficult. Without any corrections, the linac energy may drift by as much as one percent per minute or it may jump suddenly by one percent. Fortunately, the linac beam energy can be kept close to the desired value by using feedback on the low level controls of the klystrons feeding two of the linac sections. The energy of the linac is sampled at a beam position monitor (BPM) downstream of the first magnet following the linac. The feedback loop is closed using a low-pass filter that filters out noise from the BPM processing electronics. The feedback is implemented as a computer program (energy feedback) written in C for the SSRL Injector control system, and is robust against various fault conditions, as a result of the many changes and adjustments suggested by the commissioning team who are mentioned in the acknowledgements
A patent is claimed for the invention of a beam alignment system. The aim of the invention is the obtention of an accurate monitoring of the beam position and direction. It is of great interest in the nuclear industry. The invention can be applied in an infrared laser beam for welding operations. An auxiliar radiation source is incorporated to the device. The system's configuration allows a simultaneous and separated utilisation of two beams. The description and the design of the proposed system are provided
Stability Analysis of Nonlinear Feedback Control Methods for Beam Halo-chaos
WANGZhong-sheng; FANGJin-qing; CHENGuan-rong
2003-01-01
Control of beam halo-chaos has been a more challenge subject in recent years, in which nonlinear feedback method for beam halo-chaos has been developed for control of beam halo-chaos in high-current proton linear accelerators. However, stability analysis of nonlinear feedback control methods for beam halo-chaos has still been an open and important topic in this field. In this letter.
Prediction feedback in intelligent traffic systems
Chuan-Fei, Dong; Guan-Wen, Wang; Xiao-Yan, Sun; Bing-Hong, Wang
2009-01-01
The optimal information feedback has a significant effect on many socioeconomic systems like stock market and traffic systems aiming to make full use of resources. In this paper, we studied dynamics of traffic flow with real-time information provided and the influence of a feedback strategy named prediction feedback strategy is introduced, based on a two-route scenario in which dynamic information can be generated and displayed on the board to guide road users to make a choice. Our model incorporates the effects of adaptability into the cellular automaton models of traffic flow and simulation results adopting this optimal information feedback strategy have demonstrated high efficiency in controlling spatial distribution of traffic patterns compared with the other three information feedback strategies, i.e., vehicle number and flux.
Augmenting Environmental Interaction in Audio Feedback Systems
Seunghun Kim
2016-04-01
Full Text Available Audio feedback is defined as a positive feedback of acoustic signals where an audio input and output form a loop, and may be utilized artistically. This article presents new context-based controls over audio feedback, leading to the generation of desired sonic behaviors by enriching the influence of existing acoustic information such as room response and ambient noise. This ecological approach to audio feedback emphasizes mutual sonic interaction between signal processing and the acoustic environment. Mappings from analyses of the received signal to signal-processing parameters are designed to emphasize this specificity as an aesthetic goal. Our feedback system presents four types of mappings: approximate analyses of room reverberation to tempo-scale characteristics, ambient noise to amplitude and two different approximations of resonances to timbre. These mappings are validated computationally and evaluated experimentally in different acoustic conditions.
Feedbacks in human-landscape systems
Chin, Anne
2015-04-01
As human interactions with Earth systems intensify in the "Anthropocene", understanding the complex relationships among human activity, landscape change, and societal responses to those changes is increasingly important. Interdisciplinary research centered on the theme of "feedbacks" in human-landscape systems serves as a promising focus for unraveling these interactions. Deciphering interacting human-landscape feedbacks extends our traditional approach of considering humans as unidirectional drivers of change. Enormous challenges exist, however, in quantifying impact-feedback loops in landscapes with significant human alterations. This paper illustrates an example of human-landscape interactions following a wildfire in Colorado (USA) that elicited feedback responses. After the 2012 Waldo Canyon Fire, concerns for heightened flood potential and debris flows associated with post-fire hydrologic changes prompted local landowners to construct tall fences at the base of a burned watershed. These actions changed the sediment transport regime and promoted further landscape change and human responses in a positive feedback cycle. The interactions ultimately increase flood and sediment hazards, rather than dampening the effects of fire. A simple agent-based model, capable of integrating social and hydro-geomorphological data, demonstrates how such interacting impacts and feedbacks could be simulated. Challenges for fully capturing human-landscape feedback interactions include the identification of diffuse and subtle feedbacks at a range of scales, the availability of data linking impact with response, the identification of multiple thresholds that trigger feedback mechanisms, and the varied metrics and data needed to represent both the physical and human systems. By collaborating with social scientists with expertise in the human causes of landscape change, as well as the human responses to those changes, geoscientists could more fully recognize and anticipate the coupled
Orbit correction algorithm for SSRF fast orbit feedback system
LIU Ming; YIN Chongxian; LIU Dekang
2009-01-01
A fast orbit feedback system is designed at SSRF to suppress beam orbit disturbance within sub-micron in the bandwidth up to 100 Hz.The SVD (Singular value decomposition) algorithm is applied to calculate the inverse response matrix in global orbit correction.The number of singular eigenvalues will influence orbit noise suppression and corrector strengths.The method to choose singular eigenvalue rejection threshold is studied in this paper,and the simulation and experiment results are also presented.
A tracking system with space virtual feedback
Zheng MAO; Xiaojun QU; Fuling WEI; Yali WANG
2008-01-01
In this paper,a tracking system with space virtual feedback(SVF)is presented.The whole tracking system is closed by the space virtual feedback line that is the line of sight(LOS),but the parts in the system,such as the tracking subsystem and the servo subsystem.are in the state of open-loop.Because the SVF tracking model is used.the correcting loops can be removed in this system architecture.So the tracking speed and accuracy of the system are greatly improved.
Real time global orbit feedback system
Stability of the electron orbit is essential for the utilization of a low emittance storage ring as high brightness radiation source. For an individual user, the required orbit stability can be achieved by a local bump feedback system. However, to install local bump feedback systems for every beamline is both costly and impractical. The coupling between different local bumps may introduce instability, and there may not be enough space for the large number of trim coils required. Here the authors discuss an approach for improving the stability of the closed orbit, by implementing a feedback system based upon harmonic analysis of the orbit movements and the correction magnetic fields. This harmonic feedback system corrects the Fourier components of the orbit nearest to the betatron tune, an approach which yields an orbit whose stability is sufficient for most experiments. The needs of the experiments requiring the tightest orbit tolerances can still be dealt with by additional local orbit feedback systems. Harmonic orbit correction is an effective technique for eliminating global orbit distortion in storage rings resulting from inevitable magnetic field errors distributed around the ring. The their knowledge, this approach has not previously been applied dynamically to eliminate orbit fluctuations arising from time varying magnetic field errors. They have developed a harmonic feedback system which is implemented on a real time basis using relatively simple electronics. The Fourier analysis is done by a simple linear analog network. The input voltages are proportional to the orbit displacements at the detectors, and in real time the output voltages are proportional to the desired Fourier harmonic coefficients. The feedback does not force the displacement to be zero at the detectors, but forces the coefficients of a few harmonics nearest the betatron tune to vanish
Adaptive feedback linearization of nonlinear SISO systems
Gonzales, R. I.; Duarte-Mermoud, M. A.; Zagalak, Petr
New Haven : Yale University, 2003, s. 160-169. [Workshop on Adaptive and Learning Systems /12./. Yale (US), 28.05.2003-30.05.2003] R&D Projects: GA ČR GA102/02/0204 Institutional research plan: CEZ:AV0Z1075907 Keywords : adaptive linearization * nonlinear systems * feedback linearization Subject RIV: BC - Control Systems Theory
Simulation and analysis of rf feedback systems on the SLC damping rings
The rf system of the SLC Damping Rings has evolved since tighter tolerances on beam stability are encountered as beam intensities are increased. There are now many feedback systems controlling the phase and amplitude of the rf, the phase of the beam, and the tune of the cavity. The bandwidths of the feedback loops range from several MHz to compensate for beam loading to a few Hz for the cavity tuners. To improve our understanding of the interaction of these loops and verify the expected behavior, we have simulated their behavior using computer models. A description of the models and the first results are discussed
Mimicking the cochlear amplifier in a cantilever beam using nonlinear velocity feedback control
The mammalian cochlea exhibits a nonlinear amplification which allows mammals to detect a large range of sound pressure levels while maintaining high frequency sensitivity. This work seeks to mimic the cochlea’s nonlinear amplification in a mechanical system. A nonlinear, velocity-based feedback control law is applied to a cantilever beam with piezoelectric actuators. The control law reduces the linear viscous damping of the system while introducing a cubic damping term. The result is a system which is positioned close to a Hopf bifurcation. Modelling and experimental results show that the beam with this control law undergoes a one-third amplitude scaling near the resonance frequency and an amplitude-dependent bandwidth. Both behaviors are characteristic of data obtained from the mammalian cochlea. This work could provide insight on the biological cochlea while producing bio-inspired sensors with a large dynamic range and sharp frequency sensitivity. (papers)
Developing 360 degree feedback system for KINS
Han, In Soo; Cheon, B. M.; Kim, T. H.; Ryu, J. H. [Chungman National Univ., Daejeon (Korea, Republic of)
2003-12-15
This project aims to investigate the feasibility of a 360 degree feedback systems for KINS and to design guiding rules and structures in implementing that systems. Literature survey, environmental analysis and questionnaire survey were made to ensure that 360 degree feedback is the right tool to improve performance in KINS. That review leads to conclusion that more readiness and careful feasibility review are needed before implementation of 360 degree feedback in KINS. Further the project suggests some guiding rules that can be helpful for successful implementation of that system in KINS. Those include : start with development, experiment with one department, tie it to a clear organization's goal, train everyone involve, make sure to try that system in an atmosphere of trust.
Developing 360 degree feedback system for KINS
This project aims to investigate the feasibility of a 360 degree feedback systems for KINS and to design guiding rules and structures in implementing that systems. Literature survey, environmental analysis and questionnaire survey were made to ensure that 360 degree feedback is the right tool to improve performance in KINS. That review leads to conclusion that more readiness and careful feasibility review are needed before implementation of 360 degree feedback in KINS. Further the project suggests some guiding rules that can be helpful for successful implementation of that system in KINS. Those include : start with development, experiment with one department, tie it to a clear organization's goal, train everyone involve, make sure to try that system in an atmosphere of trust
Stability Analysis of Some Nonlinear Feedback Control Methods for Beam Halo-Chaos Suppression
FANG Jin-Qing; WANG Zhong-Sheng; CHEN Guan-Rong
2004-01-01
Control of beam halo-chaos has been a very challenging subject for research in recent years, in which some nonlinear feedback methods have been developed for suppression of beam halo-chaos in high-current proton linear accelerators. However, stability analysis of such successful nonlinear feedback control methods has not yet been rigorously carried out, which remains an important open topic in the field. In this letter, we present a rigorous mathematical analysis of several nonlinear feedback control methods that are applied to control beam halo-chaos with great success on simulations.
Stability Analysis of Some Nonlinear Feedback Control Methods for Beam Halo-ChaosSuppression
FANGJin-Qing; WANGZhong-Sheng; CHENGuan-Rong
2004-01-01
Control of beam halo-chaos has been a very challenging subject for research in recent years, in which some nonlinear feedback methods have been developed for suppression of beam halo-chaos in high-current proton linear accelerators. However, stability analysis of such successful nonlinear feedback control methods has not yet been rigorously carried out, which remains an important open topic in the field. In this letter, we present a rigorous mathematical analysis of several nonlinear feedback control methods that are applied to control beam halo-chaos with great success on simulations.
Phase and amplitude feedback control system for the Los Alamos free-electron laser
Phase and amplitude feedback control systems for the Los Alamos free-electron laser (FEL) are described. Beam-driven voltages are very high in the buncher cavity because the electron gun is pulsed at the fifth subharmonic of the buncher resonant frequency. The high beam loading necessitated a novel feedback and drive configuration for the buncher. A compensation cirucit has been added to the gun/driver system to reduce observed drift. Extremely small variations in the accelerator gradients had dramatic effects on the laser output power. These problems and how they were solved are described and plans for improvements in the feedback control system are discussed. 5 refs., 7 figs
Tomizawa, H; Dewa, H; Hanaki, H; Kobayashi, T; Mizuno, A; Suzuki, S; Taniuchi, T; Yanagida, K
2004-01-01
The ideal spatial and temporal profiles of a shot-by-shot single laser pulse are essential to suppress the emittance growth of the electron beam from a photo-cathode rf gun. We have been developing highly qualified UV-laser pulse as a light source of the rf gun for an injector candidate of future light sources. The gun cavity is a single-cell pillbox, and the copper inner wall is used as a photo cathode. The electron beam was accelerated up to 4.1 MeV at the maximum electric field on the cathode surface of 175 MV/m. For emittance compensation, two solenoid coils were used. As the first test run, with a microlens array as a simple spatial shaper, we obtained a minimum emittance value of 2 π·mm·mrad with a beam energy of 3.1 MeV, holding its charge to 0.1 nC/bunch. In the next test run, we prepared a deformable mirror for spatial shaping, and a spatial light modulator based on fused-silica plates for temporal shaping. We applied the both adaptive optics to automatically shape the bot...
Diversity in School Performance Feedback Systems
Verhaeghe, Goedele; Schildkamp, Kim; Luyten, Hans; Valcke, Martin
2015-01-01
As data-based decision making is receiving increased attention in education, more and more school performance feedback systems (SPFSs) are being developed and used worldwide. These systems provide schools with data on their functioning. However, little research is available on the characteristics of the different SPFSs. Therefore, this study…
Exact stability chart of an elastic beam subjected to delayed feedback
Zhang, Li; Stepan, Gabor
2016-04-01
The stability of an elastic beam is studied when the beam is subjected to a longitudinal force governed by a feedback loop. The setup of the simplified mechanical model is motivated by a basic problem of electroacoustics. The corresponding governing equation is the 1D wave equation with delayed boundary conditions. By means of the D'Alembert solution, the system can be transformed into a delay differential equation of neutral type that includes two time delays. The intricate stability chart is constructed analytically in the parameter plane of the gain parameter and the ratio of the time delays. The complete chart extends the numerical results of the literature, while it also draws attention to the numerical difficulties of finite degree of freedom approximations and to the extreme sensitivity of the dynamics with respect to the time delay parameters of the system.
Novel Reduced-Feedback Wireless Communication Systems
Shaqfeh, Mohammad Obaidah
2011-11-20
Modern communication systems apply channel-aware adaptive transmission techniques and dynamic resource allocation in order to exploit the peak conditions of the fading wireless links and to enable significant performance gains. However, conveying the channel state information among the users’ mobile terminals into the access points of the network consumes a significant portion of the scarce air-link resources and depletes the battery resources of the mobile terminals rapidly. Despite its evident drawbacks, the channel information feedback cannot be eliminated in modern wireless networks because blind communication technologies cannot support the ever-increasing transmission rates and high quality of experience demands of current ubiquitous services. Developing new transmission technologies with reduced-feedback requirements is sought. Network operators will benefit from releasing the bandwidth resources reserved for the feedback communications and the clients will enjoy the extended battery life of their mobile devices. The main technical challenge is to preserve the prospected transmission rates over the network despite decreasing the channel information feedback significantly. This is a noteworthy research theme especially that there is no mature theory for feedback communication in the existing literature despite the growing number of publications about the topic in the last few years. More research efforts are needed to characterize the trade-off between the achievable rate and the required channel information and to design new reduced-feedback schemes that can be flexibly controlled based on the operator preferences. Such schemes can be then introduced into the standardization bodies for consideration in next generation broadband systems. We have recently contributed to this field and published several journal and conference papers. We are the pioneers to propose a novel reduced-feedback opportunistic scheduling scheme that combines many desired features
Kwabena A. Konadu; Sun Yi; Wonchang Choi; Taher Abu-Lebdeh
2013-01-01
High-precision positioning of laser beams has been a great challenge in industry due to inevitable existence of noise and disturbance. The work presented in this study addresses this problem by employing two different control strategies: Proportional Integral Derivative (PID) control and state feedback control with an observer. The control strategies are intended to stabilize the position of a laser beam on a Position Sensing Device (PSD) located on a Laser Beam Stabilization (or, laser beam ...
