Sample records for macroeconomic feedback mechanism

  1. Analyzing Fuel Saving Opportunities through Driver Feedback Mechanisms...

    Office of Environmental Management (EM)

    Fuel Saving Opportunities through Driver Feedback Mechanisms 2011 DOE Hydrogen and Fuel Cells Program, and Vehicle Technologies Program Annual Merit Review and Peer...

  2. autocrine feedback mechanism: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    A feedback mechanism based on hamiltonian tracking Quantum Physics (arXiv) Summary: Enviroment - caused dissipation disrupts the hamiltonian evolution of all quantum systems...

  3. Macroeconomics: A Survey of Laboratory Research Department of Economics

    E-Print Network [OSTI]

    Tesfatsion, Leigh

    to laboratory experiments involving human subjects but rather to computational experiments using calibrated Welcome Abstract This chapter surveys laboratory experiments addressing macroeconomic phenomena. The first and mechanisms for resolving these problems. Part three looks at experiments in specific macroeconomic sectors

  4. Feedback mechanism for smart nozzles and nebulizers

    DOE Patents [OSTI]

    Montaser, Akbar [Potomac, MD; Jorabchi, Kaveh [Arlington, VA; Kahen, Kaveh [Kleinburg, CA

    2009-01-27T23:59:59.000Z

    Nozzles and nebulizers able to produce aerosol with optimum and reproducible quality based on feedback information obtained using laser imaging techniques. Two laser-based imaging techniques based on particle image velocimetry (PTV) and optical patternation map and contrast size and velocity distributions for indirect and direct pneumatic nebulizations in plasma spectrometry. Two pulses from thin laser sheet with known time difference illuminate droplets flow field. Charge coupled device (CCL)) captures scattering of laser light from droplets, providing two instantaneous particle images. Pointwise cross-correlation of corresponding images yields two-dimensional velocity map of aerosol velocity field. For droplet size distribution studies, solution is doped with fluorescent dye and both laser induced florescence (LIF) and Mie scattering images are captured simultaneously by two CCDs with the same field of view. Ratio of LIF/Mie images provides relative droplet size information, then scaled by point calibration method via phase Doppler particle analyzer.

  5. Feedback Mechanism for Microtubule Length Regulation by Stathmin Gradients

    E-Print Network [OSTI]

    Maria Zeitz; Jan Kierfeld

    2014-12-09T23:59:59.000Z

    We formulate and analyze a theoretical model for the regulation of microtubule (MT) polymerization dynamics by the signaling proteins Rac1 and stathmin. In cells, the MT growth rate is inhibited by cytosolic stathmin, which, in turn, is inactivated by Rac1. Growing MTs activate Rac1 at the cell edge, which closes a positive feedback loop. We investigate both tubulin sequestering and catastrophe promotion as mechanisms for MT growth inhibition by stathmin. For a homogeneous stathmin concentration in the absence of Rac1, we find a switch-like regulation of the MT mean length by stathmin. For constitutively active Rac1 at the cell edge, stathmin is deactivated locally, which establishes a spatial gradient of active stathmin. In this gradient, we find a stationary bimodal MT length distributions for both mechanisms of MT growth inhibition by stathmin. One subpopulation of the bimodal length distribution can be identified with fast growing and long pioneering MTs in the region near the cell edge, which have been observed experimentally. The feedback loop is closed through Rac1 activation by MTs. For tubulin sequestering by stathmin, this establishes a bistable switch with two stable states: one stable state corresponds to upregulated MT mean length and bimodal MT length distributions, i.e., pioneering MTs; the other stable state corresponds to an interrupted feedback with short MTs. Stochastic effects as well as external perturbations can trigger switching events. For catastrophe promoting stathmin we do not find bistability.

  6. Mechanical Feedback: From stellar wind bubbles to starbursts

    E-Print Network [OSTI]

    M. S. Oey; C. J. Clarke; P. Massey

    2001-03-20T23:59:59.000Z

    The current understanding of mechanical feedback is reviewed by evaluating the standard, adiabatic model for shell formation and evolution. This model is relevant to phenomena ranging from individual stellar-wind bubbles to galactic superwinds, forming the basis for our understanding of the multiphase ISM, IGM, and galactic evolutionary processes. Although significant discrepancies between the model and observation have been identified, to date there are none that require a fundamental revision. A variety of evidence, ranging over three orders of magnitude in spatial scale, is broadly consistent with the standard model. This includes kinematics of individual objects, observations of hot gas, the size distribution of HI shells, and outflow rates from starburst galaxies. However, some of the most pressing issues relating to shell evolution are still outstanding and obstruct efforts to resolve key questions like the fate of the hot gas.

  7. Essays in macroeconomics

    E-Print Network [OSTI]

    Nenov, Plamen T. (Plamen Toshkov)

    2012-01-01T23:59:59.000Z

    This thesis examines questions in macroeconomics motivated by the 2007-2008 financial crisis and its aftermath. Chapter 1 studies the impact of a housing bust on regional labor reallocation and the labor market. I document ...

  8. User Monitor & Feedback Mechanism for Social Scientific Study on Laptop Energy Reduction

    E-Print Network [OSTI]

    Stamp, Mark

    change among laptop users via interactive energy-usage feedback with college students as the initiali User Monitor & Feedback Mechanism for Social Scientific Study on Laptop Energy Reduction SCIENTIFIC STUDY ON LAPTOP ENERGY REDUCTION by Namrata Buddhadev APPROVED FOR THE DEPARTMENT OF COMPUTER

  9. Theory and calculations of synchrotron instabilities and feedback-mechanism

    SciTech Connect (OSTI)

    Meijssen, T.E.M.

    1981-08-12T23:59:59.000Z

    The properties of the phenomenon synchrotron radiation are given with general theory on the basic processes and betatron and synchrotron oscillations. A more extended theoretical view at transverse instabilities and the influence of a damping feedback system are discussed. The longitudinal case is covered. For the calculations on the longitudinal case with M equally spaced pointbunches, with N electrons each, in the storage ring, the parasitic modes of the radio-frequency cavity were measured. A description of this is given. The values of damping rates of the longitudinal feedback system found, are as expected, but too low to damp the longitudinal instabilities calculated. This might be caused by the input data. The calculated growth rates are very sensitive to changes in frequency and width of the parasitic modes, which were measured under conditions differing slightly from the operating conditions.

  10. Version pressure feedback mechanisms for speculative versioning caches

    DOE Patents [OSTI]

    Eichenberger, Alexandre E.; Gara, Alan; O'Brien, Kathryn M.; Ohmacht, Martin; Zhuang, Xiaotong

    2013-03-12T23:59:59.000Z

    Mechanisms are provided for controlling version pressure on a speculative versioning cache. Raw version pressure data is collected based on one or more threads accessing cache lines of the speculative versioning cache. One or more statistical measures of version pressure are generated based on the collected raw version pressure data. A determination is made as to whether one or more modifications to an operation of a data processing system are to be performed based on the one or more statistical measures of version pressure, the one or more modifications affecting version pressure exerted on the speculative versioning cache. An operation of the data processing system is modified based on the one or more determined modifications, in response to a determination that one or more modifications to the operation of the data processing system are to be performed, to affect the version pressure exerted on the speculative versioning cache.

  11. Essays in macroeconomics and experiments

    E-Print Network [OSTI]

    Shurchkov, Olga

    2008-01-01T23:59:59.000Z

    This dissertation consists of four chapters on empirical and experimental macroeconomics and other experimental topics. Chapter 1 uses a laboratory experiment to test the predictions of a dynamic global game designed to ...

  12. Essays in open economy macroeconomics

    E-Print Network [OSTI]

    Ghosh, Indradeep, Ph. D. Massachusetts Institute of Technology

    2007-01-01T23:59:59.000Z

    This thesis is a collection of two essays on open economy macroeconomics. The first essay is on imperfect asset substitutability and current account dynamics. It is divided into four chapters. The first chapter in this ...

  13. Term Structure Dynamics with Macroeconomic Factors 

    E-Print Network [OSTI]

    Park, Ha-Il

    2011-02-22T23:59:59.000Z

    Affine term structure models (ATSMs) are known to have a trade-off in predicting future Treasury yields and fitting the time-varying volatility of interest rates. First, I empirically study the role of macroeconomic variables ...

  14. Essays in macroeconomics and corporate finance

    E-Print Network [OSTI]

    Goldberg, Jonathan E. (Jonathan Elliot)

    2011-01-01T23:59:59.000Z

    This thesis examines questions at the intersection of macroeconomics and finance. Chapter 1 studies the persistent effects of a decrease in firms' ability to borrow. I develop a tractable model of deleveraging that emphasizes ...

  15. Essays on political institutions and macroeconomics

    E-Print Network [OSTI]

    Yared, Pierre

    2007-01-01T23:59:59.000Z

    This dissertation consists of three chapters on the interaction of political institutions and macroeconomic activity in dynamic environments. Chapter 1 studies the optimal management of taxes and debt in a framework which ...

  16. Essays in International Macroeconomics and Forecasting

    E-Print Network [OSTI]

    Bejarano Rojas, Jesus Antonio

    2012-10-19T23:59:59.000Z

    This dissertation contains three essays in international macroeconomics and financial time series forecasting. In the first essay, I show, numerically, that a two-country New-Keynesian Sticky Prices model, driven by monetary and productivity shocks...

  17. APEX-CHAMP+ high-J CO observations of low-mass young stellar objects: IV. Mechanical and radiative feedback

    E-Print Network [OSTI]

    Y?ld?z, Umut A; van Dishoeck, Ewine F; Hogerheijde, Michiel R; Karska, Agata; Belloche, Arnaud; Endo, Akira; Frieswijk, Wilfred; Güsten, Rolf; van Kempen, Tim A; Leurini, Silvia; Nagy, Zsofia; Pérez-Beaupuits, Juan-Pablo; Risacher, Christophe; van der Marel, Nienke; van Weeren, Reinout J; Wyrowski, Friedrich

    2015-01-01T23:59:59.000Z

    During the embedded stage of star formation, bipolar molecular outflows and UV radiation from the protostar are important feedback processes. Our aim is to quantify the feedback, mechanical and radiative, for a large sample of low-mass sources. The outflow activity is compared to radiative feedback in the form of UV heating by the accreting protostar to search for correlations and evolutionary trends. Large-scale maps of 26 young stellar objects, which are part of the Herschel WISH key program are obtained using the CHAMP+ instrument on the APEX (12CO and 13CO 6-5), and the HARP-B instrument on the JCMT (12CO and 13CO 3-2). Maps are used to determine outflow parameters and envelope models are used to quantify the amount of UV-heated gas and its temperature from 13CO 6-5 observations. All sources in our sample show outflow activity and the outflow force, F_CO, is larger for Class 0 sources than for Class I sources, even if their luminosities are comparable. The outflowing gas typically extends to much greater ...

  18. CGILS: Results from the First Phase of an International Project to Understand the Physical Mechanisms of Low Cloud Feedbacks in Single Column Models

    SciTech Connect (OSTI)

    Zhang, Minghua; Bretherton, Christopher S.; Blossey, Peter; Austin, Phillip A.; Bacmeister, J.; Bony, Sandrine; Brient, Florent; Cheedela, Suvarchal K.; Cheng, Anning; Del Genio, Anthony D.; De Roode, Stephan R.; Endo , Satoshi; Franklin, Charmaine N.; Golaz, Jean-Christophe; Hannay, Cecile; Heus, Thijs; Isotta, Francesco A.; Jean-Louis, Dufresne; Kang, In-Sik; Kawai, Hideaki; Koehler, M.; Larson, Vincent E.; Liu, Yangang; Lock, Adrian; Lohmann, U.; Khairoutdinov, Marat; Molod, Andrea M.; Neggers, Roel; Rasch, Philip J.; Sandu, Irina; Senkbeil, Ryan; Siebesma, A. P.; Siegenthaler-Le Drian, Colombe; Stevens, Bjorn; Suarez, Max; Xu, Kuan-Man; Von Salzen, Knut; Webb, Mark; Wolf, Audrey; Zhao, M.

    2013-12-26T23:59:59.000Z

    Large Eddy Models (LES) and Single Column Models (SCM) are used in a surrogate climate change 101 to investigate the physical mechanism of low cloud feedbacks in climate models. Enhanced surface-102 driven boundary layer turbulence and shallow convection in a warmer climate are found to be 103 dominant mechanisms in SCMs.

  19. WAGES, FLEXIBLE EXCHANGE RATES, AND MACROECONOMIC POLICY*

    E-Print Network [OSTI]

    WAGES, FLEXIBLE EXCHANGE RATES, AND MACROECONOMIC POLICY* JEFFREY SACHS In an open economy with a floaLing exchange rate, the efficacy of fiscal and monetary policy depends fundamentally on the wage rate depreciation, while fiscal expansion has no output effect. These results hold only when real wages

  20. NBER WORKING PAPER SERIES MACROECONOMIC INTERDEPENDENCE OF

    E-Print Network [OSTI]

    .S.; (2) the macroeco- nomic implications of a protectionist tariff imposed by the U.S.; and (3) the scope be the macroeconomic implications of a protectionist tariff imposed by the U.S.? Finally, what is the scope for policy

  1. Emerging Economies, Trade Policy, and Macroeconomic Shocks

    E-Print Network [OSTI]

    Bown, Chad P.; Crowley, Meredith A.

    2014-05-09T23:59:59.000Z

    and across countries – as to how constrained these emerging economies are by WTO disciplines over their applied import tariff policies. Argentina, India, Malaysia, Philippines and Thailand, for example, each have years for which there are major changes... 0 Emerging Economies, Trade Policy, and Macroeconomic Shocks Chad P. Bown† The World Bank Meredith A. Crowley‡ University of Cambridge This version: March 2014 Abstract This paper estimates the impact of aggregate...

  2. Thermal-chemical-mechanical feedback during fluid-rock interactions: Implications for chemical transport and scales of equilibria in the crust

    SciTech Connect (OSTI)

    Dutrow, Barbara

    2008-08-13T23:59:59.000Z

    Our research evaluates the hypothesis that feedback amongst thermal-chemical-mechanical processes operative in fluid-rock systems alters the fluid flow dynamics of the system which, in turn, affects chemical transport and temporal and spatial scales of equilibria, thus impacting the resultant mineral textural development of rocks. Our methods include computational experimentation and detailed analyses of fluid-infiltrated rocks from well-characterized terranes. This work focuses on metamorphic rocks and hydrothermal systems where minerals and their textures are utilized to evaluate pressure (P), temperature (T), and time (t) paths in the evolution of mountain belts and ore deposits, and to interpret tectonic events and the timing of these events. Our work on coupled processes also extends to other areas where subsurface flow and transport in porous media have consequences such as oil and gas movement, geothermal system development, transport of contaminants, nuclear waste disposal, and other systems rich in fluid-rock reactions. Fluid-rock systems are widespread in the geologic record. Correctly deciphering the products resulting from such systems is important to interpreting a number of geologic phenomena. These systems are characterized by complex interactions involving time-dependent, non-linear processes in heterogeneous materials. While many of these interactions have been studied in isolation, they are more appropriately analyzed in the context of a system with feedback. When one process impacts another process, time and space scales as well as the overall outcome of the interaction can be dramatically altered. Our goals to test this hypothesis are: to develop and incorporate algorithms into our 3D heat and mass transport code to allow the effects of feedback to be investigated numerically, to analyze fluid infiltrated rocks from a variety of terranes at differing P-T conditions, to identify subtle features of the infiltration of fluids and/or feedback, and to quantify the importance of feedback in complex fluid-rock systems and its affects on time and space scales and rates of reaction. We have made significant contributions toward understanding feedback and its impacts by numerical experimentation using 3D computational modeling of fluid-rock systems and by chemical and textural analyses of fluid-infiltrated rocks.

  3. Long Run Macroeconomic Relations in the Global Economy

    E-Print Network [OSTI]

    Dees, S; Holly, Sean; Pesaran, M Hashem; Smith, L Vanessa

    This paper focuses on testing long run macroeconomic relations for interest rates, equity, prices and exchange rates within a model of the global economy. It considers a number of plausible long run relationships suggested by arbitrage in financial...

  4. 14.454 Macroeconomic Theory IV, Fall 2004

    E-Print Network [OSTI]

    Caballero, Ricardo

    This half-term course covers the macroeconomic implications of imperfections in labor markets, goods markets, credit and financial markets. The role of nominal rigidities is also an area of focus.

  5. Three essays on empirical macroeconomics and financial markets

    E-Print Network [OSTI]

    Chen, Lili

    2012-08-21T23:59:59.000Z

    This dissertation consists of three essays on empirical macroeconomics and financial markets in the United States. Although they can be considered as three independent essays, their findings are connected with each other ...

  6. 14.452 Macroeconomic Theory II, Spring 2002

    E-Print Network [OSTI]

    Blanchard, Olivier (Olivier J.)

    The basic machines of macroeconomics. Ramsey, Solow, Samuelson-Diamond, RBCs, ISLM, Mundell-Fleming, Fischer-Taylor. How they work, what shortcuts they take, and how they can be used. Half-term subject. From the course ...

  7. Feedback cooling of a single trapped ion

    E-Print Network [OSTI]

    Pavel Bushev; Daniel Rotter; Alex Wilson; Francois Dubin; Christoph Becher; Juergen Eschner; Rainer Blatt; Viktor Steixner; Peter Rabl; Peter Zoller

    2005-09-19T23:59:59.000Z

    Based on a real-time measurement of the motion of a single ion in a Paul trap, we demonstrate its electro-mechanical cooling below the Doppler limit by homodyne feedback control (cold damping). The feedback cooling results are well described by a model based on a quantum mechanical Master Equation.

  8. An Econometric Model of the Yield Curve With Macroeconomic Jump Effects

    E-Print Network [OSTI]

    Piazzesi, Monika

    2001-01-01T23:59:59.000Z

    Kenneth Singleton (1997). “An Econometric Model of the TermDiscretely-Sampled Data. ” Econometric Theory 4, pp. 231-An Econometric Model of the Yield Curve with Macroeconomic

  9. Evolutionary Optimization of Feedback Controllers for Thermoacoustic Instabilities

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Evolutionary Optimization of Feedback Controllers for Thermoacoustic Instabilities Nikolaus Hansen prone to thermoacoustic instabilities which arise due to a feedback loop involving fluctua- tions in acoustic pressure, velocity and heat release. Thermoacoustic instabilities may cause mechanical damage

  10. Feedback-assisted ponderomotive squeezing

    E-Print Network [OSTI]

    David Vitali; Paolo Tombesi

    2010-12-11T23:59:59.000Z

    We analyze how the radiation pressure interaction between a mechanical element and an intensely driven optical cavity mode can be exploited for generating squeezed light. We study in particular how the performance of the optomechanical device can be improved when a homodyne-based feedback loop is added to control the motion of the mechanical element of the system. We show that, when driving the cavity at resonance, an appropriate proportional feedback control is able to improve the generation of ponderomotive squeezing, which should be detectable with state-of-the-art apparatuses.

  11. Applications of Feedback Control in Quantum Systems

    E-Print Network [OSTI]

    Kurt Jacobs

    2006-05-02T23:59:59.000Z

    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 optimal control theory can be applied directly to quantum systems. In addition to noise reduction and stabilization, an important application of feedback in quantum systems is adaptive measurement, and we discuss the various applications of adaptive measurements. We finish by describing specific examples of the application of feedback control to cooling and state-preparation in nano-electro-mechanical systems and single trapped atoms.

  12. Self-regulated growth of supermassive black holes by a dual jet/heating AGN feedback mechanism: methods, tests and implications for cosmological simulations

    E-Print Network [OSTI]

    Dubois, Yohan; Slyz, Adrianne; Teyssier, Romain

    2011-01-01T23:59:59.000Z

    We develop a new sub-grid model for the growth of supermassive Black Holes (BHs) and their associated Active Galactic Nuclei (AGN) feedback in hydrodynamical cosmological simulations. Assuming that BHs are created in the early stages of galaxy formation, they grow by mergers and accretion of gas at a Eddington-limited Bondi accretion rate. However this growth is regulated by AGN feedback which we model using two different modes: a quasar-heating mode when accretion rates onto the BHs are comparable to the Eddington rate, and a radio-jet mode at lower accretion rates. In other words, our feedback model deposits energy as a succession of thermal bursts and jet outflows depending on the properties of the gas surrounding the BHs. We assess the plausibility of such a model by comparing our results to observational measurements of the coevolution of BHs and their host galaxy properties, and check their robustness with respect to numerical resolution. We show that AGN feedback must be a crucial physical ingredient f...

  13. Corrective Feedback and Teacher Development

    E-Print Network [OSTI]

    Ellis, Rod

    2009-01-01T23:59:59.000Z

    types of corrective feedback on ESL student writing. Journaland implicit negative feedback: An empirical study of theof written corrective feedback types. English Language

  14. Transportation technology transitions and macroeconomic growth -- Contemporary evidence

    SciTech Connect (OSTI)

    Santini, D.J.

    1994-12-31T23:59:59.000Z

    This paper presents international and temporal extensions of evidence for a theory developed by the author concerning the interaction of transportation technology transitions and macroeconomic growth. The period 1970 to the present is examined for the nations of Japan, the US, and Europe (France, Germany, Italy and the United Kingdom collectively). An addition to the abstract logic supporting the general arguments of the theory is also presented. The theory has been developed concerning the role of significant transportation technology transitions as a cause of significant macroeconomic declines in nations for which the manufacture of transportation vehicles (ships, locomotives, and automobiles) is a dominant economic activity. The theory offers an explanation for periods of pronounced multiyear decline in economic growth rate--sometimes called depressions and sometimes called stagnations. One purpose of this paper is to explore whether or not Japan and Europe have each recently experienced a multiyear event of this type. In the theory and the evidence presented for it, environmental regulation of transportation vehicles has been shown to be an initiating cause of significant technical change, with sharp, sustained fuel price increases being a second frequent initiating cause. These causes of significant technical change, and their possible consequences, are potentially important considerations for those proposing policies to deal with global warming, since both fuel economy regulation and fuel price increases have been recommended by policy analysts as means to reduce transportation`s contribution to global warming. The theory has been offered and supported by publications developing mathematical models and examining US historical evidence consistent with the theory.

  15. Monday 16 June 09:30 Macroeconomics. 14:30 Advanced Econometrics 1 (2 hours).

    E-Print Network [OSTI]

    Oxford, University of

    Monday 16 June 09:30 Macroeconomics. 14:30 Advanced Econometrics 1 (2 hours). Tuesday 17 June 09 2 (2 hours). 14:30 Advanced Econometrics 2 (2 hours). Friday 20 June 09:30 Advanced Microeconomics 1

  16. Feedback and its Feedback Effect on Feedback: Photoionization Suppression and its Impact on Galactic Outflows

    E-Print Network [OSTI]

    Matthew M. Pieri; Hugo Martel

    2007-05-02T23:59:59.000Z

    We show that radiative feedback due to reionization has a pronounced effect on the extent of mechanical feedback due to galactic outflows. The photoionization of the Intergalactic Medium (IGM) suppresses low-mass galaxy formation by photoheating the gas and limiting atomic line cooling. The number of low-mass galaxies is central for the enrichment of the IGM as these objects have the capacity to enrich a significant fraction (by volume) of the Universe. We use a modified version of our galactic outflow model, combined with a simple criterion for suppression, to investigate the potential impact upon the IGM. We find that this suppression strongly reduces the enrichment of the IGM and is sensitive to the reionization history. We also investigate the contribution of halos of different masses with varying degrees of suppression.

  17. Probabilistic models for feedback systems.

    SciTech Connect (OSTI)

    Grace, Matthew D.; Boggs, Paul T.

    2011-02-01T23:59:59.000Z

    In previous work, we developed a Bayesian-based methodology to analyze the reliability of hierarchical systems. The output of the procedure is a statistical distribution of the reliability, thus allowing many questions to be answered. The principal advantage of the approach is that along with an estimate of the reliability, we also can provide statements of confidence in the results. The model is quite general in that it allows general representations of all of the distributions involved, it incorporates prior knowledge into the models, it allows errors in the 'engineered' nodes of a system to be determined by the data, and leads to the ability to determine optimal testing strategies. In this report, we provide the preliminary steps necessary to extend this approach to systems with feedback. Feedback is an essential component of 'complexity' and provides interesting challenges in modeling the time-dependent action of a feedback loop. We provide a mechanism for doing this and analyze a simple case. We then consider some extensions to more interesting examples with local control affecting the entire system. Finally, a discussion of the status of the research is also included.

  18. Feedback Processes [in Massive Star Formation]: A Theoretical Perspective

    E-Print Network [OSTI]

    Mordecai-Mark Mac Low

    2007-11-26T23:59:59.000Z

    I review the evidence for the importance of feedback from massive stars at small and large scales. The feedback mechanisms include accretion luminosity, ionizing radiation, collimated outflows, and stellar winds. The good news is that feedback doesn't entirely prevent the formation of massive stars, while the bad news is that we don't know what does limit their masses. Feedback from massive stars also influences their surroundings. I argue that this does not produce a triggering efficiency above unity, nor does it prevent lots of prompt star formation in GMCs, though it may preserve massive remnants of the clouds for many dynamical times.

  19. Negative feedback effects on star formation history and cosmic reionization

    E-Print Network [OSTI]

    Lei Wang; Jirong Mao; Shouping Xiang; Ye-Fei Yuan

    2008-12-22T23:59:59.000Z

    After considering the effects of negative feedback on the process of star formation, we explore the relationship between star formation process and the associated feedback, by investigating how the mechanical feedback from supernovae(SNe) and radiative feedback from luminous objects regulate the star formation rate and therefore affect the cosmic reionization.Based on our present knowledge of the negative feedback theory and some numerical simulations, we construct an analytic model in the framework of the Lambda cold dark matter model. In certain parameter regions, our model can explain some observational results properly. In large halos(T_vir>10000 K), both mechanical and radiative feedback have a similar behavior: the relative strength of negative feedback reduces as the redshift decreases. In contrast, in small halos (T_virfeedback gets stronger when the redshift decreases. And the star formation rate in these small halos depends very weakly on the star-formation efficiency. Our results show that the radiative feedback is important for the early generation stars. It can suppress the star formation rate considerably. But the mechanical feedback from the SNe explosions is not able to affect the early star formation significantly. The early star formation in small-halo objects is likely to be self-regulated. The radiative and mechanical feedback dominates the star formation rate of the PopII/I stars all along. The feedback from first generation stars is very strong and should not be neglected. However, their effects on the cosmic reionization are not significant, which results in a small contribution to the optical depth of Thomson scattering.

  20. Linear Quantum Feedback Networks

    E-Print Network [OSTI]

    J. Gough; R. Gohm; M. Yanagisawa

    2008-07-15T23:59:59.000Z

    The mathematical theory of quantum feedback networks has recently been developed for general open quantum dynamical systems interacting with bosonic input fields. In this article we show, for the special case of linear dynamical systems 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 the transfer functions for linear quantum systems in series, in cascade, and in feedback arrangements mediated by beam splitter devices.

  1. Track 10: Feedback and Improvement

    Broader source: Energy.gov [DOE]

    ISM Workshop Presentations Knoxville Convention Center, Knoxville, TN August 2009 Track 10: Feedback and Improvement

  2. Course title: Sustainable Development and Macroeconomics Lecturer: Dina Barbian, University of Erlangen-Nuremberg

    E-Print Network [OSTI]

    1 Course title: Sustainable Development and Macroeconomics Lecturer: Dina Barbian, University: 9-11.30 Introduction to the topic and the case studies Sustainable Development ­ Definition and History Lecture Notes Tuesday: 9-11.30 Sustainable Development and Economic Growth Searching for a new way

  3. Econometric Feedback for Runtime Risk Management in VoIP Architectures

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Econometric Feedback for Runtime Risk Management in VoIP Architectures Oussema Dabbebi, R at automatically adapting these parameters based on an econometric feedback mechanism. We mathematically describe the configuration of such risk models, by refining at runtime the model parameters based on an econometric feedback

  4. Visual Feedback in a Coordinated Hand-Eye System

    E-Print Network [OSTI]

    Woodham, Robert J.

    A system is proposed for the development of new techniques for the control and monitoring of a mechanical arm-hand. The use of visual feedback is seen to provide new interactive capabilities in a machine hand-eye system. ...

  5. Enhancement of Field Squeezing Using Coherent Feedback

    E-Print Network [OSTI]

    J. E. Gough; S. Wildfeuer

    2009-08-22T23:59:59.000Z

    The theory of quantum feedback networks has recently been developed with the aim of showing how quantum input-output components may be connected together so as to control, stabilize or enhance the performance of one of the subcomponents. In this paper we show how the degree to which an idealized component (a degenerate parametric amplifier in the strong-coupling regime) can squeeze input fields may be enhanced by placing the component in-loop in a simple feedback mechanism involving a beam splitter. We study the spectral properties of output fields, placing particular emphasis on the elastic and inelastic components of the power density.

  6. AGN feedback using AMR cosmological simulations

    E-Print Network [OSTI]

    Dubois, Yohan; Slyz, Adrianne; Teyssier, Romain

    2011-01-01T23:59:59.000Z

    Feedback processes are thought to solve some of the long-standing issues of the numerical modelling of galaxy formation: over-cooling, low angular momentum, massive blue galaxies, extra-galactic enrichment, etc. The accretion of gas onto super-massive black holes in the centre of massive galaxies can release tremendous amounts of energy to the surrounding medium. We show, with cosmological Adaptive Mesh Refinement simulations, how the growth of black holes is regulated by the feedback from Active Galactic Nuclei using a new dual jet/heating mechanism. We discuss how this large amount of feedback is able to modify the cold baryon content of galaxies, and perturb the properties of the hot plasma in their vicinity.

  7. age-dependent feedback control: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    A feedback mechanism based on hamiltonian tracking Quantum Physics (arXiv) Summary: Enviroment - caused dissipation disrupts the hamiltonian evolution of all quantum systems...

  8. The macroeconomic effects of oil price shocks : why are the 2000s so different from the 1920s?

    E-Print Network [OSTI]

    Blanchard, Olivier

    2007-01-01T23:59:59.000Z

    We characterize the macroeconomic performance of a set of industrialized economies in the aftermath of the oil price shocks of the 1970s and of the last decade, focusing on the differences across episodes. We examine four ...

  9. An Unlucky Feeling: Overconfidence and Noisy Feedback

    E-Print Network [OSTI]

    Grossman, Zachary; Owens, David

    2010-01-01T23:59:59.000Z

    way that vague or ambiguous feedback may exacerbate overcon?fact that external task-feedback situations may be much lessIncorporating Performance Feedback,” Discussion paper, work-

  10. Feedback and Interference Alignment in Networks

    E-Print Network [OSTI]

    Suh, Changho

    2011-01-01T23:59:59.000Z

    2 Feedback in the Gaussian Interference Channel 2.1Region . . . . . . . . . . . . . . . . 2.5 Feedback Capacity2.6 Role of Feedback . . . . . . . .

  11. Coherent feedback that beats all measurement-based feedback protocols

    E-Print Network [OSTI]

    Jacobs, Kurt

    We show that when the speed of control is bounded, there is a widely applicable minimal-time control problem for which a coherent feedback protocol is optimal, and is faster than all measurement-based feedback protocols, ...

  12. Educational hardware for feedback systems

    E-Print Network [OSTI]

    Dancy, Isaac

    2004-01-01T23:59:59.000Z

    This thesis explores a variety of educational feedback systems with an emphasis on developing them for in-class demonstrations and in-depth student projects. The nature of feedback systems means there is never a shortage ...

  13. Attribution Analysis of Cloud Feedback 

    E-Print Network [OSTI]

    Zhou, Chen

    2014-07-15T23:59:59.000Z

    Uncertainty on cloud feedback is the primary contributor to the large spread of equilibrium climate sensitivity (ECS) in climate models. In this study, we compare the short-term cloud feedback in climate models with observations, and evaluate...

  14. UWB communication receiver feedback loop

    DOE Patents [OSTI]

    Spiridon, Alex (Palo Alto, CA); Benzel, Dave (Livermore, CA); Dowla, Farid U. (Castro Valley, CA); Nekoogar, Faranak (San Ramon, CA); Rosenbury, Erwin T. (Castro Valley, CA)

    2007-12-04T23:59:59.000Z

    A novel technique and structure that maximizes the extraction of information from reference pulses for UWB-TR receivers is introduced. The scheme efficiently processes an incoming signal to suppress different types of UWB as well as non-UWB interference prior to signal detection. Such a method and system adds a feedback loop mechanism to enhance the signal-to-noise ratio of reference pulses in a conventional TR receiver. Moreover, sampling the second order statistical function such as, for example, the autocorrelation function (ACF) of the received signal and matching it to the ACF samples of the original pulses for each transmitted bit provides a more robust UWB communications method and system in the presence of channel distortions.

  15. Next Generation Environmentally Friendly Driving Feedback Systems...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Environmentally Friendly Driving Feedback Systems Research and Development Next Generation Environmentally Friendly Driving Feedback Systems Research and Development 2012 DOE...

  16. Regenerative feedback resonant circuit

    DOE Patents [OSTI]

    Jones, A. Mark; Kelly, James F.; McCloy, John S.; McMakin, Douglas L.

    2014-09-02T23:59:59.000Z

    A regenerative feedback resonant circuit for measuring a transient response in a loop is disclosed. The circuit includes an amplifier for generating a signal in the loop. The circuit further includes a resonator having a resonant cavity and a material located within the cavity. The signal sent into the resonator produces a resonant frequency. A variation of the resonant frequency due to perturbations in electromagnetic properties of the material is measured.

  17. Feedback from Clustered Sources During Reionization

    E-Print Network [OSTI]

    Roban Hultman Kramer; Zoltan Haiman; S. Peng Oh

    2006-04-10T23:59:59.000Z

    The reionization history of the intergalactic medium (IGM) at high redshift (z > 6) was likely strongly shaped by several global feedback processes. Because the earliest ionizing sources formed at the locations of the rare density peaks, their spatial distribution was strongly clustered. Here we demonstrate that this clustering significantly boosts the impact of feedback processes operating at high redshift. We build a semi-analytical model to include feedback and clustering simultaneously, and apply this model to the suppression of star-formation in minihalos due to photoionization. The model is built on the excursion-set-based formalism of Furlanetto, Zaldarriaga and Hernquist (2004), which incorporates the clustering of ionizing sources, and which we here extend to include suppression of star formation in minihalos. We find that clustering increases the mean HII bubble size by a factor of several, and it dramatically increases the fraction of minihalos that are suppressed, by a factor of up to 60 relative to a randomly distributed population. This enhanced suppression can significantly reduce the electron scattering optical depth, as required by the three-year data from the Wilkinson Microwave Anisotropy Probe (WMAP). We argue that source clustering is likely to similarly boost the importance of a variety of other feedback mechanisms.

  18. Feedback | DOE PAGES

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC) Environmental Assessments (EA)Budget » FYU.S. DOE Office ofPublic Access Feedback

  19. Feedback-optimized parallel tempering Monte Carlo

    E-Print Network [OSTI]

    Katzgraber, H G; Trebst, S; Huse, D A; Troyer, M

    2006-01-01T23:59:59.000Z

    brie?y discuss possible feedback schemes for systems that1742-5468/06/P03018+22$30.00 Feedback-optimized parallel5468/2006/03/P03018 Feedback-optimized parallel tempering

  20. Feedback in the Emergency Medicine Clerkships

    E-Print Network [OSTI]

    Bernard, Aaron W; Kman, Nicholas E; Khandelwal, Sorabh

    2011-01-01T23:59:59.000Z

    4. Branch WT, Paranjape A. Feedback and reflection: teachingDA, Choo EK. Providing feedback in the emergency department.26. Richardson BK. Feedback. Acad Emerg Med. 2004;11:1283e1–

  1. CRAD, Feedback and Continuous Improvement - DOE Headquarters...

    Office of Environmental Management (EM)

    CRAD, Feedback and Continuous Improvement - DOE Headquarters - December 4, 2007 CRAD, Feedback and Continuous Improvement - DOE Headquarters - December 4, 2007 December 4, 2007...

  2. Approved Module Information for BS3365, 2014/5 Module Title/Name: Macroeconomics Policy Module Code: BS3365

    E-Print Network [OSTI]

    Neirotti, Juan Pablo

    on macroeconomic policies 3 Oil and the macroeconomy ? Causes of oil price changes ? Oil prices; investment and depreciation ? Steady state ? Numerical examples 5 Economic Growth 2 ? Savings and investment Direct Investment and Policy (Professor Nigel Driffield) ? Benefits of FDI ? Aspects to FDI Policy

  3. Coherent feedback that beats all measurement-based feedback protocols

    E-Print Network [OSTI]

    Kurt Jacobs; Xiaoting Wang; Howard M. Wiseman

    2014-07-21T23:59:59.000Z

    We show that when the speed of control is bounded, there is a widely applicable minimal-time control problem for which a coherent feedback protocol is optimal, and is faster than all measurement-based feedback protocols, where the latter are defined in a strict sense. The superiority of the coherent protocol is due to the fact that it can exploit a geodesic path in Hilbert space, a path that measurement-based protocols cannot follow.

  4. University of Edinburgh Feedback Standards & Guiding Principles

    E-Print Network [OSTI]

    Edinburgh, University of

    1 University of Edinburgh Feedback Standards & Guiding Principles Feedback plays a vital role out the standards required of feedback at Edinburgh, together with a framework of guiding principles within timetabled classes (tutorials, practicals, lectures) as well as more informally. And feedback

  5. Feedback control of spin systems

    E-Print Network [OSTI]

    Claudio Altafini

    2006-01-03T23:59:59.000Z

    The feedback stabilization problem for ensembles of coupled spin 1/2 systems is discussed from a control theoretic perspective. The noninvasive nature of the bulk measurement allows for a fully unitary and deterministic closed loop. The Lyapunov-based feedback design presented does not require spins that are selectively addressable. With this method, it is possible to obtain control inputs also for difficult tasks, like suppressing undesired couplings in identical spin systems.

  6. Cosmological Galaxy Evolution with Superbubble Feedback I: Realistic Galaxies with Moderate Feedback

    E-Print Network [OSTI]

    Keller, B W; Couchman, H M P

    2015-01-01T23:59:59.000Z

    We present the first cosmological galaxy evolved using the modern smoothed particle hydrodynamics (SPH) code GASOLINE2 with superbubble feedback. We show that superbubble-driven galactic outflows powered by Type II supernovae alone can produce $\\rm{L^*}$ galaxies with flat rotation curves with circular velocities $\\sim 200\\; \\rm{km/s}$, low bulge-to-disc ratios, and stellar mass fractions that match observed values from high redshift to the present. These features are made possible by the high mass loadings generated by the evaporative growth of superbubbles. Outflows are driven extremely effectively at high redshift, expelling gas at early times and preventing overproduction of stars before $z=2$. Centrally concentrated gas in previous simulations has often lead to unrealistically high bulge to total ratios and strongly peaked rotation curves. We show that supernova-powered superbubbles alone can produce galaxies that agree well with observed properties without the need for additional feedback mechanisms or ...

  7. Oscillatory Chemical Reaction in a CSTR with Feedback Control of Flow Rate Milos Dolnik, Alexander S. Banks, and Irving R. Epstein*

    E-Print Network [OSTI]

    Epstein, Irving R.

    in a continuously stirred tank reactor (CSTR) with feedback control as a model that mimics the control mechanismOscillatory Chemical Reaction in a CSTR with Feedback Control of Flow Rate Milos Dolnik, Alexander in a single, well-stirred, flow-through reactor with feedback regulation of flow rate in three different

  8. Feedback, power control, and beamforming : methods for situational aware wireless networks

    E-Print Network [OSTI]

    Huang, Yichao

    2012-01-01T23:59:59.000Z

    Imperfect Feedback . . . . . . . . . . . . . . . . . . . .2.4.1 Imperfect Feedback Model . . . . . . . . . . .4.3 Full Feedback Analysis . . . . . . .

  9. Protoplanetary disks including radiative feedback from accreting planets

    E-Print Network [OSTI]

    Montesinos, Matias; Perez, Sebastian; Baruteau, Clement; Casassus, Simon

    2015-01-01T23:59:59.000Z

    While recent observational progress is converging on the detection of compact regions of thermal emission due to embedded protoplanets, further theoretical predictions are needed to understand the response of a protoplanetary disk to the planet formation radiative feedback. This is particularly important to make predictions for the observability of circumplanetary regions. In this work we use 2D hydrodynamical simulations to examine the evolution of a viscous protoplanetary disk in which a luminous Jupiter-mass planet is embedded. We use an energy equation which includes the radiative heating of the planet as an additional mechanism for planet formation feedback. Several models are computed for planet luminosities ranging from $10^{-5}$ to $10^{-3}$ Solar luminosities. We find that the planet radiative feedback enhances the disk's accretion rate at the planet's orbital radius, producing a hotter and more luminous environement around the planet, independently of the prescription used to model the disk's turbul...