Distributed delays stabilize neural feedback systems
Meyer, Ulrike; Chakrabarty, Saurish; Brandt, Sebastian F; Luksch, Harald; Wessel, Ralf
2007-01-01
We consider the effect of distributed delays in neural feedback systems. The avian optic tectum is reciprocally connected with the nucleus isthmi. Extracellular stimulation combined with intracellular recordings reveal a range of signal delays from 4 to 9 ms between isthmotectal elements. This observation together with prior mathematical analysis concerning the influence of a delay distribution on system dynamics raises the question whether a broad delay distribution can impact the dynamics of neural feedback loops. For a system of reciprocally connected model neurons, we found that distributed delays enhance system stability in the following sense. With increased distribution of delays, the system converges faster to a fixed point and converges slower toward a limit cycle. Further, the introduction of distributed delays leads to an increased range of the average delay value for which the system's equilibrium point is stable. The enhancement of stability with increasing delay distribution is caused by the int...
This paper investigates the active vibration control of clamp beams using positive position feedback (PPF) controllers with a sensor/ moment pair actuator. The sensor/moment pair actuator which is the non-collocated configuration leads to instability of the control system when using the direct velocity feedback (DVFB) control. To alleviate the instability problem, a PPF controller is considered in this paper. A parametric study of the control system with PPF controller is first conducted to characterize the effects of the design parameters (gain and damping ratio in this paper) on the stability and performance. The gain of the controller is found to affect only the relative stability. Increasing the damping ratio of the controller slightly improves the stability condition while the performance gets worse. In addition, the higher mode tuned PPF controller affects the system response at the lower modes significantly. Based on the characteristics of PPF controllers, a multi-mode controllable SISO PPF controller is then considered and tuned to different modes (in this case, three lowest modes) numerically and experimentally. The multi-mode PPF controller can be achieved to have a high gain margin. Moreover, it reduces the vibration of the beam significantly. The vibration levels at the tuned modes are reduced by about 11 dB
Robust synchronization of chaotic systems via feedback
Femat, Ricardo [IPICYT, San Luis Potosi (Mexico). Dept. de Matematicas Aplicadas; Solis-Perales, Gualberto [Universidad de Guadalajara, Centro Univ. de Ciencias Exactas e Ingenierias (Mexico). Div. de Electronica y Computacion
2008-07-01
This volume includes the results derived during last ten years about both suppression and synchronization of chaotic -continuous time- systems. Along this time, the concept was to study how the intrinsic properties of dynamical systems can be exploited to suppress and to synchronize the chaotic behaviour and what synchronization phenomena can be found under feedback interconnection. A compilation of these findings is described in this book. This book shows a perspective on synchronization of chaotic systems. (orig.)
Beam systems without failures - What can be done?
The beam dumps at 3.5 TeV triggered by interlocks not related to the magnet powering are discussed. This concerns the systems like the RF, the transverse feedbacks, beam instrumentation, beam dumping system, collimators and control systems. An analysis of the reasons of these dumps is presented together with a possible strategy to mitigate the effect of these failures. It is very important to notice that no system has been identified to have any structural problem
Target and orbit feedback simulations of a muSR beam line at BNL
MacKay, W. [Brookhaven National Lab. (BNL), Upton, NY (United States); Blaskiewicz, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Fischer, W. [Brookhaven National Lab. (BNL), Upton, NY (United States); Pile, P. [Brookhaven National Lab. (BNL), Upton, NY (United States)
2015-07-28
Well-polarized positive surface muons are a tool to measure the magnetic properties of materials since the precession rate of the spin can be determined from the observation of the positron directions when the muons decay. For a dc beam an ideal µSR flux for surface µ^{+} should be about 40 kHz/mm^{2}. In this report we show how this flux could be achieved in a beam line using the AGS complex at BNL for a source of protons. We also determined that an orbit feedback system with a pair of thin silicon position monitors and kickers would miss the desired flux by at least an order of magnitude, even with perfect time resolution and no multiple scattering.
Development of beam current control system in RF-knockout slow extraction
Mizushima, K., E-mail: mizshima@nirs.go.jp [Department of Accelerator and Medical Physics, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Graduate School of Science and Technology, Chiba University, Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Sato, S.; Shirai, T.; Furukawa, T.; Katagiri, K.; Takeshita, E.; Iwata, Y.; Himukai, T.; Noda, K. [Department of Accelerator and Medical Physics, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)
2011-12-15
A raster scanning method has been developed for cancer therapy at NIRS-HIMAC. This method requires a high-accuracy beam current control and fast beam-on/off switching. We have developed a feedback control system of the beam current with the RF-knockout slow extraction method. The system has allowed a stable response to beam-on/off switching using a feedback control delay function with a beam-current ripple of 7%.
The Neutral Beam (NB) system for the International Thermonuclear Experimental Reactor (ITER) has reached a high degree of integration with the tokamak and with the rest of the plant. Operational requirements and maintainability have been considered in the design. The paper considers the integration with the tokamak, discusses design improvements which appear necessary and finally notes R and D progress in key areas. (author)
Electron beam processing system
Electron beam Processing Systems (EPS) are used as useful and powerful tools in many industrial application fields such as the production of cross-linked wire, rubber tire, heat shrinkable film and tubing, curing, degradation of polymers, sterilization and environmental application. In this paper, the feature and application fields, the selection of machine ratings and safety measures of EPS will be described. (author)
Terrestrial biogeochemical feedbacks in the climate system
Arneth, A.; Harrison, S. P.; Zaehle, S.; Tsigaridis, K.; Menon, S.; Bartlein, P. J.; Feichter, J.; Korhola, A.; Kulmala, M.; O'Donnell, D.; Schurgers, G.; Sorvari, S.; Vesala, T.
2010-08-01
The terrestrial biosphere is a key regulator of atmospheric chemistry and climate. During past periods of climate change, vegetation cover and interactions between the terrestrial biosphere and atmosphere changed within decades. Modern observations show a similar responsiveness of terrestrial biogeochemistry to anthropogenically forced climate change and air pollution. Although interactions between the carbon cycle and climate have been a central focus, other biogeochemical feedbacks could be as important in modulating future climate change. Total positive radiative forcings resulting from feedbacks between the terrestrial biosphere and the atmosphere are estimated to reach up to 0.9 or 1.5 W m-2 K-1 towards the end of the twenty-first century, depending on the extent to which interactions with the nitrogen cycle stimulate or limit carbon sequestration. This substantially reduces and potentially even eliminates the cooling effect owing to carbon dioxide fertilization of the terrestrial biota. The overall magnitude of the biogeochemical feedbacks could potentially be similar to that of feedbacks in the physical climate system, but there are large uncertainties in the magnitude of individual estimates and in accounting for synergies between these effects.
Monitoring Digital Closed-Loop Feedback Systems
Katz, Richard; Kleyner, Igor
2011-01-01
A technique of monitoring digital closed-loop feedback systems has been conceived. The basic idea is to obtain information on the performances of closed-loop feedback circuits in such systems to aid in the determination of the functionality and integrity of the circuits and of performance margins. The need for this technique arises as follows: Some modern digital systems include feedback circuits that enable other circuits to perform with precision and are tolerant of changes in environment and the device s parameters. For example, in a precision timing circuit, it is desirable to make the circuit insensitive to variability as a result of the manufacture of circuit components and to the effects of temperature, voltage, radiation, and aging. However, such a design can also result in masking the indications of damaged and/or deteriorating components. The present technique incorporates test circuitry and associated engineering-telemetry circuitry into an embedded system to monitor the closed-loop feedback circuits, using spare gates that are often available in field programmable gate arrays (FPGAs). This technique enables a test engineer to determine the amount of performance margin in the system, detect out of family circuit performance, and determine one or more trend(s) in the performance of the system. In one system to which the technique has been applied, an ultra-stable oscillator is used as a reference for internal adjustment of 12 time-to-digital converters (TDCs). The feedback circuit produces a pulse-width-modulated signal that is fed as a control input into an amplifier, which controls the circuit s operating voltage. If the circuit s gates are determined to be operating too slowly or rapidly when their timing is compared with that of the reference signal, then the pulse width increases or decreases, respectively, thereby commanding the amplifier to increase or reduce, respectively, its output level, and "adjust" the speed of the circuits. The nominal
Beam Instrumentation Using BPM System of the SPring-8 Linac
Yanagida, K; Dewa, H; Hanaki, H; Kobayashi, T; Mizuno, A; Suzuki, S; Taniuchi, T; Tomizawa, H
2004-01-01
A beam position monitor (BPM) system of the SPring-8 linac has been operated since 2002. The following upgrade programs have been carried out during this period: The BPMs were installed in the linac's dispersive sections. A synchronized accumulation of beam position data into the database system started. A feedback control of steering magnets for beam position stabilization has been under development. In this conference the authors report a performance of the BPM system, and discuss its usefulness for beam diagnostics, machine diagnostics and beam stabilization.
Assessing biosphere feedbacks on Earth System Processes
McElwain, Jennifer
2016-04-01
The evolution and ecology of plant life has been shaped by the direct and indirect influence of plate tectonics. Climatic change and environmental upheaval associated with the emplacement of large igneous provinces have triggered biosphere level ecological change, physiological modification and pulses of both extinction and origination. This talk will investigate the influence of large scale changes in atmospheric composition on plant ecophysiology at key intervals of the Phanerozoic. Furthermore, I will assess the extent to which plant ecophysiological response can in turn feedback on earth system processes such as the global hydrological cycle and biogeochemical cycling of nitrogen and carbon. Palaeo-atmosphere simulation experiments, palaeobotanical data and recent historical (last 50 years) data-model comparison will be used to address the extent to which plant physiological responses to atmospheric CO2 can modulate global climate change via biosphere level feedback.
Optimal Feedback Systems with Analogue Adaptive Transmitters
Platonov, Anatoliy
2010-01-01
The paper presents original approach to concurrent optimization of the transmitting and receiving parts of adaptive communication systems (CS) with feedback channels. The results of research show a possibility and the way of designing the systems transmitting the signals with a bit rate equal to the capacity of the forward channel under given bit-error rate (BER). The results of work can be used for design of different classes of high-efficient low energy/size/cost CS, as well as allow further development and extension.
Adaptive feedback beam shaping of the CO2 welding laser
Jedlička, Petr; Mrňa, L.; Šarbort, M.; Řeřucha, Šimon
Bellingham: SPIE, 2010, 77890V: 1-8. ISBN 978-0-8194-8285-3. [Laser Beam Shaping XI. San Diego (US), 02.08.2010] R&D Projects: GA MPO 2A-3TP1/113 Institutional research plan: CEZ:AV0Z20650511 Keywords : laser beam welding * adaptive optics * laser welding control * light emission monitoring Subject RIV: BH - Optics, Masers, Lasers
Control of beam halo-chaos by delayed self-controlling feedback
Zhu Lun Wu; Gao Yuan; Fang Jin Qing
2002-01-01
The delayed self-controlling feedback method is used to control beam halo-chaos in high-intensity accelerator effectively under five different initial distributions of protons. A brief theoretic analysis is presented. This method, considering its linear controller and weak feedback, has the advantage in technology realizability and cost saving. It cna be a good reference in the application to high-intensity accelerators
Simulations of the TESLA Linear Collider with a Fast Feedback System
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.
Synchronization between two different chaotic systems with nonlinear feedback control
Lü Ling; Guo Zhi-An; Zhang Chao
2007-01-01
This paper presents chaos synchronization between two different chaotic systems by using a nonlinear controller, in which the nonlinear functions of the system are used as a nonlinear feedback term. The feedback controller is designed on the basis of stability theory, and the area of feedback gain is determined. The artificial simulation results show that this control method is commendably effective and feasible.
Velocity Feedback Control of a Mechatronics System
Ayman A. Aly
2013-07-01
Full Text Available Increasing demands in performance and quality make drive systems fundamental parts in the progressive automation of industrial process. The analysis and design of Mechatronics systems are often based on linear or linearized models which may not accurately represent the servo system characteristics when the system is subject to inputs of large amplitude. The impact of the nonlinearities of the dynamic system and its stability needs to be clarified.The objective of this paper is to present a nonlinear mathematical model which allows studying and analysis of the dynamic characteristic of an electro hydraulic position control servo. The angular displacement response of motor shaft due to large amplitude step input is obtained by applying velocity feedback control strategy. The simulation results are found to be in agreement with the experimental data that were generated under similar conditions.
Simulation of the ALS longitudinal multibunch feedback system
Longitudinal coupled bunch growth rates in the Advanced Light Source (ALS), a 1.5 GeV electron storage ring for producing synchrotron radiation, indicate the need for damping via a feedback (FB) system. The design of the system is based on the proposed PEP-II longitudinal FB system which uses a digital filter to provide the required phase and amplitude response. We report the results of a detailed computer simulation of the FB system including single particle longitudinal beam dynamics, measured RF cavity fundamental and higher order modes, and response of major FB components such as the power amplifier and kicker. The simulation addresses issues such as required FB power and gain, noise, digital filter effects, and varying initial bunch conditions
System analysis of force feedback microscopy
Rodrigues, Mario S. [CFMC/Dep. de Física, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); Costa, Luca [European Synchrotron Radiation Facility, 6 rue Jules Horowitz BP 220, 38043 Grenoble Cedex (France); Université Joseph Fourier BP 53, 38041 Grenoble Cedex 9 (France); Chevrier, Joël [European Synchrotron Radiation Facility, 6 rue Jules Horowitz BP 220, 38043 Grenoble Cedex (France); Université Grenoble Alpes, Inst NEEL, F-38042 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France); Comin, Fabio [European Synchrotron Radiation Facility, 6 rue Jules Horowitz BP 220, 38043 Grenoble Cedex (France)
2014-02-07
It was shown recently that the Force Feedback Microscope (FFM) can avoid the jump-to-contact in Atomic force Microscopy even when the cantilevers used are very soft, thus increasing force resolution. In this letter, we explore theoretical aspects of the associated real time control of the tip position. We take into account lever parameters such as the lever characteristics in its environment, spring constant, mass, dissipation coefficient, and the operating conditions such as controller gains and interaction force. We show how the controller parameters are determined so that the FFM functions at its best and estimate the bandwidth of the system under these conditions.
System analysis of force feedback microscopy
Rodrigues, Mario S.; Costa, Luca; Chevrier, Joël; Comin, Fabio
2014-02-01
It was shown recently that the Force Feedback Microscope (FFM) can avoid the jump-to-contact in Atomic force Microscopy even when the cantilevers used are very soft, thus increasing force resolution. In this letter, we explore theoretical aspects of the associated real time control of the tip position. We take into account lever parameters such as the lever characteristics in its environment, spring constant, mass, dissipation coefficient, and the operating conditions such as controller gains and interaction force. We show how the controller parameters are determined so that the FFM functions at its best and estimate the bandwidth of the system under these conditions.