  10. Delayed feedback control of fractional-order chaotic systems

    E-Print Network [OSTI]

    Aleksandar Gjurchinovski; Trifce Sandev; Viktor Urumov

    2011-07-06T23:59:59.000Z

    We study the possibility to stabilize unstable steady states and unstable periodic orbits in chaotic fractional-order dynamical systems by the time-delayed feedback method. By performing a linear stability analysis, we establish the parameter ranges for successful stabilization of unstable equilibria in the plane parametrizad by the feedback gain and the time delay. An insight into the control mechanism is gained by analyzing the characteristic equation of the controlled system, showing that the control scheme fails to control unstable equilibria having an odd number of positive real eigenvalues. We demonstrate that the method can also stabilize unstable periodic orbits for a suitable choice of the feedback gain, providing that the time delay is chosen to coincide with the period of the target orbit. In addition, it is shown numerically that delayed feedback control with a sinusoidally modulated time delay significantly enlarges the stability region of the steady states in comparison to the classical time-delayed feedback scheme with a constant delay.

  11. Negative feedback confers mutational robustness in yeast transcription factor regulation

    E-Print Network [OSTI]

    Denby, Charles

    2012-01-01T23:59:59.000Z

    is! possible! that! feedback! does! not! reduce! expression!positive! and! negative! feedback. ! An! alternative!reporter! to! test! for! feedback. ! The! general! approach!

  12. Carrier and Timing Synchronization of BPSK via LDPC Code Feedback

    E-Print Network [OSTI]

    Valles, Esteban

    2007-01-01T23:59:59.000Z

    using code constraint feedback,” IEEE CommunicationsQPSK using soft decision feedback,” Proc. IEEE 44th Allertonof BPSK via LDPC Code Feedback Esteban L. Vall´ s, Richard

  13. Transmit beamforming for multiple antenna systems with imperfect feedback

    E-Print Network [OSTI]

    Isukapalli, Yogananda R.

    2009-01-01T23:59:59.000Z

    2.3 A General Framework for Feedback Imperfections . . . . .FDD with Finite Rate Feedback (FDDQ) System . 2.3.3 TDDModeling of Imperfect Feedback and Error Probability

  14. Quasar Structure and Cosmological Feedback

    E-Print Network [OSTI]

    Martin Elvis

    2006-06-05T23:59:59.000Z

    Feedback from quasars and AGNs is being invoked frequently in several cosmological settings. Currently, order of magnitude, or more, uncertainties in the structure of both the wind and the 'obscuring torus' make predictions highly uncertain. To make testable models of this 'cosmological feedback' it is essential to understand the detailed structure of AGNs sufficiently well to predict their properties for the whole quasar population, at all redshifts. Progress in both areas is rapid, and I describe the near-term prospects for reducing these uncertainties for 'slow' (non-relativistic) AGN winds and the obscuring torus.

  15. Evaluation and Feedback of Medical Students Rotating in Emergency Medicine: A Model for Comprehensive Evaluation and Swift Feedback

    E-Print Network [OSTI]

    Banh, Kenny; Weichenthal, Lori; Snowden, Brandy

    2008-01-01T23:59:59.000Z

    importance of Evaluation and Feedback of Medical StudentsEvaluation and Swift Feedback Kenny Banh, MD; Loriand providing quality feedback to medical students who

  16. Material feedback in digital design tools

    E-Print Network [OSTI]

    Stanton, Christian J

    2009-01-01T23:59:59.000Z

    How do design tools feedback material behavior to the designer? Digital design tools in use by designers today provide a rich environment for design of form but offer little feedback of the material that ultimately realize ...

  17. 6.302 Feedback Systems, Fall 2002

    E-Print Network [OSTI]

    Lundberg, Kent H.

    Introduction to design of feedback systems. Properties and advantages of feedback systems. Time-domain and frequency-domain performance measures. Stability and degree of stability. Nyquist criterion. Frequency-domain design. ...

  18. MANEUVER REGULATION, TRANSVERSE FEEDBACK LINEARIZATION, AND ZERO

    E-Print Network [OSTI]

    Maggiore, Manfredi

    MANEUVER REGULATION, TRANSVERSE FEEDBACK LINEARIZATION, AND ZERO DYNAMICS Chris Nielsen,1 Manfredi focus is on output maneuver regulation where stabilizing transverse dynamics is a key requirement. Keywords: Maneuver regulation, path following, feedback linearization, zero dynamics, non-square systems

  19. LFSC - Linac Feedback Simulation Code

    SciTech Connect (OSTI)

    Ivanov, Valentin; /Fermilab

    2008-05-01T23:59:59.000Z

    The computer program LFSC (Feedback Simulation Code>) is a numerical tool for simulation beam based feedback in high performance linacs. The code LFSC is based on the earlier version developed by a collective of authors at SLAC (L.Hendrickson, R. McEwen, T. Himel, H. Shoaee, S. Shah, P. Emma, P. Schultz) during 1990-2005. That code was successively used in simulation of SLC, TESLA, CLIC and NLC projects. It can simulate as pulse-to-pulse feedback on timescale corresponding to 5-100 Hz, as slower feedbacks, operating in the 0.1-1 Hz range in the Main Linac and Beam Delivery System. The code LFSC is running under Matlab for MS Windows operating system. It contains about 30,000 lines of source code in more than 260 subroutines. The code uses the LIAR ('Linear Accelerator Research code') for particle tracking under ground motion and technical noise perturbations. It uses the Guinea Pig code to simulate the luminosity performance. A set of input files includes the lattice description (XSIF format), and plane text files with numerical parameters, wake fields, ground motion data etc. The Matlab environment provides a flexible system for graphical output.

  20. The Greenhouse Effect without Feedbacks

    E-Print Network [OSTI]

    The Greenhouse Effect without Feedbacks #12;Three Pillars Behind Climate Change! #12;1. Global. Greenhouse Gases have been on the increase. #12;3. The Greenhouse effect is a powerful theory that explains! natural greenhouse effect! · an empirical introduction #12;Moral of the story: The doubling of CO2 causes

  1. Cloud and Star Formation in Disk Galaxy Models with Feedback

    E-Print Network [OSTI]

    Rahul Shetty; Eve C. Ostriker

    2008-05-26T23:59:59.000Z

    We include feedback in global hydrodynamic simulations in order to study the star formation properties, and gas structure and dynamics, in models of galactic disks. We extend previous models by implementing feedback in gravitationally bound clouds: momentum is injected at a rate proportional to the star formation rate. This mechanical energy disperses cloud gas back into the surrounding ISM, truncating star formation in a given cloud, and raising the overall level of ambient turbulence. Propagating star formation can however occur as expanding shells collide, enhancing the density and triggering new cloud and star formation. By controlling the momentum injection per massive star and the specific star formation rate in dense gas, we find that the negative effects of high turbulence outweigh the positive ones, and in net feedback reduces the fraction of dense gas and thus the overall star formation rate. The properties of the large clouds that form are not, however, very sensitive to feedback, with cutoff masses of a few million solar masses, similar to observations. We find a relationship between the star formation rate surface density and the gas surface density with a power law index ~2 for our models with the largest dynamic range, consistent with theoretical expectations for our model of disk flaring. We point out that the value of the "Kennicutt-Schmidt" index depends on the thickness of the disk. With our simple feedback prescription (a single combined star formation event per cloud), we find that global spiral patterns are not sustained; less correlated feedback and smaller scale turbulence appear to be necessary for spiral patterns to persist.

  2. aggression control mechanisms: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    A feedback mechanism based on hamiltonian tracking Quantum Physics (arXiv) Summary: Enviroment - caused dissipation disrupts the hamiltonian evolution of all quantum systems...

  3. Develop feedback system for intelligent dynamic resource allocation to improve application performance.

    SciTech Connect (OSTI)

    Gentile, Ann C.; Brandt, James M.; Tucker, Thomas (Open Grid Computing, Inc., Austin, TX); Thompson, David

    2011-09-01T23:59:59.000Z

    This report provides documentation for the completion of the Sandia Level II milestone 'Develop feedback system for intelligent dynamic resource allocation to improve application performance'. This milestone demonstrates the use of a scalable data collection analysis and feedback system that enables insight into how an application is utilizing the hardware resources of a high performance computing (HPC) platform in a lightweight fashion. Further we demonstrate utilizing the same mechanisms used for transporting data for remote analysis and visualization to provide low latency run-time feedback to applications. The ultimate goal of this body of work is performance optimization in the face of the ever increasing size and complexity of HPC systems.

  4. Positive Feedback Regulation Results in Spatial Clustering and Fast Spreading of Active Signaling Molecules on a Cell Membrane

    E-Print Network [OSTI]

    Jayajit Das; Mehran Kardar; Arup K. Chakraborty

    2009-06-29T23:59:59.000Z

    Positive feedback regulation is ubiquitous in cell signaling networks, often leading to binary outcomes in response to graded stimuli. However, the role of such feedbacks in clustering, and in spatial spreading of activated molecules, has come to be appreciated only recently. We focus on the latter, using a simple model developed in the context of Ras activation with competing negative and positive feedback mechanisms. We find that positive feedback, in the presence of slow diffusion, results in clustering of activated molecules on the plasma membrane, and rapid spatial spreading as the front of the cluster propagates with a constant velocity (dependent on the feedback strength). The advancing fronts of the clusters of the activated species are rough, with scaling consistent with the Kardar-Parisi-Zhang (KPZ) equation in one dimension. Our minimal model is general enough to describe signal transduction in a wide variety of biological networks where activity in the membrane-proximal region is subject to feedback regulation.

  5. On-line optical flow feedback for mobile robot localization/navigation

    E-Print Network [OSTI]

    Sorensen, David Kristin

    2004-09-30T23:59:59.000Z

    ON-LINE OPTICAL FLOW FEEDBACK FOR MOBILE ROBOT LOCALIZATION/NAVIGATION A Thesis by DAVID KRISTIN SORENSEN Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE May 2003 Major Subject: Mechanical Engineering ON-LINE OPTICAL FLOW FEEDBACK FOR MOBILE ROBOT LOCALIZATION/NAVIGATION A Thesis by DAVID KRISTIN SORENSEN Submitted to Texas A&M University in partial fulfillment...

  6. Rf Feedback free electron laser

    DOE Patents [OSTI]

    Brau, Charles A. (Los Alamos, NM); Swenson, Donald A. (Los Alamos, NM); Boyd, Jr., Thomas J. (Los Alamos, NM)

    1981-01-01T23:59:59.000Z

    A free electron laser system and electron beam system for a free electron laser which use rf feedback to enhance efficiency. Rf energy is extracted from an electron beam by decelerating cavities and returned to accelerating cavities using rf returns such as rf waveguides, rf feedthroughs, etc. This rf energy is added to rf klystron energy to lower the required input energy and thereby enhance energy efficiency of the system.

  7. Feedback reduction techniques and fairness in multi-user MIMO broadcast channels with random beamforming

    E-Print Network [OSTI]

    Pugh, Matthew Owen

    2011-01-01T23:59:59.000Z

    the Feedback . . . . . . . . . . . . . . . . . 2.72.5 MMSE Receivers and Feedback . . . . . . . . . . .1.2.1 Feedback Reduction Techniques Exploiting Spa- tial

  8. Radiative feedback from ionized gas

    E-Print Network [OSTI]

    S. C. O. Glover

    2007-03-28T23:59:59.000Z

    H2 formation in metal-free gas occurs via the intermediate H- or H2+ ions. Destruction of these ions by photodissociation therefore serves to suppress H2 formation. In this paper, I highlight the fact that several processes that occur in ionized primordial gas produce photons energetic enough to photodissociate H- or H2+ and outline how to compute the photodissociation rates produced by a particular distribution of ionized gas. I also show that there are circumstances of interest, such as during the growth of HII regions around the first stars, in which this previously overlooked form of radiative feedback is of considerable importance.

  9. Feedback enhanced plasma spray tool

    DOE Patents [OSTI]

    Gevelber, Michael Alan; Wroblewski, Donald Edward; Fincke, James Russell; Swank, William David; Haggard, Delon C.; Bewley, Randy Lee

    2005-11-22T23:59:59.000Z

    An improved automatic feedback control scheme enhances plasma spraying of powdered material through reduction of process variability and providing better ability to engineer coating structure. The present inventors discovered that controlling centroid position of the spatial distribution along with other output parameters, such as particle temperature, particle velocity, and molten mass flux rate, vastly increases control over the sprayed coating structure, including vertical and horizontal cracks, voids, and porosity. It also allows improved control over graded layers or compositionally varying layers of material, reduces variations, including variation in coating thickness, and allows increasing deposition rate. Various measurement and system control schemes are provided.

  10. Integrating User Feedback Log into Relevance Feedback by Coupled SVM for Content-Based Image Retrieval

    E-Print Network [OSTI]

    Lyu, Michael R.

    , the user feedback log is one of the most important resources to bridge the seman- tic gap problem in image to re- peat many rounds of feedback in order to achieve satisfac- tory results. Hence, the learning task

  11. Feedback Induced Death in Coupled Oscillators

    E-Print Network [OSTI]

    Ming Luo

    2011-11-10T23:59:59.000Z

    We investigate oscillation death in systems of coupled nonlinear oscillators with feedback loop. We find that feedback results in oscillation death both in small sets or large ensembles. More importantly, the death zone in parameter space is significantly enlarged and oscillation death could occur even in coupled identical oscillators in the presence of feedback. We find that there are two different ways to oscillation death, namely desynchronization and completely synchronization induced oscillation death. Feedback induced oscillation death may be used to suppress unexpected oscillations, e.g., in chaotic laser arrays.

  12. Feedback Cooling of a Single Neutral Atom

    E-Print Network [OSTI]

    Markus Koch; Christian Sames; Alexander Kubanek; Matthias Apel; Maximilian Balbach; Alexei Ourjoumtsev; Pepijn W. H. Pinkse; Gerhard Rempe

    2010-10-15T23:59:59.000Z

    We demonstrate feedback cooling of the motion of a single rubidium atom trapped in a high-finesse optical resonator to a temperature of about 160 \\mu K. Time-dependent transmission and intensity-correlation measurements prove the reduction of the atomic position uncertainty. The feedback increases the 1/e storage time into the one second regime, 30 times longer than without feedback. Feedback cooling therefore rivals state-of-the-art laser cooling, but with the advantages that it requires less optical access and exhibits less optical pumping.

  13. Feedbacks Between Hydrological Heterogeneity and Bioremediation

    E-Print Network [OSTI]

    Hubbard, Susan

    Feedbacks Between Hydrological Heterogeneity and Bioremediation Induced Biogeochemical, intensively studied over the last 20 years (4), has potential to further impact bioremediation efforts

  14. Information and Feedback Institutional Change Principle | Department...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    monthly energy feedback and staff monitors to reinforce communication and activity, which led to improved routine practices and significant energy savings. Driving Operational...

  15. External optical feedback in semiconductor lasers

    E-Print Network [OSTI]

    Mebrahtu, Philemon

    1990-01-01T23:59:59.000Z

    . . . . . . . . . . . . . . . . . . . 15 17 18 18 20 10. Longitudinal mode spectra with and without mirror feedback . . . 22 11. Schematic diagram for the set up of fiber cavity feedback 12a. Picture of tapered PMSM fiber 12b. Set up used to align PMSM fiber 13. L - I plot... MIRROR FEEDBACK t I T' SOLITARY LASER DIODE 6. 25 dB/? + -50dB Fig 10. Longitudinal mode spectra with and without mirror feedback 23 B. Fiber Cavity A polarization-maintaining single-mode (PMSM) fiber 73. 8 cm long supplied by AT&T is used...

  16. II MODEL AND FEEDBACK LINEARIZING CONTROLLER 1 A Multilayer Perceptron Replaces a Feedback

    E-Print Network [OSTI]

    Amaral, José Nelson

    II MODEL AND FEEDBACK LINEARIZING CONTROLLER 1 A Multilayer Perceptron Replaces a Feedback Linearization Controller in a Nonlinear Servomechanism Jos'e F. Haffner, Ney T. Meyrer, Jos'e N. Amaral and Lu'is F. A. Pereira Abstract--- A Feedback Linearizing Controller (FLC) is used to train a multilayer

  17. Effect of downstream feedback on the achievable performance of feedback control loops for serial processes

    E-Print Network [OSTI]

    Duffy, Ken

    ]. For control design purposes, the common approach is to use linear models obtained around a certain operationEffect of downstream feedback on the achievable performance of feedback control loops for serial-- This paper deals with feedback control of serial processes, that is, processes formed by the series

  18. Detecting vegetation-precipitation feedbacks in mid-Holocene North Africa from two climate models

    SciTech Connect (OSTI)

    Wang, Yi; Notaro, Michael; Liu, Zhengyu; Gallimore, Robert; Levis, Samuel; Kutzbach, John E.

    2008-03-31T23:59:59.000Z

    Using two climate-vegetation model simulations from the Fast Ocean Atmosphere Model (FOAM) and the Community Climate System Model (CCSM, version 2), we investigate vegetation-precipitation feedbacks across North Africa during the mid-Holocene. From mid-Holocene snapshot runs of FOAM and CCSM2, we detect a negative feedback at the annual timescale with our statistical analysis. Using the Monte- Carlo bootstrap method, the annual negative feedback is further confirmed to be significant in both simulations. Additional analysis shows that this negative interaction is partially caused by the competition between evaporation and transpiration in North African grasslands. Furthermore, we find the feedbacks decrease with increasing timescales, and change signs from positive to negative at increasing timescales in FOAM. The proposed mechanism for this sign switch is associated with the different persistent timescales of upper and lower soil water contents, and their interactions with vegetation and atmospheric precipitation.

  19. RF power recovery feedback circulator

    DOE Patents [OSTI]

    Sharamentov, Sergey I. (Bolingbrook, IL)

    2011-03-29T23:59:59.000Z

    A device and method for improving the efficiency of RF systems having a Reflective Load. In the preferred embodiment, Reflected Energy from a superconducting resonator of a particle accelerator is reintroduced to the resonator after the phase of the Reflected Energy is aligned with the phase of the Supply Energy from a RF Energy Source. In one embodiment, a Circulator is used to transfer Reflected Energy from the Reflective Load into a Phase Adjuster which aligns the phase of the Reflected Energy with that of the Supply Energy. The phase-aligned energy is then combined with the Supply Energy, and reintroduced into the Reflective Load. In systems having a constant phase shift, the Phase Adjuster may be designed to shift the phase of the Reflected Energy by a constant amount using a Phase Shifter. In systems having a variety (variable) phase shifts, a Phase Shifter controlled by a phase feedback loop comprising a Phase Detector and a Feedback Controller to account for the various phase shifts is preferable.

  20. Markovian feedback to control continuous variable entanglement

    E-Print Network [OSTI]

    Stefano Mancini

    2005-04-18T23:59:59.000Z

    We present a model to realize quantum feedback control of continuous variable entanglement. It consists of two interacting bosonic modes subject to amplitude damping and achieving entangled Gaussian steady state. The possibility to greatly improve the degree of entanglement by means of Markovian (direct) feedback is then shown.

  1. Optical feedback structures and methods of making

    DOE Patents [OSTI]

    Snee, Preston T; Chan, Yin Thai; Nocera, Daniel G; Bawendi, Moungi G

    2014-11-18T23:59:59.000Z

    An optical resonator can include an optical feedback structure disposed on a substrate, and a composite including a matrix including a chromophore. The composite disposed on the substrate and in optical communication with the optical feedback structure. The chromophore can be a semiconductor nanocrystal. The resonator can provide laser emission when excited.

  2. Feedback Controller Parameterizations for Reinforcement Learning

    E-Print Network [OSTI]

    Tedrake, Russ

    , such as Model Predictive Control [7] or the Linear Quadratic Regulator (LQR). More rarely, feedback policies, with learning performed using REINFORCE. While the manipulator is modeled as an open-loop stable linear systemFeedback Controller Parameterizations for Reinforcement Learning John W. Roberts CSAIL, MIT

  3. Nonlinearity of Carbon Cycle Feedbacks KIRSTEN ZICKFELD

    E-Print Network [OSTI]

    Schmittner, Andreas

    properties and anthropogenic CO2. These findings suggest that metrics of carbon cycle feedback that pos, human activities have emitted large amounts of carbon dioxide (CO2) into the atmosphere (490 PgC fromNonlinearity of Carbon Cycle Feedbacks KIRSTEN ZICKFELD Canadian Centre for Climate Modelling

  4. Linguistic constraints on compensation for altered auditory feedback

    E-Print Network [OSTI]

    Katseff, Shira Eden

    2010-01-01T23:59:59.000Z

    Response to 30 Hz /E/ F2 feedback shift. . . . . . . . . . .Response to /2/ F2 feedback shift. The x-axis marks theschematic of the State Feedback Control (SFC) model. From

  5. Feedback communication systems : fundamental limits and control-theoretic approach

    E-Print Network [OSTI]

    Ardestanizadeh, Ehsan

    2010-01-01T23:59:59.000Z

    2.2 Point-to-Point Channels with Feedback . . 2.2.1 GaussianChapter 3 Gaussian Multiple Access Channel with Feedback 3.1Channel with Feedback . . . . . . . . . . . . .4.1

  6. The Intelligent Combination of Input Shaping and PID Feedback Control

    E-Print Network [OSTI]

    Singhose, William

    The Intelligent Combination of Input Shaping and PID Feedback Control A Dissertation Presented Combination of Input Shaping and PID Feedback Control Approved by: Dr. William Singhose, Advisor School . . . . . . . . . . . . . . . . . . . . 8 1.4 PID Feedback Control . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1.5 Comparison

  7. Employing feedback in adiabatic quantum dynamics

    E-Print Network [OSTI]

    Armen E. Allahverdyan; Guenter Mahler

    2008-04-10T23:59:59.000Z

    We study quantum adiabatic dynamics, where the slowly moving field is influenced by system's state (feedback). The information for the feedback is gained from non-disturbating measurements done on an ensemble of identical non-interacting systems. The situation without feedback is governed by the adiabatic theorem: adiabatic energy level populations stay constant, while the adiabatic eigenvectors get a specific phase contribution (Berry phase). However, under feedback the adiabatic theorem does not hold: the adiabatic populations satisfy a closed equation of motion that coincides with the replicator dynamics well-known by its applications in evolutionary game theory. The feedback generates a new gauge-invariant adiabatic phase, which is free of the constraints on the Berry phase (e.g., the new phase is non-zero even for real adiabatic eigenfunctions).

  8. Multimedia Feedback Systems for Engineering

    SciTech Connect (OSTI)

    Gladwell, S.; Gottlieb, E.J.; McDonald, M.J.; Slutter, C.L.

    1998-12-15T23:59:59.000Z

    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.

  9. Getting Useful Real-Time Feedback About Your Program | Department...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Getting Useful Real-Time Feedback About Your Program Getting Useful Real-Time Feedback About Your Program Better Buildings Webinar - May 25, 2011 20110525realtimefeedback.pdf...

  10. Contractor Rating and Feedback Systems | Department of Energy

    Energy Savers [EERE]

    Contractor Rating and Feedback Systems Contractor Rating and Feedback Systems Better Buildings Residential Workforce Business Partners Peer Exchange Call Series: Contractor Rating...

  11. Energy Department Seeks Feedback on Draft Guidance for the Hydroelectr...

    Energy Savers [EERE]

    Feedback on Draft Guidance for the Hydroelectric Production Incentive Program Energy Department Seeks Feedback on Draft Guidance for the Hydroelectric Production Incentive Program...

  12. Decoherence Control in Open Quantum System via Classical Feedback

    E-Print Network [OSTI]

    Narayan Ganesan; Tzyh Jong Tarn

    2006-11-29T23:59:59.000Z

    In this work we propose a novel strategy using techniques from systems theory to completely eliminate decoherence and also provide conditions under which it can be done so. A novel construction employing an auxiliary system, the bait, which is instrumental to decoupling the system from the environment is presented. Our approach to decoherence control in contrast to other approaches in the literature involves the bilinear input affine model of quantum control system which lends itself to various techniques from classical control theory, but with non-trivial modifications to the quantum regime. The elegance of this approach yields interesting results on open loop decouplability and Decoherence Free Subspaces(DFS). Additionally, the feedback control of decoherence may be related to disturbance decoupling for classical input affine systems, which entails careful application of the methods by avoiding all the quantum mechanical pitfalls. In the process of calculating a suitable feedback the system has to be restructured due to its tensorial nature of interaction with the environment, which is unique to quantum systems. The results are qualitatively different and superior to the ones obtained via master equations. Finally, a methodology to synthesize feedback parameters itself is given, that technology permitting, could be implemented for practical 2-qubit systems to perform decoherence free Quantum Computing.

  13. Integrin activation - the importance of a positive feedback

    E-Print Network [OSTI]

    Dagmar Iber; Iain D Campbell

    2006-03-31T23:59:59.000Z

    Integrins mediate cell adhesion and are essential receptors for the development and functioning of multicellular organisms. Integrin activation is known to require both ligand and talin binding and to correlate with cluster formation but the activation mechanism and precise roles of these processes are not yet resolved. Here mathematical modeling, with known experimental parameters, is used to show that the binding of a stabilizing factor, such as talin, is alone insufficient to enable ligand-dependent integrin activation for all observed conditions; an additional positive feedback is required.

  14. Controlling entanglement by direct quantum feedback

    E-Print Network [OSTI]

    A. R. R. Carvalho; A. J. S. Reid; J. J. Hope

    2008-07-07T23:59:59.000Z

    We discuss the generation of entanglement between electronic states of two atoms in a cavity using direct quantum feedback schemes. We compare the effects of different control Hamiltonians and detection processes in the performance of entanglement production and show that the quantum-jump-based feedback proposed by us in Phys. Rev. A {\\bf 76} 010301(R) (2007) can protect highly entangled states against decoherence. We provide analytical results that explain the robustness of jump feedback, and also analyse the perspectives of experimental implementation by scrutinising the effects of imperfections and approximations in our model.

  15. Analyzing Fuel Saving Opportunities through Driver Feedback Mechanisms

    Broader source: Energy.gov (indexed) [DOE]

    rate * 30%-60% fuel savings possible - With same vehicle and powertrain - Would require vehicletraffic flow automation to actually achieve * On today's roads only incremental...

  16. Feedback Mechanisms for Improving Probabilistic Memory Prefetching Ibrahim Hur

    E-Print Network [OSTI]

    Lin, Calvin

    Corporation The University of Texas at Austin Systems and Technology Group Department of Computer Sciences of data. Stream buffers have histori- cally been biased towards long streams, because a useless prefetch of particular stream, which allows it to stop prefetching without incurring a useless prefetch. Thus, the ASD

  17. Analyzing Fuel Saving Opportunities through Driver Feedback Mechanisms |

    Office of Environmental Management (EM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742 33 1112011AT&T, Inc.'s Reply Comments AT&T,FACT SAmes LabSystemsof Energy

  18. Using Feedback Control for a Network and CPU Resource Management Application

    E-Print Network [OSTI]

    Walpole, Jonathan

    allocated to the flow at each stage of the pipeline are regulated using a feedback mechanism, based on local. Multimedia and sensor-based real-time applications use a pipeline abstraction and stream information in real and other resources at each pipeline stage. (Figure 1) Figure 1. Pipeline configuration The resources

  19. Feedback Capacity of the Compound Channel

    E-Print Network [OSTI]

    Shrader, Brooke E.

    In this work, we find the capacity of a compound finite-state channel (FSC) with time-invariant deterministic feedback. We consider the use of fixed length block codes over the compound channel. Our achievability result ...

  20. Cirrus feedback on interannual climate fluctuations

    SciTech Connect (OSTI)

    Zhou, C. [Lawrence Livermore National Laboratory, Livermore, CA (United States). Program for Climate Model Diagnosis and Intercomparison; Dessler, A. E. [Texas A& M Univ., College Station TX (United States). Department of Atmospheric Sciences; Zelinka, M. D. [Lawrence Livermore National Laboratory, Livermore, CA (United States). Program for Climate Model Diagnosis and Intercomparison; Yang, P. [Texas A& M Univ., College Station TX (United States). Department of Atmospheric Sciences; Wang, T. [Jet Propulsion Lab./Caltech, Pasadena, CA (United States)] (ORCID:0000000334308508)

    2014-12-28T23:59:59.000Z

    Cirrus clouds are not only important in determining the current climate, but also play an important role in climate change and variability. Analysis of satellite observations shows that the amount and altitude of cirrus clouds (optical depth <3.6, cloud top pressure <440 hPa) increase in response to inter-annual surface warming. Thus, cirrus clouds are likely to act as a positive feedback on short-term climate fluctuations, by reducing the planet’s ability to radiate longwave radiation to space in response to planetary surface warming. Using cirrus cloud radiative kernels, the magnitude of cirrus feedback is estimated to be 0.20±0.21W/m2/°C, which is comparable to the surface albedo feedback. Most of the cirrus feedback comes from increasing cloud amount in the tropical tropopause layer (TTL) and subtropical upper troposphere.

  1. Feedback controller parameterizations for reinforcement learning

    E-Print Network [OSTI]

    Roberts, John William

    Reinforcement Learning offers a very general framework for learning controllers, but its effectiveness is closely tied to the controller parameterization used. Especially when learning feedback controllers for weakly stable ...

  2. POLE PLACEMENT BY STATIC OUTPUT FEEDBACK FOR ...

    E-Print Network [OSTI]

    SIAM (#1) 1035 2001 Apr 10 12:32:38

    2002-06-04T23:59:59.000Z

    topology) subset U of such systems, where the real pole placement map is not surjective. It follows that, for ... Key words. linear systems, static output control feedback, pole placement. AMS subject .... is an integral power of 2. In the opposite ...

  3. Feedback-controlled adiabatic quantum computation

    E-Print Network [OSTI]

    R. D. Wilson; A. M. Zagoskin; S. Savel'ev; M. J. Everitt; Franco Nori

    2013-01-03T23:59:59.000Z

    We propose a simple feedback-control scheme for adiabatic quantum computation with superconducting flux qubits. The proposed method makes use of existing on-chip hardware to monitor the ground-state curvature, which is then used to control the computation speed to maximize the success probability. We show that this scheme can provide a polynomial speed-up in performance and that it is possible to choose a suitable set of feedback-control parameters for an arbitrary problem Hamiltonian.

  4. Coherent control and feedback cooling in a remotely-coupled hybrid atom-optomechanical system

    E-Print Network [OSTI]

    James S. Bennett; Lars S. Madsen; Mark Baker; Halina Rubinsztein-Dunlop; Warwick P Bowen

    2014-06-30T23:59:59.000Z

    Cooling to the motional ground state is an important first step in the preparation of nonclassical states of mesoscopic mechanical oscillators. Light-mediated coupling to a remote atomic ensemble has been proposed as a method to reach the ground state for low frequency oscillators. The ground state can also be reached using optical measurement followed by feedback control. Here we investigate the possibility of enhanced cooling by combining these two approaches. The combination, in general, outperforms either individual technique, though atomic ensemble-based cooling and feedback cooling each individually dominate over large regions of parameter space.

  5. Feedback stabilization of resistive shell modes in a reversed field pinch

    SciTech Connect (OSTI)

    Fitzpatrick, R.; Yu, E.P. [Institute for Fusion Studies, Department of Physics, University of Texas at Austin, Austin, Texas 78712-1060 (United States)] [Institute for Fusion Studies, Department of Physics, University of Texas at Austin, Austin, Texas 78712-1060 (United States)

    1999-09-01T23:59:59.000Z

    A reactor relevant reversed field pinch (RFP) must be capable of operating successfully when surrounded by a close-fitting resistive shell whose L/R time is much {ital shorter} than the pulse length. Resonant modes are largely unaffected by the shell resistivity, provided that the plasma rotation is maintained against the breaking effect of nonaxisymmetric eddy currents induced in the shell. This may require an auxiliary momentum source, such as a neutral beam injector. Nonresonant modes are largely unaffected by plasma rotation, and are expected to manifest themselves as nonrotating {ital resistive shell modes} growing on the L/R time of the shell. A general RFP equilibrium is subject to many simultaneously unstable resistive shell modes; the only viable control mechanism for such modes in a RFP reactor is {ital active feedback}. It is demonstrated than an {ital N}-fold toroidally symmetric arrangement of feedback coils, combined with a strictly linear feedback algorithm, is capable of {ital simultaneously stabilizing} all intrinsically unstable resistive shell modes over a wide range of different RFP equilibria. The number of coils in the toroidal direction {ital N}, at any given poloidal angle, must be greater than, or equal to, the range of toroidal mode numbers of the unstable resistive shell modes. However, this range is largely determined by the aspect-ratio of the device. The optimum coil configuration corresponds to one in which each feedback coil slightly overlaps its immediate neighbors in the toroidal direction. The critical current which must be driven around each feedback coils is, at most, a few percent of the equilibrium toroidal plasma current. The feedback scheme is robust to small deviations from pure {ital N}-fold toroidal symmetry or a pure linear response of the feedback circuits. {copyright} {ital 1999 American Institute of Physics.}

  6. ACTIVE GALACTIC NUCLEUS FEEDBACK WORKS BOTH WAYS

    SciTech Connect (OSTI)

    Zinn, P.-C.; Middelberg, E.; Dettmar, R.-J. [Astronomical Institute of Ruhr-University Bochum, Universitaetsstrasse 150, D-44801 Bochum (Germany); Norris, R. P. [CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia)

    2013-09-01T23:59:59.000Z

    Simulations of galaxy growth need to invoke strong negative feedback from active galactic nuclei (AGNs) to suppress the formation of stars and thus prevent the over-production of very massive systems. While some observations provide evidence for such negative feedback, other studies find either no feedback or even positive feedback, with increased star formation associated with higher AGN luminosities. Here we report an analysis of several hundred AGNs and their host galaxies in the Chandra Deep Field South using X-ray and radio data for sample selection. Combined with archival far-infrared data as a reliable tracer of star formation activity in the AGN host galaxies, we find that AGNs with pronounced radio jets exhibit a much higher star formation rate (SFR) than the purely X-ray-selected ones, even at the same X-ray luminosities. This difference implies that positive AGN feedback plays an important role, too, and therefore has to be accounted for in all future simulation work. We interpret this to indicate that the enhanced SFR of radio-selected AGNs arises because of jet-induced star formation, as is suggested by the different jet powers among our AGN samples, while the suppressed SFR of X-ray selected AGN is caused by heating and photo-dissociation of molecular gas by the hot AGN accretion disk.

  7. Implementing Feedback in Simulations of Galaxy Formation: A Survey of Methods

    E-Print Network [OSTI]

    R. J. Thacker; H. M. P. Couchman

    2000-01-15T23:59:59.000Z

    We present a detailed investigation of different approaches to modeling feedback in simulations of galaxy formation. Gas-dynamic forces are evaluated using Smoothed Particle Hydrodynamics (SPH) while star formation and supernova feedback are included using a three parameter model which determines the star formation rate normalization, feedback energy and lifetime of feedback regions. The star formation rate is calculated using a Lagrangian Schmidt Law for all gas particles which satisfy temperature, density and convergent flow criteria. Feedback is incorporated as thermal heating of the ISM. We compare the effects of distributing this energy over the smoothing scale or depositing it on a single particle. Radiative losses are prevented from heated particles by adjusting the density used in radiative cooling. We test the models on the formation of galaxies from cosmological initial conditions and also on isolated Milky Way and dwarf galaxies. Extremely violent feedback is necessary to produce a gas disk with angular momentum remotely close to that of observed disk galaxies. This is a result of the extreme central concentration of the dark halos in the sCDM model, and the pervasiveness of the core-halo angular momentum transport mechanism. We emphasize that the disks formed in hierarchical simulations are partially a numerical artifact produced by the minimum mass scale of the simulation acting as a highly efficient `support' mechanism. Disk formation is strongly affected by the treatment of dense regions in SPH, which along with the difficulty of representing the hierarchical formation process, means that realistic simulations of galaxy formation require far higher resolution than currently used.

  8. Stellar Feedback in Dwarf Galaxy Formation

    E-Print Network [OSTI]

    Sergey Mashchenko; James Wadsley; H. M. P. Couchman

    2007-11-29T23:59:59.000Z

    Dwarf galaxies pose significant challenges for cosmological models. In particular, current models predict a dark matter density that is divergent at the center, in sharp contrast with observations which indicate an approximately constant central density core. Energy feedback, from supernova explosions and stellar winds, has been proposed as a major factor shaping the evolution of dwarf galaxies. We present detailed cosmological simulations with sufficient resolution both to model the relevant physical processes and to directly assess the impact of stellar feedback on observable properties of dwarf galaxies. We show that feedback drives large-scale, bulk motion of the interstellar gas resulting in significant gravitational potential fluctuations and a consequent reduction in the central matter density, bringing the theoretical predictions in agreement with observations.

  9. Reconsidering Rapid Qubit Purification by Feedback

    E-Print Network [OSTI]

    H. M. Wiseman; J. F. Ralph

    2006-05-13T23:59:59.000Z

    This paper reconsiders the claimed rapidity of a scheme for the purification of the quantum state of a qubit, proposed recently in Jacobs 2003 Phys. Rev. A67 030301(R). The qubit starts in a completely mixed state, and information is obtained by a continuous measurement. Jacobs' rapid purification protocol uses Hamiltonian feedback control to maximise the average purity of the qubit for a given time, with a factor of two increase in the purification rate over the no-feedback protocol. However, by re-examining the latter approach, we show that it mininises the average time taken for a qubit to reach a given purity. In fact, the average time taken for the no-feedback protocol beats that for Jacobs' protocol by a factor of two. We discuss how this is compatible with Jacobs' result, and the usefulness of the different approaches.

  10. Time-delayed quantum feedback control

    E-Print Network [OSTI]

    Arne L. Grimsmo

    2015-02-24T23:59:59.000Z

    A theory of time-delayed coherent quantum feedback is developed. More specifically, we consider a quantum system coupled to a bosonic reservoir creating a unidirectional feedback loop. It is shown that the dynamics can be mapped onto a fictitious quantum cascade, where the system is driven by past versions of itself. The derivation of this model relies on a tensor network representation of the system-reservoir time-propagator. For concreteness, this general theory is applied to a driven two-level atom scattering into a coherent feedback loop. We demonstrate how delay effects can qualitatively change the dynamics of the atom, and how quantum control can be implemented in the presence of time-delays. A realization with a superconducting qubit serving as an artificial atom is discussed.

  11. Feedback improves the generalized degrees of freedom of the strong interference channel

    E-Print Network [OSTI]

    Cadambe, Viveck R; Jafar, Syed A

    2008-01-01T23:59:59.000Z

    the mimo interference channel with feedback,” 2008. Preprintthe impact of relays, feedback, co- operation and full-Feedback improves the generalized degrees of freedom of the

  12. Physical process Mechanical mechanisms

    E-Print Network [OSTI]

    Berlin,Technische Universität

    1 Physical process Generation · Mechanical mechanisms F = m·a · Electric/Magnetic mechanisms F = B·i·l · Fluid dynamic/Hydraulic mechanisms q, p, ij · Thermal/Optical #12;2 Source unit

  13. Stabilizing feedback controls for quantum systems

    E-Print Network [OSTI]

    Mazyar Mirrahimi; Ramon van Handel

    2005-11-10T23:59:59.000Z

    No quantum measurement can give full information on the state of a quantum system; hence any quantum feedback control problem is neccessarily one with partial observations, and can generally be converted into a completely observed control problem for an appropriate quantum filter as in classical stochastic control theory. Here we study the properties of controlled quantum filtering equations as classical stochastic differential equations. We then develop methods, using a combination of geometric control and classical probabilistic techniques, for global feedback stabilization of a class of quantum filters around a particular eigenstate of the measurement operator.

  14. Efficient Quantum Filtering for Quantum Feedback Control

    E-Print Network [OSTI]

    Pierre Rouchon; Jason F. Ralph

    2015-01-06T23:59:59.000Z

    We discuss an efficient numerical scheme for the recursive filtering of diffusive quantum stochastic master equations. We show that the resultant quantum trajectory is robust and may be used for feedback based on inefficient measurements. The proposed numerical scheme is amenable to approximation, which can be used to further reduce the computational burden associated with calculating quantum trajectories and may allow real-time quantum filtering. We provide a two-qubit example where feedback control of entanglement may be within the scope of current experimental systems.