Computing using delayed feedback systems: towards photonics
Appeltant, L.; Soriano, M. C.; Van der Sande, G.; Danckaert, J.; Massar, S.; Dambre, J.; Schrauwen, B.; Mirasso, C. R.; Fischer, I.
2012-06-01
Reservoir computing has recently been introduced as a new paradigm in the eld of machine learning. It is based on the dynamical properties of a network of randomly connected nodes or neurons and shows to be very promising to solve complex classication problems in a computationally ecient way. The key idea is that an input generates nonlinearly transient behavior rendering transient reservoir states suitable for linear classication. Our goal is to study up to which extent systems with delay, and especially photonic systems, can be used as reservoirs. Recently an new architecture has been proposed1 , based on a single nonlinear node with delayed feedback. An electronic1 and an opto-electronic implementation2, 3 have been demonstrated and both have proven to be very successful in terms of performance. This simple conguration, which replaces an entire network of randomly connected nonlinear nodes with one single hardware node and a delay line, is signicantly easier to implement experimentally. It is no longer necessary to construct an entire network of hundreds or even thousands of circuits, each one representing a node. With this approach one node and a delay line suce to construct a computational unit. In this manuscript, we present a further investigation of the properties of delayed feedback congurations used as a reservoir. Instead of quantifying the performance as an error obtained for a certain benchmark, we now investigate a task-independent property, the linear memory of the system.
闫庆旭; 侯瑞鸿; 冯德兴; 齐剑冷
2005-01-01
In this article, we study the locally distributed feedback stabilization problem of a nonuniform Euler-Bernoulli beam. Firstly, using the semi-group theory, we establish the wellposedness of the associated closed loop system. Then by proving the uniqueness of the solution to a related ordinary differential equation, we derive the asymptotic stability of the closed loop system. Finally, by means of the piecewise multiplier method, we prove that, by either one distributed force feedback or a distributed moment feedback control, the closed loop system can be exponentially stabilized.
Design considerations for a feedback system to control self-bunching in ion-storage rings
We discuss the feasibility of a feedback system to cure self-bunching of the electron-cooled coasting ion-beam in CELSIUS. Such a system may also aid stable operation of accumulator rings for future spallation neutron sources or heavy ion rings used for inertial fusion energy production
Simulation of a Feedback System for the Attenuation of e-Cloud Driven Instability
Vay, J.-L.; Furman, M.A.; Fox, J.; Rivetta, C.; de Maria, R.; Rumolo, G.
2009-05-04
Electron clouds impose limitations on current accelerators that may be more severe for future machines, unless adequate measures of mitigation are taken. Recently, it has been proposed to use feedback systems operating at high frequency (in the GHz range) to damp single-bunch transverse coherent oscillations that may otherwise be amplified during the interaction of the beam with ambient electron clouds. We have used the simulation package WARP-POSINST and the code Headtail to study the growth rate and frequency patterns in space-time of the electron cloud driven beam breakup instability in the CERN SPS accelerator with, or without, an idealized feedback model for damping the instability.
Simulation of a Feedback System for the Attenuation of e-Cloud Driven Instability
Electron clouds impose limitations on current accelerators that may be more severe for future machines, unless adequate measures of mitigation are taken. Recently, it has been proposed to use feedback systems operating at high frequency (in the GHz range) to damp single-bunch transverse coherent oscillations that may otherwise be amplified during the interaction of the beam with ambient electron clouds. We have used the simulation package WARP-POSINST and the code Headtail to study the growth rate and frequency patterns in space-time of the electron cloud driven beam breakup instability in the CERN SPS accelerator with, or without, an idealized feedback model for damping the instability.
Development of an optical feedback based high accuracy beam transmissometer
Bartz, Robert
1987-11-01
The Phase I research has addressed the need for spectral light transmission data. Over the years the oceanographic community has repeatedly asked for a transmissometer operating at other wavelengths, specifically blue and green. The existing Sea Tech transmissometer is only available with a red LED, (light emitting diode) light source, mainly because LED's at shorter wavelengths have much lower power output. The primary objective of Phase I research was to determine if the transmissometer could be redesigned using LED's of other wavelengths. Constraints imposed on the new design was to achieve the same high performance inherent in the existing red transmissometer that has served the oceanic community so well for over 10 years. During the research performed in Phase I of this project a methodology and technique has been successfully developed for the stabilization of low power LED light sources to be used in the transmissometer. During the Phase I research, both red and blue LED's were evaluated in a optical bridge configuration allowing stabilization of the LED's using optical feedback. The LED's were installed in a collimator having a spatial filter 0.25 mm in diameter and a lens with a focal length of 60 mm resulting in a collimation angle of 4.16 milliradians in air. This same high degree of collimation is used in the existing Sea Tech red transmissometer.
Digital bunch-by-bunch feedback systems allow to detect and counteract longitudinal as well as transverse multi-bunch instabilities. Beam current-dependent grow-damp measurements have been performed in order to characterize these instabilities at the DELTA storage ring. The longitudinal feedback system is used permanently during the operation of the new short-pulse facility in order to damp longitudinal bunch oscillations. Besides that, all three feedback systems are in use as excellent diagnostics tools, e.g. to investigate the injection process or to take data during sudden beam loss for post-processing.
Automatic beam steering in the NSLS storage rings using closed orbit feedback
This paper describes recent work on beam stabilization systems for the NSLS electron storage rings. It also reviews several types of detectors presently available for monitoring beam motion and describes possible schemes for stabilizing photon beams in a storage ring. Finally, it briefly discusses plans for simultaneous stabilization of many beam lines in the storage rings. (orig.)
This paper describes recent work on beam stabilization systems for the NSLS electron storage rings. It also reviews several types of detectors presently available for monitoring beam motion and describes possible schemes for stablizing photon beams in a storage ring. Finally, it briefly discusses plans for simultaneous stabilization of many beam lines in the storage rings
Status of the bunch-by-bunch fast-feedback system at ANKA
Marsching, Sebastian; Hiller, Nicole; Huttel, Erhard; Judin, Vitali; Kehrer, Benjamin; Klein, Marit; Meuter, Christina; Mueller, Anke-Susanne; Nasse, Michael; Schuh, Marcel; Smale, Nigel; Streichert, Max [Karlsruhe Institute of Technology (Germany)
2012-07-01
At ANKA, the synchrotron light source of the Karlsruhe Institute of Technology, a vertical bunch-by-bunch fast-feedback system is being commissioned for damping multi-bunch instabilities and performing beam-dynamics studies. The ANKA synchrotron operates at a regular beam energy of 2.5 GeV while the ANKA injector operates at only 0.5 GeV. Thus, the beam injected into the synchrotron has to be ramped up in energy. Therefore, the fast-feedback system has to be able to damp instabilities over the whole energy range from 0.5 to 2.5 GeV. In this talk, we summarize the progress of the commissioning process and present studies we performed on compensating effects caused by the change of beam energy.
A Classification of Adaptive Feedback in Educational Systems for Programming
Nguyen-Thinh Le
2016-01-01
Over the last three decades, many educational systems for programming have been developed to support learning/teaching programming. In this paper, feedback types that are supported by existing educational systems for programming are classified. In order to be able to provide feedback, educational systems for programming deployed various approaches to analyzing students’ programs. This paper identifies analysis approaches for programs and introduces a classification for adaptive feedback suppo...
Beam alignment system for laser welding system
The patent describes a beam alignment system for laser welding work pieces, such as fuel rod grids for nuclear fuel assemblies. The apparatus for performing various laser-machining comprises a beam alignment system including alignment target means, as well as means for emitting, directing and focusing the laser beam. (U.K.)
Transient Beam Loading in the ALS Harmonic RF System
We report on the commissioning of a higher harmonic radiofrequency system at the Advanced Light Source, designed to improve the beam lifetime. We have achieved an increase above a factor of two in our best results up to now. Transient beam loading of the harmonic cavities, due to the unequal fill patterns, creates the greatest limitations on lifetime improvement. We also describe several interesting effects on the operation of the longitudinal and transverse multibunch feedback systems
The output feedback control for uncertain nonholonomic systems
Qiangde WANG; Chunling WEI; Siying ZHANG
2006-01-01
This paper considers the problems of almost asymptotic stabilization and global asymptotic regulation (GAR) by output feedback for a class of uncertain nonholonomic systems. By combining the nonsmooth change of coordinates and output feedback domination design together, we construct a simple linear time-varying output feedback controller, which can universally stabilize a whole family of uncertain nonholonomic systems. The simulation demonstrates the effectiveness of the proposed controller.
THE FONT5 PROTOTYPE ILC INTRA-TRAIN FEEDBACK SYSTEM AT ATF2
Apsimon, R J; Burrows, P N; Christian, G B; Constance, B; Perry, C; Resta-Lopez, J
2011-01-01
We present the design and beam test results of a prototype beam-based digital feedback system for the Interaction Point of the International Linear Collider. A custom analogue front-end signal processor, FPGA-based digital signal processing boards, and kicker drive amplifier have been designed, built, deployed and tested with beam in the extraction line of the KEK Accelerator Test Facility (ATF2). The system was used to provide orbit correction to the train of bunches extracted from the ATF damping ring. The latency was measured to be approximately 140 ns.
Design And Analysis Of An FPGA-Based Active Feedback Damping System
The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory is a high-intensity proton-based accelerator that produces neutron beams for neutronscattering research. As the most powerful pulsed neutron source in the world, the SNS accelerator has experienced an unprecedented beam instability that has a wide bandwidth (0 to 300MHz) and fast growth time (10 to100 s). In this paper, we propose and analyze several FPGA-based designs for an active feedback damping system. This signal processing system is the first FPGA-based design for active feedback damping of wideband instabilities in high intensity accelerators. It can effectively mitigate instabilities in highintensity protons beams, reduce radiation, and boost the accelerator s luminosity performance. Unlike existing systems, which are designed using analog components, our FPGA-based active feedback damping system offers programmability while maintaining high performance. To meet the system throughput and latency requirements, our proposed designs are guided by detailed analysis of resource and performance tradeoffs. These designs are mapped onto a reconfigurable platform that includes Xilinx Virtex-II Pro FPGAs and high-speed analog-to-digital and digital-toanalog converters. Our results show that our FPGA-based active feedback damping system can provide increased flexibility and improved signal processing performance that are not feasible with existing analog systems.
The CMS Beam Halo Monitor Detector System
CMS Collaboration
2015-01-01
A new Beam Halo Monitor (BHM) detector system has been installed in the CMS cavern to measure the machine-induced background (MIB) from the LHC. This background originates from interactions of the LHC beam halo with the final set of collimators before the CMS experiment and from beam gas interactions. The BHM detector uses the directional nature of Cherenkov radiation and event timing to select particles coming from the direction of the beam and to suppress those originating from the interaction point. It consists of 40 quartz rods, placed on each side of the CMS detector, coupled to UV sensitive PMTs. For each bunch crossing the PMT signal is digitized by a charge integrating ASIC and the arrival time of the signal is recorded. The data are processed in real time to yield a precise measurement of per-bunch-crossing background rate. This measurement is made available to CMS and the LHC, to provide real-time feedback on the beam quality and to improve the efficiency of data taking. In this talk we will describ...
The CMS Beam Halo Monitor Detector System
Stifter, Kelly Marie
2015-01-01
A new Beam Halo Monitor (BHM) detector system has been installed in the CMS cavern to measure the machine-induced background (MIB) from the LHC. This background originates from interactions of the LHC beam halo with the final set of collimators before the CMS experiment and from beam gas interactions. The BHM detector uses the directional nature of Cherenkov radiation and event timing to select particles coming from the direction of the beam and to supress those originating from the interaction point. It consists of 40 quartz rods, placed on each side of the CMS detector, coupled to UV sensitive PMTs. For each bunch crossing the PMT signal is digitized by a charge integrating ASIC and the arrival time of the signal is recorded. The data are processed in real time to yield a precise measurement of per-bunch-crossing background rate. This measurement is made available to CMS and the LHC, to provide real-time feedback on the beam quality and to improve the efficiency of data taking. In this talk we will descri...
The CMS Beam Halo Monitor Detector System
Stifter, Kelly
2015-01-01
A new Beam Halo Monitor (BHM) detector system has been installed in the CMS cavern to measure the machine-induced background (MIB) from the LHC. This background originates from interactions of the LHC beam halo with the final set of collimators before the CMS experiment and from beam gas interactions. The BHM detector uses the directional nature of Cherenkov radiation and event timing to select particles coming from the direction of the beam and to suppress those originating from the interaction point. It consists of 40 quartz rods, placed on each side of the CMS detector, coupled to UV sensitive PMTs. For each bunch crossing the PMT signal is digitized by a charge integrating ASIC and the arrival time of the signal is recorded. The data are processed in real time to yield a precise measurement of per-bunch-crossing background rate. This measurement is made available to CMS and the LHC, to provide real-time feedback on the beam quality and to improve the efficiency of data taking. Here, I present the detector...
Is the ebay feedback system really efficient ? an experimental study
David Masclet; Thierry Pénard
2008-01-01
The eBay Feedback Forum is claimed to be a crucial component of the success of eBay. Many empirical studies have found that this feedback system exerts a deterrent effect on the opportunistic behavior the Internet's anonymity may incite buyers and sellers to adopt. The feedback system in place on eBay is however far from being perfect and may be especially vulnerable to strategic ratings (or nonratings) that might reduce the informational content of feedback profiles. This article aims to exa...
Feedback control design for discrete-time piecewise affine systems
XU Jun; XIE Li-hua
2007-01-01
This paper investigates the design of state feedback and dynamic output feedback stabilizing controllers for discrete-time piecewise affine (PWA) systems. The main objective is to derive design methods that will incorporate the partition information of the PWA systems so as to reduce the design conservatism embedded in existing design methods. We first introduce a transformation that converts the feedback control design problem into a bilinear matrix inequality (BMI) problem. Then, two iterative algorithms are proposed to compute the feedback controllers characterized by the BMI. Several simulation examples are given to demonstrate the advantages of the proposed design.
Design of output feedback controller for a unified chaotic system
Li Wen-Lin; Chen Xiu-Qin; Shen Zhi-Ping
2008-01-01
In this paper,the synchronization of a unified chaotic system is investigated by the use of output feedback controllers;a two-input single-output feedback controller and single-input single-output feedback controller are presented to synchronize the unified chaotic system when the states are not all measurable.Compared with the existing results,the controllers designed in this paper have some advantages such as small feedback gain,simple structure and less conservation.Finally,numerical simulations results are provided to demonstrate the validity and effectiveness of the proposed method.
An FPGA-based Bunch-by-Bunch Position and Angle Feedback System at ATF2
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 ...
Dynamic axial stabilization of counterpropagating beam-traps with feedback control
Tauro, Sandeep; Bañas, Andrew Rafael; Palima, Darwin;
2010-01-01
Optical trapping in a counter-propagating (CP) beam-geometry provides unique advantages in terms of working distance, aberration requirements and intensity hotspots. However, its axial performance is governed by the wave propagation of the opposing beams, which can limit the practical geometries...... real-time rapid repositioning coupled with a strongly enhanced axial trapping for a plurality of particles of varying sizes. We also demonstrate the technique’s adaptability for real-time reconfigurable feedback-trapping of a dynamically growing structure that mimics a continuously dividing cell colony...
Proposed Reactor Operating Experience Feedback System Development
Most events occurring in nuclear power plants are not individually significant, and prevented from progressing to accident conditions by a series of barriers against core damage and radioactive releases. Significant events, if occur, are almost always a breach of these multiple barriers. As illustrated in the 'Swiss cheese' model, the individual layers of defense or 'cheese slices' have weakness or 'holes.' These weaknesses are inconstant, i.e., the holes are open or close at random. When by chance all the holes are aligned, a hazard causes the significant event of concern. Elements of low significant events, inattention to detail, time or economic pressure, uncorrected poor practices/habits, marginal maintenance and equipment care, etc., make holes in the layers of defense; some elements may make more holes in different layers, incurring more chances to be aligned. An effective reduction of the holes, therefore, is gained through better knowledge or awareness of increasing trends of the event elements, followed by appropriate actions. According to the Swiss cheese metaphor, attention to the Operating Experience (OE) feedback system, as opposed to the individual and to randomness, is drawn from a viewpoint of reactor safety
Quantitative Feedback Control of Multiple Input Single Output Systems
Javier Rico-Azagra; Montserrat Gil-Martínez; Jorge Elso
2014-01-01
This paper presents a robust feedback control solution for systems with multiple manipulated inputs and a single measurable output. A structure of parallel controllers achieves robust stability and robust disturbance rejection. Each controller uses the least possible amount of feedback at each frequency. The controller design is carried out in the Quantitative Feedback Theory framework. The method pursues a smart load sharing along the frequency spectrum, where each branch must either coll...
Designing new feedback mangement system Långvik
Dang, Hien
2014-01-01
This thesis is a design project on the field of feedback management, conducted for Långvik hotel. The purpose of this thesis is to recommend a new feedback management system for the hotel that can effectively recognize original reasons for customers’ returning decision. The new approach to feedback management is expected to generate a higher number of re- turned customers subsequent to the summer business peak. The literature review focuses on the connection between customer experience and...
Combined feedforward and feedback control of end milling system
F. Cus; U. Zuperl; J. Balic
2011-01-01
Purpose: Purpose of this paper. An intelligent control system is presented that uses a combination of feedforward and feedback for cutting force control in end milling.Design/methodology/approach: The network is trained by the feedback output that is minimized during training and most control action for disturbance rejection is finally performed by the rapid feedforward action of the network.Findings: The feedback controller corrects for errors caused by external disturbances. The feedforward...
Optical encoder feedback system for levitating rotor system
Khanna, Shrey; Ho, Joe N.; Irwen, Jonathan; Rakka, Gurjinder; Wang, Weichih
2010-03-01
This paper describes the design and fabrication of feedback control system for a three phase motor with a diamagnetically levitating rotor. The planar rotor described in this paper uses a triangular configuration of magnets that rotates due to nine electric coils evenly spaced around the rotor. An optical mechanical feedback system controls the frequency at which the rotor spins. The current input to the coil is controlled by a mechanical relay circuit which latches based on a DC pulse signal generated by a PID control algorithm. The mechanical relay circuit allows current to flow to each coils (the actuators of this system), which then produces a magnetic field strong enough to spin the rotor.
Information feedback strategy for beltways in intelligent transportation systems
Li, Wen-Ting; Li, Jian-Qing; Chen, Bo-Kui; Huang, Xin; Wang, Zhen
2016-03-01
As an important part of the Intelligent Transportation System (ITS), the information feedback strategy has drawn more and more scholars' attention. A variety of feedback strategies are proposed to improve the traffic efficiency. These strategies are based on simple route scenarios, but most route scenarios are always complex in reality. In this letter, based on a complex beltway scenario, we propose a new traffic information feedback strategy called Beltway Feedback Strategy (BFS). The simulation results show that the BFS can effectively improve the transportation ability of beltways.
Geometric Structures of Stable Time-Variant State Feedback Systems
ZHONG Feng-wei; SUN Hua-fei; ZHANG Zhen-ning
2007-01-01
A new technique for considering the stabilizing time-variant state feedback gains is proposed from the viewpoint of information geometry. First, parametrization of the set of all stabilizing time-variant state feedback gains is given. Moreover, a diffeomorphic structure between the set of stabilizing time-variant state feedback gains and the Cartesian product of positive definite matrix and skew symmetric matrix satisfying certain algebraic conditions is constructed. Furth ermore, an immersion and some results about the eigenvalue locations of stable state feedback systems are derived.
A waveguide overloaded cavity kicker for the HLS II longitudinal feedback system
Li, Wubin; Sun, Baogen; Wu, Fangfang; Xu, Wei; Lu, Ping; Yang, Yongliang
2013-01-01
In the upgrade project of Hefei Light Source (HLS II), a new digital longitudinal bunch-by-bunch feedback system will be developed to suppress the coupled bunch instabilities in the storage ring effectively. We design a new waveguide overloaded cavity longitudinal feedback kicker as the feedback actuator. The beam pipe of the kicker is racetrack shape so as to avoid a transition part to the octagonal vacuum chamber. The central frequency and the bandwidth of the kicker have been simulated and optimized to achieve design goals by the HFSS code. The higher shunt impedance can be obtained by using a nose cone to reduce the feedback power requirement. Before the kicker cavity was installed in the storage ring, a variety of measurements were carried out to check its performance. All these results of simulation and measurement are presented.
Design of active feedback controller used in the infrared beam line of SSRF
Background: The infrared beam line consists of many kinds of optical components that are susceptible to the external mechanical vibration, which will be further amplified by the long optical paths to seriously destroy the stability of infrared beam position. Purpose: The active feedback controller is used to stabilize the infrared beam position disturbed by the external environment. Methods: The design of the active feedback controller used in the infrared beam line of SSRF was proposed in this paper firstly, which included its background, light-path layout and operating process. Subsequently, the selections of the crucial components such as detector and actuator were discussed in details. Finally, the correction compensator design and its experimental test were also presented. The correction compensator design was realized by utilizing the frequency response method, and tested in time domain, frequency domain and mathematical model simulation of the controlled object. Results: The experimental tests included time domain step response signal of the controller, the time domain signal and its relevant magnitude spectrum in frequency domain due to the light source simulation vibration. Conclusion: The results show that the maximum effective operating band is 250 Hz and the maximum steady error is 5 μm. (authors)
Digital closed orbit feedback system for the advanced photon source storage ring
The Advanced Photon Source (APS) is a dedicated third-generation synchrotron light source with a nominal energy of 7 GeV and a circumference of 1104 m. The closed orbit feedback system for the APS storage ring employs unified global and local feedback systems for stabilization of particle and photon beams based on digital signal processing (DSP). Hardware and software aspects of the system will be described in this paper. In particular, we will discuss global and local orbit feedback algorithms, PID (proportional, integral, and derivative) control algorithm, application of digital signal processing to compensate for vacuum chamber eddy current effects, resolution of the interaction between global and local systems through decoupling, self-correction of the local bump closure error, user interface through the APS control system, and system performance in the frequency and time domains. The system hardware including the DSPs is distributed in 20 VME crates around the ring, and the entire feedback system runs synchronously at 4-kHz sampling frequency in order to achieve a correction bandwidth exceeding 100 Hz. The required data sharing between the global and local feedback systems is facilitated via the use of fiber-optically-networked reflective memories
Digital closed orbit feedback system for the advanced photon source storage ring
Chung, Y.; Barr, D.; Decker, G. [and others
1995-12-31
The Advanced Photon Source (APS) is a dedicated third-generation synchrotron light source with a nominal energy of 7 GeV and a circumference of 1104 m. The closed orbit feedback system for the APS storage ring employs unified global and local feedback systems for stabilization of particle and photon beams based on digital signal processing (DSP). Hardware and software aspects of the system will be described in this paper. In particular, we will discuss global and local orbit feedback algorithms, PID (proportional, integral, and derivative) control algorithm, application of digital signal processing to compensate for vacuum chamber eddy current effects, resolution of the interaction between global and local systems through decoupling, self-correction of the local bump closure error, user interface through the APS control system, and system performance in the frequency and time domains. The system hardware including the DSPs is distributed in 20 VME crates around the ring, and the entire feedback system runs synchronously at 4-kHz sampling frequency in order to achieve a correction bandwidth exceeding 100 Hz. The required data sharing between the global and local feedback systems is facilitated via the use of fiber-optically-networked reflective memories.
Nonlinear feedback synchronization of hyperchaos in higher dimensional systems
FangJin－Qing; AliMK
1997-01-01
Nonlinear feedback functional method is presented to realize synchronization of hyperchaos in higher dimensional systems,New nonlinear feedback functions and superpositions of linear and nonlinear feedback functions are also introduced to synchronize hyperchaos.The robustness of the method based on the flexibility of choices of feedback functions is discussed.By coupling well-known chaotic or chaotic-hyperchaotic systems in low-dimensional systems,such as Lorenz system,Van der Pol oscillator,Duffing oscillator and Roessler system,ten dimensional hyperchaotic systems are formed as the model systems.It can be found that there is not any noticeable difference in synchronization based on the numbers of positive Lyapunov exponents and of dimensions.
A closed loop feedback system for synchrotron radiation double crystal monochromators
We report on a dc closed loop feedback system for a fixed exit double crystal monochromator. The feedback control is part of a complete system which includes beam position and current monitors. The monochromator consists of two identical crystals mechanically coupled so that the two diffraction planes are almost parallel to each other. The feedback system controls a piezoelectric transducer to maintain the new parallelism, and it can be set under computer control to be at any point in the rocking curve at all times. The system has been thoroughly tested and found to be adequate for EXAFS measurements performed on beamline X18B at the National Synchrotron Light Source at Brookhaven National Laboratory. (orig.)
Beam Cleaning and Collimation Systems
Redaelli, S
2016-01-01
Collimation systems in particle accelerators are designed to dispose of unavoidable losses safely and efficiently during beam operation. Different roles are required for different types of accelerator. The present state of the art in beam collimation is exemplified in high-intensity, high-energy superconducting hadron colliders, like the CERN Large Hadron Collider (LHC), where stored beam energies reach levels up to several orders of magnitude higher than the tiny energies required to quench cold magnets. Collimation systems are essential systems for the daily operation of these modern machines. In this document, the design of a multistage collimation system is reviewed, taking the LHC as an example case study. In this case, unprecedented cleaning performance has been achieved, together with a system complexity comparable to no other accelerator. Aspects related to collimator design and operational challenges of large collimation systems are also addressed.
Corresponding Angle Feedback in an innovative weighted transportation system
Dong, Chuanfei; Ma, Xu
2010-05-01
The optimal information feedback has a significant effect on many socioeconomic systems like stock market and traffic systems aiming to make full use of resources. In this Letter, we study dynamics of traffic flow with real-time information. The influence of a feedback strategy named Corresponding Angle Feedback Strategy (CAFS) is introduced, based on a two-route scenario in which dynamic information can be generated and displayed on the board to guide road users to make a choice. Our model incorporates the effects of adaptability into the cellular automaton models of traffic flow and simulation results adopting this optimal information feedback strategy have demonstrated high efficiency in controlling spatial distribution of traffic patterns compared with the other three information feedback strategies, i.e., vehicle number and flux.
Bowhill, S. A.; Merewether, K. O.
1986-01-01
A simple technique for steering the beam of a multimodule phased array MST (mesosphere, stratosphere, troposphere) radar antenna is described. It is desirable to be able to point the antenna in multiple directions, so as to derive all components of the horizontal velocity. This was done on an experimental basis by adding parallel wire line to the feed and achieving a southward tilt of the antenna. It is proved possible to steer the beam through most of the available range without adversely affecting the VSWR seen from the transmitter. Calibrating the antenna direction can be accomplished by observing radio sources, though there are an inadequate number to cover all directions. For various assumed values of the aspect sensitivity in dB/deg, and the calculated antenna pattern, it is possible to calculate the effective pointing angle of the antenna, defined as that angle which would give an identical location for the centroid of the power spectrum if aspect sensitivity were absent. Using averaged apparent steering directions, eastward and northward winds were calculated for special radar runs simultaneous with 14 balloon launches at Peoria and results are presented.
Truncated predictor feedback for time-delay systems
Zhou, Bin
2014-01-01
This book provides a systematic approach to the design of predictor based controllers for (time-varying) linear systems with either (time-varying) input or state delays. Differently from those traditional predictor based controllers, which are infinite-dimensional static feedback laws and may cause difficulties in their practical implementation, this book develops a truncated predictor feedback (TPF) which involves only finite dimensional static state feedback. Features and topics: A novel approach referred to as truncated predictor feedback for the stabilization of (time-varying) time-delay systems in both the continuous-time setting and the discrete-time setting is built systematically Semi-global and global stabilization problems of linear time-delay systems subject to either magnitude saturation or energy constraints are solved in a systematic manner Both stabilization of a single system and consensus of a group of systems (multi-agent systems) are treated in a unified manner by applying the truncated pre...
Digital closed orbit feedback system for the Advanced Photon Source storage ring
Closed orbit feedback for the Advanced Photon Source (APS) storage ring employs unified global an local feedback systems for stabilization of particle and photon beams based on digital signal processing (DSP). Hardware and software aspects of the system will be described. In particular, we will discuss global and local orbit feedback algorithms, PID (proportional, integral, and derivative) control algorithm. application of digital signal processing to compensate for vacuum chamber eddy current effects, resolution of the interaction between global and local systems through decoupling, self-correction of the local bump closure error, user interface through the APS control system, and system performance in the frequency and time domains. The system hardware, including the DSPS, is distributed in 20 VNE crates around the ring, and the entire feedback system runs synchronously at 4-kHz sampling frequency in order to achieve a correction bandwidth exceeding 100 Hz. The required data sharing between the global and local feedback systems is facilitated via the use of fiber-optically-networked reflective memories
Digital closed orbit feedback system for the Advanced Photon Source storage ring
Chung, Y.; Barr, D.; Decker, G.; Galayda, J.; Lenkszus, F.; Lumpkin, A.; Votaw, A.J. [Accelerator Systems Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States)
1996-09-01
Closed orbit feedback for the Advanced Photon Source (APS) storage ring employs unified global and local feedback systems for stabilization of particle and photon beams based on digital signal processing. Hardware and software aspects of the system will be described. In particular, we will discuss global and local orbit feedback algorithms, PID (proportional, integral, and derivative) control algorithm, application of digital signal processing to compensate for vacuum chamber eddy current effects, resolution of the interaction between global and local systems through decoupling, self-correction of the local bump closure error, user interface through the APS control system, and system performance in the frequency and time domains. The system hardware, including the digital signal processor (DSPs), is distributed in 20 VME crates around the ring, and the entire feedback system runs synchronously at 4-kHz sampling frequency in order to achieve a correction bandwidth exceeding 100 Hz. The required data sharing between the global and local feedback systems is facilitated via the use of fiber-optically networked reflective memories. {copyright} {ital 1996 American Institute of Physics.}
Digital closed orbit feedback system for the Advanced Photon Source storage ring
Chung, Y.; Barr, D.; Decker, G.; Galayda, J.; Lenkszus, F.; Lumpkin, A.; Votaw, A. J.
1996-09-01
Closed orbit feedback for the Advanced Photon Source (APS) storage ring employs unified global and local feedback systems for stabilization of particle and photon beams based on digital signal processing. Hardware and software aspects of the system will be described. In particular, we will discuss global and local orbit feedback algorithms, PID (proportional, integral, and derivative) control algorithm, application of digital signal processing to compensate for vacuum chamber eddy current effects, resolution of the interaction between global and local systems through decoupling, self-correction of the local bump closure error, user interface through the APS control system, and system performance in the frequency and time domains. The system hardware, including the digital signal processor (DSPs), is distributed in 20 VME crates around the ring, and the entire feedback system runs synchronously at 4-kHz sampling frequency in order to achieve a correction bandwidth exceeding 100 Hz. The required data sharing between the global and local feedback systems is facilitated via the use of fiber-optically networked reflective memories.