  15. ALSHub: Submit Proposals and Give Us Your Feedback!

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ALSHub: Submit Proposals and Give Us Your Feedback ALSHub: Submit Proposals and Give Us Your Feedback Print The ALS User Office rolled out ALSHub, a new user portal, five months...

  16. Transmit beamforming for multiple antenna systems with imperfect feedback

    E-Print Network [OSTI]

    Isukapalli, Yogananda R.

    2009-01-01T23:59:59.000Z

    a transmit beamforming MISO system with imperfect feedback.error proba- bility of a MISO transmit beamforming system,”of finite rate feedback MISO systems in the presence of es-

  17. Feedback control of flow separation using synthetic jets

    E-Print Network [OSTI]

    Kim, Kihwan

    2006-04-12T23:59:59.000Z

    The primary goal of this research is to assess the effect of synthetic jets on flow separation and provide a feedback control strategy for flow separation using synthetic jets. The feedback control synthesis is conducted based upon CFD simulation...

  18. Detectable Signatures of Cosmic Radiative Feedback

    E-Print Network [OSTI]

    R. Schneider; R. Salvaterra; T. Roy Choudhury; A. Ferrara; C. Burigana; L. A. Popa

    2007-12-04T23:59:59.000Z

    We use a semi-analytical model to study the impact of reionization, and the associated radiative feedback, on galaxy formation. Two feedback models have been considered: (i) a standard prescription, according to which star formation is totally suppressed in galaxies with circular velocity below a critical threshold (model CF06) and (ii) a characterization based on the filtering scale (model G00), allowing for a gradual reduction of the gas available for star formation in low-mass galaxies. In model CF06 reionization starts at z ~ 15-20, is 85% complete by z ~ 10; at the same z, the ionized fraction is 16% in model G00. The models match SDSS constraints on the evolution of the neutral hydrogen fraction at z feedback models. Deviations among radiative feedback prescriptions emerge when considering the expected HI 21 cm background signal, where a ~ 15 mK absorption feature in the range 75-100 MHz is present in model G00 and a global shift of the emission feature preceding reionization towards larger frequencies occurs in the same model. Single dish observations with existing or forthcoming low-frequency radio telescopes can achieve mK sensitivity, allowing the identification of these features provided that foregrounds can be accurately subtracted.

  19. Opportunity for feedback Opportunity for updates

    E-Print Network [OSTI]

    Opportunity for feedback Opportunity for updates Opportunity to find out all of the things I don) What do these all mean? Vision (1) Values (5-10) Strategic Priorities (5-7) Education, scholarship update Research Plan Pinnacles or not? Focus on impact Update every 3 yrs Capital Plan Existing

  20. Lyapunov Functions and Feedback in Nonlinear Control

    E-Print Network [OSTI]

    Maume-Deschamps, Véronique

    Lyapunov Functions and Feedback in Nonlinear Control Francis Clarke Professeur `a l@igd.univ-lyon1.fr Summary. The method of Lyapunov functions plays a central role in the study to consider nonsmooth Lyapunov functions, even if the underlying control dynamics are themselves smooth. We

  1. Combining Channel Output Feedback and CSI Feedback for MIMO Wireless Systems

    E-Print Network [OSTI]

    Agrawal, Mayur; Balakrishnan, Venkataramanan

    2010-01-01T23:59:59.000Z

    The use of channel output feedback to improve the reliability of fading channels has received scant attention in the literature. In most work on feedback for fading channels, only channel state information (CSI) feedback has been exploited for coding at the transmitter. In this work, the design of a coding scheme for multiple-input multiple-output (MIMO) fading systems with channel output and channel state feedback at the transmitter is considered. Under the assumption of additive white Gaussian noise and an independent and identically distributed fading process, a simple linear coding strategy that achieves any rate up to capacity is proposed. The framework assumes perfect CSI at the transmitter and receiver. This simple linear processing scheme can provide a doubly exponential probability of error decay with blocklength for all rates less than capacity. Remarkably, this encoding scheme actually consists of two separate encoding blocks: one that adapts to the current CSI and one that adapts to the previous c...

  2. Investigating a model of optimised AGN feedback

    E-Print Network [OSTI]

    Edward C. D. Pope

    2011-03-02T23:59:59.000Z

    Feedback heating from AGN in massive galaxies and galaxy clusters can be thought of as a naturally occurring control system which plays a significant role in regulating both star formation rates and the X-ray luminosity of the surrounding hot gas. In the simplest case, negative feedback can be viewed as a system response that is `optimised' to minimise deviations from equilibrium, such that the system rapidly evolves towards a steady state. However, a general solution of this form appears to be incompatible with radio observations which indicate intermittent AGN outbursts. Here, we explore an energetically favourable scenario in which feedback is required to both balance X-ray gas cooling, and minimise the sum of the energy radiated by the gas and the energy injected by the AGN. This specification is equivalent to ensuring that AGN heating balances the X-ray gas cooling with minimum black hole growth. It is shown that minimum energy heating occurs in discrete events, and not at a continuous, constant level. Furthermore, systems with stronger feedback experience proportionally more powerful heating events, but correspondingly smaller duty cycles. Interpreting observations from this perspective would imply that stronger feedback occurs in less massive objects - elliptical galaxies, rather than galaxy clusters. One direct consequence of this effect would be that AGN heating events are sufficiently powerful to expel hot gas from the gravitational potential of a galaxy, but not a galaxy cluster, which is consistent with theoretical explanations for the steepening of the L_X-T relation at temperatures below 1-2 keV.

  3. Real-time calibration of a feedback trap

    SciTech Connect (OSTI)

    Gavrilov, Mom?ilo; Jun, Yonggun; Bechhoefer, John, E-mail: johnb@sfu.ca [Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6 (Canada)

    2014-09-15T23:59:59.000Z

    Feedback traps use closed-loop control to trap or manipulate small particles and molecules in solution. They have been applied to the measurement of physical and chemical properties of particles and to explore fundamental questions in the non-equilibrium statistical mechanics of small systems. These applications have been hampered by drifts in the electric forces used to manipulate the particles. Although the drifts are small for measurements on the order of seconds, they dominate on time scales of minutes or slower. Here, we show that a recursive maximum likelihood (RML) algorithm can allow real-time measurement and control of electric and stochastic forces over time scales of hours. Simulations show that the RML algorithm recovers known parameters accurately. Experimental estimates of diffusion coefficients are also consistent with expected physical properties.

  4. Transverse Feedback in a 100 TeV Storage Ring

    E-Print Network [OSTI]

    Lambertson, G.

    2011-01-01T23:59:59.000Z

    Proceedings Transverse Feedback in a 100 TeV Storage Ring G.DE93 001571 TRANSVERSE FEEDBACK IN A 100 TeV STORAGE RING*IS UNLIMITED r-t_9. TRANSVERSE FEEDBACK IN A 100 TeV STORAGE

  5. Optimizing Feedback in Energy Harvesting MISO Communication Channels

    E-Print Network [OSTI]

    Gesbert, David

    Optimizing Feedback in Energy Harvesting MISO Communication Channels Rajeev Gangula1 , David.gunduz@imperial.ac.uk Abstract--In this work,1 we consider the optimization of feedback in a point-to-point MISO channel in the context of a simple multiple antenna system, namely MISO channel, where feedback can be used to improve

  6. Multimodal feedback for the acquisition of small targets

    E-Print Network [OSTI]

    Williamson, John

    -haptic `sticky' feedback. The tactile conditions used stimulation through vibration (rather than force- feedback the need for caution, revealing that excessive feedback can damage interaction though `noise such as vibration on a train or plane, when bright light reduces screen clarity or when using a laptop trackpoint

  7. SURVEY LEADERSHIP The Manager's Guide to Survey Feedback & Action Planning

    E-Print Network [OSTI]

    Squire, Larry R.

    SURVEY LEADERSHIP The Manager's Guide to Survey Feedback & Action Planning A guide designed to help is subject to change without notice. #12;Morehead Associates Page 2 of 115 Manager's Guide to Survey Feedback;Morehead Associates Page 3 of 115 Manager's Guide to Survey Feedback and Action Planning Action Planning

  8. Power Management Mechanism Exploiting Network and Video Information over Wireless

    E-Print Network [OSTI]

    Bouras, Christos

    Power Management Mechanism Exploiting Network and Video Information over Wireless Links Christos information from higher network layers may be utilized for more efficient power management in wireless- tune transmission power according to information received from the transport (feedback reports from

  9. Power Management Mechanism Exploiting Network and Video Information over Wireless

    E-Print Network [OSTI]

    Bouras, Christos

    Power Management Mechanism Exploiting Network and Video Information over Wireless Links Christos- layer information from higher network layers may be utilized for more efficient power management that fine- tune transmission power according to information received from the transport (feedback reports

  10. Residential Feedback Devices and Programs: Opportunities for Natural Gas

    SciTech Connect (OSTI)

    Kerr, R.; Tondro, M.

    2012-12-01T23:59:59.000Z

    Behavior-based approaches have been a growing interest in the energy efficiency field over recent years and the use of residential energy feedback has garnered particular interest. By providing an increased level of detail, feedback can greatly increase a consumer's understanding of how energy is used in their home. This project reviewed the existing body of research on electricity feedback to identify parallel lessons for gas, discussed the benefits and challenges of different types of feedback, and identifying three feedback options that show strong potential for natural gas savings.

  11. Galaxy formation with radiative and chemical feedback

    E-Print Network [OSTI]

    Graziani, L; Schneider, R; Kawata, D; de Bennassuti, M; Maselli, A

    2015-01-01T23:59:59.000Z

    Here we introduce GAMESH, a novel pipeline which implements self-consistent radiative and chemical feedback in a computational model of galaxy formation. By combining the cosmological chemical-evolution model GAMETE with the radiative transfer code CRASH, GAMESH can post process realistic outputs of a N-body simulation describing the redshift evolution of the forming galaxy. After introducing the GAMESH implementation and its features, we apply the code to a low-resolution N-body simulation of the Milky Way formation and we investigate the combined effects of self-consistent radiative and chemical feedback. Many physical properties, which can be directly compared with observations in the Galaxy and its surrounding satellites, are predicted by the code along the merger-tree assembly. The resulting redshift evolution of the Local Group star formation rates, reionisation and metal enrichment along with the predicted Metallicity Distribution Function of halo stars are critically compared with observations. We dis...

  12. IEEE TRANSACTIONS ON AUTOMATIC CONTROL, VOL. 48, NO. 8, AUGUST 2003 1439 From Nonlinear to Hamiltonian via Feedback

    E-Print Network [OSTI]

    Pappas, George J.

    IEEE TRANSACTIONS ON AUTOMATIC CONTROL, VOL. 48, NO. 8, AUGUST 2003 1439 From Nonlinear to Hamiltonian via Feedback Paulo Tabuada and George J. Pappas Abstract--Mechanical control systems are an especially interesting and important class of nonlinear control systems. They posses a rich mathe- matical

  13. Quantum feedback control and classical control theory

    SciTech Connect (OSTI)

    Doherty, Andrew C. [Department of Physics, University of Auckland, Private Bag 92019, Auckland, (New Zealand)] [Department of Physics, University of Auckland, Private Bag 92019, Auckland, (New Zealand); Habib, Salman [Theoretical Division, T-8, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Theoretical Division, T-8, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Jacobs, Kurt [Theoretical Division, T-8, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Theoretical Division, T-8, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Mabuchi, Hideo [Norman Bridge Laboratory of Physics 12-33, California Institute of Technology, Pasadena, California 91125 (United States)] [Norman Bridge Laboratory of Physics 12-33, California Institute of Technology, Pasadena, California 91125 (United States); Tan, Sze M. [Department of Physics, University of Auckland, Private Bag 92019, Auckland, (New Zealand)] [Department of Physics, University of Auckland, Private Bag 92019, Auckland, (New Zealand)

    2000-07-01T23:59:59.000Z

    We introduce and discuss the problem of quantum feedback control in the context of established formulations of classical control theory, examining conceptual analogies and essential differences. We describe the application of state-observer-based control laws, familiar in classical control theory, to quantum systems and apply our methods to the particular case of switching the state of a particle in a double-well potential. (c) 2000 The American Physical Society.

  14. Physical regimes for feedback in galaxy formation

    E-Print Network [OSTI]

    P. Monaco

    2004-04-13T23:59:59.000Z

    We present a new (semi-)analytic model for feedback in galaxy formation. The ISM is modeled as a two-phase medium in pressure equilibrium. The remnants of exploding type II SNe percolate into super-bubbles (SBs) that sweep the ISM, heating the hot phase (if the SB is adiabatic) or cooling it (in the snowplow stage, when the interior gas of the SB has cooled). The resulting feedback regimes occur in well-defined regions of the space defined by vertical scale-length and surface density of the structure. When SBs blow out in the adiabatic regime, the efficiency of SNe in heating the ISM is ~5 per cent, with \\~80 per cent of the energy budget injected into the external halo, and the outcoming ISM is self-regulated to a state similar to that found in the Milky Way. Feedback is most efficient when SBs are pressure-confined in the adiabatic regime. In some significant regions of the parameter space confinement takes place in the snowplow stage; then the hot phase has a lower temperature and star formation is quicker. In some critical cases, the hot phase is strongly depleted and the cold phase percolates the whole volume, giving rise to a sudden burst of star formation. Strong galactic winds are predicted to happen only in critical cases. This model provides a starting point for constructing a realistic grid of feedback solutions to be used in galaxy formation codes. The predictive power of this model extends to many properties of the ISM, so that most parameters can be constrained by reproducing the main properties of the Milky Way. (Abridged)

  15. Cool core cycles: Cold gas and AGN jet feedback in cluster cores

    E-Print Network [OSTI]

    Prasad, Deovrat; Babul, Arif

    2015-01-01T23:59:59.000Z

    Using high-resolution 3-D and 2-D (axisymmetric) hydrodynamic simulations in spherical geometry, we study the evolution of cool cluster cores heated by feedback-driven bipolar active galactic nuclei (AGN) jets. Condensation of cold gas, and the consequent enhanced accretion, is required for AGN feedback to balance radiative cooling with reasonable efficiencies, and to match the observed cool core properties. A feedback efficiency (mechanical luminosity $\\approx \\epsilon \\dot{M}_{\\rm acc} c^2$; where $\\dot{M}_{\\rm acc}$ is the mass accretion rate at 1 kpc) as small as $5 \\times 10^{-5}$ is sufficient to reduce the cooling/accretion rate by $\\sim 10$ compared to a pure cooling flow. This value is smaller compared to the ones considered earlier, and is consistent with the jet efficiency and the fact that only a small fraction of gas at 1 kpc is accreted on to the supermassive black hole (SMBH). We find hysteresis cycles in all our simulations with cold mode feedback: {\\em condensation} of cold gas when the ratio...

  16. The Local Group as an Astrophysical Laboratory for Massive Star Feedback

    E-Print Network [OSTI]

    M. S. Oey

    2003-07-07T23:59:59.000Z

    The feedback effects of massive stars on their galactic and intergalactic environments can dominate evolutionary processes in galaxies and affect cosmic structure in the Universe. Only the Local Group offers the spatial resolution to quantitatively study feedback processes on a variety of scales. Lyman continuum radiation from hot, luminous stars ionizes HII regions and is believed to dominate production of the warm component of the interstellar medium (ISM). Some of this radiation apparently escapes from galaxies into the intergalactic environment. Supernovae and strong stellar winds generate shell structures such as supernova remnants, stellar wind bubbles, and superbubbles around OB associations. Hot (10^6 K) gas is generated within these shells, and is believed to be the origin of the hot component of the ISM. Superbubble activity thus is likely to dominate the ISM structure, kinematics, and phase balance in star-forming galaxies. Galactic superwinds in starburst galaxies enable the escape of mass, ionizing radiation, and heavy elements. Although many important issues remain to be resolved, there is little doubt that feedback processes plays a fundamental role in energy cycles on scales ranging from individual stars to cosmic structure. This contribution reviews studies of radiative and mechanical feedback in the Local Group.

  17. Simulating galactic outflows with kinetic supernova feedback

    E-Print Network [OSTI]

    Claudio Dalla Vecchia; Joop Schaye

    2008-05-07T23:59:59.000Z

    Feedback from star formation is thought to play a key role in the formation and evolution of galaxies, but its implementation in cosmological simulations is currently hampered by a lack of numerical resolution. We present and test a sub-grid recipe to model feedback from massive stars in cosmological smoothed particle hydrodynamics simulations. The energy is distributed in kinetic form among the gas particles surrounding recently formed stars. The impact of the feedback is studied using a suite of high-resolution simulations of isolated disc galaxies embedded in dark halos with total mass 10^{10} and 10^{12} Msol/h. We focus in particular on the effect of pressure forces on wind particles within the disc, which we turn off temporarily in some of our runs to mimic a recipe that has been widely used in the literature. We find that this popular recipe gives dramatically different results because (ram) pressure forces on expanding superbubbles determine both the structure of the disc and the development of large-scale outflows. Pressure forces exerted by expanding superbubbles puff up the disc, giving the dwarf galaxy an irregular morphology and creating a galactic fountain in the massive galaxy. Hydrodynamic drag within the disc results in a strong increase of the effective mass loading of the wind for the dwarf galaxy, but quenches much of the outflow in the case of the high-mass galaxy.

  18. Massive stars: Feedback effects in the local universe

    E-Print Network [OSTI]

    M. S. Oey; C. J. Clarke

    2007-03-02T23:59:59.000Z

    We examine self-consistent parameterizations of the high-mass stellar population and resulting feedback, including mechanical, radiative, and chemical feedback, as we understand them locally. To date, it appears that the massive star population follows simple power-law clustering that extends down to individual field OB stars, and the robust stellar IMF seems to have a constant upper-mass limit. These properties result in specific patterns in the HII region LF and ionization of the diffuse, warm ionized medium. The resulting SNe generate superbubbles whose size distribution is also described by a simple power law, and from which a galaxy's porosity parameter is easily derived. A critical star-formation threshold can then be estimated, above which the escape of Lyman continuum photons, hot gas, and nucleosynthetic products is predicted. A first comparison with a large H-alpha sample of galaxies is broadly consistent with this prediction, and suggests that ionizing photons likely escapes from starburst galaxies. The superbubble size distribution also offers a basis for a Simple Inhomogeneous Model for galactic chemical evolution, which is especially relevant to metal-poor systems and instantaneous metallicity distributions. This model offers an alternative interpretation of the Galactic halo metallicity distribution and emphasizes the relative importance of star-formation intensity, in addition to age, in a system's evolution. The fraction of zero-metallicity, Population III stars is easily predicted for any such model. We emphasize that all these phenomena can be modeled in a simple, analytic framework over an extreme range in scale, offering powerful tools for understanding the role of massive stars in the cosmos. (Abridged)

  19. 10/24/14, 1:40 PMA New Macroeconomic Strategy by Jeffrey D. Sachs -Project Syndicate Page 1 of 4http://www.project-syndicate.org/print/declining-investment-in-rich-countries-by-jeffrey-d-sachs-2014-10

    E-Print Network [OSTI]

    books include The End of Poverty and Common Wealth. OCT 23, 2014 A New Macroeconomic Strategy NEW YORK of income that is saved rather than consumed should be invested to improve future wellbeing that we turn "excess" saving into another consumption binge. Supply-siders, by contrast, want to promote

  20. Systematic errors in the measurement of neutrino masses due to baryonic feedback processes: Prospects for stage IV lensing surveys

    E-Print Network [OSTI]

    Aravind Natarajan; Andrew R. Zentner; Nicholas Battaglia; Hy Trac

    2014-09-04T23:59:59.000Z

    We examine the importance of baryonic feedback effects on the matter power spectrum on small scales, and the implications for the precise measurement of neutrino masses through gravitational weak lensing. Planned large galaxy surveys such as the Large Synoptic Sky Telescope (LSST) and Euclid are expected to measure the sum of neutrino masses to extremely high precision, sufficient to detect non-zero neutrino masses even in the minimal mass normal hierarchy. We show that weak lensing of galaxies while being a very good probe of neutrino masses, is extremely sensitive to baryonic feedback processes. We use publicly available results from the Overwhelmingly Large Simulations (OWLS) project to investigate the effects of active galactic nuclei feedback, the nature of the stellar initial mass function, and gas cooling rates, on the measured weak lensing shear power spectrum. Using the Fisher matrix formalism and priors from CMB+BAO data, we show that when one does not account for feedback, the measured neutrino mass may be substantially larger or smaller than the true mass, depending on the dominant feedback mechanism, with the mass error |\\Delta m_nu| often exceeding the mass m_nu itself. We also consider gravitational lensing of the cosmic microwave background (CMB) and show that it is not sensitive to baryonic feedback on scales l < 2000, although CMB experiments that aim for sensitivities sigma(m_nu) < 0.02 eV will need to include baryonic effects in modeling the CMB lensing potential. A combination of CMB lensing and galaxy lensing can help break the degeneracy between neutrino masses and baryonic feedback processes. We conclude that future large galaxy lensing surveys such as LSST and Euclid can only measure neutrino masses accurately if the matter power spectrum can be measured to similar accuracy.

  1. Galaxy Formation with Self-Consistently Modeled Stars and Massive Black Holes. I: Feedback-Regulated Star Formation and Black Hole Growth

    SciTech Connect (OSTI)

    Kim, Ji-hoon; Wise, John H.; /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Princeton U., Astrophys. Sci. Dept.; Alvarez, Marcelo A.; /Canadian Inst. Theor. Astrophys.; Abel, Tom; /KIPAC, Menlo Park /Stanford U., Phys. Dept.

    2011-11-04T23:59:59.000Z

    There is mounting evidence for the coevolution of galaxies and their embedded massive black holes (MBHs) in a hierarchical structure formation paradigm. To tackle the nonlinear processes of galaxy-MBH interaction, we describe a self-consistent numerical framework which incorporates both galaxies and MBHs. The high-resolution adaptive mesh refinement (AMR) code Enzo is modified to model the formation and feedback of molecular clouds at their characteristic scale of 15.2 pc and the accretion of gas onto an MBH. Two major channels of MBH feedback, radiative feedback (X-ray photons followed through full three-dimensional adaptive ray tracing) and mechanical feedback (bipolar jets resolved in high-resolution AMR), are employed. We investigate the coevolution of a 9.2 x 10{sup 11} M {circle_dot} galactic halo and its 10{sup 5} {circle_dot} M embedded MBH at redshift 3 in a cosmological CDM simulation. The MBH feedback heats the surrounding interstellar medium (ISM) up to 10{sup 6} K through photoionization and Compton heating and locally suppresses star formation in the galactic inner core. The feedback considerably changes the stellar distribution there. This new channel of feedback from a slowly growing MBH is particularly interesting because it is only locally dominant and does not require the heating of gas globally on the disk. The MBH also self-regulates its growth by keeping the surrounding ISM hot for an extended period of time.

  2. q-deformed logistic map with delay feedback

    E-Print Network [OSTI]

    Manish Dev Shrimali; Subhashish Banerjee

    2012-03-14T23:59:59.000Z

    The delay logistic map with two types of q-deformations: Tsallis and Quantum-group type are studied. The stability of the map and its bifurcation scheme is analyzed as a function of the deformation and delay feedback parameters. Chaos is suppressed in a certain region of deformation and feedback parameter space. The steady state obtained by delay feedback is maintained in one type of deformation while chaotic behavior is recovered in another type with increasing delay.

  3. Feedback Control Using Only Quantum Back-Action

    E-Print Network [OSTI]

    Kurt Jacobs

    2009-04-24T23:59:59.000Z

    The traditional approach to feedback control is to apply forces to a system by modifying the Hamiltonian. Here we show that quantum systems can be controlled without any Hamiltonian feedback, purely by exploiting the random quantum back-action of a continuous weak measurement. We demonstrate that, quite remarkably, the quantum back-action of such an adaptive measurement is just as effective at controlling quantum systems as traditional feedback.

  4. Locally Optimal Control of Quantum Systems with Strong Feedback

    E-Print Network [OSTI]

    Alireza Shabani; Kurt Jacobs

    2008-12-07T23:59:59.000Z

    For quantum systems with high purity, we find all observables that, when continuously monitored, maximize the instantaneous reduction in the von Neumann entropy. This allows us to obtain all locally optimal feedback protocols with strong feedback, and explicit expressions for the best such protocols for systems of size N optimal protocol is the optimal protocol for a given range of control times, and derive an upper bound on all optimal protocols with strong feedback.

  5. Self-induced frequency scanning and distributed Bragg reflection in semiconductor lasers with phase-conjugate feedback

    SciTech Connect (OSTI)

    Cronin-Golomb; Yariv

    1986-07-01T23:59:59.000Z

    A GaA1As semiconductor laser with feedback from a barium titanate photorefractive ring passive phase-conjugate mirror can be made to perform repeating or nonrepeating frequency scans over a 10-nm range toward either the blue or the red. The direction of scanning and whether the scans repeat may be controlled by adjusting the overlap of the interaction beams in the crystal. This overlap region may be adjusted so that the diode frequency spectrum, originally occupying about 10 longitudinal modes, scans and narrows as the conjugate signal builds up, coming to rest often in one, but sometimes two or three, longitudinal modes as a result of self-generated distributed-feedback effects. Also reported similar effects caused by feedback from the total-internal-reflection passive phase-conjugate mirror. The alignment-control mechanism of the ring mirror is, however, not available in this case.

  6. Self-induced frequency scanning and distributed Bragg reflection in semiconductor lasers with phase-conjugate feedback

    SciTech Connect (OSTI)

    Cronin-Golomb, M.; Yariv, A.

    1986-07-01T23:59:59.000Z

    A GaAlAs semiconductor laser with feedback from a barium titanate photorefractive ring passive phase-conjugate mirror can be made to perform repeating or nonrepeating frequency scans over a 10-nm range toward either the blue or the red. The direction of scanning and whether the scans repeat may be controlled by adjusting the overlap of the interaction beams in the crystal. This overlap region may be adjusted so that the diode frequency spectrum, originally occupying about 10 longitudinal modes, scans and narrows as the conjugate signal builds up, coming to rest often in one, but sometimes two or three, longitudinal modes as a result of self-generated distributed-feedback effects. We also report similar effects caused by feedback from the total-internal-reflection passive phase-conjugate mirror. The alignment-control mechanism of the ring mirror is, however, not available in this case.

  7. The effects of feedback on freeway operations 

    E-Print Network [OSTI]

    Baker, Robert Lewis

    1967-01-01T23:59:59.000Z

    Model IV represents the open feedback ? feed-forward model as shown in Figure 10 ' 0 QA ftt )Q 0 (1 - p ) Pg 0 P6 g o (1 - p, ) Figure 10, Model IV Assume f(t ) to be an Erlang distribution with mean tA -- aA/bA and f(t ) to be an Erlang... = ? ' = 150 a b a variance = ? ' = 57. 5 2 b a = 150 b u ? ''=575 b2 or b =~=40 57. 5 a = 150 b = 600. 0 P ' ' F, Average volume = 600 vehicles per hour Time period = 5 minutes 60 Nu. . ber of time periods per hour = ? = 12 5 600 Average number...

  8. A comparison of some relevance feedback techniques

    E-Print Network [OSTI]

    Cashman, Leslie Edward

    1972-01-01T23:59:59.000Z

    the relevant documents. Needless to say, perfect indexing does not exist in document retr1eval systems. Yet to use relevance feedback a basic assumption has to be made. Specifically 1t must be assumed that documents relevant to a given query will res1de... results. Out ut de ictin the functionin of each strate . The vector mentioned above is printed for each iteration of each strategy. At a glance it shows how the ranks of the relevant documents vacillate from one iteration to the next. In addition...

  9. Self-assessing target with automatic feedback

    DOE Patents [OSTI]

    Larkin, Stephen W.; Kramer, Robert L.

    2004-03-02T23:59:59.000Z

    A self assessing target with four quadrants and a method of use thereof. Each quadrant containing possible causes for why shots are going into that particular quadrant rather than the center mass of the target. Each possible cause is followed by a solution intended to help the marksman correct the problem causing the marksman to shoot in that particular area. In addition, the self assessing target contains possible causes for general shooting errors and solutions to the causes of the general shooting error. The automatic feedback with instant suggestions and corrections enables the shooter to improve their marksmanship.

  10. A comparison of some relevance feedback techniques 

    E-Print Network [OSTI]

    Cashman, Leslie Edward

    1972-01-01T23:59:59.000Z

    the relevant documents. Needless to say, perfect indexing does not exist in document retr1eval systems. Yet to use relevance feedback a basic assumption has to be made. Specifically 1t must be assumed that documents relevant to a given query will res1de... results. Out ut de ictin the functionin of each strate . The vector mentioned above is printed for each iteration of each strategy. At a glance it shows how the ranks of the relevant documents vacillate from one iteration to the next. In addition...

  11. Cloud feedback studies with a physics grid

    SciTech Connect (OSTI)

    Dipankar, Anurag [Max Planck Institute for Meteorology Hamburg; Stevens, Bjorn [Max Planck Institute for Meteorology Hamburg

    2013-02-07T23:59:59.000Z

    During this project the investigators implemented a fully parallel version of dual-grid approach in main frame code ICON, implemented a fully conservative first-order interpolation scheme for horizontal remapping, integrated UCLA-LES micro-scale model into ICON to run parallely in selected columns, and did cloud feedback studies on aqua-planet setup to evaluate the classical parameterization on a small domain. The micro-scale model may be run in parallel with the classical parameterization, or it may be run on a "physics grid" independent of the dynamics grid.

  12. PROJECT MANGEMENT PLAN EXAMPLES Feedback Examples

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742Energy ChinaofSchaeferAprilOverviewEfficiencyofHSSPIA -HazardFeedback Examples Example 74 8.2.3

  13. Effects of Feedback on Residential Electricity Consumption: A...

    Office of Scientific and Technical Information (OSTI)

    Haberkorn (1976-77) investigated feedback, information, and arebate system in 12 (6 control and 6 experimental) apartments where electricity was used for lighting, appliances,...

  14. Real-time Information, Uncertainty and Quantum Feedback Control

    E-Print Network [OSTI]

    Bo Qi; Daoyi Dong; Chunlin Chen; Lijun Liu; Zairong Xi

    2014-09-10T23:59:59.000Z

    Feedback is the core concept in cybernetics and its effective use has made great success in but not limited to the fields of engineering, biology, and computer science. When feedback is used to quantum systems, two major types of feedback control protocols including coherent feedback control (CFC) and measurement-based feedback control (MFC) have been developed. In this paper, we compare the two types of quantum feedback control protocols by focusing on the real-time information used in the feedback loop and the capability in dealing with parameter uncertainty. An equivalent relationship is established between quantum CFC and non-selective quantum MFC in the form of operator-sum representation. Using several examples of quantum feedback control, we show that quantum MFC can theoretically achieve better performance than quantum CFC in stabilizing a quantum state and dealing with Hamiltonian parameter uncertainty. The results enrich understanding of the relative advantages between quantum MFC and quantum CFC, and can provide useful information in choosing suitable feedback protocols for quantum systems.

  15. Beam-based Feedback for the Linac Coherent Light Source

    SciTech Connect (OSTI)

    Fairley, D.; Allison, S.; Chevtsov, S.; Chu, P.; Decker, F.J.; Emma, P.; Frisch, J.; Himel, T.; Kim, K.; Krejcik, P.; Loos, H.; Lahey, T.; Natampalli, P.; Peng, S.; Rogind, D.; Shoaee, H.; Straumann, T.; Williams, E.; White, G.; Wu, J.; Zelazney, M.; /SLAC

    2010-02-11T23:59:59.000Z

    Beam-based feedback control loops are required by the Linac Coherent Light Source (LCLS) program in order to provide fast, single-pulse stabilization of beam parameters. Eight transverse feedback loops, a 6 x 6 longitudinal feedback loop, and a loop to maintain the electron bunch charge were successfully prototyped in MATLAB for the LCLS, and have been maintaining stability of the LCLS electron beam at beam rates up to 30Hz. In the final commissioning phase of LCLS the beam will be operating at up to 120Hz. In order to run the feedback loops at beam rate, the feedback loops will be implemented in EPICS IOCs with a dedicated ethernet multi-cast network. This paper will discuss the design of the beam-based Fast Feedback System for LCLS. Topics include MATLAB feedback prototyping, algorithm for 120Hz feedback, network design for fast data transport, actuator and sensor design for single-pulse control and sensor readback, and feedback configuration and runtime control.

  16. artificial tactile feedback: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AD of transient model simulations and a new type of sen- sitivity experiments with artificial sea ice growth Born, Andreas 429 Vectorial Feedback with Carry Registers CERN...

  17. Data, Feedback, & Awareness Lead to Big Energy Savings | Department...

    Broader source: Energy.gov (indexed) [DOE]

    Data, Feedback, & Awareness Lead to Big Energy Savings Fact sheet describes how the Navy Region Southwest Metro San Diego Area (NRSMSD) regional energy management team achieved...

  18. adaptive feedback control: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    45 Adaptive Management of Irrigation with Feedback Control to Avoid Groundwater Pollution by Nitrate University of California eScholarship Repository Summary: cmhr) Soil...

  19. The Effect of Radiative Feedback on Bondi--Hoyle Flow around a Massive Star

    E-Print Network [OSTI]

    R. G. Edgar; Cathie Clarke

    2003-12-12T23:59:59.000Z

    We apply an algorithm for radiative feedback on a dusty flow (detailed in Edgar and Clarke (2003)) to the problem of Bondi--Hoyle accretion. This calculation is potentially relevant to the formation of massive stars in ultradense cores of stellar clusters. We find that radiative feedback is \\emph{more effective} than in the case of previous calculations in spherical symmetry. The Bondi-Hoyle geometry implies that material is flowing nearly tangentially when it experiences the sharp radiative impulse at the dust destruction radius, and consequently it is readily perturbed into outflowing orbits. We find that it is difficult for stellar masses to grow beyond around 10 M_sol (for standard interstellar dust abundances). We discuss the possible implications of this result for the formation mechanism of OB stars in cluster cores. We end by proposing a series of conditions which must be fulfilled if Bondi--Hoyle accretion is to continue.

  20. Feedback cooling of the normal modes of a massive electromechanical system to submillikelvin temperature

    E-Print Network [OSTI]

    A. Vinante; M. Bignotto; M. Bonaldi; M. Cerdonio; L. Conti; P. Falferi; N. Liguori; S. Longo; R. Mezzena; A. Ortolan; G. A. Prodi; F. Salemi; L. Taffarello; G. Vedovato; S. Vitale; J. -P. Zendri

    2008-09-18T23:59:59.000Z

    We apply a feedback cooling technique to simultaneously cool the three electromechanical normal modes of the ton-scale resonant-bar gravitational wave detector AURIGA. The measuring system is based on a dc Superconducting Quantum Interference Device (SQUID) amplifier, and the feedback cooling is applied electronically to the input circuit of the SQUID. Starting from a bath temperature of 4.2 K, we achieve a minimum temperature of 0.17 mK for the coolest normal mode. The same technique, implemented in a dedicated experiment at subkelvin bath temperature and with a quantum limited SQUID, could allow to approach the quantum ground state of a kilogram-scale mechanical resonator.

  1. Transition-edge sensor with enhanced electrothermal feedback for cryogenic particle detection

    DOE Patents [OSTI]

    Nam, Sae Woo (Palo Alto, CA); Cabrera, Blas (Stanford, CA)

    2001-01-01T23:59:59.000Z

    A superconducting transition-edge sensor with an electrothermal-feedback circuit, a heat sink thermally coupled thereto, a bias-feedback circuit electrically coupled with the electrothermal feedback circuit, and a current sensor electrically coupled with the bias-feedback circuit and inductively coupled with the electrothermal-feedback circuit.

  2. Essays on Macroeconomics

    E-Print Network [OSTI]

    Llosa, Luis Gonzalo

    2012-01-01T23:59:59.000Z

    A Microfounded Business Cycle Model . . . . . . . . . . .A Real Business Cycle Model . . . . . . . . . . . .A Real Business Cycle Model . . . . .

  3. Three essays in macroeconomics

    E-Print Network [OSTI]

    Farhi, Emmanuel

    2006-01-01T23:59:59.000Z

    Chapter 1 analyzes the theoretical and quantitative implications of optimal fiscal policy in a business cycle model with incomplete markets. I first consider the problem of a government facing expenditure shocks in an ...

  4. Essays in Quantitative Macroeconomics

    E-Print Network [OSTI]

    Neumuller, Seth

    2013-01-01T23:59:59.000Z

    quantitative model), I choose to focus on the volatility of permanent shocks to wages as the measure of risk for my analysis.

  5. Essays in macroeconomics

    E-Print Network [OSTI]

    Daula, Thomas Anthony; Daula, Thomas Anthony

    2012-01-01T23:59:59.000Z

    2.2.4 Multivariate GARCH . . . . . . . . . .US quarterly growth volatility: GARCH(1,1) . . . . . . . .to output volatility: GARCH(1,1) . . Correlation with US

  6. Essays in macroeconomics

    E-Print Network [OSTI]

    Daula, Thomas Anthony; Daula, Thomas Anthony

    2012-01-01T23:59:59.000Z

    A. , Sanjay Mithal, and Eric Neis, “Corporate Yield Spreads:power. Longstaff, Mithal, and Neis (2005) also found that a

  7. Macroeconomic Activity Module

    Annual Energy Outlook 2013 [U.S. Energy Information Administration (EIA)]

    explain the growth in GDP: the growth rate of nonfarm employment and the rate of productivity change associated with employment. As Table 2.1 indicates, in the Reference case,...

  8. Macroeconomic Activity Module

    Annual Energy Outlook 2013 [U.S. Energy Information Administration (EIA)]

    explain the growth in GDP: the growth rate of nonfarm employment and the rate of productivity change associated with employment. As Table 2.1 indicates, real GDP growth slows...

  9. Essays on international macroeconomics

    E-Print Network [OSTI]

    Gómez-González, Patricia

    2014-01-01T23:59:59.000Z

    This thesis examines several aspects of open economies. The first two chapters are about sovereign debt and its interactions with domestic financial markets. The third chapter, coauthored with my classmate Daniel Rees, ...

  10. Essays on Macroeconomics

    E-Print Network [OSTI]

    Llosa, Luis Gonzalo

    2012-01-01T23:59:59.000Z

    and volatility can lead to information being used in aexternalities lead to information being used inefficientlywhere public information can lead to welfare losses because

  11. Stabilising entanglement by quantum jump-based feedback

    E-Print Network [OSTI]

    A. R. R. Carvalho; J. J. Hope

    2007-05-24T23:59:59.000Z

    We show that direct feedback based on quantum jump detection can be used to generate entangled steady states. We present a strategy that is insensitive to detection inefficiencies and robust against errors in the control Hamiltonian. This feedback procedure is also shown to overcome spontaneous emission effects by stabilising states with high degree of entanglement.

  12. Applying Feedback Control to QoS Management Giovanna Ferrari

    E-Print Network [OSTI]

    Newcastle upon Tyne, University of

    Applying Feedback Control to QoS Management Giovanna Ferrari Distributed Systems Group, Department The importance of Feedback Control Theory used for dynamic systems has grown in recent years, due to the fundamental role played in modern technological systems. It represents a well developed analytic foundation

  13. Direct laser additive fabrication system with image feedback control

    DOE Patents [OSTI]

    Griffith, Michelle L. (Albuquerque, NM); Hofmeister, William H. (Nashville, TN); Knorovsky, Gerald A. (Albuquerque, NM); MacCallum, Danny O. (Edgewood, NM); Schlienger, M. Eric (Albuquerque, NM); Smugeresky, John E. (Pleasanton, CA)

    2002-01-01T23:59:59.000Z

    A closed-loop, feedback-controlled direct laser fabrication system is disclosed. The feedback refers to the actual growth conditions obtained by real-time analysis of thermal radiation images. The resulting system can fabricate components with severalfold improvement in dimensional tolerances and surface finish.

  14. Feedback stabilization of unstable propagating waves Eugene Mihaliuk,1

    E-Print Network [OSTI]

    Showalter, Kenneth

    Feedback stabilization of unstable propagating waves Eugene Mihaliuk,1 Tatsunari Sakurai,1 Florin Received 29 July 2001; revised manuscript received 10 March 2002; published 26 June 2002 Propagating wave s : 82.40.Ck, 47.54. r Propagating waves in active media arise from the cou- pling of a positive feedback

  15. State-Feedback Optimal Controllers for Deterministic Nonlinear Systems

    E-Print Network [OSTI]

    Won, Chang-Hee

    State-Feedback Optimal Controllers for Deterministic Nonlinear Systems Chang-Hee Won*, Abstract-- A full-state feedback optimal control problem is solved for a general deterministic nonlinear system)777-3368, won@und.edu II. HAMILTON-JACOBI EQUATION AND OPTIMAL CONTROLLER Consider the following system, dx

  16. Behavioral/Systems/Cognitive Visual Feedback Control of Hand Movements

    E-Print Network [OSTI]

    Knill, David C.