Fast digital transverse feedback system for bunch train operation in CESR
Rogers, J.T.; Billing, M.G.; Dobbins, J.A. [Cornell Univ., Ithaca, NY (United States). Lab. of Nuclear Studies] [and others
1996-08-01
We have developed a time domain transverse feedback system with the high bandwidth needed to control transverse instabilities when the CESR e{sup +}e{sup -} collider is filled with trains of closely spaced bunches. This system is based on parallel digital processors and a stripline driver. It is capable of acting on arbitrary patterns of bunches having a minimum spacing of 14 ns. Several simplifying features have been introduced. A single shorted stripline kicker driven by one power amplifier is used to control both counter-rotating beams. The desired feedback phase is achieved by sampling the bunch position at a single location on two independently selectable beam revolutions. The system adapts to changes in the betatron tune, bunch pattern, or desired damping rate through the loading of new parameters into the digital processors via the CESR control system. The feedback system also functions as a fast gated bunch current monitor. Both vertical and horizontal loops are now used in CESR operation. The measured betatron damping rates with the transverse feedback system in operation are in agreement with the analytical prediction and a computer simulation developed in connection with this work. (author)
Fast digital transverse feedback system for bunch train operation in CESR
We have developed a time domain transverse feedback system with the high bandwidth needed to control transverse instabilities when the CESR e+e-collider is filled with trains of closely spaced bunches. This system is based on parallel digital processors and a stripline driver. It is capable of acting on arbitrary patterns of bunches having a minimum spacing of 14 ns. Several simplifying features have been introduced. A single shorted stripline kicker driven by one power amplifier is used to control both counter-rotating beams. The desired feedback phase is achieved by sampling the bunch position at a single location on two independently selectable beam revolutions. The system adapts to changes in the betatron tune, bunch pattern, or desired damping rate through the loading of new parameters into the digital processors via the CESR control system. The feedback system also functions as a fast gated bunch current monitor. Both vertical and horizontal loops are now used in CESR operation. The measured betatron damping rates with the transverse feedback system in operation are in agreement with the analytical prediction and a computer simulation developed in connection with this work. (author)
FANG Jin-Qing; LUO Xiao-Shu; HUANG Guo-Xian
2006-01-01
Subject of the halo-chaos control in beam transport networks (channels) has become a key concerned issue for many important applications of high-current proton beam since 1990'. In this paper, the magnetic field adaptive control based on the neuralnetwork with time-delayed feedback is proposed for suppressing beam halo-chaos in the beam transport network with periodic focusing channels. The envelope radius of high-current proton beam is controlled to reach the matched beam radius by suitably selecting the control structure and parameter of the neural network, adjusting the delayed-time and control coefficient of the neural network.
ITER Neutral Beam Injection System
A Japanese design proposal of the ITER Neutral Beam Injection System (NBS) which is consistent with the ITER common design requirements is described. The injection system is required to deliver a neutral deuterium beam of 75MW at 1.3MeV to the reactor plasma and utilized not only for plasma heating but also for current drive and current profile control. The injection system is composed of 9 modules, each of which is designed so as to inject a 1.3MeV, 10MW neutral beam. The most important point in the design is that the injection system is based on the utilization of a cesium-seeded volume negative ion source which can produce an intense negative ion beam with high current density at a low source operating pressure. The design value of the source is based on the experimental values achieved at JAERI. The utilization of the cesium-seeded volume source is essential to the design of an efficient and compact neutral beam injection system which satisfies the ITER common design requirements. The critical components to realize this design are the 1.3MeV, 17A electrostatic accelerator and the high voltage DC acceleration power supply, whose performances must be demonstrated prior to the construction of ITER NBI system. (author)
Maslov, M.A.; Mokhov, N.V.; Yazynin (Superconducting Super Collider Lab., Dallas, TX (United States) Institut Fiziki Vysokikh Ehnergij, Protvino (USSR))
1991-06-01
In this paper we present the results of a full-scale study of a beam scraping system that is designed to guarantee reliable operation of the SSC throughout the whole cycle and for minimum background for experiments at the interaction regions. The machine aperture limits and beam loss formation are analyzed. Simulation programs and a calculational model are described. The physics of beam scraping is explored, and measures to increase significantly the system efficiency are determined. A tolerable scraping rate, taking into account scraper material integrity, quench limits in downstream superconducting magnets, radiation shielding requirements, and minimal beam halo levels at the IPs are also determined. Finally, a complete multi-component scraper system in the SSC East Cluster is proposed. Throughout the paper we define a scraper as a primary absorber consisting of precise movable jaws that have a flat inner edge along the circulation beam and which may be forced to touch the beam halo in horizontal or vertical planes. Secondary absorbers -- collimators -- are destined to intercept outscattered protons and other particles produced in scraper material. All these are surrounded with a radiation shielding. 15 refs., 50 figs., 13 tabs.
Feedback-linearization and feedback-feedforward decentralized control for multimachine power system
De Tuglie, Enrico [Dipartimento di Ingegneria dell' Ambiente, e per lo Sviluppo Sostenibile - DIASS, Politecnico di Bari, Viale del Turismo 8, 74100 Taranto (Italy); Iannone, Silvio Marcello; Torelli, Francesco [Dipartimento di Elettrotecnica, ed Elettronica - DEE, Politecnico di Bari, Via Re David 200, 70125 Bari (Italy)
2008-03-15
In this paper a decentralized nonlinear controller for large-scale power systems is investigated. The proposed controller design is based on the input-output feedback linearization methodology. In order to overcome computational difficulties in adopting such methodology, the overall interconnected nonlinear system, given as n-order, is analyzed as a cascade connection of an n{sub 1}-order nonlinear subsystem and an n{sub 2}-order linear subsystem. The controller design is obtained by applying input-output feedback linearization to the nonlinear subsystem and adopting a tracking control scheme, based on feedback-feedforward technique, for the linear subsystem. In the assumed system model, which is characterised by an interconnected structure between generating units, a decentralised adaptive controller is implemented by decentralizing these constraints. The use of a totally decentralised controller implies a system performance decay with respect to performance when the system is equipped with a centralised controller. Fortunately, the robustness of the proposed controller, based on input-output feedback procedure, guarantees good performance in terms of disturbance even when disturbances are caused by decentralization of interconnection constraints. Test results, provided on the IEEE 30 bus test system, demonstrate the effectiveness and practical applicability of proposed methodology. (author)
Weighted congestion coefficient feedback in intelligent transportation systems
In traffic systems, a reasonable information feedback can improve road capacity. In this Letter, we study dynamics of traffic flow with real-time information. And the influence of a feedback strategy named Weighted Congestion Coefficient Feedback Strategy (WCCFS) is introduced, based on a two-route scenario in which dynamic information can be generated and displayed on the board to guide road users to make a choice. Our model incorporates the effects of adaptability into the cellular automaton models of traffic flow and simulation results adopting this optimal information feedback strategy have demonstrated high efficiency in controlling spatial distribution of traffic patterns compared with the other three information feedback strategies, i.e., vehicle number and flux.
Weighted congestion coefficient feedback in intelligent transportation systems
Dong, Chuan-Fei; Ma, Xu; Wang, Bing-Hong
2010-03-01
In traffic systems, a reasonable information feedback can improve road capacity. In this Letter, we study dynamics of traffic flow with real-time information. And the influence of a feedback strategy named Weighted Congestion Coefficient Feedback Strategy (WCCFS) is introduced, based on a two-route scenario in which dynamic information can be generated and displayed on the board to guide road users to make a choice. Our model incorporates the effects of adaptability into the cellular automaton models of traffic flow and simulation results adopting this optimal information feedback strategy have demonstrated high efficiency in controlling spatial distribution of traffic patterns compared with the other three information feedback strategies, i.e., vehicle number and flux.
Indirect Identification of Linear Stochastic Systems with Known Feedback Dynamics
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.
Large deviation theory to model systems under an external feedback
Gagliardi, Alessio; Pecchia, Alessandro; Di Carlo, Aldo
2016-01-01
In this paper we address the problem of systems under an external feedback. This is performed using a large deviation approach and rate distortion from information theory. In particular we define a lower boundary for the maximum entropy reduction that can be obtained using a feedback apparatus with a well defined accuracy in terms of measurement of the state of the system. The large deviation approach allows also to define a new set of potentials, including information, which similarly to mor...
Interactive query expansion and relevance feedback for document retrieval systems
Efthimiadis, E.N.
1992-01-01
This thesis is aimed at investigating interactive query expansion within the context of a relevance feedback system that uses term weighting and ranking in searching online databases that are available through online vendors. Previous evaluations of relevance feedback systems have been made in laboratory conditions and not in a real operational environment. The research presented in this thesis followed the idea of testing probabilistic retrieval techniques in an operational environment. The ...
Antiproton source beam position system
The TeV I Beam Position Monitor (BPM) system is designed to provide a useful diagnostic tool during the commissioning and operational phases of the antiproton source. Simply stated the design goal is to provide single turn position information for intensities of > 1x109 particles, and multi-turn (clocked orbit) information for beam intensities of > 1x107 particles, both with sub-millimeter resolution. It is anticipated that the system will be used during commissioning for establishing the first turn through the Debuncher and Accumulator, for aligning injection orbits, for providing information necessary to correct closed orbits, and for measuring various machine parameters (e.g. tunes, dispersion, aperture, chromaticity). During normal antiproton operation the system will be used to monitor the beam position throughout the accumulation process
Fast digital feedback control systems for accelerator RF system using FPGA
Feedback control system plays important role for proper injection and acceleration of beam in particle accelerators by providing the required amplitude and phase stability of RF fields in accelerating structures. Advancement in the field of digital technology enables us to develop fast digital feedback control system for RF applications. Digital Low Level RF (LLRF) system offers the inherent advantages of Digital System like flexibility, adaptability, good repeatability and reduced long time drift errors compared to analog system. To implement the feedback control algorithm, I/Q control scheme is used. By properly sampling the down converted IF signal using fast ADC we get accurate feedback signal and also eliminates the need of two separate detectors for amplitude and phase detection. Controller is implemented in Vertex-4 FPGA. Codes for control algorithms which controls the amplitude and phase in all four quadrants with good accuracy are written in the VHDL. I/Q modulator works as common actuator for both amplitude and phase correction. Synchronization between RF, LO and ADC clock is indispensable and has been achieved by deriving the clock and LO signal from RF signal itself. Control system has been successfully tested in lab with phase and amplitude stability better then ±1% and ±1° respectively. High frequency RF signal is down converted to IF using the super heterodyne technique. Super heterodyne principal not only brings the RF signal to the Low IF frequency at which it can be easily processed but also enables us to use the same hardware and software for other RF frequencies with some minor modification. (author)
Analysis of DSP-based longitudinal feedback system: Trials at SPEAR and ALS
Recently a single-channel prototype of the proposed PEP-II longitudinal feedback system was successfully demonstrated at SPEAR and ALS on single-bunch beams. The phase oscillations are detected via a wide-band pick up. The feedback signal is then computed using a digital signal processor (DSP) and applied to the beam by phase modulating the rf. We analyze results in the frequency- and the time-domain and show how the closed-loop transfer functions can be obtained rigorously by proper modeling of the various components of this hybrid continuous/digital system. The technique of downsampling was used in the experiments to reduce the number of computations and allowed the use of the same digital hardware on both machines
Secondo, R.; Vay, J. L.; Venturini, M.; Fox, J. D.; Rivetta, C. H.; Hofle, W.
2011-03-28
Transverse Single-Bunch Instabilities due to the Electron Cloud effect are limiting the operation at high current of the SPS at CERN. Recently a high-bandwidth Feedback System has been proposed as a possible solution to stabilize the beam and is currently under study. We analyze the dynamics of the bunch actively damped with a simple model of the Feedback in the macro-particle code WARP, in order to investigate the limitations of the System such as the minimum amount of power required to maintain stability. We discuss the feedback model, report on simulation results and present our plans for further development of the numerical model.
Yang Zhang; Sheng Qiang
2011-01-01
Concrete crane beam on a rock wall on a new structure used in underground building has become more common in recent year. But the concrete beam cracking problem always perplexes scientists and engineers. In order to solve this, the construction information inversion and feedback analysis method is applied. A beam section was taken as a prototype experiment. The temperature and construction data was collected to inverse some necessary thermal parameters. According to the characteristics of con...
Behavioral System Feedback Measurement Failure: Sweeping Quality under the Rug
Mihalic, Maria T.; Ludwig, Timothy D.
2009-01-01
Behavioral Systems rely on valid measurement systems to manage processes and feedback and to deliver contingencies. An examination of measurement system components designed to track customer service quality of furniture delivery drivers revealed the measurement system failed to capture information it was designed to measure. A reason for this…
SIMULATION OF E-CLOUD DRIVEN INSTABILITY AND ITS ATTENUATION USING A FEEDBACK SYSTEM IN THE CERN SPS
Vay, J.-L.; Byrd, J. M.; Furman, M. A.; Secondo, R.; Venturini, M.; Fox, J. D.; Rivetta, C. H.; Hofle, W.
2010-05-03
Electron clouds have been shown to trigger fast growing instabilities on proton beams circulating in the SPS [1], and a feedback system to control the instabilities is under active development [2]. We present the latest improvements to the Warp-Posinst simulation framework and feedback model, and its application to the self-consistent simulations of two consecutive bunches interacting with an electron cloud in the SPS.
Simulation of E-Cloud driven instability and its attenuation using a feedback system in the CERN SPS
Vay, JL; Furman, M; Secondo, R; Venturini, M; Fox, J; Rivetta, C; Hofle, W
2010-01-01
Electron clouds have been shown to trigger fast growing instabilities on proton beams circulating in the SPS [1], and a feedback system to control the instabilities is under active development [2]. We present the latest improvements to the Warp-Posinst simulation framework and feedback model, and its application to the self-consistent simulations of two consecutive bunches interacting with an electron cloud in the SPS.
Simulation of E-Cloud Driven Instability And Its Attenuation Using a Feedback System in the CERN SPS
Vay, Jean-Luc; /LBL, Berkeley; Byrd, John; /LBL, Berkeley; Furman, Miguel; /LBL, Berkeley; Penn, Gregory; /LBL, Berkeley; Secondo, Raffaello; /LBL, Berkeley; Venturini, Marco /LBL, Berkeley; Fox, John; /SLAC; Rivetta, Claudio; /SLAC
2012-07-06
Electron clouds have been shown to trigger fast growing instabilities on proton beams circulating in the SPS, and a feedback system to control the instabilities is under active development. We present the latest improvements to the Warp-Posinst simulation framework and feedback model, and its application to the self-consistent simulations of two consecutive bunches interacting with an electron cloud in the SPS.
Simulation of E-Cloud Driven Instability And Its Attenuation Using a Feedback System in the CERN SPS
Electron clouds have been shown to trigger fast growing instabilities on proton beams circulating in the SPS, and a feedback system to control the instabilities is under active development. We present the latest improvements to the Warp-Posinst simulation framework and feedback model, and its application to the self-consistent simulations of two consecutive bunches interacting with an electron cloud in the SPS.
SIMULATION OF E-CLOUD DRIVEN INSTABILITY AND ITS ATTENUATION USING A FEEDBACK SYSTEM IN THE CERN SPS
Electron clouds have been shown to trigger fast growing instabilities on proton beams circulating in the SPS (1), and a feedback system to control the instabilities is under active development (2). We present the latest improvements to the Warp-Posinst simulation framework and feedback model, and its application to the self-consistent simulations of two consecutive bunches interacting with an electron cloud in the SPS.
Optimal nonlinear feedback control of quasi-Hamiltonian systems
朱位秋; 应祖光
1999-01-01
An innovative strategy for optimal nonlinear feedback control of linear or nonlinear stochastic dynamic systems is proposed based on the stochastic averaging method for quasi-Hamiltonian systems and stochastic dynamic programming principle. Feedback control forces of a system are divided into conservative parts and dissipative parts. The conservative parts are so selected that the energy distribution in the controlled system is as requested as possible. Then the response of the system with known conservative control forces is reduced to a controlled diffusion process by using the stochastic averaging method. The dissipative parts of control forces are obtained from solving the stochastic dynamic programming equation.
Uniform and Model-Driven Engineering of Feedback Control Systems
Křikava, Filip; Collet, Philippe; Blay-Fornarino, Mireille
2011-01-01
Engineering and reusing feedback control systems face challenging issues, such as structuring control loops to allow for fine-grained reasoning about their architecture. We propose a model-driven approach in which all major parts of the feedback control are uniformly designed as first-class adaptive elements. Expected properties of the approach are discussed and illustrated on a real scenario of overload control in a grid middleware.
Output feedback for linear multivariable systems with parameter uncertainty.
Basuthakur, S.; Knapp, C. H.
1973-01-01
A minimax design method is applied to the problem of obtaining an acceptable output feedback matrix for linear multivariable systems with parameter uncertainty. The result is a set of nonlinear matrix equations (similar to those obtained by Levine and Athans (1970)), which must be solved for the feedback matrix. An example illustrates the technique and the fact that better results are achieved for large parameter variation than with a purely nominal design.
Implementing a Measurement Feedback System: A Tale of Two Sites.
Bickman, Leonard; Douglas, Susan R; De Andrade, Ana Regina Vides; Tomlinson, Michele; Gleacher, Alissa; Olin, Serene; Hoagwood, Kimberly
2016-05-01
A randomized experiment was conducted in two outpatient clinics evaluating a measurement feedback system called contextualized feedback systems. The clinicians of 257 Youth 11-18 received feedback on progress in mental health symptoms and functioning either every 6 months or as soon as the youth's, clinician's or caregiver's data were entered into the system. The ITT analysis showed that only one of the two participating clinics (Clinic R) had an enhanced outcome because of feedback, and only for the clinicians' ratings of youth symptom severity on the SFSS. A dose-response effect was found only for Clinic R for both the client and clinician ratings. Implementation analyses showed that Clinic R had better implementation of the feedback intervention. Clinicians' questionnaire completion rate and feedback viewing at Clinic R were 50 % higher than clinicians at Clinic U. The discussion focused on the differences in implementation at each site and how these differences may have contributed to the different outcomes of the experiment. PMID:25876736
ATF neutral beam injection system
The Advanced Toroidal Facility is a stellarator torsatron being built at Oak Ridge National Laboratory to investigate improved plasma confinement schemes. Plasmas heating will be carried out predominantly by means of neutral beam injection. This paper describes the basic parameters of the injection system. Numerical calculations were done to optimize the aiming of the injectors. The results of these calculations and their implications on the neutral power to the machine are elaborated. The effects of improving the beam optics and altering the focal length on the power transmitted to the plasma are discussed
The operation of a longitudinal multi-bunch damping system using digital signal processing techniques is shown via measurements from the LBL Advanced Light Source. The feedback system (developed for use by PEP-II, ALS and DAΦNE) uses a parallel array of signal processors to implement a bunch by bunch feedback system for sampling rates up to 500 MHz. The programmable DSP system allows feedback control as well as accelerator diagnostics. A diagnostic technique is illustrated which uses the DSP system to excite and then damp the beam. The resulting 12 ms time domain transient is Fourier analyzed to provide the simultaneous measurement of growth rates and damping rates of all unstable coupled-bunch beam modes
The operation of a longitudinal multibunch damping system using digital signal processing (DSP) techniques is shown via measurements from the Lawrence Berkeley Laboratory (LBL) Advanced Light Source (ALS). The feedback system (developed for use by PEP-II, ALS, and DAΦNE) uses a parallel array of signal processors to implement a bunch-by-bunch feedback system for sampling rates up to 500 MHz. The programmable DSP system allows feedback control as well as accelerator diagnostics. A diagnostic technique is illustrated which uses the DSP system to excite and then damp the beam. The resulting 12-ms time domain transient is Fourier analyzed to provide the simultaneous measurement of growth rates and damping rates of all unstable coupled-bunch beam modes. copyright 1997 American Institute of Physics
Quantum feedback in a non-resonant cavity QED system
Photon correlation measurements reveal the response of the conditional evolution of the cavity QED system to a novel quantum feedback protocol. A photodetection collapses the state of the system and triggers a feedback pulse with an adjustable delay and amplitude that alters the intensity driving the system. The conditional evolution of the system freezes into a new steady state where it resides until, after an amount of time determined by the experimenter, it re-equilibrates into the original steady state. We carry out a sensitivity analysis using a theoretical model with atomic detuning and make quantitative comparisons with measured results
Asymptotic stabilization of nonlinear systems using state feedback
This paper studies the design of state-feedback controllers for the stabilization of single-input single-output nonlinear systems x = f(x) + g(x)u, y = h(x). Two approaches for the stabilization problem are given; the asymptotic stability is achieved by means of: a) nonlinear state feedback: two nonlinear feedbacks are used; the first separates the system in a controllable linear part and in the zeros-dynamic part. The second feedback generates an asymptotically stable equilibrium on the manifold where this dynamics evolves; b) nonlinear dynamic feedback: conditions are established under which the system can follow the output of a completely controllable bilinear system which uses bounded controls. This fact enables the system to reach, using bounded controls too, a desired output value in finite time. As this value corresponds to a state that lays in the attraction basin of a stable equilibrium with the same output, the system evolves to that point. The two methods are illustrated by examples. (Author)
Mitigation of ground motion effects via feedback systems for the Compact Linear Collider
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 expert knowledge, which is used by an optimisation algorithm to minimise the luminosity loss due to ground motion. This approach speeds up the design process significantly, while at the same time improving the orbit feedback performance compared to standard methods. Beside the L-FB, simple but effective designs for the interaction point feedback and cost reduction options for the quadrupole stabilisation are presented. For the design of all these feedback systems models of the ground motion influence on different beam parameters such as beam offset, beam size and luminosity have been derived by adapting and extending existent models. To design, improve and validate the ground motion mitigation methods, a simulation framework was set up, which includes a ground motion generator, beam tracking, beam-beam interaction and all mitigation methods. The simulations show that the ground motion mitigation methods can efficiently preserve the CLIC luminosity. Due to our
Proton beam therapy control system
Baumann, Michael A.; Beloussov, Alexandre V.; Bakir, Julide; Armon, Deganit; Olsen, Howard B.; Salem, Dana
2008-07-08
A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.
Dynamical behaviour of Liu system with time delayed feedback
Qian Qin; Wang Lin; Ni Qiao
2008-01-01
This paper investigates the dynamical behaviour of the Liu system with time delayed feedback.Two typical situations are considered and the effect of time-delay parameter on the dynamics of the system is discussed.It is shown that the Liu system with time delayed feedback may exhibit interesting and extremely rich dynamical behaviour.The evolution of the dynamics is shown to be complex with varying time-delay parameter.Moreover,the strange attractor like 'wormhole' is detected via numerical simulations.
Performance of the transverse coupled-bunch feedback system in the SRRC
Hsu, K.T.; Kuo, C.C.; Kuo, C.H.; Lin, K.K.; Ueng, T.S.; Weng, W.T.
1996-10-01
A transverse feedback system has been implemented and commissioned in the SRRC storage ring to suppress transverse coupled-bunch oscillations of the electron beam. The system includes transverse oscillation detectors, notch filter, baseband quadrature processing circuitry, power amplifiers, and kickers. To control a large number of transverse coupled-bunch modes, the system is broad-band, bunch-by- bunch in nature. Because the system is capable of bunch-by-bunch correction, it can also be useful for suppressing instabilities introduced by ions. The sextupole strength was then reduced to improve dynamic aperture and hence lifetime of the storage ring.
Plasma flute oscillation stabilization by means of a feedback system
Considered in this paper is the possibility of stabilizing flute oscillations of plasma in right traps with the aid of a feedback system involving measurement of the radial component of a disturbed electric field. It is assumed that the plasma is confined along the Z axis, while transducers and suppressing electrodes may be arranged at different distances from the axis of the system. For the flute oscillation equation in which the finite length of the plasma along the magnetic field is taken into account, an eigenvalue problem is examined with boundary conditions simulating the feedback system. It is assumed that the transfer factor is independent of frequency and that the azimuthal modes are separated. Numerical methods are used to study effects of the longitudinal dimensions of plasma, magnetic field gradient and vacuum region size on stability. Oscillation stability boundaries have been derived, depending on the feedback factor values and the transducer location
Feedback Control Systems Loop Shaping Design with Practical Considerations
Kopsakis, George
2007-01-01
This paper describes loop shaping control design in feedback control systems, primarily from a practical stand point that considers design specifications. Classical feedback control design theory, for linear systems where the plant transfer function is known, has been around for a long time. But it s still a challenge of how to translate the theory into practical and methodical design techniques that simultaneously satisfy a variety of performance requirements such as transient response, stability, and disturbance attenuation while taking into account the capabilities of the plant and its actuation system. This paper briefly addresses some relevant theory, first in layman s terms, so that it becomes easily understood and then it embarks into a practical and systematic design approach incorporating loop shaping design coupled with lead-lag control compensation design. The emphasis is in generating simple but rather powerful design techniques that will allow even designers with a layman s knowledge in controls to develop effective feedback control designs.
Velocity Feedback Control of a Mechatronics System
Ayman A. Aly
2013-01-01
Increasing demands in performance and quality make drive systems fundamental parts in the progressive automation of industrial process. The analysis and design of Mechatronics systems are often based on linear or linearized models which may not accurately represent the servo system characteristics when the system is subject to inputs of large amplitude. The impact of the nonlinearities of the dynamic system and its stability needs to be clarified.The objective of this paper is to present a n...
Experience feedback system of nuclear power plant under construction
The Experience Feedback System of Hainan Nuclear Power Plant under construction, which is a typical EPC nuclear power project, is introduced in the paper. And the good practice of the system set a good example for those NPPs under construction in China. (authors)
Note: Design of a laser feedback interferometer with double diffraction system
Guo, Dongmei, E-mail: guodongmei@njnu.edu.cn; Wang, Ming [Jiangsu Key Laboratory on Opto-Electronic Technology, School of Physical Science and Technology, Nanjing Normal University, Nanjing 210023 (China)
2015-09-15
A novel laser feedback interferometer with double diffraction system is proposed in this paper. A beam emitted from the laser is incident onto a transmission grating. The mth order beam is vertically reflected by a mirror and diffracted again by the grating. The double-diffracted beam returns into the laser cavity and mixes with the light inside the active cavity, thus generating a modulation of both the amplitude and the frequency of the lasing field. Theoretical analysis and experimental observations show that the output signal of the proposed system depends on the grating pitch and the direction of the phase movement can be obtained from inclination of the interference signal. It provides a potential displacement sensor with high stability and quite a compact configuration.
Transfer Function Model of Multirate Feedback Control Systems
无
2001-01-01
Based on the suitably defined multivariable version of Krancoperators and the extended input and output vectors, the multirate sampling plant is transformed to a equivalent time invariant single rate one, then the transfer function model of the multivariable multirate sampling plant is obtained. By combining this plant model with the time invariant description of the multirate controller in terms of extended vectors, the closed-loop transfer function model of the multirate feedback control system can be determinated. This transfer function model has a very simple structure, and can be used as a basis for the analysis and synthesis of the multirate sampling feedback control systems in the frequency domain.
KTeV beam systems design report
Bocean, V.; Childress, S.; Coleman, R. [and others
1997-09-01
The primary and secondary beams for the KTeV experiments E799-II and E832 are discussed. The specifications are presented and justified. The technical details of the implementation of the primary beam transport and stability are detailed. The target, beam dump, and radiation safety issues are discussed. The details of the collimation system for the pair of secondary beams are presented.
KTeV beam systems design report
The primary and secondary beams for the KTeV experiments E799-II and E832 are discussed. The specifications are presented and justified. The technical details of the implementation of the primary beam transport and stability are detailed. The target, beam dump, and radiation safety issues are discussed. The details of the collimation system for the pair of secondary beams are presented
Stabilization of elastic systems by collocated feedback
Ammari, Kaïs
2015-01-01
By introducing a new stabilization methodology, this book characterizes the stability of a certain class of systems. The stability (exponential, polynomial, or weaker) for the closed loop problem is reduced to an observability estimate for the corresponding uncontrolled system combined with a boundedness property of the transfer function of the associated open loop system. A similar strategy is applied to systems where a delay term is added. The book concludes with many concrete examples. This book is addressed to graduate students in mathematics or engineering and also to researchers with an interest in stabilization and control systems governed by partial differential equations.
Fuzzy Feedback Scheduling of Resource-Constrained Embedded Control Systems
Xia, Feng; Tian, Yu-Chu; Tade, Moses; Dong, Jinxiang
2008-01-01
The quality of control (QoC) of a resource-constrained embedded control system may be jeopardized in dynamic environments with variable workload. This gives rise to the increasing demand of co-design of control and scheduling. To deal with uncertainties in resource availability, a fuzzy feedback scheduling (FFS) scheme is proposed in this paper. Within the framework of feedback scheduling, the sampling periods of control loops are dynamically adjusted using the fuzzy control technique. The feedback scheduler provides QoC guarantees in dynamic environments through maintaining the CPU utilization at a desired level. The framework and design methodology of the proposed FFS scheme are described in detail. A simplified mobile robot target tracking system is investigated as a case study to demonstrate the effectiveness of the proposed FFS scheme. The scheme is independent of task execution times, robust to measurement noises, and easy to implement, while incurring only a small overhead.
Hardware design and implementation of the closed-orbit feedback system at APS
The Advanced Photon Source (APS) storage ring will utilize a closed-orbit feedback system in order to produce a more stable beam. The specified orbit measurement resolution is 25 microns for global feedback and 1 micron for local feedback. The system will sample at 4 kHz and provide a correction bandwidth of 100 Hz. At this bandwidth, standard rf BPMs will provide a resolution of 0.7 micron, while specialized miniature BPMs positioned on either side of the insertion devices for local feedback will provide a resolution of 0.2 micron (1). The measured BPM noise floor for standard BPMs is 0.06 micron per root hertz mA. Such a system has been designed, simulated, and tested on a small scale (2). This paper covers the actual hardware design and layout of the entire closed-loop system. This includes commercial hardware components, in addition to many components designed and built in-house. The paper will investigate the large-scale workings of all these devices, as well as an overall view of each piece of hardware used
Decentralized-feedback pole placement of linear systems
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.