    -based control. Results were well fit by a control model that optimally integrates noisy, delayed sensory solely on feed- back about hand position. A visual feedback controller might steer to maintainBehavioral/Systems/Cognitive Visual Feedback Control of Hand Movements Jeffrey A. Saunders

  17. Modular Quantum Memories Using Passive Linear Optics and Coherent Feedback

    E-Print Network [OSTI]

    Modular Quantum Memories Using Passive Linear Optics and Coherent Feedback Hendra I. Nurdin photon pulsed optical field has a conceptually simple modular realization using only passive linear optics and coherent feedback. We exploit the idea that two decaying optical cavities can be coupled

  18. Integrating Tactile and Force Feedback with Finite Element Models

    E-Print Network [OSTI]

    , impedances of robot arms, and the computational model. We also describe an implementation of a compliance rendering system combining a low-impedance robot arm for large workspace kinesthetic force feedback, a high on a low-impedance robot arm, used here as a force feedback device. A real-time FEM model accepts user

  19. Handy feedback: Connecting smart meters with mobile phones

    E-Print Network [OSTI]

    and immediate feedback between 5% and 15% of the electrical household energy consumption can be saved [4 limitations of existing electricity consumption monitor- ing systems. It offers the possibility system provides both: real-time feedback on the entire electricity usage and on the consumption of many

  20. Combinatorial Optimization with Feedback Artificial Neural Networks \\Lambda

    E-Print Network [OSTI]

    Peterson, Carsten

    Combinatorial Optimization with Feedback Artificial Neural Networks \\Lambda Carsten Peterson@thep.lu.se Abstract A brief review is given for using feedback artificial neural networks (ANN) to obtain good Neural Networks, Oc­ tober 1995, Paris, France , eds. F. Fogelman­Soulie and P. Gallinari, EC2 & Cie

  1. STABILIZATION OF THE UNICYCLE VIA DYNAMIC FEEDBACK LINEARIZATION

    E-Print Network [OSTI]

    De Luca, Alessandro

    consider the feedback control problem for a wheeled mobile robot with the kinematics of a unicycle, a typical example of nonholonomic robotic system. It is shown that dynamic feedback linearization can be used to design a simple control law which is valid for trajectory tracking as well as point

  2. S. Boyd EE102 Dynamic analysis of feedback

    E-Print Network [OSTI]

    for some frequencies, small for others · step response of G shows time response of the closed-loop system of feedback 13­12 #12;Heater example: dynamic analysis proportional controller of lecture 12, PSfrag of feedback 13­14 #12;Let's assume · Tamb = 70 F · Tdes = 150 F (actually doesn't matter) · D is a unit step

  3. Observed Feedback between Winter Sea Ice and the North Atlantic Oscillation

    E-Print Network [OSTI]

    Strong, Courtenay; Magnusdottir, Gudrun; Stern, Hal

    2009-01-01T23:59:59.000Z

    variability and climate feedbacks in a global coupled model.Ocean JOURNAL OF CLIMATE feedback on the North Atlantic2009 STRONG ET AL. Observed Feedback between Winter Sea Ice

  4. A Usability Study of a Social Media Prototype for Building Energy Feedback and Operations

    E-Print Network [OSTI]

    Lehrer, David R.; Vasudev, Janani; Kaam, Soazig

    2014-01-01T23:59:59.000Z

    A pilot for a residential energy feedback program allowedscale residential pilots of real-time energy feedback thatresidential settings using a variety of interventions such as financial incentives, energy feedback,

  5. Design of VAX software for a generalized feedback system

    SciTech Connect (OSTI)

    Rouse, F.; Castillo, S.; Himmel, T.; Sass, B.; Shoaee, H.

    1991-05-01T23:59:59.000Z

    Fast feedback in the Stanford Linear Collider (SLC) not only works, but is necessary. We have several examples of currently running systems that have greatly improved the performance of the accelerator. In order to increase the number of feedback loops, it has become necessary to redesign the system to allow a database description of any feedback loop. We use digital control theory to formally describe each feedback loop in terms of a matrix equation. Then a new feedback loop requires only an update to the database, and perhaps the installation of a inter-micro communications link. This paper details the design of the VAX software required to implement the new system. 3 refs., 5 figs.

  6. Pulsed klystrons with feedback controlled mod-anode modulators

    SciTech Connect (OSTI)

    Reass, William A [Los Alamos National Laboratory; Baca, David M [Los Alamos National Laboratory; Jerry, Davis L [Los Alamos National Laboratory; Rees, Daniel E [Los Alamos National Laboratory

    2009-01-01T23:59:59.000Z

    This paper describes a fast rise and fall, totem-pole mod-anode modulators for klystron application. Details of these systems as recently installed utilizing a beam switch tube ''on-deck'' and a planar triode ''off-deck'' in a grid-catch feedback regulated configuration will be provided. The grid-catch configuration regulates the klystron mod-anode voltage at a specified set-point during switching as well as providing a control mechanism that flat-top regulates the klystron beam current during the pulse. This flat-topped klystron beam current is maintained while the capacitor bank droops. In addition, we will review more modern on-deck designs using a high gain, high voltage planar triode as a regulating and switching element. These designs are being developed, tested, and implemented for the Los Alamos Neutron Science Center (LANSCE) accelerator refurbishment project, ''LANSCE-R''. An advantage of the planar triode is that the tube can be directly operated with solid state linear components and provides for a very compact design. The tubes are inexpensive compared to stacked semiconductor switching assemblies and also provide a linear control capability. Details of these designs are provided as well as operational and developmental results.

  7. A feedback microprocessor for hadron colliders

    SciTech Connect (OSTI)

    Herrup, D.A.; Chapman, L.; Franck, A.; Groves, T.; Lublinsky, B.

    1992-12-01T23:59:59.000Z

    A feedback microprocessor has been built for the TEVATRON. It has been constructed to be applicable to hadron colliders in general. Its inputs are realtime accelerator measurements, data describing the state of the TEVATRON, and ramp tables. The microprocessor software includes a finite state machine. Each state corresponds to a specific TEVATRON operation and has a state-specific TEVATRON model. Transitions between states are initiated by the global TEVATRON clock. Each state includes a cyclic routine which is called periodically and where all calculations are performed. The output corrections are inserted onto a fast TEVATRON-wide link from which the power supplies will read the realtime corrections. We also store all of the input data and output corrections in a set of buffers which can easily be retrieved for diagnostic analysis. In this paper we will describe this device and its use to control the TEVATRON tunes as well as other possible applications.

  8. Combustion diagnostic for active engine feedback control

    DOE Patents [OSTI]

    Green, Jr., Johney Boyd (Knoxville, TN); Daw, Charles Stuart (Knoxville, TN); Wagner, Robert Milton (Knoxville, TN)

    2007-10-02T23:59:59.000Z

    This invention detects the crank angle location where combustion switches from premixed to diffusion, referred to as the transition index, and uses that location to define integration limits that measure the portions of heat released during the combustion process that occur during the premixed and diffusion phases. Those integrated premixed and diffusion values are used to develop a metric referred to as the combustion index. The combustion index is defined as the integrated diffusion contribution divided by the integrated premixed contribution. As the EGR rate is increased enough to enter the low temperature combustion regime, PM emissions decrease because more of the combustion process is occurring over the premixed portion of the heat release rate profile and the diffusion portion has been significantly reduced. This information is used to detect when the engine is or is not operating in a low temperature combustion mode and provides that feedback to an engine control algorithm.

  9. High Power Wideband AlGaN/GaN HEMT Feedback Amplifier Module with Drain and Feedback Loop

    E-Print Network [OSTI]

    Itoh, Tatsuo

    High Power Wideband AlGaN/GaN HEMT Feedback Amplifier Module with Drain and Feedback Loop amplifier module using AlGaN/GaN high electron mobility transistor (HEMT) has been developed that covers radars and communications systems. GaN-based HEMT's for high power applications at microwave frequencies

  10. Effects of optical feedback in a birefringence-Zeeman dual frequency laser at high optical feedback levels

    SciTech Connect (OSTI)

    Mao Wei; Zhang Shulian

    2007-04-20T23:59:59.000Z

    Optical feedback effects are studied in a birefringence-Zeeman dual frequency laser at high optical feedback levels. The intensity modulation features of the two orthogonally polarized lights are investigated in both isotropic optical feedback (IOF) and polarized optical feedback (POF). In IOF, the intensities of both beams are modulated simultaneously, and four zones, i.e., the e-light zone, the o-light and e-light zone, the o-light zone, and the no-light zone, are formed in a period corresponding to a half laser wavelength displacement of the feedback mirror. In POF, the two orthogonally polarized lights will oscillate alternately. Strong mode competition can be observed, and it affects the phase difference between the two beams greatly. The theoretical analysis is presented, which is in good agreement with the experimental results. The potential use of the experimental results is also discussed.

  11. An Adaptive Mechanism For Pre-recorded Multimedia Streaming

    E-Print Network [OSTI]

    An Adaptive Mechanism For Pre-recorded Multimedia Streaming Based On Traffic Conditions Gabriel, Dublin-4, IRELAND ++353-1-716-2914 Liam.Murphy@ucd.ie ABSTRACT The multimedia streams transmissions, done-recorded multimedia streams, regardless the network condition. The adaptive mechanism is implemented by a feedback

  12. The Fate of the First Galaxies. II. Effects of Radiative Feedback

    E-Print Network [OSTI]

    Massimo Ricotti; Nickolay Y. Gnedin; J. Michael Shull

    2002-04-09T23:59:59.000Z

    [abridged]We use 3D cosmological simulations with radiative transfer to study the formation and evolution of the first galaxies in a LCDM cosmology. We find that the first luminous objects ("small-halos") are characterized by a bursting star formation (SF) that is self-regulated by a feedback process acting on cosmological instead of galactic scales. The global star formation history is regulated by the mean number of ionizing photons that escape from each source, \\epsilon_{UV}\\fesc. It is almost independent of the assumed star formation efficiency parameter, \\epsilon_*, and the intensity of the dissociating background. The main feedback process that regulates the SF is the re-formation of H_2 in front of HII regions and inside relic HII regions. The HII regions remain confined inside filaments, maximizing the production of H_2 in overdense regions through cyclic destruction/reformation of H_2. If \\epsilon_{UV}\\fesc > 10^{-8}/\\epsilon_* the SF is self-regulated, photo-evaporation of "small-halo" objects dominate the metal pollution of the low density IGM, and the mass of produced metals depends only on \\fesc. If \\epsilon_{UV}\\fesc \\simlt 10^{-8}/\\epsilon_*, positive feedback dominates, and "small-halo" objects constitute the bulk of the mass in stars and metals at least until redshift z \\sim 10. "Small-halo" objects cannot reionize the universe because the feedback mechanism confines the HII regions inside the large scale structure filaments. In contrast to massive objects, which can reionize voids, "small-halo" objects partially ionize only the dense filaments while leaving the voids mostly neutral.

  13. Low speed control of a DC motor driving a mechanical system with fuzzy adaptive compensation 

    E-Print Network [OSTI]

    Hyun, Dongyoon

    1997-01-01T23:59:59.000Z

    A fuzzy adaptive feedforward control scheme in conjunction with classical feedback control is proposed for the low speed control of DC motors driving mechanical systems in the presence of friction. In the fuzzy adaptive scheme, a fuzzy logic based...

  14. Radiative Feedback in Relic HII Regions at High-Redshift

    E-Print Network [OSTI]

    Andrei Mesinger; Greg L. Bryan; Zoltan Haiman

    2009-09-13T23:59:59.000Z

    UV radiation from early astrophysical sources could have a large impact on subsequent star formation in nearby protogalaxies. Here we study the radiative feedback from the first, short-lived stars using hydrodynamical simulations with transient UV backgrounds (UVBs) and persistent Lyman-Werner backgrounds (LWBs) of varying intensity. We extend our prior work in Mesinger et al. (2006), by studying a more typical region whose proto-galaxies form at lower redshifts, z~13-20, in the epoch likely preceding the bulk of reionization. We confirm our previous results that feedback in the relic HII regions resulting from such transient radiation, is itself transient. Feedback effects dwindle away after ~30% of the Hubble time, and the same critical specific intensity of J_UV~0.1 x 10^{-21} ergs/s/cm^2/Hz/sr separates positive and negative feedback regimes. Additionally, we discover a second episode of eventual positive feedback in halos which have not yet collapsed when their progenitor regions were exposed to the transient UVB. This eventual positive feedback appears in all runs, regardless of the strength of the UVB. However, this feedback regime is very sensitive to the presence of Lyman-Werner radiation, and notable effects disappear under fairly modest background intensities of J_LW>10^{-3} x 10^{-21} ergs/s/cm^2/Hz/sr. We conclude that UV radiative feedback in relic HII regions, although a complicated process, seems unlikely to have a major impact on the progress of cosmological reionization, provided that present estimates of the lifetime and luminosity of a PopIII star are accurate. More likely is that the build-up of the LWB ultimately governs the feedback strength until a persistent UV background can be established. [abridged

  15. Feedback generation of quantum Fock states by discrete QND measures

    E-Print Network [OSTI]

    Mazyar Mirrahimi; Igor Dotsenko; Pierre Rouchon

    2009-05-04T23:59:59.000Z

    A feedback scheme for preparation of photon number states in a microwave cavity is proposed. Quantum Non Demolition (QND) measurement of the cavity field provides information on its actual state. The control consists in injecting into the cavity mode a microwave pulse adjusted to maximize the population of the desired target photon number. In the ideal case (perfect cavity and measures), we present the feedback scheme and its detailed convergence proof through stochastic Lyapunov techniques based on super-martingales and other probabilistic arguments. Quantum Monte-Carlo simulations performed with experimental parameters illustrate convergence and robustness of such feedback scheme.

  16. Coherent-feedback quantum control with a dynamic compensator

    E-Print Network [OSTI]

    Hideo Mabuchi

    2008-03-13T23:59:59.000Z

    I present an experimental realization of a coherent-feedback control system that was recently proposed for testing basic principles of linear quantum stochastic control theory [M. R. James, H. I. Nurdin and I. R. Petersen, to appear in IEEE Transactions on Automatic Control (2008), arXiv:quant-ph/0703150v2]. For a dynamical plant consisting of an optical ring-resonator, I demonstrate ~ 7 dB broadband disturbance rejection of injected laser signals via all-optical feedback with a tailored dynamic compensator. Comparison of the results with a transfer function model pinpoints critical parameters that determine the coherent-feedback control system's performance.

  17. Optical bistability in nonlinear system with two loops of feedback

    E-Print Network [OSTI]

    George P. Miroshnichenko; Alexander I. Trifanov

    2010-11-16T23:59:59.000Z

    A model of nonlinear optical system surrounded by two loops of feedback is investigated. The cell with the vapor of rubidium - type atoms is taken in the capacity of nonlinear element. Two modes of near-resonant electromagnetic field interacting with the cell are involved in the feedback. Two-dimensional optical bistability domain in location of input field intensities is obtained and dependence of its form and magnitude from the system parameters (photon detunings, feedback factor etc.) is investigated. "Input - output" relations corresponding to different trajectories in the bistability domain are obtained. Cross-hysteresis is studied.

  18. Self-consistent input-output formulation of quantum feedback

    SciTech Connect (OSTI)

    Yanagisawa, M. [Department of Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Hope, J. J. [Department of Quantum Science, The Australian National University, Canberra, ACT 0200 (Australia)

    2010-12-15T23:59:59.000Z

    A simple method of analyzing quantum feedback circuits is presented. The classical analysis of feedback circuits can be generalized to apply to quantum systems by mapping the field operators of various outputs to other inputs via the standard input-output formalism. Unfortunately, this has led to unphysical results such as the violation of the Heisenberg uncertainty principle for in-loop fields. This paper shows that this general approach can be redeemed by ensuring a self-consistently Hermitian Hamiltonian. The calculations are based on a noncommutative calculus of operator derivatives. A full description of several examples of quantum linear and nonlinear feedback for optical systems is presented.

  19. Efficiency of feedback process in cavity quantum electrodynamics

    E-Print Network [OSTI]

    H. T. Fung; P. T. Leung

    2007-08-02T23:59:59.000Z

    Utilizing the continuous frequency mode quantization scheme, we study from first principle the efficiency of a feedback scheme that can generate maximally entangled states of two atoms in an optical cavity through their interactions with a single input photon. The spectral function of the photon emitted from the cavity, which will be used as the input of the next round in the feedback process, is obtained analytically. We find that the spectral function of the photon is modified in each round and deviates from the original one. The efficiency of the feedback scheme consequently deteriorates gradually after several rounds of operation.

  20. On the feedback from super stellar clusters. I. The structure of giant HII regions and HII galaxies

    E-Print Network [OSTI]

    G. Tenorio-Tagle; C. Munoz-Tunon; E. Perez; S. Silich; E. Telles

    2006-01-27T23:59:59.000Z

    We review the structural properties of giant extragalactic HII regions and HII galaxies based on 2D hydrodynamic calculations, and propose an evolutionary sequence that accounts for their observed detailed structure. The model assumes a massive and young stellar cluster surrounded by a large collection of clouds. These are thus exposed to the most important star-formation feedback mechanisms: photoionization and the cluster wind. The models show how the two feedback mechanisms compete in the disruption of clouds and lead to two different hydrodynamic solutions: The storage of clouds into a long lasting ragged shell that inhibits the expansion of the thermalized wind, and the steady filtering of the shocked wind gas through channels carved within the cloud stratum. Both solutions are claimed to be concurrently at work in giant HII regions and HII galaxies, causing their detailed inner structure. This includes multiple large-scale shells, filled with an X-ray emitting gas, that evolve to finally merge with each other, giving the appearance of shells within shells. The models also show how the inner filamentary structure of the giant superbubbles is largely enhanced with matter ablated from clouds and how cloud ablation proceeds within the original cloud stratum. The calculations point at the initial contrast density between the cloud and the intercloud media as the factor that defines which of the two feedback mechanisms becomes dominant throughout the evolution. Animated version of the models can be found at http://www.iaa.csic.es/\\~{}eperez/ssc/ssc.html.

  1. A feedback microprocessor for hadron colliders

    SciTech Connect (OSTI)

    Herrup, D.A.; Chapman, L.; Franck, A.; Groves, T.; Lublinsky, B. (Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States))

    1995-02-01T23:59:59.000Z

    A feedback microprocessor has been built for the Tevatron. It has been constructed to be applicable to hadron colliders in general. Its inputs are realtime accelerator measurements, data describing the state of the Tevatron, and ramp tables. The microprocessor software includes a finite-state machine. Each state corresponds to a specific Tevatron operation and has a state-specific Tevatron model. Transitions between states are initiated by the global Tevatron clock. Each state includes a cyclic routine, which is called periodically and where all calculations are performed. The output corrections are inserted onto a fast Tevatron-wide link from which the power supplies will read the real time corrections. We also store all of the input data and output corrections in a set of buffers that can easily be retrieved for diagnostic analysis. In this paper we describe this device and its use to control the Tevatron tunes as well as other possible applications. [copyright] 1995 [ital American] [ital Institute] [ital of] [ital Physics

  2. An Optimization Framework for Driver Feedback Systems

    SciTech Connect (OSTI)

    Malikopoulos, Andreas [ORNL; Aguilar, Juan P. [Georgia Institute of Technology

    2013-01-01T23:59:59.000Z

    Modern vehicles have sophisticated electronic control units that can control engine operation with discretion to balance fuel economy, emissions, and power. These control units are designed for specific driving conditions (e.g., different speed profiles for highway and city driving). However, individual driving styles are different and rarely match the specific driving conditions for which the units were designed. In the research reported here, we investigate driving-style factors that have a major impact on fuel economy and construct an optimization framework to optimize individual driving styles with respect to these driving factors. In this context, we construct a set of polynomial metamodels to reflect the responses produced in fuel economy by changing the driving factors. Then, we compare the optimized driving styles to the original driving styles and evaluate the effectiveness of the optimization framework. Finally, we use this proposed framework to develop a real-time feedback system, including visual instructions, to enable drivers to alter their driving styles in response to actual driving conditions to improve fuel efficiency.

  3. agn feedback observations: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Christopher S; Heinz, Sebastian 2008-01-01 18 Feeding Versus Feedback in AGNs from Near-Infrared IFU Observations: The Case of Mrk79 CERN Preprints Summary: We have mapped the...

  4. Ratee Reactions: Negative Feedback as a Motivating Source

    E-Print Network [OSTI]

    Kabins, Adam Howard

    2012-02-14T23:59:59.000Z

    orientation and performance prove goal orientation were consistent significant moderators of the negative feedback-regulation relationship, such that individuals with high levels of Mastery prove goal orientation increased their autonomous regulation at higher...

  5. Code design for erasure channels with limited or noisy feedback

    E-Print Network [OSTI]

    Nagasubramanian, Karthik

    2008-10-10T23:59:59.000Z

    The availability of feedback in communication channels can significantly increase the reliability of transmission while decreasing the encoding and decoding complexity. Most of the applications like cellular telephony, satellite communications...

  6. Bursting in a Subcritical Hopf Oscillator with a Nonlinear Feedback

    E-Print Network [OSTI]

    Gautam C Sethia; Abhijit Sen

    2006-03-24T23:59:59.000Z

    Bursting is a periodic transition between a quiescent state and a state of repetitive spiking. The phenomenon is ubiquitous in a variety of neurophysical systems. We numerically study the dynamical properties of a normal form of subcritical Hopf oscillator (at the bifurcation point) subjected to a nonlinear feedback. This dynamical system shows an infinite-period or a saddle-node on a limit cycle (SNLC) bifurcation for certain strengths of the nonlinear feedback. When the feedback is time delayed, the bifurcation scenario changes and the limit cycle terminates through a homoclinic or a saddle separatrix loop (SSL) bifurcation. This system when close to the bifurcation point exhibits various types of bursting phenomenon when subjected to a slow periodic external stimulus of an appropriate strength. The time delay in the feedback enhances the spiking rate i.e. reduces the interspike interval in a burst and also increases the width or the duration of a burst.

  7. Code design for erasure channels with limited or noisy feedback

    E-Print Network [OSTI]

    Nagasubramanian, Karthik

    2009-05-15T23:59:59.000Z

    The availability of feedback in communication channels can significantly increase the reliability of transmission while decreasing the encoding and decoding complexity. Most of the applications like cellular telephony, satellite communications...

  8. Comparative analysis of aviation safety information feedback systems

    E-Print Network [OSTI]

    Funahashi, Yoshifuru

    2010-01-01T23:59:59.000Z

    In the aviation system, there are several feedback systems to prevent an accident. First of all, the accident and serious incident reporting and investigation system is established by the Chicago Convention. In general, ...

  9. Reverse quantum state engineering using electronic feedback loops

    E-Print Network [OSTI]

    Gerold Kiesslich; Clive Emary; Gernot Schaller; Tobias Brandes

    2012-11-30T23:59:59.000Z

    We propose an all-electronic technique to manipulate and control interacting quantum systems by unitary single-jump feedback conditioned on the outcome of a capacitively coupled electrometer and in particular a single-electron transistor. We provide a general scheme to stabilize pure states in the quantum system and employ an effective Hamiltonian method for the quantum master equation to elaborate on the nature of stabilizable states and the conditions under which state purification can be achieved. The state engineering within the quantum feedback scheme is shown to be linked with the solution of an inverse eigenvalue problem. Two applications of the feedback scheme are presented in detail: (i) stabilization of delocalized pure states in a single charge qubit and (ii) entanglement stabilization in two coupled charge qubits. In the latter example we demonstrate the stabilization of a maximally entangled Bell state for certain detector positions and local feedback operations.

  10. Feedback Policies for Measurement-based Quantum State Manipulation

    E-Print Network [OSTI]

    Shuangshuang Fu; Guodong Shi; Alexandre Proutiere; Matthew R. James

    2014-10-24T23:59:59.000Z

    In this paper, we propose feedback designs for manipulating a quantum state to a target state by performing sequential measurements. In light of Belavkin's quantum feedback control theory, for a given set of (projective or non-projective) measurements and a given time horizon, we show that finding the measurement selection policy that maximizes the probability of successful state manipulation is an optimal control problem for a controlled Markovian process. The optimal policy is Markovian and can be solved by dynamical programming. Numerical examples indicate that making use of feedback information significantly improves the success probability compared to classical scheme without taking feedback. We also consider other objective functionals including maximizing the expected fidelity to the target state as well as minimizing the expected arrival time. The connections and differences among these objectives are also discussed.

  11. Interactive Generator: A Self-Powered Haptic Feedback Device

    E-Print Network [OSTI]

    Anderson, Richard

    of temperature, stiffness and texture, are po- tentially valuable. Unfortunately, the electric motors, solenoids to convey in- formation when auditory and visual feedback may not be appropriate or available. However

  12. Kernels for Feedback Arc Set In Tournaments Stephane Bessy

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Kernels for Feedback Arc Set In Tournaments St´ephane Bessy Fedor V. Fomin Serge Gaspers Christophe´e de Montpellier 2, CNRS, 161 rue Ada, 34392 Montpellier, France. {bessy

  13. Microphones and Knock Sensors for Feedback Control of HCCI Engines

    E-Print Network [OSTI]

    Souder, Jason S; Mack, John Hunter; Hedrick, J. Karl; Dibble, Robert W

    2004-01-01T23:59:59.000Z

    Ion a current sensing for hcci combustion feedback. SAE2004. “Combustion timing in hcci engines deter- mined byof the combustion timing in an HCCI engine at high to medium

  14. Pulsed Feedback Defers Cellular Differentiation Joe H. Levine1

    E-Print Network [OSTI]

    Elowitz, Michael

    cycles leading up to sporulation. This pulse growth required a key positive feedback loop involving, Resuspension Media; Spo0AP , phosphorylated Spo0A * E-mail: melowitz@caltech.edu Introduction Cells are capable

  15. Optimization of neural network feedback control systems using automatic differentiation

    E-Print Network [OSTI]

    Rollins, Elizabeth, S.M. Massachusetts Institute of Technology

    2009-01-01T23:59:59.000Z

    Optimal control problems can be challenging to solve, whether using analytic or numerical methods. This thesis examines the application of an adjoint method for optimal feedback control, which combines various algorithmic ...

  16. Injection Related Background due to the Transverse Feedback

    SciTech Connect (OSTI)

    Decker, F.J.; Akre, R.; Fisher, A.; Iverson, R.; Weaver, M.; /SLAC

    2008-03-18T23:59:59.000Z

    The background in the BaBar detector is especially high during injection, when most components are actually having reduced voltages. The situation is worse for the beam in High Energy Ring (HER) when the LER beam is present. It was found that the transverse feedback system plays an important role when stacking more charge on top of existing bunches. Lowering the feedback gain helped and it was realized later that the best scenario would be to gate off the feedback for only the one bunch, which got additional charge injected into it. The explanation is that the blown-up, but centered, original HER bunch plus the small injected off-axis bunch (each with half the charge) would stay in the ring if not touched, but the feedback system sees half the offset and wants to correct it, therefore disturbing and scraping the blown-up part.

  17. Feedback Effects on Low-Mass Star Formation

    E-Print Network [OSTI]

    Hansen, Charles E; McKee, Christopher F; Fisher, Robert T

    2012-01-01T23:59:59.000Z

    Protostellar feedback, both radiation and bipolar outflows, dramatically affects the fragmentation and mass accretion from star-forming cores. We use ORION, an adaptive mesh refinement gravito-radiation-hydrodynamics code, to simulate the formation of a cluster of low-mass stars, including both radiative transfer and protostellar outflows. We ran four simulations to isolate the individual effects of radiation feedback and outflow feedback as well as the combination of the two. Outflows reduce protostellar masses and accretion rates each by a factor of three and therefore reduce protostellar luminosities by an order of magnitude. Thus, while radiation feedback suppresses fragmentation, outflows render protostellar radiation largely irrelevant for low-mass star formation above a mass scale of 0.05 M_sun. We find initial fragmentation of our cloud at half the global Jeans length, ~ 0.1 pc. With insufficient protostellar radiation to stop it, these 0.1 pc cores fragment repeatedly, forming typically 10 stars each...

  18. Feedback Controlled High Frequency Electrochemical Micromachining 

    E-Print Network [OSTI]

    Ozkeskin, Fatih Mert

    2008-10-10T23:59:59.000Z

    are different from those for silicon. A promising mass production method for micro/meso scale components is electrochemical micromachining. The complex system, however, requires high precision mechanical fixtures and sophisticated instrumentation for proper...

  19. POISONED FEEDBACK: THE IMPACT OF MALICIOUS USERS IN CLOSED-LOOP MULTIUSER MIMO SYSTEMS

    E-Print Network [OSTI]

    Swindlehurst, A. Lee

    POISONED FEEDBACK: THE IMPACT OF MALICIOUS USERS IN CLOSED-LOOP MULTIUSER MIMO SYSTEMS Amitav systems based on malicious feedback of CSI. In particular, we examine malicious or poisoned feedback of the trans- mitter are listed in Sec. 3. Numerical results that depict the impact of poisoned feedback

  20. Feedback Control of the Sawtooth Period through Real Time Control of the Ion Cyclotron Resonance Frequency

    E-Print Network [OSTI]

    Feedback Control of the Sawtooth Period through Real Time Control of the Ion Cyclotron Resonance Frequency

  1. Improving MU-MIMO Performance in LTE-(Advanced) by Efficiently Exploiting Feedback

    E-Print Network [OSTI]

    Gesbert, David

    (CDI/PMI). The standard supports finer granularity feedback i.e. sub-band feedback method, but it-band feedback for providing more frequent update of PMI. However, in order to support this feedback method, we), Downlink Control Information (DCI), Multi-user MIMO (MU-MIMO), Precoding Matrix Indi- cator (PMI

  2. Control of decoherence in open quantum systems using feedback

    E-Print Network [OSTI]

    Narayan Ganesan; Tzyh Jong Tarn

    2006-02-27T23:59:59.000Z

    Quantum feedback is assuming increasingly important role in quantum control and quantum information processing. In this work we analyze the application of such feedback techniques in eliminating decoherence in open quantum systems. In order to apply such system theoretic methods we first analyze the invariance properties of quadratic forms which corresponds to expected value of a measurement and present conditions for decouplability of measurement outputs of such time-varying open quantum systems from environmental effects.

  3. Domestic Audiences, Policy Feedback, and Sequential Decisions During Military Interventions

    E-Print Network [OSTI]

    Kuberski, Douglas Walter

    2011-02-22T23:59:59.000Z

    Committee Members, Michael Koch Guy Whitten Charles Hermann Head of Department, James Rogers December 2009 Major Subject: Political Science iii ABSTRACT Domestic Audiences, Policy Feedback, and Sequential Decisions During Military... how an individual citizen?s preference over commitment is impacted by policy feedback. The results of the experimental analyses suggest that citizens act as investors: they favor increasing commitment to military interventions when viewing negative...

  4. Adaptive method with intercessory feedback control for an intelligent agent

    DOE Patents [OSTI]

    Goldsmith, Steven Y.

    2004-06-22T23:59:59.000Z

    An adaptive architecture method with feedback control for an intelligent agent provides for adaptively integrating reflexive and deliberative responses to a stimulus according to a goal. An adaptive architecture method with feedback control for multiple intelligent agents provides for coordinating and adaptively integrating reflexive and deliberative responses to a stimulus according to a goal. Re-programming of the adaptive architecture is through a nexus which coordinates reflexive and deliberator components.

  5. Statistical physics of a model binary genetic switch with linear feedback

    E-Print Network [OSTI]

    Paolo Visco; Rosalind J. Allen; Martin R. Evans

    2009-03-31T23:59:59.000Z

    We study the statistical properties of a simple genetic regulatory network that provides heterogeneity within a population of cells. This network consists of a binary genetic switch in which stochastic flipping between the two switch states is mediated by a "flipping" enzyme. Feedback between the switch state and the flipping rate is provided by a linear feedback mechanism: the flipping enzyme is only produced in the on switch state and the switching rate depends linearly on the copy number of the enzyme. This work generalises the model of [Phys. Rev. Lett., 101, 118104] to a broader class of linear feedback systems. We present a complete analytical solution for the steady-state statistics of the number of enzyme molecules in the on and off states, for the general case where the enzyme can mediate flipping in either direction. For this general case we also solve for the flip time distribution, making a connection to first passage and persistence problems in statistical physics. We show that the statistics of the model are non-Poissonian, leading to a peak in the flip time distribution. The occurrence of such a peak is analysed as a function of the parameter space. We present a new relation between the flip time distributions measured for two relevant choices of initial condition. We also introduce a new correlation measure to show that this model can exhibit long-lived temporal correlations, thus providing a primitive form of cellular memory. Motivated by DNA replication as well as by evolutionary mechanisms involving gene duplication, we study the case of two switches in the same cell. This results in correlations between the two switches; these can either positive or negative depending on the parameter regime.

  6. Feedback in simulations of disc-galaxy major mergers

    E-Print Network [OSTI]

    T. J. Cox; Patrik Jonsson; Joel R. Primack; Rachel S. Somerville

    2007-09-25T23:59:59.000Z

    Using hydrodynamic simulations of disc-galaxy major mergers, we investigate the star formation history and remnant properties when various parametrizations of a simple stellar feedback model are implemented. The simulations include radiative cooling, a density-dependent star formation recipe and a model for feedback from massive stars. The feedback model stores supernova feedback energy within individual gas particles and dissipates this energy on a time-scale specified by two free parameters; tau_fb, which sets the dissipative time-scale, and n, which sets the effective equation of state in star-forming regions. Using a self-consistent disc galaxy, modelled after a local Sbc spiral, in both isolated and major-merger simulations, we investigate parametrizations of the feedback model that are selected with respect to the quiescent disc stability. These models produce a range of star formation histories that are consistent with the star formation relation found by Kennicutt. All major mergers produce a population of new stars that is highly centrally concentrated, demonstrating a distinct break in the r1/4 surface density profile, consistent with previous findings. The half-mass radius and one-dimensional velocity dispersion are affected by the feedback model used. Finally, we compare our results to those of previous simulations of star formation in disc-galaxy major mergers, addressing the effects of star formation normalization, the version of smoothed particle hydrodynamics (SPH) employed and assumptions about the interstellar medium.

  7. Signal Flows in Non-Markovian Linear Quantum Feedback Networks

    E-Print Network [OSTI]

    Re-Bing Wu; Jing Zhang; Yu-xi Liu; Tzyh-Jong Tarn

    2014-12-17T23:59:59.000Z

    Enabled by rapidly developing quantum technologies, it is possible to network quantum systems at a much larger scale in the near future. To deal with non-Markovian dynamics that is prevalent in solid-state devices, we propose a general transfer function based framework for modeling linear quantum networks, in which signal flow graphs are applied to characterize the network topology by flow of quantum signals. We define a noncommutative ring $\\mathbb{D}$ and use its elements to construct Hamiltonians, transformations and transfer functions for both active and passive systems. The signal flow graph obtained for direct and indirect coherent quantum feedback systems clearly show the feedback loop via bidirectional signal flows. Importantly, the transfer function from input to output field is derived for non-Markovian quantum systems with colored inputs, from which the Markovian input-output relation can be easily obtained as a limiting case. Moreover, the transfer function possesses a symmetry structure that is analogous to the well-know scattering transformation in \\sd picture. Finally, we show that these transfer functions can be integrated to build complex feedback networks via interconnections, serial products and feedback, which may include either direct or indirect coherent feedback loops, and transfer functions between quantum signal nodes can be calculated by the Riegle's matrix gain rule. The theory paves the way for modeling, analyzing and synthesizing non-Markovian linear quantum feedback networks in the frequency-domain.

  8. Quantum Theory of Cavityless Feedback Cooling of An Optically Trapped Nanoparticle

    E-Print Network [OSTI]

    Rodenburg, B; Vamivakas, A N; Bhattacharya, M

    2015-01-01T23:59:59.000Z

    We present a quantum theory of cavityless feedback cooling of an optically trapped harmonically oscillating subwavelength dielectric particle, a configuration recently realized in several experiments. Specifically, we derive a Markovian master equation that treats the mechanical as well as optical degrees of freedom quantum mechanically. Employing this equation, we solve for the nanoparticle phonon number dynamics exactly, and extract analytic expressions for the cooling timescale and the steady state phonon number. We present experimental data verifying the predictions of our model in the classical regime, and also demonstrate that quantum ground state preparation is within reach of ongoing experiments. Our work provides a quantitative framework for future theoretical modeling of the cavityless quantum optomechanics of optically trapped dielectric particles.

  9. Quantum Theory of Cavityless Feedback Cooling of An Optically Trapped Nanoparticle

    E-Print Network [OSTI]

    B. Rodenburg; L. P. Neukirch; A. N. Vamivakas; M. Bhattacharya

    2015-03-17T23:59:59.000Z

    We present a quantum theory of cavityless feedback cooling of an optically trapped harmonically oscillating subwavelength dielectric particle, a configuration recently realized in several experiments. Specifically, we derive a Markovian master equation that treats the mechanical as well as optical degrees of freedom quantum mechanically. Employing this equation, we solve for the nanoparticle phonon number dynamics exactly, and extract analytic expressions for the cooling timescale and the steady state phonon number. We present experimental data verifying the predictions of our model in the classical regime, and also demonstrate that quantum ground state preparation is within reach of ongoing experiments. Our work provides a quantitative framework for future theoretical modeling of the cavityless quantum optomechanics of optically trapped dielectric particles.

  10. Optical read out and feedback cooling of a nanostring optomechanical cavity

    E-Print Network [OSTI]

    Krause, Alex G; Painter, Oskar

    2015-01-01T23:59:59.000Z

    Optical measurement of the motion of a 940 kHz mechanical resonance of a silicon nitride nanostring resonator is demonstrated with a read out noise imprecision reaching 37 dB below that of the resonator's zero-point fluctuations. Via intensity modulation of the optical probe laser, radiation pressure feedback is used to cool and damp the mechanical mode from an initial room temperature occupancy of $\\bar{n}_{b} = 6.5 \\times 10^6$ ($T_{b}=295$K) down to a phonon occupation of $\\langle n \\rangle = 66 \\pm 10$, representing a mode temperature of $T_{m} \\approx 3$mK. The five decades of cooling is enabled by the system's large single-photon cooperativity $(C_{1} = 4)$ and high quantum efficiency of optical motion detection ($\\eta_{t} = 0.27$).

  11. Feedback Controlled High Frequency Electrochemical Micromachining

    E-Print Network [OSTI]

    Ozkeskin, Fatih Mert

    2008-10-10T23:59:59.000Z

    ........................................................................................................... 72 APPENDIX B ........................................................................................................... 76 APPENDIX C... of silicon make it popular in electronics, but lack of mechanical properties makes silicon vulnerable to many other applications that demands high stress and temperature. Micromachining of engineering alloys such as stainless steel, titanium or superalloys...

  12. Computer Science at Kent Electrophysiological Feedback in

    E-Print Network [OSTI]

    Kent, University of

    of whether a stimulus has been perceived: 1) reduced EEG power in the alpha band at posterior brain areas into a head-mounted wearable display that is electrically isolated from the surroundings by optical input to process them. The human brain has evolved a sophisticated attentional mechanism to pick and choose what

  13. Gas Feedback on Stellar Bar Evolution

    E-Print Network [OSTI]

    Ingo Berentzen; Isaac Shlosman; Inma Martinez-Valpuesta; Clayton Heller

    2007-05-27T23:59:59.000Z

    We analyze evolution of live disk-halo systems in the presence of various gas fractions, f_gas less than 8% in the disk. We addressed the issue of angular momentum (J) transfer from the gas to the bar and its effect on the bar evolution. We find that the weakening of the bar, reported in the literature, is not related to the J-exchange with the gas, but is caused by the vertical buckling instability in the gas-poor disks and by a steep heating of a stellar velocity dispersion by the central mass concentration (CMC) in the gas-rich disks. The gas has a profound effect on the onset of the buckling -- larger f_gas brings it forth due to the more massive CMCs. The former process leads to the well-known formation of the peanut-shaped bulges, while the latter results in the formation of progressively more elliptical bulges, for larger f_gas. The subsequent (secular) evolution of the bar differs -- the gas-poor models exhibit a growing bar while gas-rich models show a declining bar whose vertical swelling is driven by a secular resonance heating. The border line between the gas-poor and -rich models lies at f_gas ~ 3% in our models, but is model-dependent and will be affected by additional processes, like star formation and feedback from stellar evolution. The overall effect of the gas on the evolution of the bar is not in a direct J transfer to the stars, but in the loss of J by the gas and its influx to the center that increases the CMC. The more massive CMC damps the vertical buckling instability and depopulates orbits responsible for the appearance of peanut-shaped bulges. The action of resonant and non-resonant processes in gas-poor and gas-rich disks leads to a converging evolution in the vertical extent of the bar and its stellar dispersion velocities, and to a diverging evolution in the bulge properties.