High power neutral beam systems
Spurred by the requirement to supply megawatts of power to heat magnetically confined plasmas to temperatures of interest for fusion research, a new class of low energy, high power accelerators termed neutral beam injectors has been developed. Industry has played an important role in building upon technology advances at the national laboratories to engineer neutral beam injectors to meet the needs of specific users. A brief retrospective of the field is presented, with emphasis upon one particular application, that of DIII-D, a large tokamak at General Atomics. In this instance, the role of industry has been especially extensive because the user/system integrator is itself an industrial concern. 4 refs., 7 figs., 2 tabs
Feedback Improvement in Automatic Program Evaluation Systems
Skupas, Bronius
2010-01-01
Automatic program evaluation is a way to assess source program files. These techniques are used in learning management environments, programming exams and contest systems. However, use of automated program evaluation encounters problems: some evaluations are not clear for the students and the system messages do not show reasons for lost points.…
Requirements of CLIC Beam Loss Monitoring System
Sapinski, M; Holzer, EB; Jonker, M; Mallows, S; Otto, T; Welsch, C
2010-01-01
The Compact Linear Collider (CLIC) [1] is a proposed multi-TeV linear electron-positron collider being designed by a world-wide collaboration. It is based on a novel twobeam acceleration scheme in which two beams (drive and main beam) are placed in parallel to each other and energy is transferred from the drive beam to the main one. Beam losses on either of them can have catastrophic consequences for the machine, because of high intensity (drive beam) or high energy and small emittance (main beam). In the framework of machine protection, a Beam Loss Monitoring (BLM) system has to be put in place. This paper discusses the requirements for the beam loss system in terms of detector sensitivity, resolution, dynamic range and ability to distinguish losses originating from various sources. The two-beam module where the protection from beam losses is particularly challenging and important, is studied.
PUMPED LASER SYSTEM USING FEEDBACK TO PUMP MEANS
2008-01-01
A laser system according to the invention comprises pump generating means (xO2, xO3) for generating at least a first and a second, preferably focused, pump beam, and lasing means (xO6, xO7) for emitting radiation by being appropriately pumped. The lasing means (xO6, xO7) is disposed in a first...... resonator so as to receive the first pump beam in order to generate a first beam (x21) having a first frequency, and the lasing means (xO6, xO7) is disposed in a second resonator so as to receive the second pump beam in order to generate a second beam (x22) having a second frequency. At least one Q...... fed back to a regulation system (x14), said regulation system (x14) controlling said pump generating means (xO2, xO3)....
Operating experience feedback report - Air systems problems
This report highlights significant operating events involving observed or potential failures of safety-related systems in U.S. plants that resulted from degraded or malfunctioning non-safety grade air systems. Based upon the evaluation of these events, the Office for Analysis and Evaluation of Operational Data (AEOD) concludes that the issue of air systems problems is an important one which requires additional NRC and industry attention. This report also provides AEOD's recommendations for corrective actions to deal with the issue. (author)
Output feedback regulator design for jet engine control systems
Merrill, W.
1977-01-01
A multivariable control design procedure based on the output feedback regulator formulation is described and applied to an F100 turbofan engine model. Full order model dynamics, are incorporated in the example design. The effect of actuator dynamics on closed loop performance is investigated. Also, the importance of turbine inlet temperature as an element of the dynamic feedback is studied. Step responses are given to indicate the improvement in system performance with this control. Calculation times for all experiments are given in CPU seconds for comparison purposes.
Configuration and Validation of the LHC Beam Loss Monitoring System
Zamantzas, C; Emery, J; Fitzek, J; Follin, F; Jackson, S; Kain, V; Kruk, G; Misiowiec, M; Roderick, C; Sapinski, M
2009-01-01
The LHC Beam Loss Monitoring (BLM) system is one of the most complex instrumentation systems deployed in the LHC. As well as protecting the machine, the system is also used as a means of diagnosing machine faults, and providing feedback of losses to the control room and several systems such as the Collimation, the Beam Dump and the Post-Mortem. The system has to transmit and process signals from over 4’000 monitors, and has approaching 3 million configurable parameters. This paper describes the types of configuration data needed, the means used to store and deploy all the parameters in such a distributed system and how operators are able to alter the operating parameters of the system, particularly with regard to the loss threshold values. The various security mechanisms put in place, both at the hardware and software level, to avoid accidental or malicious modification of these BLM parameters are also shown for each case.
Swing Damping for Helicopter Slung Load Systems using Delayed Feedback
Bisgaard, Morten; la Cour-Harbo, Anders; Bendtsen, Jan Dimon
2009-01-01
This paper presents the design and verification of a swing reducing controller for helicopter slung load systems using intentional delayed feedback. It is intended for augmenting a trajectory tracking helicopter controller and thereby improving the slung load handing capabilities for autonomous h...
Time-optimal feedback control for linear systems
The paper deals with the results of qualitative investigations of the time-optimal feedback control for linear systems with constant coefficients. In the first section, after some definitions and notations, two examples are given and it is shown that even the time-optimal control problem for linear systems with constant coefficients which looked like ''completely solved'' requires a further qualitative investigation of the stability to ''permanent perturbations'' of optimal feedback control. In the second section some basic results of the linear time-optimal control problem are reviewed. The third section deals with the definition of Boltyanskii's ''regular synthesis'' and its connection to Filippov's theory of right-hand side discontinuous differential equations. In the fourth section a theorem is proved concerning the stability to perturbations of time-optimal feedback control for linear systems with scalar control. In the last two sections it is proved that, if the matrix which defines the system has only real eigenvalues or is three-dimensional, the time-optimal feedback control defines a regular synthesis and therefore is stable to perturbations. (author)
Combined feedforward and feedback control of end milling system
F. Cus
2011-03-01
Full Text Available Purpose: Purpose of this paper. An intelligent control system is presented that uses a combination of feedforward and feedback for cutting force control in end milling.Design/methodology/approach: The network is trained by the feedback output that is minimized during training and most control action for disturbance rejection is finally performed by the rapid feedforward action of the network.Findings: The feedback controller corrects for errors caused by external disturbances. The feedforward controller is an artificial neural network (ANN which approximates the inverse dynamics of the machining process.Research limitations/implications: The dynamic architecture of the neural controller is chosen, and the methods for delay time treatment and training network on line are investigated. The controller was designed and tested using a simulator model of the milling process that includes feed drive model and cutting dynamics simulator.Practical implications: An application to cutting force control in end-milling is used to prove the effectiveness of the control scheme and the experiments shows that the dynamic performance of the cutting force control is greatly improved by this neural combined control system.Originality/value: New combined feedforward and feedback control system of end milling system is developed and tested by many experiments. Also a comprehensive user-friendly software package has been developed to monitor the optimal cutting parameters during machining
Design of multivariable feedback control systems via spectral assignment
Mielke, R. R.; Tung, L. J.; Marefat, M.
1983-01-01
The applicability of spectral assignment techniques to the design of multivariable feedback control systems was investigated. A fractional representation design procedure for unstable plants is presented and illustrated with an example. A computer aided design software package implementing eigenvalue/eigenvector design procedures is described. A design example which illustrates the use of the program is explained.
Cross-Layer Adaptive Feedback Scheduling of Wireless Control Systems
Jinxiang Dong
2008-07-01
Full Text Available There is a trend towards using wireless technologies in networked control systems. However, the adverse properties of the radio channels make it difficult to design and implement control systems in wireless environments. To attack the uncertainty in available communication resources in wireless control systems closed over WLAN, a cross-layer adaptive feedback scheduling (CLAFS scheme is developed, which takes advantage of the co-design of control and wireless communications. By exploiting crosslayer design, CLAFS adjusts the sampling periods of control systems at the application layer based on information about deadline miss ratio and transmission rate from the physical layer. Within the framework of feedback scheduling, the control performance is maximized through controlling the deadline miss ratio. Key design parameters of the feedback scheduler are adapted to dynamic changes in the channel condition. An eventdriven invocation mechanism for the feedback scheduler is also developed. Simulation results show that the proposed approach is efficient in dealing with channel capacity variations and noise interference, thus providing an enabling technology for control over WLAN.
Open Problems on Information and Feedback Controlled Systems
Manuel Feito; Cao, Francisco J.
2012-01-01
Feedback or closed-loop control allows dynamical systems to increase their performance up to a limit imposed by the second law of thermodynamics. It is expected that within this limit, the system performance increases as the controller uses more information about the system. However, despite the relevant progresses made recently, a general and complete formal development to justify this statement using information theory is still lacking. We present here the state-of-the-art and the main open...
Bifurcation Analysis of a Discrete Logistic System with Feedback Control
WU Dai-yong
2015-01-01
The paper studies the dynamical behaviors of a discrete Logistic system with feedback control. The system undergoes Flip bifurcation and Hopf bifurcation by using the center manifold theorem and the bifurcation theory. Numerical simulations not only illustrate our results, but also exhibit the complex dynamical behaviors of the system, such as the period-doubling bifurcation in periods 2, 4, 8 and 16, and quasi-periodic orbits and chaotic sets.
On stability theory. [of nonlinear feedback control systems
Safonov, M. G.; Athans, M.
1979-01-01
It is found that under mild assumptions, feedback system stability can be concluded if one can 'topologically separate' the infinite-dimensional function space containing the system's dynamical input-output relations into two regions, one region containing the dynamical input-output relation of the 'feedforward' element of the system and the other region containing the dynamical output-input relation of the 'feedback' element. Nonlinear system stability criteria of both the input-output type and the state-space (Liapunov) type are interpreted in this context. The abstract generality and conceptual simplicity afforded by the topological separation perspective clarifies some of the basic issues underlying stability theory and serves to suggest improvements in existing stability criteria. A generalization of Zames' (1966) conic-relation stability criterion is proved, laying the foundation for improved multivariable generalizations of the frequency-domain circle stability criterion for nonlinear systems.
Vay, J.-L.; Furman, M. A.
2010-12-13
Electron clouds have been shown to trigger fast growing instabilities on proton beams circulating in the SPS, and a feedback system to control the single-bunch instabilities is under active development. We present the latest improvements to the WARP-POSINST simulation framework and feedback model, and its application to the self-consistent simulations of two consecutive bunches interacting with an electron cloud in the SPS. Simulations using an idealized feedback system exhibit adequate mitigation of the instability providing that the cutoff of the feedback bandwidth is at or above 450 MHz. Artifacts from numerical noise of the injected distribution of electrons in the modeling of portions of bunch trains are discussed, and benchmarking of WARP against POSINST and HEADTAIL are presented.
Electron clouds have been shown to trigger fast growing instabilities on proton beams circulating in the SPS, and a feedback system to control the single-bunch instabilities is under active development. We present the latest improvements to the WARP-POSINST simulation framework and feedback model, and its application to the self-consistent simulations of two consecutive bunches interacting with an electron cloud in the SPS. Simulations using an idealized feedback system exhibit adequate mitigation of the instability providing that the cutoff of the feedback bandwidth is at or above 450 MHz. Artifacts from numerical noise of the injected distribution of electrons in the modeling of portions of bunch trains are discussed, and benchmarking of WARP against POSINST and HEADTAIL are presented.
Xu, Wei; Z. Wu, W.; Li, Jing-Yi; He, Duo-Hui; K. Wu, Y.
2013-07-01
To combat electron beam instabilities, a digital bunch-by-bunch transverse feedback (TFB) system has been developed for the Duke storage ring. While it is capable of suppressing transverse beam instabilities for multibunch operation, the TFB system has not been needed for typical operation of the Duke storage ring. To explore the great potential of this system, we have developed beam diagnostic techniques using the TFB, in particular, the TFB based tune measurement techniques. The tune measurement technique allows us to conduct fast chromaticity measurements, compared with the existing chromaticity measurement system using a network analyzer. This new tune measurement system also enables us to measure the bunch tune for multibunch operation of the Duke storage ring. With the TFB based tune measurement system, we have studied the tune stability of the electron beam in the Duke storage ring. This tune system has also been used to calibrate the tune knob for the Duke storage ring.
LHC beam instrumentation detectors and acquisition systems
An overview of some of the detectors and acquisition systems being developed for measuring and controlling beam parameters in the LHC. The two largest systems concern the measurement of beam position, with over 1000 monitors, and beam loss, with over 3000 monitors. For the beam position system a novel wide band time normaliser has been developed to allow bunch-by-bunch 40MHz acquisitions with a dynamic range greater than 30dB and an overall linearity of better than 1%. Also mentioned will be the acquisition system for the fast beam current transformers and the development of CdTe detectors for luminosity monitoring. [author
Modeling mutual feedback between users and recommender systems
Zeng, An; Yeung, Chi Ho; Medo, Matúš; Zhang, Yi-Cheng
2015-07-01
Recommender systems daily influence our decisions on the Internet. While considerable attention has been given to issues such as recommendation accuracy and user privacy, the long-term mutual feedback between a recommender system and the decisions of its users has been neglected so far. We propose here a model of network evolution which allows us to study the complex dynamics induced by this feedback, including the hysteresis effect which is typical for systems with non-linear dynamics. Despite the popular belief that recommendation helps users to discover new things, we find that the long-term use of recommendation can contribute to the rise of extremely popular items and thus ultimately narrow the user choice. These results are supported by measurements of the time evolution of item popularity inequality in real systems. We show that this adverse effect of recommendation can be tamed by sacrificing part of short-term recommendation accuracy.
Modeling mutual feedback between users and recommender systems
Zeng, An; Medo, Matus; Zhang, Yi-Cheng
2015-01-01
Recommender systems daily influence our decisions on the Internet. While considerable attention has been given to issues such as recommendation accuracy and user privacy, the long-term mutual feedback between a recommender system and the decisions of its users has been neglected so far. We propose here a model of network evolution which allows us to study the complex dynamics induced by this feedback, including the hysteresis effect which is typical for systems with non-linear dynamics. Despite the popular belief that recommendation helps users to discover new things, we find that the long-term use of recommendation can contribute to the rise of extremely popular items and thus ultimately narrow the user choice. These results are supported by measurements of the time evolution of item popularity inequality in real systems. We show that this adverse effect of recommendation can be tamed by sacrificing part of short-term recommendation accuracy.
In this paper, we study chaos (lag) synchronization of a new LC chaotic system, which can exhibit not only a two-scroll attractor but also two double-scroll attractors for different parameter values, via three types of state feedback controls: (i) linear feedback control; (ii) adaptive feedback control; and (iii) a combination of linear feedback and adaptive feedback controls. As a consequence, ten families of new feedback control laws are designed to obtain global chaos lag synchronization for τ < 0 and global chaos synchronization for τ = 0 of the LC system. Numerical simulations are used to illustrate these theoretical results. Each family of these obtained feedback control laws, including two linear (adaptive) functions or one linear function and one adaptive function, is added to two equations of the LC system. This is simpler than the known synchronization controllers, which apply controllers to all equations of the LC system. Moreover, based on the obtained results of the LC system, we also derive the control laws for chaos (lag) synchronization of another new type of chaotic system
Output Feedback Control for a Class of Nonlinear Systems
Keylan Alimhan; Hiroshi Inaba
2006-01-01
This paper studies the global stabilization problem by an output controller for a family of uncertain nonlinear systems satisfying some relaxed triangular-type conditions and with dynamics which may not be exactly known. Using a feedback domination design method, we explicitly construct a dynamic output compensator which globally stabilizes such an uncertain nonlinear system. The usefulness of our result is illustrated with an example.
Autonomous learning by simple dynamical systems with delayed feedback
Kaluza, Pablo; Mikhailov, Alexander S.
2014-09-01
A general scheme for the construction of dynamical systems able to learn generation of the desired kinds of dynamics through adjustment of their internal structure is proposed. The scheme involves intrinsic time-delayed feedback to steer the dynamics towards the target performance. As an example, a system of coupled phase oscillators, which can, by changing the weights of connections between its elements, evolve to a dynamical state with the prescribed (low or high) synchronization level, is considered and investigated.
Non-Linear Dynamic Deformation of a Piezothermoelastic Laminate with Feedback Control System
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.
On reliable control system designs with and without feedback reconfigurations
Birdwell, J. D.; Castanon, D. A.; Athans, M.