  14. Feedback effects of aspherical supernovae explosions on galaxies

    E-Print Network [OSTI]

    Bekki, Kenji; Tsujimoto, Takuji

    2012-01-01T23:59:59.000Z

    We investigate how explosions of aspherical supernovae (A-SNe) can influence star formation histories and chemical evolution of dwarf galaxies by using a new chemodynamical model. We mainly present the numerical results of two comparative models so that the A-SN feedback effects on galaxies can be more clearly seen. SNe originating from stars with masses larger than 30M_sun are A-SNe in the "ASN" model whereas all SNe are spherical ones (S-SNe) in the "SSN" model. Each S-SN and A-SN are assumed to release feedback energy of 10^{51} erg and 10^{52} erg, respectively, and chemical yields and feedback energy of A-SN ejecta depend on angles between the axis of symmetry and the ejection directions. We find that star formation can become at least by a factor of ~3 lower in the ASN model in comparison with the SSN one owing to the more energetic feedback of A-SNe. As a result of this, chemical evolution can proceed very slowly in the ASN model. A-SN feedback effects can play a significant role in the formation of gi...

  15. Coherent versus measurement feedback: Linear systems theory for quantum information

    E-Print Network [OSTI]

    Naoki Yamamoto

    2014-10-10T23:59:59.000Z

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

  16. ULTRAFAST OUTFLOWS: GALAXY-SCALE ACTIVE GALACTIC NUCLEUS FEEDBACK

    SciTech Connect (OSTI)

    Wagner, A. Y.; Umemura, M. [Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577 (Japan); Bicknell, G. V., E-mail: ayw@ccs.tsukuba.ac.jp [Research School of Astronomy and Astrophysics, Australian National University, ACT 2611 (Australia)

    2013-01-20T23:59:59.000Z

    We show, using global three-dimensional grid-based hydrodynamical simulations, that ultrafast outflows (UFOs) from active galactic nuclei (AGNs) result in considerable feedback of energy and momentum into the interstellar medium (ISM) of the host galaxy. The AGN wind interacts strongly with the inhomogeneous, two-phase ISM consisting of dense clouds embedded in a tenuous, hot, hydrostatic medium. The outflow floods through the intercloud channels, sweeps up the hot ISM, and ablates and disperses the dense clouds. The momentum of the UFO is primarily transferred to the dense clouds via the ram pressure in the channel flow, and the wind-blown bubble evolves in the energy-driven regime. Any dependence on UFO opening angle disappears after the first interaction with obstructing clouds. On kpc scales, therefore, feedback by UFOs operates similarly to feedback by relativistic AGN jets. Negative feedback is significantly stronger if clouds are distributed spherically rather than in a disk. In the latter case, the turbulent backflow of the wind drives mass inflow toward the central black hole. Considering the common occurrence of UFOs in AGNs, they are likely to be important in the cosmological feedback cycles of galaxy formation.

  17. Self-Management of Patient Body Position, Pose, and Motion Using Wide-Field, Real-Time Optical Measurement Feedback: Results of a Volunteer Study

    SciTech Connect (OSTI)

    Parkhurst, James M. [Developing Technologies, Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester (United Kingdom); Price, Gareth J., E-mail: gareth.price@christie.nhs.uk [Developing Technologies, Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester (United Kingdom); Faculty of Medical and Human Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester (United Kingdom); Sharrock, Phil J. [Developing Technologies, Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester (United Kingdom); Jackson, Andrew S.N. [Clinical Oncology, Southampton University Hospitals Foundation Trust, Southampton (United Kingdom); Stratford, Julie [Department of Radiotherapy, The Christie NHS Foundation Trust, Manchester (United Kingdom); Moore, Christopher J. [Developing Technologies, Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester (United Kingdom); Faculty of Medical and Human Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester (United Kingdom)

    2013-12-01T23:59:59.000Z

    Purpose: We present the results of a clinical feasibility study, performed in 10 healthy volunteers undergoing a simulated treatment over 3 sessions, to investigate the use of a wide-field visual feedback technique intended to help patients control their pose while reducing motion during radiation therapy treatment. Methods and Materials: An optical surface sensor is used to capture wide-area measurements of a subject's body surface with visualizations of these data displayed back to them in real time. In this study we hypothesize that this active feedback mechanism will enable patients to control their motion and help them maintain their setup pose and position. A capability hierarchy of 3 different level-of-detail abstractions of the measured surface data is systematically compared. Results: Use of the device enabled volunteers to increase their conformance to a reference surface, as measured by decreased variability across their body surfaces. The use of visual feedback also enabled volunteers to reduce their respiratory motion amplitude to 1.7 ± 0.6 mm compared with 2.7 ± 1.4 mm without visual feedback. Conclusions: The use of live feedback of their optically measured body surfaces enabled a set of volunteers to better manage their pose and motion when compared with free breathing. The method is suitable to be taken forward to patient studies.

  18. Comparing resolved-sideband cooling and measurement-based feedback cooling on an equal footing: analytical results in the regime of ground-state cooling

    E-Print Network [OSTI]

    Kurt Jacobs; Hendra I. Nurdin; Frederick W. Strauch; Matthew James

    2015-03-19T23:59:59.000Z

    We show that in the regime of ground-state cooling, simple expressions can be derived for the performance of resolved-sideband cooling --- an example of coherent feedback control --- and optimal linear measurement-based feedback cooling for a harmonic oscillator. These results are valid to leading order in the small parameters that define this regime. They provide insight into the origins of the limitations of coherent and measurement-based feedback for linear systems, and the relationship between them. These limitations are not fundamental bounds imposed by quantum mechanics, but are due to the fact that both cooling methods are restricted to use only a linear interaction with the resonator. We compare the performance of the two methods on an equal footing --- that is, for the same interaction strength --- and confirm that coherent feedback is able to make much better use of the linear interaction than measurement-based feedback. We find that this performance gap is caused not by the back-action noise of the measurement but by the projection noise. We also obtain simple expressions for the maximal cooling that can be obtained by both methods in this regime, optimized over the interaction strength.

  19. DRIVING OUTFLOWS WITH RELATIVISTIC JETS AND THE DEPENDENCE OF ACTIVE GALACTIC NUCLEUS FEEDBACK EFFICIENCY ON INTERSTELLAR MEDIUM INHOMOGENEITY

    SciTech Connect (OSTI)

    Wagner, A. Y.; Umemura, M. [Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Bicknell, G. V., E-mail: ayw@ccs.tsukuba.ac.jp [Research School of Astronomy and Astrophysics, Australian National University, ACT 2611 (Australia)

    2012-10-01T23:59:59.000Z

    We examine the detailed physics of the feedback mechanism by relativistic active galactic nucleus (AGN) jets interacting with a two-phase fractal interstellar medium (ISM) in the kpc-scale core of galaxies using 29 three-dimensional grid-based hydrodynamical simulations. The feedback efficiency, as measured by the amount of cloud dispersal generated by the jet-ISM interactions, is sensitive to the maximum size of clouds in the fractal cloud distribution but not to their volume filling factor. Feedback ceases to be efficient for Eddington ratios P{sub jet}/L{sub edd} {approx}< 10{sup -4}, although systems with large cloud complexes {approx}> 50 pc require jets of Eddington ratio in excess of 10{sup -2} to disperse the clouds appreciably. Based on measurements of the bubble expansion rates in our simulations, we argue that sub-grid AGN prescriptions resulting in negative feedback in cosmological simulations without a multi-phase treatment of the ISM are good approximations if the volume filling factor of warm-phase material is less than 0.1 and the cloud complexes are smaller than {approx}25 pc. We find that the acceleration of the dense embedded clouds is provided by the ram pressure of the high-velocity flow through the porous channels of the warm phase, flow that has fully entrained the shocked hot-phase gas it has swept up, and is additionally mass loaded by ablated cloud material. This mechanism transfers 10% to 40% of the jet energy to the cold and warm gas, accelerating it within a few 10 to 100 Myr to velocities that match those observed in a range of high- and low-redshift radio galaxies hosting powerful radio jets.

  20. Powerful Outflows and Feedback from Active Galactic Nuclei

    E-Print Network [OSTI]

    King, Andrew

    2015-01-01T23:59:59.000Z

    Active Galactic Nuclei (AGN) represent the growth phases of the supermassive black holes in the center of almost every galaxy. Powerful, highly ionized winds, with velocities $\\sim 0.1- 0.2c$ are a common feature in X--ray spectra of luminous AGN, offering a plausible physical origin for the well known connections between the hole and properties of its host. Observability constraints suggest that the winds must be episodic, and detectable only for a few percent of their lifetimes. The most powerful wind feedback, establishing the $M -\\sigma$ relation, is probably not directly observable at all. The $M - \\sigma$ relation signals a global change in the nature of AGN feedback. At black hole masses below $M-\\sigma$ feedback is confined to the immediate vicinity of the hole. At the $M-\\sigma$ mass it becomes much more energetic and widespread, and can drive away much of the bulge gas as a fast molecular outflow.

  1. Feedback-controlled transport in an interacting colloidal system

    E-Print Network [OSTI]

    Ken Lichtner; Sabine H. L. Klapp

    2010-11-03T23:59:59.000Z

    Based on dynamical density functional theory (DDFT) we consider a non-equilibrium system of interacting colloidal particles driven by a constant tilting force through a periodic, symmetric "washboard" potential. We demonstrate that, despite of pronounced spatio-temporal correlations, the particle current can be reversed by adding suitable feedback control terms to the DDFT equation of motion. We explore two distinct control protocols with time delay, focussing on either the particle positions or the density profile. Our study shows that the DDFT is an appropriate framework to implement time-delayed feedback control strategies widely used in other fields of nonlinear physics

  2. Feedback control of the squeezing of the fluorescence light

    E-Print Network [OSTI]

    Alberto Barchielli; Matteo Gregoratti

    2009-10-09T23:59:59.000Z

    Among the formulations of the theory of quantum measurements in continuous time, quantum trajectory theory is very suitable for the introduction of measurement based feedback and closed loop control of quantum systems. In this paper we present such a construction in the concrete case of a two-level atom stimulated by a coherent, monochromatic laser. In particular, we show how fast feedback \\`a la Wiseman and Milburn can be introduced in the formulation of the theory. Then, the spectrum of the free fluorescence light is studied and typical quantum phenomena, squeezing and sub-natural line-narrowing, are presented.

  3. Optimal Unravellings for Feedback Control in Linear Quantum Systems

    E-Print Network [OSTI]

    H. M . Wiseman; A. C. Doherty

    2005-02-26T23:59:59.000Z

    For quantum systems with linear dynamics in phase space much of classical feedback control theory applies. However, there are some questions that are sensible only for the quantum case, such as: given a fixed interaction between the system and the environment what is the optimal measurement on the environment for a particular control problem? We show that for a broad class of optimal (state-based) control problems (the stationary Linear-Quadratic-Gaussian class), this question is a semi-definite program. Moreover, the answer also applies to Markovian (current-based) feedback.

  4. Feedback control of major disruptions in International Thermonuclear Experimental Reactor

    SciTech Connect (OSTI)

    Sen, A. K. [Plasma Physics Laboratory, Columbia University, New York, New York 10026 (United States)

    2011-08-15T23:59:59.000Z

    It is argued that major disruptions in ITER can be avoided by the feedback control of the causative MHD precursors. The sensors will be 2D-arrays of ECE detectors and the suppressors will be modulated ECH beams injected radially to produce non-thermal radial pressures to counter the radial dynamics of MHD modes. The appropriate amplitude and phase of this signal can stabilize the relevant MHD modes and prevent their evolution to a major disruption. For multimode MHD precursors, an optimal feedback scheme with a Kalman filter is discussed.

  5. The Cusp/Core problem: supernovae feedback versus the baryonic clumps and dynamical friction model

    E-Print Network [OSTI]

    Del Popolo, A

    2015-01-01T23:59:59.000Z

    In the present paper, we compare the predictions of two well known mechanisms considered able to solve the cusp/core problem (a. supernova feedback; b. baryonic clumps-DM interaction) by comparing their theoretical predictions to recent observations of the inner slopes of galaxies with masses ranging from dSphs to normal spirals. We compare the $\\alpha$-$V_{\\rm rot}$ and the $\\alpha$-$M_{\\ast}$ relationships, predicted by the two models with high resolution data coming from \\cite{Adams2014}, \\cite{Simon2005}, LITTLE THINGS \\citep{Oh2014}, THINGS dwarves \\citep{Oh2011a,Oh2011b}, THINGS spirals \\citep{Oh2014}, Sculptor, Fornax and the Milky Way. The comparison of the theoretical predictions with the complete set of data shows that the two models perform similarly, while when we restrict the analysis to a smaller subsample of higher quality, we show that the method presented in this paper (baryonic clumps-DM interaction) performs better than the one based on supernova feedback. We also show that, contrarily to t...

  6. Quantifying Climate Feedbacks from Abrupt Changes in High-Latitude Trace-Gas Emissions

    SciTech Connect (OSTI)

    Schlosser, Courtney Adam [MIT; Walter-Anthony, Katey [University of Alaska; Zhuang, Qianlai [Purdue University; Melillo, Jerry [Marine Biological Laboratory

    2013-04-26T23:59:59.000Z

    Our overall goal was to quantify the potential for threshold changes in natural emission rates of trace gases, particularly methane and carbon dioxide, from pan-arctic terrestrial systems under the spectrum of anthropogenically forced climate warming, and the extent to which these emissions provide a strong feedback mechanism to global climate warming. This goal is motivated under the premise that polar amplification of global climate warming will induce widespread thaw and degradation of the permafrost, and would thus cause substantial changes in the extent of wetlands and lakes, especially thermokarst (thaw) lakes, over the Arctic. Through a coordinated effort of field measurements, model development, and numerical experimentation with an integrated assessment model framework, we have investigated the following hypothesis: There exists a climate-warming threshold beyond which permafrost degradation becomes widespread and thus instigates strong and/or sharp increases in methane emissions (via thermokarst lakes and wetland expansion). These would outweigh any increased uptake of carbon (e.g. from peatlands) and would result in a strong, positive feedback to global climate warming.

  7. 1. Introduction The atmospheric greenhouse effect is the basic mechanism

    E-Print Network [OSTI]

    1. Introduction The atmospheric greenhouse effect is the basic mechanism whereby absorbed solar system of the Earth is endowed with a moderately strong greenhouse effect that is characterized by non CO2. There is a strong feedback contribution to the greenhouse effect by water vapor and clouds

  8. Teaching Feedback to First-year Medical Students: Long-term Skill Retention and Accuracy of Student Self-assessment

    E-Print Network [OSTI]

    Kruidering-Hall, Marieke; O’Sullivan, Patricia S.; Chou, Calvin L.

    2009-01-01T23:59:59.000Z

    DK. Oral versus written feedback in medical clinic. J Gen2002; 77(12):1185–8. 3. Ende J. Feedback in clinical medicalWC, ten Cate OTJ. What is feedback in clinical education.

  9. An Evaluation of the Interactive Effects of Feedback Sequence and Timing on Efficacy and Preference

    E-Print Network [OSTI]

    Henley, Amy Jessica

    2014-05-31T23:59:59.000Z

    Feedback is an effective method for increasing employee performance in a wide range of settings, although questions remain regarding the most effective characteristics of feedback. Despite the fact that there is little research on the sequence...

  10. Feedback vertex sets and disjoint cycles in planar (di)graphs

    E-Print Network [OSTI]

    graph has a feedback vertex set of cardinality at most k then its treewidth. is bounded ... in linear time, and this is used to nd an algorithm computing a feedback.

  11. RFI Seeks Feedback on Third-party Maintenance Strategy for AMO...

    Energy Savers [EERE]

    RFI Seeks Feedback on Third-party Maintenance Strategy for AMO's Software Tools RFI Seeks Feedback on Third-party Maintenance Strategy for AMO's Software Tools July 28, 2014 -...

  12. The role of linguistic contrasts in the auditory feedback control of Speech

    E-Print Network [OSTI]

    Niziolek, Caroline A

    2010-01-01T23:59:59.000Z

    Speakers use auditory feedback to monitor their own speech, ensuring that the intended output matches the observed output. By altering the acoustic feedback signal before it reaches the speaker's ear, we can induce auditory ...

  13. & Mechanical Engineering

    E-Print Network [OSTI]

    Zhou, Chongwu

    , robotics, and the development of new tools for integrated approaches to concurrent engineeringAME Aerospace & Mechanical Engineering #12;Aerospace and Mechanical Engineers design complex Engineering (AME) students conduct basic and applied research within and across the usual disciplinary

  14. Iterated Learning with Human subjects: adding communication and feedback 

    E-Print Network [OSTI]

    Murray, Laura

    2010-11-24T23:59:59.000Z

    with no intentional design on behalf of the subject. However, filtering for homonymy was necessary to produce a language that adapted to be learnable by becoming more structured and expressive. What I proposed was to introduce communication and feedback to investigate...

  15. ISM dust feedback from low to high mass stars

    E-Print Network [OSTI]

    Falceta-Goncalves; D.

    2007-10-26T23:59:59.000Z

    The dust component of the interstellar medium (ISM) has been extensively studied in the past decades. Late-type stars have been assumed as the main source of dust to the ISM, but recent observations show that supernova remnants may play a role on the ISM dust feedback. In this work, I study the importance of low and high mass stars, as well as their evolutionary phase, on the ISM dust feedback process. I also determine the changes on the obtained results considering different mass distribution functions and star formation history. We describe a semi-empirical calculation of the relative importance of each star at each evolutionary phase in the dust ejection to the ISM. I compare the obtained results for two stellar mass distribution functions, the classic Salpeter initial mass function and the present day mass function. I used the evolutionary track models for each stellar mass, and the empirical mass-loss rates and dust-to-gas ratio. The relative contribution of each stellar mass depends on the used distribution. Ejecta from massive stars represent the most important objects for the ISM dust replenishment using the Salpeter IMF. On the other hand, for the present day mass function low and intermediate mass stars are dominant. Late-type giant and supergiant stars dominate the ISM dust feedback in our actual Galaxy, but this may not the case of galaxies experiencing high star formation rates, or at high redshifts. In those cases, SNe are dominant in the dust feedback process.

  16. Distributed Precoding for MISO Interference Channels with Channel Mean Feedback

    E-Print Network [OSTI]

    Ulukus, Sennur

    Distributed Precoding for MISO Interference Channels with Channel Mean Feedback: Algorithms precoding algorithms for multiple-input single-output (MISO) interference channels, where each trans- mitter- antenna wireless interference channels [5]-[7]. For multiple- input single-output (MISO) interference

  17. Nonlinear Flight Control Using Neural Networks and Feedback Linearization

    E-Print Network [OSTI]

    Nonlinear Flight Control Using Neural Networks and Feedback Linearization Byoung So0 Kim1, Anthony approaches to aircraft flight control involve linearization of these dynamicsabout a set of pre eliminate many of the undesirable features of linear control. Control of nonlinear systems by inverting

  18. On Optimal Distributed Output-Feedback Control over Acyclic Graphs

    E-Print Network [OSTI]

    Gattami, Ather

    2012-01-01T23:59:59.000Z

    In this paper, we consider the problem of distributed optimal control of linear dynamical systems with a quadratic cost criterion. We study the case of output feedback control for two interconnected dynamical systems, and show that the linear optimal solution can be obtained from a combination of two uncoupled Riccati equations and two coupled Riccati equations.

  19. Robust Measurement Feedback Control of an Inclined Cable

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    a robust control strategy based on modern control tools for distributed parameter systems, hal-00784727 on the construction of a standard linear infinite dimensional state space system and an H feedback control). !"#$%& # ' ( )"#$%& "*++$!++&, - *. , , Fig. 1. Inclined Cable This paper is devoted to the design of control laws for a vi- brating system

  20. INVITED SESSION NUMBER: 157 Event-Based Feedback Control

    E-Print Network [OSTI]

    Moehlis, Jeff

    . INTRODUCTION Symptoms of neuromotor disorders, such as Parkinson's Disease (PD), have been linked-compulsive disorder, and even depression [1]. Since its approval by the FDA in 1997 for use in advanced cases of PD models, that are each equipped with both a stimulus and feedback electrode. We seek to develop a control

  1. Ecosystem feedbacks arising from wind transport in drylands: Results

    E-Print Network [OSTI]

    Ecosystem feedbacks arising from wind transport in drylands: Results from field experiments fire frequency Woody mortality Introduction of exotic grasses Is cover dominated by annuals or short intensity precipitation Low wind speeds Low P/PE High variability High intensity precipitation High wind

  2. Feedback damper system for quadrupole oscillations after transition at RHIC.

    SciTech Connect (OSTI)

    Abreu,N.; Blaskiewicz, M.; Brennan, J.M.; Schultheiss, C.

    2008-06-23T23:59:59.000Z

    The heavy ion beam at RHIC undergoes strong quadrupole oscillations just after it crosses transition, which leads to an increase in bunch length making rebucketing less effective. A feedback system was built to damp these quadrupole oscillations and in this paper the characteristics of the system and the results obtained are presented and discussed.

  3. KEYNOTE PAPER Principles of good assessment and feedback

    E-Print Network [OSTI]

    Azzopardi, Leif

    KEYNOTE PAPER Principles of good assessment and feedback: Theory and practice David Nicol for the theory and practice of assessment in higher education. It presents 10 principles of good assessment underpinning good assessment practice in higher education. In one paper, I (with a colleague) formulated seven

  4. Design and implementation of the feedback systems Web laboratory

    E-Print Network [OSTI]

    Viedma Núñez, Gerardo

    2005-01-01T23:59:59.000Z

    This thesis describes the design and implementation of a remote web-based laboratory (WebLab) for MIT's 6.302 Feedback Systems course. The WebLab system proposed consists of a three-tiered architecture where client and ...

  5. Multi-Query Feedback Motion Planning with LQR-Roadmaps

    E-Print Network [OSTI]

    Jackson, Daniel

    Multi-Query Feedback Motion Planning with LQR-Roadmaps Anirudha Majumdar School of Engineering "roadmap", with each segment representing a locally optimal trajectory of the system and a continuous) - and for parameterized finite-time invariance around a trajectory, as well as a "roadmap" construction al- gorithm

  6. How Can I Say This? giving feedback at the rca

    E-Print Network [OSTI]

    Subramanian, Sriram

    on their minds than teaching and learning. At those times it may be best practice to reschedule meetings decisions for themselves. For example, a piece of work may need moving on in response to previous feedback or encouragement, but of the decision or answer, even when the student demands it. I'm confident that my students

  7. Does Beamforming achieve Outage Capacity with Direction Feedback?

    E-Print Network [OSTI]

    Jafar, Syed A.

    Does Beamforming achieve Outage Capacity with Direction Feedback? Sudhir Srinivasa and Syed Ali Jafar Sriram Vishwanath Electrical Engineering and Computer Science Electrical and Computer Engineering: syed@ece.uci.edu, sudhirs@uci.edu Email: sriram@ece.utexas.edu Abstract We explore the outage capacity

  8. MATH43032/63032, May 2014 Exam, and Feedback

    E-Print Network [OSTI]

    Sidorov, Nikita

    MATH43032/63032, May 2014 Exam, Solutions1 and Feedback Solutions A1. |s i si S = or i si S = and for the least such i, si S S. The Representation Theorem for Rational Consequence Relations: Every ra- tional are more detailed than I would expect in the exam. That's because I want them to also serve an educational

  9. The Design of Eco-Feedback Technology Jon Froehlich1

    E-Print Network [OSTI]

    Anderson, Richard

    behaviors with a goal of reducing environmental impact. The history of eco-feedback extends back more than environmental impact (adapted from [39] and [28], see Figure 1 for examples). Despite this goal, few HCI eco 40 years to the origins of environmental psychology. Despite its stated purpose, few HCI eco

  10. Robust Path Planning and Feedback Design under Stochastic Uncertainty

    E-Print Network [OSTI]

    Williams, Brian C.

    . Introduction Autonomous vehicles such as Unmanned Air Vehicles (UAVs) need to be able to plan trajectories; prior work showed that a UAV operating at a constant altitude as well as other autonomous vehicles canRobust Path Planning and Feedback Design under Stochastic Uncertainty Lars Blackmore Autonomous

  11. Providing Intelligent Language Feedback for Augmentative Communication Users

    E-Print Network [OSTI]

    McCoy, Kathleen F.

    . Pennington and Kathleen F. McCoy Applied Science and Engineering Laboratories Department of ComputerProviding Intelligent Language Feedback for Augmentative Communication Users Christopher A and Information Sciences University of Delaware duPont Hospital for Children Wilmington, DE 19899 penningt

  12. Providing Intelligent Language Feedback for Augmentative Communication Users

    E-Print Network [OSTI]

    McCoy, Kathleen F.

    . Pennington and Kathleen F. McCoy Applied Science and Engineering Laboratories Department of ComputerProviding Intelligent Language Feedback for Augmentative Communication Users Christopher A and Information Sciences University of Delaware / duPont Hospital for Children Wilmington, DE 19899 penningt

  13. Fire Feedbacks with Vegetation and Alternative Stable States

    E-Print Network [OSTI]

    Beckage, Brian

    landscape composition and that (ii) hurricane disturbances can mediate the frequency of fire that leads frequency. Our results indicate that gradual changes in global climate that influence disturbance frequency.Beckage@uvm.edu Positive feedbacks between vegetation and fire disturbance may lead to nonlinear ecosystem responses

  14. ORIGINAL PAPER Hunter feedback of individually marked wild boar

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ORIGINAL PAPER Hunter feedback of individually marked wild boar Sus scrofa L.: dispersal 2009 # Springer-Verlag 2009 Abstract Increasing wild boar (Sus scrofa L.) population densities all over of wild boar in southwestern Mecklenburg-Western Pomerania. From 152 marked wild boar, 105 have been

  15. Electrooptic light modulator with improved response linearity using optical feedback

    E-Print Network [OSTI]

    Bhatranand, Apichai

    2005-11-01T23:59:59.000Z

    to 71.83 dB, limited by third-order nonlinearity. In tests at constant modulation depth, an improvement of as much as 9.6 dB in SFDR vs. the theoretical value for an interferometric modulator without feedback was achieved....

  16. Augmenting Future In-Vehicle Interactions With Remote Tactile Feedback

    E-Print Network [OSTI]

    . Nowadays, also many controllers for in-vehicle information systems such as BMW's iDrive1 are equipped of tactile stimuli could help here. 1 www.bmw.com AutoUI`11, Workshop on Natural User Interfaces, 30th environment. Similar to direct tactile stimuli, the remote application of feedback on touch surfaces has

  17. PPPL-3242 -Preprint: March 1997, UC-427 TSC Simulation of Feedback Stabilization of

    E-Print Network [OSTI]

    of the equilibrium shaping coils. The feedback electrical currents in these coils are driven by applying a voltage

  18. Status Report on the Modeling of TRISO Energy Deposition, Time-Dependent Temperature Field and Doppler Feedback

    SciTech Connect (OSTI)

    Javier Ortensi; Abderrafi M Ougouag

    2009-07-01T23:59:59.000Z

    The Doppler feedback mechanism is a major contributor to the passive safety of gas-cooled, graphite-moderated high temperature reactors that use fuel based on Tristructural-Isotropic coated particles. It follows that the correct prediction of the magnitude and time-dependence of this feedback effect is essential to the conduct of safety analyses for these reactors. We present a fuel conduction model for obtaining better estimates of the temperature feedback during moderate and fast transients. The fuel model has been incorporated in the CYNOD-THERMIX-KONVEK suite of coupled codes as a single TRISO particle within each calculation cell. The heat generation rate is scaled down from the neutronic solution and a Dirichlet boundary condition is imposed as the bulk graphite temperature from the thermal-hydraulic solution. This simplified approach yields similar results to those obtained with more complex methods, requiring multi-TRISO calculations within one control volume, but with much less computational effort. We provide an analysis of the hypothetical total control ejection event in the PBMR-400 design that clearly depicts the improvement in the predictions of the fuel temperature.

  19. The dipole corrector magnets for the RHIC fast global orbit feedback system

    SciTech Connect (OSTI)

    Thieberger, P.; Arnold, L.; Folz, C.; Hulsart, R.; Jain, A.; Karl, R.; Mahler, G.; Meng, W.; Mernick, K.; Michnoff, R.; Minty, M.; Montag, C.; Ptitsyn, V.; Ritter, J.; Smart, L.; Tuozzolo, J.; White, J.

    2011-03-28T23:59:59.000Z

    The recently completed RHIC fast global orbit feedback system uses 24 small 'window-frame' horizontal dipole correctors. Space limitations dictated a very compact design. The magnetic design and modelling of these laminated yoke magnets is described as well as the mechanical implementation, coil winding, vacuum impregnation, etc. Test procedures to determine the field quality and frequency response are described. The results of these measurements are presented and discussed. A small fringe field from each magnet, overlapping the opposite RHIC ring, is compensated by a correction winding placed on the opposite ring's magnet and connected in series with the main winding of the first one. Results from measurements of this compensation scheme are shown and discussed.

  20. Modeling laser-induced periodic surface structures: Finite-difference time-domain feedback simulations

    SciTech Connect (OSTI)

    Skolski, J. Z. P., E-mail: j.z.p.skolski@utwente.nl; Vincenc Obona, J. [Materials innovation institute M2i, Faculty of Engineering Technology, Chair of Applied Laser Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); Römer, G. R. B. E.; Huis in 't Veld, A. J. [Faculty of Engineering Technology, Chair of Applied Laser Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

    2014-03-14T23:59:59.000Z

    A model predicting the formation of laser-induced periodic surface structures (LIPSSs) is presented. That is, the finite-difference time domain method is used to study the interaction of electromagnetic fields with rough surfaces. In this approach, the rough surface is modified by “ablation after each laser pulse,” according to the absorbed energy profile, in order to account for inter-pulse feedback mechanisms. LIPSSs with a periodicity significantly smaller than the laser wavelength are found to “grow” either parallel or orthogonal to the laser polarization. The change in orientation and periodicity follow from the model. LIPSSs with a periodicity larger than the wavelength of the laser radiation and complex superimposed LIPSS patterns are also predicted by the model.

  1. Absence of jamming in ant trails: Feedback control of self propulsion and noise

    E-Print Network [OSTI]

    Chaudhuri, Debasish

    2014-01-01T23:59:59.000Z

    We present a model of ant traffic considering individual ants as self-propelled particles undergoing single file motion on a one-dimensional trail. Recent experiments on unidirectional ant traffic in well-formed natural trails showed that the collective velocity of ants remains approximately unchanged, leading to absence of jamming even at very high densities [ John et. al., Phys. Rev. Lett. 102, 108001 (2009) ]. Assuming a feedback control mechanism of self-propulsion force generated by each ant using information about the distance from the ant in front, our model captures all the main features observed in the experiment. The distance headway distribution shows a maximum corresponding to separations within clusters. The position of this maximum remains independent of average number density. We find a non-equilibrium first order transition, with the formation of an infinite cluster at a threshold density where all the ants in the system suddenly become part of a single cluster.

  2. RESEARCH Open Access The role of feed-forward and feedback processes

    E-Print Network [OSTI]

    Vijayakumar, Sethu

    to amputees. Artificial feedback systems can exploit the idea of sen- sory substitution: feedback delivered with a closed-loop robotic hand and instructed to grasp and lift objects of different weights as we recorded the cognitive processes underlying grasping and lifting. We have shown quantitatively that tactile feedback can

  3. Monolithic amplifier with stable, high resistance feedback element and method for fabricating the same

    DOE Patents [OSTI]

    O'Connor, Paul (Bellport, NY)

    1998-08-11T23:59:59.000Z

    A monolithic amplifier includes a stable, high resistance feedback circuit and a dynamic bias circuit. The dynamic bias circuit is formed with active elements matched to those in the amplifier and feedback circuit to compensate for variations in the operating and threshold voltages thereby maintaining a stable resistance in the feedback circuit.

  4. Joint Power Control and Beamforming Codebook Design for MISO Channels with Limited Feedback

    E-Print Network [OSTI]

    Yu, Wei

    Joint Power Control and Beamforming Codebook Design for MISO Channels with Limited Feedback Behrouz-input single-output (MISO) wireless systems with a rate-limited feedback link. The problem is cast in the form-output (MISO) channel with channel state information at the receiver (CSIR) and a noiseless delay-free feedback

  5. Controller design issues in the feedback control of radio frequency plasma processing reactors

    E-Print Network [OSTI]

    Kushner, Mark

    Controller design issues in the feedback control of radio frequency plasma processing reactors feedback control of inductively coupled plasma processing reactors for polysilicon etching and be successfully used for feedback control of plasma processing reactors.4 There are many control strate- gies

  6. Monolithic amplifier with stable, high resistance feedback element and method for fabricating the same

    DOE Patents [OSTI]

    O`Connor, P.

    1998-08-11T23:59:59.000Z

    A monolithic amplifier includes a stable, high resistance feedback circuit and a dynamic bias circuit. The dynamic bias circuit is formed with active elements matched to those in the amplifier and feedback circuit to compensate for variations in the operating and threshold voltages thereby maintaining a stable resistance in the feedback circuit. 11 figs.

  7. Mitigation of resource competition in synthetic genetic circuits through feedback regulation

    E-Print Network [OSTI]

    Del Vecchio, Domitilla

    Mitigation of resource competition in synthetic genetic circuits through feedback regulation expression. In particular, we analyze and compare the ability of several inhibitory feedback regulation that arise in synthetic biology. Questions of how feedback regulation may be employed by biochemical systems

  8. Novel feedback and signalling mechanisms for interference management and efficient modulation 

    E-Print Network [OSTI]

    Abu-alhiga, Rami

    2010-01-01T23:59:59.000Z

    In order to meet the ever-growing demand for mobile data, a number of different technologies have been adopted by the fourth generation standardization bodies. These include multiple access schemes such as spatial division ...

  9. Reputation, Trust, & Rebates: How Online Markets Can Improve Their Feedback Mechanisms

    E-Print Network [OSTI]

    Li, Lingfang Ivy

    2006-01-01T23:59:59.000Z

    Economics, forthcoming. D. G. Saari. Explaining all three-of Economic Theory, 87: D. G. Saari. Chaotic Elections! Aat Voting. 2001. D. G. Saari and K. K. Sieberg. The sum of

  10. CONTROL OF PYRIMIDINE BIOSYNTHESIS IN ESCHERICHIA COLI BY A FEED-BACK MECHANISM*

    E-Print Network [OSTI]

    Bulyk, Martha L.

    inches below three Westinghouse sterile lamps No. WL-782L-30. Under the conditions used, both DNA and RNA, 1954. Supported, in part, by research grants from the Lederle Laboratories Division, American Cyanamid

  11. Enhanced Energy-Aware Feedback Scheduling of Embedded Control Systems

    E-Print Network [OSTI]

    Xia, Feng; Zhao, Wenhong; Sun, Youxian; Dong, Jinxiang

    2008-01-01T23:59:59.000Z

    Dynamic voltage scaling (DVS) is one of the most effective techniques for reducing energy consumption in embedded and real-time systems. However, traditional DVS algorithms have inherent limitations on their capability in energy saving since they rarely take into account the actual application requirements and often exploit fixed timing constraints of real-time tasks. Taking advantage of application adaptation, an enhanced energy-aware feedback scheduling (EEAFS) scheme is proposed, which integrates feedback scheduling with DVS. To achieve further reduction in energy consumption over pure DVS while not jeopardizing the quality of control, the sampling period of each control loop is adapted to its actual control performance, thus exploring flexible timing constraints on control tasks. Extensive simulation results are given to demonstrate the effectiveness of EEAFS under different scenarios. Compared with the optimal pure DVS scheme, EEAFS saves much more energy while yielding comparable control performance.

  12. Experimental control of chaos by variable and distributed delay feedback

    E-Print Network [OSTI]

    Thomas Jüngling; Aleksandar Gjurchinovski; Viktor Urumov

    2012-02-02T23:59:59.000Z

    We report on a significant improvement of the classical time-delayed feedback control method for stabilization of unstable periodic orbits or steady states. In an electronic circuit experiment we were able to realize time-varying and distributed delays in the control force leading to successful control for large parameter sets including large time delays. The presented technique makes advanced use of the natural torsion of the orbits, which is also necessary for the original control method to work.

  13. The pointer basis and the feedback stabilization of quantum systems

    E-Print Network [OSTI]

    L. Li; A. Chia; H. M. Wiseman

    2014-11-19T23:59:59.000Z

    The dynamics for an open quantum system can be `unravelled' in infinitely many ways, depending on how the environment is monitored, yielding different sorts of conditioned states, evolving stochastically. In the case of ideal monitoring these states are pure, and the set of states for a given monitoring forms a basis (which is overcomplete in general) for the system. It has been argued elsewhere [D. Atkins et al., Europhys. Lett. 69, 163 (2005)] that the `pointer basis' as introduced by Zurek and Paz [Phys. Rev. Lett 70, 1187(1993)], should be identified with the unravelling-induced basis which decoheres most slowly. Here we show the applicability of this concept of pointer basis to the problem of state stabilization for quantum systems. In particular we prove that for linear Gaussian quantum systems, if the feedback control is assumed to be strong compared to the decoherence of the pointer basis, then the system can be stabilized in one of the pointer basis states with a fidelity close to one (the infidelity varies inversely with the control strength). Moreover, if the aim of the feedback is to maximize the fidelity of the unconditioned system state with a pure state that is one of its conditioned states, then the optimal unravelling for stabilizing the system in this way is that which induces the pointer basis for the conditioned states. We illustrate these results with a model system: quantum Brownian motion. We show that even if the feedback control strength is comparable to the decoherence, the optimal unravelling still induces a basis very close to the pointer basis. However if the feedback control is weak compared to the decoherence, this is not the case.

  14. Feedback-Controlled LED Photobioreactor for Photophysiological Studies of Cyanobacteria

    SciTech Connect (OSTI)

    Melnicki, Matthew R.; Pinchuk, Grigoriy E.; Hill, Eric A.; Kucek, Leo A.; Stolyar, Sergey; Fredrickson, Jim K.; Konopka, Allan; Beliaev, Alex S.

    2013-04-09T23:59:59.000Z

    A custom photobioreactor (PBR) was designed to enable automatic light adjustments using computerized feedback control. A black anodized aluminum enclosure, constructed to surround the borosilicate reactor vessel, prevents the transmission of ambient light and serves as a mount for arrays of light-emitting diodes (LEDs). The high-output LEDs provide narrow-band light of either 630 or 680 nm for preferential excitation of the cyanobacterial light-harvesting pigments, phycobilin or chlorophyll a, respectively. Custom developed software BioLume provides automatic control of optical properties and a computer feedback loop can automatically adjust the incident irradiance as necessary to maintain a fixed transmitted light through the culture, based on user-determined set points. This feedback control serves to compensate for culture dynamics which have optical effects, (e.g., changing cell density, pigment adaptations) and thus can determine the appropriate light conditions for physiological comparisons or to cultivate light-sensitive strains, without prior analyses. The LED PBR may also be controlled as a turbidostat, using a feedback loop to continuously adjust the rate of media-dilution based on the transmitted light measurements, with a fast and precise response. This cultivation system gains further merit as a high-performance analytical device, using non-invasive tools (e.g., dissolved gas sensors, online mass spectrometry) to automate real-time measurements, thus permitting unsupervised experiments to search for optimal growth conditions, to monitor physiological responses to perturbations, as well as to quantitate photophysiological parameters using an in situ light-saturation response routine.

  15. Single electron beam rf feedback free electron laser

    DOE Patents [OSTI]

    Brau, C.A.; Stein, W.E.; Rockwood, S.D.

    1981-02-11T23:59:59.000Z

    A free electron laser system and electron beam system for a free electron laser which uses rf feedback to enhance efficiency are described. Rf energy is extracted from a single electron beam by decelerating cavities and energy is returned to accelerating cavities using rf returns, such as rf waveguides, rf feedthroughs, resonant feedthroughs, etc. This rf energy is added to rf klystron energy to reduce the required input energy and thereby enhance energy efficiency of the system.

  16. The Radiative Feedback of the First Cosmological Objects

    E-Print Network [OSTI]

    Zoltan Haiman; Tom Abel; Martin J. Rees

    1999-03-23T23:59:59.000Z

    In hierarchical models of structure formation, an early cosmic UV background (UVB) is produced by the small (T_vir 10^4 K) collapse. If the small halos host mini-quasars with hard spectra extending to approximately 1 keV, then their X-rays balance the effects of the UVB, the negative feedback does not occur, and reionization can be caused by the small halos.

  17. Moment Closure Approximations in a Genetic Negative Feedback Circuit

    E-Print Network [OSTI]

    Mohammad Soltani; Cesar Vargas; Niraj Kumar; Rahul Kulkarni; Abhyudai Singh

    2014-05-15T23:59:59.000Z

    Auto-regulation, a process wherein a protein negatively regulates its own production, is a common motif in gene expression networks. Negative feedback in gene expression plays a critical role in buffering intracellular fluctuations in protein concentrations around optimal value. Due to the nonlinearities present in these feedbacks, moment dynamics are typically not closed, in the sense that the time derivative of the lower-order statistical moments of the protein copy number depends on high-order moments. Moment equations are closed by expressing higher-order moments as nonlinear functions of lower-order moments, a technique commonly referred to as moment closure. Here, we compare the performance of different moment closure techniques. Our results show that the commonly used closure method, which assumes a priori that the protein population counts are normally distributed, performs poorly. In contrast, conditional derivative matching, a novel closure scheme proposed here provides a good approximation to the exact moments across different parameter regimes. In summary our study provides a new moment closure method for studying stochastic dynamics of genetic negative feedback circuits, and can be extended to probe noise in more complex gene networks.

  18. Coherence-enhanced efficiency of feedback-driven quantum engines

    E-Print Network [OSTI]

    Kay Brandner; Michael Bauer; Michael T. Schmid; Udo Seifert

    2015-03-16T23:59:59.000Z

    A genuine feature of projective quantum measurements is that they inevitably alter the mean energy of the observed system if the measured quantity does not commute with the Hamiltonian. Compared to the classical case, Jacobs proved that this additional energetic cost leads to a stronger bound on the work extractable after a single measurement from a system initially in thermal equilibrium [Phys. Rev. A 80, 012322 (2009)]. Here, we extend this bound to a large class of feedback-driven quantum engines operating periodically and in finite time. The bound thus implies a natural definition for the efficiency of information to work conversion in such devices. For a simple model consisting of a laser-driven two-level system, we maximize the efficiency with respect to the observable whose measurement is used to control the feedback operations. We find that the optimal observable typically does not commute with the Hamiltonian and hence would not be available in a classical two level system. This result reveals that periodic feedback engines operating in the quantum realm can exploit quantum coherences to enhance efficiency.

  19. The Impact of Galactic Feedback on the Circumgalactic Medium

    E-Print Network [OSTI]

    Suresh, Joshua; Vogelsberger, Mark; Genel, Shy; Torrey, Paul; Sijacki, Debora; Springel, Volker; Hernquist, Lars

    2015-01-01T23:59:59.000Z

    Galactic feedback strongly affects the way galactic environments are enriched. We examine this connection by performing a suite of cosmological hydrodynamic simulations, exploring a range of parameters based on the galaxy formation model developed in Vogelsberger et al. 2013 (henceforth V13). We examine the effects of AGN feedback, wind mass loading, wind specific energy, and wind metal-loading on the properties of the circumgalactic medium (CGM) of galaxies with $M_\\text{halo} > 10^{11} M_\\odot$. Note that while the V13 model was tuned to match observations including the stellar mass function, no explicit tuning was done for the CGM. The wind energy per unit outflow mass has the most significant effect on the CGM enrichment. High energy winds launch metals far beyond the virial radius. AGN feedback also has a significant effect, but only at $z < 3$. We compare to high redshift HI and CIV observations. All our simulations produce the observed number of Damped Lyman-$\\alpha$ Absorbers. At lower column densi...

  20. FEEDBACK EFFECTS ON LOW-MASS STAR FORMATION

    SciTech Connect (OSTI)

    Hansen, Charles E.; Klein, Richard I.; McKee, Christopher F. [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Fisher, Robert T. [Physics Department, University of Massachusetts, Dartmouth, MA (United States)

    2012-03-01T23:59:59.000Z

    Protostellar feedback, both radiation and bipolar outflows, dramatically affects the fragmentation and mass accretion from star-forming cores. We use ORION, an adaptive mesh refinement gravito-radiation-hydrodynamics code, to simulate low-mass star formation in a turbulent molecular cloud in the presence of protostellar feedback. We present results of the first simulations of a star-forming cluster that include both radiative transfer and protostellar outflows. We run four simulations to isolate the individual effects of radiation feedback and outflow feedback as well as the combination of the two. We find that outflows reduce protostellar masses and accretion rates each by a factor of three and therefore reduce protostellar luminosities by an order of magnitude. This means that, while radiation feedback suppresses fragmentation, outflows render protostellar radiation largely irrelevant for low-mass star formation above a mass scale of 0.05 M{sub Sun }. We find initial fragmentation of our cloud at half the global Jeans length, around 0.1 pc. With insufficient protostellar radiation to stop it, these 0.1 pc cores fragment repeatedly, forming typically 10 stars each. The accretion rate in these stars scales with mass as predicted from core accretion models that include both thermal and turbulent motions; the accretion rate does not appear to be consistent with either competitive accretion or accretion from an isothermal sphere. We find that protostellar outflows do not significantly affect the overall cloud dynamics, in the absence of magnetic fields, due to their small opening angles and poor coupling to the dense gas. The outflows reduce the mass from the cores by 2/3, giving a core to star efficiency, {epsilon}{sub core} {approx_equal} 1/3. The simulations are also able to reproduce many observation of local star-forming regions. Our simulation with radiation and outflows reproduces the observed protostellar luminosity function. All of the simulations can reproduce observed core mass functions, though we find they are sensitive to telescope resolution. We also reproduce the two-point correlation function of these observed cores. Lastly, we reproduce the initial mass function itself, including the low-mass end, when outflows are included.

  1. Basal-subtype and MEK-Pl3K feedback signaling determine susceptibility of breast cancer cells to MEK inhibition

    SciTech Connect (OSTI)

    Mirzoeva, Olga K.; Das, Debopriya; Heiser, Laura M.; Bhattacharya, Sanchita; Siwak, Doris; Gendelman, Rina; Bayani, Nora; Wang, Nicholas J.; Neve, Richard M.; Knight, Zachary; Feiler, Heidi S.; Gascard, Philippe; Parvin, Bahram; Spellman, Paul T.; Shokat, Kevan M.; Wyrobek, Andrew J.; Bissell, Mina J.; McCormick, Frank; Kuo, Wen-Lin; Mills, Gordon B.; Gray, Joe W.; Korn, W. Michael

    2009-01-23T23:59:59.000Z

    Specific inhibitors of MEK have been developed that efficiently inhibit the oncogenic RAF-MEK-ERK pathway. We employed a systems-based approach to identify breast cancer subtypes particularly susceptible to MEK inhibitors and to understand molecular mechanisms conferring resistance to such compounds. Basal-type breast cancer cells were found to be particularly susceptible to growth-inhibition by small-molecule MEK inhibitors. Activation of the PI3 kinase pathway in response to MEK inhibition through a negative MEK-EGFR-PI3 kinase feedback loop was found to limit efficacy. Interruption of this feedback mechanism by targeting MEK and PI3 kinase produced synergistic effects, including induction of apoptosis and, in some cell lines, cell cycle arrest and protection from apoptosis induced by proapoptotic agents. These findings enhance our understanding of the interconnectivity of oncogenic signal transduction circuits and have implications for the design of future clinical trials of MEK inhibitors in breast cancer by guiding patient selection and suggesting rational combination therapies.

  2. Essays in Macroeconomics and Finance

    E-Print Network [OSTI]

    Khramov, Vadim

    2013-01-01T23:59:59.000Z

    economies. ” Journal of Finance 39, pages 77-92. Vasicek,Interest Rate. ” Journal of Finance, Vol. 47, No. 3 Chernov,of Economics. B.A. (Finance), Higher School of Economics.

  3. Essays on Open Economy Macroeconomics

    E-Print Network [OSTI]

    Lu, Mi

    2013-01-01T23:59:59.000Z

    Hong Kong Household House Preference Shock . . . . . PPPnominal depreciation rate (or PPP relationship) is ˆ t+1 ? U1 + ? ?,t Where ? ?,t is PPP shock. PPP shock is very common

  4. Essays on Macroeconomics and Oil

    E-Print Network [OSTI]

    CAKIR, NIDA

    2013-01-01T23:59:59.000Z

    Venezuelan Oil Industry Total Wells Drilled and InvestmentWells Drilled and Investment in the Venezuelan Oil Industryopenness of the oil sector to foreign investment contributes

  5. Essays on Macroeconomics and Oil

    E-Print Network [OSTI]

    CAKIR, NIDA

    2013-01-01T23:59:59.000Z

    reserves. In the data, crude oil reserve addi- tions consistForce and Proven Reserves in the Venezuelan Oil Industry .such as crude oil production, proved reserves, new reserves,

  6. Essays in macroeconomics and finance

    E-Print Network [OSTI]

    Mohsenzadeh Kermani, Amir Reza

    2013-01-01T23:59:59.000Z

    The first chapter proposes a model of booms and busts in housing and non-housing consumption driven by the interplay between relatively low interest rates and an expansion of credit, triggered by further decline in interest ...

  7. Essays on Macroeconomics and Oil

    E-Print Network [OSTI]

    CAKIR, NIDA

    2013-01-01T23:59:59.000Z

    is described below. Data Crude oil production data is fromproductivity measure is crude oil production per worker, andwhich is measured as crude oil production per worker, is

  8. Essays on finance and macroeconomics

    E-Print Network [OSTI]

    Di Tella, Sebastian T. (Sebastian Tariacuri)

    2013-01-01T23:59:59.000Z

    This thesis studies the role of the financial system in the amplification and propagation of business cycles. Chapter 1 studies the origin and propagation of balance sheet recessions. I first show that in standard models ...

  9. Essays on macroeconomics and forecasting

    E-Print Network [OSTI]

    Liu, Dandan

    2006-10-30T23:59:59.000Z

    is the structural factor augmented vector autoregressive (SFAVAR) model and the other is the structural factor vector autoregressive (SFVAR) model. Compared to the traditional vector autogression (VAR) model, both models incorporate far more information from...

  10. Essays in Macroeconomics and Finance

    E-Print Network [OSTI]

    Khramov, Vadim

    2013-01-01T23:59:59.000Z

    3, 14, pages 325–332. Huizinga, John and Frederic Mishkin,variables (Mishkin (1981) and Huizinga and Mishkin (1986)).

  11. Essays on Macroeconomics and Oil

    E-Print Network [OSTI]

    CAKIR, NIDA

    2013-01-01T23:59:59.000Z

    Oil Production in Venezuela and Mexico . . . . . . . . . .Oil Production and Productivity in Venezuela and Mexico . . . . . . . .2.6: Oil Production in Venezuela and Mexico 350 Productivity

  12. Essays on Macroeconomics and Oil

    E-Print Network [OSTI]

    CAKIR, NIDA

    2013-01-01T23:59:59.000Z

    the Oil Industry . . . . . . . . . . . . . . . . . . . . . .in the Venezuelan Oil Industry . . . . . . . . . . . . .and Productivity: Evidence from the Oil Industry . .

  13. Essays on Macroeconomics and Oil

    E-Print Network [OSTI]

    CAKIR, NIDA

    2013-01-01T23:59:59.000Z

    Oil Production . . . . . . . . . . . . . . . . . . . . . . . . . . .Oil Production in Venezuela and Mexico . . . . . . . . . .Oil Production and Productivity in Venezuela and

  14. Say's Law and modern macroeconomics

    E-Print Network [OSTI]

    Van Allen, Laurel Cameron

    2013-02-22T23:59:59.000Z

    Many economists have debated the interpretation of what is known as "Say's Law of markets"; it has been the subject of controversy for two centuries. Jean Baptiste Say describes Say's Law by noting that the "success of one branch of commerce...

  15. Harvesting entropy and quantifying the transition from noise to chaos in a photon-counting feedback loop

    E-Print Network [OSTI]

    Aaron M. Hagerstrom; Thomas E. Murphy; Rajarshi Roy

    2015-03-27T23:59:59.000Z

    Some physical processes, including the intensity fluctuations of a chaotic laser, the detection of single photons, and the Brownian motion of a microscopic particle in a fluid are unpredictable, at least on long timescales. This unpredictability can be due to a variety of physical mechanisms, but it is quantified by an entropy rate. This rate describes how quickly a system produces new and random information, is fundamentally important in statistical mechanics and practically important for random number generation. We experimentally study entropy generation and the emergence of deterministic chaotic dynamics from discrete noise in a system that applies feedback to a weak optical signal at the single-photon level. We show that the dynamics qualitatively change from shot noise to chaos as the photon rate increases, and that the entropy rate can reflect either the deterministic or noisy aspects of the system depending on the sampling rate and resolution.

  16. Temperature feedback control for long-term carrier-envelope phase locking

    DOE Patents [OSTI]

    Chang, Zenghu (Manhattan, KS); Yun, Chenxia (Manhattan, KS); Chen, Shouyuan (Manhattan, KS); Wang, He (Manhattan, KS); Chini, Michael (Manhattan, KS)

    2012-07-24T23:59:59.000Z

    A feedback control module for stabilizing a carrier-envelope phase of an output of a laser oscillator system comprises a first photodetector, a second photodetector, a phase stabilizer, an optical modulator, and a thermal control element. The first photodetector may generate a first feedback signal corresponding to a first portion of a laser beam from an oscillator. The second photodetector may generate a second feedback signal corresponding to a second portion of the laser beam filtered by a low-pass filter. The phase stabilizer may divide the frequency of the first feedback signal by a factor and generate an error signal corresponding to the difference between the frequency-divided first feedback signal and the second feedback signal. The optical modulator may modulate the laser beam within the oscillator corresponding to the error signal. The thermal control unit may change the temperature of the oscillator corresponding to a signal operable to control the optical modulator.

  17. Robust quantum parameter estimation: Coherent magnetometry with feedback

    SciTech Connect (OSTI)

    Stockton, John K.; Geremia, J.M.; Doherty, Andrew C.; Mabuchi, Hideo [Norman Bridge Laboratory of Physics, Mail Code 12-33, California Institute of Technology, Pasadena, California 91125 (United States)

    2004-03-01T23:59:59.000Z

    We describe the formalism for optimally estimating and controlling both the state of a spin ensemble and a scalar magnetic field with information obtained from a continuous quantum limited measurement of the spin precession due to the field. The full quantum parameter estimation model is reduced to a simplified equivalent representation to which classical estimation and control theory is applied. We consider both the tracking of static and fluctuating fields in the transient and steady-state regimes. By using feedback control, the field estimation can be made robust to uncertainty about the total spin number.

  18. On Optimal Feedback Control for Stationary Linear Systems

    SciTech Connect (OSTI)

    Russell, David L., E-mail: russell@math.vt.ed [Virginia Tech, Department of Mathematics (United States)

    2010-04-15T23:59:59.000Z

    We study linear-quadratic optimal control problems for finite dimensional stationary linear systems AX+BU=Z with output Y=CX+DU from the viewpoint of linear feedback solution. We interpret solutions in relation to system robustness with respect to disturbances Z and relate them to nonlinear matrix equations of Riccati type and eigenvalue-eigenvector problems for the corresponding Hamiltonian system. Examples are included along with an indication of extensions to continuous, i.e., infinite dimensional, systems, primarily of elliptic type.

  19. Weak Measurement and Feedback in Superconducting Quantum Circuits

    E-Print Network [OSTI]

    K. W. Murch; R. Vijay; I. Siddiqi

    2015-07-16T23:59:59.000Z

    We describe the implementation of weak quantum measurements in superconducting qubits, focusing specifically on transmon type devices in the circuit quantum electrodynamics architecture. To access this regime, the readout cavity is probed with on average a single microwave photon. Such low-level signals are detected using near quantum-noise-limited superconducting parametric amplifiers. Weak measurements yield partial information about the quantum state, and correspondingly do not completely project the qubit into an eigenstate. As such, we use the measurement record to either sequentially reconstruct the quantum state at a given time, yielding a quantum trajectory, or to close a direct quantum feedback loop, stabilizing Rabi oscillations indefinitely.

  20. Self-Excitation and Feedback Cooling of an Isolated Proton

    SciTech Connect (OSTI)

    Guise, N.; DiSciacca, J.; Gabrielse, G. [Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States)

    2010-04-09T23:59:59.000Z

    The first one-proton self-excited oscillator (SEO) and one-proton feedback cooling are demonstrated. In a Penning trap with a large magnetic gradient, the SEO frequency is resolved to the high precision needed to detect a one-proton spin flip. This is after undamped magnetron motion is sideband cooled to a 14 mK theoretical limit, and despite random frequency shifts (typically larger than those from a spin flip) that take place every time sideband cooling is applied. The observations open a possible path towards a million-fold improved comparison of the p and p magnetic moments.

  1. Ignition feedback regenerative free electron laser (FEL) amplifier

    DOE Patents [OSTI]

    Kim, Kwang-Je (Burr Ridge, IL); Zholents, Alexander (Walnut Creek, CA); Zolotorev, Max (Oakland, CA)

    2001-01-01T23:59:59.000Z

    An ignition feedback regenerative amplifier consists of an injector, a linear accelerator with energy recovery, and a high-gain free electron laser amplifier. A fraction of the free electron laser output is coupled to the input to operate the free electron laser in the regenerative mode. A mode filter in this loop prevents run away instability. Another fraction of the output, after suitable frequency up conversion, is used to drive the photocathode. An external laser is provided to start up both the amplifier and the injector, thus igniting the system.

  2. Fiber optic sensor: Feedback control design and implementation

    SciTech Connect (OSTI)

    Tung, D.; Bertram, L.; Hillaire, R.; Anderson, S.; Leonard, S.; Marburger, S.

    1997-07-01T23:59:59.000Z

    Digital feedback control of Gas Tungsten Arc Welding (GTAW) has been demonstrated on a tube sample of stainless steel and titanium alloy. A fiber optic sensor returns a signal proportional to backside radiance from the workpiece; that signal is used by the controller to compute a compensation weld current. The controller executes 10 times a second on an Intel 486 chip. For travel speeds of 3 to 6 inches per minute and thicknesses between 0.025 and 0.10 inches, constant backside bead width was maintained within 0.02 inches, from startup to tie-in.

  3. Contractor Rating and Feedback Systems | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page onYouTube YouTube Note: Since the YouTube platformBuildingCoalComplex(GC-72) | DepartmentEnergy8Rating and Feedback

  4. Carbon Credit Capital and Feedback Ventures JV | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand Jump to:EzfeedflagBiomassSustainableCSL GasPermits ManualCanisteo,Verde:ConnectionsUtah:Feedback

  5. Fermilab | Fermilab at Work | Web Form | Feedback Form

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC) Environmental Assessments (EA)Budget » FYU.S. DOEFigureTip ofThe EAGFermilabFeedback

  6. Computational mechanics

    SciTech Connect (OSTI)

    Goudreau, G.L.

    1993-03-01T23:59:59.000Z

    The Computational Mechanics thrust area sponsors research into the underlying solid, structural and fluid mechanics and heat transfer necessary for the development of state-of-the-art general purpose computational software. The scale of computational capability spans office workstations, departmental computer servers, and Cray-class supercomputers. The DYNA, NIKE, and TOPAZ codes have achieved world fame through our broad collaborators program, in addition to their strong support of on-going Lawrence Livermore National Laboratory (LLNL) programs. Several technology transfer initiatives have been based on these established codes, teaming LLNL analysts and researchers with counterparts in industry, extending code capability to specific industrial interests of casting, metalforming, and automobile crash dynamics. The next-generation solid/structural mechanics code, ParaDyn, is targeted toward massively parallel computers, which will extend performance from gigaflop to teraflop power. Our work for FY-92 is described in the following eight articles: (1) Solution Strategies: New Approaches for Strongly Nonlinear Quasistatic Problems Using DYNA3D; (2) Enhanced Enforcement of Mechanical Contact: The Method of Augmented Lagrangians; (3) ParaDyn: New Generation Solid/Structural Mechanics Codes for Massively Parallel Processors; (4) Composite Damage Modeling; (5) HYDRA: A Parallel/Vector Flow Solver for Three-Dimensional, Transient, Incompressible Viscous How; (6) Development and Testing of the TRIM3D Radiation Heat Transfer Code; (7) A Methodology for Calculating the Seismic Response of Critical Structures; and (8) Reinforced Concrete Damage Modeling.

  7. Quantum feedback cooling of a single trapped ion in front of a mirror

    E-Print Network [OSTI]

    V. Steixner; P. Rabl; P. Zoller

    2005-06-22T23:59:59.000Z

    We develop a theory of quantum feedback cooling of a single ion trapped in front of a mirror. By monitoring the motional sidebands of the light emitted into the mirror mode we infer the position of the ion, and act back with an appropriate force to cool the ion. We derive a feedback master equation along the lines of the quantum feedback theory developed by Wiseman and Milburn, which provides us with cooling times and final temperatures as a function of feedback gain and various system parameters.

  8. On-Board Measurement of Ammonia and Nitrous Oxide Using Feedback...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Board Measurement of Ammonia and Nitrous Oxide Using Feedback Absorption Laser Spectroscopy Combined with Amplified Resonance and Low Pressure Sampling On-Board Measurement of...

  9. Feedback, power control, and beamforming : methods for situational aware wireless networks

    E-Print Network [OSTI]

    Huang, Yichao

    2012-01-01T23:59:59.000Z

    Outage balancing in multiuser MISO networks: network dualityOutage balancing in multiuser MISO networks: network dualitywith partial feedback for MISO downlink transmission using

  10. A High-Fidelity Energy Monitoring and Feedback Architecture for Reducing Electrical Consumption in Buildings

    E-Print Network [OSTI]

    Jiang, Xiaofan

    2010-01-01T23:59:59.000Z

    Idle Laptop Figure 9.4: Aggregated energy usage by applianceenergy usage based on the appliance types, such CHAPTER 8. FEEDBACK as “desktops”, “laptops”, “

  11. An Investigation into the Benefits of Tactile Feedback for Laparoscopic, Robotic, and Remote Surgery

    E-Print Network [OSTI]

    Wottawa, Christopher Robert

    2013-01-01T23:59:59.000Z

    Remote Surgery System with Integrated Tactile Feedback The primary difficulty in using the LapaRobot was the occurrence of power and heating

  12. A model for improving microbial biofuel production using a synthetic feedback loop

    E-Print Network [OSTI]

    Dunlop, Mary J.; Keasling, Jay D.; Mukhopadhyay, Aindrila

    2010-01-01T23:59:59.000Z

    potential for great impact. Biofuels are a promising form ofbe engineered to produce biofuels, the fuels are often toxicKeywords Feedback control Á Biofuels Á Biological control

  13. An Investigation into the Benefits of Tactile Feedback for Laparoscopic, Robotic, and Remote Surgery

    E-Print Network [OSTI]

    Wottawa, Christopher Robert

    2013-01-01T23:59:59.000Z

    to haptic feedback in robotic surgery. (March 2010 NSFfeedback actuator array for robotic surgery or simulation.conventional versus robotic approach—a comparative study.

  14. adrenaline-mediated positive feedback: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of galaxy evolution to form massive galaxies compatible with observations. I will present some of our recent results and will put them into further context of other feedback...

  15. Computational mechanics

    SciTech Connect (OSTI)

    Raboin, P J

    1998-01-01T23:59:59.000Z

    The Computational Mechanics thrust area is a vital and growing facet of the Mechanical Engineering Department at Lawrence Livermore National Laboratory (LLNL). This work supports the development of computational analysis tools in the areas of structural mechanics and heat transfer. Over 75 analysts depend on thrust area-supported software running on a variety of computing platforms to meet the demands of LLNL programs. Interactions with the Department of Defense (DOD) High Performance Computing and Modernization Program and the Defense Special Weapons Agency are of special importance as they support our ParaDyn project in its development of new parallel capabilities for DYNA3D. Working with DOD customers has been invaluable to driving this technology in directions mutually beneficial to the Department of Energy. Other projects associated with the Computational Mechanics thrust area include work with the Partnership for a New Generation Vehicle (PNGV) for ''Springback Predictability'' and with the Federal Aviation Administration (FAA) for the ''Development of Methodologies for Evaluating Containment and Mitigation of Uncontained Engine Debris.'' In this report for FY-97, there are five articles detailing three code development activities and two projects that synthesized new code capabilities with new analytic research in damage/failure and biomechanics. The article this year are: (1) Energy- and Momentum-Conserving Rigid-Body Contact for NIKE3D and DYNA3D; (2) Computational Modeling of Prosthetics: A New Approach to Implant Design; (3) Characterization of Laser-Induced Mechanical Failure Damage of Optical Components; (4) Parallel Algorithm Research for Solid Mechanics Applications Using Finite Element Analysis; and (5) An Accurate One-Step Elasto-Plasticity Algorithm for Shell Elements in DYNA3D.

  16. Supernova Sweeping and Black-Hole Feedback in Elliptical Galaxies

    E-Print Network [OSTI]

    Voit, G M; O'Shea, B W; Bryan, G L; Sun, M; Werner, N

    2015-01-01T23:59:59.000Z

    Most of the massive elliptical galaxies in the universe stopped forming stars billions of years ago, even though plenty of hot gas remains available for star formation. Here we present compelling evidence indicating that quenching of star formation depends on both black-hole feedback and Type Ia supernova heating. We analyze Chandra X-ray observations of ten massive ellipticals, five with extended, potentially star-forming multiphase gas and five single-phase ellipticals with no star formation. The ratio of cooling time to freefall time at 1--10 kpc in the multiphase galaxies is tc/tff ~10, indicating that precipitation-driven feedback limits cooling but does not eliminate condensation. In the same region of the single-phase galaxies, the radial profiles of gas entropy are consistent with a thermally stable (tc/tff > 20) supernova-driven outflow that sweeps stellar ejecta out of the galaxy. However, in one of those single-phase ellipticals (NGC 4261) we find tc/tff < 10 at < 300 pc. Notably, its jets ar...

  17. Feedbacks in a simple prognostic tropical climate model

    SciTech Connect (OSTI)

    Sherwood, S.C. (Scripps Institution of Oceanography, La Jolla, CA (United States))

    1999-07-01T23:59:59.000Z

    A simple four-cell model of the tropical atmosphere in equilibrium with its boundaries is introduced, which can support a variable diabatic circulation and prognostic temperature and humidity profiles. The model is used to predict atmospheric perturbations away from the observed base state. Prognostic variables include radiation, surface fluxes, and dynamic transports, with temperature and water vapor levels determined by conservation constraints. The model includes a specially developed water vapor scheme that performs favorably compared with observations. The model is used to simulate the local and nonlocal sensitivity of the tropical maritime atmosphere to changes in surface temperature and other boundary conditions at very large horizontal scales. The main findings are as follows: (i) The sensitivity of boundary layer convergence to sea surface temperature (SST) variations depends on the behavior of convective heating over cooler regions and may be overestimated by heuristic models that ignore or oversimplify thermodynamic and radiative constraints; (ii) The maintenance of humidity equilibrium over weakly convective areas is modulated by local radiative feedback; (iii) Evaporation feedbacks on SST may be overestimated by heuristic arguments that do not carefully treat atmospheric water transport. An explanation for the constant-relative humidity behavior of general circulation models under climate changes is also offered based on the results.

  18. Cloud Feedbacks on Climate: A Challenging Scientific Problem

    ScienceCinema (OSTI)

    Norris, Joe [Scripps Institution of Oceanography, University of California, San Diego, California, USA

    2010-09-01T23:59:59.000Z

    One reason it has been difficult to develop suitable social and economic policies to address global climate change is that projected global warming during the coming century has a large uncertainty range. The primary physical cause of this large uncertainty range is lack of understanding of the magnitude and even sign of cloud feedbacks on the climate system. If Earth's cloudiness responded to global warming by reflecting more solar radiation back to space or allowing more terrestrial radiation to be emitted to space, this would mitigate the warming produced by increased anthropogenic greenhouse gases. Contrastingly, a cloud response that reduced solar reflection or terrestrial emission would exacerbate anthropogenic greenhouse warming. It is likely that a mixture of responses will occur depending on cloud type and meteorological regime, and at present, we do not know what the net effect will be. This presentation will explain why cloud feedbacks have been a challenging scientific problem from the perspective of theory, modeling, and observations. Recent research results on observed multidecadal cloud-atmosphere-ocean variability over the Pacific Ocean will also be shown, along with suggestions for future research.

  19. Cloud Feedbacks on Climate: A Challenging Scientific Problem

    SciTech Connect (OSTI)

    Norris, Joel (Scripps Institution of Oceanography, UC San Diego) [Scripps Institution of Oceanography, UC San Diego

    2010-05-10T23:59:59.000Z

    One reason it has been difficult to develop suitable social and economic policies to address global climate change is that projected global warming during the coming century has a large uncertainty range. The primary physical cause of this large uncertainty range is lack of understanding of the magnitude and even sign of cloud feedbacks on the climate system. If Earth's cloudiness responded to global warming by reflecting more solar radiation back to space or allowing more terrestrial radiation to be emitted to space, this would mitigate the warming produced by increased anthropogenic greenhouse gases. Contrastingly, a cloud response that reduced solar reflection or terrestrial emission would exacerbate anthropogenic greenhouse warming. It is likely that a mixture of responses will occur depending on cloud type and meteorological regime, and at present, we do not know what the net effect will be. This presentation will explain why cloud feedbacks have been a challenging scientific problem from the perspective of theory, modeling, and observations. Recent research results on observed multidecadal cloud-atmosphere-ocean variability over the Pacific Ocean will also be shown, along with suggestions for future research.

  20. Measuring AGN Feedback with the Sunyaev-Zel'dovich Effect

    E-Print Network [OSTI]

    Evan Scannapieco; Robert J. Thacker; H. M. P. Couchman

    2007-09-06T23:59:59.000Z

    One of the most important and poorly-understood issues in structure formation is the role of outflows driven by active galactic nuclei (AGN). Using large-scale cosmological simulations, we compute the impact of such outflows on the small-scale distribution of the cosmic microwave background (CMB). Like gravitationally-heated structures, AGN outflows induce CMB distortions both through thermal motions and peculiar velocities, by processes known as the thermal and kinetic Sunyaev-Zel'dovich (SZ) effects, respectively. For AGN outflows the thermal SZ effect is dominant, doubling the angular power spectrum on arcminute scales. But the most distinct imprint of AGN feedback is a substantial increase in the thermal SZ distortions around elliptical galaxies, post-starburst ellipticals, and quasars, which is linearly proportional to the outflow energy. While point source subtraction is difficult for quasars, we show that by appropriately stacking microwave measurements around early-type galaxies, the new generation of small-scale microwave telescopes will be able to directly measure AGN feedback at the level important for current theoretical models.

  1. AN IMPROVED SOFT FEEDBACK V-BLAST DETECTION TECHNIQUE FOR TURBO-MIMO SYSTEMS

    E-Print Network [OSTI]

    Singer, Andrew C

    AN IMPROVED SOFT FEEDBACK V-BLAST DETECTION TECHNIQUE FOR TURBO-MIMO SYSTEMS Jun Won Choi*, Andrew-demapper) and the channel decoder exchange soft (extrinsic) information to iteratively improve system perfor- mance. Hence In this paper, an improved minimum mean square error (MMSE) soft feedback detector, called the soft input, soft

  2. Closed Loop System with Feedback Control MISO control laws SISO control law

    E-Print Network [OSTI]

    Ben-Yakar, Adela

    Closed Loop System with Feedback Control MISO control laws SISO control law Switching Control demand · Two control modes for wind turbine: MISO & SISO · Proportional Integral (PI) feedback control Modes MISO SISO Inputs Blade Pitch Angle, Generator Torque Blade Pitch Angle Output Power Power

  3. American Institute of Aeronautics and Astronautics A FEEDBACK LINEARIZING CONTROLLER FOR RELATIVE

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    American Institute of Aeronautics and Astronautics 1 A FEEDBACK LINEARIZING CONTROLLER FOR RELATIVE keeping behind a leading aircraft. The investigated approach is based on feedback linearization control. In [4] and [10], the control system was designed on a linearized model, whereas in [8] the proposed

  4. External-feedback laser cooling of molecular gases Vladan Vuleti and James K. Thompson

    E-Print Network [OSTI]

    Vuletic, Vladan

    results in a friction force. In stochastic cooling in particle accelerators 2 , an electronic delay­13 . For accelerators, an opti- cal version of stochastic cooling has also been proposed 14 . The feedback cooling, a sam- ple's center-of-mass oscillation has been damped 21 by feedback. A method using an optical

  5. Rendering of Environmental Force Feedback in Mobile Robot Teleoperation based on Fuzzy Logic

    E-Print Network [OSTI]

    Ryu, Jee-Hwan

    Rendering of Environmental Force Feedback in Mobile Robot Teleoperation based on Fuzzy Logic Ildar Farkhatdinov, Jee-Hwan Ryu and Jury Poduraev Abstract-- In this paper a study on rendering of environmen- tal to the distance between the obstacles and the mobile robot. In previous approaches force feedback was rendered

  6. Feedback Control of MHD kink instabilities on the HBT-EP tokamak

    E-Print Network [OSTI]

    · Theory and modeling tell us that minimizing the control coil- resistive wall coupling (mutual inductanceFeedback Control of MHD kink instabilities on the HBT-EP tokamak David A. Maurer American Physical Society April Meeting 5th April 2003 Philadelphia, Pennsylvania #12;Feedback Control of MHD kink

  7. Nonlinear Feedback Controllers and Compensators: A StateDependent Riccati Equation Approach

    E-Print Network [OSTI]

    rules that allow the modeler and designer to make trade­o#s between control e#ort and output error) techniques are rapidly emerging as general design and synthesis methods of nonlinear feedback controllers­based feedback controllers. 1 Introduction Linear quadratic regulation (LQR) is a well established, accepted

  8. Nonlinear Feedback Controllers and Compensators: A State-Dependent Riccati Equation Approach

    E-Print Network [OSTI]

    rules that allow the modeler and designer to make trade-offs between control effort and output error) techniques are rapidly emerging as general design and synthesis methods of nonlinear feedback controllers-based feedback controllers. 1 Introduction Linear quadratic regulation (LQR) is a well established, accepted

  9. The Impact of Stochastic Noisy Feedback on Distributed Network Utility Maximization

    E-Print Network [OSTI]

    Reisslein, Martin

    The Impact of Stochastic Noisy Feedback on Distributed Network Utility Maximization Junshan Zhang of distributed network utility maximization (NUM) algorithms hinges heavily on information feedback through, that the iterates generated by distributed P-D algorithms converge with probability one to the optimal point, under

  10. EvaluatingMobilePhonesasEnergyConsumptionFeedbackDevices MarkusWeiss*

    E-Print Network [OSTI]

    EvaluatingMobilePhonesasEnergyConsumptionFeedbackDevices MarkusWeiss* ,ClaireManagement,ETHZurich Abstract. With smart electricity meters being widely deployed, data on residential energy usage of mobile phones as an interface to provide feedback on overall and de- vice-related energy consumption

  11. Simulated Arctic atmospheric feedbacks associated with late summer sea ice anomalies

    E-Print Network [OSTI]

    Moore, John

    Simulated Arctic atmospheric feedbacks associated with late summer sea ice anomalies A. Rinke,1,2 K depend on regional and decadal variations in the coupled atmosphere-ocean-sea ice system. Citation: Rinke to investigate feedbacks between September sea ice anomalies in the Arctic and atmospheric conditions in autumn

  12. Some consideration on the (in)effectiveness of residential energy feedback systems

    E-Print Network [OSTI]

    Paulos, Eric

    Mellon University, USA {jjpierce, chloefan, jlomas, gmarcu, paulos}@cs.cmu.edu ABSTRACT Energy feedback concerning household energy consumption, a number of studies have investigated the "effectiveness" of variousSome consideration on the (in)effectiveness of residential energy feedback systems James Pierce

  13. Effects of Peer Feedback on Contribution: A Field Experiment in Wikipedia

    E-Print Network [OSTI]

    Mankoff, Jennifer

    ' contributions over time. Prior studies on peer feedback in online communities have suggested its impactEffects of Peer Feedback on Contribution: A Field Experiment in Wikipedia Haiyi Zhu, Amy Zhang on contribution, but have been limited by their correlational nature. In this paper, we conducted a field

  14. Dynamic Feedback Control of XYnR Planar Robots with n

    E-Print Network [OSTI]

    De Luca, Alessandro

    Dynamic Feedback Control of XYnR¯ Planar Robots with n Rotational Passive Joints Stefano Iannitti for an XYnR¯ planar robot with the first two joints (rotational or prismatic) actuated and n rotational be exploited to recursively design a dy- namic feedback that completely linearizes the system equations. We use

  15. Tropical Water Vapor and Cloud Feedbacks in Climate Models: A Further Assessment Using Coupled Simulations

    E-Print Network [OSTI]

    Sun, Dezheng

    ). A small change in these radiative effects of water vapor and clouds can either offset or greatly amplify global warming, we find no significant correlation between the inter-model variations in the cloud albedo feedback during ENSO and the inter-model variations in the cloud albedo feedback during global warming

  16. Feedback from the first stars and galaxies and its influence on structure formation

    E-Print Network [OSTI]

    Benedetta Ciardi

    2007-09-10T23:59:59.000Z

    Once the first sources have formed, their mass deposition, energy injection and emitted radiation can deeply affect the subsequent galaxy formation process and influence the evolution of the IGM via a number of so-called feedback effects. The word 'feedback' is by far one of the most used in modern cosmology, where it is applied to a vast range of situations and astrophysical objects. Generally speaking, the concept of feedback invokes a back reaction of a process on itself or on the causes that have produced it. The character of feedback can be either negative or positive. Here, I will review the present status of investigation of the feedback effects from the first stars and galaxies.

  17. A feedback compression star formation model and the black hole - bulge relations

    E-Print Network [OSTI]

    Bing-Xiao Xu; Xue-Bing Wu

    2007-06-05T23:59:59.000Z

    We present a "feedback compression" model to describe the galactic spheroid formation and its relation with the central nuclear activity. We suggest that the star formation itself can serve as the "positive feedback" in some extremely dense region to trigger the starburst. The star formation rate as well as the related stellar feedback-induced turbulence will be maximized under the regulation of the background dark halo's gravity. There is also stellar feedback acting inward to confine and obscure the central black hole (BH) till the BH grows sufficiently large to satisfy a balance condition between the accretion disk wind and the inward stellar feedback. The extremely vigorous star formation activity, the BH - bulge relations, the maximum velocity dispersion as well as the maximum BH mass are investigated based on such scenario, and are found to be consistent with observations.

  18. The Blast Wave Model for AGN Feedback: Effects on AGN Obscuration

    E-Print Network [OSTI]

    N. Menci; F. Fiore; S. Puccetti; A. Cavaliere

    2008-07-01T23:59:59.000Z

    We compute the effect of the galactic absorption on AGN emission in a cosmological context by including a physical model for AGN feeding and feedback in a semi-analytic model of galaxy formation. This is based on galaxy interactions as triggers for AGN accretion, and on expanding blast waves as a mechanism to propagate outwards the AGN energy injected into the interstellar medium at the center of galaxies. We first test our model against the observed number density of AGNs with different intrinsic luminosity as a function of redshift. The model yields a ''downsizing'' behavior in close agreement with the observed one for z2 and L_X 10^{22} cm^{-2} decreases with luminosity for z<1; in addition, the total (integrated over luminosity) absorbed fraction increases with redshift up to z around 2, and saturates to the value around 0.8 at higher redshifts. Finally, we predict the luminosity dependence of the absorbed fraction of AGNs with L_X< 3 10^{44} erg/s to weaken with increasing redshift. We compare our results with recent observations, and discuss their implications in the context of cosmological models of galaxy formation.