1979-01-01
This paper contains an overview of a theoretical framework for the design of reliable multivariable control systems, with special emphasis on actuator failures and necessary actuator redundancy levels. Using a linear model of the system, with Markovian failure probabilities and quadratic performance index, an optimal stochastic control problem is posed and solved. The solution requires the iteration of a set of highly coupled Riccati-like matrix difference equations; if these converge one has a reliable design; if they diverge, the design is unreliable, and the system design cannot be stabilized. In addition, it is shown that the existence of a stabilizing constant feedback gain and the reliability of its implementation is equivalent to the convergence properties of a set of coupled Riccati-like matrix difference equations. In summary, these results can be used for offline studies relating the open loop dynamics, required performance, actuator mean time to failure, and functional or identical actuator redundancy, with and without feedback gain reconfiguration strategies.
Stability and Bifurcation in Magnetic Flux Feedback Maglev Control System
Wen-Qing Zhang
2013-01-01
Full Text Available Nonlinear properties of magnetic flux feedback control system have been investigated mainly in this paper. We analyzed the influence of magnetic flux feedback control system on control property by time delay and interfering signal of acceleration. First of all, we have established maglev nonlinear model based on magnetic flux feedback and then discussed hopf bifurcation’s condition caused by the acceleration’s time delay. The critical value of delayed time is obtained. It is proved that the period solution exists in maglev control system and the stable condition has been got. We obtained the characteristic values by employing center manifold reduction theory and normal form method, which represent separately the direction of hopf bifurcation, the stability of the period solution, and the period of the period motion. Subsequently, we discussed the influence maglev system on stability of by acceleration’s interfering signal and obtained the stable domain of interfering signal. Some experiments have been done on CMS04 maglev vehicle of National University of Defense Technology (NUDT in Tangshan city. The results of experiments demonstrate that viewpoints of this paper are correct and scientific. When time lag reaches the critical value, maglev system will produce a supercritical hopf bifurcation which may cause unstable period motion.
Spiral kicker for the beam abort system
Martin, R.L.
1983-01-01
A brief study was carried out to determine the feasibility of a special kicker to produce a damped spiral beam at the beam dump for the beam abort system. There appears to be no problem with realizing this concept at a reasonably low cost.
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.
Parameterized design of nonlinear feedback controllers for servo positioning systems
Cheng Guoyang; Jin Wenguang
2006-01-01
To achieve fast, smooth and accurate set point tracking in servo positioning systems, a parameterized design of nonlinear feedback controllers is presented, based on a so-called composite nonlinear feedback (CNF) control technique. The controller designed here consists of a linear feedback part and a nonlinear part. The linear part is responsible for stability and fast response of the closed-loop system. The nonlinear part serves to increase the damping ratio of closed-loop poles as the controlled output approaches the target reference. The CNF control brings together the good points of both the small and the large damping ratio cases, by continuously scheduling the damping ratio of the dominant closed-loop poles and thus has the capability for superior transient performance, i.e. a fast output response with low overshoot. In the presence of constant disturbances, an integral action is included so as to remove the static bias. An explicitly parameterized controller is derived for servo positioning systems characterized by second-order model. Practical application in a micro hard disk drive servo system is then presented, together with some discussion of the rationale and characteristics of such design. Simulation and experimental results demonstrate the effectiveness of this control design methodology.
Mitigation of ground motion effects via feedback systems in the Compact Linear Collider
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 ...
Transverse feedback systems for the PEP-II B-factory
Growth rates of coherent beam oscillations are faster than the natural damping mechanisms for the parameters of the PEP-II B-factory storage rings at nominal currents, even with damping of cavity higher order modes (HOM's). With 165 8 bunches separated by 4.2 ns, and a large current of up to 3A (2.14 A nominal in the low energy ring), many coupled-bunch modes are excited by the resistive wall impedance and cavity higher order mode impedance. Fastest growth times of transverse rigid-bunch modes of approximately 300 ps are expected, two orders of magnitude faster than the radiation damping time. We will provide broadband, bunch-by-bunch feedback to suppress this coherent motion of the beam. Experience gained with a prototype system, installed and successfully operating at the LBNL Advanced Light Source (ALS), has been used extensively in developing the design of the PEP-II systems
Decentralized stabilization of complex systems with delayed feedback
Bakule, Lubomír; de la Sen, M.; Papík, Martin; Rehák, Branislav
Shanghai: International Federation of Automatic Control , 2013, s. 31-36. (Large Scale Complex Systems Theory and Applications. Volume 13). ISBN 978-3-902823-39-7. ISSN 1474-6670. [IFAC Symposium of Large Scale Complex Systems /13./ (LSS 2013). Shanghai (CN), 07.07.2013-10.07.2013] R&D Projects: GA ČR GA13-02149S; GA MŠk(CZ) LG12014; GA MŠk(CZ) LG12008 Institutional support: RVO:67985556 Keywords : decentralized control * symmetric interconnected systems * delayed feedback Subject RIV: BC - Control Systems Theory http://library.utia.cas.cz/separaty/2013/AS/bakule-0393028.pdf
Multiple-pattern stability in a photorefractive feedback system
Schwab, M.; Denz, C.; Saffman, M.
1999-01-01
diffraction lengths. For the same values of the control parameters square, rectangular, or squeezed hexagonal patterns are found alternating in time. Besides these pure states, we found a number of different mixed-pattern states. We review the linear stability analysis for this system and show that the......We report on the observation of a multiple-pattern stability region in a photorefractive single-feedback system. Whereas hexagonal patterns are predominant for feedback with positive diffraction length we show that a variety of stable non-hexagonal patterns are generated for certain negative...... special shape of the threshold curves in the investigated parameter region gives a first explanation for the occurrence of a multiple-pattern region....
Digital bunch-by-bunch transverse feedback system at SSRF
无
2011-01-01
In order to suppress multi-bunch couple instabilities caused by transverse impedance, a bunch-by-bunch transverse feedback system based on a FPGA digital processor is commissioned at SSRF storage ring. The RF front end has two COD pre-rejected attenuators for increasing the system arrangement and signal noise ratio, and the 3*RF Local signal comes from the BPM’s sum signal using a FIR filter for avoiding the effect of longitudinal oscillation. The digital processor receives the coupled horizontal and vertical oscillation signals in the base band and transforms the coupled signals to the horizontal and vertical feedback signals with two series double-zeroes FIR filters. A matlab GUI is applied for producing the FIR coefficients when the tune is shifted. The horizontal and vertical Kickers have a special design for increasing the shunt impedance. Then the multi-bunch instabilities are suppressed respectively and the minimum damping time is about 0.4 ms.
Integration of the Longitudinal Feedback System in NSRRC
An operation version of longitudinal feedback baseband processing electronics was implemented. The system consists of a bunch phase detector, a 500-MS/s analog-to-digital converter and demultiplexer module (ADC/DEMUX), DSP modules, a digital-to-analog converter and multiplexer module (DAC/MUX), and an RF modulator. The ADC/DEMUX unit has a fast ADC that digitizes the bunch phase signal. The down-sampled phase error data of each bunch are then distributed to the DSP boards to perform filtering and applied control rule. In the DAC/MUX, bunch kick signals are converted into analog signals for bunch phase feedback. Design and implementation of the system will be summarized in this report
Design and Simulation of PMSM Feedback Linearization Control System
Song, Xiao-jing
2013-01-01
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 outpu...
Digital feedback system using μTCA for DRFS
The test of distributed RF scheme (DRFS) for ILC was performed at the superconducting RF test facility in KEK (KEK-STF). The vector-sum control for two cavities was done by using the digital feedback system using the μTCA. A correction of a large sag due to electrical power source and IIR filter which is also applied as a cavity simulator was installed. The measurement of field stability and the performance are reported. (author)
Challenges in the Implementation of Measurement Feedback Systems.
de Jong, Kim
2016-05-01
This commentary on the articles published in the special section on the development and implementation of measurement feedback systems (MFSs) discusses three challenging themes in the process of MFS implementation: design and planning, organizational context, and sustainability and unintended consequences. It is argued that the implementation of MFSs is complex, but is an important step in improving outcomes in routine care for children and young persons. PMID:26518779
Virtual Chimera States for Delayed-Feedback Systems
Larger, Laurent; PENKOVSKYI, Bogdan; Maistrenko, Yuri
2013-01-01
International audience Time-delayed systems are found to display remarkable temporal patterns the dynamics of which split into regular and chaotic components repeating at the interval of a delay. This novel long-term behavior for delay dynamics results from strongly asymmetric nonlinear delayed feedback driving a highly damped harmonic oscillator dynamics. In the corresponding virtual space-time representation, the behavior is found to develop as a chimeralike state, a new paradigmatic obj...
Study of an accelerating superconducting module and its feedback loop systems for the MYRRHA project
The MYRRHA ( Multi-purpose hybrid Research Reactor for High-tech Applications ) project aims at constructing an accelerator driven system (ADS) demonstrator (50 a 100 MWth) to explore the feasibility of nuclear waste transmutation. Such a subcritical reactor requires an extremely reliable accelerator which delivers a CW high power protons beam (600 MeV, 4 mA). The reference solution for this machine is a superconducting linear accelerator. This thesis presents the work - undertaken at IPN Orsay in October 2008 - on the study of a prototypical superconducting module and the feedback control systems of its cavity for the high energy part of the MYRRHA linac. First, the optimization and the design of 5-cell elliptical cavities (β=0,65), operating at 704.4 MHz, are presented. Then, the experimental work focuses on a reliability oriented study of the 'cryo-module' which hold a prototypical 5-cell cavity (β=0,47). In this study, the dynamic behavior of the fast tuning system of the cavity was measured and qualified. The 'field flatness' issue in 'low beta' multi-cell cavity was also brought to light. Finally, a fault-tolerance analysis of the linac was carried out. Toward this goal, a model of the cavity, its RF feedback loop system and its tuning system feedback loop was developed. This study enabled to determine the RF power needs, the tuning system requirements and as well as to demonstrate the feasibility of fast fault-recovery scenarios to minimize the number of beam interruptions in the MYRRHA linac. (author)
A simple electron-beam lithography system
Mølhave, Kristian; Madsen, Dorte Nørgaard; Bøggild, Peter
2005-01-01
A large number of applications of electron-beam lithography (EBL) systems in nanotechnology have been demonstrated in recent years. In this paper we present a simple and general-purpose EBL system constructed by insertion of an electrostatic deflector plate system at the electron-beam exit of the...... be used to write three-dimensional nanostructures by electron-beam deposition. (C) 2004 Elsevier B.V. All rights reserved....
BEAM CONTAINMENT SYSTEM FOR NSLS-II
The shielding design for the NSLS-II will provide adequate protection for the full injected beam loss in two periods of the ring around the injection point, but the remainder of the ring is shielded for lower losses of (le) 10% full beam. This will require a system to insure that beam losses don't exceed these levels for a period of time that could cause excessive radiation levels outside the shield walls. This beam containment system will measure, provide a level of control and alarm indication of the beam power losses along the beam path from the source (e-gun, linac) thru the injection system and the storage ring. This system will consist of collimators that will provide limits to (and potentially to measure) the beam miss-steering and control the loss points of the charge and monitors that will measure the average beam current losses along the beam path and alarm when this beam power loss exceeds the level set by the shielding specifications. This will require some new ideas in beam loss detection capability and collimation. The initial planning and R and D program will be presented.
The upgraded rf system for the AGS and high intensity proton beams
Brennan, J.M. [Brookhaven National Lab., Upton, NY (United States). AGS Dept.
1995-05-01
The AGS has been upgraded over the past three years to produce a record beam intensity of 6 {times} 10{sup 13} protons per pulse for the fixed-target physics program. The major elements of the upgrade are: the new 1.5 GeV Booster synchrotron, the main magnet power supply, a high frequency longitudinal dilution cavity, a feedback damper for transverse instabilities, a fast gamma transition jump system, and a new high-power rf system. The new rf system and its role in achieving the high intensity goal are the subjects of this report. The rf system is heavily beam loaded, with 7 Amps of rf current in the beam and a peak power of 0.75 MW delivered to the beam by ten cavities. As an example of the scale of beam loading, at one point in the acceleration cycle the cavities are operated at 1.5 kV/gap; whereas, were it not for the new power amplifiers, the beam-induced voltage on the cavities would be over 25 kV/gap. The upgraded rf system, comprising: new power amplifiers, wide band rf feedback, improved cavities, and new low-level beam control electronics, is described. Results of measurements with beam, which characterize the system`s performance, are presented. A typical high intensity acceleration cycle is described with emphasis on the key challenges of beam loading.
Linear quantum feedback networks
Gough, J. E.; Gohm, R.; Yanagisawa, M.
2008-12-01
The mathematical theory of quantum feedback networks has recently been developed [J. Gough and M. R. James, e-print arXiv:0804.3442v2] for general open quantum dynamical systems interacting with bosonic input fields. In this article we show, for the special case of linear dynamical Markovian systems with instantaneous feedback connections, that the transfer functions can be deduced and agree with the algebraic rules obtained in the nonlinear case. Using these rules, we derive the transfer functions for linear quantum systems in series, in cascade, and in feedback arrangements mediated by beam splitter devices.
Development of bunch by bunch transverse feedback system at Hefei light source
This paper has introduced the development of the transverse bunch-by-bunch measurement and feedback system, including the experiment of damping the coupled bunch instability. Some key technologies on the system have been introduced: the vector calculation module as a signal processing module used to adjust the phase of the feedback signals, the feedback kicker cavity and the notch filter used to filter the DC component and revolution frequencies component in a signal and save the feedback power. The result of the feedback experiment is mentioned: the instability oscillation was damped when the feedback system was on. (authors)
Feedback compensation network design for KAPP reactor regulating system
The reactor power regulating system based on coolant differential temperature across the boiler is inaccurate and sluggish because of the transport delays and time constants associated with temperature measurement. Moreover the control system cannot correct promptly the disturbances transmitted by the secondary system. Above problems can be easily overcome by the reactor control system based on neutron flux measured by the out of core ionisation chambers. The report describes the design and analysis of feedback compensation network based on neutron flux measurement. Closed loop system stability analysis of Kakrapar Atomic Power Plant has been made based on linearised transfer function models of sub-system, to achieve good gain and phase control margins. The control system responses have been tested using reactor functional simulator. The design has been verified by sampled data system analysis using Z transform of the reactor mathematical model. (author). 21 refs., 1 tab
The upgraded rf system for the AGS and high intensity proton beams
The AGS has been upgraded over the past three years to produce a record beam intensity of 6 x 1013 protons per pulse for the fixed-target physics program. The major elements of the upgrade are: the new 1.5 GeV Booster synchrotron, the main magnet power supply, a high frequency longitudinal dilution cavity, a feedback damper for transverse instabilities, a fast gamma transition jump system, and a new high-power rf system. The new rf system and its role in achieving the high intensity goal are the subjects of this report. The rf system is heavily beam loaded, with 7 Amps of rf current in the beam and a peak power of 0.75 MW delivered to the beam by ten cavities. As an example of the scale of beam loading, at one point in the acceleration cycle the cavities are operated at 1.5 kV/gap; whereas, were it not for the new power amplifiers, the beam-induced voltage on the cavities would be over 25 kV/gap. The upgraded rf system, comprising: new power amplifiers, wide band rf feedback, improved cavities, and new low-level beam control electronics, is described. Results of measurements with beam, which characterize the system's performance, are presented. A typical high intensity acceleration cycle is described with emphasis on the key challenges of beam loading