  19. MECH 466 Automatic Control (4 credits) Department of Mechanical Engineering, UBC

    E-Print Network [OSTI]

    Ollivier-Gooch, Carl

    & Sons, 2008. #12;· Modern Control Systems (11th Edition), R.Dorf and R.Bishop, Prentice-Hall, 2008 for linear feedback control systems. Students will learn how to model mechanical, electrical Control of Dynamic Systems (5th Edition), G.F.Franklin, J.D.Powell, and A.Emami-Naeini, Prentice

  20. Carbon sequestration in peatland: patterns and mechanisms of response to climate change

    E-Print Network [OSTI]

    Carbon sequestration in peatland: patterns and mechanisms of response to climate change L I S A R., 2000; Turunen et al., 2002; Kremenetski et al., 2003). Rates of carbon (C) sequestration (i.e., uptake in the climatic water budget is crucial to predicting potential feedbacks on the global carbon (C) cycle. To gain

  1. Feedback Control of Turbulent Shear Flows by Genetic Programming

    E-Print Network [OSTI]

    Duriez, Thomas; von Krbek, Kai; Bonnet, Jean-Paul; Cordier, Laurent; Noack, Bernd R; Segond, Marc; Abel, Markus; Gautier, Nicolas; Aider, Jean-Luc; Raibaudo, Cedric; Cuvier, Christophe; Stanislas, Michel; Debien, Antoine; Mazellier, Nicolas; Kourta, Azeddine; Brunton, Steven L

    2015-01-01T23:59:59.000Z

    Turbulent shear flows have triggered fundamental research in nonlinear dynamics, like transition scenarios, pattern formation and dynamical modeling. In particular, the control of nonlinear dynamics is subject of research since decades. In this publication, actuated turbulent shear flows serve as test-bed for a nonlinear feedback control strategy which can optimize an arbitrary cost function in an automatic self-learning manner. This is facilitated by genetic programming providing an analytically treatable control law. Unlike control based on PID laws or neural networks, no structure of the control law needs to be specified in advance. The strategy is first applied to low-dimensional dynamical systems featuring aspects of turbulence and for which linear control methods fail. This includes stabilizing an unstable fixed point of a nonlinearly coupled oscillator model and maximizing mixing, i.e.\\ the Lyapunov exponent, for forced Lorenz equations. For the first time, we demonstrate the applicability of genetic p...

  2. Black hole feedback in the luminous quasar PDS 456

    E-Print Network [OSTI]

    Nardini, E; Gofford, J; Harrison, F A; Risaliti, G; Braito, V; Costa, M T; Matzeu, G A; Walton, D J; Behar, E; Boggs, S E; Christensen, F E; Craig, W W; Hailey, C J; Matt, G; Miller, J M; O'Brien, P T; Stern, D; Turner, T J; Ward, M J

    2015-01-01T23:59:59.000Z

    The evolution of galaxies is connected to the growth of supermassive black holes in their centers. During the quasar phase, a huge luminosity is released as matter falls onto the black hole, and radiation-driven winds can transfer most of this energy back to the host galaxy. Over five different epochs, we detected the signatures of a nearly spherical stream of highly ionized gas in the broadband X-ray spectra of the luminous quasar PDS 456. This persistent wind is expelled at relativistic speeds from the inner accretion disk, and its wide aperture suggests an effective coupling with the ambient gas. The outflow's kinetic power larger than 10^46 ergs per second is enough to provide the feedback required by models of black hole and host galaxy co-evolution.

  3. Feedback-induced oscillations in one-dimensional colloidal transport

    E-Print Network [OSTI]

    Ken Lichtner; Andrey Pototsky; Sabine H. L. Klapp

    2012-09-05T23:59:59.000Z

    We investigate a driven, one-dimensional system of colloidal particles in a periodically currogated narrow channel subject to a time-delayed feedback control. Our goal is to identify conditions under which the control induces oscillatory, time-periodic states. The investigations are based on the Fokker-Planck equation involving the density distribution of the system. First, by using the numerical continuation technique, we determine the linear stability of a stationary density. Second, the nonlinear regimes are analyzed by studying numerically the temporal evolution of the first moment of the density distribution. In this way we construct a bifurcation diagram revealing the nature of the instability. Apart from the case of a system with periodic boundary conditions, we also consider a microchannel of finite length. Finally, we study the influence of (repulsive) particle interactions based on Dynamical Density Functional Theory (DDFT).

  4. Radio-AGN Feedback: When the Little Ones were Monsters

    E-Print Network [OSTI]

    Williams, W L

    2015-01-01T23:59:59.000Z

    We present a study of the evolution of the fraction of radio-loud active galactic nuclei (AGN) as a function of their host stellar mass. We make use of two samples of radio galaxies: one in the local universe, $0.01 10^{24}$ W/Hz at z ~ 1-2 while the radio-loud fraction for higher mass galaxies ($M_* > 10^{11.25}$ M$_{\\odot}$) remains the same. We argue that this increase is driven largely by the increase in cold or radiative mode accretion with increasing cold gas supply at earlier epochs. The increasing population of low mass Radio-Loud AGN can thus explain the upturn in the Radio Luminosity Function (RLF) at high redshift which is important for understanding the impact of AGN feedback in galaxy evolution.

  5. Feedback-controlled laser fabrication of micromirror substrates

    E-Print Network [OSTI]

    Benjamin Petrak; Kumarasiri Konthasinghe; Sonia Perez; Andreas Muller

    2012-06-11T23:59:59.000Z

    Short (40-200 microseconds) single focused CO2 laser pulses of energy of about 100 microJ were used to fabricate high quality concave micromirror templates on silica and fluoride glass. The ablated features have diameters of 20-100 microns and average root-mean-square (RMS) surface microroughness near their center of less than 0.2 nm. Temporally monitoring the fabrication process revealed that it proceeds on a time scale shorter than the laser pulse duration. We implement a fast feedback control loop (20 kHz bandwidth) based on the light emitted by the sample that ensures an RMS size dispersion of less than 5 percent in arrays on chips or in individually fabricated features on an optical fiber tip, a significant improvement over previous approaches using longer pulses and open loop operation.

  6. Controlling unstable chaos: Stabilizing chimera states by feedback

    E-Print Network [OSTI]

    Jan Sieber; Oleh Omel'chenko; Matthias Wolfrum

    2013-12-18T23:59:59.000Z

    We present a control scheme that is able to find and stabilize an unstable chaotic regime in a system with a large number of interacting particles. This allows us to track a high dimensional chaotic attractor through a bifurcation where it loses its attractivity. Similar to classical delayed feedback control, the scheme is non-invasive, however, only in an appropriately relaxed sense considering the chaotic regime as a statistical equilibrium displaying random fluctuations as a finite size effect. We demonstrate the control scheme for so-called chimera states, which are coherence-incoherence patterns in coupled oscillator systems. The control makes chimera states observable close to coherence, for small numbers of oscillators, and for random initial conditions.

  7. Maxwell's demon in biochemical signal transduction with feedback loop

    E-Print Network [OSTI]

    Sosuke Ito; Takahiro Sagawa

    2015-04-15T23:59:59.000Z

    Signal transduction in living cells is vital to maintain life itself, where information transfer in noisy environment plays a significant role. In a rather different context, the recent intensive researches of "Maxwell's demon" - a feedback controller that utilizes information of individual molecules - has led to a unified theory of information and thermodynamics. Here we combine these two streams of researches, and show that the second law of thermodynamics with information reveals the fundamental limit of the robustness of signal transduction against environmental fluctuations. Especially, we found that the degree of robustness is quantitatively characterized by an informational quantity called transfer entropy. Our information-thermodynamic approach is applicable to biological communication inside cells, in which there is no explicit channel coding in contrast to artificial communication. Our result would open up a novel biophysical approach to understand information processing in living systems on the basis of the fundamental information-thermodynamics link.

  8. Measuring AGN Feedback with the Sunyaev-Zel'dovich Effect

    E-Print Network [OSTI]

    Scannapieco, Evan; Couchman, H M P

    2007-01-01T23:59:59.000Z

    One of the most important and poorly-understood issues in structure formation is the role of outflows driven by active galactic nuclei (AGN). Using large-scale cosmological simulations, we compute the impact of such outflows on the small-scale distribution of the cosmic microwave background (CMB). Like gravitationally-heated structures, AGN outflows induce CMB distortions both through thermal motions and peculiar velocities, by processes known as the thermal and kinetic Sunyaev-Zel'dovich (SZ) effects, respectively. For AGN outflows the thermal SZ effect is dominant, doubling the angular power spectrum on arcminute scales. But the most distinct imprint of AGN feedback is a substantial increase in the thermal SZ distortions around elliptical galaxies, post-starburst ellipticals, and quasars, which is linearly proportional to the outflow energy. While point source subtraction is difficult for quasars, we show that by appropriately stacking microwave measurements around early-type galaxies, the new generation of...

  9. Multistable jittering in oscillators with pulsatile delayed feedback

    E-Print Network [OSTI]

    Vladimir Klinshov; Leonhard Lücken; Dmitry Shchapin; Vladimir Nekorkin; Serhiy Yanchuk

    2015-05-27T23:59:59.000Z

    Oscillatory systems with time-delayed pulsatile feedback appear in various applied and theoretical research areas, and received a growing interest in the last years. For such systems, we report a remarkable scenario of destabilization of a periodic regular spiking regime. In the bifurcation point numerous regimes with non-equal interspike intervals emerge simultaneously. We show that this bifurcation is triggered by the steepness of the oscillator's phase resetting curve and that the number of the emerging, so-called "jittering" regimes grows exponentially with the delay value. Although this appears as highly degenerate from a dynamical systems viewpoint, the "multi-jitter" bifurcation occurs robustly in a large class of systems. We observe it not only in a paradigmatic phase-reduced model, but also in a simulated Hodgkin-Huxley neuron model and in an experiment with an electronic circuit.

  10. Generalization of neuron network model with delay feedback

    E-Print Network [OSTI]

    Sanjeet Maisnam; R. K. Brojen Singh

    2015-07-16T23:59:59.000Z

    We present generalized delayed neural network (DNN) model with positive delay feedback and neuron history. The local stability analysis around trivial local equilibria of delayed neural networks has applied and determine the conditions for the existence of zero root. We develop few innovative delayed neural network models in different dimensions through transformation and extension of some existing models. We found that zero root can have multiplicity two under certain conditions. We further show how the characteristic equation can have zero root and its multiplicity is dependent on the conditions undertaken. Finally, we generalize the neural network of $N$ neurons through which we determine the general form of Jacobian of the linear form and corresponding characteristic equation of the system.

  11. Local and Global Radiative Feedback from Population III Star Formation

    E-Print Network [OSTI]

    O'Shea, Brian W

    2010-01-01T23:59:59.000Z

    We present an overview of recent work that focuses on understanding the radiative feedback processes that are potentially important during Population III star formation. Specifically, we examine the effect of the Lyman-Werner (photodissociating) background on the early stages of primordial star formation, which serves to delay the onset of star formation in a given halo but never suppresses it entirely. We also examine the effect that both photodissociating and ionizing radiation in I-fronts from nearby stellar systems have on the formation of primordial protostellar clouds. Depending on the strength of the incoming radiation field and the central density of the halos, Pop III star formation can be suppressed, unaffected, or even enhanced. Understanding these and other effects is crucial to modeling Population III star formation and to building the earliest generations of galaxies in the Universe.

  12. Dual Feedback Controlled High Performance Ar Seeded ELMy H-mode Discharges in JET including Trace Tritium Experiments

    E-Print Network [OSTI]

    Dual Feedback Controlled High Performance Ar Seeded ELMy H-mode Discharges in JET including Trace Tritium Experiments

  13. Self-Regulated Fueling of Galaxy Centers: Evidence for Star-Formation Feedback in IC342's Nucleus

    E-Print Network [OSTI]

    E. Schinnerer; T. Boeker; D. S. Meier; D. Calzetti

    2008-08-06T23:59:59.000Z

    Using new, high-resolution interferometric observations of the CO and HCN molecules, we directly compare the molecular and ionized components of the interstellar medium in the center of the nearby spiral galaxy IC342, on spatial scales of ~ 10pc. The morphology of the tracers suggests that the molecular gas flow caused by a large-scale stellar bar has been strongly affected by the mechanical feedback from recent star formation activity within the central 100pc in the nucleus of the galaxy. Possibly, stellar winds and/or supernova shocks originating in the nuclear star cluster have compressed, and likely pushed outward, the infalling molecular gas, thus significantly reducing the gas supply to the central 10pc. Although our analysis currently lacks kinematic confirmation due to the face-on orientation of IC342, the described scenario is supported by the generally observed repetitive nature of star formation in the nuclear star clusters of late-type spiral galaxies.

  14. IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 62, NO. 4, FEBRUARY 15, 2014 993 Adaptive Limited Feedback for MISO Wiretap

    E-Print Network [OSTI]

    Swindlehurst, A. Lee

    Feedback for MISO Wiretap Channels With Cooperative Jamming Minyan Pei, A. Lee Swindlehurst, Fellow, IEEE--Cooperative jamming, feedback bits allocation, limited feedback, MISO wiretap channel. I. INTRODUCTION P HYSICAL layer for mul- tiple-input single-output (MISO) wiretap channels, which have Manuscript received May 30, 2013

  15. IEEE TRANSACTIONS ON AUTOMATIC CONTROL, VOL. 42, NO. 4, APRIL 1997 473 Robust Feedback Stabilization of Chemical Reactors

    E-Print Network [OSTI]

    Bastin, Georges

    of the controllers. Index Terms--Chemical reactors, robust feedback stabilization, robust observer, temperature control. I. INTRODUCTION THE DESIGN of stabilizing feedback control laws for unstable chemical reactors.g., [2]). The feedback control of chemical reactors is a problem which is made difficult by the inherent

  16. Feedback: Towards Dynamic Behavior and Secure Routing for Wireless Sensor Zhen Cao, Jianbin Hu, Zhong Chen, Maoxing Xu, Xia Zhou

    E-Print Network [OSTI]

    Ramkumar, Mahalingam

    Feedback: Towards Dynamic Behavior and Secure Routing for Wireless Sensor Networks Zhen Cao, Peking University Network and Information Security Laboratory Beijing, China { caozhen, hjbin, chen, xumx feedback based secure routing proto- col. Feedback, from both the nearby neighbors and base stations

  17. Enhancing parameter precision of optimal quantum estimation by direct quantum feedback

    E-Print Network [OSTI]

    Qiang Zheng; Li Ge; Yao Yao; Qi-jun Zhi

    2015-03-01T23:59:59.000Z

    Various schemes have been proposed to overcome the drawback of the decoherence on quantum-enhanced parameter estimation. Here we suggest an alternative method, quantum feedback, to enhance the parameter precision of optimal quantum estimation of a dissipative qubit by investigating its dynamics of quantum Fisher information. We find that compared with the case without feedback, the quantum Fisher information of the dissipative qubit in the case of feedback has a large maximum value in time evolution and a smaller decay rate in the long time.

  18. MHD computation of feedback of resistive-shell instabilities in the reversed field pinch

    SciTech Connect (OSTI)

    Zita, E.J.; Prager, S.C. (Wisconsin Univ., Madison, WI (United States). Plasma Physics Research); Ho, Y.L.; Schnack, D.D (Science Applications International Corp., San Diego, CA (United States))

    1992-05-01T23:59:59.000Z

    MHD computation demonstrates that feedback can sustain reversal and reduce loop voltage in resistive-shell reversed field pinch (RFP) plasmas. Edge feedback on {approximately}2R/a tearing modes resonant near axis is found to restore plasma parameters to nearly their levels with a close-fitting conducting shell. When original dynamo modes are stabilized, neighboring tearing modes grow to maintain the RFP dynamo more efficiently. This suggests that experimentally observed limits on RFP pulselengths to the order of the shell time can be overcome by applying feedback to a few helical modes.

  19. Engineering steady states using jump-based feedback for multipartite entanglement generation

    SciTech Connect (OSTI)

    Stevenson, R. N.; Hope, J. J.; Carvalho, A. R. R. [Department of Quantum Sciences, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

    2011-08-15T23:59:59.000Z

    We investigate the use of quantum-jump-based feedback to manipulate the stability of multipartite entangled dark states in an open quantum system. Using the model proposed in Phys. Rev. A 76, 010301(R) (2007) for a pair of atoms, we show a general strategy to produce many-body singlet stationary entangled states for larger number of atoms. In the case of four qubits, we propose a simple local feedback control that, although not optimal, is realistic and stabilizes a highly entangled state. We discuss the limitations and analyze alternative strategies within the framework of direct jump feedback schemes.

  20. Feedback control of torsion balance in measurement of gravitational constant G with angular acceleration method

    SciTech Connect (OSTI)

    Quan, Li-Di [MOE Key Laboratory of Fundamental Physical Quantities Measurements, School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China) [MOE Key Laboratory of Fundamental Physical Quantities Measurements, School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); School of Automation, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Xue, Chao; Shao, Cheng-Gang; Yang, Shan-Qing; Tu, Liang-Cheng; Luo, Jun, E-mail: junluo@mail.hust.edu.cn [MOE Key Laboratory of Fundamental Physical Quantities Measurements, School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)] [MOE Key Laboratory of Fundamental Physical Quantities Measurements, School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Wang, Yong-Ji [School of Automation, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)] [School of Automation, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

    2014-01-15T23:59:59.000Z

    The performance of the feedback control system is of central importance in the measurement of the Newton's gravitational constant G with angular acceleration method. In this paper, a PID (Proportion-Integration-Differentiation) feedback loop is discussed in detail. Experimental results show that, with the feedback control activated, the twist angle of the torsion balance is limited to 7.3×10{sup ?7} rad /?( Hz ) at the signal frequency of 2?mHz, which contributes a 0.4 ppm uncertainty to the G value.

  1. Radiative feedback and cosmic molecular gas: numerical method

    E-Print Network [OSTI]

    Margarita Petkova; Umberto Maio

    2012-02-27T23:59:59.000Z

    We present results from self-consistent 3D numerical simulations of cosmic structure formation with a multi-frequency radiative transfer scheme and non-equilibrium molecular chemistry of 13 primordial species (e-, H, H+, H-, He, He+, He++, H2, H2+, D, D+, HD, HeH+), performed by using the simulation code GADGET. We describe our implementation and show tests for ionized sphere expansion in a static and dynamic density field around a central radiative source, and for cosmological abundance evolution coupled with the cosmic microwave background radiation. As a demonstrative application of radiative feedback on molecular gas, we run also cosmological simulations of early structure formation in a ~1Mpc size box. Our tests agree well with analytical and numerical expectations. Consistently with other works, we find that ionization fronts from central sources can boost H2 fractions in shock-compressed gas. The tight dependence on H2 lead to a corresponding boost of HD fractions, as well. We see a strong lowering of the the typical molecular abundances up to several orders of magnitudes which partially hinders further gas collapse of pristine neutral gas, and clearly suggests the need of re-ionized gas or metal cooling for the formation of the following generation of structures.

  2. Feedback control of inertial microfluidics using axial control forces

    E-Print Network [OSTI]

    Christopher Prohm; Holger Stark

    2014-02-03T23:59:59.000Z

    Inertial microfluidics is a promising tool for many lab-on-a-chip applications. Particles in channel flows with Reynolds numbers above one undergo cross-streamline migration to a discrete set of equilibrium positions in square and rectangular channel cross sections. This effect has been used extensively for particle sorting and the analysis of particle properties. Using the lattice Boltzmann method, we determine equilibrium positions in square and rectangular cross sections and classify their types of stability for different Reynolds numbers, particle sizes, and channel aspect ratios. Our findings thereby help to design microfluidic channels for particle sorting. Furthermore, we demonstrate how an axial control force, which slows down the particles, shifts the stable equilibrium position towards the channel center. Ultimately, the particles then stay on the centerline for forces exceeding a threshold value. This effect is sensitive to particle size and channel Reynolds number and therefore suggests an efficient method for particle separation. In combination with a hysteretic feedback scheme, we can even increase particle throughput.

  3. Feedbacks between hydrological heterogeneity and bioremediation induced biogeochemical transformations

    SciTech Connect (OSTI)

    Englert, A.; Hubbard, S.S.; Williams, K.H.; Li, L.; Steefel, C.I.

    2009-04-15T23:59:59.000Z

    For guiding optimal design and interpretation of in-situ treatments that strongly perturb subsurface systems, knowledge about the spatial and temporal patterns of mass transport and reaction intensities are important. Here, a procedure was developed and applied to time-lapse concentrations of a conservative tracer (bromide), an injected amendment (acetate) and reactive species (iron(II), uranium(VI) and sulfate) associated with two field scale biostimulation experiments, which were conducted successively at the same field location over two years. The procedure is based on a temporal moment analysis approach that relies on a streamtube approximation. The study shows that biostimulated reactions can be considerably influenced by subsurface hydrological and geochemical heterogeneities: the delivery of bromide and acetate and the intensity of the sulfate reduction is interpreted to be predominantly driven by the hydrological heterogeneity, while the intensity of the iron reduction is interpreted to be primarily controlled by the geochemical heterogeneity. The intensity of the uranium(VI) reduction appears to be impacted by both the hydrological and geochemical heterogeneity. Finally, the study documents the existence of feedbacks between hydrological heterogeneity and remediation-induced biogeochemical transformations at the field scale, particularly the development of precipitates that may cause clogging and flow rerouting.

  4. Feedback from Protostellar Outflows in Star and Star Cluster Formation

    E-Print Network [OSTI]

    Christopher D. Matzner

    2000-07-13T23:59:59.000Z

    Magnetic stresses collimate protostellar winds into a common distribution of force with angle. Sweeping into the ambient medium, such winds drive bipolar molecular outflows whose properties are insensitive to the distribution of ambient gas and to the details of how the wind is launched, and how its intensity varies over time. Moreover, these properties are in accord with the commonly observed features of outflows. This model is simple enough to permit a quantitative study of the feedback effects from low-mass star formation. It predicts the rate at which star-forming gas is ejected by winds, and hence the efficiency with which stars form. Applied to individual star formation, it relates the stellar initial mass function to the distribution of pre-stellar cores. Applied to cluster formation, it indicates whether the resulting stellar system will remain gravitationally bound. Using the energy injection and mass ejection implied by this model, we investigate the dynamical evolution of a molecular clump as a stellar cluster forms within it. This depends critically on the rate at which turbulence decays: it may involve equilibrium star formation (slow decay), overstable oscillations, or collapse (fast decay).

  5. Simulations of Pregalactic Structure Formation with Radiative Feedback

    E-Print Network [OSTI]

    Marie E. Machacek; Greg L. Bryan; Tom Abel

    2000-07-14T23:59:59.000Z

    We present results from three-dimensional hydrodynamic simulations of the high redshift collapse of pregalactic clouds including feedback effects from a soft H2 photodissociating UV radiation field. The simulations use an Eulerian adaptive mesh refinement technique to follow the nonequilibrium chemistry of nine chemical species with cosmological initial conditions drawn from a popular Lambda-dominated cold dark matter model. The results confirm that the soft UV background can delay the cooling and collapse of small halos (~10^6 Msun). For reasonable values of the photo-dissociating flux, the H2 fraction is in equilibrium throughout most of the objects we simulate. We determine the mass threshold for collapse for a range of soft-UV fluxes and also derive a simple analytic expression. Continuing the simulations beyond the point of initial collapse demonstrates that the fraction of gas which can cool depends mostly on the virial mass of the halo and the amount of soft-UV flux, with remarkably little scatter. We parameterize this relation, for use in semi-analytic models.

  6. Analyzing Vehicle Fuel Saving Opportunities through Intelligent Driver Feedback

    SciTech Connect (OSTI)

    Gonder, J.; Earleywine, M.; Sparks, W.

    2012-06-01T23:59:59.000Z

    Driving style changes, e.g., improving driver efficiency and motivating driver behavior changes, could deliver significant petroleum savings. This project examines eliminating stop-and-go driving and unnecessary idling, and also adjusting acceleration rates and cruising speeds to ideal levels to quantify fuel savings. Such extreme adjustments can result in dramatic fuel savings of over 30%, but would in reality only be achievable through automated control of vehicles and traffic flow. In real-world driving, efficient driving behaviors could reduce fuel use by 20% on aggressively driven cycles and by 5-10% on more moderately driven trips. A literature survey was conducted of driver behavior influences, and pertinent factors from on-road experiments with different driving styles were observed. This effort highlighted important driver influences such as surrounding vehicle behavior, anxiety over trying to get somewhere quickly, and the power/torque available from the vehicle. Existing feedback approaches often deliver efficiency information and instruction. Three recommendations for maximizing fuel savings from potential drive cycle improvement are: (1) leveraging applications with enhanced incentives, (2) using an approach that is easy and widely deployable to motivate drivers, and (3) utilizing connected vehicle and automation technologies to achieve large and widespread efficiency improvements.

  7. Stable control of distributed hysteretic systems using cellular broadcast stochastic feedback

    E-Print Network [OSTI]

    Wood, Levi Benjamin

    This work develops a provably stable broadcast feedback approach to regulating the aggregate output of a collection of stochastically behaving cellular units with pronounced hysteresis. Similar to skeletal muscle, comprised ...

  8. Coherent-feedback-induced photon blockade and optical bistability by an optomechanical controller

    E-Print Network [OSTI]

    Yu-Long Liu; Zhong-Peng Liu; Jing Zhang; Yu-xi Liu

    2014-07-11T23:59:59.000Z

    It is well-known that some nonlinear phenomena such as strong photon blockade are hard to be observed in optomechanical system with current experimental technology. Here, we present a coherent feedback control strategy in which a linear cavity is coherently controlled by an optomechanical controller in a feedback manner. The coherent feedback loop transfers and enhances quantum nonlinearity from the controller to the controlled cavity, which makes it possible to observe strong nonlinear effects in either linear cavity or optomechanical cavity. More interestingly, we find that the strong photon blockade under single-photon optomechanical weak coupling condition could be observed in the quantum regime. Additionally, the coherent feedback loop leads to two-photon and multiphoton tunnelings for the controlled linear cavity, which are also typical quantum nonlinear phenomenon. We hope that our work can give new perspectives in engineering nonlinear quantum phenomena.

  9. Can Feedback Traders Rock the Markets? A Logistic Tale of Persistence and Chaos

    E-Print Network [OSTI]

    Tambakis, Demosthenes N

    This paper introduces a nonlinear feedback trading model at high frequency. All price adjustment is endogenous, driven by asset return and volatility in the previous trading period. There is no stochastic uncertainty or asymmetric information...

  10. Feedback Stabilization of Fed-Batch Bioreactors: Non-Monotonic Growth Kinetics

    E-Print Network [OSTI]

    Bastin, Georges

    Feedback Stabilization of Fed-Batch Bioreactors: Non-Monotonic Growth Kinetics Ilse Y. Smets's yeast, food additives, and recom- binant proteins), optimization and control of fed-batch bioreactors

  11. Adaptive feedback control of ultrafast semiconductor nonlinearities J. Kunde,a)

    E-Print Network [OSTI]

    Keller, Ursula

    that adaptive feedback optical pulse shaping can be used to control ultrafast semiconductor nonlinearities insight into the interaction of semiconduc- tors and ultrafast optical pulses. Specifically, we develop spectroscopy. More- over, the optimized pulse shape can substantially enhance ultrafast semiconductor

  12. Microfluidic device incorporating closed loop feedback control for uniform and tunable production of micro-droplets

    E-Print Network [OSTI]

    Rothstein, Jonathan

    Microfluidic device incorporating closed loop feedback control for uniform and tunable production, we have designed a microfluidic-based technology utilizing elementary microchannel geometries initial development using flow-focusing microfluidic geometry for droplet formation, computer

  13. Feedback-controlled resonance and temporal response modulations in silicon microring resonators

    E-Print Network [OSTI]

    Poon, Andrew Wing On

    electrically-tunable silicon microring resonators with waveguide-coupled feedback for channel filter [9 layer on a 1-m-thick buried-oxide layer. The rib waveguide and the microring have a designed waveguide

  14. A vibrotactile display design for the feedback of external prosthesis sensory information to the amputee wearer

    E-Print Network [OSTI]

    Chew, Andrea W. (Andrea Wae-Ping)

    2006-01-01T23:59:59.000Z

    This thesis documents the development of a vibrotactile display to be incorporated into a powered ankle-foot prosthesis. Although existing devices have addressed the need for tactile and proprioceptive feedback in external ...

  15. Permafrost degradation and methane: low risk of biogeochemical climate-warming feedback

    E-Print Network [OSTI]

    Gao, Xiang

    Climate change and permafrost thaw have been suggested to increase high latitude methane emissions that could potentially represent a strong feedback to the climate system. Using an integrated earth-system model framework, ...

  16. Listening to Our Students: Enhancing Library Instruction Through a Qualitative Assessment of Student Feedback

    E-Print Network [OSTI]

    Goodwin, Susan; Budzise-Weaver, Tina

    Listening to Our Students: Enhancing Library Instruction Through a Qualitative Assessment of Student Feedback Susan P. Goodwin1 and Tina Budzise-Weaver2 1Associate Professor & Head of Public and Learning Services, Texas A&M University Libraries...

  17. Free and forced tropical variability: role of the wind-evaporation-sea surface temperature (WES) feedback

    E-Print Network [OSTI]

    Mahajan, Salil

    2009-05-15T23:59:59.000Z

    The Wind-Evaporation-Sea Surface Temperature (WES) feedback is believedto play an important role in the tropics, where climate variability is governed byatmosphere-ocean coupled interactions. This dissertation reports on studies to distinctlyisolate...

  18. Using a Fingertip Tactile Device to Substitute Kinesthetic Feedback in Haptic Interaction

    E-Print Network [OSTI]

    Siena, Università di

    feedback provided by the electric motor of the joystick is nearly indistinguishable from the sensation felt environment, haptic interfaces, of the impedance type, available today use active input devices as motors

  19. Performing temperature feedback controlled tissue photo-coagulation using magnetic resonance thermometry

    E-Print Network [OSTI]

    Sampath, Smita

    1999-01-01T23:59:59.000Z

    depth observed (lesion size) was measured. The results obtained show that the temperature feedback controlled system developed has the ability to control the temperature at a desired point within the tissue non-invasively and for the desired time length...

  20. The road to multi-dimensional magnetic levitation : realizing two-dimensional control in classical feedback

    E-Print Network [OSTI]

    Hlebowitsh, Paul Gerardus

    2012-01-01T23:59:59.000Z

    A stable multi-dimensional magnetic levitator was characterized and implemented. This thesis contains a full analysis of the feedback specifications, a short summary of the circuits used in the design of the setup, and ...

  1. A Dynamic Feedback Model for High Repetition Rate LINAC-Driven FELS

    SciTech Connect (OSTI)

    Mellado Munoz, M.; Doolittle, L.; Emma, P.; Huang, G.; Ratti, A.; Serrano, C.; Byrd, J. M.

    2012-05-20T23:59:59.000Z

    One of the concepts for the next generation of linacdriven FELs is a CW superconducting linac driving an electron beam with MHz repetition rates. One of the challenges for next generation FELs is improve the stability of the xray pulses by improving the shot-to-shot stability of the energy, charge, peak current, and timing jitter of the electron beam. A high repetition rate FEL with a CW linac presents an opportunity to use a variety of broadband feedbacks to stabilize the beam parameters. To understand the performance of such a feedback system, we are developing a dynamic model of the machine with a focus on the longitudinal beam properties. The model is being developed as an extension of the LITrack code and includes the dynamics of the beam-cavity interaction, RF feedback, beam-based feedback, and multibunch effects. In this paper, we present a detailed description of this model.

  2. Participant/assessor personality characteristics that influence feedback acceptance in developmental assessment centers

    E-Print Network [OSTI]

    Bell, Suzanne Tamara

    2001-01-01T23:59:59.000Z

    The objective of the present study was to determine whether specified factors influenced the acceptance of feedback by participants (N = 113) in an operational developmental assessment center. Specifically, the relationship between participants...

  3. Vehicle Technologies Office Merit Review 2014: Look-Ahead Driver Feedback and Powertrain Management

    Broader source: Energy.gov [DOE]

    Presentation given by Eaton at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about look-ahead driver feedback and...

  4. Development of an isolated flyback converter employing boundary-mode operation and magnetic flux sensing feedback

    E-Print Network [OSTI]

    Kenia, Mayur V. (Mayur Vasant), 1981-

    2004-01-01T23:59:59.000Z

    This thesis focuses on the marriage of magnetic-flux-sensing feedback and boundary-mode operation in a flyback converter to create a simple, small, low-cost, isolated, and tightly regulated power supply. Although each ...

  5. Microsoft Word - PR 01 13 BPA to meet with public for feedback...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    1 13 Bonneville Power Administration FOR IMMEDIATE RELEASE Thursday, Jan. 3, 2013 CONTACT: Teresa Waugh, 503-230-7536 or 503-230-5131 BPA to meet with public for feedback on...

  6. A large ozone-circulation feedback and its implications for global warming assessments

    E-Print Network [OSTI]

    Nowack, Peer J.; Abraham, N. Luke; Maycock, Amanda C.; Braesicke, Peter; Gregory, Jonathan M.; Joshi, Manoj M.; Osprey, Annette; Pyle, John A.

    2014-12-01T23:59:59.000Z

    as a key region for further study and 176 emphasize the need for similar studies; including other climate feedbacks and their 177 interactions in increasingly sophisticated Earth system models. Our results imply that 178 model- and scenario...

  7. Final Report on the Fuel Saving Effectiveness of Various Driver Feedback Approaches

    SciTech Connect (OSTI)

    Gonder, J.; Earleywine, M.; Sparks, W.

    2011-03-01T23:59:59.000Z

    This final report quantifies the fuel-savings opportunities from specific driving behavior changes, identifies factors that influence drivers' receptiveness to adopting fuel-saving behaviors, and assesses various driver feedback approaches.

  8. arXiv:cond-mat/0302529v126Feb2003 Feedback cooling of a nanomechanical resonator

    E-Print Network [OSTI]

    by the `passive' refrigeration technique. To perform such feedback cooling the resonator must be monitored external magnetic field. We will analyze the first system, although the results should apply to the second

  9. 2.14 / 2.140 Analysis and Design of Feedback Control Systems, Spring 2007

    E-Print Network [OSTI]

    Trumper, David

    This course develops the fundamentals of feedback control using linear transfer function system models. It covers analysis in time and frequency domains; design in the s-plane (root locus) and in the frequency domain (loop ...

  10. Summary of Feedback Collected for the EIA Program (February June, 2011)

    E-Print Network [OSTI]

    Rau, Don C.

    1 Summary of Feedback Collected for the EIA Program (February ­ June, 2011) August 12, 2011 ......................................................................... 12 CUSTOMER SATISFACTION SURVEY FOR APPLICANTS (JUNIOR SCIENTISTS) ....... 13 Major Highlights for Improving the EIA Program............................................................................ 17

  11. Coordination of Voltage and Frequency Feedback in Load-Frequency Control Capability of Wind Turbine

    E-Print Network [OSTI]

    Silva, Filipe Faria Da

    Coordination of Voltage and Frequency Feedback in Load-Frequency Control Capability of Wind Turbine-Frequency Control (LFC) is gradually shifted to Variable Speed Wind Turbines (VSWTs). In order to equip VSWT

  12. Web-based feedback system: the life cycle management as continuous maintenance of apartment facility information 

    E-Print Network [OSTI]

    Jeong, Jin Su

    2006-10-30T23:59:59.000Z

    This research investigates the feasibility of web technology as a means of delivering facility information for better support of facility operations and maintenance. This study proposes a web-based feedback system as a ...

  13. Poisoned Feedback: The Impact of Malicious Users in Closed-Loop Multiuser MIMO Systems

    E-Print Network [OSTI]

    Mukherjee, Amitav

    2010-01-01T23:59:59.000Z

    Accurate channel state information (CSI) at the transmitter is critical for maximizing spectral efficiency on the downlink of multi-antenna networks. In this work we analyze a novel form of physical layer attacks on such closed-loop wireless networks. Specifically, this paper considers the impact of deliberately inaccurate feedback by malicious users in a multiuser multicast system. Numerical results demonstrate the significant degradation in performance of closed-loop transmission schemes due to intentional feedback of false CSI by adversarial users.

  14. Acoustic emission feedback control for control of boiling in a microwave oven

    DOE Patents [OSTI]

    White, Terry L. (Oak Ridge, TN)

    1991-01-01T23:59:59.000Z

    An acoustic emission based feedback system for controlling the boiling level of a liquid medium in a microwave oven is provided. The acoustic emissions from the medium correlated with surface boiling is used to generate a feedback control signal proportional to the level of boiling of the medium. This signal is applied to a power controller to automatically and continuoulsly vary the power applied to the oven to control the boiling at a selected level.

  15. Feedback from galactic stellar bulges and hot gaseous haloes of galaxies

    E-Print Network [OSTI]

    Shikui Tang; Q. Daniel Wang; Yu Lu; H. J. Mo

    2008-10-30T23:59:59.000Z

    We demonstrate that the feedback from stellar bulges can play an essential role in shaping the halo gas of galaxies with substantial bulge components by conducting 1-D hydrodynamical simulations. The feedback model we consider consists of two distinct phases: 1) an early starburst during the bulge formation and 2) a subsequent long-lasting mass and energy injection from stellar winds of low-mass stars and Type Ia SNe. An energetic outward blastwave is initiated by the starburst and is maintained and enhanced by the long-lasting stellar feedback. For a MW-like galactic bulge, this blastwave sweeps up the halo gas in the proto-galaxy and heats up the surrounding medium to a scale much beyond the virial radius of the halo, thus the accretion of the halo hot gas can be completely stopped. In addition, the long-lasting feedback in the later phase powers a galactic bulge wind that is reverse-shocked at a large radius in the presence of surrounding intergalactic medium and hence maintains a hot gaseous halo. As the mass and energy injection decreases with time, the feedback evolves to a subsonic and quasi-stable outflow, which is enough to prevent halo gas from cooling. The two phases of the feedback thus re-enforce each-other's impact on the gas dynamics. The simulation results demonstrate that the stellar bulge feedback may provide a plausible solution to the long-standing problems in understanding the MW type galaxies, such as the "missing stellar feedback" problem and the "over-cooling" problem. The simulations also show that the properties of the hot gas in the subsonic outflow state depend sensitively on the environment and the formation history of the bulge. This dependence and variance may explain the large dispersion in the X-ray to B-band luminosity ratio of the low $L_X/L_B$ Es.

  16. Effects of time delay in feedback control of linear quantum systems

    E-Print Network [OSTI]

    Kazunori Nishio; Kenji Kashima; Jun-ichi Imura

    2008-11-27T23:59:59.000Z

    We investigate feedback control of linear quantum systems subject to feedback-loop time delays. In particular, we examine the relation between the potentially achievable control performance and the time delays, and provide theoretical guidelines for the future experimental setup in two physical systems, which are typical in this research field. The evaluation criterion for the analysis is given by the optimal control performance formula, the derivation of which is from the classical control theoretic results about the input-output delay systems.

  17. Feedback Control of Non-linear Quantum Systems: a Rule of Thumb

    E-Print Network [OSTI]

    Kurt Jacobs; Austin P. Lund

    2007-01-09T23:59:59.000Z

    We show that in the regime in which feedback control is most effective -- when measurements are relatively efficient, and feedback is relatively strong -- then, in the absence of any sharp inhomogeneity in the noise, it is always best to measure in a basis that does not commute with the system density matrix than one that does. That is, it is optimal to make measurements that disturb the state one is attempting to stabilize.

  18. An investigation of the performance feedback process using a self-appraisal

    E-Print Network [OSTI]

    DeGregorio, Marybeth

    1985-01-01T23:59:59.000Z

    Problems with Supervisory Feedback. Self-Appraisal and Performance Feedback 16 Disadvantages of the self-appraisal 17 The Interactive Approach. The interactive advantage. 19 20 HYPOTHESES. 22 METHOD. 25 Subjects. Performance Task Design... helpful constructive atmosphere along with high levels of employee participation and mutual goal-setting affected satisfaction with the interview, motivation to improve performance and actual performance improvements. A more detailed investigation...

  19. You must be creative! The effect of performance feedback on intrinsic motivation and creativity

    E-Print Network [OSTI]

    Benzer, Justin Kane

    2009-05-15T23:59:59.000Z

    YOU MUST BE CREATIVE! THE EFFECT OF PERFORMANCE FEEDBACK ON INTRINSIC MOTIVATION AND CREATIVITY A Thesis by JUSTIN KANE BENZER Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE December 2006 Major Subject: Psychology YOU MUST BE CREATIVE! THE EFFECT OF PERFORMANCE FEEDBACK ON INTRINSIC MOTIVATION AND CREATIVITY A Thesis by JUSTIN KANE BENZER Submitted...

  20. [PPT] Listening to Our Students: Enhancing Library Instruction Through a Qualitative Assessment of Student Feedback

    E-Print Network [OSTI]

    Goodwin, Susan; Budzise-Weaver, Tina

    2012-01-01T23:59:59.000Z

    Listening to Our Students: Enhancing Library Instruction Through a Qualitative Assessment of Student Feedback Susan P. Goodwin and Tina Budzise-Weaver U N I V E S I T Y L I B R A R I E S Student Feedback Form Assessment ? Report... • sgoodwin@library.tamu.edu Tina Budzise-Weaver • Texas A&M University Libraries • Dept. of Library and Information Sciences, University of North Texas • tmweaver@library.tamu.edu ...

  1. Development and evaluation of an advance rate feedback irrigation system (ARFIS)

    E-Print Network [OSTI]

    Latimer, Eduardo Alberto

    1987-01-01T23:59:59.000Z

    DEVELOPMENT AND EVALUATION OF AN ADVANCE RATE FEEDBACK IRRIGATION SYSTEM (ARFIS) A Thesis EDUARDO ALBERTO LATIMER Submitted to the Graduate College of Texas ALM University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE August 1987 Major Subject: Agricultural Engineering DEVELOPMENT AND EVALUATION OF AN ADVANCE RATE FEEDBACK IRRIGATION SYSTEM (ARFIS) A Thesis EDUARDO ALBERTO LATIMER Approved as to style and content by: Donald L. Reddell (Chairman) ayne...

  2. An investigation of the performance feedback process using a self-appraisal 

    E-Print Network [OSTI]

    DeGregorio, Marybeth

    1985-01-01T23:59:59.000Z

    Problems with Supervisory Feedback. Self-Appraisal and Performance Feedback 16 Disadvantages of the self-appraisal 17 The Interactive Approach. The interactive advantage. 19 20 HYPOTHESES. 22 METHOD. 25 Subjects. Performance Task Design... helpful constructive atmosphere along with high levels of employee participation and mutual goal-setting affected satisfaction with the interview, motivation to improve performance and actual performance improvements. A more detailed investigation...

  3. Optimal measurement-based feedback control for a single qubit: a candidate protocol

    E-Print Network [OSTI]

    Ashkan Balouchi; Kurt Jacobs

    2014-07-30T23:59:59.000Z

    Feedback control of quantum systems via continuous measurement involves complex nonlinear dynamics. Except in very special cases, even for a single qubit optimal feedback protocols are unknown. Not even do intuitive candidates exist for choosing the measurement basis, which is the primary non-trivial ingredient in the feedback control of a qubit. Here we present a series of arguments that suggest a particular form for the optimal protocol for a broad class of noise sources in the regime of good control. This regime is defined as that in which the control is strong enough to keep the system close to the desired state. With the assumption of this form the remaining parameters can be determined via a numerical search. The result is a non-trivial feedback protocol valid for all feedback strengths in the regime of good control. We conjecture that this protocol is optimal to leading order in the small parameters that define this regime. The protocol can be described relatively simply, and as a notable feature contains a discontinuity as a function of the feedback strength.

  4. Detection of Quasar Feedback from the Thermal Sunyaev-Zel'dovich Effect in Planck

    E-Print Network [OSTI]

    Ruan, John J; Anderson, Scott F

    2015-01-01T23:59:59.000Z

    Poorly understood feedback processes associated with highly-luminous black hole accretion in quasars may dramatically affect the properties of their host galaxies. We search for the effect of quasar feedback on surrounding gas using Planck maps of the thermal Sunyaev-Zel'dovich effect (tSZ). By stacking tSZ Compton-y maps centered on the locations of 26,686 spectroscopic quasars from the Sloan Digital Sky Survey, we detect a strong but unresolved tSZ Compton-y signal at >5 sigma significance that likely originates from a combination of virialized halo atmosphere gas and quasar feedback effects. We show that the feedback contribution to our detected quasar tSZ signal is likely to dominate over virialized halo gas by isolating the feedback tSZ component for high- and low-redshift quasars. We find that this quasar tSZ signal also scales with black hole mass and bolometric luminosity, all consistent with general expectations of quasar feedback. We estimate the mean angularly-integrated Compton-y of quasars at z~1...

  5. Terrestrial biogeochemical feedbacks in the climate system: from past to future

    SciTech Connect (OSTI)

    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

    2010-01-05T23:59:59.000Z

    The terrestrial biosphere plays a major role in the regulation of atmospheric composition, and hence climate, through multiple interlinked biogeochemical cycles (BGC). Ice-core and other palaeoenvironmental records show a fast response of vegetation cover and exchanges with the atmosphere to past climate change, although the phasing of these responses reflects spatial patterning and complex interactions between individual biospheric feedbacks. Modern observations show a similar responsiveness of terrestrial biogeochemical cycles to anthropogenically-forced climate changes and air pollution, with equally complex feedbacks. For future conditions, although carbon cycle-climate interactions have been a major focus, other BGC feedbacks could be as important in modulating climate changes. The additional radiative forcing from terrestrial BGC feedbacks other than those conventionally attributed to the carbon cycle is in the range of 0.6 to 1.6 Wm{sup -2}; all taken together we estimate a possible maximum of around 3 Wm{sup -2} towards the end of the 21st century. There are large uncertainties associated with these estimates but, given that the majority of BGC feedbacks result in a positive forcing because of the fundamental link between metabolic stimulation and increasing temperature, improved quantification of these feedbacks and their incorporation in earth system models is necessary in order to develop coherent plans to manage ecosystems for climate mitigation.

  6. Commissioning of FPGA-based Transverse and Longitudinal Bunch-by-Bunch Feedback System for the TLS

    SciTech Connect (OSTI)

    Hu, K. H.; Kuo, C. H.; Lau, W. K.; Yeh, M. S.; Hsu, S. Y.; Chou, P. J.; Wang, M. H.; Lee, Demi; Chen, Jenny; Wang, C. J.; Hsu, K. T. [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Kobayashi, K.; Nakamura, T. [JASRI/SPring-8, Hyogo (Japan); Dehler, M. [Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)

    2006-11-20T23:59:59.000Z

    Multi-bunch instabilities deteriorate beam quality, increasing beam emittance, or even causing beam loss in the synchrotron light source. The feedback system is essential to suppress multi-bunch instabilities caused by the impedances of beam ducts, and trapped ions. A new FPGA based transverse and longitudinal bunch-by-bunch feedback system have been commissioned at the Taiwan Light Source recently, A single feedback loop is used to simultaneously suppress the horizontal and the vertical multi-bunch instabilities. Longitudinal instabilities caused by cavity-like structures are suppressed by the longitudinal feedback loop. The same FPGA processor is employed in the transverse feedback and the longitudinal feedback system respectively. Diagnostic memory is included in the system to capture the bunch oscillation signal, which supports various studies.

  7. Heavy Mobile Equipment Mechanic (One Mechanic Shop)

    Broader source: Energy.gov [DOE]

    The position is a Heavy Mobile Equipment Mechanic (One Mechanic Shop) located in Kent, Washington, and will be responsible for the safe and efficient operation of a field garage performing...

  8. Carbon-nitrogen interactions regulate climate-carbon cycle feedbacks: results from an atmosphere-ocean general circulation model

    E-Print Network [OSTI]

    2009-01-01T23:59:59.000Z

    2009 P. E. Thornton et al. : Carbon-nitrogen interactionsregulate climate-carbon cycle feedbacks Monfray, P. ,T. H. : A global ocean carbon climatology: Results from

  9. A Kalman filter for feedback control of rotating external kink instabilities in the presence of noise

    SciTech Connect (OSTI)

    Hanson, Jeremy M.; De Bono, Bryan; Levesque, Jeffrey P.; Mauel, Michael E.; Maurer, David A.; Navratil, Gerald A.; Pedersen, Thomas Sunn; Shiraki, Daisuke [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States); James, Royce W. [U. S. Coast Guard Academy, New London, Connecticut 06320 (United States) and Stevens Institute of Technology, Castle Point on Hudson, Hoboken, New Jersey 07030 (United States)

    2009-05-15T23:59:59.000Z

    The simulation and experimental optimization of a Kalman filter feedback control algorithm for n=1 tokamak external kink modes are reported. In order to achieve the highest plasma pressure limits in ITER, resistive wall mode stabilization is required [T. C. Hender et al., Nucl. Fusion 47, S128 (2007)] and feedback algorithms will need to distinguish the mode from noise due to other magnetohydrodynamic activity. The Kalman filter contains an internal model that captures the dynamics of a rotating, growing n=1 mode. This model is actively compared with real-time measurements to produce an optimal estimate for the mode's amplitude and phase. On the High Beta Tokamak-Extended Pulse experiment [T. H. Ivers et al., Phys. Plasmas 3, 1926 (1996)], the Kalman filter algorithm is implemented using a set of digital, field-programmable gate array controllers with 10 {mu}s latencies. Signals from an array of 20 poloidal sensor coils are used to measure the n=1 mode, and the feedback control is applied using 40 poloidally and toroidally localized control coils. The feedback system with the Kalman filter is able to suppress the external kink mode over a broad range of phase angles between the sensed mode and applied control field. Scans of filter parameters show good agreement between simulation and experiment, and feedback suppression and excitation of the kink mode are enhanced in experiments when a filter made using optimal parameters from the scans is used.

  10. Spatial homogenization of thermal feedback regions in Monte Carlo reactor calculations

    SciTech Connect (OSTI)

    Hanna, B. R.; Gill, D. F.; Griesheimer, D. P. [Bertis Atomic Power Laboratory, Bechtel Marine Propulsion Corporation, P.O. Box 79, West Mifflin, PA 15122 (United States)

    2012-07-01T23:59:59.000Z

    An integrated thermal-hydraulic feedback module has previously been developed for the Monte Carlo transport solver, MC21. The module incorporates a flexible input format that allows the user to describe heat transfer and coolant flow paths within the geometric model at any level of spatial detail desired. The effect that the varying levels of spatial homogenization of thermal regions has on the accuracy of the Monte Carlo simulations is examined in this study. Six thermal feedback mappings are constructed from the same geometric model of the Calvert Cliffs core. The spatial homogenization of the thermal regions is varied, giving each scheme a different level of detail, and the adequacy of the spatial homogenization is determined based on the eigenvalue produced by each Monte Carlo calculation. The purpose of these numerical experiments is to determine the level of detail necessarily to accurately capture the thermal feedback effect on reactivity. Several different core models are considered: axial-flow only, axial and lateral flow, asymmetry due to control rod insertion, and fuel heating (temperature -dependent cross sections). The thermal results generated by the MC21 thermal feedback module are consistent with expectations. Based upon the numerical experiments conducted it is concluded that the amount of spatial detail necessary to accurately capture the feedback effect on reactivity is relatively small. Homogenization at the assembly level for the Calvert Cliffs PWR model results in a similar power defect to that calculated with individual pin-cells modeled as explicit thermal regions. (authors)

  11. DOES STELLAR FEEDBACK CREATE H I HOLES? A HUBBLE SPACE TELESCOPE/VERY LARGE ARRAY STUDY OF HOLMBERG II

    SciTech Connect (OSTI)

    Weisz, Daniel R.; Skillman, Evan D. [Astronomy Department, University of Minnesota, Minneapolis, MN 55455 (United States); Cannon, John M. [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, St. Paul, MN 55125 (United States); Dolphin, Andrew E. [Raytheon Company, 1151 E Hermans Rd, Tucson, AZ 85756 (United States); Kennicutt, Robert C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Lee, Janice [Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Walter, Fabian, E-mail: dweisz@astro.umn.ed, E-mail: skillman@astro.umn.ed, E-mail: jcannon@macalester.ed, E-mail: adolphin@raytheon.co, E-mail: robk@ast.cam.ac.u, E-mail: jlee@obs.carnegiescience.ed, E-mail: walter@mpia.d [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany)

    2009-10-20T23:59:59.000Z

    We use deep Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) F555W and F814W photometry of resolved stars in the M81 Group dwarf irregular galaxy Ho II to study the hypothesis that the holes identified in the neutral interstellar medium (H I) are created by stellar feedback. From the deep photometry, we construct color-magnitude diagrams (CMDs) and measure the star formation histories (SFHs) for stars contained in H I holes from two independent holes catalogs, as well as select control fields, i.e., similar sized regions that span a range of H I column densities. The CMDs reveal young (< 200 Myr) stellar populations inside all H I holes, which contain very few bright OB stars with ages less than 10 Myr, indicating they are not reliable tracers of H I hole locations while the recent SFHs confirm multiple episodes of star formation within most holes. Converting the recent SFHs into stellar feedback energies, we find that enough energy has been generated to have created all holes. However, the required energy is not always produced over a timescale that is less than the estimated kinematic age of the hole. A similar analysis of stars in the control fields finds that the stellar populations of the control fields and H I holes are statistically indistinguishable. However, because we are only sensitive to holes approx100 pc in diameter, we cannot tell if there are smaller holes inside the control fields. The combination of the CMDs, recent SFHs, and locations of young stars shows that the stellar populations inside H I holes are not coherent, single-aged, stellar clusters, as previously suggested, but rather multi-age populations distributed across each hole. From a comparison of the modeled and observed integrated magnitudes, and the locations and energetics of stars inside of H I holes, we propose a potential new model: a viable mechanism for creating the observed H I holes in Ho II is stellar feedback from multiple generations of SF spread out over tens or hundreds of Myr, and thus, the concept of an age for an H I hole is intrinsically ambiguous. For H I holes in the outer parts of Ho II, located beyond the HST/ACS coverage, we use Monte Carlo simulations of expected stellar populations to show that low level SF could provide the energy necessary to form these holes. Applying the same method to the SMC, we find that the holes that appear to be void of stars could have formed via stellar feedback from low level SF. We further find that Halpha and 24 mum emission, tracers of the most recent star formation, do not correlate well with the positions of the H I holes. However, UV emission, which traces star formation over roughly the last 100 Myr, shows a much better correlation with the locations of the H I holes.

  12. Mechanical & Industrial Engineering

    E-Print Network [OSTI]

    Mountziaris, T. J.

    Mechanical & Industrial Engineering 1 Welcome MIE Industrial Advisory Board October 15, 2010 #12;Mechanical & Industrial Engineering 2 MIE Dorothy Adams Undergraduate/Graduate Secretary David Schmidt Associate Professor & Graduate Program Director #12;Mechanical & Industrial Engineering 3 MIE James Rinderle

  13. Mechanical Engineering & Thermal Group

    E-Print Network [OSTI]

    Mojzsis, Stephen J.

    Mechanical Engineering & Thermal Group The Mechanical Engineering (ME) & Thermal Group at LASP has · STOP (Structural, Thermal, and Optical Performance) analyses of optical systems Thermal engineers lead evolved with the complexity of instrument design demands, LASP mechanical engineers develop advanced

  14. Mechanical engineering Department Seminar

    E-Print Network [OSTI]

    and the Department of Mechanical Engineering Tufts University Retooling Our Energy Ecosystem: challengesMechanical engineering Department Seminar Robert J. Hannemann The Gordon Institute and Chair of the Tufts Department of Mechanical Engineering. His technical and academic interests

  15. High-Gradient Tests of the Single-Cell SC Cavity with a Feedback Waveguide

    SciTech Connect (OSTI)

    Yakovlev, V.; Solyak, N.; Wu, G.; Ge, M.; Gonin, I.; Khabiboulline, T.; Ozelis, J.; Rowe, A. [Fermilab, Batavia, IL 60510 (United States); Avrakhov, P.; Kanareykin, A. [Euclid TechLabs, LLC, Solon, Ohio 44139 (United States); Rathke, J. [AES, Medford, NY 11763 (United States)

    2010-11-04T23:59:59.000Z

    Use of a superconducting (SC) traveling-wave accelerating (STWA) structure with a small phase advance per cell, rather than a standing-wave structure, may provide a significant increase in the accelerating gradient in the ILC linac [1]. For the same surface electric and magnetic fields, the STWA achieves an accelerating gradient 1.2 larger than TESLA-like standing-wave cavities. In addition, the STWA allows longer acceleration cavities, reducing the number of gaps between them. However, the STWA structure requires a SC feedback waveguide to return the few hundreds of MW of circulating RF power from the structure output to the structure input. A test single-cell cavity with feedback was designed and manufactured to demonstrate the possibility of proper processing to achieve a high accelerating gradient. The first results of high-gradient tests of a prototype 1.3 GHz single-cell cavity with feedback waveguide will be presented.

  16. On the optimal feedback control of linear quantum systems in the presence of thermal noise

    E-Print Network [OSTI]

    Marco G. Genoni; Stefano Mancini; Alessio Serafini

    2013-04-27T23:59:59.000Z

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

  17. Adaptive optimal stochastic state feedback control of resistive wall modes in tokamaks

    SciTech Connect (OSTI)

    Sun, Z.; Sen, A.K.; Longman, R.W. [Electrical Engineering Department, Columbia University, New York, New York 10027 (United States); Mechanical Engineering Department, Columbia University, New York, New York 10027 (United States)

    2006-01-15T23:59:59.000Z

    An adaptive optimal stochastic state feedback control is developed to stabilize the resistive wall mode (RWM) instability in tokamaks. The extended least-square method with exponential forgetting factor and covariance resetting is used to identify (experimentally determine) the time-varying stochastic system model. A Kalman filter is used to estimate the system states. The estimated system states are passed on to an optimal state feedback controller to construct control inputs. The Kalman filter and the optimal state feedback controller are periodically redesigned online based on the identified system model. This adaptive controller can stabilize the time-dependent RWM in a slowly evolving tokamak discharge. This is accomplished within a time delay of roughly four times the inverse of the growth rate for the time-invariant model used.

  18. Using Channel Output Feedback to Increase Throughput in Hybrid-ARQ

    E-Print Network [OSTI]

    Agrawal, Mayur; Love, David J; Balakrishnan, Venkataramanan

    2011-01-01T23:59:59.000Z

    Since its inclusion in the High Speed Downlink Packet Access (HSPDA) standard, the hybrid-ARQ protocol has become very popular in packet transmission schemes. Hybrid-ARQ combines the normal automatic repeat request (ARQ) method with error correction codes to increase reliability and throughput. The use of rate-compatible punctured turbo codes has been shown to work well for block fading channels. In this paper, we look at improving upon this performance using feedback information from the receiver; in particular, using a turbo code in conjunction with a proposed linear feedback code for the Rayleigh fading channels. The new hybrid-ARQ scheme is extended to various different multiple-antenna scenarios (MIMO/MISO/SISO) with varying amounts of feedback information. Simulations are given to illustrate gains in throughput.

  19. Tuning the external optical feedback-sensitivity of a passively mode-locked quantum dot laser

    SciTech Connect (OSTI)

    Raghunathan, R., E-mail: raghunat@vt.edu; Kovanis, V.; Lester, L. F. [Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State University, 302 Whittemore Hall, Blacksburg, Virginia 24061 (United States); Grillot, F. [Télécom ParisTech, Ecole Nationale Supérieure des Télécommunications, CNRS LTCI, 46 rue Barrault, 75634 Paris Cedex 13 (France); Mee, J. K.; Murrell, D. [Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico 87106 (United States)

    2014-07-28T23:59:59.000Z

    The external optical feedback-sensitivity of a two-section, passively mode-locked quantum dot laser operating at elevated temperature is experimentally investigated as a function of absorber bias voltage. Results show that the reverse-bias voltage on the absorber has a direct impact on the damping rate of the free-running relaxation oscillations of the optical signal output, thereby enabling interactive external control over the feedback-response of the device, even under the nearly resonant cavity configuration. The combination of high temperature operation and tunable feedback-sensitivity is highly promising from a technological standpoint, in particular, for applications requiring monolithic integration of multi-component architectures on a single chip in order to accomplish, for instance, the dual-objectives of stable pulse quality and isolation from parasitic reflections.

  20. Time-delayed feedback control of delay-coupled neurosystems and lasers

    E-Print Network [OSTI]

    Philipp Hövel; Markus A. Dahlem; Thomas Dahms; Gerald Hiller; Eckehard Schöll

    2009-12-17T23:59:59.000Z

    We discuss applications of time-delayed feedback control to delay-coupled neural systems and lasers, in the framework of the FitzHugh-Nagumo neuron model and the Lang-Kobayashi laser model, respectively. In the context of neural systems, we will point out some complex scenarios of synchronized in-phase or antiphase oscillations, bursting patterns, or amplitude death, induced by delayed coupling in combination with delayed self-feedback in simple network motifs. For optical systems, we will show that multiple time-delayed feedback, realized by a Fabry-Perot resonator coupled to the laser, provides a valuable tool for the suppression of unwanted intensity pulsations, and leads to stable continuous-wave operation.

  1. Mechanical & Aerospace Engineering

    E-Print Network [OSTI]

    Mechanical & Aerospace Engineering It is a new beginning for innovative fundamental and applied and consolidation of bulk nanocrystalline materials using mechanical alloying, the alloy development and synthesis

  2. Hopf bifurcation analysis of the generalized Lorenz system with time delayed feedback control

    E-Print Network [OSTI]

    Rachele Barresi; Maria Carmela Lombardo; Marco Sammartino

    2015-01-02T23:59:59.000Z

    In this work we propose a feedback approach to regulate the chaotic behavior of the whole family of the generalized Lorenz system, by designing a nonlinear delayed feedback control. We first study the effect of the delay on the dynamics of the system and we investigate the existence of Hopf bifurcations. Then, by using the center manifold reduction technique and the normal form theory, we derive the explicit formulas for the direction, stability and period of the periodic solutions bifurcating from the steady state at certain critical values of the delay.

  3. Development of a transient three-dimensional neutron transport code with feedback

    SciTech Connect (OSTI)

    Waddell, M.W. Jr.

    1994-07-19T23:59:59.000Z

    A new code is being developed at the Y-12 Plant for solving the time-dependent, three-dimensional Boltzmann transport model with feedback. The new code, PADK, uses the quasi-static method in its adiabatic form and is to be utilized to analyze hypothetical criticality accidents. A description of the code along with preliminary results without feedback are presented in this paper. The code is applied to 2 standard benchmark problems and the results are compared to another method. Also, the code is used to model the GODIVA reactor. Further work needed to be completed is described.

  4. Production of entanglement in Raman three-level systems using feedback

    E-Print Network [OSTI]

    R. N. Stevenson; A. R. R. Carvalho; J. J. Hope

    2010-01-10T23:59:59.000Z

    We examine the theoretical limits of the generation of entanglement in a damped coupled ion-cavity system using jump-based feedback. Using Raman transitions to produce entanglement between ground states reduces the necessary feedback bandwidth, but does not improve the overall effect of the spontaneous emission on the final entanglement. We find that the fidelity of the resulting entanglement will be limited by the asymmetries produced by vibrations in the trap, but that the concurrence remains above 0.88 for realistic ion trap sizes.

  5. Playing with positive feedback: external pressure-triggering of a star-forming disc galaxy

    E-Print Network [OSTI]

    Bieri, Rebekka; Silk, Joseph; Mamon, Gary A

    2015-01-01T23:59:59.000Z

    Feedback in massive galaxies generally involves quenching of star formation, a favored candidate being outflows from a central supermassive black hole. At high redshifts however, explanation of the huge rates of star formation often found in galaxies containing AGN may require a more vigorous mode of star formation than attainable by simply enriching the gas content of galaxies in the usual gravitationally-driven mode that is associated with the nearby Universe. Using hydrodynamical simulations, we demonstrate that AGN-pressure-driven star formation potentially provides the positive feedback that may be required to generate the accelerated star formation rates observed in the distant Universe.

  6. Effect of feedback on the control of a two-level dissipative quantum system

    E-Print Network [OSTI]

    L. C. Wang; X. L. Huang; X. X. Yi

    2008-06-10T23:59:59.000Z

    We show that it is possible to modify the stationary state by a feedback control in a two-level dissipative quantum system. Based on the geometric control theory, we also analyze the effect of the feedback on the time-optimal control in the dissipative system governed by the Lindblad master equation. These effects are reflected in the function $\\Delta_A(\\vec{x})$ and $\\Delta_B(\\vec{x})$ that characterize the optimal trajectories, as well as the switching function $\\Phi(t)$ and $\\theta(t),$ which characterize the switching point in time for the time-optimal trajectory.

  7. Combined Quantum Mechanical and Molecular Mechanics Studies of...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Mechanical and Molecular Mechanics Studies of the Electron-Transfer Reactions Involving Carbon Tetrachloride in Combined Quantum Mechanical and Molecular Mechanics Studies of the...

  8. SMSE PRECODER DESIGN IN A MULTIUSER MISO SYSTEM WITH LIMITED FEEDBACK Muhammad Nazmul Islam and Raviraj Adve

    E-Print Network [OSTI]

    Adve, Raviraj

    SMSE PRECODER DESIGN IN A MULTIUSER MISO SYSTEM WITH LIMITED FEEDBACK Muhammad Nazmul Islam in the downlink of a multi-user (MU) multiple input single output (MISO) sys- tem with quantized channel state MISO linear transceivers that exist in the limited feedback literature. Second, we show analytically

  9. Feedback Control Methodologies for Nonlinear Systems 1 S. C. Beeler 2 , H. T. Tran 3 , and H. T. Banks 4

    E-Print Network [OSTI]

    .math.ncsu.edu 4 e­mail: htbanks@eos.ncsu.edu 1 #12; 1. Introduction The optimal feedback control of a linear, then the optimal control is a linear state feedback law where the control gains are obtained by solving to the optimal control problem for general nonlinear systems; however, it is in most cases impossible to solve

  10. Test Response Compaction by an Accumulator Behaving as a Multiple Input Non-Linear Feedback Shift Register

    E-Print Network [OSTI]

    Kavousianos, Xrysovalantis

    Test Response Compaction by an Accumulator Behaving as a Multiple Input Non-Linear Feedback Shift that an accumulator can be modified to behave as a Non-Linear Feedback Shft Register suitable for test response by the proposed scheme is higher than that of the already known accumulator based compaction schemes and in most

  11. SimPilot: An exploration of modeling a highly interactive task with delayed feedback in a multitasking environment

    E-Print Network [OSTI]

    Gray, Wayne

    SimPilot: An exploration of modeling a highly interactive task with delayed feedback of cognition and the building of process models of taxiing. We describe a model, SimPilot, its initial feedback, threaded cognition; cognitive control; task switching. Introduction A good applied problem drives

  12. THE UNIVERSITY OF CALGARY One Size Does Not Fit All: Extending the Transtheoretical Model to Energy Feedback

    E-Print Network [OSTI]

    Greenberg, Saul

    of technologies that provide real-time, energy usage feedback. However, current technologies use a "one notions for designers of technology that motivates sustainable energy behaviour. Second, I show how to illustrate the application of the framework to inform energy feedback technology design. The first

  13. On Maximum Available Feedback and PID Control -1 IEEE SMC UK&RI Applied Cybernetics Dr Richard Mitchell 2005

    E-Print Network [OSTI]

    Mitchell, Richard

    On Maximum Available Feedback and PID Control - 1 IEEE SMC UK&RI Applied Cybernetics © Dr Richard Mitchell 2005 ON MAXIMUM AVAILABLE FEEDBACK AND PID CONTROL Dr Richard Mitchell, Cybernetics, University frequencies A recent IEEE SMC Paper describes a robust PID controller whose phase is flat at key frequencies

  14. Role of ocean biology-induced climate feedback in the modulation of El Nin~o-Southern Oscillation

    E-Print Network [OSTI]

    Chen, .Dake

    penetration of solar radiation in the upper ocean, present- ing a feedback from ocean biology to physics represented by the penetration depth of solar radiation in the upper ocean (Hp), a field thus servingRole of ocean biology-induced climate feedback in the modulation of El Nin~o-Southern Oscillation

  15. Introduction Space Time Codes Space Time Coding with Feedback New Thoughts Summary Space-Time Coding for Multi-Antenna

    E-Print Network [OSTI]

    Veeravalli, Venugopal

    Introduction Space Time Codes Space Time Coding with Feedback New Thoughts Summary Space 2007 #12;Introduction Space Time Codes Space Time Coding with Feedback New Thoughts Summary MIMO: Diversity vs Multiplexing Multiplexing Diversity Pictures taken from lectures notes on Space Time Coding

  16. Feedback Heating by Cosmic Rays in Clusters of Galaxies

    E-Print Network [OSTI]

    Fulai Guo; S. Peng OH

    2007-11-07T23:59:59.000Z

    Recent observations show that the cooling flows in the central regions of galaxy clusters are highly suppressed. Observed AGN-induced cavities/bubbles are a leading candidate for suppressing cooling, usually via some form of mechanical heating. At the same time, observed X-ray cavities and synchrotron emission point toward a significant non-thermal particle population. Previous studies have focused on the dynamical effects of cosmic-ray pressure support, but none have built successful models in which cosmic-ray heating is significant. Here we investigate a new model of AGN heating, in which the intracluster medium is efficiently heated by cosmic-rays, which are injected into the ICM through diffusion or the shredding of the bubbles by Rayleigh-Taylor or Kelvin-Helmholtz instabilities. We include thermal conduction as well. Using numerical simulations, we show that the cooling catastrophe is efficiently suppressed. The cluster quickly relaxes to a quasi-equilibrium state with a highly reduced accretion rate and temperature and density profiles which match observations. Unlike the conduction-only case, no fine-tuning of the Spitzer conduction suppression factor f is needed. The cosmic ray pressure, P_c/P_g heating is a very attractive alternative to mechanical heating, and may become particularly compelling if GLAST detects the gamma-ray signature of cosmic-rays in clusters.

  17. Mechanical engineering Department Seminar

    E-Print Network [OSTI]

    Lin, Xi

    Mechanical engineering Department Seminar Ju Li Professor MIT Electrochemical-mechanical actions computational and experimental research on mechanical properties of materials, and energy storage and conversion Refreshments served at 10:45 AM The creation of a nanoscale electrochemical and mechanical testing platform

  18. Micromachined force-balance feedback accelerometer with optical displacement detection

    DOE Patents [OSTI]

    Nielson, Gregory N.; Langlois, Eric; Baker, Michael; Okandan, Murat; Anderson, Robert

    2014-07-22T23:59:59.000Z

    An accelerometer includes a proof mass and a frame that are formed in a handle layer of a silicon-on-an-insulator (SOI). The proof mass is separated from the frame by a back-side trench that defines a boundary of the proof mass. The accelerometer also includes a reflector coupled to a top surface of the proof mass. An optical detector is located above the reflector at the device side. The accelerometer further includes at least one suspension spring. The suspension spring has a handle anchor that extends downwards from the device side to the handle layer to mechanically support upward and downward movement of the proof mass relative to a top surface of the proof mass.

  19. Sensory subtraction via cutaneous feedback: a novel technique to improve the transparency of robotic surgery

    E-Print Network [OSTI]

    Siena, Università di

    of robotic surgery Claudio Pacchierotti and Domenico Prattichizzo Abstract-- In this paper we present a novel technique to force feedback in robot-assisted surgery. It consists of substituting haptic force, composed teleoperation scenarios. I. INTRODUCTION Achieving a good illusion of telepresence in robotic teleoperation

  20. One Size Does Not Fit All: Applying the Transtheoretical Model to Energy Feedback Technology Design

    E-Print Network [OSTI]

    Greenberg, Saul

    to this problem. The development of energy-efficient technol- ogy (e.g. cars, homes, appliances) is one approach. While important, this is only a partial solution as people do not always use this technology in energy-efficientOne Size Does Not Fit All: Applying the Transtheoretical Model to Energy Feedback Technology Design

  1. Feedback Limits Rapid Growth of Seed Black Holes at High Redshift

    E-Print Network [OSTI]

    J. -M. Wang; Y. -M. Chen; C. Hu

    2005-12-17T23:59:59.000Z

    Seed black holes formed in the collapse of population III stars have been invoked to explain the presence of supermassive black holes at high redshift. It has been suggested that a seed black hole can grow up to $10^{5\\sim 6}\\sunm$ through highly super-Eddington accretion for a period of $\\sim 10^{6\\sim 7}$ yr between redshift $z=20\\sim 24$. We studied the feedback of radiation pressure, Compton heating and outflow during the seed black hole growth. It is found that its surrounding medium fueled to the seed hole is greatly heated by Compton heating. For a super-critical accretion onto a $10^3\\sunm$ seed hole, a Compton sphere (with a temperature $\\sim 10^6$K) forms in a timescale of $1.6\\times 10^3$yr so that the hole is only supplied by a rate of $10^{-3}$ Eddington limit from the Compton sphere. Beyond the Compton sphere, the kinetic feedback of the strong outflow heats the medium at large distance, this leads to a dramatical decrease of the outer Bondi accretion onto the black hole and avoid the accumulation of the matter. The highly super-critical accretion will be rapidly halted by the strong feedback. The seed black holes hardly grow up at the very early universe unless the strong feedback can be avoided.

  2. An HIV Feedback-Resistor: Auto-Regulatory Circuit Deactivator and Noise Buffer

    E-Print Network [OSTI]

    Leor S. Weinberger; Thomas Shenk

    2007-01-09T23:59:59.000Z

    Many viruses have the cunning ability to enter a hibernative or off state, termed latency or lysogeny. When in a latent state, the virus is unable to replicate, and its gene expression program is largely shut down. This facility for lying dormant typically ensures lifelong persistence of the virus in the host; it is also a particularly problematic obstacle in the treatment of HIV. For most viruses, the molecular regulation of entry into latency is not completely understood, but it is believed that viral gene expression must be deactivated in some way. In this study, we introduce a new regulatory motif, the feedback resistor, that enables a genetic circuit to shut off without the need for an active repressor molecule. We first show that many animal viruses might encode feedback resistors in their regulatory circuits. Then, by using a combination of mathematical theory and single-cell real-time imaging experiments, we show that a feedback resistor in the HIV Tat transcriptional circuit likely allows the HIV virus to enter into latency. We postulate that feedback resistors may give increased stability and control in the complex noisy signaling environment of the cell.

  3. Hopf bifurcations in time-delay systems with band-limited feedback

    E-Print Network [OSTI]

    Lucas Illing; Daniel J. Gauthier

    2005-07-20T23:59:59.000Z

    We investigate the steady-state solution and its bifurcations in time-delay systems with band-limited feedback. This is a first step in a rigorous study concerning the effects of AC-coupled components in nonlinear devices with time-delayed feedback. We show that the steady state is globally stable for small feedback gain and that local stability is lost, generically, through a Hopf bifurcation for larger feedback gain. We provide simple criteria that determine whether the Hopf bifurcation is supercritical or subcritical based on the knowledge of the first three terms in the Taylor-expansion of the nonlinearity. Furthermore, the presence of double-Hopf bifurcations of the steady state is shown, which indicates possible quasiperiodic and chaotic dynamics in these systems. As a result of this investigation, we find that AC-coupling introduces fundamental differences to systems of Ikeda-type [Ikeda et al., Physica D 29 (1987) 223-235] already at the level of steady-state bifurcations, e.g. bifurcations exist in which limit cycles are created with periods other than the fundamental ``period-2'' mode found in Ikeda-type systems.

  4. On the Fundamental Feedback-vs-Performance Tradeoff over the MISO-BC with Imperfect and

    E-Print Network [OSTI]

    Gesbert, David

    On the Fundamental Feedback-vs-Performance Tradeoff over the MISO-BC with Imperfect and Delayed--This work considers the multiuser multiple-input single-output (MISO) broadcast channel (BC), where. Specifically, this work provides a novel DoF region outer bound for the general K- user M ×1 MISO BC

  5. Spatial and Temporal Power Allocation for MISO Systems with Delayed Feedback

    E-Print Network [OSTI]

    Bhashyam, Srikrishna

    Spatial and Temporal Power Allocation for MISO Systems with Delayed Feedback Venkata Sreekanta@ee.iitm.ac.in Abstract-- We determine the minimum outage probabil- ity of multiple-input single-output (MISO) channels control. I. INTRODUCTION The minimum outage probability of multiple-input single-output (MISO) channels

  6. Optimization of Feedback in a MISO Downlink with Energy Harvesting Users

    E-Print Network [OSTI]

    Uysal-Biyikoglu, Elif

    Optimization of Feedback in a MISO Downlink with Energy Harvesting Users Mahdi Shakiba channel states) in order to maximize certain throughput goals. While the MISO chan- nel capacity from to the energy budget of the users. Note that in the Multi Input Single Output (MISO) channel (with m antennas

  7. Linear Control of Nonlinear Systems The Interplay between Nonlinearity and Feedback

    E-Print Network [OSTI]

    Nikolaou, Michael

    1 Linear Control of Nonlinear Systems ­ The Interplay between Nonlinearity and Feedback S. Alper computational methodology that addresses the question of when and what linear control is adequate linear and/or b. the controlled process will be operating closely enough to a steady state for its

  8. Linear Feedback Control Input under Actuator Saturation: a Takagi-Sugeno Approach

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Linear Feedback Control Input under Actuator Saturation: a Takagi-Sugeno Approach Souad Bezzaoucha into account the effect of saturation throughout the design procedure, a controller that may be linear. The third strategy is a two-step approach in which a nominal linear controller is first constructed

  9. An LQ sub-optimal stabilizing feedback law for switched linear systems

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    An LQ sub-optimal stabilizing feedback law for switched linear systems P. Riedinger J.-C. Vivalda linear switched system based on the optimization of a quadratic criterion. The main result provides is a challenging task. LQ regulators are widely used for the control of linear systems because of their simple

  10. Retrieval and Feedback Models for Blog Distillation Jonathan Elsas, Jaime Arguello, Jamie Callan, Jaime Carbonell

    E-Print Network [OSTI]

    Carbonell, Jaime

    Retrieval and Feedback Models for Blog Distillation Jonathan Elsas, Jaime Arguello, Jamie Callan and results for the Feed Distillation task in the Blog track at TREC 2007. Our experiments focus on two Wikipedia. 1 Introduction Blog distillation (or "feed search") is the task of finding blog feeds

  11. Sensorless Adaptive Output Feedback Control of Wind Energy Systems with PMS Generators

    E-Print Network [OSTI]

    Boyer, Edmond

    1 Sensorless Adaptive Output Feedback Control of Wind Energy Systems with PMS Generators A. El the problem of controlling wind energy conversion (WEC) systems involving permanent magnet synchronous is to maximize wind energy extraction which cannot be achieved without letting the wind turbine rotor operate

  12. Publish date: 06/27/2011 ECE 3353: Feedback Control Systems

    E-Print Network [OSTI]

    Gelfond, Michael

    coordinator: Vittal Rao Textbook(s) and/or other required material: Modern Control Systems by Richard C. DorfPublish date: 06/27/2011 ECE 3353: Feedback Control Systems Credit / Contact hours: 3 / 3 Course to the analysis and design of automatic control systems. Control system concepts and controller design. Pre

  13. Haptic Rendering of Parametric Surfaces Using a Feedback Stabilized Extremal Distance Tracking Algorithm

    E-Print Network [OSTI]

    Gillespie, Brent

    Haptic Rendering of Parametric Surfaces Using a Feedback Stabilized Extremal Distance Tracking rendering. 1. Introduction Haptic rendering is the process by which virtual objects are made apparent to be felt and at the same time made available to be manipulated by a human user. Haptic render- ing requires

  14. Haptic Rendering of Parametric Surfaces Using a Feedback Stabilized Extremal Distance Tracking Algorithm

    E-Print Network [OSTI]

    Gillespie, Brent

    1 Haptic Rendering of Parametric Surfaces Using a Feedback Stabilized Extremal Distance Tracking representation of haptic rendering. Haptic rendering is the process by which virtual objects are made apparent to be felt and at the same time made available to be manipulated by a human user. Haptic rendering requires

  15. Leverage vs. Feedback: Which Effect Drives the Oil Market? Sofiane Aboura

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Leverage vs. Feedback: Which Effect Drives the Oil Market? Sofiane Aboura and Julien Chevallier represents the biggest swing in the history of oil. This fact shows that the oil market exhibits a tail risk.chevallier@dauphine.fr 1 halshs-00720156,version1-23Jul2012 #12;However, contrary to equity markets, oil volatility seems

  16. Feedback Control for Steering Needles Through 3D Deformable Tissue Using Helical Paths

    E-Print Network [OSTI]

    O'Brien, James F.

    Feedback Control for Steering Needles Through 3D Deformable Tissue Using Helical Paths Kris Hauser controller that steers a needle along 3D helical paths, and varies the helix radius to correct a model predictive control framework that chooses a needle twist rate such that the predicted helical

  17. Feedback stabilization of the resistive shell mode in a tokamak fusion reactor

    E-Print Network [OSTI]

    Fitzpatrick, Richard

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